WO2013023941A1 - Method and device for detecting a failure of electronic units in printed circuit board assemblies - Google Patents

Method and device for detecting a failure of electronic units in printed circuit board assemblies Download PDF

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Publication number
WO2013023941A1
WO2013023941A1 PCT/EP2012/065271 EP2012065271W WO2013023941A1 WO 2013023941 A1 WO2013023941 A1 WO 2013023941A1 EP 2012065271 W EP2012065271 W EP 2012065271W WO 2013023941 A1 WO2013023941 A1 WO 2013023941A1
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WO
WIPO (PCT)
Prior art keywords
electronic units
printed circuit
power
activating
indication
Prior art date
Application number
PCT/EP2012/065271
Other languages
French (fr)
Inventor
Gernot Riedel
Leonardo MONTOYA
Roland Schmidt
Original Assignee
Abb Research Ltd
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 Abb Research Ltd filed Critical Abb Research Ltd
Publication of WO2013023941A1 publication Critical patent/WO2013023941A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/28—Testing of electronic circuits, e.g. by signal tracer
    • G01R31/2801—Testing of printed circuits, backplanes, motherboards, hybrid circuits or carriers for multichip packages [MCP]
    • G01R31/2803—Testing of printed circuits, backplanes, motherboards, hybrid circuits or carriers for multichip packages [MCP] by means of functional tests, e.g. logic-circuit-simulation or algorithms therefor

Definitions

  • the present invention relates to printed circuit board assemblies of a power converter having a number of electronic units.
  • the present invention further relates to testing and detecting a failure of electronic units in a power converter by means of their power consumption.
  • Electronic systems on printed circuit board assemblies usually have a number of electronic units interconnected with each other to provide the system function.
  • a circuit malfunction in one or more of the electronic units can cause a failure of the electronic system. Due to the increasing number of electronic units used in modern electronic systems, detecting which of the electronic unit(s) has an error is difficult and expensive. Also, monitoring only a portion of the electronic units would only cover a portion of the many failure possibilities.
  • Document US 2009 0222224 A1 discloses a current flow monitoring system with a monitoring device which receives sensing values from a set of current sensors in a system.
  • Document 2006 212266 A1 discloses a method for reducing the debugging time of computer motherboards by examining the turn-on power sequence of the board.
  • the motherboard comprises separate power rails to each of them a coding unit is coupled. Sequentially, each of the power rails is turned on and is outputting a signal to the corresponding coding unit.
  • Each coding signal unit is sending a signal to the status indication unit which indicating e.g. over LEDs, which of the power rails fails. Therefore, each signal from each power rail is used individually to indicate the functionality of the respective power rail.
  • a method for detecting a failure of electronic units on a printed circuit board assembly of a power converter comprising of the following steps:
  • the indication of an electrical parameter change includes at least one of the current consumption of the printed circuit board assembly, the power consumption of the printed circuit board assembly, a phase shift between a supply current and a supply voltage and a ripple current of the printed circuit board assembly;
  • One consideration of the above method is to monitor a timely progression of a change of an electrical parameter related to the printed circuit board assembly in total.
  • a failure is detected when it is determined that the characteristics of the electrical parameter is outside a range indicated by a provided reference parameter change.
  • the electrical parameter which can be for example the current consumption or the power consumption of the printed circuit board assembly, or a phase shift between a supply current and a supply voltage or a supply voltage or a ripple current of the printed circuit board assembly is in timely progression used and is then tested, whether during power-up the next electronic unit the change of the electrical parameter is still in a specified tolerance range.
  • the monitoring is performed during a power-up sequence, in which the electronic units are sequentially activated (powered up), so that they can be addressed individually. Activation of individual electronic units leads to a change of the electrical parameter of the printed circuit board assembly of a power converter, which is cross referenced against a reference parameter change that defines the respective pre- specified range to determine whether or not the respective electronic unit provided a conflicting electrical parameter change indicating a malfunction.
  • a faulty electronic unit on the printed circuit board assembly of a power converter might provide a low impedance path (short circuit) resulting in a local hotspot and at an increased current, thereby exceeding an upper threshold of the respective pre- specified range of a current consumption.
  • a failure in an electronic unit might also lead to a reduced current consumption that falls short of the lower threshold of the respective pre-specified range.
  • problematic electronic units can be identified by abnormal change of the electrical parameter which is monitored in a back-end test, so that an electrical unit may be changed before the system is shipped to the customer.
  • the above-proposed monitoring method is based on a single continuous monitoring of an electrical parameter in a power supply line that supplies power to all parts of the printed circuit board assembly of a power converter.
  • each electronic unit can be addressed individually.
  • the electrical parameter change between the power-up sequence steps is individually attributed to electronic units, which thereby can be monitored by comparing the indication of the electrical parameter change with reference parameter changes.
  • the failure may be signaled if the indication of the electrical parameter change is out of a tolerated range that is associated with the provided reference parameter change of the respective electrical unit.
  • the step of consecutively activating the one or more electronic units according to the power-up sequence may include enabling a power supply unit, which supplies at least one of the one or more electronic units, and/or closing a switch for connecting at least one of the one or more electronic units with a supply source.
  • the step of obtaining an indication of an electrical parameter change may be performed by measuring an indication of the electrical parameter before and after each activation of the one or more electronic units and calculating the difference.
  • the indication of the electrical parameter after each activating of the one or more electronic units may be obtained after a predetermined period of time after the respective activation of the one or more electronic unit(s) or by averaging the indication of the electrical parameter after respective activation of the one or more electronic unit(s) within a predetermined time period.
  • the indication of the electrical parameter may include at least one of the current consumption of the printed circuit board assembly, the power consumption of the printed circuit board assembly, a phase shift between a supply current and a supply voltage and a ripple current of the printed circuit board assembly.
  • a device for detecting failures of electronic units on a printed circuit board assembly of a power converter comprises:
  • the indication of the electrical parameter includes at least one of the current consumption of the printed circuit board assembly, the power consumption of the printed circuit board assembly, a phase shift between a supply current and a supply voltage and a ripple current of the printed circuit board assembly,
  • a reference means for providing a reference parameter change associated to the one or more electrical units
  • the means for consecutively activating may comprise a processing unit which is configured to consecutively activate one or more of the electronic units according to the power-up sequence.
  • the means for consecutively activating may include that the electronic units are adapted to self-activate after a respective predetermined time after power- up so that a consecutive activating of the electronic units is performed.
  • a method for monitoring an operability of electronic units in a system comprising:
  • the device may be comprised of one of the printed circuit boards.
  • Figure 1 schematically shows a topology of an electronic system on a printed circuit board assembly having electronic units that are 'powered up' controlled by a digital processing unit;
  • Figure 2 schematically shows another topology of an electronic system on a printed circuit board assembly according to another embodiment
  • Figure 3 shows a diagram of the current/power consumption of an electronic system with a power-up sequence for electronic units
  • Figure 4 shows a flow chart illustrating a method for monitoring the operability of electronic units
  • Figure 5 shows the power consumptions of individual electronic units and the tolerated bands for the current/power consumption of each of the electronic units.
  • Figure 1 schematically shows a system that is implemented on a printed circuit board assembly 1 of a power converter having one or more printed circuit boards 2.
  • the printed circuit boards 2 of the printed circuit board assembly each include a number of electronic and/or electrical units 3, each of which can be powered up by means of a power supply unit 4.
  • the printed board assembly 1 may further include discrete or distinct elements such as additional electronic and/or electrical units 3, such as electro mechanical components, e.g. encoders, motors, buttons, keyboards, sensors, electro magnetic components, such as relais, transformers, inductors and the like.
  • the printed circuit boards 2 of the printed circuit board assembly can have a variety of electronic units 3.
  • the electronic units 2 can include analog and digital circuits, transceivers for automotive applications, drivers for external devices like relays and sensors, and user interface devices like displays, touch screens and the like.
  • a first printed circuit board 2 includes a communication interface and an analog circuitry and a second printed circuit board 2 includes a digital circuitry and external load drivers as electronic circuits 3.
  • the power supply units 4 for powering the electronic units 3 are all connected to a common supply line 5. Electrical power is supplied via the common supply line 5 to the power supply units 4 so that the electronic unit 3 that it is associated with is supplied in a suitable manner.
  • a measurement device 6 is provided for measuring a current through the supply line 5.
  • the measurement device 6 may be implemented by means of a shunt and a sensing circuit 8.
  • the sensing circuit 7 is to detect an indication of the current flowing through the supply line 5, such as a voltage over the shunt or the like. Alternatively, the sensing circuit 6 is adapted to measure any other indication for the power consumed by the system 1 .
  • a digital processing unit 8 is provided, which includes a monitoring unit, is located on the first printed circuit board 2 and is supplied with electric power at the start-up of the system 1 via an associated power supply unit 4.
  • the digital processing unit 8 then carries out a power-up sequence, wherein the electronic units 3 are subsequently supplied with electrical power via the respective power supply unit 4.
  • the power supply unit 4 may be provided with an enable input EN for switching the power supply unit 4 on or off or a separate switch 9 can be provided to switch the power supply unit 4 if it has no enable input.
  • the digital processing unit 8 then controls the enable inputs of the power supply unit 4 and the switches 9 to power up each of the electronic units 3 in a according to a timely scheme.
  • FIG. 2 schematically shows a further embodiment of a system 1 which shows two or more electronic units 3 that can be selectively supplied with power by one power supply unit 4.
  • the switches 9 can also be provided downstream of a power supply unit 4 that serves in supplying power to electronic units 3 operated with the same voltage/power level.
  • the switches 9 then split off one or more electronic units 3 from the same power supply unit 4.
  • a further power supply unit 10 can be coupled in series with the power supply unit 4 to provide a voltage level for driving internal or external electronic units.
  • two electronic units 3 are supplied with power at the same time, e.g. at power-up, such as the digital processing unit 8 and a further electronic unit 3 having a digital circuitry.
  • the power supply unit 4 supplying the digital processing unit 8 and the further electronic unit 3 cannot be enabled or switched.
  • the current that is first measured after powering up can be used for diagnosing the correct operation of both electronic units 3 (i. e. the digital processing unit 8 and the digital circuitry).
  • the measurement device 6, the sensing unit 7, the digital processing unit 8, the switch 9, the monitoring unit 1 1 , the comparator 12 and the reference memory 13 could each be a part of one or more of the printed circuit boards 2 or can be provided as separate units external from printed circuit boards 2.
  • the current/power consumption detected by the measurement device 6 gradually increases, as shown in Figure 3.
  • the digital processing unit 8 controls the power supply units 4 and the switches 9 to power up the electronic units 3 in a predetermined sequence.
  • the total current/power consumption measured in the supply line 5 continuously increases substantially stepwise or according to the increasing power consumption as the individual electronic units 4 are activated.
  • the switches 9 can be partly or fully self-controlled such that each switch 9 switches on the associated electronic unit 3 after a predetermined time after initially applying power to the printed circuit board assembly 1 of a power converter. The result is a self-initiated power-up sequence that does not require any processing unit 8 to control the switches 9.
  • the digital processing unit 8 comprises of a monitoring unit 1 1 that comprises a comparator 12 and a reference memory 13.
  • a monitoring unit 1 1 that comprises a comparator 12 and a reference memory 13.
  • the printed circuit board assembly of a power converter or at least some of its electronic units 3, needs to be set to a well defined operating point, e.g. by applying one or more signals with special switching frequencies, by applying a predetermined processor loading or, in case of a transmission device, by applying transmission signals with a predetermined baud rate. Therefore, a test mode could be initiated during the power-up sequence.
  • a flow chart illustrates the method of monitoring the operability of electronic units 3 in a printed circuit board assembly (system 1 ) of a power converter.
  • step SI After supplying the supply voltage to the printed circuit board assembly via the supply lines 5 in step SI , the digital processing unit 8 and its power supply unit 4, which adapts the voltage and power level to the needs of the digital processing unit 8, is immediately supplied with electric power.
  • a booting procedure is started and is adapted to carry out a powering-up sequence for the additional electronic units 3 of the system 1 (step S2).
  • step S3 a monitoring procedure is started and reads out the sensing unit 7 and compares the indication of the current/power consumption with a reference current/power consumption change by means of the comparator 12.
  • a characteristic of the reference current/power consumption is previously stored in the reference memory 13 and is defined by the timely progression of the current/power consumption due to the predetermined power-up sequence.
  • any kind of reference means that provides an indication of a characteristic of the reference current/power consumption can be provided.
  • the indication about the characteristic of the reference current/power consumption can also be obtained externally.
  • the characteristics describe the current/power consumption of each electronic unit 3 for the case that they work correctly. The characteristics may further describe tolerated ranges of the current/power consumptions of the electronic units 3.
  • step S4 according to the predetermined power-up sequence a first electronic unit 3 (or an electronic unit 3 that has not been activated yet) is powered by enabling the associated power supply unit 4 (or closing a respective switch 9) controlled by the digital processing unit 8.
  • step S5 an indication of the actual current/power consumption of the activated electronic unit(s) 3 is obtained from the measuring unit 7 the difference as a current/power consumption change is calculated between the actual current/power consumption after activating the recently activated electronic unit 3 and the current/power consumption, which exists before activating the recently activated electronic unit 3. Furthermore, the reference current/power consumption change of the respective electronic unit 3 (or several electronic units 3) is read out from the reference memory 13 included in the digital processing unit 8.
  • the indication of the actual current/power consumption of the activated electronic unit(s) 3 is obtained after a predetermined period of time after the activation of the electronic unit(s) 3 or by averaging the actual current/power consumption within a predetermined time period after the activation of the electronic unit(s) 3.
  • step S6 it is determined whether the actual current/power consumption change caused by the electronic unit 3, activated in step S4, is within the associated tolerated range of the current/power consumption change allowed or not allowed for the respective electronic unit 3. If positive (alternative: yes), it is continued with step S7. Otherwise (alternative: no), if it is determined in step S6 that the actual measured current/power consumption is outside the tolerated range as provided by step S5, it is signaled in step S8 that a failure has occurred, e.g. an error signal is provided, which might activate an indicator to provide a notification of the error.
  • the notification can also include information about the respective failed electronic unit 3 and information about which current/power consumption fell out of the tolerated range.
  • step S7 It is checked in step S7 whether or not the recently checked electronic unit 3 was the last electronic unit 3, of which the correct operability was to be monitored. If not (alternative: no), the method is continued with step S4, wherein the next electronic unit 3 is activated and wherein in step S5 the respective range for the current/power consumption is read out from the respective memory of the monitoring unit 7.
  • step S7 If it is determined in step S7 that no further electronic unit 3 is to be monitored, the method is discontinued and it is signaled in step S8 that no failure has occurred.
  • Ranges of acceptable current/power consumption changes can be defined by a statistical analysis of experimental data.
  • the tolerated ranges can be defined as the statistical average of plus/minus four times the standard deviation (4 ⁇ ).
  • the tolerated ranges are illustrated for a number of electronic units 4.
  • the tolerated ranges for the power levels of the first three electronic units 3 are narrow while the tolerated range for the power level of a fourth electronic unit 3 is wide, such that if one only monitored the total power consumption the diagnostic method would not be efficient since failures of the first three electronic units 3 would not be detected.
  • the narrow ranges associated with the first three electronic units 2 can be utilized for the corresponding electronic units 3, thus making it an efficient monitoring tool.
  • the acceptance ranges can be set separately for each individual printed circuit board assembly.
  • a fingerprint could be stored locally in the reference memory 13 of digital processing unit 8 of the printed circuit board assembly after its manufacture, thereby, variations in production could be ignored and failures compared to an initial state can be defined.
  • phase shift between voltage and current and/or induced ripple current may also be used as failure indicator.
  • an indicator describing the phase shift or induced ripple current, respectively must be defined, which determines a phase shift change or induced ripple current change when a next electronic unit 2 is powered up.
  • the current measurement is carried out to provide an indication of the supply current or an indication of the supplied power (product of supply voltage and current).
  • a power indication it must be ensured that the supply voltage is low in variations. If voltage variations are to be expected, a compensation for the voltage variations should be provided by means of a voltage measurement, such that the power consumption can be continuously calculated using the actual supply voltage and the actual supply current.

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  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
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Abstract

The present invention relates to a method for detecting failures of electronic units (3) in a printed circuit board assembly (1), comprising the following steps of: consecutively activating the electronic units (3) according to a power-up sequence,wherein in each activating step one or more of the electronic units (3) are activated; after each step of activating one or more of the electronic units (3), obtaining an indication of an electrical parameter change with respect to a state before activating the one or more electronic units (3) and comparing the indication of the electrical parameter change with a provided reference parameter change associated to the one or more electrical units (3); and signaling a failure depending on the result of each comparing step.

Description

Method and device for detecting a failure of electronic units in printed circuit board assemblies
DESCRIPTION
Technical Field
The present invention relates to printed circuit board assemblies of a power converter having a number of electronic units. The present invention further relates to testing and detecting a failure of electronic units in a power converter by means of their power consumption.
Related art
Electronic systems on printed circuit board assemblies usually have a number of electronic units interconnected with each other to provide the system function. A circuit malfunction in one or more of the electronic units can cause a failure of the electronic system. Due to the increasing number of electronic units used in modern electronic systems, detecting which of the electronic unit(s) has an error is difficult and expensive. Also, monitoring only a portion of the electronic units would only cover a portion of the many failure possibilities.
From document DE 10 2007 007 339 A1 an error detection method to detect errors in electronic printed circuit boards is known. To detect an error test, parameters of a test circuit are measured via monitoring pins and compared with reference parameters to determine whether or not an error exists on a printed circuit board.
Document US 2009 0222224 A1 discloses a current flow monitoring system with a monitoring device which receives sensing values from a set of current sensors in a system. Document 2006 212266 A1 discloses a method for reducing the debugging time of computer motherboards by examining the turn-on power sequence of the board. The motherboard comprises separate power rails to each of them a coding unit is coupled. Sequentially, each of the power rails is turned on and is outputting a signal to the corresponding coding unit. Each coding signal unit is sending a signal to the status indication unit which indicating e.g. over LEDs, which of the power rails fails. Therefore, each signal from each power rail is used individually to indicate the functionality of the respective power rail.
It is therefore an object of the present invention to provide a method and a device that monitors the operability of electronic units on a printed circuit board assembly independent of its individual function. It is a further object of the present invention to provide inexpensive global monitoring, in particular with a reduced number of detecting devices.
Summary of the invention
The above objects are achieved by the method of detecting a failure of electronic units on a printed circuit board assembly of a power converter according to claim 1 and by the device and the system according to the further independent claims.
Further embodiments of the present invention are indicated in the dependent subclaims.
According to a first aspect a method for detecting a failure of electronic units on a printed circuit board assembly of a power converter, comprising of the following steps:
- consecutively activating the electronic units according to a power-up
sequence, wherein in each activating step one or more of the electronic units (3) are activated;
- after each step of activating one or more electronic units, obtaining an
indication of an electrical parameter change, with respect to a state before activating the one or more electronic units, and comparing the indication of the electrical parameter change with a provided reference parameter change associated with the one or more electrical units, wherein the indication of the electrical parameter includes at least one of the current consumption of the printed circuit board assembly, the power consumption of the printed circuit board assembly, a phase shift between a supply current and a supply voltage and a ripple current of the printed circuit board assembly;
- signaling a failure depending on the result of each comparing step.
One consideration of the above method is to monitor a timely progression of a change of an electrical parameter related to the printed circuit board assembly in total. A failure is detected when it is determined that the characteristics of the electrical parameter is outside a range indicated by a provided reference parameter change. In other words, the electrical parameter which can be for example the current consumption or the power consumption of the printed circuit board assembly, or a phase shift between a supply current and a supply voltage or a supply voltage or a ripple current of the printed circuit board assembly is in timely progression used and is then tested, whether during power-up the next electronic unit the change of the electrical parameter is still in a specified tolerance range.
The monitoring is performed during a power-up sequence, in which the electronic units are sequentially activated (powered up), so that they can be addressed individually. Activation of individual electronic units leads to a change of the electrical parameter of the printed circuit board assembly of a power converter, which is cross referenced against a reference parameter change that defines the respective pre- specified range to determine whether or not the respective electronic unit provided a conflicting electrical parameter change indicating a malfunction.
A faulty electronic unit on the printed circuit board assembly of a power converter might provide a low impedance path (short circuit) resulting in a local hotspot and at an increased current, thereby exceeding an upper threshold of the respective pre- specified range of a current consumption. A failure in an electronic unit might also lead to a reduced current consumption that falls short of the lower threshold of the respective pre-specified range. By using the power-up sequence in which the electronic units are subsequently powered up, so that the electrical parameter gradually changes, the electrical parameter change related to each individual electronic unit powered up one at a time can be monitored.
As a result, problematic electronic units can be identified by abnormal change of the electrical parameter which is monitored in a back-end test, so that an electrical unit may be changed before the system is shipped to the customer.
The above-proposed monitoring method is based on a single continuous monitoring of an electrical parameter in a power supply line that supplies power to all parts of the printed circuit board assembly of a power converter. In combination with power-up sequencing, each electronic unit can be addressed individually. The electrical parameter change between the power-up sequence steps is individually attributed to electronic units, which thereby can be monitored by comparing the indication of the electrical parameter change with reference parameter changes.
Moreover, the failure may be signaled if the indication of the electrical parameter change is out of a tolerated range that is associated with the provided reference parameter change of the respective electrical unit.
The step of consecutively activating the one or more electronic units according to the power-up sequence may include enabling a power supply unit, which supplies at least one of the one or more electronic units, and/or closing a switch for connecting at least one of the one or more electronic units with a supply source.
In another embodiment, the step of obtaining an indication of an electrical parameter change may be performed by measuring an indication of the electrical parameter before and after each activation of the one or more electronic units and calculating the difference.
Particularly, the indication of the electrical parameter after each activating of the one or more electronic units may be obtained after a predetermined period of time after the respective activation of the one or more electronic unit(s) or by averaging the indication of the electrical parameter after respective activation of the one or more electronic unit(s) within a predetermined time period. Furthermore, the indication of the electrical parameter may include at least one of the current consumption of the printed circuit board assembly, the power consumption of the printed circuit board assembly, a phase shift between a supply current and a supply voltage and a ripple current of the printed circuit board assembly.
According to a further aspect, a device for detecting failures of electronic units on a printed circuit board assembly of a power converter comprises:
- a means for consecutively activating the electronic units (3) according to a power-up sequence, wherein in each activating step one or more of the electronic units (3) are activated,
- a means for obtaining an indication of an electrical parameter change with respect to a state before activating the one or more electronic units after each activation of the one or more electronic units, wherein the indication of the electrical parameter includes at least one of the current consumption of the printed circuit board assembly, the power consumption of the printed circuit board assembly, a phase shift between a supply current and a supply voltage and a ripple current of the printed circuit board assembly,
- a reference means for providing a reference parameter change associated to the one or more electrical units;
- a comparator for comparing the indication of the electrical parameter
change with the provided reference parameter change;
- a signaling means for signaling a failure depending on the result of each comparison.
Moreover, the means for consecutively activating may comprise a processing unit which is configured to consecutively activate one or more of the electronic units according to the power-up sequence.
Alternatively, the means for consecutively activating may include that the electronic units are adapted to self-activate after a respective predetermined time after power- up so that a consecutive activating of the electronic units is performed. According to a further aspect, a method for monitoring an operability of electronic units in a system, comprising:
- the above device;
- one of more printed circuit boards each having one of more of the electronic units. Furthermore, the device may be comprised of one of the printed circuit boards.
Brief description of the drawings
Preferred embodiments of the present invention will be described in more detail in conjunction with the accompanying drawings in which:
Figure 1 schematically shows a topology of an electronic system on a printed circuit board assembly having electronic units that are 'powered up' controlled by a digital processing unit;
Figure 2 schematically shows another topology of an electronic system on a printed circuit board assembly according to another embodiment;
Figure 3 shows a diagram of the current/power consumption of an electronic system with a power-up sequence for electronic units;
Figure 4 shows a flow chart illustrating a method for monitoring the operability of electronic units; and
Figure 5 shows the power consumptions of individual electronic units and the tolerated bands for the current/power consumption of each of the electronic units.
Description of embodiments
Figure 1 schematically shows a system that is implemented on a printed circuit board assembly 1 of a power converter having one or more printed circuit boards 2. The printed circuit boards 2 of the printed circuit board assembly each include a number of electronic and/or electrical units 3, each of which can be powered up by means of a power supply unit 4. The printed board assembly 1 may further include discrete or distinct elements such as additional electronic and/or electrical units 3, such as electro mechanical components, e.g. encoders, motors, buttons, keyboards, sensors, electro magnetic components, such as relais, transformers, inductors and the like. The printed circuit boards 2 of the printed circuit board assembly can have a variety of electronic units 3. The electronic units 2 can include analog and digital circuits, transceivers for automotive applications, drivers for external devices like relays and sensors, and user interface devices like displays, touch screens and the like. In the present example, a first printed circuit board 2 includes a communication interface and an analog circuitry and a second printed circuit board 2 includes a digital circuitry and external load drivers as electronic circuits 3.
The power supply units 4 for powering the electronic units 3 are all connected to a common supply line 5. Electrical power is supplied via the common supply line 5 to the power supply units 4 so that the electronic unit 3 that it is associated with is supplied in a suitable manner. In the supply line 5, a measurement device 6 is provided for measuring a current through the supply line 5. The measurement device 6 may be implemented by means of a shunt and a sensing circuit 8. The sensing circuit 7 is to detect an indication of the current flowing through the supply line 5, such as a voltage over the shunt or the like. Alternatively, the sensing circuit 6 is adapted to measure any other indication for the power consumed by the system 1 .
A digital processing unit 8 is provided, which includes a monitoring unit, is located on the first printed circuit board 2 and is supplied with electric power at the start-up of the system 1 via an associated power supply unit 4. The digital processing unit 8 then carries out a power-up sequence, wherein the electronic units 3 are subsequently supplied with electrical power via the respective power supply unit 4. To supply the electronic unit 3 with power from the supply line 5, the power supply unit 4 may be provided with an enable input EN for switching the power supply unit 4 on or off or a separate switch 9 can be provided to switch the power supply unit 4 if it has no enable input. The digital processing unit 8 then controls the enable inputs of the power supply unit 4 and the switches 9 to power up each of the electronic units 3 in a according to a timely scheme.
Figure 2 schematically shows a further embodiment of a system 1 which shows two or more electronic units 3 that can be selectively supplied with power by one power supply unit 4. This ensures that the switches 9 can also be provided downstream of a power supply unit 4 that serves in supplying power to electronic units 3 operated with the same voltage/power level. The switches 9 then split off one or more electronic units 3 from the same power supply unit 4. Also a further power supply unit 10 can be coupled in series with the power supply unit 4 to provide a voltage level for driving internal or external electronic units.
Furthermore, it can be provided that two electronic units 3 are supplied with power at the same time, e.g. at power-up, such as the digital processing unit 8 and a further electronic unit 3 having a digital circuitry. This may be the case when the power supply unit 4 supplying the digital processing unit 8 and the further electronic unit 3 cannot be enabled or switched. In this case, the current that is first measured after powering up can be used for diagnosing the correct operation of both electronic units 3 (i. e. the digital processing unit 8 and the digital circuitry).
The measurement device 6, the sensing unit 7, the digital processing unit 8, the switch 9, the monitoring unit 1 1 , the comparator 12 and the reference memory 13 could each be a part of one or more of the printed circuit boards 2 or can be provided as separate units external from printed circuit boards 2.
When powering up the digital processing unit 8, the current/power consumption detected by the measurement device 6 gradually increases, as shown in Figure 3. After powering up the digital processing unit 8, it controls the power supply units 4 and the switches 9 to power up the electronic units 3 in a predetermined sequence. As a result, the total current/power consumption measured in the supply line 5 continuously increases substantially stepwise or according to the increasing power consumption as the individual electronic units 4 are activated. In an alternative embodiment, the switches 9 can be partly or fully self-controlled such that each switch 9 switches on the associated electronic unit 3 after a predetermined time after initially applying power to the printed circuit board assembly 1 of a power converter. The result is a self-initiated power-up sequence that does not require any processing unit 8 to control the switches 9.
The digital processing unit 8 comprises of a monitoring unit 1 1 that comprises a comparator 12 and a reference memory 13. When carrying out the power-up sequence for powering all electronic units 4, the indication of the current or the power supplied to the system 1 in total is permanently monitored and compared with an expected progression of a current/power consumption reference, continuously during power-up sequence, or at predetermined times after each activation step when the next electronic unit 3 is activated or the like.
In some cases it might be preferred that the printed circuit board assembly of a power converter, or at least some of its electronic units 3, needs to be set to a well defined operating point, e.g. by applying one or more signals with special switching frequencies, by applying a predetermined processor loading or, in case of a transmission device, by applying transmission signals with a predetermined baud rate. Therefore, a test mode could be initiated during the power-up sequence.
In Figure 4, a flow chart illustrates the method of monitoring the operability of electronic units 3 in a printed circuit board assembly (system 1 ) of a power converter.
After supplying the supply voltage to the printed circuit board assembly via the supply lines 5 in step SI , the digital processing unit 8 and its power supply unit 4, which adapts the voltage and power level to the needs of the digital processing unit 8, is immediately supplied with electric power. A booting procedure is started and is adapted to carry out a powering-up sequence for the additional electronic units 3 of the system 1 (step S2). Furthermore, in step S3 a monitoring procedure is started and reads out the sensing unit 7 and compares the indication of the current/power consumption with a reference current/power consumption change by means of the comparator 12. A characteristic of the reference current/power consumption is previously stored in the reference memory 13 and is defined by the timely progression of the current/power consumption due to the predetermined power-up sequence. Instead of using the reference memory 13, any kind of reference means that provides an indication of a characteristic of the reference current/power consumption can be provided. The indication about the characteristic of the reference current/power consumption can also be obtained externally. The characteristics describe the current/power consumption of each electronic unit 3 for the case that they work correctly. The characteristics may further describe tolerated ranges of the current/power consumptions of the electronic units 3.
In step S4, according to the predetermined power-up sequence a first electronic unit 3 (or an electronic unit 3 that has not been activated yet) is powered by enabling the associated power supply unit 4 (or closing a respective switch 9) controlled by the digital processing unit 8.
In step S5 an indication of the actual current/power consumption of the activated electronic unit(s) 3 is obtained from the measuring unit 7 the difference as a current/power consumption change is calculated between the actual current/power consumption after activating the recently activated electronic unit 3 and the current/power consumption, which exists before activating the recently activated electronic unit 3. Furthermore, the reference current/power consumption change of the respective electronic unit 3 (or several electronic units 3) is read out from the reference memory 13 included in the digital processing unit 8.
Preferably, the indication of the actual current/power consumption of the activated electronic unit(s) 3 is obtained after a predetermined period of time after the activation of the electronic unit(s) 3 or by averaging the actual current/power consumption within a predetermined time period after the activation of the electronic unit(s) 3.
In step S6 it is determined whether the actual current/power consumption change caused by the electronic unit 3, activated in step S4, is within the associated tolerated range of the current/power consumption change allowed or not allowed for the respective electronic unit 3. If positive (alternative: yes), it is continued with step S7. Otherwise (alternative: no), if it is determined in step S6 that the actual measured current/power consumption is outside the tolerated range as provided by step S5, it is signaled in step S8 that a failure has occurred, e.g. an error signal is provided, which might activate an indicator to provide a notification of the error. The notification can also include information about the respective failed electronic unit 3 and information about which current/power consumption fell out of the tolerated range.
It is checked in step S7 whether or not the recently checked electronic unit 3 was the last electronic unit 3, of which the correct operability was to be monitored. If not (alternative: no), the method is continued with step S4, wherein the next electronic unit 3 is activated and wherein in step S5 the respective range for the current/power consumption is read out from the respective memory of the monitoring unit 7.
If it is determined in step S7 that no further electronic unit 3 is to be monitored, the method is discontinued and it is signaled in step S8 that no failure has occurred.
Ranges of acceptable current/power consumption changes can be defined by a statistical analysis of experimental data. For example, the tolerated ranges can be defined as the statistical average of plus/minus four times the standard deviation (4σ). In Figure 5 the tolerated ranges are illustrated for a number of electronic units 4. The tolerated ranges for the power levels of the first three electronic units 3 are narrow while the tolerated range for the power level of a fourth electronic unit 3 is wide, such that if one only monitored the total power consumption the diagnostic method would not be efficient since failures of the first three electronic units 3 would not be detected. With the present invention, the narrow ranges associated with the first three electronic units 2 can be utilized for the corresponding electronic units 3, thus making it an efficient monitoring tool.
Instead of using a statistical approach for defining the tolerated ranges for a given type of printed circuit board assembly of a power converter, the acceptance ranges can be set separately for each individual printed circuit board assembly. Such a fingerprint could be stored locally in the reference memory 13 of digital processing unit 8 of the printed circuit board assembly after its manufacture, thereby, variations in production could be ignored and failures compared to an initial state can be defined.
After activating a respective one of the electronic units 3, the current/power consumption change caused by the activation of the electronic unit 3 is detected, such that it is possible to only assess the current/power consumption of the respective electronic unit 3. Hence, any current/power consumption offset from the previous electronic units 3 already powered up does not affect the monitoring of the operability of the respective electronic unit 3.
Apart from the measurement of the current through the supply line 5, other global electrical parameters, such as phase shift between voltage and current and/or induced ripple current, may also be used as failure indicator. In both cases, an indicator describing the phase shift or induced ripple current, respectively, must be defined, which determines a phase shift change or induced ripple current change when a next electronic unit 2 is powered up.
As described above, the current measurement is carried out to provide an indication of the supply current or an indication of the supplied power (product of supply voltage and current). In case of a power indication, it must be ensured that the supply voltage is low in variations. If voltage variations are to be expected, a compensation for the voltage variations should be provided by means of a voltage measurement, such that the power consumption can be continuously calculated using the actual supply voltage and the actual supply current.
REFERENCE LIST printed circuit board assembly of a power converter printed circuit board
electronic unit
power supply unit
supply line
measurement device
sensing unit
digital processing unit
switch
further power supply unit
monitoring unit
comparator
reference memory

Claims

1 . Method for detecting failures of electronic units (3) in a printed circuit board assembly (1 ) of a power converter, comprising the following steps of:
- consecutively activating the electronic units (3) according to a power-up sequence, wherein in each activating step one or more of the electronic units (3) are activated;
- after each step of activating one or more of the electronic units (3),
obtaining an indication of an electrical parameter change with respect to a state before activating the one or more electronic units (3) and comparing the indication of the electrical parameter change with a provided reference parameter change associated to the one or more electrical units (3), wherein the indication of the electrical parameter includes at least one of the current consumption of the printed circuit board assembly (1 ), the power consumption of the printed circuit board assembly (1 ), a phase shift between a supply current and a supply voltage and a ripple current of the printed circuit board assembly (1 ); and
- signaling a failure depending on the result of each comparing step.
2. Method according to claim 1 , wherein the failure is signaled if the indication of the electrical parameter change is out of a tolerated range associated with the provided reference parameter change of the respective electrical unit.
3. Method according to claim 1 or 2, wherein the step of consecutively activating the one or more electronic units (3) according to the power-up sequence, includes enabling a power supply unit (4) supplying at least one of the one or more electronic units (3) and/or closing a switch (9) for connecting at least one of the one or more electronic units (3) with a supply source.
4. Method according to one of the claims 1 to 3, wherein obtaining an indication of an electrical parameter change is performed by measuring an indication of the electrical parameter before and after each activating of the one or more electronic units (3) and calculating the difference.
5. Method according to claim 4, wherein the indication of the electrical parameter after each activating of the one or more electronic units (3) is obtained after a predetermined period of time after the respective activation of the one or more electronic unit(s) 3 or by averaging the indication of the electrical parameter after respective activation of the one or more electronic units (3) within a predetermined time period.
6. Device for detecting failures of electronic units (3) in a printed circuit board assembly (1 ) of a power converter, comprising:
- a means for consecutively activating the electronic units (3) according to a power-up sequence, wherein in each activating step one or more of the electronic units (3) are activated,
- a means for obtaining an indication of an electrical parameter change with respect to a state before activating the one or more electronic units (3) after each activation of the one or more electronic units (3), wherein the indication of the electrical parameter includes at least one of the current consumption of the printed circuit board assembly (1 ), the power consumption of the printed circuit board assembly (1 ), a phase shift between a supply current and a supply voltage and a ripple current of the printed circuit board assembly (1 ),
- a reference means (13) for providing a reference parameter change
associated to the one or more electrical units (3);
- a comparator (12) for comparing the indication of the electrical parameter change with the provided reference parameter change; and
- a signaling means for signaling a failure depending on the result of each comparison.
7. Device according to claim 6, wherein the means for consecutively activating further comprises a processing unit for consecutively activating one or more of the electronic units (3) according to a power-up sequence.
8. Device according to claim 6, wherein the means for consecutively activating includes that the electronic units (3) are adapted to self-activate after a respective predetermined time after power-up so that a consecutive activating of the electronic units (3) is performed.
9. System comprising:
- a device according to one of the claims 6 or 8;
- one of more printed circuit boards (2) each having one of more of the electronic units (3).
10. System according to claim 9, wherein the device is comprised on one of the printed circuit boards (2).
PCT/EP2012/065271 2011-08-17 2012-08-03 Method and device for detecting a failure of electronic units in printed circuit board assemblies WO2013023941A1 (en)

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Application Number Priority Date Filing Date Title
EP11177809 2011-08-17
EP11177809.8 2011-08-17

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