POWER CONVERTER FOR GENERATING BOTH POSITIVE AND NEGATIVE OUTPUT SIGNALS

• US 20140167715A1
• Filed: 03/27/2013
• Published: 06/19/2014
• Est. Priority Date: 12/13/2012
• Status: Active Grant

• Current Assignee: Analog Devices International Unlimited Company (Analog Devices, Inc.)
• Original Assignee: Linear Technology Corporation (Analog Devices, Inc.)
• Inventors: WU, Albert M., TOPP, Matthew Anthony
• Granted Patent: US 9,337,731 B2
• Time in Patent Office: Days
• US Class Current: 323/271
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02M 7/537 using semiconductor devices only, e.g. single switched pulse inverters

Abstract

A power converting system is responsive to an input signal to produce an output signal regulated with respect to the input signal. The power converting system has an input node for receiving the input signal, an output node for producing the output signal, and first and second inductive elements. The first inductive element has a first node coupled to the input node, the second inductive element has a first node coupled to the output node. A first switching element is coupled to a second node of the first inductive element. A first capacitive element is coupled between the second node of the first inductive element and a second node of the second inductive element. A control circuit is provided for controlling the first switching element. The control circuit is configured to set a duty cycle of the first switching element to a first value for providing the output signal of a first polarity in response to the input signal of the first polarity, and to set the duty cycle of the first switching element to a second value for providing the output signal of a second polarity in response to the input signal of the first polarity.

Claims

1. A power converting system responsive to an input signal to produce an output signal regulated with respect to the input signal, the system comprising:

an input node for receiving the input signal,

an output node for producing the output signal,

a first inductive element having a first node coupled to the input node,

a second inductive element having a first node coupled to the output node,

a first switching element coupled to a second node of the first inductive element,

a first capacitive element coupled between the second node of the first inductive element and a second node of the second inductive element, and

a control circuit for controlling the first switching element, the control circuit being configured to set a duty cycle of the first switching element to a first value for providing the output signal of a first polarity in response to the input signal of the first polarity, and to set the duty cycle of the first switching element to a second value for providing the output signal of a second polarity in response to the input signal of the first polarity.

2. The system of claim 1, wherein the first value of the duty cycle is in a first duty cycle range, and the second value of the duty cycle is in a second duty cycle range higher than the first duty cycle range.

3. The system of claim 2, wherein the control circuit is configured to set the duty cycle to a third value between the first duty cycle range and the second duty cycle range to provide a zero amplitude signal at the output node.

4. The system of claim 1, further comprising a second switching element coupled between the first node of the first inductive element and the second node of the second inductive element.

5. The system of claim 4, wherein the second switching element is turned off when the first switching element is turned on, and the second switching element is turned on when the first switching element is turned off.

6. The system of claim 1, further comprising an input filtering capacitive element coupled to the input node, and an output filtering capacitive element coupled to the output node.

7. The system of claim 1, wherein a regulated DC output signal is produced at the output node in response to a DC input signal at the input node.

8. The system of claim 1, wherein a regulated AC output signal is produced at the output node in response to a DC input signal at the input node.

9. The system of claim 1, wherein the control circuit is configured for sensing a combined current in the first and second inductive elements to control the first switching element.

10. The system of claim 1, wherein the control circuit is configured for sensing an output voltage of the power converting system to control the first switching element.

11. The system of claim 1, wherein the control circuit is configured for sensing an output current of the power converting system to control the first switching element.

12. The system of claim 1, wherein the control circuit is configured for sensing an input voltage of the power converting system to control the first switching element.

13. The system of claim 1, wherein the control circuit is configured for sensing an input current of the power converting system to control the first switching element.

14. The system of claim 1, wherein the control circuit includes an adjustable voltage reference block controlled by a control signal to produce a variable reference signal having a positive voltage value, a negative voltage value or a zero voltage value.

15. The system of claim 14, wherein the control circuit is configured to compare the variable reference signal with a signal representing the output voltage of the converting system, to produce a voltage control (VC) signal.

16. The system of claim 15, wherein the control circuit is further configured to compare the VC signal with a signal representing a combined current in the first and second inductive elements, to produce a driving signal that controls switching of the first switching element.

17. The system of claim 16, wherein the control circuit includes an inductive current sensing and slope compensation circuit for producing the signal representing a combined current in the first and second inductive elements.

18. The system of claim 17, wherein the inductive current sensing and slope compensation circuit comprises a ramp generator controlled by an oscillator for producing a ramp signal.

19. The system of claim 17, wherein the inductive current sensing and slope compensation circuit further includes a current sensor for sensing the combined current in the first and second inductive elements.

20. The system of claim 19, wherein the inductive current sensing and slope compensation circuit further includes an adder responsive to the ramp signal and to an output signal of the current sensor for producing the signal representing a sensed combined current in the first and second inductive elements.

21. The system of claim 20, wherein the control circuit further includes a latching circuit controlled by an output signal of the oscillator and by an output signal of a comparator that compares the voltage control signal with the signal representing a combined current in the first and second inductive elements, the latching circuit being configured to produce the driving signal that controls switching of the first switching element.

22. The system of claim 1, wherein the control circuit includes an adjustable current reference block responsive to a control signal for producing a current reference value of variable amplitude and polarity at a reference node coupled to the output node of the power converting system.

23. The system of claim 22, wherein the control circuit is configured for comparing a signal at the reference node with a fixed value to produce a voltage control (VC) signal.

24. The system of claim 23, wherein the control circuit is further configured to compare the VC signal with a signal representing a combined current in the first and second inductive elements, to produce a driving signal that controls switching of the first switching element.

25. A method of producing an output signal in response to an input signal, using a power converter having an input node for receiving the input signal, and output node for producing the output signal, a first inductive element coupled to the input node, a second inductive element coupled to the output node, a first capacitive element coupled between the first inductive element and the second inductive element, and a first switching element coupled to the first capacitive element, the method comprising the steps of:

controlling the first switching element to produce the output signal regulated with respect to the input signal,

setting a duty cycle of the first switching element to a first value to produce the output signal of a first polarity in response to the input signal of the first polarity, and

setting the duty cycle of the first switching element to a second value to produce the output signal of a second polarity in response to the input signal of the first polarity.

26. The method of claim 25, wherein the first value of the duty cycle is in a first duty cycle range, and the second value of the duty cycle is in a second duty cycle range higher than the first duty cycle range.

27. The method of claim 26 further comprising the step of setting the duty cycle to a third value between the first duty cycle range and the second duty cycle range to produce a zero amplitude signal at the output node.

28. The method of claim 27, wherein the power converter further has a second switching element coupled between the input node and the second inductive element, the method further comprising the steps of:

turning off the second switching element when the first switching element is turned on, and

turning on the second switching element when the first switching element is turned off.

29. The method of claim 27, wherein the step of controlling the first switching element includes sensing a combined current in the first and second inductive elements.

30. The method of claim 29, wherein the step of controlling the first switching element further includes producing a variable reference signal having a positive voltage value, a negative voltage value or a zero voltage value.

31. The method of claim 29, wherein the step of controlling the first switching element further includes producing a current reference value of variable amplitude and polarity at a reference node coupled to the output node of the power converter.