Parallel electricity-storage system and control method thereof

A control method of a parallel electricity-storage system that includes battery banks formed of one battery cell or a plurality of battery cells that are serially connected, and a charge/discharge circuit that charges respective battery banks via a DC bus or supplies discharged power from the respective battery banks received via the DC bus to a load device, wherein the parallel electricity-storage system has a configuration in which

• number of the DC buses in the parallel electricity-storage system is plural,
• number of the charge/discharge circuits is same as that of the DC buses,
• number of the battery banks is larger than the number of the DC buses, and
• a switch provided for each of the battery banks and serially connected to the battery bank to switch connection between the battery bank and each of the DC buses so that one of the DC buses is selected,
• the control method comprising:
• a first step of
• stopping an operation of a first charge/discharge circuit being a charge/discharge circuit as a connection source electrically connected with a first battery bank targeted to be switched, and
• increasing an operating current of at least one of the charge/discharge circuits other than the first charge/discharge circuit so that an output of the system is maintained;
• a second step of switching, by a controller, a first switch connected with the first battery bank to a charge/discharge circuit other than the first charge/discharge circuit so as to be electrically connected;
• and
• a third step of returning the operating current of the charge/discharge circuits including the first charge/discharge circuit back to that in a state before having been switched.

A control method of a parallel electricity-storage system that includes battery banks formed of one battery cell or a plurality of battery cells that are connected serially, and a charge/discharge circuit that charges respective battery banks via a DC bus or supplies discharged power from the respective battery banks received via the DC bus to a load device, wherein the parallel electricity-storage system has a configuration in which

• number of the DC buses in the parallel electricity-storage system is plural,
• number of the charge/discharge circuits is same as that of the DC buses,
• number of the battery banks is provided larger than the number of the DC buses, and
• a switch provided for each of the battery banks and serially connected to the battery bank to switch connection between the battery bank and each of the DC buses so that one of the DC buses is selected,
• the control method comprises:
• a first step of
• increasing an output of a first charge/discharge circuit being a charge/discharge circuit as a connection source electrically connected with a first battery bank targeted to be switched, and
• decreasing a SOC of a battery bank electrically connected to a first DC bus connected with the first charge/discharge circuit;
• a second step of stopping an operation of the first charge/discharge circuit and increasing an operating current of at least one of the charge/discharge circuits other than the first charge/discharge circuit so as to maintain an output of the system;
• a third step of switching, by a controller, a first switch connected with the first battery bank to a neutral position;
• a fourth step of
• waiting until a voltage at a time of shutdown of a second DC bus being a charge/discharge circuit as a switching destination connected with the second charge/discharge circuit becomes equal to a voltage of the first battery bank, and thereafter,
• increasing an output of the first charge/discharge circuit, and stopping an operation of the second charge/discharge circuit;
• a fifth step of switching the first switch to the second bus side so as to input the first battery bank to the second bus;
• and
• a sixth step of increasing an output of the second charge/discharge circuit, and decreasing the output of the first charge/discharge circuit.