DE19611522B4 - Method and device for fault detection in an output stage circuit arrangement - Google Patents

Abstract

method for fault detection in an output stage circuit arrangement, wherein at least one trained as a switchable solenoid valve, with the Power amplifier arrangement to be operated consumer means a first switching means with a supply voltage and means a second switching means is connectable to ground, wherein a Connection point between the first switching means and the consumer is applied with a predetermined potential and at the connection point voltage applied is evaluated for error detection, wherein the first switching means and / or the second switching means so short is / are brought into a defined state that the consumer does not change its switching state, and the voltage at the connection point between the first switching means and the consumer compared with given values and starting from the comparison is detected on error and that a control the switching means, which is a change of Switching state of the consumer has, only takes place when no error was detected.

Description

State of the art

The The invention relates to a method and a device for error detection in an output stage circuit arrangement.

From the DE 43 38 462 A1 a control system for electrical consumers in motor vehicles is known, with a microcomputer which is electrically conductively connected to a control input of at least one electrical switching device for reversing this, wherein the connected to the vehicle ground load on the switching path of the switching device is connected to the supply voltage, with a Measuring device for measuring the voltage applied to the load, which is connected via a measuring line to the consumer, wherein the microcomputer evaluates the measured voltage as a function of the type and operating state of the consumer and generates error signals when measured by the measuring device voltages of predetermined Deviate from the limits. In this case, in order to best rule out possible disturbances due to the strongly fluctuating supply voltage during the fault determination, the microcomputer is electrically conductively connected to a constant current source which is connected to the load to supply the consumer with a test current via the measuring line to the consumer, the microcomputer generates test signals which simultaneously Switching device for short-term shutdown of the supply voltage and for charging the load with a test current to be supplied and the test current generated by the constant current source depending on the type and the operating state of the consumer of the microcomputer reversible.

The DE 40 12 109 C2 describes a device for monitoring the operation of an electrical or electronic switching means, its connected load, its control and its connection line. This comprises at least one parallel to the switching means connected fault detection logic, wherein the connection point between the switching means and the load is applied to a reference potential, wherein the potentials of the input and output terminal of the switching means and the reference potential can be applied to the error detection logic, and wherein the error detection logic starting from The applied potentials between the faults short circuit to positive pole, load drop and short circuit to ground differentiates.

The DE 2715 116 C3 shows a device for monitoring the electric lighting of motor vehicles with a test circuit connected in parallel with the lighting circuits, which contains voltage-dependent switching elements and actuates a display device in response to a voltage difference caused by failure of a lamp. The test circuits connected in parallel with the lighting switches present in the motor vehicle have switchable series resistors in the form of transistors which send a test current in the order of magnitude of the lamp operating current through the lamp or lamp groups during the test procedure. Furthermore, they have facilities that evaluate an excess of a predetermined, depending on the type of lamp circuit voltage value set during the test process and bring to display.

A method and an apparatus for error detection in an output stage circuit arrangement are known from DE-OS 40 12 19 known. There, an error detection logic is connected in parallel to the output stage. In this device, a consumer is connected with its one terminal to the supply voltage and is connected via a switching means to ground. An error detection logic evaluates the potentials at the input of the switching means and at the connection point between switching means and consumers. The connection point between the switch and the consumer is supplied with a reference voltage in order to be able to reliably differentiate between different types of fault.

From the US 4,589,401 a circuit arrangement for driving a consumer is known, in which the consumer is connected via a first switching means with supply voltage and via a second switching means to ground.

The Providing a reference voltage requires a considerable amount of energy circuit complexity. Furthermore, there is a surveillance the first switching means, the consumer with supply voltage connects, not provided.

A review of Device is only possible in the prior art if the first switch, which connects the consumer to supply voltage, works properly and is in its closed state. For this reason must the first switch to be short circuit proof, which increased Cost conditionally. In the procedure according to the invention can be cheaper safety switch can be used since before commissioning its functioning is checked.

Shunts and parasitic Resistors in the Wiring harness can not recognized in the prior art.

Object of the invention

Of the The invention is based on the object, also in output stage circuit arrangements, in which first and second switching means are present to monitor them. This object is achieved by the features characterized in the independent claims solved.

Advantages of the invention

With the procedure of the invention a simple and inexpensive Error detection in an output stage circuit arrangement possible with the consumer with a switching means to ground and with a second switching means is switched against supply voltage.

drawing

The invention will be explained below with reference to the embodiment shown in the drawing. Show it 1 a schematic circuit of the device according to the invention and 2 a flow chart of the procedure according to the invention.

Description of the embodiments

in the The following is the procedure according to the invention described using the example of an output stage circuit arrangement for an ABS control unit. In an ABS system, the flow of brake fluid controlled with different solenoid valves. A failure of one of Components, in particular the switching means, the solenoid valves drive, sure be recognized. In case of an error, appropriate measures initiate. The procedure according to the invention is not limited to ABS systems, it can also be used by others Systems where hydraulic fluid is controlled by solenoid valves, for example in systems with ASR (traction control) or with FDR (vehicle dynamics control) be used.

Of further it is possible also with other solenoid valves, in particular for controlling the amount of fuel to be used in motor vehicles, proceed accordingly.

The procedure according to the invention is explained below using the example of two consumers. A first consumer is with 100 and a second consumer with 105 designated. The procedure according to the invention is not limited to use with two consumers. It can also be done when driving one or more consumers accordingly.

The two consumers 105 and 100 both are connected to a first terminal of a first switching means 110 in connection. The second terminal of the first switching means 110 is connected to the supply voltage Ubat. The first consumer 100 is via a second switching means 120 in contact with ground GND. Accordingly, the second consumer 105 via a second switching means 125 in contact with earth.

The first switching means 110 is commonly referred to as a high-side switch or as a safety switch. The second switching means 125 and 120 are commonly referred to as a low-side switch or as an actuator switch. As switching means preferably transistors, in particular field effect transistors are used.

The switching means 110 . 120 and 125 be from a control unit 130 subjected to control signals. The supply voltage Ubat is via a further switching means 140 with the control unit 130 in connection. At the output of the switching means 140 the voltage is usually referred to as ignition voltage UZ. At the switch 140 it is an ignition switch operated by the driver. When the motor vehicle is off, this switch is usually open and closed when the ignition is switched on.

The ground terminal GND is further connected via a first resistance means 150 with the connection point between the consumers 100 and 105 and the first switching means 110 in connection. This connection point also has a second resistance means 155 with supply voltage Ubat or with the ignition voltage UZ in conjunction. The connection point between the first switching means 110 to the consumers 100 and 105 as well as the two resistance means 150 and 155 also stands with the control unit 130 in connection.

This device works as follows: If the driver operates the ignition switch 140 so becomes the control unit 130 subjected to the ignition voltage. Based on signals not shown, the control unit calculates 130 Control signals for acting on the switching means 110 . 125 and 120 , Depending on the control of the switching means 110 . 120 and 125 becomes the current flow through the consumers 100 and 105 Approved.

According to the invention it is provided that the safety switch 110 releases the current flow only when it is detected that there is no error. The control unit controls for error monitoring 130 the switching means 110 . 120 and 125 one after the other at short notice and evaluate those at the connection point 115 voltage applied. Detects the control unit 130 . that there is no error, so the switch 110 controlled so that it releases the flow of current. By controlling the low-side switch 120 and 125 the corresponding consumers are activated.

For evaluation, the connection point 115 charged with a predetermined potential. Starting from the comparison of the potential at the connection point 115 with predeterminable values, the control unit recognizes 130 on error or error-free state. The predeterminable potential for the connection point 115 According to the invention with the high-impedance voltage divider consisting of the resistors 150 and 155 provided. The values of the resistors 150 and 155 are chosen so that they are much larger than the ohmic resistance of the consumer 100 , The current flow through the voltage divider consisting of the resistors 150 and 155 is therefore negligible.

The potential at the connection point becomes dependent on the switching state of the switching means 110 . 120 and 125 predefined values compared. At the connection point 115 depends on the values of the resistors 150 and 155 a fraction of the supply voltage Ubat or the ignition voltage UZ.

The control of the switching means 110 . 120 and 125 in the error check can be made so short that the potential 115 can be evaluated, but there is still no change in the switching state of the consumer.

An embodiment of the procedure for verification according to the invention is described below with reference to the flowchart of 2 explained in more detail.

In the following embodiment, the resistors 150 and 155 chosen so that they have the same resistance values. In this case, it is at the connection point 115 with opened switching means a voltage which corresponds to half of the ignition voltage UZ or half of the supply voltage Ubat. In the following embodiment, the voltage divider is applied to the ignition voltage. The values of the resistors are chosen so that they are significantly higher than the resistance values of the consumers.

In further embodiments, the voltage divider can also be supplied with the supply voltage Ubat. Furthermore, other ratios for the values of the resistors can be chosen. In such other embodiments, the thresholds with which the voltage at the connection point 115 be selected accordingly.

The check for accuracy is preferably carried out before each activation of the safety switch 110 , That is, the check is carried out at least after each startup of the control unit 130 that is after each closing of the ignition switch 140 ,

In a first step 200 becomes the high-side switch 110 controlled such that it interrupts the flow of current. In the subsequent step 205 become the low-side switches 120 and 125 controlled so that they interrupt the flow of electricity. If there is no fault in this condition, the voltage divider, consisting of the resistors, will be activated 150 and 155 that at the connection point 115 a voltage is applied that corresponds to UZ / 2. The subsequent query 210 checks whether at the connection point, the voltage U is equal to the value UZ / 2.

If the voltage is not equal to UZ / 2, the query follows 215 , which checks if the voltage reaches the value UZ. If this is the case, the step recognizes 220 in that there is a short circuit to supply voltage Ubat. If this is not the case, the query is checked 225 whether the voltage U at the connection point 115 corresponds to the ground potential GND. If this is the case, the step recognizes 230 on short to ground.

If this is not the case, then the following queries check whether there is a shunt. To do this, the query checks 235 whether the voltage U at the connection point 115 reduced by the voltage UZ / 2 is greater than a threshold US. If this is the case, the block recognizes 240 on shunt after supply voltage Ubat. If this is not the case, the query is checked 245 whether the voltage U at the connection point 115 reduced by UZ / 2 is less than a threshold US. If this is the case, then in step 250 detected on shunt to ground. If this is not the case, then step 255 ,

Recognizes the query 210 in that the voltage U is at the connection point 115 is equal to the voltage UZ / 2, so also follows step 255 , In the steps 210 to 250 It is checked whether there is a short circuit or a shunt to ground or supply voltage.

In step 255 the first low-side switch LS is driven so that it closes. If there is no error here, the connection point must be 115 at ground potential GND. The subsequent query 260 therefore checks if the connection point 150 is at ground potential. If this is not the case, the query is checked 265 whether the voltage U at the connection point 115 takes the value UZ / 2. If this is the case, then in step 270 recognized that the low-side switch LS is defective. If this is not the case, the voltage assumes a different value, then another error F must be present. This will be in step 272 recognized. The steps 255 and 260 are processed consecutively for all low-side switches.

Recognizes the query 260 that the connection point 115 If the GND is at ground potential when the low-side switch is closed, then step follows 275 , In the steps 255 to 272 the low-side switches are checked.

In step 275 the low-side switches LS are driven so that they lock and the high-side switch is driven so that it releases the connection. In this case, the connection point must 115 lie on supply voltage.

The query 285 Check if the voltage U at the connection point 115 takes the value UZ / 2. If this is the case, then in step 290 detected on defect of the high-side switch. If this is not the case, the query is checked 292 whether the voltage U is equal to the ignition voltage UZ. If this is not the case, then in step 294 detected on error F. If this is the case, then in step 296 recognized that also the high-side switch HS is working properly. So there is no mistake.

In the steps 275 to 294 the high-side switch is checked. The check for short circuit or shunt, the checking of the low-side switch and the check of the high-side switch can also be done in a different order. For example, first the steps 255 to 272 and then the steps 210 to 250 be processed. The review of the high-side switch is last.

If there is no error, follow in step 298 the control of the switching means 110 . 120 and 125 in the same way as the control unit 130 wishes to the consumers 100 and 105 to bring in the appropriate position.

With The procedure according to the invention can also shunts and parasitic resistors be recognized.

The switching means are checked without the actuator being driven in such a way that it reacts. Error of the safety switch 110 can be detected before its activation.

Claims (4)

Method for error detection in an output stage circuit arrangement, wherein at least one designed as a switchable solenoid valve, Consumer to be operated with the power amplifier circuit arrangement by means of a first switching means with a supply voltage and connectable to ground by means of a second switching means, wherein a connection point between the first switching means and the Consumer is charged with a predetermined potential and the voltage applied to the connection point for fault detection is evaluated, wherein the first switching means and / or the second Switching means is brought so short in a defined state /, that the consumer does not change his switching state, and the voltage at Connection point between the first switching means and the consumer compared with given values and based on the comparison is detected on error and that a control of the switching means, the one change the switching state of the consumer results, only takes place, if no error was detected. Method according to claim 1, characterized in that that this predeterminable potential by means of a high-impedance voltage divider provided. Device according to claim 1, characterized in that that the first switching means a first resistance means and the consumer a second resistance means is connected in parallel and the two Resistance means form the high-impedance voltage divider. Device according to one of the preceding claims, characterized characterized in that Consumers are used in particular in ABS, ASR, FDR systems.