Power management system for a transport refrigeration unit

Abstract

A vehicle for transporting cargo, a tractor-trailer system for transporting cargo, and a method of operating a power management system for providing power to a transport refrigeration unit are described. The vehicle for transporting cargo includes: an axle; a transport refrigeration unit; and a power management system for supplying power to the transport refrigeration unit. The power management system includes: a generator configured to selectively couple to the axle of the vehicle, wherein the generator is configured to generate electrical power when coupled to the axle; and a controller configured to monitor a speed of the vehicle and selectively couple and decouple the generator from the axle. The controller is configured to determine that the vehicle is in a first state and decouple the generator from the axle when the vehicle is in the first state, wherein the speed of the vehicle is increasing in the first state. The controller is configured to determine that the vehicle is in a second state and couple the generator to the axle when the vehicle is in the second state, wherein the speed of the vehicle is substantially constant in the second state.

Description

Technical Field

[0001] The present invention relates to a vehicle for transporting goods, a tractor-trailer system for transporting goods, and a method for operating a power management system for providing power to a transport refrigeration unit. Background Technology

[0002] Transport refrigerated units (TRUs) are used within logistics networks to transport perishable or temperature-sensitive goods and consumables. TRUs typically regulate the monitored environment within storage areas (such as containers or trailers) where goods are stored during transport. This monitored environment is regulated using refrigeration systems, which are in turn powered by an energy source. Traditionally, the energy source for such refrigeration systems is an internal combustion engine.

[0003] TRUs are implemented or integrated into storage containers, trailers, etc. The trailers or containers are then coupled to or loaded onto trucks / tractors, trains, or other vehicles that transport the goods to their intended destination. The driving vehicles are typically powered by a separate internal combustion engine.

[0004] The transportation of goods, such as those used in the food industry, has historically relied on fossil fuels and other non-renewable energy sources. These sources power not only the vehicles transporting the goods but also the equipment used to regulate their storage. Therefore, non-renewable fuels represent a significant expense within industry. Non-renewable fuels, such as petroleum and diesel, also contribute to environmental damage. There is an expectation within industry to reduce fuel consumption.

[0005] In recent years, this has been partially achieved by implementing electric power sources to power TRUs instead of internal combustion engines. Such power sources can be charged using electricity from the power grid and can also be recharged via energy harvesting devices such as solar panels and generators. The use of electric power sources and energy harvesting devices to power TRUs has reduced fossil fuel consumption within industry. However, further optimization and / or reduction of fuel consumption during cargo transportation remains necessary. Summary of the Invention

[0006] According to a first aspect of the invention, a vehicle for transporting goods is provided, the vehicle comprising: an axle; a transport refrigeration unit; and a power management system for supplying power to the transport refrigeration unit; wherein the power management system comprises: a generator configured to be selectively connected to the axle of the vehicle, wherein the generator is configured to generate electricity when connected to the axle; and a controller configured to monitor the speed of the vehicle and selectively connect and disconnect the generator from the axle; wherein the controller is configured to determine that the vehicle is in a first state, and disconnect the generator from the axle when the vehicle is in the first state, wherein the speed of the vehicle is increasing in the first state; and wherein the controller is configured to determine that the vehicle is in a second state and connect the generator to the axle, wherein the speed of the vehicle is substantially constant in the second state.

[0007] The generator is configured to generate electricity when connected to the axle. Therefore, the power management system can utilize the generator to provide power or regenerate power via the rotation of the axle. In other words, when connected to the axle, the generator is driven by the axle. Thus, the transport refrigeration unit can be powered by the electricity generated from the generator, thereby reducing or eliminating the transport refrigeration unit's dependence on non-renewable / fossil fuels.

[0008] As stated above, when connected to an axle, the generator can be driven by the axle to generate electricity. However, connecting the generator to the axle increases the torque required to turn the axle, and the vehicle experiences a greater load due to the torque exerted by the generator on the axle. Therefore, engine torque will be needed to accelerate the vehicle or maintain a constant speed. Providing torque requires more energy, which in turn leads to greater consumption of fuel or energy to drive the vehicle. During acceleration, engine fuel efficiency typically decreases, meaning that operating the generator at this time also reduces the effective fuel efficiency of the generator's power generation.

[0009] By monitoring whether the vehicle's speed is increasing, the power management system can selectively connect or disconnect the generator from the axles. When the vehicle's speed is substantially constant (i.e., the vehicle is not accelerating or decelerating), the vehicle can be in a state suitable for generating electricity (e.g., to power the TRU). However, when the rate of change of the vehicle's speed is increasing, the generator can be disconnected from the axles, resulting in a reduction in the torque acting on the axles (and therefore the engine). The force required to turn the axles is reduced, and therefore fuel consumption during vehicle acceleration is reduced. As a result, fuel is consumed more efficiently when driving a vehicle that includes a generator connected to the axles.

[0010] A generator can also be called a wheel-axle generator because it generates electricity by rotating a wheel or axle when connected. Generators can be induction generators.

[0011] The axle can be a passive axle, meaning it can rotate due to the contact force between the wheel connected to the axle and the drive surface. Therefore, electrical energy can be harvested from the vehicle's motion via the rotation of the wheels.

[0012] The vehicle can be a passive vehicle, such as a trailer or truck, meaning it does not include a motor or engine for driving the vehicle. The vehicle itself may not be able to provide driving force / prime power. Alternatively, the passive vehicle can be driven by a corresponding driving vehicle, such as a truck or train, which provides driving force / prime power to the vehicle. Thus, the axles can be indirectly driven by driving force provided by the driving vehicle (e.g., through contact forces with the road surface, rails, or other suitable driving surfaces).

[0013] The vehicle can be an active vehicle, such as a box truck or van. That is, the vehicle may include an engine that provides driving force / prime power to the vehicle. Additionally, the vehicle may include a storage area where the TRU is located and where cargo can be stored. Therefore, the vehicle itself may be able to provide driving force / prime power, rather than a vehicle towed by a driving vehicle. The vehicle may include active and passive axles, with driving force delivered through the active axle and the passive axles indirectly driven by driving force (e.g., through contact force with a road surface, rail, or other suitable driving surface). A generator may be selectively coupled to the passive axles. In such a system, the power management system can operate largely independently of the vehicle's engine.

[0014] Vehicles may include passive and active vehicles. Passive vehicles may be driven by active vehicles. For example, a vehicle may be a tractor-trailer system. Axles may be axles of a tractor. Axles may be axles of a trailer. A TRU may be housed within a trailer.

[0015] The generator can be configured to provide power to the transport refrigeration unit. In other words, when connected to the axle, the electricity generated by the generator can be directly supplied to the transport refrigeration unit.

[0016] The power management system may include an energy storage device. The energy storage device may be operable to provide power to the transport refrigeration unit. The energy storage device may be configured to store electrical energy. The energy storage device may be a rechargeable battery, capacitor, etc. The energy storage device may be charged by a generator. The energy storage device may supply power to the TRU. When the vehicle is stationary, the energy storage device may be charged via the power grid.

[0017] The controller can be configured to determine the power requirements of the transport refrigeration unit. The controller can also be configured to determine the generator's power generation rate, i.e., the rate at which electricity is generated when the generator is connected to the axle. If the power generation rate exceeds the power requirements, the controller can be configured to use the generator to recharge the energy storage device and provide power to the transport refrigeration unit. If the power requirements exceed the power generation rate, the controller can be configured to provide power to the transport refrigeration unit simultaneously via the generator and the energy storage device.

[0018] The energy storage device can be selectively recharged by a generator. That is, the generator can recharge the energy storage device when its state of charge falls below a predetermined threshold. This threshold can be at least 80% of the energy storage device's capacity, and optionally at least 90%. Alternatively, the generator can recharge the energy storage device when it generates surplus power. That is, when the generator's power generation rate exceeds the power requirements of the TRU, the surplus power generated by the generator can be used to recharge the energy storage device. This is possible, for example, at high vehicle speeds. Therefore, the power generated by the generator is efficiently collected, allowing the TRU to be operated with regenerated power where possible. This increases the vehicle's travel time between destinations when recharging the energy storage device is not required. It also increases the vehicle's fuel efficiency because energy is collected more efficiently by the generator, and the generator can be disconnected from the axles when appropriate.

[0019] Energy storage devices and generators can simultaneously power the TRU. For example, if the TRU's power demand exceeds the rate at which the generator produces electricity when connected to the axle, the energy storage device can supplement the power supplied by the generator. This is possible, for example, at low vehicle speeds. Therefore, the TRU can be powered by a generator and energy storage device connected in series, ensuring that the TRU's power demand is always met. Furthermore, by using a generator connected in series with the energy storage device to power the TRU, the energy storage device can release energy at a slower rate than if the TRU were powered solely by the energy storage device. In other words, by prioritizing the use of regenerative electricity to power the TRU, the lifespan between charges where the power management system can provide sufficient power to the TRU is increased.

[0020] If the generator is disconnected from the axle and therefore no electricity is generated by the generator, the TRU can be powered solely by the energy storage device. Therefore, the generator does not always need to be connected to the axle and can be disconnected when necessary while still providing sufficient power to the TRU. This is possible, for example, when the vehicle is accelerating or stationary. Thus, sufficient power can be provided to the TRU at all times, and fuel consumption can be reduced during vehicle acceleration.

[0021] When a generator is connected to the axle, the TRU can also be powered solely by the generator. For example, if the generator's generation rate meets the TRU's power requirements, the generator can directly supply power to the TRU.

[0022] When the rate of change of the vehicle's speed is greater than at least 0.1 m / s 2 At least 0.2 m / s 2 At least 0.3 m / s 2 At least 0.4 m / s 2 At least 0.5 m / s 2 At this time, it can be determined that the rate of change of the vehicle's speed is increasing and / or decreasing. For example, when the magnitude of the rate of change of the vehicle's speed is no greater than 0.1 m / s². 2 At most 0.2 m / s 2 At most 0.3 m / s 2 At most 0.4 m / s 2 Or at most 0.5 m / s 2 If the rate of change of vehicle speed is essentially zero, then the vehicle speed can be considered constant. Alternatively, if the fluctuation within a predetermined time period is within a certain tolerance, the vehicle speed can be considered essentially constant. The time period can be less than 1 minute, less than 30 seconds, or less than 10 seconds. The fluctuation tolerance can be a percentage range of vehicle speed, where the percentage value can be less than 1%, less than 2%, less than 3%, less than 4%, or less than 5%. Alternatively, the fluctuation tolerance can be a numerical range, where the tolerance can span a range less than 1 m / s, less than 2 m / s, less than 3 m / s, less than 4 m / s, or less than 5 m / s.

[0023] By determining that a vehicle is accelerating only when its acceleration exceeds a set threshold, small fluctuations in vehicle speed caused by the driver's accelerator pedal control can be ignored, and the ride is smoother because the vehicle does not rapidly connect and disconnect the generator from the axle.

[0024] The controller can be configured to monitor and / or determine the state of charge of the energy storage device.

[0025] When the state of charge exceeds a first threshold, the vehicle can disconnect the generator from the axle. The vehicle can remain disconnected from the axle until the state of charge of the energy storage device is below a second threshold. The first threshold is greater than the second threshold.

[0026] The controller can be configured to determine that the vehicle is in a third state, and to connect the generator to the axle when the vehicle is in the third state, wherein the state of charge of the energy storage device is below a first threshold. In the third state, the vehicle speed can be constant, or the vehicle speed can be increasing. That is, the vehicle can be in a state where the controller is configured to connect the generator to the axle when the state of charge of the energy storage device is less than an operating threshold.

[0027] If the state of charge of the energy storage device is above a first threshold, the excess power generated by the generator can be delivered to other components of the vehicle or other components within the power management system. Alternatively, if the generation rate exceeds the power requirements of the TRU, the generator can be disconnected from the axle, and the TRU can be powered by the energy storage device until the energy storage device has released sufficient energy to be recharged by the generator.

[0028] Therefore, under certain conditions, even when the vehicle is not accelerating, the generator can be disconnected from the axle, thus reducing fuel consumption. Once the state of charge has decreased until it falls below a lower second threshold, the generator can be reconnected to the axle if necessary conditions are met, such as if the vehicle speed is substantially constant, to maintain a sufficient state of charge for the energy storage device. The first threshold may be at least 5%, at least 10%, at least 15%, at least 20%, or at least 25% greater than the second threshold.

[0029] As stated above, if the state of charge of the energy storage device is below the operating threshold, the controller can be configured to connect the generator to the axle. When the state of charge of the energy storage device is below the operating threshold, the vehicle can remain in a third state even while accelerating.

[0030] The first threshold can be considered as the minimum acceptable state of charge (SOC) of the energy storage device, ensuring that the transport refrigeration unit can be powered for a minimum acceptable amount of time. The first threshold can be at least 5%, at least 10%, at least 15%, or at least 20% of the energy storage device's capacity. The operational threshold can be less than 75%, less than 50%, or less than 25% of the energy storage device's capacity. The operational threshold can correspond to the predicted operational life of the TRU. For example, the threshold can be at least 30 minutes, at least 1 hour, at least 2 hours, or at least 3 hours. By connecting a generator to the axle when the SOC is below the first threshold, recharging the energy storage device using the generator can be prioritized over optimizing fuel consumption when driving the vehicle. This helps prevent damage to the cargo being transported and ensures that the TRU is provided with sufficient power during vehicle transport.

[0031] The controller can be configured to determine the rate of change of the vehicle's speed. The controller can also be configured to determine whether the vehicle is in a fourth state, and when the vehicle is in the fourth state, to connect the generator to the axles. In the fourth state, the rate of change of the vehicle's speed may be decreasing. There are some cases where deceleration (i.e., the vehicle's speed is decreasing) can be a result of driver intervention. In these cases, it is desirable to regenerate energy that would otherwise be lost.

[0032] The controller can be configured to determine whether the vehicle is braking. The vehicle can be braking in a fourth state. The vehicle can be in a state where it is braking, in which the controller is configured to connect a generator to the axles. In this way, energy that would otherwise be lost during braking can be converted into electricity using the generator.

[0033] The vehicle may include one or more sensors for determining the vehicle's speed and / or rate of change of speed. The one or more sensors may be, for example, wheel speed sensors or accelerometers.

[0034] The vehicle may include a location determination device such as a GPS device. The location determination device may be configured to relay real-time location data to the controller. In this context, real-time location information is intended to mean that the location is the vehicle's current location, such as within the last 5 seconds, the last 1 second, or the last 0.5 seconds. The controller may be able to determine the rate of change of the vehicle's speed based on the real-time location data. For example, when transmitted in real time, the location data will allow the controller to determine the change of the vehicle's position relative to time, thus enabling the determination of the rate of change of the vehicle's speed. Therefore, it may be determined whether the generator should be connected to the axle depending on the state of the vehicle.

[0035] By providing the vehicle with a position determination device, the power management system can determine the rate of change of the vehicle's speed. Furthermore, the power management system can determine the rate of change of the vehicle's speed without utilizing readings from any sensors that are not part of the power management system and / or the vehicle itself. For example, if the vehicle is a trailer in a tractor-trailer system, the system operating the tractor and thus driving / accelerating the tractor and trailer does not necessarily need to communicate with the trailer. The power management system can determine whether the trailer is changing speed independently of the tractor. Therefore, in large fleets, vehicles of the first aspect can be more easily integrated because no additional communication protocol or connection between the tractor and trailer is required. Alternatively, existing vehicles can be more easily retrofitted using a power management system according to the first aspect because a connection between the engine management system and the power management system is unnecessary for the controller to determine the rate of change of the vehicle's speed.

[0036] The controller can be configured to determine whether the vehicle's speed is decreasing. The controller can be configured to determine that the vehicle is in a fourth state, and when the vehicle is in the fourth state, to connect a generator to the axles. In the fourth state, the vehicle's speed may be decreasing. The controller can also be configured to determine whether the vehicle is braking, for example, based on real-time position data or other data received by the controller. The vehicle may be braking in the fourth state. Therefore, if the vehicle is decelerating, for example, due to braking, the controller can be configured to connect a generator to the axles.

[0037] However, if the vehicle is not decelerating due to braking, it is desirable not to connect the generator to the axles. For example, the controller can be configured to determine that the vehicle is in a fifth state, and connect the generator to the axles when the vehicle is in the fifth state. In the fifth state, the vehicle speed may be decreasing, but the vehicle may not be braking.

[0038] The controller can be configured to determine whether the vehicle is traveling uphill, downhill, or on a flat surface based on real-time location data. The controller can also be configured to determine the vehicle's additional state and disconnect the generator from the axle when the vehicle is in an additional state. When the vehicle is in an additional state, its speed is decreasing, and it is traveling on an uphill surface. That is, the controller can determine that the vehicle is in an additional state when it is not decelerating due to braking. If the vehicle's speed is decreasing and it is traveling on a flat or downhill surface, or if the vehicle's speed is substantially constant and it is traveling on a downhill surface, the controller can determine that the vehicle is braking, and the vehicle can be in a fourth state. That is, the controller can determine that the vehicle is decelerating due to braking.

[0039] The controller can determine the tilt of the vehicle along the surface it is traveling on based on position data. For example, if the vehicle's speed is observed to be increasing or decreasing on an uphill surface, the vehicle can be configured in a state where the controller disconnects the generator from the axles. This reduces engine fuel consumption during uphill travel where greater prime drive is required.

[0040] If location data indicates that a vehicle's speed is decreasing on a flat or downhill surface, meaning the vehicle is decelerating, the controller can be configured to engage a generator with the axles. During braking, energy is lost. Instead of dissipating all energy through the brakes, the generator can be engaged with the axles, allowing the energy that would otherwise be lost during braking to be converted back into electricity.

[0041] The controller can be configured to receive geographic data from a location determination device. The geographic data may be map data or topological data relating to the vehicle's location data. The controller can be configured to determine the slope on which the vehicle is traveling based on the geographic data corresponding to the vehicle's real-time location data.

[0042] Geographic data may be or include environmental data, such as weather data. The controller can be configured to determine one or more weather conditions affecting the vehicle based on geographic data corresponding to the vehicle's real-time location data. The controller can be configured to determine whether weather conditions, such as headwinds or tailwinds, are affecting the rate of change of the vehicle's speed.

[0043] The vehicle may include tilt sensors, such as accelerometers, for determining the vehicle's tilt angle. Tilt data from the tilt sensors can be used to determine whether the vehicle is traveling uphill or downhill.

[0044] The controller can be configured to determine the vehicle's speed. The controller can be configured to disconnect the generator from the axle when the vehicle's speed is less than the minimum speed required to generate electricity. Additionally, it may be necessary for the vehicle's speed to exceed the minimum speed for generating electricity to be in a second state. In other words, if the vehicle's speed is less than the minimum speed required to generate electricity via the generator, the controller can be configured to disconnect the generator from the axle or not connect the generator to the axle, even if other conditions would normally prompt for generator connection. Alternatively, the controller can be configured to disconnect the generator from the axle when the vehicle's speed exceeds the maximum speed required to generate electricity via the generator.

[0045] The power management system may include any of the one or more sensors mentioned above that are also used to determine the speed of the vehicle, such as wheel speed sensors or position determination devices.

[0046] The generator can be operated to generate electricity within a set rotational speed window. Therefore, the generator may not be able to generate electricity efficiently at all operating speeds of the vehicle, and thus it is more efficient to disconnect the generator from the axle when the vehicle is traveling at speeds outside the generator's operating window.

[0047] For example, when the vehicle speed is low, the generator may not be able to generate electricity efficiently. Therefore, below the minimum speed required to generate electricity, the generator can be disconnected from the axle, thus reducing fuel consumption when driving the vehicle at low speeds.

[0048] At lower speeds, the torque required by a rotating generator can be greater. Therefore, disconnecting the generator from the axle at low speeds reduces the prime mover required to drive the vehicle at low speeds, and consequently reduces fuel consumption at lower speeds. Thus, disconnecting the generator from the axle at low vehicle speeds increases fuel efficiency.

[0049] Alternatively, when vehicle speeds are high, the generator may not be designed to generate electricity efficiently. The axle rotation speed can be too high. Therefore, above the maximum speed used to generate electricity, the generator can be disconnected from the axle, thus reducing fuel consumption when driving the vehicle at high speeds.

[0050] The minimum speed for generating electricity using a generator may be at least 8 kph, at least 10 kph, at least 12 kph, at least 14 kph, or at least 16 kph. The maximum speed for generating electricity using a generator may be at most 96 kph, at most 98 kph, at most 100 kph, at most 102 kph, or at most 104 kph.

[0051] The controller is configured to engage or disengage the generator from the axles based on a determined state of the vehicle (i.e., determined operating conditions based on the vehicle and / or power management system). The generator may be selectively engaged with the axles using a clutch or other suitable arrangement. The controller may be configured to operate the clutch accordingly.

[0052] The generator can be configured to generate electricity at a rotational speed different from that of the axles. When vehicle speed varies during transport, the vehicle speed, and therefore the rotational speed of the axles, can differ from the optimal speed for operating the generator. The generator can be selectively coupled to the axles via a differential, allowing the generator to rotate at a different speed than the axles. This prevents wheel slippage if there is a large torque difference between the generator and the friction generated on the wheels due to contact with the drive surfaces. This also increases the efficiency of the generator's power generation, as the generator can be driven by the axles at a speed closer to the optimized rotational speed.

[0053] A transport refrigeration unit (TRU) typically includes one or more components, such as a compressor, evaporator fan, and condenser fan. The TRU components are powered by a power management system. The transport refrigeration unit can be operated to cool or heat the vehicle or the monitored environment within the vehicle, depending on the operating mode. The controller can be configured to operate the load-bearing components of the TRU based on the power level of the power management system (e.g., the state of charge of the energy storage device) or based on the energy generation rate of the generator.

[0054] The power management system may include a receiver. The receiver may be configured to receive data via wireless transmission. The receiver may be a wireless module.

[0055] The controller can communicate with a cloud network that can provide data relating to the vehicle's drive or data upon which to determine the rate of change of the vehicle's speed or whether the vehicle is braking. For example, if the vehicle is a trailer in a tractor-trailer system, the power management system can be configured to receive data relating to one or more operating parameters of the tractor, relayed via the cloud network. These operating parameters can be used to determine the corresponding operating parameters of the trailer. Alternatively, the data can relate to one or more operating parameters of the vehicle's engine management system, such that data relating to one or more operating parameters can be relayed from the engine management system to the power management system.

[0056] From a second aspect of the invention, a tractor-trailer system for transporting goods is provided, the tractor-trailer system comprising: a tractor for driving a trailer; and a trailer, wherein the trailer is a vehicle of the first aspect.

[0057] The tractor-trailer system of the second aspect may have one or more or all of the features (including optional features) of the vehicle of the first aspect. Therefore, the above description may also be applicable to the tractor-trailer system of the second aspect.

[0058] The tractor unit may include an engine management system. The engine management system may include multiple sensors configured to determine one or more operating parameters of the tractor unit. A controller may be configured to receive one or more of the operating parameters from the engine management system. The controller may be configured to determine the trailer speed or the rate of change of the trailer speed based on the operating parameters from the engine management system.

[0059] The tractor unit drives the trailer, and therefore the trailer will accelerate and brake together with the tractor unit. Accordingly, the operating parameters of the tractor unit can be equally applied to the trailer, and thus it is possible to determine the rate of change of the trailer's speed.

[0060] By determining the trailer's rate of change based on operating parameters from the engine management system, the power management system can more reliably determine the trailer's rate of change. Therefore, the power management system can more efficiently connect and disconnect the generator from the axles as needed, allowing the tractor to consume fuel more efficiently during tractor-trailer system operation.

[0061] One of the operating parameters may be the brake pedal position. The controller may be configured to determine whether the brake pedal is depressed and / or engaged. The controller may be configured to determine that the trailer is in a fourth state, and to connect the generator to the trailer when the vehicle is in the fourth state. When the vehicle is in the fourth state, the brake pedal may be depressed and / or engaged.

[0062] The brake pedal position will be understood as the position of the tractor's brake pedal. When the brake pedal is engaged, the tractor's braking system will be activated, causing the tractor-trailer system to decelerate, i.e., its rate of change of speed will be significantly less than zero. During braking, energy is lost from the tractor-trailer system. Instead of dissipating all the energy through the brakes, the generator can be engaged at the wheel axle, allowing the energy that would otherwise be lost during braking to be converted into electricity using the generator.

[0063] Other operating parameters may include, for example, tractor speed, accelerator pedal position, total fuel consumption, fuel level, engine speed, and vehicle distance. Operating parameters can be measured and / or determined using known sensors, technologies, or methods.

[0064] The engine management system may have one or more, or all, of the features of the engine management system of the first aspect. Therefore, the above description may also be applicable to the engine management system of the second aspect.

[0065] The engine management system can communicate wirelessly with the power management system. The engine management system can wirelessly connect to the power management system. This wireless connection can be considered a wireless interface. The engine management system can communicate wirelessly exclusively with the power management system. That is, there may be no wired and / or electrical contact connection between the power management system and the engine management system.

[0066] By providing an engine management system that communicates wirelessly with the power management system, a wired connection between the engine management system and the power management system is eliminated. Such a wired connection between the engine management system and the power management system can be complex and require regular maintenance. Furthermore, since trailers in a tractor-trailer system are interchanged among various tractors as part of a fleet, disconnecting and reconnecting wired transmissions can be time-consuming and error-prone. Moreover, wireless communication is less susceptible to user error due to its automatic rather than manual connection.

[0067] The provision of wireless connectivity also allows for reliable data transfer between the engine management system and the power management system. As described above, the engine management system may include multiple sensors configured to determine and / or measure one or more operating parameters of the tractor unit. These parameters may include one or more of the following: vehicle speed, clutch engagement, handbrake engagement, brake pedal position, cruise control engagement, accelerator pedal position, total fuel consumption, fuel level, engine speed, total axle load rating, total engine effective operating time, fuel management system data, vehicle identification number, driving recorder data, high-resolution vehicle distance, service distance, and engine coolant temperature.

[0068] By reliably transmitting operating parameters from the engine management system to the power management system, the power management system can more reliably manage power usage and regeneration, and can more accurately determine whether to connect the generator to the axle. Therefore, the reliable transmission of operating parameters and data between the power management system and the engine management system enables further optimization of the tractor's fuel consumption in the tractor-trailer system.

[0069] The trailer may include a first wireless module. The first wireless module can communicate with a controller. The first wireless module may be part of a power management system. The first wireless module may be configured to both transmit and receive wireless transmissions.

[0070] The tractor unit may include a second wireless module. This second wireless module can communicate with the engine management system. The second wireless module may be part of the engine management system. The second wireless module can be configured to both transmit and receive wireless transmissions.

[0071] The first wireless module can be configured to automatically connect to the second wireless module. The first and second wireless modules can also be configured to automatically connect when the first wireless module is within range of the second wireless module. For example, the first and second wireless modules can be configured to automatically connect when the trailer is attached to the tractor.

[0072] With automatic connection, a trailer can be easily and readily detached from a tractor unit before being attached to a second tractor unit. Upon attachment to the second tractor unit, a wireless module automatically connects, allowing the trailer to easily communicate with it. This enables easier interchangeability between tractor units and trailers, for example, as part of a fleet within a logistics network.

[0073] Because the first wireless module automatically identifies and detects the second wireless module, the first and second wireless modules can easily connect. The first wireless module can be configured to send a token or key to the second wireless module. The second wireless module can be configured to send an acknowledgment to the first wireless module in response to the token or key. As a result, the first and second wireless modules can connect.

[0074] The first wireless module can be located on the wall of the compartment adjacent to the tractor unit. The second wireless module can be located on or behind the rear wall of the tractor unit's compartment. Therefore, the first and second wireless modules can be positioned so that they are very close to each other when the trailer is attached to the tractor unit. As a result, the signal strength of the wireless connection can be improved compared to placing the wireless modules at opposite ends of the tractor-trailer system.

[0075] The first wireless module and the second wireless module can communicate via the CAN bus communication protocol. The first wireless module can communicate with the power management system via the CAN bus communication protocol. The second wireless module can communicate with the engine management system via the CAN bus communication protocol.

[0076] The first wireless module and / or the second wireless module may be configured to transmit and receive wireless communications using any known wireless communication protocol, including but not limited to: Bluetooth, Bluetooth Low Energy (BLE), ZigBee, 6LoWPAN, WiFi, 2G, 3G, 4G, 5G, NFC, RFID, LTE, or any other known wireless communication protocol.

[0077] In another aspect, a tractor-trailer system for transporting goods is provided, the tractor-trailer system comprising: a tractor for driving a trailer, wherein the tractor includes an engine management system; and a trailer, wherein the trailer includes a transport refrigeration unit and a power management system for providing power to the transport refrigeration unit; and wherein the power management system is wirelessly connected to the engine management system.

[0078] The tractor-trailer system may have one or more of the features of the vehicle of the first aspect and / or the tractor-trailer system of the second aspect. Therefore, the above description may also be applicable to the tractor-trailer system of the example described above.

[0079] From a third aspect of the invention, a method is provided for operating a power management system for providing power to a transport refrigeration unit, the method comprising: monitoring the rate of change of speed of a vehicle including an axle, the power management system, and the transport refrigeration unit; determining that the vehicle is in a first state, and disconnecting a generator from the axle while the vehicle is in the first state, wherein the speed of the vehicle is increasing in the first state; and determining that the vehicle is in a second state, and connecting the generator to the axle while the vehicle is in the second state, wherein the speed of the vehicle is constant in the second state.

[0080] The method of the third aspect may have one or more features corresponding to one or more of the features (including optional features) of the vehicle of the first aspect and / or the tractor-trailer system of the second aspect. Therefore, the above description may also be applicable to the method of the third aspect.

[0081] The third approach could be a method for operating the power management system of the vehicle described in the first approach. Attached Figure Description

[0082] Some exemplary embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings, in which: Figure 1A and Figure 1B The side and top views of the tractor-trailer system, including the power management system, are shown respectively. Figure 2 Showing the axle and generator; Figure 3 A graph showing how wheel torque changes with vehicle speed; Figures 4A to 4C Each diagram illustrates how power can be allocated by the power management system; Figure 5 A graph showing how generator power changes with vehicle speed; and Figure 6A and Figure 6B Each shows a side view of a tractor-trailer system, which includes a wireless communication interface between the tractor and the trailer. Detailed Implementation

[0083] Figure 1A A side view of trailer 1, including power management system 2 and transport refrigeration unit (TRU) 3, is shown. Trailer 1 is part of tractor-trailer system 100. Figure 1B A top view of the same tractor-trailer system 100 is shown. The tractor-trailer system 100 includes a tractor 4 that drives the trailer 1. The trailer 1 itself does not have a device for providing driving force. The tractor 4 includes an engine, such as a gasoline or diesel engine. The engine is part of an engine management system 5. The engine generates driving force through the combustion of fuel, which in turn drives the tractor-trailer system 100.

[0084] The tractor-trailer system 100 includes a plurality of wheels 6, each connected to an axle 10. At least one axle 10 is actively driven by the engine of the tractor 4. The remaining axles 10 are passively driven by the rotation of the wheels 6 using drive surfaces. Additionally, at least one of the passive axles 10 of the trailer 1 is selectively connected to an axle generator 11.

[0085] like Figure 2 As shown, generator 11 is connected to the shaft of axle 10 via gearbox 12. Axle 10 is configured to drive generator 11 when it is connected, so that electricity can be regenerated via the rotation of axle 10. Therefore, the tractor-trailer system 100 can regenerate electricity during the operation of the tractor-trailer system 100.

[0086] TRU 3 is powered by power management system 2. Power management system 2 is arranged to supply electrical power to TRU 3 so that the energy needs of TRU 3 are met. Power management system 2 includes generator 11 and additionally includes energy storage devices such as rechargeable battery 13. Depending on the needs of TRU 3, power management system 2 supplies electrical power to TRU 3 via generator 11 and / or battery 13. TRU 3 includes several components that require power, including compressor, condenser fan, and evaporator fan. When the tractor-trailer system 100 is not in transit, battery 13 can also be recharged by connecting to an external power source such as power grid 21.

[0087] The power management system 2 can meet the power demand of TRU 3 for a longer period of time without using the power grid 21 to recharge the battery 13, because the power demand can be met or supplemented by the generator 11.

[0088] The use of generator 11 and battery 13 avoids the need for a separate fuel-burning generator within trailer 1. However, when generator 11 is coupled to axle 10, generator 11 increases the torque on axle 10, and therefore requires greater prime drive to power the tractor-trailer system 100. This will increase the engine's fuel consumption rate during trailer 1 transport.

[0089] Figure 3 The diagram illustrates how the torque at wheel 6 changes with vehicle speed when generator 11 is connected to axle 10 and when generator 11 is not connected to axle 10. The torque at wheel 6 is greater at lower vehicle speeds and decreases as vehicle speed increases. The engine torque at wheel 6 is also greater when generator 11 is connected to axle 10 than when generator 11 is not connected to axle 10. Therefore, when generator 11 is connected to axle 10, the engine must provide a greater prime drive to provide the necessary engine torque to rotate wheel 6. The prime drive provided by the engine is proportional to the engine's fuel consumption rate, and therefore connecting generator 11 to the axle increases the engine's fuel consumption rate.

[0090] Therefore, there are several possibilities, among which it is advantageous to disconnect the generator 11 from the axle 10, thereby reducing the force required to drive the tractor-trailer system 100 and also reducing fuel consumption. By selectively connecting and / or disconnecting the generator 11 from the axle 10 depending on a specific state of the tractor-trailer system 100, the fuel consumption efficiency of the tractor-trailer system 100 can be improved.

[0091] The power management system 2 includes a controller 20. The controller 20 is configured to determine the state of the tractor-trailer system 100, and the controller 20 is configured to connect or disconnect the generator 11 from the axle 10 depending on the current state of the tractor-trailer system 100.

[0092] When a vehicle is accelerating, the engine's fuel consumption rate typically increases because the power required for acceleration is greater than the power required to drive the vehicle at a steady speed. Connecting the generator 11 to the axle 10 further increases the power required to accelerate the tractor-trailer system 100 when the vehicle is accelerating. Therefore, during acceleration, when the generator 11 is connected to the axle 10, the fuel consumption rate of the engine driving the tractor-trailer system 100 increases further.

[0093] As the engine requires greater power, its fuel efficiency tends to decrease. Therefore, disconnecting the generator 11 from the axle 10 during acceleration can improve the engine's fuel efficiency. Therefore, the controller 20 is configured to consider the acceleration of the tractor-trailer system 100 when determining the current state of the tractor-trailer system 100.

[0094] Therefore, it is generally desirable for the controller 20 to connect the generator 11 to the axle 10 when the tractor-trailer system 100 is at a substantially constant speed, and to disconnect the generator 11 from the axle 10 when the tractor-trailer system 100 is accelerating. However, other conditions can also affect whether the power generated from the generator 11 is suitable and necessary. Therefore, the controller 20 is configured to consider the current state of the tractor-trailer system 100 as a whole when determining whether to connect or disconnect the generator 11 to the axle 10.

[0095] The controller 20 is configured to disconnect the generator 11 from the axle 10 when it is determined that the tractor-trailer system 100 is in a first state in which the tractor-trailer system 100 is accelerating and there is no need to generate power at this time. Therefore, at least when it is determined that the tractor-trailer system 100 is in the first state, the prime mover required by the engine to accelerate the tractor-trailer system 100 can be reduced compared to the case where the generator 11 remains connected to the axle 10, and as a result, the fuel efficiency of the tractor-trailer system 100 can be improved.

[0096] When controller 20 determines that the tractor-trailer system 100 is in the second state, controller 20 is configured to connect generator 11 to axle 10, so that electricity can be generated by generator 11 to power TRU 3. In the second state, the speed of tractor-trailer system 100 remains substantially constant, and the state of tractor-trailer system 100 is otherwise suitable for power generation. Although connecting generator 11 to axle 10 increases the engine's fuel consumption rate, the increase in fuel consumption rate in this state will have a smaller impact on fuel efficiency compared to when tractor-trailer system 100 is accelerating. Therefore, TRU 3 can still be powered by generator 11 while managing engine fuel consumption more efficiently.

[0097] It will be understood that, ideally, when the tractor-trailer system is accelerating, the generator 11 will be disconnected from the axle 10, and ideally, when the speed of the tractor-trailer system 100 remains constant, the generator 11 will be connected to the axle 10. In this way, the power management system 2 can improve fuel efficiency while still supplying sufficient power to the TRU 3 via the generator 11. However, there are multiple criteria that the controller 20 can consider in various embodiments, such that the TRU 3 is always supplied with sufficient power, or that the generator 11 is not unnecessarily connected to the axle 10. Therefore, the corresponding criteria for whether the vehicle speed is increasing or the vehicle speed is constant in each of the first and second states are not necessarily the only criteria that the controller 20 needs to meet to determine whether the tractor-trailer system 100 is in any of those particular states.

[0098] Figures 4A to 4C The diagram schematically illustrates how power is supplied to the TRU 3 by the power management system 2. The controller 20 is configured to monitor the power generation rate of the generator 11, the state of charge of the battery 13, and the power demand of the TRU 3. Depending on each of these monitored variables and the specific state of the vehicle, the power management system 2 supplies power to the TRU 3 accordingly.

[0099] like Figure 4A As shown, when the power generation rate of generator 11 exceeds the power demand of TRU 3, the power management system 2 is configured to use generator 11 to provide power to TRU 3, and also simultaneously use generator 11 to recharge battery 13. Therefore, this is only possible when generator 11 is connected to axle 10.

[0100] like Figure 4BAs shown, when the power demand of TRU 3 exceeds the generation rate of generator 11, the power management system 2 is configured to use both generator 11 and battery 13 to provide power to TRU 3. Therefore, generator 11 and battery 13 can supply power to TRU 3 simultaneously. Again, it is evident that this is only possible when generator 11 is connected to axle 10.

[0101] When the generator 11 is not connected to the axle 10 (i.e., the generator 11 does not generate electricity), the TRU 3 is powered solely by the battery 13. This is typically the case when the tractor-trailer system 100 is accelerating.

[0102] Since the power management system 2 may need to use only battery 13 to power the TRU 3, the power management system 2 is configured to recharge battery 13 when its charge is insufficient. This helps the power management system 2 ensure that there is sufficient available power (at least in reserve) to power the TRU 3.

[0103] As stated above, controller 20 monitors the state of charge (SOC) of battery 13. When the SOC of battery 13 falls below a first threshold, controller 20 is configured to connect generator 11 to axle 10, regardless of any other determined criteria. For example, even if the tractor-trailer system 100 is accelerating, controller 20 will still connect generator 11 to axle 10 if the SOC of battery 13 is not determined to be sufficient. In other words, controller 11 can be configured to connect generator 11 to axle 10 when the SOC of battery 13 falls below a first threshold (even in other undesirable conditions). The first threshold can be considered a low battery threshold and, in various embodiments, can correspond to at least 20% SOC. Therefore, power management system 2 prioritizes adequate charging of battery 13 so that the power requirements of TRU 3 can be reliably met.

[0104] Figure 4C This illustrates how the power management system 2 allocates power to the TRU 3 in a third scenario where generator 11 provides power solely to the TRU 3. Generator 11 can provide power solely to the TRU 3 when the generation rate of generator 3 meets the power requirements of the TRU 3.

[0105] By disconnecting the generator 11 from the axle 10 when the battery 13 is sufficiently charged and using only the battery 13 to power the TRU 3 until the battery 13 has been discharged to a given level, the fuel efficiency of the tractor-trailer system 100 can be improved. Therefore, the controller 20 can determine when the tractor-trailer system 100 is in a third state in which the state of charge of the battery 13 is greater than a second threshold. The second threshold corresponds to the battery 13 being sufficiently charged, and in various embodiments, this may correspond to the battery being at least at 95% capacity. When the controller 20 determines that the battery 13 is sufficiently charged, it will disconnect the generator 11 from the axle 10 even if the state of the tractor-trailer system 100 is otherwise suitable for generating power.

[0106] When battery 13 is fully charged, power management system 2 uses only battery 13 to power TRU 3. TRU 3 is powered by battery 13 until battery 13 has been discharged to a given level, which in many embodiments is at least 15%. Once battery 13 is no longer fully charged, controller 20 may, depending on the current state of tractor-trailer system 100, reconnect generator 11 to or disconnect it from axle 10 to optimize fuel consumption of tractor-trailer system 100.

[0107] In an alternative embodiment, when the generation rate exceeds the power demand and the battery 13 is sufficiently charged to prevent it from storing excess power, the generator 11 may provide power solely to the TRU 3. In this alternative embodiment, the excess power is dissipated elsewhere (e.g., via a heat exchanger) or delivered to other components of the power management system 2.

[0108] Figure 5 This illustrates how the power generation rate of generator 11 varies with vehicle speed. Generator 11 generates power based on its rotational frequency, which is in turn controlled by gearbox 12 depending on the speed of tractor-trailer system 100. Generator 11 does not generate sufficient power at low rotational frequencies. Therefore, tractor-trailer system 100 may not always travel at a speed high enough for generator 11 to generate power. When tractor-trailer system 100 travels at a speed insufficient to utilize the power generated by generator 11, disconnecting generator 11 from axle 10 reduces the prime mover required to drive tractor-trailer system 100, and thus improves engine fuel efficiency at lower speeds compared to keeping generator 11 connected to axle 10.

[0109] Controller 20 is configured to determine whether the tractor-trailer system 100 is in a state where the speed of the tractor-trailer system 100 is below the minimum speed for generating electricity. In various embodiments, the minimum speed is at least 12 kph. In at least one of the states where the speed of the tractor-trailer system 100 is below the minimum speed for generating electricity, controller 20 is configured to disconnect generator 11 from axle 10. This state may be an additional state to the states mentioned above. In each of these states, when the speed of the tractor-trailer system 100 is not high enough to allow the generator 11 to generate electricity, disconnecting generator 11 from axle 10 may improve the fuel efficiency of the tractor-trailer system 100, as the force required to drive the vehicle does not need to be increased unnecessarily. Conversely, it may be necessary for the tractor-trailer system 100 to be in a state where its speed is equal to or greater than the minimum speed for generating electricity in order to connect generator 11 to axle 10.

[0110] The controller 20 is also configured to determine whether the tractor-trailer system 100 is braking. If the tractor-trailer system 100 is braking, any electricity generated by connecting the generator 11 to the wheel axle 10 can be considered “free energy” because increasing the torque acting on the wheel 6 is desirable to enhance braking performance.

[0111] The controller 20 determines whether the tractor-trailer system 100 is in a state in which the tractor-trailer system 100 is braking. One of these states can be considered a "fourth" state. At least when it is determined that the tractor-trailer system 100 is in the fourth state, the controller connects the generator 11 to the axle 10. In this way, the energy that would otherwise be lost due to braking is regenerated.

[0112] In various embodiments, the controller 20 determines that the tractor-trailer system 100 is braking by monitoring the position of the brake pads or the brake pedal of the tractor 4. When the brake pedal is pressed, the tractor-trailer system 100 is determined to be braking.

[0113] The power management system 2 uses various methods to monitor the speed of the trailer 1 (and therefore the tractor-trailer system 100). In one embodiment, the power management system 2 includes wheel speed sensors arranged to monitor the rotational speed of the wheels 6. The power management system 2 may also include a position detection device 25, such as a GPS device. The position detection device 25 provides real-time position data to the controller 20 of the power management system 2, allowing the speed of the trailer 1 to be determined. In this context, real-time will be understood to mean at least within the most recent 0.5 seconds.

[0114] By providing one or more sensors or devices to monitor the speed of trailer 1, the power management system 2 can monitor and / or determine the speed of the tractor-trailer system 100 independently of any data generated by the engine management system 5. This is advantageous when the tractor-trailer system 100 is part of a fleet and trailer 1 is interchanged between tractors 4 at various stages during transport, as the connection from trailer 1 to tractor 4 can be simplified and / or faster without the need to physically connect the engine management system 5 of the tractor 4 to the power management system 2 of trailer 1.

[0115] In a preferred embodiment, the power management system 2 communicates with the engine management system 5, enabling the controller 20 to receive one or more operating parameters of the tractor 4 from the engine management system 5. Since the trailer 1 and the tractor 4 are connected in the tractor-trailer system 100, many operating parameters applied to the tractor 4 also represent the operating parameters of the tractor-trailer system 100 as a whole. Therefore, the operating parameters of the tractor 4 can be used by the power management system 2 to determine the state of the tractor-trailer system 100.

[0116] Operating parameters include the brake pedal position. The brake pedal position provides an indication of whether the brakes of the tractor 4 are engaged and therefore whether the tractor-trailer system 100 is braking. As discussed above, the tractor-trailer system 100 is braking in the fourth state, and therefore, by monitoring the brake pedal position of the tractor 4, the controller 20 can determine whether the tractor-trailer system 100 is in the fourth state.

[0117] Other operating parameters provided by the engine management system 5 include: tractor speed, accelerator pedal position, total fuel consumption, fuel level, engine speed, and vehicle distance. These operating parameters are determined and / or monitored using known sensors and technologies.

[0118] To transmit operating parameters to the power management system 2, the engine management system 5 is connected to the power management system 2. In one embodiment, the power management system 2 may communicate with the engine management system 5 via a wired connection. However, establishing a wired connection can be complex and can increase the time spent changing trailers 1 between tractor units 4 in a fleet.

[0119] Figure 6AA wireless communication interface between an engine management system 5 and a power management system 2 according to a preferred embodiment is shown. The power management system 2 communicates with a first wireless module 31, and the engine management system 5 communicates with a second wireless module 32. The first wireless module 31 and the second wireless module 32 communicate wirelessly with each other, enabling the engine management system 5 and the power management system 2 to communicate wirelessly with each other. That is, the first wireless module 31 and the second wireless module 32 provide a wireless communication interface for the engine management system 5 and the power management system 2. The first wireless module 31 and the second wireless module will communicate via the CAN bus communication protocol, and each uses the CAN bus communication protocol to communicate with the power management system 2 and the engine management system 5 respectively.

[0120] The first wireless module 31 is positioned facing forward of the trailer 1, adjacent to the TRU 3. The second wireless module 32 is positioned facing backward of the tractor 4. In this way, due to the way the trailer 1 is connected to the tractor 4, the distance between the first wireless module 31 and the second wireless module 31 is reduced, and the wireless communication strength between the two modules is stronger than if they were located at opposite ends of the tractor-trailer system 100.

[0121] The first wireless module 31 is configured to automatically connect to the second wireless module 32 when the trailer 1 is attached to the tractor 4. The communication link is established using known methods and technologies. For example, the first wireless module 31 may be configured to send a token or key to the second wireless module 32, which is recognized and acknowledged by the second wireless module 32. The wireless interface uses any known wireless communication protocol, such as Bluetooth, Bluetooth Low Energy (BLE), ZigBee, 6LoWPAN, WiFi, 2G, 3G, 4G, 5G, NFC, RFID, LTE, or any other known wireless communication protocol.

[0122] By providing a wireless communication interface between the engine management system 5 and the power management system 2, it is easier to establish a communication link between the trailer 1 and the tractor 4, which are part of the fleet. In addition, the power management system 2 can receive more accurate data from the engine management system 5 related to the operation of the tractor-trailer system 100, so that the status of the tractor-trailer system 100 can be determined more reliably.

[0123] Figure 6B An alternative wireless communication interface between the engine management system 5 and the power management system 2 is shown. The first wireless module 31 is located adjacent to the power management system 2, rather than at the front of the trailer 1. The wireless communication interface is similar to... Figure 6A It works as shown in the wireless communication interface.

Claims

1. A vehicle (1) for transporting goods, said vehicle (1) comprising: Wheel axle (10); Transport refrigeration unit (3); and A power management system (2) is used to supply power to the transport refrigeration unit (3); The power management system (2) includes: A generator (11) configured to be selectively coupled to an axle (10) of the vehicle (1), wherein the generator (11) is configured to generate electricity when coupled to the axle (10); and A controller (20) configured to monitor the speed of the vehicle (1) and selectively connect and disconnect the generator (11) from the axle (10); The controller (20) is configured to determine that the vehicle (1) is in a first state and disconnect the generator (11) from the axle (10) when the vehicle (1) is in the first state, wherein the speed of the vehicle (1) is increasing in the first state; and The controller (20) is configured to determine that the vehicle (1) is in a second state and to connect the generator (11) to the axle (10) when the vehicle (1) is in the second state, wherein the speed of the vehicle (1) is substantially constant in the second state.

2. The vehicle (1) according to claim 1, wherein, The power management system (2) includes an energy storage device (13) capable of providing power to the transport refrigeration unit (3); and The generator (11) is configured to selectively recharge the energy storage device (13).

3. The vehicle (1) according to claim 2, wherein, The controller (20) is configured to: Monitor the power requirements of the transport refrigeration unit (3); and Monitor the power generation rate of the generator (11); and If the power generation rate exceeds the power demand, power is supplied to the transport refrigeration unit (3) via the generator (11) and the energy storage device (13) is recharged; and If the power demand exceeds the generation rate, power is supplied to the transport refrigeration unit (3) via the generator (11) and the energy storage device (13).

4. The vehicle (1) according to claim 2 or 3, wherein, The controller (20) is configured to monitor the state of charge of the energy storage device (13); and Wherein, the state of charge of the energy storage device (13) is less than the first threshold in the second state.

5. The vehicle (1) according to claim 4, wherein, The controller (20) is configured to determine that the vehicle (1) is in a third state and disconnect the generator (11) from the axle (10) when the vehicle (1) is in the third state, wherein the state of charge exceeds a higher second threshold in the third state.

6. The vehicle (1) according to any one of claims 1-3, wherein, The vehicle (1) includes a location determination device (25) configured to provide real-time location data to the vehicle (1); and The controller (20) is configured to receive the real-time location data from the location determination device (25) and determine the rate of change of the speed of the vehicle (1) based on the real-time location data.

7. The vehicle (1) according to any one of claims 1-3, wherein, The controller (20) is configured to receive braking data for the vehicle (1); and The controller (20) is configured to determine that the vehicle (1) is in a fourth state and to connect the generator (11) to the axle (10) when the vehicle (1) is in the fourth state, wherein the vehicle (1) is braking in the fourth state.

8. The vehicle (1) according to any one of claims 1-3, in, The speed of the vehicle (1) in the second state is higher than the minimum speed required for generating electricity; and The controller (20) is configured to disconnect the generator (11) from the axle (10) when the speed of the vehicle is less than the minimum speed for generating electricity.

9. A tractor-trailer system (100) for transporting goods, the tractor-trailer system (100) comprising: A tractor (4) is used to drive a trailer (1); and The trailer (1) is a vehicle according to any of the preceding claims.

10. The tractor-trailer system (100) according to claim 9, wherein, The tractor (4) includes an engine management system (5) which includes a plurality of sensors configured to monitor one or more operating parameters of the tractor (4); and The controller (20) is configured to receive one or more of the operating parameters from the engine management system (5) and determine the status of the trailer (1) based on the operating parameters.

11. The tractor-trailer system (100) according to claim 10, wherein, The one or more operating parameters include brake pedal position; and The controller (20) is configured to determine that the trailer (1) is in a fourth state and to connect the generator (11) to the axle (10) when the trailer (1) is in the fourth state, wherein the brake pedal is pressed in the fourth state.

12. The tractor-trailer system (100) according to claim 10 or 11, wherein, The one or more operating parameters include brake pedal position; and The controller (20) is configured to determine that the trailer (1) is in a fifth state and disconnect the generator (11) from the axle (10) when the trailer (1) is in the fifth state, wherein the trailer (1) is decelerating and the brake pedal is not pressed.

13. The tractor-trailer system (100) according to claim 10 or 11, wherein, The engine management system (5) communicates wirelessly with the power management system (2).

14. The tractor-trailer system (100) according to claim 13, wherein, The trailer (1) includes a first wireless module (31) that communicates with the power management system (2); The tractor (4) includes a second wireless module (32) that communicates with the engine management system (5); and The first wireless module (31) and the second wireless module (32) are configured to automatically connect when the trailer (1) is attached to the tractor (4).

15. A method of operating a power management system (2) for providing power to a transport refrigeration unit (3), the method comprising: The speed of the vehicle (1) is monitored, the vehicle including axles (10), the power management system (2) and the transport refrigeration unit (3); Determine that the vehicle (1) is in a first state, and disconnect the generator (11) from the axle (10) while the vehicle (1) is in the first state, wherein the speed of the vehicle (1) is increasing in the first state; and The vehicle (1) is determined to be in a second state, and the generator (11) is connected to the axle (10) when the vehicle (1) is in the second state, wherein the speed of the vehicle (1) is constant in the second state.

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