Jae-Sung Yu

A new hybrid sensorless method using a back EMF estimator and a current model of permanent magnet synchronous motor

This paper presents a sensorless method which combined a back-EMF estimator and a current model of PMSM. Sensorless method using the back-EMF estimator, because of its position estimation method, the lowest controllable speed is limited despite of the correct back-EMF estimation. On the other hands, the current model based sensorless method has the benefit that robust control for large load torque. However, the correctness of the estimated back-EMF is determined by a back-EMF coefficient which is varied by load torque and speed. For these problems, this paper proposes the hybrid sensorless method that the back-EMF estimator for precise back-EMF estimating, and the current model of PMSM for robust control and extend the controllable speed region. This method offers not only non-necessary back-EMF coefficient which should be varied, but also wide speed operating region in no specific transition method.

Analysis of a new PWM method for conducted EMI reduction in a field oriented controlled induction motor

The prevalence of EMI noise problems has been considered many times over the past few years, in inverter fed motor control systems. The advent of high speed power devices, and the high dv/dt of switching devices, has resulted in EMI problems and leakage current. This paper describes the application of the newly developed EMI reduction technique of SVPWM in induction motor drives. This newly developed common mode voltage reduction SVPWM technique does not use any zero-voltage vector states for inverter control, hence can restrict the common mode voltage more efficiently than the conventional PWM technique. The validity of the proposed technique is verified through simulation and experimental results. In this paper, by applying the vector control system, the proposed technique is presented as superior in reducing EMI and equal control performance, compared to the conventional space-vector PWM technique.

Load modeling for the drum washing machine system simulation

In this paper, we explained the load modeling of drum washing machine for determining the rating of motor drive device. The motor drive should supply enough current to motor in spite of load variation. However, drum washing machine load torque is not only affected by the weight. Besides, drum washing machine load torque has the frequency which is influenced by the drum velocity. We analyze the forces that affect the laundry. And the load torque is designed by the mathematical equation. Finally, we compare the conventional constant torque and the proposed load torque simulation.

Output voltage control of a synchronous generator for ships using compound type digital AVR

This paper deal with field current control method of a synchronous generator (SG) for ships using a compound type digital automatic voltage regulator (AVR) in order to control output voltage of the generator. The compound type digital AVR is composed of a control part to adjust output voltage and an auxiliary power unit to supply power to the field. The control part which generates the PWM switching pattern via the PI controller drives a power MOSFET for bypass to limit the synchronous generators field current. The auxiliary power unit is parallel connected to an output terminal of the generator through a reactor and power CT. The residual magnetic flux of synchronous generator provides field current to the exciter through the reactor during the initial driving or no-loading operation and load current supplies field current to the exciter flowing to the power CT when the load is connected on the system. Experimental results demonstrate the digital AVRs benefits.

Output voltage control of synchronous generator for ships using a PMG type digital AVR

In order to provide a constant output voltage at the generator terminal, the field current of a synchronous generator is controlled by automatic voltage regulator (AVR). For most of AVR in the synchronous generator for ships, it uses the way of phase control thyristor. The period of this method, however, is slower than a converter composed of MOSFET or IGBT, thereby having difficulties to implement rapid response control. In addition, regarding to the existing analogue AVR, there is a demerit that it is difficult to monitor the system so it may not provide convenience for the user. Therefore, this paper implemented a PMG type digital AVR using MOSFET on a synchronous generator for ships. Besides, the digital AVR implemented was improved for user convenience by building a monitoring system using the Labview software. The system studied was verified its validity through a 10[kVA] prototype experiment, instead of using an actual generator for ships.

Permanent Magnet Synchronous Motor Vector Control Using Rectangular 2 Hall Sensors

This paper proposes a new vector control method using two rectangular hall sensors instead of using the expensive encoder and resolver. The proposed method estimates the speed and motor position by using the quadruple of two hall sensors signals instead of encoder signal. The proposed new speed estimation method is stable under the rated speed range. This algorithm will be able to moderate prices of the whole system and apply to the condition unfitted with encoder and resolver.

A four-switch and half-bridge boost converter based BLDCM drive system for the DC-link voltage unbalancing compensation

This paper proposes a controller to compensate the DC-link voltage unbalance in the BLDC motor drive system based on the four-switch and half-bridge boost converter. In this paper, we can see that the proposed feedforward controller is useful for control of the neutral point voltage unbalance. The comparative experimental results show that the system became more robust by the feed-forward control of the neutral point voltage.

Control of IPMSM drive system for drum washing machine

The drum washing machine needs high torque than the other types of washing machine because of the large load torque variation. Therefore, in this paper, we applied a interior permanent magnet synchronous motor (IPMSM) to the drum washing machine system. However, IPMSM operate at lower output torque than the other permanent magnet synchronous motor (PMSM) when the motor control is performed by the conventional control method. This paper suggests adaptive control method for IPMSM to obtain better torque performance and apply the control method in actual experiments of the drum washing machine system.

Simulation model for a seven-phase BLDCM drive system

BLDC motors have many advantages over brushed DC motors and induction motors. So, BLDC motors extend their application to many industrial fields. In this paper, the digital simulation and modeling of a 7-phase brushless DC motor have been presented. The 14-switch inverter and a 7-phase brushless DC motor drive system are simulated using hysteresis current controller and logic of switching pattern with the Boolean¡s function. Through some simulations, we found that our modeling and analysis of a 7-phase BLDCM with PWM inverter would be helpful for the further studies of the multi-phase BLDCM drive systems.