AC to DC Rectifier Circuit with Dynamic Voltage Detection
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Solution Overview
Problem
Existing AC to DC rectifier circuits in low power applications sink large amounts of current from the AC mains near the peak of the sine wave, leading to grid voltage waveform distortion, and are not suitable for use with capacitive loads.
Innovation Solution
A DC to AC circuit comprising a rectifier circuit, a voltage detecting circuit, a constant current source, and an output circuit, where the voltage detection circuit adjusts current flow based on the instantaneous output voltage, allowing current absorption during the rising and falling phases of the AC wave instead of near the peak, and using a constant current source to regulate output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a large capacitance CL is used to smooth the output voltage, then the output voltage becomes smoother, but the conduction time becomes shorter and the charging current becomes larger, causing grid voltage waveform distortions
Solution Approach 1:
The patent uses a dynamic control approach where the switching state of the rectifier diode is dynamically adjusted based on the instantaneous relationship between output voltage and input voltage. The diode switches between conducting and non-conducting states to regulate current flow, transforming the static large-capacitor smoothing approach into a dynamic switching control system that maintains voltage smoothness while preventing current surges that cause grid distortion
Solution Approach 2:
The patent implements a feedback mechanism where the switching decision of the rectifier diode is based on real-time detection of the output voltage and input voltage relationship. When the output voltage reaches a predetermined level, the diode is turned off to prevent overcharging and current surges, creating a closed-loop control system that automatically regulates current flow to avoid grid voltage waveform distortions while maintaining smooth output voltage
2Productivity
If the rectifier circuit sinks large current near the peak of the sine wave, then the power transfer efficiency is improved, but the grid voltage waveform distortion increases
Solution Approach 1:
The patent applies preliminary action by turning off the rectifier diode in advance when the output voltage reaches a predetermined level before the input voltage peak. This preemptive switching prevents the circuit from sinking excessive current near the peak of the sine wave, thereby maintaining power transfer efficiency while avoiding the harmful effect of grid voltage waveform distortion that would occur with conventional continuous conduction
3Device complexity
If a conventional rectifier circuit is used, then the circuit structure is simple, but it is not suitable for use with capacitive loads due to current waveform distortion
Solution Approach 1:
The patent transforms the static conventional rectifier circuit into a dynamic switching circuit where the rectifier diode's conduction state is actively controlled based on voltage relationships. This dynamic approach enables the circuit to adapt to capacitive loads by regulating current flow timing, improving capacitive load compatibility while maintaining relative structural simplicity through the use of existing rectifier components with added control logic
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 prevents sudden changes in current signal, reducing interference with the city mains and maintaining a stable output voltage, while working effectively with capacitive loads and avoiding grid voltage distortion.
Implementation Method 1
The process of making the AC power turn into unidirectional power is called rectification
Implementation Method 2
a voltage detecting circuit, a constant current source
Implementation Method 3
using a constant current source to regulate output
Data Source
AI summary
An AC to DC circuit includes a rectifier circuit, a voltage detecting circuit, the current source and the output circuit. The rectifier circuit converts the AC power to pulsating DC. The constant current source provides current to the voltage detection circuit and to the control port of the output circuit. The current passing throughout the constant current source is the sum of the current flowing to the voltage detection circuit and to the output circuit. The voltage detection circuit increases with the instantaneous value of the output voltage of the rectifier circuit, it absorbs more current from the current provided by the constant current source and less current flows from the constant current source to the control port of the output circuit. The output circuit amplifies the current of the control port and outputs it to power the load. The AC to DC circuit of the present invention can rectify the portion of an alternating input voltage below a sine peak of the alternating current, working at a sine wave ascending area and a sine wave descending area, and it can carry a capacitive load.