Neutral point controller, method of controlling and rectifier system employing the controller and the method
View Patent ↗The present invention provides a neutral point controller for use with a three level rectifier. In one embodiment, the neutral point controller includes a primary drive circuit configured to provide primary drive signals for the three level rectifier thereby establishing output voltages having a common neutral point. Additionally, the neutral point controller also includes a current balancing compensator coupled to the primary drive circuit and configured to maintain the common neutral point within a predefined voltage by adjusting the primary drive signals based on a current balancing feedback signal. In an alternative embodiment, the neutral point controller further includes a duty cycle compensator coupled to the current balancing compensator and configured to maintain the common neutral point within the predefined voltage by adjusting the primary drive signals based on a direct balancing pulse width modulation signal.
1. A neutral point controller for use with a three level rectifier, comprising:
a primary drive circuit configured to provide primary drive signals for said three level rectifier thereby establishing output voltages having a common neutral point; and
a current balancing compensator coupled to said primary drive circuit and configured to maintain said common neutral point within a predefined voltage by adjusting said primary drive signals based on a current balancing feedback signal, wherein said current balancing feedback signal employs a difference between said output voltages.
2. The controller as recited in claim 1 wherein said primary drive signals employ a summation of said output voltages and a reference voltage to regulate said output voltages.
3. The controller as recited in claim 1 wherein said primary drive signals are pulse width modulation signals.
4. The controller as recited in claim 1 wherein said predefined voltage is less than about 10 volts.
5. A neutral point controller for use with a three level rectifier, comprising:
a primary drive circuit configured to provide primary drive signals for said three level rectifier thereby establishing output voltages having a common neutral point;
a current balancing compensator coupled to said primary drive circuit and configured to maintain said common neutral point within a predefined voltage by adjusting said primary drive signals based on a current balancing feedback signal; and
a duty cycle compensator coupled to said current balancing compensator and configured to maintain said common neutral point within said predefined voltage by adjusting said primary drive signals based on a direct balancing pulse width modulation signal.
6. The controller as recited in claim 5 wherein said direct balancing pulse width modulation signal provides a direct adjustment to said primary drive signals.
7. A method of controlling a neutral point voltage for use with a three level rectifier, comprising:
providing primary drive signals for said three level rectifier thereby establishing output voltages having a common neutral point; and
maintaining said common neutral point within a predefined voltage by adjusting said primary drive signals based on a current balancing feedback signal, wherein said current balancing feedback signal employs a difference between said output voltages.
8. The method as recited in claim 7 wherein said primary drive signals employ a summation of said output voltages and a reference voltage to regulate said output voltages.
9. The method as recited in claim 7 wherein said primary drive signals are pulse width modulation signals.
10. The method as recited in claim 7 wherein said predefined voltage is less than about 10 volts.
11. The method as recited in claim 7 further comprising maintaining said common neutral point within said predefined voltage by adjusting said primary drive signals based on a direct balancing pulse width modulation signal.
12. The method as recited in claim 11 , wherein said direct balancing pulse width modulation signal provides a direct adjustment to said primary drive signals.
13. A rectifier system, comprising:
a three level rectifier that employs a three phase input signal and provides output voltages with a common neutral point; and
a neutral point controller, having:
a primary drive circuit that provides primary drive signals for said three level rectifier, and
a current balancing compensator, coupled to said primary drive circuit, that maintains said common neutral point within a predefined voltage by adjusting said primary drive signals based on a current balancing feedback signal, wherein said current balancing feedback signal employs a difference between said output voltages.
14. The system as recited in claim 13 , wherein said primary drive signals employ a summation of said output voltages and a reference voltage to regulate said output voltages.
15. The system as recited in claim 13 , wherein said primary drive signals are pulse width modulation signals.
16. The system as recited in claim 13 , wherein said predefined voltage is less than about 10 volts.
17. A three level rectifier that employs a three phase input signal and provides output voltages with a common neutral point; and
a neutral point controller, having:
a primary drive circuit that provides primary drive signals for said three level rectifier
a current balancing compensator, coupled to said primary drive circuit, that maintains said common neutral point within a predefined voltage by adjusting said primary drive signals based on a current balancing feedback signal; and
a duty cycle compensator, coupled to said current balancing compensator, that maintains said common neutral point within said predefined voltage by adjusting said primary drive signals based on a direct balancing pulse width modulation signal.
18. The system as recited in claim 17 wherein said direct balancing pulse width modulation signal provides a direct adjustment to said primary drive signals.