Drive system and associated method

Abstract

The invention relates to a driving system and an associated method. A drive system (1) is proposed comprising a connection circuit and N drive units (2, 3), each drive unit comprising an electric machine (12, 13), a primary power converter (8, 9) configured to supply power to the electric machine. The drive system further comprises:-an auxiliary power converter (18) connected to each of the motors of the drive units by a connection circuit, and-an auxiliary control circuit (100) configured to control the auxiliary power converter and configured to: o connect the auxiliary power converter (18) to the motor of the drive unit of the N drive units by the connection circuit, the drive unit is a target drive unit, o drives the electric machine from the auxiliary power converter (18), o disconnects the primary power converter of the target drive unit from the associated electric machine of the target drive unit.

Description

Technical Field

[0001] The present invention relates to a drive system.

[0002] The present invention more particularly relates to a drive system including a plurality of power converters and electric machines, each of which is powered by a power converter, and a method for operating such a drive system. Background Art

[0003] Generally, a drive system includes at least one power converter and a motor powered by the power converter.

[0004] Electric motors drive systems in factories.

[0005] When a fault is detected, which may be, for example, a ground fault or a short circuit in the power converter, the drive system stops.

[0006] The motor stops driving the system, resulting in a loss of production.

[0007] Furthermore, when the power converter needs to be stopped for maintenance operations, the motor is stopped, so that the motor stops driving the system, resulting in production losses.

[0008] It is therefore proposed to overcome this disadvantage in whole or in part. Summary of the invention

[0009] In view of the foregoing, the present invention proposes a drive system comprising a connection circuit and N drive units, each drive unit comprising a motor and a primary power converter configured to supply power to the motor, N being a non-zero integer.

[0010] The drive system also includes:

[0011] an auxiliary power converter connected to each of the electric machines of the drive unit via a connecting circuit, and

[0012] an auxiliary control circuit configured to control the auxiliary power converter and configured to:

[0013] o connecting the auxiliary power converter to a motor of a drive unit among the N drive units, the drive unit being a target drive unit, through a connecting circuit,

[0014] o driving the motor from an auxiliary power converter,

[0015] o Disconnecting the primary power converter of the target drive unit from the associated electric machine of the target drive unit.

[0016] The auxiliary power converter replaces the primary power converter of the target drive unit so that the motor of the target drive unit is still operable. Since the auxiliary control circuit controls the connection circuit and the auxiliary power converter, the replacement of the primary power converter of the target drive unit by the auxiliary power converter is fast enough to limit the motor speed drop of the motor of the failed drive unit and limit the impact on the system.

[0017] Preferably, the auxiliary control circuit is also configured to detect a fault in one of the N drive units, the target drive unit being the faulty drive unit, and when the fault is a ground fault or a short circuit, the auxiliary power converter is also configured to control the motor to be operational before connecting the auxiliary power converter to the motor if the motor of the faulty drive unit is operational.

[0018] Advantageously, the drive system further comprises a global control circuit, and wherein each drive unit further comprises a local control circuit, the local control circuit being configured to monitor the drive unit and control a primary power converter of the drive unit, the local control circuit of the target drive unit being configured to supply the first power to the motor of the target drive unit, the global control circuit being configured to:

[0019] - controlling the local control circuit and the auxiliary control circuit of the target drive unit so that the sum of the power supplied by the primary power converter of the target drive unit and the power supplied by the auxiliary power converter is equal to the first power, the power supplied by the primary power converter of the target drive unit decreases over time, and the power supplied by the auxiliary power converter increases over time, and

[0020] When the power supplied by the primary power converter of the target drive unit is zero and the power supplied by the auxiliary power converter is equal to the first power, controlling the auxiliary control circuit to disconnect the primary power converter of the target drive unit from the associated electric machine.

[0021] Preferably:

[0022] - each drive unit comprises a first switch connecting the primary power converter of said drive unit to the electric machine of said drive unit, and

[0023] - The connection circuit includes a primary switch and a first switch module, the first switch module is configured to connect the motor of each drive unit to the primary switch, and the auxiliary control circuit is configured to open the first switch of the target drive unit when the primary power converter is disconnected from the associated motor of the target drive unit.

[0024] Advantages:

[0025] the electric motor of the target drive unit comprises a wound rotor comprising windings powered by a power supply module of the target drive unit, and

[0026] The auxiliary control circuit is configured to control a power supply module of the target drive unit so that when the primary power converter of the target drive unit is disconnected, the power supply module stops supplying power to the windings of the wound rotor of the electric machine of the target drive unit.

[0027] Preferably, the connection circuit includes a second switching module powered by a secondary power converter, and the auxiliary control circuit is configured to control the second switching module, the secondary power converter and a power supply module of the target drive unit, so that when the auxiliary power converter is connected, the power supply module supplies power to the winding of the rotor of the target drive unit from the current delivered by the secondary power converter.

[0028] Another object of the invention relates to a method for controlling a drive system comprising a connection circuit and N drive units, each drive unit comprising a motor and a primary power converter for powering the motor, N being a non-zero integer.

[0029] The method includes:

[0030] -(a) connecting the auxiliary power converter to a motor of a drive unit among the N drive units through a connecting circuit, the drive unit being a target drive unit,

[0031] - (b) supplying power to the electric machine from an auxiliary power converter, and

[0032] - (c) disconnecting the primary power converter from the associated electric machine of the target drive unit.

[0033] Preferably, the method comprises:

[0034] - detecting a failure of one of the drive units before processing steps (a), (b), (c), the target drive unit being the failed drive unit,

[0035] - When a faulty drive unit is detected, processing step (c),

[0036] - processing step (a) when the primary power converter of the faulty drive unit is disconnected from the motor of the faulty drive unit, and

[0037] - Supply power from the auxiliary power converter to the motor of the faulty drive unit.

[0038] Advantageously, the method further comprises controlling a motor of the faulty drive unit when the fault is a ground fault or a short circuit and connecting the auxiliary power converter to the motor if the motor is operable.

[0039] Preferably, disconnecting the primary power converter of the target drive unit comprises stopping the power converter.

[0040] Preferably, the primary power converter of the target drive unit supplies the first power to the motor of the target drive unit, and the method comprises:

[0041] - supplying power to the motor from the auxiliary power converter includes controlling the primary power converter and the auxiliary power converter of the target drive unit so that the sum of the power supplied by the primary power converter of the target drive unit and the power supplied by the auxiliary power converter is equal to a first power, the power supplied by the primary power converter of the target drive unit decreases over time, and the power supplied by the auxiliary power converter increases over time, and

[0042] - disconnecting the primary power converter of the target drive unit from the associated electric machine when the power supplied by the primary power converter of the target drive unit is zero and the power supplied by the auxiliary power converter is equal to the first power.

[0043] Advantages:

[0044] - each drive unit comprises a first switch connecting the primary power converter to the motor of said drive unit, and

[0045] a connecting circuit comprising a primary switch and a first switching module, the first switching module connecting the motor of each drive unit to the primary switch,

[0046] - the first switch of each drive unit is closed, the primary switch is opened, and the first switch module is configured so that any current flows through the first switch module,

[0047] -Disconnecting the primary power converter of the target drive unit comprises:

[0048] - Turn on the first switch of the target drive unit.

[0049] Advantageously, connecting the auxiliary power converter comprises:

[0050] - activating the auxiliary power converter to deliver AC voltage,

[0051] - synchronizing the AC voltage delivered by the auxiliary power converter with the AC voltage supplied to the electric motor of the target drive unit,

[0052] - close the primary switch, and

[0053] - Controlling the first switch module to connect the motor of the target drive unit to the closed primary switch.

[0054] Preferably, the connection circuit includes a second switching module powered by a secondary power converter, and connecting the auxiliary power converter includes controlling the second switching module, the secondary power converter and the power supply module of the target drive unit, so that the power supply module supplies power to the winding of the rotor of the target drive unit from the current delivered by the secondary power converter.

[0055] Preferably, the drive system includes N main switches, a first end of each main switch is connected to the power supply grid, and a second end of each main switch is connected to the primary power converter of the drive unit to supply power from the grid to the primary power converter, and disconnecting the primary power converter of the target drive unit includes opening the main switch supplying power to the primary power converter.

[0056] Advantages:

[0057] - the electric motor of the target drive unit comprises a wound rotor comprising windings powered by a power supply module of the target drive unit,

[0058] Disconnecting the primary power converter of the target drive unit includes controlling a power supply module of the target drive unit such that the power supply module stops supplying power to windings of a wound rotor of an electric machine of the target drive unit.

[0059] The present invention provides a set of technical solutions, as follows.

[0060] Technical Solution 1. A drive system (1), comprising a connection circuit and N drive units (2, 3), each drive unit comprising a motor (12, 13), and a primary power converter (8, 9) configured to supply power to the motor, N being a non-zero integer, characterized in that the drive system further comprises:

[0061] - an auxiliary power converter (18) connected to each of the electric machines of the drive unit via the connecting circuit, and

[0062] - an auxiliary control circuit (100) configured to control the auxiliary power converter and configured to:

[0063] o connecting the auxiliary power converter (18) to the motor of a drive unit among the N drive units through the connecting circuit, the drive unit being a target drive unit,

[0064] o driving the electric machine from the auxiliary power converter (18),

[0065] o Disconnecting the primary power converter of the target drive unit from the associated electric machine of the target drive unit.

[0066] Technical Solution 2. A drive system according to Technical Solution 1, wherein the auxiliary control circuit (100) is also configured to detect a fault in one of the N drive units (2, 3), the target drive unit is the faulty drive unit, and when the fault is a ground fault or a short circuit, the auxiliary power converter (18) is also configured to control the motor to be operational before connecting the auxiliary power converter (18) to the motor if the motor (12, 13) of the faulty drive unit (2, 3) is operational.

[0067] Technical Solution 3. The drive system according to Technical Solution 1 or 2, further comprising a global control circuit (33), and wherein each drive unit (2, 3) further comprises a local control circuit (14, 15), wherein the local control circuit is configured to monitor the drive unit and control the primary power converter (8, 9) of the drive unit, the local control circuit of the target drive unit is configured to supply the first power to the motor of the target drive unit, and the global control circuit is configured to:

[0068] - controlling the local control circuit and the auxiliary control circuit of the target drive unit so that the sum of the power supplied by the primary power converter of the target drive unit and the power supplied by the auxiliary power converter is equal to the first power, the power supplied by the primary power converter of the target drive unit decreases over time, and the power supplied by the auxiliary power converter increases over time, and

[0069] - When the power supplied by the primary power converter of the target drive unit is zero and the power supplied by the auxiliary power converter is equal to the first power, controlling the auxiliary control circuit to disconnect the primary power converter of the target drive unit from the associated motor.

[0070] Technical solution 4. A drive system according to any one of technical solutions 1 to 3, wherein:

[0071] - each drive unit (2, 3) comprises a first switch (10, 11) connecting the primary power converter (8, 9) of the drive unit to the motor (12, 13) of the drive unit, and

[0072] - the connection circuit comprises a primary switch (19) and a first switch module (20), the first switch module (20) being configured to connect the motor (12, 13) of each drive unit (2, 3) to the primary switch (19), the auxiliary control circuit being configured to open the first switch of the target drive unit when the primary power converter is disconnected from the associated motor of the target drive unit.

[0073] Technical solution 5. A drive system according to any one of technical solutions 1 to 4, wherein:

[0074] - the electric motor (12, 13) of the target drive unit (2, 3) comprises a wound rotor comprising a winding powered by a power supply module (36, 37) of the target drive unit, and

[0075] - the auxiliary control circuit (100) is configured to control the power supply module of the target drive unit so that when the primary power converter of the target drive unit is disconnected, the power supply module stops supplying power to the winding of the wound rotor of the motor of the target drive unit.

[0076] Technical Solution 6. A drive system according to Technical Solution 5, wherein the connection circuit includes a second switch module (39) powered by a secondary power converter (38), and the auxiliary control circuit (100) is configured to control the second switch module, the secondary power converter and the power supply module of the target drive unit, so that when the auxiliary power converter is connected, the power supply module supplies power to the winding of the rotor of the target drive unit from the current delivered by the secondary power converter.

[0077] Technical solution 7. A method for controlling a drive system (1) comprising a connection circuit and N drive units, each drive unit (2, 3) comprising a motor (12, 13) and a primary power converter (8, 9) for supplying power to the motor, N being a non-zero integer, characterized in that the method comprises:

[0078] -(a) connecting the auxiliary power converter (18) to the motor of a drive unit among the N drive units through the connecting circuit, the drive unit being a target drive unit,

[0079] - (b) supplying power from the auxiliary power converter (18) to the electric machine, and

[0080] - (c) disconnecting the primary power converter of the target drive unit from the associated electric machine of the target drive unit.

[0081] Technical solution 8. The method according to technical solution 7 comprises:

[0082] - detecting a failure of one of the drive units before processing steps (a), (b), (c), the target drive unit being the failed drive unit,

[0083] - When the faulty drive unit is detected, processing step (c),

[0084] - processing step (a) when the primary power converter of the faulty drive unit is disconnected from the motor of the faulty drive unit, and

[0085] - supplying power from the auxiliary power converter (18) to the electric motor of the faulty drive unit.

[0086] Technical Solution 9. The method according to Technical Solution 8 also includes controlling the motor (12, 13) of the fault drive unit when the fault is a ground fault or a short circuit, and connecting the auxiliary power converter (18) to the motor if the motor is operable.

[0087] Technical solution 10. The method according to any one of technical solutions 7 to 9, wherein the primary power converter (8, 9) of the target drive unit supplies a first power to the motor of the target drive unit, and the method comprises:

[0088] - supplying power to the motor from the auxiliary power converter (18) comprises controlling the primary power converter and the auxiliary power converter (18) of the target drive unit so that the sum of the power supplied by the primary power converter of the target drive unit and the power supplied by the auxiliary power converter is equal to the first power, the power supplied by the primary power converter of the target drive unit decreases over time, and the power supplied by the auxiliary power converter increases over time, and

[0089] - disconnecting the primary power converter (8, 9) of the target drive unit from the associated electric machine when the power supplied by the primary power converter of the target drive unit is zero and the power supplied by the auxiliary power converter is equal to the first power.

[0090] Technical solution 11. A method according to any one of technical solutions 7 to 10, wherein:

[0091] - each drive unit (2, 3) comprises a first switch (10, 11) connecting the primary power converter to the motor (12, 13) of the drive unit, and

[0092] the connection circuit comprises a primary switch (19) and a first switching module (20), the first switching module (20) connecting the motor (12, 13) of each drive unit (2, 3) to the primary switch,

[0093] - the first switch (10, 11) of each drive unit (2, 3) is closed, the primary switch (19) is opened, and the first switch module (20) is configured so that any current flows through the first switch module,

[0094] - Disconnecting the primary power converter of the target drive unit comprises:

[0095] - Turning on the first switch of the target drive unit.

[0096] Technical solution 12. The method according to any one of technical solutions 7 to 11, wherein connecting the auxiliary power converter comprises:

[0097] - activating the auxiliary power converter (18) to deliver AC voltage,

[0098] - synchronizing the AC voltage delivered by the auxiliary power converter (18) with the AC voltage supplied to the electric motor of the target drive unit,

[0099] - closing the primary switch (19), and

[0100] - controlling the first switch module (20) to connect the motor of the target drive unit to the closed primary switch (19).

[0101] Technical Solution 13. A method according to Technical Solution 12, wherein the connection circuit includes a second switch module (39) powered by a secondary power converter, and connecting the auxiliary power converter includes controlling the second switch module, the secondary power converter and the power supply module of the target drive unit, so that the power supply module supplies power to the winding of the rotor of the target drive unit from the current delivered by the secondary power converter.

[0102] Technical Solution 14. According to the methods described in Technical Solutions 7 to 13, the drive system includes N main switches (6, 7), the first end of each main switch is connected to the power supply grid (G), and the second end of each main switch is connected to the primary power converter (8, 9) of the drive unit (2, 3) to supply power from the grid to the primary power converter, and disconnecting the primary power converter of the target drive unit includes opening the main switch that supplies power to the primary power converter.

[0103] Technical solution 15. A method according to any one of technical solutions 7 to 14, wherein:

[0104] - the electric motor (12, 13) of the target drive unit (2, 3) comprises a wound rotor, the wound rotor comprising a winding powered by a power supply module (36, 37) of the target drive unit,

[0105] Disconnecting the primary power converter of the target drive unit comprises controlling the power supply module of the target drive unit such that the power supply module stops supplying power to the winding of the wound rotor of the electric machine of the target drive unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0106] Other characteristics and advantages of the invention will emerge on reading the following description of embodiments of the invention, provided purely by way of non-limiting example and with reference to the accompanying drawings, in which:

[0107] Figure 1 Schematically illustrates a first example of a drive system according to the invention,

[0108] Figure 2 schematically illustrates a second example of a drive system according to the invention,

[0109] Figure 3 A first example of a method for controlling a drive system according to the present invention is illustrated, and

[0110] Figure 4 A second example of the method of controlling a drive system according to the present invention is illustrated. DETAILED DESCRIPTION

[0111] Figure 1 A first example of a drive system 1 is schematically illustrated.

[0112] The drive system 1 is connected to a grid G1 .

[0113] The drive system includes N drive units, where N is a non-zero integer.

[0114] Assume that N is equal to 2, so that the drive system comprises two drive units 2 , 3 .

[0115] In another embodiment, N may be equal to 1 or greater than 2.

[0116] Each drive unit 2, 3 may include: a transformer 4, 5, which includes a primary circuit connected to the second end of the main switch 6, 7; a primary power converter 8, 9, which includes an input connected to the secondary circuit of the transformer 4, 5; a first switch 10, 11, which includes a first end connected to the output of the primary power converter 8, 9; and a motor 12, 13.

[0117] Each drive unit 2 , 3 further comprises a local control circuit 14 , 15 which monitors the drive unit 2 , 3 and controls the primary power converter 8 , 9 , the main switch 6 , 7 and the first switch 10 , 11 of the drive unit 2 , 3 .

[0118] The main switches 6 , 7 and the first switches 10 , 11 include, for example, circuit breakers.

[0119] The second ends of the first switches 10 , 11 of the drive units 2 , 3 are connected to the motors 12 , 13 of the drive units 2 , 3 .

[0120] A first end of each main switch 6 , 7 is connected to the grid G1 .

[0121] Primary power converters 8 , 9 supply stator windings of electric machines 12 , 13 with power from grid G1 .

[0122] The drive system 1 also includes an auxiliary main switch 16, which may include an auxiliary transformer 17 including a primary circuit connected to the grid G1 via the main switch 16, an auxiliary power converter 18 including an input connected to the secondary circuit of the transformer 17, and an auxiliary control circuit 100 that controls the auxiliary main switch 16 and the auxiliary power converter 18 and is intended to communicate with the local control circuits 14, 15.

[0123] The auxiliary control circuit 100 is intended to connect the auxiliary power converter 18 to the motor of a drive unit of the N drive units 2 , 3 , which is a target drive unit, through a connecting circuit.

[0124] The auxiliary control circuit 100 is also intended to drive the electric machine from the auxiliary power converter 18 and to disconnect the primary power converter of the target drive unit from the associated electric machine of the target drive unit.

[0125] The auxiliary power converter 18 is intended to be connected to each of the electric machines 12 , 13 of the drive units 2 , 3 via a connecting circuit.

[0126] The connection circuit comprises a primary switch 19 and a first switch module 20 comprising an input 20a and N outputs 20b, 20c.

[0127] The auxiliary control circuit 100 is also intended to control the primary switch 19 and the first switching module 20 .

[0128] The primary switch 19 connects the output of the auxiliary power converter 18 to the input 20 a of the first switching module 20 .

[0129] Each drive unit 2 , 3 comprises a first connection point C12 , C13 between a first switch 10 , 11 of said drive unit 2 , 3 and a motor 12 , 13 of said drive unit 2 , 3 .

[0130] The first output 20b of the first switch module 20 is connected to the first connection point C12 of the first drive unit 2, and the second output 20c of the first switch module 20 is connected to the first connection point C13 of the second drive unit 3. Assuming that the machines 12, 13 and the grid G1 have three phases, the transformers 8, 9 are three-phase transformers.

[0131] Each drive unit 2, 3 further comprises a first current sensor 25, 26 between the main switch 6, 7 and the primary circuit of the transformer 4, 5 of the drive unit, and a second current sensor 27, 28 between the output of the primary power converter 8, 9 of the drive unit and the first switch 10, 11 of the drive unit 2, 3.

[0132] Each drive unit 2 , 3 comprises a voltage sensor 29 , 30 between the second switch 14 , 15 and the machine 12 , 13 of said drive unit 2 , 3 , for example between the first connection point C12 , C13 and the motor 12 , 13 of said drive unit 2 , 3 .

[0133] Each drive unit 2, 3 also comprises a leakage current detector 31, 32 to detect a fault of the machine 12, 13 of said drive unit, which fault may be a ground fault or a short circuit of the stator windings and the associated power supply cables.

[0134] The measured values ​​of the first current sensor 25 , the second current sensor 27 , the voltage sensor 29 and the leakage current detector 31 of the first drive unit 2 are supplied to the local control circuit 14 of the first drive unit 2 .

[0135] The measured values ​​of the first current sensor 26 , the second current sensor 28 , the voltage sensor 30 and the leakage current detector 32 of the second drive unit 3 are supplied to the local control circuit 15 of the first drive unit 3 .

[0136] The drive system 1 also comprises a global control circuit 33 intended to communicate with the local control circuits 14 , 15 and the auxiliary control circuit 100 .

[0137] In another embodiment, the machines 12, 13 and the grid G1 can have one, two or more than three phases, transformers 8, 9, an auxiliary transformer 17, main switches 6, 7, an auxiliary main switch 16, first switches 10, 11, a primary auxiliary switch 19 and switches 23, 24 of a first switching module 20 adapted to the number of phases.

[0138] Each machine 12 , 13 comprises a self-excited rotor, such as a permanent magnet rotor, an induction rotor or a reluctance rotor comprising a squirrel cage including bars or windings.

[0139] Figure 2 A second example of a drive system 1 is schematically illustrated.

[0140] A second example of a drive system 1 and Figure 1 The first example of a drive system 1 illustrated in is different in that each machine 12 , 13 comprises a wound rotor comprising a winding 34 , 35 supplied by a supply module 36 , 37 of the drive unit 2 , 3 , a secondary power converter 38 and a second switching module 39 .

[0141] Each power supply module 36, 37 includes a power converter 36a, 37a and a switch 36b, 37b powered by the second power grid G2.

[0142] A first end of a switch 36b, 37b of a power supply module 36, 37 of each drive unit 2, 3 is connected to a winding 34, 35 of a wound rotor of a machine 12, 13 of the drive unit 2, 3, and a second end of the switch 36b, 37b is connected to an output of a power converter 36a, 37a of the drive unit 2, 3.

[0143] The power converter 36a, 37a of each drive unit 2, 3 is intended to deliver a direct current DC at its output in order to power the windings of the machine 12, 13 of said drive unit 2, 3.

[0144] The secondary power converter 38 includes an input terminal connected to the second grid G2 and an output terminal connected to an input terminal 39 a of the second switching module 39 .

[0145] The secondary power converter 38 is intended to deliver a DC current at the input 39 a of the second switching module 39 .

[0146] In another embodiment, the secondary power converter 38 is intended to deliver AC current at the input 39a of the second switching module 39 to power the rotor of each machine 12, 13 through a brushless exciter.

[0147] The second switch module 39 further includes N output terminals 39 b and 39 c.

[0148] The first output end 39b of the second switch module 39 is connected to the first end of the switch 36b of the power supply module 36 of the first drive unit 2, and the second output end 39c of the second switch module 39 is connected to the first end of the switch 37b of the power supply module 37 of the second drive unit 3.

[0149] The second switch module 39 includes N switches 40 , 41 .

[0150] The first switch 40 of the second switch module 39 connects the first output terminal 39 b to the input terminal 39 a of the second switch module 39 , and the second switch 41 of the second switch module 39 connects the second output terminal 39 c to the input terminal 39 a of the second switch module 39 .

[0151] The secondary power converter 36 a and the switch 36 b of the power supply module 36 of the first drive unit 2 are controlled by the local control circuit 14 of said drive unit 2 .

[0152] The secondary power converter 37 a and the switch 37 b of the power supply module 37 of the second drive unit 3 are controlled by the local control circuit 15 of the drive unit 3 .

[0153] The secondary power converter 38 and the second switch module 39 are controlled by the auxiliary control circuit 100 .

[0154] Figure 3 An example of a first method of controlling the drive system 1 when a drive unit among the N drive units is default is illustrated.

[0155] It is assumed that the local control circuits 14 , 15 and the auxiliary control circuit 100 are activated by the global control circuit 33 .

[0156] It is also assumed that the N main switches 6, 7 and auxiliary main switches 16, N first and second switches 10, 11 of the N drive units 2, 3 are closed so that at least one current flows through the switches, and the primary power converters 8, 9 of the N drive units 2, 3 are controlled by the local control circuits 14, 15 of the drive units 2, 3 so that the power converters 8, 9 are in active mode, that is, the primary power converter 8 of the first drive unit 2 supplies power to the machine 12, and the primary power converter 9 of the second drive unit 3 supplies power to the machine 13.

[0157] The primary switch 19 and the N switches 23 , 24 of the first switching module 20 are opened, so that no current flows through the switches.

[0158] The auxiliary power converter 18 is controlled by the auxiliary control circuit 100 such that the auxiliary power converter 18 is in a standby mode, that is, the auxiliary power converter 18 does not deliver a voltage at its output terminal.

[0159] Furthermore, if the drive units 2, 3 include power supply modules 36, 37 ( Figure 2 ), the switches 36b, 37b of the power supply modules 36, 37 are closed, and the power converters 36a, 37a of the power supply modules 36, 37 of the N drive units 2, 3 are controlled by the local control circuits 14, 15 of the drive units 2, 3, so that the converters 36a, 37a are in active mode, that is, the power converter 36a of the power supply module 36 of the first drive unit 2 supplies power to the winding of the rotor of the machine 12 of the first drive unit 2, and the power converter 37a of the power supply module 37 of the second drive unit 3 supplies power to the winding of the rotor of the machine 13 of the second drive unit 3.

[0160] The N switches 40 , 41 of the second switching module 39 are open, so that no current flows through the switches, and the secondary power converter 38 is in standby mode, ie the auxiliary power converter 18 delivers no voltage at its output.

[0161] The auxiliary control circuit 100 monitors the local control circuits 14 , 15 of the drive units 2 , 3 .

[0162] In step 50 , the local control circuit 14 , 15 monitors and controls the drive unit 2 , 3 depending on the measured values ​​delivered by the first and second current sensors 25 , 26 , 27 , 28 and the voltage sensors 29 , 30 .

[0163] The local control circuits 14 , 15 also monitor the machines 12 , 13 based on the measured values ​​delivered by the leakage current detectors 31 , 32 .

[0164] If the local control circuit 14 , 15 detects that the drive unit 2 , 3 is still operating as planned (step 51 ), the method continues to step 50 .

[0165] If the local control circuit 14 , 15 detects that one of the drive units 2 , 3 is defaulted (step 51 ), or the auxiliary control circuit 100 detects that the local control circuit 14 , 15 is faulty, the method continues to step 52 .

[0166] It is assumed hereinafter that the first drive unit 2 is the default, so that the first drive unit 2 is the target drive unit.

[0167] From step 52 to step 54 , the auxiliary control circuit 100 disconnects the primary power converter 8 from the associated electric machine 12 of the failed first drive unit 2 .

[0168] In step 52 , the auxiliary control circuit 100 stops the primary power converter 8 of the first drive unit 2 , so that the output terminal of the primary power converter 8 does not deliver current.

[0169] In step 53 , the auxiliary control circuit 100 opens the first switch 10 of the first drive unit 2 and the switch 36 b of the power supply module 36 of the first drive unit 2 to stop supplying power to the winding of the rotor of the machine 12 .

[0170] If the machine 12 does not include a wound rotor, for example the machine 12 includes a permanent magnet rotor or a squirrel cage, the auxiliary control circuit 100 only opens the first switch 10 of the first drive unit 2 , which does not include the power supply module 36 .

[0171] In step 54 , the auxiliary control circuit 100 turns on the main switch 6 of the first drive unit 2 .

[0172] During steps 51 to 54 , the auxiliary control circuit 100 also identifies default components of the first drive unit 2 , such as the primary power converter 8 or the machine 12 .

[0173] The fault may be a default of the primary power converter 8 of the first drive unit 2 , such as a short circuit or a ground fault.

[0174] The fault may be a default of the machine 12 of the first drive unit 2 , such as a short circuit or a ground fault.

[0175] If the fault is a short circuit or a ground fault of the first drive unit 2 (step 55 ), then in step 56 the auxiliary control circuit 100 tests whether the machine 12 is still operable, so that the machine 12 supplied with power still works to drive the load on the rotor shaft.

[0176] If machine 12 is no longer operational (step 57), the method ends.

[0177] If the fault is not a short circuit and not a ground fault (step 55), or if the machine 12 is operable under the condition of a short circuit or a ground fault (step 56), the auxiliary control circuit 100 considers the primary power converter 8 of the first drive unit 2 to be defaulted.

[0178] In steps 58 to 61 , the auxiliary control circuit 100 connects the auxiliary power converter 18 to the motor 12 of the failed first drive unit 2 through the connection circuit.

[0179] In step 58 , the auxiliary control circuit 100 controls the auxiliary power converter 18 so that the power converter delivers an AC voltage at its output terminal, and controls the auxiliary power converter 18 so that the AC voltage delivered by the auxiliary power converter 18 is synchronized with the AC voltage supplied to the motor 12 of the target drive unit 2 .

[0180] In step 59 , when the AC voltage delivered by the auxiliary power converter 18 is synchronized with the AC voltage supplying the motor 12 of the target drive unit 2 , the auxiliary control circuit 100 closes the primary switch 19 and the first switch 23 of the first switch unit 20 .

[0181] In step 60 , the auxiliary control circuit 100 closes the first switch 40 of the second switch module 39 so that the winding 34 of the rotor of the machine 12 is powered by the secondary power converter 38 controlled by the auxiliary control circuit 100 .

[0182] If the machine 12 does not include a wound rotor, the method processes step 59 and continues to step 61 .

[0183] When a drive unit defaults and the default is not caused by a default of the machine of the drive unit, disconnecting the power converter of the drive unit and connecting an auxiliary power converter to the machine of the drive unit to power the machine allows increasing the operating rate of the machine, thereby reducing production losses of the default drive unit.

[0184] Furthermore, depending on the inertia of the rotor of the machine, the inertia of the load connected to the rotor, the commutation duration of switches 6, 7, 10, 11, 23, 24, 36b, 37b, 40, 41 and the duration of starting the auxiliary power converter 18, a switch from the power converter of the faulty drive unit to the auxiliary power converter powering the machine may occur such that the change in torque generated by the machine during the switch is reduced and smoothed by the inertia.

[0185] Figure 4 An example of a second method of controlling the drive system 1 is illustrated.

[0186] The second method is implemented by supplying power to the machine 12, 13 of the target drive unit selected from the N drive units 2, 3 through the auxiliary power converter 18 when the N drive units 2, 3 are not in failure, for example, performing maintenance operations of the target drive unit while continuing to supply power to the machine of the target drive unit.

[0187] It is assumed that the local control circuits 14 , 15 and the auxiliary control circuit 100 are activated by the global control circuit 33 .

[0188] It is also assumed that the N main switches 6, 7 and auxiliary main switches 16, N first and second switches 10, 11 of the N drive units 2, 3 are closed so that at least one current flows through the switches, and the primary power converters 8, 9 of the N drive units 2, 3 are controlled by the local control circuits 14, 15 of the drive units 2, 3 so that the power converters 8, 9 are in active mode, that is, the primary power converter 8 of the first drive unit 2 supplies power to the machine 12, and the primary power converter 9 of the second drive unit 3 supplies power to the machine 13.

[0189] The primary switch 19 and the N switches 23 , 24 of the first switching module 20 are opened, so that no current flows through the switches.

[0190] The auxiliary power converter 18 is controlled by the auxiliary control circuit 100 such that it is in standby mode, that is to say the auxiliary power converter 18 delivers no voltage at its output.

[0191] Furthermore, if the drive units 2, 3 include power supply modules 36, 37 ( Figure 2), the switches 36b, 37b of the power supply modules 36, 37 are closed, and the power converters 36a, 37a of the power supply modules 36, 37 of the N drive units 2, 3 are controlled by the local control circuits 14, 15 of the drive units 2, 3, so that the converters 36a, 37a are in active mode, that is, the power converter 36a of the power supply module 36 of the first drive unit 2 supplies power to the winding of the rotor of the machine 12 of the first drive unit 2, and the power converter 37a of the power supply module 37 of the second drive unit 3 supplies power to the winding of the rotor of the machine 13 of the second drive unit 3.

[0192] The N switches 40 , 41 of the second switching module 39 are open, so that no current flows through the switches, and the secondary power converter 38 is in standby mode, ie the auxiliary power converter 18 delivers no voltage at its output.

[0193] The auxiliary control circuit 100 monitors the local control circuits 14 , 15 of the drive units 2 , 3 .

[0194] It is assumed that the target drive unit is the first drive unit 2 , and the primary power converter 8 of the first drive unit 2 supplies the first power to the motor 12 of the first drive unit 2 .

[0195] During a step 70 , the global control circuit 33 receives a command to supply power to the machine 12 of the first drive unit 2 via the auxiliary power converter 18 and to switch off the primary power converter 8 of the first drive unit 2 , for example to perform maintenance operations.

[0196] The command is issued by the operator through a human-machine interface, such as a touch screen or buttons.

[0197] During a step 71 , the global control circuit 33 controls the auxiliary control circuit 100 to connect the auxiliary power converter 18 to the electric machine 12 of the first drive unit 2 via a connecting circuit.

[0198] The auxiliary control circuit 100 controls the auxiliary power converter 18 so that the power converter delivers an AC voltage at its output terminal and controls the auxiliary power converter 18 so that the AC voltage delivered by the auxiliary power converter 18 is synchronized with the AC voltage supplied to the motor 12 of the target drive unit 2 .

[0199] In step 72 , when the AC voltage delivered by the auxiliary power converter 18 is synchronized with the AC voltage supplying the motor 12 of the target drive unit 2 , the auxiliary control circuit 100 closes the primary switch 19 and the first switch 23 of the first switch unit 20 .

[0200] Auxiliary power converter 18 does not deliver power to machine 12 .

[0201] In step 73, the global control circuit 33 controls the local control circuit 14 and the auxiliary control circuit 100 of the first drive unit 2 so that the sum of the power supplied by the primary power converter 8 of the first drive unit 2 and the power supplied by the auxiliary power converter 18 is equal to the first power, so that the power supplied by the main power converter 8 of the first drive unit 2 decreases over time, and the power supplied by the auxiliary power converter 18 increases over time.

[0202] When the power supplied by the primary power converter 8 of the first drive unit 2 is zero and the power supplied by the auxiliary power converter 18 is equal to the first power, the primary power converter 8 of the first drive unit 2 is disconnected from the machine 12. Steps 52 to 54 are performed to disconnect the primary power converter 8 of the first drive unit.

[0203] If the machine 12 includes a wound rotor, the auxiliary control circuit 100 controls the local control circuit 14 to open the switch 36b of the power supply module 36 of the first drive unit 2 to stop supplying power to the winding of the rotor of the machine 12, and controls the first switch 40 of the second switch module 39 so that the winding 34 of the rotor of the motor 12 is powered by the secondary power converter 38.

[0204] The first switch 40 of the second switch module 39 and the switch 36 b of the power supply module are switched during one of the steps 71 , 72 , 73 , 74 , 52 , 54 .

[0205] The switching of the first switch 40 of the second switch module 39 and the switch 36 b of the power supply module may be simultaneous.

Claims

1. A drive system (1) comprising a connection circuit and N drive units (2, 3), each drive unit comprising a motor (12, 13), a primary power converter (8, 9) configured to supply power to the motor, N being a non-zero integer, characterized in that: The drive system further comprises: - an auxiliary power converter (18) connected to each of the electric machines of the drive unit via the connecting circuit, and - an auxiliary control circuit (100) configured to control the auxiliary power converter and configured to: o connecting the auxiliary power converter (18) to the motor of a drive unit among the N drive units through the connecting circuit, the drive unit being a target drive unit, o driving the electric machine from the auxiliary power converter (18), o Disconnecting the primary power converter of the target drive unit from the associated electric machine of the target drive unit.

2. The drive system according to claim 1, wherein: The auxiliary control circuit (100) is also configured to detect a fault in one of the N drive units (2, 3), the target drive unit being the faulty drive unit, and when the fault is a ground fault or a short circuit, the auxiliary power converter (18) is also configured to control the motor (12, 13) of the faulty drive unit (2, 3) to be operable before connecting the auxiliary power converter (18) to the motor if the motor is operable.

3. The drive system according to claim 1 or 2, further comprising a global control circuit (33), and wherein each drive unit (2, 3) further comprises a local control circuit (14, 15), the local control circuit being configured to monitor the drive unit and control the primary power converter (8, 9) of the drive unit, the local control circuit of the target drive unit being configured to supply a first power to the motor of the target drive unit, the global control circuit being configured to: - controlling the local control circuit and the auxiliary control circuit of the target drive unit so that the sum of the power supplied by the primary power converter of the target drive unit and the power supplied by the auxiliary power converter is equal to the first power, the power supplied by the primary power converter of the target drive unit decreases over time, and the power supplied by the auxiliary power converter increases over time, and - When the power supplied by the primary power converter of the target drive unit is zero and the power supplied by the auxiliary power converter is equal to the first power, controlling the auxiliary control circuit to disconnect the primary power converter of the target drive unit from the associated motor.

4. A drive system according to any one of claims 1 to 3, wherein: - each drive unit (2, 3) comprises a first switch (10, 11) connecting the primary power converter (8, 9) of the drive unit to the motor (12, 13) of the drive unit, and - the connection circuit comprises a primary switch (19) and a first switch module (20), the first switch module (20) being configured to connect the motor (12, 13) of each drive unit (2, 3) to the primary switch (19), the auxiliary control circuit being configured to open the first switch of the target drive unit when the primary power converter is disconnected from the associated motor of the target drive unit.

5. The drive system according to any one of claims 1 to 4, wherein: - the electric motor (12, 13) of the target drive unit (2, 3) comprises a wound rotor comprising a winding powered by a power supply module (36, 37) of the target drive unit, and - the auxiliary control circuit (100) is configured to control the power supply module of the target drive unit so that when the primary power converter of the target drive unit is disconnected, the power supply module stops supplying power to the winding of the wound rotor of the motor of the target drive unit.

6. The drive system according to claim 5, wherein: The connection circuit includes a second switch module (39) powered by a secondary power converter (38), and the auxiliary control circuit (100) is configured to control the second switch module, the secondary power converter and the power supply module of the target drive unit so that when the auxiliary power converter is connected, the power supply module supplies power to the winding of the rotor of the target drive unit from the current delivered by the secondary power converter.

7. A method for controlling a drive system (1) comprising a connection circuit and N drive units, each drive unit (2, 3) comprising an electric motor (12, 13) and a primary power converter (8, 9) for supplying power to the electric motor, N being a non-zero integer, characterized in that The method comprises: -(a) connecting the auxiliary power converter (18) to the motor of a drive unit among the N drive units through the connecting circuit, the drive unit being a target drive unit, - (b) supplying power from the auxiliary power converter (18) to the electric machine, and - (c) disconnecting the primary power converter of the target drive unit from the associated electric machine of the target drive unit.

8. The method according to claim 7, comprising: - detecting a failure of one of the drive units before processing steps (a), (b), (c), the target drive unit being the failed drive unit, - When the faulty drive unit is detected, processing step (c), - processing step (a) when the primary power converter of the faulty drive unit is disconnected from the motor of the faulty drive unit, and - supplying power from the auxiliary power converter (18) to the electric motor of the faulty drive unit.

9. The method of claim 8, further comprising controlling the motor (12, 13) of the faulty drive unit when the fault is a ground fault or a short circuit, and connecting the auxiliary power converter (18) to the motor if the motor is operable.

10. The method according to any one of claims 7 to 9, wherein: The primary power converter (8, 9) of the target drive unit supplies a first power to the motor of the target drive unit, and the method comprises: - supplying power to the motor from the auxiliary power converter (18) comprises controlling the primary power converter and the auxiliary power converter (18) of the target drive unit so that the sum of the power supplied by the primary power converter of the target drive unit and the power supplied by the auxiliary power converter is equal to the first power, the power supplied by the primary power converter of the target drive unit decreases over time, and the power supplied by the auxiliary power converter increases over time, and - disconnecting the primary power converter (8, 9) of the target drive unit from the associated electric machine when the power supplied by the primary power converter of the target drive unit is zero and the power supplied by the auxiliary power converter is equal to the first power.

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