Electric Motor Auxiliary Power Generation via Speed Modifier
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Solution Overview
Problem
Existing propulsion systems with electric motors face challenges in efficiently generating auxiliary power while maintaining torque accuracy and managing power losses, particularly in hybrid vehicles that switch between electric and internal combustion engine modes.
Innovation Solution
A controller-based system that adjusts rotor speed and stator current commands using a delta factor, derived from a closed-loop control module, to generate auxiliary power by modifying the electric motor's operation, directing this power through a cooling loop to the inverter and DC power source, thereby optimizing energy use and maintaining torque linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the electric motor operates at standard efficiency points, then energy efficiency is improved, but auxiliary power generation capability deteriorates
Solution Approach 1:
The system dynamically adjusts the motor operating point by modifying rotor speed and stator current commands based on real-time conditions. The controller varies the operating parameters to shift between efficiency optimization and auxiliary power generation modes, allowing the motor to adapt its characteristics dynamically rather than being fixed at a single operating point.
Solution Approach 2:
The invention changes the operational parameters of the motor by introducing a speed modifier that adjusts the rotor speed command and modifies stator current commands. These parameter changes enable the motor to operate in a region that generates increased losses (auxiliary power) while maintaining torque accuracy, effectively transforming the motor from a purely drive component to a dual-function component.
2Power
If the motor operates to generate auxiliary power through modified speed and current commands, then auxiliary power generation is improved, but torque accuracy deteriorates
Solution Approach 1:
The system employs feedback control by continuously monitoring the actual torque output and comparing it with the requested torque. The controller adjusts the modified stator current commands based on this feedback to maintain torque accuracy despite the speed and current modifications intended for auxiliary power generation. This closed-loop control ensures that torque requirements are met while still generating the desired auxiliary power.
Solution Approach 2:
The controller dynamically adjusts the operating parameters (rotor speed and stator current) in real-time to balance auxiliary power generation with torque accuracy. By continuously modifying these parameters based on system conditions and torque feedback, the system maintains precise torque control while operating in the auxiliary power generation mode.
3Adaptability or versatility
If the motor operates below base speed for enhanced performance, then adaptability is improved, but power loss management becomes more complex
Solution Approach 1:
The control strategy is segmented into different operational regions and modes. The controller divides the operating range into base speed and below base speed regions, and further segments the control functions into torque control, speed modification, and auxiliary power management. This segmentation allows each segment to be optimized independently while maintaining overall system adaptability.
Solution Approach 2:
The system uses dynamic control adjustments to manage the complexity of operating below base speed. The controller continuously adapts the speed modifier and current commands based on the operating region, allowing the system to maintain simplicity in each specific mode while achieving overall versatility across the entire operating range.
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
The system effectively generates auxiliary power, increasing losses for heating or regenerative braking, while ensuring torque accuracy and efficiency in electric motor operation, even below base speed, thus enhancing the performance of hybrid vehicles.
Implementation Method 1
The electric motor includes a rotor with at least one permanent magnet and a stator. A controller is configured to receive a torque request and selectively command the electric motor based in part on the torque request.
Implementation Method 2
The system effectively generates auxiliary power, increasing losses for heating or regenerative braking
Implementation Method 3
A cooling loop may be positioned to be in thermal communication with the electric motor, the inverter and/or the direct current power source
Implementation Method 4
The controller may be configured to at least partially direct the auxiliary power, through the cooling loop, to the inverter and/or the direct current power source
Data Source
AI summary
A propulsion system having an electric motor and corresponding method. A controller is configured to receive a torque request and selectively command the electric motor. The controller has a processor and tangible, non-transitory memory on which instructions are recorded for a method of generating an auxiliary power. The controller is configured to obtain a desired auxiliary power and a delta factor (δ). The delta factor is set as a speed modifier (Δω=δ) when the cosine of an angle (θ), between a constant torque unit vector and a decreasing voltage ellipse unit vector, is less than a predefined threshold. A modified rotor speed is obtained as a sum of an original rotor speed and a speed modifier (Δω). The controller is configured to obtain modified stator current commands based on the modified rotor speed and torque request. The auxiliary power is generated by commanding the modified stator current commands.