This paper presents a hybrid PM(Permanent Magnet) generator which is consisted with a winding and assistant PM for the field flux. The field flux of the generator is combined by the permanent magnet and the field current together. In the no-load condition, the flux of the assistant PM is enough to generate the output voltage. And the flux from the field current can compensate the voltage drop by the load injection of the generator. In order to use the conventional generator system, the assistant PM part is mechanically installed with the conventional rotor of the generator. The proposed generator can be modified by the conventional generator with the assistant PM rotor to improve the efficiency. The proposed PM assistant hybrid generator is verified by the FEM analysis and the experimental results.
Predictive current control in the synchronous reference frame with back EMF estimation using previous voltages and currents is presented. To reduce the torque harmonics produced by the harmonics in the air gap flux by an online set-up, the d-axis and q-axis currents are compensated. The compensated harmonic currents are derived by using the estimated flux linkage harmonics which are derived from the estimated back EMFs. The effectiveness of the proposed control scheme is compared to the conventional one through the simulation and experiments.< >
This paper presents a multiple predictive direct torque control - pulse width modulation (MPDTC-PWM) control method for permanent magnet synchronous motor (PMSM) using a 12-sector division and 12 voltage vectors. In the proposed method, the voltage vectors can be obtained by the multiplication of estimated torque and flux error based on a mathematical model of the motor. Both back EMF and decoupling factor are considered to select the proper voltage vector to reduce the torque ripple in PMSM. The candidate voltage vectors obtained from torque and flux errors may not all be suitable, depending on the motor speed and actual torque. This is caused by back EMF and decoupling effect. In the 12-sector division method, the switching voltage vector and PWM duty ratio can be obtained by the estimated torque ripple according to the switching state of the voltage vector. Simulation results show that the proposed MPDTC-PWM for PMSM resulted in an excellent control performance with reduced torque ripple which was achieved through the optimization of vector selection process.
In this paper, a variable reference speed control of a high-speed Brushless DC(BLDC) motor for blender machines is proposed for reducing the speed ripple at the high-speed pulsating load variation condition. A high-speed 2-pole BLDC motor is designed to satisfy the operating speed and the efficiency of the blender machine. According to the pulsating load, the motor speed is pulsated by the conventional current limit control scheme in the constant power region. In order to improve the grinding performance, the reference speed is automatically varied to overcome the pulsating load variation in the proposed method. From the reference speed control, the output torque of the motor can satisfy the pulsating load of the blender machine. The designed high speed BLDC motor and the proposed control scheme are verified by simulations and experiments.
This paper presents the design and control of a rail guided mover system using a brushless dc (BLDC) motor as traction. In the designed system, the roller on the rail surface is driven by the BLDC motor, and the high-definition camera moves up and down driven by a dc motor. In order to keep the reference position in the low-speed region around the stop position, a modified microstepping method using torque angle is proposed. The proposed microstepping method uses the variable current magnitude according to the estimated torque angle in order to reduce the torque ripple. Then, the actual rotor follows the rotating current vector with the proper torque angle band. Moreover, a smooth deceleration is achieved by a variable gain of the position controller, which is obtained by the deceleration time and position error. Furthermore, the slip effect between the roller and the rail surface is simply compensated by the measured slip coefficient in both forward and backward directions. The proposed position control method is verified by the experiments of the practical rail moving security system.
This paper presents a simple predicted current control scheme for BLDC(Brushless DC) motor to reduce the torque ripple in the commutation and conduction region.
This paper presents a novel arbitrary curved path control scheme to reduce the unbalance load between traction motors and position error at the designed rail-guided surveillance system. The designed rail-guided surveillance system is controlled by the two BLAC(Brushless AC) motors based on the internal hall position sensor without any external rail position sensors. Because of the arbitrarily curved guide rail, the traction loads of the inner and outer motor become different due to the mechanical friction of the inner side. Furthermore, the position error also increases. In order to reduce the unbalance load and improve the driving performance at the arbitrarily curved guide rail, the differential of estimated heading angle from IMU(Inertia Measurement Unit) is used to calculate the difference moving length between the inner and outer side motors. At every 2ms sampling period, the compensated moving length references of the inner and outer side motor are updated according to the change of the estimated heading angle. The compensated moving length references control the moving speeds of the inner and outer motor to improve the curved driving performance. In the practical experimental verification, the proposed control scheme shows advanced driving and excellent position control performance for the designed rail-guided surveillance robot.
This paper presents a design and control of the rail mover system for the security system of the wide area. The rail mover is driven by the geared BLDC(Brushless DC) motor on the rail surface. The position of the rail mover body has to be controlled at the correct position during the running on the rail surface. In this paper, the BLDC motor with hall sensor is used to control of the position. Because the speed estimation from the hall sensor is not accurate in the low speed region, the accurate position control is very difficult. Furthermore, the actual position and the motor position are not same due to the slip effect on the rail surface and driving roller. In order to overcome these problems, an accurate micro-angle control scheme in the low speed range and slip compensator are proposed in this paper. The proposed micro-angle control scheme uses the reference angle from the reference speed with the torque angle compensation. The advanced rotating flux in the low speed region to keep the actual position is based on the reference speed and angle. But the actual rotor position and speed are used to control the motor speed in the normal speed range. The two sensors which are attached to the side of the mover are used to compensate the slip error during the forward and backward moving. The virtual position is derived by the slip error which is calculated by the side sensor of the body can reduce the actual error of the rail. The proposed control scheme and designed mover are verified by experiments of the manufactured rail mover system.
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