Subdivision drive control of stepping motor
Step motor is limited by its own manufacturing process, such as the size of step angle is determined by the number of rotor teeth and running beats, but the number of rotor teeth and running beats is limited, so the step angle of step motor is generally large and fixed, the resolution of step is low, lack of flexibility, vibration in low-frequency operation, noise is higher than other micromotors, which makes the physical device easy to fatigue or damage. These shortcomings make the stepping motor can only be used in some occasions with lower requirements. For those occasions with higher requirements, only closed-loop control can be adopted, which increases the complexity of the system. These shortcomings seriously limit the effective use of stepping motor as an excellent open-loop control component. To a certain extent, subdivision drive technology effectively overcomes these shortcomings.
Stepping motor subdivision drive technology is a kind of drive technology developed in the middle of S, which can significantly improve the comprehensive performance of stepping motor. American scholars first proposed the control method of stepping angle subdivision at the annual conference of incremental motion control system and devices. In the following 20 years, the subdivision drive of stepping motor has been greatly developed. It gradually developed to be fully mature in the 1990s. China's research on subdivision driven technology started at the same time as foreign countries.
In the mid nineties, it developed greatly. It is mainly used in industry, aerospace, robotics, precision measurement and other fields, such as photoelectric theodolite for tracking satellite, military instruments, communication and radar and other equipment. The wide application of subdivision drive technology makes the phase number of motor not limited by the step angle, which brings convenience to product design. At present, in the subdivision drive technology of stepping motor, chopper constant current drive, instrument pulse width modulation drive, current vector constant amplitude uniform rotation drive control are adopted, which greatly improves the running accuracy of stepping motor, and makes stepping motor develop to high speed and precision in the field of medium and small power application.
At first, the control of the phase current of stepping motor is realized by hardware. Usually, two methods are adopted, multi-channel power switch current is used for power supply, and the current is superposed on the winding. This method makes the power tube loss less, but because of the number of circuits, there are many devices and large volume.
Firstly, the pulse signal is superposed, and then the step current is obtained by the linear amplification of the power tube. The advantage is that the devices used are few, but the power consumption of the power tube is large, and the power of the system is low. If the tube works in the non-linear area, it will cause distortion. Because of its own insurmountable shortcomings, these two methods are rarely used at present.