Power Conversion Apparatus Dual Emergency Stop Monitoring
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Solution Overview
Problem
Existing power conversion systems face reliability issues in emergency stop operations due to complex diagnosis circuits, which can impair the overall apparatus reliability and may not ensure safe stopping.
Innovation Solution
A power conversion system with a dual emergency stop command system, where a supervisory monitoring and control device generates and monitors emergency stop signals, and the control circuit delays the start of operation by a predetermined time to ensure reliable emergency stops, incorporating a monitoring circuit to confirm the emergency stop circuit's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a self-diagnosis circuit is added to confirm the emergency stop circuit is not broken, then the reliability of emergency stop is improved, but the device complexity increases and the overall reliability is impaired
Solution Approach 1:
The emergency stop circuit performs self-confirmation by utilizing the existing dual command signal structure. The control circuit generates delayed operation start signals that automatically confirm the emergency stop circuit's functionality without requiring external diagnosis circuits. The system serves itself by using its own operational signals to verify safety circuit integrity.
Solution Approach 2:
The control circuit serves multiple functions: it generates PWM signals for motor control, generates delayed operation start signals for emergency stop confirmation, and monitors emergency stop circuit functionality. By making the control circuit multi-functional, separate diagnosis circuits become unnecessary, reducing overall system complexity while maintaining reliability.
2Productivity
If the operation starts immediately after receiving the operation command signal, then the productivity is improved, but the reliability of emergency stop is compromised because there is no time to confirm circuit functionality
Solution Approach 1:
The control circuit performs preliminary action by generating delayed operation start signals before the motor actually starts operating. This preliminary signal generation confirms that the emergency stop circuit is functional and ready, ensuring safety is verified in advance while maintaining quick operational response.
Solution Approach 2:
The system dynamically adjusts the timing between receiving the operation command and actual motor operation. The control circuit introduces a controlled delay period during which emergency stop circuit confirmation occurs, then seamlessly transitions to normal operation. This dynamic timing management ensures both safety verification and operational efficiency.
Data Source
AI summary
A power conversion apparatus and a power conversion system that ensure safety capable of reliably performing an emergency stop and have a failure monitoring function are provided. The command signal for emergency stop of the power conversion apparatus between the supervisory monitoring and control device and the power conversion apparatus is to be a dual system, and the supervisory monitoring and control device monitors a performance of emergency stop of the power conversion apparatus by delaying the start of operation for a predetermined time from the operation command signal output. The supervisory monitoring and control device check a soundness of the power conversion apparatus by generating a test operation signal during that delay period.