Jun-Seok Cho

A novel pulse power supply for magnetron using high voltage capacitor embedded high frequency transformer

This paper described that novel high voltage capacitor (HVC) embedded high frequency transformer and novel inverter power supply topology for driving magnetron in microwave oven. This transformer is used to achieve down-sizing, low-cost and efficiency improvement. Proposed transformer has HVC in its secondary winding. Therefore, this transformer does not need external high voltage capacitor which used in conventional power supply. As use of this transformer, output voltage is shifted from ground to above 2000 [V] and efficiency of microwave oven can be improved. The weight of proposed transformer is about one sixth of conventional one and efficiency is improved by seven percent compared to the efficiency of the conventional system.

Analysis of pulse power converter for plasma application

Atmospheric pressure plasma using a dielectric barrier discharge (DBD) reactor has been widely used for the surface treatment of materials, pollution abatement, disinfections, etc. A high voltage power supply is needed, however, to generate plasma in atmospheric pressure circumstances. Especially, it is widely known that the pulsed voltage can generate plasma with better quality compared to the voltage with a sinusoidal waveform. In this paper, an analysis of the pulse power converter including a dielectric barrier discharge (DBD) reactor was performed to obtain design information regarding the converter system which generates the pulsed high voltage. A pulse power converter system was fabricated and applied to a DBD reactor. The results of the simulation and experiment on the converter system that was applied to the DBD reactor are presented in this paper.

Analysis and design of modified deadbeat controller for 3-phase uninterruptible power supply

This paper proposes a modified deadbeat control scheme of 3-phase PWM inverter with LC filter for uninterruptible power supply (UPS). The deadbeat current and voltage controller are used to obtain the fast transient response of the UPS system in general. However, the conventional deadbeat controller has a defect and becomes unstable. In this paper, to remove the defect which makes a system unstable due to the same pole placement of a conventional deadbeat current and voltage controller, modified deadbeat algorithm, which produces a first-order exponential response during one input step, is proposed. Because the overall controller is constructed by deadbeat control, the response of the proposed control system is fast and the structure of the controller is simple. In addition, the full-order state and disturbance observer is constructed to compensate the disturbances generated by a sudden change of load currents. The proposed disturbance observer estimates state values of load currents within a finite time, and cancels the disturbances by adding a feedforward compensation loop in the control system. The validity of the modified deadbeat control scheme is proved by the results of simulation and experiment.

Modified deadbeat digital controller for UPS with 3-phase PWM inverter

In this paper, a modified deadbeat control scheme is proposed for 3-phase PWM inverter control such as uninterruptible power supply (UPS). The deadbeat controller, which is generally constructed with voltage and current controller in UPS, is used for fast transient response, but this might have an instability due to the same pole placement of the double controller. To solve this instability problem, separation of pole placement can be considered, and it is performed by the proposed deadbeat control scheme. In this paper, this control scheme is called the modified deadbeat, which produces a first-order exponential response during one input step. As the overall controller is constructed by deadbeat control, the response of the proposed control system is fast and the structure of the controller is simple. In addition, the disturbance observer with full-order state is constructed, which can cancel the disturbances by adding a feedforward compensating loop in the controller and hence it can compensate the disturbances caused by a sudden load change in the UPS system.

Parallel Operation Control of N+1 Redundant Inverter System

In this paper, a novel parallel operation algorithm of N+1 redundant inverter system with no control interconnections for loas-sharing is presented. The proposed control system eliminates the sensing noise and interconnection interface of conventional parallel operation system. To reduce a reactive power deviation in wireless control method, this technique automatically compensates for inverter parameter variation and line impedance imbalances with wireless auto-tuning method. In addition, to increase reliability on transient characteristics of parallel operation, a virtual injected impedance is adopted to eliminate a circulation current among inverter modules. Simulation results are provided in this paper to prove the proposed novel algorithm.