GB2300530A - Method and circuit arrangement for monitoring a power output stage - Google Patents

Method and circuit arrangement for monitoring a power output stage Download PDF

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Publication number
GB2300530A
GB2300530A GB9609342A GB9609342A GB2300530A GB 2300530 A GB2300530 A GB 2300530A GB 9609342 A GB9609342 A GB 9609342A GB 9609342 A GB9609342 A GB 9609342A GB 2300530 A GB2300530 A GB 2300530A
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GB
United Kingdom
Prior art keywords
output stage
power output
control
monitoring
signal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB9609342A
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GB9609342D0 (en
Inventor
Joern Heining
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Original Assignee
Siemens AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens AG filed Critical Siemens AG
Publication of GB9609342D0 publication Critical patent/GB9609342D0/en
Publication of GB2300530A publication Critical patent/GB2300530A/en
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/18—Modifications for indicating state of switch
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
    • F02P17/00—Testing of ignition installations, e.g. in combination with adjusting; Testing of ignition timing in compression-ignition engines
    • F02P17/12—Testing characteristics of the spark, ignition voltage or current
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
    • F02P3/00—Other installations
    • F02P3/02—Other installations having inductive energy storage, e.g. arrangements of induction coils
    • F02P3/04—Layout of circuits
    • F02P3/055—Layout of circuits with protective means to prevent damage to the circuit, e.g. semiconductor devices or the ignition coil
    • F02P3/0552—Opening or closing the primary coil circuit with semiconductor devices
    • F02P3/0554—Opening or closing the primary coil circuit with semiconductor devices using digital techniques
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/08—Modifications for protecting switching circuit against overcurrent or overvoltage
    • H03K17/082—Modifications for protecting switching circuit against overcurrent or overvoltage by feedback from the output to the control circuit
    • H03K17/0826—Modifications for protecting switching circuit against overcurrent or overvoltage by feedback from the output to the control circuit in bipolar transistor switches

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Ignition Installations For Internal Combustion Engines (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)

Abstract

The monitoring system uses a diagnosis circuit (T3) with a comparator. It compares the rectangular control signal (st) for the power output stage (T2), provided by the ignition control microprocessor, with the output signal (d) of the power output stage twice during each control signal. The comparison points lie at defined time points from the beginning and end of the control signal, with the delivery of the output signal blocked when an fault is detected.

Description

is 2300530 METHOD-AND A CIRCUIT ARRANGEMENT FOR MONITORING A POWER OUTPUT
STAGE The invention relates to a method for monitoring a power output stage, which is switched into a conductive state by a control signal, by comparing the control signal with the output signal of the power output stage, as well as to a circuit arrangement for monitoring a power output stage. The method and circuit arrangement are particularly suitable for use in a motor vehicle ignition control circuit.
A transistor output stage without a microprocessor, which transistor output stage is shortcircuit-proof against the operating voltage of the load and in which the switching transistor is controlled in a nonconductive manner if the voltage at the load falls below a predeterminable value, is known from WO 91/15058.
A protective circuit for a switching transistor whose control voltage and collector voltage, obtained via optocouplers, are compared with each other is known from US 4,375,073. This circuit cannot recognise a line interruption and is too costly for use in a motor vehicle.
A further circuit, with which a line interruption and a short circuit can be recognised but which, however, requires two window comparators, two logic circuits and one flip-flop in order to do this, is known from DE 41 00 790. This circuit is not, however, suitable for motor vehicle ignition control units, because when the collector voltage of the switching transistor is dying out (at the end of the burning life of the spark plugs, following the closed duration), it produces at least one L-signal, which can be evaluated as a short-circuit.
The present invention seeks to provide a method for monitoring and protecting a power output stage, in particular for a motor vehicle ignition control unit, during interruption of the line from the switching transistor to the load, as well as during a shortcircuit of the load to earth or to the working voltage (at which the load lies), and to provide a circuit arrangement for monitoring a power output stage which determines with certainty the occurrence of the abovementioned events and which, as a result of the low cost of components, is suitable for use in a motor vehicle.
According to a first aspect of the invention, there is provided a method for monitoring a power output stage which is controlled by means of a control signal to be alternately in a conducting and a nonconducting state, comprising the steps of:
comparing each control signal with a respective resulting output signal of the power output stage; determining whether successive comparisons indicate an error at the output of the power output stage; and causing the power output stage to be in a nonconducting state if an error is detected.
According to a second aspect of the invention, there is provided a circuit arrangement for monitoring a power output stage having a load- switching transistor, for supplying power to a load, and a microprocessor for controlling the switch on of the load-switching transistor, the circuit arrangement consisting of a control voltage source and a diagnostic transistor, having a first terminal connected to the control voltage source; a second terminal connected to the control voltage source by way of a diode and to the collector of the switching transistor by way of a resistor; and a third terminal connected to a diagnostic input of the microprocessor.
For a better understanding of the present invention, and to show how it may be brought into effect, reference will now be made, by way of example, to the accompanying drawings, in which:
Figure 1 shows a circuit of an ignition power output stage; Figure 2 shows a circuit, in accordance with the invention, of an ignition power output stage; and Figure 3 shows signal graphs for various operating states of the circuit in accordance with the invention; Figure 3a shows the control signal st emitted by the microprocessor; Figure 3b shows the collector potential of the switching transistor T2 during normal operation; Figure 3c shows the diagnostic signal d during normal operation; Figure 3d shows the diagnostic signal d during a short circuit to battery voltage; Figure 3e shows the diagnostic signal d in the event of a cable break or short circuit to earth; Figure 3f shows a comparison between the logic states of the control signal st (Figure 3a) and the diagnostic signal d (Figure 3c) at the interrogation instants ti and t3 during normal operation; Figure 39 shows a comparison between the logic states of the control signal st (Figure 3a) and the diagnostic signal d (Figure 3d) at the interrogation instants tl and t3 during a short circuit to battery voltage U+; and Figure 3h shows a comparison between the logic states of the control signal st (Figure 3a) and the diagnostic signal d (Figure 3e) at the interrogation instants tl and t3 in the event of a cable break or short circuit to earth GND.
The circuit, shown in Figure 1, of a simple, previously known to the applicant, power output stage of a motor vehicle ignition control unit has a pnpcontrol transistor T1 and a Darlington pair switching transistor T2 in a standard protective circuit for activating an ignition coil ZS by means of the control signals st produced by a microprocessor gP. The output stage is normally neither protected against short circuits nor capable of diagnosis, so that a line interruption between the collector of T2 and the load, here the ignition coil, cannot be recognised.
Circuits of this type, which ensure with the aid of a shunt and a supplementary circuit that the collector current of the switching transistor is limited, are also known, but the power loss which occurs in the shunt is disadvantageous.
Figure 2 shows a circuit, in accordance with the invention, of an ignition power output stage as part of a motor control unit (not shown in greater detail), which circuit has a simple structure and can also recognise line interruptions between the collector of the output stage switching transistor T2 and the ignition coil ZS, as well as short circuits to operating voltage U+ and to earth GND, and in this event can suppress control signals in order to save the output stage from destruction.
The circuit of the power output stage consists of a control transistor Ti, which, by means of the resistors R2, R3 and R4 and also the diode DI, is wired as a current source, and a switching transistor T2, which is controlled by said control transistor TI. The collector-emitter-section of the switching transistor T2 is in series with the primary winding W of an ignition coil between the positive pole U+ and the negative pole GND of an operating voltage source (12V) (not represented).
The power output stage is controlled by the control signals st of a microprocessor gP of the motor control unit. The part of the control signal st that conductively controls the transistors is termed a control pulse (st = L). The microprocessor gP and the power output stage are supplied by a control voltage source (SV) (not represented), which has a positive pole vc and a negative pole GND, which is common with the negative pole of the working voltage source.
Inserted between the collector of the switching transistor T2 (which is constructed as a Darlington pair transistor) and the positive pole Vcc of the control voltage source is a diagnostic circuit. The latter consists of a diagnostic transistor T3, the emitter E of which is connected to the positive pole Vc,: and the base B of which is likewise connected to the positive pole V,,,by way of a diode D2 and is connected to the collector C of the switching transistor T2 by way of a resistor RS. A diagnostic signal d can be obtained at the collector C of the diagnostic transistor T3, and is supplied to a diagnostic input EDi.g of the microprocessor gP.
The resistors R6 and R7 at the collectors of the transistors T2 and T3 are so-called "pull down" resistors, which draw the potential of the associated transistor in its blocking state to earth (GND). The capacitor K is used to smooth voltage peaks.
The operating principle of the circuit shown in Figure 2 is based on: a control of the switching transistor T2 with a defined base current (from the current source T1); a monitoring of the saturation voltage (collector voltage) of said switching transistor by way of the diagnostic signal d; and a comparison of this diagnostic signal with the control signal in the microprocessor gP. By appropriate selection of the base current of the switching transistor T2, it is possible to ensure that the switching transistor T2 is saturated during normal operation, i.e. at current strengths <l0A. At collector currents which clearly exceed this value, the is transistor T2 is in the linear range. As a result of this, the collector voltage increases because the transistor T2 also functions as a current source. The diagnostic transistor T3 compares the collector voltage of the switching transistor T2 with a threshold value (Vcc - 0.7V) which corresponds to the control voltage Ve, which is reduced by the amount of the blocking voltage of the diode D2.
Signal graphs for various operating states of the circuit in accordance with the invention are shown in Figure 3.
If, in the event of regular function of the circuit, the control voltage st is at H-level (+SV), then all three transistors T1, T2 and T3 are nonconductive and the diagnostic signal is an L-signal (GND =_ OV). If on the other hand the control signal st is at L-level (OV, control pulse from t2 to t4 in Figure 3a, something which corresponds to the closed time of the primary electric circuit of the ignition coil), then all three transistors are conductive and the diagnostic signal is an H-signal (+SV), Figures 3a and 3c.
At the time instant t4, the control pulse disappears and the transistors become non-conductive. In the spark plugs, an ignition spark begins, the burning life of which can be read off at the increased collector voltage of the switching transistor T2 in the time from t4 to tS, Figure 3b.
As soon as a short-circuit of the primary winding ZS of the ignition coil to battery voltage U+ is present, the collector voltage of the switching transistor T2 is lastingly at a value U+ =_ 12V, and the diagnostic signal d is therefore lastingly an L-signal, Figure 3d.
If, however, there is a short-circuit to earth GND or a line interruption between the collector of the switching transistor T2 and the ignition coil, the collector voltage of the switching transistor T2 is lastingly at a value GND =_ OV and the diagnostic signal d is therefore lastingly an H-signal, Figure 3e.
In accordance with the invention, a discrete-time comparison of the control signal st with the diagnostic signal d is carried out in the microprocessor gP, in each case shortly before the start and shortly before the end of the control pulse, i.e. the closed duration, therefore at the time instants tl = t2 - AT and t3 = t4 - AT. As a result of the fact that the remaining energy stored in the ignition coil dies away in the form of a decaying oscillation after the end of the burning life, a measurement of the signal level at other times is not so certain.
The graphs 3f, 3g and 3h show the logic levels measured (sampled) at these time instants in each case, and in each case show above the time axis the level of the control signal st and beneath the time axis the level of the diagnostic signal d.
Graph 3f shows this level (from Figures 3a and 3c) in the event of normal functioning of the power output stage; Graph 3g shows this level during a short-circuit to battery voltage (from Figures 3a and 3d); and Graph 3h shows this level during a line break or a short-circuit to earth (from Figures 3a and 3e).
From this it can be seen that in the case of this exemplary embodiment, the level of the control signal st and the level of the diagnostic signal d are always inverse with respect to each other during normal operation of the power output stage (Figure 3f), are both equal (L-level) in the event of a short-circuit to battery voltage (Figure 3g) in each case at the time instant t3, and are likewise both equal (H-level) in the event of a line break or a short-circuit to earth (Figure 3h) in each case in the time instant tl.
These states are recognised by the microprocessor gP and it can thereupon certainly protect the switching transistor T2 by switching off the output stage (control signal st is lastingly H-signal).

Claims (11)

1. Method for monitoring a power output stage which is controlled by means of a control signal to be alternately in a conducting and a nonconducting state, comprising the steps of:
comparing each control signal with a respective resulting output signal of the power output stage; determining whether successive comparisons indicate an error at the output of the power output stage; and causing the power output stage to be in a nonconducting state if an error is detected.
2. A method for monitoring a power output stage as claimed in claim 1, wherein the power output stage is caused to be in a conducting and a nonconducting state in response to the two levels of a rectangular waveform control signal.
3. A method for monitoring a power output stage as claimed in claim 2, wherein the signal comparison is carried out a predetermined time prior to the level change in the control signal.
4 A method for monitoring a power output stage substantially as herein described with reference to Figures 2 and 3.
5. Method for monitoring a power output stage, in particular for a motor vehicle ignition control unit, which power output stage is switched into the conductive state by a respective rectangular control pulse of a control signal, which control pulse is produced in a microprocessor of the control unit by means of comparing the control signal with the output signal of the power output stage, characterised in that the signal comparison occurs in the microprocessor twice per control pulse, in each case a predetermined time span before the start and before the end of the control pulse, and in that in the case of a recognised is error, the output of a control signal is stopped.
6. A motor vehicle ignition control unit employing the method as claimed in claims 1-5.
7. A circuit arrangement for monitoring a power output stage having a load-switching transistor, for supplying power to a load, and a microprocessor for controlling the switch on of the load-switching transistor, the circuit arrangement consisting of a control voltage source and a diagnostic transistor, having a first terminal connected to the control voltage source; a second terminal connected to the control voltage source by way of a diode and to the collector of the switching transistor by way of a resistor; and a third terminal connected to a diagnostic input of the microprocessor.
8. A circuit arrangement for monitoring a power output stage as claimed in claim 6, wherein the microprocessor carries out the method of one of claims 1-5.
9. A circuit arrangement for monitoring a power output stage substantially as herein described with reference to Figures 2 and 3.
10. A circuit arrangement for monitoring a power output stage, having between the positive pole and the negative pole of a working voltage source a series Circuit arrangement, which can be controlled by a microprocessor of a control unit and consists of load and a switching transistor, wherein there is provided a control transistor which is wired as a current source and for its part controls the switching transistor, and there is provided a diagnostic circuit which has a diagnostic transistor, the first terminal of which is connected to the positive pole of a control voltage source - the negative pole of this control voltage source being identical to that of the working voltage source and the second terminal of which is connected to the positive pole of the control voltage source by way of a diode and to the collector of the switching transistor by way of a resistor, and the third terminal of said diagnostic transistor is connected to a diagnostic input of the microprocessor.
11. A motor vehicle ignition control unit including a circuit arrangement as claimed in one of claims 7-10.
GB9609342A 1995-05-03 1996-05-03 Method and circuit arrangement for monitoring a power output stage Withdrawn GB2300530A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19516208A DE19516208C1 (en) 1995-05-03 1995-05-03 Automobile ignition control power output stage monitoring system

Publications (2)

Publication Number Publication Date
GB9609342D0 GB9609342D0 (en) 1996-07-10
GB2300530A true GB2300530A (en) 1996-11-06

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GB9609342A Withdrawn GB2300530A (en) 1995-05-03 1996-05-03 Method and circuit arrangement for monitoring a power output stage

Country Status (4)

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KR (1) KR960043515A (en)
DE (1) DE19516208C1 (en)
FR (1) FR2733865A1 (en)
GB (1) GB2300530A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008132509A2 (en) * 2007-04-27 2008-11-06 Cambridge Semiconductor Limited Bipolar transistor drivers
US9035635B2 (en) 2013-03-06 2015-05-19 Microchip Technology Incorporated Using synchronous converter in asynchronous mode to prevent current reversal during battery charging
US11675327B2 (en) 2018-05-25 2023-06-13 Siemens Aktiengesellschaft Fault detection in power supply to a load in terms of a broken wire detection for a functional safety DC output

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3299409B2 (en) * 1995-03-31 2002-07-08 三菱電機株式会社 Ignition device for internal combustion engine

Citations (3)

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Publication number Priority date Publication date Assignee Title
GB2042841A (en) * 1979-01-30 1980-09-24 Sp El Srl Power circuit including a power transistor and means for automatically protecting the power transistor
GB2192317A (en) * 1985-10-11 1988-01-06 Caterpillar Ind Inc Apparatus and method for protecting a motor control circuit
US5365397A (en) * 1992-04-28 1994-11-15 Kabushiki Kaisha Toshiba Device for protecting power semiconductor device against short circuit

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US4375073A (en) * 1980-06-16 1983-02-22 Reliance Electric Company Dual-monitoring protection circuit for switching transistor
DE3322240A1 (en) * 1982-07-23 1984-01-26 Robert Bosch Gmbh, 7000 Stuttgart SAFETY EMERGENCY DEVICE FOR THE IDLE OPERATION OF MOTOR VEHICLES
JPH074644Y2 (en) * 1989-11-10 1995-02-01 アルプス電気株式会社 Load control circuit self-diagnosis circuit
DE4009304A1 (en) * 1990-03-23 1991-09-26 Bosch Gmbh Robert SHORT-CIRCUIT-PROOF TRANSISTOR, IN PARTICULAR IGNITION, FOR MOTOR VEHICLES
DE4100790A1 (en) * 1991-01-12 1992-07-16 Vdo Schindling Monitoring power transistor made conductive by rectangular signal - setting memory element into state indicating defect according to voltage level during time window
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Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2042841A (en) * 1979-01-30 1980-09-24 Sp El Srl Power circuit including a power transistor and means for automatically protecting the power transistor
GB2192317A (en) * 1985-10-11 1988-01-06 Caterpillar Ind Inc Apparatus and method for protecting a motor control circuit
US5365397A (en) * 1992-04-28 1994-11-15 Kabushiki Kaisha Toshiba Device for protecting power semiconductor device against short circuit

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008132509A2 (en) * 2007-04-27 2008-11-06 Cambridge Semiconductor Limited Bipolar transistor drivers
WO2008132509A3 (en) * 2007-04-27 2008-12-24 Cambridge Semiconductor Ltd Bipolar transistor drivers
US7961484B2 (en) 2007-04-27 2011-06-14 Cambridge Semiconductor Limited Bipolar transistor drivers
US9035635B2 (en) 2013-03-06 2015-05-19 Microchip Technology Incorporated Using synchronous converter in asynchronous mode to prevent current reversal during battery charging
CN104956580A (en) * 2013-03-06 2015-09-30 密克罗奇普技术公司 Using synchronous converter in asynchronous mode to prevent current reversal during battery charging
CN104956580B (en) * 2013-03-06 2018-04-17 密克罗奇普技术公司 In Asynchronous Mode using synchronous converter with prevent battery charge during electric current it is reverse
TWI632758B (en) * 2013-03-06 2018-08-11 美商微晶片科技公司 A switch-mode power supply and method for operating the same
US11675327B2 (en) 2018-05-25 2023-06-13 Siemens Aktiengesellschaft Fault detection in power supply to a load in terms of a broken wire detection for a functional safety DC output

Also Published As

Publication number Publication date
FR2733865A1 (en) 1996-11-08
GB9609342D0 (en) 1996-07-10
KR960043515A (en) 1996-12-23
DE19516208C1 (en) 1996-07-25

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