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10KW power inverter and motor controller employs SiC MOSFETs under Zynq control

Xilinx Employee
Xilinx Employee
0 0 48.9K

Multilevel power converters employ more than two voltage levels to achieve smoother and less distorted ac-to-dc, dc-to-ac, and dc-to-dc power conversion and motor control. QDESYS has developed a laptop-sized, 10KW, 3-level power inverter and motoro controller based on twelve SiC (silicon-carbide) MOSFETs. The design employs a Zynq-based Avnet MicroZed or PicoZed SOM (System on Module) to control the SiC power MOSFETs using RPFM (regenerative pulse frequency modulation) and to provide system communications with the outside world. (For more technical information about RPFM, see Dr. Giulio Corradi’s EDN article “FPGA high efficiency, low noise pulse frequency space vector modulation--Part I” and “FPGA high efficiency, low noise pulse frequency vector modulation—Part II.” PDFs of these two articles are attached below.)


Here’s a block diagram of the QDESYS design:



Qdesys 3-Level Power Inverter.jpg



Here’s a photo of the resulting system including the QDESYS power-inverter carrier card, the Avnet MicroZed SOM, and an ISM Networking FMC Module.



Qdesys 3-Level Power Inverter Board Photo.jpg


SiC MOSFETs can switch higher voltages and currents at higher temperatures (175°C), have a larger band-gap and high voltage breakdown (1200V), and exhibit fast switching capabilities that can deliver better performance for power inverters when compared to IGBTs. The 3-level power inverter design mitigates motor-control issues caused by long power cables between the controller and the motor or load by employing smaller voltage steps. The smaller voltage steps also reduce voltage surges and curb rise times at the motor terminals. The waveform output is cleaner because the effective switching frequency of a 3-level power inverter is twice the actual switching frequency. Here’s a comparison of the two waveforms for illustration:



2-level versus 3-level power inverter waveforms.jpg



For more information about the QDESYS SiC power inverter and motor controller, click here. For a complete presentation about this technology, click here.