Research On Sensorless Vector Control Of Outer Rotor Permanent Magnet Motor In Full Operating Range

The direct-drive system of outer rotor permanent magnet synchronous motor（ORPMSM）is widely used in mining transmission belts,electric vehicles,wind power generation and other fields because of a series of advantages such as high energy efficiency,high power factor,high efficiency and cost saving.However,in the vector control system of OR-PMSM system,the rotor position signal is needed to synchronize the stator and rotor rotating magnetic fields,and the speed information is needed to control the speed loop,and the above signals need to be obtained by high-precision sensors,which leads to a series of problems such as high cost and high failure rate of the vector control system,while the sensorless control technology can effectively overcome the above problems,thus it is great significance to research the low-speed and high-torque OR-PMSM sensorless control technology for mining.The main research contents of this paper are as follows:Firstly,the mathematical models of the outer rotor surface permanent magnet synchronous motor（OR-SPMSM）in three-phase stationary coordinate system,two-phase stationary coordinate system and three-phase synchronous rotating coordinate system are established,and the vector control system of the OR-PMSM is described.Secondly,a theoretical analysis is conducted to confirm the shortcomings of the sliding mode observer based on the counter-electromotive force,and it is concluded that it has a series of problems such as serious chattering problem,poor zero-low speed tracking performance,and reliance on low-pass filter,and a super-twisting sliding mode observer based on the permanent magnet flux linkage is proposed,which effectively overcomes the above shortcomings.And the effectiveness and strong anti-disturbance ability of the proposed scheme are verified by simulation.Finally,the theoretical analysis of the traditional quadrature phase-locked loop and unitized quadrature phase-locked loop demonstrates that they have a series of problems such as 180° estimation error when the motor is reversed,poor dynamic performance,and poor disturbance reject performance,etc.A fourth-order linear extended state observer phaselocked loop with compensation mechanism is proposed to effectively overcome the above deficiencies.However,this phase-locked loop still has the problem of narrow operating range.A dual fourth-order linear extended state observer phase-locked loop with compensation mechanism is proposed,which can provide accurate rotor position and speed information in the full speed range including zero and low speed range.A comparative analysis is also performed by simulation,the simulation results show the effective improvement of the proposed phase-locked loop in terms of operating range,dynamic performance and disturbance reject performance.