Three-Winding Power Converter Relay Isolation for PFC Short Circuits
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Solution Overview
Problem
In power conversion apparatuses for electrified vehicles, a short circuit in the PFC-side circuit can cause an overcurrent to flow through the transformer, affecting both the main battery-side and auxiliary battery-side circuits.
Innovation Solution
The power conversion apparatus includes a transformer with three windings and switching circuits connected to each winding. A relay is provided in the power line between the smoothing capacitor and the first winding, allowing for selective interruption of the current path, thereby preventing overcurrents if a short circuit occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a relay is added to interrupt the current path between the smoothing capacitor and the first winding, then overcurrent protection is improved, but device complexity increases
Solution Approach 1:
The relay is pre-configured in the circuit between the smoothing capacitor and the first winding of the transformer, positioned to automatically interrupt the current path when a short circuit occurs in the PFC-side circuit. This preliminary arrangement ensures that protection action is immediately available without requiring additional control logic or complex detection systems.
Solution Approach 2:
The relay acts as an intermediary protective device that isolates the smoothing capacitor from the transformer winding when a fault occurs. By introducing this intermediate component, the patent creates a simple yet effective barrier that prevents overcurrent from propagating through the transformer to the main battery-side and auxiliary battery-side circuits, thereby protecting the overall system with minimal added complexity.
2Reliability
If the relay is positioned between the smoothing capacitor and the first winding, then protection effectiveness is improved, but manufacturing cost increases
Solution Approach 1:
The relay is implemented as a simple, inexpensive protective component that can be easily manufactured and integrated into the power conversion apparatus. Rather than using complex expensive protection systems, the patent employs a straightforward relay mechanism that provides effective overcurrent protection at minimal cost, aligning with the principle of using simple, affordable components for safety functions.
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
This configuration effectively prevents overcurrents in the main battery-side and auxiliary battery-side circuits by interrupting the current path when a short circuit is detected, ensuring safe and efficient power transfer.
Implementation Method 1
a transformer including a first winding, a second winding, and a third winding... electric power is transferred via the transformer among an external power supply, a main battery, and an auxiliary battery
Implementation Method 2
a power factor correction circuit configured to improve a power factor of alternating-current power input from the external power supply
Implementation Method 3
a smoothing capacitor configured to smooth a voltage of direct-current power output from the power factor correction circuit
Data Source
AI summary
A power conversion apparatus includes a transformer including a first winding, a second winding, and a third winding, a first switching circuit connected between an external power supply and the first winding, a second switching circuit connected between a main battery and the second winding, and a third switching circuit connected between an auxiliary battery and the third winding. The first switching circuit includes a power factor correction circuit, a smoothing capacitor configured to smooth a voltage of direct-current power output from the power factor correction circuit, and a relay provided in a power line between the smoothing capacitor and the first winding.