Variable DC link converter and transformer for wide output voltage range applications
A variable direct current (DC) link power converter is described. In one example, the power converter includes a first converter stage configured to convert power from a power source to power at an intermediate link voltage and a second converter stage configured to convert the power at the intermediate link voltage to power for charging a battery. The power converter further includes a control system having an intermediate link voltage regulation control loop configured, in a first mode of operation, to regulate the intermediate link voltage through the first converter stage based on a voltage of the battery, and a ripple regulation control loop configured to sense a charging current for the battery and regulate a gain of the second converter stage based on the charging current to reduce ripple in the charging current. A new configuration of transformer suitable for use with the power converter is also described.
1. A power converter, comprising:
a first converter stage configured to convert power from a power source to power at an intermediate link voltage;
a second converter stage configured to convert the power at the intermediate link voltage to power for charging a battery; and
a control system comprising:
an intermediate link voltage regulation control loop configured, in a first mode of operation, to regulate the intermediate link voltage through the first converter stage based on a voltage of the battery; and
a ripple regulation control loop configured to sense a charging current for the battery and regulate a gain of the second converter stage based on the charging current to reduce ripple in the charging current.
2. The power converter of claim 1 , wherein the first converter stage comprises an alternating current (AC) to direct current (DC) converter stage, and the second converter stage comprises a DC to DC converter stage.
3. The power converter of claim 1 , wherein the ripple regulation control loop is configured to regulate at least one of a switching frequency, phase shift angle, or duty cycle of switching transistors in second converter stage.
4. The power converter of claim 1 , wherein the intermediate link voltage regulation control loop configured, in a second mode of operation, to regulate the intermediate link voltage through the second converter stage based on the voltage of the battery.
5. The power converter of claim 4 , wherein the battery is charging in the first mode and discharging in the second mode.
6. The power converter of claim 1 , wherein the control system further comprises a critical conduction mode (CRM) power factor correction (PFC) control loop.
7. The power converter of claim 1 , wherein the control system further comprises a charging profile control loop configured to provide a current reference input to the ripple regulation control loop based on a charging profile for the battery.
8. The power converter of claim 7 , wherein the charging profile for the battery comprises pre-charge, constant current charge, constant power charge, and constant voltage charge stages.
9. The power converter of claim 1 , wherein:
the second converter stage comprises a transformer, the transformer comprising an E-shaped core having an inner post and outer posts, an I-shaped core, a primary winding, and a secondary winding; and
the primary winding and the secondary winding are interleaved among each other on the outer posts of the E-shaped core.
10. The power converter of claim 9 , wherein a number of windings of the primary winding on a first of the outer posts of the E-shaped core is different than a number of windings of the primary winding on a second of the outer posts of the E-shaped core.
11. The power converter of claim 9 , wherein an air gap between the I-shaped core and the inner post of the E-shaped core is selected to determine a leakage of the transformer.
12. A power converter, comprising:
a first converter stage and a second converter stage configured to convert power using an intermediate link voltage; and
a control system comprising:
an intermediate link voltage regulation control loop configured to regulate the intermediate link voltage through at least one of the first converter stage or the second converter stage; and
a ripple regulation control loop configured to regulate a gain of the first converter stage or the second converter stage to reduce ripple in current output by the power converter.
13. The power converter of claim 12 , wherein the first converter stage comprises an alternating current (AC) to direct current (DC) converter stage, and the second converter stage comprises a DC to DC converter stage.
14. The power converter of claim 12 , wherein the control system further comprises a critical conduction mode (CRM) power factor correction (PFC) control loop.
15. The power converter of claim 12 , wherein the control system further comprises a charging profile control loop configured to provide a current reference input to the ripple regulation control loop based on a charging profile for a battery.
16. The power converter of claim 15 , wherein the charging profile for the battery comprises pre-charge, constant current charge, constant power charge, and constant voltage charge stages.
17. The power converter of claim 12 , wherein:
at least one of the first converter stage or the second converter stage comprises a transformer, the transformer comprising an E-shaped core having an inner post and outer posts, an I-shaped core, a primary winding, and a secondary winding; and
the primary winding and the secondary winding are interleaved among each other on the outer posts of the E-shaped core.
18. The power converter of claim 17 , wherein a number of windings of the primary winding on a first of the outer posts of the E-shaped core is different than a number of windings of the primary winding on a second of the outer posts of the E-shaped core.
19. The power converter of claim 18 , wherein an air gap between the I-shaped core and the inner post of the E-shaped core is selected to determine a leakage of the transformer.