JP2018160966A - Balancer, power supply device, and balancing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform balancing at low cost and with little loss.SOLUTION: A balancer 110 comprises a transformer 40. The balancer 110 is a flyback converter type. The transformer 40 includes one or more primary coils 21, 22 that are connected to the first battery pack 120, and a plurality of secondary coils 51, 52, 53, 54 that are connected to a plurality of cells b1, b2, b3, b4 constituting a second battery pack 120 which is separated from the first battery pack 120.SELECTED DRAWING: Figure 5

Description

  The present invention relates to battery pack balancing.

  The assembled battery is used in, for example, an electric vehicle (EV), a plug-in hybrid vehicle (PHEV), and a home energy management system (HEMS). The assembled battery is configured by connecting a plurality of cells. In an assembled battery, the remaining amount of a plurality of cells may vary. Variations in remaining amount between cells are corrected by a balancer.

  The battery pack balancer is roughly classified into a passive balancer and an active balancer. The passive balancer takes out power from a cell with a large remaining amount and consumes the power as heat in the load, thereby correcting the variation in the remaining amount. A passive balancer is low in cost with a small number of circuit elements, but has a large loss. The active balancer takes power from a cell with a large remaining amount and returns the power to a cell with a small remaining amount. An active balancer has less loss than a passive balancer, but has a large number of circuit elements and high cost.

Japanese Patent Application Laid-Open No. 2014-7885 JP 2013-162661 A

  In view of the characteristics of the passive balancer and the active balance, there is a need for a balancing technique with low cost and low loss. The inventors automatically transfer the second assembled battery from the first assembled battery to the second assembled battery via the flyback converter without active control on the secondary side. Found that it can be balanced and charged.

  In the embodiment, the balancer uses the flyback converter system to transfer the power of the first assembled battery to the plurality of secondary coils connected to the plurality of cells constituting the second assembled battery by the flyback converter method. Transport to. Since each current flowing from the transformer to the plurality of cells of the second assembled battery increases as the cell voltage decreases, the second assembled battery is balance-charged.

  In the embodiment, the balancing method uses the transformer having a plurality of secondary coils connected to the plurality of cells constituting the second assembled battery, and uses the flyback converter method to store the energy accumulated from the primary side. It includes the balance charging of the plurality of cells by discharging to the plurality of secondary coils connected to the plurality of cells. Since each current flowing to the plurality of cells increases as the cell voltage decreases, the second assembled battery is balance-charged.

  Although patent document 1 and patent document 2 are disclosing the balancer, neither literature is disclosing automatically carrying out the balance charge of the 2nd assembled battery.

  Patent Document 1 only discloses that energy released from one assembled battery is returned to the assembled battery itself via a transformer, and is different from the first assembled battery and the first assembled battery. The second assembled battery is not disclosed. Further, Patent Document 1 discloses a plurality of secondary coils, but the energy stored from the primary side is connected to one cell having the lowest charging rate by active control using a switch. It only discloses releasing from one secondary coil, and the stored energy is released from a plurality of secondary coils connected to a plurality of cells, and the second assembled battery is automatically balanced and charged. It is not disclosed to do.

  Patent Document 2 discloses a balancer that conveys the energy of an assembled battery to another assembled battery, but discloses a plurality of secondary coils connected to a plurality of cells that constitute an assembled battery that is an energy carrying destination. Therefore, it does not disclose automatic and balanced charging of the assembled battery at the energy transfer destination.

It is a lineblock diagram of an electric vehicle provided with a power unit concerning an embodiment. It is a block diagram of the electric vehicle provided with the power supply device which concerns on a comparative example. It is a block diagram of the power supply device which concerns on embodiment. It is a block diagram of the power supply device which concerns on embodiment It is operation | movement explanatory drawing of a flyback converter. It is operation | movement explanatory drawing of a flyback converter. It is an experimental circuit diagram. It is a gate waveform diagram. It is a primary side current waveform diagram. It is a secondary side current waveform diagram. It is a secondary side current waveform diagram. It is a secondary side current waveform diagram. It is an equivalent circuit of the experimental circuit It is a gate signal waveform diagram. It is a secondary side current waveform diagram. It is a figure which shows the increase in the electric charge amount of a cell. It is a gate signal waveform diagram. It is a secondary side current waveform diagram. It is a figure which shows the increase in the electric charge amount of a cell. It is a gate signal waveform diagram. It is a secondary side current waveform diagram. It is a figure which shows the increase in the electric charge amount of a cell. It is a gate signal waveform diagram. It is a secondary side current waveform diagram. It is a figure which shows the increase in the electric charge amount of a cell.

[1. Balancer, power supply, balancing method]

(1) The balancer according to the embodiment includes a transformer. The transformer has at least one primary coil and a plurality of secondary coils. At least one primary coil is connected to the first assembled battery. The plurality of secondary coils are connected to a plurality of cells constituting the second assembled battery. The second assembled battery is an assembled battery different from the first assembled battery. In the flyback method, when the first assembled battery is discharged, energy is accumulated in the primary coil in the transformer, and the energy accumulated in the transformer is released from the secondary coil. Since each current flowing from the plurality of secondary coils to the plurality of cells increases as the cell voltage decreases, the second assembled battery is balance-charged.

  The number of the plurality of secondary coils may be the same as or smaller than the number of the plurality of cells constituting the second assembled battery. For example, one secondary coil may correspond to one cell, or may correspond to m cells (m is an integer of 2 or more). That is, when the number of cells is n, the number of secondary coils may be n or n / m. When one secondary coil corresponds to one cell, each of the n cells constituting the second assembled battery is balance-charged. When one secondary coil corresponds to m or more cells, each of n / m cell sets is balance-charged using m cell sets as a unit of balancing.

(2) The at least one primary coil may be a plurality of primary coils connected to a plurality of cells constituting the first assembled battery.

  The number of the plurality of primary coils may be the same as the number of the plurality of cells constituting the first assembled battery, or may be small. For example, one primary coil may correspond to one cell, or may correspond to m cells (m is an integer of 2 or more). That is, when the number of cells is n, the number of primary coils may be n or n / m. When one primary coil corresponds to one cell, discharge is performed from each of n cells constituting the first assembled battery to the corresponding primary coil. When one primary coil corresponds to m or more cells, discharge is performed from each of n / m cell sets to the corresponding primary coil with m cell sets as a unit. Note that the number of cells in the first assembled battery may be different from the number of cells in the second assembled battery.

(3) The balancer may further include a plurality of switches that turn ON / OFF the flow of current from the plurality of cells constituting the first assembled battery to the plurality of primary coils. In this case, the plurality of cells constituting the first assembled battery can be selectively discharged.

(4) Based on the voltage of the some cell which comprises a primary side assembled battery, the controller which turns ON any one of a some switch and turns off another switch can be further provided. In this case, the controller can selectively discharge any one of the plurality of cells.

(5) The power supply device according to the embodiment includes a first assembled battery, a second assembled battery, and a balancer. The balancer has a plurality of primary coils through which current flows from the plurality of first cells constituting the first assembled battery, and a plurality of secondary coils through which current flows to the plurality of second cells constituting the second assembled battery. This is a flyback converter type balancer including a transformer.

(6) The first assembled battery is, for example, a battery for driving a car. The second assembled battery is, for example, an auxiliary battery for automobiles. The first assembled battery preferably has a higher voltage than the second assembled battery.

(7) The balancing method according to the embodiment uses the transformer having a plurality of secondary coils connected to the plurality of cells constituting the assembled battery, and uses the flyback converter method to store the energy accumulated from the primary side. And charging the plurality of cells in a balanced manner by discharging from the plurality of secondary coils connected to the plurality of cells.

(8) It is preferable that the energy accumulated from the primary side is obtained by balanced discharge of a plurality of cells constituting an assembled battery different from the assembled battery.

[2. Example of a power supply device equipped with a balancer]

  FIG. 1A shows the configuration of a hybrid vehicle. The hybrid vehicle includes a power supply device 100. 1A includes a main battery 120 and an auxiliary battery 130. The main battery 120 is a traveling battery that drives the traveling motor 150 and the like. The traveling battery 120 is, for example, a large assembled battery having an output voltage of 200 to 300V. In FIG. 1A, the traveling battery 120 supplies electric power to the motor 150 via the EPS converter 140. Auxiliary battery 130 drives an automotive auxiliary machine. The auxiliary battery 130 has a different output voltage from the traveling battery 120, and is a small assembled battery having an output voltage of 12V, for example.

  The power supply device 100 in FIG. 1A includes a balancer 110. The balancer 110 aligns the voltages of the cells that make up the assembled batteries 120 and 130. The balancer 110 discharges the assembled battery 120 to extract energy, conveys the energy to the assembled battery 130 different from the assembled battery 120, and charges the assembled battery 130. In the embodiment, the balancer 110 balances a plurality of cells constituting the assembled battery 120 when the assembled battery 120 is discharged. In addition, the balancer 110 balances a plurality of cells constituting the assembled battery 130 when the assembled battery 130 is charged.

  Since the balancer 110 in FIG. 1A reuses the electric power discharged from the assembled battery 120 in the assembled battery 130 different from the assembled battery 120, the power loss is less than that of the passive balancer.

  FIG. 1B shows a hybrid vehicle including a power supply device 200 according to a comparative example. Similar to the power supply device 100, the power supply device 200 includes a traveling battery 220 and an auxiliary battery 230. The batteries 220 and 230 include balancers 211 and 212, respectively. 1B includes a DC-DC converter 260 for charging auxiliary battery 230 with battery for traveling 220.

  When comparing FIG. 1A and FIG. 1B, in the power supply device 100 of FIG. 1A, the balancer 110 also functions as a DC-DC converter. Therefore, it is not necessary to include the DC-DC converter 260 as in FIG. Cost can be reduced. In addition, the balancer 110 in FIG. 1A balances both the batteries 120 and 130, so that it is not necessary to include the two balancers 211 and 212 as in FIG. 1B. From this viewpoint, the cost can be reduced.

  2 and 3 show an example of the balancer 110. In FIG. 2, a battery (first assembled battery) 120 connected to the primary side of the balancer 110 includes n cells a1 to an connected in series. A battery (second assembled battery) 130 connected to the secondary side of the balancer 110 includes n cells b1 to bn connected in series. In the two batteries 120 and 130, n may be different. In FIG. 3, the number n of cells in the battery 120 is two, and the number n of cells in the battery 130 is three.

  The balancer 110 includes a balancer circuit 110a. As shown in FIG. 3, the balancer circuit 110 a includes a transformer 40. The transformer 40 of FIG. 3 includes a plurality of primary coils 11 and 12 and a plurality of secondary coils 51, 52, and 53 provided on a magnetic core 41. In the transformer 40, the primary side and the secondary side have opposite polarities. As will be described later, the balancer circuit 110a operates in a flyback converter manner.

  In the embodiment, the number of turns of the plurality of primary coils a1 and a2 is the same. The number of turns of the plurality of secondary coils b1, b2, b3 is the same. The number of turns of the primary coils a1, a2 and the number of turns of the secondary coils b1, b2, b3 may be the same or different.

  The primary coil 11 has one end connected to the positive electrode side of the cell a1 and the other end connected to the negative electrode side of the cell a1 via the switch 21. When the switch 21 is turned on, a current flowing from the cell a1 to the primary coil 11 is generated. Note that current may flow from the plurality of cells connected in series or in parallel to the primary coil 11. When the switch 21 is turned off, the current is prevented from flowing through the primary coil 11, and the cell a1 is neither charged nor discharged.

  One end of the primary coil 12 is connected to the positive side of the cell a2, and the other end is connected to the negative side of the cell a2 via the switch 22. When the switch 22 is turned on, a current flowing from the cell a2 to the primary coil 12 is generated. The primary coil 12 may be supplied with current from a plurality of cells connected in series or in parallel. When the switch 22 is turned off, the current is prevented from flowing through the primary coil 12, and the cell a2 is neither charged nor discharged.

  The switches 21 and 22 are configured by MOSFETs, for example. Switch ON / OFF control is performed by the controller 110. The switches 21 and 22 may be provided between the positive electrodes of the cells a1 and a2 and the primary coils 11 and 12.

  The balancer 110 includes voltage measuring devices 31 and 32 that measure the voltages of the cells a1 and a2 of the battery 120. The voltage measuring devices 31 and 32 are connected in parallel to the cells a1 and a2. The voltages of the cells a1 and a2 measured by the voltage measuring devices 31 and 32 are given to the controller 110b.

  The controller 110b functions as a management system for the batteries 120 and 130. Specifically, the controller 110b controls ON / OFF of each of the plurality of switches 21 and 22 based on the voltages of the cells a1 and a2, and executes the balance discharge of the battery 120. For example, the controller 110b turns on a switch connected to the cell having the highest voltage in order to discharge the cell having the highest voltage among the cells a1 and a2. At this time, the switch connected to another cell is OFF. For example, if the voltage of the cell a1 is the highest, the controller 110 turns on the switch 21 and turns off the switch 22 to discharge the cell a1. As a result of such balanced discharge control, the voltages of the plurality of cells a1, a2 in the battery 120 are aligned.

  Since the plurality of primary coils 11 and 12 are provided in the common magnetic core 41 in the transformer 40, energy released from any of the plurality of cells a1 and a2 is intensively accumulated in the transformer 40. The

  One end of the secondary coil 51 is connected to the positive side of the cell b1 via the diode 61, and the other end is connected to the negative side of the cell b1. The diode 61 allows a current to flow from the secondary coil 51 to the cell b1, and prevents a current from flowing from the cell b1 to the secondary coil 51. When a current flowing to the positive electrode side of the cell b1 is generated in the secondary coil 51, the cell b1 is charged.

  The secondary coil 52 has one end connected to the positive side of the cell b2 via the diode 62 and the other end connected to the negative side of the cell b2. The diode 62 allows current to flow from the secondary coil 52 to the cell b2, and prevents current from flowing from the cell b2 to the secondary coil 52. When a current flowing to the positive electrode side of the cell b2 is generated in the secondary coil 52, the cell b2 is charged.

  The secondary coil 53 has one end connected to the positive side of the cell b3 via the diode 63 and the other end connected to the negative side of the cell b3. The diode 63 allows current to flow from the secondary coil 53 to the cell b3 and prevents current from flowing from the cell b3 to the secondary coil 53. When a current flowing to the positive electrode side of the cell b3 is generated in the secondary coil 53, the cell b3 is charged.

  The balancer circuit 110a includes capacitors 71, 72, and 73 connected in parallel to the cells b1, b2, and b3, respectively.

  In the circuit 110a of FIG. 3, a switchless circuit between the transformer 40 and the battery 130 does not include a switch (active element) controlled by the controller 110b. Since it is switchless, the plurality of secondary coils 51, 51, 53 are always connected to the plurality of cells b1, b2, b3.

  The balancer circuit 110a of FIG. 3 is a flyback converter type, and releases the magnetic energy accumulated in the transformer 40 from the primary side to the secondary side. The flyback converter has a simple structure, has a small number of elements, and can be easily reduced in cost.

  4A and 4B show the operation of a general flyback converter. This flyback converter has a switch 303 connected to a primary coil of a transformer 302 of reverse polarity. As shown in FIG. 4A, when the switch 303 is turned on, a current ia flows from the power supply 301 to the primary coil of the transformer 302, and magnetic energy is accumulated in the transformer 302. Thereafter, as shown in FIG. 4B, when the switch 303 is turned OFF, the current ib flows from the secondary coil of the transformer 302, and the magnetic energy accumulated in the transformer 302 is released. The flyback converter has no restriction on the voltage on the primary side and the secondary side. For this reason, the voltage of the battery connected to the primary side and the voltage of the battery connected to the secondary side may be different, which is advantageous for connection between the batteries 120 and 130 having different voltages.

  The balancer circuit 110a in FIG. 3 also basically operates in the same manner as the flyback converter in FIGS. 4A and 4B. That is, because of the balance discharge, when the switch 21 or the switch 22 is turned ON, a current flows from the cell a1 or the cell a2 to the primary coil 21 or the primary coil 22, and magnetic energy is accumulated in the transformer 40. When all the switches 21 and 22 are turned off by turning off the switch 21 or the switch 22 that has been turned on, a current flows through each of the secondary coils 51, 52, and 53 of the transformer 40, and the battery 130 is turned on. Each of the plurality of cells b1, b2b, b3 constituting the battery is charged.

  The currents flowing from the plurality of secondary coils 51, 52, 53 to the corresponding cells b1, b2, b3 are determined by the voltages of the cells b1, b2, b3. That is, the current flowing from the secondary coils 51, 52, and 53 to the cells b1, b2, and b3 increases as the cells b1, b2, and b3 have lower voltages. As a result, the cells b1, b2, and b3 having a low remaining voltage and a low voltage are charged more.

  Hereinafter, experimental results obtained by measuring the current flowing from the transformer 40 to each cell on the secondary side will be described. FIG. 5 shows an experimental circuit. In the experimental circuit, only one cell a1 was connected to the primary side of the transformer 40. At the time of primary-side balanced discharge, focusing on a certain point in time, discharge is performed from only one selected cell. Therefore, in order to confirm the current flowing in the secondary side, the primary-side cell is 1 Just enough.

  In the experimental circuit, four cells b1, b2, b3, b4 are connected to the secondary side of the transformer 40. In the experiment, nickel hydrogen batteries were used as the cells b1, b2, b3, and b4. The transformer 402 includes four secondary coils 51, 52, 53, and 54 corresponding to the four cells b1, b2, b3, and b4.

The cells b1, b2, b3, and b4 each have a nominal voltage of 3.8V. The initial voltage V _o1 of the cell b1 is 3.71V, the initial voltage V _o2 of the cell b2 is 3.57V, the initial voltage V _o3 of the cell b3 is 3.36V, and the initial voltage V _o4 of the cell b4 is 3.15V. (V _o1 > V _o2 > V _o3 > V _o4 ). The voltage Vil of the primary side cell a1 was set to 3.0V. The number of turns of the coils 11, 51, 52, 53, and 54 was all the same.

  Switching of the switch (MOSFET) 21 was performed with a pulse having a duty ratio of 0.45 and a frequency of 20 kHz. FIG. 6A shows a switching pulse applied to the gate of the MOSFET constituting the switch 21. The switch 21 is turned on when the pulse is at a high level, a current flows through the primary coil 11, and the switch 21 is turned off when the pulse is at a low level.

FIG. 6B shows a waveform of a current flowing through the primary coil 11 when the pulse of FIG. 6A is given to the switch 21. FIG. 6C shows a current i _cf4 flowing in the cell b4 when the pulse of FIG. 6A is applied to the switch 21. From FIG. 6B and FIG. 6C, it was confirmed that the circuit of FIG. 5 is operating in a flyback converter system.

In the circuit of FIG. 5, when the switch 21 is turned on, a current flows through the primary coil 11. At this time, a negative voltage v is applied to the secondary coils 51, 53, 54. Since the negative currents i _cn1 , i _cn2 , i _cn3 and i _cn4 are blocked by the diodes 61, 62, 63 and 64, a negative voltage v is applied to the secondary coils 51, 52, 53 and 54. Even so, no current flows on the secondary side (i _cn1 = i _cn2 = i _cn3 = i _cn4 = 0). As a result, magnetic energy is accumulated in the transformer 40.

7 and 8 show the currents i _cn1 , i _cn2 , i _cn3 , i from the secondary coils 51, 52, 53, 54 to the cells b1, b2, b3, b4 and the capacitors 71, 72, 73, ₇₄ , _respectively . _The electric current which flows into _cn4 is shown. In FIG. 7, the switch 21 is switched from ON to OFF at the time of 0 [μs] and 50 [μs].

When the switch 21 is switched from ON to OFF, the magnetic energy accumulated in the transformer 40 is released, and a current flows through all the secondary coils 51, 52, 53, and 54. When the switch 21 is switched from ON to OFF, the currents i _cn1 , i _cn2 , i _cn3 , and i _cn4 flowing through the secondary coils 51, 52, 53, and 54 increase from zero in a stepwise manner. For this reason, the voltage v applied to each secondary coil 51, 52, 53, 54 becomes very large. Since the voltage v at this time is sufficiently larger than the voltage difference between the cells b1, b2, b3, and b4, the currents i _cn1 , i _cn2 , i _cn3 , and i _cn4 all rise significantly.

The currents i _cn1 , i _cn2 , i _cn3 , and i _cn4 rise gradually and then gradually decrease. As shown in FIGS. 7 and 8, the slopes when the currents i _cn1 , i _cn2 , i _cn3 , and i _cn4 decrease decrease as the cell initial voltages V _o1 , V _o2 , V _o3 , and V _o4 ) increase. growing. Thereby, the current flowing through the cell having a low initial voltage increases, and the amount of charge increases as the cell has a lower initial voltage. As a result, the plurality of cells b1, b2, b3, b4 are balance-charged.

Hereinafter, the difference in slope of the currents i _cn1 , i _cn2 , i _cn3 , and i _cn4 will be described. When the currents i _cn1 , i _cn2 , i _cn3 and i _cn4 decrease, the voltage v of the secondary coils 51, 52, 53 and 54 and the currents i _cn1 , i _cn2 , i _cn3 and i _cn4 are excited by the transformer 40. It is determined by the inductance, leakage inductance, and voltages of the cells b1, b2, b3, and b4.

FIG. 9 shows an equivalent circuit when the currents i _cn1 , i _cn2 , i _cn3 , and i _cn4 decrease. In the equivalent circuit of FIG. 9, the number of cells and secondary coils is two for simplification of explanation. In FIG. 9, the exciting inductance L of the transformer 40 and the leakage inductance ls on the secondary side of the transformer 40 are shown. Here, the voltage of the cell b1 and _{V 1,} the current flowing through the cell b1 and _{i 1,} the voltage of the cell b2 and _{V 2,} the current flowing through the cell b2 and _{i 2.}

The circuit equation of the equivalent circuit of FIG. 9 is as follows.

Solving this circuit equation yields the following equations for currents i ₁ and i ₂ .

According to the above equation of the current _{i 1, i 2,} when _V 1> V _2,

Therefore, the slope of the current is decreased, the direction of current i ₁ flowing to the high cell b1 in voltage increases. Thus, larger current i ₂ flowing through the cell b2 low voltage, the charge amount of the cell b2 increases.

  Returning to FIG. 5, among the plurality of cells b1, b2, b3, and b4, a cell having a high initial voltage may reach full charge during charging. When there is a fully charged cell among the plurality of cells b1, b2, b3, b4, the current flowing through the cell becomes zero and the current flows through the other cells. This also indicates that a large amount of current flows through the cell having a low initial voltage, and the amount of charge increases.

FIG. 10B shows waveforms of the current i _cn1 and the current i _cf1 when the gate signal shown in FIG. 10A is given to the switch 21. The current i _cn1 flows from the secondary coil 51 to the cell b1 and the capacitor 71. The current i _cf1 flows through the cell b1. Here, the initial voltage V _o1 of the cell b1 is 3.72 V, the initial voltage V _o2 of the cell b2 is 3.58 V, the initial voltage V _o3 of the cell b3 is 3.26 V, and the initial voltage V of the cell b4 _o4 was set to 2.90 V (V _o1 > V _o2 > V _o3 > V _o4 ).

As shown in FIG. 10B, the current i _cn1 starts to decrease after rising to about 3A at the moment when the switch is turned off (300 [μs], 350 [μs]), and the current i _cn1 is 310 [μs] and 360 [μs]. Nearly zero. The average value of the current i _cn1 was about 0.18A. Similarly to the current i _cn1 , the current i _cf1 rises at the moment when the switch is turned off. However, since a part of the current i _cn1 flows to the capacitor 71, immediately after the switch is turned off, the current i _{cn1 is} higher than the current i _cn1. Few. However, even after the current i _cn1 becomes _{substantially zero} , the current i _cf1 slightly flows into the cell b1 due to the electric charge charged in the capacitor 71.

FIG. 10C shows the charge amount of the cell b1 when the current i _cf1 shown in FIG. 10B flows. As shown in FIG. 10C, the cell b1 was charged with about 8.8 μC in one switching cycle.

FIG. 11B shows waveforms of the current i _cn2 and the current i _cf2 when the gate signal shown in FIG. 11A is supplied to the switch 21. The current i _cn2 flows from the secondary coil 52 to the cell b2 and the capacitor 72. The current i _cf2 flows through the cell b2. The initial voltages of the cells b1, b2, b3, and b4 are the same as those in FIG. 10B.

As shown in FIG. 11B, the current i _cn2 rises to about 3A at the moment when the switch is turned off (300 [μs], 350 [μs]) and then decreases to 310 [μs] and 360 [μs]. Nearly zero. The average value of the current i _cn2 was about 0.20A.

FIG. 11C shows the charge amount of the cell b2 when the current i _cf2 shown in FIG. 11B flows. As shown in FIG. 11C, the cell b2 was charged with about 10 μC in one switching cycle.

FIG. 12B shows waveforms of the current i _cn3 and the current i _cf3 when the gate signal shown in FIG. 12A is given to the switch 21. The current i _cn3 flows from the secondary coil 53 to the cell b3 and the capacitor 73. The current i _cf3 flows through the cell b3. The initial voltages of the cells b1, b2, b3, and b4 are the same as those in FIG. 10B.

As shown in FIG. 12B, the current i _cn3 rises to about 3.9 A at the moment when the switch is turned off (300 [μs], 350 [μs]) and then decreases to 310 [μs] and 360 It becomes almost zero before [μs]. The average value of the current i _cn3 was about 0.29A.

FIG. 12C shows the charge amount of the cell b3 when the current i _cf3 shown in FIG. 12B flows. As shown in FIG. 12C, the cell b3 was charged with about 14.4 μC in one switching cycle.

FIG. 13B shows waveforms of the current i _cn4 and the current i _cf4 when the gate signal shown in FIG. 13A is given to the switch 21. The current i _cn4 flows from the secondary coil 54 to the cell b4 and the capacitor 74. The current i _cf4 flows through the cell b4. The initial voltages of the cells b1, b2, b3, and b4 are the same as those in FIG. 10B.

As shown in FIG. 13B, the current i _cn4 rises to about 3.4 A at the moment when the switch is turned off (300 [μs], 350 [μs]) and then decreases to 310 [μs] and 360 It becomes almost zero before [μs]. The average value of the current i _cn4 was about 0.34A.

FIG. 13C shows the charge amount of the cell b4 when the current i _cf4 shown in FIG. 13B flows. As shown in FIG. 13C, the cell b4 was charged with about 16.8 μC in one switching cycle.

  As shown in FIGS. 10A to 13C, it was confirmed that a larger amount of current flows through the low-voltage cell, and that the lower-voltage cell is charged more. Therefore, on the secondary side of the transformer 40, even when the controller 110b does not perform active control, balancing of a plurality of cells is automatically performed.

[3. Deformation]

  The present invention is not limited to the above embodiment, and various modifications can be made. For example, in the balancer circuit 110a, the primary side of the transformer 40 may be provided with a snubber circuit that absorbs a high voltage generated when the switches 21 and 22 are OFF.

  In addition, the balancer 110 has not only a function of performing a balanced discharge of the battery 120 to charge the battery 130, but also a function of performing a balanced discharge of the battery 130 to charge the battery 120 in a balanced manner. good. In order to discharge the battery 130 and charge the battery 120, the diodes 61, 62, and 63 in FIG. 3 may be replaced with switches similar to the switches 21 and 22.

11 Primary coil 12 Primary coil 21 Switch 22 Switch 31 Voltage measuring instrument 32 Voltage measuring instrument 40 Transformer 41 Magnetic core 51 Secondary coil 52 Secondary coil 53 Secondary coil 54 Secondary coil 61 Diode 62 Diode 63 Diode 64 Diode 71 Capacitor 72 Capacitor 73 Capacitor 100 Power supply 110 Balancer 110a Balancer circuit 110b Controller 120 Traveling battery 130 Auxiliary battery 140 EPS converter 150 Motor a1 Cell a2 Cell b1 Cell b2 Cell b3 Cell b4 Cell

Claims (8)

  A transformer having at least one primary coil connected to the first assembled battery and a plurality of secondary coils connected to a plurality of cells constituting a second assembled battery different from the first assembled battery. A flyback converter type balancer. The balancer according to claim 1, wherein the at least one primary coil is a plurality of primary coils connected to a plurality of cells constituting the first assembled battery. The balancer according to claim 2, further comprising a plurality of switches that turn on / off current flows from the plurality of cells constituting the first assembled battery to the plurality of primary coils. The balancer according to claim 3, further comprising a controller that turns on one of the plurality of switches and turns off the other switch based on voltages of the plurality of cells constituting the primary assembled battery. . A first assembled battery;
A second assembled battery;
A transformer having a plurality of primary coils through which a current flows from a plurality of first cells constituting the first assembled battery, and a plurality of secondary coils through which a current flows to a plurality of second cells constituting the second assembled battery A flyback converter type balancer comprising:
A power supply device comprising: The first assembled battery is a battery for driving an automobile,
The power supply device according to claim 5, wherein the second assembled battery is an auxiliary battery for an automobile. Using the transformer having a plurality of secondary coils connected to the plurality of cells constituting the assembled battery, the plurality of the plurality of cells connected to the plurality of cells by the energy stored from the primary side by the flyback converter method A balancing method in which the plurality of cells are balance-charged by being discharged from the secondary coil. The balancing method according to claim 7, wherein the energy accumulated from the primary side is obtained by performing a balanced discharge on a plurality of cells constituting an assembled battery different from the assembled battery.