Senin, 02 Mei 2011

Stepper motors


Stepper motors convert electrical pulses supplied to the rotor discrete movements called steps (steps). Value rating of a given stepper motor right in steps per revolution (steps per revolution). Stepper motors generally have speed and [torque] is low. Stepper motor works based pulses given to the phase windings in proper sequence. In addition, the pulses must also provide a large enough current in the coil phase. Therefore, for the operation of the stepper motor must first design a dilute sequ rationing logic to determine the sequence of phase winding motor and then using a driver (drivers) to provide the current needed by the winding phase. The following elements determine the characteristics of a stepper motor: 1. voltage. Stepper motor usually has a given voltage nominal.
1. Stress sometimes exceed the nominal voltage to obtain the required torque, but can cause overheating and shorten the motor age.
2. Barriers. Other characteristics are resistance-per-winding. These obstacles will determine the current drawn by the motor, and also had a torque curve and maximum operating speed affect the motor.
3. Degrees per step (step angle). This factor determines how many degrees the shaft will rotate for each full step (full step). Operating half-step (half step) will double the number of steps-per-revolution, and reduce the degree-per-stride. Degrees-per-step is often referred to as resolution.


A PPE ste r motor (or motor steps) are brushless, synchronous electric motor that can be made for a full rotation into a large number of steps. The motor's position cans be controlled precisely without any feedback mechanism (see Open-loop controller), as long as the motor is carefully sized to the application. The position of the motor can be controlled accurately without the feedback mechanism (see Open-loop controller), during motor carefully sized to the application. Stepper motors are similar to switched reluctance motors (the which are very large stepping motors with a reduced pole count, and Generally are closed-loop commutated.) Stepper motors are similar to switched reluctance motor (a stepping motor with a very large number of poles is reduced, and general closed-loop commutated.) Basic - Basic Operations -> Stepper motors operate differently from the DC brush motors, the which rotate Pls Their voltage is applied to terminals. Stepper motors operate differently from the DC brush motor, which rotates when a voltage is applied to their terminals. Stepper motors, on the other hand, effectively have multiple "toothed" electromagnets Arranged around a central gear-shaped piece of iron. Stepper motors, on the other hand, effectively have multiple "toothed" electromagnets arranged around a tooth-shaped piece of iron center. The electromagnets are energized by an external control circuit, Such as a microcontroller. The electromagnetic energy is through an external control circuit, such as microcontrollers. To make the motor shaft turn, first one electromagnet is given power, the which makes the gear's teeth magnetically attracted to the electromagnet's teeth. To make the turn the motor shaft, the first one electromagnet is given power, which makes gear's teeth magnetically attracted to the electromagnets tooth. When the gear's teeth are thus aligned to the first electromagnet, They Are Slightly offset from the next electromagnet. When the gear teeth is thus in line with the first electromagnet, they are slightly offset from the next electromagnet. Pls So the next electromagnet is turned on and the first is turned off, the gear rotates Slightly to align with the next one, and from there the process is repeated. So when the next electromagnet is activated and the first turned off, the gear rotates slightly to match the next, and from there the process is repeated. EACH of those slight rotations is Called a "step", with an integer number of steps making a full rotation. Each little rotation is called "step", with an integer number of steps to make a full rotation. In that way, the motor cans be turned by a precise angle. That way, the motor can be changed with the right angle. Characteristics of Stepper Motors: Stepper motors are constant power devices. As motor speed increases, torque decreases. Along with the increase in motor speed, torque is reduced. (Most motors exhibit maximum torque Pls stationary, however the torque of a motor stationary Pls 'holding torque' defines the ability of the motor to maintain a desired position while under external load). (Motor that most shows maximum torque when stationary, but the torque of the motor when the 'holding torque' ability to define a stationary bike to maintain the desired position while under an external load). The torque curve May be extended by using current limiting drivers and Increasing the driving voltage (Sometimes Referred to as a 'chopper' circuit; there are installments of chips off the shelf drivers capable of doing this in a simple manner.) Torque curve can be extended by using current limiting drivers and increasing the driving voltage (sometimes referred to as a series of 'helicopter', there are some off the shelf chip drivers are able to do this is simple). Steppers exhibit more vibration motors Than other types, as the discrete step tends to snap the rotor from one position to another (Called a detent). Steppers show more vibration than other motor types, as a discrete step tends to snap the rotor from one position to another (called detent a). The vibration makes stepper motors, DC motors Than noisier. vibrations that create noise stepper motor compared with DC motors. This changed from very bad vibration at cans Some cans speeds and cause the motor to lose torque or lose direction. This vibration can become very bad at some speed and can cause loss of motor torque or losing direction. This is Because the rotor is being held in a magnetic field is the which behaves like a spring. This is because the rotor is being held in the magnetic field behaves like a spring. On EACH step the rotor overshoots and bounces back and forth, "ringing" at its resonant frequency. At each step the rotor overshoot and bounce back and forth, "ring" at its resonance frequency. If the stepping frequency matches the resonant frequency increases then the ringing and the motor comes out of synchronism, resulting in positional error or a change in direction. If a stepped frequency matches the resonant frequency of the number of rings and motor out of synchronism, resulting in an error change of position or direction. At worst there is' a total loss of control and holding torque so the motor is Easily overcome by the load and spins Almost Freely. At worst there is total loss of control and torque hold so easily overcome by the motor load and rotate almost freely. The effect cans be mitigated by Accelerating Quickly speeds through the problems of range, physically damping (frictional damping) the system, or using a micro-stepping driver. The effect can be reduced by accelerating quickly through the various problems of speed, physical damping (damping friction) systems, or using micro-stepping driver. Motors with a Greater number of phases exhibit smoother operation Than Also those with fewer phases (cans Also this be achieved through the use of a micro stepping drives. Motors with greater number also shows the smooth phase operation compared with fewer stages (this is also can be achieved through the use of micro-stepping drive).


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