• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.8
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• pp.448-454
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• 1999

This paper describes a new dc-ac inverter system which for achieving sinusoidal ac waveform makes use of parallel loaded high frequency resonant inverter consisting of full bridge. Each one of the pair of switches in the inverter is driven to synchronous output frequency and the other is driven to PWM signal with resonant frequency proportional to magnitude of sine wave. A forced discontinuous conduction mode is used to realize the quasi-sinusoidal pulse in each switching period. Therefore the inverter generates sinusoidal modulated output voltage including carrier frequency that is resonant frequency. Carrier frequency components of modulated output voltage is filtered by low pass filter. Since current through switches is always zero at its turn-on in the proposed inverter, low stress and low switching loss is achieved. Operating characteristics of the proposed system is analyzed in per unit system using computer simulation. The output voltage of if includes low harmonics and it is almost close to sine wave. Also, the theoretical analysis is proved through the experimental test.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.4
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• pp.188-193
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• 2017

In this paper, a ZVS-PWM high-frequency inverter with a PWM control function is applied to commercial system 220[Vrms], and a resonator type ZVS-PWM high-frequency inverter circuit with a fixed-two methods were proposed. The parameters of the transformer model equivalent circuit of a copier fixing device, which is an essential element in the parameter optimization of the proposed circuit, are obtained by using a high-frequency amplifier and its frequency characteristics are described. The proposed method compared to the existing single-ended ZVS-PFM high frequency inverter can suppress the voltage and current peak value of the power semiconductor switching device and reduce the switching loss. The efficiency of the proposed method itself is 98[%] at rated power output. Also, the efficiency of 96[%] can be obtained even at low output, so that the proposed high frequency inverter is very efficient inverter. The total efficiency from the commercial AC input to the inverter output is 93[%] at rated, which is considered efficient for use in copying machines. In addition, the diode bridge loss accounts for the largest portion of the overall system efficiency distribution. On the other hand, the nonparallel filter has a very low loss.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1066-1071
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• 2005

This paper presents the two lossless auxiliary inductors-assisted voltage source type half bridge (single ended push pull: SEPP) series resonant high frequency inverter for induction heated fixing roller in copy and printing machines. The simple high-frequency inverter treated here can completely achieve stable zero current soft switching (ZCS) commutation for wide its output power regulation ranges and load variations under its constant high frequency pulse density modulation (PDM) scheme. Its transient and steady state operating principle is originally described and discussed for a constant high-frequency PDM control strategy under a stable ZCS operation commutation, together with its output effective power regulation characteristics-based on the high frequency PDM strategy. The experimental operating performances of this voltage source SEPP ZCS-PDM series resonant high frequency inverter using IGBTs are illustrated as compared with computer simulation results and experimental ones. Its power losses analysis and actual efficiency are evaluated and discussed on the basis of simulation and experimental results. The feasible effectiveness of this high frequency inverter appliance implemented here is proved from the practical point of view.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.11a
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• pp.415-420
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• 2005

This paper presents the two lossless auxiliary inductors-assisted voltage source type half bridge (single ended push pull: SEPP) series resonant high frequency inverter for induction heated king roller in copy and printing machines. The simple high-frequency inverter treated here can completely achieve stable zero current soft switching (ZCS) commutation for wide its output power regulation ranges and load variations under its constant high frequency pulse density modulation (PDM) scheme. Its transient and steady state operating principle is originally described and discussed for a constant high-frequency PDM control strategy under a stable ZCS operation commutation, together with its output effective power regulation characteristics-based on the high frequency PDM strategy. The experimental operating performances of this voltage source SEPP ZCS-PDM series resonant high frequency inverter using IGBTs are illustrated as compared with computer simulation results and experimental ones. Its power losses analysis and actual efficiency are evaluated and discussed on the basis of simulation and experimental results. The feasible effectiveness of this high frequency inverter appliance implemented here is proved from the practical point of view.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.171-174
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• 1991

Among the various PWM methods, the hysteresis-band current control PWM method is popularly used because of its simplicity of implementation, fast response characteristics and inherent peak current limiting capability. However, the current control PWM method with a fixed hysteresis-band has the disadvantage that switching frequency decreases and current ripple is high as the increasing of back-EMF. As a result, load current contains excess harmonics. This paper describes a adaptive hysteresis-bandwidth control algorithm so as to maintain the average switching frequency constant and decrease the current ripple where the hysteresis bandwidth is derived as a relation with the switching frequency. This control algorithm is applied to the surface-type brushless DC motor with separated winding and using the computer simulation, the validity of its algorithm is proved.

• Journal of information and communication convergence engineering
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• v.6 no.4
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• pp.417-420
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• 2008

Solar electric systems have very little impact on environment, making them one of the cleanest power-generating technologies available. While they are operating, PV systems produce no air pollution, hazardous waste, or noise, and they require no transportable fuels. In PV system design, the selection and proper installation of appropriately-sized components directly affect system reliability, lifetime, and initial cost. In this research, we have studied the PWM(Pulse Width Modulation) signals. I proposed an efficient photovoltaic power interface circuit incorporated with a DC-DC converter and a sine-pwm control method full-bridge inverter. In grid-connected solar power systems, the DC-DC converter operates at high switching frequency to make the output current a sine wave, whereas the full-bridge inverter operates at low switching frequency which is determined by the ac frequency. Thus, it can reduce the switching losses incurred by the full-bridge inverter. Full-bridge converter is controlled by using microprocessor control method, and its operation is verified through computer aided simulations.

• Proceedings of the IEEK Conference
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• 2002.06e
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• pp.63-66
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• 2002

This paper has been studied the parallel resonant inverter which controlling the constant power and tracking the load resonant frequency with PLL is possible, in order to minimize switching losses. The current-fed full-bridge type parallel resonant inverter of an induction heating system was composed of IGBT in switching device. For regulating the output power of an induction heating system, the Fuzzy controller is used. The Fuzzy controller makes the control signal for a stable power regulating control and when reference is changed, it is superior to adaptability. It has been evaluated a stable behavior for a noise with switching and a load disturbance.

• Journal of Power Electronics
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• v.12 no.3
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• pp.387-398
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• 2012

It is known that transformer based power supplies for ozone generators have low efficiency, high cost and exhibits a limited frequency range of operation. To overcome these disadvantages, this paper proposes a high frequency ozone generator with the absence of a transformer. The voltage step-up is achieved only by utilizing the resonant tank. This is made possible by a novel combination of ozone chamber materials that allow ozone to be generated at only 1.5 - 3.5 $kV_{p-p}$. The input to the resonant tank is driven by a PWM full bridge resonant inverter. Furthermore, zero-current zero-voltage switching (ZCZVS) operation is achieved by employing a duty factor of 25% between the switches of the full bridge. The advantages of the proposed system include high efficiency, low cost and the ability to control ozone production by varying the input voltage to the inverter. The prototype is verified by both simulation and experimental results.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.174-176
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• 2003

The power conversion system must be increased switching frequency in order to achieve a small size, a light weight and a low noise. This paper proposes a skillful and a concise PWM DC-DC converter employing both zero voltage and zero current high frequency switching(ZVCS) operation. The Proposal ZVCS circuit is composed with resonant circuit using active resonant condenser. And this circuit provides switches with ZVS and ZCS by quasi resonant only that switching transients appear. This operation results in reduction of stress and losses in the power devices and resonant components. Some simulation results are included to confirm the validity of the analytical results.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.296-299
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• 2003

The conventional DTC strategy provides a fast torque response even though it has very simple scheme consisted with only two hysteresis band comparators and a switching table for torque and flux control. Drawbacks of the conventional DTC are relatively high torque ripple at low speed and variation of the switching frequency according to motor speed. In this paper, the new direct torque control(DTC) schemes are proposed. Those schemes are based on the torque slope and enable to reduce the torque ripple and maintain the switching frequency constantly.