Electric water heating system

Abstract

In a first aspect of the present invention there is provided an electric water heating system. The electric water heating system comprises a fluid-cooled battery pack comprising at least one battery cell and at least one battery cooling duct thermally coupled to the at least 5 one battery cell. The electric water heating system further comprises an electrical water heating device electrically coupled to the at least one battery cell. The electric water heating system further comprises a plurality of power electronics components located above the fluid-cooled battery pack. The power electronics components are electrically coupled to the at least one battery cell. The electric water heating system further comprises 10 a power component cooler for cooling the power electronics components. The power component cooler defines at least part of a power cooling duct that is thermally coupled to the power electronics components and fluidly coupled to the battery cooling duct such that, in use, a heat exchange fluid flows through both the battery cooling duct and the power cooling duct

Description

[0001] Summary

[0002] In a first aspect of the present invention there is provided an electric water heating system. The electric water heating system comprises a fluid-cooled battery pack comprising at least one battery cell and at least one battery cooling duct thermally coupled to the at least one battery cell. The electric water heating system further comprises an electrical water heating device electrically coupled to the at least one battery cell. The electric water heating system further comprises a plurality of power electronics components located above the fluid-cooled battery pack. The power electronics components are electrically coupled to the at least one battery cell. The electric water heating system further comprises a power component cooler for cooling the power electronics components. The power component cooler defines at least part of a power cooling duct that is thermally coupled to the power electronics components and fluidly coupled to the battery cooling duct such that, in use, a heat exchange fluid flows through both the battery cooling duct and the power cooling duct.

[0003] The electric water heating system is therefore configured to cool both the battery cell(s) and the power electronics components simultaneously by removing thermal energy from the at least one battery cell and the power electronics components. For example, the power cooling duct may function as a heat sink for the power electronics components, and the battery cooling duct may function as a heat sink for the battery cell(s). In particular, the power cooling duct and the battery cooling duct are configured such that a heat exchange fluid may flow through both the battery cooling duct and the power cooling duct to receive thermal energy from the battery cell(s) and the power electronics components, in use.

[0004] The power electronics components and the battery cell(s) may be indirectly thermally coupled via the fluidly coupled power cooling duct and battery cooling duct, and in particular by the heat exchange fluid flowing through the ducts, in use.

[0005] In some examples, the power electronics components may be operated to charge the at least one battery cell. In some examples, such charging may occur when the electrical water heating device is not active, such that the battery cell(s) is / are not being discharged to power the electrical water heating device whilst the cell(s) is / are being charged.

[0006] In some examples, the electric water heating system may be configured to store heat generated by the power electronics components in the at least one battery cell. The battery cell(s) may receive thermal energy from the power electronics components via the heat exchange fluid flowing through the power cooling duct and the battery cooling duct. Forexample, the power electronics components may produce thermal energy when charging the at least one battery cell, and such thermal energy may be removed from the power electronics components by the power component cooler, in particular by the heat exchange fluid in the power cooling duct. The heated heat exchange fluid may then be flowed through the battery cooling duct such that the battery cell(s) receives thermal energy from the heated heat exchange fluid in the battery cooling duct. The battery cell(s) may therefore provide a thermal mass for storing thermal energy produced by the power electronics components. As described below in more detail in some examples the thermal energy stored in the battery cell(s) may be used to pre-heat a flow of incoming water to be heated by the electrical water heating device, thereby improving the efficiency of the electric water heating system.

[0007] The electric water heating system may be considered to include a thermal energy recovery system which comprises the power cooling duct and the battery cooling duct. The thermal energy, i.e. heat, produced by the battery cell(s) and the power electronics components during charging and discharging of the battery may be recovered by the thermal energy recovery system, namely by heat exchange fluid in the power cooling duct and battery cooling duct, for subsequent use in another application. For example, the recovered thermal energy may be used for pre-heating a flow of incoming water to be heated by the electrical water heating device, in some examples, as described in more detail below. Notably, the electric water heating system is specifically configured to capture, i.e. recover, heat from the power electronics components and the battery cell(s) to be used or reused for a specific purpose, such that the thermal energy is not simply wasted or emitted for the single purpose of cooling the power electronics components and the battery cell(s). In some examples the thermal energy recovery system may include the at least one battery cell. As described previously, the battery cell(s) may provide a thermal mass for storing heat recovered from the power electronics components. Such heat stored in the battery cell(s) may be used for pre-heating a flow of incoming water to be heated by the electrical water heating device, in some examples, as described in more detail below. The battery cell(s) may also store thermal energy produced by the battery cell(s) during charging and / or discharging of the cell(s).

[0008] The term “thermally coupled” should be understood to refer to the facility for transferring heat between two components. Conversely, for context, if a component is thermally insulated it is not thermally coupled to another component. For example, such a thermally insulated component may be separated from another component by a thermally insulating material. Air is a poor conductor of heat and may therefore be considered to be a thermalinsulator, such that an air gap between components may thermally decouple such components. In preferred examples, thermally coupled may therefore mean that the respective thermally coupled components are configured such that, in use, heat may be transferred between the components by physical contact, i.e. by conduction.

[0009] Relative terms such as above and below refer to the relative positions of components or features when the electric water heating system is oriented in an installed and ready to use configuration.

[0010] Arranging the power electronics components above the fluid cooled battery pack advantageously facilitates additional heat capture from the battery pack. Whilst the battery pack comprises a battery cooling duct thermally coupled to the at least one battery cell to recover heat produced by the battery cell(s) and thereby cool the battery cell(s), some excess battery heat may not be recovered by the battery cooling duct. Such excess battery heat may rise. Accordingly, power electronics components located above the fluid-cooled battery pack may receive such excess battery heat. With the power electronics components thermally coupled to the power cooling duct, the excess battery heat may be recovered in the power cooling duct, via the power electronics components. The power electronics are therefore located above the fluid cooled battery pack to capture excess heat produced by the battery cell(s).

[0011] Arranging the power electronics components above the fluid cooled battery pack also reduces the risk of damage to the power electronics components if a heat exchange fluid leakage occurs in the fluid cooled battery pack. The specific configuration of the electric water heating system advantageously includes a thermal energy recovery system for recovering heat from the battery cell(s) and the power electronics components whilst minimising the risk of damage to the power electronics components resulting from the specific inclusion of the thermal energy recovery system. Accordingly, the electric water heating system described herein provides an energy efficient, reliable, and safe means for heating water using electricity.

[0012] In some examples, the electric water heating system may comprise a plurality of battery cells. In preferred examples, the at least one battery cooling duct may be thermally coupled to the plurality of battery cells. The electrical water heating device may be electrically coupled to the plurality of battery cells. The plurality of power electronics components may be electrically coupled to the plurality of battery cells. The plurality of battery cells mayprovide a thermal mass for storing thermal energy produced by the power electronics components and / or the cells themselves, as described previously.

[0013] The plurality of battery cells may be arranged in a vertically stacked configuration. For example, the battery cells may be mounted in a rack or cell housing(s) to retain the battery cells in a vertically-stacked configuration, in some examples. Vertically-stacked refers to the cells being adjacent to one another in a vertical direction, when the electric water heating system is oriented in an installed and ready to use configuration. The power electronics components may be considered to be located vertically above the battery pack, i.e. vertically above the plurality of vertically stacked cells, in some examples.

[0014] In some examples, the battery pack may comprise a plurality of battery modules. Each battery module may comprise a cell housing which houses at least one battery cell and a module duct which defines part of the battery cooling duct. Accordingly, the battery pack may comprise a plurality of battery cells, and each cell may be located in a cell housing of a battery module. Locating the battery cells in cell housings may be advantageous for improving the capture of heat produced by the battery cells. Further, the use of battery modules may simplify assembly of the electric water heating system because individual battery modules can be assembled separately offline before the modules are arranged together to assemble the battery pack. Additionally, the cell housings may help to protect cells in the battery pack, both during assembly and in use.

[0015] The fluid cooled battery pack may comprise a plurality of battery modules arranged in a stacked configuration. Each battery module may comprise a plurality of battery cells. In other words, a plurality of battery cells may be housed in each battery module. In some examples, each cell housing may define at least one cell compartment and the module duct may be thermally coupled to the at least one cell compartment. In some examples, the cell housings may each define a plurality of cell compartments. A cell housing defining a plurality of cell compartments may advantageously facilitate thermal management of a plurality of cells in a compact, space-efficient configuration. Thermally coupling the cell compartment(s) and module duct facilitates the transfer of thermal energy, i.e. heat, between the cell compartment(s) and the module duct of the respective battery module.

[0016] In some examples, each battery cell may be bonded into the cell compartment in which it is located. Accordingly, each cell compartment may comprise adhesive for bonding a cell to the cell housing. Each cell compartment may comprise one or more internal surfaces. In some preferred examples, each cell may be bonded to each internal surface of the cellcompartment in which the cell is located. For example, the battery module may comprise a layer of adhesive between each cell and the respective cell compartment in which the cell is located. In some preferred examples, the adhesive layer may be substantially continuous, i.e. unbroken and free of voids, between the cell and a respective internal surface of the cell compartment. More preferably still, in some examples the cell may be surrounded by a substantially continuous layer of adhesive. A substantially continuous layer of adhesive provides an advantageous thermal bridge between the respective cell and the cell housing for transferring heat to the module duct in use.

[0017] In some preferred examples, the adhesive may have a thermal conductivity greater than 0.2 W / mK, more preferably greater than 0.3 W / mK, and more preferably still greater than 0.4 W / mK. As such, the adhesive is preferably thermally conductive to facilitate heat transfer from the or each cell to the respective cell compartment and module duct. Further, in some preferred examples, the adhesive may be electrically insulating. The adhesive may be an epoxy-based, or silicone-based adhesive, in some examples. An example of a suitable adhesive may be Momentive ® RTV627, which has a thermal conductivity of 0.31W / mk.

[0018] In some preferred examples, the module duct of each battery module may extend substantially horizontally. Horizontally-oriented module ducts may be advantageous for minimising the risk of trapping air, i.e. air bubbles, in the battery cooling duct, which could reduce the efficiency with which heat is transferred away from the cell compartment(s) and associated cell(s), in use.

[0019] Further, in some examples, each cell housing and the cell compartment(s) defined by the cell housing may be elongated in the horizontal direction. In particular, in some examples the cell compartment(s) may extend longitudinally in a compartment direction, along a cell compartment axis. Accordingly, the cell housing may be configured such that the cell compartment axis is substantially horizontal, in use. As such, a module duct extending horizontally along a cell compartment may advantageously present a large surface area for transferring heat from the respective cell compartment to a heat exchange fluid in the module duct, in use.

[0020] In some preferred examples, a “substantially horizontally” extending module duct may be inclined at less than + / - 2 degrees from horizontal (0 degrees), or more preferably still at less than + / - 1 degrees from horizontal, in use. Orienting the module ducts in this range and / or orienting the battery pack such that the module ducts extend in this range isparticularly advantageous for minimising the risk of trapping air in the module ducts. It will be appreciated that inclination of a module duct preferably refers to an angle defined between a horizontal line (i.e. 0 degrees) and a longitudinal axis of the module duct. Most preferably the module duct may not be inclined relative to horizontal, i.e. the module duct may be inclined at 0 degrees from horizontal, in use.

[0021] In some examples, the battery cooling duct may be defined in part by one or more duct connectors. Each duct connector may be sealed to at least one of an inlet and / or an outlet of a respective module duct at a seal interface to fluidly couple the module ducts of adjacent battery modules. Each seal interface is preferably located below the power electronics components, in preferred examples. Below is opposite of above, for example, the power electronics components are located above the battery pack and therefore also above the sealing interfaces. Above and below may be defined in relation to the vertical stacked arrangement of the cells of the battery pack, in some examples. Configuring the electric water heating system such that the seal interfaces are located below the power electronics components further improves safety by minimising the risk of fluid damage or short circuits in the unlikely event of a heat exchange fluid leakage at the seal interfaces.

[0022] In some preferred examples, each module duct may be substantially U-shaped. For example, the inlet and outlet of each module duct may be located on the same side of a respective battery module. Accordingly, each module duct may comprise a first portion configured to flow heat exchange fluid in a first direction from the inlet and a second portion configured to flow the fluid to the outlet in a second direction that is substantially opposite to the first direction. A U-shaped module duct may be particularly advantageous for transferring heat away from the cell compartment(s) in use because a U-shaped module duct presents a large surface area for conducting heat from the respective cell compartment to the heat exchange fluid in the module duct. A U-shaped module duct may also help to distribute the cooling effect more evenly along the cell compartment.

[0023] In some preferred examples, the plurality of battery modules may be arranged in the same orientation relative to one another. In examples where the modules ducts are substantially u-shaped, all inlets and outlets of the module ducts may therefore be arranged on the same side of the battery pack. Accordingly, the module ducts of the adjacently stacked cell housings may all be fluidly coupled at the same side of the battery pack. Advantageously in such a configuration all sealing interfaces in the battery pack may be located on the same side of the battery pack. This may be beneficial for assembly and maintenance of the battery pack. Each cell housing may therefore comprise a connection end at which theduct connector is attached, and each cell housing may be arranged with its respective connection end on the same side of the battery pack.

[0024] The battery pack may comprise a plurality of battery modules stacked on top of one another. In some examples, the battery cooling duct may have a substantially serpentine configuration. For example, the module ducts and the or each duct connector may together define a serpentine flow path through a plurality of adjacently stacked battery modules. Accordingly, the battery pack may be configured such that the battery cooling duct defines an in-series flow path flowing through a module duct, through a duct connector and subsequently through a module duct of an adjacent stacked battery module, after one another in series. Such a configuration may be advantageous for cooling performance in use, and for ease of manufacture.

[0025] In some examples, a plurality of the cooling duct connectors may be defined by a connection manifold. In some preferred examples the connection manifold may define all of the duct connectors fluidly coupling all of the module ducts of battery modules in the battery pack. Such an example may reduce part count and simplify assembly of the electric water heating system.

[0026] In some examples, the connection manifold may be configured such that when it is not yet attached to and sealed to the battery modules, each duct connector defined by the connection manifold may be fluidly isolated from other duct connectors defined by the connection manifold. Accordingly, fluid communication between the duct connectors may only be facilitated via the module ducts of the battery modules. Such a configuration may result in a battery cooling duct that directs a flow of heat exchange fluid through the module ducts of each stacked battery module in series, as described previously. The connection manifold, and in particular the duct connectors defined by the connection manifold, may, together with the module ducts, define a battery cooling duct having a serpentine configuration. This configuration provides a multitude of exchanges of heat exchange fluid between the battery modules and the connection manifold whilst minimising the number of individual components because a single connection manifold fluidly couples the module ducts of multiple pairs of adjacent battery modules. Alternatively, in some other examples the electric water heating system may comprise a plurality of connection manifolds, whereby each connection manifold defines a respective plurality of duct connectors.

[0027] In some examples, the connection manifold may additionally define at least part of the power cooling duct. Such a configuration may advantageously reduce part count andreduce the number of interfaces that need to be sealed to prevent leakage of heat exchange fluid from the battery cooling duct and power cooling duct.

[0028] In some examples, the connection manifold may define at least part of the power component cooler. For example, the power component cooler may be integrally formed with the connection manifold, in some examples. The connection manifold may therefore define the plurality of duct connectors and at least part of the power cooling duct, in some examples. The power component cooler and the plurality of duct connectors may be defined by a single unitary component, in some examples. In other words, the power component cooler and the connection manifold may be different parts or portions of a single, integrated component. For example, the power component cooler and the plurality of duct connectors may be formed as a single component, for example by machining the connection manifold from a single billet of material, casting, or moulding. Again, such a configuration may advantageously reduce part count and therefore reduce the number of assembly steps required to assemble the electric water heating system.

[0029] In some other examples, the power component cooler and the connection manifold may be separate components. The power component cooler and the connection manifold may be connected to one another such that the power cooling duct and battery cooling duct are fluidly coupled. For example, the power component cooler and the connection manifold may be attached to one another directly, or indirectly via another component. The power component cooler and the connection manifold may be sealed to one another in some preferred examples. In some examples the power component cooler and the connection manifold may be removably attached to one another.

[0030] In some examples, the electric water heating system may further comprise a cooling plate thermally coupled to the power cooling duct. The power electronics components may be attached to the cooling plate and thermally coupled to the cooling plate. Attaching the power electronics components to the cooling plate may provide thermal coupling for conducting heat from the power electronics components to the cooling plate. The cooling plate may provide an increased surface area for receiving heat from the power electronics components and subsequently conducting the heat away from the power electronics components. Attaching the power electronics components to a cooling plate may also be advantageous for simplifying assembly of the electric water heating system.

[0031] The cooling plate may be considered to function as a heat sink. The cooling plate may be described as a heat dissipation plate, or a heat exchange plate. The cooling plate isspecifically configured to transfer heat away from the power electronics components, for example to a heat exchange fluid in the power cooling duct. As such, the cooling plate is preferably formed of a heat conducting material. For example, the cooling plate may comprise copper, or aluminium, in some examples, for advantageous conduction and heat transfer.

[0032] In some examples, the cooling plate may be formed integrally with the power component cooler. For example, the cooling plate may be a side portion of the power component cooler. As described previously, in some examples, the power component cooler may be formed integrally with a connection manifold. It follows that in some examples, the connection manifold may therefore define both the power component cooler and the cooling plate, as well as the plurality of duct connectors. In some examples, the power component cooler, the cooling plate, and the plurality of duct connectors may therefore all be defined by a unitary component, namely the previously-described connection manifold. Such a configuration reduces part count and assembly complexity, as well as reducing the number of interfaces that require sealing.

[0033] In some examples, the power cooling duct may be defined in part by the cooling plate. Accordingly, the cooling plate may be directly thermally coupled to the power cooling duct, and to the flow of heat exchange fluid in the power cooling duct, in use. For example, the cooling plate may be defined by a side portion of the power component cooler which also defines at least part of the power cooling duct. Accordingly, the electric water heating system may be configured such that in use, the heat exchange fluid in the power cooling duct flows directly over a surface of the cooling plate, such as a back surface, and the power electronics components may be attached to an opposing surface of the cooling plate, such as a front surface. Such a configuration may be advantageous for minimising the distance between the power electronics components and the heat exchange fluid in the power cooling duct for faster heat transfer away from the power electronics components.

[0034] In some examples the cooling plate may be removably attached to the power component cooler. For example, the cooling plate and at least part of the power cooling duct may be defined by a removable part of the power component cooler.

[0035] In some examples, the power cooling duct may be defined in part by a side portion of the power component cooler, and the cooling plate may be attached and thermally coupled to the side portion. Accordingly, the cooling plate may be a separate component which isattached to the power component cooler. As such, the cooling plate may be indirectly thermally coupled to the power cooling duct, and to the flow of heat exchange fluid in the power cooling duct, via the side portion of the power component cooler, in use. Such a configuration may facilitate simplified assembly of the electric water heating system. For example such a configuration may facilitate a modular assembly process whereby the power electronics components are pre-assembled with the cooling plate. For example the power electronics components may each be attached to the cooling plate before the cooling plate, with power electronics components attached, is subsequently attached to the power component cooler. This may simplify the attachment and thermal coupling of the plurality of power electronics components. This may also offer improved access to the power electronics components for electrical coupling during assembly, because such electrical coupling of the plurality of power electronics components may be done in a pre¬ assembly step, before the assembled cooling plate and attached power electronics components are arranged with the rest of the electric water heating system.

[0036] In some examples, the side portion of the power component cooler may be removable from a main body of the power component cooler. The cooling plate may be attached and thermally coupled to the removable side portion. Accordingly, the cooling plate may be indirectly thermally coupled to the power cooling duct, and to the flow of heat exchange fluid in the power cooling duct, via the removable side portion, in use. Such a configuration may also facilitate simplified assembly of the electric water heating system. Additionally, such a configuration including a removable side portion may provide access to the power cooling duct following assembly, for example for maintenance operations. For example, the power cooling duct may be accessed by removing the side portion and the cooling plate with the power electronics components attached, without requiring disassembly and separate decoupling of all power electronics components. The removable side portion may therefore be referred to as a removable access cover of the power component cooler, in some examples. In some examples the cooling plate may be removably attached to the removable side portion of the power component cooler. Again, such a configuration may be advantageous for assembly and maintenance of the electric water heating system.

[0037] In some examples, the power electronics components may be attached to a substantially vertically-extending attachment surface of the cooling plate. For example, the cooling plate may be described as extending substantially vertically and / or being oriented vertically. Orienting the cooling plate vertically, i.e. such that the surface to which the power electronics components are attached extends substantially vertically, may be advantageous for packaging the power electronics components in a small footprint. Thismay be beneficial for reducing the overall footprint of the electric water heating system such that it can fit within the same operating envelope as a typical domestic gas powered boiler.

[0038] In some other examples, the cooling plate may be oriented such that the attachment surface to which the power electronics components are attached extends substantially horizontally. A substantially horizontally extending cooling plate may offer increased efficiency in the capture of rising excess heat produced by the battery cell(s). In some examples, the electric water heating system may therefore comprise a cooling plate located between the battery pack and the power electronics components. In other words the cooling plate may be substantially sandwiched between the battery pack and the power electronics components, in some examples. In some such examples, at least part of the power cooling duct may also be located between, i.e. sandwiched between, the battery pack and the power electronics components.

[0039] In some examples, the power cooling duct may comprise a serpentine flow path. A serpentine path as used herein is a configuration in which the duct is at least U-shaped. At least U-shaped means that the duct has at least a first portion configured to flow fluid in a first direction, a corner portion to redirect the fluid flow, and at least a second portion configured to flow fluid in a second direction substantially opposite to the first direction. In some preferred examples, a serpentine path may refer to a configuration in which the duct additionally includes at least a second corner portion to redirect the fluid flow and at least a third portion configured to flow fluid in a third direction which is substantially opposite to one of the first or second direction, and substantially the same direction as the other of the first or second direction. For example, such a serpentine path may be substantially S- shaped. A serpentine path provides an increased surface area of the respective duct for receiving heat.

[0040] In some examples, one or more baffles or separating ribs may be formed in the power component cooler to define the serpentine power cooling duct. Such a baffle or separating rib may extend from the side portion of the power component cooler. In some examples, a baffle or separating rib may extend from the removable side portion. In some examples where the cooling plate is defined by the power component cooler, such as by the side portion, a baffle or separating rib may be defined by the same portion of the power component cooler that defines the cooling plate. As described previously, in some examples the power component cooler may be formed integrally with the connectionmanifold, and a baffle or separating rib may therefore also be integrally formed with the connection manifold in some examples.

[0041] The power electronics components may comprise at least an AC to DC converter, i.e. an alternating current (AC) to direct current (DC) converter. The AC to DC converter is preferably configured to receive AC electricity, convert the AC electricity to DC electricity, and output the resultant DC electricity. For example, the AC to DC converter may be configured to output the resultant DC electricity to at least one battery cell.

[0042] In some examples, the power electronics components may comprise an AC to DC isolation transformer. In some examples, the power electronics components may include electronic power switching devices such as Insulated-gate bipolar transistors (IGBTs) and / or field¬ effect transistors (FETs), in some examples. For example, the electric water heating system may comprise one or more IGBTs and / or one or more FETs electrically coupled to the at least one battery cell. Further, the electric water heating system may comprise one or more IGBTs and / or one or more FETs thermally coupled to the power cooling duct, in some examples. In some examples, the power electronics components may include one or more resistors. For example, the power electronics components may include a snubber resistor. The or each resistor is preferably thermally coupled to the power cooling duct.

[0043] In some examples, the AC to DC isolation transformer may be housed in a heat conductive housing which is thermally coupled to the power cooling duct. For example, the heat conductive housing may comprise an aluminium housing. In some examples, the heat conductive housing may be attached and thermally coupled to the side portion of the power component cooler, which may be a removable side portion in some examples. Additionally or alternatively, in some examples, the heat conductive housing may be attached and thermally coupled to the cooling plate.

[0044] In some examples, the isolation transformer may be surrounded by a thermally conductive adhesive potting compound bonding the isolation transformer to an interior of the heat conductive housing. For example, the isolation transformer may be surrounded by a layer of adhesive between the isolation transformer and the heat conductive housing. In some preferred examples, the adhesive layer may be substantially continuous, i.e. unbroken and free of voids, between the isolation transformer and the interior of the heat conductive housing. A substantially continuous layer of adhesive provides an advantageous thermal bridge between the isolation transformer and the heat conductive housing, in use.In some preferred examples, the adhesive potting compound may have a thermal conductivity greater than 0.2 W / mK, more preferably greater than 0.3 W / mK, and more preferably still greater than 0.4 W / mK. As such, the adhesive is preferably thermally conductive to facilitate heat transfer from the isolation transformer to the heat conductive housing. Further, in some preferred examples, the adhesive may be electrically insulating. The adhesive may be an epoxy-based, or silicone-based adhesive, in some examples. An example of a suitable adhesive may be Momentive ® RTV627, which has a thermal conductivity of 0.31 W / mk.

[0045] The adhesive may be referred to as a potting compound in some examples. The adhesive may advantageously accommodate production tolerances in both the isolation transformer and the heat conductive housing. For example, during manufacture the adhesive introduced to the interior of the heat conductive housing may have a viscosity of less than 25 pascal seconds (Pa.s). Such an adhesive may advantageously spread thoroughly throughout the interior of the housing, forming a continuous layer that provides a thermal bridge which is advantageous for heat transfer. In some particularly preferred examples, the adhesive may have a viscosity of less than 5 pascal seconds (Pa.s) to ensure that the adhesive flows throughout the interior of the housing during assembly. By way of example, a particularly advantageous adhesive, such as Momentive ® RTV627, may have a viscosity of less than 1.5 pascal seconds (Pa.s). In some preferred examples, the adhesive, when set to bond the isolation transformer into the heat conductive housing, may be somewhat flexible or compliant, i.e. not rigid, such that the adhesive layer may accommodate thermal expansion and contraction of the isolation transformer and / or housing, in use.

[0046] In some examples, the electrical water heating device may comprise a water inlet configured to receive a flow of incoming water and a water outlet configured to discharge heated water. The power electronics components may be thermally coupled to the flow of incoming water at the water inlet via the power cooling duct. For the avoidance of doubt, the electric heating device is preferably configured to apply heat to the incoming flow of water between the water inlet and the water outlet, to increase the temperature of the flow of water. The electrical water heating device may comprise one or more electrically resistive heating elements in some preferred examples.

[0047] In some examples, the electric water heating system may further comprise a heat exchanger fluidly coupled to the power cooling duct such that the power electronics components are thermally coupled to the flow of incoming water via the power cooling ductand the heat exchanger. In some examples, the electric water heating system may therefore be configured such that the heat exchanger is operable to pre-heat the incoming flow of water using heat recovered from the battery cells and the power electronics components. In examples comprising a heat exchanger, the power cooling duct may be indirectly thermally coupled to the flow of incoming water via the heat exchanger. It follows that the power electronics components may be indirectly thermally coupled to the flow of incoming water at the water inlet via the power cooling duct and the heat exchanger, in some examples.

[0048] In some examples, the power component cooler may define a power cooling duct outlet that is fluidly coupled to the heat exchanger. Accordingly, the heat exchanger may be fluidly coupled to the power cooling duct downstream of the power cooling duct. The electric water heating system may therefore be configured such that the heat exchanger receives heat exchange fluid from the power component cooler which has been heated by heat from the power electronics components.

[0049] In some examples, the power cooling duct may be fluidly coupled to the water inlet of the electrical water heating device. For example, the water inlet of the electrical water heating device may be fluidly coupled to the power cooling duct downstream of the power cooling duct. For example, the electric water heating system may be configured such that water may flow through the battery cooling duct and power cooling duct before entering the electric heating device at the water inlet. The incoming flow of water may therefore be directly pre-heated in the battery cooling duct and the power cooling duct before delivery to the electrical water heating device at the water inlet. It follows that the power component cooler may define a power cooling duct outlet that is fluidly coupled to the water inlet of the electrical water heating device, in some examples. In some examples, the heat exchange fluid may therefore be the incoming flow of water to be heated by the electrical heating device and subsequently supplied to a respective outlet.

[0050] In some examples, the power component cooler may define a power cooling duct inlet that is fluidly coupled to the battery cooling duct and configured to receive a flow of heat exchange fluid from the battery cooling duct. Accordingly, the power cooling duct may be arranged downstream of the battery cooling duct. The flow of heat exchange fluid may therefore be heated first in the battery cooling duct by heat originating from the battery cells, before being heated further in the power cooling duct by heat provided from the power electronics components. Such an arrangement may be advantageous because the power electronics components may be expected to produce more thermal energy, i.e.heat, than the battery cell(s). Arranging the power cooling duct downstream of the battery cooling duct therefore ensures that heat exchange fluid supplied to the battery cooling duct is not pre-heated by the power electronics components. This may help to ensure that the heat exchange fluid is at a lower temperature than the battery cell(s) when initially supplied to the battery cooling duct such that the heat exchange fluid can absorb the heat produced by the battery cell(s). Similarly, in such a configuration heat exchange fluid pre-heated in the battery cooling duct by the battery cell(s) may be expected to still have a lower temperature than the power electronics components, such that the pre-heated heat exchange fluid supplied to the power cooling duct is at a lower temperature than the power electronics components. Accordingly the heat exchange fluid can then additionally absorb the heat produced by the power electronics components in the power cooling duct.

[0051] In some examples where the water heating system comprises a heat exchanger, the heat exchanger may be fluidly coupled the power cooling duct inlet via the battery cooling duct. Heat exchange fluid may therefore be delivered back to the battery cooling duct after heat has been removed from the heat exchange fluid by the heat exchanger. As described previously, the flow of heat exchange fluid may then flow through the battery cooling duct before subsequently being received by the power cooling duct.

[0052] Brief description of the drawings

[0053] Examples of the present invention will now be described by way of non-limiting example only, with reference to the accompanying figures, in which:

[0054] Figure 1 is a schematic perspective rear view of an electric water heating system comprising a fluid-cooled battery pack and a power component cooler;

[0055] Figure 2 is a schematic cross-sectional view through the electric water heating system in a rear plane of the fluid-cooled battery pack;

[0056] Figure 3 is a schematic cross sectional view through the electric water heating system in a side plane through a battery cooling duct of the fluid-cooled battery pack;

[0057] Figure 4 is a schematic cross-sectional view in a rear plane through the power component cooler;

[0058] Figure 5 is a schematic perspective view of a plurality of power electronics components thermally coupled to the power component cooler;Figure 6 is a schematic diagram of an example of the electric water heating system; and

[0059] Figure 7 is a schematic diagram of a different example of the electric water heating system.

[0060] Detailed

[0061]

[0062] Figure 1 is a schematic perspective view of an electric water heating system 10. In use, the water heating system 10 may heat a supply of water to provide hot water for a water¬ based room heating system, or for supplying outlets such as taps and showers. An overview of the electric water heating system 10 will be described with reference primarily to Figure 1, with additional brief references to Figures 2, 3 and 4. Subsequent description of the features of the electric water heating system 10 will be provided with general reference to all of the accompanying figures.

[0063] As shown in Figure 1, the electric water heating system 10 includes a fluid-cooled battery pack 12 and an electrical water heating device 14. The electrical water heating device 14 is electrically coupled to at least one battery cell 16 in the fluid-cooled battery pack 12 such that the at least one cell 16 may power the electrical water heating device 14. The battery pack 12 may include a plurality of battery cells 16, as shown in the accompanying figures. Whilst the invention will be described with reference to examples in which the battery pack 12 comprises a plurality of battery cells 16, it should be appreciated that in all examples the battery pack 12 may simply include at least one battery cell 16.

[0064] The battery pack 12 is a fluid-cooled battery pack. Accordingly, the battery pack 12 includes at least one battery cooling duct 18 which is thermally coupled to the battery cells 16, as shown most clearly in the cross-sectional views of Figures 2, 3, 4 and 5. In use, a heat exchange fluid flows through the battery cooling duct 18 to receive heat produced by the battery cells 16, forexamplewhen charging or discharging the battery cells 16. In some other examples, a heat exchange fluid flowing in the battery cooling duct 18 may provide thermal energy, i.e. heat, to the battery cells 16 in examples where the battery cells 16 provide a thermal mass for storing thermal energy.

[0065] For charging and discharging the battery cells 16, and for general power management, the electric water heating system 10 additionally includes a plurality of power electronics components 20. For example, the power electronics components 20 may include switching devices such as insulated-gate bipolar transistors (IGBTs) or field-effect transistors (FETs). The power electronics components 20 may also include one or more resistors, such as a snubber resistor. Notably, operating the power electronics components 20 tocharge and discharge the battery cells 16 may also produce a substantial amount of heat, i.e. thermal energy, in and around the power electronics components 20. For example a snubber resistor may produce around 200 W of heat. For continued safe and reliable operation of the electric water heating system 10 it may be advantageous to cool the power electronics components 20, i.e. to remove heat from the power electronics components 20. Accordingly, the electric water heating system 10 includes a power component cooler 22.

[0066] As shown in Figure 3, the power component cooler 22 defines at least part of a power cooling duct 24 which is thermally coupled to the power electronics components 20. For example, power electronics components 20 such as IGBTs, FETs, and resistors may be thermally coupled to the power cooling duct 24. In use, a heat exchange fluid in the power cooling duct 24 receives heat produced by the power electronics components 20. The power cooling duct 24 may have a serpentine flow path, i.e. a flow path which is at least U-shaped, as shown most clearly in Figure 4. This presents a large surface area for receiving heat from the power electronics components 20, and also improves the distribution of cooling throughout the power component cooler 22.

[0067] Notably, the power cooling duct 24 defined by the power component cooler 22 is fluidly coupled to the battery cooling duct 18. As such, in use, a heat exchange fluid flows through both the battery cooling duct 18 and the fluidly coupled power cooling duct 24. For example, as shown in the cross-sectional views of Figures 3, 4 and 5, the power component cooler 22 may define a power cooling duct inlet 26a, and the inlet 26a may be fluidly coupled to the battery cooling duct 18. The power cooling duct inlet 26a may therefore be configured to receive a flow of heat exchange fluid from the battery cooling duct 18. Conversely, in some examples the heat exchange fluid may be flowed backwards, i.e. from the power cooling duct 24 into the battery cooling duct 18. In such an example the battery cells 16 may provide a thermal mass for storing heat produced by the power electronics components 20.

[0068] The examples of the electric water heating system 10 described herein provide an advantageously efficient means for heating water using electricity. For example, the electric water heating system 10 is configured to cool the battery cells 16 and power electronics components 20 to optimise performance and longevity of these components, whilst also facilitating the recovery of heat produced by these components. As described in more detail later, the recovered heat may be utilised during operation of the electrical water heating device 14, thereby improving the overall efficiency of the system 10.Notably, the electric water heating system 10 is configured to increase safety whilst also providing the efficiency and longevity improvements described above. In particular, whilst fluid-cooling the battery pack 12 improves longevity and efficiency, the inclusion of heat exchange fluid in the system 10 introduces the risk of fluid leakages which could cause short circuits between electronic components of the system 10. The power electronics components 20 may be subject to particularly high currents and voltages, and short-circuits between such components could be particularly detrimental. The electric water heating system 10 is therefore specifically configured with the power electronics components 20 located above the fluid-cooled battery pack 12 to minimise the risk of damage and fluid- related short-circuits in the power electronics components 20. The configuration of the electric water heating system 10 therefore improves reliability by reducing the risk of damage to components of the system 10 in the unlikely event of a fluid leakage.

[0069] Examples of various features of the electric water heating system 10 will now be described in more detail with general reference to all of the accompanying figures.

[0070] For example, with particular reference to Figures 1 and 2, the battery pack 12 may include a plurality of battery modules 28. As shown, the modules 28 may be arranged on top of one another in a stacked arrangement, in some examples. Each battery module 28 may include a cell housing 30 which houses at least one battery cell 16. As previously described the fluid-cooled battery pack 12 comprises a battery cooling duct 18 to which the or each battery cell 16 is thermally coupled. In some examples, part of the battery cooling duct 18 may be defined by a module duct 32 of each battery module 28. For example, as shown in the accompanying figures, the cell housing 30 may define the module duct 32, in some examples.

[0071] The module ducts 32 of adjacent battery modules 28 may be fluidly coupled by respective duct connectors 34 to form the battery cooling duct 18. For example, each duct connector 34 may be sealed to an inlet 36a or an outlet 36b of a respective module duct 32 at a seal interface 38. As shown in the accompanying figures, in some examples the duct connectors 34 may be defined by a connection manifold 40. This means that a plurality of module ducts 32 can be connected in the same assembly step to form the battery cooling duct 18 by connecting the connection manifold 40 to a plurality of battery modules 28. This is shown most clearly in the cross-sectional views of Figures 3 and 5, and the schematic diagrams in Figures 6 and 7.In some examples, part of the power cooling duct 24 may be defined by the connection manifold 40. For example, the connection manifold 40 may define at least part of the power component cooler 22. In other words, the connection manifold 40 and at least part of the power component cooler 22 may be formed integrally with one another, for example by machining the combined components from the same casting or billet. This may be advantageous for simplifying assembly of the electric water heating system 10, and also for reducing the number of interfaces requiring sealing. In some other examples, the power component cooler 22 and the connection manifold 40 may be separate components attached and sealed to one another, as shown in the examples of the accompanying figures.

[0072] Reference is now made to Figures 3 and 4 and in particular Figure 5 which shows the power component cooler 22 in more detail. As described previously, the power electronics components 20 are thermally coupled to the power cooling duct 24. For example, as shown in Figures 3 and 5, the power electronics components 20 may be thermally coupled to the power cooling duct 24 via a cooling plate 42. Attaching the power electronics components 20 to the cooling plate 42 may be advantageous for transferring heat away from the power electronics components 20 in use.

[0073] In some examples (not shown), the cooling plate may be separable from the power component cooler 22. In such an example, the cooling plate 42 may also facilitate modular assembly of the electric water heating system 10 whereby the plurality of power electronics components 20 are first attached to the cooling plate 42 before the cooling plate 42 is attached to the power component cooler 22 in a simple process, with the power electronics components 20 already attached. For example, the power electronics components 20 may be attached to the cooling plate 42 with an attachment surface 44 of the cooling plate 42 oriented substantially horizontally, for ease of assembly. When the cooling plate 42 is then attached to the power component cooler 22, the attachment surface 44 of the cooling plate 42 may extend substantially vertically. This may be preferable for packaging the power electronics components 20 efficiently.

[0074] In examples including a separable cooling plate 42 (not shown), the power cooling duct 24 may be defined by a side portion 46 of the power component cooler 22, and the cooling plate 42 may be attached and thermally coupled to the side portion 46. In some examples (not shown) the side portion 46 to which the cooling plate 42 is attached may itself be removable. For example, a removable side portion 46 may facilitate access to the power cooling duct 24 for maintenance and inspection.Alternatively, as shown in the examples in the accompanying figures, the cooling plate 42, i.e. the component or portion to which the power electronics components 20 are attached, may itself define part of the power cooling duct 24. For example, the cooling plate 42 may be part of the power component cooler 22. It follows that in some examples the power electronics components 20 may be attached directly to the power component cooler 22, and the side portion 46 of the power component cooler 22 may therefore be considered to define the cooling plate 42, as shown in the examples of the accompanying figures. Such a configuration may be more cost effective due to the reduction in part count and material cost, and may provide a more direct thermal coupling between the power electronics components 20 and the power cooling duct 24.

[0075] Referring again to Figure 5, in some examples the power electronics components 20 may include an AC to DC isolation transformer 48. Such a transformer 48 may produce a substantial amount of heat during operation. For example, the transformer may produce around 50 W of heat. To effectively cool the transformer 48 and recover heat produced by the transformer 48, the transformer 48 may be housed in a heat conductive housing 50 which is thermally coupled to the power cooling duct 24. For example, the heat conductive housing 50 may be attached to the cooling plate 42, or directly to the side portion 46 of the power component cooler 22 in some examples, to thereby conduct heat from the transformer 48 to the power cooling duct 24. To further improve the transfer of heat away from the transformer 48, in some examples the transformer 48 may be surrounded by a thermally conductive adhesive potting compound (not shown) in the heat conductive housing 50. Such an adhesive may bond the transformer 48 to an interior of the heat conductive housing 50 and thereby provide an effective thermal bridge for conducting heat from the transformer 48 to the housing 50.

[0076] With general reference to all of the accompanying figures, the electric water heating system 10 is configured to facilitate cooling of the battery cells 16 and power electronics components 20, as previously described. Notably, at the same time as cooling the battery cells 16 and power electronics components 20, the power cooling duct 24 and battery cooling duct 18 facilitate the recovery of heat produced by these components. This recovered heat can be reused to pre-heat a flow of incoming water 52 upstream of a water inlet 54a of the electrical water heating device 14. This may reduce the power required by the electrical water heating device 14 for heating the flow of incoming water 52 to a desired temperature before discharging the heated water from a water outlet 54b of the heating device 14.For example, with reference to the schematic diagram in Figure 6, in some examples the electrical water heating system 10 may include a heat exchanger 56. The heat exchanger 56 may be fluidly coupled to the power cooling duct 24. For example, the power component cooler 22 may define a power cooling duct outlet 26b that is fluidly coupled to the heat exchanger 56. The heat exchanger 56 may therefore receive heat from the power electronics components 20 via heat exchange fluid flowing through the power cooling duct 24 to the heat exchanger 56. It follows that in such an example, the power electronics components 20 may be thermally coupled to the flow of incoming water 52 via the power cooling duct 24 and the heat exchanger 56.

[0077] Finally, Figure 7 is a schematic diagram showing another example in which the power electronics components 20 are thermally coupled to the flow of incoming water 52 for pre¬ heating the water 52. As shown, in some examples the power cooling duct 24 may be fluidly coupled to the water inlet 54a of the electrical water heating device 14. Accordingly, the incoming flow of water 52 may serve as the heat exchange fluid and may receive heat in the power cooling duct 24 from the power electronics components 20.

[0078] As described previously, in some examples the battery cells 16 may provide a thermal mass for storing heat produced by the power electronics components 20. Whilst not shown in the diagrams of Figures 6 and 7, in some examples operation of the electric water heating system 10 may include flowing heat exchange fluid from the power cooling duct 24 to the battery cooling duct 18. For example the heat exchange fluid may be flowed in reverse, from the power cooling duct 24 to the battery cooling duct 18, or the system 10 may include one or more additional ducts (not shown) which bypass the heat exchanger 56 and / or electrical water heating device 14 and return heated heat exchange fluid to the battery cooling duct 18 from the power cooling duct 24. Accordingly, the battery cooling duct 18 may receive heated heat exchange fluid from the power cooling duct 24, in some examples. The battery cells 16 may then receive heat from the heat exchange fluid in the battery cooling duct 18, in some examples. Such operation of the electric water heating system 10 may be advantageous for maintaining the temperature of the battery cells 16 within a preferred range.

[0079] Further, such operation of the electric water heating system 10 may be advantageous during charging of the cells 16. For example, the battery cells 16 may be charged at a time when there is no ongoing demand for heated water, i.e. when the battery cells 16 are not being discharged to power the electrical water heating device 14. Operating the power electronics components 20 to charge the battery cells 16 may produce a substantialamount of heat. Using the battery cells 16 as thermal mass may advantageously facilitate the storage of such heat produced by the power electronics components 20 during charging of the cells 16. After receiving and storing the heat in the battery cells 16, the heat stored in the battery cells 16 may be used to pre-heat the incoming flow of water 52. For example, the heat exchange fluid may be flowed through the battery cooling duct 18 to receive heat from the battery cells 16, in accordance with the examples described with reference to Figures 6 and 7.

[0080] The description provided herein serves to demonstrate a plurality of possible examples of the present invention. It will be appreciated that features described in relation to any of the examples above may be readily combined with any other features described with reference to other examples without departing from the scope of the invention as defined in the appended claims.

Claims

Claims:

1. An electric water heating system comprising:a fluid-cooled battery pack comprising at least one battery cell and at least one battery cooling duct thermally coupled to the at least one battery cell;an electrical water heating device electrically coupled to the at least one battery cell;a plurality of power electronics components located above the fluid-cooled battery pack and electrically coupled to the at least one battery cell, anda power component cooler for cooling the power electronics components, the power component cooler defining at least part of a power cooling duct that is thermally coupled to the power electronics components and fluidly coupled to the battery cooling duct such that, in use, a heat exchange fluid flows through both the battery cooling duct and the power cooling duct.

2. The electric water heating system of claim 1 , wherein the battery pack comprises a plurality of battery modules, each battery module comprising a cell housing which houses at least one battery cell and a module duct which defines part of the battery cooling duct.

3. The electric water heating system of claim 2, wherein the battery cooling duct is defined in part by one or more duct connectors, and wherein each duct connector is sealed to at least one of an inlet and / or an outlet of a respective module duct at a seal interface to fluidly couple the module ducts of adjacent battery modules.

4. The electric water heating system of claim 3, wherein a plurality of the cooling duct connectors are defined by a connection manifold.

5. The electric water heating system of claim 4, wherein the connection manifold additionally defines at least part of the power cooling duct.

6. The electric water heating system of claim 4 or claim 5, wherein the connection manifold defines at least part of the power component cooler.

7. The electric water heating system of any preceding claim, further comprising a cooling plate thermally coupled to the power cooling duct, wherein the power electronics components are attached to the cooling plate and thermally coupled to the cooling plate.

8. The electric water heating system of claim 7, wherein the power cooling duct is defined in part by the cooling plate.

9. The electric water heating system of claim 7, wherein the power cooling duct is defined in part by a side portion of the power component cooler, and wherein the cooling plate is attached and thermally coupled to the side portion.

10. The electric water heating system of claim 9, wherein the side portion of the power component cooler is removable from a main body of the power component cooler, and wherein the cooling plate is attached and thermally coupled to the removable side portion.

11. The electric water heating system of any of claims 7 to 10, wherein the power electronics components are attached to a substantially vertically-extending attachment surface of the cooling plate.

12. The electric water heating system of any preceding claim, wherein the power cooling duct comprises a serpentine flow path.

13. The electric water heating system of any preceding claim, wherein the power electronics components comprise an AC to DC isolation transformer.

14. The electric water heating system of claim 13, wherein the AC to DC isolation transformer is housed in a heat conductive housing which is thermally coupled to the power cooling duct.

15. The electric water heating system of claim 14, wherein the isolation transformer is surrounded by a thermally conductive adhesive potting compound bonding the isolation transformer to an interior of the heat conductive housing.

16. The electric water heating system of any preceding claim, wherein the electrical water heating device comprises a water inlet configured to receive a flow of incomingwater and a water outlet configured to discharge heated water, and wherein the power electronics components are thermally coupled to the flow of incoming water at the water inlet via the power cooling duct.17 The electric water heating system of claim 16, further comprising a heat exchanger fluidly coupled to the power cooling duct such that the power electronics components are thermally coupled to the flow of incoming water via the power cooling duct and the heat exchanger.

18. The electric water heating system claim 17, wherein the power component cooler defines a power cooling duct outlet that is fluidly coupled to the heat exchanger.

19. The electric water heating system of claim 16, wherein the power cooling duct is fluidly coupled to the water inlet of the electrical water heating device.

20. The electric water heating system of any preceding claim, wherein the power component cooler defines a power cooling duct inlet that is fluidly coupled to the battery cooling duct and configured to receive a flow of heat exchange fluid from the battery cooling duct.

21. The electric water heating system of any preceding claim, wherein the power electronics components comprise a resistor, such as a snubber resistor, and wherein the resistor is thermally coupled to the power cooling duct.

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