Position Sensorless Control Method Research Articles

A position sensorless hybrid control method for electrically excited synchronous motor

A position sensorless hybrid control method for electrically excited synchronous motor

Sensorless HSPMSM Control of an Improved SMC and EKF Based on Immune PSO

Here, for controlling a high-speed flywheel permanent magnet synchronous motor (HSPMSM), a position sensorless control method for estimation of motor rotor position and speed is proposed to address the problems faced by mechanical position sensors of high cost, large size, and poor interference immunity. The extended Kalman filter (EKF) has difficulty obtaining the optimal covariance matrix when performing state estimation. Therefore, the particle swarm algorithm (PSO) with an immune mechanism is used to optimize the covariance matrix of the EKF. However, the EKF algorithm makes the system less robust due to its delay effect. Based on the traditional sliding mode control rate, the exponential convergence law is improved, and the continuous function sat(s) is used instead of the symbolic function sgn(s). This improves the convergence law and proves the asymptotic stability of the designed sliding mode variable structure controller based on Lyapunov’s stability theorem. Then, the novel control law is applied to the sliding mode surface (SMS). An ordinary sliding mode controller (OSMC) using a linear sliding mode controller (LSMC), a global sliding mode controller (GSMC) using a global sliding mode surface (GSMS), and an integral sliding mode controller (ISMC) using an integral sliding mode surface (ISMS) are designed for improving control. Joint simulation in MATLAB and Simulink verifies that the optimized EKF based on the immune PSO can improve precision and accuracy for controlling the electronic rotor position and speed. Comparing the new sliding mode controller with a traditional PI controller reveals that the proposed system has stronger resistance to load disturbance and better robustness.

Position Sensorless Control of Dual Three-Phase IPMSM Drives With High-Frequency Square-Wave Voltage Injection

Dual three-phase interior permanent-magnet synchronous motor (IPMSM) drives have received more attention by the merits of better fault-tolerant capability and lower torque ripples. To improve the reliability of the system against failures in position sensor, it is necessary to investigate the position estimation method for dual three-phase IPMSM drives. The high-frequency (HF) signals injection is utilized for position estimation in three-phase IPMSM drives during low-speed operation region. However, the torque ripples are inevitable owing to the mixing of fundamental and HF components in the same control space for three-phase IPMSM drives. In this paper, the position sensorless control method has been proposed by injecting HF square-wave voltage in the harmonic subspace for the dual three-phase IPMSM drives. Since the harmonic subspace is decoupled from the torque subspace, the torque disturbance can be mitigated well with the proposed HF signal injection based position sensorless method. Moreover, the digital filters in signal extraction and current feedback can be avoided and the signal separation process becomes easy with the proposed method. The experiments have been conducted to validate the performance of the proposed method.

High‐frequency square‐wave voltage injection position sensorless control method using single current sensor

AbstractHigh‐frequency (HF) square‐wave voltage injection position sensorless control method for interior permanent magnet synchronous motor (IPMSM) is widely utilised in zero and low speed range due to its good dynamic performance and easy implementation. However, this method relies on the sampling accuracy of current sensors for rotor position estimation. To overcome this restriction, an HF square‐wave voltage injection position sensorless control method for IPMSM using a single current sensor (SCS) is proposed. Firstly, the impact of current sampling errors on HF square‐wave voltage injection position sensorless control is analysed, and it is concluded that the scaling errors of current sensors will cause the estimated position to oscillate at twice the fundamental frequency. Based on this conclusion, the phase currents reconstruction technology with SCS is adopted to avoid the impact of scaling errors on rotor position estimation. To reconstruct the phase currents containing HF component, a PWM cycle is divided into two parts, sampling stage and injection stage. By this way, the impact of HF square‐wave voltage injection on current reconstruction can be avoided. Then, the rotor position estimation is realised. The experiments are performed on a 20‐kW IPMSM platform and the results verify the effectiveness of the proposed method.

High-Frequency Signal Injection-Based Sensorless Control for Dual-Armature Flux-Switching Permanent Magnet Machine

The new topology of the dual-armature flux-switching permanent magnet machine (DA-FSPM) leads to new characteristics and issues in the control of the machine, of which the mutual inductance of the two sets of armature windings is the most important one. This paper proposes a novel position–sensorless control method based on high-frequency injection (HFI) for DA-FSPM. The high-frequency model of the machine is derived, and the theory of the position estimation method is proposed. Different from the conventional HFI-based position estimation method, the proposed method utilizes the mutual inductance of the DA-FSPM rather than the machine saliency. Meanwhile, because the extracted position information based on the mutual inductance is more obvious, the proposed method also has better steady and dynamic performance. Then, the position observer based on the phase lock loop and the initial position detection method for the DA-FSPM is proposed. The experiments are executed on a DA-FSPM prototype with three-phase stator windings and five-phase rotor windings to prove the effectiveness and superiority of the proposed method.

Improved Position Sensorless Control for PMLSM via an Active Disturbance Rejection Controller and an Adaptive Full-Order Observer

Position and speed information are very important to realize the efficient control for permanent magnet linear synchronous motor (PMLSM). In order to obtain more accurate position estimation signals, this article investigates an improved position sensorless control method for PMLSM by combining an active disturbance rejection control (ADRC)-based speed controller and an adaptive full-order observer (AFO)-based position estimator. The AFO is constructed based on model reference adaptive system (MRAS), which can obtain more accurate position estimation signal by introducing a current error feedback gain matrix. However, there are lots of thrust fluctuations existing in PMLSM caused by end effect, which will affect the estimation accuracy. Since it is difficult to reduce the influence of thrust fluctuation by only improving the observer itself, an ADRC-based speed controller is designed to improve the anti-interference ability of control system, thereby improving the position estimation accuracy. For the ADRC controller, an second-order linear extended state observer (LESO) is designed to observe the thrust fluctuation and an nonlinear state error feedback (NLSEF) control law is introduced to compensate the observed disturbance. The effectiveness and superiority of the proposed method have been verified by simulation and experimental results.

Position Sensorless Control for PMSM Drives With Single Current Sensor

The aim of this article is an attempt to provide a more credible control mode or a fault-tolerant control strategy for permanent magnet synchronous motor (PMSM) drives when an unexpected failure occurs to the current or position sensor. Considering that, a position sensorless control method that uses only one current sensor is proposed. Different from a traditional position sensorless control scheme that utilizes additional current sensors to obtain information of multiple phase currents, only a single current sensor (SCS) arranged on one of the current branches is included among the whole control circuit. Three-phase currents are reconstructed by sequentially sampling the SCS under specific voltage vectors, and directly employed for motor position estimation. A nonlinear position observer established according to the gradient descent is adopted. Focusing on the special current-acquisition pattern in this article, a step-size optimization method based on golden section search is proposed to minimize position estimation error. The experimental results reveal that the method in this article is comparable to the traditional full-current-sensor method in terms of position estimation, which confirms the fault-tolerant capability as one certain sensor of the control structure malfunctions.

A Controlled Mechanical–Electronic Hybrid Commutation Theory and Position Sensorless Control

Both brushed dc motors and brushless dc motors have a wide range of applications, but mechanical commutating devices have the problem of harmful commutation arcs, and electronic commutating devices increase the cost of control systems. The uncontrolled mechanical–electronic hybrid commutating device passively controls the voltage of the freewheeling commutator segment through the capacitor, but the capacitor, inductor and resistor with fixed parameters in the freewheeling circuit are difficult to apply to the entire operating range. Therefore, this article proposes a controlled mechanical–electronic hybrid commutating device and a position sensorless control method. The mechanical component realizes the conduction mode of 120 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> square waves through brushes and a mechanical commutator. The electronic component actively controls the voltages of the commutator segments through the power electronic switches in the commutation circuit so that the brush and the newly separated commutator segment remain equipotent, and the gap between them does not bear voltage, which is equivalent to operating in the brush-slip ring state and completely solves the problem of sparking and arcing during the commutation process. The controlled hybrid commutating device requires only two switches to obtain the same commutation effect as the electronic commutating device with six switches and does not require a position sensor or control chip, which reduces the system cost. The validity and feasibility of the controlled mechanical–electronic hybrid commutation theory and device are verified by experiments.

An Online Compensation Method of VSI Nonlinearity for Dual Three-Phase PMSM Drives Using Current Injection

Compensation of voltage-source-inverter (VSI) nonlinearity is of great importance in parameter identification and position sensorless control method for motor drives. In this letter, a simple online compensation method has been proposed for the dual three-phase permanent-magnet synchronous motor (PMSM) drives. The key is to observe the change of voltage references contained VSI nonlinearity after injecting currents in z1z2-axis purposely. Compared with the existing estimation methods for VSI nonlinearity, the proposed method not only can avoid the tedious and time-consuming offline test for modeling inverter but also can achieve real-time estimation without machine parameters. Moreover, the current injection on z1z2 subspace has a slight influence on the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> subspace (the torque subspace) thanks to the multiple decoupling subspaces of dual three-phase PMSM. The experiments have been given to verify the validity of the proposed method.

A Current Self-Injection Based Position Sensorless Control for DSEG With Controlled Rectification

The controlled rectification method with positon sensor can effectively improve the output power of the doubly salient electromagnetic generator (DSEG), but weakens the advantage of no position sensor for the traditional DSEG with uncontrolled rectification. To solve this problem, a current self-injection based position sensorless control method is proposed for DSEG with H-bridge semi-controlled rectifier (HBSCR) in this article. Based on the operation principle of DSEG and HBSCR, the position estimation method is developed from the positive zero-crossing point of inductive electromotive force (EMF), which is indirectly observed through the test current self-injected by the inductive EMF. According to the relationship between generation current and test current, a test current self-injection method without presetting injection width is put forward, and the corresponding sensorless control strategy is established with the combination of angular position semi-control. Then, the compensation strategy is further presented to improve the accuracy of the proposed position estimation method. Finally, the simulations and experiments are implemented on a three-phase DSEG to validate the feasibility and correctness of the proposed sensorless control strategy.

A phase‐shift‐free synchronous reference frame filter‐based position sensorless control method for open‐winding permanent magnet generator system

An open-winding permanent magnet generator (OWPMG) system that offers features like fewer switching devices and high integration can be used in multi-input generator systems. To achieve high-accuracy position sensorless operation for the OWPMG system, this study investigates a phase-shift-free synchronous reference frame filter (SRFF-PSF) for use in the sliding mode observer (SMO) position sensorless algorithm. The proposed SRFF-PSF can completely restore the fundamental component of back-electromotive force (EMF) without phase shift and filter out the high-order harmonics owing to the following two improvements. First, the fundamental phase lag is eliminated by removing the low-pass filter between the back-EMF and the SRFF. Second, the error iteration of the output position angle is avoided by using the synchronous angle information from an additional phase locked loop module for the coordinate transformation of the SRFF. Based on the aforementioned improvements, the proposed method can effectively solve the phase shift problem in position estimation. The correctness and effectiveness of the method are verified by the experimental results.

Sensorless Speed Control of IPMSM Using Sliding Mode Observer Based on Active Flux Concept

This paper proposes a new speed and position sensorless control method of Interior permanent magnet synchronous motors (IPMSM) using sliding mode observer based on Active Flux concept. First, a new description of IPMSM dynamic model in the stationary reference frame using active flux concept is proposed. The model obtained suits for both SPMSM and IPMSM in the stationary reference frame, Therefore, all that sensorless controls proposed for SPMSM can be directly and easily applied to IPMSM. Secondly, from the measurement of the voltages and the currents, a new analysis of the observability property is developed. Then, the sliding mode observer (SMO) structure and its design method are described in the stationary reference frame by using the active flux equation. A “chattering” phenomenon is reduced by using this technique. The stability of the proposed SMO was verified using the Lyapunov function. The speed and position of the IPMSM are estimated based on back EMF which are related to the active flux. Moreover, the zero d-axis current control strategy is used to control the IPMSM. Finally, the proposed method on the proposed model has been simulated and tested to show the effectiveness of the proposed scheme.

Initial Rotor Position Detection for Permanent Magnet Synchronous Motor Based on High-Frequency Voltage Injection without Filter

The accurate initial rotor position of a permanent magnet synchronous motor (PMSM) is necessary for starting the motor, and for the position sensorless control method adopted by a PMSM control system under some working conditions. This paper presents a new method to detect the initial rotor position of a permanent magnet synchronous motor (PMSM). The method does not need a low-pass filter, and has strong robustness and a simple calculation method. According to the relationship between high-frequency current response and rotor position angle θ, the rotor position angle can be obtained by arctangent and linear formulae. Finally, the magnetic polarity of the rotor is distinguished according to the change of inductance. In this method, the arctangent function is used to eliminate the filtering process and reduce the influence of the parameter deviation of the motor system on the detection accuracy of the initial position. The experimental results verify the correctness of the theoretical analysis and the effectiveness of the method.

Position Sensorless Control Method for Permanent Magnet Synchronous Motors Using Speed Observer and Opened Phase Voltage Caused by Magnetic Saliency

Position Sensorless Control Method for Permanent Magnet Synchronous Motors Using Speed Observer and Opened Phase Voltage Caused by Magnetic Saliency

High-Stability Position-Sensorless Control Method for Brushless DC Motors at Low Speed

In order to improve the stability of brushless DC (BLDC) motors at low speed, a high-stability position-sensorless control method is proposed in this paper. Because the back electromotive force (EMF) is very small at low speed, a novel algorithm is proposed to detect the zero crossing point of back EMF accurately. First, the line-to-line back EMF is computed based on the mathematical model of BLDC motors. Then, a low-pass filter (LPF) with alterable cutoff frequency is used to reduce the disturbance of the line-to-line back EMF. Last, the commutation signal is obtained by detecting the zero crossing point (ZCP) of the line-to-line back EMF. However, the commutation signal is delayed by the LPF. For this reason, based on the three-phase back EMF, a novel compensation algorithm including an open loop and a close loop is proposed to compensate for commutation error. Moreover, the speed feedback has a big delay at low speed. According to this, a novel speed calculation algorithm is presented to decrease the delay. Both the simulation and experimental results validate the high stability and reliability of the proposed method.

Unbalanced ZCP Compensation Method for Position Sensorless BLDC Motor

This letter presents a position sensorless control method of brushless dc (BLDC) motors considering unbalanced zero-crossing detection of back electromotive force (back EMF). The zero-crossing point (ZCP) of back EMF voltage is detected by comparing the dc-link voltage with the back EMF voltage. The unbalanced ZCP detection is caused by the dc-link voltage drop, dc-link offset voltage, and a motor having asymmetric back EMFs. Because the sensorless BLDC motor control is based on unbalanced ZCP detection, issues with torque ripple and current ripple may be increased. Therefore, sensorless operation with unbalanced ZCP detection may be unstable. In this study, an improved sensorless control method based on a simple compensation algorithm using ZCP signals is proposed. Using the proposed control method, balanced commutation instants can be obtained and the benefits of high-performance operation of BLDC motors can be accomplished. Through application of the proposed method, the effectiveness of the proposed method was experimentally verified.

Low-Cost Position Sensorless Speed Control of PMSM Drive Using Four-Switch Inverter

A low-cost position sensorless speed control method for permanent magnet synchronous motors (PMSMs) is proposed using a space vector PWM based four-switch three-phase (FSTP) inverter. The stator feedforward d q -axes voltages are obtained for the position sensorless PMSM drive. The q-axis current controller output with a first order low-pass filter formulates the rotor speed estimation algorithm in a closed-loop fashion similar to PLL (Phase Lock Loop) and the output of the d-axis current controller acts as the derivative representation in the stator feedforward voltage equation. The proposed method is quite insensitive to multiple simultaneous parameter variations such as rotor flux linkage and stator resistance due to the dynamic effects of the PI current regulator outputs that are used in the stator feedforward voltages with a proper value of K gain in the q-axis stator voltage equation. The feasibility and effectiveness of the proposed position sensorless speed control scheme for the PMSM drive using an FSTP inverter are verified by simulation and experimental studies.

An Improved Position-Sensorless Control Method at Low Speed for PMSM Based on High-Frequency Signal Injection into a Rotating Reference Frame

In this paper, a novel sensorless control strategy with the injection of a high-frequency pulsating sinusoidal voltage into a rotating reference frame for a surface-mounted permanent magnet synchronous motor (SPMSM) is proposed. Conventional schemes may face the problems of applying to the motor with no obvious salient pole effect, and the effect of filter on the bandwidth of the system. Different from the conventional schemes, the new proposed strategy injects a high-frequency pulsating sinusoidal voltage signal is injected into the estimate d-q rotating reference frame, and the rotor position information is obtained from the response of injected high-frequency current signal in the $\alpha $ - $\beta $ stationary reference frame other than the d-q rotating reference frame,which can avoid failure of applying to the SPMSM with no obvious salient pole effect. With this approach, band-pass filter, which is necessary in the conventional sensorless control, is removed to simplify the control structure and improve the system dynamic control performance. Therefore, this paper proposes a simple structure, which modulates the high-frequency current signal directly and only passes through the low-pass filter to obtain the estimated rotor position angle. Finally, the feasibility of the improved high-frequency pulsating sinusoidal voltage injection control method is verified by simulation and experiment.

Scheme based on buck‐converter with three‐phase H‐bridge combinations for high‐speed BLDC motors in aerospace applications

High reliability and safety are critical in aerospace applications. This study introduces a novel high-reliable inverter scheme based on buck-converter with three-phase H-bridge combinations and a high-accurate commutation instant shift correction method for high-speed brushless direct current (BLDC) motors. First, the traditional three-phase inverter and buck-converter-based BLDC motor drive system are analysed. Second, the zero-crossing points of back-electromotive force detection circuit are designed and the position detection error is analysed. Third, a speed measurement with enhanced detection frequency and accuracy is proposed. Then, a fast two-stage commutation instant shift compensation method is designed based on the unique speed measurement method. High-reliable and accurate commutations are achieved especially in the high-speed steady state, which improves the speed control precision and decreases the motor driving loss. Finally, the control system design process is proposed and a fault-tolerant-control strategy is presented to enhance the reliability of the system. Experimental results illustrate the effectiveness and practicability of the proposed inverter scheme and the position sensorless control method.

Position sensorless control for doubly salient electro‐magnetic motor based on line‐to‐line voltage

This study first proposes a novel position sensorless control method for doubly salient electro-magnetic motor (DSEM) based on line-to-line voltage. The commutation instants are estimated by comparing the proper line-to-line voltage with a commutation threshold value, which is preset according to motor speed and field current. Since only line-voltage is required, the negative influence of DSEM neutral point voltage variation is eliminated. Moreover in addition, line-to-line voltage has a gain of phase back-electromotive force (EMF), so the application speed range is desired to be extended. Then, the sensorless commutation lags introduced by reluctance back EMFs and low-pass filters are analysed in detail, with the obtained mathematic expressions, a uniform compensation strategy by adjusting the commutation threshold value is proposed. With no need for extra hardware, the compensation strategy has the merit of easy implementation. What is more, to overcome the restriction of the distorted commutation signal arising in freewheeling process, a constraint of three-phase currents is developed to avoid false commutation. Finally, the experiments on a 12/8-pole DSEM validate the correctness and feasibility of the proposed techniques.