Improving the Design of Automotive Air Conditioning Compressors by Predicting the Minimum Engagement Voltage of Electromagnetic Clutches

In order to insure passengers’ comfort, automotive air conditioning compressors are designed to be operational in case of low battery voltage. However, the “minimum engagement voltage” of compressors is mostly driven by designers’ know-how and rely extensively on laboratory tests, which can lead to two issues: Costly design modifications if problems are detected too late in the validation phase and the necessity to perform several design iterations before reaching the desired target. This paper presents the benefit of predicting the minimum engagement voltage where both of these drawbacks can be avoided, leading to a more robust design process.

The method was tested on an electromagnetic clutch whose purpose is to engage the compressor when the air conditioning is turned on by passengers. The magnetic field generated by the clutch was estimated using an electromagnetic simulation software. Coil design parameters, materials magnetic properties, clutch assembly geometry and air gaps were all taken into account using 3D modeling. Finally, experimental tests were conducted, and the tool predicted the minimum engagement voltage with an accuracy of ±0.3V.