FR3151718A1 - Power supply system and method for multi-phase electric motor - Google Patents

Abstract

Power supply system and method for multi-phase electric motor Electrical energy supply system (1), comprising at least two power supply lines (3), at least two separate energy sources (B1 to BN) each capable of delivering a direct voltage, and an electronic control unit (9), each energy source (B1 to BN) being connected to each power supply line (3) via a current interrupting device (5A, 5B, 5C) controlled by the electronic control unit (9) so as to electrically couple each power supply line (3) to one of the energy sources (B1 to BN) at a given time. Figure for abstract: Fig.1

Description

Power supply system and method for multi-phase electric motor

The present invention relates to the supply of electrical energy to an appliance from a plurality of electrical energy sources, such as for example the supply of different phases of a multi-phase electric motor of the appliance, in particular those of an electric motor powered by a plurality of batteries.

STATE OF THE ART

The field of batteries powering an electric motor is vast, whether to power single-phase motors or multi-phase motors. Recent advances in batteries now make it possible to power the electric motors of high-power devices (vehicles or tools) (electric vehicles, brush cutters, lawnmowers, etc.). However, this field is reduced when the device can be powered by two or even several batteries that can add their respective powers in parallel to power the same electric motor. The electronic management system (noted by the acronym BMS in English, for "Battery Management System") certainly manages the paralleling of the batteries according to the power requirements of the motor, but we know that paralleling batteries can generate safety problems, particularly when the voltage levels of these batteries are different, when the batteries are of different technologies or when the batteries have different operating histories.

For example, we can cite French patent application FR3078454, which discloses a power supply module for an electric vehicle motor, the motor being of three-phase brushless technology and powered by power supply modules, each power supply module comprising an electric accumulator and a controlled switch bridge coupled in parallel on a power supply bus. The switch bridge, arranged between the motor power supply bus and the accumulator, is a reversible charger and inverter device, the latter mode converting the electrical energy of the accumulator to adjust the voltage of the motor power supply bus. Several power supply modules can be electrically coupled in parallel on the power supply bus. A power supply module can also be continuously powered by another power supply module through the power supply bus to balance its accumulator for example.

When batteries, also called accumulators, are connected in parallel, energy losses are also observed since, in general, in a parallel battery contact architecture, the most charged battery with a higher voltage actually charges the weakest battery with a lower voltage at the same time as it supplies current to power the motor. To avoid too much energy loss other than in the motor power supply, it is therefore prudent in this case to use batteries with similar voltage levels, technologies and a similar state of aging. However, it is not possible to date to envisage paralleling at least two batteries of different technology, voltage or aging to power the same electric motor together without noticing interactions, sources of future safety problems, between the different batteries connected in parallel. It should also be noted that adding inverters to the batteries in order to adapt their output voltage in order to connect them in parallel requires associated electronics that are bulky and expensive.

An object of the present invention is therefore to propose a solution to overcome the drawbacks mentioned above, and in particular, to propose means to improve the safety of a power supply to a multi-phase electric motor from several batteries having different voltage characteristics without there being an electrical connection between batteries during operation of the electric motor. Another objective would be to solve this problem while avoiding the installation of inverters, since these components pose problems in terms of size, weight and price.

Other objects, features and advantages of the present invention will become apparent from the following description and accompanying drawings. It is understood that other advantages may be incorporated.

SUMMARY

To achieve this objective, an electrical energy supply system is proposed comprising at least two supply lines, at least two separate energy sources each capable of delivering a direct voltage, and an electronic control unit, each energy source being connected to each supply line via a current interruption device controlled by the electronic control unit so as to electrically couple each supply line to one of the energy sources at a given time.

Thus, the power supply system is configured in such a way that the electronic control unit controls each current interrupting device at a given time, so that each power supply line is supplied at that time by only one energy source.

This avoids connecting two batteries in parallel on the same power supply line at any time, in particular to avoid unwanted interactions between the batteries (unnecessary energy losses, safety, etc.). Such a system is particularly suitable for powering a multi-phase electric motor of a tool, for example a portable one, with batteries that may have different characteristics, such as different nominal voltages, different technologies, different operating histories, etc.

According to another aspect, a tool is provided comprising the system as defined above.

• une fourniture d’un système comprenant :

• au moins deux lignes d’alimentation ;
• au moins deux sources d’énergie distinctes aptes à délivrer, chacune, une tension continue ; et
• une unité de commande électronique ;
• chaque source d’énergie étant reliée à chaque ligne d’alimentation par l’intermédiaire d’un dispositif d’interruption de courant piloté par l’unité de commande électronique de façon à coupler électriquement à un instant donné chaque ligne d’alimentation à l’une des sources d’énergie.

• Ainsi, l’unité de commande électronique peut piloter les dispositifs d’interruption de courant de sorte que, pour chaque instant, les dispositifs d’interruption de courant couplent électriquement une ligne d’alimentation avec seulement l’une des sources d’énergie.

According to another aspect, there is provided a method of supplying electrical energy, comprising:

• a supply of a system comprising:

• at least two supply lines;
• at least two separate energy sources each capable of delivering a direct voltage; and
• an electronic control unit;
• each energy source being connected to each power supply line via a current interruption device controlled by the electronic control unit so as to electrically couple each power supply line to one of the energy sources at a given time.

• Thus, the electronic control unit can control the current interrupting devices so that, for each instant, the current interrupting devices electrically couple a supply line with only one of the energy sources.

BRIEF DESCRIPTION OF THE FIGURES

The aims, objects, as well as the features and advantages of the invention will become more apparent from the detailed description of one embodiment thereof which is illustrated by the following accompanying drawings in which:

There schematically represents a view of an embodiment of a power supply system with three power lines and N energy sources, N being an integer such that N ≥ 2, for independently powering each phase of a three-phase motor;

There schematically represents a view of an embodiment of a power supply system with two power lines and N energy sources, N being an integer such that N >2, for independently supplying each phase or group of phases of a three-phase motor;

There represents another embodiment of the current interrupting devices of a battery for the supply of a three-phase electric motor;

There schematically represents a view of the curves of the average currents supplied by two batteries of a three-line power supply system;

there schematically represents a view of the operating state curves of the current interruption devices of a two-battery power system.

The drawings are given as examples and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate the understanding of the invention and are not necessarily to the scale of practical applications.

DETAILED DESCRIPTION

Before beginning a detailed review of embodiments and implementations of the invention, optional features are set out below which may optionally be used in combination or alternatively.

For example, the electronic control unit is configured to control the current interrupting devices cyclically and preferably at low frequency.

For example, at least one current interrupting device is a controlled electronic switch.

For example, at least one current interrupting device includes two simultaneously driven transistors, each transistor having a first input terminal, a second output terminal, and a control terminal connecting the input terminal to the output terminal, the two driven transistors being coupled in series such that the input terminal of one is electrically coupled to the input terminal of the other.

According to one example, the tool is a portable tool, that is, it is intended to be carried by a user during its use. This is the case for an electric pruning shears, a leaf blower, a chainsaw, a brush cutter, etc. The tool may also be movable manually by the user, that is, it is intended to be moved on the ground by the user during its use. This is the case, for example, for a lawn mower or a stump grinder.

For example, it is an agricultural or wine-growing tool.

In one example, the tool includes a controller capable of issuing a power command for a multi-phase electric motor, wherein the electronic control unit of the system is configured to receive a power command issued by the controller, and to control the current interruption devices based on the received power command.

According to one example, the electronic control unit of the system includes controlling the phases of the electric motor based on information from the control unit, voltage and/or current information from each motor phase half-bridge and takes this information into account to control the current interruption devices.

The control member is for example actuated by a user. It may comprise a button, a handle or a trigger to activate the control mode.

It is specified that in the context of the present invention, the expression "A electrically coupled to B" or "A coupled to B" or "A connected to B" is synonymous with "A is in electrical connection with B" and does not necessarily mean that there is no member between A and B. Thus these expressions are understood to mean an electrical connection between two elements, this connection may or may not be direct, this means that it is possible that between a first device A and a second device B which are electrically connected, a current flows in A, in B, and on the path connecting A to B, this path may or may not include other electrical equipment.

Conversely, in the context of the present invention, the term "electrically directly connected" means a direct electrical connection between two elements. This means that between a first device A and a second device B which are electrically directly connected no other equipment is present, other than an electrical connection or several electrical connections.

In Figures 1 and 2, a power supply system 1 is schematically shown for supplying at its terminals 3A, 3B, 3C power supply lines 3 of a multi-phase electric motor 10, that is to say a motor comprising several phases 12, each phase 12 of the motor 10 being supplied for the operation of the motor 10. In the example of Figures 1 and 2, this is a three-phase permanent magnet motor, each of the three phases 12 of which is coupled to a power supply line 3 at the terminals 3A, 3B, 3C of the power supply system 1. The motor 10 may be a three-phase brushed or brushless motor 10 of a device (vehicle, tool), not shown for the sake of simplification. The rotor of the motor 10 is not shown here for the sake of simplification. This device, however comprising active members 20 actuated by its motor 10 and associated with a control member 22 such as a trigger for example to generate signals necessary for controlling the motor 10, is for example an agricultural or wine-growing tool such as electric pruning shears, an agricultural brush cutter, a lawn mower, a leaf blower, a chainsaw, .... According to one example, the tool is portable. Generally, the motor 10 comprises at least two phases 12, for example three phases 12, as illustrated in FIGS. 1 and 2. Each phase 12 of the motor 10 can be coupled to a power supply line 3, preferably separate (this is the case of the ), with two separate supply lines (case of the ), one of the power supply lines 3 then connecting two phases 12 of the three-phase motor 10, and in any case by at least two power supply lines 3 for a multi-phase motor 10 comprising more than two phases 12. Each phase 12 is coupled to a power supply line 3 in particular by means of a half-bridge 14 voltage converter to control, by means of an electronic control card 19, the current supply in each of the phases 12. Generally, the electronic control card 19 is configured to control the motor 10 according to the signals emitted by the control member 22, and in particular, to control the motor 10 in PWM mode (or “Pulse width modulation” in English, i.e. in pulse width modulation). The control frequency of each half-bridge 14 is chosen at a high value, for example 20 kHz so as to make the operation of the control of the motor 10 inaudible. Other lower or higher frequencies are also possible of course and easily achievable by the person skilled in the art who knows however that the losses in the half-bridges 14 are increasing functions of the frequency and therefore that a compromise is necessary between the losses by Joule effect in the half-bridges 14 and the noise generated for the operation of the motor 10.

The system 1 also comprises at least two separate energy sources B1, B2, …, BN (N being an integer and corresponding to the number of energy sources) and for each energy source B1, B2, …, BN, comprises at least one current interrupting device 5A, 5B, 5C per supply line 3 at terminals 3A, 3B, 3C of the system. Separate energy sources B1, B2, …, BN are understood to mean sources whose characteristics such as their output voltage, their state of charge, their technology, their operating history, etc. may be different.

Figures 1 and 2 being produced schematically, the supply lines 3 connecting the different current interrupting devices 5A, 5B, 5C to the phase 12 of the corresponding motor 10 via the terminals 3A, 3B, 3C of the system 1 are shown in solid lines for the current interrupting devices 5A (figures 1 and 2), in dotted lines for the current interrupting devices 5B of the and in dashed line for 5C current interrupting devices of the or 5B of the .

An energy source B1, B2, …, BN is configured to deliver a continuous current and voltage. An energy source B1, B2, …, BN may be a battery and each of the batteries may comprise an assembly of several electrochemical elements in series or in parallel giving it different nominal voltage, capacity and therefore power characteristics. For example, the system 1 comprises N batteries B1, B2, …, BN as illustrated in FIGS. 1 and 2. Each battery B1, B2, …, BN comprises two poles 2, 4 having opposite polarities (i.e. positive and negative). A first pole 2 is intended to be electrically coupled to the ground 7 of the tool, and the second pole 4 is electrically coupled to an input terminal of a current interrupting device 5A, 5B, 5C.

Each battery B1, B2, …, BN is connected to a number of current interrupting devices corresponding to the number of power supply lines 3 of the system 1, for example three switches 5A, 5B and 5C connecting three terminals 3A, 3B and 3C connecting the power supply lines 3 of a system 1 to three power supply lines 3 (case of the ) ; 2 switches 5A and 5B connecting two terminals 3A and 3B for connecting the power supply lines 3 of a system 1 to two power supply lines 3 (case of the ). In the case of a system 1 with three power supply lines 3, each current interrupting device 5A, 5B, 5C, electrically coupled to one of the batteries B1, B2, …, BN is configured to electrically couple this battery to the connection terminal 3A, 3B, 3C when closing one of the current interrupting devices 5A, 5B, 5C associated with said terminal. Thus, at most 3 batteries can supply the 3 power supply lines 3 to the terminals 3A, 3B, 3C without these three batteries being coupled together to one of these terminals. A single battery can also be coupled to the three supply lines 3, the three current interrupting devices 5A, 5B, 5C of this battery B1, …, BN then all being in the closed position while all the other current interrupting devices 5A, 5B, 5C of the other batteries B1, …, BN remain in the open state.

For example, as illustrated in the , three power supply lines 3 of the electric motor 10 are each electrically coupled to the connection terminals 3A, 3B, 3C of the power supply system 1. The system 1 comprises N energy sources B1 to BN, each of which is connected to the input of three current interrupting devices 5A, 5B, 5C, the output of each of these three current interrupting devices 5A, 5B, 5C being electrically coupled to the power supply lines 3 via the respective connection terminals 3A, 3B, 3C of the power supply system 1. Furthermore, the power supply system 1 comprises an electronic control unit 9 for controlling the current interrupting devices 5A, 5B, 5C so that at a given moment, each connection terminal 3A, 3B, 3C is supplied by only one of the batteries B1 to BN by closing of one of the current interrupting devices 5A, 5B, 5C associated with it. Thus, to supply the 3 power supply lines 3 simultaneously at a given time, it is then necessary that among all the current interrupting devices 5A, 5B, 5C of the different banks B1 to BN, there is only one closed 5A device to connect the connection terminal 3A, only one closed 5B device to connect the connection terminal 3B and only one closed 5C device to connect the connection terminal 3C; all the other current interrupting devices being in the open state.

According to another example illustrated in the , two power supply lines 3 of the electric motor 10 are each electrically coupled to the connection terminals 3A, 3B of the power supply system 1. The electric motor 10 having three phases 12, they can then only be supplied on two power supply lines 3. Thus, a first power supply line 3 is coupled to a first phase 12 of the motor 10, and a second power supply line 3 is coupled to the second and third phases 12 of the motor 10. Furthermore, the power supply system 1 comprises N energy sources B1 to BN, each of them being connected to the input of two current interrupting devices 5A, 5B, the output of each of these two current interrupting devices 5A, 5B being electrically coupled to the power supply lines 3 via the respective connection terminals 3A, 3B of the power supply system 1. Thus, in order to supply at a given moment the two power supply lines 3 simultaneously, it is then necessary that among all the current interruption devices 5A, 5B of the different batteries B1 to BN, there is only one device 5A closed to connect the connection terminal 3A and only one device 5B closed to connect the connection terminal 3B; all the other current interruption devices being in the open state.

A current interrupting device 5A, 5B, 5C may be an electronic switch controlled by the electronic control unit 9. A current interrupting device 5A, 5B, 5C may be in the form of a controlled electronic or electromechanical component of the relay type, IGBT (for Low Voltage General Switch), bipolar transistor, controlled transistor of the MOSFET type (abbreviation of “metal-oxide-semiconductor field-effect transistor” according to the acronym in English) … Preferably, as illustrated schematically in the , a current interrupting device 5A, 5B, 5C may comprise two MOSFET transistors coupled in series and in reverse, each being controlled. Control of the current interrupting device (of type 5A, 5B, 5C) is then understood to mean the simultaneous control of the two MOSFETs. Each MOSFET has a first terminal called Source and a second terminal called Drain. By reverse coupled, it is understood that the source of one is connected in series to the source of the other or that the Drain of one is connected in series to the Drain of the other, this latter configuration being that shown in the . Indeed, a MOSFET transistor has a controlled interruption effect of the current but includes a diode effect in parallel, these two effects being modeled in the . In fact, to prevent current from flowing in the opposite direction to the battery when the switches of the two MOSFETs of a current interruption device are open, it is necessary to block the current flow by a reverse diode effect of the second MOSFET connected in series.

In particular, the electronic control unit 9 is configured so as to control each current interrupting device 5A, 5B, 5C of each battery B1, B2, …, BN independently of each other, such that, for each instant, the open or closed state of each current interrupting device 5A, 5B, 5C makes it possible to electrically couple a power line 3 to only one of the energy sources B1, B2, …, BN. For each instant, all the power lines 3 are coupled to one of the energy sources B1, …, BN but not all the energy sources B1, B2, …, BN are necessarily electrically coupled to the power lines 3, and two distinct energy sources B1, B2, …, BN cannot supply the same power line 3 at the same instant.

Thus, the power supply of a tool comprising a multi-phase motor 10 can be managed using several batteries B1, …, BN each delivering, if necessary, a current to power the tool without however being connected in parallel. This therefore avoids the system 1 suffering the risks and disadvantages of managing batteries B1, …, BN connected directly in parallel.

Advantageously, the system 1 may comprise batteries B1, B2, …, BN not necessarily having the same characteristics of nominal voltage, technology, state of charge, or even which do not have the same aging or usage history. Indeed, batteries B1, …, BN having characteristics, as mentioned above, different cannot therefore in principle be connected together, whether in series or in parallel, to power a tool.

According to another advantage, the system 1 is suitable for combining the powers of batteries B1, B2, …, BN, in order to be able to increase the autonomy, the power, or even both of a tool, without however making it necessary to purchase or use batteries B1, …, BN specifically adapted for this purpose (for example in this case two batteries of the same nominal voltage, of the same technology, of the same state of charge and of the same operating history can be electrically coupled in parallel without excessive risk).

Thus, in the context of the direct power supply of each phase 12 of the three-phase motor 10, the input voltages of each half-bridge 14 at a given moment can be different on each of the power supply lines 3 when they are not powered by the same battery B1, B2, ... BN.

More particularly, if, between two successive times t and t+1, a first battery B1 coupled to one of the terminals 3A, 3B, 3C of a power supply line 3 at time t is disconnected to connect at the following time t+1 to this same terminal 3A, 3B, 3C a second battery B2, it is possible that the power supply voltage of this power supply line 3 varies significantly if the voltages of the two batteries B1, B2 are distinct. In order to limit the voltage variations due to the connection and disconnection of the batteries B1, B2, each phase 12 of the motor 10 coupled to a power supply line 3 may comprise, in addition to a half-bridge 14, a capacitor 16 for managing the significant voltage variations. Thus, the capacitors 16 make it possible to regulate the voltage of the half-bridges 14. Advantageously, each capacitor 16 makes it possible to limit the minimum and maximum voltage ranges authorized for correct operation of the motor 10.

Furthermore, each supply line 3 may comprise a measuring device 18 for measuring the voltage applied to the supply line 3. The measuring devices 18 are coupled to the electronic control card 19 of the motor 10, by connections not shown for the sake of simplification. Thus, the electronic control card 19 is configured to measure the different voltages of the power supply lines 3 of the motor 10 so as to control each half-bridge 14 by adapting the current or voltage characteristics in order to operate the motor 10. The characteristics necessary for the operation of the motor 10 are controlled by means of the control member 22 linked to the operation of the active members 20 actuated by the motor 10. Preferably, the electronic control card 19 of the motor 10 can be coupled to the electronic control unit 9 of the power supply system 1, in order to communicate in particular information such as the voltage values of the power supply lines 3 or the operating power setpoints of the motor 10, so as to quickly select the battery or batteries B1 to BN capable of supplying energy on each power supply line 3 of the motor 10. The term electronic control card 19 is understood to mean a separate electronic card or a part of an electronic card and which can for example constitute a part of the electronic control unit 9 of the system 1. In the example described, the system 1 powers a multi-phase motor 10 driven by its electronic control card 19 and communications are necessary with the control unit 9 to ensure proper power supply to the motor 10. These communications are illustrated by the dotted arrows in FIGS. 1 and 2. These may be wired and/or wireless communications. Preferably, the electronic control card 19 is positioned as close as possible to the control unit 9 and therefore in the power supply system 1. Generally, an appliance such as a vehicle or a tool that would require such a power supply system 1 may include an electronic card 19 for controlling the appliance, to control the motor 10 or another device of the appliance, and in the case of the need for such an electronic card 19, it may be located in or outside the power supply system 1.

In general, the motor 10 can be powered by different batteries B1, B2, … BN, each battery B1, …, BN having its own characteristics, possibly different from the other batteries B1, …, BN without having the disadvantage of managing risks and complexity of a direct connection of batteries B1, …, BN in parallel. It will be noted that when at least two batteries B1, B2, …, BN providing two distinct DC voltages are electrically coupled to the phases 12 of the motor 10, it is the voltage of the lowest power supply line 3 which will limit the power of the tool. Thus, the electronic control unit 9 can be configured to manage the connection of the batteries B1, B2, …, BN according to the useful power for the tool, expressed for example by a trigger of the tool, by a force generated by the tool or by communication with the electronic control card 19. The electronic control unit 9 is configured to interpret the power supply orders from the tool so as to control, for each battery B1 to BN, the current interruption devices 5A, 5B, 5C in order to ensure the power supply of the tool. The control of the current interruption devices 5A, 5B, 5C is preferably carried out at low frequency, for example of the order of 1 Hz so as to avoid on the one hand generating noises audible to the user and on the other hand to avoid operating the batteries B1 to BN in a pulsed mode at high frequency which can be detrimental to their service life.

On the , an example of curve 30 of the total average current I supplied to the motor 10 by the system 1 as a function of time T from two batteries B1 and B2 has been shown. This total average current is the sum of the average currents supplied by the two batteries B1 and B2. A first curve 31 represents the average current supplied to the motor 10 by the first battery B1, and a second curve 32 represents the average current supplied to the motor 10 by a second battery B2. The two batteries B1 and B2 are of identical technologies and nominal voltages but their state of charge is different (for example, 80% for B1 and 20% for B2). They can in fact each provide a maximum total average current having the value Imax, the two batteries B1 and B2 thus being able to provide a total average current equal to 2*Imax. The battery B2 here having a much lower state of charge than the battery B1 will in fact be much less stressed. System 1 can thus provide an average current which can be equal to the sum of the average currents provided by each battery B1, B2 while distributing over time the connections to the tool of each battery B1, B2 according to their residual energy.

System 1 allows the energy from each of the batteries B1, B2 to be managed and directed at a given moment to activate the power supply to each power supply line 3.

Advantageously, the electronic control unit 9 is configured to identify the number of batteries B1, B2, …, BN connected at a given time; to recover parameters from each battery B1, …, BN and/or to take into account parameters recorded by the user before the system 1 is put into service. Preferably, the electronic control unit 9 is configured to communicate with each battery B1, B2 connected so as to identify their main characteristics, for example the maximum current, the minimum voltage in operation, their state of charge, …. These communications between the electronic control unit 9 and each battery B1, B2 are illustrated by the dotted arrows in FIGS. 1 and 2. These main characteristics can be stored in the battery B1, B2, can be calculated by the battery B1, B2, can be entered manually by a user or be provided by an additional monitoring system (not shown) connected to each battery B1, B2 and communicating with the electronic control unit 9.

The electronic control unit 9 is also configured to communicate with the electronic control card 19 to assess the power requirements to be provided for the proper operation of the engine 10.

A method of supplying electrical energy, in particular for a multi-phase motor 10, can be implemented by the system as defined above. The method comprises the main steps of supplying the system 1 and controlling, by the electronic control unit 9 of the system 1, the current interrupting devices 5A, 5B, 5C so that, for each instant, the current interrupting devices 5A, 5B, 5C electrically couple a power supply line 3 with only one of the energy sources B1 to BN.

An example of the control of the current interruption devices 5A, 5B, 5C of each battery B1 and B2 to obtain the average current curves 30, 31 and 32 of the is illustrated in . In this figure, six curves 40 to 45 are shown representing, as a function of time T, the operating state of six current interrupting devices 5A, 5B, 5C shown in coupled to batteries B1 and B2. In particular, the first three curves 40 to 42 represent the operating state of the three current interrupting devices 5A, 5B, 5C coupled to a first battery B1, and respectively denoted B1-5A, B1-5B and B1-5C. Furthermore, the other three curves 43 to 45 represent the operating state of the three current interrupting devices 5A, 5B, 5C coupled to a second battery B2, and respectively denoted B2-5A, B2-5B and B2-5C. Furthermore, on each of the curves 40 to 45, the time T is represented on the abscissa and the operating state B1-5A, B1-5B, B1-5C, B2-5A, B2-5B and B2-5C of the current interrupting device 5A, 5B, 5C on the ordinate. Generally, each current interrupting device 5A, 5B, 5C occupies either an open state (and the associated curves 40 to 45 have a value of 0 on the ordinate), or a closed state (and the associated curves 40 to 45 have a value of 1 on the ordinate). Thus, it can be noted that the current interrupting device B1-5A is always closed over time, the current interrupting device B2-5A is always open, thus, the current interrupting devices B1-5A and B2-5A allow a phase 12 of the motor 10 to be supplied only by the first battery B1. It will also be noted on the , that when the current interrupting device B1-5B is closed, then the current interrupting device B2-5B is open. It is also noted that when the current interrupting device B1-5C is closed, then the current interrupting device B2-5C is open. Thus, at any instant, each phase 12 of the motor 10 is coupled to only one battery B1 or B2 of the system 1.

Claims (10)

Electrical power supply system (1), comprising:

• at least two supply lines (3);
• at least two separate energy sources (B1 to BN) each capable of delivering a direct voltage; and
• an electronic control unit (9);

characterized in that each energy source (B1 to BN) is connected to each power supply line (3) via a current interruption device (5A, 5B, 5C) controlled by the electronic control unit (9) so as to electrically couple each power supply line (3) at a given moment to one of the energy sources (B1 to BN). System according to the preceding claim, wherein the electronic control unit (9) is configured to control the current interruption devices (5A, 5B, 5C) cyclically, preferably at low frequency. System according to any one of the preceding claims, in which at least one current interrupting device (5A, 5B, 5C) is a controlled electronic switch. A system according to any preceding claim, wherein at least one current interrupting device (5A, 5B, 5C) comprises two simultaneously controlled transistors, each transistor having a first input terminal, a second output terminal and a control terminal connecting the input terminal to the output terminal, the two controlled transistors being coupled in series such that the input terminal of one is electrically coupled to the input terminal of the other. A tool comprising a feed system according to any preceding claim. Tool according to the preceding claim, comprising a control member (22) capable of issuing a power command for a multi-phase electric motor, in which the electronic control unit (9) of the system (1) is configured to receive a power command issued by the control member (22), and to control the current interruption devices (5A, 5B, 5C) as a function of the received power command. Tool according to any one of the preceding claims, the tool being an agricultural or viticultural tool. Tool according to the preceding claim, taken from: pruning shears, an agricultural brush cutter, a lawn mower, a leaf blower, a chainsaw, a stump grinder. A tool according to any preceding claim, the tool being a portable tool or one which can be moved manually by the user during use. Method for supplying electrical energy, comprising:
- a supply of a system comprising:

• at least two supply lines (3);
• at least two separate energy sources (B1 to BN) each capable of delivering a direct voltage; and
• an electronic control unit (9);

characterized in that each energy source (B1 to BN) is connected to each power supply line (3) via a current interruption device (5A, 5B, 5C) controlled by the electronic control unit (9) so as to electrically couple each power supply line (3) at a given moment to one of the energy sources (B1 to BN)
.