Three-phase resonant converter and method of controlling the same

A three-phase resonant converter, comprising:

• a three-phase transformer, comprising three primary-side windings and three secondary-side windings,
• an input bridge arm assembly, comprising a first input switch arm, a second input switch arm, and a third input switch arms respectively coupled to the three primary-side windings, wherein the first input switch arm comprises a first upper switch and a first lower switch, the second input switch arm comprises a second upper switch and a second lower switch, and the third input switch arm comprises a third upper switch and a third lower switch, and
• an output bridge arm assembly, comprising a first output synchronous rectification switch arm, a second output synchronous rectification switch arm, and a third output synchronous rectification switch arm respectively coupled to the three secondary-side windings, wherein the first output synchronous rectification switch arm comprises a first upper rectification switch and a first lower rectification switch, the second output synchronous rectification switch arm comprises a second upper rectification switch and a second lower rectification switch, and the third output synchronous rectification switch arm comprises a third upper rectification switch and a third lower rectification switch, and
• a current balance controller, configured to receive a first current, a second current, and a third current, and calculate a first phase angle difference and a second phase angle difference according to peak values, average values, or root-mean-square values of the first current, the second current, and the third current,
• wherein the first current is a current flowing from a command node between the first upper switch and the first lower switch to the three-phase transformer, the second current is a current flowing from a command node between the second upper switch and the second lower switch to the three-phase transformer, and the third current is a current flowing from a command node between the third upper switch and the third lower switch to the three-phase transformer,
• wherein the control unit maintains an output voltage of the resonant converter to be higher than a voltage threshold by configuring the first upper rectification switch to be turned on with a first phase angle leading to the first upper switch, the second upper rectification switch to be turned on with a second phase angle leading to the second upper switch, and the third upper rectification switch to be turned on with a third phase angle leading to the third upper switch;
• and configuring the first lower rectification switch to be turned on with the first phase angle leading to the first lower switch, the second lower rectification switch to be turned on with the second phase angle leading to the second lower switch, and the third lower rectification switch to be turned on with the third phase angle leading to the third lower switch;
• wherein the second phase angle is equal to the first phase angle plus the first phase angle difference, and the third phase angle is equal to the first phase angle plus the second phase angle difference.