Discussion on current detection scheme of wind-solar hybrid system

jishuaihu

Discussion on current detection scheme of wind-solar hybrid system [Copy link]

The wind-solar hybrid system is a system that uses wind power generation and photovoltaic power generation to power the system. It is generally used to power remote places, such as the wild, isolated islands, etc. The figure below shows the basic structure of a small power system. Power supply 1 and power supply 2 are photovoltaic power generation and wind turbines respectively. Although this type of application is simple, the power supply and load involved are a little complicated. The two power supplies can only supply power, and the battery can be both a power supply device and a power-consuming device. In the current detection method shown in the figure below, the signal detected at the battery current detection position is in both positive and negative directions relative to GND. The signals detected by power supply 1 and power supply 2 are negative to the ground. In this case, if the current detection signal is amplified, a positive and negative power supply is required, right? Is there a simpler detection method? Everyone is welcome to discuss~

maychang

"In this case, if the current detection signal is amplified, positive and negative power supplies are required, right? Is there a simpler detection method?" Generally speaking, this is the case. However, some op amps can still work normally when the input terminal is slightly lower than the negative terminal of the power supply (using the "ground" of a single power supply). However, this can only be regarded as a special case.

jishuaihu

maychang published on 2018-1-15 16:20 "In this case, if the current detection signal is amplified, positive and negative power supplies are required, right? Is there a simpler detection method?" Generally...

The lowest input of a general op amp can be a little lower than the negative input of the power supply, but I am not sure whether it can work properly and I have not tried it. Is there a simpler signal processing method for applications like this? Positive and negative power supplies will increase the cost of a single-power supply system. Is there a low-cost solution?

chunyang

Such a system should give priority to reliability, even if it costs a little more. For systems with high maintenance costs, full consideration should be given during design.

jishuaihu

chunyang posted on 2018-1-15 23:04 For such a system, reliability should be given priority, and it is okay to increase the cost for this. For systems with high maintenance costs, full consideration should be given during design.

I understand this. But it is a different story for users. Two solutions were considered. One is to use a charge pump. TI's TPS6040x is quite suitable, but the voltage input range is a bit small, with a maximum of only 5.5V. The other option is to add a power supply to the power module.

maychang

jishuaihu posted on 2018-1-15 22:43 Generally, the lowest input of an op amp can be a little lower than the negative input of the power supply, but I am not sure whether it can work properly, and I have not tried it. Similar to this...

"Is there a simpler signal processing method for applications like this?" Add a stable positive voltage to the voltage across R3, and the sum can always be positive. If AD conversion is performed after amplification, the conversion result can be subtracted from this fixed offset (of course, multiplied by the amplification factor). However, adding first and then subtracting will increase the error.

jishuaihu

At the critical moment, the two god-level moderators are still reliable. I have also considered their opinions, and it seems that there are basically several solutions. Roll up your sleeves and get to work! ! ! !

lct2000

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