Inter-module voltage balance correcting circuit of a power storage system

• US 8,917,059 B2
• Filed: 08/05/2009
• Issued: 12/23/2014
• Est. Priority Date: 08/06/2008
• Status: Active Grant

• Current Assignee: FDK Corporation (Fujitsu Limited)
• Original Assignee: FDK Corporation (Fujitsu Limited)
• Inventors: Nakao, Fumiaki
• Primary Examiner(s): Dunn, Drew A
• Assistant Examiner(s): GRANT, ROBERT J
• Application Number:
  US13/003,662
• Publication Number:
  US 20110109270A1
• Time in Patent Office: 1,966 Days
• Field of Search: 320/118
• US Class Current: 320/118
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/482 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 2010/4271 Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Provided is an inter-module voltage balance correcting circuit of a power storage system including a plurality of storage modules connected in series, each of the storage modules including a plurality of storage cells connected in series. The inter-module voltage balance correcting circuit includes a resistance voltage dividing circuit (R1-R2) that equally divides a series voltage across a first storage module and a second storage module connected in series; and a pair of transistors that are turned ON/OFF complementarily based on a voltage (Vp1-Vp2) appearing between an intermediate connecting point (p2) between the storage modules M1, M2 in series and a voltage dividing point p1 of the resistance voltage dividing circuit, and a bypass discharge resistive element is selectively connected to modules by turning ON/OFF the complementary transistors.

Claims

1. An inter-module voltage balance correcting circuit of a power storage system including a plurality of storage modules connected in series, each of the storage modules including a plurality of storage cells connected in series, the inter-module voltage balance correcting circuit comprising:

a resistance voltage dividing circuit that equally divides a series voltage across a first storage module and a second storage module connected in series;

a pair of transistors that are turned ON/OFF in a complementary manner based on a voltage that appears between an intermediate connecting point between the first and second storage modules and a voltage dividing point of the resistance voltage dividing circuit, the pair of transistors having commonly connected bases and commonly connected emitters; and

a resistive element whose one end is connected to the commonly connected bases and whose other end is connected to the commonly connected emitters, the one end of the resistive element being further connected to the voltage dividing point, the other end of the resistive element being further connected to the intermediate connecting point,

one of the pair of transistors being turned ON in a case where a dividing voltage that appears at the voltage dividing point becomes higher than an intermediate voltage that appears at the intermediate connecting point and causing a bypass discharge resistive element to be connected to a storage module situated at a positive side of the series-connected storage modules,

the other of the pair of transistors being turned ON in a case where the dividing voltage becomes lower than the intermediate voltage and causing a bypass discharge resistive element to be connected to a storage module situated at a negative side of the series-connected storage modules.

2. The inter-module voltage balance correcting circuit according to claim 1,

wherein, in a case where three or more storage modules are connected in series, a correction circuit unit including the resistance voltage dividing circuit and the transistors is provided for every two storage modules situated next to each other in an order of connection in the series.

3. The inter-module voltage balance correcting circuit according to claim 2,

further comprising an electric current passage correction resistive element that equalizes a current passage condition of an electric current flowing through the resistance voltage dividing circuit of each of the correction circuit units.

4. The inter-module voltage balance correcting circuit according to claim 1,

wherein each of the pair of transistors is provided with a transistor added thereto that forms a multi-stage direct-coupled amplification circuit.

5. The inter-module voltage balance correcting circuit according to claim 4,

wherein the added transistor is a Darlington-connected bipolar transistor.

6. The inter-module voltage balance correcting circuit according to claim 1,

wherein each of the storage modules is provided with an overcharge protection circuit that monitors voltages of the plurality of storage cells connected in series individually and, in a case there is a cell having a high voltage, connects the cell to a bypass discharge resistive element, and

wherein, by being turned ON, the pair of transistors causes all of the bypass discharge resistive elements in the protection circuit to be connected at once to the cells in the modules.