AC compressor test bench takes e-car restrictions in account

May 25, 2011 // By Christoph Hammerschmidt
In order to meet the specific challenges that electric driving creates for air conditioning technologies, IPETRONIK Environmental Testing has developed a compact compressor test bench to comfortably run standard test cycles for electrically driven refrigerant compressors, as they are commonly used for mechanically driven refrigerant compressors.

Electric and hybrid vehicles present entirely new challenges for air conditioning technology, because A/C comfort can directly affect the driving range. The series production of electric refrigerant compressors for these vehicle types requires an extended testing process, including includes performance and durability tests under realistic conditions for development, as well as testing for quality management. At the Automotive Test Expo in Stuttgart, IPETRONIK introduced a compressor test bench which takes in account the characteristic restrictions and challenges for electric hybrid electric vehicles.

This compressor test bench features a compact design that requires just three square meters of floor space for installation. It consists of a temperature-controlled, heat-insulated test cell for the compressor, a compressor drive unit with adjustable rotational speed for mechanical compressors, secondary brine circuits for the condenser and evaporator as well as supply devices. The test bench is configured for operation with environmentally friendly 1234yf refrigerant. Its control circuits and sensor technology include the following elements: condensation pressure and temperature, suction pressure and temperature, pressure and temperature at the expansion valve as well as at the crankcase (mechanical compressor), drive torque (mechanical compressor), ambient temperature for the compressor, superheat and subcooling, refrigerant mass flow, evaporator inlet pressure and much more.

The maximum capacity is 9 kW for the evaporator and 25 kW for the condenser. The temperature range for the compressor environment extends from +10 ° C to +120 ° C. The voltage on the compressor ranges from 120 V to 400 V. It is possible to test compressors with a refrigerant mass flow of up to 400 kg/h. Additional design features include a maximum compressor drive torque of 40 Nm and superheat control from 5 K to 45 K. The suction pressure ranges between 2 bar and 6 bar, and the condensation pressure between 12 bar and 25 bar. For electric compressors, communications are accomplished via LIN/CAN. Typical test applications include VDA, high/low temperature tests, Raffertests as