Power Conversion Device Voltage Sensor Error Detection
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Solution Overview
Problem
Existing power conversion devices fail to detect gain errors, offset errors, and sticking errors in voltage sensors, which can lead to abnormal voltage sensor readings, as feedback control aims to match detected and target values, masking these errors.
Innovation Solution
Incorporating a current sensor to detect current supplied to the circuit with the capacitor and providing abnormality determining means to identify sensor errors based on current values and charging/discharging operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback control is used to match detected and target voltage values, then voltage control accuracy is improved, but voltage sensor abnormalities (gain error, offset error, sticking error) cannot be detected
Solution Approach 1:
The patent introduces an intermediary detection method that does not directly measure voltage but infers voltage sensor abnormalities through current measurements. The current sensor acts as an intermediary to detect anomalies in the voltage sensor by measuring the current during capacitor charging/discharging operations and comparing it with expected current values calculated from circuit parameters and detected voltage.
Solution Approach 2:
The patent replaces direct voltage measurement for abnormality detection with a current measurement-based indirect detection method. Instead of relying on the voltage sensor to detect its own abnormalities (which fails under feedback control), the system uses current sensors and computational logic to substitute the detection function.
2Device complexity
If only voltage sensor is used for detection, then device complexity is reduced, but ability to detect sensor abnormalities is insufficient
Solution Approach 1:
The patent makes the current sensor serve multiple functions: it not only monitors current for power conversion control but also detects voltage sensor abnormalities by comparing measured current with expected current values. This multi-functionality allows reliable abnormality detection without adding dedicated detection hardware.
Solution Approach 2:
The system uses its own operational characteristics (current during capacitor charging/discharging) to self-diagnose voltage sensor abnormalities. The power conversion device monitors its own current consumption patterns during known operational states to detect inconsistencies that indicate sensor failures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the detection of gain errors, offset errors, and sticking errors in voltage sensors, ensuring accurate voltage sensor functionality and preventing erroneous feedback control.
Implementation Method 1
a capacitor (C0) that carries out a charging and discharging operation in accordance with a switching of the switching circuit
Implementation Method 2
a voltage sensor that detects a voltage across the capacitor
Implementation Method 3
a current sensor that detects a current supplied to a circuit including the capacitor
Data Source
AI summary
A power conversion device including an intermediate capacitor that carries out a charging and discharging operation and a voltage sensor that detects a voltage of the intermediate capacitor, and including a current sensor that detects a current flowing in a reactor, and an abnormality determining unit that determines that there is an abnormality of the voltage sensor using a current value calculated based on a detected value from the current sensor, wherein a gain error, an offset error, and a sticking error of the voltage sensor can be detected.