Research On High Performance Driving Control System Of Hand Drill Based On Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor has the characteristics of high energy conversion rate,high power density and simple structure.It is inseparable from the use of permanent magnet synchronous motor in the fields of aerospace,defense science and technology and civil appliances.In civil appliances,hand-held drills have more use in production and life.Conventional hand-held drills use DC brush motors,but they limit the range of applications because they generate sparks during operation and easily disperse toner particles.In this paper,the permanent magnet synchronous motor is used as the power device of the hand-held drill,which avoids the generation of electric spark and toner particles,and expands the application range of the hand-held drill.And because of the characteristics of the permanent magnet synchronous motor,the volume and weight of the hand drill can be reduced,and the use burden is reduced.Hand-held drills are used as civilian electrical appliances,and in order to obtain the market,it is necessary to reduce the cost as much as possible.In this paper,the sensorless vector control technology and single-resistance current reconstruction technology for permanent magnet synchronous motor are studied by using the lower cost control strategy.In this paper,the basic structure of permanent magnet synchronous motor is analyzed firstly,and the mathematical model of permanent magnet synchronous motor in three-phase stationary coordinate system,two-phase rotating coordinate system and two-phase stationary coordinate system is established.Then the transformation strategies in different coordinate systems are analyzed and the transformation equations are given.Finally,the research and analysis of space vector modulation technology.For the sliding mode observer,the problem of "chattering" is easy to occur in the process of estimating the back electromotive force.This paper uses the hyperbolic tangent variable saturation function to replace the traditional constant switching function to reduce the "chattering" of the system.Since the cutoff frequency of the low-pass filter cannot be adaptively changed,a variable-pass filter is designed to make the resulting back electromotive force more accurate.Because the use of low-pass filters introduces phase delays,the mechanism for compensating rotor position based on rotational speed is designed to make rotor position estimation more accurate.In this process,the state equation of the hyperbolic tangent variable saturation function sliding mode observer is designed.The motor back electromotive force information is estimated based on the current and voltage information,and the motor position and velocity information is estimated based on the obtained back electromotive force information.Finally,in the Matlab/Simulink simulation environment,the hyperbolic tangent variable saturation function sliding mode observer is verified.Aiming at the problem that the traditional single-resistor current reconstruction technology will cause the PWM waveform to be asymmetrical and the current harmonics increase and the PWM period increases,the speed regulation interval is reduced.A new vector insertion method is proposed.Under the premise of ensuring sufficient sampling time,it not only ensures that the PWM period is not increased,but also ensures the symmetry of the PWM waveform in one cycle.In this process,the basic principle of single-resistor current sampling is first introduced,and it is difficult to accurately measure the three-phase current in the low-modulation area and the sector boundary area faced by single-resistance current sampling.The traditional phase shifting method and vector interpolation method are introduced,and a new vector interpolation method is proposed.In the low modulation region and the sector boundary region,the new vector interpolation method is studied and demonstrated.Finally,the single-resistor current reconstruction technique based on the new vector insertion method is verified in the Matlab/Simulink simulation environment.After the above simulation research,use TMS320F28027 as the main control chip to build a software and hardware experimental platform.Firstly,the hardware structure of the handheld drilling control board based on permanent magnet synchronous motor is summarized.Then the software design idea of the control system is introduced.The algorithm is implemented in CCS8.3 using C language.It can be seen from the experimental data that the controller designed in this paper has better starting performance,better adaptability to rotation speed change and better robustness.At high speeds,the estimated rotor position information is substantially consistent with the actual position information.High performance control of hand held drills is possible.