Second, energy consumption braking: A direct current is […]
Second, energy consumption braking:
A direct current is applied to the stator windings to produce a fixed magnetic field. At this time, the rotor cuts the magnetic lines of force in the direction of rotation, thereby generating a braking torque. Since the braking method is not like the regenerative braking, the energy generated during the braking is fed back to the grid, but the motor alone consumes the kinetic energy, so it is called the energy braking. In addition, since the stator winding is driven by direct current, the energy consumption braking is also called DC injection braking. As shown in the figure below, the reverse point switch switch Q is used to reverse the point voltage to the grid. At this time, the armature current will become duplicated, and the current magnitude is equivalent, which will result in a large braking property of the motor torque. Stopped.
The energy consumption braking relies solely on the motor to consume kinetic energy to achieve the purpose of stopping, so the braking effect and accuracy are not ideal. This braking method is generally not used in applications where braking time is short and braking is good. Such as lifting machinery, its operating characteristics are low motor speed, frequent start, stop and forward and reverse, and drag the heavy objects to run.
In order to achieve accurate and flexible control, the motor is often in a braking state and requires a large braking torque. The energy consumption brake does not meet the above requirements. Therefore, the lifting machinery generally adopts reverse braking and requires mechanical braking to prevent the heavy objects from slipping during operation or loss of power.