• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.1
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• pp.27-33
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• 2016

A pulse-width modulation (PWM) method for common mode noise reduction in a PWM inverter connected to a single-phase grid is proposed in this study. The extensively used conventional switching method may experience common mode voltage problems, which generate current leakage and electromagnetic induction problems. In the proposed switching method, the neutral point of the output voltage is always fixed at both ends of the input voltage to reduce common mode noise. The validity of the proposed method is proven through simulation and experimental results.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.3
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• pp.273-280
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• 1990

To prevent the shoot-through phenomena in a PWM inverter, a short dead time is usually provided between a pair of switching transistors in the same leg of the inverter. In this approach, the amount of the dead time is designed to meet the worst case condition of the inverter transistors and the base drive elements. So, in normal cases, relatively large portion of the dead time is unnecessary and it results in an undesirablecurrent waveform distortion and generates ripple torque on the motor shaft. In this paper, a new base drive method to remove the undesirable portion of the dead time is described. The method senses the transistor on/off states to interlock the other transistor of the leg without the external dead time. Also, for the transistors of large current rating, the Darlington drive circuit is combined to the proposed method and is tested to verify the effectiveness. The experimental results of the proposed method are described and compared with those of the conventional dead time method.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.218-219
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• 2016

This paper present Phase Shifted with carrier based on Sinusoidal PWM(SPWM) by using Cascaded NPC/H-birdge converter. The proposed Phase Shifted PWM method is adding third harmonic injection in switching signal. The advantage of the proposed method is reducing the voltage and capacity of the capacitor. This paper compare general Phase Shifted method with proposed Phase Shifted method that added the third harmonic injection. Each PWM method is tested without considering the switching loss by using PSIM 9.1.4 simulation.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1084-1087
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• 2002

This paper presents an improved fuzzy logic-based adaptive PWM technique. A fuzzy logic- based adaptive PWM technique determines the optimal output voltage vector which takes into account both direction of back-emf and direction of current error vector. This technique has a simple structure and a good level of stability, but it has disadvantages. The longer sampling period, the larger current error. Because there is no considerations of the current error magnitude of each phases. The proposed method improves the control performance by selecting the optimum switching pattern in which the magnitudes of current errors are considered introducing space vector concept. Simulation results using Matlab/Simulink show that the proposed control method reduces current error keeping the merit of previous one.

• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.319-322
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• 1990

Self-controlled permanent magnet synchronous motor (PMSM) has similar operating characteristics as seperately excited dc motor. It is favored in servo applications due to its improvement of efficiency and maintenance. This paper presents completely digitalized controller using microprocessor and voltage fed inverter. The speed control system for PMSM is implemented. To control the motor speed, the control system regulates the magnitude of Inverter output voltage by regular-sampled PWM method to generate sinusoidal PWM wave with microprocessor. And to keep the range of inverter switching frequency, it varies the number of pulse train according to the speed.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.451-455
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• 1991

The PWM control technique is proposed which can eliminate the harmonic components of the nonsinusoidal ac line current such as the current of 6-phase rectifier by injecting PWM current. TSC(Time-Sharing Control) is adopted to avoid the unbalance between three PWM injection currents at the three-phase system. Also a new power circuit for three-phase filter is suggested for realizing the proposed PWM control technique. The operation characteristics are investigated theoretically and experimentally to show the feasibility of the optimized injection method.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.415-419
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• 2004

The U filter has been generally used to filter the output voltage of PWM inverter to the sinusoidal waveform. The resonant voltage on the output voltage of PWM inverter may be generated due to LC filter. This paper proposed the algorithm to damp the resonant voltage using the virtual resistor without decreasing the efficiency by the power loss in the real resistor The method is appled to the vector controlled induction motor driven by the PWM inverter with the LC filter. The simulation results are carried out to verify the performances of the proposed algorithm.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.384-388
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• 2004

High frequency common mode voltage produced by power inverters are a major cause of conducted EMI, creating motor ground currents, bearing currents and other harmful by products. This paper focuses on a new SVPWM method with random PWM injection to reduce conducted EMI noise. A New PWM technique associated with the common mode voltage can be significantly reducing and contributes to mitigate. The common mode voltage to $50\%$ in comparison with that for conventional SVPWM technique. Validation of the theory and reduction methods are then performed experiment ally based on an induction motor drive.

• Journal of Power Electronics
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• v.12 no.4
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• pp.587-594
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• 2012

When a PWM rectifier has a low DC-link voltage during startup, the output voltage vector cannot be high enough to regulate the input current. This lack of a PWM rectifier output voltage vector can cause an unregulated inrush current when the rectifier operation starts. This paper presents a PWM rectifier start-up current control algorithm for when it starts operation with a lower DC-link voltage than unloaded condition case. To avoid the unregulated inrush current caused by a lack of DC-link voltage, the proposed control scheme regulates the one phase current with one switch chopping and it generates the current command considering the uncontrolled current magnitude information, which is calculated in advance. Simulation and experiment results support the validity of the proposed method.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.35 no.6
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• pp.217-225
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• 1986

This paper describes the Optimal PWM strategy to reduce a pulsating harmonic torque for a variable-speed drive of 3 phase induction motor. This paper suggests the new Optimal control theory which consists of 1) defining a performance index related to the unwanted effects of the voltage harmonics, (i.e., the components of pulsating harmonic torques) 2) achieving its minimization by a suitable choice of the switching patterns. (i.e., of the commutation angles) This PWM strategy is compared with the conventional SPWM strategy by numerical method. It is believed that this proposed strategy can reduce more harmonic components and pulsating harmonic torques than SPWM strategy. Also, We could verify the validety of the numerical method by a result of simulation analysis of a variable speed 3phase induction motor.