Joon-Min Lee

Electrolytic capacitor free and reduced 120[Hz] ripple on the output of a single-stage CCM flyback converter with power factor correction for LED lightings

Interest of light emitting diode (LED) lightings is more and more increased because of its low power consumption and long lifetime. Generally, the LED lighting is driven by a power converter. Electrolytic capacitors are used for stabilizing the output ripple of the power converter. However, the expected lifetime of electrolytic capacitors is very shorter than LED or other components in the power converter. As the result of that, expected life time of LED lighting is decreased. In this paper, a single-stage CCM flyback converter without electrolytic capacitors is proposed. The proposed converter is verified through simulations and experiment.

The Dimmable Single-stage Asymmetrical LLC Resonant LED Driver with Low Voltage Stress Across Switching Devices

In the LED lighting industry, the dimming function in the LED lamp is required by demands of many consumers. To drive this LED lighting, various types of power converters have been applied. Among them, an LLC resonant converter could be applied for high power LED lighting because of its high efficiency and high power density, etc. The function of power factor correction (PFC) might be added to it. In this paper, a dimmable single-stage asymmetrical LLC resonant converter is proposed. The proposed converter performs both input-current harmonics reduction and PFC using the discontinuous conduction mode (DCM). Also, the lower voltage stress across switching devices as well as the zero voltage switching (ZVS) in switching devices is realized by the proposed topology. It can reduce cost and has high efficiency of the driver. In addition, the regulation of the output power by variable switching frequency can vary the brightness of a light. In the proposed converter, one of the attractive advantages doesn’t need any extra control circuits for the dimming function. To verify the performance of the proposed converter, simulation and experimental results from a 300W prototype are provided.

Control of the Bidirectional DC/DC Converter for a DC Distribution Power System in Electric Vehicles

Recently, an electric vehicle (EV) has been become a huge issue in the automotive industry. The EV has many electrical units: electric motors, batteries, converters, etc. The DC distribution power system (DPS) is essential for the EV. The DC DPS offers many advantages. However, multiple loads in the DC DPS may affect the severe instability on the DC bus voltage. Therefore, a voltage bus conditioner (VBC) may use the DC DPS. The VBC is used to mitigate the voltage transient on the bus. Thus, a suitable control technique should be selected for the VBC. In this research, Current controller with fixed switching frequency is designed and applied for the VBC. The DC DPS consist of both a resistor load and a boost converter load. The load variations cause the instability of the DC DPS. This instability is mitigated by the VBC. The simulation results by Matlab simulink and experimental results are presented for validating the proposed VBC and designed control technique.

Sensorless Fuzzy MPPT Control for a Small-scale Wind Power Generation System with a Switched-mode Rectifier

A small-scale wind power generation system with a switched-mode rectifier(SMR) is proposed. To simplify the converter circuit of the wind power generation system, the synchronous inductors of the permanent magnet synchronous generator(PMSG) replace the inductor for the boost converter. The sensorless maximum power point tracking(MPPT) control is carried out for the wind power generation system with the SMR. The proposed system is verified through the simulations and the experiments.

The MPPT Control Method of the PMSG Wind Generation System using the Turbine Model with a Squirrel Cage Induction Motor

This paper presents the MPPT(Maximum Power Point Tracking)control method of the PMSG wind generation system using the turbine model with a squirrel cage induction motor. The torque of squirrel cage induction turbine model is controlled by mathematization of speed characteristics of real blade. In this paper, maintenance and cost issues into consideration, except for previous method using information of the velocity of the wind speed sensor, the algorithm is presented. The algorithm is controlled by tracking the optimal point, the generator speed and maximum grid power. The vector controls of the generator side converter and the grid side converter are controlled respectively to obtain maximum torque and regulate unity power factor. With Psim simulations and experiments, the efficiency of squirrel cage induction turbine model and the validity of control algorithm are verified.

A Sensorless Control of IPMSM using the Adaptive Back-EMF Estimator and Improved Instantaneous Reactive Power Compensator

This paper propose a sensorless control system of IPMSM with a adaptive back-EMF estimator and improved instantaneous reactive power compensator. A saliency-based back-EMF is estimated by using the adaptive algorithm. The estimated back-EMF is inputted to the phase locked loop(PLL) and the improved instantaneous reactive power(IRP) compensator for estimating the position/speed of the rotor and compensating the error components between the estimated and the actual position, respectively. The stability of the proposed system is achieved through Popov’s hyper stability criteria. The validity of proposed algorithm is verified by the simulations and experiments.

Direct torque control of permanent magnet synchronous motor using a sliding-mode observer

This paper proposes that direct torque control of interior permanent magnet synchronous motors (IPMSM) using a sliding mode observer (SMO). The sigmoid function is used to decrease the chattering as the switching model. This function is more effective than the unit step function to decrease the chattering. The back-EMF component of the motor is observed for robust sensorless control. The rotor position is detected from the observed back-EMF component and phase-locked loop method for estimating accurate position of the rotor and speed of the motor is applied. The validity of the proposed control scheme through simulations is confirmed.

V/f control of the SPMSM with the stabilizing loop using a reduced order observer

This paper proposes a sensorless V/f control method of the surface mounted permanent magnet synchronous motor without damper windings. Arithmetic computation is simpler than vector control. And the low cost price, dynamics and stability is guaranteed. When the loss of synchronization occurs with the load disturbances, the stability loop with a reduced order observer is applied quickly and accurately to improve the speed error.

Improved instantaneous reactive power compensator applied sensorless control of IPMSM with adaptive back EMF and current model observer

This paper presents the sensorless control method that employs the adaptive back-EMF(Electromotive Force) and current model observer(CMO) of interior permanent magnet synchronous motor(IPMSM) with improved instantaneous reactive power compensator(IRP). The estimated back EMF considering a saliency is obtained by using the adaptive control method. The estimated EMF is inputted to the CMO for estimating the position and speed of the rotor. In order to improve the shortcomings of conventional compensation method with IRP, the modified instantaneous reactive power compensator which is considering the saliency-based EMF is applied. The validity of the control system presented is verified by the simulation.