Electric Compressor Drive with Integrated Electronics for 42 V Automotive HVAC Systems

The electrical power demand in automobiles is rising steadily, especially in luxury vehicles, due to new electrical systems that enhance passenger comfort and safety. The present 14 V bus and Lundell based alternators are being pushed to their limits to meet these higher loads. The 42 V or higher voltage bus system in future automobiles enables a number of new features that require high power including electric compressors for HVAC. Electric compressors have advantages of low refrigerant emissions, flexible packaging and an efficient variable speed operation. These are intended mainly for “stop and go” vehicles with engine shuts-off during stops to improve fuel economy or for vehicles equipped with auxiliary power unit such as fuel cell. A cost effective semi-integrated position sensorless permanent magnet brushless motor has been designed, built and tested over the wide speed range with overall system efficiency of 85% over the significant portion of the operating range. The key issues of integration of electronics with compressor for compact packaging, thermal management, EMI abatement and performance test results of the drive are discussed.