The paper starts with a general introduction to balanced automotive actuator designs and then reviews some important aspects and potential pitfalls related to stepper motor actuators. It is shown how these items can be addressed by means of advanced stepper motor driver technologies including sensorless operation and resonance characterization. Then the operation of an automotive climate control system and its main components is discussed, including evaporator and expansion valve. It is explained that accurate control of refrigerant flow by the expansion valve is a key element to improve the HVAC efficiency. The current mechanical design of expansion valves does not provide optimal control in all circumstances. As an alternative, the operation of an electro-mechanic expansion valve is explained and it is shown how an expansion valve equipped with a linear stepper motor and a LIN stepper motor driver can bring a balanced solution towards better fuel-economy in HVAC systems.
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