JP2010063197A - Power supply unit and method for charging power storage means - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply unit having a simpler structure than a conventional one as well as capability of charging a plurality of power storage means connected in series and charging the power storage means connected in parallel while uniforming terminal voltage of each of the power storage means: and to provide a method for charging the power storage means. <P>SOLUTION: The power supply unit includes: a connection circuit 10 for connecting the plurality of power storage means; a circuit switching means for switching the power storage means between serial connection and parallel connection; a control means for controlling the circuit switching means. The circuit switching means includes: first switches SW1, SW2 for serially connecting the power storage means; and second switches SW3-SW6 for connecting the power storage means in parallel. The first switches SW1 and SW2 are a bidirectional switch, the second switches SW3-SW6 are a semiconductor element to be energized only in the single direction for charging the power storage means, and the control means connects the power storage means in series and connects the power storage means in parallel in discharging, regenerative charging and charging at a constant current. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power supply device and a method for charging power storage means, and in particular, a power supply device including a connection circuit for connecting a plurality of power storage means in series or in parallel, and power storage for charging a plurality of power storage means using the power supply device The present invention relates to a charging method of the means.

As a conventional power supply device, for example, a power supply device disclosed in Patent Document 1 is known.
As shown in FIG. 5, the power supply device includes a switching circuit 20 that switches the connection of the plurality of capacitor batteries 30 a and 30 b from a series connection to a parallel connection.
The changeover circuit 20 includes first to fifth changeover switches 21a to 21d, a first rectifier 23 comprising a combination of the first diode 22a and the first changeover switch 21a, and the reverse of the first diode 22a. The first switching means 25 is formed by connecting in parallel a second rectifying means 24 composed of a combination of the second diode 22b and the second changeover switch 21b.
The switching circuit 20 includes a third rectifier 26 composed of a combination of a third diode 22c and a third selector switch 21c, a fourth diode 22d and a fourth selector switch 21d opposite to the third diode 22c. And a second switching means 28 connected in parallel with a fourth rectifying means 27 comprising a combination of the above.
The switching circuit 20 connects a series circuit of the capacitor battery 30a and the first switching means 25 and a series circuit of the capacitor battery 30b and the second switching means 28 in parallel, and between the series connection points between the respective series circuits. The fifth switching switch 11e is connected to the first switching means 25 and the second switching means 28 in a complementary manner with respect to the fifth switching switch 11e.

In this power supply device, capacitor batteries 30a and 30b are connected in series at the time of charging, and charged by applying a voltage opposite to that at the time of discharging.
When predetermined energy is charged in the capacitor batteries 30a and 30b by charging in the series state, the capacitor batteries 30a and 30b are connected in parallel, and a voltage is applied to the series-connected circuits to charge them.
The terminal voltage of each capacitor battery 30a, 30b can be charged to a predetermined voltage by charging in parallel connection after charging in series connection.
JP 2000-175363 A

In the conventional power supply device, each switching means is a configuration in which two rectifiers that are energized in a single direction are combined in opposite directions. Each switching means requires two diodes and two switches.
In other words, this type of power supply device has a problem in that the power supply device is complicated and the manufacturing cost is high because there are many components of the switching circuit.
Further, in the case of discharge by parallel connection, each switching means is configured with a parallel connection switching circuit using rectification means (first rectification means, third rectification means) that energize only in the direction of discharge during parallel connection, for example, In addition, charging by regeneration from the external circuit (regenerative charging) is impossible.
However, since each switching means includes a rectifying means (second rectifying means, fourth rectifying means) that energizes only in the charging direction, regenerative charging is possible if switching to parallel connection so as to energize in the charging direction. Is possible.
However, in this case, it is necessary to switch the rectifying means each time switching between discharging and regenerative charging.
For this reason, there exists a problem which requires the discrimination circuit for discriminating discharge and regenerative charge, and the switching operation of a rectification means.

  The present invention has been made in view of the above problems, and an object of the present invention is to equalize the terminal voltage of each power storage means by connecting a plurality of power storage means in series and then charging them in parallel. In addition to being able to be charged, there is a provision of a power supply device having a simpler circuit configuration than the prior art and a method for charging the power storage means.

To achieve the above object, the present invention provides a connection circuit that electrically connects a plurality of power storage means, and a circuit switching means that is disposed in the connection circuit and switches the plurality of power storage means to a serial connection or a parallel connection. Control means for controlling the circuit switching means, the circuit switching means comprising: a first switch that connects the power storage means in series; and a second switch that connects the power storage means in parallel. The first switch is a bidirectional switch that energizes bidirectionally, the second switch is a semiconductor element that energizes only in one direction for charging the power storage means, and the control means is configured to discharge, Controlling the first switch during regenerative charging and constant current charging, connecting the power storage means in series, controlling the second switch during constant voltage charging, and connecting the power storage means in parallel. To do.
Note that the power storage means here may mean a rechargeable secondary battery and a capacitor, or may mean a battery module composed of a plurality of secondary batteries.

In the present invention, when the first switch is turned on and the second switch is turned off, the plurality of power storage means are connected in series, and conversely, when the first switch is turned off and the second switch is turned on, The power storage means are connected in parallel.
In a state where the power storage means are connected in series, the first switch can be energized bidirectionally, and is energized during discharging, regenerative charging, and constant current charging.
In a state where the power storage means are connected in parallel, the semiconductor element of the second switch can be energized only in one direction, and energizes during constant voltage charging.
Therefore, according to the present invention, the power storage means are connected in series and charged by constant current charging, and after constant current charging, the power storage means is switched from series connection to parallel connection and charged by constant voltage charging. The terminal voltage can be equalized.
Further, since the second switch is a semiconductor element that is energized only in one direction, a power supply device having a simpler circuit configuration than the conventional power supply device in which the second switch is a bidirectional switch can be provided.

In the present invention, in the power supply device described above, the semiconductor element may be a thyristor.
By using the semiconductor element of the second switch as a thyristor, the power supply apparatus can be made simpler and cheaper than a power supply apparatus using a semiconductor element that energizes the second switch bidirectionally.

According to the present invention, in the above power supply device, the power supply device further includes a voltage detection unit that detects a terminal voltage of each of the plurality of power storage units, and the voltage detection unit is configured such that any one of the plurality of power storage units has an upper limit voltage. The control means may control the circuit switching means to switch the power storage means from serial connection to parallel connection.
In this case, since the terminal voltage of each power storage means is detected and constant current charging is performed, it is possible to prevent the terminal voltage of each power storage means from exceeding the upper limit voltage in constant current charging and then charge by constant voltage charging. .

According to the present invention, the power supply apparatus further includes timer means for measuring a predetermined time from the start of constant current charging, and when the timer means measures the predetermined time, the control means controls the circuit switching means. Alternatively, switching from series connection to parallel connection may be performed.
In this case, when a predetermined time has elapsed from the start of constant current charging, the control means switches the power storage means from serial connection to parallel connection.
The predetermined time is preferably set to be equal to or less than the required time from the start of constant current charging until one of the terminal voltages reaches the upper limit voltage.
When the power supply device includes the timer unit and does not include the voltage detection unit, the upper limit voltage set in advance during the constant voltage charging can be charged without exceeding the terminal voltage of each power storage unit. Further, since it is not necessary to detect the terminal voltage of each power storage means, the voltage detection means is not necessary.
When the power supply device includes the voltage detection means together with the timer means, the voltage detection means functions before the timer means to prevent the upper limit voltage from being exceeded in charging when the remaining capacity of the storage means before charging is large. Can do.
Further, in charging when the remaining capacity of the power storage means before charging is small, the timer means can function before the voltage detection means to prevent excessive charging time.

Furthermore, the present invention is a method for charging power storage means using the power supply device according to claim 1, wherein the power storage means is connected in series by energizing the first switch, and is charged by constant current charging. Disconnecting the first switch after current charging to release the series connection of the storage means, connecting the storage means in parallel by energizing the second switch, and charging the storage means by constant voltage charging It is characterized by.
In the present invention, the power storage means are connected in series and charged by constant current charging, and after constant current charging, the power storage means is switched from serial connection to parallel connection and charged by constant voltage charging. Can be achieved.

  According to the present invention, after a plurality of power storage means are connected in series and charged, the power storage means can be connected in parallel and the terminal voltage of each power storage means can be equalized and charged. A power supply device having a circuit configuration and a method for charging a power storage unit can be provided.

Hereinafter, a power supply device according to an embodiment of the present invention will be described with reference to FIGS.
1 is a circuit diagram showing a configuration of a power supply device according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing a state in which power storage means in the power supply device are connected in series, and FIG. 3 is a power storage means of the power supply device. Is a circuit diagram showing a state in which is switched to parallel connection, and FIG. 4 is a flowchart showing a charging procedure used in the power supply device.
2 and 3 show only a portion to be energized in the power supply device for convenience.
The power supply device according to this embodiment will be described as a power supply device mounted on a vehicle.

As shown in FIG. 1, the power supply device includes a connection circuit 10 that electrically connects the three battery modules BT1 to BT3.
The battery modules BT <b> 1 to BT <b> 3 are configured by connecting three unit cells (secondary batteries) 11 in parallel.
In this embodiment, the battery modules BT1 to BT3 correspond to power storage means.
The cell 11 of this embodiment is a rechargeable lithium ion battery.
The terminal of the connection circuit 10 is connected to an electric motor (not shown) for driving as a load via an inverter (not shown) at the time of discharging, and connected to a power source (not shown) for charging at the time of charging. The
Terminals of the battery modules BT1 to BT3 are connected to a control circuit 12 installed separately from the connection circuit 10, and terminal voltages V1 to V3 of the battery modules BT1 to BT3 are detected by the control circuit 12.
The control circuit 12 has a function as a voltage detection means for detecting the terminal voltages V1 to V3, and also has a function as a timer means.

The power supply device includes switches SW1 to SW6 as circuit switching means for switching the battery modules BT1 to BT3 to series connection or parallel connection.
Switches SW1 and SW2 (hereinafter referred to as “first switches SW1 and SW2”) are bidirectional switches, and switches SW3 to SW6 (hereinafter referred to as “second switches SW3 to SW6”) are unidirectional switches. is there.
By turning on the first switches SW1 and SW2 and turning off the second switches SW3 to SW6, the battery modules BT1 to BT3 are connected in series as shown in FIG.
Conversely, by turning off the first switches SW1 and SW2 and turning on the second switches SW3 to SW6, the battery modules BT1 to BT3 are connected in parallel as shown in FIG.

The first switches SW1 and SW2 are switching circuits 13 that can be energized in both directions. In addition to a circuit (diode bridge) that combines a diode and a transistor, two reverse blocking IGBTs (RB-IGBT) are connected in opposite directions. A circuit connected in parallel, a circuit in which two reverse conducting IGBTs (RC-IGBT) are connected in series in opposite directions, or the like can be used.
The first switches SW1 and SW2 only have to have a function of energizing in both directions, and are not limited to semiconductor elements, and for example, a relay may be used as a mechanical switch.
Although not shown, the first switches SW1 and SW2 are connected to the control circuit 12, and are turned on / off under the control of the control circuit 12.
Therefore, the control circuit 12 has a function as a control means for controlling the first switches SW1 and SW2 in addition to the functions as the voltage detection means and the timer means.

The second switches SW <b> 3 to SW <b> 6 are semiconductor elements that can be energized only in one direction. In this embodiment, the thyristor 14 is used.
The second switches SW3 to SW6 are arranged in such a direction that they are not energized during discharging when the battery modules BT1 to BT3 are connected in parallel.
In other words, the second switches SW <b> 3 to SW <b> 6 are arranged in a direction to energize during charging.
The cathode of the thyristor 14 of the second switch SW3 is connected to the positive electrode of the battery module BT1, and the cathode of the thyristor 14 of the second switch SW4 is connected to the positive electrode of the battery module BT2.
The anode of the second switch SW5 is connected to the negative electrode of the battery module BT2, and the anode of the thyristor 14 of the second switch SW6 is connected to the negative electrode of the battery module BT3.
The gate is connected to the control circuit 12, and the gate is energized from the control circuit 12 and can be energized from the anode to the cathode.
That is, the control circuit 12 has a function as control means for controlling the second switches SW3 to SW6.

Next, discharge of the battery modules BT1 to BT3 using the power supply device according to the embodiment of the present invention will be described with reference to FIG.
In this embodiment, as a premise, in a non-operating state in which the key switch of the vehicle is off, the first switches SW1 and SW2 are on and the second switches SW3 to SW6 are off.
Therefore, as shown in FIG. 2, the battery modules BT1 to BT3 are connected in series.
In a state where the vehicle key switch is turned on and the vehicle is operating (for example, running), the control circuit 12 maintains the switches SW1 and SW2 on and the second switches SW3 to SW6 off, and the battery modules BT1 to BT3 It remains in series connection.
In a state where the battery modules BT1 to BT3 are connected in series, the voltage across the connection circuit 10 is increased by adding the terminal voltages V1 to V3 of the battery modules BT1 to BT3, and a large output suitable for driving the electric motor is obtained. can get.

By the way, although the electric discharge at the time of series connection drives an electric motor, the electric motor may be driven as a generator by braking or the like when the vehicle is running.
When the electric motor is driven as a generator, a counter electromotive force is generated in the electric motor.
In this case, due to the counter electromotive force of the electric motor, a regenerative current in the direction opposite to that in the case of discharging flows from the electric motor to the connection circuit 10 via the inverter.
Since the first switches SW1 and SW2 are bidirectional switches, the current due to regeneration passes through the connection circuit 10 and is charged to the battery modules BT1 to BT3 (charging during regeneration is referred to as “regenerative charging”). .
That is, in the case of series connection, the power supply device discharges the battery modules BT1 to BT3 or drives the regenerative current to the battery modules BT1 to BT3 by driving as an electric motor (powering) and driving as a generator (regeneration). Regenerative charging.

Next, charging of the battery modules BT1 to BT3 when the electric motor is stopped will be described with reference to FIGS.
While the electric motor is in the drive stop state, the key switch of the vehicle is kept on, the external charging power source and the power supply device are connected, and the battery modules BT1 to BT3 are charged.
FIG. 4 is a flowchart showing a processing procedure for charging the battery modules BT1 to BT3 using the power supply device.
First, constant current charging is performed in a state where the battery modules BT1 to BT3 are connected in series (see S1 in FIG. 4).
In the constant current charging, the charging current flowing through the connection circuit 10 is constant, and the terminal voltages V1 to V3 of the battery modules BT1 to BT3 are increased according to the charge amount.

During the constant current charging period, the control circuit 12 detects the terminal voltages of the battery modules BT1 to BT3.
The terminal voltages V1 to V3 of the battery modules BT1 to BT3 reach the upper limit voltage by constant current charging. For example, if the deterioration state differs for each of the battery modules BT1 to BT3, the terminal voltages V1 to BT3 reach the upper limit voltage Vup for each of the battery modules BT1 to BT3. The time until is different.
In this embodiment, if any one of the battery modules BT1 to BT3 by constant current charging has a battery module whose terminal voltage has reached the preset upper limit voltage Vup, the constant current charging is stopped (S2 in FIG. 4). , See S3).
When the constant current charging is stopped, the control circuit 12 turns off the first switches SW1 and SW2 to cancel the series connection of the battery modules BT1 to BT3 (see S4 in FIG. 4).

Next, the control circuit 12 turns on the second switches SW3 to SW6 to connect the battery modules BT1 to BT3 in parallel as shown in FIG. 3 (see S5 in FIG. 4).
Specifically, the control circuit 12 allows a current from the anode to the cathode of the thyristor 14 to flow through the thyristor 14 by passing a gate current of a predetermined value or more to turn on the second switches SW3 to SW6.
Then, the current is supplied again to the connection circuit 10, but the control circuit 12 controls the current that flows so that the terminal voltages V1 to V3 of the battery modules BT1 to BT3 do not exceed the upper limit voltage Vup.
Charging in parallel connection is constant voltage charging, and each battery module BT1 to BT3 is charged with a constant voltage (see S6 in FIG. 4).
Since the battery modules BT1 to BT3 are connected in parallel, even when the terminal voltages V1 to V3 of the battery modules BT1 to BT3 vary during charging in the state of being connected in series, the battery modules BT1 to BT3 The terminal voltages V1 to V3 are equalized.

In charging of each of the battery modules BT1 to BT3 by constant voltage charging, as shown in FIG. 4, when a preset constant voltage charging time has elapsed, the control circuit 12 ends charging and turns off the switches SW3 to SW6. The parallel connection is released (see S7 and S8 in FIG. 4).
The constant voltage charging time is a time for charging by constant voltage charging, and is a time set according to the type and performance of the battery modules BT1 to BT3.
The control circuit 12 has a function as timer means for measuring the constant voltage charging time.
After releasing the parallel connection, the control circuit 12 turns on the first switches SW1 and SW2 to connect the battery modules BT1 to BT3 in series (see S10 in FIG. 4).
When the battery modules BT1 to BT3 are connected in series, the charging process is terminated.

The power supply device according to this embodiment and the charging method using this power supply device have the following effects.
(1) Battery modules BT1 to BT3 are connected in series and charged by constant current charging. After constant current charging, the battery modules BT1 to BT3 are switched from serial connection to parallel connection and charged by constant voltage charging. It is possible to equalize the terminal voltages V1 to V3 of .about.BT3.
(2) A plurality of battery modules BT1 to BT3 are connected in series and charged by constant current charging. After constant current charging, these battery modules BT1 to BT3 are connected in parallel and charged by constant voltage charging. Discharging and regenerative charging during driving (powering or regeneration) are performed in a series connection state. Since there is no need for a discrimination circuit for discriminating between discharge and regenerative charge related to the operation of the electric motor, a switch for switching the circuit every time switching between discharge and regenerative charge, and its switching operation, the circuit configuration is simpler than before. A power supply apparatus can be provided.

(3) The thyristor 14 energized in a single direction is less expensive than a bidirectional switch energized in both directions. Therefore, by using the semiconductor elements of the second switches SW3 to SW6 as the thyristor 14, the power supply apparatus can be made simpler and less expensive than a power supply apparatus using a semiconductor element that energizes the second switch bidirectionally. it can.
(4) When performing constant-voltage charging after constant-current charging using a power supply device having a simpler circuit configuration than before, the terminal voltages V1 to V3 of the battery modules BT1 to BT3 are set to the preset upper limit voltage Vup. Appropriate charging without exceeding can be performed. This is particularly effective when the cells constituting the battery modules BT1 to BT3 are lithium ion batteries that are strictly required to prevent the upper limit voltage from being exceeded.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the gist of the invention.
In the above embodiment, the thyristor is used as the semiconductor element energized in one direction as the second switch, but a reverse blocking IGBT (RB-IGBT) having a function of energizing in one direction is used as the semiconductor element. May be. Alternatively, a diode and IGBT or MOSFET connected in series may be used.
In the above embodiment, the battery module is a combination of a plurality of rechargeable lithium ion batteries as a power storage means, but the power storage means is a rechargeable single battery other than a lithium ion battery (for example, a nickel cadmium battery, a nickel metal hydride battery, A battery module combining a lead battery or the like may be used. Alternatively, the unit cell itself may be used as the power storage means, and the capacitor may be used as the power storage means.

In the above embodiment, in charging in series connection, the control circuit detects the terminal voltage of each battery module as voltage detection means, and when any of the battery module terminal voltages reaches the upper limit voltage, the series connection is released. However, the present invention is not limited to this, and for example, in charging in series connection, the series connection may be canceled after a predetermined time has elapsed from the start of charging, and connected in parallel. In this case, it is desirable to use the timer function provided in the control circuit and determine the set time in consideration of the variation in the charging time of each battery module so that the voltage value after a predetermined time is equal to or lower than the upper limit voltage. What is necessary is just to preset the time according to the performance.
Further, the function as the voltage detecting means included in the control circuit and the function as the timer means may be used in combination. In this case, in the charging when the remaining capacity of the battery module before charging is large, the function as the voltage detecting means functions before the timer function, and in the charging when the remaining capacity of the battery module before charging is small. The control is set so that the timer means functions before the function as the voltage detecting means. Thereby, it is possible to prevent excessive charging time particularly in charging when the remaining capacity is small while preventing the upper limit voltage of the battery module from being exceeded.

In the above embodiment, the power supply device is mounted on the vehicle. However, the power supply device may be mounted on a mobile body other than the vehicle, or the power supply device may be provided in a facility that is not a mobile body. .
In the above embodiment, the number of the single cells 11 or the battery modules is not limited, although the number of the single cells 11 or the battery modules constituting the battery module is three.
In the above embodiment, the control circuit has all the functions of the control means, voltage detection means, and timer means, but the control means, voltage detection means, and timer means may be installed independently of each other.

It is a circuit diagram which shows the structure of the power supply device which concerns on embodiment of this invention. It is a circuit diagram which shows the state in which the connection circuit in a power supply device is connected in series. It is a circuit diagram which shows the state in which the connection circuit in a power supply device is connected in parallel. It is a flowchart which shows the procedure of the charging process of the battery module by a power supply device. It is a circuit diagram which shows the structure of the conventional power supply device.

Explanation of symbols

10 connection circuit 11 cell 12 control circuit 13 switching circuit 14 thyristor BT1, BT2, BT3 battery module SW1, SW2 first switch SW3, SW4, SW5, SW6 second switch V1, V2, V3 terminal voltage 20 for each battery module switching Circuits 21a, 21b, 21c, 21d Changeover switches 22a, 22b, 22c, 22d Diode 25 First switching means 28 Second switching means

Claims (5)

A connection circuit for electrically connecting a plurality of power storage means;
A power supply apparatus, comprising: a circuit switching unit disposed in the connection circuit; and switching the plurality of power storage units to a serial connection or a parallel connection; and a control unit for controlling the circuit switching unit.
The circuit switching means is
A first switch for connecting the power storage means in series;
A second switch for connecting the power storage means in parallel,
The first switch is a bidirectional switch that energizes bidirectionally;
The second switch is a semiconductor element that is energized only in one direction for charging the power storage means,
The control means includes
Controlling the first switch at the time of discharging, at the time of regenerative charging and at the time of constant current charging, and connecting the power storage means in series;
A power supply apparatus that controls the second switch during constant voltage charging and connects the power storage means in parallel.   The power supply apparatus according to claim 1, wherein the semiconductor element is a thyristor. Voltage detecting means for detecting a terminal voltage of each of the plurality of power storage means,
The voltage detection means, when the terminal voltage of any of the plurality of power storage means has reached an upper limit voltage,
The power supply apparatus according to claim 1, wherein the control unit controls a circuit switching unit to switch the power storage unit from a serial connection to a parallel connection. Timer means for measuring a predetermined time from the start of constant current charging,
4. The power supply device according to claim 1, wherein when the timer means measures the predetermined time, the control means controls the circuit switching means to switch from serial connection to parallel connection. . A method for charging power storage means using the power supply device according to claim 1,
The power storage means is connected in series by energizing the first switch,
Charge by constant current charge,
By disconnecting the first switch after constant current charging, the series connection of the power storage means is released,
The power storage means is connected in parallel by energizing the second switch,
A method for charging power storage means, comprising charging the power storage means by constant voltage charging.

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