• Journal of Power Electronics
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• 제13권5호
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• pp.829-840
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• 2013

The modified sinusoidal pulse-width modulation (SPWM) is one of the PWM techniques used in three-phase AC-DC buck converters. The modified SPWM works without the current sensor (the converter is current sensorless), improves production of sinusoidal AC current, enables obtainment of near-unity power factor, and controls output voltage through modulation gain (ranging from 0 to 1). The main problem of the modified SPWM is the huge starting current and voltage (during transient) that results from a large step change from the reference voltage. When the load changes, the output voltage significantly drops (through switching losses and non-ideal converter elements). The single-input single-output (SISO) approach with minor-loop voltage feedback controller presented here overcomes this problem. This approach is created on a theoretical linear model and verified by discrete-model simulation on MATLAB/Simulink. The capability and effectiveness of the SISO approach in compensating start-up current/voltage and in achieving zero steady-state error were tested for transient cases with step-changed load and step-changed reference voltage for linear and non-linear loads. Tests were done to analyze the transient performance against various controller gains. An experiment prototype was also developed for verification.

• Journal of Power Electronics
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• 제15권4호
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• pp.939-950
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• 2015

A single-stage AC-AC converter has been designed for a wind energy conversion system (WECS) that eliminates multistage operation and DC-link filter elements, thus resolving size, weight, and reliability issues. A simple switching strategy is used to control the switches that changes the variable-frequency AC output of an electrical generator to a constant-frequency supply to feed into a distributed electrical load/grid. In addition, a modified random sinusoidal pulse width modulation (RSPWM) technique has been developed for the designed converter to make the overall system more efficient by increasing generating power capacity and reducing the effects of inter-harmonics and sub-harmonics generated in the WECS. The technique uses carrier and reference waves of variable switching frequency to calculate the firing angles of the switches of the converter so that the three-phase output voltage of the converter is very close to a sine wave with reduced THD. A comparison of the performance of the proposed RSPWM technique with the conventional SPWM demonstrated that the power generated by a turbine in the proposed approximately increased by 5% to 10% and THD reduces by 40% both in voltage and current with respect to conventional SPWM.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.256-259
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• 1999

A new PWM method for voltage source inverters is described. The switching instants determination of the proposed PWM scheme is simple. Therefore, hardware implementation with a microprocessor system is easy and high frequency operation of an inverter can be obtained. The maximum line-to-line output voltage of 3-phase inverter with the proposed scheme is larger than that of the SPWM inverter under a linear modulation region. Principle of the proposed PWM method is described and harmonic characteristic analysis is carried out.

• 전력전자학회논문지
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• 제7권3호
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• pp.262-271
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• 2002

견인전동기 구동시스템에 사용되는 PWM 인버터는 전력용량이 크기 때문에 스위칭주파수가 제한되며, 따라서 전자기적 가청소음이 발생한다. 이러한 가청소음을 줄이기 위하여 새로운 MRSF-PWM 방식을 제안한다. 제안한 MRSF-PWM 방식에서는 고조파를 확산시키기 위해 삼각파와 톱니파를 함께 운송파로 사용하며, 출력전압의 선형제어범위를 넓히기 위해 정현파에 3차 고조파를 주입한 파형을 기준파로 사용한다. MRSF-PWM 방식의 타당성을 검증하기 위하여 컴퓨터 시뮬레이션을 수행하였다. 그 결과, MRSF-PWM 방식이 선형성 및 고조파 확산면에서 다른 RPWM 방식보다 우수하며 가청소음 저감면에서 SPWM 방식보다 효과적임을 확인하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.252-255
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• 2004

This paper presents a new technique to generate the 1-bit signal by decoding Pulse Width Modulation (PWM) signal to a binary file before programming onto the ROM. Since each PWM signal requires only 1-bit digital signal, PWM signal and other forms of digital signal related to multi-bit can be simply generated. The results demonstrate that using this new technique to generate the PWM signal can simplify the process and hardware complication. Moreover, the signal's data and frequency can be easily modified by programming the data onto the ROM and using the counter, respectively, which can reduce the size of the circuit and make the PCB easier.