1.What is a stepper motor?
Stepper motor is an electrical pulse into the angular displacement of the actuator. Plainly speaking: When receiving a stepper drive pulse signal, it will drive a stepper motor to set the direction of rotation of a fixed angle (ie, step angle). You can control the number of pulses to control the angular displacement, so as to achieve the purpose of accurate positioning; and you can control the pulse frequency to control the motor rotation speed and acceleration so as to achieve the purpose of speed.
2.What kinds of stepper motor?
Stepper motor of three types: permanent magnet (PM), reaction formula (VR) and a hybrid (HB)
Permanent magnet stepper usually two-phase, torque and smaller, step angle of 7.5 degrees or 15 degrees;
Reaction is generally three-phase stepper, can achieve high torque output, step angle of 1.5 degrees, but the noise and vibration are great. In Europe and other developed countries, the 1980s have been eliminated.
Hybrid stepper is a mix of permanent and reactive advantages. It is divided into two phases, phase and five phase: two-phase step angle of 1.8 degrees, three-phase step angle of 1.2 degrees while the general five-phase step angle of 0.72 degrees.
3 What is holding torque (HOLDING TORQUE)?
Holding torque (HOLDING TORQUE) refers to the stepper motor is energized but no rotation, the stator locked rotor torque. It is a stepper motor of the most important parameters, usually the stepper motor at low speed torque to keep close. As the stepper motor output torque increases with the speed constant attenuation, output power increases with the speed of change, it becomes a measure to maintain torque stepping motor is one of the most important parameters. For example, when people say 2N.m stepper motor, in the absence of special circumstances described refers to 2N.m holding torque stepper motor.
4 What is the positioning torque (DETENT TORQUE)?
Detent torque (DETENT TORQUE) refers to the stepper motor is not energized, the stator locked rotor torque. Since the reaction is not stepping motor rotor permanent magnet material, so it does not DETENT TORQUE.
5 How much precision stepping motor? Whether cumulative?
General stepper motor step angle accuracy of 3-7%, and does not accumulate.
6 stepper motor surface temperature is allowed to reach much?
First, the stepper motor causes the motor temperature is too high magnetic demagnetization, resulting in loss of torque down even further, so the motor surface temperature should be the maximum allowed depending on the motor magnetic demagnetization points; Generally speaking, the magnetic demagnetization points are above 130 degrees Celsius, some even as high as 200 degrees Celsius, so the appearance of stepper motor temperature is 80-90 degrees Celsius completely normal.
7 Why torque stepper motor with the speed increasing decline?
When the stepping motor rotates, the inductance of the motor windings of each phase will form a reverse electromotive force; the higher the frequency, the greater the reverse electromotive force. In its role, the motor with the frequency (or speed) increases while the phase current decreases, resulting in decreased torque.
8 Why stepper motor speed can be normal operation, but if more than a certain speed will not start, accompanied by howling?
Stepper motor has a technical parameter: load starting frequency, ie stepper motor with no load to start the normal pulse frequency, if the pulse frequency is higher than this value, the motor does not start properly, you may lose steps or stall. In the case of a load, start frequency should be lower. If you want the motor to achieve high-speed rotation, the pulse frequency should speed up the process, which starts lower frequency, and then at a certain acceleration rise to the desired frequency (motor speed from low rise to high speed).
9 How to overcome the two-phase hybrid stepping motor at low speed vibration and noise?
Stepper motor rotation speed vibration and noise big is its inherent shortcomings, the following scheme can be used to overcome general:
A. If the stepper motor is just operating in resonance, by changing the transmission gear ratio to avoid mechanical resonance;
B. use with subdivision function drive, which is the most common and easiest method;
C. replaced with a smaller step angle stepping motor, such as three-phase or five phase stepper motor;
D. replaced by AC servo motor, can be almost completely overcome the vibration and noise, but higher costs;
E. on the motor shaft plus magnetic dampers, such products already on the market, but the mechanical structure of a larger change.
10 microstepping driver whether the number of segments to represent accuracy?
Breakdown of stepper motor technology is essentially an electronic damping techniques (please refer to the literature), and its main purpose is to weaken or eliminate low-frequency vibration of the stepper motor to improve the accuracy of the motor running with only one functional subdivision. For example, 1.8 ° step angle of two-phase hybrid stepping motor, if the subdivision driver breakdown of the number is set to 4, then the motor running each pulse resolution of 0.45 °, the accuracy of the motor can reach or approach 0.45 °, also depends on the breakdown breakdown of the drive current control accuracy and other factors. Breakdown of different manufacturers drive accuracy may vary considerably; subdivision greater precision control more difficult. To one hundred Glasgow phase hybrid stepping motor to illustrate: Benguela hundred AC servo control principle will be applied to the three-phase hybrid stepping motor drive system, the input of 220VAC rectified into 325VDC, then by pulse width modulation stepped into a three-way 325V sinusoidal current, which flows at fixed timings were three-way winding, each of which corresponds to the motor rotation step ladder. Drive by changing the output frequency of the sinusoidal current to change the motor speed, the number of steps per revolution of the output of each step to determine the angle of turn, which is stepped sinusoidal current (PWM).
11 four-phase hybrid stepping motor driver series connection and connection method and what is the difference?
Four-phase hybrid stepping motors are generally two-phase driver to drive, so a connection can be used in series connection or parallel connection method will be four-phase motor connected as two-phase use. Connected in series generally lower motor speed to suit the occasion, this time need driver output current is 0.7 times the motor phase current, and thus a small electric heat; and connection method is generally used where high motor speed (also known as high-speed access France), the required driver output current is 1.4 times the motor phase current, and thus a larger motor heat.
12 How to determine the stepper motor driver DC power supply?
A. Determination of the voltage
Hybrid stepping motor driver power supply voltage is generally a wide range (eg IM483 supply voltage is 12 ~ 48VDC), the supply voltage is usually based on the work of the motor speed and response requirements to choose. If the motor operating speed higher or faster response to the request, then the voltage values are high, but note that the ripple voltage can not exceed the maximum input voltage of the drive, otherwise it may damage the drive.
B. Current Determination
Power supply current is generally based on the output of the drive current I to determine. If a linear power supply, the power supply current is generally preferable to I 1.1 to 1.3 times; if a switching power supply, power supply current is generally preferable to I 1.5 to 2.0 times.
13 hybrid stepping motor drive signals off FREE generally in what circumstances?
When the signal is FREE offline is low, the drive output to the motor current is cut off, the rotor is in a free state (offline). In some automation equipment, uninterruptible power if the driver in case the request directly to motor shaft rotation (manual mode), it can be FREE signal is low, the motor off, for manual operation or adjustment. Manual is complete, then FREE signal is set high in order to continue automatic control.
14 If a simple method to adjust the two-phase stepper motor direction of rotation after power?
Simply drive motor and wiring A + and A-(or B + and B-) can be reversed.
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