Research And Design Of Stepper Motor Drive Circuit

The motor drive chip is composed of CMOS control circuits and DMOS power devices,and its demand is increasing with the development of science and technology.One of the stepper motor driver chips with advantages of high precision,excellent start-stop capability and low price and its related technologies are a hot topic of current research.In this thesis,a two-phase stepper motor driver chip is designed based on the 0.18μm BCD process platform,and the normal operating voltage range is 8～52 V.The chip is based on PWM control,and it can subdivide the current on the motor winding by using the current comparison chopper drive mode,so as to realize the subdivision control of up to 32 microsteps.In addition,the chip also integrates a variety of power modules to meet the power supply requirements of each internal module.First of all,this thesis analyzes the related drive technology of the stepper motor from the overall system of the stepper motor and its working mode.Next,the overall structure of the stepper motor drive chip is determined,and the functions of each sub-module and the signal transmission path are planned,and then the important sub-modules of the chip were designed,simulated and analyzed.The key drive circuit module of the chip is driven by current,with different levels of drive current I_DRIVE and drive time t _DRIVE.After the end of the drive current phase,the drive circuit module converts to a small current to maintain the normal gate voltage state of the power MOSFETs,which can better realize the rapid charging and discharging of different gate capacitors of the external power MOSFETs and reduce voltage spikes.The on-chip power module includes pre-regulator module,bandgap reference module,linear regulator module and charge pump module.The linear voltage regulator module is composed of 1.8 V and 5 V linear voltage regulator circuits,which supply power for the on-chip digital and analog circuits respectively;the charge pump module has a voltage monitoring function to control the output voltage of the charge pump to keep it within a safe voltage range.In addition,the system also includes current detection module,level shift module,and protection module,etc.The current detection module has bidirectional detection function,which can completely detect the forward and reverse current of the winding,so as to more accurately control the opening and closing of the H-bridge power MOSFETs.Finally,this thesis conducts an overall simulation analysis of the stepper motor driver chip to further verify its system functions,and the results meet the design requirements.