Electronic device and method for determining characteristic parameters of a connection group and related power chain

Abstract

An electronic determination device (20) for determining at least one characteristic parameter of a connection group (18) connected between a converter (14) and an electric machine (12); the converter comprises at least two output terminals (26) and, for each output terminal, a switching branch (28) comprising at least one converter switch (36); the connection group comprises a filter (38) connected to an output terminal and a cable (40) connected between the filter and the electric machine; the filter comprises, for each output terminal, a respective electromagnetic coil (44) connected to said output terminal and a respective capacitor (46) connected to said coil; the determination device (20) comprises: - for each output terminal, a device switch (50) configured to be connected to the respective capacitor; - a generation module (52) configured to generate, by controlling the converter switches and each device switch, a voltage pulse (54) through the connection group; - an acquisition module (56) configured to acquire, after the generation of the respective voltage pulse, measurements of the respective current and voltage through the filter; and a calculation module (58) configured to calculate, from the respective current and voltage measurements, at least one characteristic parameter of the connection group.

Description

TECHNICAL FIELD

[0001] The invention relates to an electronic determination device for determining at least one characteristic parameter of a connection set connected between a converter and an electric machine.

[0002] The invention also relates to a power supply chain for an electric machine, comprising a converter, a connection set connected to an output of the converter and adapted to be connected to the electric machine, and an electronic determination device for determining at least one characteristic parameter of the connection set.

[0003] The invention also relates to a determination method for determining at least one characteristic parameter of a connection set connected between a converter and an electric machine, the method being implemented by such an electronic determination device.

[0004] The invention also relates to a computer program comprising software instructions for implementing such a determination method when executed by a processor. BACKGROUND

[0005] The invention relates to a characteristic of a connection set connected between a converter and an electric machine.

[0006] The use of electric machines is ubiquitous in the industrial world. Electric machines are electric motors consuming electric energy or electric generators producing electric energy, for example by wind power of a wind turbine or by tidal power of a hydroelectric turbine. Electric machines are usually connected to a power converter with a cable. The power converter produces a fast conversion at the end of the cable connected to said converter. At the other end of the cable connected to the electric machine, overvoltages appear at the terminals of the electric machine and leakage currents flow in the ground. This disturbance requires the use of an LC filter. Thus, a connection set connected between a converter and an electric machine usually comprises a cable and such a filter.

[0007] In order to optimize the performance of such a system comprising an electric machine and a power converter connected together via a connection set, the knowledge of the characteristic parameter(s) of said connection set is necessary.

[0008] The characteristic parameter(s) of the connection set can be determined beforehand, i.e. before running the system, for example by making sufficient measurements after manufacturing the cable and correspondingly the filter, or according to the data sheets of the cable and the corresponding filter.

[0009] However, the pre-determination of the characteristic parameter(s) of the connection group does not guarantee that the values of the characteristic parameter(s) remain the same throughout the use of the connection group. Typically, the capacitance of the capacitor of the filter decreases under the effect of ageing, for example by up to 30% of the initial value. Furthermore, the pre-defined cable length can also be further modified with the modification of the system. In the case of existing systems, it is difficult to know the length and the characteristics of the cable. Finally, the cable can be subjected to mechanical and thermal constraints, thereby modifying its geometry and the dielectric properties of the cable. Consequently, the characteristic parameter(s) of the cable can also be modified throughout the use of the connection device.

[0010] All these potential events require the implementation of a device for determining the characteristic parameter(s) of the connection group throughout its use.

[0011] Thus, it is known to use an impedance analyzer to determine the impedance of the filter, i.e. the inductance of the respective electromagnetic coil of the filter and the capacitance of the respective capacitor.

[0012] It is also known to use a Time Domain Reflectometry (TDR) device to determine the propagation time of the cable, as disclosed in the operating manual of the company TEKTRONIX entitled "TDR Impedance Measurements: A Foundation for Signal Integrity".

[0013] However, the use of such an impedance analyzer and / or such a time domain reflectometry device can be rather cumbersome. SUMMARY

[0014] Thus, the aim of the present invention is to provide an electronic determination device and a related method for determining at least one characteristic parameter of a connection group connected between a converter and an electric machine, which allows the determination of the characteristic parameter(s) to be easier and more convenient.

[0015] To this end, the subject of the present invention is an electronic determination device according to claim 1.

[0016] Thus, the determination device according to the present invention allows the use of the converter switch of the converter to generate a voltage pulse through the connection group, while controlling the device switch connected to the capacitor of the filter in an appropriate manner, then measuring the respective current(s) and voltage(s) through the filter, each characteristic parameter of the connection group being further calculated in a convenient manner from the respective measured current(s) and voltage(s).

[0017] The control of the device switch connected to the capacitor of the filter generally depends on the characteristic parameter to be determined, but also on the respective output terminal of the converter for which the characteristic parameter is determined.

[0018] According to other advantageous aspects of the application, according to any one of claims 2 to 12, the electronic determination device comprises one or several of the following features taken separately or according to any technically possible combination.

[0019] According to another advantageous aspect of the application, the converter is a DC / AC converter configured for converting a DC current into an AC current, and the electric machine is an AC electric machine.

[0020] According to claim 13, the subject of the application is also a power chain for an electric machine.

[0021] According to claim 14, the subject of the application is also a method for determining at least one characteristic parameter of a connection group connected between a converter and an electric machine.

[0022] The subject of the application is also a computer program according to claim 15. BRIEF DESCRIPTION OF DRAWINGS

[0023] The application will be better understood by reading the following description, given only as an example and with reference to the appended drawings, in which:

[0024] Figure 1 is a schematic view of a power chain for powering an electric machine according to the application, the power chain comprising a converter, a connection group connected to the output of the converter and adapted to be connected to the electric machine, and an electronic determination device for determining at least one characteristic parameter of the connection group;

[0025] Figure 2 is a simplified representation of the power chain in a first configuration for determining the characteristic parameter(s) of the connection group;

[0026] Figure 3 is a view representing the voltage and current curves in the connection group in the first configuration according to the first variant;

[0027] Figure 4 is a view similar to Figure 3 according to the second variant;

[0028] Figure 5 is a view similar to Figure 2 belonging to a second configuration for determining another characteristic parameter of the connection group;

[0029] Figure 6 is a view representing the voltage and current curves in the connection group in the second configuration;

[0030] Figure 7 is an equivalent of the connection group in the second configuration;

[0031] Figure 8is a view similar to Figure 2 which belongs to a third configuration for determining other characteristic parameter(s) of the connection group;

[0032] Figure 9 is an equivalent of the connection group in the third configuration;

[0033] Figure 10 is a view similar to Figure 2 which belongs to a fourth configuration for determining another characteristic parameter of the connection group;

[0034] Figure 11 is a view representing voltage and current curves of the connection group in the fourth configuration;

[0035] Figure 12 is an equivalent of the connection group in the fourth configuration; and

[0036] Figure 13 is a flowchart of a determination method for determining at least one characteristic parameter of a connection group according to the application, the method being implemented by Figure 1 a determination device. DETAILED DESCRIPTION

[0037] In Figure 1 , the power supply chain 10 for the electric machine 12 comprises a converter 14 adapted to be connected to a direct current power supply 16, a connection group 18 connected to an output of the converter 14 and adapted to be connected to the electric machine 12, and an electronic determination device 20 for determining at least one characteristic parameter Z0, Tp, Cc, L, C, F res of the connection group 18.

[0038] The electric machine 12 is preferably an AC electric machine. The electric machine 12 has P phases 22, P being an integer greater than or equal to 3. The electric machine 12 is a motor or a generator. In Figure 1 the example, the electric machine 12 is a three-phase electric machine, P being equal to 3, the three phases 22 being respectively noted u, v, w.

[0039] The converter 14 comprises input terminals 24, for example a first input terminal noted V+ and a second input terminal noted V-, and at least two output terminals 26. The converter 14 is preferably a DC / AC converter configured for converting a DC current received at the input terminals 24 into an AC current delivered to the output terminals 26. In Figure 1 the example, where P is equal to 3, the converter 14 comprises three output terminals 26. The converter 14 is for example an N-level converter, N being an integer greater than or equal to 2.

[0040] For each output terminal 26, the converter 14 further comprises a switching branch 28, a first switching half-branch 30 and a second switching half-branch 32 being connected in series between the two input terminals 24 and being connected to each other at an intermediate point 34, the first switching half-branch 30 being connected to the first input terminal V+, the second switching half-branch 32 being connected to the second input terminal V-, the intermediate point 34 being connected to the corresponding output terminal 26.

[0041] In the following description, each intermediate point 34 will be mixed with the corresponding output terminal 26 it is connected to, and will be respectively noted U, V, W according to the corresponding phase u, v, w.

[0042] Each switching half-branch 30, 32 comprises at least one converter switch 36, the converter switches 36 associated with the output terminals 26 noted U being noted Suj, the converter switches 36 associated with the output terminals 26 noted V being noted Svj, the converter switches 36 associated with the output terminals 26 noted W being noted Swj, where j is a positive integer representing the index of the corresponding converter switch 36.

[0043] Each converter switch 36 is switchable between a closed position in which a current flows through said switch, and an open position in which no current flows through said switch. Each converter switch 36 comprises at least one controllable interrupter, for example Figure 1 a transistor, preferably with a freewheeling diode (not shown) connected anti-parallel to this transistor.

[0044] In the example illustrated in Figure 1 , the converter 14 is a two-stage converter, N is equal to 2, and each switching half-branch 30, 32 comprises a single converter switch 36, the converter switches 36 of the first switching half-branch 30 being noted Sx1, the converter switches 36 of the second switching half-branch 32 being noted Sx2, where X is a variable representing the output terminal U, V, W to which the corresponding converter switch Sxj is connected.

[0045] As a variant not illustrated, the number of stages N of the converter 14 is greater than or equal to 3, and each switching half-branch 30, 32 comprises several converter switches 36. Each switching half-branch 30, 32 generally comprises N-1 converter switches 36.

[0046] The connection group 18 comprises a filter 38 connected to the output terminals 26 and a cable 40 connected between the filter 38 and the electric machine 12. For each output terminal 26, the cable 40 comprises a corresponding electrical conductor 42. For each output terminal 26, the filter 38 comprises a corresponding electromagnetic coil 44 connected to said output terminal 26 and a corresponding capacitor 46 connected to said coil 44 at a connection point 48, the corresponding capacitor 46 being drawn with respect to said coil 44 and to the corresponding conductor 42 of the cable 40.

[0047] The determining device 20 is configured to determine at least one characteristic parameter Z0, Tp, Cc, L, C, F of the connection group 18 res . Each characteristic parameter Z0, Tp, Cc, L, C, F res is selected from the group comprising: a characteristic impedance Z0 of the respective conductor 42 of the cable 40; a propagation time Tp associated with the respective conductor 42 of the cable 40; a parasitic capacitance Cc of the respective conductor 42 of the cable 40; an inductance L of the respective electromagnetic coil 44 of the filter 38; a capacitance C of the respective capacitor 46 of the filter 38; and a resonance frequency F of the connection group 18 res .

[0048] For each output terminal 26, the determining device 20 comprises a device switch 50 configured to be connected to the respective capacitor 46. The device switch 50 is denoted by Ku, Kv, Kw, respectively, depending on the respective output terminal U, V, W linked by the respective coil 44 and capacitor 46.

[0049] The determining device 20 further comprises a generating module 52 for generating, by controlling the converter switch 36 and each device switch 50, a voltage pulse 54 through the connection group 18; an acquisition module 56 for acquiring, after generating the respective voltage pulse 54, a measurement of the respective current and voltage through the filter 38; and a calculation module 58 for calculating, from the respective current and voltage measurement, at least one characteristic parameter Z0, Tp, Cc, L, C, F of the connection group 18 res .

[0050] In the example of Figure 1 , the determining device 20 comprises a processing unit 60 formed, for example, by a memory 62 and a processor 64 coupled to the memory 62.

[0051] In the example of Figure 1 , the generating module 52, the acquisition module 56 and the calculation module 58 are each implemented, i.e. embodied, for example, as software executable by the processor 64. The memory 62 of the processing unit 60 is adapted to store generating software configured to generate, by controlling the converter switch 36 and each device switch 50, a voltage pulse 54 through the connection group 18, acquisition software configured to acquire, after generating the respective voltage pulse 52, a measurement of the respective current and voltage through the filter 38, and calculation software configured to calculate, from the respective current and voltage measurement, at least one characteristic parameter Z0, Tp, Cc, L, C, F of the connection group 18 res . The processor 64 of the processing unit 60 is then configured to execute the generating software, the acquisition software and the calculation software.

[0052] As a variant not shown, the generation module 52, the acquisition module 56 and the calculation module 58 are in the form of programmable logic components, for example field programmable gate arrays or FPGAs, or in the form of application specific integrated circuits, for example application specific integrated circuits or ASICs.

[0053] When the device 20 is determined to be in the form of one or more software programs, i.e. in the form of computer programs, it can also be recorded on a computer readable medium (not shown). The computer readable medium is for example a medium capable of storing electronic instructions and coupled to the bus of a computer system. For example, the readable medium is an optical disk, a magneto-optical disk, a ROM memory, a RAM memory, any type of non-volatile memory (for example EPROM, EEPROM, FLASH, NVRAM), a magnetic or optical card. The computer program with the software instructions is then stored on the readable medium.

[0054] Each device switch 50 is switchable between a closed position in which a current flows through the switch and an open position in which no current flows through the switch. Each device switch 50 can be controlled by the generation module 52. Each device switch 50 is for example a relay, as shown. Figure 1

[0055] Each device switch 50 is configured to be connected at one end to a respective capacitor 46 of the filter 38 and at the other end to the other device switch(s) 50. In the example shown, Figure 1 The other end of the device switches 50 is connected in a star configuration. Alternatively, the other end of the device switches 50 is connected in a delta configuration.

[0056] In the example shown, Figure 1 The current delivered at each output terminal 26 and flowing through each respective electromagnetic coil 44 is denoted Iu, Iv, Iw respectively, depending on the corresponding phase u, v, w. The voltage at each output terminal 26, i.e. at the input of the filter 38, is denoted Uu_in, Uv_in, Uw_in respectively, depending on the corresponding phase u, v, w. Similarly, the voltage between the ends of each capacitor 46 of the filter 38 is denoted Uu, Uv, Uw respectively, depending on the corresponding phase u, v, w.

[0057] The generation module 52 is configured to generate, by controlling the converter switches 36 and each device switch 50, a voltage pulse 54 through the connection group 18. The generated voltage pulse 54 has an amplitude A which generally verifies the following equation:

[0058]

[0059] where A denotes the amplitude of the voltage pulse 54,

[0060] ​Ubus represents the voltage between the first input terminal V+ and the second input terminal V-, and

[0061] N represents the number of stages of the converter 14 .

[0062] exist Figures 1 to 13 In the example of , the converter 14 is a two-stage converter, and the voltage pulse 54 is generally generated between the null voltage and the voltage Ubus. In a variant where N is greater than or equal to 3, the voltage pulse 54 is generally generated between the null voltage and a voltage equal to A, or between voltages equal to A and 2A, etc.

[0063] The generation of such a voltage pulse of amplitude A at the respective output terminal 26 of the converter 14 by controlling the converter switch 36 is known per se.

[0064] The generating module 52 is, for example, configured to generate a voltage pulse 54 through the corresponding output terminal 26 by controlling the corresponding converter switch 36 of the first switching half-branch 30 for the output terminal 26 to be closed and the corresponding converter switch 36 of the second switching half-branch 32 for the output terminal 26 to be open, wherein, before the controlling, the corresponding converter switch 36 of the first switching half-branch 30 is initially open and the corresponding converter switch 36 of the second switching half-branch 32 is initially closed.

[0065] Furthermore, when the voltage pulse 54 has a predefined duration equal to the predefined time period dt, the generation module 52 is further configured to cut off the voltage pulse 54. Thus, the generation module 52 is configured to cut off the voltage pulse 54 after the predefined time period (dt) after the voltage pulse 54 is generated, for example, by controlling the aforementioned corresponding converter switch 36 of the first switching half-branch 30 for the output terminal 26 to be open and controlling the aforementioned corresponding converter switch 36 of the second switching half-branch 32 for the output terminal 26 to be closed.

[0066] The skilled person will understand that when the generation module 52 controls the (multiple) converter switches 36 to be closed, this means that the (multiple) converter switches 36 are switched to their closed positions; and respectively, when the generation module 52 controls the (multiple) converter switches 36 to be open, this means that the (multiple) converter switches 36 are switched to their open positions.

[0067] The generation module 52 is further configured to control each device switch 50 so that the voltage pulse 54 generated via the corresponding output terminal 26 by the aforementioned control of the converter switch 36 then flows along a specific path of the connection group 18, said path depending on the characteristic parameters to be calculated Z0, Tp, Cc, L, C, F resThis control of the device switch 50 will be described in more detail below with reference to Figure 1 and for each characteristic parameter Z0, Tp, Cc, L, C, F res .

[0068] The acquisition module 56 is configured to acquire, after the generation of the respective voltage pulse 54, the respective current(s) and voltage(s) measurements through the filter 38. The acquisition module 56 is generally configured to acquire the respective measurements of the current Iu, Iv, Iw through the electromagnetic coil 44 connected to the respective output terminal 26 and of the voltage Uu, Uv, Uw in the respective connection point 48 of the respective output terminal 26, at least during the time interval Figures 2 to 13 and depending on the respective phase u, v, w. Similarly, the acquisition of these measurements will be described in more detail below with reference to Figure 1 and each characteristic parameter Z0, Tp, Cc, L, C, F res .

[0069] The calculation module 58 is then configured to calculate, from said respective current(s) and voltage(s) measurements, at least one characteristic parameter Z0, Tp, Cc, L, C, F res of the connection group 18.

[0070] Calculation of the characteristic impedance Z0, the inductance L, the propagation time Tp and / or the parasitic capacitance Cc

[0071] When the at least one characteristic parameter to be determined is among the aforementioned characteristic impedance Z0, the inductance L, the propagation time Tp and the parasitic capacitance Cc, the generation module 52 is also configured to, before the generation of the voltage pulse 54 through the respective output terminal 26, control the device switch 50 to be open and the converter switch 36 of the second switching half-branch 32 to be closed for one output terminal 26 other than said respective output terminal 26.

[0072] The generated voltage pulse 54 will thus flow through the electromagnetic coil 44 connected to said respective output terminal 26, the cable 40, then back to the electromagnetic coil 44 connected to said other output terminal 26, as Figures 2 to 13 illustrated. In the example of Figure 2 , the respective output terminal 26 is the output noted U, said other output terminal 26 is the output noted V and the converter 14 is a two-stage converter of Figure 2 , the amplitude of the voltage pulse 54 being equal to Ubus.

[0073] Then, after generating the voltage pulse 54, the acquisition module 56 is configured to acquire respective measurements of the current Iu, Iv, Iw through the electromagnetic coil 44 connected to the respective output terminal 26, of the voltage Uu, Uv, Uw in the respective connection point 48 of the respective output terminal 26, and of the voltage Uv or Uw, Uu or Uw, Uu or Uv in the respective connection point 48 of the other output terminal 26.

[0074] When the characteristic parameter to be determined is the inductance L, the acquisition module 56 is further configured to acquire a measurement of the voltage Ubus between the first input terminal V+ and the second input terminal V-.

[0075] Then, the calculation module 58 is configured to calculate the characteristic impedance Z0 and / or the inductance L from the respective acquired measurements at the time t1, t1m after generating the voltage pulse 54, as shown in the examples of current Iu and voltage Uu, Uv in Figure 1 and Figure 3

[0076] The calculation module 58 is for example configured to calculate the characteristic impedance Z0 of the respective conductor 42 of the cable 40 according to the following equation:

[0077]

[0078] wherein Z0 denotes the characteristic impedance of the respective conductor 42,

[0079] Uu denotes the voltage in the respective connection point 48 of the output terminal 26,

[0080] Uv denotes the voltage in the respective connection point 48 of the other output terminal 26,

[0081] Iu denotes the current through the coil 44 connected to the output terminal 26, and

[0082] t1 denotes the time after generating the voltage pulse 54.

[0083] The calculation module 58 is for example configured to calculate the inductance L of the respective electromagnetic coil 44 of the filter 38 according to the following equation:

[0084]

[0085] wherein L denotes the inductance of the respective electromagnetic coil 44,

[0086] Uu denotes the voltage in the respective connection point 48 of the output terminal 26,

[0087] Uv denotes the voltage in the respective connection point 48 of the other output terminal 26,

[0088] ​Ubusdenotes the voltage between the first input terminal V+and the second input terminal V-, and

[0089] t1mrepresents the instant after the generation of the voltage pulse 54;

[0090] The instant t1mverifies preferably the following condition:

[0091]

[0092] where t0denotes the instant of generation of the voltage pulse 54,

[0093] Li denotes a predefined initial value of the inductance of the respective electromagnetic coil 44, and

[0094] Z 0_ref denotes a predefined reference value of the characteristic impedance of the respective conductor 42.

[0095] Alternatively, the calculation module 58 is configured to calculate said inductance L according to the following equation:

[0096]

[0097] where L denotes the inductance of the respective electromagnetic coil 44,

[0098] Z0denotes the characteristic impedance of the respective conductor 42,

[0099] Uu denotes the voltage in the respective connection point 48 of the output terminal 26,

[0100] Uv denotes the voltage in the respective connection point 48 of the further output terminal 26,

[0101] Ubusdenotes the voltage between the first input terminal V+and the second input terminal V-, and

[0102] ln denotes the natural logarithm, and

[0103] t1represents the instant after the generation of the voltage pulse 54;

[0104] The instant t1verifies preferably the following condition:

[0105] t1-t0≤ 2 · Tp_ref (6)

[0106] where t0denotes the instant of generation of the voltage pulse 54, and

[0107] Tp_ref denotes a predefined propagation time associated with the respective conductor 42 of the cable 40.

[0108] To calculate the propagation time Tp, the calculation module 58 is for example configured to detect the instant t3 of a change in slope of the voltage difference Ui-Uj (i index equal to u, v or w, j index equal to u, v or w and different from i) equal to the voltage Uu, Uv, Uw in the respective connection point 48 of the output terminal 26 minus the voltage Uv or Uw, Uu or Uw, Uu or Uv of the other output terminal 26, said change in slope occurring after the generation of the voltage pulse 54.

[0109] Figure 4 and Figure 3 said change in slope between the first slope SL1 and the second slope SL2 is illustrated in both cases. In a first case, the voltage pulse is cut off at the instant t2, preferably greater than the instant ti, after the generation of the voltage pulse 54, the first slope SL1 is negative and the second slope SL2 is positive. In a second case, the voltage pulse 54 is not cut off, the first slope SL1 and the second slope SL2 are both positive, the first slope SL1 is less than the second slope SL2.

[0110] Moreover, the calculation module 58 is for example configured to calculate the propagation time Tp associated with the respective conductor 42 of the cable 40 according to the following equation:

[0111]

[0112] where Tp represents the propagation time associated with the respective conductor 42 of the cable 40,

[0113] to represents the instant of generation of the voltage pulse 54, and

[0114] t3 represents the instant of change in slope of the voltage difference Ui-Uj;

[0115] Moreover, the calculation module 58 is for example configured to calculate the parasitic capacitance Cc of the respective conductor 42 of the cable 40 according to the following equation:

[0116]

[0117] where Cc represents the parasitic capacitance of the respective conductor 42 of the cable 40,

[0118] Tp represents the propagation time associated with the respective conductor 42 of the cable 40, and

[0119] Z0 represents the characteristic impedance of the respective conductor 42, for example calculated according to equation (2).

[0120] Reference will now be made to Figure 4, in particular with reference to the first sequence SEQ-1, to explain the operation of the power chain 10 for calculating the characteristic impedance Z0, the inductance L, the propagation time Tpand / or the parasitic capacitance Cc, in particular the operation of determining the device 20, Figure 13 a flowchart representing a method for determining at least one characteristic parameter Z0, Tp, Cc, L, C, F res of the connection group 18.

[0121] The first sequence SEQ-1 shows the determination method when the at least one characteristic parameter to be determined is among the aforesaid characteristic impedance Z0, inductance L, propagation time Tpand parasitic capacitance Cc, in Figure 13 the example in which the respective output terminal 26 is the output terminal noted U, the other output terminal 26 is the output terminal noted V and the converter 14 is Figures 2 to 4 a two-stage converter.

[0122] In an initial step 100, the determining device 20 controls, via its generation module 52, all the device switches 50 (also noted Kx, x being a variable representing the respective phase u, v, w) and all the converter switches 36 (also noted Sx) to be open before generating the voltage pulse 54 through the respective output terminal 26.

[0123] In a next step 110, the determining device 20 controls, via its generation module 52, the converter switch 36 of the second switching half-branch 32 for the respective output terminal 26 and the converter switch 36 of the second switching half-branch 32 for one output terminal 26 other than said respective output terminal 26 to be closed. In Figure 1 the example in which the respective output terminal 26 is the output U and the other output terminal 26 is the output terminal V, the generation module 52 thus controls the converter switches Su2 and Sv2 to be closed.

[0124] Then, in order to generate the voltage pulse 54 at the respective output terminal 26, in a next step 115, the determining device 20 controls, via its generation module 52, the converter switch 36 of the first switching half-branch 30 for the respective output terminal 26 to be closed and the converter switch 36 of the second switching half-branch 32 for said respective output terminal 26 to be open. Thus, in Figures 2 to 4 the example in which the respective output terminal 26 is the output U and the other output terminal 26 is the output terminal V, the generation module 52 controls the converter switch Su1 to be closed and the converter switch Su2 to be open.

[0125] In a next step 120, at the instant tl, tlm following the generation of the voltage pulse 54, the device 20 determines, via its acquisition module 56, the respective measurement of the current Iu, Iv, Iw passing through the electromagnetic coil 44 connected to the respective output terminal 26, the respective measurement of the voltage Uu, Uv, Uw in the respective connection point 48 of the respective output terminal 26 and the respective measurement of the voltage Uv or Uw, Uu or Uw, Uu or Uv in the respective connection point 48 of the other output terminal 26. In Figures 2 to 4 In the example of Fig. 2, the acquisition module 56 thus acquires the respective measurements of the current Iu, the voltage Uu and the voltage Uv.

[0126] Then, in a next step 130, the device 20 determines, via its calculation module 58, the characteristic impedance Z0 of the respective conductor 42 of the cable 40 according to equation (2); and in a next step 140, the inductance L of the respective electromagnetic coil 44 of the filter 38 according to equation (3) or (5). In Figures 2 to 4 In the example of Fig. 2, the calculation module 58 calculates the characteristic impedance Z0 of the respective conductor 42 associated with the phase u and the inductance L of the electromagnetic coil 44 associated with the phase u.

[0127] Optionally, to cut off the voltage pulse 54 at the aforementioned instant t2, in a next step 150, the device 20 determines, via its generation module 52, the control of the opening of the converter switch 36 of the first switching half-branch 30 and the closing of the converter switch 36 of the second switching half-branch 32 for the respective output terminal 26. Thus, in Figures 2 to 4 In the example of Fig. 2, the generation module 52 controls the opening of the converter switch Su1 and the closing of the converter switch Su2.

[0128] In a next step 160, after the instant t2, the device 20 determines, via its acquisition module 56, the respective measurement of the voltage Uu, Uv, Uw in the respective connection point 48 of the respective output terminal 26 and the respective measurement of the voltage Uv or Uw, Uu or Uw, Uu or Uv in the respective connection point 48 of the other output terminal 26 in order to calculate the slope of the voltage difference Ui-Uj. In Figures 2 to 4 In the example of Fig. 2, the acquisition module 56 thus acquires the respective measurements of the voltage Uu and the voltage Uv in order to calculate the slope of the voltage difference (Uu-Uv) during step 160.

[0129] Then, in a next step 165, the device 20 determines, via its acquisition module 56, whether the voltage difference Ui-Uj has a change of slope, i.e. whether the slope of the voltage difference Ui-Uj changes from a first slope SL1 to a second slope SL2.

[0130] If the test is positive, i.e. if the acquisition module 56 has detected a slope variation, the acquisition module 56 measures the instant t3 of the slope variation of the voltage difference Ui-Uj, i.e. Figures 2 to 4 the slope variation of the voltage difference Uu-Uv in the example of Fig. 2.

[0131] Otherwise, if the test is negative, i.e. if the acquisition module 56 has not detected a slope variation, the acquisition module 56 returns to step 160 for the acquisition of the respective measurement values of the subsequent instants.

[0132] After the measurement of the instant t3 of the slope variation in step 170, in the next step 180 the device 20 determines, via its calculation module 58, the propagation time Tp associated with the respective conductor 42 of the phase u according to equation (7); and in the next step 190 the parasitic capacitance Cc of the respective conductor 42 of the phase u is calculated according to equation (8). In the example of Fig. 2, the calculation module 58 calculates the propagation time Tp associated with the respective conductor 42 of the phase u and the parasitic capacitance Cc of the respective conductor 42 of the phase u. Step 190 is the last step of the first sequence SEQ-1. Figures 2 to 4

[0133] At the end of the first sequence SEQ-1, the device 20 can branch to a second sequence SEQ-2 focused on the calculation of the capacitance C and / or the alternative calculation of the propagation time Tp and / or the parasitic capacitance Cc, or to a third sequence SEQ-3 focused on the calculation of the resonance frequency F res or return to the initial step 100 of the first sequence SEQ-1 to calculate new value(s) of the characteristic impedance Z0, the inductance L, the propagation time Tp and / or the parasitic capacitance Cc for another phase v, w or the same phase u.

[0134] Calculation of the capacitance C and alternative calculation of the propagation time Tp and / or the parasitic capacitance Cc

[0135] When the at least one characteristic parameter to be determined is among the aforesaid capacitance C, propagation time Tp and parasitic capacitance Cc, the generation module 52 is further configured to, before generating the voltage pulse 54 through the respective output terminal 26, control the device switch 50 for the respective output terminal 26 to be closed, control the device switch(s) 50 for the output terminals 26 other than the respective output terminal 26 to be opened, control the converter switch(s) 36 of the second switching half-branch 32 for the respective output terminal 26 to be closed, and control the converter switch(s) 36 of the other switching half-branches to be opened.

[0136] The generated voltage pulse 54 will therefore flow through the electromagnetic coil 44 connected to the respective output terminal 26, then through the cable 40 and the capacitor 46 associated with the respective output terminal 26, as​Figures 2 to 4 and Figure 5 are shown in Fig. 1. Figure 7 and Figure 5 In the example of Fig. 1, the respective output terminals 26 are output terminals denoted U, the converters 14 are two-stage converters of the type Figure 7 , and the amplitudes A of the voltage pulses 54 are equal to Ubus.

[0137] The generation module 52 is further configured to control the respective converter switches 36 of the switching half-branches of the output terminals 26 to cut off the voltage pulses 54 after a predefined time period dt after the generation of the voltage pulses 54 through the respective output terminals 26.

[0138] The acquisition module 56 is then configured to acquire, after the predefined time period dt, a respective measurement of the current Iu, Iv, Iw through the electromagnetic coils 44 connected to the output terminals 26 and / or a respective measurement of the voltage Uu, uv, Uw in the respective connection points 48 of the output terminals 26.

[0139] The calculation module 58 is for example configured to calculate the capacitance C of the respective capacitor 46 of the filter 38 according to the following equation:

[0140]

[0141] wherein C denotes the capacitance of the respective capacitor 46 of the filter 38,

[0142] Tper denotes the period of the current Iu, Iv, Iw through the electromagnetic coils 44 connected to the output terminals 26 or the period of the voltage Uu, uv, Uw in the respective connection points 48 of the output terminals 26, and

[0143] L denotes the inductance of the respective electromagnetic coil 44.

[0144] The period Tper of the current Iu and the voltage Uu for example is shown in Fig. 2. Figure 1

[0145] As an alternative to the calculation of the aforementioned parasitic capacitance Cc, the calculation module 58 is configured to calculate the parasitic capacitance Cc of the respective conductor 42 of the cable 40 according to the following equation:

[0146]

[0147] wherein Cc denotes the parasitic capacitance of the respective conductor 42 of the cable 40,

[0148] C denotes the capacitance of the respective capacitor 46 of the filter 38, and

[0149] Ceq is defined according to the following equation:

[0150] ​

[0151] wherein Tper represents the period of the current Iu, Iv, Iw through the electromagnetic coil 44 connected to the output terminal 26 or the period of the voltage Uw, Uu, uv in the corresponding connection point 48 of the output terminal 26; and

[0152] L represents the inductance of the corresponding electromagnetic coil 44;

[0153] As an alternative to the aforementioned calculation of the propagation time Tp, the calculation module 58 is configured to calculate the propagation time Tp associated with the respective conductor 42 of the cable 40 according to the following equation:

[0154] Tp=Cc·Zo (12)

[0155] where Tp represents the propagation time associated with the corresponding conductor 42 of the cable 40,

[0156] Cc represents the parasitic capacitance of the corresponding conductor 42 of the cable 40, and

[0157] Z0 represents the characteristic impedance of the corresponding conductor 42, for example calculated according to equation (2).

[0158] As another alternative to the calculation of the aforementioned parasitic capacitance Cc and / or propagation time Tp, the period Tper used in equation (11) represents the period of the voltage differences Uu-Uv, Uu-Uw, Uv-Uu, Uv-Uw, Uw-Uu, Uw-Uv; this voltage difference is equal to the voltage Uu, uv, Uv in the corresponding connection point 48 for the output terminal 26 minus the voltage Uv, Uw, Uu, Uw, Uu, Uv in the corresponding connection point 48 for the other output terminal 26.

[0159] According to the other alternative, the generating module 52 is configured to, before generating the voltage pulse 54 through the corresponding output terminal 26, control the device switch 50 for the corresponding output terminal 26 and the device switch 50 for one output terminal 26 other than the corresponding output terminal 26 to be closed, control the other (multiple) device switches 50 to be opened, control the (multiple) converter switches 36 of the second switching half-branch 32 for the corresponding output terminal 26 to be closed, and control the (multiple) converter switches 36 of the other switching half-branch to be opened.

[0160] Thus, the generated voltage pulse 54 will flow through the electromagnetic coil 44 connected to the corresponding output terminal 26, and then flow through the cable 40, the capacitor 46 associated with the corresponding output terminal 26, and the capacitor 46 associated with the other output terminal 26, as shown in FIG. Figure 6 and Figure 8 As shown. Figure 9 andFigure 8 In the example of FIG. 1 , the corresponding output terminal 26 is output terminal U, the other output terminal 26 is output terminal V, and the converter 14 is Figure 9 For a two-stage converter, the amplitude A of the voltage pulse 54 is equal to Ubus.

[0161] The generation module 52 is further configured to control the respective converter switch 36 of the switching half-branch of said output terminal 26 to switch off the voltage pulse 54 after a predetermined time period dt after the generation of the voltage pulse 54 through said respective output terminal 26 .

[0162] The acquisition module 56 is then configured to acquire respective measured values ​​of the voltage Uu, Uv, Uw in the respective connection point 48 for the respective output terminal 26 and the voltage Uu, Uv, Uw in the respective connection point 48 for the further output terminal 26 after a predefined time period dt.

[0163] The calculation module 58 is, for example, configured to calculate the parasitic capacitance Cc according to equations (10) and (11) and / or to calculate the propagation time Tp according to equation (12).

[0164] Now refer to Figure 1 , in particular with reference to the second sequence SEQ-2, the operation of the power supply chain 10 , in particular the operation of the determination device 20 , for calculating the capacitance C, the propagation time Tp and / or the parasitic capacitance Cc is explained, Figure 13 Flowchart showing a method for determining at least one characteristic parameter Z0, Tp, Cc, L, C, Fres of a connection group 18 .

[0165] The second sequence SEQ-2 shows a method for determining at least one characteristic parameter to be determined among the aforementioned capacitance C, propagation time Tp and / or parasitic capacitance Cc. Figure 13 In the example of FIG. 1 , the corresponding output terminal 26 is an output terminal denoted as U, the other output terminal 26 is an output terminal denoted as V, and the converter 14 is Figures 5 to 9 Two-stage converter.

[0166] In an initial step 200 of the second sequence SEQ-2, before generating the voltage pulse 54 through the corresponding output terminal 26, the determination device 20 controls all device switches 50 (also noted as Kx) and all converter switches 36 (also noted as Sx) to be open via its generation module 52.

[0167] In a next step 210, it is determined that the device 20, via its generation module 52, controls the device switch 50 for the respective output terminal 26 to be closed, controls the device switch(s) 50 for the output terminal(s) 26 other than the respective output terminal 26 to be opened, controls the converter switch 36 of the second switching half-branch 32 for the respective output terminal 26 to be closed, and controls the converter switch(s) 36 of the other switching half-branches to be opened. In the example of Figure 1 , the respective output terminal 26 is the output terminal U and the other output terminal 26 is the output terminal V, thus the generation module 52 controls the device switches Ku and the converter switch Su2 to be closed and the device switches Kv and Kw to be opened.

[0168] Then, in order to generate the voltage pulse 54 at the respective output terminal 26, in a next step 215, it is determined that the device 20, via its generation module 52, controls the converter switch 36 of the first switching half-branch 30 for the respective output terminal 26 to be closed and controls the converter switch 36 of the second switching half-branch 32 for the respective output terminal 26 to be opened. Thus, in the example of Figures 5 to 7 , the generation module 52 controls the converter switch Su1 to be closed and the converter switch Su2 to be opened.

[0169] In a next step 220, after a predetermined time period dt after the generation of the voltage pulse 54, it is determined that the device 20 cuts off the voltage pulse 54 by controlling, via its generation module 52, the converter switch 36 of the first switching half-branch 30 for the respective output terminal 26 to be opened and the converter switch 36 of the second switching half-branch 32 for the respective output terminal 26 to be closed. Thus, in the example of Figures 5 to 9 , the generation module 52 controls the converter switch Su1 to be opened and the converter switch Su2 to be closed.

[0170] Then, in a next step 230, it is determined that the device 20, by means of its acquisition module 56, acquires the respective measured values of the current Iu, Iv, Iw through the electromagnetic coil 44 connected to the respective output terminal 26 and / or the respective measured values of the voltage Uu, Uv, Uw in the respective connection point 48 for the respective output terminal 26. Thus, in the example of Figures 5 to 9 , the acquisition module 56 obtains the respective measured values of the current Iu and / or the voltage Uu.

[0171] In a next step 240, it is determined that the device 20, via its acquisition module 56, calculates the consecutive values of the period (denoted as Tper1, Tper2) of the current Iu, Iv, Iw through the electromagnetic coil 44 connected to the output terminal 26 or the voltage Uu, Uv, Uw in the respective connection point 48 for the output terminal 26.

[0172] Then, in a next step 250, the device 20 determines, via its acquisition module 56, whether the absolute value of the difference between these successive values Tperl and Tper2 is less than a low threshold value e. The threshold value e comprises for example between 0.5 ps and 2 ps.

[0173] If the test is positive, i.e. if the successive values Tperl and Tper2 are close enough to consider that the value of the period Tper is stable, then in a next step 260 the acquisition module 56 sets the period Tper equal to one of the last successive acquired values Tperl and Tper2, for example Tperl.

[0174] Otherwise, if the test is negative, i.e. if the successive values Tperl and Tper2 are not close enough to consider that the value of the period Tper is stable, then the acquisition module 56 returns to step 240 to compute a next successive value Tperl, Tper2.

[0175] After setting the period Tper, in a next step 270, the device 20 determines, via its computation module 58 and according to equation (9), the capacitance C of the corresponding capacitor 46 of the filter 38.

[0176] In a next step 275, as an alternative to the aforementioned computation of the parasitic capacitance Cc, the device 20 determines, via its computation module 58, the parasitic capacitance Cc according to equations (10) and (11), and / or the propagation time Tp according to equation (12).

[0177] As another alternative to the aforementioned computation of the parasitic capacitance Cc and / or of the propagation time Tp, the period Tper used in equation (11) represents the period of the voltage difference Ui-Uj, which is equal to the voltage in the corresponding junction 48 of the output terminal 26 minus the voltage in the corresponding junction 48 of the other output terminal 26.

[0178] According to said another alternative, in step 210, the generation module 52 controls the device switch 50 for the corresponding output terminal 26 and the device switch 50 for one output terminal 26 other than the corresponding output terminal 26 to be closed, controls the other device switch 50 to be open, controls the converter switch(s) 36 of the second switch half branch 32 for the corresponding output terminal 26 to be closed, and controls the converter switch(s) 36 of the other switch half branch to be open. In Figures 5 to 9 and Figure 8 In the example of U and V, the corresponding output terminal 26 is the output terminal U and the other output terminal 26 is the output terminal V, thus the generation module 52 controls the device switches Ku and Kv and the converter switch Su2 to be closed and the device switch Kw to be open.

[0179] Then, after step 270 or 275, in a next step 280, the device 20 determines whether the value of the capacitance C tested via its computing module 58 has decreased with respect to the reference value Ci, for example using the following equation:

[0180]

[0181] where C denotes the capacitance of the respective capacitor 46 of the filter 38,

[0182] Ci denotes the reference value Ci of said capacitance, and

[0183] σ denotes a percentage threshold not exceeding 20%.

[0184] For example, the reference value Ci is a predefined value or is determined when the system is first commissioned. The percentage threshold σ is generally less than 20%.

[0185] If the test is negative, i.e. the value of the capacitance C has not decreased with respect to the reference value Ci, the device 20 determines to end the second sequence SEQ-2.

[0186] Otherwise, if the test is positive, i.e. the value of the capacitance C has decreased with respect to the reference value Ci, in a next step 290, the device 20 determines to trigger an alarm to indicate the aging of the respective capacitor 46 of the filter 38. Then, the device 20 determines to end the second sequence SEQ-2.

[0187] At the end of the second sequence SEQ-2, the device 20 can branch to a third sequence SEQ-3 for computing the resonance frequency F res , or to the first sequence SEQ-1 for computing the characteristic impedance Z0, the inductance L, the propagation time Tp and / or the parasitic capacitance Cc, or back to the initial step 200 of the second sequence SEQ-2 for computing new value(s) of the capacitance C, the propagation time Tp and / or the parasitic capacitance Cc for another phase v, w or the same phase u.

[0188] The computation of the resonance frequency Fres

[0189] When the characteristic parameter to be determined is the resonance frequency F res , the generating module 52 is configured to control the device switch 50 to be closed and the converter switch(es) 36 of the second switching half-branch 32 for each output terminal 26 to be closed before generating the voltage pulse 54 passing through the respective output terminal 26.

[0190] The generated voltage pulse 54 will thus flow through each electromagnetic coil 44 and each capacitor 46 of the filter 38 and through the cable 40, as Figure 9 and Figure 10 illustrated in Figure 12 andFigure 10 In the example, the corresponding output terminal 26 is the output terminal denoted as U, and the converter 14 is Figure 12 For a two-stage converter, the amplitude A of the voltage pulse 54 is equal to Ubus.

[0191] The generation module 52 is further configured to control the respective converter switch 36 of the switching half-branch of said output terminal 26 to switch off the voltage pulse 54 after a predefined time period dt after the generation of the voltage pulse 54 through said respective output terminal 26 .

[0192] The acquisition module 56 is then configured to acquire corresponding measured values ​​of the voltages Uu, Uv, Uw in the respective connection points 48 of the output terminal 26 and of the voltages Uv, Uw, Uu, Uw, Uu, Uv in the respective connection points 48 of the further output terminal 26 after a predefined time period dt.

[0193] The calculation module 58 is configured, for example, to calculate the resonant frequency F of the connection group 18 according to the following equation: res :

[0194]

[0195] Among them, F res represents the resonant frequency of the connection group 18,

[0196] Tper represents the period of the voltage differences Uu-Uv, Uu-Uw, Uv-Uu, Uv-Uw, Uw-Uu, Uw-Uv, which are equal to the voltages Uu, Uv, Uw in the corresponding connection points 48 for the output terminal 26 minus the voltages Uv, Uw, Uu, Uw, Uu, Uv in the corresponding connection points 48 for the other output terminal 26.

[0197] Now refer to Figure 1 , in particular with reference to the third sequence SEQ-3, the operation of the power supply chain 10 for calculating the resonant frequency Fres, in particular the operation of the determination device 20, is explained, Figure 13 represents at least one characteristic parameter Z0, Tp, Cc, L, C, F for determining the connection group 18 res Flowchart of the method.

[0198] The third sequence SEQ-3 shows that when the characteristic parameter to be determined is the resonant frequency F res The method for determining when Figure 13 In the example, the corresponding output terminal 26 is the output terminal denoted as U, and the converter 14 is Figures 10 to 12 Two-stage converter.

[0199] In an initial step 300 of the third sequence SEQ-3, the device 20 is determined, via its generation module 52, to control all (multiple) converter switches 36 (also noted Sx) to be open before generating the voltage pulse 54 through the respective output terminal 26.

[0200] In a next step 310, the device 20 is determined, via its generation module 52, to control all device switches 50 (also noted Kx) to be closed and to control (multiple) converter switches 36 of the second switching half-branch 32 for each output terminal 26 to be closed. Thus, in the example of Figure 1 the generation module 52 controls the device switches Kx and the converter switches Sx2 to be closed.

[0201] Then, in order to generate the voltage pulse 54 at the respective output terminal 26, in a next step 315, the device 20 is determined, via its generation module 52, to control the converter switches 36 of the first switching half-branch 30 for the respective output terminal 26 to be closed and the converter switches 36 of the second switching half-branch 32 for said respective output terminal 26 to be open. Thus, in the example of Figures 10 to 12 the generation module 52 controls the converter switches Sui to be closed and the converter switches Su2 to be open.

[0202] In a next step 320, after a predefined time period dt after the generation of the voltage pulse 54, the device 20 is determined to cut off the voltage pulse 54 by controlling, via its generation module 52, the converter switches 36 of the first switching half-branch 30 for the respective output terminal 26 to be open and the converter switches 36 of the second switching half-branch 32 for said respective output terminal 26 to be closed. Thus, in the example of Figures 10 to 12 the generation module 52 controls the converter switches Sui to be open and the converter switches Su2 to be closed.

[0203] Then, in a next step 330, the device 20 is determined, via its acquisition module 56, to acquire a respective measured value of the voltage difference Ui-Uj equal to the voltage Uu, Uv, Uw in the respective connection point 48 for said output terminal 26 minus the voltage Uv or Uw, Uu or Uw, Uu or Uv in the respective connection point 48 for said other output terminal 26. Figures 10 to 12 Figures 10 to 12 In the example of

[0204] In a next step 340, the device 20 is determined, via its acquisition module 56, to calculate successive values (noted Tperl, Tper2) of the period of said voltage difference Ui-Uj for said respective output terminal 26.

[0205] Then, in a next step 350, the device 20 determines, via its acquisition module 56, whether the absolute value of the difference between these successive values Tperl and Tper2 is less than a threshold value e.

[0206] If the test is positive, i.e. if the successive values Tperl and Tper2 are close enough for considering that the value of the period Tper is stable, the acquisition module 56 sets the period Tper equal to one of the last successive acquired values Tperl and Tper2, for example Tperl, and proceeds to a next step 360.

[0207] Otherwise, if the test is negative, i.e. if the successive values Tperl and Tper2 are not close enough for considering that the value of the period Tper is stable, the acquisition module 56 returns to step 340 for computing a subsequent successive value Tperl, Tper2.

[0208] After setting the period Tper, in step 360, the device 20 determines, via its computation module 58, the resonant frequency F of the filter 38 according to equation (14) res In this case, the period Tper is also called the resonance period and is noted Tres.

[0209] At the end of the third sequence SEQ-3, the device 20 can branch to the first sequence SEQ-1 for computing the characteristic impedance Z0, the inductance L, the propagation time Tp and / or the parasitic capacitance Cc, or to the second sequence SEQ-2 for computing the capacitance C, the propagation time Tp and / or the parasitic capacitance Cc, or return to the initial step 300 of the third sequence SEQ-3 for computing a new value(s) of the resonant frequency F res .

[0210] The first sequence SEQ-1, the second sequence SEQ-2 and the third sequence SEQ-3 are generally repeated for each output terminal 26, i.e. for the outputs V and W. In other words, the first sequence SEQ-1, the second sequence SEQ-2 and the third sequence SEQ-3 are preferably performed for each output terminal 26 of the converter 14, i.e. for each phase u, v, w.

[0211] This determination method is performed at the beginning of the power supply chain 10 and is repeatable at regular intervals, for example at a user-defined frequency.

[0212] For example, in case of humidity and temperature that vary a lot within a day, this determination method can be performed two to three times a day to adjust the elements of the power supply chain 10, such as the capacitance value C of the respective capacitor 46 of the filter 38, the parasitic capacitance Cc of the respective conductor 42 of the cable 40 and / or the resonant frequency F of the connection group 18 res .

[0213] Another example is to detect the aging of the components of the power supply chain 10, in particular the aging of the connection group 18, in particular the aging of the capacitor 46 of the filter 38. Therefore, the determined characteristic parameters Z0, Tp, Cc, L, C, F res are stored regularly in a database, for example periodically, for example monthly. The evolution of the determined characteristic parameter(s) is thus evaluated to identify possible changes in value and evolution rates, thereby anticipating aging of the elements of the filter 38 and the cable 40.

[0214] Another use of the determination device 20 and the determination method according to the invention is to determine the break position of the cable 40 based on the determined propagation time Tp.

[0215] Thus, the electronic determination device 20 and the determination method according to the invention allow an easier and more convenient determination of the characteristic parameter(s) Z0, Tp, Cc, L, C, F res .

Claims

1. An electronic determination device (20) for determining at least one characteristic parameter of a connection group (18) connected between a converter (14) and an electric machine (12), the converter (14) comprising a first and a second input terminal (24), at least two output terminals (26), and for each output terminal (26) a switching branch (28) having a first and a second switching half-branch (30, 32) connected in series between the two input terminals and connected to each other at an intermediate point (34), the first switching half-branch (30) being connected to the first input terminal and the second switching half-branch (32) being connected to the second input terminal, the intermediate point (34) being connected to the output terminal (26), each switching half-branch comprising at least one converter switch (36); the connection group (18) comprising a filter (38) connected to the output terminal (26) and a cable (40) connected between the filter (38) and the electric machine (12); the cable (40) comprising for each output terminal (26) a respective electrical conductor (42); the filter (38) comprising for each output terminal (26) a respective electromagnetic coil (44) connected to the output terminal (26) and a capacitor (46) connected to the coil (44) in a connection point (48), the capacitor (46) being drawn off with respect to the coil (44) and to the respective conductor (42) of the cable (40); the electronic determination device (20) comprising: for each output terminal (26) a device switch (50) configured to be connected to the respective capacitor (46); a generation module (52) configured to generate, by controlling the converter switches (36) and each device switch (50), a voltage pulse (54) through the connection group (18); an acquisition module (56) configured to acquire, after the generation of the respective voltage pulse (54), a measurement of the respective current and voltage through the filter (38); and a calculation module (58) configured to calculate, from the respective current and voltage measurement, at least one characteristic parameter of the connection group (18).

2. The apparatus (20) of claim 1, wherein, each characteristic parameter being selected from the group consisting of: a characteristic impedance of the respective conductor (42) of the cable (40); a propagation time associated with the respective conductor (42) of the cable (40); a parasitic capacitance of the respective conductor (42) of the cable (40); an inductance of the respective electromagnetic coil (44) of the filter (38); a capacitance of the respective capacitor (46) of the filter (38); and a resonance frequency of the connection group (18).

3. The apparatus (20) according to claim 1 or 2, wherein the generation module (52) being configured to generate the voltage pulse (54) through the respective output terminal (26) by controlling: the respective converter switch (36) of the first switching half-branch (30) for the output terminal (26) to be closed, and the respective converter switch (36) of the second switching half-branch (32) for the output terminal (26) to be open, wherein, prior to said controlling, a respective converter switch (36) of said first switching half-branch (30) is initially open and a respective converter switch (36) of said second switching half-branch (32) is initially closed.

4. The apparatus (20) according to claim 1 or 2, wherein If said at least one characteristic parameter is among a characteristic impedance of a respective conductor (42) of the cable (40), an inductance of a respective electromagnetic coil (44) of the filter (38), a propagation time associated with a respective conductor (42) of the cable (40) and a parasitic capacitance of a respective conductor (42) of the cable (40), said generating module (52) is configured to control, prior to generating the voltage pulse (54) through the respective output terminal (26): a device switch (50) is open and a converter switch (36) of a second switching half-branch (32) for one output terminal (26) other than said output terminal (26) is closed; and wherein the acquisition module (56) is configured to acquire a respective measurement of a current through an electromagnetic coil (44) connected to said output terminal (26), a respective measurement of a voltage in a respective connection point (48) of said output terminal (26) and a respective measurement of a voltage in a respective connection point (48) of the other output terminal (26).

5. The apparatus (20) of claim 4, wherein, said calculation module (58) is configured to calculate the characteristic impedance of a respective conductor (42) of the cable (40) and / or the inductance of a respective electromagnetic coil (44) of the filter (38) from the respective measurement of the current through the electromagnetic coil (44) connected to said output terminal (26), the respective measurement of the voltage in the respective connection point (48) of said output terminal (26) and the respective measurement of the voltage in the respective connection point (48) of the other output terminal (26) at a time instant after the generation of the voltage pulse (54).

6. The apparatus (20) of claim 5, wherein, said acquisition module (56) is configured to acquire a measurement of a voltage between the first input terminal and the second input terminal, and wherein said calculation module (58) is configured to calculate the inductance of a respective electromagnetic coil (44) of the filter (38) according to the following equation: wherein L denotes the inductance of the respective electromagnetic coil (44), Iu denotes the current of the respective electromagnetic coil (44), Uu denotes the voltage in the respective connection point (48) of said output terminal (26), Uv denotes the voltage in the respective connection point (48) of the other output terminal (26), Ubus denotes the voltage between the first input terminal and the second input terminal, and t1m denotes the time instant after the generation of the voltage pulse (54).

7. The apparatus (20) of claim 5, wherein, said acquisition module (56) is configured to acquire a measurement of a voltage between the first input terminal and the second input terminal, and wherein said calculation module (58) is configured to calculate the inductance of a respective electromagnetic coil (44) of the filter (38) according to the following equation: wherein L denotes the inductance of the respective electromagnetic coil (44), Z0 denotes the characteristic impedance of the respective conductor (42), Uu denotes the voltage in the respective connection point (48) of said output terminal (26), Uv denotes the voltage in the respective connection point (48) for the further output terminal (26), Ubus denotes the voltage between the first input terminal and the second input terminal, In denotes the natural logarithm, and t1 denotes the time instant after the generation of the voltage pulse (54).

8. The apparatus (20) of claim 4, wherein, The calculation module (58) is configured to detect the time instant of a slope change of a voltage difference, the voltage difference being equal to the voltage in the respective connection point (48) for the output terminal (26) minus the voltage in the respective connection point (48) for the further output terminal (26), the slope change occurring after the generation of the voltage pulse (54), and wherein the calculation module (58) is configured to calculate the propagation time associated with the respective conductor (42) of the cable (40) according to the following equation: wherein Tp denotes the propagation time associated with the respective conductor (42) of the cable (40), t0 denotes the time instant of the generation of the voltage pulse (54), and t3 denotes the time instant of the slope change of the voltage difference.

9. The apparatus (20) according to claim 1 or 2, wherein, If the at least one characteristic parameter is the capacitance of the respective capacitor (46) of the filter (38), the generation module (52) is configured to control, before the generation of the voltage pulse (54) through the respective output terminal (26): a device switch (50) for the output terminal (26) to be closed, a device switch (50) for an output terminal (26) other than the output terminal (26) to be opened, a converter switch (36) of the second switching half-branch (32) for the output terminal (26) to be closed, and a converter switch (36) of the other switching half-branch to be opened; the generation module (52) is further configured to control, after a predefined time period after the generation of the voltage pulse (54) through the output terminal (26), the respective converter switch (36) of the switching half-branch for the output terminal (26) to cut off the voltage pulse (54); wherein the acquisition module (56) is configured to acquire, after the predefined time period, a respective measurement of the current through the electromagnetic coil (44) connected to the output terminal (26) and / or a respective measurement of the voltage in the respective connection point (48) for the output terminal (26).

10. The apparatus (20) according to claim 1 or 2, wherein, If the at least one characteristic parameter is among the propagation time associated with the respective conductor (42) of the cable (40) and the parasitic capacitance of the respective conductor (42) of the cable (40), the generation module (52) is configured to control, before the generation of the voltage pulse (54) through the respective output terminal (26): a device switch (50) for the output terminal (26) and a device switch (50) for an output terminal (26) other than the output terminal (26) to be closed, a further device switch (50) to be opened, a converter switch (36) of the second switching half-branch (32) for the output terminal (26) to be closed, and a converter switch (36) of the other switching half-branch to be opened; the generation module (52) is further configured to control the respective converter switch (36) of the switching half-branch of the output terminal (26) to cut off the voltage pulse (54) after a predefined time period after the generation of the voltage pulse (54) through the output terminal (26); and wherein the acquisition module (56) is configured to acquire a respective measurement of the current through an electromagnetic coil (44) connected to the output terminal (26) and / or a respective measurement of the voltage in a respective connection point (48) of the output terminal (26) after the predefined time period.

11. The apparatus (20) according to claim 1 or 2, wherein, If the at least one characteristic parameter is the resonance frequency of the connection group (18), the generation module (52) is configured to control, before the generation of the voltage pulse (54) through the respective output terminal (26): the device switch (50) to be closed, and the converter switch (36) of the second switching half-branch (32) for each output terminal (26) to be closed; and the generation module (52) is further configured to control the respective converter switch (36) of the switching half-branch of the output terminal (26) to cut off the voltage pulse (54) after a predefined time period after the generation of the voltage pulse (54) through the output terminal (26); and wherein the acquisition module (56) is configured to acquire a respective measurement of the voltage in a respective connection point (48) of the output terminal (26) and a respective measurement of the voltage in a respective connection point (48) of another output terminal (26) after the predefined time period.

12. The apparatus (20) according to claim 1 or 2, wherein, The converter (14) is an N-level converter, each switching half-branch comprising N-1 converter switches (36), N being an integer greater than or equal to 2.

13. A power chain (10) for an electric machine (12), the power chain (10) comprising: a converter (14) comprising a first input terminal and a second input terminal, at least two output terminals (26), and for each output terminal (26) a switching branch (28) having a first switching half-branch (30) and a second switching half-branch (32) connected in series between the two input terminals and to each other at an intermediate point (34), the first switching half-branch (30) being connected to the first input terminal and the second switching half-branch (32) being connected to the second input terminal, the intermediate point (34) being connected to the output terminal (26), each switching half-branch comprising at least one converter switch (36); the generation module (52) is further configured to control the respective converter switch (36) of the switching half-branch of the output terminal (26) to cut off the voltage pulse (54) after a predefined time period after the generation of the voltage pulse (54) through the output terminal (26); and wherein the acquisition module (56) is configured to acquire a respective measurement of the current through an electromagnetic coil (44) connected to the output terminal (26) and / or a respective measurement of the voltage in a respective connection point (48) of the output terminal (26) after the predefined time period. If the at least one characteristic parameter is the resonance frequency of the connection group (18), the generation module (52) is configured to control, before the generation of the voltage pulse (54) through the respective output terminal (26): the device switch (50) to be closed, and the converter switch (36) of the second switching half-branch (32) for each output terminal (26) to be closed; and the generation module (52) is further configured to control the respective converter switch (36) of the switching half-branch of the output terminal (26) to cut off the voltage pulse (54) after a predefined time period after the generation of the voltage pulse (54) through the output terminal (26); and wherein the acquisition module (56) is configured to acquire a respective measurement of the voltage in a respective connection point (48) of the output terminal (26) and a respective measurement of the voltage in a respective connection point (48) of another output terminal (26) after the predefined time period. The converter (14) is an N-level converter, each switching half-branch comprising N-1 converter switches (36), N being an integer greater than or equal to 2. a connection group (18) connected to the converter (14) and adapted to be connected to the electric machine (12), the connection group (18) comprising a filter (38) connected to the output terminals (26) and a cable (40) connected between the filter (38) and the electric machine (12); the cable (40) comprises a respective electrical conductor (42) for each output terminal (26); the filter (38) comprises, for each output terminal (26), a respective electromagnetic coil (44) connected to said output terminal (26) and a respective capacitor (46) connected to said coil (44) in a connection point (48), the respective capacitor (46) being drawn with respect to said coil (44) and to the respective conductor (42) of the cable (40); and an electronic determination device (20) for determining at least one characteristic parameter of the connection group (18), wherein the electronic determination device (20) is according to any one of the preceding claims.

14. A method for determining at least one characteristic parameter of a connection group (18) connected between a converter (14) and an electric machine (12), the converter (14) comprising a first and a second input terminal (24), at least two output terminals (26), and a switching branch (28) for each output terminal (26), the switching branch (28) having a first and a second switching half-branch (30, 32) connected in series between the two input terminals and connected to each other at an intermediate point (34), the first switching half-branch (30) being connected to the first input terminal and the second switching half-branch (32) being connected to the second input terminal, the intermediate point (34) being connected to said output terminal (26), each switching half-branch comprising at least one converter switch (36); the connection group (18) comprising a filter (38) connected to the output terminals (26) and a cable (40) connected between the filter (38) and the electric machine (12); the cable (40) comprises a respective electrical conductor (42) for each output terminal (26); the filter (38) comprises, for each output terminal (26), a respective electromagnetic coil (44) connected to said output terminal (26) and a capacitor (46) connected to said coil (44) in a connection point (48), the capacitor (46) being drawn with respect to said coil (44) and to the respective conductor (42) of the cable (40); the method being implemented by an electronic determination device (20) comprising a device switch (50) for each output terminal (26) configured to be connected to the respective capacitor (46), the method comprising the steps of: generating, by controlling the converter switches (36) and each device switch (50), a voltage pulse (54) through the connection group (18); after generating the respective voltage pulse (54), acquiring a measurement of the respective current and voltage through the filter (38); and calculating at least one characteristic parameter of the connection group (18) from the respective current and voltage measurements.

15. A computer program comprising software instructions which, when executed by a processor, implement the method according to claim 14.

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