I would also like to express my gratitude to the staff members of the department for providing all necessary facilities for carrying out this research work. I would like to specially thank all the help given by Ranjeet during my stay in Hyderabad.
Abstract
The analysis models developed in the third part of the thesis have been validated with the experimental results in testing the DRM section. The prototype of DRM presented in the thesis was not optimized and the power density and efficiency of the engine were not focused.
List of Tables
121 6.17 Comparison of experimental and SSM torque results while loading the outer rotor at 8 Hz.121 6.18 Comparison of experimental and SSM torque results while loading both rotors at 10.
List of Acronyms
List of Symbols
Introduction
Contents
- Introduction
- Expected characteristics of motor drives for EVs
- Motors used in EVs
- Brushed DC motor
- Permanent magnet brushless DC (PMBLDC) motor
- Induction motor (IM)
- Motivation
- Switched reluctance motor (SRM)
- Aim of the thesis
- Thesis contribution and organization
All the above advantages as well as disadvantages are quite critical for EV application. The DRM prototype presented in the thesis is not optimized and power density and motor efficiency are not focused.
Dual rotor motor: Operating principle and possible configurations
- Introduction
- Possible Configurations of DRM based on conventional motor types
- Possible Configurations of DRM based on positions of motor parts
- Working principle of DRM
- FEA analysis of models M1-M4
- Summary and Conclusion
Also, the distribution of flux lines is also non-uniform along the circumference of the car. Whereas, in M1, all the flux lines connect the outer as well as the inner rotor and the flux is also distributed uniformly along the circumference of the motor.
2-D Analytical Subdomain Model for DRM
Introduction
The DRM configuration considered for analytical model is the one finalized in the previous chapter with squirrel cage (SC) and PM rotors. To avoid deviation from the main objectives of the work and to keep the mathematical model simpler, the assumptions made are given in the next section.
Motor Geometry and Assumptions
The torque in the motor is calculated from the air gap magnetic field in both air gaps in the motor. The development of an analytical model based on the engine geometry and assumptions discussed here is described in the next section.
Analytical model
- Equivalent current sheet distribution
- Magnetization of Permanent Magnet
- Inner rotor reference frame
- Current Excitation in inner rotor reference frame
- PM Excitation in cage rotor reference frame
- Magnetic Field Calculation .1 Governing Equations.1Governing Equations
- Potential Functions
- Boundary Conditions
- Inner rotor bar current calculation
The winding factor Kwν depends on the arrangement of the coils in the stator slots and is given by (3.4). Continuity conditions between the qth rotor bar and the internal air gap result in the following boundary conditions:. The resulting rotating magnetic field due to excitation of the stator and PM causes an induced current in the conducting bars of the inner rotor.
Where, r is the radius of the circle taken as the path of integration in the air gap and ∗ is the complex conjugate notation.
Results and Discussion
Thus, the torque calculated in the outer air gap using (3.62) also includes the torque produced by the inner rotor and was thus represented by the total torque TemT (total torque, i.e. the sum of the inner and outer rotors). To find the outer rotor torque (Temor) separately, the inner rotor torque (Temir) is subtracted from the total torque (TemT) as given in (3.63). The operation of the DRM depends on the starting angle of the outer rotor (δ) and the inner rotor speed (NIR).
Radius of integration path in inner air gap (Rir) 61 mm Radius of integration path in outer air gap (Ror) 66 mm.
Summary and Conclusion
Steady State Model for DRM
Introduction
A steady-state model (SSM) of any motor helps to understand its operation, steady-state performance characteristics, and an electrical representation of the magnetic field interaction between motor parts [39]. The novelty of this work lies in the development of a steady-state model for a DRM that includes an electrical equivalent circuit (EEC) and performance equations. The EEC is developed by deriving the voltage equation and the engine performance is evaluated from the derived torque equation.
To validate the results of the developed DRM model, a comparison is made with those obtained from FEA.
Development of Steady State Model of DRM
- Development of Electrical Equivalent Circuit for DRM
- Derivation of Torque Equation for DRM
- Verification of the Developed Torque Expression
While the mutual inductions between stator and inner rotor phases are a function of the inner rotor position (θst im). The current and field (ϕim) produced by it lag Erby behind the power factor angle (β). Step V4: In (4.3) also appear the inner rotor currents that must be determined in terms of the stator currents given in (4.10).
Similarly, the flux linkage equations for the other phases of the stator and the inner rotor can also be formulated.
FEA Validation
- Determination of parameters of EEC
The torque and maximum current change in the DRM versus the initial displacement angle of the outer rotor δst pm are as shown in Fig. The second set of validations was performed by varying the slip (s) of the inner rotor for specific δst pm. Additional results showing the performance of DRM over the 0◦−360◦range of δst pm for different values of slip (s) are shown in Figs.
After validating the developed EEC with FEA, it can be further used to analyze the DRM torque characteristic for other values of pm and s.
Conclusion
It can be deduced that the motor will produce minimum torque at s = 0, and this will only be torque due to the outer rotor. The input stator current obtained from the EEG closely matches the values obtained from FEA to validate the EEG. Likewise, the torque determined from the torque expression developed also closely matches that of FEA results, to validate the work done.
The method is also presented in a simple and systematic way and can be easily implemented for any new type of engine with different configuration.
Design and prototyping of DRM
Introduction
Design of DRM
- Electrical design of DRM
- Design of stator
- Design of outer rotor
- Design of inner rotor
- FEA modeling of DRM
- Mechanical design of DRM
Since the internal rotor of the DRM is a PM rotor, the DRM can be considered an internal permanent magnet (IPM) motor. Standard design principles [51] were followed to determine the number of rods and the rod shape. Therefore, unlike most IMs, the number of bars for the rotor cage was chosen less than the number of stator slots, i.e.
Thus, the mechanical design of the engine was made in such a way that the power of both rotors is available independently.
Manufacturing of DRM
shows the pictures of the lamination cut from the sheet of the material 50C350AP with laser cutting machine.
Installation of Hall sensors in DRM
Summary and Conclusion
Testing of DRM
Introduction
For a better understanding of the arrangement, the setup seen from the front and from above is shown in fig. DC generators with resistors connected to their armature terminals have been used as loads for both rotors. The torque for both rotors is measured from the output power of the DC generators divided by mechanical speed in rad/sec.
The output power of the DC generator is obtained as the sum of power consumed by load resistance (RL) as well as copper losses in generator windings as shown in (6.1).
Control strategy for DRM
The inner rotor is directly connected to the load as in the case of any conventional motor, while the outer rotor is connected to the load through a gear arrangement as shown in the figures. The simplest and widely used technique of 120◦ commutation control of the stator phases based on the output of Hall sensors is used for DRM. If the motor phases are properly switched in synchronism with the rotor position, then the outer rotor rotates smoothly and the inner rotor also rotates to catch up with the rotating field created by the outer rotor.
The switching signals for the six switches in the inverter are produced from the Hall sensor output of DRM using the dSPACE 1103 system, as shown in Fig.
DRM Q1 Q3 Q5
- Testing of DRM
- Sine Pulse Width Modulation (SPWM) technique
- Open circuit tests
- Inner rotor loading tests
- Outer rotor loading tests
- Both rotors load test
- Validation with FEA
- Validation with SSM
- Comparison with conventional SPM motor
- Summary and Conclusion
The inner rotor is coupled to a DC generator, while the torque gear is removed from the outer rotor and kept free. Initially, the outer rotor is loaded with a fixed load and the load on the inner rotor is increased step by step. It can be observed that the waveforms are similar to the waveforms during the outer rotor load test.
Fig. 6.18 and 6.19 present a comparison of the torque obtained from experiment and FEA for inner rotor load tests at 20 and 25 Hz, respectively.
Conclusion and Future Work
Conclusion
Therefore, it is desirable to have a high power density and high efficiency motor used for the EV powertrain. This thesis discusses the different types of motors used for electric vehicle applications and their limitations.
Summary of Contributions
Future work
The present DRM experimentation was carried out using the 120° commutation technique, and it was found that the outer rotor is the main drive rotor, so PMCLDC control should be used. In the current DRM configuration, rectangular magnets were used in the outer rotor.
Development of Boundary Conditions and Final Equations
Equations (8.13) and (8.14) are written using (3.49), where at r=Rr this continuity equation becomes the Fourier expansion of Aia(r, θ) in a series in the interval h.
Additional details for steady state model of DRM
So the cage rotor must be transformed into an equivalent three-phase winding to find the turns ratio. The procedure for transforming the cage rotor into an equivalent three-phase winding is described below. This Nb phase system is transformed into a two-phase system in the same way as a three-phase system is transformed into a two-phase system.
From (9.8) it is thus concluded that if a burrotor with Nb bars is converted into a 2-phase winding, each winding will have N2b turns carrying the same current as that of a bar.
Bibliography
Wang, “Electromagnetic performance analysis of double-rotor stator permanent magnet motor for hybrid electric vehicles,” IEEE Trans. Chan, “The study of the operation modes and control strategies of an advanced automotive electromechanical inverter,” IEEE Trans. Wen, “Multioperational modes and control strategies of dual mechanical gate machines for hybrid electric vehicles,” IEEE Trans.
Jahns, “Torque production in permanent magnet synchronous motor drives with square current excitation,” IEEE Trans.
List of Publications
Amit Kumar Singh, Ankit Dalal, Rokesh Roy and Praveen Kumar, "Improved Dynamic Model of Induction Motor Including Saturation Effects". IEEE PEDES, IIT Bombay, Mumbai, India, December 16 - 19 Amit Kumar Singh, Ankit Dalal and Praveen Kumar, "Analysis of Induction Motor for Electric Vehicle Application Based on Drive Cycle Analysis." IEEE PEDES, IIT Bombay, Mumbai, India, December 16 - 19 Ankit Dalal, Mohammed Nasir Ansari, Praveen Kumar, "Analytical Model of Induction Motor for Performance Calculation", IEEE COMPUMAG Int.
Ankit Dalal, Amit Kumar Singh, Praveen Kumar, "Saturation Effect on Equivalent Circuit Analysis of Induction Motor in Practical Scenario", X. IEEE INDICON 2013, I.I.T.
