Injection-based Sensorless Control Research Articles

An Improved High-Frequency Voltage Signal Injection-Based Sensorless Control of IPMSM Drives With Current Observer

An Improved High-Frequency Voltage Signal Injection-Based Sensorless Control of IPMSM Drives With Current Observer

A High-Frequency Signal Injection-Based Sensorless Control Method Robust to Single and Double Open-Phase Faults for a Dual Three-Phase Motor

A High-Frequency Signal Injection-Based Sensorless Control Method Robust to Single and Double Open-Phase Faults for a Dual Three-Phase Motor

Novel Random High-Frequency Square-Wave and Pulse Voltage Injection Scheme-Based Sensorless Control of IPMSM Drives

Signal injection-based sensorless control schemes for interior permanent magnet synchronous machine (IPMSM) drives at zero and low speed are generally troubled by the audible noise induced by the fixed-frequency injected signals and the control performance sensitive to voltage distortions. Aiming at that, a novel random high-frequency square-wave and pulse voltage injection (RHFSPVI) with novel signal demodulation method-based sensorless control of IPMSM drives is proposed. First, the power spectra density (PSD) analyses of conventional high-frequency square-wave voltage injection (HFSVI) and high-frequency pulse voltage injection (HFPVI) methods are carried out. On the basis of the analysis results, the simple form of random square-wave and pulse voltage injection is analyzed and designed to eliminate discrete harmonics in the current PSD spectrum for the audible noise reduction. Moreover, a signal demodulation scheme matched with the proposed injected form is designed to prevent the impact of voltage distortions on the position estimation accuracy. The capability of the proposed sensorless control scheme is verified on a 750-W IPMSM drive platform.

Position Estimation Accuracy Improvement for SPMSM Sensorless Drives by Adaptive Complex-Coefficient Filter and DPLL

This paper presents an improved high-frequency pulsating square-wave signal injection-based sensorless control for surface-mounted permanent-magnet synchronous machines (SPMSM). The use of low pass filter in the traditional sensorless method results in phase delay and, consequently, degrades the dynamic behavior. In order to eliminate such drawback, the proposed method adopts an adaptive complex-coefficient filter (ACCF) that does not cause phase delay and the use of compensation technique is avoided. Moreover, a dual-phase-locked loop (DPLL) is utilized to extract the accurate rotor position and eliminates the position estimation error in dynamic state. The small signal model of ACCF is build, and then the unified parameter selection guideline for both ACCF and DPLL is given in terms of comprehensive transfer function analysis. The proposed method has been carried out by both simulation and experiment, where a Higale platform with a 0.2-kW SPMSM is adopted to verify the performance of proposed method.

Adaptive Pseudorandom High-Frequency Square-Wave Voltage Injection Based Sensorless Control for SynRM Drives

The remarkable inductance nonlinearities of synchronous reluctance motors (SynRMs) could result in operating-point-dependent high-frequency (HF) current responses, and more HF losses with audible noises with conventional constant amplitude high-frequency signal injection (HFSI) methods applied. This article proposes an adaptive pseudorandom high-frequency square-wave voltage injection (AP-HFSVI) based sensorless control method for SynRM drives at low-speed operation. An adaptive HF current control strategy is applied using pseudorandom injection patterns to adapt to the nonlinear characteristic of SynRM inductances. The magnitude of the injected HF voltage signals can be adjusted adaptively with the load variation online via HF current adaptive control scheme, which processes and regulates the HF current components to be constant. Hence, the HF losses and audible noises can be effectively suppressed due to the decreasing magnitude of injected signals. The current power spectra density of the AP-HFSVI method is analyzed and compared with the conventional HFSI method. The effectiveness and superiority of the proposed sensorless control method are verified with experiments on a 3-kW SynRM drive platform.

Self-Adaptive High-Frequency Injection Based Sensorless Control for Interior Permanent Magnet Synchronous Motor Drives

An auto-tuning and self-adaptation procedure for High Frequency Injection (HFI) based position and speed estimation algorithms in Interior Permanent Magnet Synchronous Motor (IPMSM) drives is proposed in this paper. Analytical developments show that, using conventional approaches, the dynamics of the high-frequency tracking loop varies with differential inductances, which in turn depend on the machine operating point. On-line estimation and adaptation of the small signal gain of the loop is proposed here, allowing accurate auto-tuning of the sensorless control scheme which does not rely on a priori knowledge of the machine parameters. On-line adaptation of Phase-Locked Loop (PLL) gains and of the injected voltage magnitude is also possible, leading to important advantages from the performance, loss and acoustic point of view. The theoretical basis of the method has been introduced first and the main concept demonstrated by means of simulations. Implementation has been carried out using the hardware of a commercial industrial drive and two Interior Permanent Magnet Synchronous Motors, namely a prototype and an off-the-shelf machine. Experimental tests demonstrate the feasibility and effectiveness of the proposal.

High-Frequency Injection-Based Sensorless Control for a General Five-Phase BLDC Motor Incorporating System Delay and Phase Resistance

This paper investigates the sensorless control of a general Five-phase permanent magnet brushless DC (5Φ-BLDC) motor working at the low speeds. High frequency (HF) injection-based sensorless control is most popular, however, the system delay and stator resistance could deteriorate the sensorless control performance. In this paper, an HF model of 5Φ BLDCs at frequency-domain is primarily established as a replacement over the conventional static model, and an interpretation from the sinusoidal internal model is carried out to direct the sensorless control implementation. Accordingly, the measured d-axis HF current, which is typically neglected in the conventional method, is reused to demodulate the position angular information from the measured q-axis HF current. The proposed sensorless control is performed on a 5Φ BLDC drive, and experimental results confirm the effectiveness of this method while comparing its performance with the conventional method.

Sensorless Control for Permanent Magnet Synchronous Motor in Rail Transit Application Using Segmented Synchronous Modulation

This paper proposes a position sensorless control technique for permanent magnet synchronous motor (PMSM) used in rail transit application, where a segmented synchronous modulation (SSM) is usually applied. The arbitrary signal injection-based sensorless control is adopted to estimate rotor position. In a switching period, an oversampling technique is used to obtain the average current slope that contains the rotor position information during the active voltage-vector operation. In SSM, the hysteresis zone is set near the carrier ratio (CR) switching critical point to eliminate the influence of the repeated oscillation on the current measurement accuracy. Furthermore, a load disturbance compensation method is designed so that the failure of hysteresis zone is avoided. Through the analysis of power spectral density (PSD) of phase current, the optimization of harmonic energy distribution with hysteresis zone is also verified. The experimental results show that the proposed method can improve the position estimation precision during the fast CR transition, which can be effectively applied in SSM.

Comparative Investigation of Pseudorandom High-Frequency Signal Injection Schemes for Sensorless IPMSM Drives

The fixed-frequency signal is employed in conventional high-frequency (HF) signal injection-based sensorless control schemes for interior permanent magnet synchronous motor (IPMSM) drives, which causes significant electromagnetic and acoustic noises. In order to diminish the additional noises, a novel pseudorandom HF (PRHF) signal injection method is investigated in this paper. Comparative analysis of the power spectra density of the induced HF currents is carried out among three different schemes: fixed-frequency HF, full-period-switch (FPS) PRHF, and half-period-switch (HPS) PRHF square-wave voltage injection. The principles and the spectral characteristics of the three PRHF injection schemes are described. Both theoretical analysis and experimental results are provided, which can agree with each other well. A theoretical basis of frequency determination is presented. Comparison of the spectral performance shows that the HPS–PRHF scheme has continuous spectra and the electromagnetic and acoustic noises can be suppressed significantly. The method is verified via a 2.2-kW IPMSM drive platform.

Pseudo-Random High-Frequency Square-Wave Voltage Injection Based Sensorless Control of IPMSM Drives for Audible Noise Reduction

High frequency (HF) signal injection is an effective sensorless control scheme for interior permanent-magnet synchronous motor (IPMSM) drives to achieve low and zero speed operation. However, the audible noise produced by the injected HF signal is often very shrill and harsh to hear, which restricts the actual application. In order to reduce the audible noise, a novel pseudo-random HF square-wave voltage injection scheme is proposed in this paper. The HF voltages with two different frequencies are randomly injected into the estimated rotor reference frame cycle by cycle, and a corresponding signal demodulation method for extracting the rotor position information is presented. Based on the principle analysis of this random frequency injection scheme, the digital time-delay effect in HF signal is considered and a compensation method for signal demodulation is proposed, which is effective in reducing position estimation error. Then, the power spectra density (PSD) in fixed frequency and pseudo-random frequency injection schemes are compared both theoretically and experimentally. The distribution of HF voltage and current PSD is extended by using the proposed injection scheme. Finally, this sensorless control method is verified by simulation and experiment on a 2.2-kW IPMSM drive platform.

Carrier Signal Injection-Based Sensorless Control for Permanent-Magnet Synchronous Machine Drives Considering Machine Parameter Asymmetry

This paper investigates the influence of asymmetric machine parameters on carrier signal injection-based sensorless control of permanent-magnet synchronous machines (PMSMs). With either rotating or pulsating signal injection, the second harmonic position errors arise due to the parameter asymmetry. Furthermore, it is found that for the two carriers, the second harmonic errors are different for resistance asymmetry but the same for inductance asymmetry. In order to suppress the position errors, the carrier signal selection guidelines are discussed for resistance asymmetry, while for inductance asymmetry, novel online compensation strategies with dual-frequency injection are also proposed. Finally, the theoretical analyses and proposed compensation methods are validated by experiments on an interior PM (IPM) machine with added phase resistance/inductance to simulate asymmetric conditions.

Impact of Rotor Design on Interior Permanent-Magnet Machines With Concentrated and Distributed Windings for Signal Injection-Based Sensorless Control and Power Conversion

This paper examines the relationship between rotor design, saliency-based signal injection sensorless control, and power conversion properties for four industrially relevant interior permanent-magnet machine configurations: a 36-slot 6-pole stator with v bar rotor, a 36-slot 6-pole stator with flat bar rotor, a 9-slot 6-pole stator with v bar rotor, and a 9-slot 6-pole stator with flat bar rotor. The influence of rotor geometric design variables over the range of current densities at the maximum torque per ampere angle was found using a design of experiments' methodology and standardized regression coefficients. Tradeoffs between sensorless control and power conversion properties are found using a Monte Carlo methodology. Power conversion and sensorless control properties were analyzed using hybrid static and time-stepping finite-element simulations.

Investigation of Saliency in a Switched-Flux Permanent-Magnet Machine Using High-Frequency Signal Injection

In order to facilitate the selection of machine whether it is suitable for high-frequency (HF)-signal injection-based sensorless control or not, this paper proposes a complete experimental investigation method for the analysis and validation of machine saliency level, including primary saliency, which is essential for HF injection-based sensorless control, and the secondary saliency, which will deteriorate the rotor-position estimation. The experimental results obtained on a new type of switched-flux permanent-magnet (SFPM) machine prove that with identified primary saliency, the accurate rotor-position estimation can be achieved, and with small secondary saliency, the estimation will not be deteriorated much in the SFPM machine. The conclusion is verified by the experiments based on the HF pulsating signal injection-based sensorless control at zero and low speeds.

Performance of Pulsating High-Frequency Current Injection Based Sensorless Control of PMSM

In the paper the principle and performances of the pulsating current injection based sensorless control of permanent magnet synchronous motor (PMSM) are analyzed theoretically and investigated by simulations. In the analyses, the effects of the speed EMF terms and the deviation between the actual d-axis high-frequency current and the command, which results from the limited gain and bandwidth of the current control loop, are all taken into account. It is shown that the pulsating current injection method can achieve stable position estimation in a wide speed range. But appreciable position errors will result at high speeds due to the cross-coupling effects of the speed EMFs and the tracking error between the actual and command carrier current. In order to improve the performance, a modified scheme is proposed. Its validity is confirmed by simulations.

A Wavelet Filtering Scheme for Noise and Vibration Reduction in High-frequency Signal Injection-Based Sensorless Control of PMSM at Low Speed

This paper presents a technique for noise and vibration reduction in low-speed sensorless control algorithm of surface mounted permanent magnet synchronous machines (SM-PMSM). The signal processing involved in high-frequency-based sensorless control algorithms has a significant effect on the vibration and noise accompanying such algorithms. Therefore, a wavelet filtering approach is proposed. This wavelet filter is capable of extracting the position information even at low values of injection voltage amplitude where conventional filters fail to extract the information. This leads to a reduction in the machine's noise and vibration. Furthermore, an optimization using hardware-in-the-loop method based on genetic algorithms was implemented in real time to obtain the optimum value of the injected voltages amplitude and frequency causing the least possible vibration with acceptable position estimation accuracy. Consequently, a significant reduction in vibration and noise was achieved. The proposed techniques were implemented on a 2-hp SM-PMSM motor both experimentally and through simulations. Comparisons between numerical and test results confirm the validity of the proposed techniques.

Analysis of Stator Resistance Effects in Carrier Signal Injection Based Sensorless Control of Permanent Magnet Synchronous Machine

This paper analyzes the effects of stator resistance on rotor position estimation accuracy in carrier signal injection based sensorless control of PMSM. Carrier current expressions are derived for both rotating and pulsating voltage injection method when the stator resistance is taken into account. Position estimation errors resulted from stator resistance are analyzed theoretically and investigated by simulation. It is shown that the influences of stator resistance on above two injection methods are quite different. The stator resistance will result in a position estimation error in the rotating voltage injection method. But it does not affect the position estimation accuracy in the pulsating voltage injection method as long as a suitable signal extracting method is used.

A Novel Method for Compensating Inverter Nonlinearity Effects in Carrier Signal Injection-Based Sensorless Control From Positive-Sequence Carrier Current Distortion

In conventional rotating carrier signal injection-based sensorless method, a positive-sequence carrier current has no use, and only the negative-sequence carrier current is used to estimate the rotor position information. The inverter nonlinearity effects, however, distort the negative-sequence carrier current and result in inaccurate position estimation. With the aid of theoretical analysis and experimental measurement, it is proven in this paper that the positive-sequence carrier current distortion resulting from inverter nonlinearity effects can be used to compensate the influence of inverter nonlinearity on negative-sequence carrier current. Hence, a new online postcompensation scheme is developed in this paper by utilizing the distortion of positive-sequence carrier current due to inverter nonlinearity effects. The proposed method can be easily implemented on standard voltage source inverter without any offline commissioning process or hardware modification. Experimental results confirm the effectiveness of the proposed method in suppressing the influence of inverter nonlinearity on the rotor position estimation.

Measuring, modeling, and decoupling of saturation-induced saliencies in carrier-signal injection-based sensorless AC drives

The focus of this paper is the measuring, modeling, and decoupling of saturation-induced saliencies in carrier-signal injection-based sensorless control. First, techniques for the measurement of saturation-induced saliencies are presented. The goal of these measurements is to provide useful information on the position and magnitude of the various saturation-induced saliencies. Using the results from several different experimental measurements, models are developed explaining the source and behavior of the saturation-induced saliencies. The paper concludes by presenting methods for decoupling the effects caused by the parasitic saturation-induced saliencies, eliminating the errors that they cause in rotor position or flux angle estimation.