Abstract: A smart cell, comprising: a positive terminal; a negative terminal; a switching circuit which is arranged to select between a first switching state in which an energy storage device is connected between the positive terminal and the negative terminal and a second switching state which bypasses said energy storage device; an inductor provided between the positive terminal and the output of the switching network; and a controller arranged to monitor the voltage across the inductor and arranged to control a duty cycle of the switching circuit based on the magnitudes of voltage changes detected across the inductor. By monitoring and analysing the magnitude of voltage changes across the inductor, the controller determines the states of charge of other series connected smart cells without any communication between cells.

Abstract: A smart cell, comprising: a positive terminal; a negative terminal; a switching circuit which is arranged to select between a first switching state in which an energy storage device is connected between the positive terminal and the negative terminal and a second switching state in which bypasses said energy storage device; and an inductor provided between the positive terminal and the negative terminal. The inductor provides a means by which to monitor current changes in the rest of the circuit. The inductor can thus be used to detect current changes as seen by the smart cell and this sensed information can be used to control the smart cell, e.g. to control an energy source (energy storage device) that forms part of the smart cell. As the inductor is part of the smart cell, it forms part of a decentralized controller strategy to regulate the state of charge of cells within a larger system.

Abstract: A smart cell, comprising: a positive terminal; a negative terminal; a switching circuit which is arranged to select between a first switching state in which an energy storage device is connected between the positive terminal and the negative terminal and a second switching state which bypasses said energy storage device; an inductor provided between the positive terminal and the output of the switching network; and a controller arranged to monitor the voltage across the inductor and arranged to control a duty cycle of the switching circuit based on the magnitudes of voltage changes detected across the inductor. By monitoring and analysing the magnitude of voltage changes across the inductor, the controller determines the states of charge of other series connected smart cells without any communication between cells.

Abstract: A method of estimating a battery state includes acquiring one or more parameters for estimating a present state of the battery based on a previous state of the battery; acquiring a present usage environment of the battery; and estimating the present state by applying any one or any combination of any two or more of the previous state, the present usage environment, and the acquired one or more parameters to an electrochemical model that is expressed by simplified parameters simplified by either one or both of parameter grouping and partial non-dimensionalising of an electrochemical reaction governing equation of the battery.

Abstract: An electrical energy storage device includes a plurality of energy cell slots for receiving energy cells; and a controller; wherein the controller is arranged to estimate a characteristic of a cell in each slot; and wherein the controller is arranged to apply charge and discharge currents to each cell slot dependent upon at least one estimated characteristic currently associated with that slot. The controller may be a single controller that controls all slots or it may be implemented as multiple controllers each controlling more than one cell slot or a controller for each slot. The characteristic may be one or more of: a power capability, a storage capacity, a cell impedance, an energy cell type and an energy cell chemistry.

Abstract: A smart cell, comprising: a positive terminal; a negative terminal; a switching circuit which is arranged to select between a first switching state in which an energy storage device is connected between the positive terminal and the negative terminal and a second switching state in which bypasses said energy storage device; and an inductor provided between the positive terminal and the negative terminal. The inductor provides a means by which to monitor current changes in the rest of the circuit. The inductor can thus be used to detect current changes as seen by the smart cell and this sensed information can be used to control the smart cell, e.g. to control an energy source (energy storage device) that forms part of the smart cell. As the inductor is part of the smart cell, it forms part of a decentralized controller strategy to regulate the state of charge of cells within a larger system.

Abstract: A method of estimating a battery state includes acquiring one or more parameters for estimating a present state of the battery based on a previous state of the battery; acquiring a present usage environment of the battery; and estimating the present state by applying any one or any combination of any two or more of the previous state, the present usage environment, and the acquired one or more parameters to an electrochemical model that is expressed by simplified parameters simplified by either one or both of parameter grouping and partial non-dimensionalising of an electrochemical reaction governing equation of the battery.

Abstract: An electrical energy storage device includes a plurality of energy cell slots for receiving energy cells; and a controller; wherein the controller is arranged to estimate a characteristic of a cell in each slot; and wherein the controller is arranged to apply charge and discharge currents to each cell slot dependent upon at least one estimated characteristic currently associated with that slot. The controller may be a single controller that controls all slots or it may be implemented as multiple controllers each controlling more than one cell slot or a controller for each slot. The characteristic may be one or more of: a power capability, a storage capacity, a cell impedance, an energy cell type and an energy cell chemistry.

Abstract: A method for monitoring the condition of at least one cell of a battery, used in an electric or hybrid electric vehicle. The battery is connected to a power converter to supply electrical power to an electrical load. The method includes the steps of: controlling the power converter to vary the input impedance of the power converter to draw a varying current from the cell; sensing the voltage across the cell and the current drawn in response to varying the impedance of the power converter; calculating from the sensed voltage and current the complex impedance of the cell; and comparing the calculated complex impedance with information indicative of a correlation between (i) the complex impedance and (ii) information indicative of the condition of the cell, to give an indication of the condition of the cell. The varying current may be actively varied or passively varied.