Load drive device, control method for load drive device

Abstract

Provided is a load driving device having a plurality of boost circuits connected in parallel and achieving such a high reliability that, while protecting the components of the boost circuits, even when some of the boost circuits have failed, a boost operation can be continued by the other normal boost circuits. The load driving device is characterized by comprising: a first boost circuit; a second boost circuit connected to the first boost circuit in parallel; a first current cutoff circuit disposed on the 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 the upper stage side of the second boost circuit; a fourth current cutoff circuit disposed on the lower stage side of the second boost circuit; and a calculation device that calculates control commands for controlling the first boost circuit and the second boost circuit. The calculation device cuts off the current from a power supply to the first boost circuit by the first current cutoff circuit when detecting a failure of the first boost circuit and changes the current setting value of the second boost circuit to a value lower than that before the failure to operate the second boost circuit.

Description

Technical Field

[0001] The present invention relates to a configuration of a load driving device for driving and controlling a load and a control method thereof, and particularly relates to a technique effective when applied to an in-vehicle load driving device that requires high reliability.

Background Art

[0002] From the viewpoint of environmental protection, reduction of harmful exhaust gases such as CO, HC, and NOx contained in the exhaust gas of gasoline vehicles is required, and the regulations have become stricter year by year. Among them, measures for suppressing the penetration of fuel injection have been taken, and among others, a multi-stage injection technique in which a single injection valve continuously injects fuel within a certain period of time is known.

[0003] Since a certain amount of energy is required to open the fuel injection valve, a method of boosting the battery voltage with a booster circuit is common. However, since multi-stage injection continuously performs fuel injection within a certain period of time, it is necessary to increase the charging speed by boosting so that energy can be supplied in time for each stage. As one method of increasing the charging speed, parallelization of the booster circuit is considered.

[0004] On the other hand, if any component of the parallel-connected booster circuit shorts to GND, there is a problem that all the booster circuits will fail and stop together. The stop of the booster circuit means that the opening energy of the fuel injection valve becomes insufficient and fuel injection cannot be performed, that is, it leads to the engine stopping, which is dangerous.

[0005] Therefore, as a fail-safe mechanism of the vehicle, it is conceivable to continue the boosting operation by operating the non-failed circuit when any of the parallelized booster circuits fails.

[0006] As background technology for this field, for example, there is technology such as that described in Patent Document 1. Patent Document 1 discloses "a technology in which a current interruption switch is provided on the upper stage of the power supply side of a boost circuit in which two or more boost units are arranged in parallel, and in the event of a short-circuit failure of a MOSFET, the current interruption switch electrically isolates the faulty circuit, thereby allowing the boost operation to continue with only the boost circuit that is not faulty." [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 4848216 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] By the way, in the technology described in Patent Document 1, when a MOSFET in the boost circuit fails, it is possible to electrically isolate the faulty circuit and continue the boost operation with the other, non-faulty boost circuit. However, when other components of the boost circuit, such as diodes or capacitors, fail, it is not possible to electrically isolate the faulty circuit, which presents a problem in that it becomes difficult to continue the boost operation.

[0009] Furthermore, it is known that most short-circuit failures in boost circuits, excluding initial MOSFET failures, are due to exceeding the power consumption rating. Since boost operation is usually designed to control power consumption, most of these failures are suppressed within the design limits.

[0010] On the other hand, other components, especially capacitors, are generally electrolytic capacitors, which are susceptible to heat and current fluctuations during voltage boosting. When used as components in a voltage boosting circuit, they tend to have a particularly short lifespan compared to other components.

[0011] Furthermore, it is vulnerable to voltages exceeding its withstand voltage, and if, for example, a voltage exceeding its rating is applied unintentionally from a vehicle, it will easily fail. Although it is a component that is highly likely to fail unintentionally by the designer, it is not subject to electrical isolation in Patent Document 1.

[0012] Therefore, the object of the present invention is to provide a highly reliable load drive device and a control method thereof, which have a plurality of boost circuits connected in parallel, that can protect the components of the boost circuits and continue boost operation with other normal boost circuits even if some of the boost circuits fail. [Means for solving the problem]

[0013] To solve the above problems, the present invention provides a first boost circuit, a second boost circuit connected in parallel to the first boost circuit, a first current interruption circuit located on the upper side of the first boost circuit, a second current interruption circuit located on the lower side of the first boost circuit, a third current interruption circuit located on the upper side of the second boost circuit, a fourth current interruption circuit located on the lower side of the second boost circuit, and a computing device that calculates control commands for controlling the first boost circuit and the second boost circuit, wherein the computing device, when it detects a failure in the first boost circuit, interrupts the current from the power supply to the first boost circuit using the first current interruption circuit, changes the current setting value of the second boost circuit to a lower value than before the failure, and operates the second boost circuit.

[0014] Furthermore, the present invention relates to a control method for a load drive device having a plurality of boost circuits connected in parallel, comprising: (a) a step of detecting a failure in a boost circuit; (b) a step of interrupting the current to the failed boost circuit based on the failure information detected in step (a); and (c) a step of operating the boost circuits other than the failed boost circuit after step (b) by changing the current setting value of the boost circuits other than the failed boost circuit to a lower value than before the failure. [Effects of the Invention]

[0015] According to the present invention, in a load driving device having a plurality of boost circuits connected in parallel, while protecting the components of the boost circuit, even when a part of the boost circuit fails, a highly reliable load driving device capable of continuing the boosting operation with other normal boost circuits and its control method can be realized.

[0016] As a result, for example, in an automobile fuel injection system, it becomes possible to continue supplying energy for opening the fuel injection valve, and it is possible to prevent engine stop caused by the failure of one circuit in the parallel circuit.

[0017] Problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0018] [Figure 1] It is a functional block diagram of a fuel injection valve control device according to Embodiment 1 of the present invention. [Figure 2] It is a flowchart showing a control method of the fuel injection valve control device of FIG. 1. [Figure 3] It is a timing chart showing an operation example of the fuel injection valve control device of FIG. 1. [Figure 4] It is a functional block diagram of a fuel injection valve control device according to Embodiment 2 of the present invention. [Figure 5] It is a timing chart showing an operation example of the fuel injection valve control device of FIG. 4. [Figure 6] It is a functional block diagram of a fuel injection valve control device according to Embodiment 3 of the present invention. [Figure 7] It is a functional block diagram of a fuel injection valve control device according to Embodiment 4 of the present invention.

Modes for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and detailed descriptions of overlapping parts will be omitted.

Embodiment

[0020] Referring to FIGS. 1 to 3, a fuel injection valve control device and its control method according to Embodiment 1 of the present invention will be described.

[0021] FIG. 1 is a functional block diagram of the fuel injection valve control device 1 of this embodiment. FIG. 2 is a flowchart showing the control method of the fuel injection valve control device 1 in FIG. 1. FIG. 3 is a timing chart showing an operation example of the fuel injection valve control device 1 in FIG. 1.

[0022] As shown in FIG. 1, the fuel injection valve control device 1 of this embodiment mainly includes a fuel injection control IC 25, an arithmetic unit 30, a fuel injection circuit 50, and a plurality of boost circuits (two boost circuits 100 and 200 in FIG. 1) connected in parallel between the fuel injection control IC 25 and the fuel injection circuit 50.

[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 arithmetic unit 30 includes a current table selection unit 40 and a boost setting controller 35 having a current table 40, and a current cut-off controller 300.

[0025] The boost circuit 100 is composed of a boost coil 101, a boost driver (FET) 102, a boost diode 103, and a boost capacitor 104. An upstream stage current cut-off circuit 110 is arranged on the upper stage side of the boost circuit 100, and a downstream stage current cut-off circuit 111 is arranged on the lower stage side.

[0026] The boost circuit 200 is composed of a boost coil 201, a boost driver (FET) 202, a boost diode 203, and a boost capacitor 204. An upstream stage current cut-off circuit 210 is arranged on the upper stage side of the boost circuit 200, and a downstream stage current cut-off circuit 211 is arranged on the lower stage side.

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

[0028] In this embodiment, the boost circuit is configured as two in parallel, but depending on the application, it is conceivable that the boost circuit may be configured as three or more in parallel. In that case as well, the basic configuration is expected to be the same as that of one boost circuit, as described later, but arranged in parallel.

[0029] When the boost setting controller 35 in the calculation unit 30 sets the upper and lower limit current setting values ​​for boost control to the fuel injection control IC 25, the boost controllers 106 and 206 measure the boosted voltage with the voltage monitor 20, and if the boosted voltage is below a predetermined voltage, they start the boost operation.

[0030] During voltage boosting, current monitors 105 and 205 measure the respective circuit currents flowing through boost circuit 100 and boost circuit 200, and boost controllers 106 and 206 perform duty cycle control of boost drivers 102 and 202 so that the measured current values ​​from current monitors 105 and 205 are the same as the upper and lower limit current settings mentioned above.

[0031] The boost circuits 100 and 200 are equipped with upstream current interruption circuits 110 and 210 on the power supply side of the boost coils 101 and 201, respectively, to interrupt the circuit current. Furthermore, the cathode side of the boost diodes 103 and 203, i.e., the voltage output side of the boost circuits 100 and 200, are also equipped with downstream current interruption circuits 111 and 211, similar to the upstream current interruption circuits 110 and 210. With this configuration, in the event of a malfunction in the boost circuit 100 or 200, the current flowing through the circuit can be interrupted by the upstream current interruption circuits 110 and 210 and the downstream current interruption circuits 111 and 211, based on a command from the current interruption controller 300 in the computing unit 30.

[0032] In this embodiment, the upstream current interruption circuit 110 and the downstream current interruption circuit 111, and the upstream current interruption circuit 210 and the downstream current interruption circuit 211 are paired together, and the current can be interrupted by a command from the current interruption controller 300 in the computing unit 30.

[0033] For example, if an abnormality occurs in the boost circuit 100, the current can be simultaneously cut off by the upstream current cutoff circuit 110 and the downstream current cutoff circuit 111 based on a command from the current cutoff controller 300 in the arithmetic unit 30. On the other hand, if an abnormality occurs in the boost circuit 200, the current can be simultaneously cut off by the upstream current cutoff circuit 210 and the downstream current cutoff circuit 211 based on a command from the current cutoff controller 300 in the arithmetic unit 30.

[0034] In this embodiment, the current interruption circuits in each of the boost circuits 100 and 200 are configured as a pair of upstream and downstream stages. However, a configuration in which all current interruption circuits are controlled independently of each other will be described later in Embodiment 2.

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

[0036] The upper and lower limit current setting values ​​set by the boost setting controller 35 in the calculation unit 30 to the fuel injection control IC 25 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 IC25 receives a fuel injection command generated by the calculation unit 30 based on the engine rotation signal and outputs a fuel injection control signal to the fuel injection circuit 50, which then drives the fuel injection valve 2 to perform fuel injection.

[0038] The opening energy for the fuel injection valve 2 is obtained from the boosted voltage generated by the boost circuit 100 and the boost circuit 200, as well as the power supply voltage.

[0039] Next, we will explain an example of the operation of the fuel injection valve control device 1 using the flowchart in Figure 2 and the timing chart in Figure 3.

[0040] When control of the boost operation is started (step S1), first the current table selector 40 selects table A from the upper and lower limit current setting value tables A and B, which are the boost control currents, in the current table 45 (step S2).

[0041] As shown in Figure 3, the relationship between the two upper and lower current limit setting tables A and B is "Table B < Table A" for the boost average current. Table A contains upper and lower current limit settings suitable when all parallel-connected boost circuits are functioning correctly, while Table B contains upper and lower current limit settings suitable when one boost circuit fails.

[0042] In this embodiment, since there are two boost circuits in parallel, there are two current tables 45. However, if the number of parallel boost circuits is three or more, the same number of tables as the number of parallel boost circuits will be prepared. The relationship between the upper and lower limit current settings and the average boost current will be such that table A will be the upper and lower limit current settings appropriate when all boost circuits are functioning normally, and the second and subsequent tables will be set to upper and lower limit current settings appropriate for each additional number of faulty boost circuits.

[0043] Furthermore, the relationship between the boost average currents of each table is such that the table best suited for a large number of faulty circuits has a lower boost average current. For example, if there are three boost circuits in parallel, three tables, A, B, and C, are prepared, and the relationship between their boost average currents is "Table C < Table B < Table A".

[0044] Table A shows the upper and lower current limit settings suitable when all parallel-connected boost circuits are functioning correctly, Table B shows the upper and lower current limit settings suitable when one boost circuit fails, and Table C shows the upper and lower current limit settings suitable when two boost circuits fail.

[0045] The boost setting controller 35, which has selected table A of the upper and lower limit current setting values ​​using the current table selection device 40, issues a command to the fuel injection control IC 25 to set the upper and lower limit currents.

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

[0047] During boost control, the current interruption controller 300 performs ON / OFF control of the upstream current interruption circuits 110, 210 and the downstream current interruption circuits 111, 211 based on circuit fault information of the boost circuit.

[0048] The arithmetic unit 30 determines whether or not there is a fault in the boost circuit 100 based on the input circuit fault information (step S4).

[0049] If the boost circuit 100 is found to be faulty based on fault information (YES), the boost circuit 100 and boost circuit 200 are stopped from boosting (step S5), and the upstream stage current interruption circuit 110 and the downstream stage current interruption circuit 111 are turned OFF (step S6), thereby interrupting the current I flowing from the power supply into the boost circuit 100.

[0050] Subsequently, the arithmetic unit 30 determines whether or not there is a fault in the boost circuit 200 based on the input circuit fault information (step S7).

[0051] If the boost circuit 200 is found to be faulty based on fault information (YES), the upstream stage current interruption circuit 210 and the downstream stage current interruption circuit 211 are turned OFF (step S8), thereby interrupting the current I flowing from the power supply to the boost circuit 200 and terminating the boost control (step S13).

[0052] In step S7, if it is detected that the boost circuit 200 is not malfunctioning (functioning normally) (NO), the current table selector 40 selects table B of the upper and lower limit current setting values ​​(step S12), issues a command to the fuel injection control IC 25 to set the upper and lower limit currents, and the fuel injection control IC 25 starts the boost operation by the boost circuit 200.

[0053] On the other hand, if step S4 detects that the boost circuit 100 is not faulty (functioning normally) (NO), then step S9 determines whether the boost circuit 200 is faulty based on the input circuit fault information.

[0054] If fault information for the boost circuit 200 indicates that the boost circuit 200 is faulty (YES), the boosting of the boost circuit 200 and the boost circuit 100 is stopped (step S10), and the upstream stage current interruption circuit 210 and the downstream stage current interruption circuit 211 are turned OFF (step S11) to interrupt the current flowing from the power supply to the boost circuit 200. Then, the current table selector 40 selects table B of the upper and lower limit current setting values ​​(step S12), and a command is issued to the fuel injection control IC 25 to set the upper and lower limit currents, and the fuel injection control IC 25 starts the boosting operation by the boost circuit 100.

[0055] Furthermore, if step S9 detects that the boost circuit 200 is not faulty (functioning normally) (NO), then, since no failure has occurred in the boost circuit along with the boost circuit 100, boost control continues with the upper and lower limit current setting values ​​in table A (step S3).

[0056] In the flowchart in Figure 2, processing is performed starting with the failure information of the boost circuit 100. However, it is also conceivable that processing could be performed starting with the failure information of the boost circuit 200, or that the failure information of both boost circuits 100 and 200 could be processed simultaneously. Furthermore, the failure information of the boost circuits input to the arithmetic unit 30 is expected to include information obtained from the fuel injection control IC 25, information determined by the arithmetic unit 30 itself, and information obtained by a failure detection circuit (not shown).

[0057] In this embodiment, by interrupting the current flowing from the power supply to the faulty boost circuit, the faulty boost circuit is electrically isolated, and by changing the upper and lower current limit settings to those suitable for the remaining boost circuits, the other boost circuits that are not faulty can continue boosting without thermal damage due to boosting losses.

[0058] This ensures a continuous supply of energy to open the fuel injectors, preventing engine shutdown caused by a failure in one circuit in the parallel circuit.

[0059] Furthermore, by interrupting the current that continues to flow from the power supply to the faulty circuit, it becomes possible to prevent secondary failures such as thermal burnout of the circuit board due to further overheating of the faulty circuit portion, dielectric breakdown of capacitors in the boost circuit, and destruction of the power supply circuit that supplies current to the boost circuit, which would otherwise occur if the power supply current continues to flow to the faulty circuit. [Examples]

[0060] A fuel injection valve control device and its control method according to Embodiment 2 of the present invention will be described with reference to Figures 4 and 5.

[0061] Figure 4 is a functional block diagram of the fuel injection valve control device 1 of this embodiment. Figure 5 is a flowchart showing the control method of the fuel injection valve control device 1 of Figure 4.

[0062] In Example 1 (Figure 1), the ON / OFF control of the upstream and downstream current interruption circuits provided in each boost circuit is performed simultaneously from the current interruption controller 300 for each boost circuit. However, in this Example (Figure 4), the ON / OFF control of the upstream and downstream current interruption circuits is configured to be independently controlled by each interruption circuit.

[0063] The basic components of a boost circuit include a boost coil, a boost driver (FET), a boost diode, and a boost capacitor. If any of these components short-circuit to GND, the power supply current will flow into the faulty circuit, making it impossible for all parallel-connected boost circuits to continue boosting voltage. However, if any of the above components short-circuit, the power supply current will not flow into the faulty circuit, and therefore no secondary failures will occur.

[0064] If a boost converter circuit has all its components functioning correctly, it can continue boosting the voltage without interrupting the current. Furthermore, if the boost capacitor is not faulty, it can act as a rechargeable battery for the otherwise functioning boost converter circuit.

[0065] The same applies to a short-circuit failure of a boost driver (FET). In the event of a short-circuit failure of a boost driver (FET), if the current flowing to the short-circuited boost driver (FET) can be interrupted, and the boost capacitor is not faulty, it is possible to continue using the boost capacitor as a rechargeable battery.

[0066] In Example 1 (Figure 1), the configuration simultaneously controls the ON / OFF states of the upstream and downstream current interruption circuits in each boost circuit. Based on fault detection, the current interruption circuit is turned OFF, electrically isolating the entire faulty boost circuit from the normal boost circuit. Therefore, even if the boost capacitor of the faulty boost circuit is still usable, it is not possible to continue using it as a rechargeable battery.

[0067] Therefore, in this embodiment, by configuring the upstream and downstream current interruption circuits to be controlled independently of each other, it becomes possible to turn OFF only the upstream current interruption circuit in the event of a short-circuit failure in the boost driver (FET), thereby interrupting the current flowing into the short-circuited boost driver (FET). Furthermore, the current flowing back from the non-faulty boost circuit to the short-circuited boost driver (FET) is prevented by the boost diode, which is a basic component of the boost circuit, thereby electrically isolating the short-circuited boost driver (FET).

[0068] An example of the operation of the fuel injection valve control device 1 in this embodiment will be explained using the flowchart in Figure 5.

[0069] When control of the boost operation is started (step S1), the current table selector 40 first selects table A from the upper and lower limit current setting value tables A and B, which are the boost control currents, 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 in Embodiment 1.

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

[0071] Next, the arithmetic unit 30 determines whether or not there is a fault in the boost circuit 100 based on the input circuit fault information (step S4).

[0072] If the boost circuit 100 is found to be faulty based on its fault information (YES), the boost circuit 100 and boost circuit 200 are stopped (step S5).

[0073] Next, the arithmetic unit 30 determines, based on the input circuit fault information, whether the fault occurring is solely a short circuit fault in the boost driver (FET) 102 (step S6).

[0074] If it is detected that the only fault occurring is a short circuit in the boost driver (FET) 102 (YES), the upstream stage current interruption circuit 110 is turned OFF (step S7) to prevent current I from flowing from the power supply to GND through the faulty boost driver (FET) 102.

[0075] Next, the arithmetic unit 30 determines whether or not there is a fault in the boost circuit 200 based on the input circuit fault information (step S8).

[0076] If the boost circuit 200 is found to be faulty based on fault information (YES), the upstream stage current interruption circuit 210 and the downstream stage current interruption circuit 211 are turned OFF (step S9), thereby interrupting the current I flowing from the power supply to the boost circuit 200 and terminating the boost control (step S18).

[0077] On the other hand, if step S4 detects that the boost circuit 100 is not faulty (functioning normally) (NO), then step S10 determines whether the boost circuit 200 is faulty based on the input circuit fault information.

[0078] If the boost circuit 200 is found to be faulty based on its fault information (YES), the boosting of both the boost circuit 200 and the boost circuit 100 is stopped (step S11).

[0079] Next, the arithmetic unit 30 determines, based on the input circuit fault information, whether the fault occurring is solely a short circuit fault in the boost driver (FET) 202 (step S12).

[0080] If it is detected that the only fault occurring is a short circuit in the boost driver (FET) 202 (YES), the upstream stage current interruption circuit 210 is turned OFF (step S13) to prevent current I from flowing from the power supply to GND through the faulty boost driver (FET) 202.

[0081] Subsequently, the current table selector 40 selects table B of the upper and lower limit current setting values ​​(step S14), issues a command to the fuel injection control IC 25 to set the upper and lower limit currents, and the fuel injection control IC 25 continues the boosting operation by the boost circuit 100.

[0082] In step S12, if it is detected that the fault occurring is not a short-circuit fault of the boost driver (FET) 202 (NO), the arithmetic unit 30 determines, based on the input circuit fault information, whether the fault occurring is solely an open-circuit fault of the boost driver (FET) 202 (step S16).

[0083] If it is detected that the only fault occurring is an open fault in the boost driver (FET) 202 (YES), then the components of the boost circuit 200 other than the boost driver (FET) 202 remain available, and the boost operation by the boost circuit 100 continues.

[0084] On the other hand, if it is detected that the fault occurring is not an open fault in the boost driver (FET) 202 (NO), the upstream stage current interruption circuit 210 and the downstream stage current interruption circuit 211 are turned OFF (step S17), electrically isolating the boost circuit 200 and continuing the boost operation by the boost circuit 100.

[0085] In step S6, if it is detected that the fault occurring is not a short circuit fault in the boost driver (FET) 102 (NO), the arithmetic unit 30 determines, based on the input circuit fault information, whether the fault occurring is solely an open circuit fault in the boost driver (FET) 102 (step S15).

[0086] If it is detected that the only fault occurring is an open fault in the boost driver (FET) 102 (YES), then the components of the boost circuit 100 other than the boost driver (FET) 102 remain available, and the boost operation by the boost circuit 200 continues.

[0087] On the other hand, if it is detected that the fault occurring is not an open fault in the boost driver (FET) 102 (NO), the upstream stage current interruption circuit 110 and the downstream stage current interruption circuit 111 are turned OFF (step S19), electrically isolating the boost circuit 100 and continuing the boost operation by the boost circuit 200.

[0088] In this embodiment, by configuring the current interruption circuits to be controlled independently of each other, it becomes possible to continue using the boost capacitor as a rechargeable battery when it is still available.

[0089] Furthermore, if the open fault is located in any of the boost coil, boost driver (FET), or boost diode, the same effect as in the case of a boost driver (FET) failure can be achieved by preventing the current cutoff circuit from being turned OFF.

[0090] However, in the event of failure of any component, in order to prevent thermal damage to the remaining boost circuits and continue boosting the voltage, it is necessary to switch to upper and lower current limit settings appropriate for the number of remaining boost circuits. Therefore, as in Example 1, the boosting is stopped, the optimal table for upper and lower current limit settings corresponding to the number of remaining circuits is selected, and the current cutoff circuit is turned ON to continue supplying current while the boosting is restarted. [Examples]

[0091] Referring to Figure 6, a fuel injection valve control device and its control method according to Embodiment 3 of the present invention will be described. Figure 6 is a functional block diagram of the fuel injection valve control device 1 of this embodiment.

[0092] As shown in Figure 6, the fuel injection valve control device 1 of this embodiment differs from Embodiments 1 (Figure 1) and 2 (Figure 4) in that it replaces the downstream stage current interruption circuits 111 and 211 of Embodiments 1 (Figure 1) and 2 (Figure 4) with downstream stage current reverse flow prevention diodes 112 and 212 on the respective voltage output sides of the boost circuit 100 and boost circuit 200. The other configurations are the same as those of Embodiments 1 (Figure 1) and 2 (Figure 4).

[0093] The circuit configuration is as follows: the downstream stage current cutoff circuit 111 is replaced with a downstream stage current reverse flow prevention diode 112, and the downstream stage current cutoff circuit 211 is replaced with a downstream stage current reverse flow prevention diode 212.

[0094] When boost capacitors 104 and 204 short-circuit, in order to electrically isolate the failed boost circuit, it is necessary to block the reverse current flow from the output side of other parallel circuits in addition to the current flow from the power supply. Therefore, by connecting the anode side of the downstream current reverse current prevention diodes 112 and 212 to the output side of the boost circuit and arranging them so that the cathode side is on the voltage output side, it becomes possible to block the reverse current flow from the output side of other parallel circuits.

[0095] In this embodiment, by changing the downstream stage current interruption circuit to a downstream stage current reverse flow prevention diode, it becomes unnecessary to control the ON / OFF state of the downstream stage current interruption circuit, thus reducing the circuit drive load required to operate the downstream stage current interruption circuit from the computing unit 30. [Examples]

[0096] Referring to Figure 7, a fuel injection valve control device and its control method according to Embodiment 4 of the present invention will be described. Figure 7 is a functional block diagram of the fuel injection valve control device 1 of this embodiment.

[0097] As shown in Figure 7, the fuel injection valve control device 1 of this embodiment differs from Embodiment 1 (Figure 1) and Embodiment 2 (Figure 4) in that it replaces the upstream current interruption circuits 110, 210 and downstream current interruption circuits 111, 211 of Embodiment 1 (Figure 1) and Embodiment 2 (Figure 4) with autonomous current interruption mechanisms 113, 114, 213, and 214, respectively. The other configurations are the same as those of Embodiment 1 (Figure 1) and Embodiment 2 (Figure 4).

[0098] The circuit configuration involves replacing the upstream and downstream current interruption circuits with elements that can autonomously interrupt the current when a certain level of current is exceeded, such as fuses.

[0099] In this embodiment, the upstream and downstream current interruption circuits are modified to include elements that can autonomously interrupt current when a current exceeding a certain level flows through them. This makes it possible to immediately electrically isolate a faulty circuit when an overcurrent exceeding the expected level flows through the circuit.

[0100] This further reduces the risk of secondary failures, such as thermal burnout of the circuit board due to further heat generation in the faulty circuit caused by the continued flow of power supply current to the faulty circuit, and damage to the power supply circuit that supplies current to the boost circuit.

[0101] Furthermore, since the arithmetic unit 30 does not need to control the ON / OFF state of the current interruption circuit, the circuit drive load required for current interruption by the arithmetic unit 30 can be reduced.

[0102] In the embodiments described above, a fuel injection valve control device for driving and controlling a fuel injection valve was used as an example of a load drive device. However, parallel boost circuits are widely envisioned to have applications in drive devices for driving high-output motors in automotive equipment, load drive devices requiring high voltage boosting, load drive devices where charging speed is important, etc., for the purpose of reducing the circuit burden due to heat loss per circuit. The present invention can be applied to all such load drive measures.

[0103] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. Also, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations. [Explanation of symbols]

[0104] 1…Fuel injection valve control device (load drive device), 2…Fuel injection valve (load), 20…Voltage monitor, 25…Fuel injection control IC, 30…Calculation unit, 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 stage current cutoff circuit, 111,211…Downstream stage current cutoff circuit, 112,212…Downstream stage current reverse flow prevention diode, 113,114,213,214…Autonomous current cutoff mechanism, 300…Current cutoff controller.

Claims

1. The first boost circuit and A second boost circuit connected in parallel to the first boost circuit, A first current interruption circuit is located on the upper side of the first boost circuit, A second current interruption circuit is located on the lower side of the first boost circuit, A third current interruption circuit is located on the upper side of the second boost circuit, A fourth current interruption circuit is located on the lower side of the second boost circuit, The system comprises a computing device that calculates control commands for controlling the first boost circuit and the second boost circuit, The aforementioned computing device, when it detects a failure in the first boost circuit, cuts off the current from the power supply to the first boost circuit using the first current cutoff circuit, and changes the current setting value of the second boost circuit to a lower value than before the failure, thereby operating the second boost circuit.

2. A load drive device according to claim 1, The aforementioned computing device detects a failure in the first boost circuit, and if it detects that the detected failure is a short-circuit failure in a component constituting the first boost circuit, it cuts off the current from the power supply to the first boost circuit using the first current cut-off circuit and cuts off the current from the second boost circuit to the first boost circuit using the second current cut-off circuit.

3. A load drive device according to claim 1, The load drive device is a diode in which the second current interruption circuit and the fourth current interruption circuit are arranged such that the anode side is connected to the output side of the first boost circuit and the second boost circuit, and the cathode side is the voltage output side.

4. A load drive device according to claim 1, The first current interruption circuit, the second current interruption circuit, the third current interruption circuit, and the fourth current interruption circuit are load drive devices that autonomously interrupt the current when a current exceeding a certain level flows through them.

5. A load drive device according to claim 1, A load drive device that stops the boosting operation of the first boost circuit and the second boost circuit before changing the current setting value of the second boost circuit to a lower value.

6. A load drive device according to claim 1, The arithmetic unit detects a failure in the first boost circuit, and if it detects that the detected failure is an open circuit failure in a component constituting the first boost circuit, it is a load drive device that does not interrupt the current using the first current interruption circuit, the second current interruption circuit, the third current interruption circuit, and the fourth current interruption circuit.

7. A load drive device according to claim 1, The first current interruption circuit, the second current interruption circuit, the third current interruption circuit, and the fourth current interruption circuit are load drive devices that can be controlled independently of each other.

8. A load drive device according to claim 1, The aforementioned computing device detects a failure in the first boost circuit, and if it detects that the detected failure is a short-circuit failure in the boost driver constituting the first boost circuit, it operates only the first current interruption circuit to interrupt the current from the power supply to the first boost circuit.

9. A control method for a load drive device having multiple boost circuits connected in parallel, (a) A step to detect a failure in the boost circuit, (b) A step of interrupting the current to the faulty boost circuit based on the fault information detected in step (a), (c) After step (b), the step of operating the boost circuits other than the faulty boost circuit by changing the current setting value of the boost circuits other than the faulty boost circuit to a lower value than before the failure, A control method for a load drive device having the following features.

10. A control method for a load drive device according to claim 9, A control method for a load drive device, wherein if the fault detected in step (a) above is a short-circuit fault in 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 also cut off.

11. A control method for a load drive device according to claim 9, A control method for a load drive device that stops the boosting operation of the plurality of boost circuits before step (c).

12. A control method for a load drive device according to claim 9, A control method for a load drive device in which the current is not interrupted in step (b) if the fault detected in step (a) is an open fault of a component constituting the boost circuit.

13. A control method for a load drive device according to claim 9, A control method for a load drive device that, when the fault detected in step (a) above is a short-circuit fault in a boost driver constituting a boost circuit, cuts off only the current from the power supply to the faulty boost circuit.

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