Patent ID: 8547053

Claim:
An alternating current chopper circuit with low noise, comprising: a switching circuit having a control switching unit, wherein the control switching unit turns on or turns off according to a control signal sent by a drive controller; a first freewheel circuit connected electrically to the switching circuit and a load, the first freewheel circuit having a first switching unit and a first freewheeling unit, wherein the first freewheeling unit is a first transformer with a primary winding thereof connected to a first path of the switching circuit in series, and a secondary winding thereof connected to a first switch control end of the first switching unit; and a second freewheel circuit connected electrically to the switching circuit and the load, the second freewheel circuit having a second switching unit and a second freewheeling unit, wherein the second freewheeling unit is a second transformer having a primary winding thereof connected to a second path of the switching circuit in series, and a secondary winding thereof connected to a second switch control end of the second switching unit; wherein when the control switching unit is turned off, the first freewheeling unit turns on the first switching unit, or the second freewheeling unit turns on the second switching unit, for providing a current-conducting path to the load to maintain a continuous current flow; wherein the first freewheel circuit further comprises a first one-way freewheeling unit connected to the first switching unit in series, and wherein the second freewheel circuit further comprises a second one-way freewheeling unit connected to the second switching unit in series.