Voltage converter comprising a voltage regulating device

Abstract

The present invention provides a voltage converter (1) comprising at least one switching arm (2) comprising a ground terminal (3), a power supply terminal (4), a first transistor (T1) and a second transistor (T2) arranged in series with each other between the ground terminal and the power supply terminal and a phase terminal (5) arranged between the transistors, the second transistor comprising a second source (S2) connected to the ground terminal and a second drain (D2) connected to the phase terminal. The voltage converter comprises a voltage regulating device connected between the ground terminal and the power supply terminal of the switching arm and configured to generate a voltage between the ground terminal and the power supply terminal in order to maintain the second transistor in the off state. Figure for abstract: Fig. 1

Description

Title of the invention: Voltage converter comprising a voltage regulating device

[0001] The invention relates to a voltage converter, in particular for a rotating electrical machine or for a direct-direct voltage converter.

[0002] The invention finds a particularly advantageous application in the field of rotating electrical machines such as alternators, alternator-starters or even reversible machines or electric motors for electric or hybrid vehicles. It is recalled that a reversible machine is a rotating electrical machine capable of working reversibly, on the one hand, as an electric generator in alternator function and, on the other hand, as an electric motor for example to start the thermal engine of the vehicle such as a motor vehicle.

[0003] The on-board electrical network of the vehicle is used to power the various electrical equipment of the vehicle. An electrical supply from the electrical network is provided by at least one battery, which can be recharged by a rotating electrical machine.

[0004] A rotating electrical machine is connected to a voltage converter and comprises a movable rotor rotating about an axis and a fixed stator. In alternator mode, when the rotor is rotating, it induces a magnetic field in the stator which transforms it into direct electric current via the voltage converter in order to supply the electrical consumers of the vehicle and recharge the battery. In motor mode, the stator is electrically supplied via the voltage converter which functions as an inverter and induces a magnetic field driving the rotor in rotation for example to start the thermal engine.

[0005] The voltage converter comprises a switching arm for each phase of the stator of the rotating electrical machine, i.e. for each winding of the stator. Each switching arm comprises two electrical power components such as transistors each operating as a switch arranged to switch between a blocked state and an on state. The transistors are arranged in series with each other between a positive terminal and a ground terminal, both connected to two terminals of the battery.

[0006] Each switching arm comprises a first transistor called a high side transistor. This high side transistor comprises a drain connected to the positive terminal and a source connected to one of the phases. Each switching arm also comprises a second transistor called a low side transistor or "low side transistor" in English. This low side transistor has a source connected to the ground terminal and a drain connected to the phase. The two transistors in each switching arm are powered by the vehicle's 12V network and via an isolated gate driver connected to both transistors.

[0007] When there is an unexpected rotation of the rotating electrical machine, a voltage rise can be generated between the phases of the stator resulting in an overvoltage between the terminals of the switching arms and therefore also at the terminals of the battery, which can damage it.

[0008] When the voltage converter is at rest, it is known to apply a fault refuge mode consisting of closing the low-side transistors so as to allow the current to flow between the phases of the rotating electrical machine and avoid an overvoltage at the terminals of the battery. A safety state is then obtained.

[0009] To apply this fault refuge mode, the voltage converter comprises an additional so-called redundant power supply connected to a phase control circuit controlling the transistors of all the switching arms and making it possible to apply a voltage of 48V to the phase control circuit to keep the low side transistors of all the switching arms closed.

[0010] This additional power supply is positioned in a control (or logic) zone of the voltage converter, that is to say in a zone comprising control (or logic) components and no power components.

[0011] The power to supply the phase control circuit (three or six phases for example) is high and the voltage can go up to 70V. It is therefore necessary to electrically isolate this additional power supply and the conductive traces associated with it so as not to disturb the control circuits in the control zone operating with lower powers in order not to affect the efficiency of the control components, avoid electromigration of the trace components and avoid dangerous thermal phenomena.

[0012] It is therefore necessary to separate the 48V trace from the low voltage trace by a sufficiently large distance. For example, on a voltage converter with a power of 25 kW, the insulation distance between the 48V trace and the low voltage trace is 3 mm. Given the 48V trace connected to the ground of the electrical network and the 48V trace connected to the positive terminal of the battery, a width of 9 mm is necessary for the two tracks.

[0013] This additional power supply therefore causes a space problem because the traces supplying the 48V voltage then take up a lot of space on the printed circuit.

[0014] Additionally, applying a high current through the transistor bridge with this method may result in a voltage drop across the gate driver supply. This can cause a linear mode on the transistor followed by failure.

[0015] This solution is therefore not ideal because it provides a switching power supply and the 48V power supply is therefore not always available.

[0016] The present invention aims to avoid the drawbacks of the prior art by providing a voltage converter comprising means for closing low-side transistors which is less bulky and improves the safety of the voltage converter and the battery in the event of unwanted stator rotation.

[0017] To this end, the present invention therefore relates to a voltage converter for a rotating electrical machine intended to be electrically connected to an electrical network. The voltage converter comprises at least one switching arm comprising: - a ground terminal intended to be electrically connected to an electrical ground of the electrical network, - a power supply terminal intended to be electrically connected to a positive terminal of the electrical network, - a first transistor and a second transistor each operating as a switch arranged to switch between an off state and an on state, the transistors being arranged in series with each other between the ground terminal and the power supply terminal, and - a phase terminal arranged between the first transistor and the second transistor and intended to be electrically connected to a phase of the rotating electrical machine. The first transistor comprises a first drain connected to the positive terminal and a first source connected to the phase terminal. The second transistor comprises a second source connected to the ground terminal and a second drain connected to the phase terminal.

[0018] According to the present invention, the voltage converter comprises a voltage regulating device connected between the ground terminal and the power supply terminal of the switching arm. The voltage regulating device is configured to generate a voltage between the ground terminal and the power supply terminal adapted to maintain the second transistor in the blocked state.

[0019] The invention thus provides a voltage converter comprising a means for closing the low-side transistors which is less bulky and more efficient than those of the prior art to ensure the safety of the voltage converter and the battery supplying the vehicle's electrical network and therefore the voltage converter.

[0020] According to one embodiment, the voltage converter comprises an isolated gate control supplying the two transistors via two respective control modules. Each transistor comprises a gate connected to one of the control modules. The voltage converter comprises a power zone in in which the two control modules and the voltage regulation device are positioned.

[0021] It is thus possible to apply high power to supply the control circuit of three phases or six phases, for example, without affecting the efficiency of the control components in the control area.

[0022] According to another embodiment, the isolated gate control comprises an electrically isolated portion on which the voltage regulating device is positioned.

[0023] The voltage regulating device is closest to the isolated gate control.

[0024] According to another embodiment, the voltage delivered by the voltage regulation device is at least 24V. It is preferably 48V.

[0025] Indeed, the voltage delivered by the voltage regulation device must be higher than the supply voltage of the gate of a MOSFET transistor which is approximately 15V. Nominal operation is not permitted below 24V and power limitation operation is not possible below 20V.

[0026] The invention thus provides a 48V power supply that is always available. Voltage drops caused by the additional 48V power supply according to the prior art are also avoided. The stability of the transistor is increased by avoiding a linear mode on the transistor.

[0027] The invention also solves a problem of space requirement compared to the solutions of the prior art in which the traces conducting the 48V voltage take up a lot of space on the printed circuit to avoid electromigration of the components of the traces and dangerous thermal phenomena. It is no longer necessary to separate or isolate the 48V trace from the low voltage trace by a sufficiently large distance.

[0028] According to another embodiment, the voltage converter comprises an OR logic circuit connected between the voltage regulating device and the isolated gate driver. The OR logic circuit is connected to the electrical network.

[0029] Preferably, the voltage converter comprises three switching arms each comprising a voltage regulating device connected between a ground terminal and a power supply terminal of the respective switching arms.

[0030] Thus, if one of the voltage regulating devices does not work, the others are operational to ensure the safety of the voltage converter. Closing all six phases instead of all six is ​​sufficient to keep the overvoltage below a critical voltage threshold.

[0031] According to another embodiment, the voltage converter comprises an additional voltage regulating device connected to a control circuit of the phases and configured to generate a voltage between the ground terminal and the supply terminal of the switching arm or each switching arm if the voltage converter includes three switching arms. The phase control circuit is connected to the gate drive. The additional voltage regulating device is positioned in a control area.

[0032] This solution makes it possible to increase the safety of the voltage converter.

[0033] According to another embodiment, the voltage converter comprises several switching arm of which at least two switching arms are powered by a voltage regulating device. The voltage regulating device is connected between each ground terminal and each power supply terminal of the two respective switching arms.

[0034] This solution makes it possible to simplify and reduce the cost of the voltage converter.

[0035] The present invention also relates to an electrical assembly comprising a rotating electrical machine connected to a voltage converter as defined previously.

[0036] The present invention also relates to a method for protecting a switching arm of a voltage converter of a rotating electrical machine as defined above and intended to be electrically connected to an electrical network.

[0037] According to the invention, the voltage regulating device generates a voltage between the ground terminal and the supply terminal of the switching arm adapted to maintain the second transistor in the blocked state.

[0038] The present invention may be better understood by reading the detailed description which follows, non-limiting examples of implementation of the invention and by examining the single attached drawing.

[0039] [Fig.l] represents, schematically and partially, a voltage converter connected to an electrical network of a vehicle, according to an exemplary implementation of the invention.

[0040] The embodiments described below are in no way limiting. In particular, it is possible to imagine variants of the invention comprising only a selection of features described below isolated from the other features described. In particular, all the variants and all the embodiments described can be combined with each other if nothing prevents this combination from a technical point of view.

[0041] [Fig.l] represents an example of a voltage converter 1 for a polyphase rotating electrical machine (not shown), in particular for a vehicle such as an electric or hybrid motor vehicle, connected to an electrical network powered by a battery 15.

[0042] The rotating electrical machine is connected to the battery 15 via a positive terminal B+ and an electrical ground GND of the electrical network.

[0043] According to a variant, this rotating electrical machine transforms mechanical energy into electrical energy and therefore supplies the electrical network via terminal B+ with direct current, in alternator mode, and can also operate in motor mode to transform electrical energy into mechanical energy while being supplied by the electrical network via the positive terminal B+.

[0044] This rotating electrical machine is, for example, an alternator, an alternator-starter, a reversible machine or an electric motor. The machine can be of the synchronous or asynchronous type.

[0045] In this example, the rotating electrical machine comprises a housing on which the voltage converter 1 is mounted. Alternatively, the voltage converter 1 can be remote from the rotating electrical machine or mounted inside the housing.

[0046] Inside this housing, the rotating electrical machine comprises a rotor integral in rotation with a shaft and a stator. The rotor may for example be a claw rotor comprising two pole wheels and an electric coil or be formed from a stack of laminations housing permanent magnets or even a squirrel cage rotor. The stator may comprise a body on which an electric winding is mounted. The winding is formed from one or more phases, also called an electric winding, comprising at least one electric conductor. The winding may be of the corrugated or concentric type and may be formed by one or more electric wires or by a plurality of conductive segments in the form of a bar or a pin.

[0047] The rotating electrical machine is electrically interfaced via the voltage converter 1 to the electrical network.

[0048] In the example illustrated in [Fig.l], the electrical winding comprises three electrical phases connected to three phase terminals 5 of the voltage converter 1. The voltage converter 1 therefore comprises three switching arms 2 each comprising a phase terminal 5.

[0049] Alternatively, the electrical winding could comprise another number of electrical phases such as five or six electrical phases. Each phase has one end forming a phase output which is electrically connected to the voltage converter 1 via the three phase terminals 5.

[0050] Each switching arm 2 comprises a ground terminal 3 electrically connected to the electrical ground GND of the electrical network and a power supply terminal 4 electrically connected to the positive terminal B+ of the electrical network.

[0051] Each switching arm 2 also comprises a first transistor T1 and a second transistor T2 each operating as a switch arranged to switch between a blocked state and an on state. The transistors T1, T2 are arranged in series with each other between the ground terminal 3 and the power supply terminal 4.

[0052] In the off state, the switch is open and the electric current does not flow through the transistor T1, T2. In the on state, the switch is closed and the electric current flows through the transistor T1, T2. The on state may correspond to a deliberately on state when the transistor T1, T2 is driven or an involuntarily on state when a failure of the transistor T1, T2 causes a short circuit of said transistor T1, T2.

[0053] According to one embodiment, the first and second transistors T1, T2 are field effect transistors, in particular of the MOSFET type (English acronym for “Metal Oxide Semiconductor Field Effect Transistor”).

[0054] The phase terminal 5 is arranged between the first transistor T1 and the second transistor T2 and is electrically connected to a phase or electrical winding of the rotating electrical machine.

[0055] The first transistor T1 is called a high side transistor. The first transistor T1 comprises a first drain DI connected to the positive terminal B+ and a first source SI connected to one of the phases via the phase terminal 5.

[0056] The second transistor T2 is called the low side transistor. The second transistor T2 comprises a second source S2 connected to the ground terminal 3 and a second drain D2 connected to this same phase via the phase terminal 5.

[0057] The two transistors T1, T2 of each switching arm 2 are powered by the 12V network of the vehicle and by means of an insulated gate control 7 connected to the two transistors T1, T2.

[0058] The voltage converter 1 comprises an isolated gate control 7 driving the two transistors T1, T2 via two respective control modules 11, 12 including a first control module 11 and a second control module 12. The first transistor T1 comprises a first gate G1 connected to the first control module 11. The second transistor T2 comprises a second gate G2 connected to the second control module 12.

[0059] The control modules 11, 12 make it possible to control the two transistors T1, T2 between the on state and the off state.

[0060] The voltage converter 1 comprises three insulated gate drives 7 each controlling a separate switching arm 2. The three insulated gate drives 7 are controlled by a phase control circuit 10.

[0061] The voltage converter 1 comprises three distinct power zones 13.

[0062] These power zones 13 are called thus because they each comprise the two transistors T1, T2 which are power components and traces or tracks conducting high powers.

[0063] According to the invention, the voltage converter 1 comprises at least one voltage regulating device 6 connected between the ground terminal 3 and the power supply terminal 4 of the switching arm 2. The voltage regulating device 6 is configured to generate a voltage between the ground terminal 3 and the supply terminal 4 suitable for maintaining the second transistor T2 in the off state.

[0064] The battery 15 provides a primary power supply and the voltage regulating device 6 provides a secondary power supply.

[0065] In the example of [Fig.l], the voltage converter 1 comprises three voltage regulating devices 6. Each of the three voltage regulating devices 6 is connected between the ground terminal 3 and the power supply terminal 4 of one of the three switching arms 2.

[0066] In other words, the voltage converter 1 comprises a first voltage regulating device supplying or protecting a first switching arm. The voltage converter 1 comprises a second voltage regulating device supplying or protecting a second switching arm. And the voltage converter 1 comprises a third voltage regulating device supplying or protecting a third switching arm.

[0067] The two control modules 11, 12 and the voltage regulation device 6 associated with each switching arm 2 are positioned in the power zone 13.

[0068] Each insulated gate driver 7 comprises an electrically insulated portion (or side) 8. Preferably, each voltage regulating device 6 is positioned on each electrically insulated portion 8.

[0069] The electrically insulated part 8 of the insulated gate control 7 makes it possible to protect it from the high intensity currents associated with the transistors T1, T2.

[0070] Several isolation solutions are possible. Preferably, the electrically isolated part 8 comprises an isolator which modulates the useful signal with a high-frequency carrier through a pair of transmitting and receiving antennas. The electrically isolated part 8 has its own power supply means in order to reproduce the input signal via a cascade electronic voltage amplifier assembly or "push pull" in English. Alternatively, this electrically isolated part 8 can be completely floating. The signal is then sent to a gate circuit comprising resistors and diodes in order to adjust the switching on or off of the MOSFET transistor.

[0071] For example, the voltage delivered by the voltage regulating device 6 is at least 24V. It is preferably equal to 48V.

[0072] According to one embodiment, the voltage converter 1 comprises three OR logic circuits 9. Each OR logic circuit 9 connects one of the voltage regulating devices 6 to one of the three insulated gate controls 7. Each OR logic circuit 9 is also connected to the electrical network and therefore to the battery 15.

[0073] The voltage regulating device 6 is powered by the battery 15 under a voltage of 12V and amplifies this voltage to 48V.

[0074] The logic circuit OR 9 operates in two modes. In a first mode, it gives priority to the power supply coming from the 12V network because it is the main power supply.

[0075] According to a second mode of operation, in the event of failure of the 12V main power supply, the OR logic circuit 9 allows the 48V secondary power supply, generated by the voltage regulating device 6, to take over. Normally, the operating range of the main power supply is greater than the operating range of the secondary power supply.

[0076] When the voltage converter 1 is at rest (electrical machine not powered), the three voltage regulating devices 6 and the three OR logic circuits 9 make it possible to deliver a voltage of 48V between the ground terminal 3 and the power supply terminal 4 of each switching arm 2 so as to maintain the three second transistors T2 in the blocked state. In the event of an overvoltage caused by the rotation of the rotor of the electric machine, the current cannot flow through the second transistor T2 (or low-side transistor) to damage the battery 15 which is thus protected.

[0077] The voltage regulating devices 6 are also called additional or redundant power supplies and make it possible to apply a fault refuge mode allowing the current to flow between the phases of the rotating electrical machine and to avoid an overvoltage at the terminals of the battery 15 in the event of unplanned or desired rotation of the rotor of the rotating electrical machine. A safe state is then obtained for the voltage converter 1.

[0078] Thus, if one of the voltage regulation devices 6 is faulty, the other voltage regulation devices 6 still ensure the safety of the battery 15.

[0079] According to another variant not shown, the voltage converter 1 further comprises an additional voltage regulating device connected to the phase control circuit 10. The additional voltage regulating device is configured to also generate a voltage of 48V between the ground terminal 3 and the power supply terminal 4 of each switching arm 2 simultaneously.

[0080] The additional voltage regulation device also makes it possible to close the second transistors T2 of the three switching arms 2 so as to allow the current to flow between the phases of the rotating electrical machine and avoid an overvoltage at the terminals of the battery 15. An additional safety state is then obtained.

[0081] The additional voltage regulation device is positioned in a control (or logic) zone 14 of the voltage converter 1 which is different from the power zone 13. The control zone 14 comprises control (or logic) components and not power components such as transistors.

[0082] According to another embodiment not shown, the voltage converter 1 comprises several switching arms 2 including at least two switching arms 2 supplied by a voltage regulation device 6. The voltage regulation device 6 is connected between each ground terminal 3 and each power supply terminal 4 of the two respective switching arms 2.

[0083] In other words, a voltage regulating device 6 supplies two switching arms 2 with 48V.

[0084] For example, the voltage converter 1 comprises six switching arms 2 including a first switching arm, a second switching arm, a third switching arm, a fourth switching arm, a fifth switching arm and a sixth switching arm.

[0085] The voltage converter 1 then comprises three voltage regulating devices 6 including a first voltage regulating device connected between the ground terminals and the power supply terminals of the first switching arm and between the ground terminals and the power supply terminals of the second switching arm.

[0086] A second voltage regulating device is connected between the ground terminals and the power supply terminals of the third switching arm and between the ground terminals and the power supply terminals of the fourth switching arm.

[0087] A third voltage regulating device is connected between the ground terminals and the power supply terminals of the fifth switching arm and between the ground terminals and the power supply terminals of the sixth switching arm.

[0088] The present invention finds applications in particular in the field of voltage converters for alternators or reversible machines or electric motors, but it could also be applied to any type of rotating machine.

[0089] Of course, the preceding description has been given by way of example only and does not limit the scope of the present invention, which would not be departed from by replacing the various elements with any other equivalents. For example, embodiments comprising electronic components for performing the desired functions have been described previously. The scope of the invention would not be departed from by replacing these components with software applications for performing the same functions.

Claims

Claims

1. Voltage converter (1) for a rotating electrical machine intended to be electrically connected to an electrical network, the voltage converter (1) comprising at least one switching arm (2) comprising: - a ground terminal (3) intended to be electrically connected to an electrical ground (GND) of the electrical network, - a power supply terminal (4) intended to be electrically connected to a positive terminal (B+) of the electrical network, - a first transistor (Tl) and a second transistor (T2) each operating as a switch arranged to switch between a blocked state and an on state, the transistors (Tl, T2) being arranged in series with respect to each other between the ground terminal (3) and the power supply terminal (4), and - a phase terminal (5) arranged between the first transistor (T1) and the second transistor (T2) and intended to be electrically connected to a phase of the rotating electrical machine, the first transistor (T1) comprising a first drain (D1) connected to the positive terminal (B+) and a first source (SI) connected to the phase terminal (5), the second transistor (T2) comprising a second source (S2) connected to the ground terminal (3) and a second drain (D2) connected to the phase terminal (5), characterized in that it comprises a voltage regulating device (6) connected between the ground terminal (3) and the supply terminal (4) of the switching arm (2), the voltage regulating device (6) being configured to generate a voltage between the ground terminal (3) and the supply terminal (4) suitable for maintaining the second transistor (T2) in the blocked state.

2. Voltage converter (1) according to claim 1, characterized in that it comprises an insulated gate control (7) supplying the two transistors (Tl, T2) via two respective control modules (11, 12), each transistor (Tl, T2) comprising a gate (Gl, G2) connected to one of the control modules (11, 12), the voltage converter (1) comprising a power zone (13) in which the two control modules (11, 12) and the voltage regulating device (6).

3. Voltage converter (1) according to claim 3, characterized in that the insulated gate driver (7) comprises an electrically insulated part (8) on which the voltage regulating device (6) is positioned.

4. Voltage converter (1) according to any one of claims 1 to 3, characterized in that the voltage delivered by the voltage regulating device (6) is at least 24V and preferably 48V.

5. Voltage converter (1) according to any one of claims 2 to 4, characterized in that it comprises an OR logic circuit (9) connected between the voltage regulating device (6) and the insulated gate control (7), the OR logic circuit (9) being connected to the electrical network.

6. Voltage converter (1) according to any one of claims 1 to 5, characterized in that it comprises three switching arms (2) each comprising a voltage regulating device (6) connected between a ground terminal (3) and a supply terminal (4) of the respective switching arms (2).

7. Voltage converter (1) according to any one of claims 1 to 5, characterized in that it comprises several switching arms (2) including at least two switching arms (2) supplied by a voltage regulating device (6), the voltage regulating device (6) being connected between each ground terminal (3) and each supply terminal (4) of the two respective switching arms (2).

8. Voltage converter (1) according to any one of claims 1 to 7, characterized in that it comprises an additional voltage regulating device connected to a phase control circuit (10) and configured to generate a voltage between the ground terminal (3) and the supply terminal (4) of the switching arm (2), the phase control circuit (10) being connected to the gate control (7), the additional voltage regulating device being positioned in a control zone (14).

9. Electrical assembly comprising a rotating electrical machine connected to a voltage converter (1) as defined according to any one of claims 1 to 8 and intended to be electrically connected to an electrical network.

10. Method for protecting a switching arm (2) of a voltage converter (1) of a rotating electrical machine according to any one of claims 1 to 8 intended to be electrically connected to a electrical network, characterized in that the voltage regulating device (6) generates a voltage between the ground terminal (3) and the supply terminal (4) of the switching arm (2) adapted to maintain the second transistor (T2) in the blocked state.

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