JP2014011874A - Power supply control apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of power feed while preventing a malfunction in actuation of an electrical component such as a lamp in an electric vehicle.SOLUTION: A power supply control apparatus includes a driving battery 13, a 12 V battery 12 that is charged while having power fed from a power conversion circuit 14, and feeds power to an electrical component 18 when voltage fed from the power conversion circuit 14 gets lower than an open end voltage thereof, and a controller 15 that, when determining that a current value of an output current from the power conversion circuit 14 is equal to or lower than Iand a battery terminal voltage is equal to or higher than V, implements output voltage feedback control, which is intended to square a change quantity of the battery terminal voltage per a unit time with a gradient limiter that is a guide value of the change quantity, so that the battery terminal voltage becomes V, and that, in any other case, implements the output voltage feedback control so that the battery terminal voltage becomes V. By employing the power supply control apparatus, efficiency of power feed can be improved while a malfunction in actuation of the electrical component such as a lamp is prevented.

Description

  The present invention relates to a supply power control apparatus.

  In an electric vehicle, a driving battery mainly for driving a vehicle is mounted on the vehicle, and an auxiliary battery for supplying power to a low-voltage load such as an electrical component is provided. The auxiliary battery obtains energy by charging from the driving battery.

  The drive battery is set to have a high output voltage according to the voltage requirement of the drive system, and when charging the auxiliary battery, the DC / DC converter is used to adjust the voltage difference with the auxiliary battery and charge the battery simultaneously. Output to electrical equipment can also be performed.

  However, if the DC / DC converter always outputs, the output is performed even in a region where the output current, which is a low efficiency region, is small, and the efficiency of power supply deteriorates.

  Therefore, as a method for efficiently supplying power to the auxiliary battery without using a region where the DC / DC converter has low efficiency (region where the output current is small), Patent Document 1 discloses an output current of the DC / DC converter. Is determined to be less than or equal to a predetermined current value, the output of the DC / DC converter is stopped, and when it is determined that the terminal voltage of the auxiliary battery is less than the predetermined voltage value, the output of the DC / DC converter A control method of starting is proposed.

Japanese Patent No. 3796353

  However, if the output of the DC / DC converter is simply started or stopped as in the control method described above, sudden voltage fluctuations occur, causing malfunctions of the on-board electrical components such as lamp flickering. There is a possibility.

  Therefore, an object of the present invention is to improve the efficiency of power supply while preventing malfunction of electrical components such as lamps.

A supply power control apparatus according to a first invention for solving the above-mentioned problem is as follows.
A driving battery mounted on the vehicle;
An electrical component and an auxiliary battery connected to the drive battery via power conversion means for stepping down the power supplied from the drive battery; and
A power supply control device comprising a controller for controlling an output voltage from the power conversion means,
The controller changes the output voltage to a first target voltage value that is lower than the open-circuit voltage of the auxiliary battery, and stops power supply from the driving battery to the electrical component, Or, the output voltage is changed to a second target voltage value that is higher than the open-circuit voltage of the auxiliary battery, and output start control is performed to start power supply from the drive battery to the electrical component,
The amount of change of the output voltage per unit time is changed according to the operating state of the electrical component.

A supply power control apparatus according to a second invention for solving the above-mentioned problems is as follows.
In the supply power control apparatus according to the first invention,
The controller applies a gradient limiter that is a guide value of the change amount to the change amount per unit time of the output voltage,
The gradient limiter includes a first gradient limiter and a second gradient limiter having a change amount smaller than that of the first gradient limiter.
The controller selects the first gradient limiter or the second gradient limiter based on an operating state of the electrical component.

A supply power control apparatus according to a third invention for solving the above-mentioned problem is as follows.
In the supply power control apparatus according to the second invention,
The amount of change per unit time of the output voltage is changed according to the operating state of a predetermined electrical component among the electrical components,
The controller selects the first gradient limiter when all of the predetermined electrical components are inactive, and when one or more of the predetermined electrical components are active, The second gradient limiter is selected.

A supply power control apparatus according to a fourth invention for solving the above-mentioned problem is as follows.
In the supply power control apparatus according to the third invention,
The predetermined electrical component includes a headlamp.

  According to the supply power control apparatus according to the first aspect of the invention, it is necessary to change the amount of change per unit time of the battery terminal voltage according to the operating state of the electrical component so as not to affect the electrical component. Accordingly, rapid voltage fluctuation can be prevented.

  According to the power supply control apparatus according to the second aspect of the invention, the gradient limiter is applied to the amount of change per unit time of the battery terminal voltage, and the first gradient limiter and the first gradient limiter according to the operating state of the electrical component. By selecting the second gradient limiter having a smaller change amount than the gradient limiter, the change amount per unit time of the battery terminal voltage can be changed as necessary so as not to affect the electrical components. .

  According to the power supply control apparatus according to the third aspect of the invention, when all of the predetermined electrical components are in the non-operating state, the power conversion circuit of the power conversion circuit is promptly considered without affecting the operation of the predetermined electrical components. The output can be stopped or started, and when one or more of the predetermined electrical components are in operation, the output of the power conversion circuit is gradually stopped or started without affecting the operation of the predetermined electrical component. Can continue.

  According to the power supply control apparatus according to the fourth aspect of the present invention, when the headlamp is powered on, the output of the power conversion circuit can be gradually stopped or started while preventing flickering of the headlamp. When the headlamp power is OFF, the output of the power conversion circuit can be stopped or started early without considering flicker.

It is a block diagram of the supply power control apparatus which concerns on Example 1 of this invention. It is a flowchart explaining the action | operation of the power supply control apparatus which concerns on Example 1 of this invention. It is the graph which showed the relationship between the voltage output to an electrical component, and time at the time of using the supply power control apparatus which concerns on Example 1 of this invention, (a) showed the gradient limiter, (b) Indicates voltage fluctuation.

  Hereinafter, a power supply control device according to the present invention will be described with reference to the drawings in the embodiments.

  A supply power control apparatus according to Embodiment 1 of the present invention will be described in detail with reference to FIG. As shown in FIG. 1, the supply power control apparatus according to the first embodiment includes a DC / DC converter 11, a 12V battery 12, and a driving battery 13.

  An input end 11 a of the DC / DC converter 11 is connected to the drive battery 13, and an output end 11 b is connected to the 12V battery 12 and the electrical component 18. The DC / DC converter 11 includes a power conversion circuit (power conversion means) 14, a controller 15, a current sensor 16, a voltage sensor 17, and an electrical component 18 inside.

  The above-described drive battery 13 is a battery for mainly supplying power to the drive system.

  The 12V battery 12 described above is an auxiliary battery, is connected to the driving battery 13 via the power conversion circuit 14, is charged when power is supplied from the power conversion circuit 14, and is supplied from the power conversion circuit 14. When the voltage becomes lower than its own open-circuit voltage, power is supplied to the electrical component 18.

  The electrical component 18 described above is connected to the driving battery 13 via the power conversion circuit 14 and also connected to the 12V battery 12.

  The above-described power conversion circuit 14 performs step-down conversion on the power supplied from the driving battery 13 and supplies it to the electrical component 18 and the 12V battery 12.

  The above-described current sensor 16 measures the current value of the output current from the power conversion circuit 14.

  The voltage sensor 17 described above measures the voltage value of the terminal voltage of the 12V battery 12 (hereinafter referred to as the battery terminal voltage).

  The above-described controller 15 calculates a target voltage value based on the information input from the current sensor 16 and the voltage sensor 17, and adjusts the output voltage from the power conversion circuit 14 so that the battery terminal voltage follows the target voltage value. Control (hereinafter referred to as output voltage feedback control). At that time, two target voltage values are provided, and the target voltage values are switched according to the situation.

At this time, if the target voltage value is set as a voltage value V _LO (first target voltage value) lower than the open-circuit voltage of the 12V battery 12, power is supplied from the 12V battery 12 to the electrical component 18, and the power conversion circuit 14 Does not supply power.

On the other hand, when the target voltage value is set as a voltage value V _HI (second target voltage value) higher than the open-circuit voltage of the 12V battery 12, power is supplied from the power conversion circuit 14 to the 12V battery 12 and the electrical component 18. .

Therefore, V _LO is set in the controller 15 as the first and second target voltage values to stop the output from the power conversion circuit 14 and V _HI to start the output from the power conversion circuit 14, respectively. .

That is, if the maximum current value in the region where the output current from the power conversion circuit 14 is low efficiency is a predetermined current value I _A , the output current from the power conversion circuit 14 is equal to or less than I _A and the battery terminal voltage is V When it is equal to or higher than _LO , the controller 15 performs output stop control for changing the output voltage from the power conversion circuit 14 to the first target voltage value V _LO and stopping the power supply from the drive battery 13 to the electrical component 18. In other cases, output start control is performed in which the output voltage from the power conversion circuit 14 is changed to the second target voltage value V _HI and power supply from the drive battery 13 to the electrical component 18 is started. However, the current value when the output from the power conversion circuit 14 is started with the target voltage value set to V _HI is greater than I _A.

  Further, in order to prevent malfunctions of predetermined electrical components among the electrical components 18 due to voltage fluctuation, the amount of change per unit time of the battery terminal voltage output to the predetermined electrical components is prevented from abruptly. Since it is necessary, the amount of change must be changed according to the operating state of the electrical equipment. Therefore, in this embodiment, a gradient limiter that is a guide value for the amount of change is set. Here, the predetermined electrical component refers to a device whose main purpose is to be visually and audibly recognized by a passenger, and examples thereof include a lamp (headlight), radio, audio, car navigation, and the like. Can be mentioned. On the other hand, control devices such as ECUs that control in-vehicle devices correspond to those that are not included in the predetermined electrical components among the electrical components 18.

  When one or more of the predetermined electrical components are in operation, a second gradient limiter that is a change amount per unit time of the battery terminal voltage in a range that does not affect the operation of the predetermined electrical component is set. When the predetermined electrical component is not in operation, there is no need to consider malfunctions. Therefore, the first gradient limiter has a larger amount of change per unit time in the battery terminal voltage than the second gradient limiter. Apply. However, in the case of a vehicle provided with a fuel gauge, for example, even if the amount of change in the first gradient limiter is greater than a certain level, the fuel gauge may be affected. It may be the maximum amount of change per unit time of the battery terminal voltage within a range that does not affect the total.

  Next, the operation of the controller 15 will be described in detail with reference to the flowchart of FIG. Here, a case where a lamp is used as an example of the predetermined electrical component will be described.

In step S1, based on the information input from the current sensor 16 and the voltage sensor 17, it is determined whether or not the current value of the output current from the power conversion circuit 14 is equal to or lower than I _A and the battery terminal voltage is equal to or higher than V _LO. . If it is determined that the current value of the output current from the power conversion circuit 14 is equal to or lower than I _A and the battery terminal voltage is equal to or higher than V _LO , the process proceeds to step S2, otherwise the process proceeds to step S3.

In step S2, a first target voltage value _VLO is set.

In step S3, a second target voltage value V _HI is set.

  In step S4, it is determined whether or not the lamp is powered on. If it is ON, the process proceeds to step S5. If it is OFF, the process proceeds to step S6.

  In step S5, a second gradient limiter having an amount of change per unit time of the battery terminal voltage in a range that does not affect the operation of the predetermined electrical component is applied.

  In step S6, a first gradient limiter is applied.

  In step S7, output voltage feedback control is performed on the power conversion circuit 14 so as to follow the target voltage value after the gradient limiter is applied.

FIG. 3A is a graph for explaining the action of the gradient limiter. The vertical axis represents the voltage value, the horizontal axis represents the time, the alternate long and short dash line represents the target voltage value after the gradient limiter is applied, and V _B is the 12V battery 12. The voltage value of the open circuit voltage is shown. As can be seen from this, V _LO <V _B <V _HI . Hereinafter, the case where the power supply of the lamp is ON and the second gradient limiter is set will be described. The same is true for the first gradient limiter.

In FIG. 3B, a change in the battery terminal voltage when the gradient limiter shown in FIG. 3A is used is represented by a solid line. As can be seen from this graph, first, the target voltage value is V _HI at time 0 to a, and the battery terminal voltage matches this V _HI , but the output current from the power conversion circuit 14 at time a. When becomes less than I _A , the target voltage value is switched to V _LO from the above setting. Then, the battery terminal voltage decreases while following the target voltage value after the second gradient limiter is applied.

However, if the power conversion circuit 14 drops to V _B at time b, the power conversion circuit 14 stops supplying power and the 12V battery 12 supplies power from the above setting, and therefore cannot be controlled by the controller 15. Therefore, the battery terminal voltage does not follow the target voltage value after application of the second gradient limiter during times b to c.

Then, as the 12V battery 12 continues to supply power, the battery terminal voltage gradually decreases, and at time c, the battery terminal voltage becomes less than _VLO . Then, the target voltage value is switched to V _HI from the above setting. Then, at time cd, the battery terminal voltage rises following the target voltage value after the second gradient limiter is applied.

At time c, the battery terminal voltage exceeds V _LO immediately after it starts to rise, but as described above, the current value when the output from the power conversion circuit 14 is started with the target voltage value set to V _HI. because larger I _a, never target voltage value is switched from V _HI to V _LO also battery terminal voltage exceeds the V _LO. Therefore, the battery terminal voltage rises until time d and coincides with _VHI at time d.

That is, based on the information input from the current sensor 16 and the voltage sensor 17, the controller 15 has a current value of an output current from the power conversion circuit 14 that is equal to or less than a predetermined current value I _A and a battery terminal voltage that is an open end voltage of the 12V battery 12. If it is determined that the battery terminal voltage is equal to or higher than the lower target voltage value V _LO , the battery terminal voltage is set to the target voltage value V _LO. The output voltage feedback control is performed so that the target voltage value V _HI is higher than that, and the control applies a gradient limiter that is a guide value of the change amount to the change amount per unit time of the battery terminal voltage. It is something to be made. Thus, by applying the gradient limiter to the amount of change per unit time of the battery terminal voltage, a rapid voltage fluctuation can be prevented.

  The gradient limiter includes a first gradient limiter and a second gradient limiter having a change amount per unit time of the battery terminal voltage smaller than the first gradient limiter. The first gradient limiter or the second gradient limiter can be selected based on the operating state of the electrical component 18. Thus, by selecting the first gradient limiter and the second gradient limiter, the amount of change per unit time of the battery terminal voltage can be changed as necessary.

  Further, the second gradient limiter has a change amount per unit time of the battery terminal voltage in a range that does not affect the operation of the electrical component 18, and the controller 15 causes all the predetermined electrical components to be inactive. The first gradient limiter is selected, and if one or more of the predetermined electrical components are in operation, the second gradient limiter is selected. As a result, when one or more of the predetermined electrical components are operating, the output of the power conversion circuit 14 can be gradually stopped without affecting the operation of the predetermined electrical components. Other than the above, the output of the power conversion circuit 14 can be stopped early without considering the influence on the operation of a predetermined electrical component.

  The above-mentioned “change amount per unit time” is the change amount in one control cycle from the above-described steps S1 to S8.

  The predetermined electrical component mentioned above refers to a device whose main purpose is to recognize any of video, light, or sound, such as a lamp, radio, audio, and car navigation. Since these devices often feel inconvenient for passengers because of malfunctions caused by sudden voltage fluctuations, they are effective by applying this device.

  In particular, assuming a lamp, the second gradient limiter in the present apparatus has a change amount per unit time of the battery terminal voltage in a range where the lamp does not flicker. The first gradient limiter is selected when the lamp power is OFF. This makes it possible to gradually stop or start the output of the power conversion circuit while preventing flickering when the lamp power is on, and without considering flickering when the lamp power is off. The output of the power conversion circuit can be stopped or started early.

  By adopting the above-described configuration, this apparatus can improve the efficiency of power supply while preventing malfunctions of electrical components such as lamps.

  The present invention is suitable as a supply power control device used for an electric vehicle.

11 DC / DC converter 11a (DC / DC converter) input terminal 11b (DC / DC converter) output terminal 12 12V battery (auxiliary battery)
13 Driving Battery 14 Power Conversion Circuit 15 Controller 16 Current Sensor 17 Voltage Sensor 18 Electrical Equipment

Claims (4)

A driving battery mounted on the vehicle;
An electrical component and an auxiliary battery connected to the drive battery via power conversion means for stepping down the power supplied from the drive battery; and
A power supply control device comprising a controller for controlling an output voltage from the power conversion means,
The controller changes the output voltage to a first target voltage value that is lower than the open-circuit voltage of the auxiliary battery, and stops power supply from the driving battery to the electrical component, Or, the output voltage is changed to a second target voltage value that is higher than the open-circuit voltage of the auxiliary battery, and output start control is performed to start power supply from the drive battery to the electrical component,
The amount of change per unit time of the output voltage is changed according to the operating state of the electrical component. The controller applies a gradient limiter that is a guide value of the change amount to the change amount per unit time of the output voltage,
The gradient limiter includes a first gradient limiter and a second gradient limiter having a change amount smaller than that of the first gradient limiter.
The supply power control apparatus according to claim 1, wherein the controller selects the first gradient limiter or the second gradient limiter based on an operating state of the electrical component. The amount of change per unit time of the output voltage is changed according to the operating state of a predetermined electrical component among the electrical components,
The controller selects the first gradient limiter when all of the predetermined electrical components are inactive, and when one or more of the predetermined electrical components are active, The supply power control apparatus according to claim 2, wherein the second gradient limiter is selected.   The power supply control apparatus according to claim 3, wherein the predetermined electrical component includes a headlamp.

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