Drive Safety Interface Board Architecture for Scalable STO and SBC Control
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Solution Overview
Problem
Existing elevator systems face challenges in implementing a scalable and cost-effective solution for Safe Torque Off (STO) and Safe Brake Control (SBC) operations that meet SIL3 certification requirements across various drive portfolios, necessitating a solution that minimizes integration burden and certification costs.
Innovation Solution
A scalable architecture is introduced, integrating STO and SBC functions on a single board with a drive safety interface board (DSIB) that includes separate circuitry for motor control and brake operation, utilizing a digital isolator to block high-side PWM signals and switches to manage torque and brake power, and monitoring circuitry for safety, allowing for seamless integration with existing motor drives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate control systems are used for STO and SBC operations, then safety and reliability are improved, but device complexity and integration burden increase
Solution Approach 1:
The patent combines STO and SBC control functions into a single integrated control system with unified circuitry and monitoring mechanisms. The control board integrates motor control circuits, brake control circuits, and safety monitoring functions into one consolidated architecture, reducing the number of separate components while maintaining safety integrity through shared communication buses and coordinated control logic.
Solution Approach 2:
The control system is designed as a universal platform that handles multiple safety functions (STO, SBC, emergency stopping, overspeed protection) through a single multi-functional architecture. The same control board and monitoring circuits manage diverse safety operations across different power levels and drive configurations, eliminating the need for separate dedicated systems for each safety function.
2Reliability
If SIL3 certification requirements are met for STO and SBC operations, then safety compliance is improved, but certification costs and complexity increase
Solution Approach 1:
The control system is segmented into functionally independent but integrated modules, each handling specific safety functions with dedicated monitoring circuits. The segmentation allows for modular certification where each module can be validated independently while maintaining overall system integrity, reducing the complexity of comprehensive certification by enabling staged validation of individual safety functions.
Solution Approach 2:
The patent introduces intermediary monitoring circuits and communication interfaces that mediate between control commands and safety-critical actuators. These intermediary elements provide isolation, validation, and fault detection layers that simplify certification by creating clearly defined safety boundaries and enabling standardized verification of safety function implementation across different hardware configurations.
3Adaptability or versatility
If a scalable architecture is implemented across various drive portfolios, then adaptability is improved, but device complexity increases
Solution Approach 1:
The control board is designed as a universal platform with configurable parameters and standardized interfaces that accommodate multiple power levels and drive types. The same hardware architecture supports different motor ratings, brake configurations, and safety requirements through software configuration and parameter setting, eliminating the need for separate dedicated control boards for each application variant.
Solution Approach 2:
The scalable architecture achieves adaptability through parameter changes rather than structural modifications. The control system uses configurable parameters for power ratings, current limits, brake characteristics, and safety function activation that can be adjusted via software or dip switches, allowing a single hardware design to serve multiple applications without increasing physical complexity.
Data Source
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AI summary
A control system for safe torque off (STO) operation and safe brake control (SBC) operation is provided, including a motor, a brake and a drive safety interface board (DSIB) including a first portion of a first circuitry for accomplishing the STO operation a first portion of a second circuitry for accomplishing the SBC operation and a monitoring circuitry for monitoring the STO and SBC operations.