Two-phase Excitation Research Articles

Micro-Stepping Motor for Instrument Panel Using PWM Drive Method

This study presents a pointer-driven controller for an instrument panel. The proposed pointer utilizes the permanent magnet (PM) stepping motor produced by the Japanese company NMB. This stepping motor is vibration-proof and tolerates noise jamming as well as wind and rain exposure. Moreover, it has no mechanical structures and is low cost. Most importantly, it features accurate positioning; therefore, it can be used to measure vehicle speed, engine speed, fuel capacity, and temperature. However, the PM stepping motor of the NMB pointer requires 10 degrees for each step, and this low resolution results in roll hesitation as its steps. The aim of the current paper was to solve the problems of the large angle size and low resolution associated with this stepping motor. Based on two-phase excitation, we propose driving the motor using pulse width modulation (PWM). Specifically, we divided each 10-degree step into 100 equal parts. In other words, every step is 0.1 degrees. The resolution of pointer rotation can be increased by 100-fold by using the approach proposed in this paper. When applied to vehicle (or locomotive) instruments, the pointer can move very smoothly on the tachometer or oil gauge.

Two-Phase Stator Vibration Amplitude Compensation of Traveling-Wave Ultrasonic Motor

The consistency of the two-phase mode responses is essential to ensure the mechanical performance and stability of traveling-wave ultrasonic motors. Due to the asymmetry of the stator, inevitable manufacturing errors, or imbalance of the excitation voltages, the amplitudes of the two-phase standing waves cannot be exactly the same, resulting in unstable operating of USM. To improve the stability of the motor and decrease the velocity fluctuation, a closed-loop velocity control scheme considering two-phase consistency compensation based on the vibration amplitude of the stator is proposed. This scheme is implemented under the framework of the stator vibration amplitude-based velocity control and parallel resonance frequency tracking (VCBVF). Based on the relationship between the velocity and stator vibration amplitude (SVA), two-phase excitation signals are adjusted individually and simultaneously. Compared with the single-phase feedback VCBVF control scheme, experimental results show that the proposed scheme can reduce the overshoot from 17.50% to 6.90% and velocity fluctuations from 7.69 rpm to 2.40 rpm, under different load torques. The proposed scheme can compensate for the two-phase electrical inconsistency and improve the velocity stability and output power of motor operation under various conditions.

A Micro Piezoelectric Motor With Multiple Excitation Modes and Methods

To widen the performance of piezoelectric motors, this paper demonstrates a micro piezoelectric motor having multiple driving ways. The stator includes a hollow polygon bar and two groups of PZT plates. PZT plates are symmetrically bonded onto a brass base, and used to actuate the vibration modes of the stator. The symmetrical design enables the motor to operate in two types of vibration modes. The working modes are the second/third-order in-plane bending modes, and can be excited by different ways. Elliptical motion of stator surface points is generated by superposition of two bending modes with the same order. To investigate the feasibility of multi-mode and multi-motivation mechanisms, vibration behaviors of stator driving particles are simulated using ANSYS software. The structural parameters of the stator are strictly designed to harmonize the eigenfrequencies of the vibration modes. The calculated results reveal that the motor performance can be adjusted by selecting different operating modes and excitation ways. The motor performances under various excitation ways and driving modes are also investigated experimentally to validate the proposed design. The dimension of the fabricated prototype motor is 8.3 mm$\times 7.2$ mm$\times 15.0$ mm. The maximum torques are respectively 8.3 cN$\cdot \text{m}$ and 13.3 cN$\cdot \text{m}$ under single-phase and two-phase excitation voltages, when the motor operates in the second-order bending modes. The corresponding no-load speeds are respectively 40 rpm and 47 rpm. The maximum torque and speed under the third-order bending modes are much smaller than that under the second-order bending modes.

Modified switching scheme‐based explicit torque control of brush‐less direct current motor drive

A modified explicit torque control (ETC) scheme for permanent magnet (PM) machine with non-sinusoidal back emf is investigated in this article. The conventional ETC scheme for the PM machines with non-sinusoidal back emf furnishes a wide band for the switching frequency and offers a faster response in the torque. In this article, a modified scheme for switching vector selection is proposed to reduce the switching frequency while maintaining the advantage of faster torque response. Other than the conventional two-phase excitation, which uses opposite vectors for switching to get the speedier response in torque, the modifications proposed for the ETC of PM machine are (i) a closer vector selection from the available two-phase vector plane and (ii) a combination of two phase and three phase excitation. Both these modifications gives a faster response in the torque as that of conventional ETC, while this offers a reduction in the switching frequency. Switching frequency variations are expressed mathematically, and experimental results are presented for the modified schemes of ETC and for the conventional ETC based to validate the proposed scheme.

Torque ripple reduction in brushless wound rotor synchronous machine by two-phase excitation winding

Torque ripple reduction in brushless wound rotor synchronous machine by two-phase excitation winding

Investigation of Static Characteristics in Six-Phase Switched Reluctance Motors under Different Winding Connections

The effect of the winding connections on the static torque in six-phase switched reluctance motors (SRMs) is investigated in this paper. Different winding connections for the six-phase SRMs are shown and compared. Under the conditions of different winding connections, the self-inductance and mutual inductance of a six-phase SRM are compared and analyzed. Six-phase SRMs can be running in two-phase excitation mode and three-phase excitation mode, and in these two modes, the static torque characteristics with different poles polarities arrangements are compared and analyzed. The comparison of the static torque in a six-phase SRM with different winding connections is obtained by the Maxwell 2D and experiments. Based on the results, an optimal winding connection mode for starting stage of the six-phase SRMs is proposed.

Research on the planar‐coil linear time grating

This article proposes a planar-coil linear time grating displacement sensor. Compared with the existing magnetic field-type linear time grating, the structure without tooth and slot improves the velocity uniformity of travelling wave magnetic field and the measurement accuracy can be greatly improved. The two-phase excitation coils are arranged to form a plane coil array, and the travelling wave magnetic field is generated after the two-phase orthogonal signals are entered, respectively. Then, the electric travelling wave signal is induced by the pickup coils, and the displacement is obtained after processing. The signal processing circuit is designed to amplify and filter the electric travelling wave signal, and the accuracy experiment is carried out. Result shows that in the range of 240 mm (full-scale), the measurement accuracy can achieve ±0.8 μm.

Characteristics analysis of a plate type linear piezoelectric actuator based on a point contact model

A point contact model is developed to analyze the fundamental characteristics of a single-mode actuation type linear piezoelectric actuator in this paper. The prototype is a plate type piezoelectric actuator using two-phase excitation, which realizes bi-directional motion by changing the vibration mode within different exciting frequencies. Differs from other models, the vibration of barycenter of the stator is taken into account, and the trajectories of driving tip are simulated and measured with and without consideration of the mechanical contact. The results show that a spiral reciprocating motion is generated at driving tip while taking into account the contact and vibration of barycenter of stator. Furthermore, the contact state between the driving tip and linear guide is analyzed by discussing the influence of some important factors including preload and exciting voltage. In addition, the behavior of the force transmission between the driving tip and linear guide is investigated via the classic coulomb friction model to understand the drive mechanism of the single-mode actuation type actuator. Finally, the relations between the output speed and various inputs to the actuator are studied by numerical simulations, which are validated by experiments. It is shown that experimental results are in good agreement with simulation results, which verifies the effectiveness of the proposed model.

Multi‐objective optimisation design of two‐phase excitation switched reluctance motor for electric vehicles

Compared with the single-phase excitation mode of the switched reluctance motor (SRM), the statictorque curves of the SRM with two-phase excitation mode are more flexuous andwide flat regions are absent from the curves. To improve the static torqueperformance of the SRM with two-phase mode, geometrical multi-objectiveoptimisation strategy is developed in this paper. Considering the requirementsof the electric vehicles, four indicators are presented and defined to evaluatethe development of the SRM. Six main independent variables are determined and anovel multi-objective optimisation function was proposed to simultaneouslyimprove static performance of the SRM. Furthermore, to simplify theoptimisation, a sensitivity index that reflects the relative importance of eachvariable is developed to eliminate insignificant variables. The four-phase 8/6SRM with two-phase mode is optimised by means of the proposed multi-objectiveoptimisation method based on effects and sensitivity analysis of the designvariables on indicators. The static and dynamic torque performance of theoptimised SRM is evaluated and compared with those of the initial motor. Thecomparison results show that the multi-objective simultaneous optimisationstrategy can improve the static average torque, static average torque per mass,and global index by 18.09, 12.08, and 6.57%,respectively.

Development and Analysis of a Two-Phase Excitation Switched Reluctance Motor with Novel Winding Distribution Used in Electric Vehicles

Development and Analysis of a Two-Phase Excitation Switched Reluctance Motor with Novel Winding Distribution Used in Electric Vehicles

Position sensorless technology of switched reluctance motor drives including mutual inductance

To reduce the effect of estimation position angle error caused by mutual inductance on sensorless control of switched reluctance motor (SRM) in clear command channel mode, a SRM rotor position estimation method is presented. Using this method, the effect of mutual inductance can be eliminated without measuring mutual inductance. First, different working states are analysed. When working at single-phase excitation, mutual inductance can be ignored, inductance model method is used to estimate the position angle. When working at two-phase excitation situation, mutual inductance is non-zero, based on flux linkage-difference a new method is used to eliminate mutual inductance influence. Finally, the proposed method is verified by experiments. Experiment results show that compared with the mutual inductance ignored methods, the proposed method has higher estimation accuracy. This method can realise stable and reliable running of SRM sensorless control in wider speed range.

Linear Model of a Novel 5-Phase Segment Type Switched Reluctance Motor

This paper introduces the general linear magnetic circuit model of a novel 5-phase segment type switched reluctance motor (ST-SRM) of which rotor cores are embedded in an aluminum block as well as to improve the performance characteristics under simultaneous two-phase (bipolar) excitation of windings. The developed model implements the magneto motor force (mmf) that is necessary to produce short and exclusive magnetic flux paths minimizing the commutation switching and eddy current losses in the laminations. For this purpose, an equivalent magnetic circuit for newly developed ST-SRM and the underlying assumptions are given. The concept of apparent inductance and torque equations of two-phase simultaneously excited ST-SRM is introduced and the effectiveness and deficiencies of the linear model are given. DOI: http://dx.doi.org/10.5755/j01.eee.20.1.6159

Improved decoupled model of mutually coupled dual‐channel SRM with consideration of magnetic saturation in dual‐channel operation

This study proposes an improved decoupled model of mutually coupled dual-channel switched reluctance machine (DCSRM) based on the equivalent inductance and flux linkage characteristics that consider magnetic saturation in dual-channel operation (DCO) mode. A three-dimensional finite-element analysis (FEA) is used to calculate the static phase equivalent inductance of DCSRM for the simultaneous two-phase excitation with consideration of saturation. And an indirect experimental test is performed to measure the equivalent flux linkage under the simultaneous two-phase excitation and compared with the FEA results. In this improved decoupled model, the phase equivalent inductances and flux linkages in each channel are independent to each other and separately expressed as a function of rotor position and their own phase current. The static magnetic characteristics, details of modelling procedure and performances prediction for the DCSRM under DCO mode without and with consideration of saturation are compared. Finally, an experimental set-up for a 12/8 DCSRM drive system based on dSPACE is built and the simulation and experimental results are compared, which verifies high accuracy of this improved modelling method.

A Novel Two-Phase Permanent Magnet Synchronous Motor Modeling for Torque Ripple Minimization

This paper proposes a novel two-phase, two-pole, permanent magnet synchronous motor (PMSM) with dual U-core stator structure for torque ripple minimization. The proposed motor is modeled based on the conventional single-phase U-core PMSM with approximate output power and core dimension. Torque ripple in the novel motor can be reduced significantly due to 90 $^{\circ}$ electrical angle phase shift in two sets of magnet pairs and 90 $^{\circ}$ shift in two-phase excitation currents. Characteristics of both PMSMs such as back-EMF, cogging torque and electromagnetic torque are analyzed and compared by using the 3-D finite element analysis (FEA). As shown in the result, the cogging torque and torque ripple in the novel two-phase PMSM are efficiently reduced with sinusoidal back-EMF waveform and reasonable current density value. The validity of both PMSM models is also verified by the comparison between simulated and experimental measured results.

Modeling of the Power Factor Correction of 8/6 Poles Switched Reluctance Motors

In the traditional power topology structure of switched reluctance motor (SRM), the ideal DC bus voltage is supplied by the circuit which is composed by a rectifier bridge and a filter capacitor. The capacitor is usually large to reduce the torque ripple, so the conducting time of AC source is very short and the power factor is reductive. A novel power topology structure of SRM is presented in this paper, and it is applied to the traditional split-phase structure to carry out power factor correction (PFC). This paper sets up the two-phase simultaneous excitation of four phases 8/6 poles SRD based on MATLAB/SIMULINK, and analyzes the current, voltage, torque etc. of two-phase excitation. The simulation results proves that the novel topology is not only improving the power factor but also optimizing the motor starting performance and efficiency, and it provides a feasible way for the study of energy conservation and efficient SRM.

A novel rotor position estimation approach for an 8/6 solid rotor switched reluctance motor

Switched reluctance motor (SRM) is becoming popular due to its simple construction, low manufacturing cost, ruggedness and fault-tolerant capability. In conventional switched reluctance motor (SRM), rotor is laminated. But in solid rotor switched reluctance motor (SRM), rotor is not laminated, and it is suitable for applications where rotors are immersed in water environment. A stationary can arrangement is introduced between stator and rotor. In this research, an 8/6 solid rotor switched reluctance motor which is used in reactivity control mechanisms of nuclear reactors is considered as test motor. As solid rotor switched reluctance motor is suitable for working in water environments in nuclear reactors, rotor position estimation is the topic of interest. A new approach which adopts two-phase excitation method is presented for rotor position estimation. Four different artificial neural networks (ANNs) with 2-5-5-1 structure are trained to estimate rotor position. The main advantage of this approach is to minimize the required number of voltage and current sensors. The validity of the new approach is verified through online comparison of estimated and actual rotor position.

Speed control of switched reluctance motors taking into account mutual inductances and magnetic saturation effects

Abstract This paper deals with the speed control of switched reluctance motor (SRM) drives taking into account the effects of the mutual inductances between two adjacent phases and the effects of the magnetic saturation of the core. To overcome the problems commonly associated with single-phase excitation, a nonlinear SRM model, which is suitable for two-phase excitation and which takes into account the effects of mutual inductances between two adjacent phases and the magnetic saturation effects, is considered in the design of the proposed controllers. A feedback linearization control scheme and a sliding mode control scheme are designed for this motor drive. The proposed controllers guarantee the convergence of the phase currents and the rotor speed of the motor to their desired values. Simulation results indicate that the proposed controllers work well and that they are robust to changes in the parameters of the system and to changes in the load torque.

Nonlinear Speed Control of Switched Reluctance Motor Drives Taking into Account Mutual Inductance

A speed control algorithm is proposed for variable speed switched reluctance motor (SRM) drives taking into account the effects of mutual inductances. The control scheme adopts two-phase excitation; exciting two adjacent phases can overcome the problems associated with single-phase excitation such as large torque ripple, increased acoustic noise, and rotor shaft fatigues. The effects of mutual coupling between two adjacent phases and their contribution to the generated electromagnetic torque are considered in the design of the proposed control scheme for the motor. The proposed controller guarantees the convergence of the currents and the rotor speed of the motor to their desired values. Simulation results are given to illustrate the developed theory; the simulation studies show that the proposed controller works well. Moreover, the simulation results indicate that the proposed controller is robust to changes in the parameters of the motor and to changes in the load torque.

Dynamic Analysis of One-Link Robot Arm Driven by Stepping Motor Using Microstep Drive and Harmonic Reduction Gear

In this paper, first, taking into consideration stepping motor torque and harmonic reduction gear flexibility, the equations of motion of a one-link robot arm driven by a harmonic reduction gear and a hybrid stepping motor using a microstep drive are derived. The stepping motor is excited by two-phase excitation. Then, the numerical simulations of the one-link robot arm's dynamic response for four-division microstep and full-step drives have been carried out, and it is confirmed theoretically that the amplitudes of the vibrating torque of the stepping motor for the microstep drive are considerably smaller than that for the full-step drive, and the transient vibrations of the stepping motor in acceleration and deceleration periods can be reduced using microstep drive. Furthermore, the experiments of the trajectory tracking control of the one-link robot arm have been carried out, and the effects of the microstep drive on the transient vibration reduction of the stepping motor are demonstrated.

Initial Position Estimation for Closed-Loop Linear Hybrid Stepping Motor Drives Using DC Excitation

This paper presents a simple and economical way to accurately estimate an initial position for linear hybrid stepping motor (LHSM) drives by utilizing dc excitation. In order to detect an absolute position of the mover, two preliminary tests are carried out under two different dc conditions: single-phase and two-phase dc excitation. The proposed algorithm has been successfully applied to a practical system with a rated initial load and stiction without causing any mechanical damage. The proposed scheme is not affected by the harmonic force ripple of the LHSM and its benefits are much more significant for multi-axis systems. The paper presents experimental results to prove the effectiveness of the scheme