• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.11
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• pp.575-582
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• 2001

This paper presents a calculating method of switching angle for adaptive switched reluctance motor (SRM) drive of a drill. The operation of the SRM is completely characterized by the flux linked by one phase winding which depends only on the current in that same phase winding and the rotor position. An efficiently adaptive SRM drive is possible on appropriately scheduling the commutation angles with accurate rotor position, supplied current value and speed information. An adaptive SRM drive with reduction torque ripple should be controlled by an optimized phase current control along with rotor position. Therefore, we are suggested a computing method of switching turn-on and off angles for adaptationally SRM operation with varied rotor speed and load. To probe the computing method, we have some simulation and experiment, it is shown a good result that can be computing the optimized switching angles for an electric drill motor.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.2
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• pp.166-174
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• 2017

This study proposes a compensation method for the dead-time effects on a single-phase grid-connected inverter. Dead time should be considered in the pulse-width modulation gating signals to prevent the simultaneous conduction of switching devices, considering that a switching device has a finite switching time. Consequently, the output current of the grid-connected inverter contains odd-numbered harmonics because of the dead time and the nonlinear characteristics of the switching devices. The effects of dead time on output voltage and current are analyzed in this study. A new compensation algorithm based on second-order generalized integrator is also proposed to reduce the dead-time effect. Simulation and experimental results validate the effectiveness of the proposed compensation algorithm.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.1
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• pp.91-97
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• 2014

Recently, the LED(Light Emitting Diode) is expected to replace conventional lamps including incandescent, halogen and fluorescent lamps for some general illumination application, due to some obvious features such as high luminous efficiency, safety, long life, environment-friendly characteristics and so on. To drive the LED, a single stage PFC(Power Factor Correction) flyback converter has been adopted to satisfy the isolation, PFC and low cost. The conventional flyback LED driver has the serious disadvantage of high 120Hz output current ripple caused by the PFC operation. To overcome this drawback, a new PFC flyback with low 120Hz output current ripple is proposed in this paper. It is composed of 2 power stages, the DCM(Discontinuous Conduction Mode) flyback converter for PFC and BCM(Boundary Conduction Mode) boost converter for tightly regulated LED current. Since the link capacitor is located in the secondary side, its voltage stress is small. Moreover, since the driver is composed of 2 power stages, small output filter and link capacitor can be used. Especially, since the flyback is operated at DCM, the PFC can be automatically obtained and thus, an additional PFC IC is not necessary. Therefore, only one control IC for BCM boost converter is required. To confirm the validity of the proposed converter, theoretical analysis and experimental results from a prototype of 24W LED driver are presented.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.91-94
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• 2006

Miniature BLDC is widely used in industrial applications and especially medical appliances because of there character that high driving efficiency and high torque characteristic. However torque ripple of a high speed miniature BLDC is serous in switching period cue to the very electrical time constant. This paper present instant voltage and current control for torque ripple reduction of a high speed miniature BLDC. Computer simulation and experiment test for 40,000 rpm miniature BLDC show the verification of the proposed control method.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.48-50
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• 2001

This paper presents the switching angle and the 1/2-phase hybrid exciting method to minimize torque ripple in the 6/4 Switched Reluctance Motor (SRM). The inductance in SRM is dependent on rotor position and current. Therefore, the inductance profile is expressed as an approximate function based on FEM data. And then, the dynamic characteristics are simulated by Matlab simulink using the derived inductance function. The torque ripple resulting from single phase exciting and 1/2-phase hybrid exciting is compared.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.2
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• pp.158-163
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• 2001

Current Source Inverter(CSI), operated in square wave mode, is more efficient thant the PWM CSI because of increased cost, greater complexity of control algorithm and substantial switching losses, EMI. But, the square wave output current of CSI, rich in low order harmonics produce motor torque ripples. Therefore, in this paper, describes active power filters for compensating square wave input current of current source induction motor. Also, notch filtering as compensation algorithm is employed. To confirm the validity of proposed system, PSIM simulation results are presented and discussed.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.1
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• pp.54-59
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• 1996

As the current shape of SRM is of pulse type and changed by the motor parameters and drive conditions, the influences on the drive efficiency by control method are more than other types of motors. In this paper, a proper excitation condition to drive a SRM with high efficiency is proposed and tested. It is derived from the conditions that the phase current of a SRM is to be flat-topped at various drive. The saturation effect of magnetic circuit is accounted for more accurate analysis. Experimental tests are executed to verify the proposed excitation method. This drive system is easy to commutate and also advantageous in reducing torque ripple. (author). 6 refs., 10 figs., 1 tab.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.189-190
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• 2015

This paper investigates an economic and highly efficient power converter topology and its modulation scheme for 60kW rapid EV charger system. The target system consists of three-phase three-switch buck-type rectifier topology. A new Carrier Based PWM scheme along with its simple implementation using logic gates is introduced in this paper. This PWM scheme replaces the diode rectifier equivalent switching state with an active switching state producing the effectively same current flowing path. As a result, the distortion of input current during the polarity reversal of capacitor line voltage can be mitigated. The proposed modulation technique is confirmed through simulation verification. The proposed modulation technique and its implementation scheme can expand the operation range of the three-phase three-switch buck-type rectifier having ac input and capacitor ripple current of high quality.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1391-1401
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• 2017

In this paper, a secondary resonance half-bridge dc-dc converter with an inductive output filter is presented. The primary side of such a converter utilizes asymmetric pulse width modulation (APWM) to achieve zero-voltage switching (ZVS) of the switches, and clamps the voltage of the switch to the input voltage. In addition, zero current switching (ZCS) of the output diode is achieved by a half-wave rectifier circuit with a filter inductor and a resonant branch in the secondary side of the proposed converter. Thus, the switching losses and diode reverse-recovery losses are eliminated, and the performance of the converter can be improved. Furthermore, an inductive output filter exists in the converter reduce the output current ripple. The operational principle, performance analysis and design equation of this converter are given in this paper. The analysis results show that the output diode voltage stress is independent of the duty cycle, and that the voltage gain is almost linear, similar to that of the isolation Buck-type converter. Finally, a 200V~380V input, 24V/2A output experimental prototype is built to verify the theoretical analysis.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.4
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• pp.143-148
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• 2023

Among the characteristics of SRM, due to nonlinearity, it is difficult to properly operate to form maximum torque and minimum torque pulsation. In addition, in the case of fixed switching angle control, torque formation according to speed variation is unstable, thereby reducing efficiency. Therefore, active switching angle control according to speed variation is required. Therefore, active switching angle control according to speed variation is required. In this paper, a method for improving driving performance by reducing torque ripple by automatic control of the advance angle and increasing output torque was sought from the problem caused by the nonlinearity of the SRM. In addition, the optimal operation of SRM due to the switching variable according to the performance of the hysteretic current controller was examined.