• Journal of Institute of Control, Robotics and Systems
• /
• v.14 no.6
• /
• pp.535-542
• /
• 2008

This paper presents a high efficiency half-bridge DC-DC converter for an LED backlight drive system of LCD module inspection equipment. The proposed converter improves the converter efficiency using characteristics of the asymmetrical half-bridge converter and the self-driven synchronous rectifier, and thus improves the total efficiency of the LED backlight drive system. The synchronous rectifier applied to the proposed converter is the new topological synchronous rectifier, which changes slightly the transformer structure and the synchronous switch connection in the asymmetrical half-bridge converter with a conventional self-driven synchronous rectifier. Since the proposed converter utilizes the transformer leakage inductor as its resonant inductor, its structure is simplified. The proposed converter well operates under the universal DC input voltage ($250{\sim}380V$). The operational principle and a design example for a 100W prototype are discussed in detail, respectively. Experimental results are shown for the designed prototype converter under universal DC input voltage.

• Journal of Power Electronics
• /
• v.15 no.2
• /
• pp.544-554
• /
• 2015

This paper presents a steady-state operation analysis of full-bridge series-resonant inverters focusing on the distorted load current due to low-quality-factor resonant circuits in induction heating and other applications. The regions of operation based on the zero-voltage switching (ZVS) and non-zero-voltage switching (NON-ZVS) operations of the asymmetrical voltage-cancellation control technique are identified. The effects of a distorted load current under a wide range of output powers are also analyzed for achieving a precise ZVS operating region. An experimental study is performed with a 1kW prototype. Simulation and experimental studies have confirmed the validity of the proposed method. An efficiency comparison between the variable frequency method and the conventional fixed-frequency method is provided.

• Proceedings of the KIEE Conference
• /
• 1998.07f
• /
• pp.1899-1901
• /
• 1998

A five-level VSI(Voltage Source Inverter) is introduced as a SVC(Static Var Compensator) like a large scale power source. The problems in using SVC are that the power device can easily be destroyed by voltage unbalance and accurate reactive power control is difficult because of voltage variation. A asymmetrical PAM(Pulse Amplitude Modulation) switching pattern is proposed to solve this problem and analyze both fundamental component and harmonic current in the system. Through experimental results of 3.5 kVA experimental test system. It is confirmed that DC capacitor voltage can be controlled by asymmetrical PAM switching pattern control.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.3 no.1
• /
• pp.223-228
• /
• 1999

A five-level VSI(Voltage Source Inverter) is introduced as a SVC(Static Vu Compensator) like a large scale power source. The problems in using SVC are that the power device can easily be destroyed by voltage unbalance and accurate reactive power control is difficult because of voltage variation. A asymmetrical PAM(Pulse Amplitude Modulation) switching pattern is proposed to solve this problem and analyze both fundamental component and harmonic current in the system. Through experimental results of 3.5 kVA experimental test system, It is confirmed that DC capacitor voltage can be controlled by asymmetrical PAM switching pattern control.

• Proceedings of the KIPE Conference
• /
• 2000.07a
• /
• pp.237-240
• /
• 2000

A new control method using average comparison strategy have been proposed in this paper. This control method realizes sinusoidal input and output current. unity input displacement factor regardless of load power factor. Moreover compensation of the asymmetrical and harmonic containing input voltage is sautomatically realized and calculation time of control function is reduced.

• Journal of Power Electronics
• /
• v.16 no.4
• /
• pp.1504-1512
• /
• 2016

This paper presents a new single-phase asymmetrical cascaded multilevel DC-link inverter. The proposed inverter comprises two stages. The main stage of the inverter consists of multiple similar cells, each of which is a half-bridge inverter consisting of two switches and a single DC source. All cells are connected in a cascaded manner with a fixed neutral point. The DC source values are not made equal to increase the performance of the inverter. The second circuit is a folded cascaded H-bridge circuit operating at a line frequency. One of the main advantages of this proposed topology is that it is a modular type and can thus be extended to high stages without changing the configuration of the main stage circuit. Two control schemes, namely, low switching with selective harmonic elimination and sinusoidal pulse width modulation, are employed to validate the proposed topology. The detailed approach of each control scheme and switching pulses are discussed in detail. A 150W prototype of the proposed system is implemented in the laboratory to verify the validity of the proposed topology.

• Proceedings of the KIPE Conference
• /
• 2012.11a
• /
• pp.173-174
• /
• 2012

본 논문에서는 전기자동차용 부하 직렬 공진형 컨버터(Series-loaded Resonant Converter, SRC)타입의 탑재형 충전기 (On-Board Charger, OBC)의 추가 회로 없이 경부하 효율을 향상시키기 위한 스위칭 방법들을 비교 분석한다. 시스템에 적용할 스위칭 제어 방법은 Asymmetrical Duty Cycle Control (ADC)과 Asymmetrical Voltage-Cancellation Control (AVC) 방법이다. 각 제어 방법을 기존의 3.3kW SRC-OBC의 적용하여 경부하 영역에서의 효율을 확인하고 각 제어 방법의 타당성을 검증한다.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.40 no.12
• /
• pp.1230-1241
• /
• 1991

Asymmetrical pulse width modulated(APWM) control technique for AC chopper is proposed which can improve the input power factor. The ideal switching function for the proposed technique is derived and its optimal slope to maintain the input power factor to unity is calculated. By digital simulation several characteristics are investigated theoretically and then compared with those of the conventional PWM and the phase angle control technique. In order to maintain the input power factor to unity the optimal slope and the average value of the ideal switching function are calculated. The experimental results show a good agreement with the calculated ones, which proves the feasibility of the proposed technique.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.26 no.4
• /
• pp.256-262
• /
• 2021

Six-phase motors can be used in industrial applications, such as an electric vehicle, due to their high reliability and low current magnitude per phase. An asymmetrical PMSM with two sets of three-phase windings is a commonly used structure for six-phase motors, with each winding set demonstrating a phase difference of 30°. Although the asymmetrical PMSM presents low torque ripples, its dynamic torque response deteriorates due to coupled components in the two three-phase windings. The decoupled VSD control is applied to eliminate the coupling effect. Load ratio control of two inverters for the six-phase PMSM is proposed in this study. DQ currents are controlled on the basis of two synchronous reference frames, and the six-phase drive system can be changed to a three-phase drive system when one inverter presents fault conditions. The operation and effectiveness of the proposed algorithm is verified through simulation and experiments. The six-phase drive system is transferred to a three-phase drive system by changing the current reference of the second DQ reference frame. Moreover, control of both torque and speed exhibits satisfactory performance before and after the mode change.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.1
• /
• pp.271-279
• /
• 2015

Induction cooking application with multiple loads need high power inverters and appropriate control techniques. This paper proposes an inverter configuration with buck-boost converter for multiple load induction cooking application with independent control of each load. It uses one half-bridge for each load. For a given dc supply of $V_{DC}$, one more $V_{DC}$ is derived using buck-boost converter giving $2V_{DC}$ as the input to each half-bridge inverter. Series resonant loads are connected between the centre point of $2V_{DC}$ and each half-bridge. The output voltage across each load is like that of a full-bridge inverter. In the proposed configuration, half of the output power is supplied to each load directly from the source and remaining half of the output power is supplied to each load through buck-boost converter. With buck-boost converter, each half-bridge inverter output power is increased to a full-bridge inverter output power level. Each half-bridge is operated with constant and same switching frequency with asymmetrical duty cycle (ADC) control technique. By ADC, output power of each load is independently controlled. This configuration also offers reduced component count. The proposed inverter configuration is simulated and experimentally verified with two loads. Simulation and experimental results are in good agreement. This configuration can be extended to multiple loads.