Excessive current detection controls method
First Claim
1. A method for controlling charging and discharging power in a battery pack, said method comprising:
- measuring current flowing into or out of the battery pack with a current sensor;
establishing a threshold value for current for each time window of a plurality of time windows, where the threshold value is lower for longer time windows;
calculating a root mean square current for each time window of the plurality of time windows from the measured current;
comparing the root mean square current for each time window of the plurality of time windows to the threshold value for the time window; and
controlling the charging or discharging power if the root mean square current for any of the plurality of time windows exceeds the threshold value for the time window.
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Accused Products
Abstract
A method for controlling charging and discharging of a battery pack for an electric or hybrid vehicle to prevent overheating damage. Current flowing into or out of the battery pack is monitored, and root mean square (RMS) current is integrated over a time window and compared to a threshold to determine if power needs to be regulated in order to prevent damage to the cells in the battery pack. If the time-integrated RMS current exceeds the threshold, a closed-loop proportional-integral (PI) controller is activated to regulate power input or output. The controller will continue to regulate power until the time-integrated RMS current drops below the threshold. Various thresholds can be defined for different time windows. The gains used in the PI controller can also be adjusted to scale the amount of power regulation.
22 Citations
20 Claims
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1. A method for controlling charging and discharging power in a battery pack, said method comprising:
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measuring current flowing into or out of the battery pack with a current sensor; establishing a threshold value for current for each time window of a plurality of time windows, where the threshold value is lower for longer time windows; calculating a root mean square current for each time window of the plurality of time windows from the measured current; comparing the root mean square current for each time window of the plurality of time windows to the threshold value for the time window; and controlling the charging or discharging power if the root mean square current for any of the plurality of time windows exceeds the threshold value for the time window. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for controlling charging and discharging power in a lithium-ion battery pack in an electric vehicle, said method comprising:
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measuring current flowing into or out of the battery pack with a current sensor; establishing a threshold value for current for each time window of a plurality of time windows, where the threshold value is lower for longer time windows; calculating a rolling average root mean square current for each time window of the plurality of time windows from the measured current; comparing the rolling average root mean square current for each time window of a plurality of time windows to the threshold value for the time window; and controlling the charging or discharging power, where the charging or discharging power is reduced if the rolling average root mean square current for any of the plurality of time windows exceeds the threshold value for the time window. - View Dependent Claims (11, 12, 13, 14)
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15. A power management system for a battery pack providing electrical energy to an apparatus, said power management system comprising:
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a current sensor for measuring current flowing into or out of the battery pack; a controller for managing charging and discharging power in the battery pack, said controller being responsive to measurement signals from the current sensor and being configured to limit the power to prevent damage to the battery pack if the current, averaged over each time window of a plurality of time windows, exceeds a threshold value for the time window, where the threshold value is lower for longer time windows; and means for limiting charging and discharging power in the battery pack in response to signals from the controller. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification