Battery management system with temperature sensing and charge management for individual series-connected battery cells
A method and apparatus are disclosed for a Battery Management System (BMS) for the controlling of the charging and discharging of a plurality of battery cells ( 12 ). Each battery cell has an associated plurality of control circuits ( 32, 36 ) which monitor and control the charging of individual battery cells. These units are controlled by a central microcontroller ( 14 ) which shunts current around the battery cell if fully charged and stops discharge if a battery cell is fully discharged in order to prevent damage to the other cells.
1. A modular battery management system for controlling and monitoring a plurality of battery cells connected in series in a battery connected to a load, the modular battery management system comprising:
a plurality of battery monitoring modules, each of the battery monitoring modules including a cell balancing means, a slave sensing means, and at least one temperature sensor operable to monitor the temperature of said cell balancing means and said slave sensing means to determine if an excessive temperature has been reached during operation of said cell balancing means and said slave sensing means; and
a central controlling microcontroller operatively connected to each of the plurality of battery monitoring modules and configured for controlling each of the plurality of battery monitoring modules;
each of the battery monitoring modules being operatively connected to one or more of said plurality of battery cells such that each individual battery cell of the plurality of battery cells has an electric connection to one of the plurality of battery monitoring modules, whereby each of the plurality of battery monitoring modules is operable to:
(a) measure a charging state of a respective battery cell;
(b) when a maximum charging state is reached in the respective battery cell, establish a shunt across the respective battery cell that has reached the maximum charging state, thereby allowing a continued charging of remaining battery cells in the plurality of battery cells;
(c) when the shunt is established, communicate to the central controlling microcontroller that the maximum charging state has been reached in the respective battery cell in which the maximum charging state has been reached;
(d) shut down charging of the battery when the excessive temperature is reached; and
(e) during discharging of the battery, to inform the central controlling microcontroller when a non-zero minimum voltage has been reached in the respective battery cell so as to cause the central controlling microcontroller to disconnect all the battery cells in the plurality of battery cells from the load in order to prevent further discharging of the respective battery cell in which the non-zero minimum voltage has been reached to a cell-ruining voltage below the non-zero minimum voltage;
wherein said cell balancing means is configured to establish the shunt in response to a signal from said slave sensing means when the respective slave sensing means has measured a maximum voltage across the respective battery cell that has reached the maximum charging state; and
wherein the charging of the battery cells is controlled by the central controlling microcontroller.
2. The modular battery management system of claim 1 , wherein the central controlling microcontroller is operatively connected to each of the plurality of battery monitoring modules via a common data bus.
3. The modular battery management system of claim 1 , wherein the central controlling microcontroller is operatively connected to each of the plurality of battery monitoring modules via a wireless connection.