JP6493172B2 - Battery connection method - Google Patents

Description

  The present invention relates to a battery parallel connection method in a battery power supply apparatus configured by connecting a plurality of batteries in parallel.

  The term “battery” as used herein refers to a so-called column battery or battery assembly composed of a number of batteries connected in series, although it can include one battery in principle. A battery power supply device configured by connecting a plurality of such row batteries in parallel is used in a so-called hybrid power supply system such as an electric vehicle or an electric propulsion ship having a power generation device for charging the battery. In this type of system, it is necessary to connect a plurality of batteries in parallel when assembling the battery power supply, and a new battery is connected in parallel to an existing battery in order to replace a battery having deteriorated characteristics during use. There is a need. When batteries are connected in parallel in this way, if there is even a voltage difference between the batteries connected in parallel, an excessive inrush current will flow between the batteries, causing damage to the batteries and operating the protection device provided in the circuit. Problems occur.

  In particular, in a large-capacity battery power source using a lithium ion battery, since the internal resistance of the battery is very small, only a slight voltage difference occurs between two batteries connected in parallel due to variations in battery characteristics. However, when batteries are connected in parallel, an excessive inrush current flows, and preventing this is an important issue.

  In order to prevent such an excessive inrush current at the time of parallel connection of batteries in a battery power supply, as shown in Patent Document 1, a bidirectional chopper circuit is connected between both batteries connected in parallel, and this chopper circuit There is already known a method of performing parallel connection after equalizing the voltages of both batteries to the same voltage while suppressing the current flowing between the two batteries.

JP 2015-019447 A

  According to the battery parallel connection method using the above-described conventional bidirectional chopper circuit, when the batteries are connected in parallel, an inrush current due to a voltage difference flowing between the batteries connected in parallel can be suppressed. Battery damage due to current can be avoided.

  The present invention improves the battery parallel connection method using the bidirectional chopper circuit, and causes the current flowing between the batteries to flow up to the maximum current allowed for the battery during the pressure equalizing operation before the parallel connection. It is an object of the present invention to provide a battery parallel connection method capable of shortening the voltage equalization time between the batteries connected in parallel and performing the parallel connection work quickly.

In order to solve the above problems, the present invention, when connecting a new battery in parallel to an existing battery constituting a battery power source or the like, connects the new battery in parallel via a connection switch to the existing battery, and By connecting the bi-directional chopper circuit by bypassing the connection switch between the two batteries connected in parallel, opening the connection switch, and charging / discharging current flowing between the two batteries based on the voltage difference between the two batteries. In a parallel connection method of batteries in which the voltage of both batteries is equalized by the intermittent control of the bidirectional chopper circuit, and then the connection switch is turned on to connect the batteries in parallel.
When performing the pressure equalization operation of the batteries by the intermittent control of the bidirectional chopper circuit, the maximum value of the charge / discharge current flowing between the batteries through the bidirectional chopper circuit is less than the maximum allowable current of the batteries. Thus, the intermittent ratio of the bidirectional chopper circuit is controlled.

  In the present invention, the intermittent ratio of the bidirectional chopper circuit is controlled to be intermittent, and the current flowing through the bidirectional chopper circuit during the on period of the bidirectional chopper circuit is the maximum allowable value of each battery. The reactance of the reactor of the bidirectional chopper circuit can be selected so as to reach current.

  Also, in the present invention, a plurality (N) of the bidirectional chopper circuits are provided, the plurality of bidirectional chopper circuits are connected in parallel, and the intermittent control of each bidirectional chopper circuit is mutually controlled by 1 / of the intermittent period. Multiple operations can be performed while shifting by N periods.

  In the present invention, when the current flowing through the bidirectional chopper circuit is zero, the switching element of the bidirectional chopper circuit is turned on, and the current is turned on when the current reaches the maximum allowable current of each battery. It is preferable to perform intermittent control of the bidirectional chopper circuit by turning off the switching element.

  Before the two batteries are connected in parallel to each other, the charging that flows between the two batteries due to the voltage difference between the two batteries is performed in the pressure equalization process by controlling the bidirectional chopper circuit connected between the two batteries intermittently. Since charging / discharging between both batteries is performed while keeping the maximum value of the discharging current at the maximum allowable current of each battery, the charging / discharging current between both batteries can be set to the maximum allowable current. Voltage equalization time can be shortened, and battery parallel connection work can be performed quickly.

The circuit block diagram which shows the 1st Example for enforcing the connection method of this invention. FIG. 3 is a current path diagram for explaining the operation of the first embodiment of the present invention. FIG. 3 is an operation waveform diagram of the chopper circuit for explaining the operation of the first embodiment of the present invention. FIG. 3 is a time lapse diagram of voltage and current for explaining the operation of the first embodiment of the present invention. The circuit block diagram which shows the 2nd Example for enforcing the connection method of this invention. The operation waveform diagram of the chopper circuit for explaining the operation of the second embodiment of the present invention. The circuit block diagram which shows the 3rd Example for implementing the connection method of this invention. The operation waveform diagram of the chopper circuit for explaining the operation of the third embodiment of the present invention. The operation waveform diagram of the chopper circuit for explaining the applied operation of the third embodiment of the present invention. The circuit block diagram which shows the 4th Example for enforcing the connection method of this invention. The operation waveform diagram of the chopper circuit for demonstrating operation | movement of the 4th Example of this invention.

  Embodiments of the present invention will be described with reference to the embodiments shown in the drawings.

  FIG. 1 is a circuit diagram showing a first embodiment for carrying out the connection method of the present invention.

  In FIG. 1, reference numeral 1 denotes an existing battery circuit constituting a battery power source. The battery circuit 1 includes, for example, a battery B1 made of a lithium ion battery having a small internal resistance RB1 and a switch S1 that opens and closes a battery circuit preferably composed of a mechanical switch connected in series therewith.

  Reference numeral 2 denotes a new battery circuit connected in parallel to the existing battery circuit 1 constituting the battery power source. The battery circuit 2 is also composed of a battery B2 made of a lithium ion battery having a small internal resistance RB2 like the battery circuit 1, and a switch S2 made of a mechanical switch, preferably connected in series. The

  The batteries B1 and B2 may be a single battery, or may be a column battery configured by connecting a plurality of batteries in series, and are simply referred to as batteries here.

  Reference numeral 3 denotes a bidirectional chopper circuit. The bidirectional chopper circuit 3 includes a diode bridge circuit DB and a chopper circuit CH. The diode bridge circuit DB is configured by bridge-connecting four diodes D11 to D14. The chopper circuit CH is configured by connecting a switching element Q, which is configured by connecting a switching transistor T and a diode D5 in antiparallel, and a reactor L in series, and connecting a freewheeling diode D6 to a connection point between the switching element Q and the reactor L. The A bidirectional chopper circuit 3 is configured by connecting a chopper circuit CH between the DC side terminals of the diode bridge circuit DB.

  The bidirectional chopper circuit 3 includes input / output terminals A1 and A2 drawn from the diode bridge circuit DB, a negative terminal F drawn from the freewheeling diode D6, and a control terminal G drawn from the gate terminal of the switching transistor T.

  When the battery circuit 2 is connected in parallel to the battery circuit 1, the switch S2 of the battery circuit 2 is turned off and the terminals T2 and N2 at both ends thereof are connected to the terminals T1 and N1 at both ends of the battery circuit 1. The input / output terminals A1 and A2 of the bidirectional chopper circuit 3 are connected between the positive terminal P2 of the battery circuit 2 and the terminal T2 so as to bypass the switch S2 on the battery circuit 2 side. Thereby, the battery B2 of the battery circuit 2 is connected in parallel to the battery B1 of the battery circuit 1 via the bidirectional chopper circuit 3. The negative terminal F of the bidirectional chopper circuit 3 is connected to the negative terminal N1 of the battery circuit 1 and the negative terminal N2 of the battery circuit 2 in common. The control terminal G is connected to the chopper control circuit CTR.

  A voltage detector VD is connected between the DC terminals connected to the chopper circuit CH of the diode bridge circuit DB, and detects a difference voltage ΔVB between the voltage VB1 of the battery B1 and the voltage VB2 of the battery B2. The voltage difference ΔVB between the battery B1 and the battery B2 detected by the voltage detector VD is input to the voltage determination unit VC. When the voltage VB1 of the battery B1 is equal to the voltage VB2 of the battery B2 and ΔVB becomes zero, the voltage determination unit VC generates a determination output Vc and applies it to the chopper control circuit CTR. When the determination output Vc is applied from the voltage determination unit VC, the chopper control circuit CTR stops the intermittent control signal GS to the switching element Q of the chopper circuit CH and stops the operation of the chopper circuit CH.

  In the present invention, the bidirectional chopper circuit 3 is used regardless of whether the voltage VB1 of the existing battery B1 on the battery power supply side or the voltage VB2 of the battery B2 connected in parallel to this is higher or lower. In addition, the current adjustment chopper circuit CH can be freely connected between the batteries.

  That is, when the voltage VB2 of the battery B2 is higher than the voltage VB1 of the battery B1, when the switching element Q of the chopper circuit CH is turned on, as shown by the solid line arrow in FIG. A charging current I2 flows and the battery B1 can be charged by the battery B2. Further, when the voltage VB1 of the battery B1 is higher than the voltage VB2 of the battery B2, the connection of the bidirectional chopper circuit 3 is not changed, but when the switching element Q of the chopper circuit CH is turned on, as shown by a dotted arrow in FIG. The charging current I1 flows from the battery B1 to the battery B2 through the chopper circuit CH, and the battery B2 can be charged by the battery B1.

  In the present invention, the battery having the lower voltage is charged from the battery having the higher voltage of the two batteries connected in parallel as described above, and this is executed until the voltages of both the batteries become equal. When the voltages of both batteries become equal, the difference voltage ΔVB between the two batteries becomes 0, and the voltage determination unit VC detects this and applies the determination output Vc to the chopper control circuit CTR. As a result, when the chopper circuit CH stops the intermittent operation, by switching on (turning on) the battery circuit to be connected in parallel, the two batteries can be safely connected in parallel without inrush current.

  Next, a parallel connection method according to the first embodiment of the present invention will be described.

  This is a connection method in the case where a new external battery circuit 2 having a battery B2 is connected in parallel to the battery B1 of the existing battery circuit 1 constituting the battery power source in FIG. .

  Here, it is assumed that the voltage VB2 of the initially charged battery B2 is higher than the voltage VB1 of the existing battery B1 (VB2> VB1). Of course, the voltage VB1 of the battery B1 may be higher than the voltage VB2 of the battery B2 (VB1> VB2).

  The switch S1 of the battery circuit 1 constituting the battery power supply is turned on to supply power from the battery B1 to a load not shown here.

  The switch S2 is turned off and the terminals T2 and N2 at both ends of the battery circuit 2 are connected to the terminals T1 and N1 at both ends of the battery circuit 1. The input / output terminals A1 and A2 of the bidirectional chopper circuit 3 are connected to the terminals P2 and T2 at both ends of the switch S2 of the battery circuit 2, and the negative terminal F of the chopper circuit 3 is connected to the negative terminals N1 and N2 of the battery circuits 1 and 2. Connect in common. As a result, the battery B2 of the battery circuit 2 bypasses the switch S2 and is connected in parallel to the battery B1 of the battery circuit 1 via the bidirectional chopper circuit 3.

  After such a connection is made, an intermittent control signal in which the conduction rate is 50% at a predetermined period T as shown in FIG. 3A from the chopper control circuit CTR to the gate of the switching element Q of the chopper circuit 3 GS is added to control the switching element Q intermittently (on / off). The conduction ratio of 50% is that the ON period α of the intermittent control signal GS is 50% with respect to the intermittent period T. This is the same as setting the intermittent ratio (α / β) of the intermittent control signal to 1 because the ON period α and the OFF period β of the intermittent control signal GS are equal.

  In the period α during which the switching element Q is turned on, the current IQ flows through the chopper circuit CH from the battery B2 on the higher voltage side through the switching element Q and the reactor L as shown in FIG. As shown in FIG. 2, the current IQ is discharged from the battery B2 of the battery circuit 2 and becomes a current I2 for charging the battery B1 of the battery circuit 1.

  The current IQ flowing through the chopper circuit CH starts to flow when the intermittent control signal GS rises at the time t0 and is turned on, but starts to flow, but is limited by the reactor L. Therefore, the current IQ shown in FIG. So that it rises over time. The value of the reactance Lx of the reactor L is selected so that the current IQ reaches the predetermined maximum allowable current Ip of the batteries B1 and B2 at the end of the ON period α, that is, at the time t1. For this reason, the current IQ rises only to Ip in the ON period α of the chopper circuit CH, and does not become larger than this.

  When the intermittent control signal GS falls and is turned off, the switching element Q is turned off. When the switching element Q is turned off, the current supplied from the battery B2 is cut off, but the reactor L supplies the return current IL to the battery B1 through the return diode D6 by the energy accumulated by the current when the switching element Q is turned on. Continues to flow and charging continues. As the return current IL is consumed by the energy stored in the reactor L, it gradually decreases from Ip as shown by the dotted line in FIG. 3B, and the off period β is selected as a period equal to the on period α. Therefore, it becomes 0 at the end of the off period β, that is, at the time t2 when the intermittent control signal GS rises from the off state to the on state.

  Subsequently, the switching element Q intermittently interrupts the current between the two batteries in response to the on / off switching control signal GS, whereby the reactor L has a maximum value as shown by a solid line and a dotted line in FIG. A triangular wave current that is the maximum allowable current Ip of the specified battery flows at a predetermined period T, and the maximum value of the charge / discharge current flowing between the batteries B2 and B1 is limited to the maximum allowable current Ip of the battery.

  As a result, a sawtooth wave discharge current IB2 whose maximum value is limited to Ip flows through the bidirectional chopper circuit 3 from the battery B2 having a higher voltage as shown in FIG. The battery B1 having a lower voltage is added with the reflux current IL of the reactor L to this current, so that a triangular wave charging current IB1 whose maximum value is limited to Ip as shown in FIG. Flowing. Thereby, the battery B1 with the lower voltage is charged from the battery B2 with the higher voltage.

  Thus, when the new battery B2 is connected in parallel to the existing battery B1 constituting the battery power supply 1, the battery B2 is connected in parallel to the battery B1 via the bidirectional chopper circuit 3, and this bidirectional chopper circuit 3 By controlling intermittently, charging / discharging between both batteries can be performed while limiting the maximum value of the charging / discharging current flowing between both batteries to the maximum allowable current of the specified battery. As a result, the battery voltage VB2 of the battery B2 with the higher voltage gradually decreases, and the battery voltage VB1 of the battery B1 with the lower voltage gradually increases so that the voltages of both batteries approach rapidly and in a short time. Will be equal.

  When the battery voltages of both the batteries B1 and B2 become equal, the voltage ΔVB detected from the voltage detector VD in FIG. 1 becomes 0. Therefore, the voltage determination unit VC detects this, generates a determination output Vc, and performs chopper control. Add to circuit CTR. As a result, the intermittent control signal GS given to the switching element Q by the chopper control circuit CTR is stopped, so that the chopper circuit CH stops the intermittent operation. When the chopper circuit CH stops the intermittent operation, the battery circuit 2 can be connected in parallel to the battery circuit 1 without inrush current by automatically or manually turning on the switch S2 of the battery circuit 2 and turning it on. .

  FIG. 4 shows temporal changes in the voltage (VL) of the chopper CH and the charging current (IB1) supplied to the battery B1 on the lower voltage side in the pressure equalizing operation process for equalizing the battery voltages. Here, the voltage (VL) is a difference voltage from the voltage VB2 of the higher battery B2 with reference to the voltage VB1 of the lower battery B1, and is indicated by a solid line. In addition, as for the current, a current IB1 for charging the battery B1 having a lower voltage is indicated by a dotted line.

  As is apparent from this figure, from the start time t0 when the difference voltage ΔVB between the two voltages becomes the maximum ΔVB1, from the start time t0 until the voltage difference ΔVB decreases to a predetermined ΔVBm, the charging current IB1 is maximum even if the difference voltage ΔVB is large. The current is suppressed to the maximum allowable current Ip of the battery.

  When the difference voltage ΔVB is lower than the predetermined voltage ΔVBm, the maximum current of the charging current IB1 is suppressed due to the decrease of the difference voltage ΔVB. Therefore, the maximum current gradually decreases from the maximum allowable current Ip as the difference voltage ΔVB decreases, and the time tx Thus, when the voltages of both batteries become equal and the difference voltage ΔVB becomes 0, it becomes 0. As a result, the intermittent operation of the chopper circuit CH is stopped, and the voltage equalizing operation of both batteries is stopped.

  Here, the switch S2 is turned on to connect the battery circuit 2 to the battery circuit 1 in parallel. At this time, since the difference voltage ΔVB between the two batteries is 0, the two batteries can be safely connected in parallel without inrush current.

  A second embodiment of the present invention is shown in FIG.

  In the second embodiment, two bidirectional chopper circuits 31 and 32 are connected in parallel via a switch S3 between a battery circuit 1 constituting a battery power source and a new battery circuit 2 connected in parallel thereto. Connected.

  When the batteries are connected in parallel, as in the first embodiment, the switch S1 is turned on, the switch S2 is turned off, the switch S3 is turned on, and the bidirectional chopper circuits 31 and 32 are intermittently operated to equalize the voltages of both batteries. When the voltage difference ΔVB between the two batteries is zero, the switch S2 is turned on to perform parallel charging.

  The voltage equalizing operation of the battery voltage by the bidirectional chopper circuits 31 and 32 will be described with reference to the operation waveform diagram shown in FIG.

  The switching elements Q1 and Q2 of the chopper circuits CH1 and CH2 of the bidirectional chopper circuits 31 and 32 have a ratio of the intermittent period α and β in the period T of 1 as shown in FIGS. The intermittent control signals GS1 and GS2 are given with a phase shift of T / 2.

  As a result, the chopper circuits CH1 and CH2 perform intermittent control of voltage and current with a phase shifted by ½ of the cycle T of the intermittent control signal as shown in FIGS. 6 (b1) and (b2). The currents IQ1 and IQ2 flowing in the chopper circuits CH1 and CH2 are set to the maximum allowable current Ip of the batteries B1 and B2 defined in advance in a half cycle (T / 2) of the respective cycles. Since the reactances of the reactors L1 and L2 are selected, the maximum values of the currents IQ1 and IQ2 flowing through the chopper circuits CH1 and CH2 are limited to Ip.

  Since the chopper circuits CH1 and CH2 operate with a half cycle (T / 2) shifted from the intermittent cycle T, the current IB2 discharged from the new battery B2 on the side connected in parallel to the existing battery B1 is shown in FIG. ), The maximum value that changes in the T / 2 period is an Ip sawtooth wave.

  The battery B1 is supplied from the chopper circuits CH1 and CH2 with a charging current due to the discharge current IB2 from the battery B2 and a charging current due to the accumulated energy of the reactors L1 and L2 of each chopper circuit. The charging currents IQ1 and IQ2 supplied from the chopper circuits CH1 and CH2 to the battery B1 are triangular wave currents having a maximum value Ip, and flow with a half cycle (T / 2) as shown in FIG. 6D. . Since the charging current IB1 supplied to the battery B1 is a current obtained by combining (adding) the currents IQ1 and IQ2 of the chopper circuits CH1 and CH2, a constant current Ip as shown by a solid line IB1 in FIG. It becomes.

  Thus, according to the second embodiment, when charging the battery with the lower voltage from the battery with the higher voltage to equalize the voltages of both batteries, the charging current is set to the maximum allowable current Ip of the battery. Therefore, the voltage equalization time of both battery voltages can be further shortened.

  By performing the voltage equalizing operation of the battery voltage between the two batteries B1 and B2 by the two chopper circuits 31 and 32, the parallel connection is established when the voltage difference ΔVB between the two batteries becomes zero. The battery circuit 2 is connected in parallel to the battery circuit 1 by turning on (turning on) the switch S2 of the new battery circuit 2 on the side to be operated. Thereafter, the bidirectional chopper circuits 31 and 32 can be disconnected from the battery circuits 1 and 2 after the switch S3 is turned off.

  A third embodiment of the present invention is shown in FIG.

  In this embodiment, a plurality of bidirectional chopper circuits are connected in parallel between two batteries for parallel connection of the batteries.

  The embodiment of FIG. 7 includes a battery power source BP configured by connecting a plurality of battery circuits 11 to 1n in parallel. The battery power supply BP is connected to a load LO via a switch SL, and a charging device BC including a generator G via a switch SG for charging the batteries B11 to B1n constituting the battery power supply BP. Is connected.

  In order to replace any one battery circuit of the battery power supply BP, a new battery circuit 2 is provided outside. When the new battery circuit 2 is connected in parallel to the battery power supply BP, the terminals T2 and N2 at both ends thereof are connected in parallel to the output terminal of the battery power supply BP with the switch S2 turned off.

  A bidirectional chopper circuit 30 connected between the battery B2 of the battery circuit B2 and the batteries (B11 to B1n) of the battery power source to equalize the voltage between the two batteries includes a plurality of bidirectional chopper circuits 31. To 34 are connected in parallel. The bidirectional chopper circuit 30 including the plurality of bidirectional chopper circuits 31 to 34 is connected between the positive terminal P2 and the output terminal T2 of the battery circuit 2 and the negative terminal N2 via the switch S3.

  In FIG. 7, the chopper circuits 33 and 34 of the bidirectional chopper circuit 30 are shown as blocks in which the internal configuration is omitted, but include a bidirectional chopper circuit configured similarly to the chopper circuits 31 and 32. The chopper control circuit CTR is also connected in parallel so as to be operable in cooperation.

  In this embodiment, when a plurality of bidirectional chopper circuits 31 to 34 of the bidirectional chopper circuit 30 are operated in a double parallel manner as in the second embodiment, for example, two bidirectional chopper circuits 31 and 32 are selected. Thus, the double parallel operation is performed by shifting each intermittent period T by ½ period.

  When performing triple parallel operation, three bidirectional chopper circuits 31, 32, 33, for example, are selected from the plurality of bidirectional chopper circuits 31 to 34, and the intermittent period T is set to 1/3. Perform intermittent operation by shifting the cycle.

  FIG. 8 shows waveforms of voltages, currents, and signals at various parts when triple parallel operation is performed.

  The intermittent control signals G1, G2, and G3 from the control circuit CTR to the chopper circuits 31, 32, and 33 are 1/3 of the intermittent period T as shown in FIGS. 8 (a1), (a2), and (a3). The chopper circuits 31, 32 and 33 are intermittently operated with a shift of 1/3 period of the intermittent period T. The intermittent ratio (α / β) of each intermittent control signal is set to 1.

  For this reason, the voltage and current applied to the chopper circuits 31, 32, and 33 change as shown in FIGS. 6 (b1), (b2), and (b3). In this case, the reactance of the reactor L of each chopper circuit is such that the current of each chopper circuit reaches the specified maximum allowable current Ip of the batteries B11 to B1n and B2 at the time of ½ period of the intermittent period T of each chopper. Lx is selected. For this reason, the currents IQ1, IQ2, and IQ3 of the respective chopper circuits flow with a maximum value limited to the maximum allowable current Ip and shifted from each other by 1/3 of the intermittent period T.

  When the voltage VB2 of the new battery B2 on the side connected in parallel is higher than the voltage VB1 of the battery B1 of the battery power supply BP, the chopper circuit currents IQ1, IQ2, IQ3 from the battery B2 by the intermittent operation of the chopper circuits 31, 32, 33. The discharge current IB2 obtained by synthesizing (adding) the above flows. The discharge current IB2 is a sawtooth wave as shown in FIG. 8C, and the maximum value exceeds the maximum allowable current Ip of the battery, but the average current Ia is suppressed to be equal to or less than the maximum allowable current Ip.

  The batteries B1 to Bn on the side of the battery power supply to be charged have the energy stored in the reactor L when the discharge current from the battery B2 and the switching element Q of each chopper circuit 31, 32, 33 are on. Charging is performed by currents IQ1, IQ2, and IQ3, which are combined with the current discharged through the freewheeling diode when (1-3) is off. The charging current IB1 obtained by combining (adding) the currents IQ1, IQ2, and IQ3 becomes a pulsating current whose maximum value exceeds the maximum allowable current Ip as shown in FIG. 8D, and the average value Ia also exceeds Ip. In the battery power supply BP, since the current IB1 is distributed to the plurality of battery circuits 11 to 1n, the battery charging current of each battery circuit does not exceed the maximum allowable current Ip.

  By charging the battery having the lower voltage from the battery having the higher voltage between the two batteries in this way, the difference voltage ΔVB between the two batteries is rapidly reduced toward zero. When the differential voltage ΔVB becomes 0, the pressure equalizing operation by the intermittent operation of the chopper circuit is stopped, the switch S2 of the battery circuit 2 on the side connected in parallel is turned on, and the battery circuit 2 is changed to the battery circuit 1. Connect in parallel. Thereby, since inrush current at the time of parallel connection of batteries can be eliminated, parallel connection of batteries can be performed safely.

  In the third embodiment, when the four bidirectional chopper circuits are operated in parallel by performing quadruple parallel operation, the bidirectional chopper circuit 30 in FIG. Double parallel operation.

  FIG. 9 shows waveforms of voltage, current, and signal during the quadruple parallel operation. The pressure equalizing operation will be described with reference to this figure.

  As shown in FIGS. 9A1 to 9A4, the intermittent control signals G1 to G4 are given to the switching elements Q1 to Q4 of the four chopper circuits while being shifted by a quarter period of the intermittent period T. The intermittence ratio α / β of each intermittence control signal is set to 1 as in the above embodiments.

  For this reason, the currents IQ1 to IQ4 flowing through the chopper circuits 31 to 34 change as shown in FIGS. 9B1 to 9B4. In this case, the current of each chopper circuit 31 to 34 reaches the maximum allowable current Ip defined for the batteries B11 to B1n and B2 at the time of 1/2 of the intermittent period T of each chopper circuit. The reactance of the reactors L1 to L4 is selected. For this reason, the currents IQ1 to IQ4 of the chopper circuits flow with their maximum values limited to the maximum allowable current Ip and shifted from each other by a quarter of the intermittent period T.

  When the voltage VB2 of the new battery B2 on the side connected in parallel is higher than the voltage VB1 of the battery B1 of the battery power supply BP, the current flowing from the battery B2 to each chopper circuit by the intermittent operation of the chopper circuits 31 to 34 is shown in FIG. The sawtooth wave currents IQ1 to IQ4 as shown in FIG. Although the maximum value of these currents does not exceed the maximum allowable current Ip of the battery, the discharge current IB2 flowing from the battery B2 is a current obtained by combining these currents, so that the current is 1.5 times the maximum allowable current Ip. It becomes.

  The battery B1 on the battery power supply side to be charged is such that the discharge current from the battery B2 and the magnetic energy stored in the reactor L when the switching elements Q of the chopper circuits 31 to 34 are turned on return when the switching element Q is turned off. Charging is performed by currents IQ1 to IQ4 obtained by combining the current discharged through the diode. The charging current IB1 obtained by synthesizing the currents IQ1 to IQ4 is a linear current twice as large as the maximum allowable current Ip, as shown in FIG. 9 (d).

  For this reason, when the four chopper circuits are operated in quadruple in parallel to perform the pressure equalizing operation, the chopper circuits 31 to 31 are maintained so that the discharge current IB2 and the charging current IB1 are maintained at the maximum allowable current Ip. By reducing the current conduction ratio of 34 (the ratio of the on period α to the intermittent period T of the switching element Q) to 50% or less, damage to the battery on the discharge side and the battery on the charge side is avoided.

  By charging the battery having the lower voltage from the battery having the higher voltage between the two batteries in this way, the difference voltage ΔVB between the two batteries is rapidly reduced toward zero. When the differential voltage becomes 0, the voltage equalization operation by the intermittent operation of the chopper circuit is stopped, the switch S2 of the battery circuit 2 on the side to be connected in parallel is turned on, and the battery circuit 2 is connected in parallel with the battery circuit 1. Connecting. Thereby, an inrush current is prevented from flowing when the batteries are connected in parallel, and the batteries can be safely connected in parallel.

  A fourth embodiment of the present invention is shown in FIG.

  The fourth embodiment shown in FIG. 4 basically has the same configuration as that of the first embodiment shown in FIG. However, the current detector ID for detecting the current IL of the chopper circuit CH in series with the reactor L of the chopper circuit CH and the detection output IL of the current detector ID are compared with a preset current setting value IP to detect the detection current IL. Is different from the first embodiment in that a current determination unit IC that generates a determination output Ic is provided when the current becomes equal to or greater than the set current IP.

  The determination output Ic of the current determination unit IC is applied to the chopper control unit CTR together with the determination output Vc of the voltage determination unit VC that determines that the differential voltage ΔVB has become zero.

  The chopper controller CTR includes an intermittent control signal generator CSG that generates an intermittent control signal GS. The intermittent control signal generation unit CSG generates an ON signal at a constant period T, but when a determination output Ic is applied from the current determination unit IC, an operation to generate an intermittent control signal GS that turns the ON signal OFF from that point. do. Further, when the determination output Vc is applied from the voltage determination unit VC, the chopper control unit CTR stops the intermittent control signal GS applied from the intermittent control signal generation unit CSG to the chopper circuit CH.

  In the fourth embodiment, as shown in FIG. 10, the battery voltage equalizing operation when the new battery circuit 2 is connected to the existing battery circuit 1 constituting the battery power source is shown in the operation waveform diagram of FIG. The description will be given with reference.

  The battery circuit 2 turns off the switch S2, and connects the terminals T2 and N2 at both ends thereof to the terminals T1 and N1 at both ends of the battery circuit 1. The input / output terminals A1 and A2 of the bidirectional chopper circuit 3 are connected to the terminals P2 and T2 at both ends of the switch S2, the negative terminal F is commonly connected to the negative terminals N1 and N2 of the battery circuits 1 and 2, and An intermittent control signal GS intermittently applied at a constant period T from the chopper controller CTR is applied to the gate terminal G.

  Thereby, the bidirectional chopper circuit 3 operates intermittently, and intermittently controls the current flowing between the battery B1 of the battery circuit 1 and the battery B2 of the battery circuit 2. This current flows from the battery B2 having the higher voltage to the battery B1 having the lower voltage, and the battery B1 is charged from the battery B2.

  The chopper circuit CH is turned on when the intermittent control signal GS applied from the chopper control circuit CTR is turned on at time t0, and the difference voltage ΔVB (= VB2−) between the voltage VB2 of both the batteries B2 and the voltage VB1 of the batteries B1. The current IL rises as shown in FIG. 11 (c) with a slope determined based on VB1) and the reactor L. The current detection circuit ID detects the current IL at this time, and the current determination unit IC determines whether or not the current IL has reached the determination setting current Ip that is set in advance to the maximum allowable current of the battery. When the current IL reaches the set current Ip at time t1, the current determination unit IC generates a determination output Ic, and the intermittent control signal of the chopper control unit CTR is applied to the generation unit CSG.

  As a result, the intermittent control signal generation unit CSG immediately turns off the intermittent control signal GS that is on level as shown in FIG. Accordingly, the chopper circuit CH is turned off and the charging current supplied from the battery B2 to the battery B1 is cut off. However, since the reflux current continues to flow in the battery B1 due to the energy accumulated in the reactor L, the chopper circuit CH The current IL falls with a constant slope as shown in FIG.

  At time t2 when the next cycle T is started, the intermittent control signal GS is turned on again and becomes an on level. As a result, the chopper circuit CH is turned on, and the chopper circuit current IL rises again. When this current reaches the set current Ip again at time t3, this is detected by the current determination unit IC, and the determination output Ic is added to the intermittent control signal generation unit CSG. Thereby, since the intermittent control signal GS to the chopper circuit CH is turned off, the current IL falls at a predetermined slope, and at the time t4 when the next period T is reached, the intermittent control signal GS from the intermittent control signal generation unit CSG. Is turned on, the chopper circuit CH is turned on again and the current IL rises, and thereafter the same operation is repeated.

  As a result, the battery B1 having the lower voltage is charged by the current supplied from the battery B2 having the higher voltage, and the voltage VB2 of the battery B2 having the higher voltage is reduced due to the discharge. Since the voltage VB1 of the lower battery B1 rises due to charging, the difference voltage ΔVB between the two batteries rapidly goes to 0 as shown in FIG. 11A, and becomes 0 at the time tx after a predetermined time has elapsed. .

  When the differential voltage ΔVB becomes 0, the voltage determination unit VC detects this, adds the determination output Vc to the intermittent control signal generation unit CSG, and stops its operation. As a result, the intermittent control signal GS output from the intermittent control signal generation unit CSG is stopped, so that the chopper circuit CH stops the intermittent operation.

  When the equalizing operation of both battery voltages is completed in this way, the switch S2 of the battery circuit 2 is turned on (turned on) automatically or manually, and the battery circuit 2 is connected to the battery circuit 1 in parallel. When the battery circuit 2 is connected in parallel to the battery circuit 1, the difference voltage between the batteries B1 and B2 is 0, so that the parallel connection can be executed safely without inrush current.

  In the fourth embodiment, as described above, the chopper circuit CH is intermittently controlled so as not to exceed the maximum allowable current Ip of the battery while monitoring the chopper current IL. The charging current to the lower battery is interrupted at a constant period T as shown in FIG. 11C, and its maximum value is limited to the maximum allowable current Ip of the battery. The ON period α in the intermittent cycle is narrowed when the pressure equalizing operation is started because the voltage difference ΔVB between the two batteries is large, and the voltage difference ΔVB between the two battery voltages decreases with the passage of the pressure equalizing operation time. Becomes wider.

  According to the fourth embodiment, the maximum value of the current during the voltage equalizing operation of the voltages of both batteries that are connected in parallel by the bidirectional chopper circuit 3 is limited to the set current value. For this reason, by setting the set current to, for example, the maximum allowable current Ip of the battery, the maximum value of the current flowing between both batteries during the pressure equalizing operation can be kept below the maximum allowable current Ip of the battery. Operation can be performed safely without damaging the battery.

1: Battery circuit constituting battery power supply 2: New battery circuit B1, B2: Battery S1, S2, S3: Switch 3: Bidirectional chopper circuit DB: Diode bridge circuit CH: Chopper circuit Q: Switching element L: Reactor D6 : Freewheeling diode

Claims (3)

When a new battery is connected in parallel to an existing battery constituting a battery power source or the like, the new battery is connected in parallel to the existing battery via a connection switch, and the connection switch is connected between the two batteries connected in parallel. Bypassing and connecting the bi-directional chopper circuit, opening the connection switch, the charge / discharge current flowing between the two batteries based on the voltage difference between the two batteries is controlled by the intermittent control of the bi-directional chopper circuit. In the battery parallel connection method of performing the pressure equalizing operation to equalize the voltage, then turning on the connection switch and connecting the batteries in parallel,
When performing the pressure equalization operation of the batteries by the intermittent control of the bidirectional chopper circuit, the maximum value of the charge / discharge current flowing between the batteries through the bidirectional chopper circuit is less than the maximum allowable current of the batteries. As described above, the bidirectional chopper circuit is intermittently controlled by setting the intermittent ratio to 1 at a predetermined intermittent period, and the current flowing through the bidirectional chopper circuit at the end of the ON period of the bidirectional chopper circuit A method for parallel connection of batteries, comprising: equalizing a voltage between the batteries by selecting a reactance of a reactor of the bidirectional chopper circuit so as to reach a maximum allowable current . 2. The parallel battery according to claim 1 , wherein a plurality (N) of the bidirectional chopper circuits are provided, and the intermittent control of each bidirectional chopper circuit is performed while being shifted by 1 / N of the intermittent period. Connection method. When a new battery is connected in parallel to an existing battery constituting a battery power source or the like, the new battery is connected in parallel to the existing battery via a connection switch, and the connection switch is connected between the two batteries connected in parallel. Bypassing and connecting the bi-directional chopper circuit, opening the connection switch, the charge / discharge current flowing between the two batteries based on the voltage difference between the two batteries is controlled by the intermittent control of the bi-directional chopper circuit. In the battery parallel connection method of performing the pressure equalizing operation to equalize the voltage, then turning on the connection switch and connecting the batteries in parallel,
When performing the pressure equalization operation of the batteries by the intermittent control of the bidirectional chopper circuit, the maximum value of the charge / discharge current flowing between the batteries through the bidirectional chopper circuit is less than the maximum allowable current of the batteries. So as to equalize the voltage between the batteries by controlling the intermittent ratio of the bidirectional chopper circuit,
The switching element of the bidirectional chopper circuit is turned on when the conduction current of the bidirectional chopper circuit becomes zero, and the switching element is turned on when the conduction current reaches the maximum allowable current of each battery. A battery parallel connection method characterized by performing intermittent control of the bidirectional chopper circuit by turning off the power.

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