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Original question:

Need help to build DC power meter to measure energy up to 220V DC and 100A

Need help to build DC power meter to measure energy up to 220V DC and 100A_Few More queries

Satish Ghariya
Intellectual 390 points
Other Parts Discussed in Thread: TPS5410, REG113, LM5010

Hi,

This is with reference and related to query raised with Thread Title "Need help to build DC power meter to measure energy up to 220V DC and 100A".

1. Is it possible to build the low voltage (Say 3.3V or 5V or 12V) from the incoming DC. We can not provide separate DC supply to rest of the circuitry.

Let me know how it can be possible and any design Idea.  

This is with reference to design " http://www.ti.com/lit/ug/tidu849/tidu849.pdf "  you have shared earlier with me in other thread title for DC power measurement up to 440V DC

2. How can we reduce the board size and power dissipation when we take input 220V DC for building low voltage supply on board for driving rest of the circuitry

Thanks

  • 0
    TI__Mastermind 27600 points

    Hi,

    1 You can use a shunt regulator followed by a two stage DCDC to generate 12V and 5V respectively. Then you can use an LDO to generate the 3V. You’ll have to estimate current demand for each voltage and adjust the architecture, select components accordingly. I think it makes sense to have a high voltage shunt regulator, therefore DCDC #1 needs to be able to accommodate this high voltage input. Devices such as LM5016, LM5010 might be the right candidates. There is a great number of devices that can serve as 12V-5V, such as TPS5410. If you use a LDO for 5V-3.3V, there is an even bigger number of potential candidates, such as REG113.

    2 I would say start with tallying current demand for each voltage supply, and select power management IC accordingly. Also select passive components that are enough but not over-sized. These steps will help control the PCB space down the road. The last step is layout itself where you can try to use the area efficiently.

    Regards, Guang

  • 0 in reply to Guang Zhou
    Intellectual 390 points

    Thanks Guang,

     Just want to share again that we have DC input range up to 250V DC. So this is the input we have to down convert in two stage (first stage may be 48V DC or 24V DC) to use for low voltage like 3.3V/5V.

    We have to measure this 250V DC/100A for power measurement. I just wanted to use this 250V DC to use for driving other circuitry in system 

    As you have mentioned about shunt regulator, considering shunt regulator with the input 250V DC and regulated output of 48V DC or 24V DC ( zener of 48V DC or 24V DC) is very critical in terms of zener diode selection, power dissipation and maximum input voltage it can sustain .

    1. Let me know your opinion on this. 

    2. Is there any other way to achieve this DC-DC converter in 2 stage -3 stage or in single stage conversion from 250V DC Input.

    Thanks

  • 0 in reply to Satish Ghariya
    TI__Mastermind 27600 points

    Hi,

    1 You’re right the shunt regulator needs careful design, considering size, current capability and efficiency. The advantage is that it is simple and robust. You can have multiple Zeners in series. I think it makes sense in terms efficiency to have a higher voltage DCDC first stage.

    2 As far as I’m aware I don’t think there is an IC that can take 250V input. I suggest you post this query to the Power Management forum, where you’ll get true expert support.

    Regards, Guang