SYSTEMS AND METHODS FOR BATTERY CHARGING
Methods and systems for charging (recharging) one or more battery cells are presented by generating a harmonically tuned charge signal, which may involve pulses of a charge signal. The harmonically tuned charge signal includes or otherwise corresponds to a harmonic frequency or frequencies associated with an optimal transfer of energy based on a real and/or an imaginary value of the energy transfer of the battery cell. In one example, the harmonic frequency or frequencies, sometimes generally referred to as harmonics, may be associated with a minimum real impedance value of the battery cell. Aspects involve optimizing a charge signal corresponding to a harmonic, or harmonics, associated with minimum real or resistance and/or minimum imaginary or reactance impedance values of a battery cell. Such a charge signal may improve the efficiency when charging the battery cell by reducing lost energy due to high impedance at the electrodes of the battery cell.
1 . A method for charging an electrochemical device comprising:
accessing a harmonic profile that describes a relationship between at least one harmonic and an impedance of an electrochemical device; and
controlling an energy flux at an electrode of the electrochemical device, the energy flux at a harmonic associated with a minimum impedance value of the electrochemical device.
2 . The method of claim 1 , wherein the harmonic is associated with a minimum real impedance value of the electrochemical device.
3 . The method of claim 1 , wherein the harmonic is associated with a minimum imaginary impedance value of the electrochemical device.
4 . The method of claim 1 , wherein the harmonic is associated with a combination of a real impedance value and an imaginary impedance value of the electrochemical device.
5 . The method of claim 4 , wherein the harmonic is associated with a modulus combination of the real impedance value and the imaginary impedance value of the electrochemical device.
6 . The method of claim 4 , wherein the harmonic is associated with a combination of the real impedance value adjusted by a first weighted value and the imaginary impedance value adjusted by a second weighted value.
7 . The method of claim 1 , further comprising:
obtaining a change in the minimum impedance value; and
controlling the energy flux at the electrode of the electrochemical device at a new harmonic associated with the change in the minimum impedance value.
8 . The method of claim 7 wherein obtaining the change in the minimum impedance value comprises:
detecting a frequency associated with a parasitic loss of the electrochemical device; and
excluding a harmonic value associated with the detected frequency of the parasitic loss when obtaining the change in the minimum impedance value.
9 . The method of claim 1 wherein the electrochemical device comprises one of a half cell battery, a cell battery, a plurality of batteries connected in parallel, or a plurality of batteries connected in series.
10 . The method of claim 1 wherein the energy flux comprises one of a charge current, a discharge current, a charge voltage, a discharge voltage, a charge power, or a discharge power.
11 . The method of claim 1 , further comprising:
controlling a portion of the energy flux at a harmonic associated with conductance value of admittance or a susceptance value admittance of the electrochemical device.
12 . The method of claim 1 wherein the harmonic associated with the minimum impedance value comprises an upper frequency of a range of harmonics associated with the minimum impedance value.
13 . The method of claim 1 wherein the energy flux comprises a leading edge portion corresponding to the minimum impedance value of the electrochemical device.
14 . The method of claim 13 wherein the energy flux further comprises a body portion comprising a controlled magnitude value following the leading edge portion.
15 . The method of claim 14 wherein the energy flux further comprises a trailing edge portion comprising a voltage value below a transition voltage corresponding to a zero current flow at the electrochemical device.
16 . The method of claim 1 , further comprising:
measuring a real impedance value and imaginary impedance value of the electrochemical device during an application of the energy flux to the electrode of the electrochemical device.
17 . A method for charging an electrochemical device comprising:
accessing a harmonic profile that describes a relationship between at least one harmonic and an energy transfer of an electrochemical device; and
controlling an energy flux at an electrode of the electrochemical device, the energy flux at a harmonic associated with an optimal transfer of energy based on a real value and an imaginary value of the energy transfer at the electrode.
18 . The method for charging the electrochemical device of claim 17 wherein the real value of the energy transfer is a real impedance and the imaginary value of the energy transfer is an imaginary impedance.
19 . The method for charging the electrochemical device of claim 17 wherein the real value of the energy transfer is a conductance value and the imaginary value of the energy transfer is a susceptance value.
20 . A battery charging system comprising:
a charge signal shaping circuit; and
a controller, using a relationship between frequency components of a charge signal and impedance, controlling the charge signal shaping circuit to define an aspect of a charge signal for an electrochemical device based on the relationship between frequency components of charge signal and impedance.
21 . The battery charging system of claim 20 wherein the aspect of the charge signal is a leading edge of the charge signal.
22 . The battery charging system of claim 20 further comprising:
a power source providing a power signal and wherein controlling the charge signal shaping circuit comprises siphoning energy from the power signal to provide the charge signal.
23 . The battery charging system of claim 20 wherein the charge signal shaping circuit comprises:
one or more first shaping inductors in electrical communication to a power rail; and
a first switching device in electrical communication between the one or more first shaping inductors and an electrode of the electrochemical device.
24 . The battery charging system of claim 23 wherein the charge signal shaping circuit comprises:
one or more second shaping inductors in electrical communication to the electrode of the electrochemical device; and
a second switching device in electrical communication between the one or more second shaping inductors and the power rail.
25 . The battery charging system of claim 23 wherein the controller transmits a first control signal to the first switching device and a second control signal to the first switching device to shape the charge signal for the electrochemical device based on a harmonic associated with a minimum impedance value of the electrochemical device.
26 . The battery charging system of claim 23 , further comprising:
a power source in electrical communication with the power rail, wherein the power source is one of a voltage-controlled power source or a current-controlled power source.
27 . The battery charging system of claim 20 , further comprising:
an impedance measurement circuit in communication with the controller, the controller transmitting an impedance control signal to obtain an impedance measurement of the electrochemical device.
28 . A battery cell charging system comprising:
a charge signal shaping circuit comprising one or more inductors and a switching device, connected in series to the one or more inductors, the one or more inductors in electrical communication to a power rail, the switching device in electrical communication to a battery cell; and
a controller providing a control signal to the switching device to shape a charge signal from the power rail for a electrochemical device based on a harmonic associated with a minimum impedance of the electrochemical device.
29 . The battery cell charging system of claim 28 further comprising:
one or more second inductors in electrical communication to the battery cell; and
a second switching device in electrical communication with the one or more second inductors, the controller providing a pulse-width modified signal to activate the second switching device to further shape the charge signal.