AC/DC Converter X-Capacitance Discharge Control
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Solution Overview
Problem
AC/DC converters face challenges in quickly and safely discharging residual voltage stored in x-capacitance when the AC input signal is interrupted, requiring a controlled discharge mechanism to prevent damage and ensure safe operation.
Innovation Solution
A controller with a second DC discharge circuit and logic that monitors a DC sense signal to determine loss of the AC input signal, turning on the discharge circuit for a predetermined time and maintaining it on until the voltage decreases to a safe level, ensuring controlled discharge of x-capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a discharge circuit is activated to quickly discharge x-capacitance, then the discharge speed is improved, but the risk of voltage spike damage increases
Solution Approach 1:
The controller activates the discharge circuit immediately upon detecting AC input loss, performing the discharge action in advance before voltage levels become dangerous. This preliminary action prevents voltage buildup while controlling the discharge rate to avoid spikes through regulated current flow.
Solution Approach 2:
The controller continuously monitors the voltage across the x-capacitor during discharge and adjusts the discharge circuit operation based on feedback signals. This closed-loop control ensures the voltage is reduced to safe levels without creating dangerous voltage spikes, balancing speed and safety.
2Reliability
If the discharge circuit remains on for an extended period, then complete discharge is ensured, but energy loss increases
Solution Approach 1:
The controller monitors voltage levels across the x-capacitor and automatically deactivates the discharge circuit when the voltage reaches a predetermined safe threshold. This feedback-controlled approach ensures complete discharge to safe levels while minimizing energy loss by stopping the discharge process at the appropriate moment rather than maintaining continuous discharge.
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
Effectively manages the discharge of x-capacitance, ensuring safe operation and compliance with safety standards by maintaining the AC/DC converter in a stable state after AC input signal loss, preventing damage and enabling timely restarts.
Implementation Method 1
a second DC discharge circuit (28) having a controllable switching element (283) for switching the second DC discharge circuit (28) on and off, wherein the second DC discharge circuit (28) is operative to receive a DC discharge current from the first DC discharge circuit (12, 15)
Data Source
AI summary
An AC/DC converter is operative to receive, via AC input terminals, an AC input signal and to transform the AC input signal into a DC output signal. The AC/DC converter comprises a first DC discharge circuit coupled to AC input terminals. The controller comprises a second DC discharge circuit having a controllable switching element for switching the second DC discharge circuit on and off. The second DC discharge circuit is operative to receive a DC discharge current from the first DC discharge circuit; logic associated with the AC/DC converter repeatedly: receives a DC sense signal from the second DC discharge circuit and determines, based on the value of the DC sense signal within a predetermined measurement time period, loss of the AC input signal. In response to determining loss of the AC input signal, the logic controls activation of the second DC discharge circuit depending on the DC sense signal.