BIDIRECTIONAL ELECTRICAL SIGNAL CONVERTER

• US 20160181798A1
• Filed: 07/22/2014
• Published: 06/23/2016
• Est. Priority Date: 07/22/2013
• Status: Active Grant

• Current Assignee: Indiana University Research & Technology Corporation (Indiana University)
• Original Assignee: Indiana University Research & Technology Corporation (Indiana University)
• Inventors: IZADIAN, Afshin
• Granted Patent: US 10,033,182 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02J 3/32 using batteries with converting means
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: H02M 7/68 by static converters
• CPC Class Codes: H02M 7/797 using semiconductor devices only

Abstract

A bidirectional AC-to-DC and DC-to-AC circuit includes a first inductor-capacitor (LC) circuit connected to an AC power source, a transistor synchronized with the AC power source signal, a second LC circuit electrically connected to the synchronized transistor and the first inductor-capacitor circuit, a high-frequency switching transistor electrically connected to the second inductor-capacitor circuit and a direct current (DC) load, and a controller connected to the high-frequency switching transistor. The controller identifies an error between a measured DC output signal and a predetermined DC output signal that is applied to the DC load, and adjusts a duty cycle of a pulse width modulation (PWM) switching signal for the high-frequency transistor to reduce the identified error.

Claims

1. A power converter comprising:

a first inductor-capacitor circuit electrically connected to an alternating current (AC) power source;

a first switching transistor electrically connected to the first inductor-capacitor circuit;

a second inductor-capacitor circuit electrically connected to the first switching transistor and the first inductor-capacitor circuit;

a first high-frequency switching transistor electrically connected to the second inductor-capacitor circuit and a direct current (DC) load; and

a controller operatively connected to the first switching transistor and the first high-frequency switching transistor to operate the power converter in an AC-to-DC conversion mode, the controller being configured to;

operate the first switching transistor and the first high-frequency switching transistor to generate a DC output signal for the DC load from the AC power source;

identify an error between a measurement of the DC output signal from the first high-frequency switching transistor and a predetermined DC output signal level for the DC load; and

adjust a duty cycle of a pulse width modulation (PWM) switching signal to switch the high-frequency switching transistor at a predetermined frequency with the adjusted duty cycle to reduce the identified error in the DC output signal.

2. The power converter of claim 1, the controller being further configured to adjust the duty cycle of the PWM switching signal with reference to the identified error and a proportional-integral-differential (PID) controller.

3. The power converter of claim 2, the controller being further configured to:

switch off the first switching transistor when the first high-frequency switching transistor is switched on.

4. The power converter of claim 1 further comprising:

a voltage sensor operatively connected to an output of the AC power source and configured to identify a level of AC voltage from the AC power source; and

the controller being operatively connected to the first switching transistor and the voltage sensor, the controller being further configured to;

switch off the first switching transistor in response to a negative level of AC voltage from the AC power source.

5. The power converter of claim 1 further comprising:

a voltage sensor operatively connected to an output of the AC power source and configured to identify a level of AC voltage from the AC power source; and

the controller being operatively connected to the first switching transistor and the voltage sensor, the controller being further configured to;

switch off the first switching transistor in response to a positive level of AC voltage from the AC power source.

6. The power converter of claim 1 further comprising:

a current measurement sensor operatively connected to an output of the power converter and configured to identify a level of DC current applied to the DC load; and

the controller being operatively connected to the current measurement sensor and configured to;

switch off the high-frequency transistor in response to the level of DC current applied to the DC load exceeding a predetermined maximum level.

7. The power converter of claim 1 further comprising:

a second switching transistor electrically connected to the first inductor-capacitor circuit and configured to switch at predetermined switching frequency corresponding to a frequency of an AC output signal for an AC load;

a second high-frequency switching transistor electrically connected to the second inductor-capacitor circuit and a DC power source; and

the controller being operatively connected to the second switching transistor and the second high-frequency switching transistor to operate the power converter in a DC-to-AC conversion mode to generate the AC output signal for the AC load using the DC power source, the controller being further configured to;

generate a control signal at the predetermined switching frequency to operate the first switching transistor and the second switching transistor, the first switching transistor being switched off when the second switching transistor is switched on, and the first switching transistor being switched off when the second switching transistor is switched on;

identify another error between the AC output signal that is generated for the AC load and a predetermined AC output signal; and

adjust a duty cycle of a pulse width modulation (PWM) switching signal for the second high-frequency switching transistor to reduce the other error identified in the AC output signal.

8. The power converter of claim 7, the DC load being a battery that receives charge during the AC-to-DC conversion mode and the DC power source being the battery that discharges during the DC-to-AC conversion mode.

9. The power converter of claim 1, wherein the power converter is configured to generate the DC output at a selected voltage level to drive different DC loads using the AC input source.

10. The power converter of claim 5 further comprising an analog to digital converter (ADC) operatively connected to the voltage sensor and the controller.

11. The power converter of claim 6 further comprising an analog to digital converter (ADC) operatively connected to the current measurement sensor and the controller.

12. The power converter of claim 1, wherein the controller comprises a signal generator module configured to generate a sawtooth signal.

13. The power converter of claim 1, wherein the controller comprises a difference module that subtracts a measured voltage to a reference voltage.

14. The power converter of claim 13, wherein the controller comprises a proportional, integral, differential (PID) control module operatively connected to the difference module.

15. The power converter of claim 14, wherein the PID control module sets a control point threshold to adjust the duty cycle of the PWM switching signal with reference to the identified error and a proportional-integral-differential (PID) controller.

16. The power converter of claim 13, wherein the controller comprises a control module having control logic selected from the group consisting of PI, adaptive, self-tuning, variable structure, sliding mode, optimal, robust, and model predictive control logic.

17. The power converter of claim 1, the controller being further configured to adjust the duty cycle of the PWM switching signal with reference to the identified error and a controller having control logic selected from the group consisting of PI, adaptive, self-tuning, variable structure, sliding mode, optimal, robust, and model predictive control logic.

18. The power converter of claim 7, wherein the controller is configured to switch the second high-frequency switching transistor at a higher frequency than the output signal.

19. The power converter of claim 18, wherein the controller is configured to switch the second high-frequency switching transistor with varying duty cycles.

20. The power converter of claim 19, wherein the controller is configured to adjust an output level of the output signal to conform to the predetermined output AC waveform.