Single Microprocessor Inverter Control with Dual Estimation Safety Logic
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Solution Overview
Problem
Current power converters require redundant architectures involving two microprocessors to achieve a SIL level of 2 for functional safety in speed control, which is costly and inefficient.
Innovation Solution
A secure control system for power converters that integrates functional safety functions by using a control unit with electronic and software processing circuits to estimate current and voltage signals, comparing these signals with stored safety parameters to inhibit the inverter module, thereby achieving SIL level 2 without the need for two microprocessors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two microprocessors are used in parallel for speed monitoring, then functional safety (SIL level 2) is achieved, but device complexity and cost increase
Solution Approach 1:
The patent merges the safety monitoring function into the single microprocessor by implementing a dual estimation architecture where one estimation path uses electronic circuits and the other uses software algorithms. Both paths process the same input signals (current, voltage, speed) and their outputs are compared by a safety logic unit within the same processor, eliminating the need for a second microprocessor while maintaining SIL 2 functionality.
Solution Approach 2:
The single microprocessor is designed to perform multiple functions: it executes the primary control algorithm, runs two independent speed estimation paths (electronic and software-based), and implements the safety comparison logic. This multi-functional design allows one processor to replace what traditionally required two processors, reducing system complexity while maintaining safety.
2Reliability
If redundant devices are implemented on converter circuits, then functional safety requirements are satisfied, but hardware requirements and cost increase
Solution Approach 1:
The patent creates a virtual copy of the speed estimation function through software implementation. Instead of duplicating hardware circuits, it implements a software-based estimation algorithm that mirrors the electronic circuit estimation logic. This software copy is then compared with the electronic circuit output by the safety logic, providing redundancy without additional physical hardware.
Solution Approach 2:
The patent replaces physical hardware redundancy with computational redundancy. Rather than using two separate microprocessors or duplicate electronic circuits, it uses software algorithms running on a single processor to create the redundant estimation path. This substitution of mechanical/hardware redundancy with software-based redundancy reduces component quantity while maintaining safety functionality.
Data Source
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AI summary
The system has a software processing unit (21) comprising a software estimation module (210) estimating a pulsation value (Val1p-sw) or a phase value. A electronic processing unit (20) comprises an electronic comparison unit (204) arranged to compare a current pulsation value (Ip-Hw) or a phase estimated by an electronic processing circuit (200), a tension pulsation value (Up-Hw) or phase estimated by another electronic processing circuit (201) and the pulsation value or the phase estimated by the software module. The comparison unit comprises an inhibition channel (C1) of an inverter module (INV) of a power converter. The power converter is a type of speed variator.