Traditional Pulse Width Modulation Control Research Articles

Acoustic Noise of Induction Motor With Low-Frequency Model Predictive Control

This paper studies the acoustic noise of induction motor with low switching frequency model predictive control and compares its noise performance with the traditional pulse width modulation with proportional-integral controllers. First, the relationship among the air-gap magnetic field, the electromagnetic force, and the acoustic noise is modeled to describe the influence of control algorithm on the noise characteristics of motors. As the counterpart with the traditional pulse width modulation control, a finite control set model predictive control strategy with low switching frequency is proposed. The steady-state performance and switching frequency constraint ability of the proposed model predictive control strategy are verified on the experimental platform. Second, the noise spectrums of these two control strategies are sampled and compared in different operating conditions, and the influence of the weighting factor on the noise spectrum is also discussed. It is proved by the experimental results that model predictive control has better noise performance than the traditional sinusoidal pulse width modulation under the same switching frequency and the total harmonic distortion of stator current.

Variable switching frequency modulation scheme for PWM converter integrating series‐resonant voltage multiplier‐based voltage equalizer for photovoltaic strings under partial shading

Conventional photovoltaic (PV) systems require not only a converter for string control but also preferably a voltage equalizer to preclude partial shading issues, which increases the system complexity because two separate converters are necessary. A single‐switch, single‐magnetic pulse width modulation (PWM) converter integrating a series‐resonant voltage multiplier (SRVM) as a voltage equalizer has been proposed in previous work to simplify PV systems by reducing the converter count. The equalization performance of the integrated converter employing a traditional PWM control scheme, however, is unavoidably impaired because the effective operation period of the SRVM in a switching cycle is relatively short at a fixed switching frequency fS. This paper proposes a variable‐fS PWM control technique to improve the voltage equalization performance of the SRVM. The proposed modulation scheme adjusts fS according to the duty cycle variation so that the SRVM's effective operation period is extended. Detailed mathematical analysis revealed that the proposed modulation scheme could improve the equalization performance of the integrated converter. The experimental equalization tests for three PV modules connected in series were performed emulating a partial shading condition. With the proposed modulation scheme, the extractable maximum power from the partially shaded string increased by up to 7%, demonstrating the improved equalization performance of the SRVM. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Application of pulse width modulation and by-pass valve control for increasing energy efficiency of pneumatic actuator system

Control of a pneumatic actuator using pulse width modulation (control) represents a good alternative for control of pneumatic actuator that uses proportional valve. Important advantage of pulse width modulation control is fewer consumption of compressed air. In addition, air consumption can be further reduced by the use of inter-chamber cross flow (chamber by-passing). This article discusses joint application of pulse width modulation and by-pass chamber control on the example of pneumatic rodless cylinder which is controlled by programmable logic controller. Saving of compressed air was experimentally determined, as well as the influence of inter-chamber cross flow on the quality of the control. With this application of pulse width modulation and by-pass valve control, pneumatic actuator system shows that 30% of energy can be saved under the same working conditions in comparison to the traditional pulse width modulation control system.