Any high-voltage bus needs to have a precharge circuit to reduce the current flow over a period of time, called the dv/dt, to protect the electronic devices in a battery electric vehicle. The challenge with a traditional solution to this age-long problem is that the precharge resistor charge time is inversely proportional to the power dissipation.

A better approach is taking the power components in the battery electric vehicle and reusing them to charge the high voltage bus from a low-voltage source. Using power modules the regulator can be used in reverse, regulating the voltage and current.