Systems and methods for bridge mode transition and dynamic soft start for DC-DC converter and battery charger

1. A system for a direct current (DC)-DC converter, the system comprising:

a transformer;

a bridge driver connected to a primary side of the transformer, the bridge driver including one or more switches;

a bridge rectifier connected to a secondary side of the transformer; and

a controller configured to control the operation of the one or more switches based on a sensed voltage of a battery connected to the DC-DC converter and a power demand for the DC-DC converter,

wherein the one or more switches in the bridge driver are operable to configure the bridge driver into each of a half-bridge driver configuration and a full-bridge driver configuration,

wherein the controller is further configured to control the operation of the one or more switches to transition between the half-bridge driver configuration and the full-bridge driver configuration while the DC-DC converter is outputting power,

wherein the controller is further configured to ramp a current loop compensator output frequency lower limit from a maximum to a minimum with a predetermined soft start rate, and

wherein the controller is further configured to maintain a fixed duty cycle for the one or more switches with the predetermined soft start rate, and vary a switching frequency of the one or more switches with the predetermined soft start rate.

2. The system of claim 1 , wherein the power demand is a signal from a vehicle to the DC-DC converter.

3. The system of claim 1 , wherein the one or more switches include a first bridge driver switch and a second bridge driver switch on a first leg of the bridge driver, and a third bridge driver switch and a fourth bridge driver switch on a second leg of the bridge driver.

4. The system of claim 3 , wherein the controller is configured to control the operation of the one or more switches to configure the bridge driver into the half-bridge driver configuration by controlling the third bridge driver switch to be open and the fourth bridge driver switch to be closed.

5. The system of claim 1 , wherein the controller is further configured to control the operation of the one or more switches to configure the bridge driver in the half-bridge driver configuration when the sensed voltage of the battery connected to the DC-DC converter is in a low voltage region, to configure the bridge driver in either of the half-bridge driver configuration or the full-bridge driver configuration when the sensed voltage is in a nominal voltage region, and to configure the bridge driver in the full-bridge driver configuration when the sensed voltage is in a full voltage region.

6. The system of claim 5 , wherein the controller is further configured to, when the sensed voltage is in the nominal voltage region, check the power demand of the DC-DC converter, and

when the power demand is less than a minimum transition threshold, operating the bridge driver in the half-bridge driver configuration, and

when the power demand is more than the minimum transition threshold, operating the bridge driver in the full-bridge driver configuration.

7. The system of claim 1 , wherein the controller is further configured to vary the switching frequency of the predetermined soft start rate based on continuously comparing a current reference signal and a measured current.

8. The system of claim 1 , wherein the DC-DC converter has a voltage operating range from approximately 170V to approximately 850V at a battery interface connected to the bridge rectifier.

9. The system of claim 1 , further comprising an alternating current (AC) to direct current (DC) Power Factor Correction (PFC) converter connected to the bridge driver to provide the system as a battery charger.

10. The system of claim 9 , further comprising:

a battery connected to the DC-DC converter of the battery charger, and

a motor configured to rotate based on power received from the battery,

wherein the system is provided as a vehicle.

11. The system of claim 10 , wherein the battery charger is configured to:

receive input AC power through the PFC converter, convert the AC power to DC power, and provide the DC power to the battery to charge the battery, and

receive DC power from the battery through the DC-DC converter, convert the DC power to AC power, and provide the AC power through the PFC converter as output AC power.

12. The system of claim 1 , wherein the transformer includes a high-frequency transformer provided in a resonant tank.

13. A method for controlling a system including a direct current (DC)-DC converter including a transformer, a bridge driver connected to a primary side of the transformer, the bridge driver including one or more switches, and a bridge rectifier connected to a secondary side of the transformer, the method comprising performing, by a controller, operations including:

controlling the one or more switches in the bridge driver to configure the bridge driver into each of a half-bridge driver configuration and a full-bridge driver configuration based on a sensed voltage of a battery connected to the DC-DC converter and a power demand for the DC-DC converter, and to transition between the half-bridge driver configuration and the full-bridge driver configuration while the DC-DC converter is outputting power,

wherein the operations further include ramping a current loop compensator output frequency lower limit from a maximum to a minimum with a predetermined soft start rate, and

wherein the operations further include maintaining a fixed duty cycle for the one or more switches with the predetermined soft start rate, and varying a switching frequency of the one or more switches with the predetermined soft start rate.

14. The method of claim 13 , wherein the operations further include receiving the sensed voltage of the battery connected to the DC-DC converter, and

wherein the controlling the switching operation includes controlling the operation of the one or more switches to configure the bridge driver in the half-bridge driver configuration when the sensed voltage is in a low voltage region, to configure the bridge driver in either of the half-bridge driver configuration or the full-bridge driver configuration when the sensed voltage is in a nominal voltage region, and to configure the bridge driver in the full-bridge driver configuration when the sensed voltage is in a full voltage region.

15. The method of claim 13 , wherein the varying the switching frequency of the one or more switches of the predetermined soft start rate is based on continuously comparing of a current reference signal and a measured current.

16. A non-transitory computer readable medium storing instructions that, when executed by one or more processors, perform operations including:

controlling one or more switches in a bridge driver of a DC-DC converter to configure the bridge driver into each of a half-bridge driver configuration and a full-bridge driver configuration based on a sensed voltage of a battery connected to the DC-DC converter and a power demand for the DC-DC converter, and to transition between the half-bridge driver configuration and the full-bridge driver configuration while the DC-DC converter is outputting power,

wherein the operations further include ramping a current loop compensator output frequency lower limit from a maximum to a minimum with a predetermined soft start rate, and

wherein the operations further include maintaining a fixed duty cycle for the one or more switches with the predetermined soft start rate, and varying a switching frequency of the one or more switches with the predetermined soft start rate.