Constant current to constant voltage dual active bridge LCL-transformer resonant DC-DC converter

A power converter comprising:

• a primary H-bridge comprising a first semi-conductor switch, a second semi-conductor switch, a third semi-conductor switch, and a fourth semi-conductor switch, wherein the first semi-conductor switch and the second semi-conductor switch are in leg A with terminal A between the first semi-conductor switch and the second semi-conductor switch in leg A and the third semi-conductor switch and the fourth semi-conductor switch are in leg B with terminal B between the third semi-conductor switch and the fourth semi-conductor switch in leg B, said terminal A and said terminal B forming an output of the primary H-bridge;
• an LCL-Transformer section comprising a first inductor Lr with a first end connected to said terminal A, a capacitor Cr connected between a second end of the first inductor Lr and said terminal B, and a second inductor Lg with a first end connected to the second end of the first inductor Lr;
• a transformer with a primary side connected between a second end of the second inductor Lg and said terminal B, the transformer comprising a turns ratio n;
• a secondary H-bridge comprising a fifth semi-conductor switch, a sixth semi-conductor switch, a seventh semi-conductor switch, and an eight semi-conductor switch with an input connected to a secondary side of the transformer, wherein the fifth and sixth semi-conductor switches are in leg D with terminal D between the fifth and sixth semi-conductor switches of leg D and the seventh and eighth semi-conductor switches are in leg E with terminal E between the seventh and eighth semi-conductor switches of leg E, said terminal D and said terminal E forming an output of the secondary H -bridge;
• and
• an output capacitor Cf connected across said terminal D and said terminal E,
• wherein the primary H-bridge is fed by a direct current (DC) constant current source, and wherein said terminals D and E are connected to a load and an output voltage across said terminals D and E is regulated to maintain a constant DC output voltage, and
• wherein:
• the first, second, third and fourth semi-conductor switches of the primary H-bridge are operated with the symmetrical phase shift modulation with leg A leading leg B by an angle φAB;
• the fifth, sixth, seventh, and eighth semi-conductor switches of the secondary H-bridge are operated with the symmetrical phase shift modulation with leg D leading leg E by an angle φDE;
• an angle between leg A and leg D is angle φAD;
• and
• the output voltage of the secondary H-bridge is maintained at a constant voltage by controlling angle φAB, angle φDE, and angle φAD,
• wherein a relationship between angle φAB, angle φDE, and angle φAD is:
• φ
• A
• ⁢
• D
• =
• φ
• A
• ⁢
• B
• 2
• +
• π
• 2
• -
• φ
• D
• ⁢
• E
• 2
• .

A bidirectional power converter comprising:

• a primary H-bridge comprising a first semi-conductor switch, a second semi-conductor switch, a third semi-conductor switch, and a fourth semi-conductor switch, wherein the first semi-conductor switch and the second semi-conductor switch are in leg A with terminal A between the first semi-conductor switch and the second semi-conductor switch in leg A and the third semi-conductor switch and the fourth semi-conductor switch are in leg B with terminal B between the third semi-conductor switch and the fourth semi-conductor switch in leg B, said terminal A and said terminal B forming an output of the primary H-bridge;
• an LCL-Transformer section comprising a first inductor Lr with a first end connected to terminal A, a capacitor Cr connected between a second end of the first inductor Lr and said terminal B, and a second inductor Lg with a first end connected to the second end of the first inductor Lr;
• a transformer with a primary side connected between a second end of the second inductor Lg and said terminal B, the transformer comprising a turns ratio n;
• a secondary H-bridge comprising a fifth semi-conductor switch, a sixth semi-conductor switch, a seventh semi-conductor switch, and an eight semi-conductor switch with an input connected to a secondary side of the transformer, wherein the fifth and sixth semi-conductor switches are in leg D with terminal D between the fifth and sixth semi-conductor switches of leg D and the seventh and eighth semi-conductor switches are in leg E with terminal E between the seventh and eighth semi-conductor switches of leg E, terminal D and terminal E forming an output of the secondary H-bridge;
• and
• an output capacitor Cf connected across said terminal D and said terminal E,
• wherein the primary H-bridge is fed by a direct current (DC) constant current source, and wherein said terminals D and E are connected to a load and an output voltage across said terminals D and E is regulated to maintain a constant DC output voltage,
• wherein:
• the first, second, third and fourth semi-conductor switches of the primary H-bridge are operated with symmetrical phase shift modulation with leg A leading leg B by an angle conductor φAB;
• the fifth, sixth, seventh, and eighth semi-conductor switches of the secondary H-bridge are operated with symmetrical phase shift modulation with leg D leading leg E by an angle φDE;
• an angle between leg A and leg D is angle φAD;
• and
• a power flow direction from the primary H-bridge to the secondary H-bridge is dependent on a phase angle φPS, which is:
• φ
• P
• ⁢
• S
• =
• φ
• A
• ⁢
• D
• -
• φ
• A
• ⁢
• B
• 2
• +
• φ
• D
• ⁢
• E
• 2
• .