Method for operating an inverter and vehicle propulsion system

Abstract

Methods and systems for operating an inverter coupled to an electric motor are provided. The inverter has a plurality of high-speed switching devices and a plurality of low-speed switching devices coupled to the electric motor. A condition indicating a deceleration of the electric motor is detected. The inverter switches between a first operating mode and a second operating mode during the deceleration of the electric motor. In the first operating mode, each switching device of the plurality of high-speed switching devices is activated, and each switching device of the plurality of low-speed switching devices is deactivated. In the second operating mode, each switching device of the plurality of low-speed switching devices is activated, and each switching device of the plurality of high-speed switching devices is deactivated.

Description

Technical field

[0001] The present invention relates generally to vehicle electrical systems. In particular, the present invention relates to vehicle electrical systems and methods for controlling an inverter during the deceleration of a motor connected to the inverter. Background of the invention

[0002] In recent years, technological advances and evolving tastes have led to significant changes in automotive design. One such change involves the increasing complexity of electrical systems in automobiles, particularly those with alternative powertrains (or drive systems) that utilize electrical power supplies, such as hybrid and battery-electric vehicles. These alternative-powertrain vehicles typically employ one or more electric motors, often powered by batteries, possibly in combination with another drive system, to power the wheels.

[0003] During motor deceleration, such as after a collision or an electrical fault, it is desirable to slow the motor down as quickly as possible (for example, by applying motor braking torque). The amount of motor braking torque that can be applied to the motor is partially determined by the voltage across the electrodes of the power supply (i.e., the DC connection voltage). Generally, this voltage tends to increase during motor deceleration, especially when motor braking torque is applied.

[0004] Accordingly, it is desirable to provide an electrical vehicle system or vehicle electrical system and method that allows for improved handling of the DC connection voltage during motor deceleration. Furthermore, other desirable features and characteristics of the present invention will become apparent from the following detailed description and the appended claims in conjunction with the accompanying drawings and the preceding technical field and background. Background of the invention

[0005] In one embodiment, a method for operating an inverter coupled to an electric motor is provided. The inverter has a plurality of high-speed switching devices and a plurality of low-speed switching devices coupled to the electric motor. A state indicating deceleration of the electric motor is detected. The inverter switches between a first operating mode and a second operating mode during the deceleration of the electric motor. In the first operating mode, each switching device of the plurality of high-speed switching devices is activated, and each switching device of the plurality of low-speed switching devices is deactivated. In the second operating mode, each switching device of the plurality of low-speed switching devices is activated, and each switching device of the plurality of high-speed switching devices is deactivated.

[0006] In a further embodiment, a method for operating an inverter coupled to a vehicle drive motor is provided. The inverter has a plurality of switching devices pairs. Each pair of switching devices comprises a high-switching device and a low-switching device. A condition indicating a deceleration of the vehicle drive motor is detected. The inverter switches between a first operating mode and a second operating mode during the deceleration of the electric motor for approximately the same duration in each mode. In the first operating mode, each high-switching device of the plurality of switching device pairs is activated, and each low-switching device of the plurality of switching device pairs is deactivated.In the second operating mode, each switching device is activated by the low switching devices of the majority of pairs of switching devices, and each switching device is deactivated by the high switching devices of the majority of pairs of switching devices.

[0007] In a further embodiment, a vehicle drive system is provided. The vehicle drive system comprises an electric motor with a plurality of windings, a direct current-to-alternating current (DC / AC) energy inverter with a plurality of pairs of power switching devices coupled to the plurality of windings, each pair of power switching devices comprising a high-power switching device and a low-power switching device, and a processor system operationally connected to the electric motor and the DC / AC energy inverter. The processor is configured to detect a condition indicating deceleration of the electric motor and to switch the operation of the DC / AC energy inverter between a first operating mode and a second operating mode during deceleration of the electric motor.In the first operating mode, the high-power switching devices of the majority of switching device pairs are activated, and the low-power switching devices of the majority of switching device pairs are deactivated. In the second operating mode, the low-power switching devices of the majority of switching device pairs are activated, and the high-power switching devices of the majority of switching device pairs are deactivated. Description of the drawings

[0008] The present invention is described below in conjunction with the following drawing figures, where the same reference numerals denote the same elements, and

[0009] Fig. 1 a schematic view of an exemplary automobile according to one embodiment of an embodiment;

[0010] Fig. 2 a block diagram of an inverter control system in the automobile Fig. 1 is, namely according to one embodiment; and

[0011] Fig. 3 A diagram of an energy inverter, a power supply and an electric motor in the automobile made of Fig. 1 is, namely according to one embodiment. Description of an exemplary embodiment

[0012] The following detailed description is merely exemplary and is not intended to limit the invention or its applications and uses. Furthermore, it is not intended to be limited by any theory expressly or implicitly presented in the preceding technical field, background, summary, or the following detailed description. Additionally, although the schematic diagrams shown herein represent exemplary arrangements of elements, additional interacting elements, devices, features, or components may be present in an actual embodiment. It is also preferred that Fig. 1 to Fig. 3 are merely illustrative and not to scale.

[0013] The following description refers to elements or features that are "connected" or "coupled" together. As used herein, "connected" may refer to an element / feature that is mechanically connected to (or in direct communication with) another element / feature, not necessarily directly. Likewise, "coupled" may refer to an element / feature that is directly or indirectly connected to (or in direct or indirect communication with) another element / feature, not necessarily mechanically. However, it is preferred that, although two elements below may be described as "connected" in one embodiment, in alternative embodiments similar elements may be "coupled" and vice versa.Thus, although the schematic diagrams shown herein depict exemplary arrangements of elements, additional interacting elements, devices, features or components may be present in an actual embodiment.

[0014] Fig. 1 to Fig. Figure 3 shows systems for operating an inverter coupled to an electric motor. The inverter has multiple high-speed switching devices and multiple low-speed switching devices, which are coupled to the electric motor. A condition indicating a deceleration of the electric motor is detected. The inverter switches between a first operating mode and a second operating mode during the deceleration of the electric motor. In the first operating mode, each switching device of the multiple high-speed switching devices is activated, and each switching device of the multiple low-speed switching devices is deactivated. In the second operating mode, each switching device of the multiple low-speed switching devices is activated, and each switching device of the multiple high-speed switching devices is deactivated.

[0015] Fig. Figure 1 is a schematic view of a vehicle (or “automobile” or “vehicle propulsion system”) 10 , specifically according to one embodiment. The automobile 10 includes a powertrain 12 , a car body 14 four wheels 16 as well as an electronic control system 18 The bodywork 14 is on the drivetrain 12 arranged and essentially comprises the other components of the automobile 10 The bodywork 14 and the powertrain 12 can together form a frame. The wheels 16 are each rotatable with the drive train 12 near a corresponding corner of the bodywork 14 coupled.

[0016] The automobile 10It can be one of a number of different types of automobiles, such as a sedan, a station wagon, a truck, or a sports utility vehicle (SUV), and can be two-wheel drive (2WD) (that is, rear-wheel drive or front-wheel drive), four-wheel drive (4WD), or all-wheel drive (AWD). The automobile 10 It may also have one or a combination of a number of different types of propulsion, such as a gasoline or diesel fuel-powered internal combustion engine, a 'flex fuel vehicle' (FFV) internal combustion engine (i.e. using a mixture of gasoline and alcohol), a fuel cell vehicle internal combustion engine, an internal combustion engine powered by a gas mixture (for example, hydrogen and natural gas), an internal combustion / electric motor hybrid engine (i.e., as in a hybrid electric vehicle (HEV)), and an electric motor.

[0017] The automobile 10 in Fig. 1 is a HEV, and also includes a drive unit 20 , a battery (for example, a high-voltage battery) 22 , as well as a power electronics arrangement (for example, an inverter or an inverter assembly) 24 The drive arrangement 20 is mechanically connected to at least some of the wheels 16 through drive shafts 26 coupled and includes an internal combustion engine 28 and an electric motor / generator (or drive motor) 30 The internal combustion engine 28 and / or the electric motor 30 are integrated in such a way that one or both elements are mechanically connected to the drive shafts via a gearbox (not shown). 26 are coupled. The battery 22 It could, for example, be a lithium-ion battery and could include an integrated voltmeter.

[0018] In one embodiment, the automobile 10 a “serial HEV”, in which the internal combustion engine 28 is not directly coupled to the gearbox, but is coupled to a generator (not shown) which is used to power the electric motor 30 to propel. In another embodiment, the automobile 10 a “parallel HEV”, in which the internal combustion engine 28 is directly coupled to the gearbox, for example by the rotor of the electric motor 30 rotatably connected to the drive shaft of the internal combustion engine 28 is coupled.

[0019] The electronic control system 18 is operationally connected to the drive arrangement 20 , the battery 22 and the inverter 24 Although not shown in detail, the electronic control system includes 18various sensors and vehicle control modules or electronic control units (ECUs), such as an inverter control module, a motor control unit and a vehicle control unit, as well as at least one processor (or processor or processing system) and / or a memory containing instructions stored therein (or on another computer-readable medium) for carrying out the process steps and procedures as described below.

[0020] With reference to Fig. 2 is an inverter control system 34 shown according to an exemplary embodiment of the present invention. The inverter control system 34 includes a controller (or processor) 36 in operational connection with a pulse width modulation (PWM) modulator 38 (or a pulse width modulator) and the inverter 24 (at one of its outputs). The PWM modulator 38 is equipped with a gate driver39 coupled, which in turn connects to an input of the inverter 24 The inverter has a coupled output. 24 has a second one with the engine 30 coupled output. The control 36 and the PWM modulator 38 can be like in Fig. 1 shown integrally with the electronic control system 18 be trained.

[0021] Fig. Figure 3 shows the battery (and / or DC voltage source) in a schematic way. 22 , the inverter 24 , as well as the engine 30 out of Fig. 1 and Fig. 2 in a more detailed view. In the illustrated embodiment, the inverter comprises 24 one with the engine 30 coupled three-phase circuit. In particular, the inverter includes 24 a switching device network with a first input, which is connected to the battery 22(that is, a voltage source or supply (VDC)) is coupled, and one connected to the motor 30 coupled output. Although a single voltage source is shown, a distributor DC connection or link can be used with two or more sources arranged in series.

[0022] The expert will prefer that the electric motor 30 in one embodiment it is a permanent magnet electric motor and a stator arrangement 40 and a rotor arrangement 42 includes the stator arrangement. 40 comprises a plurality (for example, three) of conductive coils or windings 44 , 46 as well as 48 , each of which is one of the three phases of the electric motor 30 is assigned, as is generally known. The rotor arrangement 42 includes a plurality of magnets 50 and is rotatably connected to the stator arrangement 40coupled, as is generally known. The magnets 50 They can comprise multiple (for example, sixteen) electromagnetic poles, as is generally known. The description above is assumed to serve merely as an example of a type of electric motor to be used.

[0023] The switching device network comprises three pairs of series power switching devices (or switching devices or components) with antiparallel diodes (that is, antiparallel to each switching device) corresponding to each of the phases of the motor. 30 . Each of the pairs of series switching devices includes a first switching device, or transistor (that is, a "high" switching device). 52 , 54 as well as 56 with a first connection, which is connected to a positive electrode 63 the voltage source 22coupled, and a second switching device (that is, a "low" switching device) 58 , 60 as well as 62 with a second connection, which is connected to a negative electrode 65 the voltage source 22 is coupled, and with a first connection, which is connected to a second connection of the respective first switching device 52 , 54 and 56 is coupled. Thus, the first connection of the up-switching devices is 52 , 54 and 56 and the second terminals of the low-voltage switching devices 58 , 60 and 62 at the DC connection of the voltage source 22 connected (that is, to the positive and negative electrodes) 63 and 65 the voltage source 22 ).

[0024] As is generally known, each of the switching devices can 52 – 62They can be in the form of individual semiconductor devices, such as insulated center-electrode bipolar transistors (IGBTs) within integrated circuits, which are formed on semiconductor (e.g., silicon) substrates (e.g., a chip). As shown, a diode is 64 in an antiparallel arrangement (that is, a “flyback” or “freewheeling” diode) with each of the switching devices 52 – 62 connected. Thus, each of the switching devices can be 52 – 62 and the corresponding diode 64 a switching device-diode pair or group, of which six are included in the illustrated embodiment. The inverter 24 It also includes current sensors (for example, Hall effect sensors) 66 , to control the flow of current through the switching devices 52 – 62 and / or the windings 44 , 46 and 48to detect.

[0025] Furthermore with reference to Fig. The inverter comprises 3 24 also a voltage disconnect switch (or battery connector) 68 and a DC link capacitor 70 The battery connector 68 can be similar to switching devices 52 – 62 be and connected to the positive terminal of the voltage source (that is, the battery) 22 be connected. In other embodiments, the voltage-disconnecting switching device can be a mechanically constructed connector, such as a relay. The DC connection capacitor 70 is connected to the DC connection of the system (that is, to the positive and negative terminals of the voltage source) 22 ).

[0026] With reference to Fig. 1. The automobile 10 during normal operation (i.e., driving) by providing energy or torque to the wheels16 through the internal combustion engine 28 and the electric motor 30 in an alternating manner and / or by the internal combustion engine 28 and the electric motor 30 operated simultaneously. To power the electric motor 30 To power it, DC energy is drawn from the battery. 22 (and, in the case of a fuel cell car, a fuel cell) the inverter 24 provided, which converts the DC energy into AC energy before the energy is sent to the electric motor 30 is transferred. The person skilled in the art will prefer that the conversion of DC energy into AC energy is carried out essentially by operating (i.e., repeatedly switching) the switching devices. 52 – 62 in the inverter 24 is performed at an operating (or switching) frequency, such as 12 kilohertz (kHz).

[0027] With reference to Fig. 2 generates the control36 Generally, a pulse width modulation (PWM) signal is used to control the switching action of the inverter. 24 The inverter 24 It then converts the PWM signal into a modulated voltage waveform to operate the motor. 30 um. The inverter control system 34 out of Fig. 2 consists of several operating steps during normal operation, including, but not limited to, receiving a torque command, converting the torque command into current commands based on the current speed and available voltage, and performing control on these current commands. The output of the current controller (not shown) is the output voltage required to generate the necessary currents. The PWM modulator 38 and the gate driver 39 generate the necessary gate pulses (or operating cycles) which are sent to the inverter 24be transmitted to power the electric motor 30 to control the desired speed and / or torque.

[0028] It is known to the person skilled in the art that the operation of the switching devices 52 – 62 ( Fig. 3) a current flow through the windings 44 , 46 and 48 in the engine 30 caused by the interaction of this current with the magnets. 50 The generated magnetic fields cause a Lorentz force to be generated, so that the rotor 42 is caused to move relative to the stator 40 to rotate.

[0029] According to one aspect of the invention, upon detecting an “unexpected” condition (for example, abnormal braking), which indicates a deceleration of the motor, the system switches on. 30 (and / or the automobile) 10 (overall) indicates that the inverter 24between a "high-short" operating mode and a "low-short" operating mode. In the high-short operating mode, every high-current switching device is 52 , 54 and 56 activated while the low-level switching devices 58 , 60 and 62 are deactivated. In low-short operating mode, each of the low-current switching devices is deactivated. 58 , 60 and 62 activated while the up-switching devices 52 , 54 and 56 are deactivated. This switching operation causes the voltage at the DC connection to drop relatively quickly while the motor is running. 30 continues to run freely (that is, the rotor) 42 continues to rotate relative to the stator 40 ).

[0030] In one embodiment, a method for controlling the inverter can be used. 24 to begin with the inverter control module (in the electronic control system)18 ) detects a condition that indicates a delay in the motor 30 indicates. Examples include the fact that the automobile 10 is involved in a collision (for example, detected by the vehicle control system) or an electrical fault condition exists (for example, a winding short circuit or an overvoltage situation related to the motor). 30 , which is detected by the inverter control module). The battery 22 can from the engine 30 be separated so that the engine 30 (that is, the rotor) 42 ) “runs freely” (and slowly decelerates or brakes) and / or a braking torque or motor braking torque is applied by the inverter 24 is exercised to drive the rotor 42 to delay or slow down.

[0031] The voltage source (for example, the battery) 22 will then be by the inverter 24 and therefore from the engine 30disconnected. The disconnection is achieved by disabling (or opening or switching off) the battery connector. 68 executed.

[0032] Next, the inverter control module repeatedly switches the inverter on and off. 24 between first and second operating modes. Switching between operating modes can, for example, involve applying approximately a 50% operating cycle to each of the switching devices. 52 – 62 in a synchronized manner, so that the inverter 24 between applying a "high short" and a "low short" to the engine 30 switches. In particular, in the first operating mode all high-voltage switching devices are disabled. 52 – 56 activated (or closed or switched on), and all low-power switching devices 58 – 62 are deactivated (or opened or switched off). In the second operating mode, all low-level switching devices are disabled.58 – 62 activated and all up-switching devices 52 – 56 are deactivated.

[0033] In one embodiment, this switching is performed at the switching frequency (for example, 12 kHz), so that the time during which the inverter 24 The time spent in the first operating mode is approximately the same as in the second operating mode (i.e., a 50% operating cycle). This switching process can reduce or regulate the voltage at the DC connection, which could otherwise become undesirably high while the motor is running. 30 continues to slow down or decelerate. The reduction or control of the DC connection voltage can be partially achieved through the operation of the switching devices. 52 – 62 inherent “switching losses” are caused, as is known to experts.

[0034] A dead-time compensation algorithm can be applied to the switching operation to further increase or otherwise adjust the reduction rate of the DC connection voltage. As is generally known, dead-time compensation algorithms are used during normal, active operation of vehicle drive motors to compensate for the relative delays in current flow caused by the time required by the switching devices (e.g., switching devices). 52 – 62 ) are needed to switch between operating states.

[0035] In one embodiment, the dead-time compensation algorithm can adjust the switching operation during a delay in such a way that the operating cycles of both the up-switching devices 52 – 56 as well as the low-voltage switching devices 58 – 62For example, the voltage can vary between 47% and 53% (while still maintaining approximately a 50 / 50 split between the first and second operating modes). Adjustments made to the switching operation can be based on the detected DC link voltage, which can be monitored by the inverter control module (or electronic control system), as it may be desirable to reduce the DC link voltage to a specific rate.

[0036] The process can end if, for example, the DC connection voltage is reduced below a predetermined threshold, which may be between 60 and 70 volts, or if the motor stops turning.

[0037] One advantage of the system and method described above is that the DC connection voltage can be regulated during motor deceleration. As a result, braking torque or motor braking torque can still be applied to the motor while the DC connection voltage is reduced to a desired level.

[0038] Other embodiments can utilize various source devices for the DC / AC inverters, such as DC / DC converters, and various load devices for the electric motors, such as batteries (e.g., lithium-ion batteries). The system described above can be implemented in systems different from automobiles, such as marine or aviation vehicles. The electric motor and the energy inverter can have different numbers of phases, such as two or four. Other types of energy sources can be used, such as current sources and loads including diode rectifiers, thyristor converters, fuel cells, inductors, capacitors, and / or any combination thereof. It should be noted that the numerical ranges provided above are intended only as examples and are not meant to limit the use of the system described above.

[0039] While at least one exemplary embodiment has been presented in the preceding detailed description, it is preferred that a large number of variations exist. It is also preferred that the exemplary embodiment or embodiments are merely examples and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the preceding detailed description is intended to provide the person skilled in the art with helpful guidance for carrying out the exemplary embodiment or embodiments. It is assumed that various modifications regarding the function and arrangement of the elements can be made without departing from the scope of the invention as defined in the appended claims and their legal equivalents. Further embodiment 1. Method for operating an inverter with a plurality of high-switching devices and a plurality of low-switching devices coupled to an electric motor, the method comprising: Detecting a condition indicating a delay in the electric motor; and Switching the inverter between a first operating mode and a second operating mode during the deceleration of the electric motor, wherein in the first operating mode each switching device is activated by the majority of high switching devices and each switching device is deactivated by the majority of low switching devices, wherein in the second operating mode each switching device is activated by the majority of low switching devices and each switching device is deactivated by the majority of high switching devices. 2. Method according to embodiment 1, wherein switching the inverter between the first operating mode and the second operating mode comprises: Disabling each switching device from the majority of high-voltage switching devices; and Activating each switching device from the majority of low switching devices after deactivating each switching device from the majority of high switching devices. 3. Method according to embodiment 2, wherein switching the inverter between the first operating mode and the second operating mode further comprises: Disabling each switching device from the majority of low-level switching devices; and Activating each switching device from the majority of high switching devices after deactivating each switching device from the majority of low switching devices. 4. Method according to embodiment 2, wherein the plurality of high-switching devices and the plurality of low-switching devices together comprise a plurality of pairs of switching devices, each pair of switching devices comprising one switching device from the plurality of high-switching devices and one switching device from the plurality of low-switching devices. 5. Method according to embodiment 4, wherein each switching device of the plurality of high-switching devices and each switching device of the plurality of low-switching devices comprises a first terminal and a second terminal, wherein in each pair of switching devices of the plurality of pairs of switching devices the second terminal of the corresponding high-switching device is connected to the first terminal of the corresponding low-switching device. 6. Method according to embodiment 5, wherein the inverter and the electric motor are arranged such that switching the inverter between the first and second operating modes causes a voltage drop at the first terminals from the majority of high-switching devices and at the second terminals from the majority of low-switching devices. 7. Method according to embodiment 6, further comprising: Monitoring the voltage at the first terminals of most high-voltage switching devices and at the second terminals of most low-voltage switching devices; and Adapting the switching of the inverter between the first and second operating modes based on monitoring the voltage at the first terminals of the majority of high-switching devices and at the second terminals of the majority of low-switching devices, and based on a dead-time compensation algorithm. 8. Method according to embodiment 6, wherein switching the inverter between first and second operating modes comprises operating the inverter in the first and second operating modes for approximately equal time periods. 9. Method according to embodiment 6, wherein the electric motor comprises a plurality of windings, wherein the plurality of windings is electrically connected between the second terminal of the high switching device and the first terminal of the low switching device of a corresponding pair of the plurality of pairs of switching devices. 10. Method according to embodiment 6, wherein the inverter further comprises a plurality of diodes, the plurality of diodes being arranged in an antiparallel configuration with a corresponding switching device consisting of a plurality of high-switching devices and a plurality of low-switching devices. 11. Method for operating an inverter with a plurality of pairs of switching devices, wherein each pair of the plurality of pairs of switching devices comprises a high switching device and a low switching device coupled to a vehicle drive motor, the method comprising: Detecting a condition indicating a delay in the vehicle's drive motor; and Switching the inverter between a first operating mode and a second operating mode during the deceleration of the electric motor for approximately equal time periods, wherein in the first operating mode each switching device is activated by the high switching devices of the plurality of pairs of switching devices and each switching device is deactivated by the low switching devices of the plurality of pairs of switching devices, and wherein in the second operating mode each switching device is activated by the low switching devices of the plurality of pairs of switching devices and each switching device is deactivated by the high switching devices of the plurality of pairs of switching devices. 12. Method according to embodiment 11, wherein each switching device of the high switching devices and each switching device of the low switching device of the plurality of pairs of switching devices comprises a first terminal and a second terminal, and wherein within each pair of the plurality of pairs of switching devices the second terminal of the corresponding high switching device is connected to the first terminal of the corresponding low switching device. 13. Method according to embodiment 12, wherein the inverter and the electric motor are arranged such that switching the inverter between the first and second operating modes causes a decrease in voltage at the first terminals of the high-switching devices of the plurality of pairs of switching devices and at the second terminals of the low-switching devices of the plurality of pairs of switching devices. 14. Method according to embodiment 13, further comprising: Monitoring the voltage at the first terminals of the high-voltage switching devices of the majority of switching device pairs and at the second terminals of the low-voltage switching devices of the majority of switching device pairs; and Adapting the switching of the inverter between the first and second operating modes based on monitoring the voltage at the first terminals of the high switching devices of the majority of pairs of switching devices and at the second terminals of the low switching devices of the majority of pairs of switching devices. 15. Method according to embodiment 14, wherein the inverter further comprises a plurality of diodes, wherein the plurality of diodes are arranged in an anti-parallel configuration with a corresponding switching device consisting of the high switching devices of the plurality of pairs of switching devices and the low switching devices of the plurality of pairs of switching devices. 16. Vehicle propulsion system, including: an electric motor with multiple windings; a direct current to alternating current (DC / AC) energy inverter with a plurality of pairs of power switching devices coupled to the plurality of windings, each pair of power switching devices comprising a high-power switching device and a low-power switching device; a processor system in operational communication with the electric motor and the DC / AC energy inverter, wherein the processor is configured for this purpose to detect a condition indicating a delay in the electric motor; and to switch the operation of the DC / AC energy inverter between a first operating mode and a second operating mode during the deceleration of the electric motor, wherein in the first operating mode the high-power switching devices are activated by the majority of pairs of power switching devices and the low-power switching devices are deactivated by the majority of pairs of switching devices, wherein in the second operating mode the low-power switching devices are activated by the majority of pairs of power switching devices and the high-power switching devices are deactivated by the majority of pairs of power switching devices. 17. Vehicle drive system according to embodiment 16, wherein the processor system is configured such that switching the operation of the DC / AC energy inverter between the first operating mode and the second operating mode includes operating the DC / AC energy inverter in the first operating mode and the second operating mode for substantially equal time periods. 18. Vehicle drive system according to embodiment 17, wherein each switching device of the high-power switching devices and each switching device of the low-power switching devices of the plurality of pairs of power switching devices comprises a first terminal and a second terminal, wherein in each switching device of the plurality of pairs of power switching devices the second terminal of the corresponding high-power switching device is connected to the first terminal of the corresponding low-power switching device, and wherein the DC / AC energy inverter and the electric motor are configured such thatthat switching the inverter between the first and second operating modes causes a voltage drop at the first terminals of the high-power switching devices of the majority of pairs of power switching devices and at the second terminals of the low-power switching devices of the majority of pairs of power switching devices. 19. Vehicle drive system according to embodiment 18, wherein the processor system is further configured: to monitor the voltage at the first terminals of the high-power switching devices of the majority of pairs of switching devices and at the second terminals of the low-power switching devices of the majority of pairs of switching devices; and to adapt the switching of the inverter between the first and second operating modes based on monitoring the voltage at the first terminals of the high-power switching devices of the majority of pairs of power switching devices and at the second terminals of the low-power switching devices of the majority of pairs of power switching devices. 20. Vehicle propulsion system according to embodiment 19, wherein the DC / AC energy inverter further comprises a plurality of diodes, the plurality of diodes being arranged in an antiparallel configuration with a corresponding switching device from the high-power switching devices and the low-power switching devices from the plurality of pairs of power switching devices.

Claims

[1] Method for operating an inverter with a plurality of high-switching devices and a plurality of low-switching devices coupled to an electric motor, the method comprising: Detecting a condition indicating a delay in the electric motor; and Switching the inverter between a first operating mode and a second operating mode during the deceleration of the electric motor, wherein in the first operating mode each switching device is activated by the majority of high switching devices and each switching device is deactivated by the majority of low switching devices, wherein in the second operating mode each switching device is activated by the majority of low switching devices and each switching device is deactivated by the majority of high switching devices. [2] Method according to claim 1, wherein the switching of the inverter between the first operating mode and the second operating mode comprises Disabling each switching device from the majority of high-voltage switching devices; and Activating each switching device from the majority of low switching devices after deactivating each switching device from the majority of high switching devices. [3] Method according to any of the preceding claims, wherein switching the inverter between the first operating mode and the second operating mode further comprises: Disabling each switching device from the majority of low-level switching devices; and Activating each switching device from the majority of high switching devices after deactivating each switching device from the majority of low switching devices. [4] Method according to any of the preceding claims, wherein the plurality of high-switching devices and the plurality of low-switching devices together comprise a plurality of pairs of switching devices, each pair of switching devices comprising a switching device from the plurality of high-switching devices and a switching device from the plurality of low-switching devices. [5] Method according to any of the preceding claims, wherein each switching device of the plurality of high-switching devices and each switching device of the plurality of low-switching devices comprises a first terminal and a second terminal, wherein in each pair of switching devices of the plurality of pairs of switching devices the second terminal of the corresponding high-switching device is connected to the first terminal of the corresponding low-switching device. [6] Method according to one of the preceding claims, wherein the inverter and the electric motor are arranged such that switching the inverter between the first and second operating modes causes a voltage drop at the first terminals from the plurality of high-switching devices and at the second terminals from the plurality of low-switching devices. [7] Method according to any of the preceding claims, further comprising: Monitoring the voltage at the first terminals of most high-voltage switching devices and at the second terminals of most low-voltage switching devices; and Adapting the switching of the inverter between the first and second operating modes based on monitoring the voltage at the first terminals of the majority of high-switching devices and at the second terminals of the majority of low-switching devices, and based on a dead-time compensation algorithm. [8] Vehicle propulsion system, comprising: an electric motor with a plurality of windings, a direct current to alternating current (DC / AC) energy inverter with a plurality of pairs of power switching devices coupled to the plurality of windings, each pair of power switching devices comprising a high-power switching device and a low-power switching device; a processor system in operational communication with the electric motor and the DC / AC energy inverter, wherein the processor is configured for this purpose to detect a condition indicating a delay in the electric motor; and to switch the operation of the DC / AC energy inverter between a first operating mode and a second operating mode during the deceleration of the electric motor, wherein in the first operating mode the high-power switching devices are activated by the majority of pairs of power switching devices and the low-power switching devices are deactivated by the majority of pairs of switching devices, wherein in the second operating mode the low-power switching devices are activated by the majority of pairs of power switching devices and the high-power switching devices are deactivated by the majority of pairs of power switching devices. [9] Vehicle drive system according to claim 8, wherein the processing system is configured such that switching the operation of the DC / AC energy inverter between the first operating mode and the second operating mode comprises operating the DC / AC energy inverter in the first operating mode and the second operating mode for substantially equal time periods. [10] Vehicle propulsion system according to claim 8 or 9, wherein each switching device of the high-power switching devices and each switching device of the low-power switching devices of the plurality of pairs of power switching devices comprises a first terminal and a second terminal, wherein in each switching device of the plurality of pairs of power switching devices the second terminal of the corresponding high-power switching device is connected to the first terminal of the corresponding low-power switching device, and wherein the DC / AC power inverter and the electric motor are configured such thatthat switching the inverter between the first and second operating modes causes a voltage drop at the first terminals of the high-power switching devices of the majority of pairs of power switching devices and at the second terminals of the low-power switching devices of the majority of pairs of power switching devices.

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