Capacitor Motor Research Articles

Critical Slip and Characteristics of Induction Motor for Borehole Investigating Devices

If the borehole medium temperature did not exceed +2000C, it is successfully used single-phase asynchronous capacitor motor with solid ferromagnetic rotor for the borehole investigating device drive. For the boreholes of which medium temperature exceeds +2000C it is expedient to use two-phase or three-phase induction motor with solid ferromagnetic rotor. There are presented the critical slip and maximum electromagnetic power expressions of the symmetric induction motor with solid ferromagnetic rotor taking into account the inner complex impedance of the power-supply source and the distributed parameters of the long geophysical cable. It has been proved that derived critical slip expression is the general case of a critical slip formula. The algorithm for the study of motor characteristics taking into account the parameters of the equivalent and the supply circuits is presented. Developed program gives possibility to compute the motor characteristics when it is placed in any borehole depth at various environment and borehole medium temperatures. Ill. 4, bibl. 4 (in English; summaries in English, Russian and Lithuanian.).

Effects of Slot Combination and Skewed Slot on the Electromagnetic Vibration of a 4-pole Capacitor Motor under Load Condition

Recently, the reduction of electromagnetic vibration and noise of a capacitor motor (CRM) has become a very important subject from the standpoint of environmental improvement. Therefore, the authors have studied the characteristics of the dominant electromagnetic vibration of the CRM under load condition. In this paper, the effects of slot combination and skewed slot on the dominant electromagnetic vibration of a CRM under load condition are discussed both theoretically and experimentally. As a result, the characteristics of the dominant electromagnetic vibration for the slot combination and the reduction effect of the skewed slot on the electromagnetic vibration are clarified for a 4-pole CRM.

The effect of interbar currents in a permanent split capacitor motor

This paper demonstrates how the techniques of generalized harmonic analysis may be applied to a permanent split capacitor (PSC) motor, allowing for the effects of interbar currents. The analysis is verified using an extensive set of experimental measurements made on a 2.5-hp two-pole motor, which show excellent agreement with calculation, provided an appropriate interbar current flow model is adopted.

Equivalent loading of induction motors using a new composite power supply with a linear (U/Hz) characteristic

This paper describes a mixed variable voltage magnitude variable frequency (VVMVF) power supply with linear U/Hz characteristic that can be used for equivalent loading of ac machines. The proposed voltage source ensures the rated air gap flux as well as forces the rated current (Irms) inside the test machine without the need to connect a mechanical load to the shaft. This means that the motor total losses essentially will be the same as under normal full load operation. A comparison is first made between those of equivalent loading schemes of induction machine that use the frequency and magnitude modulating voltage sources. Then the practical implementation of a 1.5 kW voltage source of the above mentioned type is presented which is achieved by series connection of a regular constant voltage and frequency source (the motor-rated source) and a special PWM inverter (auxiliary source), using an isolating transformer. The mixed single-phase source is used for synthetic loading of a capacitor start single-phase induction motor. Simulation and experimental results obtained are in close agreement. Copyright © 2006 John Wiley & Sons, Ltd.

Steady State Analysis and Simulation of PWM Inverter Fed Capacitor Run Induction Motor

This paper presents transient and steady state analysis and simulation of capacitor run Induction motor driven by Pulse Width Modulated (PWM) voltage source inverter. The d-q axes model of the motor is represented in the state-space form and is used for simulation study. Experimental results are provided to validate the simulation results.

Comparative Study of Starting Methods for a Single-Phase Permanent Magnet Synchronous Motor

This paper compares three starting methods for a single-phase interior permanent magnet synchronous motor. One is a line-start capacitor motor with a starting cage. The second is the same cage motor with an open-loop variable-voltage fixed-frequency inverter. The third uses the same motor without its starting cage, fed from a closed-loop current-regulated inverter with shaft position feedback. The computed starting performance is compared with test data for all three cases.

Causes and characteristics of the electromagnetic vibration of a capacitor motor under load

Capacitor motors (CRMs) are widely used to drive industrial equipment and home electric appliances. Recently, reduction of the vibration and noise of CRMs has become increasingly important from the standpoint of environmental improvement. However, electromagnetic vibration of CRMs under load has not been sufficiently analyzed. The present paper theoretically and experimentally discusses the causes and characteristics of CRM electromagnetic vibration under load. The primary conclusions are as follows: (1) The general formula for the dominant electromagnetic vibration caused by electromagnetic force waves was derived, including the influences not only of a backward magnetic field but also of magnetic saturation. (2) The dominant electromagnetic vibration of CRMs is theoretically attributed to three types of electromagnetic force waves. Two types of electromagnetic force wave are generated by the interaction of two forward magnetic fluxes, such as those of a three-phase squirrel-cage induction motor, and the other type of electromagnetic force wave is generated under the influence of a backward magnetic flux. (3) The characteristics of the dominant electromagnetic vibration depending on the load and the running capacitance are subdivided theoretically and experimentally into three types based on the characteristics of the electromagnetic force wave and the equivalent circuit current. (4) The influences of magnetic saturation in dominant electromagnetic vibration have been verified experimentally and their causes have been clarified theoretically in relation to electromagnetic force waves. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(4): 68–76, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20129

Line-start performance of single-phase synchronous reluctance motor with controlled capacitor

This paper reports the effect of values of starting and synchronisation (running) capacitors on the line-start performance of a single-phase cage-rotor synchronous reluctance motor. The d-q rotor reference frame dynamic equations were used to select the values of capacitors best suited for starting and running and it is shown that for a near-instantaneous starting, the capacitances should be varied (within the selected peaks) in line with the machine speed error. One single three-terminal capacitor device controlled by speed error signal is found to be very useful in realising a faster acceleration than obtainable with conventional and other known methods. Peak torque pulsations and current drawn by the main winding were found to be reduced, suggesting a more efficient motor drive performance. Simulated and experimental results bear a resemblance.

Comparison of sliding‐surface and moving‐band techniques in frequency‐domain finite‐element models of rotating machines

The sliding‐surface and moving‐band techniques are introduced in frequency‐domain finite element formulations to model the solid‐body motion of the rotors in an cylindrical machine. Both techniques are compared concerning their feasibility and computational efficiency. A frequency‐domain model of a capacitor motor is equipped with a sliding surface and compared to a transient model with moving band. This example illustrates the advantages of frequency‐domain simulation over transient simulation for the simulation of steady‐state working conditions of electrical machines.

Analysis and Performance Evaluation of Triac-Voltage Controlled Capacitor Run Induction Motor

This article presents steady-state analysis and simulation of triac-voltage controlled capacitor run single-phase induction motor driving a domestic fan load. Two schemes of circuits, namely, line controlled and branch controlled configurations, suitable for speed control are considered and simulation results are presented. Also, the two schemes are compared in terms of motor efficiency, line current pollution, and input power factor, keeping motor speed as the independent variable. It is shown that branch controlled circuit is superior in performance compared to line controlled one. Analytical, simulation, and experimental results are presented.

Two-phase induction motor drives

This article starts with a presentation of the mathematical model for an asymmetrical two-phase induction motor drives (TPIM). This is followed by an analysis of TPIM behavior under variable frequency supply, with the running capacitor placed or removed from the circuit. This article attempts mainly to investigate the reasons for the lack of variable-speed drives. Consequently, the aptitude of the TPIMs for operating at variable speed is to be estimated and the suitable power electronic topologies identified. The most common form of a typical two-phase machine is the permanent split-capacitor motor (PSCM), usually recognized as the single-phase induction machine.

Direct Measurement of Motor Excitation Force

The direct measurement method of motor excitation force was investigated using a test system with a capacitor motor and a load cell. First, the direct measurement method was analyzed by using a two-degrees of freedom system theoretically. Several analyses were performed to investigate the influence of the stiffness of the structure for supporting a motor. The calculation results indicate that the excitation force measured by a load cell is strongly influenced by the stiffness of the supporting structure. Next, the motor excitation force was measured using test system with a capacitor motor, a load cell, and a high-stiffness block. Furthermore, the test system, which was composed of the motor and a thin steel plate, was modeled by the finite-element model, and the vibration response was calculated by using the measured exciting force of the motor. And the calculated and measured vibration accelerations of the thin plate agree well.

Causes and Characteristics of the Electromagnetic Vibration of a Capacitor Motor under Load Condition

The capacitor motors (CRMs) are widely used to drive industrial equipment and electric home appliances. Recently, the reduction of the vibration and noise of CRMs has become increasingly important from the standpoint of environmental improvement. However, electromagnetic vibration of CRMs under load has not been analyzed sufficiently. The present paper theoretically and experimentally discusses the causes and characteristics of CRM electromagnetic vibration under load. The primary conclusions are as follows: (1) The general formula for dominant electromagnetic vibration caused by electromagnetic force wave was derived, including the influences not only of a backward magnetic field but also of magnetic saturation. (2) The dominant electromagnetic vibration of CRMs was theoretically attributed to three types of electromagnetic force waves. Two types of electromagnetic force wave are generated by the interaction of two forward magnetic fluxes, such as those of a three-phase squirrel-cage induction motor, and the other type of electromagnetic force wave is generated under the influence of a backward magnetic flux. (3) The characteristics of dominant electromagnetic vibration depending on load and running capacitor were classified theoretically and experimentally into three types based on the characteristics of the electromagnetic force wave and equivalent circuit current. (4) The influences of magnetic saturation in dominant electromagnetic vibration were verified experimentally and their causes were clarified theoretically in relation to electromagnetic force waves.

Modelling of single phase induction machines

This paper considers a novel model of a single phase, capacitor start induction motor that is based on the use of an ideal rotating transformer (IRTF). The model is an extension of the IRTF based model already used for modelling three phase and DC machines. The paper outlines the new model and discusses an application of the model. A TRIAC is connected in series with the machine as to allow control of the motor speed. Experimental and simulation results of the new model confirm the validity of the work carried out.

Revolving-field polygon technique for performance prediction of single-phase induction motors

This paper presents a new analytical technique for improving the performance prediction of single-phase induction motors, especially capacitor motors. The technique uses the split-phase motor electrical equivalent circuit analysis together with electrical and magnetic parameters whose variation is computed from the equivalent balanced polyphase motor, so that the same magnetic circuit analysis can be used for both. (The term split-phase is used to cover motors operating from a single-phase supply but with the phase windings split into two orthogonal windings, one of which may have a capacitor in series with it during running or starting.) The technique accounts for the elliptical envelope of the magnetizing field vector and results in improved precision, since the three-phase electromagnetic model is considered to be more precise than the normal split-phase motor analysis. An important result is the computation of vector polygons of flux density for each section of the magnetic circuit, providing a better basis for core loss prediction. The double-frequency torque ripple is also obtained from the stator magnetomotive force and flux-density polygons. Three different electrical equivalent circuit methods for the split-phase motor (based respectively on the cross-field theory, forward- and backward-revolving fields, and symmetrical components) are evaluated to determine the method best suited for incorporating the variation of the circuit parameters from the polyphase magnetic circuit analysis, and it is discussed how the core losses can be included in these circuits to obtain the best overall performance prediction.

PSPICE simulation of a capacitor start and triac start single phase induction motor during steady state and transient operations and its experimental verification : Faiz, J. et al. Energy Conversion and Management, 2003, 44, (3), 379–495

PSPICE simulation of a capacitor start and triac start single phase induction motor during steady state and transient operations and its experimental verification : Faiz, J. et al. Energy Conversion and Management, 2003, 44, (3), 379–495

Magnet shape optimization for high performance single-phase line start synchronous motor

This article presents an optimal design for a single-phase line start synchronous motor according to permanent magnet and flux barrier geometries. To explore the improved torque and efficiency over that of conventional single-phase induction motors for compressors, three types of magnet shape and flux barrier are introduced. A time-stepped two-dimensional finite-element method that considers the external running capacitor is used for analysis of the steady state characteristics. Counter electromotive force at the rated speed, Ld and Lq inductances, torque, and efficiency are calculated to optimize the shape of the magnet and the flux barrier. From the torque and efficiency characteristics taking variation of the load angle into consideration in the steady state, we can determine an optimal design for the permanent magnet and the flux barrier.

Electrostatically Levitated Ring-Shaped Rotational-Gyro/Accelerometer

This paper reports an electrostatically levitated inertia measurement system which is based on the principle of a rotational gyro. The device has several advantages: the levitation of the rotor in a vacuum eliminates mechanical friction resulting in high sensitivity; the position control for the levitation allows accelerations to be sensed in the tri-axis; and the fabrication of the device by a micromachining technique has the cost advantages afforded by miniaturization. Latest measurements yield a noise floor of the gyro and that of the accelerometer as low as 0.15 deg/h1/2 and 30 µG/Hz1/2, respectively. This performance is achieved by a new sensor design. To further improve of the previous device, a ring-shaped structure is designed and fabricated by deep reactive ion etching using inductively coupled plasma. The rotor levitation is performed with capacitive detection and electrostatic actuation. Multiaxis closed-loop control is realized by differential capacitance sensing and frequency multiplying. The rotation of the micro gyro is based on the principle of a planar variable capacitance motor.

磁性くさび適用によるコンデンサモータの歯脈動損低減効果に関する一考察

A rotating machine with a stator slot has an energy loss caused by pulsation of the magnetic flux density distribution in the air-gap part. This loss is called the tooth pulsation loss. The purpose of this paper is to discuss the mechanism of a decrease in the tooth pulsation loss achieved by the use of ferrite magnetic wedges. We chose a capacitor motor as an object of analysis. We propose a method for estimating the tooth pulsation loss from the induced voltage of a virtual coil placed on the rotor surface. By analyzing the induced voltage of a virtual coil, using harmonic analysis, we clarified the relation of the tooth pulsation loss to the number of stator slots and the magnetic characteristics of the wedge materials.

磁化容易軸不平衡固定子を用いた平面形パラメトリックモータの内側共通磁路幅と特性の関係

We earlier investigated a new type of parametric motor using a laminated iron core, and we showed that the output and efficiency of a prototype motor are comparable to those of conventional single-phase capacitor motors. This paper discusses the relation ship between the width of the inner ring core and the characteristics of a laminated core parametric motor using an asymmetric stator. Parametric oscillation was stabilized, and output and efficiency were significantly improved, by using an asymmetric stator shape.