Torque Control at Zero Speed Using Effective Speed Parameter
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Power domain-based control systems for torque-generating systems, such as hybrid electric powertrains, face challenges when operating at or near zero speed, as they ineffectively differentiate across various torque request levels due to the breakdown in power calculations, which results in suboptimal performance.
Innovation Solution
A controller is programmed to determine an effective speed as a calibrated non-zero value based on the torque request level when actual speed is zero, allowing the system to calculate effective power and execute control actions to select appropriate operating modes, thereby improving power-based control logic at zero speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If power domain-based control is used to provide two control degrees of freedom (torque and speed), then control flexibility and system performance are improved, but the control system breaks down at zero speed where power calculations become ineffective
Solution Approach 1:
The patent changes the parameter used for control calculations from actual speed to effective speed. When actual speed is zero or near-zero, the controller substitutes a calibrated non-zero effective speed value, allowing power domain-based control to continue functioning reliably. This parameter substitution resolves the breakdown issue while maintaining the two-degree-of-freedom control flexibility.
2Device complexity
If actual speed is used directly in power calculations at zero speed, then calculation simplicity is maintained, but the system cannot differentiate across various torque request levels
Solution Approach 1:
The patent introduces effective speed as an intermediary parameter between actual speed and power calculations. This intermediary allows the system to maintain simple power-based control logic while achieving accurate torque request differentiation. The effective speed acts as a mediator that preserves the benefits of power domain control without suffering from its limitations at zero speed.
3Measurement precision
If multiple control domains are used to maintain control accuracy at zero speed, then torque request differentiation is improved, but system complexity increases
Solution Approach 1:
The patent makes the effective speed parameter universal, allowing a single power domain-based control system to handle both zero-speed and non-zero-speed operations accurately. This multi-functional approach eliminates the need for separate control domains or switching logic, maintaining torque request differentiation capability while reducing overall system complexity.
Data Source
AI summary
A torque-generating system includes one or more torque-generating devices, a transmission having an output member, and a controller. The controller executes a method to control an operation of the system when the output member is operating at zero output speed. The controller is programmed to determine a torque request level and an actual speed of the output member, and an effective speed of the output member, as a calibrated non-zero value, using the torque request level when the determined actual speed is zero. The controller calculates an effective power of the powertrain using the effective speed and torque request level. A control action is executed with respect to the powertrain using the calculated effective power, including transmitting powertrain control signals to the torque-generating device(s) to select an appropriate powertrain operating mode.