Electrical system for a motor vehicle

An electric system for a motor vehicle, the vehicle comprising at least one power supply battery, the electric system comprising an electric charger intended to be connected, both to said battery and also to an electric network outside the vehicle supplying an AC voltage or to electric equipment, and a microcontroller, the charger being able to charge the battery from an external electric network or to allow the battery to power said equipment, the charger comprising:

• a) a power factor corrector circuit able to convert an AC voltage into a DC voltage;
• b) a DC-DC voltage converter connected between the power factor corrector circuit and the battery and able to convert a DC voltage into another DC voltage, said DC-DC voltage converter comprising a first H-bridge, and a second H-bridge, each H-bridge comprising four switches, a first switch being connected between a high point and a midpoint, a second switch being connected between the midpoint and a low point, a third switch being connected between the high point and a second midpoint and a fourth switch being connected between the second midpoint and the low point, the voltage converter also comprising a transformer electrically connecting the first H-bridge and the second H-bridge, each H-bridge being able to operate in:
• i. a first operating mode, in which the first switch and the fourth switch are open and closed simultaneously, the second switch and the third switch are open and closed simultaneously in contrast to the first switch and the fourth switch;
• ii. a second operating mode, in which the fourth switch is always closed, the third switch is always open, and the first switch and the second switch are alternately open and closed;
• the microcontroller is configured for:
• 1. commanding the opening and closing of each switch of the first bridge and of the second bridge of the DC-DC voltage converter by transmitting a command signal to each switch that is characterized by a frequency, with the high state of the command signal for commanding the closure of a switch and the low state of the command signal for commanding the opening of a switch;
• 2. when the microcontroller receives a request to transition from the first operating mode to the second operating mode for the first bridge, respectively the second bridge:
• i. transmitting a command to close the fourth switch and a command to open the third switch of the first bridge, respectively of the second bridge;
• ii. setting the frequency of the command signal transmitted to the first switch and to the second switch of the first bridge, respectively of the second bridge, to a first predefined maximum frequency value for a predetermined duration;
• iii. when the predetermined duration has elapsed, deactivating the second active operating mode and activating the first operating mode of the first bridge, respectively of the second bridge;
• 3. when the microcontroller receives a request to transition from the second operating mode to the first operating mode for the first bridge, respectively the second bridge:
• i. setting the frequency of the command signal transmitted to each switch of the first bridge, respectively of the second bridge, to a second predefined maximum frequency value for a predetermined duration;
• ii. when the predetermined duration has elapsed, deactivating the first active operating mode and activating the second operating mode of the first bridge, respectively of the second bridge.