The Design Of Electrical Control System Of Ultracentrifuge

Centrifuge is mainly used to seperate blood cells, chemical products, industrial,medical, biotechnology and other industries common devices. Generally themaximumspeed of more than30,000rpm centrifuge called ultracentrifuge. With thedevelopment of technology, there are centrifuges which maximum speed is up to150,000rpm in abroad now. But the maximum speed of domestic centrifuges doesnot exceed60,000rpm, both the aspects of the machine’s maximum speed and theintelligence of the machine are big gap to foreign.This paper design the ultracentrifuge electrical control systems, including theelectrical control system hardware design and software design of electrical controlsystems. The paper focus on the design of the parts of the motor inverter control,including hardware and software.This paper studies the frequency control method of ultracentrifuge asynchronousmotors. The method of motor control is slip frequency adopted by the speed of themotor feedback. This is a closed loop control system, with high speed performance.The inverter part of the way is PAM. By PAM method can reduce the switchingfrequency of the inverter bridge’s switching devices, so that reduce the switching lossof the switching device and to suppress the generation of higher harmonics, reducepollution of the grid.This paper designs the hardware circuit of ultracentrifuge electricalcontrolsystem. The hardware circuit by function includes the motor inverter controlcircuit, door detection and rotor identification circuit, the degree of vacuum andtemperature control circuitry, storage and communications interface circuits,interactive interface power circuit, the fault detection circuit. The hardware of motorinverter control circuit design includes rotational speed detecting circuit, a rectifyingcircuit, a current, a voltage detection circuit and a control circuit, thepulsedistribution circuit and a drive circuit and other components. Motor control using themicroprocessor with STM32which is in main control board. STM32mainly tocomplete the output control signal and the current output frequency and voltage. Eachpart of the circuit of this paper has been studied and designed such that the controlcircuit isable to achieve the requirements of the ultracentrifuge. In the electricalcontrolsystem, improve the cooling chip control circuit controls more efficient andreasonable. Electrical control system added USB interface circuit for easy user access the printer.This paper designs ultracentrifuge electrical control system software. Theelectrical control system software design by module，and then call each module in themain program. Design of the main flow chart of the electrical control system, and thedesign of the program modules of each module. The software design focus on variablefrequency motor speed control software, including the detection program design ofthe speed, the current and the voltage, the function generator, and the designprogramming of speed control. Designed touch screen with the STM32MODBUSslave communication procedures and USB communication driver STM32andcommunication with the printer. Designed ultracentrifuge fault detection andprotection procedures, the proposed method can be carried out through the PCtroubleshooting for ultracentrifuge.