Добірка наукової літератури з теми "Split-phase induction machine"

In order to reduce the costs of implementing the radial position control system of a three-phase bearingless machine with split winding, this article proposes a driving method that uses only two phases of the system instead of the three-phase traditional one. It reduces from six to four the number of inverter legs, drivers, sensors, and current controllers necessary to drive and control the system. To justify the proposal, this new power and control configuration was applied to a 250 W machine controlled by a digital signal processor (DSP). The results obtained demonstrated that it is possible to carry out the radial position control through two phases, without loss of performance in relation to the conventional three-phase drive and control system.

Pole-phase changing induction machines (IMs) offer the capability to extend the torque-speed envelope compared to their fixed pole-phase counterparts. Dynamic pole-changing can achieve higher torque levels at lower speeds, utilizing higher pole numbers, and extended flux-weakening range with lower pole-number operations. This paper investigates the design impact on the optimum pole-phase changing behavior and respective split of the operating region to different pole-phase operations. Additionally, the improvement in terms of the overall torque per ampere capability and efficiency is illustrated. For the purposes of the analysis, two different IMs with wound independently-controlled stator coils (WICSC) and different original pole numbers are evaluated in an effort to quantify the extent of the benefits of pole-phase changing. These geometries correspond to machines that were originally designed with 2- and 6 magnetic poles, respectively. It is shown that, in the case of the original 2-pole WICSC machine, shifting to a higher pole number is notably beneficial in terms of efficiency in a significant part of the operating region, whereas in the original 6-pole, both higher and lower pole numbers significantly enhance the overall torque capability and efficiency. The results highlight the notable benefits of pole-phase changing IMs and offer deep insight towards the derivation of standard design guidelines for these machines.

This paper presents a case study on capacitor failure analysis in Permanent-Split Capacitor-Run SinglePhase Induction Motor (PSCRSPIM) in low slip region. It emphasizes the motor performance in low slip region and detailed analysis carried out for Capacitor voltage and current variation with respect to slip. Motor Equivalent circuit parameters are extracted from dc test, no-load test and locked-rotor test. MATLAB simulations are carried out. Theoretical and experimental results are plotted. The premature failure of capacitor faced by PSCRSPIM users is answered at the end of the Paper. Contrary to the general concept that overloaded machine will fail; the paper is addressing the failure of lightly loaded machines.

This thesis presents a re-designed conventional three phase 5-hp squirrel cage, 4-pole, 48 slots induction motor to a six-phase induction motor (SPIM). It also presents the in-depth of a single layer winding of a three-phase motor that was re-design to the six-phase split winding layout which was practically explained to the understanding of both the engineers and the technicians who normally find it difficult with windings of electrical machines. The optimized re-designed SPIM is presented in the MATLAB/Simulink environment to perform a comparative assessment of the different phase loss scenarios of the six-phase configuration with respect to the six-phase healthy case and its conventional three-phase induction motor. The result shows a comparative benefit of the six-phase induction motor over the three-phase induction motor; in such that in the near future because of its effective way to provide a higher reliability and sustainability under the loss of phase/phases condition it will be practically applied in the power driven devices/machines like in the area of Electric Vehicles, etc.

In this thesis, the nature of asynchronous and synchronous torques in a split-phase induction machine is investigated and quantified. The equivalent circuit for this type of machine is derived using the rotating field theory. It is extended to include harmonic effects. Using this model, winding harmonics and permeance harmonics may be calculated independently of each other so that the model can be used to analyse asynchronous torques from winding harmonics as well as synchronous torques from permeance harmonics. These are calculated separately. The asynchronous torques appear as perturbations in the steady-state torque-speed curve while the synchronous torques only appear at specific speeds. The synchronous torques are superimposed onto the torque-speed curves to model both effects together. The model predictions are compared against test results using purpose-built experimental machines together with production machines. These have varying rotor bar number and skew. Different methods are used to assess the synchronous torques. It is found that measuring synchronous locking torque is not a straightforward matter; however, reasonable agreement is found between calculation and measurement. The work highlights the need for the correct choice of stator and rotor slot numbers together with the effect skew has on reducing the synchronous and asynchronous locking torques.

Induction machine (IM) is the workhorse of several industries due to its low cost and minimal maintenance. Power electronic converters play a major role in driving IMs which give better flexibility in these applications. With the advancement of production levels and effi ciency, the power-level demands of the industries are going up day by day. To meet this increased power-demand, the required ratings of the power converter components are also increased which sometimes can't be realized with the existing technologies. Due to this limitation, induction machines with more than three phases are becoming popular where the power handled by each phase is reduced compared to three-phase machine for the same power rating of IM. These machines are called multi-phase machine and six-phase machine is one of the most popular multi-phase machines. Six-phase machine is of two types: Symmetrical and Asymmetrical. In symmetrical six-phase machine, all the six stator windings are spatially displaced by 60 electrical. Asymmetrical six-phase machine, also known as split-phase induction machine (SPIM), has two sets of balanced three-phase windings which are displaced by 30 degree electrical. The later confi guration has become popular due to its less susceptibility to the time-harmonic components present in the excitation waveform. This thesis is aimed at studying the modulation strategies of SPIM driven by the power-electronic converter. There are two types of power-converters to drive SPIM: DC-AC (Inverter) and AC-AC (matrix converter). The thesis provides detailed discussions on winding structure, nature of excitation, dynamic modeling and steady-state equivalent circuit of SPIM which are required to investigate the modulation strategies of power-converter fed SPIM drive. The dynamic model of SPIM reveals that the fundamental component and a selective group of odd harmonics can contribute to the air-gap flux and hence participate in electromagnetic energy transfer and torque production. The equivalent circuit seen by the fundamental component and the above group of harmonics is similar to the equivalent circuit of three-phase IM. There is another group of odd harmonics which doesn't contribute to the air-gap flux and the equivalent circuit seen by this group consists of stator resistance and leakage inductance. So the excitation of SPIM with these harmonics will cause a large amount of harmonic currents due to low impedance of the equivalent circuit. These harmonic currents don't contribute to the air-gap flux or torque ripple but cause copper losses. So the objective of SPIM modulation is to excite the machine with fundamental component and zero or minimal injection of harmonics belonging to the first or second group. Vector Space Decomposition (VSD) technique, which exists in the literature, modulates the SPIM without injecting any harmonics in the line-neutral voltage. In this thesis, the modulation index of inverter fed SPIM drive has been de fined as the ratio of peak fundamental line-neutral voltage and DC-bus voltage. This thesis provides the derivation of the maximum modulation index achieved by VSD technique. This work tries to unify the understandings behind the existing modulation techniques by proposing a new way of modeling of six-phase inverter. The existing Conventional Space Vector PWM (CSVPWM) technique modulates the SPIM by keeping air-gap flux sinusoidal and it attains the modulation index higher than the maximum modulation index achieved by VSD technique by injecting signifi cant amount of second group of harmonics. Although this group of harmonics doesn't create any torque ripple in the machine, higher injection results into reduction in the efficiency of the SPIM drive modulated by CSVPWM technique. To overcome this, two novel modulation techniques have been proposed in this thesis for the modulation index higher than the maximum modulation index obtained by VSD technique and these two techniques have much-reduced injections of the second group of harmonics compared to CSVPWM. One of these two techniques is able to attain the complete range of modulation index as can be achieved by the CSVPWM and this technique solves a constraint optimization problem in order to minimize the second group of harmonics injection. Another technique is easy to implement but it doesn't attain the whole range of modulation index as achieved by CSVPWM. Within the sub-range, the performance of the second technique is close to the performance of the first technique. The thesis also explores the modulation of matrix converter (MC) fed SPIM drive. Although MC is a promising candidate for drive applications due to high power density and extended lifetime in absence of DC-link electrolytic capacitor, modulation technique of MC fed SPIM drive doesn't exist in the literature. A modulation technique of MC fed SPIM drive has been proposed in this work and this technique keeps the air-gap flux sinusoidal without injecting any harmonics in the line neutral voltage. The proposed modulation techniques have been veri fied by the experiments performed on laboratory prototype hardware built and tested in the lab. The design details of these hardware prototypes are included in this thesis.

This chapter presents a simple method to efficiently predict the rotor speed for a sensorless vector control technique applied to induction motors (IMs). The motor is supplied by a Simplified Split-Source Inverter (S3I), which provides dc-boosting and ac-inversion processes during input voltage sag. It also has a wider modulation range and a lower harmonic content than conventional boosting inverters. With this contribution, it is possible to efficiently estimate the rotor position directly without needing a PI controller with fluctuated supply voltage. The proposed strategy can be divided into three parts. The first uses a dual-loop controller to obtain the reference DC-boosted voltage of the SSI and regulate the input current. The second is the suggested observer for speed detection, which is derived from the principles of phase axis relations of the adopted machine currents and the indirect rotor flux orientation control (IRFOC) approach. With a newly developed space vector modulation, the third part will generate the switching pulses of the inverter switches. A complete analysis has been conducted to ensure the observability of the proposed technique. A series of PLECS simulations were conducted to verify the concept. The obtained results validate the proposed strategy with the S3I topology.