Design And Research Of Electric Forklift Ac Servo Control System Based On DSP

With the development of modern logistics technology, people have higher and higher requirement on forklift products. AC motor as the core of AC drive system will lead a new wave of electric forklift technology revolution and become forklift truck trends because of high efficiency, reliability, small size, simple structure, wide speed range, low-speed constant torque, high-speed constant-power and low maintenance costs. Meanwhile, the development of electronic technology and maturity of new control theory also makes AC servo control system from the previous analog control to an all-digital control. The digital servo motor control system can achieve precise torque control, speed control and position control, and much better than DC motor servo systems special in quickly reaction and stability. Especially using the high energy Rare-earth permanent magnets motor, the servo system have performance in torque output, small force of inertia, fast dynamic response in start-stop mode, which help promote production efficiency and forklift quality. It become the irresistible trend that the low power consume, maintenance-free, low noise motor control system is more and more used in Electric Forklift Equipments. The NC (Numerical Control) AC servo motor control systems are gradually replacing traditional DC motor servo control system and become the mainstream technology in the sewing machine drive system.First of all, the principle and model of Perrnanent Magnet Synchronous Motors (PMSM) are given, including the structure,works and mathematical model. Then the vector control theory of servo system is analyzed systematically and the Field Oriented Control(FOC) theory that d-axis current is equal to zero is selected as the main theoretical basis. It can realize the electrical decoupling between the the d and q axe with a linear torque control characteristics, and obtain relatively steady output of torque to achieve relatively wide speed range. Subsequently, according to the control principle, the composition of the various components and workflow of the servo system are analyzed.In the control theory, the traditional PID control algorithm and the traditional PID control algorithm are introduced with the emphasis on SVPWM control algorithm and a kind of dead-time compensation strategy. Mechanism of dead-time effect on the three-phase voltage source inverter is analyzed in detail. According to voltage space vector, three-phase voltage is divided into six regions and is compensated by the method of time compensation in various regions according to current direction. The results show that the compensation method can effectively improve motor current waveform distortion causing by the effect of dead zone, and enhance the output performance of the inverter.The design and research of the electric forklift AC servo control system are discussed based on DSP. A set of hardware system design is presented out based on the TI TMS320F2812 DSP digital signal processor chip as a master, and multiple parallel low-voltage high-current of the MOSFET as the power drive module. The method and realization about some key segments are elaborated. System designs a more comprehensive protection functions. For example, the external overvoltage, overheating and overcurrent protections are added in the controller design. Optocoupler isolators shielding measures are used in the power module to raise the anti-jamming capability to ensure the system safe and reliable operation. In software design, the idea of modular design method and the structure of system main program, the interrupt service program are adopted, and implementation processes of some sub-programs are proposed.Finally, this system is simulated by Simulink on the basis of the theory. The experiment platform is tested on low-speed operation of the motor. The results show that the system has good stability and the parameters are in line with design requirements. Test results show that the entire control system can meet the modern numerical control electric forklift industrial demand, and it has a high cost performance with good market prospects.