Autonomous battery life raiser

Abstract

A circuit for autonomous battery life enhancement includes a power source, an output, a current sense module located on an electrical load path between the power source and the output, a direct current-direct current (DC-DC) converter, and a capacitor electrically connected to the DC-DC converter.

Description

Technical Field

[0001] Aspects of the present disclosure relate to a circuit, system, and method for autonomous battery life enhancement. Background Art

[0002] The lifespan of battery-powered applications depends on the type of battery and its intended use. Batteries gradually degrade until they can no longer provide power. This degradation is more severe for higher load currents. This is due to two factors.

[0003] The first factor is that batteries have a high internal resistance, which causes a voltage drop when discharged at a load current. In addition, the internal resistance of a battery increases with the cumulative power consumed by the battery throughout its service life. Compared to a new, unused battery, this internal resistance can be more than ten times higher for a battery nearing the end of its life cycle. This gradual increase in internal resistance means that the voltage across the load (V LOAD ) will progressively decrease over time and eventually fall below a voltage value at which the application will no longer function (reach its functional end point FEP) and the battery must be replaced.

[0004] The second factor is the total charge that can be drawn from the battery before the voltage decreases over time. This depends on the discharge current level during the battery's service life. For high pulse discharges (i.e. pulsed load currents), the battery capacity is Figure 1 Shown in. Figure 1 It shows how the internal resistance (IR) increases with increasing (total) consumed battery capacity. The closed circuit voltage (CCV) for pulsed current and constant background current decreases with (total) consumed battery capacity.

[0005] A current approach to overcoming the above mentioned factors (or problems) of high battery internal resistance and high battery discharge current is through the use of decoupling capacitors, such as Figure 2 This is shown in the figure with the reference numeral "C". Connecting a large decoupling capacitor in parallel with the battery reduces the (parallel connection) impedance of the high-frequency load pulse, which reduces the voltage drop and, therefore, the peak battery discharge current. However, the capacitance of the decoupling capacitor varies proportionally with the peak load current amplitude and pulse width, and so does the required printed circuit board (PCB) space and, therefore, the cost.

[0006] A solution for preventing high battery discharge currents would be to introduce a current limiter that can be inserted along the electrical load (in series with the battery) between the battery and the decoupling capacitors, such as Figure 3 Although the current limiter will reduce the battery discharge current, the output voltage of the load (V OUT ) will drop to a level that causes the system to fail.

[0007] A solution for stabilizing the output voltage would be to introduce a DC-DC converter across the electrical load between the decoupling capacitors and the output, such as Figure 4 Of course, this can be combined with a current limiter as mentioned above, such as Figure 5 While this solves the problem of voltage drop during high load pulses, large decoupling capacitors are still required to prevent even higher battery currents when the voltage output remains high, which again results in capacitors taking up large circuit area and increasing cost. Another disadvantage is that the converter is always connected in series with the battery, with associated power losses.

[0008] Therefore, there is a need to extend the life of the battery. Summary of the Invention

[0009] The following describes an overview of aspects of certain examples disclosed herein. It should be understood that these aspects are presented merely to provide the reader with a brief overview of these specific embodiments, and these aspects are not intended to limit the scope of the present disclosure. In fact, the present disclosure may encompass multiple aspects and / or combinations of multiple aspects that may not be described.

[0010] According to a first aspect of the present invention, a circuit for autonomous battery life enhancement is provided, the circuit comprising: a power supply; an output, the output being electrically connected to the power supply, the electrical connection forming an electrical load path; a current sensing module, the current sensing module being located on the electrical load path between the power supply and the output; a DC-DC converter, the DC-DC converter being positioned in parallel with the current sensing module and the electrical load path and being electrically connected to the electrical load path at both ends of the current sensing module; and a capacitor, the capacitor being electrically connected to the DC-DC converter, wherein the DC-DC converter comprises: an input module, the input module being electrically connected to the electrical load path between the power supply and the current sensing module and being configured to receive an electric charge from the power supply; an output module, the output module being electrically connected to the current sensing module and the output an electrical load path between the input module and the output module, configured to transfer charge from the capacitor; a connecting module, the connecting module being connected to the capacitor; a charging module, the charging module being configured to connect the input module with the connecting module; a buffer, the buffer being configured to connect the connecting module with the output module; and a controller, the controller being connected to the charging module, the buffer and the current sensing module, wherein in operation, the controller is configured to, when the current sensed by the current sensing module is lower than a first threshold, instruct the charging module to transfer a first charge from the input module to the connecting module to charge the capacitor; and, when the current sensed by the current sensing module is higher than the first threshold, instruct the buffer to transfer a second charge from the capacitor connected to the connecting module to the output module to replace the sensed current on the electrical load path until the voltage of the capacitor reaches the threshold.

[0011] This has the advantage that the DC-DC converter can autonomously decide when to switch from charge mode to discharge mode (and vice versa) because the DC-DC converter independently decides when to start and stop charge mode and discharge mode without the need for external circuitry.

[0012] According to another aspect of the present invention, a charging module in a DC-DC converter includes a first inductor and at least one switch, and a buffer includes a first inductor and at least one switch.

[0013] According to another aspect of the present invention, the charging module and the buffer share at least one switch.

[0014] According to another aspect of the present invention, the DC-DC converter further includes a sample and hold module configured to store a voltage from a power supply.

[0015] According to another aspect of the invention, the capacitor has a positive polarity, wherein the negative capacitor voltage is positive with respect to ground.

[0016] According to another aspect of the invention, the capacitor has a negative polarity, wherein the capacitor voltage is negative with respect to ground.

[0017] According to another aspect of the present invention, the current sensing module is a resistor.

[0018] According to another aspect of the present invention, a method for operating a circuit for autonomous battery life enhancement includes: sensing a current on an electrical load path between a power source and an output by a current sensing module, wherein when the sensed current is lower than a first threshold, a controller of a DC-DC converter transfers charge from the electrical load path to an input module of the DC-DC converter, the controller and a charging module of the DC-DC converter transfer the charge from the input module to a connection module of the DC-DC converter, and the controller and the charging module transfer the charge to a capacitor connected to the connection module; and when the sensed current is higher than the first threshold, the controller and a buffer of the DC-DC converter transfer the charge from the capacitor to the connection module of the DC-DC converter until a voltage of the capacitor reaches a threshold, the controller and the buffer transfer the charge from the connection module of the DC-DC converter to the output module of the DC-DC converter, and the controller transfers the charge at the sensed current level from the output module to the electrical load path to the output.

[0019] According to another aspect of the present invention, the transferred charge passes through a first inductor of a DC-DC converter and at least one switch of the DC-DC converter.

[0020] According to another aspect of the present invention, the transferred charges pass through at least one shared switch.

[0021] According to another aspect of the present invention, the method further comprises the step of storing the voltage of the power supply in a sample and hold module in the DC-DC converter.

[0022] According to another aspect of the present invention, the current passes through the same inductor and the at least one switch.

[0023] According to another embodiment of the present invention, the charge is passed through the ground of the DC-DC converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to enable a detailed understanding of the features of the present disclosure, a more particular description will be given with reference to embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings illustrate only typical embodiments and, therefore, should not be considered as limiting the scope thereof. The drawings are provided to facilitate understanding of the present disclosure and, therefore, are not necessarily drawn to scale. The advantages of the claimed subject matter will become apparent to those skilled in the art upon reading this specification in conjunction with the accompanying drawings, in which like reference numerals are used to designate like elements, and wherein:

[0025] Figure 1 The cell voltage and internal resistance (IR) versus depleted capacity are shown for constant background (Bkgnd) and pulsed current (Pulse).

[0026] Figure 2 Decoupling capacitors are shown for buffering the battery.

[0027] Figure 3 Decoupling capacitors are shown for buffering the battery with a battery current limiter.

[0028] Figure 4 Decoupling capacitors and a DC-DC converter are shown for regulating the output voltage.

[0029] Figure 5 Decoupling capacitors, current limiters, and DC-DC converters are shown for regulating the output voltage.

[0030] Figure 6 A circuit for autonomous battery life enhancement according to an embodiment of the present invention is shown.

[0031] Figure 7 shows an embodiment according to the present invention Figure 6 The current path of the circuit described in during charging mode.

[0032] Figure 8 shows an embodiment according to the present invention Figure 6 and Figure 7 The current path of the circuit described in FIG. 1 during the discharge mode (buffer mode).

[0033] Figure 9 Shown are periodic pulsed load current, battery current, and capacitor voltage as a function of time during charge mode and discharge mode according to an embodiment of the present invention.

[0034] Figure 10 A circuit for autonomous battery life enhancement according to another embodiment of the present invention is shown.

[0035] Figures 11a to 11d shows an embodiment according to the present invention Figure 10 The circuit described in the charging mode ( Figure 11a Depicts stage 1 of the charging mode, Figure 11b Depicts the stages of charge mode 2) and discharge mode ( Figure 11c Depicts stage 1 of the discharge pattern, Figure 11d The current path during phase 2) of the discharge mode is depicted.

[0036] Figure 12 A circuit for autonomous battery life enhancement according to another embodiment of the present invention is shown.

[0037] Figures 13a to 13d shows an embodiment according to the present invention Figure 12 The circuit described in the charging mode ( Figure 13a Depicts stage 1 of the charging mode, Figure 13b Depicts the stages of charge mode 2) and discharge mode ( Figure 13c Depicts stage 1 of the discharge pattern, Figure 13d The current path during phase 2) of the discharge mode is depicted.

[0038] Figure 14 A circuit for autonomous battery life enhancement according to another embodiment of the present invention is shown.

[0039] Figures 15a to 15d shows an embodiment according to the present invention Figure 12 The circuit described in the charging mode ( Figure 15a Depicts stage 1 of the charging mode, Figure 15b Depicts the stages of charge mode 2) and discharge mode ( Figure 15c Depicts stage 1 of the discharge pattern, Figure 15d The current path during phase 2) of the discharge mode is depicted.

[0040] Figure 16 A circuit for autonomous battery life enhancement according to another embodiment of the present invention is shown.

[0041] Figure 17A complete implementation of a circuit for autonomous battery life enhancement according to another embodiment of the present invention is shown.

[0042] Figure 18 The voltage at the storage cap (V) during a load pulse is shown as a function of time for a new cell with low series resistance. CAP ), output voltage at the load (V OUT ) and the voltage at the functional endpoint (V FEP ).

[0043] Figure 19 The voltage at the storage capacitor (V) during a load pulse is shown as a function of time for a battery at the end of life with high series resistance. CAP ), output voltage at the load (V OUT ) and the voltage at the functional endpoint (V FEP ).

[0044] Figure 20 A circuit for autonomous battery life enhancement according to another embodiment of the present invention is shown.

[0045] Figure 21 A circuit for autonomous battery life enhancement according to another embodiment of the present invention is shown. DETAILED DESCRIPTION

[0046] It will be readily understood that the components of the embodiments generally described herein and illustrated in the accompanying drawings may be arranged and designed in a variety of different configurations. Therefore, the following more detailed description of various embodiments, as represented in the figures, is not intended to limit the scope of the present disclosure, but is merely representative of various embodiments. Although various aspects of the embodiments are presented in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0047] The described embodiments are to be considered in all respects as illustrative only and not restrictive. Therefore, the scope of the present disclosure is indicated by the appended claims rather than by this detailed description. All changes that fall within the meaning and scope of the equivalents of the claims are to be included within their scope.

[0048] References to features, advantages, or similar language throughout this specification do not imply that all features and advantages that can be achieved using the present disclosure are or are present in any single example of the present disclosure. Rather, language referencing features and advantages should be understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Thus, throughout this specification, discussions of features and advantages and similar language may, but do not necessarily, refer to the same example.

[0049] In addition, the features, advantages, and characteristics of the present disclosure can be combined in one or more embodiments in any suitable manner. Those skilled in the relevant art will recognize that, according to the description herein, the present disclosure can be put into practice without one or more specific features or advantages of a particular embodiment. In other cases, it can be recognized that in certain embodiments, additional features and advantages that may not be present in all embodiments of the present disclosure are provided. Throughout this specification, reference to "one embodiment," "embodiment," or similar language means that the specific features, structures, or characteristics described in conjunction with the indicated embodiment are included in at least one embodiment of the present disclosure. Therefore, throughout this specification, phrases "in one embodiment," "in an embodiment," and similar language may, but do not necessarily, refer to the same embodiment.

[0050] As used above and throughout this application, a pulsed load current is a periodic (ie, repetitive) electromagnetic pulse having a predetermined amplitude and a pulse period that is longer than the time taken to charge a capacitor.

[0051] Figure 6 A circuit (100) for autonomous battery life enhancement according to an embodiment of the present invention is shown. The entire circuit (100) may have at least one power supply (300) in the form of, for example, a capacitor C BAT (320) is connected in parallel with the battery (310). Capacitor (320) is necessary when a switching converter is used to implement the charging module. The switching DC-DC converter extracts high frequency discontinuous current from the battery. Capacitor (320) is used to create a low pass filter so that the battery current is the average value of the discontinuous current used to charge the capacitor. The power supply (300) is connected to at least one output (600) in Figure 6 In the figure, the load current (610)I LOAD or output capacitor (620)C OUT At least one power source (300) and at least one output (600) are electrically connected in series to form an electrical load. The current sensing device (500) can be placed in the path of the load. The electrical connection can be achieved using wires.

[0052] The DC-DC converter (200) is electrically connected at two locations (110, 120) on the load and is positioned in parallel with the current sensing device (500), wherein the electrical connection is made at either side (or end) of the current sensing device (500) on the load. A first connection (110) is made so that charge from the battery is input to the DC-DC converter through the input module (240) to charge the capacitor (400). The voltage across this first connection (240) is a voltage having a battery discharge current I CHARGE The battery voltage V BAT(110). A second connection (120) is made so that the charge from the capacitor (400) is output to the load through the DC-DC converter (250). The voltage across this second connection is a voltage having an output current I OUT Load voltage V LOAD (120).

[0053] By placing the DC-DC converter (200) in parallel with the electrical load path between the battery (300) and the output (600), the overall power consumption of the circuit (100) can be reduced because the DC-DC converter (200) can be switched off for low loads while allowing the load to still flow between the battery (300) and the output (600).

[0054] The DC-DC converter (200) includes a controller (230) electrically connected to a current sensing device (500) on a load. The current sensing device (500) senses the current of the current sensing device (R SENSE , 500) the current I SENSE .

[0055] The DC-DC converter (200) further comprises a connection module (260), wherein the DC-DC converter (200) is connected to a capacitor C STORE and voltage V CAP A storage capacitor (400) is provided.

[0056] Figure 6 The DC-DC converter (200) further includes a buffer module (210) and a charging module (220). The charging module (220) is electrically connected between the input module (240) and the connection module (260) and is configured to transfer charge from the input module (240) to the connection module (260). The buffer module (210) is electrically connected between the connection module (260) and the output module (250) and is configured to transfer charge from the capacitor (400) to the load (600).

[0057] The controller (or controller module) of the DC-DC converter (200) is also configured to monitor and control the output current (I OUT ) and delivers it to the load. OUT Below threshold I STOP When the controller (230) is configured to instruct the buffer module (210) to stop transmitting current to the load and to instruct the charging module (220) to start charging the capacitor C STORE (400) (re)charge. The controller (230) is further configured to charge the capacitor (400) to a maximum voltage level V CAP,MAXInstruct the charging module (220) to stop charging. In addition, the controller module (230) and the current sensing module (500) can be manufactured as one module, but can also be separate modules.

[0058] Although Figure 6 Not shown, but the controller (230) is also connected to ground, battery voltage V BAT and the output voltage V LOAD .

[0059] As described below, the present invention is based on the capacitor C STORE (400) is much higher than the (sampled) battery voltage V BAT Energy storage is used at a voltage level of 10000. A DC-DC converter (200) is attached in parallel with the load current to charge the capacitor (400) using a constant low current from the battery (300). The magnitude of this current is so low that it can extend the life of the battery (300) by reducing the rate at which the voltage drops with each pulse cycle and reducing the rate at which internal resistance builds up in the battery (300).

[0060] The DC-DC converter (200) employs two modes of operation: a charging mode and a discharging mode, which are described below.

[0061] Charging mode

[0062] Figure 7 The charging mode performed by the circuit according to the embodiment of the present invention is shown. The charging mode refers to the battery charging the capacitor.

[0063] The controller (230) monitors and measures the no-load (sampled) battery voltage and the load current I flowing from the battery (310) to the current sensing module (500). SENSE When I SENSE (If the current sensing module is a resistor, then R SENSE ) is lower than the first threshold I START When the controller is configured to instruct the charging module (220) to charge the storage capacitor C STORE (400) is charged to prepare for the (next) high load pulse. The current path through the DC-DC converter (200) is Figure 7 In this mode, the battery charge is passed through the DC-DC converter (200) with a current I CHARGE is transferred to capacitor (400) until capacitor (400) is charged to the maximum voltage level V CAP,MAX Once this maximum voltage level is reached (or when the circuit (100) enters a discharge mode described below), the controller (230) instructs the charging module (220) to stop charging the storage capacitor (400).

[0064] Discharge mode

[0065] Figure 8 The discharge mode performed by the circuit (100) according to the embodiment of the present invention is shown. The discharge mode means that the capacitor (400) supplies charge to the load instead of the battery (310).

[0066] The controller (230) monitors and measures the no-load (sampled) battery voltage and the load current I flowing from the battery (310) to the current sensing module (500). SENSE When I SENSE (If the current sensing module (500) is a resistor, then R SENSE ) is higher than the first threshold I START When the controller (230) is configured to activate and instruct the buffer module (210) to use the DC-DC converter (200) to transfer the current from C STORE (400) is supplied to the load, where the output voltage V LOAD (120) At current I OUT The current path through the DC-DC converter (200) is regulated to the no-load (sampled) battery voltage. This process is also called buffering. Figure 8 This results in the battery (310) (or power supply 300) no longer discharging and the load current I LOAD (610) output, load current I LOAD is delivered entirely (or primarily) by the storage capacitor (400) connected to the DC-DC converter (200). In other words, V LOAD (120) is regulated to V BAT (110) (i.e., V LOAD =V BAT ). In other words, I SENSE is regulated to zero, so that almost no current is drawn from the battery (310) (i.e., I LOAD =I OUT ).

[0067] The controller (200) is further configured to monitor the output current I of the buffer (210) delivered to the load. OUT . When I OUT Below the second threshold I STOP , the controller (230) will stop the buffer (210) and will enter the above-mentioned charging mode.

[0068] Figure 9 shows the load current I LOAD , capacitor voltage V CAP , and battery (310) (power supply 300) current IBAT Initially, the DC-DC converter (200) is idle and the battery (310) is charged by a current having R SENSE The current sensing module (500) supplies current I to the load LOAD Here, the idle DC-DC converter (200) means I LOAD Less than threshold I START At time T1, through R SENSE The current I SENSE Above threshold I START , and the controller (230) is configured to activate (or instruct) the buffer (210), and the full load current I LOAD The buffer (210) current I OUT supply. In this case, V LOAD (120) is regulated to the (sampled) battery voltage V BAT (110), so that almost no current is drawn from the battery (310), and when the current from the capacitor (mainly or completely) replaces the current supplied by the battery to the load, during the buffering process, V BAT There is no discernible change in (i.e., no voltage drop). The capacitor voltage V CAP As the capacitor (400) now supplies the current I with the charge Q held in the capacitor (400) LOAD This controller (230) monitors I OUT , and once I OUT Below I STOP , then at time T2 the buffer (210) is disabled and the charging circuit (220) is enabled to charge C with charge Q from time T2 to T3. STORE (400) recharge to voltage V CAP,MAX Once the charging process is complete, the DC-DC converter (200) returns to idle. By defining I STOP START , use hysteresis to prevent oscillation.

[0069] The advantage of charging the capacitor (400) to a voltage higher than the (sampled) battery voltage is that the amount of energy stored in the capacitor (400) is proportional to the square of the voltage. Charging up to 4 times the battery voltage stores 16 times the energy of using the same capacitor for battery decoupling.

[0070] The advantage of discharging the battery (310) only between load current pulses to charge the storage capacitor is that the maximum battery capacitance is obtained and no voltage drop occurs during the load pulses, thereby achieving maximum battery life. For a given load current profile, this method gives the best possible battery discharge current profile. ​

[0071] If the storage capacitor is not fully charged (i.e., not charged to V CAP,MAX ), the charging mode may be interrupted and restarted after the load current pulse is delivered. This results in insufficient charge being drawn from the capacitor because it is not fully charged. To prevent this, the storage capacitor may also have a minimum voltage level V CAP,MIN , so that the controller is configured to discharge the capacitor from V CAP,MAX Discharge to V CAP,MIN (instead of 0) to prevent the charge in the capacitor from being depleted

[0072] Return to Figure 6 The DC-DC converter (200) may further include a second current sensing module (510) configured to sense the output current (I OUT ), and can be configured to end the discharge (buffer) phase when the output current drops below a threshold. This allows the circuit (100) to switch autonomously between the charging mode and the discharging mode, and the circuit (100) is able to determine the timing of switching to the charging mode and the discharging mode. This means that the circuit does not require any additional circuitry, such as I 2 C / SPI bus to perform these functions.

[0073] In the following, different configurations of DC-DC converters are disclosed.

[0074] Variant 1: Non-inverting DC-DC Converter

[0075] Figure 10 A circuit (100) for autonomous battery life enhancement according to an embodiment of the present invention is shown. In this embodiment, the DC-DC converter (100) is implemented as a non-inverting (inductive) DC-DC converter, which includes an inductor L (600) and switches S1-S5, wherein the inductor (600) and the switches serve as a buffer (210) and a charging (220) module. In this variant, the charging module (220) is a combination of the inductor (600) and switches S1, S2, S4 and S5, and the buffer module (210) is a combination of the inductor (600) and switches S2, S3, S4 and S5. The input module (240) of the DC-DC converter (200) is connected to the switch S1, the output module (250) of the DC-DC converter (200) is connected to the switch S3, and the connector module (260) of the DC-DC converter (200) is connected to the switch S2. The remaining aspects of the circuit (100) are the same as those of the above embodiments and Figures 6 to 8 These are the same as those described in , so for the sake of brevity they are not discussed here.

[0076] It should be understood that non-inverting refers to the capacitor voltage V CAP The positive polarity of means that the capacitor (400) has a positive capacitor voltage relative to ground.

[0077] During the charging mode, the controller (230) discharges the battery current I BAT (As I CHARGE ) is adjusted to a predetermined value. This is achieved by controlling the DC-DC converter (200) in a discontinuous buck-boost mode as described below. Although the present invention is described below with respect to the discontinuous buck-boost mode, other mode variations exist. These other modes are well known in the art, and a skilled person will understand the differences between these modes.

[0078] The charging mode occurs in three phases that repeat at a switching frequency fs. The charging current is equal to the time-averaged current from the battery to the inductor during the three phases of each switching cycle. During the charging mode, the battery (310) is charged with a (low) load current I LOAD、 and the charging current I from the battery (310) through the DC-DC converter (200) to the capacitor (400) CHARGE discharge.

[0079] Described below Figures 11a to 11d Disclosed in the use of Figure 10 Current through the DC-DC converter (200) during charge and discharge modes of the same circuit system.

[0080] Figure 11a Phase 1 of the charging mode is shown, where switches S1 and S5 in the DC-DC converter (200) are closed, causing current to flow from the input module of the DC-DC converter (200) to the inductor L (500). This allows current to flow through the inductor (600) I L The current to ground increases linearly.

[0081] Figure 11b Phase 2 of the charging mode is shown, where switches S1 and S5 in the DC-DC converter (200) are open and switches S2 and S4 are closed. The inductor current I accumulated in phase 1 of the charging mode L Now the current flows from ground to the storage capacitor (400), and to the capacitor C STORE (400) is charged. From ground, through inductor L (600) to C STORE (400) current I L will gradually decrease over time until it reaches zero.

[0082] In phase 3 of the charging mode, switches S2 and S4 are opened, causing all switches to be open and the switch (S1-S5) configuration to return to Figure 10 The configuration shown in . The inductor (600) current remains zero and the circuit (100) does nothing until phase 1 of the charging mode restarts. The length of phase 3 depends on the capacitor voltage V CAP , (sampled) battery voltage V BAT , switching frequency fs, length of phase 1 of the charging mode and inductor value L. When all parameters are chosen appropriately, the length of phase 3 of the charging phase is always above zero and the charging current is independent of the capacitor voltage and depends only on fs, V BAT , L and the length of phase 1 of the charging mode.

[0083] During the discharge mode, the current sensing module (500) R SENSE The voltage across the terminals is regulated to zero, and the output voltage is regulated to the no-load (sampled) battery voltage. Regulation of the DC-DC converter (200) is accomplished by controlling the timing of the switches (S1-S5) using various methods known in the art, such as buck, boost, and buck-boost control. Each of these methods can operate in continuous conduction mode (CCM), which uses two phases, and discontinuous conduction mode (DCM), which also uses a third (idle) phase.

[0084] Buck mode can only be used when the capacitor voltage is higher than the load voltage. Boost mode can only be used when the capacitor voltage is lower than the load voltage. Buck-boost mode can be used when the capacitor voltage is lower or higher than the load voltage.

[0085] As an example, a buck-boost mode is described herein that allows the capacitor voltage to be both above and below the load voltage. A discharge mode also occurs in three phases, where the length of phase 3 of the discharge mode depends on the load current and can be zero for high load currents (CCM) or non-zero for low load currents (DCM). During phase 1 of the discharge mode, the storage capacitor (400) is discharging to provide the load current and the battery current is close to (if not equal to) zero.

[0086] Figure 11c Phase 1 of the discharge mode is shown, where switches S2 and S4 are closed and the current I L From C STORE (400) flows through the inductor (600) to ground and will increase linearly.

[0087] Figure 11d Phase 2 of the discharge mode is shown, where switches S2 and S4 are open, and switches S3 and S5 are closed, so that the current I through the inductor L (600) is LWhen the next switching cycle starts a new phase 1 of the discharge mode (for CCM), or when I L Phase 2 of the discharge mode ends when the current has reached approximately zero (for DCM) and phase 3 of the discharge mode begins. During phase 2 of the discharge mode, the storage capacitor (400) is not discharged, but the load current is still carried by the inductor (600) and the output capacitor C OUT provided, and the battery current remains close to (if not equal to) zero.

[0088] In phase 3 of the discharge mode, all switches (S1-S5) are turned off and the switch (S1-S5) configuration is restored to Figure 10 The configuration shown in , and the circuit (100) can be idle until the next switching cycle begins.

[0089] Variant 2: Inverting DC-DC Converter

[0090] Figure 12 A circuit for autonomous battery life enhancement according to another embodiment of the present invention is shown. In this embodiment, the DC-DC converter (200) is implemented as an inverting (inductive) DC-DC converter, which includes an inductor L (600) (connected to the DC-DC converter (200) at a connection point LX) and switches S1-S3, wherein the inductor (600) and the switches serve as a buffer (210) and a charging (220) module. In this variant, the charging module (220) is a combination of the inductor (600) and switches S1 and S2, and the buffer module (210) is a combination of the inductor (600) and switches S2 and S3. The input module (240) of the DC-DC converter (200) is connected to the switch S1, the output module (250) of the DC-DC converter (200) is connected to the switch S3, and the connector module (260) of the DC-DC converter (200) is connected to the switch S2. The remaining aspects of the circuit are the same as those of the above embodiments and Figures 6 to 8 and Figure 10 to Figure 1 1, so for the sake of brevity, they are not discussed here again. It should be understood that the reverse phase refers to the capacitor voltage V CAP The negative (or reverse) polarity of the inductor means that the capacitor (400) has a negative capacitor voltage relative to ground. The benefit of the negative polarity is that it reduces the number of switches in the DC-DC converter. An additional benefit is that one side of the inductor is directly connected to ground and the DC-DC converter requires two fewer pins to connect to it.

[0091] Described below Figures 13a to 13d Disclosed in the use of Figure 12 Current through the DC-DC converter (200) during charge and discharge modes of the same circuit system.

[0092] Figure 13a Phase 1 of the charging mode is shown, where only switch S1 is closed (switches S2 and S3 are open), and current travels from the input module (240) through the inductor via connection LX in the DC-DC converter (200) to ground.

[0093] Figure 13b Phase 2 of the charging mode is shown, wherein switch S1 is open and switch S2 is closed, causing current to flow from ground through a capacitor (400) connected to a connection module (260) of a DC-DC converter (200) through an inductor (600) and back to ground. Figure 13b Indicated as a dotted line in FIG, and the current path for charging the capacitor (400) using this phase. In phase 3, all switches S1-S3 are opened, and the switch (S1-S3) configuration is restored to Figure 12 The configuration shown in .

[0094] Figure 13c Phase 1 of the discharge mode is shown, where switch S2 is closed and current travels from the capacitor through the inductor to ground and back to the capacitor

[0095] Figure 13d Phase 2 of the discharge mode is shown, where switch S2 is open and switch S3 is closed, causing current to flow from ground through the inductor (600) through the output module (250) of the DC-DC converter (200) to the load. In phase 3, all switches are open and the switch (S1-S3) configuration is restored to Figure 12 The configuration shown in .

[0096] Instead of connecting the inductor (600) to an external ground, the connection can be made through the DC-DC converter (200). Since the inductor current always flows to ground, this allows for easy implementation of a ground referenced current sensing circuit.

[0097] Compared to the non-inverting DC-DC converter (200) of variant 1 above, this inverting DC-DC converter (200) has several advantages. Only three switches (S1-S3) are required to perform DC-DC conversion because one side of the inductor (600) is permanently connected to ground. This reduces system complexity and reduces cost. For an integrated DC-DC converter (200), this results in a smaller die size (lower cost) or lower power loss (higher power efficiency) when the same area is used for fewer switches. Switch S2 and the inductor (600) are now time-shared between charging mode and discharging mode (buffer phase). Only one inductor (600) is connected to switch between the battery voltage, the capacitor voltage, and the output voltage. This is beneficial for electromagnetic coupling (EMC) behavior in printed circuit board (PCB) design. Since one terminal of the inductor is always connected to ground, all inductor current measurements required for charging mode and discharging mode can be completed in a single ground connection, rather than measuring the current through different switches. This allows for easier implementation using a single measurement circuit relative to ground that can provide all the information needed for peak current detection, zero current, etc.

[0098] Variant 3: Inverting DC-DC Converter

[0099] Figure 14 A circuit (100) for autonomous battery life enhancement according to another embodiment of the present invention is shown. In this embodiment, the DC-DC converter (200) is implemented as an inverting (inductive) DC-DC converter (200) that allows power to flow in both directions. The DC-DC converter (200) includes an inductor L (600, connected to the DC-DC converter (200) at a connection point LX) and switches S1 and S2, wherein the inductor (600) and switches (S1, S2) serve as both a buffer (210) and a charging (220) module. In this variation, both the charging module (220) and the buffer module (210) are a combination of the same inductor (600) and switches S1 and S2. The difference between the charging mode of operation and the discharging mode of operation is implemented in the different timing and control of the switches (S1, S2). The input module (240) of the DC-DC converter (200) is connected to the switch S1, the output module (250) of the DC-DC converter shares the same circuit as the input module (240) (i.e., is also connected to the switch S1), and the connector module (260) of the DC-DC converter (200) is connected to the switch S2. The rest of the circuit is the same as the above embodiment and Figures 6 to 8 Same as those described in Figures 11 to 13. It should be understood that the reverse phase refers to the capacitor voltage V CAPThe negative (or reverse) polarity of means that the capacitor (400) has a negative capacitor voltage with respect to ground.

[0100] Described below Figures 15a to 15d Disclosed in the use of Figure 14 Current through a DC-DC converter (200) during charging and discharging modes of the same circuit system.

[0101] Figure 15a Phase 1 of the charging mode is shown, where switch S1 is closed (switch S2 is open), and current travels from the input module (240) through the inductor (600) to ground.

[0102] Figure 15b Phase 2 of the charging mode is shown, wherein switch S1 is open and switch S2 is closed, causing current to flow from ground through the inductor (600) to the capacitor (400) of the connection module (260) connected to the DC-DC converter (200) and back to ground. In phase 3, both switches S1 and S2 are opened, and the switch (S1-S2) configuration is restored to Figure 14 The configuration shown in .

[0103] Figure 15c Phase 1 of the discharge mode is shown, where switch S2 is closed and current travels from ground through inductor (600) to capacitor (400) back to ground.

[0104] Figure 15d Phase 2 of the discharge mode is shown, wherein switch S2 is open and switch S1 is closed, causing current to flow from ground through the inductor (600) through the output module (250) of the DC-DC converter (200), which is also the input module (240), to the load.

[0105] In this embodiment, the current for both charging and discharging is V BAT (110) is connected. This means that the output current flows through the current sensor module R SENSE (500). Therefore, the current sensor module (500) R SENSE The voltage across the terminals is not zero during the discharge mode. Advantageously, the current sensor module (500) R SENSE It can now also be used to detect when the current falls below I STOP In phase 3, all switches are opened and the switch (S1-S2) configuration is restored to Figure 14 The configuration shown in .

[0106] As in variation 2, the ground connection of the inductor (600) through the connection port LX through the DC-DC converter (200) can be made to easily implement a reference current sensing circuit.

[0107] In this embodiment, in order to prevent the battery (310) from delivering current during the discharge mode, the DC-DC converter (200) may also include a sample and hold module (270), such as Figure 16 As shown in FIG, it is configured to store the reference battery voltage V BAT,S&H During the charging mode (during low load current), the sample and hold module (270) is configured to store the battery voltage V sampled during the discharge mode for regulating BAT The reference battery voltage value is set so that all output current is provided by the capacitor (400) through the buffer module and prevents the battery (310) (or power supply 300) from delivering any current. SENSE ) voltage drop across the terminals, the voltage at the load is different from the sampled battery voltage. Current sensor module (500) R SENSE The internal resistance, which is much lower than that of the battery (310), does not degrade the overall performance of the circuit.

[0108] Variant 4: Fully implemented

[0109] Figure 17 A complete system for fully implementing the circuit as an autonomous battery booster is shown in FIG. Similar to other embodiments, the circuit (100) includes a battery (310), an output (200), a DC-DC converter (200), a current sensing module (500) (here depicted as a resistor R SENSE ), an inductor L (600) connected to the DC-DC converter (200) at two connection points (LX1, LX2), and a capacitor (400), similar to the above disclosure. The module with reference numeral 280 refers to a compartment of the DC-DC converter (200) that houses a switch that, in combination with the inductor L (600), operates as a charging module during a charging mode (based on input from the charging control module 221) and a discharging mode (based on input from the buffer control module 211). The DC-DC converter (200) may also include a comparator (271), which may function similarly to the sample and hold module (270).

[0110] Furthermore, the circuit (100) includes a reference circuit V that provides a voltage and current reference. REF (291), and a logic block (290) that uses the comparator signal to control all functions (such as a controller). The logic signal on the EN pin (292) is used to turn the entire circuit on and off. Since the load is always connected through R SENSE(500) is connected to the battery (310) so that everything can be switched off when no high load is expected. The logic signal on the RDY pin (293) indicates when the capacitor is fully charged to V CAP,MAX For pulsed load currents, and new cells with relatively high voltage and low internal resistance, this is Figure 18 As shown in. V CAP The changes occur with Figure 9 Once the pulse load I occurs when the capacitor (400) is fully charged LOAD (as indicated by the RDY pin (293) signal), the capacitor voltage drops to near the output voltage V OUT The buffer signal indicates that the DC-DC converter (200) is operating in the discharge mode. Thereafter, the voltage of the capacitor (400) (when it is charged) is increased by the battery (310) at a current I BAT increases, and the charging signal indicates that the DC-DC converter (200) is in charging mode. Figure 19 shows the voltage value of a battery (310) nearing the end of its life, where V OUT The functional end point (FEP) voltage V FEP .

[0111] When utilizing the circuit of the present invention, the total charge required by the load current pulse is perfectly distributed over time using a predetermined battery current level. This charging current level determines the time required to recharge the capacitor. During the load pulse, the output voltage remains close to the no-load sampled battery voltage level. Only during charging mode does the charging current multiplied by the battery's internal resistance cause the voltage to drop.

[0112] The battery (or power supply) current can be measured in different ways. SENSE The use of is just one way chosen to illustrate this approach. In order to match the load to the battery, the capacitor size and the maximum capacitor voltage must be chosen so that it contains enough energy to supply the load pulses. The charging current level must be chosen so that it can recharge the capacitor between load pulses. During incorrect operation, a wrong choice of component values ​​or too high a load current will degrade the overall system performance to that of a conventional decoupling system. If the capacitor is chosen too small, or the load current peak appears too high or too long, the capacitor voltage will drop below the minimum value and will then automatically recharge. Therefore, the remainder of the load current pulse will have to be supplied by the battery and the decoupling capacitor C BAT and C OUTIf the charging current is too low, the circuit will not be able to fully recharge the storage capacitor and the minimum capacitor voltage will be reached. Even if the battery voltage drops below the circuit's minimum supply voltage, the circuit will shut down, but the battery will still be connected to the load, so that shutting down the circuit will not lead to the end of the application's life.

[0113] Although only switches are mentioned above, it is well known in the art that the functions performed by switches in DC-DC converters can be easily performed by semiconductor diodes and field effect transistors (FETs) such as metal oxide semiconductor FETs (MOSFETs). These semiconductor diodes function in the same manner as the switches in the circuit (100) described in the above embodiments. For example, Figure 20 and Figure 21 Depicted separately Figure 12 and Figure 10 A circuit system wherein the switch S3 is replaced by a diode oriented such that the cathode of the diode points toward the output module (250).

[0114] The scope of the present disclosure includes any novel feature, or combination of features, or any generalization thereof, disclosed explicitly or implicitly therein, whether or not it relates to the claimed invention or alleviates any or all of the problems solved by the invention. The applicants hereby give notice that new claims may be formulated to such features during the prosecution of the present application or of any such further application derived therefrom.

[0115] In particular, with reference to the appended claims, features from the dependent claims may be combined with features from the independent claims, and features from the respective independent claims may be combined in any appropriate manner and not merely in the specific combinations enumerated in the claims.

[0116] Features that are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

[0117] The term "comprising" does not exclude other elements or steps, and the term "a" or "an" does not exclude a plurality. Reference signs in the claims should not be construed as limiting the scope of the claims.

Claims

1. A circuit for autonomous battery life enhancement, the circuit comprising -power supply; an output electrically connected to the power supply, said electrical connection forming an electrical load path, - a current sensing module located in the electrical load path between the power source and the output, a direct current (DC)-direct current (DC)-DC converter positioned in parallel with the current sensing module and the electrical load path and electrically connected to the electrical load path at both ends of the current sensing module, and - a capacitor electrically connected to the DC-DC converter, in -The DC-DC converter comprises: an input module electrically connected to the electrical load path between the power source and the current sensing module, the input module being configured to receive charge from the power source, an output module electrically connected to the electrical load path between the current sensing module and the output, configured to transfer charge from the capacitor, ○ a connection module, the connection module being connected to the capacitor, a charging module configured to connect the input module with the connection module, a buffer configured to connect the connection module with the output module, and a controller connected to the charging module, the buffer, and the current sensing module, Wherein, in operation, the controller is configured to ■ when the current sensed by the current sensing module is lower than a first threshold, instructing the charging module to transfer a first charge from the input module to the connection module to charge the capacitor, and ■When the current sensed by the current sensing module is higher than a first threshold, instruct the buffer to transfer a second charge from the capacitor connected to the connection module to the output module to replace the sensed current on the electric load path until the voltage of the capacitor reaches a threshold. 2 . The circuit of claim 1 , wherein the charging module comprises a first inductor and at least one switch, and the buffer comprises the first inductor and at least one switch. 3 . The circuit according to claim 2 , wherein the charging module and the buffer share at least one switch.

4. The circuit of any one of the preceding claims, wherein the DC-DC converter further comprises a sample and hold module configured to store a voltage from the power supply.

5. A circuit as claimed in any preceding claim, wherein the capacitor has a positive polarity, wherein the negative capacitor voltage is positive with respect to ground.

6. The circuit of any one of claims 1 to 4, wherein the capacitor has a negative polarity, wherein the capacitor voltage is negative with respect to ground.

7. The circuit of any preceding claim, wherein the current sensing means is a resistor.

8. A method of operating a circuit for autonomous battery life enhancement, the method comprising: (i) sensing the current in the electrical load path between the power supply and the output by a current sensing module, wherein (ii) when the sensed current is lower than a first threshold, a. transferring charge from the electrical load path to the input module of the DC-DC converter via a DC-DC converter controller, b. the controller and the DC-DC converter charging module transfer the charge from the input module to the DC-DC converter connection module, c. transferring the charge by the controller and the charging module to a capacitor connected to the connection module, and (iii) when the sensed current is higher than a first threshold, a. transferring charge from the capacitor to the connection module of the DC-DC converter by the controller and the buffer of the DC-DC converter until the voltage of the capacitor reaches a threshold value, b. transferring charge from the connection module of the DC-DC converter to the output module of the DC-DC converter by the controller and the buffer, c. Transferring, by the controller, charge from the output module to the electrical load path to an output at the sensed current level.

9. The method of claim 8, wherein in steps (ii)(b) and (iii)(b), the transferred charge passes through a first inductor of the DC-DC converter and at least one switch of the DC-DC converter.

10. The method of claim 9, wherein in steps (ii)(b) and (iii)(b), the transferred charge passes through at least one common switch.

11. The method according to any one of claims 7 to 9, wherein step (ii)(a) further comprises storing the voltage of the power supply in a sample and hold module in the DC-DC converter.

12. The method of claim 11, wherein in steps (ii)(b) and (iii)(b), the current passes through the same inductor and at least one switch.

13. A method according to any one of claims 7 to 12, wherein the charge in steps (ii)(b) and (iii)(b) is passed through ground of the DC-DC converter.

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