High Frequency Signal Injection Technique Research Articles

Novel Compensation Method to Reduce Rotor Position Estimation Error and Torque Reduction in Signal Injection Based PMSM Drives

High frequency signal injection techniques are widely used to extract rotor position information from low speed to stand still. Accuracy of estimated rotor position is decreased when stator winding resistance is neglected. Position estimation error also results in output Torque reduction. Parasitic resistance of stator winding causes significant position estimation error <br /> and Torque reduction, if not compensated. Signal injection techniques developed in the literature does not provide detailed analysis and compensation methods to improve rotor position estimation of PMS Motors, where stator winding resistance cannot be neglected. This work analyzes the stator winding resistance effect on position estimation accuracy and proposes novel compensation technique to reduce the position estimation error and torque reduction introduced by stator winding resistance. Prototype hardware of a self-sensing PMSM drive is developed. The effectiveness of the proposed method is verified with the MATLAB/Simulink simulations and experimental results on a prototype self-sensing PMSM drive.

High-Frequency-Injection-Assisted “Active-Flux”-Based Sensorless Vector Control of Reluctance Synchronous Motors, With Experiments From Zero Speed

This paper presents a hybrid motion sensorless control of an axially laminated anisotropic reluctance synchronous machine (RSM). The zero- and low-speed sensorless method is a saliency-based high-frequency signal injection technique that uses the motor itself as a resolver. The second method is based on a state observer incorporating the “active-flux” concept used to deliver RSM rotor position and speed information for medium- and high-speed range. Even if both methods perform successfully in separate speed regions, estimation of the two algorithms is combined as a sensor fusion to improve the performance at zero and very low speeds. Experimental results validate the proposed control strategies.

Optimized High Frequency Signal Injection Based Permanent Magnet Synchronous Motor Rotor Position Estimation Applied to Washing Machines

Problem statement: This study investigates a novel optimized scheme of a High Frequency Signal Injection (HFSI) based sensor less technique in order to carry out a precise and robust rotor position error estimation of a Permanent Magnet Synchronous Motor (PMSM) drive designed for washing machines. The study was carried out for standstill condition, where precise position information was required for this application. Approach: In order to get rotor position error information, a PMSM high frequency model was considered in the estimated rotor reference frame (d,q). The impact of the HFSI technique parameters choice on the PMSM rotor position estimation performance was studied and experimentally tested, under various injection conditions. Results: The experimental results show that the amplitude of the high frequency current, resulting from injection, was not significant to carry out high performance rotor position estimation. In order to improve rotor position estimation performance and robustness, a modified demodulation of the high frequency current resulting from injection was proposed by using a high pass filter amplifier applied to PMSM measured currents. The novel proposed rotor position error extraction scheme was implemented on a dsPIC30F6010A and was experimentally validated on a 1kW washing salient pole PMSM. Conclusion: This study presents an improved high frequency voltage injection based sensor less control for Permanent Magnet Synchronous Motor (PMSM) designed for washing machines. The optimal parameters choice of the HFSI technique and the use of a high pass filter amplifier have allowed to take the most of the high frequency injected signal for extracting the rotor position error at standstill, compared to a conventional scheme.

Sensorless Control of IPM Motors in the Low-Speed Range and at Standstill by HF Injection and DFT Processing

In this paper, a sensorless controller for an interior permanent-magnet synchronous motor is presented based on well-known high-frequency signal injection techniques. The issue of the demodulation process is the key point of this paper. A novel approach based on discrete Fourier transform and nonconventional reference frame transformation is presented, allowing a simple and robust noncoherent demodulation, i.e., in which no information about the carrier phase is needed. In the classically adopted coherent approaches, in fact, uncertainty about carrier phase reflects in uncertainty in the demodulated signal amplitude, affecting observer gains and signal-to-noise ratio and definitively providing a degradation of the performance of the estimator. Analytical development of the sensorless algorithm, including the demodulation technique, is provided. A complete investigation by simulation is carried out aiming at showing the performance of the proposed method. Finally, experimental results are presented based on a prototype motor drive for city scooters.

Determination of High-Frequency $d$- and $q$-axis Inductances for Surface-Mounted Permanent-Magnet Synchronous Machines

This paper presents a reliable method for the experimental determination of high-frequency d- and q -axis inductances for surface-mounted permanent-magnet synchronous machines (SMPMSMs). Knowledge of the high-frequency d- and q-axis inductances plays an important role in the efficient design of sensorless controllers using high-frequency signal injection techniques. The proposed method employs a static locked-rotor test using an ac +dc power supply. By injecting a high-frequency rotating voltage vector into the machine, the d- and q-axis inductances may simultaneously be determined with no need to change the rotor position. Measurements are carried out at steady state. The recording of instantaneous waveforms using a dedicated data acquisition system is avoided. In this paper, experimental results are presented, on a commercial SMPMSM, using the proposed method.

Low-Speed and Standstill Operation of a Sensorless Direct Torque and Flux Controlled IPM Synchronous Motor Drive

This paper investigates a sensorless direct torque and flux control scheme for interior permanent magnet synchronous motor drives at low speeds, including standstill. Closed-loop control of both torque and stator flux linkage are achieved by using two proportional-integral controllers. The reference voltage vectors are generated by a space vector modulation unit. A high-frequency signal injection technique is adopted at low speeds to obtain the rotor position information. A hybrid current-voltage model flux observer with a smooth handover algorithm estimates the stator flux linkage over the whole speed range. Experimental results confirm the effectiveness of the proposed method.

Sensorless direct torque and flux control of an IPM synchronous motor drive at low speed and standstill

This paper investigates a sensorless direct torque and flux control (DTFC) scheme for interior permanent magnet synchronous motor (IPMSM) drives at low speed and standstill. Closed-loop control of both the torque and stator flux linkage are achieved using two proportional-integral (PI) controllers. A high frequency signal injection technique is utilised at low speeds to obtain the rotor position information. The hybrid current-voltage model flux observer with a smooth handover algorithm estimates the stator flux linkage over the whole speed range. The sensorless method is capable of zero-speed full load operation. Experimental results confirm the effectiveness of the proposed sensorless space vector modulation-DTFC system.

Sensorless Direct Torque and Flux Controlled Interior Permanent Magnet Synchronous Motor Drive Over a Wide Speed Range

This paper investigates a sensorless direct torque and flux control (DTFC) scheme based on space vector modulation (SVM) for interior permanent magnet synchronous motor (IPMSM) drives over a wide speed range. Closed-loop control of both the torque and stator flux linkage are achieved by using two proportional-integral (PI) controllers. The reference voltage vectors are generated by a SVM unit. A high frequency signal injection technique is adopted at low speeds to obtain the rotor position information. The hybrid current-voltage model flux observer with a smooth handover algorithm estimates the stator flux linkage over the whole speed range. The operating range of the sensorless DTFC drive is extended into the high speed region by incorporating field weakening. Experimental results confirm the effectiveness of the proposed method.

Adaptation of Motor Parameters in Sensorless PMSM Drives

This paper proposes an online method for the estimation of the stator resistance and the permanent-magnet (PM) flux in sensorless PM synchronous motor drives. An adaptive observer augmented with a high-frequency signal injection technique is used for sensorless control. The observer contains excess information that is not used for the speed and position estimation. This information is used for the adaptation of the motor parameters: At low speeds, the stator resistance is estimated, whereas at medium and high speeds, the PM flux is estimated. Small-signal analysis is carried out to investigate the proposed method. The convergence of the parameter estimates is shown by simulations and laboratory experiments. The stator resistance adaptation works down to zero speed in sensorless control.

Implementation Issues in Voltage Zero Sequence-Based Encoderless Techniques

Recent articles demonstrate that sensorless drives for induction motors can operate at zero-electrical and mechanical frequencies with the aid of high-frequency signal injection techniques and processing the zero-sequence voltage signals. The paper presents some practical implementation issues affecting the performance of such a technique and shows how to improve the quality of the estimated angle. All the assessments are experimentally proved and have a general value that can be extended to other sensorless techniques injecting high-frequency signal.