Comments on High Power Switch - High Side vs. Low Side Switching
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High Power Switch - High Side vs. Low Side Switching
Imagine a battery pack with <=60VDC of maximum voltage and a load of up to 10kW of power(the PMSM inverter with the input capacitance of up to 1mF). The load is not always known - could be 100uF-1000uF input capacitance while the currents usually range from 20A up until 150A. The load is switched on/off using N channel Mosfets. Since there is no galvanic isolation present in the system peripheral communication interfaces(i.e. RS485/CAN) share the same GND as the load.
Approach 1)
Approach 2)
Note: Precharge circuit is present but omitted from the schematic
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Is there a superior architecture approach in this case?
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Could "Approach 2)" harm any of the components due to the ground reference loss?
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Answer to question 1: First, you need p-mos and not n-mos, as you are switching the circuit from the above. Second, it is better and simpler to parallelize mosfets for big current switches; this will reduce the power dissipation as well.
So, even if there exist a pmos with 150A ability (which I'm not sure), it is probably better and less expensive to parallelize 3 p-mos (say) of 60A. The NVD5117PL 60V, 60A, is an option. Here is the schematic:
And here is a solution if you have to control the switch from below:
Answer to question 2: There is apparently no problem with your second approach, but we don't know the whole story: is there anything else connected to the battery? we need to know the whole circuitry to answer to this question. Also, you may connect the ground after the mosfet switch, if the battery is floating. Finally, are you sure you know how to connect mosfets in series to distribute the power? this is not as trivial as parallelizing them for a switch!
Note: Again, I would implement 2 or 3 n-mos in parallel, in place of 2 n-mos in series.
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