AC-DC Converter Residue Voltage Discharge via Dynamic Switching
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Solution Overview
Problem
Conventional AC-DC converters face challenges in real-time monitoring of AC input voltage trends and efficient discharge of residue DC voltage from high-frequency filter capacitors without excessive power consumption, leading to potential damage and safety risks.
Innovation Solution
A detection unit comprising a JFET and Zener diode with a bleeding resistor-free design, utilizing duty cycles and capacitor charging/discharging mechanisms to monitor input voltage and discharge residue voltage, ensuring efficient power management and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two series resistors are used to form a voltage divider for detecting input voltage changes, then the detection accuracy is improved, but the power consumption increases
Solution Approach 1:
The patent extracts the detection function from the power-consuming voltage divider circuit by using a separate detection unit that monitors the rectified voltage without drawing significant current. The detection unit uses a capacitor to store voltage information and a detection circuit to read the voltage level, eliminating the need for continuous current flow through resistors for detection purposes.
Solution Approach 2:
The patent introduces a capacitor as an intermediary element that stores the rectified voltage information. This capacitor acts as a mediator between the rectified voltage source and the detection circuit, allowing the detection circuit to read voltage levels without directly drawing continuous current from the voltage source, thus reducing power consumption while maintaining detection accuracy.
2Reliability
If a bleeding resistor is used to discharge residue voltage from the high-frequency filter capacitor, then the safety risk is reduced, but the power loss increases
Solution Approach 1:
The patent implements periodic discharge action by controlling the switching element to discharge the residue voltage from the high-frequency filter capacitor only when the AC power is removed. The switching element is turned on during power removal to discharge the capacitor, and turned off during normal operation to prevent continuous power loss. This periodic action maintains safety by discharging dangerous residue voltage while minimizing energy waste by avoiding continuous discharge.
3Object-affected harmful factors
If a bleeding resistor is used to discharge residue voltage, then the electric shock risk is reduced, but the power loss becomes significant under no-load or standby condition
Solution Approach 1:
The patent employs a dynamic switching mechanism that adapts the discharge behavior based on the operational state. The switching element dynamically changes its state: remaining off during normal operation to prevent power loss, and turning on when AC power is removed to discharge residue voltage for safety. This dynamic control optimizes the balance between safety and energy efficiency by adjusting the discharge behavior according to real-time conditions.
Solution Approach 2:
The patent enables the system to self-manage the discharge process by detecting the AC power removal state and automatically activating the switching element to discharge the capacitor. The system monitors its own operational state and triggers the discharge function only when necessary, eliminating the need for continuous external control while ensuring safety and minimizing power loss.
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
The solution effectively monitors AC input voltage trends and discharges residue DC voltage without power loss, enhancing the reliability and safety of AC-DC converters.
Implementation Method 1
A detection unit comprising a JFET and Zener diode with a bleeding resistor-free design, utilizing duty cycles and capacitor charging/discharging mechanisms to monitor input voltage
Implementation Method 2
When the AC power is removed, the high frequency filter capacitor CX will retain a residue DC voltage that equals to the AC voltage at the instance of removal
Implementation Method 3
a switching element connected between the first node and a ground, and is turned on during the removal of the AC voltage, so that the residue voltage is discharged to the ground through the switching element
Data Source
AI summary
The present invention relates to power conversion systems, specifically, it relates to a device for detecting the DC voltage rectified from the AC power supply voltage in an AC-DC converter, primarily used to determine whether the DC input voltage is under a brown-out level and to monitor whether the AC power supply is removed and to discharge the residue DC voltage generated in a high frequency filter capacitor, which is used to filter high frequency noise signals of the AC power supply, during the removal of the AC power.