Motor with DSP control is an important development direction

Net electric motor dental chair chooses rare earth permanent magnet brushless dc motor drive system, this system has been developing rapidly in recent years on BLDC motor with DSP control technology, chooses a DSP controller to achieve two rare earth permanent magnet brushless dc motor control, has the characteristic of low cost and high performance. Rare earth permanent magnet brushless motor with high efficiency, good performance, simple structure brief, heat dissipation, low noise and so on characteristics, meet the medical industry, the special requirements of all aspects of medical devices. And, in rare earth permanent magnet brushless motor driven linear drive tissue replacement brush motor driven organization and single-phase ac asynchronous motor driven organization, has great social meaning and broad market prospect. Electric dental chair with two degrees of freedom, pitching and lift. The servo system, two rare earth permanent magnet brushless dc motor as main components, motion control for two degrees of freedom, were driven. Motor control part only choose a DSP ( Digital signal processor) Chip TMS320LF2407A complete control of the two brushless motors, make full use of the DSP on-chip resources, on the PWM input all the two motors chooses DSP supply, eliminating the logic chip, improve the reliability of the system. Through the SPI chip serial peripheral extended memory chips, choose FRAM ( Nonvolatile memory) With electrical maintenance functions, complete in closing the orientation of the electric power to the electric chair. Additional motor motor power is 55 w, the extra voltage 24 V, operation condition for short-term operation, extra speed 1800 RPM, planning way according to the square wave planning, 12 slot motor for two pairs. Trough for trapezoidal fan groove, winding way for three-phase star six conditions, tank full rate was 52%, the rotor magnet steel bonded ndfeb, radial magnetization. Detailed parameters are as follows: magnetic steel Br> 6000 gs, Hc> 5000Oe,[ BH) max> 8毫克。 Oe,Hjc> 10000Oe。 The finite element analysis, the electromagnetic torque motor practice of 0. 2394 n· m。 Master controller, this controller unit selects TI company's TMS320LF2407A DSP chip, the master control unit needs testing motor current signal and rotor position signal, and to supply driven plate with six-way PWM drive signal, so the control of a brushless dc motor, needs 6 PWM output, all the ADC conversion, three capture unit. About the TMS320LF2407A microprocessor, because it has two things manager ( EVA and EVB) , every thing manager has three can capture unit and output PWM 6 road, so the chip can directly supply for two brushless dc motor control signals. For more sophisticated control chip peripheral circuit, but it has large application memory, therefore, related to hardware, to be completed in view of the flexible control of the motor, focusing on software. Link of drive control system of the motor drive circuit selects the whole bridge structure, through to the six power device, control, modulation of motor voltage and current waveform. By using TMS320LF2407A contains four separate 16 general timer, six full complete motor voltage PWM modulation comparator. TMS320LF2407A embedded programmable control dead zone, any one of six full comparator with general timer, dead zone control unit used to attack a programmable dead zone and output polarity of the PWM output. A total of 12 road PWM output. Every six output can be used to control brushless dc motors, DSP control of the two motors. Choose IRF540 power tube, the equipment the highest operating voltage of 100 v, current 28 a biggest homework, maximum power 150 w loss, completely meet the requirements of the system power; Fly-wheel diode D1 ~ D6 choose quick restore diode; Capacitor C1 ~ C3 to absorb the peak voltage on the dc bus, bus to avoid too high breakdown voltage power tube; Resistance R2 to detect motor current on the dc bus, avoid motor over-current failure, the over current signal Isence by processing input level to the front of the power of the bridge after driving chip and DSP processors, when the over-current blocking gate drive signal in the time. Power tube of the level before the driver and the use of IR company motor driver chip IR2130, the chipset driver, dead zone, over-current maintenance function and integration, such as using a single power supply can complete the drive of six power tube, when use is very convenient, especially suitable for small power drive. Software on the basis of the nature of function, the software is divided into the following several main modules: initialization module, main program initialization module, _c_int0) , EVA initialization module, EVA_INIT) Initialization, EVB module ( EVB_INIT) ; Motor launch module: A launch module ( MOTORA_START) The motor launch module (B MOTORB_START) ; The reversing module: motor reversing A module ( COMMUTATION_A) B, motor commutation module ( COMMUTATION_B) ; A hall of hall signal capture module: motor signal capture module ( CAPIN_A) B hall signal capture module, motor ( CAPIN_B) ; A keyboard input keyboard analysis module: motor analysis module ( KEY_ANALYSE_A) B keyboard input, motor analysis module ( KEY_ANALYSE_B) ; The PID module ( _PID) , bearing the memory module ( REM) 。 Software main body chooses prevalent in engineering modular sequence structure, hall signal capture and selection of PID regulating suspension control methods. System initialization of DSP system registers, I/O port, and the set of suspension system, two of the motor running condition obtained by the analysis module, keyboard according to the situation, launched resolution motor is in operation, or a halt. Motor operation condition by the global variable RUN_STATE_A and RUN_STATE_B showed that 088 h showed that motor running, 00 h indicates that electric motor, 0 FFH suggests that motor stalling. Rare earth permanent magnet brushless dc motor with DSP control technology, is an important development direction of the brushless motor.