Variable capacity drive circuit for a linear compressor in a refrigeration appliance

A method for operating a variable capacity drive circuit of a compressor, the variable capacity drive circuit having at least, a first four-quadrant switch, a second four-quadrant switch, and a motor, the method comprising:

• operating the first and second four-quadrant switches in a first state in which the first four-quadrant switch is closed and the second four-quadrant switch is open, wherein, in the first state, a voltage seen by the motor is equal to an alternating current (AC) line voltage;
• operating the first and second four-quadrant switches in a second state in which the first four-quadrant switch is open and the second four-quadrant switch is closed, wherein, in the second state, the voltage seen by the motor is to zero;
• providing a positive firing angle and a negative firing angle, the positive and negative firing angles defining when the first and second four-quadrant switches are operated in each of the first and second states;
• and
• transitioning between the first state and the second state using the positive and negative firing angles at a switching frequency determined by the AC line voltage so as to control a percentage of voltage being applied to the compressor for a positive half-cycle and a negative half-cycle.