Classifications

• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03K—PULSE TECHNIQUE
  • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
  • H03K17/08—Modifications for protecting switching circuit against overcurrent or overvoltage
  • H03K17/082—Modifications for protecting switching circuit against overcurrent or overvoltage by feedback from the output to the control circuit
  • H03K17/0828—Modifications for protecting switching circuit against overcurrent or overvoltage by feedback from the output to the control circuit in composite switches
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03K—PULSE TECHNIQUE
  • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
  • H03K17/16—Modifications for eliminating interference voltages or currents
  • H03K17/161—Modifications for eliminating interference voltages or currents in field-effect transistor switches
  • H03K17/165—Modifications for eliminating interference voltages or currents in field-effect transistor switches by feedback from the output circuit to the control circuit
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03K—PULSE TECHNIQUE
  • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
  • H03K17/16—Modifications for eliminating interference voltages or currents
  • H03K17/168—Modifications for eliminating interference voltages or currents in composite switches

Definitions

• the present invention relates to a switch system with a voltage limiting circuit, a switching arm and an electrical converter.
• a switch comprising:
• the current input terminal and the current output terminal being intended to have a switch voltage between them, and the control terminal and the current output terminal being intended to present between them a control voltage controlling the switch voltage
• a discharge branch of the control terminal of the switch the discharge branch being connected to the control terminal of the switch and comprising a discharge resistor, and the discharge branch being intended to be traversed by at least one a part of a discharge current of the control terminal so that the control voltage decreases,
• the voltage limiting circuit generally comprises a transient-voltage-suppressor (TVS) component, such as a Zener diode arranged to switch to the reverse mode (avalanche mode) when the switch voltage becomes too high to provide the injected current.
• TVS transient-voltage-suppressor
• TVS components have the problem of deriving a lot of temperature and their dynamic resistance is not properly defined for currents from 100 to 300 mA, generally used in voltage converters for the automotive field.
• the choice of TVS is very small and the power induced in these TVS is strong.
• the invention aims to overcome at least in part the aforementioned problems.
• the voltage limiting circuit comprises:
• an operational amplifier arranged to compare a voltage representative of the switch voltage with a reference voltage, in order to provide an output voltage according to the comparison
• a current generating circuit designed to generate the injected current as a function of the output voltage of the operational amplifier.
• the current generating circuit comprises: - a first current generating sub-circuit designed to generate an intermediate current as a function of the output voltage of the operational amplifier; and a second current generating sub-circuit designed to generate the injected current as a function of the intermediate current.
• the first sub-circuit comprises a first transistor having a current arrival terminal, the arrival terminal current of the first transistor and a power supply terminal of the operational amplifier are connected to a common terminal, and the first transistor is controlled by the output voltage of the operational amplifier so as to generate the intermediate current through the common terminal.
• the second sub-circuit comprises a second transistor which has a current input terminal (e2), a current output terminal (c2) and a control terminal (b2) and which is intended to provide the injected current (ij through its current output terminal (c2).
• the second subcircuit comprises:
• first and second resistors connected to each other at a mid-point to which the control terminal of the second transistor is connected
• a third resistor connected between the current input terminal of the second transistor and the first resistor.
• the current generating circuit further comprises a resistor connected between the discharge branch and an output terminal of the operational amplifier.
• the current generating circuit further comprises a diode connected between the discharge branch and the output terminal of the operational amplifier for preventing current from entering the operational amplifier through its output terminal.
• the voltage limiting circuit further includes a voltage divider circuit adapted to divide the switch voltage to provide the voltage representative of the switch voltage.
• the switch system further comprises a charging branch of the control terminal, different from the discharge branch, wherein the charging branch is connected to the control terminal of the switch, wherein the charging branch comprises a load resistor and a load-carrying diode towards the control terminal of the switch, wherein the charging branch is intended to be a current for passing through the load resistor and the load diode, forming at least a portion of a load current of the control terminal so that the control voltage increases, and wherein the discharge branch includes in addition to a blocking discharge diode towards the control terminal of the switch, the at least a portion of the discharge current being for passing through the discharge resistor and the discharge diode.
• the switch system further comprises a power supply of the voltage limiting circuit, the power supply having a DC voltage source, a resistor connected between the DC voltage source and an input terminal of the voltage limiting circuit. voltage limiting circuit and capacitance connected between the input terminal of the voltage limiting circuit and the current output terminal of the switch.
• the switch system further comprises a diode connected between the resistor and the input terminal of the voltage limiting circuit in the direction of the input terminal of the voltage limiting circuit.
• the voltage limiting circuit further comprises a device designed to fix, in the absence of a switch voltage, the voltage representative of the switch voltage at a default voltage lower than the reference voltage. .
• a switching arm comprising two switch systems respectively comprising two switches connected to each other at a mid-point, and in which at least one of the switch systems, preferably both, is in conformity with one another.
• DESCR1PT10N OF F1GURES Figure 1 is an electrical diagram of an electrical converter implementing the invention.
• FIG. 2 is a circuit diagram of a switch control circuit of the electrical converter of FIG. 1, according to a first embodiment of the invention.
• FIG. 3 is a circuit diagram of a switch control circuit of the electric converter of FIG. 1, according to a second embodiment of the invention.
• Figure 4 is a circuit diagram of a switch control circuit according to the state of the art.
• a zero electrical quantity is for example a negligible electrical magnitude in front of other electrical quantities of the same nature.
• a very large electrical quantity is, for example, an electrical quantity at least 100 times, preferably at least 1000 times, larger than the other electrical quantities of the same kind.
• the electric converter 100 is for example used in a motor vehicle.
• the electrical converter 100 is for example an inverter or a rectifier, or even a DC / DC converter.
• the electric converter 100 has a plurality of switching arms.
• the electrical converter 100 comprises two switching arms, designated respectively by the references 102 1 and 102 2 .
• the index "1" will be used for the elements relating to the first switching arm 102i, while the index "2" will be used for the elements relating to the second switching arm 102 2 .
• Each switching arm 102 1 , 102 2 has a high side switch 104 1 , 104 2 and a low side switch 104 1 ', 104 2 '.
• Each switch 104i, 104i ', 104 2 , 104 2 ' has a current input terminal Ci, Ci ', C 2 , C 2 ', a current output terminal Ei, Ei ', E 2 , E 2 ' and a control terminal Gi, Gi ', G 2 , G 2 '.
• the switches 104i, 104i ', 104 2 , 104 2 ' are insulated gate bipolar transistors or 1GBT (of the English “lnsulated gate Bipolar Transistor”) having a collector, an emitter and a grid forming respectively the current input terminal, the current output terminal and the control terminal.
• 1GBT of the English “lnsulated gate Bipolar Transistor”
• the switches 104i, 104i ', 104 2 , 104 2 ' could be insulated gate field effect transistors or MOSFETs (of the "Metal Oxide Semiconductor Field Effect Transistor") having a drain, a source and a gate, respectively forming the current input terminal, the current output terminal and the control terminal.
• MOSFETs of the "Metal Oxide Semiconductor Field Effect Transistor”
• the collector Ci, Ci ', C 2 , C 2 ' and the emitter Ei, Ei ', E 2 , E 2 ' have a collector voltage between them.
• switch current a collector-emitter current IEC , CE , CE2 , CE2 '(hereinafter referred to as the switch current) flows between them.
• the gate Gi, Gi ', G 2 , G 2 ' and the emitter E 1 , E 1 ', E 2 , E 2 ' have between them a gate-emitter voltage V GEI , V GE T, V GE2 , V GE 2 ' (hereinafter referred to as control voltage) defining the open or closed state of the switch 104i, 104i ', 104 2 , 104 2 ' so as to control the switch voltage VCEI, VCET, VCE2, VCE2 ' .
• the switch 104i, 104T, 104 2 , 104 2 ' is designed to assume the open state when the control voltage V IEC , V IEC ', V GE2 , V GE2 'is at an opening value of the switch 104i, 104T, 104 2 , 104 2 '.
• the opening value is a low value, for example zero.
• current Î switch CIS, CIS Î 'Î CE2, CE2 Î' is zero and the voltage VCEI switch VCEI ', Vce2, Vce2 is non-zero.
• the switch 104i, 104i ', 104 2 , 104 2 ' is designed to take the closed state when the control voltage VGEI, VGEI ', VGE2, VGE2' is at a closing value of the switch 104i , 104i ', 104 2 , 104 2 '.
• the closing value is a high value, for example 10V or more.
• the switch current ICEI, ICEI ', ÎCE2, ÎCE2' is non-zero and the switch voltage VGEI, VCEI ', VCE2, VCE2' is zero.
• the emitter E 1 , E 2 of the high-side switch 104 1 , 104 2 and the collector C 1 ', C 2 ' of the low-side switch 104 1 ', 104 2 ' are connected to one another at a midpoint PI, P2 intended to be connected to a coil (symbolized by dotted lines) of an electric machine such as an electric motor.
• the switching arms 102 1 , 102 2 are connected to a first DC voltage source 108, such as a charged battery or capacitor, providing a VBAT voltage. More precisely, for each switching arm 102i, 102 2 , the collector Ci, C 2 of the high-side switch 104i, 104 2 is connected to a positive terminal of the voltage source 108, while the emitter Ei ' , E 2 'of the low side switch 104i', 104 2 'is connected to a negative terminal of the voltage source 108 (the negative terminal being generally connected to a chassis of the vehicle).
• a first DC voltage source 108 such as a charged battery or capacitor
• the electrical converter 100 further comprises, for each switch 104i, 104i ', 104 2 , 104 2 ', a respective control circuit 112i, 112i ', 112 2 , 112 2 ' of this switch 104i, 104i ', 104 2 , 104 2 ', both forming together a switch system.
• the electrical converter 100 further comprises a second DC voltage source 114 designed to provide a DC voltage VIN between a positive terminal and a negative terminal, in order to electrically power the control circuits 112i, 112i ', 112 2 , 112 2 '. .
• the negative terminal of the voltage source 114 will subsequently be taken as the electrical ground, so that, unless otherwise indicated, when a voltage is mentioned, it will be considered with respect to the negative terminal of the voltage source 114.
• the DC voltage VIN is usually lower than the voltage VBAT.
• the control circuit 112i first comprises a supply stage 115 connected to the voltage source 114 to supply a supply voltage V (taken with respect to the emitter Ei of the switch 104i) from the DC voltage V IN .
• the power stage 115 includes a resistor R connected between the DC voltage source 114 and an output terminal S of the power stage 115 and a capacitor C connected between the output terminal S and the emitter Ei of the switch 104i.
• the supply voltage V is the voltage across the capacitor C.
• the supply stage 115 further comprises a diode D connected between the resistor R and the output terminal S of the supply stage 115, and arranged in a conductive manner towards the output terminal S.
• This diode D is present only in the supply stages 115 of the high-side control circuits 112 1 , 112 2 .
• the supply stages 115 of the low-side control circuits 112i ', 112 2 ' include only the resistor R and the capacitor C.
• the control circuit 112i further comprises a driver 116 designed to provide, on an output terminal of the driver 116, a driving voltage V PI with respect to the transmitter Ei, this driving voltage V PI selectively taking the value of opening and the closing value of the switch 104i.
• the driver 116 is connected to the terminals of the voltage source 114 for its power supply, for example via the supply stage 115.
• the control circuit 112i further comprises an interface 118 connected on one side to the driver 116 for receiving the driving voltage V PI and, on the other hand, to the gate Gi of the switch 104i (the transmitter Ei of the switch 104i is also connected to the driver 116).
• the interface 118 is intended to define the speed at which the control voltage V GEI reaches the driving voltage V PI , and therefore the switching speed of the switch 104i.
• the interface 118 comprises two branches each connected between the output terminal of the driver 116 and the gate Gi of the switch 104i.
• the first part, said discharge comprises a R D resistor and a diode D D pass toward the output terminal of the driver 116.
• the second branch, said load comprises a resistor Rc and a diode pass towards the gate Gi of the switch 104i.
• the gate Gi When the driving voltage V PI is at the opening value (0 V), the gate Gi is intended to discharge with respect to the transmitter Ei. A discharge current Î D then leaves the gate Gi so that the control voltage V GEI reaches the opening value. At least a portion of this discharge current D passes through the discharge branch of the interface 118i, so that the discharge rate is at least partly defined by the resistance R D. In the example described where the gate Gi is connected only to the interface 118i, it is the entire discharge current D which passes through the discharge branch. Nevertheless, in other embodiments where the gate Gi is further connected to one or more auxiliary devices, for example a protection device, only a part of the discharge current I D would pass through the discharge branch, the remainder passing through. in the auxiliary device or devices.
• auxiliary devices for example a protection device
• the gate Gi When the driving voltage V PI is at the closing value, the gate Gi is intended to charge so that the control voltage V GEI reaches the closing value. It then receives a charge current (in the opposite direction to the discharge current D shown in FIG. 2), at least a portion of which comes from the charging branch of the interface 118. Thus, the charging speed is at least part defined by the resistance Rc. In the example described where the gate Gi is connected only to the interface 118i, all the charging current comes from the load branch.
• the parasitic inductance Li is intended to be traversed by the switch current IEC .
• the current ICEI switch decreases and causes the appearance of a negative VLI inductance voltage, which causes the occurrence of an overvoltage of the VCEI switch voltage.
• this overvoltage can deteriorate the switch 104i.
• control circuit 112i furthermore comprises a voltage limiting circuit 120 designed to inject a current L into the discharge branch, between the discharge resistor R D and the control terminal Gi of the switch. 104i, in order to limit the switch voltage VCEI-
• the voltage limiting circuit 120 firstly comprises a voltage divider circuit 122 designed to multiply the switch voltage V IEC by a factor F less than one, to provide a voltage V * IEC .
• the voltage V * IEC is thus representative of the switch voltage V IEC .
• the voltage divider circuit 122 comprises first and second resistors R1, R2 connected to each other at a midpoint.
• the first resistor RI is further connected to the collector Ci and the second resistor is further connected to the emitter Ei.
• the voltage of the midpoint forms the voltage V * IEC .
• the voltage limiting circuit 120 further comprises a component TL43xx forming an operational amplifier AO, a reference voltage generator VREF and a first current generating sub-circuit 124.
• the TL43xx component is preferably a TL431 component 123.
• the TL431 component 123 has a cathode K and anode A connected to the emitter Ei of the switch 104i.
• the operational amplifier AO is arranged to compare the voltage V * IEC to the reference voltage VREF, in order to provide an output voltage Vs as a function of the comparison.
• a positive terminal "+” of the operational amplifier AO is connected between the resistors R1 and R2.
• a negative terminal "-" of the operational amplifier AO is connected to the reference voltage generator VREF, the latter being thus connected between the negative terminal "-” of the operational amplifier AO and the anode A.
• output voltage Vs is negative when the voltage V * IEC is lower than the reference voltage VREF, zero when the voltage V * IEC is equal to the reference voltage VREF and positive when the voltage V * IEC is greater than the reference voltage VREF. More precisely, the output voltage Vs is higher as the voltage V * IEC is greater than the reference voltage VREF, up to a ceiling (saturation of the operational amplifier AO).
• the subcircuit 124 is designed to generate an intermediate current I KA from the output voltage Vs of the operational amplifier AO, when the voltage V * IEC is greater than the reference voltage VREF. More precisely, the intermediate current I KA is zero when the output voltage Vs is negative or zero and positive when the output voltage Vs is positive. In addition, the intermediate current I KA is all the greater than the output voltage Vs is large.
• the sub-circuit 124 comprises a first transistor TRI having a current input terminal C1, a current output terminal el and a control terminal b1.
• the transistor TRI is a bipolar transistor.
• the current input terminal C1 and a power supply terminal of the operational amplifier AO are connected to the cathode K of the TL431 component.
• the sub-circuit 124 further comprises a diode D D connected between the cathode K and the anode A. It is passing in the direction of the cathode K.
• the transistor TRI is controlled by the output voltage Vs of the operational amplifier AO, so as to generate the intermediate current K KA through the cathode K.
• the voltage limiting circuit 120 further includes a second current generating sub-circuit 126 adapted to generate the injected current L from the intermediate current I KA -
• the sub-circuit 126 comprises a second transistor TR2 in current generator assembly.
• the transistor TR2 has a current input terminal e2, a current output terminal c2 connected to the discharge branch of the interface 118 and a control terminal b2.
• transistor TR2 is a bipolar transistor.
• the sub-circuit 126 includes first and second resistors R3, R4 connected to each other at a midpoint at which the control terminal b2 of the transistor TR2 is connected.
• the resistor R3 is further connected to an input terminal E of the voltage limiting circuit 120 and the resistor R4 is connected to the cathode K of the TL431 component.
• Sub-circuit 126 further comprises a third resistor R5 connected between the current input terminal e2 of transistor TR2 and input terminal E.
• the resistors R3, R5 are connected to each other.
• Transistor TR2 is thus intended to supply current I L through its current output terminal c2.
• the injected current Î L is even larger than the intermediate current Î KA is large.
• the two sub-circuits 124, 126 thus form a current generating circuit designed to generate the injected current L from the output voltage Vs of the operational amplifier A0.
• the input terminal E is connected to the output terminal S of the power stage 115 so as to allow the power supply of the voltage limiting circuit 120.
• the voltage limiting circuit 120 further comprises a device designed to apply to the positive terminal of the operational amplifier AO, in the absence of voltage V IEC , a default voltage slightly lower than the reference voltage V REF (for example, at least 90% of the voltage V REF ).
• the operational amplifier AO is by default close to its switching point (voltage of its positive terminal equal to the voltage V REF ) which allows it to switch faster.
• this device comprises a resistor R6 connected between the input point E of the voltage limiting circuit 120 and the positive terminal of the operational amplifier AO.
• the voltage V * IEC is given by the equation:
• this device sets the voltage V * IEC (received by the positive terminal of the operational amplifier AO) to:
• the switch 104i is in the closed state.
• the driving voltage V PI and the control voltage V GEI are at the closing value of the switch 104i (10 V).
• the switch voltage V IEC is zero and the switch current IEC is constant (non-zero) and moves towards the midpoint Pi.
• the inductance voltage V LI is zero.
• the driving voltage V PI goes to the opening value (0 V) and a non-zero discharge current D D flows from the gate Gi to the pilot 116, through the resistor discharge R D.
• the switch voltage V IEC begins to increase, then the switch current IEC drops off. At this moment, the inductance voltage V LI becomes more and more negative, causing an overvoltage of the collector-emitter voltage V IEC .
• the voltage across the resistor R2 then reaches the reference voltage V REF of the component TL431 123, so that the latter draws a current I KA which will activate the transistor TR2 in current generator assembly so as to create the current I L.
• the current I L is added to the discharge current to form a current I passing through the RD discharge resistor R D.
• the control voltage V GEI is found at the terminals of the discharge resistor R D , the current I RD is fixed by this control voltage V GEI .
• the appearance of the current Î L diminishes the Î D discharge current until the diode D becomes blocked causing a current Î D zero discharge.
• Voltage V GEI becomes constant, as is switch current IEC .
• the switch 104i is then in linear mode. The surge is thus limited.
• the driver 116 places the pilot voltage VPi at the closing value of the switch 104i. It is the capacitor C which supplies the energy to the driver 116 to charge the gate Gi of the switch 104i.
• the diode D prevents the capacitor C from being discharged.
• the resistor R at least partially prevents the appearance of a current peak at the output of the DC voltage source 114 (and therefore in the diode D of the high side) resulting from the sudden application of a voltage to the capacity C.
• the voltage limiting circuit 120 has the advantage of having a low temperature drift, in any case lower than that of a TVS.
• the power dissipated by the voltage limiting circuit consumes 120 corresponds mainly to the power dissipated in the resistor R1, which is equal to the square of the voltage across the resistor RI divided by the RI resistance.
• this power can be minimized, up to for example a few watts.
• control circuit 112i according to a second embodiment of the invention will now be described in more detail, knowing that the other control circuits 112i ', 112 2 , 112 2 ' are identical.
• the voltage limiting circuit 120 comprises, in addition to the operational amplifier AO and the reference voltage generator V REF , a resistor R L and a diode D L in series connected between the output terminal of the operational amplifier AO and the discharge branch of the interface 118.
• the diode D L prevents the input of current into the operational amplifier AO via its output terminal, when the voltage V * IEC is lower than the reference voltage V REF .
• a voltage limiting circuit 120 according to the state of the art discussed in the introduction is illustrated. 11 comprises in particular a TVS in the form of a Zener diode 402. 11 will be appreciated that during the surge arresting, the power dissipated by the TVS is equal to the product of the injected current i L by the voltage across the TVS . However, when it is desired to limit the voltage to a high voltage (for example 450 volts), this dissipated power can reach several hundred watts.
• the power dissipated in the TVS is 500 mA x 450 V or 225 W.
• the power dissipated in the TVS is therefore much higher than the power dissipated in the voltage limiting circuit 120 of Figures 2 and 3 (which is worth a few watts as explained more above).

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• Electronic Switches (AREA)
• Control Of Electrical Variables (AREA)
• Direct Current Feeding And Distribution (AREA)
• Amplifiers (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=63080128

Family Applications (1)

Country Status (3)

Family Cites Families (3)

• 2018
  • 2018-05-31 FR FR1854719A patent/FR3082067B1/fr active Active
• 2019
  • 2019-05-28 EP EP19726418.7A patent/EP3804137A1/de not_active Withdrawn
  • 2019-05-28 WO PCT/EP2019/063819 patent/WO2019229062A1/fr unknown

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