Vehicle electrical system

Abstract

A vehicle electrical system comprises an electrical storage system (6), a first multiphase electric machine (5a) having a plurality of stator windings (8), a first converter (9a) connected to the electrical storage system (6) and to the first multiphase electric machine (5a), wherein the first converter (9a) has a plurality of switch arms (10, 11, 12) with switches (10a, 10b, 11a, 11b, 12a, 12b). The vehicle electrical system further comprises a second multiphase electric machine (5b) having a plurality of stator windings (13), a second converter (9b) connected to the electrical storage system (6) and to the second multiphase electric machine (5b), wherein the second converter (9b) has a plurality of switch arms (14, 15, 16) with switches (14a, 14b). The vehicle electrical system also includes a terminal (7) having multiple poles and configured to receive single-phase AC or multi-phase AC or DC from a charging power source (17) external to the vehicle, a first conductive line (18) connecting a first pole of the terminal (7) to a first switch arm (10) of a first converter (9a), a second conductive line (19) connecting a second pole of the terminal (7) to a first switch arm (14) of a second converter (9b), and a first inductor (20) arranged on one of the first conductive line (18) and the second conductive line (19). Finally, the vehicle electrical system further comprises a control system (21) operatively coupled to the first converter (9a) and the second converter (9b) and configured to control the operation of switches of the first converter (9a) and the second converter (9b) for preventing charging current from passing through any of the stator windings (8, 13) of the first multiphase electric machine (5a) and the second multiphase electric machine (5b) during the transfer of charge from the vehicle external charging power source (17) to the electrical storage system (6). The present disclosure also relates to a corresponding method for charging the electrical storage system (6) of the vehicle electrical system.

Description

Technical Field

[0001] The present disclosure relates to a vehicle electrical system and a method for charging an electrical storage system of a vehicle electrical system.

[0002] The vehicle electrical system and related methods according to the present disclosure may be implemented in a vehicle such as an electric vehicle or a hybrid vehicle. However, the vehicle electrical system and related methods according to the present disclosure are not limited to this particular vehicle, but may optionally also be installed or implemented in another type of vehicle, such as a truck, bus, rail vehicle, flying vehicle, marine vessel, off-road vehicle, mining vehicle, agricultural vehicle, work vehicle (such as a wheel loader or excavator), forest vehicle (such as a harvester or a truck), motorcycle, etc. Background Art

[0003] In the field of vehicle electrical systems, in particular electrical systems for plug-in electric vehicles, there is a constant need to further improve performance, operating life and cost-effectiveness.

[0004] For example, document US 2015 / 0231978A1 discloses an electrical system for charging a battery of a plug-in vehicle having dual motors and dual converters, wherein the converter is used to charge the battery and wherein the charging current is alternated between the first and second motors to prevent the motors from rotating during charge transfer.

[0005] However, despite some activity in this area, there is still a need for further improvements in vehicle electrical systems, particularly in terms of improving performance, operating life and cost-effectiveness. Summary of the invention

[0006] The object of the present disclosure is to provide a vehicle electrical system and a method for charging an electrical storage system of a vehicle electrical system which avoid the aforementioned problems. This object is achieved at least in part by the features of the independent claims.

[0007] According to a first aspect of the present disclosure, a vehicle electrical system is provided, the vehicle electrical system comprising an electrical storage system, a first multi-phase electric machine having a plurality of stator windings, a first converter connected to the electrical storage system and to the first multi-phase electric machine, wherein the first converter has a plurality of switch arms with switches, a second multi-phase electric machine having a plurality of stator windings, a second converter connected to the electrical storage system and to the second multi-phase electric machine, wherein the second converter has a plurality of switch arms with switches, has a plurality of poles and is configured to receive single-phase AC (single-phase alternating current) or multi-phase AC (multi-phase alternating current) from a charging power source external to the vehicle. A terminal for transmitting alternating current (alternating current) or DC (direct current), a first conductive line connecting the first pole of the terminal to the first switching arm of the first converter, a second conductive line connecting the second pole of the terminal to the first switching arm of the second converter, a first inductor arranged on one of the first conductive line and the second conductive line, and a control system, which is operatively connected to the first converter and the second converter and is configured to control the operation of the switches of the first converter and the second converter to prevent charging current from passing through any of the stator windings of the first multi-phase electric machine and the second multi-phase electric machine during the transfer of charge from a charging power source external to the vehicle to the electrical storage system.

[0008] According to a second aspect of the present disclosure, a method for charging an electrical storage system of a vehicle electrical system is provided. The method includes the following steps: connecting a first converter to a first multiphase electric machine having a plurality of stator windings and to the electrical storage system, wherein the first converter has a plurality of switch arms with switches; connecting a second converter to a second multiphase electric machine having a plurality of stator windings and to the electrical storage system, wherein the second converter has a plurality of switch arms with switches; connecting a first pole of a terminal to a first switch arm of the first converter through a first conductive line; connecting a second pole of the terminal to a first switch arm of the second converter through a second conductive line; providing a first inductor on one of the first conductive line and the second conductive line; connecting the terminal having a plurality of poles to a vehicle external charging power source configured to supply single-phase AC or multi-phase AC or DC; and controlling the operation of the switches of the first converter and the second converter to prevent charging current from passing through any of the stator windings of the first multiphase electric machine and the second multiphase electric machine during the transfer of charge from the vehicle external charging power source to the electrical storage system.

[0009] In this way, i.e., by controlling the operation of the switches of the converter for preventing the charging current from passing through the stator winding of the electric machine during charging, the risk of motor movement, motor vibration, energy loss and torque pulsation caused by the current flowing through the stator winding is eliminated or at least further reduced, thereby reducing noise, vibration or even movement of the motor / vehicle. In addition, by relying on the inductor arranged in the first conductive line or the second conductive line, the operation of the electrical system in the boost mode (i.e., boost mode) or the buck mode (i.e., decompression mode) is simplified, because only by selecting an appropriate inductor element, such as a coil, and installing it in the first conductive line and / or the second conductive line, a suitable and sufficiently large inductance in Henry (H) of the decompression / boost circuit inductor can be easily obtained. In addition, the size of the inductor can also be selected according to the stator winding design of the electric machine. Therefore, an electric machine with a relatively small inductance can be used in a vehicle circuit without negatively affecting the filtering, boost and / or buck operation performance. Finally, the dual purpose of the existing converter, i.e. both for conventional control of the speed and / or torque of the associated electric machine and for use as a rectifier of the AC charging current during charging of the electrical storage system, enables a more cost-effective design since the use of a separate on-board charger with an integrated rectifier can be avoided.

[0010] Further advantages are achieved by implementing one or several of the features of the dependent claims.

[0011] In some exemplary embodiments, when the control system is configured to charge the electrical storage system using electrical energy provided from a charging power source external to the vehicle in a voltage boost mode, the control system is configured to operate the first switch of the first switching arm of the first converter in alternating on-off cycles, so that the charging current during the on-cycle flows from the charging power source external to the vehicle, through the first conductive line, the first switch of the first switching arm of the first converter, an intrinsic reverse diode or an extrinsic reverse diode associated with the first switch of the first switching arm of the second converter, the second conductive line, the first inductor, and returns to the charging power source external to the vehicle while bypassing the electrical storage system, and the charging current during the off-cycle flows from the negative electrode of the electrical storage system, through the intrinsic reverse diode or the extrinsic reverse diode associated with the first switch of the first switching arm of the second converter, the second conductive line, the first inductor, the charging power source external to the vehicle, the first conductive line, the intrinsic reverse diode or the extrinsic reverse diode associated with the second switch of the first switching arm of the first converter, and flows to the positive electrode of the electrical storage system. Operation of the vehicle electrical system in the voltage boost mode allows the system to be more flexible with respect to charging voltage levels.

[0012] In some exemplary embodiments, when the vehicle external charging power source is AC for charging the electrical storage system in a voltage boost mode, the control system selectively controls the operation of the first switch arm of the first converter and the first switch arm of the second converter so that the current flow alternates between the following two states: during the first supply voltage polarity state, the current flows through the first switch of the first switch arm of the first converter for charging the electrical storage system, and during the second supply voltage polarity state, the current flows through the first switch of the first switch arm of the second converter for charging the electrical storage system. Therefore, both the positive and negative polarity phases of the AC power source can be used for effective charging of the vehicle electrical system.

[0013] In some exemplary embodiments, the vehicle electrical system further comprises: a first power switch arranged on one of the first conductive line and the second conductive line and configured to selectively open and close the first conductive line or the second conductive line; and a buck switch operatively connected to the first conductive line and the second conductive line and configured to selectively open and close the connection between the first conductive line or the second conductive line, wherein the first power switch, the buck switch and the first inductor are arranged to allow current to flow between a portion of the first conductive line and a portion of the second conductive line via the buck switch and the first inductor when the first power switch is in an open state. The possibility of operating the vehicle electrical system in a voltage buck mode makes the system more flexible in terms of charging voltage levels.

[0014] In some exemplary embodiments, the control system is operatively coupled to the first power switch and the buck switch and is configured to control their operation. It is generally desirable to perform a certain degree of joint (cooperative) control of the converter, the power switch, and the buck switch. Therefore, by having the control system also control the operation of the power switch and the buck switch, a more cost-effective system is achieved.

[0015] In some exemplary embodiments, when the control system is configured to charge the electrical storage system in the voltage step-down mode using the electric energy provided from the charging power source external to the vehicle, the control system is configured to synchronize and operate the first power switch and the step-down switch with alternating on-off cycles, thereby achieving a direct and easy-to-implement step-down solution that can also be implemented without changing or customizing the converter and / or the electric machine.

[0016] In some exemplary embodiments, when the control system is configured to charge the electric storage system using electric energy provided from a charging power source external to the vehicle in the voltage step-down mode, the control system is configured to set the first power switch to a closed state when the step-down switch is set to an open state, and to set the first power switch to an open state when the step-down switch is set to a closed state. Thus, a direct and easy-to-implement step-down solution is achieved, which can also be implemented without changing or customizing the converter and / or the electric machine.

[0017] In some exemplary embodiments, when the control system is configured to charge the electric storage system in the voltage step-down mode using the electric energy provided from the charging power source external to the vehicle, the control system is configured to keep all switches of the first converter and the second converter in the off state, thereby achieving a direct and easy-to-implement voltage step-down solution that can also be implemented without changing or customizing the converter and / or the electric machine.

[0018] In some exemplary embodiments, when the control system is configured to charge the electric storage system using electric energy supplied from the vehicle external charging power source in the voltage step-down mode, the control system is configured to be able to operate the first power switch and the step-down switch so that the charging current during the power switch on period flows from the negative electrode of the electric storage system through the intrinsic reverse diode or the non-intrinsic reverse diode associated with the first switch of the first switching arm of the second converter, the second conductive line, the first inductor, the vehicle external charging power source, the first conductive line, the intrinsic reverse diode or the non-intrinsic reverse diode associated with the second switch of the first switching arm of the first converter, to the positive electrode of the electric storage system. Thus, a direct and easy-to-implement step-down solution is achieved, which can also be implemented without changing the design or structure of the converter and / or the electric machine or customizing them.

[0019] In some exemplary embodiments, when the control system is configured to charge the electric storage system in the voltage step-down mode using the electric energy provided from the charging power source external to the vehicle, the control system is configured to be able to operate the first power switch and the step-down switch so that the charging current during the on-period of the step-down switch flows from the negative electrode of the electric storage system through the intrinsic reverse diode or the non-intrinsic reverse diode associated with the first switch of the first switching arm of the second converter, the second conductive line, the first inductor, the step-down switch, the first conductive line, the intrinsic reverse diode or the non-intrinsic reverse diode associated with the second switch of the first switching arm of the first converter, and flows to the positive electrode of the electric storage system. Thus, a direct and easy-to-implement step-down solution is achieved, which can also be implemented without changing the design or structure of the converter and / or the electric machine or customizing them.

[0020] In some exemplary embodiments, when the control system is configured to charge the electrical storage system in the voltage step-down mode using AC power provided from a charging power source external to the vehicle, the control system is configured to be able to operate the first power switch and the step-down switch so that the charging current alternates between the following two states: flowing through an intrinsic reverse diode or an extrinsic reverse diode associated with the second switch of the first switching arm of the first converter and an intrinsic reverse diode or an extrinsic reverse diode associated with the first switch of the first switching arm of the second converter for charging the electrical storage system during the first supply voltage polarity state; and flowing through an intrinsic reverse diode or an extrinsic reverse diode associated with the second switch of the first switching arm of the second converter and an intrinsic reverse diode or an extrinsic reverse diode associated with the first switch of the first switching arm of the first converter for charging the electrical storage system during the second supply voltage polarity state. Thus, a direct and easy-to-implement step-down solution is achieved, which can also be implemented without changing or customizing the design or structure of the converter and / or the electric machine.

[0021] In some exemplary embodiments, when the control system is configured to charge the electrical storage system in a voltage boost mode using electrical energy provided from a charging power source external to the vehicle, the control system is configured to control the operation of the switches of the first converter and the second converter by operating the first switch of the first switching arm of the first converter in alternating on-off cycles, while controlling the other switches of the first converter and the second converter to remain in an off state, so as to prevent the charging current from passing through any of the stator windings of the first multi-phase electric machine and the second multi-phase electric machine.

[0022] In some exemplary embodiments, when the control system is configured to charge the electrical storage system in a voltage step-down mode using electrical energy provided from a charging power source external to the vehicle, the control system is configured to control the operation of the switches of the first converter and the second converter by keeping all switches of the first converter and the second converter in an off state to prevent the charging current from passing through any of the stator windings of the first multi-phase electric machine and the second multi-phase electric machine.

[0023] In some exemplary embodiments, the vehicle electrical system further comprises a third multi-phase electric machine having a plurality of stator windings, a third converter connected to the electrical storage system and to the third multi-phase electric machine, wherein the third converter has a plurality of switch arms with switches, a third conductive line connecting the third pole of the terminal with the first switch arm of the third converter, a second inductor arranged in the second conductive line, a third inductor arranged in the third conductive line, wherein the first inductor is arranged in the first conductive line, and wherein the control system is operatively coupled to each of the first converter, the second converter, and the third converter and is configured to control the operation of the switches of the first converter, the second converter, and the third converter to prevent charging current from passing through any of the stator windings of the first multi-phase electric machine, the second multi-phase electric machine, and the third multi-phase electric machine during three-phase charging of the electrical storage system from the vehicle external charging power source. The three-phase AC used to charge the electrical storage system is generally much faster and more powerful than single-phase AC.

[0024] In some exemplary embodiments, the first power switch and the step-down switch are located on a common circuit board separate from the first converter and the second converter. Thus, a more economical implementation of the vehicle electrical system can be achieved because no or only little modification of the converter and / or the electric machine is required.

[0025] In some exemplary embodiments, the terminal is configured to receive single-phase AC from a charging power source external to the vehicle, wherein the vehicle electrical system includes a first power switch and a second power switch, the first power switch is arranged in the first conductive line and is configured to selectively open and close the first conductive line, and the second power switch is arranged in the second conductive line and is configured to selectively open and close the second conductive line. Two power switches, one for the phase line of the single-phase AC and one for the neutral line of the single-phase AC, provide more safety measures to prevent accidental short circuits, etc.

[0026] Alternatively, in some exemplary embodiments, the terminal is configured to receive three-phase AC from a charging power source external to the vehicle, wherein the vehicle electrical system includes a first power switch, a second power switch, and a third power switch, the first power switch being arranged in the first conductive circuit and configured to selectively open and close the first conductive circuit, the second power switch being arranged in the second conductive circuit and configured to selectively open and close the second conductive circuit, and the third power switch being arranged in the third conductive circuit and configured to selectively open and close the third conductive circuit. The three power switches, each corresponding to one of the phases of the three-phase AC power source, provide more safety to prevent accidental short circuits, etc.

[0027] In some exemplary embodiments, the first conductive line is attached to the first switching arm or to a conductive line connecting the first switching arm with a stator winding of a first polyphase electric machine, and the second conductive line is attached to the second switching arm or to a conductive line connecting the second switching arm with a stator winding of a second polyphase electric machine.

[0028] In some exemplary embodiments, the first conductive line is connected to a first converter, or a first multi-phase electric machine, or an intermediate element operatively connecting the first converter to the first multi-phase electric machine, so that the charging current supplied via the first conductive line can reach the first converter without passing through the stator winding of the first multi-phase electric machine, and wherein the second conductive line is connected to a second converter, or a second multi-phase electric machine, or an intermediate element operatively connecting the second converter to the second multi-phase electric machine, so that the charging current supplied via the second conductive line can reach the second converter without passing through the stator winding of the second multi-phase electric machine.

[0029] In some exemplary embodiments, the first inductor is a separate element from the first polyphase electric machine and the second polyphase electric machine.

[0030] In some exemplary embodiments, the first conductive line is configured to be connected to a phase line of a single-phase AC power source, and the second conductive line is configured to be connected to a neutral line of the single-phase AC power source.

[0031] In some exemplary embodiments, the method further includes, when charging the electrical storage system in the voltage boost mode using electrical energy provided from a vehicle external charging power source, operating the first switch of the first switching arm of the first converter in alternating on-off cycles, such that the charging current during the on-cycle flows from the vehicle external charging power source through the first conductive line, the first switch of the first switching arm of the first converter, an intrinsic reverse diode or an extrinsic reverse diode associated with the first switch of the first switching arm of the second converter, the second conductive line, the first inductor, back to the vehicle external charging power source while bypassing the electrical storage system, and the charging current during the off-cycle flows from the negative electrode of the electrical storage system through the intrinsic reverse diode or an extrinsic reverse diode associated with the first switch of the first switching arm of the second converter, the second conductive line, the first inductor, the vehicle external charging power source, the first conductive line, the intrinsic reverse diode or an extrinsic reverse diode associated with the second switch of the first switching arm of the first converter, to the positive electrode of the electrical storage system. Operation of the vehicle electrical system in the boost mode provides a more flexible system and a wider range of applications.

[0032] In some exemplary embodiments, the method further includes: providing a first power switch on one of the first conductive line and the second conductive line and configured to selectively open and close the first conductive line or the second conductive line; and providing a buck switch operatively connected to the first conductive line and the second conductive line and configured to selectively open and close the connection between the first conductive line or the second conductive line, wherein the first power switch, the buck switch and the first inductor are arranged to allow current to flow between the first conductive line and the second conductive line via the buck switch and the first inductor when the first power switch is in an open state. The operation of the automotive electrical system in buck mode provides a more flexible system and a wider range of applications.

[0033] In some exemplary embodiments, the method further includes charging the electrical storage system in a voltage step-down mode using electrical energy provided from a charging power source external to the vehicle by operating a first power switch and a buck switch, such that a charging current during an on-period of the power switch flows from a negative electrode of the electrical storage system, through an intrinsic reverse diode or a non-intrinsic reverse diode associated with a first switch of a first switching arm of a second converter, a second conductive line, a first inductor, a charging power source external to the vehicle, a first conductive line, an intrinsic reverse diode or a non-intrinsic reverse diode associated with a second switch of a first switching arm of a first converter, to a positive electrode of the electrical storage system, and such that a charging current during an on-period of the buck switch flows from a negative electrode of the electrical storage system, through an intrinsic reverse diode or a non-intrinsic reverse diode associated with a first switch of a first switching arm of a second converter, a second conductive line, a first inductor, a charging power source external to the vehicle, a first conductive line, an intrinsic reverse diode or a non-intrinsic reverse diode associated with a second switch of a first switching arm of a first converter, to a positive electrode of the electrical storage system. Operation of the automotive electrical system in buck mode provides a more flexible system and a wider range of applications.

[0034] In some exemplary embodiments, the method further comprises charging the electrical storage system in a voltage step-down mode using electrical energy provided from a charging power source external to the vehicle by operating the first power switch and the step-down switch synchronously and in alternating on-off cycles. The operation of the automotive electrical system in the step-down mode provides a more flexible system and a wider range of applications.

[0035] In some exemplary embodiments, the method further comprises charging the electrical storage system using electric energy provided from a charging power source external to the vehicle in the voltage step-down mode by setting the first power switch to a closed state when the step-down switch is set to an open state, and vice versa. The operation of the automotive electrical system in the step-down mode provides a more flexible system and a wider range of applications.

[0036] In some exemplary embodiments, the method further comprises charging the electrical storage system in the voltage step-down mode using electrical energy provided from a charging power source external to the vehicle by keeping all switches of the first converter and the second converter in an off state. The operation of the automotive electrical system in the step-down mode provides a more flexible system and a wider range of applications.

[0037] In some exemplary embodiments, the method further includes supplying single-phase AC from a charging power source external to the vehicle, and controlling the operation of the first power switch and the buck switch so that the charging current in the voltage buck mode alternates between the following two states: flowing through an intrinsic reverse diode or a non-intrinsic reverse diode associated with the second switch of the first switching arm of the first converter and an intrinsic reverse diode or a non-intrinsic reverse diode associated with the first switch of the first switching arm of the second converter for charging the electrical storage system during the first supply voltage polarity state; and flowing through an intrinsic reverse diode or a non-intrinsic reverse diode associated with the second switch of the first switching arm of the second converter and an intrinsic reverse diode or a non-intrinsic reverse diode associated with the first switch of the first switching arm of the first converter for charging the electrical storage system during the second supply voltage polarity state. The operation of the automotive electrical system in the buck mode provides a more flexible system and a wider range of applications.

[0038] In some exemplary embodiments, the method further includes: charging the electrical storage system in a voltage boost mode using electrical energy provided from a charging power source external to the vehicle; controlling the operation of switches of the first converter and the second converter by operating the first switch of the first switching arm of the first converter in alternating on-off cycles, while controlling other switches of the first converter and the second converter to remain in an off state to prevent charging current from passing through any of the stator windings of the first multi-phase electric machine and the second multi-phase electric machine.

[0039] In some exemplary embodiments, the method further includes: charging the electrical storage system in a voltage step-down mode using electrical energy provided from a charging power source external to the vehicle; and controlling the operation of the switches of the first converter and the second converter by keeping all switches of the first converter and the second converter in an off state to prevent charging current from passing through any of the stator windings of the first multi-phase electric machine and the second multi-phase electric machine.

[0040] In some exemplary embodiments, the method also includes: connecting a third converter to a third multi-phase electric machine having multiple stator windings and to the electrical storage system, wherein the third converter has multiple switch arms with switches; connecting a third pole of the terminal to a first switch arm of the third converter via a third conductive line; providing the first inductor in the first conductive line; providing a second inductor in the second conductive line; providing a third inductor in the third conductive line; connecting the terminal having multiple poles to an external vehicle charging power source configured to supply three-phase AC; and controlling the operation of the switches of the first converter, the second converter, and the third converter to prevent charging current from passing through any of the stator windings of the first multi-phase electric machine, the second multi-phase electric machine, and the third multi-phase electric machine during the transfer of charge from the external vehicle charging power source to the electrical storage system.

[0041] A three-phase charging supply typically significantly increases charging speed and reduces the load on individual cables and fuses in the supply grid.

[0042] Other features and advantages of the present invention will become apparent when studying the attached claims and the following description. Those skilled in the art realize that different features of the present disclosure may be combined to create embodiments other than those explicitly described above and below, without departing from the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The present disclosure will be described in detail below with reference to the accompanying drawings, in which:

[0044] Figure 1 schematically shows a side view of a plug-in vehicle,

[0045] Figure 2 Schematically shows a first exemplary embodiment of a vehicle electrical system according to the present disclosure,

[0046] Figure 3a-3d Schematically shows the two polarities for a single-phase AC power supply, Figure 2 The function of the vehicle electrical system in boost mode,

[0047] Figure 4 Schematically shows another exemplary embodiment of a vehicle electrical system according to the present disclosure,

[0048] Figure 5a-5d Schematically shows the two polarities for a single-phase AC power supply, Figure 4 The function of the vehicle electrical system in buck mode,

[0049] Figure 6Schematically shows another exemplary embodiment of a vehicle electrical system according to the present disclosure,

[0050] Figure 7 Schematically illustrates yet another exemplary embodiment of a vehicle electrical system configured for charging with three-phase AC according to the present disclosure,

[0051] Figure 8 Schematically shows another exemplary embodiment of a vehicle electrical system according to the present disclosure,

[0052] Fig. 9 The basic method steps of a method for charging an electrical storage system are schematically shown. DETAILED DESCRIPTION

[0053] Various aspects of the present disclosure will be described below in conjunction with the accompanying drawings to illustrate rather than limit the present disclosure, wherein like reference numerals represent like elements, and variations of the described aspects are not limited to the specifically illustrated embodiments, but can be applied to other variations of the present disclosure.

[0054] A vehicle electrical system according to the present disclosure is configured to be implemented in a hybrid vehicle or a fully electric vehicle, such as an automobile.

[0055] Figure 1 A side view of a vehicle 1 of an example type that can be implemented with the vehicle electrical system is schematically shown. The electric vehicle 1 is shown here in the form of an automobile having front wheels 2a, rear wheels 2b, a passenger compartment 3, a luggage compartment 4 and a vehicle powertrain including at least two electric propulsion motors 5a, 5b, such as two multi-phase AC motors or two DC motors.

[0056] The vehicle powertrain 5 also includes an electrical storage system 6 for vehicle propulsion, such as a battery or a combination of a battery and a capacitor. If the electric vehicle is a plug-in vehicle, i.e. configured for charging the electrical storage system by electrical energy from an external grid, the vehicle may additionally include, for example, a terminal 7 configured for receiving an external charging connector for charging the electrical storage system. The terminal 7 may advantageously be accessible from the outside of the vehicle 1.

[0057] The vehicle powertrain 5 may additionally include, for example, an internal combustion engine or a fuel cell.

[0058] In conventional solutions, a separate on-board charger (OBC) is usually used to charge the vehicle's electrical storage system. A conventional OBC is usually connected to a terminal for connection to the power grid and is connected to the electrical storage system for charging the electrical storage system with power from the power grid, for example, during vehicle parking. The OBC usually includes a rectifier for providing AC / DC conversion of the supplied single-phase AC before charging the electrical storage system with DC. However, for an electrical system according to the present disclosure, the OBC can be omitted, and by also using the first converter 9a and the second converter 9b to charge the electrical storage system 6 using electrical energy from the power grid, i.e., electrical energy from a charging power source external to the vehicle, the first converter and the second converter, which are usually only used to power the electric machines 5a, 5b and the vehicle's brake regeneration, have dual functions here.

[0059] Therefore, reference is made to a first exemplary embodiment of a vehicle electrical system according to the present disclosure. Figure 2 The vehicle electrical system may include an on-board electrical storage system 6, a first multi-phase electric machine 5a having a plurality of stator windings 8, and a first converter 9a connected to the electrical storage system 6 and to the first multi-phase electric machine 5a, wherein the first converter 9a has a plurality of switch arms 10, 11, 12 with switches 10a, 10b, 11a, 11b, 12a, 12b.

[0060] The vehicle electrical system further comprises a second multiphase electric machine 5b having a plurality of stator windings 13, a second converter 9b connected to the electrical storage system 6 and to the second multiphase electric machine 5b, wherein the second converter 9b has a plurality of switch arms 14, 15, 16 with switches 14a, 14b.

[0061] The vehicle electrical system also includes a terminal 7 having multiple poles and configured to receive single-phase AC or multi-phase AC or DC from a vehicle external charging power source 17, a first conductive line 18 connecting a first pole of the terminal 7 to a first switching arm 10 of a first converter 9a, a second conductive line 19 connecting a second pole of the terminal 7 to a first switching arm 14 of a second converter 9b, and a first inductor 20 arranged on one of the first conductive line 18 and the second conductive line 19.

[0062] The vehicle electrical system also includes a control system 21, which is operatively connected to the first converter 9a and the second converter 9b and is configured to control the operation of switches of the first converter 9a and the second converter 9b so as to prevent charging current from passing through either of the stator windings 8, 13 of the first multi-phase electric machine 5a and the second multi-phase electric machine 5b during the transfer of charge from the vehicle external charging power source 17 to the electrical storage system 6.

[0063] Therefore, the first inductor 20 is a separate element from the first and second multi-phase electric machines 5a and 5b.

[0064] The electrical storage system 6 may include a high voltage battery composed of, for example, lithium-ion battery cells, lithium-sulfur battery cells, or solid-state battery cells. The high voltage battery may, for example, have a rated voltage level in the range of 100 V-1500 V. The battery capacity in kWh depends on factors such as whether the vehicle is a hybrid vehicle with an additional power source (e.g., an internal combustion engine), or whether the vehicle is a pure electric vehicle, and the desired operating range. The capacity may, for example, be about 10-150 kWh.

[0065] However, in certain applications, such as for example so-called “mild hybrid” systems, the electrical storage system 6 may comprise a battery nominal output voltage of, for example, about 24V-59V, in particular 24V or 48V.

[0066] The first polyphase electric machine 5a and the second polyphase electric machine 5b can be, for example, three-phase, five-phase or seven-phase electric machines, etc. For example, a three-phase electric machine can have three stator windings, each winding being divided into two halves and arranged on opposite sides in the stator. The three stator windings can then be arranged 120 degrees apart from each other, and each stator winding can then be considered to have two magnetic poles, i.e. a three-phase two-pole electric machine. However, the stator winding can also be alternatively divided into four parts, wherein each part is shifted 90 degrees apart from each other. Such a stator winding is considered to have four poles, i.e. a three-phase four-pole electric machine. Other stator winding arrangements are also possible, such as a six-pole arrangement, etc.

[0067] The first electric machine 5a and the second electric machine 5b may be, for example, permanent magnet synchronous motors or AC induction motors or switched reluctance motors.

[0068] In reference Figure 2 In the exemplary embodiment described, each of the first converter 9a and the second converter 9b has three switching arms, namely a first switching arm 10, 14, a second switching arm 11, 15 and a third switching arm 12, 16, which are all connected in parallel. Each of the switching arms 10, 11, 12, 14, 15, 16 of the first converter 9a and the second converter 9b is supplied with direct current from the electrical storage system 6, and the control system can then control the switches to perform appropriate switching operations of the converter switches 10a, 10b, 11a, 11b, 12a, 12b, 14a, 14b for providing the stator windings 8, 13 of the first electric machine 5a and the second electric machine 5b with a phase-shifted output voltage having a more or less three-phase sinusoidal operating characteristic.

[0069] Each switch leg 10, 11, 12, 14, 15, 16 may have two switches, for example a first switch 10a, 11a, 12a, 14a and a second switch 10b, 11b, 12b, 14b. The first stator winding 8, 13 of the first electric machine 5a and the second electric machine 5b may be connected to the first switch leg 10, 14 between the first switch 10a, 14a and the second switch 10b, 14b of the first converter 9a and the second converter 9b, respectively. Similarly, the second stator winding 8, 13 of the first electric machine 5a and the second electric machine 5b may be connected to the second switch leg 11, 15 between the first switch and the second switch 11a, 11b of the first converter 9a and the second converter 9b, respectively. Finally, the third stator winding 8, 13 of the first electric machine 5a and the second electric machine 5b may be connected to the third switch leg 12, 14 between the first switch and the second switch 12a, 12b of the first converter 9a and the second converter 9b, respectively.

[0070] However, other converter designs are possible within the scope of the present application.

[0071] The switches 10a, 10b, 11a, 11b, 12a, 12b, 14a, 14b may be, for example, power transistors for controlling torque and / or speed of the first and second multiphase electric machines. For example, the switches may be insulated gate bipolar transistors (IGBTs) or MOSFETs.

[0072] Each of the switches 10a, 10b, 11a, 11b, 12a, 12b, 14a, 14b of the first converter 9a and the second converter 9b is provided with a reverse diode 10c, 10d, 14c, 14d connected in parallel, also referred to as a freewheeling diode, a body diode or an absorption diode. The reverse diode can be, for example, an intrinsic diode, i.e., a reverse diode function. For example, a MOSTFET type transistor, due to its design and structure, generally includes an intrinsic reverse diode function. However, some IGBTs generally do not have such an intrinsic reverse diode, and can then be provided with a non-intrinsic reverse diode instead, i.e., a physically independent diode separated from the transistor and connected in parallel with the transistor. In addition, a MOSFET transistor can also be provided with a non-intrinsic reverse diode. A reverse diode is required to avoid a situation where a large negative voltage may accumulate on the transistor when switching an inductive load, because an inductive load generally generates a large negative voltage during a negative current change, which may damage the transistor.

[0073] For example, Figure 2As schematically shown in FIG. 1 , terminal 7 may have three poles, such as a phase pole, a neutral pole, and a ground pole, for providing a single-phase AC to the vehicle. For example, a first conductive line 18 may be connected to a phase pole of terminal 7, and a second conductive line 19 may be connected to a neutral pole of terminal 7. Some additional poles may be provided for communication between the vehicle external charging power source 17 and the vehicle electrical system. The grounding pole may be connected to a grounding point 22 of the vehicle, such as a metal chassis, etc. Alternatively, terminal 7 may, for example, have five poles, such as a first phase pole, a second phase pole, a third phase pole, a neutral pole, and a ground pole.

[0074] The first conductive path 18 and the second conductive path 19 for connecting the terminal 7 with the first transformer 9a and the second transformer 9b may consist of a single conductor or a plurality of interconnected conductors.

[0075] like Figure 2 As schematically shown in the figure, the control system 21 can, for example, consist of a single electronic control unit (ECU), or alternatively consist of a distributed control system having multiple interconnected control units, such as a first converter control unit and a second converter control unit, each converter control unit being controlled by a common powertrain control unit.

[0076] The control unit 21 is configured to control the operation of the switches 10a, 10b, 11a, 11b, 12a, 12b, 14a, 14b of the first converter 9a and the second converter 9b, so as to prevent the charging current from passing through any of the stator windings 8, 13 of the first multi-phase electric machine 5a and the second multi-phase electric machine 5b during the transfer of charge from the vehicle external charging power source 17 to the electrical storage system 6. This is achieved by appropriately opening and closing the first switches 10a, 14a of the switch arms 10, 14 connected to the first conductive line 18 and the second conductive line 19.

[0077] Although the control unit 21 is configured to control the operation of the switches 10a, 10b, 11a, 11b, 12a, 12b, 14a, 14b so as to prevent the charging current from passing through any of the stator windings 8, 13, under certain operating conditions, a relatively small charging current may actually still pass through some of the stator windings 8, 13. For example, during the time period of actual charging of the electrical storage system, i.e., when all the switches 10a, 10b, 11a, 11b, 12a, 12b, 14a, 14b of the converters 9a, 9b are in the off state, and the charging current delivered by the first conductive line or the second conductive line 18, 19 mainly passes through the reverse diodes 10d, 14c, 14d, 10c of the first switch leg 10, 14, a small current may simultaneously flow through the first conductive line or the second conductive line 18, 19 and through the stator winding of the first electric machine 5a, 5b, and through the reverse diodes of the second switch leg and / or the third switch leg of the converters 9a, 9b, depending on the polarity. However, due to the impedance of the stator winding, this small current is usually much smaller and is therefore considered to be virtually non-existent.

[0078] Therefore, by connecting one pole of a DC power supply or a single-phase AC power supply to the first switching arm of a first converter, and connecting the other pole of a DC power supply or a single-phase AC power supply to the first switching arm of a second converter, wherein both the first converter and the second converter are connected to a common on-board electrical storage system, charging of the common on-board electrical storage system can be accomplished without the charging current passing through the stator windings of the first electric machine and the second electric machine, while using the converter to both drive the motor and charge the on-board electrical storage system.

[0079] As described above, the first conductive line 18 connects the terminal 7 with the first switch leg 10 of the first converter 9a, and the second conductive line 19 connects the terminal 7 with the first switch leg 14 of the second converter 9b. In particular, the first conductive line 18 connects the terminal 7 with the first switch leg 10 of the first converter 9a at a position between the first switch 10a and the second switch 10b of the first switch leg 10 of the first converter 9a, and the second conductive line 19 connects the terminal 7 with the first switch leg 14 of the second converter 9b at a position between the first switch 10a and the second switch 14a, 14b of the first switch leg 14 of the second converter 9b.

[0080] In addition, the first conductive line 18 and the second conductive line 19 may be directly attached to the first switch arm 10, 14, respectively, or indirectly connected to the first switch arm 10, 14 through another conductor. In other words, the first conductive line 18 may be attached to the first switch arm 10 of the first converter 9a, or to the first conductive line 24 connecting the first switch arm 10 with the stator winding 8 of the first multi-phase electric machine 5a, and the second conductive line 19 may be attached to the first switch arm 14 of the second converter 9b, or to the second conductive line 25 connecting the first switch arm 14 with the stator winding 13 of the second multi-phase electric machine 5b.

[0081] In other words, the first conductive path 24 can be regarded as corresponding to an intermediate element that operatively connects the first switching arm 10 of the first converter 9a with the stator winding 8 of the first multi-phase electric machine 5a, and the second conductive path 25 can be regarded as corresponding to an intermediate element that operatively connects the first switching arm 14 of the second converter 9b with the stator winding 13 of the second multi-phase electric machine.

[0082] Furthermore, the first conductive path 18 can be connected to the first switch leg 10 or the first conductive path 24 at a first connection point 26 located outside the housing of the first converter 9a and outside the housing of the first motor 5a, because conventional, off-the-shelf converters can be used, thereby avoiding the need for custom design and thus reducing costs. The same applies to the second conductive path 19, which can be attached to the first switch leg 14 or the second conductive path 24 at a second connection point 27 located outside the housing of the second converter 9b and outside the housing of the second motor 5b.

[0083] The plurality of stator windings of each of the first motor 5a and the second motor 5b may be arranged, for example, in a star connection having a common neutral point 29, such as Figure 2 As shown, or arranged in a triangle connection, etc.

[0084] The external charging connector 23 is connected to a vehicle external charging power source 17 , ie, an external power grid 17 , such as a single-phase AC power source or a DC power source.

[0085] By means of a first inductor 20 arranged on one of the first conductive line 18 and the second conductive line 19, a voltage step-up conversion of the power supply voltage can be achieved. This is useful, for example, when the voltage level of the electrical storage system is higher than the peak voltage of the AC power supply or higher than the DC power supply voltage. For example, without voltage step-up conversion (also commonly referred to as boost conversion), it is impossible to charge a 400V battery from a 230V or 120V AC grid power supply. The voltage step-up conversion is achieved by combining the first inductor 20 with appropriate switch control of the switches of the first converter 9a and the second converter 9b, and combining, for example, appropriate pulse width modulation, etc., to obtain the desired charging voltage level.

[0086] The following will refer to Figure 3a to Figure 3d To illustrate the operation of the vehicle electrical system in voltage boost mode when connected to and powered by single-phase AC, Figure 3a shows the charging current path during the switch on period in the first supply voltage polarity state, Figure 3b shows the charging current path during the switch off period in the first supply voltage polarity state, Figure 3c shows the charging current path during the switch on period in the second supply voltage polarity state, and Figure 3d The charging current path during the switch off period in the second supply voltage polarity state is shown.

[0087] Specifically, refer to Figure 3a and Figure 3b When the control system 21 is configured to charge the electrical storage system 6 using electrical energy provided from the vehicle external charging power source 17 in the voltage boost mode, the control system 21 is configured to be able to operate the first switch 1a of the first switch arm 10 of the first converter 9a in alternating on-off cycles, so that the charging current during the on-cycle of the first switch 10a flows from the vehicle external charging power source 17 through the first conductive line 18 and the associated first inductor 20, the first switch 10a of the first switch arm 10 of the first converter 9a, the intrinsic reverse diode or the non-intrinsic reverse diode 14c associated with the first switch 14a of the first switch arm 14 of the second converter 9b, and the second conductive line 19, and returns to the vehicle external charging power source 17 while bypassing the electrical storage system 6.

[0088] The sequential order of the electrical components listed above is not exclusive and this order may be changed without departing from the disclosure defined by the independent claims. For example, the first inductor may alternatively be arranged within the second conductive trace 19. This applies to all embodiments described in the present disclosure.

[0089] During the on period, the first switch 10a is in a closed state, i.e., a conductive state, thereby causing the charging current flowing through the first inductor 20 to increase, so that energy begins to accumulate in the first inductor 20. In particular, when the current passing through the first inductor 20 rises slowly, an electromotive force (emf) is generated, which acts to oppose the increase in current. Therefore, in order to form a current in the first inductor 20, work must be done by the vehicle external charging power source 17 to oppose the electromotive force. The accumulated energy of the first inductor 20 is actually stored according to the enhanced magnetic field generated by the current flowing through the first inductor 20.

[0090] During the subsequent off cycle, the first switch 10a is in an off state, i.e., a non-conductive state. As a result, the charging voltage from the vehicle external charging power source 17 combines and cooperates with the energy stored in the first inductor 20 to increase the total available charging voltage to a voltage level exceeding the electrical storage system 6.

[0091] In particular, during the off-period, the first switch 10a is open and the only path provided for the current generated by the first inductor 20 is through the reverse diode 10d of the second switch 10b of the first converter 9a and the electrical storage system 6. This results in the energy accumulated during the on-period being transferred back into the circuit and the electrical storage system 6 as the current through the inductor 20 ramps up and its associated magnetic field collapses.

[0092] In other words, during the shutdown period, the charging current flows from the negative electrode of the electrical storage system 6, through the intrinsic reverse diode or the non-intrinsic reverse diode 14c associated with the first switch 14a of the first switching arm 14 of the second converter 9b, the second conductive line 19, the vehicle external charging power source 17, the first conductive line including the first inductor 20, the intrinsic reverse diode or the non-intrinsic reverse diode 10d associated with the second switch 10b of the first switching arm 10 of the first converter 9a, and flows to the positive electrode of the electrical storage system, thereby charging the electrical storage system 6.

[0093] The ratio between the on-period and the total period of the supply voltage polarity state, i.e. the fraction of the commutation period T during which the first switch is "on", is called the duty ratio and ranges between 0 (the first switch is never on) and 1 (the first switch is always on). Therefore, the control unit controls the pulse width modulation of the first switch 10a.

[0094] During operation in the boost mode, the charging voltage supplied to the electric storage system 6 is always higher than the input voltage at the vehicle external charging power source 17. Furthermore, as the duty cycle goes from 0 to 1, the level of the charging voltage supplied to the electric storage system 6 increases.

[0095] Obviously, the other switches of the first converter 9a and the second converter 9b should be controlled to remain in an off state during the above-mentioned boost mode.

[0096] Reference above Figure 3a and 3b The operating conditions of the vehicle electrical system described apply to the first supply voltage polarity state of the single-phase AC vehicle external charging power source 17, i.e., during a short time period when current flows in one direction of the alternating current provided by the vehicle external charging power source 17. For example, for a 50 Hz AC power source, this time period is 10 ms.

[0097] Refer to the following Figure 3c and 3d The operating conditions of the vehicle electrical system during the subsequent short period of time when the single-phase AC vehicle external charging power source 17 operates in the second supply voltage polarity state, ie, during the short period of time when the current temporarily changes direction and flows in the opposite direction, are described in more detail.

[0098] Specifically, the control system 21 is configured to charge the electrical storage system 6 using the electric energy supplied from the vehicle-external charging power source 17 in the voltage boosting mode also during the subsequent second supply voltage polarity state.

[0099] Therefore, the control system 21 is configured to operate the first switch 14a of the first switch arm 14 of the second converter 9b with alternating on-off cycles, so that the charging current during the on-cycle of the first switch 10a flows from the vehicle external charging power source 17 through the second conductive line 19, the first switch 14a of the first switch arm 14 of the second converter 9b, the intrinsic reverse diode or the extrinsic reverse diode 10c associated with the first switch 10a of the first switch arm 10 of the first converter 9b, the first conductive line 19 and the associated first inductor 20, and returns to the vehicle external charging power source 17, while bypassing the electrical storage system 6, as shown in FIG. Figure 3c shown.

[0100] Similarly, during the on-period of the first switch 14a, energy begins to accumulate in the first inductor 20, and after the first switch 14a is turned off at the beginning of the subsequent off-period, the current flowing through the inductor 20 decreases and its associated magnetic field collapses to form a voltage source. The charging voltage from the vehicle external charging power source 17 combines and cooperates with the energy stored in the first inductor 20 to increase the total available charging voltage to a voltage level that exceeds the voltage level of the electrical storage system 6.

[0101] Since the first switch 14a is in an open state during the off-period, the only path provided for the combined charging current generated by the vehicle external charging power source 17 and the first inductor 20 is through the reverse diode 14d of the second switch 14b of the second converter 9b and the electrical storage system 6. This results in the energy accumulated during the on-period being transferred back into the circuit and the electrical storage system 6.

[0102] Therefore, if Figure 3d As shown, during the off period, the charging current will flow out from the negative electrode of the electrical storage system 6, flow through the intrinsic reverse diode or the non-intrinsic reverse diode 10c associated with the first switch 10a of the first switching arm 10 of the first converter 9a, the first conductive line including the first inductor 20, the vehicle external charging power source 17, the second conductive line 19, and the intrinsic reverse diode or the non-intrinsic reverse diode 14d associated with the second switch 14b of the second switching arm 14 of the second converter 9b, and flow to the positive electrode of the electrical storage system 6, thereby charging the electrical storage system 6.

[0103] Therefore, when the vehicle external charging power source 17 is a single-phase AC for charging the electrical storage system in a voltage boost mode, the control system 21 selectively controls the operation of the first switching arm 10 of the first converter 9a and the first switching arm 14 of the second converter 9b, so that the current flow alternates between the following two states: during the first supply voltage polarity state, the current flows through the first switch 10a of the first switching arm 10 of the first converter 9a for charging the electrical storage system 6, and during the second supply voltage polarity state, the current flows through the first switch 14a of the first switching arm 14 of the second converter 9b for charging the electrical storage system 6.

[0104] In certain applications or implementations of the vehicle electrical system, it may be desirable not only to increase the supply voltage level, but also to decrease the supply voltage level from the vehicle external charging power source 17, also referred to as a step-down-step-up conversion. For example, if the nominal voltage level of the electrical storage system is lower than the DC supply voltage level of the peak voltage level of the AC single phase, then the voltage level must be decreased. Similarly, depending on the operating temperature, charge level, life, charging type or maintenance operation of the electrical storage system 6, the electrical storage system 6 may sometimes require a charging voltage level lower than the DC supply voltage level of the peak voltage level of the AC single phase, and sometimes a higher charging voltage level. This will be referred to below. Figure 4 and Figure 5a-5d Another exemplary embodiment of a vehicle electrical system including such voltage step-up and voltage step-down capabilities is described below.

[0105] Specifically, Figure 4 The vehicle electrical system may have the same Figure 2The same design and function as described, but also includes: a first power switch 30, which is arranged on one of the first conductive line 18 and the second conductive line 19 and is configured to selectively open and close the conductive path associated with the first conductive line or the second conductive line 18, 19; and a step-down switch 31, which is operatively connected to the first conductive line 18 and the second conductive line 19 and is configured to selectively open and close the connection between the first conductive line or the second conductive line 18, 19, wherein the first power switch 30, the step-down switch 31 and the first inductor 20 are arranged to allow current to flow between a portion of the first conductive line 18 and a portion of the second conductive line 19 via the step-down switch 31 and the first inductor 20 when the first power switch 30 is in an open state.

[0106] In other words, the step-down switch 31 and the first inductor 20 are arranged to allow current to flow between the first switch arm 10 of the first converter 9a and the first switch arm 14 of the second converter 9b via the first conductive line 18, the first inductor 20, the step-down switch 31 and the second conductive line 19 when the first power switch 30 is in the off state.

[0107] In addition, the first power switch 30, the step-down switch 31 and the first inductor 20 are also arranged to allow current to flow between the first switch arm 10 of the first converter 9a and the first switch arm 14 of the second converter 9b via the first conductive line 18, the first inductor 20, the first power switch 30, the vehicle external charging power supply 17 and the second conductive line 19 when the step-down switch 31 is in the off state.

[0108] Thus, voltage step-down conversion is achieved by appropriately switching the first power switch 30 and the step-down switch 31 of the DC power source from the vehicle external charging power source 17 and the single-phase AC power source.

[0109] The implementation of the first power switch 30, the buck switch 31 and the first inductor 20 within the first conductive path 18 and the second conductive path 19 can be performed in various ways. For example, one terminal of the buck switch 31 is connected to the first conductive path 18 at the first connection point 32, and the other terminal of the buck switch 31 is connected to the second conductive path 19 at the second connection point 33. The first inductor 20 is arranged in the first conductive path 18 at a position between the first connection point 32 and the first switch leg 10 of the first converter 9a, or in the second conductive path 19 at a position between the second connection point 33 and the first switch leg 14 of the second converter 9b. In addition, the first power switch 30 is arranged in the first conductive path 18 at a position between the first connection point 32 and the terminal 7, or in the second conductive path 19 at a position between the second connection point 33 and the terminal 7.

[0110] The control system 21 may be operatively coupled to the first power switch 30 and the buck switch 31 and configured to control the operation of the switches 30 , 31 .

[0111] The voltage step-up and step-down devices can be implemented using conventional rack-mounted converters 9a, 9b and electric machines 5a, 5b. Therefore, it may be beneficial to arrange the first inductor 20, the first power switch 30 and the step-down switch 31 on a common relatively small circuit board 34 separate from the first converter 9a and the second converter 9b and from the first electric machine 5a and the second electric machine 5b. Therefore, the required operating functions can be easily and cost-effectively obtained in a modular approach without the need for dedicated or customized converters 9a, 9b or electric machines 5a, 5b.

[0112] The circuit board may also additionally include a grid voltage monitoring section. For safety reasons and to ensure full power factor operation, the grid voltage can be continuously monitored. It is also possible to identify whether the peak value of the grid voltage is greater or less than the desired charging voltage and control the charging process accordingly, for example by switching between voltage step-up operation and voltage step-down operation.

[0113] Furthermore, due to the bidirectional structure of the charger and the vehicle electrical system, the disclosed vehicle electrical system can actually also be used for vehicle-to-grid operation, i.e., for transferring electrical energy from the vehicle's electrical storage system 6 to the vehicle's external charging power source 17, and thus to the grid, for powering electrical loads associated with the grid. Thus, the vehicle electrical system of the present disclosure enables the use of the vehicle's electrical storage system 6 to respond to power peaks of the grid. Thus, the vehicle electrical system can also be used as an emergency power source for other stationary or non-stationary applications.

[0114] Reference Figure 4 The operation of the vehicle electrical system in the voltage boost mode described above can be as described above with reference to Figure 3a-3d The above is performed as described above, but only the first power switch 30 is always in the closed state and the step-down switch 31 is always in the open state. This corresponds to Figure 2 Therefore, we will not repeat the circuit layout here. Figure 4 Details regarding the operation of the vehicle's electrical system in boosted voltage mode.

[0115] However, the following will refer to Figure 5a-5d Detailed Description Figure 4 An exemplary embodiment of a vehicle electrical system operating in a voltage step-down mode, wherein: Figure 5a and 5b A vehicle electrical system is shown in a first supply voltage polarity state, and Figure 5c and 5dThe vehicle electrical system is shown in a second supply voltage polarity state.

[0116] Typically, when the control system 21 is configured to charge the electrical storage system 6 in the voltage step-down mode using electrical energy provided from the vehicle external charging power source 17, the control system 21 is configured to operate the first power switch 30 and the step-down switch 31 synchronously and in alternating on-off cycles.

[0117] Moreover, when the control system 21 is configured to charge the electrical storage system 6 using electric energy provided from the vehicle external charging power source 17 in the voltage step-down mode, the control system 21 is configured to set the first power switch 30 to a closed state when the step-down switch 31 is set to an open state, and vice versa (set the first power switch 30 to an open state when the step-down switch 31 is set to a closed state).

[0118] In more detail, refer to Figure 5a When the control system 21 of the vehicle electrical system is configured to charge the electrical storage system 6 using electrical energy provided from the vehicle external charging power source 17 in a voltage step-down mode during a first supply voltage polarity state, the control system 21 is configured to be able to operate the first power switch 30 and the step-down switch 31 so that the charging current during the on-period of the first power switch 30 flows from the negative electrode of the electrical storage system 6 through the intrinsic reverse diode or the non-intrinsic reverse diode 14c associated with the first switch 14a of the first switching arm 14 of the second converter 9b, the second conductive line 19, the vehicle external charging power source 17, the first conductive line 18 including the first inductor 20, and the intrinsic reverse diode or the non-intrinsic reverse diode 10d associated with the second switch 10b of the first switching arm 10 of the first converter 9a, to the positive electrode of the electrical storage system 6.

[0119] During the on-cycle of the first power switch 30, the charging current will start from zero and begin to increase. However, the first inductor will generate an opposite voltage across its (multiple) terminals in response to the increasing charging current. This voltage drop across the first inductor offsets the voltage of the vehicle external charging power source 17 and thus reduces the net voltage across the electrical storage system 6 so that the required step-down voltage is provided. Over time, the rate of change of the charging current decreases and the voltage across the first inductor also decreases, thereby causing the charging voltage on the electrical storage system 6 to increase. During this period, the first inductor stores energy in the form of a magnetic field.

[0120] After a short period of time, depending on the voltage level of the vehicle external charging power source 17 and the desired charging voltage level on the electrical storage system 6, the first power switch 30 will be opened and the buck switch will be closed, i.e. the on-cycle of the first power switch 30 ends and the on-cycle of the buck switch begins.

[0121] Therefore, if Figure 5b As illustrated, when the control system 21 is configured to charge the electrical storage system 6 using electrical energy provided from a charging power source 17 external to the vehicle in a voltage step-down mode, the control system 21 is configured to be able to operate the first power switch 30 and the step-down switch 31 so that the charging current during the on-cycle of the step-down switch 31 flows from the negative electrode of the electrical storage system 6 through an intrinsic reverse diode or a non-intrinsic reverse diode 14c associated with the first switch 14a of the first switch arm 14 of the second converter 9b, the second conductive path 19, the step-down switch 31 in an unclosed state, the first conductive path 18 including the first inductor 20, and an intrinsic reverse diode or a non-intrinsic reverse diode 10d associated with the second switch 10b of the first switch arm 10 of the first converter 9a, to the positive electrode of the electrical storage system 6.

[0122] In other words, when the first power switch 30 is turned off and the buck switch 31 is closed, the external voltage source 17 will be disconnected from the charging circuit and the charging current will begin to decrease. However, the reduced current will generate a voltage drop across the first inductor, which is caused by the weakening of the energy stored in the inductor's magnetic field, which makes the first inductor a current source that drives a continuous charging current. Over time, the voltage drop of the first inductor becomes smaller and the charging current weakens.

[0123] Therefore, the duty cycle of the first power switch 30 , for example achieved by appropriate pulse width modulation of the first power switch 30 , determines the resulting charging voltage level.

[0124] Refer to Figure 5a and 5b The two described step-down switching states are performed under the condition that the vehicle external charging power source 17 supplies electric power (e.g., DC power) with the relevant supply voltage polarity state. However, since the step-down switching operation only involves the appropriate switching of the first power switch 30 and the step-down switch 31, and all switches of the first converter 9a and the second converter 9b can be in the always-off state, Figure 5a and 5b The above switching operations shown apply to both supply voltage polarity states.

[0125] Therefore, when the control system 21 is configured to charge the electrical storage system 6 using AC power provided from the vehicle external charging power source 17 in a voltage step-down mode, the control system 21 is configured to be able to operate the first power switch 30 and the step-down switch 31 so that the charging current alternates between the following two states: flowing through the intrinsic reverse diode or the non-intrinsic reverse diode 10d associated with the second switch 10b of the first switch arm 10 of the first converter 9a and the intrinsic reverse diode or the non-intrinsic reverse diode 14c associated with the first switch 14a of the first switch arm 14 of the second converter 9b, for charging the electrical storage system during the first supply voltage polarity state; and flowing through the intrinsic reverse diode or the non-intrinsic reverse diode 14d associated with the second switch 14b of the first switch arm 14 of the second converter 9b and the intrinsic reverse diode or the non-intrinsic reverse diode 10c associated with the first switch 10a of the first switch arm 10 of the first converter 9a, for charging the electrical storage system 6 during the second supply voltage polarity state.

[0126] Obviously, when the control system 21 is configured to charge the electrical storage system 6 using electrical energy provided from the vehicle external charging power source 17 in the voltage step-down mode, the control system 21 is configured to keep all switches of the first converter 9a and the second converter 9b in the disconnected state, that is, the non-conducting state.

[0127] Many minor modifications can be made to the schematic design of the vehicle electrical system. Figure 6 , the vehicle electrical system may additionally include a second inductor 35, wherein the first inductor 20 is arranged in one of the first conductive line 18 and the second conductive line 19, and the second inductor 35 is arranged in the other of the first conductive line 18 and the second conductive line 19. Moreover, the vehicle electrical system may additionally include a second power switch 36, wherein the first power switch 30 is arranged in one of the first conductive line 18 and the second conductive line 19, and the second power switch 36 is arranged in the other of the first conductive line 18 and the second conductive line 19. Specifically, the second power switch 30 may be arranged in the first conductive line 18 at a position between the first connection point 32 and the terminal 7, or in the second conductive line 19 at a position between the second connection point 33 and the terminal 7.

[0128] Therefore, according to some exemplary embodiments, the terminal 7 is configured to receive a single-phase AC from a vehicle external charging power source 17, wherein the vehicle electrical system includes a first power switch 30 and a second power switch 36, the first power switch 30 being arranged in the first conductive line 18 and configured to selectively open and close the first conductive line 18, and the second power switch 36 being arranged in the second conductive line 19 and configured to selectively open and close the second conductive line 19. The opening and closing of the first power switch 30 and the second power switch 36 are preferably (but not strictly required to be) synchronized and identical, that is, opened and closed at the same time.

[0129] The exemplary embodiment of the vehicle electrical system described above is configured to be provided with DC or single-phase AC from the vehicle external charging power source 17 for charging the electrical storage system 6. However, in some applications, it may be desirable to charge the electrical storage system with three-phase AC from the vehicle external charging power source 17. Figure 7 Such an exemplary embodiment is schematically shown in , where the vehicle external charging power source 17 is a three-phase power source connected to the external charging connector 23 .

[0130] Figure 7 The vehicle electrical system and reference Figure 2 The vehicle electrical system described is essentially the same, but an additional third converter 9c is added, which is connected in parallel with the first converter 9a and the second converter 9b, and a third multi-phase electric machine 5c having a plurality of stator windings is connected to the third converter 9c.

[0131] therefore, Figure 7 The vehicle electrical system is in addition to the reference Figure 2 In addition to the characteristics described, there is also a third multi-phase electric machine 5c having a plurality of stator windings 37, a third converter 9c connected to the electrical storage system 6 and connected to the third multi-phase electric machine 5c, wherein the third converter 9c has a plurality of switch arms with switches, a third conductive line 38 connecting the third pole of the terminal 7 with the first switch arm 39 of the third converter 9c, a second inductor 35 arranged in the second conductive line 19, and a third inductor 40 arranged in the third conductive line 38, wherein the first inductor 20 is arranged in In the first conductive circuit 18, and wherein the control system 21 is operatively connected to each of the first converter 9a, the second converter 9b and the third converter 9c, and is configured to control the operation of switches of the first converter 9a, the second converter 9b and the third converter 9c to prevent the charging current from passing through any of the stator windings 8, 13, 37 of the first multi-phase electric machine 5a, the second multi-phase electric machine 5b and the third multi-phase electric machine 5c during three-phase charging of the electrical storage system from a charging power source external to the vehicle.

[0132] Figure 7 The vehicle electrical system may be controlled by the control system 21 to operate in a voltage boost mode, similar to reference Figure 3a-3d Specifically, when the control system 21 is configured to use the electric energy supplied from the three-phase vehicle external charging power source 17 in the voltage boost mode, Figure 7 When charging the electrical storage system 6 of the present invention, the control system 21 is configured to continuously and in an alternating on-off cycle operate each of the first switch 10a of the first switch arm 10 of the first converter 9a, the first switch 14a of the first switch arm 14 of the second converter 9b, and the first switch 39a of the first switch arm 39 of the third converter 9c. Specifically, each of the first switches 10a, 14a, 39a is controlled to operate in an alternating on-off cycle as long as it is operated under a positive supply voltage polarity state of the AC power source. During a subsequent negative supply voltage polarity state of the AC power source to the first switches 10a, 14a, 39a, the first switches 10a, 14a, 39a may be in an off state, and the charging current flows in the opposite direction through the intrinsic reverse diode or the extrinsic reverse diode 10c, 14c, 39c associated with each of the first switches 10a, 14a, 39a, as similarly described with reference to FIG. Figure 3a-3d described.

[0133] If the charging of the electric storage system requires voltage reduction when powered by three-phase AC, an isolated or non-isolated DC / DC converter 41 can be arranged between the positive channel (positive rail) and the negative channel (negative rail) of the DC bus of the vehicle electrical system and the electric storage system 6, as shown in FIG. Figure 8 Schematically shown in FIG.

[0134] In addition, Figure 8 As shown, the vehicle electrical system may also include first, second and third power switches in the first conductive path 18, the second conductive path 19 and the third conductive path 44, respectively.

[0135] The present disclosure also relates to a method for charging an electrical storage system of a vehicle electrical system, as described with reference to Figure 2 , Figure 3a-3d or Figure 7 Described. Reference Fig. 9 , Fig. 9The basic steps are shown, the method comprises a first step S1, wherein a first converter 9a is connected to a first multiphase electric machine 5a having a plurality of stator windings 8 and to the electric storage system 6, wherein the first converter 9a has a plurality of switch arms 10, 11, 12 with switches. The method also comprises a second step S2, wherein a second converter 9b is connected to a second multiphase electric machine 5b having a plurality of stator windings 13 and to the electric storage system 6, wherein the second converter 9b has a plurality of switch arms 14, 15, 16 with switches. The method also comprises: a third step S3: connecting the first pole of the terminal 7 to the first switch arm 10 of the first converter 9a via a first conductive line 18; and a fourth step S4: connecting the second pole of the terminal 7 to the first switch arm 14 of the second converter 9b via a second conductive line 19. The method then also includes: a fifth step S5: providing a first inductor 20 on one of the first conductive line 18 and the second conductive line 19; and a sixth step S6: connecting a terminal 7 having multiple poles to a vehicle external charging power source 17 configured to supply single-phase AC or multi-phase AC or DC; and a final seventh step S7: controlling the operation of the switches 10a, 14a of the first converter 9a and the second converter 9b to prevent the charging current from passing through any of the stator windings 8, 13 of the first multi-phase electric machine 5a and the second multi-phase electric machine 5b during the transfer of charge from the vehicle external charging power source 17 to the electrical storage system 6.

[0136] It is to be understood that the above description is merely exemplary in nature and is not intended to limit the present disclosure, its application, or uses. Although specific examples have been described in the specification and illustrated in the drawings, those skilled in the art will appreciate that various changes may be made and equivalents may be substituted for their elements without departing from the scope of the present disclosure as defined in the claims. In addition, modifications may be made to adapt specific circumstances or materials to the teachings of the present disclosure without departing from the basic scope thereof. For example, the above reference to Fig. 9 The method described herein, some of the method steps may be performed in another order than the order described. For example, each of steps S1-S6 may be performed in substantially any internal order. Therefore, the method discussed is only one embodiment of the present disclosure contemplated, and a person skilled in the art understands that the order in which the components are connected is not necessarily required for the functioning of the method for charging an electrical storage system.

[0137] Therefore, it is not intended that the present disclosure be limited to the specific examples illustrated by the drawings and described in the specification as the best mode currently conceived for carrying out the teachings of the present disclosure, but rather the scope of the present disclosure will include any embodiment falling within the scope of the foregoing description and the appended claims. The reference signs mentioned in the claims shall not be construed as limiting the scope of the subject matter protected by the claims, and their only function is to make the claims easier to understand.

Claims

1. A vehicle electrical system, comprising: Electrical storage systems (6); A first multi-phase electric machine (5a) having a plurality of stator windings (8); a first converter (9a), the first converter (9a) being connected to the electrical storage system (6) and to the first multi-phase electric machine (5a), wherein the first converter (9a) has a plurality of switch arms (10, 11, 12) with switches (10a, 10b, 11a, 11b, 12a, 12b); a second multi-phase electric machine (5b) having a plurality of stator windings (13); a second converter (9b), the second converter (9b) being connected to the electrical storage system (6) and to a second multiphase electric machine (5b), wherein the second converter (9b) has a plurality of switch arms (14, 15, 16) with switches (14a, 14b); A terminal (7) having a plurality of poles and configured to receive single-phase AC or multi-phase AC or DC from a vehicle external charging power source (17); A first conductive line (18), the first conductive line (18) connecting a first pole of the terminal (7) to a first switch arm (10) of a first converter (9a); A second conductive line (19), the second conductive line (19) connecting the second pole of the terminal (7) to the first switch arm (14) of the second converter (9b); a first inductor (20), the first inductor (20) being arranged on one of the first conductive path (18) and the second conductive path (19); and A control system (21) operatively coupled to the first converter (9a) and the second converter (9b) and configured to control the operation of switches of the first converter (9a) and the second converter (9b) to prevent charging current from passing through either of the stator windings (8, 13) of the first multi-phase electric machine (5a) and the second multi-phase electric machine (5b) during transfer of charge from the vehicle external charging power source (17) to the electrical storage system (6).

2. The vehicle electrical system according to claim 1, wherein: When the control system (21) is configured to charge the electrical storage system (6) in a voltage boost mode using electrical energy provided from the vehicle external charging power source (17), the control system (21) is configured to operate the first switch (10a) of the first switch arm (10) of the first converter (9a) in an alternating on-off cycle, so that the charging current during the on-cycle flows from the vehicle external charging power source (17) through the first conductive line (18), the first switch (10a) of the first switch arm (10) of the first converter (9a), an intrinsic reverse diode or an extrinsic reverse diode (14c) associated with the first switch (14a) of the first switch arm (14) of the second converter (9b), and the second conductive line (18). 9), the first inductor (20), and returns to the vehicle external charging power source (17), while bypassing the electrical storage system (6), and allowing the charging current during the off period to flow from the negative electrode of the electrical storage system (6), through the intrinsic reverse diode or the non-intrinsic reverse diode (14c) associated with the first switch (14a) of the first switch arm (14) of the second converter (9b), the second conductive line (19), the first inductor (20), the vehicle external charging power source (17), the first conductive line (18), the intrinsic reverse diode or the non-intrinsic reverse diode (10d) associated with the second switch (10b) of the first switch arm (10) of the first converter (9a), to the positive electrode of the electrical storage system (6).

3. The vehicle electrical system according to claim 2, wherein: When the vehicle external charging power source (17) is AC for charging the electrical storage system (6) in a voltage boost mode, the control system (21) selectively controls the operation of the first switch arm (10) of the first converter (9a) and the first switch arm (14) of the second converter (9b) so that the current flow alternates between the following two states: During a first supply voltage polarity state, current flows through a first switch (10a) of a first switching arm (10) of a first converter (9a) for charging the electrical storage system (6); as well as During the second supply voltage polarity state, current flows through the first switch (14a) of the first switching arm (14) of the second converter (9b) for charging the electrical storage system (6).

4. The vehicle electrical system according to claim 1, wherein: The vehicle electrical system further comprises: A first power switch (30), which is arranged on one of the first conductive line (18) and the second conductive line (19) and is configured to selectively open and close the first conductive line (18) or the second conductive line (19); and a step-down switch (31), the step-down switch (31) being operatively connected to the first conductive line (18) and the second conductive line (19), and being configured to selectively open and close the connection between the first conductive line (18) and the second conductive line (19); The first power switch (30), the step-down switch (31) and the first inductor (20) are arranged to allow current to flow between a portion of the first conductive line (18) and a portion of the second conductive line (19) via the step-down switch (31) and the first inductor (20) when the first power switch (30) is in an off state.

5. The vehicle electrical system according to claim 4, wherein: When the control system (21) is configured to charge the electrical storage system (6) in a voltage step-down mode using electrical energy provided from the vehicle external charging power source (17), the control system (21) is configured to synchronously operate the first power switch (30) and the step-down switch (31) in alternating on-off cycles.

6. The vehicle electrical system according to claim 4, wherein: When the control system (21) is configured to charge the electrical storage system (6) in a voltage step-down mode using electric energy provided from a charging power source (17) external to the vehicle, the control system (21) is configured to set the first power switch (30) to a closed state when the step-down switch (31) is set to an open state, and to set the first power switch (30) to an open state when the step-down switch (31) is set to a closed state.

7. The vehicle electrical system according to claim 4, wherein: When the control system (21) is configured to charge the electrical storage system (6) in a voltage step-down mode using electrical energy provided from a charging power source (17) external to the vehicle, the control system (21) is configured to keep all switches of the first converter (9a) and the second converter (9b) in an open state.

8. The vehicle electrical system according to claim 4, wherein: When the control system (21) is configured to charge the electrical storage system (6) in a voltage step-down mode using electrical energy provided from the vehicle external charging power source (17), the control system (21) is configured to operate the first power switch (30) and the step-down switch (31) so that the charging current during the on-period of the first power switch (30) flows from the negative electrode of the electrical storage system (6), through an intrinsic reverse diode or an extrinsic reverse diode (14c) associated with the first switch (14a) of the first switch arm (14) of the second converter (9b), the second conductive line (19), the first inductor (20), the vehicle external charging power source (17), the first conductive line (18), an intrinsic reverse diode or an extrinsic reverse diode (10d) associated with the second switch (10b) of the first switch arm (10) of the first converter (9a), and flows to the positive electrode of the electrical storage system (6).

9. The vehicle electrical system according to claim 4, wherein: When the control system (21) is configured to charge the electrical storage system (6) in a voltage step-down mode using electrical energy provided from a charging power source (17) external to the vehicle, the control system (21) is configured to operate the first power switch (30) and the step-down switch (31) so that the charging current during the on-period of the step-down switch (31) flows from the negative electrode of the electrical storage system (6) through an intrinsic reverse diode or an extrinsic reverse diode (14c) associated with the first switch (14a) of the first switch arm (14) of the second converter (9b), the second conductive line (19), the first inductor (20), the step-down switch (31), the first conductive line (18), an intrinsic reverse diode or an extrinsic reverse diode (10d) associated with the second switch (10b) of the first switch arm (10) of the first converter (9a), and flows to the positive electrode of the electrical storage system (6).

10. The vehicle electrical system according to claim 4, wherein: When the control system (21) is configured to charge the electrical storage system (6) in the voltage step-down mode using the electric energy provided from the vehicle external charging power source (17), the control system (21) is configured to be able to operate the first power switch (30) and the step-down switch (31) so that the charging current alternates between the following two states: flowing through an intrinsic or extrinsic reverse diode (10d) associated with a second switch 10b of a first switching leg (10) of a first converter (9a) and an intrinsic or extrinsic reverse diode (14c) associated with a first switch (14a) of a first switching leg (14) of a second converter (9b) for charging the electrical storage system (6) during a first supply voltage polarity state; and Flows through an intrinsic reverse diode or an extrinsic reverse diode (14d) associated with the second switch 14(b) of the first switch arm (14) of the second converter (9b) and an intrinsic reverse diode or an extrinsic reverse diode (10c) associated with the first switch (10a) of the first switch arm (10) of the first converter (9a) for charging the electrical storage system (6) during the second supply voltage polarity state.

11. A vehicle electrical system according to any one of the preceding claims, in, When the control system (21) is configured to charge the electrical storage system (6) in a voltage boost mode using electrical energy provided from a charging power source (17) external to the vehicle, the control system (21) is configured to control the operation of the switches of the first converter (9a) and the second converter (9b) by operating the first switch (10a) of the first switch arm (10) of the first converter (9a) in alternating on-off cycles, while controlling the other switches of the first converter (9a) and the second converter (9b) to remain in an off state, so as to prevent charging current from passing through any of the stator windings (8, 13) of the first multi-phase electric machine (5a) and the second multi-phase electric machine (5b); and / or Wherein, when the control system (21) is configured to charge the electrical storage system (6) in a voltage step-down mode using electric energy provided from a charging power source (17) external to the vehicle, the control system (21) is configured to control the operation of the switches of the first converter (9a) and the second converter (9b) by keeping all switches of the first converter (9a) and the second converter (9b) in an off state, so as to prevent the charging current from passing through any of the stator windings (8, 13) of the first multi-phase electric machine (5a) and the second multi-phase electric machine (5b).

12. The vehicle electrical system according to any one of claims 1 to 10, wherein: The vehicle electrical system further comprises: a third multi-phase electric machine (5c) having a plurality of stator windings (37); a third converter (9c), the third converter (9c) being connected to the electrical storage system (6) and to a third multi-phase electric machine (5c), wherein the third converter (9c) has a plurality of switch arms (39) with switches (39a); A third conductive line (38), the third conductive line (38) connecting the third pole of the terminal (7) to the first switch arm (39) of the third converter (9c); a second inductor (35) disposed in the second conductive path (19); a third inductor (40) disposed in the third conductive path (38); wherein the first inductor (20) is arranged in the first conductive line (18); and Wherein, the control system (21) is operatively connected to each of the first converter (9a), the second converter (9b) and the third converter (9c), and is configured to control the operation of switches of the first converter (9a), the second converter (9b) and the third converter (9c) so as to prevent the charging current from passing through any of the stator windings (8, 13, 17) of the first multi-phase electric machine (5a), the second multi-phase electric machine (5b) and the third multi-phase electric machine (5c) during three-phase charging of the electrical storage system (6) from the external charging power source (17) of the vehicle.

13. A method for charging an electrical storage system (6) of an electrical system of a vehicle, the method comprising: Connecting a first converter (9a) to a first multiphase electric machine (5a) having a plurality of stator windings (8) and to the electric storage system (6), wherein the first converter (9a) has a plurality of switch arms (10, 11, 12) with switches (10a, 10b, 11a, 11b, 12a, 12b); Connecting a second converter (9b) to a second multiphase electric machine (5b) having a plurality of stator windings (13) and to the electric storage system (6), wherein the second converter (9b) has a plurality of switch arms (14, 15, 16) with switches (14a, 14b); Connecting a first pole of the terminal (7) to a first switching arm (10) of a first converter (9a) via a first conductive line (18); Connecting the second pole of the terminal (7) to the first switch arm (14) of the second converter (9b) via a second conductive line (19); Providing a first inductor (20) on one of the first conductive path (18) and the second conductive path (19); connecting the terminal (7) having multiple poles to a vehicle external charging power source (17) configured to supply single-phase AC or multi-phase AC or DC; and Controlling the operation of switches of the first converter (9a) and the second converter (9b) to prevent charging current from passing through either of the stator windings (8, 13) of the first multi-phase electric machine (5a) and the second multi-phase electric machine (5b) during the transfer of charge from the vehicle external charging power source (17) to the electrical storage system (6).

14. The method according to claim 13, wherein: When the electrical storage system (6) is charged in the voltage boost mode using electrical energy provided from the vehicle external charging power source (17), the first switch (10a) of the first switch arm (10) of the first converter (9a) is operated in an alternating on-off cycle, so that the charging current during the on-cycle flows from the vehicle external charging power source (17), through the first conductive line (18), the first switch (10a) of the first switch arm (10) of the first converter (9a), an intrinsic reverse diode or an extrinsic reverse diode (14c) associated with the first switch of the first switch arm of the second converter (9b), the second conductive line (19), the first inductor (20), and returns to the first switch of the vehicle external charging power source (17). The vehicle external charging power source (17) is passed through while bypassing the electrical storage system (6), and the charging current during the off period flows from the negative electrode of the electrical storage system (6) through an intrinsic reverse diode or an extrinsic reverse diode (14c) associated with the first switch (14a) of the first switch arm (14) of the second converter (9b), a second conductive line (19), a first inductor (20), the vehicle external charging power source (17), a first conductive line (18), an intrinsic reverse diode or an extrinsic reverse diode (10d) associated with the second switch (10b) of the first switch arm (10) of the first converter (9a), and flows to the positive electrode of the electrical storage system (6).

15. The method according to claim 13, further comprising: Providing a first power switch (30) on one of the first conductive line (18) and the second conductive line (19), the first power switch (30) being configured to selectively open and close the first conductive line (18) or the second conductive line (19); as well as Providing a step-down switch (31), which is operatively connected to the first conductive line (18) and the second conductive line (19), and is configured to selectively open and close the connection between the first conductive line (18) and the second conductive line (19); The first power switch (30), the step-down switch (31) and the first inductor (20) are arranged to allow current to flow between a portion of the first conductive line (18) and a portion of the second conductive line (19) via the step-down switch (31) and the first inductor (20) when the first power switch (30) is in an off state.

16. The method according to claim 15, further comprising: By operating the first power switch (30) and the step-down switch (31), the electrical storage system (6) is charged in a voltage step-down mode using electric energy provided from the vehicle external charging power source (17), so that: The charging current during the on-cycle of the first power switch (30) flows from the negative electrode of the electrical storage system (6), through an intrinsic reverse diode or an extrinsic reverse diode (14c) associated with the first switch (14a) of the first switch arm (14) of the second converter (9b), a second conductive line (19), a first inductor (20), the vehicle external charging power source (17), a first conductive line (18), an intrinsic reverse diode or an extrinsic reverse diode (10d) associated with the second switch (10ba) of the first switch arm (10) of the first converter (9a), and flows to the positive electrode of the electrical storage system (6), and The charging current during the on-period of the buck switch (31) flows from the negative electrode of the electrical storage system (6), through an intrinsic reverse diode or an extrinsic reverse diode (14c) associated with the first switch (14) of the first switch arm (14) of the second converter (9b), a second conductive line (19), a first inductor (20), the buck switch (31), a first conductive line (18), an intrinsic reverse diode or an extrinsic reverse diode (10d) associated with the second switch (10b) of the first switch arm (10) of the first converter (9a), and flows to the positive electrode of the electrical storage system (6).

17. The method according to any one of the preceding claims 13 to 16, in, When the electrical storage system (6) is charged in a voltage boost mode using electrical energy provided from a charging power source (17) external to the vehicle, the operation of the switches of the first converter (9a) and the second converter (9b) is controlled by operating the first switch (10a) of the first switch arm (10) of the first converter (9a) in alternating on-off cycles, while the other switches of the first converter (9a) and the second converter (9b) are controlled to remain in an off state, thereby preventing charging current from passing through any of the stator windings (8, 13) of the first multi-phase electric machine (5a) and the second multi-phase electric machine (5b); and / or When the electrical storage system (6) is charged in a voltage step-down mode using electric energy provided from a charging power source (17) external to the vehicle, the operation of the switches of the first converter (9a) and the second converter (9b) is controlled by keeping all switches of the first converter (9a) and the second converter (9b) in an off state, thereby preventing the charging current from passing through any of the stator windings (8, 13) of the first multi-phase electric machine (5a) and the second multi-phase electric machine (5b).

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