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tantially constant , and does not require an external resistor , sampling resistor is very small , so the power consumption of the entire system is very small , power efficient, which is widely applied constant current chopper circuit .

Broken down by controlling the motor drive circuit is the current in each phase winding size and proportions , so that the step angle is reduced to a fraction of the original to several tenth . Subdivision driver can greatly improve the smooth running of the stepper motor to improve the uniform nature , reduce or even

At present, foreign control of the stepper motor and drive is an important development direction is extensive use of a dedicated chip , the result is greatly reduced drive size, significantly improve the overall performance. Typical chip has two types: one chip is the core of hardware and microcode procedures to ensure reasonable stepper motor acceleration and deceleration process , while completing Comptroller walking , reversing etc. Used for open-loop stepper motor to achieve a reasonable acceleration and deceleration process can be run to reach higher frequencies without losing step or overshoot. The use of such ASIC , can drive 3-5 phase circuit , selectable excitation mode , speed precision , set wide speed range , acceleration and deceleration of the transition time and steepness of the rise can be selected according to the load , in addition to single-step stop operation and different ways other functions. Another piece of the core is to achieve segmentation technology, currently being due to the integrated chip voltage, current capacity constraints, generally only used for small power stepper motor drive . In recent years , many foreign manufacturers have introduced a variety of stepper motor control and driver chips and a variety of different power levels of the power module by only a few dedicated chip and a power module can be constitutive

With automatic control technology, computer network communication technology in many fields of application and further development as well as digital, intelligent technology growing , more in-depth stepper motor will be applied in a wide range of fields , and the drive system will also be along with development, especially the development of the intelligent application of technology direction will be the next stage of development of the stepper motor

Can use the pulse motor speed and steering control. To prevent the occurrence of the phenomenon of death microcontroller , improve anti-jamming capability , the speed control pulse is applied to the reset terminal of the microcontroller , rather than the general I / 0 terminals. This connection can be guaranteed in each control pulse arrives, the MCU can always be activated due to a reset . When changing the CP pulse cycle, the high and low winding width will change, this change will cause the • power and power change rate change. And finally to the motor speed changes . This control method has the advantage of simple procedures . Occupy less chip resources . Reset the microcontroller can be used simultaneously to improve noise immunity. As a CP pulse input stepper motor phase windings causes a state change once. And a corresponding rotation angle. Therefore, the angle of rotation of the stepping motor can be input to determine the number of pulses of CP [ 3 ] .

The stepper motor drive circuit design methods ,