Toshihiro Sawa

A wide constant power range vector controlled AC motor drive using winding changeover technique

A high-performance vector-controlled induction-motor drive with a very wide constant power range of 1:10 to 1:30 has been developed for use in spindle drives of machine tools. The motor has two combinations of winding connections, and one of them is selected in accordance with the operating conditions. Using this technique, the gear box in the spindle drives is eliminated. Theoretical analysis and test results are presented.<<ETX>>

Integrated Filters and Their Combined Effects in Matrix Converter

Matrix converter has a topology that inherently exhibits sinusoidal input current waveforms and has small output voltage steps. This paper proposes to integrate the matrix converter with filters, which provide lower EMI, lower common-mode current, lower shaft voltage, and sinusoidal output voltage waveforms. A salient aspect of the proposed integration is its ability to significantly reduce the value of the input EMI filter capacitors and still meet strict EMT regulations. This helps in reducing the ground leakage current, which in the past has been a serious limitation in applying EMI filters with low ground currents for human and cattle safety.

A high-speed vector-controlled spindle motor drive with closed transition between with encoder control and without encoder control

A 40000-r/min vector-controlled induction motor drive is introduced. The vector control of induction motors has been widely accepted in spindle drives of machine tools where they replace conventional DC motors because of the low maintenance requirements. Another important feature of the AC spindle drive is its high-speed capability. The magnetic encoder is most widely used as the speed detector because it is suited for use in an adverse environment. However, the magnetic encoder with high resolution and a high S/N ratio loses the output pulses at extremely high speed. In the drive system introduced, the conventional vector control is used in the low-speed range, and the vector control without the encoder is used in the high-speed range. Close transition between two modes is made without interrupting the operation. >

Integrated filters and their combined effects in matrix converter

A matrix converter has a topology that inherently exhibits sinusoidal input current waveforms and has small output voltage steps. This paper proposes to integrate the matrix converter with filters, which provide lower electromagnetic interference (EMI), lower common-mode current, lower shaft voltage, and sinusoidal output voltage waveforms. A salient aspect of the proposed integration is its ability to significantly reduce the value of the input EMI filter capacitors and still meet strict EMI regulations. This helps in reducing the ground leakage current, which in the past has been a serious limitation in applying EMI filters with low ground currents for human and cattle safety

Introduction to the Permanent Magnet Motor Market

According to the Kyoto Summit on global warming (COP3) in December 1997, the green-house gas emission level has to be reduced to 92–94% of the 1990 green-house gas level by the year 2014-2018. This would require conserving energy. An efficient means of achieving this voluntary goal is by employing high-efficiency drives, since motors consume 70% of all electricity for industrial use in Japan.

High speed vector control without encoder for a high speed spindle motor

A 40000 RPM vector-controlled induction motor drive is introduced. In a previous paper by T. Kume et al. (see Proc. IPEC 1990 conf., Tokyo, p.1132-1136, 1990), conventional vector control with a shaft encoder was employed in a low-speed range, while constant V/f (volt-per-hertz) PWM control was employed in a high-speed range. The two control modes were switched at approximately 20000 RPM. By employing phase compensation and instantaneous current limit, the dead-time between two modes was minimized. This technique is further improved by the authors. The constant V/f PWM control in the high-speed range is replaced by vector control without an encoder. The current control loop is not interrupted for mode changing, and thus continuous operation over the entire range is established.<<ETX>>

Power-electronics contributing to the Green and Clean World

Invention of the electric motor has since, spurred its wide spread application to convert electrical energy in to mechanical work. As its usefulness grew, engineers were challenged to develop control techniques to match the speed and torque of the motor to that of the driven load to achieve optimal performance. The advent of Power Electronics was crucial in achieving variable speed operation of motors. Hence, it can be said that Power Electronics has contributed to the prosperity of todays worldwide economy and allowed people to lead a joyous and peaceful life. However, at the same time, the amount of electrical energy consumed by electric motors accounts for the We have to be aware of this fact and its consequential influence on global warming. This paper discusses variable speed motors drives. It reviews Yaskawas contribution to industrial inverter drives and introduces a technology road map to realize a “Greener World” with all its future prospects.