Load driving device

Abstract

A load driving device according to one aspect of the present invention comprises: a synchronous rectification-type load drive circuit that drives a solenoid; an upstream-side current monitoring unit that detects the current flowing to an upstream-side output element of the load drive circuit; a downstream-side current monitoring unit that detects the current flowing to a downstream-side output element of the load drive circuit; and a diagnosis unit that compares the current value detected by the upstream-side current monitoring unit with the current value detected by the downstream-side current monitoring unit, and makes a diagnosis on the basis of the comparison result.

Description

Load driver

[0001] The present invention relates to a load driving device mounted on a vehicle.

[0002] 2. Description of the Related Art A drive control device that drives a solenoid to control hydraulic pressure in a transmission is known as one of on-board control devices installed in a vehicle.

[0003] In the solenoid current control of the drive control device, if a discrepancy occurs between the target current value and the current value actually flowing through the solenoid, problems may occur such as sudden deceleration due to abnormal gear shifting (sudden shift to low gear) or a feeling of freewheeling due to engine braking being interrupted (sudden shift to high gear), etc. To address these problems, Patent Document 1 discloses a technology for diagnosing a load drive device equipped with a synchronous rectifier circuit.

[0004] The technology described in Patent Document 1 includes a synchronous rectifier circuit having a drive-side switching element and a freewheel-side switching element, a driver control circuit that controls the synchronous rectifier circuit, and a voltage monitor circuit that monitors the voltage at the output terminal of the synchronous rectifier circuit. When the driver control circuit receives a diagnostic command, the technology described in Patent Document 1 controls both the drive-side switching element and the freewheel-side switching element to be turned OFF, and monitors the voltage while both are OFF. This shortens the diagnostic time required to detect the presence or absence of a pulse in the output voltage.

[0005] International Publication No. 2019 / 220716

[0006] However, the technology described in Patent Document 1 aims to shorten the diagnostic time for pulse detection, and has the problem that it cannot detect anomalies in the current accuracy of a current monitor that monitors the current of a synchronous rectifier circuit. An anomaly in the current accuracy of the current monitor is an error in the monitored current that exceeds the allowable error.

[0007] In view of the above circumstances, there has been a demand for a method that can detect an abnormality in the current accuracy of a current monitor section in a synchronous rectifier circuit.

[0008] In order to solve the above problem, a load driving device according to one embodiment of the present invention comprises a synchronous rectification type load driving circuit that drives a solenoid, an upstream current monitoring unit that detects the current flowing in the upstream output element of the load driving circuit, a downstream current monitoring unit that detects the current flowing in the downstream output element of the load driving circuit, and a diagnostic unit that compares the current value detected by the upstream current monitoring unit with the current value detected by the downstream current monitoring unit and performs a diagnosis based on the comparison result.

[0009] According to at least one aspect of the present invention, a load drive circuit includes an upstream current monitor unit and a downstream current monitor unit, and a diagnostic unit that compares the current values ​​of the load drive circuit of a synchronous rectification type, thereby making it possible to detect an abnormality in the current accuracy of the current monitor unit. Problems, configurations, and effects other than those described above will become clear from the description of the following embodiments.

[0010] FIG. 1 is a diagram showing an example of the internal configuration of an on-board control device according to a first embodiment of the present invention; FIG. 2 is a diagram showing an example of operational waveforms when the monitored current values ​​of the upstream output element and the downstream output element are normal in the on-board control device according to the first embodiment of the present invention; FIG. 3 is a diagram showing an example of operational waveforms (abnormality diagnosis based on average current) when the monitored upstream current value of the upstream output element is normal and the monitored downstream current value of the downstream output element is abnormal in the on-board control device according to the first embodiment of the present invention; FIG. 4 is a diagram showing an example of operational waveforms (abnormality diagnosis based on capture values) when the monitored upstream current value of the upstream output element is normal and the monitored downstream current value of the downstream output element is abnormal in the on-board control device according to a second embodiment of the present invention; FIG. 5 is a diagram showing an example of the internal configuration (diagnosis configuration based on a microcomputer) of an on-board control device according to a third embodiment of the present invention; FIG. 6 is a block diagram showing an example of the hardware configuration of a microcomputer included in the on-board control device according to the third embodiment of the present invention; and FIG. 7 is a diagram showing an example of the internal configuration (diagnosis configuration based on a hardware logic circuit) of an on-board control device according to a fourth embodiment of the present invention.

[0011] Hereinafter, examples of modes for carrying out the present invention (hereinafter referred to as "embodiments") will be described with reference to the accompanying drawings. In this specification and the accompanying drawings, identical components or components having substantially the same functions will be assigned the same reference numerals, and redundant description will be omitted. Furthermore, when there are multiple components having the same or similar functions, they may be described using the same reference numerals with different subscripts. Note that when it is not necessary to distinguish between these multiple components, the subscripts may be omitted in the description. The number of each component may be singular or plural unless otherwise specified.

[0012] First Embodiment First, an on-vehicle control device according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG.

[0013] 1 is a diagram showing an example of the internal configuration of an on-board control device according to embodiment 1. The on-board control device 10 is an example of a load driving device, and controls an on-board system by driving a solenoid 21 based on information from the vehicle side, etc.

[0014] 1, the on-board control device 10 has a power supply connector 11 and a solenoid connector 12. One end of the power supply connector 11 of the on-board control device 10 is connected to a power supply 20, and the other end of the power supply 20 is connected to ground (GND). Furthermore, one end of the solenoid connector 12 of the on-board control device 10 is connected to a solenoid 21, and the other end of the solenoid 21 is connected to ground (GND). In this embodiment, only one power supply 20 and one solenoid 21 are connected to the on-board control device 10, but there may be a configuration in which multiple power supplies and solenoids are connected.

[0015] The on-board control device 10 is composed of a target current instruction unit 30, a feedback control unit 31, a driver control unit 32, a load drive circuit 39 (upstream output element 33, downstream output element 34), an upstream current monitor unit 35, a downstream current monitor unit 36, a current calculation unit 37, and a diagnosis unit 38.

[0016] The upstream output element 33 and the downstream output element 34 are connected in series to form a synchronous rectification type load drive circuit 39. For example, the upstream output element 33 and the downstream output element 34 are power semiconductor elements such as N-channel MOSFETs.

[0017] The drain terminal of the upstream output element 33 is connected to the power supply connector 11. The source terminal of the upstream output element 33 is connected to the drain terminal of the downstream output element 34, and the source terminal of the downstream output element 34 is connected to GND. The midpoint of connection between the source terminal of the upstream output element 33 and the drain terminal of the downstream output element 34 is connected to the solenoid connector 12. A free wheel diode is connected between the drain and source of each of the upstream output element 33 and the downstream output element 34.

[0018] The target current instruction unit 30 instructs the feedback control unit 31 on the target current when driving the solenoid 21. For example, the target current value is calculated and determined by a predetermined control program that controls the in-vehicle system.

[0019] The feedback control unit 31 receives the current that actually flows through the solenoid 21 when the solenoid 21 is driven (hereinafter referred to as the "actual current") and performs calculations to make the actual current equal to the target current. In this embodiment, the current value calculated by the current calculation unit 37 (current monitor value 48) is used as the current value of the current that actually flows through the solenoid 21.

[0020] The driver control unit 32 supplies drive signals (a first PWM signal 41 and a second PWM signal 42 ) to the load drive circuit 39 in accordance with instructions (a PWM (Pulse Width Modulation) signal 40 ) from the feedback control unit 31 , thereby driving the solenoid 21 .

[0021] The load drive circuit 39 is configured as a synchronous rectification type load drive circuit in which an upstream output element 33 and a downstream output element 34 are connected in series. The load drive circuit 39 is a synchronous rectification circuit. The upstream output element 33 is connected to the power supply 20 side (upstream side) and performs ON / OFF operation in accordance with instructions (first PWM signal 41) from the driver control unit 32. The downstream output element 34 is connected to the ground side (downstream side) and performs ON / OFF operation in accordance with instructions (second PWM signal 42) from the driver control unit 32.

[0022] The upstream current monitor unit 35 monitors the current flowing through the upstream output element 33 and sends the current value (upstream current monitor value 46) to the current calculation unit 37. The downstream current monitor unit 36 ​​monitors the current flowing through the downstream output element 34 and sends the current value (downstream current monitor value 47) to the current calculation unit 37.

[0023] The current calculation unit 37 calculates the value of the current actually flowing through the solenoid 21 from the current monitor value output from the upstream current monitor unit 35 and the current monitor value output from the downstream current monitor unit 36. The current calculation unit 37 sends the calculation result (current monitor value 48) to the diagnosis unit 38.

[0024] The diagnostic unit 38 receives the current monitor value of the upstream current monitor unit 35 and the current monitor value of the downstream current monitor unit 36, and diagnoses whether there is an abnormality in the current value of either the upstream current monitor unit 35 or the downstream current monitor unit 36. The diagnostic unit 38 also sends the diagnostic result (diagnosis result signal 49) to the feedback control unit 31.

[0025] Generally, the upstream output element 33 and the downstream output element 34 are packaged (modularized) like the load drive circuit 39. Therefore, even if it is only possible to know that an abnormality has occurred in at least the upstream or downstream current monitor section, there is an advantage in terms of taking measures such as replacing parts.

[0026] According to this embodiment, a current monitoring unit (upstream current monitoring unit 35 or downstream current monitoring unit 36) is provided for each of the upstream output element 33 and downstream output element 34, which are driver elements that drive the solenoid 21. This embodiment is characterized by having a diagnosing unit 38 that receives an upstream current monitored value 46 and a downstream current monitored value 47 from the upstream current monitoring unit 35 and the downstream current monitoring unit 36, and diagnoses whether or not each of the current monitored values ​​is abnormal.

[0027] [Operation of the Vehicle-Mounted Control Device] Next, a description will be given of the operation of the vehicle-mounted control device 10. First, a target current value is input to the feedback control unit 31 from the target current instruction unit 30 that calculates a target current value from information on the vehicle side, etc.

[0028] The feedback control unit 31 compares the current value of the actual current flowing through the solenoid 21, which is the control target connected to the on-board control device 10, with the target current value, and performs feedback control so that the actual current of the solenoid 21 coincides with the target current value. The feedback control unit 31 inputs a PWM signal 40, which is an instruction signal, to a driver control unit 32, which generates drive signals for controlling the upstream output element 33 and the downstream output element 34.

[0029] In the present embodiment, the instruction signal from the feedback control unit 31 to the driver control unit 32 is described as a PWM signal, but the present invention is not limited to this example. For example, it goes without saying that the instruction signal can be realized by a signal other than a PWM signal, such as an SPI (Serial Peripheral Interface) signal.

[0030] SPI is a data transmission path standard that employs a serial communication method via a serial bus. SPI operates in a master / slave format, with roles divided between the control side (master) and the controlled side (slave), and various signals are communicated over four signal lines. For example, if there are four sets of upstream and downstream output elements (load drive circuits), using PWM signals would require sending four PWM signals for each set to the driver control unit 32. Using SPI signals, it is sufficient to send a single SPI signal carrying information on four instruction signals for each set to the driver control unit 32 via serial communication. The SPI signal can also be used to send and receive each current monitor value.

[0031] The driver control unit 32 inputs a first PWM signal 41 to the upstream output element 33 based on the PWM signal 40. Similarly, the driver control unit 32 inputs a second PWM signal 42 to the downstream output element 34 based on the PWM signal 40.

[0032] As described above, the upstream output element 33 and the downstream output element 34 are configured as a synchronous rectification type load drive circuit 39. Therefore, when the upstream output element 33 is ON and the downstream output element 34 is OFF, an upstream current 43 flows through the solenoid 21. Conversely, when the upstream output element 33 is OFF and the downstream output element 34 is ON, a downstream current 44 flows as a return current.

[0033] By this operation, a solenoid current 45, which is the sum of the upstream current 43 and the downstream current 44, flows through the solenoid 21. The upstream current 43 that flows through the upstream output element 33 has its current value (upstream current monitor value 46) detected by the upstream current monitor unit 35, and the upstream current monitor value 46 is input to the current calculation unit 37. Similarly, the downstream current 44 that flows through the downstream output element 34 has its current value (downstream current monitor value 47) detected by the downstream current monitor unit 36, and the downstream current monitor value 47 is input to the current calculation unit 37.

[0034] The current calculation unit 37 receives the upstream current monitor value 46 and the downstream current monitor value 47, adds them together, and sends the resulting summed current monitor value 48 to the feedback control unit 31 as the current value of the solenoid current 45. The upstream current monitor value 46 and the downstream current monitor value 47 are also sent to the diagnosis unit 38.

[0035] The diagnostic unit 38 compares the upstream current monitor value 46 and the downstream current monitor value 47, and if there is a significant difference (for example, a difference of 10% or more), it determines that an abnormality has occurred in either the upstream current monitor unit 35 or the downstream current monitor unit 36, and inputs a diagnostic result signal 49 to the feedback control unit 31. If there is no significant difference between the two, the diagnostic unit 38 does not output the diagnostic result signal 49.

[0036] If the diagnosis result signal 49 input from the diagnosis unit 38 contains information indicating an abnormality in the current monitor unit, the feedback control unit 31 performs control to act on the safety side for the in-vehicle system to which the solenoid 21 is applied. For example, the feedback control unit 31 performs an operation to stop the solenoid current 45 flowing to the solenoid 21 or fix the solenoid current 45 at a constant value.

[0037] [Signal Waveforms of Each Part (Normal Case)] Here, the signal waveforms of each part of the on-board control device 10 will be described with reference to Fig. 2. Fig. 2 is a diagram showing an example of operational waveforms in the on-board control device 10 when the current monitor values ​​of the upstream output element 33 and the downstream output element 34 are normal.

[0038] The drive waveform of the first PWM signal 41 supplied to the upstream output element 33 is referred to as a "first PWM signal waveform 201," and the current waveform generated in the upstream output element 33 by the first PWM signal waveform 201 is referred to as an "upstream current waveform 202." Furthermore, the drive waveform of the second PWM signal 42 supplied to the downstream output element 34 is referred to as a "second PWM signal waveform 203," and the current waveform generated in the downstream output element 34 by the second PWM signal waveform 203 is referred to as a "downstream current waveform 204." Furthermore, the signal waveform generated by the current calculation unit 37 is referred to as a "current calculation unit waveform 205," and the signal waveform generated by the diagnosis unit 38 is referred to as a "diagnosis unit waveform (average value) 206."

[0039] The first PWM signal waveform 201 and the second PWM signal waveform 203 are waveforms in which the ON and OFF states are opposite to each other in the synchronous rectification type load drive circuit 39 to which the present invention is applied.

[0040] During the period when the first PWM signal waveform 201 is ON, the upstream output element 33 is ON, and therefore a current (upstream current 43) flows from the power supply 20 to the upstream output element 33. Therefore, the upstream current waveform 202 (upstream current monitor value 46) operates so that the current gradually increases until the upstream output element 33 is turned OFF. During the period when the upstream output element 33 is OFF, the upstream current 43 does not flow.

[0041] During the period when the second PWM signal waveform 203 is ON, the downstream output element 34 is ON, and the return current (downstream current 44) that has flowed via ground (GND) flows into the downstream output element 34. Therefore, the downstream current waveform 204 (downstream current monitor value 47) operates so that the return current gradually decreases (discharges) until the downstream output element 34 is turned OFF. During the period when the downstream output element 34 is OFF, the downstream current 44 does not flow.

[0042] While the first PWM signal 41 and the second PWM signal 42 of the driver control unit 32 are operating, the above operations are repeated in the upstream output element 33 and the downstream output element 34, as well as the upstream current monitor unit 35 and the downstream current monitor unit 36.

[0043] The upstream current waveform 202 and the downstream current waveform 204 are combined in the current calculation unit 37 to produce a charge / discharge waveform such as the current calculation unit waveform 205. This waveform becomes the current monitor value 48 that represents the solenoid current 45 that actually flows through the solenoid 21.

[0044] The diagnostic unit 38 calculates the average current value of the upstream current waveform 202 during the ON period and the average current value of the downstream current waveform 204 during the ON period, and compares these average values. The calculation result of the average current values ​​becomes a waveform like the diagnostic waveform 206.

[0045] If the difference between the average value of the upstream current waveform 202 and the average value of the downstream current waveform 204 is less than a predetermined value (e.g., 10%), the diagnostic unit 38 determines that the upstream current monitor value 46 and the downstream current monitor value 47 are normal.

[0046] On the other hand, if the difference between the average value of the upstream current waveform 202 and the average value of the downstream current waveform 204 exceeds the normal value (see FIG. 3 ), the diagnostic unit 38 determines that the upstream current monitor value 46 or the downstream current monitor value 47 is abnormal. Then, the diagnostic unit 38 sends the determination result as a diagnostic result signal 49 to the feedback control unit 31.

[0047] [Signal Waveforms of Each Part (In Case of Abnormality)] Next, a diagnostic method for when the monitored current value of the upstream output element 33 or the downstream output element 34 is abnormal in the on-board control device 10 will be described with reference to Fig. 3. Here, the diagnostic method for when the monitored current value of the downstream output element 34 (downstream current monitor unit 36) is abnormal will be described using operational waveforms.

[0048] FIG. 3 is a diagram showing an example of operating waveforms (abnormality diagnosis based on average current) when the upstream current monitor value 46 of the upstream output element 33 is normal and the downstream current monitor value 47 of the downstream output element 34 is abnormal in the on-board control device 10.

[0049] The downstream current waveform when the downstream current monitor unit 36 ​​is abnormal is referred to as "downstream current waveform 301," and the signal waveform generated by the current calculation unit 37 when the downstream current monitor unit 36 ​​is abnormal is referred to as "current calculation unit waveform 302." Furthermore, the signal waveform generated by the diagnosis unit 38 when the downstream current monitor unit 36 ​​is abnormal is referred to as "diagnosis unit waveform (average value) 303."

[0050] In this embodiment, the downstream current waveform 301 during an abnormal state is detected as a current value that is smaller than the downstream current waveform 204 during a normal state. Since the upstream current monitor unit 35 is normal, the upstream current waveform 202 indicates a normal value.

[0051] The normal upstream current waveform 202 and the abnormal downstream current waveform 301 are combined in the current calculation unit 37, and the combined waveform at this time is shown as the current calculation waveform 302. The abnormal current calculation waveform 302 is a waveform different from the normal current calculation waveform 205. The current value calculated from this waveform is small compared to the actual current flowing through the solenoid 21.

[0052] However, if an incorrect current value is input to the feedback control unit 31 as the current monitor value 48, the feedback control unit 31 will perform control based on the incorrect current monitor value 48. This may cause a risk of malfunction in the vehicle system in which the solenoid 21 is used.

[0053] Here, a normal upstream current waveform 202 and a downstream current waveform 301 with an abnormal downstream current monitor value 47 are input to the diagnostic unit 38. The diagnostic unit 38 compares the average value of the current value detected by the upstream current monitor unit 35 (upstream current monitor value 46) with the average value of the current value detected by the downstream current monitor unit 36 ​​(downstream current monitor value 47).

[0054] In the example of Fig. 3, when the diagnostic unit 38 compares the average current value during the ON period of the normal upstream current waveform 202 with the average current value during the ON period of the abnormal downstream current waveform 301, a large deviation occurs, as shown in the diagnostic waveform (average value) 303. When the upstream current waveform 202 and the downstream current waveform 204 are normal as shown in Fig. 2, the diagnostic waveform 206 is a straight line. On the other hand, when the upstream current waveform 202 is normal and the downstream current waveform 301 is abnormal as shown in Fig. 3, a step occurs in the diagnostic waveform 303.

[0055] Therefore, by setting the system so that an abnormality is determined to exist when the difference in current value is equal to or greater than a predetermined value (for example, equal to or greater than 10%), the diagnostic unit 38 can clearly determine that an abnormality exists in either the upstream current monitor unit 35 or the downstream current monitor unit 36. As described above, by inputting this determination result as a diagnostic result signal 49 to the feedback control unit 31, the feedback control unit 31 can take appropriate action.

[0056] If the diagnostic unit 38 determines that an abnormality exists in either the upstream current monitor unit 35 or the downstream current monitor unit 36, the diagnostic unit 38 may perform processing to identify which current monitor unit is abnormal. For example, the diagnostic unit 38 can identify which of the upstream current monitor value 46 or the downstream current monitor value 47 is abnormal by comparing the difference between the target current value and the upstream current monitor value 46 and the difference between the target current value and the downstream current monitor value 47 with predetermined values.

[0057] Furthermore, in this embodiment, a diagnosis method for when an abnormality occurs in the downstream current monitor section 36 has been described, but it goes without saying that an abnormality can also be diagnosed in the same way when an abnormality occurs in the upstream current monitor section 35.

[0058] In addition, in this embodiment, an example has been described in which there is an abnormality in either the upstream current monitor unit 35 or the downstream current monitor unit 36, but it is also possible that an abnormality in the output element side will cause the upstream current monitor value 46 or the downstream current monitor value 47 to indicate an abnormal value.

[0059] As can be understood from the above, the present invention focuses on the fact that in a synchronous rectification type load drive circuit 39, the current that flows through a load (e.g., solenoid 21) during the period when the upstream output element 33 is ON and the downstream output element 34 is OFF is equivalent to the current that flows through the load during the period when the upstream output element 33 is OFF and the downstream output element 34 is ON (reflux current).

[0060] When comparing the upstream current monitor value 46 and the downstream current monitor value 47 monitored by the upstream current monitor unit 35 and the downstream current monitor unit 36, if each current monitor unit is normal, the respective current monitor values ​​will be approximately the same. On the other hand, if one of the current monitor units becomes abnormal and cannot properly monitor the current, a discrepancy will be observed between the respective current monitor values. The present invention is based on this mechanism whereby the current monitor values ​​of the upstream current monitor unit 35 and the downstream current monitor unit 36 ​​differ between normal and abnormal conditions.

[0061] As described above, the load driving device (on-board control device 10) according to this embodiment includes a synchronous rectification type load driving circuit (load driving circuit 39) that drives a solenoid, an upstream current monitoring unit (upstream current monitoring unit 35) that detects the current flowing in the upstream output element of the load driving circuit, a downstream current monitoring unit (downstream current monitoring unit 36) that detects the current flowing in the downstream output element of the load driving circuit, and a diagnostic unit (diagnostic unit 38) that compares the current value detected by the upstream current monitoring unit with the current value detected by the downstream current monitoring unit and performs a diagnosis based on the comparison result.

[0062] In this embodiment having the above configuration, for a synchronous rectification type drive load circuit having current monitor units for both the upstream output element and the downstream output element, the diagnostic unit compares the values ​​of the current monitor units to detect an abnormality in the current accuracy of the current monitor units. Therefore, this embodiment makes it possible to diagnose faults in the current monitor units. This improves fault detection capabilities of the load drive device and leads to improved reliability.

[0063] For example, in transmission gear shift control, it is possible to detect in advance gear shift abnormalities (sudden deceleration, engine braking interruption) due to circuit failures in the load drive device. Therefore, this embodiment makes it possible to control the transmission on the safe side (such as by stopping the solenoid current or fixing the gear ratio). For example, this embodiment makes it possible to directly diagnose the validity of the solenoid control current in a load drive device that directly controls a solenoid that adjusts hydraulic pressure, so that if an abnormality in the accuracy of the control current occurs, it is possible to diagnose the abnormality in a short period of time. This makes it possible to take action in a short period of time in response to an abnormality in the transmission system.

[0064] The present invention is not limited to the control of speed changes in a transmission, but is applicable to solenoid current control in general.

[0065] Second Embodiment Next, a diagnostic method for when the monitored current value of the upstream output element 33 or the downstream output element 34 is abnormal in the on-board control device 10 will be described with reference to Fig. 4. Here, the diagnostic method for when the monitored current value of the downstream output element 34 (downstream current monitor unit 36) is abnormal will be described using operating waveforms.

[0066] FIG. 4 is a diagram showing an example of an operating waveform (abnormality diagnosis using a capture value) when the upstream current monitor value 46 of the upstream output element 33 is normal and the downstream current monitor value 47 of the downstream output element 34 is abnormal in the on-board control device according to the second embodiment.

[0067] The downstream current waveform when the downstream current monitor unit 36 ​​is abnormal is referred to as the "downstream current waveform 301," and the signal waveform generated by the current calculation unit 37 when the downstream current monitor unit 36 ​​is abnormal is referred to as the "current calculation unit waveform 302." Furthermore, the signal waveform generated by the diagnosis unit 38 when the downstream current monitor unit 36 ​​is abnormal is referred to as the "diagnosis unit waveform (capture value) 401."

[0068] The diagnostic unit 38 acquires the current value (white circle) of the upstream current waveform (upstream current waveform 202 in Figure 3) at the falling edge of the first PWM signal waveform 201, and the current value (white circle) of the downstream current waveform (downstream current waveform 301 in Figure 3) at the rising edge of the second PWM signal waveform 203.

[0069] In this embodiment, too, the downstream current waveform 301 during an abnormality is assumed to have a smaller current value detected than the downstream current waveform 204 during a normal state. Since the upstream current monitor unit 35 is normal, the upstream current waveform 202 indicates a normal value.

[0070] The normal upstream current waveform 202 and the abnormal downstream current waveform 301 are combined in the current calculation unit 37, and the combined waveform at this time is shown as the current calculation waveform 302. The abnormal current calculation waveform 302 is a waveform different from the normal current calculation waveform 205. The current value calculated from this waveform is small compared to the actual current flowing through the solenoid 21.

[0071] However, if an incorrect current value is input to the feedback control unit 31 as the current monitor value 48, the feedback control unit 31 will perform control based on the incorrect current monitor value 48. This may cause a risk of malfunction in the vehicle system in which the solenoid 21 is used.

[0072] Here, a normal upstream current waveform 202 and a downstream current waveform 301 with an abnormal downstream current monitor value 47 are input to the diagnostic unit 38. The currents of the upstream output element 33 and the downstream output element 34 are alternately detected by the upstream current monitor unit 35 and the downstream current monitor unit 36. The diagnostic unit 38 compares the current value detected by the upstream current monitor unit 35 (upstream current monitor value 46) with the current value detected by the downstream current monitor unit 36 ​​(downstream current monitor value 47) before and after the current detection by the upstream current monitor unit 35 is switched to the current detection by the downstream current monitor unit 36.

[0073] 4, when the diagnostic unit 38 compares the normal current value of the upstream current waveform 202 at the falling edge of the first PWM signal waveform 201 with the current value of the downstream current waveform 301 at the rising edge of the second PWM signal waveform 203, a large deviation occurs, as shown in the diagnostic unit waveform 401. That is, in the diagnostic unit waveform 401, the captured value of the upstream current waveform 202 at the falling edge of the first PWM signal waveform 201 differs from the captured value of the downstream current waveform 301 at the rising edge of the second PWM signal waveform 203.

[0074] Therefore, by setting the diagnostic unit 38 to determine that an abnormality has occurred when the difference in the current values ​​is equal to or greater than a predetermined value (for example, equal to or greater than 10%), the diagnostic unit 38 can clearly determine that an abnormality has occurred in the downstream current monitor unit 36. As described above, by inputting this determination result as a diagnostic result signal 49 to the feedback control unit 31, the feedback control unit 31 can take appropriate action.

[0075] In this embodiment, the diagnosis method when an abnormality occurs in the downstream current monitor section 36 has been described, but it goes without saying that an abnormality can also be diagnosed in the same way when an abnormality occurs in the upstream current monitor section 35.

[0076] Third Embodiment Next, an on-board control device according to a third embodiment will be described with reference to Fig. 5 and Fig. 6. The on-board control device according to the third embodiment is characterized in that the target current instruction unit 30, the feedback control unit 31, and the diagnosis unit 38 in the on-board control device 10 shown in Fig. 1 are realized by a microcomputer.

[0077] [Configuration and Operation of On-Vehicle Control Device] Fig. 5 is a diagram showing an example of the internal configuration (diagnosis configuration using a microcomputer) of an on-vehicle control device according to the third embodiment. The on-vehicle control device 10A according to this embodiment differs from the on-vehicle control device 10 of the first embodiment (Fig. 1) in that the functions of the target current instruction unit 30, the feedback control unit 31, and the diagnosis unit 38 are implemented in a microcomputer 500 equipped with a processor and memory. The configuration of this embodiment can also be applied to the second embodiment.

[0078] Next, the operation of the on-board control device 10A will be described. The actual operation of the on-board control device 10A is similar to that of the on-board control device 10 described above with reference to FIG. 1 . However, by implementing the functions of the target current instruction unit 30, feedback control unit 31, and diagnosis unit 38, which involve advanced arithmetic processing, in a microcomputer 500, it becomes possible to configure each control by software. This makes it possible to flexibly set the conditions for abnormality diagnosis when either or both of the upstream current monitor unit 35 and the downstream current monitor unit 36 ​​fail (the predetermined value "10%" in the above example) for the on-board system to which the solenoid 21 is applied.

[0079] Furthermore, as a fail-safe operation after the abnormality diagnosis is performed, the feedback control unit 31 controls the solenoid 21, which is the direct control target, to operate in a predetermined manner that is highly safe.

[0080] Furthermore, as a process after the abnormality diagnosis, the feedback control unit 31 may perform control to record in memory, for example, information on the in-vehicle system side when it is diagnosed that an abnormality has occurred in the upstream current monitor unit 35 or the downstream current monitor unit 36. The information on the in-vehicle system side is, for example, the command current value or current monitor value of the solenoid 21, other signal information acquired by the in-vehicle control device 10A, etc. Furthermore, when the abnormality diagnosis is performed, the feedback control unit 31 may perform control to notify the vehicle occupant of the abnormality by means of a lamp on the instrument panel or a beep sound.

[0081] Here, the hardware configuration of the microcomputer 500 included in the on-board control device 10A will be described with reference to FIG.

[0082] [Hardware Configuration of Microcomputer] Fig. 6 is a block diagram showing an example of the hardware configuration of the microcomputer 500 included in the on-board controller 10A. A computer 600 shown in Fig. 6 is an example of hardware used as a computer. The on-board controller 10A realizes control of the on-board system performed by the respective functional blocks shown in Fig. 5 working together, by the computer 600 (computer) executing a program.

[0083] The computer 600 includes a CPU (Central Processing Unit) 601, a ROM (Read Only Memory) 602, and a RAM (Random Access Memory) 603, all connected to a system bus. The ROM and RAM are examples of memory. The computer 600 also includes a non-volatile storage 604 and an input / output interface 605.

[0084] The CPU 601 reads out program code of software that realizes each function according to this embodiment from the ROM 602, loads it into the RAM 603, and executes it. Variables, parameters, etc. that are generated during the calculation processing of the CPU 601 are temporarily written to the RAM 603, and these variables, parameters, etc. are read out as appropriate by the CPU 601. The functions of each part of the on-board control device 10 are realized by the CPU 601 executing the program code read out from the ROM 602. However, another processor such as an MPU (Micro Processing Unit) may be used instead of the CPU 601.

[0085] The nonvolatile storage 604 is an example of a recording medium, and is capable of storing data used by a program, data obtained by executing a program, etc. The nonvolatile storage 604 may also store an operating system (OS) or a program executed by the CPU 601. The nonvolatile storage 604 may be a hard disk drive (HDD), a solid state drive (SSD), an optical or magnetic disk medium, a semiconductor memory card, or the like.

[0086] The input / output interface 605 is an input / output device that controls communication between the microcomputer 500 and each unit in the on-board control device 10A. Note that an input / output device that complies with a communication standard such as CAN (Controller Area Network) may be used as the input / output interface 605. In this case, the input / output interface 605 can transmit and receive various types of data to and from external devices (other on-board control devices, sensors, etc.) via a communication network such as CAN or a dedicated line, etc.

[0087] The on-board control device 10A may be connected to a display device and an input device (not shown). For example, a lamp on an instrument panel is an example of a display device. The on-board control device 10A may also be connected to a speaker that outputs sounds such as beeps.

[0088] <Fourth embodiment> Next, an on-board control device according to a fourth embodiment will be described with reference to Fig. 7. The on-board control device according to the fourth embodiment is characterized in that the feedback control unit 31 and the diagnosis unit 38 in the on-board control device 10 shown in Fig. 1 are implemented by a hardware logic circuit configuration.

[0089] [Configuration and Operation of In-Vehicle Control Device] Fig. 7 is a diagram showing an example of the internal configuration of an in-vehicle control device according to the fourth embodiment (a diagnostic configuration using a hardware logic circuit). The in-vehicle control device 10B according to this embodiment differs from the in-vehicle control device 10 (Fig. 1) according to the first embodiment in that the feedback control unit 31 and the diagnostic unit 38 are implemented by a hardware logic circuit configuration 700. The configuration of this embodiment can also be applied to the second embodiment.

[0090] Next, the operation of the on-board control device 10B will be described. The actual operation of the on-board control device 10B is similar to that of the on-board control device 10 described above with reference to Fig. 1. In addition to the functions of the feedback control unit 31 and the diagnosis unit 38, the function of the target current instruction unit 30 can also be realized by a hardware logic circuit configuration 700.

[0091] In cases where the cost of the on-board control device 10B is prioritized over advanced control of the solenoid 21, it is also effective to realize the functions of the feedback control unit 31 and the diagnosis unit 38 (and the target current indication unit 30) using a hardware logic circuit configuration 700, as in this embodiment.

[0092] The present invention is not limited to the above-described embodiments, and various other applications and modifications are possible without departing from the spirit of the present invention as set forth in the claims. For example, the above-described embodiments have been described in detail and specifically to clearly explain the present invention, and are not necessarily limited to those including all of the components described. Furthermore, it is also possible to add, replace, or delete other components to or from part of the configuration of each embodiment.

[0093] Furthermore, some or all of the above-described configurations, functions, processing units, etc. may be implemented in hardware, for example, by designing them as integrated circuits, etc. As the hardware, a broad processor device such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit) may be used.

[0094] In the above-described embodiment, the control lines and information lines are those that are considered necessary for the explanation, and not all control lines and information lines in the product are necessarily shown. In reality, it can be considered that almost all components are connected to each other.

[0095] 10, 10A, 10B... In-vehicle control device, 11... Power supply connector, 12... Solenoid connector, 20... Power supply, 21... Solenoid, 30... Target current instruction unit, 31... Feedback control unit, 32... Driver control unit, 33... Upstream output element, 34... Downstream output element, 35... Upstream current monitor unit, 36... Downstream current monitor unit, 37... Current calculation unit, 38... Diagnosis unit, 39... Load drive circuit, 40... PWM signal, 41... First PWM signal, 42... Second PWM signal, 43... Upstream current, 44... Downstream current, 45... Solenoid Id current, 46...upstream current monitor value, 47...downstream current monitor value, 48...current monitor value, 49...diagnosis result signal, 201...first PWM signal waveform, 202...upstream current waveform, 203...second PWM signal waveform, 204...downstream current waveform, 205...current calculation unit waveform, 206...diagnosis unit waveform, 301...downstream current waveform, 302...current calculation unit waveform, 303...diagnosis unit waveform (average value), 401...diagnosis unit waveform (capture value), 500...microcomputer, 600...computer, 700...hardware logic circuit configuration

Claims

1. A load driving device comprising: a synchronous rectification type load driving circuit that drives a solenoid; an upstream current monitoring unit that detects a current flowing in an upstream output element of the load driving circuit; a downstream current monitoring unit that detects a current flowing in a downstream output element of the load driving circuit; and a diagnostic unit that compares the current value detected by the upstream current monitoring unit with the current value detected by the downstream current monitoring unit and performs a diagnosis based on the comparison result.

2. The load driving device according to claim 1, wherein the diagnostic section compares an average value of the current value detected by the upstream current monitor section with an average value of the current value detected by the downstream current monitor section.

3. A load driving device as described in claim 1, wherein the currents of the upstream output element and the downstream output element are alternately detected by the upstream current monitoring unit and the downstream current monitoring unit, and the diagnosis unit compares the current value detected by the upstream current monitoring unit with the current value detected by the downstream current monitoring unit before and after the current detection by the upstream current monitoring unit and the current detection by the downstream current monitoring unit are switched.

4. The load driving device according to claim 2, wherein the diagnostic section is a function implemented in a microcomputer.

5. The load driving device according to claim 3, wherein the diagnostic section is a function implemented in a microcomputer.

6. The load driving device according to claim 2, wherein the diagnostic unit is configured with a hardware logic circuit.

7. The load driving device according to claim 3, wherein the diagnostic unit is configured with a hardware logic circuit.

Images