Improved Rotor Position Estimation Research Articles

An Improved Rotor Position Estimation Method for SPMSM With Misaligned Hall-Effect Sensor

This paper presents an improved rotor position estimation method for surface permanent magnet synchronous motor (SPMSM) using a low-resolution Hall-Effect sensor. Firstly, an observation function is proposed to detect the speed variation, and a novel correction method based on optimization process is proposed to identify and correct the deviation angle caused by sensor misalignment. Then, an improved position observer is introduced using a gain-scheduling controller to achieve better performance in both steady state and transient state. The proposed method enhances the anti-perturbation and start-up capability for SPMSM and compensate the misalignment effect of Hall-Effect sensors. Experimental results are demonstrated to verify the effectiveness of the proposed method.

Improved Rotor Position Estimation Method for Brushless Synchronous Starter/Generator Based on Field Harmonic Signals Self-Injection Scheme

An improved rotor position estimation method for brushless synchronous starter/generator (BSSG) operating at zero and low speed based on the field harmonic self-injection scheme is proposed. The 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nd</sup> harmonic generated by the rotating rectifier in the field winding of the main generator (MG) is employed as a self-injected high-frequency (HF) signal instead of an extra signal injection. An improved rotor position asynchronous demodulation method without a low-pass filter (LPF) is presented to achieve the simple signal processing, where a dual second-order generalized integrator (DSOGI) is designed to extract the response HF signals and their orthogonal signals. The phase shift of rotor position due to the signal extraction procedure is analyzed, and the corresponding compensation strategy is given to achieve high-accuracy estimated rotor position for the sensorless starting control. Finally, the feasibility and effectiveness of the proposed rotor position estimation method are verified through the comparative simulation and experiment results.

Improved Position Sensorless Drive Method for IPMSM Based on Fully Discretized Model and Inductance Identification Utilizing Current Ripple

This article proposes an improved position sensorless drive method for interior permanent magnet synchronous machines (IPMSM) in medium- and high-speed regions, which relies on the fully discretized extended back-electromotive force (EEMF) model and online inductance identification. First, the fully discretized EEMF model is developed for constructing position observers, which overcomes the accuracy deterioration of the conventional Euler-discretized model with the speed increasing. And then, an online inductance identification method for IPMSM, which utilizes the inherent pulsewidth modulation (PWM) current ripple of the voltage source inverter (VSI), is proposed to improve the position estimation accuracy. Compared with the traditional parameter identification method, the proposed method does not require the additional signal injection, therefore, the undesirable torque fluctuation and additional voltage occupancy due to signal injection are avoided. Benefiting from the fully discretized EEMF model and the estimated inductances, the improved rotor position estimation of IPMSM can be achieved. Finally, the proposed method is verified by simulations and experiments.

Stator Flux Producing Current-Based Promoted Rotor Angle Estimator of Doubly-Fed Induction Generator for Encoderless Operations

In the context of position or speed sensorless control scheme, an improved rotor position estimation process for doubly-fed induction generator (DFIG) is presented in this paper. Model reference adaptive system (MRAS) is considered for the computation of rotor position. The stator flux producing current is taken as main working variable for the estimator. The estimator has various desirable features such as free from integrator-differentiator based computation, no information needed about initial rotor position (catch on fly operation), capability to work at very low slip condition (near synchronous speed operation), non-involvement of flux calculation, negligibly sensitive to mismatch in machine parameters. The major advantage of the proposed scheme is that it is insensitive to magnetizing inductance and rotor resistance of the electrical machine. Also, the novelty of the estimator lies in the fact that the suggested estimator works stably and accurately from very light load to full load operating conditions. The robust operation of proposed estimator is verified through real-time experimental set up.

A Vector Controlled Drive System for Electrically Power Assisted Steering Using Hall-Effect Sensors

Permanent Magnet Synchronous Motors (PMSMs) have been replacing conventional DC motors in numerous automotive applications. One of which is Electrically Power Assisted Steering Systems (EPAS). PMSMs offer better performance and a longer lifetime while slightly increasing the system’s cost and complexity. In a vector-controlled PMSM drive system, the rotor position sensor’s resolution plays a vital role in the overall system performance. The better the resolution, the higher the cost. Although numerous sensor-less control algorithms currently exist, machine startup and operation with dynamically changing set-points and loads still impose a challenge for such an approach. For this reason, inexpensive Hall-Effect sensors have been recently used along with a proper position estimation algorithm to provide high-resolution rotor position. In this paper, an implementation of a vector-controlled drive system is applied to an EPAS using only low-resolution Hall-Effect sensors. Additionally, an improved rotor position estimation algorithm based on speed integration is developed to decrease estimation errors and torque ripples in the case of direction reversal. This is to cater to the dynamically changing commands encountered during the normal power assist operation. Comparisons of the proposed rotor position estimation system with the conventional technique are introduced. A complete representation of the proposed system is built using MATLAB/Simulink. An experimental setup is developed and built around a Motor-Driven Power Steering (MDPS) unit which is a column-assist type EPAS system made by Hyundai Mobis. The simulation and experimental results are presented to verify and evaluate the effectiveness of the proposed algorithm.

Improved Rotor Position Estimation Accuracy by Rotating Carrier Signal Injection Utilizing Zero-Sequence Carrier Voltage for Dual Three-Phase PMSM

In this paper, the rotor position estimation accuracy of rotating carrier signal injection utilizing zero-sequence carrier voltage method for dual three-phase (DTP) permanent-magnet synchronous machines (PMSMs) is investigated. When utilizing the zero-sequence carrier voltage, the system bandwidth and rotor position estimation accuracy can be significantly enhanced. However, undesirable sixth harmonic estimation error occurs for single three-phase PMSM with rotating signal injection due to multiple saliency components in the zero-sequence carrier voltage. To solve such a problem, the existing methods require time-consuming offline measurements and complex structures. Fortunately, for the case of DTP-PMSM drives, thanks to the existence of additional degrees of freedom, two high-frequency signals can be injected independently for two winding sets. Therefore, by applying the optimum phase shift angle between the injected signals, a modified rotating carrier signal injection using zero-sequence voltage-based sensorless control strategy is proposed to suppress the sixth harmonic position errors. In addition, a new simple measurement method of zero-sequence carrier voltage is proposed where one voltage sensor is placed between the two isolated neutral points. The proposed method can achieve improved rotor position estimation accuracy with low computational burden. The experimental results verify the effectiveness of the proposed strategy.

Rotor position estimation for single- and dual-three-phase permanent magnet synchronous machines based on third harmonic back-EMF under imbalanced situation

In this paper, an improved rotor position estimation strategy based on third harmonic back-EMF for single- and dual-three-phase permanent magnet synchronous machines (PMSMs) under imbalanced situation is proposed. Due to the imbalanced machine impedance, back-EMF or sensing resistor network, the measured triplen harmonic back-EMF will contain certain fundamental component distortion which may severely deteriorate the performance of rotor position estimation. With the aid of the fundamental component compensator, this distortion can be significantly compensated, and the rotor position estimation error can be minimized considerably. The proposed strategy has been implemented on a dSPACE platform with a prototype of dual-three-phase PMSM with serious imbalanced parameters, and operate at single- and dual-three-phase conditions. The experimental results prove that the proposed strategy can significantly improve the steady-state and dynamic performance of rotor position estimation under imbalanced situation.

Acoustic Noise Reduction of BLDC Motor Drive Using One-Cycle Current Control Strategy

Torque ripple and resulted acoustic noise and vibration are the main disadvantages of brushless DC (BLDC) motor drives. In this study, One-Cycle Control (OCC) is developed for current regulation of brushless DC (BLDC) motor drive as a unified constant-frequency integration control strategy. Employing one-cycle control strategy reduces high frequency torque ripple of conventional hysteresis current controllers leading to lower acoustic noise and vibration in the drive. To enhance reliability and reducing drive cost, an improved rotor position estimation technique is implemented. OCC strategy and sensorless method are realized using a low-cost general-purpose AVR microcontroller (Atmega8). It is shown that torque ripple, acoustic noise and vibration are reduced via OCC method comparing to conventional hysteresis control strategy. Computer simulations and experimental results with a 375W, 16 poles BLDC motor, demonstrate improved behavior of developed sensorless BLDC drive operation.

Improved Rotor-Position Estimation by Signal Injection in Brushless AC Motors, Accounting for Cross-Coupling Magnetic Saturation

This paper presents an improved signal-injection-based sensorless-control method for permanent-magnet brushless AC (BLAC) motors, accounting for the influence of cross-coupling magnetic saturation between the d- and q -axes. The d- and q -axis incremental self-inductances, the incremental mutual inductance between the d-axis and q -axis, and the cross-coupling factor are determined by finite-element analysis. An experimental method is proposed for measuring the cross-coupling factor which can be used directly in the sensorless-control scheme. Both measurements and predictions show that a significant improvement in the accuracy of the rotor-position estimation can be achieved under both dynamic and steady-state operation compared with that which is obtained with the conventional signal-injection method.