Direct torque control of brushless DC drives with reduced torque ripple

The application of direct torque control (DTC) to brushless ac drives has been investigated extensively. This paper describes its application to brushless dc drives, and highlights the essential differences in its implementation, as regards torque estimation and the representation of the inverter voltage space vectors. Simulated and experimental results are presented, and it is shown that, compared with conventional current control, DTC results in reduced torque ripple and a faster dynamic response

Development Of Sensorless Speed Control Based On Back-Emf Zero Crossing For Three-Phase Brushless Dc Motor

This research focuses on design development and hardware implementation for a sensorless operation to drive a 16-pole, three-phase Brushless DC Motor. The proposed operation adopted a dsPIC30F3010 digital signal controller developed by Microchip Technology Inc. The digital signal controller has the advantage of low-cost implementation, small and compact size factors and minimum hardware requirements. The development board used in this research is PICDEM MC LV development board produced by Microchip Technology Inc. The development board provides a cost-effective method in developing and evaluating a sensorless motor application. By using this board together with the digital signal controller, a sensorless motor application using Back-EMF zero-crossing technique is implemented and used to derive the commutation sequence. The no-load experimental results shows that at 50% duty cycle, the motor speed is about 2393 rpm with terminal voltage 10.08V, and at 80% duty cycle, the maximum motor speed is about 4110 rpm with terminal voltage 11.98V. The speed controller produces motor speed that is proportional to terminal voltage supply. Therefore, it confirms the theoretical principle of BLDC motor operation

Design of a Printed Circuit Board for a Sensorless Three-Phase Brushless DC Motor Control System

The use of brushless motors has increased in recent years due to superior performance characteristics compared with alternatives. The operation of a brushless motor is dependent upon a separate controller which is often in the form of a printed circuit board. As such, the size and performance capability of the controller can restrict the performance of the overall motor control system so advancements of these controllers further the potential use of BLDC motors. This project outlines the design of a PCB based, sensorless motor controller for operation of a three-phase BLDC motor powered by a 24 V, high current external supply. Components used were selected to withstand an ambient temperature environment of 125 degrees C. The design for this PCB based motor control system was completed but fabrication and testing of the system was prevented by COVID-19 related restrictions that prohibited the use of necessary facilities and equipment. The detailed design including component selection, board layout, and software development is included in addition to a plan for fabrication and fundamental functional testing. Although no results are available for analysis to bring about any conclusions, a variety of design strategies and corresponding learnings hold the potential to be a source of valuable reference to the further study and development of future designs

Position estimation and performance prediction for permanent-magnet motor drives

PhD ThesisThis thesis presents a theoretical and experimental development of a novel position estimator, a simulation model, and an analytical solution for brushless PM motor drive. The operation of the drive, the position estimation model of the test motor, development of hardware, and basic operation of inverter are discussed. Starting with the well-known continuous-time model of brushless PM motor, a sampled-data model is developed that is suitable for th6, application of real-time position estimator. An analytical methodo f calculating the steady-stateb ehaviouro f the brushlessP M motor for 1200in verter operation is presentedT. he analysisa ssumesth at the machinea ir gap is free of saliency effects, and has sinusoidal back EMF. The analytical solution is derived for 60" electrical of the whole period. By experimental results, it is shown that the method of analysis is adequate to predict Ihe motor's performance for typical operating points including phase advance and phase delay operation. C) I A computer simulation model for prediction of the performance of brushless PM moto rs is presented. The model is formulated entirely in the natural abc frame of reference, which allows direct comparison of the simulation and corresponding experimental results. The equations and diagrams are put into a convenient form for the simulation and future developments and library modules. The simulation model and corresponding experimental data of the brushless PM motor drive is given. The thesis describes a modem solution to real-time rotor position estimation, which has been subject to intense research activity for the last 15 years. The implemented new algorithm for shaft position sensorless operation of PM motors is based on the flux linkage and line current estimation. The position estimation algorithm has also been verified by both off-line and on-line experiments (accomplished by a DSP, TMS320C30), and a wide range of steady-statea nd transient results have been 0gi0v en including starting from rest. The position estimation method effectively moves the position measurement point in the drive from the mechanical side to the motor's terminals. As well as eliminating the mechanical shaft position sensor, the investigated method can be used for high performance torque control of brushless PM motors. The thesis demonstrates that, in contrast to many other "sensorless" schemes, the new position estimation method is able to work effectively over the full operating range of the drive, and is applicable to a wide range of motor/converter types. Since the hardware is straightforward, only the new position estimation algorithm differentiates a system. Therefore, if a DSP control system is already implemented in the drive, the position estimator can be implemented at low cost.Istanbul Technical University and Higher Education Counci

Rotor Position Identification for Brushless DC motor

Permanent magnet BLDC motors are characterized by a central magnetic core, called the rotor, and fixed electric coils (usually six) equally spaced in a ring around the core, called the stator. Motor movement is controlled by alternately energizing and de-energizing the stator coils to create a rotating magnetic field that propels the rotor. In order for this process to work correctly, BLDC motors required a technology called electronic commutation, in which the coil currents must be very carefully synchronized to rotor position to ensure that the rotating field is correctly aligned with the permanent magnetic field in the rotor. Usually rotor position is measured by external sensors such as Hall-effect sensors and optical encoders and these external sensors increase the system cost and reduces reliability. In order to control the price and make it more reliable this thesis propose to infer the rotor position from voltage and current measurement of motor. The most common approaches to sensorless control are based on the measurement of the electromotive force (back-EMF), that is induced by the rotor motion. As the back-EMF is nearly zero at very low speed and at stationary position, and can not be measured. Therefore a separate algorithm is required for start-up and control at low speed. The other method of sensorless control involves the inference of rotor position from the variation in inductance caused by rotor position. This thesis presents a prototype system for sensorless control of BLDC motors over the entire speed range of the motor, including stall (zero speed) conditions using the voltage and current signals from the motor

STUDY OF PHASE ADVANCE ANGLE CONTROL METHOD FOR BRUSHLESS DC (BLDC) MOTOR

The brushless DC (BLDC) motor is recognized by the linear speed to voltage and torque to current. It has high fast dynamic response and high power density with high proportion of torque in sprite of small size drive. However, it is difficult to conventional BLDC motor to drive at high speed operating mode (limited top speed). It is because of the torque and speed response characteristic of the motor at high speed operating mode are deteriorated by the motor inductance components in stator winding. Phase advance angle method is one method used to control the phase current and improve torque and speed response at high speed operating mode of BLDC motor. This project concentrates on the operation of BLDC motor under high-speed motoring mode. Extended simulation results prove the validity of phase advance angle control method, considering lossless motor operation and the same parameters of an actual BLDC motor. In this project also, the results of laboratory testing are demonstrated to prove the compatibility of the purposed phase advance motor drive on actual BLDC motor. Both simulation and experimentation results confirm that phase advance angle control method is capable to extend the speed beyond the designed motor speed

Efficiency comparison of trapezoidal and sinusoidal method for brushless DC motor drive

This paper compares overall efficiency of trapezoidal BLDC motor which is excited by trapezoidal drive and sinusoidal drive. The different characteristics and performance of trapezoidal brushless DC (BLDC) motor is formed by driving methods. Sinusoidal drive that excites trapezoidal BLDC motor generates greater maximum torque than trapezoidal drive. However, with regard to high frequency loss caused by a pulse width modulation (PWM) carrier and switching loss, the trapezoidal drive has potential to achieve higher efficiency than the sinusoidal drive. Thus, these two drive methods excite trapezoidal BLDC motor are compared to study the performance of efficiencies. The motors drives are simulated by using MATLAB and their efficiencies are measured. The results show that the trapezoidal BLDC motor with trapezoidal drive has higher efficiency compared to trapezoidal BLDC motor with sinusoidal drive

Right Harmonic Spectrum for the back-electromotive force of a n-phase synchronous motor

This paper deals with a vector control of n-phase permanent magnet synchronous machine. To use control algorithms already developed for sine-wave 3-phase machines, the spectrum of back electromotive force (EMF) must contain only odd 2k+1 harmonics which verify the following inequality, 1≤ 2k +1< n . In an experimental vector control of a 5-phase drive, two usual algorithms of sine-wave 3-phase machine are thus used to supply a machine with trapezoidal waveform back EMF. In this case, the first and third harmonics are used to produce torque: the other harmonics, and particularly the 7th one, induce effects as torque ripples and parasitic currents

Electronic Control of Torque Ripple in Brushless Motors

Merged with duplicate record 10026.1/727 on 27.02.2017 by CS (TIS)Brushless motors are increasingly popular because of their high power density, torque to inertia ratio and high efficiency. However an operational characteristic is the occurrence of torque ripple at low speeds. For demanding direct drive applications like machine tools, robot arms or aerospace applications it is necessary to reduce the level of torque ripple. This thesis presents an in depth investigation into the production and nature of torque ripple in brushless machines. Different torque ripple reduction strategies are evaluated and one reduction strategy using Park's transform as a tool is identified as the promising strategy. The unified machine theory is checked to clarify the theory behind Park's transform; in particular assumptions made and general validity of the theory. This torque ripple reduction strategy based on Park's transform is extended to include the effect of armature reaction. A novel adaptive torque ripple reduction algorithm is designed. The ineffectiveness of the conventional approach is demonstrated. Further a novel torque ripple reduction strategy using direct measurements of the torque ripple is suggested, reducing implementation time and allowing higher accuracies for torque ripple reduction. Extensive measurements from the experimental system show the validity of the novel torque ripple reduction strategies. The experimental results allow derivation of a formula for all load situations. This formula makes it possible to further increase the reduction accuracy and enables improved real time implementation of the torque ripple reduction algorithm. The work presented here makes a substantial contribution towards understanding the nature of torque ripple in brushless motors and solving the associated problems. The novel reduction strategies form the basis for the development of intelligent dynamometers for motor test beds. Further the torque ripple reduction method presented here can be used to overcome manufacturing imperfections in brushless machines thus removing the cost for precise manufacturing tools. Future designs of controllers can "build" their own correction formula during set-up runs, providing a motor specific torque ripple correction.Automotive Motion Technology Lt