Methods and apparatus for heating and self-heating of batteries at low temperatures

Abstract

A heating circuit including: a resonance circuit couplable to an energy storage device for providing alternating between a positive input current and a negative input current at the energy storage device when coupled to the energy storage device, wherein the positive input current flows in to the energy storage device and the negative input current flows out of the energy storage device, wherein the resonance circuit provides the alternating stepwise at the energy storage device, with a step between the positive input current and the negative input current wherein no positive input current and negative input current is provided; a controller that controls the resonance circuit to provide the alternating, and the resonance circuit provides the alternating positive and negative input currents at a frequency sufficient to effectively short the internal surface capacitance of the energy storage device to generate heat and raise a temperature of the electrolyte.

What is claimed is: 
     
         1 . A heating circuit for generating heat when coupled to an energy storage device having a core with an electrolyte, the energy storage device having inputs and internal surface capacitance between the inputs which can store electric field energy between internal electrodes of the energy storage device that are coupled to the inputs, the heating circuit comprising:
 a resonance circuit couplable to the energy storage device, wherein the resonance circuit is configured to provide alternating between a positive input current and a negative input current at the energy storage device when coupled to the energy storage device, wherein the positive input current flows in to the energy storage device and the negative input current flows out of the energy storage device, wherein the resonance circuit is configured to provide the alternating between the positive input current and the negative input current stepwise at the energy storage device, with a step between the positive input current and the negative input current wherein no positive input current and negative input current is provided;   a controller configured to control the resonance circuit to provide the alternating between the positive input current and the negative input current at the energy storage device, and   wherein the resonance circuit is configured to provide the alternating positive and negative input currents at a frequency sufficient to effectively short the internal surface capacitance of the energy storage device to generate heat and raise a temperature of the electrolyte.   
     
     
         2 . The heating circuit of  claim 1 , wherein the controller is configured to control the resonance circuit to repeatedly provide the alternating positive and negative input currents at the energy storage device and is configured to discontinue the repeated alternating positive and negative input currents when the temperature of the electrolyte and/or the energy storage device is within an operational temperature range of the energy storage device. 
     
     
         3 . The heating circuit of  claim 1 , wherein the controller is configured to start the resonance circuit to provide the alternating positive and negative input currents at the one of the inputs when the temperature of the electrolyte and/or the energy storage device is lower than an operational temperature range of the energy storage device. 
     
     
         4 . The circuit of  claim 1 , comprising a switching network,
 wherein the controller is controller is configured to provide the alternating positive and negative input currents at the energy storage device through control of the switching network.   
     
     
         5 . The heating circuit of  claim 1 , comprising a temperature sensor configured to provide a signal to the controller, wherein the signal is based on a sensed temperature of the electrolyte and/or a surface of the energy storage device, and wherein the controller is configured to start and stop the resonance circuit to provide the alternating positive and negative input currents at the one of the inputs in response to the signal. 
     
     
         6 . The heating circuit of  claim 1 , comprising a switch, wherein the resonance circuit comprises a component configured to be charged by the energy storage device through the switch, and wherein the controller is configured to control the switch to start and discontinue heating of the electrolyte. 
     
     
         7 . The heating circuit of  claim 6 , wherein the switch is a first switch, the heating circuit comprising a second switch coupled to the component, wherein the second switch is configured to initiate discharging of the component, and wherein the controller is configured to control the second switch to start and discontinue discharging of the component. 
     
     
         8 . The heating circuit of  claim 7 , wherein the controller is configured to control the first switch to discontinue charging of the component after the component is charged to a potential of the voltage source and is thereafter configured to control the second switch to start discharging of the component. 
     
     
         9 . The heating circuit of  claim 7 , the heating circuit comprising a resistor coupled between the second switch and the component, and wherein the heating circuit is configured such that when the second switch is controlled to start discharging of the component, the discharging occurs through the resistor. 
     
     
         10 . The heating circuit of  claim 9 , wherein the resistor is configured to be positioned in proximity to the energy storage device such that heat generated by the resistor during discharging of the component through the resistor heats the energy storage device. 
     
     
         11 . The heating circuit of  claim 7 , the resonance circuit comprising an inductor coupled between the component and the energy storage device when coupled to the energy storage device, and wherein the resonance circuit is configured such that when the second switch is controlled to start discharging of the component, the discharge transfers a charge to the inductor. 
     
     
         12 . The heating circuit of  claim 11 , wherein the controller is configured to close the second switch to control the discharge of the component and is configured to open the second switch after the charge from the component has been transferred to the inductor and the charge from the inductor has been transferred back to the component by a resonant transfer. 
     
     
         13 . The heating circuit of  claim 1 , comprising a capacity sensor configured to provide an indication of a capacity of the energy storage device, wherein the controller is configured to enable and disable heating based on the indication of the capacity. 
     
     
         14 . The heating circuit of  claim 13 , wherein, when heating is enabled, the controller is configured to start the resonance circuit to provide the alternating positive and negative input currents at the energy storage device in response to a predetermined temperature that is lower than an operational temperature range of the energy storage device. 
     
     
         15 . A heating circuit for generating heat when coupled to an energy storage device having a core with an electrolyte, the energy storage device having inputs and internal surface capacitance between the inputs which can store electric field energy between internal electrodes of the energy storage device that are coupled to the inputs, the heating circuit comprising:
 a resonance circuit couplable to the energy storage device, wherein the resonance circuit is configured to provide a positive input current and a negative input current at the energy storage device when coupled to the energy storage device, wherein the positive input current flows in to the energy storage device and the negative input current flows out of the energy storage device;   a controller configured to
 periodically obtain a measurement that correlates to the temperature of the electrolyte, and 
 control the resonance circuit to provide alternating positive and negative input currents at the energy storage device at a frequency sufficient to effectively short the internal surface capacitance of the energy storage device to generate heat and raise a temperature of the electrolyte when the measurement indicates that the temperature of the electrolyte is below an operational temperature of the energy storage device; 
   a first switch, wherein the resonance circuit comprises a component configured to be charged by the energy storage device through operation of the first switch, and wherein the controller is configured to control the first switch to start and discontinue heating of the electrolyte;   a second switch coupled to the component, wherein the second switch is configured to initiate discharging of the component, and wherein the controller is configured to control the second switch to start and discontinue discharging of the component,   wherein the controller is configured to close the first switch to capture information indicating voltage and current waveforms of the energy storage device when coupled to the energy storage device; and   an inductor coupled between the energy storage device and the component,   wherein when the second switch is coupled to control the discharge of the component with the discharge transferring a charge to the inductor.   
     
     
         16 . The heating circuit of  claim 15 , wherein the controller is configured to control the resonance circuit to repeatedly provide the alternating positive and negative input currents at the energy storage device and the controller is configured to discontinue the alternating positive and negative input currents when the temperature of the electrolyte and/or the energy storage device is within the operational temperature range of the energy storage device. 
     
     
         17 . The heating circuit of  claim 15 , the resonance circuit comprising a chargeable component, wherein the controller is configured to control discharging the chargeable component when the chargeable component is charged to a voltage of the energy storage device as a result of the alternating positive and negative input currents.