JP5203879B2 - Vehicle power supply - Google Patents

Description

  The present invention relates to a vehicular power supply device that applies a PWM (Pulse Width Modulation) -controlled voltage to a plurality of electric loads to be fed with a duty ratio according to a detected battery output voltage and a constant cycle.

In recent years, the types of electric loads mounted on vehicles and their power consumption tend to increase dramatically. Also, there is a tendency to control by electric signals without relying on mechanical connection to drive the load. For this reason, in a vehicle power supply device having a limited power source called a battery, securing power is an important issue.
In a vehicle power supply device, the output voltage of a battery is, for example, a nominal value of 12V, and an electric load is often operated at 12V. However, the output voltage of the battery is not always 12V due to its characteristics, and is used in the range of about 14V to 11.5V. For this reason, the electric load is often operated with the output voltage of the battery exceeding 12V, but wasteful power is consumed accordingly.

  In Patent Document 1, each electric load is classified into a predetermined number of groups, and the power that can be supplied from the power source is first distributed according to the priority determined for each group, and the power distributed to a certain group is distributed. A load drive control device that distributes according to the priority of each electric load is disclosed. By adopting this two-stage priority order distribution method, even if the number of electric loads and power consumption change due to vehicle variations, the priority order is changed between the electric loads belonging to the group in which this change has occurred. Just do it.

Patent Document 2 discloses a vehicle load drive control device that drives a load with large power consumption excluding an important load related to running and safety. A ratio between the connection time of the load to the battery and the disconnection time is determined according to the detected battery output voltage, and the load and the battery are connected or disconnected based on the command. The load is classified into a plurality of groups according to the connection and disconnection cycle with the battery, and the cycle is set differently for each classified group. The timing for connecting or disconnecting each load to the battery is determined from the ratio between the determined connection time and disconnection time of the load to the battery and the set cycle.
JP 2004-142661 A JP 2007-168638 A

As described above, in the vehicle power supply device, since the output voltage of the battery is used in the range of about 14V to 11.5V, the electric load is often operated with the output voltage of the battery exceeding 12V. That ’s how much power is wasted.
Therefore, recently, when the output voltage of the battery exceeds 12V, the output voltage is PWM controlled to be held at 12V and applied to each electric load. PWM control is performed with the same duty ratio. However, if the rise / fall of the voltage pulse to each electric load is aligned, the current change at the rise / fall will increase and repeat, which may cause noise, and the rise of the voltage pulse. As a result, there is a problem that a large inrush current may occur and an instantaneous voltage drop of the battery may occur.

In Patent Documents 1 and 2 described above, loads (electric loads) are divided into a plurality of groups and the instantaneous values of power consumption are distributed. However, since the total power consumption for each group is not averaged, the total power consumption If the difference is large, noise may occur, and the instantaneous voltage drop of the battery may occur.
The present invention has been made in view of the above-described circumstances. When PWM control is performed on the output voltage of the battery, noise hardly occurs at the rise / fall of the voltage pulse, and the battery voltage is increased at the rise of the voltage pulse. An object of the present invention is to provide a vehicular power supply device in which an instantaneous voltage drop hardly occurs.

  According to a first aspect of the present invention, there is provided a vehicle power supply device including: a battery; a detection unit that detects an output voltage of the battery; a duty ratio according to the output voltage detected by the detection unit; A control unit for supplying power to the electrical load to be fed, wherein the control unit calculates the number of possible off periods related to the duty ratio within the fixed period; and the power feeding Allocating means for allocating the electric load to each of the electric load groups each including one or a plurality of electric loads to be calculated and having a number equal to or less than the number calculated by the calculating means, The voltage is PWM controlled so that the off periods do not overlap each electrical load group allocated by the allocating means.

  In this vehicle power supply device, a duty ratio according to the detected output voltage of the battery and a voltage PWM-controlled by the control unit at a constant cycle are applied to a plurality of electric loads to be fed. In the control unit, the calculation unit calculates the number of off-periods related to the duty ratio that can exist within a certain period, each of which includes one or a plurality of electric loads to be fed, and is equal to or less than the number calculated by the calculation unit. The allocating means allocates the electrical load to the load group so that the difference in the total power consumption is minimized. For each electric load group allocated by the allocation means, a voltage subjected to PWM control is applied so that the off periods related to the duty ratio do not overlap.

  In the vehicular power supply apparatus according to a second aspect of the present invention, the control unit further includes means for counting the number of electrical loads to be fed as needed, and means for determining whether or not the number counted by the means has changed. And each time it is determined that the means has changed, a series of operations up to the allocating means are executed.

  In this vehicular power supply device, the control unit counts the number of electrical loads to be fed as needed, and the determination unit determines whether the counted number has changed. Each time it is determined that the determination means has changed, a series of operations up to the allocation means are executed.

  According to the vehicle power supply device of the present invention, when PWM control is performed on the output voltage of the battery, noise hardly occurs at the rise / fall of the voltage pulse, and instantaneous voltage drop of the battery hardly occurs at the rise of the voltage pulse. A vehicle power supply device can be realized.

Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof.
FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a vehicle power supply device according to the present invention.
The vehicle power supply device includes a battery B, and the battery B is charged with electric power generated by an alternator (on-vehicle generator, AC generator) 3. The alternator 3 generates power in conjunction with an engine (not shown), and the generated power is rectified and output in the alternator 3.

The power charged in the battery B and the power output from the alternator 3 are given to loads (electric loads) 1L, 2L,... NL mounted on the vehicle through the semiconductor relays 1R, 2R,. It is done.
The semiconductor relays 1R, 2R,... NR are respectively connected to the control unit 1 of the vehicle power supply device, and the control unit 1 is connected to the switches 1S, 2S,. The controller 1 individually controls on / off of the semiconductor relays 1R, 2R,... NR in accordance with the given on / off signals of the switches 1S, 2S,. Moreover, the detection means 2 which detects the output voltage of the battery B is incorporated, for example, the semiconductor relays 1R, 2R,... NR are PWM-controlled with a constant period and the same duty ratio by adjusting the power supply voltage.

The control unit 1 stores the power consumption values of the loads 1L, 2L,... NL in advance in a built-in memory. Also, the number of loads to be fed among the loads 1L, 2L,.
The control unit 1 calculates a duty ratio for PWM control of the output voltage value to 12 V based on the detected output voltage value of the battery B and its nominal value of 12 V, and the off period related to the calculated duty ratio is PWM. The number that can exist in one cycle of control is calculated. Next, loads to be fed are allocated to the calculated number of load groups or less, and PWM driving is performed with the calculated duty ratio so that the off periods of the allocated load groups do not overlap.

Hereinafter, an example of the operation of the vehicular power supply apparatus having such a configuration will be described with reference to the flowchart of FIG.
First, the control unit 1 counts the number n of loads to be supplied based on on / off signals from the switches 1S, 2S,... NS (S1), and whether or not the counted number n is zero. Is determined (S3). If the counted number n is 0, the number n of loads to be fed is repeatedly counted (S1).
If the counted number n is not 0 (S3), the control unit 1 acquires the output voltage value of the battery B detected by the detection means 2 (S5), and then calculates the average value of the acquired output voltage values. (S7). Here, the average value is, for example, a moving average value for a predetermined number of times, and absorbs sudden fluctuations in the voltage value.

Next, the control unit 1 calculates a duty ratio for PWM control of the output voltage value to 12V based on the calculated average voltage value (S7) and, for example, the nominal value 12V of the output voltage value of the battery B ( S9). The duty ratio is calculated by, for example, duty ratio = 100 × (12 / Vb) ^{2 where} the average voltage value is Vb. When the average voltage value Vb is 12 V or less, the duty ratio = 100, and the number n of loads to be fed is counted (S1).
Next, the control unit 1 calculates the number of slots q, which is the number of off periods related to the calculated duty ratio (S9) that can exist within one period of PWM control (S11). The number of slots q is calculated by, for example, q = [100 / (100−duty ratio)] (where [] is a Gaussian symbol (= floor function) and [X] is the maximum integer not exceeding X).

Next, the control unit 1 allocates n loads to be fed to g load groups (S13). When allocating n loads to the load group, the control unit 1 minimizes the difference between the total power consumption values of the load groups based on the power consumption values of the loads stored in the memory. To.
Next, the control unit 1 determines whether or not the number g of the allocated load group (S13) is equal to or less than the calculated number of slots q (S11) (S15). The number g of load groups is reduced by 1 and assigned again (S13).

If the number g of the allocated load groups (S13) is equal to or less than the calculated number of slots q (S15), the control unit 1 performs PWM driving with the calculated duty ratio (S9) for each allocated load group. Is started (S17). At that time, the control unit 1 performs PWM control on the output voltage of the battery B so that the off periods for each load group do not overlap.
As described above, for example, when the duty ratio is 64%, the output voltage of the PWM-controlled battery B applied to each load of the two load groups G1 and G2 and the total output thereof are shown in the timing chart of FIG. As shown.

When the duty ratio is 75%, the output voltage of the PWM-controlled battery B given to each load of the four load groups G3, G4, G5, and G6 and the total output thereof are shown in the timing chart of FIG. As shown. In this case, if the total power consumption value of each load group can be averaged, the change in the current output from the battery B can be minimized.
When the duty ratio is 95%, the output voltage of the PWM-controlled battery B given to each load of the four load groups G7, G8, G9, and G10 and the total output thereof are shown in the timing chart of FIG. As shown.

Next, the control unit 1 counts the number n of loads to be supplied based on the on / off signals from the switches 1S, 2S,... NS (S19), and the counted number n is counted last time. It is determined whether or not the number has changed from the determined number (S21). If the counted number n has not changed, the number n of loads to be fed is repeatedly counted (S19).
If the counted number n (S19) has changed from the previously counted number (S21), the control unit 1 determines whether the counted number n is 0 (S3).

It is a block diagram which shows schematic structure of embodiment of the vehicle power supply device which concerns on this invention. It is a flowchart which shows the example of operation | movement of the vehicle power supply device which concerns on this invention. It is a timing chart which shows the example of operation | movement of the vehicle power supply device which concerns on this invention. It is a timing chart which shows the example of operation | movement of the vehicle power supply device which concerns on this invention. It is a timing chart which shows the example of operation | movement of the vehicle power supply device which concerns on this invention.

Explanation of symbols

1 Control unit (calculation means, allocation means)
2 Detection means 3 Alternator (on-vehicle generator, AC generator)
1L, 2L, ... NL load (electric load)
1R, 2R, ... NR Semiconductor relay 1S, 2S, ... NS Switch B Battery

Claims (2)

A battery, detection means for detecting the output voltage of the battery, and a control unit for applying a duty ratio corresponding to the output voltage detected by the detection means and a voltage subjected to PWM control at a constant cycle to a plurality of electric loads to be fed In a vehicle power supply device comprising:
The control unit includes a calculation unit that calculates the number of off-periods related to the duty ratio that can exist within the fixed period, and one or more of the electrical loads to be supplied, and the number calculated by the calculation unit The electrical load group is provided with allocation means for allocating the electrical load so that the difference in total power consumption is minimized, and the off-period is assigned to each electrical load group allocated by the allocation means. A power supply device for a vehicle, characterized in that a voltage subjected to PWM control is applied so as not to overlap.   The control unit further includes means for counting the number of electrical loads to be fed as needed, and means for determining whether the number counted by the means has changed, each time it is determined that the means has changed. The vehicle power supply device according to claim 1, configured to execute a series of operations up to the allocating means.

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