Voltage Detection Device for Power Conversion Systems
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Solution Overview
Problem
In power conversion systems, a failure in the voltage detector that detects the direct current intermediate voltage can lead to an output voltage exceeding the breakdown voltage of switching elements, causing damage due to the lack of immediate failure detection and correction mechanisms.
Innovation Solution
A voltage detection device with a voltage divider circuit using parallel resistor circuits and a multiple voltage detector circuit that selectively outputs voltage values from different points in the divider circuit, allowing for immediate detection of failures by comparing these values to predetermined thresholds, thereby preventing excessive voltage generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single voltage detector is used to monitor direct current intermediate voltage, then the device complexity is low, but the reliability of failure detection is insufficient leading to delayed detection of voltage detector failures
Solution Approach 1:
The voltage divider circuit is divided into multiple resistor circuits (first, second, third resistor circuits) with different resistance values. Multiple voltage detectors detect voltages at different division points simultaneously. This segmentation allows independent detection of different voltage levels, enabling comparison-based failure detection without requiring a single complex detection system.
Solution Approach 2:
The control unit receives detection results from multiple voltage detectors and performs comparison operations. When the detected voltages do not match expected relationships (based on resistor circuit ratios), the system identifies a failure in the voltage detection device. This feedback mechanism enables immediate failure detection and prevents excessive voltage generation.
2Reliability
If multiple voltage detectors are used to detect voltages at different division points, then the reliability of failure detection is improved, but the device complexity increases
Solution Approach 1:
The multiple voltage detectors serve dual purposes: they simultaneously perform normal voltage monitoring functions and failure detection functions. By detecting voltages at different division points during normal operation, the system can compare these readings to detect failures without requiring separate dedicated failure detection hardware, thus achieving multi-functionality with minimal additional complexity.
Solution Approach 2:
The system continuously monitors voltage relationships between different division points during normal operation. This preliminary action of comparing voltage ratios enables the system to detect failures immediately when they occur, rather than waiting for voltage thresholds to be exceeded. The comparison logic is prepared in advance through the control unit's processing capabilities.
3Loss of time
If voltage detection is performed continuously, then the response time for failure detection is immediate, but the energy consumption increases
Solution Approach 1:
The multiple voltage detectors operate continuously during normal system operation, maintaining constant monitoring of voltage relationships. This continuous detection ensures immediate failure detection without interruption. The control unit continuously compares detection results, enabling real-time failure identification while the system is operational, thus maintaining continuity of the useful detection action.
Data Source
AI summary
A detection target voltage is divided by a voltage divider circuit wherein a large number of resistor circuits, each of which is formed by a plurality of resistors being connected in parallel, are connected in series, and the voltage is detected. The output of a multiple voltage detector circuit formed of an operational amplifier, and the like, connected to three arbitrary places in the voltage divider circuit is input into a CPU twice, when the switch is in an on-state and when it is in an off-state. The CPU, based on the two measured voltages, can determine that trouble has occurred when there is, for example, trouble such as a short circuit or disconnection of a resistor of the resistor circuits related to the places connected to the three places in the voltage divider circuit.