Patent Description:
It has been observed that electric vehicles exhibit less efficiency at cold temperatures. In particular, the efficiency may be less when the vehicle is first operated.

Document <CIT> describes an electric drive unit for a motor vehicle which includes an electrical machine having a stator and a rotor. An inverter having a first switch unit energizes a first phase system (U, V, W) of the stator. A transmission is connected to the rotor for torque transmission. A lubricant circuit lubricates the transmission and/or cools the rotor. A first cooling circuit cools the first switch unit. A lubricant-coolant heat exchanger thermally couples the first coolant circuit and the lubricant circuit. A control device provides a dissipation-increasing operating mode for the first switch unit in order to increase a dissipation heating a coolant of the first coolant circuit. The lubricant-coolant heat exchanger transfers heat from the heated coolant to the lubricant circuit in order to reduce a viscosity of a lubricant.

Document <CIT> describes vehicle platforms and thermal management systems, subsystems, and components for use therewith. Thermal management architectures and systems incorporate thermal management cycles for one or more of drive train, energy storage and passenger cabin systems. Thermal manage architectures are provided such that the flow of heating and cooling fluids through such thermal management cycles may be combined in various configurations. Systems having thermal management cycles for drive train (e.g., motor, transmission, etc.) and energy storage (e.g., battery) that may be operated through a combined heating/cooling fluid loop are also provided. Embodiments are also directed to systems having thermal management cycles for the HVAC that is fluidly isolated, but thermally coupled to one or both of the drivetrain and energy storage components. Heating/cooling loops for these thermal management cycles may be functionally linked through one or more valves such that the fluid flow through such cycles may be combined together, isolated from each other or mixed in various desired configurations.

Aspects and embodiments of the invention provide a control system, a coolant system, a vehicle comprising a control system, a computer-implemented method and computer software as claimed in the appended claims.

According to an aspect of the present invention there is provided a control system, comprising one or more controllers, the control system comprising: input means to receive a temperature signal indicative of a temperature of a transmission associated with a traction electric machine of a vehicle, output means to output a flow control signal for controlling a flow control means to control a flow of lubricant fluid associated with the traction electric machine and the transmission through a heat exchanger, the flow control signal being indicative of a proportion of the flow of lubricant fluid through the heat exchanger and at least one bypass fluid path, respectively, wherein the at least one bypass fluid path comprises one or more conduits allowing a circulation of lubricant fluid between the electric machine and the transmission bypassing the heat exchanger, and processing means arranged to: i) control the output means to output the flow control signal in dependence on the temperature signal, ii) to determine the proportion of the flow of lubricant through the heat exchanger and the at least one bypass fluid path in dependence on the temperature signal, and iii) to control the output means to output the flow control signal in dependence on the temperature signal to cause the traction electric machine to heat the transmission. Advantageously, the transmission is caused to be heated which may improve an efficiency of the transmission. The efficiency may be improved by heating of lubricant fluid within the transmission.

The output means may be arranged to output a heat control signal for causing the electric machine to operate in a loss operating mode for heating the lubricant fluid; and the processing means may be arranged to control the output means to output the heat control signal in dependence on the temperature signal.

The processing means may be arranged to control the output means to output the heat control signal whilst the vehicle is stationary.

The processing means may be arranged to control the output means to output the flow control signal in dependence on a temperature threshold.

The processing means may be arranged to determine the proportion of the flow of lubricant fluid through the heat exchanger and the at least one bypass fluid path, respectively to maintain the temperature of the transmission (<NUM>) above the temperature threshold.

The input means may be arranged to receive a heat request signal indicative of a request for heating of one or both of a traction battery of the vehicle and a cabin of the vehicle; and the processing means may be arranged to control the output means to output the flow control signal in dependence on the heat request signal.

The control signal may cause the fluidic communication of thermal energy from a heat source directly to a transmission lubricant. Advantageously heat is more efficiently communicated to the transmission lubricant.

The processing means may be arranged to control the output means in dependence on a temperature threshold. Advantageously the temperature threshold improves an accuracy of control of the heating.

The processing means is optionally arranged to compare the temperature signal and the temperature threshold to determine whether to control the output means to output the control signal to cause heating of the transmission. Advantageously the comparison is indicative of whether to heat the transmission. In some embodiments, hysteresis is employed in the comparison. Advantageously the hysteresis may avoid frequent changes in the heating state.

The input means may be arranged to receive a journey signal indicative of a likelihood of a journey of the vehicle commencing. Advantageously control of the heating may be made in advance of a journey commencing.

The processing means is optionally arranged to control the output means to output the control signal in dependence on the journey signal to cause heating the transmission prior to the journey of the vehicle commencing. Advantageously an efficiency of the transmission may be improved at a start of the journey.

The control signal may be arranged to control one or more of pumping means and/or valve means to circulate heated fluid via the transmission heat exchanger. Advantageously one or more of pumping means and/or valve means is used to control the flow of heated fluid via the heat exchanger.

The control signal is optionally arranged to control one or more of pumping means and valve means to circulate heated fluid via a traction battery of the vehicle. Advantageously the fluid may be used to heat the traction battery to improve an efficiency of the traction battery.

According to another aspect of the present invention there is provided a coolant system for a traction electric machine of a vehicle, comprising: a heat exchanger for exchanging thermal energy between lubricant fluid and a coolant fluid; flow control means for controlling a flow of the lubricant fluid through the heat exchanger, wherein the lubricant fluid is associated with the traction electric machine and a transmission of the traction electric machine; and a control system according to any preceding claim, wherein the flow control means is arranged to receive the flow control signal from the control system and to control the flow of lubricant fluid through the heat exchanger in dependence thereon; at least one bypass fluid path for allowing at least a portion of the flow of lubricant fluid to bypass the heat exchanger, wherein the flow control means is arranged to control the proportion of the flow of lubricant fluid through the heat exchanger and the bypass fluid path respectively in dependence on the flow control signal. The coolant system may comprise a coolant fluid circuit arranged to circulate coolant fluid therethrough via the heat exchanger, wherein the coolant fluid circuit, comprises either a traction battery circuit for circulating coolant fluid in thermal communication with a traction battery, of the vehicle for heating the traction battery; or a cabin heating circuit for circulating coolant fluid in thermal communication with a cabin heater of the vehicle for heating the cabin of the vehicle.

According to another aspect of the present invention there is provided a vehicle comprising a control system as described above or a coolant system as described above.

According to yet another aspect of the present invention there is provided a method, comprising receiving, by an input means of a control system, a temperature signal indicative of a temperature of a transmission associated with a traction electric machine of a vehicle; determining, by a processing means of the control system, in dependence on the temperature signal, a proportion of the flow of lubricant fluid through a heat exchanger and at least one bypass fluid, respectively; wherein the at least one bypass fluid path comprises one or more conduits allowing a circulation of lubricant fluid between the electric machine and the transmission bypassing the heat exchanger; and controlling, by the processing means of the control system, flow of lubricant fluid associated with the traction electric machine, and a transmission of the vehicle through the heat exchanger in dependence on the temperature signal and on the determined proportion, and output means to output a flow control signal in dependence on the temperature signal to cause the traction electric machine to heat the transmission.

The proportion of the flow of lubricant fluid through the heat exchanger may be determined to maintain the temperature of the transmission above a temperature threshold.

According to a further aspect of the present invention, there is provided computer software which, when executed by a control system described herein, is arranged to perform the method described herein. Optionally, the computer software is stored on a computer readable medium.

A system is also described comprising a control system as described above, temperature sensing means arranged to output the temperature signal to the control system, the temperature signal being indicative of a temperature of at least a portion of a transmission associated with a traction electric machine of a vehicle, and fluid control means arranged to receive a control signal output by the control system, wherein the fluid control means is arranged to control fluid communication of thermal energy from a heat source to a transmission heat exchanger for heating the transmission.

The fluid control means optionally comprises a pump arranged to circulate heated fluid via the transmission heat exchanger. The fluid control means optionally comprises a valve arranged to direct the heated fluid via the transmission heat exchanger. The temperature sensing means may be thermally coupled with the transmission. Advantageously an accuracy of the temperature sensing means may be improved via the thermal coupling.

There is also described a system for an electric vehicle comprising a fluid communication system for fluidicly communicating thermal energy from a heat source to a transmission heat exchanger for heating a transmission associated with a traction inverter and traction electric machine of the vehicle, temperature sensing means arranged for outputting a temperature signal indicative of a temperature of at least a portion of the transmission, and a control system comprising an input means to receive the temperature signal, an output means to output a control signal for causing circulation of the fluid in the fluid communication system, wherein the control system is arranged to output the control signal in dependence on the temperature signal.

The transmission heat exchanger may be arranged to receive heated fluid to transfer thermal energy from the heated fluid to a lubricant of the transmission. The transmission heat exchanger optionally comprises an electric machine portion for circulating coolant fluid in thermal communication with the traction electric machine.

Optionally the fluid communication system comprises a heat source heat exchanger having first and second fluid circuits, the heat source heat exchanger being arranged to circulate fluid received from the heat source through the second fluid circuit and to communicate thermal energy from the received fluid to fluid in the first fluid circuit, wherein the fluid communication system is arranged to circulate fluid from the first fluid circuit of the heat source heat exchanger to the transmission heat exchanger.

The fluid communication system is optionally arranged to fluidicly communicate thermal energy from the heat source to a traction battery of the electric vehicle. The first fluid circuit is optionally arranged to communicate thermal energy to the traction battery. The traction battery and the transmission heat exchanger may be arranged in parallel branches of the first fluid circuit. Optionally the heat source comprises one or more of an electrical heater or a heat pump.

There is also described a control system comprising one or more controllers, for an electric vehicle, the control system comprising input means to receive a temperature signal indicative of a temperature of a transmission of the vehicle, output means to output a flow control signal for controlling a flow control means to control a flow of lubricant fluid, and processing means arranged to control the output means to output the flow control signal in dependence on the temperature signal. Advantageously, the flow of lubricant fluid is controlled to control a temperature of the transmission. The control of the temperature of the transmission may improve an efficiency of the transmission.

There is also described a control system, comprising one or more controllers, for an electric vehicle, the control system comprising input means to receive a temperature signal indicative of a temperature of a transmission associated with a traction electric machine of the vehicle, output means to output a flow control signal for controlling a flow control means to control a flow of lubricant fluid associated with the traction electric machine and the transmission through a heat exchanger, and processing means arranged to control the output means to output the flow control signal in dependence on the temperature signal. Advantageously, the flow of lubricant fluid is controlled to control a temperature of the transmission. The control of the temperature of the transmission may improve an efficiency of the transmission.

The processing means is optionally arranged to control the output means to output the flow control signal in dependence on the temperature signal to cause the traction electric machine to heat the transmission. Advantageously, heating of the transmission may improve the efficiency of the transmission. The output means may be arranged to output a heat control signal for causing the electric machine to operate in a loss operating mode for heating the lubricant fluid. Advantageously the electric machine may be caused to generate additional heat to heat the lubricant fluid, which may in turn heat the transmission. The processing means may be arranged to control the output means to output the heat control signal in dependence on the temperature signal. Advantageously, the operation of the electric machine in the loss mode may be made dependent on the temperature.

The processing means is optionally arranged to control the output means to output the heat control signal whilst the vehicle is stationary. Advantageously, the loss mode may be utilised to generate heat even when the electric machine is not used for propulsion.

The flow control signal may be indicative of a proportion of the flow of lubricant fluid through the heat exchanger and at least one bypass fluid path, respectively. Advantageously, control of the heating may be achieved by directing the lubricant fluid through the heat exchanger or the bypass fluid path. Optionally the processing means is arranged to determine the proportion of the flow of lubricant through the heat exchanger and the at least bypass fluid path in dependence on the temperature signal. Advantageously, control of the lubricant fluid through the heat exchanger or the bypass fluid path is performed dependent on the temperature. The processing means may be arranged to control the output means to output the flow control signal in dependence on a temperature threshold. Advantageously, heating of the transmission may only be performed with respect to the temperature threshold.

The processing means is optionally arranged to determine the proportion of the flow of lubricant fluid through the heat exchanger to maintain the temperature of the transmission above the temperature threshold. Advantageously, the flow of lubricant fluid is performed to maintain the temperature of the transmission. The input means may be arranged to receive a heat request signal indicative of a request for heating of one or both of a traction battery of the vehicle and a cabin of the vehicle. Advantageously, heating of the traction battery or the cabin may be requested. The processing means is optionally arranged to control the output means to output the flow control signal in dependence on the heat request signal. Advantageously, heat from the lubricant fluid may be used to satisfy the request for heating. The processing means may be arranged to control the output means to output a pump control signal to cause a pump to circulate the flow of lubricant fluid through one or both of the transmission and the traction electric machine. Advantageously, the lubricant fluid may be circulated to control the heating. The at least one bypass fluid path may comprise one or more conduits allowing a circulation of lubricant fluid between the electric machine and the transmission bypassing the heat exchanger. Advantageously, the bypass fluid path may be used to control a heat output.

There is also described a coolant system for a traction electric machine of a vehicle, comprising a heat exchanger for exchanging thermal energy between lubricant fluid and a coolant fluid, flow control means for controlling a flow of the lubricant fluid through the heat exchanger, wherein the lubricant fluid is associated with the traction electric machine and a transmission of the traction electric machine, and a control system according to any preceding claim, wherein the flow control means is arranged to receive the flow control signal from the control system and to control the flow of lubricant fluid through the heat exchanger in dependence thereon.

The coolant system may comprise at least one bypass fluid path for allowing at least a portion of the flow of lubricant fluid to bypass the heat exchanger, wherein the flow control means is arranged to control the proportion of the flow of lubricant fluid through the heat exchanger and the bypass fluid path respectively in dependence on the flow control signal. The coolant system may comprise a coolant fluid circuit arranged to circulate coolant fluid therethrough via the heat exchanger. Advantageously, the coolant fluid may exchange heat with the transmission via the heat exchanger.

The coolant fluid circuit is optionally arranged to circulate coolant fluid therethrough via an electric machine coolant portion for circulating coolant fluid therethrough in thermal communication with the traction electric machine. Advantageously, the coolant fluid may be heated via thermal communication with the electric machine. The electric machine coolant portion may comprise one or more fluid conduits in thermal communication with a casing of the traction electric machine. Advantageously, efficient thermal communication is achieved. The coolant fluid circuit optionally comprises an inverter coolant portion for circulating coolant fluid therethrough in thermal communication with an inverter associated with the traction electric machine. Advantageously, the coolant fluid may be heated via thermal communication with the inverter. The heat exchanger is optionally arranged to receive the lubricant fluid from the transmission. Advantageously, the heat exchanger communicates heat with the lubricant fluid. The coolant fluid circuit optionally comprises a traction battery circuit for circulating coolant fluid in thermal communication with a traction battery of the vehicle for heating the traction battery. Advantageously, the coolant may communicate heat with the traction battery. The coolant fluid circuit comprises a cabin heating circuit for circulating coolant fluid in thermal communication with a cabin heater of the vehicle for heating the cabin of the vehicle. Advantageously, the coolant may communicate heat for heating the cabin.

There is also described a vehicle comprising a control system as described above or a coolant system as described above.

There is also described a computer-implemented method, comprising receiving a temperature signal indicative of a temperature of a transmission associated with a traction electric machine of a vehicle, and controlling flow of lubricant fluid associated with a traction electric machine and a transmission of the vehicle through a heat exchanger in dependence on the temperature signal. The flow of lubricant fluid may be controlled in dependence on the temperature signal to cause the traction electric machine to heat the transmission. The method may comprise determining a proportion of the flow of lubricant fluid through the heat exchanger and at least one bypass fluid path, respectively, and controlling flow of lubricant fluid in dependence on the determined proportion. The proportion of the flow of lubricant fluid through the heat exchanger may be determined to maintain the temperature of the transmission above a temperature threshold.

There is also described a control system, comprising one or more controller, for an electric vehicle having a transmission associated with a traction electric machine, the control system comprising input means to receive a heat request signal indicative of a request for heating of one or more modules of the vehicle, output means to output a control signal for causing the transmission to output heat for the one or more modules of the vehicle, and processing means arranged to determine transmission heating power, and to compare the transmission heating power and electric heating power for the request for heating, wherein the processing means is arranged to control the output means to output the control signal in dependence on the comparison. Advantageously heat is output from the transmission when more efficient than utilising electrical heating.

There is also described a control system, comprising one or more controller, for an electric vehicle, the control system comprising input means (<NUM>) to receive a heat request signal (<NUM>) indicative of a request for heating of one or more modules of the vehicle, and a temperature signal indicative of a temperature of a transmission (<NUM>) associated with a traction electric machine (<NUM>) of the vehicle, output means (<NUM>) to output a control signal (<NUM>) for causing a heat exchanger (<NUM>) associated with the transmission (<NUM>) to output heat for the one or more modules of the vehicle, and processing means (<NUM>) arranged to determine transmission heating power in dependence on the temperature signal, and to compare the transmission heating power and electric heating power for the request for heating, wherein the processing means is arranged to control the output means to output the control signal in dependence on the comparison. Advantageously heat is output from the transmission when more efficient than utilising electrical heating.

The electrical heating power may be a direct electrical heating power or a heat pump heating power. Advantageously, the transmission heating power is compared against a cost of direct electrical heating or heat pump heating. The heating power may be electrical power consumption. Advantageously, the power consumption using electrical heating is considered. The control signal is a flow control signal for controlling a flow control means to control a flow of lubricant fluid associated with the traction electric machine and the transmission through the heat exchanger. Advantageously the flow of lubricant is controlled to control heat output from the transmission. The determining the transmission heating power comprises determining a current power loss of the transmission in dependence on the temperature signal. Advantageously the current power loss of the transmission considers efficiency of using the transmission to provide heat output. Determining the transmission heating power may comprise determining a minimum power loss for the transmission. Advantageously the power loss of the transmission is considered in determining whether to use the transmission as a heat source. The transmission heating power may be determined in dependence on the current power loss and the minimum power loss of the transmission. Advantageously both the current power loss and minimum power loss are considered. The processing means may be arranged to control the output means to output the control signal to reduce heat output from the heat exchanger in dependence on the comparison indicating the electrical heating power being less than the transmission heating power. Advantageously electrical heating is used when more efficient.

The processing means is optionally arranged to control the output means to output the control signal to increase heat output from the heat exchanger in dependence on the comparison indicating the transmission heating power being less than the electrical heating power. Advantageously the transmission is used as a heat source when more efficient. The processing means may be arranged to control the output means to output the control signal in a stepwise manner. Advantageously the heat output from the transmission is changed gradually or incrementally.

In said stepwise manner, the processing means may be arranged to control the output means to output the control signal indicative of an increase in heat output, and to determine the transmission heating power in dependence on a change in temperature of the transmission. Advantageously the change is temperature of the transmission is considered after each increase in heat output. The processing means may be arranged to control the output means to output the control signal to control the flow control means to increase the flow of lubricant fluid through the heat exchanger to increase the heat output. Advantageously the flow of lubricant is used to control the heat output. The processing means is arranged to control the output means to output a pump control signal to cause a pump to circulate the flow of lubricant fluid through one or both of the transmission and the traction electric machine output heat for the one or more modules of the vehicle. Advantageously the pump is controlled to circulate lubricant to thereby control heat output.

There is also described a coolant system for a traction electric machine of a vehicle, comprising a heat exchanger for exchanging thermal energy between lubricant fluid and a coolant fluid, flow control means for controlling a flow of the lubricant fluid through the heat exchanger, wherein the lubricant fluid is associated with the traction electric machine and a transmission of the traction electric machine, and a control system according to any preceding claim, wherein the flow control means is arranged to receive the control signal from the control system and to control the flow of lubricant fluid through the heat exchanger in dependence thereon. The coolant system may comprise at least one bypass fluid path for allowing at least a portion of the flow of lubricant fluid to bypass the heat exchanger, wherein the flow control means is arranged to control the proportion of the flow of lubricant fluid through the heat exchanger and the bypass fluid path respectively in dependence on the control signal.

The coolant system may comprise a coolant fluid circuit arranged to circulate coolant fluid therethrough via the heat exchanger for communicating heat to the one or more modules of the vehicle. The coolant fluid circuit is optionally arranged to circulate coolant fluid therethrough via an electric machine coolant portion for circulating coolant fluid therethrough in thermal communication with the traction electric machine. The electric machine coolant portion may comprise one or more fluid conduits in thermal communication with a casing of the traction electric machine. The coolant fluid circuit may comprise an inverter coolant portion for circulating coolant fluid therethrough in thermal communication with an inverter associated with the traction electric machine. The heat exchanger may be arranged to receive the lubricant fluid from the transmission. The one or more modules of the vehicle may comprise a traction battery of the vehicle. The coolant fluid circuit may comprise a traction battery circuit for circulating coolant fluid in thermal communication with the traction battery of the vehicle for heating the traction battery. The one or more modules of the vehicle may comprise a cabin heater and the coolant fluid circuit comprises a cabin heating circuit for circulating coolant fluid in thermal communication with the cabin heater for heating at least a portion of the cabin of the vehicle.

There is also described a computer-implemented method, comprising receiving a heat request signal indicative of a request for heating of one or more modules of the vehicle, and a temperature signal indicative of a temperature of a transmission associated with a traction electric machine of a vehicle, determining transmission heating power in dependence on the temperature signal, comparing the transmission heating power and electric heating power for the request for heating, and controlling the transmission to output heat from a heat exchanger for the one or more modules of the vehicle in dependence on the comparison. The determining the transmission heating power comprises determining a current power loss of the transmission in dependence on the temperature signal. Determining the transmission heating power may comprise determining a minimum power loss for the transmission. The transmission heating power may be determined in dependence on the current power loss and the minimum power loss of the transmission. The method may comprise controlling the transmission to increase heat output from the heat exchanger in dependence on the comparison indicating the transmission heating power being less than the electrical heating power.

There is also described computer software which, when executed by a processing means, is arranged to perform a method according to any of the aspects described above. Optionally the computer software is tangibly stored on a computer readable medium.

One or more embodiments of the disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:.

Embodiments of the present invention are provided for controlling a temperature of one or more components of a vehicle. Some embodiments of the present invention are provided for heating a transmission system associated with a vehicle. Other embodiments of the present invention are provided for heating other modules of a vehicle. The heating may be achieved by utilising heat from an electric machine of the vehicle, such as a traction electric machine thereof.

With reference to <FIG>, a system <NUM> is illustrated which comprises a control system <NUM> according to an embodiment of the present invention. The control system <NUM> may be formed by one or more electronic controller <NUM>. Each controller <NUM> may comprise a respective processing means <NUM>, such as an electronic processing device <NUM> or computer processor. The processing device <NUM> is arranged to operably execute computer-readable instructions which may be stored in a memory means <NUM> formed by one or more memory devices <NUM> forming a memory <NUM> which is communicatively coupled to the processing device <NUM>.

The system <NUM> further comprises an electric machine <NUM> operable as a traction electric machine <NUM> and a transmission <NUM> associated therewith for an electric vehicle, such as a vehicle <NUM> illustrated in <FIG>. In use, the traction electric machine <NUM> provides torque to one or more wheels of the vehicle <NUM> via the transmission <NUM>. The electric machine <NUM> is associated with a unit <NUM> which comprises traction power electronics, such as an inverter, for providing an electrical supply to the traction electric machine <NUM>. The transmission <NUM> provides at least one gear ratio between an output of the traction electric machine <NUM> and the one or more wheels of the vehicle. In some embodiments, the traction electric machine <NUM> and the transmission <NUM> may be integrated into a single unit or housing to provide an electric drive unit (EDU) for the vehicle. The traction electric machine <NUM> and the transmission <NUM> may be associated with one or more wheels of the vehicle. In some embodiments, the traction electric machine <NUM> and the transmission <NUM> are associated with an axle of the vehicle arranged to provide torque to first and second wheels associated with the axle, which may be each disposed at respective ends of the axle. However it will be appreciated that the EDU may be associated with only one wheel of the vehicle.

The transmission <NUM> has a lubricant fluid for lubricating components of the transmission <NUM>. The traction electric machine <NUM> and the transmission <NUM> may share the lubricant fluid. That is, the lubricant fluid may be circulated between the traction electric machine <NUM> and the transmission <NUM>, such as when formed as the EDU. In some embodiments, a temperature sensing means <NUM>, such a temperature sensing device <NUM>, which may be a thermocouple or similar, is arranged to measure a temperature of the transmission <NUM>. In some embodiments, the temperature sensing device <NUM> may be arranged to measure the temperature of the lubricant fluid in particular. In some embodiments, the temperature sensing device <NUM> may be associated with a sump of the transmission <NUM> or EDU to measure a temperature of the lubricating fluid within the sump, although other arrangements may be envisaged. The temperature sensing device <NUM> operatively outputs a temperature signal <NUM> indicative of the temperature of the transmission <NUM> associated with the traction electric machine <NUM>.

The controller <NUM> comprises an input means <NUM> and an output means <NUM>. The input means <NUM> may comprise an electrical input <NUM> of the controller <NUM> The output means <NUM> may comprise an electrical output <NUM> of the controller <NUM>. The input <NUM> is arranged to receive the temperature signal <NUM>. The temperature signal <NUM> is an electrical signal which is indicative of the temperature of the transmission <NUM> associated with the traction electric machine <NUM> of the vehicle. The temperature may be an internal temperature of the transmission <NUM>. In some embodiments, the temperature is a temperature of the lubricating fluid of the transmission <NUM>. However it will be appreciated that in other embodiments the temperature signal <NUM> may be derived from other measurements or signals to be indicative of the temperature of the transmission <NUM>.

The output <NUM> of the controller <NUM> is arranged to operably output a control signal <NUM> under control of the processing device <NUM>. The control signal <NUM> is for controlling the temperature of the transmission <NUM>. In particular, in embodiments of the invention, the control signal <NUM> is for causing heating of the transmission <NUM>, as will be explained.

The control signal <NUM>, in some embodiments, is arranged to cause fluidic communication of thermal energy from a heat source for heating the transmission <NUM>. By fluidic communication it is meant that the thermal energy, or heat, is communicated by one or more fluids i.e. that the same fluid may not necessarily carry the thermal energy from the heat source to the transmission <NUM>. In some embodiments, the thermal energy may be carried or exchanged between fluids via one or more heat exchangers. However in some embodiments it will be appreciated that the fluid may be heated directly by a heat source such as a heater and the fluid communicated to directly heat the transmission <NUM>.

In the embodiment shown in <FIG>, the system <NUM> comprises a transmission heat exchanger <NUM> which is thermally coupled with the transmission <NUM>. The transmission heat exchanger <NUM> is arranged to receive a fluid therein, referred to as a coolant fluid, with it being understood that the coolant fluid is a fluid which may be heated to provide thermal energy to the transmission <NUM>. Thus the term coolant does not necessarily imply that the fluid is for cooling. The coolant fluid may be a suitable fluid having a heat capacity greater than water or other desirable characteristics for communicating thermal energy. Furthermore, it will be appreciated that via suitable control means such as valves the coolant fluid may, at other times during operation, be used to cool the transmission <NUM>. The coolant fluid is communicated to the transmission heat exchanger <NUM> via a coolant circuit <NUM>. Although not shown in <FIG>, it will be realised that the coolant circuit <NUM> may comprise both a supply and return coolant conduits for communicating heated coolant fluid to the transmission heat exchanger <NUM> and returning coolant having less or reduced thermal energy after having heated the transmission <NUM>. The system <NUM> comprises a flow control means <NUM> which is arranged to control the flow of coolant via the coolant circuit <NUM> to the transmission heat exchanger <NUM>. The flow control means <NUM> is arranged to receive the control signal <NUM> output from the controller <NUM> to control the flow of coolant to the transmission heat exchanger <NUM>. In particular, the flow control means <NUM> is arranged to control the flow of heated coolant fluid to the transmission heat exchanger <NUM> to operably cause heating of the transmission <NUM> by the heated coolant fluid.

The flow control means <NUM> may comprise one or more valve means and pumping means, such as one or more valves and one or more pumps associated with the coolant circuit <NUM>. The one or more valves and one or more pumps control, in dependence on the control signal <NUM>, the flow of heated coolant fluid to the transmission heat exchanger <NUM>. In response to the control signal <NUM> the flow control means <NUM> is arranged to circulate heated fluid to the transmission heat exchanger <NUM> for heating the transmission <NUM>. As will be explained, in some embodiments, the control signal <NUM> is arranged to control one or more of pumping means and valve means to circulate heated fluid via a traction battery of the vehicle <NUM>.

The processor <NUM> is arranged to receive temperature data in the form of the temperature signal <NUM> provided to the input <NUM> of the controller <NUM> and to control the output <NUM> of the controller <NUM> to output the control signal <NUM> in dependence on the temperature signal <NUM>. The control signal <NUM> may be referred to as a flow control signal <NUM> in some embodiments.

In some embodiments, the processor <NUM> is arranged to control the output <NUM> in dependence on a temperature threshold. Data indicative of the temperature threshold may be stored in the memory <NUM> of the controller <NUM>. The temperature threshold is indicative of a temperature at or below which the transmission <NUM> is to be heated for improving efficiency of the transmission <NUM> communicating torque to the one or more wheels of the vehicle. For example the temperature threshold may be indicative of a temperature such as <NUM> or <NUM> at or below which transmission <NUM> should be heated, although other temperatures may be selected.

The processing means <NUM> is arranged, in some embodiments, to compare the temperature indicated by the temperature signal <NUM> and the temperature threshold to determine whether to control the output <NUM> to output the control signal <NUM> to cause heating of the transmission <NUM>. In some embodiments, hysteresis is employed by the processing means <NUM> in the comparison whereby two temperature thresholds are utilised, one of which indicates a temperature to commence heating of the transmission <NUM> and one of which indicates a temperature to cease heating of the transmission to advantageously prevent frequent switching of the heating of the transmission <NUM>. In some embodiments, the processing means <NUM> of the controller <NUM> is arranged to determine whether the temperature of the transmission <NUM> is at or below the temperature threshold and to control heating of the transmission <NUM> dependent thereon, prior to a journey of the vehicle commencing i.e. that is before the traction electric machine <NUM> and the transmission <NUM> are used to provide motive or traction torque for the vehicle.

In some embodiments the input <NUM> of the controller <NUM> is arranged to receive a journey signal <NUM> indicative of a likelihood of a journey of the vehicle commencing. The journey signal <NUM> may be provided from another controller of the vehicle, such as a body control module (BCM). The journey signal <NUM> may be generated in dependence on one or more events which indicate that the vehicle may be shortly used for a journey. The journey signal <NUM> may be generated in dependence on, for example, one or more apertures such as doors of the vehicle <NUM> being unlocked or opened. The journey signal <NUM> may be generated in dependence on a location of a user of the vehicle, where the location may be determined in dependence on a location of a mobile device of the user, such as a telephone or wireless keyfob associated with the vehicle. When the user is determined to be approaching the vehicle, the journey signal <NUM> is provided to the controller <NUM> in dependence thereon. In some embodiments, the journey signal <NUM> may be generated in dependence on a diary or schedule associated with the user being indicative of an upcoming event, such as a regular journey or scheduled meeting, for example, requiring a journey to be made by the vehicle. In dependence on the time of the expected journey, the journey signal <NUM> is generated at a predetermined time ahead of the expected journey. The predetermined time may be, for example, <NUM> or <NUM>, <NUM> minutes or <NUM> hour or more, such as <NUM> hours in advance of a start time of the expected journey. Thus the processor <NUM> is arranged to control the output <NUM> to output the control signal <NUM> in dependence on the journey signal <NUM> to cause heating the transmission <NUM> prior to the journey of the vehicle commencing. In this way, when the vehicle of the journey commences the transmission <NUM> may be advantageously heated to improve efficiency of the vehicle <NUM>.

<FIG> illustrates a method <NUM> according to an embodiment of the invention. The method <NUM> is a method of controlling the temperature of the transmission <NUM> associated with the traction electric machine <NUM> of the vehicle. The method <NUM> may be performed in the system <NUM> described above with reference to <FIG>. To aid understanding of the method <NUM>, reference is also made to <FIG> which illustrates a temperature <NUM> of the transmission <NUM> over time, as will be explained.

The method <NUM> comprises a block <NUM> of determining whether a journey signal <NUM> has been received. The journey signal <NUM> is illustrated in <FIG> as active high, although other configurations may be envisaged. If the journey signal <NUM> has been received the method moves to block <NUM>. If the journey signal <NUM> hasn't been received, the method <NUM> loops back to block <NUM> i.e. doesn't progress until the journey signal <NUM> is received. Once the journey signal <NUM> has been received, the method progresses. Referring to <FIG>, the journey signal <NUM> is received at time t<NUM>.

The method <NUM> comprises a block of determining <NUM> the temperature <NUM> of the transmission <NUM> associated with the traction electric machine <NUM> of the vehicle <NUM>. In particular, block <NUM> comprises receiving the temperature signal <NUM> indicative of the temperature of the transmission <NUM>. The temperature signal <NUM> may be received at the input <NUM> of the controller <NUM> illustrated in <FIG> from the temperature sensing device <NUM> associated with the transmission <NUM>. The temperature signal <NUM> may be indicative of the temperature of the lubricant fluid within the transmission <NUM>. As indicated in <FIG>, at a start of the method i.e. t=<NUM> the transmission <NUM> may have a first temperature <NUM>, such as a temperature of <NUM> in a relatively cold environment of the vehicle.

The method <NUM> comprises a block <NUM> of determining whether the temperature <NUM> of the transmission <NUM> is less than a predetermined temperature threshold <NUM> as illustrated in <FIG>. In <FIG> at time t<NUM> when block <NUM> is performed (or substantially immediately thereafter) the temperature <NUM> of the transmission <NUM> is less than the temperature threshold <NUM>. In this case, the method <NUM> moves to block <NUM>. If, however, the temperature of the transmission <NUM> is greater than or equal to the threshold <NUM>, the method <NUM> returns to block <NUM>, as in <FIG>, or may end.

In block <NUM> the transmission <NUM> is heated. In particular, the lubricant fluid within the transmission <NUM> is heated in some embodiments. Block <NUM> in some embodiments comprises causing fluidic communication of thermal energy from a heat source to the heat exchanger <NUM> associated with the transmission <NUM> for heating the transmission <NUM>. The heat source may in some embodiments be a high-voltage (HV) heater of the vehicle. By HV it is understood that the heater has a voltage of greater than 50V such as 250V or more. The heater voltage may be around 400V in some embodiments. In the system of <FIG>, block <NUM> comprises the controller <NUM> outputting the control signal <NUM>, indicated as signal <NUM> in <FIG>, to the flow control means <NUM> to allow heated fluid to communicate the thermal energy to the transmission heat exchanger <NUM> i.e. to heat the lubricant fluid of the transmission <NUM> via the heat exchanger <NUM>. As can be appreciated from <FIG>, in dependence on the control signal <NUM>, the temperature <NUM> of the transmission <NUM> is caused to rise over time as thermal energy is communicated to the transmission <NUM>, particularly to the lubricant fluid therein. As the journey signal <NUM> is generated in advance of a journey of the vehicle beginning, the transmission <NUM> may be heated, at least partially, whilst the vehicle is stationary i.e. in advance of the journey. In <FIG>, the journey signal <NUM> may correspond to doors of the vehicle being unlocked and thus may remain active during at least part of the journey of the vehicle. In the method <NUM> of <FIG>, the method returns to block <NUM> to again check the temperature of the transmission <NUM>. Once the temperature of the transmission <NUM> reaches the temperature threshold <NUM>, the heating of the transmission <NUM> may be discontinued. The heating may be discontinued by de-asserting the control signal <NUM> as in <FIG> at time t<NUM>. If the traction electric machine <NUM> is being used to deliver torque through the transmission <NUM> at this point, it will be appreciated that the temperature of the transmission <NUM> may be maintained or may continue to rise even absent the fluidic heating of the transmission <NUM>, although not shown in <FIG>. It will be appreciated that block <NUM> may be periodically performed during use of the vehicle i.e. whilst the vehicle is in motion or during the journey to ensure the temperature of the transmission <NUM> is maintained above the temperature threshold <NUM>.

<FIG> is a diagram of a thermal management system <NUM> of a vehicle according to an embodiment of the invention. The thermal management system <NUM> of <FIG> is associated with a plurality of EDUs <NUM>, <NUM>, in particular first and second EDUs <NUM>, <NUM> in the illustrated embodiment, each comprising a traction electric machine <NUM> associated with a transmission <NUM>. Each EDU <NUM>, <NUM> may provide torque to a respective wheel or axle of the vehicle. However it will be appreciated that the vehicle may comprise one, or more than two, EDUs.

The thermal management system <NUM> of <FIG> comprises a first fluidic or coolant circuit <NUM> and a second fluidic or coolant circuit <NUM>. The first coolant circuit <NUM> is associated with the EDUs <NUM>, <NUM>. The second coolant circuit <NUM> is associated with a cabin of the vehicle. The first and second coolant circuits <NUM>, <NUM> may exchange thermal energy via a heat exchanger <NUM> as will be explained. In <FIG> fluid conduits carrying warm coolant, cool coolant and fluid conduits which may not be used are indicated with dashing.

The first coolant circuit <NUM> may also be associated with electrical module(s) of the EDUs <NUM>, <NUM> such as an inverter of the traction electric machine <NUM> of each EDU <NUM>, <NUM> as shown in <FIG>. The first coolant circuit <NUM> is associated with the one or more EDUs <NUM>, <NUM> and in the embodiment of <FIG> a traction battery <NUM> of the vehicle. Thus in some embodiments of the invention heating may be provided to the traction battery <NUM>. The first coolant circuit <NUM> may also be associated with one or more electrical module(s) <NUM> of the vehicle associated with a HV electrical system of the vehicle, such as one or more of an on-board charger (OBC), DC-DC converter <NUM> etc. It will be understood that by associated, it is meant that the first coolant circuit <NUM> is thermally coupled or communicative to transfer thermal energy to/from the respective component to coolant flowing in the coolant circuit <NUM>.

It will be appreciated from <FIG> that the first and second EDUs <NUM>, <NUM> are present in a first branch <NUM> or loop of the first coolant circuit <NUM> in some embodiments, the traction battery <NUM> is present in a second branch <NUM> of the first coolant circuit <NUM>. The first and second branches <NUM>, <NUM> may be arranged in parallel configuration as in <FIG>. Each of the first and second branches <NUM>, <NUM> of the first coolant circuit <NUM> may comprise a respective pump <NUM>, <NUM> for pumping coolant fluid there-through. In this way, coolant fluid may be selectively circulated through each of the first and second branches <NUM>, <NUM> of the first coolant circuit <NUM> by the respective pump <NUM>, <NUM>. A control signal may be provided to each of the pumps <NUM>, <NUM> for controlling the pump to circulate coolant fluid through the respective branch <NUM>, <NUM>. A valve <NUM> is present in the first coolant circuit <NUM> which selectively joins the first and second branches <NUM>, <NUM>. In particular, in some embodiments, the valve <NUM> has first and second inlet ports to receive coolant from each of the first and second branches <NUM>, <NUM> and an outlet port to allow egress of coolant fluid from the valve <NUM> to return to the heat exchanger <NUM>. In some embodiments, the valve <NUM> may be replaced by a three-way junction to receive coolant from the first and second branches <NUM>, <NUM> and to output coolant fluid to the heat exchanger <NUM>. In the embodiment shown in <FIG>, the valve <NUM> comprises one or more selectively openable output ports, indicated as optional flows in <FIG>, which allow coolant fluid to be directed to an inlet side of the EDUs <NUM>, <NUM>.

The first coolant circuit <NUM> comprises the heat exchanger <NUM>. The heat exchanger <NUM> is a coolant-to-coolant to heat exchanger <NUM>. The heat exchanger <NUM> is arranged to allow heat transfer between the first coolant circuit <NUM> and the second coolant circuit <NUM>. The first coolant circuit <NUM> passes through a first side of the heat exchanger <NUM> and the second coolant circuit <NUM> passes through a second side of the heat exchanger <NUM>, thereby enabling an exchange of thermal energy between the first and second coolant circuits <NUM>, <NUM>. As will be described, the heat exchanger <NUM> may be used to transfer heat from the second coolant circuit <NUM> to the first coolant circuit <NUM> to heat one or both of the traction battery <NUM> and the one or more EDUs <NUM>, <NUM>. The heat exchanger <NUM> is arranged in the first coolant circuit <NUM> to receive coolant fluid having passed through the one or more EDUs <NUM>, <NUM> and/or the traction battery <NUM>. The heat exchanger <NUM> is arranged to heat the coolant fluid in the first coolant circuit <NUM> for return to the one or more EDUs <NUM>, <NUM> and/or the traction battery <NUM>.

The first coolant circuit <NUM> may comprise a cooler or chiller <NUM>. The chiller <NUM> may be arranged alongside i.e. in parallel with the heat exchanger <NUM>. The chiller <NUM> is arranged to receive coolant fluid having passed through the one or more EDUs <NUM>, <NUM> and/or the traction battery <NUM>. The chiller <NUM> may act as a heat exchanger for a HVAC system of the vehicle, as will be explained with reference to <FIG>.

The second coolant circuit <NUM> is, in some embodiments, a climate control coolant circuit associated with an occupant cabin of the vehicle. In some embodiments of the invention, heat is sourced from the second coolant circuit <NUM> to the first coolant circuit to heat one or both of one or more of the EDUs <NUM>, <NUM> and the traction battery <NUM> of the vehicle. In particular, as discussed above, the heat is sourced from the second coolant circuit <NUM> to heat the transmission <NUM> of one or more EDUs <NUM>, <NUM> of the vehicle to thereby improve an efficiency of the vehicle.

The second coolant circuit <NUM> comprises a heater <NUM> for heating the coolant within the second coolant circuit <NUM> and a pump <NUM> for circulating the coolant within the second coolant circuit <NUM>. The heater <NUM> may be an electrically powered heater. Coolant within the second coolant circuit <NUM> is circulated between the heater <NUM> and the heat exchanger <NUM>, such that thermal energy is provided by the heater <NUM> to the first coolant circuit <NUM>. It will be appreciated that, in some embodiments, the heater <NUM> may directly heat coolant fluid within the first coolant circuit <NUM>. The heater <NUM> may be a HV heater <NUM> of the vehicle.

The second coolant circuit <NUM> may comprise a heater core <NUM> for receiving coolant in the second coolant circuit <NUM> heated by the heater <NUM> and heating air in the occupant cabin of the vehicle, such as may be circulated through the heater core <NUM> by one or more fans. The second coolant circuit <NUM> may, in some embodiments, further comprise a condenser <NUM>. The condenser <NUM> is associated with another fluid circuit, such as circuit <NUM> in <FIG>, and is arranged to condense refrigerant within the other fluid circuit <NUM> to heat coolant fluid within the second coolant circuit <NUM>. Thus the condenser <NUM> can heat the second coolant circuit <NUM> from the refrigerant in the other fluid circuit <NUM>.

In some embodiments, the second coolant circuit <NUM> comprises a valve <NUM>. The valve <NUM> is operable selectively to divert the flow of coolant within the second coolant circuit <NUM> between a return conduit <NUM>, indicated as an optional flow in <FIG>, for returning coolant having passed through the heater core <NUM> directly to the heater <NUM> and a flow path <NUM> to the heat exchanger <NUM>. The valve <NUM> may be operable responsive to the control signal <NUM> discussed above, such that when the control signal <NUM> is indicative of heating of the transmission <NUM> the coolant flow in the second coolant circuit <NUM> is directed to flow via the heat exchanger <NUM>. In this way, when heating of the transmission <NUM> is not required, coolant is not circulated through the heat exchanger <NUM> to thereby improve efficiency of cabin heating. Coolant fluid in the second coolant circuit <NUM> having passed through the heat exchanger <NUM> returns along fluid path <NUM> to be re-heated by the heater <NUM>, in the embodiment shown via the condenser <NUM>.

In some embodiments, the second coolant circuit <NUM> comprises a pump <NUM> for circulating coolant fluid. In some embodiments, the system <NUM> comprises a degas tank <NUM> which is present in one or both of the first and second coolant circuits <NUM>, <NUM> to allow for degassing of the coolant fluid. The first coolant circuit <NUM> may comprise in some embodiments a radiator <NUM> for use as a low temperature radiator <NUM>. Coolant may be directed to the radiator <NUM> by the valve <NUM>.

It will be appreciated that through control of the valve <NUM> in the second coolant circuit <NUM> to direct coolant fluid to the heat exchanger <NUM>, and particularly control of one or both of the pumps <NUM>, <NUM> coolant fluid in the first coolant circuit <NUM> may be heated and used to heat one or both of the EDUs <NUM>, <NUM> and traction battery <NUM>. In particular, in some embodiments of the invention, heated coolant fluid may selectively or controllably be provided, i.e. at desired times, to the EDUs <NUM>, <NUM>. In particular, the transmission <NUM> may be heated from the coolant fluid to heat the lubricant fluid therein, which may reduce a viscosity of the lubricant fluid, to improve an efficiency of the EDU <NUM>, <NUM>.

<FIG> illustrates a heat transfer apparatus <NUM> according to an embodiment of the present invention. The heater transfer apparatus <NUM> may be used in the system of <FIG> associated with one or each EDU <NUM>, <NUM>. The heat transfer apparatus <NUM> may be used to thermally couple the first coolant circuit <NUM> with each EDU <NUM>, <NUM>. The heat transfer apparatus <NUM> may be used for heat transfer between coolant fluid and the transmission <NUM> associated with the traction electric machine <NUM>. The embodiment of heat transfer apparatus <NUM> shown in <FIG> is arranged to circulate coolant fluid between the transmission <NUM> and the traction electric machine <NUM> of one or both of the EDUs <NUM>, <NUM>. In some embodiments, the heat transfer apparatus <NUM> is arranged to circulate coolant fluid to an electrical module of the EDU <NUM> such as the inverter. The heat transfer apparatus <NUM> may be comprised in the first coolant circuit <NUM> shown in <FIG>.

The heat transfer apparatus <NUM> comprises an inlet <NUM> and an outlet <NUM> for receiving and outputting coolant fluid, respectively, flowing around the first coolant circuit <NUM>. The apparatus <NUM> comprises an electric machine portion <NUM> for circulating coolant fluid in thermal communication with the traction electric machine <NUM> and a transmission portion <NUM> in thermal communication with the transmission <NUM>. The electric machine portion <NUM> comprises a fluid jacket <NUM> for the electric machine <NUM> which circulates coolant around at least a portion of an exterior casing of the traction electric machine <NUM>. In the embodiment shown the fluid jacket <NUM> is formed by a plurality of turns of conduit in cylindrical configuration for receiving the traction electric machine <NUM> there-between. The transmission portion <NUM> comprises a heat exchanger for exchanging thermal energy between the coolant flowing through the apparatus <NUM> around the first coolant circuit <NUM> and lubricant fluid within the transmission <NUM>. In some embodiments, lubricant fluid within the transmission <NUM> is circulated through a portion of the heat exchanger <NUM> to efficiently exchange thermal energy with the coolant in the first coolant circuit <NUM>. In some embodiments, as described below, the EDU <NUM>, <NUM> comprises a pump circulating the lubricant fluid between the traction electric machine <NUM> and the transmission which is arranged to circulate the lubricant fluid through the heat exchanger <NUM>. In some embodiments, the heat transfer apparatus <NUM> comprises an inverter portion <NUM> for thermally coupling to an inverter arranged to provide an electrical supply to the traction electric machine <NUM>. As discussed above, in particular, the heat transfer apparatus <NUM> is useful for receiving heated coolant fluid to heat, in particular, the transmission <NUM> associated with the traction electric machine <NUM>. Heating the transmission <NUM>, and lubricant fluid therein, may improve an efficiency of torque generation by the traction electric machine <NUM> to thereby reduce energy consumption from the traction battery <NUM> of the vehicle.

<FIG> illustrates a system <NUM> according to another embodiment of the disclosure which comprises a control system <NUM> according to another embodiment of the present invention. The system <NUM> may be used to assist controlling a temperature of a transmission associated with a traction electric machine of the vehicle. In particular, the system <NUM> may be useful to assist heating of the transmission <NUM>, such as prior to a journey of the vehicle. However the system <NUM> may be useful to assist heating other components of modules of the vehicle, as will be explained.

The control system <NUM> may be formed by one or more electronic controllers <NUM>. Each controller <NUM> may comprise a respective processing means <NUM>, such as an electronic processing device <NUM> or computer processor. The processing device <NUM> is arranged to operably execute computer-readable instructions which may be stored in a memory means <NUM> formed by one or more memory devices <NUM> forming a memory <NUM> which communicatively coupled to the processing device <NUM>. As in the embodiment described with reference to <FIG>, the controller <NUM> comprises an input means <NUM> and an output means <NUM>. The input means <NUM> may comprise an electrical input <NUM> of the controller <NUM>. The output means <NUM> may comprise an electrical output <NUM> of the controller <NUM>. The system of <FIG> is arranged to control a temperature of an electric drive unit (EDU) <NUM>, such as described above, of a vehicle. The temperature of the EDU <NUM> is controlled by controlling a flow of lubricant fluid within the EDU <NUM>, as will described. In some embodiments, the EDU <NUM> is controlled to act as a heat source. Advantageously a traction electric machine <NUM> of the EDU <NUM> may be used to assist in heating the transmission <NUM> of the EDU <NUM> by controlling the flow of lubricant fluid therein.

As in the system described above with reference to <FIG> and shown in <FIG>, the EDU <NUM> comprises an electric machine <NUM> operable as a traction electric machine <NUM> and a transmission <NUM> associated therewith for an electric vehicle. In use, the traction electric machine <NUM> provides torque to one or more wheels of the vehicle via the transmission. The transmission <NUM> provides at least one gear ratio between an output of the traction electric machine <NUM> and the one or more wheels of the vehicle. In some embodiments, the traction electric machine <NUM> and the transmission <NUM> may be integrated into a single housing to form the EDU <NUM> i.e. as an integral unit. The EDU <NUM> may be associated with a heat transfer apparatus <NUM>, such as the heat transfer apparatus <NUM> illustrated in <FIG>, for transferring thermal energy to/from EDU <NUM>. The heat transfer apparatus <NUM> comprises a heat exchanger <NUM>, <NUM> and <NUM> for transferring thermal energy between the EDU <NUM> and a received coolant fluid <NUM>, such that coolant fluid <NUM> output from the heat transfer apparatus <NUM> has a different level of thermal energy, or temperature, than the received coolant fluid <NUM>. That is, the coolant fluid may not necessarily cool the EDU <NUM> but may be used, at least at some points in time, to heat the EDU <NUM> as described above. Thermal energy may be transferred from one or more of the electric machine via fluid jacket <NUM>, transmission from the transmission portion <NUM> such as from transmission lubricant fluid and the inverter <NUM> when the EDU <NUM> is operated as a heat source. In this way, heat may be selectively transferred away from the EDU <NUM> to heat other parts of the vehicle as will be explained.

Lubricant fluid is used with the EDU <NUM> to lubricate the transmission <NUM>. The lubricant fluid may also be used to lubricate and/or cool the electric machine <NUM>. In some embodiments, lubricant fluid within the EDU <NUM> is circulated via one or more of a rotor and stator windings of the traction electric machine <NUM>. In this way, as well as from a casing of the traction electric machine <NUM>, the lubricant fluid is heated by the traction electric machine <NUM>.

One or more fluid communication paths are present within the EDU <NUM> between the traction electric machine <NUM> and the transmission <NUM>, such that they may share the lubricant fluid i.e. lubricant fluid may be circulated there-between. That is, the lubricant fluid may be circulated between the traction electric machine <NUM> and the transmission <NUM> via the one or more fluid communication paths or conduits.

The input <NUM> of the controller <NUM> is arranged to receive a temperature signal <NUM> indicative of a temperature of the transmission of the EDU <NUM>. In some embodiments, the temperature signal <NUM> may be derived from one or more measurements, particularly temperature measurements of components of the vehicle such as the traction electric machine or of a casing of the EDU <NUM>. However in some embodiments, a temperature sensing means <NUM>, such a temperature sensing device is <NUM>, which may be a thermocouple or similar, is associated with the EDU <NUM> and may be arranged to measure a temperature of the transmission of the EDU <NUM>. In some embodiments, the temperature sensing device <NUM> may be associated with a sump of the transmission or EDU <NUM> to measure a temperature of the lubricant fluid within the sump, although other arrangements may be envisaged. The temperature sensing device <NUM> operatively outputs the temperature signal <NUM> to the input <NUM> of the controller <NUM>. The input may also be arranged to receive a journey signal <NUM> as described above.

The output <NUM> of the controller <NUM> is arranged to operably output one or more control signals <NUM>, <NUM> under control of the processing device <NUM>. The one or more control signals <NUM>, <NUM> are for controlling the temperature of the EDU <NUM>. In particular, in some embodiments of the invention, the one or more control signals <NUM>, <NUM> comprises a flow control signal <NUM> for controlling a flow of lubricant fluid through the heat exchanger <NUM> associated with the EDU <NUM>, as will be explained. The control of the flow of lubricant through the heat exchanger <NUM> may be used to assist in heating the transmission <NUM> of the EDU <NUM>. The control of the flow of lubricant may alternatively or additionally be used to assist heating of other components of the vehicle <NUM>.

The one or more control signals <NUM>, <NUM> may comprise a heat control signal <NUM> for causing the traction electric machine <NUM> to operate in a powerloss operating mode. In the powerloss operating mode, the traction electric machine <NUM> and its associated traction power electronics <NUM>, such as the inverter, are arranged to generate excess heat. By excess it is meant more heat than necessary to generate traction torque. In other words, the traction electric machine <NUM> may be caused to operate inefficiently to generate additional heat by the heat control signal <NUM>. Furthermore, in the powerloss mode, when the traction electric machine <NUM> is not required to produce traction torque, the traction electric machine <NUM> may generate heat for use in heating other components or modules of the vehicle. The heat may be used to heat the transmission <NUM> of the EDU <NUM>. The heat may be used to heat other components of the vehicle. It will be appreciated that the electric machine <NUM> may receive other control signals, such as indicative of a torque demand.

<FIG> illustrates a thermal control system <NUM> according to another embodiment of the disclosure. The thermal control system <NUM> is for controlling the temperature of the EDU <NUM>. The thermal control system <NUM> may, in use, assist in heating the transmission <NUM> of the EDU <NUM>. The thermal control system <NUM> may be used to achieve heating of other components of the vehicle <NUM> such as one or both of a cabin of the vehicle and a traction battery of the vehicle, although other components may be heated by the thermal control system <NUM>.

The thermal control system <NUM> comprises the heat transfer apparatus <NUM> discussed above in relation to <FIG>. The heat transfer apparatus <NUM> may be that described above with reference to <FIG> where like reference numerals indicate corresponding parts. The heat transfer apparatus <NUM> comprises the inlet <NUM>, <NUM> and the outlet <NUM>, <NUM> discussed above for receiving and outputting coolant fluid, respectively to allow coolant fluid to flow there-through. The heat transfer apparatus <NUM> is arranged to receive a flow of coolant fluid at the inlet <NUM> and to output coolant fluid from the outlet <NUM> which may have a different temperature than the received coolant fluid. Thus the coolant fluid may remove thermal energy from the EDU <NUM>, which may be used to heat other components of the vehicle.

The heat transfer apparatus <NUM> comprises a heat exchanger, denoted by arrow <NUM> in <FIG>, described above with reference to <FIG>. The heat exchanger <NUM> comprises a coolant portion or circuit <NUM> for exchanging thermal energy between the coolant fluid circulated therethrough and a lubricant portion or circuit <NUM> of the heat exchanger <NUM> i.e. the two circuits <NUM>, <NUM> together form the heat exchanger <NUM> for exchanging heat between the coolant fluid and the lubricant fluid in the of the EDU <NUM>.

As described above in relation to <FIG> and shown in <FIG>, in some embodiments the heat transfer apparatus <NUM>, <NUM> comprises the electric machine portion <NUM> and the inverter portion <NUM>. It will be noted that the order of the inverter portion <NUM>, coolant portion <NUM> of the heat exchanger <NUM> and the electric machine portion <NUM> between the inlet <NUM> and outlet <NUM> may be different from that illustrated in <FIG> and is not restricted in this way. Thus the coolant fluid passing through the heat transfer apparatus <NUM>, <NUM> may be heated, at least in part, via a casing of the traction electric machine <NUM> and an inverter associated with the traction electric machine <NUM>.

The EDU <NUM>, shown schematically in more detail in <FIG>, comprises a lubricant module <NUM> having a lubricant pump <NUM> and a valve <NUM>, and also including the lubricant circuit <NUM> of the heat exchanger <NUM>. The lubricant module <NUM> is arranged to circulate lubricant fluid around the EDU <NUM>, particularly between the traction electric machine <NUM> and the transmission <NUM> of the EDU <NUM>. The valve <NUM> is arranged to control a flow of lubricant fluid within the EDU <NUM>, and in particular a flow of lubricant fluid associated with the traction electric machine <NUM> and the transmission <NUM> through the heat exchanger <NUM>.

In some embodiments, lubricant fluid is collected via a pickup <NUM> from within the EDU <NUM>, such as from a sump thereof, and pumped by the pump <NUM> via a fluid path <NUM> to the valve <NUM>. The valve <NUM> is arranged to control, in dependence on the control signal <NUM>, hereinafter referred to as a valve control signal <NUM>, whether the lubricant fluid is circulated to one or both of the traction electric machine <NUM> and the transmission <NUM> via the lubricant circuit <NUM> of the heat exchanger <NUM>.

The valve <NUM>, in a first configuration, directs lubricant fluid along a first path <NUM> through the lubricant circuit <NUM> of the heat exchanger <NUM>. In a second configuration the valve <NUM> is arranged to direct the lubricant fluid via a second path or bypass fluid path <NUM> to omit circulation via the lubricant circuit <NUM> of heat exchanger <NUM>. That is, in the second configuration the lubricant fluid is circulated by the pump <NUM> within the EDU <NUM> without passage via the heat exchanger <NUM>. In this way, thermal loss of the lubricant fluid is reduced in the second configuration i.e. the lubricant fluid may heat faster, or retain heat, when not circulating via the heat exchanger <NUM>. When the valve <NUM> is configured to direct the lubricant fluid via the first path through the lubricant circuit <NUM> of the heat exchanger <NUM>, when the lubricant fluid is warm, the coolant fluid flowing through the other side of the heat exchanger <NUM> may be heated by the lubricant fluid, which is consequently reduced in temperature or cooled. The heated coolant fluid may be used to heat other components or modules of the vehicle <NUM> as will be explained.

It will be appreciated that, in some embodiments, intermediate configurations of the valve <NUM> may be indicated by the valve control signal <NUM> wherein lubricant fluid is communicated in respective proportions via the first and second fluid paths <NUM>, <NUM>. For example, the valve control signal <NUM> may control the valve to partially direct fluid, for example <NUM>% or <NUM>% of the lubricant fluid pumped by the pump <NUM>, to the second, bypass, fluid path <NUM>. In the illustrated embodiment, lubricant fluid from the lubricant circuit of the heat exchanger <NUM> and the bypass fluid path <NUM> is circulated to one or both of the traction electric machine <NUM> and the transmission of the EDU <NUM>. In this way, the temperature of the lubricant fluid may be controlled. When waste heat is available from the EDU <NUM> the valve control signal <NUM> may direct at least a part of the excess heat from the EDU <NUM> partially or completely through the first path <NUM> allowing lubricant fluid to circulate through the heat exchanger <NUM>.

As noted above, the traction electric machine <NUM> may be controlled to generate heat, either without generating torque, or to generate additional heat i.e. additional to that which would normally be generated whilst the traction electric machine <NUM> generates torque. Such heat generation may be caused by appropriate control of one or more electrical currents within the traction electric machine <NUM>.

Whilst the vehicle is stationary, without the traction electric machine <NUM> generating traction torque, the traction electric machine <NUM> may be controlled to generate excess or waste heat by only applying current to one or more selected windings of the traction electric machine <NUM>. In some embodiments, only a d-axis stator current (Id) of the traction electric machine <NUM> is energised to generate heat without also generating torque i.e. the rotor is not caused to rotate. The Id current may be a DC current applied to the stator windings. In other embodiments, an AC current is applied to Id or Iq to create a rotating current vector independent of a position of a rotor of the traction electric machine <NUM>.

When the traction electric machine <NUM> is being used to generate torque i.e. the rotor is rotating, one or more currents flowing within the traction electric machine <NUM> may be controlled to generate additional, waste, heat at least some of which is transferred to the lubricant fluid. This is achieved by increasing the scaled speed which represents the speed of the electric machine with respect to the Direct Current-Link voltage of the inverter. This results in a non-optimal current set point for the requested torque. This non-optimal current set point results in higher losses being produced by the electric machine and inverter for the same operating point for torque and speed.

The generation of heat, or additional heat, by the traction power electronics <NUM>, such as the inverter, and traction electric machine <NUM> may be performed in dependence on the heat control signal <NUM>. The heat control signal <NUM> may cause the traction inverter and traction electric machine <NUM> to operate in the powerloss mode as described above. Thus it can be appreciated that the traction inverter and traction electric machine <NUM> may be controlled by the heat control signal <NUM> to generate heat i.e. to convert electrical energy to thermal energy either whilst the vehicle is stationary (without also generating traction torque) or whilst the vehicle is in motion. The thermal energy from the traction inverter and traction electric machine <NUM> may be used to heat the transmission <NUM>, particularly before a journey commences, or other modules of the vehicle.

<FIG> illustrates a method <NUM> according to an embodiment of the disclosure.

The method <NUM> is a method of controlling a temperature of the EDU <NUM>. In particular, the method <NUM> is a method of heating a transmission <NUM> of a vehicle <NUM>. The transmission <NUM> may be heated prior to a journey of the vehicle commencing i.e. whilst the vehicle is stationary. The transmission may be heated by controlling a flow of lubricant between the traction electric machine <NUM> and the transmission <NUM> of the EDU <NUM>.

The method <NUM> comprises a block <NUM> of determining whether a journey signal <NUM> indicative of a likelihood of a journey of the vehicle <NUM> has been received. If the journey signal <NUM> hasn't been received, the method <NUM> loops back to block <NUM> i.e. doesn't progress until the journey signal <NUM> is received. Further information about the journey signal is provided above in relation to <FIG>. If the journey signal <NUM> is received the method <NUM> moves to block <NUM>.

The method comprises a block <NUM> of determining a temperature of the transmission <NUM> associated with the traction electric machine <NUM> of the vehicle. In particular, some embodiments of block <NUM> comprises receiving the temperature signal <NUM>. The temperature signal <NUM> may be indicative of the temperature of a lubricating fluid within the EDU <NUM> or the transmission <NUM>. The temperature signal <NUM> may be received at the input <NUM> of the controller <NUM> illustrated in <FIG> from the temperature sensing device <NUM> associated with the EDU <NUM>.

The method <NUM> comprises a block <NUM> of determining whether the temperature indicated by the temperature signal <NUM> is less than a predetermined temperature threshold, such as the temperature threshold <NUM> illustrated in <FIG>. If the temperature is less than the temperature threshold, the method <NUM> moves to block <NUM>. If, however, the temperature of the transmission <NUM> is greater than or equal to the temperature threshold the method returns to block <NUM>, or may end.

In block <NUM>, the valve <NUM> of the EDU <NUM> is controlled to improve heating of the EDU <NUM>, in particular the transmission <NUM> of the EDU <NUM> which may improve efficiency of the traction electric machine <NUM> providing motive torque for the vehicle. The valve <NUM> is controlled by the controller <NUM> outputting the valve control signal <NUM> to control a proportion of the flow of lubricant fluid within the EDU <NUM> through the heat exchanger <NUM> and the at least one bypass fluid path <NUM>. In block <NUM>, the valve control signal <NUM> is indicative of the valve <NUM> being configured to control a distribution of fluid between the first fluid path <NUM> i.e. via the lubricant circuit of the heat exchanger <NUM> and via the bypass fluid path <NUM> omitting the heat exchanger <NUM>.

Flow of lubricant fluid via the heat exchanger <NUM> transfers thermal energy from the EDU <NUM> to the coolant fluid flowing through the coolant circuit <NUM> of the heat exchanger <NUM>. In some embodiments, lubricant fluid flow through the bypass fluid path <NUM> may be used to achieve heating of the lubricant fluid by reducing thermal loss to the coolant fluid. The transfer of thermal energy to the coolant fluid i.e. away from the EDU <NUM> may be used to control the temperature of the EDU <NUM>, in particular to prevent the temperature of the EDU <NUM> becoming too high. Furthermore, in some embodiments, the thermal energy transferred to coolant fluid i.e. to the first coolant fluid circuit <NUM> shown in <FIG> may be used to heat other parts of the vehicle, such as the traction battery <NUM> and or a cabin of the vehicle as will be described. That is, the EDU <NUM> may be used as a heat source. In such embodiments, the valve <NUM> may be used to control an amount of thermal energy transferred away from the EDU <NUM> i.e. to control the temperature of the EDU <NUM>.

In block <NUM> the transmission <NUM> is heated. In particular, the lubricant fluid within the transmission <NUM> is heated. Block <NUM> in some embodiments comprises causing the traction inverter and traction electric machine <NUM> to generate heat for heating the transmission <NUM> of the EDU <NUM>. As described above, in block <NUM> the controller <NUM> is arranged to output the heat control signal <NUM>. As described above, the heat control signal <NUM> is arranged to cause the traction electric machine <NUM> to operate in the powerloss mode to generate heat, either whilst the vehicle is stationary i.e. without generating traction torque, or whilst the vehicle is in motion i.e. while the traction electric machine <NUM> generates traction torque. The heat generated by the traction inverter and traction electric machine <NUM> is communicated to the lubricant fluid within the EDU <NUM>, such as by the coolant fluid of the traction inverter <NUM> and traction electric machine stator <NUM> being in thermal communication with the heat exchanger <NUM>, as well as the transmission lubricant fluid being in direct thermal communication with windings and/or the rotor of the traction electric machine <NUM>. It will also be appreciated that the transmission <NUM> may be heated by heated coolant fluid as in the embodiment described above.

In order to improve heating of the transmission <NUM>, in block <NUM> the controller <NUM> is arranged to output the valve control signal <NUM> to control the flow of lubricant fluid to flow at least partly via the bypass fluid path <NUM>. In this way, the lubricant fluid retains heat generated by the traction electric machine <NUM> within the EDU <NUM>. Thus the flow of lubricant fluid within the EDU <NUM> may be increased in dependence on a temperature of the transmission <NUM> being lower, in particular the temperature being below the temperature threshold described above.

As in the embodiment illustrated in from <FIG>, in dependence on the heating of the transmission, the temperature <NUM> of the transmission <NUM> begins to rise over time as thermal energy is communicated to the transmission <NUM>, particularly to the lubricant fluid therein from the traction electric machine <NUM>. As the journey signal <NUM> is generated in advance of a journey of the vehicle beginning, the transmission <NUM> may be heated, at least partially, whilst the vehicle <NUM> is stationary. As described above, the journey signal <NUM> may be generated in dependence on doors of the vehicle being unlocked or an occupant of the vehicle being proximal to the vehicle. The journey signal <NUM> may remain active during at least a part of a journey of the vehicle. The temperature of the transmission <NUM> may be controlled during the journey of the vehicle <NUM>.

In the method <NUM> of <FIG>, the method returns to block <NUM> to check the temperature of the transmission <NUM>. Once the temperature of the transmission <NUM> reaches the temperature threshold, the heating may be discontinued i.e. the powerloss mode may be ceased. The valve <NUM> may be controlled to direct the flow of lubricant fluid via the first fluid path and the lubricant circuit <NUM> of the heat exchanger <NUM>. Thus the temperature of the EDU <NUM> may be controlled i.e. maintained within a working temperature band above the temperature threshold.

<FIG> is a diagram of a thermal management system <NUM> of a vehicle according to another embodiment of the disclosure. The system <NUM> comprises like components to the system <NUM> discussed above in relation to <FIG> and therefore, for clarity, discussion of components having like reference numerals will be omitted.

In addition, the system <NUM> of <FIG> comprises heat pump circuit <NUM> comprising a compressor <NUM>. Refrigerant fluid is arranged to circulate around the heat pump circuit <NUM>. The refrigerant passes through the chiller <NUM> which acts as a heat exchanger with the first coolant circuit <NUM> having coolant fluid circulating through in thermal communication with the EDU <NUM> i.e. via the heat exchanger <NUM>. The refrigerant may be a multiphase or single phase fluid.

The compressor <NUM> is arranged to receive refrigerant from the chiller <NUM>. The compressor <NUM> may receive the refrigerant in the form of a chilled gas from the chiller <NUM>. The compressor <NUM> compresses the refrigerant and provides the compressed refrigerant the condenser <NUM>. The condenser <NUM> is arranged to heat the coolant fluid in the second coolant circuit <NUM> prior to the heater <NUM>. In this way, heat is provided to the second coolant circuit <NUM> for heating the occupant cabin of the vehicle <NUM> from the heat pump circuit <NUM>. The condenser <NUM> condenses the gas from the compressor <NUM>, which may cause the gas to return to a liquid state of the refrigerant. The compressor <NUM> is thus arranged to change or upgrade a grade of heat of the refrigerant in the heat pump circuit <NUM>, as will be explained further below. That is, the compressor <NUM> is operative to increase exergy of the fluid in the heat pump circuit <NUM>.

In some embodiments, the system <NUM> comprises a receiver-drier (R/D) <NUM>. As will be appreciated, the R/D <NUM> may retain moisture and contaminants in fluid circulated therethrough and assist in condensation of the refrigerant in circuit <NUM>. In some embodiments, the refrigerant circuit <NUM> may comprise pump for pumping fluid therethrough.

Therefore it can be appreciated that the coolant flowing in the first coolant circuit <NUM> is in thermal communication via heat exchanger (chiller) <NUM> with the refrigerant circuit <NUM> including compressor <NUM>. The heat exchanger thus acts as a heat source to the refrigerant circuit <NUM>. Thus the grade of heat may be controlled via refrigerant circuit <NUM>.

In this way, coolant in the first coolant circuit <NUM> heated via the EDU <NUM> may be caused to heat the coolant flowing in the second coolant circuit <NUM> for heating the occupant cabin of the vehicle <NUM>.

<FIG> illustrates a system <NUM> which comprises a control system <NUM> according to another embodiment of the disclosure. Like reference numerals to the system <NUM> illustrated in <FIG> have been used where appropriate for clarity. The reader is directed to the description above associated with <FIG> for description of like-numbered components. The system <NUM> may be used to assist controlling a temperature of one or more components or modules of the vehicle <NUM>. In particular, the system <NUM> may be useful to assist heating of one or more components or modules of the vehicle <NUM>, such as prior to a journey of the vehicle. The one or more components or modules of the vehicle <NUM> may be those external to the EDU <NUM> and heat transfer apparatus <NUM>. The one or more components or modules of the vehicle <NUM> may comprise a traction battery of the vehicle <NUM> or an occupant compartment or cabin of the vehicle <NUM>, with it will being appreciated that embodiments of the invention may be used to heat other components or modules.

The system <NUM> shown in <FIG> comprises a controller <NUM> having an input means <NUM> which, as described above, may comprise an electrical input <NUM> of the controller <NUM>. The input <NUM> is arranged to receive a heat request signal <NUM> indicative of a request for heating of the one or more components or modules of the vehicle <NUM>. The input <NUM> also receives the temperature signal <NUM> indicative of the temperature of the transmission <NUM> of the EDU <NUM> as described above. Although the controller <NUM> is not shown as receiving the journey signal <NUM> described above, it will be understood that this is merely for ease of representation and that the controller <NUM> may perform one or more steps or processes in dependence on the journey signal <NUM>.

The controller <NUM> has an output means <NUM> which, as described above, may comprise an electrical output <NUM> of the controller <NUM>. The output <NUM> is arranged to output a control signal <NUM> for causing a heat exchanger <NUM> associated with one or both of the traction inverter and traction electric machine <NUM> and the transmission <NUM> of the EDU <NUM> to output heat for the one or more modules of the vehicle <NUM>. As will be explained, in some embodiments, the control signal <NUM> is a flow control signal <NUM> for controlling a flow control means to control a flow of lubricant fluid associated with the traction electric machine <NUM> and the transmission <NUM> through the heat exchanger <NUM>, such that the heat exchanger <NUM> outputs heat for the one or more modules of the vehicle <NUM>. The flow control means may be the valve <NUM> of the EDU <NUM> discussed above.

The controller <NUM> is arranged to perform a method <NUM>, <NUM> according to an embodiment of the disclosure such as illustrated in one or both of <FIG> and <FIG> as will be described. In embodiments of the invention, the controller <NUM> is arranged to compare a heating power of the EDU <NUM> and electric heating power to determine whether heating for the one or more modules of the vehicle is to be provided from the EDU <NUM> or from an electric powered source of heating i.e. which may consume electrical power from one or more batteries of the vehicle. The determination of whether heating is to be provided from the EDU <NUM> may comprise a determination of whether sufficient heat is available from the EDU <NUM>. In some embodiments, as will be explained, the determination comprises determining a relative expense or cost of providing the heat from the EDU <NUM> or from the electrical source of heating. The cost of providing the heat from the EDU <NUM> may comprise consideration of additional electrical power consumption from the traction electric machine <NUM> of the EDU <NUM> as the temperature of the EDU <NUM>, and particularly lubricant fluid in the transmission <NUM>, is reduced consequent to providing the heat from the EDU <NUM>.

The methods <NUM>, <NUM> illustrated in <FIG> and <FIG> form a method of determining whether to use heat from the EDU <NUM> or electrical heating for one or more modules of the vehicle. The method <NUM> illustrated in <FIG> may be performed in some embodiments of block <NUM> of the method <NUM> illustrated in <FIG>. The methods <NUM>, <NUM> may be computer-implemented such as by the controller <NUM> of the control system <NUM> illustrated in <FIG>.

Referring to <FIG>, block or step <NUM> comprises determining whether a heat request signal <NUM> is received. The heat request signal <NUM> may be received at the input <NUM> of the controller <NUM>. The heat request signal <NUM> is indicative of a request for heating of one or more modules of the vehicle. The heat request signal <NUM> may be provided, for example, from a controller associated with the traction battery <NUM> of the vehicle <NUM> in dependence on a determination of a temperature of the traction battery <NUM>. For example, determining that the temperature of the traction battery <NUM> is below a temperature threshold. The heat request signal <NUM> may be provided from a controller associated with a heating system of the vehicle <NUM>, such as an occupant cabin heating system, such as in HVAC system of the vehicle <NUM>. The request <NUM> may be provided from the controller in dependence on a user input or a determination that a temperature of the occupant cabin is below a threshold which may have been set by an occupant of the vehicle <NUM>. Other sources of the heat request signal <NUM> may be envisaged.

In step <NUM> if the heat request signal <NUM> is not received, the method <NUM> may end or, alternatively, the method loops or pauses at step <NUM> until the heat request signal <NUM> is received. When the heat request signal is received the method <NUM> moves to block <NUM>.

Block <NUM> of the method <NUM> comprises determining whether heat is available <NUM> from the EDU <NUM> for the heat request i.e. to provide heat to the one or more modules of the vehicle <NUM>. The heat available from the EDU <NUM> may be excess or waste heat generated by the traction electric machine <NUM> providing traction torque via the transmission <NUM>. Alternatively the waste heat may be from the traction electric machine <NUM> operating in the powerloss mode whilst operating traction torque. In block <NUM>, if it is determined that heat is not available from the EDU <NUM>, the method moves to block <NUM> where heat for the one or more modules of the vehicle, such as the traction battery <NUM> or occupant cabin of the vehicle <NUM> is provided from an electric-powered heat source. The electric-powered heat source may comprise direct electric heating i.e. wherein heat is generated direct from the electric source such as via one or more heating elements to convert electricity to heat.

The method <NUM> illustrated in <FIG> may be performed in some embodiments of step <NUM> to determine whether heat is available <NUM> from the EDU <NUM>.

Referring to <FIG>, the method <NUM> comprises a block <NUM> of determining a temperature of at least a portion of the EDU <NUM>. The determination in block <NUM> may be determining a temperature T of the transmission <NUM> of the EDU <NUM>. Block <NUM> may comprise receiving the temperature signal <NUM> indicative of the temperature of the transmission <NUM>. In the method <NUM>, a transmission heating power is determined in dependence on the temperature T of the transmission <NUM>.

The method <NUM> comprises a block <NUM> of determining a power demand from the EDU. The power demand from the EDU <NUM> is the power requested from the EDU <NUM> at a current point in time. The power demand from the EDU <NUM> may be an amount of power the EDU <NUM> is being requested to deliver or produce. The power demand may be indicative of an amount of power provided by an inverter associated with the traction electric machine <NUM> at the current point in time for providing traction torque for the vehicle <NUM>. The power may be determined based on an electrical current and voltage output by the invertor.

In block <NUM> a powerloss of the EDU <NUM> is determined. The powerloss is a powerloss of the EDU <NUM> at the temperature T and the current point in time. The powerloss is the power lost by the EDU <NUM> due to inefficiency at the temperature T. In particular, the powerloss of the EDU <NUM> results particularly from the powerloss of the transmission <NUM> of the EDU <NUM> at the temperature T. The powerloss of the transmission <NUM> may arise particularly from the lubricant fluid within the transmission <NUM>. Thus in block <NUM> a current power loss of the transmission <NUM> is determined in dependence on the temperature signal <NUM> indicative of the temperature T.

In block <NUM> a minimum powerloss of the EDU <NUM> is determined. The minimum powerloss is a minimum powerloss of the transmission <NUM> of the EDU <NUM> in some embodiments. The minimum powerloss is a minimum possible powerloss of the EDU <NUM>. The minimum possible powerloss is a minimum power lost by the EDU <NUM> e.g. at an optimum or maximally efficient operating temperature. The minimum power loss may be determined according to f(η,T) where f is a function, η is indicative of efficiency of the EDU <NUM> at the temperature T. The efficiency of the EDU <NUM> is a function of the efficiency of components thereof, such as the traction inverter, traction electric machine <NUM>, transmission <NUM> components thereof such as pumps etc..

In block <NUM> a value is determined indicative of an amount of power available from the EDU <NUM> for heating the one or more modules of the vehicle <NUM>. The value may be referred to as Δpowerloss according to Δpowerloss=powerloss-min_powerloss where powerloss is that determined in block <NUM> and min_powerloss is that determined in block <NUM>. The Δpowerloss is referred to as Phi3 in block <NUM> i.e. Δpowerloss=Phi3. Thus Phi3 represents the transmission heating power i.e. an amount of power available from the EDU <NUM> for heating.

In block <NUM> a comparison is made between the transmission heating power and electric heating power required for the request for heating the one or more modules of the vehicle <NUM>. The electrical heating power may comprise one or both of direct electrical heating power and indirect electrical heating power, such as required to power a heat pump heating system of the vehicle <NUM>.

In block <NUM> Phi1 represents electrical power required for direct electrical heating i.e. using one or more heating elements for directly converting electrical power to heat. The one or more heating elements may be associated with the traction battery <NUM> or may be part of a HV coolant heater of the vehicle, for example. In some embodiments, the conversion of electrical power to heat may be assumed to performed at a <NUM>:<NUM> ratio, where 1kW of electrical energy produces 1kW of heat energy for simplicity although other conversion factors may be used. Thus electrical power may be considered to be Phi1=ΔPowerElec1 where =ΔPowerElec1 is electrical power for direct heating.

In some embodiments Phi2 may represent electrical power required to increase or upgrade a grade of heat available, as will be explained, for example using a heat pump. In some embodiments, the electrical power taken to upgrade the grade of heat available may be a predetermined ratio which may be greater than <NUM>:<NUM> such as <NUM>:<NUM> or <NUM>:<NUM> for example where 1kW of electrical energy produces 2kW, <NUM> or 5kW of heat energy. Thus Phi2=ΔPowerElec2 where =ΔPowerElec2 is electrical power for indirect heating i.e. using a heat pump.

In block <NUM> it is determined whether the power from the EDU <NUM> is less than the electrical heating power. In other words, whether the cost of providing the heat from the EDU <NUM> is less than the cost of providing the heat from an electrical source, which may comprise either direct or indirect electrical heating. It will be appreciated that utilising heat from the EDU <NUM> may reduce an efficiency of the EDU <NUM> and therefore the EDU <NUM> consumes more power to provide traction torque for the vehicle <NUM>. Thus in some embodiments of step <NUM> it is determined whether Ph1 or Phi2 is greater than Phi3 i.e. whether it is less costly, in terms of electrical energy consumed, to provide heat from the EDU <NUM>. If Phi3 is less than Phi1 or Phi2 then the method <NUM> moves to block <NUM> where heat is provided from the EDU <NUM>. If, however, Phi3 is greater than Phi1 or Phi2 then the method moves to block <NUM> where heat provided from the EDU <NUM> is reduced, or maintained at zero if no heat is currently being provided from the EDU <NUM> for heating other modules of the vehicle <NUM>.

In block <NUM> heat output from the heat exchanger <NUM> is increased. The heat output from the heat exchanger <NUM> is increased consequent on the comparison indicating the transmission heating power being less than the electrical heating power i.e. that less electrical power is required to use heat from the EDU <NUM> than to produce heat either directly or indirectly.

Block <NUM> may comprise the controller <NUM> outputting the control signal <NUM> to increase the heat output. In some embodiments, where the control signal <NUM> is a flow control signal <NUM>, the flow control signal <NUM> is arranged to control the valve <NUM> to direct an increased flow of lubricant fluid through one or more channels of the lubricant circuit <NUM>, such that the lubricant fluid is directed through the heat exchanger <NUM>, as illustrated in <FIG>, to output heat for heating the one or more modules of the vehicle <NUM>. In some embodiments, the control of the valve <NUM> may comprise opening the valve <NUM>, although it will be appreciated this depends on the arrangement of valve <NUM> and conduits within the EDU <NUM>.

In block <NUM> heat output from the heat exchanger <NUM> is reduced. The heat output from the heat exchanger <NUM> is reduced consequent on the comparison indicating the electrical heating power being less than the transmission heating power i.e. that less electrical power is required to produce heat either directly or indirectly, rather than using heat from the EDU <NUM>. Block <NUM> may comprise the controller outputting the control signal <NUM> to reduce the heat output. In some embodiments, where the control signal <NUM> is a flow control signal <NUM>, the flow control signal is arranged to control the valve <NUM> to direct an increased flow of lubricant fluid through one or more channels of the bypass fluid path <NUM>, such that the lubricant fluid bypasses the heat exchanger <NUM> as illustrated in <FIG>.

In one or both of blocks <NUM> and <NUM>, the control of heat output may be performed in a stepwise manner. In some embodiments, the controller <NUM> is arranged to control the output means <NUM> to output the control signal <NUM> in a stepwise manner. The stepwise manner comprises increasing or decreasing the output in steps less than a maximum change in heat output. In some embodiments, blocks <NUM>, <NUM> comprise changing a position of the valve <NUM>, i.e. opening or closing the valve <NUM>, by a predetermined amount or percentage of maximum control of the valve <NUM>. For example, the predetermined percentage may be <NUM> or <NUM>% i.e. the valve may change position in block <NUM> by <NUM>% to increase output in the stepwise manner.

Following a change in heat output in block <NUM> or <NUM>, the method <NUM> may repeat from block <NUM> to determine the transmission <NUM> heating power in dependence on a change in temperature of the transmission <NUM>. Since providing heat from the EDU <NUM> reduces a temperature of the EDU <NUM>, or the temperature of the EDU may rise, after blocks <NUM>, <NUM> the method <NUM> may return to block <NUM> to determine a current temperature of the EDU <NUM>.

In some embodiments, block <NUM> may comprise controlling a pump to circulate the flow of lubricant fluid through one or both of the transmission <NUM> and the traction electric machine <NUM> output heat for the one or more modules of the vehicle via the heat exchanger <NUM>.

Returning to <FIG>, block <NUM> comprises determining a grade of heat (GoH) or exergy of the available heat, such as from the EDU <NUM>. As will be appreciated, exergy is indicative of an amount of useful heat energy available. The determination of the GoH or exergy may be made in dependence on a temperature of the heat available from the EDU <NUM>, such as a temperature of coolant fluid heated after passing through the heat exchanger associated with the EDU <NUM>. The exergy may be calculated as Ex=S(T-T<NUM>) where S is entropy as a function of a temperature of heat energy T and T<NUM> is ambient temperature. If, for example, it was determined in the method <NUM> at t<NUM> that 5kW of heat energy is available i.e. 5000J/s at a temperature of <NUM> when ambient temperature is <NUM> (<NUM>), the GoH is calculated as (<NUM>-<NUM>)/<NUM>=<NUM>, whereas at t<NUM> 5kW of heat energy is available i.e. 5000J/s at a temperature of <NUM> then GoH=<NUM>.

In block <NUM> it is determined whether the GoH is adequate to provide heating to the one or more modules of the vehicle. The determination in block <NUM> may be made by comparing the GoH determined in step <NUM> with a threshold. The threshold may be selected according to the module of the vehicle to which heat is to be supplied. For example, a threshold associated with the traction battery <NUM> may be different than a threshold associated with the HVAC system of the vehicle <NUM>. If the GoH is not adequate i.e. is less than the threshold, the method <NUM> moves to block <NUM>. In block <NUM> the GoH of the available heat may be increased, such as by compressing heated refrigerant having passed through the heat exchanger <NUM>. The compression may be provided by the compressor <NUM> of the heat pump circuit <NUM> described above. Steps <NUM>-<NUM> are repeated in the method <NUM> until the GoH is adequate i.e. at least the threshold in step <NUM>, wherein the method <NUM> moves to step <NUM>. In step <NUM> the available heat is used to heat the one or more modules of the vehicle to at least partly satisfy the heat demand requested in step <NUM>.

As noted above, the one or more modules of the vehicle may comprise the traction battery <NUM> of the vehicle <NUM>. The traction battery <NUM> may be heated by the coolant fluid flowing through the branch <NUM> of the first coolant circuit <NUM>. The occupant cabin of the vehicle <NUM> may be heated by heating coolant fluid flowing through the second coolant circuit <NUM> as described above.

Claim 1:
A control system (<NUM>), comprising one or more controllers (<NUM>), for an electric vehicle, the control system comprising:
input means (<NUM>) to receive a temperature signal indicative of a temperature of a transmission (<NUM>) associated with a traction electric machine (<NUM>) of the vehicle (<NUM>);
output means (<NUM>) to output a flow control signal for controlling a flow control means to control a flow of lubricant fluid associated with the traction electric machine and the transmission (<NUM>) through a heat exchanger, the flow control signal being indicative of a proportion of the flow of lubricant fluid through the heat exchanger and at least one bypass fluid path, respectively; wherein the at least one bypass fluid path comprises one or more conduits allowing a circulation of lubricant fluid between the electric machine and the transmission (<NUM>) bypassing the heat exchanger; and
processing means (<NUM>) arranged to i) control the output means to output the flow control signal in dependence on the temperature signal, ii) to determine the proportion of the flow of lubricant through the heat exchanger and the at least one bypass fluid path in dependence on the temperature signal, and iii) to control the output means (<NUM>) to output the flow control signal in dependence on the temperature signal to cause the traction electric machine to heat the transmission.