Dual-Coil Motor Torque Control for Ripple-Free Power Balancing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Motor control systems with two coil groups face challenges in maintaining balanced maximum torque generation, leading to torque ripple and discomfort due to unbalanced power feeding, especially when one coil group is overheated or power-limited.
Innovation Solution
A motor control device and method that calculate individual torque command values for each coil group, considering response characteristics, and adjust power feeding using differential torque calculations to maintain balanced torque generation, even when maximum torque is unbalanced.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power feeding to one coil group is restricted to protect from overheating, then reliability of the coil group is improved, but torque balance between coil groups deteriorates causing torque ripple
Solution Approach 1:
The control device calculates differential torque based on the difference between theoretical output torque (from torque command values) and predictive output torque (actual generated torque considering response characteristics). This feedback mechanism detects torque imbalance caused by power restriction and automatically corrects it by adjusting power distribution between coil groups, maintaining torque balance while protecting the overheated coil group
Solution Approach 2:
The system dynamically changes power feeding parameters between coil groups based on real-time torque balance requirements. When one coil group is restricted due to overheating, the control device adjusts the torque command values and power distribution ratios to compensate for the restricted coil group, ensuring total torque remains balanced without compromising the protected coil group's reliability
2Power
If maximum torque of coil groups is unbalanced, then individual coil group performance is optimized, but total motor torque consistency deteriorates
Solution Approach 1:
The control device implements dynamic torque distribution that continuously adapts to changing torque capabilities of individual coil groups. By calculating theoretical output torque from torque command values and predictive output torque from actual performance with response characteristics, the system dynamically adjusts power feeding ratios to maintain consistent total motor torque even when individual coil group maximum torques are unbalanced
Solution Approach 2:
The system changes power feeding parameters in real-time based on the unbalanced torque capabilities of coil groups. The control device adjusts torque command values and power distribution to compensate for differences in individual coil group performance, ensuring that the total motor torque remains consistent across different operating conditions
3Reliability
If assist torque ratio changes before and after torque upper limit is reached, then coil group protection is achieved, but steering comfort deteriorates due to torque fluctuation
Solution Approach 1:
The control device uses feedback from differential torque calculations to detect changes in assist torque ratio that would cause torque fluctuation. When a coil group approaches its torque upper limit, the system automatically adjusts power distribution and torque command values to maintain smooth torque transition, preventing the fluctuation that would otherwise occur and thereby maintaining steering comfort while still protecting the coil group
Solution Approach 2:
The system prepares compensatory torque distribution in advance before a coil group reaches its torque upper limit. By calculating theoretical and predictive output torques continuously, the control device anticipates the upcoming torque limitation and adjusts power feeding ratios proactively, cushioning against the torque fluctuation that would otherwise occur at the transition point and maintaining steering comfort
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An ECU (40) controls a motor (31) including a first coil group (52) and a second coil group (53). The ECU calculates a first torque command value and a second torque command value. The ECU uses a first differential torque, which is the difference between a first theoretical output torque and a first predictive output torque, to correct the second torque command value for the second coil group (53). The ECU uses a second differential torque, which is the difference between a second theoretical output torque and a second predictive output torque, to correct the first torque command value for the first coil group (52). The ECU uses a corrected first torque command value to control power feeding to the first coil group and uses a corrected second torque command value to control power feeding to the second coil group.