BLDC Drive Circuit Design And Application

Brushless DC motor has been considered as the most development potential and application prospects motor in the 21 st century.Brushless DC motor has been use for the aerospace,national defense,scientific research,industry,people's livelihood and other aspects.Compared with brush motor,brushless DC motor has been controlled by digital system,and it improve well for the noise,sparks,fever and other issues,because brushless DC motor has a better speed control features,so it's a favorite.In the near future,brush motor could be replaced by the brushless DC motor.First of all,through investigate current situation about the domestic and foreign studies for the brushless DC motor,through discusses studying significance for driving system of brushless DC motor,established this subject.Secondly,through researching domestic and foreign mainstream brushless DC motor drive system,we set out this design mode and performance indicators for drive circuit application.This design using double closed loop control mode,The design of the hardware using the master circuit and driver circuit and inverter circuit design mode.We using hall position sensor and optocoupler isolation circuit in the speed loop design.We using sampling resistor and current amplifier for the current loop feedback circuit,and this current amplifier are used to be integrated inside in driver chip.In power,different voltages are provided to different circuits.And we add error protection alarm circuit in the drive circuit,do this way,it can protect the circuit in a better way.We using open loop and closed loop mode in the software design.In terms of programming,the software part of this design idea is as much as possible change some functional modules that often written in the function sub-module,and some do not need to frequently change function in the main program,there are many benefits to do this for the debugging and function change.The software uses PID control algorithm.The part of software functional modules as follows: soft-start module,open-loop control module,pulse conversion module,counting commutation module,PWM generating module,closedloop speed module,hall capture module,real-time speed calculation module,PID algorithm module.Finally,when we completing the design and commissioning for the drive circuit,we checking the main circuit,drive circuit,inverter circuit,hall feedback circuit and other related circuit pin waveform and motor operation to get this result that our design about the drive circuit is correct.Then,for the current market,brushless DC hand drill is a blank,so for this situation,we do some application development for brushless DC hand drill,and in the laboratory conditions,we complete the electric drill,electric screwdriver function using this application,and this brushless DC hand drill had an able to drill,screw,remove screws.And it can meet the part of the national standard requirements for the drill,which proves that the drive circuit meets the performance requirements.This design is follow the digital trends,based on the digital control technology,we design and completed a motor drive circuit.And because the design used this power management chip and power tube has this feature that in a range of voltage can work properly,so that the design of this drive circuit can also be completed in a certain voltage range and normal work.Another feature of this design is that the closed-loop control of the software design is controlled by open-loop control to the closed-loop,so that this design can be applied to both open-loop control systems and closed-loop control systems.As a result of these two characteristics,greatly increased the scope of application for the drive circuit,so that this drive circuit has a strong applicability.