System and method for thermal and lubrication management in electric drive module
A thermal management system for an electric drive module configured to generate and transfer drive torque to a driveline for propulsion of an electric vehicle is provided. The system includes a motor housing, a pump, a first and second temperature sensor and a controller. The motor housing has an electric motor and a sump. The pump delivers fluid through a hydraulic circuit to the electric motor. The first temperature sensor senses a first temperature at the pump. The second temperature sensor senses a second temperature at the sump. The controller is configured to: determine an initial pump flow based on a heat losses associated with a speed and torque of the motor; command the pump to operate at an initial speed to satisfy the initial pump flow; compare at least one of the first and second temperatures to a threshold; command the pump to operate at a first modified speed.
1 . A thermal management system for an electric drive module (EDM) configured to generate and transfer drive torque to a driveline for propulsion of an electric vehicle, the thermal management system comprising:
a motor housing having an electric motor and a sump;
a pump that delivers fluid through a hydraulic circuit to the electric motor;
a first temperature sensor that senses a first temperature at the pump;
a second temperature sensor that senses a second temperature at the sump;
a poppet valve disposed in the fluid circuit and selectively communicating fluid from the fluid circuit to at least one shower head on the motor housing;
a controller configured to:
determine an initial pump flow based on a heat losses associated with a speed and torque of the electric motor;
command the pump to operate at an initial speed to satisfy the initial pump flow;
compare at least one of the first and second temperatures to a threshold;
command the pump to operate at a first modified speed, distinct from the initial speed based on the comparing;
determine whether a power loss of the system exceeds a power loss threshold; and
operate the pump at a second modified speed, higher than the initial speed, wherein the second modified speed increases a pressure in the hydraulic circuit thereby opening the poppet valve.
2 . The thermal management system of claim 1 , wherein commanding the pump to operate at a modified speed further comprises:
determining whether at least one of the first and second temperatures is less than a threshold and reducing the speed of the pump based on a determination that at least one of the first and second temperatures is less than the threshold.
3 . The thermal management system of claim 2 , wherein commanding the pump to operate at a modified speed further comprises:
determining whether at least one of the first and second temperatures is greater than a threshold and increasing the speed of the pump based on a determination that at least one of the first and second temperatures is greater than the threshold.
4 . The thermal management system of claim 1 , wherein the controller is configured to determine the initial pump flow based on (i) a gearbox heat loss lookup table based on the speed and torque of the electric motor; and (ii) a motor heat loss lookup table based on the speed and torque of the electric motor.
5 . The thermal management system of claim 1 , wherein the fluid comprises oil.
6 . A method of operating a thermal management system for an electric drive module (EDM) configured to generate and transfer drive torque to a driveline for propulsion of an electric vehicle, the EDM having a motor housing having an electric motor and a sump; a pump that delivers fluid through a hydraulic circuit to the electric motor; a first temperature sensor that senses a first temperature at the pump; a second temperature sensor that senses a second temperature at the sump; and a poppet valve disposed in the fluid circuit, the method comprising;
determining, at a controller, an initial pump flow based on a heat losses associated with a speed and torque of the electric motor;
commanding, at the controller, the pump to operate at an initial speed to satisfy the initial pump flow;
comparing, at the controller, at least one of the first and second temperatures to a threshold;
commanding, at the controller, the pump to operate at a first modified speed, distinct from the initial speed based on the comparing;
selectively communicating fluid from the fluid circuit to at least one shower head on the motor housing using the poppet valve;
determining whether a power loss of the system exceeds a power loss threshold; and
operating the pump at a second modified speed, higher than the initial speed, wherein the second modified speed increases a pressure in the hydraulic circuit thereby opening the poppet valve.
7 . The method of claim 6 , wherein commanding the pump to operate at a modified speed further comprises:
determining whether at least one of the first and second temperatures is less than a threshold; and
reducing the speed of the pump based on a determination that at least one of the first and second temperatures is less than the threshold.
8 . The method of claim 7 , wherein commanding the pump to operate at a modified speed further comprises:
determining whether at least one of the first and second temperatures is greater than a threshold; and
increasing the speed of the pump based on a determination that at least one of the first and second temperatures is greater than the threshold.
9 . The method of claim 6 , further comprising:
determining the initial pump flow based on (i) a gearbox heat loss lookup table based on the speed and torque of the electric motor; and (ii) a motor heat loss lookup table based on the speed and torque of the electric motor.