What is the principle of stepper motor What is the difference between stepper motor and servo motor

Stepper motors and servo motors are precision motors driven by pulsed power circuits! The pulses control the stepping and rotation angle of the motor! Here's what they all have in common!

The difference is that the motor of the servo motor has its own pulse feedback circuit! Through timely signal feedback, the output correction is made by the drive circuit! Therefore, the accuracy of the servo motor is higher! It is mostly used in aerospace, military industry, scientific research and other precision instruments!

How it works. Usually the rotor of a motor is a permanent magnet, and when an electric current flows through the stator windings, the stator windings generate a vector magnetic field. This magnetic field causes the rotor to rotate by an angle so that the direction of the pair of magnetic fields of the rotor coincides with the direction of the magnetic field of the stator.

When the vector magnetic field of the stator rotates by an angle. The rotor also rotates at an angle with this magnetic field. With each input electrical impulse, the motor rotates an angle to take a step forward.

The angular displacement of its output is proportional to the number of pulses input, and the rotational speed is proportional to the pulse frequency. Change the order in which the windings are energized, and the motor will be reversed. Therefore, the rotation of the stepper motor can be controlled by controlling the number of pulses, the frequency and the energizing sequence of each phase winding of the motor.

Strictly speaking, the motor is powered by the electric magnetic field, which structure is similar, but the stepping can be achieved through the structure of the motor positioning, the power is relatively small, open loop, servo is a closed-loop synchronous motor, high precision, expensive.

The stepper motor is a digital motor, invented in order to achieve precise control, and can achieve high control accuracy in open-loop mode, so the cost of the stepper motor controller is not high, which is incomparable with other servo motors. The efficiency of stepper motors is generally not high, not as high as other servo motors, it is to sacrifice efficiency to improve control accuracy. For the specific working principle, you can refer to the book "Controlling Motors".

That's a good point!!

Difference between stepper and servo:1The control accuracy is different, and the accuracy of the servo is high.

2.The characteristics of the low frequency are different, and the step is prone to vibration at low speeds. 3.

The saw frequency characteristics are different, and the servo is a constant torque. 4. The overload capacity is different, and the stepping generally does not have the overload capacity. 5.

The running performance is different, and the stepping is open-loop, which is prone to step loss. 6.Speed response performance is different.

Take a look at the book "Stepper Motor Application Technology", it's pretty good.

1. Different control methods: the stepper motor controls the rotation angle by controlling the number of pulses, and the servo motor controls the rotation angle by controlling the length of the pulse time; 2. The process is different: the stepper motor generally needs two pulses to work, and the servo motor is a power supply connection switch, and then connected to the servo motor; 3. Different characteristics:

The stepper motor is prone to low-frequency vibration at low speed, while the servo motor runs very smoothly; 4. The speed is different: the maximum working speed of the stepper motor is 300 600r min, and the rated speed of the servo motor is 2000 or 3000r min.

Stepper motors. The stepper motor, also known as the pulse motor, is based on the most basic electromagnetic principle of electromagnetism, which is an electromagnet that can rotate freely, and its action principle is to rely on the change of air gap magnetic conductance to generate electromagnetic torque. Stool limb yard.

There are many structural forms and classification methods of stepper motors, which are generally divided into three types: reluctance, permanent magnet and mixed magnet according to the excitation mode; According to the number of phases, it can be divided into single-phase, two-phase, three-phase and multi-phase forms.

Among the stepper motors used in China, the reactive stepper motor is the main one. The operation performance of the stepper motor is closely related to the control mode, and the stepper motor control system can be divided into the following three categories from the perspective of its control mode: open-loop control hunger cultivation system, closed-loop control system, and semi-closed-loop control system.

Semi-closed-loop control systems are generally classified as open-loop or closed-loop systems in practical applications.

The difference between stepper motor Sakuraeda Zhenghe servo motor:

The way of control is different:The stepper motor controls the rotation angle by controlling the number of pulses, and the servo motor controls the rotation angle by controlling the length of the pulse time.

The workflow is different:The stepper motor needs two pulses to work, and the servo motor is the power connection switch; The characteristics of low tie positive frequency are different: the stepper motor is prone to low-frequency vibration at low speed, and the servo motor runs very smoothly.

The differences between stepper motor and servo motor are as follows:

1.The accuracy of a stepper motor is superior to that of a servo motor because it does not accumulate errors and is usually only required to do open-loop control, but the servo motor is superior to the stepper motor in terms of responsiveness.

2.The stepper motor is prone to low-frequency vibration at low speed, and when it works at low speed, damping technology or subdivision technology is generally used to overcome low-frequency vibration, while the servo motor runs very smoothly, and there will be no vibration even at low speed.

3.It takes hundreds of milliseconds for the stepper motor to accelerate from a standstill to the working speed, while the acceleration performance of the AC servo system is better, generally only a few milliseconds, and can be used for control occasions that require fast start and stop.

4.The stepper motor generally does not appear to lose steps, which is convenient to control, and the servo motor, especially the low-end servo motor, is not precise in speed, and it is not easy to control and operate.

5.Stepper motors do not have the ability to overload, whereas servo motors have a strong overload capacity.

The characteristics of the motor itself are quite different, and it can be applied to occasions with different motion requirements. But the control is the same for the user.

1. Different ways of controlStepper motor: The rotation angle is controlled by controlling the number of pulses, and one pulse corresponds to a step angle.

Servo motor: The angle of rotation is controlled by controlling the length of the pulse time.

2. The workflow is differentStepper Motors: The workflow generally requires two pulses for stepper motors to work: signal pulses and direction pulses.

Servo motor: The workflow is a power connection switch, and then a servo motor.

3. The low-frequency characteristics are differentStepper motor: It is easy to have low-frequency vibration at low speed.

Servo motor: It runs very smoothly and does not vibrate even at low speeds.

4. The characteristics of moment frequency are differentStepper motor: The output torque decreases with the increase of speed, and will drop sharply at higher speed, so its maximum working speed is generally 300 600r min.

Servo motor: it is a constant torque output, that is, within its rated speed (generally 2000 or 3000 r min), the output of rated torque, and above the rated speed is constant power output.

The main aspects are as follows:

1. The torque frequency characteristics are different: the output torque of the stepper motor will decrease rapidly as the speed of the motor increases, while the servo can maintain a constant torque output within the rated speed;

2. Different control methods: stepper motors generally adopt position open-loop control, only current closed-loop control, and servo can adopt position loop + speed loop + current loop three-loop closed-loop control;

3. Parameter configuration and debugging: there is basically no parameter debugging process for stepper motors, and the installation can be used; The servo needs to set parameters according to factors such as load inertia and load rigidity, and the process is more troublesome and requires certain application experience;

4. Control accuracy: The control accuracy of the stepper motor is basically defined by the step angle of the motor, for example, the step angle of the 2-phase hybrid stepper motor is, and its machining accuracy does not exceed; The accuracy of the servo is mainly determined by the accuracy of the encoder;

5. Scope of application: The application scenarios of stepper motors are mostly used within 600rpm; Servo motors can be applied to the rated speed of the motor, such as 2000 to 3000rpm;

6. Cost: The overall application cost of stepper motor is relatively low, and the cost of the motor of the same specification is only 1 3 of servo motor

On the whole, stepper motors have great advantages in low-speed applications.

The differences between stepper motor and servo motor are as follows:

1. The characteristics of moment frequency are different; The output torque of the stepper motor will decrease with the increase of speed, and the servo motor is a constant torque output.

2. The overload capacity is different; Stepper motors generally do not have overload capacity, while servo motors have strong overload capacity.

3. The speed response performance is different; It takes hundreds of milliseconds for the stepper motor to accelerate from a standstill to the working speed, while the acceleration performance of the servo system is better, generally only a few milliseconds, which can be used for control occasions that require fast start and stop.

4. The low-frequency characteristics are different; The stepper motor is prone to low-frequency vibration at low speed, when it works at low speed, damping technology or subdivision technology is generally used to overcome low-frequency vibration, and the servo motor runs very smoothly, and there will be no vibration even at low speed.

5. The running performance is different; The control of the stepper motor is open-loop control, and the starting frequency is too high or the load is too large, and it is easy to lose steps or stall rotors, and the speed is too high when stopping.

The AC servo drive system is closed-loop control, the driver can directly sample the feedback signal of the motor encoder, and the internal position loop and speed loop are formed, and there will generally be no step loss or overshoot of the stepper motor, and the control performance is more reliable.