Method for controlling a high-pressure fuel injector

A method for controlling a high-pressure fuel injector for an internal combustion engine of a motor vehicle, the fuel injector being provided with a solenoid configured to actuate a needle which opens the injector and a spring configured to return said needle to a closed position, the solenoid of the fuel injector being supplied with a current by a control circuit including a first voltage source, a second voltage source, a first transistor, a second transistor, a third transistor, a first diode, a second diode, and a third diode, a drain of the first transistor connected to the first voltage source, a source of the first transistor being connected to an anode of the first diode, a cathode of the first diode being connected to:

• (i) a cathode of a second diode, (ii) a first connector of the solenoid of the injector, and (iii) a source of the second transistor, a drain of the second transistor being connected to the second voltage source, an anode of the second diode being connected to ground, the second voltage source being connected to:
• (i) ground via a capacitance, (ii) a cathode of the third diode, and (iii) the drain of the second transistor, an anode of the third diode being connected to a second connector of the solenoid of the injector and to a drain of a third transistor, a source of the third transistor being connected to ground via a resistor, the control method comprising:
• measuring a voltage of the second voltage source;
• determining whether the measured voltage of the second voltage source is lower than a voltage threshold allowing the current to open the needle of the fuel injector;
• when the measured voltage of the second voltage source is determined to be lower than the voltage threshold, determining whether the injection is not required;
• when the injection is not required,
• in a first state, charging the solenoid of the injector by controlling the first transistor and the third transistor to be on while controlling the second transistor to be off, and
• in a second state, after detecting an inductance charging current greater than a reference current through the resistor, controlling the first transistor to be on while the second transistor and the third transistor are controlled to be off;
• waiting a predetermined time to allow the solenoid to discharge;
• determining whether the voltage of the second voltage source is lower than the voltage threshold allowing the current to open the needle of the fuel injector;
• and
• when the voltage of the second voltage source is lower than the voltage threshold, returning to charging the solenoid of the fuel injector.