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Fault tolerant drives for safety critical applicationsHaylock, James Alexander January 1998 (has links)
The correct operation of adjustable speed drives, which form part of a larger system, is often essential to the operation of the system as a whole. In certain applications the failure of such a drive could result in a threat to human safety and these applications are termed 'safety critical'. The chance of a component failure resulting in non-operation of the drive can be dramatically reduced by adopting a fault tolerant design. A fault tolerant drive must continue to operate throughout the occurrence of any single point failure without undue disturbance to the power output. Thereafter the drive must be capable of producing rated output indefinitely in the presence of the fault. The work presented in this thesis shows that fault tolerance can be achieved without severe penalties in terms of cost or power to mass ratio. The design of a novel permanent magnet drive is presented and a 'proof of concept' demonstrator has been built, based on a 20 kW, 13000 RPM aircraft fuel pump specffication. A novel current controller with near optimal transient performance is developed to enable precise shaping of the phase currents at high shaft speeds. The best operating regime for the machine is investigated to optimise the power to mass ratio of the drive. A list of the most likely electrical faults is considered. Some faults result in large fault currents and require rapid detection to prevent fault propagation. Several novel fault sensors are discussed. Fault detection and identification schemes are developed, including new schemes for rapid detection of turn to turn faults and power device short circuit faults. Post fault control schemes are described which enable the drive to continue to operate indefinitely in the presence of each fault. Finally, results show the initially healthy drive operating up to, through and beyond the introduction of each of the most serious faults.
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The behaviour and analysis of a three-phase AC-DC step-down unity power factor converterTooth, Daniel John January 1999 (has links)
No description available.
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Harmonic Currents Estimation and Compensation Method for Current Control System of IPMSM in Overmodulation RangeSmith, Lerdudomsak, Kadota, Mitsuhiro, Doki, Shinji, Okuma, Shigeru January 2007 (has links)
No description available.
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Analysis for Unstable Problem of PMSM Current Control System in Overmodulation RangeSmith, Lerdudomsak, Doki, Shinji, Okuma, Shigeru 10 1900 (has links)
No description available.
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A digital speed control for a chopper-fed DC motor by using the INTEL 8080 microcomputerLin, Andrew Kou-Chu January 2011 (has links)
Digitized by Kansas Correctional Industries
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Closed-loop Real-time Control of a Novel Linear Magnetostrictive ActuatorChen, Chien-Fan 2010 August 1900 (has links)
This thesis presents the design of various closed-loop real-time control of a novel
linear magnetostrictive actuator. The novel linear magnetostrictive actuator which uses
Terfenol-D as the magnetostrictive material was developed by Sadighi. It solves the
problem of power consumption in a conventional magnetostrictive actuator. However,
the control system of this magnetostrictive actuator cannot control the current in the coils,
which limits the performances of the real-time position control. In the closed-loop
real-time control system proposed in this thesis, the controller is designed depending on
the change of current.
The closed-loop real-time control design focused on the position control of the
active element in the novel linear magnetostrictive actuator. The closed-loop
position-control system of the linear magnetostrictive actuator was successfully designed
by implementing a closed-loop current-control system as an inner loop of the entire
control system. This design offers the flexibility to design various position controllers in
the closed-loop position-control system.
The closed-loop current-control design uses pulse-width modulation (PWM)
signal to change the current in the coils of the novel linear magnetostrictive actuator. By
changing the duty ratio of the PWM signal, the current in the coils can be changed from
zero to its maximum value. With a current controller using an integrator with a gain of
10, the current can be controlled with high response time and an error of /- 0.01 A.
The position-controller design was successfully conducted by using four different
approaches. First, a proportional-integral-derivative (PID) controller which was designed
by relay-auto tuning method with experiments exhibited a position error of ±1 μm with a
5 μm peak-to-peak position noise. Second, a PID controller which was designed by
root-locus can control the position with a position error of /- 3-4 μm with a 5 μm
peak-to-peak position noise. Third, a linear variable velocity controller exhibited a
position error of /-5 μm with a 5 mu m peak-to-peak position noise. Then, the sliding mode
control (SMC) exhibited a position error of /-5 μm with a 5 μm peak-to-peak position
noise.
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A Lithium-ion Battery ChargerXing, Hanwen, Liu, Xin January 2015 (has links)
Nowadays personal small electronic devices like cellphones are more and more popular, but the various batteries in need of charging become a problem. This thesis aims to explain a Lithium-ion charger which can control the current and voltage so that it can charge most kinds of popular batteries. More specifically, Li-ion battery charging is presented. The charging circuit design, simulation and the measurements will also be included.
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Equivalent Linear Model Based Torque Control and Performance Improvement For Switched Reluctance Motor (SRM) DrivesFang, Gaoliang January 2021 (has links)
Switched reluctance machines (SRMs) are gaining increasing interest in industrial applications due to their low manufacturing cost, simple and robust structure, excellent fault-tolerant capability, and reliable operation in high-temperature operating environments. However, the inherent pulsative torque and radial force lead to the well-known torque ripples and acoustic noise issues. Although there are numerous advanced methods to address the above two issues, the high nonlinearity inevitably brings difficulties in controlling the SRMs.
Since the linear SRM voltage and toque equations are simple, it would be beneficial to explore the control algorithm by using such simple linear model. The application of the linear torque model is firstly explored. To utilize such simple model, the connections between the linear toque model and the nonlinear torque model are built through the mapping. The features of these mapping curves are studied in detail. Applying the linear torque equation to generate the reference currents in the optimization-based torque sharing function method shows a significant reduction of the time consumption in solving the bi-optimization problem.
Later, the complete equivalent linear SRM model is constructed by introducing the linear voltage equation and corresponding mapping. Since the linear model is easy to predict the behaviour of SRMs, it is beneficial to apply such model in the model predictive torque control (MPTC) methods. The application of the equivalent linear model in the finite control set (FCS) MPTC method shows a low computational burden and occupies less storage space. Besides, the improved switching table in the proposed FCS MPTC method also enhances the torque control performance in high-speed operation conditions. To further reduce the torque ripples, the continuous control set (CCS) MPTC method is developed based on the constructed equivalent linear SRM model. The impossibility in analytically solving the optimization problem in the CCS MPTC method if using the original nonlinear SRM model is innovatively addressed by using the equivalent linear SRM model and properly modifying the cost function. Extensive simulation and experimental results prove the low-ripple feature of the proposed CCS MPTC method in a wide speed range.
The high nonlinearity also makes the current control of SRM drives difficult. An intersection-method-based current controller is presented to ensure good current tracking performance for SRMs. The employed adaptive flux-linkage observer makes this current controller show robust performance when there is a deviation on the employed flux-linkage characteristics.
Finally, the key but unmeasurable radial force information for the advanced acoustic reduction method is reconstructed based on the measured flux-linkage curves and some core relationship. This core relationship, which is between the square root of the radial force and the flux-linkage, is explored in detail. Simulation results reveal that the proposed method shows good radial force estimation accuracy when there is even 50% airgap length variation. / Thesis / Doctor of Philosophy (PhD)
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A no load simulation model of a DC drive systemDudley, Guy Mandel January 1983 (has links)
This research investigates the modeling and simulation, using the state transition approach to nonlinear system simulation, of a DC drive system. The drive system that was modeled is a closed loop system composed of a velocity loop with an inner current loop. The power stage is composed of a pulse generator module and a scr bridge, while the motor is a permanent magnet DC motor.
A detailed development of each module model is included to reveal the open loop characteristics of the system. A total system state model was developed from each of the modules and closed loop simulations were run. The results show that the system may be modeled and simulated using this technique. However, the exactness of the simulation is heavily dependent on the DC motor parameters selected for the model. / Master of Science
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Nonlinear Deadbeat Current Control of a Switched Reluctance MotorRudolph, Benjamin 07 January 2010 (has links)
High performance current control is critical to the success of the switched reluctance motor (SRM). Yet high motor phase nonlinearities in the SRM place extra burden on the current controller, rendering it the weakest link in SRM control. In contrast to linear motor control techniques that respond to current error, the deadbeat controller calculates the control voltage by the current command, phase current, rotor position and applied phase voltage. The deadbeat controller has demonstrated superior response in three-phase inverter current control, PM motor current control, and other relatively linear control applications. This study will investigate the viability and performance of a deadbeat controller for the highly nonlinear SRM.
The need for an accurate deadbeat control model first motivates the investigation of experimental inductance measurement techniques. A deadbeat control law is then proposed through multiple revisions to demonstrate the benefit of the numerical method chosen to derive the controller and a current predictor that accounts for processor latency and PWM delay. The practical problems of loop delay, feedback noise, feedback filtering, and deadbeat controller parameter sensitivity are investigated by linear analysis, simulation, experimental implementation and nonlinear model analysis. Simulation and implementation verify deadbeat performance and various measures of transient performance are presented. To address the problem of SRM model error the study ends with a brief discussion of adaptive deadbeat control modifications for possible future research. / Master of Science
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