Treating battery cells in a string as single cells in LTSpice?

Discussion in 'Power Electronics' started by hac LE, Jul 3, 2016.

  1. hac LE

    Thread Starter New Member

    Jul 3, 2016
    BMS scheme.jpg
    Hello all, I have a battery measurement circuit setup described in the image above. I want to use a boost converter to converter battery voltage to supply voltage for the measurement circuit. The boost converter should see each battery terminal as 0V and 12V not 0V+DC_OFFSET and 12V+DC_OFFSET. LTSpice requires a physical ground for an operable simulation so the battery terminal voltages are also referenced to this ground and I don't want that in my circuit. Is there any way to overcome this problem?
    Last edited: Jul 3, 2016
  2. crutschow


    Mar 14, 2008
    Yes, but that is a non-problem.

    Spice does require a ground so the simulator has a reference point for its calculations, but only one ground is needed in the circuit as long as every part of the circuit is connected to another part in the circuit.

    Any isolated circuit part does require it's own ground, but if you need to simulate a real isolated circuit, such as an opto isolator, then you can use a very large resistor to ground (many Giga ohms) from the isolated side of the circuit, which will make Spice happy.

    Thus, in your posted circuit you only need GND_4 for example (or wherever you want the single ground point), since everything else is tied together through other elements.
    In other words, all the elements have a path to ground, even if it's through another element.