| 摘要 |
PROBLEM TO BE SOLVED: To protect a motor against burning by operating temperature rise of the motor accurately while taking account of the rotational frequency of the motor. SOLUTION: The protector for main motor of vehicle comprises a multiplier means 22 for obtaining the square of a current being fed to a motor 4 from a torque component current detecting means 7 based on an output signal therefrom, a function generating means 27 having a radiation table matching with the radiation time constant of the motor dependent on the rotational frequency of the motor, means 26 for summing and integrating output signals from the multiplier means 22 and the function generating means 27, a pulse generating means 21 for turning both output signals on/off at a specified interval, and a comparator 28 for comparing the output signal from the integrating means 26 with a preset temperature to generate an alarm output 29. The comparator 28 is set with upper and lower temperature rise limits and a recovery mode is cut when the lower limit is reached while operation of a VVVF inverter is stopped when the upper limit is reached. |
