Analysis of the causes of faults in variable frequency braking motors at rated speed

The braking motor is a three-phase asynchronous motor with an added disc-type DC brake, consisting of a DC disc electromagnetic brake mechanism between the top cover and fan of a Y-series motor. Braking motors are very convenient for controlling the start and stop of operations and are widely used in various mechanical equipment and drivers that require quick stopping and accurate positioning, such as metalworking machine tools, packaging machinery, woodworking machinery, food machinery, chemical machinery, textile machinery, engineering machinery, and gear reducers.

A brake motor is a three-phase asynchronous motor with an additional disc DC brake, consisting of a DC disc electromagnetic brake motor located between the top cover and the fan of a Y-series motor. Using a brake motor is very convenient for controlling the start and stop of operations, and it is widely used in various mechanical equipment and drives that require quick stopping and precise positioning, such as metal processing machine tools, packaging machinery, woodworking machinery, food machinery, chemical machinery, textile machinery, engineering machinery, and gear reducers.

When some sudden accidents occur during machine operation, a brake motor can help us stop the machine in time, relatively reducing the severity of such accidents. Common brake motors generally have two operating principles: one is to energize the coil during motor operation to release the lock and allow the motor to run, and when the motor stops, the brake coil is cut off and automatically tightened; the other is when the motor stops, the winding applies strong magnetic braking through the current of the brake motor control circuit.

During the debugging process of a brake motor's frequency converter, if the motor speed is too high, exceeding its rated operating frequency, it may generate noise during operation. The main reasons for this are as follows:

1. Determine if there is a filter device in the brake motor.

The output of a soft starter contains many high-order harmonics rather than a sine wave. Under the action of high-order harmonics, the motor will heat up more severely and be accompanied by abnormal sounds. However, after adding a filter to the brake motor, the soft starter output becomes a sine wave, which greatly reduces abnormal noise and heating.

2. The speed of a general brake motor should not exceed 1.2 times its rated value.

For example, one of the technical standards for general Y-series brake motor products is that if the speed is increased to 1.2 times the rated value for more than 2 minutes under full motor load, harmful deformation will occur. The speed of a DC variable frequency special brake motor, being one to several times higher than the rated speed, can cause motor temperature rise due to excessively high frequency, leading to increased vibration, increased load on the bearings, and adverse effects on the motor's lifespan.

In fact, the