JP6143819B2 - Constant voltage circuit and power supply system - Google Patents

Description

  The present invention relates to a constant voltage circuit and a power supply system.

  In recent years, power storage devices applied to power storage systems have become widespread. Examples of the electricity storage device include a lithium ion battery and a lithium ion capacitor. The power storage device includes a plurality of power storage cells connected in series. The power storage device has a protection circuit that monitors the temperature and voltage of the power storage device and protects the power storage device by avoiding overcharge and overdischarge.

  For example, an additional circuit such as a protection circuit for the power storage device is driven by power supplied from the power storage cell of the power storage device. The additional circuit is driven by power of a constant voltage. Therefore, the power supplied from the storage cell to the additional circuit is controlled to be a constant voltage by a constant voltage circuit such as a regulator.

JP 2007-305475 A

  Here, in the above technique, a constant voltage circuit such as a regulator is required to correspond to voltages from the highest level to the lowest level of a plurality of power storage cells connected in series in the power storage device. For example, as illustrated in FIG. 2, the power supply system 1A according to the related art includes a power storage module 200 including four 16V storage cell groups 210 to 240 connected in series, and a constant voltage circuit 10A. The power storage module 200 is an example of a power storage device. The constant voltage circuit 10A includes a regulator 11A. The regulator 11 </ b> A is supplied with a regulator input from the highest voltage VTOP of the power storage module 200. That is, in the example shown in FIG. 2, the regulator 11A needs to correspond to a voltage of 16V × 4 = 64V.

  In recent years, the number of storage cells in series in an storage device has increased. For this reason, the voltage from the highest level to the lowest level of the plurality of power storage cells connected in series in the power storage device has become higher. Therefore, the regulator is required to be able to handle an input voltage range up to a high voltage. However, a regulator that can handle high voltages consumes a large amount of power and is expensive.

  On the other hand, there is a method of supplying a regulator input from a voltage intermediate between a plurality of storage cells connected in series. However, this method has a problem in that the power consumption of each storage cell connected in series is different, so that the voltage of each storage cell is not uniform and the voltage balance is lost.

  In view of the above-described problems, an example of the disclosed technique is to reduce power consumption and stabilize power supply with an inexpensive configuration while maintaining the voltage balance of each storage cell in the storage device.

  An example of the constant voltage circuit and the power supply system of the disclosed technology is dropped by the source follower circuit and the source follower circuit that drop the highest voltage of the plurality of storage cells connected in series to an intermediate voltage between the plurality of storage cells. And a regulator circuit for stabilizing the power supply using the intermediate voltage as an input voltage.

  According to an example of the disclosed technology, for example, in a power storage device, it is possible to reduce power consumption and stabilize power supply with an inexpensive configuration while maintaining the voltage balance of each power storage cell.

FIG. 1A is a diagram illustrating an example of a power supply system according to the embodiment. FIG. 1B is a diagram illustrating an example of details of the power supply system according to the embodiment. FIG. 2 is a diagram illustrating an example of a power supply system according to the related art.

[Embodiment]
Hereinafter, embodiments of a constant voltage circuit and a power supply system according to an example of the disclosed technique will be described with reference to the drawings. In the following description, the same reference numerals are given to the same components, and the description will be omitted in later cases. The following embodiments are merely examples, and do not limit the disclosed technology.

(Power supply system according to the embodiment)
FIG. 1A is a diagram illustrating an example of a power supply system according to the embodiment. The power supply system 1 according to the embodiment includes a power storage module 200 including four power storage cell groups 210 to 240 connected in series, and a power storage device protection circuit 100. Each power storage cell group 210 to 240 is configured by connecting, for example, four power storage cells in series, and each voltage is 4V × 4 = 16V.

  Note that the power storage device protection circuit 100 may be provided on a control board of the power storage module 200 (not shown). The control board of the power storage module 200 is disposed in the vicinity of the power storage module 200. The power storage device protection circuit 100 further includes a constant voltage circuit 10, a first circuit 20, and a second circuit 30.

  The storage device protection circuit 100 receives the input IN1 from the VTOP voltage of 16V × 4 = 64V of the uppermost storage cell group 240 of the storage module 200, and the voltage of 16V × 1 = 16V between the storage cell groups 210 and 220 The input IN2 is input. The constant voltage circuit 10 performs power source stabilization such as constant voltage or smoothing of DC current by the input IN2. Then, the constant voltage circuit 10 outputs an output OUT subjected to power supply stabilization such as constant voltage or smoothing of a direct current to the first circuit 20.

  The first circuit 20 is a circuit driven by a stabilized power source such as an IC (Integrated Circuit). The input IN1 is also input to the second circuit 30. Here, the second circuit 30 is a circuit driven by a power source that does not need to be stabilized. The storage cell group 210, the constant voltage circuit 10, the first circuit 20, and the second circuit 30 are grounded.

(Details of power supply system according to the embodiment)
FIG. 1B is a diagram illustrating an example of details of the power supply system according to the embodiment. In FIG. 1B, the configuration of the power storage device protection circuit 100 in the power supply system 1 according to the embodiment shows only the constant voltage circuit 10, and the others are omitted. In addition, the numbers and characteristic values of the components shown in the embodiments are merely examples.

  The constant voltage circuit 10 includes a regulator 11, capacitors 12 to 13 having a capacitance of, for example, 0.1 μF, and an N-channel field effect transistor 14. One end of the capacitor 12 is connected to the source S of the N-channel field effect transistor 14, and the other end is grounded. One end of the capacitor 13 is connected to the output end of the regulator 11, and the other end is grounded.

  The regulator 11 is an example of a regulator circuit. The regulator 11 has an input terminal connected to the source S of the N-channel field effect transistor 14 and an output terminal connected to the first circuit 20 (see FIG. 1A) and the capacitor 13. The regulator 11 is activated when an EN signal is input via an EN (ENable) signal line, and is deactivated when the EN signal is interrupted.

  The N-channel field effect transistor 14 is an example of a source follower circuit. The drain D of the N-channel field effect transistor 14 is connected to the highest voltage VTOP of the power storage module 200. Further, the gate G of the N-channel field effect transistor 14 is connected between the storage cell groups 210 and 220 that are intermediate voltages of the storage module 200. With this connection, the voltage of the gate G of the N-channel field effect transistor 14 becomes 16V × 1 = 16V. The voltage at the drain D of the N-channel field effect transistor 14 is 16V × 4 = 64V. In addition, the voltage at the source S of the N-channel field effect transistor 14 becomes (the voltage between the storage cell groups 210 and 220-the voltage between the gate and the source necessary for flowing current).

  The voltage at the source S of the N-channel field effect transistor 14 is, for example, about (16V-0.6V). Since the input voltage to the regulator 11 only needs to allow the voltage of the source S of the N-channel field effect transistor 14, the regulator 11 allows input of a voltage higher than the voltage of the source S of the N-channel field effect transistor 14, for example, 20V. Anything is acceptable.

  As described above, the regulator 11 receives the voltage from the source S of the N-channel field effect transistor 14 in which the gate G is connected between the storage cell groups 210 and 220, thereby causing the regulator 11 to exceed the highest voltage of the storage module 200. With a low voltage, power supply stabilization such as constant voltage or smoothing of direct current can be performed. The gate G of the N-channel field effect transistor 14 is supplied with 16V, which is an intermediate voltage of the power storage module 200, but almost no current flows through the gate G. Therefore, the storage cell groups 210 to 240 of the storage module 200 and the storage cells included in the storage cell groups 210 to 240 are held to have the same voltage balance, and the currents output from the storage cells are substantially the same. Become.

  The input IN2 is not limited to the voltage between the storage cell groups 210 and 220, but may be the voltage between the storage cell groups 220 and 230 and the voltage between the storage cell groups 230 and 240. Even if the input IN2 is a voltage other than that between the storage cell groups 210 and 220, the regulator 11 can operate at a voltage lower than the highest voltage 64V of the storage module 200.

  The N-channel field effect transistor 14 is an enhancement type, but it may be a depletion type N-channel field effect transistor instead of the enhancement type.

(Effect by embodiment)
In the embodiment, the highest voltage of the power storage module 200 is divided by the N-channel field effect transistor 14, and the voltage is dropped to an input voltage that can be allowed by the regulator 11 and input to the regulator 11. Therefore, a regulator that cannot accept a high voltage can be adapted to the high voltage power storage module 200 by inputting the voltage after appropriately dropping the voltage.

  In general, a circuit (for example, a CMU (Cell Monitoring Unit), a BMU (Battery Management Unit), or the like) used in the power supply system 1 that is a power storage device operates with power supplied from the power storage module 200. Therefore, if the power consumption of the circuit is large, a large amount of power charged in the power storage device is consumed by itself. If the power storage device is a capacitor, the capacity is small, and thus the variation in SOC (State Of Charge) due to self-consumption of the circuit increases. For example, in the case of a power storage device having a capacity of 1 Ah, if the circuit consumes 100 μA of current, the SOC will be reduced by about 10% in about 42 days even when charging and discharging are not performed.

  Furthermore, for example, when applying a regulator to a power storage device exceeding 80 V, a regulator with a current consumption of about 20 μA must be selected. An inexpensive regulator can be used.

  Thus, the embodiment can reduce the cost by using a relatively inexpensive regulator for the power storage device, and can reduce the amount of current consumed by the regulator in the power storage device. The embodiments can also be widely applied to power supplies for various devices.

  Each part of the constant voltage circuit according to the above embodiment may be appropriately integrated or distributed depending on the circuit design. In addition, a balance correction circuit configured by appropriately combining, substituting, and omitting each part of the constant voltage circuit according to the above embodiment is also included in the constant voltage circuit according to the disclosed technique.

DESCRIPTION OF SYMBOLS 1 Power supply system 10 Constant voltage circuit 11 Regulator 12, 13 Capacitor 14 N channel field effect transistor 20 1st circuit 30 2nd circuit 100 Power storage device protection circuit 200 Power storage module 210-240 Power storage cell group

Claims (4)

A source follower circuit for dropping the highest voltage of a plurality of storage cells connected in series to an intermediate voltage between the plurality of storage cells;
And a regulator circuit for stabilizing a power supply using the intermediate voltage dropped by the source follower circuit as an input voltage. The source follower circuit includes an N-channel field effect transistor having a drain connected to the highest voltage, a gate connected to the intermediate voltage, and dropping the highest voltage to the intermediate voltage,
2. The constant voltage circuit according to claim 1, wherein the regulator circuit includes a regulator having an input terminal connected to a source of the N-channel field effect transistor and performing power supply stabilization using the intermediate voltage as an input voltage. . The constant input voltage of the regulator is equal to or higher than a voltage obtained by subtracting a voltage between a gate and a source of the N-channel field effect transistor from the intermediate voltage and lower than the highest voltage. Voltage circuit. The plurality of storage cells;
A power supply system comprising: the constant voltage circuit according to claim 1.

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