Sensorless Control Of Interior Permanent Magnet Synchronous Motor Research Articles

Enhanced Linear ADRC Strategy for Sensorless Control of IPMSM Considering Cross-Coupling Factors

Estimation of rotor coordinate system by high-frequency (HF) signal injection is an effective sensorless control strategy, which can solve the decoupling problem of position information of interior permanent magnet synchronous motor (IPMSM) in the low-speed range. However, the inductance cross-coupling phenomenon caused by magnetic saturation will lead to a decline in the accuracy of rotor angle extraction, resulting in a serious deterioration of the sensorless control performance. To solve this problem, an HF signal injection method considering <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d-q</i> axis coupling inductance is proposed to estimate HF inductance and the rotor angle. The estimated HF inductor combined with the current loop enhanced linear active disturbance rejection control (ELADRC) is used in the current loop control to estimate the disturbance and improve the current regulation quality of the current control system. Furthermore, the stability and the tracking performance of the enhanced LADRC are analyzed theoretically. Finally, the stability of a closed-loop IPMSM drives system based on ELADRC considering HF inductance is analyzed. The experimental results of a salient pole IPMSMs driver verify the effectiveness and practicability of the scheme.

Sensorless Control of IPMSM Drives Using High-Frequency Pulse Voltage Injection With Random Pulse Sequence for Audible Noise Reduction

Saliency tracking based sensorless control schemes of interior permanent magnet synchronous motor (IPMSM) are generally troubled by the audible noise induced by high-frequency (HF) signal injection and the estimation error caused by voltage distortions. Aiming at that, a novel sensorless control strategy of IPMSM drives using HF pulse voltage injection with random pulse sequence (HFPVI-RPS) is proposed. Firstly, the conventional HFPVI method could restrain the impact of voltage distortions, and its mechanism is briefly reviewed. Then, based on that, a novel injected form that injecting HF pulse signals with random pulse sequence into the estimated d-axis is designed to eliminate discrete harmonics in the current power spectra density (PSD) and broaden the current PSD to a wide range. The audible noise can be reduced as much as possible. Further, a signal demodulation scheme matched with the injected form of HFPVI-RPS is proposed for the accurate extraction of rotor position. The PSD analysis of the HFPVI and proposed HFPVI-RPS methods is carried out, and the PSD comparison between reported methods and HFPVI-RPS method is given. Eventually, the effectiveness of the proposed sensorless control strategy is verified on a 750W IPMSM drive platform.

Ripple Excitation-Based Adaptive Sensorless Control of IPMSM in Full Speed Range

This paper proposes an adaptive sensorless finite-control-set model predictive control (FCS-MPC) method for the interior permanent magnet synchronous motor (IPMSM). The method is feasible in the full speed range from zero speed to the flux-weakening region above rated speed, without the method transition between the low and the high speeds. A ripple excitation-based position estimation method is proposed to extract the rotor-saliency-based position information from the inherent voltage ripples of the FCS-MPC. Therefore, the additional voltage margin consumption, the special sampling timing, or the interference in the fundamental control are all avoided. Furthermore, to alleviate the parameter dependency, an adaptive predictive model with the online estimation of the lumped voltage terms and the equivalent dynamic susceptances is proposed. In this way, the main machine parameters and the unmodeled disturbances in the d-q voltage equations of the IPMSM are all considered. The position deviation due to the cross-coupling effect is also analyzed, and a compensation method is proposed. Finally, the effectiveness of the proposed method is validated by the experimental results and the comparison with existing methods.

Sensorless control of IPMSM using a discrete-time super twisting observer by high-frequency current injection in low speed region

Control of interior permanent magnet synchronous motors (IPMSMs) has been extensively attempted without any position sensor. At extremely low speeds, sensorless operation would not rely on the fundamental model-based sensorless methods since the situation becomes more sophisticated. The existing high-frequency (HF) injection techniques predominantly concentrate on current or voltage excitations. Whereas, compromises are made between the signal strength and inevitably generated current fluctuations and torque ripples. Noise and disturbances could also deteriorate the performance. To accomplish the low speed sensorless operation successfully, this paper presents a position error observer and a current injection scheme for the extremely low speed sensorless operation. A discrete-time super twisting extended-state observer (STESO) extracts the estimated position and speed considering the disturbances. The design of the HF observer is carried out. The lowest speed is extended down to 2% rated value in the experimental tests.

Special‐angle‐based signal injection sensorless control of IPMSM for suppressing multiple zero‐crossings of phase current

Pulsating high-frequency signal injection has the problem of multiple zero-crossings when the phase current crosses zero-point, which deteriorates the distortion of high-frequency current caused by the zero-current-clamping effect. Thus, the accuracy of position observation is affected. To suppress multiple zero-crossings, improved sinusoidal and square-wave signal injection schemes are proposed. First, the relationship between the injection angle of the high-frequency signal and the phase of the high-frequency response current amplitude function is analysed. Based on the relationship, a special injection angle is calculated. By injecting the pulsating signal in the obtained special angle, the phase of the high-frequency current is shifted. The amplitude of the high-frequency response current is minimum when the fundamental frequency current crosses zero, thus reducing zero-crossing points of phase current. Furthermore, the error signal extraction scheme applicable to arbitrary angle injection is designed to observe rotor position. The proposed high-frequency signal injection method minimises the zero-crossings of the phase current at any value of the torque angle. Both of the novel sinusoidal pulsating injection sensorless control scheme and square-wave injection sensorless control scheme are confirmed by experiments on a 2.2-kW interior permanent magnet synchronous motor (IPMSM) drive platform.

Sensorless Control of IPMSM Based on Super-Twisting Sliding Mode Observer With CVGI Considering Flying Start

In this article, a super-twisting algorithm-based sliding mode observer (STA-SMO) with a complex vector generalized integrator (CVGI) for sensorless control of an interior permanent magnet synchronous motor (IPMSM) is proposed. The STA-SMO exists the compromise between chattering and estimation accuracy under limited control frequency in practice. In order to solve this problem, a CVGI is introduced to guarantee the accuracy of the back electromotive force (EMF) estimation while alleviating chattering. The proposed STA-SMO with CVGI can be used not only in the normal operation but also in the flying start operation based on virtual resistance. The accuracy of the estimated rotor position is not influenced by the value of the virtual resistance during flying start. Furthermore, the proposed STA-SMO with CVGI is designed based on the discrete model of the IPMSM in the discrete-time domain. The stability of the proposed method in the discrete-time domain is further analyzed. Finally, the effectiveness of proposed method is verified by experiments.

A new Bernard–Praly-like observer for sensorless IPMSMs

A slight extension of the global Bernard–Praly gradient adaptive observer – originally presented for nonsalient-pole surface Permanent Magnet Synchronous Motors (PMSMs) and recently proved to own local exponential convergence properties under well-known observability conditions – is here designed and proposed for Interior Permanent Magnet Synchronous Motors (IPMSMs) (with relatively small saliency) in the case in which the q-axis current is constant. It guarantees local exponential estimation – from stator current and voltage measurements – of both the stator fluxes and the sinusoidal/co-sinusoidal functions of the motor electrical angle, with no modification of the previous persistency of excitation condition requirements. Such an extension complements – at least locally – a previous analysis concerning IPMSMs under constant d-axis current. Applications to the sensorless control of IPMSMs (with realistic simulations) are included.

IPMSM Sensorless Control for Zero- and Low-Speed Regions Under Low Switching Frequency Condition Based on Fundamental Model

In the high-power traction system, such as rail transit, the switching frequency is relatively low. The bandwidth of the current controller and the frequency of the injected signal are both limited under low switching frequency, which hinders the sensorless control of interior permanent magnet synchronous motor (IPMSM) in the zero- and low-speed regions. This article presents an IPMSM sensorless control for zero- and low-speed regions under low switching frequency conditions based on the fundamental model. The position can be estimated from the estimated virtual back electromotive force (EMF) with sinusoidal current injection. An internal model control (IMC) and a vector PI (VPI) control are designed to solve the problem of current controller bandwidth limitation. The multiple adaptive filters (AFs) based on the second-order second-order generalized integrator (SO-SOGI) are designed to eliminate the harmonics related to the injection frequency and the fundamental frequency in the stationary frame (SF) to improve the control performance. Meanwhile, the proposed sensorless control strategy is extended from the SF to the rotating frame (RF), which is easier to implement. The rotor position and speed are estimated by a third-order supertwisting extended state observer. The effectiveness of both proposed strategies is verified by experiments.

An Improved Sensorless Control of IPMSM Based On Pulsating High-Frequency Signal Injection With Less Filtering for Rail Transit Applications

A pulsating high-frequency signal injection-based low-speed sensorless control of interior permanent magnet synchronous motor (IPMSM) using a conventional stationary reference frame low-pass filter (LPF) may experience a phase delay. Similarly, the heterodyning process may exhibit time delay and bandwidth restriction. Thus, an improved approach with a single high-pass filter in a stationary reference frame is proposed. The rotor position error is extracted from the high-frequency current using the sign of sine of the injected signal considering the phase shift. Consequently, the estimated reference frame LPF in the heterodyning process and the delay compensator for a stationary reference frame LPF-based approach are discarded. A phase-shift tracking observer (PSTO) independent of position error is included. Meanwhile, an online d-axis high-frequency current amplitude estimation is adopted to normalize the effect of d-axis inductance variation. The comparative study with a stationary reference frame LPF and the heterodyning process has shown that the proposed self-sensing strategy delivers an excellent speed sensorless control performance. Thanks to the online d-axis current amplitude estimation, the impact of d-axis inductance variation on speed-position identification has been improved. The proposed self-sensing strategy has been validated using MATLAB simulation and Hardware-in-the-loop (HIL) with TMS320F28335 digital signal processor considering rail transit applications.

A Novel Strategy for Sensorless Control of IPMSM with Error Compensation Based on Rotating High Frequency Carrier Signal Injection

In the applications of rail transit and electric vehicles, sensorless control of interior permanent magnet synchronous motor (IPMSM) usually uses high frequency (HF) signal injection in low speed or zero speed. Rotating HF signal injection based on the stationary reference frame can identify the rotor position, but its accuracy is easily affected by various nonlinearities of the control system and stator resistance. In this paper, the causes of rotor position estimation deviation are analyzed and deduced in detail. It is proposed that the rotor position estimation deviation can be divided into high frequency phase deviation (HFPD) and stator resistance phase deviation. On the basis of these analyses, a novel sensorless rotor position estimation strategy for IPMSM is proposed. This strategy can theoretically eliminate the HF phase deviation caused by the nonlinearity of the control system and reduce the phase deviation caused by the stator resistance. Although the factors that cause the estimation deviation of rotor position may change with the time and the operation status of the motor, the proposed strategy has the characteristics of online calculation and real-time compensation, which can improve the accuracy of the estimated rotor position. In addition, this paper provides a detailed theoretical derivation of resolving rotor position considering stator resistance and HF phase deviation. Finally, the result analysis on an IPMSM demonstrate the correctness of the theoretical analysis and the effectiveness of the strategy.

High Frequency Square-Wave Voltage Injection Scheme-Based Position Sensorless Control of IPMSM in the Low- and Zero- Speed Range

In this paper, a new sensorless control scheme with the injection of a high-frequency square-wave voltage of an interior permanent-magnet synchronous motor (IPMSM) at low- and zero-speed operation is proposed. Conventional schemes may face the problems of obvious current sampling noise and slow identification in the process of magnetic polarity detection at zero speed operation, and the effects of inverter voltage error on the rotor position estimation accuracy at low speed operation. Based on the principle analysis of d-axis magnetic circuit characteristics, a method for determining the direction of magnetic polarity of d-axis two-opposite DC voltage offset by uninterruptible square-wave injection is proposed, which is fast in convergence rate of magnetic polarity detection and more distinct. In addition, the strategy injects a two-opposite high-frequency square-wave voltage vectors other than the one voltage vector into the estimated synchronous reference frame (SRF), which can reduce the effects of inverter voltage error on the rotor position estimation accuracy. With this approach, low-pass filter (LPF) and band-pass filter (BPF), which are used to obtain the fundamental current component and high-frequency current response with rotor position information respectively in the conventional sensorless control, are removed to simplify the signal process for estimating the rotor position and further improve control bandwidth. Finally, the experimental results on an IPMSM drive platform indicate that the rotor position with good steady state and dynamic performance can be obtained accurately at low-and zero-speed operation with the sensorless control strategy.

Noise Spectrum Shaping of Random High-Frequency-Voltage Injection Based on Markov Chain for IPMSM Sensorless Control

The high-frequency (HF) voltage injection method can accurately estimate the rotor position of an interior permanent magnet synchronous motor (IPMSM) at low speed and zero speed. However, the fixed injection frequency for the traditional HF-voltage injection method will produce loud audible noise. The random HF-voltage injection method has a spread spectrum, which can reduce the audible noise. However, random HF voltages are controlled by constant probability rules, and it is inevitable that continuous multiple random numbers are larger or smaller than the mathematical expectation in the digital implementation, which will lead to spectrum concentration of the HF current. Thus, the random HF-voltage injection method cannot reduce the audible noise effectively. A novel random HF square-wave voltage injection method for an IPMSM based on the Markov chain (MC) is proposed to reduce the audible noise. The transition of the injected HF square-wave voltages obeys the MC instead of constant probability rules, which not only can shape the power spectrum of the HF current but also enable the explicit control of the HF current time-domain performance to reduce the audible noise. In order to reduce the position error caused by the phase mismatch between the HF current and the demodulation signal, an enhanced signal processing method is presented. Then, the power spectra density of the proposed method is analyzed to verify the effectiveness. Finally, the correctness and the effectiveness of the proposed method are verified by experiment on a 2.0-kW IPMSM drive platform.

Enhanced Position Sensorless Control Using Bilinear Recursive Least Squares Adaptive Filter for Interior Permanent Magnet Synchronous Motor

In the back electromotive force (EMF)-based sensorless control of interior permanent magnet synchronous motor (IPMSM), the inverter nonlinearity and flux linkage spatial harmonics will possibly give rise to (6k ± 1)th harmonics in the estimated back EMF, especially the fifth and seventh harmonics. Those harmonics will consequently introduce (6k)th harmonic ripples to the estimated rotor position, especially the sixth harmonic component. In order to solve this problem, a bilinear recursive least squares (BRLS) adaptive filter is proposed and integrated into a sliding-mode position observer to suppress the dominant harmonic components in the estimated back EMF and as a result, the accuracy of the estimated rotor position can be greatly improved. A unique feature of the BRLS adaptive filter is its ability to track and suppress the specified harmonic components in different steady state and dynamic operational conditions. The proposed method can compensate for harmonic ripples caused by the inverter nonlinearity and machine spatial harmonics at the same time; this method is also robust to machine parameter variation, and the BRLS algorithm itself is machine parameter independent. The implementation of the proposed BRLS filter in the sensorless control of IPMSM is explained in details in this paper. The enhanced drive performances using the BRLS filter have been thoroughly validated in different steady state and dynamic operational conditions on a 1.5-kW IPMSM sensorless drive.

A Combining FPE and Additional Test Vectors Hybrid Strategy for IPMSM Sensorless Control

This paper proposes a hybrid strategy by combining fundamental pulsewidth modulation excitation (FPE) and additional test vectors, which is used in interior permanent-magnet synchronous motor (IPMSM) sensorless control. In contrast to the typical indirect flux detection by on-line reactance measurement-based methodology where the rotor position is calculated and updated in every three successive pulsewidth modulation (PWM) cycles, the proposed hybrid strategy can achieve the one-cycle acquisition of the rotor position by utilizing both response currents of FPE and additional test vectors, which makes the proposed strategy more robust and suitable in higher speed or load sudden change conditions. Meanwhile, a new PWM scheme for four-space-vector PWM (FSVPWM) is presented, which sharply simplifies the implementation process. Furthermore, for the case that the amplitude of the object fundamental voltage is so small that it cannot satisfy minimum time demand for the slopes of response currents sampling, a compensation technique is presented. In addition, the multiple-point current sampling (MPCS) technology and linear least square fitting method are used to decrease the current sampling disturbance, which improves obviously the accuracy of position estimation. Finally, the experimental results confirm that the proposed strategy can obtain the rotor position accurately and simply.

Independent Phase Current Reconstruction Strategy for IPMSM Sensorless Control Without Using Null Switching States

This paper proposes a new phase current reconstruction scheme without using null switching states for interior permanent magnet synchronous motor (IPMSM) sensorless control. The phase currents are independently reconstructed and no additional test voltage pulses are required. First, the principle of the basic phase current reconstruction for IPMSM drive system is analyzed in detail. Then, an independent phase current reconstruction scheme without using null switching states is proposed. The current reconstruction dead zone is divided into six sectors, and each sector is split into three parts with corresponding vector synthesis methods. Meanwhile, the null switching states, $V_{000}$ and $V_{111}$ , are removed from the proposed scheme. In this case, the zero vector is synthesized by the other available vectors. Finally, the reconstructed three-phase currents are utilized for high frequency sine-wave voltage injection-based position estimation. The effectiveness of the proposed scheme is verified by experimental results on a 5 kW IPMSM motor prototype, which shows that the reconstructed phase currents track the actual currents accurately under different working conditions.

Sensorless Control of IPMSM Drive using EKF with Electromegnetic Noise Effect

This paper proposes a new move toward to assess the performance of sensorless control of interior permanent magnet synchronous motor (IPMSM) drive along with electromagnetic noise effect by using EKF. Normally in rotary condition, rotor position and speed estimation of IPMSM drive are drawn through an Extended Kalman Filter (EKF) algorithm by measuring its voltages and currents of the stator. The main drawback in developing EKF is it may not proficient to consider the effect of electromagnetic noise which is mainly produced during the time of different speed ranges. Owing to this reason this may cause to vary the motor flux linkages which are significant to find the rotor position and speed by EKF method will give approximate results. To carry on this process, we present the simulation results for sensorless speed control of IPMSM drive by using EKF algorithm with the incorporation of a noise signal which is corresponding to the frequency of electromagnetic noise signal using MATLAB/Simulink software. The armature current, rotor position, and speed estimation are analyzed under this noise signal effect and the effectiveness of the EKF for sensorless control of IPMSM drive is observed.

Low-Frequency Pulse Voltage Injection Scheme-Based Sensorless Control of IPMSM Drives for Audible Noise Reduction

High-frequency (HF) signal injection has been widely used in the sensorless control of interior permanent magnet synchronous motor (IPMSM) drives for zero- and low-speed operation. However, the audible noise pollution caused by induced HF current has restricted its application. To solve this problem, a low-frequency (LF) pulse voltage injection scheme is proposed in this paper. Different from the traditional LF injection methods, by separating the injection and the control periods, it is easy to extract the fundamental and the induced currents without digital filters, which makes the position estimation more realizable. Since the accuracy of position estimation decreases, an enhanced vector-tracking observer based on the harmonic analysis of the discrete position signal is proposed. Then, the stability of the proposed observer is analyzed. The negative effects of estimation errors on position estimation are investigated, and notch filters are adopted to achieve further harmonic reduction. Finally, this sensorless control method is verified by experiments on a 2.2-kW IPMSM drive platform.

Online Parameter Identification for Model-Based Sensorless Control of Interior Permanent Magnet Synchronous Machine

This paper proposes an online identification method that can accurately estimate the stator resistance and dq -axis stator inductances for the effective model-based sensorless control of interior permanent magnet synchronous motors (IPMSMs). The proposed affine projection algorithms are uniquely designed in the estimated rotating γ-δ frame to precisely identify the parameters mentioned above. The two time-scale approaches are employed in the affine projection algorithms to estimate the three electrical parameters. Despite the electrical parameter variations due to the temperature change and magnetic saturation during operation, the rich enough data are provided to the affine projection algorithms in the discrete-time domain to accurately retrieve the updated parameters. These correctly estimated parameters are adapted to the extended back electromotive force observer for the sensorless control of IPMSM drives. Hence, the adaptation of online updated parameters makes the observer stable and robust to parameter variations as compared to the conventional observer without updated parameters. The MATLAB/Simulink-based simulation results and experimental results via a prototype IPMSM test-bed having TMS320F28335 DSP are given to verify the accurate convergence of the estimated parameters, which results into a stable sensorless control system under various operating conditions.

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.

Implementation of sensorless IPMSM drive using the stator current space vector orientation reference frame

Purpose In this paper an adaptive nonlinear control scheme has been proposed for direct torque and flux control of interior permanent magnet synchronous motor (IPMSM) without using mechanical sensor. Design/methodology/approach In this control method the stator resistance is online estimated by adaptive input-output state feedback linearization (AIOFL) controller. Based on proposed control scheme, the strategies of the maximum torque per ampere (MTPA) and maximum power factor (MPF) have been tested using a so-called stator flux search method. Findings The motor equations are transferred from the stationary reference frame to the (SX-SY) two-axis frame of the current by the stator current angle. In this frame, the Y component of the motor current is set to zero and the implementation of the nonlinear controller is independent of the two-axis inductances, the rotor magnetic flux, and position. Practical implications The effectiveness and capability of the proposed control method has been verified by simulation and experimental results. The proposed control scheme can be used for the sensorless control of IPMSM drive in industrial applications such as electric vehicle, traction system, and air conditioner. Originality/value The proposed controller is developed in a special axis (X-Y) rotating reference frame with the X-axis in coincide with the machine current space vector so that there is no need to use and know the machine inductances and rotor position.