EV Motor Resistive Fluid Preheating via DC Alignment
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Solution Overview
Problem
In electric vehicles, engine fluids cool below the desirable operating temperature during prolonged inactivity, especially in cold environments, leading to increased viscosity and resistance, which requires additional energy to overcome, thereby reducing the vehicle's range and causing passenger discomfort due to delayed cabin heating.
Innovation Solution
The system includes a powertrain with a battery, a three-phase electric motor, and a power controller that determines DC currents to resistively heat the engine fluid by aligning the electromagnetic field of the stator with the rotor's magnetic field, circulating the fluid using a pump, and monitoring temperature and battery state of charge to optimize heating without inducing torque, ensuring efficient pre-warming before vehicle operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If DC current is applied to the electric motor to heat the fluid, then the fluid temperature increases, but the battery state of charge decreases
Solution Approach 1:
The system performs preliminary heating of the engine fluid by applying DC current to the electric motor before the vehicle is driven. This advance action ensures the fluid is at optimal temperature when needed, avoiding the need for heating during actual operation and preserving battery charge for propulsion.
Solution Approach 2:
The electric motor serves dual purposes: it propels the vehicle during normal operation and acts as a heating element for the engine fluid when DC current is applied. This self-service capability eliminates the need for a separate heating system, using the motor's own resistance to generate heat.
2Temperature
If DC current is applied to the electric motor to heat the fluid, then the fluid temperature increases, but the vehicle range decreases
Solution Approach 1:
The system performs preliminary heating of the engine fluid by applying DC current to the electric motor before the vehicle is driven. This advance action ensures the fluid is at optimal temperature when needed, avoiding the need for heating during actual operation and preserving battery charge for propulsion, thereby maintaining vehicle range.
3Loss of energy
If the electric motor is used for heating, then the fluid heating efficiency improves, but the motor may induce unwanted torque
Solution Approach 1:
The system extracts only the heating function from the electric motor by applying DC current to the windings, while deliberately preventing the motor from generating mechanical torque. This separation allows the motor to serve as an efficient heater without producing unwanted rotational force.
Solution Approach 2:
The system changes the electrical parameter from three-phase AC current (which produces rotating magnetic field and torque) to DC current (which produces stationary magnetic field and heat without torque). This parameter change transforms the motor's function from mechanical propulsion to thermal heating.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively pre-warms the engine fluid to optimal temperatures before vehicle use, reducing energy consumption and improving range while ensuring passenger comfort by maintaining efficient engine operation and cabin heating without depleting the battery.
Implementation Method 1
determining a DC current for each of the three motor phases such that the electromagnetic field of the stator mirrors the magnetic field orientation of the rotor; and by providing the determined DC currents to the electric motor to resistively heat the fluid
Implementation Method 2
determining a DC current for each of the three motor phases such that the electromagnetic field of the stator mirrors the magnetic field orientation of the rotor
Implementation Method 3
a fluid circuit in communication with the electric motor, along with a fluid pump to circulate the engine fluid within the fluid circuit
Data Source
AI summary
An electric vehicle powertrain includes a battery configured to couple with an external power source, a power plant including at least one three-phase electric motor, and a power controller configured to receive electrical energy from the battery and to controllably provide electrical energy to the at least one electric motor. The electric motor includes a stator having a plurality of electrical windings and a rotor having a magnetic field orientation, with the rotor being configured to rotate relative to the stator. The power controller is configured to warm an engine fluid by determining the position of the rotor relative to the stator; determining a DC current for each of the three motor phases such that the electromagnetic field of the stator mirrors the magnetic field orientation of the rotor; and by providing the determined DC currents to the electric motor to resistively heat the fluid.