基于MATLAB的某型轎車輪轂軸承優(yōu)化設(shè)計
基于MATLAB的某型轎車輪轂軸承優(yōu)化設(shè)計,基于,matlab,轎車,輪轂,軸承,優(yōu)化,設(shè)計
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譯文題目： 基于MATLAB的某型轎車
輪轂軸承優(yōu)化設(shè)計
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Design and implementation of multiple-output power supply for electric vehicle
Abstract
The drive circuit of an electric vehicle requires a lot of different isolation voltage. In this paper, a multi-output power supply is designed to supply the drive circuit of an electric vehicle. The power supply system uses a flyback converter to achieve the isolated multi-output sources that contain fourteen sets of output voltage. In order to reduce noise interference, six sets of isolated sources are provided to drive insulated gate bipolar transistor (IGBT). Five sets of isolated sources are supplied for 485 cards, speed detector, and controller circuit of the flyback power supply. Three sets of common ground sources are supplied for status interface, the center processing unit, and the operation amplifier. In addition, a discontinuous conduction mode (DCM) small-signal model, with a peak current mode control, is built, and the feedback controller is designed for stabilizing the desired power supply. Finally, a 20W multiple-output power supply is built to provide the drive sources of the electric vehicle.
Keywords: Electric vehicle, flyback, multiple-output, discontinuous conduction mode
1. Introduction
The electric vehicle consists of electric drive, control system, driving transmission and the mechanical systems. The electric power drive and control system are the center of an electric car and they are also the main difference from the fuel car. The electric power drive and control system are composed of motor drive, power supply and the speed control device of the motor drive. The auxiliary power supply of the driving circuit is inevitable. The voltage of the auxiliary power supply required by driving circuit of the electric vehicle is various and it requests low noise interference. As a result, it is essential to prepare the isolated and individual multiple power supply output. Flyback converter is low-cost and has the developed circuit and the simple structure for the multiple outputs in the auxiliary power supply systems. The circuit itself does not require the isolation but in practice, for the consideration of the power increasing and the safety regulation, the design takes the isolation of the input from the output and the transformer is the common design for this electric isolation and the voltage level adjustment.
2. System Structure
The flyback converter comes out from the Buck-Boost converter. The circuit structure is composed of a power transistor Q , isolated transformer, Tr and the output is diode Do, Capacitor Co and the load. The magnetic element of the flyback converter is made of the high frequency transformer and it acts like a choke. The transformer of high frequency can not only do isolation and adjust the voltage level but also store the magnet because of the air gap existing in the isolated transformer. The basic structure of the flyback converter is shown in the Fig. 1(a). The flyback converter in this design operates in the DCM.
3. Flyback Converter Design
The input voltage of the flyback converter in this paper is DC 360V～420V, the switching frequency is 47kHz and the output power is 20W . Because it is multiple outputs, the secondary output takes the 5% power of the N3、N4、N6、N7、N9～N16 and 10% power of N2、N5 and the 25% power of N8 . The following take the total sum of the output of the each group as the output of a single group ( 5V , 4A , 20W ) [1-2]. The converter operates in the DCM and the turn-on duty cycle () is 0.12.
3.1. The constants design of the Flyback Converter
l Step 1: Calculate the primary inductance（LP）
（1）
l Step 2: Calculate the turn off duty cycle（D2) and the maximum turns（n）to enable the turn-off duty cycle Dr to be 0.52 as shown in Fig. 1(b).
（2）
（3）
l Step 3: Calculate the primary peak value（）of the primary and rms current（).
（4）
（5）
l Step 4: Calculate the secondary rms current（）
（6）
l Step 5: Decide the output capacitor（）
（7）
Because the practical output is multiple outputs, the capacity value can be calculated according to the formula ratio.
3.2. The transformer design of the flyback converter
The following formulas illustrate the calculation and selection of iron core and the diameter of the winding of the transformer and the calculation unit are based on CGS units, magnetic flux is based on Gauss and the current density is calculated based on A/cm.
l Step 6: Select the iron core of the transformer
（8）
l Step 7: calculation of the primary and secondary winding（，）
turn （9） ,take 5 turns (10)
l Step 8: Calculate the skin depth（）and primary and secondary wire size（，）
Skin depth Calculation（）：
（11）
Wire Size Calculation（）：
（12）
(13)
After calculation, the AP of the iron core is =0.288cm, the iron core EI25 of TDK is selected for a single output. Because the secondary output of power supply is multiple outputs, EI25 can not put the total secondary output in it, so the step 6 to step 8 for the selection of the iron core is required to repeat.
l Step 6 (repeat): Select the iron core of the transformer
（14）
l Step 7 (repeat):calculation of the primary and secondary winding(,)
turn (15)
turn (16)
For the other secondary turns, use for calculation.
The following is the result of the secondary turns after calculation: takes 11 turns, takes 11 turns, takes 18 turns, takes 11 turns, takes 8 turns, takes 18 turns, takes 19 turns, takes 11 turns. The actual winding is still based on the inductance.
l Step10: skin depth（）and primary and secondary wire size（、）
（17）
Wire size calculation:
（18）
、、、、～ in the following calculation are calculated with 5% of the total output power and 、 are calculated with the 10% of the total output power and is calculated with the 25% of the total output power and the formula is like (19).
（19）
，，， ，，，
，，.
Considering the output legs and the requirement of the winding to be put in, the iron core EI25 does not meet the requirement. If the calculated wire is too thin to be the winding of the transformer, the final choice would be iron cell EER3928 of FDK.The AP of EER3928 of FDK is AP=1.956cm, and the winding area is=146.There is still space for the window area of the iron cell so the wire size is changed to be.Under the condition that every secondary wire size should not be more than the maximum size of skin depth, the ROBBIN winding area could be best applied. Here takes 0.45， takes 0.2， takes 0.23， takes 0.45， takes 0.2， takes 0.2， takes 0.4 with double winding, takes 0.2， takes 0.23.
The next step is to calculate all the space that all the winding, isolation tape and the isolation layers that would take and the length of each side of iron cores. Because the wire is in the round shape, the gap between the wire and isolation tape can not be put with extra wires just like the Fig. 2(a) shows. The winding space that the wire occupies is calculated with square. Each winding individually takes up the space as below: =14.4，=0.81，=0.44，=0.58，=3.64，=0.44，=0.32，=5.76，=4.56，=0.58Total winding space is the sum of to ,=31.5388.The isolation tape space is .The isolation layer space is .The total space is..The result of the transformer winding and the cross-section of the transformer is in Fig. 2(b).
4. Controller Design
The inverter should have proper feedback control to control the power switch turn-on and turn-off time and sustain the stable output voltage. The PWM control chip adopted in this paper is UC3844.
4.1. Small-Signal Model of Main Circuit in Flyback Converter
The small-signal DCM equivalent circuit of the flyback converter is shown in Fig. 3(a) [3]. Capital letters refer to the DC value and (^) refers to the variation of small signal. In the circuit,
，，，，，，.
4.2. Small-Signal Model of Current Control Mode
In DCM, the inductance current starts from 0 in every cycle and and are not related but and and the slope of are related and these are the results from the DCM current control mode [3-5] and the block Fig. 3(b) shows the peak current control in discontinuous mode. The is the compensator.
The duty cycle to output voltage transfer function is [6]. According to Fig.6, the open loop transfer function is (20)
Where, ，，，，，。
The following values are the results from the calculation of the constants from flyback converter in (20). ，，，，.And the bode plots of small-signal analysis in discontinuous conduction mode is as shown in Fig. 4.
4.3. Compensator Design of Discontinuous Conduction Mode
The zero and pole of the open-loop transfer function of the flyback converter is obtained from the Fig.5 and (20). Fig.1 shows the design of the compensator of Type 2 and Fig.5 shows the bode plots of the compensator Type 2.
The transfer function of the compensator is obtained from the compensator circuit in discontinuous conduction mode shown in Fig. 8
（21）
where, ，，，，
CTR is current transfer ratio of the optocoupler and is the voltage divider gain. The zero(127.877) and pole（1.66610） of the compensator is gained from Fig.4 and the feedback compensator of this design is valued at ，，，，,，，，，，.The bode plot of the compensator is shown in Fig.5.
Fig.6 shows the bode plots of the transfer function after the compensation. The result informs that after the control compensation, the bode plots of the transfer function is in stable status and the gain margin is 74.172dB and phase margin is 90.1°.
5. Simulation and experimental results
Finally, PowerSim software is used to simulate and measure the waveform of each voltage point and current point for the multiple-output power supply.The simulated waveform is shown in Fig.7(a). After confirmation on the simulation and the execution of the practical circuits, the measurement of the waveform of each voltage and current is shown in Fig.7(b).
6. Conclusion
In this paper, the flyback converter is adopted to design a 20W output power supply for the electric vehicle control circuit, the compensator of the discontinuous conduction mode is designed to enable the power supply to have stable multiple output supply for the electric vehicle drive.
Acknowledgement
Thanks to the joint cooperation with Rich Electric for the study project: 120990065, the research effort and the fund is much appreciated.
電動汽車的多路輸出電源的設(shè)計和實現(xiàn)
摘 要：
電動汽車的驅(qū)動電路需要許多不同的隔離電壓。在本篇文章中，設(shè)計了一種由多輸出電源來給電動汽車提供動力的驅(qū)動電路。在該供電系統(tǒng)中，使用了反激式轉(zhuǎn)換器來實現(xiàn)包含十四組輸出電壓的孤立的多輸出來源。為了減少噪聲的干擾，六套獨立源被用來驅(qū)動絕緣柵雙極晶體管（IGBT）。五套獨立源提供了485張卡、速度檢測器和反激式電源的控制電路。三套共同的地面源提供了狀態(tài)界面、中心處理單元和運算放大器。此外，建立一個采用峰值電流模式控制的斷續(xù)導電模式(DCM)小信號模型，并且設(shè)計一個反饋控制器來穩(wěn)定所需的電源。最后，建立一個20W的的多路輸出電源來提供電動汽車所需要的驅(qū)動源。
關(guān)鍵詞：電動汽車，反激式，多輸出，斷續(xù)導電模式
1.引言
電動汽車由電力驅(qū)動系統(tǒng)、控制系統(tǒng)、傳動系統(tǒng)和機械系統(tǒng)四部分組成。電力驅(qū)動系統(tǒng)與控制系統(tǒng)是電動汽車的核心部分，這也是跟燃料汽車的主要區(qū)別所在。電力驅(qū)動系統(tǒng)與控制系統(tǒng)由電機驅(qū)動器、電源和電機驅(qū)動器的速度控制裝置三部分所組成。在驅(qū)動電路中，輔助電源是必不可少的。由于電動汽車中的驅(qū)動電路所需要的輔助電源的電壓是多方面的，與此同時，它要求低噪聲干擾，所以，準備單個的多電源輸出裝置是必不可少的。反激式轉(zhuǎn)換器的成本比較低，并在輔助電源系統(tǒng)的多路輸出中就存在已經(jīng)開發(fā)好電路和簡單的結(jié)構(gòu)裝置。該電路本身并不需要隔離，但是在實踐中，考慮到功率的增加和安全監(jiān)管，從輸出和變壓器到輸入進行隔離的設(shè)計對于電氣隔離和電壓電平調(diào)整來說是比較常見的設(shè)計。
2.系統(tǒng)結(jié)構(gòu)
反激式轉(zhuǎn)換器的設(shè)計起初來自于降壓-升壓轉(zhuǎn)換器。它的電路結(jié)構(gòu)由一個功率晶體管Q、隔離變壓器Tr、輸出二極管Do、電容Co和電阻所組成。反激式轉(zhuǎn)換器的磁性元件是由高頻變壓器制成的，它就如同一個阻流一樣。高頻變壓器不僅可以隔離和調(diào)節(jié)電壓等級，而且由于在隔離變壓器中存在空氣間隙，它還能儲存磁鐵。反激式轉(zhuǎn)換器的基本結(jié)構(gòu)如圖1.(a)所示。在這個設(shè)計中的反激式變換器在DCM模式當中運作。
3.反激式轉(zhuǎn)換器設(shè)計
在本文中，將反激式轉(zhuǎn)換器的輸入電壓值設(shè)定為直流360V-420V，切換頻率的值設(shè)定為47kHz，輸出功率的值設(shè)定為20W。因為它有多個輸出，二次輸出消耗了N3、N4、N6、N7、N9～N16的5%的功率和N2、N5的10%的功率以及N8的25%的功率。當每個組單獨輸出時，剩下的則為每個輸出組的總和( 5V , 4A , 20W ) [1-2]。該轉(zhuǎn)換器在DCM模式下運行，而且它的開機工作周期（1天）是0.12。
3.1. 反激式變換器的常數(shù)設(shè)計
l 步驟1：計算主電感（LP）。
（1）
l 步驟2：計算關(guān)閉工作周期（D2)和最大旋轉(zhuǎn)次數(shù)（n），并且使關(guān)閉周期Dr的值為0.52，如圖1（b）所示。
==0.36 （2）
n==22.5 （3）
l 步驟3：計算主峰值（）和有效電流（)。
=0.926 （4）
=0.185 （5）
l 步驟4：計算二次均方根電流（）
（6）
l 步驟5：決定輸出電容（）
（7）
由于實際輸出是多個輸出,所以可以根據(jù)配方比例來計算出其電容值。
3.2. 反激式變換器的變壓器設(shè)計
下面的公式說明了鐵芯和變壓器繞組的直徑的計算和選擇，并且計算單元是基于CGS單位的。磁通量是以高斯和電流密度為基礎(chǔ)的，它的計算單位是基于A/cm。
l 步驟6：選擇變壓器的鐵芯
=0.288 （8）
l 步驟7：初級和次級繞組的計算（，）
=115轉(zhuǎn) （9） =4.77,轉(zhuǎn)5轉(zhuǎn) (10)
l 步驟8：計算表皮深度（）和主、副導線線尺寸（，）
表皮深度的計算（）：
=0.609 （11）
導線尺寸的計算（）：
（12）
(13)
經(jīng)過計算后，得出鐵芯的AP的值為=0.288cm，TDK的鐵芯EI25則被選擇成為單個輸出。因為電源的二次輸出是多輸出，EI25不能把所有的二次輸出放進里面，所以用來選擇鐵芯的步驟6至步驟8這幾步計算是需要重復執(zhí)行的。
l 步驟6（重復）：選擇變壓器的鐵芯
（14）
l 步驟7（重復）：初級和次級繞組的計算(,)
轉(zhuǎn) (15)
轉(zhuǎn) (16)
對于其他的次級繞組的轉(zhuǎn)數(shù)，使用公式來計算它們的值。
以下數(shù)據(jù)是二次旋轉(zhuǎn)經(jīng)過計算后的結(jié)果：轉(zhuǎn)了11轉(zhuǎn)，轉(zhuǎn)了11轉(zhuǎn)，轉(zhuǎn)了18轉(zhuǎn)，轉(zhuǎn)了11轉(zhuǎn)，轉(zhuǎn)了8轉(zhuǎn)，轉(zhuǎn)了18轉(zhuǎn)，轉(zhuǎn)了19轉(zhuǎn)，轉(zhuǎn)了11轉(zhuǎn)。實際繞組仍然是以電感為基礎(chǔ)的。
l 步驟10：步驟8：計算表皮深度（）和主、副導線的尺寸（、）
（17）
導線尺寸計算：
（18）
、、、、～在下面的計算中用帶有5%的總輸出功率來進行計算，、用帶有10%的總輸出功率來進行計算，用帶有25%的總輸出功率來進行計算，公式如下面的公式（19）所示。
（19）
，，， ，，，
，，。
考慮到輸出分叉以及變壓器繞組的需求，鐵芯EI25并沒有滿足這個要求。如果經(jīng)過計算后，求出的導線尺寸太薄，就不可能讓該導線作為變壓器的繞組，因此，最終的選擇將會是EER3928 FDK鐵電池。FDK的EER3928的AP的值為AP=1.956cm，繞組的面積大小為=146。由于仍然需要留有一些空間給鐵電池的窗口區(qū)域，所以把導線的大小修改為。在每一個次級導線尺寸的大小不應該大于表皮深度的最大尺寸的情況下，此時羅賓繞組區(qū)域才可以被最好的應用。在該情況下，的值取0.45，的值取0.2，的值取0.23，的值取0.45，的值取0.2，的值取0.2，的值取0.4且為雙繞組，的值取0.2，的值取0.23。
下一步是計算所有的繞組所需要的空間以及所有絕緣帶所需要的空間，以及鐵芯每一邊的長度值。因為導線的橫截面形狀是圓形的，所以在導線和絕緣帶之間的間隙中不可以再添加額外的導線，如圖2（a)所示。導線占用的繞組空間以正方形計算。每一個繞組單獨占用的空間大小，如下所示：=14.4，=0.81，=0.44，=0.58，=3.64，=0.44，=0.32，=5.76，=4.56，=0.58，整個繞組空間為至的總和，=31.5388。絕緣帶空間大小為，隔離層空間大小為，整個空間大小為。變壓器繞組的結(jié)果和變壓器的橫截面如圖2（b）所示。
4.控制器設(shè)計
逆變器應具有適當?shù)姆答伩刂?，從而來控制電源開關(guān)接通和關(guān)斷時間，維持穩(wěn)定的輸出電壓，PWM控制芯片采用了本文的UC3844。
4.1.反激式變換器主電路的小信號模型
反激變換器的小信號DCM模型等效電路如圖3（a）[3]所示。其中大寫字母指的是直流值，（即）是指小信號的變化值。在該電路當中：
，，，，，，。
4.2. 電流控制模式的小信號模型
在DCM模型中，每個周期中電感電流從0開始，并且和是沒有關(guān)聯(lián)的，但是、以及的斜率是互相關(guān)聯(lián)的，而且這些是DCM電流控制模型[3-5]的結(jié)果，同時塊圖3（b）顯示了不連續(xù)模式下的峰值電流控制。為補償器。
輸出電壓占空比的傳遞函數(shù)是[6]。根據(jù)圖6所示，開環(huán)傳遞函數(shù)表達式為：
為 （20）
同時，，，，，，。
下面的值是在公式（20）中經(jīng)過反激式轉(zhuǎn)換器中的常數(shù)計算而得出的結(jié)果，，，，，。與此同時，連續(xù)導通模式下的小信號分析的波德圖如圖4所示。
4.3. 不連續(xù)導通模式的補償器設(shè)計
從圖5和公式（20）中可獲得反激式轉(zhuǎn)換器的開環(huán)傳遞函數(shù)的零點和極點，圖1顯示了型號2的補償器設(shè)計，圖5顯示了型號2的補償器的伯德圖。
從不連續(xù)導通模式下的補償電路中可獲得補償器的傳遞函數(shù)，如圖8所示。
（21）
同時，，，，，
CTR是光耦的電流傳輸比，則是電壓增益。從圖4中可以獲得補償器的零點（127.877）和極點（1.66610），而且這種設(shè)計的反饋補償器的值為=1，=100，=100，，,，，，，，。該補償器的伯德圖如圖5所示。
圖6顯示了經(jīng)過補償設(shè)計之后的傳遞函數(shù)的波德圖。結(jié)果表明，經(jīng)過控制補償后，傳遞函數(shù)的波德圖一直處于穩(wěn)定的狀態(tài)，增益裕度的值為74.172dB,相位裕度的值為90.1°。
5. 仿真與實驗結(jié)果
最后，Powersim軟件是用來為多輸出電源模擬和測量每個電壓點和電流點的波形，模擬波形如圖7（a）所示。在仿真和實際電路的執(zhí)行之后，每個電壓的波形圖和電流的波形圖的測量如圖7（b）所示。
6. 結(jié)論
在本文中，采用反激式變換器為電動汽車控制電路來設(shè)計一個20W輸出電源，不連續(xù)導通模式的補償器則被設(shè)計用來使電動汽車有穩(wěn)定的多輸出電源。
致謝
感謝加入與豐富的電動共同合作研究項目:120990065, 研究力量和基金支持是非常重要的。
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