Lyapunov-function-based flux and speed observer for AC induction motor sensorless control and parameters estimation

AC induction motors have become very popular for motion-control applications due to their simple and reliable construction. Control of drives based on ac induction motors is a quite complex task. Provided the vector-control algorithm is used, not only the rotor speed but also the position of the magnetic flux inside the motor during the control process should be known. In most applications, the flux sensors are omitted and the magnetic-flux phasor position has to be calculated. However, there are also applications in which even speed sensors should be omitted. In such a situation, the task of state reconstruction can be solved only from voltage and current measurements. In the current paper, a method based on deterministic evaluation of measurement using the state observer based on the Lyapunov function is presented. The method has been proven in testing on a real ac induction machine.     

Four-quadrant position sensorless control in SRM drives over the entire speed range

Proper synchronization of the excitation with respect to the rotor position is essential in optimal control of switched reluctance motor (SRM) drives. To avoid additional cost, size, and unreliability caused by the external position sensors, magnetic status of the SRM can be directly monitored to detect commutation instants. A one-to-one correspondence between magnetic status of the SRM and rotor position removes the need for an explicit access to the rotor position. In order to obtain a good precision over the entire speed range, educated modifications on the structure of the sensorless strategy is necessary. This is due to the impact of the operational regions on dynamic behavior of the SRM. In addition, introduction of SRM technology to industrial and domestic applications has raised the need for four-quadrant operation of the SRM drives. The present paper introduces a range of strategies that are necessary to accommodate this requirement in a sensorless format. Our experimental findings indicate that high-grade sensorless operation in a four-quadrant SRM drive is possible and can be integrated in a variety of applications.     

Design of a sensorless commutation IC for BLDC motors

This paper presents the design and realization of a sensorless commutation integrated circuit (IC) for brushless DC motors (BLDCMs) by using mixed-mode IC design methodology. The developed IC can generate accurate commutation signals for BLDCMs by using a modified back-EMF sensing scheme instead of using Hall-effect sensors. This IC can be also easily interfaced with a microcontroller or a digital signal processor (DSP) to complete the closed-loop control of a BLDCM. The developed sensorless commutation IC consists of an analog back-EMF processing circuit and a programmable digital commutation control circuit. Since the commutation control is very critical for BLDCM control, the proposed sensorless commutation IC provides a phase compensation circuit to compensate phase error due to low-pass filtering, noise, and nonideal effects of back-EMFs. By using mixed-mode IC design methodology, this IC solution requires less analog compensation circuits compared to other commercially available motor control ICs. Therefore, high maintainability and flexibility can be both achieved. The proposed sensorless commutation IC is integrated in a standard 0.35-/spl mu/m single-poly four-metal CMOS process, and the realization technique of this mixed-mode IC has been given. The proposed control scheme and developed realization techniques provide illustrative engineering procedures for the system-on-a-chip solution for advanced digital motor control. Simulation and experimental results have been carried out in verification of the proposed control scheme.     

Automatic flux-weakening control of permanent magnet synchronousmotors using a reduced-order controller

This study presents a novel means of designing a simple and effective position and velocity controller for permanent magnet synchronous motors (PMSM). In contrast to the conventional two-loop control methods with full-state feedback, the proposed controller does not need current information of the motor for feedback purposes. However, under normal operation the steady-state d-axis current can still be controlled to zero to minimize power dissipation. In addition, implementing a simple overmodulation strategy allows the controller to automatically generate a flux-weakening control to expand the range of operating speed when voltage saturation occurs. In addition to not depending on system parameters used by the controller, the automatically generated demagnetizing current is also optimal in the sense of minimum power dissipation that differs from the maximum output torque design or the constant power design of the general flux-weakening control methods. Simulation and experimental results show that the controller can achieve an effective speed and position control with near-minimum power dissipation, even when voltage saturation occurs     

A new torque and flux control method for switched reluctance motordrives

Switched reluctance (SR) motors have an intrinsic simplicity and low cost that make them well suited to many applications. However the motor's doubly salient structure and highly nonuniform torque and magnetization characteristics lead to the inability to excite the motor using conventional AC motor waveforms, or apply established AC motor rotating field theory to the motor. Furthermore, high torque ripple is inherent in the motor unless a torque ripple reduction strategy is employed. Thus, control of the motor is difficult and complex compared to other machines. Previous methods of control have fallen into two main categories: those which use a simplified linear model and those which account for the motor saturation. The simplified linear model schemes have the advantage of simplicity and tractability but are inaccurate in most practical SR drives, whereas the nonlinear schemes have the problem of high complexity and computational expensiveness which makes real-time implementation difficult. To overcome these problems, in this paper, a novel control method for the SR motor is derived from analysis of the nonuniform torque characteristics of the motor. The control method applies the philosophy of direct torque control (DTC). Unlike previous direct torque control schemes for the SR motor drive, the new method does not involve short flux patterns, a change of the motor winding configuration, or the use of a bipolar current drive. Thus, the scheme can be conveniently implemented on any normal type of SR motor drive. In addition, the scheme overcomes the problems associated with torque ripple control in the SR motor by regulating the torque output of the motor within a hysteresis band. Furthermore, the scheme is very simple and can be implemented in real-time with low cost microprocessor hardware     

Sensorlose Drehzahl- und Lageregelung von Permanentmagnet-Synchronmaschinen auf Basis des INFORM-Verfahrens

This paper deals with the operation of permanent magnet synchronous motors without speed- and position sensors in speed- and position-controlled drive applications. Starting from classical field-oriented control methods, a speed-sensorless drive is presented. The basic idea is to estimate the actual speed and position of the drive by means of the INFORM method (low speed and standstill) and EMF-based models (high speed). Measurements on a position-controlled industrial system verify the high quality of the sensorless system which reduces the hardware costs of the drive and increases the reliability by eliminating mechanical components.     

Detection of Rotor Position in Stepping and Switched Motors by Monitoring of Current Waveforms

The paper describes new methods of detecting rotor position in stepping and switched motors, with chopper or series-resistance drives, by monitoring winding currents. In contrast to previous methods of waveform detection, the new techniques are reliable over the complete speed range. It is shown that the most useful indicators of rotor position are: i) current rise times arising from chopping an unexcited phase at low current and ii) the initial rate of current rise as a phase is switched on in a series-resistance drive. Implementation is via simple low-cost electronic circuits and the paper includes discussion of how the techniques can be applied to closed-loop stepping motor control, ministep drives, and optimization of step response.     

High robustness and reliability of fuzzy logic based positionestimation for sensorless switched reluctance motor drives

In many applications where motor drives are used, concern. Thus, a major consideration is the reliability of position estimation schemes when sensor less SR motor drive control is employed. Hence, in this paper, the robust of a fuzzy logic based angle estimation algorithm for the switched reluctance motor (SR) motor is described. It is shown using theoretical analysis and experimental results, that by using logic, the angle estimation scheme gains a high level of robustness and reliability. A theoretical and quantitative analysis of the noise and error commonly found in practical motor drives is given, and how this can affect SR motor position estimation. An analysis is also given on the concepts of robustness and reliability. It is shown that the fuzzy logic based scheme is robust to erroneous and noisy signals commonly found in motor drives     

Sensorless position control of a brushless motor in circulatory assist devices

An innovative technique to implement position feedback and commutation of brushless D.C. motors without explicit position sensing is presented. The procedure has been successfully implemented for the Pennsylvania State University Electric Ventricular Assist Device (EVAD). Laboratory tests indicate that the method is successful for pumping operations in a mock circulatory loop for beat rates up to 60 beats min⁻¹ and over several days of uninterrupted operation. This method of sensorless commutation is presently being investigated for inclusion as a backup system for the Penn State circulatory assist devices.     

Design and implementation of a high-speed matrix multiplier based on word-width decomposition

This paper presents a flexible 2/spl times/2 matrix multiplier architecture. The architecture is based on word-width decomposition for flexible but high-speed operation. The elements in the matrices are successively decomposed so that a set of small multipliers and simple adders are used to generate partial results, which are combined to generate the final results. An energy reduction mechanism is incorporated in the architecture to minimize the power dissipation due to unnecessary switching of logic. Two types of decomposition schemes are discussed, which support 2's complement inputs, and its overall functionality is verified and designed with a field-programmable gate array (FPGA). The architecture can be easily extended to a reconfigurable matrix multiplier. We provide results on performance of the proposed architecture from FPGA post-synthesis results. We summarize design factors influencing the overall execution speed and complexity.     

基于FPGA及DDS技术的USM测试电源的设计

超声波电机的运转需要一个两相相差90°（或可调）的高频交流信号源。本方案采用DDS技术的设计思路,用VHDL硬件描述语言对FPGA器件编程产生了两相四路高频信号。该信号经过驱动隔离电路施加于H桥逆变器中,在电感的平滑作用下,生成了满足USM测试要求的可调频、调相、调幅的两相高频交流信号源,成功地对USM45电机进行了驱动测试。该电路可用于研究超声波电机的运行状态的研究及获取其最佳工作点参数。     

Sensorless PM brushless DC motor drives

To control PM brushless DC motors, position and speed sensors are indispensable because the current should be controlled depending on the rotor position. However, these sensors are undesirable from standpoints of size, cost, maintenance, and reliability. There are different ways of approaching this problem, depending on the flux distribution. The paper presents the speed and position sensorless control of PM brushless DC motors with a sinusoidal flux distribution. Two approaches are presented and compared with each other; one is based on the voltage model of the motor and another is based on the current model. The starting procedure is also a very difficult problem under sensorless drives, because the sensorless drive algorithm uses voltage and current for estimation of rotor position, but no information is available before starting. A novel starting method is presented by using a salient-pole machine. Experimental results based on DSP-TMS320C25 controller are shown for comparisons, which demonstrate desired characteristics both in steady-state and starting conditions     

Optimal asymmetrical back plane biasing for energy efficient digital circuits in 28 nm UTBB FD-SOI

In this work we propose an optimal back plane biasing (OBB) scheme to be used in a UTBB FD SOI technology that minimizes the energy per operation consumption of sub threshold digital CMOS circuits. By using this OBB scheme, simulations show that more than 30% energy savings can be obtained with low threshold voltage (LVT) devices in comparison with classic symmetric back plane biasing (SBB) schemes. Additionally, this OBB scheme allows to adjust the performance of the circuit with very small energy penalties. A very simple and intuitive model, for sub threshold digital CMOS circuits, was developed to justify the benefits obtained by OBB. The results predicted by the model are confirmed with extensive simulation results. We show that the OBB approach can be applied easily to a given circuit just based on the information provided by a logic simulation of the circuit (or even an analysis of its structure) and simple electrical simulations of the pMOS and nMOS transistors. Finally, we show that the variability in the energy consumption is improved by using OBB and suggests that new sizing methodologies must be studied to fully benefit from the wide back plane voltage range available in UTBB FD SOI technology for the design of robust energy efficient digital circuits.     

New sensorless vector control using minimum-order flux state observer in a stationary reference frame for permanent-magnet synchronous motors

This paper proposes a new sensorless vector control method that can be applied to both of salient-pole and nonsalient-pole permanent-magnet synchronous motors (PMSMs). The proposed method estimates the phase of a rotor flux by a newly developed state observer in a stationary reference frame for sensorless vector controls of PMSMs. The flux state observer has the following attractive features: 1) it requires no steady-state conditions for the dynamic mathematical model of the motor; 2) its order is the minimum second; 3) a single observer gain is simply constant over a wide operating range and can be easily designed; 4) it utilizes motor parameters in a very simple manner; and 5) its structure is very simple and can be realized at a very low computational load. The proposed speed-estimation method, which exploits the inherent physical relation of integration/derivation between phase and speed, is very simple and can properly estimate rotor speed. The usefulness of the proposed method is examined and confirmed through extensive experiments.     

Experimental Study of a Soft-Switched Isolated Bidirectional AC–DC Converter Without Auxiliary Circuit

An isolated ac-dc converter topology includes a capacitively snubbered voltage source converter (VSC) and a cycloconverter, coupled by a medium frequency transformer. The topology offers the possibility of bilateral power flow as well as three-level pulse width modulation on the ac side. It is shown that by alternately commutating the VSC and the cycloconverter it is possible to achieve either zero-voltage or zero-current switching conditions for all semiconductor devices in all points of operation. This is the case without any need for auxiliary semiconductor devices. At low load the transformer current may be insufficient for recharging the VSC snubber capacitors. In this case, however, it is possible to utilize the cycloconverter for providing a current path by which a quasi-resonant commutation can be made. The design and operation of a 40-kVA prototype converter system is described. It is shown how the rather complex switching logic required for implementing the chosen algorithm for commutation and modulation can be realized by using modern programmable logic devices [field programmable gate array (FPGA)]. Measurement results from the prototype converter are presented and analyzed. The measurements indicate that the studied commutation algorithm works well in practice     

DSP-Based Sensorless Electric Motor Fault Diagnosis Tools for Electric and Hybrid Electric Vehicle Powertrain Applications

The integrity of electric motors in work and passenger vehicles can best be maintained by frequently monitoring its condition. In this paper, a signal processing-based motor fault diagnosis scheme is presented in detail. The practicability and reliability of the proposed algorithm are tested on rotor asymmetry detection at zero speed, i.e., at startup and idle modes in the case of a vehicle. Regular rotor asymmetry tests are done when the motor is running at a certain speed under load with stationary current signal assumption. It is quite challenging to obtain these regular test conditions for long-enough periods of time during daily vehicle operations. In addition, automobile vibrations cause nonuniform air-gap motor operation, which directly affects the inductances of electric motors and results in a noisy current spectrum. Therefore, it is challenging to apply conventional rotor fault-detection methods while examining the condition of electric motors as part of the hybrid electric vehicle (HEV) powertrain. The proposed method overcomes the aforementioned problems by simply testing the rotor asymmetry at zero speed. This test can be achieved at startup or repeated during idle modes where the speed of the vehicle is zero. The proposed method can be implemented at no cost using the readily available electric motor inverter sensors and microprocessing unit. Induction motor fault signatures are experimentally tested online by employing the drive-embedded master processor (TMS320F2812 DSP) to prove the effectiveness of the proposed method.      

Torque-ripple minimization with indirect position and speed sensingfor switched reluctance motors

A torque-ripple-minimization controller is realized along with indirect position and speed sensing for switched reluctance motors (SRMs). The position and speed estimations are derived from a sliding-mode observer that requires terminal measurements of only phase voltages and currents. The research shows that position- and speed-sensorless observers can be reliably used for control of an SRM. Experimental results using a four-phase, 8/6 SRM and the TMS320C30 digital signal processor are presented. The results demonstrate position- and speed-sensorless closed-loop operation of a torque-ripple-minimized SRM drive     

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.     

Sensorless speed control of nonsalient permanent-magnet synchronous motor using rotor-position-tracking PI controller

This paper presents a new velocity estimation strategy of a nonsalient permanent-magnet synchronous motor (PMSM) drive without a high-frequency signal injection or special pulsewidth-modulation (PWM) pattern. This approach is based on the d-axis current regulator output voltage of the drive system that has the information of rotor position error. Rotor velocity can be estimated through a rotor-position-tracking proportional-integral (PI) controller that controls the position error to zero. For zero and low-speed operation, the PI controller gains of rotor position tracking controller have a variable structure according to the estimated rotor velocity. In order to boost the bandwidth of the PI controller around zero speed, a loop recovery technique is applied to the control system. The proposed method only requires the flux linkage of the permanent magnet and is insensitive to parameter estimation error and variation. The designers can easily determine the possible operating range with a desired bandwidth and perform vector control even at low speeds. The experimental results show the satisfactory operation of the proposed sensorless algorithm under rated load conditions.     

Generalized minimum distance decoding on majority logic decodable codes (Corresp.)

Generalized minimum distance decoding schemes are found for majority logic decodable codes. These decoding schemes are parallel to the classical majority logic decoding schemes and thus can be easily implemented.