Energy storage system for electric or hybrid vehicle

Abstract

A battery load leveling system for an electrically powered system in which a battery is subject to intermittent high current loading, the system including a first battery, a second battery, and a load coupled to the batteries. The system includes a passive storage device, a unidirectional conducting apparatus coupled in series electrical circuit with the passive storage device and poled to conduct current from the passive storage device to the load, the series electrical circuit coupled in parallel with the battery such that the passive storage device provides current to the load when the battery terminal voltage is less than voltage on the passive storage device, and a battery switching circuit that connects the first and second batteries in either a lower voltage parallel arrangement or a higher voltage series arrangement.

1. A battery load leveling system for an electrically powered system in which a battery is subject to intermittent high current loading, the electrically powered system including a first battery, a second, and a load coupled to the first and second batteries, said battery load leveling system comprising:
 a passive electrical energy storage device; 
 a unidirectional electrical conducting apparatus coupled to the passive storage device and to the load, and the unidirectional electrical coupling apparatus configured to conduct current only from the passive storage device to the load, and the passive storage device is in parallel with the first and second batteries to the load; and 
 a battery switching circuit that connects the first and second batteries in either a lower voltage parallel arrangement or a higher voltage series arrangement to allow a measurable terminal voltage of a circuit from the first and second batteries to the load to be switched from a first, higher voltage mode back and forth with a second lower voltage mode; and 
 when the battery switching circuit is in the second lower voltage mode, then the terminal voltage of the circuit from the first and second batteries to the load also is less than a measurable voltage of the passive storage device to the load, and the passive storage device responds to the battery switching circuit being in the second lower voltage mode by supplying electrical current to the load; and 
 further comprising a pre-charge circuit configured to charge said passive storage device using an external power source, 
 wherein said external power source comprises a hybrid vehicle engine that charges said passive storage device through an electrical circuit with the drive configured to accept regenerative power from the load. 
 
     
     
       2. A battery load leveling system in accordance with  claim 1  further comprising an electrical disconnect configured to disconnect said battery switching circuit from said passive storage device. 
     
     
       3. A battery load leveling system in accordance with  claim 2  further comprising a controller to selectively operate said electrical disconnect based on the voltage of said passive storage device and direction and magnitude of power flow from the load. 
     
     
       4. A battery load leveling system in accordance with  claim 1  wherein said battery switching circuit comprises a first contactor, a second contactor, and a third contactor, said first and second contactors operable to connect the first and second batteries in a lower voltage parallel arrangement, and said third contactor is operable to connect the first and second batteries in a higher voltage series arrangement. 
     
     
       5. A battery load leveling system in accordance with  claim 4  further comprising:
 a fourth contactor that is coupled in series with said first contactor; 
 a first apparatus for approximately simultaneously actuating said first and fourth contactors; and 
 a second apparatus for approximately simultaneously actuating said second and third contactor. 
 
     
     
       6. A battery load leveling system in accordance with  claim 5  wherein said second apparatus comprises a mechanical interlock that is coupled between said first and fourth contactors and said second and third contactors, said mechanical interlock configured to open said first and fourth contactors and approximately simultaneously close said second and third contactors to facilitate preventing a short circuit. 
     
     
       7. A battery load leveling system in accordance with  claim 5  further comprising a mechanical interlock configured to prevent switching said first and second batteries from a parallel arrangement to a series arrangement in the event of a fault including welded contacts. 
     
     
       8. A battery load leveling system in accordance with  claim 1  further comprising a first diode coupled in series with said first battery and a second diode coupled in series with said second battery such that when power flows from said first and second batteries to the load, said first and second batteries are arranged in the lower voltage parallel mode. 
     
     
       9. A battery load leveling system in accordance with  claim 8  further comprising an electrical disconnect that electrically connects said first and second batteries in a higher voltage series mode for either direction of power flow or current flow from the load. 
     
     
       10. A battery load leveling system in accordance with  claim 9  wherein said electrical disconnect is implemented using back-to-back silicon controlled rectifiers. 
     
     
       11. A battery load leveling system in accordance with  claim 9  wherein said electrical disconnect is implemented using a solid state switch. 
     
     
       12. A battery load leveling system in accordance with  claim 1  wherein said first and second batteries comprise at least one of a sodium nickel chloride battery and a sodium sulfur battery that are each operable at a temperature that is greater than 260 degrees Celsius. 
     
     
       13. A battery load leveling system in accordance with  claim 12  further comprising at least one electrical disconnect coupled in series with one or both terminals of each of said first and second batteries to allow galvanic isolation and to prevent leakage current flowing through said first and second batteries when in a cold or frozen state. 
     
     
       14. A battery load leveling system in accordance with  claim 1  further comprising a controller coupled to said battery switching circuit, said controller configured to connect said first and second batteries in either a lower voltage parallel arrangement or a higher voltage series arrangement based on at least one of a motor speed, a torque command, a passive storage device voltage, and a battery unit voltage. 
     
     
       15. A battery load leveling system in accordance with  claim 1  wherein said first and second batteries comprise at least one of a sodium nickel chloride battery, a sodium sulfur battery, a fuel cell, a nickel metal hydride battery, a lithium ion battery, a lithium polymer battery, a nickel cadmium battery, and a lead acid battery. 
     
     
       16. A battery load leveling system in accordance with  claim 1  wherein said unidirectional conducting apparatus comprises a diode. 
     
     
       17. An electric vehicle comprising a battery load leveling system as defined in  claim 1 . 
     
     
       18. A hybrid vehicle comprising: a battery load leveling system as defined in  claim 1 . 
     
     
       19. A battery load leveling system for an electrically powered system in which a battery is subject to intermittent high current loading, the electrically powered system including a first battery, a second, and a load coupled to the first and second batteries, said battery load leveling system comprising:
 a passive electrical energy storage device; 
 a unidirectional electrical conducting apparatus coupled to the passive storage device and to the load, and the unidirectional electrical coupling apparatus configured to conduct current only from the passive storage device to the load, and the passive storage device is in parallel with the first and second batteries to the load; and 
 a battery switching circuit that connects the first and second batteries in either a lower voltage parallel arrangement or a higher voltage series arrangement to allow a measurable terminal voltage of a circuit from the first and second batteries to the load to be switched from a first, higher voltage mode back and forth with a second lower voltage mode; and 
 when the battery switching circuit is in the second lower voltage mode, then the terminal voltage of the circuit from the first and second batteries to the load also is less than a measurable voltage of the passive storage device to the load, and the passive storage device responds to the battery switching circuit being in the second lower voltage mode by supplying electrical current to the load; and 
 further comprising a pre-charge circuit configured to charge said passive storage device using an external power source, 
 wherein said pre-charge circuit is configured to accept regenerative power from the load using a semiconductor switch. 
 
     
     
       20. A battery load leveling system in accordance with  claim 19  wherein said semiconductor switch comprises at least one of a silicon-controlled rectifier, a bipolar transistor, a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) and a Gate Turnoff Thyristor (GTO). 
     
     
       21. A battery load leveling system for an electrically powered system in which a battery is subject to intermittent high current loading, the electrically powered system including a first battery, a second, and a load coupled to the first and second batteries, said battery load leveling system comprising:
 a passive electrical energy storage device; 
 a unidirectional electrical conducting apparatus coupled to the passive storage device and to the load, and the unidirectional electrical coupling apparatus configured to conduct current only from the passive storage device to the load, and the passive storage device is in parallel with the first and second batteries to the load; and 
 a battery switching circuit that connects the first and second batteries in either a lower voltage parallel arrangement or a higher voltage series arrangement to allow a measurable terminal voltage of a circuit from the first and second batteries to the load to be switched from a first, higher voltage mode back and forth with a second lower voltage mode; and 
 when the battery switching circuit is in the second lower voltage mode, then the terminal voltage of the circuit from the first and second batteries to the load also is less than a measurable voltage of the passive storage device to the load, and the passive storage device responds to the battery switching circuit being in the second lower voltage mode by supplying electrical current to the load; and 
 further comprising a pre-charge circuit configured to charge said passive storage device using an external power source, 
 wherein said external power source comprises said first and second batteries, said battery switching circuit configured to couple said first and second batteries in either a lower voltage parallel arrangement or a higher voltage series arrangement. 
 
     
     
       22. A battery load leveling system in accordance with  claim 21  further comprising an electrical disconnect configured to disconnect said battery switching circuit from said passive storage device. 
     
     
       23. A battery load leveling system in accordance with  claim 22  further comprising a controller to selectively operate said electrical disconnect based on the voltage of said passive storage device and direction and magnitude of power flow from the load. 
     
     
       24. A battery load leveling system in accordance with  claim 21  wherein said battery switching circuit comprises a first contactor, a second contactor, and a third contactor, said first and second contactors operable to connect the first and second batteries in a lower voltage parallel arrangement, and said third contactor is operable to connect the first and second batteries in a higher voltage series arrangement. 
     
     
       25. A battery load leveling system in accordance with  claim 24  further comprising:
 a fourth contactor that is coupled in series with said first contactor; 
 a first apparatus for approximately simultaneously actuating said first and fourth contactors; and 
 a second apparatus for approximately simultaneously actuating said second and third contactor. 
 
     
     
       26. A battery load leveling system in accordance with  claim 25  wherein said second apparatus comprises a mechanical interlock that is coupled between said first and fourth contactors and said second and third contactors, said mechanical interlock configured to open said first and fourth contactors and approximately simultaneously close said second and third contactors to facilitate preventing a short circuit. 
     
     
       27. A battery load leveling system in accordance with  claim 25  further comprising a mechanical interlock configured to prevent switching said first and second batteries from a parallel arrangement to a series arrangement in the event of a fault including welded contacts. 
     
     
       28. A battery load leveling system in accordance with  claim 21  further comprising a first diode coupled in series with said first battery and a second diode coupled in series with said second battery such that when power flows from said first and second batteries to the load, said first and second batteries are arranged in the lower voltage parallel mode. 
     
     
       29. A battery load leveling system in accordance with  claim 28  further comprising an electrical disconnect that electrically connects said first and second batteries in a higher voltage series mode for either direction of power flow or current flow from the load. 
     
     
       30. A battery load leveling system in accordance with  claim 29  wherein said electrical disconnect is implemented using back-to-back silicon controlled rectifiers. 
     
     
       31. A battery load leveling system in accordance with  claim 29  wherein said electrical disconnect is implemented using a solid state switch. 
     
     
       32. A battery load leveling system in accordance with  claim 21  wherein said first and second batteries comprise at least one of a sodium nickel chloride battery and a sodium sulfur battery that are each operable at a temperature that is greater than 260 degrees Celsius. 
     
     
       33. A battery load leveling system in accordance with  claim 32  further comprising at least one electrical disconnect coupled in series with one or both terminals of each of said first and second batteries to allow galvanic isolation and to prevent leakage current flowing through said first and second batteries when in a cold or frozen state. 
     
     
       34. A battery load leveling system in accordance with  claim 21  further comprising a controller coupled to said battery switching circuit, said controller configured to connect said first and second batteries in either a lower voltage parallel arrangement or a higher voltage series arrangement based on at least one of a motor speed, a torque command, a passive storage device voltage, and a battery unit voltage. 
     
     
       35. A battery load leveling system for an electrically powered system in which a battery is subject to an intermittent high current loading, the system including a first battery, a second battery, and a load coupled to the first and second batteries, the system comprising:
 a passive storage device;   a unidirectional conducting apparatus coupled in a series circuit with the passive storage device and poled to conduct current from the passive storage device to the load, the series circuit coupled in parallel with the first and second batteries;   a battery switching circuit that connects the first and second batteries in a lower voltage parallel arrangement and a higher voltage series arrangement;   a controller configured to automatically switch the first and second batteries between the lower voltage parallel arrangement and the higher voltage series arrangement; and   a contactor in series with at least one of the first and second batteries.   
     
     
       36. The battery load leveling system of claim 35 comprising a diode in series with at least one of the first and second batteries. 
     
     
       37. The battery load leveling system of claim 35 wherein the passive storage device is configured to provide current to the load when a battery terminal voltage is less than a voltage on the passive storage device. 
     
     
       38. The battery load leveling system of claim 35 wherein the battery switching circuit comprises at least one semiconductor switch. 
     
     
       39. The battery load leveling system of claim 38 wherein the at least one semiconductor switch includes a silicon controlled rectifier. 
     
     
       40. A battery load leveling system for an electrically powered system in which a battery is subject to an intermittent high current loading, the system including a first battery, a second battery, and a load coupled to the first and second batteries, the system comprising:
 a passive storage device;   a unidirectional conducting apparatus coupled in a series circuit with the passive storage device and poled to conduct current from the passive storage device to the load, the series circuit coupled in parallel with the first and second batteries;   a battery switching circuit that connects the first and second batteries in a lower voltage parallel arrangement and a higher voltage series arrangement; and   a controller configured to automatically switch the first and second batteries between the lower voltage parallel arrangement and the higher voltage series arrangement;   wherein the battery switching circuit is free of a mechanical switching device; and   wherein the controller is configured to switch between the lower voltage parallel arrangement and the higher voltage series arrangement based on one of a vehicle speed, a motor torque, and a motor speed.   
     
     
       41. The battery load leveling system of claim 40 comprising a contactor and a diode in series with at least one of the first and second batteries. 
     
     
       42. The battery load leveling system of claim 40 wherein at least one of the first and second batteries comprises one of a nickel metal hydride battery, a lithium polymer battery, a nickel cadmium battery, and a lead acid battery. 
     
     
       43. The battery load leveling system of claim 40 wherein the passive storage device is configured to provide current to the load when a battery terminal voltage is less than a voltage on the passive storage device. 
     
     
       44. A battery load leveling system for an electrically powered system in which a battery is subject to an intermittent high current loading, the system including a first battery, a second battery, and a load coupled to the first and second batteries, the system comprising:
 a passive storage device coupled in parallel with the first and second batteries;   a battery switching circuit that connects the first and second batteries in a lower voltage parallel arrangement and a higher voltage series arrangement, wherein the battery switching circuit comprises at least one silicon controlled rectifier; and   a controller coupled to the battery switching circuit, the controller configured to connect the first and second batteries in either a lower voltage parallel arrangement or a higher voltage series arrangement based on at least one of a motor speed, a torque command, a passive storage device voltage, and a battery unit voltage.   
     
     
       45. The battery load leveling system of claim 44 comprising a unidirectional conducting apparatus coupled in a series circuit with the passive storage device and poled to conduct current from the passive storage device to the load. 
     
     
       46. The battery load leveling system of claim 44 wherein the passive storage device is configured to provide current to the load when a battery terminal voltage is less than a voltage on the passive storage device. 
     
     
       47. A battery load leveling system for an electrically powered system in which a battery is subject to an intermittent high current loading, the system including a first battery, a second battery, and a load coupled to the first and second batteries, the system comprising:
 a passive storage device;   a unidirectional conducting apparatus coupled in a series circuit with the passive storage device and poled to conduct current from the passive storage device to the load, the series circuit coupled in parallel with the first and second batteries;   a battery switching circuit that connects the first and second batteries in a lower voltage parallel arrangement and a higher voltage series arrangement; and   a controller configured to automatically switch the first and second batteries between the lower voltage parallel arrangement and the higher voltage series arrangement;   wherein the controller is configured to implement a time delay to enable a parallel mode contactor to be opened prior to a series mode contactor being closed.   
     
     
       48. A battery load leveling system for an electrically powered system in which a battery is subject to an intermittent high current loading, the system including a first battery, a second battery, and a load coupled to the first and second batteries, the system comprising:
 a passive storage device;   a unidirectional conducting apparatus coupled in a series circuit with the passive storage device and poled to conduct current from the passive storage device to the load, the series circuit coupled in parallel with the first and second batteries;   a battery switching circuit that connects the first and second batteries in a lower voltage parallel arrangement and a higher voltage series arrangement; and   a controller configured to automatically switch the first and second batteries between the lower voltage parallel arrangement and the higher voltage series arrangement;   wherein the controller is configured to switch between the lower voltage parallel arrangement and the higher voltage series arrangement based on one of a vehicle speed, a motor torque, and a motor speed.   
     
     
       49. A battery load leveling system for an electrically powered system in which a battery is subject to an intermittent high current loading, the system including a first battery, a second battery, and a load coupled to the first and second batteries, the system comprising:
 a passive storage device;   a unidirectional conducting apparatus coupled in a series circuit with the passive storage device and poled to conduct current from the passive storage device to the load, the series circuit coupled in parallel with the first and second batteries;   a battery switching circuit that connects the first and second batteries in a lower voltage parallel arrangement and a higher voltage series arrangement;   a controller configured to automatically switch the first and second batteries between the lower voltage parallel arrangement and the higher voltage series arrangement; and   a switch that couples the load to the series circuit;   wherein the controller is configured to activate the switch such that current flows from the load, when the electrically powered system is operated in a regenerative braking mode, to the passive storage device, such that a voltage across the passive storage device is greater than a voltage across a parallel arrangement of the first and second batteries.   
     
     
       50. A battery load leveling system for an electrically powered system in which a battery is subject to an intermittent high current loading, the system including a first battery, a second battery, and a load coupled to the first and second batteries, the system comprising:
 a passive storage device;   a unidirectional conducting apparatus coupled in a series circuit with the passive storage device and poled to conduct current from the passive storage device to the load, the series circuit coupled in parallel with the first and second batteries;   a battery switching circuit that connects the first and second batteries in a lower voltage parallel arrangement and a higher voltage series arrangement;   a controller configured to automatically switch the first and second batteries between the lower voltage parallel arrangement and the higher voltage series arrangement; and   a main contactor coupled between the first and second batteries and the load, wherein the controller operates the main contactor based on a voltage difference between a voltage on the parallel battery arrangement and a voltage on the passive storage device.   
     
     
       51. The battery load leveling system of claim 50 wherein the controller is configured to operate the main contactor based on an amount of regenerative braking of the electrically powered system. 
     
     
       52. A battery load leveling system for an electrically powered system in which a battery is subject to an intermittent high current loading, the system including a first battery, a second battery, and a load coupled to the first and second batteries, the system comprising:
 a passive storage device;   a unidirectional conducting apparatus coupled in a series circuit with the passive storage device and poled to conduct current from the passive storage device to the load, the series circuit coupled in parallel with the first and second batteries;   a battery switching circuit that connects the first and second batteries in a lower voltage parallel arrangement and a higher voltage series arrangement; and   a controller configured to automatically switch the first and second batteries between the lower voltage parallel arrangement and the higher voltage series arrangement;   wherein the controller is configured to maintain the parallel arrangement of the first and second batteries during a regenerative braking event of the electrically powered system based on a voltage level generated from the regenerative braking event.   
     
     
       53. A battery load leveling system for an electrically powered system in which a battery is subject to an intermittent high current loading, the system including a first battery, a second battery, and a load coupled to the first and second batteries, the system comprising:
 a passive storage device;   a unidirectional conducting apparatus coupled in a series circuit with the passive storage device and poled to conduct current from the passive storage device to the load, the series circuit coupled in parallel with the first and second batteries;   a battery switching circuit that connects the first and second batteries in a lower voltage parallel arrangement and a higher voltage series arrangement;   a controller configured to automatically switch the first and second batteries between the lower voltage parallel arrangement and the higher voltage series arrangement; and   a pre-charge circuit configured to charge the passive storage device.   
     
     
       54. A battery load leveling system for an electrically powered system in which a battery is subject to an intermittent high current loading, the system including a first battery, a second battery, and a load coupled to the first and second batteries, the system comprising:
 a passive storage device;   a unidirectional conducting apparatus coupled in a series circuit with the passive storage device and poled to conduct current from the passive storage device to the load, the series circuit coupled in parallel with the first and second batteries;   a battery switching circuit that connects the first and second batteries in a lower voltage parallel arrangement and a higher voltage series arrangement; and   a controller configured to automatically switch the first and second batteries between the lower voltage parallel arrangement and the higher voltage series arrangement   wherein the battery switching circuit is free of a mechanical switching device; and   wherein the controller is configured to implement a time delay to enable a parallel mode operation of the battery switching circuit to be implemented prior to a series mode operation of the battery switching circuit being closed.   
     
     
       55. A battery load leveling system for an electrically powered system in which a battery is subject to an intermittent high current loading, the system including a first battery, a second battery, and a load coupled to the first and second batteries, the system comprising:
 a passive storage device;   a unidirectional conducting apparatus coupled in a series circuit with the passive storage device and poled to conduct current from the passive storage device to the load, the series circuit coupled in parallel with the first and second batteries;   a battery switching circuit that connects the first and second batteries in a lower voltage parallel arrangement and a higher voltage series arrangement;   a controller configured to automatically switch the first and second batteries between the lower voltage parallel arrangement and the higher voltage series arrangement; and   a switch that couples the load to the series circuit;   wherein the battery switching circuit is free of a mechanical switching device; and   wherein the controller is configured to activate the switch such that current flows from the load, when the electrically powered system is operated in a regenerative braking mode, to the passive storage device, such that a voltage across the passive storage device is greater than a voltage across a parallel arrangement of the first and second batteries.   
     
     
       56. A battery load leveling system for an electrically powered system in which a battery is subject to an intermittent high current loading, the system including a first battery, a second battery, and a load coupled to the first and second batteries, the system comprising:
 a passive storage device;   a unidirectional conducting apparatus coupled in a series circuit with the passive storage device and poled to conduct current from the passive storage device to the load, the series circuit coupled in parallel with the first and second batteries;   a battery switching circuit that connects the first and second batteries in a lower voltage parallel arrangement and a higher voltage series arrangement;   a controller configured to automatically switch the first and second batteries between the lower voltage parallel arrangement and the higher voltage series arrangement; and   a main contactor coupled between the first and second batteries and the load that is switchable based on a voltage difference between a voltage on the lower voltage parallel battery arrangement and a voltage on the passive storage device;   wherein the battery switching circuit is free of a mechanical switching device.   
     
     
       57. The battery load leveling system of claim 56 wherein the controller is configured to operate the main contactor based on an amount of regenerative braking of the electrically powered system. 
     
     
       58. A battery load leveling system for an electrically powered system in which a battery is subject to an intermittent high current loading, the system including a first battery, a second battery, and a load coupled to the first and second batteries, the system comprising:
 a passive storage device;   a unidirectional conducting apparatus coupled in a series circuit with the passive storage device and poled to conduct current from the passive storage device to the load, the series circuit coupled in parallel with the first and second batteries;   a battery switching circuit that connects the first and second batteries in a lower voltage parallel arrangement and a higher voltage series arrangement; and   a controller configured to automatically switch the first and second batteries between the lower voltage parallel arrangement and the higher voltage series arrangement; and   wherein the battery switching circuit is free of a mechanical switching device; and   wherein the controller is configured to maintain the lower voltage parallel arrangement of the first and second batteries during regenerative braking of the electrically powered system based on a voltage level generated from the regenerative braking.