Power supply system

Abstract

To provide a power supply system capable of suppressing redundancy for achieving prescribed failure-time operation continuity and of utilizing indispensable redundancy to improve performance of a power distribution function such as load distribution on a current path.SOLUTION: A power supply system comprises a plurality of power sources for supplying power to a single load in a vehicle, a plurality of power supply paths for connecting between the single load and each of the plurality of power sources, and a current adjustment unit for adjusting current flowing through at least one power supply path among the plurality of power supply paths. The current adjustment unit compares state amounts of electrical states of the power supply paths, and when a difference between the state amounts meets prescribed conditions, adjusts current flowing through the power supply paths so as to reduce the difference between the state amounts.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a power supply system, and more particularly to an in-vehicle power supply system suitable for electric vehicles. [Background technology]

[0002] For some time now, the electrification of auxiliary components in automobiles, such as electric power steering and electric brakes, has been progressing. Furthermore, in recent years, the electrification of the main engine itself has also progressed, as exemplified by hybrid and electric vehicles. In addition, autonomous driving is advancing, and in the future, even in the event of a malfunction, it will be increasingly necessary for the operation of the vehicle to be completed autonomously and automatically without human intervention. Against this backdrop, there is a growing demand for high performance and high reliability (continuity of operation in the event of a malfunction) of on-board power supply systems that support the electrification and automation of automobiles.

[0003] Regarding the above technology, for example, Patent Document 1 discloses technology for redundancy of the power supply unit in addition to redundancy of the control unit, and also discloses technology for operating the control unit in power-saving mode in the event of a power supply unit failure. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2014-193720 [Overview of the project] [Problems that the invention aims to solve]

[0005] According to the conventional technology described above, making the power distribution function redundant to ensure continued operation in the event of a failure leads to increased costs; therefore, further consideration of cost reduction is desirable. Therefore, the present invention aims to reduce redundancy required to achieve a predetermined level of operational continuity in the event of a failure, while utilizing the essential redundancy to improve the performance of power distribution functions such as load balancing on the current path. [Means for solving the problem]

[0006] To achieve the above objective, the power supply system according to the present invention comprises a plurality of power sources that supply power to a single load in a vehicle, a plurality of power supply paths connecting the single load and each of the plurality of power sources, and a current adjustment unit that adjusts the current flowing through at least one of the plurality of power supply paths. The current adjustment unit compares the state quantities of the electrical states of each power supply path, and when the difference in the state quantities satisfies a predetermined condition, it adjusts the current flowing through the power supply path to reduce the difference in the state quantities. [Effects of the Invention]

[0007] By adopting the above configuration, the present invention reduces the redundancy required to achieve predetermined operational continuity in the event of a failure, while utilizing the essential redundancy to improve the performance of power distribution functions such as load balancing on the current path. Further features related to the present invention will become apparent from the description herein and the accompanying drawings. Problems, configurations, and effects other than those described above will be revealed by the following description of the embodiments. [Brief explanation of the drawing]

[0008] [Figure 1] A schematic diagram showing the basic configuration of the present invention. [Figure 2] This figure shows a configuration in which a control variable resistor is provided on the downstream side in the basic configuration of the present invention. [Figure 3] A diagram illustrating the control by switching in the basic configuration of the present invention. [Figure 4] This diagram illustrates control combined with switching in the basic configuration of the present invention. [Figure 5] A diagram illustrating the combination of voltage source output voltage control and switching control. [Figure 6] A block diagram showing the configuration of an electronic control unit according to one embodiment. [Figure 7] A block diagram showing the functional configuration of the control unit. [Figure 8]Figure showing the processing of the control unit based on the average current. [Figure 9] Figure showing the processing of the control unit based on the root mean square of the current. [Figure 10] Block diagram showing the configuration of the electronic control unit connected to the wire harness. [Figure 11] Figure showing the processing of the control unit based on the total current. [Figure 12] Figure showing the processing of the control unit based on the temperature rise. [Figure 13] Figure showing the configuration of the control unit having a fault response function. [Figure 14] Figure showing the processing of the control unit having a fault response function. [Figure 15] Block diagram showing the outline of the in-vehicle power supply network. [Figure 16] Figure showing an example of power supply to an important load. [Figure 17] Figure showing another example of power supply to an important load. [Figure 18] Figure showing an example of the configuration of a two-input switching regulator. [Figure 19] Figure showing another example of the configuration of a two-input switching regulator. [Figure 20] Figure showing another example of the configuration of a two-input switching regulator. [Figure 21] Figure showing another example of the configuration of a two-input switching regulator. [Figure 22] Figure showing an example of the configuration of the in-vehicle power supply network using a two-input switching regulator.

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0010] FIG. 1 is a diagram showing the basic configuration in an embodiment of the power supply system according to the present invention. The power supply system comprises multiple power sources that supply power to a single load RL, multiple current paths 20-1 and 20-2 connecting the load RL and the multiple power sources, and current adjusting means 10-1 and 10-2 provided in each of the multiple current paths 20-1 and 20-2 to adjust the current flowing through the current paths 20-1 and 20-2. The voltages of the multiple power sources are V1 and V2, respectively, and the wiring resistances of the current paths 20-1 and 20-2 are r1 and r2, respectively. In Figure 1, the current adjusting means 10-1 and 10-2 are located on the upstream side of the current paths 20-1 and 20-2, but they may also be located on the downstream side. Here, the upstream side of the current path refers to the region relatively close to the power source between the power source and the load, and the downstream side refers to the region close to the load.

[0011] Current adjustment means 10-1 and 10-2 can be, for example, control variable resistors made of semiconductor elements such as FETs (Field Effect Transistors). Figure 2 shows an example in which a control variable resistor rc1 is inserted in series downstream of the current path as the current adjustment means 10-1.

[0012] Figure 3 shows an example of adjusting the current flowing through a current path by switching. As shown in Figure 3(a), in this embodiment, a switching element SW1 is positioned upstream of the current path 20-1 as the current adjustment means 10-1. The switching element SW1 switches the current flowing through the current path 20-1 on and off, keeping the current flowing through the current path 20-2 always on. The waveform at this time is shown in Figure 3(b).

[0013] As shown in Figure 3(b), the current I1 flowing through current path 20-1 flows while SW1 is ON and is 0 during the time β1 when SW1 is OFF. On the other hand, the current I2 flowing through current path 20-2 increases during the time β1 when SW1 is OFF because all the current flows through current path 20-2, and decreases when SW1 is ON because current also flows through current path 20-1. With this configuration, if there are multiple current paths, current will always flow through some of the current paths. Therefore, even when the current in other current paths is interrupted, the current in the entire circuit will not suddenly drop to 0. In a normal switching regulator, when the flowing current suddenly drops to 0, flyback voltage and noise may be generated, potentially causing circuit failure, and freewheeling diodes and choke coils are required to suppress these, but these are unnecessary in this embodiment. Furthermore, by adjusting the current flowing through one current path, it is possible to prevent heat from concentrating in one current path and maintain a balance of heat generation between current paths. Note that this embodiment describes the case where there are two current paths, but the number of current paths is not limited to this.

[0014] Here, we determine the currents I1 and I2 flowing through current paths 20-1 and 20-2, given that the output voltages of the power sources are V1 and V2, the resistances of the current paths are r1 and r2, and the resistance of the load is RL. Focusing on the voltage at point A, according to Kirchhoff's laws, V1-r1 I1=V2 - r2 I2=(I1 + I2) RL...(1) Here, from equation (1), side 1 = side 2, I1 = (V1 - V2 + r2 I2) / r1 ... (2) Furthermore, since the second side of equation (1) equals the third side, substituting equation (2) into the third side, I2={(RL+r1) V2-RL V1} / {r1 r2+(r1+r2) RL}...(3) formula( 3 ) into formula ( 2 Substituting this into ) I1={(RL+r2) V1-RL V2} / {r1 r2+(r1+r2) RL}...(4) This is the result.

[0015] Next, we determine the average currents I1ave and I2ave flowing through current paths 20-1 and 20-2 when either current path 20-1 or current path 20-2 is turned off for times β1 and β2 (duty cycle 1-β1 or 1-β2), and the other current path is kept on (duty cycle 1).

[0016] First, as shown in Figure 3(b), when current path 20-1 is turned off by β1 (duty cycle is 1-β1) and current path 20-2 is kept on (duty cycle is 1), current I1 flows through current path 20-1 only when it is turned on. I1ave=(1-β1) I1···(5) This is the result.

[0017] On the other hand, when current path 20-1 is ON, I2 obtained from equation (3) flows through current path 20-2, and when current path 20-1 is OFF, I2' = V2 / (r2 + RL) ... (6) A current flows, and its average current is I2ave=(1-β1)I2+β1 I2'...(7) This is the result.

[0018] Similarly, when current path 20-2 is turned off by β2 (duty cycle 1-β2) and current path 20-1 is always on (duty cycle 1), current I2 flows through current path 20-2 only when it is on. I2ave = (1-β2)I2···(8) This is the result.

[0019] On the other hand, current path 20-1 has I1 obtained by equation (4) when current path 20-2 is ON, and when current path 20-2 is OFF, I1'=V1 / (r1+RL)···(9) A current flows, and the average current is I1ave=(1-β1)I1+β1 I1'...(10) This is the result.

[0020] Figure 4 shows a configuration in which current adjustment means are placed in both current paths 20-1 and 20-2, and the current flowing through current paths 20-1 and 20-2 is adjusted by pulse width modulation (PWM). In this embodiment, as shown on the left side of Figure 4(a), switching elements SW1 and SW2 are provided upstream of current paths 20-1 and 20-2 as current adjustment means 10-1 and 10-2 (see Figure 1). The current flowing through current paths 20-1 and 20-2 is adjusted by turning SW1 and SW2 on and off.

[0021] Specifically, switching elements SW1 and SW2 are switched on and off alternately, turning off current path 20-1 for a time β1 and current path 20-2 for a time β2. In this case, as shown in Figure 4(b), by overlapping the times when both are turned on (but not overlapping the duty cycles β1 and β2), current will always flow through one of the current paths. Therefore, even when the current in the other current path is interrupted, the current in the entire circuit will not abruptly drop to zero, eliminating the need for freewheeling diodes and choke coils that are required in conventional switching regulators. Furthermore, by adjusting the current flowing through one current path, it is possible to prevent heat from concentrating in one current path and maintain a balance of heat generation between the current paths. The times β1 and β2 for turning off the current paths can be set as appropriate.

[0022] More preferably, by making the switching by switching elements SW1 and SW2 soft switching with a limited rate of current change per unit time di / dt, surges and noise caused by the inductance of the current paths 20-1 and 20-2 can also be suppressed. Note that switching elements SW1 and SW2 can be semiconductor elements such as MOSFETs, and soft switching can be achieved by controlling the gate drive voltage to change gradually or by incorporating a time constant circuit using resistors and capacitors.

[0023] Furthermore, the current adjustment between current paths according to the present invention can balance the heat generation between current paths as described above, preventing heat generation from concentrating in one current path. To achieve this, the switching period of the PWM should be shorter than the thermal time constant of the current path. Specifically, a slow period of several hundred milliseconds to several seconds is sufficient. Therefore, the increase in switching losses proportional to the number of switching cycles can be ignored.

[0024] Furthermore, as shown in Figures 3 and 4, the method of adjusting the current flowing through current paths 20-1 and 20-2 by PWM switching results in periods when no current flows through one of the current paths, reducing the utilization efficiency of the current paths. In other words, since the heat generated in a current path is proportional to the square of the current, if the average current per unit time is the same, continuously flowing a constant current reduces the overall heat generated in the current path compared to intermittently flowing the current. For example, when a current I is continuously flowing and when a current 2I is flowing with a 50% duty cycle, the average current is I in both cases, but since the heat generated is proportional to the square of the current, the heat generated in the former case is I 2 If we denote the latter as R, the heat generated is (2I). 2 R / 2 = 2I 2 The result is R.

[0025] On the other hand, in the embodiment in which the current is adjusted by a control variable resistor rc1 as shown in Figure 2, the control variable resistor is I 2 Heat R is generated. There is no significant difference in the increase in heat generation between the two, but in the embodiment shown in Figure 2, the heat is concentrated in the control variable resistor rc1, so additional costs are incurred for heat dissipation measures such as heat sinks to dissipate the heat. In contrast, in the embodiments shown in Figures 3 and 4, the heat is widely distributed throughout the entire current path, so there is no need to provide a heat sink, and cost reduction can be achieved.

[0026] Figure 5 shows an example of changing the method of adjusting the current flowing through current paths 20-1 and 20-2 depending on the magnitude of the current difference.

[0027] As mentioned earlier, adjusting the current flowing through current paths 20-1 and 20-2 using PWM results in periods where no current flows through one of the current paths, thus reducing the utilization efficiency of the current paths as described above. Therefore, adjusting the current flowing through current paths 20-1 and 20-2 using the output voltages V1 and V2 of the voltage source, so that current always flows through both current paths, improves the utilization efficiency of the current paths and reduces the overall heat generation of the current paths.

[0028] On the other hand, the range in which the output voltages V1 and V2 of a voltage source can be adjusted is limited by factors such as the operating voltage range of the load. For example, the output voltage range of a 12V power source is around 12V (e.g., 12V to 14V), and the output voltage cannot be significantly changed from this range. Ichi Removing the power source can cause malfunctions in the load's operation. Furthermore, while the output voltage can be adjusted when the power source is a switching regulator or DC / DC converter, when the power source is a secondary battery, the output voltage depends on the charge state (SOC), making it impossible to change the output voltage independently.

[0029] Therefore, as shown in Figure 5, if the ratio of currents flowing through current paths 20-1 and 20-2 (I2ave / I1ave) is within a certain range, and the output voltages V1 and V2 can be adjusted within the range of Vmax to Vmin, the currents flowing through current paths 20-1 and 20-2 are adjusted by the output voltages V1 and V2 of the voltage source. If the difference in currents flowing through current paths 20-1 and 20-2 is large, and the output voltages V1 and V2 cannot be adjusted within the range of Vmax to Vmin, the currents flowing through current paths 20-1 and 20-2 are controlled and balanced by PWM switching (setting duty cycles β1 and β2). In this way, by combining PWM and output voltage adjustment, it is possible to reduce the heat generated in the entire current path and optimize efficiency. Note that although Figure 5 shows the current ratio, it is also possible to use the ratio of the heat generated in current paths 20-1 and 20-2.

[0030] Figure 6 is a block diagram showing an example of the configuration of an electronic control unit for realizing the present invention. Power sources 100-1 and 100-2 supply power to electronic control units (ECUs) 200-1 and 200-2, respectively, and electronic control units 200-1 and 200-2 adjust the current flowing through current paths 20-1 and 20-2. Electronic control units 200-1 and 200-2 each have a current detection function or shunt resistors rs1 and rs2 for current detection, control units 110-1 and 110-2 for adjusting the current, and switching elements SW1 and SW2 for switching the current, respectively.

[0031] The control units 110-1 and 110-2 turn on and off the switching elements SW1 and SW2 that switch the current, or control the set values ​​of the output voltages V1 and V2 of the power sources 100-1 and 100-2, based on the values ​​of the currents I1 and I2 flowing through the current paths 20-1 and 20-2 detected by the current detection function or shunt resistors rs1 and rs2 for current detection, their average value, mean square value, and the amount of heat generated in the current paths 20-1 and 20-2 estimated from the values ​​of the currents I1 and I2. The power sources 100-1 and 100-2 and the control units 110-1 and 110-2 are connected by a communication channel 40, through which the set values ​​of the output voltages V1 and V2 of the power sources 100-1 and 100-2, and the values ​​of the currents I1 and I2 are transmitted. The form of the communication channel 40 may be individual wiring or a network.

[0032] An example of the functional configuration of control units 110-1 and 110-2 is shown in Figure 7. As shown in Figure 7(a), control unit 110-1 does not adjust the current flowing through current path 20-1 if the difference between the average values ​​I1ave and I2ave of currents I1 and I2, I1ave-I2ave (hereinafter, ΔI1), is less than the threshold Ith1. If the average current difference ΔI1 is greater than or equal to threshold Ith1 and less than threshold Ith2, current adjustment is performed by controlling the set value of the output voltage V1 of power source 100-1. Furthermore, if the average current difference ΔI1 is greater than or equal to threshold Ith2, current control operation is performed by PWM switching (setting of duty cycle β1).

[0033] Also, as shown in FIG. 7(b), for the control unit 110-2 as well, the current flowing through the current path 20-2 is adjusted according to the magnitude relationship between the average current difference I2ave - I1ave (ΔI2) and the threshold values Ith1 and Ith2. As can be understood from the above, the threshold values Ith1 and Ith2 correspond to the lower limit value and the upper limit value that can adjust the output power of the power sources 100-1 and 100-2.

[0034] Here, g and f shown in FIG. 7 may be functions, and the input-output may have a proportional relationship with a constant proportionality coefficient, or may be a PID control system. Also, when obtaining the average currents I1ave and I2ave, methods such as the integral value of the currents I1 and I2 over a predetermined period or the exponential moving average can be adopted. According to the exponential moving average, the latest exponential moving average value can be obtained by multiplying the calculation results of the past exponential moving average and the current value of the current by coefficients respectively and then adding them. By repeating this operation every predetermined period, the calculation amount can be reduced.

[0035] The operation of the above control unit 110-1 summarized in tabular form is shown in FIG. 8(a). Similarly, the operation of the control unit 110-2 is as shown in FIG. 8(b).

[0036] Also, since the heat generation in the current paths 20-1 and 20-2 is proportional to the square of the current, the control units 110-1 and 110-2 perform operations using the square root mean of the current I1 2 ave, I2 2 ave, which is in a proportional relationship with the heat generation amount on the current paths 20-1 and 20-2, as an index. As shown in FIG. 9(a), when the square root mean difference of the current I1 2 ave - I2 2 ave (hereinafter Δ11 2 ) is less than the threshold value Ith1, since there is no need to adjust the heat generation amounts of both, the current flowing through the current path 20-1 is not adjusted. When Δ1 2 is greater than or equal to the threshold value Ith1 and less than the threshold value Ith2, current adjustment is performed by controlling the set value of the output voltage V1 of the power source 100-1. Further, when Δ1 2 is greater than or equal to the threshold value Ith2, current control operation is performed by PWM switching (setting the duty time β1).

[0037] Furthermore, as shown in Figure 9(b), the control unit 110-2 also controls the mean square difference of the current I2 2 ave-I1 2 ave(Δ12 2 The current flowing through current path 20-2 is adjusted based on the relative magnitudes of the thresholds Th1 and Th2.

[0038] As described above, by balancing the power supply amount (average current, mean square current, total current, temperature rise) among the multiple current paths 20-1 and 20-2 under normal conditions, it is possible to optimize power supply efficiency and reduce the rated capacity required for each of the current paths 20-1 and 20-2. Furthermore, if the power supply amount between current paths 20-1 and 20-2 is not balanced, the reserve power supply capacity will decrease if a failure occurs in the current path with a larger power supply. However, by adjusting the power supply amount between current paths 20-1 and 20-2 in a balanced manner as in this embodiment, it is possible to guarantee the reserve power supply capacity from the other current path in the event of a failure in one current path.

[0039] Furthermore, similarly, under normal conditions, balancing the power capacity (battery charge level, voltage) between current paths 20-1 and 20-2 ensures a reserve capacity for power supply from the other current path in the event of a failure in one current path.

[0040] In the above example, the current paths 20-1 and 20-2 were described as being composed of a single signal line. However, in automotive power supply networks, as shown in Figure 10, current paths are often wired as bundles called wire harnesses, which are bundles of multiple wires and control signal lines. Therefore, the electronic control units 200-1 and 200-2 supply power to multiple wires as shown in Figure 10, detect the currents I11 to I2n flowing through each wire using a current detection function or shunt resistors rs11 to rs2n, and perform current adjustment operations by the control units 110-1 and 110-2 based on these detections.

[0041] Thus, in response to the case where the current path is wired as a bundle of wires called a wire harness, which bundles multiple wires and control signal lines, Figure 11 shows the operation of the control units 110-1 and 110-2, which perform current control operations using the total currents ΣI1 and ΣI2 flowing through current paths 20-1 and 20-2 as indicators.

[0042] The total currents ΣI1 and ΣI2 flowing through current paths 20-1 and 20-2 are, respectively ΣI1=ΣI1j(j is from 1 to m)···(11) ΣI2 = ΣI2j (where j is from 1 to n) ... (12) It can be expressed by the following formula.

[0043] Then, as shown in Figures 11(a) and (b), the control units 110-1 and 110-2 adjust the current flowing through current paths 20-1 and 20-2 based on the relationship between the difference in total currents ΣI1-ΣI2(ΔΣI1) and ΣI2-ΣI1(ΔΣI2) and the thresholds lth1 and lth2.

[0044] Furthermore, the control units 110-1 and 110-2 can also adjust the current using the temperature rise Θ1 and Θ2 in the current paths 20-1 and 20-2 as indicators. Figure 12 shows the operations performed by the control units 110-1 and 110-2 in this case. In this case as well, as in the other examples, the control units 110-1 and 110-2 adjust the current flowing through the current paths 20-1 and 20-2 based on the relationship between the difference in temperature rise Θ1-Θ2(ΔΘ1) and Θ2-Θ1(ΔΘ2) and the thresholds Θth1 and Θth2, as shown in Figures 12(a) and (b). Note that the temperature rises Θ1 and Θ2 may be measured values, but they may also be estimated values ​​based on the currents I1 and I2 or the total currents ΣI1 and ΣI2 flowing through the current paths 20-1 and 20-2.

[0045] Next, one of the two current paths... styleFigure 13 shows the actions taken by control units 110-1 and 110-2 when a fault occurs in the current path. As shown in Figure 13(a), control unit 110-1 is equipped with a switching element SW3 that switches the connection of current path 20-2 to the load. When the status of current path 20-2 is OK, that is, when there is no fault in current path 20-2, control unit 110-1 turns on SW3 to turn on the connection of current path 20-2 to the load and performs the same operation as in the embodiment described above. When the status of current path 20-2 is NG, that is, when there is a fault in current path 20-2, the switching element SW3 selects 0 and disconnects the connection of current path 20-2 to the load. Then, control unit 110-1 supplies power to the load as rated without adjusting the current flowing through current path 20-1. Control unit 110-2, which controls current path 20-2, also performs a similar operation based on the status of current path 20-2, as shown in Figure 13(b). This allows the system to continue operating if a failure occurs in one power supply path, as power can be supplied solely from the other power supply path.

[0046] Furthermore, the current adjustment operation in this embodiment may be performed only when current paths 20-1 and 20-2 overheat, that is, when the measured or estimated temperature of current paths 20-1 and 20-2 is higher than a predetermined threshold, and not performed when they are not overheated, that is, when the measured or estimated temperature of current paths 20-1 and 20-2 is lower than a predetermined threshold.

[0047] Figure 14 shows the operations performed by control units 110-1 and 110-2 in this case. As shown in Figure 14(a), control unit 110-1 performs the current adjustment described in Figure 8, etc., when the current path 20-2 is normal, i.e., there is no fault and it is overheating. However, it does not perform the current limiting operation when the current path 20-2 is abnormal, i.e., there is a fault, or when the current path 20-2 is not overheating. Similarly, control unit 110-2 performs the operations shown in Figure 14(b) as shown by control unit 110-1.

[0048] According to this embodiment, there is no need to adjust the current when there is no overheating, and adjustment is only necessary when it is estimated that there is a large difference in the current flowing through the current path, thus simplifying operation.

[0049] Figure 15 shows an example of an in-vehicle power supply network equipped with a power supply system according to one embodiment of the present invention. As shown in Figure 15, in a vehicle equipped with the power supply system according to one embodiment, power is supplied to critical loads such as the steering ECU 200-5, the automatic driving (AD) ECU 200-6, and a central gateway (not shown) that mediates communication between each ECU, from multiple power sources 100-1 and 100-2 via electronic control units 200-1 and 200-2 and current paths 20-1 and 20-2, respectively. Furthermore, even if a failure occurs in any of the power sources 100-1 and 100-2, electronic control units 200-1 and 200-2, or current paths 20-1 and 20-2, and power supply from one of the current paths stops, the operation of the critical loads can be continued by performing the operations described in Figures 13 and 14 and supplying power from the other current path.

[0050] Furthermore, most non-critical loads, other than critical loads, are supplied with power from only one of the current paths 20-1 or 20-2. Non-critical loads include heat pumps, heaters, electric fans, and body systems for entertainment systems and air conditioning (Climate Control). Under normal conditions, i.e., when there is no fault in the current path, power is supplied to both critical and non-critical loads from current paths 20-1 and 20-2, and the power supply to non-critical loads creates a difference in the current flowing through current paths 20-1 and 20-2. However, by adjusting the power supply to critical loads, which are supplied with power from both current paths 20-1 and 20-2, according to the present invention, the amount of power supplied from current paths 20-1 and 20-2 can be balanced. In addition, if a fault occurs in either current path 20-1 or 20-2, power is supplied to the critical load from the other current path, and the power supply to non-critical loads is reduced or stopped, thereby allowing for a margin in the power supply capacity of the normal current path. In particular, heat pumps, heaters, and electric fans have relatively large thermal time constants, so the impact of short-term shutdowns is often minimal.

[0051] The following describes specific examples of how to supply power to critical loads such as the steering ECU 200-5 and the autonomous driving ECU 200-6 from both current paths 20-1 and 20-2. In the simplest method, as shown in Figure 15, current is supplied to the critical loads via diodes. SupplementThe voltage is supplied. Furthermore, if the main part of the ECU200, such as a microcontroller, operates on a stepped-down voltage, for example, 5V from a 12V system, it is conceivable to provide multiple voltage-stepping regulators 300-1 and 300-2, as shown in Figure 16, and supply the stepped-down voltage output from regulators 300-1 and 300-2 to the ECU200 via diodes. Also, as shown in Figure 17, if multiple microcontrollers 210-1 and 210-2 are provided to ensure redundancy of the microcontrollers constituting the ECU200, it is conceivable to supply the stepped-down voltage output from multiple regulators 300-1 and 300-2, independently provided for each current path 20-1 and 20-2, to the respective microcontrollers 210-1 and 210-2. Note that in the case of Figure 17, unlike Figure 16, the regulators 300-1 and 300-2 and the microcontrollers 210-1 and 210-2 are directly connected without diodes.

[0052] Furthermore, Figure 18 shows an example of a switching power supply 310 that steps down the voltage by switching the power from multiple current paths 20-1 and 20-2 using switching elements SW1 and SW2. In this embodiment, the output voltage can be controlled by changing the switching duty cycle of switching elements SW1 and SW2, and the current from current paths 20-1 and 20-2 can be controlled by creating a difference in the switching duty cycle of switching elements SW1 and SW2. L is a choke coil for smoothing, C is a capacitor for smoothing, and D is a freewheeling diode.

[0053] Figure 19 shows a more detailed configuration of the switching power supply 310. The difference between the output voltage and the reference voltage Vref is input to the control units CNTRL1 and CNTRL2 of the switching power supply 310, and feedback control is performed so that the difference between the output voltage and the reference voltage Vref becomes 0. Here, a signal with the duty offset added is input to CNTRL2, so that the switching element SW2 switches with a different duty cycle than the switching element SW1, and the currents I1 and I2 from the current paths 20-1 and 20-2 can be set to different values.

[0054] Figure 20 shows a more detailed configuration of the switching power supply 310. The control units CNTRL1 and CNTRL2 of the switching power supply 310 can be composed of comparators CMP1 and CMP2 that compare the input signal with the output of the sawtooth wave or triangular wave generating circuit OSC. By comparing the input signal with the output of the sawtooth wave or triangular wave generating circuit OSC, CMP1 and CMP2 drive SW1 and SW2 at a predetermined duty cycle, so that the currents I1 and I2 from the current paths 20-1 and 20-2 can be set to different values.

[0055] Furthermore, as shown in Figure 21, if the output of the sawtooth wave or triangular wave generating circuit OSC is inverted by the inverting amplifier 320 and input to the comparator CMP2, the switching elements SW1 and SW2 will switch alternately in opposite phases. As a result, the switching frequency, or ripple frequency, will be doubled, and the product of L and C will be halved. This allows for smaller values ​​of L and C, leading to cost reduction.

[0056] Furthermore, the switching power supply 310 according to this embodiment can be used not only for step-down conversion from 12V to 5V, but also when the main power supply system between ECU200-1 to 200-3 is set to a medium voltage of 24V to 48V, as shown in Figure 22, and the terminal power supply system to the terminal loads connected to each ECU (for example, ECU200-3) is supplied with 12V stepped down from the main power supply system.

[0057] The embodiments of the present invention described above provide the following effects. (1) The power supply system according to the present invention comprises a plurality of power sources that supply power to a single load in a vehicle, a plurality of power supply paths that connect the single load to each of the plurality of power sources, and a current adjustment unit that adjusts the current flowing through the plurality of power supply paths, adjustment The unit compares the state quantities of the electrical states of each power supply path, and when the difference between these state quantities satisfies a predetermined condition, it adjusts the current flowing through the power supply path to reduce the difference between these state quantities.

[0058] With the above configuration, power can be supplied to the load even if a failure occurs in one of the current paths, making it possible to continue the operation of particularly critical loads. Furthermore, when no failure occurs in the current paths and everything is functioning normally, the power supply can be evenly distributed among the multiple current paths, thereby reducing the capacity required for each current path.

[0059] (2) The current adjustment unit adjusts the current flowing through each of the multiple power supply paths. This makes it possible to handle situations where there are multiple power supply paths and it is necessary to adjust the power for each of them.

[0060] (3) The current adjustment unit adjusts the current flowing through each of the multiple power supply paths by pulse width modulation with different duty cycles. This makes it possible to set the duty cycle appropriately and optimize the utilization efficiency of the power supply paths.

[0061] (4) Of the multiple power supply paths, at least some of the on-periods of the current flowing through multiple power supply paths overlap. As a result, current is always flowing through at least one of the power supply paths, so even if the current in one of the current paths is interrupted, the current in the entire circuit does not abruptly drop to zero, thus eliminating the need for freewheeling diodes, choke coils, etc. that are required in a normal switching regulator.

[0062] (5) Flows through some of the power supply paths among multiple power supply paths Current The duty cycle is 100%. This reduces the heat generated in this power supply path compared to a PWM-controlled power supply path, thus reducing the overall heat generation of the circuit.

[0063] (6) The pulse width modulation period is smaller than the thermal time constant of the power supply path. Specifically, a slow period of several hundred ms to several seconds is sufficient. Therefore, it becomes possible to ignore the increase in switching losses that is proportional to the number of switching cycles.

[0064] (7) The present invention has a voltage converter that converts multiple input powers from multiple power supply paths into a single output power of a different voltage from the input powers, and pulse width modulation is performed by the voltage converter. The interior of an automobile is composed of, for example, a main power supply system with an operating voltage of 24 to 48V, a terminal power supply system of 12V, and various ECUs of 5V, and the effectiveness of the present invention in the automotive field is ensured in the same manner as described above.

[0065] (8) The system further comprises an electronic control unit connected to the power source side of each of the multiple power supply paths, and pulse width modulation is performed by the electronic control unit. The electronic control unit also has a function to measure the current flowing through the multiple power supply paths and / or a function to estimate the temperature of the multiple power supply paths. The present invention is suitably applicable to automobiles having a zone architecture configuration or the like, which have been under development in recent years.

[0066] (9) The electrical condition is the temperature of the wiring resistance of the power supply path, and the capacity or voltage of the power supply connected to the power supply path. This makes it possible to monitor the condition of the power supply path from various viewpoints and to adopt an appropriate method for adjusting the current.

[0067] (10) Each power supply path consists of a bundle of multiple cables tied together. The present invention is suitably applicable to objects having such a configuration, such as automobiles.

[0068] (11) If a failure occurs in part of multiple power supply paths, power will be supplied only from the other power supply paths. The power supply system Because they are configured to complement each other, they can prevent interruptions in the power supply to critical loads.

[0069] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible. For example, the embodiments described above are explained in detail to make the present invention easier to understand, and the present invention is not necessarily limited to embodiments having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment. It is also possible to add configurations from other embodiments to the configuration of one embodiment. Furthermore, it is possible to delete parts of the configuration of each embodiment, or to add or replace other configurations. [Explanation of Symbols]

[0070] 20-1, 20-1...Current path (power supply path), 30...Load, 100-1, 100-2...Power source, 110-1, 110-2...Control unit (current adjustment unit), 200-1, 200-2...Electronic control unit, 300-1, 300-2...Regulator (voltage converter)

Claims

1. Multiple power sources supplying power to a single load within the vehicle, Multiple power supply paths connecting the single load and each of the multiple power sources, A current adjustment unit that adjusts the current flowing through at least one of the aforementioned multiple power supply paths, Equipped with, The current adjustment unit compares the state quantities of the electrical states of each of the power supply paths, and when the difference in the state quantities satisfies a predetermined condition, it adjusts the current flowing through each of the plurality of power supply paths to reduce the difference in the state quantities. At least some of the power supply paths mentioned above have overlapping on periods for the currents flowing through them. A power supply system characterized by the following features.

2. Multiple power sources that supply power to a single load inside a vehicle, Multiple power supply paths connecting the single load and each of the multiple power sources, A current adjustment unit that adjusts the current flowing through at least one of the aforementioned multiple power supply paths, Equipped with, The current adjustment unit compares the state quantities of the electrical states of each of the power supply paths, and when the difference in the state quantities satisfies a predetermined condition, it adjusts the current flowing through each of the plurality of power supply paths by pulse width modulation of different duty cycles so as to reduce the difference in the state quantities. The duty cycle of the current flowing through some of the aforementioned power supply paths is 100%. A power supply system characterized by the following features.

3. Multiple power sources that supply power to a single load inside a vehicle, Multiple power supply paths connecting the single load and each of the multiple power sources, A current adjustment unit that adjusts the current flowing through at least one of the aforementioned multiple power supply paths, Equipped with, The current adjustment unit compares the state quantities of the electrical states of each of the power supply paths, and when the difference in the state quantities satisfies a predetermined condition, it adjusts the current flowing through each of the plurality of power supply paths by pulse width modulation of different duty cycles so as to reduce the difference in the state quantities. The period of the pulse width modulation is smaller than the thermal time constant of the power supply path. A power supply system characterized by the following features.

4. A power supply system according to claim 1, The aforementioned electrical state is the temperature of the wiring resistance of the power supply path. A power supply system characterized by the following features.

5. A power supply system according to claim 1, The aforementioned electrical state is the capacity of the power supply connected to the power supply path. A power supply system characterized by the following features.

6. A power supply system according to claim 1, The aforementioned electrical state is the voltage of the power supply connected to the power supply path. A power supply system characterized by the following features.

7. A power supply system according to claim 1, Each of the aforementioned power supply paths consists of a bundle of wires in which multiple cables are tied together. A power supply system characterized by the following features.

8. A power supply system according to claim 1, If a failure occurs in one of the aforementioned multiple power supply paths, power will be supplied only from the other aforementioned power supply paths. A power supply system characterized by the following features.

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