QPT uses AI to boost GaN performance to 20MHz
Cambridge startup QPT has developed designs that allow power engineers to make use of the full frequency of gallium nitride (GaN) devices.
The company has designed an ASIC as a driver as well as module designs with a 650V GaN chip from GaN Systems and run up to 20MHz. These can be combined for popular topologies for machine motor drives. The company is also looking to develop its own GaN power transistors.
The key is using AI to model the microwave performance and parasitic resistances of the packaging and boards.
“We use teraflops of processing on GPUs to try simulations, and that is the perfect area for AI. We have the first one that works and is practical and over time we want to spend funds to hone this,” founder and CEO Rob Gwynne tells Nick Flaherty at eeNews Europe.
“We feel this is an enabling technology to solve the problems that power engineers need to in order to use GaN,” he said.
“This is an absolutely colossal problem – we had to come up with nine patents to get the thermal energy out without creating the RF parastics from all the metal that couples to the rest of the circuit,” he said. “So you need microwave expertise up to GHz because of the edge speeds and if you don’t properly manage that with picohenry level interconnect and correct impedance matching it basically goes bang. That takes months of EM analysis of designs and this is outside the expertise of the power engineers.”
The first generation module is 30mm x 30mm x 18mm and this is for proof of concept, built at a lab in Portugal. Then there’s an embedded PCB with discrete components for the drive, then the company plans to integrate the ASIC die. The second generation design developed in parallel will be 15mm x 15mm x 5mm.
“The modules are built together on a plate and there’s a faraday cage on the top so there is nothing conducted and nothing radiated, so we can pre-qualify the system, so it will be easier for customers to qualify,” said Gwyne. “We do have exotic materials such as AlN but the key is as you add the metal you need to and do the GHz analysis to work out the coupling, so you need complex geometry that is developed iteratively. We also have other patents on parts of the circuitry, the geometry of the packaging and how it handles pressure and relieves stress.”
“The really beautiful thing for us because we can operate in the 650V regime we can do robotics HVAC, heat pumps, motors up to 500kW for EVs, so this maps onto all these different markets. The Gen1 module is designed to work with PWM so they can use existing controller chips, so that’s up to 2MHz with the TI C2000 but the drive technology works up to 20 to 30MHz so you can reduce the size of the converter tremendously,” he said.