Three phase, 380V supply is changed into 540V DC (typically) using a Vienna rectifier. This DC is then chopped to provide the required frequencies to drive and control the motor. The higher the frequency, the faster the motor runs.

Chopping means switching the DC bus on and off, making rectangular waveforms called Pulse Width Modulation or PWM.

As the width of these rectangular waves is varied, the power delivered increases or decreases.  This digital on/off signal then either has to be averaged to a sine wave in a big external filter that is expensive and bulky. Or, in cheaper systems that don't have the filter, connected directly to the motor, where these high voltage, high speed transients degrade the bearings, the insulation and heat up the motor, wasting power and reducing the life of the motor. 

With our approach, the high voltage PWM is filtered inside a VFD implemented with our modules using the WhisperGaN construction system and only pure sinewaves leave the module. Thus, no big, expensive, external filter is needed to generate sinewaves for the motor and the connected motor's lifespan is not degraded by a VFD that is based on our breakthrough technology.

Energy is lost on the rise and fall of each transition from off to on or on to off. Shorten the time that this takes and less energy is lost.

The smaller area under Vds/IDS curves results in lower power being dissipated so faster switching results in less loss.

This is dependent on the frequency that the controlling transistors operate at. To be precise, the majority of energy loss occurs when the transistor is neither on nor off. 

GaN transistors are capable of switching in 1-2 ns, as opposed to 20-50ns for Si and SiC transistors.  Thus, GaNs are in this high energy loss region for almost no time at all and, consequently, they waste very little energy chopping the DC up into variable frequency AC to drive the motor at different speeds. This is the key to QPT being able to reduce energy wastage in a VFD by round 80%.