Power Converter Safety Logic Module for Motor Control
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Solution Overview
Problem
Conventional power converters for electrical machines in motor vehicles can malfunction, leading to unsafe operating conditions due to incomplete or faulty control signal generation, potentially causing road safety issues by misinterpreting speed requests.
Innovation Solution
A power converter system with a control circuit divided into primary and secondary parts, including a control logic module and a safety logic module, which generates error signals to detect and correct malfunctions by comparing actual and target operating states, ensuring safe operation by stopping the power supply if deviations are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a control logic module is used to generate control signals for power switches, then the power converter can efficiently control the electrical machine, but the system may malfunction leading to unsafe operating conditions
Solution Approach 1:
A safety logic module is introduced as an intermediary between the control logic module and the power switches. The safety logic module receives control signals from the control logic module, verifies their correctness, and only passes them to the power switches if they are valid. This intermediary layer prevents faulty control signals from causing unsafe operations while maintaining the efficiency of the control logic module.
Solution Approach 2:
The safety logic module implements a feedback mechanism by monitoring the control signals generated by the control logic module and comparing them against expected operational parameters. When deviations or errors are detected, the safety logic module generates error signals that feed back to prevent unsafe operations, thus ensuring reliability without compromising control efficiency.
2Reliability
If the control circuit is divided into primary and secondary parts with galvanic isolation, then electrical safety is improved, but system complexity increases
Solution Approach 1:
The control circuit is segmented into a primary control logic module and a secondary safety logic module, with galvanic isolation between them. This segmentation allows the system to maintain electrical safety through isolation while distributing functions across separate modules. The segmentation reduces the complexity burden on any single module and improves overall system reliability.
3Reliability
If error detection and correction mechanisms are added to detect control logic malfunctions, then operational safety is enhanced, but device complexity increases
Solution Approach 1:
The safety logic module serves as an intermediary that incorporates error detection and correction mechanisms. It receives control signals, verifies their validity through built-in monitoring functions, and either passes them through or generates error signals to prevent unsafe operations. This approach enhances operational safety while concentrating the complexity in a dedicated safety module rather than distributing it throughout the entire control system.
Data Source
Figure 1
AI summary
The converter (1) has a first control logic device (14) attached to a request line (31) and a sensor conductor (29). A second control logic device (15) is attached to a request line (32) for a request signal (R) and another sensor conductor (30) for sensor signals (S1'-S5'). Safety logic devices (16, 17) are arranged on the control logic device by an error line (33). The safety logic devices modify a set of control signals (TOP-PWM, BOT-PWM) on the basis of a control logic error signal (ERR1) such that supply of operation voltage to an electric machine is stopped. An independent claim is also included for a method for operating a power converter for feeding an electric machine with operation voltage.