Method and system for identifying a faulty current sensor

Abstract

A method for identifying a faulty current sensor in an electrical installation, wherein the power supply of the electrical installation is at least partially provided by a switched mode power supply circuit, which is connected to at least one current sensor, which samples the current in a phase conductor of the electrical installation, which power supply circuit delivers a regulated voltage, wherein the method comprises the following steps: - determining (S100) the switching duty cycle of the power switch of the switched mode power supply; - analyzing (S102) the determined switching duty cycle; - identifying (S104) a fault condition, if the behavior of the switching duty cycle is representative of a fault of the at least one current sensor.

Description

Technical Field

[0001] This invention relates to a method and system for identifying fault current sensors in electrical equipment.

[0002] The present invention relates more specifically to the field of electrical protection devices and / or electrical measuring devices, such as those used in power distribution facilities, particularly those used in facilities for distributing AC current. Background Technology

[0003] Such electrical devices are typically associated with one or more phase conductors of an electrical installation so as to interrupt the flow of current in these phase conductors, for example, in the event of an electrical fault.

[0004] In known ways, some of these devices can be powered, at least partially, by the current flowing in the phase conductors. These devices are referred to as automatically powered. The current required for the operation of the electrical equipment can be sampled, for example, by a current sensor (e.g., a current transformer installed around each phase conductor). Therefore, the device does not need to be powered by a dedicated power line or an onboard battery. There is also no need to establish a direct electrical connection between the phase conductors and the electrical equipment.

[0005] This greatly simplifies the manufacturing of the equipment and its assembly in electrical installations.

[0006] The disadvantage of these self-powered devices is that, in the event of a failure of one of the current sensors, the device may not be properly powered, which could jeopardize its proper operation and potentially cause unacceptable safety issues. Summary of the Invention

[0007] More specifically, the present invention aims to overcome these disadvantages by providing means and methods for identifying fault current sensors in electrical equipment (especially electrical protection equipment).

[0008] Therefore, one aspect of the present invention relates to a method for identifying faulty current sensors in electrical equipment, wherein the power supply for the electrical equipment is provided at least in part by a switch-mode power supply circuit connected to at least one current sensor, the at least one current sensor sampling the current in the phase conductors of the electrical installation, the power supply circuit delivering a regulated voltage, wherein the method includes the following steps:

[0009] Determine the switching duty cycle of the power switch in the switch-mode power supply;

[0010] Analyze the determined switch duty cycle;

[0011] If the behavior of the switch duty cycle indicates a fault in at least one current sensor, then the fault condition is identified.

[0012] With the aid of this invention, the diagnostic device allows the detection of anomalies in the operation of a current sensor that could jeopardize the proper operation of the device.

[0013] Depending on the advantageous but not essential aspects, this method and system may combine one or more of the following features individually or according to any technically permissible combination:

[0014] The analysis of the switch duty cycle includes comparing the determined switch duty cycle with a predetermined reference value.

[0015] - Select a predetermined reference value based on the amplitude of the current flowing in the phase conductor.

[0016] - The analysis of the switch duty cycle includes a historical analysis of how the duty cycle changes over time relative to past values.

[0017] - Analysis of time-varying behavior using an infinite impulse response filter.

[0018] The analysis of the switch duty cycle includes comparing the determined switch duty cycle with a theoretical value of a comparison duty cycle, which is calculated using current values ​​measured by one or more additional current sensors.

[0019] - The determined duty cycle is the average of the switching duty cycles averaged over a predefined time period (e.g., over a time period corresponding to multiple cycles of current flowing in the phase conductor).

[0020] - An alarm will be automatically issued if a fault condition is detected.

[0021] - Electrical equipment is electrical protection equipment, such as circuit breakers, which automatically triggers if a fault condition is detected.

[0022] The method for identifying faulty sensors also includes the following steps:

[0023] - Measure the total current flowing in one or more phase conductors of an electrical installation using one or more additional current sensors;

[0024] - Measure the total current from the at least one current sensor, and then compare the measured total current value with the current value measured by one or more additional sensors;

[0025] A fault condition is identified if the difference between the total current value from the at least one current sensor and the current value measured by one or more additional sensors is greater than a predefined threshold.

[0026] According to another aspect, an electrical device includes:

[0027] - At least one current sensor is designed to sample the current in the phase conductors of an electrical installation, and

[0028] A switch-mode power supply circuit, connected to the current sensor, is configured to deliver a regulated voltage for supplying power to an electrical device. The electrical device includes a diagnostic device configured to perform the following steps:

[0029] - Determine the switching duty cycle of the power switch in the switch-mode power supply;

[0030] -Analysis of the determined switch duty cycle; and

[0031] - If the behavior of the switch duty cycle indicates a fault in at least one current sensor, then identify the fault condition. Attached Figure Description

[0032] The invention will be better understood from the following description of one embodiment of an electrical protection or measuring device, given only as an example and with reference to the accompanying drawings, in which:

[0033] Figure 1 It is a simplified schematic circuit diagram of electrical equipment associated with electrical facilities, the electrical equipment including a diagnostic device according to an embodiment of the present invention;

[0034] Figure 2 schematically shown Figure 1 An embodiment of a diagnostic device;

[0035] Figure 3 yes Figure 1 A flowchart of the operation method of the diagnostic device;

[0036] Figure 4 This shows the state under normal conditions. Figure 1 A graph showing the changes in electrical quantities during the operation of the diagnostic device.

[0037] Figure 5 It is shown in Figure 1 A graph showing the changes in electrical quantities during another operational phase of the diagnostic device.

[0038] Figure 6 schematically shown Figure 1 Another embodiment of the diagnostic device. Detailed Implementation

[0039] Figure 1 A diagnostic device 2 is shown on an electrical device (not shown), which may be an electrical protection device or an electrical measuring device. For example, the electrical device may be a circuit breaker.

[0040] The electrical equipment is configured to be associated with electrical facilities 4, such as power distribution facilities.

[0041] Electrical installations include one or more phase conductors designed to carry AC current.

[0042] In the example shown, electrical installation 4 includes three-phase conductors (denoted as Ip1, Ip2, and Ip3) for carrying three-phase current and a neutral conductor (denoted as IpN), which will correspond to the phase conductors in the following text.

[0043] This example is non-limiting, and as a variation, the number of phase conductors can be different. The phase conductor associated with neutral IpN can be omitted.

[0044] The electrical device includes a first set of current sensors 6, each current sensor being coupled to phase conductors Ip1, Ip2, Ip3 and IpN.

[0045] For example, the current sensor 6 is a measuring coil (e.g., a Rogowski coil), or a current transformer, or any other similar type of sensor.

[0046] According to an exemplary embodiment, each current sensor 6 includes a core surrounding a phase conductor and a coil wound around the core. The core may be magnetic or non-magnetic (as in the case of a Rogowski coil), and the opposite ends of the coil form the output terminals of the current sensor 6.

[0047] Each current sensor 6 is configured to deliver current when the phase conductor around which the current sensor 6 is mounted carries current.

[0048] Here, the current sensor 6 is connected to the electronic processing circuit 8, which is configured to analyze the current measured by the current sensor 6.

[0049] For example, the electronic processing circuit 8 allows the device to perform functions for monitoring and measuring the current flowing in the electrical installation 4.

[0050] For example, the electronic processing circuit 8 can be connected to the tripping device of the electrical equipment.

[0051] The electrical equipment also includes a second set of current sensors 10, each of which is coupled to one of the phase conductors Ip1, Ip2, Ip3 and IpN.

[0052] For example, current sensor 10 is a sensor based on a magnetic core (e.g., a current transformer), and current sensor 6 is a Rogowski coil.

[0053] The electrical device also includes a switch-mode power supply circuit 12 configured to deliver a power supply voltage, referred to below as the “output voltage,” for supplying power to the electrical device at least partially using current from the current sensor 10.

[0054] In other words, the current sensor 10 allows the device 2 to be powered by the line current flowing in the phase conductor.

[0055] More specifically, the power supply circuit 12 is configured to power at least the measurement and / or monitoring and / or protection functions provided by the electrical equipment, such as powering the tripping device of the electrical equipment.

[0056] For example, power supply circuit 12 may include a power converter and / or a filter circuit and / or a rectifier.

[0057] It is worth noting that the power supply circuit 12 includes a switch-mode power converter configured to convert the AC voltage obtained at the output of the current sensor 10 into a regulated voltage, preferably a DC voltage.

[0058] Advantageously, the power supply circuit 12 includes at least one power switch, such as a power transistor.

[0059] For example, the switching of this power switch allows the output voltage to be rectified, as will be understood below.

[0060] In many implementations, the power supply circuit 12 includes a plurality of such power switches.

[0061] For simplicity, only one such power switch will be described below. However, it should be understood that the embodiments described below can be extended to cases where the power supply circuit 12 includes multiple such power switches.

[0062] The power supply circuit 12 may also include an energy storage device, such as a capacitor, as described below.

[0063] Generally, the diagnostic device 2 is configured to identify faults in one of the current sensors 10 and / or in the power supply circuit 12. For this purpose, the diagnostic device 2 can be based on measurements from the group of current sensors 6 and 10.

[0064] Therefore, according to Figure 1 In the embodiment shown in the schematic circuit diagram, the diagnostic device 2 includes a second electronic processing circuit 14 (also referred to as a control circuit), which includes:

[0065] - The first processing module 18 is configured to generate control signals for controlling the at least one power switch of the power supply circuit 12, and

[0066] - The second processing module 16 is configured to calculate the duty cycle of the operation of the power supply circuit 12, in particular the switching duty cycle of the at least one transistor of the power supply circuit 12.

[0067] In fact, the duty cycle calculated by the second processing module 16 can depend on the switching frequency of the power switch. In other words, the calculated duty cycle can vary over time.

[0068] For example, the second processing module 16 can directly determine the duty cycle based on the control signal from the first processing module 18, for example by measuring the signal or by accessing data used internally by the first processing module 18 to generate the control signal.

[0069] According to another example, see the reference below. Figure 6 As can be seen, the second processing module 16 can measure the current flowing through the power switch. This measurement can be performed using a measuring resistor (shunt resistor) connected in series with the power switch.

[0070] In many embodiments, the first processing module 18 is programmed to control the power switch in order to keep the output voltage of the power supply circuit 12 regulated at a reference voltage value, or, as a variation, within a reference voltage range.

[0071] In other words, the output voltage is regulated by the processing circuit 14 (specifically by the first processing module 18). The processing circuit 14 can implement, for example, a control law with a feedback loop.

[0072] For example, the output voltage is regulated to remain at or near 20 volts. This exemplary value is not limiting, and other values ​​for the setpoint voltage can be selected depending on the desired application.

[0073] The diagnostic device 2 also includes a diagnostic module 20, which is configured to identify sensor faults based on a duty cycle calculated (or determined) by the second processing module 16.

[0074] It is worth noting that the duty cycle calculated by the second processing module 16 is a setpoint value and is recalculated regularly based on the voltage changes obtained at the output of the power supply circuit 12.

[0075] Preferably, the diagnostic module 20 is configured to compare the duty cycle calculated by the second processing module 16 with the theoretical duty cycle calculated using values ​​measured by the first set of current sensors 6. The theoretical duty cycle can be calculated by the processing circuit 8.

[0076] However, other methods can also be used.

[0077] The operation of diagnostic module 20 will be described in detail below.

[0078] The diagnostic device 2 also includes an alarm module 22, for example configured to issue an alarm when a comparison performed by the comparison module 20 results in the identification of a fault in one or more current sensors 10.

[0079] According to the example, alarm module 22 can be programmed to activate indicator lights located on the front panel of the electrical equipment and / or display messages on the human / machine interface of the electrical equipment, wherein the interface may include a display screen or a touch screen. Alarm module 22 can also be configured to send alarm messages to remote devices, for example, via a wired or radio telecommunications link.

[0080] For example, alarm module 22 may include or be connected to a human / machine interface, or network device, or radio frequency communication device (e.g., radio transmitter / receiver), or radio hub or network gateway, or programmable logic controller, and many other examples exist.

[0081] In addition to information about the existence of a fault, the alarm message generated by the alarm module 22 may also contain information about the nature of the fault or information about the identification of one or more current sensors 10 that are malfunctioning.

[0082] In many embodiments, the processing circuit 14 is implemented by one or more electronic circuits.

[0083] The functions of comparison 20 and alarm 22 can also be implemented by electronic circuitry, for example, by the same electronic circuitry as processing circuitry 14. Alternatively, the functions of comparison 20 and alarm 22 can be implemented by software.

[0084] The processing circuit 8 associated with the first set of current sensors 6 can also be implemented by the same electronic device as the processing circuit 14.

[0085] According to an exemplary embodiment, processing circuitry 14 includes a processor, such as a programmable microcontroller or microprocessor. The processor is coupled to computer memory, or to any suitable computer-readable data storage medium, which includes executable instructions and / or software code provided for implementing the method according to the invention when the processor executes these instructions.

[0086] According to a variant, the processing circuit 14 may include a processor (DSP), a reprogrammable logic component (FPGA), an application-specific integrated circuit (ASIC), or any equivalent element for processing signals.

[0087] However, other architectures can be used to implement processing modules 16 and 18.

[0088] Figure 2 An exemplary embodiment of the processing circuit 14 is shown.

[0089] In some embodiments, as described below, the electrical equipment may include an electronic control circuit, which is referred to herein by reference numeral 30.

[0090] In the illustrated embodiment, electronic control circuitry 30 is connected to the output of current sensor 10. For each current sensor 10, rectifier bridge 32 is connected to the output of the corresponding sensor 10. The corresponding output of rectifier bridge 32 is connected to a common point 34.

[0091] For example, rectifier bridge 32 forms part of power supply circuit 12.

[0092] The power switch described above (here marked T2 in the figure) also forms part of the power supply circuit 12.

[0093] Power switch T2 is connected between point 34 and the electrical ground (represented here as GND) of circuit 30.

[0094] The power switch T2 can be a transistor, such as a field-effect transistor. As a variation, other technologies can be used, such as bipolar transistors, isolated-gate bipolar transistors (IGBTs), or relays, and there are many other examples.

[0095] In the following text, power switch T2 will be referred to as "transistor T2".

[0096] The electronic control circuit 30 also includes the processor 36 as described above, which centralizes all data processing functions of the electrical equipment.

[0097] For example, the functions of processing circuit 14, as well as modules 20 and 22, are implemented here by circuit 30. However, this example is non-limiting, and other implementations are possible.

[0098] Furthermore, in the example shown, circuit 30 can implement other functions, such as protection functions, for example, to control the opening of the separable electrical contacts of the device to interrupt the current flow in the phase conductors Ip1, Ip2, Ip3, and IpN of the electrical facility 4. However, these additional functions can be omitted.

[0099] In many embodiments, the electronic control circuit 30 includes a conductor forming a power rail connected to an input point. This power rail... Figure 2 It is represented as VMITOP in Chinese.

[0100] Common point 34 is connected to the output of control circuit 12, which is connected here to the input of circuit 30.

[0101] The energy storage device Cm (capacitor) is connected between the power rail and ground GND. This energy storage device Cm can charge or discharge according to changes in the output voltage over time. For example, this helps to convert the current supplied by sensor 10 into a smooth power supply voltage.

[0102] In the example shown, diode D1 is connected to the power rail to prevent current from flowing back to transistor T2, thereby preventing the energy storage Cm from fully discharging.

[0103] The control electrode of transistor T2 is connected to the first output of processor 36, which is therefore configured to switch transistor T2 between its on and off states.

[0104] Generally, power rails are specifically configured to supply power to at least one or more components of electrical equipment (e.g., processor 36).

[0105] For example, such as Figure 2 As shown, the power input of the processor 36 is connected to the power rail via the second diode D2, resistor Rbo, and capacitor Cb.

[0106] More precisely, in the example shown, resistor Rbo and diode D2 are connected in series between the power rail and the auxiliary power input of processor 36. Capacitor Cb is connected between resistor Rbo and ground GND.

[0107] In some implementations, such as Figure 1 As shown, coil 38 can be connected in series with the second power switch T1.

[0108] Coil 38 is, for example, the coil of an electromagnetic actuator configured to switch electrical equipment, particularly to move separable electrical contacts to interrupt current in a phase conductor.

[0109] The power switch T1 can be a transistor, such as a field-effect transistor. As a variation, other technologies can be used, such as bipolar transistors or isolated-gate bipolar transistors (IGBTs), or any other suitable technology.

[0110] Here, the control electrode of transistor T1 is connected to another output (denoted as Trip) of processor 36, used to switch transistor T1 between its on and off states as needed. In the on state, transistor T1 allows current to flow through coil 38.

[0111] However, when the electrical equipment does not have any protection function, or when the control of the actuator is performed by a control circuit different from the processor 36, the transistor T1 and the coil 38 can be omitted.

[0112] In other embodiments, circuit 30 may include an auxiliary power supply circuit that includes an auxiliary power input V_AUX designed to receive a power supply voltage provided by an external power source.

[0113] When sensor 10 cannot provide sufficient voltage for processor 36 to operate normally, the auxiliary power supply circuit allows processor 36 to be powered.

[0114] Therefore, the auxiliary power supply circuit provides redundancy in the power supply of device 2 (especially in the power supply of processor 36).

[0115] Preferably, the auxiliary power supply circuit is connected to the power rail VMITOP (and thus to the processor 36) via a switch SW1 controlled by the processor 36.

[0116] For example, when a power failure is detected, processor 36 commands switch SW1 to close so as to connect an external power supply to power rail V_AUX (it should be understood that when circuit 20 is operating normally, the external power supply is preferably disconnected from power rail VMITOP).

[0117] However, the auxiliary input V_AUX is optional and may not be connected to a power supply, or may even be omitted from device 2. In this case, device 2 may still include an alternative power supply, such as a battery, connected to transistor 36.

[0118] However, in many embodiments, the auxiliary voltage input V_AUX and auxiliary circuitry can be omitted.

[0119] Generally, thanks to the processing circuit 14, the output voltage between the power rail and ground GND is regulated; in other words, the output voltage between the power rail and ground GND is kept more or less constant.

[0120] To this end, module 14 uses a measurement system to measure the voltage present on the power rail, such as a voltage divider bridge comprising two resistors Ra and Rb connected between the power rail and ground GND.

[0121] For example, processor 36 is connected to this voltage divider bridge via one of its input terminals.

[0122] The voltage measured by the measurement system can be converted into a digital signal, for example by means of an analog-to-digital converter, which is integrated into the processor 36, before being processed by the processor 36.

[0123] As a variant, the voltage measured by this measurement system can remain in analog form, with at least some of the subsequent processing operations performed by analog electronic components such as comparators.

[0124] Figure 4and 5 The changes in electrical quantities in device 2 are shown under the condition that the current sensor 10 is operating normally and under the condition that one of the current sensors 10 malfunctions.

[0125] exist Figure 4 In the first graph 50, the current from the current sensor 10 changes over time (horizontal axis, marked in seconds).

[0126] More precisely, curve 52 corresponds to the current measured at point 34, which is the result of the sum of the currents from each current sensor 10.

[0127] Curves 54, 55, and 56 correspond to each current from the current sensor 10 associated with phase conductors Ip1, Ip2, and Ip3 after rectification by rectifier bridge 32.

[0128] It can be observed that, when the line current is a sinusoidal AC current with a frequency of 50 Hz, curves 54, 55, and 56, showing the phases of the three-phase AC currents in phases Ip1, Ip2, and Ip3, have a period of 20 milliseconds and a phase angle shifted by 120 degrees relative to each other. The three current sensors 10 associated with these phase conductors operate normally.

[0129] Curve 52, corresponding to the rectified current, exhibits a stable value and may oscillate slightly within intervals of a predefined current value (e.g., up to 10% or 20% of its maximum amplitude).

[0130] Curve 58 shows the regulated voltage obtained at the output of power supply circuit 12.

[0131] Curve 60 shows the form of the control signal used to control power switch T2.

[0132] For example, the control signal can take two different values: a first value (value 0 on the vertical axis) for switching transistor T2 to the non-conducting state and a second value (value 1 on the vertical axis) for switching transistor T2 to the conducting state.

[0133] The control signal oscillates between two values, for example, with a periodicity that may vary depending on the current value from sensor 10. It should be understood that the duty cycle selected by processing module 18 (e.g., defined as the ratio between the time elapsed during each cycle of the second value and the total duration of that cycle) is therefore an image of the current measured by sensor 10.

[0134] In the example shown, the duty cycle is greater than or equal to 75% or equal to 80%. This example is not restrictive and other values ​​can be chosen as variations depending on the situation.

[0135] As can be seen from curves 58 and 60, when transistor T2 is in the on state, the output voltage decreases, while when transistor T2 is in the off state, the output voltage 58 increases.

[0136] For example, the output voltage 58 increases in the off state because the energy storage Cm is in the process of recharging. Conversely, the voltage 58 decreases in the on state because the energy storage Cm is discharging, and in particular because a portion of the stored energy is consumed to power the active electronic components of device 2 (e.g., processor 36).

[0137] In this example, due to regulation, voltage 58 is maintained between 20 volts and 21 volts.

[0138] Figure 5 A similar curve for the same device 2 is shown when one of the current sensors 10 malfunctions and stops supplying current.

[0139] In the example shown, the current sensor 10 associated with phase conductor Ip2 malfunctions and then stops delivering any current.

[0140] exist Figure 5 In the figure, graph 70 shows the change of current from current sensor 10 over time (horizontal axis, marked in seconds).

[0141] Curves 72, 74, and 76 in graph 70 correspond to respectively Figure 4 Curves 52, 54, and 56 in graph 50.

[0142] In contrast, graph 70 does not include any curves equivalent to curve 55, because the corresponding current sensor 10 has failed and no longer generates any current.

[0143] As a result, the total current (curve 72) has a lower amplitude and a much larger amplitude variation (e.g., up to 50% or more of the maximum amplitude).

[0144] To compensate for this change while continuing to provide output voltage regulation, processing module 18 automatically modifies the switching parameters of transistor T2, corresponding to the modification of the duty cycle. In fact, it should be understood that the duty cycle is the operating voltage of the controlled regulation closed loop, measured on a graph of the voltage across the power rail VMITOP, through a voltage divider bridge formed by resistors Ra and Rb.

[0145] Therefore, it can be seen from curves 78 and 80, which correspond to curves 58 and 60 respectively, that the duty cycle is reduced so as to allow the output voltage to remain in a form and amplitude that is close to or even the same as that presented in the normal condition (curve 60) when the current sensor 10 is operating normally.

[0146] By monitoring the switching duty cycle of transistor T2 (e.g., its value or its change over time), the occurrence of a fault in current sensor 10 can be detected.

[0147] This example is given for illustrative purposes and does not prevent embodiments of the invention from being implemented for detecting other types of faults in current sensors, such as simultaneous faults in multiple current sensors 10, or current sensors 10 transmitting incorrect values.

[0148] Now for reference Figure 3 An example describing the operation of diagnostic device 2.

[0149] Initially, with the aid of current sensor 10, the electrical equipment is operating and drawing at least a portion of its power from the current flowing in the line conductors. Control circuit 14 regulates the output voltage supplied by power supply circuit 12 by controlling one or more power switches (T2) with appropriate control signals.

[0150] During step S100, device 2 automatically determines (here via the second processing module 16) the duty cycle for controlling power supply circuit 12. Step S100 and the method can be triggered periodically.

[0151] During step S102, module 20 analyzes the determined duty cycle in order to identify faults from one of the current sensors 10.

[0152] If no fault condition is identified, the method then stops until the next execution of step S100.

[0153] In the opposite case, the fault condition is considered to be identified.

[0154] For example, during step S104, module 22 generates an alarm message.

[0155] Optionally, during step S106, the operation of all or part of the electrical equipment can be interrupted, for example by switching the electrical equipment to an electrically disconnected state, to avoid a situation where electrical faults in the facility can no longer be detected. In effect, electrical facility 4 will no longer be protected.

[0156] For example, for this purpose, a closing command can be sent to transistor T1 to power the actuator coil 38, thereby triggering the electrical device by opening its electrical contacts.

[0157] As a variation, these steps can be performed in a different order. Some steps may be omitted. In other embodiments, the described examples do not preclude other steps from being performed in conjunction with and / or sequentially with the described steps.

[0158] Generally, the diagnostic module 20 can be configured in various ways to analyze switching-related data of the power switch (especially the switching duty cycle of transistor T2).

[0159] According to one possibility, as mentioned above, the analysis can be performed directly using information about the switch duty cycle (step S100).

[0160] More generally, a numerical index representing the switch duty cycle can also be used, such as the average switch duty cycle, or any other suitable statistical representation.

[0161] For example, the numerical index representing the duty cycle value can be determined by the second processing module 16 during step S100, for example, by collecting multiple samples of the control signal over a predefined duration and then calculating the average value of the control signal. Therefore, this numerical index is the object of analysis (comparison) during step S102.

[0162] Averaging a set of values ​​obtained over a predefined time period (e.g., over a period corresponding to multiple cycles of current flowing in a phase conductor).

[0163] Furthermore, as mentioned earlier, the switching duty cycle can be estimated based on measured electrical quantities (such as the current flowing in the power switch or the average energy sampled in the energy storage Cm).

[0164] Regarding the analysis performed during step S102, it can be observed that, typically, if one of the current sensors 10 malfunctions, the input current at the input of the power supply circuit 12 is lower than the current when all current sensors 10 are operating normally. In fact, all other things being equal, the capacitor Cm will take longer to recharge.

[0165] Subsequently, module 18 will have to modify the switching parameters to continue adjusting the output voltage at the predefined setpoint value. This change will affect the form of the control signal, thus affecting the duty cycle.

[0166] In some embodiments, during analysis, the duty cycle can be compared with one or more reference values ​​to determine whether one or more current sensors 10 exhibit abnormal behavior that reveals a fault.

[0167] Based on the comparison results, fault conditions or other situations will be identified. For example, if the determined duty cycle differs significantly from the expected value, a fault condition will be considered identified.

[0168] For example, if the current sensor 10 is operating normally, a reference value can be defined based on the amount of current that the circuit 12 should theoretically receive.

[0169] A reference value can be selected from multiple predefined reference values ​​based on the amplitude of the current flowing in the phase conductor.

[0170] For example, multiple current intervals are predefined, each associated with a reference value. In practice, during operation, the current amplitude is measured by current sensor 6 or 10, and then one of these intervals is selected based on the measured amplitude to obtain the corresponding reference value.

[0171] For a given number of current sensors 10, these reference values ​​can come from a table pre-constructed by the builder of the device and correspond to known operating states, for example, obtained through calibration.

[0172] These reference values ​​and / or these tables can be stored in the memory of the processing circuit 14.

[0173] Optionally, the analysis may include an analysis of the duty cycle over time, for example, to detect abnormal changes that indicate a change in the amount of current received at the input of power supply 2 relative to historical values ​​(duty cycle values ​​at previous times).

[0174] This analysis of time-varying changes can be performed using an infinite impulse response filter or a recursive impulse filter implemented by device 2.

[0175] As a variation, machine learning systems (such as classification systems pre-programmed by a learning phase) can be used to perform analyses that change over time.

[0176] The system can be implemented by device 2 and can be based on a learning database, which can be stored in the memory of device 2 or in a remote database accessible via a communication link.

[0177] According to other embodiments, the analysis may take into account the current values ​​measured independently by the first set of current sensors 6, or even the measurement information from the processing circuit 8 and indirectly from these same sensors 6.

[0178] For example, module 20 can be configured to compare the duty cycle determined by module 18 with a theoretical exponent calculated using the current values ​​measured by the first set of current sensors 6.

[0179] For example, the determination of the theoretical index can be based on the manufacturing of multiple products, each constructed to represent production tolerances (minimum / maximum products). In each of these products, a fault of one or more power sensors is forced or simulated, and a picture of the duty cycle is recorded. Based on these records, an acceptable range is generated according to one or more measured current values. Devices whose duty cycles are outside the thus generated range are considered faulty and generate an alarm signal.

[0180] This is especially helpful in identifying faulty current sensors.

[0181] With the aid of the present invention, the diagnostic device 2 according to various embodiments allows the detection of operational anomalies in one of the current sensors 10 that may jeopardize the proper operation of electrical equipment.

[0182] This detection is achieved, for example, by simply using the existing architecture of electrical equipment (sensors and processing circuitry) and based on information further measured by control circuitry.

[0183] Therefore, this detection is easier to implement than a detailed analysis of the electrical quantities measured by each current sensor 10.

[0184] Optionally, comparing measurement data from the first set of sensors 6 and from the processing circuit 8 allows for more detailed diagnostics and, in particular, allows for the identification of one or more current sensors 10 that are malfunctioning.

[0185] Figure 6 It shows Figure 2 Another embodiment of the circuit.

[0186] In this new embodiment, circuit 30 is replaced by circuit 90, which is largely similar to, or even identical to, circuit 30, but differs from circuit 30 in that it includes a measuring resistor (denoted as R) connected between transistor T2 and ground GND. shunt ), and coupled to the measuring resistor R shunt Measurement circuit 24.

[0187] The measuring circuit 24 and the measuring resistor R shunt This allows measurement of the current flowing through transistor T2 when it is in the ON state, thereby obtaining an image of the total current supplied by current sensor 10 at common connection point 34. This current corresponds here to the current supplied by... Figure 3 and 4 The current is depicted by curves 52 and 72 in the figure.

[0188] In this embodiment, the diagnostic module 20 is programmed to detect fault conditions by comparing the current from the second set of sensors 10 (i.e., sensors for power supply) with the current from the first set of current sensors 6 (measuring sensors), and then using the value and / or waveform of the current from the current sensors 6 as a reference for the comparison.

[0189] Therefore, if the current from sensor 10 is different from the reference current from sensor 6 (e.g., if the amplitude shows a difference greater than a predefined threshold relative to the reference value), the diagnostic module 20 identifies the difference and automatically determines that at least one of the second set of sensors 10 is malfunctioning.

[0190] In some variations, the measurement circuit 24 may be integrated into the processing circuit 8, or at least partially implemented by the processing circuit 8.

[0191] According to yet another embodiment that can be implemented independently of all or part of the embodiments described above, a fault detection method based on the comparison of current from sensor 10 and current from sensor 6 can be used to replace the duty cycle-based analysis method described above.

[0192] In other words, the fault condition is then detected simply by comparing the current from sensor 10 with the reference current from sensor 6, instead of using the duty cycle.

[0193] In this case, the method for identifying the current sensor includes the following steps:

[0194] The current from current sensor 6 in the first set of sensors is measured in order to obtain the value of the reference current;

[0195] The current from the current sensor 10 in the second set of sensors is measured;

[0196] The current from current sensor 10 is compared with a reference value;

[0197] If the current from current sensor 10 differs from the reference value (e.g., greater than a predefined difference), a fault condition is identified.

[0198] These steps can be repeated over time, for example, periodically or continuously.

[0199] Any feature of one of the embodiments or variations described above may be implemented in the other embodiments and variations described.

Claims

1. A method for identifying faulty current sensors in electrical equipment, wherein the power supply for the electrical equipment is provided at least in part by a switch-mode power supply circuit (12) connected to at least one current sensor (10), the at least one current sensor sampling the current in the phase conductor of the electrical installation (4), the power supply circuit delivering a regulated voltage (VMITOP), wherein the method comprises the following steps: - Determine the switching duty cycle of the power switch of the switching mode power supply (S100); -Analyze the switch duty cycle determined by (S102); - If the behavior of the switch duty cycle represents a fault in at least one of the current sensors, then identify the fault condition (S104). The analysis of the switch duty cycle includes a historical analysis of the change of the duty cycle over time relative to past values, and the analysis of the change over time is performed using an infinite impulse response filter.

2. The method according to claim 1, wherein the analysis of the switch duty cycle (S102) includes comparing the determined switch duty cycle with a predetermined reference value.

3. The method of claim 2, wherein the predetermined reference value is selected based on the amplitude of the current flowing in the phase conductor.

4. The method according to claim 1, wherein the analysis (S102) of the switch duty cycle includes comparing the determined switch duty cycle with a theoretical value of a comparison duty cycle calculated based on current values ​​measured by one or more additional current sensors (6).

5. The method according to any one of claims 1-4, wherein the determined duty cycle (S100) is the average value of the switching duty cycles averaged over a predefined time period.

6. The method according to any one of claims 1-4, wherein if a fault condition is identified, an alarm is automatically issued (S104).

7. The method according to any one of claims 1-4, wherein, The electrical equipment is an electrical protection device, and the device is automatically triggered if a fault condition is detected (S106).

8. The method according to any one of claims 1-4, wherein the method for identifying faulty sensors further comprises the step of: -Measure the total current flowing in one or more phase conductors of the electrical facility (4) by means of one or more additional current sensors (6); - Measure the total current from the at least one current sensor (10), and then compare the measured total current value with the current value measured by the one or more additional sensors (6); - If the difference between the total current value from the at least one current sensor (10) and the current value measured by the one or more additional sensors (6) is greater than a predefined threshold, a fault condition is identified.

9. The method according to claim 5, wherein, The predefined time period is a time period corresponding to multiple cycles of the current flowing in the phase conductor.

10. The method according to claim 7, wherein, The electrical protection device is a circuit breaker.

11. An electrical device comprising: - At least one current sensor (10) is designed to sample the current in the phase conductor of the electrical installation (4), and - A switch-mode power supply circuit (12) is connected to the current sensor and configured to deliver a regulated voltage for supplying power to the electrical equipment. The electrical equipment includes a diagnostic device (2) configured to perform the following steps: - Determine the switching duty cycle of the power switch of the switching mode power supply (S100); -Analyze the switch duty cycle determined by (S102); - If the behavior of the switch duty cycle represents a fault in at least one of the current sensors, then identify (S104) the fault condition. The analysis of the switch duty cycle includes a historical analysis of the change of the duty cycle over time relative to past values, and the analysis of the change over time is performed using an infinite impulse response filter.

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