Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
  • H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
  • H02H9/025—Current limitation using field effect transistors
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
  • H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
  • H02H9/041—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage using a short-circuiting device

Definitions

• the present invention relates to the field of protection circuits for electrical equipment, and in particular DC power supply and / or distribution systems.
• an overcurrent can be caused by a short-circuit, a surge or a lightning
• - Overcurrent can also occur during the start-up phase or when connecting electrical equipment to the network.
• protection devices are known to reduce the effects of these current overloads, and in particular the risks of deterioration of electrical equipment.
• Such protection devices may be used, for example, upstream of a storage capacitor connected in parallel with an electrical equipment item to be protected.
• a first solution to reduce the risk of deterioration of electrical equipment is to electrically connect a series of limiting resistance of the equipment to be protected. This limiting resistor is useful for limiting the strong current draw at the start of the equipment to be protected, and more precisely during the pre-charging of the storage capacitor.
• the operating principle of such an assembly is as follows.
• the electrical switch 13 is connected to the limiting branch 1 1 so that the electric current from the power source 14 flows through the limiting branch 1 January.
• the passage of the current through the resistor 17 makes it possible to limit the strong current draw at the start of the equipment to be protected 15.
• the storage capacitor 16 is charged.
• the electrical switch 13 switches the flow of the current of the limiting branch 1 1 to the conduction branch 12. This limits the losses energy related to the use of limiting resistance 17.
• a disadvantage of the assembly illustrated in FIG. 1 is that it does not make it possible to keep the electronic equipment 15 under tension when the electric switch 13 is switched.
• another disadvantage of the protective devices The above mentioned utilities using a limiting resistor 17 are that they do not allow charging of the constant current storage capacitor 16, the limiting resistor 17 combined with the storage capacitor 16 constituting an RC circuit. This induces an accelerated aging of the storage capacitor. Moreover, this does not make it possible to predict the value of a fault current in the event of abnormal operation, which can vary according to the equivalent resistance of the circuit (taking into account the possible resistances of the components upstream and downstream of the circuit). protection device), this uncertainty on the fault current may induce one of the risks on the protection of the electronic equipment downstream of the protection device.
• An object of the present invention is to provide a protection device of an electrical equipment to overcome at least one of the aforementioned drawbacks.
• the invention proposes a protection device for electrical equipment including:
• the protective device comprises:
• a first current limiting branch including a current source for producing (i.e. maintaining) a constant electric current for a given voltage range
• a control unit for switching the operating mode of the device between:
• the impedance of the conduction branch being less than or equal to 10% of the impedance of the limiting branch in the second mode of operation.
• control unit can be electrically connected to the conduction branch to control the activation and deactivation of said conduction branch so as to switch the device between the first and second modes of operation, the limitation branch being not controlled by the steering unit;
• the current source may comprise a transistor, such as a JFET transistor or a MOSFET transistor:
• the current source may comprise a two-terminal current limiting semiconductor element such as a current limiting diode, for example made of silicon, or of silicon carbide, or of any other semiconductor material; the current limiting branch may furthermore comprise an electrical resistance mounted in series with the current source;
• the conduction branch may comprise a switch controlled as a transistor, such as a JFET transistor, a MOSFET transistor (or a bipolar transistor):
• the drain (or the collector) of the transistor being connected to the input terminal, where the source (or emitter) of the transistor is connected to the output terminal,
• the gate (or the base) of the transistor being connected to the control unit; - the steering unit may include:
• control unit may comprise a self-polarization circuit for delaying the activation of the conduction branch
• control unit comprises a control circuit for generating a signal for blocking the conduction branch when the voltage and / or the intensity at the output of the protection device is greater than a threshold value;
• the limiting and conduction branches can be integrated into a monolithic component such as a JFET transistor or a MOSFET transistor.
• FIG. 1 is a schematic representation of a device of the prior art for protecting a load
• FIG. 2 is a block diagram of a load protection device according to the present invention
• FIG. 3 is a block diagram of a first variant embodiment of the load protection device of the present invention
• FIG. 4 is a block diagram of a second variant embodiment of the load protection device of the present invention.
• FIG. 5 is a block diagram of a third variant embodiment of the load protection device of the present invention.
• FIG. 6 is a graph illustrating current curves as a function of the voltage across a current limiting branch, including:
• FIG. 7 is a graph illustrating current curves as a function of the voltage at the terminals of the protection device in FIG.
• the device for protecting an electric charge comprises an input terminal 31 intended to be electrically connected in series with an electric power supply source, and an output terminal 32 intended to be connected. electrically to an electrical charge to be protected 23. Between the input 31 and output 32 terminals, the device comprises two branches each having a respective function:
• the device also comprises a control unit 24 to allow the passage of the current:
• the limiting branch 21 is always electrically conductive, so that the load 23 to be protected is always powered, even during the transition between the first and second modes of operation.
• the conduction branch 22 is electrically conductive only in the second mode of operation.
• the first mode of operation is advantageously activated when an anomaly - such as a current or voltage overload - is detected.
• control unit 24 only controls the activation and deactivation of the conduction branch 22, the limitation branch 21 not being controlled by the control unit 24. This simplifies the mounting of the load protection device.
• the device illustrated in FIG. 2 effectively protects the load 23 of an electric circuit by limiting the current flowing through it when a malfunction is detected.
• control unit 24 controls the deactivation of the conduction branch 22 to induce the passage of the electric current (generated upstream of the input terminal) to through the limitation branch 21.
• the protection device illustrated in Figure 2 reduces the risk of degradation of the electrical components located downstream of the output terminal. 2.
• the current limiting branch 21 makes it possible to limit the current flowing in the load 23 to a target intensity value when the second mode of operation of the device is activated. This target value is provided sufficient to ensure the proper functioning of the load 23.
• the limiting branch 21 comprises one (or more) source (s) of current - in particular unidirectional (s) - to allow the passage of the current from the input terminal 31 to the output terminal 32.
• current source one (or more) electrical component (s) arranged (s) to produce a constant electric current for a given voltage range.
• the dynamic variation of the impedance of the current source corresponds - in the case of a current source consisting of a JFET transistor normally passing (called "Normally-on") - to the passage of a linear conduction mode to a mode of conduction in saturation mode. This occurs when the voltage across the current source transistor becomes greater than a saturation voltage Vsat of said transistor. In saturation mode the impedance varies dynamically with the voltage so that the current is kept constant. The operation is then analogous to that of a current source that produces and maintains a constant current regardless of the voltage at its terminals.
• the fact that the limiting branch 21 comprises a current source makes it possible to charge a storage capacitor 26 (connected in parallel with the load 23 to be protected) with a constant current.
• the current source comprises a transistor, such as a JFET transistor or a MOSFET transistor.
• the drain of the transistor is electrically connected to the input terminal 31 of the device, while the gate and the source of the transistor are electrically connected to the output terminal 32 of the device.
• the use of a JFET or MOSFET transistor has the advantage of facilitating the implementation of the device.
• the current source may consist of a silicon carbide current limiting diode.
• the use of a current limiting diode makes it possible to dispense with the presence of a control electronics.
• the fact that the diode is silicon carbide provides a component capable of withstanding high energy levels, of the order of 0.1 J to 50J.
• the limiting branch 21 may comprise one (or more) resistive element (s) heat dissipation (s) mounted (s) in series with the (the) source (s) current. This makes it possible to dissipate a greater electrical power by Joule effect in the event of a current overload between the power supply source 25 and the load 23.
• Conduction branch 22 ensures the flow of electric current in steady state. It preferably has a low impedance to limit voltage drops across the load 23.
• the impedance of the conduction branch 22 may be less than 1 ohm, preferably less than 0.1 ohm, and even more preferably lower at 0.01 ohms.
• the conduction branch 22 may comprise a switch controllable by the control unit 24.
• This switch may be of any type known to those skilled in the art.
• the switch is for example a mechanical switch or a hybrid switch.
• the switch of the conduction branch 22 must be able to move from a closed state to an open state very quickly after the detection of an anomaly (overcurrent and / or overvoltage). This is why the switch of the conduction branch 22 is preferably a static switch. This has the advantage of switching very quickly between a closed state and an open state (switching time less than or equal to one hundred microseconds). Another advantage of using a static switch is that it can withstand high voltages and currents.
• the switch of the conduction branch consists of a transistor, such as a JFET transistor or a MOSFET transistor (or a bipolar transistor):
• the drain (or collector) of the transistor being connected to the input terminal, the source (or emitter) of the transistor being connected to the output terminal, - the gate (or the base) of the transistor being connected to the 'Control unit.
• the control unit 24 makes it possible to control the activation and deactivation of the conduction branch 22.
• control unit 24 makes it possible to open or close the conduction branch 22 so that the current flowing in the protection device passes through:
• the impedance of the conduction branch 22 is chosen to be less than or equal to 10% of the impedance of the limiting branch 21 in the second mode of operation.
• the passage of the current through the conduction branch 22 is thus favored in the second mode of operation. This makes it possible to limit the losses by Joule effect when the second mode of operation of the protection device is activated.
• the control unit 24 comprises a detection circuit 242 for a voltage variation at the output of the load protection device.
• the control unit may comprise a circuit for detecting a variation in current at the output of the protection device. This (or these) circuit (s) of detection makes it possible to identify an anomaly (overvoltage and / or overcurrent) likely to damage the load 23.
• a control circuit 243 of the control unit 24 transmits a blocking signal on the gate of the controllable switch of the conduction branch 22.
• This blocking signal induces the opening of the controllable switch so as to deactivate the conduction branch 22.
• the current then flows exclusively through the current limiting branch 21.
• the control circuit 243 When the voltage variation detected by the detection circuit 242 becomes lower than the threshold voltage, the control circuit 243 no longer emits a blocking signal. The controllable switch returns to a conducting state so as to activate the conduction branch 22. The current then flows both through the limiting branch 21 and the conduction branch 22.
• control unit 24 may comprise a self-biasing circuit 241 between the detection circuit 242 and the gate of the controllable switch.
• the self-biasing circuit 241 delays the reactivation of the controllable switch. More precisely, the self-biasing circuit 241 makes it possible to delay the closing of the controllable switch by a non-zero delay corresponding to the discharge time of a capacitor C1 of the self-biasing circuit 241. This makes it possible to limit the risks of degradation of the load, in particular in the case of impulse-type current overloads.
• the storage capacitor 26 causes a strong current draw. This induces the appearance of a current overload in the electrical circuit.
• Detection circuit 242 detects a voltage change at the output terminals of the charge protection device. When this voltage variation becomes greater than the threshold voltage defined by the Zener diode D4, the control circuit 243 transmits a blocking signal to the gate of the controllable switch of the conduction branch 22.
• the blocking signal passes through the self-biasing circuit 241.
• the capacitor C1 of the self-biasing circuit 241 loads. Simultaneously with the charging of the capacitor C1, the application of the blocking signal to the gate induces the opening of the controllable switch: the conduction branch 22 is deactivated.
• the charge protection device then operates according to its first mode of operation: the entire current from the electric power supply source 25 is transmitted to the load 23 via the limiting branch 21 so that the current received by the load 23 is limited to the target intensity value to protect the load 23.
• the storage capacitor 26 is charged, a steady state of the electrical circuit is established.
• the voltage variation at the output of the protection device decreases, the detection circuit 242 detecting this decrease.
• the blocking signal is interrupted.
• the capacitor C1 of the self-biasing circuit 241 discharges towards the gate of the controllable switch so as to keep the latter in a locked state for a few moments. This makes it possible to delay the closing of the controllable switch.
• the gate of the controllable switch is no longer powered.
• the controllable switch then goes from a blocked state (ie open) to a on state (ie closed).
• the conduction branch 22 is reactivated.
• the charge protection device then operates according to its second mode of operation: the current coming from the electric power supply source 25 is transmitted to the load 23 via the limiting branch 21 on the one hand and the conduction branch 22 on the other hand.
• the detection circuit 242 detects an output voltage variation greater than the threshold voltage defined by the Zener diode D4.
• the control circuit 243 transmits to the gate of the controllable switch a blocking signal through the self-biasing circuit 241. This blocking signal opens the controllable switch to deactivate the conduction branch 22.
• the first mode of operation is implemented.
• the control unit 24 controls the reactivation of the conduction branch 22 as described above. 5.
• the limiting 21 and conduction branches 22 may be integrated in a monolithic unitary component made of silicon or silicon carbide (or another semiconductor material, preferably with a wide bandgap) such that a JFET transistor or a MOSFET transistor or a bipolar transistor. This limits the space occupied by the second branch, and therefore the size of the protective device.
• FIGS. 4 and 5 two exemplary embodiments of a monolithic component incorporating the limiting 21 and conduction branches 22 on the same substrate are illustrated.
• the monolithic component has a JFET type structure. It comprises a substrate 61 common to the limiting 21 and conduction branches 22.
• the rear face of the N-type doped substrate 61 comprises a lower N-doped lower layer 62 covered with a metal layer 63 forming the drain.
• the front face of the substrate 61 comprises P-doped buried regions 64 on which is disposed an N-type top layer 70 forming a lateral channel of the limiting and conduction branches 22.
• On this upper layer 70 are arranged upper regions 68 of type P. These regions partially overlap the upper layer 70
• first and second metal electrodes 65a, 65b are disposed above the upper regions 68 and the upper layer 70. These first and second electrodes 65a, 65b form a control gate of the branch 22 and define the characteristics of the limiting branch 21.
• the monolithic component comprises a first separation trench for defining the limiting 21 and conduction branches 22. This first trench extends through the upper layer 70 of the component to the buried regions 64 to allow their connection.
• the first separation trench extends to a depth at least equal to that of the upper layer 70.
• a layer of electrically insulating material 66 covers the first metal electrode 65a forming a grid of the branch 21, while no layer of electrically insulating material covers the second electrode 65b forming a gate.
• a source metal layer 67 covers the entire surface of the monolithic component. So :
• the first electrode 65a forming a gate is electrically isolated from the source metal layer 67: this first stack of layers of the monolithic component constitutes the conduction branch whose gate (first electrode) is intended to be electrically connected to the transmission unit; control 24, while the drain 63 and the source 67 are intended to be respectively connected to the input terminal 31 and the output terminal 32 of the load protection device;
• this second stack of layers of the monolithic component constitutes the current limiting branch 21 whose gate 65b and the source 67 are intended to be connected to the output terminal 32 of the load protection device, while the drain 63 is intended to be connected to the input terminal 31 of the device.
• the peculiarity of the monolithic structure component JFET illustrated in FIG. 4 is that the conduction branch 22 is activated unless an electric voltage is applied to the gate electrode (known under the standard name "NORMALLY ON"). the limitation branch is permanently activated.
• the monolithic component illustrated in FIG. 5 differs from the component illustrated in FIG. 4 in that its structure is of the MOSFET type.
• the peculiarity of the monolithic structure component MOSFET illustrated in FIG. 5 is that the conduction branch 22 is deactivated unless an electric voltage is applied to the gate electrode, the limiting branch being permanently activated.
• It comprises a substrate 73 common to the limiting 21 and conduction branches 22.
• the rear face of the N-type doped substrate 73 comprises a lower N-doped lower layer 72 covered with a metal layer 71 forming a drain.
• the substrate 73 comprises first P-doped buried regions 74 at its upper face.
• the front face of the substrate 73 is covered by an upper layer 82 of N.
• the upper layer 82 of the conduction branch 22 comprises:
• the monolithic component comprises a first MOSFET trench extending through the upper layer 82 to the substrate 73. It also includes a fourth P-type buried region 83 in the bottom of the trench, the fourth buried region 83 and the first buried regions 74 defining N-type channels in the substrate 73.
• the monolithic component comprises a second separation trench for defining the limiting branches 21 and conduction 22. This second trench extends through a second central zone 76 of the component to the first buried regions 74 to allow their connection.
• the second separation trench extends to a depth at least equal to that of the upper layer 82.
• First and second thin oxide layers 78a and 78b defining the gate oxide of the MOSFETs partially cover the upper face of the first buried regions 74, the second zones 76, the fourth buried regions 83 and the upper layer 82.
• the component comprises a first metal electrode 79 forming the control gate of the branch 22 on the first layer 78a.
• a layer of electrically insulating material 80 covers the first metal electrode 79 forming a grid of the branch 21. While no layer of electrically insulating material covers the second layer 78b forming the gate of the MOSFET limitation branch.
• Metal layers 77 contact the first buried regions 74 and the second zones 76 of the limiting and conduction branches 21, 22.
• a source metal layer 81 covers the entire surface of the monolithic component. So :
• this first stack of layers of the monolithic component constitutes the conduction branch whose gate (first electrode) is intended to be electrically connected to the control 24, while the drain 71 and the source 81 are intended to be respectively connected to the input terminal 31 and the output terminal 32 of the load protection device;
• this second stack of layers of the monolithic component constitutes the current limiting branch 21 whose source 81 are intended to be connected to the terminal output 32 of the load protection device, while the drain 71 is intended to be connected to the input terminal 31 of the device.
• the circuit described above is suitable for use in a DC or AC power grid. It protects electrical equipment from overloads of current likely to appear in the electrical network in the event of a start-up phase of the equipment to be protected, pre-charging of a storage capacitor or lightning shock. It can be used as a current regulator function, delivering a constant current to any AC or DC load, or to detect and limit any inrush current on the AC or DC network in case of overvoltage.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Emergency Protection Circuit Devices (AREA)
• Protection Of Static Devices (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=58739074

Family Applications (1)

Country Status (8)

Families Citing this family (2)

Family Cites Families (15)

• 2017
  • 2017-01-11 FR FR1750242A patent/FR3061812B1/fr not_active Expired - Fee Related
• 2018
  • 2018-01-11 KR KR1020197021898A patent/KR20190101418A/ko unknown
  • 2018-01-11 US US16/476,205 patent/US20200373754A1/en not_active Abandoned
  • 2018-01-11 JP JP2019557683A patent/JP2020505901A/ja active Pending
  • 2018-01-11 WO PCT/EP2018/050607 patent/WO2018130594A1/fr unknown
  • 2018-01-11 CN CN201880006215.0A patent/CN110235327A/zh active Pending
  • 2018-01-11 CA CA3087843A patent/CA3087843A1/fr active Pending
  • 2018-01-11 EP EP18700216.7A patent/EP3568894A1/fr not_active Withdrawn

Also Published As

Similar Documents

Legal Events