Sensor arrangement and a method for monitoring a storage system

A redundant electric energy storage system, comprising:

• a plurality of storage units for electric energy that are connected in series between a reference voltage node and a first or a second output terminal to provide electric energy to at least one consumer at the first or at the second output terminal, and
• a sensor arrangement comprising:
• a plurality of sensor units configured to determine charging levels of the storage units by measuring at least one of the following quantities:
• (i) one or more voltages between reference voltage node and a node between adjacent storage units,
• (ii) one or more voltage drops over at least a subset of the storage units,
• (iii) electric currents though the first and/or through second output terminal, or
• (iv) temperatures of the storage units;
• wherein:
• the vehicle storage system further comprises at least one charge balancing unit configured to provide a current path between the first output terminal and the second output terminal, the current path being parallel to at least one of the storage units;
• the sensor units comprise at least one pair of current sensors arranged in series between the first or the second output terminal and the storage units, and the balancing unit couples to a node between the two current sensors to enable current measurements through the first or second output terminal and through the charge balancing unit.

A method of monitoring a state of a storage system for electric energy, the method comprising:

• providing a storage system having a plurality of serially connected storage units, at least a first and a second output terminal, and a charge balancing unit for providing a current path between the first and the second output terminal;
• and
• measuring at least one of the following quantities:
• (i) one or more voltages between a reference voltage node and a node between adjacent storage units of the serially connected storage units,
• (ii) one or more voltage drops over at least a subset of the storage units,
• (iii) electric currents though the first and/or the second output terminal, or
• (iv) temperatures of the storage units;
• wherein:
• the vehicle storage system further comprises at least one charge balancing unit configured to provide a current path between the first output terminal and the second output terminal, the current path being parallel to at least one of the storage units;
• the sensor units comprise at least one pair of current sensors arranged in series between the first or the second output terminal and the storage units, and the balancing unit couples to a node between the two current sensors to enable current measurements through the first or second output terminal and through the charge balancing unit.