Rotary Electric Machine Control System Torque Limitation
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Solution Overview
Problem
Existing rotary electric machine control systems face challenges in preventing over-currents, which can damage batteries and circuits, particularly in hybrid systems where torque limitations are not effectively managed, leading to inefficient energy use and reduced battery life.
Innovation Solution
A rotary electric machine control system that includes battery electric power calculation means, torque limitation means, and battery electric power abrupt variation estimation means to dynamically adjust torque limitations based on the state of battery electric power variation, ensuring appropriate torque limitation during both non-abrupt and abrupt variation times to prevent over-currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If torque limitation is performed based on amount of increase in consumed power, then over-current protection is improved, but torque limitation is applied even when torque itself is small causing loss of drive force
Solution Approach 1:
The patent changes the control parameter from 'amount of increase in consumed power' to 'absolute value of consumed power' for torque limitation decisions. This allows the system to apply torque limitation based on the actual power level rather than the rate of change, preventing unnecessary limitation when torque is small but power increase is large, while still protecting against over-current when absolute power is high.
2Productivity
If torque limitation is not performed when absolute consumed power is large but variation is small, then drive force is maintained, but battery or circuit may be damaged by over-current
Solution Approach 1:
The patent fundamentally changes the control parameter from monitoring power variation rate to monitoring absolute power level. By using absolute consumed power values, the system can identify when high power demand exists regardless of whether it is increasing or decreasing, enabling appropriate torque limitation to protect the battery and circuit while maintaining drive force when safe operating levels are reached.
3Speed
If motor rotational speed increases abruptly due to load torque decrease, then motor response is improved, but large current passes through battery causing over-current and reduced battery life
Solution Approach 1:
The patent applies preliminary torque limitation based on absolute power levels before abrupt speed increases can cause dangerous current spikes. By continuously monitoring absolute consumed power and preemptively limiting torque when power approaches dangerous levels, the system prevents the chain reaction of abrupt speed increase leading to over-current, thereby protecting battery life while allowing normal rapid response when power levels are safe.
Data Source
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AI summary
To provide a rotary electric machine control system for a hybrid system including a pair of rotary electric machines that are supplied with electric power from a common battery to respectively serve as a generator and a motor, in which components from the battery to an inverter are reliably protected by preventing an over-current. A rotary electric machine control system includes torque limitation means for limiting an output torque of a rotary electric machine, and battery electric power abrupt variation estimation means for estimating that battery electric power is in an abrupt variation state in which the battery electric power is varying abruptly on the basis of at least one of a variation rate of the battery electric power and a variation rate of a rotational speed of the rotary electric machine. The torque limitation means changes, in the case where the battery electric power abrupt variation estimation means estimates that the battery electric power is in the abrupt variation state, a mode of limitation of the output torque from a mode of limitation of the output torque used in a non-abrupt variation state in which the battery electric power is not varying abruptly.