Title:
PROTECTIVE DEVICE OF PERMANENT MAGNET TYPE SYNCHRONOUS MOTOR DRIVEN BY INVERTER UNIT
Document Type and Number:
Japanese Patent JPS5678393
Kind Code:
A
Abstract:
PURPOSE:To prevent demagnetization of the permanent magnet caused by overexcitation by a method wherein an overexcitation detector to stop the excitation of an electric motor is add when outputs of an integrator which operates integral calculations of the motor terminal voltages become over a prescribed value. CONSTITUTION:A converter unit 2 and an inverter unit 3 are connected to a permanent magnet type synchronous motor 4, a thyristor of the converter unit 2 is controlled by a voltage command and a thyristor of the inverter 3 is controlled by a frequency command from a reference command system 6. The motor terminal voltages are fed as inputs to a output voltage detector 13 through PT5 and one of the outputs is fed to an overexcitation detector 17 to operate integral calculations and when the calculated value becomes more than the prescribed value, gates of the respective thyristors of the inverter 3 and the converter 4 are locked. Accordingly, the overexcitations can securely be detected by the detector 17 and the demagnetization of the permanent magnet can be arrested.
Inventors:
TAMURA YOSHIMOTO
Application Number:
JP15183679A
Publication Date:
June 27, 1981
Filing Date:
November 22, 1979
Export Citation:
Assignee:
MITSUBISHI ELECTRIC CORP
International Classes:
H02P27/06; H02P25/02; (IPC1-7): H02P7/62