Rotary Electric Machine Control System with Dynamic Threshold Adjustment
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Solution Overview
Problem
Existing rotary electric machine control systems face issues with excessive current flow when rapidly switching control modes, particularly during sudden changes in the number of revolutions, leading to potential equipment breakdowns due to excessive voltage applied to the machine.
Innovation Solution
A rotary electric machine control system that includes a measurement device to track the number of revolutions and a threshold changing unit to adjust control switching thresholds, such as phases or modulation degrees, to facilitate rapid mode switching, thereby reducing voltage and preventing overcurrent flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the switching line is set on the smaller angle side of the maximum efficiency characteristic line to avoid chattering, then control stability is improved, but the switching from rectangular-wave control mode to over-modulation control mode becomes slow when the number of revolutions rapidly drops
Solution Approach 1:
The patent applies dynamics by making the switching line angle variable rather than fixed. The control switching phase is dynamically adjusted based on the rate of change of the number of revolutions. When the number of revolutions rapidly decreases, the switching line angle is increased (moved toward the larger angle side) to enable faster switching from rectangular-wave control to over-modulation control, preventing excessive voltage application. This dynamic adjustment resolves the contradiction between maintaining control stability and achieving fast switching response.
2Stability of the object's composition
If the control mode switching is delayed to maintain stable operation, then control stability is improved, but excessive voltage is applied to the rotary electric machine causing potential equipment breakdown
Solution Approach 1:
The patent applies preliminary action by detecting the rate of change of the number of revolutions in advance and proactively adjusting the control switching phase before excessive voltage damage can occur. When a rapid decrease in revolutions is detected, the system preemptively shifts the switching line to enable faster mode transition, preventing the harmful effect of excessive voltage application to the stator coils and protecting equipment reliability.
3Speed
If the switching line is set on the larger angle side to enable faster switching, then switching speed is improved, but chattering in control occurs during mode switching
Solution Approach 1:
The patent resolves this contradiction through dynamic adjustment of the switching line angle based on operating conditions. The control switching phase is adapted in real-time: it is increased (moved toward larger angle) only when rapid switching is needed due to sudden revolution drop, and maintained at the smaller angle side during normal operation to prevent chattering. This conditional dynamic adjustment allows the system to achieve fast switching when necessary while maintaining stability during routine operation.
Data Source
AI summary
A rotary electric machine control system includes a rotary electric machine (second motor generator), a number-of-revolutions sensor that measures the number of revolutions per predetermined time period of the rotary electric machine, and a controller. The controller has a threshold changing unit for changing a control switching phase that is a control switching threshold to be used for switching the control mode of the rotary electric machine, according to a measurement result of the number of revolutions.