DC-LINK VOLTAGE BALANCING SYSTEM AND METHOD FOR MULTILEVEL CONVERTERS
First Claim
1. A control system for controlling a multilevel converter, the control system comprising:
- a differential mode current regulator for generating reference voltage command signals based on a difference between reference current command signals and actual current command signals;
a neutral point (NP) controller for determining a modified neutral point current signal in response to a DC link voltage unbalance and using the modified neutral point current signal to generate a common mode reference voltage signal; and
a PWM controller for generating switching pulses for the multilevel converter based on the reference voltage command signals and the common mode reference voltage signal.
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Accused Products
Abstract
A control system for a multilevel converter includes a differential mode current regulator, a neutral point (NP) controller and a PWM controller for generating switching pulses for the multilevel converter. The differential mode current regulator generates reference voltage command signals based on a difference between reference current command signals and actual current command signals, and the NP controller determines a modified neutral point current signal in response to a DC link voltage unbalance. The NP controller utilizes the modified neutral point current signal to generate a common mode reference voltage signal. The switching pulses are generated by the PWM controller based on the reference voltage command signals and the common mode reference voltage signal.
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Citations
20 Claims
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1. A control system for controlling a multilevel converter, the control system comprising:
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a differential mode current regulator for generating reference voltage command signals based on a difference between reference current command signals and actual current command signals; a neutral point (NP) controller for determining a modified neutral point current signal in response to a DC link voltage unbalance and using the modified neutral point current signal to generate a common mode reference voltage signal; and a PWM controller for generating switching pulses for the multilevel converter based on the reference voltage command signals and the common mode reference voltage signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of controlling a multilevel converter comprising:
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(a) generating reference voltage command signals based on a difference between reference current command signals and actual current command signals; (b) in response to a voltage unbalance on a DC link of the multi-level converter, (i) using the reference voltage command signals and reference current command signals for generating a modified neutral point current signal to compensate for the DC link voltage unbalance; (ii) using the modified neutral point current signal for generating a common mode reference voltage signal; and (iii) generating switching pulses for the multilevel converter based on summation of reference voltage command signals and the common mode reference voltage signal. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A multilevel converter comprising:
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a plurality of phase legs each having at least two inner switching devices, at least two outer switching devices, at least two clamping diodes and a split DC link; and a control system for controlling the multilevel converter comprising a differential mode current regulator for generating reference voltage command signals based on a difference between reference current command signals and actual current command signals; a neutral point (NP) controller for determining a modified neutral point current signal in response to a DC link voltage unbalance and using the modified neutral point current signal to generate; and a PWM controller for generating switching pulses for the multilevel converter based on the reference voltage command signals and the common mode reference voltage signal.
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Specification