561 research outputs found
A new sensorless method for switched reluctance motor drives
This paper describes a new method for indirect sensing of the rotor position in switched reluctance motors (SRMs) using pulse width modulation voltage control. The detection method uses the change of the derivative of the phase current to detect the position where a rotor pole and stator pole start to overlap, giving one position update per energy conversion. As no a priori knowledge of motor parameters is required (except for the numbers of stator and rotor poles), the method is applicable to most SRM topologies in a wide power and speed range and for several inverter topologies. The method allows modest closed-loop dynamic performance. To start up the motor, a feedforward stepping method is used which assures robust startup (even under load) from standstill to a predefined speed at which closed-loop sensorless operation can be applied. Experimental results demonstrate the robust functionality of the method with just one current sensor in the inverter, even with excitation overlap, and the sensorless operation improves with speed. The method is comparable to the back-EMF position estimation for brushless DC motors in principle, performance and cost. A detailed operation and implementation of this scheme is shown, together with steady-state and dynamic transient test results
Development of a drive system for a sequential space camera
An electronically commutated dc motor is reported for driving the camera claw and magazine, and a stepper motor is described for driving the shutter with the two motors synchronized electrically. Subsequent tests on the breadboard positively proved the concept, but further development beyond this study should be done. The breadboard testing also established that the electronically commutated motor can control speed over a wide dynamic range, and has a high torque capability for accelerating loads. This performance suggested the possibility of eliminating the clutch from the system while retaining all of the other mechanical features of the DAC, if the requirement for independent shutter speeds and frame rates can be removed. Therefore, as a final step in the study, the breadboard shutter and shutter drive were returned to the original DAC configuration, while retaining the brushless dc motor drive
Mathematical modelling of permanent-magnet brushless DC motor drives
Brushless dc motor drives have become increasingly
popular, following recent developments in rare-earth
permanent-magnet materials and the semiconductor devices used
to control the stator input power and to sense the rotor
position. They are now frequently used in applications such
as flight control systems and robot actuators, and for
drives which require high reliability, long life, little
maintenance and a high torque-to-weight ratio. In many motor
drives the presence of torque and speed ripples, especially
at low speed, is extremely undesirable. The mathematical
model developed in this thesis was used to investigate their
occurrence in a typical brushless dc drive system, with the
objective of establishing factors which effect their
magnitude and ways by which they may be reduced. The model
is based on the numerical solution of the differential
equations for the system, with those for the motor being
formulated in the phase reference frame. Tensor methods are
used to account for both the varying topology and the
discontinuous operation of the motor arising from changes in
the conduction pattern of the inverter supply switches.
The thesis describes the design, construction and testing
of an experimental voltage source PWM inverter, using MOSFET
switching devices, to drive a 1.3 kW 3-phase brushless dc
motor. A practical circuit is described which implements
current profiling to minimize torque ripple, and the optimum
phase current waveforms are established. The effect of
changes in the firing angle of the inverter switches on the torque ripple are also examined.
Throughout the thesis, theoretical predictions are
verified by comparison with experimental results
Critical Aspects of Electric Motor Drive Controllers and Mitigation of Torque Ripple - Review
Electric vehicles (EVs) are playing a vital role in sustainable transportation. It is estimated that by 2030, Battery EVs will become mainstream for passenger car transportation. Even though EVs are gaining interest in sustainable transportation, the future of EV power transmission is facing vital concerns and open research challenges. Considering the case of torque ripple mitigation and improved reliability control techniques in motors, many motor drive control algorithms fail to provide efficient control. To efficiently address this issue, control techniques such as Field Orientation Control (FOC), Direct Torque Control (DTC), Model Predictive Control (MPC), Sliding Mode Control (SMC), and Intelligent Control (IC) techniques are used in the motor drive control algorithms. This literature survey exclusively compares the various advanced control techniques for conventionally used EV motors such as Permanent Magnet Synchronous Motor (PMSM), Brushless Direct Current Motor (BLDC), Switched Reluctance Motor (SRM), and Induction Motors (IM). Furthermore, this paper discusses the EV-motors history, types of EVmotors, EV-motor drives powertrain mathematical modelling, and design procedure of EV-motors. The hardware results have also been compared with different control techniques for BLDC and SRM hub motors. Future direction towards the design of EV by critical selection of motors and their control techniques to minimize the torque ripple and other research opportunities to enhance the performance of EVs are also presented.publishedVersio
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
Development of an Efficient Propulsion System for a Battery Electric Shell Eco Marathon Prototype Vehicle
For the participation of the Aero@UBI team in Shell Eco-Marathon competition an in-wheel electric, ironless brushless permanent magnet motor was designed and build, this type of motors is characterized by very inductance and a very low resistance between phases which leads to current ripple, to solve this problem, and also, as Shell Eco-marathon competition requirements, a controller must be developed. In this case a controller with a 60-degree commutation was implemented and tested
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
A High Gain DC-DC Converter with Grey Wolf Optimizer Based MPPT Algorithm for PV Fed BLDC Motor Drive
Photovoltaic (PV) water pumping systems are becoming popular these days. In PV water pumping, the role of the converter is most important, especially in the renewable energy-based PV systems case. This study focuses on one such application. In this proposed work, direct current (DC) based intermediate DC-DC power converter, i.e., a modified LUO (M-LUO) converter is used to extricate the availability of power in the high range from the PV array. The M-LUO converter is controlled efficiently by utilizing the Grey Wolf Optimizer (GWO)-based maximum power point tracking algorithm, which aids the smooth starting of a brushless DC (BLDC) motor. The voltage source inverter’s (VSI) fundamental switching frequency is achieved in the BLDC motor by electronic commutation. Hence, the occurrence of VSI losses due to a high switching frequency is eliminated. The GWO optimized algorithm is compared with the perturb and observe (P&O) and fuzzy logic based maximum power point tracking (MPPT) algorithms. However, by sensing the position of the rotor and comparing the reference speed with the actual speed, the speed of the BLDC motor is controlled by the proportional-integral (PI) controller. The recent advancement in motor drives based on distributed sources generates more demand for highly efficient permanent magnet (PM) motor drives, and this was the beginning of interest in BLDC motors. Thus, in this paper, the design of a high-gain boost converter optimized by a GWO algorithm is proposed to drive the BLDC-based pumping motor. The proposed work is simulated in MATLAB-SIMULINK, and the experimental results are verified using the dsPIC30F2010 controller
- âŠ