Electronic stable speed motor application circuit

Electronic stable speed motor application circuit

The electronic speed stabilization method realizes the steady speed control of the motor through the automatic control function of the motor power supply circuit. The figure shows an
application circuit . As shown in Figure (b), the DC motor is connected in the circuit as part of the circuit. Since the coil winding of the DC motor
has a certain impedance, the circuit is connected in a new way. Therefore, the resistors RI, Rz, and R3 are selected so that rIJRI=R:Z/R3, which is a balanced state.
Since the rotor coil will generate a reverse electromotive force when it rotates, and the effect of the directional electromotive force will cause the internal resistance rm of the motor to change with the motor speed,
a potential difference will be generated between a and b that is proportional to the motor speed. That is to say, when the motor speed increases, the reverse electromotive force becomes larger, and
the potential of point a relative to point b becomes higher. Therefore, the emitter voltage of transistor VT2 increases, the base current of VT2 decreases, and the collector current of VI2 also
decreases. The collector current of VT2 is the base current of the VT1 transistor, which will also reduce the collector current of VT1 . As a result,
the voltage supplying the motor drops and the motor 's speed automatically decreases.