Electric Motor Control Device Torque Discontinuity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing motor control systems experience torque discontinuity and increased computation load when switching between control modes, leading to discomfort for drivers and higher costs due to the need for more powerful computation devices.
Innovation Solution
The system switches between current control and voltage phase control modes based on motor state, using a motor constant generator to calculate d-q axis voltage command values and torque estimation, reducing computation load by eliminating torque feedback in the current control mode and using precomputed tables for mode-specific parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If torque feedback loop is added to current control mode to maintain steady-state torque, then torque discontinuity is suppressed, but computation load increases
Solution Approach 1:
The patent pre-calculates and stores torque values in a lookup table during system initialization or operation. When control mode switching is detected, the system retrieves pre-computed torque values from the table to maintain torque continuity, avoiding the need for real-time torque feedback computation in current control mode.
Solution Approach 2:
The patent creates a simplified model of torque behavior by storing torque characteristics in a lookup table. Instead of computing torque in real-time through complex feedback loops, the system copies pre-computed torque values from the table, reducing computational requirements while maintaining torque continuity across control mode transitions.
2Device complexity
If computation period is extended to reduce computation load, then control performance decreases
Solution Approach 1:
The system performs torque computation in advance and stores results in a lookup table. During operation, especially during control mode switching, the system retrieves pre-computed values instantaneously, maintaining fast response times without requiring extended computation periods.
Solution Approach 2:
The lookup table serves as a self-service mechanism that provides torque values without requiring active computation during critical operations. The system feeds itself pre-computed data, eliminating the trade-off between computation time and control performance.
3Reliability
If high performance computation device is employed to handle torque feedback computation, then torque continuity is maintained, but cost increases
Solution Approach 1:
The patent replaces complex real-time torque computation with a lookup table containing pre-computed torque values. This approach uses simple memory retrieval instead of expensive high-performance computation hardware, maintaining torque continuity while reducing device cost.
Solution Approach 2:
The patent uses a simple lookup table structure that requires minimal computational resources compared to high-performance computation devices. The table can be easily stored in standard memory, replacing the need for expensive computation hardware while achieving the same torque continuity goal.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An electric motor control device includes: a motor constant generator configured to generate a motor constant by using a temperature as a parameter; a current control unit configured to generate a current command value to an electric motor based on the motor constant and a torque command value and execute a current control mode in which a voltage applied to the electric motor is controlled to match the current command value; a voltage phase control unit configured to calculate a torque estimation value of the electric motor and execute a voltage phase control mode in which a feedback operation is performed for a voltage phase based on the difference between the torque estimation value and the torque command value; and a control mode switching unit configured to switch to the voltage phase control mode in a high rotation area where a flux weakening control is performed. The torque estimation value is calculated using the motor constant common to generation of the current command value in the current control mode.