Arrangement for power conversion and power drive

Abstract

An arrangement (2) for power conversion and electric drive comprising a power converter (201) comprising three branches (202), an electric motor (203) comprising three open-end stator windings (204) each having a first end and a second end, and a power switch (205). The first ends of the stator windings (204) are connected to respective ones of the three branches (202) of the power converter (201), and the second ends of the stator windings (204) are connected together and have the same potential. The power switch (205) is used to selectively disconnect one of the second ends of the stator windings (204) from all other second ends to establish at most two different potentials. The established at most two different potentials of the second ends of the stator windings (204) can be connected to respective ones of the branches (206) of a grid interface (207) connected to the arrangement (2).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to charging in electric vehicle (EV) applications. To this end, the present disclosure provides an arrangement for power conversion and power drive, a method of operating the arrangement, and a system comprising the arrangement. BACKGROUND

[0002] Most EV architectures rely on physically separated charging and traction functions implemented by on-board charger (OBC) and traction converter / inverter, respectively. As the name suggests, OBC is always on-board, requires dedicated space, needs to be carried inside the car, and cannot provide any additional functionality while the car is in motion. This implies high capital expenditure (CAPEX) and operational expenditure (OPEX).

[0003] However, the charging and drive functions of EVs cannot usually be used simultaneously. Exemplary attempts to combine charging and drive functions together in the same hardware imply a number of major limitations.

[0004] For example, fully integrated solutions are limited in functionality and operation. This makes EV systems inflexible and unable to address the range anxiety of most EV users. Charging of three-phase grid is implemented through an extra non-shared converter, or by using more than one motor or using a multi-phase machine. In some other cases, charging of three-phase grid generates torque. Obviously, this is detrimental to efficiency, damages the life of mechanical components, and generates noise and vibrations. SUMMARY

[0005] In view of the above-mentioned disadvantages, there is a need to reduce the overall size and cost of the system for charging and traction drive in electric vehicle applications, whether it is single-phase or three-phase charging operation.

[0006] This object is achieved by the embodiments defined in the attached independent claims. Further embodiments are listed in the dependent claims as well as in the following description and the drawings.

[0007] A first aspect of the present disclosure provides an arrangement for power conversion and electric drive. The arrangement comprises a power converter comprising three branches; an electric motor comprising three open-end stator windings each having a first end and a second end; and a power switch. The first ends of the stator windings are connected to respective ones of the three branches of the power converter, and the second ends of the stator windings are connected together and have the same potential. The power switch is used to selectively disconnect one of the second ends of the stator windings from all other second ends to establish at most two different potentials. The established at most two different potentials of the second ends of the stator windings can be connected to respective branches of a grid interface connected to the arrangement.

[0008] As used herein, a power converter can refer to a device capable of converting electrical energy from one form to another, for example between alternating current and direct current and / or between direct current and alternating current, changing voltage or frequency; or some combination of these. In particular, a power converter can comprise a switched mode power converter.

[0009] As used herein, a stator can refer to a fixed part of a rotating system, for example an electric machine. In an electric machine, a stator can comprise a plurality of windings to provide a rotating magnetic field to drive a rotor.

[0010] As used herein, a power switch can refer to a switch designed for high voltage and / or high current applications. In particular, a power switch can comprise a power semiconductor device.

[0011] According to an implementation of the first aspect, the arrangement further comprises an inductor having a first end and a second end. The first end of the inductor is connected to a further branch of the power converter; and the second end of the inductor is connected to a further branch of the grid interface.

[0012] As used herein, an inductor can refer to a passive electrical component that is capable of storing energy in a magnetic field when an electric current flows through the magnetic field. An inductor is characterized by its inductance, which is the ratio of the voltage across the inductor to the rate of change of current through it.

[0013] This configuration enables the connection of the charging mode of the EV to the three-phase grid without generating any torque and makes use of all the power electronics already existing for the traction system and the motor inductances. This saves space and improves power density, efficiency and reliability.

[0014] According to an implementation of the first aspect, the inductor has the same inductance as the stator windings.

[0015] This configuration provides a reasonable trade-off in view of the different operating modes of the arrangement.

[0016] According to an implementation of the first aspect, the power switch is configured to disconnect one of the second ends of the stator winding from all other second ends to establish two different potentials. The established two different potentials of the second ends of the stator winding can be connected to the respective branches of the grid interface.

[0017] This configuration enables a charging mode of the EV to be connected to a single-phase grid.

[0018] According to an implementation of the first aspect, the power switch is configured to not disconnect one of the second ends of the stator winding from all other second ends to establish a single potential.

[0019] According to an implementation of the first aspect, the established single potential of the second ends of the stator winding can be connected to one of the respective branches of the grid interface.

[0020] This configuration enables another charging mode of the EV to be connected to a single-phase grid.

[0021] According to an implementation of the first aspect, the power converter is configured to regulate an electrical parameter on a demand side of the power converter.

[0022] This configuration enables bidirectional operation of the power converter and the arrangement. Thus, the arrangement is able to charge an energy storage such as a battery from a grid and to generate torque using the stored electrical power. Furthermore, if required, the arrangement is able to return stored electrical power to the grid.

[0023] According to an implementation of the first aspect, the established single potential of the second ends of the stator winding is not connected to the respective branches of the grid interface.

[0024] This configuration enables a traction mode of the EV.

[0025] According to an implementation of the first aspect, the power converter can be operated according to a direct torque control (DTC), a field oriented control (FOC), a model predictive control (MPC), or an open-loop control strategy and is configured to regulate a torque of the electric motor according to a torque reference.

[0026] Torque as used herein can refer to a rotational equivalent of a linear force generated by the electric machine to affect propulsion of the EV.

[0027] These configurations increase the customizability to various EV requirements.

[0028] According to an implementation of the first aspect, the arrangement further comprises a further power switch for connecting the second end of the inductor to the established single potential of the second end of the stator winding.

[0029] This configuration extends the possibility of connection in traction mode by reducing common mode currents and improving fault tolerance capabilities.

[0030] According to an implementation of the first aspect, the power converter is configured to perform AC / AC power conversion. The first end of the stator winding can be connected to the respective branch of the AC side of the power converter.

[0031] Alternatively, the power converter is configured to perform AC / DC power conversion. The first end of the stator winding can be connected to the respective branch of the AC side of the power converter.

[0032] These configurations improve the customizability to various EV requirements.

[0033] According to an implementation of the first aspect, the power converter comprises a parallel connection of at least three independently controlled half-bridges providing the respective branch of the power converter.

[0034] This configuration enables a modular multi-cell architecture of the power converter.

[0035] According to an implementation of the first aspect, the power converter comprises a parallel connection of at least three independently controlled two-level 2L half-bridges.

[0036] This configuration based on 2L half-bridges providing two DC voltage levels implies low complexity.

[0037] According to an implementation of the first aspect, the power converter comprises a parallel connection of at least three independently controlled n-level nL half-bridges. The number of levels n is higher than 2.

[0038] This configuration based on nL half-bridges providing additional DC voltage levels reduces the losses and stress of the switching elements and is particularly suitable for high voltage applications.

[0039] According to an implementation of the first aspect, the arrangement is connectable to the grid interface comprising an electromagnetic interference, EMI, filter and a full-pole grid disconnection switch providing the respective branch of the grid interface.

[0040] This configuration improves EMI suppression and increases the safety of operation in EV charging mode.

[0041] According to an implementation of the first aspect, the electric machine is an induction machine or a permanent magnet synchronous machine.

[0042] An asynchronous (or induction) electric machine as used herein can refer to an AC driven electric machine in which the current required to produce torque in the rotor is obtained by electromagnetic induction from the magnetic field of the stator windings. In other words, the rotational speed of an induction machine must be slightly slower than the AC period in order to induce a current in the rotor windings.

[0043] A synchronous electric motor as used herein can refer to an AC driven electric machine in which, at steady state, the rotation of the rotor is synchronized with the frequency of the supply current and the rotational period is exactly an integer multiple of the AC period. In other words, a synchronous electric machine rotates at a rate that is locked to the line frequency. Permanent magnet synchronous electric machines use permanent magnets embedded in the rotor to produce a constant magnetic field.

[0044] These configurations increase the customizability to various EV requirements.

[0045] A second aspect of the present disclosure provides a system. According to the first aspect or any one of its embodiments, the system comprises an arrangement; a grid interface connected to the electric machine of the arrangement; an energy storage interface connected to the power converter of the arrangement, and an energy storage connected to the energy storage interface.

[0046] The system enables charging of an energy storage, e.g. a battery, of an EV from a grid, generating torque using stored electrical energy, and even returning stored electrical energy to the grid if needed.

[0047] A third aspect of the present disclosure provides a method of operating an arrangement for power conversion and power drive. The arrangement comprises a power converter comprising three branches; an electric machine comprising three open-end stator windings each having a first end and a second end; and a power switch. The second ends of the stator windings are connected together and have the same potential; and the power switch is used to selectively disconnect one of the second ends of the stator windings from a star configuration to establish at most two different potentials. The method comprises connecting the first ends of the stator windings to respective ones of the three branches of the power converter; selectively disconnecting one of the second ends of the stator windings from all other second ends to establish at most two different potentials; and connecting the established at most two different potentials of the second ends of the stator windings to respective branches of a grid interface connected to the arrangement.

[0048] This enables connection of a charging mode of an EV to a three-phase grid without generating any torque and with the use of all power electronics already existing for the traction system and the electric machine inductances. This saves space and increases power density, efficiency and reliability.

[0049] According to an implementation of the third aspect, the method further comprises utilizing the arrangement according to the first aspect or any of the implementations thereof.

[0050] Hence, the above-mentioned device features and associated advantages also hold by transference in connection with the method according to the third aspect.

[0051] A fourth aspect of the present disclosure provides a computer program comprising program code for performing the method according to the second aspect or any of the implementations thereof, when implemented on a processor of the arrangement according to the first aspect or any of the implementations thereof.

[0052] It is worth noting that all devices, elements, units and methods described in the present disclosure can be implemented in software or hardware elements or any combination of them. All steps which are described in the present disclosure performed by the various entities as well as the functions described to be performed by the various entities are intended to mean that the respective entity is adapted to perform the respective steps and functionalities. Even if a particular function or step to be performed by external entities is not reflected in the description of a particular detailed element of that entity performing that particular step or function, it should be clear for a skilled person that these methods and functions can be implemented in respective software or hardware elements or any kind of combination thereof. BRIEF DESCRIPTION OF DRAWINGS

[0053] The above aspects will be explained in the following description of various embodiments with reference to the drawings, in which:

[0054] Fig. 1 shows an exemplary EV architecture;

[0055] Figure 2 An arrangement according to an example of the present disclosure for single-phase charging is shown;

[0056] Figure 3 An arrangement according to an example of the present disclosure for three-phase charging is shown;

[0057] Figure 4 An arrangement according to another example of the present disclosure for single-phase charging is shown;

[0058] Figure 5 An arrangement according to an example of the present disclosure for torque (i.e. drive) generation is shown;

[0059] Figure 6 An arrangement according to an example of the present disclosure for torque generation with additional fault tolerance is shown;

[0060] Figure 7 An arrangement according to an example of the present disclosure comprising an AC / AC power converter is shown;

[0061] Figure 8An arrangement according to an example of the disclosure comprising an AC / DC power converter is shown;

[0062] Figure 9 A general scheme of a power converter according to an arrangement of an example of the disclosure is shown;

[0063] Figure 10 A general scheme of a grid interface connectable to an arrangement according to an example of the disclosure is shown;

[0064] Figure 11 A system according to an example of the disclosure is shown; and

[0065] Figure 12 A flowchart of a method according to an example of the disclosure operating an arrangement is shown. DETAILED DESCRIPTION

[0066] The above aspects will now be described with reference to various embodiments shown in the drawings.

[0067] Features of the embodiments can be combined with each other unless otherwise stated.

[0068] The drawings are to be considered in the illustrative sense only and the elements shown in the drawings are not necessarily to scale. Rather, various elements are represented so that their function and general purpose become apparent to a person skilled in the art.

[0069] Fig. 1 shows an exemplary EV architecture 1.

[0070] In a charging mode of the EV architecture 1, a three-phase AC input 101 supplies power to an on-board charger 102, which in turn supplies power to a high-voltage powertrain battery 103, in which power is temporarily stored.

[0071] In a traction mode of the EV architecture 1, a three-phase inverter 104 utilizes energy stored in the powertrain battery 103 to supply power to an electric motor 105, which converts the power to torque applied to a drive shaft of the EV.

[0072] In both charging and traction modes, an auxiliary power module (APM) 106 utilizes energy stored in the powertrain battery 103 to convert high voltage to low voltage, e.g. 12V, and to supply power to a low-voltage auxiliary battery 107, in which power is temporarily stored. A control unit 108 of the powertrain of the EV utilizes energy stored in the auxiliary battery 107 to ensure its own operation.

[0073] The EV architecture shown for example in Fig. 1 relies on physically separated charging 102 and traction 104, 105 functions. The charging 102 function is always on-board the car, requires dedicated space, needs to be carried inside the car while the car is driving, and cannot provide any additional functions.

[0074] As will be explained below, the present disclosure aims at combining charging and traction functions, whether for single-phase or three-phase charging operation.

[0075] Figure 2 An arrangement 2 is shown according to an example of the present disclosure for single-phase charging.

[0076] The arrangement 2 comprises a power converter 201, an electric motor 203 and a power switch 205.

[0077] The power converter 201 comprises three branches 202, corresponding to three cells of the multi-cell power converter 201.

[0078] The electric motor 203 comprises three open-end stator windings 204, each having a first end and a second end.

[0079] As used herein, "open-end" can mean that the internal terminals of the motor 203 are available and reconfigurable.

[0080] Preferably, the motor 203 is an induction motor or a permanent magnet synchronous motor.

[0081] These configurations improve the customizability to various EV requirements.

[0082] The first ends of the stator windings 204 are connected to respective ones of the three branches 202 of the power converter 201, and the second ends of the stator windings 204 are connected together and have the same potential. The power switch 205 is used to selectively disconnect one of the second ends of the stator windings 204 from all other second ends to establish at most two different potentials. In other words, the power switch 205 can be open / cut-off, as shown in Figure 2 or can be closed / conducting. Depending on the state of the power switch 205, at most two different potentials can be established at the second ends of the stator windings 204. For charging purposes, the established potentials at the second ends of the stator windings 204 are connected to respective ones of the three branches 206 of a grid interface 207 connected to the arrangement 2.

[0083] In the example of Figure 2 , the power switch 205 is preferably used to disconnect one of the second ends of the stator windings 204 from all other second ends to establish two different potentials. That is, the power switch 205 is open / cut-off. The established two different potentials at the second ends of the stator windings 204 are connectable to respective ones of the three branches 206 of the grid interface 207.

[0084] This configuration enables the EV's charging mode to be connected to the single-phase power grid 208.

[0085] The power switch 205 can be placed between motor phases a and b, or between motor phases b and c. In other words, the operating principle of this arrangement does not change depending on the position of the switch. This also applies to the grid connection of motor 203, as all possible grid connection combinations are feasible in charging mode.

[0086] Preferably, the power converter 201 is used to regulate electrical parameters, such as voltage or current, on the demand side of the power converter 201. Nevertheless, the demand side actually depends on the operating mode of arrangement 2.

[0087] If arrangement 2 operates in charging mode, arrangement 2 attempts to satisfy energy storage 502 (not shown, see [link]). Figure 5 The demand side is the side that interfaces (or faces) the power converter 201 and the energy storage unit 502.

[0088] In contrast, if arrangement 2 operates in traction / drive mode, arrangement 2 attempts to meet the demands of motor 203 to generate the desired amount of torque. In this case, the demand side is the side where power converter 201 interfaces with motor 203.

[0089] This configuration enables bidirectional operation of the power converter 201 and the arrangement 2. Therefore, the arrangement 2 can charge the energy storage device 502, such as a battery, from the grid 208 and use the stored electricity to generate torque. Furthermore, if needed, the arrangement 2 can even return the stored electricity to the grid 208.

[0090] Figure 3 An arrangement 2 is shown as an example of this disclosure for three-phase charging.

[0091] Figure 3 Arrangement 2 corresponds to Figure 2 The embodiments are merely... Figure 3 Arrangement 2 also includes an inductor 301 having a first terminal and a second terminal. The first terminal of inductor 301 is connected to another branch of power converter 201, which corresponds to the fourth unit of multi-unit power converter 201; and the second terminal of inductor 301 can be connected to another branch of power grid interface 207.

[0092] To avoid generation of torque in the electric machine 203, one of the three stator windings 204 is disconnected from the common point by opening the power switch 205. The decoupled stator winding 204 is then connected to a branch 206 of the grid interface 207. The second branch 206 of the grid interface 207 is connected to the remaining two stator windings 204, where the phase currents are equally distributed between them. This way, the electric machine 203 does not generate torque during charging. The third and last branch 206 of the grid interface 207 is connected to the inductor 301, which in turn is connected to the other / fourth branch of the power converter 201.

[0093] This configuration enables the connection of the charging mode of the EV to the three-phase grid 208 without generating any torque and makes use of all the power electronics already existing for the traction system and the electric machine inductances. This saves space and improves power density, efficiency, and reliability.

[0094] Preferably, the inductor 301 has the same inductance as the stator windings 204, although the arrangement 2 is configured to work in a suboptimal way depending on the case with any inductance value of the inductor 301. In the fault-tolerant traction mode (see below Figure 6 ), the lower inductance as stator windings 204 can improve operation by extending the torque and speed limits. In the single-phase charging mode (see below Figure 4 ), the higher inductance as stator windings 204 will result in a reduction of the harmonic distortion of the grid currents. On the other hand, in the three-phase charging mode (see Figure 3 ), a different inductance than the stator windings 204 can result in an unbalanced current harmonic distortion between the grid currents.

[0095] Therefore, in view of the different operating modes of the arrangement, an inductance equal to the inductance of the stator windings 204 provides a reasonable trade-off.

[0096] Figure 4 An arrangement 2 according to another example of the present disclosure for single-phase charging is shown.

[0097] Figure 4 The arrangement 2 of Figure 3 corresponds to the embodiment of Figure 4 , except that in the arrangement 2 of the power switches 205 are used to not disconnect any of the second ends of the stator windings 204 from all the other second ends to establish a single potential. In other words, the power switches 205 are closed / conductive, and the machine windings 204 are connected in the traction mode.

[0098] The established single potential of the second end of the stator winding 204 is connected to one of the respective branches 206 of the grid interface 207. At the input of the grid interface 207, the single-phase grid 208 is connected. That is, the common connection point of the electric machine 203 is connected to one terminal of the alternating current grid 208 via the grid interface 207.

[0099] In this way, the grid current is distributed evenly between the electric machine windings 204 and no torque is generated. The second and last terminal of the single-phase alternating current grid 208 is connected to the inductor 301, which is then connected to the other / fourth branch of the power converter 201.

[0100] This configuration enables another charging mode with the connection of the single-phase grid 208.

[0101] Figure 5 An arrangement 2 according to an example of the present disclosure for torque, i.e. drive, generation is shown.

[0102] The energy storage interface 501 is connected to the power converter 201 of the arrangement 2 via a multi-wire connection, and the energy storage 502 is connected to the energy storage interface 501.

[0103] There is no limitation to the type of the energy storage 502, nor to its electrical rating (voltage and current).

[0104] The main purpose of the energy storage interface 501 is to provide the necessary functionality to interface the energy storage 502 and the power converter 201.

[0105] If the power converter 201 utilizes the energy stored in the energy storage 103 to power the electric machine 203 via the energy storage interface 501, torque or traction force is generated while the power switch 205 is on. In other words, the power switch 205 is closed to allow the electric machine windings 204 to be in a so-called "star configuration".

[0106] The established single potential of the second end of the stator winding 204, i.e. the neutral point of the electric machine 203, is not connected to any of the respective branches of the grid interface 207 (not shown).

[0107] In this configuration, the three branches 202 of the power converter 201 are used to control the current provided to the electric machine 203 in order to provide the torque required by the control unit of the EV. This configuration does not involve the fourth branch of the power converter 201 and the inductor 301. However, it is evident that torque generation is also possible in embodiments of the arrangement 2 involving the inductor 301.

[0108] This configuration enables the traction mode of the EV.

[0109] Preferably, the power converter 201 can operate according to a direct torque control (DTC), a field oriented control (FOC), a model predictive control (MPC) or an open loop control strategy and is configured to adjust the torque of the electric motor 203 according to a torque reference.

[0110] In the charging mode, the regulation target can comprise a DC-link voltage regulation or a DC-link current regulation.

[0111] These configurations increase the customizability to various EV requirements.

[0112] Figure 6 An arrangement 2 according to an example for torque generation with additional fault tolerance is shown.

[0113] Figure 6 The arrangement 2 of Figure 5 corresponds to the embodiment of Figure 6 The arrangement 2 of further comprises a further power switch 601 for connecting the second end of the inductor 301 to the established single potential of the second end of the stator winding 204.

[0114] This configuration extends the possibilities of connection in traction mode. By connecting the neutral point of the electric machine to the inductor 301, a reduction of common mode (CM) currents can be achieved, as well as fault tolerance.

[0115] Figure 7 An arrangement 2 according to an example of the present disclosure comprising an AC / AC power converter 201 is shown.

[0116] Figure 7 The power converter 201 of is configured to perform AC / AC power conversion. To this end, the first end of the stator winding 204 can be connected to a respective branch 202 of the AC side of the power converter 201.

[0117] Figure 5 As shown in Figure 6 , an energy storage interface 501 is connected to the AC / AC power converter 201 and an energy storage 502 is connected to the energy storage interface 501. Since the energy storage 502 is a DC device, e.g. a high voltage powertrain battery, the energy storage interface 501 is configured to mediate between the energy storage 502 and the AC / AC power converter 201. In other words, the energy storage interface 501 is for AC / DC devices, as shown in Figure 7 .

[0118] Figure 8An arrangement 2 is shown as an example of the present disclosure, including an AC / DC power converter 201.

[0119] Figure 8 Arrangement 2 corresponds to Figure 7 The embodiments are only in Figure 8 In arrangement 2, power converter 201 is used to perform AC / DC power conversion. For this purpose, the first end of stator winding 204 can be connected to the respective branch 202 on the AC side of power converter 201.

[0120] exist Figure 8 In this embodiment, the energy storage interface 501 is used to mediate between the energy storage 502, which is a DC device, and the DC side of the AC / DC power converter 201. In other words, the energy storage interface 501 is a DC / DC device, such as... Figure 7 As shown.

[0121] If the energy storage 502 and the AC / DC power converter 201 are matched in terms of DC voltage, the energy storage interface 501 can be omitted.

[0122] Figure 7 and Figure 8 The configuration enhances the customizability for various EV needs.

[0123] Figure 9 A general configuration of a power converter 201 according to an example arrangement 2 of this disclosure is shown.

[0124] Figure 9 The lower part schematically shows the power converter 201 comprising a parallel connection of four (generally: at least three) independently controlled half-bridges 901 on the same track. These half-bridges 901 expose / provide their respective branches 202 of the power converter 201.

[0125] This configuration enables a modular, multi-unit architecture for the power converter.

[0126] Each of the independently controlled half-bridge 901s is used to convert DC voltage to AC voltage by alternating between various DC voltage levels. The resulting AC voltage is non-sinusoidal, but designed to be as close as possible to a sinusoidal AC voltage.

[0127] For example, the power converter 201 may include a parallel connection of four (i.e., at least three) independently controlled two-level (2L) half-bridges 901A, such as Figure 9 The left side of the middle section is shown. This 2L half-bridge 901A may include a series connection of power switches.

[0128] This 2L half-bridge-based configuration is used, for example, in +V 直流 / 2 and -V直流 These two DC voltage levels are alternated, which means low circuit complexity. The 2L half-bridge is particularly suitable for medium voltage applications.

[0129] Alternatively, the power converter 201 can comprise a parallel connection of four (i.e. at least three) independently controlled n-level (nL) half-bridges 901A-901C, where the number n of DC voltage levels exceeds 2. Various three-level (3L) half-bridges 901A-901C are shown in Figure 9 on the right side of the middle part of

[0130] This 3L half-bridge based configuration is used to alternate between e.g. +V 直流 / 2, 0 and -V 直流 / 2. The additional zero voltage level reduces the losses and stress of the switching elements. Thus, the 3L half-bridge is particularly suitable for high voltage applications.

[0131] As a first example, a 3L-NPC (neutral point clamped) half-bridge 901B can comprise a 2L half-bridge as described above, in parallel with a series connection of diodes for clamping the neutral point, where the parallel connection is closed by an additional power switch in series.

[0132] As a second example, a 3L-ANPC (active neutral point clamped) half-bridge 901C can comprise two 2L half-bridges as described above in parallel, where the parallel connection is closed by an additional power switch in series.

[0133] This 3L-ANPC half-bridge 901C based configuration can “force” switching losses to occur on specific power switches of the half-bridge, thereby improving the overall efficiency.

[0134] As a third example, a 3L-FC (flying capacitor) half-bridge 901D can comprise a 2L half-bridge as described above, in parallel with a flying capacitor, where the parallel connection is closed by an additional power switch in series.

[0135] In particular, for all three-level configurations, the number n of levels can be extended from 3 to N.

[0136] Each of the above described independently controlled half-bridges 901 can in turn be composed of independently controlled half-bridges connected in parallel (aimed at dividing the output current of the half-bridge 901).

[0137] In the upper part of Figure 9 , it is pointed out that the power switches forming the above described half-bridges 901 can comprise bipolar transistors or field effect transistors (FETs).

[0138] Figure 10A general scheme is shown according to examples of the disclosure that can be connected to a grid interface 207 of an arrangement 2.

[0139] Figure 10 The arrangement 2 can be connected to a grid interface 207 that preferably comprises an electromagnetic interference (EMI) filter 1001 and a full pole grid disconnection switch 1002 that exposes / provides respective branches 206 of the grid interface 207.

[0140] This configuration improves EMI suppression and improves operational safety in EV charging mode.

[0141] Figure 11 A system is shown according to embodiments of the disclosure.

[0142] According to the first aspect of the disclosure or any of its embodiments, the system comprises an arrangement 2; a grid interface 207 connected to an electric machine 203 of the arrangement 2, an energy storage interface 501 connected to a power converter 201 of the arrangement 2, and an energy storage 502 connected to the energy storage interface 501.

[0143] Figure 11 The system enables replacement of the respective arrangement of Fig. 1 consisting of an on-board charger 102, a powertrain battery 103, a three-phase inverter 104 and an electric motor 105.

[0144] The comparison of Figs. 1 and 11 reveals that the on-board charger 102 of Fig. 1 is incorporated in the fourth unit of the electric machine 203, the inductor 301 and the power converter 201 as shown in Fig. 11. Figure 11

[0145] The system enables charging of an energy storage, e.g. a battery, of an EV from a grid, using stored electrical energy to generate torque, and even returning stored electrical energy to the grid if needed.

[0146] Figure 12 A flowchart of a method 12 according to examples of the disclosure that operates an arrangement 2 is shown.

[0147] The method 12 is for operating an arrangement 2 for power conversion and electric drive, which comprises a power converter 201, an electric machine 203 and a power switch 205. The power converter 201 comprises three branches 202 corresponding to three units of a multi-unit power converter 201. The electric machine comprises three open-end stator windings 204 having a first end and a second end, respectively. The second ends of the stator windings 204 are connected together and have the same electrical potential. The power switch 205 is used to selectively disconnect one of the second ends of the stator windings 204 from a star configuration to establish at most two different electrical potentials.

[0148] ​The method 12 comprises connecting 1201, selectively disconnecting 1202 and connecting 1203 steps:

[0149] The first step involves connecting 1201 the first ends of the stator windings 204 to respective ones of the three branches 202 of the power converter 201.

[0150] The second step involves selectively disconnecting 1202 one of the second ends of the stator windings 204 from all other second ends to establish at most two different potentials.

[0151] The third step involves connecting 1203 the established at most two different potentials of the second ends of the stator windings 204 to respective ones of the grid interface 207 of the arrangement 2.

[0152] This enables connection of the charging mode of the EV to the three-phase grid without generating any torque and with the use of all power electronics already existing for the traction system and the motor inductances. This saves space and improves power density, efficiency and reliability.

[0153] Preferably, the method 12 comprises the use of the arrangement 2 according to the first aspect or any one of its embodiments.

[0154] Hence, the above-mentioned device features and related advantages also apply by analogy in connection with the method according to the third aspect.

[0155] The processor or processing circuitry of the arrangement 2 can comprise hardware and / or the processing circuitry can be controlled by software. The hardware can comprise analog circuitry or digital circuitry, or both analog circuitry and digital circuitry. The digital circuitry can comprise components such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), or multi-purpose processors like microprocessors, etc.

[0156] The arrangement 2 can further comprise a memory circuitry storing one or more instructions executable by the processor or processing circuitry, in particular under control of software. For example, the memory circuitry can comprise a computer program (not shown) comprising program code for performing the method 12 according to the third aspect or any one of its embodiments when implemented on the processor of the arrangement 2 according to the first aspect or any one of its embodiments.

[0157] The present disclosure has been described in connection with various embodiments and implementations as examples. However, the skilled person will understand and appreciate that other variations are possible in the light of the present disclosure, the drawings, the claims and the independent inventive subject matter. In the claims and the description, the term "comprising" does not exclude other elements or steps, and the term "a" or "an" does not exclude a plurality. A single element or other unit can fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. A device (2) for power conversion and electric drive, said device (2) comprising: The power converter (201) includes three branches (202); The electric motor (203) includes three open-end stator windings (204), each having a first end and a second end; Power switch (205); The first end of the stator winding (204) is connected to the respective branch of the three branches (202) of the power converter (201); The second ends of the stator windings (204) are connected together and have the same potential; The power switch (205) is used to selectively disconnect one of the second terminals of the stator winding (204) from all the other second terminals to establish at most two different potentials; as well as The established at most two different potentials at the second end of the stator winding (204) are connected to the respective branches (206) of the power grid interface (207) connected to the device (2).

2. The apparatus (2) according to claim 1, further comprising: An inductor (301) has a first terminal and a second terminal; The first terminal of the inductor (301) is connected to another branch of the power converter (201); and The second end of the inductor (301) is connected to another branch of the power grid interface (207).

3. The apparatus (2) according to claim 2, The inductor (301) has the same inductance as the stator winding (204).

4. The apparatus (2) according to claim 1 above, The power switch (205) is used to disconnect one of the second terminals of the stator winding (204) from all the other second terminals to establish two different potentials; The two established different potentials at the second end of the stator winding (204) can be connected to the respective branches (206) of the power grid interface (207).

5. The apparatus (2) according to claim 2, The power switch (205) is used to prevent one of the second terminals of the stator winding (204) from being disconnected from all the other second terminals to establish a single potential.

6. The apparatus (2) according to claim 5, The established single potential at the second end of the stator winding (204) can be connected to one of the respective branches (206) of the power grid interface (207).

7. The apparatus (2) according to claim 1, The power converter (201) is used to adjust electrical parameters on the demand side of the power converter (201).

8. The apparatus (2) according to claim 5, The established single potential at the second end of the stator winding (204) is not connected to the respective branch (206) of the power grid interface (207).

9. The apparatus (2) according to claim 8, The power converter (201) can operate according to a direct torque control (DTC), field-oriented control (FOC), model predictive control (MPC), or open-loop control strategy, and is used to regulate the torque of the motor (203) according to a torque reference.

10. The apparatus (2) according to claim 8, further comprising: Another power switch (601) is used to connect the second terminal of the inductor (301) to the established single potential of the second terminal of the stator winding (204).

11. The apparatus (2) according to claim 1, The power converter (201) is used to perform AC / AC power conversion; The first end of the stator winding (204) is connected to the respective branch (202) on the AC side of the power converter (201).

12. The apparatus (2) according to claim 1, The power converter (201) is used to perform AC / DC power conversion; The first end of the stator winding (204) is connected to the respective branch (202) on the AC side of the power converter (201).

13. The apparatus (2) according to claim 1 above, The power converter (201) includes a parallel connection of at least three independently controlled half-bridges (901) providing the respective branches (202) of the power converter (201).

14. The apparatus (2) according to claim 13, The power converter (201) includes at least three independently controlled two-level 2L half-bridges (901A) connected in parallel.

15. The apparatus (2) according to claim 13, The power converter (201) includes at least three independently controlled n-level nL half-bridges (901A; 901B; 901C) connected in parallel, wherein the number of levels n exceeds 2.

16. The apparatus (2) according to claim 1, The device (2) can be connected to the power grid interface (207) and includes an electromagnetic interference (EMI) filter (1001) and an all-pole power grid disconnect switch (1002) to provide the respective branches (206) of the power grid interface (207).

17. The apparatus (2) according to any one of claims 1 to 16, The motor (203) is an induction motor or a permanent magnet synchronous motor.

18. A system for power conversion and electric drive, comprising: The apparatus (2) according to any one of claims 1 to 17, The power grid interface (207) is connected to the motor (203) of the device (2). Energy storage interface (501), connected to the power converter (201) of the device (2), and An energy storage device (502) is connected to the energy storage interface (501).

19. A method (12) for operating a device (2) for power conversion and electric drive, The device (2) includes: The power converter (201) includes three branches (202); The electric motor (203) includes three open-end stator windings (204), each having a first end and a second end; Power switch (205); The second ends of the stator windings (204) are connected together and have the same potential; as well as The power switch (205) is used to selectively disconnect one of the second terminals of the stator winding (204) from the star configuration to establish up to two different potentials; The method (12) includes: Connect the first end of the stator winding (204) of the stator winding (1201) to the respective branch (202) of the three branches (202) of the power converter (201); Selectively disconnect one of the second terminals of the stator winding (204) from all the other second terminals (1202) to establish at most two different potentials; as well as The established at most two different potentials of the second end of the stator winding (204) connected (1203) are connected to the respective branches (206) of the power grid interface (207) connected to the device (2).

20. A computer program product comprising, when implemented on a processor of the apparatus (2) of any one of claims 1 to 17, program code for performing the method (12) of claim 19.

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