This is information on the basics of stepping motors and stepper motion control. The following will give you a brief but general understanding of the operation of stepping motors.

Part one

Types of drivers -

L / R driver

A stepping motor is the nameplate rated voltage and current based on coil resistance and maximum power (torque) the case can dissipate. The resistance and inductance produce a time constant for charging the torque coils. The voltage and time constant determine the maximum speed of stepping motor. If the stride frequency is faster than the charging time, then the torque will be reduced. If the rated voltage is applied, the stepper motor is said to be set to L / R.

If reducing resistors, equal to the resistance of the stepping motor, is inserted in series with the coils, then the configuration is L/2R. Also twice the voltage applied across the stepping motor. This will decrease load times (faster) and increase the torque to the specific step rates. However, the resistors dissipate energy waste as a stepping motor.

Bi-level unipolar drivers uses two voltage levels. The higher voltage is switched on by an explosion (the kicker pulse) at the start of each step. Bipolar integrated circuit obsolete driver L / R and Bi-levels.

Switch-mode stepping motor drivers

In switching drivers, current control circuits (sense resistor and comparator) are inserted in series with the stepping motor windings and a higher rated voltage is applied. The direction of the coil and then quickly turns the circuit on / off to regulate the continuous coil current (constant current). This technique is called chopping or switch mode. Two to fifty times the rated voltage is applied across the stepping motor. The resulting performance (speed) controller is equivalent to L/50R L/2R. One second preset selectors to reduce the current when the step motor is not rotating (Park), otherwise the engine is raised to the maximum temperature at rest. Parking permits the stepping motor operating current (torque) to increase (overdrive) on the basis of a reduced rate system cycle. The current of a switch is easily adjusted by varying the reference voltage for comparison.

Motor Step Angle Reduction - half full, and Micro-Step

If the two coils are equally energized (full step), the rotor is based on the vector between the two fields intersect in the neutral (dead band) region. If a coil is de-energized (zero current), the sweep of the rotor to a position in the center of the field of energized.
Alternatively inserting of this condition (a coil off) in the sequence step by step (half step) minto the stepping sequence (half step) steps the motor a total of eight unique positions, four half and four full. By controlling the reference voltage in a chop-per unit, both drivers of the coil with a dual D / A converter and then step by step output current coil of 100 (full) to 0 (half) percent, the stepping motor microstep between these two pole positions.

Microstep resolutions typically increases stepping motor 4 to 64 times. The D / A of the table must match the distributor guassian stepping motor, a function of stepping motor quality and magnet style.

Microstep simply based on a sine / cosine measures not equidistant as a sine function is a curve guassian. Also, microstep does not improve the accuracy basis of a stepping motor, depending on the number of rotor teeth and manufacturing quality.

Translators - Step and Direction

The phase polarity signals (sequence of steps) between the conductor and the coils are based on the step function that can take the form of logic gates or memory (step table). If this logic is configured to increase a single pulse (clock), the circuit is called a translation controller or step / direction driver. The direction input controls the direction of the sequence. A driver translates easily connected to a source of clock pulses (pulse generator) called an indexer or controller.

Intelligent Motion Control - Indexers and Controllers

The controllers are processor or logic circuits (programmable motion) that accept input control or a switch. The specific distance from the rotation (number of steps), the spped at which pulses are emitted (rate), and a function of increases in speed (slope) is preset or input to the controller. The function of the slope (ramp) allows the stepping motor to accelerate to a speed exceeding the speed instant stop and start. In this case, an initial velocity (first) and a top speed (slew rate) is input. The controller accelerates the stepping motors through movement and slows to a stop after the current number of steps (the target). Ramp allows a stepping motor to advance through the resonance bands. Open Loop Control - Homing and detection of slippage in the normal system of movement, the stepping motor steps back initially to a reference position (home) is detected and the position counter in controller is reset. The stepping motor then moves to the positions of criminality or decrease the counter position (absolute movement) or several times by bicycle to sell a fixed amount (incremental). In the open loop control, is conditional that the load is within the engine speed and torque range. A positioning system when the sensor successfully returned home under the command (the slip detection), is said to operate more or less zero steps (no error).