Performance Analysis of Carrier-Based Discontinuous PWM Method for Vienna Rectifiers With Neutral-Point Voltage Balance

The nongenerative-boost type rectifier, which is called the Vienna rectifier, is advantageous in terms of efficiency and current total harmonic distortion. Therefore, the Vienna rectifier is used in grid-connected applications such as telecommunication systems and wind turbine systems. Owing to the structural characteristics of the Vienna rectifier, various switching methods exist. Among these methods, a carrier-based discontinuous pulse-width modulation (CB-DPWM) method guarantees high efficiency compared to continuous pulse-width modulation methods; moreover, it is simple compared to a DPWM method based on space vectors. In this paper, the performance of the CB-DPWM method, its applicable region depending on the power factor and modulation index (M_a), and its efficiency are analyzed in detail. Then, based on the analysis, a neutral-point voltage balancing method for the CB-DPWM method is proposed. The effectiveness and performance of the proposed neutral-point voltage balancing method are verified by simulation and experiment.

I. Introduction

The Vienna rectifier, which is a grid-connected voltage-source pulse-width modulation (PWM) rectifier of the nongenerative-boost type, has advantages of efficiency and low total harmonic distortion of input currents [1]–[8] . In the past, the Vienna rectifier was mostly used in telecommunication power systems which operate at unity power factor (pf). Recently, it has been used in a wide range of applications such as telecommunication power systems [4], wind turbine systems [5], and pf correction systems [6].