Power Off Delay Circuit Using Boost Transformer
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Solution Overview
Problem
Large capacitance capacitors in electronic devices often fail to provide sufficient power off delay time due to increased power requirements of load circuits, especially in high-function and high-speed processes.
Innovation Solution
A power off delay circuit utilizing a boost transformer circuit with a capacitor, diodes, and switch branches, along with a PWM controller and feedback circuit, which boosts power when the input is off and charges when on, reducing capacitance needs and extending power off delay time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If capacitor capacitance is increased to provide enough power when power supply is off, then power supply capacity is improved, but power off delay time is reduced
Solution Approach 1:
The capacitor is charged to a higher voltage than the normal operating voltage before the power supply is turned off. This preliminary charging action stores sufficient energy in the capacitor to maintain power supply to the load circuit for an extended delay period after the main power is disconnected, thereby resolving the contradiction between power supply capacity and power off delay time
Solution Approach 2:
The invention changes the voltage parameter of the capacitor from the normal operating voltage to a higher charging voltage. By increasing the voltage parameter, the energy storage capacity of the capacitor is enhanced without requiring larger capacitance, thus extending the power off delay time while maintaining adequate power supply capability
2Quantity of substance
If capacitor capacitance is increased to provide enough power when power supply is off, then energy storage capacity is improved, but device complexity and size are increased
Solution Approach 1:
Instead of increasing capacitance, the invention changes the voltage parameter by which the capacitor is charged. The capacitor is charged to a higher voltage than the normal operating voltage through a charging circuit, thereby increasing energy storage (E=1/2CV²) without increasing capacitance value, which avoids increasing device complexity and size
Solution Approach 2:
A charging circuit is introduced as an intermediary component that temporarily charges the capacitor to a higher voltage before power off. This intermediary mechanism allows the capacitor to store sufficient energy for extended delay without requiring larger capacitance, thus avoiding increased device complexity
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 solution effectively extends the power off delay time and enhances energy utilization by reducing the required capacitance while maintaining sufficient power supply to load circuits, such as central processing units.
Implementation Method 1
a boost transformer circuit with a capacitor, diodes, and switch branches, along with a PWM controller and feedback circuit, which boosts power when the input is off
Data Source
AI summary
A power off delay circuit includes a first diode with an anode receiving input power and a boost transformer circuit connected to a cathode of the first diode. The boost transformer circuit outputs power signals to a load circuit, and includes a capacitor, a primary winding, a first secondary winding, and a second secondary winding. The capacitor is charged when an input power is on, and discharges when the input power is off. The first secondary winding boosts power flowing through the primary winding and the first switch branch to charge the capacitor via the third switch branch when the input power is on. The capacitor discharges via the second secondary winding and the fourth switch branch when the input power is off, and the primary winding boosts discharging power of the capacitor, and outputs boosted discharging power to the load circuit via the second switch branch.