METHOD AND DEVICE FOR PROTECTING REGENERATIVE RESISTOR IN A DRIVING INVERTER FOR A SERVO MOTOR

摘要

A protecting method and apparatus for a regenerative resistor in which a regenerative resistor is satisfactorily protected from a thermal breakage caused by an over-regeneration by combining a protection of the regenerative resistor by a thermostat and a protection of the regenerative resistor by an analog simulation circuit and by coordinating protective regions of these two protections. The heat-responsive switch (2) stops power supply to a DC link (10) when the temperature of the regenerative resistor is increased to a predetermined value or greater value. The analog simulation circuit (1) is provided with a charge-discharge circuit to be charged and discharged in response to a regenerative pulse signal from a level detector (7), estimates the quantity of heat accumulated in the regenerative resistor (5) by means of the charge-discharge circuit, and stops power supply to the DC link (10) when a predetermined threshold value is exceeded by the estimated value. A fusing region of the regenerative resistor (5) is covered by at least one of the protective regions based on the heat-responsive switch (2) and the analog simulation circuit (1).