Variable speed multiphase induction machine using pole phase modulation principle

Fuel consumption of the engine becomes tolerably economical when it runs under operating conditions of low speed and high torque rather than of high speed and low torque. Therefore, if an automobile engine is operated by consolidated control with continuously variable transmission (CVT), the minimum fuel consumption is achieved, satisfying the driver's demanded vehicle speed. The effect of this consolidated control on fuel economy depends on several factors such as specification of the object automobile, range of the transmission gear ratio (Rm) of equipped CVT, and the driving mode of the automobile itself. In this report, Rm range and driving mode were focused on and their influence on fuel economy was investigated by simulation studies.

Fuel consumption of the engine becomes sufficiently economical when it runs under operating conditions of low speed and high torque rather than of high speed and low torque. However, it is difficult for automobiles to run under such economical conditions because acceleration is frequently required. Therefore, if an automobile engine is operated by consolidated control with continuously variable transmission (CVT), the minimum fuel consumption will be achieved, satisfying the driver's demand for a particular vehicle speed. The advantage of this consolidated control for fuel economy depends on several factors, such as specifications of the automobile, the performance of controllers, the driving mode of the automobile and the performance of the control actuators. In this report, the required CVT's operating speed which involves the performance of the actuators was investigated by simulation studies as well as theoretical analysis.

Pole-phase modulation is a method of adjusting the pole-phase ratio of an electrical machine. Based on this method, an induction machine has been developed to operate in either a 12-pole-3-phase or a 4-pole-9-phase configuration. For applications requiring high torque, the 12-pole-3-phase configuration is used, whereas, 4-pole-9-phase configuration is used for applications requiring high speeds. Currently, switching between configurations requires the machine to be de-energized. For applications such as electric vehicle drives, induction machines are required to have both high starting torque and an extended speed range. There, unlike in a starter/alternator, continuous torque production is necessary. Continuous pole-phase modulation allows an induction machine to change configurations without the need to de-energize its windings. The result is an equivalent induction machine with extended speed-torque capability. A smooth transition (minimum torque ripple) and optimal torque production are desired during pole-changing. A method is presented to accomplish both in a 12/4 pole induction machine. The induction machine is modelled as two independent machines acting on the same load. The two machines operate simultaneously and produce independent torques. Pole changing is accomplished by increasing the torque output of one machine while decreasing the torque output of the other machine.

In recent years, low speed and high torque direct drive motor is increasingly used in many application for industrial drive for the improved performance, especially for replacing the motor with structure of reducer which possess some shortcomings, such as complex structure, big volume and low efficiency of transmission. In this paper, we designed a 32poles/30slots fractional slot direct drove motor with surface mounted permanent magnet structure for low speed and high torque. We put the UDLR (up, down, left, right) four layers winding designing method into use to decrease the torque ripple. With two permanent magnet materials combined in the rotor, we can decrease harmonic components in electromotive force (later shows EMF) and attain more perfect sinusoidal waveform in EMF.

The six‐phase direct‐drive permanent magnet synchronous motor (DDPMSM) has a good prospect in electric vehicles, ship propulsion, aerospace and other fields due to the advantages of low voltage, high power, low speed and high torque. In this study, a six‐phase DDPMSM is proposed with 60° phase‐belt toroidal winding configuration (60°‐TW). Different from traditional overlapping windings, each coil of 60°‐TW is wound onto the stator yoke in the same direction. The topology of the proposed motor is introduced, and its operation principle is analysed by describing the variation of the magnetic field produced by the six‐phase 60°‐TW versus time. Meanwhile, based on the same power grade and effective volume, the six‐phase PMSM and dual‐three phase PMSM with different winding arrangements are designed. The magnetic field distribution, back‐EMF, cogging torque, torque and loss characteristics are explored in detail. The results show that the proposed six‐phase DDPMSM with 60°‐TW has the characteristics of low speed and high torque in comparison to the traditional six‐phase PMSM and dual‐three phase PMSM, which is expected for direct‐drive systems.

Pole-phase modulation can provide performance benefits in highly dynamic applications through the electronic control of induction machine pole count. An applicable dynamic model is developed, and verified using finite element analysis. The proposed model can describe machines with an arbitrary number of electrical inputs and pole count configurations. The available degrees of freedom in polyphase vector space decomposition are used to develop decoupled energy conversion subspaces for each available pole count, allowing conventional control techniques to be directly applied. Simulation results for a smooth 2-pole/6-pole transition using field-oriented control techniques are provided.

In the recent days, for the traction and electric vehicle (EV) applications, multiphase machines with pole phase modulation (PPM) technique have been proposed. The smoother operation during pole changeovers as well as steady‐state operations is a significant constraint while adopting the PPM‐based multiphase induction motor (PPMIM) drives for EV and traction applications. So, in this paper, the PPMIM dynamic model and associated vector control are proposed for attaining a smoother operation of the machine. The machine modelling equations and transformation matrices are implemented in an arbitrary reference frame by considering the different pole phase combinations. Based on the modelling equations, the indirect field‐oriented control (IFOC) is proposed for PPMIM drives by reflecting the associated changes in parameters for different pole phase modes. In the IFOC, for regulating the d ‐axis and q‐ axis current components, single PI control loops have been implemented for all pole‐phase combinations. The proposed IFOC scheme is robust and applicable for adopting any type of pulse width modulation. The experimental, as well as simulation results, are given to illustrate the potentiality of the proposed dynamic model and IFOC. The PPMIM machine performance during the steady state as well as pole changeovers in different pole phase modes are analyzed and associated. Simulation and experimental results are presented.

This paper introduces an improved magnetic-geared permanent magnet (MGPM) in-wheel motor with high power density and torque density for electric vehicles (EVs). Due to the integrating of the magnetic gear and omitting of the gear inner rotor, the motor can achieve the low speed direct driving and high speed compact designing requirements with even simple structure. The principle and optimized structure are described. A 750w optimized motor is designed and analyzed by finite element method. The simulation results validate that the MGPM in-wheel motor can be operated at low speed, high efficiency and high torque. It is suitable for direct-driving EVs.

The pole phase modulation (PPM) technique is an effective method to extend speed range and torque capabilities for an integrated starter and hybrid electric vehicles applications. In this paper, the five pole-phase combination types of a multiphase induction motor (IM) with 36 stator slots and 36 stator conductors are presented and compared quantitatively by using the time-stepping finite element method (TS-FEM). The 36 stator conductors of the proposed multiphase IM are fed by a 36 leg inverter and the current phase angle and amplitude of each stator conductor can be controlled independently. This paper focuses on the winding connection, the PPM technique and the performance comparative analysis of each pole-phase combination types of the proposed multiphase IM. The flux distribution, air-gap flux density, output torque, core losses and efficiency of five pole-phase combination types have been investigated.

Double frequency tests are used for evaluating stator windings analyzing the temperature. Likewise, signal injection on induction machines is used on sensorless motor control fields to find out the rotor position. Motor Current Signature Analysis (MCSA) is the most widely used method for identifying faults in Induction Motors. MCSA focuses its efforts on the spectral analysis of stator current. Motor faults such as broken rotor bars, bearing damage and eccentricity of the rotor axis can be detected. However, the method presents some problems at low speed and low torque, mainly due to the proximity between the frequencies to be detected and the small amplitude of the resulting harmonics. This paper proposes to inject an additional voltage into the machine under test at a frequency different from the fundamental one, and then to study the resulting harmonics around the new frequencies appearing due to the composition between injected and main frequencies.

Field excitation flux switching machines (FEFSMs) in which their torque performance produced by interaction between armature and field excitation (FE) coils have been widely designed for various applications. In this regard, three-phase salient rotor FEFSM with overlap windings is considered the most suitable candidate for high speed applications because of their advantages of flux controllability, and robust due to single piece of rotor structure. However, the overlap windings cause a high copper loss, hence efficiency of the motor becomes low and higher stack length. Besides, the salient rotor structure is found to produce low torque performance due to the longer flux path in stator and rotor yielding weak flux linkage. In this paper, a new single-phase FEFSM using non-overlap windings between armature coils and FE coils is proposed. Both non-overlap windings FEFSMs with salient and segmental rotors have been designed using JMAG Designer version 15 and the investigation process is conducted via 2D finite element analysis. The proposed motor performances verification has been done by comparing the results of flux linkage, flux line and distribution, flux strengthening, various torque capability, and torque-power versus speed characteristics. As a conclusion, single-phase non-overlap windings FEFSM using segmental rotor with power, torque and speed capabilities of 277.5 W, 0.91 Nm and 2,899 rpm, respectively considered as the best candidate for low torque high speed applications.

BackgroundThe flexor carpi ulnaris (FCU) and flexor digitorum superficialis (FDS) are thought to provide dynamic stability to the medial elbow, with a lesser contribution from the pronator teres (PT).Hypothesis/PurposeThe purpose of this study was to determine if baseball pitchers with higher valgus elbow torque experience greater FCU and FDS strength loss.Study DesignControlled Laboratory StudyMethodsA pilot study was performed to determine if middle and ring finger flexion strength tests preferentially activated the FCU and FDS versus the PT (10 men age 36±12 yr). EMG amplitudes, expressed as percent of maximal voluntary contraction (MVC) were compared between tests and muscles. In a field study of college baseball pitchers, middle finger, ring finger and grip strength were tested prior to, immediately after, and one day after 14 pitching performances in 10 pitchers (21±2 yr). Elbow valgus torque was measured from an inertial measurement unit, housed in a compression sleeve and pitchers were categorized as having high or low valgus torque.ResultsFor the pilot study EMG activations were 74% FDS, 66% FCU and 35% PT for the middle finger test (muscle effect p=0.032) and 93% FCU, 61% FDS and 23% PT for the ring finger test (muscle effect p=0.005). In the field study, pitchers with high valgus torque showed marked post-game middle finger fatigue (88% of baseline) and incomplete recovery the following day (95%), while pitchers with low valgus torque showed no strength loss (107% post game, 106% a day later; group x time p=0.022). Results were similar for ring finger strength (high torque: 94% post game 96% a day later; low torque: 114% post game 107% a day later; group x time p=0.048). By contrast, grip strength was not different between pitchers with high versus low valgus torque (p=0.143).ConclusionHigh medial elbow stress during pitching fatigues the dynamic stabilizers of the medial elbow.Level of EvidenceLevel 3

This paper presents a position sensorless control system based on adaptive observer for low speed and high torque gearless drive system. By studying the theory of adaptive control system, an adaptive speed observer based on neural network is introduced in this system. The experimental results demonstrate that the proposed vector control scheme is valid, and the dynamic and static performances are quite well. Furthermore, the propose strategy has stronge robustness.

The electrification of agricultural vehicles is often discussed. Several prototypes, which use electric machines as a traction drive, are known. However, design of an electric motor is a particular challenge because of the special characteristics of the drive cycle of the agricultural tractor. High torque at low speed and low torque at high speed are required. This results in a wide speed range, which represents a particular challenge for the machine design. This paper describes the possibilities to realize the wide speed range and its influence on the design of electric machines.

Due to the need for developing technology and comfort today, the use of electric motors increases in different fields such as pumps, household appliances, fans, aerospace and mixers. This affects energy consumption and production costs, and ultimately triggered the development of higher performance motors. Because of the multi-parameter designs and nonlinear structure of electric motor, it has become very important the use of multi-objective optimization algorithms in design studies on electric motors. At the same time, real-time simulations are provided by using finite element analysis programs to reduce test costs. This study purposes analysis and multi-objective design optimization of a direct drive permanent magnet synchronous motor with external rotor for low speed and high torque mixer applications. So, the third-generation algorithm NSGAIII was used and compared with the second-generation algorithm NSGAII. To examine both initial design result and optimization results Ansys/Maxwell program was used. According to the initial result, optimized motor geometries provided an efficiency increase of about 3.54% and a cost reduction of about 17%. In addition, the search strategies of both algorithms were compared on motor design parameters.