Effect of direct current motor parameters in the development of magnetic

Cumhuriyet Üniversitesi Fen Fakültesi Cumhuriyet University Faculty of Science Fen Bilimleri Dergisi (CFD), Cilt:36, No: 3 Özel Sayı (2015) Science Journal (CSJ), Vol. 36, No: 3 Special Issue (2015) ISSN: 1300-1949 ISSN: 1300-1949   Effect of direct current motor parameters in the development of magnetic Mohammad reza SOHEILI1,*, Mohammad REZAIE2, Ali VAKILIAN3 Received: 01.02.2015; Accepted: 05.05.2015 ______________________________________________________________________________________________ Abstract. Parameters affecting dc motor performance including number of poles, magnet gap at the middle of polar shoe and magnet gap in angels of polar shoe should be selected and improved so that motor performance and efficiency is increased significantly. In this article one dc motor was designed in different conditions and by the numerical analysis and then was analyzed electromagnetically in the transit state by the maxwell software. Obtained results characterized that by determining improved amount of affective parameters in dc motor performance, energy losses are decreased and the highest power and electromagnetic moment is utilized. Efficiency of motor is increased and also motor reaches to the stable state in the less time period. Keywords: direct current motor, the number of poles, air gap, efficiency 1. INTRODUCTION Dc motors are composed of two following main parts: a) The static part named inducer (stator) at creates the magnetic flux that are placed on this static part of the main poles and auxiliary poles. b) The rotating part named armature with that changes the electric energy to the mechanical energy in motors. There is aerial space between the static and rotating part. Dc motors always have had suitable and good position in the industry due to control of the exact speed and with the extensive range and also having high moment [1]. So these motors are very used in marine and military industries. Of these motors' advantages are: superiority of electromagnetic moment of dc motors to compare with ac motors with the variable frequency, control the exact and variable speed. Also benefiting dynamic power supply like battery has affected validity of Dc motors in many industrial and military industries [2]. Important applications of these motors re in sea subsurfaces, floating boats, military tanks, and other applications that need exact control of moment or speed. In this article three DC motor with different characteristics were designed in different conditions and then electromagnetically analyzed by the Maxwell software. 2. CALCULATION OF DC MOTOR BY THE USUAL METHOD Some main equations for designing DC motor by direct stimulation have been presented by the 1-16 relations [3] until [14]. Pe N π 2 × B × × Be × A 60 Pout I= V .η D 0.5 ≤ ≤ 0.7 P.L π ⋅D τ= 2P D2 L = We have in the 1-4 relations: _____________ *Corresponding author. Email address: Special Issue: The Second National Conference on Applied Research in Science and Technology http://dergi.cumhuriyet.edu.tr/cumuscij ©2015 Faculty of Science, Cumhuriyet University (1)   (2) (3) (4)     Effect of direct current motor parameters in the development of magnetic D: is the external diameter of rotor, L: rotor length, Pe: electromagnetic power of motor and B: is the motor flux density that based on the motor function has different range. N: is Revolutions per Minute. Be: induction at air distance, A: electric loading of motor according to ampereconductor /cm, i: nominal current, pout: nominal power, V: nominal voltage, η : efficiency that is about 90%, P: number of pole couple, τ : size of polar step curve. V Ns Ne ± 1 YA = 4 Pθ .Nc.Lsp Ra = 2 2.Scu.(2a ) Nk .tc Dc = Vmo = 2 p (5) (6) (7)       (8) π We have in the 5-7 relations: Vmo: Voltage between the collector blades, Ns: The number of coils series in parallelway each, YA: average step size slots, Ne: Number of rotor slots, Ra: wiring resistance of the armature, Nc: number of rotor conductors, Lsp: During a ring armature wiring in meters, Scu: pure copper cross-section of the groove, 2a: Number of parallel annular current, and the wiring is equal to 2. Dc: Diameter collector, Nk: Number of Blades Collector, tc: Total width of a blade collector and insulated, π : Is equal to 3.1415. Figure 1 shows a simple wave paths current the wiring. Figure 1. Current paths for wiring simple wave [ ( S = 3.ea et − 2 × i )] ⎛ D ⎞ Zc = td + be + (et − tc )⎜ ⎟ ⎝ Dc ⎠ Fa = τ .In A Spa = Jpa (9)   (10)   (11)   (12) The relations (9) to (12) we have: S: useful contact brushes each category three, ea: Length of brushes, et: width brushes, Zc: the width of auxiliary pole, Td: the indentation step, be: track width, Fa: magnetic driving force, in: motor rated current, Spa: cross-section of the wire used for winding excitation, Jpa : The current density at the pole auxiliary winding. S = Ea = k .ϕ.w (13)   T = K .ϕ.Ia (14) 2591     SOHEILI, REZAIE, VAKILIAN   A airgap = ε ≥ (0.6 − 1.5)B Be td Kc = be 2 td − 5ε + be (15)   (16) In equation (13) to (16) we have: Ea: force induced by the two ends of the armature, k: constant machine, T: Induction motor torque, Kc: Carter's coefficient. The equivalent circuit of a direct current motor in Figure 2 is given. Figure 2. Equivalent circuit of a direct current motor with independent excitation Armature orbit includes a voltage source and a resistor Ra is the ideal Ea. The equivalent circuit with an external resistor Rd and right with an internal resistance Rf is equivalent inductance Lf. 2.1. Determine Requirements Dc motors used in the industry usually should satisfy the below requirements: high efficiency, noise decrease, extensive speed range, high reliability, high starting torque and rapid acceleration. Dc motor due to having many of above features, have well development and position in the industry. 2.2. FEM analysis 4- the intended model is a dc motor that has nominal power of 127kw and nominal speed of 222 cycle-minutes. In designing dc motor, most important parameters affecting high efficiency with maximum effectiveness are size of polar number, magnetic gap size and magnetic gap size in corners of main poles shoe. These parameters should be designed to impose motor under the best function condition. To increase efficiency, effectiveness and decrease saturation points, parameters affecting dc motor function are simulated in different amount for this motor by the Finite Element Method. Maxol software has ability to solve electromagnetic equations and dynamic- mechanical equations. So this software has been used to design and analyze noise and disturbances of intended motor in the transit state. Due to symmetry in dc motor, software draw motor as one fourth in order to decrease repeated calculations. 3. SIMULATION MODEL AND RESULTS Parameters affecting the performance of the direct current motor, the number of poles, the air gap and the gap (...truncated)