A braking circuit for braking an electric motor having an armature and run and brake windings, which includes a switching circuit disposed between a source of electrical power and the run winding, this circuit being operable to disconnect the run winding from the source of electrical power. The braking circuit further includes a switching mechanism operable to connect the brake winding in order to brake the electric motor. The switching mechanism preferably connects the brake winding after a predetermined period of time has elapsed from the disconnection of the run winding. This braking circuit can be used in a saw for braking the saw's blade.

Apparatus and method for braking electric motors

A method and apparatus for controlling, in power failure, such a machine that a workpiece and a tool are required to be always synchronized in their motion. The method and apparatus allow the tool and workpiece to move back and stop at a safe area without causing any damage to them when the main power source is lost. When a power failure has happened in the middle of a synchronous operation of the motors (S1), a power regeneration function is first disabled (S2). Then a braking control command is issued so as to decelerate the tool drive motor and the workpiece drive motor while maintaining their synchronization (S3). In this step S3, the deceleration rate is controlled so that the motors regenerates energy just enough for driving the tool feed motor. The tool retracts back to an area where it is no longer engaged with the workpiece, by driving the tool feed motor with the regenerative energy produced by the deceleration of the tool drive motor and the workpiece drive motor (S4).

Method and apparatus for control in power failure

A locomotive traction motor control system includes a traction motor to propel a locomotive when it motors, and to slow the locomotive when it engages dynamic braking. A resistive element dissipates electrical energy generated during dynamic braking. A control element, operatively coupled to the resistive element, selectively isolates the resistive element from the tractor motor when the locomotive motors. The resistive grid isolation may be accomplished with a pair of isolation switches coupled in series between the traction motor and the resistive element and a controller which opens the isolation switches when the locomotive motors and closes the isolation switches when the locomotive engages dynamic braking.

Braking grid isolation for locomotive traction motor control system

An improved electrical circuit configuration for a chopper circuit is disclosed which is particularly adapted for use with an inductive load such as a braking resistor of the type used in many rapid transit vehicles Instead of connecting a di/dt reactor directly in series with the electronic switch of the chopper circuit, a di/dt reactor is connected in series with the freewheeling diode Using this configuration, the di/dt reactor does not have to continuously handle the average current through the electronic switch during the entire chopping operation Hence, a much smaller, lighter, and less expensive di/dt reactor can be utilized

Chopper circuit for dynamic braking in an electric power conversion system

A retarding system for an electric drive machine ( 100 ) includes a direct current (DC) link ( 312 ), at which a DC voltage is developed, disposed between a rectifier ( 206 ) and an inverter ( 208 ). A first contactor switch ( 216 ) electrically communicates with a first rail of the DC link ( 312 ), and a second contactor switch ( 216 ) electrically communicates with a second rail of the DC link ( 312 ). A first resistor grid ( 214 ) is connected in series between the first contactor switch ( 216 ) and the second contactor switch ( 216 ). The first resistor grid ( 214 ) dissipates electrical energy in the form of heat by conducting a current between the first rail and the second rail of the DC link ( 312 ) when the first contactor switch ( 216 ) and the second contactor switch ( 216 ) are closed.

Electric drive retarding system and method

A control circuit which permits a direct current motor to operate during traction or during braking in such a manner that energy can be either dissipated or recovered; and, in particular, the invention embodies gradual, continuous, and reversible shifting from one form of braking action to another.

Control circuit for operating a direct current motor during traction or braking

not available for EP0051518Abstract of corresponding document: US4555652A control circuit which permits a direct current motor to operate during traction or during braking in such a manner that energy can be either dissipated or recovered; and, in particular, the invention embodies gradual, continuous, and reversible shifting from one form of braking action to another.

Brulard Michel Charles

Papers

Control circuit for operating a direct current motor during traction or braking

Control circuit for drive or/and brake operation of a dc motor

Traction motor control