Stepper Motor And Stepper Motor Drive Common Problem Summary

- Sep 12, 2017-

Stepper motor and stepper motor drive common problem summary

ONE.What is a  stepping motor? Under what circumstances use stepper motor?

A stepper motor is an actuator that converts electrical pulses into angular displacements. It is popular to say, when the stepper driver receives a pulse signal, it drives the stepper motor to rotate a fixed angle (ie, the stepping angle) in the set direction.You can control the number of pulses to control the angular displacement, so as to achieve accurate positioning; At the same time you can control the pulse frequency to control the motor speed and acceleration, so to get speed control. So when need accurate positioning or speed control,can consider to use stepper motor many kinds of stepper motor? What's the difference?

Stepper motor is divided into three kinds: permanent magnet (PM), reactive (VR) and hybrid (HB)

Permanent magnet step is generally two-phase, torque and volume is small, the step angle is generally 7.5 degrees or 15 degrees;

Reaction step is generally three-phase, can achieve large torque output, step angle is generally 1.5 degrees, but the noise

and vibration are great. This kind of motor in Europe and the United States and other developed countries have been eliminated

at 80 years;

Hybrid stepper is the combination advangtages of permanent magnet and the reaction, it is divided into two-phase, 

four-phase and five-phase: two-phase stepping angle is generally 1.8 degrees and five-phase stepping angle is generally 

0.72 degrees. This stepper motor is the most widely used.And ECON stepper drive is for this kind of stepper motor too.

THREE.What is the holding torque?

HOLDING TORQUE refers to the stepper motor power is turned on, but no rotation, the stator lock rotor torque.

It is one of the most important parameters of the stepper motor, and the torque of the stepper motor at low speed is usually 

close to the holding torque. The greater the torque is, the stronger the load capacity of the motor. As the output torque of the stepper motor decreases with increasing speed, the output power also changes with the speed, so holding torque becomes one of the important parameters to measure the stepper motor. For example, when people say that the 2N.M stepper motor, in the absence of special instructions is the holding torque of 2N.M stepper motor.Shenzhen ECON Technology has 2Nm hybrid stepper motor,and 2Nm hybrid servo motor(easy servo motor). many driving mode of stepper motor?

In general, the stepper motor has constant voltage, constant current driving, constant voltage drive has been nearly eliminated, the current widespread use of constant current drive. much accuracy for stepper motor? Is it cumulative?

The precision of the stepper motor is 3-5% of the stepping angle. Stepping motor single step deviation does not affect the accuracy of the next step, so the stepper motor accuracy is not accumulated.

SIX.The MAX surface temperature of stepper motor

Too high temperature will make the motor magnetic material demagnetization, resulting in decreased torque or even lost. Therefore, the maximum allowable temperature of the motor surface should depend on the demagnetizing point of the different motor magnetic materials. Generally speaking, the demagnetizing point of the magnetic material is more than 130 degrees Celsius, so the stepper motor surface temperature is normal at 80-90 degrees Celsius.

SEVEN.why stepper motor torque will decrease with the speed rise?

When the stepping motor rotates, the inductance of each phase winding of the motor will form a reverse electromotive force;the higher frequency, the greater the reverse electromotive force.Under this reaction, the motor with the frequency (or speed)increases and phase current decreases, resulting in decreased torque.

EIGHT.why stepper motor can run normally at low speed,if higher than a certain speed,can not start, and accompanied by howling?

Stepper motor has a technical parameter: no-load start frequency, that it is, stepper motor in the case of no-load can start the normal pulse frequency, if the pulse frequency is higher than the value,the motor can not start normally, may occur step lost or stall. In the case of load, the start frequency should be lower. If want to make the motor to achieve high-speed rotation, the pulse frequency should have accelerated process, that it is, the start frequency is low, and then according to a certain acceleration to the desired high frequency (motor speed from low speed to high speed). We recommend that the no-load start frequency select twice of per lap motor rotatation pulses counts. to overcome vibration and noise of two-phase hybrid stepper motor in the low-speed operation?

Stepper motor low-speed rotation vibration and noise is its inherent shortcomings, generally can take below methods to overcome:

A,stepper motor work in the resonance zone, can be achieved by changing the gear ratio to improve the stepper motor running speed.

B,use stepper drive with micro-step function, which is the most commonly used,easiest way. Because the micro-step drive 

motor phase current flow than half-step gentle.

C,take a step angle smaller stepper motor, such as three-phase or five-phase stepper motor, or two-phase micro-step stepper motor.

D, replaced by DC or AC servo motor, can almost overcome the vibration and noise, but cost is higher.

E,add magnetic damper in the motor shaft,market has this product, but mechanical structure changes larger.

TEN.The subdivision of micro-step driver can represent the accuracy?

Stepping motor subdivision technology is essentially an electronic damping technique (please refer to the literature), the main purpose is to reduce or eliminate the low-frequency vibration, improving stepper motor operating accuracy is only a sub-function. For example, for a two-phase hybrid stepping motor with a step angle of 1.8 degrees,if the subdivision of the micro-step drive set to 4, then the motor's operating resolution is 0.45 degrees per pulse, and the accuracy of the motor can be reached or close 0.45 degrees,depends on the micro-step drive subdivision current control accuracy and other factors. Different manufacturers of micro-step drive accuracy may vary widely; the greater subdivision, more difficult to control precision.

ELEVEN.the difference between serial connection and parallel connection of four-phase drive-type stepper motor and stepper drive

Four-phase hybrid stepping motor is generally driven by two-phase stepper drive, so the connection can be serial or parallel make four-phase motor connected into two-phase. Series connection is generally used in the case of motor low speed. At this time,require drive output current is 0.7 times of motor phase current,then motor heat is small; parallel connection method is generally used in the case of high speed (also known as high-speed connection),require drive output current is 1.4 times of motor phase current,so motor heat is serious. to determine the stepper motor drive DC power supply?

A,power supply voltage 

The power supply voltage of the hybrid stepper motor driver is a wide range (for example, the supply voltage of the TD542 is 24-50VDC). The supply voltage is usually selected based on the operating speed and response requirements of the motor. If the motor is operating at high speed or quick response, the voltage is high, but care that the ripple of the supply voltage can not exceed the maximum input voltage of the driver. Otherwise, the drive may be damaged. If the motor operating speed is low, you can consider to select lower value of voltage.

B,power supply output current

The power supply current is generally determined by the output phase current I of the driver. If use linear power supply,the current take 1.1-1.3 times of I;if use switching power supply,current is 1.5-2.0 times of I.If a power supply provide power to several drives at the same time, consider to double the current.

THIRTEEN.hybrid stepper motor driver enable signal use under what circumstances?

When the enable signal Ena is low,the current output from the driver to the motor is cut off and the motor rotor is in a free state (offline). In some automation equipments,if the drive in the case of continuous power requirements can be used to manually rotate the motor shaft, you can set low Ena value,make motor off-line, manual operation or adjustment. After completed,the Ena signal set high to continue the automatic control. to use a simple way to adjust the two-phase stepper motor rotation direction when motor is in power?

Simply swap the A+/A- connection of motor& drive (or B + and B-).

FIFTEEN.explain the meaning of IP as follows:

IP (INTERNATIONAL PROTECTION) protection system is drafted by IEC (INTERNATIONAL ELECTROTECHNICAL COMMISSION). The electrical appliances in accordance with its anti-dust and anti-moisture characteristics to be graded. Here refers to the foreign objects with tools, human fingers, etc. are not exposed to the electrical part of the electricity, so as not to electric shock. IP protection level is composed of two figures, the first number represents electrical dust,prevent the intrusion of foreign objects,

the second number means electrical anti-moisture, waterproof intrusion of the degree of closure, Lou larger the degree of protection higher.

SIXTEEN.What is the motor insulation rating?

Indicates the insulation material used for the motor and the insulation structure, allowing the maximum working temperature

. Motor insulation structure heat resistant clase is divided into 5, as shown in below picture:


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