Ripple-Free Torque Control of Servo Motor Considering Voltage and Current Limitation
Aiming at the problem of large ripple of brushless motor sinusoidal current torque control in servo system,this paper presents a ripple-free torque control of brushless servo motor under arbitrary back electro-motive force waveform,which realizes the minimum power loss of motor driver in limited voltage and current range.Firstly,the motor model within the limited voltage and current range is established,and the unequal constraint conditions of the voltage and current range boundary are derived.Secondly,the Lagrange multiplier method is used to solve the equivalent quadratic programming problem,and the optimal torque control strate-gy is proposed.Finally,three kinds of experimental verification are carried out on the experimental platform of three-phase 18-pole synchronous motor.The results show that the proposed finite torque optimization con-troller can still achieve accurate torque control and output expected torque when the phase voltage and current are saturated.When a single-phase fault occurs,the fault phase can be isolated,and the non-fault phase can a-chieve the expected torque output by optimizing the excitation current,which reduces the torque ripple.
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