The difference between DC motor and stepper motor

Stepper motors are actually a special DC brushless motor that requires DC drive and driver commutation. However, because the motion characteristics are quite different from DC brushless motors, stepper motors are divided into a separate product category. DC motors are divided into DC brushed motors and DC brushless motors. Generally speaking, DC motors generally refer to DC brushed motors. The brushed DC motor will turn as long as the appropriate voltage is applied, and the number of turns is difficult to control precisely; while the stepper motor works according to the beat and can rotate at a very small angle, and the control methods are also different.

1. Stepping motor

1. The stepper motor can realize the precise control of the motor speed and position. Generally, the accuracy of the stepper motor is within 5% of the step angle, and no error is accumulated.

2. The stepping motor must be driven before it can run. The driving signal must be a pulse signal. When there is no pulse, the stepping motor is stationary. If an appropriate pulse signal is added, it will rotate at a certain angle (called the step angle). . The speed of rotation is proportional to the frequency of the pulses.

3. Changing the sequence of pulses can easily change the direction of rotation. Therefore, equipment such as printers, plotters, and robots use stepping motors as the power core.

4. The maximum temperature allowed on the surface of the stepping motor. Excessive temperature of the stepping motor will first demagnetize the magnetic material of the motor, resulting in a decrease in torque and even out of step. Therefore, the maximum temperature allowed on the surface of the motor should depend on the demagnetization point of different magnetic materials of the motor; generally speaking, the demagnetization of magnetic materials The points are all above 130 degrees Celsius, and some are even as high as 200 degrees Celsius, so the external temperature of the stepper motor is completely normal at 80-90 degrees Celsius.

5. The torque of the stepper motor will decrease with the increase of the speed. When the stepper motor rotates, the inductance of each phase winding of the motor will form a back electromotive force; the higher the frequency, the greater the back electromotive force. Under its action, the phase current of the motor decreases as the frequency (or speed) increases, resulting in a decrease in torque.

6. The stepper motor can run normally at low speed, but it cannot start when the speed is higher than a certain speed, and it will be accompanied by howling sound. The stepper motor has a technical parameter: no-load starting frequency, that is, the pulse frequency at which the stepper motor can start normally under no-load conditions. If the pulse frequency is higher than this value, the motor cannot start normally, and step loss or stalling may occur. Under load, the starting frequency should be lower. If you want to make the motor rotate at high speed, the pulse frequency should have an acceleration process, that is, the starting frequency is low, and then rise to the desired high frequency at a certain acceleration (the motor speed increases from low speed to high speed). With its remarkable characteristics, stepper motors play an important role in the era of digital manufacturing. With the development of different digital technologies and the improvement of stepper motor technology, stepper motors will be applied in more fields.

2. DC motor

A DC motor is a rotating electrical machine that converts DC electrical energy into mechanical energy (DC motor) or converts mechanical energy into DC electrical energy (DC generator). It is a motor that can convert DC electric energy and mechanical energy into each other. When it operates as a motor, it is a DC motor, which converts electrical energy into mechanical energy; when it operates as a generator, it is a DC generator, which converts mechanical energy into electrical energy. Including DC generators and DC motors. DC motors are divided into DC brushed motors and DC brushless motors. DC brushless motors require a driver to achieve electronic commutation, which is expensive but has a long life and low noise; DC brushed motors are low in cost and easy to use, but have a short life and high noise.