Nonlinear Characteristics Compensation of Inverter for Low-Voltage Delta-Connected Induction Motor

Abstract

This paper proposes a scheme that can compensate for the nonlinear characteristics of voltage source inverters (VSIs) for low-voltage delta-connected induction motors (IMs). Due to the nonlinearity introduced by the dead-time, the on/off delay, and the voltage drop across the power device, the output voltage of VSIs is seriously distorted, causing distortion in the phase current of the IM, which will lead to output torque ripple. However, the existing compensation methods for three-phase VSIs are derived from star-connected loads, or ignore the conducting properties of power devices. Moreover, the current polarity detection near the current zero is quite complex. In this paper, by taking such nonlinear characteristics into consideration, especially the conducting property of metal-oxide-semiconductor field effect transistors (MOSFETs), an output voltage model of VSIs for low-voltage delta-connected induction motors is presented. After that, in view of the difficulty in detecting the line current polarity near the current zero which might lead to the wrong compensation, an advancing current crossing zero (ACCZ) compensation is proposed. Subsequently, a compensation scheme which combines the compensation based on the VSI output voltage model and ACCZ compensation is proposed. Finally, the proposed compensation scheme is implemented based on a digital signal processor (DSP) drive system. The experimental results show that the proposed scheme has better performance than the common method in terms of suppressing the effect of the nonlinear characteristics of VSI, which demonstrates that the proposed compensation scheme is feasible and effective for the compensation of the nonlinear characteristics of VSI for low-voltage delta-connected IMs.

A Vector Controlled Drive System for Electrically Power Assisted Steering Using Hall-Effect Sensors

“…29, there exist some differences between simulation and experimental results. These differences are due to the inverter nonlinearities caused by the deadtime [26], simulated load nonuniformity, and the noise and delay present in the measured stator currents.…”

Direct Torque Control for Series-Winding PMSM with Zero-Sequence Current Suppression Capability

“…In addition to the deadtime effects, the nonlinearity introduced by the on/off delay and the voltage drop across the power device [16,24] also causes zero-sequence disturbance voltage. The zero-sequence disturbance voltage is also associated with other factors, such as the zero-sequence back EMF and cross-coupling voltages in zero sequence [10].…”

“…The SWT is a special open-winding structure, which multiplexes the adjacent inverter legs located in the middle of the OWT [11]. The SWT retains the advantages of high bus voltage utilization and zero-sequence controllability while greatly reducing the number of power devices so that the cost and volume can be greatly decreased, which is the main concern in industrial applications [13,16,17].…”