DC/DC Bus Fault Isolation for Reverse Connection and Short Circuits
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Solution Overview
Problem
Existing fault isolation methods in photovoltaic power supply systems are inflexible and ineffective in isolating faults caused by reverse connections and short-circuits, often requiring additional components like diodes and fuses, which can be costly and prone to damage, leading to cascading failures and safety risks.
Innovation Solution
A fault isolation apparatus with a controller and circuit breaker that detects voltage and current anomalies on buses connected to DC/DC conversion units, allowing for controlled disconnection to prevent backfeeding and isolate faults without additional diodes or fuses, enhancing reliability and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reverse diode and circuit breaker are added to each DC/DC conversion unit for fault isolation, then fault isolation capability is improved, but device complexity and cost increase
Solution Approach 1:
The controller is designed to perform multiple functions: normal control of DC/DC conversion and fault detection for reverse connections. By integrating fault isolation functionality into the existing controller, the patent avoids adding separate isolation components to each DC/DC unit, thereby reducing overall system complexity while maintaining reliable fault isolation capability through centralized monitoring and control.
2Reliability
If reverse diode is used for fault isolation, then protection against reverse connection is improved, but the diode is prone to damage from backfed energy causing cascading failures
Solution Approach 1:
The patent detects reverse connection faults through voltage polarity detection and uses the controller to open the circuit breaker, preventing backfed energy from damaging components. By converting the potential harm of undetected reverse connections into a controlled protective action, the system eliminates the need for reverse diodes that would otherwise be vulnerable to damage from backfed energy.
Solution Approach 2:
The controller acts as an intermediary between the DC/DC conversion units and the potential harm of reverse connections. By monitoring voltage polarity and controlling the circuit breaker, the controller mediates the energy flow to prevent backfed energy from reaching vulnerable components, thereby protecting the system without requiring additional protective diodes at each unit.
3Reliability
If traditional fault isolation method with diode and fuse is used, then short-circuit fault isolation is achieved, but application flexibility is reduced due to inability to handle reverse connection faults effectively
Solution Approach 1:
The controller is designed to detect both reverse connection faults (through voltage polarity detection) and short-circuit faults (through current monitoring). By integrating multiple fault detection capabilities into a single control system, the patent achieves versatile fault isolation that handles various fault types effectively, greatly improving application flexibility compared to traditional single-purpose isolation methods.
Data Source
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AI summary
This application discloses a fault isolation apparatus, a direct current boost apparatus, and an inverter apparatus, and belongs to the field of power supply technologies. The fault isolation apparatus includes a controller and a circuit breaker. When the circuit breaker is located on a bus connected to a DC/DC conversion unit, if a voltage collected by a first voltage collection terminal is a negative value, it indicates that input or output of the DC/DC conversion unit is reversely connected. In this case, if the circuit breaker is controlled to be opened, the DC/DC conversion unit can be prevented from being connected in series to other parallel DC/DC conversion units. If a voltage collected by a first voltage collection terminal is low and a current collected by a current collection terminal is large, it indicates that the DC/DC conversion unit is short-circuited. In this case, if the circuit breaker is controlled to be opened, another component connected in series to the DC/DC conversion unit can also be prevented from backfeeding energy to the DC/DC conversion unit.