POWER FEATURE
is significantly faster. Pre-Flex learns, remembers, and adjusts in-system, on a cycle-by-cycle basis, ensuring clean and accurate soft-switching, despite changing parameters. The result is the reduction of switching losses by around 80 per cent in IGBTs, and up to 95 per cent in SiC and GaN MOSFETs, enabling 5-20x faster switching frequencies. The architecture also enables reduced dV/dt (dU/dt), common mode noise that is known to cause damage to motor bearings. This effective elimination of switching losses and reduced dV/dt opens the door for system- level improvements in cost, system efficiency, power density and motor reliability. There are multiple dimensions to Pre- Switch’s AI that are needed to enable zero voltage switching (ZVS) or zero current switching (ZCS) in applications where changing duty cycles, loads, input voltage, system and device temperature, changing device tolerance and device degradations are all compensated for to enable a successfully optimised, forced
“Pre-Flex learns, remembers, and adjusts in-system, on a cycle-by-cycle basis, ensuring clean and accurate soft-switching, despite changing parameters”
resonant switching event. The capture of data from each switching cycle is then stored, and the results are compared to the expected result. If the results are not optimal, specific timing adjustments are made to ensure the next cycle will be fully optimised. If the results are outside of the predicted results, the error is flagged, and the system is shut down. The result is consistently reliable soft-switching, even with wide input, system and load variability. Pre-Flex also uses its understanding of the system parameters to reduce the amount of dead time needed and increase
system safety. The Pre-Switch solution,
including the Pre-Drive3 controller board, powered by the Pre-Flex
FPGA and RPG gate driver board, can significantly reduce the cost of solar inverters. The two-stage architecture delivers the same switching loss performance and reduced THD as a five- level design, resulting in reduced cost, control complexity and BOM count. Also, the Pre-Switch technology means that switching frequencies can be run 5-20x faster, enabling the simplification and
size reduction of inverters and filters used in renewable energy systems, further allowing energy to be put back into the grid easily and efficiently. The faster switching frequencies additionally offer improved motor efficiencies for industrial motors and EVs. The Pre-Switch soft-switching
platform enables a doubling of power output for a typical inverter, or an increase in switching speed by a factor of up to 20 times. Previously, soft-switching has never been successfully implemented for DC/AC systems. However, Pre-Switch has overcome the challenges by using AI to adjust the relative timing of elements within the switching system required to force a resonance to offset the current and voltage wave forms. The architecture also allows the grid tie filter size to be reduced by up to 66.67 per cent for IGBT systems, and by up to 80 per cent for SiC MOSFETs. That is a noticeable advantage, not only in solar energy generation system size, but also materials and shipping cost savings.
Pre-Switch
www.pre-switch.com
/ ELECTRONICS
ELECTRONICS | DECEMBER/JANUARY 2020
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