Non-salient Permanent Magnet Synchronous Motor Research Articles

Natural Speed Observer for Nonsalient AC Motors

This letter addresses experimental validation of the reduced-order natural speed observer design for position sensorless drive with nonsalient permanent magnet synchronous motor. The natural speed observer and the active flux estimator are connected in a cascaded fashion, which results in a simple sensorless algorithm that needs only to tune one bandwidth parameter for flux estimation and one bandwidth parameter for speed observation. Experimental results of high speed reversal test, zero speed stopping test, and slow speed reversal test are included, where the practice of applying nonzero <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$d$</tex-math></inline-formula> -axis current at zero speed has shown to be effective for loaded zero speed stopping test, but it causes zero-speed locked-up at slow speed reversal with acceleration rate of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\rm \text{50}\,r/\text{min}/s$</tex-math></inline-formula> . Four remedies are compared to improve the slow speed reversal test and the proposed method gives almost ramp actual speed waveform, nondiverging <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$q$</tex-math></inline-formula> -axis current and smooth transition in position waveform during slow zero speed crossing. A new dynamic expression of the active flux is proposed and with the aid of the active flux concept, the proposed sensorless algorithm is also applicable to various types of ac motors.

Cascaded boost buck converter for solar power driven stand-alone PMSM drive

This paper deals with the boost-buck converter employed solar power based PMSM (Permanent Magnet Synchronous Motor) drive for variable speed compressor of a refrigeration system. A cascaded boost-buck converter is used as a non-inverting DC-DC converter in between solar PV panel and the PMSM drive. An independent control scheme for cascaded boost-buck converter is used to achieve non-inverting output DC bus voltage with maximum power tracking. It allows variable voltage control at PV panel with reduced voltage stress across the boost-buck converter switches under a desired voltage gain and system efficiency. The ZDC (Zero Direct Current) based vector-oriented control is employed for the VSI (Voltage Source Inverter) for speed control of non-salient pole PMSM drive. A DSC (Digital Signal Controller) dSPACE 1104 is used for real time validation. Simulation results are obtained to validate the performance of proposed control algorithms and test results are obtained with a rooftop solar PV panel.

Estimation of Position and Resistance of a Sensorless PMSM: A Nonlinear Luenberger Approach for a Nonobservable System

We show that the pair (rotor position, resistance) of a nonsalient permanent magnet synchronous motor (PMSM) is not observable in the sensorless setting, namely, when only the electrical signals (voltages and intensities) are measured. However, if the rotation speed ω and the current in rotating frame i <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> are not constantly zero, we prove that there only exist a maximum of six indistinguishable solutions, the resistance being the root of a polynomial of degree six. Besides, in the particular case where ω, i <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> , and i <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</sub> are constant, we show that the number of possible solutions is reduced to two, with two well-identified possible values for the resistance. Those two solutions can be dissociated if the sign of i <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</sub> (namely, the mode of use of the motor) is known. Inspired by the nonlinear Luenberger methodology, this property enables us to propose an estimation algorithm, which relies on a one-dimensional minimization of a criterion involving the voltages and intensities filtered at three distinct sufficiently large frequencies. Its performances are tested and illustrated in simulations on real data.

Adaptive Full State Observer for Nonsalient PMSM with Noised Measurements of the Current and Voltage

Abstract An algorithm of adaptive estimation of the magnetic flux for the non-salient permanent magnet synchronous motor (PMSM) for the case when measurable electrical signals are corrupted by a constant offset is presented. A new nonlinear parameterization of the electric drive model based on dynamical regressor extension and mixing (DREM) procedure is proposed. Due to this parameterization the problem of flux estimation is translated to the auxiliary task of identification of unknown constant parameters related to measurement errors. It is proved that when both current and voltage measurements are biased the proposed algorithm ensures convergence of the flux observation error to a bounded set. At the same time the position error converges to zero. The observer provides global exponential convergence if the corresponding regression function satisfies the persistent excitation condition. If the regression function is not square integrable the global asymptotic convergence is ensured. In comparison with known analogues this paper gives a constructive way of the flux reconstruction for a nonsalient PMSM with guaranteed performance (low oscillation, convergence rate regulation) and, from other hand, a straightforwardly easy implementation of the proposed observer to embedded systems.

Sensorless Control of Permanent Magnet Synchronous Motors based on Finite-Time Robust Flux Observer

Abstract A sensorless control algorithm is developed based on novel finite-time robust flux observer for the non-salient permanent magnet synchronous motor (PMSM). Total flux equality and motor model are used to find the linear regression-like model with respect to the flux. Applying dynamic regressor extension and mixing method, we obtain two independent scalar equations and construct a finite-time flux observer. The flux estimate is used to reconstruct the rotor position and velocity with well-known trigonometric relation and phase-locked loop observer, respectively. To complete a sensorless control design, we pass these estimates to standard field orient control. The efficiency and robustness of the proposed approach are demonstrated through the set of numerical simulations.

Stator flux and load torque observers for PMSM

In this paper, a stator flux observer and constant load torque estimation methodare developed for non-salient permanent magnet synchronous motors. The methods described here are based on implementation of LTI filters and linear regression. The motor resistance and inductance are assumed to be known.

Adaptive Flux Observer for Nonsalient PMSM with Noised Measurements of the Current and Voltage

An algorithm of adaptive estimation of the magnetic flux for the non-salient permanent magnet synchronous motor (PMSM) for the case when measurable electrical signals are corrupted by a constant offset is presented. A new nonlinear parameterization of the electric drive model based on dynamical regressor extension and mixing (DREM) procedure is proposed. Due to this parameterization the problem of flux estimation is translated to the auxiliary task of identification of unknown constant parameters related to measurement errors. It is proved that the flux observer provides global exponential convergence of estimation errors to zero if the corresponding regression function satisfies the persistent excitation condition. Also, the observer provides global asymptotic convergence if the regression function is square integrable. In comparison with known analogues this paper gives a constructive way of the flux reconstruction for a nonsalient PMSM with guaranteed performance (monotonicity, convergence rate regulation) and, from other hand, a straightforwardly easy implementation of the proposed observer to embedded systems.

Sensorless interior permanent magnet synchronous motor control with rotational inertia adjustment

Mechanical model is generally required in high dynamic sensorless motor control schemes for zero phase lag estimation of rotor position and speed. However, the rotational inertia uncertainty will cause dynamic estimation errors, eventually resulting in performance deterioration of the sensorless control system. Therefore, this article proposes a high dynamic performance sensorless control strategy with online adjustment of the rotational inertia. Based on a synthetic back electromotive force model, the voltage equation of interior permanent magnet synchronous motor is transformed to that of an equivalent non-salient permanent magnet synchronous motor. Then, an extended nonlinear observer is designed for interior permanent magnet synchronous motor in the stator-fixed coordinate frame, with rotor position, speed and load torque simultaneously estimated. The effect of inaccurate rotational inertia on the estimation of rotor position and speed is investigated, and a novel rotational inertia adjustment approach that employs the gradient descent algorithm is proposed to suppress the dynamic estimation errors. The effectiveness of the proposed control strategy is demonstrated by experimental tests.

Sensorless initial rotor position identification for non‐salient permanent magnet synchronous motors based on dynamic reluctance difference

Due to the equivalence between the d-axis and q-axis static reluctance in non-salient permanent magnet synchronous motors (PMSMs), the traditional saliency-tracking self-sensing strategies appear powerless for rotor position identification. However, the nonlinear magnet saturation characteristic results in much larger d-axis dynamic reluctance than that in q-axis, then two novel methods based on the dynamic reluctance difference are proposed for sensorless initial rotor position detection. In the high frequency rotating voltage injection method, the positive-sequence and negative-sequence second-harmonic carrier current components are used to estimate two pre-angles simultaneity and separately, where the final estimated rotor position is calculated with the offset angle caused by q-axis dynamic reluctance eliminated. In the high frequency pulsating voltage injection method, the cosine second-harmonic carrier current component contains rotor position and magnet polarity information. The position signal is employed to estimate the possible pre-angles from three symmetrical and equidistant initial estimated angles respectively, where the pre-angle with the largest and negative polarity signal is the final estimated rotor position. Both methods can accomplish the rotor position estimation without an additional polarity detecting process. The simulation and confirmatory experimental results on a surface-mounted PMSM demonstrated the proposed methods can estimate initial position reliably and fast at standstill.

Parameter Identification of PMSM Using Immune Clonal Selection Differential Evolution Algorithm

Permanent magnet synchronous motor (PMSM) models with accurate parameters are crucial to high performance PMSM control system designs. As the estimation of PMSM parameters is very difficult due to thenonlinearmodel complexity, a novel immune clonal differential evolution algorithm (ICDEA) is proposed to identify the electrical parameters of nonsalient pole PMSM. Clonal selection and receptor editing mechanism are introduced to ICDEA to increase the diversity of the population and improve searching capability. The effectiveness of the proposed identification method is verified by both simulation and experiment. The results show that the proposed algorithm has good convergence in simultaneously estimating stator resistance,dq-axis inductances, and rotor flux linkage. In addition, the convergence speed of ICDEA is compared with other differential evolution (DE) algorithms, which verifies that the ICDEA has better performances in global searching.

Sensorless Position Control for Surface Permanent Magnet Synchronous Motors at Zero Speed and Acceleration

This paper proposes a position, speed and load torque observation technique for position control of a non-salient Permanent Magnet Synchronous Motor (PMSM). Unlike the speed control, the position control implies that the motor is often in low speed and standstill conditions. Observability analyze is done to show that the motor is not observable in standstill condition. A high-frequency signal injection is introduced to get round this unobservability. An Extended Kalman Filter is then used to observe the rotor position, speed and load torque by taking into account the injected signal into the observation model. Position tracking and load torque influence are studied on a test bench. Experimental results are provided to confirm the performance and efficiency of the proposed solution.

A sliding mode speed and rotor position estimator for PMSM

The paper discusses the problem of state estimation for the non-salient permanent magnet synchronous motor (PMSM) and presents a method for estimation of speed and rotor position based on a sliding mode (SM) EMF observer. The observer is developed based on the full order PMSM model in the stationary reference frame. The motor speed is a required input in the proposed observer and a speed estimate obtained from the output rotor position is used. The SM observer is analysed using Lyapunov’s theory of non-linear stability and is validated by simulations and experimental tests. The proposed method is applicable in a sensorless PMSM drive; the estimator uses only the measured motor voltages and currents and produces estimates of the speed and rotor position. The influence of the feedback gains of the SM observer is discussed. The method is relatively simple to implement, involves a reduced number of design gains, does not require correction of the rotor position and has excellent accuracy for a wide speed range and at low speed.

Speed and rotor position estimation of PMSM by sequential sliding mode observers

The paper presents a speed and EMF estimator for the non-salient permanent magnet synchronous motor (PMSM). The method uses only the measured motor voltages and currents of the motor; estimation is done with two sliding mode (SM) observers that run sequentially. A first SM observer estimates the EMFs of the motor in the stationary reference frame. These are passed as inputs to a second SM observer that estimates the speed and reestimates the EMFs. The method is applicable in a sensorless speed controlled PMSM drive where the EMFs are used to provide field orientation and the estimated speed is used for speed feedback. The paper proves the convergence of the observers and discusses the design of the gains. The theoretical development is supported with simulation results and experimental tests. The advantages of the proposed method compared to the state of the art are discussed.

PMSMセンサレス駆動のための力率位相形ベクトル制御法

This paper proposes a new simple vector control method for sensorless drive of permanent-magnet synchronous motors (PMSMs). The proposed method takes an approach to estimate directly phase of the quasi-optimal stator current through control of the power factor phase instead of estimation of rotor phase. It is established based on new analysis of motor characteristics and has the following attractive features: 1) it can be applied to both of salient and non-salient pole PMSMs; 2) stator current control quasi-minimizing copper and/or iron loss is directly performed; 3) it is insensitive to motor parameter variation, and does not requires motor parameters with precision; 4) it is simple. Simple and practical rules for selecting design parameters of the method are clearly given based on the analysis. Effectiveness of the analysis and usefulness of the proposed method are verified through experiments.

Synchronization at startup and stable rotation reversal of sensorless nonsalient PMSM drives

In this paper, a variant of the well-known "voltage model" is applied to rotor position estimation for sensorless control of nonsalient permanent-magnet synchronous motors (PMSMs). Particular focus is on a low-speed operation. It is shown that a guaranteed synchronization from any initial rotor position and stable reversal of rotation can be accomplished, in both cases under load. Stable rotation reversal is accomplished by making the estimator insensitive to the stator resistance. It is also shown that the closed-loop speed dynamics are similar to those of a sensored drive for speeds above approximately 0.1 per unit, provided that the model stator inductance is underestimated. Experimental results support the theory.

A New Sensorless Vector Control Method for PMSM Based on a New 4th-Order State-Observer in Stationary Reference Frame with the "Integral-Feedback Type Speed Estimator"

This paper proposes a new sensorless vector control method for permanent-magnet synchronous motors (PMSM), which uses a new full-order (4th order) state-observer in stationary reference frame combined with the “integral-feedback type speed estimation method". The proposed method can be applied to both of salient and nonsalient PMSM.

Unified sensorless vector control of synchronous and induction motors

In this paper, a unified theory for sensorless flux estimation and vector control of induction motors and nonsalient permanent-magnet synchronous motors (PMSMs) is developed. It is shown that an estimator and vector controller for one of the motor types can also be applied to the other, with only minor modifications necessary. Two candidate estimators are considered: a variant of the well-known voltage model (VM) and a phase-locked-loop-type speed and position estimator. These are applied to both motor types, and evaluated experimentally. For the nonsalient PMSM, an important result is that synchronization can be guaranteed from any initial rotor position.

Adaptive Observer for Sensorless Control of Permanent Magnet Synchronous Motor Drives

This paper develops a sensorless control method for nonsalient permanent magnet synchronous motor drives. The position and speed estimations are based on the back electromotive force (emf) estimation in f g stator reference. Two equivalent solutions are developed to estimate the back emf (i.e., the adaptive filter technique), and alternatively, an extended disturbance observer, both being speed adaptive. The position estimation is computed directly from the back emf components. The speed estimation uses a model reference adaptive observer as a sinusoidal oscillator external synchronized by the back emf with (i) an amplitude adaptive correction speed depending, and (ii) a phase correction realized by an adaptive mechanism using a variable structure plus a proportional integral compensator. The speed sign is included. The speed and position observers can be independently tuned, and the estimations are robust to parameter deviations. A relatively large speed range of 1:100 is obtained. Extensive simulation results are given and discussed.