APR 2020 Power-efficient energy storage systemsRT BOX 1: THE ORIGINAL RT BOX 2: MULTI-CORE RT BOX 3: HIGH I/O COUNT Building blocks for HIL simulation and rapid control prototyping THE REAL-TIME FAMILY HAS GROWN Find specs and pricing at www.plexim.comEnergy storage is the gathering of energy produced to be stored from solar arrays or the electric grid and provide that energy to a house or business. New technologies are geared towards finding solutions that are entirely focused on energy efficiency and improving system yields. Battery storage systems are a key technology for future forms of mobility and energy conserva- tion. Developments in battery technology have led to the production of lithium-ion (Li-ion) bat- tery packs. Lithium-ion batteries required several years of theoretical and experimental study before they were marketed. In recent years, the efficiency of a battery in terms of how much energy it can deliver compared to its size and weight has improved considerably. The main challenges required to offer high performance are increased autonomy, high charging speed and reduced maintenance costs through new circuit and test solutions. In order for electric mobility to be successful, publicly accessible charging stations must be able to support smart applications such as Vehicle2Grid (V2G). Smart charging technology of- fers unnecessary radical changes to the current infrastructure for the distribution of electricity. One of the challenges that engineers are facing is undoubtedly that of the power devices to be used. In this issue, we will take a closer look at energy storage systems, and smart charging solutions to accelerate e-mobility. We will also take a first look at GaN transistors and test & meas- urements solutions. The performance of GaN shows that efficiency and performance have improved significantly, leading to several new applications that were not possible with silicon technology. Yours Sincerely, Maurizio Di Paolo Emilio Editor-in-Chief, Power Electronics News Energy Storage Systems By M. Di Paolo Emilio APRIL 2020 | www.powerelectronicsnews.com3 VIEW POINTTaiwan-based MINMAX Technology is one of the largest suppliers of DC-DC convert- ers and AC-DC power supply modules for general industrial equipment in Taiwan. Currently, the company is seeking stable demand for railway products from China; meanwhile, in Japan and Europe it has also experienced impressive growth in orders from the regions' railroad markets. With experience in research and design for over 30 years in power module segment, MINMAX has grown to become a competitive mod- ule supplier of applications across industri- al, medical, railway and power generation. For a railway system, power modules are one of the core components. Because of such importance, MINMAX usually co-de- signs the power modules with its railway system designer clients to ensure the sys- tem's quality. MINMAX railway certified converters are available for DC battery bus voltages of 24VDC, 36VDC, 48VDC, 72VDC, 96VDC, and 110VDC. Converters are also provided for output voltages of 5VDC, 12VDC, 15VDC, 24VDC, ±12VDC, and ±15VDC. Testing for voltage isolation, vibration, and shock and bump is approved to EN61373 requirements. Cooling, dry, and damp heat levels are approved to IEC- EN 60068-2-1, 60068-2-2, and 60068- 2-30 test requirements, as well as the EMC railway standards in EN50121-3-2. Advanced circuit topology provides effi- ciency of up to 93%, which allows for a baseplate temperature of around 105°C and a minimum of 3,000VAC input to out- put isolation with reinforced insulation. Converters are protected against overload, overvoltage and short-circuiting. They are approved to the EN45545-2 standards for fire protection to ensure system safety. Other features include remote power con- trol and voltage output trim and sense. For More Information ▶MIZI03 3W DC-DC Converter ▶MKZI10/20 10-20W DC-DC Converter ▶MTQZ50/75 50-75W DC-DC Converter ▶Worldwide DistributionContents VIEW POINT Energy Storage Systems 3 POWER SUPPLIES & ENERGY STORAGE Benefits of multilevel topologies in power-efficient energy storage systems 6 POWER SUPPLIES & ENERGY STORAGE Efficient & smart: PSB 10000 30kW battery test systems from EA 13 SEMICONDUCTORS GaN Transistor for Several Power Applications 18 TEST & MEASUREMENTS Optical Automotive Ethernet for Electrical and Hybrid Powertrains 26 NEWS Infineon adds D²PAK real 2-pin packages to its CoolSiC Schottky diode family 34 TDK: convection cooled DIN rail mount DC-DC converters deliver up to 250W per output 34 ST: synchronous-rectification controller for affordable, high- efficiency power adapters 34 PI’s SCALE-iDriver for SiC MOSFETs achieves AEC-Q100 automotive qualification 34 Transphorm’s GaN used in HZZH’s 98 percent efficient power module 35 Bel Power: fan-cooled PSU offers a maximum of 4000 W and adjustable output voltage 35 Silicon Labs: PoE portfolio powers the future of 5G small cells 35 Pre-Switch appoints Foxy Power to spearhead adoption of AI-based soft- switching power platform 35 POWER SUPPLIES & ENERGY STORAGE The Future of E-mobility is Smart 36 DESIGN Smart charging solutions accelerate e-mobility 41 VIDEO The power of Silicon Carbide – Interview to Anup Bhalla, VP of Engineering at UnitedSiC 44 SiC packaging technology – Interview to Ignacio Lizama, Engineer at ROHM Semiconductor 44 GaN technology for the future – Interview to Tony Astley, Director EMEA Sales @ GaN Systems 44 Real-Time Testing for power systems – Interview to Orhan Toker, VP Sales and Marketing @ Plexim 44 APRIL 2020 | www.powerelectronicsnews.com5Benefits of multilevel topologies in power-efficient energy storage systems By Peter B. Green, Principal Engineer, Infineon Technologies Americas WHAT ARE ENERGY STORAGE SYSTEMS? Energy storage is the gathering of energy produced to be stored and used later. Bat- tery energy storage systems are used to create utility independent solar-powered homes or businesses (termed residential or commercial ESS), which are referred to as “behind the meter”. In contrast utility-scale ESS are referred to as “before the meter”, used to supplement generated power dur- ing periods of high demand. Both cases utilize bidirectional power converters em- ploying different architectures, topologies, and power semiconductor technologies. APRIL 2020 | www.powerelectronicsnews.com6 POWER SUPPLIES & ENERGY STORAGEESS IN RESIDENTIAL SOLAR INSTALLATIONS Residential solar energy systems are tied to the utility power grid via inverters, which convert power from solar panels to AC elec- trical power during hours of sunlight. Ex- cess power can be sold back to the utility company but during hours of darkness, the end-user must still rely on the utility to sup- ply their electricity. Utility companies have been able to take advantage of these limita- tions by adjusting their pricing model moving residential customers to ‘time-of-use’ rates thereby charging more when no solar pow- er is available. Adding an ESS to the system enables users to combat this and protect themselves against high energy costs by so-called ‘peak-shaving’, storing electricity collected by their solar panels in batteries to supply their power requirements at any time. Developments in battery technology have led to the production of lithium-ion (Li- ion) battery packs with much higher charge storage per unit mass and unit volume than older technology lead-acid batteries. Com- bined with efficient bidirectional power conversion systems these can be used to create compact wall-mounted ESS units in the 3 to 12-kilowatt range able to supply a home for 24 hours or more. However, de- spite their energy density advantage Li-ion batteries have some disadvantages, par- ticularly with regards to safety, including a tendency to overheat or become damaged at high voltages. Safety mechanisms are required to limit voltage and internal pres- sures. Storage capacity also deteriorates due to aging leading to eventual failure after some years of operation. It is, therefore, necessary for each battery pack to include an electronic battery management system (BMS) to ensure safe and efficient operation. Unlike solar inverters an ESS must operate in two different modes re- quiring bidirectional conversion: 1. Charging mode, when the battery is being charged 2. Backup mode, when the battery is supplying power to connected loads. Residential ESS combined with solar pan- els is categorized into DC- or AC-coupled systems. In DC-coupled systems, a single hybrid inverter combines the outputs of a bidirectional battery converter and a DC- DC solar MPPT stage at a common DC bus, which then supplies a grid-tied inverter stage. However, AC-coupled systems (some- times called ‘AC batteries’) are becoming more popular since this type of ESS can be easily retrofitted to an already exist- ing solar installation not orig- inally equipped with energy storage because the AC-cou- pled ESS is directly tied to the grid. An additional advantage is the ability to be easily paralleled to provide greater pow- er capability and storage capacity. RESIDENTIAL ESS POWER CONVERTER ARCHITECTURE The figure 1 outlines an AC-coupled sys- tem based on a 48V Li-ion battery pack. Excess power can be sold back to the utility company but during hours of darkness, the end- user must still rely on the utility to supply their electricity. APRIL 2020 | www.powerelectronicsnews.com7 The entire system is typically housed in a wall-mounted enclosure. The battery pack includes an integrated electronic battery management system (BMS) needed to man- age the state of charge (SOC) of the individ- ual cells, which are typically rated at a nom- inal 3.2 V. Cell deterioration is minimized by preventing operation in over or undercharged states. The BMS contains specialized con- trol ICs combined with low-voltage MOSFET switches based on trench technology such as Infineon’s OptiMOS TM or StrongIRFET™ families, typically in the 80 to 100V range. In this example, the power conversion sys- tem is separated into three stages, each of which supports bidirectional power conversion based on active power switch- es rather than diodes. There are sever- al possible topologies, many of which are variations of the basic H-bridge. The following schematic shows a topolo- gy combining two parallel power conver- sion stages to share the power transfer: Stage 1: The first stage converts battery voltage (typically 48 V) to high-frequency AC to be stepped up through the trans- former. In this example, a resonant topol- ogy is chosen to operate with zero voltage switching during backup mode to maximize efficiency by avoiding switching losses as much as possible. In charging mode, this stage operates as a synchronous rectifier. Figure 2: A possible converter topology for residential ESS Figure 1: Basic block diagram for a residential energy storage system APRIL 2020 | www.powerelectronicsnews.com8 This stage switches at low voltage and high current for which 60 V trench MOSFET de- vices with very low R DS(ON) such as Infineon’s OptiMOS TM family are well suited. Such devices may be connect- ed in paral- lel. Packages with excellent heat dissipa- tion capabilities and very low para- sitic package inductance such as the DirectFET TM are ideally suited. Stage 2: The second stage operates at high voltage and relatively low current, perform- ing the function of synchronous rectification when the ESS is supplying power in back- up mode and converting high voltage DC to high-frequency AC during charging mode to be stepped down through the transformer. Since the bus voltage is typically between 400 and 500 V this stage would require 600- 650 V switches capable of switching at high frequency with the lowest possible switching and conduction losses. Wide bandgap silicon carbide (SiC) trench MOSFETs offer several advantages over silicon super-junction (SJ) devices, which make it possible to reach higher conversion efficiencies at power lev- els of several kilowatts and above. The higher critical breakdown field allows a given volt- age rating to be maintained while reducing the thickness of the device enabling lower on-state resistance. The Infineon CoolSiC™ MOSFET 650 V product family offers devices with R DS(on) as low as 27 mΩ. The higher ther- mal conductivity corresponds to higher cur- rent density and the wider bandgap leads to lower leakage current at high temperatures. The multiplication factor from 25°C to 100°C to the R DS(on) is 1.67 for CoolMOS™ and 1.13 for CoolSiC™. This means that in order to have the same conduction losses (P cond = I 2 ∙ R (on) (T J )) of CoolMOS™ and CoolSiC™ it is possi- ble to design-in a higher R DS(on) for CoolSiC™. In addition, the output charge (Q OSS ) and reverse recovery charge (Q rr ) are significantly lower. Developments in CoolMOS™ have led to the reduction of the body diode Q rr , now available as fast-diode device families CFD and CFD7. Nevertheless, this charge is still too high to achieve the very high-efficiency results possible with CoolSiC™, which has 10 times lower charge than the best fast-di- ode SJ MOSFET available on the market. Stage 3: The third stage in the example is based on the High Efficient and Reliable Inverter Concept (HERIC). During backup mode, the high DC bus voltage is convert- ed to a PWM modulated high-frequency AC waveform, which then passes through a low pass output filter to produce a sine wave output. The HERIC inverter employs addi- tional back to back switches, which operate at low frequency to de-couple the output inductor current from the input during pe- riods of the cycle when the four H-bridge switches are all off. This reduces common mode noise leakage current and EMI. During charge mode, this stage operates as a synchronous totem pole PFC boost converter able to operate in positive and negative line half-cycles to generate the high voltage DC bus, which is then converted back through stages (2) and (1) to charge the battery. 600-650 V power switches are required for the H-bridge to avoid avalanche during any The higher critical breakdown field allows a given voltage rating to be maintained while reducing the thickness of the device enabling lower on-state resistanc APRIL 2020 | www.powerelectronicsnews.com9 Next >