DC motor speed instability, usually caused by the following two aspects of the original, can choose to deal with the approach.
(1) The power supply voltage is not resolute or the parameters of the control system are not properly adjusted, so that the speed of the motor is sometimes fast and sometimes slow, and even lead to motor vibration in severe cases. The way to deal with is: pay attention to check the armature circuit, the excitation circuit of the power supply voltage has not changed, if the power supply voltage is not resolute, should be the first to clean up the power supply defects. The power supply voltage is not resolute often with the speed control system parameters are not properly adjusted, should be based on the detailed conditions, the parameters will be adjusted.
(2) The internal defects of the motor, such as the brush against the base line orientation, series excitation winding, reversing the polarity of the commutator winding, so that the motor load changes, constituting the speed is not resolute. Treatment is: pay attention to check the neutral line orientation of the calibration brush, check the polarity of the connection line of each winding is not accurate. Together with the query brush under the spark, armature current has no significant changes, in order to analyze the differences between the defective elements.