Common-Mode Voltage Reduction and Neutral Point Voltage Balance Modulation Technology of Quasi-Z-Source T-Type Three-Level Inverter

Abstract

The quasi-Z-source T-type inverter is a new type of three-level inverter. Compared with other three-level inverters, the quasi-z-source T-type inverter is characterized by its fault tolerance capability and boost capability. In the inverter, the modulation strategy greatly affects the performance. Aiming at the problems in three-level inverters such as excessive common-mode voltage and unbalanced neutral point potential, a space vector pulse width modulation (SVPWM) for a quasi-z-source T-type three-level inverter based via line voltage coordinate is proposed in this paper. The main research work and achievements of this paper include: (1) based on the existing research results, an SVPWM modulation strategy for the quasi-Z-source T-type inverter is proposed. The modulation method proposed by this paper can effectively reduce the common-mode voltage and balance the neutral point voltage. (2) This paper analyzes the principle of the line voltage coordinate system and makes some modifications to the line voltage coordinate system so that the proposed modulation scheme can be applied to the line voltage coordinate system. Compared with the traditional αβ coordinate system, the SVPWM algorithm in the line voltage coordinate system has the characteristic of simple calculation. The simulation and experiment results show that the control method has good performance under the conditions of dynamic response and imbalance.

Improved Carrier-Based Modulation for the Single-Phase T-Type qZ Source Inverter

“…The implementation of impedance source networks in multilevel inverters has also been quite successful. This is the case for the multilevel quasi-Z source (qZS) inverter, which employs well known topologies such as the neutral point clamped (NPC) or the T-Type [19][20][21][22][23][24]. This can be verified by several proposals for its use in renewable generators and other fault-tolerant applications.…”

A New Control for Improving the Power Quality Generated by a Three-Level T-Type Inverter

“…The control strategy involves detecting harmonics, calculating the reference compensating current waveform, and generating the compensating current waveform accordingly [24]. Different modulation strategies, such as space vector modulation (SVM) [25], the PWM technique [26], the neural SVM technique [27], neural PWM [28], and the modified SVM technique [29], can be used to generate control pulses in the IGBTs of the three-level inverter. These strategies are of great importance in improving the quality of the current and in reducing the cost and complexity of the systems.…”

An Improved Overmodulation Strategy for a Three-Level NPC Inverter Considering Neutral-Point Voltage Balance and Common-Mode Voltage Suppression

“…Shaft voltage and bearing current will be generated by the common-mode voltage (CMV), which may destroy the motor insulation in motor drive applications and increase the leakage current in the distributed generation applications [22][23][24][25]. Virtual space vector PWM (VSVPWM) provides a new idea for the NP voltage control and the CMV suppression [26][27][28][29][30][31][32][33]. A novel VSVPWM considering NP voltage balance and CMV suppression is proposed in [23].…”

“…In [29], a switched-capacitor multilevel inverter with voltage boosting and CMV reduction capabilities has been studied. In [31], a novel modulation method has been proposed to reduce the CMV and balance the NP voltage and apply to the line voltage coordinate system.…”