SHORT CIRCUIT DETECTION DEVICE

Abstract

SHORT CIRCUIT DETECTION DEVICE The present description relates to a device (100) for detecting a short circuit in a direct current circuit comprising a voltage source (102), a bus comprising at least two conductive elements (104, 106) each coupled to one of the terminals of the voltage source, first and second thyristors (112, 114) coupled to the voltage source and to the bus, and at least one capacitive element forming a storage capacitor (118) each of whose electrodes is coupled to one of the two conductive elements of the bus, the short circuit detection device comprising at least one control circuit (124) configured to control the polarizations and the operating regimes of the first and second thyristors such that a short circuit detection phase is implemented before a precharge of the storage capacitor. Figure for the abstract: Fig. 1

Description

Title of the invention: SHORT CIRCUIT DETECTION DEVICE Technical field

[0001] The present description relates generally to a short circuit detection device. Prior art

[0002] In a direct current circuit, for example present in an electric vehicle, the vehicle battery is connected to a bus comprising two conductive elements, each coupled to one of the terminals of the battery. The capacitive elements of the circuit coupled to the bus can be likened to a storage capacitor, or "bulk capacitor" in English, coupled in parallel to the battery via the conductive elements of the bus and relays making it possible to connect and disconnect the battery from the bus.

[0003] When the relays are closed to connect the bus to the battery, a significant inrush current flows between the battery and the storage capacity. To avoid the occurrence of this inrush current, the storage capacity is generally precharged with a precharge current before the relays are closed. For this, it is possible to couple, in parallel with one of the relays, a precharge circuit comprising a precharge resistor and a switch. The precharge of the storage capacity is implemented by turning on this switch and keeping open the relay which is coupled in parallel to the precharge circuit, the other relay being closed. This precharge phase is implemented for a sufficient duration to obtain, at the terminals of the storage capacity, the desired precharge voltage.

[0004] If a short circuit is present in the DC circuit, a very large current flows through the switch and can damage other elements coupled to the bus. When the switch of the precharge circuit corresponds to a thyristor, blocking the thyristor to stop this short-circuit current requires the use of an additional circuit.

[0005] When the precharge circuit switch corresponds to a relay, it is possible to simply open the relay to stop the short-circuit current. However, given the time required for the relay to open and the phenomena of rebounds and electric arcs, the short-circuit current can damage, during this time, the other elements coupled to the bus. In addition, this relay opening time increases with time. Summary of the invention

[0006] There is a need to provide a solution to address the problems encountered with existing solutions.

[0007] A particular embodiment addresses at least some of these problems and proposes a device for detecting a short circuit in a direct current circuit comprising at least one voltage source, a bus comprising at least two conductive elements each coupled to one of the terminals of the voltage source, first and second thyristors coupled to the voltage source and to the bus, and at least one capacitive element forming a storage capacitor each of whose electrodes is coupled to one of the two conductive elements of the bus,

[0008] the short-circuit detection device comprising at least one control circuit configured to control the polarizations and the operating regimes of the first and second thyristors such that: • during a short-circuit detection phase, the first thyristor is put in the blocked state and the second thyristor is reverse-biased and conducts a non-zero reverse current charging the storage capacity, then a voltage across the storage capacity is determined; then • if the voltage determined across the storage capacity is less than or equal to a short-circuit threshold value, the first and second thyristors are blocked, or if the voltage determined across the storage capacity is greater than the short-circuit threshold value, the storage capacity is precharged by blocking the second thyristor and turning on the first thyristor (112).

[0009] In a particular embodiment, the short-circuit threshold value is equal to 0.

[0010] In a particular embodiment, the short-circuit detection device is such as : • the voltage source is a direct voltage source comprising at least one battery; • the direct current circuit comprises at least a first switch coupling a positive terminal of the battery to a first of the two conductive elements of the bus, and at least a second switch coupling a negative terminal of the battery to a second of the two conductive elements of the bus; • at least one of the first and second switches corresponds to a relay; • the direct current circuit includes a discharge circuit of the capacity of storage including at least one third switch coupled in series to at least one discharge resistor, the discharge circuit being coupled in parallel with the storage capacitor; • the first thyristor is part of a pre-charging circuit further including a pre-charging resistor coupled in series with the first thyristor, the pre-charging circuit precharge being coupled in parallel with one of the first and second switches and such that the cathode of the first thyristor is coupled to the negative terminal of the battery or the anode of the first thyristor is coupled to the positive terminal of the battery; • the second thyristor is coupled in parallel with one of the first and second switches and such that the anode of the second thyristor is coupled to the negative terminal of the battery or the cathode of the second thyristor is coupled to the positive terminal of the battery.

[0011] In a particular embodiment, the short-circuit detection device is such that: • the control circuit is configured to apply control signals to the gates of the first and second thyristors, or • the short-circuit detection device further comprises a Zener diode and an RC circuit, the anode of the Zener diode being coupled to the gate of the first thyristor, the cathode of the Zener diode being coupled to the anode of the second thyristor and to a first terminal of the RC circuit, a second terminal of the RC circuit being coupled to the cathode of the first thyristor.

[0012] In a particular embodiment, the control circuit is configured to: • before the short-circuit detection phase, close the first switch, then carry out an initial measurement of the voltage across the storage capacitor; then • implement the short-circuit detection phase if the voltage initially measured at the terminals of the storage capacity is less than or equal to the short-circuit threshold value, or directly pre-charge the storage capacity if the voltage initially measured at the terminals of the storage capacity is greater than the short-circuit threshold value.

[0013] In a particular embodiment, when the anode of the second thyristor is coupled to the negative terminal of the battery, the control circuit is configured to control the first switch such that it is conductive during the short-circuit detection phase and during the precharging of the storage capacity.

[0014] In a particular embodiment, the control circuit is configured such that, after precharging the storage capacity, the first and second switches are put into the on state and the first and second thyristors are blocked.

[0015] In a particular embodiment, the third switch is a third thyristor, and the control circuit is configured to apply a control signal to the gate of the third thyristor.

[0016] In a particular embodiment, during a phase of disconnection of the battery from the bus implemented after the precharging of the storage capacity, the control circuit is configured to turn on the third switch after opening the first and second switches.

[0017] In a particular embodiment, when determining the voltage across the terminals of the storage capacitor implemented during the short-circuit detection phase, the control circuit is configured to block the second thyristor.

[0018] Another particular embodiment provides a vehicle battery monitoring system, comprising at least one short circuit detection device as proposed above.

[0019] Another particular embodiment proposes an electrical power converter comprising at least one short-circuit detection device as proposed above.

[0020] In a particular embodiment, the first and second thyristors are part of the switching cells of the electrical power converter. Brief description of the drawings

[0021] These characteristics and advantages, as well as others, will be explained in detail in the following description of particular embodiments given without limitation in relation to the attached figures among which:

[0022] - [Fig.l] schematically represents a first example of the realization of a short circuit detection device according to a particular embodiment;

[0023] - [Fig.2] and [Fig.3] represent timing diagrams of signals of the device of short circuit detection according to the first embodiment;

[0024] - [Fig.4] schematically represents a second example of the embodiment of a short circuit detection device according to a particular embodiment;

[0025] - [Fig.5] represents a timing diagram of signals from the detection device of short circuit according to the second embodiment example;

[0026] - [Fig.6] schematically represents an example of the embodiment of a converter power comprising a short-circuit detection device according to a particular embodiment. Description of the embodiments

[0027] The same elements have been designated by the same references in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same references and may have identical structural, dimensional and material properties.

[0028] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been shown and are detailed. In particular, different elements (voltage source, bus, thyristor, control circuit, etc.) of the short-circuit detection device are not detailed. Those skilled in the art will be able to to carry out these elements in detail from the functional description given here.

[0029] Unless otherwise specified, when referring to two elements connected to each other, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") to each other, this means that these two elements can be connected or be connected by means of one or more other elements.

[0030] Unless otherwise specified, the expressions "about", "approximately", "substantially", and "of the order of" mean to within 10%, preferably to within 5%.

[0031] Furthermore, the signals of the timing diagrams of Figures 2, 3 and 5 are represented schematically and not to scale relative to each other, both for the amplitudes and for the durations of the different parts of these signals. Thus, the signals symbolically represented in the form of square waves in these figures may correspond to pulse signals or other forms of signals.

[0032] A first example of embodiment of a short-circuit detection device 100 is described below in connection with [Fig.l].

[0033] In this first exemplary embodiment, the device 100 makes it possible to detect a short circuit in a direct current circuit forming, for example, part of a vehicle battery control system such as an electric car, before the battery is connected to the bus of the direct current circuit of the vehicle.

[0034] The direct current circuit comprises at least one voltage source 102 which, in this first embodiment, corresponds to a direct voltage source comprising at least one battery and delivering a direct current. By way of example, the voltage delivered to the terminals of the battery is for example of the order of 400 V or 800 V.

[0035] The direct current circuit also comprises a bus comprising at least two conductive elements 104, 106 each coupled to one of the terminals of the voltage source 102. In the first exemplary embodiment described, the first conductive element 104 is coupled to the positive terminal of the voltage source 102 through a first switch 108, and the second conductive element 106 is coupled to the negative terminal of the voltage source 102 through a second switch 110.

[0036] In this first exemplary embodiment, at least one of the first and second switches 108, 110 corresponds to a relay in order to be able to physically cut off the voltage source 102 from the bus, without parasitic leakage current. In the example of [Fig.l], the two switches 108, 110 correspond to relays. Alternatively, one of the two switches 108, 110 may not be a relay and may correspond for example to a semiconductor device such as a power transistor or any other electronic component suitable for forming such a switch.

[0037] The device 100 also comprises first and second thyristors 112, 114 coupled to the voltage source 102 and the bus.

[0038] In the first described embodiment, the first thyristor 112 is part of a precharge circuit further including a precharge resistor 116 coupled in series with the first thyristor 112. The precharge circuit is coupled in parallel with one of the first and second switches 108, 110 (in parallel with the second switch 110 in the example of [Fig. 1]). In addition, in the example of [Fig. 1], the cathode of the first thyristor 112 is coupled to the negative terminal of the voltage source 102. Alternatively, the precharge circuit may be coupled in parallel with the first switch 108, with in this case the anode of the first thyristor 112 being coupled to the positive terminal of the voltage source 102.

[0039] In the example of [Fig.l], the second thyristor 114 forms a short-circuit detection circuit coupled in parallel with one of the first and second switches 108, 110. In the example of [Fig.l], the second thyristor 114 is coupled in parallel with the second switch 110. In addition, the anode of the second thyristor 114 is coupled to the negative terminal of the voltage source 102. Alternatively, the second thyristor 114 may be coupled in parallel with the first switch 108, with in this case the cathode of the second thyristor 114 being coupled to the positive terminal of the voltage source 102.

[0040] In the particular embodiment described, the direct current circuit comprises one or more capacitive elements together forming a storage capacitor 118, each of the electrodes of which is coupled to one of the two conductive elements 104, 106 of the bus.

[0041] In the exemplary embodiment described, the device 100 also comprises a circuit for discharging the storage capacitor 118 including at least a third switch 120 coupled in series to a discharge resistor 122. This discharge circuit is coupled in parallel with the storage capacitor 118. In the exemplary embodiment shown in [Fig.l], the third switch 120 corresponds to a third thyristor.

[0042] The device 100 also comprises at least one control circuit 124, comprising for example at least one microcontroller, configured to control the polarization of the first, second and third thyristors 112, 114, 120, in particular by means of the opening or closing command of each of the first and second switches 108, 110, as well as the operating regimes of the first, second and third thyristors 112, 114, 120. In the first exemplary embodiment described, the operating regimes of the first, second and third thyristors 112, 114 and 120 are controlled by means of control signals applied to the triggers of the thyristors 112, 114, 120 by the control circuit 124. In [Fig.l], a control signal “CTRL1” is applied to the trigger of the first thyristor 112, a control signal “CTRL2” is applied to the trigger of the second thyristor 114 and a control signal “CTRL3” is applied to the trigger of the third thyristor 120. In [Fig.l], the electrical connections between the switches 108, 110 and the control circuit 124 and between the thyristors 112, 114, 120 and the control circuit 124 are not shown.

[0043] In the particular embodiment described, the device 100 also comprises a voltage divider bridge coupled to the conductive elements 104, 106 of the bus, in parallel with the storage capacitor 118. In the example of [Fig.l], this voltage divider bridge comprises two resistors 126, 128. The voltage measured at the terminals of one of the resistors 126, 128 makes it possible, by knowing the values ​​of the resistors 126, 128, to determine the value of the voltage at the terminals of the storage capacitor 128, i.e. the voltage on the direct current bus.

[0044] Furthermore, in the example of [Fig.l], the gates of the first and second thyristors 112, 114 are coupled to resistors through which the control signals are applied.

[0045] Although not shown, a fuse may be present between the voltage source 102 and the bus. In addition, other components or circuits, such as for example power converters, may also be connected to the bus, these elements not being shown in the various figures.

[0046] An example of a method implemented by the device 100 previously described in connection with [Fig.l] is described below. [Fig.2] represents examples of control and measurement signals obtained during this method which corresponds to a method of connecting the voltage source 102 to the bus, with a prior verification of the presence of a short circuit on the direct current circuit. [Fig.3] represents these same signals when a short circuit is detected on the circuit, leading to the voltage source 102 being kept not connected to the bus.

[0047] In Figures 2 and 3, a high value of the signals “RELAY1” and “RELAY2” represents a command to close the switches 108, 110 and a low value of these signals represents a command to open these switches 108, 110. In addition, a high value of the signals “CTRL1” and “CTRL2” represents a command to turn on the thyristors 112, 114 and a low value of these signals represents a command to block these thyristors 112, 114.

[0048] In the exemplary embodiment described, in the initial state of this method, the first and second switches 108, 110 are open and the first, second and third thyristors 112, 114, 120 are blocked.

[0049] In a first phase of the method, which corresponds to the duration from time t0 to time ti visible in figures 2 and 3, the control circuit 124 sends to the first switch 108 a first control signal, called “RELAY 1” in the figures 2 and 3, ordering its closure.

[0050] In this example, the voltage across the storage capacitor 118 is determined during this first phase, for example from a measurement of the voltage across one of the resistors 126, 128, and compared to a short-circuit threshold value. This short-circuit threshold value is for example equal to 0 and defines a limit such that if, during this first phase, the voltage across the storage capacitor 118 is greater than this threshold value, this means that a short circuit is not present in the direct current circuit. The method can then directly move on to the pre-charging phase of the storage capacitor 118 described later.

[0051] If, during this first phase of the method, the voltage across the storage capacitor 118 remains lower than or equal to this threshold value, this means that the storage capacitor 118 is not electrically charged or that a short circuit is present in the direct current circuit. In the examples of FIGS. 2 and 3, the voltage across the storage capacitor 118, called “VC1”, remains zero even after closing the first switch 108, which means that a short circuit may be present in the direct current circuit. A short circuit detection phase is implemented in this case.

[0052] The short-circuit detection phase is implemented between the times ti and t2 visible in Figures 2 and 3. During this phase, the first thyristor 112 is blocked (in Figures 2 and 3, the control signal “CTRL2” sent by the control circuit 124 to the trigger of the first thyristor 112 remains zero) and the second thyristor 114, which is reverse-biased, conducts a non-zero reverse current for the duration t2 - tb This conduction of a reverse current by the second thyristor 114 is obtained thanks to its reverse bias and the application, by the control circuit 124, of a current to the trigger of the second thyristor 114 which generates this conduction. The value of the reverse conduction current obtained is proportional to the value of the current applied to the trigger of the second thyristor 114, the value of the coefficient of proportionality [3 between these two currents being a function of the characteristics of the second thyristor 114.For example, the current applied to the trigger of the second thyristor 114 may be of the order of 16 mA, or more generally between 10 mA and 16 mA in order to obtain a reverse conduction current between 6 mA and 10 mA.

[0053] In [Fig.2], the circulation of this weak reverse current through the second thyristor 114 causes a slow charging of the storage capacitor 118, and therefore a weak increase in the voltage across the terminals of the storage capacitor 118. For example, this weak increase in the voltage across the terminals may be equal to 10 V, or more generally between 1% and 5% of the battery voltage. In [Fig.3], the circulation of this weak reverse current through the second thyristor 114 does not charge the storage capacity 118 due to the presence of a short circuit in the direct current circuit. This voltage is determined, for example, by a measurement on the voltage divider bridge, then compared to the short circuit threshold value.

[0054] The duration t of this short-circuit detection phase can be expressed by the following equation:

[0055] [Math.l] t=CX

[0056] with C the value of the storage capacity 118, AV the increase in the voltage across the storage capacity 118, and IR the reverse conduction current charging the storage capacity 118. For example, for a current IR equal to 16 mA, a capacity C of 0.67 mF and an increase in voltage AV of 10 V, the duration t is equal to 425 ms.

[0057] If the determined voltage is less than or equal to the short-circuit threshold value, for example equal to 0 in the example described here, the first and second thyristors 112, 114 are blocked, and the method ends since this means that a short-circuit is indeed detected in the direct current circuit. The voltage source 102 is, in this case, not connected to the bus. This scenario corresponds to that shown in [Fig. 3], in which the voltage VC1 is zero at time t2. In the presence of a short-circuit, the first switch 108 is then open (signal “RELAY 1” changing to the low value from t2).

[0058] If the determined voltage is higher than the short-circuit threshold value, as is the case in the timing diagram of [Fig.2], a pre-charging phase of the storage capacitor 118 is implemented. The second thyristor 114 is blocked (signal "CTRL2" going to the low value) and the first thyristor 112, which is forward-biased, is put into the on state by the control circuit 124 which applies, to the trigger of the first thyristor 112, the signal "CTRL1" of high value. The storage capacitor 118 then charges more quickly than during the short-circuit detection phase because the current flowing through the storage capacitor 118 is limited only by the pre-charging resistor 116, and no longer by the reverse conduction of the second thyristor 114.

[0059] The instant t3 visible in [Fig.2] corresponds to the instant from which the desired precharge voltage value is reached at the terminals of the storage capacitor 118. For example, this desired precharge voltage value may be between 80% and 90% of the voltage at the terminals of the voltage source 102. The command applied to the trigger of the first thyristor 112 is then removed (signal "CTRL1" going to the low value) and the second switch 110 is closed. The first thyristor 112 then naturally goes to the blocked state because the current will then pass through the second switch 110 instead of the first thyristor 112, thus connecting the voltage source 102 to the bus (the first switch 108 remains closed after time t3)•

[0060] Thus, by controlling the various elements of the device 100 as described above, the current flowing in the bus is monitored before the start of the precharging of the storage capacitor 118, which makes it possible to avoid the implementation of such a precharging if a short circuit is detected on the bus. In addition, the integrity of any fuse present between the voltage source 102 and the bus is preserved.

[0061] When the voltage source 102 must be disconnected from the bus, for example when stopping the vehicle, after (or even during) the precharging of the storage capacitor 118, the control circuit 124 puts the third thyristor 120 into the on state and opens the first and second switches 108, 110. The storage capacitor 118 then discharges through the discharge resistor 122 which limits the value of the current during this discharge phase.

[0062] A second example of embodiment of a short-circuit detection device 100 is described below in connection with [Fig.4].

[0063] The device 100 according to the second exemplary embodiment comprises all the elements of the device 100 according to the first exemplary embodiment previously described in connection with [Fig.l].

[0064] In addition to these elements, the device 100 according to this second exemplary embodiment comprises a Zener diode 130 whose anode is coupled to the trigger of the first thyristor 112. The cathode of the Zener diode 130 is coupled to a terminal of an RC circuit comprising a resistor 132 and a capacitor 134 and to the anode of the second thyristor 114. A second terminal of the RC circuit is coupled to the cathode of the first thyristor 112.

[0065] A timing diagram of the signals of the device 100 according to the second exemplary embodiment, during a short-circuit detection prior to a connection of the voltage source 102 to the bus, is shown in [Fig.5].

[0066] On this timing diagram, the different signals represented correspond to those previously described in connection with figures 2 and 3, except for the signal “VC2” which corresponds to the voltage across the terminals of the Zener diode 130.

[0067] Between times 0 and tb, that is to say during the initial measurement of the voltage across the storage capacitor 118, the voltage across the Zener diode 130 remains zero. The other signals are similar to those previously described in connection with FIGS. 2 and 3. As previously, if the voltage across the storage capacitor 118 which is determined during this first phase is greater than the short-circuit threshold, this means that a short-circuit is not present in the direct current circuit. The method can then proceed directly to the pre-charge phase. of the storage capacity 118. If, on the other hand, this voltage remains lower than or equal to this threshold value, this means that the storage capacity 118 is not electrically charged or that a short circuit is present in the direct current circuit. In this case, the process does not move on to the pre-charge phase and signals the detection of a possible short circuit.

[0068] Between the instants ti and t2 (short-circuit detection phase), the second thyristor 114 is reverse-biased and conducts a low reverse conduction current slowly charging the storage capacitor 118. This reverse conduction current also charges the capacitor 134, thus increasing the voltage VC2 across the Zener diode 130. The voltage across the capacitor 118 is then determined and if it is greater than the short-circuit threshold, the pre-charging phase of the storage capacitor 118 begins. If it is less than or equal to the short-circuit threshold, the second thyristor 114 is blocked and the switches 108, 110 are open.

[0069] In the example of [Fig.5], at time t2, the precharging phase of the storage capacitor 118 begins. The first thyristor 112 is put into the on state via the control signal automatically applied to the trigger of the first thyristor 112 by the Zener diode 130 thanks to the increase in the voltage obtained at the terminals of the Zener diode 130 during the short-circuit detection phase. The instant t3 symbolically represents the transition to the blocked state of the second thyristor 114. If a short circuit had been present in the circuit, the control signal applied to the trigger of the second thyristor 114 is removed before the voltage across the capacitor 134 reaches the value of the threshold voltage of the Zener diode 130 in order to avoid triggering, and therefore switching on, of the first thyristor 112.

[0070] The instant t4 visible in [Fig.5] corresponds to the instant from which the desired precharge voltage value is reached at the terminals of the storage capacitor 118. The second switch 110 is then closed, thus connecting the voltage source 102 to the bus (the first switch 108 remains closed after the instant t4).

[0071] As in the first exemplary embodiment previously described, by controlling the different elements of the device 100 according to the second exemplary embodiment, the current flowing in the bus is therefore monitored before the start of the precharging of the storage capacity 118 which is triggered automatically, and avoids the implementation of such a precharging if a short circuit is detected on the bus.

[0072] As in the first embodiment, when the voltage source 102 must be disconnected from the bus, the control circuit 124 opens the first and second switches 108, 110, then turns on the third thyristor 120. The storage capacitor 118 then discharges through the discharge resistor 122.

[0073] The different variants previously described in connection with the first example of embodiment of the device 100 can also be applied to the second example of implementation of device 100.

[0074] The short-circuit detection device 100, described above in the context of a vehicle battery control system 1000, is based on the use of a reverse-biased thyristor conducting a non-zero reverse current during a short-circuit detection phase to increase the voltage across the storage capacitor coupled to the bus and checks for the presence or absence of a short circuit before triggering the pre-charging of the storage capacitor in the absence of a detected short circuit.

[0075] Such a device 100 can also be applied within an electrical power converter 2000. An example of such a converter 2000 is described below in connection with [Fig.6].

[0076] In the example of [Fig.6], the converter 2000 is a power converter with power factor correction of the bidirectional totem pole type, or “bidirectional totem pole PFC” (PFC for “Power factor Corrector”), and allows a conversion or an adaptation of an alternating voltage to a direct voltage, or conversely a conversion or an adaptation of a direct voltage to an alternating voltage.

[0077] In this exemplary embodiment, the voltage source 102 corresponds to an alternating voltage source, one of the terminals of which is coupled to an inductive element 202. The converter 200 further comprises switching cells formed by two transistors 204, 206 and four thyristors 208, 210, 212 and 214. The switching arms of the converter 2000 are coupled in parallel with the storage capacitor 118. The control circuit 124, controlling in particular the switching of the transistors and thyristors of the converter 2000, is not visible in this [Fig.6].

[0078] When the converter 2000 performs a conversion or an adaptation of an alternating voltage to a direct voltage, the components used for the switchings are the transistors 204, 206 and the first two thyristors 208, 210. When the converter 2000 performs a conversion or an adaptation of a direct voltage to an alternating voltage, the components used for the switchings are the transistors 204, 206 and the other two thyristors 212, 214.Thus, in both cases, the two thyristors not used for switching are controlled by the control circuit 124 in a manner analogous to the first and second thyristors 112, 114 as previously described for the vehicle battery control system 1000, i.e. using the thyristor which is reverse biased to perform reverse conduction charging the storage capacitor 118, then the other forward biased thyristor to then perform the precharge of the storage capacitor 118 if the voltage across the storage capacitor 118 is greater than the short-circuit threshold.

[0079] The device 100 can be used for other types of power converter, such as unidirectional converters such as a converter integrating a mixed bridge coupled with a “Boost” type circuit.

[0080] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will occur to those skilled in the art.

[0081] Finally, the practical implementation of the embodiments and variants described is within the reach of those skilled in the art from the functional indications given above.

Claims

Claims

1. Device (100) for detecting a short circuit in a direct current circuit comprising at least one voltage source (102), a bus comprising at least two conductive elements (104, 106) each coupled to one of the terminals of the voltage source (102), first and second thyristors (112, 114) coupled to the voltage source (102) and to the bus, and at least one capacitive element forming a storage capacitor (118) each of whose electrodes is coupled to one of the two conductive elements (104, 106) of the bus, the short circuit detection device (100) comprising at least one control circuit (124) configured to control the polarizations and the operating regimes of the first and second thyristors (112, 114) such that: • during a short circuit detection phase,the first thyristor (112) is put in the blocked state and the second thyristor (114) is reverse biased and conducts a non-zero reverse current charging the storage capacitor (118), then a voltage across the storage capacitor (118) is determined; then • if the voltage determined across the storage capacitor (118) is less than or equal to a short-circuit threshold value, the first and second thyristors (112, 114) are blocked, or if the voltage determined across the storage capacitor (118) is greater than the short-circuit threshold value, the storage capacitor (118) is precharged by blocking the second thyristor (114) and turning on the first thyristor (112).,

2. A short circuit detection device (100) according to claim 1, wherein the short circuit threshold value is equal to 0.

3. Short-circuit detection device (100) according to one of the preceding claims, in which: • the voltage source (102) is a direct voltage source comprising at least one battery; the direct current circuit comprises at least a first

4. switch (108) coupling a positive terminal of the battery to a first of the two conductive elements (104) of the bus, and at least one second switch (110) coupling a negative terminal of the battery to a second of the two conductive elements (106) of the bus; • at least one of the first and second switches (108, 110) corresponds to a relay; • the direct current circuit comprises a discharge circuit for the storage capacity (118) including at least one third switch (120) coupled in series to at least one discharge resistor (122), the discharge circuit being coupled in parallel with the storage capacity (118); • the first thyristor (112) is part of a precharge circuit further including a precharge resistor (116) coupled in series with the first thyristor (112), the precharge circuit being coupled in parallel with one of the first and second switches (108, 110) and such that the cathode of the first thyristor (112) is coupled to the negative terminal of the battery or the anode of the first thyristor (112) is coupled to the positive terminal of the battery; • the second thyristor (114) is coupled in parallel with one of the first and second switches (108, 110) and such that the anode of the second thyristor (114) is coupled to the negative terminal of the battery or the cathode of the second thyristor (114) is coupled to the positive terminal of the battery. A short circuit detection device (100) according to claim 3, wherein: • the control circuit (124) is configured to apply control signals to the gates of the first and second thyristors (112, 114), or • the short-circuit detection device (100) further comprises a Zener diode (130) and an RC circuit (132, 134), the anode of the Zener diode (130) being coupled to the trigger of the first thyristor (112), the cathode of the Zener diode (130) being coupled to the anode of the second thyristor (114) and to a first terminal of the RC circuit (132, 134), a second terminal of the RC circuit (132, 134) being coupled to the cathode of the first thyristor (112).

5. Short-circuit detection device (100) according to one of claims 3 or 4, wherein the control circuit (124) is configured to: • before the short-circuit detection phase, close the first switch (108), then carry out an initial measurement of the voltage across the terminals of the storage capacitor (118); then • implement the short-circuit detection phase if the voltage initially measured across the terminals of the storage capacitor (118) is less than or equal to the short-circuit threshold value, or directly pre-charge the storage capacitor (118) if the voltage initially measured across the terminals of the storage capacitor (118) is greater than the short-circuit threshold value.

6. Short circuit detection device (100) according to one of claims 3 to 5, wherein, when the anode of the second thyristor (114) is coupled to the negative terminal of the battery, the control circuit (124) is configured to control the first switch (108) such that it is conducting during the short circuit detection phase and during the precharging of the storage capacity (118).

7. A short-circuit detection device (100) according to one of claims 3 to 6, wherein the control circuit (124) is configured such that, after precharging the storage capacitor (118), the first and second switches (108, 110) are turned on and the first and second thyristors (112, 114) are turned off.

8. A short-circuit detection device (100) according to one of claims 3 to 7, wherein the third switch (120) is a third thyristor, and wherein the control circuit (124) is configured to apply a control signal to the trigger of the third thyristor.

9. Short-circuit detection device (100) according to one of claims 3 to 8, wherein, during a phase of disconnection of the battery from the bus implemented after precharging of the storage capacity (118), the control circuit (124) is configured to turn on the third switch (120) after having opened the first and second switches (108, 110).

10. Short-circuit detection device (100) according to one of claims 3 to 9, wherein, when determining the voltage across the storage capacitor (118) implemented during the short-circuit detection phase, the control circuit (124) is configured to block the second thyristor (114).

11. Vehicle battery monitoring system (1000), comprising at least one short circuit detection device (100) according to one of claims 3 to 10.

12. Electrical power converter (2000) comprising at least one short-circuit detection device (100) according to one of claims 1 or 2.

13. An electrical power converter (2000) according to claim 12, wherein the first and second thyristors (112, 114) are part of the switching cells of the electrical power converter (2000).

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