Burst charging for electrochemical devices

Abstract

Aspects of the charging system may involve altering the duty cycle of the shaped charging signal over a period of time to alter the average current supplied to the electrochemical device while maintaining the maximum current of the charging signal. For example, the average current of the charging signal used to charge a battery may be adjusted by changing the duty cycle or peak current of the shaped charging signal, and may, in some examples, be based on the state of charge, temperature, and / or impedance of the battery. In some examples, control of the average or total current of the charging signal is constrained by the maximum current that the system may supply, such that altering the duty cycle of the charging signal provides control of the average current of the charging signal without the need to supply an additional current source.

Description

[0001] Cross - Reference to Related Applications

[0002] This Patent Cooperation Treaty (PCT) application is related to and claims priority from U.S. Patent Application No. 63 / 406,691, filed on September 14, 2022, entitled "Burst Charge", the entire content of which is incorporated herein by reference for all purposes. Technical Field

[0003] Embodiments of the present invention generally relate to systems and methods for charging a battery, and more particularly, to systems and methods for controlling the sequencing of shaped charging signals for a battery. Background Art

[0004] Numerous different types of electric devices, such as power tools, mobile computing and communication devices, portable electronic devices, and all kinds of electric vehicles including scooters and bicycles, use rechargeable batteries as a source of operating power. Rechargeable batteries are limited by a finite battery capacity and must be recharged after depletion. Recharging a battery can be inconvenient because the power supply device must typically be stationary during the time required to recharge the battery. Depending on the battery size, recharging can take several hours. In addition, battery charging is usually accompanied by a degradation in battery performance. Therefore, a great deal of work has been devoted to developing battery charging technologies to shorten the time required to recharge a battery, improve battery performance, and reduce the degradation that a battery experiences due to charging, among other things.

[0005] It is in view of these observations, among other factors, that the various aspects of the present disclosure have been conceived and developed. Summary of the Invention

[0006] One aspect of the present disclosure relates to a method of charging a battery. The method may include the operations of: generating a series of charging signals, each charging signal being at a period T and each charging signal including a shaped leading edge and a body portion that deliver charging energy to the battery; and varying a duty cycle of the charging signals to vary an average charging current delivered by a combination of the shaped leading edge and the body portion.

[0007] Another aspect of the present disclosure relates to a method for charging an electrochemical device. The method may include the operations of: generating a charging signal that includes a shaped leading edge and a body portion that deliver charging energy to the battery, the charging signal having a first duty cycle and corresponding to a first average current within a signal period T; and after a first time period, changing the first duty cycle of the charging signal to a second duty cycle within the signal period T, the second duty cycle corresponding to a second average current of the charging signal, the second average current being different from the first average current within the signal period T. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] From the following description of the embodiments of those concepts of the present invention, various objectives, features, and advantages of the present disclosure set forth herein will be apparent, as shown in the accompanying drawings. It should be noted that the drawings are not necessarily drawn to scale and may represent various features of the embodiments, with the emphasis on showing the principles and other aspects of the concepts of the present invention. Also, in the drawings, the same reference numerals throughout different views may refer to the same or similar parts. The embodiments and the diagrams disclosed herein are to be regarded as illustrative rather than restrictive.

[0009] Figure 1 A schematic diagram of an example charging signal generator arrangement for defining and generating a charging signal for a battery.

[0010] Figures 2 to 4 A diagram of a charging signal for charging a battery with different duty cycles.

[0011] Figure 5 A signal diagram showing charging a battery with a constant average current of a charging signal.

[0012] Figure 6 A signal diagram showing burst charging a battery using different duty cycles of a charging signal.

[0013] Figure 7 A flowchart of a first method for managing the average current by changing the duty cycle of a tuned charging signal.

[0014] Figure 8 A flowchart of a second method for managing the average current by changing the duty cycle of a tuned / shaped charging signal.

[0015] Figure 9 A flowchart of a third method for managing the average current by changing the duty cycle of a tuned / shaped charging signal.

[0016] Figure 10 A signal diagram showing burst charging a battery using a controlled current and a controlled voltage of a charging signal.

[0017] Figure 11 A flowchart of a method for generating the shape of the charging portion of a signal, the method involving obtaining an impedance spectrum of a battery.

[0018] Figure 12 A diagram showing an example of a computing system that can be used to implement the embodiments of the present disclosure. DETAILED DESCRIPTION

[0019] Systems, methods, and apparatus for charging a battery or battery system are disclosed herein. Additionally, aspects of the charging system can involve changing the duty cycle of a shaped charging signal over a time period to change the average current supplied to an electrochemical device while maintaining the maximum current of the charging signal. For example, the average current of a charging signal for charging a battery can be adjusted by changing the duty cycle or peak current of the shaped charging signal, and can be based on the state of charge, temperature, and / or impedance of the battery in some examples. In some examples, control of the average or total current of the charging signal is constrained by the maximum current that the system can supply, such that changing the duty cycle of the charging signal provides control of the average current of the charging signal without the need to supply an additional current source. In some specific examples, the average current of the charging signal can be controlled to "burst charge" a battery by supplying a relatively high average initial current in the charging signal (or after an initial period) and then decreasing the average current within the charging cycle. Changing the duty cycle can include increasing the duty cycle to increase the average current of the charging signal, or decreasing the duty cycle to decrease the average current. As mentioned, the duty cycle can be changed in response to any characteristic of the battery or charging circuit. In some embodiments, the average current of the charging signal can be adjusted by changing the period of the charging signal. Additionally, the duration of the burst charge can depend on the type of battery or battery system being charged, as different cell chemistries can react to burst charging in different ways.

[0020] In one example, the various embodiments discussed herein charge a battery by generating a charging signal that is controllably shaped by a charging signal shaping circuit. Conventional charging techniques, such as constant current constant voltage (CCCV), do not involve charging signal shaping and can, in addition to being inefficient when charging a battery, also include frequencies or harmonics that can degrade battery performance over time. Accordingly, aspects of the present disclosure can include a shaped charging signal corresponding to harmonics (or a harmonic) associated with the efficient transfer of energy to the battery. In some examples, the charging signal shaping circuit can include a controller that generates control signals to components of the charging signal shaping circuit to shape or otherwise change the charging signal. In some embodiments, the controller can include a model of one or more components of the charging signal shaping circuit. The model can be used to validate and / or adjust the control for generating the signal based on an expected or established charging signal for charging the battery.

[0021] The term "battery" in this technology and in this document can be used in various ways and can refer to individual battery cells having an anode and a cathode separated by a solid or liquid electrolyte, as well as a series of such cells connected in various arrangements. A battery or battery cell is a form of electrochemical device. A battery typically includes repeating units of a source of opposite charges and electrode layers separated by an ion-conductive barrier, which is often a liquid or polymer film filled with an electrolyte. These layers are made thin so that multiple units can occupy the volume of the battery, thereby increasing the available power of the battery per stack of units. Although many of the examples discussed herein apply to batteries, it should be understood that the described systems and methods can be applied to many different types of batteries, ranging from individual cells to batteries involving different possible cell interconnections (e.g., cells coupled in parallel, in series, and in parallel and series combinations). For example, the systems and methods discussed herein can be applied to batteries that include many cells arranged to provide a defined set voltage, output current, and / or capacity. Additionally, the embodiments discussed herein can be applied to different types of electrochemical devices, such as various different types of lithium batteries, including but not limited to lithium metal and lithium-ion batteries, lead-acid batteries, various types of nickel batteries, and solid-state batteries of various possible chemistries, to name a few. The various embodiments discussed herein can also be applied to different structural battery arrangements, such as button or "coin" type batteries, cylindrical battery cells, pouch battery cells, and prismatic battery cells.

[0022] Figure 1 Shows a battery charging circuit topology according to an embodiment of the present disclosure. In Figure 1 it, the system is shown in a configuration that supplies current (charges) to a battery. The circuit can also be operated to power a load, charge only the battery, or power the load and charge the battery. As shown, the system includes an exemplary charging signal generator arrangement 100 for defining and generating a charging signal for battery 104. Generator 100 includes a processing unit or more generally a control unit, which can include a controller 106, such as a microcontroller, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a microprocessor, a combination thereof, or other processing arrangement, which can communicate with a signal generator 108 that generates control for generating a charging signal from a charging signal shaping circuit 110. In some examples, controller 106 can communicate with a model that can be part of generator 108 to generate control instructions for charging signal shaping circuit 110. The control unit including the controller and the model (if present) can be an integrated unit.

[0023] The system may also receive feedback 111 that includes battery measurements from battery measurement unit 116, such as current, voltage, and / or temperature at the battery terminals or more generally at the battery. Such battery measurements can be used to obtain impedance, state of charge, or other possible battery parameters or characteristics. Additionally, the system may include or be operatively coupled to a power source 118, which can be a voltage source or a current source. In one embodiment, power source 118 is a direct current (DC) current or voltage source, although an alternating current (AC) source is also contemplated. In various alternatives, power source 118 can include a DC source that provides a unidirectional current, an AC source that provides a bidirectional current, or a power source that provides a ripple current (e.g., an AC signal with a DC bias to make the current unidirectional). Generally, power source 118 supplies charging energy, such as current, that can be shaped or otherwise conditioned by controller 106 and circuitry 110 to produce a controllably shaped charging signal that charges battery 104 and / or is otherwise applied to the battery. In one example, controller 106 can provide one or more inputs to signal generator 108, which controls switches to generate pulses to circuitry 110, which may also be referred to as a filter, that produces a shaped signal at the battery.

[0024] In some examples, signal shaping circuitry 110 can modify the energy from power source 118 to generate a signal that is shaped based on conditions at battery 104, such as a signal that at least partially corresponds to one or more harmonics based on impedance when a signal including harmonics or harmonic attributes is applied to battery 104. In Figure 1 examples and other aspects, circuitry 100 can include a battery measurement unit 116 connected to battery 104 to measure cell voltage and / or charging current as well as other battery attributes such as temperature, and to measure, calculate, or otherwise obtain the impedance and other characteristics of battery 104 in the presence of a charging signal. In one example, battery characteristics can be measured based on signals going in and out of the battery. In another example, battery cell characteristics can be measured as part of a routine that applies signals with different frequency attributes to generate a range of battery cell characteristic values associated with the different frequency attributes in order to characterize the battery, which can be done before charging or otherwise managing energy going in and out of the battery, during charging, periodically during charging, and can be used in combination with lookup techniques and other techniques. Battery characteristics can vary based on many physical or chemical characteristics of the battery, including the state of charge and / or temperature of the battery. Thus, battery measurement circuitry 116 can be controlled by controller 106 to determine various battery characteristic values of battery 104 during recharging of the battery, and to provide the measured battery characteristic values to controller 106 or other parts of generator 100.

[0025] During charging, the controller 106 may generate an expected charging signal for effective charging of the battery 104. For example, the controller 106 may generate or select a charging signal having an attribute corresponding to a harmonic associated with an optimal impedance (which may be an impedance range) for energy transfer, which may be associated with the minimum impedance value of the battery 104, using the determined impedance of the battery 104 or a signal definition characterized based on the impedance effect of the understanding signal on the battery. Thus, the controller 106 may execute a charging signal algorithm that outputs a charging signal shape based on the measured, characterized, and / or estimated charging conditions of the battery 104. Generally, the signal generator controls switches to generate a pulse sequence at node 136, which is converted by the circuit 110 into a charging signal shape. The control signal may shape or otherwise define the signal to the battery to approximate the shaped charging signal determined, selected, or otherwise obtained by the controller 106, among other functions. The charging signal shaping circuit 110 may further filter out any unwanted frequency attributes from the signal. In some examples, the shaped charging signal may be any arbitrarily shaped signal such that the signal is not a constant DC signal and is inconsistent with conventional repetitive charging signals (such as repetitive square wave or triangular wave charging signals).

[0026] According to one embodiment, Figure 1 the circuit of includes switching elements 112, 114, which may be considered part of the circuit 110, to generate an initial sequence of controlled pulses at node 136, which is then converted by the filter 110 into a shaped signal to produce a signal to the battery. The switching elements may also be used to generate a discharge signal from the battery by pulses similarly generated at node 136 in the absence of a charging current on the rail 120.

[0027] The circuit 100 may include a first switching element (e.g., transistor 112) and a second switching element (e.g., transistor 114), where the first switching element is connected to a power rail and thus to a power supply 118. In some examples, power may also be delivered from a capacitor 122. The capacitor 122 (which may also be referred to as a tank capacitor) is a local energy storage device closer to the battery 104 relative to the power supply to reduce the series resistance in the provided energy for charging the battery. In some embodiments, the charging current may be from the power supply 118, the tank capacitor 122, or a combination of the power supply and the tank capacitor. Since the series resistance between the load (battery) 104 and the power supply 118 is higher than the series resistance between the load and the capacitor 122, initially most of the charging current comes from the capacitor. However, once the capacitor 122 is depleted, any additional current may come from the power supply 118. The presence of the tank capacitor 122 may also improve voltage stability, which is particularly applicable when shaping the charging signal predictably, among other advantages. As will be apparent from the various charging waveforms discussed in more detail below, since the charging energy delivered to the battery 104 can be changed by controlling the duty cycle of the charging signal, which may include a rest period between active charging signals, the tank capacitor 122 can be recharged during these rest periods.

[0028] The first transistor 112 may receive an input signal such as a pulse width modulation (PWM) control signal 130 to operate the first transistor 112 as a switching device or component. Generally, the first transistor 112 may be any type of transistor, such as a FET, or more specifically, a MOSFET, a GaN FET, a silicon carbide-based FET, or any type of controllable switching element suitable for operating at the power level of any given use case or embodiment. For example, the first transistor 112 may be a FET where the drain node is connected to a first inductor 140, the source is connected to a rail, and the gate receives the control signal 130 from a signal generator 110. In various embodiments, the circuit 110 also includes an inductor 140, but may also have various other possible inductive elements.

[0029] To supply current (charge), the circuit controller 106 may provide a control signal 130 to control the operation of the first transistor 112 as a switch that, when closed, connects the first inductor 140 to the rail 120 such that current from the power source (and / or sourced from the capacitor 122) flows through the first inductor 140 and, if present, the second inductor 142, to the battery. The second transistor 114 may receive a second input signal 132 and may also be connected to the drain of the first transistor 112 at node 136. In a charging scenario, and in some examples, the second input signal 132 may be a PWM signal that is opposite to the first control signal 130 to the first transistor 112 such that the switches are coordinated by turning one transistor on and the other off.

[0030] One or more inductor values, one or more capacitor values, the time and frequency to actuate the transistors, and other factors may be adjusted to generate a waveform, and in particular a waveform with a controlled shape, that is commensurate with some understanding of the impedance effects on certain harmonics or more generally the frequencies at the battery. Additionally, the shaped signal may be operated on or otherwise controlled based on the duty cycle. During the control of the charging circuit, a combination of factors that define the charging signal may be controlled to vary the average current of the charging signal. For example, the average current of the charging signal used to charge the battery 104 may be adjusted by changing the duty cycle or peak current of the shaped charging signal and may, in some examples, be based on the charge state, temperature, and / or impedance of the battery. In some examples, the control of the average or total current of the charging signal is constrained by the maximum current that the system can supply, perhaps due to cost constraints, infrastructure (socket power limitations), or other factors.

[0031] Reference Figures 2 to 4 to the example signals illustrated in, when supplying current (and in response to the control signal provided to transistor 112 and, in some cases, transistor 114) the signal at node 136 may be a series of pulses between 0 volts and approximately the rail voltage at rail 120. The pulses at node 136 may have different duty cycles and may be generated at different frequencies. The duty cycle of the pulses that produce the shaped signal at node 136 should not be confused with the duty cycle of the charging signal itself. Generally, pulses are generated to produce a signal that is the same or nearly the same as the expected current signal into (or out of) the battery. Thus, for example, a signal such as any one of those signals in Figures 2 to 4 will be at node 138 based on the combination of pulses present at node 136 that are then shaped by the filter arrangement 110 into the signal at 138. Depending on the signal, dozens to thousands (or more) of pulses may be generated to form the desired charging signal.

[0032] Figure 2An example charging signal 202 with a 100% duty cycle is shown during period t1 204. The charging signal 202 is considered to have a 100% duty cycle because the charging signal is active throughout the period t1 204. In Figures 2 to 4 the example illustrated, the period t1 may correspond to the inflection point of the leading-edge sine curve of the first pulse of the charging signal to the corresponding inflection point of the leading edge of the next pulse of the charging signal. This point can be selected as the start of the period t1 because the area under the curve of the charging signal before the inflection point can be similar to the area under the curve after the inflection point until the main part of the signal. Thus, a more accurate duty cycle estimate of the charging signal can be determined by setting the start of the period t1 to the inflection point of the leading-edge sine curve. In other examples, the period can be measured from any point on the charging signal. In various examples, the period t1 can range from a few milliseconds to several seconds. In this case, the leading edge 206 of the signal 202 is shaped to define a portion of a sine curve at a frequency or an approximate frequency thereof. In some examples, the sine curve can be associated with the impedance of the battery 104. By comparison, Figure 3 An example charging signal 302 with a 50% duty cycle is shown during the same period t1 204. In this example, the leading edge 306 of the signal 302 is shaped, similar to Figure 2 , although the main body 308 of the signal is relatively short at a relatively constant current for a time period slightly less than t2, where the trailing edge 310 (after the period t2 304) returns the charging signal of the constant current from the main body to some smaller value, which can be 0 amperes during the rest period at approximately half of the period t1 204. It should be understood that the maximum current during the rest period is less than the maximum current during the main body portion 308. The signal can then be repeated at the same or a different duty cycle determined by the controller 106. Figure 4 An example charging signal 402 with a 25% duty cycle is shown during the same period t1 204. In this example, the leading edge 406 of the signal 402 is shaped, similar to Figure 2 and 3 the signals in, and with a smaller duty cycle and a relatively long rest period after the trailing edge, the main body 408 of the signal is shorter (within the period t3 404).

[0033] Figures 2 to 4 The signal curves shown in illustrate how reducing the duration for which the charging signal remains at the maximum current (I max ) in different duty cycles can change the average current (I avg) Note that the maximum current can vary with many aspects of the circuit and / or the charging signal, such as the power supply, the tank capacitor (e.g., capacitor 122), the duty cycle, and the signal period. Thus, if the tank capacitor and the power supply are held fixed, a signal with a short period and a low duty cycle can produce a higher I than a system with the same duty cycle and a longer period. max current. Thus, for Figures 2 to 4 the set of example curves shown in max is held fixed while the duty cycle varies to simplify the concept of how changing the duty cycle produces a lower average current.

[0034] Figure 5 A graph showing a first example of controlling the average current of a charging signal until the average / target voltage of the battery is reached at a fixed period, duty cycle, and I max is shown. The state of charge of the battery being charged is also shown in the graph. Specifically, graph 500 shows curves for the average current 502 of the charging signal, the voltage 504 of the charging signal, and the state of charge 506 of the battery. In this example, the average current 502 of the charging signal can be maintained at a constant value as the voltage 504 and the state of charge 506 of the battery increase until the battery is fully charged. After the battery has been charged for a certain amount of time (represented by arrow 508), the system can change some aspects of the charging signal (e.g., duty cycle, period, and / or I max ) to reduce the average current and thus maintain the target voltage. Point 508 can be based on any characteristic of the battery, such as the state of charge. Point 508 can also be based on the voltage 504 of the charging signal such that when the voltage reaches the target value. To maintain the voltage at the target value, the above characteristics can be adjusted by the controller 106 or other components of the charging circuit. For example, the system can reduce the average or maximum current by changing the duty cycle or period of the charging signal rather than simply reducing the current of the charging signal. This allows the system to continue injecting charging current using a charging signal and rest periods that are advantageously harmonically shaped. This method also allows the current to be reduced at a certain point (e.g., point 508) to continue optimizing other aspects of the battery (e.g., life, heat, etc.) while charging at a rate that is relatively higher than what may be possible with conventional DC charging without damaging the battery.

[0035] Figure 6 Graph 600 showing a second example of a burst charging method of changing the duty cycle to affect the fast charging of a battery. In this example, the duty cycle of the charging signal can be controlled starting from 100% and stepped down at different times indicated by arrows 608 to 614 while maintaining I maxAnd the period is constant. In this example, the average current into the battery is reduced by stepping down the duty cycle sequentially at the indicated times. In general, the duty cycle step down can be initiated based on any characteristic of the battery and / or the charging circuit (e.g., the charge state level 606, the voltage level 604, and / or the temperature of the battery).

[0036] Figure 7 FIG. is a flow chart depicting a method for managing the average current of a tuned charging signal by duty cycle change. The operations of method 700 can be performed by Figure 1 any part of the charging circuit, and in some particular embodiments, by the controller 106. As explained in more detail below, the controller 106 can utilize Figure 1 components or measurements of the circuit to assist in adjusting the duty cycle of the charging signal to effect the charging of the battery.

[0037] In this example, a measurement of a characteristic of the battery 104 can be made at step 702, for example, via sensor feedback 116. Such measurements can include the voltage across the battery, the current into the battery, the temperature of the battery, etc. At step 704, it is determined whether the battery voltage is greater than a minimum voltage value, such as zero. If not, the battery 104 may not be present or otherwise connected to the charging circuit, and a charging signal may not be generated at step 706. At step 708, a low average current can be applied to the battery charging signal to charge the battery 104. In some examples, the low average current can be based on the battery being charged. For example, the low average current generated at step 708 can be about 5 amperes for an M35A cell or 8 amperes for a 30T cell. Generally, the low average current can be any amount and, in some examples, is based on the type of battery being charged. In one example, the charging signal can be controlled to have a low duty cycle that corresponds to the desired average current for charging the battery during this first time period. The terminal voltage of the battery 104 can continue to be monitored at step 710, and at a first voltage value (e.g., 3.0 volts for an example lithium-ion cell), the battery cell can be charged with a relatively high average current at step 712. This higher average current of the charging signal can be controlled by increasing the duty cycle of the charging signal. Between the first voltage and a second voltage (e.g., 3.7 volts in the example cell), the battery 104 is charged with a relatively high average current (e.g., a relatively high duty cycle). At step 714, it can be determined whether the battery 104 is charged to a voltage limit (e.g., 4.2 volts), and if not, the system switches back to a lower average current at step 716. Once the voltage limit is reached, the average voltage of the charging signal can be maintained because the average current is allowed to decay at step 718 until the charging cycle ends at step 720. In one example, when the trigger threshold voltage limit is reached, the system maintains the battery at the voltage limit by actively reducing the current (e.g., actively reducing the average current) while evaluating the measured voltage relative to the threshold voltage limit. At the end of charging, if the current is maintained at its value, the terminal voltage will begin to rise and exceed the voltage limit. Thus, to maintain the voltage at the voltage limit, the battery voltage can be measured, and the average current can be reduced to offset the voltage that would otherwise be a rising voltage if the current were not reduced. This can be done based on time or otherwise until the charging condition ends, such as a minimum lower average current, when 100% SOC is reached. The end of charging 720 can occur based on any characteristic of the battery (such as 100% SOC) or until the average current decays to a certain threshold (such as 0.5 amperes or some other value, possibly based on the type of battery cell being charged). The switching from high average current to low average current can provide significant advantages over traditional charging techniques.More precisely, in many cases, the impedance at battery 104 can be higher at lower voltages, and thus, a lower average current can be used at different times during the charging process (e.g., during the initial part of the charging cycle when the battery voltage is at its lowest voltage). This would contrast with many techniques that typically dictate using a higher current at lower voltages.

[0038] Figure 8 To depict a flowchart of a second method for managing the average current of a tuned charging signal by duty cycle change (and / or period, similar to Figure 7 the method). Similar to above, the operations of method 800 can be performed by Figure 1 any part of the charging circuit, and in some particular embodiments, by controller 106. As explained in more detail below, controller 106 can utilize Figure 1 components or measurements of the circuit to assist in adjusting the duty cycle of the charging signal to implement charging of the battery.

[0039] In this example, a measurement of the characteristics of battery 104 can be made at step 802, and as described above, it can be determined at step 804 whether the battery voltage is greater than zero. If not, then battery 104 may not be present or otherwise connected to the charging circuit, and a charging signal may not be generated at step 806. At step 808, the state of charge (SOC) of the battery and the estimated error in the determined SOC can be determined. In one example, the SOC can be estimated by a coulomb counting technique, where the discharge current of the battery is measured and integrated over time to estimate the SOC. In another example, an SOC estimator utilizing a Kalman filter can be used in the circuit. However, generally speaking, the charging systems discussed herein can utilize other techniques for estimating the SOC of the battery, such as techniques that utilize the voltage of the battery and / or the state of health of the battery. The estimated error in the SOC can be determined by similar techniques, such as Kalman filter techniques, which compare the determined SOC with a previous estimated SOC value. In another example, the determined SOC can be compared with the estimated SOC by another technique, such as an open circuit voltage technique or by using a look-up table to find an expected SOC value. Generally speaking, any known technique can be used to estimate the error in the determined SOC of the battery.

[0040] The method can first use something similar to Figure 7The battery voltage threshold of the method is used to determine the average current of the charging signal. Thus, at step 810, it can be determined that the battery voltage is between 0 volts and a certain threshold (e.g., 3.0 volts, but any threshold can be used). During this charging cycle, a low average current can be applied to the battery charging signal to charge the battery 104. In one example, the charging signal can be controlled to have a low duty cycle, and the low duty cycle corresponds to the desired average current for charging the battery during this first time period. In another example, the period of the charging signal can be controlled to provide a relatively low average current charging signal.

[0041] At step 814, the system can evaluate the charging state of the battery 104, and at step 816, trigger a higher average current until a threshold charging state (e.g., reaching 50%). The method can also evaluate the error in the charging state evaluation and act when the error is below a certain value (e.g., 2%), which can also affect the SOC threshold. Above the threshold SOC and until the battery is charged, the system can return to a lower average current charging by reducing the duty cycle or adjusting the period of the charging signal. Specifically, at step 818, the system can determine that the SOC of the battery 104 is between 50% and 100%, and at step 820, generate a low average current charging signal. Once the SOC is estimated to be 100%, or more likely a value less than 100% SOC (e.g., between 95% and 99%), the average voltage of the charging signal can be maintained because at step 822, the average current is allowed to decay until the charging cycle ends at step 824. In one example, when triggering the SOC, the system evaluates the voltage with respect to the threshold voltage while actively reducing the current. The reduction of the current can be achieved by reducing the average current and various techniques discussed in Figures 2 to 4 this and other aspects herein. At the end of charging, if the current is maintained at its value, the terminal voltage will start to rise. Thus, to maintain the voltage at the threshold voltage, the battery voltage can be measured, and the average current can be reduced to offset the voltage that would otherwise be a rising voltage without reducing the current. This operation can be performed until the charging condition ends at 100% SOC, such as a certain minimum lower average current, or otherwise.

[0042] It should be recognized that the threshold of the battery voltage, the charging state (with or without error), and other factors (e.g., battery temperature) can be involved in setting the duty cycle and determining when to change the duty cycle. In some examples, the system can start with a set duty cycle that reflects the expected average current at any initial battery voltage, charging state, and / or temperature or otherwise. Adjustments can then be made based on any of the factors discussed herein to adjust the average current of the charging signal generated by the charging circuit.

[0043] Figure 9A flowchart depicting a third method for managing the average current of a tuned charging signal by duty cycle change. In this method, the average current of the charging signal can start at a high average current and step down during the charging cycle through duty cycle and / or period control, such as Figure 6 depicted in graph 600 of. The step down of the average current can be based on any characteristic of the charging signal or components of the charging circuit. For example, the step down of the average current can be based on characteristics of the battery 104, such as voltage and / or charge state. Thus, although the step down of the average current based on the voltage of the battery is described, any other characteristic of the battery 104 can be used as a threshold for adjusting the average current. Additionally, the adjustment of the average current can include adjusting the duty cycle of the charging signal, the period of the charging signal, or any other aspect of the charging signal or circuit discussed herein.

[0044] In Figure 9 an example method, a measurement of a characteristic of the battery 104, such as the voltage across the battery, the current into the battery, the temperature of the battery, etc., can be made at step 902. At step 904, it is determined whether the battery voltage is greater than zero, and if not, the battery 104 may not be present or otherwise connected to the charging circuit, and a charging signal may not be generated at step 906. If the battery 104 is present, then at step 908, a charging signal having a high average current can be applied to the battery charging signal that charges the battery 104. In some examples, this highest average current can be applied after an initial period in which the voltage of the battery increases to avoid low-voltage, high-impedance charging of the battery. The average current applied to the battery 104 during this period can be the highest average current of the charging signal during this charging cycle. The terminal voltage of the battery 104 can continue to be monitored at step 910, and when the battery voltage reaches a first voltage threshold (e.g., 3.0 volts for an example lithium-ion cell), the average current of the charging signal can be reduced to a second high average current at step 912. In one implementation, this second higher average current of the charging signal can be controlled by adjusting the duty cycle of the charging signal.

[0045] Between a first voltage threshold and a second voltage threshold (e.g., 3.7 volts for an example cell), the battery 104 is charged at the second highest average current. Similarly, at step 914, the terminal voltage of the battery 104 can continue to be monitored, and when the battery voltage reaches the second voltage threshold (e.g., 3.7), the average current of the charging signal can be reduced again to the third highest average current at step 916. This step-down of the average current of the charging signal can continue through any number of thresholds of the characteristics of the battery and / or the charging circuit. Finally, at step 918, it can be determined whether the battery 104 is above a fourth voltage threshold (e.g., 4.2 volts or 4.5 volts) but not fully charged. If so, at step 920, the charging signal can be adjusted to generate a low average current relative to the previous charging signal. Once the battery is charged to the voltage limit (e.g., 4.2 volts), the average voltage of the charging signal can be maintained because the average current is allowed to decay at step 922 until the end of the charging cycle at step 924. The end of charging can be managed as discussed above with respect to the methods of Figure 7 and Figure 8 . Thus, for example, the average charging current can be actively reduced to maintain the voltage limit, and the average charging current can be continuously reduced until the end-of-charge condition is reached. It should be noted that the change in the average current can occur within any of the steps described above. For example, the low average current of step 920 may not be the average current maintained over a time period, but may be the average current in response to a constant voltage of the charging signal, such as illustrated between time 612 and time 614 in Figure 6 . The period of charging signal control using a constant voltage instead of a constant average current is discussed in more detail below.

[0046] As mentioned, the thresholds for adjusting the average current can be based on the battery cell type. For example, an M35A type battery cell can have an initial average current of 8.7 amperes (with a peak current of 10.2 amperes) until 40% SOC is reached. The average current can then step down to 7.4 amperes (with a peak current of 8.7 amperes) until 70% SOC of the battery is reached, at which point the average current can be adjusted down to 5.4 amperes (a peak current of 6.3 amperes) until the end of the charging cycle. The average current of the charging signal can be adjusted to such values by changing the duty cycle and / or period of the signal. In another example, a 30T type battery cell can have an initial average current of 12.2 amperes (with a peak current of 16.5 amperes) until the battery voltage reaches 3.9 volts. The average current can then step down to 8.0 amperes (with a peak current of 10.8 amperes) until the end of the charging cycle. The battery types and thresholds provided herein are only examples of how the various thresholds can be adjusted or changed to charge different types of battery cells.

[0047] Figure 10Graph 1000 of another example of the variable average current of a charging signal that charges battery 104 over time, where the average current 1002 and voltage 1004 of the charging signal are shown in the graph. As described above, the average current 1002 can be adjusted during charging by varying the duty cycle and / or period of the charging signal. Similar to the burst charging technique discussed above regarding Figure 6 At or near 100% at the start of the charging cycle, the duty cycle of the charging signal can be controlled to provide a maximum current to battery 104 during the initial charging portion. Since the average current of the charging signal is being controlled, this period is considered the controlled current period of the charging signal. However, at time 1006, the voltage of the charging signal can be controlled (possibly by controller 106) to be constant during a second time period. During this second time period, the average current 1002 of the charging signal can be controllably decreased to maintain the voltage at a constant voltage.

[0048] At time 1008, the duty cycle of the charging signal can be controlled to cause a rest period of a smaller average current in the charging signal. A "drop - out" period can be provided in the charging current to allow the temperature of the battery to decrease so that battery 104 does not overheat. Since high temperatures can damage the battery and applying the charging signal to the battery can increase the battery's temperature, removing the charging signal from the battery during a cooling cycle can extend the life of battery 104. The duration of the cooling cycle can depend on many characteristics of battery 104, including the stored information and / or measured characteristics of the battery. Additionally, the cooling cycle can be triggered based on any aspect of the charging signal and / or components of the circuit, such as the charging time, the measured or derived battery temperature, the voltage of the battery, the impedance, etc.

[0049] After the cooling period, the charging signal can be adjusted again to provide a controlled average current, e.g., at cycle 1010. The controlled average current during this cycle can be less than the initial average current 1014 of the charging signal, such that the average current is stepped down, as described above. This mode of controlling the average current by duty cycle control with controlled voltage periods and cooling periods can be repeated any number of times and can be triggered or based on any characteristic of the charging signal and / or the charging circuit. At some point, e.g., time 1012, the voltage of the charging signal can be controlled at a level while controllably reducing the average current 1002 to a level at which the battery is considered fully charged. The controlled voltage 1004 period can continue until the battery reaches full charge or the end of the charging cycle occurs. In this way, through duty cycle control of the charging sequence, a combination of a controlled constant voltage and a controlled constant average current can be implemented in the charging signal to charge the battery 104. Additionally, one or more cooling periods can be implemented to allow maintaining, stopping, or slowly increasing and / or decreasing the temperature of the battery during charging. For example, if the rate of temperature rise would cause it to exceed a certain threshold during the charging sequence, one or more off periods can be implemented to fully charge the battery without exceeding the temperature threshold. The charging techniques described herein can improve the efficiency and speed of battery charging while reducing damage to the battery caused by high current charging.

[0050] As noted herein, the charging signal can include a shaped leading edge, a body portion, and a rest period. The charging techniques and charging signal described are not conventional constant current constant voltage type charging, in which, in essence, a prescribed constant charging current is applied until the battery voltage begins to rise, at which point the charging current is reduced. Instead, the charging signal is described in terms of the average current supplied to the battery 104 through a combination of the shaped leading edge signal and the overall duty cycle of the body portion and rest period (if present). The charging technique is also not pulse charging, as the charging signal defines a specifically shaped leading edge; in fact, square pulses with high frequency harmonic content are generally avoided for charging, at least due to the high impedance of the uncontrolled high frequency harmonic content of the square pulse (especially when the pulse first starts).

[0051] Now turning to Figure 11 , a method of generating a shape for the charging portion of a signal involves obtaining an impedance spectrum of the battery and selecting a frequency with relatively low impedance from the impedance spectrum and using the frequency to define the shaped leading edge of the charging portion of the signal. In one example, the system uses or otherwise references the imaginary part impedance (reactance) value. The shaped leading edge and the overall signal can use Figure 1It can be generated by the circuit depicted in [description] etc. The harmonic content can be obtained in real time, or by characterizing the battery cell under various numbers of cycles and charging conditions (including temperature and state of charge), where the leading edge shape can also be tuned in real time or pre-programmed based on the characterization.

[0052] To obtain an impedance spectrum, in one possible example, the method involves applying a probing signal to the battery (operation 1102). The probing signal can include a harmonic spectrum, which can be used by the system to evaluate the impedance of the battery to various harmonics. The probing signal can be a charging signal or a dedicated signal. The probing signal can be interleaved during charging or run discretely at the start of charging or otherwise. In one example, the probing signal can be a square wave or a square pulse. In a particular example, the probing signal is a square wave centered at zero amperes. In one possible example, the probing signal is a square wave centered at zero amperes, having a +4V (positive) part and a -4V (negative) part. Here, the average current is 0A. The duty cycle is 50%. The frequency, duty cycle, current or voltage magnitude, or other attributes of the probing signal can vary depending on the cell type, device type, temperature, state of charge, and other possible parameters. These parameters can be determined based on the characterization of any given cell type. In a particular example, a square wave probe is applied to the battery for a single cycle of about 30 milliseconds. In other words, the probing signal can include a square pulse of a certain current and a negative square pulse of a certain current. The pulses can have the same duration, for example, 15 milliseconds each pulse, or can have different durations. The probing signal can be only a positive pulse (current to the battery) or only a negative pulse (discharge current from the battery). Each pulse can contain the same magnitude of current, or the pulses can be asymmetric. Although other probing signals are possible, square pulses or square waves have harmonic content over a wide frequency range and are effectively generated by a series of conventional charging hardware topologies, which can also be used to generate the heating signals and shaped charging signals discussed herein. Generally speaking, the purpose of the probing signal is very simple and discretely introduce a broad spectrum of harmonic content into the battery in order to evaluate the impedance of the battery to various harmonics. Therefore, whether it is a square wave, a square pulse, or other signals, the probing signal is intended to briefly introduce a harmonic spectrum into the battery. In the case of a square wave centered at zero amperes, there can also be equal magnitudes of current flowing in and out of the battery, with little or no net charge effect. In some arrangements, a series of different probes with different harmonic contents can be injected. Although uncontrolled and / or high-frequency harmonics may have harmful effects on the battery, for the purpose of obtaining the impedance spectrum, the system applies square pulses only for a very short duration, thus substantially avoiding such effects.

[0053] In the presence of a probe signal, the system measures the current and voltage at the battery terminals (operation 1104). The current and voltage signals are captured in the time domain. For each of the current and voltage measured in the presence of the probe signal, the system obtains a spectrum from which the system may further generate an impedance spectrum (operation 1106). In one example, the system generates a domain transform of the current and voltage signals to produce a voltage spectrum and a current spectrum. The domain transform may be a discrete wavelet transform using a Morlet wavelet. In some examples, the wavelet may also be regarded as a Gabor wavelet or a complex Morlet wavelet. In one possible implementation, the system may use fixed-point arithmetic to generate the impedance spectrum, which may allow the use of a relatively low-cost and simpler microcontroller or other computing platforms more typical of some charging environments where a large amount of computing power may not otherwise be necessary.

[0054] The system generates an impedance spectrum based on the spectra of the current and voltage signals (operation 1106). In one example, the impedance spectrum is generated by dividing the voltage spectrum by the current spectrum. More precisely, the complex voltage values at various frequencies are divided by the complex current values at the same frequencies to generate the impedance at various frequencies. This may generate a complex-valued impedance spectrum. In some examples, it may be sufficient to limit the generation of the impedance spectrum to a discrete frequency range (e.g., 200 HZ to 3 KHZ).

[0055] Regardless of the technology, the system generates an impedance spectrum that identifies the impedance of the battery at specific frequencies of the harmonics of the signal applied to the battery. Thus, in a simplified example, in a square pulse probe signal applied to the battery, there will be multiple harmonics. Through the techniques discussed herein, the system generates the discrete impedance of the battery to some or all of the discrete harmonics in the probe signal. The spectrum generally shows the resistance of the battery to a charging signal at a specific frequency. The battery may have more or less impedance (more generally, resistance) to different frequency harmonics of the probe signal.

[0056] Based on the impedance spectrum, the system may identify a specific harmonic for defining the leading edge of the charging portion of the signal (operation 1108). To determine the shape of the leading edge of the charging signal, the system determines an optimal frequency based on the impedance spectrum generated from the probe signal. In one particular example, the optimal frequency is the frequency associated with the lowest impedance (more precisely, the reactance in some embodiments) in the impedance spectrum. Thus, the system selects the frequency associated with the lowest impedance. It should be understood that there may be examples where the system may actually evaluate the admittance (e.g., the highest admittance or the imaginary part of the admittance, i.e., susceptance). Generally, a charging signal having a shape with a frequency associated with a lower impedance will transfer energy for charging more efficiently to the battery than a frequency associated with a higher impedance. Subsequently, the optimal frequency is set as the leading edge of the charging signal or the charging portion of the hybrid signal.

[0057] In addition to the shape of the leading edge of the charging portion, the system also determines the overall attributes, overall signal period, and other attributes of a signal that includes the length of the rest period relative to the charging time (including the shaped portion and the body portion). In one possible example, the period and rest period of the charging signal are preset and are based on battery characterization. The period of the charging signal includes the shaped leading edge and the body portion that follows the shaped leading edge. In various possible examples, the charging portion can range from hundreds of microseconds to tens of milliseconds. The entire period includes the charging portion and the rest period (or heating portion). The rest period (or heating portion) can range from hundreds of microseconds to tens of milliseconds. In other possible examples, the period can range from hundreds of microseconds to tens of milliseconds. The peak current at the peak of the shaped leading edge and the body portion of the charging portion of the cell can be about 20 A, but the peak current value depends on cell type, temperature, characteristics, and other factors and can thus be significantly different from the example peak current. An example of determining the charging current (including the peak current) is discussed below.

[0058] The method of determining the shape of the leading edge can be repeated throughout the heating or charging cycle. In one example, the probing signal and subsequent operations (1104 to 1110) are repeated at approximately every 1 / 2% to 1% change in SOC. In another example, the probing signal and subsequent operations are performed over time (e.g., every 5 seconds, every 30 seconds, or every 60 seconds). The frequency of the probing signal and subsequent operations can change over time. For example, as the cell heats up, the cell can change more rapidly and thus the probing rate, etc. can change. The probing rate can also change when the cell approaches full charge.

[0059] Reference Figure 12, a detailed description of an example computing system 1200 having one or more computing units capable of implementing the various systems and methods discussed herein is provided. Computing system 1200 may be part of a controller, may be operably communicable with the various embodiments discussed herein, may run various operations related to the methods discussed herein, may run offline to process various data for characterizing a battery, and may be part of the overall system discussed herein. Computing system 1200 may process the various signals discussed herein and / or may provide the various signals discussed herein. For example, battery measurement information may be provided to such a computing system 1200. Computing system 1200 may also be applicable to, for example, controllers, models, tuning / shaping circuits discussed with respect to the various figures, and may be used to implement the various methods described herein. It should be understood that the specific implementations of these devices may be different possible specific computing architectures, and not all of the computing architectures are specifically discussed herein, but they will be understood by those of ordinary skill in the art. It will be further understood that a computer system may be considered and / or include an ASIC, FPGA, microcontroller, or other computing arrangement. In such various possible embodiments, more or fewer components as discussed below may be included, with interconnections and other changes as will be understood by those of ordinary skill in the art.

[0060] Computer system 1200 may be a computing system that can execute a computer program product to execute a computer process. Data and program files may be input into computer system 1200, and the computer system reads the files and executes the programs therein. Figure 12 Some of the elements of computer system 1200 are shown, including one or more hardware processors 1202, one or more data storage devices 1204, one or more memory devices 1206, and / or one or more ports 1208 to 1212. Additionally, other elements that would be recognized by those of ordinary skill in the art may be included in computing system 1200, but are not explicitly depicted in Figure 12 or further discussed herein. The various elements of computer system 1200 may communicate with each other via one or more communication buses, point-to-point communication paths, or Figure 12 other communication components not explicitly depicted in. Similarly, in various embodiments, the various elements disclosed in the system may or may not be included in any given embodiment.

[0061] Processor 1202 may include, for example, a central processing unit (CPU), a microprocessor, a microcontroller, a digital signal processor (DSP), and / or one or more levels of internal cache. There may be one or more processors 1202 such that processor 1202 includes a single central processing unit or multiple processing units capable of executing instructions and performing operations in parallel with each other, which is commonly referred to as a parallel processing environment.

[0062] The techniques described in the present invention in all possible combinations can be implemented, at least in part, in software stored on data storage device 1204, stored on memory device 1206, and / or transmitted via one or more of ports 1208 to 1212, thereby transforming Figure 12 the computer system 1200 in

[0063] One or more data storage devices 1204 can include any non-volatile data storage device capable of storing data generated or employed within computing system 1200, such as computer-executable instructions for performing computer processes, which can include instructions for both application programs and an operating system (OS) that manages the various components of computing system 1200. The data storage device 1204 can include, but is not limited to, disk drives, optical disc drives, solid state drives (SSDs), flash drives, etc. The data storage device 1204 can include removable data storage media, non-removable data storage media, and / or external storage devices available via a wired or wireless network architecture, where such computer program products include one or more database management products, web server products, application server products, and / or other additional software components. Examples of non-removable data storage media include internal magnetic hard drives, SSDs, etc. One or more memory devices 1206 can include volatile memory (e.g., dynamic random access memory (DRAM), static random access memory (SRAM), etc.) and / or non-volatile memory (e.g., read only memory (ROM), flash memory, etc.).

[0064] A computer program product containing mechanisms for implementing the systems and methods according to the techniques described in the present invention can reside in data storage device 1204 and / or memory device 1206, which can be referred to as machine-readable media. It should be understood that machine-readable media can include any tangible non-transitory medium capable of storing instructions or encoding them to perform any one or more of the operations of the present disclosure for a machine to execute, or any tangible non-transitory medium capable of storing data structures and / or modules utilized by or associated with such instructions or encoding them. The term "machine-readable media" can include a single medium or multiple media (e.g., centralized or distributed databases and / or associated caches and servers) that store one or more executable instructions or data structures.

[0065] In some embodiments, computer system 1200 includes one or more ports for communicating with other computing, networking, or vehicle devices, such as input / output (I / O) ports 1208, communication ports 1210, and subsystem ports 1212. It should be understood that ports 1208 through 1212 may be combined or separated, and more or fewer ports may be included in computer system 1200. I / O port 1208 may be connected to an I / O device or other device through which information is input to or output from computing system 1200. Such I / O devices may include, but are not limited to, one or more input devices, output devices, and / or environmental transducer devices.

[0066] In one embodiment, an input device converts a human-generated signal, such as a person's voice, body movement, physical touch, or pressure, into an electrical signal as input data that is input to computing system 1200 via I / O port 1208. In some instances, such input may be different from the various systems and methods discussed with respect to the previous figures. Similarly, an output device may convert an electrical signal received from computing system 1200 via I / O port 1208 into a signal that can be sensed or used by the various methods and systems discussed herein. The input device may be an alphanumeric input device that includes alphanumeric keys and other keys for transmitting information and / or command selections to processor 1202 via I / O port 1208.

[0067] An environmental transducer device converts one form of energy or signal into another form of energy or signal for input into or output from computing system 1200 via I / O port 1208. For example, an electrical signal generated within computing system 1200 may be converted into another type of signal, and / or vice versa. In one embodiment, the environmental transducer device senses characteristics or aspects of the environment local to or remote from computing device 1200, such as battery voltage, open-circuit battery voltage, charging current, battery temperature, light, sound, temperature, pressure, magnetic field, electric field, chemical properties, and the like.

[0068] In one embodiment, communication port 1210 may be connected to a network, and computer system 1200 may receive network data useful for performing the methods and systems described herein and transmitting the information and network configuration changes determined thereby via the network. For example, the charging protocol may be updated, battery measurement or calculated data may be shared with an external system, etc. Communication port 1210 connects computer system 1200 to one or more communication interface devices configured to transmit and / or receive information between computing system 1200 and other devices via one or more wired or wireless communication networks or connections. Examples of such networks or connections include, but are not limited to, Universal Serial Bus (USB), Ethernet, Wi-Fi, Near Field Communication (NFC), Long Term Evolution (LTE), etc. One or more such communication interface devices may be utilized via communication port 1210 to communicate directly with one or more other machines via a point-to-point communication path, via a Wide Area Network (WAN) (e.g., the Internet), via a Local Area Network (LAN), via a cellular (e.g., third generation (3G), fourth generation (4G), fifth generation (5G)) network, or via another communication component.

[0069] Computer system 1200 may include subsystem port 1212 for communicating with one or more systems related to charging a device according to the methods and systems described herein to control the operation of the device and / or exchange information between one or more subsystems of the device and computer system 1200. Examples of such subsystems of a vehicle include, but are not limited to, motor controllers and systems, battery control systems, etc.

[0070] Figure 12 The system described herein is only one possible example of a computer system that may be employed or configured in accordance with aspects of the present disclosure. It should be understood that other non-transitory tangible computer-readable storage media storing computer-executable instructions for implementing the techniques of the present disclosure on a computing system may be utilized.

[0071] Embodiments of the present disclosure include the various steps described in this specification. The steps may be performed by hardware components or may be embodied in machine-executable instructions that may be used to cause a general or special-purpose processor programmed with the instructions to perform the steps. Alternatively, the steps may be performed by a combination of hardware, software, and / or firmware.

[0072] Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. For example, while the embodiments described above, also referred to as implementations or examples, refer to specific features, the scope of the present invention also includes embodiments with different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the present invention is intended to cover all such alternatives, modifications, and variations, as well as all equivalents thereof.

[0073] Although specific implementations have been discussed, it should be understood that this is for illustrative purposes only. Those skilled in the relevant art will recognize that other components and configurations can be used without departing from the spirit and scope of the present disclosure. Accordingly, the following description and drawings are illustrative and should not be construed as restrictive. Many specific details have been described to provide a thorough understanding of the present disclosure. However, in some instances, well-known or conventional details have not been described so as not to obscure the description. A reference to one or an embodiment in the present disclosure can be a reference to the same embodiment or any embodiment; and such reference means at least one of the embodiments.

[0074] A reference to "an embodiment" or "one embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. The appearances of the phrase "in one embodiment" or similarly "in one instance" or "in one example" in various places in this specification are not necessarily all referring to the same embodiment, nor are they separate or alternative embodiments mutually exclusive of other embodiments. Additionally, various features are described that may be exhibited by some embodiments but not by others.

[0075] The terms used in this specification generally have their ordinary meaning in the context of the present disclosure and in the particular context in which each term is used. For any one or more of the terms discussed herein, alternative language and synonyms can be used, and no special significance should be attached thereto whether or not the term is elaborated or discussed in detail herein. In some cases, synonyms for certain terms are provided. The recitation of one or more synonyms does not exclude the use of other synonyms. The examples used anywhere in this specification (including examples of any of the terms discussed herein) are illustrative only and are not intended to further limit the scope and meaning of the present disclosure or any example term. Similarly, the present disclosure is not limited to the various embodiments given in this specification.

[0076] Without intending to limit the scope of the present disclosure, examples of instruments, devices, methods, and their related results according to embodiments of the present disclosure are given below. It should be noted that, for the convenience of the reader, headings or subheadings may be used in the examples, and they should in no way limit the scope of the present disclosure. Unless otherwise defined, technical terms and scientific terms used herein have the same meanings as those commonly understood by those of ordinary skill in the art to which the present disclosure pertains. In case of conflict, the present document (including the definitions) shall prevail.

[0077] Additional features and advantages of the present disclosure will be set forth in the following description and will be, to some extent, apparent from the description or can be learned by practicing the principles disclosed herein. The features and advantages of the present disclosure can be realized and obtained by the instruments and combinations particularly pointed out in the appended claims. These and other features of the present disclosure will become more apparent from the following description and the appended claims, or can be learned by practicing the principles set forth herein.

Claims

1. A battery charging method, comprising: Generating a series of charging signals, each charging signal in the series being at a period T, and each said charging signal including a shaped leading edge and a body portion that deliver charging energy to the battery; And Changing a duty cycle of the charging signal to change an average charging current delivered by a combination of the shaped leading edge and the body portion.

2. The battery charging method according to claim 1, further comprising: Shaping the shaped leading edge corresponding to a frequency and an impedance at the battery to the frequency.

3. The battery charging method according to claim 1, wherein when changing the duty cycle of the charging signal to change the average current, a maximum current of the charging signal is not changed.

4. The battery charging method according to claim 1, wherein changing the duty cycle is in response to a battery voltage.

5. The battery charging method according to claim 1, wherein changing the duty cycle is in response to a charge state.

6. The battery charging method according to claim 1, wherein changing the duty cycle is in response to a battery temperature.

7. The battery charging method according to claim 1, wherein the shaped leading edge and the body portion are followed by a rest period within the period T, and a maximum current of the rest period is less than a maximum current during the body portion.

8. The battery charging method according to claim 1, wherein the charging energy is sourced from a capacitor.

9. A method for charging an electrochemical device, the method comprising: Generating a charging signal including a shaped leading edge and a body portion that deliver charging energy to the battery, the charging signal having a first duty cycle and corresponding to a first average current within a signal period T; And After a first time period, changing the first duty cycle of the charging signal to a second duty cycle within the signal period T, the second duty cycle corresponding to a second average current of the charging signal, the second average current being different from the first average current within the signal period T.

10. The method according to claim 9, wherein changing the first duty cycle of the charging signal to the second duty cycle causes the second duty cycle to be less than the first duty cycle, and in response to the change of the first duty cycle, the second average current is less than the first average current within the signal period T.

11. The method according to claim 9, wherein changing the first duty cycle of the charging signal to the second duty cycle causes the second duty cycle to be greater than the first duty cycle, and in response to the change of the first duty cycle, the second average current is greater than the first average current within the signal period T.

12. The method according to claim 9, wherein changing the first duty cycle of the charging signal to the second duty cycle is in response to a voltage of the battery.

13. The method according to claim 9, wherein changing the first duty cycle of the charging signal to the second duty cycle is in response to a charge state of the battery.

14. The method according to claim 9, wherein changing the first duty cycle of the charging signal to the second duty cycle is in response to the temperature of the battery.

15. The method according to claim 9, further comprising: After a second time period, changing the second duty cycle of the charging signal to a third duty cycle within the signal period T, the third duty cycle corresponding to a third average current of the charging signal.

16. The method according to claim 9, further comprising: Maintaining the voltage of the charging signal during the first time period, the first average current decreasing in response to the maintained voltage of the charging signal.

17. The method according to claim 9, further comprising: Changing the charging signal to provide an average current close to zero to the battery within a time period to reduce the temperature of the battery.

18. The method according to claim 17, wherein changing the charging signal to provide the average current close to zero to the battery is in response to the temperature of the battery.

19. The method according to claim 17, wherein changing the first duty cycle of the charging signal to provide the average current close to zero to the battery is in response to the charge state of the battery.

20. The method according to claim 9, further comprising: Adjusting the duration of the period T, wherein the second average current corresponds to the adjustment of the duration of the period T.

21. The method according to claim 9, wherein the shaped leading edge and the body portion are followed by a rest period within the period T, the maximum current of the rest period being less than the maximum current during the body portion.

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