Mouser Electronics, an Electronic component distributor that focuses on introducing new products to promote industry innovation, and KEMET jointly released a new e-book, focusing on new technologies and strategies for distribution network design. This e-book is called 7 Experts on New Approaches for Power Distribution Network Design (7 Experts join forces to offer advice: new methods of distribution network design), and outstanding engineers from companies such as KEMET, Analog Devices, and Samtec discuss in the book how to deal with precision The complex issue of powering digital circuits provides insight.
As the demand for high-density computing devices continues to grow, power distribution networks (PDNs) must provide efficient and reliable power to increasingly complex circuits. As a result, engineers are employing new strategies, techniques and techniques to overcome challenges in PDN design. A new eBook from KEMET and Mouser presents insights from several of the industry’s top engineering experts, offering a variety of sources of inspiration for designers facing similar challenges.
This eBook gathers perspectives from various experts on how to effectively address the PDN design requirements of high-density equipment. The book also provides quick links and ordering information for new KEMET products suitable for PDN designs. For example, the KEMET T540 and T541 are solid electrolytic capacitors with conductive polymer cathodes and offer extremely low equivalent series resistance (ESR) and higher capacitance retention at high frequencies.
“Do you know why the voltage difference between the two phase wires is 380V? First, let’s briefly talk about the line voltage and phase voltage: the line voltage is the voltage between the live wire and the live wire, which is 380V, and the phase voltage is any one of the three live wires. and the voltage between neutral, is 220V;
“
Do you know why the voltage difference between the two phase wires is 380V? First, let’s briefly talk about the line voltage and phase voltage: the line voltage is the voltage between the live wire and the live wire, which is 380V, and the phase voltage is any one of the three live wires. and the voltage between neutral, is 220V;
The voltages are all used by us after being stepped down by the transformer. The secondary side of the transformer is all star-connected. There are three live wires that are ABC three-phase. Do work at the neutral point and connect to zero, and lead out a zero wire. ;
We can clearly see from the voltage vector diagram that the line voltage is √3 times the phase voltage, and the voltage between any two items of A-phase B-phase C-phase drawn from the secondary side of the transformer is 380V, so the voltage between the two live wires is 380V. The voltage between them is 380V;
In addition, the phase voltage is the ground voltage of any one of the three-phase ABC, that is, the voltage to the working zero line. This is the phase voltage. The relationship between it and the line voltage can be seen from the vector diagram. It is a √3 times relationship. That is, the line voltage is √3 times the phase voltage; so the phase voltage is equal to 380% √3=219.4, which is what we often call 220V;
Finally, let me tell you that 220V and 380V are our common names. In fact, the actual voltage fluctuates up and down the two voltage values above. In actual operation, it does not run under the exact values of 220V and 380V.
With the construction and development of communication networks, in order to solve the coverage of network blind spots, a large number of outdoor base stations and outdoor communication equipment have emerged. Since these telecommunication devices are in a harsh external environment, the problem of uninterrupted power supply required by the communication devices has always been a major problem in the industry.
The communication power supply itself can basically meet the harsh outdoor environment, and the real bottleneck is the battery used outdoors. At present, outdoor batteries are difficult to install, easy to be stolen, and the service life of batteries is greatly affected by temperature. How to solve the impact of the outdoor environment on the battery and prolong its service life is very important. On the basis of comparing several methods used for outdoor batteries, this technology proposes a buried method for ventilated batteries, designs and applies a ventilated buried battery cabinet, and combines outdoor switching power supplies to increase monitoring systems to solve the problem of outdoor high temperature. Impact on battery life and moisture gas exchange in battery cabinets that may be encountered with buried batteries.
2 Purpose and meaning
The ventilated underground battery cabinet better solves the problem of DC uninterrupted power supply of outdoor base stations; improves the service life of outdoor power batteries; reduces the comprehensive use cost of outdoor base stations and saves comprehensive energy consumption; Long-term outdoor use opens up a viable avenue.
3 Current situation at home and abroad
There are reports on the use of buried batteries at home and abroad, but there is a problem that the humid gas in the battery cabinet buried in the ground corrodes the battery, thereby reducing the battery life. There is currently no good solution to this problem. The method introduced in this paper, through the monitoring system of the communication power supply, intelligently controls the ventilation fan of the buried battery according to the humidity in the battery cabinet, and through the actual use verification, it can better solve this problem and greatly improve the service life of the battery. This technology is still blank in China at present, and it has great promotion significance.
4 General idea
(1) The battery is buried in the ground to solve the problem of power supply for outdoor communication equipment, achieve better anti-theft and dust-proof effects, reduce the impact of outdoor high temperature on battery life, and prolong battery life.
(2) 12V or 2V batteries can be flexibly used for the burial of battery cabinets. The service life of 2V batteries is higher than that of 12V batteries, so 2V batteries are basically used for buried methods.
(3) Collect the humidity data in the box by installing ventilation fans and humidity sensors in the air duct of the battery cabinet buried in the ground.
(4) Monitor the humidity index in the battery cabinet through the monitoring unit of the communication power supply to determine the frequency of ventilation.
5 Technical solutions
(1) Selection of battery box material and structural processing
Considering that the battery box will be buried in the wet underground for a long time, it is proposed to use plastic to make the box body. At the same time, due to the large box body and many specifications, the method of mold injection is not used, and the plate welding method is used. The thickness of the plate is considered to be 12 mm – 15 mm.
(2) The placement and support of the battery box
Considering that the plastic battery box itself is not strong enough to support the battery, a flat platform is provided at the bottom of the plastic battery box to bear the weight of the battery. If the site is not convenient for masonry work, prefabricated cement boards can also be used.
(3) Waterproofing of battery box
The battery box is waterproof by welding. A waterproof rubber strip is added between the battery box and the box cover, and the waterproof rubber strip is compressed by appropriate fastening measures to achieve the purpose of waterproofing. In addition, the connection between the battery box, the box cover and the PVC pipe is also welded.
(4) Ventilation and heat dissipation of the battery box
Since a small amount of gas overflows during the trial process of the battery, there will be acid gas and moisture in the battery box, which needs to be discharged. First of all, through the proper arrangement of the intake pipe and exhaust pipe, natural breathing can be achieved. In addition, a fan is installed at the end of the exhaust pipe, which is connected through a dry contact and controlled by an independent monitoring unit of the switching power supply. Forced circulation is carried out regularly for about 10 minutes every day, which can completely discharge the acid gas and moisture in the battery box.
Through the independent monitoring unit of the outdoor switching power supply equipment, the control of the fan can be easily realized.
In order to prevent debris from entering the battery box through the intake pipe and exhaust pipe, install insect-proof nets on the nozzles of the intake pipe and exhaust pipe.
(5) Anti-theft problem of battery box
By installing an access control between the battery box and the cover, an alarm can be issued when the battery box and cover are separated.
6 Economic Benefit Analysis
China Mobile Longyan Branch builds about 200 outdoor base stations every year.
Compared with underground installation, there are still many shortcomings in ordinary installation, such as: ① ordinary installation has the problem of anti-theft problem that is difficult to solve; ② ordinary installation has the problem of H-bar load bearing; ③ ordinary installation can only use a maximum of 200AH batteries, and buried The installation does not have this limitation.
7 Conclusion
It can be seen from the above analysis that the ventilated underground battery cabinet saves 10,325 yuan per site per year. If Longyan builds 200 new sites per year, it will save 200 sites and 10,325 yuan/site = 2,065,000 yuan per year.
With the development of mobile services, the number of outdoor stations will increase, that is, more and more batteries are used outdoors. According to the current construction speed of Fujian Mobile, 2,000 new marginal stations will be built every year. If all of them adopt the ventilated battery buried technology, the annual investment saved by Fujian Mobile alone will reach 20.65 million yuan.
In the current international context of increasingly tight energy supply, the state vigorously advocates energy conservation and emission reduction. By adopting the ventilation-type buried battery cabinet, the service life of the battery will be increased by more than 3 times compared with the original one, and the annual cost savings of each site will reach more than 10,000 yuan. If it is promoted nationwide, it will save a lot of resources for the country and has great promotion value.
Netease Technology News March 3 news, according to foreign media reports, for those so-called “gig economy” practitioners who provide ride-hailing and delivery services, they are independent contractors and do not have many protection measures, so they are facing the new coronavirus. Threat of the spread of the virus.
The global spread of the virus has prompted many companies to instruct employees to stop traveling or telecommute, and the most vulnerable groups include gig workers like Uber or Lyft drivers. These people are at risk of infection while providing services and losing all their income if they stop working.
“The gig economy is filled with low-income independent contractors who don’t have great health insurance,” said Alex Rosenblat, research leader at the nonprofit Data & Society. will not be better protected than anyone else and therefore may be at higher risk.”
If these people are forced to continue to work because of a lack of income, the outbreak could spread faster. Rosenblatt believes the health risks posed by the outbreak could prompt a change in policy, as companies are held liable if drivers or passengers become infected.
Companies like Uber, Lyft, grocery delivery service Insta and food delivery service DoorDash all classify couriers or drivers as independent contractors, a classification that saves companies a lot of money because they don’t have to provide gig workers with health insurance and other benefits . Independent contractors also don’t have the right to unionize.
However, this situation is changing. The Silicon Valley Rise campaign, led by community group Working Partnership USA, is urging tech companies to include contractors and gig workers in their response plans. The campaign also requires companies to provide protective equipment, health insurance, sick leave, and ensure workers who take sick leave are not discriminated against when they return.
Spokespeople for Uber, Lyft and Insta all said they have dedicated teams within them to monitor the situation closely and ensure action is taken if necessary.
IXIA (Nasdaq-listed company, code name XXIA) is a world-class provider of high-performance IP network test solutions, 100% focused on developing IP test solutions. There are many customers and friends who want to systematically understand the latest progress of the IXIAIP test platform and the test solutions provided, so I will introduce it here.
2IXIA Unified Platform
The IXIA unified platform consists of three parts: chassis, test module and software. The organic combination of the three parts constitutes the most complete 2~7 layer IP test solution at present. Figure 1 is a schematic diagram of the overall testing scheme of IXIA.
Figure 1IXIA2~7 layer overall test scheme
2.1 Chassis
There are two types of IXIA chassis: rack-mounted and portable, which can be selected according to the needs of the test application and the number of ports.
The rack-mounted chassis OptixiaXM12 (see Figure 2) is the IP test platform with the highest performance and the widest range of test applications in the industry. It is suitable for multi-port and multi-user simultaneous use in the laboratory. It has attracted the attention of the market due to the following characteristics, especially the favor of existing users of IXIA.
Figure 2 OptixiaXM12 test frame
(1) Test modules, test software and even previous test configurations are fully compatible, and the performance is greatly improved, improving test efficiency and maximizing investment protection.
(2) It fully supports various applications of Aptixia, and completes 2~7 layers of testing on a single platform.
(3) High-speed backplane connection, modular software and hardware design, and clear real-time Display of LCD status, the operating status is clear at a glance.
(4) It supports the hot swap of the test module, which brings convenience to the test.
The portable chassis OptixiaXM2 has the same features as the XM12, but it is more flexible and suitable for use when you need to go out and test frequently. The OptixiaXM2 is shown in Figure 3.
Figure 3 OptixiaXM2 test frame
2.2 Test Module
IXIA100% focuses on the field of IP testing, and the products provided are all based on IP technology. Therefore, the corresponding test modules are mainly based on 10/100/1000M and 10G Ethernet interfaces. Of course, ATM, POS, PoE (PoweroverEthernet) and other interface types are also provided to meet various test needs. Among them, the gigabit module is the most widely used. There are many types of IXIA gigabit test modules to meet the test needs of different users. Here, we will focus on two modules, LSM1000XMV16 and ASM1000XMV12.
LSM1000XMV16 is the only high-density test module in the industry that can provide high-performance 2 to 7-layer testing (see Figure 4). The test module has the following features:
Figure 4 LSM1000XMV16 high performance test module
(1) High port density: One test board can simultaneously provide 16 10/100/100M electrical ports and 16 100/1000M optical ports (dual media interface type).
(2) High performance index: In the simulation of layer 2~3 routing protocols, two test ports can simulate the routing topology of carrier-class core routers at the same time. Other manufacturers may require more than 10 test ports to achieve similar performance.
800eBGPPeers and advertise 300k routes;
68OSPFAdjacencies and advertise 10k routes;
●22OSPFv3Adjacencies and advertise 1k routes;
4PEs and routed through 550kVPN;
● 50iBGP4+Peers and advertise 10k routes.
Therefore, this test module is the first choice for core routing equipment testing. The above test data is fully verified and approved by IsocoreLab, a third-party testing laboratory. The detailed evaluation report can be found in the link below:
In the simulation of the 4~7 layer application protocol, each port of HTTPConnectionRate can reach 15k, and each port of HTTPGoodput (effective throughput) can exceed 950Mbit/s, and the performance increases linearly with the increase of the number of ports. And each test port can emulate the client or server side.
ASM1000XMV12 (see Figure 5) is the only test module in the industry that can generate and analyze 10G application layer wire-speed traffic. The test module has three working modes.
Figure 5ASM1000XMV12
●Non-aggregation mode: 12 10/100/1000Mbit/s electrical ports and 12 100/1000M optical ports provide the test function of Layer 2~7.
●Gigabit aggregation mode: PCPUs with 12 ports can be aggregated arbitrarily through the switching matrix, improving the processing capability of each port at Layer 4 to Layer 7.
●10 Gigabit aggregation mode: 12 Gigabit PCPUs are aggregated to 10 Gigabit ports through the switch matrix to generate 10G application layer wire-speed traffic. This is also the most typical and commonly used application mode, which is used for performance testing of application-layer devices such as high-performance 10G firewalls, high-performance application gateways, and DPI. FIG. 6 is a schematic diagram of 10G aggregation.
2.3 Test software
(1) AptIXIAIxNetwork
AptixiaIxNetwork is the flagship tool for testing switches, routers, DSLAMs, BRAS and other layer 2~3 forwarding devices. It generates millions of data traffic by simulating millions of routes and reachable hosts, and realizes the control level and The stress test combined with the data plane can also perform real-time analysis on the performance of the control plane and the data plane. The main supported protocols include: BGP, BGP+, MBGP; OSPFv2/v3, OSPFv3; BFD; ISISv4/v6, ISISv6; RIP, RIPng; L2MPLSVPN, VPLS (LDP and BGPBased); L3MPLSVPN, MulticastVPN, MulticastVPNv6; LDP, RSVP-TE ; IGMPv1/v2/v3, MLDv1/v2, PIM-SMv4/v6; STP, RSTP, MSTP, PVST+, RPVST+; EIGRP; DHCPv4/v6; PPPoX, L2TP, 802.1x, 802.1xwithNAC(L2NAC), EAPoUDP(L3NAC) ;EthernetOAM, CFM, (IEEE802.3ah, IEEE802.1ag) ITU.Y1731.
The main features are:
●Easy-to-use protocol wizard, simulates the Internet-level routing topology, and quickly and accurately determines the routing capacity of network equipment.
●Powerful traffic wizard, can generate millions of data traffic according to the simulated network and host.
●The flexible test scheduling function can simulate the dynamic jitter and change of the topology structure in real time; measure the performance of network convergence.
●ApplicationTraffic (HTTP, POP3, SMTP, Voice, Video, etc.) QoE test of overRoutes.
● RFC2544 benchmark test method OverRouting benchmark performance test.
● “white box” test method (real-time acquisition of device information under test through SNMP). It should be noted that all Aptixia applications support this feature, and the running status of the device under test can be observed in real time during the test.
●The “flow detection” function can find out the “best” or “worst” performance flow in real time from the massive flow, which greatly improves the test efficiency.
●The “multi-field tracking” function can facilitate the performance testing of important features such as VLAN leakage and QoS re-marking.
(2) AptixiaIxLoad
AptixiaIxLoad is a professional tool for evaluating the performance of three-in-one voice, data, video networks and devices and information security equipment. IxLoad simulates users of IPTV and 3-in-1 network services and related protocols to ensure user quality of experience (QoE). Supported protocols include:
●Data class (Data) protocol
——TCP connection number performance test;
——HTTP(1.0/1.1) and Web server function test;
——SSLv2, SSLv3, TLSv1;
– FTP;
– E-mail protocol (POP3, IMAP, IMAP);
——RTSP/RTP;
—Telnet;
– DNS;
–LDAP;
–DHCPClient;
——TFTPClient;
– Stateful capture and playback AppReplay of private protocols;
——IGMPv1/v2/v3, BroADCastTV supported by MLDv1/v2 protocol, test channel switching time, I-FrameJoinLatency and video quality MDI, MOS_V and PEVQ;
——VoD under RTSP/RTP protocol;
– Microsoft IPTV (MSTV) test support.
●Network layer access mode: IP access includes support for VLANs (802.1Q, Q-in-Q, 802.1p), PPPoE access, IPSec access, and DHCP (including Option82) access.
(3) AptixiaIxAutomate
AptixiaIxAutomate is an automated test suite that enables quick setup of common test cases. The supported test suites include:
●Layer 2~3 data plane forwarding test: RFC2544 (updated to the latest test specification in 2007, adding IPv4/v6 test features), RFC2889, advanced switching feature test (VLAN, DataIntegrity, SequenceChecking, ErrorHandling, etc.), QoS test, IPv4/v6Tunneling, BroadbandPerformance, LACP, MEF14 test suite.
AptixiaTestConductor is a management tool that can realize automated testing without writing scripts. It is a comprehensive IXIA and third-party test application and device management platform. Key features include:
● Deployment does not require a lot of personnel training, and test engineers without any programming experience can complete complex tests.
●It is a software product that does not include any new hardware investment. Users can quickly deploy tests and regression tests as long as they already own various test equipment and test tools of IXIA. Of course, if there is no IXIA related equipment, you can also run any third-party test script or test program on TestConductor, and use TestConductor’s powerful regression testing function for complete testing.
●It is a new generation of test management platform. It has no conflict with the test platform developed by itself in essence. It mainly completes the configuration and management functions in a large number of regression tests.
●It has a powerful DUT configuration module, which can record and replay DUT configuration instructions from DUTs connected with various interface types. It is convenient for users to configure and realize one-click conversion from graphics to scripts. Users no longer need to write complex TCL configuration scripts to configure DUT.
●Run the scheduler, which uses an Outlook calendar to facilitate the user to define the scheduling sequence. The test can be executed in sequence or in parallel to make the best use of test resources.
●The real-time data obtained by various resources including DUT can complete some extended functions, such as using these data to calculate and determine whether the test is successful or not. After the test is completed, the test result will be notified by E-mail automatically.
●Integrated with MercuryQualityCenter, users can start, stop and detect regression tests in QC, and all test results will be uploaded and saved in QC.
3IXIAIP test plan
The above-mentioned unified test platform of IXIA can realize a complete 2~7 layer test scheme with the corresponding test tools. The tests that can be realized mainly include:
(1) Traffic analysis and testing of layer 2~3 forwarding equipment;
(6) PON system performance and service verification test;
(7) Testing of information security products (firewall, IDS/IPS, spam gateway and NAC certified equipment, etc.);
(8) IPSec gateway performance test;
(9) SSLVPN test;
(10) IPTV equipment and network testing;
(11) Voice/IMS performance test;
(12) Verification of new services and end-to-end network testing;
(14) Various application server performance tests;
(15) DPI (Deep Packet Inspection) device test;
(16) Home gateway/e-home terminal test;
(17) WLAN product testing;
(18) Wi-Fi handheld terminal performance test;
(19) Protocol Conformance Test (ConformanceTest) test;
(20) Automated testing.
3.1 Routing and MPLS Test Scenario
Routing and MPLS are the core technologies of IP, and they are also the most widely used test fields for the IXIA test platform. IXIA high-performance test platform and test modules, flagship test software IxNetwork provides the guarantee for the test. The corresponding test features have been mentioned in the previous IxNetwork software introduction, and will not be described in detail here. Figure 7 is a schematic diagram of the MuticastVPN test provided by IXIA.
Figure 7 MulticastVPN test schematic
3.2 Carrier Ethernet Test Solution
IXIA is also a leading carrier Ethernet test provider, an important member of MEF, IETF, ITU, and a key IP test provider for Nortel Networks CarrierEthernetEcosystem (see link: http://www .ixiacom.com/news_and_events/press_releases/Display.php?skey=157). Key features include:
(1) Support MEF9 and 14. It is a test tool recommended by IometrixLab and is completely written according to the corresponding test specifications;
(2) OC48/192RPR, LCAS, GFP and other features support;
(3) Q-in-Q, PBB/PBT support;
(4) VPLS/MPLS, T-MPLS support;
(5) EthernetOAM/CFM, ITUY.1731 support.
3.3 IPTV test plan
IXIA is currently in an absolute leading position in the field of IPTV testing, with more than 200 IPTV users worldwide (see link: http://www.ixiacom.com/news_and_events/press_releases/Display.php?skey=151), the main features include :
(1) Channel switching time test, I-FrameJoinLatency test;
(2) Based on each video stream quality test – MDI, MOS_V;
(3) Full-Reference analysis of video quality (PEVQ);
(4) The subjective and objective evaluation method of video quality;
(5) Real-time monitoring of network video stream quality (Passive Video Monitoring) and video quality analysis;
(9) Performance test of VoD and video server (BTV and VoD);
(10) Test of IGMP/MLD switch and IPDSLAM;
(11) Test of IP set-top box (STB) and CableModem;
(12) QoE performance test of TriplePlay network.
3.4 Application layer business performance and information security test scheme
User Quality of Experience (QoE) testing is one of the current testing hotspots. All these tests are based on actual business simulations. IXIA currently supports the most extensive application layer protocols (see the IxLoad product introduction for details). Figure 8 is a schematic diagram of the service performance test. The main features include:
Figure 8 Schematic diagram of application layer service performance test
(1) QoE test of protocols such as Data (HTTP, FTP, SMTP, P2P), Video (IGMP, MLD, RTSP), Voice (SIP, MGCP).
(2) Support IPv4 and IPv6 versions of various application layer protocols.
(3) Support performance test of AAA/RADIUS, DNS, DHCP, LDAP and other servers.
(4) Generate malicious traffic to implement performance testing of information security devices, including firewalls, IDS/IPS, spam gateways, content detection devices, IPSec gateways, and SSLVPN.
(5) IP, PPPoE, IPSec, DHCP and other flexible and diverse access methods.
(6) Various real business traffic model settings such as pulse, Poisson, burst, step, and linear increase.
3.5 Voice and IMS Test Scenarios
IXIA offers leading VoIP and IMS testing on the same platform with key features including:
(1) SIP, MGCP Voice Quality Assessment (MOS) for each voice call.
(2) Simulation and performance test of VideoPhone.
(3) Support for a variety of voice compression coding, including the latest AMR and iLBC support.
(4) IMS user plane test.
(5) Targeting IP performance testing (mass UE emulation and CSCF testing).
(6) Complete TLS and IPSec testing functions (IMS security testing).
3.6 IXIA product features and advantages
IXIA products are widely recognized by users, mainly due to the following features and advantages:
(1) The real 2~7 layer test platform: each port of the test module can generate 2~3 layers of traffic (including protocols and ordinary traffic), and can also generate state (Data, Voice, Video) 4 ~7-layer application layer traffic; this is the biggest feature of the IXIA platform.
(2) Port-based multi-user operation, each port has independent CPU and memory, high performance index and can greatly improve the use efficiency; this is the biggest technical advantage of IXIA products.
(3) Open structure and automated operation: each test port runs a standard Linux protocol stack, which can easily integrate new technologies according to customer needs, and provide “what you see is what you get” automated test scripts; this can make IXIA test The efficiency of using the platform is maximized.
(4) High port density parallel and stable test: IXIA products have been verified in the user laboratory, and support the test of 1500 GE ports at the same time; a maximum of 40 users in one chassis can perform different operations at the same time, which can run stably for a long time.
4 Conclusion
The 2~7 layer IP related tests that users care about, including functional testing, performance testing and conformance testing, can be easily implemented on the IXIA unified testing platform. The real 2~7 layer test platform provided by IXIA effectively protects the user’s investment and improves the use efficiency.
As the No. 1 supplier of IP test instruments to many leading equipment manufacturers, IXIA will continue to invest heavily in research and development of new technologies on the same test platform, develop together with our customers, and promote the development of IP test technology.
“In recent years, driven by downstream markets such as new energy vehicles, photovoltaics and energy storage, and various power supply applications, silicon carbide power devices have made great progress. Faster switching speed and better temperature characteristics greatly reduce system losses, improve efficiency, and reduce volume, thereby achieving high efficiency and high power density of the converter. However, wide-bandgap (WBG) devices like SiC also present design challenges for application R&D, leading to industry selection and trade-offs for SiC MOSFET planar and trench gates, as well as their inrush current, short-circuit capability, gate There are still doubts about reliability, etc.
“
In recent years, driven by downstream markets such as new energy vehicles, photovoltaics and energy storage, and various power supply applications, silicon carbide power devices have made great progress. Faster switching speed and better temperature characteristics greatly reduce system losses, improve efficiency, and reduce volume, thereby achieving high efficiency and high power density of the converter. However, wide-bandgap (WBG) devices like SiC also present design challenges for application R&D, leading to industry selection and trade-offs for SiC MOSFET planar and trench gates, as well as their inrush current, short-circuit capability, gate There are still doubts about reliability, etc.
How does SiC MOSFET perform?
650V-1200V voltage level SiC MOSFET commercial products have developed from Gen 2 to Gen 3. With the development of technology, the cell width continues to decrease, the specific on-resistance continues to decrease, and the device performance exceeds that of Si devices. Inrush current, short circuit Reliability issues such as capability and gate oxide reliability have attracted much attention. So how much surge current can the SiC MOSFET body diode withstand? What is its short-circuit capability? How to ensure gate reliability?
The magnitude of the surge current resistance of the body diode of a SiC MOSFET is proportional to the size of the chip. For example, Pinjie Semiconductor uses its own 10ms sine half-wave surge limit test platform and 10us square wave half-wave surge limit test platform to sample its 1200V SiC MOSFET P3M12080K3 for 10ms IFSM >120A, 10us IFSM>1100A.
Figure 1 10ms surge limit test platform
Figure 2 10us surge limit test platform
As for the short-circuit capability, compared with Si IGBT, SiC MOSFET has higher current density and thinner gate oxide layer, and its short-circuit capability is weaker than that of Si IGBT, but it still has a certain short-circuit capability.
The following table shows the short-circuit capability of some products of Pinjie semiconductor:
Table 1 Short-circuit withstand capability of 1200V/650V MOSFET devices
The reliability of the gate of Pinjie Semiconductor is strictly in accordance with the AEC-Q101 standard, and the HTGBR and HTRB experiments are carried out at a temperature of 175°C with negative voltage and positive voltage (-4V/+15V) on the gate respectively. No product failure for 1000h. In addition to the 1000h hour experiment required in conventional AEC-Q101, Pincher has done extensive research on gate lifetime. SiC MOSFETs generally have a higher probability of early failure due to the presence of orders of magnitude larger impurity defects at the SiC/SiO2 interface than Si/SiO2. In order to improve the gate reliability of SiC MOSFETs, it is important to identify and isolate early failures through screening. Pinjie Semiconductor established a gate oxide acceleration model through TDDB experiments and established a screening mechanism to eliminate potential failure devices (see previous pushes).
In addition to TDDB, when a normal device is used, the threshold voltage of SiC MOSFET will drift due to the generation of defects or charge and discharge at the semiconductor-oxide interface, and the drift of the threshold voltage may have a significant impact on the long-term operation of the device. Pincher Semiconductor applied a constant DC bias to the SiC MOSFET under high temperature conditions and observed the amount of change in its threshold voltage. Generally, when a forward bias stress is applied, the threshold voltage shifts to a higher voltage; when a negative bias stress is applied, the threshold voltage shifts to a lower voltage. This effect is caused by the carrier trapping at or near the SiC/SiO2 interface. The negative high voltage is the trapping of holes near the MOS interface, resulting in more hole traps; on the contrary, the positive high voltage causes the trapping of electrons. Of course, for some competing products, the threshold voltage shifts to a lower voltage when a forward bias stress is applied; when a negative bias stress is applied, the threshold voltage shifts to a higher voltage. This is caused by the accumulation of mobile ions at the SiC/SiO2 interface. Positive mobile ions accumulate at the SiO2/SiC interface due to positive bias, resulting in a negative shift in threshold voltage; Mobile ions accumulate at the poly/SiO2 interface, causing a positive bias in the threshold voltage. In order to evaluate the threshold voltage drift of the device during use, Pinjie Semiconductor has conducted a large number of BTI experiments, and established a PBTI&NBTI model based on the experimental data. With the help of the model, the threshold voltage drift of the device under different temperatures and gate voltages can be known. Taking the P3M12080K4 product as an example, this product is used in extreme applications (PBTI:Vgs=19V, TA=150℃) using 20-year threshold voltage drift (+0.348V), the product is under extreme application conditions (NBTI: Vgs=-8V, TA=150°C) using the 20-year threshold voltage drift (-0.17V).
Advantages and disadvantages of Cascode, plane gate, trench gate
In order to improve the energy efficiency of high-voltage power supply systems, semiconductor manufacturers are actively developing economical and high-performance silicon carbide power devices, such as Cascode structure, silicon carbide MOSFET planar gate structure, silicon carbide MOSFET trench gate structure, etc. What impact do these different technologies have on the application of silicon carbide power devices, and how to choose?
First, Cascode refers to the use of Si MOSFETs and normally-on SiC JFETs connected in series, as shown in Figure 3. When the Si MOSFET gate is high, the MOSFET turns on shorting the GS of the SiC JFET, thus turning it on. When the gate of the Si MOSFET is low, its drain voltage rises until the GS voltage of the SiC JFET reaches the negative voltage at which it is turned off, at which point the device turns off. The main advantage of the Cascode structure is that the same on-resistance has a smaller chip area. Since the gate switch is controlled by the Si MOSFET, the customer can use the Si driver design in the application, and does not need to design the driver circuit separately.
Figure 3 Schematic diagram of SiC Cascode structure
Pinjie Semiconductor believes that the Cascode structure is only a transition product from Si products to SiC products, because the Cascode structure cannot fully exert the unique advantages of SiC devices. First, the high temperature application of Cascode is limited due to the integrated Si MOSFET, especially its high temperature Rdson will reach 2 times that of normal temperature; secondly, the device switching is controlled by Si MOSFET, so the switching frequency is much lower than that of normal SiC MOSFET devices, which is Since the dv/dt of JFET and Si MOSFET can only reach below 10V/ns, the dv/dt of SiC MOSFET can usually reach 30V/ns~80V/ns. These shortcomings make it impossible for Cascode to reduce the size of passive components, so as to reduce the overall system volume and cost; finally, although the Cascode structure uses SiC high-voltage JFET devices to withstand the bus voltage, during the switching process, The output capacitance of the MOSFET and JFET will still divide the voltage. When there is voltage oscillation in the loop, the low-voltage Si MOSFET still has the risk of being broken down.
The main advantage of SiC MOSFET trench gates comes from the vertical channel, which not only improves the carrier mobility (due to the higher mobility of the SiC (1120) plane than the (0001) plane) but also reduces the cell size This results in a lower specific on-resistance than a planar MOSFET. However, because SiC is very hard, the process difficulty and control requirements to obtain a uniform, smooth and vertical etched surface are very high, which is why only Infineon and Rohm have introduced trench gate SiC MOSFETs. The trench gate process not only has very high requirements for process realization, but also has certain risks in terms of reliability. First, the gate oxide quality of the trench gate is at risk due to the limitation of surface roughness and angle after trench etching; secondly, due to the anisotropy of SiC, the thickness of the oxide layer on the sidewall of the trench and the oxide layer at the bottom of the trench are at risk. The thickness is different, so special structures and processes must be used to avoid breakdown at the bottom of the trench, especially at the corners, which also increases the uncertainty of the reliability of the trench gate oxide; finally, due to the structure of the trench MOSFET, the trench The electric field strength of the gate oxide is higher than that of the planar type, which is why Infineon and Rohm do single-sided and double trenches.
SiC MOSFET planar gate is the earliest and most widely used structure, and the current mainstream products use this structure. Pinjie semiconductor products are also used in planar gate MOSFET structure. Based on the planar gate structure, Pinejie has released SiC MOSFETs for various voltage platforms from 650V to 1700V, and has been successfully mass-supplied in leading new energy companies to achieve “on-board”.
“In the age of intelligence, ‘5G + Beidou’ will become the most important infrastructure.” On June 23, Liu Jingnan, an academician of the Chinese Academy of Engineering and a professor at Wuhan University, watched the live webcast of the launch of the 55th Beidou navigation satellite. Beidou-3 global network, Beidou navigation gradually from China to the world stage. He believes that there will be plenty of opportunities to realize the integration and mutual empowerment of “5G+Beidou”, which will generate disruptive technologies and create trans-century brilliance.
In the mid-1990s, Liu Jingnan led the team to participate in the Beidou seminar. In more than 20 years, from Beidou-1 to Beidou-3, he has conquered many key technologies of Beidou satellite system. Solved the problem that the Beidou-2 satellite could not serve during the attitude transition period (about 15 days per half year), established the first Beidou high-precision international analysis center in the Asia-Pacific region, and realized the independent control of the key technology of high-precision data processing of my country’s Beidou heterogeneous constellation .
Liu Jingnan said: “Now the time accuracy of communication and power systems are all microseconds, and the Beidou timing accuracy is 20 to 30 nanoseconds. Through ground-based enhancement and space-based enhancement, the time accuracy can be 1 nanosecond or better than 1 nanosecond. In nanoseconds, the real-time position can be accurate to 1 centimeter, and the post-event accuracy in a specific field can be 1 millimeter.”
5G is the infrastructure of the intelligent era. It has high bandwidth, high speed, large capacity, low power consumption, low latency, interconnection of all things, and information can be sensed and adjusted. 5G provides basic support for meeting the application needs of users and industries such as virtual reality, intelligent manufacturing, and autonomous driving in the future. Liu Jingnan said that the delay of 5G is millisecond-level, but it cannot realize the remote control of the car; and its network location is virtual, these problems must be solved.
Solving problems requires a new infrastructure, which is Beidou. Positioning, navigation, perception of time and seasons themselves are biological intelligence generated by natural evolution. The “5G + Beidou” in the intelligent era can impart this biological intelligence to machines and the environment, and give full play to the intelligence advantages of machines and network environments.
The ubiquitous mapping capability based on “5G+Beidou” is an extension of human positioning, navigation, and time perception intelligence based on modern technology. An enabling technology that supports wide-area and global intelligent collaborative control.
“Beidou high-precision navigation + 5G + high-precision map” will open up new applications in vehicle lane-level monitoring, vehicle automatic driving and intelligent unmanned driving. In the future, driverless vehicles and intelligent networked vehicles are essentially a high-precision intelligent mobile computing platform, which needs to perceive and recognize the outside world, and must have accurate location and time services. Therefore, every intelligent connected car and every unmanned car is not only a means of transportation in the Internet era, but also an intelligent mobile computing platform. Sharing the data of these platforms with everyone will generate endless new applications and new formats. .
Beidou location services will also achieve cross-border integration: including cross-system integration, which is compatible, interoperable and interchangeable with other global satellite navigation systems; cross-regional integration. Cross-industry integration, indoor and outdoor multi-sensor fusion, to provide a ubiquitous intelligent spatiotemporal location service “Beidou+”.
Liu Jingnan said that Beidou is an enabling technology. Through the integration with other technologies, Beidou gives these technologies new functions in time and space, so that these technologies can be improved in dimension and efficiency. With the development of the times, there is great room for imagination in future applications.
Recently, Iora health, a primary care clinic operating company, announced that it has received US$126 million in Series F financing, led by Premji Invest (founded by the chairman of Wipro). This round of financing is mainly used to develop existing businesses, apply for EHR (Electronic Health Records System for Medical Insurance) certification, and add new features to its technology platform Chirp.
Iora Health said it plans to use the new funding to accelerate the company’s growth and add new features to its technology platform Chirp. It has also previously received funding from Flare Capital Partners, Temasek, F-Prime Capital, Cox Enterprises, Devonshire investors, 406 Ventures, Polaris Partners and Khosla Ventures, among others.
Iora Health is a service provider that provides primary healthcare for the elderly. Founded in 2011 and headquartered in Boston, it currently operates 48 clinics (up from 24 in 2018), focusing on providing collaborative care models for people over the age of 65. Support for Medicare patients.
IoraHealth said that under this model, doctors will charge a fixed fee for each patient’s visit instead of charging for each service provided; in addition, patients have not been equipped with health coaches, and a self-developed software platform is provided for both parties to record and share. information. Overall, Iora Health has three innovations:
1) Adopt a non-traditional fee-for-service model, that is, do not accept self-paying patients, all from cooperative insurance and self-insured employers, to ensure unimpeded access to patients’ authorized needs and complete billing, and provide personalized care accordingly Program;
2) Effectively use new technologies such as big data, that is, use the electronic medical record system to grasp all the data of the patient, and reasonably classify and track the patient;
3) Nursing teams in diverse institutions, i.e. many health coaches in addition to hiring doctors, nurses and behavioral health specialists.
We know that elderly care and health care for the elderly are a major challenge on a global scale. In the United States alone, the elderly population in the United States exceeds 52.2 million, of which about 80% have at least one chronic disease. The traditional medical service model established for the treatment of acute diseases cannot meet the long-term needs of the elderly for primary health care; in addition, the high cost will also impose a huge burden on the health care system.
In China, similar problems are particularly prominent. Iora Health is constantly breaking the above-mentioned predicament through an innovative model, that is, starting with basic medical care services, operating according to the effect, paying attention to the health management of customers and reducing the probability of illness. With the successful fundraising of Iora Health, competition in the industry is heating up. Other companies are also keeping a close eye on health insurance, such as CVS, which recently hired Iora’s former chief marketing officer to lead clinic operations.
At present, many companies around the world have been involved in primary health care services for the elderly, such as , , . In terms of model, there are also benchmarking companies in China, such as Ping An Good Doctor, Penguin Almond, etc., but they are mainly aimed at the health management of the general public; in the field of elderly care, only a few players such as Taikang Pension have slightly different models.
However, with the deepening of the aging population, the advancement of primary medical care, and the development of long-term care insurance, China is also expected to have a primary medical care service platform similar to Iora Health.
C114 (Reuters) – The Trump administration has notified Huawei suppliers, including chipmaker Intel, that it will withdraw their permission to sell to the Chinese company, people familiar with the matter said. of certain licenses and intends to reject dozens of other applications to supply Huawei.
Reuters said it could be the last action against Huawei under U.S. Republican President Donald Trump and the latest in a long-running effort to undercut the world’s largest telecommunications equipment maker.
The notices came amid a flurry of U.S. actions against China in the final days before the Trump administration’s curtain call. Democrat Joe Biden will be sworn in as U.S. president on Wednesday.
An Intel spokesman had no immediate comment, and a Commerce Department spokesman did not immediately respond to a request for comment.
In an email documenting the actions seen by Reuters, the U.S. semiconductor Industry Association said on Friday that the Commerce Department “intentionally rejects numerous license applications for exports to Huawei and withdraws at least one previous license application. License issued”. A person familiar with the matter, who asked not to be named, said more than one license was to be revoked. Eight licenses from the four companies will be revoked, one of the sources said.
Japanese flash memory chip maker Kioxia has had at least one license revoked, two sources said. The company’s predecessor was Toshiba Storage Corporation.
The American Semiconductor Industry Association said in an email that the actions involved a “wide range” of products in the semiconductor industry and asked if the companies involved had been notified.
The email noted that companies had been waiting “months” for a licensing decision, and that with less than a week left in the Trump administration, how to deal with a “denial” was a challenge.
Companies that receive notices of “Intent to Deny” will have 20 days to respond, while the Commerce Department has 45 days to notify those companies of any changes in the decision, or the decision will become final. The companies will then have 45 days to appeal.
In May 2019, the U.S. placed Huawei on the U.S. Department of Commerce’s “entity list,” restricting suppliers from selling U.S. products and technology to the company.
But while the U.S. has tightened restrictions on Huawei, some sales to Huawei have been allowed and others have been denied, including a requirement that sales of semiconductors manufactured abroad using U.S. technology must be approved by the U.S. government. license.
The latest U.S. move comes after about 150 licenses to sell goods and technology worth $120 billion had not been approved, a person familiar with the matter said, as U.S. agencies failed to agree on whether the licenses should be authorized. Permissions have been on hold.
Another $280 billion in licenses to sell goods and technology to Huawei have yet to be processed, but now face a higher chance of being rejected, the sources said.
A rule last August said 5G-capable products could be rejected, but sales of less advanced technology would be decided on a case-by-case basis.
The U.S. government’s latest decision follows six meetings between senior officials from the Commerce, State, Defense and Energy departments, starting on January 4, the sources said. Officials developed detailed guidance on which technologies would support 5G and then adopted the standard, the person said.
In doing so, officials rejected the vast majority of about 150 contested applications and revoked eight licenses, the sources said.
The U.S. action came under pressure from Corey Stewart, Trump’s recently appointed Commerce Department official. Corey Stewart spent two months at the U.S. Commerce Department before the end of the Trump administration, where he wants to pursue a tough China policy.
[Introduction]After years of research and development, Risen semiconductor Technology Co., Ltd. has launched silicon carbide MOS and SBD series products, which have been recognized by the market and customers, and are widely used in high-end server power supplies, solar inverters, UPS power supplies, motor drives, energy storage, charging piles and other fields.
Silicon carbide MOS chips have excellent high-frequency characteristics. In high-frequency applications, the traditional TO-247 package will restrict its high-frequency characteristics. In response to customer needs and to further improve the performance of SiC MOS, Risen Semiconductor has developed a four-pin TO-247 package (TO-247-4L) SiC MOS product.
1. Difference between TO-247 four-pin package and three-pin package
Compared with the three-pin package TO-247, the four-pin package TO-247 has one more pin, and the added pin is the driver source pin. The pin arrangement is changed from GDS in TO-247 three-pin package to DS(P)-S(D)-G, in which the second pin S(P) is connected to the load terminal, and the three-pin S(D) is connected to the driver terminal .
For the traditional three-pin TO-247 package. The back electromotive force VLS (=LS*dID/dt) is generated by the inductance component L of the source power supply line and the drain current slope dI dID/dt, and the voltage VGS is applied to the gate and source drain of the chip. This back EMF will reduce the actual applied voltage from the set gate voltage, and the switching speed, especially the turn-on speed, will be slowed down.
By adding a signal source terminal for gate drive, the current in the power supply line and the current in the gate drive line can be separated to reduce the effect of gate-source voltage inductance. The TO-247-4L in the four-pin package directly connects the source end of the drive side to the position of the chip, and is separated from the source line of the load side, so that it is not easily affected by the drive voltage. Thus, the high-speed switching performance of the silicon carbide MOS is improved.
2. Four-pin package (TO-247-4L) advantage
The TO-247-4L silicon carbide MOS in a four-pin package can give full play to the high-speed switching performance of the silicon carbide MOS itself. Compared with the traditional three-pin package TO-247, the switching loss can be reduced by about 30-35%, which can further reduce the loss of the circuit.
Turn-on loss: ID rise at turn-on for TO-247-4L packaged product with driver source pin (red dashed line) compared to TO-247 packaged product without driver source pin (light blue dashed line) faster. By comparison, it can be seen that the switching loss of the TO-247 package product (light blue line) is 2700J, while the TO-247-4L package product (red line) is 1700J, and the switching loss is reduced by about 35%, a significant reduction.
Turn-off loss: It can be seen from the waveform at turn-off that the switching loss of the TO-247 package product (light blue solid line) is 2100J, and the TO-247-4L package product (red solid line) is 1450J, and the switching loss is reduced by about 30%.
3. Risen Semiconductor Silicon Carbide MOS Series Products
After years of research and development, Risen Semiconductor now has a complete series of silicon carbide MOS products. Each type of product has both TO-247-3L and TO-247-4L packages, providing customers with more choices.
Risen Semiconductor has been committed to industry-leading product development. In the future, we will continue to promote the development of innovative components, and provide solutions including silicon carbide products to further reduce the power consumption of various devices.
