I ran a long USB extension cable from my pc to a WiFi adapter. The cable was too long and the gauge was too thin. So the resistance made the voltage drop to ~3V under load, making the WiFi adapter disconnect. To overcome the voltage drop, I devised this:
我从我的电脑上运行了一条长USB延长线到一个WiFi适配器。电缆太长，仪表太薄。因此，电阻使负载下的电压降至~3V，使WiFi适配器断开。为了克服电压降，我设计了这个：
I snapped the USB extension cord's power cables (the data cables were kept intact) and ran them through a 0.9-4.5 to 5V boost converter capable of handling 1 Amp at input (the WiFi adapter takes 300mAmp max at 5V as measured by USB doctor.)
我拍下了USB延长线的电源线（数据线完好无损）并通过一个0.9-4.5到5V的升压转换器运行它们，输入端能够处理1安培（由USB医生测量，WiFi适配器在5V时最大需要300mAmp。 ）
Now one would think that this setup would work. Kind of like voltage stabilizers that step up low.voltages of household. But it didn't work. I can't find out why. Whenever the WiFi adapter kicks in, the input voltage drops to 1.5V and the booster can't keep up with the power demand. Why is this happening? The same principle is used for stabilizers of households where the voltage is low. So why don't stabilizers trip like this USB booster is doing?
现在人们会认为这种设置会起作用。有点像电压稳定器，它们会降低家庭电压。但它没有用。我找不到原因。每当WiFi适配器启动时，输入电压降至1.5V，并且助推器无法满足电力需求。为什么会这样？同样的原理用于电压低的家庭的稳定器。那么为什么不像这样的USB助推器那样的稳定器行程呢？
4 个解决方案
#1
8
You have discovered the negative resistance feature that occurs with switch mode regulators.
您已经发现了开关模式稳压器出现的负阻功能。
This is a very simplified explanation of what is going on. For all intents and purposes and assuming a fixed load, you can consider the regulator to be a constant-power device. If the input voltage increases, the input current decreases. The opposite occurs when the input voltage decreases - the input current increases.
这是对正在发生的事情的非常简化的解释。对于所有意图和目的并假设固定负载，您可以将调节器视为恒功率设备。如果输入电压增加，则输入电流减小。当输入电压降低时 - 输入电流增加，则相反。
Now consider what happens when the load current increases. The input current has to increase to handle increased load current. But: the resistance of the USB cable means that the input voltage decreases. Recall that I mentioned that the input current has to Increase when the input voltage drops.
现在考虑当负载电流增加时会发生什么。必须增加输入电流以处理增加的负载电流。但是：USB电缆的电阻意味着输入电压降低。回想一下，我提到当输入电压下降时输入电流必须增加。
This is a vicious cycle and results with the voltage input to the regulator dropping to a very low value.
这是一个恶性循环，导致调节器的电压输入降至非常低的值。
There are a couple of ways to fix the problem.
有几种方法可以解决这个问题。
1) Add a pair of heavy wires in parallel with the power conductors of the USB cable.
1）将一对重电线与USB电缆的电源导线并联。
2) Use a boost converter at the source end of the USB cable, followed by a buck converter at the load end. In other words, feed the power input of the USB cable with a voltage that is high enough to overcome the wire resistance.
2）在USB电缆的源端使用升压转换器，然后在负载端使用降压转换器。换句话说，用足够高的电压馈送USB电缆的电源输入以克服导线电阻。
#2
0
A voltage-output boost converter also boosts input current by as much the voltage ratio that it is capable of boosting to support the power rating. Normally, the boost draws current then flyback a higher voltage at a variable frequency depending on load. However the charge current could have a crest factor of >5x that is normally dampened by a low ESR input bulk cap. However if the USB source impedance added to the cable resistance does not permit the boost current to rise fast enough, the output fails to achieve regulation.
电压输出升压转换器还可将输入电流提升至其能够提升的电压比以支持额定功率。通常，升压电流吸收电流，然后根据负载以可变频率反激更高的电压。然而，充电电流可能具有> 5x的波峰因数，通常由低ESR输入体积电容衰减。但是，如果添加到电缆电阻的USB源阻抗不允许升压电流足够快地上升，则输出无法实现调节。
I would add a large bulk input storage cap sized according to potential PTC poly resistor fuses such that they do not trip if using heavier DC cable does not fix it.
我会根据潜在的PTC多晶硅电阻保险丝添加一个大的大容量输入存储帽，如果使用较重的直流电缆不能修复它们，它们就不会跳闸。
#3
0
You should read the USB standards, which states that 2 meters is the maximum cable length (with present standards). It has nothing to do with power so much as power supplies made now days can boost the voltage as high as 27 volts, and there is talk of a 48 volt version.
您应该阅读USB标准，其中规定2米是最大电缆长度（符合现行标准）。它与电源无关，因为现在制造的电源可以提升高达27伏的电压，而且有48伏特版本的说法。
Adding a boost converter is dangerous as the device must request a specific voltage from the more advanced power supplies. If you just want a long distance charge ability then just bypass the existing power/ground wires in the USB cable with much heavier gauge wire. 10 Awg should be good enough.
添加升压转换器很危险，因为设备必须从更高级的电源请求特定电压。如果您只是想要一个长距离充电能力，那么只需绕过USB电缆中现有的电源/地线，并使用更粗的电线。 10 Awg应该足够好了。
USB packet timing is 1 millisecond apart. If an endpoint device cannot respond to queries within 1 ms its connection is terminated as if it had been unplugged. Unlike Ethernet, USB does not have the complex speed management algorithms or a "push back" function to slow down the data stream or adjust packet size and timing.
USB数据包时序相隔1毫秒。如果端点设备在1毫秒内无法响应查询，则其连接将被终止，就像它已被拔出一样。与以太网不同，USB没有复杂的速度管理算法或“推回”功能来减慢数据流速度或调整数据包大小和时序。
A USB cable has a higher capacitance per meter than Cat-5 Ethernet, so even at 2 meters it has severe speed and current limits. USB-C works around this with 4 pairs of data channels instead of 1 plus higher voltage options. One mS seems like a long time to CAT-5 cable, but for current standard USB cables 4 meters would be a problem. USB-C proves that there is an effort to get past power and speed limits, but current cable designs put a severe limit on length, even at the lowest standard speed.
USB线缆的电容每米比Cat-5以太网更高，因此即使在2米处它也具有严格的速度和电流限制。 USB-C可以通过4对数据通道解决这个问题，而不是1对更高电压选项。对于CAT-5电缆来说，一个mS似乎需要很长时间，但对于目前的标准USB电缆，4米将是一个问题。 USB-C证明了努力超越功率和速度限制，但目前的电缆设计严格限制了长度，即使在最低标准速度下也是如此。
Making a USB cable 4 meters long can violate this nitpicky timing rule. It may be ok for charging purposes though some power loss will occur.
制作4米长的USB电缆可能会违反这种挑剔的时序规则。尽管会出现一些功率损耗，但充电可能没问题。
#4
-1
Why doesn't a boost converter help overcome USB cable resistance?
为什么升压转换器不能帮助克服USB电缆电阻？
I ran a long USB extension cable from my PC to a WiFi adapter.
我从PC上运行了一条长USB延长线到一个WiFi适配器。
Note that not all PC USB ports are specced to deliver a full 2A or special charging voltages over USB. I use Rampage Extreme motherboards, which are relatively top of the line for a desktop, and even on these a few extra steps have to be taken to enable it's full USB function. Even with this function enabled, note that USB port power is likely ganged together onto rails, in which case spreading high power usb devices across rails may be necessary. It's probably not a bad idea to measure the resistance of your cable and make sure that your voltage drop can be accounted for. If you're losing 2v at 300mA, you should have about 6.66 ohms.
请注意，并非所有PC USB端口都可通过USB提供完整的2A或特殊充电电压。我使用Rampage Extreme主板，它们是台式机的*产品，即使在这些主板上也必须采取一些额外的步骤才能实现完整的USB功能。即使启用了此功能，请注意USB端口电源可能会一起组装到轨道上，在这种情况下，可能需要在轨道上传播高功率USB设备。测量电缆的电阻并确保降低电压可能并不是一个坏主意。如果你在300mA时损失2v，你应该有大约6.66欧姆。
The cable was too long and the gauge was too thin. So the resistance made the voltage drop to ~3V under load, making the WiFi adapter disconnect.
电缆太长，仪表太薄。因此，电阻使负载下的电压降至~3V，使WiFi适配器断开。
This is probably the best place to attack the problem. Use better cable, possibly make your own. If you really want premade, shielding would help, and a single cable of a given length is more likely to have lower impedance.
这可能是解决问题的最佳场所。使用更好的电缆，可能自己做。如果您真的想要预制，屏蔽会有所帮助，并且给定长度的单根电缆更可能具有更低的阻抗。
To overcome the voltage drop, I devised this:
为了克服电压降，我设计了这个：
I snapped the USB extension cord's power cables (the data cables were kept intact) and ran them through a 0.9-4.5 to 5V boost converter capable of handling 1 Amp at input (the WiFi adapter takes 300mAmp max at 5V as measured by USB doctor.)
我拍下了USB延长线的电源线（数据线完好无损）并通过一个0.9-4.5到5V的升压转换器运行它们，输入端能够处理1安培（由USB医生测量，WiFi适配器在5V时最大需要300mAmp。 ）
Well, it was worth a shot, and you still may be able to pull it off, however, show us specs for the boost converter you chose. Lots of switching converters' efficiencies decreases at lower loads, so at 300mA @ 5V @ .7 efficiency will require 2.14 VA, so 714mA at 3V. One other thing to note is that a boost converter combined with an inadequate source will keep pulling more current at lower voltage to support it's output, so if load regulation is a problem in the first place, the boost converter will aggravate it.
好吧，它值得一试，你仍然可以把它拉下来，但是，向我们展示你选择的升压转换器的规格。很多开关转换器的效率在较低负载时会降低，因此在@ 5V时为300mA .7。效率将需要2.14 VA，因此在3V时需要714mA。还有一点需要注意的是，升压转换器与不充足的电源相结合将在较低电压下继续吸收更多电流以支持其输出，因此如果负载调节首先成为问题，则升压转换器会加剧它。
Now one would think that this setup would work. Kind of like voltage stabilizers that step up low.voltages of household. But it didn't work. I can't find out why. Whenever the WiFi adapter kicks in, the input voltage drops to 1.5V and the booster can't keep up with the power demand. Why is this happening?
现在人们会认为这种设置会起作用。有点像电压稳定器，它们会降低家庭电压。但它没有用。我找不到原因。每当WiFi适配器启动时，输入电压降至1.5V，并且助推器无法满足电力需求。为什么会这样？
Yep, that sounds like a load regulation problem. The voltage source in your computer is just unable to output enough total power, and a high resistance cable and boost converter are aggravating the problem.
是的，这听起来像负载调节问题。计算机中的电压源无法输出足够的总功率，高阻抗电缆和升压转换器会加剧问题。
The same principle is used for stabilizers of households where the voltage is low.
同样的原理用于电压低的家庭的稳定器。
All wires in a house are adequately sized and also current protected, and line voltage from the power company generally has good regulation, so giving a small voltage updoot would not be a big problem, however, normal practice for large voltage drops is to go to higher voltage and/or larger wire to reduce losses.
房屋内的所有电线都有足够的尺寸和电流保护，来自电力公司的线路电压通常具有良好的调节性能，因此提供小电压升压不会是一个大问题，但是，大电压降的正常做法是去更高的电压和/或更大的电线，以减少损失。
So why don't stabilizers trip like this USB booster is doing?
那么为什么不像这样的USB助推器那样的稳定器行程呢？
The stabilizer is not being used so much as a signal booster as it is as an active filter. It has an adequate power source, or in cases where it doesn't, it will also be unable to maintain output. The root cause of the problem in some countries is inadequacy of the electrical network in the first place, which could include both the distribution lines and the sources, but in these cases, the AC stabilizers would basically increase the share of the total power that it's output received and use more power in the process. This means when the source is inadequate, that all of the lines with a stabilizer on them would be aggravating brownout on all of the lines without a stabilizer, same as a boost converter is aggravating the problem in your circuit.
稳定器不像信号增强器那样被用作有源滤波器。它有足够的电源，或者在没有电源的情况下，它也将无法保持输出。一些国家问题的根本原因是电网首先不足，可能包括配电线路和电源，但在这些情况下，交流稳压器基本上会增加其总功率的份额。收到输出并在此过程中使用更多功率。这意味着当光源不足时，所有带有稳定器的线路都会在没有稳定器的情况下加剧所有线路的欠压，与升压转换器相同会加剧电路中的问题。
#1
8
You have discovered the negative resistance feature that occurs with switch mode regulators.
您已经发现了开关模式稳压器出现的负阻功能。
This is a very simplified explanation of what is going on. For all intents and purposes and assuming a fixed load, you can consider the regulator to be a constant-power device. If the input voltage increases, the input current decreases. The opposite occurs when the input voltage decreases - the input current increases.
这是对正在发生的事情的非常简化的解释。对于所有意图和目的并假设固定负载，您可以将调节器视为恒功率设备。如果输入电压增加，则输入电流减小。当输入电压降低时 - 输入电流增加，则相反。
Now consider what happens when the load current increases. The input current has to increase to handle increased load current. But: the resistance of the USB cable means that the input voltage decreases. Recall that I mentioned that the input current has to Increase when the input voltage drops.
现在考虑当负载电流增加时会发生什么。必须增加输入电流以处理增加的负载电流。但是：USB电缆的电阻意味着输入电压降低。回想一下，我提到当输入电压下降时输入电流必须增加。
This is a vicious cycle and results with the voltage input to the regulator dropping to a very low value.
这是一个恶性循环，导致调节器的电压输入降至非常低的值。
There are a couple of ways to fix the problem.
有几种方法可以解决这个问题。
1) Add a pair of heavy wires in parallel with the power conductors of the USB cable.
1）将一对重电线与USB电缆的电源导线并联。
2) Use a boost converter at the source end of the USB cable, followed by a buck converter at the load end. In other words, feed the power input of the USB cable with a voltage that is high enough to overcome the wire resistance.
2）在USB电缆的源端使用升压转换器，然后在负载端使用降压转换器。换句话说，用足够高的电压馈送USB电缆的电源输入以克服导线电阻。
#2
0
A voltage-output boost converter also boosts input current by as much the voltage ratio that it is capable of boosting to support the power rating. Normally, the boost draws current then flyback a higher voltage at a variable frequency depending on load. However the charge current could have a crest factor of >5x that is normally dampened by a low ESR input bulk cap. However if the USB source impedance added to the cable resistance does not permit the boost current to rise fast enough, the output fails to achieve regulation.
电压输出升压转换器还可将输入电流提升至其能够提升的电压比以支持额定功率。通常，升压电流吸收电流，然后根据负载以可变频率反激更高的电压。然而，充电电流可能具有> 5x的波峰因数，通常由低ESR输入体积电容衰减。但是，如果添加到电缆电阻的USB源阻抗不允许升压电流足够快地上升，则输出无法实现调节。
I would add a large bulk input storage cap sized according to potential PTC poly resistor fuses such that they do not trip if using heavier DC cable does not fix it.
我会根据潜在的PTC多晶硅电阻保险丝添加一个大的大容量输入存储帽，如果使用较重的直流电缆不能修复它们，它们就不会跳闸。
#3
0
You should read the USB standards, which states that 2 meters is the maximum cable length (with present standards). It has nothing to do with power so much as power supplies made now days can boost the voltage as high as 27 volts, and there is talk of a 48 volt version.
您应该阅读USB标准，其中规定2米是最大电缆长度（符合现行标准）。它与电源无关，因为现在制造的电源可以提升高达27伏的电压，而且有48伏特版本的说法。
Adding a boost converter is dangerous as the device must request a specific voltage from the more advanced power supplies. If you just want a long distance charge ability then just bypass the existing power/ground wires in the USB cable with much heavier gauge wire. 10 Awg should be good enough.
添加升压转换器很危险，因为设备必须从更高级的电源请求特定电压。如果您只是想要一个长距离充电能力，那么只需绕过USB电缆中现有的电源/地线，并使用更粗的电线。 10 Awg应该足够好了。
USB packet timing is 1 millisecond apart. If an endpoint device cannot respond to queries within 1 ms its connection is terminated as if it had been unplugged. Unlike Ethernet, USB does not have the complex speed management algorithms or a "push back" function to slow down the data stream or adjust packet size and timing.
USB数据包时序相隔1毫秒。如果端点设备在1毫秒内无法响应查询，则其连接将被终止，就像它已被拔出一样。与以太网不同，USB没有复杂的速度管理算法或“推回”功能来减慢数据流速度或调整数据包大小和时序。
A USB cable has a higher capacitance per meter than Cat-5 Ethernet, so even at 2 meters it has severe speed and current limits. USB-C works around this with 4 pairs of data channels instead of 1 plus higher voltage options. One mS seems like a long time to CAT-5 cable, but for current standard USB cables 4 meters would be a problem. USB-C proves that there is an effort to get past power and speed limits, but current cable designs put a severe limit on length, even at the lowest standard speed.
USB线缆的电容每米比Cat-5以太网更高，因此即使在2米处它也具有严格的速度和电流限制。 USB-C可以通过4对数据通道解决这个问题，而不是1对更高电压选项。对于CAT-5电缆来说，一个mS似乎需要很长时间，但对于目前的标准USB电缆，4米将是一个问题。 USB-C证明了努力超越功率和速度限制，但目前的电缆设计严格限制了长度，即使在最低标准速度下也是如此。
Making a USB cable 4 meters long can violate this nitpicky timing rule. It may be ok for charging purposes though some power loss will occur.
制作4米长的USB电缆可能会违反这种挑剔的时序规则。尽管会出现一些功率损耗，但充电可能没问题。
#4
-1
Why doesn't a boost converter help overcome USB cable resistance?
为什么升压转换器不能帮助克服USB电缆电阻？
I ran a long USB extension cable from my PC to a WiFi adapter.
我从PC上运行了一条长USB延长线到一个WiFi适配器。
Note that not all PC USB ports are specced to deliver a full 2A or special charging voltages over USB. I use Rampage Extreme motherboards, which are relatively top of the line for a desktop, and even on these a few extra steps have to be taken to enable it's full USB function. Even with this function enabled, note that USB port power is likely ganged together onto rails, in which case spreading high power usb devices across rails may be necessary. It's probably not a bad idea to measure the resistance of your cable and make sure that your voltage drop can be accounted for. If you're losing 2v at 300mA, you should have about 6.66 ohms.
请注意，并非所有PC USB端口都可通过USB提供完整的2A或特殊充电电压。我使用Rampage Extreme主板，它们是台式机的*产品，即使在这些主板上也必须采取一些额外的步骤才能实现完整的USB功能。即使启用了此功能，请注意USB端口电源可能会一起组装到轨道上，在这种情况下，可能需要在轨道上传播高功率USB设备。测量电缆的电阻并确保降低电压可能并不是一个坏主意。如果你在300mA时损失2v，你应该有大约6.66欧姆。
The cable was too long and the gauge was too thin. So the resistance made the voltage drop to ~3V under load, making the WiFi adapter disconnect.
电缆太长，仪表太薄。因此，电阻使负载下的电压降至~3V，使WiFi适配器断开。
This is probably the best place to attack the problem. Use better cable, possibly make your own. If you really want premade, shielding would help, and a single cable of a given length is more likely to have lower impedance.
这可能是解决问题的最佳场所。使用更好的电缆，可能自己做。如果您真的想要预制，屏蔽会有所帮助，并且给定长度的单根电缆更可能具有更低的阻抗。
To overcome the voltage drop, I devised this:
为了克服电压降，我设计了这个：
I snapped the USB extension cord's power cables (the data cables were kept intact) and ran them through a 0.9-4.5 to 5V boost converter capable of handling 1 Amp at input (the WiFi adapter takes 300mAmp max at 5V as measured by USB doctor.)
我拍下了USB延长线的电源线（数据线完好无损）并通过一个0.9-4.5到5V的升压转换器运行它们，输入端能够处理1安培（由USB医生测量，WiFi适配器在5V时最大需要300mAmp。 ）
Well, it was worth a shot, and you still may be able to pull it off, however, show us specs for the boost converter you chose. Lots of switching converters' efficiencies decreases at lower loads, so at 300mA @ 5V @ .7 efficiency will require 2.14 VA, so 714mA at 3V. One other thing to note is that a boost converter combined with an inadequate source will keep pulling more current at lower voltage to support it's output, so if load regulation is a problem in the first place, the boost converter will aggravate it.
好吧，它值得一试，你仍然可以把它拉下来，但是，向我们展示你选择的升压转换器的规格。很多开关转换器的效率在较低负载时会降低，因此在@ 5V时为300mA .7。效率将需要2.14 VA，因此在3V时需要714mA。还有一点需要注意的是，升压转换器与不充足的电源相结合将在较低电压下继续吸收更多电流以支持其输出，因此如果负载调节首先成为问题，则升压转换器会加剧它。
Now one would think that this setup would work. Kind of like voltage stabilizers that step up low.voltages of household. But it didn't work. I can't find out why. Whenever the WiFi adapter kicks in, the input voltage drops to 1.5V and the booster can't keep up with the power demand. Why is this happening?
现在人们会认为这种设置会起作用。有点像电压稳定器，它们会降低家庭电压。但它没有用。我找不到原因。每当WiFi适配器启动时，输入电压降至1.5V，并且助推器无法满足电力需求。为什么会这样？
Yep, that sounds like a load regulation problem. The voltage source in your computer is just unable to output enough total power, and a high resistance cable and boost converter are aggravating the problem.
是的，这听起来像负载调节问题。计算机中的电压源无法输出足够的总功率，高阻抗电缆和升压转换器会加剧问题。
The same principle is used for stabilizers of households where the voltage is low.
同样的原理用于电压低的家庭的稳定器。
All wires in a house are adequately sized and also current protected, and line voltage from the power company generally has good regulation, so giving a small voltage updoot would not be a big problem, however, normal practice for large voltage drops is to go to higher voltage and/or larger wire to reduce losses.
房屋内的所有电线都有足够的尺寸和电流保护，来自电力公司的线路电压通常具有良好的调节性能，因此提供小电压升压不会是一个大问题，但是，大电压降的正常做法是去更高的电压和/或更大的电线，以减少损失。
So why don't stabilizers trip like this USB booster is doing?
那么为什么不像这样的USB助推器那样的稳定器行程呢？
The stabilizer is not being used so much as a signal booster as it is as an active filter. It has an adequate power source, or in cases where it doesn't, it will also be unable to maintain output. The root cause of the problem in some countries is inadequacy of the electrical network in the first place, which could include both the distribution lines and the sources, but in these cases, the AC stabilizers would basically increase the share of the total power that it's output received and use more power in the process. This means when the source is inadequate, that all of the lines with a stabilizer on them would be aggravating brownout on all of the lines without a stabilizer, same as a boost converter is aggravating the problem in your circuit.
稳定器不像信号增强器那样被用作有源滤波器。它有足够的电源，或者在没有电源的情况下，它也将无法保持输出。一些国家问题的根本原因是电网首先不足，可能包括配电线路和电源，但在这些情况下，交流稳压器基本上会增加其总功率的份额。收到输出并在此过程中使用更多功率。这意味着当光源不足时，所有带有稳定器的线路都会在没有稳定器的情况下加剧所有线路的欠压，与升压转换器相同会加剧电路中的问题。