Current Transformer AC Voltage Detection Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power supply apparatuses for heat fixing devices in image forming apparatuses face challenges in achieving highly accurate power supply control at a low cost, particularly in detecting AC voltage and zero cross timing, which affects the efficiency and accuracy of power distribution.
Innovation Solution
A power supply apparatus is designed with a conversion element, a voltage detection unit using a current transformer, and a zero cross detection unit to convert AC voltage into current and detect AC voltage output, enabling precise power supply control with a simple circuit configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a bidirectional thyristor (triac) is used to control AC voltage supplied to the heat fixing device, then power supply control can be achieved, but the circuit complexity increases and detection accuracy of zero cross timing deteriorates
Solution Approach 1:
The patent introduces a current transformer as an intermediary device to detect AC voltage and zero cross timing. The current transformer converts the high-voltage AC signal into a low-voltage signal that can be safely and accurately detected by the control circuit, eliminating the need for complex high-voltage detection circuits while maintaining control accuracy.
Solution Approach 2:
The patent replaces mechanical or complex electronic voltage detection methods with a magnetic field-based current transformer approach. The current transformer uses electromagnetic induction to detect voltage characteristics through current transformation, providing a simpler and more reliable detection mechanism.
2Measurement precision
If complex detection circuits are used to achieve accurate zero cross timing detection, then detection accuracy improves, but power consumption increases
Solution Approach 1:
The current transformer serves as a passive intermediary that transforms the AC voltage signal into a proportional current signal without requiring active power consumption for detection. The electromagnetic induction process occurs naturally with the AC signal, eliminating the need for powered detection circuits.
Solution Approach 2:
The detection system leverages the periodic nature of AC power supply to achieve zero cross timing detection. By detecting the natural zero-crossing points of the AC waveform through the current transformer, the system achieves accurate timing without requiring continuous active monitoring or additional power consumption.
3Device complexity
If direct AC voltage detection is performed without conversion, then circuit simplicity is maintained, but detection accuracy and safety deteriorate
Solution Approach 1:
The current transformer acts as a safe intermediary that isolates the detection circuit from direct high-voltage exposure while providing accurate voltage information. The transformer's magnetic coupling allows voltage detection without direct electrical connection, improving both safety and measurement accuracy.
Solution Approach 2:
The patent changes the parameter being detected from direct voltage to proportional current through the current transformer. This parameter transformation allows for more accurate and safer detection, as the transformed current signal has lower impedance and can be measured more precisely by standard detection circuits.
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 allows for highly accurate power supply control with reduced power consumption and improved detection accuracy of zero cross timing, enabling efficient and cost-effective power management for heat fixing devices.
Implementation Method 1
a first line and a second line to each of which an AC voltage is input from an AC power supply; a conversion element configured to convert the AC voltage to be input to the first line or the second line into a current corresponding to the AC voltage; a voltage detection unit including a first current transformer
Data Source
AI summary
The power supply apparatus includes a first line and a second line to each of which an AC voltage is input from an AC power supply; a conversion element configured to convert the AC voltage to be input to the first line or the second line into a current corresponding to the AC voltage; a voltage detection unit including a first current transformer, the first current transformer including a primary winding and a secondary winding, the voltage detection unit being configured to detect an AC voltage output from the secondary winding of the first current transformer through supply of the current converted by the conversion element to the primary winding; and a zero cross detection unit configured to detect a zero cross timing of the AC power supply based on the AC voltage detected by the voltage detection unit.