Jiaxi Liu

A position error compensation way for sensorless linear motor drive using high frequency injection

This paper presents a method of improving sensorless control based on the high frequency injection (HFI) for linear motor. The d- and q-axis incremental self- and mutual-inductance are determined by finite element analysis. The estimated mover position error caused by the cross-coupling magnetic saturation between the d- and q-axis is quantitatively analyzed. The error caused by filters in a HFI system is analyzed based upon filter group delay theory. A simple-to-design on-line compensation method is proposed based upon filters and cross-coupling magnetic saturation in a HFI system, which minimizes the position error. Finally, the simulation and experiment show a significant improvement in the accuracy of the mover position estimation.

The Full Digital Drive on the Voice Coil Motor Based on the Wafer Stage

this paper presents the method of a full digital drive of voice coil motor (VCM) based on the wafer stage (WS). First of all, the mathematical mode of VCM is given and the current ripple in the 2-level drive is analyzed; secondly, in order to decrease the current ripple, the 3-level drive is put forward and the different current state is gained, in which the current ripple is quantitatively analyzed; thirdly, the current loop is designed based on the two degree of freedom (2DOF) control method. The feed forward control is used to improve the current loop bandwidth in the 2DOF and the error including the VCM force ripple and hardware drift are compensated; Finally, the full digital drive experiment platform is built and the feasibility of the method is verified by experiments and simulations.

Sensorless Control of Primary Segmented Permanent Magnet Linear Motor

This paper presents a mathematical model to describe the parameter changes of the primary segmented permanent magnet linear synchronous motor (PS-PMLSM) when the mover is between segments. Then, the back-EMF observation method based on disturbance observer is proposed. The extreme of the observer and the observing errors are analyzed. Based on the addition of the observed EMF with each active segment, the full-order Luenberger speed observer with a mechanical equation is implemented in order to reduce speed fluctuation caused by the discontinuous of magnetic circuit between two segments. Finally, the experimental platform of PS- PMLSM system is established. The effectiveness of sensor-less control scheme for the PWS-PMLSM is verified by the experimental results.

Efficiency Optimization Control of Permanent-Magnet Synchronous Machines for Electric Vehicle Traction Systems

This paper investigates a method to increase the energy economy of motors for an electric vehicle (EV) traction system. The low torque region of an EV motor is frequently used in everyday urban driving. Pulse-width modulation (PWM) carrier harmonic loss accounts for a high percentage of total loss for EV motors in this region. This paper reveals the relationship between fundamental and harmonic iron current for a permanent magnet synchronous motor (PMSM) by double Fourier integral analysis and builds the global loss model of PMSM which considers about both fundamental and harmonic loss. Based on the global loss model, an efficiency optimization control strategy is proposed in this paper, which can achieve the maximum efficiency by adjusting the flux-weakening current to the optimum value in the whole operation range for EV. Comparison among different control algorithms is drawn from both analytical and experimental results, from which the effectiveness of efficiency optimization control is verified.

High-bandwidth current control for high-speed linear motor

The linear motor platform applied in the electromagnetic launch device is a high-speed motion system, motor drive system should have the characteristic of high dynamic response. Predictive current control is an effective method to improve the dynamic response of motor drive system. In order to achieve a higher current loop bandwidth, this paper presents an improved predictive current control for PMLSM based on space vector pulse width modulation (SVPWM) technology, a correction factor is introduced to reduce the response time on the basis of ensuring the system stability. Simulation and experimental results are shown to verify the feasibility and effectiveness of the proposed algorithm.

Current control for the single degree of freedom linear maglev system

The single DOF (degree of freedom) linear maglev (magnetic levitation) system is the basis of studying on the maglev guideway. Generally, the electromagnet is selected to provide the electromagnetic force, however, this force is highly nonlinear. This paper presents a linear model of the single DOF linear maglev system, and establishes the corresponding experimental platform. In order to improve the dynamic response and depress the current ripple, a predictive current control based on three-level technology is proposed. The simulation and experimental results show that the proposed method achieves excellent dynamic and static performance.

Analysis and design optimization of ironless linear permanent magnet synchronous motors with non-overlapping concentrated windings for ultra-precision positioning system

This paper presents the electromagnetic design of Ironless permanent magnet linear synchronous motor with non-overlapping concentrated windings based on the Equivalent Magnetizing Current(EMC) method. For one such motor structure we give analytical formulae for its magnetic field and thrust density and analyze to improve air-gap flux density and thrust density by varying motor design parameters. In order to minimize thrust ripple and improve thrust density, we analyze the superiority of ILPMLSM with Halbach magnet array and fractional-slot concentrated winding. The validity of the proposed technique is confirmed with 2-D Finite Element (FE) analysis.