Pre-Charge Circuitry for Stable DC Voltage in Power Converters
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Solution Overview
Problem
Existing electric power converters face issues such as undershoot and overshoot of DC voltages during energy transfer due to unregulated capacitor charging, which can lead to transformer saturation and damage to loads, and existing solutions like Zener diodes are costly, bulky, and unreliable, especially for asymmetrical voltage scenarios.
Innovation Solution
A pre-charge circuitry is introduced to charge the capacitor before entering the energy transfer mode, using components like current generators, voltage dividers, and comparators to control the charging process, ensuring the capacitor reaches a threshold voltage or time before transitioning to energy transfer, thereby preventing voltage irregularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If unregulated capacitor charging is used during energy transfer, then the charging process is simple and fast, but voltage undershoot and overshoot occur leading to transformer saturation and load damage
Solution Approach 1:
The patent applies preliminary action by charging the capacitor through a pre-charge circuit before the energy transfer mode is activated. The pre-charge circuit includes a pre-charge switch and resistor that charge the capacitor to a predetermined voltage level before main operation begins, preventing voltage undershoot and overshoot during subsequent energy transfer operations.
2Reliability
If Zener diodes are used to regulate voltage, then voltage stability is improved, but the device becomes costly, bulky, and unreliable
Solution Approach 1:
The patent extracts the voltage regulation function from traditional bulky components like Zener diodes and implements it through a compact pre-charge circuit using standard switches and resistors. This eliminates the need for expensive and large voltage regulation components while maintaining voltage stability through controlled pre-charging.
Solution Approach 2:
The patent replaces expensive, bulky Zener diodes with inexpensive standard electronic components (switches and resistors) that can be easily integrated into the circuit. These simpler components achieve the same voltage stabilization function without the drawbacks of cost, size, and reliability issues associated with Zener diodes.
3Reliability
If existing pre-charge solutions are used, then some voltage control is achieved, but they fail to reliably prevent undershoot and overshoot in asymmetrical voltage scenarios
Solution Approach 1:
The patent addresses asymmetrical voltage scenarios by implementing a pre-charge circuit specifically designed to handle different voltage levels and conditions on either side of the transformer. The circuit can be configured with appropriate switches and resistors to manage asymmetrical charging requirements, ensuring reliable voltage control regardless of voltage symmetry.
Data Source
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AI summary
An apparatus may include an electric power converter and pre-charge circuitry. The electric power converter may include a first circuit, a second circuit and an energy transfer device. The first circuit may be connected to a power supply. The second circuit may be connected to a load. The energy transfer device may have a first side connected to the first circuit and a second side connected to the second circuit. The pre-charge circuitry may be connected to a capacitor of the first circuit. The capacitor may be connected to the first side of the energy transfer device. The pre-charge circuitry may be configured to charge the capacitor during a pre-charge mode of the electric power converter. The electric power converter may be configured to exit the pre-charge mode and enter an energy transfer mode responsive to a charge level of the capacitor reaching a threshold pre-charge level.