Vehicle braking system and method and electric vehicle

Abstract

A vehicle braking system and method, and an electric vehicle, the system comprising one or more traction motors and an electrical device electrically connected to the one or more traction motors. The one or more traction motors are configured to propel the vehicle and generate electricity during reverse downhill travel of the vehicle. The electrical device is configured to consume the electricity generated by the reverse movement of the vehicle by performing work using the electricity during reverse travel of the vehicle.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is a non-provisional conversion of, and claims priority to, U.S. Provisional Application No. 63 / 069,873, filed on August 25, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Embodiments of the present disclosure relate to converting the kinetic energy of a vehicle into electrical energy using a motor. Background Art

[0004] The traction motor of a vehicle propulsion system can be used to slow, arrest, or stop the movement of a vehicle by converting the kinetic energy of a moving vehicle (e.g., rolling wheels) into electrical energy using the motor as a generator, without relying on friction brakes. Motor braking can be used when a vehicle starting on a slope begins to slide down the slope after the brakes are released and before traction is generated to propel the vehicle in the direction of travel. If the vehicle's reverse motion is not slowed, the vehicle may slide down and hit another vehicle or other equipment, causing damage and posing a safety hazard. Motor braking is also typically used when the vehicle is traveling downhill or to offset gravity and slow the vehicle to a desired speed, without wearing out the friction brakes.

[0005] In certain types of vehicles (e.g., trains), the amount or rate of electrical energy generated by the motor during motor braking can potentially overload a conductive link or bus because more electrical energy is supplied to the conductive link than can be utilized by equipment electrically connected to the conductive link (e.g., batteries and other energy storage devices that store electrical energy for future use). Furthermore, oversupplying the conductive link with electrical energy can damage electrical equipment and even cause a fire. Some vehicles are equipped with additional components for the express purpose of absorbing excess electrical energy generated by the motor. The additional component may include at least one array or grid of resistive elements that dissipate the electrical energy as heat. Installing such components on a vehicle solely for the purpose of dissipating electrical energy inevitably increases the cost and weight of the vehicle and also takes up space, reducing the space available for other components, personnel, cargo, and / or the like. Summary of the Invention

[0006] In one or more embodiments, a system (e.g., a vehicle braking system) is provided that includes one or more traction motors and an electrical device configured to be electrically connected to the one or more traction motors. The one or more traction motors are configured to propel the vehicle and generate electricity during reverse downhill travel of the vehicle. The electrical device is configured to consume electricity generated by the reverse travel of the vehicle by performing work using the electricity during reverse travel of the vehicle.

[0007] In one or more embodiments, a method (e.g., for vehicle braking) is provided that includes generating electricity from a vehicle reversing downhill, and further includes consuming the electricity generated by the vehicle reversing by performing work using the electricity during the vehicle reversing.

[0008] In one or more embodiments, an electric vehicle is provided that includes a traction motor and a load. The traction motor is configured to generate electricity through regenerative braking during downhill travel of the electric vehicle. The load is incapable of storing the generated electricity. The load is configured to receive electricity and operate using the electricity generated by the regenerative braking during downhill travel of the electric vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present subject matter may be understood by reading the following description of non-limiting embodiments with reference to the accompanying drawings, in which:

[0010] Figure 1 A schematic diagram illustrating a vehicle motor brake system provided on a vehicle generating propulsion force according to an embodiment of the present disclosure;

[0011] Figure 2 shows a portion of a motor braking system according to an embodiment of the present disclosure;

[0012] Figure 3 is a graph showing changes in pressure over time in a vehicle air reservoir according to an embodiment of the present disclosure;

[0013] Figure 4 is a flowchart of a method for performing vehicle motor braking according to an embodiment of the present disclosure;

[0014] Figure 5 is a flow chart of a method for consuming power according to an embodiment of the present disclosure, which can be Figure 4 The motor braking method is implemented. DETAILED DESCRIPTION

[0015] One or more embodiments described herein relate to systems and methods for actively utilizing electrical energy generated during motor braking of a vehicle. For example, the systems and methods control the generation of electrical energy and the conduction of electrical energy to the vehicle so that the electrical energy is consumed by one or more electrical devices on the vehicle. The one or more electrical devices consume electrical energy by using the electricity to perform work during motor braking. The one or more electrical devices actively perform work by applying force to move a mechanical device or object, rather than passively dissipating electricity as heat, as in the case of a resistive dynamic brake grid. In an embodiment, the electricity generated by motor braking is used to power an auxiliary motor that moves a piston or group of pistons to compress air. In other embodiments, the electricity generated by motor braking can be used to power other electrical devices to cause a mechanical device or other object to move, i.e., to perform work.

[0016] The embodiments described herein are independent of the presence of a dynamic brake grid on a vehicle. For example, a motor brake system can be provided on a vehicle that does not include a resistor grid and associated hardware for dissipating the electricity generated by the motor as heat. Due to the absence of the resistor grid and associated hardware, such a vehicle can save cost, reduce weight and / or save space. In other embodiments, the motor brake system can be used on a vehicle that has a resistor grid. Use of the motor brake system and methods of using the system can reduce or completely eliminate the workload of the resistor grid by diverting power to one or more electrical devices that consume current to operate. By reducing the dissipation of energy as heat, a vehicle utilizing the motor brake system and methods described herein can reduce heat mitigation operations, such as by operating a blower, fan or other active cooling device less frequently.

[0017] In an embodiment, the vehicle does not have a resistance grid, and the motor-braking system limits the amount of power generated by the traction motor to a level that can be consumed by one or more auxiliary electrical devices on the vehicle during motor-braking operations. Because the power generated by the traction motor does not exceed the load that the auxiliary electrical devices can handle, all available power generated during motor-braking can be consumed by the auxiliary devices without having to store the power for later use or dissipate the power as heat. The motor-braking system is configured to achieve and maintain this balance between power supply to the traction motor and power consumption by the electrical devices to avoid rapid increases in voltage on the bus, also known as direct current (DC) link voltage overshoots.

[0018] Figure 1 FIG2 is a schematic diagram illustrating a vehicle motor-brake system 100 provided on a vehicle 102 generating propulsion according to an embodiment of the present disclosure; the vehicle generating propulsion (also referred to herein as a vehicle) is terrestrial and travels on a road 104. The vehicle includes a plurality of wheels 106 engaged with a road segment. The vehicle moves along the road by applying torque to at least some of the wheels to force the wheels in contact with the road to rotate.

[0019] In an embodiment, the vehicle may be a rail vehicle, such as a locomotive, and the road may be a railroad track. In other examples, the vehicle motor brake system may be provided on another type of vehicle, such as a truck (e.g., an on-highway semi-truck, a mining truck, a logging truck, etc.), an automobile, a bus, etc., and the road may be a paved road, an off-road road, etc. Although Figure 1 Not shown, but the vehicle may be coupled to one or more wheeled loads (eg, rail cars, trailers, or other non-propulsion generating vehicles) to pull and / or push the wheeled loads along a roadway.

[0020] The motor-brake system includes one or more traction motors 114 and one or more electrical devices 115 electrically coupled to the traction motors. The motor-brake system also includes a control circuit 122 or controller 122 on the vehicle, which is operably coupled to the one or more electrical devices and the one or more traction motors. The control circuitry represents hardware circuitry that includes and / or is coupled to one or more processors 124 (e.g., one or more microprocessors, integrated circuits, microcontrollers, field programmable gate arrays, etc.). The control circuitry includes and / or is coupled to a tangible and non-transitory computer-readable storage medium (e.g., memory) 126 disposed on the vehicle. For example, the memory may store program instructions (e.g., software) executed by the one or more processors to perform the operations of the control circuitry described herein. The memory may additionally or alternatively store various information, such as a route database, a trip table, a trip plan (which provides traction and braking settings associated with different locations along a route), vehicle parameters, etc. The control circuitry may control the traction motors to propel the vehicle during a traction (or drive) operating mode and to generate electrical power based on the movement of the vehicle during a motor-brake operating mode. The control circuitry may control the amount or rate at which the traction motor generates electrical power and / or may direct the electrical power to one or more electrical devices 115 that consume the electrical power by performing work during motor braking of the vehicle.

[0021] In one or more embodiments, one or more electrical devices that consume the generated power cannot store power to later power a load. In one example, one or more electrical devices may include auxiliary electrical devices 117 that do not generate propulsion, and the auxiliary electrical devices 117 that do not generate propulsion do not propel the vehicle (e.g., do not generate torque). The auxiliary electrical devices may include various electromechanical devices that use electricity to cause movement of mechanical devices or other objects. Non-limiting examples of electrical devices include compressors, pumps, motors, blowers, actuators, etc. The electrical devices may optionally be components of a heating, ventilation, and air conditioning (HVAC) system, a computing system, a lighting system, etc.

[0022] In another example, the one or more electrical devices that consume the generated electricity may include electrical devices that generate propulsion, such as traction motors. In the illustrated embodiment, the vehicle has two traction motors 114A and 114B. During traction mode, both traction motors can be used to generate torque to propel the vehicle. During motor braking mode, the first traction motor 114A can be controlled to generate electricity based on the kinetic energy of the vehicle, and the second traction motor 114B can represent an electrical device that is controlled to consume the electricity generated by the first traction motor. When the vehicle friction brakes are released, if a vehicle on a slope (e.g., a ramp) begins to slide down the slope in reverse, the second traction motor can use electricity to perform torque generation work, prompting the vehicle to climb the slope to resist rolling back. The second traction motor can generate torque to help prevent the vehicle from rolling back down the slope and / or propel the vehicle up the slope by generating propulsion as the work performed.

[0023] The vehicle includes an electric drive system that supplies and conducts electrical energy to propel the vehicle. The motor-brake system may utilize the electric drive system and include components of the electric drive system. The electric drive system includes a direct current (DC) bus or link 110, at least one power source capable of powering vehicle propulsion, an inverter 112, and traction motors 114. Each inverter is associated with a different corresponding traction motor. One exemplary power source on the vehicle is an energy storage device 116, which may include one or more battery cells, battery modules, capacitors, etc. Another exemplary power source is a fuel-fired internal combustion engine 118, which mechanically drives an alternator 120. The vehicle drive system in the illustrated embodiment is a hybrid vehicle system that includes an energy storage device as well as an engine and an alternator. In alternative embodiments, the vehicle may lack an energy storage device, or may include an energy storage device for powering auxiliary loads but not for vehicle propulsion. In a second alternative embodiment, the vehicle may be a fully electric vehicle without an engine and an alternator.

[0024] A DC bus electrically connects a power source to the inverter and associated traction motors. One or more auxiliary electrical devices are electrically connected to the DC bus. A control circuit can selectively open and close electrical switches (e.g., relays, contactors, etc.) on the DC bus to control which components can receive power from the DC bus and / or supply power to the DC bus at a given time. The control circuit can also generate control signals that are transmitted to the inverter to turn on and off the inverter's solid-state power components (e.g., transistors) to convert the DC power on the DC bus into another power waveform suitable for powering the associated traction motors. For example, the inverter can be configured to convert DC power to three-phase AC power for powering the AC traction motors. The traction motors are mechanically connected to the wheels via mechanical linkages (e.g., gears, shafts, etc.). During traction mode, the traction motors convert electrical energy into mechanical energy, which applies torque through the mechanical linkages to rotate the wheels.

[0025] exist Figure 1 In the embodiment of the present invention, a vehicle is located on a road section having a slope (e.g., an incline) relative to a horizontal line 130. Gravity urges the vehicle to move in a downhill direction 132. When the vehicle is on this road section, the vehicle can switch to a motor braking mode. In the motor braking mode, one or more traction motors are controlled to act as generators, thereby converting the kinetic energy of the vehicle moving in the downhill direction into electrical energy. For example, during vehicle movement, wheel rotation transmitted through the axles and mechanical linkages causes the rotor of the traction motor to rotate relative to the stator. The traction motor provides resistance to the wheels and mechanical linkages, thereby slowing the downhill movement of the vehicle. The rotation of the rotor relative to the stator generates electrical energy, which is delivered to the DC bus through the inverter.

[0026] In an embodiment, a motor braking system can control the amount and / or rate of power supplied to a DC bus from one or more traction motors and inverters. The supply of current generated to the DC bus during motor braking is monitored and controlled to avoid exceeding the voltage and / or current carrying capacity of the DC bus and the voltage and / or current consumption capacity of electrical devices that utilize the power for operation. In addition, the motor braking system can control the power consumption on the DC bus by one or more electrical devices that consume power during the motor braking operating mode. The motor braking system balances the generation and consumption of power within a tolerance range during motor braking so that almost all of the power generated is consumed without dissipating the current as heat through a resistor grid. For example, the generated current is supplied to the DC bus to maintain a specified link voltage or voltage range on the DC bus. At the same time, the electrical devices are operated to draw current from the DC bus. The current consumption rate is balanced with the current supply rate to maintain the DC bus at a specified link voltage or within a specified voltage range. During motor braking, the electrical devices consume substantially all of the power generated by the traction motors such that no current is intentionally dissipated as heat through the resistive grid, although a small amount of current may be dissipated as heat along the DC bus and other conductive paths due to inherent resistance in conductive components (e.g., wires, switches, etc.). Substantially all of the power generated can represent at least one threshold level, such as at least 95%, at least 96%, at least 97%, at least 98%, or at least 99%, of the total power generated by the traction motors during motor braking operations.

[0027] In conventional vehicles capable of motor braking, the electricity generated by the traction motor can be used to charge the energy storage device and power the auxiliary loads, and any excess current provided to the bus is directed to the dynamic brake grid for dissipation of the electricity as heat. Because the grid dissipates the excess current, the amount of current drawn by the motor is not monitored or controlled. The motor braking system described herein does not utilize a resistive grid to dissipate the excess current as heat. For example, Figure 1 The vehicle in the present invention may not even include an installed resistance grid. In addition, electricity may be generated in an amount and / or at a rate that exceeds the capacity of the energy storage device, so that the electricity stored in the energy storage device may be less than the total electricity. The vehicle's energy storage device may not even be able to absorb and store the excess current supplied to the DC bus that is not consumed by one or more electrical devices. To compensate for this shortcoming, the control circuit of the motor braking system is configured to control and monitor the current provided to the DC bus from the inverter and the motor and the current consumed by the electrical devices (by performing work) to maintain a balance. This balance can be represented by the voltage of the DC bus remaining within a specified voltage range during the motor braking operation.

[0028] The control circuit can balance the generation and consumption of electricity by first determining the electrical energy consumption capacity (or ability) of one or more electrical devices that consume the generated current. The consumption capacity represents the upper limit of the voltage, current and / or power that one or more electrical devices can consume to operate without causing performance failure, equipment damage or increased risk of overheating. For example, the consumption capacity can represent the power upper limit of the electrical device based on a specified product grade. The power upper limit represents the maximum electrical power that the electrical device is designed to consume. The consumption capacity can be determined by measuring the power consumption characteristics when the corresponding electrical device is operating at full power or full load. Optionally, the consumption capacity can be determined based on device information provided by the manufacturer, and the device information can be entered or uploaded into the memory of the control circuit. If power is to be supplied to multiple electrical devices simultaneously during motor braking, the individual consumption capacities can be aggregated to determine the consumption capacity of the group of electrical devices.

[0029] After determining the consumption capacity, the control circuit controls the inverter and traction motor during motor braking to limit the power generated and supplied to the DC bus to a level that does not exceed the consumption capacity of one or more electrical devices responsible for consuming the power. The control circuit can limit the power generated by the motor by controlling the torque of the motor. The power generated by the traction motor is based on the torque and speed of the rotor. For example, power can be calculated as torque multiplied by speed. The speed can depend on the rotation of the wheels and / or axles. The power can be determined based on the consumption capacity of one or more electrical devices. Based on this equation, the control circuit can calculate the torque level or setting of the motor required to prevent excessive current from being supplied to the DC bus. The control circuit then controls one or more traction motors to operate at this torque level. The torque can be adjusted by controlling the settings and / or characteristics of the inverter and / or motor. For example, the control circuit can change the frequency of the inverter to change the torque of the associated motor. In another example, the control circuit can adjust the phase sequence of the motor or modify the phase connections within the motor.

[0030] In addition to controlling the current supply, the control circuitry also controls the continued operation of the electrical devices throughout the motor braking operation. For example, the control circuitry may operate one or more electrical devices at a specified level (e.g., full power) at the start of motor braking (e.g., traction motor generation) and may maintain the electrical devices operating at the specified level until at least the end of motor braking. Continuously operating the one or more electrical devices ensures that the generated current is consumed without causing a rapid increase in the voltage on the DC bus.

[0031] In an embodiment, a motor-brake system can operate during downhill reverse roll. When the vehicle is about to begin moving, a vehicle on a slope may begin to roll backward after the friction brakes are released. For example, the vehicle may be traveling uphill, but after the brakes are released, the vehicle may begin to roll backward in a downhill direction until traction is provided to propel the vehicle uphill. Rolling back is uncontrolled movement of the vehicle, which is a safety concern. The motor-brake system can utilize motor braking to slow and / or prevent the vehicle from rolling back downhill, thereby reducing the risk of damage or injury caused by rolling back. For example, when the vehicle's wheels rotate while the vehicle is rolling back downhill, the traction motor can generate electricity, and one or more electrical devices can consume the electricity generated by operating during the vehicle's reverse roll. In an embodiment, the control circuit can automatically switch to a motor-brake operating mode during vehicle startup to prepare for reverse roll after the brakes are released. The control circuit can switch to traction mode in response to receiving a control signal directing traction to propel the vehicle.

[0032] The motor brake system can also operate when the vehicle is traveling along a relatively flat road and / or down a downhill slope. Figure 1 The vehicle is traveling along a route in the downhill direction 132 shown. To counteract gravity, which may cause the vehicle to accelerate in the downhill direction, the vehicle may utilize motor braking to decelerate the vehicle and maintain a desired speed. The control circuitry may switch to motor braking mode upon receiving a signal from an operator input device indicating that the vehicle operator has commanded the application of motor braking (e.g., dynamic braking). Alternatively, the control circuitry may automatically switch to motor braking mode based on the grade, current vehicle motion characteristics (e.g., current speed), and specified vehicle motion characteristics. The specified vehicle motion characteristics may be based on operator input (e.g., selecting a specific driving speed), based on a trip plan that specifies a speed along a known route location, etc. The grade may be determined based on sensors on the vehicle (e.g., a tilt sensor) and / or based on a route database and a measured position of the vehicle along the route. For example, the vehicle's position may be determined based on a Global Positioning System (GPS) signal and compared to a route database that includes information on different regions or road segments. The route database may describe the grade of multiple different sections of the route. If the control circuit determines that the vehicle is traveling downhill and the current speed exceeds a specified speed (or a prescribed speed limit), the control circuit can switch to motor braking mode, using the traction motor to slow the vehicle. After the vehicle speed reaches or falls below the specified speed, the control circuit can switch back to traction mode.

[0033] Figure 21 shows a portion of a motor braking system 100 according to an embodiment of the present disclosure. In the illustrated embodiment, the portion of the motor braking system includes a compressor 202. The compressor represents an electrical device that is configured to consume the electricity generated by the traction motor during motor braking operation. More specifically, as Figure 1 As shown, the compressor represents auxiliary electrical equipment 117 that does not generate propulsion. The compressor is electrically connected to the DC bus 110 and powered by the electricity on the DC bus. The compressor performs the work of compressing air. For example, the electricity received from the DC bus can power an internal motor, which converts electrical energy into mechanical energy, rotating a turbine. The rotating turbine draws air into the compressor, compressing it. Due to the work performed, the air leaving the compressor is at a higher pressure than the air entering it.

[0034] The compressor is fluidically connected to the vehicle's air reservoir 204 via a conduit 206. The conduit can be a flexible or rigid length of pipe, hose, etc. The air from the compressor flows through the conduit and enters the air reservoir to load the compressed air into the air reservoir. A flow valve 208 can be mounted on the compressor and / or the conduit. The flow valve selectively opens and closes to control the flow of compressed air from the compressor to the air reservoir. For example, in the open state, compressed air flows from the compressor through the conduit to the air reservoir. In the closed state, no air enters the air reservoir through the conduit. The flow valve can be communicatively connected to the control circuit via a wired or wireless communication route. The control circuit can control the positioning of the flow valve by generating a control signal that is transmitted to the flow valve.

[0035] In an embodiment, the release valve 210 is fluidically connected to the air reservoir and is configured to selectively open the air reservoir to allow compressed air to leave the air reservoir. For example, in the closed position, the release valve covers or blocks an opening or port through the wall of the air reservoir. The position of the release valve between the open state and the closed state can be controlled by a control circuit. The release valve can be a piston-type solenoid valve or other type of valve. Alternatively, for safety purposes, the release valve can be configured to automatically open in response to the pressure in the air reservoir exceeding a specified upper limit, regardless of a control signal from the control circuit.

[0036] Before operating in motor braking mode, the control circuitry first determines the power consumption capacity of one or more electrical devices responsible for consuming the power generated during motor braking mode. In the illustrated embodiment, where the one or more electrical devices include a compressor, the control circuitry can measure or calculate the rate or amount of power consumed by the compressor when operating at a specified setting. The specified setting can be a full power setting or full load. The power consumption of the compressor at full power represents an upper limit on the power the compressor can consume. This consumption can be measured using one or more sensors that generate signals indicating the rate or amount of current drawn by the compressor. Alternatively, the compressor can be the sole electrical device used to consume the power generated by the one or more motors during motor braking. Alternatively, the compressor can be used in conjunction with other electrical devices, such as another compressor, another type of auxiliary electrical device, or even a traction motor, to consume the power generated during motor braking. As described above, after determining the total power consumption capacity of the one or more electrical devices, the control circuitry can adjust the inverter and / or traction motor when switching to motor braking mode to balance the amount or rate of power generated by the motors with the amount or rate of current consumed by the one or more electrical devices.

[0037] In one embodiment, upon switching to motor braking mode, the control circuit automatically controls the compressor to operate at a specified setting (e.g., a full power setting). For example, if the compressor is already operating at a different setting, the control circuit may send a control signal commanding the full power setting. If the compressor is in an off state, the control circuit turns the compressor on to the full power setting. If the compressor is already operating at the full power setting, the control signal maintains the compressor operating at that setting, such as by preventing or blocking the transmission of a signal commanding the compressor to deviate from the full power setting. The compressor may be controlled to operate at the full power setting throughout the motor braking operation. The control circuit may utilize a valve to ensure that the compressor can maintain operation at the full power setting for an extended period of time.

[0038] Figure 3 Graph 300 illustrates pressure in a vehicle air reservoir over time, according to an embodiment of the present disclosure. A control circuit controls a valve to maintain the air pressure in the air reservoir within a specified range 302. The specified range may represent the air pressure necessary to ensure certain functions, such as successful air braking of a vehicle. If the air pressure drops below a lower limit 304 of the range, the air reservoir may not have sufficient air pressure to perform certain functions. If the air pressure exceeds an upper limit 306 of the range, the high pressure may cause damage to the air reservoir, the valve, and / or other components connected to and / or in close proximity to the air reservoir.

[0039] In the graph, time t1 represents the time when the vehicle enters the motor braking mode. As shown by the plotted line 308, before time t1, the pressure in the air reservoir is a constant amount within a specified range. At time t1, the control circuit opens the flow valve 208 (as shown in FIG. Figure 2 The control circuit also controls the compressor to operate at a full power setting (or other specified setting where the consumed capacity of the compressor is known). The compressor remains at the full power setting throughout the motor braking operation, which extends to time t5 in the graph.

[0040] When the compressor is running during the motor braking operation, the air compressed by the compressor flows through the pipeline to the air reservoir, and the air pressure of the air reservoir gradually increases from time t1 to time t2. At time t2, the pressure of the air reservoir exceeds the upper limit of the specified range. The control circuit can monitor the pressure in the air reservoir based on the sensor signal received from the pressure sensor in the air reservoir. In response to determining that the pressure is greater than the specified range, the control circuit generates a control signal to open the release valve 210 (such as Figure 2 (as shown). The release valve opens to release some compressed air from the air reservoir, while the compressor continues to be powered by electricity from the DC bus. For example, from time t2 to time t3, both the compressor flow valve and the release valve are open. The compressor supplies compressed air to the air reservoir, and the release valve simultaneously releases compressed air from the air reservoir. In one embodiment, the amount or rate of compressed air flowing out of the air reservoir through the release valve exceeds the amount or rate of compressed air entering the air reservoir when the compressor is operating at full power, thereby gradually decreasing the air pressure in the air reservoir to maintain the air pressure in the air reservoir within a specified range. The rate of decrease in air pressure from time t2 to time t3 can be different from the rate of increase in pressure from time t1 to time t2. In the illustrated embodiment, the pressure drop when the release valve is open is slower (e.g., more gradual) than the pressure rise when the release valve is closed. At time t3, the pressure in the air reservoir drops below the lower limit of the specified range, so the control circuit closes the release valve. The pressure in the air reservoir increases again until the control circuit opens the release valve again at time t4.

[0041] As shown in the diagram, the control circuit can continuously cycle the release valve between opening and closing to maintain the air pressure within a specified range while the compressor continues to operate at its full power setting. In the graph, motor braking mode ends at time t5, at which point the control circuit can close the compressor flow valve and / or shut down or modify the compressor's operation. After time t5, the air pressure in the air reservoir is constant.

[0042] During motor braking, the one or more electrical devices controlled to consume the power generated by the traction motor are not limited to Figure 2The compressor shown. Another example of an electrical device is a lighting system, including one or more vehicle lights. The vehicle lights may include headlights, taillights, interior lights, etc. When switching to motor braking mode, the control circuit can turn on the lights in the lighting system. These lights can consume relatively stable power from the DC bus. Another example of an electrical device that can be used to consume generated power by performing work includes fans and blowers.

[0043] Another example of an electrical device is a heating, ventilation and air conditioning (HVAC) system on a vehicle, such as a cooling device and / or a heating device. The cooling device may include an air conditioner. The heating device may include a heater or a space heater. In an embodiment, when switching to the motor braking mode, the control circuit may turn on the HVAC system. Figure 2 Like the valves shown, during motor braking mode, the control circuitry can control air handling devices (e.g., shutters) to maintain the temperature within the vehicle, engine compartment, and / or the like within a specified temperature range, regardless of continued operation of the HVAC system. For example, the control circuitry can operate the air conditioner at full power. Once the temperature within the vehicle falls below the lower limit of the specified temperature range, the control circuitry can adjust the shutters to close the register that discharges cooled air into the vehicle cabin and direct the cooled air into the engine compartment or the surrounding environment. Once the temperature within the vehicle cabin exceeds the upper limit of the specified temperature range, the control circuitry can again adjust the shutters to open the register.

[0044] Yet another example of an electrical device is a traction motor of a vehicle. Figure 1 As described above, during motor braking mode, the control circuitry can control a first subset of traction motors on the vehicle to operate as generators, and a second subset of traction motors on the vehicle to consume power from the DC bus by generating propulsion as the work performed. In this scenario, some traction motors brake the vehicle while other traction motors apply torque to propel the vehicle, which can be useful in certain situations, such as when the vehicle is reversing downhill. When the vehicle is reversing downhill in a direction opposite to the intended direction of travel, the first subset of traction motors performs motor braking to convert the vehicle's kinetic energy into electrical energy, which slows the vehicle's reversing due to the mechanical resistance of the motors and linkage. The second subset of traction motors can consume power from the DC bus, either alone or in conjunction with one or more auxiliary electrical devices, to maintain the DC bus within a specified voltage range. The second subset of traction motors consumes current to generate torque, which is applied to the wheels and / or axles via the linkage to propel the vehicle in the intended direction of travel (e.g., opposite to the reverse direction).

[0045] The control circuit can optionally operate multiple different types of electrical devices simultaneously to consume the power generated by one or more traction motors. For example, the control circuit can operate compressors connected in series (such as Figure 2 Utilizing multiple electrical devices may result in an increase in consumption capacity, which can relieve stress on the inverter and motor by allowing them to supply more current to the DC bus.

[0046] Figure 4 400 is a flow chart of a method for performing vehicle motor braking according to an embodiment of the present disclosure. Figures 1 to 3 Certain steps of the method may be performed by Figure 1 The control circuitry shown executes according to programmed logic or instructions. The method may optionally include more steps than shown, fewer steps than shown, and / or different steps than shown. By performing the method, electrical power generated by one or more vehicle traction motors based on vehicle movement can be consumed during vehicle movement (concurrently with power generation) without dissipating the current as heat through a resistor array or grid.

[0047] In step 402, the power consumption capacity of one or more electrical devices on the vehicle during reverse downhill travel is determined. Capacity represents the amount or rate at which electrical energy can be consumed by the electrical devices while the vehicle is in reverse. In step 404, electrical power is generated by the vehicle while it is in reverse downhill travel. This power can be generated by one or more traction motors of the vehicle operating as generators to convert the vehicle's kinetic energy during reverse travel into electrical energy. The generated power is limited to a level that does not exceed the power consumption capacity of the electrical devices to operate during reverse travel (e.g., not simply dissipating current as heat using resistors).

[0048] In step 406, the electricity generated during the vehicle's reverse operation is consumed by one or more electrical devices utilizing the electricity to perform work. Optionally, in step 408, consuming the electricity during reverse operation may include powering one or more auxiliary electrical devices of the vehicle that do not generate propulsion (e.g., a compressor, a blower, a fan, an HVAC system, a lighting system, an electronic system, etc.). Optionally, in step 410, consuming the electricity during reverse operation may include powering one or more traction motors of the vehicle to (i) prevent the vehicle from rolling downhill and / or (ii) propel the vehicle uphill by generating propulsion as the work performed.

[0049] Figure 5 500 is a flow chart of a method for consuming power according to an embodiment of the present disclosure. Figure 4is implemented in the motor braking method of the vehicle. For example, flowchart 500 can represent the power consumption step 408 of method 400. In an embodiment, the vehicle has one or more auxiliary electrical devices that do not generate propulsion, including a compressor connected to an air reservoir. In step 502, the compressor is powered by the electricity generated during the reverse process and performs the work of compressing air. In step 504, the air reservoir of the vehicle is loaded with compressed air from the compressor. In step 506, it is determined whether the air pressure of the air reservoir is greater than a specified pressure range representing an acceptable pressure. If the pressure exceeds the pressure range, then step 508 is performed, and the automatic control valve (such as a release valve) is opened to release part of the compressed air from the air reservoir, while the compressor continues to perform the work of air compression. Optionally, when the valve is opened to release the compressed air in the air reservoir, the compressed air from the compressor continues to be supplied to the air reservoir.

[0050] After opening the valve or determining that the pressure in the air reservoir does not exceed the specified range, the process proceeds to step 510 to determine whether the air pressure in the air reservoir is less than the specified pressure range. If the air pressure in the air reservoir is less than the specified pressure range, the valve automatically closes, gradually increasing the pressure in the air reservoir while the compressor continues to supply compressed air. After closing the valve or determining that the pressure does not fall below the specified range, the process returns to step 504. It should be noted that the loading of the air reservoir in step 504 can occur continuously through the feedback control operations described in steps 506, 508, 510, and 512.

[0051] One or more technical effects of the vehicle motor-brake system described herein include the ability to perform motor-based braking of a vehicle without the need for, or even the presence of, a dynamic brake grid comprised of resistors to dissipate excess motor-generated electricity as heat. One or more technical effects may also include the ability to perform motor-based braking of a vehicle without the need for, or even the presence of, an energy storage device for storing motor-generated electricity for future use. By not relying on a dynamic brake grid and / or an energy storage device, the motor-brake system reduces the components required to provide motor braking, which enables motor braking to be implemented on a wider range of vehicles.

[0052] In an embodiment, a system (e.g., a vehicle braking system) includes one or more traction motors and an electrical device configured to be electrically connected to the one or more traction motors. The one or more traction motors are configured to propel the vehicle and generate electricity during reverse downhill movement of the vehicle. The electrical device is configured to consume electricity generated by the reverse movement of the vehicle by performing work using the electricity during reverse movement of the vehicle.

[0053] Optionally, the vehicle does not include a dynamic braking grid in which the electrical power is dissipated as heat. Optionally, the electrical equipment is an auxiliary electrical equipment that does not generate propulsion. The auxiliary electrical equipment that does not generate propulsion can be configured to consume electrical power at a rate not exceeding a power cap, and the one or more traction motors are controlled to limit the electrical power generated during reverse to no more than the power cap.

[0054] Optionally, the electrical device includes a compressor configured to be powered by electricity to compress air. The compressor can be configured to be powered by electricity to compress air to charge an air reservoir of the vehicle. The system can also include a valve fluidically connected to the air reservoir of the vehicle. The valve is configured to release some of the air compressed by the compressor in the air reservoir while the compressor is powered by electricity, thereby maintaining the air pressure in the air reservoir within a specified range.

[0055] Optionally, the electrical device includes one or more traction motors powered by electricity to perform one or more of the following: (i) preventing the vehicle from rolling back down a hill; (ii) propelling the vehicle up a hill by generating propulsion force as the work performed.

[0056] In an embodiment, a method (eg, for vehicle braking) includes generating electricity from reversing a vehicle downhill. The method also includes consuming the electricity generated by reversing the vehicle by performing work with the electricity during the reversing of the vehicle.

[0057] Optionally, the electrical power is consumed by powering one or more auxiliary electrical devices of the vehicle that do not generate propulsion. Substantially all of the electrical power generated by the vehicle in reverse can be consumed by powering one or more auxiliary electrical devices that do not generate propulsion. The one or more auxiliary electrical devices of the vehicle that do not generate propulsion can be configured to consume electrical power at a rate no greater than a power cap. Generating electrical power can include limiting the electrical power generated during reverse so that it does not exceed the power cap.

[0058] Optionally, the electricity is consumed by powering a compressor of the vehicle, thereby utilizing electricity to compress the air. The method may further include charging an air reservoir of the vehicle with air compressed by the compressor powered by the electricity. The method may further include opening a valve to release a portion of the air compressed by the compressor in the air reservoir while the compressor is powered by the electricity, thereby maintaining the air pressure in the air reservoir within a specified range.

[0059] Optionally, the electrical power is consumed by powering one or more traction motors of the vehicle to perform one or more of the following: (i) preventing the vehicle from rolling down a hill; or (ii) propelling the vehicle up a hill by generating propulsion as the work performed. Optionally, one or more of the amount or rate of electrical power generation may exceed the capacity of the vehicle's energy storage device, thereby causing less than the full amount of electrical power to be stored in the energy storage device. Optionally, the vehicle does not include a dynamic brake grid, in which electrical power is dissipated as heat.

[0060] In an embodiment, an electric vehicle is provided that includes a traction motor and a load. The traction motor is configured to generate electricity through regenerative braking during downhill travel of the electric vehicle. The load is incapable of storing the generated electricity. The load is configured to receive electricity and operate using the electricity generated by the regenerative braking during downhill travel of the electric vehicle.

[0061] Optionally, the load comprises a compressor configured to perform air compression as its work performed using electricity. Optionally, the traction motor is a first traction motor, and the load comprises a second traction motor configured to generate torque to enable the electric vehicle to climb a slope using electricity.

[0062] As used herein, the terms "processor" and "computer" and related terms such as "processing device," "computing device," and "controller" may not be limited to those integrated circuits known in the art as computers, but may refer to microcontrollers, microcomputers, programmable logic controllers (PLCs), field programmable gate arrays, application specific integrated circuits, and other programmable circuits. Suitable memory may include, for example, computer-readable media. Computer-readable media may be, for example, random access memory (RAM), computer-readable non-volatile media, such as flash memory. The term "non-transitory computer-readable medium" represents a tangible computer-based device for short-term and long-term storage of information, such as computer-readable instructions, data structures, program modules and submodules, or other data in any device. Therefore, the methods described herein may be encoded as executable instructions contained in a tangible, non-transitory computer-readable medium, which includes, but is not limited to, storage devices and / or memory devices. Such instructions, when executed by a processor, cause the processor to perform at least a portion of the methods described herein. Thus, the term includes tangible computer-readable media, including but not limited to non-transitory computer storage devices, including but not limited to volatile and non-volatile media, and removable and non-removable media such as solid-state, physical and virtual storage, CD-ROMs, DVDs and other digital resources, such as a network or the Internet.

[0063] Unless the context clearly dictates otherwise, the singular forms "a", "an" and "the" include plural references. "Optional" or "optionally" means that the event or circumstance subsequently described may or may not occur, and the description may include instances where the event occurs and instances where it does not occur. Approximate expressions used throughout the specification and claims may be used to modify any quantitative representation that is permitted to vary without resulting in a change in the basic function to which it is associated. Therefore, a value modified by one or more terms (such as "about", "substantially" and "approximately") may not be limited to the precise value specified. At least in some cases, an approximate expression may correspond to the precision of an instrument for measuring a value. Here and throughout the specification and claims, range limitations may be combined and / or interchanged, and unless the context or expression indicates otherwise, such ranges may be identified and include all subranges contained therein.

[0064] This written description uses examples to disclose the embodiments, including the best mode, and to enable any person skilled in the art to practice the embodiments, including making and using any devices or systems and performing any incorporated methods. The claims define the patentable scope of the disclosure and include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

1. A vehicle braking system, characterized in that: The system comprises: one or more traction motors configured to propel the vehicle and to generate electricity during reverse downhill travel of the vehicle; and a compressor configured to be electrically connected to the one or more traction motors and in fluid connection with an air reservoir of the vehicle and configured to consume the electricity generated by the one or more traction motors during reverse movement of the vehicle by generating a supply of compressed air to the air reservoir, The compressor is configured to continuously operate to generate the compressed air throughout the period in which the one or more traction motors generate electricity in response to detecting the reverse roll.

2. The system according to claim 1, wherein: The vehicle does not include a dynamic brake grid in which the electrical power is dissipated as heat.

3. The system according to claim 1, wherein: The system further comprises: One or more processors are communicatively coupled to the one or more traction motors, the one or more processors being configured to limit the electrical power generated by the one or more traction motors during the reverse phase to not exceed a power cap associated with an electrical energy consumption capacity of the compressor.

4. The system according to claim 1, wherein: The system further comprises: A valve is fluidically connected to the air tank of the vehicle, and the valve is configured to release a portion of the compressed air from the air tank during the process of the compressor being powered by the electricity to maintain the air pressure of the air tank within a specified range.

5. The system according to claim 1, wherein: The one or more traction motors that generate the electricity during the reverse motion are represented as a first group of traction motors, and the system further includes one or more traction motors represented as a second group of traction motors, which are powered by the electricity generated by the first group of traction motors to provide torque to achieve one or more of the following: (i) prevent the vehicle from reverse downhill; (ii) propel the vehicle uphill.

6. The system according to claim 1, wherein: The compressor is configured to operate at a full power setting throughout the time that the one or more traction motors are generating electricity in response to detecting the reverse roll.

7. The system according to claim 1, wherein: The air reservoir is a component of the vehicle's braking system.

8. The system according to claim 4, wherein: The system further includes one or more processors in communication with the valve, the one or more processors being configured to open the valve when the gas pressure in the gas cylinder exceeds an upper limit of the specified range, and to close the valve when the gas pressure in the gas cylinder is below a lower limit of the specified range.

9. A vehicle braking method, characterized in that: The method comprises: generating electricity by one or more traction motors of a vehicle during reverse downhill travel of the vehicle, the one or more traction motors being configured to propel the vehicle; and controlling a compressor to consume the electricity generated by the reverse movement of the vehicle by generating compressed air; supplying the compressed air generated during the reverse movement of the vehicle to an air tank to charge the air tank, Controlling the compressor to consume the electricity by generating the compressed air includes controlling the compressor to continuously operate to generate the compressed air during the entire process in which the one or more traction motors generate the electricity during the reverse operation.

10. The method according to claim 9, characterized in that Controlling the compressor includes controlling the compressor to consume substantially all of the power generated by the one or more traction motors during reverse downhill rolling of the vehicle.

11. The method according to claim 9, characterized in that Generating the electrical power includes limiting the electrical power generated by the one or more traction motors during the reverse phase to not exceed a power cap associated with an electrical energy consumption capacity of the compressor.

12. The method according to claim 9, characterized in that The method further comprises: In the process of controlling the compressor to generate the compressed air and supplying the compressed air to the air reservoir, a valve is opened to release part of the compressed air from the air reservoir, thereby maintaining the air pressure of the air reservoir within a specified range.

13. The method according to claim 9, characterized in that Describing the one or more traction motors generating the electric power during the reverse as a first group of traction motors, the method further comprises: powering one or more traction motors, represented by a second set of traction motors, of the vehicle during the reverse motion with electricity generated by the first set of traction motors; The second group of traction motors is controlled to provide torque to achieve one or more of the following: (i) preventing the vehicle from rolling downhill; (ii) propelling the vehicle uphill.

14. The method according to claim 9, characterized in that Generating the electricity during the reverse by one or more traction motors of the vehicle includes generating the electricity in one or more of an amount or a rate that exceeds the capacity of an energy storage device of the vehicle, thereby resulting in less than all of the electricity stored in the energy storage device.

15. A vehicle braking system, characterized in that: The system comprises: a plurality of traction motors configured to be disposed on the vehicle and to propel the vehicle; and One or more processors configured to control a first group of traction motors among the plurality of traction motors to generate electricity by regenerative braking during a downhill reverse roll of the vehicle, and to control a second group of traction motors among the plurality of traction motors to provide torque using at least a portion of the electricity generated by the first group of traction motors during the reverse roll, to achieve one or more of the following: (i) preventing the vehicle from rolling downhill; and (ii) propelling the vehicle uphill.

16. The system according to claim 15, wherein: The system further includes a compressor fluidly connected to an air tank of the vehicle, The one or more processors are configured to power the compressor with a portion of the electricity generated by the first set of traction motors during the reverse phase to produce a compressed air supply to the air reservoir.

17. The system according to claim 16, wherein: The one or more processors are configured to control the compressor to continuously operate to generate the compressed air throughout the time that the first set of traction motors is generating the electricity during the reverse operation.

18. The system according to claim 17, wherein: The air reservoir includes a release valve configured to release a portion of the compressed air from the air reservoir according to the air pressure within the air reservoir, while the compressor continues to generate compressed air supplied to the air reservoir during the reverse operation.

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