MOTOR CONTROL SYSTEMS

We describe a control system for a refrigerator compressor, the refrigerator compressor comprising an induction motor having a main winding and a starting/boost winding, the motor being energised from a single phase of an ac mains power supply, the control system comprising: an electronic controller having a power supply derived from said ac mains power supply; a current/voltage sense signal input coupled to said electronic controller to input a signal dependent on a current drawn by said motor or a voltage induced in a winding of said motor; a first controllable switch having a control connection coupled to said electronic controller to control application of power from said ac mains power supply to said main winding; a second controllable switch having a control connection coupled to said electronic controller to control application of power from said ac mains power supply to said starting/boost winding; and a temperature sense input coupled to said electronic controller to receive a temperature sense signal sensing a temperature of a cooled zone of a refrigerator; wherein said electronic controller is configured to control said first and second controllable switches responsive to both said current sense signal and said temperature sense signal to control: i) starting/boost of said compressor; ii) running of said compressor to control said temperature of said cooled zone towards a target temperature value; and, optionally, iii) an average energy consumption of said compressor.