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电路设计->机动车 电动车电路图->汽车电子电路图->给汽车音频放大器供电的12V至正负20V的转换器电路

给汽车音频放大器供电的12V至正负20V的转换器电路

作者:dolphin时间:2014-07-28


  

给汽车音频放大器供电的12V至正负20V的转换器电路

在汽车电源电压(12V)内的限制力量电压转换为较高的功率音频放大器。
In fact the max audio power x speaker (with 4 ohm impedance) using 12V is (Vsupply+ - Vsupply-)^2/(8*impedance) 12^2/32 = 4.5Watts per channel, that is laughable...事实上,最大音频功率个扬声器(4欧姆阻抗)使用12V的是(Vsupply + - Vsupply -)^ 2 /(8 *阻抗)12 ^ 2 / 32 = 4.5Watts每通道,这是可笑的...
For powering correctly an amplifier the best is to use a symmetric supply with a high voltage differential.对于放大器供电正确最好是使用具有高电压差分对称供应。 for example +20 - -20 = 40Volts例如,20 - -20 = 40Volts
in fact事实上
40^2/32 = 50 Watts per channel that is respectable. 40 ^ 2 / 32 = 50瓦,每通道是可敬的。
This supply is intended for two channels with 50W max each (of course it depends on the amplifier used).这个供应量是为两个50瓦最大每个(当然,它取决于所用的放大器通道)。 Though it can be easily scaled up or the voltages changed to obtain different values.虽然可以很容易地扩充或更改为获得不同的值的电压。
概述-它是如何工作
It is a classic push-pull design , taking care to obtain best symmetry (to avoid flux walking).这是一个典型的推拉式设计,以获得最好的照顾对称(以避免流量步行)。 Keep in mind that this circuit will adsorb many amperes (around 10A) so take care to reinforce power tracks with lots of solder and use heavy wires from the battery or the voltage will drop too much at the input.请记住,这个赛道有很多吸附安培(约10A条),因此要注意加强与焊料的大量权力轨道和使用电池或电线的电压将下降沉重的输入太多。
The transformer must be designed to reduce skin effect, it can be done using several insulated magnet wire single wires soldered together but conducting separately.该变压器的设计必须减少皮肤的效果,这是可以做到使用几种漆包线绝缘单线进行焊接在一起,但分开。 The regulation is done both by the transformer turn ratio and varying the duty cycle.规例是由变压器匝比都和不同的占空比。 In my case i used 5+5 , 10+10 turns obtaining a step up ratio of 2 (12->24) and downregulating the voltage to 20 via duty cycle dynamic adjust performed by the PWM controller TL494.在我的情况下,我用5 +5,10 +10转取得了2:1(12 - “24)的步骤,通过占空比下调动态的电压调整执行的20个PWM控制器TL494。
The step-up ratio has to be a little higher to overcome diode losses, winding resistance and so on and input voltage drop due to wire resistance from battery to converter.在升压比例要略高于克服二极管损耗,绕组电阻等输入电压下降和由于导线,从电池到转换器的阻力。
 
Transformer design 变压器设计
The transformer must be of correct size in order to carry the power needed, on the net there are many charts showing the power in function of frequency and core size for a given topology.该变压器必须是正确的大小,以便进行网上显示有一个给定的拓扑结构,在核心频率和功率大小的功能很多图表电力需要。 My transformer size is 33.5 mm lenght, 30.0 height and 13mm width with a cross section area of 1,25cm^2, good for powers around 150W at 50khz.我的变压器的尺寸为33.5 mm长,30.0的高度和宽度13毫米的1,25厘米横截面积^ 2,在50KHz约150瓦的权力好。
The windings , especially the primary must be heavy gauged, but instead of using a single wire it is better to use绕组,特别是主要衡量必须沉重,而是使用了一个单线,最好是使用
multiple wires in parallel each insulated from the other except at the ends.同时在多条线路分别来自除在两端其他绝缘。 This will reduce resistance increase due to skin effect.这将减少阻力的增加,由于皮肤的效果。 The primary and secondary windings are centertapped, this means that you have to wind 5 turns, centertap and 5 windings again.小学和中学绕组centertapped,这意味着你必须风力5转,centertap和5绕组了。 The same goes for the secondary, 10 turns, centertap and 10 turns again.也是一样的中学,10转,centertap和10转了。
The important thing is that the transformer MUST not have air gaps or the leakage inductance will throw spikes on the switches overheating them and giving a voltage higher than expected by turn ratio prediction, so if your voltage output (at fully duty cycle) is higher than Vin*N2/N1 - Vdrop diode, your transformer has gap (of course permit me saying you that you are BLIND if you miss it), and this is accompanied with a drastical efficiency reduction.重要的是,变压器不能有气隙或漏感将引发他们对经济过热,给峰值开关电压高于预期转率的预测,因此如果您的电压输出(在充分占空比)高于葡萄酒* N2/N1 - Vdrop二极管,你的变压器有差距,当然(请允许我说你,你是盲目的,如果你错过了),这是与drastical效率,同时减少。 Use non-gapped E cores or toroids (ferrite).使用非核心或缺口的位置螺旋管(铁素体)。
 
Output diodes, capacitors and filter inductor 输出二极管,电容和滤波电感
For rectification i preferred to use shottky diodes since they have low forward voltage drop, and are incredibly fast.限期整改的首选一使用肖特基二极管,因为它们具有低正向电压降,并且非常快。
I used the cheap 1N5822, the best alternative for low voltage converters (3A for current capability).我使用了廉价的1N5822,对低电压转换器的电流能力(第3A最佳选择)。
The output capacitors are 4700uF 25V, not very big, since at high frequency the voltage ripple is most due to internal cap ESR fortunately general purpose lytics have enough low esr for a small ripple (some tens of millivolts).输出电容4700uF 25V的,不是很大,在高频电压纹波是最幸运的ESR由于通用lytics内部帽,因为有足够的小波纹低ESR(几十毫伏)。 Also at high duty cycle they are feed almost with pure DC, giving small ripple.此外饲料在高占空比它们几乎与纯直流,使小涟漪。 The filter inductor on the secondary centertap furter increases the ripple and helps the regulation in asymmetrical transients关于第二个centertap富尔特尔滤波电感增大了,并有助于在不对称瞬态调节

Power switch and driving 电源开关和驾驶
I used d2pak 70V 80A 0.004 ohms ultrafets (Fairchind semiconductor), very expensive and hard to find.采用D2PAK我用70V的80A条0.004欧姆ultrafets(Fairchind半导体),非常昂贵,而且很难找到。 In principle any fet will work, but the lower the on-resistance, the lower the on-state conduction losses, the lower the heat produced on the fets, the higher efficiency and smaller the heatsinks needed.原则上任何场效应管会的工作,但较低的电阻,较低的状态传导损失,更低的场效应管产生的热量,更高的效率和更小的散热需要。 With this fets i am able to run the fets with small heatsinks and without fan at full rated power (100W) with an efficiency of 82% and perceptible heating and with small heating at 120W (some degrees) (the core starts to saturate and the efficiency is a bit lower, around 75%)有了这个场效应管我能够运行在额定功率(100瓦)小散热片,没有风扇的场效应管在120W的是82%,并明显加热和小热效率(约度)(核心开始饱和的效率有点低75%左右)
Try to use the lowest resistance mosfet you can put your dirty hand :-) on or the efficiency will be lower than rated and you will need even a small fan.尝试使用最低的导通电阻MOSFET,您可以把您的工作效率或肮脏的手:-)将会比排名有所降低,你将有需要,即使一个小风扇。 The fet driver i used is the TPS2811P, from Texas instruments, rated for 2A peak and 200ns. Is important that the gate drive is optimized for minimal inductance or the switching losses will be higher and you risk noise coupling from other sources.场效应管驱动器,是我用了德州仪器TPS2811P,为2A峰值和200ns评价。重要的是,栅极驱动是最小电感或优化的开关损耗会更高,你可能从其他来源噪声耦合。 Personally i think that twisted pair wires (gate and ground/source) are the best to keep the inductance small.我个人认为,双绞线(门和地面/源)是最好的保持电感小。 Place the gate drive resistor near the Mosfet, not near the IC.广场附近的电阻MOSFET的栅极驱动器,而不是靠近集成电路。
Controller 控制器
I used the trusty TL494 PWM controller with frequency set at around 40-60 Khz adjustable with a potentiometer.我使用的频率信赖TL494 PWM控制器40-60千赫左右的电位器调节设置。 I also implemented the soft start (to reduce powerup transients).我还实施了软启动(以减少上电瞬态)。 The adjust potentiometer (feedback) must be set to obtain the desired voltage.在调整电位(反馈)必须设置为获得所需的电压。 The output signals is designed with two pull-up resistors on the collector of the PWM chip output transistor pulling them to ground each cycle alternatively.输出信号设计了两个上拉的PWM芯片输出拉他们到地每一个周期轮流晶体管的集电极电阻。 This signal is sent to the dual inverting MOSFET driver (TPS2811P) obtaining the correct waveform.这个信号发送到双反相MOSFET驱动器(TPS2811P)获取正确的波形。

Power and filtering 电源和滤波
How i said before the power tracks must be heavy gauged or you will scarify regulation (since it depends of transformer step up ratio and input voltage) and efficiency too.怎么我以前说过的权力轨道,必须重来衡量,否则您将划破条例(自定)和效率也最高比例,输入电压互感器的一步。 Don't forget to place a 10A (or 15A) fuse on the input because the car batteries can supply very high currents in case of shorts and this will save you face from a mosfet explosion in case of failture or short, remember to place a fuse also on the battery side to increase the safety (accidental shorts->fire, battery explosion, firemen, police and lawyers around).不要忘了把一10A条(或第15A)保险丝的输入,因为汽车电池可提供在短裤下极高的电流,这将节省您从在功能衰竭或短爆炸案MOSFET的脸,记得把一还对电池方融合,以增加安全性(意外短路,“火灾,电池爆炸,消防员,警察和各地律师)。 Input filtering is important, use at least 20000uF 16V in capacitors, a filter inductor would be useful too (heavygauged) but i decided to leave it..输入过滤是重要的,使用电容器至少20000uF 16V的,一滤波电感也将是有益的(heavygauged),但我决定离开这..
Final considerations 最后考虑
This supply given me up to 85% efficiency (sometimes even 90% at some loads) with an input of 12V because i observed all these tricks to keep it functional and efficient.给我85%的效率(90%,有时甚至在一些负载与输入为12V),这个供应量,因为我发现所有这些技巧来保持它的功能和效率。 An o-scope would be useful, to watch the ripple and gate signals (watching for overshoots), but if you follow these guidelines you will avoid these problems.一个O -范围将是有益的,观看纹波和门信号(用于超调看),但如果您遵循以下原则,你可以避免这些问题。
The cross regulation is good but keep in mind that only the positive output is fully regulated, and the negative only follows it.跨调控是好的,但要记住,只有积极的输出完全调节,负只能跟随它。 Place a small load between the negative rail and ground (a 3mm led with a 4.7Kohm resistor) to avoid the negative rail getting lower then -20V.地方之间的负铁路和地面小负载(1毫米的4.7Kohm电阻领导),以避免负面铁路越来越低,然后- 20V的。 If the load is asymmetric you can have two cases:如果负载不对称,您可以有两种情况:
-More load on positive rail-> no problems, the negative rail can go lower than -20V, but it is not a real issue for an audio amplifier. ,更多的负载正面轨“没有问题,负铁路可以低于- 20V的,但它不是一个真正的问题音频放大器。
-More load on negative rail-> voltage drop on negative rail (to ground) especially if the load is only on the negative rail. ,更多的负载负轨“铁路的负电压降(接地),特别是当负载只负轨道。
Fortunately audio amplifiers are quite symmetrical as a load, and the output filter inductor/capacitors helps to maintain the regulation good during asymmetrical transients (Basses)幸运的是音频放大器相当对称的负载,输出滤波电感/电容有助于维持在(贝司不对称的瞬态调节好)

ATTENTION 注意
Keep in mind that THIS IS NOT A PROJECT FOR A BEGINNER , I T CAN BE VERY DANGEROUS IN CASE OF PROBLEMS, NEVER BRIDGE, BYPASS OR AVOID FUSES THESE WILL SAVE YOUR BACK FROM FIRE RISK. 请记住 , 这是不是一个项目对于初学者可在的问题,从来没有桥,绕过或避免保险丝这些案例非常危险将保存您返回火灾的危险性,我吨 。

FOR FIRST TESTING USE A SMALL 12V power supply and use resistors as load monitoring switches heat and current consumption (and output) and try to determine efficiency, if it is higher then 70-75% you are set, it is enough. 的第一次核试验使用小12V电源供应和使用电阻器的热负荷监控开关和电流消耗(和输出),并试图确定的效率,如果是高70-75%,然后你设置,这是不够的。 Adjust the frequency for best compromise between power and switching losses, skin effect and hysteresis losses调整频率之间的最佳功率和开关损耗,趋肤效应和滞后损失妥协

Bill Of Materials 材料清单
================= =================
Design: 12V to 20V 100W DC-DC conv设计:12V至20V 100W的直流换
Doc.文件。 no.: 1没有。:1
Revision: 3版次:3
Author: Jonathan Filippi作者:Jonathan菲利皮巴莱
Created: 29/04/05建立日期:29/04/05
Modified: 18/05/05修改:18/05/05
Parts List 零件清单
--- --------- ----- --- --------- -----
Resistors 电阻
--------- ---------
2 R1,R2 = 10 2为R1,R2 = 10
4 R3,R4,R6,R7 = 1k 4 R3,R4的,R6的,r7同样=经销商
1 R5 = 22k 1 R5 = 22k
1 R8 = 4.7k 1奥迪R8 = 4.7K的
1 R9 = 100k 1九号= 10万
Capacitors 电容器
---------- ----------
2 C1,C2 = 10000uF 2 C1组,C2 = 10000uF
2 C3,C6 = 47u 2补体C3,型2号= 47u
1 C4 = 10u 1 C4 = 10U的
3 C5,C7,C14 = 100n 3碳五,C7处理器,十四碳= 100n
2 C8,C9 = 4700u 2,C8脂随着c9 = 4700u
1 C12 = 1n 1十二碳= ·在
1 C13 = 2.2u 1碳13 = 2.2u
Integrated Circuits 集成电路
------------------- -------------------
1 U1 = TL494 1 U1的= TL494
1 U2 = TPS2811P 1 U2乐队= TPS2811P
Transistors 晶体管
----------- -----------
2 Q1,Q2 = FDB045AN二季度,第二季度= FDB045AN
Diodes 二极管
------ ------
4 D1-D4 = 1N5822 4 D1的- D4类= 1N5822
1 D5 = 1N4148 1 D5 = 1N4148
Miscellaneous 杂项
------------- -------------
1 FU1 = 10A 1富1 = 10A条
1 L1 = 10u 1母语= 10U的
1 L2 = FERRITE BEAD 1二级=磁珠
1 RV1 = 2.2k 1 RV1 = 2.2k的
1 RV2 = 24k 1 RV2 =足金


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