Load driving device and method for controlling load driving device

Abstract

Provided is a load driving device having a plurality of boost circuits connected in parallel, the load driving device being capable of protecting components of the boost circuits and, even if some of the boost circuits fail, continuing a boost operation using other normal boost circuits, thereby providing a highly reliable load driving device. The load driving device includes: a first booster circuit; a second boost circuit connected in parallel with the first boost circuit; a first current interrupting circuit disposed on the upper stage side of the first booster circuit; a second current interrupting circuit disposed on the lower stage side of the first booster circuit; a third current interrupting circuit disposed on the upper stage side of the second booster circuit; a fourth current interrupting circuit disposed on the lower stage side of the second booster circuit; and a calculation device that calculates a control command for controlling the first booster circuit and the second booster circuit, the calculation device cutting off a current from a power supply to the first booster circuit through the first current cutting-off circuit in a case where a failure of the first booster circuit is detected, and cutting off a current from the power supply to the second booster circuit through the second current cutting-off circuit in a case where a failure of the second booster circuit is detected. The current setting value of the second booster circuit is changed to be lower than the current setting value before the failure, and the second booster circuit is operated.

Description

Technical Field

[0001] The present invention relates to a structure of a load driving device for driving and controlling a load and a control method thereof, and in particular to an effective technology suitable for a vehicle-mounted load driving device with high reliability requirements. Background Art

[0002] From the perspective of environmental protection, it is necessary to reduce harmful exhaust gases such as CO, HC, and NOx contained in the exhaust gas of gasoline vehicles, and relevant regulations are becoming more stringent year by year. Against this background, measures are being taken to suppress the penetration of fuel injection, among which multi-stage injection technology that allows a single injection valve to perform continuous injection within a certain period of time is known.

[0003] Since it takes a certain amount of energy to open the fuel injection valve, the battery voltage is usually boosted by a boost circuit. Since multi-stage injection continuously injects fuel within a certain period of time, it is necessary to increase the charging speed through boosting so as to supply energy step by step in a timely manner. As one of the methods to increase the charging speed, it is possible to consider connecting the boost circuit in parallel.

[0004] On the other hand, if any component of the boost circuit connected in parallel fails to the ground (GND), all boost circuits will fail in a chain reaction and stop. The stop of the boost circuit means that the fuel injection valve does not have enough opening energy and cannot inject fuel, which means that the engine will stop, which is very dangerous.

[0005] Therefore, as a fail-safe mechanism for the vehicle, it can be considered that when a failure occurs in any one of the boosting circuits connected in parallel, the circuit that has not failed is operated to continue the boosting operation.

[0006] As background technology in this technical field, there is a technology described in Patent Document 1, for example. Patent Document 1 discloses "a technology in which a current cutoff switch is provided at the upper stage of the power supply side of a boost circuit in which two or more boosting parts are connected in parallel, and when a short-circuit failure occurs in a MOSFET, the failed circuit is electrically separated by the current cutoff switch, so that the boosting operation is continued only by the boost circuit that has not failed." Prior art literature Patent Literature

[0007] Patent document 1: Japanese Patent No. 4848216. Summary of the invention Problem that the invention aims to solve

[0008] However, in the technology of the above-mentioned Patent Document 1, although when a MOSFET of a boost circuit fails, the failed circuit can be electrically separated and the boost operation can be continued using other boost circuits that have not failed, when other components of the boost circuit, i.e., a diode or a capacitor, fail, the failed circuit cannot be electrically separated, so there is a problem that it is difficult to continue the boost operation.

[0009] In addition, it is well known that short-circuit failures other than initial failures of MOSFETs in boost circuits are mostly caused by exceeding the rated power consumption. The boost operation is usually designed in a way to control power consumption, so this failure is mostly suppressed within the design range.

[0010] On the other hand, other components, especially capacitors, are generally electrolytic capacitors, which are relatively weak to heat and current fluctuations during voltage boosting. When used as a component of a voltage boosting circuit, their life is particularly short compared to other components.

[0011] In addition, it is also vulnerable to voltages above the withstand voltage. For example, it is easy to fail when an unexpected voltage above the rated value is applied from a vehicle, etc. It is a component with a high possibility of failure that is difficult for designers to predict. However, in Patent Document 1, it is not subject to electrical separation.

[0012] Therefore, an object of the present invention is to provide a highly reliable load driving device and a control method thereof, wherein in a load driving device having a plurality of boost circuits connected in parallel, it is possible to protect components of the boost circuit while continuing to perform the boost operation using other normal boost circuits even when a part of the boost circuit fails. Technical means of solving problems

[0013] In order to solve the above-mentioned problem, the present invention is characterized in that it comprises: a first boost circuit; a second boost circuit connected in parallel with the first boost circuit; a first current cut-off circuit arranged on the upper side of the first boost circuit; a second current cut-off circuit arranged on the lower side of the first boost circuit; a third current cut-off circuit arranged on the upper side of the second boost circuit; a fourth current cut-off circuit arranged on the lower side of the second boost circuit; and a calculation device, which calculates control instructions for controlling the first boost circuit and the second boost circuit, and when the calculation device detects a fault in the first boost circuit, cuts off the current from the power supply to the first boost circuit through the first current cut-off circuit, and changes the current setting value of the second boost circuit to be lower than that before the fault, thereby operating the second boost circuit.

[0014] In addition, the present invention provides a control method for a load driving device having a plurality of boost circuits connected in parallel, characterized in that it comprises: (a) a step of detecting a fault in a boost circuit; (b) a step of cutting off the current to the faulty boost circuit based on the fault information detected in step (a); and (c) after step (b), a step of changing the current setting value of the boost circuit other than the faulty boost circuit to a value lower than that before the fault, and operating the boost circuits other than the faulty boost circuit. Effects of the Invention

[0015] According to the present invention, a highly reliable load driving device and a control method thereof can be realized. In a load driving device having a plurality of boost circuits connected in parallel, while protecting the components of the boost circuit, even if a part of the boost circuit fails, the boost operation can be continued using other normal boost circuits.

[0016] As a result, for example, in a fuel injection system of an automobile, energy for opening a fuel injection valve can be continuously supplied, thereby preventing the engine from stopping due to a failure of one circuit in the parallel circuit.

[0017] Problems, structures, and effects other than those described above will become clear through the following description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a functional block diagram of the fuel injection valve control device according to the first embodiment of the present invention. Figure 2 Yes means Figure 1 Flow chart of a control method of a fuel injection valve control device. Figure 3 Yes means Figure 1 A timing diagram showing an operation example of a fuel injection valve control device. Figure 4 This is a functional block diagram of a fuel injection valve control device according to a second embodiment of the present invention. Figure 5 Yes means Figure 4 A timing diagram showing an operation example of a fuel injection valve control device. Figure 6 This is a functional block diagram of a fuel injection valve control device according to a third embodiment of the present invention. Figure 7 This is a functional block diagram of a fuel injection valve control device according to a fourth embodiment of the present invention. DETAILED DESCRIPTION

[0019] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In each of the drawings, the same reference numerals are used for the same structures, and detailed descriptions of the duplicated parts are omitted. Example 1

[0020] Reference Figures 1 to 3 , a fuel injection valve control device and a control method thereof according to a first embodiment of the present invention are described.

[0021] Figure 1 1 is a functional block diagram of the fuel injection valve control device 1 of the present embodiment. Figure 2 Yes means Figure 1 Flow chart of a control method of the fuel injection valve control device 1. Figure 3 Yes means Figure 1 1 is a timing chart of an operation example of the fuel injection valve control device 1.

[0022] like Figure 1 As shown, the main structure of the fuel injection valve control device 1 of this embodiment includes: a fuel injection control IC 25, a calculation device 30, a fuel injection circuit 50, and a plurality of booster circuits ( Figure 1 There are two boost circuits 100 and 200).

[0023] The fuel injection control IC 25 includes a voltage monitor 20 , a current monitor 105 , a boost controller 106 , a current monitor 205 , and a boost controller 206 .

[0024] The calculation device 30 includes a boost setting controller 35 having a current table selector 40 and a current table 45 , and a current cutoff controller 300 .

[0025] The boost circuit 100 includes a boost coil 101, a boost driver (FET) 102, a boost diode 103, and a boost capacitor 104. An upstream current cutoff circuit 110 is disposed on the upper side of the boost circuit 100, and a downstream current cutoff circuit 111 is disposed on the lower side.

[0026] The boost circuit 200 includes a boost coil 201, a boost driver (FET) 202, a boost diode 203, and a boost capacitor 204. An upstream current cutoff circuit 210 is disposed on the upper side of the boost circuit 200, and a downstream current cutoff circuit 211 is disposed on the lower side.

[0027] The fuel injection valve control device 1 is connected to the fuel injection valve 2 as a load, and controls the driving of the fuel injection valve 2 .

[0028] In addition, in this embodiment, the boost circuit adopts a dual parallel structure, but depending on the application, it is also possible to imagine a situation where the number of boost circuits connected in parallel is more than three. Even in this case, its basic structure is also assumed to be a structure equivalent to one boost circuit described later in parallel with the same structure.

[0029] When the upper and lower limit current setting values ​​of the boost control are set to the fuel injection control IC 25 from the boost setting controller 35 in the calculation device 30, the boost controller 106 and the boost controller 206 measure the boost voltage using the voltage monitor 20 for measuring the boost voltage, and start the boost operation when the boost voltage is below the specified voltage.

[0030] During the boost process, the current monitor 105 and the current monitor 205 measure the circuit currents flowing through the boost circuit 100 and the boost circuit 200, and the boost controller 106 and the boost controller 206 perform duty cycle control on each boost driver 102 and the boost driver 202 so that the measured current values ​​in the current monitor 105 and the current monitor 205 are the same as the upper and lower current limit setting values ​​mentioned above.

[0031] On the power supply side of the booster coils 101 and 201 in the booster circuits 100 and 200, there are upstream current cutoff circuits 110 and 210 for cutting off the circuit current, and on the cathode side of the booster diodes 103 and 203, that is, on the voltage output sides of the booster circuits 100 and 200, there are downstream current cutoff circuits 111 and 211 which are the same as the upstream current cutoff circuits 110 and 210. With this structure, when an abnormality occurs in the booster circuits 100 and 200, the current flowing through the circuits can be cut off by the upstream current cutoff circuits 110, 210 and the downstream current cutoff circuits 111, 211 according to the instruction from the current cutoff controller 300 in the calculation device 30.

[0032] In this embodiment, the upstream section current cut-off circuit 110 and the downstream section current cut-off circuit 111, and the upstream section current cut-off circuit 210 and the downstream section current cut-off circuit 211 are paired respectively, and form a structure capable of cutting off the current according to instructions from the current cut-off controller 300 in the computing device 30.

[0033] For example, when an abnormality occurs in the boost circuit 100, the upstream current cutoff circuit 110 and the downstream current cutoff circuit 111 can cut off the current at the same time according to the instruction from the current cutoff controller 300 in the calculation device 30. On the other hand, when an abnormality occurs in the boost circuit 200, the upstream current cutoff circuit 210 and the downstream current cutoff circuit 211 can cut off the current at the same time according to the instruction from the current cutoff controller 300 in the calculation device 30.

[0034] In the present embodiment, in each of the booster circuits 100 and 200, the current cutoff circuit is configured to form a pair of upstream and downstream stages. However, a configuration in which all current cutoff circuits are controlled independently of each other will be described later in the second embodiment.

[0035] The voltage monitor 20 measures the boosted voltage accumulated by the boost operation, and when the boosted voltage reaches a predetermined voltage, the boost controller 106 and the boost controller 206 stop the boost operation.

[0036] The upper and lower limit current setting values ​​set for the fuel injection control IC 25 by the boost setting controller 35 in the calculation device 30 are selected from the current table 45 by the current table selector 40 .

[0037] In addition to the above-mentioned boosting operation, the fuel injection control IC 25 receives a fuel injection command generated by the calculation device 30 based on the engine speed signal and outputs a fuel injection control signal to the fuel injection circuit 50 , thereby driving the fuel injection valve 2 to perform fuel injection.

[0038] The valve opening energy of the fuel injection valve 2 uses the boosted voltage generated by the booster circuit 100 and the booster circuit 200 and the power supply voltage.

[0039] Next, we also use Figure 2 Flowchart and Figure 3 An operation example of the fuel injection valve control device 1 will be described with reference to the timing chart of FIG.

[0040] When the control of the voltage step-up operation is started (step S1 ), first, the current table selector 40 selects table A from table A and table B, which are upper and lower limit current setting values ​​for the voltage step-up control current, in the current table 45 (step S2 ).

[0041] like Figure 3 As shown, the relationship between the boost average currents in the two upper and lower limit current setting value tables A and B is "Table B < Table A". Table A is the upper and lower limit current setting values ​​suitable for the case where all boost circuits connected in parallel are normal, and Table B is the upper and lower limit current setting values ​​suitable for the case where one boost circuit fails.

[0042] In addition, in the present embodiment, since the boost circuit is connected in parallel with two circuits, there are two current tables 45. However, when the number of boost circuits connected in parallel is three or more, tables equal to the number of boost circuits connected in parallel are prepared, and the relationship between the upper and lower current setting values ​​and the boost average current is as follows: Table A is the upper and lower current setting values ​​suitable for the case where all boost circuits are normal, and from the second table onwards, the upper and lower current setting values ​​are set to be suitable for the respective number of faults as the number of boost circuits that have faults increases.

[0043] In addition, the relationship between the boost average currents of the various tables is set such that the more suitable the table is for the case where the number of fault circuits is large, the lower the boost average current is. For example, in the case where three boost circuits are connected in parallel, three tables A, B, and C are prepared, and the relationship between the boost average currents is "Table C < Table B < Table A".

[0044] Table A shows the upper and lower current limit setting values ​​suitable for the case where all boost circuits connected in parallel are normal, Table B shows the upper and lower current limit setting values ​​suitable for the case where one boost circuit fails, and Table C shows the upper and lower current limit setting values ​​suitable for the case where two boost circuits fail.

[0045] The boost setting controller 35 , which has selected the table A of upper and lower limit current setting values ​​by the current table selector 40 , issues an instruction for setting the upper and lower limit currents to the fuel injection control IC 25 .

[0046] Next, the fuel injection control IC 25 which has received the instruction from the boost setting controller 35 starts boost control using the boost circuit 100 and the boost circuit 200 (step S3 ).

[0047] In the boost control, the current cutoff controller 300 performs ON / OFF control of the upstream-stage current cutoff circuits 110 and 210 and the downstream-stage current cutoff circuits 111 and 211 based on the circuit failure information of the boost circuit.

[0048] The calculation device 30 determines whether or not there is a failure in the booster circuit 100 based on the input circuit failure information (step S4 ).

[0049] Based on the fault information of the boost circuit 100, when it is detected that the boost circuit 100 has a fault (yes), the boosting of the boost circuit 100 and the boost circuit 200 is stopped (step S5), and the current I flowing from the power supply to the boost circuit 100 is cut off by turning off the upstream current cut-off circuit 110 and the downstream current cut-off circuit 111 (step S6).

[0050] Then, the calculation device 30 determines whether or not there is a failure in the booster circuit 200 based on the input circuit failure information (step S7 ).

[0051] Based on the fault information of the boost circuit 200, when it is detected that a fault has occurred in the boost circuit 200 (yes), the current I flowing from the power supply to the boost circuit 200 is cut off by turning off the upstream current cut-off circuit 210 and the downstream current cut-off circuit 211 (step S8), and the boost control is ended (step S13).

[0052] In step S7, when it is detected that the boost circuit 200 has not failed (is functioning normally) (No), the table B of the upper and lower current setting values ​​is selected by the current table selector 40 (step S12), and an instruction for setting the upper and lower current limits is issued to the fuel injection control IC25, and the fuel injection control IC25 starts the boosting action performed by the boost circuit 200.

[0053] On the other hand, in step S4 , when it is detected that the booster circuit 100 is not faulty (functioning normally) (No), the presence or absence of a fault in the booster circuit 200 is determined based on the input circuit fault information (step S9 ).

[0054] According to the fault information of the boost circuit 200, when it is detected that the boost circuit 200 has a fault (yes), the boosting of the boost circuit 200 and the boost circuit 100 is stopped (step S10), and the current flowing from the power supply to the boost circuit 200 is cut off by turning OFF the upstream current cut-off circuit 210 and the downstream current cut-off circuit 211 (step S11). Thereafter, the table B of the upper and lower limit current setting values ​​is selected by the current table selector 40 (step S12), and an upper and lower limit current setting instruction is issued to the fuel injection control IC25, and the fuel injection control IC25 starts the boosting action performed by the boost circuit 100.

[0055] In addition, in step S9, when it is detected that the boost circuit 200 has not failed (functions normally) (No), since neither the boost circuit 100 nor the boost circuit 200 has a boost circuit failure, the boost control is continued in the state where the upper and lower limit current setting values ​​are in Table A (step S3).

[0056] In addition, Figure 2In the flowchart of FIG. 1 , the process is first performed based on the fault information of the booster circuit 100, but it is also assumed that the process is performed based on the fault information of the booster circuit 200, or the fault information of the booster circuit 100 and the booster circuit 200 are processed simultaneously. In addition, the fault information of the booster circuit input to the calculation device 30 is assumed to be information obtained from the fuel injection control IC 25, information determined by the calculation device 30 itself, and information obtained by a fault determination circuit not shown in the figure.

[0057] According to the present embodiment, the failed boost circuit is electrically isolated by cutting off the current flowing from the power supply to the failed boost circuit, and by changing the upper and lower current limit setting values ​​to be suitable for the remaining boost circuits, the other boost circuits that have not failed can continue the boost operation without suffering thermal damage due to boost loss.

[0058] Thus, energy for opening the fuel injection valve can be continuously supplied, and the engine can be prevented from stopping due to a failure in one of the parallel circuits.

[0059] In addition, by cutting off the current that continues to flow from the power supply to the faulty circuit, it is also possible to prevent secondary faults such as thermal burnout of the substrate caused by further heating of the faulty circuit portion due to the power supply current continuing to flow to the faulty circuit portion, insulation breakdown of the capacitor included in the boost circuit, and destruction of the power supply circuit that serves as the current supply source to the boost circuit. Example 2

[0060] Reference Figure 4 as well as Figure 5 , a fuel injection valve control device and a control method thereof according to a second embodiment of the present invention are described.

[0061] Figure 4 1 is a functional block diagram of the fuel injection valve control device 1 of the present embodiment. Figure 5 Yes means Figure 4 Flow chart of a control method of the fuel injection valve control device 1.

[0062] In Example 1 ( Figure 1 ) is a structure in which the upstream current cutoff circuit and the downstream current cutoff circuit of each boost circuit are simultaneously controlled to be ON or OFF by the current cutoff controller 300 for each boost circuit. However, in this embodiment ( Figure 4 ) is a structure in which the ON and OFF controls of the upstream current cutoff circuit and the downstream current cutoff circuit can be controlled independently in each cutoff circuit.

[0063] The basic components of a boost circuit include a boost coil, a boost driver (FET), a boost diode, and a boost capacitor. However, if a short-circuit failure occurs between each component and GND, the power supply current will flow to the failed circuit, and thus the boosting of all the boost circuits connected in parallel cannot continue. If an open-circuit failure occurs in the above components, the power supply current will not flow to the failed circuit, and thus no secondary failure will occur.

[0064] If all the components of the booster circuit are normal, the voltage can be continuously boosted without cutting off the current, and if the booster capacitor is not faulty, it can serve as a rechargeable battery for the booster circuit that is not faulty.

[0065] The above also applies to a short-circuit failure of the boost driver (FET). In the event of a short-circuit failure of the boost driver (FET), if the current flowing to the short-circuited boost driver (FET) can be cut off, the boost capacitor can continue to be used as a rechargeable battery if the boost capacitor has not failed.

[0066] In Example 1 ( Figure 1 ) is a structure in which ON and OFF control of the upstream current cutoff circuit and the downstream current cutoff circuit of each boost circuit is simultaneously performed, and the current cutoff circuit is turned OFF according to the fault judgment, thereby electrically separating the faulty boost circuit as a whole from the normal boost circuit. Therefore, even if the boost capacitor of the faulty boost circuit can continue to be used, it cannot continue to be used as a rechargeable battery.

[0067] Therefore, in the present embodiment, by forming a structure in which the current cutoff circuits of the upstream section and the downstream section are controlled independently of each other, when the boost driver (FET) has a short-circuit fault, only the current cutoff circuit of the upstream section can be turned OFF to cut off the current flowing to the boost driver (FET) having the short-circuit fault. In addition, with respect to the current flowing back from the boost circuit that has not failed to flow into the boost driver (FET) having the short-circuit fault, the backflow of the current is prevented by the backflow prevention boost diode provided as the basic structure of the boost circuit, thereby making it possible to electrically separate the short-circuited boost driver (FET).

[0068] use Figure 5 The operation example of the fuel injection valve control device 1 of this embodiment is described with reference to the flowchart.

[0069] When the control of the boost operation starts (step S1), first, the current table selector 40 selects table A from table A and table B as the upper and lower limit current setting value tables for the boost control current in the current table 45 (step S2). The contents of the two upper and lower limit current setting value tables A and B are the same as those in the first embodiment.

[0070] Next, the fuel injection control IC 25 which has received the instruction from the boost setting controller 35 starts boost control using the boost circuit 100 and the boost circuit 200 (step S3 ).

[0071] Next, the calculation device 30 determines whether or not there is a failure in the booster circuit 100 based on the input circuit failure information (step S4 ).

[0072] When it is detected based on the failure information of the booster circuit 100 that the booster circuit 100 has failed (Yes), the boosting of the booster circuit 100 and the booster circuit 200 is stopped (step S5).

[0073] Next, the calculation device 30 determines whether the fault that is occurring is only a short-circuit fault of the boost driver (FET) 102 based on the input circuit fault information (step S6 ).

[0074] When it is detected that the fault occurring is only the short-circuit fault of the boost driver (FET) 102 (Yes), the upstream current cutoff circuit 110 is turned OFF (step S7) to prevent the current I from flowing from the power supply to GND via the failed boost driver (FET) 102.

[0075] Next, the calculation device 30 determines whether or not there is a failure in the booster circuit 200 based on the input circuit failure information (step S8 ).

[0076] Based on the fault information of the boost circuit 200, when it is detected that a fault has occurred in the boost circuit 200 (yes), the current I flowing from the power supply to the boost circuit 200 is cut off by turning OFF the upstream current cut-off circuit 210 and the downstream current cut-off circuit 211 (step S9), and the boost control is ended (step S18).

[0077] On the other hand, in step S4 , when it is detected that the booster circuit 100 is not faulty (functioning normally) (No), the presence or absence of a fault in the booster circuit 200 is determined based on the input circuit fault information (step S10 ).

[0078] When it is detected based on the failure information of the booster circuit 200 that the booster circuit 200 has failed (Yes), the boosting of the booster circuit 200 and the booster circuit 100 is stopped (step S11 ).

[0079] Next, the calculation device 30 determines whether the fault that is occurring is only a short-circuit fault of the boost driver (FET) 202 based on the input circuit fault information (step S12).

[0080] When it is detected that the fault occurring is only a short-circuit fault of the boost driver (FET) 202 (Yes), the upstream current cutoff circuit 210 is turned OFF (step S13) to prevent the current I from flowing from the power supply to GND via the failed boost driver (FET) 202.

[0081] Then, the table B of the upper and lower limit current setting values ​​is selected by the current table selector 40 (step S14 ), and an upper and lower limit current setting instruction is issued to the fuel injection control IC 25 , and the fuel injection control IC 25 continues the voltage boosting operation by the voltage boosting circuit 100 .

[0082] In step S12, when it is detected that the occurring fault is not a short-circuit fault of the boost driver (FET) 202 (No), the computing device 30 determines whether the occurring fault is only an open-circuit fault of the boost driver (FET) 202 based on the input circuit fault information (step S16).

[0083] When it is detected that the occurring fault is only the open-circuit fault of the boost driver (FET) 202 (Yes), components of the boost circuit 200 other than the boost driver (FET) 202 can continue to be used, and the boost operation by the boost circuit 100 continues.

[0084] On the other hand, when it is detected that the occurring fault is not an open circuit fault of the boost driver (FET) 202 (No), the boost circuit 200 is electrically separated by turning OFF the upstream current cut-off circuit 210 and the downstream current cut-off circuit 211 (step S17), and the boost operation performed by the boost circuit 100 continues.

[0085] In step S6, when it is detected that the occurring fault is not a short-circuit fault of the boost driver (FET) 102 (No), the computing device 30 determines whether the occurring fault is only an open-circuit fault of the boost driver (FET) 102 based on the input circuit fault information (step S15).

[0086] When it is detected that the occurring fault is only the open-circuit fault of the boost driver (FET) 102 (Yes), components of the boost circuit 100 other than the boost driver (FET) 102 can continue to be used, and the boost operation by the boost circuit 200 continues.

[0087] On the other hand, when it is detected that the occurring fault is not an open circuit fault of the boost driver (FET) 102 (No), the boost circuit 100 is electrically separated by turning OFF the upstream current cut-off circuit 110 and the downstream current cut-off circuit 111 (step S19), and the boost operation performed by the boost circuit 200 continues.

[0088] In the present embodiment, the current cutoff circuits are configured to be controlled independently of each other, so that when the boosting capacitor can continue to be used, the boosting capacitor can continue to be used as a rechargeable battery.

[0089] Furthermore, even when the open circuit failure occurs in any of the boost coil, boost driver (FET), or boost diode, the same effect as that of the boost driver (FET) failure can be obtained by prohibiting the current cutoff circuit from turning OFF.

[0090] However, in the event that any component fails, in order to prevent the remaining boost circuits from being damaged by heat and thus continuing to boost, it is necessary to switch to upper and lower current limit setting values ​​that are suitable for the remaining number of boost circuits. Therefore, as in Example 1, boost stop is implemented, and the table of upper and lower current limit setting values ​​is selected as the optimal table corresponding to the remaining number of circuits. Thereafter, the current cut-off circuit is kept ON and energized, thereby restarting boost. Example 3

[0091] Reference Figure 6 A fuel injection valve control device and a control method thereof according to a third embodiment of the present invention will be described. Figure 6 1 is a functional block diagram of the fuel injection valve control device 1 of the present embodiment.

[0092] like Figure 6 As shown, the fuel injection valve control device 1 of this embodiment is different from that of embodiment 1 ( Figure 1 ) and Example 2 ( Figure 4 ) is different in that: alternative embodiment 1 ( Figure 1 ) and Example 2 ( Figure 4 ) downstream current cut-off circuits 111 and 211, and downstream current reverse flow prevention diodes 112 and 212 are respectively configured on the voltage output sides of the boost circuit 100 and the boost circuit 200. Other structures are similar to those of the embodiment 1 ( Figure 1 ) and Example 2 ( Figure 4 )same.

[0093] The circuit structure is as follows: the downstream current cutoff circuit 111 is changed into a downstream current backflow prevention diode 112 , and the downstream current cutoff circuit 211 is changed into a downstream current backflow prevention diode 212 .

[0094] When a short-circuit failure occurs in the boost capacitor 104 and the boost capacitor 204, in order to electrically isolate the failed boost circuit, in addition to cutting off the current inflow from the power supply, it is also necessary to cut off the current reverse flow from the output side of other parallel circuits. Therefore, by connecting the anode side of the downstream current reverse flow prevention diodes 112 and 212 to the output side of the boost circuit and configuring the cathode side as the voltage output side, the current reverse flow from the output side of other parallel circuits can be cut off.

[0095] This embodiment changes the downstream current cutoff circuit into a downstream current backflow prevention diode, thereby eliminating the need to control the ON and OFF of the downstream current cutoff circuit, thereby reducing the circuit driving load for the calculation device 30 to drive the downstream current cutoff circuit. Example 4

[0096] Reference Figure 7 A fuel injection valve control device and a control method thereof according to a fourth embodiment of the present invention will be described. Figure 7 1 is a functional block diagram of the fuel injection valve control device 1 of the present embodiment.

[0097] like Figure 7 As shown, the fuel injection valve control device 1 of this embodiment is different from that of embodiment 1 ( Figure 1 ) and Example 2 ( Figure 4 ) is different in that: alternative embodiment 1 ( Figure 1 ) and Example 2 ( Figure 4 ) upstream current cut-off circuit 110, 210 and downstream current cut-off circuit 111, 211, and respectively configure independent current cut-off mechanism 113, 114, 213, 214. Other structures are similar to those of embodiment 1 ( Figure 1 ) and Example 2 ( Figure 4 )same.

[0098] The circuit is structured such that the upstream current cutoff circuit and the downstream current cutoff circuit are replaced with an element such as a fuse that autonomously cuts off the current when a current exceeding a certain value flows.

[0099] This embodiment changes the upstream current cutoff circuit and the downstream current cutoff circuit into elements that autonomously cut off the current when a current exceeding a certain level flows through the circuit, thereby enabling the faulty circuit to be electrically isolated immediately when an overcurrent beyond expectations flows through the circuit.

[0100] This can further reduce the risk of secondary failures such as thermal damage to the substrate caused by continued flow of power supply current to the faulty circuit, further heating of the faulty circuit portion, and destruction of the power supply circuit serving as the current supply source to the boost circuit.

[0101] In addition, since it is not necessary to control the ON and OFF of the current cutoff circuit by the calculation device 30, the circuit driving load required for the calculation device 30 to cut off the current can be reduced.

[0102] In addition, in the above-mentioned embodiments, a fuel injection valve control device that drives and controls a fuel injection valve is described as an example of a load driving device, but the parallel boost circuit can be used for driving a high-output motor of an automotive device, etc., a load driving device that requires a high-voltage boost, a load driving device that emphasizes charging speed, etc., as a device for reducing the circuit burden caused by heat loss in each circuit. A wide range of uses can be envisioned, and the present invention can also be applied to all of the above-mentioned load driving devices.

[0103] In addition, the present invention is not limited to the above-mentioned embodiments, but includes various modified examples. For example, the above-mentioned embodiments are embodiments that are described in detail in order to easily explain the present invention, but are not limited to embodiments having all the structures described. In addition, a part of the structure of a certain embodiment can be replaced with the structure of another embodiment, and the structure of another embodiment can be added to the structure of a certain embodiment. In addition, for a part of the structure of each embodiment, other structures can be added, deleted, or replaced. Explanation of symbols

[0104] 1… fuel injection valve control device (load driving device), 2… fuel injection valve (load), 20… voltage monitor, 25… fuel injection control IC, 30… calculation device, 35… boost setting controller, 40… current table selector, 45… current table, 50… fuel injection circuit, 100, 200… boost circuit, 101, 201… boost coil, 102, 202… boost driver (FET), 103, 203… boost diode, 104, 204… boost capacitor, 105, 205… current monitor, 106, 206… boost controller, 110, 210… upstream current cutoff circuit, 111, 211… downstream current cutoff circuit, 112, 212… downstream current reverse flow prevention diode, 113, 114, 213, 214… autonomous current cutoff mechanism, 300… current cutoff controller.

Claims

1. A load driving device, characterized in that: have: A first boost circuit; a second boost circuit connected in parallel with the first boost circuit; a first current cutoff circuit disposed on an upper stage side of the first boost circuit; a second current cutoff circuit disposed on the lower stage side of the first boost circuit; a third current cutoff circuit disposed on an upper stage side of the second boost circuit; a fourth current cutoff circuit disposed on the lower side of the second boost circuit; as well as a calculation device for calculating a control instruction for controlling the first boost circuit and the second boost circuit, When the calculation device detects a failure of the first boost circuit, the first current cutoff circuit cuts off the current from the power supply to the first boost circuit, and changes the current setting value of the second boost circuit to be lower than that before the failure, thereby operating the second boost circuit.

2. The load driving device according to claim 1, characterized in that: When the computing device detects a fault in the first boost circuit and detects that the detected fault is a short-circuit fault of a component constituting the first boost circuit, the current from the power supply to the first boost circuit is cut off by the first current cutoff circuit, and the current from the second boost circuit to the first boost circuit is cut off by the second current cutoff circuit.

3. The load driving device according to claim 1, characterized in that: The second current cutoff circuit and the fourth current cutoff circuit are diodes arranged such that the anode side is connected to the output side of the first boosting circuit and the second boosting circuit and the cathode side serves as a voltage output side.

4. The load driving device according to claim 1, characterized in that: The first current cutoff circuit, the second current cutoff circuit, the third current cutoff circuit, and the fourth current cutoff circuit are elements that autonomously cut off current when a current exceeding a certain value flows.

5. The load driving device according to claim 1, characterized in that: Before the current setting value of the second boost circuit is changed to a lower value, the boosting operations of the first boost circuit and the second boost circuit are stopped.

6. The load driving device according to claim 1, characterized in that: When the computing device detects a fault in the first boost circuit and detects that the detected fault is an open circuit fault of a component constituting the first boost circuit, the current is not cut off by the first current cutoff circuit, the second current cutoff circuit, the third current cutoff circuit, and the fourth current cutoff circuit.

7. The load driving device according to claim 1, characterized in that: The first current cutoff circuit, the second current cutoff circuit, the third current cutoff circuit, and the fourth current cutoff circuit can be controlled independently of each other.

8. The load driving device according to claim 1, characterized in that: When the computing device detects a fault in the first boost circuit and detects that the detected fault is a short-circuit fault of a boost driver constituting the first boost circuit, only the first current cutoff circuit is actuated to cut off the current from the power supply to the first boost circuit.

9. A control method for a load driving device having a plurality of boost circuits connected in parallel, characterized in that: have: (a) a step of detecting a fault in a boost circuit; (b) a step of cutting off the current to the faulty booster circuit based on the fault information detected in step (a); as well as (c) After the step (b), the step of changing the current setting value of the booster circuit other than the failed booster circuit to be lower than that before the failure, and operating the booster circuit other than the failed booster circuit.

10. The control method of the load driving device according to claim 9, characterized in that: When the fault detected in step (a) is a short-circuit fault of a component constituting the boost circuit, the current from the power supply to the faulty boost circuit is cut off, and the current from boost circuits other than the faulty boost circuit to the faulty boost circuit is cut off.

11. The control method of the load driving device according to claim 9, characterized in that: Before the step (c), the voltage boosting operations of the plurality of voltage boosting circuits are stopped.

12. The control method of the load driving device according to claim 9, characterized in that: When the failure detected in the step (a) is an open circuit failure of a component constituting the boost circuit, the current is not cut off in the step (b).

13. The control method of the load driving device according to claim 9, characterized in that: When the fault detected in step (a) is a short-circuit fault of a boost driver constituting a boost circuit, only the current from the power supply to the faulty boost circuit is cut off.

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