Sensorless Control Technique Research Articles

Estimation of PMSM Magnetic Saliency Using Injection Technique

The permanent magnet synchronous motor (PMSM) has very attractive properties such as: high dynamics, small size, high efficiency, low maintenance, small size and mass to power ratio, which make it suitable for the use in industrial drives. In particular its higher efficiency means that PMSM may be used in applications where the energy savings compensate the higher initial cost. For the best utilization of PMSM properties is very important to use some of modern control techniques. But the techniques require information about rotor position. Rotor position measurement is performed using sensors that are expensive and mainly reduce the reliability of the drive. This fact is the reason for interest in sensorless control techniques. In the article, emphasis is placed on sensorless control of PMSM using voltage signal injection, which requires magnetic saliency of the machine. Magnetic saliency and machine suitability for sensorless control using injection methods can be determined in advance using a measurement method whose mathematical analysis is presented in the article. The measurement method was simulated using software product Matlab-Simulink and experimentally verified on a laboratory stand with the AC drive. DOI: http://dx.doi.org/10.5755/j01.eee.20.2.4784

二関節マニピュレータの関節角度センサレス制御

This paper introduces an implementation technique of sensor-less control on two joint robot manipulator. A great number of robots have been developed and most of them mount many kinds of sensors. However, use of the many sensors increase cost of robots and decrease reliance. Shimada et.al. have presented a unique sensorless control technique for electric motor driven mechanical systems. The feature of the technique is to mount mechanical springs on joints of robots. Furthermore, they have tried to extend the sensorless control technique to robots with revolutional joints. However, the performance of the presented observer was not enough to practical use. To fix the problem, we have tried to design time varying observer considering the time varying characteristics on the mounted mechanical springs. This paper introduces the simulation and experimental results of the presented control technique.

G-P-2 確率共鳴を用いたサーボモータの力センサレス化

In this paper, force sensor-less servo control technique for haptic interfaces using stochastic resonance is proposed. The haptic interface developed in this research consists of an AC servo motor with a ball screw. For estimation of applied force, Reaction Force Observer is employed. Since the ball screw structure has high viscosity, response of the force estimation is not suitable for practical industrial application. In this paper, to improve the system responsiveness, servo control system with stochastic resonance is proposed. Finally, several experiments show the effectiveness of the stochastic resonance.

입력전압을 감지하지 않는 전류연속/임계동작모드 Active Power Factor Correction Circuit

본 논문에서는 입력전압을 감지하지 않는 전류연속/임계동작모드 active power factor correction(PFC) circuit을 제안하였다. 기존의 입력전압을 감지하지 않는 PFC circuit의 경우 출력전류가 낮은 경 부하 조건에서 DCM 동작을 수행하고, 이에 따라 PF가 감소하는 문제가 발생한다. 제안한 PFC circuit은 70KHz의 주파수로 CCM 동작을 수행하고, 경 부하 조건에서 최대 200KHz까지 스위칭 주파수가 가변되는 CRM 동작을 수행하도록 하였다. 이를 통해 경 부하 조건에서 PF가 감소하는 문제를 해결하였다. PFC controller IC는 0.35μm BCDMOS 공정을 이용하여 제작하였으며, 240W급 PFC prototype을 제작하여 실험하였다. 제안한 PFC circuit은 기존의 PFC circcuit 대비 최대 10%의 역률이 향상되었고, IEC 61000-3-2 Class D 규격에 따른 경 부하 조건에서는 최대 4% 역률이 향상되었다.

Enhancing the flux estimation based sensorless speed control for switched reluctance machines

This paper deals with the sensorless control of switched reluctance machines (SRMs) using the well-known stator flux estimation based technique.The novelty of this paper is the fact that the entire power electronics converter is deeply characterized and the actual voltage applied to the machine is much more accurately estimated. With such power converter nonlinearities compensation, a remarkable impact (larger when lower the SRM voltage) in the stator flux estimation and the sub consequent quality in the angle estimation are clearly achieved. Therefore, the speed range of this sensorless control technique is enlarged towards to the low speed limit.Experimental results are reported, confirming the overall sensorless control good performance for different load and low speed operating conditions.

Development of 5-axis polishing machine capable of simultaneous trajectory, posture, and force control

The buffing process for finishing an automobile's body is still done manually, and the final surface quality of the body depends on the skill and technique of the worker. To automate buffing, not only tool path control but also precise and fast force control is required. In this study, a novel methodology based on the sensor-less force control technique and the quarry matrix capable of the mode decoupling is proposed for a parallel mechanism polishing machine to control x–y trajectory, tool posture, and polishing force in z-direction, and its validity for automated buffing is verified.

Simplified Modeling, Analysis and Simulation of Permanent Magnet Brushless Direct Current Motors for Sensorless Operation

Problem statement: In this study, a simplified modeling and experimental analysis of Permanent Magnet Brushless DC (PMBLDC) motors for Sensorless operation using MATLAB/SIMULINK. This model provides a mechanism for monitoring and controlling the voltage, current, speed and torque response. Approach: BLDC motor is modeled as sub-blocks. The inverter and switching function are implemented as S-function builder block. The Sensorless scheme employs direct back emf based zero crossing detection technique. Results: The proposed model with Sensorless control technique with back emf zero crossing detection is tested in the BLDC Motor and the performance was evaluated. The simulated and experimental results show that the proposed modeling works quite well during starting and running conditions. Conclusion/Recommendation: The developed model consists of several independent sub-blocks, that can be used in the modeling of Permanent Magnet Sinusoidal Motor and induction motor. Hence the developed simulation model is a design tool to study the dynamic behavior of Sensorless Controlled Brushless DC Motor.

Low-amplitude Carrier Signal Injection-based Techniques for Sensorless Control of Permanent Magnet Drives

Several sensorless vector control schemes able to continuously operate at low and zero speed are based on carrier signal injection. Unfortunately, due to unwanted interactions between transient current components and the carrier signals, a strong high-frequency signal must be injected to accomplish correct estimations. Injection of an intense additional signal causes extra power losses and acoustic noise while resulting in a poor exploitation of the DC bus voltage. After a description of the mechanisms that generate such a phenomenon, this article discusses the real and effective levels of signal amplitude needed during transients and presents a new approach to overcome any interaction and reduce the high-frequency injection. The proposed method is confirmed by experimental tests.

Research of the Measurement Technique for the DC Motor Sensorless Control

Back-EMF zero-crossing detection can detect motor rotor position. The motor start-up problem of sensorless detection technique motor is researched. A novel three-stage start-up method is proposed to solve the problem. And it can ensure Security and reliability of motor start-up and controllability of motor rotation. There is actual theoretical basis for implementing measurement control system for the DC motor sensorless control.

Experimental Evaluation of Position Sensorless Control on Hybrid Electric Vehicle Applications

In this paper, the feasibility of applying a position sensorless control technique to hybrid electric vehicles (HEVs) is practically evaluated. The proposed position estimator has a straightforward structure with properties that combines the model and the saliency tracking-based rotor position estimation for interior permanent magnet synchronous motors (IPMSMs). The proposed method can be used in the event of sensor loss or sensor recovery to sustain continuity of operations. The developed system takes into account the estimated position transition between two distinct sensorless methods. The transition is enhanced by introducing a synchronized transition algorithm based on a single tracking observer. Extensive experimental results are presented to verify the principles and show a reliable estimation performance over the entire speed range including standstill under 150% load conditions.

Ringed-Pole Permanent-Magnet Synchronous Motor for Position Sensorless Drives

A new configuration of surface-mounted permanent-magnet motor in which a copper turn has been wound around each pole is investigated. The purpose is to modify the high frequency direct axis inductance, without affecting the quadrature axis one, creating a rotor high frequency anisotropy. Therefore, position sensorless control technique exploiting the anisotropic rotor features by injecting high frequency signals can be used. After describing the machine structure, the main equations dealing with the rotor dynamic anisotropy are identified. The sensorless control technique is then discussed and expected drive sensorless performance is validated by simulation and experimental results.

Impact of Saturation, Current Command Selection, and Leakage Flux on the Performance of Sensorless-Controlled Three-Pole Active Magnetic Bearings

This paper analyzes two types of effects caused by the fundamental current in saliency-tracking-based techniques for sensorless control of three-pole active magnetic bearings, i.e., saturation and insufficient spectral separation of the fundamental current command during transients. Injection of a high-frequency signal superimposed to the fundamental excitation providing active control allows the measurement of changes in the air gap, from which an estimation of the rotor position can be obtained. Interference of the fundamental current, which is needed to operate the magnetic bearing, with the high-frequency current can occur through two mechanisms: 1) saturation; and 2) high-frequency harmonics caused by fast transients of the fundamental current. Both phenomena can interfere with the sensorless control resulting in a decrease in its performance. The effects caused by the fundamental current on the negative-sequence high-frequency current, used as a position estimation signal, are studied, and a decoupling mechanism is proposed. An analysis of high-frequency leakage flux is presented. and a simple analytical model is developed for describing the aforementioned phenomena. Finite-element analysis of the magnetic bearing under fundamental excitation, as well as experimental verification, is used to validate the analytical findings.

Sensorless Control of Three-Pole Active Magnetic Bearings Using Saliency-Tracking-Based Methods

This paper proposes the use of saliency-tracking-based techniques for sensorless control of three-pole active magnetic bearings. Changes in the air gap resulting from misalignment between stator and rotor axes result in an unbalance in the stator electromagnetic circuit. Injection of a high-frequency signal voltage, which is superimposed to the fundamental excitation providing active control, allows measurement of the unbalance from which an estimation of the rotor position can be obtained. Two different signals are studied for this purpose: 1) negative-sequence high-frequency current and 2) zero-sequence high-frequency voltage. This paper develops analytical models of three-pole magnetic bearings, both for control and for position estimation, which are evaluated through experimental analysis.

Observerless Scheme for Sensorless Speed Control of PMSM Using Direct Torque Control Method With LP Filter

In this study, direct torque control (DTC) of a permanent magnet synchronous motor is realized with a sensorless speed control technique without using an observer. Space vector pulse w ...

Universal Parameter Measurement and Sensorless Vector Control of Induction and Permanent Magnet Synchronous Motors

Recently, induction motors (IMs) and permanent-magnet synchronous motors (PMSMs) have been used in various industrial drive systems. The features of the hardware device used for controlling the adjustable-speed drive in these motors are almost identical. Despite this, different techniques are generally used for parameter measurement and speed-sensorless control of these motors. If the same technique can be used for parameter measurement and sensorless control, a highly versatile adjustable-speed-drive system can be realized. In this paper, the authors describe a new universal sensorless control technique for both IMs and PMSMs (including salient pole and nonsalient pole machines). A mathematical model applicable for IMs and PMSMs is discussed. Using this model, the authors derive the proposed universal sensorless vector control algorithm on the basis of estimation of the stator flux linkage vector. All the electrical motor parameters are determined by a unified test procedure. The proposed method is implemented on three test machines. The actual driving test results demonstrate the validity of the proposed method.

Effectiveness of Voltage Error Compensation and Parameter Identification for Model-Based Sensorless Control of IPMSM

A sensorless-control technique for improving the performance of interior permanent-magnet synchronous-motor control such as the operating speed range and position estimation accuracy is proposed herein. The method presented is based on the estimation of an extended electromotive force in a rotating reference frame. The difference between the reference voltage and the actual voltage of the inverter is modeled and compensated for in order to improve the accuracy and the stability of the sensorless drive system. Moreover, an online parameter-identification technique is applied in order to improve the accuracy of position estimation. The effects of the proposed scheme are evaluated by the experimental results.

Singular Perturbation Theory for DC–DC Converters and Application to PFC Converters

Many control schemes for DC-DC converters begin with the assertion that inductor currents are ldquofastrdquo states and capacitor voltages are ldquoslowrdquo states. This assertion must be true for power factor correction (PFC) converters to allow independent control of current and voltage, and is important for many other applications. In the present study, singular perturbation theory is applied to two-state switching-power converters to provide rigorous justification of the timescale separation. Krylov-Bogoliubov-Mitropolsky averaging is used to include switching ripple effects. A relationship between inductance, capacitance, load resistance, and loss resistances derives from an analysis of the off-manifold dynamics of an approximate model. Similar results hold for boost, buck, and buck-boost converters. Experimental boost converters validate the results. Discrete-time analysis is also shown. Simulated PFC converters demonstrate a simple, sensorless control technique that requires timescale separation.

A Novel Position Sensorless Control of a Four-Switch, Brushless DC Motor Drive Without Phase Shifter

This paper presents the analysis, design, and implementation of a cost-effective sensorless control technique for a low-cost four-switch, three-phase inverter brushless dc motor drive. The proposed sensorless technique is based on the detection of zero crossing points (ZCPs) of three voltage functions that are derived from the filtered terminal voltages nuao and nubo. Six commutation instants are provided that coincide to ZCPs of voltage functions. Hence, there is no need for any 30deg or 90deg phase delay that is prevalent in conventional sensorless methods. Two low-pass filters are used for elimination of high-frequency noises and calculation of average terminal voltages. Also, a direct phase current control method is used to control the phase currents in the four-switch inverter. An analytical study on position estimation error is discussed, and a correction method for some typical applications is suggested. The performance of the developed sensorless technique is demonstrated by simulation, and then, it is implemented using TMS320LF2407A DSP. Experimental results are provided to confirm the simulations.

A Position Sensorless Control System of SRM over Wide Speed Range

This paper presents a position sensorless control system of SRM over wide speed range. Due to the doubly salient structure of the SRM, the phase inductance varies along with the rotor position. Most of the sensorless control techniques are based on the fact that the magnetic status of the SRM is a function of the angular rotor position. The rotor position estimation of the SRM is somewhat difficult because of its highly nonlinear magnetizing characteristics. In order to estimate more accurate rotor position over wide speed range, Neural Network is used for this highly nonlinear function approximation. Magnetizing data patterns of the prototype 1-hp SRM are obtained from locked rotor test, and used for the Neural Network training data set. Through measurement of the flux-linkage and phase currents, rotor position is able to estimate from current-flux-rotor position lookup table which is constructed from trained Neural Network. Experimental results for a l-hp SRM over 16:1 speed range are presented for the verification of the proposed sensorless control algorithm.

Comparison of PM Motor Structures and Sensorless Control Techniques for Zero-Speed Rotor Position Detection

The rotor position of a synchronous permanent magnet (PM) motor can be detected by means of the injection of a high-frequency stator voltage superimposed to the fundamental component. Thanks to the rotor anisotropy, the corresponding high-frequency current is modulated and used to determine the rotor position. Two techniques are considered: the first one adopts a pulsating voltage vector in the estimated synchronous reference frame, while the second one adopts a rotating voltage vector. These techniques are effective at zero and at low motor speed. The accuracy of the rotor position detection depends strictly on the rotor saliency, that is, on the geometry of the PM rotor. In fact both saturation and d-and q-axis cross-coupling have a heavy influence on the correct rotor position detection. The aim of this paper is to compare the two sensorless control techniques, together with two rotor geometries, that is, IPM and inset rotor. In order to highlight the effectiveness of the sensorless technique, the tests are carried out at various operating conditions. It is found that the effectiveness of the sensorless rotor position detection strongly depends on the PM rotor geometry. Conversely, the choice of the sensorless control technique affects slightly the rotor position detection.