How can I detect whether there is 220V input with the lowest power consumption?

sky999

How can I detect whether there is 220V input with the lowest power consumption? [Copy link]

 

How can I detect whether there is 220V input with the lowest power consumption?

Assuming that an optocoupler is used to detect 5V1MA, it is only 0.005W. However, if an optocoupler is used to detect 220V1MA, it will waste about 0.2W of electricity. Is there any way to reduce power consumption?

maychang

Using a voltage transformer can reduce the power consumption. Of course, voltage transformers are not cheap and are relatively large.

Note: This is not a transformer with a resistor in series with the primary winding. That kind of transformer is actually a 2mA:2mA current transformer.

maychang

Another way to reduce power dissipation is to use capacitors to drop the voltage.

qwqwqw2088

How low is the power consumption? What are the requirements for power consumption?

To detect 220V AC power in a DC circuit, isolation devices such as optocouplers and transformers are required.

chunyang

What is the final detection element? What is the specific application? Without these important premises, it is impossible to determine the best solution.

仙猫

A few tenths of a watt more of AC200V mains power consumption is nothing at all. Whether it is necessary to deliberately pursue ultra-low power consumption is worth discussing. Instead, we should think about whether there are any accuracy requirements for the detection voltage. For example, is it considered "220V" when it is plugged into a 100V socket?

sky999

maychang posted on 2020-6-13 06:29 Using a voltage transformer can reduce the power consumption. Of course, the voltage transformer is not cheap and is relatively large. Note: It is not a primary winding series...

Um, I have never used a transformer. Does 2mA refer to 220V2mA? Or does it refer to the 2mA voltage converted by the transformer?

sky999

maychang posted on 2020-6-13 06:30 Another way to reduce power dissipation is to use capacitors to reduce voltage.

How to use capacitors to reduce voltage? It is best to use capacitors with smaller size.

sky999

qwqwqw2088 posted on 2020-6-13 08:11 How low is the power consumption? What are the requirements for power consumption? If a DC circuit needs to detect 220V AC power, it needs isolation devices such as optocouplers and transformers

I just want to detect whether there is a 220V input for home appliances at a certain terminal. However, because the detection is for a long time, I calculated that if 0.2W disappears out of thin air every hour, it is also a waste, just like throwing away 2 cents every hour. Although it is not a lot of money, it is also thrown away all the time. I want to see if there is a solution with lower power consumption.

sky999

chunyang posted on 2020-6-13 23:41 What is the final detection element? What is the specific application? Without these important premises, it is impossible to determine the best solution.

For household appliances, it is not the detection component, but the IO port of the microcontroller that detects whether there is 220V input externally.

sky999

Xianmao published on 2020-6-15 09:54 It is nothing to spend a few tenths of a watt on AC200V mains electricity. Whether it is necessary to deliberately pursue ultra-low power consumption is worth discussing. Instead, we should think about whether there is any need for the detection voltage...

Because the detection is maintained for a long time, if 1 channel detection consumes 0.2W of power, 10 channels consumes 2W of power, then 2W of power is discarded for no reason every hour, which is also a waste.

maychang

sky999 posted on 2020-6-16 02:15 Um, I have never used a transformer. Does 2mA mean 220V2mA? Or does it mean the 2mA voltage converted by the transformer?

This kind of transformer has 2mA in both primary and secondary.

What I said on the second floor was: Don't use this kind of transformer, it doesn't save electricity.

maychang

sky999 posted on 2020-6-16 02:15 How to use capacitors to reduce voltage? It is best to use smaller ones

Didn't you use an optocoupler? You use 1mA current to supply the optocoupler. If it's 5V, connect a 3.9k resistor in series. If it's 220V, connect a 220k resistor in series...

Now change to connect a capacitor in series. If 1mA is still required, use a 15nF capacitor in series with the optocoupler, and a 1-2k resistor in series, and a rectifier diode in anti-parallel with the optocoupler.

In this method, the optocoupler works in pulse switching mode with a pulse frequency of 50Hz.

maychang

sky999 posted on 2020-6-16 02:21 Because the detection is maintained for a long time, if 1 channel detection consumes 0.2W of power, 10 channels consume 2W of power, then 2W of power is discarded every hour for no reason, which is also a waste...

"Watt" is a unit of power. You can't say "2W of electricity is thrown away for no reason every hour", you can only say "2Wh (watt-hour) of electricity is thrown away for no reason every hour".

"Watt-hour" is the unit of energy, which is 3600 joules.

qwqwqw2088

How to solve the problem of power supply for microcontroller circuit?

仙猫

sky999 posted on 2020-6-16 02:21 Because the detection is maintained for a long time, if 1 channel detection consumes 0.2W of power, 10 channels consume 2W of power, then 2W of power is discarded every hour for no reason, which is also a waste...

It is not necessary to [maintain] the detection for a long time, and intermittent detection can also be performed. It is just a matter of comprehensively weighing whether adding components or consuming more electricity is more cost-effective.

damiaa

Use manganese copper sheets. Ordinary household single-phase electric meters use manganese copper sheets for detection. Three-phase electric meters also use mutual inductors.

chunyang

sky999 posted on 2020-6-16 02:19 For home appliances, either the detection components or the microcontroller IO port detects whether there is 220V input externally

The detection element refers to the element in the circuit that is ultimately used to determine whether there is AC input. Obviously, in your application, it is the MCU, and in the home appliance, it is the application. But the amount of information in your sentence is still insufficient, so we have to guess.

If the internal circuit design is a thermal ground, a high-resistance resistor can be connected in series between the IO and the live wire. This is the cheapest solution. The principle is to use the IO clamp inside the MCU to obtain an approximate square wave on the IO, and then the software can make a judgment. This method requires strict control of the peak value of the clamping current, and the resistance value of the current limiting resistor must be calculated. For high-reliability design, an external clamping diode (the threshold must be lower than the built-in clamp) and a rectification method can be used. For non-thermal ground design, an optocoupler should be used for detection. The current is limited, and it is not detected as zero crossing. Only the peak value is considered. The output is a narrow pulse. The narrower the pulse, the lower the power consumption.

chunyang

If your system is not powered by batteries or an external power adapter, another method is to collect data on the power supply, but the specific method depends on what power supply you use and the specific design.

The information provided by the OP is too little, so we can only guess, and the solution can only be universal. The optimal solution must consider the specific application and its design.