For Four-switch Three-phase Inverter Research Articles

An improved double‐vector model predictive control strategy for four‐switch three‐phase inverter‐fed permanent magnet synchronous motor based on visualisation analysis considering DC voltage pulsation

AbstractTo address the problem of considerable current distortions in traditional single‐vector model predictive control (MPC) method for four‐switch three‐phase inverter (FSTPI)‐fed permanent magnet synchronous motor, a double‐vector MPC scheme has been studied. However, it still lacks a sufficient theoretical foundation, causing doubts about its effectiveness. To perfect this deficiency, a novel visualisation analysis scheme considering DC voltage pulsation is presented to demonstrate the validity of the traditional double‐vector MPC method for FSTPI. The analysis results reveal for the first time that the traditional double‐vector MPC method is not always superior to the single‐vector method as there is no zero voltage vector for FSTPI. So, a new virtual voltage vector is defined to compensate the deteriorated control performance caused by the absence of zero voltage vectors, based on which an improved double‐vector MPC method is further put forward to reduce the current ripples. Then, the presented visualisation analysis is adopted to demonstrate the validity of the improved MPC strategy under pulsating DC voltage conditions. Finally, a new voltage sector division technology is further put forward to simplify the implementation steps of the presented method. Contrastive experimental studies demonstrate the availability of the improved MPC strategy.

Simplified MPCC for four‐switch three‐phase inverter‐fed PMSM

A simplified model predictive current control (MPCC) for four-switch three-phase inverter (FSTPI)-fed permanent magnet synchronous motor (PMSM) considering the periodic fluctuation of the capacitor voltages is proposed. After analysing the inherent features of the FSTPI-fed PMSM system, an offset voltage vector and an ideal reference voltage vector are defined, which allows to deal with the reference voltage in the ideal voltage vector plane. Thus, the sector division is simplified. Furthermore, a concept of virtual duty cycle is introduced to employ an equivalent null vector in the MPCC in order to reduce the current ripples. Combining with a simple sector division, the active voltage vector and its virtual duty cycle are determined with only one prediction. Comparative experimental studies between the conventional and the proposed MPCC are executed to validate the feasibility of the proposed simplified MPCC.

Sector determination for SVPWM based four‐switch three‐phase VSI

Sector determination for a normalised space vector pulse width modulation (SVPWM) scheme is proposed for four-switch three-phase (FSTP) voltage source inverter (VSI) by using already available stationary reference frame stator voltages without requiring complex trigonometric calculations. The proposed method has been simulated by using MATLAB/Simulink and implemented using a VSI with a TMS320F28335 floating-point digital signal processing. Simulation and experimental results show the feasibility and effectiveness of the proposed SVPWM algorithm for FSTP inverter.

Instantaneous Vector Control of Four Switch Three Phase Inverter Fed Induction Motor Drive

This paper proposes a transformation matrix to generate Pulse Width Modulation (PWM) signals for Four Switch Three Phase Inverter (FSTPI) using vector control. The feasibility of the control strategy is verified by proving the power invariance before and after the transformation. Simulation and experimental results have verified the validity and effectiveness of the proposed method to obtain instantaneous response in different operating conditions and provide fast speed response.

Unified PWM algorithm based on effective time for four‐switch three‐phase inverter

A unified pulse-width modulation (PWM) algorithm is proposed for four-switch three-phase inverter (FSTPI) to reveal the essential relationship among different PWM algorithms. The FSTPI generates only four active vectors and the zero vector is absent, so the zero vector can be synthesised by two opposite active vectors or all four vectors. Effective time for different phase is derived for the proposed unified PWM. By altering the distribution of effective time in a PWM period, various PWM algorithms with different equivalent zero vectors are implemented. In the proposed algorithm, sector identification and trigonometric function calculation are not required and the voltage fluctuation across the two dc-link capacitors is also taken into account. Thus, the desired output voltage can be synthesised simply and precisely. Experimental results confirm the effectiveness of the proposed unified PWM algorithm.

Adaptive PWM for four‐switch three‐phase inverter

An adaptive pulse width modulation (PWM) strategy is proposed for four-switch three-phase inverter (FSTPI) to improve the performance and simplify the algorithm. The FSTPI has a split DC-link and one phase of the AC load is connected to the neutral point. The conventional space vector PWM has a limited performance in the low-frequency region since the phase currents are unbalanced due to the neutral-point voltage fluctuation caused by the phase current flowing through the capacitors. To solve this problem, an adaptive PWM considering the neutral-point voltage fluctuation is proposed. Moreover, sector identification is unnecessary thus the algorithm is simplified. Experimental results demonstrate the validity and feasibility of the proposed strategy.

Vector control of FSTP inverter fed synchronous reluctance reluctance motor based maximum torque control

This paper presents a cost-effective vector control strategy for four switch three phase (FSTP) inverter fed a