MOTOR DRIVING DEVICE INCLUDING DYNAMIC BRAKING CIRCUIT

摘要

A motor driving device includes, a DB current calculation unit which calculates a DB current flowing through a DB circuit, based on the motor rotational speed and intrinsic parameters for a motor and the DB circuit, a Joule heat calculation unit which calculates a Joule heat resulting from a DB current, based on the DB current, a storage unit which stores a table defining the relationship between the DB current at the start of DB and the Joule heat resulting from an arc generated in a relay depending on the DB current, an integration unit which integrates the Joule heat resulting from an arc at the start of DB, the Joule heat resulting from a DB current, or the sum of these Joule heats, every time DB is performed, and a comparison unit which outputs the comparison result between the resultant integration value and a predetermined reference value.

主权项

1. A motor driving device comprising a dynamic braking circuit which closes a relay located across input terminals of a motor to cause a resistive short circuit across the input terminals to generate a deceleration torque in the motor, the device comprising:
a dynamic braking current calculation unit which calculates a value of dynamic braking current flowing through the dynamic braking circuit, based on a motor rotational speed and a parameter predefined for the motor and the dynamic braking circuit; a Joule heat calculation unit which calculates a Joule heat resulting from a dynamic braking current supplied to a contact of the relay in a dynamic braking period, based on the value of dynamic braking current obtained by the dynamic braking current calculation unit; a storage unit which stores in advance a table defining a relationship between a value of dynamic braking current at start of dynamic braking and a Joule heat resulting from an arc generated in vicinity of the contact of the relay depending on the value of dynamic braking current at the start of dynamic braking; an integration unit which integrates one of a Joule heat resulting from an arc and obtained from the table as a Joule heat corresponding to the value of dynamic braking current obtained by the dynamic braking current calculation unit at the start of dynamic braking, a Joule heat resulting from a dynamic braking current and obtained by the Joule heat calculation unit in the dynamic braking period, and a sum of the Joule heat resulting from the arc and the Joule heat resulting from the dynamic braking current, every time dynamic braking is performed; and a comparison unit which compares an integration value obtained by the integration unit with a preset reference value and outputs a comparison result.