Controlling a Cooling System Water Intake Pump of an Electric Marine Vessel

The present disclosure relates to methods, apparatuses, and computer program products for controlling a cooling system water intake pump of an electric marine vessel.

Advances in battery technology have paved the way for full-electric vehicles. Building on those advances, technology to enable full-electric watercraft has been widely adopted. However, the challenges of designing electric vehicles are different from the challenges of designing electric boats. The transformation of existing watercraft platforms to a full-electric platform also poses a different set of challenges.

According to embodiments of the present disclosure, various methods, apparatuses, and computer program products for controlling a cooling system water intake pump of an electric marine vessel are described herein. In some aspects, a pump controller receives information describing an operating state of an electric propulsion device of a marine vessel, where the information indicates at least one of a motor speed of an electric motor and temperature readings within the electric propulsion system. The pump controller controls a water intake pump of a cooling system for the electric propulsion device based on the received information.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular descriptions of exemplary embodiments of the invention as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts of exemplary embodiments of the invention.

Advances in battery technology have paved the way for full-electric vehicles. Building on those advances, technology to enable full-electric watercraft has been widely adopted. However, the challenges of designing electric vehicles are different from the challenges of designing electric boats. The transformation of existing watercraft platforms to a full-electric platform also poses a different set of challenges.

In a conventional internal combustion engine (‘ICE’) marine outboard motor, a pump in a lower unit of the outboard motor situated below the water line draws ambient water into the motor's cooling system for cooling engine components. Circulation lines in the cooling system circulate the cooling water throughout the engine block and other engine components. Heat is exchanged between the engine components and the cooling water, and the heated water is then pumped back into the ambient water supply. Typically, a cooling system water intake pump includes an impeller that is driven by the same drive shaft that drives the outboard propeller. Rotation of the drive shaft rotates the impeller to create suction to pump the water into the cooling system. As the engine speed increases, thus generating more heat, the pump speed also increases due to the faster rotation of the drive shaft, thus supplying a greater flow of water to cool the engine. Because the pump impeller is mechanically coupled to the drive shaft, the pump runs continuously as long as the engine is idling, even if no mechanical power is applied to the propeller (i.e., the propeller gearbox is in neutral). Similarly, if the engine is off, the cooling system pump is also off. This mechanism for controlling the cooling system intake pump is not well-suited for electric marine vessels.

Because electric marine motors do not rely on internal combustion, such motors do not have an ‘idle’ state in which the drive shaft is continuously spinning. Rather, when no mechanical power is required of the motor, electrical current delivered to the electric motor ceases and the electric motor simply stops. As such, a cooling system intake pump coupled to the drive shaft would not operate while the electric motor is stopped. However, it may be advantageous to continue to cool the electric motor even when the motor has momentarily stopped. Moreover, electric motors are substantially quieter than ICE systems. Thus, the operation of a cooling system pump that is coupled to a drive shaft may, at times, produce a substantial amount of audible noise. When not masked by ICE motor noise, the noise generated by the operation of the intake pump is readily perceptible, and an otherwise silent boating experience afforded by the electric motor is impeded upon by the noise of the cooling system intake pump. At times, the cooling needs of the electric propulsion system may not require the impeller of the intake pump to rotate as the same speed as the drive shaft. At these times, the intake pump is generating an unnecessary amount of noise. It is therefore advantageous to mechanically decouple the intake pump from the drive shaft of the propulsion system and operate the cooling system intake pump independently based on the cooling needs of the electric propulsion system.

To address these and other issues, controlling a cooling system water intake pump of an electric marine vessel in accordance with the present disclosure provides a cooling system intake pump that is decoupled from the drive shaft and controlled independently based on the cooling needs of the electric motor. The cooling system intake pump is controlled in response to data describing the state of the electric propulsion system, such as data describing temperature readings, cooling system water flow rate, mechanical speed of the motor, pump impeller speed, and other state information that will be described in more detail below. Thus, the intake pump control system described herein mitigates unnecessary acoustic noise generated by the operation of the intake pump. Further, the intake pump control system described herein extends the life of the intake pump.

sets forth an example electric vesselfor controlling a cooling system water intake pump of an electric marine vessel in accordance with the present disclosure.is provided to emphasize the powertrain components of vessel. It will be appreciated that vesselmay include other components not shown or described herein. Vesselmay be any type of watercraft. In a particular example, vesselincludes a full-electric powertrain and thus may also referred to as an ‘electric boat.’ To that end, vesselincludes a marine propulsion system. For example, marine propulsion systemmay be a full-electric outboard motor or inboard motor with a propeller, or a full-electric jet craft with an impeller. The marine propulsion system is described in more detail below with reference to.

The marine propulsion systemis powered by one or more high voltage batteries. In the example, of, two high voltage batteriesare shown; however, it will be appreciated a vesselin accordance with the present disclosure may include fewer or more high voltage batteries. High voltage batteries operate at voltages ranging from a few hundred to over 800 volts, depending on the design and application. Higher voltages allow for more efficient power transmission and reduced current flow, which helps minimize energy losses. Each high voltage batteryincludes multiple modules, each containing several individual battery cells connected in series and parallel configurations to achieve the desired voltage and capacity. These cells may be arranged in a pack that optimizes space utilization and facilitates thermal management. Each high voltage batteryincludes or is coupled to a battery management system (BMS). The BMS is responsible for monitoring and controlling various parameters such as voltage, current, temperature, and state of charge (SoC) of individual cells within the pack. The BMS helps optimize battery performance, protect against overcharging or over-discharging, and ensures safety. The BMS communicates with other vessel components about battery state, receives commands to change the battery state, and controls the opening and closing of the main contactors in the battery. The high voltage batteryis described in more detail below with reference to.

The marine propulsion systemreceives power from the high voltage batteryvia a power distribution unit (PDU). The PDUreceives high-voltage DC power from the high voltage batteriesand routes it to different subsystems and components within vessel, such as the electric marine propulsion systemand other subsystems such as a DCDC converter. The PDUalso couples the high voltage batteriesto a charging portfor charging the high voltage batteries. The PDU, as explained in more detail below with reference to, includes a set of contactors that are controlled by logic or software in the PDUto ensure safety when switching the flow of power among various vessel components.

The DCDC converterprovides voltage conversion capabilities to step down the high-voltage DC power to lower voltages required by an auxiliary system, such as the 12-volt electrical system used for lights, accessories, and onboard electronics. The DCDC convertermay be used to charge a lower voltage battery such as a 12-volt marine battery.

Vesselfurther includes a vessel control unit. Vessel control unitserves as the central control unit responsible for managing and coordinating various functions and systems onboard the vessel. For example, the vessel control unitcan provide propulsion control, including regulating engine speed, torque, and direction to achieve desired propulsion performance and maneuverability in accordance with commands or signals received from the vessel's throttle control. The vessel control unitcan also manage the vessel's steering system. The vessel control unitcan also control startup/shut down routines, control charging/operation mode selection, control the opening and closing of contactors in the PDU, monitor the state of onboard systems, perform vessel diagnostics, and interface with an operator dashboard. To that end, the vessel control unitmay communicate with the other vessel powertrain components (e.g., the marine propulsion system, the high voltage battery, the PDU, the DCDC converter, and so one) via a control area network (CAN), referred to herein as a CAN bus. The vessel control unitwill be described in more detail below with reference to.

The CAN busmay be a two-wire serial bus that allows multiple components and devices within a vessel to communicate with each other without a host computer. The CAN busmay use a message-based communication scheme where components and devices send and receive data in the form of messages. Each message includes a CAN identifier (CAN ID), data bytes, and control bits. The CAN busmay employ a multi-master architecture, in that any device on the network can initiate a message transmission. This distributed architecture allows for efficient communication between vessel components without the need for a centralized controller. In a particular example, the CAN busmay implement the NMEA2000 protocol, a standard set forth by the National Marine Electronics Association. NMEA2000 provides optimization and messaging for a marine environment.

Vesselcan also include a high voltage interlock loop (HVIL) system, which is a safety feature designed to ensure the safe operation and maintenance of the high-voltage components. HVIL is a dedicated circuit that ensures the high voltage connectors are well inserted in the equipment mating connector to ensure the safety of the high voltage connections. HVIL is used by the high voltage battery BMS and the vessel control unitto confirm the integrity of these connections before applying high voltage energy to each high voltage device in the vessel.

For ease of reference, inpower interconnectssupplying high voltage power are shown in hash-filled lines, data interconnects for CAN busare shown in thick solid black lines, and HVIL interconnectsare shown in dashed lines.

For further explanation,sets forth a block diagram of an example of the electric marine propulsion systemin accordance with at least one embodiment of the present disclosure. The example marine propulsion systemofincludes a CAN interfacefor coupling the marine propulsion systemto the CAN bus. For example, the CAN interfacemay be a network interface controller configured to send and receive messages in the form of CAN frames over the CAN bus.

The example marine propulsion systemalso includes a controllercoupled to the CAN interface. The controllermay include or implement a processor, a microcontroller, an Application Specific Integrated Circuit (ASIC), a programmable logic array (PLA) such as a field programmable gate array (FPGA), or other data processing unit in accordance with the present disclosure. In some examples, the controller is implemented by a processor or central processing unit configured to execute computer programming instructions, also referred to a computer executable instructions or processor executable instruction. Such instruction can be loaded from and stored in one or more memory devices collectively referred to as storage. Storagemay include electrically erasable programmable read-only memory (EEPROM) such as Flash memory (e.g., NAND and NOR flash memory or other types of solid-state memory), dynamic random-access memory (DRAM), static RAM (SRAM), magnetic disk storage, and the like. The storagemay be integrated with the controlleror provided as a separate memory device coupled to the controller.

The marine propulsion systemalso includes an inverterthat that is powered by the high voltage batteries. The inverterfunctions to convert the DC current received from the high voltage batteriesto alternating current (AC) that can be used by an electric motor. In some examples, the inverteris a high voltage two-phase DC to a high voltage three-phase AC converter. The marine propulsion system also includes an electric motorcoupled to a propeller/impeller. The electric motoris powered by the current received from the inverter. The electric motoris an electric traction motor that turns a drive shaft (not shown) that drives the propeller/impeller. In some examples, the electric motor is a permanent magnet electric motor. The electric motoris designed to withstand exposure to water and corrosive marine environments, featuring waterproof enclosures, sealed bearings, and corrosion-resistant materials to ensure reliable operation in wet conditions. The electric motoroperates quietly, producing minimal noise and vibration compared to traditional combustion engines, which contributes to a quieter boating experience as well as reduced noise pollution in aquatic environments. The electric motoroffers high efficiency and energy density, allowing electric boats to achieve comparable performance to traditional boats powered by combustion engines while using less energy and producing fewer emissions.

A control programembodied in computer programing instructions is stored within tangible persistent storage of storage. When executed by the controller, the control programis configured to receive commands from the vessel control unitand control the electric motorin accordance with those commands. For example, the control programmay be configured to regulate the distribution of electrical energy from the inverterto the electric motor. In this example, the control programmay receive a throttle/speed command from the vessel control unitand determine the frequency variation or voltage variation that will enter the electric motorfor controlling the vessel's speed. The control programis further configured to receive motor state information from various sensors (not shown) and supply motor state information and diagnostic information to the vessel control unit. Also stored in tangible persistent storage of storageis a pump controller programfor controlling a cooling system water intake pump of the marine propulsion system. The pump controller programreceives information describing an operating state of an electric propulsion device of a marine vessel. The information indicates at least one of a motor speed of an electric motor and temperature readings within the electric propulsion system. The pump controller programcontrols a water intake pump of a cooling system for the electric propulsion device based on the received information. Additional aspects of the pump controller will be described in more detail below.

For further explanation,sets forth a block diagram of an example of the high voltage batteryin accordance with at least one embodiment of the present disclosure. The example high voltage batteryofincludes a CAN interfacefor coupling the high voltage batteryto the CAN bus. For example, the CAN interfacemay be a network interface controller configured to send and receive messages in the form of CAN frames over the CAN bus. The example high voltage batteryincludes array of battery cellsorganized into battery modulesor battery packs, and a set of battery contactorsthat selectively couple the battery modulesto high voltage terminalsof the battery.

The example high voltage batteryalso includes a battery management system (BMS)comprising a controllercoupled to the CAN interface. Controllermay include or implement a processor, a microcontroller, an ASIC, PLA such as an FPGA, or other data processing unit in accordance with the present disclosure. In some examples, controlleris implemented by a processor or central processing unit configured to execute computer programming instructions, also referred to a computer executable instructions or processor executable instruction. Such instructions can be loaded from and stored in one or more memory devices collectively referred to as storage. Storagemay include EEPROM such as Flash memory (e.g., NAND and NOR flash memory or other types of solid-state memory), DRAM, SRAM, magnetic disk storage, and the like. The battery management systemfurther includes a variety of sensors (not shown) coupled to battery cells for measuring battery state information. The storagemay be integrated with the controlleror provided as a separate memory device coupled to the controller.

The BMSincludes a control programembodied in computer programing instructions stored in tangible persistent storage of storage. In some examples, the control programcontrols the state of the battery contactors for selectively coupling and decoupling the battery modulesto the high voltage terminalsof the battery. In some examples, the control programalso monitors battery state information such as voltage, current, and temperature in battery cellsvia the above-mentioned sensors. In some examples, the control programalso communicates with the vessel control unitto provide battery state information. The control program also controls the charging of the battery cells.

For further explanation,sets forth a block diagram of an example of the PDUin accordance with at least one embodiment of the present disclosure. The example PDUofincludes a CAN interfacefor coupling the PDUto the CAN bus. For example, the CAN interfacemay be a network interface controller configured to send and receive messages in the form of CAN frames over the CAN bus. The PDUalso includes a battery interfacecoupling the high voltage batteriesto a switching systemof the PDU, a charge port interfacecoupling the charging portto the switching system, a motor interfacecoupling the marine propulsion systemto the switching system, and a DCDC interfacecoupling the DCDC converterto the switching system. The switching systemincludes a set of contactors (not shown for simplicity) by which the PDUsupplies power from the high voltage batteriesto the marine propulsion systemand to the DCDC converter, or supplies power from the charging portto the high voltage batteries.

The example PDUalso includes a controllerthat may include or implement a processor, a microcontroller, an ASIC, PLA such as an FPGA, or other data processing unit in accordance with the present disclosure. In some examples, the controlleris implemented by a processor or central processing unit configured to execute computer programming instructions, also referred to a computer executable instructions or processor executable instruction. Such instructions can be loaded from and stored in one or more memory devices collectively referred to as storage. Storagemay include EEPROM such as Flash memory (e.g., NAND and NOR flash memory or other types of solid-state memory), DRAM, SRAM, magnetic disk storage, and the like. The storagemay be integrated with the controlleror provided as a separate memory device coupled to the controller.

The PDUalso includes a control programembodied in computer programing instructions stored in tangible persistent storage of storage. When executed by the controller, the control programis configured to receive commands from the vessel control unitand control the switching systemto connect and disconnect power supplied to vessel components. The control programis also configured to provide state information to vessel control unit.

For further explanation,sets forth a block diagram of an example of vessel control unitin accordance with at least one embodiment of the present disclosure. The example vessel control unitofincludes a CAN interfacefor coupling the vessel control unitto the CAN bus. For example, the CAN interfacemay be a network interface controller configured to send and receive messages in the form of CAN frames over the CAN bus.

The example vessel control unitalso includes a controllerthat may include or implement a processor, a microcontroller, an ASIC, PLA such as an FPGA, or other data processing unit in accordance with the present disclosure. In some examples, controlleris implemented by a processor or central processing unit configured to execute computer programming instructions, also referred to a computer executable instructions or processor executable instruction. Such instructions can be loaded from and stored in one or more memory devices collectively referred to as storage. Storagemay include EEPROM such as Flash memory (e.g., NAND and NOR flash memory or other types of solid-state memory), DRAM, SRAM, magnetic disk storage, and the like. The storagemay be integrated with the controlleror provided as a separate memory device coupled to the controller.

The vessel control unitalso includes a control programembodied in computer programing instructions stored in tangible persistent storage of storage. When executed by controller, the control programis configured to send commands to other vessel components and receive state information and diagnostic data from vessel components as discussed above.

For further explanation,sets forth a block diagram of an example electric propulsion devicefor controlling a cooling system water intake pump of an electric marine vessel in accordance with at least one embodiment of the present disclosure. In some examples, the electric propulsion deviceis an outboard motor, as depicted. However, it will be appreciated that the electric propulsion devicemay be other types of marine propulsion devices. Where the electric propulsion deviceis an outboard motor, the electric propulsion devicemay be partitioned into an upper unit, a middle unit, and a lower unit. The example electric propulsion devicemay be similar to the marine propulsion systemin. For example, the electric propulsion deviceincludes an inverterthat supplies electrical energy to an electric motor. The electric motorturns a vertical drive shaftthat is coupled via a couplerto a horizontal propeller shaftthat drives a propeller.

The electric propulsion devicealso includes a cooling system that is comprised of a water intake pumpthat pumps ambient water into cooling system via an inlet. The cooling system also includes water distribution linesthat circulate the water around the components of the electric propulsion devicesuch as the inverterand electric motor. In some examples, the cooling system may include water jackets or other structures that bring the water in the distribution linesinto thermal contact with the electric propulsion system components. The cooling system also includes one or more water temperature sensorsthat report temperature readings of the water in the distribution lines. The cooling system also includes one or more flow rate sensorsthat detect the rate of flow of the water in the distribution lines. The electric propulsion devicealso includes one or more temperature sensorslocated on or proximate to the inverterand the electric motor. The temperature sensorsmay report temperature readings of a contact surface (e.g., the electric motor casing) or ambient temperature. The electric propulsion devicealso includes a motor speed sensorconfigured to output the rotational speed of the motor. The electric propulsion devicealso includes one or more current sensors that output a reading of the electric current at various points in a power distribution system, including a current sensorthat outputs a reading of the current applied by the inverterto the electric motor. The current sensor can be, for example, a sensor in the inverter.

The electric propulsion devicealso includes a controller. The controlleris configured to receive commands from the vessel control unit and control the inverterin accordance with those commands. For example, controllermay be configured to regulate the distribution of electrical energy from the inverterto the electric motor. In this example, controllermay receive a throttle/speed command from the vessel control unit and determine the frequency variation or voltage variation that will enter the electric motor for controlling the vessel's speed. The controlleris also configured to receive TRIM commands from the vessel control unit and operate a rutter in accordance with the TRIM commands and the TRIM sensor value embedded in the outboard. The controlleris also configured to receive state information from various sensors such as the current sensor, temperature sensors,, flow rate sensor, and motor speed sensor.

The electric propulsion devicealso includes a pump controller. The pump controllermay be an electronic control unit that is separate from the electric propulsion device controller(as depicted), or may be integrated with the electric propulsion device controller. For example, the pump controllermay be a submodule of the electric propulsion device controller. The pump controllerreceives state information of the electric propulsion device, such as data from one or more of the current sensor, temperature sensors,, flow rate sensor, and motor speed sensor. The pump controllercan receive this information directly from the sensors or from other components.

In a particular example, the pump controllerreceives information describing a state of an electric propulsion device of a marine vessel, including one or more of the speed of the electric motor, the temperature of the electric motor, the temperature of the water in the cooling system, the flow rate of water in the cooling system, the temperature of the inverter, the electric current supplied by the inverterto the electric motor. In some examples, at least some of the information is collected by sensors in the electric propulsion system. In some implementations, the pump controllerreceives at least some of the information from other electronic control units, such as the vessel control unit or the electric propulsion device controller. In some examples, the pump controlleris coupled to a CAN bus for communication with other vessel components, such as the vessel control unit. In such examples, information describing the state of the electric propulsion device can be received via the CAN bus from other electronic control units.

The pump controllercan detect the motor speed of the electric motor by identifying data or values in the received information that are indicative of motor speed, such as the number of revolutions per minute of the drive shaft in the electric propulsion device. In some implementations, the pump controllercan estimate the motor speed based on the amount of current supplied to the electric motor. The pump controllercan also determine the temperature of one or more components of the electric propulsion device from the received information. For example, the pump controllermay identify data indicating the temperature of the electric motor at one or more locations on a motor casing. The pump controllermay determine the temperature of the inverter within or outside of the inverter. For example, the pump controllermay identify data indicating temperature readings from one or more temperature sensors located on, within, or proximate to the inverter.

The pump controllercontrols the water intake pumpof the cooling system for the electric propulsion device based on the information from the various sensors discussed above. In some examples, the pump controllercontrols the water intake pumpvia a signal line by increasing and decreasing the rotational speed of the pump impeller based on the motor speed of the electric motor. For example, as motor speed increases, the pump controllercan increase the pump impeller speed to meet the cooling needs of the inverter and the electric motor. As motor speed decreases, the pump controllercan decrease the pump impeller speed as less cooling is needed. When the electric motor is off, the pump controllercan continue to run the water intake pumpto continue to cool the inverter and electric motor if needed. However, if additional cooling is not needed when the electric motor is off, the pump controllercan turn the water intake pumpcompletely off. This alleviates the unwanted noise of the water intake pump when the electric marine vessel is otherwise substantially silent. In a conventional ICE system in which the pump impeller is coupled to the drive shaft, the cooling system is unable to cool the engine while the motor is off, and further the speed of the pump impeller is fixed to the rotational speed of the drive shaft and cannot be reduced.

In some examples, the rotational speed of the impeller is controlled to be less than the motor speed, i.e., less than the rotational speed of the drive shaft. Because the impeller is mechanically decoupled from the drive shaft, it need not spin at the same rate as the drive shaft if the cooling needs of the electric motor are otherwise met. By operating the impeller at a lower speed, the water intake pump produces less noise than if it were coupled to the drive shaft. As the motor speed of the electric motor increases, the pump controllercan increase the rotational speed of the impeller, either linearly or non-linearly, to compensate for the increased heat generated by the electric motor. Should the electric motor require additional cooling (e.g., based on temperature feedback information), the rotational speed of the impeller can be increased independent of the motor speed of the electric motor. Thus, the rotational speed of the impeller is adapted based on the cooling needs of the electric motor, which minimizes the noise generated by the water intake pump, rather than fixing the rotational speed of the impeller to the rotational speed of the motor.

In addition to motor speed, the temperature of the electric motor, the temperature of water in the cooling system, and the flow rate of the water in the cooling system are also indicative of the cooling needs of the electric motor. In some implementations, the pump controllercontrols the water intake pumpbased on temperature feedback data by receiving temperature feedback information from an electric motor temperature sensor, an inverter temperature sensor, a cooling system water temperature sensor, or combinations thereof. The pump controllerthen compensates the rotational speed of the impeller based on the temperature feedback information. For example, the rotational speed of the impeller may be increased in response to an increase in the motor speed of the electric motor. However, if temperature feedback information from a temperature sensor indicates that the temperature of the electric motor or inverter is too hot, the pump controllercan control the water intake pumpto increase the rotational speed of the impeller. Conversely, if the temperature feedback information from a temperature sensor indicates that the inverter or electric motor temperature is a below a temperature limit by a threshold amount, the pump controllercan control the water intake pumpto decrease the rotational speed of the impeller, thus minimizing the noise of the water intake pump. Temperature feedback information from a water temperature sensor can be used in the same way, where the temperature of the water after heat exchange with the electric motor is indicative of the electric motor temperature. Thus, based on motor speed and temperature information provided in a continuous feedback loop, the pump controllerdetermines the minimum impeller speed needed to ensure that the electric motor is sufficiently cooled, thereby minimizing the noise of the water intake pumpand extending the life of the water intake pump.

The water intake pumpis a self-priming pump. In some examples, if a flow rate sensordetects that water is not flowing in the cooling system (e.g., due to a broken impeller) with a preconfigured time period (e.g., 10 seconds), the pump controllerreports an error and discontinues operation of the pump. In some implementations, the error is reported to the electric propulsion device controller. In response to detecting that the water intake pump is non-operational, the electric propulsion device controllercan limit the motor speed of the electric motor. For example, the electric motormay be rated to run ‘dry’ (i.e., not cooled) at a particular mechanical power rating or speed rating. In such an example, the controllercontrols the electric propulsion device such that the electric motordoes not exceed this power or speed rating.

For further explanation,sets forth a flow chart of an example method for controlling a cooling system water intake pump of an electric marine vessel in accordance with at least one embodiment of the present disclosure. The example ofincludes an electric marine vessel. The electric marine vessel includes an electric propulsion device (e.g., a full-electric outboard motor) and high voltage battery packs for supplying electricity to the electric propulsion device. The electric propulsion device includes an inverter that receives power from the battery packs and converts the power into energy that is used to actuate an electric motor. The electric motor drives a propeller of the electric propulsion device via a rotating drive shaft and a coupler. The marine vesselmay include additional powertrain components as described above. During operation, the marine vessel is waterborne on a body of water (e.g., an ocean, river, lake, etc.). The inverter, electric motor and other components of the electric propulsion device are cooled via ambient water from the body of water.

The example ofincludes a pump controllerof a cooling system water intake pump. As discussed above, a water intake pumpof a cooling system in an electric propulsion device of a marine vessel draws ambient water from the body of water and circulates the water in areas proximate to the electric motor and other components. The water intake pumpincludes an impeller, the rotational speed of which is controlled by the pump controller. In some examples, the pump controlleris a standalone electronic control unit. In other examples, the pump controller may be a module that is integrated into another electronic control unit, such as controller of the marine propulsion device, a vessel control unit, and so on. In some examples, the pump controller is embodied in a set of computer programming instructions that, when executed by a processor of the pump controller, cause the processor to carry out the operations shown in.

The method ofincludes receivinginformationdescribing a state of an electric propulsion device of a marine vessel. Informationdescribing the state of the electric propulsion device can include the speed and temperature of the motor, the temperature of the water in the cooling system, the flow rate of water in the cooling system, the current drawn by the electric motor, the amount of throttle applied to the electric motor, and so on. In some examples, at least some of the informationis collected by sensors in the electric propulsion system. For example, a motor speed sensor can report the revolutions per minute (RPM) of the electric motor, while a current sensor can report the current draw of the inverter or the current supplied to the electric motor. A flow rate sensor in the cooling system can report the rate of the flow of water through the circulation lines. One or more temperature sensors can report the temperature of the inverter and/or electric motor. One or more cooling system temperature sensors can report the temperature of the water at various points in the cooling system. In some implementations, the pump controllerreceivesat least some of the informationdirectly from these sensors. In some implementations, the pump controllerreceivesat least some of the informationfrom other electronic control units, such as the vessel control unit or the electric propulsion device controller. In some examples, the pump controlleris coupled to a CAN bus for communication with other vessel components, such as the vessel control unit. In such examples, informationdescribing the state of the electric propulsion device can be received via the CAN bus from other electronic control units. In some implementations, at least part of the informationis received in one or more data messages, packets, or frames.

In some implementations, the pump controllerdetermines the motor speed of the electric motor by identifying data or values in the received informationthat are indicative of motor speed. In some implementations, the pump controllerdetermines the motor speed from the informationby identifying RPM data in the information, such as the number of revolutions per minute of the drive shaft in the electric propulsion device. In some implementations, the pump controllerdetermines the motor speed from the informationby identifying data indicating the current drawn by the inverter or electric motor that is reported by one or more electric current sensors. The motor speed can then be estimated based on the amount of current consumed. In some implementations, the pump controllerdetermines the motor speed from the informationby identifying data in the informationindicating an amount of throttle applied to the electric motor. For example, a throttle command or signal received from a vessel control unit can indicate the amount of throttle applied to the electric motor.

In some implementations, the pump controllerdetermines the temperature of one or more components of the electric propulsion device by identifying data or values in the received informationthat are indicative of the temperature of various components. For example, the pump controllermay determine the temperature of the electric motor at one or more locations on a motor casing. The informationmay indicate temperature readings from one or more temperature sensors located on or proximate to the motor casing. In another example, the pump controllermay determine the temperature of the inverter within or outside of the inverter. For example, the information may indicate temperature readings from one or more temperature sensors located on, within, or proximate to the inverter.

The method ofalso includes controlling, based on the information, the water intake pumpof the cooling system for the electric propulsion device. In some examples, the pump controllercontrolsthe water intake pumpby increasing and decreasing the rotational speed of the pump impeller based on the motor speed of the electric motor. For example, as motor speed increases, the pump controllercan increase the pump impeller speed to meet the cooling needs of the inverter and the electric motor. As motor speed decreases, the pump controllercan decrease the pump impeller speed as less cooling is needed. When the electric motor is off, the pump controllercan continue to run the water intake pumpto continue to cool the inverter and electric motor if needed. However, if additional cooling is not needed when the electric motor is off, the pump controllercan turn the water intake pumpcompletely off. This alleviates the unwanted noise of the water intake pump when the electric marine vessel is otherwise substantially silent. In a conventional ICE system in which the pump impeller is coupled to the drive shaft, the cooling system is unable to cool the engine while the engine is off and conversely the speed of the pump impeller is fixed to the rotational speed of the drive shaft and cannot be reduced.

In some examples, the rotational speed of the impeller is controlled to be less than the motor speed, i.e., less than the rotational speed of the drive shaft. Because the impeller is mechanically decoupled from the drive shaft, it need not spin at the same rate as the drive shaft if the cooling needs of the electric motor are otherwise met. By operating the impeller at a lower speed, the water intake pump produces less noise than if it were coupled to the drive shaft. As the motor speed of the electric motor increases, the pump controllercan increase the rotational speed of the impeller, either linearly or non-linearly, to compensate for the increased heat generated by the electric motor. Should the electric motor require additional cooling (e.g., based on temperature feedback information), the rotational speed of the impeller can be increased independent of the motor speed of the electric motor. Thus, the rotational speed of the impeller is adapted based on the cooling needs of the electric motor, which minimizes the noise generated by the water intake pump, rather than fixing the rotational speed of the impeller to the rotational speed of the motor.

In addition to motor speed, the temperature of the electric motor, the temperature of water in the cooling system, and the flow rate of the water in the cooling system are also indicative of the cooling needs of the electric motor. In some implementations, the pump controllercontrolsthe water intake pumpbased on temperature feedback data by receiving temperature feedback information from an electric motor temperature sensor, an inverter temperature sensor, a cooling system water temperature sensor, or combinations thereof. The pump controllerthen compensates the rotational speed of the impeller based on the temperature feedback information. For example, the rotational speed of the impeller may be increased in response to an increase in the motor speed of the electric motor. However, if temperature feedback information from a temperature sensor indicates that the temperature of the electric motor or inverter is too hot, the pump controllercan control the water intake pumpto increase the rotational speed of the impeller. Conversely, if the temperature feedback information from a temperature sensor indicates that the inverter or electric motor temperature is a below a temperature limit by a threshold amount, the pump controllercan control the water intake pumpto decrease the rotational speed of the impeller, thus minimizing the noise of the water intake pump. Temperature feedback information from a water temperature sensor can be used in the same way, where the temperature of the water after heat exchange with the electric motor is indicative of the electric motor temperature. Thus, based on motor speed and temperature information provided in a continuous feedback loop, the pump controllerdetermines the minimum impeller speed needed to ensure that the electric motor is sufficiently cooled, thereby minimizing the noise of the water intake pumpand extending the life of the water intake pump.

It will therefore be appreciated that mechanically decoupling the water intake pump from the drive shaft and providing independent control of the water intake pump via a pump controller enhances the electric boating experience by alleviating the noise of the water intake pump. Further, providing independent control of the water intake pump via a pump controller extends the life of the pump by discontinuing the pump when no mechanical power is being supplied by the electric motor.

For further explanation,sets forth a flow chart of another example method of controlling a cooling system water intake pump of an electric marine vessel in accordance with at least one embodiment of the present disclosure. The example method ofextends the method ofin that the method ofincludes detectingan operational state of the water intake pump. In some examples, the pump controllerdetectsan operational state of the water intake pumpbased on the rotational speed of the impeller and/or a reading from a flow rate sensor in the distribution lines of the cooling system. For example, the operational state of the water intake pumpmay be that the water intake pump, and more particularly the impeller, is not operating. As another example, the operational state of the water intake pumpmay be that the impeller is rotating at a maximum speed and thus cannot provide additional cooling capability. The pump controllerindicates the operational state of the water intake pump to an electronic control unit such as the vessel control unit or an electric propulsion device controller.

The method ofalso includes controllingthe electric motor based on an operational state of the water intake pump. In some examples, the electronic control unitcontrolsthe electric motor in response to detecting an operational state of the water intake pump. For example, in response to identifying that the water intake pumpis not operating, the electronic control unitlimits the motor speed of the electric motor. For example, the electric motor may be rated to run ‘dry’ (i.e., not cooled) at a particular mechanical power rating. In such an example, the electronic control unit controls the electric propulsion device such that the electric motor does not exceed this power rating. In another example, in response to detecting that the water intake pumpis operating at a maximum capability, the electronic control unit may limit the motor speed of the electric motor.