A Design Of High-power And Torque-limited Electric Wrench Driver Based On Direct Torque Control

This paper designs a high-power and torque-limited electric wrench driver based on direct torque control and hopes that when the input is single-phase power frequency alternating current,the electric wrench can output limited torque by DTC according to the pre-set speed.And this electric wrench is able to limit the Maximum torque and prevents the damage to the device.Also the electric wrench diver has a function of over-current and over-voltage protection,and protects itself from voltage surges.This paper further studies the electric wrench diver,and goes in for the following jobs:(1) The electric wrench is modeled in ABC static coordinate and a{3 static coordinate,and principle of DTC is stated with voltage equations,flux linkage equations and motion equations. Parameters of the electric wrench are measured by Locked-rotor test and no-load test.Under Simulink platform,the electric wrench diver is modeled based on DTC,the PID parameters of speed PID regulator are adjusted,each part of the model from motor-start to stable state is analyzed and DTC feasibility applied to the electric wrench diver is verified.(2) According to the hardware of the electric wrench diver system,the rectifier circuit, inverter circuit,current detecting circuit,voltage detecting circuit, over-current protection circuit, over-voltage protecting circuit and IGBT drive circuit are designed. The software of the electric wrench diver system is written,the interrupt service routine under the circumstance of VC6.0 is compiled and this prove that the program has the ability to control the known flux Linkage and torque.(3) The the electric wrench diver system is made to output 75Hz alternating current by array method and heavy-load experiments are done witch validates hardware reliability of the power system.The DSP’s modules are configured,the flux Linkage and torque’s data is saved onto the DSP to observe the electric wrench diver system outputing PWM voltage vector witch proves that the system has the processing power capacity to the motor’s current state.(4) At last, the closed-loop electric wrench driver system is debugged and the problem of the flux Linkage observer is found.From this work,the paper verifies DTC feasibility applied to the electric wrench driver,and finds out disadvantages of u-i Flux Linkage Observer witch provides us guidance for further study.