• Proceedings of the KIEE Conference
• /
• 1994.11a
• /
• pp.138-140
• /
• 1994

In this paper, a three-phase active power filter using voltage- source PWM converter is designed to eliminate the harmonics and compensate the reactive power in the ac side. The predictive current control method is adopted, which provides constant switching frequency and low current ripple but has inherently one sampling error between the command and the actual current. Here we propose the algorithm which corrects this delay time. The converter voltage obtained from this current control can be accomplished by the space vector modulation method at a voltage-type converter. All control sequences of active filter is executed by a DSP which is designed to calculate floating points at very hight speed. Finally, the validity of this filter using the predictive current control method is demonstrated through experimental results.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.4
• /
• pp.586-592
• /
• 2016

The current control of Continuous Conduction Mode(CCM) can be implemented by several methods: peak current control; average current control; and hysteresis control. Among these methods, the hysteresis current control is popularly applied in various converter applications because of its simplicity of implementation, fast current control response and inherent peak current limiting capability. However, a current controller with conventional hysteresis band which multiplies the current reference has the disadvantage that the modulation frequency varies in one cycle of the input voltage and, as a result, generates high switching frequency in the low input voltage section. Also it is complicated to design the input filter due to varying switching frequency. This paper proposed an optimum hysteresis-band current control method where the band is generated by using both multiplication method and sum method to maintain the modulation frequency to be nearly constant. This approach can solve the high switching frequency in the low input voltage section, and achieve easy design of input filter. The performance of the proposed converter is verified with the simulation and the experimental works.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.3 no.1
• /
• pp.61-69
• /
• 1998

In this paper, discrete current control of voltage source inverters is proposed. As a current control scheme, the constant switching frequency predictive current control is adopted and implemented with DSP microprocessor system. In particular, the proposed method is for the compensation of the control lagging due to calculation delays in the microprocessor controller. In controlling the current, the inverter output voltage saturation problem is inevitable and usually affects the current control performance. So, the saturation boundary condition of the inverter output voltage and its effects on the current controal performance of the proposed current control scheme are investigated with experiment. Finally, the proposed scheme is applied to the active power filter system and some results are described for validation.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.5
• /
• pp.690-697
• /
• 2012

Novel 8/10 bearingless switched reluctance motor, which can control rotor radial positions with magnetic force, is proposed. The motor has combined characteristics of switched reluctance motor and magnetic bearing. This paper proposes a air-gap control system method of suspending force control in a bearingless switched reluctance motor (BLSRM). The proposed radial force control scheme is independent to the torque winding current. A PI direct current control (DCC) controller and look-up table are used to maintain a constant rotor air-gap. From the analysis and the experimental results, it is shown that the proposed strategy is effective in realizing a naturally decoupled radial force control of BLSRM.

• Proceedings of the KIEE Conference
• /
• 1997.11a
• /
• pp.66-68
• /
• 1997

In this paper, our interest is the identification and control of nonlinear dynamic plant, induction motor, by using neural networks. We usually use vector control in the induction motor such as in the DC motor. When we go over the inputs of voltage source invertor, we can find that torque current and flux current couple each other in the induction motor. Before putting control inputs in the system, we should remove the coupling terms which we already know from them. But we should consider that cross coupling terms have time-varying variables. In this paper, we identified the parameter of induction motor by using neural networks and designed the controller with identified parameters. Through this procedure we obtained compensated inputs which are decoupled each other. Using induction motor currents control, we can make the d axis current hold constant value and control the q axis current at the same time.

• Proceedings of the KIPE Conference
• /
• 2018.07a
• /
• pp.522-524
• /
• 2018

A New Direct AC LED Driver has been proposed for wide output power range and precise constant current regulation using an advanced auto commutation topology. The conventional shunt regulation method provides a stepped input current shape by fixed regulation references in the linear regulator of the each channel, which results in poor current regulation and high THD. The conventional method needs to assign a linear regulator in each LED channel so that the number of linear regulator increases when extending the number of channels especially at high power application. The proposed regulation method can drive multiple switches to regulate each LED channel current by a single amplifier with sinusoidal reference so that large number of LED channel can be simply extended with less BOM cost and low THD is obtained with the accurate current regulation thanks to the sinusoidal input current control in the closed loop control. To confirm the validity of the proposed circuit, theoretical analysis and experimental results from a 20-W LED driver prototype are presented.

• Proceedings of the KIEE Conference
• /
• 1992.07b
• /
• pp.1041-1044
• /
• 1992

A solar cell should be operated at the maximum output point on the I-V characteristic curve with constant current and constant voltage in order that the solar energy be fully utilized. According to, in this paper, we describes a controller which can track the maximum power point of a solar arry using current and voltage ripple variation of step up chopper system. The control circuit is desinged such that actual current and voltage are sensed directly from the solar cell array. These two signal are then holded sampling and multiplies by a single chip multiplier.

• Proceedings of the KIPE Conference
• /
• 2004.07b
• /
• pp.713-717
• /
• 2004

This is a thesis that a quarter-brick size of 100W class open-frame type on board power module comprising telecommunication application is reported. The input voltage is established between 36 and 75 in range in order for power module to be utilized for the telecommunication application, and output were set at 3.3V and 30A. A number of parts used for transformer, inductor, and hit sink are composed of PCB in order for DC-DC converter to be lowered below 8 mm. A constant current control circuit was annexed to the system as well as basic protection prototypes such as over-voltage, over-current, and over-temperature were well considered to enhance more credibility, and were tested. As a result, high circuit performance and credibility turned out to be significant.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.3 no.4
• /
• pp.382-387
• /
• 1998

The adaptive hysteresis band current control method using neural network is proposed to hold the switching frequency of PWM inverter constant at any operating points of ac motor. The adaptive hysteresis band equation is derived as the teaching signal of neural network. and then the structure and learning algorithm of the neural network a are suggested. The simulation results show that the switching frequency of PWM inverter is held constant at any operating conditions of ac motor and the proposed method has good transient performance of stator current.

• Proceedings of the KIPE Conference
• /
• 1998.07a
• /
• pp.234-238
• /
• 1998

Parameter estimation of induction motor for vector control presented in this paper can be easily implemented and applied to inverters in the industrial field, because it needs no additional hardware such as voltage sensor and measuring equipment. At first, the stator resistance including switching loss of inverter is measured by simple voltage-current equation. Next, in pre-magnetization of machine by imposing the d-axis constant field-current, q-axis torque current is forced to the machine until its speed feedback reachs to pre-defined level of speed limit. At this time, we can measure the rotor time-constant by decreasing the distorted output-voltage of inverter. At last, stator inductance, transient inductance, and moment of inertia can be measured by the relationship of output voltage, output torque and speed feedback. The validity and usufulness of this method is verified by experimental results.