基于断续脉宽调制的三电平逆变器中性点电位平衡控制方法

doi:10.11985/2017.04.005

摘要/Abstract

摘要：

在中压大功率逆变器中,存在开关频率高、开关损耗大等问题。采用断续脉宽调制策略（DPWM）能降低开关频率,同时减小开关损耗。通常,传统的中性点平衡方法是将补偿电压引入到参考电压中,但是当采用DPWM调制方法时,由于开关的通断之间会存在一定的间隔,所以采用传统的平衡方法无法达到中性点平衡控制。本文首先分析了中性点不平衡的原因,其次分析了传统平衡控制方法的局限性,最后采用断续脉宽角调节控制方法。该方法既保证了低的开关频率,同时实现了中性点电压的平衡,并且没有引入额外的硬件电路和复杂的计算方法。最后采用Matlab/Simulink仿真验证了所提出的方法的有效性。

关键词: 三电平逆变器, 断续脉宽调制, 中性点电位控制

Abstract:

In a medium-voltage high-power inverter, there are problems such as high switching frequency and high switching loss. Discontinuous pulse-width modulation (DPWM) can reduce the switching frequency and the switching loss. Generally, the offset voltage is added to reference voltages in the conventional voltage balancing method. However, when using DPWM, the performance of conventional balancing method is limitary because turn-on and turn-off switching occurs at regular interval. In this paper, the causes of the imbalance of the neutral-point are analyzed at first, and then the limitations of traditional control methods are analyzed, and finally the method of adaptive control of intermittent pulse width angle is proposed. The proposed method maintains low switching losses and achieves the effective voltage balancing, without additional hardware and complex calculation. Finally the results obtained through the Matlab/Simulink simulation verify that the effectiveness of the proposed method.

Key words: Three-level inverter, discontinuous pulse width modulation, neutral-point voltage balancing

中图分类号:

TM351

刘思强,王丽梅. 基于断续脉宽调制的三电平逆变器中性点电位平衡控制方法[J]. 电气工程学报, 2017, 12(4): 27-32.

Liu Siqiang,Wang Limei. A New Discontinuous PWM Method of Three-Level Inverter for Neutral-Point Voltage Balancing Control[J]. Journal of Electrical Engineering, 2017, 12(4): 27-32.

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参考文献 12

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矢量	幅值	开关状态		中性点电流
零矢量	0	PPP OOO NNN		–
小矢量	$\frac{1}{3}U_{dc}$	P型	N型	P型	N型
		POO	ONN	I_b+I_c	I_a
		PPO	OON	I_c	I_a+I_b
		OPO	NON	I_a+I_c	I_b
		OPP	NOO	I_a	I_b+I_c
		POP	ONO	I_b	I_a+I_c
		OOP	NNO	I_a+I_b	I_c
中矢量	$\frac{\sqrt{3}}{3}U_{dc}$	PON		I_b
		OPN		I_a
		NPO		I_c
		NOP		I_b
		ONP		I_a
		PNO		I_c
大矢量	$\frac{2}{3}U_{dc}$	PNN		–
		PPN		–
		NPN		–
		NPP		–
		NNP		–
		PNP		–