Three-phase Windings Research Articles

A Position Error Correction Method for Sensorless Control of Dual Three-Phase Permanent Magnet Synchronous Machines

In this article, an online rotor position error correction method is proposed to eliminate the impact of parameter mismatch in sensorless control for dual three-phase (DTP) permanent magnet synchronous machines drives. The rotor position error production mechanism is first derived and shows that the error changes with the trend of current variation when there is a parameter mismatch. Based on this mechanism, by injecting sinusoidal current signals with low frequency and small amplitude into both sets of three-phase windings, the presence of parameter mismatch and its level can be revealed from the corresponding sinusoidal responses of the estimated speed of sensorless observers, which do not depend on the inertia of the machine. Since the amplitudes of these responses decrease as the parameter mismatch level reduces, with the help of the least mean square algorithm, the parameters can be adaptively adjusted to the actual values, and the position error can be thus corrected. Moreover, with the extra freedom of DTP machines, the detrimental effects on torque production due to current signal injections can be eliminated through adjusting the phase between the two injected signals. The effectiveness of the proposed method has been validated through simulation and experimental results.

A novel two-layer winding topology for sub-harmonic synchronous machines

With optimized design and modern brushless operation, wound rotor synchronous machines are resurrecting as a strong contender in many applications presently dominated by permanent magnet machines. Considering the notion, this paper introduces a novel brushless synchronous machine topology that utilizes sub-harmonic magnetomotive force (MMF) of its stator winding for desirable brushless operation. It is significant to state that the sub-harmonic MMF component that is used in this novel topology is one-fourth of the fundamental MMF component, whereas, in previous practices, it was half. Moreover, the stator of the machine uses a new winding arrangement of two sets of balanced three-phase windings wound in two layers to produce the fundamental and the sub-harmonic MMF. To achieve the brushless excitation, the rotor utilizes an additional winding that is used to induce the electromotive force (EMF) by the sub-harmonic MMF component of the stator. This novel two-layer stator winding topology permits the utilization of maximum allowable space in the stator to house conductors in all of its 48 slots, which was not the case in previous papers. To validate the performance, and feasibility, an 8-pole 48-slot brushless wound rotor synchronous motor is designed, and a 2-D finite element analysis simulation is conducted, where the topology shows immense potential in terms of better torque performance.

Novel Design of Six-Phase Spoke-Type Ferrite Permanent Magnet Motor for Electric Truck Application

This paper proposes a 300 kW 24-slot/10-pole 6-phase stator-shifted fractional-slot concentrated winding spoke-type ferrite permanent magnet machine for electric truck applications. The proposed motor consists of a stator with dual three-phase windings positioned 75 degrees apart to reduce higher-order MMF harmonic order, and a rotor with an inexpensive and high-resistance ferrite permanent magnet in the spoke configuration. The simulated result of the stator-shifted machine is compared with a fabricated stator-shifted machine, and the results show good agreement with each other. To further reduce the torque ripple from 2.5 to 0.9% while maintaining a high maximum torque of 2980 Nm, circular voids with a diameter of 11 mm are embedded in the rotor. The proposed motor is evaluated for irreversible demagnetization, mechanical and thermal stability, and fault tolerant ability. To assess the proposed motor performance, the electric truck simulation model is constructed using MATLAB/Simulink and used to compare with the reported 12-slot/10-pole rare-earth permanent magnet-based machine. Compared to a previously reported six-phase rare-earth permanent magnet based flat-type machine, the proposed motor can save 4.3 kWh of energy with a USD 2512 lower cost while retaining a similar motor performance.

Electromagnetic characteristic analysis of a REBCO magnet with a current bypass/distribution winding technique under an asynchronous rotating magnetic field

Generally, high-temperature superconducting rotating machines (HTSRMs) are considered synchronous machines. If the output of the HTSRM fluctuates based on frequent changes in the electrical or mechanical loads, there is the concern that an asynchronous rotating magnetic field (RMF) is applied from the stationary copper armature winding to the high-temperature superconducting (HTS) field winding in the rotary. This may act as a magnetic disturbance to the HTS field magnet, resulting in permanent damage. To enhance the reliability of HTS magnets in wind power and electric propulsion applications, winding methods with current bypass/distribution characteristics, such as no-insulation (NI) and metal-insulation (MI), have attracted scholarly attention because of their high thermal and electrical stabilities, resulting in their self-stabilizing and protective performances. To verify the feasibility of the NI and MI winding techniques for wind power generators, the basic characteristics under a time-varying magnetic field must be studied, contrary to HTS magnet applications under a time-static magnetic field. Therefore, the electromagnetic characteristics of rare-earth barium copper oxide (REBCO) magnets applied with NI and MI winding technologies were compared and analyzed in this study, considering the magnetically transient situations in which an asynchronous RMF is applied to REBCO magnets. In addition, we developed a characteristic evaluation device similar to a synchronous rotating machine to generate the unsynchronized RMF. Moreover, various basic tests were performed to target the small racetrack-type field windings. The critical current, n-value, terminal voltage, and center magnetic field are investigated under various values of the frequency and current amplitude of the three-phase armature winding, and their behaviors are discussed in detail based on the characteristic resistances of the two test magnets.

Conceptualization and Efficiency Review of Integrated Chargers Using Six-Phase Machines

Three integrated battery charger concepts based on six-phase electrical machines (EMs) are presented in this article. State-of-the-art topologies for galvanically isolated integrated chargers are reviewed as a basis for a novel integrated charger using the electrical drive (e-drive) as an isolated dc/dc converter, while the rotor is kept at standstill. Efficiency levels up to 88% and a cost breakdown are reported. Furthermore, the well-known reconfigurations of three-phase machines are reviewed and proposed as a basis for novel series-connected boost–buck converters, in which each stage is represented by one of the two three-phase machine windings and power electronic converters. The efficiency analysis of a 144-kW e-drive under this 6.6-kW dc biased battery charging condition is presented. The EM iron losses are calculated with finite-element method (FEM) using new Steinmetz parameters based on ring core measurements reflecting charging conditions. In addition, the dc and ac copper losses are analytically calculated. Moreover, inverter losses are analyzed based on their own switching loss measurements. The calculated efficiency of the integrated charger is compared with measurement results. The difference in efficiency between both remains within ±1% and efficiency levels up to 93% are reported. Finally, silicon carbide technology shows enhanced efficiencies.

General Current Control of Six-Phase-Based Non-Isolated Integrated On-Board Charger with Low Order Harmonic Compensation

Electric vehicle charging technology has recently witnessed massive developments due to its significant role in the ever-growing number of electric vehicles on the market. The integrated on-board charger technology (IOBC) represents an effective and attractive solution to reduce EV size, cost, and weight. IOBC technology employs propulsion components, such as the motor and its converter, in the charging process. The main objective of IOBC is to achieve the maximum charging current with zero average/pulsating torque so that mechanical interlocking can be dispensed. Recently, some of the IOBC topologies have adopted machines with six-phase stators to exploit the many advantages of multiphase-based systems. This paper investigates the effect of the winding design, namely, chorded or un-chorded designs, as well as the winding configuration, namely, dual three-phase, asymmetrical, or symmetrical winding configurations, on the current quality of a six-phase-based non-isolated IOBC. The relation between the winding design and the induced low order harmonics in the charging current is first clarified. The required current controller structure is then proposed, which ensures balanced grid line currents with high quality, under either healthy or one-phase fault conditions. Finally, a comparative study between all available designs with the proposed current controller is carried out to validate the theoretical findings.

Coupled Magnetic Field and Thermal Analysis Model for an IPMSM With Modular Three-Phase Winding Topologies for Fault-Tolerant Applications

Multi three-phase machines are frequently recommended for high current and high power applications due to their ability to minimize phase current while maintaining rated power and phase voltage. Furthermore, multi three-phase machines are also proposed because of their fault-tolerant capability to operate in partial working conditions due to their redundant structure. A partial working condition may occur when one or more three-phase winding sets go into faulty condition. This article focuses on evaluating the thermal behavior and efficiency of a multi three-phase machine comprising different modular winding topologies to investigate its normal, partial, and partially overloaded operation. The machine prototype used in the analysis is an interior permanent magnet synchronous machine (IPMSM) having six three-phase winding sets configured in modular three-phase winding arrangements. Firstly, the prototype machine’s losses, efficiency, and output torque performances are evaluated through electromagnetic finite element analysis (FEA) for the different modular three-phase winding topologies applying similar operating conditions. Then the machine’s thermal behavior is evaluated for the modular (concentrated, distributed, and combined concentrated and distributed) three-phase winding topologies through a coupled magnetic field and thermal analyses under the machine’s healthy, partial, and partially overload operations. Finally, a comparative thermal analysis is presented for the machine prototype along with experimental validations for the analyzed modular three-phase windings topologies. This research study suggests the best modular three-phase winding topology for a multi three-phase machine considering efficiency performance and mutual heat exchange phenomenon between different three-phase independent winding sets, particularly for the machine’s partial and partially over-load working conditions.

Определение минимального числа витков катушек вторичной обмотки трансформаторного трехфазно-многофазного преобразователя числа фаз

The article has considered an approach to determining the minimum of the secondary winding coils turns of a transformer three-phase-multiphase phase number converter. Each phase of the secondary winding of the considered converter consists of three coils connected in series placed on three different rods of the magnetic circuit. In order to solve the optimization problem, the interior-point method is used. As an example, for a three-phase-five-phase converter has determined the minimum number of turns of the secondary winding, the total power consumed by the coils of the secondary winding is calculated. A vector diagram EMF of the coils of the secondary winding is constructed, explaining the formation of a symmetrical five-phase EMF system at the terminals of the secondary winding. Using the proposed approach, it is possible to design a transformer converter of the number of phases with a three-phase primary winding and a multiphase secondary winding, the number of phases of which is more than two.

２次元リニア同期モータの直交する交番磁界によるz軸360°回転駆動の検討

We aim to develop an X–Y linear synchronous motor where 360° rotational motion around the Z-axis is possible. We considered “rotational force characteristics around the Z-axis that use alternating magnetic fields orthogonal to the X–Y linear synchronous motor.” The stator of the linear synchronous motor has two pairs of three-phase field windings positioned orthogonally to each other. A two-pole permanent magnet and an iron core comprise the rotor (mobile element). We demonstrated the rotating magnetic field around the Z-axis generated by an alternating magnetic field intersecting on a plane. Further, we used magnetic field analysis to evaluate the rotational force characteristics working on the rotor. We also considered the impact of the position of the rotor magnetic pole on the output characteristics. We experimented with a prototype to evaluate the validity of the analytical result. The experimental result showed that a rotational drive force could be generated 360° around the Z-axis.

Novel Hybrid Consequent-Pole Brushless Wound Rotor Synchronous Machine for Improving Torque Characteristics

This article introduces a hybrid consequent-pole brushless wound rotor synchronous machine (CP-BL-WRSM). The CP-BL-WRSM installs permanent magnets (PMs) on the alternative rotor poles. Compared with the conventional BL-WRSM and permanent magnet-assisted brushless WRSM (PM-BL-WRSM), the proposed machine provides advantages of high average output torque, high maximum torque, and high starting torque. In addition, the proposed CP-BL-WRSM’s torque ripple is also lower than the conventional brushless WRSM. The volume of PM in the CP-BL-WRSM machine is lower than the conventional permanent magnet synchronous machines (PMSMs) and PM-BL-WRSM. In this brushless topology, the machine uses three-phase stator windings powered by a single inverter, which provides a unique armature current to the stator windings that comprises of fundamental and third-harmonic components. The fundamental current component is used to generate the main stator field, and the third-harmonic current component is used to induce a harmonic current in the harmonic winding. A diode rectifier installed on the rotor is used to rectify the harmonic current. After the rectification, a direct current (DC) is injected into the field winding of the rotor to form a rotor magnetic field and achieve brushless operation. In order to verify the operation of the proposed CP-BL-WRSM topology and analyze its performance, 2-D finite element analysis (FEA) was used in JMAG-Designer. Finally, the performance of the proposed CP-BL-WRSM topology was compared with the conventional BL-WRSM topology and PM-BL-WRSM topology to verify its higher starting torque, higher average torque, and higher maximum torque and higher minimum torque. The proposed topology can replace the existing highly expensive PM synchronous machines (PMSMs) due to its less PM volume and conventional BL-WRSMs due to its better performance.

Control of a six-phase synchronous reluctance motor

The results of the research on control of high-speed and lowspeed six-phase synchronous reluctance motor are presented in this paper. Two control variants of SynRM are considered: two galvanically isolated three-phase windings and one six-phase winding connected in the wye. The mathematical description, mathematical models, and results of synthesis of control systems for two considered variants of control of SynRM are given. The problems encountered by the authors are considered and the ways of their solution are presented. The results of practical research and comparison of the variants considered in controlling six-phase SynRM are presented. Conclusions about advantages and disadvantages of various control variants of a SynRM are made on the basis of theoretical and practical research and the obtained results. The presented results of mathematical description and synthesis of control system and also results of experimental research at control of prototypes of SynRM can be used at synthesis of control systems of any types of multiphase electric machines.

ВЕКТОРНОЕ УПРАВЛЕНИЕ ЭЛЕКТРОПРИВОДОМ НА ОСНОВЕ ВЕНТИЛЬНОГО ДВИГАТЕЛЯ С ДИСКРЕТНОЙ КОММУТАЦИЕЙ ОБМОТКИ

The article considers the possibility of implementing phase vector control (FVU) of a synchronous motor with permanent magnets in the thyratron motor mode. The characteristics of the FVU with three methods of discrete commutation of the three-phase winding are considered: six-stroke 120- and 180-degree and twelve-stroke 150-degree. A comparative assessment of the efficiency of the PVF is carried out in terms of expanding the range of implemented mechanical coordinates and energy indicators, both with different methods of discrete switching and with respect to sinusoidal power supply. It is shown that 120-degree switching is the most advantageous in terms of energy indicators. However, with it, the values of the maximum achievable speeds and moments weakly depend on the angle of commutation θ, therefore, operation is recommended at a constant θ = 0, corresponding to the efficiency value close to the maxi­mum in a wide range of speeds. With 180-degree commutation, the FVU allows you to adjust both the maximum speed and the maximum torque. However, with small values of the relative inductance of the winding, which refers to the ratio of inductive resistance to active, this method of regulation is ineffective due to low efficiency and is inferior in this indicator to both 120-degree commutation and the case of sinusoidal power supply. As the relative inductance increases, the difference between the case of sinusoidal power supply and 180-degree switching decreases. The use of 150-degree commutation allows, on the one hand, to increase efficiency while maintaining the ability to adjust coordinates, on the other hand, reduces the pulsation of the motor torque, expanding the possible scope of the drive.

Evaluation of Magnetomotive Force and Torque Ripples in Modular Type IPMSM With Multi Three-Phase Winding Configurations

Evaluation of Magnetomotive Force and Torque Ripples in Modular Type IPMSM With Multi Three-Phase Winding Configurations

Design and motion analysis of a small motor stator multi-wire paralleled winding hybrid robot

Abstract. The working space of small motor stators is narrow, and most of them are manual winding. It is difficult to guarantee the uniform arrangement of enameled wires by multi-wire winding. To solve these problems, a three-phase parallel equivalent multi-wire winding robot is proposed to achieve large output torque of the motor. Firstly, according to the equivalent model, the structure of the large arm, small arm and manipulator is designed to determine the motion model of the winding robot. Euler's kinematics theory is used to analyze the change of the working position of the arm, and the rotation matrix of the arm and the constraint equation of the motion vector of each branch chain are established. The motion model of the arm and the manipulator are established using inverse kinematics and analytical analysis. The motion pose of each joint of the winding robot is studied to ensure that the robot realizes a three-phase parallel multi-wire winding motion. ADAMS software was used for kinematic simulation analysis of the winding robot. The displacement of the branch chain on the xyz axis was represented by the torque of the virtual motor to verify the correctness of the inverse kinematics solution and the closure condition of the manipulator block. Finally, the ROS simulation platform is built to simulate the joint motion planning of the winding robot to verify the multi-line parallel principle and the feasibility of the multi-line parallel winding hybrid robot. The research results of this paper provide a theoretical reference for multi-wire parallel winding equipment control.

SOFTWARE MODULE FOR DESIGNING THREE-PHASE ROTARY ELECTRIC MACHINE WINDERS

The paper presents a software module developed that allows the design of windings for three-phase alternating current rotary electric machines. Starting from some initial data such as the number of pairs of poles and the number of notches per pole and phase, we obtain the diagram of the three-phase winding with diametric pitch, in a layer and integer number of notches per pole and phase. The program provides the designer in addition to the notched distribution of the coil sides, the relative distribution of the solemnity and the star of the notches.

Simulation-Assisted Design Process of a 22 kW Wireless Power Transfer System Using Three-Phase Coil Coupling for EVs

The objective of this paper is to study a 22 kW high-power wireless power transfer (WPT) system for battery charging in electric vehicles (EVs). The proposed WPT system consists of a three-phase half-bridge LC–LC (i.e., primary LC/secondary LC) resonant power converter and a three-phase sandwich wound coil set (transmitter, Tx; receiver, Rx). To transfer power effectively with a 250 mm air gap, the WPT system uses three-phase, sandwich-wound Tx/Rx coils to minimize the magnetic flux leakage effect and increase the power transfer efficiency (PTE). Furthermore, the relationship of the coupling coefficient between the Tx/Rx coils is complicated, as the coupling coefficient is not only dominated by the coupling strength of the primary and secondary sides but also relates to the primary or secondary three-phase magnetic coupling effects. In order to analyze the proposed three-phase WPT system, a detailed equivalent circuit model is derived for a better understanding. To give a design reference, a novel coil design method that can achieve high conversion efficiency for a high-power WPT system was developed based on a simulation-assisted design procedure. A pair of magnetically coupled Tx and Rx coils and the circuit parameters of the three-phase half-bridge LC–LC resonant converter for a 22 kW WPT system are adjusted through PSIM and CST STUDIO SUITE™ simulation to execute the derivation of the design formulas. Finally, the system achieved a PTE of 93.47% at an 85 kHz operating frequency with a 170 mm air gap between the coils. The results verify the feasibility of a simulation-assisted design in which the developed coils can comply with a high-power and high-efficiency WPT system in addition to a size reduction.

Voltage Sensorless Control of Split Capacitor for Three-Phase Four-Wire Motor System With Zero-Sequence Suspension Winding

This article aimed to simplify magnetically levitated motor system by implementing the voltage sensorless control of the split capacitor potential for a three-phase four-wire motor system with a zero-sequence suspension winding. In the system, the suspension winding for magnetic suspension is connected between the neutral point of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Y</i> -connected three-phase motor winding and the midpoint of two capacitors of direct-current (dc) link, thereby enabling simultaneous control of a three-phase interior permanent magnet synchronous motor and an axial magnetic bearing (iron-ball magnetic suspension, in this article), with only six power switches. However, the split capacitor potential is unbalanced by the dc component of the zero-sequence current, owing to the offset detection error of the current sensor and the bias current of the magnetic suspension. For suppressing the imbalance, we propose a voltage sensorless control. In the proposed method, the split capacitor potential is controlled without voltage detection by utilizing the zero-sequence voltage reference in the controller. The experimental results demonstrated that the split capacitor potential was successfully balanced while the iron-ball magnetic suspension and motor drive were performed. For further improvement of voltage sensorless control, a simplified control system was configurated with a filter controller based on an equivalent block diagram. The results indicated that the use of the filter controller improved the positioning accuracy of the magnetic suspension for the sensorless control system.

Performance Evaluation of a Homopolar Bearingless Motor for Ultrahigh Speed Applications

This study evaluates the performance of a homopolar bearingless motor driven at 100 000 r/min with a mechanical output power of 120 W. The rotor has two salient iron core parts assembled into the shaft in tandem. The stator comprises two units located axially in tandem and an axially magnetized permanent magnet that is sandwiched between these two stator units. This magnet provides three-dimensional magnetic bias flux to polarize the rotor core parts, resulting in single polarity of one rotor core; thus, this type of motor is called homopolar motor. Each stator has two separated three-phase windings for the motor rotation and magnetic suspension, and the bearingless motor examined in this study has active suspension control with four-degrees-of-freedom (radial and tilting motions). The rotating part consists of only iron cores, and hence, it has the advantage of a rigid robust structure. Additionally, no angle detection is needed for the active magnetic suspension control. Therefore, the homopolar bearingless motor is suitable for high-speed applications. The conventional homopolar bearingless motors have an eight-pole rotor, but the proposed structure has a six-pole rotor to reduce the driving electrical frequency. Although this six-pole homopolar bearingless motor has 20% suspension force variation and 4.5° of force error angle, the rotor is driven up to 100 000 r/min without touchdown. This study presents the structure and principle of the proposed homopolar bearingless motor and the experimental results of the load test.

Development of Axial-Flux Single-Drive Bearingless Motor With One-Axis Active Positioning

This study proposes a novel axial-flux bearingless permanent magnet motor with one-axis active positioning. This bearingless motor consists of an axial-flux surface permanent magnet motor with coreless coils and a repulsive permanent magnet coupling located at its center. Therefore, it has a single three-phase winding and needs only one three-phase inverter for both rotation and magnetic suspension; it is, thus, referred to as a single-drive bearingless motor. The axial position of the rotor is actively controlled, whereas the radial and tilting motions are passively stabilized. The suspension force and torque are regulated by the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> -axis and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis currents, respectively. The structure of the proposed axial-flux single-drive bearingless motor is presented, and its torque and suspension force are obtained by both theoretical derivation and numerical modeling (using the finite-element method). A prototype machine is fabricated, and the obtained experimental results are presented and discussed.

Cost-Effective Scheme for a Brushless Wound Rotor Synchronous Machine

This paper proposes a new scheme for a brushless wound rotor synchronous machine (WRSM) by generating an additional, two-pole component of magneto-motive force (MMF) with a series-connected additional three-phase winding with the armature three-phase winding. Unlike existing brushless excitation schemes, which use the inverter to inject harmonic currents in the stator windings, the proposed scheme uses series-connected additional winding on the stator with the armature winding in a two-pole configuration. Consequently, as the current flows in the armature winding, it creates a fundamental rotating air gap flux to interact with the field flux. At the same time, additional rotating flux is created from the additional three-phase winding, which cannot synchronize with the field winding. This additional flux can cause the induction of a voltage in a winding with exactly the same number of poles. For this purpose, a harmonic winding is installed in the rotor along with the field winding connected through a diode bridge rectifier, in order to feed the direct current (DC) to the field winding for rotor excitation without an input current from the brush-slip-ring assembly. The 2D finite-element analysis (FEA) was performed to validate the brushless operation of the proposed machine system.