JP6271227B2 - Balance correction device and power storage device - Google Patents

Description

  The present invention relates to a balance correction device and a power storage device for equalizing voltages between power storage cells or between power storage modules composed of a plurality of power storage cells connected in series in an assembled battery composed of a plurality of power storage cells connected in series.

  In an assembled battery in which a plurality of power storage cells are connected in series, it is necessary to suppress variations in voltage (electromotive force) between the power storage cells in order to prevent a reduction in discharge capacity and a reduction in life. In particular, as in a power storage device used in an electric vehicle or the like, an assembled battery composed of a large number of power storage cells is required to strictly suppress voltage variation between the power storage cells.

  As a mechanism for equalizing the voltage between the storage cells, for example, in Patent Document 1, one end of an inductor L is connected to a connection point of secondary batteries B1 and B2 connected in series, and switching elements S1 and S2 are connected. By alternately turning on and off, the first mode in which current flows through a first closed circuit formed by connecting the other end of the inductor L to the other end of the battery B1, and the other end of the inductor L to the other end of the battery B2. A so-called converter that equalizes the voltages of the secondary batteries B1 and B2 by executing a switching operation for alternately repeating a second mode in which a current is passed through a second closed circuit formed by connection for a short period of time. A method of balance correction is disclosed.

  Here, in the balance correction circuit described in Patent Document 1, the inductor L is charged and discharged regardless of whether or not the secondary batteries B1 and B2 are in a balanced state, and the switching operation is always performed. For this reason, there exists a subject that there are many useless power losses by impedance components, such as resistance parasitic to inductor L and switching element S1, S2.

  Therefore, in order to reduce this power loss, for example, Patent Document 2 includes a rest period td in which both switching elements S1 and S2 are turned off when the voltage difference Vx between the two storage cells is reduced. It is described.

JP 2001-185229 A JP 2008-017655 A

  FIG. 7 shows an example of a converter type balance correction circuit 7. As shown in the figure, the balance correction circuit 7 includes an inductor L, two switching elements S 1 and S 2, and a control circuit 20.

  In the figure, one end of the inductor L is connected to an intermediate connection point N between the first power storage cell B1 and the second power storage cell B2 that move back and forth in the order of series connection. The first switching element S1 is interposed between the other end of the inductor L and one series connection end of the two storage cells B1 and B2 to form a switching circuit.

  Similarly, the second switching element S2 is interposed between the other end of the inductor L and the other series connection end of the two storage cells B1 and B2 to form a switching circuit. The control circuit 20 generates square wave pulse signals φ1 and φ2 to turn on and off the switching elements S1 and S2 in a complementary manner.

  FIG. 8 shows the relationship between the on / off states of the switching elements S1 and S2 and the current flowing through the inductor L (hereinafter referred to as inductor current iL).

  FIG. 8A shows the waveforms of the control signals φ1 and φ2 generated by the control circuit 20 during the period when the on / off control of the switching elements S1 and S2 is performed. During the period, the control circuit 20 generates, for example, control signals φ1 and φ2 composed of square waves that are complementarily turned on and off at the same period as shown in FIG.

  8B to 8D are waveforms of the current iL flowing through the inductor L during the period when the on / off control of the switching elements S1 and S2 is performed. Of these, FIG. 8B shows the waveform of the current iL flowing through the inductor L when the voltage E1 of the storage cell B1 is higher than the voltage E2 of the storage cell B2, and FIG. 8C shows the voltage of the storage cell B1. FIG. 8D shows the waveform of the current iL flowing through the inductor L when E1 is lower than the voltage E2 of the storage cell B2, and FIG. 8D shows that the voltage E1 of the storage cell B1 and the voltage E2 of the storage cell B2 are equal ( This is a waveform of the current iL flowing through the inductor L in the case of substantially equal).

  As shown in FIG. 8B, when the voltage of the storage cell B1 is higher than the voltage of the storage cell B2 (B1> B2), during the period when the switching element S1 is on and the switching element S2 is off, The current iL flows through a positive path of the cell B1, a switching element S1, an inductor L, an intermediate connection point N, and a negative path of the storage cell B1 (hereinafter referred to as a first path). That is, during this period, current iL flows mainly in the direction of the solid line arrow shown in FIG.

  Thereafter, when the switching element S1 is turned off and the switching element S2 is turned on, the energy stored in the inductor L passes through the path of the inductor L → the positive electrode of the storage cell B2 → the negative electrode of the storage cell B2 → the switching element S2 → the inductor L. The battery cell B2 is charged by this.

  As shown in FIG. 8C, when the voltage of the power storage cell B1 is lower than the voltage of the power storage cell B2 (B1 <B2), the power storage is mainly performed while the switching element S1 is off and the switching element S2 is on. A current iL flows through a path (hereinafter, referred to as a second path) of the positive electrode of the cell B2, the inductor L, the switching element S2, and the negative electrode of the storage cell B2. That is, during this period, current iL flows mainly in the direction of the broken line arrow shown in FIG.

  Thereafter, when the switching element S2 is turned off and the switching element S1 is turned on, the energy stored in the inductor L passes through the path of the inductor L → the switching element S1 → the positive electrode of the storage cell B1 → the negative electrode of the storage cell B1 → the inductor L. The battery cell B1 is charged by this.

  As shown in FIG. 8D, when the voltage of the storage cell B1 and the voltage of the storage cell B2 are equal (B1 = B2), the storage cells B1 and B2 are connected with the on / off control of the switching elements S1 and S2. The balance of energy exchanged in (1) and (2) is balanced, and the voltage between the storage cells B1 and B2 is kept uniform.

  As described above, when there is a voltage difference between the storage cells B1 and B2, the current iL alternately flows through the first path and the second path, thereby transferring energy between the storage cell B1 and the storage cell B2. As a result, both voltages are equalized to ensure cell balance.

  In the balance correction circuit 7 described above, the inductor iL flows in both directions regardless of the voltage difference between the storage cells B1 and B2, and the inductor L always repeats charging and discharging. Therefore, power is wasted due to the switching elements S1 and S2 and the resistance of the wiring. Furthermore, since the two switching elements S1 and S2 require a predetermined driving power to turn them on and off, it is desirable from the viewpoint of reducing power consumption that the switching elements S1 and S2 should not be operated unnecessarily. .

  The present invention has been made in view of such a background, and an object of the present invention is to provide a balance correction device and a power storage device that can efficiently equalize voltages between power storage cells while suppressing power consumption. It is said.

  In order to achieve the above object, one of the present inventions is an aggregate battery composed of a plurality of power storage cells connected in series, between power storage cells or between power storage modules composed of a plurality of power storage cells connected in series. A balance correction device for equalizing voltage, the inductor having one end connected to a connection point between the first power storage module and the second power storage module connected in series, and the first power storage module A first switching element connected in series with the inductor between the positive and negative terminals of the second storage element; a second switching element connected in series with the inductor between the positive and negative terminals of the second power storage module; and the first Voltage difference detection for detecting a voltage difference Vx = VB1-VB2 which is a difference between the voltage VB1 of the power storage module and the voltage VB2 of the second power storage module And controlling on / off control of the first switching element or the second switching element to control the supply of current to each of the power storage modules, thereby transferring power between the power storage modules via the inductor. A balance correction unit having a switching control unit that generates and equalizes the voltage between the power storage modules, and the switching control unit has a voltage VB1 of the first power storage module of the second power storage module. When the voltage is higher than the voltage VB2 (Vx> 0), only the first switching element is turned on / off, and when the voltage VB1 of the first power storage module is lower than the voltage VB2 of the second power storage module (Vx < In (0), only the second switching element is on / off controlled.

  Another aspect of the present invention is the balance correction device, wherein the first unidirectional element D1 is connected so as to be in a reverse direction with respect to the voltage of the first power storage module, and the second It is assumed that the second unidirectional element D2 is connected so as to be in the reverse direction with respect to the voltage of the power storage module.

  Another aspect of the present invention is the balance correction apparatus, wherein the first unidirectional element D1 is a parasitic diode of the first switching element, and the second unidirectional element D2 is And a parasitic diode of the second switching element.

  Another aspect of the present invention is the balance correction apparatus, wherein the switching control unit is configured such that when the absolute value of the voltage difference Vx exceeds a preset threshold value Vt1 (> 0), In addition, both the second switching element and the second switching element are complementarily controlled on and off.

  Another aspect of the present invention is the balance correction device, wherein the switching control unit is configured to switch the first switching element when the voltage difference Vx exceeds a preset threshold value Vt2 (> 0). Only in cycle T1 (= on period tw1 + off period td1), and when the voltage difference Vx is less than −Vt2, only the second switching element is cycled in T1 (= on period tw1 + off period td1). On / off control is performed.

  Another aspect of the present invention is the balance correction apparatus, wherein the switching control unit is configured such that the voltage difference Vx is equal to or less than Vt2 and exceeds a preset threshold value Vt3 (Vt2> Vt3> 0). Only the first switching element is turned on / off in a cycle T2 (> T1) (= on period tw2 (<tw1) + off period td2 (> td1)), and the voltage difference Vx is less than −Vt3 and greater than or equal to −Vt2. In some cases, only the second switching element is controlled to be turned on / off in a cycle T2 (> T1) (= on period tw2 (<tw1) + off period td2 (> td1)).

  Another aspect of the present invention is the balance correction apparatus, wherein the period T2 is n times the period T1 (n is a natural number of 2 or more).

  Another aspect of the present invention is the balance correction apparatus, wherein the switching control unit is configured to perform the first switching when the voltage difference Vx exceeds a preset threshold value Vt1 (> Vt2). Only the element is controlled to be turned on / off in a cycle T1 (= on period tw1 + off period td1), and when the voltage difference Vx is less than −Vt1 (<−Vt2), only the second switching element is cycled T1 (= on The on / off control is performed in the period tw1 + off period td1).

  Another aspect of the present invention is the balance correction apparatus, wherein the switching control unit is configured such that when the absolute value of the voltage difference Vx is less than a preset threshold value Vt3 (> 0), The on / off control of the second switching element is stopped.

  Another aspect of the present invention is the balance correction apparatus, comprising a voltage dividing circuit that divides a series voltage of the first power storage module and the second power storage module, wherein the voltage difference detection unit includes the voltage difference detection unit, Detecting the voltage difference Vx based on a difference between a voltage obtained by equally dividing the series voltage by a voltage dividing circuit and a voltage at a series connection point of the first power storage module and the second power storage module. And

  Another aspect of the present invention is the balance correction apparatus, comprising a plurality of the balance correction units, wherein the first power storage module of one of the balance correction units is the one of the other balance correction unit. It is connected so that it may become the said electrical storage module same as a said 2nd electrical storage module.

  Another aspect of the present invention is a power storage device including the plurality of power storage cells and the balance correction device.

  In addition, the subject which this application discloses, and its solution method are clarified by the column of the form for inventing, and drawing.

  ADVANTAGE OF THE INVENTION According to this invention, the voltage between electrical storage cells can be equalized efficiently, suppressing power consumption.

2 is a diagram illustrating a configuration of a balance correction circuit 1. FIG. It is a waveform of the ON / OFF state of the switching elements S1 and S2 and the inductor current iL of the balance correction circuit 1 of the first embodiment. It is a waveform of the ON / OFF state of the switching elements S1 and S2 and the inductor current iL of the balance correction circuit 1 of the first embodiment. FIG. 6 shows waveforms of the on / off states of the switching elements S1 and S2 of the balance correction circuit 1 and the inductor current iL, which are shown as modifications of the first embodiment. It is a waveform of the ON / OFF state of the switching elements S1 and S2 and the inductor current iL of the balance correction circuit 1 of the second embodiment. It is a waveform of the ON / OFF state of the switching elements S1 and S2 and the inductor current iL of the balance correction circuit 1 of the second embodiment. It is a waveform of the ON / OFF state of the switching elements S1 and S2 and the inductor current iL of the balance correction circuit 1 of the second embodiment. It is a waveform of the on-off state of the switching elements S1 and S2 and the inductor current iL shown as a modification of the second embodiment. It is an example of the balance correction circuit 6 corresponding to the equalization of the voltage of three or more electrical storage cells. It is an example of the balance correction circuit 7 of a converter system. It is a figure which shows the relationship between the on-off state of switching element S, S2 and the inductor current iL.

  Hereinafter, embodiments of the present invention will be described. In the following description, the same or similar parts may be denoted by the same reference numerals and redundant description may be omitted. Further, the same constituent elements may be collectively referred to by omitting the suffix part of the reference (for example, the control circuits 10A, 10B, and 10C are collectively referred to as the control circuit 10).

First embodiment

[Basic configuration of balance correction circuit]
FIG. 1 shows a converter type balance correction circuit 1 (balance correction apparatus). The balance correction circuit 1 includes, for example, a power storage device (an electric vehicle, a hybrid vehicle, an electric motorcycle, a railway vehicle, a lift, a power storage device for system linkage, a personal computer, a notebook computer) that uses an assembled battery composed of a plurality of power storage cells connected in series. (Book type computer, mobile phone, smartphone, PDA device, etc.). The power storage cell is, for example, a lithium ion secondary battery, a lithium ion polymer secondary battery, or the like, but may be another type of power storage element such as an electric double layer capacitor.

  When manufacturing quality and the degree of deterioration differ between the storage cells that make up the assembled battery, battery characteristics (battery capacity, discharge voltage characteristics) may vary between storage cells. As a result, the voltage between the storage cells may vary during charging and discharging. In order to prevent this variation from occurring, the balance correction circuit 1 operates so as to equalize the voltage between the storage cells or between the storage modules composed of a plurality of storage cells connected in series (cell balance is ensured). To do.

  As shown in the figure, an assembled battery 3 is constituted by power storage cells B1 and B2 connected in series. The positive and negative terminals 31 and 32 of the assembled battery 3 include, for example, a current supply source (for example, a charger, a regenerative circuit, etc.) that supplies a charging current to the assembled battery 3 and a load that functions using the electromotive force of the assembled battery 3. (For example, a motor, an electronic circuit, an electrical product, etc.) are connected.

  One end of the inductor L is connected to a line connecting the negative electrode of the storage cell B1 and the positive electrode of the storage cell B2 (a line including the series connection point Nm of the storage cells B1 and B2). A switching element S1 is provided on the line connecting the other end of the inductor L and the positive electrode of the storage cell B1. A switching element S2 is provided on a line connecting the other end of the inductor L and the negative electrode of the storage cell B2.

  The switching elements S1 and S2 are configured using MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors). The switching elements S1 and S2 are on / off controlled via a gate driver (not shown) by control signals φ1 and φ2 input from a control signal generation circuit 12 (switching control unit) described later. The switching elements S1 and S2 can also be configured using bipolar transistors.

  Unidirectional elements D1 and D2 (diodes and the like) are connected in parallel to the switching elements S1 and S2, respectively. The unidirectional element D1 is connected in the opposite direction to the voltage (inter-terminal voltage) of the storage cell B1 (in the forward direction with respect to the current flowing from the inductor L into the storage cell B1). The unidirectional element D2 is connected in the opposite direction to the voltage (inter-terminal voltage) of the storage cell B2 (in the forward direction with respect to the current flowing from the inductor L into the storage cell B2).

  If the inductor current iL remains during the period when both of the switching elements S1 and S2 are off, the residual inductor current iL can continue to flow through the unidirectional elements D1 and D2. As a result, the energy stored in the inductor L can be used without waste. Further, it is possible to suppress the generation of a surge voltage that occurs when the inductor current iL is cut off.

  Note that a parasitic diode (also referred to as an internal diode) is normally formed in parallel between the source and drain of the MOSFET, but if this is used as the unidirectional elements D1 and D2, the circuit configuration is simplified. Thus, the number of elements and the manufacturing cost can be reduced.

  The control circuit 10 includes a control signal generation circuit 12, resistance elements R1 and R2, and a differential amplifier circuit 13.

  The resistance values of the resistance elements R1 and R2 are set to be equal, and these are divided voltages that equally divide the series voltage of the two storage cells B1 and B2 (the voltage between the positive and negative terminals 31 and 32 of the assembled battery 3). The circuit is configured.

  The differential amplifier circuit 13 includes a voltage difference Vx (= Vm−Vn = storage cell) between the voltage Vm appearing at the intermediate connection point Nm of the storage cells B1 and B2 and the divided voltage Vn appearing at the connection point Nn of the resistance elements R1 and R2. The voltage VB1 of the B1-the voltage VB2 of the storage cell B2) is linearly amplified with a predetermined gain and input to the control circuit 10.

  The control signal generation circuit 12 generates two-phase control signals φ1 and φ2 to be supplied to each of the gate drivers. In the present embodiment, the control signals φ1 and φ2 are two-phase (high level, low level) square waves with a predetermined duty ratio (for example, PWM pulse (PWM: Pulse Width Modulation)). The control signal generation circuit 12 determines the duty widths of the control signals φ1 and φ2, the presence / absence of generation of the control signals φ1 and φ2, and the like according to the voltage difference Vx input from the differential amplifier circuit 13. The signal generation circuit 12 includes, for example, a microcomputer including an arithmetic device (CPU (Central Processing Unit), MPU (Micro Processing Unit), etc.) and a storage device (RAM (Random Access Memory), ROM (Read Only Memory), etc.). It is comprised using.

  In addition to the above configuration, the storage cells B1, B2 are used for the purpose of reducing noise caused by the on / off operation of the switching element and alleviating voltage changes generated in the storage cells B1, B2 due to the on / off operation of the switching element. Capacitance elements may be provided between the positive and negative terminals, between the positive and negative terminals 31 and 32 of the assembled battery 3, and the like.

Subsequently, the operation of the balance correction circuit 1 of the first embodiment will be described.
2A and 2B show the ON / OFF states of the switching elements S1 and S2 of the balance correction circuit 1 and the waveform of the inductor current iL.

  FIG. 2A (a) shows the switching elements S1, S2 when the voltage VB1 of the storage cell B1 is “much higher” than the voltage VB2 of the storage cell B2 (Vx> Vt1) (Vt1 is a preset positive threshold). It is a waveform of an on-off state and inductor current iL. 2A (b) shows the switching element S1, when the voltage VB1 of the storage cell B1 is “higher” than the voltage VB2 of the storage cell B2 (Vt1 ≧ Vx> Vt2) (Vt2 is a preset positive threshold). It is a waveform of the ON / OFF state of S2 and the inductor current iL. FIG. 2A (c) shows the on / off state of the switching elements S1 and S2 and the inductor when the voltage VB1 of the storage cell B1 and the voltage VB2 of the storage cell B2 are “approximately equal (equal)” (Vt2 ≧ Vx ≧ −Vt2). It is a waveform of current iL. 2B (d) shows the on / off states of the switching elements S1 and S2 and the inductor current iL when the voltage VB1 of the storage cell B1 is “lower” than the voltage VB2 of the storage cell B2 (−Vt2> Vx ≧ −Vt1). It is a waveform. 2B (e) shows the waveforms of the on / off states of the switching elements S1 and S2 and the inductor current iL when the voltage VB1 of the storage cell B1 is “much lower” (−Vt1> Vx) than the voltage VB2 of the storage cell B2. is there.

  2A (a) and 2 (b), the voltage VB1 of the storage cell B1 is “much higher” (Vx> Vt1) or “higher” (Vt1 ≧ Vx> Vt2) than the voltage VB2 of the storage cell B2. ), The control signal generation circuit 12 performs on / off control of only the switching element S1 at a constant period T1 (= on period tw1 + off period td1). As a result, the inductor L is charged by the inductor current iL flowing from the storage cell B1 (this inductor current iL flows in the direction of the solid line arrow in FIG. 1), and the inductor current iL based on the energy charged in the inductor L ( The inductor current iL flows in the direction of the solid line arrow in FIG. 1) and the discharging period of the inductor L that charges the storage cell B2 (at this time, the inductor current iL flows into the storage cell B2 via the unidirectional element D2). Occur alternately. At this time, the control signal generation circuit 12 stops the on / off control for the switching element S2, so that the inductor current iL does not flow in the direction of the broken line arrow in FIG. 1 (energy is transferred from the storage cell B2 to the storage cell B1). do not do). Further, since the on / off control of the switching element S2 is stopped, the loss associated with the on / off control of the switching element S2 does not occur.

  Note that the control signal generation circuit 12 has a period T1, ON, depending on, for example, the purpose of use of the balance correction circuit 1, the properties of the elements constituting the balance correction circuit 1, the performance required for the balance correction circuit 1, and the like. The period tw1 and the off period td1 are set to appropriate values. 2A (a) and 2 (b), the control signal generation circuit 12 sets the on period tw1 and the off period td1 according to the voltage difference Vx. That is, as shown in FIG. 2A (a), when the voltage VB1 of the storage cell B1 is “substantially higher” than the voltage VB2 of the storage cell B2 (Vx> Vt1), the ON period tw1 becomes large (for example, the ON period tw1 = When the voltage VB1 of the storage cell B1 is “higher” (Vt1 ≧ Vx> Vt2) than the voltage VB2 of the storage cell B2, as shown in FIG. 2A (b), the on period tw1 is reduced. (For example, the on period tw1 <the off period td1). Thereby, when the voltage VB1 of the storage cell B1 is “much higher” than the voltage VB2 of the storage cell B2 (Vx> Vt1), the amount of charge (electric energy) from the storage cell B1 to the storage cell B2 performed via the inductor L1 ) Increases, and the voltage between the storage cells B1 and B2 can be quickly equalized. Further, when the voltage VB1 of the power storage cell B1 is “higher” than the voltage VB2 of the power storage cell B2 (Vt1 ≧ Vx> Vt2), it is possible to avoid an excessive operation that shortens the ON period tw1 and increases power loss.

  In this way, the balance correction circuit 1 is large when the voltage VB1 of the storage cell B1 is “much higher” (Vx> Vt1) or “higher” (Vt1 ≧ Vx> Vt2) than the voltage VB2 of the storage cell B2. It is possible to efficiently equalize the voltages of a plurality of power storage cells connected in series without causing power loss.

  As shown in FIG. 2A (c), when the voltage VB1 of the storage cell B1 and the voltage VB2 of the storage cell B2 are “almost equal (equal)” (Vt2 ≧ Vx ≧ −Vt2), the control signal generation circuit 12 On / off control is stopped for both the first and second switching S1 and S2. For this reason, the loss accompanying on-off control of switching element S1, S2 does not generate | occur | produce.

  As shown in FIGS. 2B (d) and 2 (e), the voltage VB1 of the storage cell B1 is “lower” (−Vt2> Vx ≧ −Vt1) or “substantially lower” (−Vt1>) than the voltage VB2 of the storage cell B2. Vx), the control signal generation circuit 12 performs on / off control of only the switching element S2 at a constant period T1 (= on period tw1 + off period td1). As a result, the inductor L is charged by the inductor current iL flowing from the storage cell B2 (the inductor current iL flows in the direction of the broken line arrow in FIG. 1), and the inductor current iL based on the energy charged in the inductor L ( When this inductor current iL flows in the direction of the broken line arrow in FIG. 1, the discharging period of the inductor L that charges the storage cell B2 (at this time, the inductor current iL flows into the storage cell B1 via the unidirectional element D1). Occur alternately. At this time, since the control signal generation circuit 12 stops the on / off control for the switching element S1, the inductor current iL does not flow in the direction of the solid line arrow in FIG. 1 (energy is transferred from the storage cell B1 to the storage cell B2). do not do). Further, since the on / off control of the switching element S1 is stopped, the loss associated with the on / off control of the switching element S1 does not occur.

  Note that the control signal generation circuit 12 has a period T1, ON, depending on, for example, the purpose of use of the balance correction circuit 1, the properties of the elements constituting the balance correction circuit 1, the performance required for the balance correction circuit 1, and the like. The period tw1 and the off period td1 are set to appropriate values. 2B and 2E, the control signal generation circuit 12 sets an on period tw1 and an off period td1 according to the voltage difference Vx. That is, as shown in FIG. 2B (d), when the voltage VB1 of the storage cell B1 is “lower” than the voltage VB2 of the storage cell B2 (−Vt2> Vx ≧ −Vt1), the ON period tw1 becomes small (eg, ON Period tw1 <off period td1), and as shown in FIG. 2B (e), when the voltage VB1 of the storage cell B1 is “substantially lower” (−Vt1> Vx) than the voltage VB2 of the storage cell B2, the on period tw1 (For example, ON period tw1 = OFF period td1). Thus, when the voltage VB1 of the storage cell B1 is “lower” than the voltage VB2 of the storage cell B2 (−Vt2> Vx ≧ −Vt1), the on-period tw1 is shortened to avoid an excessive operation that increases power loss. Can do. Further, when the voltage VB1 of the storage cell B1 is “much lower” than the voltage VB2 of the storage cell B2 (−Vt1> Vx), the amount of charge (electric energy) from the storage cell B2 to the storage cell B1 performed via the inductor L1 Increases, and the voltage between the storage cells B1 and B2 can be quickly equalized.

  Thus, in the balance correction circuit 1, the voltage VB1 of the storage cell B1 is “lower” (−Vt2> Vx ≧ −Vt1) than the voltage VB2 of the storage cell B2, or the voltage VB1 of the storage cell B1 is stored in the storage cell B2. When the voltage VB2 is “substantially lower” (−Vt1> Vx), it is possible to efficiently equalize the voltages of a plurality of storage cells connected in series without large power loss.

  When the absolute value of the voltage difference Vx is large (for example, when Vx> Vt1 or −Vt1> Vx), the control signal generation circuit 12 performs on / off control of both of the two switching elements S1 and S2 in a complementary manner. You may do it. The waveform in that case is shown in FIG. FIG. 3A shows a case where Vx> Vt1, and FIG. 3E shows a case where −Vt1> Vx. By doing so, the energy charged in the inductor L can be efficiently supplied from the high-voltage storage cell to the low-voltage storage cell, and the voltages of the storage cells B1 and B2 can be quickly equalized. .

  2A (a) and FIG. 2B (e), or FIG. 2A (b) and FIG. 2B (d), the on period tw1 (or the off period td1) does not necessarily have to be set to the same value. May be set.

Second embodiment

  The configuration of the balance correction circuit 1 of the second embodiment is basically the same as that of the first embodiment. In the second embodiment, the voltage of the storage cells B1 and B2 is efficiently equalized by changing the cycle T1 (= on period tw + off period td) according to the voltage difference Vx.

  4A to 4C show the on / off states of the switching elements S1 and S2 and the waveform of the inductor current iL of the balance correction circuit 1 of the second embodiment.

  FIG. 4A (a) shows the switching elements S1, S2 when the voltage VB1 of the storage cell B1 is “much higher” than the voltage VB2 of the storage cell B2 (Vx> Vt1) (Vt1 is a preset positive threshold). It is a waveform of an on-off state and inductor current iL. FIG. 4A (b) shows switching elements S1, S2 when the voltage VB1 of the storage cell B1 is “higher” (Vt1 ≧ Vx> Vt2) (Vt2 is a preset positive threshold) than the voltage VB2 of the storage cell B2. This is a waveform of the ON / OFF state and the inductor current iL. FIG. 4A (c) shows the switching element S1, when the voltage VB1 of the storage cell B1 is “slightly higher” than the voltage VB2 of the storage cell B2 (Vt2 ≧ Vx> Vt3) (Vt3 is a preset positive threshold). It is a waveform of the ON / OFF state of S2 and the inductor current iL. FIG. 4B (d) shows the ON / OFF state of the switching elements S1 and S2 and the inductor current when the voltage VB1 of the storage cell B1 and the voltage VB2 of the storage cell B2 are “almost equal (equal)” (Vt3 ≧ Vx ≧ −Vt3). It is a waveform of iL. FIG. 4B (e) shows the ON / OFF states of the switching elements S1 and S2 and the inductor current iL when the voltage VB1 of the storage cell B1 is “slightly lower” (−Vt3> Vx ≧ −Vt2) than the voltage VB2 of the storage cell B2. It is a waveform. FIG. 4B (f) shows the on / off states of the switching elements S1 and S2 and the inductor current iL when the voltage VB1 of the storage cell B1 is “slightly lower” (−Vt2> Vx ≧ −Vt1) than the voltage VB2 of the storage cell B2. It is a waveform. FIG. 4C (g) shows the waveforms of the on / off states of the switching elements S1 and S2 and the inductor current iL when the voltage VB1 of the storage cell B1 is “much lower” (−Vt1> Vx) than the voltage VB2 of the storage cell B2. .

  As shown in FIGS. 4A and 4B, the voltage VB1 of the storage cell B1 is “much higher” (Vx> Vt1) or “higher” (Vt1 ≧ Vx> Vt2) than the voltage VB2 of the storage cell B2. ), The control signal generation circuit 12 performs on / off control of only the switching element S1 at a constant period T1 (= on period tw1 + off period td1). The operation of the balance correction circuit 1 at this time is the same as in the case of FIGS. 2A (a) and (b).

  As shown in FIG. 4A (c), when the voltage VB1 of the storage cell B1 is “slightly higher” than the voltage VB2 of the storage cell B2 (Vt2 ≧ Vx> Vt3), the control signal generation circuit 12 turns on only the switching element S1. On / off control is performed at a cycle T2 (> T1) (= on period tw2 (<tw1) + off period td2 (> td1)).

  Thus, when the voltage VB1 of the storage cell B1 is “slightly higher” than the voltage VB2 of the storage cell B2 (Vt2 ≧ Vx> Vt3), the control signal generation circuit 12 sets only the switching element S1 to a cycle T2 longer than the cycle T1. (> T1) (= ON period tw2 (<tw1) + OFF period td2 (> td1)), and the off period td2 is lengthened, thereby reducing the power loss caused by turning on and off the switching element S1. be able to. Even in this case, the charging / discharging current iL of the inductor L necessary for eliminating the “slightly high” voltage difference can be ensured due to the presence of the ON period of the switching element S1, so the voltage of the switching elements S1 and S2 is It is possible to equalize efficiently.

  In FIG. 4A (c), the switching element S1 is controlled to be turned on / off at a cycle T2 (= on tw2 (<tw1) + off period td2 (> td1)) n times the cycle T1 (n is an integer of 2 or more). You may do it. Thus, by setting the cycle T2 to an integral multiple of the cycle T1, the circuit configuration can be simplified. For example, a circuit that thins out (skips) the ON period tw1 from the waveform shown in FIG. 4A (b) is configured. (Or such an algorithm) makes it possible to easily realize the control shown in FIG. 4A (c).

  As shown in FIG. 4B (d), when the voltage VB1 of the storage cell B1 and the voltage VB2 of the storage cell B2 are “almost equal (equal)” (Vt3 ≧ Vx ≧ −Vt3), the control signal generation circuit 12 performs switching. On / off control is stopped for both S1 and S2, and the off state is continued. For this reason, the loss accompanying on-off control of switching element S1, S2 does not generate | occur | produce. Even if the inductor current iL remains during the period when both the switches S1 and S2 are off, the residual inductor current iL can continue to flow through the unidirectional elements D1 and D2. For this reason, the energy stored in the inductor L can be used without waste, and the generation of a surge voltage that occurs when the inductor current iL is interrupted can be suppressed.

  As shown in FIG. 4B (e), when the voltage VB1 of the energy storage cell B1 is “slightly lower” (−Vt3> Vx ≧ −Vt2) than the voltage VB2 of the energy storage cell B2, the control signal generation circuit 12 includes the switching element S2. Only on / off control is performed in cycle T2 (> T1) (= on period tw2 (<tw1) + off period td2 (> td1)).

  As described above, when the voltage VB1 of the storage cell B1 is “slightly lower” (−Vt3 ≧ Vx> −Vt2) than the voltage VB2 of the storage cell B2, the control signal generation circuit 12 sets only the switching element S2 longer than the cycle T1. On / off control is performed in a cycle T2 (> T1) (= on period tw2 (<tw1) + off period td2 (> td1)), and the off period td2 is lengthened. Therefore, power loss due to turning on and off the switching element S1 is reduced. be able to. Even in this case, the presence of the ON period of the switching element S2 can secure the inductor current iL necessary to eliminate the “slightly low” voltage difference, and thus the voltage of the switching element S1 can be equalized efficiently. be able to.

  In FIG. 4B (e), the switching element S2 is on / off controlled at a period T2 (= on tw2 (<tw1) + off period td2 (> td1)) n times the period T1 (n is an integer of 2 or more). You may do it. Thus, the circuit configuration can be simplified by setting the cycle T2 to be an integral multiple of the cycle T1. For example, by configuring a circuit that thins out (skips) the on period tw1 from the waveform shown in FIG. 4B (f) (or such an algorithm), the control shown in FIG. 4B (e) can be easily performed. Can be realized.

  As shown in FIGS. 4B (f) and 4C (g), the voltage VB1 of the storage cell B1 is “lower” than the voltage VB2 of the storage cell B2 (−Vt2> Vx ≧ −Vt1) or “pretty low”. When (−Vt1> Vx), the control signal generation circuit 12 performs on / off control of only the switching element S2 at a constant cycle T1 (= on period tw1 + off period td1). Note that the specific operation of the balance correction circuit 1 at this time is the same as in the case of FIGS. 2B (d) and 2 (e).

  As described above, the control signal generation circuit 12 performs switching when the voltage VB1 of the storage cell B1 is “slightly higher” than the voltage VB2 of the storage cell B2 (Vt2 ≧ Vx> Vt3) (FIG. 4A (c)). Only the element S1 is controlled to be turned on / off in a cycle T2 (> T1) (= on period tw2 (<tw1) + off period td2 (> td1)), and the off period td2 is lengthened. For this reason, the loss accompanying the on / off control of the switching element S2 does not occur, and the power loss caused by turning on / off the switching element S1 can be reduced. Further, when the voltage VB1 of the storage cell B1 is “slightly lower” (−Vt3> Vx ≧ −Vt2) (FIG. 4B (e)), the control signal generation circuit 12 controls only the switching element S2. On / off control is performed in a cycle T2 (> T1) (= on period tw2 (<tw1) + off period td2 (> td1)), and the off period td2 is lengthened. For this reason, the loss accompanying the on / off control of the switching element S1 does not occur, and the power loss caused by turning on / off the switching element S2 can be reduced. As described above, the balance correction circuit 1 of the present embodiment can efficiently equalize the voltages of a plurality of storage cells connected in series without causing a large power loss regardless of the value of the voltage difference Vx. it can.

  When the absolute value of the voltage difference Vx is large (for example, when Vx> Vt1 or −Vt1> Vx), the control signal generation circuit 12 performs complementary on / off control of both the two switching elements S1 and S2. It may be. The waveform in that case is shown in FIG. FIG. 5A shows the case where Vx> Vt1, and FIG. 5G shows the case where −Vt1> Vx. By doing so, the energy charged in the inductor L can be efficiently supplied from the high voltage storage cell to the low voltage storage cell, and the voltages of the storage cells B1 and B2 can be quickly equalized. it can.

  4A (a) and FIG. 4C (g), and FIG. 4A (b) and FIG. 4B (f), the on period tw1 (or the off period td1) does not necessarily have to be set to the same value. It may be set. 4A (c) and 4B (e), the on period tw2 (or off period td2) is not necessarily set to the same value, and may be set to a different value.

  By the way, description of embodiment described above is for making an understanding of this invention easy, and does not limit this invention. It goes without saying that the present invention can be changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof.

  For example, in the balance correction circuit 1 described above, the on periods tw1, tw2 and the off periods td1, td2 may be set according to the inductor current iL instead of the voltage difference Vx between the storage cells B1, B2. . In this case, the inductor current iL may be obtained by a current sensor provided in series with the inductor L, or is obtained by detecting the inductor voltage vL with a voltage sensor provided in parallel with the inductor L and integrating it. You may do it.

  Moreover, the structure of the balance correction circuit 1 demonstrated above can be extended when there are three or more storage cells. FIG. 6 is an example of a balance correction circuit corresponding to equalization of voltages of three or more power storage cells. In the figure, only the main part of the balance correction circuit is shown. The balance correction circuit 6 includes a plurality of balance correction units 61 having the same configuration as the balance correction circuit 1 described above.

  As shown in the figure, in this balance correction circuit 6, one of the storage cells of one balance correction unit 61 is one of the storage cells of the other balance correction unit 61 provided one after the other. They are wired so that they are in common. The control circuit 10A complementarily turns on and off the switching elements S1 and S2 to equalize the voltage of the storage cell B1 and the voltage of the storage cell B2, and the control circuit 10B complementarily turns on and off the switching elements S3 and S4. Thus, the voltage of the storage cell B2 and the voltage of the storage cell B3 are equalized. As a result, the voltage of the storage cell B2 is equalized with the voltages of both of the two storage cells B1, B3, and the voltages of the three storage cells B1, B2, B3 are equalized. Similarly, the voltages of the other power storage cells B4, B5, B6... Are also equalized, and the voltages are equalized among all the power storage cells targeted for equalization by the balance correction circuit 6. .

  The balance correction circuit of the present invention may be provided separately from the storage cell, or may be integrated with the storage cell to form a battery pack or the like.

  DESCRIPTION OF SYMBOLS 1 Balance correction circuit, 10 Control circuit, 12 Control signal generation circuit, 13 Differential amplifier circuit, B1, B2 Storage cell, S1, S2 switching element, D1, D2 Unidirectional element

Claims (9)

In a collective battery composed of a plurality of power storage cells connected in series, a balance correction device for equalizing voltage between the power storage cells or between power storage modules composed of a plurality of power storage cells connected in series,
An inductor having one end connected to a connection point between the first power storage module and the second power storage module connected in series;
A first switching element connected in series with the inductor between the positive and negative terminals of the first power storage module;
A second switching element connected in series with the inductor between the positive and negative terminals of the second power storage module;
A voltage difference detection unit that detects a voltage difference Vx = VB1−VB2 that is a difference between the voltage VB1 of the first power storage module and the voltage VB2 of the second power storage module;
By controlling on / off of the first switching element or the second switching element, the supply of current to each of the power storage modules is controlled, thereby causing power to be transferred between the power storage modules via the inductor. Switching controller for equalizing the voltage between the storage modules,
A balance correction unit having
The switching controller is
When the voltage difference Vx exceeds a preset threshold value Vt2 (> 0), only the first switching element is turned on / off in a cycle T1 (= on period tw1 + off period td1),
When the voltage difference Vx is less than −Vt2, only the second switching element is on / off controlled in a cycle T1 (= on period tw1 + off period td1),
When the voltage difference Vx is equal to or less than Vt2 and exceeds a preset threshold value Vt3 (Vt2>Vt3> 0), only the first switching element has a period T2 (> T1) (= on period tw2 (<tw1) + On-off control in the off-period td2 (> td1)),
When the voltage difference Vx is less than −Vt3 and greater than or equal to −Vt2, only the second switching element is turned on / off in a cycle T2 (> T1) (= on period tw2 (<tw1) + off period td2 (> td1)). Balance correction device to control . The balance correction apparatus according to claim 1,
The first unidirectional element D1 is connected so as to be in the reverse direction with respect to the voltage of the first power storage module, and the second one is set in the reverse direction with respect to the voltage of the second power storage module. The balance correction apparatus to which the directional element D2 is connected. The balance correction apparatus according to claim 2,
The first unidirectional element D1 is a parasitic diode of the first switching element, and the second unidirectional element D2 is a parasitic diode of the second switching element.   The balance correction apparatus according to claim 1,
  The period T2 is n times the period T1 (n is a natural number of 2 or more).
  Balance correction device. The balance correction apparatus according to any one of claims 1 to 4 ,
When the absolute value of the voltage difference Vx exceeds a preset threshold value Vt1 (> Vt2 ), the switching control unit complementarily turns on and off both the first and second switching elements. Correction device. The balance correction device according to any one of claims 1 to 5 ,
When the absolute value of the voltage difference Vx is less than the preset threshold value Vt3 (> 0), the switching control unit stops on / off control of the first and second switching elements. The balance correction apparatus according to any one of claims 1 to 6 ,
A voltage dividing circuit for dividing a series voltage of the first power storage module and the second power storage module;
The voltage difference detection unit is based on a difference between a voltage obtained by equally dividing the series voltage by the voltage dividing circuit and a voltage at a series connection point of the first power storage module and the second power storage module. A balance correction device for detecting the voltage difference Vx. The balance correction device according to any one of claims 1 to 7 ,
A plurality of the balance correction units;
The balance correction device, wherein the first power storage module of one of the balance correction units is wired to be the same power storage module as the second power storage module of the other one of the balance correction units. A power storage device comprising the plurality of power storage cells and the balance correction device according to any one of claims 1 to 8 .

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