Method for monitoring a short-circuit switching process in a circuit of a control device

Abstract

The invention relates to a method for monitoring short circuit switching processes of a circuit (120) of a control device (100), in particular an output stage circuit (120), in which information about the control device (100) is detected (202), an evaluation is made (203) as to whether a short circuit switching process is present and the circuit (120) performs a switch-on process during a short circuit, and if in the course of the evaluation a short circuit switching process is detected, a counter reading is updated (204), and the counter reading characterizes the number of short circuit switching processes performed over the lifetime of the circuit (120).

Description

[Technical Field]

[0001] The invention relates to a method for monitoring short-circuit switching processes in circuits of a control device, in particular in a vehicle, and to a computing device for carrying out the method. [Background technology]

[0002] The output stage or output stage circuit of a control device, for example in an (automotive) vehicle, represents the electronic final stage of a power amplifier before the amplified signal is applied to a load. For example, an output stage circuit may be provided in an engine control device to provide the power required to drive and control an actuator. In the control device, each output stage circuit may be driven and controlled by a microcontroller using a corresponding drive control signal.

[0003] To ensure the (operational) safety of the control device, the output stage circuit generally needs to be robust enough to withstand at least a certain minimum number of (ON) switching processes in the event of a short circuit, i.e., a short circuit to the battery or earth. However, especially in the case of pulse width modulation control, excessive such short-circuit switching processes can damage or even destroy the output stage and thus the entire control device. Summary of the Invention [Means for solving the problem]

[0004] Against this background, a method for monitoring short-circuit switching processes in a circuit of a control device and a computing device for carrying out the method are proposed, which have the features of the independent claims. Advantageous embodiments are the subject of the dependent claims and the following description.

[0005] During the method, current information about the control device is detected and evaluated as to whether a short-circuit switching process exists, i.e., whether the circuit performs a switch-on process during a short circuit (i.e., no load). If during the evaluation, it is detected that a short-circuit switching process exists, a counter or counter reading is updated or incremented to characterize or represent the number of short-circuit switching processes performed over the life of the circuit.

[0006] By detecting and evaluating the information of the control device, it is advantageously possible to detect whether a short-circuit switching process is currently taking place while the control device is in operation, so that the counter readings are continuously updated during use if a new short-circuit switching process is detected.

[0007] Based on the counter readings, measures can be taken to protect the output stage circuitry or to correct errors, for example. The counter readings can also be used to infer the magnitude of the risk of damage or destruction of the output stage, and if the counter readings are very high, for example approaching a predetermined number of allowed (ON) switching processes in the event of a short circuit, the operation of the output stage can be limited or affected.

[0008] The counter readings can advantageously be read in the workshop, for example, to facilitate troubleshooting and repairs. Also, if the output stage or control unit is damaged or destroyed, the counter readings can be useful in the subsequent investigation of the cause. Based on the counter readings, it can be particularly advantageous to check whether a warranty claim is valid. For example, based on the counter readings, it can be determined whether an (end) customer has ignored a warning, such as an activated engine check light, for a long period of time, which can lead to a reduction or elimination of warranty service by the (control unit) manufacturer.

[0009] The information about the control device characterizes, in particular, the current operation of the control device, in particular the current signal from the control device for controlling the output stage circuit, and in particular the current error or error message of the control device. Based on this information, it is particularly advantageous to determine whether the circuit is currently being controlled or whether a short circuit is currently present in the control device. For example, various means are known and some have been specified for detecting a short circuit in the output stage of a vehicle control device. For example, the detected measured values ​​can be evaluated. For example, it can be checked whether the current flowing through the output stage circuit exceeds a permissible limit value. Furthermore, error diagnosis or a diagnostic function of the control device can be used to detect the error state.

[0010] Advantageously, a prioritization of short-circuit switching processes that are performed, are scheduled to be performed, or may be performed during a given diagnostic interval, in particular a current diagnostic interval, is performed depending on the counter reading or the current value of the counter reading. For example, these individual diagnostic intervals can respectively correspond to driving cycles of a (motor vehicle). Preferably, short-circuit switching processes performed in the course of an error diagnosis or error detection are prioritized. Based on such switching processes for error diagnosis, it is possible to check or detect, in particular, whether a short circuit still exists or whether the control device will function without a short circuit again after recovery without an error. Using this priority, it is advantageous to adjust or set the frequency with which each diagnostic interval is checked for whether a short circuit still exists. The higher the assigned priority, the more frequently error diagnosis is performed per diagnostic interval. In particular, to avoid unnecessary many short-circuit switching processes and damage or destruction of the output stage circuit, the number of error diagnosis processes performed per diagnostic interval can always be reduced as the circuit ages.

[0011] For example, if the counter reading is low, particularly reflecting the early use of the output stage, the likelihood of recovery or correction of the short circuit is higher at the beginning of use than at the end of use, and therefore error diagnosis or error detection can be given a higher priority than if the counter reading is high at a later stage of use of the output stage. For example, by assigning a high priority to a low counter reading, it is possible to check whether the short circuit still exists multiple times per diagnostic interval. By assigning a low priority to a high counter reading, it is possible to perform fewer or no switching processes for error diagnosis per diagnostic interval to avoid unnecessary loads and damage to the output stage circuit. For example, if the counter reading is below a predetermined limit value, a high or highest priority can be assigned to the switching process for error diagnosis. If the counter reading approaches this limit value, a low priority can be selected.

[0012] Conventionally, the number of short-circuit switching processes performed per diagnostic interval is limited to a fixed maximum, depending, for example, on the type of each power stage, the power supply, the applied system, the configuration, the sensors used, the current ambient temperature, etc. Conventionally, when a short circuit is detected, an error notification is issued, particularly by activating the engine check lamp, and a check is made at fixed intervals during the diagnostic interval by further switch-on processes to determine whether the short circuit still exists, up to the fixed maximum number of short-circuit switching processes per diagnostic interval. If the short circuit has not been corrected by that time, the corresponding function of the control device is often permanently shut down for the remainder of the diagnostic interval. Even if the short circuit is corrected during this diagnostic interval, it can no longer be confirmed, and the corresponding function remains shut down. A check for a short circuit can then be performed again during a subsequent diagnostic interval.

[0013] In contrast, the method uses counter readings to dynamically adapt the frequency of error checking for each diagnostic interval, particularly based on the length of use. Because correction is more likely at an early stage of use than at a later stage of use, more frequent checking is performed to detect correction of a short circuit, avoiding unnecessary blanket shutdown of the control device even though the short circuit no longer exists. After a longer period of use, correction becomes less likely, but the risk of damaging the output stage circuitry increases, so error checking may be performed less frequently or not at all at each diagnostic interval.

[0014] Preferably, the number of short-circuit switching processes that are performed, are to be performed, or may be performed during a diagnostic interval or a running cycle, in particular during a current diagnostic interval or running cycle, is limited depending on the counter reading or the current value of the counter reading. As explained above, in conventional methods, short-circuit switching processes for error diagnosis are often limited collectively to a static fixed value for each diagnostic interval. In contrast, by introducing counter readings, the number of short-circuit switching processes that are allowed per diagnostic interval can be dynamically, particularly preferably, limited over the life of the circuit, and in particular can be dynamically adapted to the number of short-circuit switching processes that the circuit has already performed during its previous life.

[0015] According to a preferred embodiment, the counter reading or the current value of the counter reading is compared with a predetermined threshold value. For example, this threshold value can be set according to a minimum number of short-circuit switching processes that the output stage circuit must endure during its lifetime. This threshold value can indicate, for example, that the number of short-circuit switching processes performed so far is gradually approaching this minimum number, increasing the risk of circuit damage. When the threshold value is reached or exceeded, further switching-on processes can be stopped or prohibited. Preferably, short-circuit switching processes are prioritized and / or the number of short-circuit switching processes is limited depending on the comparison of the current counter reading with the predetermined threshold value. Thus, rather than a static global limitation of switching processes, particularly per diagnostic section, the frequency of switching processes permitted in the event of a short circuit can be dynamically adapted depending on the current lifetime of the output stage circuit.

[0016] In particular, the maximum number of short-circuit switching processes that may be performed during the diagnostic interval can be set as a threshold value as explained above. It is particularly preferred that the threshold value is set depending on the number of diagnostic intervals to be carried out, and therefore the threshold value can preferably be dynamically adapted depending on the age of the output stage circuit to date.

[0017] Advantageously, the threshold value, particularly for the current diagnostic interval, is set according to a (for example, linear or logarithmic) relationship between the number of short-circuit switching processes permitted and one of the diagnostic intervals performed so far. The logarithmic relationship allows a large number of short-circuit switching processes to be permitted per diagnostic interval, particularly at the beginning of the use life of the output stage. As the output stage circuit approaches the minimum number of short-circuit switching processes that it must at least tolerate during its use life, the number of short-circuit switching processes permitted per diagnostic interval can be reduced.

[0018] Preferably, the threshold value, particularly for the current diagnostic interval, is set according to the maximum number of short-circuit switching processes that may be performed during the use of the circuit, in particular according to the difference between the number of short-circuit switching processes and the maximum number of short-circuit switching processes that may be performed during the use of the circuit. This relationship allows a larger number of short-circuit switching processes to be permitted per diagnostic interval, particularly if the difference from the maximum value is large. As the maximum value is approached, the number of short-circuit switching processes permitted per diagnostic interval decreases in order to protect the circuit.

[0019] Preferably, the counter reading is incremented only if the evaluation detects that the high-side switch of the circuit performs a switch-on process during a short circuit to ground and / or that the low-side switch of the circuit performs a switch-on process during a short circuit to the supply voltage. For output stages located on the ground side, or low-side switches with terminals connected to ground, or low-side switches with a load between the switch and the supply voltage, it is particularly preferable to record the switching processes during such short circuits in the counter readings. On the other hand, for output stages located on the supply side, i.e., high-side switches with terminals connected to the supply voltage, or high-side switches with a load between the switch and ground, it is particularly preferable to record the switching processes during a short circuit to ground in the counter readings.

[0020] A computing device according to the invention, for example a control device of a (motor) vehicle, is configured in particular by means of programming techniques to carry out the method according to the invention. Further advantages and embodiments of the invention will become apparent from the description and accompanying drawings.

[0021] The invention is illustrated diagrammatically by way of example in the drawings and will be explained below with reference to the drawings. [Brief explanation of the drawings]

[0022] [Figure 1] 1 shows a schematic representation of a control device comprising an output stage circuit configured to carry out a preferred embodiment of the method according to the invention; [Figure 2] 1 shows a schematic block diagram of a preferred embodiment of the method according to the invention; FIG. [Figure 3] 3 shows a schematic diagram of the number of permissible short-circuit switching processes plotted against the number of driving cycles performed, which can be determined in the course of a preferred embodiment of the method according to the invention; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0023] In FIG. 1, a control system for an (automotive) vehicle is shown diagrammatically and designated 100 . The control device 100 can be provided, for example, as an engine control device for controlling an internal combustion engine 130 and comprises a microcontroller 110 and a semiconductor output stage circuit 120, for example in the form of a MOSFET bridge circuit with high-side and / or low-side switches. By means of corresponding control pulses, the microcontroller 110 can control the driving of these semiconductor switching elements of the output stage circuit 120.

[0024] Output stage 120 is configured to withstand a minimum number of short-circuit switching processes without damage, beyond which there may be an increased risk of damage or destruction to output stage 120 and control device 100.

[0025] To prevent this risk, the control device 100 is configured, in particular by means of programming techniques, to carry out a preferred embodiment of the method according to the invention, which is shown schematically as a block diagram in FIG. 2 and which will be described below.

[0026] In step 201, the control device 100 or the corresponding (automotive) vehicle is operated in the normal manner. In step 202, information about the control device 100, in particular information characterizing the current operation of the control device, is detected. In particular, this information relates to the current signals or drive control pulses of the microcontroller 110 for driving and controlling the output stage circuit 120, and currently existing errors in the control device 100. For example, this information may include the duty cycle of the drive control signals of the semiconductor switching elements, the current through the semiconductor switching elements, and error memory information or entries in the error memory.

[0027] In step 203, this information is evaluated as to whether a short-circuit switching process exists, i.e., whether a drive control pulse or (switch-on) pulse is output from the microcontroller 110 to the output stage circuit 120 while an error condition in the form of a short circuit exists in the output stage circuit 120, and in particular whether the high-side switch of the output stage circuit 120 is thus performing a switch-on process relative to ground and / or whether the low-side switch is performing a switch-on process relative to the supply power source (e.g., a battery).

[0028] If this is not the case and no such short-circuit switching process exists, information about the control device is further detected in step 202 and evaluated in step 203 . On the other hand, if step 203 detects that such a short-circuit switching process exists, then step 204 updates or increments a counter reading that characterizes the number of short-circuit switching processes that have been performed over the lifetime of output stage circuit 120. The current value of this counter reading thus corresponds to the total number of short-circuit switching processes that output stage circuit 120 has performed within control device 100 since the beginning of the lifetime or since first operation.

[0029] This counter reading can be read, for example, in a workshop and used for troubleshooting, repairs, or verifying warranty claims. For example, based on the counter reading it can be checked whether the driver of the vehicle has ignored a warning, such as an activated engine check light, for an extended period of time, which can lead to a reduction or elimination of warranty service by the manufacturer of the control device 100.

[0030] In step 205, the counter reading or the current value of the counter reading is compared with a threshold value, in particular with the maximum number of short-circuit switching processes that may be carried out during a diagnostic interval or driving cycle for fault diagnosis.

[0031] In conventional methods, the number of short-circuit switching processes allowed per diagnostic interval is often statically limited to a fixed value, but by introducing the counter reading, it is possible to flexibly and dynamically adjust the number of short-circuit switching processes allowed per diagnostic interval according to the number of short-circuit switching processes that the circuit 120 has already performed during its lifetime.

[0032] The threshold value is set according to, among other things, the number of diagnostic intervals already performed by the output stage circuit 120 or the vehicle. For example, in the early stages of the life of the output stage circuit 120, a larger number of short-circuit switching processes per diagnostic interval may be allowed than in later stages because the possibility of short-circuit recovery is higher in the early stages of the life of the output stage circuit 120. In particular, the threshold value for the current diagnostic interval is set according to a linear or logarithmic relationship between the number of short-circuit switching processes allowed and the number of diagnostic intervals already performed.

[0033] Based on the threshold comparison 205, step 206 limits the number of short-circuit switching processes that may still be performed in the current diagnostic interval for error diagnosis. Also, step 206 can perform prioritization of individual short-circuit switching processes based on the comparison result. For example, in the early stages of use of circuit 120, short-circuit switching processes can be assigned a high or highest priority during error diagnosis, and a high or unlimited number of such switching processes can be allowed for error diagnosis per diagnostic interval because of the high probability of recovery or error correction. In the later stages of use after many diagnostic intervals have been performed, for example, a low priority can be selected for such short-circuit switching processes for error diagnosis, and only one attempt or one switching process can be set for error diagnosis to avoid possible damage or destruction of control device 100.

[0034] In FIG. 3 the number of allowed short-circuit switching processes m is shown diagrammatically plotted against the number of diagnostic intervals n performed. Curve 310 represents the corresponding linear relationship and curve 320 represents the corresponding logarithmic relationship, according to which the threshold for the current diagnostic interval can be set in step 205 .

[0035] M represents the minimum number of short-circuit switching processes that the output stage circuit 120 must endure during its lifetime. For example, 315 indicates the number of short-circuit switching processes allowed for the diagnostic horizon N1 according to the linear relationship 310, and 325 indicates the number of short-circuit switching processes allowed for the diagnostic horizon N1 according to the logarithmic relationship 320.

[0036] Logarithmic relationship 320 allows more short-circuit switching processes per diagnostic interval than linear relationship 310 allows, especially early in the life of circuit 120. Logarithmic relationship 320 also allows fewer short-circuit switching processes per diagnostic interval as the minimum number M is approached.

[0037] For example, the number of short-circuit switching processes allowed per diagnostic interval can be calculated online during the current diagnostic interval based on a logarithmic relationship 320 via Taylor expansion. A qualitatively similar curve is obtained if the threshold is set according to the difference between the number of short-circuit switching processes and the maximum number of short-circuit switching processes that may be performed during the life of the circuit. Thus, particularly when the difference from the maximum is large, a large number of short-circuit switching processes are allowed per diagnostic interval. As the maximum value is approached, fewer short-circuit switching processes are allowed per diagnostic interval in order to protect the circuit.

Claims

1. A method for monitoring a short-circuit switching process of a circuit (120) of a control device (100), comprising: Information about the control device (100) is detected (202) and evaluated (203) as to whether a short-circuit switching process exists and whether the circuit (120) performs a switch-on process during a short circuit; If during the evaluation (203) a short-circuit switching process is detected, a counter reading is updated (204), the counter reading characterizing the number of short-circuit switching processes performed over the life of the circuit (120). In the method, If during the evaluation (203) it is detected that the high-side switch of the circuit (120) performs a switch-on process during a short circuit to ground and / or that the low-side switch of the circuit (120) performs a switch-on process during a short circuit to battery, the counter reading is updated (204). method.

2. 2. The method of claim 1, wherein the circuit (120) is an output stage circuit (120).

3. The method of claim 1 or 2, wherein the counter reading is compared (205) with a predetermined threshold value.

4. The method of claim 3 , wherein the predetermined threshold is set according to a number of diagnostic intervals.

5. The method of claim 4, wherein the predetermined threshold is set according to a relationship (310) between a number of short-circuit switching processes and a number of diagnostic intervals.

6. 4. The method of claim 3, wherein the predetermined threshold is set according to a maximum number of short-circuit switching processes that may be performed during the life of the circuit (120).

7. 7. The method of claim 6, wherein the predetermined threshold is set according to the difference between the number of short-circuit switching processes and a maximum number of short-circuit switching processes that may be performed during the life of the circuit (120).

8. A computing device (100) configured to perform the method according to claim 1 or 2.

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