Power management methods and systems for an electric machine

Abstract

The invention relates to a power control system for an electric machine, the system comprising a management interface (9) configured so as to manage power exchanged between an electrical device and an electric machine (2), the management interface (9) comprising four switch devices (10 to 13) forming a bridge circuit (P), and a capacitive device (Ca) electrically coupled between terminals (BP1, BP2) of the bridge circuit (P); each switch device being controlled and configured so as to operate as a voltage-unidirectional and current-bidirectional switch, and an electronic control unit (20) configured so as to control the four switch devices in such a way as to discharge the capacitive device (Ca) and to control closure of each of the four switch devices when a voltage across the terminals (BP1, BP2) of the bridge circuit (P) is strictly lower than a voltage threshold, in order to keep the capacitive device (Ca) discharged.

Description

[0001] Power control processes and systems for an electrical machine

[0002] TECHNICAL FIELD OF THE INVENTION

[0003] The present invention relates to the power control of electrical machines, such as electric motors and generators, in particular the power management of polyphase electric machines with variable speeds, and more particularly the power management of variable speed motorization systems equipped with a polyphase electric motor.

[0004] STATE OF THE ART

[0005] Currently, there are different methods for managing the power supplied or consumed by electrical machines.

[0006] One can cite, for example, the publication: “Applying MERS for Induction Motor Driving, Miao-miao Cheng, Takanori Isobe, Shuhei Kato, Kazuhiko Fukutani, Hideo Sumitani, and Ryuichi Shimada Journal of the Japan Institute of Power Electronics JIPE-37- 12 Vol. 37 (2012.3), pages 139 to 145”, which discloses a use of a MERS type device (corresponding to the acronym for “Magnetic Energy Recovery Switch” in English) to manage the operation of an electric motor.We can also cite the publication: “Control and Design Principle of SVC-MERS—a New Reactive Power Compensator with Line Frequency Switching and Small Capacitor, Daisuke Shiojima, Miao-miao Cheng, Takanori Isobe, and Ryuichi Shimada; Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology; Tokyo, Japan 152-8550; in IEEE (2012) 978-1-4673-0803-8 / 12,” ​​which also discloses the use of a MERS-type device to manage the operation of an electrical generator. This publication describes a method for obtaining sinusoidal currents of different shapes to achieve different variations in the generator's reactive power output.

[0007] We can also cite the publication: “Feasible Series Compensation Applications using Magnetic Energy Recovery Switch (MERS), Jan A. Wiik, Takanori Isobe, Taku Takaku, F Danang Wijaya, Kazuhiro Usuki, Nobuyuki Arai and Ryuichi Shimada; Tokyo Institute of Technology N1-33, 2-12-1 O-okayama, Meguro-ku, Tokyo, Japan; Fuji Electric Device Technology Co., Ltd, 4-18-1, Tsukama, Matsumoto, Japan”, which discloses a use of MERS-type devices as a series compensator in high-power transmission systems where the power flow can be controlled and increased.

[0008] However, the methods proposed in these publications are not sufficiently robust and do not provide sufficient safety, particularly when controlling an electrical machine to increase or decrease the power exchanged with an electrical energy source or electrical device.

[0009] SUMMARY OF THE INVENTION

[0010] One object of the present invention is therefore to overcome the disadvantages mentioned above, and more particularly to provide simple and robust means for managing the electrical power supplied or consumed by an electrical machine.

[0011] Another objective is to provide means to ensure safety, particularly electrical safety, during power change commands intended for electrical machines.

[0012] According to one aspect of the invention, a power control method for an electrical machine is proposed, comprising:

[0013] - the provision of a management interface, the management interface comprising a first terminal configured to be electrically coupled to an electrical device taken from an electrical power source or an electrical appliance, and a second terminal configured to be electrically coupled to an electrical machine, the management interface being configured to manage power exchanged between the electrical device and the electrical machine, the management interface comprising four switching devices forming a bridge circuit, the bridge circuit having first and second terminals coupled respectively to the first and second terminals of the management interface, the management interface also comprising a capacitive device electrically coupled between the third and fourth terminals of the bridge circuit; each switching device being controlled and configured to operate as a unidirectional voltage switch and a bidirectional current switch, and

[0014] - a first control step configured to control the four switching devices in order to discharge the capacitive device.

[0015] Advantageously, the method includes a second control stage configured to command a closure of each of the four switching devices when a voltage between the third and fourth terminals of the bridge circuit is strictly less than a voltage threshold, in order to keep the capacitive device discharged.

[0016] Alternatively or in combination, said first control step comprises an alternation between a first command and a second command when a current flowing between the first terminal of the management interface and the second terminal of the management interface changes sign, the first command comprising a first closing of the first two switching devices arranged along a first diagonal of the bridge circuit, carried out simultaneously with a first opening of the other two switching devices arranged along a second diagonal of the bridge circuit, the second command comprising a second closing of the other two switching devices arranged along the second diagonal of the bridge circuit, carried out simultaneously with a second opening of the switching devices arranged along the first diagonal,The first command is executed to discharge the capacitive device when the electric current flows in the first direction between the first terminal of the management interface and the second terminal of the management interface, and the second command is executed to discharge the capacitive device when the electric current flows in the opposite direction to the first direction between the first terminal of the management interface and the second terminal of the management interface.

[0017] Thus, this method ensures that the capacitive device remains discharged for safety reasons, particularly to prevent overheating of the electrical machine or to prevent exceeding its operating limits. Furthermore, during the second control stage, the bridge circuit's switching devices are not periodically switched, which avoids excessive system power consumption and limits Joule heating losses in the control interface. Another advantage is that during the second control stage, the switching devices are simply controlled by a single closing command. Therefore, it is not necessary to periodically alternate the switching devices, which would involve complex control of the switching devices. Advantageously, precision is not required during the second control stage.The method according to the invention makes it possible to keep the capacitive device discharged without the risk of an unexpected restart, for example, due to incorrect switching of the switching devices that could cause the capacitive device to recharge. Thus, the bypass of the capacitive device of the control interface is guaranteed in the event of a malfunction of the switching devices of the control interface or an incorrect control of these devices, while keeping the electrical machine running.

[0018] According to another aspect of the invention, a power control method for an electrical machine is proposed, comprising:

[0019] - the provision of a management interface, the management interface comprising a first terminal configured to be electrically coupled to an electrical device taken from an electrical power source or an electrical appliance, and a second terminal configured to be electrically coupled to an electrical machine, the management interface being configured to manage power exchanged between the electrical device and the electrical machine, the management interface comprising four switching devices forming a bridge circuit, the bridge circuit having first and second terminals coupled respectively to the first and second terminals of the management interface, the management interface also comprising a capacitive device electrically coupled between the third and fourth terminals of the bridge circuit; each switching device being controlled and configured to operate as a unidirectional voltage and bidirectional current switch, and

[0020] - a first control step configured to control the four switching devices in order to discharge the capacitive device.

[0021] Advantageously, the control interface includes an additional electrically coupled switching device between the third and fourth terminals of the bridge circuit, and the method includes a second control stage configured to command a closure of the additional switching device when a voltage between the third and fourth terminals of the bridge circuit is strictly less than a voltage threshold, in order to keep the capacitive device discharged.

[0022] Alternatively or in combination, said first control step comprises an alternation between a first command and a second command when a current flowing between the first terminal of the management interface and the second terminal of the management interface changes sign, the first command comprising a first closing of the first two switching devices arranged along a first diagonal of the bridge circuit, carried out simultaneously with a first opening of the other two switching devices arranged along a second diagonal of the bridge circuit, the second command comprising a second closing of the other two switching devices arranged along the second diagonal of the bridge circuit, carried out simultaneously with a second opening of the switching devices arranged along the first diagonal,The first command is executed to discharge the capacitive device when the electric current flows in the first direction between the first terminal of the management interface and the second terminal of the management interface, and the second command is executed to discharge the capacitive device when the electric current flows in the opposite direction to the first direction between the first terminal of the management interface and the second terminal of the management interface.

[0023] In another respect, a power control system for an electrical machine is proposed, comprising:

[0024] - a management interface comprising a first terminal configured to be electrically coupled to an electrical device taken from an electrical power source or an electrical appliance, and a second terminal configured to be electrically coupled to an electrical machine, the management interface being configured to manage power exchanged between the electrical device and the electrical machine, the management interface comprising four switching devices forming a bridge circuit, the bridge circuit having first and second terminals coupled respectively to the first and second terminals of the management interface, the management interface also comprising a capacitive device electrically coupled between the third and fourth terminals of the bridge circuit, each switching device being controlled and configured to operate as a unidirectional voltage switch and a bidirectional current switch, and

[0025] - an electronic control unit configured to control the four switching devices in order to discharge the capacitive device.

[0026] Advantageously, the electronic control unit is configured to command a closure of each of the four switching devices when a voltage between the third and fourth terminals of the bridge circuit is strictly less than a voltage threshold, in order to keep the capacitive device discharged.

[0027] Alternatively or in combination, the electronic control unit is configured to control the four switching devices alternately between a first command and a second command when a current flowing between the first terminal of the management interface and the second terminal of the management interface changes sign, the first command comprising a first closing of the first two switching devices arranged along a first diagonal of the bridge circuit, carried out simultaneously with a first opening of the other two switching devices arranged along a second diagonal of the bridge circuit, the second command comprising a second closing of the other two switching devices arranged along the second diagonal of the bridge circuit, carried out simultaneously with a second opening of the switching devices arranged along the first diagonal,The first command is executed to discharge the capacitive device when the electric current flows in the first direction between the first terminal of the management interface and the second terminal of the management interface, and the second command is executed to discharge the capacitive device when the electric current flows in the opposite direction to the first direction between the first terminal of the management interface and the second terminal of the management interface.

[0028] In another respect, a power control system for an electrical machine is proposed, comprising:

[0029] - a management interface comprising a first terminal configured to be electrically coupled to an electrical device taken from an electrical power source or an electrical appliance, and a second terminal configured to be electrically coupled to an electrical machine, the management interface being configured to manage power exchanged between the electrical device and the electrical machine, the management interface comprising four switching devices forming a bridge circuit, the bridge circuit having first and second terminals coupled respectively to the first and second terminals of the management interface, the management interface also comprising a capacitive device electrically coupled between the third and fourth terminals of the bridge circuit, each switching device being controlled and configured to operate as a unidirectional voltage and bidirectional current switch,and - an electronic control unit configured to control the four switching devices in such a way as to discharge the capacitive device.

[0030] Advantageously, the management interface includes an additional electrically coupled switch device between the third and fourth terminals of the bridge circuit, the electronic control unit being configured to command a closure of the additional switch device when a voltage between the third and fourth terminals of the bridge circuit is strictly less than a voltage threshold, in order to keep the capacitive device discharged.

[0031] Alternatively or in combination, the electronic control unit is configured to control the four switching devices alternately between a first command and a second command when a current flowing between the first terminal of the management interface and the second terminal of the management interface changes sign, the first command comprising a first closing of the first two switching devices arranged along a first diagonal of the bridge circuit, carried out simultaneously with a first opening of the other two switching devices arranged along a second diagonal of the bridge circuit, the second command comprising a second closing of the other two switching devices arranged along the second diagonal of the bridge circuit, carried out simultaneously with a second opening of the switching devices arranged along the first diagonal,The first command is executed to discharge the capacitive device when the electric current flows in the first direction between the first terminal of the management interface and the second terminal of the management interface, and the second command is executed to discharge the capacitive device when the electric current flows in the opposite direction to the first direction between the first terminal of the management interface and the second terminal of the management interface.

[0032] BRIEF DESCRIPTION OF THE FIGURES

[0033] The other objects, features and advantages of the present invention will become apparent from the following description and accompanying drawings in which: Figure 1 represents one embodiment of a power control system for an electrical machine; Figure 2 represents another embodiment of a power control system for an electrical machine; Figures 3 to 5 represent the main steps of an implementation method of power control for an electrical machine; and Figures 6 and 7 represent other embodiments of a power control system for an electrical machine.

[0034] The drawings are given as examples and are not limiting to the invention. They constitute schematic representations of principle intended to facilitate understanding of the invention and are not necessarily to scale with practical applications.

[0035] DETAILED DESCRIPTION OF THE INVENTION

[0036] Before beginning a detailed review of embodiments and implementations of the invention, optional features that may be used in combination or alternatively are stated below.

[0037] According to one example, the management interface includes an additional electrically coupled switch device between the first and second terminals of the management interface, and in that the second control stage is further configured to command a closure of the additional switch device when the voltage between the third and fourth terminals of the bridge circuit is strictly below the voltage threshold.

[0038] According to one example, the process includes, after the second control step, a third control step configured to control the opening of the additional switching device, and then to control the four switching devices of the bridge circuit in such a way as to manage the power exchanged between the electrical device and the electrical machine.

[0039] According to one example, the process includes, after the second control step, a third control step configured to control the four switching devices in order to manage the power exchanged between the electrical device and the electrical machine.

[0040] According to one example, the process includes measuring the voltage between the third and fourth terminals of the bridge circuit, and when the voltage is greater than or equal to a voltage threshold, the first control step is carried out, followed by the second control step.

[0041] According to another example, the process includes a measurement of at least one temperature, said at least one temperature being taken from a temperature of the electrical machine and a temperature of the management interface, and when said at least one temperature is greater than or equal to a temperature threshold, the first control step is carried out, and then the second control step.

[0042] According to another example, an electromechanical conversion chain is proposed, comprising an electrical machine, an electrical device taken from an electrical energy source or an electrical appliance, and a power control system as defined above.

[0043] It is specified that within the framework of the present invention, the expressions "A coupled to B", "A electrically coupled to B", "A connected to B" or "A electrically connected to B" are synonymous with "A is in electrical connection with B" and do not necessarily mean that there is no component between A and B. Thus, these expressions refer to an electrical connection between two elements, this connection being either direct or indirect; this means that it is possible that between a first device A and a second device B which are electrically connected, linked or coupled, a current may flow in A, in B, and along the path connecting A to B, this path being either or not including other electrical equipment.

[0044] Conversely, in the context of the present invention, the term "electrically connected directly" or "directly connected" refers to a direct electrical connection between two elements. This means that between a first device A and a second device B that are electrically connected directly, no other equipment is present, other than an electrical connection or several electrical connections.

[0045] It is specified that in the context of the present invention, the term "electrically placed" or "electrically located" means the positioning of a device on a line in which a current flows.

[0046] It is specified that within the framework of the present invention, the term "A electrically coupled between B and C" means a positioning of a device A on a line connecting B to C in which a current flows between A, B and C. The device A can be electrically coupled to B and C, either in series or in parallel.

[0047] Figures 1, 2, 6 and 7 show different embodiments of a power control system 1 for an electrical machine 2. Figures 3 to 7 show the main steps of different implementation methods of a power control process for an electrical machine 2.

[0048] Furthermore, in figures 1 and 2, an electromechanical conversion chain 100 is represented, comprising an electrical machine 2, an electrical device 3, and the power control system 1.

[0049] In general, the electric machine 2 is configured to convert electrical energy into mechanical energy (when the electric machine operates in motor mode) or mechanical energy into electrical energy (when the electric machine operates in generator mode). The electric machine 2 comprises a stator with several windings and a rotor that may or may not be separately excited and driven, for example, a permanent magnet or wound-rotor synchronous machine, a squirrel-cage or wound-rotor induction machine, or a synchronous-reluctance or variable-reluctance machine.

[0050] When electrical machine 2 operates in motor mode, it consumes current and voltage to provide mechanical torque. When electrical machine 2 operates in generator mode, it supplies electrical current and voltage to electrical device 3. Preferably, electrical machine 2 is polyphase, meaning it has N phases (where N is an integer). For example, as shown in Figure 2, N is equal to 3. In this case, electrical machine 2 is three-phase, meaning it has three phases A, B, and C.

[0051] Furthermore, the electrical device 3 can be an electrical energy source 4 (and the electrical device 3 can supply energy to the machine 2 in motor mode, or possibly receive energy from the machine 2 in generator mode) or an electrical appliance 400 (i.e., an electrical energy-consuming appliance). The source 4 can be a current source or a voltage source. The source can also be an electrical power distribution network to supply alternating voltage and current. For example, the source 4 is a battery, to store and / or supply electrical energy, in particular from a direct current voltage (Vdc).

[0052] Preferably, the electromechanical conversion chain 100 comprises a power converter 5 electrically coupled to the electrical device 3. The power converter 5 with the electrical device 3 form a set 30, also noted as electrical system 30.

[0053] In general, the power converter 5 is configured to exchange alternating voltage and current with the electrical machine 2. If the electrical device 3 is an electrical power source 4, the power converter 5 can be configured to convert the direct current voltage and current supplied by the source 4 into alternating voltage and current for the electrical machine 2 (in motor mode). For example, the power converter 5 is variable frequency. For example, the power converter 5 could be an inverter or a variable frequency drive. If the electrical device 3 is an electrical appliance 400, the power converter 5 is configured to convert the alternating voltage and current supplied by the electrical machine 2 (in generator mode) into either direct or alternating voltage and current for the electrical appliance 400.For example, the power converter 5 can be a diode rectifier or a controlled rectifier. Generally, the power converter 5 is electrically coupled to the electrical device 3 by an electrical connection having M phases (where M is an integer). M can be equal to 2, in the case of direct current, or equal to 3 for alternating current.

[0054] For example, as illustrated in Figure 2, the electrical device 3 is a source 4 of direct current (DC) power. The converter 5 includes, for each phase A, B, C, of ​​the electrical machine 2, a group of two switches 6, 7 electrically connected in series. For each phase A, B, C, the two switches 6, 7 in the group are connected in parallel with the source 4. Each group of two switches 6, 7 supplies an alternating voltage and current to an output terminal of the converter G1 to G3 associated with the group. The output terminal G1 to G3 of the converter 5 associated with a group is connected between the two switches in the group. Furthermore, the converter 5 includes, for each of the switches 6, 7 in each group, a diode 8 connected in parallel across the terminals of the switch 6, 7.

[0055] More specifically, the power control system 1 includes a management interface 9 and an electronic control unit 20.

[0056] In general, the management interface 9 is configured to manage power exchanged between the electrical device 3 and the electrical machine 2. The management interface 9 is electrically coupled between the electrical device 3 and the electrical machine 2. Preferably, the management interface 9 is coupled between the power converter 5 and the electrical machine 2, as illustrated in Figures 1 and 2. Preferably, the management interface 9 is electrically coupled in series between the power converter 5 and the electrical machine 2, as illustrated in Figure 2.

[0057] The management interface 9 includes at least one first terminal BE1 to BE3 configured to be electrically connected to the electrical device 3, and at least one second terminal BS1 to BS3 configured to be electrically connected to the electrical machine 2. More specifically, the management interface 9 includes, for each phase

[0058] A, B, C, of ​​the electrical machine 2, a second terminal BS1 to BS3 coupled to phase A,

[0059] B, C. In addition, the management interface 9 includes, for each group of switches of the power converter 5, a first terminal BE1 to BE3 coupled to an output terminal G1 to G3 of the converter 5.

[0060] Furthermore, for each phase A, B, C of machine 2, interface 9 comprises a group GA, GB, GC of switching devices 10 to 13. Each group GA, GB, GC of switching devices 10 to 13 is associated with a phase A, B, C of machine 2. In addition, each group GA, GB, GC of interface 9 comprises four switching devices 10 to 13 forming a P-bridge circuit. The four switching devices 10 to 13 in each group GA, GB, GC are also said to be bridged. In the example shown in Figure 2, the control interface comprises three P-bridge circuits. Each P-bridge circuit has a first terminal e1 to e3 and a second terminal s1 to s3. The first terminal e1 to e3 of a P-bridge circuit is coupled, preferably directly, to a first terminal BE1 to BE3 of the management interface 9. The second terminal s1 to s3 of a P-bridge circuit is coupled, preferably directly, to a second terminal BS1 to BS3 of the management interface 9.

[0061] In addition, the management interface 9 also includes, for each P-bridge circuit, an associated electrically coupled capacitive device Ca, preferably directly, between the third and fourth terminals BP1, BP2 of the P-bridge circuit. A capacitive device Ca is also said to be associated with a group GA, GB, GC of switching devices 10 to 13. For example, a capacitive device Ca can be a capacitor, a battery, a supercapacitor, or a combination of several of these aforementioned elements.

[0062] In general, each 10-to-13 switching device is controlled and configured to operate as a unidirectional voltage switch and a bidirectional current switch. For example, a 10-to-13 controlled switch can be an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal Oxide Semiconductor Field Effect Transistor).

[0063] In addition, the electronic control unit 20 is configured to control the closing and opening of the four switch devices 10 to 13 of each of the groups GA, GB, GC of the management interface 9. Preferably, each switch device 10 to 13 includes a control terminal coupled to the electronic control unit 20, via connections C1, so that the electronic control unit 20 can control the closed and open state (i.e. respectively passing and blocking) of the switch devices 10 to 13.

[0064] Advantageously, each group GA, GB, GC of the control interface 9 includes a diode 14 connected in parallel with the input and output terminals of each switch device 10 to 13 in the group GA, GB, GC. Such a diode 14 ensures the bidirectionality of the alternating current flowing within each assembly, denoted the diode / switch assembly, formed by a switch device 10 to 13 and an associated diode 14 connected in parallel with the switch device 10 to 13. A diode 14 ensures the spontaneous closure of the diode / switch assembly when the current becomes zero. Thus, the two diodes 14 of a first leg comprising the switch devices 10, 11 coupled to the first terminal e1 of the P-bridge circuit, become conducting when the voltage across them becomes zero (i.e., across the third and fourth terminals BP1, BP2 of the P-bridge circuit) in order to ensure current continuity.Thus, when a switching device 10 to 13 is in a blocking state, meaning that no current flows through it, the associated diode 14 conducts in only one direction, or positive or negative sign, of the current. Conversely, when a switching device 10 to 13 is in a conducting state, it allows current to flow through it in the opposite direction. Diode 14 ensures current flow in at least one direction, particularly when its associated switching device malfunctions. In other words, diodes 14 prevent the capacitive devices Ca from recharging (after being discharged) before the next current half-cycle, that is, when the alternating current changes direction.

[0065] In general, the power exchanged between the electrical device 3 and the electrical machine 2 has a real component, called active power, and an imaginary component, called reactive power. Thus, the control interface 9 is designed to supply a portion of the reactive power to the electrical machine 2, whether the machine is in motor or generator mode. More specifically, the portion of reactive power supplied to the electrical machine 2 depends on the amount of energy stored in the capacitive devices Ca of the control interface 9. In other words, the portion of reactive power supplied by the control interface 9 depends on the state of charge of the capacitive devices Ca of the control interface 9.

[0066] In general, when the electrical machine 2 is in working order, an alternating current I flows between the electrical device 3 and the electrical machine 2, via the management interface 9.

[0067] Furthermore, the power control system 1 is said to be in normal operating mode when the control interface 9 is functioning, that is, when the capacitive devices Ca charge and discharge during power exchanges between the electrical device 3 and the electrical machine 2. For example, the control interface 9 can supply reactive power to the machine 2 to increase its magnetic flux, thereby increasing its performance. In particular, when the magnetic flux of the electrical machine 2 increases, the torque increases. In cases where this increase is not controlled, the magnetic flux can exceed the recommended operating conditions and may lead to overheating.It is therefore advantageous to be able to activate or deactivate the reactive power supply via the management interface 9, for example, in the event of a fault or generally to manage the power of machine 2. Activation and deactivation can be performed without interrupting the operation of electrical machine 2. For the sake of simplicity, we will subsequently refer to activating the reactive power supply via the management interface 9 as activating interface 9, and deactivating the reactive power supply via the management interface 9 as deactivating interface 9. Whether or not the reactive power supplied to machine 2 increases, the power control system 1 remains in normal operating mode and machine 2 continues to function.

[0068] In general, disabling interface 9 includes a first command step Cd1 or a second command step Cd1 and advantageously first and second command steps Cd1, Cd2.

[0069] The first control step Cd1 is configured to control, via the electronic control unit 20, for at least one P-bridge circuit, and preferably for each P-bridge circuit, the four switching devices 10 to 13 of the P-bridge circuit so as to discharge the capacitive device Ca associated with the P-bridge circuit. For example, the first control step may include a first closing of the first two switching devices 10, 13 arranged along a first diagonal of the P-bridge circuit, alternating with a second closing of the other two switching devices 11, 12 arranged along the second diagonal of the P-bridge circuit. In addition, the first closing is carried out simultaneously with a first opening of the switching devices 11, 12 of the second diagonal.The simultaneous occurrence of the first closing and opening is illustrated in Figure 3 and is denoted as the first command. The second closing occurs simultaneously with a second opening of the switching devices 10 and 13 on the first diagonal. The simultaneous occurrence of the second closing and opening is denoted as the second command.

[0070] Note that to discharge the capacitive device Ca associated with the P-bridge circuit, the first command is executed when, for example, the current flows in one direction, for example, when the current I is negative, and the second command is executed when the current I is positive (i.e., the current flows in a second direction opposite to the first), that is, when the current I changes sign. Figures 3, 4, 6, and 7 show the positive current I flowing in the second direction.

[0071] Conversely, to load the capacitive device Ca associated with the P-bridge circuit, the first command is executed when the current I is positive, and the second command is executed when the current I is negative, that is, when the current I changes sign. In other words, the first control step Cd1 involves alternating control of the diagonals of the P-bridge circuit. Specifically, the alternation between the first and second diagonal commands occurs when the alternating current I changes sign, that is, when the current I passes through zero. Furthermore, the alternation is performed periodically according to the frequency of the alternating current.

[0072] The second control step Cd2, if applicable, is configured to command, via the electronic control unit 20, the closing of each of the four switching devices 10 to 13 of at least one P-bridge circuit, as illustrated in Figure 4. Furthermore, this closing occurs when the voltage Vc between the third and fourth terminals BP1, BP2 of the P-bridge circuit is strictly less than a voltage threshold Veps, in order to keep the capacitive device Ca discharged. Preferably, for each P-bridge circuit, the closing of each of the four switching devices 10 to 13 of the P-bridge circuit is commanded when the voltage Vc between the third and fourth terminals BP1, BP2 of the P-bridge circuit is strictly less than a voltage threshold Veps, in order to keep the capacitive device Ca associated with the P-bridge circuit discharged.Closing a switch device 10 to 13 in the management interface 9 results in the forced (i.e., sustained) conduction of the switch device 10 to 13. The second control step Cd2 allows the switch devices 10 to 13 to be controlled differently from the first control step Cd1. In other words, when the voltage Vc is strictly less than a voltage threshold Veps, the first control step Cd1 is stopped, and then the second control step Cd2 is executed.

[0073] Thus, it is guaranteed that each capacitive device Ca has a minimum, or even zero, stored energy. Furthermore, this implementation minimizes Joule effect losses in the conversion chain 100. Indeed, when all the switching devices 10 to 13 of a P-bridge circuit are closed, each switching device 10 to 13 carries a current equal to I / 2, where I corresponds to the current present at the first and second terminals e1, s1 of the P-bridge circuit. The following relationships are then obtained:

[0074] Req = 2 x (Rint / 2) = Rint, with:

[0075] - Req: the equivalent resistance of the P-bridge circuit (expressed in Ohms); and

[0076] - Rint: the resistance of a 10 to 13 switching device (expressed in Ohms).

[0077] In other words, the Joule effect losses of the management interface 9 correspond to the Joule effect losses of a switching device 10 to 13 of a P-bridge circuit.

[0078] Figure 5 shows the main steps of an implementation method for a power control system for an electrical machine 2. The method can be implemented using the power control system 1 as defined above. The method may include an initial control step CdO in which the switching devices 10 to 13 of the control interface 9 are activated so that the machine 2 is in its normal operating state. Then, when it is desired to deactivate the interface 9, the first control step Cd1 is performed to discharge the capacitive device(s) Ca. The second control step Cd2 can then be performed to ensure that the capacitive devices Ca remain discharged. Preferably, the first control step Cd1 is stopped, and then the second control step Cd2 is performed.

[0079] Advantageously, the method includes measuring the voltage Vc between the third and fourth terminals BP1, BP2 of the P-bridge circuit, and when the voltage is greater than or equal to a voltage threshold, the first control step Cd1 is executed, and then the second control step Cd2 can be executed. This prevents exceeding the maximum operating voltage supported by the electrical machine 2.

[0080] The process may further include measuring at least one temperature, said at least one temperature being chosen from the temperature of the electrical machine 2 and a temperature of the control interface 9. When the measured temperature is greater than or equal to a temperature threshold, the first control step Cd1 is executed, and then the second control step Cd2 can be executed. This prevents the control system 1 from overheating.

[0081] Furthermore, the process may include a third control step Cd3, called the reconnection step. The activation of interface 9 is also said to include the third control step Cd3. During this reconnection step Cd3, the deactivation of interface 9 is stopped by controlling the switching devices 10 to 13 of the P-bridge circuits so as to return to the normal operating state, that is, to the initial control step CdO.

[0082] For example, after the second control step Cd2, a third control step Cd3 is performed, configured to control, for each group of switching devices GA, GB, GC, the four switching devices 10 to 13 in order to manage the power exchanged between the electrical device 3 and the electrical machine 2. For example, during the third control step Cd3, for each group of switching devices GA, GB, GC, the four switching devices 10 to 13 can be controlled to load the capacitive devices Ca associated respectively with the groups GA, GB, GC. In particular, when it is necessary to reactivate interface 9, the reconnection step is performed when the alternating current I passes through zero. In the case where the electrical machine 2 has three phases A, B, C, the three phases are reconnected successively as the current flowing in a phase A, B, C passes through zero.

[0083] The reconnection step Cd3 can be performed in different ways. One possibility is to restart from the second control step Cd2 by performing a reverse process. This reverse process involves repeating the first control step Cd1, which triggers the discharge of the capacitive devices Ca, and then returning to the initial control step CdO. This allows for a gradual restart of the system and avoids abrupt changes in the behavior of the electrical machine 2. A second possibility is to return directly to the initial control step CdO after stopping the second control step Cd2.

[0084] According to another embodiment, illustrated in Figure 6, the control interface 9 includes at least one additional switch device intBP, denoted internal switch, for example, a set of internal additional switches. Preferably, the control interface 9 includes, for each P-bridge circuit, an additional switch device intBP, electrically coupled between the third and fourth terminals BP1, BP2 of the P-bridge circuit. In this case, when the first control step Cd1 is executed, the internal switch intBP is controlled by the electronic control unit 20 to be in the open state.The second control step Cd2 is configured to command, via the electronic control unit 20, the closure of the additional switch device intBP when the voltage Vc between the third and fourth terminals BP1, BP2 of the P-bridge circuit is strictly below the voltage threshold Veps, in order to keep the capacitive device Ca discharged. According to one implementation, the first control step Cd1 is maintained while the second control step Cd2 is executed. In other words, the alternating control of the diagonals of the P-bridge circuits is maintained in discharge mode to prevent any unintentional recharging of the associated capacitive devices Ca. Thus, the activation of interface 9 to return to normal operating mode can be facilitated simply by re-engaging the internal switches intBP and then stopping the first control step Cd1.It can be noted that this embodiment generates more Joule losses in the control interface 9, since the equivalent resistance Req is equal to 2 x Rint + RintBP, where RintBP corresponds to the resistance of the additional switching device (expressed in Ohms). Figure 7 shows another embodiment in which the control interface 9 includes at least one additional switching device extBP, called an external switch, for example, a set of external additional switches, electrically coupled between the first and second terminals BE1, BS1 of the control interface 9. In this case, when the first control step Cd1 is executed, the external switch intBP is controlled by the electronic control unit 20 to be in the open state.In addition, the second control step Cd2 is configured to command a closure of the external switch extBP when the voltage Vc between the third and fourth terminals BP1, BP2 of the P-bridge circuit is strictly less than the voltage threshold Veps.

[0085] In embodiments where system 1 includes an external switch extBP or at least one internal switch intBP, the third control step Cd3 is configured to open each additional switch device intBP, extBP to return to the initial control step CdO. Generally, the third control step Cd3 is configured to control the four switch devices 10 to 13 to manage the power exchanged between the electrical device 3 and the electrical machine 2. For example, the third control step Cd3 is configured to control the four switch devices 10 to 13 of each P-bridge circuit to load each associated capacitive device Ca.

[0086] The electronic control unit 20 is further configured to control the closing and opening of the internal switches intBP and the external switch extBP.

[0087] The internal switches intBP and the external switch extBP can be controlled switches of the IGBT or MOSFET type.

[0088] Thus, thanks to the process just described, we can manage the usage phases of the management interface 9 and minimize energy consumption during the deactivation phases of interface 9. We can therefore avoid penalizing the efficiency of the conversion chain when deactivating interface 9.

[0089] Advantageously, interface 9 can be disabled for the following reasons:

[0090] - stop the increase in torque and return to an initial operating mode;

[0091] - limit thermal heating of the electrical machine 2 caused by the increase in the magnetic flux of the electrical machine 2;

[0092] - when a voltage or current threshold is exceeded at the first terminal BE1 of the management interface 9, to prevent damage to the electrical machine. This reconnection management minimizes any sudden voltage or current variations when the management interface 9 is reconnected.

[0093] We provide a process with improved reliability. We also provide redundancy in the bypass system to enhance safety. This allows reactive power management to be easily activated or deactivated as needed.

Claims

DEMANDS 1. A method for power control for an electrical machine, comprising: • a supply of a management interface (9), the management interface (9) comprising a first terminal (BE1) configured to be electrically coupled to an electrical device (3) taken from an electrical power source (4) or an electrical appliance (400), and a second terminal (BS1) configured to be electrically coupled to an electrical machine (2), the management interface (9) being configured to manage power exchanged between the electrical device (3) and the electrical machine (2), the management interface (9) comprising four switching devices (10 to 13) forming a bridge circuit (P), the bridge circuit (P) having first and second terminals (e1, s1) coupled respectively to the first and second terminals (BE1, BS1) of the management interface (9), the management interface (9) also comprising a capacitive device (Ca) electrically coupled between third and fourth terminals (BP1, BP2) of the bridge circuit (P);each switching device (10 to 13) being controlled and configured to operate as a unidirectional voltage and bidirectional current switch, and; • a first control step (Cd1) configured to control the four switching devices (10 to 13) so as to discharge the capacitive device (Ca), characterized in that the method comprises a second control step (Cd2) configured to control a closure of each of the four switching devices (10 to 13) when a voltage (Vc) between the third and fourth terminals (BP1, BP2) of the bridge circuit (P) is strictly less than a voltage threshold (Veps), in order to keep the capacitive device (Ca) discharged;and in that said first command step (Cd1) comprises an alternation between a first command and a second command when a current flowing between the first terminal (BE1) of the management interface (9) and the second terminal (BE2) of the management interface (9) changes sign, the first command comprising a first closing of two first switching devices (10, 13) arranged along a first diagonal of the bridge circuit (P), carried out simultaneously with a first opening of the; two other switching devices (11, 12) arranged along a second diagonal of the bridge circuit (P), the second command comprising a second closing of the two other switching devices (11, 12) arranged along the second diagonal of the bridge circuit (P), carried out simultaneously with a second opening of the switching devices (10, 13) arranged along the first diagonal, the first command being carried out to discharge the capacitive device (Ca) when the electric current flows in a first direction between the first terminal (BE1) of the management interface (9) and the second terminal (BE2) of the management interface (9) and the second command being carried out to discharge the capacitive device (Ca) when the electric current flows in a second direction, opposite to the first direction, between the first terminal (BE1) of the management interface (9) and the second terminal (BE2) of the management interface (9).

2. A method for power control for an electrical machine, comprising: • a supply of a management interface (9), the management interface (9) comprising a first terminal (BE1) configured to be electrically coupled to an electrical device (3) taken from an electrical power source (4) or an electrical appliance (400), and a second terminal (BS1) configured to be electrically coupled to an electrical machine (2), the management interface (9) being configured to manage power exchanged between the electrical device (3) and the electrical machine (2), the management interface (9) comprising four switching devices (10 to 13) forming a bridge circuit (P), the bridge circuit (P) having first and second terminals (e1, s1) coupled respectively to the first and second terminals (BE1, BS1) of the management interface (9), the management interface (9) also comprising a capacitive device (Ca) electrically coupled between third and fourth terminals (BP1, BP2) of the bridge circuit (P);each switching device (10 to 13) being controlled and configured to operate as a unidirectional voltage and bidirectional current switch, and; • a first control step (Cd1) configured to control the four switching devices (10 to 13) in order to discharge the capacitive device (Ca), characterized in that the management interface (9) includes an additional switching device (intBP) electrically coupled between the third and fourth terminals (BP1, BP2) of the circuit in bridge (P), and in that the method includes a second control step (Cd2) configured to command a closure of the additional switching device (intBP) when a voltage (Vc) between the third and fourth terminals (BP1, BP2) of the bridge circuit (P) is strictly less than a voltage threshold (Veps), in order to keep the capacitive device (Ca) discharged; and in that said first control step (Cd1) includes an alternation between a first command and a second command when a current flowing between the first terminal (BE1) of the management interface (9) and the second terminal (BE2) of the management interface (9) changes sign, the first command comprising a first closure of the first two switching devices (10, 13) arranged along a first diagonal of the bridge circuit (P), carried out simultaneously with a first opening of the other two switching devices (11,12) arranged along a second diagonal of the bridge circuit (P), the second command comprising a second closing of the two other switching devices (11, 12) arranged along the second diagonal of the bridge circuit (P), carried out simultaneously with a second opening of the switching devices (10, 13) arranged along the first diagonal, the first command being carried out to discharge the capacitive device (Ca) when the electric current flows in a first direction between the first terminal (BE1) of the management interface (9) and the second terminal (BE2) of the management interface (9) and the second command being carried out to discharge the capacitive device (Ca) when the electric current flows in a second direction, opposite to the first direction, between the first terminal (BE1) of the management interface (9) and the second terminal (BE2) of the management interface (9).

3. Method according to claim 1, wherein the control interface (9) comprises an additional switching device (extBP) electrically coupled between the first and second terminals (BE1, BS1) of the control interface (9), and wherein the second control stage (Cd2) is further configured to command a closure of the additional switching device (extBP) when the voltage (Vc) between the third and fourth terminals (BP1, BP2) of the bridge circuit (P) is strictly less than the voltage threshold (Veps).

4. A method according to any one of claims 2 to 3, comprising, after the second control step (Cd2), a third control step (Cd3) configured to control the opening of the additional switch device (intBP, extBP), and then to control the four switch devices (10 to 13) of the bridge circuit (P) so as to manage the power exchanged between the electrical device (3) and the electrical machine (2).

5. Method according to claim 1, comprising, after the second control step (Cd2), a third control step (Cd3) configured to control the four switching devices (10 to 13) in such a way as to manage the power exchanged between the electrical device (3) and the electrical machine (2).

6. Method according to any one of claims 1 to 5, comprising a measurement of the voltage (Vc) between the third and fourth terminals (BP1, BP2) of the bridge circuit (P), and when the voltage (Vc) is greater than or equal to a voltage threshold, the first control step (Cd1) is carried out, then the second control step (Cd2).

7. A method according to any one of claims 1 to 6, comprising a measurement of at least one temperature, said at least one temperature being taken from a temperature of the electrical machine (2) and a temperature of the control interface (9), and when said at least one temperature is greater than or equal to a temperature threshold, the first control step (Cd1) is carried out, followed by the second control step (Cd2).

8. Power control system for an electrical machine, comprising: • a management interface (9) comprising a first terminal (BE1) configured to be electrically coupled to an electrical device (3) taken from an electrical power source (4) or an electrical appliance (400), and a second terminal (BS1) configured to be electrically coupled to an electrical machine (2), the management interface (9) being configured to manage power exchanged between the electrical device (3) and the electrical machine (2), the management interface (9) comprising four switching devices (10 to 13) forming a bridge circuit (P), the bridge circuit (P) having first and second terminals (e1, s1) coupled respectively to the first and second terminals (BE1, BS1) of the management interface (9), the management interface (9) also comprising a capacitive device (Ca) electrically coupled between third and fourth terminals (BP1, BP2) of the bridge circuit (P),each switching device (10 to 13) being controlled and configured to operate as a unidirectional voltage switch and a bidirectional current switch, and, • an electronic control unit (20) configured to control the four switching devices (10 to 13) so as to discharge the capacitive device (Ca), characterized in that The electronic control unit (20) is configured to command the closure of each of the four switching devices (10 to 13) when a voltage (Vc) between the third and fourth terminals (BP1, BP2) of the bridge circuit (P) is strictly less than a voltage threshold (Veps), in order to keep the capacitive device (Ca) discharged; and in that the electronic control unit (20) is configured to command the four switching devices (10 to 13) alternately between a first command and a second command when a current flowing between the first terminal (BE1) of the management interface (9) and the second terminal (BE2) of the management interface (9) changes sign, the first command comprising a first closure of the first two switching devices (10, 13) arranged along a first diagonal of the bridge circuit (P), carried out simultaneously with a first opening of the other two switching devices (11,12) arranged along a second diagonal of the bridge circuit (P), the second command comprising a second closing of the two other switching devices (11, 12) arranged along the second diagonal of the bridge circuit (P), carried out simultaneously with a second opening of the switching devices (10, 13) arranged along the first diagonal, the first command being carried out to discharge the capacitive device (Ca) when the electric current flows in a first direction between the first terminal (BE1) of the management interface (9) and the second terminal (BE2) of the management interface (9) and the second command being carried out to discharge the capacitive device (Ca) when the electric current flows in a second direction, opposite to the first direction, between the first terminal (BE1) of the management interface (9) and the second terminal (BE2) of the management interface (9).

9. Power control system for an electrical machine, comprising: • a management interface (9) comprising a first terminal (BE1) configured to be electrically coupled to an electrical device (3) taken from an electrical power source (4) or an electrical appliance (400), and a second terminal (BS1) configured to be electrically coupled to an electrical machine (2), the management interface (9) being configured to manage power exchanged between the electrical device (3) and the electrical machine (2), the management interface (9) comprising four switching devices (10 to 13) forming a bridge circuit (P), the bridge circuit (P) having first and second terminals (e1, s1) coupled respectively to the first and second terminals (BE1, BS1) of the management interface (9), the management interface (9) also comprising a capacitive device (Ca) electrically coupled between the third and fourth terminals (BP1, BP2) of the bridge circuit (P); each switching device (10 to 13) being controlled and configured to operate as a unidirectional voltage and bidirectional current switch, and • an electronic control unit (20) configured to control the four switching devices (10 to 13) so as to discharge the capacitive device (Ca), characterized in that the management interface (9) includes an additional switching device (intBP) electrically coupled between the third and fourth terminals (BP1, BP2) of the bridge circuit (P), the electronic control unit (20) being configured to control a closure of the additional switching device (intBP) when a voltage (Vc) between the third and fourth terminals (BP1, BP2) of the bridge circuit (P) is strictly less than a voltage threshold (Veps),in order to keep the capacitive device (Ca) discharged; and in that the electronic control unit (20) is configured to control the four switching devices (10 to 13) alternately between a first command and a second command when a current flowing between the first terminal (BE1) of the management interface (9) and the second terminal (BE2) of the management interface (9) changes sign, the first command comprising a first closing of the first two switching devices (10, 13) arranged along a first diagonal of the bridge circuit (P), carried out simultaneously with a first opening of the other two switching devices (11, 12) arranged along a second diagonal of the bridge circuit (P), the second command comprising a second closing of the other two switching devices (11, 12) arranged along the second diagonal of the bridge circuit (P),carried out simultaneously with a second opening of the switching devices (10, 13) arranged along the first diagonal, the first command being executed to discharge the capacitive device (Ca) when the electric current flows in a first direction between the first terminal (BE1) of the management interface (9) and the second terminal (BE2) of the management interface (9) and the second command being executed to discharge the capacitive device (Ca) when the electric current flows in a second direction, opposite to the first direction, between the first terminal (BE1) of the management interface (9) and the second terminal (BE2) of the management interface (9).

10. Electromechanical conversion chain, comprising an electrical machine (2), an electrical device (3) taken from an electrical power source (4) or an electrical apparatus (400), and a power control system according to any one of claims 8 to 9.

Images