WO2020059058A1

WO2020059058A1 - Storage battery device

Info

Publication number: WO2020059058A1
Application number: PCT/JP2018/034699
Authority: WO
Inventors: 黒田　和人; 関野　正宏; 弘樹松下; 英生山崎; クラレンスジョイヴィリアモアカトリコ
Original assignee: 株式会社東芝
Priority date: 2018-09-19
Filing date: 2018-09-19
Publication date: 2020-03-26

Abstract

A storage battery device according to an embodiment is mounted on a vehicle to supply power to an on-vehicle device and is provided with: a battery unit having a plurality of battery cells connected in series between a pair of first charging/discharging terminals; a DC/DC converter for boosting the voltage of the battery unit; and a control unit which, when the output voltage of the battery unit becomes less than or equal to a predetermined threshold voltage lower than a rated output voltage of the storage battery device, controls the boost ratio of the DC/DC converter to be constant. The storage battery device is therefore easy to handle and can supply high-voltage system power, while achieving a decrease in size.

Description

Storage battery device

The embodiment of the present invention relates to a storage battery device.

2. Description of the Related Art In recent years, in automobiles, in order to increase power consumption of electrical components and utilize regenerative energy, the power supply voltage in the vehicle, which has been generally used to 12 V until now, is supplied to in-vehicle equipment (auxiliary equipment), electrical components, and the like. Consideration has been given to voltage conversion (36 to 48 V). For example, when the rated voltage is set to 48 V, the output can be increased as compared with the existing 12 V system, and the current used can be reduced, so that the efficiency can be increased in some systems.

On the other hand, in order to utilize regenerative energy, the use of lithium-ion batteries as power storage elements that are small, large-capacity, and capable of withstanding repeated charging and discharging is expanding.

JP 2009-277647 A JP 2001-136735 A

By the way, as the power supply voltage becomes higher, the number of series of battery cells constituting a lithium ion battery is increased. However, simply increasing the number of series of battery cells is not easy for a lithium ion battery (battery pack). This leads to an increase in size.
In order to avoid this, it is conceivable to obtain a desired high voltage with a small number of battery cells connected in series using a DC / DC converter.

However, since the voltage of a battery cell varies greatly depending on the state of charge and discharge, the difference between the output voltage and the required high voltage is large, particularly when the battery cell has a configuration that can also be used as a low-voltage power supply. Therefore, the size of the coil used for the DC / DC converter becomes large, and there is a possibility that a mounting problem may occur in an application where the mountable place is limited like an automobile.

The present invention has been made in view of the above, and an object of the present invention is to provide a storage battery device that is easy to handle and can supply high-voltage power while reducing the size of the device.

The storage battery device of the embodiment is a storage battery device that is mounted on a vehicle and supplies power to in-vehicle devices, and includes a battery unit having a plurality of series-connected battery cells between a pair of first charge / discharge terminals, A DC / DC converter for boosting the voltage of the battery unit, and a step-up ratio of the DC / DC converter when the output voltage of the battery unit falls below a predetermined threshold voltage lower than the rated output voltage of the storage battery device. And a control unit for controlling.

FIG. 1 is a schematic block diagram of a storage battery system for a vehicle according to an embodiment. FIG. 2 is a schematic configuration block diagram of the storage battery device. FIG. 3 is an explanatory diagram when the charge / discharge current of the embodiment is zero. FIG. 4 is a processing flowchart when the storage battery device is charged and discharged.

Next, embodiments will be described in detail with reference to the drawings.
FIG. 1 is a schematic block diagram of a storage battery system for a vehicle according to an embodiment.
The vehicle storage battery system 10 functions as a generator (generator) 12G that can be driven by the engine 11 to generate power, or functions as a motor (motor) 12M that is supplied with electric power to assist (assist) driving the engine 11. Power device 12, a storage battery device 13 for supplying power to the vehicle-mounted device, a controller 14 that measures the state of charge (voltage, charging current, and temperature) of the storage battery device 13 and controls the storage battery device 13, and a storage battery device. And a load group 15 to which high-voltage power (for example, 48 V power) is supplied from the power supply 13.
In the above configuration, the power device 12 is included in the load group 15 when functioning as the electric motor 12M.

Here, the configuration of the storage battery device 13 will be described.
FIG. 2 is a schematic configuration block diagram of the storage battery device.
The storage battery device 13 includes a control unit 21 configured as a microprocessor unit (MPU) or the like that controls the entire storage battery device 13, a battery unit 23 in which a plurality of battery cells 22 are connected in series, and a state of the battery unit 23. (SOC, voltage, charging current, and temperature), and a monitoring circuit 24 that notifies the control circuit 21 of the monitoring result.

In the above configuration, the control unit 21 has a function of detecting the output voltage Vout.
As the battery cell 22, a lithium ion secondary battery or a nickel hydride secondary battery is preferable because of its excellent output characteristics. In addition, from the viewpoint of a high weight energy density, a lithium ion secondary battery is more preferable.

The storage battery device 13 has one end connected to the high potential side terminal of the battery unit 23, one end connected to the low potential side terminal of the battery unit 23, and the other end connected to the other end of the coil 25. A first transistor unit 26, a second transistor unit 27 having one end connected to the other end of the coil 25, and one end connected to the other end of the second transistor unit 27, and the other end connected to the low potential side of the battery unit 23. And a capacitor 28 connected to the terminal and the input / output terminal T2.

The storage battery device 13 further includes a third transistor unit 29 having one end connected to the other end of the second transistor unit 27 and the other end connected to the input / output terminal T1, and a connection point between the second transistor unit 27 and the capacitor. A current sensor 30 provided on a current path closer to the third transistor unit 29 than the CP and detecting the output current Iout; a first transistor unit 26, a second transistor unit 27, and a third transistor unit under the control of the control unit 21 And a gate driver 31 for driving the driving circuit 29.

In the above-described configuration, the first transistor unit 26 has an N-channel MOS having a source terminal S connected to the low potential side terminal of the battery unit 23, a drain terminal connected to the coil 25, and a gate terminal G connected to the gate driver 31. The transistor 26T includes a diode (parasitic diode) 26D whose anode terminal A is connected to the source terminal S of the N-channel MOS transistor 26T and whose cathode terminal K is connected to the drain terminal D of the N-channel MOS transistor 26T. .

The second transistor unit 27 has an N-channel MOS transistor having a source terminal S connected to a drain terminal D of an N-channel MOS transistor 26T, a drain terminal D connected to a capacitor 28, and a gate terminal G connected to a gate driver 31. The transistor 27T includes a diode (parasitic diode) 27D whose anode terminal A is connected to the source terminal S of the N-channel MOS transistor 27T and whose cathode terminal K is connected to the drain terminal D of the N-channel MOS transistor 27T. .

The third transistor unit 29 includes an N-channel MOS transistor 27T having a source terminal S connected to the input / output terminal T1, a drain terminal D connected to the capacitor 28, a gate terminal G connected to the gate driver 31, and an anode. A diode (parasitic diode) 29D whose terminal A is connected to the source terminal S of the N-channel MOS transistor 29T and whose cathode terminal K is connected to the drain terminal D of the N-channel MOS transistor 29T is provided.

In the above configuration, the coil 25, the first transistor unit 26, the second transistor unit 27, and the capacitor 28 constitute a DC / DC converter 35 configured as a step-up / step-down chopper circuit.

Here, when the DC / DC converter 35 functions as a boost chopper circuit that supplies power from the battery unit to the vehicle, the first transistor unit 26 effectively functions as a switch, and the second transistor unit 27 It effectively functions as the diode 27D.

When the DC / DC converter 35 functions as a step-down chopper circuit that charges the battery unit from the vehicle, the first transistor unit 26 effectively functions as a diode D26, and the second transistor unit 27 functions as a switch. It is functioning.
In addition, the third transistor unit 29 functions as a circuit breaker provided in the discharge current path when the battery unit 23 discharges.

Next, the operation of the embodiment will be described.
First, the principle of the present embodiment will be described.

In the present embodiment, when the output voltage Vout0 of the battery unit 23 corresponding to the SOC (State of Charge) of the battery unit 23 is lower than the first threshold voltage VTH1, the battery unit 23 is allowed to do so. The boosting is performed at a constant boosting ratio so as to be within the allowable output voltage. As a result, the size of the coil for functioning as the step-up / step-down chopper circuit can be suppressed as compared with the case where the effective output voltage of the battery unit 23 is made closer to the rated output voltage. The size of the storage battery device 13 can be reduced.

In the present embodiment, when the output voltage Vout0 of the battery unit 23 corresponding to the SOC of the battery unit 23 is equal to or higher than the first threshold voltage VTH1 and lower than the second threshold voltage VTH2 (> VTH1), The control is performed so that the storage battery device 13 exhibits the same behavior as a normal secondary battery that does not include the DC / DC converter 35. Thus, a load or a charging device external to the storage battery device 13 can perform control without performing any special control assuming that a normal secondary battery is connected as the storage battery device 13.

Further, in the present embodiment, when the output voltage Vout0 of the battery unit 23 corresponding to the SOC of the battery unit 23 is equal to or higher than the second threshold voltage VTH2, the operation of the DC / DC converter is not performed effectively. It is also possible to output the output voltage Vout0 of the battery unit 23 as it is. By adopting such a configuration, the storage battery device 13 naturally behaves as a normal secondary battery without the DC / DC converter 35 when viewed from the load external to the storage battery device 13 or the charging device. .

More specifically, the output voltage Vout0 of the battery unit 23 corresponding to the SOC of the battery unit 23 is represented by Expression (0).
Vout0 = VOFS + KSOC.SOC-KI.Iout (0)

Here, VOFS is a predetermined offset voltage (unit V), KSOC is a coefficient (constant value: unit V /%) corresponding to the SOC of the battery unit 23, SOC is SOC (unit%) of the battery unit 23, KI is a coefficient (constant value: unit Ω) that artificially represents the internal resistance of the battery unit 23, and Iout is the output current (unit A) of the storage battery device 13.

When the output voltage Vout0 of the battery unit 23 is lower than the first threshold voltage VTH1, the output voltage Vout of the storage battery device 13, that is, the output voltage of the DC / DC converter 35 satisfies the above-described condition. It is set according to equation (1).
Vout = KG · Vin (1)
Here, KG is a constant step-up ratio, and Vin is the voltage of the power actually output from the battery unit 23 to the DC / D converter 35.

When the output voltage Vout0 of the battery unit 23 corresponding to the SOC of the battery unit 23 is equal to or higher than the first threshold voltage VTH1 and lower than the second threshold voltage VTH2, the output voltage Vout of the storage battery device 13, that is, The output voltage of the DC / DC converter 35 is set according to the equation (2) so that the output voltage of the storage battery device 13 exhibits the same behavior as a normal storage battery in which the DC / DC converter 35 is not provided.
Vout = VOFS + KSOC.SOC-KI.Iout (2)

Further, when the output voltage Vout0 of the battery unit 23 corresponding to the SOC of the battery unit 23 is equal to or higher than the second threshold voltage VTH2, the output voltage of the storage battery unit 23 is set to the output voltage of the storage battery device 13, so that the equation (3) It becomes what is shown in.
Vout = Vin (3)
Note that this region does not exist when the charge end voltage of the battery unit 23 does not exceed the second threshold voltage VTH2.

FIG. 3 is an explanatory diagram when the charge / discharge current of the embodiment is zero.
More specifically, when the rated output voltage required for the storage battery device 13 is 48 V, the maximum allowable output voltage is 54 V, and the minimum allowable output voltage is 36 V, for example, as shown in FIG. Then, the first threshold voltage VTH1 = 42V and the second threshold voltage VTH2 = 48V.

Further, it is assumed that the discharge end voltage of the battery unit 23 is 18 V and the charge end voltage is 50 V.
Further, the boost ratio KG = 2, the offset voltage VOFS = 24 V, the coefficient KSOC = 0.24 V /%, and the coefficient KI = 0.01Ω.

In the case of this example, as shown in FIG. 2, the output voltage Vout0 of the battery unit 23 corresponding to the SOC is in a region where the first threshold voltage VTH1 is equal to or less than 42V, that is, when the voltage Vin of the battery unit 23 is 18 to 21V. Within the range, the output voltage Vout follows the equation (1), and thus becomes a voltage proportional to the voltage Vin within the range of Vout = 36 to 42V.

Also, the output voltage Vout0 of the battery unit 23 corresponding to the SOC exceeds the first threshold voltage VTH1 = 42V and is less than the second threshold voltage VTH2 = 48V, that is, within the range of the voltage Vin = 21 to 48V of the battery unit 23. , The output voltage Vout changes within the range of Vout = 42 to 48 V according to the equation (2), and apparently exhibits a voltage behavior such that the DC / DC converter 35 does not exist.

(4) When the output voltage Vout0 of the battery unit 23 corresponding to the SOC is equal to or higher than the second threshold voltage 48V, the output voltage Vout becomes equal to the output voltage Vout0 = Vin.

Next, an operation at the time of charging and discharging of the storage battery device 13 of the embodiment will be described.
FIG. 4 is a processing flowchart when the storage battery device is charged and discharged.
When the controller 14 starts supplying power to the load group 15, the control unit 21 of the storage battery device 13 changes the state (SOC, voltage Vin, charging current, and temperature) of the battery unit 23 notified by the monitoring circuit 24. Acquire (Step S11).
Next, the controller 14 determines whether a failure notification has been received from the monitoring circuit 24 (step S12).

If the failure notification has not been received in the determination in step S12 (step S12; No), the control unit 21 detects the output current Iout of the storage battery device 13 based on the output of the current sensor 30 (step S13). .
Subsequently, based on the SOC of the battery unit 23 and the output current Iout, the control unit 21 calculates the output voltage Vout0 of the battery unit 23 corresponding to the SOC of the battery unit 23 as shown in Expression (0) ( Step S14).
Vout0 = VOFS + KSOC.SOC-KI.Iout (0)

Subsequently, the control unit 21 first
Vout0 ≦ VTH1
Is determined (step S15).

In the determination of step S15,
Vout0 ≦ VTH1
Is satisfied (step S15; Yes), the control unit 21 detects the output voltage Vout and, as shown in the above equation (1),
Vout = KG · Vin (1)
Then, the first transistor unit 26, the second transistor unit 27, and the third transistor unit 29 are controlled via the gate driver 31 (step S16).

Specifically, the control unit 21 operates the DC / DC converter 35 as a step-down chopper circuit to charge the battery cell when Vout> Vout0, and activates the DC / DC converter 35 when Vout ≦ Vout0. The boost chopper circuit is controlled so as to operate in a direction to discharge the battery cells. As described above, the control unit 21 controls the DC / DC converter 35 so that the difference between Vout and Vout0 disappears, but controls the output current Iout within a range where the output current Iout falls within the allowable charge / discharge current.

That is, the control unit 21 controls the on-duty of the N-channel MOS transistor 26T of the first transistor unit 26 and the N-channel MOS transistor 27T of the transistor unit 27 so that the output voltage Vout = KG · Vin in accordance with the predetermined clock signal. Of on-duty control.

Further, the N-channel MOS transistor 27T of the transistor unit 27 is kept open (off state) while the N-channel MOS transistor 26T is on, and the N-channel MOS transistor 27T of the transistor unit 27 is kept off during the off period of the N-channel MOS transistor 26T. Set to the closed state (ON state).

As a result, control is performed so that the output voltage Vout = KG · Vin.
Also, in the determination of step S15,
Vout0> VTH1
Is satisfied (step S15; No), the control unit 21
VTH1 <Vout0 ≦ VTH2
Is determined (step S17).

In the determination of step S17,
VTH1 <Vout0 ≦ VTH2
Is satisfied (step S17; Yes), the control unit 21 detects the output voltage Vout and, as shown in the above equation (2),
Vout = VOFS + KSOC.SOC-KI.Iout (2)
Then, the first transistor unit 26, the second transistor unit 27, and the third transistor unit 29 are controlled via the gate driver 31 (step S18).

Specifically, the control unit 21 operates the DC / DC converter 35 as a step-down chopper circuit to charge the battery cell when Vout> Vout0, and activates the DC / DC converter 35 when Vout ≦ Vout0. The boost chopper circuit is controlled so as to operate in a direction to discharge the battery cells.

That is, the control unit 21 performs opening / closing control (on / off control) of the N-channel MOS transistor 26T of the first transistor unit 26 and the N-channel MOS transistor 27T of the transistor unit 27 according to a predetermined clock signal.
Output voltage Vout = VOFS + KSOC.SOC-KI.Iout
Is controlled so that

結果 As a result, from the viewpoint of the load group 15 on the vehicle side, power is supplied according to the behavior accompanying the SOC change of the battery unit 23.

In step S17 determination,
VTH1 <Vout0 ≦ VTH2
If not (step S17; No), ie,
VTH2 <Vout0
(Step S17; No), the control unit 21 effectively stops the operation of the step-up / step-down chopper circuit (through the step-up / step-down chopper circuit) and reduces the power of the battery unit 23 to the voltage of the battery unit 23. Output as Vin. In other words, the N-channel MOS transistor 26T of the first transistor unit 26 is kept open (off state) and the N-channel MOS transistor 27T of the second transistor unit 27 is kept closed (on state) via the gate driver 31. , The output voltage Vout, as shown in the above equation (3),
Vout = Vin (3)
(Step S19).

On the other hand, when the failure notification is received in the determination in step S12, the control unit 21 requests the vehicle to permit the stop of the storage battery device through communication (step S20).
Subsequently, the control unit 21 determines whether a stop permission has been received from the vehicle (step S21).

If it is determined in step S21 that the stop permission has not yet been received from the vehicle, the process returns to step S20, and the above-described process is repeated.
If it is determined in step S21 that a stop permission has been received from the vehicle (step S21; Yes), the control unit 21 stops driving the

transistor units

26, 27, and 29 and ends the process.

As described above, when power is supplied to the storage battery device 13 of the embodiment, when Vout0 ≦ VTH1, power is supplied at a constant boosting ratio. The size of the device 13 can be reduced.

When VTH1 <Vout0 ≦ VTH2, the behavior of the storage battery device 13 is simulated as a simple storage battery device without a step-up / step-down chopper circuit. Therefore, the load group 15 can be viewed as a mere storage battery device having no control function, and there is no need to perform special control on the load group 15 side.

Further, when VTH2 <Vout0, the step-up / step-down chopper circuit is effectively stopped and the power of the battery unit 23 constituting the storage battery device 13 is supplied as it is, so that the step-up / step-down chopper circuit is always operated. Power consumption can be reduced as compared with the case where the power is stored, and the capacity of the storage battery device 13 effectively increases.

As described above, according to the present embodiment, it is possible to provide a storage battery device that is easy to handle and can supply high-voltage power while reducing the size of the device.

The program executed by the storage battery device of the present embodiment can be read by a computer such as a semiconductor storage device such as a CD-ROM, a DVD (Digital Versatile Disk), and a USB memory in an installable or executable file. It is provided by being recorded on a recording medium.

Further, the program executed by (the control unit of) the storage battery device of the present embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. . Further, the program executed by (the control unit of) the storage battery device of the present embodiment may be provided or distributed via a network such as the Internet.

The program executed by (the control unit of) the storage battery device of the present embodiment may be configured to be provided by being incorporated in a ROM or the like in advance.

Although some embodiments of the present invention have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. These new embodiments can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the invention described in the claims and equivalents thereof.

Claims

A storage battery device that is mounted on a vehicle and supplies power to in-vehicle devices,
A battery unit having a plurality of battery cells connected in series between a pair of first charge / discharge terminals;
A DC / DC converter for increasing the voltage of the battery unit;
A control unit that controls a step-up ratio of the DC / DC converter to be constant when an output voltage of the battery unit is equal to or lower than a predetermined threshold voltage lower than a rated output voltage of the storage battery device;
A storage battery device comprising:
Of the discharge-side current path and the charge-side current path of the battery unit, a breaker is provided only in the discharge-side current path,
The storage battery device according to claim 1.
An output voltage detection unit that detects an output voltage of the DC / DC converter;
An output current detection unit that detects an output current of the DC / DC converter,
The control unit varies the output voltage of the DC / DC converter in proportion to the output current, reduces the output voltage of the DC / DC converter when discharging the battery unit, and reduces the output voltage when charging the battery unit. Increasing the output voltage of the DC / DC converter;
The storage battery device according to claim 1.
A charging rate detection unit that detects a charging rate in the battery unit,
The control unit varies the output voltage of the DC / DC converter in proportion to the charging rate, reduces the output voltage of the DC / DC converter when discharging the battery unit, and reduces the output voltage when charging the battery unit. Increasing the output voltage of the DC / DC converter;
The storage battery device according to any one of claims 1 to 3.
The control unit, when the voltage becomes equal to or higher than a predetermined second threshold voltage higher than the threshold voltage, effectively stops the operation of the DC / DC converter, and outputs the output voltage of the battery unit to the DC / DC converter. Output voltage,
The storage battery device according to claim 1.