Observer-based tuning of two-inertia servo-drive systems with integrated SAW torque transducers

This paper proposes controller design and tuning methodologies that facilitate the rejection of periodic load-side disturbances applied to a torsional mechanical system while simultaneously compensating for the observer’s inherent phase delay. This facilitates the use of lower-bandwidth practically realizable disturbance observers. The merits of implementing full- and reduced-order observers are investigated, with the latter being implemented with a new low-cost servo-machine-integrated highband width torque-sensing device based on surface acoustic wave (SAW) technology. Specifically, the authors’ previous work based on proportional–integral–derivative (PID) and resonance ratio control (RRC) controllers (IEEE Trans. Ind. Electron., vol. 53, no. 4, pp. 1226–1237, Aug. 2006) is augmented with observer disturbance feedback. It is shown that higher-bandwidth disturbance observers are required to maximize disturbance attenuation over the low-frequency band (as well as the desired rejection frequency), thereby attenuating a wide range of possible frequencies. In such cases, therefore, it is shown that the RRC controller is the preferred solution since it can employ significantly higher observer bandwidth, when compared to PID counterparts, by virtue of reduced noise sensitivity. Furthermore, it is demonstrated that the prototype servo-machine-integrated 20-N · mSAWtorque transducer is not unduly affected by machine-generated electromagnetic noise and exhibits similar dynamic behavior as a conventional instrument inline torque transducer

High performance position control for permanent magnet synchronous drives

In the design and test of electric drive control systems, computer simulations provide a useful way to verify the correctness and efficiency of various schemes and control algorithms before the final system is actually constructed, therefore, development time and associated costs are reduced. Nevertheless, the transition from the simulation stage to the actual implementation has to be as straightforward as possible. This document presents the design and implementation of a position control system for permanent magnet synchronous drives, including a review and comparison of various related works about non-linear control systems applied to this type of machine. The overall electric drive control system is simulated and tested in Proteus VSM software which is able to simulate the interaction between the firmware running on a microcontroller and analogue circuits connected to it. The dsPIC33FJ32MC204 is used as the target processor to implement the control algorithms. The electric drive model is developed using elements existing in the Proteus VSM library. As in any high performance electric drive system, field oriented control is applied to achieve accurate torque control. The complete control system is distributed in three control loops, namely torque, speed and position. A standard PID control system, and a hybrid control system based on fuzzy logic are implemented and tested. The natural variation of motor parameters, such as winding resistance and magnetic flux are also simulated. Comparisons between the two control schemes are carried out for speed and position using different error measurements, such as, integral square error, integral absolute error and root mean squared error. Comparison results show a superior performance of the hybrid fuzzy-logic-based controller when coping with parameter variations, and by reducing torque ripple, but the results are reversed when periodical torque disturbances are present. Finally, the speed controllers are implemented and evaluated physically in a testbed based on a brushless DC motor, with the control algorithms implemented on a dsPIC30F2010. The comparisons carried out for the speed controllers are consistent for both simulation and physical implementation

Harjattoman tasavirtamoottorin arviointi opto-mekaanisessa paikkasäätösovelluksessa

This thesis evaluates the applicability of a micro-sized brushless direct current (DC) mo- tor in an opto-mechanical positioning application. Brushless DC motors are electronically commutated motors that use permanent magnets to produce the airgap magnetic field. The motor is powered through an inverter or switching power supply which produces an AC electric current to drive each phase of the motor. Optimal current waveforms are determined by the motor controller based on the desired torque, speed or position requirements. The benefits of a brushless motor over conventional brushed DC motors are a high power to weight ratio, low noise and a long operating life. The purpose of this thesis is to find out the performance potential of such motors and determine methods to achieve it. Firstly, a motor model and an exact motor classification is presented. A literature review is made to discuss state of the art control methods and hardware configurations for dynamic position control. Based on the literature review, a control scheme with field-oriented control based torque control and cascaded PI controlled speed and position loops was selected for further evaluation. Experimental positioning tests were executed for two motors with different power transmission setups. Tests were performed with both, a hardware and software implemented, motor controllers. Results show promising performance. It was shown that the required acceleration is feasible with both, geared and direct drive, transmissions. Field-oriented control was shown as a well performing method to control torque but special caution was needed to implement a reliable position sensing solution in a small size as the control algorithm is intolerant for inaccurate and noisy position data. The conventional PI based position controller was effective in cases with no feedback related harmonics or motor related torque ripple but was not capable in handling ripple caused by a non-ideal system. Quality variances were seen between motors which were originated from mechanical defects and non-idealities in the stator structure. Further research is needed to achieve a better settling performance through filtering undesired feedback harmonics, better tuning and thus minimizing undesired vibrations.Tämän diplomityön tarkoituksena on arvioida pienikokoisen harjattoman tasavirtamoottorin soveltuvuutta opto-mekaaniseen paikkasäätösovellukseen. Harjattomat tasavirtamoottorit ovat elektronisesti ohjattuja moottoreita, joissa ilmavälin magneettivuo luodaan kestomagneeteilla. Moottorille syötetään virtaa taajuusmuuttajalta, joka muodostaa halutunlaisen vaihtovirran jokaiselle moottorin vaiheelle. Syötettävää virtaa ohjataan moottorinohjaimelta määritettyjen vääntö-, nopeus- ja paikkavaatimusten perusteella. Harjattoman DC-moottorin edut verrattuna perinteiseen harjalliseen DC-moottoriin ovat hyvä teho-painosuhde, hiljainen käyntiääni ja pitkä käyttöikä. Diplomityön tavoitteena on kartoittaa kyseisen moottorityypin suorituskyky paikkasäädössä ja tutkia keinoja saavuttaa haluttu taso. Alan tutkimuksessa ja kirjallisuudessa tunnettuja suorituskykyisiä säätömenetelmiä ja laite- sekä komponenttikokoonpanoja on koostettu kirjallisuuskatsauksessa. Tämän perusteella kokeellisiin testeihin valittiin säätöarkkitehtuuri vektorisäätöön perustuvalla virransäädöllä sekä PI-pohjaisilla nopeus- ja paikkasäätimillä. Kokeellisilla paikoitustesteillä arvioitiin kahden moottorin suorituskykyä erilaisilla voimansiirtovaihtoehdoilla. Testit suoritettiin sekä ohjelmistopohjaisella että sovelluskohtaiseen mikropiiriin toteutetulla laitepohjaisella säätimellä. Tulokset osoittavat että vaaditun kiihtyvyyden saavuttaminen on mahdollista sekä vaihteellisella että suoravetoisella voimansiirrolla. Vektorisäätö osoittautui suorituskykyiseksi virransäätömenetelmäksi, mutta moottorin asentomittauksen luotettava toteutus vaati erityishuomiota, sillä vektorisäätöalgoritmi on herkkä paikkadatan tarkkuudelle. PI-säätimillä toteutettu paikkasäätö osoittautui toimivaksi, mutta herkäksi moottorin epäideaalisuuksille sekä häiriöille takaisinkytkennässä. Moottoreiden välillä havaittiin laatueroja mekaanisissa toleransseissa ja staattorin rakenteessa. Lopullisen asettumisajan saavuttaminen vaatii lisätutkimusta. Erityishuomiota on kiinnitettävä harmonisten komponenttien suodattamiseen sekä systeemin säätöön, jotta ei-toivotut värinät saadaan minimoitua

Vector Controlled Drives Of Permanent Magnet Synchronous Motor Using Pi Speed Controller For Long Cable Application

This paper present a vector controlled drives of Permanent Magnet Synchronous Motor (PMSM) by using Proportional-Integral (PI) Speed controller for long cable application. As known, long cable caused an over voltage problem at motor terminal and could be double from the pulse output voltage at inverter terminal. This caused instability of the speed performances. PI speed controller is implemented to drive a PMSM with different cables length to investigated the speed performances, load disturbances and parameter variations of the system. Hysteresis current controller is used for inner loop current control and PI controller for outer loop speed control. Simulation results are provided to show performances on different cable length driving a PMSM

Analytical investigation of sideband electromagnetic vibration in integral-slot PMSM drive with SVPWM technique

This paper provides a comprehensive investigation into the electromagnetic vibration associated with the sideband harmonic components introduced by space vector pulse width modulation applied in integral-slot permanent magnet synchronous machine drives. The critical permanent magnet, armature reaction, and sideband magnetic field components, which are the primary causes for sideband electromagnetic vibration in integral-slot permanent magnet synchronous machines, are identified. The analytical derivations of the magnetic field components are carried out, and amplitudes and frequencies of the resultant sideband radial electromagnetic force components are obtained. Furthermore, the proposed models of the sideband radial electromagnetic force components are incorporated into the vibration model to analytically evaluate the corresponding sideband electromagnetic vibrations of the machine. Experimental tests on an integral-slot permanent magnet synchronous machine drive are comprehensively performed to confirm the validity and accuracy of the analytical models. Not only can the validated analytical models offer insightful details in understanding the impacts of the key factors, such as operation conditions, machine geometry, electromagnetic and power converter parameters, on the sideband electromagnetic vibration, but also can be readily extended to assess and reduce noise in integral-slot permanent magnet synchronous machine drives

Torque Enhancement of Dual Three-Phase PMSM by Harmonic Injection

The torque enhancement of dual three-phase permanent magnet synchronous machine (DT-PMSM) drive system by full exploitation of flux-linkage and current harmonics are comparatively studied in this paper. The torque capability of DT-PMSM is previously evaluated with strategies of harmonics utilization, i.e. Strategy-1 of 3rd harmonic utilization and Strategy-2 of 5th and 7th harmonic utilization, which can extend the torque capability by 18.2% and 9.0% respectively. However, the full exploitation of harmonics including 3rd, 5th and 7th harmonics in the dual three-phase system are not addressed. In this paper, the Strategy-3 of 3rd, 5th and 7th harmonic utilization is also included. Its corresponding harmonic current control is proposed and the average torque and harmonic torque are analyzed in detail. Based on a test rig with existing prototype DT-PMSM, the torque with Strategy-3 is increased up to 26.5%, which is superior to the previous strategies

A novel adaptive PD-type iterative learning control of the PMSM servo system with the friction uncertainty in low speeds

High precision demands in a large number of emerging robotic applications strengthened the role of the modern control laws in the position control of the Permanent Magnet Synchronous Motor (PMSM) servo system. This paper proposes a learning-based adaptive control approach to improve the PMSM position tracking in the presence of the friction uncertainty. In contrast to most of the reported works considering the servos operating at high speeds, this paper focuses on low speeds in which the friction stemmed deteriorations become more obvious. In this paper firstly, a servo model involving the Stribeck friction dynamics is formulated, and the unknown friction parameters are identified by a genetic algorithm from the offline data. Then, a feedforward controller is designed to inject the friction information into the loop and eliminate it before causing performance degradations. Since the friction is a kind of disturbance and leads to uncertainties having time-varying characters, an Adaptive Proportional Derivative (APD) type Iterative Learning Controller (ILC) named as the APD-ILC is designed to mitigate the friction effects. Finally, the proposed control approach is simulated in MATLAB/Simulink environment and it is compared with the conventional Proportional Integral Derivative (PID) controller, Proportional ILC (P-ILC), and Proportional Derivative ILC (PD-ILC) algorithms. The results confirm that the proposed APD-ILC significantly lessens the effects of the friction and thus noticeably improves the control performance in the low speeds of the PMSM

Torque capability enhancement of dual three-phase PMSM drive with fifth and seventh current harmonics injection

© 2017 IEEE. A method for enhancing torque capability of a dual three-phase permanent magnet synchronous machine (PMSM) based on conventional dual three-phase drive system by injecting the fifth and seventh current harmonics without any hardware re-configuration is proposed in this paper. Compared with the third current harmonic injection, which is commonly used to enhance the torque capability of dual three-phase machine, the two isolated neutral points of each set of single three-phase windings do not need to be reconnected to the middle point of dc-link capacitors or an additional power switching bridge to provide flowing path for zero-sequence current. Further, no additional current sensors are required to obtain the feedback of zero-sequence current to regulate it effectively. For a prototype dual three-phase PMSM, the average torque increases approximately by 9% at the cost of 0.56% increase in the 12th harmonic torque ripple. The effectiveness of the torque capability enhancement is confirmed by experiments