An integrated 42-V drive design for automobile loads with a low-distortion overmodulation strategy

This paper (also presented at [27]) presents an integrated design approach to small drives for emerging 42-V automotive systems. The emphasis is on motors for ancillary loads. The final result offers a simple and low cost solution with high efficiency and high power density. Motor and inverter designs are combined to gain advantages in power factor and operating range. A near-minimum-distortion method is introduced for the overmodulation regime to improve power factor without sacrificing harmonic performance. The design is addressed in several steps: integration of the induction motor into a 42-V environment, selection of the inverter modulation scheme, and final system integration. The proposed system consists of an induction motor wound for the proper voltage range and driven by an inverter. The inverter is used partly in the overmodulation regime when bus voltage is low. A signal is formed based on triangle injection to minimize distortion. Some alternative modulation approaches are also analyzed and compared with the proposed solution. Experimental results confirm that a low-distortion overmodulation approach can be implemented successfully.