Method for controlling a device having an electrically-driven or -assisted turbo or compressor

Abstract

The present disclosure relates to a method for controlling a device comprising an electric motor (EM) for assisting a turbo-compressor (TTB) or a compressor (TCP), the method comprising: acquiring first and second operating parameters of the electric motor and controlling the electric motor to maintain constant the first operating parameter according to a set-point value of the first operating parameter; measuring a variation frequency of the second operating parameter; comparing an amplitude of the variation frequency to a surge threshold (STH); and when the amplitude of the variation frequency exceeds the surge threshold, triggering a corrective action to set the amplitude of the variation frequency below the surge threshold, wherein the first and second operating parameters are respectively a rotation speed of the electric motor and a torque of the electric motor or a current flowing through the electric motor, or reversely.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of systems for boosting combustion engines, specifically with an electric motor connected to a turbo or a compressor. The present invention can be applied in heavy-duty vehicles, such as trucks, buses, and construction equipment. However, the present disclosure is not restricted to any particular vehicle.BACKGROUND

[0002] Modern combustion engines are using a compressor for boosting the engine having a large flow width. This is the case for all types of boosted standard internal combustion engine (ICE) regardless of the type of engine (otto, diesel, etc.) or fuel (diesel, petrol, gaseous fuels like compressed natural gas - CNG -, or hydrogen, etc.). Generally, the engines stretch their demand on the boosting system up to the limit. This makes traditional boosting systems insufficient to meet the requirements, limiting the engine performance. One of the limitations results from surge in the turbo compressor. Surge is a dynamic instability that occurs in turbo-compressors. Surge is limiting low flow, i.e. lowest possible flow at a given pressure ratio, for the compressor. As the flow through a compressor is reduced, a point is reached where the flow pattern becomes unstable. Surge happens quickly, and conventional instruments usually fail to recognize the effects of surge. In the same way, conventional actuators and valves often fail to prevent it.

[0003] However, an especially high demand for boosted engines is expected for the coming hydrogen spark ignition (SI) engines, where high air flow is needed to avoid knocks and NOx emissions.

[0004] Engines have varying operating conditions such as ambient pressure, temperature and different flow demand depending on the engine state (cold start, transient operation etc.). In addition, it can be observed that individual variance are always present for the engine system components and also the engine installation in the vehicle, which influence flow (the boundaries). For example, small differences in bearing friction or aerodynamic performance of the compressor and / or turbines will lead to different operating points in identical compressors of different engines. In addition, the packaging around the engine may have constraints that provide different conditions including variations in cylinder behavior (volumetric efficiency) and combustion in different trucks having same engine specifications. Close to surge, a small difference in speed and / or compressor shaft torque can make a difference between surge or not. For that reason, traditional turbo systems need to have a surge margin implemented, typically, at least, about 10% in flow distance to the surge line in the compressor map for the turbocharger.

[0005] Today for a turbo-compressor system, the matching is very conservative to avoid surge in all conditions which reduce the system (compressor) operating range. Other solutions, sometimes used in component testing, are not very feasible for a production implementation due to both cost, complexity, robustness, and thus accuracy would be sacrificed for an affordable robust production solution.

[0006] Generally, a compressor map is used with a surge line for an average compressor in combination with air flow measurement. Another solution is to use temperature or pressure measurement on the compressor inlet. However, this solution is not feasible in a real application.

[0007] Valve systems, sensors etc. are sometimes used to avoid surge (flow recirculation or blow-off). Such solutions are complex, bulky and also slow. Thus, current solutions avoid surge too slowly or in an inaccurate and ineffective manner.

[0008] Therefore, there is a need to avoid surge risks in a compressor of a combustion engine, specifically with an electric motor connected to the turbo compressor. There is a need to avoid surges in a fast and accurate manner, and without requiring any additional hardware.SUMMARY

[0009] The present disclosure is related to a method for controlling a device comprising an electric motor for assisting a turbo-compressor or a compressor, the method comprising: simultaneously acquiring first and second operating parameters of the electric motor and controlling the electric motor to maintain constant the first operating parameter according to a set-point value of the first operating parameter; measuring a variation frequency of the second operating parameter; comparing an amplitude of the variation frequency to a surge threshold; and when the amplitude of the variation frequency of exceeds the surge threshold, triggering a corrective action to set the amplitude of the variation frequency below the surge threshold, wherein the first and second operating parameters are respectively a rotation speed of the electric motor and a torque of the electric motor or a current flowing through the electric motor, or reversely.

[0010] In this manner, the surges that can arise in the compressor are avoided. Such a compressor surge avoidance is achieved while allowing the use of a wider area of the compressor operating map without surge risk. In addition, the method can be implemented without requiring additional hardware.

[0011] According to an embodiment, the corrective action is performed by decreasing the set-point value of the first operating parameter, or by setting the second operating parameter to a lower value.

[0012] Thus the compressor surges can be easily and quickly avoided.

[0013] According to an embodiment, the method further comprises filtering the variation frequency of the second operating parameter before comparing it to the surge threshold, the filtering being performed by means of a low-pass filter having a cutoff frequency lower than 15 Hz.

[0014] Thanks to the use of such a low-pass filter, the surge detection is more reliable.

[0015] According to an embodiment, the method further comprises filtering the variation frequency of the second operating parameter before comparing it to the surge threshold, the filtering being performed by means of an active band-pass filter having a bandwidth adjusted as a function of a turbo wheel speed.

[0016] Thanks to the use of such an active band-pass filter, the surge detection can be adapted to the turbo wheel speed on which the surge frequency depends. Thus the surge detection can be more accurate when using such an active filter and a much wider area of the compressor operating map can be used without surge risk.

[0017] According to an embodiment, the method further comprises adjusting the surge threshold to a turbo wheel speed.

[0018] Thanks to such an adjustment, the surge detection can be adapted to the turbo wheel speed on which the surge frequency depends. Thus, the surge detection can be more accurate and a much wider area of the compressor operating map can be used without surge risk.

[0019] According to an embodiment, the rotation speed of the electric motor is measured from command signals controlling an inverter feeding the electric motor.

[0020] The inverter command signals are already available to the vehicle control unit ECU. Therefore, such measurement does not need any additional hardware such as sensors.

[0021] According to an embodiment, the rotation speed of the electric motor is adjusted by adjusting command signals controlling an inverter feeding the electric motor.

[0022] Such a control of the rotation speed of the electric motor does not need any additional hardware.

[0023] According to an embodiment, the torque or current flowing through the electric motor is adjusted by adjusting command signals controlling an inverter feeding the electric motor.

[0024] Embodiments may also relate to a system for controlling a device comprising an electric motor for assisting a turbo or a compressor, the system comprising processing circuitry configured to implement the method as above-defined.

[0025] Embodiments may also relate to a vehicle comprising a turbo or a compressor, an electric motor for assisting a turbo or compressor and a system as above-defined.

[0026] According to an embodiment, the vehicle further comprises an internal combustion engine.

[0027] According to an embodiment, the vehicle further comprises a fuel cell.

[0028] Embodiment may also relate to a computer program product comprising program code for performing, when executed by a processing circuitry, the method as above-defined.

[0029] Embodiment may also relate to a non-transitory computer-readable storage medium comprising instructions, which when executed by a processing circuitry, cause the processing circuitry to perform the method as above-defined.BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The foregoing and other purposes, features, aspects and advantages of the invention will become apparent from the following detailed description of embodiments, given by way of illustration and not limitation, with reference to the accompanying drawings, in which the same reference refer to similar elements or to elements having similar functions, and in which: Figure 1 is an exemplary illustration of a vehicle according to one example; Figure 2 is an exemplary illustration of an engine system of a vehicle according to one example; Figure 3 is an exemplary illustration of a motor controller of an electric motor according to one example; Figure 4 is an exemplary illustration of a motor control function of the electric motor according to one example; Figure 5 is an exemplary illustration of a compressor map according to one example; and Figure 6 is a schematic diagram of an exemplary computer system for implementing examples disclosed herein, according to one example. DETAILED DESCRIPTION

[0031] Aspects set forth below represent the necessary information to enable those skilled in the art to practice the inventive concept. The inventive concept may seek to improve an overall efficiency of an engine system with a turbo arrangement. A technical benefit may include that surge may be avoided for the compressor of turbo arrangements.

[0032] Figure 1 is an exemplary illustration of a vehicle 1 according to one example. The vehicle 1 in Figure 1 is exemplified as a truck, but the below described inventive concept may be provided in other vehicles, such as e.g. working machines, buses, cars, etc. The vehicle 1 comprises an internal combustion engine 10. The internal combustion engine 10 is a gasoline or hydrogen internal combustion engine. In such case, the hydrogen internal combustion engine receives hydrogen gas for combustion in one or more combustion chambers. As will be evident from the below description, the vehicle 1 further comprises an engine system 100 connected to the internal combustion engine 10. The engine system 100 also comprises a control unit ECU. The control unit ECU comprises a processor device configured to control the engine system 100 as will be described in further detail below.

[0033] Figure 2 shows an exemplary illustration of the engine system 100 according to one example. As can be seen, the engine system 100 is connected to the internal combustion engine 10. The exemplified internal combustion engine 10 comprises e.g. six combustion chambers 14, an inlet manifold 16 and an exhaust manifold 18. Air is thus fed into the inlet manifold 16, and combustion gas is exhausted to the engine system 100 via the exhaust manifold 18.

[0034] The engine system 100 comprises a turbo arrangement comprising a turbine TTB which is connected in downstream fluid communication with the exhaust manifold 18. Accordingly, the turbine TTB receives combustion gases exhausted from the internal combustion engine 10. The turbo arrangement further comprises a compressor TCP operably connected to the turbine TTB. In particular, a turbo shaft 112 is connecting the turbine TTB and the compressor TCP to each other. The turbine TTB is operated to rotate by the flow of combustion gases it receives, whereby the compressor TCP rotates to pressurize a flow of air 114 fed into an inlet of the compressor TCP. In addition to the flow of combustion gases exposing the turbo arrangement to achieve a rotational motion, the rotation of the turbo shaft 112 can be controlled to increase and / or decrease by other means than the flow of combustion gases from the internal combustion engine 10. For example, the rotation can be controlled by controlling the flow of exhaust gases fed to the turbo arrangement, such as e.g. by means of bypass valve, or by using a variable turbo geometry (VTG). The rotation may also be controlled mechanically by a variable gear ratio.

[0035] Preferably, and according to an example, the turbo arrangement 102 comprises an electric machine EM configured to control the rotational speed of turbo shaft 112. The turbo arrangement may thus be referred to as an electrically controlled turbo arrangement. According to an example, the electric machine EM is arranged between the turbine TTB and the compressor TCP, i.e. the electric machine EM is arranged in, or constitutes, the turbo shaft 112. Such electric machine EM preferably comprises a rotor and a stator.

[0036] The electric machine EM is controlled by a motor control circuit MCTL which is connected to the above described control unit ECU. Thus, the processor device of the control unit ECU is configured to control the rotational speed of the turbo arrangement via the control circuit MCTL. The electric machine EM is also preferably connected to an energy storage 150, preferably a battery, in order to receive electric power for its propulsion.

[0037] The combustion gas 155 from the turbine TTB flow towards an ambient environment. The flow of air 114 entering the compressor TCP is pressurized and fed downstream the compressor TCP into the inlet manifold 16 of the internal combustion engine. A charge air cooler CAC can be provided to cool the air downstream the compressor TCP. Before entering the compressor TCP, the flow of air 114 can pass through an air filter AFL.

[0038] The electric machine EM can be controlled by the motor control circuit MCTL shown in Figure 3, according to an example. The control circuit MCTL comprises an inverter IVT and a control unit MCU. In the example of Figure 3, the electric machine EM is a permanent magnet motor or a permanent magnet synchronous motor controlled by a three-phase inverter. The three phases are driven by three half-bridges, for a total of six power transistors which are controlled by PWM (Pulse-Width Modulated) signals, whose timing and sequence are controlled by the unit MCU, on the basis on a position of the rotor of the motor EM provided by a position encoder PENC. The unit MCU receives from the inverter IVT current intensities and voltages of one or more of the three phases. In addition, the unit MCU is linked to the position encoder PENC by an encoder interface EINT providing to the unit MCU digital values of the instant rotor positions measured by the position encoder PENC. However, the unit MCU can be configured to estimate the position of the rotor of the motor EM using the motor's back-emf (electromotive force). The rotation speed of the rotor can be estimated from the variations of the rotor position. The rotation speed of the rotor can be estimated from the signals ICS controlling the inverter IVT especially when the electrical motor EM is a permanent magnet motor.

[0039] The engine system 100 with the above-described turbo arrangement can efficiently improve pulse utilization of the engine system to thereby improve an overall efficiency of the engine system 100. However, there is a risk that the compressor TCP is exposed to a phenomenon commonly referred to as surge.

[0040] Figure 4 represents a motor control function performed by the control unit ECU. The motor control function comprises a control closed loop MCLF configured to fulfill air demand from the combustion engine 10, a measurement function ECM, frequency filters CFF and a surge control function SCTL. The control closed loop MCLF receives an air demand from the combustion engine 10 and determines a set-point value a first operating parameter of the electric motor EM based on the air demand. The control closed loop MCLF further receives measured values of the first operating parameter and a second operating parameter from the motor control circuit MCTL. The control closed loop MCLF is further configured to hold the first parameter at the set-point value by adjusting the second operating parameter according to a control closed loop. The first and second operating parameters are respectively the current intensity value flowing through the inverter IVT (or torque provided by the motor EM), and the motor rotation speed, or reversely.

[0041] The measurement function ECM receives from the control closed loop MCLF values of the second operating parameter and provides from these values a digital frequency signal SG representing the frequency of the second parameter. The frequency signal can be obtained using a Fourier transform applied to the variations of second operating parameter. The frequency signal is filtered by a low-pass filter and / or band-pass filter of the frequency filters CFF. The amplitude of the filtered frequency signal is compared with a surge threshold STH. If the amplitude of the filtered frequency signal FSG is greater than the threshold STH, the surge control function SCTL is activated to compute a surge factor reduction SFR which is provided to the control closed loop MCLF. The control closed loop MCLF reduces the set-point value of the first parameter as a function of the surge factor reduction SFR, to set the variation frequency of the first parameter below the surge threshold. Typically, the frequency of the first or second parameters are lower than 10 Hz (or 15 Hz for small radial turbo-compressors). Thus the low-pass filter to be used can have a cutoff frequency lower than 15 Hz.

[0042] Figure 5 is an exemplary illustration of a compressor map according to one example. The compressor map is preferably predefined and may be designed from compressor rig tests and / or predicted or estimated from simulations. The compressor map may be provided to the processor device of the control unit ECU. The compressor map 300 defines an area 302 in which a compressor is operated to increase the pressure of the air upstream the combustion engine 10. The vertical axis 304 represent the pressure, or the pressure ratio, and the horizontal axis 306 represents the mass flow. The area 302 is delimited by a surge line 310 and a choke line 312. Curves 305 ranging from 27 krpm to 130 krpm represent positions where the turbo compressor speed is constant. Lines 306 ranging from 60 to 83 represent positions where the compressor efficiency expressed in percentage is constant.

[0043] When the pressure ratio vs. mass flow of the compressor TCP approaches the surge line 310 there is a risk that the compressor flow will stall. When the pressure vs. mass flow of the compressor approaches the choke line 312, the compressor will choke, reducing the efficiency of the combustion engine 10.

[0044] During operation of the above-described engine system 100, the processor device of the control unit ECU determines a pressure and a mass flow of the air 114 pressurized by the compressor TCP. The processor device can hereby determine a compressor map position 320, i.e. an instant compressor map position of the compressor TCP. In the example of Figure 5, the compressor map position 320 is located close to the surge line 310. In detail, a distance between the compressor map position 320 and the surge line 310 may be below a predetermined threshold distance.

[0045] According to an embodiment, surges are prevented from arising by using the phenomenon of pressure and mass flow fluctuation in the compressor TCP when the operation in the compressor map is close to (or at) surge. Prior to surge, periodical reductions and accelerations of the flow can be observed in the compressor TCP. When at surge, the flow in the compressor TCP is completely stalled and it can even be reversed for a short period of time. The surge phenomenon results in varying mass flow already at some distance to the surge line 310, which in turn results in a varying (fluctuating) compressor power. Since the electric motor EM is directly connected to the compressor TCP, the fluctuation immediately is transferred into a change both the speed and torque of the electric motor EM. In fact, the torque is directly related to the current in the motor.

[0046] Therefore, the speed and the current of the electric motor EM are operating parameters that can be used to detect surges in the compressor TCP. The operating parameters of the electric motor EM to be used depend on a control mode implemented to prevent surges. Thus the processor device of the control unit ECU can implement a first control mode in which the electric motor EM is controlled to hold its speed constant. This results in fluctuations of the torque provided by the electric motor EM, or the currents flowing within the inverter IVT. Therefore, in the first control mode, the current in the inverter IVT is measured and provided to the control unit ECU to detect oscillations, such oscillations indicating that the compressor TCP is close to surge.

[0047] Thus the processor device of the control unit ECU can implement a second control mode in which the electric motor EM is controlled to hold its torque constant. Thus the current in the inverter IVT is held constant. This results in fluctuations of the rotation speed of the electric motor EM. Therefore, in the second control mode, the rotation speed of the electric motor EM is measured to detect oscillations, such oscillations indicating that the compressor TCP is close to surge.

[0048] The band-pass filters CFF can be used to filter out the rotation speed or torque signal noise to get a more reliable surge detection.

[0049] For both modes, the higher the fluctuation of the measured signal, the closer to surge the compressor is operating. For a better detection, this signal can be calibrated for each control mode. In addition, the measured signal can be transformed in a percent from a means value of the signal.

[0050] The surge limit or threshold STH can be defined for every specific use case and control mode. In some applications, for example, a transient operation could be set more aggressive, so that a larger fluctuation of the torque or rotation speed can be accepted for a shorter time. The surge threshold STH can also be set depending on a running mode of the combustion engine 10 (cold start, fuel consumption mode, Eco Mode, etc.).

[0051] In Figure 5, a surge event can be detected when approaching the surge line 310 in the compressor map 300. The surge detection threshold STH can be set for example to trigger a corrective action when the compressor TCP operating conditions are located at operating point P1, the corrective action setting the compressor to the operating conditions corresponding to a point P2 located farther from the surge line 310. The corrective action comprises controlling the rotor rotation speed or the torque of the electric motor EM to force the compressor TCP to reach the operating point P2 in the compressor map 300.

[0052] According to an embodiment, an active band-pass filter having a bandwidth depending on the turbo wheel speed (TWS) is used to improve accuracy of the surge detection. This is very effective, since the amplitude of the surge frequency variation may vary with TWS.

[0053] According to another embodiment, the accuracy of the surge detection can also be improved by adjusting the surge threshold STH based on the turbo wheel speed.

[0054] Turning finally to Fig. 6 which is a schematic diagram of a computer system CSYS for implementing examples disclosed herein. The computer system CSYS is adapted to execute instructions from a computer-readable medium to perform these and / or any of the functions or processing described herein. The computer system CSYS may be connected (e.g., networked) to other machines in a LAN, an intranet, an extranet, or the Internet. While only a single device is illustrated, the computer system CSYS may include any collection of devices that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. Accordingly, any reference in the disclosure and / or claims to a computer system, computing system, computer device, computing device, control system, control unit, electronic control unit (ECU), processor device, etc., includes reference to one or more such devices to individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. For example, control system may include a single control unit or a plurality of control units connected or otherwise communicatively coupled to each other, such that any performed function may be distributed between the control units as desired. Further, such devices may communicate with each other or other devices by various system architectures, such as directly or via a Controller Area Network (CAN) bus, etc.

[0055] The computer system CSYS may comprise at least one computing device or electronic device capable of including firmware, hardware, and / or executing software instructions to implement the functionality described herein. The computer system CSYS may include a processor device PRC (may also be referred to as a control unit), a memory MEM, and a system bus SBS. The computer system CSYS may include at least one computing device having the processor device PRC. The system bus SBS provides an interface for system components including, but not limited to, the memory MEM and the processor device PRC. The processor device PRC may include any number of hardware components for conducting data or signal processing or for executing computer code stored in memory MEM. The processor device PRC (e.g., control unit) may, for example, include a general-purpose processor, an application specific processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a circuit containing processing components, a group of distributed processing components, a group of distributed computers configured for processing, or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The processor device may further include computer executable code that controls operation of the programmable device.

[0056] The system bus SBS may be any of several types of bus structures that may further interconnect to a memory bus (with or without a memory controller), a peripheral bus, and / or a local bus using any of a variety of bus architectures. The memory MEM may be one or more devices for storing data and / or computer code for completing or facilitating methods described herein. The memory MEM may include database components, object code components, script components, or other types of information structure for supporting the various activities herein. Any distributed or local memory device may be utilized with the systems and methods of this description. The memory MEM may be communicably connected to the processor device PRC (e.g., via a circuit or any other wired, wireless, or network connection) and may include computer code for executing one or more processes described herein. The memory MEM may include non-volatile memory NVM (e.g., read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), etc.), and volatile memory VM (e.g., random-access memory (RAM)), or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a computer or other machine with a processor device PRC. A basic input / output system (BIOS) ISW may be stored in the non-volatile memory NVM and can include the basic routines that help to transfer information between elements within the computer system CSYS.

[0057] The computer system CSYS may further include or be coupled to a non-transitory computer-readable storage medium such as the storage device 714, which may comprise, for example, an internal or external hard disk drive (HDD) (e.g., enhanced integrated drive electronics (EIDE) or serial advanced technology attachment (SATA)), HDD (e.g., EIDE or SATA) for storage, flash memory, or the like. The storage device STD and other drives associated with computer-readable media and computer-usable media may provide non-volatile storage of data, data structures, computer-executable instructions, and the like. A number of modules can be implemented as software and / or hard-coded in circuitry to implement the functionality described herein in whole or in part. The modules may be stored in the storage device STD and / or in the volatile memory VM, which may include an operating system OPS and / or one or more program modules APS. All or a portion of the examples disclosed herein may be implemented as a computer program product CPP stored on a transitory or non-transitory computer-usable or computer-readable storage medium (e.g., single medium or multiple media), such as the storage device STD, which includes complex programming instructions (e.g., complex computer-readable program code) to cause the processor device PRC to carry out the steps described herein. Thus, the computer-readable program code can comprise software instructions for implementing the functionality of the examples described herein when executed by the processor device PRC. The processor device PRC may serve as a controller or control system for the computer system CSYS that is to implement the functionality described herein.

[0058] The computer system CSYS also may include an input device interface IID (e.g., input device interface and / or output device interface). The input device interface IID may be configured to receive input and selections to be communicated to the computer system CSYS when executing instructions, such as from a keyboard, mouse, touch-sensitive surface, etc. Such input devices may be connected to the processor device PRC through the input device interface IID coupled to the system bus SBS but can be connected through other interfaces such as a parallel port, an Institute of Electrical and Electronic Engineers (IEEE) 1394 serial port, a Universal Serial Bus (USB) port, an IR interface, and the like. The computer system CSYS may include an output device interface OlD configured to forward output, such as to a display, a video display unit (e.g., a liquid crystal display, LCD, or a cathode ray tube, CRT). The computer system CSYS may also include a communications interface CMC suitable for communicating with a network as appropriate or desired.

[0059] The above description of various embodiments is provided for purpose of description to one of ordinary skills in the related art. It is not intended to be exhaustive or to limit the scope of the present disclosure solely to the disclosed embodiments. Numerous alternatives or variations to the present disclosure will be apparent to those of ordinary skills in the related art. Accordingly, while some alternatives or embodiments have been presented specifically, other embodiments will be apparent or easily developed by those of ordinary skills in the related art. Limitations in the appended claims should be interpreted broadly based on the language used in the claims and such limitations should not be restricted to the specific examples described above.

[0060] In this respect, it is apparent to those of ordinary skills in the related art that the above-disclosed surge control can also be applied to fuel cells that use an electrically-driven or -assisted turbo or compressor.

[0061] The above-disclosed surge control can also be applied to different types of engine systems or vehicles having an electrically-assisted turbo or compressor, and more generally to traditional internal combustion engine vehicles with an additional generator capacity to control and drive an electrically-assisted turbo or booster.

[0062] The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms "comprises", "comprising", "includes" and / or "including" when used herein specify the presence of stated features, integers, actions, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, actions, steps, operations, elements, components, and / or groups thereof.

[0063] It will be understood that, although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of the present disclosure.

[0064] It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.

[0065] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Claims

1. A method for controlling a device comprising an electric motor (EM) for assisting a turbo-compressor (TTB) or a compressor (TCP), the method comprising: simultaneously acquiring first and second operating parameters of the electric motor and controlling the electric motor to maintain constant the first operating parameter according to a set-point value of the first operating parameter; measuring a variation frequency of the second operating parameter; comparing an amplitude of the variation frequency to a surge threshold (STH); and when the amplitude of the variation frequency of exceeds the surge threshold, triggering a corrective action to set the amplitude of the variation frequency below the surge threshold, wherein the first and second operating parameters are respectively a rotation speed of the electric motor and a torque of the electric motor or a current flowing through the electric motor, or reversely.

2. The method according to claim 1, wherein the corrective action is performed by decreasing the set-point value of the first operating parameter, or by setting the second operating parameter to a lower value.

3. The method according to claim 1 or 2, further comprising filtering the variation frequency of the second operating parameter before comparing it to the surge threshold (STH), the filtering being performed by means of a low-pass filter (CFF) having a cutoff frequency lower than 15 Hz.

4. The method according to any one of claims 1 to 3, further comprising filtering the variation frequency of the second operating parameter before comparing it to the surge threshold (STH), the filtering being performed by means of an active band-pass filter (CFF) having a bandwidth adjusted as a function of a turbo wheel speed.

5. The method according to any one of claims 1 to 4, further comprising adjusting the surge threshold (STH) to a turbo wheel speed.

6. The method according to any one of claims 1 to 5, wherein the rotation speed of the electric motor (EM) is measured from command signals (ICS) controlling an inverter (IVT) feeding the electric motor.

7. The method according to any one of claims 1 to 6, wherein the rotation speed of the electric motor (EM) is adjusted by adjusting command signals (ICS) controlling an inverter (IVT) feeding the electric motor.

8. The method according to any one of claims 1 to 7, wherein the torque or current flowing through the electric motor (EM) is adjusted by adjusting command signals (ICS) controlling an inverter (IVT) feeding the electric motor.

9. A system for controlling a device comprising an electric motor (EM) for assisting a turbo (TTB) or a compressor (TCP), the system comprising processing circuitry (ECU) configured to implement the method of any one of claims 1 to 8.

10. A vehicle comprising a turbo (TTB) or a compressor (TCP), an electric motor (EM) for assisting a turbo or compressor and a system (ECU) according to claim 9.

11. The vehicle according to claim 10, further comprising an internal combustion engine (10).

12. The vehicle according to claim 10, further comprising a fuel cell.

13. A computer program product comprising program code for performing, when executed by a processing circuitry (ECU), the method of any one of claims 1 to 8.

14. A non-transitory computer-readable storage medium comprising instructions, which when executed by a processing circuitry (ECU), cause the processing circuitry to perform the method of any one of claims 1 to 8.

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