Motor Torque Management via Periodic Waveform Modulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electric vehicles face challenges in managing motor torque at low to zero speeds, leading to overheating and reduced operational life due to continuous current application in motor coil phases, which limits torque capabilities near stall conditions.
Innovation Solution
A method and system for managing motor torque in electric vehicles by determining a stall metric, torque limit, and desired torque value, and modifying baseline torque commands to prevent overheating, using a combination of baseline and modulated torque commands, including waveforms like square, pulse-modulated, and sinusoidal waves, to distribute torque effectively across motor phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If continuous current is applied in motor coil phases to maintain torque at low speeds, then torque capability is maintained, but motor overheating occurs and operational life is reduced
Solution Approach 1:
The patent applies periodic action by modulating the torque command signal with waveforms (square, sinusoidal, triangular, sawtooth, pulse-modulated, or piecewise functional waves) superimposed on the baseline torque command. This creates periodic variations in current application to motor phases, allowing torque to be maintained on average while preventing continuous overheating through cyclical current distribution across phases.
Solution Approach 2:
The patent changes the parameter of torque command by adding waveform modulations with varying amplitudes, frequencies, and shapes. The modulation amplitude, frequency, and waveform type are adjusted based on operating conditions (speed, torque demand, temperature) to optimize the balance between maintaining torque capability and preventing motor overheating.
2Temperature
If torque limit is reduced to prevent overheating at low speeds, then motor temperature is controlled, but torque capability near stall conditions is limited
Solution Approach 1:
By using periodic waveform modulations on the torque command, the system achieves effective torque delivery without requiring continuous operation at the torque limit. The periodic nature allows the motor to operate below the continuous torque limit while still providing peak torque capability when needed, thus preventing overheating while maintaining torque capability.
Solution Approach 2:
The patent maintains continuous useful action by ensuring that the time-averaged value of the modulated torque command equals the desired torque value. This continuity is achieved through carefully designed waveforms whose average over a period matches the required torque, allowing the motor to operate continuously without interruption while preventing thermal buildup.
3Force
If baseline torque command is modified with waveforms to distribute torque across phases, then torque capability at low speeds is enhanced, but control system complexity increases
Solution Approach 1:
The control system implements periodic waveform modulations that can be generated using standard signal generation techniques. The complexity is managed by selecting from a有限的 set of waveform types (square, sinusoidal, triangular, sawtooth, pulse-modulated, piecewise functional) and adjusting their parameters (amplitude, frequency, phase) based on operating conditions, rather than requiring complex real-time optimization algorithms.
Solution Approach 2:
The system manages complexity by changing parameters (waveform type, amplitude, frequency) of the modulation signal based on pre-defined operating conditions and lookup tables or simplified algorithms, rather than requiring complex real-time computation. This allows adaptive torque distribution while maintaining relatively simple control logic.
Data Source
AI summary
A system for managing motor torque in a vehicle determines a stall metric corresponding to motor speed and determines a torque limit based on the stall metric. The system determines a desired torque value, and determines whether to generate a modification to one or more baseline torque commands based on the desired torque value and the torque limit. If the baseline torque command is not to be modified, the system generates the one or more baseline torque commands corresponding to one or more motors. If the baseline torque is to be modified, the system generates one or more modified torque commands corresponding to the one or more motors based on the modification and on the one or more baseline torque commands. The modified torque command may include a minimum value that is less than the torque limit and a maximum value that corresponds to a wheel slip torque.