Californian startup Pre-Switch has released the first data from its 200kVA soft switching inverter reference design, showing a dramatic reduction in switching losses of 90 percent.
The double pulse test data came from the Cleanwave soft-switching platform which combines the Pre-Drive3 controller board powered by the Pre-Flex FPGA, and RPG gate driver board. This allows higher switching frequencies for hard switched silicon IBGT, silicon carbide (SiC) or gallium nitride (GaN) designs with half the transistor count.
In the case of a silicon carbide EV inverter, increasing the switching frequency from 10kHz up to 100kHz or 300kHz using Cleanwave creates a near perfect sine wave without any output filter. The result is elimination of unnecessary motor iron losses and an increased motor efficiency at low torque and low RPM. Higher switching frequencies also enable higher RPM motors that are lighter and lower cost.
The company maintains that soft switching hasn't been successfully implemented for DC-AC systems with varying input voltage, temperature and load conditions. So it used Artificial Intelligence (AI) techniques to constantly adjust the relative timing of elements within the switching system required to force a resonance to offset the current and voltage wave forms to minimize the switching losses.
“Our CleanWave200 evaluation system allows customers to assess the cycle-by-cycle adaption of Pre-Switch’s AI-based soft-switching technology and explore the benefits of higher switching frequencies in their application," said Bruce Renouard, CEO of Pre-Switch. "CleanWave200 is the power block of an inverter with a PWM interface. The system bi-directionally converts 800VDC to three phase AC at power up to 200kVA with a Fsw of 100kHz and 99% efficiency.”