Patent Publication Number: US-2022224127-A1

Title: Configurable network for enabling efficient charging and loading of two battery cells

Description:
RELATED APPLICATION 
     The present disclosure claims priority to U.S. Provisional Patent Application Ser. No. 63/135,258 filed Jan. 8, 2021, which is incorporated by reference herein in its entirety. 
    
    
     FIELD OF DISCLOSURE 
     The present disclosure relates in general to circuits for electronic devices, including without limitation personal audio devices such as wireless telephones and media players, and more specifically, a configurable network for enabling efficient charging and loading of two battery cells. 
     BACKGROUND 
     Portable electronic devices, including wireless telephones, such as mobile/cellular telephones, tablets, cordless telephones, mp3 players, smart watches, health monitors, and other consumer devices, are in widespread use. Such a portable electronic device may include one or more rechargeable battery cells for powering components of the portable electronic device. For example, the use of two series-coupled cells is common in portable electronic devices. 
     Using an existing charging and battery loading architecture for two cells, a switching network may direct-charge two series-coupled cells to avoid charger integrated circuit losses that may limit fast charging. In such an architecture, a low-voltage load may be coupled via a 2:1 step-down charge pump that may incur switching losses, and reduce battery life. In addition, a portion of the load may require higher voltage and thus may incur further boosting losses due to a boost converter for stepping up voltage from that needed for the low-voltage load to that needed for the higher-voltage load. Further, a cell balancing circuit may be required when using the existing architecture. 
     SUMMARY 
     In accordance with the teachings of the present disclosure, one or more disadvantages and problems associated with existing approaches to battery charging and loading architectures may be reduced or eliminated. 
     In accordance with embodiments of the present disclosure, a two-cell battery management system may include a switching network comprising a plurality of switches configured to electrically couple two battery cells to one another and a first load configured to receive electrical energy from the two battery cells and control circuitry configured to dynamically control the switching network among a plurality of switching configurations comprising a first switching configuration in which the first load is in parallel with both of the two battery cells, a second switching configuration in which the first load is in parallel with a first battery cell of the two battery cells and is electrically isolated from a second battery cell of the two battery cells, and a third switching configuration in which the first load is in parallel with the second battery cell and is electrically isolated from the first battery cell. 
     In accordance with these and other embodiments of the present disclosure, a method for managing a system having two battery cells may include dynamically controlling a switching network comprising a plurality of switches configured to electrically couple the two battery cells to one another and a first load configured to receive electrical energy from the two battery cells, wherein dynamic controlling comprises controlling the switching network among a plurality of switching configurations comprising a first switching configuration in which the first load is in parallel with both of the two battery cells, a second switching configuration in which the first load is in parallel with a first battery cell of the two battery cells and is electrically isolated from a second battery cell of the two battery cells, and a third switching configuration in which the first load is in parallel with the second battery cell and is electrically isolated from the first battery cell. 
     In accordance with these and other embodiments of the present disclosure, a portable electronic device may include two battery cells and a two-cell battery management system comprising a switching network comprising a plurality of switches configured to electrically couple the two battery cells to one another and a first load configured to receive electrical energy from the two battery cells and control circuitry configured to dynamically control the switching network among a plurality of switching configurations. The plurality of switching configurations may include a first switching configuration in which the first load is in parallel with both of the two battery cells, a second switching configuration in which the first load is in parallel with a first battery cell of the two battery cells and is electrically isolated from a second battery cell of the two battery cells, and a third switching configuration in which the first load is in parallel with the second battery cell and is electrically isolated from the first battery cell. 
     Technical advantages of the present disclosure may be readily apparent to one skilled in the art from the figures, description and claims included herein. The objects and advantages of the embodiments will be realized and achieved at least by the elements, features, and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are examples and explanatory and are not restrictive of the claims set forth in this disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein: 
         FIG. 1  illustrates an example portable electronic device, in accordance with embodiments of the present disclosure; 
         FIG. 2  illustrates a circuit diagram of selected components of a portable electronic device, in accordance with embodiments of the present disclosure; 
         FIGS. 3A and 3B  illustrate two alternating phases of operation of a first mode of a switching network with a battery charger present and current being drawn by both the high-voltage load and the low-voltage load of the portable electronic device of  FIGS. 1 and 2 , in accordance with embodiments of the present disclosure; 
         FIGS. 4A and 4B  illustrate two alternating phases of operation of a second mode of a switching network with a battery charger absent and current being drawn by both the high-voltage load and the low-voltage load of the portable electronic device of  FIGS. 1 and 2 , in accordance with embodiments of the present disclosure; 
         FIG. 5  illustrates operation of a third mode of a switching network with a battery charger absent and current being drawn by the low-voltage load, but not the high-voltage load, of the portable electronic device of  FIGS. 1 and 2 , in accordance with embodiments of the present disclosure; 
         FIGS. 6A and 6B  illustrate two alternating phases of operation of a fourth mode of a switching network with a legacy battery charger present in parallel with the low-voltage load of the portable electronic device of  FIGS. 1 and 2  and current being drawn by both the high-voltage load and the low-voltage load of the portable electronic device of  FIGS. 1 and 2 , in accordance with embodiments of the present disclosure; 
         FIG. 7  illustrates operation of a fifth mode of a switching network with a legacy battery charger present and current being drawn by the low-voltage load, but not the high-voltage load, of the portable electronic device of  FIGS. 1 and 2 , in accordance with embodiments of the present disclosure; and 
         FIGS. 8A and 8B  depict two alternating phases of operation of a sixth mode of a switching network with a legacy battery charger present in parallel with the low-voltage load of the portable electronic device of  FIGS. 1 and 2 , in which the switching network enables pulsed current charging of battery cells, in accordance with embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates an example portable electronic device  1 , in accordance with embodiments of the present disclosure.  FIG. 1  depicts portable electronic device  1  coupled to a headset  3  in the form of a pair of earbud speakers  8 A and  8 B. Headset  3  depicted in  FIG. 1  is merely an example, and it is understood that portable electronic device  1  may be used in connection with a variety of audio transducers, including without limitation, headphones, earbuds, in-ear earphones, and external speakers. A plug  4  may provide for connection of headset  3  to an electrical terminal of portable electronic device  1 . Portable electronic device  1  may provide a display to a user and receive user input using a touch screen  2 , or alternatively, a standard liquid crystal display (LCD) may be combined with various buttons, sliders, and/or dials disposed on the face and/or sides of portable electronic device  1 . 
       FIG. 2  illustrates a block diagram of selected components of a portable electronic device  1 , in accordance with embodiments of the present disclosure. As shown in  FIG. 2 , portable electronic device  1  may include a battery charger  16 , at least two battery cells  22  (e.g., battery cells  22 A and  22 B), a high-voltage load  18 A comprising one or more downstream components, a low-voltage load  18 B comprising one or more downstream components, and a capacitor  24  coupled in parallel with low-voltage load  18 B, and a switching network  20 , wherein switching network  20  comprises a plurality of switches  26  (e.g., switches  26 A,  26 B,  26 C,  26 D,  26 E,  26 F,  26 G, and  26 H), all arranged as shown in  FIG. 2 . Further, portable electronic device  1  may include a control circuit  30  configured to control switches  26  (although connectivity for control signals communicated to control inputs of switches  26  are not depicted for purposes of clarity and exposition). 
     Battery charger  16  may include any system, device, or apparatus configured to charge a battery, for example by delivering electrical energy to a battery in order that such battery converts the electrical energy to chemical energy that is stored in such battery. In some embodiments, battery charger  16  may include a wired charger configured to draw electrical energy from an electrical power outlet or from a power bank. In other embodiments, battery charger  16  may include a wireless charger configured to draw electrical energy via inductive coupling from a wireless charging pad or similar device. In some embodiments, a portable electronic device  1  may include both a wired charger and a wireless charger. While  FIG. 2  (and other FIGURES) depict battery charger  16  integral to portable electronic device  1 , in some embodiments, all or a portion of battery charger  16  may be external to portable electronic device  1 . 
     Each battery cell  22  may include any system, device, or apparatus configured to convert chemical energy stored within such battery cell  22  to electrical energy for powering downstream components (e.g., of high-voltage load  18 A and low-voltage load  18 B) of portable electronic device  1 . Further, each battery cell  22  may also be configured to recharge, in which it may convert electrical energy received by such battery cell  22  into chemical energy to be stored for later conversion back into electrical energy. For example, in some embodiments, a battery cell  22  may comprise a lithium-ion cell. 
     Downstream components of high-voltage load  18 A and low-voltage load  18 B may include any suitable functional circuits or devices of portable electronic device  1 , including without limitation processors, audio coder/decoders, amplifiers, display devices, etc. As their names imply, high-voltage load  18 A may include downstream components requiring a higher voltage and/or higher power than those downstream components of low-voltage load  18 B. 
     As shown in  FIG. 2 , switch  26 A may be coupled between battery charger  16  and a high-voltage rail. Switch  26 B may be coupled between high-voltage load  18 A and the high-voltage rail. Switch  26 C may be coupled between a cathode of battery cell  22 A and the high-voltage rail. Switch  26 D may be coupled between an anode of battery cell  22 A and a cathode of battery cell  22 B. Accordingly, when switches  26 A,  26 B,  26 C, and  26 D are all activated (e.g., on, enabled, closed), battery charger  16 , high-voltage load  18 A, and the series combination of battery cells  22  may be coupled in series between the high-voltage rail and a ground rail. 
     As shown in  FIG. 2 , switch  26 E may be coupled between the cathode of battery cell  22 A and a first terminal of low-voltage load  18 B. Switch  26 F may be coupled between the anode of battery cell  22 A and a second terminal of low-voltage load  18 B. Switch  26 G may be coupled between the cathode of battery cell  22 B and the first terminal of low-voltage load  18 B. Switch  26 H may be coupled between the anode of battery cell  22 B and the second terminal of low-voltage load  18 B. 
     As described in more detail below, control circuit  30  may control switches  26  of switching network  20  to dynamically configure coupling among battery cells  22 , charger  16 , high-voltage load  18 A, and low-voltage load  18 B, in order to minimize losses and simplify design as compared to existing approaches. 
       FIGS. 3A and 3B  illustrate two alternating phases of a first mode of operation of switching network  20  with battery charger  16  present and current being drawn by both high-voltage load  18 A and low-voltage load  18 B, in accordance with embodiments of the present disclosure. In both phases of the first mode, control circuit  30  may cause switches  26 A,  26 B,  26 C and  26 D to activate, such that high-voltage load  18 A and battery charger  16  are coupled to the series combination of both battery cells  22 . Little or no power conversion losses may be incurred in delivering electrical energy from battery cells  22  to high-voltage load  18 A. On the other hand, during a first phase of the first mode, as shown in  FIG. 3A , control circuit  30  may cause switches  26 E and  26 F to activate, and switches  26 G and  26 H to deactivate (e.g., turn off, become disabled, open). Similarly, during a second phase of the first mode, as shown in  FIG. 3B , control circuit  30  may cause switches  26 E and  26 F to deactivate, and switches  26 G and  26 H to activate. Thus, during the first mode, low-voltage load  18 B may be alternately coupled to battery cell  22 A during the first phase and to battery cell  22 B in the second phase. 
     In effect, switches  26 E,  26 F,  26 G, and  26 H may replace switches of a step-down charge pump that may be present in traditional architectures. In the architecture shown in  FIGS. 3A and 3B , battery cells  22  may effectively act as fly capacitors. Because the equivalent capacitance of a battery cell  22  may be much larger than capacitance of physical capacitors traditionally used as fly capacitors, switching frequency may be reduced as compared to traditional architectures, leading to minimal switching losses. Further, the alternative coupling of low-voltage load  18 B between battery cell  22 A and  22 B may automatically balance battery cells  22 , avoiding the need for cell balancing circuitry typically required in traditional architectures. 
       FIGS. 4A and 4B  illustrate two alternating phases of a second mode of operation of switching network  20  with battery charger  16  absent and current being drawn by both high-voltage load  18 A and low-voltage load  18 B, in accordance with embodiments of the present disclosure. By “absent,” it is intended to mean battery charger  16  is inactive (e.g., not plugged in to a source of electrical energy) or otherwise decoupled from the remainder of portable electronic device  1  (e.g., by way of deactivation of switch  26 A). 
     In both phases of the second mode, control circuit  30  may cause switches  26 B,  26 C and  26 D to activate, such that high-voltage load  18 A is coupled to a series combination of both battery cells  22 . Little or no power conversion losses may be incurred in delivering electrical energy from battery cells  22  to high-voltage load  18 A. On the other hand, during a first phase of the second mode, as shown in  FIG. 4A , control circuit  30  may cause switches  26 E and  26 F to activate, and switches  26 G and  26 H to deactivate. Similarly, during a second phase of the second mode, as shown in  FIG. 4B , control circuit  30  may cause switches  26 E and  26 F to deactivate, and switches  26 G and  26 H to activate. Thus, during the second mode, low-voltage load  18 B may be alternately coupled to battery cell  22 A during the first phase and to battery cell  22 B in the second phase. 
     In some instances, high-voltage load  18 A may not draw current (e.g., when no audio is played back from portable electronic device  1 ). In such instances, switching network  20  may operate in a third mode of operation.  FIG. 5  illustrates a third mode of operation of switching network  20  with battery charger  16  absent and current being drawn by low-voltage load  18 B but not by high-voltage load  18 A, in accordance with embodiments of the present disclosure. In the third mode, control circuit  30  may cause switches  26 A,  26 B,  26 C and  26 D to deactivate, and cause switches  26 E,  26 F,  26 G, and  26 H to activate, thus placing battery cell  22 A and battery cell  22 B in parallel with one another (and both battery cells  22  in parallel with low-voltage load  18 B). In the switch configuration of the third mode, no switching may occur, and thus switching losses may be reduced to zero. 
     In the systems and methods described above with respect to  FIGS. 3A through 5 , a two-cell battery management system is disclosed. Such system may include at least a first load (e.g., low-voltage load  18 B), and a switching network (e.g. switching network  20  of switches  26 ) coupling the first load to the two battery cells (e.g., battery cells  22 ). In a first configuration of the switching network, the switching network may couple the first load to the two battery cells in parallel (e.g.,  FIG. 5 ). In a second configuration of the switching network, the switching network may couple the first load in parallel with the first battery cell and isolate the first load from the second battery cell (see  FIG. 4A ). In a third configuration of the switching network, the switching network may couple the first load in parallel with the second battery cell and isolate the first load from the first battery cell (e.g.,  FIG. 4B ). In some embodiments, the two-cell battery management system may further include a second load (e.g., high-voltage load  18 A), with the switching network coupling the second load to the battery cells. In a fourth configuration of the switching network, the switching network may couple the second load in parallel to the series combination of the first battery cell and the second battery cell (e.g.,  FIGS. 3A and 3B ). 
     In some instances, portable electronic device  1  may need to support a legacy charger having a lower output voltage (e.g., 4.5 volts) than that of battery charger  16  (e.g., 9 volts).  FIGS. 6A and 6B  illustrate two alternating phases of operation of a fourth mode of switching network  20  with a legacy battery charger  17  present in parallel with low-voltage load  18 B and current being drawn by both high-voltage load  18 A and low-voltage load  18 B, in accordance with embodiments of the present disclosure. As shown in  FIGS. 6A and 6B , switching network  20  may include a ninth switch  26 I coupled between legacy battery charger  17  and low-voltage load  18 B such that legacy battery charger  17  and low-voltage load  18 B are in parallel when switch  26 I is activated. 
     In both phases of the fourth mode, control circuit  30  may cause switches  26 B,  26 C and  26 D to activate, such that high-voltage load  18 A is coupled to a series combination of both battery cells  22 . Further, control circuit  30  may cause switch  26 I to activate, such that legacy battery charger  17  is coupled in parallel with low-voltage load  18 B. During a first phase of the fourth mode, as shown in  FIG. 6A , control circuit  30  may cause switches  26 E and  26 F to activate, and switches  26 G and  26 H to deactivate. Similarly, during a second phase of the fourth mode, as shown in  FIG. 6B , control circuit  30  may cause switches  26 E and  26 F to deactivate, and switches  26 G and  26 H to activate. Thus, during the fourth mode, low-voltage load  18 B may be alternately coupled to battery cell  22 A during the first phase and to battery cell  22 B in the second phase. In addition, current may flow through switches  26 E,  26 F,  26 G, and  26 H in a direction opposite to that of the current flow in the first mode of operation (e.g.,  FIGS. 3A and 3B ) and the second mode of operation (e.g.,  FIGS. 4A and 4B ). Further, the alternative coupling of legacy battery charger  17  between battery cell  22 A and  22 B may automatically balance battery cells  22 , avoiding the need for cell balancing circuitry typically required in traditional architectures. 
     In some instances, high-voltage load  18 A may not draw current (e.g., when no audio is played back from portable electronic device  1 ). In such instances, switching network  20  may operate in a fifth mode of operation.  FIG. 7  illustrates a fifth mode of operation of switching network  20  with a legacy battery charger  17  present in parallel with low-voltage load  18 B and current being drawn by low-voltage load  18 B but not by high-voltage load  18 A, in accordance with embodiments of the present disclosure. In the fifth mode, control circuit  30  may cause switches  26 A,  26 B,  26 C and  26 D to deactivate, and cause switches  26 E,  26 F,  26 G,  26 H, and  26 I to activate, thus placing battery cell  22 A and battery cell  22 B in parallel with one another (and both battery cells  22  in parallel with low-voltage load  18 B). 
     In the systems and methods described above with respect to  FIGS. 4A through 7 , a two-cell battery management system is disclosed. Such system may include at least a first load (e.g., low-voltage load  18 B), and a switching network (e.g. switching network  20  of switches  26 ) coupling the first load to the two battery cells (e.g., battery cells  22 ). In a first configuration of the switching network, the switching network may couple the first load to the two battery cells in parallel (e.g.,  FIG. 5 ). In a second configuration of the switching network, the switching network may couple the first load in parallel with the first battery cell and isolate the first load from the second battery cell (see  FIG. 4A ). In a third configuration of the switching network, the switching network may couple the first load in parallel with the second battery cell and isolate the first load from the first battery cell (e.g.,  FIG. 4B ). 
     In some embodiments, the two-cell battery management system may have a first charger (e.g., legacy battery charger  17 ), with a switching network (e.g., switching network  20  of switches  26 ) coupling the first charger to the first load, and a third switching configuration of the switching network coupling the first charger in parallel with the first load. Further, in some embodiments, the two-cell battery management system may further include a second load (e.g., high-voltage load  18 A), with the switching network coupling the second load to the battery cells. In a fourth configuration, the switching network may couple the second load in parallel to the series combination of the first battery cell and the second battery cell (e.g.,  FIGS. 6A and 6B ). In these and other embodiments, the two-cell battery management system may have a second charger (e,g, battery charger  16 ), with the switching network coupling the second charger to the battery cells, with a fifth switching configuration coupling the second charger in parallel with a series combination of the battery cells. 
       FIGS. 8A and 8B  depict two alternating phases of operation of a sixth mode of switching network  20  with legacy battery charger  17  present in parallel with low-voltage load  18 B, in which switching network  20  enables pulsed current charging of battery cells  22 , in accordance with embodiments of the present disclosure. When high-voltage load  18 A does not draw current, in both phases of the sixth mode, control circuit  30  may cause switch  26 I to activate, such that legacy battery charger  17  is coupled in parallel with low-voltage load  18 B. During a first phase of the sixth mode, as shown in  FIG. 8A , control circuit  30  may cause switches  26 E and  26 F to activate, and switches  26 G and  26 H to deactivate, such that battery cell  22 A charges from legacy battery charger  17 . Similarly, during a second phase of the sixth mode, as shown in  FIG. 8B , control circuit  30  may cause switches  26 E and  26 F to deactivate, and switches  26 G and  26 H to activate, such that battery cell  22 B charges from legacy battery charger  17 . Thus, during the sixth mode, legacy battery charger  17  may be alternately coupled to battery cell  22 A during the first phase and to battery cell  22 B in the second phase, thus generating alternating pulses of electrical energy to battery cell  22 A and battery cell  22 B, thus enabling pulsed current charging which may minimize battery degradation. 
     As used herein, when two or more elements are referred to as “coupled” to one another, such term indicates that such two or more elements are in electronic communication or mechanical communication, as applicable, whether connected indirectly or directly, with or without intervening elements. 
     This disclosure encompasses all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Similarly, where appropriate, the appended claims encompass all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Moreover, reference in the appended claims to an apparatus or system or a component of an apparatus or system being adapted to, arranged to, capable of, configured to, enabled to, operable to, or operative to perform a particular function encompasses that apparatus, system, or component, whether or not it or that particular function is activated, turned on, or unlocked, as long as that apparatus, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative. Accordingly, modifications, additions, or omissions may be made to the systems, apparatuses, and methods described herein without departing from the scope of the disclosure. For example, the components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses disclosed herein may be performed by more, fewer, or other components and the methods described may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order. As used in this document, “each” refers to each member of a set or each member of a subset of a set. 
     Although exemplary embodiments are illustrated in the figures and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should in no way be limited to the exemplary implementations and techniques illustrated in the drawings and described above. 
     Unless otherwise specifically noted, articles depicted in the drawings are not necessarily drawn to scale. 
     All examples and conditional language recited herein are intended for pedagogical objects to aid the reader in understanding the disclosure and the concepts contributed by the inventor to furthering the art, and are construed as being without limitation to such specifically recited examples and conditions. Although embodiments of the present disclosure have been described in detail, it should be understood that various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the disclosure. 
     Although specific advantages have been enumerated above, various embodiments may include some, none, or all of the enumerated advantages. Additionally, other technical advantages may become readily apparent to one of ordinary skill in the art after review of the foregoing figures and description. 
     To aid the Patent Office and any readers of any patent issued on this application in interpreting the claims appended hereto, applicants wish to note that they do not intend any of the appended claims or claim elements to invoke 35 U.S.C. § 112(f) unless the words “means for” or “step for” are explicitly used in the particular claim.