Electric Drive Apparatus Fixed Ratio Control
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Solution Overview
Problem
Existing electric drive apparatus with continuously-variable transmissions face efficiency and compactness issues due to lower efficiency compared to constant-mesh speed reduction mechanisms, especially when ratio coverage is wide, leading to increased motor and inverter size, which complicates mountability.
Innovation Solution
An electric drive apparatus with a controller that switches between a first control mode to maintain a fixed transmission ratio and a second control mode to vary the ratio, optimizing motor and transmission operation within predetermined ranges to achieve desired torque and efficiency, while minimizing the size of the motor and inverter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the ratio coverage of the continuously-variable transmission is increased to expand the variation width of the gear ratio, then the adaptability is improved, but the transmission efficiency deteriorates
Solution Approach 1:
The control device dynamically adjusts the transmission ratio based on operating conditions by switching between fixed ratio control mode and ratio variation control mode. The system determines whether to maintain a fixed transmission ratio or allow variation based on real-time operating parameters, optimizing the balance between adaptability and efficiency
Solution Approach 2:
The control device changes the transmission ratio parameter dynamically based on operating conditions. By switching between fixed ratio control (where the ratio is held constant) and ratio variation control (where the ratio changes with operating conditions), the system optimizes both adaptability and transmission efficiency
2Loss of energy
If the ratio coverage is decreased to improve transmission efficiency, then the energy loss is reduced, but the motor size increases
Solution Approach 1:
The control device dynamically adjusts the transmission ratio based on operating conditions by switching between fixed ratio control mode and ratio variation control mode. The system determines whether to maintain a fixed transmission ratio or allow variation based on real-time operating parameters, optimizing the balance between efficiency and motor size
Solution Approach 2:
The control device changes the transmission ratio parameter dynamically based on operating conditions. By switching between fixed ratio control (where the ratio is held constant) and ratio variation control (where the ratio changes with operating conditions), the system optimizes both efficiency and motor size
3Use of energy by moving object
If the continuously-variable transmission is used to achieve optimal motor efficiency, then the energy utilization is improved, but the device complexity increases
Solution Approach 1:
The control device dynamically adjusts the transmission ratio based on operating conditions by switching between fixed ratio control mode and ratio variation control mode. The system determines whether to maintain a fixed transmission ratio or allow variation based on real-time operating parameters, optimizing the balance between motor efficiency and system complexity
Solution Approach 2:
The control device changes the transmission ratio parameter dynamically based on operating conditions. By switching between fixed ratio control (where the ratio is held constant) and ratio variation control (where the ratio changes with operating conditions), the system optimizes both motor efficiency and transmission system complexity
Data Source
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AI summary
An electric drive apparatus includes a controller for controlling an electric motor and a continuously-variable transmission connected with the motor. The controller controls the motor and the continuously-variable transmission in a first control mode to control the transmission ratio of the continuously-variable transmission to a predetermined fixed ratio so as to hold the transmission ratio at the fixed ratio, and to control the motor to achieve the demand motor torque when a demand motor operation point determined from a predetermined assumed ratio is within a predetermined operation range, and to control the motor and the continuously-variable transmission in a second control mode to vary the transmission ratio and to control the motor to achieve a desired driving torque for a driven member driven by the motor when the demand motor operation point is not within the predetermined operation range.