Safe battery energy management systems, battery management system nodes, and methods
A battery stack includes a plurality of battery management system (BMS) nodes and a controller. Each BMS node includes a battery, an isolation switch configured to selectably isolate the battery of the BMS node from the batteries of the other BMS nodes, and a bypass switch configured to selectably provide a path for electrical current flowing through the battery stack to bypass the battery of the BMS node. The batteries of the BMS nodes are electrically coupled in series. The controller is configured to control the isolation switch and the bypass switch of each BMS node such that the battery of each BMS node can be individually connected to and disconnected from an electrical power source/sink.
1. A first battery management system (BMS) node with reverse voltage failure mode protection, comprising:
a battery including a positive terminal and a negative terminal;
a direct-current to direct-current (DC-DC) converter including an output port configured to be electrically coupled in series with at least a second BMS node;
a first isolation switch electrically coupling the battery to the DC-DC converter and configured to selectively connect and disconnect the battery from the DC-DC converter; and
a second isolation switch configured to prevent flow of electric current in event of a short circuit between the first BMS node and the second BMS node.
2. The first BMS node of claim 1 , further including a controller configured to open each of the first and second isolation switches in response to a signal to electrically isolate the battery.
3. The first BMS node of claim 1 , wherein the first isolation switch is electrically coupled between the positive terminal of the battery and the DC-DC converter, and the second isolation switch is electrically coupled between the negative terminal of the battery and the DC-DC converter.
4. The first BMS node of claim 1 , wherein:
the first isolation switch includes a first transistor including a first body diode, an anode of the first body diode being connected to the DC-DC converter, and a cathode of the first body diode being connected to the positive terminal of the battery; and
the second isolation switch includes a second transistor including a second body diode, an anode of the second body diode being connected to the negative terminal of the battery, and a cathode of the second body diode being connected to the DC-DC converter.
5. The first BMS node of claim 1 , wherein the second isolation switch is electrically coupled to the output port of the DC-DC converter.
6. The first BMS node of claim 1 , wherein:
the first isolation switch includes a first transistor electrically coupled between the positive terminal of the battery and the DC-DC converter, the first transistor including a first body diode, an anode of the first body diode being electrically coupled to the DC-DC converter, and a cathode of the first body diode being electrically coupled to the battery; and
the second isolation switch includes a second transistor including a second body diode, a cathode of the second body diode being connected to a positive terminal of the output port of the DC-DC converter.
7. The first BMS node of claim 1 , wherein:
the first isolation switch includes a first transistor electrically coupled between the negative terminal of the battery and the DC-DC converter, the first transistor including a first body diode, an anode of the first body diode being electrically coupled to the negative terminal of the battery, and a cathode of the first body diode being electrically coupled to the DC-DC converter; and
the second isolation switch comprises a second transistor including a second body diode, a cathode of the second body diode being connected to a positive terminal of the output port of the DC-DC converter.
8. The first BMS node of claim 1 , wherein the DC-DC converter is capable of operating as one or more of a boost converter and a buck converter.
9. A battery management system (BMS) stack, comprising:
a first BMS node, including a first battery with a positive terminal and a negative terminal, a first direct-current to direct-current (DC-DC) converter, and a first isolation switch electrically coupling one of the positive and negative terminals of the first battery to the first DC-DC converter; and
a second BMS node, including a second battery with a positive terminal and a negative terminal, a second DC-DC converter, a second isolation switch electrically coupling one of the positive and negative terminals of the second battery to the second DC-DC converter, and a third isolation switch configured to prevent flow of electric current in event of a short circuit between the first and second battery management system nodes.
10. The BMS stack of claim 9 , wherein the first isolation switch is electrically coupled between the positive terminal of the first battery and the first DC-DC converter, the second isolation switch is electrically coupled between the positive terminal of the second battery and the second DC-DC converter, and the third isolation switch is electrically coupled between the negative terminal of the second battery and the second DC-DC converter.
11. The BMS stack of claim 9 , wherein the third isolation switch includes a transistor including a body diode, an anode of the body diode being connected to the negative terminal of the second battery, and a cathode of the body diode being connected to the second DC-DC converter.
12. The BMS stack of claim 9 , wherein the third isolation switch is electrically coupled to an output port of the second DC-DC converter.
13. The BMS stack of claim 12 , wherein the third isolation switch includes a transistor including a body diode, a cathode of the body diode being connected to a positive terminal of the output port of the second DC-DC converter.
14. The BMS stack of claim 9 , wherein each of the first DC-DC converter and the second DC-DC converter is capable of operating as one or more of a boost converter and a buck converter.
15. A battery management system (BMS) stack, comprising:
a first BMS node, including:
a first switch and a second switch electrically coupled in series,
a first battery,
a first inductor electrically coupled between a positive terminal of the first battery and an electrical node joining the first switch and the second switch, and
a third switch electrically coupled in series with the first battery and the first inductor; and
a second BMS node, including:
a fourth switch and a fifth switch electrically coupled in series with the first switch and the second switch,
a second battery,
a second inductor electrically coupled between a positive terminal of the second battery and an electrical node joining the fourth switch and the fifth switch,
a sixth switch electrically coupled in series with the second battery and the second inductor, and
an isolation switch configured to prevent flow of electric current in event of a short circuit between the first battery and a negative electrical node of the second BMS node.
16. The BMS stack of claim 15 , wherein the isolation switch is electrically coupled in series with the third switch.
17. The BMS stack of claim 16 , wherein the isolation switch comprises a transistor including a body diode, the transistor being arranged such that the body diode has an orientation preventing an electric current flowing into a negative terminal of the first battery from flowing through the body diode.
18. The BMS stack of claim 15 , wherein the isolation switch is electrically coupled between the second switch and the fourth switch.
19. The BMS stack of claim 18 , wherein the isolation switch comprises a transistor including a body diode, the transistor being arranged such that the body diode has an orientation preventing an electric current flowing from the first BMS node to the second BMS node from flowing through the body diode.
20. The BMS stack of claim 15 , wherein:
the first switch, the second switch, and the first inductor form at least part of a first direct-current to direct-current (DC-DC) converter; and
the fourth switch, the fifth switch, and the second inductor form at least part of a second DC-DC converter.