g-Joo Byen

Design of Leakage Inductance in Resonant DC-DC Converter for Electric Vehicle Charger

In this paper, the electric charger with single phase PWM converter and a bidirectional half-bridge converter is proposed. A transformer leakage inductance is used for making resonance at the resonant converter, which can make switched current to be sinusoidal without extra inductive component. Both operating principle and design guideline are described in detail. The feasibility for the proposed design is verified through hardware implementation and the experimental results. Detailed results have been obtained to show several advantages such as the compact design and reduced switching losses for different values and conditions of leakage inductance and resonance cases.

A high-efficiency variable modulation strategy for a dual-active-bridge converter with a wide operating range

This paper proposes a variable modulation strategy for a dual-active-bridge (DAB) converter with a wide operating range to achieve high efficiency. In the propose method, four voltage modulation strategies are automatically changed for efficiency optimization under the operating voltage and the output power. To do this, the boundary conditions of each modulation region are derived to minimize the power loss, and a seamless mode transition algorithm between each modulation strategy is introduced. A 3kW DAB converter whose primary voltage is 380V and the secondary voltage ranges from 100V to 500V has been built. The experimental results show that the DAB converter with the proposed modulation strategy achieves peak 98.9% peak efficiency under 400V output voltage condition.

A capacitor current control for stand-alone inverters using an inductor current observer

This paper discussed an inductor current observer design that employs a capacitor current control model for single-phase stand-alone inverters. The single-phase stand-alone inverter is analyzed via modeling. The proposed solution is able to guarantee a fast dynamic response and also a precise compensation of a distortion load. Moreover, with a proper design of observer parameters, it is possible to build a precise inductor current information without the inductor current sensor. The simulation and experimental results show that the performance of the proposed controller.

Load Disturbance Compensation for Stand-alone Inverters Using an Inductor Current Observer

A control scheme for stand-alone inverters that utilizes an inductor current observer (ICO) is proposed. The proposed method measures disturbance load currents using a current sensor and it estimates the inductor current using the ICO. The filter parameter mismatch effect is analyzed to confirm the ICO’s controllability. The ICO and controllers are designed in a continuous-time domain and transferred to a discrete-time domain with a digital delay. Experimental results demonstrate the effectiveness of the ICO using a 5-kVA single-phase stand-alone inverter prototype. The experimental results demonstrate that the observed current matches the actual current and that the proposed method can archive a less than 2.4% total harmonic distortion (THD) sinusoidal output waveform under nonlinear load conditions.

High-Performance Voltage Controller Design Based on Capacitor Current Control Model for Stand-alone Inverters

This study proposes high-performance voltage controller design that employs a capacitor current control model for single-phase stand-alone inverters. The single-phase stand-alone inverter is analyzed via modeling, which is then used to design the controller. A design methodology is proposed to maximize the bandwidth of the feedback controller. Subsequently, to compensate for the problems caused by the bandwidth limitations of the controller, an error transfer function that includes the feedback controller is derived, and the stability of the repetitive control scheme is evaluated using the error transfer function. The digital repetitive controller is then implemented. The simulation and experimental results show that the performance of the proposed controller is high in a 1.5 kW singlephase stand-alone inverter prototype.

Parallel PCS Interconnection Current Surge Elimination Technique Using a Coupled Inductor

In this paper, coupled inductor method in parallel operation of PCS is proposed. In coupled inductor the primary and secondary currents flow in the same direction, the total flux total inductance is cancelled. However, when the currents flow in the opposite direction, each flux becomes an individual inductor. Aforementioned characteristic is adopted in parallel operation of PCS. Abnormal current is blocked by coupled inductor which is barred to connect grid code. A design guide is suggested by PCSs capacity and the circulation current duration time. The proposed design is verified through the hardware implementation and experimental results that show the effectiveness of variance reduction.

A new hybrid distribution system interconnected with PV array

Nowadays, due to the increase of the digital product which can be operated in dc voltage, the use of dc power has increased inside the electric appliances. As the appliances has been equipped with ac/dc converter to supply the driving voltage of dc voltage by ac/dc converter, there could occur the problems such as poor power factor, harmonic increase of the input current and the conversion loss. The hybrid distribution (HBD) system proposed in this study indicates the total system which is supplied to the all AC and DC loads at home by the renewable energy of PV system together with AC commercial source from the utility. In this paper is verified the operation principle and the feasibility of the designed HBD system. The twin systems are set up for the comparison of the conventional AC system and the proposed HBD system linked under the same conditions. Particularly the distribution efficiency, power factor and harmonic characteristics are investigated.

Dual SRF based torque ripple mitigation strategy for a fault tolerant PMSM drive system

This paper presents a torque ripple mitigation strategy for the fault tolerant permanent magnet synchronous motor (PMSM) drive system, in which an auxiliary phase is employed. It is shown that the torque ripple whose frequency is twice the fundamental frequency is induced in the PMSM undergoing an open circuit fault on a certain phase. In order to compensate the torque ripple, current controllers are implemented in the dual synchronous reference frame (SRF), in which the rotating frequencies of the two SRF are different. In more detail, one of the SRFs rotates in two times of the fundamental frequency to actively compensate the torque ripple in the steady state while another one is synchronized to the fundamental component. Compared to traditional methods, the proposed algorithm effectively extends the operating speed of the PMSM where the torque ripple can be compensated. Both the simulations and the experimental results confirm the usefulness of the proposed torque ripple mitigation strategy.

A Study on Residential Hybrid Distribution System for Reducing Power Conversion Loss

This paper proposes residential hybrid distribution system that can supply AC power and DC power to AC load and DC load at the same time. This hybrid distribution system consists of three parts: bidirectional inverter, step-up converter and step-down converter. Also that is used to supply voltage to home application is classified of AC load and DC load as load characteristics. The performance of proposed hybrid distribution system is validated through the hardware implementation and the experimental results.

A Seamless Mode Transfer Scheme for Single Phase Inverter with ESSs

This paper proposes a mode transition algorithm between the grid-tied and the stand-alone operations for the single-phase inverter with the energy storage system. For the grid-tied operation, the dc-link voltage and the output current are required to be control. For the stand-alone mode, both the output voltage and the output current should be regulated. In order to mitigate a falling-off in control performance during transients in mode change, the load power estimation and the current selection schemes are proposed. The proposed method allows an optimized current reference is selected to reduce an output voltage drop and an excessive over-current in transient. To verify the effectiveness of the proposed method, both the simulation and the experiments for a 3kW single-phase inverter with the energy storage system have been conducted. From the results, it has been confirmed that the proposed method reduces a transient error as well as implementing smooth mode transition.