Systems and methods for dynamic fluid heating in electric vehicles

Abstract

A system and method for heating a vehicle component is provided, comprising one or more cells for holding a fluid, each cell including one or more electrode pairs disposed therein. The one or more cells are arranged along a flow path including an inlet to the one or more cells and an outlet from the one or more cells. A controller is provided configured to regulate the flow of the fluid from the inlet to the one or more cells, determine an electrical conductivity or specific conductance of the fluid in the one or more cells, determine from the electrical conductivity or specific conductance of the fluid a voltage to apply from a high voltage battery or an external power source disposed outside the vehicle across the one or more electrode pairs at a current sufficient to heat the fluid therein, and pass the current from the one or more electrode pairs to the fluid to produce a heated fluid, the heated fluid transferring heat to one or more vehicle components via the outlet.

Description

[Technical field]

[0001] The present invention relates to a method and device for heating a fluid, and more particularly to heating a thermally conductive mixture in a vehicle. [Background technology]

[0002] Electric and hybrid electric vehicles are becoming increasingly desirable to vehicle owners. One of the most notable advantages of using electric vehicles includes the elimination of potentially harmful greenhouse gas emissions emitted by internal combustion engines. Furthermore, battery technology has advanced such that a reasonably sized battery pack can provide sufficient range and acceleration acceptable to most drivers. To provide a usable electric vehicle, the battery pack must be efficiently charged (ideally as quickly as possible) and discharged multiple times.

[0003] One challenge faced by electric vehicle designers involves the sensitivity of key electric vehicle components, including the high voltage battery, to temperature. More specifically, the maximum charge and discharge currents of the battery vary based on, among other things, the temperature of the battery. The temperature of the battery may vary during operation due to chemical reactions occurring within the battery and the ambient temperature of the environment in which the vehicle is located. For example, if charging occurs when the battery temperature is below a predetermined limit, the maximum charge current and operating life of the battery may be significantly reduced. If the battery temperature exceeds a predetermined operating limit, the charging and discharging efficiency of the battery, as well as the operating life of the battery, may also be less than optimal. Maintaining key electric vehicle components at optimal operating temperatures is essential and can be achieved through effective thermal management. Effective thermal management can improve the operating performance and life of key components.

[0004] Furthermore, existing heaters for the vehicle's combustion engine may not be suitable for heating the battery pack of an electric vehicle. Many existing engine block heaters are powered by 12V or 24V sources. The watt density of the heating element is defined accordingly. While these heaters perform the desired functions, they cannot simply be installed in an electric vehicle with a high voltage source in the range of about 450VDC. Also, controlling the heaters associated with the high voltage circuit becomes very important to ensure that overheating conditions of the main vehicle components are avoided. Therefore, it would be beneficial to provide a temperature control system that can maintain a desired optimum temperature for each of the main electric vehicle components, and more specifically, the high voltage battery.

[0005] Heaters are known that utilize liquid coolants as the fluid to be heated and have a heating element to generate heat that must be transferred to the liquid coolant. Liquid coolants are identified as the liquid to be heated because these types of liquids are commonly used, have good heat capacity and thermal conductivity to withstand high and very low temperatures, and are formulated with additives to maintain the required level of thermal conductivity and to keep the conduits through which they circulate in good condition. Nevertheless, the liquid to be heated will hereinafter be generally referred to as a fluid or a thermal fluid.

[0006] An example of a known heater is shown in US Patent Application Publication No. 2012 / 0295141. This document describes a coolant heater including a housing, a heating element, and a thermistor. The heater is suitable for heating the battery of an electric vehicle. The element, like a kettle, is in heat transfer relationship with the coolant held in the housing. The element is a resistive heating element manufactured with a specific shape to provide the desired watt density (in this case about 30 watts per square centimeter, relatively large to achieve the necessary 5000 watts or more in most vehicle applications). Ideally, the coolant heater must be as small and light as possible, designed to occupy as little space as possible to allow for optimization of the installation, and such space savings can be used for other elements such as battery storage.

[0007] To heat the coolant, power is selectively provided (and not provided) to the element using pulse width modulation. Such a control strategy can reduce the total amount of energy provided to the element over long periods of operation and can provide closed-loop control of the heater function based on the signal provided by the thermistor. However, heating the element by pulse width modulation, together with the overall design, makes the heater susceptible to thermal inertia, making it very difficult to dynamically and accurately control the temperature of the coolant circuit which makes an inappropriate thermal management strategy. Furthermore, the surface temperature of the housing can become very high (on the order of +300° C.) due to the significant heat exchange between the coolant and the housing, making it unsuitable for certain locations in the vehicle, e.g., near sensitive electronic components, indeed the battery itself, which can cause damage.

[0008] Attempts have been made to address some of these shortcomings and thereby improve the overall thermal management efficiency by using thick film heating elements, e.g., polymer PTC heating elements. However, while such designs improve the thermal inertia problem, it remains a major challenge to responsive energy and effective coolant thermal management.

[0009] It is also known that when a heating element comes into contact with water (as is the case for both concepts), scale tends to form on the element unless the element is coated with a material that prevents the formation of scale and / or the water is filtered. When scale forms on a heating element, the element becomes less efficient as a heater and can cause permanent damage to the heating element.

[0010] It would be desirable to provide a system and method that ameliorates, or at least reduces, one or more of the above problems, or to provide an alternative.

[0011] It would also be desirable to provide a system and method that improves upon or overcomes one or more of the drawbacks or disadvantages of known vehicle fluid heating systems and methods, particularly electric vehicles.

[0012] The reference herein to a patent document or other matter offered as prior art should not be construed as an admission or suggestion that the document or matter was known or that the information it contains was part of the common general knowledge at the priority date of any of the claims. Summary of the Invention [Means for solving the problem]

[0013] According to one aspect of the present invention, there is provided a system for heating a vehicle component, the system comprising: one or more cells for holding a fluid, each cell including one or more electrode pairs disposed therein; the one or more cells arranged along a flow path including an inlet to the one or more cells and an outlet from the one or more cells; and a controller configured to regulate the flow of the fluid from the inlet to the one or more cells, determine an electrical conductivity or specific conductance of the fluid in the one or more cells, determine from the electrical conductivity or specific conductance of the fluid a voltage to apply from a high voltage battery or an external power source disposed outside the vehicle across the one or more electrode pairs with a current sufficient to heat the fluid therein, and pass the current from the one or more electrode pairs to the fluid to produce a heated fluid, the heated fluid transferring heat to one or more vehicle components via the outlet. The one or more heating cells can not only hold the fluid but also facilitate the flow of the fluid. The one or more power pairs may be formed by dividing a single electrode pair into multiple electrode section pairs or segments, each segment having its own effective surface area, which may be the same size or may be different sizes.

[0014] Advantageously, the system is suitable for heating a fluid by passing an electric current through the fluid from the one or more electrode pairs. The system is dynamic and not subject to thermal inertia, and is therefore suitable for passing a cooled fluid, for example from a battery cooling subsystem coupled to a coolant loop containing a coolant (i.e., a heat transfer medium). That is, the cooling loop is thermally coupled to the system, thereby ensuring that the temperature of the battery can be maintained within its preferred operating range regardless of the ambient temperature.

[0015] The voltage applied to the electrodes may be direct current (DC). In either case, the power source may be provided by a battery. However, alternating current (AC) may be used in some embodiments, whereby power may be provided by a single-phase or three-phase source external to the vehicle. Various electronic components may be provided to switch the power source.

[0016] In one or more embodiments, the one or more cells for holding the fluid are in close proximity to the one or more vehicle components. Due to the high operating voltage and relatively high electrical conductivity of a typical coolant solution of a mixture of water and ethylene glycol, the system can have a very compact and lightweight form factor and can be placed in close proximity to temperature sensitive components without operating long and complex thermal circuits or loops.

[0017] In one or more embodiments, the one or more vehicle components include one or more of the high voltage battery, a DC motor, a heating, ventilation and air conditioning (HVAC) system, and drive electronics. It will be appreciated that the system may be coupled to a variety of possible configurations of heat exchange known in the art, including thermal jackets, thermal plates with specially designed fluid passages, heat sinks, radiators, finned inserts, and the like.

[0018] In one or more embodiments, the specific conductance of the fluid is greater than the specific conductance of water. Advantageously, this results in smaller electrodes and a more compact overall system. The specific conductance of the fluid may be in the range of about 2,500 to 5,000 μS / cm, including mixtures of water and ethylene glycol.

[0019] In one or more embodiments, the controller monitors a characteristic of the mixture, including the quality or concentration of the ethylene glycol mixture. This can be done by measuring the current drawn by the mixture. Advantageously, the characteristic can be provided through an on-board diagnostics (OBD) port or wirelessly (e.g., using various types of wireless communication technologies) to provide advanced diagnostic features. The characteristic relates to the quality and concentration of the ethylene glycol mixture.

[0020] In one or more embodiments, the controller monitors the quality of ethylene glycol or the concentration of the mixture of ethylene glycol to maintain a desired thermal conductivity of the mixture.

[0021] In one or more embodiments, the controller is configured to manage the thermal conductivity of the ethylene glycol mixture by monitoring a specific conductance of the mixture. The controller may be configured to provide dynamic and active temperature management of the mixture, thereby ensuring that optimal operating temperatures of the one or more vehicle components are maintained.

[0022] In one or more embodiments, the controller is configured to manage the thermal conductivity of the mixture, thereby ensuring that optimal operating temperatures of the one or more vehicle components are maintained.

[0023] In one or more embodiments, the high voltage battery is a lithium ion battery used for vehicle propulsion in a hybrid vehicle or a battery electric vehicle (BEV). Charging lithium ion (Li-ion) battery cells in electric vehicles is difficult due to constraints related to battery performance or degradation. For example, under some conditions (e.g., certain temperatures), charging a Li-ion battery may cause lithium deposition on the anode of the battery. The deposition of lithium on the anode causes performance degradation such as shorter charging cycles, shorter battery life, or internal short circuit of the cell. The internal short circuit of the cell causes heat generation that leads to failure of the battery cell.

[0024] In one or more embodiments, the controller is configured to determine the electrical conductivity or specific conductance of the fluid, thereby determining the voltage to continuously apply across the one or more electrode pairs. The controller is further configured to provide the required dynamic temperature management by determining the electrical conductivity or specific conductance of a fluid, and determining the voltage to continuously apply across one or more electrode pairs to provide dynamic and effective temperature management.

[0025] In one or more embodiments, the one or more electrode pairs are segmented into two or more segments, each constituent segment being selected by the controller to be individually electrically energized. Applying a voltage across the two or more segments individually increases or decreases the effective surface area of ​​the one or more electrode pairs. Advantageously, the conductivity or specific conductance gradient is thereby managed. Activating individual segments of the segment electrodes can be done in a manner that allows for very precise delivery of the desired current and voltage by the segment electrodes. Each segment electrode may be divided into segments of various sizes to allow for combinations of segments to be selected to increase the accuracy of the selection of the desired effective area. For example, if the segment electrode is divided into three segments, the segments may have relative effective areas in a ratio of 1:2:4, i.e. the segments preferably constitute 4 / 7, 2 / 7 and 1 / 7 of the total effective electrode area, respectively. In such an embodiment, appropriate activation of the three electrode segments allows for the selection of any one of the seven available effective areas. Alternative segment area ratios and numbers of segments may be provided. For example, one or more electrode pairs are segmented into n segments each having an effective surface area in the ratio 1:2:···:2(n−1).

[0026] In one or more embodiments, the voltage across the two or more segments increases or decreases the effective current drawn by the fluid depending on the electrode surface area. The initial voltage may be determined so that the current drawn by the fluid when a voltage is applied across one or more electrode pairs does not exceed the peak current rating of the power source or the peak current rating of the power source control device supplying the voltage to the electrode pairs. The peak current rating may be the maximum current the power source can handle without tripping or suffering damage or irreversible damage. Advantageously, this protects the power source (which is expensive and potentially flammable in a vehicle) and the power source control device supplying the voltage to the electrode pairs.

[0027] In one or more embodiments, the two or more segments are uniformly sized.

[0028] In one or more embodiments, two or more of the segments are different sizes.

[0029] In one or more embodiments, the one or more electrode pairs are segmented into n segments each having an effective surface area in the ratio 1:2:···:2(n−1).

[0030] In one embodiment, the one or more electrode pairs are substantially parallel and disposed in a generally horizontal plane relative to the flow path.

[0031] In one embodiment, the one or more electrode pairs are substantially vertical and disposed in a plane approximately perpendicular to the flow path.

[0032] In one or more embodiments, the one or more electrode pairs are at least partially coated with an inert conductive material or a non-metallic conductive material, including conductive plastic materials, carbon impregnated materials, and combinations thereof. Advantageously, the material can withstand long-term exposure to a mixture of ethylene glycol and water without scale build-up or corrosion.

[0033] In one or more embodiments, the one or more electrode pairs are at least partially formed from a material selected from the group consisting of metallic or non-metallic conductive materials, which may include layered structures and may include various binding materials.

[0034] In one embodiment, the one or more electrode pairs are formed from conductive inert materials including graphite, carbon, and combinations thereof.

[0035] In one embodiment, the controller is further configured to measure a flow rate of the fluid through the flow path.

[0036] In one embodiment, the controller is further configured to increase or decrease a flow rate of the fluid flowing through the passageway to regulate a residence time of the fluid in the one or more cells. The residence time for a given volume of fluid to receive power from an electrode can be determined by measuring the flow rate of the fluid through the passageway. The flow rate may be limited by one or more thresholds related to flow rate and / or pumping or regulation of the fluid.

[0037] In one embodiment, the controller is further configured to measure a temperature of the fluid flowing through the flow path, the controller is further configured to measure the temperature of the fluid at the outlet and provide the temperature as feedback to a temperature controller configured to increase or decrease heating of the fluid.

[0038] In one or more embodiments, the one or more cells are arranged in series along the flow path.

[0039] In one or more embodiments, the controller is further configured to not apply the voltage across the one or more electrode pairs if the electrical conductivity or specific conductance of the fluid is outside a predetermined range. Advantageously, this provides protection to the power supply and power control devices supplying the voltage to the electrode pairs.

[0040] In one or more embodiments, the inlet and the outlet extend at substantially 90 degrees to each other.

[0041] In one or more embodiments, the system further includes a pump that provides pressurized fluid in thermal communication with the one or more vehicle components.

[0042] In one or more embodiments, the controller includes a vehicle bus for communicating with other vehicle systems, which may include a Local Interconnect Network (LIN) and a very low cost vehicle sub-network.

[0043] In one or more embodiments, the battery voltage is in the range of about 250 to about 450 VDC. Advantageously, the high voltage reduces the gauge of wire that needs to be installed in the vehicle, which has weight and space saving benefits, further contributing to a compact and lightweight design.

[0044] In one or more embodiments, the one or more cells for holding fluid are made from a non-conductive lightweight plastic material. Advantageously, the lightweight plastic material reduces the overall weight of the system. Also, the fact that plastic is an insulator means that the surface temperature of any housing will not get too hot. That is, there is little heat exchange between the fluid and the housing, which does not cause damage, making it suitable for certain locations in the vehicle, such as near sensitive electronic components, and indeed the battery itself.

[0045] In one or more embodiments, the system is rated to operate up to about 9 kW.

[0046] According to another aspect of the invention, there is provided a method for heating a vehicle component comprising the steps of: providing an electrical connection to a high voltage battery used at least in part to propel the vehicle; providing one or more cells for holding a fluid, each cell including one or more electrode pairs disposed therein; arranging the one or more cells along a flow path, the flow path including an inlet to the one or more cells and an outlet from the one or more cells; determining an electrical conductivity or specific conductance of the fluid in the one or more cells; and determining from the electrical conductivity or specific conductance of the fluid a voltage to apply from the high voltage battery or an external power source disposed outside the vehicle across the one or more electrode pairs with a current sufficient to heat the fluid therein; and passing the current from the one or more electrode pairs to the fluid to produce a heated fluid, the heated fluid transferring heat to one or more vehicle components via the outlet.

[0047] In one or more embodiments, the one or more cells for holding the fluid are provided in proximity to the one or more vehicle components.

[0048] In one or more embodiments, the one or more vehicle components include one or more of the high voltage battery, a DC motor, a heating, ventilation and air conditioning (HVAC) system, and drive electronics.

[0049] In one or more embodiments, the specific conductance of the fluid is greater than the specific conductance of water.

[0050] In one or more embodiments, the specific conductance of the fluid is in the range of about 2,500 to 5,000 μS / cm.

[0051] In one or more embodiments, the fluid comprises a mixture of water and ethylene glycol.

[0052] In one or more embodiments, the method further comprises monitoring a property of the mixture, including the quality or concentration of ethylene glycol or the water and ethylene glycol mixture.

[0053] In one or more embodiments, the high voltage battery is a lithium ion battery used for vehicle propulsion in a hybrid or battery electric vehicle (BEV).

[0054] In one or more embodiments, the steps of determining the electrical conductivity or specific conductance of the fluid and determining the voltage to apply across the one or more electrode pairs are performed continuously along the flow path.

[0055] In one or more embodiments, the one or more electrode pairs are segmented into two or more segments, each segment configured to individually apply a voltage to the fluid.

[0056] In one or more embodiments, applying the voltages individually across the two or more segments increases or decreases the effective current drawn by the fluid depending on the electrode surface area.

[0057] In one or more embodiments, the two or more segments are uniformly sized.

[0058] In one or more embodiments, the two or more segments are different sizes.

[0059] In one or more embodiments, the one or more electrode pairs are segmented into n segments each having an effective surface area in the ratio 1:2:···:2(n−1).

[0060] In one or more embodiments, the one or more electrode pairs are substantially parallel and disposed in a generally horizontal plane relative to the flow path.

[0061] In one or more embodiments, the one or more electrode pairs are substantially vertical and disposed in a plane approximately perpendicular to the flow path.

[0062] In one or more embodiments, the one or more electrode pairs are at least partially coated with an inert conductive material or a non-metallic conductive material, including conductive plastic materials, carbon impregnated materials, and combinations thereof.

[0063] In one or more embodiments, the one or more electrode pairs are at least partially formed from a material selected from the group consisting of metallic or non-metallic conductive materials.

[0064] In one or more embodiments, the one or more electrode pairs are formed from conductive, inert materials including graphite, carbon, and combinations thereof. In one or more embodiments, the method further comprises measuring a flow rate of the fluid through the flow path.

[0065] In one or more embodiments, the method further comprises increasing or decreasing a flow rate of the fluid through the flow path to adjust a residence time of the fluid in the one or more cells.

[0066] In one or more embodiments, the method further comprises measuring a temperature of the fluid flowing through the flow passage.

[0067] In one or more embodiments, the method further comprises measuring the temperature of the fluid at the outlet and providing the temperature as feedback to a temperature controller configured to increase or decrease heating of the fluid.

[0068] In one embodiment, the one or more cells are arranged in series along the flow path.

[0069] In one or more embodiments, the method further comprises not applying or varying the voltage across the one or more electrode pairs if the electrical conductivity or specific conductance of the fluid is outside a predetermined range.

[0070] In one or more embodiments, the inlet and the outlet extend at substantially 90 degrees to each other.

[0071] In one or more embodiments, the method further includes providing a pump to provide pressurized fluid in thermal communication with the one or more vehicle components.

[0072] In one or more embodiments, the method further includes providing a connection to a vehicle bus that communicates with other vehicle systems. The vehicle bus may include a Local Interconnect Network (LIN) and a very low cost vehicle sub-network.

[0073] In one or more embodiments, the battery voltage is in the range of about 250 to about 450 VDC.

[0074] In one or more embodiments, the one or more cells for holding fluid are made from a non-conductive lightweight plastic material.

[0075] In one or more embodiments, the one or more electrode pairs are rated to operate at up to about 9 kW.

[0076] According to another aspect of the invention, a method for heating a vehicle component includes the steps of passing a fluid along a flow path from an inlet to an outlet, the flow path including at least a first cell and a second cell arranged along the flow path such that the fluid passing through the first cell subsequently passes through the second cell, each cell including at least one electrode pair between which an electric current flows in the fluid to generate heat in the fluid as it passes along the flow path, at least one of the cells including at least one segment electrode, the segment electrode comprising a plurality of electrically isolable segments, the effective surface area of ​​the segment electrodes being controllable by selectively activating the segments, such that upon application of a voltage to the activated electrode segments a current drawn is dependent in part on the effective surface area; determining from the measured fluid conductivity or specific conductance a required voltage and current to be supplied to the fluid by the first cell to raise a temperature of the fluid therein by a first amount; determining a heated fluid conductivity or specific conductance resulting from operation of the first cell; determining from the heated fluid conductivity or specific conductance a required voltage and current to be supplied to the fluid by the second cell to raise a temperature of the fluid therein by a second amount; activating segments of the segment electrodes to effect delivery of a desired current and voltage by the segment electrodes; and transferring heat from the heated fluid through the outlet to one or more vehicle components.

[0077] In one or more embodiments, the outlet is coupled to a heat exchange system within the vehicle.

[0078] In one or more embodiments, the heat exchange system includes a plurality of valves for distributing thermal energy among the one or more vehicle components.

[0079] In one or more embodiments, the one or more vehicle components include a high voltage battery used for vehicle propulsion in a hybrid vehicle or a battery electric vehicle (BEV). [Brief description of the drawings]

[0080] The invention will now be described in more detail with reference to the accompanying drawings, in which it is to be understood that the particularity of the drawings does not supersede the generality of the preceding description of the invention. [Figure 1] FIG. 1 illustrates a block diagram of a plug-in electric vehicle fitted with a fluid heater for heating major vehicle components in accordance with an embodiment of the present invention. [Diagram 2] FIG. 2 shows a simplified block diagram of a system for heating a vehicle component passing through n heating cells in accordance with an embodiment of the present invention. [Diagram 3] FIG. 3 illustrates a flow chart of a method for heating a vehicle component with a fluid passing through n heating cells in accordance with an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0081] The present invention is suitable for electric vehicles, or "EVs," and the invention will be described in connection with that exemplary, but non-limiting, application.

[0082] FIG. 1 shows an overall block diagram 100 of a plug-in electric vehicle 102 in an embodiment of the present invention. The vehicle 102 includes four wheels 104 driven by a DC motor 110, potentially via some additional drive components 108. The DC motor is powered by an internal power source 120. In the illustrated embodiment, the internal power source 120 is a rechargeable DC power source formed by a combination of DC motor drive electronics and a battery, such as a lithium-ion battery. The voltage of the internal power source 120 is, for example, about 250-450 VDC. The internal power source 120 is charged via an external power source 116 via a charging port 118a. The charging port 118b is a power interface for receiving power from the external power source 116 outside the vehicle 102. During charging, the connector 118a of the charging cable 126 is connected to the charging port 118b.

[0083] The charging port 118b is electrically connected to the internal power source. When the connector 118a is connected to the charging port 118b, the various interconnected electronic systems convert the power provided by the external power source 116 into the power required by the internal power source 120 to charge it. Those skilled in the art will recognize appropriate designs to provide the charging functions described above, such as one or more battery chargers, converters (DC / DC, AC / DC, and / or DC / AC), and / or inverters.

[0084] Vehicle 102 may also include components such as heater and / or air conditioning 124, electronic control unit (ECU) 122, inverters, converters, and power steering motors or pumps (not shown), as known in the art. Modern vehicles utilize many ECUs to control the operation of components such as the engine, powertrain, transmission, brakes, suspension, on-board entertainment systems, and communication systems. The ECUs control the basic operation of modern vehicles, from power steering to braking to acceleration. Some automobiles may also be equipped with ECUs configured to provide advanced diagnostic features through an on-board diagnostics (OBD) port or over the air (e.g., using various types of wireless communication technologies). In the illustrated embodiment, ECU 122 is electrically connected to several vehicle components via bus 112 to provide at least some of their aforementioned purposes. To avoid overly complex drawings, bus 112 is not shown connected to all vehicle components. However, in modern vehicles, other components, including the drivetrain, may be connected to the OBD port.

[0085] Proximate to each of the vehicle components 108, 110, 120, 122, and 124 are one or more fluid heaters 106. The heaters 106 are thermally coupled to each of the vehicle components 108, 110, 120, 122, and 124 via a heat exchanger 114. Various possible configurations of the heat exchanger 114 are known in the art.

[0086] 1 provides a compact fluid heater 106 that is effectively coupled to the vehicle component to be heated via heat exchanger 114 without complex thermal loops or circuits and the associated heat dissipation associated with said loops. For example, heat transfer paths and patterns need to be comprehensively designed to reduce unwanted heat loss, and to that end, several improvements can be made based on theories and methodologies from thermal science, including locating the heat source in close proximity to the component to be heated, thereby avoiding heat loss over long conductive or convective paths.

[0087] However, it will be understood that fewer than six fluid heaters may be used, in which case a thermal loop or circuit may be used that includes a circulating fluid, one or more pumps, one or more heat exchangers, and, optionally, a valve for controlling the flow. In some examples, the thermal loop optionally includes a port for filling the loop with fluid, and also optionally includes a reservoir tank. The thermal loop functions to transport and direct heat to and from components of the vehicle, particularly the battery, and redirect this heat to another loop or directly to the surrounding air as needed.

[0088] The fluid heaters 106 are used to heat a fluid that is circulated between the fluid heaters 106 and their respective heat exchangers 114 using a small pump. The heat exchangers 114 are used to transfer the heat to the vehicle components being heated. The level of heat transferred is controlled by the fluid heaters 106 and a controller, which will be described in more detail with reference to Figures 2 and 3.

[0089] In this or similar embodiments, the fluid heater 106 uses multiple electrode sections to apply electrical energy directly to the fluid under electronic control to heat the fluid, causing heating within the fluid itself.

[0090] The voltage for the fluid heater is provided by an internal power supply 120 or an external power supply 116 and governs the set fluid flow rate and changes in fluid conductivity. The fluid heater 106 is a closed loop continuous flow fluid heater and operates within constrained ranges of temperature and conductivity variation as the fluid flow is facilitated via a pump. Depending on the exterior temperature, the vehicle's components may be preconditioned to a particular temperature level when the vehicle is connected to an external power source 116 for charging. The interior can be preconditioned independently of the external power source 116.

[0091] 2 shows a simplified block diagram of a system for heating a fluid 200 in an embodiment of the invention. The fluid is caused to flow through three heat cells 202, 204, and 206 arranged along a flow path 208. The flow path 208 includes inlets 210 to the heat cells 202, 204, and 206, and outlets 212 from the heat cells 202, 204, and 206. The inlets and outlets extend substantially 180 degrees from one another, although other configurations are contemplated. The heat cells 202, 204, and 206 hold the flow path as it passes through, and one of ordinary skill in the art will recognize appropriate designs, e.g., tubes or pipes, to provide the above-mentioned functions.

[0092] In one or more embodiments, the heating cells 202, 204 and 206 are housed or integrated in a body 214. The body 214 is preferably made of a non-conductive and lightweight material, such as a synthetic plastic material. Advantageously, this makes the system very light (on the order of 1.7 kg), which is desirable in automotive applications. However, the body 214 may be connected to metal fixtures, such as copper pipes or nipples, which are conductive. Thus, a ground connection 216, shown in FIG. 2, is included at the inlet 210 and outlet 212 of the body 214 to electrically ground any metal tubes connected to the system 200. The ground connection 216 is ideally connected to the electrical ground of the vehicle in which the embodiment of the heating system is installed. The ground connection 216 allows the voltage of the electrodes to draw a current through the water passing through the system 200, resulting in the activation of the ground fault protection. The system 200 includes a ground fault protection circuit. As will be appreciated by those skilled in the art, ground-fault protection circuits are designed to detect minimal ground-fault currents and then disconnect power from downstream circuits to protect personnel or equipment from these currents.

[0093] It will be appreciated that in automotive applications, system 200 is required to comply with various safety standards, including ISO 16750-2:2010(E), which requires electrical systems contained in electric vehicles to undergo insulation resistance testing. For example, system 200 must pass a test that ensures the minimum amount of ohmic resistance required to avoid current flow between galvanically isolated circuits, where insulation is provided by either inductive or capacitive means and conductive parts of system 200. Such testing can provide an indication of the relative quality of the insulation system, including the material of body 214. The ability to manufacture body 214 from a non-conductive plastic material provides a significant advantage over the prior art heaters described in the Background section.

[0094] In the illustrated embodiment, the flow path 208 includes three heat cells 202, 204, and 206, each including a respective set of electrode pairs 202a, 204a, and 206a. However, it will be appreciated that additional or fewer heat cells may be used. The electrodes may be metallic or may be non-metallic conductive materials, such as conductive plastic materials, carbon, carbon-impregnated materials, and the like.

[0095] It is important that the electrode substrate and coating are selected from a group of electrically conductive materials (or combination of materials) to minimize chemical reactions and / or electrolysis while heating the water, ethylene glycol mixture.

[0096] The electrode pairs may also be fabricated from conductive inert materials such as graphite, carbon, and combinations thereof, and they may be fabricated such that they are separate electrodes but share a common substrate, or the like.

[0097] In one or more embodiments, one electrode of each electrode pair 202a, 204a, and 206a is segmented into two or more segments, with each segment configured to apply a voltage individually. The segment electrodes of each electrode pair 202a, 204a, and 206a are connected to a common switched electrical supply path 218 via separate voltage supply power control devices Q1, Q2, ..., Qn, while the other of each electrode pair 202b, 204b, and 206b, respectively, is connected to an input DC voltage supply source 220. The separate voltage supply power control devices Q1, Q2, ..., Qn switch the common power supply according to power management control provided by a controller 222. The controller 222 may include a microprocessor that interacts with other components of the system 200 to regulate or measure the flow rate of fluid, detect electrical leaks, measure the temperature at the inlet 210 and / or outlet 212 (or at other locations along the flow path 208), and / or measure the current 224 drawn by the fluid in the heating cells 202, 204, and 206 (or at other locations along the flow path 208).

[0098] The current supplied to the heating cell 202, which also supplies the heating cells 204 and 206, is measured by a current measuring device 224. Only one current measuring device 224 is shown. However, it will be understood that the current in each heating cell 202, 204 and 206 may be measured by an individual current measuring device 224. Current measurements made, for example, by Hall current sensors electrically connected to the outputs of the power control devices Q1, Q2, ..., Qn are communicated to the power management controller 222.

[0099] In one or more embodiments, a current measuring device 224 is coupled to the power control devices Q1, Q2, ..., Qn such that it is operable to determine the current being drawn from the DC power supply 220 by the fluid. A current amplifier may be used to amplify the output signal of the current measuring device 224. The amplified signal is then received by the controller 222 and compared to a threshold level. The calculated current threshold level is typically set as a range of amperes such that the current drawn by the fluid remains equal to or approximately equal to the threshold level only when the fluid flows through the flow path 208. While the system 200 is in use, the controller 222 compares the output of the current measuring device 224 to the threshold level and makes appropriate adjustments to the selection of the electrode pair combination as well as to the voltage supplied to the electrode pairs 202a, 204a, and 206a to maintain a substantially constant current to heat the fluid while consistently ensuring that the current handling capabilities of the power supply are not exceeded. However, when the system 200 enters a state of non-use, such as entering a standby mode, the controller 222 responsively removes the voltage applied to the heat cells 202 , 204 and 206 .

[0100] As a non-limiting example, the current measurement device 224 can sense slight increases in the detected flow of current through the fluid to determine the ideal voltage to apply across the electrode pairs 202a, 204a, and 206a to heat the fluid, i.e., the current measurement is provided as an input signal via the input interface 224 to the controller 222, which functions as a power supply controller.

[0101] In one or more embodiments, the controller 222 may also receive a signal via the input interface 224 from a flow metering device or flow switch incorporating a flow restriction 226 located near the inlet 210 to the body 214. The volume of fluid passing between any set of electrodes 202a, 204a, and 206a can be accurately determined by measuring the flow rate. Similarly, the residence time for a given volume of fluid to receive power from the electrodes can be determined by measuring the flow rate of the fluid through the passageway. It will be appreciated that the flow rate may be limited by one or more thresholds related to the flow rate and / or pumping or regulation of the fluid.

[0102] Heating of the fluid results from its exposure to the electrodes (as described above) in the heating cell. Heating is facilitated by providing the necessary current drawn by the fluid. In this application, the specific conductance of the fluid (e.g., a mixture of water and ethylene glycol) is in the range of about 2,500 to 5,000 μS / cm, i.e. significantly greater than water. This means that the electrodes will be significantly smaller than those used to heat water, which is exacerbated by the very high power supply voltages, considering that electric vehicles operate at very high DC voltages of about 250 to about 450 VDC. It will be understood that propylene glycol, as well as other mixtures of glycols including glycerol, trimethylolpropane, hexanetriol, pentaerythritol, and the like, are also suitable.

[0103] Thus, the current flowing through the fluid can be used as a measure of the electrical conductivity or specific conductance of that fluid, allowing the determination of the required changes in applied voltage and selected electrode combination required to heat the extracted current and maintain that heat very efficiently.

[0104] The electrical conductivity and specific conductance of a fluid change with increasing temperature, thus creating a gradient in specific conductance along the path of the fluid flow 208. In one or more embodiments, the controller 222 receives a signal from an input temperature measuring device 228 via the signal input interface 224 to measure the temperature of the fluid at the inlet 210. An output temperature measuring device 230 may be provided to measure the temperature of the fluid at the inlet 212. The signals from the input temperature measuring device 228 and the output temperature measuring device 230 are provided as feedback to the controller 222, allowing the temperature of the fluid to be accurately calculated and continuously monitored.

[0105] The system 200 of this embodiment can also accommodate changes in the conductivity or specific conductance of the fluid, whether resulting from the particular location where the system is installed, or from time to time at a single location, or due to changes in the temperature of the fluid. In this regard, the conductivity or specific conductance of the fluid is determined as being directly proportional to the current drawn by the fluid flowing through the heating cells 202, 204, and 206. Advantageously, these changes can also be interpreted by the controller 222 and used for diagnostic purposes. For example, a lower than expected conductivity of a mixture of water and ethylene glycol indicates poor quality ethylene glycol or the like. An indication of this is sent by the controller 222 via the OBD port or wirelessly (e.g., using various types of wireless communication techniques) 234 to an ECU configured to provide advanced diagnostic features. Other diagnostic information can also be sent in this manner, including, but not limited to, inlet temperature, outlet temperature, power usage, increase or deterioration of fluid quality and conductivity, power consumption, voltage, flow rate, error codes, and other diagnostic information. Similarly, the controller 222 receives information from the vehicle including, but not limited to, setting maximum applied power levels, coordinated power consumption with other devices, setting maximum and minimum fluid temperature limits, change temperature settings during operation or standby, error and fault management information, and on or off messages.

[0106] Variations in the conductivity or specific conductance of the fluid cause changes in the amount of current drawn by each electrode for a given applied voltage. This embodiment monitors such variations and ensures that the system 200 draws the desired level of current by initially selecting a corresponding combination of electrode segments before allowing the system to operate with the determined conductivity or specific conductance values. The electrodes represented by 202a, 204a, 206a are segmented into multiple electrode segments 202ai and 202aii, 204ai, 204aii, 206ai and 206aii.

[0107] For each electrode, the ai segments are typically fabricated to form about one-third or two-thirds of the active area of ​​the electrode, and the aii segments are typically fabricated to form about two-thirds or one-third of the active area of ​​the electrode. Selection of the appropriate segment or appropriate combination of segments thus allows the effective area of ​​the electrode to be any one of three available values ​​for the electrode area. As a result, for fluids of high conductivity, a smaller electrode area is selected to prevent the current drawn by the electrode from rising above a desired or safe level for a given voltage while maintaining the required current drawn to heat the fluid. On the other hand, for fluids of poor conductivity, a larger electrode area is selected so that the required current is drawn to affect the desired heating. The selection of the segments can be easily performed by activating or deactivating the power switch devices Q1,...,Qn as required.

[0108] In particular, the total surface area of ​​the selected electrode segments is specially calculated to ensure that the maximum rated current value of the power supply system is not exceeded.

[0109] In one or more embodiments, the controller 222 receives various monitored inputs and performs the necessary calculations regarding the selection of electrode active areas, desired electrode pair voltages and currents to heat the fluid flowing through the flow path 208. The controller 222 controls the supply of voltages from either an internal DC power supply or an external power supply (as described with reference to FIG. 1) connected to each of the electrode portions 202, 204, and 206.

[0110] The voltage supplies are separately controlled by separate control signals from the controller 222 to the power switch devices Q1,...,Qn. It will thus be understood that based on various parameters for which the controller 222 receives representative input signals, a calculation means under the control of a software program or firmware in the controller 222 calculates the control pulses required by the power switch devices to supply the necessary voltages to give the desired temperature of the fluid flowing through the flow path 208, as will be described with reference to FIG. 3. Pulse width modulation (PWM) control is not required, but the controller 222 is configured to accept modulated signals. This is because the system 200 essentially applies the heat transfer equation based on the requirements determined by the vehicle's control system. This system 200 can then dynamically change requirements according to the thermodynamic loads of the battery, drive electronics, drive motors, cabin coolant heating system, etc.

[0111] In some embodiments, the controller 222 converts readings from the current measuring device 224, temperature sensors 228 and 230, flow measuring devices or switches incorporating the flow restriction 226, power switch devices Q1, ..., Qn, etc., into digital values ​​and communicates messages based on these digital values ​​to the digital communication device 232. It should also be understood that filtering methods such as, but not limited to, moving average filters, equal weighted moving average filters, etc., or combinations of these filters that are particularly suited for implementation in firmware, may also be used. The messages can then be sent to other devices (e.g., computers, smartphones, tablets, laptop computers, desktop computers, server computers, among other forms of computer systems) via hardwired digital communication services such as, but not limited to, vehicle bus technologies, Ethernet, RS485, or wireless connections such as 802.11 Wi-Fi networks or Bluetooth™ for processing by the application 234 or cloud computing platforms. Advantageously, this can provide for remote monitoring and / or configuration of the system 200, making it convenient for an operator to modify parameters such as flow rate or power based on the properties of the fluid being heated (e.g., reducing the flow rate and / or increasing the temperature if the solution has low conductivity). Maintenance of the system can also be facilitated via the digital communication methods employed.

[0112] It will be appreciated that various control implementations are possible. For example, the system 200 may include an artificial intelligence-based control mechanism that may in some embodiments use a partially cloud-based service. As described above, increasing or decreasing the flow rate (i.e., increasing or decreasing the residence time that the fluid stays in the heating cell) or determining the voltage (and subsequently the current drawn) may be based on a number of sensor inputs via the interface 224, provided to the controller 222 (or another platform via the wireless transceiver 232). This coordination of communication and calculations may be done automatically within the controller 222, within the application 234, or within a cloud-hosted application. Additionally, the controller 222 may perform machine learning based on the input data. Based on this information, the system 200 may preemptively change the flow rate, voltage, temperature, etc.

[0113] Communication is These include, but are not limited to, AFDX, ARINC 492, Byteflight, CAN (Controller Area Network) an inexpensive low-speed serial bus for interconnecting automotive components, D2B (Domestic Digital Bus) a high-speed multimedia interface, FlexRay a safety-critical general-purpose high-speed protocol, IDB-1394, IEBus, I 2C, ISO 9141-1 / -2, J1708 and J1587, J1850, J1939 and ISO 11783 Adaptations of CAN for commercial (J1939) and agricultural (ISO11783) vehicles, Keyword Protocol 2000 (KWP2000) Protocol for automotive diagnostic devices (over serial lines or CAN), LIN (Local Interconnect Network) Very low cost in-vehicle sub-networks, SMARTwireX, SPI, VAN (Vehicle Area Network), UAVCAN (Uncomplicated Application-level Vehicular Communication And Networking), Wi-Fi 802.11, 6LowPan / ZIGBEE™ 802.15, Ethernet 802.3, Ethernet 802.11 and 802.15.4, and RS485. It includes buses, cables, wireless communication channels, radio-based communication channels, the Internet, local area networks (LANs), wireless local area networks (WLANs), wide area networks (WANs), cellular communication networks, or any Internet Protocol (IP) based communication network. In a preferred embodiment, the communication is performed using the LIN bus. The LIN bus is an inexpensive serial communication protocol that effectively supports remote applications within the car network. It is particularly targeted at mechatronic nodes in distributed automotive applications, but is equally suitable for industrial applications. It is intended to complement the existing CAN network that leads to a hierarchical network inside the car.

[0114] The wireless transceiver 232 may also be adapted to facilitate communication between a remote firmware update mechanism and the controller 222. As will be appreciated by one skilled in the art, the remote firmware update mechanism, in conjunction with the controller 222, may be adapted to periodically check for updates from a remote repository, download firmware updates, compare the downloaded firmware with existing firmware, determine the need to install the downloaded firmware, etc.

[0115] FIG. 3 shows a flow chart of a method for heating a fluid in embodiments of the invention, including the embodiment described with reference to FIG.

[0116] The method 300 begins at start block 302 and, in step 304, the electrical conductivity or specific conductance of a fluid is determined at an inlet to a first heating cell containing a first electrode pair. In one or more embodiments, the electrical conductivity or specific conductance is determined by the amount of current drawn by the fluid while an initial voltage is applied across the first electrode pair from a voltage supply power control device (i.e., Q1 as described with reference to FIG. 1).

[0117] In step 306, the electrical conductivity or specific conductance of the fluid determines a voltage to apply across the first electrode pair at a current sufficient to heat the fluid to a set temperature. In step 308, a combination of electrode segments is determined. For example, if the segmented electrode is divided into three segments, the segments have relative effective areas in a ratio of 1:2:4, i.e., the segments preferably constitute 4 / 7, 2 / 7, and 1 / 7 of the total effective electrode area, respectively. In one or more embodiments, all of the segments may be activated for fluids with a relatively low conductivity or specific conductance, and one or more segments may be activated for fluids with a relatively high conductivity or specific conductance.

[0118] Once the applied voltage and electrode segment combinations have been determined, in step 310 the current drawn by the fluid is measured.

[0119] At step 312, it is determined whether the system current limit has been exceeded. If the system current limit has been exceeded, the process ends at step 318. If the system current limit has not been exceeded, at step 314, it is determined whether there is sufficient current to heat the fluid to the set temperature.

[0120] In one or more embodiments, the method returns to step 316 where the electrical conductivity or specific conductance is continuously determined and appropriate adjustments are made to the supply voltages and electrode segment combinations in all heating cells 202, 204, and 206 to maintain a substantially constant current to maintain the fluid at the set temperature. Advantageously, by returning to step 316, the method can accommodate changes in the electrical conductivity or specific conductance of the fluid resulting from changes in the concentration of the ethylene glycol and water mixture, or the specific quality of the ethylene glycol that occur from time to time or on a location-specific basis.

[0121] In one or more embodiments, steps 310-316 may be repeated for n heating cells until the method ends at step 318.

[0122] It will be appreciated that some embodiments may be comprised of one or more general purpose or specialized controllers or processors (or "processing devices"), such as microcontrollers, microprocessors, digital signal processors, customized processors, and field programmable gate arrays (FPGAs), and unique stored program instructions (including both software and firmware) that control the one or more processors to implement some, most, or all of the functionality of the methods and / or apparatus described herein in conjunction with specific non-processor circuitry. Alternatively, some or all of the mechanisms are implemented by state machines without stored program instructions, or in one or more application specific integrated circuits (ASICs), with each function or some combination of specific functions being implemented as custom logic. Of course, a combination of the two approaches can be used.

[0123] The term "coated," as used herein with respect to a "coated electrode," may refer to the attachment of a material onto an outer surface of another material. The attachment may be partial or total coverage of the outer surface of the other material and may be by any mechanical, chemical, or other force or bond.

[0124] The term "fabricated" may refer to the manufacture of one or more electrode pairs made from conductive inert materials such as graphite, carbon, and combinations thereof.

[0125] The term "heat exchanger," as used herein, may refer to a device for transferring heat from one medium to another. Examples of heat exchangers include radiators, which may include coils, plates, fins, pipes, and combinations thereof.

[0126] The term "fluid" as used herein may refer to gas, liquid, gel, and combinations thereof. Cooling fluids or coolants assist in transferring heat within a thermal circuit. In some instances, a solid conductor may be used in place of a heat transfer fluid.

[0127] The term "thermally coupled," as used herein, may refer to two or more components or devices that are in communication such that heat can be exchanged (i.e., received or dissipated) between the two or more components or devices. Thermally coupled devices may be in close proximity or separated by a pipe or other medium for transferring or exchanging heat.

[0128] The term "thermal loop" as used herein may refer to a circuit that includes at least a circulating fluid, one or more pumps, a heat exchanger, an optional electric fluid heater, and an optional valve to control the flow rate. In some examples, the thermal loop optionally includes a port for filling the loop with fluid and also optionally includes a reservoir tank. The thermal loop functions to transport heat to the battery, direct heat from the battery, and reject this heat to another loop or directly to the ambient air, if desired.

[0129] The term "powertrain," as used herein, may refer to one or more of the engine, battery, electric motor, motor power electronics, battery power electronics, on-board battery charger, and DC-DC converter.

[0130] "Drivetrain" as used herein refers to the system in an automotive vehicle that connects the transmission to the driveshaft. Hybrid vehicles, for example, can include an electric drivetrain.

[0131] When the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification (including the claims), they specify the presence of stated features, integers, steps or components but do not exclude the presence of one or more other features, integers, steps or components or groups thereof.

[0132] While the present invention has been described in conjunction with a limited number of embodiments, it will be appreciated by those skilled in the art that many alternative modifications and variations are possible in light of the above description, and therefore, the present invention is intended to embrace all such alternatives, modifications and variations that fall within the spirit and scope of the present invention.

Claims

1. 1. A system for heating a component of a vehicle, comprising: one or more cells for holding a fluid, each cell including one or more electrode pairs disposed therein; the one or more cells arranged along a flow path including an inlet to the one or more cells and an outlet from the one or more cells; Regulating the flow of the fluid from the inlet to the one or more cells; determining the electrical conductivity or specific conductance of the fluid in the one or more cells; determining from the electrical conductivity or specific conductance of the fluid a voltage to apply across the one or more electrode pairs from a high voltage battery or an external power source located outside the vehicle with a current sufficient to heat the fluid therein; applying the current through the fluid from the one or more electrode pairs to generate a heated fluid, the heated fluid transferring heat to one or more vehicle components via the outlet; A controller configured as follows: A system comprising:

2. The system of claim 1 , wherein the one or more cells for holding the fluid are in proximity to the one or more vehicle components.

3. The system of claim 1 , wherein the one or more vehicle components include one or more of the high voltage battery, a DC motor, a transmission, a heating, ventilation and air conditioning (HVAC) system, and drive electronics.

4. The system of claim 1 , wherein the specific conductance of the fluid is greater than the specific conductance of water.

5. The system of claim 1 , wherein the fluid comprises a mixture of water and ethylene glycol.

6. 6. The system of claim 5, wherein the controller monitors a property of the mixture including a quality of ethylene glycol or a concentration of the water and ethylene glycol mixture.

7. 6. The system of claim 5, wherein the controller monitors a property of the mixture including a quality of ethylene glycol or a concentration of a water and ethylene glycol mixture by measuring the current drawn by the mixture.

8. 6. The system of claim 5, wherein the controller monitors properties of the mixture including the quality of ethylene glycol or the concentration of a water and ethylene glycol mixture to maintain a desired thermal conductivity of the mixture.

9. 6. The system of claim 5, wherein the controller is configured to manage the thermal conductivity of the mixture by monitoring the quality of the ethylene glycol and the concentration of the water and ethylene glycol mixture.

10. 6. The system of claim 5, wherein the controller is configured to manage a thermal conductivity of the mixture, thereby ensuring an optimal operating temperature of the one or more vehicle components is maintained.

11. The system of claim 1 , wherein the controller is configured to determine the electrical conductivity or specific conductance of the fluid, thereby determining the voltage to be continuously applied across the one or more electrode pairs.

12. The system of claim 1 , wherein the one or more electrode pairs are segmented into two or more segments, each segment configured to have a voltage applied to it individually by the controller.

13. The system of claim 1 , further comprising a pump that provides pressurized fluid in thermal communication with the one or more vehicle components.

14. The system of claim 1 , wherein the controller includes a vehicle bus for communicating with other vehicle systems.

15. The system of claim 1 , wherein the one or more cells for holding fluid are made from a non-conductive lightweight plastic material.

16. 1. A method for heating a vehicle component, comprising: providing an electrical connection to a high voltage battery used at least in part for propulsion of the vehicle; providing one or more cells for holding a fluid, each cell including one or more electrode pairs disposed therein; arranging the one or more cells along a flow path, the flow path including an inlet to the one or more cells and an outlet from the one or more cells; determining the electrical conductivity or specific conductance of the fluid in the one or more cells; determining from the electrical conductivity or specific conductance of the fluid a voltage to apply from the high voltage battery or an external power source located outside the vehicle across the one or more electrode pairs with a current sufficient to heat the fluid therein; passing the current through the fluid from the one or more electrode pairs to generate a heated fluid, the heated fluid transferring heat to one or more vehicle components via the outlet; A method for providing the above.

17. The method of claim 16 , wherein the one or more cells for holding the fluid are provided in proximity to the one or more vehicle components.

18. 20. The method of claim 16, wherein the one or more vehicle components include one or more of the high voltage battery, a DC motor, a heating, ventilation and air conditioning (HVAC) system, and drive electronics.

19. The method of claim 16 , wherein the specific conductance of the fluid is greater than the specific conductance of water.

20. The method of claim 16 , wherein the fluid comprises a mixture of water and ethylene glycol.

21. 21. The method of claim 20, further comprising monitoring a property of the mixture including the quality or concentration of ethylene glycol or a mixture of water and ethylene glycol.

22. 17. The method of claim 16, wherein the one or more cells for holding fluid are made from a non-conductive lightweight plastic material.

23. 1. A method for heating a vehicle component, comprising: passing a fluid along a flow path from an inlet to an outlet, the flow path including at least a first cell and a second cell arranged along the flow path such that the fluid passing through a first cell subsequently passes through a second cell, each cell including at least one electrode pair between which an electric current flows in the fluid to generate heat in the fluid as it passes along the flow path, at least one of the cells including at least one segment electrode, the segment electrode comprising a plurality of electrically isolable segments, the effective surface area of ​​the segment electrodes being controllable by selectively activating the segments, such that upon application of a voltage to the activated electrode segments a current drawn is dependent in part on the effective surface area; determining the conductivity or specific conductance of the fluid at the inlet; determining from the measured fluid conductivity or specific conductance a required voltage and current to be supplied to the fluid by the first cell to raise the temperature of the fluid therein by a first amount; determining the conductivity of a heated fluid or a specific conductance resulting from operation of the first cell; determining from the conductivity or specific conductance of the heated fluid a required voltage and current to be supplied to the fluid by the second cell to raise the temperature of the fluid therein by a second amount; activating segments of the segment electrodes to provide a desired current and voltage supply by the segment electrodes; transferring heat from the heated fluid through the outlet to one or more vehicle components; A method for providing the above.

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