Abstract
For permanent magnet synchronous motors (PMSMs) supplied with a voltage source inverter, current control strategies are commonly implemented under the synchronously rotating reference frame. In order to simplify the system structure, three-phase currents can be measured with a single DC-link current sensor using the phase current reconstruction technique. However, it still needs to follow the conventional AC current control approach. In this paper, a DC-link current control method for PMSMs is proposed to further simplify the control system. The problem of phase current control was separated into the problems of amplitude control and phase control. Then, amplitude control was achieved using a closed-loop controller directly tracking the DC-link current; while phase control was achieved by AC-side pulse width modulation (PWM) following the phase angle of back electromotive force. The compensation for nonlinear distortion of the inverter was taken into account during the control process. Finally, the proposed method realized three-phase current control with a single current sensor and controller, and achieved the purpose of electromagnetic torque control. Experimental results demonstrate the effectiveness of the proposed method.
Highlights
Owing to their advantages of high power density, high torque inertia ratio and wide speed range, permanent magnet synchronous motors (PMSMs) have been widely used in motion control fields such as aerospace, weaponry, industrial robots, and computer numerical control (CNC) machines [1,2,3,4].Generally, PMSMs are powered by a three-phase voltage source inverter (VSI) [5,6]
We describe how amplitude control of phase currents is implemented on the DC side of VSI by tracking the designed reference DC-link current, and how phase control is implemented by AC-side pulse width modulation (PWM) following the phase angle of back electromotive force (EMF)
Considering that the torque performance of PMSM is susceptible to nonlinear distortion of VSI in low modulation area of PWM, a DC-DC converter is usually used to provide DC-link voltage adapting to the operating point of PMSM, especially for motor drives with a wide speed range [31,34]
Summary
Owing to their advantages of high power density, high torque inertia ratio and wide speed range, permanent magnet synchronous motors (PMSMs) have been widely used in motion control fields such as aerospace, weaponry, industrial robots, and computer numerical control (CNC) machines [1,2,3,4]. PMSMs are powered by a three-phase voltage source inverter (VSI) [5,6]. According to rotor position and speed, VSI supplies terminal voltages to stator windings of PMSM through PWM to generate stator currents. The electromagnetic torque of PMSM is generated by the interaction between rotor permanent magnet and alternating magnetic field formed by stator currents [7]. Research on current control strategies has become a constant theme in the field of PMSM servo control
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