JP7340775B2 - Vehicle power system - Google Patents

Description

The present invention relates to an on-vehicle power supply system used in various vehicles.

Hereinafter, a conventional vehicle-mounted power supply 1 will be explained using the drawings. FIG. 9 is a circuit block diagram showing the configuration of a conventional in-vehicle power source 1. The in-vehicle power source 1 had a charging circuit 2, a storage battery 3, and a discharging circuit 4. Here, when the vehicle battery 5 is in a normal state, the electric power supplied from the vehicle battery 5 is stored in the storage battery 3 by the charging circuit 2, and the electric power stored in the storage battery 3 is transferred to the discharge circuit 4 as needed. was supplied to load 6 by. On the other hand, when the vehicle battery 5 is in an abnormal state, the charging circuit 2 is stopped and the electric power stored in the storage battery 3 is transferred through the discharging circuit 4, which operates according to instructions from a control circuit (not shown). It was supplied from the storage battery 3 to the load 6.

Note that, as prior art document information related to the invention of this application, for example, Patent Document 1 is known.

International Publication No. 2013/125170

However, especially when the discharge circuit 4 performs a step-up operation to supply power from the storage battery 3 to the load 6, when the vehicle battery 5 is in an abnormal state and the power supply to the storage battery 3 is cut off, the storage battery 3 is discharged. When the voltage of the storage battery 3 decreases and becomes lower than a predetermined voltage, the discharge circuit 4 is no longer able to boost the voltage, and the on-vehicle power supply 1 is no longer able to supply power to the load 6.

In other words, the on-vehicle power supply 1 has a problem in that it is unable to fully output the power of the storage battery 3 and stops operating with a predetermined amount of power remaining in the storage battery 3.

Therefore, an object of the present invention is to efficiently utilize the electric power stored in the power storage unit.

In order to achieve this object, the present invention includes an input part, an output part, a conductive line part connecting the input part and the output part, a high potential electrode and a low potential electrode, a power storage unit to which the conductive line portion is connected to a high potential electrode; a variable voltage unit connected between the low potential electrode and ground; and a voltage variable unit connected to the power storage unit and the variable voltage unit. a control unit configured to control a value obtained by adding the voltage of the variable voltage unit to the potential difference between the high potential electrode and the low potential electrode to a predetermined constant value during a discharge period of the power storage unit. The present invention is characterized in that the voltage of the variable voltage section is controlled so as to set the value.

According to the present invention, when discharging power from the power storage unit in a situation where there is little remaining power in the power storage unit and the voltage of the power storage unit is decreasing, the voltage of the variable voltage unit is superimposed on the voltage of the power storage unit. By doing so, it is possible to output a voltage higher than the voltage of the power storage unit from the output unit to the outside.
There is no need for the voltage of the power storage unit to be higher than the voltage that can be boosted. Therefore, even when there is little remaining power in the power storage unit and the voltage of the power storage unit is low, power can continue to be discharged from the power storage unit, and the power stored in the power storage unit can be used efficiently. .

A first circuit block diagram showing the configuration of an on-vehicle power supply system according to an embodiment of the present invention A second circuit block diagram showing the configuration of the in-vehicle power supply system according to the embodiment of the present invention First operation timing chart of the on-vehicle power supply system according to the embodiment of the present invention Third circuit block diagram showing the configuration of the on-vehicle power supply system according to the embodiment of the present invention Second operation timing chart of the on-vehicle power supply system according to the embodiment of the present invention Fourth circuit block diagram showing the configuration of the on-vehicle power supply system according to the embodiment of the present invention Fifth circuit block diagram showing the configuration of the on-vehicle power supply system according to the embodiment of the present invention Sixth circuit block diagram showing the configuration of the on-vehicle power supply system according to the embodiment of the present invention Circuit block diagram showing the configuration of a conventional in-vehicle power supply

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment)
FIG. 1 is a circuit block diagram showing the configuration of an on-vehicle power supply system 7 in an embodiment of the present invention. The on-vehicle power supply system 7 includes an input section 8 , an output section 9 , a conductive line section 10 , a power storage section 11 , a variable voltage section 12 , and a control section 13 . The conductive line section 10 connects the input section 8 and the output section 9. Power storage unit 11 has a high potential electrode 11A and a low potential electrode 11B. High potential electrode 11A of power storage section 11 is connected to conductive line section 10. Variable voltage section 12 is connected to low potential electrode 11B of power storage section 11 and ground G. Control section 13 is connected to power storage section 11 and variable voltage section 12 . Further, the control section 13 controls the operation of the variable voltage section 12.

The control unit 13 sets a value obtained by adding the voltage of the variable voltage unit 12 to the potential difference between the high potential electrode 11A and the low potential electrode 11B of the power storage unit 11 to a predetermined constant value during the discharge period of the power storage unit 11. The voltage of the variable voltage section 12 is controlled.

With the above configuration and operation, the on-vehicle power supply system 7 can discharge and output most of the power stored in the power storage unit 11, especially during the discharge period, so the power stored in the power storage unit 11 can be used efficiently. be done. The in-vehicle power supply system 7 operates even in situations where there is little power remaining in the power storage unit 11 and the voltage of the power storage unit 11 is decreasing, or when there is a large amount of power remaining in the power storage unit 11 and the voltage of the power storage unit 11 is close to full charge. Even under such circumstances, when discharging power from power storage unit 11 , a predetermined voltage can be output without providing a boost converter between power storage unit 11 and output unit 9 . When discharging power from the power storage unit 11, the in-vehicle power supply system 7 superimposes the voltage of the variable voltage unit 12 on the voltage of the power storage unit 11 to generate a predetermined constant value that is a voltage higher than the voltage of the power storage unit 11. can be output from the output section 9 to the outside. Therefore, the voltage of power storage unit 11 does not need to be higher than a voltage that can be boosted. Therefore, even under a situation where there is little power remaining in the power storage unit 11 and the potential difference of the power storage unit 11 is small, the power stored in the power storage unit 11 can continue to be discharged, and the in-vehicle power supply system 7 The power stored in the system can be used efficiently. In other words, the on-vehicle power supply system 7 can output a large amount of power over a long period of time.

Below, the circuit block diagram of FIG. 1, the second circuit block diagram showing the configuration of the in-vehicle power supply system 7 in the embodiment of the present invention in FIG. The configuration and operation of the vehicle-mounted power supply system 7 will be described in detail using a first operation timing chart. As described above, the on-vehicle power supply system 7 includes the input section 8 , the output section 9 , the conductive line section 10 , the power storage section 11 , the variable voltage section 12 , and the control section 13 .

The input unit 8 is connected to the vehicle battery 14 , the vehicle power supply system 7 receives power from the vehicle battery 14 , and the power storage unit 11 is charged by the power from the vehicle battery 14 . Although not shown here, the on-vehicle power supply system 7 may receive power from a generator together with the vehicle battery 14.

The output unit 9 is connected to a vehicle load 15 , and the vehicle-mounted power supply system 7 drives the vehicle load 15 by discharging the electric power stored in the power storage unit 11 . Further, the vehicle load 15 may start driving when it receives power from the on-vehicle power supply system 7, or may receive power from the on-vehicle power supply system 7 and then operate a switch provided inside the vehicle load 15. Driving may be started when both conditions are met by closing a container (not shown), or at any time.

Although not shown, the input section 8 and the output section 9 do not need to have a configuration with a specific function, and may be terminals that can be electrically connected using a fixture, welding, etc., or welding, etc. It may be a conductor that can be connected with

The conductive line section 10 connects the input section 8 and the output section 9. The conductive line portion 10 may be provided as a wiring pattern on a wiring board (not shown) of the on-vehicle power supply system 7, or may be provided as a cable or a bus bar in the form of a copper plate. In either case, a large current flows through the conductive line portion 10 during charging and discharging. For this reason, it is desirable that the conductive line portion 10 is a conductor having a large cross-sectional area in the direction of current flow and a large current capacity.

The power storage unit 11 has a high potential electrode 11A and a low potential electrode 11B, and the high potential electrode 11A is connected to the conductive line portion 10 at a connection point 16. The power storage element itself may be the power storage unit 11. Although not shown here, the power storage unit 11 may also include a power storage element, a protection circuit or a control circuit dedicated to the power storage unit 11, a discharge circuit for discharging surplus power of the power storage element, and the like. Further, the power storage element of the power storage unit 11 may be a chemical secondary battery such as a lead battery or a lithium ion battery, or a capacitor secondary battery such as an electric double layer capacitor.

As mentioned earlier, in the vehicle power supply system 7, the voltage of the power storage unit 11 decreases as the electric power remaining in the power storage unit 11 decreases and the potential difference between both ends of the power storage unit 11 decreases. It is possible to continue discharging power from power storage unit 11 even under conditions inappropriate for boosting the voltage. Therefore, by using a capacitor secondary battery as the power storage element applied to the power storage unit 11 of the vehicle-mounted power supply system 7, the vehicle-mounted power supply system 7 can operate effectively. This is because, in contrast to chemical secondary batteries, where the remaining amount of charge decreases rapidly after a long period of discharge, capacitor secondary batteries have a rate of decrease in the amount of remaining charge that is roughly similar to that depending on the discharge time. This is because the voltage will reach a state of insufficient voltage at an early point in time to increase the voltage.

Variable voltage section 12 is connected to low potential electrode 11B of power storage section 11 and ground G. Further, the high potential electrode 12A of the variable voltage section 12 is connected to the low potential electrode 11B of the power storage section 11, and the variable voltage section 12
A low potential electrode 12B is connected to ground G. Since power storage unit 11 and variable voltage unit 12 are connected in series, variable voltage unit 12 superimposes a variable DC voltage on the DC voltage of power storage unit 11 .

Control section 13 is connected to power storage section 11 and variable voltage section 12 . Strictly speaking, control section 13 detects the voltage of high potential electrode 11A of power storage section 11, and furthermore, control section 13 detects the voltage of low potential electrode 11B of power storage section 11. Furthermore, the control section 13 may detect the voltage on the high potential side of the variable voltage section 12. The voltage on the high potential side of variable voltage section 12 has approximately the same value as the voltage on low potential electrode 11B of power storage section 11. Furthermore, the control section 13 detects the voltages of the input section 8 and the output section 9. The control section 13 then controls the operation of the variable voltage section 12.

First, the control related to charging and the control related to discharging in the control unit 13 will be explained. Control of the variable voltage section 12 by the control section 13 is divided into a stop period, a charging period, a sustaining period, and a discharging period. The stop period is a state before the external signal receiving section 17 connected to the control section 13 receives the vehicle activation signal SIG1. The vehicle activation signal SIG1 is a signal issued from a control device (not shown) of the vehicle 18 on which the on-vehicle power supply system 7 is mounted when the vehicle 18 is activated. Further, when the vehicle 18 is started, the interlocking switch 19, which was in the disconnected state before starting, is switched to the connected state. In the timing chart, the vehicle starting signal SIG1 is OFF before the external signal receiving section 17 receives the vehicle starting signal SIG1, and the vehicle starting signal SIG1 is ON before the external signal receiving section 17 receives the vehicle starting signal SIG1. are shown respectively.

During the stop period, although the terminal voltage VB exists in the vehicle battery 14, the input unit 8 does not detect the terminal voltage VB of the vehicle battery 14 because the interlocking switch 19 is in the cut-off state. At this time, since voltage is being applied from the vehicle battery 14 to the vehicle load 15 via the normal route section 20, the terminal voltage VB of the vehicle battery 14 is detected at the output section 9. Actually, since the rectifying element 21 is connected to the normal line section 20, a voltage drop occurs due to the rectifying element 21, and the voltage detected at the output section 9 has a value lower than VB.

Further, during the stop period, the first potential difference VD, which is the potential difference between the high potential electrode 11A and the low potential electrode 11B of the power storage unit 11, is controlled to approximately the basic voltage VD1. In particular, when the power storage element applied to the power storage unit 11 is an electric double layer capacitor, the basic voltage VD1 should be kept low to a level that prevents deterioration of the electric double layer capacitor in a long-term charging state. is desirable. Further, in order to shorten the charging time during the charging period described later, it is desirable that the basic voltage VD1 is at a level at which deterioration of the electric double layer capacitor is difficult to progress and is equal to or higher than a predetermined value.

Furthermore, during the stop period, the second potential difference, which is the potential difference between the high potential electrode 12A and the low potential electrode 12B of the variable voltage section 12, is zero. The control unit 13 may detect the voltage between the high potential electrode 12A and the low potential electrode 12B of the variable voltage unit 12, but the high potential electrode 12A of the variable voltage unit 12 may detect the voltage between the high potential electrode 12A and the low potential electrode 11B of the power storage unit 11. Since they are at the same potential, the voltage of low potential electrode 11B of power storage unit 11 may be substituted. Further, since the low potential electrode 12B of the variable voltage section 12 is grounded, the second potential difference may be the voltage of the low potential electrode 11B of the power storage section 11.

Next, the charging period will be explained. During the charging period, since the interlocking switch 19 is switched from the disconnected state to the connected state at time T1 when the charging period starts, the terminal voltage VB of the vehicle battery 14 is detected as is at the input section 8. Then, the power storage unit 11 is charged using the terminal voltage VB of the vehicle battery 14.

Before the charging period starts, in other words, during the stop period, the first potential difference VD of the power storage unit 11 is the base voltage VD1, but during the charging period, the first potential difference VD of the power storage unit 11 is increased from the base voltage VD1 to the set voltage VD2. It will be done. Set voltage VD2 roughly corresponds to the full charge voltage of power storage unit 11, or corresponds to a value that is lower than the full charge voltage of power storage unit 11 and does not cause overcharging. The preset voltage VD2 is the upper limit of the range in which the terminal voltage VB of the vehicle battery 14 can be set. Therefore, the rated voltage of the power storage element of the power storage unit 11 needs to be higher than the rated voltage of the vehicle battery 14. Furthermore, the set voltage VD2 is a voltage value that is greater than or equal to the voltage value that can drive the vehicle load 15.

Also at this time, voltage is being applied from the vehicle battery 14 to the vehicle load 15 via the normal line section 20, so the output section 9 detects the terminal voltage VB of the vehicle battery 14. Actually, since the rectifying element 21 is connected to the normal line section 20, a voltage drop occurs due to the rectifying element 21, and the voltage detected at the output section 9 has a value lower than VB.

During the charging period, even if the power storage unit 11 is charged by changing the second potential difference VI of the variable voltage unit 12 according to the charging current flowing to the power storage unit 11 by the control unit 13, or the second potential difference VI of the variable voltage unit 12 is changed. VI may be fixed at zero and power storage unit 11 may be charged by terminal voltage VB of vehicle battery 14 itself. In other words, the control unit 13 controls the charging current flowing to the power storage unit 11 and the time required from time T1 to time T2, which is the charging period, based on the second potential difference VI of the variable voltage unit 12.

In the timing chart, as an example, the second potential difference VI of the variable voltage section 12, which was zero until then, is switched to the initial potential difference VI1 at time T1 and increases. Then, it is gradually decreased until the time point T2 when the charging period ends. The second potential difference VI may be reduced linearly or curved as shown in the timing chart, or may be reduced stepwise by intermittent switching control. For example, when the power storage element applied to the power storage unit 11 is an electric double layer capacitor, by setting the second potential difference VI to the initial potential difference VI1 at the time of T1, the amount of accumulated charge is small and a large current flows. What is necessary is to suppress the current flowing through the electric double layer capacitor in a state where it is easy.

Here, the value of the initial potential difference VI1 may be set as the difference between the aforementioned set voltage VD2 and the basic voltage VD1. In other words, the control section 13 controls the variable voltage section 12 so that the value obtained by adding the initial potential difference VI1 to the basic voltage VD1 becomes the set voltage VD2. During the charging period, the first potential difference VD increases as charging progresses, the second potential difference VI decreases in response to the increase in the first potential difference VD, and the second potential difference VI is added to the first potential difference VD. The control section 13 controls the variable voltage section 12 so that the added value becomes the set voltage VD2. That is, during the charging period, the control unit 13 controls the variable voltage unit 12 by setting the value obtained by adding the second potential difference VI to the first potential difference VD as a constant value of the set voltage VD2. Thereby, control section 13 can control the charging state of power storage section 11 by controlling second potential difference VI of variable voltage section 12 .

Here, since the upper limit of the set voltage VD2 is the terminal voltage VB of the vehicle battery 14, the second potential difference VI is always a value lower than the terminal voltage VB of the vehicle battery 14. For this reason, the variable voltage section 12 that generates the second potential difference VI is connected to the output section 9 by the power supply path 12P, and during the charging period, it also functions as a step-down converter that generates the second potential difference VI using the voltage of the output section 9. good. Buck converters have high power conversion efficiency. In the above operation, since the variable voltage section 12 is provided to cause voltage changes, power consumption in the variable voltage section 12 is very small. Therefore, even if the variable voltage section 12 is a step-down converter that operates using the voltage of the output section 9, the influence on the output section 9 and the vehicle load 15 can be kept very small. Further, the set voltage VD2 may be set to a value lower than the terminal voltage VB of the vehicle battery 14 during normal operation. As a result, as long as the vehicle battery 14 is outputting the terminal voltage VB, the power stored in the power storage unit 11 will not be discharged, and the in-vehicle power supply system 7 will store a large amount of power in the power storage unit 11 for a long time. can be maintained over a period of time.

Here, when a step-down converter is used as the variable voltage section 12, as shown in the third circuit block diagram showing the configuration of the on-vehicle power supply system in the embodiment of the present invention in FIG. It has a switching element 24 and a choke coil 25 connected in series from the output part 9 side between the output part 9 and the low potential electrode 11B of the power storage part 11, and further includes a smoothing capacitor 27 and a rectifying element 28. It is enough if you have it. The smoothing capacitor 27 is connected between the connection point 26 between the choke coil 25 and the low potential electrode 11B and the ground G, and the rectifying element 28 has a cathode connected to the connection point 29 between the switching element 24 and the choke coil 25. An anode is connected and arranged to ground G. In addition, in order to connect the switching element 24 and supply power from the output section 9 to the choke coil 25, or to cut off the switching element 24 and stop supplying power from the output section 9 to the choke coil 25, Although the driver 30 that drives the switching element 24 to open and close is provided in the variable voltage section 12 so as to be controlled by the control section 13, the driver 30 may be included in the control section 13. do not have. Further, the switching element 24 may be a semiconductor switch such as a FET (field effect transistor).

Next, the maintenance period will be explained. During the maintenance period, the state of power supply from the vehicle battery 14, the voltage detected at the input section 8 and the output section 9, etc. do not change from the charging period. At time T2 when the maintenance period begins, the operation related to charging the power storage unit 11 has basically ended. Therefore, the control unit 13 performs less control over the variable voltage unit 12. In the timing chart, the first potential difference VD of the power storage unit 11 is approximately flat from time T2 to time T3, which corresponds to the maintenance period, but in reality, voltage fluctuations of the vehicle battery 14 and power storage The first potential difference VD of power storage unit 11 may gradually decrease due to natural discharge of unit 11 or the like. For this reason, the control unit 13 controls the second potential difference VI of the variable voltage unit 12 periodically or at the time when it is detected that the first potential difference VD of the power storage unit 11 is lower than the threshold value, and controls the second potential difference VI of the variable voltage unit 12 so that the first potential difference VD The value obtained by adding the second potential difference VI to the set voltage VD2 is maintained at a constant value.

The above charging period and maintenance period are when the terminal voltage VB of the vehicle battery 14 is being supplied to the vehicle power system 7 as a normal value. In other words, the voltage of the input section 8 is higher than the input threshold value Vth and This is an operating period provided when the battery 14 is healthy. The operation related to charging the power storage unit 11 during the charging period is performed during the entire period after the vehicle 18 is started, during which the voltage of the input unit 8 is higher than the input threshold value Vth, or when the voltage of the input unit 8 is higher than the input threshold value Vth. This may be done as necessary during a portion of the high-performance period.

In the above description, although the charging period and the maintenance period are controlled as different periods, the charging period and the maintenance period may be combined as a charging period. In addition, although the explanation is given in the form that power is supplied from the vehicle battery 14 to the vehicle power supply system 7 during the charging period or the maintenance period, a weak power supply from the vehicle battery 14 occurs while the vehicle 18 is starting or stopping. The current may charge the power storage unit 11 to the basic voltage VD1 or start the control unit 13. At this time, the above-mentioned weak current is supplied by an auxiliary switch (not shown) provided separately from the interlocking switch 19 and connected to the vehicle battery 14 and the input section 8, or by an auxiliary switch (not shown) provided separately from the input section 8. This may also be done by a separate power supply path (not shown).

Next, the discharge period will be explained. At time T3 when the discharging period begins, the first potential difference VD of power storage unit 11 is approximately charged to the set voltage VD2 due to the charging period and the sustaining period. Then, until time T3 when the discharge period begins, the vehicle battery 14 has the terminal voltage VB, and the output unit 9 receives the set voltage VD2 from the vehicle power supply system 7 and the terminal voltage VB from the vehicle battery 14. Both are supplied. At this time, the terminal voltage VB is the set voltage VD2
Since the voltage is set at a higher voltage value than T3, the vehicle battery 14 basically supplies power to the vehicle load 15 before time T3.

Here, when the terminal voltage of the vehicle battery 14 suddenly decreases at time T3 when the external signal receiving section 17 is receiving the vehicle starting signal SIG1, in other words, the interlocking switch 19 changes the connection state while the vehicle 18 is starting. When the control unit 13 detects that the terminal voltage of the vehicle battery 14 suddenly decreases and becomes lower than the input threshold value Vth at the time T3 despite the continuation, the discharging period begins. This is a state in which the terminal voltage of the vehicle battery 14 is rapidly decreasing even though the passenger of the vehicle 18 has not performed any operation to stop the vehicle 18 from starting, and the vehicle 18 is in an accident. This corresponds to the case where the battery has failed. The timing chart shows a curve in which the vehicle activation signal SIG1 continues even after time T3; (not shown).

As described above, until time T3, both the set voltage VD2 from the on-vehicle power supply system 7 and the terminal voltage VB from the vehicle battery 14 are supplied to the output unit 9, and the power to the vehicle load 15 is The supply was basically performed by the vehicle battery 14. However, since the vehicle battery 14 has lost power, the vehicle battery 14 has lost power, or is in a similar battery failure state, power cannot be supplied to the vehicle load 15. The in-vehicle power supply system 7 performs this.

When the battery fails, power for driving the control unit 13 is supplied from the power storage unit 11. Further, before the time T3 before the battery failure state occurs, electric power for driving the control unit 13 is supplied from either the vehicle battery 14, the power storage unit 11, or both. Moreover, the electric power for driving the control unit 13 is a very small value compared to the electric power output to the vehicle load 15. Therefore, the control unit 13 can operate for a sufficiently long period using the power from the power storage unit 11.

As shown in the timing chart, in the discharging period after time T3, when the power storage unit 11 of the vehicle-mounted power supply system 7 starts supplying power from the output unit 9 to the vehicle load 15, the first potential difference VD of the power storage unit 11 simultaneously increases. begins to decline. The control section 13 detects the first potential difference VD, and further operates the variable voltage section 12. Variable voltage section 12 corresponds to a bias voltage applied to first potential difference VD of power storage section 11 . The variable voltage section 12 begins to output the second potential difference VI, which was zero until time T3, and at the same time, the second potential difference VI begins to rise. The second potential difference VI compensates for the decrease in the first potential difference VD, and the output voltage of the output section 9 is maintained at a constant value. In other words, the control unit 13 determines the constant set voltage VD2 by adding the second potential difference VI, which is the voltage of the variable voltage unit 12, to the potential difference between the high potential electrode 11A and the low potential electrode 11B, which corresponds to the first potential difference VD. The variable voltage section 12 is controlled so as to output it as a value. Thereby, the control unit 13 can control the discharge state of the power storage unit 11 by controlling the second potential difference VI of the variable voltage unit 12.

As described above, control unit 13 can control the charging state of power storage unit 11 by controlling second potential difference VI of variable voltage unit 12 during the charging period. Then, during the discharge period, control unit 13 can control the discharge state of power storage unit 11 by controlling second potential difference VI of variable voltage unit 12. In other words, the variable voltage section 12 performs the charging operation and the discharging operation with a single circuit, and the on-vehicle power supply system 7 can be downsized.

Here, as described above, since the upper limit of the set voltage VD2 is the terminal voltage VB of the vehicle battery 14, the second potential difference VI is always a value lower than the terminal voltage VB of the vehicle battery 14. Therefore, the variable voltage section 12 that generates the second potential difference VI is operated as a step-down converter using the voltage of the output section 9, and especially during the discharging period, the second potential difference VI is the voltage of the power storage section 11, which is the first potential difference VD. It is preferable to control the value to be smaller than . Buck converters have high power conversion efficiency. In the above operation, since the variable voltage section 12 is provided to cause a change in voltage, the power consumption in the variable voltage section 12 is very small, and the power output from the output section 9 is limited to the power storage section 11. The electricity will be responsible for this. Therefore, even if the variable voltage section 12 is a step-down converter that operates using the voltage of the output section 9, the effect of the operation of the variable voltage section 12 on the output section 9 and the vehicle load 15 is very small. It can be suppressed. As a result, the variable voltage unit 12 can perform the functions of charging the power storage unit 11 and discharging the power storage unit 11 in a single circuit, thereby making it possible to downsize the on-vehicle power supply system 7 and improve the operation. Power saving can be achieved.

Particularly during the discharge period, the voltage of the variable voltage unit 12 is superimposed on the voltage of the power storage unit 11, and the voltage of the variable voltage unit 12 is supplemented by a gradual increase in the voltage of the variable voltage unit 12 to compensate for the gradual decrease in the voltage of the power storage unit 11. As a result of the control by the control unit 13, the voltage of the high potential electrode 11A of the power storage unit 11 is maintained at a value higher than the first potential difference VD of the power storage unit 11 and at a constant value to the extent possible. As a result, most of the power stored in the power storage unit 11 can be discharged and output, so that the power stored in the power storage unit 11 can be used efficiently.

The in-vehicle power supply system 7 operates even in situations where there is little power remaining in the power storage unit 11 and the voltage of the power storage unit 11 is decreasing, or when there is a large amount of power remaining in the power storage unit 11 and the voltage of the power storage unit 11 is close to full charge. Even under such circumstances, when discharging power from power storage unit 11, the operation in which the voltage of power storage unit 11 is boosted by a boost converter provided between power storage unit 11 and output unit 9 does not necessarily have to be used. . Therefore, the first potential difference VD, which is the voltage of the power storage unit 11, does not need to be higher than a voltage value that can be boosted.

Generally, when boosting a voltage using a boost operation, the voltage before being boosted needs to be higher than the lower limit of the voltage before boosting, which is an inherent value of the circuit for the boost operation. Therefore, when boosting the voltage using a boost operation, the power of the storage element corresponding to a voltage lower than the lower limit of the voltage before boosting becomes wasted power that cannot be used as output power.

In the vehicle-mounted power supply system 7 of the present disclosure, the first potential difference VD, which is the voltage of the power storage unit 11, does not need to be higher than a voltage value that can be boosted. Therefore, even in a situation where there is little power remaining in the power storage unit 11 and the voltage of the power storage unit 11 is decreasing, it is possible to continue discharging power from the power storage unit 11, compared to a power supply using boost operation. The on-vehicle power supply system 7 can efficiently utilize the power stored in the power storage unit 11. In other words, the on-vehicle power supply system 7 can output a large amount of power over a long period of time.

Furthermore, as explained in the discharging period, when the vehicle battery 14 loses power or is in a similar state, the vehicle power supply system 7 supplies power to the vehicle load 15. 7 does. Therefore, the electric power possessed by power storage unit 11 may be completely used up during the discharge period. Therefore, at the time TX when the power storage unit 11 has almost no remaining power, it is no longer possible to supply a predetermined voltage to the output unit 9, and the variable voltage unit 12 using a step-down converter also stops operating, the on-vehicle power supply system 7 is activated. Stop functioning.

Further, the timing chart during the discharge period shows, as an example, a case where vehicle load 15 continuously consumes power from power storage unit 11 over time, and first potential difference VD of power storage unit 11 gradually decreases. However, vehicle load 15 may consume power discontinuously, and first potential difference VD of power storage unit 11 may decrease stepwise. In that case, the second potential difference VI of the variable voltage section 12 rises in a stepwise manner, and then the control section 13 controls the variable voltage section 12 to change the potential difference between the high potential electrode 11A and the low potential electrode 11B corresponding to the first potential difference VD. The variable voltage unit 12 is controlled so that the value obtained by adding the second potential difference VI, which is the voltage of the set voltage VD2, is outputted as a constant value of the set voltage VD2.

If the vehicle load 15 is an actuator that needs to operate when the vehicle 18 is in an emergency situation, the vehicle load 15 discontinuously consumes power due to discontinuous operation. However, the control unit 13 sets the value obtained by adding the second potential difference VI, which is the voltage of the variable voltage unit 12, to the potential difference between the high potential electrode 11A and the low potential electrode 11B, which corresponds to the first potential difference VD, to the constant value of the set voltage VD2. By controlling the variable voltage section 12 so as to output power as follows, the vehicle-mounted power supply system 7 can output a large amount of power over a long period of time, similarly to when the vehicle load 15 operates continuously.

In the description of the discharge period, the case where the discharge period becomes lower than the input threshold value Vth while the external signal receiving unit 17 is receiving the vehicle activation signal SIG1 has been described. Here, if the external signal receiving section 17 goes from receiving the vehicle starting signal SIG1 to no longer receiving it, and at the same time the voltage of the input section 8 becomes lower than the input threshold Vth, the control section 13 will control the vehicle 18 to be in the starting state. It may be determined that the state has changed from the state to the stopped state. This is a state in which the vehicle 18 is stopped in the normal order by the passenger, and at the same time as the interlocking switch 19 switches from the connected state to the cutoff state, the voltage of the input section 8 becomes lower than the input threshold Vth. In some cases, the control unit 13 may determine that the activation/stopping is normal.

At this time, as described above, both the set voltage VD2 from the on-vehicle power supply system 7 and the terminal voltage VB from the vehicle battery 14 are supplied to the output unit 9, but the terminal voltage VB is higher than the set voltage VD2. It is set at a high voltage value. Therefore, before time T3, the vehicle battery 14 basically supplies power to the vehicle load 15. Then, the control unit 13 controls the power storage unit 11 so as to lower the first potential difference VD of the power storage unit 11 to the base voltage VD1.

The discharge period described above operates based on the vehicle activation signal SIG1 and the voltage at the input section 8, but the second operation timing of the on-vehicle power supply system 7 in the embodiment of the present invention shown in FIG. As shown in the chart, the discharge period may be started when the external signal receiver 17 receives the emergency activation signal SIG2. The emergency activation signal SIG2 in this case is a signal transmitted from a control unit (not shown) mounted on the vehicle body 22 or the like when the vehicle 18 encounters an accident.

Furthermore, if the discharge period is started when the external signal receiving section 17 receives the emergency activation signal SIG2, the control section 13 may detect the vehicle activation signal SIG1 and the voltage at the input section 8 at the same time as the emergency activation signal SIG2. However, the control unit 13 does not need to use the vehicle activation signal SIG1 or the voltage at the input unit 8 to determine whether to perform an operation related to the discharge period.

As with the case where the operation regarding the discharge period is based on the vehicle activation signal SIG1 or the voltage at the input section 8, the control section 13 varies the potential difference between the high potential electrode 11A and the low potential electrode 11B corresponding to the first potential difference VD. The variable voltage section 12 is controlled so that the value obtained by adding the second potential difference VI, which is the voltage of the voltage section 12, is outputted as a constant value of the set voltage VD2. This makes it possible to continue discharging power from the power storage unit 11 even under a situation where there is little remaining power in the power storage unit 11 and the voltage of the power storage unit 11 has decreased, and the on-vehicle power supply system 7 The stored power can be used efficiently. In other words, the on-vehicle power supply system 7 can output a large amount of power over a long period of time.

Here, more precisely, as shown in the fourth circuit block diagram showing the configuration of the on-vehicle power supply system in the embodiment of the present invention in FIG. An adder circuit 32 connected to G may be provided. The adder circuit 32 is composed of a circuit having, for example, a resistor or impedance that enables voltage maintenance. In other words, a voltage maintenance circuit (not shown) is connected between the connection point between the low potential electrode 11B and the high potential electrode 12A and the ground G.

Addition circuit 32 is controlled to connect a path from power storage unit 11 to ground via a voltage maintenance circuit (not shown) while maintaining the voltage generated by variable voltage unit 12 during charging. During discharging, control is performed to cut off the path from power storage unit 11 to ground via a voltage maintenance circuit (not shown). Thereby, the voltages of power storage unit 11 and variable voltage unit 12 can be added to accurately obtain the voltage of output unit 9. Furthermore, although the variable voltage section 12 and the addition circuit 32 are described and explained as separate elements in FIG. 6, the functions and operations of the addition circuit 32 may be included in the variable voltage section 12.

Up to this point, the case where a step-down converter is used in the variable voltage section 12 has been described as an example. When a step-down converter is used for the variable voltage section 12, the control section 13 maintains a constant setting voltage VD2 obtained by adding the potential difference VD of the power storage section 11 and the potential difference VI of the variable voltage section 12, as described above. The variable voltage unit 12 is controlled so that Further, the maximum value of potential difference VI that can be generated by variable voltage section 12 is limited to correspond to potential difference VD of power storage section 11.

Therefore, at the time TX0 when the potential difference VD of power storage unit 11 becomes less than half of set voltage VD2, potential difference VI generated by variable voltage unit 12 also becomes less than half of set voltage VD2. As a result, the set voltage VD2 is no longer able to maintain a predetermined constant value set in advance, and the value gradually decreases after the time TX0. Then, at the time TX when the residual voltage of the power storage unit 11 and the voltage generated by the variable voltage unit 12 both decrease and it becomes impossible to drive the vehicle load 15, the actual function of the on-board power supply system stops. do.

Therefore, as an example, as shown in the fifth circuit block diagram illustrating the configuration of the on-vehicle power supply system in the embodiment of the present invention in FIG. Any of these may be configured by a circuit or a converter capable of doing so. In this case, the variable voltage section 12 includes a switching element 24 , a driver 30 that drives the switching element 24 , a smoothing capacitor 27 , a rectifying element 28 , and a transformer 31 . A cathode of a rectifying element 28 and one end of a smoothing capacitor 27 are connected to the low potential electrode 11B of the power storage unit 11. Further, the anode of the rectifier 28 is connected to one end of the first winding 31A of the transformer 31, and the other end of the first winding 31A and the other end of the smoothing capacitor 27 are connected, respectively. The other end of the first winding 31A and the other end of the smoothing capacitor 27 may be connected to ground G, a reference voltage different from ground G (for example, 0V), or may be connected to ground G or the reference voltage. It may be in a floating state without being connected to. Further, the second winding 31B of the transformer 31 and the switching element 24 are connected in series between the output section 9 and the ground G.

Here, switching of the switching element 24 is controlled by a signal (such as a PWM signal) issued from the driver 30, and the control section 13 generates an arbitrary voltage across the second winding 31B. Then, a voltage is generated across the first winding 31A corresponding to the voltage generated across the second winding 31B. The voltage generated across the first winding 31A is rectified by the rectifying element 28, and the rectified voltage is further smoothed by the smoothing capacitor 27, so that a DC voltage is created between the high potential electrode 12A and the low potential electrode 12B. generated.

Thereby, during the discharge period, the potential difference VI generated by the variable voltage section 12 can be controlled by the control section 13 so as to have a larger value than the potential difference VD of the power storage section 11. As a result, even if the potential difference VD of the power storage unit 11 is less than half of the set voltage VD2, the potential difference VI of the variable voltage unit 12 can be more than half the set voltage VD2. In other words, the potential difference VI of variable voltage section 12 can be larger than the potential difference VD of power storage section 11. Therefore, the potential difference VI of variable voltage section 12 is
The set voltage VD2 can be maintained at a constant value by adding it to the potential difference VD.

Therefore, even in a situation where there is little power remaining in the power storage unit 11 and the voltage of the power storage unit 11 is decreasing, it is possible to continue discharging power from the power storage unit 11, and the on-vehicle power supply system 7 can continue to discharge power from the power storage unit 11. The generated power can be used efficiently. In other words, the on-vehicle power supply system 7 can output a large amount of power over a long period of time.

In addition, during the charging period, as described above, the power storage unit 11 is charged by changing the second potential difference VI of the variable voltage unit 12 according to the charging current that the control unit 13 sends to the power storage unit 11. Alternatively, the second potential difference VI of the variable voltage section 12 may be fixed at zero, and the power storage section 11 may be charged by the terminal voltage VB of the vehicle battery 14 itself. By controlling the second potential difference VI of variable voltage unit 12 by control unit 13 to adjust the current flowing to power storage unit 11, variable voltage unit 12 can respond to the time required for charging power storage unit 11 and overcurrent.

As another example, as shown in the sixth circuit block diagram of FIG. 8 showing the configuration of the on-vehicle power supply system according to the embodiment of the present invention, the variable voltage section 12 has a power storage The unit 11 may be configured by a circuit or a converter capable of both raising and lowering the voltage. Here, the variable voltage section 12 also includes a switching element 24 , a driver 30 that drives the switching element 24 , a smoothing capacitor 27 , a rectifying element 28 , and a transformer 31 . A cathode of a rectifying element 28 and one end of a smoothing capacitor 27 are connected to the low potential electrode 11B of the power storage unit 11. Further, the anode of the rectifier 28 is connected to one end of the first winding 31A of the transformer 31, and the other end of the first winding 31A and the other end of the smoothing capacitor 27 are connected, respectively. The other end of the first winding 31A and the other end of the smoothing capacitor 27 may be connected to ground G, a reference voltage different from ground G (for example, 0V), or may be connected to ground G or the reference voltage. It may be in a floating state without being connected to. Further, the second winding 31B of the transformer 31 and the switching element 24 are connected in series between the output section 9 and the low potential electrode 11B of the power storage section 11.

Here, switching of the switching element 24 is controlled by a signal (such as a PWM signal) issued from the driver 30, and the control section 13 generates an arbitrary voltage across the second winding 31B. Then, a voltage is generated across the first winding 31A corresponding to the voltage generated across the second winding 31B. The voltage generated across the first winding 31A is rectified by the rectifying element 28, and the rectified voltage is further smoothed by the smoothing capacitor 27, so that a DC voltage is created between the high potential electrode 12A and the low potential electrode 12B. generated.

As a result, during the discharge period, the voltage remaining in power storage unit 11 is directly used, and the potential difference VI generated in variable voltage unit 12 is controlled to be a larger value than the potential difference VD of power storage unit 11. It becomes possible to be controlled by the unit 13. As a result, even if the potential difference VD of the power storage unit 11 is less than half of the set voltage VD2, the potential difference VI of the variable voltage unit 12 can be more than half the set voltage VD2. Therefore, by adding the potential difference VI of variable voltage section 12 to the potential difference VD of power storage section 11, set voltage VD2 can be maintained at a constant value.

Although a step-up operation using the low voltage remaining in the power storage unit 11 is required here, the variable voltage unit 12 that performs the step-up operation on the voltage of the power storage unit 11 does not supply power to the vehicle load 15; A DC voltage is supplied between the high potential electrode 12A and the low potential electrode 12B of the section 12. The power supply at this time is a very small value. Therefore, the step-up operation in variable voltage section 12 is possible even when the voltage remaining in power storage section 11 is low.

Although not shown in FIGS. 7 and 8, an adder circuit 32 may be provided between the low potential electrode 11B and the high potential electrode 12A, similarly to FIG. 6. As described above, the addition circuit 32 maintains the voltage generated by the variable voltage section 12 during charging and connects the path from the power storage section 11 to the ground via the voltage maintenance section (not shown). During discharging, control is performed to cut off the path from power storage unit 11 to ground via a voltage maintenance circuit (not shown). Thereby, the voltages of power storage unit 11 and variable voltage unit 12 can be added to accurately obtain the voltage of output unit 9.

Here, the external signal receiving section 17 does not need to have a configuration with a specific function, and may be a terminal that can be electrically connected using a fixture or welding, or a conductor that can be connected by welding or the like. It may be. In addition, in order to prevent backflow of power from the power storage unit 11 to the input unit 8 side during the discharge period, a rectifying element 23 whose anode is connected to the input unit 8 and whose cathode is connected to the connection point 16 is arranged. is desirable.

The elements constituting the on-vehicle power supply system 7 described above do not necessarily need to be housed and arranged within a single housing. In other words, the components (or functions) of the on-vehicle power supply system 7 may be distributed and provided in a plurality of housings. For example, power storage unit 11 may be provided in the same casing as that in which control unit 13 and the like are provided, or may be provided in a separate casing. Naturally, all the elements constituting the on-vehicle power supply system 7 may be housed and arranged in a single housing.

The in-vehicle power supply system of the present invention has the effect of being able to efficiently utilize the electric power stored in the power storage unit, and is useful in various vehicles.

7 Vehicle-mounted power supply system 8 Input section 9 Output section 10 Conductive line section 11 Power storage section 11A High potential electrode 11B Low potential electrode 12 Variable voltage section 12A High potential electrode 12B Low potential electrode 12P Power supply path 13 Control section 14 Vehicle battery 15 Vehicle load 16, 26, 29 connection point 17 external signal receiving section 18 vehicle 19 interlocking switch 20 normal route section 21, 23, 28 rectifying element 22 vehicle body 24 switching element 25 choke coil 27 smoothing capacitor 30 driver 31 transformer 31A 1st winding 31B 2nd winding 32 Adder circuit G Ground

Claims (11)

an input section;
an output section;
a conductive line connecting the input section and the output section;
a power storage unit having a high potential electrode and a low potential electrode, and the conductive line portion is connected to the high potential electrode;
a variable voltage section connected between the low potential electrode and ground;
a control unit connected to the power storage unit and the variable voltage unit to control the variable voltage unit,
The control unit is configured to set a value obtained by adding the voltage of the variable voltage unit to the potential difference between the high potential electrode and the low potential electrode to a predetermined constant value during a charging period and a discharging period of the power storage unit. Controls the voltage of the variable voltage section,
In-vehicle power system. The power storage unit uses a capacitor as a power storage element,
The on-vehicle power supply system according to claim 1. The variable voltage section is a converter that generates a potential difference using the voltage of the output section,
The potential difference of the variable voltage section during the discharge period is a smaller value than the potential difference of the power storage section.
The on-vehicle power supply system according to claim 1. The variable voltage section is a converter that generates a potential difference using the voltage of the output section,
The potential difference of the variable voltage section during the discharge period is larger than the potential difference of the power storage section,
The on-vehicle power supply system according to claim 1. The charging period is provided when the voltage of the input section is higher than an input threshold voltage,
The on-vehicle power supply system according to claim 1 . further comprising an external signal receiving section connected to the control section,
The discharge period is started when the voltage of the input section becomes lower than an input threshold voltage while the external signal receiving section is receiving a vehicle activation signal.
The on-vehicle power supply system according to claim 1. further comprising an external signal receiving section connected to the control section,
The discharge period starts when the external signal receiving unit receives an emergency activation signal.
The on-vehicle power supply system according to claim 1. an input section;
an output section;
a conductive line connecting the input section and the output section;
a power storage unit having a high potential electrode and a low potential electrode, and the conductive line portion is connected to the high potential electrode;
a variable voltage section connected between the low potential electrode and ground;
a control unit connected to the power storage unit and the variable voltage unit to control the variable voltage unit,
The control unit controls the variable voltage unit to set a value obtained by adding the voltage of the variable voltage unit to the potential difference between the high potential electrode and the low potential electrode to a predetermined constant value during a discharge period of the power storage unit. control the voltage of
The variable voltage section is a converter that generates a potential difference using the voltage of the output section,
The potential difference of the variable voltage section during the discharge period is a smaller value than the potential difference of the power storage section.
In-vehicle power system. an input section;
an output section;
a conductive line connecting the input section and the output section;
a power storage unit having a high potential electrode and a low potential electrode, and the conductive line portion is connected to the high potential electrode;
a variable voltage section connected between the low potential electrode and ground;
a control unit connected to the power storage unit and the variable voltage unit to control the variable voltage unit,
The control unit controls the variable voltage unit so that a value obtained by adding the voltage of the variable voltage unit to the potential difference between the high potential electrode and the low potential electrode becomes a predetermined constant value during a discharge period of the power storage unit. control the voltage of
The variable voltage section is a converter that generates a potential difference using the voltage of the output section,
The potential difference of the variable voltage section during the discharge period is larger than the potential difference of the power storage section,
In-vehicle power system. an input section;
an output section;
a conductive line connecting the input section and the output section;
a power storage unit having a high potential electrode and a low potential electrode, and the conductive line portion is connected to the high potential electrode;
a variable voltage section connected between the low potential electrode and ground;
a control unit connected to the power storage unit and the variable voltage unit to control the variable voltage unit,
The control unit controls the variable voltage unit so that a value obtained by adding the voltage of the variable voltage unit to the potential difference between the high potential electrode and the low potential electrode becomes a predetermined constant value during a discharge period of the power storage unit. control the voltage of
further comprising an external signal receiving section connected to the control section,
The discharge period is started when the voltage of the input section becomes lower than an input threshold voltage while the external signal receiving section is receiving a vehicle activation signal.
In-vehicle power system. an input section;
an output section;
a conductive line connecting the input section and the output section;
a power storage unit having a high potential electrode and a low potential electrode, and the conductive line portion is connected to the high potential electrode;
a variable voltage section connected between the low potential electrode and ground;
a control unit connected to the power storage unit and the variable voltage unit to control the variable voltage unit,
The control unit controls the variable voltage unit so that a value obtained by adding the voltage of the variable voltage unit to the potential difference between the high potential electrode and the low potential electrode becomes a predetermined constant value during a discharge period of the power storage unit. control the voltage of
further comprising an external signal receiving section connected to the control section,
The discharge period starts when the external signal receiving unit receives an emergency activation signal.
In-vehicle power system.

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