Vehicle power supply unit

Abstract

To provide a power supply device for a vehicle capable of inexpensively and surely preventing electric shock.SOLUTION: A power supply device 1 for a vehicle includes: a first power storage element group 2 in which a plurality of power storage elements are connected in series; a second power storage element group 3 that is connected in series to a positive electrode side of the first power storage element group and constitutes a high-voltage DC power supply by being combined with the first power storage element group; an active balancer 4; first switch means 5 and second switch means 6 arranged between the first power storage element group and a low-voltage load; control means 7; cutoff means 8 for cutting off power of a high-voltage DC power supply; and leakage detection means 9. The control means determines a signal sent from the leakage detection means 9 during a dead time period when the first switch means 5 and the second switch means 6 are in an OFF state, and cuts off power to be supplied to the load for a predetermined period when a leakage current reaches a predetermined reference.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle power supply device, and more particularly to a vehicle power supply device that supplies power to a plurality of loads that operate at different voltages, and that has a simple configuration and can reliably protect the user from electric shock. [Background technology]

[0002] Conventionally, automotive electrical circuits have been divided into two systems: one that supplies low-voltage power from a 12V or 24V lead-acid battery, and one that supplies high-voltage power from a secondary drive battery of around 300V to 400V. Lead-acid batteries are heavy, and their manufacture and disposal place a heavy burden on the environment. Furthermore, recent electric and hybrid vehicles may require higher-voltage power supplies. For this reason, development is underway on secondary battery systems that can provide different voltages from a single power source for vehicles.

[0003] Secondary battery systems widely use secondary batteries with multiple storage elements connected in series. Increasing the number of storage elements allows these secondary batteries to obtain a high output voltage, enabling efficient power supply. However, strict measures to prevent electric shock are required for on-board power supplies. Safety measures are particularly essential for power systems with operating voltages of DC 60V or higher.

[0004] The inventors previously invented and disclosed in Patent Document 1 a vehicle power supply device that obtains low-voltage power from a high-voltage power supply via a step-down means and that can prevent electric shock to humans without using an insulating means such as a transformer. The basic configuration of the vehicle power supply device in Patent Document 1 is shown in Figure 5. The vehicle power supply device supplies power to an electrical load 300 operating at 12 V and a high-voltage load device 400 from a high-voltage power supply 600 composed of multiple storage elements. The vehicle power supply device includes multiple switch means that connect some of the storage elements in the high-voltage power supply 600 to the electrical load 300. The switch means are selectively switched at a cycle of approximately 100 usec to supply power of a predetermined voltage to the electrical load. The voltage balance between the storage elements is controlled by controlling the connection time of the switch means. The vehicle power supply device in Patent Document 1 also includes a leakage current detection means 100 that detects leakage current between the high-voltage power supply and ground potential. The leakage current detection means 100 detects the presence or absence of leakage during the dead time when all of the switch means are off. The leakage current detection means measures the leakage current between the high voltage power supply and the ground electrode, for example. When the leakage current detected by the leakage current detection means is greater than 0 amperes, the control means determines that a leakage current has occurred and prohibits subsequent connection of the switch means or turns off the interrupting means 500, 501 to prevent electric shock.

[0005] The inventors also invented a high-voltage power supply characterized in that, in a secondary battery comprising multiple batteries connected in series, an output terminal provided between the batteries is grounded, and disclosed this in Patent Document 2. An example of the configuration of the high-voltage power supply in Patent Document 2 is shown in FIG. 6. High-voltage power supply 124 includes multiple batteries 111 connected in series, each of which contains multiple energy storage elements. An output terminal between the batteries 111 is connected to ground 105 of the vehicle body and is at ground potential. This reduces the maximum potential difference between high-voltage power supply 124 and ground 105, eliminating the need for insulation from the vehicle body even when supplying power to high-voltage load device 103. High-voltage power supply 124 also includes balancers 132 connected in parallel with all of the batteries 111 to form bypass circuits, actively controlling the balance between the charge and discharge states of the multiple batteries 111.

[0006] The vehicle power supply device of Patent Document 1, when using a typical 3V storage element, requires 100 storage elements and 50 switch means to supply power to a load device with a high voltage rating of 300V. Providing a large number of switch means increases the cost of the entire device and complicates control. On the other hand, when supplying power to a load device with a voltage rating of 300V, the high-voltage power supply of Patent Document 2 requires a potential difference of at least 150V between the high-voltage power supply 124 and ground 105. This necessitates the same electric shock prevention measures as in conventional devices. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 2021-114847 [Patent Document 2] Japanese Patent Application Publication No. 2020-199925 Summary of the Invention [Problem to be solved by the invention]

[0008] A vehicle power supply system must provide reliable insulation between various electrical circuits and the vehicle body, which users may come into contact with. However, in the case of a power supply system that includes multiple voltage systems, the device configuration for voltage control and insulation tends to be large and expensive.

[0009] The present invention has been made in consideration of the above problems, and has been made with the aim of solving the problem of providing a vehicle power supply device that can supply power at multiple voltages and also provide reliable insulation measures. [Means for solving the problem]

[0010] The present invention relates to a vehicle power supply device that supplies power to a low-voltage load and a high-voltage load driven at a higher voltage than the low-voltage load. The vehicle power supply device of the present invention includes: a first group of storage elements connected in series to obtain a DC power supply of a predetermined voltage; a second group of storage elements also connected in series to the positive electrodes of the first group of storage elements and constituting a high-voltage DC power supply together with the first group of storage elements; an active balancer disposed between the first group of storage elements; interrupting means for interrupting power from the high-voltage DC power supply; control means; and leakage detection means. The control means controls first and second switch means to obtain a predetermined low voltage, controls the active balancer to substantially equalize the capacities of all the storage elements, and controls switching of the interrupting means. The leakage detection means detects leakage current between the high-voltage DC power supply and ground potential and sends a signal to the control means. The control means of the present invention is characterized in that it judges the signal sent from the leakage current detection means during the dead time period when the first switch means and the second switch means are in the off state, and if the leakage current reaches a predetermined standard, it cuts off power to either or both of the low voltage load and the high voltage load for a predetermined period of time.

[0011] In the vehicle power supply device of the present invention, it is preferable that the active balancer is connected to three points: the cathode side of the first storage element group, the positive side of the second storage element group, and an output terminal provided between the first storage element group and the second storage element group.

[0012] The control means of the vehicle power supply device of the present invention can fix the interrupting means in the OFF state when the leakage current reaches a predetermined standard.

[0013] Furthermore, the control means of the vehicle power supply device of the present invention can repeat the operation of keeping the interrupting means in an off state for a predetermined time when the leakage current reaches a predetermined standard, and then turning the interrupting means on again.

[0014] The control means of the vehicle power supply device of the present invention can control the switching means so that the product of the period during which the first switch means and the second switch means are connected to the low voltage load and the leakage current detection value of the leakage current detection means is 0.003 amperes x 1 second or less.

[0015] The control means of the vehicle power supply device of the present invention can inhibit the connection of the first switch means and the second switch means when the leakage current reaches a predetermined standard.

[0016] In the vehicle power supply device of the present invention, the reference current value for the leakage current can be set to 0 amperes. When the leakage current is greater than 0 amperes, the control means preferably cuts off power to either or both of the low-voltage load and the high-voltage load for a predetermined period of time. [Effects of the Invention]

[0017] The vehicle power supply device according to the present invention can provide both high-voltage and low-voltage power. The low-voltage is supplied from the first storage element group via first and second switch means. Because the device does not require a DC-DC converter or numerous switch means, which were previously required to obtain the low voltage from a high-voltage power supply, the overall device configuration can be simplified and made more inexpensive than in the past.

[0018] The withstand voltage of the first switch means and the second switch means of the vehicle power supply device according to the present invention may be a voltage corresponding to the voltage output from the first group of power storage elements, and switch means compatible with lower voltages may be used, which further simplifies the overall configuration of the device and allows the device to be constructed inexpensively.

[0019] On the other hand, in the vehicle power supply device of the present invention, the electric shock prevention processing unit of the control means judges the signal sent from the leakage current detection means during the dead time period when the first switch means and the second switch means are in the off state, and if the leakage current reaches a predetermined standard, it takes reliable measures against electric shock by cutting off power to either or both of the low voltage load and the high voltage load for a predetermined period of time, thereby ensuring safety.

[0020] In particular, the control means outputs a command to turn off the cut-off means at an appropriate timing and for an appropriate period, and the cut-off means cuts off the current in response to the command, thereby stopping the power supply from the high-voltage DC power source and providing reliable protection against electric shock around the high-voltage system and high-voltage load.

[0021] Furthermore, the control means outputs a command to prohibit the first switch means and the second switch means from being connected and turned off, thereby stopping the supply of low-voltage power and providing reliable protection against electric shock around the low-voltage system and low-voltage loads. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a block diagram that schematically shows a state in which a vehicle power supply device of the present invention is connected to a plurality of loads. [Figure 2] FIG. 2 is a diagram showing a schematic diagram of the control of the state of charge by the active balancer. [Figure 3] FIG. 3 is a diagram illustrating an example of leakage detection in the vehicle power supply device according to the embodiment of the present invention. [Figure 4] FIG. 4 is a diagram illustrating an alternative example of leakage detection in a vehicle power supply device according to an embodiment of the present invention. [Figure 5] FIG. 5 is a block diagram showing a schematic configuration of a conventional high-voltage power supply. [Figure 6] FIG. 6 is a block diagram showing a schematic configuration of a conventional high-voltage power supply. DETAILED DESCRIPTION OF THE INVENTION

[0023] Preferred embodiments of a vehicle power supply device of the present invention will now be described with reference to the drawings. Figure 1 is a block diagram showing an example of the configuration of a vehicle power supply device 1 according to one embodiment. The vehicle power supply device 1 in this embodiment supplies power to a low voltage load 20 and a high voltage load 30.

[0024] The vehicle power supply device 1 includes a first group of storage elements 2, a second group of storage elements 3, an active balancer 4, a first switching means 5, a second switching means 6, a control means 7, a breaker means 8, and a leakage current detection means 9.

[0025] The first storage element group 2 is a group of storage elements that serves as the power source for the low-voltage load 20. The first storage element group 2 is configured by connecting multiple secondary batteries, each of which can be charged and discharged, in series. The storage elements can be configured with battery cells, such as lithium-ion batteries or nickel-metal hydride batteries, and are charged by a power generation means installed in the vehicle or an external power source.

[0026] The second energy storage element group 3, in combination with the first energy storage element group 2, constitutes a high-voltage power supply that serves as the power source for the high-voltage load 30. The second energy storage element group 3 is connected in series to the positive electrode side of the first energy storage element group 2. The energy storage elements that constitute the second energy storage element group 3 are preferably configured from the same secondary battery cells, such as lithium-ion batteries or nickel-metal hydride batteries, as the energy storage elements of the first energy storage element group 2. The second energy storage element group 3 is also charged by a power generation means installed in the vehicle or an external power source.

[0027] In particular, the first energy storage element group 2 often has a lower remaining capacity than the second energy storage element group 3 due to power supply to the low-voltage load 20. The active balancer 4 is disposed between the first energy storage element group 2 and the second energy storage element group 3, and makes the state of charge (SOC) of the energy storage elements, i.e., the remaining capacity relative to the maximum capacity of each energy storage element, approximately uniform. The active balancer 4 is preferably connected to three points: the cathode side of the first energy storage element group 2, the positive side of the second energy storage element group 3, and an output terminal provided between the first energy storage element group 2 and the second energy storage element group 3.

[0028] The first switch means 5 and the second switch means 6 are arranged on a wiring that supplies power from the first storage element group 2 to the low voltage load 20, and when both the first switch means 5 and the second switch means 6 are on, power is supplied to the low voltage load 20. The on and off timings of the first switch means 5 and the second switch means 6 are controlled by the control means 7.

[0029] In a preferred embodiment, a capacitor 21 is arranged in parallel with the low voltage load 20. During the period when both the first switch means 5 and the second switch means 6 are turned off by the control means 7, the power supply from the first power storage element group 2 to the low voltage load 20 is momentarily interrupted, which may cause the low voltage load 20, which is an electrical load of the vehicle, to momentarily stop. However, by providing the capacitor 21, the power charged in the capacitor 21 continues to be supplied to the low voltage load 20 even when the first switch means 5 and the second switch means 6 are turned off, and the voltage does not drop to 0 volts, but can be kept to a slight voltage drop.

[0030] The interrupter 8 includes a first shutoff switch 81 and a second shutoff switch 82, and is disposed on the wiring that supplies power to the high-voltage load 30 from the first storage element group 2 and the second storage element group 3. As shown in the upper part of Fig. 3, the first shutoff switch 81 and the second shutoff switch 82 are turned on for a period TS and turned off for a certain period, and this operation is repeated in a cycle TS. While the first shutoff switch 81 and the second shutoff switch 82 are on, the high-voltage power supply consisting of the first storage element group 2 and the second storage element group 3 is supplied to the high-voltage load 30, and while the shutoff means 500, 501 are off, the high-voltage load 30 is disconnected from the high-voltage power supply.

[0031] The leakage detection means 9 is disposed between the high-voltage DC power supply and the high-voltage load 30. The leakage detection means 9 has a terminal T1 connected to the anode side of the second energy storage element group 3 and a terminal T2 connected to the cathode side of the first energy storage element group 2. The leakage detection means 9 is also grounded to the vehicle body via a terminal T3. Furthermore, the leakage detection means 9 is communicatively connected to the control means 7 via a terminal T0.

[0032] The control means 7 monitors and controls the entire vehicle power supply device 1. In particular, the control means 7 controls the first switch means 5 and the second switch means 6 to obtain a predetermined low voltage, and cuts off power to the low-voltage load as necessary when a leak is detected. The control means 7 also controls the active balancer 4 to control the charge states of all the storage elements to be approximately uniform. Furthermore, the control means 7 performs switching control of the cutoff means 8 based on the output of the leak detection means 9.

[0033] The control means 7 controls the first switch means 5 and the second switch means 6 at a predetermined frequency and duty ratio. When both the first switch means 5 and the second switch means 6 are turned on, power is supplied to the low voltage load 20. The control means 7 simultaneously switches the first switch means 5 and the second switch means 6, thereby making it possible to output stabilized low voltage power.

[0034] The control means 7 controls the active balancer 4 to control the charge and discharge states of the first energy storage element group 2 and the second energy storage element group 3. The active balancer 4 is connected to three points: the cathode side of the first energy storage element group 2, the positive side of the second energy storage element group 3, and an output terminal provided between the first energy storage element group 2 and the second energy storage element group 3. The active balancer 4 has a switch element 41 on the cathode side of the first energy storage element group 2 and a switch element 42 on the positive side of the second energy storage element group 3. The on / off of these switch elements 41 and 42 is controlled with a duty ratio corresponding to the number of energy storage elements, and power is supplied from the power generation means, thereby making the charge states of all the energy storage elements approximately uniform during operation.

[0035] As an example, the charge / discharge control performed by the active balancer 4 will be described below in the case where the same type of energy storage elements are used in the first energy storage element group 2 and the second energy storage element group 3, and the ratio of the number of energy storage elements in the first energy storage element group 2 and the second energy storage element group 3 is 1:3. As shown in Fig. 2, by setting the period during which the switch element 41 is turned on and the switch element 42 is turned off at the same time to be approximately three times the period during which the switch element 41 is turned off and the switch element 42 is turned on at the same time, the time for charging the first energy storage element group 2 can be extended, and the charge states of the first energy storage element group 2 and the second energy storage element group 3 can be made approximately uniform. In this case, the active balancer 4 operates in the same manner as a buck-boost chopper.

[0036] Furthermore, the control means 7 judges the signal sent from the leakage current detection means 9 during the dead time period when the first switch means 5 and the second switch means 6 are in the OFF state, and if the leakage current reaches a predetermined standard, cuts off power to either or both of the low voltage load 20 and the high voltage load 30 for a predetermined period. The detection of the leakage current by the control means 7 must be performed during the dead time period when the first switch means 5 and the second switch means 6 are in the OFF state. This is because when the first switch means 5 and the second switch means 6 are in the ON state, the overall resistance value is low, which reduces the accuracy of detection of the leakage current.

[0037] The operation of the circuit breaker 8 and the earth leakage detection means 9 will be described below with reference to Figures 1, 3, and 4. The upper parts of Figures 3 and 4 show the on / off switching of the first circuit breaker switch 81 and the second circuit breaker switch 82 of the circuit breaker 8 in chronological order. The middle parts of Figures 3 and 4 show the on / off switching of the first switch means 5 and the second switch means 6 in chronological order. The lower parts of Figures 3 and 4 show the relationship between the earth leakage detection value ILeak detected by the earth leakage detection means 9 and the reference value ILeak of earth leakage current pre-stored in the control means 7 in chronological order. The earth leakage detection means 9 is configured to output the larger earth leakage detection value ILeak of the current flowing between terminal T1 and ground terminal T13 and the current flowing between terminal T2 and ground terminal T3 from terminal T0 to the control means 7.

[0038] While the first switch means 5 and the second switch means 6 are off, terminals T1 and T2 are floating with respect to the vehicle body, and the leakage current detection value is 0 amperes. However, when a human body touches the positive electrode side of the second storage element 3, i.e., the T1 side, a leakage current is detected between terminal T2 and ground terminal T3 because the resistance value of the human body is about 5 kΩ.

[0039] 3, when the human body is not in contact with a high-voltage part, the leakage detection value ILeak of the leakage detection means 9 is 0 amperes during the dead time periods Td1 and Td2 when the first switch means 5 and the second switch means 6 are off. However, if the human body touches a high-voltage part while the first switch means 5 and the second switch means 6 are on, the leakage detection value ILeak of the leakage detection means 9 becomes greater than 0 amperes during the dead time period Td3 when the first switch means 5 and the second switch means 6 are off.

[0040] The control means 7 receives the leakage current detection value ILeak via the terminal T0 of the leakage current detection means 9. If the received ILeak is detected to be equal to or greater than a predetermined value ILth, it determines that a leakage current has occurred due to human contact or an equipment malfunction. Then, as shown in Figures 3 and 4, the first cutoff switch 81 and the second cutoff switch 82 of the cutoff means 8 are turned off for a predetermined period of time.

[0041] As shown in Fig. 3, the control means 7 may not specify a period, and the cutoff means 8 may thereafter maintain the OFF state. On the other hand, a vehicle may experience temporary leakage current not only when a human body touches a high-voltage circuit, but also due to leakage from mounted electronic components, malfunction of insulating parts, vibrations while driving, etc. In such cases, if the power supply to the high-voltage load 30 is completely stopped by the action of the control means 7, various parts may lose function while the vehicle is driving, which may be dangerous.

[0042] Therefore, as shown in FIG. 4, the control means 7 can be configured so that when the leakage current detection value ILeak of the leakage current detection means 9 is equal to or greater than a predetermined current value ILth, the control means 7 keeps the first shutoff switch 81 and the second shutoff switch 82 of the shutoff means 8 in an off state for a predetermined period of time, and then repeats the operation of turning on the first shutoff switch 81 and the second shutoff switch 82 again.

[0043] As a result, even if a temporary leakage current occurs due to a failure in any part of the vehicle's power supply device, power supply to high voltage load 30 is resumed from the high voltage power supply consisting of first power storage element group 2 and second power storage element group 3, so vehicle functions are restored and driving safety can be maintained. Furthermore, if the interrupter 8 is kept in the off state for, for example, 0.5 seconds or more, fatal effects on the human body can be prevented even if the leakage current is not due to a vehicle malfunction but is actually due to electric shock to the human body.

[0044] When the first shutoff switch 81 and the second shutoff switch 82 are turned on again, if the leakage current detection value ILeak of the leakage current detection means 100 during the dead time period Tdn exceeds ILth, the control means 7 determines that the human body is still in contact with the high voltage circuit and turns the first shutoff switch 81 and the second shutoff switch 82 off again.

[0045] When the first shut-off switch 81 and the second shut-off switch 82 are turned on again, if the leakage current detection value ILeak of the leakage current detection means 9 during the dead time period Tdn is less than ILth, the control means 7 determines that the human body is not in contact with the high-voltage circuit, and maintains the on state of the first shut-off switch 81 and the second shut-off switch 82 to resume the supply of power to the high-voltage load device 400.

[0046] The high voltage power supply consisting of the first energy storage element group 2 and the second energy storage element group 3 is cut off by the cutoff means 8, so that high voltage current does not flow through the human body, thereby preventing electric shock. Note that the vehicle power supply device 1 is enclosed in a housing (not shown), thereby preventing electric shock caused by the human body coming into contact with the inside of the vehicle power supply device 1.

[0047] In addition, the current interruption process performed by the control means 7 can be either or both of a process of prohibiting the connection of both the first interruption switch 81 and the second interruption switch 82 of the interruption means 8, and a process of prohibiting the connection of both the first switch means 5 and the second switch means 6, depending on the operating states of the low voltage load 20 and the high voltage load 30, respectively. [Example]

[0048] The following is a detailed description of the configuration and operation of a vehicle power supply device 1 that supplies power to a 12V low-voltage load 20 and a 300V high-voltage load 30 provided in a vehicle. The low-voltage load 20 to be supplied with power is, for example, an electric power steering device or a wireless door lock device. The high-voltage load 30 to be supplied with power is, for example, a vehicle traction motor.

[0049] In this embodiment, the first energy storage element group 2 and the second energy storage element group 3 use the same type of lithium ion batteries with a charging voltage of 3V. The first energy storage element group 2 has five lithium ion batteries connected in series. The second energy storage element group 3 has 95 lithium ion batteries connected in series. The first energy storage element group 2 is a DC power source with a maximum voltage of 15V. Furthermore, by combining the first energy storage element group 2 and the second energy storage element group 3, a DC power source with a maximum voltage exceeding 300V is formed.

[0050] Because the first storage element group 2 supplies power to both the low-voltage load 20 and the high-voltage load 30, the charge rate of the first storage element group 2 is often lower than that of the second storage element group 3. Therefore, the active balancer 4 operates the switch elements 41 and 42 in the balancing circuit at different timings and cycles, and maintains an equal state of charge of each storage element group through an operation similar to that of a buck-boost chopper. As an alternative example, the active balancer 4 may operate to transfer the charge of the batteries in the second storage element group 3 to the batteries in the first storage element group 2. Such an active balancer 4 includes multiple transformers, multiple diodes, and switches, and generates current from a primary-side transformer, which is a series-connected multiple transformers, to a secondary-side transformer connected to a storage element group with a low charge level, thereby charging the secondary-side transformer.

[0051] In this embodiment, the first switch means 5 and the second switch means 6 can be switching elements that support a maximum voltage of 15 V output by the first storage element group 2. Therefore, there is no need to use expensive switches that support high voltages as the first switch means 5 and the second switch means 6, and transistors such as MOSFETs can be used.

[0052] The first shutoff switch 81 and the second shutoff switch 82 of the shutoff means 8 may be semiconductor switches with a withstand voltage of 300V or the like.

[0053] The ground terminal T3 of the leakage current detection means 9 is grounded by being connected to the vehicle body. During a period when both the first switch means 5 and the second switch means 6 are off, the anode terminal T1 and cathode terminal T2 of the leakage current detection means 9 are each floating with respect to the vehicle body, maintaining a reference potential. For this reason, the detected current value of the leakage current detection means 9 is normally 0 amperes. However, if a human body touches a high-voltage part while the first switch means 5 and the second switch means 6 are on, the leakage current detection value ILeak of the leakage current detection means 9 during the dead time period Td3 when the first switch means 5 and the second switch means 6 are off will be greater than 0 amperes.

[0054] The control means 7 receives the leakage current ILeak output from the leakage detection means 9 and compares it with a pre-stored reference current value ILth. The reference current value ILth with the highest safety factor is 0 amperes. However, it is generally believed that if the electric shock duration is 0.1 seconds or less when the current value is 30 milliamperes, there will be no fatal human reaction. In this embodiment, from the practical standpoint of preventing electric shock, the reference voltage value ILth is set so that the maximum value of the product of the electric shock current and the electric shock duration is 0.003 ampere-seconds.

[0055] In the vehicle power supply device 1 of this embodiment, the maximum electric shock current can be assumed to be approximately 60 milliamperes, based on a voltage value of 300 volts from the high-voltage power supply and a human body resistance of 5 kΩ. Therefore, the duration of an electric shock that will not harm the human body is estimated to be 0.05 seconds or less. Therefore, in this embodiment, the maximum value of the period TN during which the first shutoff switch 81 and the second shutoff switch 82 are on is set to a sufficiently small value of 0.001 seconds.

[0056] The current cutoff command output by the control means 7 can be a process for prohibiting the connection of both the first cutoff switch 81 and the second cutoff switch 82 of the cutoff means 8. By prohibiting the connection of the cutoff means 8, power supply to the high voltage load 30 is stopped, thereby preventing electric shock. In addition, the current cutoff command output by the electric shock prevention processing unit can be a process for prohibiting the connection of both the first switch means 5 and the second switch means 6. Furthermore, it is also possible to simultaneously perform both the process for prohibiting the connection of the cutoff means 8 and the process for prohibiting the connection of both the first switch means 5 and the second switch means 6.

[0057] When the current cutoff command of the control means 7 is set to turn off the first cutoff switch 81 and the second cutoff switch 82 of the cutoff means 8 for a predetermined period, it is preferable to arrange a capacitor (not shown) with a desired capacity in parallel with the high voltage load 30 so that the voltage supplied to the high voltage load 30 can be maintained even during this stop period.

[0058] When the control means 7 in this embodiment detects that the taken-in ILeak is equal to or greater than a predetermined value ILth, it may maintain the first cutoff switch 81 and the second cutoff switch 82 of the cutoff means 8 in the OFF state, as shown in Fig. 3. Alternatively, in order to prevent the power supply to the high voltage load 30 from being stopped due to the detection of a vehicle-related earth leakage current and at the same time to avoid the risk of electric shock to humans, the control means 7 may maintain the OFF state of the cutoff means 8 for a predetermined time, for example, 0.5 seconds or more, when the earth leakage detection value ILeak of the earth leakage detection means 9 is equal to or greater than a predetermined current value ILth, as shown in Fig. 4, and then repeat the operation of turning the cutoff means 8 on again.

[0059] The configuration of the high-voltage power supply described in this embodiment can be modified as appropriate. For example, the number of storage elements constituting each of the first storage element group 2 and the second storage element group 3 can be modified as appropriate depending on the type of load to be powered. Furthermore, the configuration of the active balancer 4 can be modified as appropriate to match the configurations of the first storage element group 2 and the second storage element group 3. [Industrial Applicability]

[0060] The vehicle power supply device according to the present invention can be mounted on any industrial equipment in addition to vehicles. When applied to equipment other than vehicles, the ground terminal of the leakage detection means 9 must be grounded to a position that provides a reference potential. [Explanation of symbols]

[0061] 1 Vehicle power supply unit 2. First storage element group 3 Second storage element group 4 Active Balancer 5. First Switching Means 6 Secondary Switching Means 7 Control Measures 8. Cut-off means 9. Leak detection means 20 Low voltage load 21 Capacitor 30 High voltage load

Claims

1. 1. A vehicle power supply device that supplies power to a low-voltage load and a high-voltage load that is driven at a voltage higher than that of the low-voltage load, a first storage element group in which a plurality of storage elements are connected in series to obtain a DC power supply of a predetermined voltage; a second group of storage elements, which is configured by connecting a plurality of storage elements in series, and is connected in series to the positive electrode side of the first group of storage elements, and which constitutes a high-voltage DC power supply in combination with the first group of storage elements; an active balancer disposed between the first group of storage elements and the second group of storage elements; a first switch means and a second switch means provided corresponding to an output terminal that supplies a low voltage from the first group of storage elements; a cutoff means for cutting off power from the high voltage DC power supply; a control means for controlling the first switch means and the second switch means to obtain a predetermined low voltage, controlling the active balancer to make the capacities of all the storage elements approximately uniform, and controlling switching of the cutoff means; a leakage current detection means for detecting a leakage current between the high voltage DC power supply and a ground potential and sending a signal to the control means; It is equipped with a control means for determining a signal sent from the leakage current detection means during a dead time period in which the first switch means and the second switch means are in an off state, and for determining if the leakage current reaches a predetermined standard, cutting off power to either or both of the low voltage load and the high voltage load for a predetermined period of time.

2. 2. The vehicle power supply device according to claim 1, wherein the active balancer is connected to three points: a negative electrode side of the first storage element group, a positive electrode side of the second storage element group, and an output terminal provided between the first storage element group and the second storage element group.

3. 2. The power supply device for a vehicle according to claim 1, wherein the control means fixes the interrupting means in an off state when the leakage current reaches a predetermined standard.

4. 2. The vehicle power supply device according to claim 1, wherein the control means, when the leakage current reaches a predetermined standard, keeps the interrupter in an off state for a predetermined time, and then repeats the operation of turning the interrupter on again.

5. 2. The vehicle power supply device according to claim 1, wherein the control means controls the switching means so that the product of the period during which the first switch means and the second switch means are connected to the low voltage load and the leakage detection value of the leakage detection means is 0.003 amperes x 1 second or less.

6. 2. The power supply device for a vehicle according to claim 1, wherein said control means inhibits the connection of said first switch means and said second switch means when said leakage current reaches a predetermined standard.

7. The reference current value of the leakage current is 0 amperes, 2. The vehicle power supply device according to claim 1, wherein the control means cuts off power to either or both of the low voltage load and the high voltage load for a predetermined period of time when the leakage current is greater than 0 amperes.

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