JP7426273B2 - Step-up/step-up device and step-up/down method - Google Patents

Description

The present invention relates to a voltage raising/lowering device and a voltage raising/lowering method.

In general, a DC/DC converter that steps up or down a voltage has advantages such as high voltage transmission efficiency, but has disadvantages such as high cost. For this reason, there is a power supply device in which the function of the DC-DC converter is replaced by a capacitor and an H-bridge circuit (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2016-144339

However, in the conventional technology, when boosting or buckling the voltage, multiple switching elements provided in the H-bridge circuit must be appropriately controlled, which requires complicated control, so there is room for improvement. .

The present invention has been made in view of the above, and an object of the present invention is to provide a voltage step-up/down device and a voltage step-up/down method that can perform voltage step-up/down operations with simple control.

In order to solve the above-mentioned problems and achieve the objective, a buck-boost device according to an embodiment includes a plurality of capacitors and a plurality of switches. The plurality of capacitors are provided between a first battery and a second battery having a lower rated voltage than the first battery, one end is connected to the first battery, and each capacitor is connected in parallel to the second battery. Connecting. The plurality of switches are provided for each of the plurality of capacitors, and switch the connection state with the adjacent capacitors.

According to the present invention, voltage step-up and step-down operations can be performed with easy control.

FIG. 1 is a schematic diagram showing a configuration example of a power supply system. FIG. 2 is a diagram illustrating an example of a boosting operation by a capacitor section. FIG. 3 is a diagram illustrating an example of a boosting operation by a capacitor section. FIG. 4 is a diagram illustrating an example of a step-down operation by the capacitor section. FIG. 5 is a diagram illustrating an example of a step-down operation by a capacitor section. FIG. 6 is a schematic diagram of the capacitor section during boosting operation. FIG. 7 is a schematic diagram of the capacitor section during voltage step-down operation. FIG. 8 is a flowchart showing the processing procedure executed by the voltage elevating and lowering device. FIG. 9 is a flowchart showing the processing procedure executed by the voltage elevating and lowering device.

Embodiments of a voltage step-up/down device and a voltage step-up/down method according to the present invention will be described in detail below with reference to the drawings. Note that the present invention is not limited to this example.

First, a configuration example of a power supply system including a step-up/down device according to an embodiment will be described with reference to FIG. FIG. 1 is a schematic diagram showing a configuration example of a power supply system. In addition, below, the case where the power supply system 100 is mounted in vehicles, such as an electric vehicle, is mentioned as an example and demonstrated.

As shown in FIG. 1, the power supply system 100 includes a step-up/down device 1, an engine 10, a motor generator (MG) 11, a load 12, a main battery 20, and an auxiliary battery 40.

The engine 10 functions as a power generation source for driving the vehicle, and transmits rotational energy generated by the engine 10 to a tire shaft (not shown). The MG 11 functions as an electric motor that assists in driving the engine 10 of the vehicle when it is started or when the vehicle is running, and as a rotating electric machine that generates power using regenerated energy generated when the vehicle decelerates.

The load 12 is a variety of auxiliary machines that operate with power supplied from the auxiliary battery 40 or each of the capacitors C1 to C4, and includes a safety-related auxiliary machine and a comfort-related auxiliary machine. Further, the safety auxiliary equipment is, for example, a brake ECU. The comfort system auxiliary equipment is, for example, an A/V (audio/video) device.

The main battery 20 is, for example, a secondary battery composed of LiB (lithium-ion rechargeable battery), and has a rated voltage of 48V. Further, the main battery 20 is connected to the MG 11 via a latch relay Rc, and further connected to the capacitor section 30 via a first relay R1.

The auxiliary battery 40 is, for example, a secondary battery composed of a lead battery, and has a rated voltage of 12V. Auxiliary battery 40 is connected to capacitor section 30 via second relay R2. More specifically, capacitors C1 to C4 are connected in parallel to auxiliary battery 40. Note that the main battery 20 is an example of a first battery, and the auxiliary battery 40 is an example of a second battery.

The step-up/down device 1 includes a capacitor section 30 and a control IC 50. The capacitor section 30 is provided between the main battery 20 and the auxiliary battery 40, and functions as a power converter that increases and decreases the voltage. That is, in the embodiment, the capacitor unit 30 replaces the function of the DC/DC converter.

As shown in FIG. 1, the capacitor section 30 includes a plurality of capacitors C1 to C4 connected in parallel and a plurality of switches SW. Adjacent capacitors of the plurality of capacitors C1 to C4 are connected to each other via switches SW.

Further, as shown in FIG. 1, the switches SW installed in each of the capacitors C1 to C3 can switch the connection destination of each of the capacitors C1 to C3 between the 12V first ground G1 or the adjacent capacitors C2 to C4. can.

Note that the relay R installed on the capacitor C4 is connected to the second ground of 48V since there is no capacitor on the downstream side. Further, one end (capacitor C1) of the capacitor section 30 is connected to the main battery 20, and each of the capacitors C1 to C4 is connected in parallel to the auxiliary battery 40.

In this way, the capacitors C1 to C4 can be switched between series connection and parallel connection by the relay R. Below, when there is no need to distinguish between capacitors C1 to C4, they may be simply referred to as "capacitor C."

The control IC 50 is a control device that controls the entire power supply system 100. Note that the control IC corresponds to an example of a control section. Control IC 50 controls latch relay Rc, first relay R1, second relay R2, and each switch SW of capacitor unit 30 as main battery 20, capacitor unit 30, and auxiliary battery 40 are charged and discharged.

More specifically, the control IC 50 controls the voltage step-up operation or voltage step-down operation of the capacitor section 30 by switching the connection destination of the switch SW during charging and discharging between the main battery 20 and the auxiliary battery 40. Details of this point will be explained below with reference to the drawings from FIG. 2 onwards.

First, a case in which power is supplied from the auxiliary battery 40 to the main battery 20 will be described. 2 and 3 are diagrams showing an example of a boosting operation by the capacitor section 30. In addition, below, a part of power supply system 100 is extracted and shown.

As shown in FIG. 2, when power is supplied from the auxiliary battery 40 to the main battery 20, first, each capacitor C is connected in parallel to the auxiliary battery 40 by connecting the second relay R2. That is, in this case, the control IC 50 connects the second relay R2 with each switch SW connected to the first ground G1 side.

As a result, power is supplied from the auxiliary battery 40 to each capacitor C, as shown by the thick line in FIG. Note that the control IC 50 can calculate the charging capacity of each capacitor section 30 by measuring the current charged and discharged from the capacitor section 30 using an ammeter.

Thereafter, when the control IC 50 finishes supplying power to each capacitor C from the auxiliary battery 40, it connects each switch SW to the corresponding capacitor C2 to C3 or the second ground G2, as shown in FIG.

Thereby, as shown in FIG. 3, since the capacitors C are connected in series, each 12V capacitor C can be operated as one 48V storage battery.

In this state, control IC 50 can supply 48V power to main battery 20 from capacitors C1 to C4 by connecting latch relay Rc and first relay R1.

In this way, in the buck-boost device 1, when power is supplied from the auxiliary battery 40 to the main battery 20, after power is supplied from the auxiliary battery 40 to each capacitor C, the capacitors C1 to C4 are connected in series, and from the capacitor C Power is supplied to the main battery 20.

Next, the operation when power is supplied from the main battery 20 to the auxiliary battery 40 will be described using FIGS. 4 and 5. 4 and 5 are diagrams showing an example of a step-down operation by the capacitor section 30.

As shown in FIG. 4, when power is supplied from the main battery 20 to the auxiliary battery 40, the capacitors C1 to C4 are first connected in series by the switch SW, thereby causing the capacitors C1 to C4 to function as a 48V storage battery.

Then, by connecting the latch relay Rc and the first relay R1, power supply from the main battery 20 to each capacitor C is started. When power supply from the main battery 20 to each capacitor C is finished, as shown in FIG. 5, each capacitor C is rearranged to be connected in parallel by connecting each relay R to the first ground G1.

Thereafter, by connecting the second relay R2, 12V power is supplied to the auxiliary battery 40 from each of the capacitors C1 to C4.

Next, the voltage step-up operation and the voltage-down operation will be schematically explained using FIGS. 6 and 7. FIG. 6 is a schematic diagram of the boost operation. FIG. 7 is a schematic diagram of the voltage lowering operation. As shown in FIG. 6, during step-down operation, after power is supplied from the auxiliary battery 40 to each of the capacitors C1 to C4, the capacitors C1 to C4 are connected in series by a relay R to function as a 48V storage battery. , power is supplied to the main battery 20 from the capacitors C1 to C4.

In addition, as shown in FIG. 7, during step-down operation, each capacitor C1 to C4 is connected in series by a relay R, so that power is supplied from the main battery 20 to the capacitors C1 to C4 as a 48V storage battery. . Thereafter, by disconnecting the capacitors C1 to C4, each of the capacitors C1 to C4 is replaced with a 12V storage battery, and then power is supplied to the auxiliary battery 40 from each of the capacitors C1 to C4.

In this way, the buck-boost device 1 according to the embodiment can perform buck-boost by the capacitor section 30 by switching each switch SW to switch between parallel connection and series connection of each of the capacitors C1 to C4.

Further, in the buck-boost device 1 according to the embodiment, in the buck-boost operation by the capacitor unit 30, it is only necessary to switch each switch SW, so compared to the case where the buck-boost operation is performed using a DC/DC converter, for example, It becomes possible to simplify the control of the pressure operation.

In addition, in the buck-boost device 1, when charging and discharging between the auxiliary battery 40 and each capacitor C1 to C4, the charging capacity of each capacitor C1 to C4 is set so that a potential difference does not occur in each capacitor C1 to C4. It will be equalized. That is, the step-up/down device 1 can suppress unevenness in the battery life of each capacitor C1-C4 by averaging the storage capacity of each capacitor C1-C4.

Next, the processing procedure executed by the control IC 50 will be described using FIGS. 8 and 9. 8 and 9 are flowcharts showing the processing procedure executed by the control IC 50. First, with reference to FIG. 8, a procedure for boosting the voltage when power is supplied from the auxiliary battery 40 to the main battery 20 will be described.

As shown in FIG. 8, the control IC 50 determines whether the battery voltage of the main battery 20 is below the threshold value (step S101), and if the battery voltage of the main battery 20 is below the threshold value (step S101, Yes), the control IC 50 makes a correction. It is determined whether the battery voltage of the machine battery 40 is equal to or higher than a threshold value (step S102).

That is, in the determination in step S101, it is determined whether or not the main battery 20 needs to be charged, and in the determination in step S102, it is determined whether or not power is to be supplied from the auxiliary battery 40 to the main battery 20.

If the battery voltage of the auxiliary battery 40 is equal to or higher than the threshold value in the determination in step S102 (step S102, Yes), the control IC 50 connects the capacitors C1 to C4 in parallel (step S103). That is, in step S103, each capacitor C1 to C4 is disconnected by the switch SW.

After that, the control IC 50 supplies power to the capacitors C1 to C4 from the auxiliary battery 40 (step S104), and rearranges the capacitors C1 to C4 into series by using the switch SW (step S105).

Then, the control IC 50 supplies power to the main battery 20 from the series-connected capacitors C1 to C4 (step S106), and ends the process. Further, the control IC 50 determines whether the battery voltage of the main battery 20 exceeds the threshold value in the determination in step S101, or if the battery voltage of the auxiliary battery 40 is less than the threshold value in the determination in step S102 (steps S101/S102). , No), the step-up operation is not performed (step S107), and the process ends.

Next, the processing procedure of the control IC 50 during voltage reduction will be described using FIG. 9. As shown in FIG. 9, the control IC 50 determines whether the battery voltage of the auxiliary battery 40 is below the threshold (step S111), and if the battery voltage is below the threshold (step S111, Yes), the main battery 20 It is determined whether the battery voltage of is equal to or higher than a threshold value (step S112).

If the battery voltage of the main battery 20 is equal to or higher than the threshold value in the determination in step S112 (step S112, Yes), the control IC 50 connects the capacitors C1 to C4 in series using the switch SW (step S113).

Subsequently, the control IC 50 supplies power from the main battery 20 to the capacitors C1 to C4 connected in series (step S114), and rearranges the capacitors C1 to C4 in parallel using the switch SW (step S115).

After that, the control IC 50 supplies power to the auxiliary battery 40 from the capacitors C1 to C4 (step S116), and ends the process. Further, the control IC 50 determines whether the battery voltage of the auxiliary battery 40 exceeds the threshold value in the determination of step S111, or if the battery voltage of the main battery 20 is less than the threshold value in the determination of step S112 (steps S111/S112). , No), the voltage reduction operation is not performed (step S117), and the process ends.

As described above, the buck-boost device 1 according to the embodiment includes a plurality of capacitors C1 to C4 and a plurality of switches SW. The plurality of capacitors C1 to C4 are provided between the main battery 20 (an example of a first battery) and an auxiliary battery 40 (second battery) whose rated voltage is lower than that of the main battery, and one end is connected to the main battery 20. and are connected to the auxiliary battery 40 in parallel.

The plurality of switches SW are provided for each of the plurality of capacitors C1 to C4, and switch the connection state with the adjacent capacitors C2 to C4. Therefore, according to the voltage step-up/down device 1 according to the embodiment, the voltage step-up/down operation can be performed with easy control.

Incidentally, in the above-described embodiment, a case has been described in which step-up and step-down is performed with the capacitor unit 30 interposed when charging and discharging between the main battery 20 and the auxiliary battery 40, but the present invention is not limited to this. isn't it.

That is, for example, power supplied from an external power source such as the MG 11 may be directly supplied to the capacitor section 30, and then power may be supplied from the capacitor section 30 to the main battery 20 or the auxiliary battery 40. Alternatively, power may be directly supplied from the capacitor section 30 to the MG 11 or the load 12 without going through the main battery 20 or the auxiliary battery 40.

Particularly when voltage fluctuations are large, direct charging and discharging between main battery 20 or auxiliary battery 40 and MG 11 or load 12 will accelerate deterioration of main battery 20 or auxiliary battery 40.

On the other hand, by directly charging and discharging between the capacitor section 30 and the MG 11 or the load 12, it is possible to suppress deterioration of the main battery 20 or the auxiliary battery 40.

Examples of cases where voltage fluctuations are large include when the MG 11 starts the engine 10, when the MG 11 generates electricity as the vehicle decelerates, when the electric power steering operates, and when the ABS (Anti-lock Braking System) operates due to sudden braking. can be mentioned.

When charging and discharging between the capacitor section 30 and the MG11, the capacitors C1 to C4 are connected in series using the switch SW, and when charging and discharging between the capacitor section 30 and the load 12, the switch SW is disconnected. It is preferable to connect the capacitors C1 to C4 in parallel.

Further, in the above-described embodiment, a case has been described in which the voltage step-up/down device 1 is installed in the power supply system 100 installed in a vehicle, but the invention is not limited to this. That is, it is also possible to apply the present invention to other systems configured with a plurality of secondary batteries having different rated voltages.

Furthermore, in the embodiment described above, since the main battery 20 is 48V and the auxiliary battery 40 is 12V, a case has been described in which the capacitor section 30 is provided with four capacitors C1 to C4 each having a voltage of 12V. It is not limited.

That is, the number and rated voltage of each capacitor may be arbitrarily changed depending on the rated voltages of the first battery and the second battery. Further, the capacitor section 30 can be operated as a substitute for a DC/DC converter.

The capacitor section 30 does not necessarily need to be provided between the first battery and the second battery, and may be provided in place of the DCDC converter at a position where a conventional DCDC converter is provided.

Further advantages and modifications can be easily deduced by those skilled in the art. Therefore, the broader aspects of the invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various changes may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

1 step-up/down device 10 engine 12 load 20 main battery (an example of the first battery)
30 Capacitor section 40 Auxiliary battery (an example of the second battery)
50 Control IC (an example of a control unit)
C, C1 to C4 Capacitor G1 1st ground G2 2nd ground R1 1st relay R2 2nd relay Rc Latch relay SW Switch

Claims (5)

A plurality of capacitors are provided between a first battery and a second battery having a lower rated voltage than the first battery, one end of which is connected to the first battery, and each of which is connected to the second battery in parallel;
a plurality of switches provided on each of the plurality of capacitors and switching a connection state with the adjacent capacitor ;
The plurality of switches are
When connecting the plurality of capacitors to the first battery, the capacitor on the opposite side of the first battery is connected to a ground corresponding to the rated voltage of the first battery, with the adjacent capacitors being connected to each other. ,
When connecting the plurality of capacitors to the second battery, each of the plurality of capacitors is connected to a ground corresponding to the rated voltage of the second battery, with the adjacent capacitors being separated from each other.
A step-up/down device characterized by: The step-up/down device according to claim 1 , further comprising a control section that controls the switch during charging and discharging between the first battery and the second battery. The control unit includes:
When power is supplied from the first battery to the second battery, the switch connects the adjacent capacitors, and after power is supplied from the first battery to the capacitor, the switch disconnects the capacitors from each other. The step-up/down device according to claim 2 , wherein power is supplied from the capacitor to the second battery. The control unit includes:
When power is supplied from the second battery to the first battery, the capacitors are separated from each other by the switch, and after power is supplied from the second battery to the capacitor, the capacitors are connected to each other by the switch, The step-up/down device according to claim 2 or 3 , wherein power is supplied from the capacitor to the first battery. A plurality of capacitors are provided between a first battery and a second battery having a lower rated voltage than the first battery, one end of which is connected to the first battery, and each of which is connected in parallel to the second battery; ,
a plurality of switches provided on each of the plurality of capacitors and switching the connection state with the adjacent capacitor;
A control step of controlling the switch during charging and discharging between the first battery and the second battery ,
The plurality of switches are
When connecting the plurality of capacitors to the first battery, the capacitor on the opposite side of the first battery is connected to a ground corresponding to the rated voltage of the first battery, with adjacent capacitors being connected to each other. ,
When connecting the plurality of capacitors to the second battery, each of the plurality of capacitors is connected to a ground corresponding to the rated voltage of the second battery while the adjacent capacitors are separated from each other.
Step-up/down method.

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