Hisao Kubota

DSP-based speed adaptive flux observer of induction motor

A method of estimating the speed of an induction motor is presented. This method is based on the adaptive control theory. Experimental results of a direct field oriented induction motor control without speed sensors are presented.<<ETX>>

Speed sensorless field oriented control of induction motor with rotor resistance adaptation

The authors present a method for estimating simultaneously the motor speed and the rotor resistance of an induction motor by superimposing AC components on the field current command. In addition, a rotor resistance adaptive scheme is proposed in order to decouple the rotor resistance adaptation with the motor speed variation. The validity of the proposed method has been verified by simulation.<<ETX>>

Regenerating-mode low-speed operation of sensorless induction motor drive with adaptive observer

Speed estimation methods for sensorless induction motor drives can be divided into two groups. One is based on information about fundamental components of stator currents and voltages. The other is based on high-frequency components injection in stator voltages or currents. The latter may operate stably under zero frequency, which occurs in regenerating mode at low speeds. It, however, causes loss increasing and torque ripple. The former is difficult to operate under zero frequency. The authors propose a stable method categorized in the former group even in regenerating mode at low speeds. The proposed method is based on an adaptive flux observer. First, a new observer gain design is shown. Next, a method avoiding zero-frequency operation with controlling a rotor flux level is proposed.

New adaptive flux observer of induction motor for wide speed range motor drives

A flux observer of an induction motor with a parameter adaptive scheme is proposed. The parameters identified adaptively are stator and rotor resistance, which vary with motor temperature. The stability of the proposed adaptive flux observer is proved using Lyapunovs theorem. The robustness of the induction motor drive system with the proposed flux observer is shown. The adaptive scheme can also be applied to estimate motor speed without speed sensors.<<ETX>>

Study of the Magnetization Method Suitable for Fractional-Slot Concentrated-Winding Variable Magnetomotive-Force Memory Motor

This paper describes a variable magnetomotive-force memory motor with a fractional-slot concentrated winding. We propose a method for optimal control of magnetization suitable for a fractional-slot concentrated winding. Our result shows that variable magnetized magnets are more highly magnetized when a fractional-slot concentrated winding is used than those using the conventional method.

Speed sensorless field oriented control of induction machines using flux observer

Speed sensors are required for the field oriented control of induction machines. These sensors reduces the sturdiness of the system and make it expensive. Therefore, a drive system without speed sensors is required, This paper reviews speed sensorless induction motor drive methods using flux observers including Kalman filters.<<ETX>>

Stable operation of adaptive observer based sensorless induction motor drives in regenerating mode at low speeds

Sensorless induction motor drives can be divided into two groups. One is based on fundamental components. The other is based on high frequency components injection. The latter may operate stably under zero frequency, which occurs in regenerating mode at low speeds. It, however, causes loss increasing and torque ripple. The former is difficult to operate under zero frequency. The authors propose a stable method categorized in the former group even in regenerating mode at low speeds. The proposed method is based on an adaptive flux observer. First, a new observer gain design is shown. Next, a method avoiding zero frequency operation with controlling a rotor flux level is proposed.

Behavior of sensorless induction motor drives in regenerating mode

This paper presents two kinds of sensorless vector control methods of induction machines which work stably even in the regenerating mode. These methods work by taking the stator resistance variation into account.

The improvement of performance at low speed by offset compensation of stator voltage in sensorless vector controlled induction machines

The speed range for sensorless vector controlled induction machine drives is limited to about 1:100 in industry. The main reason for this limitation is inaccuracy of stator voltage regulation. The lower the motor speed becomes, the lower the stator voltage becomes. Therefore, it is difficult to regulate or measure the stator voltage precisely at low speed, and difficult to control motor speed and motor torque precisely. This paper presents a method of improving the low speed performance of sensorless vector controlled induction machine drives by offset compensation of the stator voltage. The offset is compensated by using the fluctuation of the estimated rotor flux. The validity of the proposed method is verified by experimentation.

Investigation of IPMSM's Position Estimation in Low Speed Region with DC Link Current Detection

This paper presents a new method to estimate the pole position of an interior permanent magnet synchronous machine, IPMSM. The proposed method uses the three phase triangular carrier waves for the PWM signal generation and measures only the current of the DC link of the inverter. The DC link current can be measured with an inexpensive current sensor such as a shunt resistor. The proposed method enables to estimate the pole position at low speeds and standstill. In this paper, first, authors verify the validity of the proposed method by the experiment, and compensate the position estimation. The proposed method needs the current detection at tops and bottoms of carrier waves, precisely. So, the method is investigated in this theory about the effect of the current detection timing delay. And the ways to compensate the timing delay is explored.