JP2020136163A - Power supply unit - Google Patents

Abstract

To provide a power supply unit that can reduce performance degradation at low temperatures while avoiding rapid discharge of a large current.SOLUTION: A power supply unit 1 is used as a drive source for a starter generator 3 and includes a lithium ion battery 2 and a capacitor 11 connected in parallel with the battery 2. The capacitor 11 is attached to the battery 2 via a heat conductive sheet 22. The power supply unit 1 is provided with a first circuit 15 including a FET 12 and a resistor 13 and to which the capacitor 11 is connected, and a second circuit 16 that directly connects the battery 2 and the starter generator 3 side and is opened/closed by a contactor 17. When an engine starts, electric power is supplied from the capacitor 11 while suppressing the amount of current from the battery 2 by the resistor 13. When power is supplied to the capacitor, the heat of the capacitor 11 is used to heat the battery 2.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power supply unit that supplies electric power to a motor or the like, and more particularly to a technique that is effective when applied to a power supply unit that uses a lithium ion battery.

Conventionally, a secondary battery (lithium ion battery) using lithium ion has been used as a power supply source for hybrid vehicles and electric vehicles because of its high energy density, small size, light weight, and large current. ..

JP-A-2018-73535 Japanese Unexamined Patent Publication No. 2013-214663

However, in a system using a lithium ion battery, there is a problem that the life of the battery is shortened if the mode in which a large current is passed from the lithium ion battery is repeatedly performed. Further, the lithium ion battery has a characteristic that the function deteriorates at a low temperature, and there is also a problem that the amount of current that can be taken out from the battery becomes small at a low temperature.

On the other hand, in an automobile, for example, it is necessary to pass a large current through the starter motor when starting the engine. For this reason, when a lithium-ion battery is used in an automobile, the engine is repeatedly started in a hybrid vehicle or an idling stop vehicle, which may affect the battery life. In addition, since automobiles are used even in extremely cold regions such as -30 ° C, starting an engine at low temperatures is also an issue.

For this reason, solutions such as attaching a heater to the battery or separately providing a starter motor operated by a lead storage battery and using this motor at low temperatures have been proposed. However, these solutions also have problems such as an increase in the number of parts, an increase in weight, and an in-vehicle layout, and it is difficult to say that they are definitive. In particular, when a starter generator (ISG: Integrated starter generator) that also serves as a generator is used as the engine starter, if a starter motor is provided separately, the motor driver cannot be placed at the starter position, which is a problem in terms of layout. was there.

An object of the present invention is to provide a power supply unit capable of reducing performance deterioration at low temperatures while avoiding abrupt discharge of a large current.

The power supply unit of the present invention is a power supply unit connected to an electric driven device, and is arranged in the vicinity of a battery for supplying electric power to the driven device and the battery, and the battery and the battery are arranged on a circuit. It is characterized by having a capacitor connected in parallel with the battery between the driven devices.

In the present invention, by arranging the capacitor in parallel with the battery, electric power can be supplied from the capacitor when a large current is required, such as when the driven device is started. As a result, the large current output from the battery can be suppressed, and the life of the battery can be extended. Further, by arranging the capacitor in the vicinity of the battery, the battery can be heated by utilizing the heat generated by the capacitor, such as when power is supplied from the capacitor. This makes it possible to quickly make the battery usable at low temperatures.

In the power supply unit, the capacitor may be attached to the battery via a heat conductive member. As a result, the heat generated from the capacitor can be efficiently transferred to the battery.

Further, when the battery is formed in a rectangular parallelepiped shape and has a terminal electrically connected to the driven device on one surface thereof, the capacitor is attached to the surface of the battery where the terminal does not exist. You can do it. In this case, when the terminal is arranged on the upper surface of the battery, the capacitor may be arranged on the side surface of the battery.

Further, when the battery is formed in a rectangular parallelepiped shape and has a terminal electrically connected to the driven device on one surface thereof, the capacitor is placed on the surface of the battery where the terminal is present. It may be installed avoiding the terminals.

In addition, the heat conductive member may be provided so as to cover the capacitor. As a result, the heat of the capacitor can be used without waste to heat the battery.

On the other hand, a resistance element and a switching element may be provided between the battery and the capacitor. In this case, the power supply unit is provided with the resistance element and the switching element, and the first circuit to which the capacitor is connected is provided in parallel with the first circuit, and the battery and the driven device are directly connected to each other. A second circuit to be connected and a contactor provided in the second circuit and opening and closing the second circuit may be provided.

Further, the battery may be a lithium ion battery, and the driven device may be a starter generator that starts an engine of an automobile and is driven by the engine to generate electricity.

According to the power supply unit of the present invention, since the capacitor is arranged in parallel with the battery that supplies electric power to the electric driven device, the electric power is supplied from the capacitor when a large current is required such as when the driven device is started. Can be supplied. As a result, the large current output from the battery can be suppressed, and the battery life can be extended. Further, since the capacitor is arranged in the vicinity of the battery, the battery can be heated by utilizing the heat generated by the capacitor, and the battery can be quickly used at a low temperature.

It is explanatory drawing which shows the structure of the ISG drive circuit using the power supply unit which is one Embodiment of this invention. It is explanatory drawing which shows the mounting structure of a capacitor. It is explanatory drawing which shows the example which attached the capacitor to the upper surface of a battery. It is explanatory drawing which shows the example which attached the capacitor to the lower surface of a battery. It is explanatory drawing which shows the example which covered the capacitor with the heat conduction sheet.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram showing a configuration of an ISG drive circuit using a power supply unit according to an embodiment of the present invention. The power supply unit 1 of FIG. 1 uses a battery 2 of a lithium-ion battery as a power supply source, and has a starter generator (driven device) 3 using an SR motor (Switched reluctance motor) via a driver 4. Supply power. The power supply unit 1 according to the present invention has a capacitor 11 in addition to the battery 2. When the engine is started, power is first supplied from the capacitor 11, and the battery 2 is warmed by utilizing the heat generated when the capacitor is discharged to be used at low temperature. Suppresses the deterioration of battery performance in.

The driver 4 has a three-phase (U, V, W) independent bridge circuit 5 using FETs. A switch unit 6 using an FET is arranged in front of the bridge circuit 5. The bridge circuit 5 and the switch unit 6 are controlled by an ECU (engine control unit: engine control unit) 7. When the ignition switch 8 is turned on, the ECU 7 sequentially excites the coils 9 of each phase by the electric power of the battery 2 to drive the starter generator 3. While the starter generator 3 functions as an engine starter, it also functions as a generator (generator) after the engine is started.

The power supply unit 1 is provided with a large-capacity capacitor 11. As shown in FIG. 1, the capacitor 11 is connected between the battery 2 and the driver 4 in parallel with the battery 2 on the circuit. A switch unit 14 having a FET (switching element) 12 and a resistor (resistor element) 13 is arranged between the capacitor 11 and the battery 2. The FET 12 and the resistor 13 are provided in series on the first circuit 15 that connects the battery 2 and the driver 4. The capacitor 11 is connected to the subsequent stage (driver 4 side) of the switch unit 14 of the first circuit 15. The FET 12 is controlled by the ECU 7.

Further, the power supply unit 1 is provided with a second circuit 16 that connects the battery 2 and the driver 4 by a route different from that of the first circuit 15. The second circuit 16 is provided in parallel with the first circuit 15, and includes a contactor 17 that opens and closes the first circuit 15. The contactor 17 is also controlled by the ECU 7, and by turning on the contactor 17, the electric power of the battery 2 can be supplied to the driver 4 side without going through the FET 12 or the resistor 13.

On the other hand, in the power supply unit 1 according to the present invention, the capacitor 11 is arranged in the vicinity of the battery 2, and the heat of the capacitor 11 is transferred to the battery 2. FIG. 2 is an explanatory view showing a mounting structure of the capacitor 11. As shown in FIG. 2, the battery 2 is formed in a rectangular parallelepiped shape, and the capacitor 11 is attached to the side surface 21 of the battery 2 via a heat conductive sheet (heat conductive member) 22. An electric double layer capacitor is used for the capacitor 11, and a plurality of electric double layer capacitors are connected in series in consideration of withstand voltage and are fixed to the side surface 21. The capacitor 11 and the battery 2 are in contact with each other with the heat conductive sheet 22 interposed therebetween, and the heat generated by the capacitor 11 is conducted to the battery 2 through the heat conductive sheet 22.

Further, the upper surface 23 of the battery 2 is provided with a terminal 24 that is electrically connected to the driver 4. In the power supply unit 1, the capacitor 11 is attached to the side surface 21 of the battery 2 in which the terminal 24 does not exist. In this case, it is easier to arrange the capacitor 11 on the side surface 21 without the terminal 24 than on the upper surface 23 with the terminal 24. That is, the side surface 21 in which the terminal 24 does not exist has better layout and a higher degree of freedom in design. Further, the battery 2 is equipped with a temperature sensor 18 for detecting the battery temperature. The temperature of the battery 2 is detected by the temperature sensor 18, and the detected value is sent to the ECU 7.

The ECU 7 includes a driver control unit 31 that controls the bridge circuit 5 and the switch unit 6 of the driver 4, a power supply control unit 32 that controls the FET 12 and the contactor 17 of the power supply unit 1, and a battery 2 based on the detected values from the temperature sensor 18. A battery temperature acquisition unit 33 for grasping the temperature of the battery is provided. The driver control unit 31 controls the FETs of the bridge circuit 5 and the switch unit 6 in accordance with the ON / OFF of the ignition switch 8, and appropriately supplies power to the coils 9 of each phase. The power supply control unit 32 also controls the FET 12 when the ignition switch 8 is turned on and off, and turns on the contactor 17 as necessary while referring to the battery temperature obtained by the battery temperature acquisition unit 33.

In the ISG drive circuit using such a power supply unit 1, the starter generator 3 is driven as follows. Here, first, when the ignition switch 8 is turned on, the ECU 7 turns on the switch unit 6 by the driver control unit 31. When the switch unit 6 is turned on, the electric charge stored in the capacitor 11 of the power supply unit 1 flows into the driver 4. Along with this, the driver control unit 31 appropriately turns on the FET in the bridge circuit 5 to excite the coil 9. At that time, since a large current is supplied from the capacitor 11 to the driver 4, the starter generator 3 is driven by a large current even at a low temperature. Therefore, the engine can be started smoothly even in the cold starting state where the outside air temperature is low.

Further, when the ignition switch is turned on, the ECU 7 turns on the FET 12 by the power supply control unit 32. When the FET 12 is turned on, a current is supplied from the battery 2 to the driver 4 side, and when the voltage of the capacitor 11 drops due to discharge, the capacitor 11 is charged by the battery 2. At this time, in the power supply unit 1, the amount of current flowing through the first circuit 15 is suppressed by the resistor 13, and it is possible to prevent a large current from being suddenly taken out from the battery 2. Therefore, it is possible to suppress the output of a large current at the time of starting, and even in a hybrid vehicle or an idling stop vehicle, the large current is not repeatedly passed from the battery 2, and the life of the lithium ion battery can be extended. In addition, the resistor 13 also suppresses the charging current when the starter generator 3 is used as a generator, and as a result, it is possible to avoid repeated charging and discharging of the battery 2 due to a sudden large current, and the battery life is extended. It is planned.

On the other hand, when a large current is output from the capacitor 11 when the engine is started, the capacitor 11 generates heat accordingly. In the power supply unit 1, as shown in FIG. 2, the capacitor 11 is attached in the vicinity of the battery 2, and the heat generated by the capacitor 11 is efficiently transferred to the battery 2 via the heat conductive sheet 22. That is, the battery 2 is heated by the heat generated by the capacitor 11. As described above, the performance of lithium-ion batteries deteriorates at low temperatures, and the supply of a large current when the engine is started has become an issue. In this respect, the power supply unit 1 supplies a large current at the time of starting by the capacitor 11, and heats the battery 2 by utilizing the heat generated by the capacitor 11. As a result, the battery temperature can be raised, and the battery 2 can be quickly put into a usable state at a low temperature. It should be noted that heat generation during capacitor charging can also be used.

Further, in the power supply unit 1, the temperature of the battery 2 is monitored by the temperature sensor 18. As described above, when the engine is started, power is supplied from the capacitor 11 while suppressing the amount of current from the battery 2 by the resistor 13. On the other hand, there are cases where it is necessary to supply power to the driver 4 side quickly, such as when the engine must be started in a hurry. In that case, after the power is supplied from the capacitor 11, the current suppressed by the resistor 13 may not be able to meet the required power supply amount. Therefore, the power supply unit 1 is provided with a second circuit 16 capable of directly supplying power from the battery 2 to the driver 4 side without passing through the resistor 13, and when rapid power supply is required, the ECU 7 powers the power supply. The contactor 17 is turned on by the control unit 32.

However, since a large current is supplied from the battery 2 when the contactor 17 is turned on, this battery-driver direct connection control is performed only when the temperature is not low (the temperature of the battery 2 is approximately 0 ° C. or higher). That is, the ECU 7 refers to the temperature of the battery 2 acquired by the battery temperature acquisition unit 33, and turns on the contactor 17 as necessary only when it is equal to or higher than a predetermined threshold value (here, 0 ° C.), and the battery 2 and the driver. Directly connected to 4. As a result, electric power is supplied to the driver 4 from the battery 2 without suppressing the amount of current, and the necessary electric power is promptly provided to the driver 4 side.

As described above, in the power supply unit 1 of the present invention, when the engine is started, power is supplied from the capacitor 11 while suppressing the amount of current from the battery 2 by the resistor 13. As a result, when the engine is started, the starter generator 3 is driven by a large current from the capacitor 11, and the engine can be started smoothly even in the cold state. Further, since the large current output from the battery 2 at the time of starting the engine can be suppressed, the battery life can be extended.

Further, the power supply unit 1 is arranged in the vicinity of the battery 2 so that the capacitor 11 can be used as a heating means, and when the capacitor is fed, the heat generated by the capacitor 11 is used to heat the battery 2. As a result, the battery 2 can be quickly used at a low temperature, the usage efficiency of the battery can be improved, and the range of use of the lithium ion battery can be expanded. In addition, the power supply unit 1 is provided with a second circuit 16 that connects the battery 2 and the driver 4 side without passing through a resistor 13, and while monitoring the battery temperature, the contactor 17 provides the second circuit 16 as needed. Open and close. As a result, when it is necessary to increase the amount of power supplied to the driver 4 except when the temperature is low, the necessary power is quickly provided to the driver 4.

It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist thereof.
For example, in the above-described embodiment, the example in which the capacitor 11 is attached to the side surface 21 of the battery 2 is shown, but in addition to the side surface 21 as shown in FIG. 2, the upper surface 23 (FIG. 3) and the lower surface 25 (FIG. 4) are shown. It is also possible to attach it to. In that case, the capacitor 11 on the upper surface 23 is arranged so as to avoid the terminal 24. Further, when the capacitor 11 is attached to the lower surface 25, the heat is easily transferred upward and the heat is easily trapped in the internal space of the pedestal 26, so that the heat of the capacitor 11 can be efficiently used. The location of the terminal 24 is not limited to the upper surface 23, and may be arranged on the side surface 21 or the lower surface 25. In that case, the relationship between the terminal 24 and the capacitor 11 is the same as described above, that is, the capacitor is placed on the surface without the terminal 24. While it is advantageous in terms of layout to arrange the 11th, when the capacitor 11 is provided on the surface where the terminal 24 is located, the terminal 24 is avoided. Further, the capacitors 11 can be distributed and arranged on a plurality of surfaces of the battery 2, whereby the battery 2 can be heated from the plurality of surfaces.

In addition, the capacitor 11 may be arranged so as to wrap the capacitor 11 with the heat conductive sheet 22 as shown in FIG. 5, instead of being exposed to the outside as shown in FIG. By covering the side surface of the capacitor 11 with the heat conductive sheet 22 in this way, the heat of the capacitor 11 can be utilized without waste to heat the battery 2. Further, the heat conductive sheet 22 may be provided not only on the arrangement surface of the capacitor 11 but also on a plurality of surfaces such as the other surface of the battery 2 and the entire surface of the battery, whereby the heat of the capacitor 11 is efficiently diffused to the battery 2. It becomes possible to grant.

In the above-described embodiment, an example in which the power supply unit of the present invention is used as a power source for a starter motor of an automobile engine is shown, but the application is not limited to this, and for example, an electric industrial device is driven. It can also be used as a power source for the motor.

1 Power supply unit 2 Battery 3 Starter generator 4 Driver 5 Bridge circuit 6 Switch part 7 ECU
8 Ignition switch 9 Coil 11 Capacitor 12 FET
13 Resistance 14 Switch unit 15 1st circuit 16 2nd circuit 17 Contactor 18 Temperature sensor 21 Side 22 Heat conduction sheet 23 Top 24 Terminal 25 Bottom 26 Pedestal 31 Driver control 32 Power control 33 Battery temperature acquisition

Claims (10)

A power supply unit connected to an electric driven device,
A battery that supplies power to the driven device and
A power supply unit arranged in the vicinity of the battery and having a capacitor connected in parallel with the battery between the battery and the driven device on a circuit. In the power supply unit according to claim 1,
The capacitor is a power supply unit that is attached to the battery via a heat conductive member. In the power supply unit according to claim 1 or 2.
The battery is formed in a rectangular parallelepiped shape, and has terminals on one side thereof that are electrically connected to the driven device.
The capacitor is a power supply unit that is mounted on a surface of the battery where the terminals do not exist. In the power supply unit according to claim 3,
The terminals are located on the top surface of the battery.
The power supply unit is characterized in that the capacitor is arranged on the side surface of the battery. In the power supply unit according to claim 1 or 2.
The battery is formed in a rectangular parallelepiped shape, and has terminals on one side thereof that are electrically connected to the driven device.
The capacitor is a power supply unit characterized in that it is mounted on a surface of the battery where the terminals are present, avoiding the terminals. In the power supply unit according to any one of claims 1 to 5.
The power supply unit is characterized in that the heat conductive member is provided by covering the capacitor. In the power supply unit according to any one of claims 1 to 6.
A power supply unit characterized in that a resistance element and a switching element are provided between the battery and the capacitor. In the power supply unit according to any one of claims 7.
A first circuit having the resistance element and the switching element and to which the capacitor is connected,
A second circuit provided in parallel with the first circuit and directly connecting the battery and the driven device,
A power supply unit provided in the second circuit and having a contactor for opening and closing the second circuit. In the power supply unit according to any one of claims 1 to 8.
A power supply unit characterized in that the battery is a lithium ion battery. In the power supply unit according to any one of claims 1 to 8.
The driven device is a power supply unit, which is a starter generator that starts an automobile engine and is driven by the engine to generate electric power.

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