High frequency excitation system
A power module is adapted to be connected to a voltage source and to supply power to a load. The power module includes a power transistor; and a gate controller for driving the power transistor. The gate controller includes a gate transformer, and an impulse generator that extends a negative drive phase of a gate voltage to the power transistor relative to a positive drive phase of the gate voltage to the power transistor.
1. A power module adapted to be connected to a voltage source and to supply power to a load, the power module comprising:
a power transistor; and
a gate controller for driving the power transistor;
wherein the gate controller comprises:
a gate transformer, and
an impulse generator that extends a negative drive phase of a gate voltage to the power transistor relative to a positive drive phase of the gate voltage to the power transistor.
2. The power module of claim 1 , wherein the impulse generator comprises:
a capacitor in parallel with an input capacitance of the power transistor, and
a switching element.
3. The power module of claim 1 , wherein the gate transformer includes a low frequency ferrite.
4. A method of driving a power module, the method comprising:
connecting the power module to a voltage source;
supplying power from the power module to a load;
controlling a gate of at least one power transistor of the power module with a gate controller that includes a gate transformer and an impulse generator, the gate transformer providing an input signal having a duty cycle to the impulse generator; and
creating pulses with the impulse generator to drive the gate of the at least one power transistor with a reduced duty cycle relative to the duty of the input signal.
5. The method of claim 4 , further comprising generating a symmetrical square-wave voltage that is applied to the gate transformer.
6. The method of claim 4 , wherein creating the pulses includes using a switching element and a capacitor.
7. A method of driving a power module, the method comprising:
connecting the power module to a voltage source;
supplying power from the power module to a load;
controlling a gate of at least one power transistor of the power module with a gate controller that includes a gate transformer and an impulse generator;
creating pulses with the impulse generator to drive the gate of the at least one power transistor with a gate voltage; and
extending a negative drive phase of the gate voltage relative to a positive drive phase.
8. The method of claim 7 , further comprising reducing the amplitude of the negative drive voltage.
9. The method of claim 7 , further comprising generating a symmetrical square-wave voltage that is applied to the gate transformer.
10. The method of claim 9 , further comprising generating the symmetrical square-wave voltage with a frequency that is close to a self resonance of a resonant circuit formed by an input capacitance of the at least one power transistor and a leakage inductance of the gate transformer.
11. The method of claim 7 , wherein creating the pulses includes using a switching element and a capacitor.
12. The method of claim 11 , wherein creating the pulses includes using a body diode of the switching element.
13. A method of driving a power module, the method comprising:
connecting the power module to a voltage source;
supplying power from the power module to a load;
controlling a gate of at least one power transistor of the power module with a gate controller that includes a gate transformer and an impulse generator; and
creating pulses with the impulse generator to drive the gate of the at least one power transistor with a reduced duty cycle,
wherein creating the pulses includes using a switching element and a capacitor.