A sensorless PMSM drive operating in the field weakening region using only one current sensor

High performance operation of a sensorless Permanent magnet synchronous motor (PMSM) drive demands accurate tuning of controller and observer parameters. This paper presents an Extended Kalman filter (EKF) based sensorless PMSM drive, wherein the dynamic performance of the closed loop controlled drive is enhanced from the dual perspective of the controller and the observer. To this effect, a modification of the speed controller is proposed to reduce the overshoot in speed which is otherwise present while using a conventional PI controller. The performance of the EKF observer is improved by a simple adaptive tuning, which effects fast dynamic response in speed estimation while providing better noise rejection in the steady state operation of the drive. The proposed techniques are validated using simulation and experiment, and results are presented for a Voltage Source Inverter fed 1.5 kW sensorless PMSM drive.

In this paper, the inductance of a sensorless PMSM (Permanent Magnet Synchronous Motor) drive system equipped with a periodic load torque compensator based on a wavelet denoising and least-order observer with time-delay compensation is estimated in real-time. In a sensorless PMSM system with constant load torque, the magnetically saturated inductance value remains constant. This constant inductance error causes minor performance degradation, such as a constant rotor position estimation error and non-optimal torque current, but it does not introduce a speed estimation error. Conversely, in a sensorless PMSM motor system subjected to periodic load torque, the magnetically saturated inductance error fluctuates periodically. This fluctuation leads to periodic variations in both the estimated position error and the speed error, ultimately degrading the load torque compensation performance. This paper applies the maximum energy-to-Shannon entropy criterion for the optimal selection of the mother wavelet in the wavelet transform to remove the motor signal noise and achieve more accurate inductance estimation. Additionally, the coherence and correlation theory is proposed to address the time delay in the least-order observer and improve the time delay. A self-saturation compensation method is also proposed to minimize periodic speed fluctuations and improve control accuracy through inductance parameter estimation. Finally, experiments were conducted on a sensorless PMSM drive system to verify the inductance estimation performance and validate the effectiveness of vibration reduction.

In this paper, normalised state vectors are used to demonstrate the state equations of Extended Kalman Filter (EKF) based sensorless Permanent Magnet Synchronous Motor (PMSM) drive. Based on the normalised EKF equations, Simple Genetic Algorithm (SGA) is employed to optimize the noise covariance and weight matrices of EKF parameters, which thereby reduces the parameter adjusting time and ensures stability of filters in estimations of position and speed. The simulations for SGA training are carried out by MATLAB/Simulink. The experimental sensorless drive system employing Field Oriented Control (FOC) method and SGA is implemented on STM32F103. The simulating and experimental results indicate the effectiveness of the proposed method.

Industrial sensorless permanent magnet synchronous motors (PSM) working at minimum speed of about 10 % of rated speed have been in use for some years. However, PSM drives with high static and dynamic quality down to standstill have just started to be in use in industry. This paper presents a description of the properties of PSM drives using the INFORM® method for sensorless zero-speed control even for torque-, speed and even position-controlled applications. It is shown that the method is able to ensure highly transient operation even at high torque (up to a few times of rated torque) in the low-speed range. Evaluating the statistical properties of the method [Figs. 5, 7] yields probabilities of failures during the lifetime of the drive depending on the “INFORM quality” of the PSM as well as on the dynamic load properties of the application. An industrial example shows the advantageous application of the method in a position-controlled series application.

This paper compares some sensorless Permanent Magnet Synchronous Motor (PMSM) controls for driving an electric vehicle in terms of operating speed. Sensorless control is a type of control method in which sensors, such as speed and position sensors, are not used to measure controlled variables. The controlled variable value is estimated from the stator current measurement. Sensorless control performance is not as good as a sensor-based system. This paper aims are to recommend a control method for the PMSM sensorless controls that would be used to drive an electric vehicle. The methods that we will discuss are divided into four categories based on the operation speed area. They are a startup, low speed, high speed, and low and high-speed areas. The low and high-speed area will be divided into with and without switching. If PMSM more work at high speed, the most speed area that is used, we prefer to choose the method that works at high speed, that is, the modification or combination of two or more conventional methods.

A new instantaneous torque-control strategy is presented for high-performance control of a permanent magnet (PM) synchronous motor. In order to deal with the torque pulsating problem of a PM synchronous motor in a low-speed region, new torque estimation and control techniques are proposed. The linkage flux of a PM synchronous motor is estimated using a model reference adaptive system technique, and the developed torque is instantaneously controlled by the proposed torque controller combining a variable structure control (VSC) with a space-vector pulse-width modulation (PWM). The proposed control provides the advantage of reducing the torque pulsation caused by the nonsinusoidal flux distribution. This control strategy is applied to the high-torque PM synchronous motor drive system for direct-drive applications and implemented by using a software of the digital signal processor (DSP) TMS320C30. The simulations and experiments are carried out for this system, and the results demonstrate the effectiveness of the proposed control.

This paper presents a speed and position sensorless permanent magnet synchronous motor (PMSM) drive using simple and robust model reference adaptive control (MRAC) for light electric vehicle (LEV) application. The sensorless speed and position estimator consists the flux and torque based MRAC, which improves the performance during dynamic as well as steady state condition for wide range of speed operation. Mostly, PMSM drive uses field oriented control for the closed loop speed control operation. Generally, PI controller is used speed and current controller. However, the PI controller gain requirement often changes during various driving conditions of the vehicle. Therefore, this work is focused to eliminate fixed gain PI controller by utilizing online self-tuned PI speed controller and PMSM model based predictive current controller. The self-tuning approach of PI controller for the speed control loop uses the principle of adaptive interaction, which performs tuning by minimizing error objective function. The predictive current controller eliminates the need of modulator and incorporates the inverter nonlinearities. In addition to this, the sensorless approach reduces the complexity and cost of the drive. The combined system of improved controllers and sensorless estimator improves the drive performance for wide range of speed operation.

For the position sensorless permanent magnet synchronous motor (PMSM) drive system, the online identification of temperature is of great significance for safe operation. Generally, the motor temperature can be obtained directly from the stator resistance, the identification of which is, however, affected by the position estimation error of sensorless control. In order to deal with this problem, a stator temperature identification method for the interior PMSM is proposed with the position error adaptive compensation. The influence of position error on the stator resistance and temperature identification is analyzed and then compensated based on the minimum current vector online tracking (MCVOT) scheme for improving the identification precision. For further improving the accuracy and the convergence rate of MCVOT, a current vector angle tracking strategy based on the adaptive variable tracking step value is adopted in the rotating reference frame. The validity of the proposed method is verified on two experimental platforms.

Recurrent modified Elman neural network control of PM synchronous generator system using wind turbine emulator of PM synchronous servo motor drive

This paper deals with theoretical analysis and design of permanent magnet (PM) synchronous motors (PMSMs) with minimized cogging force. Recently, many optimal designs for the PMSMs have been done by finite element (FE) analysis, but such analysis generally is time consuming. In this study, the equation of magnetic flux lines existing between PMs and iron cores is expressed geometrically and the cogging force is calculated theoretically without FE analysis. The form of equation is assumed to be the second-order polynomial and the virtual core is used to express the cogging force in analytical model. The cogging force can be calculated by applying the solved flux line equation and the flux density equation to the Lorentz force equation by using the Maxwell stress tensor. The theoretical analysis of minimized cogging force is applied to several prototypes such as synchronous PM planar motor (SPMPM), 2-DOF PMSM with screw motion, and axial flux PM (AFPM) brushless dc motor in this paper, and the analytical results are validated by FE analyses and experiments.

There has recently been considerable interest in using the sensorless permanent magnet synchronous motor (PMSM) for vehicle propulsion systems. While many sensorless PMSM techniques have been presented in the literature, few have discussed in detail the underlying hardware and implementation issues. This work focuses on the implementation and application of a sensorless PMSM strategy that is particularly well suited for vehicle propulsion systems. The selected sensorless PMSM technique is implemented in a real-time motor control system to form a sensorless electric drive prototype. The hardware, strategy and implementation issues associated with the development of the sensorless drive are discussed. Experimental results are included in order to demonstrate the robustness of the implementation and the effectiveness of the sensorless drive under transient operating conditions such as startup and speed reversal.

This report provides background information on various fractional-horsepower electric motor technologies used for evaporator fan applications in commercial refrigeration and summarizes data from a DOE-sponsored evaporator fan motor laboratory and field demonstration project. This report also extrapolates that data to project the potential economic and environmental benefits resulting from upgrading the current installed base of commercial refrigeration evaporator fan motors to permanent magnet synchronous (PMS) motors.Evaporator fan motors used in commercial refrigeration applications are fractional horsepower in size, responsible for moving air across the evaporator coil, and typically run at one speed. Historically, shaded-pole induction motors have been the most commonly used evaporator fan motors in commercial refrigeration equipment and beverage vending machines. These are the simplest and least expensive type of fractional-horsepower motor, with an efficiency of approximately 20%. Electronically commutated (EC) permanent magnet motors, also known as brushless DC motors, were initially commercialized in the late 1980s, and their use in commercial refrigeration applications has increased within the last 10 to 15 years because of economic incentives and regulatory requirements. State-of-the-art EC motors are approximately 66% efficient. Another induction motor type, the permanent split capacitor (PSC) motor, offers a mid-point between shaded-pole and EC motor price and efficiency levels. PSC motors are typically about 29% efficient.A permanent magnet synchronous (PMS) AC motor that can directly use grid-supplied AC current without the need to rectify to DC has recently been commercialized. This new motor exhibits a peak efficiency of 75% and has the potential to significantly reduce the energy consumption of evaporator fan motors in commercial refrigeration equipment. Laboratory evaluation of evaporator fan motor technologies was performed to quantify and compare the performance of shaded-pole, PSC, EC, and PMS evaporator fan motors in a controlled environment, so as to minimize the influence of external factors and anomalies. The laboratory evaluation included dynamometer testing of the fan motors and airflow testing of the motor/fan assemblies. It was found that the 6–12 W PMS motor exhibited a peak efficiency of 75% with a power factor of approximately 0.9 at a power output of 11 W. It was also found that a 38–50 W PMS motor exhibited a peak efficiency of 82% with a power factor of approximately 0.9 at a power output of 35 W.Airflow testing of shaded-pole, PSC, EC, and PMS motor/fan assemblies was performed using an airflow test chamber, which was designed in accordance with ANSI/AMCA Standard 210-16/ASHRAE Standard 51-16, to measure the performance of the subject motor/fan assembly and to determine the incumbent display case system impedance (AMCA 2016). A family of fan curves (static pressure vs airflow rate and electrical power input vs airflow rate) was generated for the 6–12 W PMS motor/fan assemblies with 8-inch fan blades pitched from 17 to 32 degrees. A similar set of curves was generated for the 38–50 W motors paired with 10 and 12-inch blades. Various incumbent motor/fan assemblies were also tested in the laboratory airflow test chamber and their fan curves were generated.Field evaluation of refrigerated display case evaporator fan motors was accomplished by performing side-by-side comparisons of 6–12 W PMS motors to 6–12 W shaded-pole and EC evaporator fan motors. It was found that, on average, a PMS motor consumes 79% less power and draws 82% less current than a shaded pole motor, and on average, 34% less power and 49% less current than an EC motor. In addition, the PMS motor exhibits an average power factor of approximately 0.82, which is on average 40% greater than that of existing evaporator fan motors.Two field test sites were selected to evaluate the performance of the larger 38 to 50 W PMS evaporator fan motors in walk-in cooler/freezer applications. At each supermarket, two walk-in units were selected for investigation: one walk-in dairy cooler and one walk-in freezer. A 61% decrease in fan motor power was measured when retrofitting existing evaporator fan motors with PMS motors in the walk-in cooler. In addition, a 48% decrease in fan motor power was measured when retrofitting existing evaporator fan motors with PMS motors in the walk-in freezer.The culmination of the field evaluation of fan motor technologies was a whole-store retrofit conducted at a supermarket. Pre- and post-retrofit measurement of evaporator fan motor power in medium- and low-temperature refrigerated display cases and walk-in coolers/freezers was performed. Overall for the whole-store retrofit, the current supplied to all monitored evaporator fan motors was reduced by 52%, the real power was reduced by 46% and the apparent power was reduced by 51% following the retrofit of the 262 evaporator fan motors that w

Field-weakening mode of operation is an important feature of modern permanent magnet (PM) synchronous electrical drives, which overcomes speed limitation due to the lack of supplying voltage and increases their speed operational range. Therefore, field-weakening (FW) algorithm is an inalienable part of the overwhelming majority of control systems for PM synchronous motors. At the same time, seamless integration of the filed-weakening techniques into the conventional control systems is not considered well and some reported solutions may decrease system reaction time and cause stability issues. This paper proposes an improved field-weakening strategy, which includes optimized FW controller and novel current limitation strategy in the field-weakening mode. These features simplify structure of the resulting control scheme, decrease computational burden on the microcontrollers and decreases system reaction time, caused by wind-up of the speed controller operating in parallel with the conventional FW algorithms.

One of the main reasons for adopting the field oriented controlled (FOC) induction machine for high performance application is its capability for easy implementation in field weakening. In a sensorless FOC induction machine, the speed estimation in Field Weakening (FW) region and the sensitivity to parameter error of the motor is a major problem. Model Reference Adaptive System (MRAS) approach is one of the best techniques to estimate the rotor speed due to its straight forward stability approach. Space vector pulse width modulated (SVM) voltage source inverter is preferred to feed the FOC induction machine rather than the traditional sinusoidal pulse width modulated (SPWM) inverter due to the full utilization of voltage and current rating of the inverter. In this paper, a sensorless FOC induction machine with MRAS scheme based on sliding mode (SM) technique to estimate the rotor speed in the FW region using SVM fed inverter is modeled. The drive system is simulated by MATLAB/Simulink and the performance of the technique is evaluated by comparing the model with FOC induction machine with sensor using SVM inverter.

This paper deals with the dSPACE DS1103 based implementation of a simplified fuzzy logic speed controller (Simplified FLSC) for vector controlled permanent magnet synchronous motor (PMSM) drives. The simplification of FLSC obtains minimization and adjustment of the membership function used by each fuzzy variable for the drive system. The mathematical model of PMSM drives has been simulated in the MATLAB environment using Simulink and Fuzzy Logic Toolbox to analyze the performance of the drive system. The simulated results are then validated with the experimental investigation. For experimentation, the FLSC, co-ordinate transformation and hysteresis current controller (HCC) have been implemented in MATLAB environment with Simulink, Fuzzy Logic Toolbox and Real-time interface. Meanwhile, the hardware implementation consisting of dSPACE digital signal processor, voltage source inverter, resolver-to-linear DC converter, current sensors and PMSM equipped with speed resolver. The PMSM drive system has been tested under various operating conditions and load disturbances.