DC motor control

DC no brush motor of control principle, to let motor turned up, first control Department on must according to Hall-sensor induction to of motor rotor where location, then in accordance with stator winding decided opened (or close) for flow device (inverter) in the power transistor of order, inverter in the of AH, and BH, and CH (these called arm power transistor) and the AL, and BL, and CL (these called Xia arm power transistor), makes current order flows through motor coil produced forward ( Or the reverse) rotating magnetic field and rotor magnets of interaction, so you can make the motor clockwise/counter by turning. When the rotor rotates to Hall-sensor when sensing the location of another set of signals, control and then open the next set of power transistor, and so the motor can continue to turn in the same direction until the control unit has decided to stop of the rotor power transistor is closed (or under the arm of power transistor); reverse motor rotor power transistor to open opposite order.

Basically the open method can be for example a power transistor is as follows: AH, BL group → AH → BH, CL, CL one group a set of → BH, AL group → CH, set AL → CH, BL a group, but it never goes into AH, AL either BH, BL or CH, and CL. In addition because the electronic parts always have the response time of the switch, so the power transistors in closed and open account of staggered hours to parts of the response time, or when the upper arm (or under the arm) has not been completely closed, under the arm (or upper arm) is turned on, the result is the upper and lower arm short-circuit power transistor burned.

As the motor spins up, control unit according to the drive's speed and rate of acceleration/deceleration of the composition of the command (Command) and Hall-sensor to signal change faster than (or by a software algorithm) again decided that the next group (AH or AH or BH, and CL and the CL, and BL or......) The switch breakover, and conduction time. Open long enough, speed over the short, this part of the work done by the PWM. PWM is a mode of determining motor speed is faster or slower, how the PWM to achieve a precise speed control core.

Speed control of high speed CLOCK resolution must take into account the system adequate to gain control of software instructions time, additional Hall-sensor signal change information access also affects the processor performance and judgment accuracy, timeliness. Low speeds especially slow starting because of the speed control back to the Hall-sensor signal changes more slowly, how to capture signals, processing time and electric characteristics of appropriate control parameter value is very important. Return or speed changes the encoder as a reference, the increased signal resolution in order to get better control. Motor to run smoothly and responds well, P.I.D. proper control, it also cannot be ignored. Mentioned earlier is a closed-loop control of brushless DC motor, so the feedback signal would be tantamount to telling Control Division, the motor speed range target speed or how much worse, this is the error (Error). Known error compensation for natural, there are traditional ways of engineering control P.I.D. control. But control of the State and the environment is complex and changeable, to control the rugged durability factor to consider is not the traditional engineering controls can be mastered, so fuzzy control and expert system and neural networks will be integrated into intelligent P.I.D. control of critical theory.