Constant Torque Region Research Articles

Adaptive Backstepping Control for an Interior Permanent Magnet Synchronous Motor Servo System

This paper presents a nonlinear adaptive backstepping current hysteresis speed controller which can be used in both the constant-torque region and the field-weakening region for an interior permanent magnet synchronous motor (IPMSM). By using the proposed method, the adjustable speed range can be extended to 4 times that of the base speed. In addition, the d-axis current is suitably adjusted to increase the output torque of the IPMSM. Simulation results show that the implemented system has satisfactory performance, including good transient responses, good load-disturbance-rejection responses, and good tracking ability.

Direct Torque Control of Four-Switch Brushless DC Motor With Non-Sinusoidal Back EMF

This paper presents a direct torque control (DTC) technique for brushless dc (BLDC) motors with non-sinusoidal back electromotive force (EMF) using a four-switch inverter in the constant torque region. This approach introduces a two-phase conduction mode as opposed to the conventional three-phase DTC drives. Unlike conventional six-step current and voltage control schemes, by properly selecting the inverter voltage space vectors from a simple look-up table at a predefined sampling time, the desired quasi-square wave current is obtained. Therefore, a much faster torque response is achieved compared to conventional current and voltage control schemes. In addition, for effective torque control, a novel switching pattern incorporating the voltage vector look-up table is designed and implemented for a four-switch inverter to produce the desired torque characteristics. Furthermore, to eliminate the low-frequency torque oscillations, pre-stored back EMF constant versus position look-up tables are designed and used in the torque estimation. As a result, it is possible to achieve two-phase conduction DTC of a BLDC motor drive with faster torque response due to the fact that the voltage space vectors are directly controlled. A theoretical concept is developed and the validity and effectiveness of the proposed DTC scheme are verified through the simulations and experimental results.

Field Weakening Control of IPMSM Based Next Generation High Speed Railway System

In this paper, a vector control of the IPMSM drives for the next generation domestic high speed railway system is presented. The applied control method uses one pulse mode field weakening control in constant power region, and maximum torque control per ampere control in constant torque region considering current and voltage limits. An overmodulation control interval is inserted to improve the transient characteristics during transition period of the control modes. Simulation programs based on Matlab/Simulink are developed. Finally the designed system is verified by simulation and their characteristics are analyzed by the simulation results.

Model reference controlled separately excited DC motor

This research article proposes the speed control of a separately excited DC motor (SEDM) in the constant torque region. The novelty of this article lies in the application of artificial neural network-based model reference controller (MRC) for the speed control of SEDM. This paper also discusses and compares the speed control systems of SEDM using PI-controlled and fuzzy logic-controlled chopper circuit with MRC. The entire system has been modeled using MATLAB 7.0/SIMULINK toolbox. It has been observed that chopper-controlled speed control system could be eliminated by the use of MRC and the performance of the proposed system is comparable with speed control system using chopper circuit.

A simple but high-performance IM speed drive

The paper deals with an induction motor (IM) speed drive having high performance over a large speed range in the constant torque region. The drive is built up around an outer loop of speed equipped with an incremental encoder and two inner loops of torque and flux implemented in a direct torque control (DTC) scheme. The scheme takes advantage of the available speed to estimate the motor torque and the stator flux magnitude by means of the IM current model. This allows the full exploitation of the drive capabilities even in the low speed range. Furthermore, with a suitable representation of the IM current model, the drive can be operated down up to zero speed. The paper closes by analytically investigating the detuned behaviour of the scheme due to a rotor time constant mismatch. Experimental results substantiate the low-speed capabilities of the scheme and the findings on its detuned behaviour.

Flux-Weakening Control of IPM Motors With Significant Effect of Magnetic Saturation and Stator Resistance

In this paper, we propose a systematic optimization approach to flux-weakening control of interior permanent-magnet (IPM) motors, which operate in magnetic saturation. The current commands are chosen to be optimal so as to minimize power loss not only in the constant-torque region but also in the constant-power region. Our approach aims at the same objective as the previously known flux-weakening control. Furthermore, the motor torque of an IPM motor in magnetic saturation can be made exactly linear with respect to the torque command. Thereby, our systematic approach can provide not only maximal power efficiency but also torque linearity. In doing so, we consider a more general situation than that considered in prior literature. Specifically speaking, the physical constraints in stator currents and voltages, and the effect of stator resistance are all taken into full account. As a result, the optimization problem becomes very complicated. Nonetheless, we have successfully found the approximate optimal solution, which can be readily implemented on a usual high-speed microprocessor. The practical effectiveness of the proposed control method is also demonstrated through various simulation and experimental results.

High-Speed Control of IPMSM Drives Using Improved Fuzzy Logic Algorithms

This paper presents an improved fuzzy logic controller (FLC) for an interior permanent magnet synchronous motor (IPMSM) for high-performance industrial drive applications. In the proposed control scheme for high-speed operations above the rated speed, the operating limits of IPMSM are expanded by incorporating the maximum torque per ampere operation in constant torque region and the flux-weakening operation in constant power region. The power ratings of the motor and the inverter are considered in developing the control algorithm. A new and simple FLC is utilized as a speed controller. The FLC is developed to have less computational burden, which makes it suitable for real-time implementation, particularly at high-speed operating conditions. The complete drive is implemented in real-time using digital signal processor (DSP) controller board DS 1102 on a laboratory 1-hp IPM motor. The efficiency of the proposed control scheme is evaluated through both experimental and computer simulation results. The proposed controller is found to be robust for high-speed applications

Nonlinear-controller design for an interior-permanent-magnet synchronous motor including field-weakening operation

The paper proposes a nonlinear adaptive backstepping speed controller which can be used in both the constant-torque region and the field-weakening region for an interior-permanent-magnet synchronous motor. By using the proposed method, the adjustable speed range can be extended to 1.6 times that of the base speed. In addition, the d-axis current is suitably adjusted to increase the output torque of the interior-permanent-magnet synchronous motor. A DSP-based fully digital speed-control system is implemented. The DSP is used to execute the current and the nonlinear speed-loop control algorithms. The implemented system has satisfactory performance, including good transient responses, good load-disturbance-rejection responses, and good tracking ability. Several experimental results validate the theoretical analysis.

Improved dynamic control for permanent magnet AC (PMAC) machine in the field weakening region

AbstractThis paper presents a study of a predictive torque and flux control in the constant torque region and in the field‐weakening one of Permanent Magnet Alternate Machines (PMAC) fed by a Voltage Source Inverter (VSI). It is based on the step‐by‐step determination of the inverter feeding voltage as a function of the current references, by taking into account both the steady state and the transient electrical constraints. Experimental results confirm the validity of the proposed approach and the possibility of achieving very good dynamic performances. Copyright © 2005 John Wiley & Sons, Ltd.

Performance of interior permanent magnet motor drive over wide speed range

This paper investigates the performance of an interior permanent magnet synchronous motor (IPMSM) drive over wide speed range for high precision industrial applications. The scheme incorporates the maximum torque per ampere (MTPA) operation in constant torque region and the flux-weakening operation in constant power region in order to expand the operating limits for an IPMSM. Improved mathematical expressions are derived to analyze the performances of the IPMSM. The power ratings of the motor and the inverter are considered. The effects of motor parameters particularly, the saliency ratio (X/sub q//X/sub d/) on the voltage limit constraint and the power capability of the inverter are also investigated. The efficacy of the above mentioned drive system and the improved steady-state analysis are evaluated by both experimental and computer simulation results. The complete drive is implemented in real-time using digital signal processor (DSP) controller board DS 1102 on a laboratory 1 hp interior permanent magnet synchronous motor.

Performance of Interior Permanent Magnet Motor Drive over Wide Speed Range

This paper investigates the performance of an interior permanent magnet synchronous motor (IPMSM) drive over wide speed range for high precision industrial applications. The scheme incorporates the maximum torque per ampere (MTPA) operation in constant torque region and the flux-weakening operation in constant power region in order to expand the operating limits for an IPMSM. Improved mathematical expressions are derived to analyze the performances of the IPMSM. The power ratings of the motor and the inverter are considered. The effects of motor parameters particularly, the saliency ratio (X/sub q//X/sub d/) on the voltage limit constraint and the power capability of the inverter are also investigated. The efficacy of the above mentioned drive system and the improved steady-state analysis are evaluated by both experimental and computer simulation results. The complete drive is implemented in real-time using digital signal processor (DSP) controller board DS 1102 on a laboratory 1 hp interior permanent magnet synchronous motor.

A novel polyphase multipole square-wave permanent magnet motor drive for electric vehicles

A novel high-power-density permanent magnet (PM) motor drive for electric vehicles (EVs) is proposed. The motor is a polyphase multipole square-wave PM motor, which can be classified as a kind of PM brushless DC motor. The distinct features of the proposed motor as compared to those of the conventional PM brushless DC motor are as follows. First, the multipole magnetic circuit arrangement enables the minimization of the magnetic yoke, resulting in the reduction of motor volume and weight. Second, the coil span is purposely designed to be equal to one slot pitch, thus saving the amount of copper used. Third, by using a fractional number of slots per pole per phase, the arrangement of the numbers of poles and slots is so unique that the magnetic force between the stator and the rotor at any rotating position is uniform, hence eliminating the cogging torque that usually occurs in PM motors. Finally, the motor can be controlled to operate at a constant torque region and a constant power region with field weakening, thus both high starting torque and high cruising speed can be achieved. Therefore, as the proposed motor drive possesses the distinct advantages of high power density, high efficiency, and superior dynamic performance, it is very suitable for EV applications. A prototype of a five-phase 22-pole 5 kW motor drive has been designed for an experimental EV.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A high-performance inverter-fed drive system of an interior permanent magnet synchronous machine

A high-performance, fully operational four-quadrant control scheme for the interior permanent magnet (PM) synchronous machine is described. The machine operates smoothly with full performance in the constant-torque region as well as in the flux-weakening constant-power region in both directions of motion. The transition between the constant-torque region and the constant-power region is very smooth at all conditions of operation. Control in the constant-torque region is based on the vector stator flux, while constant-power region control is implemented through the feedforward vector rotator. The control system is digitally implemented using a distributed microcomputer system, and all of the essential feedback signals such as torque, flux, etc. are estimated with precision. A 70 hp drive system using a neodymium-iron-boron (NeFeB) PM machine and transistor pulse width modulation inverter was designed and extensively tested in the laboratory on a dynamometer, and performance was found to be excellent.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A microcomputer-based control and simulation of an advanced IPM synchronous machine drive system for electric vehicle propulsion

Describes a high-performance microcomputer-based control and digital simulation of an inverter-fed interior permanent magnet (IPM) synchronous machine that uses a neodymium-iron-boron magnet. The fully operational four-quadrant drive system includes a constant-torque region with zero speed operation and a high-speed field-weakening constant-power region. The control uses the vector or field-oriented technique in constant-torque region with the direct axis aligned to the stator flux, whereas the constant-power region control is based on torque angle orientation of the impressed square-wave voltage. All the key feedback signals for the control are estimated with precision. The drive system is basically designed with an outer torque control loop for electric vehicle application, but speed and position control loops can be added for other industrial applications. The distributed microcomputer-based control system is based on Intel-8096 microcontroller and Texas Instruments TMS32010 type digital signal processor.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Selection and Design of an Inverter-Driven Induction Motor for a Traction Drive System

The considerations and trade-offs involved in the selection and design of an inverter-driven induction motor for a traction drive system are described. The inverter is transistorized and operates in a pulsewidth modulation (PWM) mode in the constant torque region and in a six-step square wave mode in the constant power region. Drive system requirements establish the 50-hp peak motor rating and the motor voltage. The aspects of an induction motor designed to be driven from an inverter are presented. These include the number of poles and rotor bar shape of the motor. Expressions relating the motor performance to motor design parameters are derived. The aspects of the inverter power source are presented. These include the constant volt-ampere characteristics of the inverter and the relationship of motor inductance to the inverter design. A final motor design is reached, Contrary to previous expectations, the best design is a two-pole motor.

Steady-State Analysis of a Permanent Magnet Synchronous Motor Drive with Current Source Inverter

A steady-state analysis is presented of a permanent magnet (PM) synchronous motor drive with a current source inverter (CSI). The torque-speed profile required of the drive is a constant torque region from zero to base speed and a constant power region above base speed. The analysis assumes position feedback control. Optimum control strategies are obtained for the two regions of the torque-speed profile. Using these optimum strategies, performance curves of the drive are predicted and experimentally verified. The time harmonics in the motor are a function of the presence and configuration of the dampers in the motor. An expression is obtained for the equivalent inductance seen by the harmonics for different damper configurations. A Fourier series approach is used to predict the line-to-line voltage waveforms. Even though the presence of the dampers is not essential to the operation of the drive, their presence reduces the voltage spikes present in the line-to-line voltage.

Steady-State Analysis of a Permanent Magnet Synchronous Motor Drive with Voltage-Source Inverter

A steady-state analysis of a permanent magnet (PM) synchronous motor drive with a voltage-source inverter (VSI) is presented. The torque-speed profile required of the drive is a constant torque region from zero to base speed and a constant power region above base speed. Assuming position feedback control from a shaft-position sensor, optimum strategies are obtained for the two regions of the torque-speed profile. Using these optimum strategies, performance curves of the drive are predicted and experimentally verified. The harmonic distortion in the motor is strongly dependent on the presence and configuration of dampers in the motor. An expression is obtained for the equivalent inductance seen by the harmonics for different damper configurations. A Fourier series approach is used to predict the line current waveforms. Since dampers are not otherwise essential to the operation of this type of drive and since the line current without dampers is nearly sinusoidal, it is concluded that it is advantageous not to have dampers in the motor.

Reaming of an aluminum cast alloy, AC8B

The optimum condition to obtain the good surface finish of the reamed holes with accuracy was investigated in an aluminum cast alloy, AC8B. The results obtained are as follows:(1) The curve of torque vs cutting speed consisted of two parts, a constant torque region and a region, where torque increases acceleratedly with an increase of cutting speed.(2) Specific cutting resistance increased rapidly as the reaming depth increased. This is one of the characteristics in the cutting mechanism of "light cutting".(3) The accuracy of the reamed holes or the surface roughness linearly depended on the cutting speed. This result suggests that there is a certain relation between the cutting speed and the growth of built-up edges.(4) The optimum reaming condition was attained when the effective reaming depth and the cutting speed were, respectively, below 0.4mm and about 20m/min in the case of the cast alloy, AC8B.