Chain of electrical modules for powering a rotating electrical machine

Abstract

A chain (30) of modules (10) for an electrical circuit (100) comprising a first terminal (37a) and a second terminal (37b), each module (10) comprising: - a primary terminal (11a) and a secondary terminal (11b), the primary terminal (11a) being connected to the secondary terminal (11b) of another module (10) and / or the secondary terminal (11b) is connected to the primary terminal (11a) of another module (10) - an electrical energy storage unit (12), and - an H-shaped switching bridge (13), the bridge (13) comprising two switching arms comprising two controllable switches (14a, 14b, 14c, 14d) arranged on either side of a midpoint (13a, 13b), each midpoint (13a, 13b) being connected to one of the terminals (11a, 11b) of the module (10), the electrical energy storage unit (12) being arranged in a branch in parallel with the switching arms, this branch being devoid of switches,Characterized in that all or part of the modules (10) comprise a bidirectional switching cell arranged between their primary terminal (11a) and their secondary terminal (11b), this switching cell comprising at least one controllable semiconductor switch (15, 16a, 16b). Abstract figure: [Fig. 1a],

Description

Title of the invention: Chain of electrical modules for supplying a rotating electrical machine

[0001] The present application refers to a chain of modules for a power supply circuit of a rotating electrical machine for propelling a vehicle.

[0002] In a known example, in particular from application US8395280B2, such a chain of modules comprises a first terminal and a second terminal, each module comprising:

[0003] - a primary terminal and a secondary terminal, the primary terminal being connected to the secondary terminal of another module and / or the secondary terminal is connected to the primary terminal of another module

[0004] - an electrical energy storage unit, and

[0005] - an H-shaped switching bridge, the bridge comprising two switching arms comprising two controllable switches arranged on either side of a midpoint, each midpoint being connected to one of the terminals of the module, the electrical energy storage unit being arranged in a branch in parallel with the switching arms.

[0006] These circuits employing a plurality of chains have the disadvantage of having to mobilize a large number of controllable switches which may be victims of malfunction, for example a short circuit. A module having a malfunctioning switch may cause a vehicle employing such a circuit to come to a complete standstill.

[0007] There is a need to address this problem.

[0008] The invention aims to meet this need and achieves this through one of its aspects, thanks to a chain of modules for an electrical circuit comprising a first terminal and a second terminal, each module comprising

[0009] - a primary terminal and a secondary terminal, the primary terminal being connected to the secondary terminal of another module and / or the secondary terminal is connected to the primary terminal of another module

[0010] - an electrical energy storage unit, and

[0011] - an H-shaped switching bridge, the bridge comprising two switching arms comprising two controllable switches arranged on either side of a midpoint, each midpoint being connected to one of the terminals of the module, the electrical energy storage unit being arranged in a branch in parallel with the switching arms, this branch being devoid of switches,

[0012] characterized in that all or part of the modules comprise a bidirectional switching cell arranged between their primary terminal and their secondary terminal, this switching cell comprising at least one controllable semiconductor switch.

[0013] The presence of this switching cell between the terminals of the modules makes it possible to achieve redundancy when it is desired to disconnect the energy storage unit of one of the modules from the rest of the chain. Thus, if the switching cell of said module is defective, it is possible to disconnect the energy storage unit from this module by controlling the switches of the switching bridge, and if one or more switches of the switching bridge are defective, it is possible to functionally disconnect the energy storage unit from the rest of the chain by controlling the switching cell between the terminals of the module. This redundancy can make a circuit using a chain of modules such as described more resistant to malfunctions, extend its service life, and meet a safety requirement for the user of the vehicle.

[0014] According to the invention, the modules are arranged within the chain in such a way that their primary terminal is connected to the secondary terminal of another module and their secondary terminal is connected to the primary terminal of another module, with the exception of a module whose primary terminal is connected to the first terminal of the chain and a module whose secondary terminal is connected to the second terminal of the chain.

[0015] The energy storage unit within the modules is arranged in a branch being devoid of switches. In other words, the electrical energy storage unit is mounted between two nodes of the electrical circuit of the module and is not in series between these two nodes with any switch.

[0016] Each switching cell may comprise a bidirectional transistor, in particular a four-quadrant Gallium Nitride (GaN) power transistor.

[0017] Alternatively, each switching cell comprises two unidirectional transistors mounted in antiparallel, in particular MOS field effect transistors or bipolar transistors.

[0018] The antiparallel connection of two unidirectional transistors can allow two unidirectional transistors driven in the closed position to be able to form a bidirectional structure in current and voltage. For example, two MOS field effect transistors mounted in antiparallel connected to each other by their source, driven in the closed position form a bidirectional structure in current and voltage.

[0019] Alternatively, each cell comprises a microelectromechanical system switch.

[0020] The switching cell between the primary terminal and the secondary terminal is different from a mechanical relay.

[0021] The switching cell and switching bridge of all modules may have switches of the same type.

[0022] The first and second terminals can define the single output voltage of the chain.

[0023] This means that there is no intermediate output terminal within the chain, i.e. an output terminal connected both to the primary terminal of a first module and to the secondary terminal of another module in the chain, this primary terminal and this secondary terminal being connected together.

[0024] The electrical energy storage unit within the modules may have a nominal voltage of between 3 and 60V. For example, the nominal voltage of the electrical energy storage unit may be 5, 12, 24 or 48V.

[0025] Other nominal voltage values ​​are possible, notably greater than 60V.

[0026] The electrical energy storage unit may be a cell of a lithium-ion type cell battery.

[0027] The switching cell of each module can be carried by an electronic card, this electronic card carrying the switches of said module.

[0028] The invention also relates, according to one of its aspects, to an electrical circuit for supplying a rotating electrical machine for propelling a vehicle comprising:

[0029] - a polyphase electric machine,

[0030] - an input interface capable of being connected to a charging station,

[0031] - a plurality of strings of electrical modules, each string being as described previously,

[0032] - a system of switches allowing each chain to be connected to the terminals of a phase of the electrical machine or at the input interface, and

[0033] - a control unit, capable of controlling the switches within the electrical circuit.

[0034] The control unit can be configured to disconnect from the rest of the chain the electrical energy storage unit of a module comprising a switching cell by controlling the at least one switch of said cell to be in the closed position.

[0035] The control unit can be configured to disconnect the electrical energy storage unit from a module comprising a switching cell by also controlling the switches of the switching bridge of said module, the switches connected to the same potential of the energy storage unit being controlled to be in the open position, the others to be in the closed position.

[0036] The number of chains implemented in the plurality of chains may be greater than or equal to the number of phases of the rotating electrical machine.

[0037] The switch system can allow each string of the plurality of strings to be connected to the terminals of a phase of the electrical machine to which this string is dedicated. In other words, a given string can only be connected to a single phase of the stator of the electrical machine.

[0038] The rotating electrical machine is for example a synchronous machine, for example a three-phase synchronous machine or a synchronous machine whose stator electrical winding defines a double three-phase system. The stator electrical winding is for example formed by wires or by conductive bars connected to each other.

[0039] In all of the above, the rotor may be a claw rotor. This rotor then comprises a first and a second nested pole wheels, the first pole wheel defining a series of claws of generally trapezoidal shape, each claw extending axially towards the second pole wheel, the second pole wheel defining a series of claws of generally trapezoidal shape, each claw extending axially towards the first pole wheel. A permanent magnet may be received between two consecutive claws circumferentially speaking for the rotor.

[0040] Alternatively, the rotor may be other than a claw rotor, for example comprising a stack of laminations or being a cage rotor.

[0041] When the rotating machine is a synchronous machine, it may have a wound rotor or a permanent magnet rotor.

[0042] The rotating electrical machine may have a rated electrical power of 25kW, 100kW, 200kW, or more.

[0043] The circuit control unit may be single or comprise a main control unit and several subsidiary control units, for example one subsidiary control unit per chain in the circuit and / or one subsidiary control unit per module.

[0044] The electrical circuit may be reversible, i.e. the switches within the circuit may be controlled so that the strings of modules supply an alternating voltage across the input interface.

[0045] The invention may be better understood by reading the following description of non-limiting examples of its implementation:

[0046] [Fig.1a] represents a first embodiment of a module intended to be implemented within a chain of electrical modules of a circuit for supplying a rotating electrical machine.

[0047] [Fig.lb] represents a second embodiment of a module intended to be implemented within a chain of electrical modules of a circuit for supplying a rotating electrical machine.

[0048] [Fig.2a] represents a chain of modules according to [Fig.1a] or 1b,

[0049] [Fig.2b] represents an example of output voltage of a string of modules according to [Fig.2a] for the power supply of an electric machine.

[0050] [Fig.2c] represents an example of input voltage of a string of modules according to [Fig.2a] allowing the electrical energy storage units within the modules to be charged.

[0051] [Fig.3] represents a circuit for supplying a rotating electrical machine for propelling a vehicle, using a plurality of module chains according to [Fig.2a].

[0052] [Fig. 1a] shows a first embodiment of a module 10 intended to be implemented within a chain of electrical modules of a circuit for powering a rotating electrical machine.

[0053] The module 10 as shown in [Fig. 1a] comprises a primary terminal 11a and a secondary terminal 11b, the voltage between terminals 11a and 11b being denoted Vm.

[0054] The module 10 also comprises an electrical energy storage unit 12, with a nominal voltage Vc. This electrical energy storage unit may be a cell of a battery employing a plurality of cells, and may have a nominal voltage of between 3 and 60V for example. This energy storage unit 22 is arranged in a branch in parallel with a switching bridge 13, this branch not comprising any switches. This switching bridge 13 is mounted in an H-shape and comprises controllable switches 14a, 14b, 14c, 14d, arranged on either side of the midpoints 13a and 13b. In the example shown in [Fig.1a], the switches 14a, 14b, 14c, 14d are MOS field effect transistors.

[0055] In [Fig.1a], the module 10 comprises between its primary terminal 11a and its secondary terminal 11b a switching cell, being in this example the switch 15. This switch 15 is a four-quadrant Gallium Nitride (GaN) power transistor, this transistor 15 being bidirectional.

[0056] When a control unit controls the switches of the switching bridge 13 such that the switches 14b, 14c, 15 are in the open position and the switches 14a, 14d are in the closed position, the voltage Vm between the terminals 11a and 11b of the module 10 is equal to Vc. When the switches 14a, 14d, 15 are in the open position and the switches 14b, 14c are in the closed position, the voltage Vm between the terminals 11a and 11b of the module 10 is equal to -Vc.

[0057] When a control unit controls the switch 15 to be in the closed position, the voltage Vm between the terminals 11a and 11b of the module 10 is zero. A control unit can additionally control the switches 14a, 14b to be in the open position and the switches 14c, 14d to the closed position, or control the switches 14a, 14b to be in the closed position and the switches 14c, 14d to the open position.

[0058] The presence of the switch 15 makes it possible to functionally disconnect the energy storage unit 12 from the module 10 in a simple manner, by controlling only the switch 15, or in a more robust manner by also controlling the switches of the switching bridge 13 of the module 10.

[0059] In the example shown in [Fig.1a], disconnecting the energy storage unit 12 by controlling both the switch 15 and the switches 14a, 14b, 14c, 14d of the switching bridge 13 is advantageous because it makes it possible to provide redundancy for the disconnection of the storage unit 12, and to ensure that the storage unit 12 is disconnected even if some of the switches 14a, 14b, 14c, 14d of the switching bridge 13 or the switch 15 are malfunctioning, for example because they are stuck in the open position or because they are short-circuited.

[0060] In this same example, disconnecting the energy storage unit 12 by controlling only the switch 15 is advantageous in the case where all the switches 14a, 14b, 14c, 14d of the switching bridge 13 are functional and more particularly in the case where the current cannot flow within the switching bridge 13, the current then only flowing through the single switch 15, thus reducing the conduction losses.

[0061] In a variant shown in [Fig.lb], the module 10 is identical to the module 10 of [Fig.la], except that two unidirectional transistors 16a 16b constitute the switching cell arranged between the terminals 11a, 11b. The switches 16a 16b are identical and are N-type MOS field effect transistors, of the same type as the switches 14a, 14b, 14c, 14d of the switching bridge 13.

[0062] In [Fig.lb] transistor 16a is connected by its source to the source of transistor 16b. This so-called antiparallel arrangement allows the current to flow bidirectionally through the two transistors 16a 16b when these two transistors are driven to be in the closed position. These two transistors 16a and 16b of module 10 can be driven together in the same way as transistor 15 of module 10 of [Fig. la] would be driven in order to obtain a voltage between terminals 11a and 11b equal to Vc, -Vc or zero.

[0063] The variant shown in [Fig.lb] is advantageous because the implementation of such a module 10 is facilitated by the use of more common and less expensive unidirectional transistors 16a 16b.

[0064] In [Fig.2a] a chain 30 of four modules 31, 32, 33, 34 is shown. In this example each module is identical and according to any one of the modules 10 shown in Figures 1a and 1b. The modules 31, 32, 33, 34 are chained together by their primary and secondary terminals between the two terminals 37a 37b of the chain. More precisely, the module 31 is connected to the first terminal 37a of the chain 30 by its primary terminal and to the primary terminal of the module 32 by its secondary terminal, the module 32 is connected to the primary terminal of the module 33 by its secondary terminal, the module 33 is connected to the primary terminal of the module 34 by its secondary terminal and the module 34 is connected to the second terminal 37b of the chain 30 by its secondary terminal.

[0065] The chain 30 has a single output voltage which is defined between its two terminals 37a and 37b. Regardless of the value that can be taken by this output voltage, it will be designated Vs hereinafter. In the example shown in Figure 2, the electrical energy storage units within the four modules 31, 32, 33, 34 being identical and of nominal voltage Vc, the voltage Vs can take as a value all the positive or negative integer multiples of Vcentre -4*Vc and 4*Vc when these electrical energy storage units are capable of supplying a voltage.

[0066] [Fig.2b] shows a graph 35 representing an example of an alternating voltage generated Vs by the module chain 30 shown in [Fig.2a]. This generated alternating voltage Vs is capable of powering a rotating electrical machine, it is periodic with a period Ti and its shape is comparable to a sine wave.

[0067] At times 0, tb t2, and t3, the modules 31, 32, 33, 34 of the chain 30 are controlled successively so that the voltage between their terminals is equal to Vc, the maximum voltage of the generated alternating voltage Vs between two successive times becoming equal to Vc, 2* Vc, 3* Vc and 4*VC respectively. By controlling a module, we mean controlling the switches within said module in order to obtain the desired voltage between its terminals.

[0068] At times t4, t5, t6 the modules 31, 32, 33, 34 of the chain 30 are controlled successively so that the voltage between their terminals is equal to 0, the maximum voltage of the generated alternating voltage 35 between two successive times becoming equal to 3*VC, 2* Vc and Vc respectively.

[0069] The time interval between instants 0 and t7 corresponds to the positive part of the period Ti of the alternating voltage 35.

[0070] The order of control of the modules 31, 32, 33, 34 between times 0 and t7 may correspond for example to the state of charge of the electrical energy storage unit within the modules 31, 32, 33, 34. In order to balance the state of charge of the energy storage units contained in the modules 31, 32, 33, 34, the modules may for example, be controlled at times 0, tb t2, and t3 according to the decreasing order of charge state of their electrical energy storage unit and the increasing order at times t4, t5, t6 and t7. Thus the storage unit being the most charged among the modules will be discharged for a longer time and the least charged storage unit will be discharged for a shorter time, extending the autonomy of the chain.

[0071] At times t7, t8, t9, and ti0, the modules 31, 32, 33, 34 of the chain 30 are controlled successively so that the voltage between their terminals is equal to -Vc, the maximum voltage of the generated alternating voltage 35 between two successive times becoming equal to -Vc, -2* Vc, -3* Vc and -4*VC respectively. At times tu, ti2, and tn, modules 31, 32, 33, 34 of the chain 30 are controlled successively so that the voltage between their terminals is equal to 0, the maximum voltage of the generated alternating voltage 35 between two successive times becoming equal to -3*VC, -2* Vc and -Vc respectively.

[0072] The time interval between instants t7 and tM corresponds to the negative part of the period Ti of the alternating voltage Vs.

[0073] The order of control of the modules 31, 32, 33, 34 between the times t7 and tn may correspond for example to the state of charge of the electrical energy storage unit within the modules 31, 32, 33, 34, 35. In order to balance the state of charge of the energy storage units contained in the modules 31, 32, 33, 34, the modules may for example be controlled according to the decreasing order of state of charge of their electrical energy storage unit between the times t7, t8, t9, and ti0 and the increasing order at the times tu, ti2, and t13.

[0074] Between two successive instants, a module can be controlled so that the voltage between its terminals successively changes from Vc to 0 and vice versa during the positive part of the period Ti or -Vc to 0 and vice versa during the negative part of the period Tb, for example by pulse width modulation. This makes it possible to reduce the harmonic distortions of the generated alternating voltage 35.

[0075] The time intervals between two successive instants 0, tl, t2, t3, etc. may be all or partially identical.

[0076] [Fig.2c] shows a graph 37 representing an example of charging of the energy storage units within the modules of the chain 30 shown in [Fig.2a] when an alternating voltage Vs is applied to the terminals of said chain.

[0077] The voltage Vs shown in [Fig.2c] is a sinusoidal alternating voltage suitable for being applied to the terminals 37a 37b of the chain 30 of Figure 2. In the example shown, the voltage Vs has a maximum voltage and a minimum voltage of 4*Vcet and -4*Vcrespectively, and is periodic with a period T2. This alternating voltage can come from a charging station, connected to the terminals of the chain 30.

[0078] In the example shown in [Fig.2c], during the time interval 41 between the instant O and the instant t26, the instants when the voltage Vs is zero, a module of the chain 30, for example the module 31, is controlled so that the voltage between its terminals is equal to Vc. As a result, during the time interval 41 the electrical energy storage unit of the module 31 is charged. During the time interval 42 between the instant t20 and the instant t25, the instants when the voltage 37 is equal to Vc, another module of the chain 30, for example the module 32, is controlled so that the voltage between its terminals is equal to Vc. As a result, during the time interval 42 the electrical energy storage unit of the module 32 is charged.During the time interval 43 between the instant t2i and the instant t24, the instants when the voltage 37 is equal to 2*VC, another module of the chain 30, for example the module 33, is controlled so that the voltage between its terminals is equal to Vc. As a result, during the time interval 43 the electrical energy storage unit of the module 33 is charged. During the time interval 44 between the instant t22 and the instant t23, the instants when the voltage 37 is equal to 3*VC, another module of the chain 30, for example the module 34, is controlled so that the voltage between its terminals is equal to Vc. As a result, during the time interval 44 the electrical energy storage unit of the module 34 is charged.

[0079] Similarly, during the time intervals 45, 46, 47 and 48, during the negative half-period of the period T2 of the alternating voltage Vs, the modules 31, 32, 33, 34 of the chain 30 are successively controlled so that the voltage between their primary and secondary terminals is equal to -Vcentre at the times when the alternating voltage Vs is equal to 0, -Vc, -2*VC and -3*Vc respectively so that their respective electrical energy storage unit is charged during these respective time intervals.

[0080] The order of control of the modules 31, 32, 33, 34 may correspond for example to the state of charge of the electrical energy storage unit within the modules 31, 32, 33, 34. In order to balance the state of charge of the electrical energy storage units contained in the modules 31, 32, 33, 34, the modules may for example be charged during the intervals 41, 42, 43, 44 respectively according to the increasing order of state of charge of their electrical energy storage unit. Thus, the most discharged electrical energy storage unit will be charged for a longer time and vice versa. This increasing order may be applied similarly for the intervals 45, 46, 47, 48. Balancing the recharging between the electrical energy storage units makes it possible to reduce the overall recharging time of the chain 30.

[0081] Between two successive instants, a module can be controlled so that the voltage between its terminals passes successively from Vc to 0 and vice versa during the positive part of the period T2 or -Vc to 0 and vice versa during the negative part. of period 36, for example by pulse width modulation. This helps to reduce harmonic distortions when charging the electrical energy storage unit.

[0082] [Fig.3] represents a circuit 100, intended to be integrated within an electrically powered vehicle, using chains 30 according to [Fig.2a].

[0083] The circuit 100 comprises an input interface 101. This input interface is intended to be connected for example to a charging station for an electrically powered vehicle, capable of supplying a single- or polyphase alternating electric voltage or a direct voltage.

[0084] In the example shown in [Fig.3], the input interface 101 comprises three terminals lOlx, lOly, lOlz, capable of being connected to a respective phase of a three-phase alternating voltage. The interface 101 comprises an additional terminal lOln capable of being connected to the neutral of an alternating voltage. When a vehicle charging station connected to the input interface supplies a direct voltage or a single-phase alternating voltage, an interconnection circuit (not shown) arranged between this charging station and the input interface 101 of the circuit 100 makes it possible to distribute the voltage supplied to the three terminals lOlx, lOly and lOlz.

[0085] The circuit 100 comprises a rotating electrical machine 102. In the example shown in [Fig.3], the electrical machine 102 is a polyphase machine, comprising three phases, denoted 102x, 102y and 102z.

[0086] A control unit 109 is present in the circuit 100. The control unit 109 may be a processor or an integrated circuit, for example an FPGA or an ASIC, comprising the means for implementing the control functions of the circuit 100 and for controlling the set of switches within the circuit 100.

[0087] The circuit 100 as shown comprises a plurality of chains 103 composed of three chains 30. These three chains are according to the chain 30 shown in [Fig.2a] and are composed of a plurality of electrical modules 10 according to [Fig.1a] or 1b. In this example, the chains 30 each comprise four identical modules 10 and according to the module 10 shown in [Fig.1a] or 1b.

[0088] The strings 30 of [Fig.3] can be connected to a respective phase 102x, 102y, 102z of the electrical machine 102 by closing the switches of the plurality of switches 107.

[0089] When the strings 30 are connected to a respective phase 102x, 102y, 102z of the electrical machine 102, the control unit 109 can control the switches of the plurality of strings 103 so that they each supply an alternating voltage to the phases 102x, 102y, 102z of the electrical machine 102. As an example, this supplied voltage can be such as the voltage 35 shown in [Fig.2b], the voltages generated by the strings 30 being able to be phase-shifted by 120 degrees between them.

[0090] When the strings 30 are connected to a respective phase 102x, 102y, 102z of the electrical machine 102, and the electrical machine 102 is generating an alternating voltage, for example during regenerative braking, the control unit 109 can control the switches of the plurality of strings 103 so that the electrical energy storage units of the modules 10 can be recharged from this alternating voltage.

[0091] In the example shown in [Fig.3], the strings 30 can be connected to a respective terminal lOlx, lOly, lOlz of the input interface by closing the switches of the plurality of switches 106. When they are connected to the input interface, the strings are capable of receiving an alternating or direct voltage supplied by a charging terminal connected to the input interface.

[0092] In the example shown in [Fig. 3], the circuit 100 is reversible, that is to say that the control unit can control the switches within the circuit in such a way that the chains provide an alternating voltage to the terminals of the input interface 101. As an example, the chains can generate a voltage such as the voltage 35 shown in Figure 2, the voltages generated by the chains 30 being able to be phase shifted by 120 degrees between them.

[0093] The invention is not limited to what has been described with reference to the figures.

[0094] Only a portion of the modules 10 of the plurality of chains 103 may have a switching cell.

[0095] The switching cell arranged between the primary 11a and secondary 11b terminals of the modules 10 may comprise a switch with an electromechanical system, bidirectional in voltage and current when it is controlled in the closed position.

[0096] The control unit 109 may comprise a main control unit and several subsidiary control units, for example one subsidiary control unit per chain 30, and one subsidiary control unit per module 10, the functions of controlling the circuit and piloting the switches within the circuit being distributed within the main and subsidiary control units.

Claims

Claims

1. Chain (30) of modules (10) for an electrical circuit (100) comprising a first terminal (37a) and a second terminal (37b), each module (10) comprising: - a primary terminal (11a) and a secondary terminal (11b), the primary terminal (11a) being connected to the secondary terminal (11b) of another module (10) and / or the secondary terminal (11b) is connected to the primary terminal (11a) of another module (10) - an electrical energy storage unit (12), and - an H-shaped switching bridge (13), the bridge (13) comprising two switching arms comprising two controllable switches (14a, 14b, 14c, 14d) arranged on either side of a midpoint (13a, 13b), each midpoint (13a, 13b) being connected to one of the terminals (11a, 11b) of the module (10), the electrical energy storage unit (12) being arranged in a branch in parallel with the switching arms, this branch being devoid of switches,Characterized in that all or part of the modules (10) comprise a bidirectional switching cell arranged between their primary terminal (11a) and their secondary terminal (11b), this switching cell comprising at least one controllable semiconductor switch (15, 16a, 16b).

2. Chain (30) according to the preceding claim, each switching cell comprising a bidirectional transistor (15), in particular a four-quadrant GaN-based power transistor.

3. Chain (30) according to claim 1, each switching cell comprising two antiparallel-mounted unidirectional transistors (16a, 16b), in particular MOS field effect transistors or bipolar transistors.

4. A chain (30) according to claim 1, each switching cell comprising a microelectromechanical system switch.

5. Chain (30) according to any preceding claim, the switching cell and the switching bridge (13) of all the modules (10) having switches of the same type.

6. A chain (30) according to any preceding claim, the first and second terminals (37a, 37b) defining the single output voltage of the chain.

7. A chain (30) according to any preceding claim, the electrical energy storage unit (12) having a nominal voltage of between 3 and 60V

8. Electrical circuit (100) for powering a rotating electrical propulsion machine (102) of a vehicle comprising - a polyphase electrical machine (102), - an input interface (101) capable of being connected to a charging station, - a plurality of strings (30) of electrical modules (10), each string (30) being according to any one of the preceding claims, - a system of switches (106, 107) allowing each string (30) to be connected to the terminals of a phase (102x, 102y, 102z) of the electrical machine (102) or to the input interface (101), and - a control unit (109), capable of controlling the switches within the electrical circuit (100).

9. Circuit (100) according to the preceding claim, the control unit (109) being configured to disconnect from the rest of the chain (30) the electrical energy storage unit (12) of a module (10) comprising a switching cell by controlling the at least one switch (15, 16a, 16b) of said cell to be in the closed position.

10. Circuit (100) according to the preceding claim, the control unit (109) being configured to disconnect the electrical energy storage unit (12) from a module (10) by also controlling the switches (14a, 14b, 14c, 14d) of the switching bridge (13) of said module, the switches (14a, 14b, 14c, 14d) connected to the same potential of the energy storage unit (12) being controlled to be in the open position, the others to be in the closed position.

11. Circuit (100) according to any one of claims 8 to 10, the number of chains (30) being greater than or equal to the number of phases (102x, 102y, 102z) of the rotating electrical machine (102).

12. Circuit (100) according to any one of claims 8 to 11, the system of switches (106, 107) allowing for each chain (30) to connect it to the terminals of a phase (102x, 102y, 102z) of the electrical machine (102) to which this chain (30) is dedicated.

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