Method and system for managing key off load

Abstract

The present disclosure provides methods and systems for managing key-off loads. Systems and methods for operating a vehicle power system are described. The vehicle power system includes a lower voltage battery and a power distribution system. Power supplied to the power distribution system may be switched from one source to another based on the estimated electrical load.

Description

Technical Field

[0001] The present disclosure relates to methods and systems for managing power in a vehicle after key-off. The methods and systems may be particularly useful for electric vehicles. Background Art

[0002] A vehicle may include alternating current (AC) and direct current (DC) power outlets that allow a user to access power derived from the vehicle's power supply. While the vehicle is operating, the AC and DC power outlets may be active. The AC and DC power outlets may be powered by the same power source, such as a traction battery. However, the power provided by the power source may be converted by an inverter to generate AC power, which is supplied to the AC power outlet, and the DC power may be provided via a DC / DC converter. Because the traction battery has a limited storage capacity, it may be desirable to manage the power provided by the traction battery. Summary of the Invention

[0003] According to the present invention, a vehicle power system is provided, which has: a first DC / DC converter; a second DC / DC converter, the second DC / DC converter having a higher power output capacity than the first DC / DC converter; and one or more controllers, the one or more controllers including executable instructions for causing the one or more controllers to deactivate or keep deactivating the second DC / DC converter and activate or keep activating the first DC / DC converter after a vehicle key-off event and in response to a first operating condition, and executable instructions for causing the one or more controllers to deactivate or keep deactivating the first DC / DC converter and activate or keep activating the second DC / DC converter after the vehicle key-off event and in response to a second operating condition.

[0004] According to one embodiment, the first operating condition is that the vehicle power consumption value is less than a threshold value.

[0005] According to one embodiment, the second operating condition is that the vehicle power consumption value is greater than the threshold.

[0006] According to one embodiment, the first DC / DC converter and the second DC / DC converter are electrically coupled to a traction battery.

[0007] According to one embodiment, the first DC / DC converter and the second DC / DC converter are electrically coupled to a first voltage bus and a second voltage bus, the first voltage bus being configured to deliver a lower voltage than the second voltage bus.

[0008] According to one embodiment, the invention also features additional executable instructions that cause the one or more controllers to indicate, via a human / machine interface, a likelihood of a decrease in available vehicle range in response to activating or maintaining activation of the second DC / DC converter.

[0009] According to one embodiment, the invention also features additional executable instructions that cause the one or more controllers to monitor power consumption of an inverter prior to the vehicle key-off event and determine the first operating condition or the second operating condition based on the power consumption of the inverter.

[0010] According to the present invention, a method of managing power for a vehicle includes, via one or more controllers, activating or maintaining activation of a first DC / DC converter and deactivating or maintaining deactivation of a second DC / DC converter after deactivating a propulsion system of the vehicle and in response to a first operating condition.

[0011] In one aspect of the invention, the method includes, via the one or more controllers, deactivating or maintaining deactivation of the first DC / DC converter and activating or maintaining activation of the second DC / DC converter after deactivating the propulsion system of the vehicle and in response to a second operating condition.

[0012] In one aspect of the invention, the method includes monitoring an amount of power supplied to an inverter via a DC bus after deactivating the propulsion system, wherein the propulsion system is deactivated in response to a user request.

[0013] In one aspect of the invention, the method comprises determining an expected electrical load based on the power supplied to the inverter via the DC bus.

[0014] In one aspect of the present invention, the first operating condition is that the vehicle power consumption value is less than a threshold value.

[0015] In one aspect of the present invention, the second operating condition is that the vehicle power consumption value is greater than the threshold.

[0016] In one aspect of the invention, the method includes indicating, via a human / machine interface, a decrease in the distance that the vehicle is capable of traveling in response to the second operating condition.

[0017] In one aspect of the invention, the method includes deactivating the second DC / DC converter in response to a threshold amount of time having passed since a most recent time the propulsion system was deactivated. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Advantages described herein will be more fully understood by reading the examples of embodiments herein referred to as the Detailed Description when read alone or with reference to the accompanying drawings, in which:

[0019] Figure 1 is a schematic view of an example electric vehicle;

[0020] Figure 2 is a schematic diagram of an example power distribution system;

[0021] Figure 3 is based on Figure 4 and Figure 5 An example power management sequence of the method; and

[0022] Figure 4 and Figure 5 A flow chart illustrating an example method of managing electrical power in a vehicle is shown. DETAILED DESCRIPTION

[0023] This specification relates to managing power in a vehicle. The vehicle may be an electric vehicle or a hybrid vehicle. The vehicle may include a traction battery and a lower voltage battery to supply power throughout the vehicle. In one example, the vehicle may be Figure 1 The electric vehicle shown. The vehicle may include Figure 2 The power distribution system shown in Figure 1 can be Figure 3 The sequence shown according to Figure 4 and Figure 5 A method for managing power from a power distribution system. A flow chart of a method for managing power in a vehicle is provided in Figure 4 and Figure 5 Shown in.

[0024] A vehicle may provide a user with AC and DC power outlets to power devices such as computers, coolers, game consoles, and other electrical devices. It may be desirable for a user to draw power from the vehicle's AC and / or DC power outlets while the vehicle is operating or when the vehicle's propulsion system has been deactivated in response to a key-off condition (e.g., a condition in which a vehicle user provides a request to deactivate the vehicle's propulsion source to prevent vehicle movement and / or conserve vehicle power; note that a key may not be required for a key-off condition). If the AC and / or DC power outlets provide power while the vehicle is in the key-off state, the user may not be aware that utilizing power from the AC and / or DC power outlets may reduce the vehicle's battery state of charge (SOC), thereby reducing the vehicle's available driving range. Therefore, it may be desirable to notify the user that the vehicle's available driving range may be reduced and manage the vehicle's power so that the vehicle's available driving range can remain high.

[0025] The inventors of this document have recognized the above-mentioned problems and have developed a vehicle power system, which includes: a first DC / DC converter; a second DC / DC converter, the second DC / DC converter having a higher power output capacity than the first DC / DC converter; and one or more controllers, the one or more controllers including executable instructions for causing the one or more controllers to deactivate or keep deactivating the second DC / DC converter and activate or keep activating the first DC / DC converter after a vehicle key-off event and in response to a first operating condition, and executable instructions for causing the one or more controllers to deactivate or keep deactivating the first DC / DC converter and activate or keep activating the second DC / DC converter after the vehicle key-off event and in response to a second operating condition.

[0026] By selecting which of the two DC / DC converters to activate after a vehicle key-off condition, a technical result can be achieved by reducing power consumption and supplying sufficient power to power-consuming devices after a vehicle key-off condition. Consequently, power can be managed so that less power, which could be used to propel the vehicle, is consumed to power accessories. Consequently, the vehicle's ability to continue driving can be at least partially maintained.

[0027] The present disclosure can provide several advantages. Specifically, the method can reduce power consumption after the vehicle key is turned off. Furthermore, the method can scale power output with power consumption to improve power distribution efficiency. Furthermore, the method attempts to maintain the vehicle's ability to travel further while powering accessory electrical devices.

[0028] The above advantages and other advantages and features of the present specification will be readily apparent from the following detailed description when taken alone or in conjunction with the accompanying drawings.

[0029] It will be understood that the above summary is provided to introduce a series of concepts further described in the detailed description in a simplified form. It is not meant to identify key features of the claimed subject matter, the scope of which is solely defined by the claims appended to the detailed description. Furthermore, the claimed subject matter is not limited to implementations that address any disadvantages noted above or in any part of this disclosure.

[0030] Figure 1 1 is a block diagram of a vehicle 121 including a powertrain or driveline 100. The front of the vehicle 121 is indicated at 110, and the rear of the vehicle 121 is indicated at 111. The driveline 100 includes an electric machine 126. The electric machine 126 may consume or generate electric power depending on its operating mode. Figure 1 , mechanical connections between various components are shown as solid lines, while electrical connections between various components are shown as dashed lines.

[0031] The powertrain 100 includes a rear axle 122 . In some examples, the rear axle 122 may include two half-shafts, such as a first half-shaft 122 a and a second half-shaft 122 b . The powertrain 100 also includes front wheels 130 and rear wheels 131 . The rear wheels 131 may be driven by the motor 126 .

[0032] The rear axle 122 is coupled to a motor 126. The rear drive unit 136 can transfer power from the motor 126 to the axle 122, thereby rotating the rear wheels 131. The rear drive unit 136 can include a low range 175 and a high range 177 coupled to the motor 126 via an output shaft 126o of the motor 126. The low range 175 can be engaged via a fully closed low range clutch 176. The high range 177 can be engaged via a fully closed high range clutch 178. The high range clutch 178 and the low range clutch 176 can be opened and closed via commands received by the rear drive unit 136 over the network 199. Alternatively, the high range clutch 178 and the low range clutch 176 can be opened and closed via a digital output or pulse width provided by the control system 114. The rear drive unit 136 can include a differential 128 so that torque can be provided to the first half-shaft 122a and the second half-shaft 122b. In some examples, an electronically controlled differential clutch (not shown) may be included in rear drive unit 136 .

[0033] The motor 126 can receive power from an onboard electrical energy storage device 132. In addition, the motor 126 can provide a generator function to convert the vehicle's kinetic energy into electrical energy, where the electrical energy can be stored at the electrical energy storage device 132 for later use by the motor 126. The inverter 134 can convert the alternating current generated by the motor 126 into direct current for storage at the electrical energy storage device 132, and vice versa. The electric drive system 135 includes the motor 126 and the inverter 134. The electrical energy storage device 132 can be a traction battery (e.g., a battery that supplies power to propel the vehicle), a capacitor, an inductor, or other electrical energy storage device. The power flowing into the electric drive system 135 can be monitored via a current sensor 145 and a voltage sensor 146. The position and speed of the motor 126 can be monitored via a position sensor 147. The torque generated by the motor 126 can be monitored via a torque sensor 148.

[0034] In some examples, electrical energy storage device 132 can be configured to store electrical energy that can be provided to other electrical loads resident on the vehicle (in addition to the motor), including cabin heating and air conditioning systems, engine starting systems, headlight systems, cabin audio and video systems, etc.

[0035] Control system 114 may communicate with electric motor 126, electrical energy storage device 132, and the like. Control system 114 may receive sensory feedback information from electric drive system 135, electrical energy storage device 132, and the like. Furthermore, control system 114 may send control signals to electric drive system 135, electrical energy storage device 132, and the like in response to this sensory feedback. Control system 114 may receive an indication of an operator-requested output of the vehicle propulsion system from human operator 102 or an autonomous controller. For example, control system 114 may receive sensory feedback from pedal position sensor 194 in communication with pedal 192. Pedal 192 may schematically represent a driver demand pedal. Similarly, control system 114 may receive an indication of an operator-requested vehicle deceleration via human operator 102 or an autonomous controller. For example, control system 114 may receive sensory feedback from pedal position sensor 157 in communication with vehicle deceleration pedal 156.

[0036] The electrical energy storage device 132 may periodically receive electrical energy from a power source residing external to the vehicle (e.g., not part of the vehicle), such as a stationary power grid (not shown). As a non-limiting example, the powertrain 100 may be configured as a plug-in electric vehicle (EV), whereby electrical energy may be supplied to the electrical energy storage device 132 via a power grid (not shown).

[0037] The electrical energy storage device 132 includes an electrical energy storage device controller 139. The electrical energy storage device controller 139 can provide charge balancing between energy storage elements (e.g., battery cells) and communication with other vehicle controllers (e.g., controller 112). The electrical energy storage device 132 is electrically coupled to a first direct current (DC) / DC converter 153 (e.g., a lower capacity DC / DC converter (100 watts)) and a second DC / DC converter 137 (e.g., a higher capacity DC / DC converter (4000 watts)). The first DC / DC converter 153 and the second DC / DC converter 137 can be bidirectional. The first DC / DC converter 153 and the second DC / DC converter 137 are electrically coupled to a power distribution module 138. A lower voltage battery 155 (e.g., a 12 volt battery) is also electrically coupled to the power distribution module 138.

[0038] One or more wheel speed sensors (WSS) 195 may be coupled to one or more wheels of the drivetrain 100. The wheel speed sensor may detect the rotational speed of each wheel. Such an example of a WSS may include a permanent magnet type sensor.

[0039] Controller 112 may include part of a control system 114. In some examples, controller 112 may be a single controller for the vehicle. Control system 114 is shown receiving information from a plurality of sensors 116 (various examples of which are described herein) and sending control signals to a plurality of actuators 181 (various examples of which are described herein). As one example, sensors 116 may include tire pressure sensors (not shown), wheel speed sensors 195, and the like. In some examples, sensors associated with motor 126, wheel speed sensors 195, and the like may transmit information regarding various states of motor operation to controller 112. Controller 112 includes non-transitory (e.g., read-only memory) 165, random access memory 166, digital input / output 168, and a microcontroller 167. Infotainment system 140 (e.g., a human / machine interface) may receive input data from person 102 and may display messages and data to person 102. The infotainment system 140 may communicate with the controller 112 and the power distribution module 138 via a network 199 , such as a controller area network (CAN) or Ethernet network.

[0040] Now refer to Figure 2 , a detailed schematic diagram of an example power distribution system 200 including the power distribution module 138 is shown. Figure 2 Electrical connections between the various components shown are shown as dashed lines.

[0041] The power distribution module 138 includes a plurality of switches 252 to 266 for selectively electrically isolating power consuming devices and power sources from a DC bus 210 (e.g., a low-voltage (12-volt) bus). The switches 252 to 266 can be solid-state devices or devices comprising physical contacts. The lower-voltage battery 155 can be selectively coupled to the DC bus 210 via a contactor 250. The contactor 250 is shown in a closed state, allowing current to flow through the contactor. The electric power steering system 202 can be selectively electrically coupled to the low-voltage bus (e.g., a metal strip or strip that facilitates power transfer) 210 via the switch 252. The switch 252 is shown in an open state. The ultracapacitor 204 can be selectively electrically coupled to the DC bus 210 via the switch 254. The switch 254 is shown in an open state. The electric vehicle deceleration actuator 206 (e.g., a brake caliper actuator) can be selectively electrically coupled to the DC bus 210 via the switch 256. The switch 256 is shown in an open state. Infotainment system 140 can be selectively electrically coupled to DC bus 210 via switch 258. Switch 258 is shown in the open state. Inverter 285 can be selectively electrically coupled to DC bus 210 via switch 260. Switch 260 is shown in the open state. Second DC / DC converter 137 can be selectively electrically coupled to DC bus 210 via capacitor 280. Contactor 280 is shown in the open state. Second DC / DC converter 153 can be selectively electrically coupled to DC bus 210 via switch 262. Switch 262 is shown in the open state. Headlights 212 can be selectively electrically coupled to DC bus 210 via switch 264. Switch 264 is shown in the open state. Climate control system 214 can be selectively electrically coupled to DC bus 210 via switch 266. Switch 266 is shown in the open state.

[0042] The first DC / DC converter and the second DC / DC converter receive power from the traction battery and reduce the DC voltage from a higher voltage (e.g., >400 volts) to a lower voltage (e.g., between 12 volts and 14 volts). The DC / DC converters can supply DC power to the DC bus 210 to power lower voltage DC power consuming devices.

[0043] Inverter 285 can convert DC power from DC bus 210 into AC power to supply AC power to user accessories 286 (e.g., powered coolers, fans, computers, games, etc.) The DC power can be stepped up to a higher voltage (e.g., 110 volts) to generate AC power.

[0044] The power distribution module 138 includes a controller 270 for sensing the voltage of the DC bus 210 and selectively opening and closing switches 252 to 266 and contactors 250 and 280. The controller 270 includes a processor 273, a memory 272 (e.g., read-only memory, random access memory, keep-alive memory, etc.), and inputs and outputs 271 (e.g., an analog-to-digital converter, digital inputs and outputs). The controller 270 may also receive input from sensors 290 via the inputs and outputs 271. The sensors 290 may include, but are not limited to, current sensors for each device coupled to the DC bus 210 and lines for DC voltage sensing of the DC bus 210. The controller 270 may estimate the power consumed or provided by each device electrically coupled to the DC bus 210.

[0045] therefore, Figure 1 and Figure 2A system provides a vehicle power system, the vehicle power system comprising: a first DC / DC converter; a second DC / DC converter having a higher power output capacity than the first DC / DC converter; and one or more controllers, the one or more controllers including executable instructions for causing the one or more controllers to deactivate or maintain deactivation of the second DC / DC converter and activate or maintain activation of the first DC / DC converter after a vehicle key-off event and in response to a first operating condition, and executable instructions for causing the one or more controllers to deactivate or maintain deactivation of the first DC / DC converter and activate or maintain activation of the second DC / DC converter after the vehicle key-off event and in response to a second operating condition. In a first example, the vehicle power system includes: wherein the first operating condition is a vehicle power consumption value less than a threshold value. In a second example, which may include the first example, the vehicle power system includes: wherein the second operating condition is a vehicle power consumption value greater than the threshold value. In a third example, which may include one or both of the first and second examples, the vehicle power system includes: wherein the first and second DC / DC converters are electrically coupled to a traction battery. In a fourth example, which may include one or more of the first to third examples, the vehicle power system includes: wherein the first DC / DC converter and the second DC / DC converter are electrically coupled to a first voltage bus and a second voltage bus, the first voltage bus being configured to transmit a lower voltage than the second voltage bus. In a fifth example, which may include one or more of the first to fourth examples, the vehicle power system further includes additional executable instructions that cause the one or more controllers to indicate, via a human / machine interface, a likelihood of a decrease in available vehicle range in response to activating or maintaining activation of the second DC / DC converter. In a sixth example, which may include one or more of the first to fifth examples, the vehicle power system further includes additional executable instructions that cause the one or more controllers to monitor power consumption of an inverter prior to the vehicle key-off event and determine the first operating condition or the second operating condition based on the power consumption of the inverter.

[0046] in addition, Figure 1 and Figure 2A system provides a vehicle power system, the vehicle power system comprising: a first battery; a traction battery; a first DC / DC converter; a second DC / DC converter; an inverter; a power distribution system, the power distribution system comprising a power distribution bus, the first battery selectively coupled to the power distribution bus via a first contactor, the first DC / DC converter selectively coupled to the power distribution bus via a switch, the second DC / DC converter selectively coupled to the power distribution bus via a second contactor, the inverter selectively coupled to the power distribution bus via a second switch; and one or more controllers, the one or more controllers including executable instructions for causing the one or more controllers to deactivate or maintain deactivation of the second DC / DC converter and activate or maintain activation of the first DC / DC converter following a request to deactivate the vehicle propulsion system and in response to a first operating condition, and executable instructions for causing the one or more controllers to deactivate or maintain deactivation of the first DC / DC converter and activate or maintain activation of the second DC / DC converter following a request to deactivate the vehicle propulsion system and in response to a second operating condition. In a first example, the vehicle power system includes: wherein the first operating condition and the second operating condition are based on a maximum amount of power consumed by an inverter when the vehicle propulsion system is activated. In a second example, which may include the first example, the vehicle power system includes: wherein the first operating condition and the second operating condition are based on a change in power consumed by the inverter when the vehicle propulsion system is deactivated. In a third example, which may include one or both of the first and second examples, the vehicle power system further includes a human / machine interface and additional executable instructions for deactivating the second DC / DC converter in response to a user request to deactivate the second DC / DC converter. In a fourth example, which may include one or more of the first to third examples, the vehicle power system further includes a human / machine interface and additional executable instructions for indicating a decrease in the distance that the vehicle can travel via the human / machine interface in response to the second operating condition.

[0047] Now refer to Figure 3 , showing that according to Figure 4 and Figure 5 An example power distribution sequence of the method. Figure 3 An example can be found via Figure 1 and Figure 2 System collaboration Figure 4 and Figure 5 method to provide. Figure 3 The plots are aligned in time. The vertical lines indicate the times of interest in the sequence.

[0048] from Figure 3 The first graph starting from the top is via an inverter (e.g. Figure 2FIG285 is a graph of power consumed from a DC bus versus time. The vertical axis represents power consumed by the inverter to power the AC device, with the amount of power increasing in the direction of the vertical axis arrow. The horizontal line represents time, with time increasing from the left side of the graph to the right side of the graph. Trace 302 represents the power consumed by the inverter.

[0049] from Figure 3 The second graph starting from the top of the graph is a graph of the operating state of the first DC / DC converter (e.g., a converter with lower power output capacity) versus time. The vertical axis represents the operating state of the first DC / DC converter, and when trace 304 is at a higher level near the vertical axis arrow, the first DC / DC converter is activated (e.g., outputting a DC voltage). When trace 304 is at a lower level near the horizontal axis, the first DC / DC converter is not activated (e.g., not outputting a DC voltage). The horizontal line represents time, and time increases from the left side of the graph to the right side of the graph. Trace 304 represents the operating state of the first DC / DC converter.

[0050] from Figure 3 The third graph, starting from the top of the graph, is a graph of the operating state of the second DC / DC converter (e.g., a converter with a higher power output capacity) versus time. The vertical axis represents the operating state of the second DC / DC converter, and when trace 306 is at a higher level near the vertical axis arrow, the second DC / DC converter is activated (e.g., outputting a DC voltage). When trace 306 is at a lower level near the horizontal axis, the second DC / DC converter is not activated (e.g., not outputting a DC voltage). The horizontal line represents time, and time increases from the left side of the graph to the right side of the graph. Trace 306 represents the operating state of the second DC / DC converter.

[0051] from Figure 3 The fourth graph from the top is a graph of vehicle key-on status versus time. The vertical axis represents the vehicle key-on operational state, and when trace 308 is at a higher level near the vertical axis, the vehicle key-on state is active. When trace 308 is at a lower level near the horizontal axis, the vehicle key-on state is inactive. The horizontal line represents time, and time increases from the left side of the graph to the right side. Trace 308 represents the vehicle key-on state.

[0052] Vehicle key-on is a condition in which power is supplied to the vehicle propulsion system and the vehicle propulsion system is ready to propel the vehicle, but further actions may be required for the vehicle to be propelled, such as placing the vehicle in drive and releasing the wheel brake calipers. Vehicle key-on does not require an actual key. Instead, a key, phone or other remote activation device, button, etc. can initiate the vehicle key-on condition and / or cause the vehicle to exit the key-on state.

[0053] from Figure 3 The fifth graph, starting from the top, plots the estimated power consumed from the DC bus by all power consuming devices electrically coupled to the DC bus versus time after the vehicle key is turned off. The vertical axis represents the power consumed by all power consuming devices electrically coupled to the DC bus, with the amount of power consumed increasing in the direction of the vertical axis arrow. The horizontal line represents time, with time increasing from the left side of the graph to the right side. Trace 310 represents the estimated power consumed by all devices coupled to the DC bus. Trace 350 represents the maximum amount of power that the first DC / DC converter can supply to the DC bus.

[0054] from Figure 3 The sixth graph, starting from the top, plots the actual amount of power consumed from the DC bus by all power consuming devices electrically coupled to the DC bus versus time. The vertical axis represents the actual amount of power consumed by all power consuming devices electrically coupled to the DC bus, with the amount of power consumed increasing in the direction of the vertical axis arrow. The horizontal line represents time, with time increasing from the left side of the graph to the right side. Trace 312 represents the actual power consumed by all devices coupled to the DC bus. Trace 350 represents the maximum amount of power that the first DC / DC converter can supply to the DC bus.

[0055] At time t0, the vehicle is turned on, as indicated by the vehicle key-on state, and the inverter consumes a small amount of power. The first DC / DC converter and the second DC / DC converter are activated. Both DC / DC converters are activated during the key-on condition so that either can supply DC power to the DC bus. However, the first DC / DC converter is configured to deliver a lower voltage of 12.2 volts, and the second DC / DC converter is configured to supply 12.5 volts. If the second DC / DC converter becomes degraded and if it cannot support 12.2 volts, the first DC / DC converter supplies power to maintain 12.2 volts for a predetermined amount of time during the key-on period. When the second DC / DC converter supplies DC power to the DC bus, the first DC / DC converter does not supply power to the bus, but the first DC / DC converter remains activated. The estimated power consumed after the key is turned off is not indicated, and the actual DC power consumption from the DC bus is above threshold 352.

[0056] At time t1, the vehicle remains in the key-on state, but the amount of power consumed by the inverter increases due to an intermittent load increase. The operating states of the first and second DC / DC converters remain unchanged, and no estimated power consumption after key-off is indicated. The actual DC power consumption level increases as the inverter power consumption increases. This increase in inverter power consumption ends at time t2.

[0057] At time t3, the vehicle exits the key-on state, and the estimated power consumption after key-off is output at a level above threshold 350. The second DC / DC converter remains activated so that the expected electrical load can be powered by the higher capacity DC / DC converter. The first DC / DC converter remains activated while waiting for a predetermined amount of time (e.g., time t3) to pass since the last key-off. The actual DC power consumption level remains above threshold 352, but it drops below threshold 352 between time t3 and time t4. The actual DC power consumption is measured and / or monitored between time t3 and time t4 (the predetermined amount of time) to allow the user to unplug devices that consume power from the DC bus and to account for the power reduction in the estimated power consumption level after key-off.

[0058] At time t4, a predetermined amount of time has passed since the most recent key-off (e.g., time t3), so the change in actual DC power consumed between time t3 and time t4 is applied to adjust the estimated power consumed after key-off to below threshold 350. Since the estimated consumed power is now below threshold 350, the second DC / DC converter is deactivated and the first DC / DC converter remains activated so that the DC power requirement can be met. Deactivating the second DC / DC converter reduces DC power consumption because the first DC / DC converter operates more efficiently at power levels below threshold 350.

[0059] Between time t5 and time t6, the inverter power load increases as it did between time t1 and time t2, but this increase has been applied to generate an estimated power consumption value after the key-off value that is below the threshold value 350. Therefore, there can be a higher degree of confidence that the first DC / DC converter can meet the power demand without having to keep the second DC / DC converter active. Therefore, the first DC / DC converter remains active and provides an increase in the DC power consumed.

[0060] In this way, the power system can select between the two DC / DC converters which DC / DC converter to activate during a key-off condition.If the DC load increases above threshold 350 during a key-off condition, the second DC / DC converter can be activated to meet the increased electrical load.

[0061] Now refer to Figure 4 and Figure 5 , a method for managing the power of a vehicle is shown. Specifically, Figure 4 and Figure 5 The method may be incorporated as executable instructions stored in a non-transitory memory of one or more controllers. Figure 1 and Figure 2 The method 400 may be executed by transforming the operation of devices and actuators in the physical world via one or more controllers. The one or more controllers may sense vehicle operating conditions via sensors as described herein and adjust actuators (e.g., human / machine interfaces, switches, contactors, etc.) to manage power distribution. The vehicle may start with the first DC / DC converter and the second DC / DC converter activated. Figure 4 and Figure 5 The method 400 may be performed via the controller 270, the controller 112, or a combination of these and / or other controllers.

[0062] At 402, method 400 monitors the power supply of an inverter (eg, Figure 2 The DC power consumption value (at 285) is monitored and / or stored in the controller memory. When the vehicle is in the key-on state, the DC power value is monitored and stored in the controller memory. The DC power value is monitored and stored in the memory during the vehicle key-on state so that the method 400 can use the most recent DC power value. The DC power value can be measured at predetermined time intervals, and the method 400 can identify the maximum DC power consumption (MaxDCInv) when the vehicle is activated in the key-on state during the predetermined time interval. The method 400 proceeds to 404.

[0063] At 404 , method 400 determines whether power was supplied to at least one vehicle propulsion component (eg, traction motor) via a DC bus (eg, Figure 2 210) minus the average DC power consumed by the inverter (e.g., Figure 2285). Method 400 can retrieve from controller memory the average DC power consumed via the DC bus during a previous vehicle key-off event or condition (AveKODC) minus the average DC power consumed by the inverter. The average DC power consumption value determined from the previous key-off condition can be useful for vehicles that may deactivate some power consuming devices when entering the key-off state. In other examples, method 400 can determine the average DC power consumed during a key-on condition for a system that may not deactivate DC power consuming devices in response to the vehicle entering the key-off state. Method 400 proceeds to 406.

[0064] At 406, method 400 determines whether the vehicle is in a key-off condition. When a user requests to deactivate the vehicle for driving purposes, a key-off condition or event may exist, but vehicle accessories (e.g., infotainment system, power windows, windshield wipers, etc.) may remain powered. Deactivating the vehicle for driving purposes may include stopping the supply of power to one or more propulsion devices (e.g., motor or inverter). The user may request a key-off via a physical key, a phone, or other remote radio frequency device or button. If method 400 determines that a key-off has been requested, the answer is yes and method 400 proceeds to 408. Otherwise, method 400 returns to 406.

[0065] At 408, method 400 begins monitoring the amount of DC power from the DC bus consumed after the key is turned off for a predetermined amount of time. Method 400 can multiply the DC flowing through the DC bus by the voltage of the DC bus to determine the DC power. The amount of DC power can be determined at fixed time intervals (e.g., once per second) to determine whether the amount of power consumed via the DC bus is reduced after the key is turned off. If the user decouples a device powered by the DC bus, the power consumed via the DC bus may be reduced. For example, a computer can receive power when the vehicle is activated via a DC power outlet. The user can decouple the computer to remove the computer from the vehicle after the vehicle key is turned off. Step 408 allows the controller to determine the reduction in DC power consumption via the DC bus during this and similar situations so that the DC power consumption value is not overestimated. Method 400 can determine the power reduction by subtracting the DC power consumption value from the DC bus just before the vehicle enters the key-off state from the current DC power consumption value from the DC bus. The key-off power reduction can be determined via the following equation:

[0066] DCPowRed=DCPowKON-DCPowKOFF

[0067] Wherein DCPowRed is a DC power consumption reduction value when the vehicle is in a key-off state, DCPowKON is a DC power consumption value when the vehicle is in a key-on state, and DCPowKOFF is a DC power consumption value when the vehicle is in a key-off state. Method 400 proceeds to 410 .

[0068] At 410 , method 400 estimates the key-off power consumed from a DC bus (eg, a DC electrical load). In one example, method 400 may estimate the key-off power consumed from the DC bus via the following equation:

[0069] ExDCKO=AveKODE+MaxDCInv-DCPowRed

[0070] Where ExDCKO is the estimated or expected DC power consumed via the DC bus when the vehicle is in the key-off state, and MaxDCInv is the DC power expected to be consumed by the inverter (e.g., Figure 2 285) is the maximum DC power consumed, and DCPowRed is the DC power consumption reduction value when the vehicle is in the key-off state. Method 400 proceeds to 412.

[0071] At 412, method 400 determines whether the estimated or expected DC power consumed via the DC bus is greater than a threshold power level for activating the second DC / DC converter. In one example, the threshold power level is based on the continuous power output rating of the first DC / DC converter. If method 400 determines that the expected DC power consumed via the DC bus by the DC power consuming device is greater than the threshold, the answer is yes and method 400 proceeds to 430. Otherwise, the answer is no and method 400 proceeds to 414.

[0072] At 414, method 400 activates or maintains activation of the first DC / DC converter (e.g., the lower output DC / DC converter) and deactivates the second DC / DC converter (e.g., the higher output DC / DC converter). By deactivating the second DC / DC converter, the power consumed from the traction battery during the key-off condition can be reduced, such that the distance the vehicle can travel under power from the traction battery can be reduced compared to if the second DC / DC converter continued to operate during the key-off condition. Additionally, method 400 can measure and store in memory the average amount of DC power consumed by DC power consuming devices via the DC bus for a predetermined amount of time after the second DC / DC converter is deactivated (represented by a variable AveKODC). Method 400 proceeds to 414.

[0073] At 416 , method 400 judges whether the electrical load (eg, the amount of power consumed) from the DC bus exceeds a threshold amount of power. If so, the answer is yes and method 400 proceeds to 420 .

[0074] At 418, method 400 determines whether the first DC / DC converter has been activated for more than a threshold amount of time since the most recent key-off event. If so, the answer is yes and method 400 proceeds to 418. Otherwise, the answer is no and method 400 returns to 414.

[0075] At 420 , method 400 deactivates the first DC / DC converter so that the first DC / DC converter may not continuously drain the traction battery until the next key-on condition. Method 400 proceeds to exit.

[0076] At 422, method 400 provides an indication to the vehicle user that the vehicle's higher output capacity DC / DC converter is active and that the vehicle's range may be reduced due to operating the higher output DC / DC converter. Method 400 may also deactivate the higher output capacity DC / DC converter for a predetermined amount of time (e.g., 5 hours) after the most recent key-off event. Method 400 proceeds to exit.

[0077] At 430, method 400 provides an indication to the vehicle user that the vehicle's higher output capacity DC / DC converter is active and that the vehicle's range may be reduced due to operating the higher output DC / DC converter. Additionally, method 400 may request user input to determine whether the user wishes to maintain activation of the higher output DC / DC converter. Method 400 proceeds to 432.

[0078] At 432, method 400 determines whether the user wishes the second or higher capacity DC / DC converter to be active during the current key-off period. Method 400 may base this determination on user input to the human / machine interface. If method 400 determines that the user wishes to deactivate the higher capacity DC / DC converter during the current key-off period, the answer is yes and method 400 proceeds to 436. Otherwise, the answer is no and method 400 proceeds to 434.

[0079] At 434, method 400 maintains activation or activates the second or higher capacity DC / DC converter and deactivates the first or lower capacity DC / DC converter. Method 400 may also deactivate the second DC / DC converter for a predetermined amount of time (e.g., 5 hours) after the most recent key-off condition to conserve power. Method 400 proceeds to exit.

[0080] At 434, method 400 deactivates the second or higher capacity DC / DC converter and deactivates the first or lower capacity DC / DC converter. The first or lower capacity DC / DC converter is deactivated because the first or lower capacity DC / DC converter may not have sufficient output capacity to support the DC electrical load on the DC bus when the second DC / DC converter is deactivated. Method 400 proceeds to exit.

[0081] Thus, method 400 manages the operation of the DC / DC converter so that sufficient power is available to the DC electrical loads on the DC bus while compensating for DC / DC converter efficiency and output capacity. Additionally, for situations where a user may not wish to reduce the range that the vehicle can travel based on the current energy level stored in the traction battery, method 400 provides for user input to override automatic power management.

[0082] therefore, Figure 4 and Figure 5 A method for managing power in a vehicle is provided, the method comprising: activating or maintaining activation of a first DC / DC converter and deactivating or maintaining deactivation of a second DC / DC converter, via one or more controllers, after deactivating a propulsion system of the vehicle and in response to a first operating condition. In a first example, the method further comprises, via the one or more controllers, deactivating or maintaining deactivation of the first DC / DC converter and activating or maintaining activation of the second DC / DC converter, after deactivating the propulsion system of the vehicle and in response to a second operating condition. In a second example, which may include the first example, the method further comprises monitoring the amount of power supplied to an inverter via a DC bus after deactivating the propulsion system, wherein the propulsion system is deactivated in response to a user request. In a third example, which may include one or both of the first and second examples, the method further comprises determining an expected electrical load based on the power supplied to the inverter via the DC bus. In a fourth example, which may include one or more of the first to third examples, the method comprises: wherein the first operating condition is a vehicle power consumption value less than a threshold value. In a fifth example, which may include one or more of the first to fourth examples, the method comprises: wherein the second operating condition is a vehicle power consumption value greater than the threshold value. In a sixth example, which may include one or more of the first through fifth examples, the method further includes indicating, via a human / machine interface, a decrease in the distance the vehicle can travel in response to the second operating condition. In a seventh example, which may include one or more of the first through sixth examples, the method further includes deactivating the second DC / DC converter in response to a threshold amount of time having passed since a last time the propulsion system was deactivated.

[0083] It should be noted that the example control and estimation routines included herein can be used with various vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in non-transitory memory and can be executed by a control system including one or more controllers in combination with various sensors, actuators, and other engine hardware. The specific routines described herein can represent one or more of any number of processing strategies (such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc.). Therefore, the various actions, operations, and / or functions shown can be performed in the sequence shown, in parallel, or omitted in some cases. Similarly, the processing order is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the actions, operations, and / or functions shown can be repeatedly performed depending on the specific strategy used. In addition, at least a portion of the described actions, operations, and / or functions can graphically represent code to be programmed into the non-transitory memory of a computer-readable storage medium in the control system. When the described actions are performed by executing instructions in combination with one or more controllers in a system including various engine hardware components, the control actions can also transform the operating state of one or more sensors or actuators in the physical world.

[0084] This specification ends here. Without departing from the spirit and scope of this specification, those skilled in the art will think of many variations and modifications after reading this specification. For example, electric and hybrid vehicle configurations may benefit from using this specification.

[0085] According to the present invention, a vehicle power system is provided, comprising: a first battery; a traction battery; a first DC / DC converter; a second DC / DC converter; an inverter; a power distribution system, the power distribution system comprising a power distribution bus, the first battery being selectively coupled to the power distribution bus via a first contactor, the first DC / DC converter being selectively coupled to the power distribution bus via a switch, the second DC / DC converter being selectively coupled to the power distribution bus via a second contactor, and the inverter being selectively coupled to the power distribution bus via a second switch; and one or more controllers comprising executable instructions for causing the one or more controllers to deactivate or maintain deactivation of the second DC / DC converter and activation or maintenance of activation of the first DC / DC converter following a request to deactivate the vehicle propulsion system and in response to a first operating condition, and executable instructions for causing the one or more controllers to deactivate or maintain deactivation of the first DC / DC converter and activation or maintenance of activation of the second DC / DC converter following a request to deactivate the vehicle propulsion system and in response to a second operating condition.

[0086] According to one embodiment, the first operating condition and the second operating condition are based on a maximum amount of power consumed by the inverter when the vehicle propulsion system is activated.

[0087] According to one embodiment, the first operating condition and the second operating condition are based on changes in power consumed by the inverter when the vehicle propulsion system is deactivated.

[0088] According to one embodiment, the invention also features a human / machine interface and additional executable instructions for deactivating the second DC / DC converter in response to a user request to deactivate the second DC / DC converter.

[0089] According to one embodiment, the invention also features a human / machine interface and additional executable instructions for indicating, via the human / machine interface, a decrease in the distance the vehicle can travel in response to the second operating condition.

Claims

1. A vehicle power system comprising: a first DC-DC converter; a second DC / DC converter having a higher power output capacity than the first DC / DC converter; as well as One or more controllers including executable instructions that cause the one or more controllers to deactivate or maintain deactivation of the second DC / DC converter and activate or maintain activation of the first DC / DC converter after a vehicle key-off event and in response to a first operating condition, and executable instructions that cause the one or more controllers to deactivate or maintain deactivation of the first DC / DC converter and activate or maintain activation of the second DC / DC converter after the vehicle key-off event and in response to a second operating condition. 2 . The vehicle power system according to claim 1 , wherein the first operating condition is that the vehicle power consumption value is less than a threshold value. 3 . The vehicle power system according to claim 2 , wherein the second operating condition is that the vehicle power consumption value is greater than the threshold value.

4. The vehicle power system of claim 1, wherein the first DC / DC converter and the second DC / DC converter are electrically coupled to a traction battery. 5 . The vehicle power system of claim 1 , wherein the first DC / DC converter and the second DC / DC converter are electrically coupled to a first voltage bus and a second voltage bus, the first voltage bus being configured to deliver a lower voltage than the second voltage bus.

6. The vehicle power system of claim 1 , further comprising additional executable instructions that cause the one or more controllers to indicate, via a human / machine interface, a likelihood of a decrease in available vehicle range in response to activating or maintaining activation of the second DC / DC converter.

7. The vehicle power system of claim 1 , further comprising additional executable instructions causing the one or more controllers to monitor power consumption of an inverter prior to the vehicle key-off event and determine the first operating condition or the second operating condition based on the power consumption of the inverter.

8. A method of managing electrical power in a vehicle, comprising: Via one or more controllers, the first DC / DC converter is activated or maintained activated and the second DC / DC converter is deactivated or maintained deactivated after deactivating a propulsion system of the vehicle and in response to a first operating condition.

9. The method of claim 8, further comprising, via the one or more controllers, deactivating or maintaining deactivation of the first DC / DC converter and activating or maintaining activation of the second DC / DC converter after deactivating the propulsion system of the vehicle and in response to a second operating condition.

10. The method of claim 9, further comprising monitoring the amount of power supplied to the inverter via the DC bus after deactivating the propulsion system, wherein the propulsion system is deactivated in response to a user request.

11. The method of claim 10, further comprising determining an expected electrical load based on the power supplied to the inverter via the DC bus. 12 . The method of claim 11 , wherein the first operating condition is that a vehicle power consumption value is less than a threshold value. 13 . The method of claim 12 , wherein the second operating condition is that the vehicle power consumption value is greater than the threshold.

14. The method of claim 13, further comprising indicating a decrease in the distance the vehicle can travel via a human / machine interface in response to the second operating condition. 15 . The method of claim 14 , further comprising deactivating the second DC / DC converter in response to a threshold amount of time having passed since a last time the propulsion system was deactivated.

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