Control strategy for an electric machine in a vehicle

Abstract

Vehicle (10) comprising the following: a traction battery (14); at least one electric machine (16); a variable voltage converter (60) which is configured to vary a voltage between the traction battery (14) and the electric machine (16), wherein an output side of the variable voltage converter (60) is coupled to a high-voltage bus (36), and wherein the variable voltage converter (60) is set up to increase the voltage of the traction battery (14) for the high-voltage bus (36), a control device (12) that is configured to: to change the voltage between the traction battery (14) and the electric machine (16) based on a measured high-voltage bus signal of the high-voltage bus (36) of the traction battery (14); and In response to a notification that the measured high-voltage bus signal is faulty, the voltage between the traction battery (14) and the electric machine (16) is changed based on a substitute battery voltage signal so that the electric machine (16) remains operational for one driving cycle.

Description

AREA OF TECHNOLOGY

[0001] The present disclosure relates to a system for controlling an electric machine in an electric vehicle. GENERAL STATE OF THE ART

[0002] Battery electric vehicles (BEVs) contain a traction battery that can be recharged from an external electrical power source and powers the electric motor. Hybrid electric vehicles (HEVs) contain an internal combustion engine, one or more electric motors, and a traction battery that at least partially powers the electric motor. Plug-in hybrid electric vehicles (PHEVs) are similar to HEVs, but the traction battery in a PHEV can be recharged from an external electrical power source. These vehicles are examples of vehicles that can be at least partially powered by an electric motor.

[0003] In these vehicles, if a malfunction is detected in a component necessary for the electric drive, various actions may be required to ensure the safety of the vehicle occupants. Because shutting down the entire vehicle is undesirable, Limited Operation Strategy (LOS) modes can be implemented to allow the operator to continue driving while individual components are shut down.

[0004] WO 2011 / 152 200 A1, US 2009 / 0 315 698 A1, DE 10 2011 108 038 A1, US 2007 / 0 120 530 A1 and US 6 331 365 B1 disclose generic vehicle tax procedures. BRIEF DESCRIPTION OF THE INVENTION

[0005] The objective technical problem to be solved can be seen as eliminating or at least reducing the disadvantages of the prior art. This problem is solved by the subject matter of the independent claim. In one embodiment of the disclosure, a vehicle is provided comprising a traction battery, at least one electric machine, a variable voltage converter configured to vary the voltage between the traction battery and the electric machine, wherein an output side of the variable voltage converter is coupled to a high-voltage bus, and wherein the variable voltage converter is configured to increase the voltage of the traction battery for the high-voltage bus, and a control device.The control unit is configured to change the voltage between the traction battery and the electric machine based on a measured high-voltage bus signal from the traction battery's high-voltage bus. In response to a report that the measured high-voltage bus signal is faulty, the control unit instead changes the voltage between the traction battery and the electric machine based on a substitute battery voltage signal, ensuring the electric machine remains operational for one driving cycle.

[0006] In another embodiment, the measured high-voltage signal is faulty if it exceeds a threshold range.

[0007] In another embodiment, the vehicle also includes at least one sensor for measuring and providing the measured high-voltage bus signal.

[0008] In another embodiment, the backup battery voltage signal is provided by a battery control unit in response to the faulty measured high-voltage bus signal of the traction battery's high-voltage bus.

[0009] In another embodiment, the alternative battery voltage signal is provided by the battery control unit via a vehicle control area network (CAN).

[0010] In one embodiment of the disclosure, a vehicle is provided that includes a traction battery, a high-voltage bus for providing high voltage to at least one electric machine, and a control device. The control device is configured to change the voltage between the battery and the electric machine based on a measured voltage from the high-voltage bus. In response to a signal indicating that the measured voltage is faulty during a driving cycle, the control device instead changes the voltage between the battery and the electric machine based on a substituted battery voltage signal, so that the electric machine remains operational for the duration of the driving cycle.

[0011] In another embodiment, the control device includes a variable voltage converter.

[0012] In another embodiment, the variable voltage converter is set to a mode in response to the faulty measured signal of the high-voltage bus, which prevents the provision of an increased voltage to the at least one electrical machine.

[0013] In another embodiment, the substitute battery voltage signal is the same as a measured battery voltage signal.

[0014] In another embodiment, the measured voltage is faulty if it exceeds a threshold range.

[0015] In another embodiment, the vehicle also includes at least one sensor for providing the measured voltage signal of the high-voltage bus.

[0016] In one embodiment of the disclosure, a method for controlling a hybrid vehicle is provided. The method involves varying the voltage between a traction battery and an electric machine based on a measured voltage signal. In response to an indication that the measured voltage signal is faulty during a driving cycle, the method substitutes it with an alternative voltage signal. The method then varies the voltage between the battery and the electric machine based on the alternative voltage signal so that the electric machine remains operational for the duration of the driving cycle.

[0017] In another embodiment, if the measured voltage signal is based on a battery voltage, the alternative battery voltage signal is replaced by a battery control unit.

[0018] In another embodiment, the alternative battery voltage signal is provided by the battery control unit via a vehicle control area network (CAN).

[0019] In another embodiment, if the measured voltage signal is based on a high-voltage bus voltage, an alternative high-voltage signal replaces the erroneous measured voltage signal and is set to the same value as a battery voltage signal. A variable voltage converter is set to a mode that prevents the provision of an increased voltage to at least one of the electrical machines. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic diagram of a hybrid electric vehicle according to an embodiment of the disclosure; Fig. Figure 2 is a block diagram that shows an example of a vehicle's control system. Fig. 1 illustrates; Fig. Figure 3 is a schematic illustration of a part of the vehicle. Fig. 1; Fig. Figure 4 is a schematic illustration of a variable voltage converter (VVC) from Fig. 3; Fig. 5 is a flowchart of an algorithm that is used in a vehicle's control system. Fig. 1 is implemented according to an embodiment of the disclosure; Fig. Figure 6 is a flowchart of another algorithm used in the vehicle's control system. Fig. 1 is implemented according to an embodiment of the disclosure; and Fig. 7 is a flowchart of another algorithm used in the vehicle's control system. Fig. 1 is implemented according to an embodiment of the disclosure; Fig. Figure 8 is a flowchart of another algorithm used in the vehicle's control system. Fig. 1 is implemented according to an embodiment of the disclosure; Fig. Figure 9 is a flowchart of another algorithm used in the vehicle's control system. Fig. 1 is implemented according to an embodiment of the disclosure; and Fig. Figure 10 is a flowchart of another algorithm used in the vehicle's control system. Fig. 1 is implemented according to an embodiment of the disclosure. DETAILED DESCRIPTION

[0020] The figures are not necessarily to scale; some features may be exaggerated or reduced in size to show details of specific components. Therefore, specific structural and functional details disclosed herein should not be interpreted as limiting, but merely as a representative basis to teach those skilled in the art how the present invention can be used in different ways.

[0021] With reference to Fig. Figure 1 illustrates a hybrid electric vehicle 10 with a power-split powertrain. A vehicle control system 12 is provided and can generally be referred to as a control unit. The vehicle control system 12 controls the power distribution in the powertrain or drive system of the vehicle 10.

[0022] Vehicle 10 contains a traction battery 14. The battery 14 has an electrical switching circuit, so that the battery 14 receives and stores electrical energy, for example, through regenerative braking. The battery 14 also supplies energy to an electric machine, such as an electric traction motor 16.

[0023] Although the vehicle's control system 12 10 in Fig. While Figure 1 illustrates a single control unit, such a control system can, if desired, contain more than one control unit. For example, a separate battery control module can directly control the battery 14. Furthermore, a separate engine control module can be directly connected to the engine 16 and to the other control units in the vehicle 10. It should be understood that all provided control units in the vehicle 10 can be referred to as a "control unit" and that the vehicle control system 12 is not necessarily limited to only one control unit. Separate additional control units and their hierarchy are described in Figure 1. Fig. 2 described in more detail.

[0024] An inverter 15 is provided to convert direct current from the battery into alternating current to power the electric machine. The inverter 15 may also selectively enable / disable the electrical flow from the battery 14 to the motor 16. Alternatively, during regenerative braking, the inverter 15 converts alternating current from the electric machine into direct current, thus storing electrical power in the battery 14.

[0025] An internal combustion engine 18 also serves as a power source for the vehicle 10. The vehicle control system 12 controls the operation of the engine 18. Both the motor 16 and the engine 18 are capable of driving a transmission 20, which ultimately delivers the torque to the wheels of the vehicle 10.

[0026] The power unit 18 delivers power to a torque input shaft 22, which is connected via a freewheel clutch to a planetary gear set 24. The input shaft 22 drives the planetary gear set 24. The planetary gear set 24 includes a ring gear 26, a sun gear 28, and a planet carrier assembly 30. The input shaft 22 can be driven by the carrier assembly 30, which, when energized, can rotate the ring gear 26 and / or the sun gear 28. The sun gear 28 can be driven by a generator 32. The generator 32 may be engaged with the sun gear 28, so that the generator 32 may rotate with the sun gear 28, or it may be disengaged, so that the generator 32 does not rotate with the sun gear 28.Like the motor 16, the generator 32 can be described as an electric machine which, when used in other vehicle powertrain configurations, is capable of both generating electrical power and providing kinetic energy.

[0027] When the power unit 18 is coupled to the planetary gear set 24, the generator 32 generates energy as a reaction to the operation of the planetary gear set 24. Electrical energy generated by the generator 32 is transferred to the battery 14 via electrical connections 36. The battery 14 receives and stores electrical energy in a known manner, including through regenerative braking. The battery 14 supplies the stored electrical energy to the motor 16 for operation. The portion of the power supplied by the power unit 18 to the generator 32 can also be transferred directly to the motor 16. The battery 14, the motor 16, and the generator 32 are each interconnected via a bidirectional electrical flow path through electrical connections 36. The vehicle control system 12 controls the components in the drivetrain to provide an appropriate torque distribution to the wheels.

[0028] It should be understood that the motor 16 and the generator 32 can each be referred to as an electric machine. Each electric machine can operate as a generator by receiving torque from the power machine 18 and supplying alternating current to the inverter 15, which then converts the voltage into direct current to charge the battery 14. Each electric machine can also operate as a generator by converting the vehicle's braking energy into electrical energy using regenerative braking, which is stored in the battery 14. Alternatively, each electric machine can operate as a motor, receiving power from the inverter 15 and the battery 14 and providing torque through the transmission 20 and ultimately to the wheels 58.

[0029] The inverter 15 selectively drives the motor 16 and the generator 32. The inverter 15 can include a motor inverter for selectively switching off the motor 16 and a generator inverter for selectively switching off the generator 32.

[0030] The vehicle 10 also includes a variable voltage converter (VVC) 60, also known as a boost converter, for varying the voltage between the battery 14 and the motor 16 and generator 32. The VVC 60 is used to increase the voltage of the battery 14 to a higher voltage. The higher voltage in a hybrid-electric powertrain system can be used for a variety of purposes, such as optimizing the torque capability of electric machines, optimizing network losses, and other hybrid-electric system optimizations. The VVC 60 allows the vehicle 10 to use a smaller battery pack with a lower voltage while maintaining the functionality associated with the higher voltage. A smaller battery pack may offer advantages such as lower cost, smaller size, and fewer installation limitations. The VVC 60 is used in Fig. 3 and Fig. 4 described in more detail.

[0031] The vehicle 10 may be powered solely by the power unit 18, solely by the power unit 18 and the generator 32, solely by the battery 14 and the motor 16, or by a combination of the power unit 18, the battery 14, the motor 16, and the generator 32. In a mechanical drive mode or a first operating mode, the power unit 18 is activated to deliver torque through the planetary gear set 24. The ring gear 26 distributes the torque to stepped gear transmission elements 38, which comprise meshing gear elements 40, 42, 44, and 46. The transmission elements 42, 44, and 46 are mounted on a countershaft, and transmission element 46 distributes the torque to transmission element 48. Transmission element 48 then distributes the torque to a torque output shaft 50. In mechanical drive mode, the motor 16 may also be activated to assist the power unit 18 in driving the transmission 20.When the motor 16 is active during support, the transmission element 52 distributes the torque to the transmission element 44 and to the countershaft.

[0032] In an electric drive mode (EV mode) or a second operating mode, the power unit 18 is switched off or otherwise prevented from distributing torque to the torque output shaft 50. In EV mode, the battery 14 drives the motor 16 to distribute torque through the step-through transmission elements 38 and to the torque output shaft 50. The torque output shaft 50 is connected to a differential axle mechanism 56, which distributes torque to the drive wheels 58. The vehicle control system 12 controls the battery 14, the motor 16, the power unit 18, and the generator 32, respectively, to distribute torque to the wheels 58 in either the mechanical drive mode or the EV mode, according to the driver's torque requirements.

[0033] As previously described, there are two power sources for the drive system. The first power source is the power machine 18, which supplies torque to the planetary gear 24. The other power source involves only the electric drive system, which includes the motor 16, the generator 32, and the battery 14, with the battery 14 serving as an energy storage medium for the generator 32 and the motor 16. The generator 32 may be driven by the planetary gear 24 and may alternatively serve as a motor, supplying power to the planetary gear 24.

[0034] It should be understood that, although a power-split powertrain is illustrated in vehicle 10, vehicle 10 can contain many other configurations. Accordingly, it is intended that individual components of the powertrain may differ to be suitable for various specific applications. For example, in another configuration that does not include planetary gear 24, an electric machine (motor / generator) may be provided for operation as a generator by receiving torque from the power machine or as a result of regenerative braking, while the same electric machine may also be operated as a motor by receiving power from the traction battery and providing torque through the transmission.Other vehicle configurations of vehicle powertrains and implementations of electrical machines are also provided for and are therefore considered to be within the scope of protection of the present disclosure.

[0035] With reference to Fig. Figure 2 shows a block diagram illustrating a vehicle control system 12 within the vehicle 10. A driver inputs a request 62, for example, pressing the accelerator pedal to initiate an acceleration request, or pressing the brake pedal to initiate a braking request. The driver inputs 62 are received by a vehicle system controller (VSC) 64. The VSC 64 processes these driver inputs 62 and communicates commands throughout the vehicle 10.

[0036] The vehicle control system 12 can be electrically connected to various subsystems in the vehicle 10 and serves as the overall control unit of the vehicle 10. The VSC can be electrically connected to and communicate with various subsystems via a vehicle network 65. The vehicle network 65 continuously transmits data and information in a broadcast to the vehicle-based systems. The vehicle network 65 may be a controlled area network (CAN) bus used to transmit data to and from the VSC 64, as well as to and from other various control units, subsystems, or components thereof. For example, as in Fig. As shown in Figure 2, the VSC 64 can be connected via the vehicle network 65 to a hybrid control unit (HCU) 66, a battery control module (BCM) 72 and an engine control unit (ECU) 68.

[0037] The HCU 66 controls the hybrid-specific components in the vehicle 10, such as the motor 16, the generator 32, the battery 14, and / or the inverter 15. The HCU 66 is communicatively linked to the ECU 68, enabling the HCU 66 to command the ECU 68 to control the power unit 18 in various ways. A battery control module (BCM) 72 may also communicate with the HCU 66. The BCM 72 may receive commands from the HCU 66 and control the power distribution of the battery 14.

[0038] The HCU 66 is also communicatively connected to a Motor / Generator Control Unit (MGCU) 70. The MGCU 70 communicates with the HCU 66 via a Serial Peripheral Interface (SPI) 71. The SPI 71 is a four-wire serial bus. The SPI 71 is a very simple hardware interface and is not limited to a maximum clock frequency, thus enabling potentially high throughput. The MGCU 70 receives commands from the HCU 66 and controls the motor 16, the generator 32, and the VVC 60. As shown in Fig. As further illustrated in Figure 2, the MGCU 70 is communicatively connected to inverter control units 74. The motor / generator inverter control units 74 receive commands from the MGCU 70 and open and close switches within the inverter 15 to enable and block current flow to and from the electrical machines.

[0039] Earlier hybrid electric vehicles used a single control module to manage the motor, generator, and VVC. Within the control module, a single microcontroller controlled the motor, another controlled the generator, and a third controlled the VVC. However, it was found that controlling the VVC was difficult when it was separate from the motor / generator, and that it was too slow in transmitting information from the motor or generator to the VVC controls in the HCU. Therefore, it is advantageous to control the VVC, motor, generator, and their respective inverters from a single control unit, such as the one described in Fig. 2 MGCUs shown.

[0040] A hierarchy of control devices is thus established in the Fig. Figure 2 is provided. Other hierarchies of control units are also provided without deviating from the scope of protection of this disclosure. For example, the VSC 64 may communicate directly with the MGCU 70 without the need for an HCU 66. Other configurations are also provided that would be advantageous for different specific vehicle architectures.

[0041] The vehicle control system 12 controls each of the control units according to requested torque and power demands. It should also be understood that more or fewer control units than those described herein are provided, and that one or more of these control units may communicate with each other to perform certain tasks. Any or all of these control units, or a combination thereof, may simply be referred to as a "control unit".

[0042] With current reference to Fig. 3 and Fig. Section 4 describes in more detail a schematic diagram of a part of a hybrid electric vehicle 10 and a vehicle control system 12. As discussed previously, the VVC 60 is communicatively connected to and controlled by the MGCU. Furthermore, the VVC 60 is connected to the motor / generator inverter control elements 74. In particular, the VVC 60 is used to increase the voltage of the battery 14 in an HEV powertrain system to a higher voltage for various purposes, including, but not limited to, torque capability optimization for electric machines and network loss optimization.

[0043] Battery 14 is connected to the VVC 60 along an input side 76. Battery 14 supplies a low voltage to the VVC 60. The VVC 60 then boosts the low voltage from battery 14 to a higher voltage and outputs the higher voltage to an output side 78. The output side 78 of the VVC 60 supplies the high voltage to the high-voltage bus 36 for use by the inverter 15 and subsequently the motor 16 and the generator 32. As shown in Fig. As shown in Figure 3, the motor 16 and the generator 32 can each have a separate inverter 15. While the VVC 60 is described as having an input side and an output side, it should be noted that in a motor operating mode, the path runs from the battery through the VVC to the high-voltage bus. Conversely, in a regeneration mode, the path runs in the opposite direction.

[0044] Between battery 14 and the VVC 60, a sensor 80 is located to measure the voltage signal along the input side 76 of the VVC 60. Specifically, sensor 80 provides a voltage signal indicating the voltage from battery 14. Along the output side 78, between the VVC 60 and the inverters 15, a second sensor 82 is located. Sensor 82 provides a signal indicating the voltage from the high-voltage bus 36. Sensors 80 and 82 provide a signal indicating the measured voltage along the input side 76 and output side 78, respectively. During normal operating conditions, the measured voltage signal from sensors 80 and 82 is within a specified range. However, if the measured voltage signal from the sensors deviates from this specified range, it may indicate that a fault has occurred and that one of sensors 80 or 82 is malfunctioning.

[0045] With reference to Fig. Figure 4 illustrates a schematic diagram of the VVC 60 circuit. The VVC 60 generally consists of an inductor 84, two mains switches 86 and 88, and associated gate control circuits 90, as shown in Fig. Figure 4 shows that the two mains switches 86, 88 are composed of a bipolar transistor with an insulated gate electrode 92, 94 and an antiparallel diode 96, 98. As shown in Fig. As shown in Figure 4, the switches are arranged as an upper switch 86 and a lower switch 88.

[0046] The VVC circuit arrangement allows for bidirectional current flow depending on vehicle requirements, such as engine operation or regeneration. For example, if the upper switch 86 is closed and the lower switch 88 is open, current flows in one direction through the antiparallel diode 96. Similarly, if the upper switch 86 is open and the lower switch 88 is closed, current flows in one direction through the antiparallel diode 98. However, if both the upper switch 86 and the lower switch 88 are closed, the current flow is bidirectional and generates a voltage increase. This increased voltage is output to the inverter 15, which controls the motor 16 and the generator 32.As previously discussed, the VVC 60 enables the vehicle to have a smaller battery pack by allowing a voltage increase, which, for example, saves costs and requires less battery installation space.

[0047] Certain fault conditions can be detected by one or more of the control units, which may indicate a fault in one of the powertrain components, such as the motor 16, the generator 32, the VVC 60, or the inverter 15. If a fault is detected in one of the components, a Limited Operation Strategy (LOS) can be implemented to allow the vehicle operator to continue driving while certain individual components are shut down. This prevents a complete shutdown of the vehicle 10, which may be undesirable for drivers. The fault conditions that may cause the vehicle 10 and / or the vehicle control system 12 to enter a LOS mode may include the temperature, current, and / or voltage of a powertrain component exceeding an acceptable threshold.A fault condition may be caused by a short-term event and may only be temporary; however, reading a value above a threshold may cause the vehicle control system 12 to issue a command to individually shut down this component, while a command to enter LOS mode allows the operator of the vehicle 10 to continue driving.

[0048] With current reference to Fig. Figure 5 illustrates an exemplary embodiment of the LOS mode at 100, which is not part of the invention. A diagnostic check is performed on each of the motor 16, generator 32, VVC 60, and inverter 15 associated with each of the electrical machines. The diagnostic check determines whether the LOS mode is necessary, thus requiring a temporary shutdown of that component. The MGCU 70 begins performing the diagnostic check, as shown in block 102. Next, as shown in block 104, it determines whether a fault condition exists in the motor and / or motor inverter. If such a fault condition exists, a LOS counter is incremented, as shown in block 106. The LOS counter can be a single-decade counter or an identification device.Once the LOS counter has been incremented by one, as represented by block 108, a motor temporary shutdown flag is set to TRUE. A request is made for the motor to be shut down, as represented by block 110. The motor may be shut down by opening switches in the motor inverter or by opening another switch associated with the motor.

[0049] If there is no fault condition in the motor and / or motor inverter, it is determined whether the LOS counter is greater than zero, as shown by block 112. If the LOS counter is not greater than zero, the motor temporary shutdown flag is set to FALSE, and a request is made for the motor to be switched on or remain switched on, as shown by block 116.

[0050] However, if the LOS fault counter is greater than zero, the LOS counter is decremented, or reduced, as shown by block 118. After the LOS counter has been reduced, it is determined whether the fault counter has reached zero, as shown by block 120. If the LOS counter is zero, the procedure continues by setting the engine shutdown flag to FALSE, as shown by block 114, and requesting that the engine be started or remain running, as shown by block 116. If the fault counter remains greater than zero, the procedure continues again to shut down the engine, as shown by blocks 108 and 110. Finally, the TRUE and FALSE flags are sent to the vehicle control system, as shown by block 122. The vehicle can then be controlled based on the information sent to the vehicle control system, according to the instructions provided in the following section: Fig. Act as described in section 6.

[0051] By requiring the fault counter to be zero, as represented by block 120, the control system ensures that even if no fault condition is determined in the motor and / or motor inverter, the motor remains temporarily shut down for a period of time if the LOS fault counter is still above zero. This allows the diagnostics to be performed multiple times, with the LOS fault counter being decremented each time until it reaches zero. This results in multiple tests of the motor and / or motor inverter while the motor is shut down, before the motor is restarted if no fault condition is detected.

[0052] The diagnostic procedure performed by the MGCU causes a temporary engine shutdown if a fault condition is detected. While the engine is temporarily shut down, the vehicle operates in a temporarily reduced-power mode. However, if the fault condition only lasts a short time (e.g., less than 1 second), the LOS mode is interrupted and the engine is quickly restarted, thus reducing any disturbances perceived by the vehicle operator. It should be understood that the entire diagnostic procedure can be completed in less than one second, approximately twenty microseconds, and therefore the period during which the engine is temporarily shut down may not be noticeable to the vehicle operator.

[0053] As in Fig. As shown in Figure 5, LOS mode 100 and the execution of the diagnostic procedure, as depicted by block 102, are performed for the generator, the VVC, and the motor. The diagnostics are generally performed simultaneously for the motor, the generator, the associated inverter, and the VVC, ensuring continuous monitoring for fault conditions in each component. The MGCU can thus temporarily shut down the motor and / or the generator and / or the VVC. It is intended that the diagnostics can also be performed for other components, such as the power unit.

[0054] Fig. Figure 6 illustrates a flowchart 200 of another embodiment of the LOS mode, shown here only as an example and not part of the invention, which is implemented by a control unit or the vehicle control system. As described above, the MGCU sets a flag for either TRUE or FALSE to temporarily switch the engine off or on, as shown by blocks 108 and 114, respectively. The TRUE and / or FALSE flags are received by the MGCU from the vehicle control system, as shown by block 202. If the flag is FALSE, the vehicle control system instructs the MGCU to send back the diagnostic check 102, as shown by block 204.

[0055] However, if the flag is TRUE, it is determined whether the engine was temporarily switched off for at least one threshold period, as shown by block 206. If the engine was switched off for at least one threshold period, it can be permanently switched off for the current ignition cycle, as shown by block 208. In another exemplary embodiment not according to the invention, the threshold period is approximately one second long, so that if the engine was temporarily switched off for at least one second, it will be permanently switched off during the current ignition cycle. However, any suitable threshold period is acceptable, and the threshold period can vary depending on other factors. An ignition cycle may also be referred to as a driving cycle or duty cycle and lasts from the moment the vehicle is switched on, i.e.,The ignition is switched on until the vehicle is switched off when the ignition is switched off. During a new ignition cycle, the engine or any faulty component, such as the VVC or the inverter, may be restarted, as described in [reference to relevant section]. Fig. 7 is described.

[0056] The ones relating to Fig. 5 and Fig. The algorithms described in section 6 involve a diagnostic check of the engine, generator, VVC, or any other powertrain component. In short, if it is detected that a specific powertrain component is operating in a fault condition, this component is temporarily shut down. While temporarily shut down, diagnostics are continuously performed on this component. If the component's fault condition can be corrected, or if it is a transient fault allowing the component to operate under normal conditions within the threshold period, the component can be switched back on. However, if the component's fault condition cannot be corrected within the threshold period, the component is permanently shut down during the current ignition cycle and can only be switched back on during a new ignition cycle (e.g., switching the vehicle off and on again).

[0057] Fig. Figure 7 illustrates a flowchart 300 of another embodiment of the LOS mode, shown here only as an example and not belonging to the invention, which is implemented by a control unit or the vehicle control system. As shown by block 302, the vehicle is requested to start and is instructed to enter a new ignition cycle. Initially, the electrical machines, including the engine, generator, and VVC, are switched off. A series of pre-start safety checks are performed before the vehicle is started.

[0058] For example, the vehicle control system checks whether the current sensor zeroing is complete, as shown in block 304. Current sensor zeroing must be complete in all electrical machines. The current sensors must show a reading of zero while there is no current to ensure accurate readings when current spikes occur during commissioning. Next, a VVC self-test is performed, as shown in block 306. The VVC self-test ensures that any faults within the VVC are detected and corrected. It also determines whether any torque disturbances exist, as shown in block 308. In other words, the available power and / or torque of the electrical machines must be evaluated to determine whether the electrical machines can meet any torque requirements.

[0059] The operating cycle commands provided to the electric machine are deactivated or reset by the control unit, as shown in block 310. Resetting the operating cycle puts the electric machines into a safe mode, thus protecting the hardware. Only after the fault conditions have been cleared can the operating cycle commands be reactivated, enabling safe control of the electric machine. This is considered a "soft restart," where no new ignition cycle is necessary, as opposed to a "hard restart," where the vehicle must be switched off. Finally, as shown in block 312, any faults present in the hardware are identified before the vehicle is switched on for starting.

[0060] Once the pre-start safety checks have been successfully completed, the vehicle starts and the electric motors can start up, as shown by block 314. The electric motors are also fully switched on, and the vehicle can be driven.

[0061] During the operation of the vehicle, the following will be Fig. 5 and Fig. The diagnostic algorithms described in 6 are executed and are represented as block 316. The electrical machines are continuously checked for faults according to the previously described procedures, so that each of them can be temporarily switched off.

[0062] If a request to shut down the electric machines is determined at block 316, the electric machine is shut down as shown by block 318. To restart the electric machine, the vehicle's control systems must undergo a series of safety checks and processes before the electric machine is restarted at block 314. These safety checks and processes allow the vehicle to continue moving and the electric machines to continue providing propulsion power without undergoing an ignition cycle.

[0063] During one of the safety tests, as represented by block 320, the control device determines whether a temporary shutdown of the electric machine is still required, as previously described in relation to block 110. Fig. 5 described. If no shutdown is requested from the electrical machines, the control unit can determine whether any of the electrical machines are requested to be set to a shutdown or continuous shutdown mode, as shown by block 322. If the electrical machines are not shut down, a torque fulfillment test is performed, as shown by block 324. The torque fulfillment test is similar to the test performed with reference to block 308.

[0064] Next, a power limitation and balancing test is performed, as illustrated by Block 326. In this test, the control unit may determine whether a process is currently running that limits electrical power to one of the electrical machines, or that the power or torque limit of one of the electrical machines is not much greater than that of the other electrical machine. The power limitation mode is specified in Fig. 8 is described in more detail. Finally, an overcurrent test is performed, as illustrated by Block 328. The overcurrent test determines whether any electrical machine is assigned a current value above a predetermined threshold or whether any electrical machine is outputting a current value above a predetermined threshold. If all safety tests are satisfactory, the pre-start / restart tests are completed, and the process restarts at Block 302 until the switched-off electrical machine is switched on again at Block 314.

[0065] Fig. Figure 8 illustrates a flowchart 400 of another embodiment of the LOS mode, which is shown here only as an example and is not part of the invention, and which is implemented by a control unit or the vehicle control system. Fig. Section 8 describes a LOS mode, in which a power limiting mode is implemented when a fault condition is detected in one of the electric machines. In previous hybrid-electric vehicles, disturbances or fault conditions in a hybrid-electric vehicle powertrain were difficult to reduce without affecting vehicle performance while the vehicle was being driven or completely stopped, and then required an ignition cycle to partially resume operation. An ignition cycle was necessary to adequately maintain power balance with respect to the faulty unit. In a hybrid-electric transmission, if a fault were detected in one of the units, such as an electric machine, performing an action on only the faulty unit would result in a power imbalance, leading to erratic performance and additional control-related errors.

[0066] To avoid performance imbalances and inconsistent performance, the flowchart 400 describes Fig. 8. The process by which the vehicle enters LOS mode when one of the electric machines malfunctions while driving, and the hybrid-electric powertrain continues to operate with the second electric machine without requiring an ignition cycle. The process described in flowchart 400 allows the control system to quickly compensate for a fault in one of the electric machines and enables the other electric machine to continue providing propulsion power to the vehicle.

[0067] Initially, as depicted by block 402, the control system detects a fault in a first hybrid-electric powertrain component and shuts down the component in response to the fault condition. The fault may occur in one of the electric machines or the associated inverters. In response to the fault condition and the shut-down component, the control system initiates a power limitation mode, as depicted by block 404. Initially, the power limitation mode is executed at a high speed. This high speed could, for example, be an execution speed of 100 microseconds.

[0068] While the control system is still operating at high speed, it temporarily shuts down the second device, as shown by block 406. The VVC is also temporarily set to a diversion mode, as shown by block 408. The VVC's diversion mode allows the high voltage from the electric machines to be quickly diverted to the low-voltage input side of the VVC. A fault may also be displayed to the driver in response to the disturbance, as shown by block 410.

[0069] Once the VVC is in diversion mode and the second device is temporarily disabled, the control system can initiate a power limitation mode, as shown by block 412. The power limitation mode allows the control system to operate at a slower execution speed. This slower execution speed allows the control system to perform a more comprehensive diagnostic evaluation of the system.

[0070] The control system may trigger the power limiting mode after a threshold period to dissipate the high voltage and prevent equipment from being endangered by overvoltage, which could cause further malfunctions. The threshold period may be as short as 20 milliseconds or any suitable period long enough for the high voltage to dissipate. The control system will then operate at a slower speed to allow for additional diagnostics.

[0071] Once the slow power limitation mode is triggered, the control system reactivates the second, non-faulty unit. However, the second unit is reactivated in a torque limitation mode, as shown by block 414. In torque limitation mode, the torque at the functioning unit is limited based on vehicle operation. The maximum torque in LOS mode is limited based on the following formula: τ max=(l max × V battery) / ω

[0072] In other words, the maximum torque in LOS mode is limited based on the maximum permissible current of the high-voltage bus in LOS mode multiplied by the battery voltage and divided by the speed of the second device. In another exemplary embodiment not according to the invention, the maximum permissible current in LOS mode has a fixed value, approximately 150 A. The battery voltage can vary.

[0073] Once the functioning unit is powered on again in a functioning mode, a control system check is performed to determine whether the first unit is still faulty or shut down, as shown in block 416. If the MGCU or HCU requests that the first unit be shut down, or if the first unit continues to be faulty, a power limit timer is incremented, as shown in block 420. However, if there is no fault and no shutdown request from either control unit, the control system may exit power limit mode, as shown in block 424. Exiting power limit mode also terminates the slow execution rate.

[0074] The control system resets the power limit timer to zero, as shown in block 426. Once the power limit timer is reset to zero and the LOS mode is reset, the control system can also re-enable the first and second devices, as shown in block 428. Re-enabled devices include exiting any torque limiting mode and returning to normal operation.

[0075] However, if the first unit is still in a faulty state, or if the MGCU or HCU requests that the unit be shut down or placed in LOS mode, the control system determines whether the power limit timer is greater than a threshold, as represented by block 432.

[0076] If the power limitation timer exceeds a threshold, the slow diagnostic mode is terminated, as shown by block 434. Then, the torque limitation mode is permanently maintained for the functioning device, as shown by block 436. Maintaining the torque limitation mode permanently disables the device. In some exemplary, non-inventive embodiments, the device may only be permanently disabled until a new ignition cycle of the vehicle. The device may be set to be permanently disabled for various reasons, including those described in the Fig. Procedure described in 5-7.

[0077] Fig. Figure 9 illustrates a flowchart 500 of another embodiment of the LOS mode, shown here only as an example and not belonging to the invention, which is implemented by a control unit or the vehicle control system. A high-voltage battery signal, also known as an HVBATT signal, is received by the control unit, for example the MGCU, as shown by block 502. The high-voltage battery signal is measured by the sensor along the input side of the VVC. Based on the high-voltage battery signal provided by the sensor, the control unit determines whether the high-voltage battery signal is valid, as shown by block 504. The high-voltage battery signal is valid if the signal is within an acceptable range.

[0078] If the HVBATT signal is valid, the control unit then continues to use the high-voltage battery signal, as represented by block 506, and the VVC can function normally, for example, when the VVC provides a voltage boost output for the inverters and electrical machines, as shown in Fig. 3 and Fig. 4 described.

[0079] However, if the high-voltage battery signal is outside the acceptable range, the signal is deemed invalid. When the high-voltage battery signal is invalid, the signal is placed in a fault state, as shown by block 508. When the high-voltage battery signal is in the fault state, the MGCU communicates with the HCU to determine if an alternative signal is available to provide the high-voltage battery signal in order to prevent a shutdown or short circuit of the electrical machinery and the vehicle.

[0080] As previously described, the HCU can communicate through the vehicle network like a CAN bus. For example, the HCU can communicate with the BCM in the vehicle network to receive an alternative battery voltage signal from the BCM. This alternative battery voltage signal from the BCM might be a measured voltage taken within the BCM itself. Alternatively, the alternative battery voltage signal could be derived from other battery readings in the BCM or from other vehicle system control units communicating with the vehicle network.

[0081] The MGCU determines whether the alternative voltage signal provided by the vehicle network is valid, as shown in block 510. The alternative battery voltage signal is considered valid if the battery voltage is within an acceptable range. If the BCM considers the alternative battery voltage signal valid, it replaces the HVBATT signal, as shown in block 512. By using the alternative voltage signal instead of the HVBATT signal, the VVC can continue to operate normally, as shown in block 514. In normal operation, the VVC can provide a voltage boost from the battery voltage at the input side to the inverter and electrical machines at the output side.Due to the rapid replacement by the alternative signals, the electric machines can therefore continue to operate normally despite the faulty high-voltage battery signal.

[0082] The vehicle may also display a fault to the driver, as represented by block 516. The fault may be indicated by an oil level warning light, informing the driver of the fault condition. The fault condition in the high-voltage battery signal may be caused by a sensor malfunction. The display may indicate that the sensor needs to be replaced.

[0083] If the MGCU determines that the alternative signal is invalid, the control system ignores it, as shown in block 518. The alternative signal may be invalid if, for example, it is outside an acceptable range or threshold. If the alternative signal is invalid, it may indicate a secondary error.

[0084] Fig. Figure 10 illustrates a flowchart 600 of an embodiment of the LOS mode according to the invention, which is implemented by a control unit or the vehicle control system. A high-voltage bus signal, also known as an HVDC signal, is received by the control unit, for example the MGCU, as shown by block 602. The high-voltage bus signal is measured by the sensor along the output side of the VVC. Based on the high-voltage bus signal provided by the sensor, the control unit determines whether the high-voltage bus signal is valid, as shown by block 604. The high-voltage bus signal is valid if the signal is within an acceptable range.

[0085] If the HVDC signal is valid, the control unit then continues to use the high-voltage bus signal, as shown by block 606, and the VVC can function normally, for example, when the VVC provides a voltage boost output for the inverters and the electrical machines, as shown in Fig. 3 and Fig. 4 described.

[0086] However, if the high-voltage bus signal is outside the acceptable range, the signal is deemed invalid. If the high-voltage bus signal is invalid, the signal is set to an error state, as shown by block 608. If the signal is considered invalid, the HVDC signal is set to an error state, and LOS mode is implemented to maintain the operation of the electrical machines and allow the vehicle operator to continue driving.

[0087] When the high-voltage bus signal is in a fault state, the MGCU attempts to replace the high-voltage battery signal with the high-voltage battery signal, HVBATT, from the VVC input side. The MGCU determines whether the high-voltage battery signal is valid, as shown in block 610. The control unit is designed to be able to replace it with any HVBATT signal, such as the high-voltage battery signal measured by the sensor or the alternative battery voltage signal provided to the MGCU by the CAN bus via the HCU, as shown in Fig. 9 discussed above.

[0088] As previously discussed, the high-voltage battery signal is considered a valid signal if the battery voltage is within an acceptable range. If the high-voltage battery signal is considered valid, the high-voltage bus signal is replaced by the HVBATT signal, as shown in block 612.

[0089] If the high-voltage battery signal is used instead of the high-voltage bus signal, the VVC can continue to operate, but it will be set to a LOS mode, as shown by block 614. In LOS mode, the VVC is set to a diversion mode. In diversion mode, the VVC is prevented from providing a voltage boost, as shown by block 616. The vehicle may also display a fault to the driver, as shown by block 618. Again, the fault may be indicated by an oil level warning light, informing the driver of the fault condition. The fault condition in the high-voltage bus signal may be caused by a sensor malfunction. The indicator may show that the sensor needs to be replaced.

[0090] If the MGCU determines that the HVBATT signal is invalid, the control system ignores the alternative HVBATT signal, as represented by block 620. The alternative signal may be invalid if, for example, it is outside an acceptable range or threshold. If the alternative signal is invalid, it may indicate a secondary error in the HVBATT signal.

[0091] It should be understood that, although references herein apply to the switching on and off of the motor, similar algorithms may be considered that are applicable to the generator, the inverter, and the VVC. In other words, if a fault condition exists in the motor, generator, inverter, or VVC, the procedures described above can also be applied to any of these components and other powertrain components.

[0092] The processes, methods, or algorithms disclosed herein are applicable to / implementable by processing equipment, control equipment, or computer(s), which may contain any existing programmable electronic control units or dedicated electronic control units. Likewise, the processes, methods, or algorithms can be stored as data and instructions executable by a control equipment or computer in many forms, including information permanently stored on non-writable storage media such as ROM devices, and information modifiably stored on writable storage media such as floppy disks, magnetic tapes, CDs, RAM devices, and other magnetic and optical media. The processes, methods, or algorithms can also be implemented in a software-executable object.Alternatively, the processes, procedures or algorithms can be executed in whole or in part using suitable hardware components, such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), sequence control units, control devices or other hardware components or devices, or a combination of hardware, software and firmware components.

[0093] The terms used in the patent specification are descriptive and not limiting terms, and it is understood that various changes can be made without deviating from the idea and scope of protection of the disclosure. Key to symbols

[0094] Fig. 3 V dc V Gleichstrom 15 motor inverters Fig. 7 302 Vehicle start request / Electric machines switched off 304 Current sensor zero adjustment complete? Yes No 306 VVC self-test completed? 308 Torque capable of meeting requirements? 310 Operating cycle reset? 328 Overcurrent? 312 Possible hardware error? 326 Is performance limitation / compensation currently taking place? 314 Vehicle start / Electric machines switched on 324 torque capable of meeting requirements? 318 Switching off electrical machines 316 Shutdown request for electric machine? 322 Power-off mode? 320°C shutdown of electric machine? Fig. 8 402 Control unit detects fault and shuts down 1st unit 404 High-speed power limit LOS mode activation 408 Temporarily setting VVC to redirection mode 406 Temporarily disabling 2nd setup 410 error messages 412 Triggering of power limiting LOS mode at low speed rate 414 Re-enabling VVC and 2nd setup in torque limiting mode 2nd Device 2. Setup 416 Is the first setup still faulty or switched off? No Yes 424 Exiting Power Limiting LOS Mode at Low Speed ​​Rate 420 Incrementing power limit meter 426 Resetting the power limit counter to zero 432 Is power limit time counter > threshold period 428 Re-enabling 1st and 2nd setup 434 Ending from low speed rate 436 Continuously maintaining torque limiting mode in 2nd setup

Claims

[1] Vehicle (10) comprising the following: a traction battery (14); at least one electric machine (16); a variable voltage converter (60) which is configured to vary a voltage between the traction battery (14) and the electric machine (16), wherein an output side of the variable voltage converter (60) is coupled to a high-voltage bus (36), and wherein the variable voltage converter (60) is set up to increase the voltage of the traction battery (14) for the high-voltage bus (36), a control device (12) that is configured to: to change the voltage between the traction battery (14) and the electric machine (16) based on a measured high-voltage bus signal of the high-voltage bus (36) of the traction battery (14); and In response to a notification that the measured high-voltage bus signal is faulty, the voltage between the traction battery (14) and the electric machine (16) is changed based on a substitute battery voltage signal so that the electric machine (16) remains operational for one driving cycle. [2] Vehicle (10) according to claim 1, wherein the measured high-voltage bus signal is faulty if it exceeds a threshold range. [3] Vehicle (10) according to claim 1, further comprising at least one sensor (82) for measuring and providing the high-voltage bus signal. [4] Vehicle (10) according to claim 1, wherein the replacement battery voltage signal is provided by a battery control unit (72) in response to the faulty, measured high-voltage bus signal of the high-voltage bus (36) of the traction battery (14). [5] Vehicle (10) according to claim 4, wherein the backup battery voltage signal is provided by the battery control unit (72) via a vehicle control area network (CAN).

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