• Journal of Power Electronics
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• v.5 no.2
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• pp.142-150
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• 2005

This paper presents a systematic approach to study the carrier based pulse width modulation (PWM) techniques applied to diode-clamped and cascade multilevel inverters by using multi-modulating patterns. This method is based on the description of controllable redundant parameters in the modulating signals. A unified mathematical formulation is presented for carrier based PWM methods, which obtains outputs similar to the corresponding space vector PWM. A full and separate control of the fundamental voltage, vector redundancies and phase redundancies can be obtained in the carrier based PWM. In this paper, the proposed PWM method and corresponding algorithm for generating multi-modulating signals will be formulated and demonstrated by our simulations.

• Journal of Advanced Marine Engineering and Technology
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• v.15 no.4
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• pp.54-69
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• 1991

This study deals with the position control of a hydraulic cylinder system operated by two port 3-way high speed solenoid valve in Pulse-Width-Modulation mode, instead of using conventional electro-hydraulic servovalve. Due to the complexity and the relatively poor reliability of the servovalve, an actuator using simpler and more study high speed solenoid valve will be presented. The high speed solenoid valve acts as converters of electronic pulse signal to hydraulic ones. It has been pointed out that there are practical problems to be solved in the PWM system, that is (1) accuracy of positioning control becomes considerably insufficient because the system is affected by on/off action of the solenoid valves, and (2) serious nonlinerality appears in the valve characteristics as a result of the switching behavior of the valves. As a method to overcome these defects, the differential PWM driving method of a hydraulic cylinder that improved the steady-state-error, flow rate nonlinearity in simple PWM, and the hydraulic hunting of dead time compensated-PWM driving is proposed in this study.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.1937-1939
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• 1998

This paper presents a simple switching method to generate a PWM pattern mostly relevant to signle-phase three-level PWM rectifier. The adopted PWM switching pattern is performed in a manner similar to the space vector PWM method, which is popularly used in the three-phase rectifier and inverter. A set of possible voltages has been selected so that an equation with a time integral considered within a sampling period should be satisfied every sampling time. The simulation result shows that the proposed control scheme is good in some performance criteria such as unity power factor, low harmonic distortion of input current, dynamic response and voltage balancing of two series-connected DC capacitors.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.2
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• pp.89-96
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• 1999

This paper proposes a common-mode voltage reduction method base on SVPWM(Space-Vector Pulsewidth Modulation) in three phase PWM converter/inverter system. By shifting the active voltage vector of inverter and aligning this to the active vector of converter, it is possible to eliminate a common-mode voltage pulse in one control period. Since the proposed PWM method maintains the active voltage vector, it does not affect the control performance of PWM converter/inverter system. Without any extra hardware, overall common mode voltage dv/dt and conrresponding leakage current can be reduced to two-third of the conventional three phase symmetric SVPWM scheme.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.457-462
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• 1987

This paper deals with the PWM controlled active AC power filter. A new PWM control method from the viewpoint of speed and simplicity is proposed. And a microprocessor-based controller is used to realize the active AC power filter. The existing PWM control methods are primarily based on Fourier series expansion and these methods need FFT calculation and solving nonlinear harmonic equations, which are heavy burden to real-time control. The proposed method is based upon generalized pulse series expansion and needs only definite integrals of harmonic signal. So, computational effort can be reduced by a large margin. The digital circuit using 16-bit microprocessor is designed to implement the actual active power filler.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.1
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• pp.283-288
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• 2000

This paper proposes a novel Pulse Width Modulation (PWM) method for microprocessor implementation of full-bridge PWM inverters. In the method, the period of unipolar full-bridge inverters is divided equally into the frequency modulation ratio and the reference fundamental amplitude and the inverter output fundamental amplitude are compared. Using this method, the turn-on time computation of each interval is very favored for the microprocessor implementation. The harmonic analysis shows that the harmonics can be ignored when the modulation ratio is enough large. The simulation and experimental results show the effectiveness of the proposed algorithms.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.7 no.3
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• pp.27-33
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• 1993

This paper presents the &tal controller for driving high frequency voltage fed PWM inverter that carrier frequency is over 2OkHz.We analyzed the conventional PWM to select a proper PWM pattern. as the result, obtained PWM pattern of the controller in which asynchronus staircase sinusoidal waveform is used as reference signal, and variable carrier ratio method was used for PWM control. The PWM controller is designed by fully digital method. Especially, Thk proposed controller is consisted of 8 bit one-chip microprocessor and digital logic. the former is for arithmetic and data processing, and the latter is for PWM pattern synthesis. Therefore, The responsibility and controllability is improved. Also, Data processing capability is improved using proper program to output modulation index with 9 bits. Circuits configuration of digital controller are made up of one chip 8051 and EPLD, and its controllability is tested by operating voltage fed inverter. Harmonics and current waveform is evaluated and analyzed for the voltage fed inverter system.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.5
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• pp.352-359
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• 2008

This paper proposes a current compensation method of a three phase PWM converter. The phase angle of utility voltage is essential to control a PWM converter. In the case of using synchronous reference frame PLL to detect the phase angle of the distorted source, harmonics of source voltage cause the phase angle to be distorted. PWM converter control by the distorted phase angle results in input current harmonics. This paper proposes a current compensation method which can limit THD of Input currents below to 5% that is the harmonic current requirements by IEEE std. 519. Its validity is verified by simulation and experiment.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.675-679
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• 1999

A single-phase PWM current source rectifier with a neutral leg is presented and throughly analyzed in this paper. This novel topology is implemented by adding an extra leg a step-down single phase PWM space vector modulation method to reduce the dc output voltage harmonics is proposed. The PWM pattern generation need a digital system. As compared with a conventional single-phase PWM rectifier, over 20% improvement of the total harmonics distortion in the output voltage can be obtained. Different SVM techniques are analyzed for this PWM rectifier and simulation result are presented.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.372-376
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• 2001

Due to several advantages of Pulse Width Modulation(PWM) Converter, such as unity power factor operation, elimination of low-order harmonics and regeneration of motor braking energy to source, the application range of PWM Converter has been rapidly extended in industrial application. Nowadays, vector control algorithm and space vector PWM(SVPWM) method are applied to improve the performances of PWM Converter, but vector control algorithm and SVPWM require to use Microprocessor and other digital devices in hardware, causing costly and somewhat large dimension system. In every practical application of energy conversion equipments, the design and implementation should be carried out considering cost and performance. High performance and low cost is the best choice for energy conversion equipments. So, this paper presents the practical design method and implementation results of 3-phase PWM Converter with analog hysteresis current controller, and verifies the performances of unit power factor operation and energy regeneration operation via experimental results.