Control system and control method

A control system for controlling a single phase induction motor with a main winding and with an auxiliary winding, the control system comprising:

• a first bidirectional switching element and a second bidirectional switching element,
• wherein the first bidirectional switching element is arranged between a phase supply input of the single phase induction motor and the main winding and wherein the second bidirectional switching element is arranged electrically parallel to the main winding,
• a controller coupled to the first bidirectional switching element and the second bidirectional switching element,
• wherein the controller is configured to control in an alternating manner, during a positive half-wave of a supply voltage of the single phase induction motor
• the first bidirectional switching element to provide a positive current to the main winding and
• the second bidirectional switching element to provide a freewheeling current path for the positive current through the main winding, and
• wherein the controller is configured to control in the alternating manner, during a negative half-wave of the supply voltage of the single phase induction motor
• the first bidirectional switching element to provide a negative current to the main winding and
• the second bidirectional switching element to provide the freewheeling current path for the negative current through the main winding,
• further comprising
• a current sensor coupled to the controller and configured to sense an input current to the single phase induction motor at the phase supply input, wherein the controller is configured to drive the first bidirectional switching element and the second bidirectional switching element based on the sensed current,
• wherein the controller is configured to control the first bidirectional switching element and the second bidirectional switching element in the alternating manner based on a PWM scheme, wherein the controller is configured to determine a duty cycle for the PWM scheme based on the input current,
• wherein the controller comprises an integral controller configured for determining the duty cycle based on a difference between a reference current value and the input current,
• wherein the controller comprises a reference value determination unit configured to determine the reference current value based on a fixed current value and a variable feedback current value, wherein the controller is configured to determine the variable feedback current value based on the duty cycle,
• wherein the reference value determination unit is configured to determine the reference current value by adding the fixed current value to the variable feedback current value.