Battery balancing for multiple battery systems

Abstract

The closed loop control system actively adjusts the battery current paths of physically separated circuits such that the current of each of the circuits is substantially the same regardless of various system loads. The closed loop control system modulates the current path by modulating a high side transistor for individually limiting the current path of each battery or by modulating the output voltage of the DC / DC converter to individually boost the current path of each battery. The closed-loop control system is also designed to handle an undervoltage lock-out (UVLO) condition when one of the batteries is near empty, to tilt power balance in the event of existing battery charge mismatch to support system load bursts, and to turn off the circuit when system current draw is abnormally low. The tilt circuit also identifies and discharges the battery having the higher charge until the states of charge are substantially equal.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. application serial number 17 / 965,421 filed on October 13, 2022 and U.S. provisional application serial number 63 / 358,688 filed on July 6, 2022, the contents of both of which are incorporated herein by reference in their entirety. Technical Field

[0003] Examples described herein generally relate to battery systems for mobile electronic devices, and more particularly to battery balancing systems for balancing charging and discharging of a multi-battery system in a mobile electronic device. Background Art

[0004] Mobile electronic devices such as electronic eyeglass devices may have electronics disposed in physically separate portions of the device. For example, the electronic eyeglass device may have electronics, such as a circuit board and a battery, disposed in the temple or arm of the electronic eyeglass device. In such cases, the electronics and battery in the temple or arm are physically isolated by the front lens frame and may charge / discharge at different rates, which may lead to potential issues with the health, reliability, and safety of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Some non-limiting examples are shown in the drawings, in which:

[0006] Figure 1A is a block diagram of a mobile device having circuits that are physically separated from each other and powered separately;

[0007] Figure 1B is a side view of an example eyewear device including circuitry in an arm or temple thereof;

[0008] Figure 1C yes Figure 1B a top cross-sectional view of the optical components and electronics in a portion of the eyewear device shown;

[0009] Figure 2 According to some examples Figures 1A-1C The current flow in the system, wherein the load on the left side of the electronic eyewear device is dominant;

[0010] Figure 3 is a block diagram of a power management system including a current balancing control loop that actively adjusts a battery current path so that current in the circuit on each side based on the load is approximately the same, according to some examples;

[0011] Figure 4Based on some examples including Figure 3 A block diagram of a power management system for a current balancing control loop of a power management system, the current balancing control loop being modified to include a tilting circuit;

[0012] Figure 5 Based on some examples including Figure 3 A block diagram of a power management system for a current balancing control loop of a power supply circuit, the current balancing control loop being modified to include an undervoltage lockout (UVLO) circuit control loop;

[0013] Figure 6 is a block diagram of a power management system including a disabling circuit for disabling all functions during periods of abnormally high or low load power consumption according to some examples;

[0014] Figure 7 Based on some examples including Figure 3 A block diagram of a power management system having a current balancing control loop modified to disable a set of cell balancing features for a single side when one side is predicted to have a dominant load;

[0015] Figure 8 Yes Figure 3-7 A block diagram of a power management system combining the features of the power management system in one circuit diagram;

[0016] Fig.9A Shown for reference Figure 8 Describes the state machine of the current balancing control loop for different operation modes of cell balancing;

[0017] Fig. 9B Shows Figure 4 a state machine for different operating modes of a battery tilt feature; and

[0018] Fig.10 is a block diagram of a power management system including a boost converter circuit that boosts the battery voltage alone, rather than Figure 3 -9 to limit the battery voltage. DETAILED DESCRIPTION

[0019] Circuits in a mobile device may have different loads that are powered by different batteries that operate separately, even if the circuits are part of the same system that provides various functions for the mobile device. For example, a main processor may be located on one side of the electronic eyewear device and consume power according to its load, while a coprocessor may be located on the other side of the electronic eyewear device and turned on / off separately. In addition, due to the resistance between the left and right sides of the electronic eyewear device, the current supplied by the battery on the corresponding side of the glasses can vary. This arrangement poses a problem because the batteries of physically displaced electronic devices in the mobile electronic device need to be charged and discharged substantially equally to avoid potential problems with battery health, reliability, and safety. In addition, while short-term mismatches or minor mismatches may be acceptable, long-term mismatches and severe errors are unacceptable.

[0020] Mobile electronic devices such as electronic eyewear devices may use multiple boards and batteries in various parts of the device to optimize space, heat dissipation, etc. To ensure good battery health, it is desirable to charge and discharge all batteries used in such a device at substantially the same rate. This becomes challenging because system loads change dynamically and can become unbalanced, coupled with the additional resistance introduced by physical separation. The circuit described in this article measures and modulates the individual battery current paths in order to actively balance their discharge currents.

[0021] The circuit described in this article measures the current on the high side of the battery and feeds the measured current into a closed-loop control system. The closed-loop control system actively adjusts the battery current paths of physically separated circuits so that the current of each circuit is approximately the same, regardless of the various system loads. The closed-loop control system modulates the current path by modulating the high-side transistor used to individually limit the current path of each battery or by modulating the output voltage of the DC / DC converter to individually boost the voltage in the current path of each battery. The closed-loop control system is also designed to prevent undervoltage lockout (UVLO) conditions when one of the batteries is close to empty, adjust power balancing when there is an existing battery charge mismatch, and shut down the circuit when the system current draw is abnormally low. The tilting circuit can also identify and discharge the battery with a higher charge until the charge state of the batteries is substantially equal.

[0022] Therefore, the methods and systems described herein relate to a device including physically separated circuits, each of which includes a battery, a load, and a resistance along a current path to the load. The device (e.g., an electronic eyewear device having circuits in corresponding temples or arms separated by a frame) includes a battery balancing control loop that balances the battery charge of each circuit. The battery balancing control loop includes a current measurement circuit (e.g., a current sensing amplifier) ​​that measures the current through the circuit resistance, at least one differential amplifier that compares the measured current to generate an adjustment signal, and a current modulation device for modulating the current in the current path between the battery and the load in response to the adjustment signal. The current modulation device modulates a first current in a first current path of a first circuit by at least one of: (a) increasing the resistance in the first current path or reducing the battery voltage therein, or (b) increasing the battery voltage in the first current path or reducing the resistance therein. The current modulation device can similarly modulate a second current in a second current path of a second circuit.

[0023] The current modulation device may include a transistor in a first current path of the first circuit, the transistor dynamically limiting the first current in the first current path by adjusting the first resistance in the first current path in response to the adjustment signal until the first current in the first current path and the second current in the second current path are substantially the same. Alternatively, the current modulation device may include a DC / DC converter that increases the current in the first current path in response to the adjustment signal to balance the first current and the second current. The battery balancing control loop may also include a tilting circuit that checks the charge state of the first battery and the second battery to determine the charge mismatch and discharges the battery with a higher charge until the charge state of the batteries is substantially equal. The tilting circuit may include one or more transistors in the current path that, when activated, cause the current in the current path to be smaller. The battery balancing control loop may also include an undervoltage lockout control loop that adjusts the battery voltage of the circuit to above the undervoltage lockout point. The undervoltage lockout control loop may include a comparator in each circuit that compares the voltage applied to the load with a reference voltage, and when the voltage applied to the load is lower than the reference voltage, the comparator triggers the current modulation device to override its current modulation and add current to the current path.

[0024] A detailed description will now be provided with reference to Figures 1-10. Although this specification provides a detailed description of possible implementations, it should be noted that these details are exemplary only and in no way limit the scope of the inventive subject matter. For example, although the following description is about physically separated circuits in the temples or arms of electronic eyewear devices, it should be understood that the circuits and techniques described herein can be applied to any electronic device with circuits having different battery sources.

[0025] In an example configuration, the power management system described herein may be used in a mobile device that includes physically separate circuits that are powered by different batteries. Figure 1A is a block diagram of a mobile device having circuits 110 and 120 that are physically separated from each other and powered separately. As an example, Figure 1B and 1C The electronic eyewear device 100 is shown having electronic circuits 110 and 120 in the respective temples or arms.

[0026] Figure 1B 1 is a diagram depicting a side view of an example hardware configuration of a mobile device in the form of an eyeglass device 100, the eyeglass device 100 including an optical accessory 130 for each eye, each optical accessory including an image display 135 and a visible light camera 140 that forms a stereo camera together with the visible light camera for the other eye. Visible light camera 140 is located on the right temple 150 of the eyeglass device 100, and a second visible light camera is located on the left temple of the eyeglass device 100. In the example shown, optical accessory 130 is located on the right side of the eyeglass device 100. Optical accessory 130 may also be located on the left side of the eyeglass device 100 or at other locations.

[0027] The visible light camera 140 of each optical assembly 130 may include an image sensor that is sensitive to wavelengths in the visible light range. Each visible light camera 140 has a different coverage angle facing forward. The coverage angle is the angular range in which the corresponding image sensor of the visible light camera 140 detects incident light and generates image data. Examples of such visible light cameras 140 include high-resolution complementary metal oxide semiconductor (CMOS) image sensors and video graphics array (VGA) cameras, such as 640p (e.g., 640x480 pixels, a total of 300,000 pixels), 720p, 1080p, 4K, or 8K. The image sensor data from the visible light camera 140 can be captured along with the geolocation data, digitized by the image processor, and stored in a memory.

[0028] To provide stereoscopic vision, the visible light camera 140 may be coupled to an image processor (not shown) for digital processing and adding a timestamp corresponding to the scene of the captured image. The image processor may include circuitry for receiving signals from the visible light camera 140 and processing these signals from the visible light camera 140 into a format suitable for storage in a memory. The timestamp may be added by an image processor or other processor controlling the operation of the visible light camera 140. The visible light camera 140 allows the stereo camera to simulate human binocular vision. The stereo camera also provides the ability to reproduce a three-dimensional image of a three-dimensional scene based on two captured images with the same timestamp from the visible light camera 140, respectively. Such a three-dimensional image allows for a realistic immersive virtual experience, such as for virtual reality or video games. For stereoscopic vision, a pair of images may be generated at a given moment in time—one image for each of the visible light cameras 140 of each optical accessory 130 for each eye. When a pair of generated images of the forward-facing field of view (FOV) from the visible light camera 140 are stitched together (e.g., by an image processor), the optical accessory 130 provides depth perception for each eye.

[0029] In an example, the eyeglass device 100 includes a frame 160, a right edge 170, a right temple 150 extending from a right lateral side 180 of the frame 160, and a transparent image display 135, which includes an optical accessory 130 for presenting a graphical user interface (GUI) or other image to a user. The eyeglass device 100 includes a first visible light camera 140 connected to the frame 160 or the right temple 150 to capture a first image of a scene. The eyeglass device 100 also includes a second visible light camera (not shown) connected to the frame 160 or the left temple (not shown) to capture a second image of the scene (e.g., simultaneously with the first visible light camera 140), the second image at least partially overlapping the first image. Although Figure 1B Not shown in the figure, the image processor is coupled to the eyeglass device 100 and is connected to the visible light camera 140 and a memory accessible to the processor, and the programming in the memory may be provided in the eyeglass device 100 itself.

[0030] although Figure 1B , but the eyeglass device 100 may also include a head motion tracker ( Figure 1C The eyewear device 100 is configured by the processor to execute programming to perform functions, including the function of presenting an initial display image of the displayed image sequence via the perspective image display 135, the initial display image having an initial field of view corresponding to the initial head direction or initial eye gaze direction determined by the eye movement tracker.

[0031] Figure 1C yes Figure 1B A top cross-sectional view of the optical components and electronics in a portion of the eyeglass device shown, depicting a first visible light camera 140, a head motion tracker 190, and a circuit board 145. The second visible light camera is substantially similar in construction and placement to the first visible light camera 140, except that it is connected and coupled to the other lateral side of the eyeglass device 100. As shown, the eyeglass device 100 includes the first visible light camera 140 and the circuit board 145, which can be a flexible printed circuit board. The hinge 155 connects the right temple 150 to the articulated arm 165 of the eyeglass device 100. In some examples, the first visible light camera 140, the flexible PCB 145, or other components of the electrical connector or contact can be located on the right temple 150 or the hinge 155.

[0032] like Figure 1C As shown, the right temple includes a temple body 175 configured to receive a temple cap. Figure 1C Disposed within right temple 150 are various interconnected circuit boards, such as a PCB or flexible PCB 145, which include controller circuitry for visible light camera 145, one or more microphones 185, one or more speakers 195, low power wireless circuitry (e.g., for communicating with the user via a wireless controller), and a plurality of other circuits. Wireless short-range network communications), high-speed wireless circuits (such as for for wireless LAN communications) and power supply.

[0033] The first visible light camera 140 is coupled to or disposed on the flexible PCB 145 and is covered by a visible light camera cover lens that is aimed through one or more openings formed in the right temple 150. In some examples, the frame 160 connected to the right temple 150 includes one or more openings for the visible light camera cover lens. The frame 160 may include a front-facing side configured to face outward away from the user's eyes. The opening for the visible light camera cover lens may be formed on the front-facing side and through the front-facing side. In this example, the visible light camera 140 has an outward coverage angle with the line of sight or viewing angle of the right eye of the user of the eyeglass device 100. The visible light camera cover lens may also be adhered to the outward-facing surface of the right temple 150, forming an opening with an outward coverage angle therein, but in a different outward direction. Coupling may also be achieved indirectly via an intermediate component.

[0034] Flexible PCB 145 may be disposed within right temple 150 and coupled to one or more other components housed in right temple 150. Although shown as being formed on circuit board 145 of right temple 150, visible light camera 140 may be formed on another circuit board (not shown) in one of left temple, articulated arm 155, articulated arm 165, or frame 160.

[0035] like Figure 1A As shown, the circuit 110 in the left temple or arm of the electronic eyeglass device 100 can be generally represented as a battery 112, a charger 114, a temple resistor 116, and a load 118. Similarly, the circuit 120 in the right temple 150 or temple 165 of the electronic eyeglass device 100 can be generally represented as a battery 122, a charger 124, a temple resistor 126, and a load 128. The circuit 110 and the right circuit 120 are physically separated by the frame 160 of the glasses, which is Figure 1A It is represented as frame resistance 160.

[0036] Figure 2 Shows Figure 1A 2, wherein the load 118 in the circuit 110 in the left temple or arm of the electronic eyeglass device 100 dominates. In this case, the load 118 draws a large current from the battery 112 as shown by arrow 200, and also draws some current from the battery 122 of the circuit 120 in the right temple or arm as shown by arrow 210. Such current drawn by the load 118 causes a mismatch between the discharge rates of the batteries 112 and 122.

[0037] The following will refer to Figure 3-10 Different options for addressing this mismatch between the discharge rates of batteries 112 and 122 are described. These configurations reduce (or substantially minimize) the discharge mismatch by increasing resistance or decreasing the battery voltage on the side of the electronic eyeglass device 100 that experiences the higher battery discharge rate, increasing the voltage or decreasing the resistance on the other side of the electronic eyeglass device 100 to balance the load, or both. In other words, using Ohm's Law I=V / R, the current I on one side of the electronic eyeglass device 100 can be reduced by decreasing the voltage V, by increasing the resistance R, or both, and the current I on one side of the electronic eyeglass device 100 can be increased by increasing the voltage V, by decreasing the resistance R, or both, to properly balance the load on the corresponding side of the electronic eyeglass device 100. About Figure 3-10 The described circuit is used to continuously match the DC current provided by batteries 112 and 122 to improve battery health, reliability and safety. The described techniques are implemented with minimal software interaction and reduced circuit design complexity.

[0038] In the circuit configuration described herein, the high-side current of each battery on the respective side of the electronic eyewear device 100 is measured and fed into a closed-loop control system that performs the following functions, including:

[0039] - Actively adjust the battery current path so that the battery current is approximately the same on each side based on the load ( Figure 3 );

[0040] - If there is an existing battery discharge mismatch, the balance between the tilt circuits ( Figure 4 );

[0041] - Manages UVLO conditions when either battery is nearly empty (almost fully discharged) Figure 5 );

[0042] - Disables functionality when system current is abnormally high (i.e., above an upper threshold), and shuts down the circuit when system current is extremely low (i.e., below a lower threshold) ( Figure 6 );and

[0043] -Disable the cell balancing feature set for one side when one side is predicted to have the dominant load ( Figure 7 ).

[0044] By modulating the transistors used to individually limit the current in the left / right battery current paths ( Figure 3 -9), or by modulating the voltage output of a DC / DC converter (e.g., a boost circuit) to increase the current in the left / right battery slots individually ( Fig.10 ), to modulate the battery current path to achieve balanced current. Each of these configurations is described below.

[0045] Figure 3 is a block diagram of a power management system including a current balancing control loop 300 including elements 310 in circuit 110 L ,320 L and 330 L and the element 310 in the circuit 120 R ,320 R and 330 R , these components actively adjust the battery current paths of circuits 110 and 120 so that the currents through circuits 110 and 120 are substantially equal. The currents through circuits 110 and 120 vary according to the respective loads 118 and 128 in circuits 110 and 120. As shown, circuit 110 (120) includes a current sense amplifier (CSA) 310 that measures the current through resistor 116 (126). L (310 R ). CSA 310 L (310 R ) is provided to the differential amplifier 320 L (320 R ), based on the difference in the measured currents, via circuit 330 L (330 R ) provides a regulation signal. As shown in the figure, circuit 330 L Including power field effect transistor (PFET) 332 L, forward diode 334 L and resistor 336 L and 338 L , and the circuit 330 R Including PFET 332 R , forward diode 334 R and resistor 336 R and 338 R Specifically, the differential amplifier 320 L (320 R ) modulates the PFET 332 in the current path L (332 R ) to dynamically limit the current by dynamically adjusting the resistance. For example, when the circuit 310 L When “ON”, PFET 332 L (332 R ) is turned off and through PFET 332 L (332 R However, when a difference is detected between the measured currents through the temple resistors 116 and 126, the differential amplifier 320 L (320 R ) Modulation PFET 332 L (332 R ) to dynamically increase the resistance in the circuit 110 (120) with the larger measured current, thereby making the resistance and current on both sides of the electronic eyeglass device 100 consistent.

[0046] During operation, when the left circuit 110 has a dominant load, the PFET 332 on the side opposite to the dominant load R is turned on, and the PFET 332 on the dominant load side L The current is limited by adding resistance to match the other side. It should be recognized that there is an inherent offset (Delta_IBatt) in this solution. The inherent offset (Delta_IBatt) depends on the voltage (VBattery) of the batteries 112 and 122, the PFET 332 L and 332 R The voltage across both ends (Vth), the differential amplifier 320 L and 320 R Gain (AmpGain), differential amplifier 320 L and 320 R The voltage output (Amp Vos) and the corresponding tolerance. The response time is determined by the CSA 310 L and 310 R and a differential amplifier 320 L and 320R When loads 118 and 128 are very similar or equal, until Delta_IBatt, PFET 320 L and 320 R Both will be turned on, and above Delta_IBatt, the balancing provided by adding a resistor in circuit 110 or 120 will be effective.

[0047] Figure 4 is a block diagram of a power management system including a current balancing control loop 400, wherein Figure 3 The current balancing control loop 300 is modified to include a tilting circuit 410 L (including FET 412 L , reverse diode 414 L and resistor 416 L ) and 410 R (including FET 412 R , reverse diode 414 R and resistor 416 R ), they periodically check if there is any significant mismatch between batteries 112 and 122 and give priority to the lighter loaded side until the charges of batteries 112 and 122 are substantially balanced. During operation, CPU 420 L or 420 R The charge status of the batteries 112 and 122 provided by the chargers 114 and 124 may be checked periodically to determine any significant mismatch. If a mismatch exists, the TILT_FET 412 L or 412 R This will make the measured current through the corresponding temple resistor 116 or 126 appear to be smaller, thereby deceiving the CSA 310. L and 310 R , and causes the balancing circuit 330 L and 330 R Priority is given to the side with a higher state of charge. For example, if the left battery 112 is more discharged, the CPU 420 R Will turn on TILT_FFET 412 R , which will deceive CSA 310 L and 310 R It is believed that the current through the temple resistor 126 is lower than the current through the temple resistor 116, resulting in the differential amplifier 320 L Limiting by PFET332 L Once the charges of batteries 112 and 122 are substantially equal, CPU 420 RIt is determined that the charging state is balanced, and the enabled TILT_FET 412 R is turned off. The CPU 420 L can also appropriately perform these functions, or a single CPU 420 can be provided to perform these functions.

[0048] The tilt accuracy of the current balance control loop 400 depends on the tolerances of the measured resistances (Rds_on, Rsense, Rseries). For example, when Rsense = 10m, Rseries = 20m, and 7.3m < Rds_on < 12.6m, the tilt range is 23% - 27%.

[0049] Figure 5 is a block diagram of a power management system of a current balance control loop 300 including Figure 3 which is modified to include an under-voltage lockout (UVLO) circuit control loop 500 to adjust the battery voltages of circuits 110 and 120 above the UVLO point. As shown, a second control loop including a differential amplifier (comparator) 510 L and 510 R 、FET 520 L and 520 R 、diode 522 L and 522 R as well as resistors 512 L 、514 L 、512 R and 514 R is added to adjust the battery voltages of each of circuits 110 and 120 above the UVLO point. For the left circuit 110, the battery voltage is measured at the load 118 through resistors 512 L and 514 L and compared with a reference voltage (PP1V8) by the comparator 510 L . If the voltage is too low, the comparator 510 L will trigger the BATT_FET 520 L to turn on to pull down the gate of the PFET 332 L as needed, thus breaking the balance of the balance circuit 330 L and the tilt circuit 410 L ( Figure 4 ). If the resistance is too high, the current is increased instead of increasing the resistance to keep the circuit 110 active as much as possible. Limiting the peak load in this way reduces the voltage, thus temporarily providing a higher current. Using components 510 R 、520 R 、522 R 、512R and 514 R The same process is applied to the right circuit 120. Thus, the UVLO control loop 500 keeps the circuits 110 and 120 as active as possible.

[0050] It should be understood that, as with current balancing, the UVLO control loop 500 also has an inherent current mismatch. Fortunately, the UVLO point can be varied to add enough gain to provide balancing. For example, depending on the implementation, high / low thresholds can be set that are 5-10% of the minimum / maximum voltage. These thresholds can be controlled by a processor (such as CPU 420). L or 420 R ( Figure 4 )) is set. The response time is determined by the differential amplifier 510 L or 510 R The differential amplifier may be operated at, for example, 0.2 MHz and limited by any low pass filtering used to provide stability. The UVLO control loop 500 may also act as a balancing circuit 330. L On the other hand, UVLO control loop 500 intentionally adds mismatch to batteries 112 and 122.

[0051] Figure 6 6 is a block diagram of a power management circuit including a disable circuit 600 for disabling all features during periods of abnormally high or low load power consumption. During periods of abnormally high or low load power consumption, the CPU 420 L or 420 R At least one of the PFETs 332 may be turned on. L or PFET 332 R to close all control loops, disabling all features. In the high power case this will disable any battery current limiting, while in the low power case this will reduce standby power consumption. Thus, for abnormally low loads no balancing is required, while for abnormally high loads battery current limiting needs to be disabled.

[0052] In certain circuit implementations, it is easy to predict which circuit 110 or 120 will have the dominant load. Figure 7 Yes Figure 3 4 is a block diagram of a power management system for a current balancing control loop 300 of FIG. 40 that is modified to disable the battery balancing feature set of circuit 120 when it is predicted that circuit 110 will always have the dominant (peak) load. In this case, CPU 420 R (Not shown) the cell balancing feature set of circuit 120 may be disabled to reduce standby power consumption and improve control loop stability margin. Figure 7As shown, circuit 110 may maintain control loop characteristics 700 .

[0053] Figure 8 Yes Figure 3-7 The features of the power management system are combined in one circuit 800. Specifically, Figure 8 include Figure 3 Current balancing control loop 300, Figure 4 The tilt circuit 410, Figure 5 UVLO control loop 500, Figure 6 The disabling circuit 600 and Figure 7 A load mismatch circuit 700 is provided. Figure 8 Also included is a CPU 420 for controlling the tilt circuit 410 and the disable circuit 600 L and 420 R The operating mode of circuit 800 is determined by CPU 420 L and 420 R Based on state machine 810 L and 810 R Control, as shown below Fig.9A and 9B As described above, each CPU 420 L ,420 R Implementation.

[0054] For simplicity, CPU 420 L and 420 R Implemented state machine 810 L and 810 R can be divided into a state machine 900 for battery balancing ( Fig.9A ) and a state machine 950 for battery tilting ( Fig. 9B ). State machines 900 and 950 may be implemented by CPU 420 L and 420 R A separate low power microcontroller (not shown) controls. Fig.9A and 9B Use CPU 420 L and 420 R To demonstrate in an example the dynamic load can be operated independently on either side of the electronic eyewear device 100 .

[0055] Fig.9A Shown for reference Figure 8 The current balancing control loop 800 described above is a state machine 900 for different operation modes of battery balancing. As shown in the figure, when the CPU 420 L and 420 R When both are turned off, CPU 420 L With 420R In state 910, the battery balance is turned off. On the other hand, when the CPU 420 L and 420 R When both are turned on, CPU 420 L With 420 R In state 920, and battery balancing is turned on. When only the left CPU 420 L When turned on, CPU 420 L With 420 R In the left battery balance on state 930. Similarly, when only the right CPU 420 R When turned on, CPU 420 L With 420 R In the right cell balancing on state 940. The cell balancing feature is enabled accordingly.

[0056] Fig. 9B Shown for Figure 8 The state machine 950 of the tilting circuit 410 of the embodiment of the present invention is a state machine 950 for different operating modes of the battery tilting feature of the tilting circuit 410. According to the state machine 950, when the state of charge of one battery does not exceed 1.2 times the state of charge of the other battery, the battery tilting feature is turned off at state 960. When the state of charge of the left battery 112 exceeds 1.2 times the state of charge of the right battery 122, the left battery tilting function is turned on at state 970. Then, when the state of charge of the left battery 112 is less than 1.1 times the state of charge of the right battery 122 and the state machine returns to state 960, the left battery tilting feature is turned off. Similarly, when the state of charge of the right battery 122 exceeds 1.2 times the state of charge of the left battery 112, the right battery tilting feature is turned on at state 980. Then, when the state of charge of the right battery 122 is less than 1.1 times the state of charge of the left battery 112 and the state machine returns to state 960, the right battery tilting feature is turned off.

[0057] In an alternative configuration, the left or right battery voltage can be boosted individually, rather than as Figure 3 -9 configuration to limit the battery voltage. Fig.10 1 is a block diagram of a power management system including a boost converter circuit 1000 that boosts the left or right battery voltage individually, rather than Figure 3 -9 to limit the voltage. Fig.10 The boost converter circuit 1000 includes a boost circuit 1010 for a left circuit 110. L and a boost circuit 1010 for the right circuit 120 R Each boost circuit 1010 L and 1010 R Includes voltage regulation pin 1012 L or 1012R , which is used in response to the differential amplifier 320 L and 320 R Any voltage imbalance is measured while modulating the boost circuit 1010 L or 1010 R As shown in the figure, the boost converter circuit 1000 may include a FET 1020 L 、Diode 1022 L and resistor 1024 L , they provide boost circuit 1010 L Provide a voltage modulation signal, the voltage modulation signal is increased by adding a boost circuit 1010 L The boost converter circuit 1000 may further include a FET 1020. R 、Diode 1022 R and resistor 1024 R , they provide boost circuit 1010 R Provides a voltage modulation signal, which is increased by the boost circuit 1010 R The output voltage is used to increase the current applied to load 128 to match the current applied to load 118.

[0058] exist Fig.10 In the configuration, the differential amplifier 320 L and 320 R Modulation boost circuit 1010 L and 1010 R The voltage regulation pin 1012 L or 1012 R , to dynamically increase the voltage applied to the load 118 or 128. In the example configuration, the boost circuit 1010 L and 1010 R may be a DC / DC converter configured to respond to the voltage at the voltage adjustment pin 1012 L or 1012 R By boosting the voltage, any resistance 160 seen through the frame between the left temple circuit 110 and the right temple circuit 120 can be overcome.

[0059] It should be understood that Fig.10 The control loop method used in is inherently safe because it will never accidentally cut off the battery current path. Depending on the application, Fig.10 The control loop method used in can also be more efficient. It will be further understood that Fig.10The control loop method used in can better handle high power usage by boosting two batteries. L and 1010 R Higher Vin requirements, Fig.10 The control loop approach used in is also better suited to handle the UVLO use case.

[0060] However, it should be understood that since the boost circuit 1010 L and 1010 R The internal control loop of the DC / DC converter used in Fig.10 The control loop method used in can severely limit stability and response time. Therefore, depending on the application, Fig.10 The control loop method used in may also be inefficient. Figure 3-8 Compared with the configuration of Fig.10 The closed-loop approach used in may also have increased size and cost.

[0061] Those skilled in the art will appreciate that the circuits described herein may be analog or digital circuits. However, digital circuits may be more expensive and may require the use of software to implement the control loop, which may increase cost, complexity, and response time.

[0062] Although various embodiments have been described above, it should be understood that they are presented by way of example only and not limitation. For example, any element associated with the above-described systems and methods may employ any desired functionality described above. Therefore, the breadth and scope of the preferred embodiments should not be limited by any of the above-described example embodiments.

[0063] Logic, commands, or instructions to implement various aspects of the methods described herein may be provided in a computing system, including any number of form factors of computing systems, such as desktop or laptop computers, mobile devices (such as tablets, netbooks, and smartphones), client and server-hosted machine instances, and the like. Another embodiment may include incorporating the techniques discussed herein into other forms, including other forms of programming logic, hardware configurations, or dedicated components or modules, including devices having corresponding means for performing the functions of such techniques. The corresponding algorithms for implementing the functions of such techniques may include sequences of some or all of the electronic operations described herein, or other aspects described in the accompanying drawings and detailed description below. Such systems and computer-readable media including instructions for implementing the methods described herein also constitute example embodiments.

[0064] In one embodiment, the functions described herein with respect to CPU 420 can be implemented in software. Software can consist of computer executable instructions stored on a computer readable medium or computer readable storage device (such as one or more non-transitory memories or other types of hardware-based local or network storage devices). In addition, such functions correspond to modules, which can be software, hardware, firmware, or any combination thereof. Multiple functions can be performed in one or more modules as needed, and the described embodiments are only examples. The software can be executed on a digital signal processor, an ASIC, a microprocessor, or other types of processors that operate on a computer system (such as a personal computer, a server, or other computer system) and turn such a computer system into a dedicated programmed machine.

[0065] As described herein, examples may include, or may operate on, a processor, a microcontroller, logic or multiple components, modules or mechanisms (hereinafter referred to as "modules"). A module is a tangible entity (e.g., hardware) that can perform a specified operation and may be configured or arranged in some manner. In an example, a circuit may be arranged as a module in a specified manner (e.g., internally or relative to an external entity such as other circuits). In an example, all or part of one or more hardware processors of one or more computer systems (e.g., independent, client or server computer systems) may be configured by firmware or software (e.g., instructions, application parts or applications) as a module that operates to perform a specified operation. In an example, the software may reside on a machine-readable medium. When executed by the underlying hardware of the module, the software causes the hardware to perform the specified operation.

[0066] Thus, the term "module" is understood to include tangible hardware and / or software entities, wherein an entity is physically constructed, specially configured (e.g., hardwired), or temporarily (e.g., temporarily) configured (e.g., programmed) to operate in a specified manner or perform part or all of any operations described herein. Considering examples where modules are temporarily configured, each module need not be instantiated at any one time. For example, where a module includes a general-purpose hardware processor configured using software, the general-purpose hardware processor can be configured as corresponding different modules at different times. The software can configure the hardware processor accordingly, for example, to constitute a particular module at one time instance, and to constitute a different module at a different time instance.

[0067] Those skilled in the art will appreciate that while the disclosure contained herein relates to an electronic eyeglass device having separate power supply circuits in physically separate portions of the electronic eyeglass device, it should be understood that this is only one of many possible applications and that other configurations are possible. Accordingly, all such applications are included within the scope of the appended claims.

Claims

1. A device comprising: a first circuit comprising a first battery, a first load, and a first resistor in a first current path to the first load; a second circuit including a second battery, a second load, and a second resistor in a second current path to the second load, the second circuit being physically separated from the first circuit; A battery balancing control loop, used to balance the charge of the first battery and the second battery, the battery balancing control loop comprising: a first current measuring circuit for measuring a first current passing through the first resistor, a second current measurement circuit that measures a second current through the second resistor, a differential amplifier that compares the first current and the second current to generate a regulation signal, and A current modulating device is used to modulate the first current in the first current path in response to the regulating signal to balance the charges of the first battery and the second battery.

2. The device according to claim 1, wherein: The current modulation device modulates the first current in the first current path by at least one of: (a) increasing the first resistance or reducing the battery voltage of the first battery; or (b) increasing the battery voltage of the first battery or reducing the first resistance.

3. The device of claim 1 , wherein the cell balancing control loop further comprises: a second differential amplifier that compares the first current and the second current to generate a second adjustment signal, and A second current modulation device is used to modulate the second current in the second current path in response to the second regulation signal to balance the charges of the first battery and the second battery.

4. The device according to claim 3, wherein: The second current modulating device modulates the second current in the second current path by at least one of: (a) increasing the second resistance or reducing the second battery voltage of the second battery; or (b) increasing the second battery voltage of the second battery or reducing the second resistance.

5. The apparatus of claim 1 , wherein the current modulation device comprises a transistor in the first current path of the first circuit, the transistor dynamically limiting the first current in the first current path by dynamically adjusting the first resistance in the first current path in response to the adjustment signal until the first current and the second current are substantially the same.

6. The device according to claim 1, wherein: The cell balancing control loop also includes a ramp circuit that examines the states of charge of the first cell and the second cell to determine a charge mismatch and discharges the cell with a higher charge until the states of charge of the first cell and the second cell are substantially equal.

7. The apparatus of claim 6, wherein the ramping circuit comprises a transistor in the first current path of the first battery that causes the first current to appear smaller when activated.

8. The device of claim 7, wherein the ramping circuit comprises a second transistor in the second current path of the second battery that, when activated, causes the second current to appear smaller.

9. The apparatus of claim 1 , wherein the cell balancing control loop further comprises an undervoltage lockout control loop, the undervoltage lockout controller loop comprising a first comparator, the first comparator comparing a first voltage applied to the first load with a reference voltage, and when the first voltage applied to the first load is lower than the reference voltage, the first comparator triggers the current modulation device to cancel its current modulation and add current to the first current path.

10. The apparatus of claim 9, wherein the undervoltage lockout control loop further comprises a second comparator that compares a second voltage applied to the second load with the reference voltage, and when the second voltage applied to the second load is lower than the reference voltage, the second comparator triggers the second current modulation device to cancel its current modulation and increase current to the second current path.

11. The apparatus of claim 1, wherein the current modulation device comprises a DC / DC converter, the DC / DC converter increasing the current in the first current path in response to the regulation signal to balance the first current and the second current.

12. A method of balancing battery discharge of physically separated circuits, each circuit comprising a battery, a load and a resistance in a current path to the load, the method comprising: measuring the current supplied from the battery of each circuit to the load; comparing the currents measured for each circuit to determine current mismatch; as well as The resistance or voltage is adjusted to reduce the current of the circuit having the higher current or to increase the current of the circuit having the lower current to balance the charge of the batteries of the circuits.

13. The method according to claim 12, wherein: Adjusting the resistance or voltage includes at least one of: (a) increasing the resistance or decreasing the battery voltage to reduce the current of a circuit with a higher current, thereby balancing the charge of the batteries of the circuit; or (b) increasing the battery voltage or decreasing the resistance to increase the current of a circuit with a lower current, thereby balancing the charge of the batteries of the circuit.

14. The method of claim 13, wherein the circuit comprises: a first circuit having a first battery, a first power transistor in a first current path to a first load, and a first resistor; and a second circuit having a second battery, a second power transistor in a second current path to a second load, and a second resistor, and wherein adjusting the resistance or voltage further comprises modulating the first power transistor in the first current path to the first load to dynamically adjust the first resistor to limit the current in the first current path when the measured current of the first current path is higher than the measured current of the second current path of the second circuit.

15. The method of claim 12, further comprising checking the charges of the batteries for any significant charge mismatch and prioritizing the circuits with the lighter load until the charges of the batteries are substantially equal.

16. The method according to claim 12, wherein: Adjusting the resistance or voltage also includes adjusting the resistance or voltage to regulate the charge of a battery of at least one of the circuits to remain above an undervoltage lockout point.

17. The method of claim 12, further comprising determining that a current of at least one of the circuits is above an upper current threshold, and disabling adjustment of a resistance or voltage of at least one of the circuits when the current of at least one of the circuits is above the upper current threshold.

18. The method of claim 12, further comprising determining that a current of at least one of the circuits is below a lower current threshold, and shutting down at least one of the circuits when the current of at least one of the circuits is below the lower current threshold.

19. The method of claim 12, further comprising determining that one of the circuits is predicted to have a dominant load, and disabling adjustment of a resistance or voltage of the one of the circuits when determining that the one of the circuits is predicted to have a dominant load.

20. An electronic eyewear device, comprising: frame; a left temple or arm on a left side of the frame; a right temple or arm on the right side of the frame; a first circuit in the left temple or arm, comprising a first battery, a first load, and a first resistor in a first current path to the first load; a second circuit in the right arm or temple, comprising a second battery, a second load, and a second resistor in a second current path to the second load, the second circuit being physically separated from the first circuit by the frame; A battery balancing control loop, which is used to balance the charge of the first battery and the second battery, the battery balancing control loop comprising: a first current measuring circuit for measuring a first current passing through the first resistor, a second current measurement circuit that measures a second current through the second resistor, a differential amplifier that compares the first current and the second current to generate a regulation signal, and A current modulation device is used to modulate the first current in the first current path in response to the adjustment signal to balance the charges of the first battery and the second battery.

Images