JP4070113B2 - Power supply device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power supply device for supplying power to an auxiliary machine from an auxiliary power supply unit in place of the main power supply unit in an emergency such as an abnormality of the main power supply unit to guarantee the operation of the auxiliary machine.
[0002]
[Prior art]
In recent years, with the enforcement of the PL Act (Product Liability Act), efforts and standards creation for safe driving of vehicles have been regarded as important. As a safety measure, for example, an emergency call device called a Mayday system has been introduced in the past. In this device, if the power generation capacity of the vehicle, the storage battery, the power line, etc. are lost, the power supply capacity is lost. In some cases, an auxiliary power supply is used instead of the main power supply to guarantee the operation of the emergency call device.
[0003]
In addition, in order to ensure safe operation of vehicles, electronic control systems using technology called by-wire technology will be used for the control of traveling systems such as engines, brakes, and steering. Technology for avoiding accidents by supplying power from an auxiliary power supply is becoming important.
[0004]
Examples of the power source used for the auxiliary power supply unit include a storage battery and a capacitor, but the storage battery is excellent in terms of the cost ratio of the discharge performance. Furthermore, among these power supplies, lead-acid batteries are the most excellent in discharge characteristics in a very low temperature state of −30 ° C. to −40 ° C. in consideration of the external environmental conditions of the earth. For this reason, lead storage batteries have been used as an auxiliary power supply in the emergency call device described above. As such an auxiliary power supply device, for example, there is one as shown in Patent Document 1.
[0005]
[Patent Document 1]
JP-A-5-244704 (page 2-3, FIG. 1)
[0006]
[Problems to be solved by the invention]
However, the lead storage battery has inferior discharge performance per volume or weight compared to other storage batteries and capacitors, and in order to increase this discharge performance, as a result, it leads to an increase in size and weight. Become. That is, for example, the power supply voltage of a vehicle used with a 12V battery is regulated within the range shown in FIG. 7, and in the region of 10V or less, the operation of the auxiliary system is not guaranteed due to insufficient voltage, In the region of 16V or more, the withstand voltage of auxiliary machine parts is exceeded. Therefore, from this, the power supply voltage of the vehicle is set to a proper allowable range of 10V to 16V.
[0007]
When the output voltage characteristics of a general 12V lead acid battery (6-cell configuration) used in this vehicle are schematically shown, the relationship shown in FIG. 8 is established, and the current required for the operation of the auxiliary machine A value is chosen that ensures a voltage of 10V or more for the required time. In this figure, when normal discharge is applied, the voltage of the 12V battery instantaneously increases to the maximum voltage of about 13.2V, and thereafter, the voltage gradually decreases. This phenomenon occurs when the current flowing at the time of discharge is small or the capacity of the storage battery is the one-dot chain line A, and this voltage is high, and when the current flowing at the time of discharging is large or the capacity of the storage battery is the one-dot chain line B This voltage is low.
[0008]
Therefore, there is still room for the auxiliary withstand voltage upper limit 16V shown in FIG. However, in the case of the one-dot chain line B shown in FIG. 8, there is a case where the auxiliary machine operation guarantee lower limit value of 10V falls below this, and the auxiliary machine operation limit may not be reached. For this reason, when the current is fixed, it is necessary to increase the capacity of the storage battery and increase the voltage of the battery, resulting in an increase in the size and weight of the power supply device. There was a problem that it would affect the installation space and weight.
[0009]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a power supply device that can reduce the volume and weight of a storage battery and reduce the overall size and weight of the device.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, in the power supply apparatus according to claim 1, in the power supply apparatus having a main power supply unit that supplies power to the auxiliary machine and operates the auxiliary machine, the power supply apparatus is larger than the voltage of the main power supply unit. And an auxiliary power supply that supplies a voltage that is less than or equal to the upper limit voltage of the continuous rating of the auxiliary machine, and a switching means that switches the voltage supplied from the main power supply and the auxiliary power supply and supplies the auxiliary machine to the auxiliary machine. A power supply device is provided.
[0011]
According to the first aspect of the present invention, the voltage supplied from the auxiliary power supply unit is set to be greater than the voltage of the main power supply unit (eg, 13.2V) and lower than the upper limit voltage (eg, 16V) of the continuous rating of the auxiliary machine. By doing so, the volume and weight of the storage battery are reduced.
[0012]
Moreover, in the power supply device according to claim 2, the auxiliary power supply unit has a storage battery having a predetermined number of cells, and the storage battery is larger than a voltage of the main power supply unit and is not more than an upper limit voltage of a continuous rating of the auxiliary machine. And charging means for charging to a voltage.
[0013]
According to the second aspect of the present invention, when the storage battery charging means (charging circuit) is provided, charging is performed by charging the storage battery of the auxiliary power supply unit with a voltage within the range set in the first aspect. The current is reduced, and the charging circuit is reduced in size and cost.
[0014]
Further, in the power supply device according to claim 3, the auxiliary power supply unit further includes a detection unit that measures an internal resistance value of the storage battery and detects a deterioration state of the storage battery based on the measurement result. Features.
[0015]
According to the third aspect of the present invention, for example, the internal resistance of the battery that has been increased due to the increase in the number of cells is obtained, and the deterioration state of the battery is accurately detected based on the internal resistance value.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
A preferred embodiment of a power supply apparatus according to the present invention will be described with reference to the accompanying drawings in FIGS.
[0017]
(Embodiment 1)
FIG. 1 is a configuration diagram showing an example of a configuration of a power supply device according to the present invention. In the figure, a main power supply unit 10 includes a generator 11, a battery 12, and fuses 13 to 15, and power lines 16 and 17 from the generator 11 and battery 12 are connected to a main power supply line 18 via fuses 13 and 14, respectively. The main power line 18 is connected to the auxiliary machine 31 via the power switching circuit 30. Therefore, power is supplied to the auxiliary machine 31 from the generator 11 and the battery 12 through the main power line 18 at normal times.
[0018]
The auxiliary power supply unit 20 includes a charging circuit 21 and an auxiliary battery 22, and the charging circuit 21 is connected to the battery 12 via the power line 19, and charges the auxiliary battery 22 with power supplied from the battery 12 at normal times. It is carried out. The battery 22 is connected to the auxiliary machine 31 via the power supply switching circuit 30. In an emergency such as an abnormality of the main power supply unit 10, the power supply switching circuit 30 is switched, and power is supplied from the battery 22 to the auxiliary machine 31. In addition, each battery 12 and 22 of the main power supply part 10 and the auxiliary power supply part 20 is comprised, for example from the lead acid battery, and the 12V lead acid battery of the general main power supply part 10 used with a vehicle is 6 cell structure. It has become.
[0019]
The inventors of the present invention performed the following verification on the power supply device having such a configuration. That is, as shown in FIG. 2, in a lead storage battery, the battery capacity at which the minimum voltage for 10 seconds was 10 V or more during 25 A discharge was determined in relation to the number of cells. As a result, the capacity decreases rapidly from 50 Ah to 3.6 Ah between 5 cells and 6 cells, but from 6 cells, 7 cells are 1.9 Ah, 8 cells are 1.3 Ah, and 9 cells are 1.1 Ah. It turns out that it decreases gradually.
[0020]
Furthermore, from this relationship, the volume ratio when the required performance is satisfied in each cell configuration is shown in FIG. 3, and the weight ratio is shown in FIG. Here, the volume ratio is 100% in the case of 6 cells, about 67% in the case of 7 cells, about 55% in the case of 8 cells, and more than 9 cells from the case of 8 cells. It was decreasing slowly. The weight ratio is 100% in the case of 6 cells, about 55% in the case of 7 cells, about 38% in the case of 8 cells, and more than 9 cells is gradually reduced from the case of 8 cells. Was.
[0021]
From these relationships, it was found that when the lead storage battery has a 7-cell configuration as compared to the 6-cell configuration, the volume ratio is greatly improved to about 2/3 and the weight ratio to about 1/2. Further, in the case of the 8-cell or 9-cell configuration, the improvement is further improved, but the improvement rate becomes small.
[0022]
Also, FIG. 5 shows the output voltage range in each cell configuration. As is apparent from this figure, those having an 8-cell configuration or more exceed the existing auxiliary device withstand voltage upper limit 16V, Not only does the system need to be completely redesigned, but it also increases costs due to increased component ratings. As a result, the overall cost of the vehicle is higher than that of a typical 6-cell lead acid battery. I understood that
[0023]
Therefore, in this embodiment, in consideration of the detection results described above, the battery (lead storage battery) 22 of the auxiliary power supply unit 20 is one more than the 6-cell configuration of the battery 12 of the main power supply unit 10, To do. Further, in this embodiment, the voltage supplied from the battery 22 is larger than the voltage supplied from the battery 12 of the main power supply unit 10 (for example, the maximum voltage 13.2 V in the case of the 6-cell configuration), and the auxiliary machine The upper limit voltage of the continuous rating (for example, auxiliary machine withstand voltage upper limit value 16V) is set below.
[0024]
Thus, in this embodiment, the auxiliary power storage battery has a 7-cell configuration, one more than the number of main power storage batteries, and the voltage supplied from the auxiliary power storage battery is the main power supply unit. Is set to be larger than the voltage supplied from the storage battery and less than or equal to the auxiliary withstand voltage upper limit value, the volume and weight of the storage battery can be reduced as shown in FIG. 3 and FIG. Can be reduced in size and weight.
[0025]
In addition, in the auxiliary power supply unit 20 according to this embodiment, the charging circuit 21 of the battery 22 causes the voltage supplied from the battery 22 to be higher than the voltage supplied from the battery 12 of the main power supply unit 10 with this setting. The battery 22 of the auxiliary power supply unit 20 is charged so as to be large and less than or equal to the auxiliary device withstand voltage upper limit value.
[0026]
Here, in the case of a single cell capacity value for guaranteeing an output voltage of 10 V in each cell number shown in FIG. 2, if the vehicle is left at an average temperature of 40 ° C. for one month, the self-discharge during that time is approximately 10%. The time t required to fully charge with a constant current charger with 1A as the upper limit of the charging current is 5 cells, and the self-discharge amount 10% is 50 Ah × 10% = 5 Ah. If the efficiency is 90%, t = 5 Ah / (1 A / 90%) = 5.6 hours.
[0027]
Similarly, in the case of 6 cells, the self-discharge amount 10% is 3.6 Ah × 10% = 0.36 Ah, and the time until full charge t = 0.36 Ah / (1 A / 90%) = 0.4 In the case of 7 cells, the self-discharge amount 10% is 1.9 Ah × 10% = 0.19 Ah, and the time until full charge t = 0.19 Ah / (1 A / 90%) = 0.21 hours In the case of 8 cells, the self-discharge amount 10% is 1.3 Ah × 10% = 0.13 Ah, the time until full charge t = 0.13 Ah / (1 A / 90%) = 0.14 hours, In the case of 9 cells, 1.1 Ah × 10% = 0.11 Ah, and the time to full charge t = 0.11 Ah / (1 A / 90%) = 0.12 hours.
[0028]
However, if charging is performed at 1A with 7 cells, the capacity ratio is 0.53C. Usually, the upper limit of the charging current is usually suppressed to 0.2 to 0.3 C in order to prevent deterioration of the battery. Here, assuming that the capacity ratio is 0.3C, in 7 cells, 1.9Ah × 0.3C = 0.57A is 0.33 hours, and similarly in 8 cells and 9 cells, it is 0.33 hours. The charging time will not change.
[0029]
Thus, in this embodiment, the auxiliary power storage battery has a seven-cell configuration, and the voltage supplied from the auxiliary power storage battery is larger than the voltage supplied from the main power storage battery, and the auxiliary machine. Since the battery is charged so that the withstand voltage value is below the upper limit of the withstand voltage, the charging time is shortened and charging is possible even with a short running time of the vehicle.For example, the amount of electricity required for the battery of the auxiliary power supply unit during warm-up It becomes possible to replenish quickly, and always ensure emergency power.
[0030]
Further, in this embodiment, the self-discharge amount and the battery capacity are in a proportional relationship, and if the capacity of the storage battery is reduced by increasing the number of cells, the charging current can be reduced, so that the charging circuit is reduced in size and cost. be able to.
[0031]
In this embodiment, the case where the battery of the main power supply unit is a 12V battery has been described. However, the present invention is not limited to this, and for example, the above-described setting is possible even when the battery of the main power supply unit is a 24V battery or a 36V battery. Auxiliary power supply according to the same setting condition as the condition that the voltage supplied from the storage battery for the auxiliary power supply is set to be larger than the voltage supplied from the storage battery of the main power supply unit and not more than the auxiliary device withstand voltage upper limit value. By configuring the part battery, it is possible to obtain the same effects as those of the first embodiment described above.
[0032]
(Embodiment 2)
FIG. 6 is a block diagram showing another example of the configuration of the power supply device according to the present invention. 1 is different from the configuration of the first embodiment in FIG. 1 in that a battery state detection circuit 23 is provided in the auxiliary power supply unit 20 to detect a battery deterioration state of the battery 22.
[0033]
The battery state detection circuit 23 detects the deterioration state of the battery by measuring the impedance of the battery 22 which is a lead storage battery, for example, the internal resistance value of the battery. The battery state detection circuit 23 includes a constant current discharge circuit and a battery voltage measurement circuit. It is configured. Next, a method for measuring the internal resistance value of the battery by the battery state detection circuit 23 will be described.
[0034]
Here, the discharge current is I, the internal resistance value of the whole battery incorporated in the auxiliary power supply unit R is R (R6 is a 6-cell configuration, R7 is a 7-cell configuration), and the voltage change during constant current discharge is When ΔV, the internal resistance value of the unit cell is r, and the capacity of the unit cell (the capacity of the built-in battery) is Ah,
Internal resistance value R = ΔV / I (1)
More demanded. Here, if the minimum voltage for 10 seconds is guaranteed to be 10 V or more during 25 A discharge, the battery capacity is about 3.6 Ah in the 6-cell configuration, and the measured R is about 100 mΩ. If this is a 7-cell configuration, the battery capacity is 1.9 Ah, and the internal resistance value is approximately inversely proportional to the capacity, so R is approximately doubled.
[0035]
That means
R6 = r6 × 6 (2)
r7 = r6 × 1.9 (3)
R7 = r7 × 7 (4)
From the equations (2) and (3), the internal resistance value r7 of the unit cell in 7 cells is
r7 = R6 × (1.9 / 6) (5)
When substituting this equation (5) into equation (4),
R7 = R6 × (1.9 / 6) × 7 = R6 × 2.2
It becomes. As is apparent from this calculation result, for example, when measured at the same discharge current value I, the voltage change ΔV during the constant current discharge in the case of 7 cells from the equation (1) is the constant current discharge in the case of 6 cells. It becomes 2.2 times the voltage change at the time.
[0036]
Thus, in this embodiment, the internal resistance value of the battery of the auxiliary power supply unit in the 7-cell configuration is 2.2 times the internal resistance value of the battery of the auxiliary power supply unit in the 6-cell configuration, and is proportional to this. Since the voltage change is also 2.2 times, it is less affected by noise and the measurement accuracy is increased. Accordingly, it is possible to accurately detect battery deterioration.
[0037]
In this embodiment, when the voltage change to be measured can be the same amount of change in the 6-cell configuration and the 7-cell configuration, the discharge current value I can be halved in the case of the 7-cell configuration. The circuit can be reduced in size and weight.
[0038]
The present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the present invention.
[0039]
【The invention's effect】
As described above, in the present invention, the voltage supplied from the auxiliary power supply unit is set to be larger than the voltage supplied from the main power supply unit and lower than the upper limit voltage of the continuous rating of the auxiliary machine. The weight can be reduced, and the entire apparatus can be reduced in size and weight.
[0040]
In the present invention, when a storage battery charging circuit is provided, the capacity of the storage battery is reduced due to the increase in the number of cells, and the storage battery of the auxiliary power supply unit is charged with a voltage within the range set in claim 1. The charging current is reduced, and the charging circuit can be reduced in size and cost.
[0041]
In addition, in the present invention, the increase in the number of cells increases the internal resistance of the battery, and the voltage change increases in proportion to this, so that it is less susceptible to noise and the measurement accuracy is increased. It becomes possible to detect deterioration with high accuracy.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an example of a configuration of a power supply device according to the present invention.
FIG. 2 is a relationship diagram showing a single cell capacity value for guaranteeing an output voltage of 10 V in each cell number.
FIG. 3 is a relationship diagram showing a volume ratio according to each cell configuration.
FIG. 4 is a relationship diagram showing a weight ratio according to each cell configuration.
FIG. 5 is a relationship diagram showing an output voltage range in each cell configuration.
FIG. 6 is a configuration diagram showing another example of the configuration of the power supply device according to the present invention.
FIG. 7 is a diagram showing an appropriate range of a power supply voltage of a vehicle used with a 12V battery.
FIG. 8 is a diagram showing discharge voltage characteristics of a storage battery.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Main power supply part 11 Generator 12, 22 Battery 13-15 Fuse 16, 17, 19 Power supply line 18 Main power supply line 20 Auxiliary power supply part 21 Charging circuit 23 Battery state detection circuit 30 Power supply switching circuit 31 Auxiliary machine I Discharge current value R Internal resistance value r Internal resistance value t Time ΔV Voltage change

Claims (3)

In a power supply device having a main power supply unit for supplying power to an auxiliary machine and operating the auxiliary machine,
An auxiliary power supply unit that supplies an internal resistance value larger than the internal resistance value of the main power supply unit, greater than the voltage of the main power supply unit, and less than or equal to the upper limit voltage of the continuous rating of the auxiliary machine;
Switching means for switching the voltage supplied from the main power supply unit and the auxiliary power supply unit to supply to the auxiliary machine,
A power supply device comprising: The auxiliary power unit is
A storage battery having more cells than the number of cells of the main power supply unit ;
Charging means for charging the storage battery to a voltage that is greater than the voltage of the main power supply unit and not more than the upper limit voltage of the continuous rating of the auxiliary machine;
Power supply device according to claim 1, further comprising a. The auxiliary power unit is
The power supply apparatus according to claim 2, further comprising a detecting unit that measures an internal resistance value of the storage battery and detects a deterioration state of the storage battery based on the measurement result.

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