Modulation method for a three-phase multilevel converter

Patent metadata

Field	Value
Publication number	US-10097110-B2
Application number	US-201815908825-A
Country	US
Kind code	B2
Filing date	Mar 1, 2018
Priority date	Mar 8, 2017
Publication date	Oct 9, 2018
Grant date	Oct 9, 2018

Abstract

The present invention discloses a modulation method for a three-phase multilevel converter. The modulation method comprises the following steps: generating first three-phase sinusoidal modulated wave signals by a control loop in the three-phase multilevel converter; generating second three-phase modulated wave signals by processing the first three-phase sinusoidal modulated wave signals, wherein in proximity to peak values of a line voltage of the second three-phase modulated wave signals, absolute values of any two phases are unequal; generating PWM pulse signals based on the second three-phase modulated wave signals; and generating driving signals for respective power units in the three-phase multilevel converter based on the PWM pulse signals.

First claim

What is claimed is:

1. A modulation method for a three-phase multilevel converter, comprising the following steps:
step 1 : generating first three-phase sinusoidal modulated wave signals by a control loop in the three-phase multilevel converter;
step 2 : generating second three-phase modulated wave signals by processing the first three-phase sinusoidal modulated wave signals,
wherein in proximity to peak values of a line voltage of the second three-phase modulated wave signals, absolute values of any two phases are unequal;
step 3 : generating PWM pulse signals based on the second three-phase modulated wave signals; and
step 4 : generating driving signals for respective power units in the three-phase multilevel converter based on the PWM pulse signals.

2. The modulation method according to claim 1 , wherein the step 2 further comprises:
injecting triple harmonic signals into the first three-phase sinusoidal modulated wave signals to generate the second three-phase modulated wave signals.

3. The modulation method according to claim 1 , wherein the step 3 further comprises:
step 31 : performing a carrier phase-shifted modulation on the second three-phase modulated wave signals to generate the PWM pulse signals; and
step 32 : computing differences between absolute values of every two phases in proximity to the peak values of the line voltage of the second three-phase modulated wave signals in real time, and comparing the differences between absolute values with a threshold.

4. The modulation method according to claim 3 , wherein the step 3 further comprises:
step 33 : when the differences between absolute valves of two phases are smaller than the threshold, performing a phase-shifting process on the PWM pulse signals corresponding to the two phases in one switching period respectively.

5. The modulation method according to claim 4 , wherein within the switching period, the PWM pulse signals corresponding to one of the two phases and the PWM pulse signals corresponding to the other phase are phase-shifted by opposite directions and the same time.

6. The modulation method according to claim 2 , wherein triangular carriers of the three-phase multilevel converter change within a range of −Um to Um, and expressions of the triple harmonic signals are as follows:

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Assignees

• Delta Electronics Shanghai Co

Inventors

• Chen Kai

Classifications

• H02P27/08 Primary

  with pulse width modulation · CPC title

• H02P2209/11

  Sinusoidal waveform · CPC title

• H02P29/032

  Preventing damage to the motor, e.g. setting individual current limits for different drive conditions · CPC title

• H02M7/53871 Primary

  with automatic control of output voltage or current · CPC title

• H02M1/0022

  the disturbance parameters being input voltage fluctuations · CPC title