Inverter Control Circuit for Rapid Switch Failure Diagnosis
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Solution Overview
Problem
Existing power conversion devices for motor systems face challenges in quickly identifying failures in switching elements and windings, particularly in inverter systems, which hampers efficient motor operation and safety in redundant designs.
Innovation Solution
A power conversion device with a control circuit that generates specific control signals to diagnose failures in low-side and high-side switches by measuring phase voltages and referencing a lookup table, allowing for rapid identification of switch failures and winding disconnections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional failure detection methods using measured current and voltage values are used, then failure detection can be performed, but more time is consumed for failure detection and identification of the failure point
Solution Approach 1:
The patent applies preliminary action by pre-establishing a correspondence table that maps switching element failure patterns to specific n-phase voltage level patterns. Instead of performing complex real-time analysis of current and voltage measurements, the system pre-computes and stores the expected voltage patterns for each possible failure scenario. During operation, the control circuit simply compares measured voltage levels against this pre-established table, enabling rapid failure identification without consuming additional processing time.
Solution Approach 2:
The patent substitutes complex computational analysis (mechanical/systematic processing of current and voltage measurements) with a simpler lookup-based approach. By replacing the need for real-time mathematical analysis of multiple electrical parameters with a direct voltage level pattern matching against a pre-stored correspondence table, the system achieves faster failure detection while maintaining accurate identification of the failed switching element.
2Reliability
If two inverters are provided for redundant design, then safe operation can be continued even when some parts fail, but it is required to identify a failure point within as short a time as possible
Solution Approach 1:
The patent applies preliminary action by pre-establishing a correspondence table that maps switching element failure patterns to specific n-phase voltage level patterns. Instead of performing complex real-time analysis of current and voltage measurements, the system pre-computes and stores the expected voltage patterns for each possible failure scenario. During operation, the control circuit simply compares measured voltage levels against this pre-established table, enabling rapid failure identification without consuming additional processing time.
Solution Approach 2:
The patent implements feedback by continuously monitoring the n-phase voltages at the motor terminals and comparing the measured voltage pattern against the pre-stored correspondence table. When a mismatch is detected, the system immediately identifies the specific failure pattern based on the voltage level comparison, providing rapid feedback about the failure condition. This enables the redundant inverter system to quickly switch to backup operation.
3Measurement precision
If conventional failure detection techniques are used in single inverter devices, then disconnection and short circuit of wiring can be detected, but it is difficult to identify which switching element among a plurality of switching elements has failed
Solution Approach 1:
The patent applies preliminary action by pre-establishing a correspondence table that maps switching element failure patterns to specific n-phase voltage level patterns. Instead of performing complex real-time analysis of current and voltage measurements, the system pre-computes and stores the expected voltage patterns for each possible failure scenario. During operation, the control circuit simply compares measured voltage levels against this pre-established table, enabling rapid failure identification without consuming additional processing time.
Solution Approach 2:
The patent applies segmentation by dividing the failure detection problem into distinct, identifiable patterns. Each switching element failure (open or short circuit) produces a unique n-phase voltage level pattern that is stored in the correspondence table. By segmenting the overall failure detection task into specific, pre-characterized failure modes, the system can identify which specific switching element has failed based on which voltage pattern is observed, rather than dealing with a undifferentiated failure signal.
Data Source
AI summary
A power conversion device includes a first inverter and a control circuit that controls an on/off operations of switches in the first inverter and diagnoses disconnection failures of n-phase windings, where n is an integer of three or more. The control circuit generates a control signal to turn off all of n low-side switches and n high-side switches, supplies the control signal to the n low-side switches and the n high-side switches and measures the n-phase voltages that change depending on patterns of on failures of the switches, and executes a first failure diagnosis to diagnose the on failures of the n low-side switches and the n high-side switches based on the measured n-phase voltages by referring to a table associating the patterns of the on failures of the switches with n-phase voltage levels.