Discharge circuit and discharging method of motor drive power supply circuit, and robot controller

A robot controller configured to control an industrial robot comprising a motor in each axis, the robot controller comprising:

• a power supply circuit comprising a rectifying circuit and a smoothing capacitor, the power supply circuit outputting DC power from a secondary side based on AC power supplied to a primary side;
• a first voltage detector which detects an AC voltage inputted to the primary side of the power supply circuit;
• a second voltage detector which detects a voltage on the secondary side of the power supply circuit;
• a discharge resistance provided in parallel with the power supply circuit on the secondary side;
• a switching element configured to make a current flow or not flow through the discharge resistance;
• a servo controller to which the DC power outputted from the secondary side is supplied to drive and control the motor;
• a main control means configured to control the motor by outputting a command to the servo controller;
• and
• a power supply control means configured to perform a discharge control by controlling the switching element to allow an electric current to flow through the discharge resistance, so as to reduce the voltage on the secondary side of the power supply circuit;
• wherein the power supply control means is configured to perform:
• the discharge control when a voltage detected by the second voltage detector exceeds a regenerative determination value;
• and
• the discharge control after a time period required for a stop operation of the industrial robot has elapsed, when the voltage inputted to the primary side of the power supply circuit drops below a power failure determination value;
• and
• wherein the main control means performs processing of making a deceleration stop of the industrial robot when the voltage inputted to the primary side of the power supply circuit drops below the power failure determination value.