Sensorless Control Method Research Articles

Wide-Range Sensorless Control for SPMSM Using an Improved Full-Order Flux Observer

A sensorless control method was recently investigated in the robot and automation industry. This method can solve problems related to the rise of manufacturing costs and system volume. In a vector control method, the rotor position estimated in the sensorless control method is generally used. This study is based on a conventional full-order flux observer. The proposed full-order flux observer estimates both currents and fluxes. Estimated d- and q-axis currents and fluxes are used to estimate the rotor position. In selecting the gains, the proposed full-order flux observer substitutes gain k for the speed information in the denominator of the gain for fast convergence. Therefore, accurate speed control in a low-speed region can be obtained because gains do not influence the estimation of the rotor position. The stability of the proposed full-order flux observer is confirmed through a root-locus method, and the validity of the proposed observer is experimentally verified using a surface permanent-magnet synchronous motor.

Position Sensorless Control of a Reluctance Synchronous Wind Generator Drive with an LC Inverter Filter

—A control structure for an inverter-fed high speed reluctance synchronous generator wind energy conversion system is proposed and investigated in this article. The novel combination of an LC inverter output filter and a hybrid position sensorless control method is used to ensure robustness and reliability of the system. The proposed LC inverter filter and position sensorless control method also allows the inverter unit to be stationed in the tower base instead of in the nacelle. With the LC filter, sinusoidal machine terminal voltages and reduced electromagnetic interference (EMI) from the tower supple cables are ensured. A new estimation method is developed to minimize current and voltages sensors in the drive system with the LC filter, whereby the machine’s stator quantities are estimated, requiring only parameter knowledge of the LC filter. The proposed hybrid position sensorless control algorithm uses the estimated stator quantities to estimate the rotor position. A high-frequency injection position sensorless control method is used at low speeds. The frequency of the high-frequency injection voltage is chosen close to the resonance frequency of the filter and machine model to amplify the high-frequency current response. Excellent dynamic performance of the proposed control drive system is obtained from a 9.6-kW laboratory reluctance synchronous generator drive system.

Sensorless control of hybrid magnetic bearings

A method of sensorless rotor position control in noncontact bearings by output parameters of the electromechanical energy converter is proposed. The physical essence of the method is as follows. As the displacement of an electromechanical energy converter rotor along the axes x and y varies, the conductivity of the air gap and, accordingly, of the magnetic conductivity of the air gap changes; i.e., in the case of the rotor displacement, additional harmonic components of the magnetic induction occur that create additional harmonic components of the electromotive force. The estimation of these harmonic components makes it possible to determine the displacement of the rotor without the use of rotor position sensors. The mathematical apparatus and the sensorless rotor position control algorithm based on this apparatus have been developed for practical implementation of the proposed method.

Sensorless Control of Low-Cost Single-Phase Hybrid Switched Reluctance Motor Drive

This paper presents a sensorless-controlled, low-cost, low-power, and variable-speed drive system suitable for fan and pump applications. The main advantages of this drive system are the low system cost, simple converter structure, and simple but robust sensorless control technique. The drive motor is a special hybrid switched reluctance motor. The proposed sensorless control method beneficially utilizes the stator side PM field and its performance is motor parameter independent. The unique low-cost drive system solution, simple and robust sensorless control features of this drive system, is demonstrated in detail in this paper. Important design details for practical implementation of the sensorless control algorithm are included. The complete drive system performance is validated using a prototype drive system.

Low computational burden grid voltage estimation for grid connected voltage source converter‐based power applications

This study presents a simple and efficient approach for grid voltage estimation based on the converter equations in the stationary reference frame. The proposed technique is adopted for the sensorless operation of the voltage source converter-based power conditioners. In this study, the effectiveness of the proposed estimation method when it is combined with a proportional-resonant (PR)-based current controller is investigated. When the PR controller is combined with the proposed voltage estimation technique, it offers an additional benefit, such that the grid voltage synchronisation is done without using any phase-locked loop or band-pass filter. The proposed sensorless control method shows an excellent steady-state and transient performance. It is proven through extensive simulations and experiments that the grid voltage estimation with a very low computational burden is achieved even when the grid voltage is distorted.

Current Sensorless MPPT Control Method for Dual-Mode PV Module-Type Interleaved Flyback Inverters

This paper presents a current sensorless maximum power point tracking (MPPT) control method for dual-mode photovoltaic (PV) module-type interleaved flyback inverters (ILFIs). This system, called the MIC (Module Integrated Converter), has been recently studied in small PV power generation systems. Because the MIC is an inverter connected to one or two PV arrays, the power system is not affected by problems with other inverters. However, since the each PV array requires an inverter, there is a disadvantage that the initial installation cost is increased. To overcome this disadvantage, this paper uses a flyback inverter topology. A flyback inverter topology has an advantage in terms of cost because it uses fewer parts than the other transformer inverter topologies. The MPPT control method is essential in PV power generation systems. For the MPPT control method, expensive dc voltage and current sensors are used in the MIC system. In this paper, a MPPT control method without current sensor where the input current is calculated by a simple equation is proposed. This paper also deals with dual-mode control. Simulations and experiments are carried out to verify the performance and effectiveness of the proposed current sensorless MPPT control method on a 110 [W] prototype.

固定子巻線中性点電位を利用した永久磁石同期モータの低速センサレス制御

In this paper, we propose a new sensorless control method using the neutral point voltage of stator windings. Each inductance of the three phase coils of the permanent magnet synchronous motor (PMSM) is slightly changed by the rotor magnet flux. As a result, the neutral point voltage also changes depending on the rotor position. According to this principle, the rotor position can be estimated by detecting the neutral point voltage, even in the zero speed region. We implement this technique and show the experimental results.

Audible Noise Reduction Method in IPMSM Position Sensorless Control Based on High-Frequency Current Injection

Methods for sensorless control involving the injection of a high-frequency signal in the low-speed range of the Interior Permanent Magnet Synchronous Motor (IPMSM) have been proposed. However, audible noise is a concern in these methods. We propose a method to reduce the audible noise due to a high-frequency current by minimizing the injection signal amplitude suitable for IPMSM driving states.

Speed Sensor-Less Vector Control Used in DFIG Wind Power Generation Based on EKF Algorithm

Wind power generation system is a typical nonlinear system. As wind speed is changing constantly, induction motor with conventional speed sensor-less control method has great estimated error. Wind power generation system with the control method cannot be good at tracking maximum power point. The paper put forward a novel control method that estimates the angular velocity and the rotor flux of the wind turbine based on EKF, As a result, induction motor with double-loop sensor-less Vector Control is realized. Simulation results show that the control scheme is effective.

A Simple Strategy for Sensorless Speed Control for an IPMSM During Startup and Over Wide Speed Range

This paper presents a hybrid sensorless control for an interior permanent magnet synchronous motor (IPMSM) for zero-, low-, and high-speed regions. Many sensorless control methods such as an observer-based estimator have been introduced. However, most of the observer- based estimators have a disadvantage at start-up and in the low-speed region. To solve this problem, a simple strategy of using a hybrid system is proposed by integrating a high-frequency (HF) signal injection method and a full-order flux observer. In addition, an HF signal injection method with only a low pass filter (LPF) is proposed to simplify the hybrid system. The hybrid system achieves high- performance drive throughout the entire speed range. The effectiveness of the proposed hybrid technique is verified by experiments using an 11-kW IPMSM drive system.

Position Signal Faults Diagnosis and Control for Switched Reluctance Motor

An accurate rotor position signal is quite necessary for high-performance control of switched reluctance motor (SRM). In general, the position signal faults may lead to abnormal operation, which deteriorates the reliability of the switched reluctance drive system. Thus, it is quite vital but still a challenge to develop a control strategy that can diagnose and control the position signal faults in an autonomous way. In this paper, a square-wave position signal edge prediction-based control strategy is proposed for position signal faults diagnosis and position faults recovery. Integrated with the rotor position fault-tolerant control method, the SRM drive system can maintain reliable operation under different position signal fault conditions. In addition, a phase inductance slope-based sensorless control method is proposed for position fault-tolerant control under the extreme case with failure of all position signals. To verify the validation of the proposed methods, the experiments have been implemented in a 12/8 structure SRM prototype. The results show that the proposed control methods can further improve the fault-tolerant capability of the SRM system.

Improved sensorless direct torque control method using adaptive flux observer

A simple structure and a quick and robust response of the direct torque control (DTC) makes it attractive in ac drives. However, in sensorless applications, a precise estimation of the rotor speed is a crucial issue as along with the torque and flux estimation. In this paper an adaptive flux observer is introduced with a stator current and flux vector components as state variables and rotor speed as an unknown parameter which is estimated by using an adaptive scheme. A non-linear inverter model is proposed to obtain a more accurate response. Also, torque, flux and current pulsations, during the steady-state conditions, are considered as the disadvantages of the classical DTC method. A combined DTC and space vector modulation strategy is presented by using fuzzy logic control (FLC). FLCs are designed to obtain a fast response in the transients, and a high accuracy during the steady-state conditions.

Sensorless Control Method for PMSM Based on Frequency-Adaptive Disturbance Observer

The rotor angle can be estimated from the stator flux in permanent magnet synchronous motor (PMSM). Although integrations are essential to estimate the stator flux from the voltages and currents in the stationary reference frame, disturbances can arise in the process of integrations due to practical reasons. In this paper, a frequency-adaptive disturbance observer has been proposed to remove the disturbances in estimating the stator flux and to enhance the accuracy of the rotor angle estimation. The design and utilization of the proposed observer are detailed under the consideration of its application to a practical system driving PMSM. The performance of the proposed sensorless method has been mainly assessed through experiments at low speed operations, where the sensorless drive of PMSM is regarded as being extremely difficult without the signal injection.

Sensorless Control for PMLSM Based on Fuzzy Sliding Mode Observer

In this paper, a new sensorless control method is proposed for a permanent magnet linear synchronous motor based on Fuzzy sliding mode observer, which combines the advantages of sliding mode observer and Fuzzy controller respectively. The difference between the current estimated value and the actual current value is regarded as sliding mode function; sliding mode function (current error) and variation of the error are used as the input of fuzzy controller, and the width of the boundary layer as the output, adjusting the width of the boundary layer dynamically in real time. The simulation results show that Fuzzy sliding mode observer is able to find a balance between soft chattering and steady-state error, keep the system robustness and control precision.

Sensorless resistive-based control of shape memory alloy actuators in locking mechanism

This article presents a sensorless resistive-based control method to control shape memory alloy wire actuators to be used in the development of a laparoscopic surgical locking system. Shape memory alloy wire electrical resistance is measured to control the martensite phase fraction of shape memory alloy wire. The martensite phase fraction is calculated based on mathematical heating model, resistance models, and the measured resistance. Experiments are conducted to evaluate the validity and performance of the method in the control of the locking system angle. The results show that the sensorless resistive-based control method accurately controls the wire without using any position sensors, resulting in the lower cost, size, and weight of the system. The results show very small steady-state errors, verifying the practicability of this method. The sensorless resistive-based control method has the potential to be used in many applications in which cost and space are limited and the use of an external sensor is impossible or costly.

Speed Control of Doubly Star Induction Motor Using Direct Torque DTC Based to on Model Reference Adaptive Control (MRAC)

This paper presents the analysis and simulation of the control of double star induction motor, using direct torque control (DTC) based on model reference adaptive control algorithm (MRAC). The DTC is an excellent solution for general- purpose induction drives in very wide range the short sampling time required by the TC schemes makes them suited to a very fast torque and flux controlled drives as well the simplicity of the control algorithm. DTC is inherently a motion sensorless control method. The model reference regulator (MRAC) can improve the double star induction motor performance in terms of overshoot, rapidity, cancellation of disturbance, and capacity to maintain a high level of performance. Simulation results indicate that the proposed regulator has better performance responses. The implementation of the DTC applied to a double star induction motor based on model reference regulator is validated with simulated results.

Simulation and Experimental Studies of Speed Sensorless Control of Permanent Magnet Synchronous Motors for Mine Electric Locomotive Drive

This paper presents a novel sensorless control method of permanent magnet synchronous motors at standstill and low speed based on a low-frequency current signal injection. The approach superimposes a persistent LF current signal into the estimated d-axis to get the rotor position error angle-related signal by detecting the corresponding voltage response and current response. Then the rotor position and motor speed are obtained. Theoretical analysis and simulation results demonstrate that the approach can achieve sensorless control of permanent magnet synchronous motors at zero and low speed, ensure good dynamic and static performances, and achieve effective control when applied to servo system. Finally, a test prototype system which used a digital signal processor and space vector pulse width modulation technology has been developed. Experimental results show that the system has better static, the effectiveness and dynamic performance of the adaptive test signals in a sensorless controlled surface-mounted permanent magnet synchronous machines.

A Switching Flux-linkage Reference-based Sensorless Method for Switched Reluctance Motor Drives

A switching flux reference estimation based method for sensorless control of switched reluctance motors is proposed in this article. The basic idea of the method is to estimate switching-on and switching-off flux linkage references from the giving switching angles range and measured phase current. Real-time comparing the estimated flux linkage with estimated switching flux references, the driving signals can be obtained for sensorless control and rotor speed estimation. For closed-loop control, switching-off angle is fixed for speed estimation, and switching-on angle is regulated by the speed deviation proportional-integrator controller. The process to estimate the switching flux references is greatly simplified compared with conventional flux/current methods; it is easily implemented and is suitable for low-cost industry applications. To verify the proposed method, experiments were conducted on a 1-kW, 3-phase 12/8 switched reluctance motor. Experimental results show that speed variable performance of the sensorless drive is comparable with that of position sensors.

Bezczujnikowe sterowanie silnika wysokoobrotowego PM BLDC przy pomocy metody bazującej na napięciach międzyfazowych

The paper presents a sensorless control method based on phase-to-phase voltages of a high-speed PM BLDC motor. In addition, the paper compares this method with other sensorless control methods considering the possibilities of implementation in a high-speed motor. In particular, also highlighted the possibility of implementation depending on the commutation angle. (Sensorless control of high-speed PM BLDC motor using method based on phase-to-phase voltages).

Design and Control of Disc PMSM Directly Driven Wheel for Tramcar

A new solution of disc permanent magnet synchronous motor (PMSM) directly driven wheel is proposed as a design customized for low floor tramcar. And the motors are overhung on the bogie frame to make the weight as the sprung mass. Meanwhile, the universal coupling is installed between the driven wheel and motor shaft. A disc PMSM is designed according to the demand of traction power. The motors are not only traction and steering actuators but are also regarded as sensors to obtain the rotational speed of motor directly driven wheel. Through the obtained data, an active sensorless steering control method is applied using the relative rotational speed between wheel pair. Finally, models combined with motor control and steering control are set up to check the control strategies. The simulation results indicate that sliding mode observer has the functionality of estimating the rotating speed with high accuracy for active steering control. The tramcar exhibits self-steering and better negotiation under active steering control. The tramcar is under a better condition of running along the central line of track with small attack angle and low power consumption while passing the shape curve track.