直流驱动器回升电路计算方式

For example if the Main DC voltage = 400Vdc and you want to set the Shunt Voltage at 390Vdc than

390*R38/(R38+Rtotal) = 3V

for simplicity we can say that Rtotal = R31+R32

setting R38=10K ohm

than 390*10K/(10K+Rtotal) = 3V

results in Rtotal =1.29MOhm

Rtotal /2 = R31 = R32 = 645K Ohm

if you want smaller resistors than you can devide Rtotal/4 or Rtotal/5 …

R38 should be around few K ohms, namely ~6K-20Kohm