Liquid cooled current sensor assemblies

This disclosure is directed to power systems for transferring power between electrical components. An exemplary power system includes a first electrical component (e.g., an inverter system) having a current sensor assembly for detecting current flowing between the first electrical component and a second electrical component (e.g., an electric motor) in order to more reliably manage and control operation of the second electrical component. The current sensor assembly may include an integrated cooler that includes an internal cooling circuit configured to circulate coolant for cooling one or more bus bars of the current sensor assembly.

TECHNICAL FIELD

This disclosure relates to power systems, and more particularly to power systems that include liquid cooled current sensor assemblies.

BACKGROUND

Electrified vehicles can be driven by one or more battery powered electric motors. Conventional motor vehicles, by contrast, rely exclusively on the internal combustion engine to propel the vehicle.

A high voltage battery pack typically powers the electric motor of electrified vehicles. An inverter system converts direct current (DC) power from the high voltage battery pack to alternating current (AC) power for powering the electric motor. The inverter system typically includes current sensors for detecting current flowing between the inverter system and the electric motor in order to more reliably manage and control operation of the electric motor.

SUMMARY

A power system according to an exemplary aspect of the present disclosure includes, among other things, a first electrical component, a second electrical component, and a current sensor assembly adapted to monitor a flow of current between the first electrical component and the second electrical component. The current sensor assembly includes a current sensor case, a bus bar extending through the current sensor case, a cooler positioned against the current sensor case, and a cooling circuit arranged inside the cooler and configured for circulating a coolant for cooling the bus bar.

In a further non-limiting embodiment of the foregoing power system, the first electrical component is an inverter system and the second electrical component is an electric motor.

In a further non-limiting embodiment of either of the foregoing power systems, the bus bar includes a first end portion that extends through a first side of the current sensor case and a second end portion that extends through a second side of the current sensor case.

In a further non-limiting embodiment of any of the forgoing power systems, the bus bar includes a mid-section that connects between the first end portion and the second end portion. The bus bar include a bend that positions the first end portion at an angle relative to the mid-section.

In a further non-limiting embodiment of any of the forgoing power systems, the angle is about 90 degrees.

In a further non-limiting embodiment of any of the forgoing power systems, the cooler is positioned against and interfaces relative to a top surface of the current sensor case.

In a further non-limiting embodiment of any of the forgoing power systems, a surface of the cooler includes an indentation sized to accommodate a first end portion of the bus bar that extends through the current sensor case.

In a further non-limiting embodiment of any of the forgoing power systems, a thermal interface material is disposed between the first end portion of the bus bar and the surface of the cooler.

In a further non-limiting embodiment of any of the forgoing power systems, the surface of the cooler is disposed between the first end portion of the bus bar and the cooling circuit.

In a further non-limiting embodiment of any of the forgoing power systems, the cooling circuit of the cooler includes an inlet port, a first cooling channel, a second cooling channel, and an outlet port.

In a further non-limiting embodiment of any of the forgoing power systems, a dividing wall is disposed between the first cooling channel and the second cooling channel.

In a further non-limiting embodiment of any of the forgoing power systems, multiple dividing walls are disposed between the first cooling channel and the second cooling channel.

In a further non-limiting embodiment of any of the forgoing power systems, the inlet port and the outlet port are located at opposite ends of the cooler.

In a further non-limiting embodiment of any of the forgoing power systems, the inlet port and the outlet port are located at adjoining walls of the cooler.

In a further non-limiting embodiment of any of the forgoing power systems, an electrified vehicle includes a power system having a first electrical component, a second electrical component, and a current sensor assembly adapted to monitor a flow of current between the first electrical component and the second electrical component. The current sensor assembly includes a current sensor case, a bus bar extending through the current sensor case, a cooler positioned against the current sensor case, and a cooling circuit arranged inside the cooler and configured for circulating a coolant for cooling the bus bar.

A method according to another exemplary aspect of the present disclosure includes, among other things, communicating a coolant through an inlet port of a cooler of a current sensor assembly, directing the coolant from the inlet port to a cooling circuit located inside the cooler, and circulating the coolant through the cooling circuit to remove heat from a bus bar of the current sensor assembly. The bus bar extends through a current sensor case that interfaces with the cooler.

In a further non-limiting embodiment of the foregoing method, the coolant includes oil or glycol.

In a further non-limiting embodiment of either of the foregoing methods, the method includes expelling the coolant from the cooling circuit through an outlet port of the cooler.

In a further non-limiting embodiment of any of the foregoing methods, the inlet port receives the coolant in series with a cooler of an inverter system.

In a further non-limiting embodiment of any of the foregoing methods, the inlet port receives the coolant in parallel with a cooler of an inverter system.

DETAILED DESCRIPTION

This disclosure is directed to power systems for transferring power between electrical components. An exemplary power system includes a first electrical component (e.g., an inverter system) having a current sensor assembly for detecting current flowing between the first electrical component and a second electrical component (e.g., an electric motor) in order to more reliably manage and control operation of the second electrical component. The current sensor assembly may include an integrated cooler that includes an internal cooling circuit configured to circulate coolant for cooling one or more bus bars of the current sensor assembly. These and other features of this disclosure are described in greater detail below.

FIG.1schematically illustrates a powertrain10for an electrified vehicle12. Although depicted as a hybrid electric vehicle (HEV), it should be understood that the concepts described herein are not limited to HEVs and could extend to other electrified vehicles, including, but not limited to, plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), fuel cell vehicles, etc.

In an embodiment, the powertrain10is a power-split powertrain system that employs first and second drive systems. The first drive system includes a combination of an engine14and a generator18(i.e., a first electric machine). The second drive system includes at least a motor22(i.e., a second electric machine), the generator18, and a battery pack24. In this example, the second drive system is considered an electric drive system of the powertrain10. The first and second drive systems are each capable of generating torque to drive one or more sets of vehicle drive wheels28of the electrified vehicle12. Although a power-split configuration is depicted inFIG.1, this disclosure extends to any hybrid or electric vehicle including full hybrids, parallel hybrids, series hybrids, mild hybrids, or micro hybrids.

The engine14, which may be an internal combustion engine, and the generator18may be connected through a power transfer unit30, such as a planetary gear set. Of course, other types of power transfer units, including other gear sets and transmissions, may be used to connect the engine14to the generator18. In an embodiment, the power transfer unit30is a planetary gear set that includes a ring gear32, a sun gear34, and a carrier assembly36.

The generator18can be driven by the engine14through the power transfer unit30to convert kinetic energy to electrical energy. The generator18can alternatively function as a motor to convert electrical energy into kinetic energy, thereby outputting torque to a shaft38connected to the power transfer unit30. Because the generator18is operatively connected to the engine14, the speed of the engine14can be controlled by the generator18.

The ring gear32of the power transfer unit30may be connected to a shaft40, which is connected to vehicle drive wheels28through a second power transfer unit44. The second power transfer unit44may include a gear set having a plurality of gears46. Other power transfer units may also be suitable. The gears46transfer torque from the engine14to a differential48to ultimately provide traction to the vehicle drive wheels28. The differential48may include a plurality of gears that enable the transfer of torque to the vehicle drive wheels28. In an embodiment, the second power transfer unit44is mechanically coupled to an axle50through the differential48to distribute torque to the vehicle drive wheels28.

The motor22can also be employed to drive the vehicle drive wheels28by outputting torque to a shaft52that is also connected to the second power transfer unit44. In an embodiment, the motor22and the generator18cooperate as part of a regenerative braking system in which both the motor22and the generator18can be employed as generators to output electrical power. For example, the motor22and the generator18can each output electrical power to the battery pack24.

The battery pack24is an exemplary electrified vehicle battery. The battery pack24may be a high voltage traction battery pack that includes a plurality of battery arrays25(i.e., battery assemblies or groupings of battery cells57) capable of outputting electrical power to operate the motor22, the generator18, and/or other electrical loads of the electrified vehicle12for providing power to propel the vehicle drive wheels28. Other types of energy storage devices and/or output devices could also be used to electrically power the electrified vehicle12.

FIG.2schematically illustrates an exemplary power system56. The power system56could be part of the powertrain10of the electrified vehicle12ofFIG.1, for example. However, the teachings of this disclosure may be applicable to any power system for any application.

In an embodiment, the power system56includes an inverter system54(i.e., a first electrical component), which is sometimes referred to as an inverter system controller (ISC), an electric motor22(i.e., a second electrical component), a terminal block assembly58, and a current sensor assembly64. Together, the terminal block assembly58and the current sensor assembly64may establish a connector assembly for electrically coupling the inverter system54and the electric motor22. Although this disclosure describes electrically coupling an electric motor and an inverter system, the terminal block and current sensor assemblies of this disclosure could be used to electrically couple any electrical components that operate over an alternating current bus within a power system.

The terminal block assembly58may electrically couple the electric motor22to the inverter system54in order to output AC power for powering the electric motor22. For example, the inverter system54may receive DC power from a battery pack or some other high voltage power source and may convert the DC power to three-phase AC power. The AC power is carried to the electric motor22by the terminal block assembly58for powering the electric motor22.

The terminal block assembly58may include a plurality of bus bars60for electrically connecting the inverter system54and the electric motor22. In the illustrated embodiment, the inverter system54is configured to provide a three-phase output to the electric motor22, and thus the terminal block assembly58includes a total of three bus bars60. However, the total number of bus bars60is not intended to limit this disclosure, and a greater or fewer number of bus bars than are shown in the figures associated with this disclosure could be employed within the terminal block assembly58.

The current sensor assembly64is configured for detecting current flowing between the inverter system54and the electric motor22in order to more reliably manage and control operation of the electric motor22. The current sensor assembly64may include a plurality of bus bars70. Like the terminal block assembly58, the current sensor assembly64may include a total of three bus bars70. However, the total number of bus bars70is not intended to limit this disclosure.

Motor stator leads62, which are connected to windings of a motor stator of the electric motor22, are connected to first end portions66of the bus bars60of the terminal block assembly58, and second, opposite end portions68of the bus bars60are connected to the bus bars70of the current sensor assembly64. Opposite ends of the bus bars70of the current sensor assembly64may operably connect to power module cards of the inverter system54.

In an embodiment, the bus bars60,70are made of a metallic material, such as copper, for example. However, other metallic materials may also be suitable and are thus also contemplated within the scope of this disclosure.

The bus bars70of the current sensor assembly64may be required to carry high powered currents during some vehicle conditions. The thermal performance of the current sensor assembly64can limit the currently carrying performance of the inverter system54. It is therefore desirable to actively cool the bus bars70of the current sensor assembly64. This disclosure thus describes liquid cooled current sensor assemblies that are capable of actively managing the heat generated by the bus bars70during high power, high current operation of the power system56.

FIGS.3,4,5, and6illustrate an exemplary current sensor assembly64for use within a power system, such as the power system56ofFIG.2. The current sensor assembly64may include a current sensor case72, the bus bars70, and a cooler74.

A plurality of current sensors69(schematically shown inFIG.3) may be housed within the current sensor case72. In an embodiment, one current sensor69is provided for each bus bar70. The current sensors69are configured to monitor a flow of current through the bus bars70. The current sensors69may generate control signals that are provided to a controller of the inverter system54for regulating the power provided to the electric motor22.

The bus bars70may extend through the current sensor case72. First end portions76of the bus bars70may extend outside of the current sensor case72for connection to the bus bars60of the terminal block assembly58, and second end portions78of the bus bars70may extend outside of the current sensor case72for connection to power module cards80of the inverter system54. The power module cards80may be positioned within slots82of a cooler84of the inverter system54(seeFIG.3).

In an embodiment, the first end portions76of the bus bars70extend upwardly relative to a first side86of the current sensor case72, and the second portion portions78extend laterally away from a second side88of the current sensor case72. The second side88may be an opposite side of the current sensor case72from the first side86. The first side86and the second side88are generally longitudinally extending sides of the current sensor case88.

In another embodiment, each bus bar70includes a bend90(best shown inFIG.5) that positions the first end portions76at an angle α relative to mid-sections92of the bus bars70that connect between the first and second end portions76,78. The bend90may be a 90 degree bend, in an embodiment. However, other configurations are also contemplated. The bus bars70may be arranged such that the bends90are positioned outside of the current sensor case72when the bus bars70are positioned therein.

The cooler74may be positioned against a top surface94of the current sensor case72. The cooler74and the current sensor case72may thus share a common interface between the two components.

The cooler74may be integrated together with the current sensor case72. In an embodiment, the current sensor case72and the cooler74are made of the same polymeric material. In such an embodiment, the current sensor case72and the cooler74may be integrated together via an injection molding process or any other suitable manufacturing process.

In another embodiment, the current sensor case72may be constructed of a polymeric material and the cooler74may be constructed of a metallic material. In such an embodiment, the cooler74may be integrated with the current sensor case72via an ultrasonic welding process or any other suitable welding process.

A surface96of the cooler74that extends above the first side86of the current sensor case72may include indentations98for accommodating the first end portions76of the bus bars70. Each indentation98is configured to receive one of the bus bars70. A trim section100of the surface96may extend between adjacent indentations98. By virtue of the indentations98and the trim sections100, the surface96is configured to support the first end portions76of the bus bars70against bending deformation during assembly.

As best illustrated inFIG.6, a cooling circuit104may be provided inside the cooler74. A dividing plate106may be positioned within an interior of the cooler74for establishing two or more interconnected cooling channels108of the cooler74. In an embodiment, the dividing plate106is L-shaped and includes a first end portion110that connects to an interior wall112of the cooler74and a second end portion114that is spaced apart from another interior wall116of the cooler74. A gap118thus extends between the interior wall116and the second end portion114of the dividing plate106to allow fluid to flow from one cooling channel108to another.

An inlet port120of the cooler74is configured to receive and direct a coolant C (e.g., oil, glycol, etc.) into the cooling circuit104. As the coolant C circulates through the cooling channels108, the coolant C picks up and takes away heat from the bus bars70, which are in direct contact with the cooler74at the indentations98and the bottom surface of the cooler74, thereby ensuring high cooling performance during high power, high current operation of the power system56.

In an embodiment, a thermal interface material102may be disposed at the interface between the first end portions76of the bus bars70and the surface96of the cooler74against which the first end portions76are received (see, e.g.,FIG.7). The thermal interface material102may include an epoxy resin, a silicone based material, a thermal grease, etc. and is designed to increase the thermal conductivity between the bus bars70and the surface96that overlies the cooling circuit104.

In an embodiment, the cooling circuit104of the cooler74may receive the coolant C in series with the cooler84of the inverter system54. In such an embodiment, the coolant C exiting an outlet port124(seeFIG.3) of the cooler84may be delivered to the inlet port120of the cooler74. In another embodiment, the cooling circuit104of the cooler74may receive the coolant C in parallel with the cooler84of the inverter system54. In either case, the cooler74of the current sensor assembly64and the cooler84of the inverter system54may be part of a closed thermal loop that is arranged to circulate the coolant C through both the cooler74and the cooler84for actively cooling various components of the power system56.

The coolant C may exit the cooling channels108of the cooling circuit104through an outlet port122of the cooler74. In an embodiment, the outlet port122interfaces with an interior wall126that is opposite from the interior wall116. However, other configurations are also contemplated within the scope of this disclosure.

FIG.8illustrates another exemplary current sensor assembly64-2. The current sensor assembly64-2is similar to the current sensor assembly64described above and illustrated inFIGS.3-7. However, in this embodiment, the current sensor assembly64-2includes a cooler74-2having a cooling circuit104-2that is a slightly modified version of the cooling circuit104of the cooler74of the current sensor assembly64described above.

For example, the cooling circuit104-2of the cooler74-2may include a plurality of dividing plates106-2that are positioned within an interior of the cooler74-2for establishing a multitude of interconnected cooling channels108-2of the cooler74-2. Each of the dividing plates106-2may be a linear plate that excludes any bends. In addition, in this embodiment, an inlet port120-2and an outlet port122-2of the cooling circuit104-2may be disposed at opposite ends of the cooler74-2.

The current sensor assemblies of this disclosure provide efficient and cost effective cooling of bus bars by using direct liquid cooling schemes. The active cooling schemes significantly improve the thermal performance of the bus bars and therefore enhance their current carrying capabilities, thereby improving the overall reliability and durability of the inverter system. Further, the proposed current sensor assembly designs promote a more compact design that is lightweight and cost effective to manufacture.