The difference between linear motors, servo motors and stepper motors

Linear motors. It is also a servo motor.

one. Theoretically, any system with feedback (usually Hall or raster feedback) should be a servo system.

Therefore, servo motors are generally divided into rotary servo motors and linear motors. This is the difference between a linear motor and a servo motor. The differences between linear motors and servo motors are as follows:

Servo motor refers to the engine that controls the operation of mechanical parts in the servo system, and is an indirect transmission device that complements the motor. The servo motor can accurately control the speed and position, and can convert the voltage signal into torque and speed to drive the controlled object, with closed-loop control. A linear motor is a type of mechanical energy that directly converts electrical energy into linear motion energy.

does not require any intermediate conversion mechanism. It can be seen as a rotating electrical machine, cut radially into a plane. The side that evolves from the stator is called primary, and the side that evolves from the rotor is called secondary.

In practice, the primary and secondary are made of different lengths to ensure the coupling between the primary and secondary stages.

remains unchanged within the required travel range; Linear motors can be short primary and long secondary, or long primary and short secondary. Considering the manufacturing cost and operating cost, the short primary and long secondary are generally used at present. Linear motors have compact structure, low power consumption, fast movement speed and acceleration.

Advantages of large and fast speed (Linear motors can achieve high-precision position control in different ranges from high speed to low speed by directly driving the load.) Motors are prone to low-frequency vibrations at low speeds, and the vibration frequency is related to the load and the performance of the drive. In general, the vibration frequency is half the frequency of the motor's no-load take-off.

This low-frequency vibration phenomenon is determined by the working principle of the servo motor, which is very unfavorable to the normal operation of the machine. When the servo motor works at low speed, damping technology should generally be used to overcome the phenomenon of low-frequency vibration, such as adding a damper to the motor or subdividing technology on the drive.

The pulse motor you are talking about should be a stepper motor, right? If it is a stepper motor, in fact, the stepper motor itself is also a type of servo motor. He is that each pulse corresponds to the corresponding step angle.

The speed of the motor is proportional to the frequency of the pulses, while the angle of rotation is proportional to the number of pulses. If you want to say that the difference is borrowed from a statement I have seen on the Internet, it is that what you are asking about is actually the difference between apples and fruits, because apples belong to fruits.

But it's just one of the many fruits, I don't say it, stepper motor is a servo motor of servo motor, including: stepper motor, DC servo motor, AC servo motor, linear motor and so on. So I'll give you the example above.

However, if you ask about the difference between a stepper motor and an AC servo or DC servo, I can tell you the following: the stepper motor needs a slow acceleration to start, and it can only be controlled by pulse, and the torque of the motor is inversely proportional to the speed, the higher the speed, the smaller the torque, and the maximum speed will not exceed 1500r, and he has no feedback device, the speed is high and easy to lose steps, and the speed is low and easy to shake. Other motors have position (pulse control) and speed (analog control) with feedback devices, the torque is constant at the rated speed, the speed can reach tens of thousands of revolutions, and because of the feedback device, there will be no loss of steps and other phenomena.

Positioning or residual moment:

The torque required to rotate the output of the motor when no current is passing through the windings.

Driver: An electrical control device used to run a stepper motor. This includes a power supply, a logic programmer, a switching element, and a variable frequency pulse source that determines the step rate.

Dynamic torque: The torque generated by the motor at a certain step rate. The dynamic moment can be pulled by pulling

In (pull) moment or pull

out torque.

Holding torque: The torque required to rotate the motor on the output shaft when the winding is turned on a steady-state direct current.

Inertia: The inertial measurement of an object's acceleration or deceleration. It is used here to refer to the inertia of the load that the motor is going to move, or the inertia of the rotor of the motor.

Linear step increment (or step size):

The linear displacement of the lead screw per step angle of the rotor.

Maximum temperature rise: The motor is designed to allow the temperature rise. The temperature rise of a motor is an inherent property of the electric energy loss and temperature increase of the motor when it is energized.

The main types of electrical energy losses are resistance heat loss (copper loss), iron loss and friction loss. The temperature of the motor is the sum of the total loss, heating temperature, and ambient temperature.

Pulse Rate: The number of pulses (pps) applied to the windings of the motor per second. The pulse rate is equal to the motor step rate.

Pulses per second (pps):

The number of steps produced by the motor in one second (sometimes referred to as "step seconds"). This is determined by the frequency of the pulses generated by the motor drive.

Lifting speed: A drive technology that increases a given load from the original low step rate to the maximum, and then decreases it back to the original rate without losing the motor step.

Single-step response:

The motor carries out a complete step in the required time.

Step: The angle at which the rotor rotates each time the motor receives a pulse, for linear motors, the step is the straight-line distance.

Step angle: The rotation produced by the rotor at each step, measured in degrees.

Weekly Spin Steps:

The rotor rotates 360°The total number of steps required. The sum of the drag moment and the moment of inertia.

Moment: The sum of the drag moment and the moment of inertia.

pullout torque:

The maximum torque that a motor can produce at a constant speed. Because the velocity is constant, there is no moment of inertia either. The kinetic energy and inertial load inside the rotor increase the pull-out torque.

pullin torque:

The center must overcome the acceleration torque of the rotor inertia, as well as the fixed connected external load and various frictional torques during acceleration. Therefore, the pull-in moment is usually less than the pull-out moment.

Moment to inertia ratio:

The holding moment is divided by the rotor moment of inertia.

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

1. Working principle.

A stepper motor is an open-loop control element stepper motor device that converts an electrical pulse signal into angular displacement or linear displacement, see how a stepper motor works.

The servo mainly relies on pulses to position, and the servo motor itself has the function of sending out pulses, so every time the servo motor rotates an angle, it will send out a corresponding number of pulses.

2. Control accuracy.

The accuracy of the stepper motor is generally achieved through the precise control of the step angle, and the step angle has a variety of different subdivision gears, which can be accurately controlled.

The control accuracy of the servo motor is guaranteed by the rotary encoder at the rear end of the motor shaft, and the control accuracy of the general servo motor is higher than that of the stepper motor.

3. Speed and overload capacity.

The stepper motor is prone to low-frequency vibration when running at low speed, so when the stepper motor is working at low speed, it is usually necessary to use damping technology to overcome the low-frequency vibration phenomenon.

Servo motors do not have this phenomenon, and their closed-loop control characteristics determine that they maintain excellent performance at high speeds.

Precautions when installing stepper and servo motors:

1. When installing or disassembling the coupling parts, do not use the hammer to directly hit the shaft end. Because the hammer strikes directly on the shaft end, the encoder at the other end of the stepper servo motor shaft is broken.

2. Be sure to do your best to align the shaft end to the best state, because bad alignment may lead to vibration or bearing damage.

Difference Between Stepper Motor and Servo Motor:

1. The way of control is different.

The servo motor is mainly composed of three parts, namely the motor body, the driver and the encoder. In comparison, stepper motors have one less encoder.

The movement of the servo motor is a closed-loop motion. Because there is no encoder structure, no one knows what kind of work the stepper motor receives the instruction signal, so the control accuracy cannot be guaranteed.

2. The workflow is different.

Stepper motor: The workflow generally requires two pulses for the stepper motor to work, the signal pulse and the direction pulse.

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

3. The low-frequency characteristics are different.

Stepper 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 torque is different.

The torque of the servo motor is very stable, and the torque does not change much whether it is moving at low speed or high speed. Comparatively speaking, the stepper motor is not so calm, its original movement speed is relatively low, if the speed is forcibly accelerated, the motor will lose a lot of torque, it is difficult to meet the actual needs.

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.

Main differences: 1. The stepper motor is an open-loop control mode, and the servo motor is a closed-loop control;

2. The stepper motor is an error-free control system, and the servo motor is an error control system;

3. There is no zero jitter in the stepper motor, and there is zero jitter in the servo motor;

4. The stepper motor has the characteristics of torque frequency, and the servo motor can output constant torque at the rated revolution;

5. The stepper motor is relatively low, and the servo motor is more expensive;

6. According to the application requirements, the parameters are selected appropriately, which can stably meet the application requirements.

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.

Hello, dear, I am glad to answer for you: the difference between stepper motor and servo motor Answer: good afternoon, dear kiss<>, the difference between stepper motor and servo motor: difference 1: Different ways of control The stepper motor controls the rotation angle by controlling the number of pulses, and a pulse corresponds to a step angle.

The servo motor controls the angle of rotation by controlling the length of the pulse time. Difference 2: The required working equipment and work process are different The power supply required by the stepper motor (the required voltage is given by the driver parameters), a pulse generator (now most of them are used plates), a stepper motor, a driver (the driver sets the step angle angle, such as setting the step angle as, at this time, give a pulse, the motor goes; The workflow is that the stepper motor generally requires two pulses:

Signal pulses and directional pulses. The power supply required for the servo motor is a switch (relay switch or relay board), a servo motor; The workflow is to connect a power supply switch and then a servo motor. Difference 3:

Different low-frequency characteristics Stepper motors are prone to low-frequency vibration at low speeds. The vibration frequency is related to the load situation and the performance of the drive, and it is generally considered that the vibration frequency is half of the no-load take-off frequency of the motor. This low-frequency vibration phenomenon, which is determined by the working principle of the stepper motor, is very detrimental to the normal operation of the machine.

When the stepper motor works at low speed, damping technology should generally be used to overcome the low-frequency vibration phenomenon, such as adding a damper to the motor, or using subdivision technology on the driver. The AC servo motor runs very smoothly and does not vibrate even at low speeds. The AC servo system has a resonance suppression function to cover the lack of rigidity of the machine, and the system has a frequency analysis function (FFT) inside the system, which can detect the resonance point of the machine and facilitate system adjustment.

Difference 4: The output torque of the stepper motor decreases with the increase of speed, and will drop sharply at higher speed, so its maximum working speed is generally 300 600r min. The AC servo motor has a constant torque output, that is, it can output the rated torque within its rated speed (generally 2000 or 3000 r min), and it is a constant power output above the rated speed.

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