High-frequency issues using rotating voltage injections intended for position self-sensing

The rotor position is required in many control schemes in electrical drives. Replacing position sensors by machine self-sensing estimators increases reliability and reduces cost. Solutions based on tracking magnetic anisotropies through the monitoring of the incremental inductance variations are efficient at low-speed and standstill operations. This inductance can be estimated by measuring the response to the injection of high-frequency signals. In general however, the selection of the optimal frequency is not addressed thoroughly. In this paper, we propose discrete-time operations based on a rotating voltage injection at frequencies up to one third of the sampling frequency used by the digital controller. The impact on the rotation-drive, the computational requirement, the robustness and the effect of the resistance on the position estimation are analyzed regarding the signal frequency

Sensorless Control of Switched-Flux Permanent Magnet Machines

This thesis investigates the sensorless control strategies of permanent magnet synchronous machines (PMSMs), with particular reference to switched-flux permanent magnet (SFPM) machines, based on high-frequency signal injection methods for low speed and standstill and the back-EMF based methods for medium and high speeds

Improved signal injection based sensorless technique for PM brushless AC drives

The accuracy of rotor position estimation in the conventional signal injection based sensorless control of permanent magnet brushless AC drives depends on the load current. This paper proposes an improved method, which significantly reduces the estimation error by accounting for the cross-coupling effect between the d-and q-axes. The conventional and proposed methods are described and their performance is compared by both simulation and experiment

A Novel PMSM Hybrid Sensorless Control Strategy for EV Applications Based on PLL and HFI

In this paper, a novel hybrid sensorless control strategy for Permanent Magnet Synchronous Machine (PMSM) drives applied to Electric Vehicles (EV) is presented. This sensorless strategy covers the EV full speed range and also has speed reversal capability. It combines a High Frequency Injection (HFI) technique for low and zero speeds, and a Phase-Locked Loop (PLL) for the medium and high speed regions. A solution to achieve smooth transitions between the PLL and the HFI strategies is also proposed, allowing to correctly detect the rotor position polarity when HFI takes part. Wide speed and torque four-quadrant simulation results are provided, which validate the proposed sensorless strategy for being further implemented in EV.Peer ReviewedPostprint (author's final draft

Multiphase induction motor drives - a technology status review

The area of multiphase variable-speed motor drives in general and multiphase induction motor drives in particular has experienced a substantial growth since the beginning of this century. Research has been conducted worldwide and numerous interesting developments have been reported in the literature. An attempt is made to provide a detailed overview of the current state-of-the-art in this area. The elaborated aspects include advantages of multiphase induction machines, modelling of multiphase induction machines, basic vector control and direct torque control schemes and PWM control of multiphase voltage source inverters. The authors also provide a detailed survey of the control strategies for five-phase and asymmetrical six-phase induction motor drives, as well as an overview of the approaches to the design of fault tolerant strategies for post-fault drive operation, and a discussion of multiphase multi-motor drives with single inverter supply. Experimental results, collected from various multiphase induction motor drive laboratory rigs, are also included to facilitate the understanding of the drive operatio

Design of an easy tunable soft sensor for real-time speed and position estimation of PMSM

Volume 4 Issue 2 (February 2016

Improved high-frequency carrier voltage measurement for position estimation of switched-flux permanent magnet machines

The conventional 12/10 stator/rotor poles switched-flux permanent magnet (SFPM) machine is usually based on all poles wound topology, each phase comprising four winding coils in series connection. However, alternate coils of the same phase have different machine saliency characteristics. Moreover, in order to measure the high-frequency (HF) carrier voltage, the mid-tapered winding wires can be utilized. Consequently, the machine saliencies can be measured separately from two parts of winding coil connections. This paper investigates the influences of machine saliencies on the sensorless rotor position estimations based on different sequence of winding coil connections, in which the primary saliency may contain some additional harmonics referring to the secondary saliency that will degrade the overall sensorless control operations. Furthermore, a simple compensation method is proposed to reduce the influence of multiple saliencies to achieve more accurate sensorless rotor position estimation. By comparing with rotor positon estimations without the proposed compensation and HF carrier current based method, the effectiveness of improved sensorless rotor position estimation has been demonstrated experimentally, as well as the application to dual 3-phase SFPM machines