Lithium battery for a PHEV?

[mading2018]

Hmm, I see. But do you how to obtain for an example a current rate of 4 A? Can you maybe show me how, so it makes more clearer for me.

 

[ChrisP58]

Hmm, I see. But do you how to obtain for an example a current rate of 4 A? Can you maybe show me how, so it makes more clearer for me.

4 amps where? At the output? That is limited by your load resistor. Use Ohms law to calculate a load resistance that will draw the desired current when placed across the output voltage of the PFC boost converter.

Notes:
1) Since the output voltage has a fair amount of ripple, the output current will vary by the same degree.
2) If the output voltage is lower than what it has been, you may be pushing the limits of other components in the circuit. If so, you may need to adjust values of R6 and/or L1.

 

[mading2018]

I wish to have a 4 A input from the AC grid. But what I understand a load resistor at the input won't change anything.
The load resistor at the output must be changed in order to get 4 Amps input, right? Correct me if I am wrong.

Okay, I will note that.

 

[ChrisP58]

You have no direct control over the magnitude of the input current. The input will draw whatever current it needs to in order to get it's work done. The PFC control circuits job is just to control the shape if the current waveform. To make it look sinusoidal and in phase with the input voltage.

You do have control of the work that the PFC boost converter is doing. As such, you have indirect control of the input current, by adjusting the output current.

But I'm curious. Why do you need the input current to be 4 amps?

 

[mading2018]

Yes, thats true. So in other words, it is impossible for me to adjust the input current?

I want to have 4 Amps, because for the power outlet here in Europe, they are only designed for draw a current maximum of 10 A before it is getting too hot, so my task is to use a lower current, for an instance, 4 A (or 6 A or 8 A). This AC/DC converter is part of a low-power charger for an electric vehicle.

 

[ChrisP58]

Then you need something that measures the input current, compares it to the desired value, then adjusts the output power up or down to keep the input current where you want it to be.

 

[mading2018]

Is it some kind of feedback that is needed? Could someone please show me how it could be implemented in my file, I am not sure how to do it. Thank you.

 

[alec_t]

R6 and the Mout pin of the IC are responsible for current monitoring and hence control. I don't see how, with that IC, you can superimpose some current limiting in addition without compromising the PFC function. Perhaps Chris can?

 

[ChrisP58]

Since the PFC circuit is only the front end of your battery charger, there's no reason to try to implement the limiting at this point. The place to do so is in the final output of the battery charger.

Things to consider:
- Input current should be measured and integrated over at least one full AC period, probably more than one.
- Some form of loop compensation will be needed to prevent oscillation.
- A battery being charged is not a constant load, but varies depending on state of charge.

 

[mading2018]

Any simulation makes certain assumptions. Keep reminding yourself that a simulation is only an approximation of real life,

About the calculated values compared to the simulations values, is it okay if the losses are not exactly correct? I mean if got total losses of 35 W, but the calculated values is 23 W. Is it okay do assume it worked? I mean it is after all a simulation.

 

[alec_t]

About the calculated values compared to the simulations values, is it okay if the losses are not exactly correct?

Simulation values are calculated values. Obviously you're not calculating them the same way that LTS does .

 

[mading2018]

Simulation values are calculated values.

Haha, yeah, thats true. but I meant my hand calculations. So would it be a bad idea to compare them? Cause SPICE gives only an approximation?

--edit--
I tried to increase efficiency for the boost, but I can't do it with the give values... so that's why I was asking about the hand calculated and simulations values should be corresponding to each other. According to the theory, the efficiency should be about 95 % for a boost PFC. and I only got 92 %.

 

[alec_t]

So would it be a bad idea to compare them?

Yes, if you aren't using the same calculation algorithm as LTS, or are calculating over a different time interval.

According to the theory

Which theory?