Road vehicle provided with an electronic DC-DC power converter and corresponding control method

A road vehicle (1) comprising:

• an internal combustion engine (5);
• an electric starter motor (20), which is coupled to the internal combustion engine (5) and can be operated to start the internal combustion engine (5);
• a high-voltage electric circuit (16) provided with a first storage system (14);
• a low-voltage electric circuit (17) provided with a second storage system (24), which has the same nominal voltage as the electric starter motor (20) and is directly connected to the electric starter motor (20) to directly supply power to the electric starter motor (20) without the interposition of any conversion device;
• an electronic DC-DC power converter (23), which connects the low-voltage electric circuit (17) and the high-voltage electric circuit (16) to one another to transfer power from the high-voltage electric circuit (16) to the low-voltage electric circuit (17);
• and
• a control unit (26) configured to:
• detect a turned-on condition of the road vehicle (1) when a driver turns on the road vehicle (1), thus making the road vehicle (1) ready for the start of the internal combustion engine (5), by turning an ignition key or by pressing a start button;
• detect a cold-start condition of the internal combustion engine (5) when a temperaure of a cooling liquid in the internal combusion engine is below a predetermined threshold;
• and
• transfer power from the high-voltage electric circuit (16) to the low-voltage electric circuit (17) using the electronic DC-DC power converter (23) and from the low-voltage electric circuit (17) to the electric starter motor (20) upon detection of the turned-on condition of the road vehicle (1) when the internal combustion engine (5) is off and when the cold-start condition of the internal combustion engine (5) is detected;
• wherein, when the cooling liquid in the internal combusions engine is greater than the predetermined threhold value, the cold-start condition of the internal combustion engine (5) is not detected, and the power to be supplied to the electric starter motor (20) is exclusively provided by the second storage system (24);
• wherein the control unit (26) is configured to activate the electronic DC-DC power converter (23) prior to cranking of the internal combustion engine when the cold-start condition of the internal combustion engine (5) is detected, as soon as the turned-on condition of the road vehicle (1) is detected so that the electronic DC-DC power converter (23) supplies electrical power to the low-voltage electric circuit (17) even before the electric starter motor (20) starts to absorb electrical power;
• and
• wherein the control unit (26) is configured to deactivate the electronic DC-DC power converter (23) after a predetermined amount of time has elapsed since the road vehicle (1) was turned on and the electronic DC-DC power converter (23) was activated without requests for a start of the internal combustion engine (5).