4 phase 8 / 6 Switched Reluctance Motor for low voltage fan drive

Abstract

The present invention aims to propose the structure or design of three types of SRMs suitable for the requirements of cooling fan devices, namely 6 / 4, 12 / 8, and 8 / 6 SRMs, and to propose an optimal motor design among them. To this end, the present invention compared these motors by inductance, torque, and efficiency to evaluate their performance. In this invention, the dimensions of the SRM were predicted by a predetermined constraint equation, and the parameters were obtained by selecting predetermined values ​​based on the performance through an iterative process in a steady state. In addition, the present invention analyzed the influence of motor design parameters on motor performance and used finite element analysis (FEA) and transient analysis to characterize design requirements. The present invention is characterized by being a 4-phase 8 / 6 SRM for driving a low-voltage fan used when the requirements for a vehicle cooling fan motor are a rated output of 600W, torque of 1.67Nm, speed of 2800rpm, total weight of 1.7kg, current of 50A, input voltage of 12V, and efficiency of 80%, and satisfying the conditions of a stator diameter of 105mm, a rotor diameter of 61mm, a stack length of 35mm, an air gap of 0.25mm, a number of phases of 4, a stator pole arc of 21°, a rotor pole arc of 23°, an shaft diameter of 10mm, and a slot area of ​​284mm. In the present invention, 6 / 4, 12 / 8, and 8 / 6 SRMs suitable for automotive cooling fan devices were designed and simulations were performed. The simulation and experimental results showed that these three types of motors can meet the requirements of the device, and among them, the 4-phase 8 / 6 SRM, which has 8 poles in the stator and 6 poles in the rotor, has better performance efficiency under the same conditions.

Description

Technology Field

[0001] The present invention relates to a switched reluctance motor for automotive fan drive, and in particular to a 4-phase 8 / 6 SRM (switched reluctance motor) for low-voltage fan drive. Background Technology

[0002] Generally, small cooling fans are driven by DC or single-phase induction motors, which have a limited variable speed range and low efficiency.

[0003] To improve performance and efficiency, brushless DC motors (BDCM) are sometimes adopted, but this presents problems such as increased costs and heat generation. Additionally, for AC motor drives with a wide variable speed range, there is the issue of inevitably having to use expensive inverters.

[0004] Meanwhile, compared to other commonly used motors, the switched reluctance motor (SRM) has many advantages such as a simple and robust structure, low inertia, high fault resistance, high torque generation and acceleration capability, suitability for high-speed operation, a simple driving circuit, and convenient switching control.

[0005] In particular, in the case of SRM rotors, there is no cogging torque because there are no conductors or permanent magnets, making it easy to start.

[0006] For this reason, there has been a growing trend recently to use these switched reluctance motors (SRMs) in home appliances, air conditioners, and car fans [1]-[8]. Prior art literature

[0007] [1] D. H. Lee, H. K. M. Khoi, J. W. Ahn, "Design and Analysis of High Speed 4 / 2 SRMs for an air-blower", IEEE International Symposium Industrial Electronics, pp.1242-1246, July 2010.[2] R. Krishnan : Switched Reluctance Motor Drives. CRC Press LLC, Boca Raton, Florida, 2001.[3] A. Labak, N.C. Kar, : "A novel five-phase pancake shaped switched reluctance motor for hybrid electric vehicles," Vehicle Power and Propulsion Conference, 2009. VPPC '09. IEEE , vol., no., pp.494-499, 7-10 Sept. 2009.[4] D. H. Lee,T. H. Pham and J. W. Ahn, "Design and operation characteristics of four-two pole high-speed SRM for torque ripple reduction,"IEEE Trans. Ind. Electron., vol. 60, no. 9, pp. 3637-3643, Sep. 2013.[5] K. Bie.kowski, J. Szczypior, B. Bucki, A. Biernat, A. Rogalski : Influence of Geometrical Parameters of Switched Reluctance Motor on Electromagnetic Torque. Proceedings of XVI International Conference of Electrical Machines, Krakow, 5-8 September 2004.[6] M.Tanujaya, Dong-Hee Lee, Jin-Woo Ahn, 밆esign a Novel Switched Reluctance Motor for Neighborhoods Electric Vehicle", ECCE-Asia, June 2011.[7] Jin-Woo Ahn, Huynh Khac Minh Khoi, Dong-Hee Lee, "Design and analysis of high speed 4 / 2 SRMs for an air-blower", 2010 IEEE International Symposium on, Industrial Electronics (ISIE), vol., no., pp.1242-1246, 4-7 July 2010.[8] Tanujaya, M, D. H. Lee, J. W. Ahn, "Characteristic analysis of a Novel 6 / 5 c-core type three-phase Switched Reluctance Motor" IEEE International Conference of Electrical Machines and System, pp. 1-6, Aug 2011.[9] T. Uematsu, R. S. Wallace "Design of a 100Kw Switched Reluctance Motor for Electric Vehicle" IEEE Transactions on Industrial Electronics, vol. 49, no 1, pp 160-170, Feb 2002.

[10] T.J.E. Miller, "Optimal Design of Switched Reluctance Motors" IEEE Transactions on Industrial Electronics, vol. 49, no 1, pp 160-170, Feb 2002.

[11] K.N. Srinivas and R.Arumugam, “Finite element analysis combined circuit simulation of dynamic performance of switched reluctance motors,” Electric Power Components and Systems, Vol. 30, 2002, pp1033-1045.GO Young, "Synthetic structure of industrial plastics," in Plastics, 2nd ed., vol.3, J. Peters, Ed.NewYork:McGraw-Hill,1965,pp.15-64. The problem to be solved

[0008] The present invention aims to propose the structure or design of three types of SRMs suitable for the requirements of cooling fan devices, namely 6 / 4, 12 / 8, and 8 / 6 SRMs, and to propose an optimal motor design among them.

[0009] To this end, the present invention compared these motors by inductance, torque, and efficiency to evaluate their performance.

[0010] In the present invention, the dimensions of the SRM were predicted by a predetermined constraint equation, and the parameters were obtained by selecting predetermined values ​​based on performance through a steady-state iterative process.[9]-

[11]

[0011] In addition, the present invention analyzed the influence of motor design parameters on motor performance and used finite element analysis (FEA) and transient analysis to characterize design requirements.

[0012] Additionally, specific experiments were performed to measure the inductance, torque, and efficiency of the motors proposed in this invention. means of solving the problem

[0013] The present invention is a 4-phase 8 / 6 SRM (switched reluctance motor) for driving a low-voltage fan used when the requirements for a vehicle cooling fan motor are a rated output of 600W, torque of 1.67Nm, speed of 2800rpm, total weight of 1.7kg, current of 50A, input voltage of 12V, and efficiency of 80%, characterized by satisfying the conditions of a stator diameter of 105mm, a rotor diameter of 61mm, a stack length of 35mm, an air gap of 0.25mm, a number of phases of 4, a stator pole arc of 21°, a rotor pole arc of 23°, an shaft diameter of 10mm, and a slot area of ​​284mm. Effects of the invention

[0014] In the present invention, 6 / 4, 12 / 8, and 8 / 6 SRMs suitable for automotive cooling fan devices were designed and simulations were performed. The simulation and experimental results showed that these three types of motors can meet the requirements of the device, and among them, the 4-phase 8 / 6 SRM, which has 8 poles in the stator and 6 poles in the rotor, has better performance efficiency under the same conditions. Brief explanation of the drawing

[0015] Figures 1a to 1f show the flux linkage and flux density of three types of motors proposed in the present invention. Figures 2a, 2b, 3a, 3b and 4a, 4b are simulation and experimental profiles of three types of motor inductances. Fig. 5a is the torque profile of a 6 / 4 SRM, Fig. 5b is the torque profile of a 12 / 8 SRM, and Fig. 5c is the torque profile of an 8 / 6 SRM. Figures 6a to 6c are dynamic model graphs of 6 / 4 SRM, 12 / 8 SRM, and 8 / 6 SRM, respectively. Figures 7a to 7c are experimental waveforms of 6 / 4, 12 / 8, and 8 / 6 SRMs under rated speed conditions. Figures 8a to 8c are speed-torque curve graphs of three types of motors (6 / 4 SRM, 12 / 8 SRM, 8 / 6 SRM) proposed in the present invention. Specific details for implementing the invention

[0016] Hereinafter, the SRM for driving a low-voltage fan proposed in the present invention will be described with reference to drawings and the like.

[0017] In the present invention, SRM is an abbreviation for Switched Reluctance Motor, and refers to a switched reluctance motor.

[0018] As is known, SRM has advantages suitable for cooling fan devices.

[0019] The SRM of the present invention is also designed for such cooling fans, and an example of the requirements and dimensions of a cooling fan device for automobiles is as shown in Table 1 (Requirements for an automobile cooling fan motor) below.

[0020] parameters value unit Rated output 600 W torque 1.67 Nm speed 2800 RPM Total weight 1.7 Kg electric current 50 A Input voltage 12 V efficiency 80 %

[0021] SRMs can be designed with various phases, such as 2-phase, 3-phase, and 4-phase, depending on the combination of the number of stator and rotor poles. Pole selection is one of the most important processes at the start of the design, as the phase and number of poles are closely related to motor performance, such as losses, efficiency, torque ripple, and noise.

[0023] In the present invention, three types of SRM (6 / 4, 8 / 6, 12 / 8) are designed and their performance is to be compared and evaluated.

[0025] The output equation relates to the bore diameter, length, speed, and magnetic and electrical loads for mechanical output.

[0026] Generally, the design of a conventional motor starts from the following output equation.

[0027] [Equation 1]

[0028]

[0030] Here, is efficiency, and is the duty cycle defined in Equation 2, and class is the respective coefficient calculated in Equation 3 and Equation 4.

[0031] is the magnetic flux density of the fixed pole at the alignment position, and is a specific electrical load defined in Equation 5. It is just for sightseeing, is the axial length of the fixed pole, and is the rotor speed (unit, revolutions per minute (rpm)).

[0032] [Equation 2]

[0033]

[0034] is the current conduction angle for each rising inductance profile, and is the number of stator phases, and is the number of poles of the rotor.

[0035] [Equation 3]

[0036]

[0038] [Equation 4]

[0039]

[0040] Here, represents the aligned saturation inductance per phase represents an aligned but unsaturated inductance per phase. is the unaligned inductance per phase.

[0041] [Equation 5]

[0042]

[0043] Here, is the number of turns per phase, and is the stator current, is the number of phases challenged simultaneously.

[0045] In order to enable the motor to start automatically, stator pole arc and rotor magnetic arc It must satisfy the conditions of the following Equations 6 and 7.

[0047] *[Equation 6]

[0048]

[0049] [Equation 7]

[0050]

[0051] In terms of torque, the smaller the gap, the better the torque. However, the gap can vary depending on the level of machining. The typical gap range is about 0.25 to 0.3 mm.

[0052] Stator back iron thickness It is determined by the maximum magnetic flux density within the stator, and minimizing vibration to reduce acoustic noise can also be determined by other additional factors.

[0053] The magnetic flux density in the stator back iron is approximately half the magnetic flux density in the stator pole, but it may be slightly larger.

[0054] The rotor pole arc is selected to accommodate the magnetic flux density of the pole.

[0055] If, the width of the play If the relationship between and extreme arcs is equal to the following Equation 8, is at least 0.5 It has the value of.

[0056] [Equation 8]

[0057]

[0059] Considering mechanical robustness and the minimization of vibration, it may be desirable to satisfy conditions such as those in Equation 9 below.

[0060] [Equation 9]

[0061]

[0063] Rotor back iron thickness It can be related to structural integrity and operating flux density.

[0064] The range of selected values ​​should be chosen so that the inter-pole air gap can be larger to increase the ratio between aligned and unaligned inductances, but at the same time, it may be desirable to make the rotor poles shorter to minimize rotor vibration.

[0065] Considering these points, and taking into account the rotor pole width, the rotor back iron thickness It may be desirable to satisfy the following Equation 10.

[0066] [Equation 10]

[0067]

[0068] Depending on the requirements or constraint equations of a specific device, the main design parameters of the 6 / 4, 8 / 6, and 12 / 8 SRMs may be as shown in Table 2.

[0069] Type 6 / 4 12 / 8 8 / 6 unit Stator diameter 105 105 105 mm Rotor diameter 62 62 61 mm Stack length 35 35 35 mm air gap 0.25 0.25 0.25 mm Number of phases 3 3 4 Statorium arc 30 14 21 ° Rotor pole arc 32 16 23 ° Shaft diameter 10 10 10 mm slot area 293 210 284 mm

[0070] As can be seen in Table 2, the stator diameter, stack length, air gap, and shaft diameter of the three types of motors above are identical, which is very advantageous for comparing the performance of these motors.

[0071] III. Characteristic Analysis

[0072] A. Static Analysis

[0073] Generally, the finite element analysis method (FEA) is used for steady-state performance measurement, and in this invention, static analysis was performed on 3-phase 6 / 4, 12 / 8 SRMs and 4-phase 8 / 6 SRMs.

[0074] SRMs are generally designed to operate in the saturation region.

[0075] Figures 1a to 1f show the flux linkage and flux density of three types of motors proposed in the present invention. Figures 1a and 1b are 3-phase 6 / 4 SRAM, Figures 1c and 1d are 3-phase 12 / 8 SRM, and Figures 1e and 1f are 4-phase 8 / 6 SRM.

[0076] As can be seen from the results of Figures 1a to 1f, the magnetic flux flow passes through the excited pole when the phase current is excited, and does not pass through the other unexcited pole.

[0077] Inductance and torque are two important characteristics of a motor.

[0078] The SRM is characterized by an inductance that varies with rotor position and current.

[0079] The inductance value also affects current, torque, and efficiency.

[0080] Figures 2a, 2b, 3a, 3b and 4a, 4b are simulation and experimental profiles of three types of motor inductances, and the results are summarized in Table 3 (inductances of three types of motors).

[0082] 6 / 4 12 / 8 8 / 6 Min. Max. Min. Max. Min. Max. Simulation [mH] 0.0278 0.200 0.0246 0.1149 0.0527 0.2514 Experiment [mH] 0.0321 0.205 0.0303 0.1034 0.0577 0.2322

[0083] As can be seen in Table 3, for certain motors, the simulation results were larger than the experimental results. In SRM, torque is generated by the natural tendency of the stator pole to attract the adjacent rotor pole.

[0084] When the phase is excited before the rotor poles are aligned with the stator poles, the rotor feels torque in the direction of rotation that matches the motor's operation.

[0085] Torque is a function of current and rotor position.

[0086] The torque profiles of the motors proposed in the present invention are shown in FIGS. 5a to 5c.

[0087] Fig. 5a is the torque profile of a 6 / 4 SRM, Fig. 5b is the torque profile of a 12 / 8 SRM, and Fig. 5c is the torque profile of an 8 / 6 SRM.

[0088] Figures 6a to 6c are dynamic model graphs of 6 / 4 SRM, 12 / 8 SRM, and 8 / 6 SRM, respectively.

[0089] Table 4 compares the performance of the three types of motors proposed in the present invention, and the 6 / 4, 12 / 8, and 8 / 6 type SRMs are each designed to have average torques of 1.74 Nm, 1.72 Nm, and 1.74 Nm, respectively.

[0090] Type 6 / 4 12 / 8 8 / 6 unit External power 512.52 505.49 507.94 W Average torque 1.74 1.72 1.74 Nm speed 2800 2800 2800 rpm electric current 50 50 50 A Input voltage 12 12 12 V efficiency 88.5 85.3 85.3 %

[0091] IV. Experimental Results A. Driving Performance

[0092] The experimental waveforms of the 6 / 4, 12 / 8 and 8 / 6 SRMs under rated speed conditions (2800 rpm) are as shown in Figures 7a to 7c.

[0093] The load torque was maintained at a rated speed of 1.7 Nmh.

[0095] Figures 8a to 8c are speed-torque curve graphs of three types of motors (6 / 4 SRM, 12 / 8 SRM, 8 / 6 SRM) proposed in the present invention. From Figures 8a to 8c, the relationship between the efficiency and speed of the motor can be seen.

[0096] The results of Figures 8a to 8c are summarized in Table 5 below. As can be seen from Table 5, the 8 / 6 SRM has the maximum efficiency under the same conditions.

[0097] Type parameters 6 / 4 12 / 8 8 / 6 unit simulation 88.5 85.3 85.3 % experiment 81.0 81.4 85.2 %

[0098] Accordingly, the present invention is a 4-phase 8 / 6 SRM (switched reluctance motor) for driving a low-voltage fan used when the requirements for a vehicle cooling fan motor are a rated output of 600W, torque of 1.67Nm, speed of 2800rpm, total weight of 1.7kg, current of 50A, input voltage of 12V, and efficiency of 80%, and satisfies the conditions of a stator diameter of 105mm, a rotor diameter of 61mm, a stack length of 35mm, an air gap of 0.25mm, a number of phases of 4, a stator pole arc of 21°, a rotor pole arc of 23°, an shaft diameter of 10mm, and a slot area of ​​284mm. In addition, the stator has 8 stator poles and the rotor has 6 rotor poles, and the air gap is formed between the stator and the rotor. As described above, in the present invention, 6 / 4, 12 / 8, and 8 / 6 SRMs suitable for automotive cooling fan devices were designed and simulations were performed. The simulation and experimental results showed that these three types of motors can meet the requirements of the device, and among them, the 4-phase 8 / 6 SRM, which has 8 stator poles and 6 rotor poles, has better performance efficiency under the same conditions.

Claims

Claim 1 A 4-phase 8 / 6 SRM (switched reluctance motor) for low-voltage fan driving used when the requirements of a vehicle cooling fan motor are rated output 600W, torque 1.67Nm, speed 2800rpm, total weight 1.7kg, current 50A, input voltage 12V, and efficiency 80%, satisfying the conditions of a stator diameter of 105mm, a rotor diameter of 61mm, a stack length of 35mm, an air gap of 0.25mm, a number of phases of 4, a stator pole arc of 21°, a rotor pole arc of 23°, an shaft diameter of 10mm, and a slot area of ​​284mm, wherein the stator has 8 stator poles and the rotor has 6 rotor poles, and the air gap is formed between the stator and the rotor.

Images