ELECTRICAL CIRCUIT WITH VOLTAGE CONVERTER AND STARTING CIRCUIT

Abstract

The electrical circuit (100) comprises: - a voltage converter (104) comprising an input terminal (BHV) and at least one switch (Q1); - a driver (106) of the switch (Q1); - a supply capacitor (C3) of the driver (106), connected to the voltage converter (104); and - a starting circuit (108).The starting circuit (108) comprises: - a voltage divider (110) comprising a high part (112) and a low part (114) connected to each other at a midpoint (M), the high part (112) being further connected to the input terminal (BHV) of the voltage converter (104) and comprising, in series, a so-called high resistor (R1) and a capacitor (C); and - a diode (D7) connected between the midpoint (M) and the supply capacitor (C3), conducting towards the supply capacitor (C3) to allow charging of the supply capacitor (C3) at a continuous supply voltage (VOUT) and lower than an output voltage (P16V) of the voltage converter (104). Figure for the abstract: Fig. 1.

Description

Title of the invention: ELECTRICAL CIRCUIT WITH VOLTAGE CONVERTER AND STARTING CIRCUIT Technical field of the invention

[0001] The present invention relates to an electrical circuit with a voltage converter and a starting circuit, as well as to a mobility device comprising such an electrical circuit.

[0002] A mobility device is, for example, a land motor vehicle, a train, an aircraft or a drone. A land motor vehicle is, for example, a motor vehicle, a motorcycle, a motorized bicycle or a motorized wheelchair. Technological background

[0003] An electrical circuit of the type comprising: - a voltage converter comprising an input terminal and at least one switch, the voltage converter being designed to provide an output voltage when an input voltage is present on the input terminal; - a driver designed to drive the voltage converter switch; - a driver supply capacity, connected to the voltage converter in order to be charged by the output voltage; and - a priming circuit.

[0004] In the prior art, the ignition circuit generally comprises a resistor and a switch between the voltage source and the power supply capacitor. An electrical circuit powered by the voltage source turns the switch on at startup, and turns it off thereafter to avoid losses resulting from a current flowing through the resistor. In the event of a switch failure, the latter may short-circuit so that the driver could receive the input voltage directly and be damaged. To avoid this, it is known to provide a protection circuit in the form of a Zener diode and at least one resistor across the power supply capacitor. This Zener diode must be sufficiently sized to maintain a limited voltage in the event of a short-circuit of the switch, which makes it expensive.

[0005] It may thus be desired to provide an electrical circuit of the aforementioned type which makes it possible to overcome at least some of the aforementioned problems and constraints. Summary of the invention

[0006] An electrical circuit of the aforementioned type is therefore proposed, characterized in that the starting circuit comprises: - a voltage divider comprising a high part and a low part connected to each other at a midpoint, the high part being further connected to the input terminal of the voltage converter, the high part comprising, in series, a so-called high resistance and a capacitor; and - a diode connected between the midpoint and the supply capacitor, passing towards the supply capacitor to allow charging of the supply capacitor through the upper part of the voltage divider to a continuous supply voltage lower than the output voltage of the voltage converter.

[0007] Thus, the supply capacitor is charged through the upper part of the voltage divider to a continuous supply voltage lower than the output voltage of the voltage converter when an input voltage is present on the input terminal of the voltage converter.

[0008] Furthermore, thanks to the invention, the starting circuit no longer uses a switch and therefore does not require a Zener diode to protect this switch, the diode connected to the midpoint being responsible for disconnecting the starting circuit from the supply capacitor when the voltage converter supplies the output voltage. Furthermore, the capacitor(s) charge up to the input voltage and then cancel at this moment a current flowing in the high resistance, avoiding losses in the latter.

[0009] The invention may further comprise one or more of the following optional features, in any technically possible combination.

[0010] Optionally, the input voltage is referenced to an electrical ground.

[0011] Also optionally, the capacitance comprises two capacitive components in series.

[0012] Also optionally, the capacitance comprises two capacitive components on two branches in parallel respectively.

[0013] Also optionally, the electrical circuit also comprises an electronic card on which the two capacitive components of the two branches are mounted in parallel.

[0014] Also optionally, each of the two capacitive components in series of each of the two branches in parallel has two terminals, for each branch in parallel, the two terminals of one of the two capacitive components define a line perpendicular to a line defined by the two terminals of the other of the two capacitive components.

[0015] Also optionally, for each of the two branches in parallel, one of the two capacitive components is rotated 90° relative to the other of the two capacitive components.

[0016] Also optionally, the lower part of the voltage divider includes a Zener diode.

[0017] Also optionally, the Zener diode is connected by its cathode to the midpoint.

[0018] Also optionally, the Zener diode is connected by its anode to electrical ground.

[0019] Also optionally, the lower part of the voltage divider includes a resistor.

[0020] Also optionally, the resistance of the lower part of the voltage divider is connected between the midpoint and electrical ground.

[0021] Also optionally, the Zener diode and the resistance of the lower part of the voltage divider are respectively on two branches in parallel.

[0022] Also optionally, the input voltage is DC and the voltage converter is a DC-DC voltage converter.

[0023] Also optionally, the output voltage is lower than the input voltage.

[0024] Also optionally, the voltage converter is a recovery converter.

[0025] Also optionally, the driver includes a microcontroller (402) designed to control the switch.

[0026] Also optionally, the driver comprises an RC circuit connected to the microcontroller to implement self-control of the microcontroller.

[0027] A mobility device comprising an electrical circuit according to the invention is also proposed. Brief description of the figures

[0028] The invention will be better understood with the aid of the following description, given solely by way of example and with reference to the appended drawings in which: - [Fig. 1] is an electrical diagram of an example of an electrical circuit according to the invention, - [Fig.2] is a voltage timing diagram of the electrical circuit of [Fig.l], - [Fig.3] is an electrical diagram of an example of a voltage converter which can be used in the electrical circuit of [Fig.l], and - [Fig.4] is an electrical diagram of an example of a driver that can be used in the electrical circuit of [Fig.l]. Detailed description of the invention

[0029] With reference to [Fig.l], an electrical circuit 100 according to the invention will now be described.

[0030] The electrical circuit 100 firstly comprises a voltage source 102 designed to provide an input voltage HV relative to an electrical ground GND1. The input voltage HV is for example a direct voltage, for example a high voltage greater than 100 V, for example 330 V as in the example illustrated.

[0031] The electrical circuit 100 further comprises a voltage converter 104 designed to provide, from the input voltage HV, an output voltage P16V which is continuous. The voltage converter 104 thus comprises an input terminal BHV connected to the voltage source 102 to present the input voltage HV and an output terminal BPi6v presenting the output voltage P16V with respect to the electrical ground GND1. When the input voltage HV is continuous, the voltage converter 104 is thus a direct-direct converter and the output voltage P16V is preferably lower than the input voltage HV, for example lower than 30 V, for example 16 V as in the example illustrated. To carry out the voltage conversion, the voltage converter 104 comprises at least one switch Q1.

[0032] The switch Q1 is preferably a controllable semiconductor switch, such as for example a metal-oxide gate field effect transistor (also known as MOSFET) or a silicon metal-oxide gate field effect transistor (also known as Si MOSFET) or a silicon carbide metal-oxide gate field effect transistor (also known as SiC MOSFET) or an insulated gate bipolar transistor (also known as IGBT) or a gallium nitride field effect transistor (also known as the acronym GaN FET).

[0033] The switch Ql thus has a control terminal, for example a gate, designed to receive a control voltage V_G to control it, for example relative to a source of the switch QL

[0034] The voltage converter 104 may further be designed to provide one or more other output voltages from the input voltage HV, in addition to the output voltage P16V. The voltage converter 104 is for example designed, as in the illustrated example, to provide a second output voltage P6V which is continuous and for example 6 V. The voltage converter 104 thus comprises an output terminal BP6V having the output voltage P6V with respect to the electrical ground GND1.

[0035] An example of a voltage converter 104 that can be used in the electrical circuit 100 will be described later with reference to [Fig.3].

[0036] The electrical circuit 100 further comprises a driver 106 designed to drive the switch Q1 of the voltage converter 104 in order to implement the voltage conversion. The driver 106 thus comprises a control terminal Bv G having the control voltage V_G with respect to the electrical ground GNDL. An example of a driver 106 that can be used in the electrical circuit 100 will be described later with reference to [Fig.4].

[0037] The driver 106 is electrically powered by the voltage converter 104. For this, the electrical circuit 100 comprises a power supply capacitor C3 of the driver 106, connected to the voltage converter 104 in order to be charged by the output voltage P16V.

[0038] For example, the driver 106 has a power supply terminal BVDd designed to have a power supply voltage VDD and a ground terminal GND connected to the electrical ground GNDL. The power supply capacitor C3 is then connected between the power supply terminal BVdd and the electrical ground GNDL. In addition, the terminal BPi6v of the voltage converter 104 is connected to the power supply terminal BVdd of the driver 106 to charge the capacitor C3. For this, the electrical circuit 100 comprises, for example, a diode D1, and possibly a resistor R14 connected in series, between the output terminal BPi6v of the voltage converter 104 and the power supply terminal BVdd of the driver 106, the diode D1 being conductive to the power supply terminal BVdd. In other words, the diode D1 has an anode connected to the output terminal BPi6v and a cathode connected to the power supply terminal BVDd.

[0039] To power the driver 106 at the start of the electrical circuit 100 when the voltage converter 104 does not yet provide the output voltage P16V, the electrical circuit 100 further comprises a starting circuit 108 designed to electrically power the driver 106 from the input voltage HV. The power supply capacitor C3 is thus connected to the starting circuit 108 which is designed to charge the power supply capacitor C3 from the input voltage HV. For example, the starting circuit 108 has an output terminal BVout having an output voltage VOUT obtained from the input voltage HV, this output terminal BVout being connected to the power supply terminal BVDd of the driver 106, and therefore to the capacitor C3.

[0040] For this, the ignition circuit 108 firstly comprises a voltage divider 110 comprising a so-called high part 112 connected to the voltage source 102 to receive the input voltage HV and a so-called low part 114 connected to the electrical ground GNDL. The voltage divider 110 further comprises a midpoint M to which the high 112 and low 114 parts are connected to each other, the output terminal BVout being connected to the midpoint M, for example via a diode D7.

[0041] The upper part 112 of the voltage divider 110 comprises a capacitor C and a re resistance RI connected in series. Preferably, the capacitance C is made from at least two capacitive components in series and / or at least two capacitive components on two branches in parallel respectively. For example, in [Fig.l], the capacitive components C11 and C12 are in series, as are the capacitive components C13 and C14. In addition, the capacitive components C11 and C12 and the capacitive components C13 and C14 are on two branches in parallel.

[0042] The lower part 114 of the voltage divider 110 comprises for example a Zener diode D6 connected between the midpoint M and the electrical ground GND1 in a conductive manner towards the midpoint M and / or a resistor R15 connected between the midpoint M and the electrical ground GND1. In other words, the Zener diode D6 has an anode connected to electrical ground GND1 and a cathode connected to the midpoint M.

[0043] Where appropriate, the ignition circuit 108 further comprises the diode D7 connected between the midpoint M and the supply capacitor C3, conducting towards the supply capacitor C3 to allow charging of the supply capacitor C3 through the upper part 112 of the voltage divider 110. In other words, the diode D7 has an anode connected to the midpoint M and a cathode connected to the output terminal BVout. The output voltage VOUT is in this case equal to the voltage of the midpoint M, less the voltage drop in the diode D7. The voltage divider 110 is thus designed so that the output voltage VOUT at the output terminal BVout is continuous and lower than the output voltage P16V of the voltage converter 104.

[0044] The ignition circuit 108 may further comprise a diode D2 between the voltage source and the voltage divider 110, conducting towards the latter. In other words, the diode D2 has an anode connected to the input terminal BHV and a cathode connected to the upper part 112 of the voltage divider 110. The ignition circuit 108 may further comprise a resistor RI6 between the voltage source 102 and the electrical ground GND1.

[0045] With reference to [Fig.2], an example of operation of the electrical circuit 100 will now be described.

[0046] Initially, capacitor C and capacitor C3 are discharged.

[0047] At a time t0, the voltage source 102 is activated to provide the input voltage HV.

[0048] Capacitance C and capacitor C3 are charged from the HV input voltage.

[0049] At an instant tl, the Zener diode D6 becomes conductive, at its reverse voltage. Thus, the supply voltage VOUT applied to the supply terminal VDD becomes substantially constant, in the example presented substantially equal to 9.5V, at a level allowing the driver 106 to operate.

[0050] At a time t2, the driver 106, powered only by the voltage VOUT, begins to control the switch Ql, so that the voltage P16V and the voltage P6V start to increase.

[0051] At a time t3, the voltage P16V exceeds the supply voltage VOUT, so that the diode D7 becomes blocked. At this time, the driver 106 is powered by the voltage P16V and the capacitor C3 continues to be charged by the voltage P16V. The capacitor C then continues to charge, until it is charged to a voltage close to the input voltage HV. At this time, the capacitor C has a zero current flowing through it, so that the resistors RI, R15 no longer dissipate energy. Since the heat to be dissipated is reduced, it is possible to use a smaller package. Thus, the capacitor C performs the same function as the switch of the prior art circuit.

[0052] In the example described here, the capacitor C is electrically and physically connected to a support, generally an electronic card.

[0053] If the capacitor C were made by a single component, the latter could, in the event of a fault, go into open circuit. In this case, the ignition circuit 108 could no longer operate. With the capacitor C comprising two capacitive components placed on two branches in parallel, if one of the two branches goes into open circuit, the current can still pass through the other branch.

[0054] Preferably, each of the two capacitive components in series of each of the two branches in parallel has two terminals, for each branch in parallel, the two terminals of one of the two capacitive components define a line perpendicular to a line defined by the two terminals of the other of the two capacitive components.

[0055] In other words, for each of the two branches in parallel, one of the two capacitive components is rotated 90° on the support relative to the other of the capacitive components.

[0056] Thus, if the support is curved, one of the two capacitive components in series will not suffer any deterioration linked to the curvature of the support.

[0057] Alternatively, the two branches extend at 90° to each other on their support.

[0058] Furthermore, if only one capacitive component were provided on each branch, this capacitive component could, in the event of a fault, short-circuit. In this case, the supply voltage VOUT could become equal (at the ready voltage drop across the terminals of diodes D2 and D7) to the input voltage HV, which could damage the driver 106. This problem is avoided by using, on each branch, two capacitive components in series.

[0059] At a time t4, the voltage P16V and the voltage P6V reach their respective setpoint values ​​and are maintained there by the driver 106.

[0060] With reference to [Fig.3], the converter 104 is for example a switching converter such as a flyback converter.

[0061] The converter 104 thus comprises a transformer 302 comprising a primary PI and at least one secondary, for example two secondaries SI, S2 as in the example illustrated. The converter 104 further comprises, for each secondary SI, S2, a capacitor C9, respectively CIO, and a resistor R13, respectively R12, connected to the terminals of the secondary SI, S2 considered, as well as a diode D3, respectively D5, to prevent the capacitor C9, respectively CIO, from discharging into the secondary SI, S2 considered. The output voltages P6V, P16V are thus present respectively on the capacitors C9, CIO.

[0062] The switch Q1 is thus designed to selectively connect and disconnect the primary PI to the voltage source 102, so that the voltage HV is selectively applied or not to the primary PL

[0063] With reference to [Fig.4], an exemplary embodiment of the driver 106 will now be described.

[0064] The driver 106 firstly comprises a microcontroller 402 having the power supply terminal BVdd and the ground terminal GND connected to the electrical ground GND1.

[0065] The microcontroller 402 further has a control terminal GDRV connected to the switch Q1 to control it. For example, the driver 106 comprises a voltage divider bridge comprising two resistors R5, R18 connected to each other at a midpoint and together between the control terminal GDRV and the electrical ground, this midpoint being designed to present the voltage V_G and being connected to the control terminal of the switch Q1.

[0066] The microcontroller 402 is for example self-controlled by an RC circuit 404 (RC meaning “capacitive-resistive”), as in the example illustrated. The RC circuit 404 comprises for example two resistors RI 1, RIO connected to each other at a midpoint and together between the voltage P16V and the electrical ground GND1. The midpoint is connected to a feedback terminal FB (from the English “feedback”) of the microcontroller 402 designed to measure the midpoint voltage as a measurement representative of the voltage P16V in order to control the latter. The RC circuit 404 further comprises, between the midpoint and a compensation terminal COMP of the microcontroller 402, on the one hand, a capacitor C8 and, on the other hand, a capacitor C7 and a resistor R7 in series. These components, together with an internal component of the microcontroller 402, not shown, control the reaction speed of the P16V voltage control loop and thus the stability of this control loop..

[0067] In conclusion, it appears clearly that an electrical circuit such as that described previously does not require a controllable switch in the ignition circuit 108 and therefore a protection circuit for this switch.

[0068] It will also be noted that the invention is not limited to the embodiments described above. It will indeed appear to those skilled in the art that various modi modifications can be made to the embodiments described above, in light of the teaching which has just been disclosed to him.

[0069] In the detailed presentation of the invention which is made above, the terms used must not be interpreted as limiting the invention to the embodiments set out in the present description, but must be interpreted to include all equivalents whose prediction is within the reach of those skilled in the art by applying their general knowledge to the implementation of the teaching which has just been disclosed to them.

Claims

Claims

1. An electrical circuit (100) comprising: - a voltage converter (104) having an input terminal (BHV) and at least one switch (Ql), the voltage converter (104) being designed to provide an output voltage (P16V) when an input voltage (HV) is present on its input terminal (BHv); - a driver (106) designed to drive the switch (Ql) of the voltage converter (104); - a power supply capacitor (C3) of the driver (106), connected to the voltage converter (104) in order to be charged by the output voltage (P 16V); and - a bootstrap circuit (108);characterized in that the starting circuit (108) comprises: - a voltage divider (110) comprising a high part (112) and a low part (114) connected to each other at a midpoint (M), the high part (112) being further connected to the input terminal (BHV) of the voltage converter (104), the high part (112) comprising, in series, a so-called high resistance (RI) and a capacitor (C); and - a diode (D7) connected between the midpoint (M) and the supply capacitor (C3), passing towards the supply capacitor (C3) to allow charging of the supply capacitor (C3) through the high part (112) of the voltage divider (110) to a continuous supply voltage (VOUT) lower than the output voltage (P 16V) of the voltage converter (104).;

2. An electrical circuit (100) according to claim 1, wherein the capacitance (C) comprises two capacitive components in series (C11, C12, C13, C14).

3. Electrical circuit (100) according to claim 1 or 2, in which the capacitance (C) comprises two capacitive components (C11, C12, C13, C14) on two branches in parallel respectively.

4. An electrical circuit (100) according to any one of claims 1 to 3, wherein the lower part of the voltage divider (114) comprises a Zener diode (D6).

5. An electrical circuit (100) according to any one of claims 1 to 4, wherein the lower portion of the voltage divider (114) comprises a resistor (R15).

6. Electrical circuit (100) according to claims 4 and 5, wherein the Zener diode (D6) and the resistor (R15) of the lower part of the voltage divider (114) are respectively on two branches in parallel.

7. An electrical circuit (100) according to any one of claims 1 to 6, wherein the input voltage (HV) is DC and wherein the voltage converter (104) is a DC-DC voltage converter.

8. An electrical circuit (100) according to claim 7, wherein the output voltage (P 16V) is lower than the input voltage (HV).

9. An electrical circuit (100) according to any one of claims 1 to 8, wherein the driver (106) comprises a microcontroller (402) adapted to control the switch (Ql).

10. Mobility device comprising an electrical circuit (100) according to any one of claims 1 to 9.

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