A Neutral-Point Voltage Balance Controller for the Equivalent SVPWM Strategy of NPC Three-Level Inverters

Abstract

Based on the space vector pulse width modulation (SVPWM) theory, this paper realizes an easier SVPWM strategy, which is equivalently implemented by CBSPWM with zero-sequence voltage injection. The traditional SVPWM strategy has no effect on controlling the neutral-point voltage balance. In order to solve the neutral-point voltage unbalance problem for neutral-point-clamped (NPC) three-level inverters, this paper proposes a neutral-point voltage balance controller. The proposed controller realizes controlling the neutral-point voltage balance by dynamically calculating the offset superimposed to the three-phase modulation waves of an equivalent SVPWM strategy. Compared with the traditional SVPWM strategy, the proposed neutral-point voltage balance controller has a strong ability to balance the neutral-point voltage, has good steady-state performance, improves the output waveforms quality and is easy for digital implementation. An experiment has been carried out on a NPC three-level inverter prototype based on a digital signal processor-complex programmable logic device (DSP-CPLD). The obtained experimental results verify the effectiveness of the proposed neutral-point voltage balance controller.

Implementation Decentralized Space Vector PWM Method for Multilevel Multiphase Converters

“…The SVPWM method is used as a switching pulse modulation algorithm in 3-phase [14], 5phase [15], 6-phase [13], dual-six-phase [16], and dual-threephase applications [17]. In addition to the main task of providing flexible switching solutions for insulated gate bipolar transistor (IGBT) switches, research on the SVPWM method focuses on solving the following problems: voltage balance of capacitors in a multilevel neutral point clamped (NPC) inverter model [18], balance voltage between modules in multilevel multiphase power converters [19], reduction of common mode voltage [20], reduction of total harmonic distortion (THD) [15], reducing switching loss, solving the problem when the power converter works in over-modulation. Recently, the core value of the SVPWM method has been enhanced by finding a general implementation for multilevel multiphase power converters.…”

Análise Do Conteúdo Harmônico De Corrente De Um Sistema Fotovoltaico Conectado À Rede Com Inversores Convencional E NPC Trifásicos Usando SPWM E SVPWM

“…O segundo objetivo principal deste artigo é validar as melhorias apontadas por Lyu et al (2016), comprovando com os resultados das simulações no Simulink ® que a utilização da técnica de modulação Space Vector (SVPWM) permite reduzir os níveis de THDi e a tensão necessária no barramento CC, quando comparados com os resultados obtidos com a modulação senoidal (SPWM). Além disso, comprovando também que, por meio da utilização da topologia de inversor de três níveis NPC, é possível reduzir os níveis de THDi obtidos com inversores convencionais de dois níveis.…”