JP2023165368A - Electrical power system - Google Patents

Abstract

To realize an electrical power system that can appropriately execute a vehicle stop operation without increasing the storage capacity of a backup power storage unit when the voltage of a primary power supply gradually decreases due to an abnormality.SOLUTION: An electrical power system includes a backup power supply 30 that supplies power to an on-vehicle load 40 when a voltage value Vp of a primary power supply 20 is smaller than a voltage value Vb of the backup power supply 30, an auxiliary charging circuit unit 50 that charges a power storage unit 34 from the primary power source 20, and a control unit 10 that controls charging and discharging of the primary power source 20 and the backup power source 30. When the backup power supply 30 does not supply power to the on-vehicle load 40, the control unit 10 causes the primary power supply 20 to charge the power storage unit 34, when the voltage value Vp of the primary power supply 20 is smaller than the voltage value Vb of the backup power supply 30 and is greater than or equal to a power failure determination voltage value Vl, the charging rate from the primary power source 20 to the power storage unit 34 is temporarily increased in preparation for a vehicle stop operation.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power supply system that supplies power to an on-vehicle load.

BACKGROUND ART Power supply systems that include a primary power source and a backup power source that supply power to various on-vehicle devices (on-vehicle loads) have been proposed. In such a power supply system, when the primary power supply fails, the backup power supply supplies power to the on-vehicle load. For example, a braking device disclosed in Patent Document 1 is a system that can promptly switch from the primary power source to a backup power source after detecting a failure of the primary power source and continuously supply power to an on-vehicle load. In Patent Document 1, a primary power source (first power system) and a backup power source (second power system) are connected in parallel. In normal times, the voltage of the primary power source is higher than the voltage of the backup power source, so power is supplied from the primary power source to the on-vehicle load. On the other hand, if the primary power supply fails and the voltage of the primary power supply becomes lower than the voltage of the backup power supply, the backup power supply automatically supplies power to the on-vehicle load. Here, the voltage of the backup power supply is set higher than the reference voltage used to determine that the primary power supply has failed, that is, the failure detection voltage. As a result, the braking device of Patent Document 1 can quickly supply power from the backup power source to the on-vehicle load when the primary power source fails.

Further, when the primary power supply fails, the on-vehicle load performs an operation to appropriately stop the vehicle (hereinafter referred to as "vehicle stopping operation"). Therefore, the backup power supply needs to secure sufficient power in the power storage unit for the on-vehicle load to perform a vehicle stop operation.

JP 2021-14173 Publication

In the conventional power supply system as disclosed in Patent Document 1, the voltage of the primary power supply is higher than the voltage of the backup power supply during normal times, and power is supplied from the primary power supply to the on-vehicle load. On the other hand, when the voltage of the primary power source decreases and the magnitude relationship between the voltage values of the primary power source and the backup power source is reversed, power is supplied from the backup power source to the on-vehicle load. That is, when the voltage of the primary power source becomes lower than the voltage of the backup power source, power is supplied from the backup power source to the on-vehicle load. During the period from when the voltage of the primary power source becomes less than the voltage of the backup power source until it is determined that the primary power source has failed, the backup power source supplies power to the on-vehicle load. Capacity gradually decreases. As a result, when it comes to actually stopping the vehicle using the power supplied to the on-vehicle load from the backup power source, the problem arises that the backup power source does not have the necessary capacity to stop the vehicle. There was a risk that this would occur.

In order to avoid the above problems, it is conceivable to increase the storage capacity of the storage unit (capacitor) of the backup power source. However, increasing the power storage capacity compared to the conventional power storage unit leads to an increase in the amount of natural discharge. Since the primary power source constantly charges the backup power source to compensate for the natural discharge of the backup power source, increasing the storage capacity of the backup power source increases the amount of power supplied from the primary power source to the storage unit of the backup power source. As a result, the power consumption of the primary power source increases, and the amount of heat generated in the entire power supply system increases. Furthermore, a power storage unit with a large power storage capacity is correspondingly large in size and expensive, leading to problems such as an increase in the size and cost of the power supply system.

Therefore, in this specification, even if some abnormality occurs in the primary power source and the voltage of the primary power source gradually decreases, the present invention provides a power source that can appropriately perform vehicle stopping operations without increasing the storage capacity of the power storage unit of the backup power source. Disclose the system.

The power supply system disclosed in this specification includes a primary power source that supplies power to an on-vehicle load and a power storage unit, and supplies power to the on-vehicle load when a voltage value of the primary power source is smaller than a voltage value of a backup power source. A power supply system comprising: a backup power supply to supply; an auxiliary charging circuit unit that charges the power storage unit from the primary power supply; and a control unit that controls power supply of the primary power supply and the backup power supply, wherein the control unit The unit causes the on-vehicle load to be continuously supplied with power from at least one of the primary power source and the backup power source, and when the backup power source is on standby without power being supplied from the backup power source to the on-vehicle load. , the control unit causes the power storage unit to be charged from the primary power source until the charging capacity of the power storage unit reaches full charge, and the control unit is configured to charge the power storage unit from the primary power source until the charging capacity of the power storage unit reaches full charge, and the voltage value of the primary power source is smaller than the voltage value of the backup power source, and the control unit When the voltage value of the power source is equal to or higher than the power failure determination voltage value, the control unit causes the primary power source to charge the power storage unit at a charging rate higher than the charging rate when the backup power source is on standby; It is characterized by allowing the backup power supply to replenish power.

According to the power supply system disclosed in this specification, even if some abnormality occurs in the primary power supply and the voltage of the primary power supply gradually decreases, the vehicle stopping operation can be performed without increasing the storage capacity of the power storage unit of the backup power supply. Can be executed properly.

FIG. 1 is a diagram showing the overall configuration of a power supply system. It is a sequence diagram of a power supply system. It is a flowchart which shows the operation procedure of a control part.

The power supply system will be described below with reference to the drawings.

FIG. 1 is a diagram showing the overall configuration of an on-vehicle load 40 mounted on a vehicle and a power supply system 100 that supplies power to the on-vehicle load 40. The power supply system 100 includes a control unit 10, a primary power supply 20, a backup power supply 30, an auxiliary charging circuit unit 50, and first to fourth switches SW1 to SW4. Backup power supply 30 includes a DC/DC step-up/down section 32 and a power storage section 34 that is a capacitor.

The primary power source 20 is a main power source that supplies power to the on-vehicle load 40. At least two power supply systems are provided from the primary power source 20 to the on-vehicle load 40. One is a system via the first switch SW1, and the other is a system via the second switch SW2 and the third switch SW3. The power supply system via the first switch SW1 supplies power to an accessory system that is a part of the on-vehicle load 40. For example, when the first switch SW1 is in a closed state, power is supplied from the primary power source 20 to an accessory system that supplies electricity to an audio device or the like. The power supply system via the second switch SW2 and the third switch SW3 is part of the on-vehicle load 40. For example, it supplies power to the ECU, doors, brake system, etc.

Further, the primary power source 20 charges the power storage unit 34 of the backup power source 30 in order to compensate for the natural discharge of the backup power source 30. As shown in FIG. 1, the primary power source 20 and the auxiliary charging circuit section 50 are connected via the fourth switch SW4, and the auxiliary charging circuit section 50 and the power storage section 34 of the backup power source 30 are also connected. Charging of the power storage unit 34 from the primary power source 20 is achieved by supplying electric power via the auxiliary charging circuit unit 50 when the fourth switch SW4 is in the closed state. That is, charging is performed by the auxiliary charging circuit unit 50 serving as a charger converting the electric power from the primary power source 20 and applying it to the power storage unit 34.

The backup power source 30 is connected in parallel with the primary power source 20, and is an auxiliary power source that supplies power to the on-vehicle load 40 instead when power is not normally supplied from the primary power source 20 to the on-vehicle load 40. To supply power from the backup power source 30 to the on-vehicle load 40, the control unit 10, which will be described later, transforms the output voltage of the power storage unit 34 to a predetermined voltage using a DC/DC step-up/down unit 32 directly connected to the power storage unit 34. This is achieved by closing the third switch SW3. As described above, the backup power supply 30 supplies power to the on-vehicle load 40 through the power supply system via the third switch SW3. That is, the backup power supply 30 serves as a substitute for the primary power supply 20 in an emergency and supplies power to the on-vehicle load 40. Hereinafter, in this example, the on-vehicle load 40 refers to on-vehicle devices such as an ECU, a door, and a brake system. In normal times, the voltage of the primary power supply 20 is higher than the output voltage from the DCDC buck-boost unit 32 (hereinafter referred to as "voltage of the backup power supply 30"), so power is supplied from the primary power supply 20 to the on-vehicle load 40. . On the other hand, when an abnormality occurs in the primary power source 20 and the voltage of the primary power source 20 decreases, the magnitude relationship between the voltage values of the primary power source 20 and the backup power source 30 is reversed. After the magnitude relationship between these two voltage values is reversed, power is supplied from the backup power supply 30 to the on-vehicle load 40.

The control unit 10 includes a microcomputer having a CPU, memory, and the like. The control unit 10 performs switching control to open and close the first to fourth switches SW1 to SW4. Further, the control unit 10 controls power supply from the power supply system 100 to the on-vehicle load 40. Specifically, the control unit 10 performs the following control. In order to compensate for power consumption due to natural discharge of the backup power source 30 itself, charging of the power storage unit 34 of the backup power source 30 from the primary power source 20 is controlled. Further, when the primary power source 20 fails, the vehicle is stopped. In this example, the "vehicle stopping operation" refers to an operation that avoids ECU reset and appropriately stops the vehicle. Furthermore, after the voltage of the primary power source 20 is equal to or higher than the power failure determination value and the voltage of the primary power source 20 becomes lower than the voltage of the backup power source 30, the power supply from the primary power source 20 to the backup power source 30 per unit time is performed for a predetermined period. Increase the amount of charge (hereinafter referred to as the "charging rate"). Furthermore, after the predetermined period has elapsed, the user is notified of the failure. Note that the operations of these control sections 10 will be described in detail later with reference to FIGS. 2 and 3.

Next, the operation of the power supply system 100 when some abnormality occurs and the voltage of the primary power supply 20 gradually decreases will be described using the sequence diagram of FIG. 2.

A solid line Vp in the first graph in FIG. 2 indicates the voltage value of the primary power source 20. In this example, the voltage of the primary power supply 20 during normal operation is Vmax, the voltage of the backup power supply 30 is Vb, and the power failure determination voltage is Vl. The magnitude relationship between the voltage Vp=Vmax of the primary power supply 20 and the voltage Vb of the backup power supply 30 during normal times (period up to t0 in the figure) is such that Vp=Vmax>Vb. Moreover, since the power supply failure determination voltage Vl is smaller than the voltage Vp of the primary power supply 20 and the voltage Vb of the backup power supply 30, the relationship in magnitude holds true: Vp=Vmax>Vb>Vl. A solid line Qb in the second graph indicates the remaining capacity of the backup power supply 30 of the power supply system 100 disclosed in this specification, that is, the amount of power remaining in the backup power supply 30. On the other hand, a two-dot chain line Qb' indicates the remaining capacity of the backup power supply of the conventional power supply system. In order to compensate for the natural discharge of the backup power source 30, power is constantly supplied from the primary power source 20 to the power storage unit 34 of the backup power source 30. Further, when the voltage Vp of the primary power source 20 is higher than the voltage Vb of the backup power source 30, no power is supplied from the backup power source 30 to the on-vehicle load 40. Therefore, Qb maintains the value of Qmax, which is the full charge capacity, during the period up to t1 in the figure. A solid line Wb in the third graph indicates the charging rate from the primary power source 20 to the backup power source 30 of the power source system 100 disclosed in this specification. On the other hand, a two-dot chain line Wb' indicates a charging rate from a primary power source to a backup power source in a conventional power source system. Further, the graphs in the lower two rows of FIG. 2 show the processing timing for notifying the user and the vehicle stop processing timing, respectively.

As shown in FIG. 2, during normal times (period up to t0), the voltage Vp of the primary power source 20, the remaining capacity Qb of the backup power source 30, and the charging rate Wb from the primary power source 20 to the backup power source 30 are constant. Further, the control unit 10 neither notifies the user nor stops the vehicle.

Next, consider a case where an abnormality occurs in the primary power source 20 (at time t0) and the voltage Vp of the primary power source 20 gradually decreases. During the period from t0 to t1, the voltage Vp of the primary power supply 20 is higher than the voltage Vb of the backup power supply 30 (Vp≧Vb), so the primary power supply 20 supplies power to the on-vehicle load 40, and the power is not supplied from the backup power supply 30. Not consumed. Furthermore, since the charging rates Wb and Wb' remain constant at the value of W1, the remaining capacities Qb and Qb' of the backup power supply 30 do not change and remain constant at the value of Qmax.

When the voltage Vp of the primary power supply 20 gradually decreases and the magnitude relationship of the voltage value with the voltage Vb of the backup power supply 30 is reversed, that is, when Vp becomes less than Vb (Vp<Vb) (after time t1), The backup power supply 30 takes over power supply to the on-vehicle load 40. On the other hand, since charging from the primary power source 20 to the backup power source 30 continues, the value of the voltage Vp of the primary power source 20 continues to decrease as shown in the graph. After this t1, the remaining capacity Qb' of the backup power supply of the conventional power supply system starts to decrease. This is because, while power consumption increases by supplying power to the on-vehicle load 40, the charging rate Wb' remains constant at W1. On the other hand, in the power supply system 100 disclosed in this specification, the control unit 10 increases the capacity of the auxiliary charging circuit unit 50. Here, increasing the capacity of the auxiliary charging circuit unit 50 refers to increasing the charging rate Wb from the primary power source 20 to the backup power source 30 compared to the normal charging rate. Specifically, the charging rate Wb from the primary power source 20 to the power storage unit 34 is significantly increased from W1 to W2 for a predetermined period (period from t1 to t2). Therefore, during the predetermined period (period from t1 to t2), the remaining capacity Qb of the backup power supply 30 does not decrease regardless of the power supply to the on-vehicle load 40, and remains constant at Qmax.

As shown in the second graph from the bottom of FIG. 2, immediately after a predetermined period of time (t2), the control unit 10 notifies the user of the occurrence of an abnormality in the primary power source 20. For example, the control unit 10 controls the on-vehicle load 40, turns on a failure warning light, and notifies the user. By notifying the user immediately after t2, the user himself/herself who learns of the failure of the primary power source 20 can appropriately stop the vehicle while the backup power source 30 is in a fully charged state.

If the vehicle system is stopped by the above-described vehicle stop operation by the user himself/herself, the processing of the control unit 10 ends, but here, the processing in the case where the vehicle stop operation by the user himself/herself is not performed will be described. In this case, the primary voltage will continue to drop even after the abnormality notification. Then, when the voltage Vp of the primary power source 20 becomes smaller than the power failure determination voltage Vl (Vp<Vl), that is, when the backup power source 30 determines that the primary power source 20 has failed (t3), the control unit 10 executes a vehicle stop operation. As is clear from FIG. 2, the remaining capacity Qb of the backup power supply 30 of the power supply system 100 disclosed in this specification at the time (t3) when the vehicle stop process is performed is higher than the remaining capacity Qb' of the conventional power supply system. , becomes significantly larger. This is because, as described above, the charging rate Wb from the primary power source 20 to the power storage unit 34 is increased for a predetermined period (period from t1 to t2). That is, in addition to the amount of power originally required to stop the vehicle, the amount of power consumed by the backup power source 30 to the on-vehicle load 40 between t1 and t2 is stored in the power storage unit 34 of the backup power source 30. This is because it has been replenished. The fact that the remaining capacity Qb of the backup power source 30 is sufficiently large at this time point t3 means that the vehicle stopping operation can be appropriately executed without increasing the storage capacity of the power storage unit 34 of the backup power source 30.

Next, the operating procedure of the control unit 10 when an abnormality occurs in the primary power source 20 will be described using FIG. 3.

As described above, the relationship between the voltage Vp of the primary power source 20, the voltage Vb of the backup power source 30, and the power failure determination voltage Vl during normal operation is Vp=Vmax>Vb>Vl. If an abnormality occurs in the primary power supply 20, this magnitude relationship will change, and accordingly, the control unit 10 controls each part of the power supply system 100 so that the vehicle stopping operation is performed appropriately. The details will be explained below.

In normal times, power is supplied from the primary power supply 20 to the on-vehicle load 40, so power supply from the backup power supply 30 is in a standby state. On the other hand, since power is consumed due to natural discharge of the backup power source 30 itself, the control unit 10 controls charging of the power storage unit 34 of the backup power source 30 from the primary power source 20 (step S10). Note that the charging rate at this point is the natural discharge amount, that is, W1 in FIG. 2 . Subsequently, the control unit 10 determines whether the voltage Vp of the primary power source 20 has become smaller than the voltage Vb of the backup power source 30 (step S12). If the voltage Vp of the primary power source 20 is equal to or higher than the voltage Vp of the backup power source 30 (No in step S12), the count in step S16, which will be described later, is reset (step S13), and the process returns to step S12. That is, until the voltage Vp of the primary power source 20 becomes lower than the voltage Vp of the backup power source 30, the control unit 10 continues charging for the natural discharge amount. On the other hand, if the voltage Vp of the primary power source 20 is lower than the voltage Vb of the backup power source 30 (Yes in step S12), power supply from the backup power source 30 to the on-vehicle load 40 is started. The process then proceeds to step S14.

The control unit 10 determines whether the voltage Vp of the primary power source 20 is equal to or higher than the power failure determination voltage Vl (step S14). If the voltage Vp of the primary power source 20 is smaller than the power failure determination voltage Vl (No in step S14), the control unit 10 starts the vehicle stopping operation (step S24). On the other hand, if the voltage Vp of the primary power source 20 is equal to or higher than the power failure determination voltage Vl (Yes in step S14), the capacity of the auxiliary charging circuit unit 50 is increased for a predetermined period (10 seconds in this example). Step S16). At this time, the control unit 10 counts up (step S16). At this step S16 (after t1 in FIG. 2), the backup power supply 30 is already supplying power to the on-vehicle load 40. Furthermore, power is consumed due to the natural discharge of the backup power supply 30 itself. Therefore, it is necessary to set the charging rate to an amount that compensates for these power consumptions. After 10 seconds have passed (Yes in step S18), the control unit 10 finishes increasing the capacity of the auxiliary charging circuit unit 50 and notifies the user of the occurrence of an abnormality in the primary power source 20 (step S20). On the other hand, if the count value is less than 10 seconds (No in step S18), the process returns to step S12 and the processes from S12 to S18 are repeated. Therefore, if the voltage Vp of the primary power supply 20 recovers to the voltage Vb of the backup power supply 30 or higher before 10 seconds elapse (No in step S18, No in step S12), the count value is reset (step S13). . Furthermore, if the voltage Vp of the primary power source 20 becomes less than the power failure determination voltage Vl before 10 seconds elapse (No in step S18, Yes in step S12, No in step S14), the capacity of the auxiliary charging circuit section 50 The up-down is immediately ended, and the vehicle stopping operation is started (step S24).

After notifying the user of the occurrence of an abnormality in step S20, the control unit 10 again compares the voltage Vp of the primary power source 20 and the power failure determination voltage Vl. If the voltage Vp of the primary power source 20 is smaller than the power failure determination voltage Vl (Yes in step S22), the control unit 10 starts a vehicle stopping operation (step S24), and ends the series of processing. On the other hand, if the voltage Vp of the primary power source 20 is equal to or higher than the power failure determination voltage Vl (No in step S22), the process returns to step S22. That is, the control unit 10 waits without starting the vehicle stopping operation until the voltage Vp of the primary power source 20 becomes smaller than the power failure determination voltage Vl.

As described above, in the power supply system 100 disclosed in this specification, when the voltage Vp of the primary power supply 20 gradually decreases and becomes equal to or lower than the voltage Vb of the backup power supply 30, the power supply system 100 provides backup power from the primary power supply 20 for a predetermined period of time. Increase the charging rate Wb to the power source 30. As a result, it is possible to secure the electric power necessary for the vehicle stopping operation in the power storage unit 34 at the time when the power supply failure is determined, and the vehicle stopping operation can be appropriately executed.

The explanation so far is an example, and at least when the voltage value of the primary power source 20 is smaller than the voltage value of the backup power source 30 and is equal to or higher than the power failure determination voltage, the voltage from the primary power source 20 to the backup power source 30 is It is sufficient that the charging rate is higher than the normal charging rate. Other processes performed by the control unit 10 may be changed as appropriate. For example, in this example, the predetermined period is 10 seconds, but it is not limited to this, and the timing of notifying the user that an abnormality has occurred can be changed as appropriate.

Furthermore, in this example, after a predetermined period (period from t1 to t2 in FIG. 2) has elapsed, the remaining capacity Qb of the backup power supply 30 at time t2 is not reduced and remains at Qmax. However, in order to at least perform the capacity-up operation, the charging rate W2 during the predetermined period only needs to be higher than the charging rate W1 in normal times. Therefore, as long as W2>W1 is satisfied, the backup at time t2 after the predetermined period has elapsed. The remaining capacity Qb of the power supply 30 may be decreased from Qmax. Further, in this example, the capacity increasing operation is limited to a predetermined period, but the capacity increasing operation may continue until it is determined that the primary power source 20 has failed.

Reference Signs List 10 control unit, 20 primary power supply, 30 backup power supply, 32 DCDC buck-boost unit, 34 power storage unit, 40 onboard load, 50 auxiliary charging circuit unit, 100 power supply system.

Claims (1)

A primary power source that supplies power to an on-vehicle load;
a backup power supply having a power storage unit and supplying power to the on-vehicle load when the voltage value of the primary power supply is smaller than the voltage value of the backup power supply;
an auxiliary charging circuit unit that charges the power storage unit from the primary power source;
a control unit that controls power supply of the primary power source and the backup power source;
In a power supply system equipped with
The control unit causes the on-vehicle load to be continuously supplied with power from at least one of the primary power source and the backup power source,
When the backup power source is on standby without supplying power from the backup power source to the on-vehicle load, the control unit controls the supply of power from the primary power source to the power storage unit until the charging capacity of the power storage unit reaches full charge. charge it to
When the voltage value of the primary power source is smaller than the voltage value of the backup power source, and the voltage value of the primary power source is equal to or higher than a power failure determination voltage value, the control unit transmits the power from the primary power source to the power storage unit. replenishing power to the backup power source by charging at a higher charging rate than the charging rate when the backup power source is on standby;
A power supply system characterized by: