Bidirectional DC/DC converter and method for charging the intermediate circuit capacitor of a DC/DC converter from the low-voltage battery

摘要

The invention relates to a bidirectional DC/DC converter for transmitting energy between a high-voltage grid (HV) and a low-voltage grid (LV), comprising connections for a high-voltage battery (UHV) and a low-voltage battery (UNV). The converter comprises the following:—one or more transformers (1) for galvanically isolating the low-voltage grid (LV) from the high-voltage grid (HV), an intermediate circuit capacitor (CZK) in the high-voltage grid (HV),—electronic switches (D1 to D4, M1 to M4) for connecting and reversing the polarity of the coil of the transformer (1) on the high-voltage grid (HV) and on the low-voltage grid (LV),—a controller (2) for controlling the electronic switches (D1 to D4),—and a series inductance (W1) in the low-voltage grid (NV). The series inductance (W1) is designed as a discharge transformer (3) for discharging the energy stored in the series inductance (W1), wherein a second coil (W2) is connected in series to a discharge switch (S) and a diode (D), and the series inductance (W1) is discharged to the low-voltage battery (UNV) when the discharge switch (S) is activated. The invention additionally relates to a method for charging the intermediate circuit capacitor (CZK) of the converter to the high-voltage grid potential from the low-voltage battery (UNV).