Systems for monitoring a power supply

Abstract

System for a vehicle that includes: an inverter coupled with an electric motor and a battery; a controller with computer-readable instructions stored in a non-volatile memory, which, when executed, enable the controller to activate an active short circuit (ASC) and enter a stable state of the inverter in response to one or more of a vehicle speed, an electric motor speed, and a DC bus voltage; a monitoring device configured to monitor a control activity; and an active hardware short circuit (HASC) configured to become active and enter the inverter's stable state in response to the controller being inactive, and to one or more of the vehicle speed, electric motor speed, and DC bus voltage.

Description

TECHNICAL FIELD

[0001] This description generally refers to the monitoring of a low-voltage supply of a control system. BACKGROUND AND SUMMARY

[0002] Electric vehicles may be equipped with one or more controllers that control the operation of various vehicle components. If an electrical connection is altered, the performance of one or more components may be adversely affected. Some examples of electrical connection monitoring include the installation of monitoring hardware and a backup power supply. In such examples, if an electrical connection is detected to be broken or altered, the power supply to the controller is switched to maintain the controller's operation.

[0003] However, the inventors have identified certain drawbacks of previous solutions. For example, if the traction system operates according to specific operating parameters, the switching of an inverter transistor may be synchronized with the movement of a motor's rotor. If a deterioration is detected in an inverter control loop, the traction system and / or a drive system may operate outside of the specified operating parameters, which may lead to deterioration or suboptimal performance. Therefore, methods and systems for managing situations resulting from a change in the inverter control loop may be desirable.

[0004] In one example, the problems described above may be at least partially addressed by a method for an inverter of a traction system including an electric motor, the method comprising selecting between strategies for activating a steady-state inverter based on an electric motor speed and a DC bus voltage. This may increase the longevity of the inverter and traction system components.

[0005] It should be understood that the above summary is intended to introduce, in simplified form, a selection of concepts that are further explained in the detailed description. It is not intended to identify the most important or essential features of the claimed subject matter, the scope of which is clearly defined by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that address the disadvantages noted above or elsewhere in this disclosure. SHORT DESCRIPTION OF THE CHARACTERS

[0006] The above and other advantages of the present disclosure will be readily apparent to those skilled in the art from the following detailed description when considered in light of the accompanying drawings: Fig.1 is a schematic diagram of an exemplary vehicle powertrain according to an embodiment of the present disclosure; Fig. 2 shows a circuit of a vehicle powertrain controller according to an embodiment of the present disclosure; Fig. Figure 3 shows an example of an active hardware short circuit (Hardware Active Short Circuit, HASC) of the circuit of Fig. 2 according to an embodiment of the present disclosure; Fig. 4 shows a graph illustrating an effect of HASC on engine temperature, according to an embodiment of the present disclosure; Fig. 5A shows a diagram illustrating the selection of a first state and / or a second state depending on the conditions according to an embodiment of the present disclosure; Fig.5B shows a diagram of a circuit board of the inverter according to an embodiment of the present disclosure; Fig. 6 shows a method for determining an impairment and selecting one or more of a first state and a second state according to an embodiment of the present disclosure; and Fig. 7 shows an operating sequence of the inverter. DETAILED DESCRIPTION

[0007] The following description refers to the setting of an inverter's operating state depending on a condition. The inverter can be a vehicle inverter, as in Fig. 1. The circuits of a control and an active short circuit are shown in Fig. 2 and 3 respectively. Fig. Figure 4 shows a graph illustrating an effect of the HASC on the engine temperature. Fig.5A shows a diagram illustrating the selection of a first state and / or a second state depending on the conditions. Fig. Figure 5B shows a diagram illustrating a circuit board of the inverter. Fig. 6 shows a method for determining an impairment and selecting one or more of a first state and a second state. Fig. 7 shows an operating sequence of the inverter.

[0008] The inverter's operating state can be set to one of two stable states depending on the motor speed and DC bus voltage. These two stable states can be achieved via one or more short circuits, one configured as software and the other as hardware.

[0009] In Fig.1, a vehicle 100 is shown including a driveline 101 and a transmission 103. The driveline includes a prime mover 106 and a transmission 108. The prime mover 106 may be, for example, an internal combustion engine or a traction motor (e.g., an electric motor) and is operated to provide rotational power to the transmission 108. The transmission 108 may be any type of transmission, such as a manual transmission, an automatic transmission, or a continuously variable transmission. The transmission 108 receives the rotational power generated by the prime mover 106 as input and outputs the rotational power to the transmission 103 according to a selected gear ratio or setting.

[0010] The prime mover 106 may be powered by energy from an energy storage device 105. In one example, the energy storage device 105 is a battery configured to store electrical energy. An inverter 107 may be disposed between the energy storage device 105 and the prime mover 106 and configured to convert direct current (DC) to alternating current (AC).

[0011] Vehicle 100 may be a commercial vehicle, a light-duty, medium-duty, or heavy-duty vehicle, a passenger vehicle, an off-highway vehicle, or an off-highway vehicle. Additionally or alternatively, vehicle 100 and / or one or more of its components may be used in industrial, locomotive, military, agricultural, and aerospace applications. In one example, vehicle 100 is an electric vehicle.

[0012] In some examples, such as Fig.1, the driveline 103 includes a first axle assembly 102 and a second axle assembly 112. The first axle assembly 102 may be configured to drive a first set of wheels 104, and the second axle assembly 112 may be configured to drive a second set of wheels 114. In one example, the first axle assembly 102 is disposed near a front of the vehicle 100 and thus includes a front axle, and the second axle assembly 112 is disposed near a rear of the vehicle 100 and thus includes a rear axle. The driveline 103 is depicted in an all-wheel drive configuration, although other configurations are possible. The driveline 103 may include, for example, front-wheel drive, rear-wheel drive, or all-wheel drive. Additionally, the driveline 103 may include one or more tandem axle assemblies.Thus, the powertrain 103 may have other configurations without departing from the scope of this disclosure, and the configuration of . Fig. 1 is for illustrative purposes and is not limiting. In addition, the vehicle 100 may include additional wheels that are not connected to the drivetrain 103.

[0013] In some all-wheel drive configurations, such as Fig.1, the powertrain 103 includes a transfer case 110 configured to receive the rotational power output from the transmission 108. A first input shaft 113 is drivingly connected to a first output 111 of the transfer case 110, while a second input shaft 122 is drivingly connected to a second output 121 of the transfer case 110. The first input shaft 113 (e.g., a front input shaft) transfers the rotational power from the transfer case 110 to a first differential 116 of the first axle assembly 102 to drive the first set of wheels 104, while the second input shaft 122 (e.g., a rear input shaft) transfers the rotational power from the transfer case 110 to a second differential 126 of the second axle assembly 112 to drive the second set of wheels 114.For example, the first differential 116 is drivingly coupled to a first set of axle shafts 118 coupled to the first set of wheels 104, and the second differential 126 is drivingly coupled to a second set of axle shafts 128 connected to the second set of wheels 114. It is understood that the first set of axle shafts 118 and the second set of axle shafts 128 may each be disposed within a housing.

[0014] In some examples, the vehicle 100 may additionally or alternatively be a hybrid vehicle that includes both a motor and an electric machine, each configured to power one or more of the first axle assembly 102 and the second axle assembly 112. For example, one or both of the first axle assembly 102 and the second axle assembly 112 may be powered by power from the electric machine in a first operating mode in which the electric machine is not operating to provide power (e.g., a motor-only mode), by power from the electric machine in a second operating mode in which the motor is not operating to provide power (e.g., a pure electric mode), and by power from both the motor and the electric machine in a third operating mode (e.g., an electric-assist mode).In another example, one or both of the first axle assembly 102 and the second axle assembly 112 may be an electric axle assembly configured to be driven by an integrated electric machine.

[0015] The vehicle 100 may further include a control system 14. As illustrated, the control system 14 receives information from a plurality of sensors 16 (various examples of which are described herein) and sends control signals to a plurality of actuators 81 (various examples of which are described herein). The sensors 16 may include, for example, a proximity sensor and / or a multimeter coupled to an anti-theft device disposed at an interface between the prime mover 106 and the transmission housing 108 and / or an axle housing.

[0016] The controller 12 may be configured as a conventional microcomputer with a microprocessor unit, input and output ports, read-only memory, random access memory, diagnostic memory, CAN (Controller Area Network) bus, etc. The controller 12 may be configured as a powertrain control module (PCM). The controller may be switched between sleep and wake modes to increase energy efficiency. The controller may receive input data from the various sensors, process the input data, and trigger the actuators in response to the processed input data based on instructions or code programmed therein corresponding to one or more routines.

[0017] Fig.2 shows a schematic representation of a traction system 200. In one example, the traction system 200 is a non-limiting example of the powertrain 103 of the vehicle 100. The traction system 200 includes hardware configured to sense one or more conditions of a vehicle, such as engine speed and engine temperature, to adjust the operating conditions of an inverter 210 of the traction system. The inverter 210 may include a transistor 212. The transistor 212 may be an insulated gate bipolar transistor (IGBT) or a metal-oxide-semiconductor field-effect transistor (MOSFET). A detailed example of the transistor 212 is shown in Fig.5B. Transistor 212 may include a number of gates 213 equal to the number of inputs. In one example, gates 213 may be referred to herein as switches and / or contactors. For example, a battery switch may refer to a contactor connected to a wire connecting the battery to the associated gate of gates 213 of transistor 212.

[0018] A high-voltage (HV) battery 202 may be directly coupled to transistor 212 via a connection 214. A low-voltage (LV) battery 204 may be connected to transistor 212 via a power supply 208. In one example, power supply 208 is configured to supply transistor 212 with a voltage equal to the voltage of low-voltage battery 204. Power supply 208 may include a backup power supply 206. Backup power supply 206 may be a capacitor configured to operate when power to a controller 220 is interrupted, when controller 220 is degraded, or when controller 220 is inactive. In one example, the voltage of the high voltage battery 202 is greater than the voltage of the low voltage battery 204. The high voltage battery 202 may be 48 V and the low voltage battery 204 may be 12 V.Additionally or alternatively, the high-voltage battery 202 may be 24 V and the low-voltage battery 204 may be 12 V. In other examples, the high-voltage battery 202 may be 12 V and the low-voltage battery 204 may be 5 V.

[0019] The controller 220 may be connected to the transistor 212. In one example, the controller 220 is a non-limiting example of the controller 12 of Fig. 1. Additionally or alternatively, the controller 220 may be a controller that only controls the inverter 210 and is separate from the controller 12 Fig. 1. The controller 220 may receive inputs from a sensor system 222 and a Controller Area Network (CAN) 224. In one example, the sensor system 222 may include the sensors 16 from Fig.1. The sensor system 222 may include torque sensors, temperature sensors, speed sensors, and the like. In one example, the sensor system 222 may include at least one voltage sensor configured to measure a voltage of the power supply 208. In addition, the sensor system 222 may also include a sensor configured to measure a frequency of the phase current. In one example, the frequency of the phase current may be used to determine a speed of an electric motor. The CAN 224 may send a torque request to the controller 220, and the controller 220 may output a current torque value to the CAN 224. A diagnostic operation module 226 may provide inputs regarding the desired operation of the transistor 212, the controller 220, and other components of the inverter 210.In one example, the diagnostic operation module 226 may provide input to the controller 220 to adjust the operating parameters of the transistor 212.

[0020] The controller 220 may include a primary operating unit 227 and a secondary operating unit 228. The primary operating unit 227 may perform one or more functional steps (e.g., providing torque requests, adjusting inverter power to the electric motor or high-voltage battery, etc.). The secondary operating unit 228 may perform one or more diagnostic steps to maintain operating parameters within desired operating thresholds. A memory unit 229 may store instructions and / or specific values ​​for comparison with the input values ​​provided to the controller 220.

[0021] The HV battery supply 206, the LV battery supply 208, the HV battery 202, the primary operating unit 227, and the secondary operating unit 228 can each communicate with the corresponding actuators (e.g., gates) of the transistor 212. The actuators can adjust various operating parameters of the transistor 212 based on the signals provided by the controller 220 and the power supplies, thereby adjusting the power delivered by the transistor 212 to the electric motor 230. In one example, the electric motor 230 is a non-limiting example of the prime mover 106 of Fig. 1. The actuators can be a transistor or a switch.

[0022] Inverter 210 may also include a secondary control loop that determines via hardware whether system operation is outside the desired operating parameters. That is, a secondary monitoring system, operating in parallel or in series with the diagnostic operation module, is included in inverter 210 to further promote the desired operation of transistor 212 and increase its service life.

[0023] The secondary control loop may include a hardware unit 240. The hardware unit 240 may be an active hardware short circuit (HASC). The HASC 240 may receive inputs regarding a bus voltage hysteresis and a current frequency of a power phase output of the inverter. The HASC 240 may communicate with a watchdog 244 of a companion chip 242 that is communicatively coupled to the controller 220. The watchdog 244 of the companion chip 242 may monitor a function of the controller 220, including whether the controller 220 is degraded, receiving power, or the like. The bus voltage hysteresis and the current frequency of the power phase output of the inverter may be compared to the determined values ​​to determine whether an adjusted operating mode is desired to mitigate the degradation of the transistor 212. A logic circuit of the HASC 240 is shown in Fig. 3 shown.

[0024] In an example, the example can be Fig. 2 can be used with a 3-phase and / or a 6-phase motor. The number of monitoring circuits (e.g., HASC) can be independent of the motor phases. Thus, the number of monitoring circuits can be different from or equal to the number of motor phases.

[0025] In one example, the voltage sensor may be omitted and a backup encoder powered by a backup power supply may be used. In some examples, the controller 220 may be additionally or alternatively powered by the HV power supply with an LV flyback converter interposed between them. The vehicle's LV power supply may serve as a backup power supply when the HV power supply is interrupted. In some examples, a duplicate of the controller 220 may be integrated into the inverter 210 and act as a backup controller.The duplicate controller may include active short circuit (ASC) software programmed into its memory so that if the controller 220 is degraded or de-energized and unable to execute instructions in its memory related to its ASC to achieve a stable state of the inverter 210, the backup controller may be powered via the backup controller supply. The backup controller may be arranged in place of the HASC 240 or in combination with it.

[0026] Fig. 3 shows an example 300 of the HASC 240. The HASC 240 may include a logic circuit 310 configured to receive a plurality of inputs via a receiver 320. A transmitter element 330 may transmit one or more commands to a device external to the HASC 240.

[0027] The receiver 320 may receive a first input 322 relating to an operation of a controller (e.g., the controller 220 of Fig. 2). The first input 322 can indicate whether the controller is responding. In one example, the first input 322 can be from the watchdog 244 Fig. 2. The watchdog 244 may monitor a status of the controller 220. In one example, the controller 220 may periodically send a signal to the watchdog 244 indicating that it is operating. Additionally or alternatively, the watchdog 244 may be configured to monitor the operation of the controller 220 and detect when the controller 220 is not operating as intended or is shut down.

[0028] The receiver 320 may receive a second input 324 related to a temperature of the vehicle, the electric motor, the controller, or another device of the traction system 200. Fig.2. The temperature input may be used to activate the HASC based on degradation of one or more devices. For example, if the temperature input is above a certain temperature, operation of a device may no longer be desired and the HASC may be activated. The certain temperature may be based on a temperature at which a device no longer functions as desired and performance degradation is detected. In one example, an electronic stop 340 may signal a transmitter 342 to operate in a third operating state (e.g., third operating state 530 from Fig.5), in response to the engine speed being greater than a threshold speed and the temperature being above the specified temperature. In one example, the third operating condition includes the case where the various conditions prevent stable operation and the electronic stop is activated because the HASC 240 is not allowed to activate due to the current conditions. The third operating condition is described in more detail below.

[0029] The receiver 320 may receive a third input 326 related to a measurement of a high-voltage direct current (DC) bus, referred to herein as Vbus. The HASC 240 may monitor the Vbus to determine if the Vbus hysteresis is greater than a threshold. In one example, the Vbus may be used along with a phase current frequency to determine the steady-state mode to use, with the steady-state mode enabled via either the ASC or the HASC 240. As described above, the ASC is a software circuit of the controller and is separate from the HASC 240.

[0030] Logic circuit 310 may send a first output 332 to the controller. The first output 332 may indicate a diagnostic of the operating state of the controller based on the first input 322.

[0031] In one example, when activated to enter a first operating state or a second operating state, the HASC 240 may send a second output 334. The second output 334 may shut off the high voltage through the traction system. The HASC 240 may then limit the torque output of the electric motor to a torque threshold by applying phase limiting via a third output 338. The third output 338 may be based on an input 336, where the input 336 relates to pulse width modulation of the low voltage. In one example, the phase limiting includes reducing the phasing from 6 to 3 phases.

[0032] In one example, the active short circuit can be enabled by the controller when requested and the controller is not compromised. The HASC 240 is a standalone circuit and is enabled when the CPU is unresponsive, which can be controlled by a monitor / watchdog circuit. The motor speed is incorporated into the logic for enabling the HASC 240 or disabling the active short circuit. The active short circuit is disabled at low speeds because there is a range where torque is generated when the phases are shorted. The operation of the various operating states is described in more detail below.

[0033] Fig.4 shows a diagram 400 illustrating a bus voltage 410. The bus voltage 410 is compared to a first threshold 412 and a second threshold 414. The bus voltage 410 may oscillate between the first threshold 412 and the second threshold 414 when switching between the active HASC and the active freewheeling strategy. The HASC may become active when the bus voltage 410 drops toward the second threshold 414. At the second threshold, the bus voltage may be relatively low and require charging via the freewheeling strategy, which may involve opening all six gates of the transistor (e.g., transistor 212 of Fig. 2). The voltage may be kept below the first threshold 412 to prevent impairment of the backup power supply (e.g., backup power supply 206 from Fig. 2) to mitigate.

[0034] Fig.5A shows a diagram 500 illustrating the operating modes as a function of motor speed and motor temperature. The abscissa represents the motor temperature (Tm), and the ordinate represents the motor speed. The dashed line 502 illustrates a motor speed threshold, above or below which an operating state can be switched. The dashed line 504 illustrates a motor temperature threshold, above or below which the operating state can be switched. In some examples, additionally or alternatively, a DC bus voltage and / or a phase current frequency measured via a phase current frequency sensor may be used to estimate the motor speed and / or motor temperature.

[0035] For example, if the engine speed is below the engine speed threshold, the engine temperature may be used when selecting one of the operating states from Fig. 5 may be ignored and a first operating state 510 may be selected. The first operating state 510 may include a freewheeling operation. The first operating state 510 may be executed via instructions stored in the memory of the controller and may stop the commutation of the power module and allow the regenerative current to flow back to the high-voltage battery (e.g., HV battery 202 from Fig. 2). At engine speeds below the engine speed threshold, the voltage between the wires generated by a back-to-back electromagnetic field (EMF) of the engine may be lower than the battery voltage, which may prevent unintended braking torque from being signaled.

[0036] If the motor speed is greater than the motor speed threshold and the motor temperature is lower than the motor temperature threshold, the second operating state 520 may be selected. The second operating state 520 may include an active short circuit (ASC) executed by instructions stored in the controller's memory. Three power phase outputs may be shorted within the inverter (e.g., inverter 210 from Fig.2), which blocks the feedback of current to the HV battery. When the motor speed is above the motor speed threshold, the line-to-line voltage generated by the motor's opposing electromagnetic field is higher than the battery voltage. The second operating state ASC 520 can allow continuous current flow through the inverter's power output phases, which is only desirable when the motor temperature is below the motor temperature threshold while the motor speed is above the motor speed threshold. When the controller is inactive, the HASC can be used to execute the second operating state.

[0037] If the engine speed is greater than the engine speed threshold and the engine temperature is higher than the engine temperature threshold, the third operating state 530 may be selected. The third operating state 530 may include coasting mode in combination with an enabled physical stop interface. In one example, the third operating state is a shutdown state and is reached at high engine speeds and temperatures above the engine speed and temperature threshold.

[0038] Fig. 5B shows an embodiment 550 of a transistor 560. The transistor 560 can be used similarly to the transistor 212 of Fig.2. Transistor 560 indicates that the three phases are shorted by closing T2, T4, and T6 and opening T1, T3, and T5. During the second and third states, the switches of the three-phase inverter 550 can operate identically. In one example, T2, T4, and T6 are turned on, each of the three phases is shorted, and the HASC is active. The third operating state can differ from the second operating state in that the third operating state includes a stop request. In this way, the regenerative current can be blocked. When the phases are shorted to the bus, no voltage is applied and thus no current is returned to the battery. The phase currents are alternating currents (AC) and circulate between the motor and the power module, but not to the battery. When a freewheeling strategy is executed, any of T1, T2, T3, T4, T5, and T6 can be opened.The gates of transistor 560 corresponding to the HV battery or the LV battery can be referred to as battery switches and can be switched from an open to a closed position or vice versa.

[0039] Fig. 6 shows a method 600 for detecting a degradation of the low-voltage supply of a controller. The method 600 may further include selecting an operating state based on one or more of a DC bus voltage, a motor speed, a motor temperature, and a phase current frequency. The instructions for performing the method 600 may be executed by a controller based on commands stored in a memory of the controller and in conjunction with signals received from sensors of the vehicle system, such as the sensors described above with reference to Fig. 1 and Fig.2. The controller may use actuators of the vehicle system to adjust operation according to the method described below.

[0040] The method 600 begins with step 602, which involves determining the operating parameters. The operating parameters include, among others, the power supply status, the controller status, the open request, the motor speed, the opening of one or more IGBT gates, the closing of one or more IGBT gates, the bus voltage hysteresis, the phase current frequency, and the battery switch position. The bus voltage hysteresis may be measured using a first voltmeter connected to the bus. The phase current frequency may be measured using a frequency-to-voltage converter.

[0041] At 604, method 600 may include determining whether a degradation is present. The degradation may include determining whether a power supply to the controller is missing and / or whether the controller is degraded. If no degradation is present, method 600 may include maintaining the current operating parameters at 606.

[0042] At 608, method 600 may include powering the controller with the low-voltage power supply. Thus, the low-voltage battery may provide charge to the controller.

[0043] Returning to 604, if an impairment is present, such as the absence of the low-voltage supply, method 600 may include determining a motor speed at 610. The motor speed may be estimated based on the phase current frequency. For example, the motor speed may increase as the phase current frequency increases.

[0044] At 612, method 600 may include determining the DC bus voltage. The DC bus voltage may provide an indication of whether the high-voltage supply is available for operation of the controller.

[0045] At 614, method 600 may include determining an engine temperature. The engine temperature may be sensed via a temperature sensor and / or estimated based on one or more parameters, including engine speed, an ambient temperature, and a vehicle speed.

[0046] At 616, method 600 may include determining whether the engine speed is below a threshold engine speed and / or whether the Vbus is below a threshold voltage. The threshold engine speed may refer to a relatively low engine speed. In one example, the threshold voltage may be identical to the second threshold 414 of Fig.4. If the engine speed threshold is less than the engine speed threshold, method 600 may include selecting the first operating state at 618. The first operating state may include the freewheeling discharge described above. In an example of real-world operation, the first operating state may be activated in response to an unsolicited braking request at engine speeds below the engine speed threshold.

[0047] If the engine speed is not below the engine speed threshold, method 600 may include determining whether the engine temperature is below an engine temperature threshold at 620. If the engine temperature is lower than the engine temperature threshold, method 600 may include selecting the second state at 622. As described above, the second state may include enabling the ASC.

[0048] If the engine temperature is not below the engine temperature threshold, method 600 determines at 624 that the engine speed is greater than the engine speed threshold and the engine temperature is greater than the engine temperature threshold.

[0049] At 626, method 600 may include selecting a modified version of the first state with a stop request. In one example, the HASC is enabled.

[0050] In one example, the disclosure provides support for a method for entering a steady state inverter to prevent regenerative power from an electric motor from flowing to a battery. An active hardware short circuit (HASC) may be activated when an active hardware short circuit (ASC) is unavailable because a power supply is unavailable and / or because a controller is inactive (e.g., degraded). The HASC or ASC may be activated in response to a service provider's maintenance request for access to the inverter and / or other components of the traction system. Additionally or alternatively, the HASC or ASC may be activated when the electric motor speed is above a threshold, which may occur, for example, when climbing an incline.Additionally or alternatively, the HASC or the ASC can be activated when a battery switch is opened and the speed of the electric motor is greater than the threshold speed.

[0051] The method may include two stable states achieved via three different operating states. A first operating state may achieve a first stable state via the opening of an insulated gate bipolar transistor (IGBT) (e.g., the six switches of Fig.5B are open) when the engine speed is below a lower threshold speed. The lower threshold speed is less than the threshold speed. This can be activated by the ASC or the HASC if the ASC is unavailable. Thus, the battery switch can be open during the first operating state. A second operating state can generate the second stable state by closing the IGBT switches on the three phases. It can be activated by the HASC if the engine speed is above the threshold speed. The third operating state can establish the second stable state via an electronic stop if the HASC is unavailable. The HASC may be unavailable if it is not powered or if the HASC is degraded. Thus, the battery switch can be closed during the second and third operating states.The Vbus hysteresis and phase current frequency can be used to determine the desired steady state. In one example, the phase current frequency can provide an indication of the electric motor's speed. This allows the ASC to activate the steady state when the controller is operating without faults. The HASC can activate the steady state when the controller is operating with faults or no power is available. The electronic stop can activate the steady state when the HASC cannot be activated. Table 1 - Steady State Strategy Contactor position Engine speed Control functional Control impaired Closed High ASC HASC Closed Low Freewheel Freewheel Open High ASC freewheel HASC freewheel Open Low Freewheel Freewheel

[0052] Table 1 above shows a strategy for achieving a steady state of the inverter, including whether the ASC or the HASC activates the steady state. High and low motor speeds can be compared to a single threshold, e.g., the motor speed threshold indicated by the dashed line 502 in Fig.5A. As shown in Table 1, the ASC provides the steady state when the control is functional, the motor speed is high, and the contactor is closed. When the control is degraded, the motor speed is high, and the contactor is closed, the HASC provides a steady state. When the control is functional or degraded, the motor speed is low, and the contactor is closed, the freewheel (FW) provides the steady state. When the control is functional, the motor speed is high, and the contactor is in an open position, the ASC and freewheel provide the steady state. When the control is degraded, the motor speed is high, and the contactor is in an open position, the HASC and freewheel provide the steady state.

[0053] Fig.7 graphically illustrates an operating sequence 700 illustrating the state of components of a traction system. Trace 710 illustrates an engine speed, dashed line 712 illustrates an upper threshold for the engine speed, and dashed line 714 illustrates a lower threshold for the engine speed. Trace 720 illustrates a Vbus, dashed line 722 illustrates an upper threshold voltage of the HASC, and dashed line 724 illustrates a lower threshold voltage of the freewheel. Trace 730 illustrates control activity. Trace 740 illustrates a battery switch position. Trace 750 illustrates whether the ASC is on or off. Trace 760 illustrates whether the HASC is on or off. Trace 770 illustrates whether the freewheel is on or off.

[0054] Before t1, the motor speed is above the upper motor speed threshold. This allows stable operation of the inverter to be requested. The Vbus is above the upper HASC voltage threshold. The controller is active and the battery switch is closed. Therefore, only the ASC is activated to initiate the inverter's steady state. In one example, the steady state can limit braking by the electric motor and / or the regenerative current.

[0055] At t1, the motor speed drops below the upper motor speed threshold and remains above the lower motor speed threshold. Between t1 and t2, stable inverter operation may not be required, and the inverter can enable braking via the electric motor and / or regenerative current.

[0056] At t2, the engine speed rises above the upper threshold of the engine speed. This calls for stable operation of the inverter. Between t2 and t3, the battery switch is in the open position and the controller is active. Thus, ASC and freewheeling are used to achieve the steady state. In one example, the ASC is operated for a threshold period before the freewheeling strategy is applied (e.g., opening the gates of an inverter circuit, such as the circuit in Fig. 5B) to maintain stable operation.

[0057] At t3, the motor speed drops below the upper motor speed threshold and remains above the lower motor speed threshold. Between t3 and t4, stable inverter operation may not be required, and the inverter can enable braking via the electric motor and / or regenerative current.

[0058] At t4, the engine speed rises above the upper threshold. This requests stable inverter operation while the battery switch is open. The controller is not active. Therefore, the ASC cannot be triggered based on feedback from a monitoring device, such as the watchdog 244 of the companion chip 242. Fig.2, which indicates to the HASC that the controller is not powered and / or degraded. Between t4 and t5, the HASC is activated. Furthermore, because the contactor is open, the freewheel can be triggered alternately with the HASC. For example, the HASC can operate based on the Vbus for a certain threshold period. Once the Vbus reaches the lower threshold freewheel voltage, the HASC can be disabled and the freewheel enabled. The HASC can be re-enabled once the Vbus reaches the HASC's upper threshold voltage. The freewheel and HASC can continue to alternate based on the Vbus voltage during stable operation. In one example, the HASC is powered through a capacitor whose charge equals the Vbus. When the capacitor charge decreases, the HASC is disabled and the freewheel is enabled to recharge the capacitor.

[0059] At t5, the engine speed drops below the upper engine speed threshold. The battery switch is moved to the closed position. Between t5 and t6, the engine speed remains above the lower engine speed threshold. Thus, stable operation of the inverter is not required.

[0060] At t6, the motor speed rises above the upper motor speed threshold. This requires stable inverter operation. Between t6 and t7, the control is inactive. This activates the HASC and the Vbus voltage drops. If the battery switch is closed, no capacitor damage may occur, and protecting the capacitor via the freewheel may not be desirable. Thus, between t6 and t7, only the HASC is activated.

[0061] At t7, the motor speed drops below the lower motor speed threshold. After t7, the motor speed remains between the upper and lower motor speed thresholds. Thus, stable operation of the inverter is not required.

[0062] The disclosure provides support for a method for an inverter of a traction system having an electric motor, the method including selecting between strategies for activating a steady state of the inverter based on an electric motor speed and a DC bus voltage. A first example of the method further includes selecting an active hardware short circuit (HASC) to activate the steady state in response to the electric motor speed being greater than a threshold and the DC bus voltage being less than a threshold voltage, the threshold voltage being based on an electromagnetic field (EMF) voltage of the motor.A second example of the method, optionally including the first example, further includes selecting an active hardware short circuit (HASC) to activate the steady state in response to a battery switch being closed, the speed of the electric motor being greater than a threshold speed, and one or more of the following conditions being met: a controller degradation or a power interruption.A third example of the method, optionally including one or more of the preceding examples, further includes selecting an active hardware short circuit (HASC) and freewheeling to activate the steady state in response to a battery switch being open, the electric motor speed being greater than a threshold speed, and control being degraded, wherein the HASC is activated for a threshold period before initiating a freewheeling function by opening all switches of the inverter. A fourth example of the method, optionally including one or more of the preceding examples, further includes a capacitor providing backup power to the HASC during the threshold period. A fifth example of the method, optionally including one or more of the preceding examples, further includes recharging the capacitor via freewheeling operation after the threshold period.A sixth example of the method, optionally including one or more of the preceding examples, further includes selecting an active short circuit (ASC) and a freewheel to activate the steady state in response to a battery switch being open, the electric motor speed being greater than a threshold speed, and a controller being powered, wherein the ASC is activated for a threshold duration before initiating a freewheel function by opening all switches of the inverter.

[0063] The disclosure additionally provides support for a system for a vehicle including an inverter coupled to an electric motor and a battery, a controller having computer-readable instructions stored in a non-volatile memory thereof that, when executed, enable the controller to activate an active short circuit (ASC) and enter a steady state of the inverter in response to one or more of a vehicle speed, an electric motor speed, or a DC bus voltage, a monitor configured to monitor activity of the controller, and an active hardware short circuit (HASC) configured to become active and enter the steady state of the inverter in response to the controller being inactive and in response to one or more of the vehicle speed,the electric motor speed and the DC bus voltage. A first example of the system further includes the controller being inactive when the controller is degraded or when the power supply is interrupted. A second example of the system, optionally including the first example, further includes the electric motor speed being determined based on a phase current frequency, wherein the phase current frequency is sensed via a sensor. A third example of the system, optionally including one or more of the preceding examples, further includes a voltage sensor sensing the DC bus voltage. A fourth example of the system, optionally including one or more of the preceding examples, further includes the instructions enabling the controller to enter the steady state via a combination of the ASC and a coasting strategy when a battery switch is open,the electric motor speed is greater than a threshold speed and the controller is active, wherein the freewheeling strategy comprises gates of a circuit being open. A fifth example of the system, optionally including one or more of the preceding examples, further includes the HASC being configured to transition the inverter to the steady state when the controller is inactive, the electric motor speed is greater than a threshold speed, and a battery switch is open, wherein the HASC operates in combination with a freewheeling strategy, wherein the freewheeling strategy comprises gates of a circuit being open. A sixth example of the system, optionally including one or more of the preceding examples, further includes the HASC and the freewheeling strategy operating alternately for specific periods of time, wherein a specific period of time is based on the DC bus voltage. A seventh example of the system,optionally including one or more of the preceding examples, further includes that the steady state comprises reducing a torque output of the electric motor.,

[0064] The disclosure further provides support for a method for a traction system of a vehicle including an inverter, an electric motor, and a battery, the method including determining activity of a controller, determining an electric motor speed, determining a DC bus voltage, entering a steady state based on one or more of the electric motor speed and the DC bus voltage, and selecting an active short circuit (ASC) or an active hardware short circuit (HASC) based on the activity of the controller. A first example of the method further includes a power supply of the controller being different than a power supply of the HASC.A second example of the method, optionally including the first example, further includes where entering the steady state comprises using only the ASC, only the HASC, the ASC in combination with a freewheeling strategy, the HASC in combination with the freewheeling strategy, or only the freewheeling strategy. A third example of the method, optionally including one or more of the preceding examples, further includes turning the HASC on and off based on the DC bus voltage during the steady state, wherein a freewheeling strategy is activated when the HASC is off. A fourth example of the method, optionally including one or more of the preceding examples, further includes where the steady state is further based on a position of the battery switch.

[0065] The term “approximately” means plus or minus five percent of the range, unless otherwise stated.

[0066] The following claims particularly point out certain combinations and subcombinations that are considered novel and non-obvious. These claims may refer to "a" element or "a first" element, or the equivalent thereof. Such claims are to be construed as including the inclusion of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amending the present claims or by filing new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope than the original claims, are also considered to be within the subject matter of the present disclosure.

Claims

[1] System for a vehicle comprising: an inverter coupled to an electric motor and a battery; a controller having computer-readable instructions stored in a non-volatile memory thereof that, when executed, enable the controller to enable an active short circuit (ASC) and enter a steady state of the inverter in response to one or more of a vehicle speed, an electric motor speed, and a DC bus voltage; a monitoring device configured to monitor an activity of the controller; and an active hardware short circuit (HASC) configured to become active and enter the inverter steady state in response to the controller being inactive and one or more of the vehicle speed, the electric motor speed, and the DC bus voltage. [2] The system of claim 1, wherein the controller is inactive when the controller is impaired or when a power supply is interrupted. [3] A system according to any preceding claim, wherein the electric motor speed is determined based on a phase current frequency, the phase current frequency being detected by a sensor. [4] A system according to any preceding claim, wherein a voltage sensor detects the DC bus voltage. [5] The system of any preceding claim, wherein the instructions further enable the controller to enter the steady state via a combination of the ASC and a coasting strategy when a battery switch is open, the electric motor speed is greater than a threshold speed, and the controller is active, the coasting strategy comprising gates of a circuit being open. [6] The system of any preceding claim, wherein the HASC is configured to transition the inverter to the steady state when the controller is inactive, the electric motor speed is greater than a threshold speed, and a battery switch is open, the HASC operating in combination with a freewheeling strategy, the freewheeling strategy comprising gates of a circuit being open. [7] The system of claim 6, wherein the HASC and freewheeling strategies operate alternately for specific periods of time, a specific period of time based on the DC bus voltage. [8] A system according to any preceding claim, wherein the steady state comprises reducing a torque output of the electric motor.

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