This article describes a semiintegrated permanent-magnet (PM) brushless drive for a 42-V electric compressor for automotive heating, ventilation, and air conditioning (HVAC). Electric compressors have the advantages of low refrigerant emissions, flexible packaging, and efficient variable-speed operation. These are intended for vehicles where the engine shuts off during stops, as in "stop and go" (starter generator), or for vehicles with auxiliary power units (fuel cells). A low-cost, semiintegrated position sensorless motor controller has been designed, build and tested over a wide speed range with overall system efficiencies of 85% or more over a significant portion of its operating range. Issues related to sensorless operation, packaging and thermal management, EMI abatement and performance of the drive are discussed.