Regenerative Current Limiting for DC Motor Torque Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing DC machine systems, particularly in electric power steering, face challenges in managing regenerative current to protect the voltage source without compromising torque capability, as they require limiting regenerative current to prevent excessive current draw from the battery.
Innovation Solution
A control system with a current command module and a regenerative current limiting module that computes and applies motor current limits based on regenerative current limits, ensuring the motor current command does not exceed specified limits, thereby protecting the voltage source and managing power flow effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If regenerative current is limited to protect the voltage source, then the voltage source is protected from excessive current draw, but the torque capability of the motor is reduced
Solution Approach 1:
The system dynamically adjusts the regenerative current limit based on real-time operating conditions such as motor speed, torque demand, and battery state. The control module continuously modifies the current limit parameter to optimize both protection and performance, transitioning from static to adaptive current limiting that responds to changing system states.
Solution Approach 2:
The invention changes the regenerative current limit parameter dynamically based on motor operating conditions. By adjusting this key parameter according to speed-torque characteristics and system demands, the system achieves optimal balance between protecting the voltage source and maintaining adequate torque capability across different operating regimes.
2Reliability
If the motor current command is modified to ensure current limits are not exceeded, then the voltage source is protected, but the system loses torque capability
Solution Approach 1:
The control module implements feedback by continuously monitoring motor current, speed, and torque demand, then adjusting the regenerative current limit accordingly. This closed-loop approach ensures current limits are respected while minimizing impact on torque capability, as the system learns from and responds to actual operating conditions in real-time.
Solution Approach 2:
The system performs preliminary calculation of the regenerative current limit based on anticipated operating conditions and motor characteristics. By pre-computing appropriate current limits before torque demands arise, the system prepares optimal protection parameters that prevent excessive current draw while preserving torque capability when needed.
Data Source
AI summary
Technical solutions are described for a control system that includes a current command module configured to receive a torque command and output a current command for controlling a direct current (DC) motor, and a regenerative current limiting module configured to receive a regenerative current limit as an input and actively compute a motor current limit based on the regenerative current limit, the regenerative current limiting module configured to limit the current command based on the motor current limit.