Design And Verification Of The Permanent Magnet Quantitative Magnetization

In the traditional motor driving condition,the coil drives the permanent magnet in most cases.A variable current could be input to the coil to generate the desired torque,while the magnetization of the permanent magnet is fixed.This control method is suitable for scenarios where coils and magnets are required to move at a relatively high speed.However,when it comes to robot exoskeleton driving,many problems would arise.In these conditions,the robot’s joint motion speed is relatively low,and a fixed angle may be required while maintaining a constant torque.Because there is no enough counter electromotive force generated in the coil,a large current will be generated,which would cause excessive heat and waste of power.The traditional solution is to introduce a reducer or cooling system.However,new problems will be caused such as unnecessary volume,inevitable wasted power and the reducer unable be driven in the reverse direction.In response to the problems above,this paper proposes a drive mode based on permanent magnet quantitative magnetization.In this drive mode,the magnetization of the variable magnetization magnet could be regulated instantaneously as desired,and the magnetization could be maintained without inputting current.In the driving process,this variable magnetization magnet can replace the coil to generate the driving torque with periodically magnetization pulse,and the frequency of adjusting the magnetization intensity is related to the rotation speed.This feature can make it have lower power consumption and more stable performance when driving at low speeds.According to the principle of quantitative magnetization,this paper also proposes a torque model in the driving process.The pulse current that should be input can be calculated in real time for the desired torque.Multiple sets of variable magnetization magnets can achieve precise control of torque,thereby realizing external torque drive.