High voltage generator and control methods thereof

A method for controlling a high voltage generator, the high voltage generator comprising:

• an inverter bridge, the inverter bridge comprising a first bridge leg and a second bridge leg, the first bridge leg and the second bridge leg being coupled in parallel, and the first bridge leg or the second bridge leg comprising two or more switch transistors distributed in series;
• a first resonant branch, the first resonant branch being coupled with the first bridge leg;
• a transformer comprising a primary side winding and a secondary side winding, the primary side winding and the first resonant branch being coupled in series, and the primary side winding being coupled with the second bridge leg;
• a second resonant branch, the second resonant branch being coupled in parallel to the primary side winding or the secondary side winding of the transformer;
• a rectifier circuit, the rectifier circuit being coupled with the secondary side winding of the transformer for providing output voltage to an X-ray generating device;
• the method comprising:
• controlling the phase relationship between the bridge leg voltage and the output current of the inverter bridge to control a frequency of a driving signal of the switch transistors of the inverter bridge.

A high voltage generator, comprising:

• an inverter circuit coupled to receive a direct-current (DC) input voltage;
• a resonant circuit coupled to the inverter circuit;
• a transformer coupled to the resonant circuit and also coupled to provide a high voltage output to a high voltage device;
• and
• a phase control circuit coupled to receive a voltage across and a current through the resonant circuit and also coupled to the inverter circuit, wherein the phase control circuit generates control signals to drive the inverter circuit, and wherein the control signals drive the inverter circuit to keep the resonant circuit operating in an inductive region.