# Converting 100V DC into 150V DC low current <2ma.

#### Peterperkins

Joined Nov 5, 2018
19
Looking for ideas on a circuit to follow a HV battery voltage range from 90-130V DC and produce input voltage +50%

100V DC would become 150V DC
90V DC would become 135V DC
130V DC would become 195V DC

The output current requirements are very modest <2ma but it must track the input voltage and increase it by 50%
It will be feeding into an approx 100K minimum load..

Ideas?

I looked at doublers/multipliers but they require an AC or chopped input.
That might be doable if the output voltage can be controlled accurately enough by varying the pwm etc.

It's possible to buy a commercial unit see link but it looks expensive and tricky to get.

https://www.picoelectronics.com/node/69108

#### wayneh

Joined Sep 9, 2010
16,384
My approach would be to chop the input voltage and feed that to a transformer. Rectify and filter the output, and you’ll have potentially plenty of current. The output will follow the input and the only challenge is selecting the right transformer ratio. Just do the math.

#### Peterperkins

Joined Nov 5, 2018
19
Thanks. Finding a suitable transformer seems tough. My nomenclature might not be right when searching.
I'm looking for a 2-1 turns ratio with 100V input and 150v output capability.

Anyone any other ideas.

How about a high voltage op amp LTC6090 generating it's own sine wave and feeding into the simple capacitor doubler?

#### jpanhalt

Joined Jan 18, 2008
9,130
If you gave some idea of why you want to do that, there might be other approaches. For example, level shifters effectively convert a DC signal at one voltage, say 3.3 V, to another voltage, such as 5 V.

Of course, you need the higher voltage available. In context, if you have a 150 V DC source, you could have it mimic the 100 V source.

#### Peterperkins

Joined Nov 5, 2018
19
I have a variable dc voltage source an HV battery which varies between 90-130V.
I need to add 50% to that voltage to feed a high impedance HV detection circuit.

Modifying the HV detection circuit so it reads 50% higher isn't possible due to encapsulation.

#### jpanhalt

Joined Jan 18, 2008
9,130
1) Does it need to be analog? That is, you refer to being 50% higher. Does that mean that the 90 V goes to 135 V, 92 V to 138 V and so forth? Or is it simply detecting the presence of 90 V or more?

2) Would something that took your "inputs" (90 V, 100 V, 130 V) and converted each to 195 V out be OK. A level shifter may do what you want, but for each voltage output, you will need a source for that voltage. Thus, it would be simpler, if each input could be converted to the same higher voltage.

#### Peterperkins

Joined Nov 5, 2018
19
Yes it needs to be analog and eventually 50% higher than the input voltage. It has to track the input.

It could be 100% higher as I could then use a potential divider to get it down to the 50% I need.

#### Kjeldgaard

Joined Apr 7, 2016
398
I'm still missing a detailed description of what the 150 Volts should be used for, and thus how stable and noise-free it is needed.

But when I saw the headline, I came to think of some Nixie supply from eBay. They are typically from 12 VDC to a adjustable 170 VDC and without galvanic separation.

#### jpanhalt

Joined Jan 18, 2008
9,130
With DC, I can think of 3 ways to increase it:
1) Level shifting (e.g., diode switching);
2) An op-amp amplifier; and
3) Chopping it and using some sort of multiplier like capacitor switching or transformer.*

Only the last method increases the voltage without needing a high voltage available. The first method is usually digital. Methods 2 and 3 can be analog. If you have a high voltage available (higher than your highest voltage), you might consider a high voltage op-amp solution:

Source: http://www.ti.com/ww/en/bobpease/assets/AN-31.pdf

High-voltage op-amps:
https://www.digikey.com/products/en/integrated-circuits-ics/linear-amplifiers-instrumentation-op-amps-buffer-amps/687?k=op-amp&k=&pkeyword=op-amp&sv=0&pv659=1381&pv659=2620&pv659=2621&pv659=2816&pv659=143822&pv659=143823&pv659=143825&pv659=143832&pv659=184608&pv659=184609&pv659=184610&pv659=184611&pv659=184614&pv659=215315&pv659=238748&pv659=257654&pv659=261832&pv659=287651&pv659=287652&pv659=69642&pv659=69643&pv659=69645&pv659=69647&pv659=94761&pv659=100675&sf=1&FV=-8|687&quantity=&ColumnSort=0&page=1&pageSize=25

*Edit: or motor.

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#### Janis59

Joined Aug 21, 2017
1,169
Why not the boost-up SMPS?? For example MC34063 like in datasheet, only MUST be insulated (boosted) the Vcc input and output with proper resistive divider (input) and booster transistor bucket (output).

#### Janis59

Joined Aug 21, 2017
1,169
By the way, laughful solution but who knows? Simply obtain from the Mains a certain 50 V galvanically insulated voltage source and switch it in series with Your battery.

#### Peterperkins

Joined Nov 5, 2018
19
Sorry this is a mobile hybrid car solution so mains isn't an option.

The HV is used by a car systems to detect the HV battery voltage.
I want to fool the car into thinking a lower voltage battery is in the normal operating range.

So I want a 100V battery to appear to be a 150V battery to the car voltage detection systems. +50%
It uses high impedance voltage detection circuits, so our fake voltage needs a minimal <2ma current capability.

#### jpanhalt

Joined Jan 18, 2008
9,130
From a BMS (battery management) standpoint, I don't think that is particularly safe to do. Doesn't the car have a "limp home" mode?

In any event, any method of upping the voltage (chopper --> increase --> rectifier/low-pass filter) should work.

With such low current drain, you could have a small standby battery with high voltage or use just one low-current HV supply for multiplying to the highest needed voltage. Then use the op-amp solution. The op-amp solution gives you a fixed amplification factor.

#### Peterperkins

Joined Nov 5, 2018
19
Thanks for the thoughts but it's not about limping home etc and abusing a standard battery.

It's about running the system with a lower voltage bespoke battery.

I'll be closely managing the new pack.

I just want fake voltages (New battery voltage + 50%) to keep the car happy. Thanks

#### wayneh

Joined Sep 9, 2010
16,384
With the availability of a high voltage op-amp, I'd build a simple voltage doubler. Here's one I used to double a 12v supply up to over 20v. Worked great.