MOTOR BRAKE COMMAND WITH MOTOR PULSE-WIDTH MODULATION
Publication Date: 2014-Mar-28
The IP.com Prior Art Database
The invention proposes a technique to control brake on a transmission. Brake is supplied by pulse-width modulation (PWM) of the motor. The motor current is rectified with two simple diodes. Timing of brake control is managed by the PWM before and after motion curve. The brake is supplied without hardware (HW) modification when a motor drive board is available without brake output.
FIELD OF INVENTION
The invention generally relates to an electric motor and more particularly to an electric motor brake.
BACKGROUND OF THE INVENTION
Generally, electric motor brake includes an electromagnetic brake coil. Electromagnetic brake coil is energized to actuate electric motor brake. The electric motor brake is actuated to a released condition permitting rotation of an electric motor. The electromagnetic brake coil is de-energized for actuating electric motor brake to a braking condition. A separate relay for the electromagnetic brake coil in addition to a motor starter is required to stop rotation of the motor and de-energization thereof.
A conventional technique relates to a motor brake control system. The motor brake control system is used on a motor having a motor brake retarder. A throttle fuel control is used to respond to manual selection for sequentially retarding selected cylinders in the electric motor. A transducer for sensing a speed of the electric motor is provided. The transducer generates a series of output pulses which access high revolutions per minute (RPM) detector and a low RPM detector. When the electric motor exceeds a predetermined high RPM value, the motor brake control system activates all retarders to apply brake to the electric motor. The brake retarders are released when the brake retarders are on and the electric motor drops below a predetermined low RPM value. An emergency override is provided to manually activate the brake retarders.
Another conventional technique relates to a motor brake control circuit. The motor brake control circuit is provided with a coil short circuit for short-circuiting power terminals of a coil. The power terminals of the coil are short-circuited once a brake signal is issued from brake circuit. The brake is forcibly and continuously applied to the motor.
Time required for motor to come to a complete stop after an issuance of brake signal is reduced. The motor is not affected by external force such as vibration to shift rotary position of the motor in the braked condition.