Jun Lee

Modeling, analysis and design of 10 kW parallel module zero-voltage zero-current switched full bridge PWM converter

In this paper, the modeling and the design of the 10 kW parallel module converter are presented. Due to the high input voltage and power level, IGBTs are selected for the switching devices. The ZVZCS techniques enable the ZVZCS FB-PWM topology to operate at the switching frequency of 40 kHz, while maintaining an efficiency of over 94% at full load. The parallel scheme featuring power sharing and interleaving offers reduction of the overall system size and improvement of dynamics and EMI characteristics. A complete small-signal model for the ZVZCS FB-PWM converter employing the charge control is developed. The design equations and model predictions are verified by experimental results.

Analysis and design considerations of zero-voltage and zero-current-switching (ZVZCS) full-bridge PWM converters

In this paper, a detailed analysis of the zero-voltage and zero-current-switching (ZVZCS) full-bridge PWM converters is performed. The differences of the zero-voltage-switching (ZVS) operation between the conventional ZVS full-bridge PWM converters and the ZVZCS full-bridge PWM converters are analyzed in depth. Circuit parameters that affect the soft-switching conditions are examined and the critical parameters are identified. Based on the analysis, practical design considerations are presented. The analysis and design considerations are verified by experimental results from a 630 V/4 kW converter operating at 80 kHz.

Design of Peak and Charge Current-mode Control for Parallel Module Solar Array Regulator System

In general, the current mode controller is used to share the current in the parallel operation of a power stage. However, the parallel operation of the solar array regulator system (SAR) should be carefully designed because of the nonlinear characteristic solar array (SA), such as a negative dynamic resistance (r s ) and a SA V-I curve. In the post works, the detailed analysis of stability and dynamics of the SAR system employing current mode control has been not carried out. For these works, the SAR system employing current mode control was analyzed and compared using both large and small signal approaches. From the results of analysis, the stability problems and design issues of the SAR using current mode control for parallel operation were investigated. Finally, the considered problems and issues were tested for the verification through experiments.

Digital Control of the Parallel Interleaved Solar Array Regulator Using the Digital Signal Processor

In this paper, a digital control approach for the parallel interleaved solar array regulator (SAR) is proposed. The proposed control scheme achieves stable operation in the entire region of the solar array (SA). Additionally, by making the effective load characteristic of the SAR seen by the SA as a resistive load sink, the current sharing among the converter modules is possible. Also, this method can be applied to conventional parallel buck and boost converters. The small signal analysis with the digital sampling effect is performed. A SAR system that consists of two 100W parallel module buck converters with a TMS320F2812 DSP has been experimented using a real 200W solar array to validate the proposed digital control scheme.

Development of the control logic for the 42 V HEV system

Due to the increase of electric power payloads in todays vehicles, the 42 V power system has been considered and is being developed to replace the existing 14 V power system. It significantly improves the problems associated with the alternator and wiring harness because of the increase in the current level. The currently developing 42 V PowerNet system employs a mild-hybrid concept using the ISG (integrated starter and generator). It features the idle stop/start functions and recovers the regenerative energy during braking to improve the fuel economy and to reduce the emission. In this paper, the control logic for the currently developing 42 V system is proposed. Firstly, this work sets the system modeling suitable for the development of the control logic. Secondly, the operation mode (state) that can exist at the vehicles operation profile and the transient condition among the states are defined. Thirdly, the energy management strategy applied to the developing vehicle is proposed. Finally, it estimates the fuel economy by simulation when the proposed control logic is applied. The developed control logic is implemented and verified for the experimental HEV system

Direction Priority Control Method for Magnetic Manipulation System in Current and Voltage Limits

Magnetic manipulation system generates a magnetic field and gradient so that it can control the position and attitude of the microrobot, a magnetized agent of size under 1 mm. The system generates the force, torque, and magnetic field with currents. To date, no adjustment method concerned with voltage and current limits for the current controller of the system is researched. This paper proposes a control method that multiplies a ratio with all current or voltage references, making the largest one bounded to the rated value. Modified force, torque, and magnetic field commands are scaled down from the original ones keeping the same directions, respectively. Such adjustment may degrade the control performance but helps to control the position and attitude of the microrobot without distortion. Detailed adjustment steps considering gravity compensation and voltage feedforward terms are proposed. Simulative and experimental comparisons between two reference adjustment methods are done.

Control method considering current and voltage limits in magnetic manipulation systems

This paper proposes a control method for magnetic manipulation system which has voltage and current limits on its actuator circuits. The proposed method modifies current and voltage references making the largest ones bounded in the rated values for delicate attitude control. When current or voltage larger than the rated value is required for a force-torque command, the method generates the modified currents and voltages. Modified references make force and torque with the same direction and decreased magnitude with the original command. An actuator system with the proposed method may have slower control performance but achieves delicate attitude control. Simulative comparison between the proposed method and a simple limiting method, which simply cutoffs references, is done.

System conditions monitoring method for a wireless cellular phone charger

This paper presents a technique to be used for the cellular phone charger. The proposed technique identifies system conditions to control the output voltage, measuring only the primary side voltage and current. The method estimates the load and the coupling coefficient of the circuit by perturbing the operating frequency. The control method, designed in Primary-Series-Secondary-Series (SS) topology maximizes the efficiency by working at the resonant frequency, hence the output voltage is controlled by the switching duty cycle. The way to get the required duty cycle is proposed by this paper.

On-line position and attitude estimation for magnetic manipulation system

In this paper, on-line position and attitude estimation method for magnetic manipulation system is introduced. Based on the latest position and attitude, the force and torque applied to the microrobot are estimated with sensed currents, and the position and attitude are updated with the known plant of the microrobot environment. Magnetic flux and gradient generated by each coil are calculated by modeling each coil as a magnetic dipole. The effectiveness of the suggested method is verified with a 4-coil system; microrobot was able to move along a given circular path when using the position and attitude estimator whereas it could not when the estimator was removed.

Virelessly powered coil-type robot with 1D self-actuation capability

This paper proposes a system that can actuate itself with wirelessly received power. The system consists of two coils with different purposes; the power-receiving coil wirelessly receives power from the external sinusoidal magnetic field, and the actuation coil controls the current for 1D self-actuation. The actuation current has a square waveform and is controlled to be in phase with the external magnetic field. The average force applied to the robot is proportional to the magnitude of the actuation current. In order to improve the control performance, the actuation coil is designed with the consideration of the flux distribution. By the design, the external magnetic field does not induce a voltage on the actuation coil. The proposed design and control were verified with the implemented cylindrical prototype robot which had 18 mm radius and 34 mm height.