Method for controlling an inverter for driving a swing motor

摘要

The present disclosure relates to a method of controlling an inverter for driving a swing motor, and particularly, maximally generates braking torque of the swing motor upon generation of failure of the inverter by switching on/off a lower-phase switch or an upper-phase switch of the inverter in order to prevent an upper swing body from freely rotating which is generated when a semiconductor switch of the inverter is switched off upon the generation of over-current and over-voltage of the inverter that drives the swing motor, thereby being capable of protecting the inverter, rapidly stopping the upper swing body, and preventing the risk of accidents.

主权项

1. A method of controlling an inverter for driving a swing motor so as to swing an upper body of a hybrid excavator, the method comprising:
confirming whether failure caused by over-current and over-voltage is generated in the inverter for driving the swing motor; when the failure of the inverter for driving the swing motor is confirmed, switching off an upper-phase switch or a lower-phase switch of the inverter for driving the swing motor; detecting a DC link voltage connected with the inverter for driving the swing motor and a motor speed of the swing motor; calculating an on/off duty ratio of the upper-phase switch or the lower-phase switch at which maximum braking torque is generated using the detected DC link voltage and the detected motor speed; switching on/off the upper-phase switch or the lower-phase switch of the inverter for driving the swing motor according to the calculated on/off duty ratio so as to generate braking torque of the swing motor; generating the braking torque in the swing motor to rapidly stop the upper body of the hybrid excavator; checking whether the motor speed is decelerated to a predetermined speed or lower, wherein the predetermined speed is a speed at which the swing motor may stop by a separately provided mechanical brake without failure; wherein when the DC link voltage and the motor speed are changed by the braking torque after the switching, further comprising renewing the calculated on/off duty ratio according to the changed DC link voltage and motor speed, wherein the switching comprises switching on/off the upper-phase switch or the lower-phase switch according to the renewed on/off duty ratio; and wherein the on/off duty ratio is in proportion to the detected DC link voltage and is in inverse proportion to the detected motor speed.