System and method for controlling current in a power converter

Patent metadata

Field	Value
Publication number	US-9780675-B2
Application number	US-201514965904-A
Country	US
Kind code	B2
Filing date	Dec 11, 2015
Priority date	Dec 11, 2015
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A power converter is presented. The power converter includes a primary bridge unit coupled to a voltage source. Further, the power converter includes a secondary bridge unit coupled to a load. Also, the power converter includes a transformer disposed between the primary bridge unit and the secondary bridge unit and configured to magnetically couple the primary bridge unit to the secondary bridge unit. Additionally, the power converter includes a current sensor configured to measure instantaneous current flowing at an input terminal of the transformer. Furthermore, the power converter includes a cyclic state controller configured to receive the measured instantaneous current flowing at the input terminal of the transformer, and change a switching state of the power converter from a present switching state to a subsequent switching state based on the measured instantaneous current.

First claim

The invention claimed is:

1. A power converter, comprising:
a primary bridge unit coupled to a voltage source;
a secondary bridge unit coupled to a load;
a transformer disposed between the primary bridge unit and the secondary bridge unit and configured to magnetically couple the primary bridge unit to the secondary bridge unit;
a current sensor configured to measure instantaneous current flowing at an input terminal of the transformer;
a cyclic state controller configured to:
receive the measured instantaneous current flowing at the input terminal of the transformer;
change a switching state of the power converter from a present switching state to a subsequent switching state based on the measured instantaneous current,
wherein to change the switching state of the power converter, the cyclic state controller is configured to follow a state machine comprising a plurality of switching states based on an electrical power desired at the load, wherein the plurality of switching states comprises at least the present switching state and the subsequent switching state, and wherein each of the plurality of switching states is associated with one of a first reference value, a second reference value, a third reference value, a fourth reference value, and a fifth reference value; and
restart the plurality of switching states after each fundamental cycle of the power converter.

2. The power converter of claim 1 , wherein the cyclic state controller is configured to change the switching state of the power converter to maintain the instantaneous current below a designed value.

3. The power converter of claim 1 , wherein the current sensor is electrically coupled to one of the input terminal and an output terminal of the transformer and configured to:
measure the instantaneous current flowing at one of the input terminal and the output terminal of the transformer; and
communicate the measured instantaneous current to the cyclic state controller.

4. The power converter of claim 3 , wherein the cyclic state controller is configured to:
sample the measured instantaneous current at a determined sampling rate;
compare the sampled instantaneous current with a reference value corresponding to the present switching state, wherein the reference value is one of the first reference value, the second reference value, the third reference value, the fourth reference value, and the fifth reference value based on the present switching state; and
change the switching state from the present switching state to the subsequent switching state based on the comparison.

5. The power converter of claim 1 , wherein the primary bridge unit comprises a plurality of electronic switches coupled to each other to form a primary H-bridge circuit, and wherein the secondary bridge unit comprises a plurality of electronic switches coupled to each other to form a secondary H-bridge circuit.

6. The power converter of claim 5 , wherein the transformer comprises:
a primary winding coupled to alternating current terminals of the primary H-bridge circuit; and
a secondary winding coupled to alternating current terminals of the secondary H-bridge circuit.

7. The power converter of claim 6 , wherein the cyclic state controller is configured to activate or deactivate at least one of the plurality of electronic switches in one of the primary H-bridge circuit and the secondary H-bridge circuit to change the switching state associated with the power converter.

8. The power converter of claim 1 , wherein the plurality of switching states comprises one or more sequential and non-overlapping states.

9. The power converter of claim 1 , wherein the cyclic state controller is configured to monitor the instantaneous current in real-time in each of the plurality of switching states.

10. A method, comprising:
measuring, by a current sensor, instantaneous current flowing at an input terminal of a transformer;
receiving, by a cyclic state controller, the measured instantaneous current flowing in the transformer;
changing, by the cyclic state controller, a switching state of a power converter from a present switching state to a subsequent switching state based on the measured instantaneous current, wherein changing the switching state of the power converter comprises following a state machine comprising a plurality of switching states based on an electrical power desired at a load, wherein the plurality of switching states comprises at least the present switching state and the subsequent switching state, and wherein each of the plurality of switching states is associated with one of a first reference value, a second reference value, a third reference value, a fourth reference value, and a fifth reference value; and
restarting, by the cyclic state controller, the plurality of switching states after each fundamental cycle of the power converter.

11. The method of claim 10 , wherein changing the switching state of the power converter comprises:
sampling the measured instantaneous current at a determined sampling rate;
comparing the sampled measured instantaneous current with a reference value corresponding to the present switching state, wherein the reference value is one of the first reference value, the second reference value, the third reference value, the fourth reference value, and the fifth reference value based on the present switching state; and
changing the switching state from the present switching state to the subsequent switching state based on the comparison.

12. The method of claim 11 , wherein changing the switching state associated with the power converter comprises activating or deactivating at least one of a plurality of electronic switches in the power converter to change the switching state associated with the power converter.

13. The method of claim 11 , wherein changing the switching state of the power converter comprises:
determining that the power converter is operating in the present switching state;
identifying the reference value corresponding to the present switching state; and
switching the power converter from the present switching state to the subsequent switching state based on a comparison of the measured instantaneous current with the reference value corresponding to the present switching state.

14. The method of claim 10 , further comprising monitoring the instantaneous current in real-time to maintain the instantaneous current below a designed value.

15. A power distribution system, comprising:
a voltage source;
an electric load;
a power converter disposed between the voltage source and the electric load, wherein the power converter comprises:
a primary bridge unit coupled to the voltage source;
a secondary bridge unit coupled to the electric load;
a transformer disposed between the primary bridge unit and the secondary bridge unit and configured to magnetically couple the primary bridge unit to the secondary bridge unit;
a current sensor configured to measure instantaneous current flowing at an input terminal of the transformer;
a cyclic state controller configured to:
receive the measured instantaneous current flowing at the input terminal of the transformer;
change a switching state of the power converter from a present switching state to a subsequent switching state based on the measured instantaneous current,
wherein to change the switching state of the power converter, the cyclic state controller is configured to follow a state machine comprising a plurality of switching states based on an electrical power desired at the electric load, wherein the plurality of switching states comprises at least the present

Assignees

• Gen Electric

Inventors

• El-Barbari Said Farouk
• Curbelo Alvaro Jorge Mari
• Schramm Simon Herbert

Classifications

• H02M2001/0009

  Electricity · mapped topic

• H02M3/33546 Primary

  with automatic control of the output voltage or current (H02M3/33561 takes precedence) · CPC title

• H02M3/33576 Primary

  having at least one active switching element at the secondary side of an isolation transformer · CPC title

• H02M7/53878

  by time shifting switching signals of one diagonal pair of the bridge with respect to the other diagonal pair · CPC title

• H02M1/0009

  Devices or circuits for detecting current in a converter · CPC title