JP2012143149A - Battery remaining capacity detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power supply to electronic components.SOLUTION: The battery remaining capacity detecting device comprises: voltage conversion means to step down voltage of high voltage accumulating means and supply it to low voltage accumulating means capable of supplying electric power to a plurality of electronic components; operation state detection means which detects the operation states of the plurality of electronic components; state detection means which detects the state of the low voltage accumulating means; and output voltage control means which controls output voltage of the voltage conversion means based on the operation states. The output voltage control means changes the output voltage of the voltage conversion means based on the state of the low voltage accumulating means detected by the state detection means.

Description

  The present invention relates to an apparatus for controlling the output voltage of power conversion means that steps down the voltage of a high-voltage storage means and supplies the low-voltage storage means that can supply power to a plurality of electronic components.

Conventionally, in a system including a DC / DC converter that steps down the power of a high-voltage battery and supplies it to a low-voltage battery that can supply power to auxiliary equipment, the DC / DC converter is based on the estimated power consumption of the auxiliary equipment. A technique for controlling the output voltage is known (see Patent Document 1).

JP 2004-320877 A

However, in the conventional technology, if the estimated power consumption of the auxiliary machinery is large, the output voltage of the DC / DC converter is increased. However, if the output voltage is increased, the power consumption of the auxiliary machinery, harness, etc. further increases. There is a problem of doing.

  The power control device according to the present invention steps down the voltage of the high voltage storage means and supplies it to the low voltage storage means capable of supplying power to a plurality of electronic components, and the operation state of the plurality of electronic components. And an output voltage control means for controlling the output voltage of the voltage conversion means, detects the state of the low voltage storage means, and changes the output voltage of the voltage conversion means based on the state of the low voltage storage means It is characterized by doing.

According to the power control apparatus of the present invention, the output voltage of the voltage conversion means can be set appropriately.

Diagram showing the relationship between the voltage applied to a component whose current consumption is proportional to the applied voltage, and the current consumption and power consumption The figure which shows the relation between the applied voltage to the part which has a constant voltage circuit inside, current consumption and power consumption The figure which shows the structure of the electric power system containing the electric power control apparatus in 1st Embodiment. The flowchart which shows the processing content performed by the electric power control apparatus in 1st Embodiment. The figure which shows the structure of the electric power system containing the electric power control apparatus in 2nd Embodiment. The flowchart which shows the processing content performed by the electric power control apparatus in 2nd Embodiment. The figure which shows the structure of the electric power system containing the electric power control apparatus in 3rd Embodiment. The flowchart which shows the processing content performed by the electric power control apparatus in 3rd Embodiment. The figure which shows the structure of the electric power system containing the electric power control apparatus in 4th Embodiment. The flowchart which shows the processing content performed by the power control apparatus in 4th Embodiment.

Hereinafter, an example in which the power control apparatus according to the present invention is applied to a hybrid vehicle will be described. In a hybrid vehicle, reducing the power consumption of electrical components mounted on the vehicle leads to an improvement in the fuel consumption of the vehicle and an improvement in the amount of electric power that can be distributed to the driving force of the vehicle. The relationship of the consumption current (power consumption) with respect to the applied voltage of the electrical component is roughly divided into the following two types.

The first is a component whose current consumption is proportional to the applied voltage. Examples of such parts include a light, a rear defogger, a harness, and the like. FIG. 1 is a diagram showing the relationship between the voltage applied to such a component, current consumption, and power consumption. As shown in FIG. 1, when the applied voltage increases, the current consumption increases in proportion to the applied voltage. Since power consumption is the product of applied voltage and current consumption, power consumption is proportional to the square of the applied voltage.

The second is a component that has a constant voltage circuit inside and does not increase the current consumption greatly even when the applied voltage becomes higher than a predetermined voltage. An example of such a component is an ECU. FIG. 2 is a diagram illustrating the relationship between the voltage applied to such a component, current consumption, and power consumption. When the applied voltage is increased, the current consumption does not increase greatly because the components do not operate in a range lower than the set voltage of the internal constant voltage circuit. When the applied voltage is further increased and becomes close to the set voltage, the constant voltage circuit operates and current consumption increases. When the applied voltage becomes higher than the set voltage, the voltage in the component becomes a constant voltage by the constant voltage circuit, and the current consumption becomes almost constant. Since power consumption is the product of applied voltage and current consumption, the relationship shown in FIG. 2 is obtained.

<< First Embodiment >>
FIG. 3 is a diagram showing an outline of a power system for a hybrid vehicle equipped with the power control apparatus according to the first embodiment. The DC / DC converter 20 steps down the voltage of the high voltage battery (high voltage storage means) 10 and supplies it to the auxiliary battery (low voltage storage means) 40 that can supply power to the plurality of electrical components Z0 to Zn. . A fusible link box 30 which is a kind of fuse is provided between the DC / DC converter 20, the auxiliary battery 40 and the power distribution unit 50.

The power distribution unit 50 has a relay (not shown) for distributing power to each of the electrical components Z0 to Zn for each electrical component Z0 to Zn, and each relay (not shown) based on an operation request from the user. By turning on / off, power supply to each of the electrical components Z0 to Zn is controlled. The power distribution unit 50 also transmits information about the ON / OFF state of each relay, that is, the operation state of each electrical component Z0 to Zn, to the ECU 70 described later.

The ECU 70 has data of a minimum voltage at which each of the electrical components Z0 to Zn can operate (hereinafter referred to as an operable minimum voltage) in a memory (not shown). The output voltage of the DC / DC converter 20 is determined based on the information on the operating state of each electrical component Z0 to Zn that is input.

FIG. 4 is a flowchart showing the contents of processing performed by the power control apparatus according to the first embodiment. ECU70 starts the process which starts from step S10, for example for every predetermined time after starting of a vehicle. In step S10, information on the operating state of each electrical component Z0 to Zn is input from the power distribution unit 50, and the process proceeds to step S20.

In step S20, the output voltage of the DC / DC converter 20 is determined. Specifically, based on the information on the operating state of each electrical component Z0 to Zn input from the power distribution unit 50, the operating electrical component is identified, and among the operable minimum voltages of the identified electrical component, The lowest operable voltage with the highest voltage value is set as the output voltage of the C / DC converter 20.

In step S30 following step S20, the output voltage determined in step S20 is transmitted to the DC / DC converter 20 as an output voltage command value. The DC / DC converter 20 outputs a voltage corresponding to the output voltage command value input from the ECU 70.

That is, since the output of the DC / DC converter 20 is set to the lowest operable voltage with the highest voltage value among the operable minimum voltages of the operating electrical components, the power consumption of the electrical components can be reduced. . For example, if the applied voltage of an electrical component whose current consumption is proportional to the applied voltage is 14.5 V and the current consumption is 50 A, if the applied voltage is reduced by 1 V to 13.5 V, the current consumption will be 47 A (50 × 13.5 /14.5=47), and power consumption can be reduced by 90 W (= 725-635).

According to the power control apparatus in the first embodiment, the voltage of the high voltage battery 10 is stepped down and supplied to the auxiliary battery 40 that can supply power to the plurality of electrical components Z0 to Zn. 20, and controls the output voltage of the DC / DC converter 20 based on the operable minimum voltage of the operating electrical component among the minimum voltage (operable minimum voltage) at which the electronic component can operate. Particularly, since the output voltage of the DC / DC converter 20 is controlled based on the lowest operable voltage of the highest voltage value among the operable minimum voltages of the operating electrical components, the voltage applied to the plurality of electrical components is controlled. Can be minimized, and the output voltage of the DC / DC converter 20 can be effectively reduced. Thereby, the electric energy which can be distributed to the fuel consumption of a vehicle and the driving force of a vehicle can be improved.

<< Second Embodiment >>
FIG. 5 is a diagram illustrating an outline of a power system of a hybrid vehicle equipped with the power control apparatus according to the second embodiment. The power control apparatus in the second embodiment includes a current sensor 80 in addition to the configuration of the power control apparatus in the first embodiment shown in FIG. The current sensor 80 detects the charging / discharging current of the auxiliary battery 40 and outputs it to the ECU 70.

In the power control apparatus in the second embodiment, the charging state of the auxiliary battery 40 is detected based on the charging / discharging current of the auxiliary battery 40 detected by the current sensor 80, and the detected charging state of the auxiliary battery 40 is also taken into consideration. Then, the output voltage of the DC / DC converter 20 is determined.

FIG. 6 is a flowchart showing the contents of processing performed by the power control apparatus according to the second embodiment. ECU70 starts the process which starts from step S10, for example for every predetermined time after starting of a vehicle. Of the processes in the flowchart shown in FIG. 6, steps that perform the same processes as those in the flowchart shown in FIG. 4 are given the same reference numerals, and detailed descriptions thereof are omitted.

In step S100 following step S10, the charging / discharging current value of the auxiliary battery detected by the current sensor 80 is input, and the process proceeds to step S110. In step S110, it is determined whether or not the charging state of the auxiliary battery 40 is good. Here, if the remaining capacity of the auxiliary battery 40 is equal to or greater than the predetermined capacity, it is determined that the charged state of the auxiliary battery 40 is good. If the remaining capacity is less than the predetermined capacity, the charged state of the auxiliary battery 40 is not good. Judge that there is no. The remaining capacity of the auxiliary battery 40 is obtained by using a known method of integrating the charge / discharge current of the auxiliary battery 40 detected by the current sensor 80. The predetermined capacity is set to an appropriate value by experiment or the like.

If it is determined in step S110 that the charging state of the auxiliary battery 40 is good, the process proceeds to step S20, and if it is determined that the charging state of the auxiliary battery 40 is not good, the process proceeds to step S120. In step S120, the output voltage of the DC / DC converter 20 is determined based on the state of charge of the auxiliary battery 40, the operating state of each electrical component Z0-Zn, and the minimum operable voltage of each electrical component. Here, based on the information on the operating state of each electrical component Z0 to Zn input from the power distribution unit 50, the operating electrical component is identified, and the highest voltage among the minimum operable voltages of the identified electrical component. The lowest operable voltage with a high value is corrected based on the remaining capacity of the auxiliary battery 40. The correction is performed so that the voltage value increases as the remaining capacity of the auxiliary battery 40 decreases. The voltage value corrected based on the remaining capacity of the auxiliary battery 40 is used as the output voltage of the DC converter 20.

When the process of step S20 or step S120 is performed, the process proceeds to step S30. The process of step S30 is the same as the process of step S30 of the flowchart shown in FIG.

According to the power control apparatus in the second embodiment, as in the power control apparatus in the first embodiment, the lowest operable voltage with the highest voltage value among the operable minimum voltages of the operating electrical components. Based on the voltage, the output voltage of the DC / DC converter 20 is controlled. In particular, since the output voltage of the DC / DC converter 20 is changed based on the charging state of the auxiliary battery 40, an appropriate output voltage can be set according to the charging state of the auxiliary battery 40.

In particular, according to the power control apparatus in the second embodiment, when the remaining capacity of the auxiliary battery 40 is lower than a predetermined capacity, the DC / DC converter 20 is compared to the case where the remaining capacity is equal to or larger than the predetermined capacity. Therefore, it is possible to suppress the voltage applied to the plurality of electrical components while suppressing the auxiliary battery 40 from being overdischarged. Further, according to the power control device in the second embodiment, the lower the remaining capacity of the auxiliary battery 40, the higher the output voltage of the DC / DC converter 20, so that the remaining capacity of the auxiliary battery 40 is maintained. An appropriate output voltage can be set according to the response.

<< Third Embodiment >>
FIG. 7 is a diagram illustrating an outline of a power system of a hybrid vehicle equipped with the power control apparatus according to the third embodiment. The power control apparatus in the third embodiment includes a temperature sensor 82 in addition to the configuration of the power control apparatus in the second embodiment shown in FIG. The temperature sensor 82 detects the temperature of the auxiliary battery 40 and outputs it to the ECU 70.

In the power control apparatus in the third embodiment, the output voltage of the DC / DC converter 20 is determined in consideration of the temperature of the auxiliary battery 40 detected by the temperature sensor 82.

FIG. 8 is a flowchart illustrating the processing contents performed by the power control apparatus according to the third embodiment. ECU70 starts the process which starts from step S10, for example for every predetermined time after starting of a vehicle. Of the processes in the flowchart shown in FIG. 8, steps that perform the same processes as those in the flowchart shown in FIG.

In step S200 following step S100, the temperature of the auxiliary battery 40 detected by the temperature sensor 82 is input, and the process proceeds to step S110. In step S110, it is determined whether or not the charging state of the auxiliary battery 40 is good. This determination is performed based on the remaining capacity of the auxiliary battery 40 as described above. If it is determined that the state of charge of the auxiliary battery 40 is good, the process proceeds to step S210, and if it is determined that the state of the auxiliary battery 40 is not good, the process proceeds to step S220.

In step S210, the output voltage of the DC / DC converter 20 is determined based on the temperature of the auxiliary battery 40, the operating state of each electrical component Z0-Zn, and the minimum operable voltage of each electrical component. Here, based on the information on the operating state of each electrical component Z0 to Zn input from the power distribution unit 50, the operating electrical component is identified, and the highest voltage among the minimum operable voltages of the identified electrical component. The voltage obtained by correcting the lowest operable voltage based on the temperature of the auxiliary battery 40 is used as the output voltage of the DC / DC converter 20. The voltage is corrected so that the output voltage of the DC / DC converter 20 becomes higher as the temperature of the auxiliary battery 40 becomes lower, and the output voltage of the DC / DC converter 20 becomes higher as the temperature of the auxiliary battery 40 becomes higher. Correct to lower. This is because the battery is difficult to be charged at low temperatures, so the applied voltage to the auxiliary battery 40 is increased, and at high temperatures, the applied voltage to the auxiliary battery 40 is decreased to avoid overcharging of the battery. It is.

On the other hand, in step S220, the DC / DC converter 20 is based on the charging state of the auxiliary battery 40, the temperature of the auxiliary battery 40, the operating state of each electrical component Z0 to Zn, and the operable minimum voltage of each electrical component. Determine the output voltage. Here, based on the information on the operating state of each electrical component Z0 to Zn input from the power distribution unit 50, the operating electrical component is identified, and the highest voltage among the minimum operable voltages of the identified electrical component. The minimum operable voltage with a high value is corrected based on the charging state and temperature of the auxiliary battery 40, and the corrected voltage is used as the output voltage of the DC / DC converter 20. The voltage is corrected so as to be higher as the remaining capacity of the auxiliary battery 40 is lower and as the temperature of the auxiliary battery 40 is lower, and to be lower as the temperature of the auxiliary battery 40 is higher. To do.

When the process of step S210 or step S220 is performed, the process proceeds to step S30. The processing in step S30 is the same as the processing in step S30 in the flowchart shown in FIG.

According to the power control device in the third embodiment, as in the power control device in the first embodiment, the lowest operable voltage with the highest voltage value among the lowest operable voltages of the operating electrical components. Based on the voltage, the output voltage of the DC / DC converter 20 is controlled. In particular, depending on the temperature of the auxiliary battery 40, the lower the temperature of the auxiliary battery 40, the higher the output voltage of the DC / DC converter 20, and the higher the temperature of the auxiliary battery 40, the higher the voltage of the DC / DC converter 20. Since the output voltage is lowered, an appropriate output voltage according to the state of the auxiliary battery 40 can be set.

<< 4th Embodiment >>
FIG. 9 is a diagram illustrating an outline of a power system of a hybrid vehicle equipped with the power control apparatus according to the fourth embodiment. The power control apparatus in the fourth embodiment includes an auxiliary battery relay 90 in addition to the configuration of the power control apparatus in the second embodiment shown in FIG. Auxiliary battery relay 90 is provided between fusible link box 30 and auxiliary battery 40 and is turned on / off based on a command from ECU 70.

The ECU 70 turns on the auxiliary battery relay 90 when the vehicle is started, and after starting the vehicle, the auxiliary battery relay is based on the state of the auxiliary battery 40 and the operating state of each electrical component Z0 to Zn. 90 on / off is controlled.

FIG. 10 is a flowchart illustrating the processing contents performed by the power control apparatus according to the fourth embodiment. ECU70 starts the process which starts from step S10, for example for every predetermined time after starting of a vehicle. Note that, in the processing of the flowchart shown in FIG. 10, steps that perform the same processing as the processing of the flowchart shown in FIG. 6 are assigned the same reference numerals and detailed description thereof is omitted.

In step S300 following step S100, it is determined whether or not the auxiliary battery relay 90 is turned off. Here, when the charging state of the auxiliary battery 40 is good and the consumption current of the operating electrical components can be supplied by the output current of the DC / DC converter 20, the auxiliary battery relay 90 is turned on. It is determined to be on, and otherwise it is determined to be off. It is determined whether or not the consumption current of the operating electrical component can be supplied by the output current of the DC / DC converter 20 based on the output possible voltage of the DC / DC converter 20 and the operation of the operating electrical component. Based on the lowest possible voltage. If the remaining capacity of auxiliary battery 40 is equal to or greater than a predetermined capacity, it is determined that the charged state of auxiliary battery 40 is good.

If it is determined in step S300 that the auxiliary battery relay 90 is turned off, the process proceeds to step S310. If it is determined that the auxiliary battery relay 90 is turned on, the process proceeds to step S320. In step S310, a command to turn off auxiliary battery relay 90 is issued. Based on this command, auxiliary battery relay 90 is turned off. When the auxiliary battery relay 90 is turned off, the process proceeds to step S20. The processing after step S20 is the same as the processing after step S20 in the flowchart shown in FIG.

On the other hand, in step S320, a command to turn on auxiliary battery relay 90 is issued. Based on this command, auxiliary battery relay 90 is turned on. When the auxiliary battery relay 90 is turned on, the process proceeds to step S120. The processing after step S120 is the same as the processing after step S120 in the flowchart shown in FIG.

According to the power control apparatus in the fourth embodiment, between the DC / DC converter 20 and the auxiliary battery 40 based on the state of the auxiliary battery 40 and the operating state of the plurality of electrical components Z0 to Zn. Since the connection / cut-off of the auxiliary battery relay 90 provided in is controlled, the output voltage of the DC / DC converter 20 can be further reduced when the auxiliary battery relay 90 is cut off. For example, when an electrical component having a high operable minimum voltage and a large current consumption, such as a headlight or a radiator fan, is not operating and the charging state of the auxiliary battery 40 is good, DC By shutting off between DC / DC converter 20 and auxiliary battery 40, the output voltage of DC / DC converter 20 can be further reduced.

The present invention is not limited to the first to fourth embodiments described above. For example, in each of the above-described embodiments, the example in which the power control device according to the present invention is applied to a hybrid vehicle has been described. However, the embodiment can be applied to an electric vehicle or a fuel cell vehicle, or applied to a system other than a vehicle. You can also

In each of the above-described embodiments, the processing in the flowchart has been described as being performed every predetermined time, but may be performed at an arbitrary timing. For example, the process may be performed only when the operation state of each of the electrical components Z0 to Zn is changed (from operation to stop or from stop to operation). In this case, if there is no change in the operating state, the processing of the flowchart is not performed, and therefore it is possible to prevent unnecessary processing from being performed.

When the auxiliary battery 40 is installed away from the DC / DC converter 20, the output voltage of the DC / DC converter 20 may not match the applied voltage of the auxiliary battery 40. In such a case, a voltage sensor for accurately detecting the applied voltage of the auxiliary battery 40 may be provided separately.

In the power control apparatus according to the fourth embodiment, the power control device is provided between the DC / DC converter 20 and the auxiliary battery 40 based on the state of the auxiliary battery 40 and the operating state of the plurality of electrical components Z0 to Zn. The connection / disconnection of the auxiliary battery relay 90 was controlled. Here, when the auxiliary battery relay 90 is cut off when the key switch of the vehicle (not shown) is turned off, the voltage drop of the auxiliary battery 40 can be suppressed even when the vehicle is left for a long time.

The correspondence between the constituent elements of the claims and the constituent elements of the first to fourth embodiments is as follows. That is, the DC / DC converter 20 is the voltage conversion means, the power distribution unit 50 is the operation state detection means, the ECU 70 is the storage means, the output voltage control means, and the connection / disconnection control means, and the current sensor 80 and the ECU 70 are in the state. The temperature sensor 82 constitutes the detection means, and the auxiliary battery relay 90 constitutes the connection / cutoff means. In addition, the above description is an example to the last, and when interpreting invention, it is not limited to the correspondence of the component of said embodiment and the component of this invention at all.

DESCRIPTION OF SYMBOLS 10 ... High voltage battery 20 ... DC / DC converter 30 ... Fusible link box 40 ... Auxiliary battery 50 ... Power distribution unit 70 ... ECU
80 ... Current sensor 82 ... Temperature sensor 90 ... Auxiliary battery relay Z0-Zn ... Electrical components

Claims (5)

A voltage conversion means for stepping down the voltage of the high voltage storage means and supplying the low voltage storage means capable of supplying power to a plurality of electronic components;
Operation state detection means for detecting operation states of the plurality of electronic components;
State detecting means for detecting the state of the low voltage storage means;
Output voltage control means for controlling the output voltage of the voltage conversion means based on the operating state,
The power control apparatus, wherein the output voltage control means changes the output voltage of the voltage conversion means based on the state of the low voltage storage means detected by the state detection means. The power control apparatus according to claim 1,
The state detection means detects a remaining capacity of the low voltage storage means,
When the remaining capacity of the low-voltage storage means detected by the state detection means is lower than a predetermined capacity, the output voltage control means is configured to perform the voltage conversion compared to when the remaining capacity is equal to or greater than the predetermined capacity. A power control apparatus characterized by increasing the output voltage of the means. The power control apparatus according to claim 1,
The output voltage control means increases the output voltage of the voltage conversion means as the remaining capacity of the low voltage storage means detected by the state detection means is lower. In the power control device according to any one of claims 1 to 3,
Temperature detecting means for detecting the temperature of the low voltage storage means,
The output voltage control unit changes the output voltage of the voltage conversion unit according to the temperature detected by the temperature detection unit. The power control apparatus according to claim 4,
The output voltage control means increases the output voltage of the voltage conversion means as the temperature detected by the temperature detection means decreases, and the output of the voltage conversion means increases as the temperature detected by the temperature detection means increases. A power control apparatus characterized by lowering a voltage.

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