JP6655574B2 - Load drive - Google Patents

Description

  The present invention relates to a load driving device that controls a load driving by providing a high-side switch and a low-side switch at both ends of a load, and particularly to a diagnostic method thereof.

  2. Description of the Related Art Conventionally, as disclosed in, for example, Patent Document 1, there is known a device that includes a high-side switch and a low-side switch at both ends of a load and drives the load.

  Patent Literature 1 discloses an example of an engine start control device as a load driving device. In this example, a current monitor, a voltage monitor, a low voltage source and a transistor as a switching means are provided on the high side of the starter relay which is a load, and a current monitor, a voltage monitor, a low voltage source and a switching device are similarly provided on the low side. It has a transistor as a means.

  The voltage of the two current paths when both of the two switching means are off, the voltage of the switching means current path on the off-state side and the on-state side when only one of the two switching means is turned on. And the currents flowing through the two switching means when both switching means are turned on. Alternatively, the voltage of the two current paths when the two switching means are both turned off, the voltage of the low-side switching means current path when only the high-side switching means is turned on, and the high-side switching means The current flowing, the voltage of the high side switching means current path when only the low side switching means is turned on, and the current flowing to the low side switching means are detected.

  Depending on the combination of these detection results, the high-side power supply short-circuit fault is a fault in which the high-side output terminal is short-circuited to the voltage of the high-potential terminal of the power supply, and the fault is that the low-side output terminal is short-circuited to the voltage of the high-potential terminal of the power supply. A low-side power short-circuit failure, a high-side ground short-circuit failure in which the high-side output terminal is short-circuited to the voltage of the low-potential terminal of the power supply, and a low-side failure in which the low-side output terminal is short-circuited to the voltage of the low-potential terminal of the power supply. Ground short fault, open fault that is a fault in which the electrical connection between at least one of the two output terminals and the load is broken, and two output terminals are electrically connected without the load The short-circuit failure between terminals, which is a failure, is detected separately.

JP 2012-182949 A

  In the above-described engine start control device, the high-side power short-circuit failure, the low-side power short-circuit failure, the high-side ground short-circuit failure, the low-side ground short-circuit failure, the open failure, and the short-circuit between the terminals can be distinguished and detected. In addition, a current monitor, a voltage monitor, and a low voltage source are required on the high side, and a current monitor, a voltage monitor, and a low voltage source are similarly required on the low side. This means that a large number of circuit components or a dedicated LSI is required for realization.

  In addition, in order to perform the diagnosis, a combination of three types of switching means on / off is required. That is, when the two switching means are both off, when only one of the two switching means is on, when the two switching means are both on, three types of combinations, or when the two switching means are both Three types of combinations are required: off, when only the high-side switching means is on, and when only the low-side switching means is on.

  Further, in the engine start control device, it is assumed that the starter relay is turned on and off, and no particular consideration is given to controlling the current flowing to the load or detecting the current with high accuracy.

  Accordingly, the present invention provides a voltage monitor and a low-voltage monitor to realize fault diagnosis of these high-side power supply short-circuit faults, low-side power short-circuit faults, high-side ground short-circuit faults, low-side ground short-circuit faults, open faults, and short-circuits between terminals. An object of the present invention is to provide a load driving device that does not require a voltage source and does not require a combination of ON and OFF of a switching unit.

  According to the load driving device according to claim 1, as a high-side output terminal connected to one end of the load, a low-side output terminal connected to the other end of the load, and as switching means for switching whether to energize the load. High-side switching means for energizing or interrupting the high potential side of the power supply and the high-side output terminal; low-side switching means for energizing or interrupting the low potential side of the power supply and the low-side output terminal; High-side current detection means for detecting a current flowing through the side switching means, and a low-side current detection means for detecting a current flowing through the low-side switching means, when the high-side switching means and the low-side switching means are on, A current value detected by the high-side current detection means; Wherein configured to perform failure diagnosis based on the current value detected by the low-side current detection means.

  Therefore, the high-side voltage monitor and the low-voltage source, and the low-side voltage monitor and the low-voltage source are not required, and the two high-side A power short-circuit fault, in which at least one of the output terminals is short-circuited to the voltage of the high-potential terminal of the power supply, or a high-side ground short, a fault in which the high-side output terminal is short-circuited to the voltage of the low-potential terminal of the power supply. Failure, a low-side ground short-circuit failure in which the low-side output terminal is short-circuited to the voltage of the low-potential-side terminal of the power supply, and at least one of the two output terminals is electrically disconnected from the load. Open fault, and a fault in which the two output terminals are electrically connected without passing through the load. It is possible to detect and distinguish between the inter-terminal short-circuit failure that.

  According to the load driving device of the second aspect, the current detection accuracy and the range of the low-side current detection means are different from the current detection accuracy and the range of the high-side current detection means.

  Therefore, while ensuring the detection accuracy in a region where the current flowing through the load is small and precise control is required, the detection accuracy is not so much required, but the method of detecting a large current (for example, the use as overcurrent protection), Can be handled.

  The load driving device according to claim 3, further comprising control means for obtaining a desired load driving current waveform by turning on / off the high-side switching means while the low-side switching means is on, and detecting the low-side current. The current detection accuracy of the means is higher than the current detection accuracy of the high-side current detection means, and the current detection range of the high-side current detection means is wider than the current detection range of the low-side current detection means. .

  Therefore, it is possible to accurately detect the current that continuously flows through the load including the current during the period when the low-side switching device is on and the high-side switching device is off, that is, during the period when the return current flows through the load.

According to the first embodiment of the present invention, a high-pressure fuel pump (HPFP) circuit is provided that includes a high-side current detection unit and a low-side current detection unit, and performs a failure diagnosis based on a value of a detection current obtained from the high-side current detection unit. FIG. 2 is a block diagram of an ECU (engine control unit). According to the second embodiment of the present invention, there are provided a high-side current detecting means and a low-side current detecting means having a gain larger than that of the low side, and a fault diagnosis is performed based on a detected current value obtained from these means. FIG. 2 is a block diagram of an ECU including an HPFP circuit. 5 is a waveform showing a high-side switching control signal, a low-side switching control signal, and a current flowing through a load according to the first embodiment of the present invention. The high-side switching control signal, the low-side switching control signal, the current flowing through the load, the current detected by the high-side current detecting means, and the current detected by the low-side current detecting means according to the second embodiment of the present invention. It is a waveform which shows a current. FIG. 7 is a graph showing the values of the current detected by the high-side current detection unit and the current detected by the low-side current detection unit, which are captured by an ADC (Analog Digital Converter) of the microcomputer according to the second embodiment of the present invention. . 4 is a diagnosis table for separating and detecting each fault state from the current detected by the high-side current detection means and the current detected by the low-side current detection means according to the first embodiment of the present invention. 9 is a diagnosis table according to the second embodiment of the present invention for separating and detecting each fault state from the current detected by the high-side current detection unit and the current detected by the low-side current detection unit. 9 is a flowchart illustrating a diagnostic procedure according to the second embodiment of the present invention.

(First embodiment)
Hereinafter, the first embodiment will be described with reference to FIGS. 1, 3, and 6. FIG.

  FIG. 1 is a block diagram showing an HPFP drive circuit in an ECU and a circuit portion for performing a failure diagnosis of the HPFP drive circuit. A load 500 such as a solenoid constituting the HPFP is connected to the ECU 100 via a high-side output terminal 110 and a low-side output terminal 120. On the high side, a high side switching means 400 such as an FET is connected to a VB power supply 200 supplied from a battery, an alternator, or the like, and is controlled by an output terminal DO1 of the microcomputer 300. Then, between the high-side switching means 400 and the high-side output terminal 110, a high-side current detection means 410 including a current detection resistor and an OP amplifier is connected. The output of the high-side current detection means 410 is connected to the AD1 input terminal of the microcomputer 300, and is taken in as a digital value by the microcomputer built-in AD converter 310.

  A low-side switching means 430 such as an FET is connected to the low-side output terminal 120, and is controlled by the output terminal DO2 of the microcomputer 300. Between the low-side switching means 430 and the ground, a low-side current detecting means 440 including a current detecting resistor and an OP amplifier is connected. The output of the low-side current detection means 440 is connected to the AD2 input terminal of the microcomputer 300, and is taken in as a digital value similarly to the high-side.

  In this embodiment, the load 500 is driven with a current profile indicated by I (Load) in FIG. The current profile includes a Pull_In phase and a Peak phase, which are phases for driving the solenoid, and a Hold phase for holding. In order to realize this current profile, in the present embodiment, the high side switching means 400 is controlled as V (DO1), and the low side switching means 430 is controlled as V (DO2). In the Pull_In phase, the high-side switching means 400 and the low-side switching means 430 are turned on until a desired peak current is reached. In the Peak phase, only the high-side switching means 400 is turned on and off at such a rate as to maintain the peak current. Similarly, in the Hold phase, only the high-side switching means 400 is turned on and off at such a ratio that a desired hold current can be maintained. In order to obtain a desired load drive current by turning the high side on and off with the low side turned on, the free wheel diode 460 is connected between the high side output terminal 110 and the ground.

  Next, according to the current values obtained from the high-side current detection means and the low-side current detection means, how to detect the power supply short-circuit failure, the high-side ground short-circuit failure, the low-side ground short-circuit failure, the open failure, and the short-circuit between terminals is detected. This will be described with reference to FIG.

  In this embodiment, the load 500 is driven with a current profile in which the peak current is 7 to 8 A and the hold current is 2 to 3 A. Further, when a current of 10 A or more flows, it has a function of stopping the high-side switching means 400 and the low-side switching means 430 as overcurrent protection for preventing destruction or deterioration of a circuit or a load.

  Immediately after the start of the Pull_in phase, the failure diagnosis is not performed because the current is small, and when the high-side switching means 410 and the low-side switching means 430 are both turned on from a known timing at which a current of 1 A or more is known to flow. Diagnosis is performed at 5 ms intervals. The start timing of the diagnosis is not limited to the HPFP circuit but can be applied to various uses by designing it according to the circuit or load to be applied. Also, the interval of diagnosis is not limited to the interval of 5 milliseconds, and it goes without saying that the interval can be arbitrarily designed according to the importance of protection of a circuit or a load to be applied and the processing capability of a microcomputer.

  Hereinafter, the criterion for each combination of the high side detection current and the low side detection current will be described.

  When both the high-side detection current and the low-side detection current are 1 A or more and the overcurrent protection is not activated, it is determined that a normal state is set.

  If the high-side detection current is less than 0.5 A and the low-side detection current is 10 A or more, it is determined that a power supply short circuit has occurred. When the high-side output terminal 110 or the low-side output terminal 120 is short-circuited, the VB power supply 200 and the high-side output terminal 110 have substantially the same potential. This is because the current flowing through the low-side current detection means 440 continues to increase while the switching means 430 is on, and reaches 10 A or more where overcurrent protection works on the low side.

  When the high-side detection current is 10 A or more and the low-side detection current is less than 0.5 A, it is determined that a high-side ground short-circuit fault has occurred. When the high-side output terminal 110 is short-circuited to the ground, when the high-side switching means 400 is turned on, the inductive load is not connected and reaches 10 A or more, while the low-side output terminal 120 is at the ground potential. This is because no current flows through the low-side current detection means 440.

  If the high-side detection current is 1 A or more and the low-side detection current is less than 0.5 A, it is determined that a low-side ground short-circuit fault has occurred. When the low-side output terminal 120 is short-circuited to the ground, a current flows to the ground via the inductive load when the high-side switching means 400 is turned on. This is because no current flows through the detection means 440.

  If the high-side detection current is less than 0.5 A and the low-side detection current is less than 0.5 A, it is determined that an open failure has occurred. This is because there is no current flow path even when the high-side switching means 400 is turned on or the low-side switching means 430 is turned on.

  If the high-side detection current is 10 A or more and the low-side detection current is 10 A or more, it is determined that a short-circuit between terminals has occurred. When a short circuit occurs between the terminals, the VB power supply 200 is connected to the ground through the high-side switching means 400, the high-side current detection means 410, the low-side switching means 430, and the low-side current detection means 440 without an inductive load. This is because the same large current flows in the high side and the low side because of the connection.

  As described above, the combination of the high-side detection current and the low-side detection current makes it possible to separately diagnose a power supply short-circuit fault, a high-side ground short-circuit fault, a low-side ground short-circuit fault, an open fault, and a short-circuit between terminals.

That is, in the present embodiment, whether the high side is smaller than the first predetermined value, whether it is larger than the second predetermined value, whether the low side is smaller than the third predetermined value, It is determined whether or not the fault is larger than the threshold, and the fault is distinguished based on the condition of the combination. In the present embodiment, when the detected current value of the high-side current detecting means is smaller than the first predetermined value and the detected current value of the low-side current detecting means is larger than the fourth predetermined value, it is determined that the power supply is short-circuited, and If the detected current value of the side current detecting means is larger than the second predetermined value and the detected current value of the low side current detecting means is smaller than the third predetermined value, it is determined that a high side ground short circuit has occurred, and the high side current detecting means is detected. If the detected current value is larger than the first predetermined value and the detected current value of the low-side current detecting means is smaller than the third predetermined value, it is determined that a low-side ground short-circuit fault has occurred and the detected current value of the high-side current detecting means is If the current value is smaller than the first predetermined value and the detected current value of the low-side current detecting means is smaller than the third predetermined value, it is determined that an open failure has occurred, and the high-side current detecting means is determined. Of the detected current value is greater than the second predetermined value, when the detected current value of the low-side current detection means is larger than a fourth predetermined value, by determining the inter-terminal short-circuit failure, requires a voltage monitor or the low-voltage source However, it is possible to provide a load driving device that does not require a combination of ON and OFF of the switching means.

  In the present embodiment, an example in which the first predetermined value = the third predetermined value <the second predetermined value = the fourth predetermined value has been described.

(Second embodiment)
Second Embodiment A second embodiment will be described with reference to FIGS. 2, 4, 5, 7, and 8. FIG. The description of the same configuration as the first embodiment is omitted.

  FIG. 2 is a block diagram showing an HPFP drive circuit in the ECU and a circuit portion for performing a failure diagnosis of the same as in the first embodiment. The difference from the first embodiment lies in that the high-side current detection means 410 is composed of a high-side current detection resistor 411 of 20 mΩ and a high-side current detection operational amplifier 412 having a gain of 20 times. The low-side current detection means 440 comprises a low-side current detection resistor 441 of 20 mΩ and a low-side current detection operational amplifier 442 having a gain of 10 times.

  In this embodiment, the microcomputer built-in AD converter 310 has a resolution of 10 bits and operates on a 5 V power supply not specified. Therefore, the high-side current detecting means can detect a range of 0A to 12.5A with a resolution of 12.2 mA per bit. On the other hand, the low-side current detecting means can detect a range of 0 A to 6.25 A with a higher resolution of 6.1 mA per bit. FIG. 5 shows this state. In the present embodiment, a 10-bit AD converter is described as an example, but an AD converter having an arbitrary resolution can also be used.

  FIG. 4 shows the current I (High) observed by the high-side current detection unit 410 and the current I (High) observed by the low-side current detection unit 440 when the current indicated by I (Load) flows through the load 500. (Low). The current I (High) observed by the high-side current detection means 410 can be detected only when the high-side switching means 400 indicated by V (DO1) is on, and is therefore observed as a comb-shaped waveform. Although the current is largely different from the current flowing through the load 500, the current can be detected up to a region of 10 A or more where overcurrent protection is required. On the other hand, the current I (Low) observed by the low-side current detection unit 440 is interrupted similarly to the current flowing through the load 500 because the current can be detected when the low-side switching unit 430 indicated by V (DO2) is on. The waveform can be observed without the need. By making the current detection accuracy of the low-side current detection means 440 high, the current flowing through the load 500 can be detected continuously and with high accuracy in a current region where accuracy is required.

  Next, in the second embodiment, according to the current values obtained from the high-side current detecting means and the low-side current detecting means according to the diagnosis table of FIG. A procedure for detecting a short fault, an open fault, and a short fault between terminals while distinguishing the short fault will be described with reference to the flowchart of FIG. Also in this embodiment, similarly to the first embodiment, the load 500 is driven with a current profile having a peak current of 7 to 8 A and a hold current of 2 to 3 A. It has a function of stopping the high-side switching means 400 and the low-side switching means 430 as overcurrent protection for preventing destruction or deterioration.

  Diagnosis starts at the timing when both the high-side switching means and the low-side switching means are on and a current of 1 A or more normally flows (F01). The high-side detection current and the low-side detection current are read (F02), and it is determined whether the high-side detection current is 10 A or more (F03). If the current is 10 A or more, the high-side switching means 400 and the low-side switching means 430 are immediately stopped as overcurrent protection (F04), and then it is determined whether the low-side detection current exceeds 6A (F05). If it exceeds 6A, it is reported that a short-circuit has occurred between the terminals (F08), and the diagnosis is terminated (F18). On the other hand, if the current is 6 A or less, the low-side detection current should be less than 0.25 A (F06), a high-side ground short fault is reported (F07), and the diagnosis is terminated (F18). Returning to F03, when the high side detection current is less than 10A, it is determined whether the low side detection current continues to exceed 6A (F09). If it exceeds 6 A, it is determined whether the high-side detection current is 0.5 A or less (F10). If it is 0.5 A or less, the high-side switching means 400 and the low-side switching means 430 are stopped as overcurrent protection (F11). ), A power short-circuit failure is reported (F12), and the diagnosis is terminated (F18). On the other hand, if it exceeds 0.5 A, the normal operation (F14) is performed, and the diagnosis is terminated without doing anything (F18). Returning to F09, if the low-side detection current is 6 A or less, it is determined whether the low-side detection current is less than 0.25 A (F13). If it is 0.25 A or more, the diagnosis is terminated without any operation because the normal operation (F14) (F18). If it is less than 0.25 A, it is further determined whether the high-side detection current is less than 0.5 A (F15). If it is less than 0.5 A, an open failure is reported (F17), and the diagnosis is terminated (F18). On the other hand, if it is 0.5 A or more, it is reported that a low-side ground short fault has occurred (F16), and the diagnosis is terminated (F18).

  In this manner, based on the diagnosis table shown in FIG. 7, it is possible to separate and diagnose a power supply short-circuit failure, a high-side ground short-circuit failure, a low-side ground short-circuit failure, an open failure, and a short-circuit between terminals.

  In the first and second embodiments, a configuration in which the high side is continuously turned on and off and the low side is continuously turned on is described as an example. However, it is conversely applicable to a configuration in which the low side is continuously turned on and the high side is continuously turned on. Needless to say. Further, the method of detecting the current is not limited to the combination of the shunt resistor and the operational amplifier.

  100: ECU, 110: high side output terminal, 120: low side output terminal, 200: VB power supply, 300: microcomputer, 310: microcomputer built-in AD converter, 400: high side switching means, 410: high side current detection means, 411: High-side current detection resistor, 412: high-side current detection operational amplifier, 430: low-side switching means, 440: low-side current detection means, 441: low-side current detection resistance, 442: low-side current detection operational amplifier, 460: freewheeling diode, 500: load

Claims (9)

A high-side output terminal connected to one end of the load,
A low-side output terminal connected to the other end of the load,
High-side switching means for energizing or shutting off the high-potential side of the power supply and the high-side output terminal, as switching means for switching whether or not to energize the load;
Low-side switching means for energizing or interrupting the low-potential side of the power supply and the low-side output terminal,
High-side current detection means for detecting a current flowing through the high-side switching means,
Low-side current detection means for detecting a current flowing through the low-side switching means,
With
When the high-side switching means and the low-side switching means are on, at least one of the two output terminals is connected to the power supply by a current value detected by the high-side current detection means and a current detection value by the low-side current detection means. A power short-circuit fault, which is a fault shorted to the voltage of the high-potential side terminal; a high-side ground short fault, which is a fault in which the high-side output terminal is short-circuited to the voltage of the low-potential side terminal of the power source; A low-side ground short-circuit fault, which is a fault short-circuited to the voltage of the low-potential-side terminal, an open fault, in which at least one of the two output terminals is disconnected from the load. Failure in which the two output terminals are electrically connected without passing through the load To detect and distinguish between the short-circuit failure between a certain terminal,
If the detected current value of the high-side current detecting means is smaller than a first predetermined value, and the detected current value of the low-side current detecting means is larger than a fourth predetermined value, it is determined that the power supply short-circuit failure,
If the detected current value of the high-side current detecting means is larger than a second predetermined value, and the detected current value of the low-side current detecting means is smaller than a third predetermined value, it is determined that the high-side ground short-circuit failure,
If the detected current value of the high-side current detecting means is larger than a first predetermined value, and the detected current value of the low-side current detecting means is smaller than a third predetermined value, it is determined that the low-side ground short-circuit failure,
If the detected current value of the high-side current detecting means is smaller than a first predetermined value and the detected current value of the low-side current detecting means is smaller than a third predetermined value, it is determined that the open failure,
When the detected current value of the high-side current detecting means is larger than a second predetermined value and the detected current value of the low-side current detecting means is larger than a fourth predetermined value, it is determined that the inter-terminal short-circuit fault has occurred. Load drive device. 2. The load driving device according to claim 1 , wherein the fourth predetermined value and the second predetermined value satisfy a relationship that is greater than the third predetermined value and the first predetermined value. 3. The load drive device according to claim 2 , wherein a relationship of the first predetermined value = the third predetermined value and the second predetermined value = the fourth predetermined value is satisfied. 3. The load driving device according to claim 2 , wherein a relationship of the first predetermined value ≠ the third predetermined value, the second predetermined value ≠ the fourth predetermined value is satisfied. Before SL low-side current and the current detection accuracy and range of detection means, the load driving device according current detection accuracy and range of the high-side current detection means in different claims 1. Control means for obtaining a desired load drive current waveform by turning on and off the high-side switching means while turning on the low-side switching means,
The current detection accuracy of the low-side current detection means is higher than the current detection accuracy of the high-side current detection means, and the current detection range of the high-side current detection means is wider than the current detection range of the low-side current detection means. Item 6. The load driving device according to Item 5 . The high-side switch means is controlled to be turned on and off so as to be held at a hold current after being held at a peak current,
The second predetermined value is equal to or greater than a peak current,
The fourth predetermined value is not less than a hold current and not more than a peak current,
Wherein the first, load driving device according to any one of the third of claims 1 to 6 predetermined value is less than the hold current. 8. The load driving device according to claim 7 , wherein when the detected current value of the high-side current detecting means is larger than a second predetermined value, the driver for driving the high-side switching means and the driver for driving the low-side switching means are stopped. If the detected current value of the high-side current detecting means is smaller than a first predetermined value and the detected current value of the low-side current detecting means is larger than a fourth predetermined value, the driver for driving the high-side switching means and the low-side load driving device according to claim 7 or 8 stops driver for driving the switching means.

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