Method for controlling a DC-DC converter for a two-way electrical storage battery charger

1. A method for controlling a frequency of an input voltage of a DC-to-DC converter of a bidirectional electrical charger that is connected to a battery, operating in battery-discharging mode with a duty cycle of 50%, said method comprising:

defining a setpoint input voltage value at an input of the DC-to-DC converter, inputs and outputs of the DC-to-DC converter being defined with respect to a battery-charging mode;

calculating a control frequency value for said DC-to-DC converter, said control frequency value being obtained by inverting a gain of said DC-to-DC converter, according to an output battery voltage, an input power setpoint, and said setpoint input voltage value; and

applying the control frequency value to said DC-to-DC converter.

2. The method as claimed in claim 1 , wherein said DC-to-DC converter is of a series LLC resonant type comprising, at the input, a full switching bridge that is connected to an LLC resonant circuit that is connected to a transformer that is connected to the battery via an H-bridge, said LLC resonant circuit comprising a series inductor, a switched inductor that is connected to output terminals of said full switching bridge only in a discharging mode, and a series capacitor, and

wherein said control frequency value is dependent on said series inductor, said switched inductor, and said series capacitor.

3. The method as claimed in claim 1 , wherein the applying the control frequency value comprises:

defining a frequency increment step;

initializing the control frequency value at an initial control value corresponding to the control frequency value that is calculated;

defining a first threshold value and a second threshold value, an opposite value to the first threshold value and an opposite value to the second threshold value, the first threshold value being strictly greater than the second threshold value and said first and second threshold values being strictly positive;

calculating an error value between a measured input voltage value and said setpoint input voltage value; and

comparing said error value and said first threshold value, said second threshold value, the opposite value to the first threshold value, and the opposite value to the second threshold value;

wherein the method further comprises regulating in which:

when said error value is between the first threshold value and the opposite value to the first threshold value, and when said error value is greater than the second threshold value or less than the opposite value to the second threshold value, the control frequency value is incremented or decremented by the frequency increment step;

when said error value is between the second threshold value and the opposite value to the second threshold value, the control frequency value is maintained at a previous value; and

when said error value is greater than the first threshold value or when said error value is less than the opposite value to the first threshold value, the initial control value is applied as the control frequency value.

4. The method as claimed in claim 1 , further comprising feedback regulation of the control frequency value.

5. The method as claimed in claim 1 , wherein, as soon as the control frequency value reaches a value approaching 200 kHz and a measured input voltage departs from the setpoint input voltage value, a packet regulating mode is activated including applying a maximum frequency while at a same time stopping chopping at intervals in order to let the input voltage return to the setpoint input voltage value.

6. A bidirectional charger for charging electrical accumulators, comprising:

a power-factor correction stage;

at least one DC-to-DC converter; and

a device configured to control a frequency of an input voltage of the at least one DC-to-DC converter of the bidirectional charger that is connected to a battery, operating in a battery-discharging mode with a duty cycle of 50%, the device being configured to

define a setpoint input voltage value at an input of the at least one DC-to-DC converter, inputs and outputs of the at least one DC-to-DC converter being defined with respect to a battery-charging mode,

calculate a control frequency value for the at least one DC-to-DC converter, the control frequency value being obtained by inverting a gain of the at least one DC-to-DC converter, according to an output battery voltage, an input power setpoint, and the setpoint input voltage value, and

apply the control frequency value to the at least one DC-to-DC converter.

7. A motor vehicle comprising:

the bidirectional charger for charging electrical accumulators as claimed in claim 6 .

8. A device for controlling a frequency of an input voltage of a DC-to-DC converter of a bidirectional electrical charger that is connected to a battery, operating in battery-discharging mode with a duty cycle of 50%, the device comprising:

circuitry configured to

define a setpoint input voltage value at an input of a DC-to-DC converter, inputs and outputs of the DC-to-DC converter being defined with respect to a battery-charging mode,

calculate a control frequency value for the DC-to-DC converter, the control frequency value being obtained by inverting a gain of the DC-to-DC converter, according to an output battery voltage, an input power setpoint, and the setpoint input voltage value, and

apply the control frequency value to the DC-to-DC converter.