Protective Circuit for Charging Apparatus Polarity Reversal
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Solution Overview
Problem
Existing DC voltage charging apparatuses are prone to short circuits and damage due to polarity reversal, with known solutions incurring power loss from fuses and diodes during normal operation.
Innovation Solution
A protective circuit using contactors as switches and a precharging circuit to balance voltage, preventing polarity reversal by switching only when the potential difference is within a safe range, eliminating the need for semiconductor switches and fuses, thereby minimizing power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fuse and diode are provided in the charging apparatus to protect against polarity reversal, then protection against short circuit and damage is achieved, but power loss occurs during normal operation due to electrical resistance
Solution Approach 1:
The invention extracts and removes the fuse and diode components from the charging apparatus. By eliminating these passive protective components, the patent achieves protection against polarity reversal through active control means (controller and switching elements) while removing the source of power loss associated with the electrical resistance of fuses and diodes during normal operation.
Solution Approach 2:
The invention replaces the passive mechanical/electrical protective system (fuse and diode) with an active electronic control system. The controller monitors polarity and uses switching elements to prevent reverse current flow, substituting the resistive protection mechanism with a controlled switching mechanism that minimizes power loss.
2Reliability
If semiconductor switches are used in the power branches for protection, then polarity reversal protection is achieved, but additional switching elements increase device complexity and power loss
Solution Approach 1:
The invention extracts and removes semiconductor switches from the power branches. Instead of placing switching elements directly in the high-power current path, the patent uses a bridge circuit configuration where switching elements are controlled by a separate controller, reducing device complexity and eliminating unnecessary power losses in the power branches.
Solution Approach 2:
The invention introduces a bridge circuit as an intermediary mechanism. The bridge circuit, controlled by a separate controller, acts as a mediator between the power source and the load, enabling polarity reversal protection without requiring semiconductor switches to be directly embedded in the power branches, thus reducing complexity.
3Reliability
If switching elements are placed in the power path for protection, then polarity reversal can be prevented, but power loss increases due to additional resistance
Solution Approach 1:
The invention extracts switching elements from the direct power path. By using a bridge circuit configuration controlled by a separate controller, the patent prevents reverse current flow without placing switching elements in the main power conduction path, thereby eliminating the additional resistance and associated power loss that would result from having switching elements directly in the power path.
Data Source
AI summary
A protective circuit for a DC voltage charging apparatus has a first input, a first output, a second input, a second output, a controllable first switch, a controllable second switch and a first circuit. The first output can be electrically connected to the first input by the controllable first switch and the second output can be electrically connected to the second input by the controllable second switch. The first circuit is electrically connected to the first output and to the second output and said first circuit has a voltmeter, which is designed to identify a voltage value that characterizes the sign of the voltage between the first output and the second output. The first circuit is designed to make it possible to actuate the first switch and the second switch depending on the voltage value.