JP2014045631A - Control device for dc-dc converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for DC-DC converter, capable of suppressing an unstable phenomenon in a load while exhibiting high efficiency of a DC-DC converter.SOLUTION: There is provided a controller 31 that executes charging control for charging into an auxiliary battery 60 from a strong electric battery 20 through a DC-DC converter 30. For charging control in the controller 31, an allowable voltage fluctuation width as a voltage fluctuation width that does not generate a failure caused by a voltage fluctuation is previously set for each load in which electric power is supplied to the auxiliary battery 60. Fluctuation width change control is executed, which changes a voltage rise inclination (VD) during charging and a control low-voltage value VDL according to the magnitude of an allowable voltage fluctuation width of a load to be driven.

Description

  The present invention relates to a control device for a DC-DC converter.

  Conventionally, a technique for operating a DC-DC converter in an efficient region when charging a sub-battery via a DC-DC converter from a main battery is known (see, for example, Patent Document 1).

  This prior art performs constant current control for keeping the output current of the DC-DC converter at a predetermined current value in order to operate the DC-DC converter at a highly efficient operating point. Further, when the constant current control is being performed, if the state of charge of the second battery is detected and it is determined that the constant current control cannot be maintained, the control of the DC-DC converter is made constant at a constant voltage. The constant voltage control is maintained at a constant value.

JP 2007-135375 A

  However, since the above-described prior art is intended only for improving the efficiency of the DC-DC converter, the voltage fluctuation to the load becomes large, and there is a possibility that an unstable phenomenon such as flickering in the load may occur.

  The present invention has been made paying attention to the above problems, and provides a control device for a DC-DC converter capable of suppressing an unstable phenomenon in a load while exhibiting high efficiency of the DC-DC converter. For the purpose.

In order to achieve the above object, a control device for a DC-DC converter of the present invention comprises:
A control unit that performs charging control for charging the sub battery from the main battery via the DC-DC converter;
In the charging control, an allowable voltage fluctuation range that is a voltage fluctuation width that does not cause a problem due to voltage fluctuation is set in advance for each load supplied to the sub-battery in the charging control. A control apparatus for a DC-DC converter, wherein fluctuation range change control is performed to change a voltage rise slope and the control low voltage value in accordance with a size of the allowable voltage fluctuation range of the drive to be driven. It was.

In the control apparatus for a DC-DC converter according to the present invention, fluctuation range change control is performed to change the voltage rise gradient during charging and the control low voltage value according to the magnitude of the allowable voltage fluctuation range of the drive load. To do.
By changing the control low voltage value, the voltage fluctuation range of the power supplied to the load can be changed. Further, by changing the slope of voltage increase, it is possible to change the power distribution from the DC-DC converter to the load and the auxiliary battery.
Thus, by changing the setting of the voltage rise slope and the control low voltage value, it is possible to suppress the occurrence of voltage fluctuation exceeding the allowable voltage fluctuation range of the load, and to suppress the occurrence of problems due to voltage fluctuation. It becomes possible.

1 is an overall system configuration diagram showing an electric power supply system of an electric vehicle to which a control device for a DC-DC converter according to Embodiment 1 is applied. It is a characteristic view which shows the output current-efficiency characteristic of a DC-DC converter. 3 is a flowchart showing a flow of charging control processing of the DC-DC converter control apparatus according to Embodiment 1; It is explanatory drawing which shows the flow of an electric current with a DC-DC converter, a subbattery, and a load group. It is a time chart which shows the operation example of Embodiment 1 and a comparative example. 6 is a time chart showing an operation example when executing the fluctuation range change control of the first embodiment.

Hereinafter, the best mode for realizing a DC-DC converter control device of the present invention will be described based on Embodiment 1 shown in the drawings.
(Embodiment 1)
FIG. 1 is an overall system configuration diagram of an electric vehicle including a control device for a DC-DC converter according to Embodiment 1 of the present invention.

  As shown in the figure, the electric vehicle travels by driving the drive wheels WL and WR by the traveling electric motor 10. The electric vehicle includes a high-power battery 20 as a main battery, a DC-DC converter (hereinafter simply referred to as a converter) 30, and an inverter 40 on the power supply source side of the traveling electric motor 10.

  The electric motor 10 for traveling is controlled by the vehicle control device 50 for motor torque and motor rotation speed during traveling, and during braking, the regenerative braking torque is controlled based on the regenerative command from the vehicle control device 50. The vehicle control device 50 acquires various types of information from the sensor group 200 mounted on the vehicle and the load group 100 described later via the CAN communication 201.

An auxiliary battery 60 as a sub battery and a load group 100 are connected to the high voltage battery 20 via a converter 30.
That is, the high-power battery 20 is a main battery that supplies electric power to the traveling electric motor 10 that is a vehicle drive source, and the voltage when fully charged is several hundred volts (for example, about 300 to 400 volts). On the other hand, the auxiliary battery 60 is a sub-battery that supplies power to the load group 100, and the voltage at the time of full charge is a few dozen V (for example, about 14 to 15 V), and for example, a lead battery is used.

Converter 30 steps down the voltage of high-power battery 20 and supplies it to auxiliary battery 60 and load group 100.
The converter 30 includes a control unit 31 and a voltage sensor 32 inside.
Control unit 31 controls the operation of converter 30. Voltage sensor 32 detects the voltage of power supply system 120 connected to auxiliary battery 60 on the step-down side of converter 30 and load group 100.

  The load group 100 includes a meter device 101, a navigation system 102, an illumination device 103, an electric steering device 104, an electric brake device 105, a wiper device 106, an air conditioner (blower motor) 107, and the like. These are driven by electric power supplied from the auxiliary battery 60 or the converter 30.

  In the devices included in the load group 100, there is a small allowable voltage fluctuation width load that is a load in which an unstable phenomenon occurs when the voltage fluctuation increases. In the first embodiment, the lighting device 103, the wiper device 106, and the air conditioner 107 are exemplified as the small allowable voltage fluctuation width load. The lighting device 103 may cause flickering in lighting due to voltage fluctuation, and may give a passenger a sense of incongruity. Further, when the voltage fluctuations of the wiper device 106 and the air conditioner 107 increase, the motor drive speed changes, the wiper speed changes in the former, the air volume changes in the latter, and the passenger may feel uncomfortable.

  Furthermore, in the first embodiment, the allowable voltage fluctuation width among the above-described three small allowable voltage fluctuation width loads is from the smallest allowable voltage fluctuation characteristic in the order of lighting device 103 <wiper device 106 <air conditioner 107. It has become. That is, the characteristics are weak against voltage fluctuation in the above order.

Next, the converter 30 will be described.
FIG. 2 is a diagram showing the output current-efficiency characteristics of converter 30. As shown in FIG. 2, the efficiency of the converter 30 is highest when the output current ID is IDe. Hereinafter, the operating point when the output current of the converter 30 is IDe is referred to as a high efficiency operating point. The high-efficiency operating point IDe is, for example, a current of about several tens A, for example, about 50 A.

  In the first embodiment, the control unit 31 performs charge control for charging the auxiliary battery 60 from the high-power battery 20 via the converter 30 when the voltage of the auxiliary battery 60 decreases to a preset control low voltage value VDL. To do. Furthermore, in the first embodiment, the control unit 31 performs the low load request control and the high load request control based on the load request and the load request prediction in the load group 100 when executing the charge control. . In order to perform load request prediction, the control unit 31 acquires information based on the navigation system 102 via the vehicle control device 50.

(Explanation of control flow)
Next, charging control by the control unit 31 will be described based on the flowchart shown in FIG.
In step S1, the converter 30 is set to constant current control in which the output current ID is set to the high efficiency operating point IDe, and then the process proceeds to step S2.

  In step S <b> 2, it is determined whether or not drive prediction of a preset small allowable voltage fluctuation width load that is weak against voltage fluctuation is performed in the load group 100. If driving of the small allowable voltage fluctuation width load is not predicted, the process proceeds to step S3. If driving of the small allowable voltage fluctuation width load is predicted, the slope setting of the control voltage VD and the control low voltage value VDL after step S5 are predicted. Proceed to setting.

  The drive prediction of the small allowable voltage fluctuation width load is made based on various types of information obtained through the vehicle control device 50. The various types of information include map information from the navigation system 102, traffic information and weather information based on ITS (Intelligent Transport System) information obtained through this or other communication means, the navigation system 102, and others. The time information provided in the means is included. In addition, the outside air temperature and the passenger compartment temperature, which are information from the air conditioner 107 acquired via the vehicle control device 50, are included.

For example, when a tunnel exists in the course based on information from the navigation system 102 in advance, the automatic lighting driving of the lighting device 103 can be predicted in advance when approaching the tunnel, and prior to exiting the tunnel, Can be predicted to turn off. Similarly, automatic lighting and automatic extinguishing of the lighting device 103 can be predicted from the time information. In this case, it is possible to improve the time accuracy of sunrise and sunset based on latitude information based on map information.
Further, the driving of the wiper device 106 due to rain can be predicted in advance by weather information based on ITS information and the like.
Furthermore, based on the information on the outside air temperature and the passenger compartment temperature from the air conditioner 107, if the difference between the two differs by a preset temperature (for example, about 10 ° C.) or more, it is predicted that the air conditioner 107 will be driven. be able to.

  In step S3 that proceeds when the driving of the small allowable voltage fluctuation width load is not predicted, it is determined whether or not the small allowable voltage fluctuation width load is currently being driven. The process proceeds to S5, and the process proceeds to step S4 while the small allowable voltage fluctuation width load is not driven.

  In step S4 that proceeds when the drive prediction of the small allowable voltage fluctuation width load and the actual drive are not performed, the output current ID, the control high voltage value VDH, and the control low voltage value VDL of the converter 30 are set as follows.

Here, first, the output current ID, the control high voltage value VDH, and the control low voltage value VDL will be described.
The output current ID indicates an output during constant current control of the converter 30. In the time chart of FIG. 5, constant current control is executed between the time point t00 and the time point t01, and the output current ID at this time is driven at the high efficiency operating point IDe. In this case, the converter 30 is operated with high efficiency, whereby the auxiliary battery 60 is charged, and the voltage rise slope at this time is defined as the first voltage rise slope. Note that this first voltage rise slope is the steepest slope of the voltage rise slope in the first embodiment.

  The control high voltage value VDH is a voltage value for performing determination to switch from constant current control to constant voltage control in the control of the converter 30. That is, when the battery voltage VB reaches the control high voltage value VDH, charging is terminated and the converter 30 is switched to constant voltage control. Thereby, the auxiliary battery 60 is switched from the charged state to the discharged state. In FIG. 5 described above, the time point t01 indicates the time point when the battery voltage VB reaches the control high voltage value VDH and is switched to the constant voltage control.

  The control low voltage value VDL is a voltage value for determining that the discharge is terminated and the constant voltage control is terminated in the control of the converter 30. That is, when the battery voltage VB decreases to the control low voltage value VDL due to discharging, the constant voltage control of the converter 30 is terminated and switched to charging by constant current control or the like. In FIG. 5 described above, at time t02, the battery voltage VB reaches the control low voltage value VDL and the discharge is finished.

Next, each numerical value set in step S4 will be described.
In step S4, the output current (voltage gradient) ID is set to the high efficiency operating point IDe, the control high voltage value VDH is set to the preset upper limit voltage VDHmax, and the control low voltage value VDL is preset. The lower limit voltage VDLmin as the first control low voltage value is set.

  In step S4, the upper limit voltage VDHmax set to the control high voltage value VDH is an upper limit value set so as not to exceed the auxiliary battery 60 and the load group 100 in the power supply system 120 in order to protect the auxiliary battery 60 and the load group 100. is there. The upper limit voltage VDHmax is, for example, a voltage of less than 15V, and more specifically, is set to a value of the order of 14V.

  The lower limit voltage VDLmin corresponding to the first control low voltage value set to the control low voltage value VDL in step S4 is less than this value in order to protect the power supply system 120 to the auxiliary battery 60 and the load group 100. It is a lower limit value set so as not to occur. This lower limit voltage VDLmin is set to a voltage higher than 12V, for example, more specifically, a value around 13V.

Next, when the driving of the small allowable voltage fluctuation range load is predicted in step S2, or when the small allowable voltage fluctuation range load is actually driven in step S3, the processing after step S5, that is, the fluctuation range is performed. The change control will be described.
First, in step S5, it is determined whether or not the wiper device 106 is included in the small allowable voltage fluctuation width load that has been predicted or detected. If the wiper device 106 is included, the process proceeds to step S6, and the wiper device 106 is included. If not, the process proceeds to step S7.

At the time of driving or predicting driving of the wiper device 106, in step S6, candidate 1 is selected as the setting of the control voltage VD, the control high voltage value VDH, and the control low voltage value VDL.
As shown in FIG. 4, the control voltage VD is a voltage output from the converter 30 to the power supply system 120. In the candidate 1, the control voltage VD is set to VD0 + K2 (second voltage increase slope).
Here, VD0 is the current control voltage. K2 (second voltage rise slope) is a voltage rise per unit time, that is, a voltage rise slope, and is the second smallest (gradual) value as the slope used in the first embodiment. It is. More specifically, K2 is a slope enough to increase the voltage of 1V in several seconds (5 to 7 seconds).
The control high voltage value VDH is set to a preset upper limit voltage VDHmax.
The control low voltage value VDL is set to a preset first fluctuation suppressing voltage VDLyok1. The first fluctuation suppressing voltage VDLyok1 is a value set higher than the lower limit voltage VDLmin, and the first fluctuation suppressing voltage VDLyok1 and the second and third fluctuation suppressing voltages VDLyok2 and 3 described later. The second largest value.

  In step S5, which is performed when it is determined in step S5 that the wiper device 106 is not included in the small allowable voltage fluctuation width load, the illumination device 103 is included in the drive prediction in step S2 or the actual drive detection in step S3. It is determined whether or not. And when the illuminating device 103 is included, it progresses to step S8, and when the illuminating device 103 is not included, it progresses to step S9.

In step S8 that proceeds when actual driving or driving prediction of the lighting device 103 is included, the following candidate 2 is selected as the setting of the control voltage VD, the control high voltage value VDH, and the control low voltage value VDL.
In candidate 2, the control voltage VD is set to VD0 + K3 (third voltage increase slope). k3 (third voltage rise slope) is set to the smallest (gradual) slope in the voltage slope used in the first embodiment. Specifically, K3 (third voltage increase gradient) is a gradient that increases 1V in about 10 seconds (8 to 12 seconds).
The control high voltage value VDH is set to a preset upper limit voltage VDHmax.
The control low voltage value VDL is set to a preset second fluctuation suppressing voltage VDLyok2. The second fluctuation suppressing voltage VDLyok2 is a value set higher than the lower limit voltage VDLmin, and is the largest value among the first to second fluctuation suppressing voltages VDLyok1 to VDLyok1.

  In step S9, which proceeds when it is determined in step S7 that the illumination device 103 is not included in the small allowable voltage fluctuation width load, the air conditioner (blower motor) is used for the drive prediction in step S2 or the actual drive detection in step S3. It is determined whether or not 107 is included. If the air conditioner 107 is included, the process proceeds to step S10. If the air conditioner 107 is not included, the process proceeds to step S11.

In the case of operation detection or operation prediction of the air conditioner 107, in step S10, candidate 3 is selected as the setting of the control voltage VD, control voltage VD, control high voltage value VDH, and control low voltage value VDL.
In Candidate 3, the control voltage VD is set to VD0 + K4 (fourth voltage increase slope). In addition, K4 (fourth voltage increase slope) is set to the second smallest (gradual) voltage increase slope used in the first embodiment, that is, a gentle slope next to the first voltage increase slope. Has been. Specifically, the slope is such that 1 V is increased in a few seconds (4 to 6 seconds).
The control high voltage value VDH is set to a preset upper limit voltage VDHmax.
The control low voltage value VDL is set to a preset third fluctuation suppressing voltage VDLyok3. The third fluctuation suppressing voltage VDLyok3 is a value set higher than the lower limit voltage VDLmin, and is the lowest value among the first to third fluctuation suppressing voltages VDLyok1 to VDLyok1. That is, the size of VDLyok3 <VDLyok1 <VDLyok2 is set. In addition, the voltage increase gradient is set to K3 <K2 <K4 (the larger the value, the steeper the gradient).

  In step S11 that proceeds after any one or more of candidates 1 to 3 are set in steps S6, S8, and S10, based on the corresponding candidates 1 to 3, the control voltage VD, the control high voltage value VDH, and the control Set the low voltage value VDL. That is, as the control voltage VD, the one having the smallest (gradual) slope is selected from the corresponding second to fourth voltage rise slopes K2 to K4. The control low voltage value VDL is selected from the corresponding first to third fluctuation suppressing voltages VDLyok1 to yok3 having the largest value. In each of the candidates 1 to 3, the control high voltage value VDH is common to the upper limit voltage VDHmax.

  Next, in step S12 which proceeds after the setting in step S4 or the setting in step S11, it is determined whether or not the battery voltage VB is equal to the control high voltage value VDH. When the battery voltage VB is equal to the control high voltage value VDH, the process proceeds to step S13, and when both are not equal, the process proceeds to step S2.

In step S13 that proceeds when VB = VDH in step S12, the control voltage VD is controlled to the control low voltage value VDL, and the process proceeds to step S14.
In step S14, it is determined whether or not the battery voltage VB is equal to the control low voltage value VDL. If both are equal (VB = VDL), the process proceeds to repeat from step S1, and otherwise, The process returns to step S13.

(Operation of Embodiment 1)
Next, the operation of the first embodiment will be described based on a time chart.
<Comparative example>
In describing the operation of the first embodiment, first, an operation example of a comparative example performing the same operation as that of the prior art will be described based on the time chart of FIG. The operation of the time chart of FIG. 5 is equal to the normal operation in which the drive prediction of the small allowable voltage fluctuation width load and the actual drive are not performed in the first embodiment.

  In this case, the output current ID of the converter 30 is controlled to the high efficiency operating point IDe (step S4).

At this time, since converter 30 is operating at high efficiency operating point IDe, output current ID of converter 30 is supplied to auxiliary battery 60 and load group 100 as indicated by black arrows IB and IL in FIG. The Therefore, the auxiliary battery 60 is charged, and the load group 100 is consumed by the operating load.
At this time, the voltage increase slope when the battery voltage VB of the auxiliary battery 60 rises is the steepest first voltage increase slope, which is the slope between time points t0 to t01 in FIG.

Thereafter, from time t01 when battery voltage VB reaches control high voltage value VDH, converter 30 is switched to constant voltage control of control voltage VD = VDL (based on the processing of steps S12 → S13 → S14 → S13).
Therefore, the auxiliary battery 60 is discharged as indicated by the white arrow IB in FIG. 4 due to the power consumption of the load group 100, and as shown in FIG. 5, the battery voltage VB decreases from the time t01.

  Then, at time t02 when the battery voltage VB decreases to the control low voltage value VDL, the converter 30 is switched again to the constant current control in which the output current ID is operated at the high efficiency operating point IDe, and the above operation is repeated.

In the middle of performing such an operation, in the comparative example, when the small allowable voltage fluctuation width load is driven, the following problem may occur.
As described above, the battery voltage VB varies up and down between the control low voltage value VDL and the control high voltage value VDH. In particular, in a region t0R where the battery voltage VB is close to the control low voltage value VDL, etc., a load with large power consumption (for example, when the electric steering device 104 or the electric brake device 105 is frequently driven) The power supply due to the discharge of the battery 60 may not catch up with the consumption, and in this case, the battery voltage VB may be further lowered than the control low voltage value VDL.

  As described above, when the voltage fluctuation range of the battery voltage VB is large, flickering occurs in the lighting device 103 as the small allowable voltage fluctuation range load described above, the wiper wiping speed changes in the wiper device 106, or the air conditioner 107. There is a risk that the amount of air flow will change. In this case, the occupant may feel uncomfortable.

The first embodiment is aimed at preventing the occurrence of such a problem, and the operation at the time of driving prediction or driving at the time of the above-described small allowable voltage fluctuation width load will be described below.
<Operation of Embodiment 1>
FIG. 6 is a time chart showing the operation when the drive prediction of the small allowable voltage fluctuation width load is made in the first embodiment.

Here, at time t0, the drive prediction of the small allowable voltage fluctuation range load and the actual drive are not performed, and the same operation as the comparative example is performed. That is, similarly to the time point t00 in FIG. 5, the battery voltage VB increases with the first voltage increase slope based on the constant current control with the output current ID = IDe.
After that, at time t1, for example, driving prediction of a small allowable voltage fluctuation width load is made such that the tunnel of the course approaches and automatic lighting driving of the lighting apparatus 103 is predicted, and fluctuation width change control is executed.

  In this case, the control voltage VD, the control high voltage value VDH, and the control low voltage value VDL are set according to the small allowable voltage fluctuation width load predicted to be driven based on the processing in steps S5 to S11 in FIG. The

That is, in a plurality of small allowable voltage fluctuation width loads, the smaller the allowable voltage fluctuation width of the load predicted to be driven, the smaller the voltage rise slope is set (gradually) than the first voltage rise slope. The control low voltage value VDL is set higher than the lower limit voltage VDLmin as the voltage value. That is, the control low voltage value VDL is set higher than the lower limit voltage VDLmin by the amount indicated by the arrow β in the figure.
For example, when the driving prediction of the lighting device 103 is made as described above, VD = VD0 + K2 (second voltage rising slope, which is the slowest voltage rising slope), and VDL = VDLyok2 (largest control). Low voltage value).

Therefore, when the auxiliary battery 60 is charged between the time point t1 and the time point T2 in FIG. 6, the voltage increase slope is set more gently than the first voltage increase slope of ID = IDe, and the control low voltage is started from the time point t1. Set the value VDL to a large value.
As described above, when the voltage increase slope becomes gentle, when a load request is generated in the load group 100, a power supply margin from the converter 30 to the load group 100 can be secured. Thereby, the rapid fluctuation of the voltage in the load group 100 can be suppressed.

  Furthermore, since the control low voltage value VDL is set to be larger than the lower limit voltage VDLmin as the first control low voltage value after the time point t1, the control high voltage value is higher than the normal time (when the non-small allowable voltage fluctuation range load operation is performed). The voltage fluctuation range between the voltage value VDH and the control low voltage value VDL can be suppressed small.

  As described above, the voltage fluctuation width is suppressed within the allowable voltage fluctuation width in the small allowable voltage fluctuation width load, the flickering of the lighting device 103, the change in the wiper wiping speed of the wiper device 106, and the change in the blown air amount of the air conditioner 107 Can be suppressed. Therefore, it is possible to suppress the passenger from feeling uncomfortable due to these phenomena.

(Effect of Embodiment 1)
As described above, the control device for the DC-DC converter according to the first embodiment has the effects listed below.
a) The control device of the DC-DC converter of Embodiment 1
A DC-DC converter 30 capable of adjusting the voltage of the high-power battery 20 as a main battery and supplying power to a load group 100 including an auxiliary battery 60 and a plurality of loads as sub-batteries;
A voltage sensor 32 as battery voltage detection means for detecting the voltage of the auxiliary battery 60;
When the operation of the DC-DC converter 30 is controlled and the battery voltage VB of the auxiliary battery 60 decreases to a preset control low voltage value VDL, the high voltage battery 20 passes through the DC-DC converter 30 to the auxiliary battery 60. A control unit 31 that executes charge control for charging;
A control device for a DC-DC converter comprising:
In the charge control, the control unit 31 is set in advance with an allowable voltage fluctuation range, which is a voltage fluctuation width that does not cause a problem due to voltage fluctuation, for each load of the load group 100. Fluctuation width change control (processing of steps S5 to S11) is executed to change the low voltage value VDL according to the allowable voltage fluctuation width of the drive load.
Therefore, it is possible to suppress the voltage fluctuation exceeding the allowable voltage fluctuation width of the load from occurring in the battery voltage VB, and it is possible to suppress the occurrence of a malfunction due to the voltage fluctuation.

b) The control device of the DC-DC converter of Embodiment 1 is
When executing the fluctuation range change control, the control unit 31 sets the voltage increase inclination to be smaller as the allowable voltage fluctuation range of the drive load is smaller (steps S5 → S6, S7 → S8, S9 → S10). Features.
That is, by suppressing the voltage increase slope, it is possible to suppress the voltage fluctuation range per unit time. In addition, it is possible to secure a margin for supplying the power supplied from the converter 30 to the load group 100, thereby suppressing a sudden drop in the battery voltage VB due to the power consumption of the load group 100. The voltage fluctuation range per unit time can be suppressed.
Therefore, the smaller the allowable voltage fluctuation range of the drive load is, the smaller the voltage rise slope can be reduced, so that the voltage fluctuation range can be suppressed, and the occurrence of problems due to voltage fluctuation exceeding the allowable voltage fluctuation range of the load can be suppressed. .

c) The control device of the DC-DC converter of Embodiment 1 is
The control unit 31 is characterized in that the control low voltage value VDL is set to be larger as the allowable voltage fluctuation width of the driving load is smaller when the fluctuation width change control is executed (processing in steps S6, S8, S10, and S11). To do.
At the time of charging control, charging starts when the battery voltage VB decreases to the control low voltage value VDL. When the control low voltage value VDL is relatively increased, the minimum voltage value of the battery voltage VB is increased accordingly, and the fluctuation range of the battery voltage VB is suppressed.
As described above, the smaller the allowable voltage fluctuation range of the drive load is, the smaller the fluctuation range of the battery voltage VB is. Therefore, it is possible to suppress the occurrence of problems due to the voltage fluctuation exceeding the allowable voltage fluctuation range of the load.

d) The control device of the DC-DC converter of Embodiment 1 is
The control unit 31 is set in advance with a first voltage rise slope (IDD = IDe) and a first control low voltage value (VDLmin) as a voltage rise slope and a control low voltage value VDL used during charge control. A small allowable voltage fluctuation width load (103, 106, 107) having a relatively small allowable voltage fluctuation width is set in the load group 100,
When the small allowable voltage fluctuation width load (103, 106, 107) is driven, the control unit 31 converts the voltage rise slope and the control low voltage value VDL into the first voltage rise slope (IDD = IDe) by the fluctuation width change control. ) And the first control low voltage value (VDLmin) (steps S6, S8, S10 and S11).

e) The control device of the DC-DC converter of Embodiment 1 is
The load to be driven in the fluctuation range change control is characterized in that it is a load that is actually being driven among a plurality of loads in the load group 100 (steps S3 → S4 → S5 and subsequent processes).
In the present invention, since the voltage fluctuation range can be changed according to the allowable voltage fluctuation range of the load that is actually driven, it is possible to suppress the occurrence of problems due to voltage fluctuations in the load that is actually driven.

f) The control device for the DC-DC converter of Embodiment 1
The load to be driven in the fluctuation range change control is a load predicted to be driven in advance by the drive predicting means (the process of step S2) among a plurality of loads of the load group 100.
In this way, since the voltage rise slope and the control low voltage value VDL are changed before the time when the load starts driving, the load is actually started after the load is actually started, compared with the case where both are changed. Thus, it is possible to suppress the voltage fluctuation range during driving of the load.
Therefore, it is possible to more reliably suppress the occurrence of problems due to voltage fluctuations in the load. Furthermore, in the first embodiment, since the fluctuation range change control is executed for both the drive predicted and the actually driven, the time when the drive is actually started even if there is a prediction failure. Thus, it is possible to implement the fluctuation range change control.

g) The control device for the DC-DC converter of Embodiment 1
The drive predicting means (step S2) predicts driving of the load group 100 based on information from the vehicle control device 50 as information acquisition means for acquiring information including at least one of map information, weather information, and time information. It is characterized by doing.
The drive prediction means can perform drive prediction by performing drive prediction based on at least one of map information, weather information, and time information. Specifically, as shown in the first embodiment, driving prediction of the lighting device 103 can be performed by travel prediction based on map information from the navigation system 102. Similarly, it is possible to predict the driving of the wiper device 106 based on the weather information. Further, it is possible to predict driving of the lighting device 103 based on the time information.

h) The control device for the DC-DC converter of Embodiment 1
The controller 31 automatically turns on the lighting device 103 as a small allowable voltage fluctuation width load based on at least one of the map information and the time information obtained by the drive prediction means (step S2) via the vehicle control device 50. When predicting the fluctuation range, the fluctuation range change control is executed.
That is, as described in g) above, when the lighting device 103 is automatically turned on, if there is a tunnel in the future course based on the map information, it is possible to predict the automatic lighting of the lighting device 103 in advance. Further, based on the time information or in addition thereto, it is possible to predict the automatic lighting and extinguishing of the lighting device 103 according to the sunrise and sunset times based on the map information.
Therefore, on the basis of such automatic lighting prediction, fluctuation range change control according to the allowable voltage fluctuation range of the lighting device 103 as a small allowable voltage fluctuation width load is executed in advance to prevent occurrence of a malfunction due to voltage fluctuation. Can be suppressed.

j) The control device of the DC-DC converter of the first embodiment is
The control unit 31 performs fluctuation range change control when the drive prediction unit predicts driving of the wiper device 106 as a small allowable voltage fluctuation range load based on weather information acquired from the vehicle control device 50. And
That is, when rain is predicted based on the weather information, the operation of the wiper device 106 is predicted in advance. Therefore, the fluctuation range change control according to the allowable voltage fluctuation range of the wiper device 106 as the small allowable voltage fluctuation width load can be executed before the rain to suppress the occurrence of problems due to voltage fluctuations.

k) The control device of the DC-DC converter of Embodiment 1 is
The information from the vehicle control device 50 as the information acquisition means includes the outside air temperature and the passenger compartment temperature,
The controller 31 drives the fan of the air conditioner 107 as a small allowable voltage fluctuation width load when the drive predicting means (step S2) has a difference between the outside air temperature and the passenger compartment temperature larger than a preset value. When predicting, the fluctuation range change control is executed.
That is, based on the difference between the outside air temperature and the passenger compartment temperature, when the difference between the two is larger than the set value, the operation of the air conditioner 107 is predicted in advance. Therefore, before the driving of the air conditioner 107 is actually started, the fluctuation range change control according to the allowable voltage fluctuation range of the air conditioner 107 as the small allowable voltage fluctuation range load is executed, and a problem due to the voltage fluctuation occurs. Can be suppressed.

  As mentioned above, although the control apparatus of the DC-DC converter of this invention has been demonstrated based on embodiment, it is not restricted to this embodiment about a concrete structure, Each claim of a claim Design changes and additions are allowed without departing from the gist of the invention.

  For example, in the embodiment, an example in which the present invention is applied to an electric vehicle has been shown. However, as long as the vehicle is equipped with a main battery, a sub battery, and a DC-DC converter, the present invention can also be applied to other vehicles such as so-called hybrid vehicles. it can.

Further, in the embodiment, as a load, a meter device, a navigation system, a lighting device, an electric steering device, an electric brake device, a wiper device, an air conditioner (blower motor) are shown, but if it is driven by an auxiliary battery, It is not limited to these. Furthermore, the small allowable voltage fluctuation width load can be set as appropriate according to the actual allowable voltage fluctuation width, and is not limited to the lighting device, the wiper device, and the air conditioner described in the embodiment. For example, a meter display device or a navigation system display device in which the amount of light may change due to voltage fluctuations may be applied.
Similarly, the setting of the voltage increase slope and the setting of the control low voltage value may be appropriately set according to the characteristics of the small allowable voltage fluctuation width load, and are not limited to the characteristics shown in the first embodiment. .

ID Output current IDe High-efficiency operating point (first voltage rise slope)
K2 Second voltage rise slope K3 Third voltage rise slope K4 Fourth voltage rise slope VB Battery voltage VDL Control low voltage value VDLmin Lower limit voltage (first control low voltage value)
VDLyok1 First fluctuation suppressing voltage VDLyok2 Second fluctuation suppressing voltage VDLyok3 Third fluctuation suppressing voltage 20 High-power battery (main battery)
30 Converter 31 Control unit 32 Voltage sensor (battery voltage detection means)
40 Inverter (sub battery)
50 Vehicle Control Device 60 Auxiliary Battery 100 Load Group 101 Meter Device (Load)
102 Navigation system (load)
103 Illumination device (load: small allowable voltage fluctuation width load)
104 Electric steering device (load)
105 Electric brake device (load)
106 Wiper device (load: small allowable voltage fluctuation range load)
107 Air conditioner (load: small allowable voltage fluctuation range load)

Claims (10)

A DC-DC converter that adjusts the voltage of the main battery to supply power to the sub-battery and a plurality of loads;
Battery voltage detection means for detecting the voltage of the sub-battery;
Charging that controls the operation of the DC-DC converter and charges the sub-battery from the main battery via the DC-DC converter when the voltage of the sub-battery drops to a preset control low voltage value A control unit for executing control;
A control device for a DC-DC converter comprising:
In the charging control, the control unit is set in advance with an allowable voltage fluctuation range that is a voltage fluctuation width that does not cause a problem due to voltage fluctuation for each load. A control apparatus for a DC-DC converter, wherein fluctuation range change control for changing a low voltage value in accordance with a size of the allowable voltage fluctuation range of the load to be driven is executed. In the control apparatus of the DC-DC converter according to claim 1,
The control unit of the DC-DC converter according to claim 1, wherein the control unit sets the voltage increase slope to be smaller as the allowable voltage fluctuation range of the drive to be driven is smaller when the fluctuation range change control is executed. In the control apparatus of the DC-DC converter according to claim 1 or 2,
The control unit of the DC-DC converter, wherein the control unit sets the control low voltage value larger as the allowable voltage fluctuation range of the drive to be driven is smaller when the fluctuation range change control is executed. . In the control apparatus of the DC-DC converter of any one of Claims 1-3,
In the control unit, a first voltage rise slope and a first low voltage value are set in advance as the voltage rise slope and the control low voltage value used during the charge control, and the allowable voltage is applied to the load. A small allowable voltage fluctuation width load with a relatively small fluctuation width is set,
When the small allowable voltage fluctuation width load is driven, the control unit determines the voltage rise slope and the control low voltage value from the first voltage rise slope and the first low voltage value by the fluctuation width change control. A control device for a DC-DC converter, characterized by being changed. In the control apparatus of the DC-DC converter of any one of Claims 1-4,
The DC-DC converter control device according to claim 1, wherein the load to be driven in the fluctuation range change control is the load that is actually being driven among the plurality of loads. In the control apparatus of the DC-DC converter of any one of Claims 1-5,
The control device for a DC-DC converter, wherein the load to be driven in the fluctuation range change control is a load predicted to be driven in advance by a drive prediction unit among the plurality of loads. In the control apparatus of the DC-DC converter according to claim 6,
The drive predicting means predicts driving of the load based on information from an information acquiring means for acquiring information including at least one of map information, weather information, and time information. Control device. In the control apparatus of the DC-DC converter of Claim 6 or Claim 7,
The control unit, when the drive prediction unit predicts automatic lighting of the lighting device as the small allowable voltage fluctuation width load based on at least one of the map information and the time information from the information acquisition unit And a control device for a DC-DC converter, wherein the fluctuation range change control is executed. In the control apparatus of the DC-DC converter of any one of Claims 6-8,
The control unit performs the fluctuation range change control when the drive prediction unit predicts driving of the wiper device as the small allowable voltage fluctuation range load based on weather information from the information acquisition unit. A DC-DC converter control device. In the control apparatus of the DC-DC converter of any one of Claims 6-9,
The information from the information acquisition means includes the outside air temperature and the passenger compartment temperature,
The controller predicts driving of the air conditioner fan as the small allowable voltage fluctuation width load when the drive predicting means has a difference between the outside air temperature and the passenger compartment temperature greater than a preset set value. In this case, the control unit for the DC-DC converter performs the fluctuation range change control.