Teruo Nakagawa

A Microcomputer-Based Thyristor Leonard System Having Powerful RAS Functions

The microcomputer-based entirely digital scheme for the thyristor Leonard system is presented. The main processor used is a 16-bit microprocessor. Systematic and efficient use of the microprocessor and microcomputers successfully provides the thyristor Leonard system with the entire digital scheme. This scheme offers not only the high-performance adjustable-speed regulation of dc motors, but also other important functions and features required for the Leonard system, such as system sequencing, thyristor triggering, various compensations for improvement in electric performances, diagnostic, monitoring, and protection capabilities, drift-free characteristics, and so forth. The scheme also serves smoother communications between the microcomputer-based system and a programmable host controller, which supervise a number of Leonard systems. Compact design permits the hardware construction for the digital scheme to be accommodated on a single board.

New Application of Current-Type Inverter

It is important to take commutation and torque ripple into consideration when applying a current-type inverter to a large- capacity induction motor (pump, blower, etc.) for reducing power consumption. To solve the problems, a new multiple connected current -type inverter which has quasi-sinusoidal output current wave- form has been developed. With a view to attaining exact speed control and quick response, an induction motor vector control technique fed by a current-type inverter has been developed. Examples of these application techniques in multiple connected and vector control current -type inverters are described.