DC to AC converter with magnitude based on duty ratio

Patent metadata

Field	Value
Publication number	US-12088216-B2
Application number	US-202217989192-A
Country	US
Kind code	B2
Filing date	Nov 17, 2022
Priority date	Apr 11, 2022
Publication date	Sep 10, 2024
Grant date	Sep 10, 2024

Abstract

A DC to AC converter includes an input configured to receive a DC input voltage, an output and two serially connected capacitors connected across the output. The two serially connected capacitors including a first capacitor and a second capacitor connected together at a connection node. The converter also includes a first parallel converter connected between the input and the connection node and a second parallel converter connected between the input and the connection and in parallel with the first parallel converter. The converter also includes a controller that selectively connects the first and second parallel converters to the input based on a first duty cycle (D1) and second duty cycle (D2), respectively. The controller determines D1 based on comparing a desired alternating current signal across the second first to a measured alternating current signal across the first capacitor such that D1 varies over time.

First claim

What is claimed is:

1. A DC to AC converter, the converter comprising:
an input configured to receive a DC input voltage;
an output;
two serially connected capacitors connected across the output, the two serially connected capacitors including a first capacitor and a second capacitor connected together at a connection node, wherein the second capacitor is connected between the connection node and ground;
a first parallel converter connected between the input and the connection node;
a second parallel converter connected between the input and the connection node and in parallel with the first parallel converter; and
a controller that selectively connects the first and second parallel converters to the input based on a first duty cycle (D 1 ) and second duty cycle (D 2 ), respectively, and wherein D 2 is a fixed value and D 1 is variable value, wherein D 1 varies based on a desired alternating current signal across the output.

2. The converter of claim 1 , wherein the first parallel converter is connected to the input for the a first duty cycle (D 1 ) that is a portion of a preselected time period (T) and the second parallel converter is connected to the input for a second duty cycle (D 2 ) that is a portion of the preselected time period (T).

3. The converter of claim 2 , wherein the voltage at the output is positive when D 2 is greater than D 1 and negative when D 2 is less than D 1 .

4. The converter of claim 1 , wherein the first parallel converter includes a first switch and first inductor connected in series between the input and the connection node.

5. The converter of claim 4 , wherein the second parallel converter includes a third switch and second inductor connected in series between the input and the connection node.

6. The converter of claim 5 , further comprising:
a second switch connected between an output of the first switch and first output terminal of the output; and
a fourth switch connected between an output of the third switch and a second output terminal of the output.

7. The converter of claim 6 , wherein when D 2 is greater than D 1 , the controller causes the converter to operate in three states;
wherein in a first state of the three states, the first and third switches are conductive and the second and fourth switches are open;
wherein in a second state of the three states, the first and fourth switches are open and the second and third switches are conductive; and
wherein in a third state of the three states, the first and third switches are open and the second and fourth switches are conductive.

8. The converter of claim 6 , wherein when D 1 is greater than D 2 , the controller causes the converter to operate in three states;
wherein in a first state of the three states, the first and third switches are conductive and the second and fourth switches are open;
wherein in a second state of the three states, the first and fourth switches are conductive and the second and third switches are open; and
wherein in a third state of the three states, the first and third switches are open and the second and fourth switches are conductive.

9. A method of operating a converter as recited in claim 6 , the method comprising:
determining a desired alternating current output at the output;
selecting a base value of D 1 that based on a desired bias value around which a voltage of across the first capacitor is to vary around, wherein the bias value is a negative value equal to half a peak to peak voltage offset of the desired alternating current output; and
selecting a value of D 2 that shifts the bias value offset to a desired level.

10. The method of claim 9 , wherein when D 2 is greater than D 1 , the controller causes the converter to operate in three states;
wherein in a first state of the three states, the first and third switches are conductive and the second and fourth switches are open;
wherein in a second state of the three states, the first and fourth switches are open and the second and third switches are conductive; and
wherein in a third state of the three states, the first and third switches are open and the second and fourth switches are conductive.

11. The method of claim 9 , wherein the controller causes the converter to be in the first state for a time period equal to D 1 *T.

12. The method of claim 11 , wherein the controller causes the converter to be in the first state and second states for a combined time period equal to D 2 *T.

13. The method of claim 9 , wherein when D 1 is greater than D 2 , the controller causes the converter to operate in three states
wherein in a first state of the three states, the first and third switches are conductive and the second and fourth switches are open;
wherein in a second state of the three states, the first and fourth switches are conductive and the second and third switches are open; and
wherein in a third state of the three states, the first and third switches are open and the second and fourth switches are conductive.

14. The method of claim 13 , wherein the controller causes the converter to be in the first state for a time period equal to D 2 *T.

15. The method of claim 14 , wherein the controller causes the converter to be in the first state and second states for a combined time period equal to D 1 *T.

16. A DC to AC converter, the converter comprising:
an input configured to receive a DC input voltage;
an output;
two serially connected capacitors connected across the output, the two serially connected capacitors including a first capacitor and a second capacitor connected together at a connection node;
a first parallel converter connected between the input and the connection node;
a second parallel converter connected between the input and the connection node and in parallel with the first parallel converter; and
a controller that selectively connects the first and second parallel converters to the input based on a first duty cycle (D 1 ) and second duty cycle (D 2 ), respectively, and wherein D 2 is a fixed value and D 1 is variable value, wherein D 1 varies based on a desired alternating current signal across the output;
wherein the first parallel converter includes a first switch and first inductor connected in series between the input and the connection node; wherein the second parallel converter includes a third switch and second inductor connected in series between the input and the connection node;
the converter further comprising:
a second switch connected between an output of the first switch and first output terminal of the output; and
a fourth switch connected between an output of the third switch and a second output terminal of the output;
wherein when D 2 is greater than D 1 , the controller causes the converter to operate in three states;
wherein in a first state of the three states, the first and third switches are conductive and the second and fourth switches are open;
wherein in a second state of the three states, the first and fourth switches are open and the second and third switches are conductive; and
wherein in a third state of the three states, the first and third switches are open and the second and fourth switches are conductive.

17. A DC to AC converter, the converter comprising:
an input configured to receive a DC input voltage;
an output;
two serially connected capacitors connected across the output, the two serially connected capacitors including a first capacitor and a second capacitor connected together at a connection node;
a first parallel converter connected between the input and the connection nod

Assignees

• Hamilton Sundstrand Corp

Inventors

• Somani Vaibhav Kumar
• Hanuman Kumbha Veera

Classifications

• H02M7/48

  using discharge tubes with control electrode or semiconductor devices with control electrode · CPC title

• H02M3/158

  including plural semiconductor devices as final control devices for a single load · CPC title

• H02M1/0093 Primary

  wherein the output is created by adding a regulated voltage to or subtracting it from an unregulated input · CPC title

• H02M7/539

  with automatic control of output wave form or frequency (H02M7/5375 - H02M7/5387 take precedence) · CPC title

• H02M1/0095

  Hybrid converter topologies, e.g. NPC mixed with flying capacitor, thyristor converter mixed with MMC or charge pump mixed with buck · CPC title