Device and method for stabilizing a battery pack

• US 8,598,846 B1
• Filed: 04/07/2010
• Issued: 12/03/2013
• Est. Priority Date: 04/07/2009
• Status: Expired due to Fees

• Current Assignee: University of Akron
• Original Assignee: University of Akron
• Inventors: Hartley, Thomas T., Magistro, Benjamin, Vo, Thomas
• Primary Examiner(s): Muralidar, Richard V
• Assistant Examiner(s): Chung, Steve T
• Application Number:
  US12/756,107
• Time in Patent Office: 1,336 Days
• Field of Search: 320/118, 320/122, 320/124, 320/127, 320/119, 320/120, 429/56, 361 54- 61
• US Class Current: 320/122
• CPC Class Codes: B60L 2240/36 Temperature of vehicle components or parts
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 2240/80 Time limits
• CPC Class Codes: B60L 3/12 Recording operating variables ; Monitoring of operating variables
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 58/22 Balancing the charge of battery modules
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/0047 with monitoring or indicating devices or circuits
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/92 Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles

Abstract

The present invention generally relates to a device and method for stabilizing a battery pack, wherein the battery pack stabilization device has a by-pass circuit to prevent individual cell overcharge. In one embodiment, the present invention relates to an efficient balancing and monitoring system for use in an electric vehicle that utilizes nickel-zinc-based batteries. In another embodiment, the present invention relates to a device that permits over-voltage protection as well as the ability to monitor cell voltage. In still another embodiment, the present invention provides a method to coordinate multiple packs of cells within a vehicle so a driver could be aware of possible distance and time parameters, as well as a monitoring or alert system to inform the driver of reduced power, thus preventing damage to the cells.

Claims

1. A device for stabilizing a battery cell comprises:

a comparator having an input and an output, wherein said input is configured to monitor the voltage of the battery cell in comparison to a reference voltage;

a series coupled potentiometer and a first resistor adapted to be coupled in parallel with the battery cell, wherein said input is coupled to a node between said potentiometer and said first resistor, such that said potentiometer is adjusted to set a voltage across said first resistor based on the battery cell type;

a first transistor having an input and an output, such that said input of said first transistor is coupled to said output of said comparator, such that the output of said comparator controls the on and off state of said output of said first transistor; and

a second transistor having an input and an output, such that said input of said second transistor is coupled to said output of said first transistor to control the on and off state of said output of said second transistor, and said output of said second transistor is coupled in series with a second resistor, wherein said input of said second transistor and said second resistor are in parallel with said output of said first transistor, and wherein the battery is coupled in parallel with the output of said second transistor and said second resistor;

wherein when said comparator detects that said voltage across said first resistor is approximately greater than or equal to said reference voltage, said first transistor is turned on by said output of said comparator, and said second transistor is turned on by said output of said first transistor, such that electrical current applied to the battery cell is shunted away from the battery cell and through said output of said second transistor to said second resistor.

2. The device of claim 1, further comprising a potentiometer coupled to said input of said comparator to adjust said reference voltage.

3. The device of claim 1, further comprising:

an opto-isolator having an input coupled to said input of said comparator; and

a controller coupled to said opto-isolator, said controller configured to place said opto-isolator into either of an on or off state, such that when said opto-isolator is turned off, the device is disabled, and when said opto-isolator is turned on the device is enabled.

4. A method for stabilizing a plurality of battery cells comprises the steps of:

providing a stabilizing circuit having a charging path carrying electrical current to each battery cell coupled thereto, said stabilizing circuit including a bypass path associated with each battery cell coupled to said charging path, wherein each said charging path includes a series coupled resistor and a potentiometer that are in parallel with each battery cell;

adjusting at least one potentiometer to set a voltage across at least one said resistor based on the battery cell type;

providing a controller coupled to said stabilizing circuit to monitor the voltage of each battery cell as said charging circuit charges the battery cells;

determining whether the voltage of each battery cell is approximately greater than or equal to a reference voltage by said monitoring circuit; and

shunting the electrical current from said charging path to said bypass path associated with each battery cell having a voltage that is approximately greater than or equal to said reference voltage.

5. The method of claim 4, further comprising the step of:

providing an opto-isolator coupled to said stabilizing circuit to place said stabilizing circuit into either of an activated or inactivated state.