Digital Average Input Current Control in Power Converter

• US 20140320101A1
• Filed: 07/07/2014
• Published: 10/30/2014
• Est. Priority Date: 08/06/2007
• Status: Active Grant

• Current Assignee: Solaredge Technologies Incorporated
• Original Assignee: Solaredge Technologies Incorporated
• Inventors: Fishelov, Amir, Gazit, Meir, Radimov, Nikolay
• Granted Patent: US 9,673,711 B2
• Time in Patent Office: Days
• US Class Current: 323/283
• CPC Class Codes: H02M 3/157 with digital control
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02M 3/1582 Buck-boost converters H02M3/1584 takes precedence
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

A digital average-input current-mode control loop for a DC/DC power converter. The power converter may be, for example, a buck converter, boost converter, or cascaded buck-boost converter. The purpose of the proposed control loop is to set the average converter input current to the requested current. Controlling the average input current can be relevant for various applications such as power factor correction (PFC), photovoltaic converters, and more. The method is based on predicting the inductor current based on measuring the input voltage, the output voltage, and the inductor current. A fast cycle-by-cycle control loop may be implemented. The conversion method is described for three different modes. For each mode a different control loop is used to control the average input current, and the control loop for each of the different modes is described. Finally, the algorithm for switching between the modes is disclosed.

Claims

1-20. -20. (canceled)

21. A method, comprising:

sampling an inductor current of an inductor of a converter;

sampling an input voltage of the converter;

sampling an output voltage of the converter;

predicting, by a controller, the inductor current based on the sampled inductor current, the sampled input voltage, and the sampled output voltage; and

controlling a duty cycle based on the predicted inductor current to cause an input current of the converter to approach a desired input current.

22. The method of claim 21, wherein predicting the inductor current comprises predicting the inductor current for a second cycle based on the sampled inductor current for a first cycle.

23. The method of claim 22, wherein controlling the duty cycle comprises controlling the duty cycle for the second cycle.

24. The method of claim 21, wherein controlling the duty cycle comprises performing a triangle pulse width modulation.

25. The method of claim 21, wherein the converter comprises a cascaded buck-boost converter.

26. The method of claim 21, wherein the controller comprises a first pre-programmed control module for a buck mode of the converter, a second pre-preprogrammed control module for a boost mode of the converter, and a third pre-programmed control module for an alternating buck-boost mode of the converter.

27. The method of claim 21, wherein the controller comprises three pre-programmed control modules for controlling the input current of the converter according to three operational modes of the converter, respectively.

28. The method of claim 21, further comprising:

transferring the converter from a first operational mode to a second operational mode in response to a duty cycle dropping below or climbing above a threshold.

29. The method of claim 21, further comprising:

transferring the converter from an alternating buck-boost mode to a buck mode or a boost mode in response to a duty cycle dropping below or climbing above a threshold for at least a predetermined number of cycles.

30. An apparatus, comprising:

a circuit configured to;

sample an inductor current of an inductor of a converter;

sample an input voltage of the converter; and

sample an output voltage of the converter;

a controller configured to;

predict the inductor current based on the sampled inductor current, the sampled input voltage, and the sampled output voltage; and

control a duty cycle based on the predicted inductor current to cause an input current of the converter to approach a desired input current.

31. The apparatus of claim 30, wherein predicting the inductor current comprises predicting the inductor current for a second cycle based on the sampled inductor current for a first cycle.

32. The apparatus of claim 31, wherein controlling the duty cycle comprises controlling the duty cycle for the second cycle.

33. The apparatus of claim 30, wherein controlling the duty cycle comprises performing a triangle pulse width modulation.

34. The apparatus of claim 30, further comprising the converter,

wherein the converter comprises a cascaded buck-boost converter, and

wherein the controller comprises a first pre-programmed control module for a buck mode of the converter, a second pre-preprogrammed control module for a boost mode of the converter, and a third pre-programmed control module for an alternating buck-boost mode of the converter.

35. The apparatus of claim 30, wherein the controller is further configured to:

transfer the converter from a first operational mode to a second operational mode in response to a duty cycle dropping below or climbing above a threshold.

36. A method, comprising:

predicting, by a controller, an inductor current of an inductor of a converter; and

controlling a duty cycle based on the predicted inductor current to cause an input current of the converter to approach a desired input current; and

37. The method of claim 36, further comprising:

transferring the converter from an alternating buck-boost mode to a buck mode or a boost mode in response to the duty cycle dropping below or climbing above a threshold for at least a predetermined number of cycles.

38. The method of claim 37, wherein the transferring depends at least on the desired input current.

39. The method of claim 37, wherein the predicting of the inductor current is performed according to an algorithm that depends on whether the converter is in the alternating buck-boost mode, the buck mode, or the boost mode.

40. The method of claim 36, wherein the predicting of the inductor current is performed according to an algorithm that depends on whether the converter is in an alternating buck-boost mode, a buck mode, or a boost mode.