STMicroelectronics has just announced an agreement to supply its 3rd generation silicon-carbide (SiC) planar MOSFETs for the e-compressor controllers from ZINSIGHT Technology, a Chinese high-tech company specializing in SiC power modules and advanced electric power conversion systems, used in “new energy vehicles” (NEVs), also dubbed EVs or BEVs outside China.
These high-performance controllers exploit the increased efficiency allowed by SiC MOSFET inverters and offer several benefits contributing to an EV’s extended driving range, between 5 to 10 km (for a medium-size EV model with battery capacity from 60 kWh to 90 kWh) that is particularly beneficial in the summer and winter, under extreme temperatures.
Electric motor drives and batteries are very efficient, so they produce very little waste heat. And that’s why almost all the energy from the batteries is used for driving. But when the passengers turn on the heating knob, the energy used gets subtracted from the miles that can be driven. That means driving range can fall considerably adding range anxiety to that of driving in icy roads.
Catering to the fast-growing Chinese market
ZINSIGHT Technology (Shanghai) Co., Ltd. is a high-tech company focusing on SiC-based devices and advanced EV traction systems. With more than 10 years of R&D experience in SiC power modules and EV traction systems, ZINSIGHT is offering the SiCTex series of advanced SiC-based powertrain systems, and ZiPACK series of high-performance SiC power modules, used in EVs, hydrogen fuel-cell battery systems, air-conditioning compressor drives, as well as industrial drives.
ZINSIGHT is the first Chinese company to have designed ST’s SiC MOSFETs to boost the e-compressor performance. It is also the world’s mass-producer of SiC-based e-compressor controllers for air-conditioning (AC) running on 400V, 800V, and 1,000V bus platforms, delivering a significant number of units by the end of 2023. Its unique compact design allows the e-compressor controller to be used across a wide range of vehicles, from passenger sedans and vans to buses and heavy-duty trucks.
Reduced installation space requirements are allowed by proper refrigerant cooling of the compressor motor and advanced electronic circuitry. Customers served by ZINSIGHT are, among others, Xiaomi, BYD, GAC Motor, Changan EV, CRRC (China Railway Rolling Stock Corporation), and more.
E-compressors vs. mechanical compressors
The e-compressor is part of the HVAC system in an electrical vehicle, as Figure 1 shows. E-compressors adopted in EVs or hybrid platforms (HEV) for air-conditioning purposes differ somehow from those used in internal combustion engine (ICE) vehicles.
First of all, conventional compressors are powered mechanically using an ad-hoc drive belt from the crankshaft, whereas e-compressors are based on electric motor drives. When it comes to their function, both are primarily designed to provide the vehicle’s passengers and driver with the most pleasant interior environment, but the AC system in EVs or HEVs also fulfills a very crucial function, that of cooling the battery pack equipping the vehicle and ensuring that the operating temperature stays within the normal range.
This happens during both car operation and recharging. The battery of an EV also performs less efficiently in freezing weather for the simple reason that batteries operate by exploiting chemical reactions with electrons and ions moving in both directions. When it gets too cold, as is happening today in northern America, all sorts of chemical reactions slow down, including those taking place in a battery.
While an AC system installed in ICE cars can fail without impacting the vehicle’s running, such occurrence in EVs is deleterious because the battery temperature is no longer controllable. This is why the e-compressor is an integral and essential part in the vehicle’s set of energy converters.
Operation of an e-compressor
A general e-compressor consists of the following elements: compressor, motor, inverter, condenser, expansion valve, evaporator, and chiller. The compressor draws in, compresses, and discharges refrigerant. The motor is normally a DC brushless type with rotor permanent magnets and a field coil in the stator. The inverter transforms DC from the HV battery into AC to feed the motor. The internal electric motor of the e-compressor enables the AC to keep functioning, even when the hybrid or electric motor is idling or turned off. The operation principle is described below.
The signal incorporating the compressor’s rotation speed is sent to the inverter via the control unit’s MCU (Figure 1) to set the right compressor speed. Clearly, by controlling the electric compressor speed, we can also control the energy consumption The condenser serves to cool and liquefy the gaseous refrigerant by the ambient temperature. The liquid refrigerant then goes into the expansion valve which reduces its pressure and temperature. The liquid refrigerant flows through the evaporator and the chiller, where evaporation occurs.
To cool the car interior, heat is taken away from the air flowing from the evaporator into the cabin. The refrigerant and battery cooling circuits are connected via the chiller. This enables the transfer of heat from the battery coolant to the refrigerant circuit. The vaporized refrigerant returns to the compressor, restarting the cycle.
ST’s 3rd generation of SiC MOSFETs
ST is well renowned as a world leader in SiC technology, having been the first supplier to have developed products tailored to the demanding Automotive market. ST’s advanced third-generation 1,200V SiC MOSFET ensures industry-leading process stability and performance, efficiency, and reliability. ZINSIGHT’s controllers with unique cooling technology and advanced thermal protection design, coupled with the latest ST’s SiC MOSFET technology, deliver better thermal management for NEVs, and improved NVH (noise, vibration, and harshness), at a competitive cost.
“Leveraging ST’s leadership in SiC technology and ZINSIGHT’s innovative design and state-of-the-art process, our cooperation with ST is accelerating innovation in e-compressor controller design, achieving breakthroughs in performance, efficiency, and mileage,” said Doctor Jingkui SHI, President of ZINSIGHT.
“ST’s SiC technology has been widely adopted in onboard chargers, traction inverters, and DC-DC converters for NEVs. Now, our SiC technology is enabling ZINSIGHT’s first-of-its-kind EV e-compressor controller”, explained Henry CAO, Executive Vice President of Sales & Marketing, China Region, STMicroelectronics.
About US
Heisener Electronic is a famous international One Stop Purchasing Service Provider of Electronic Components. Based on the concept of Customer-orientation and Innovation, a good process control system, professional management team, advanced inventory management technology, we can provide one-stop electronic component supporting services that Heisener is the preferred partner for all the enterprises and research institutions.
