• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.635-639
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• 2004

This paper presents a simple PWM method to control three phase four leg multilevel inverters, which have been developed for supplying electrical power to three phase unbalanced load and for related power active filters. The method is derived from a general correlation between space vector PWM (SVPWM) method and carrier based PWM (CPWM) method. As an advantage, the simplicity and flexibility of the proposed CPWM control can be obtained and the complicated calculations of the 3-D SVPWM concepts can be avoided. The method has been mathematical formulated and demonstrated by simulation results.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.225-227
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• 2008

This paper deals with the implementation on a Field Programmable Gate Array (FPGA) of PWM switching patterns for a voltage multilevel inverter. The reference data in main microcontroller is transmitted to the FPGA through 16 general purpose I/O ports. Herein, three-phase reference voltage signals are addressed by the last 2-bit (bit 15-14) and their data are assigned in remaining 14-bit, respectively. The carrier signals are created by 16-bit counter in up-down counting mode inside FPGA according to desirable topology. Each reference signal is compared with all carrier signals to generate corresponding PWM switching patterns for control of the multilevel inverter. Useful advantages of this scheme are easy implementation, simple software control and flexibility in adaptation to produce many PWM signals. Some simulations and experiments are carried out to validate the proposed method.

• Journal of Power Electronics
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• v.18 no.2
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• pp.604-614
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• 2018

This paper proposes a synchronous switching technique for a Vienna rectifier that uses carrier-based pulse width modulation (CB-PWM). A three-phase Vienna rectifier, similar to a three-level T-type converter with three back-to-back switches, is used as a PWM rectifier. Conventional CB-PWM requires six independent gate signals to operate back-to-back switches. When internal switches are operated synchronously, only three independent gate signals are required, which simplifies the construction of gate driver circuits. However, with this method, total harmonic distortion of the input current is higher than that with conventional CB-PWM switching. A reactive current injection technique is proposed to improve current distortion. The performance of the proposed synchronous switching method and the effectiveness of the reactive current injection technique are verified using simulations and experiments performed with a set of Vienna rectifiers rated at 5 kW.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.11
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• pp.896-904
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• 1989

PWM techniques which eliminate and reduce harmonics of output voltage in PWM Inverter driving System with fluctuating input volotage are described. First, harmonic factors are analyzed from harmonic equation of general PWM waveform and by examination of control possiblity of each factor, controllable factor is selected. Applying controllable factor to NPWM, PWM techniques using reference wave and carrier wave modulation are introduced. Actually, by the experiment applied with this strategy, the reduction of harmonics of output voltage is confirmed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.95-99
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• 1996

In this paper, we proposed a method to measure the gap between the magnetic pole and the levitated object applying the inductance characteristic which vary according to gap. We made a driving circuit which supply the control input PWM(Pulse Width Modulation) signal and the carrier PWM signal to estimate the gap. Because the inductance is a function of gap, and the current of the carrier signal is a function of the inductance. We investigated the validity of the proposed method through the experimental results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.5
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• pp.922-930
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• 2009

An optimized PWM switching strategy for an induction motor voltage control is developed and demonstrated. Space vector modulation in voltage source inverter offers improved DC-bus utilization and reduced commutation losses and has been therefor recognized the preferred PWM method especially in case of digital implementation. An optimized PWM switching strategy for an induction motor voltage control consists of switching between the two active and one zero voltage vector by using the proposed optimal PWM algorithm. The preferred switching sequence is defined as a function of the modulation index and period of a carrier wave. The sequence is selected by using the inverter switching losses and the current ripple as the criteria. For low and medium power application, the experimental results indicate that good dynamic response and reduced harmonic distortion can be achieved by increasing switching frequency.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.216-222
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• 2003

Today we have excellent motor drive system using high frequency carrier PWM control voltage source inverter in the other hand, we have met serious problems caused by high frequency switching. PWM Cyclo-converter called Matrix converter is expected as the new strategy Possible to improve these problems and add some more convenient features suitable for new drive system. in this Paper, we will introduce the background, features and outline of this converter, and additionally introduce some remarkable activity on this converter

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.325-329
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• 2000

An effective Carrier-Based PWM scheme that enables the instantaneous quality of each branch point voltage of a diode clamped 4-level inverter to be reduced at a low modulation index is described. This scheme presents a computed zero sequence voltage of PWM by the feedback of both DC-link voltages and load currents. The proposed PWM scheme enables to increase the controllable region of DC-link voltage and makes it possible to operate with small DC-link capacitors. The validity of the proposed PWM scheme is verified by simulation results.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.738-750
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• 2017

In this paper, carrier-based pulse width modulation (CBPWM), space vector PWM (SVPWM) and reduced switching losses PWM (RSLPWM) for the three-level neutral point clamped (NPC) inverter are introduced. In the case of the neutral point (NP) potential (NPP) offset, an asymmetric disposition PWM (ASPDPWM) strategy is proposed, which can output PWM sequences correctly and suppress the lower order harmonics of the inverter effectively. An NPP balance strategy based on carrier based PWM (CBPWM) is analyzed. A hybrid modulation strategy combining RSLPWM and the NPP balance based on CBPWM is proposed, and hysteresis control is adopted to switch between the two modulation strategies. An experimental prototype of the three-level NPC inverter is built. The effectiveness of the hybrid modulation is verified with a resistance-inductance load and a permanent magnetic synchronous motor (PMSM) load, respectively. The experimental results show that reduced switching losses and an acceptable NPP can be effectively achieved in the hybrid modulation strategy.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.327-331
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• 2003

This paper proposes a novel ZVZCS-PWM Boost Converter. It enables the main switch to be turned on and off with both zero voltage and zero current and the auxiliary switch to be turned on and off with ZCS, the rectify diode to be turned on and off with ZVS. Moreover, this converter is suitable for not on]y minority carrier device but also majority carrier device. The auxiliary resonant circuit of the proposed boost converter is placed out the main power path, therefore, there are no voltage/current stresses on the main switch and diode. The operation of the proposed boost converter is explained and analyzed theoretical and experimentally, from a prototype operating at 100kHz, with an input voltage rated at 50V.