Inverter Control for Multiphase Motor Short Circuit Protection
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Solution Overview
Problem
Conventional control systems for multiphase rotary electric machines fail to effectively manage short circuits in inverters, leading to torque fluctuations, increased heating, and vibration in hybrid vehicle systems, particularly when the internal combustion engine is stopped, as they do not adequately control the output torque and rotation of the rotary shaft.
Innovation Solution
A control system that includes a determining component to identify inverter malfunctions and a limiting component to manage the rotation state of the internal combustion engine's rotary shaft through the torque-splitting mechanism, using the electrical conditions of the multiphase rotary electric machine to prevent vibration and maintain current continuity, and by switching the inverter's switching elements to control torque and prevent excessive current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a breaker circuit is provided to shut down current flow in case of short circuit, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent replaces the mechanical breaker circuit with an electronic control system that uses switching elements to open circuit phases electronically. The control unit detects short circuits and activates switching elements to disconnect affected phases, eliminating the need for physical breaker circuits while maintaining protection functionality.
Solution Approach 2:
The patent changes the operational parameters of switching elements to achieve protection. By controlling the on/off states of switching elements based on detected short circuit conditions, the system dynamically adjusts circuit connectivity without requiring additional protective hardware components.
2Productivity
If switching elements are operated to control output torque, then productivity is improved, but object-generated harmful factors increase due to torque fluctuations and heating
Solution Approach 1:
The patent implements a feedback mechanism where the control unit continuously monitors the states of switching elements and detects short circuit conditions. Based on this feedback, the control unit adjusts the operation of switching elements to maintain stable torque output and prevent harmful effects. The system detects abnormal current patterns and responds by modifying switching sequences to eliminate torque fluctuations and reduce heating.
Solution Approach 2:
The patent applies partial action by selectively controlling only the necessary switching elements rather than all phases simultaneously. When a short circuit is detected in one phase, the control unit activates switching elements to open only the affected phase while maintaining operation of healthy phases, thereby controlling torque output with minimal disruption and reduced harmful effects.
3Ease of operation
If the inverter controls the multiphase rotary electric machine, then ease of operation is improved, but object-affected harmful factors increase due to vibration in the power transmission system
Solution Approach 1:
The patent replaces mechanical vibration damping mechanisms with electronic control of switching elements. The control unit detects vibration-inducing conditions and adjusts switching sequences to eliminate resonant frequencies and smooth torque delivery, thereby reducing system vibration without requiring additional mechanical dampers or vibration control components.
Data Source
AI summary
A control system for multiphase rotary electric machines is provided. The control system carries out control of the output of a multiphase rotary electric machine by operating switching elements of an inverter, so that more appropriate measure can be taken when malfunction has occurred in the inverter. A rotary shaft of an internal combustion engine, a rotary shaft of a generator and a rotary shaft of a motor are linked through a torque-splitting mechanism. The control system carries out failsafe processes, at the occurrence of short circuit in a switching element of the inverter, to control load torque of the generator so as to prevent rotation of a rotary shaft of the internal combustion engine in a non-operative state, which rotation is induced by a motive force of the motor.