AC-DC Converter Control Circuit Harmonic Suppression
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Solution Overview
Problem
Conventional AC-DC converters require input voltage sensors and dedicated frequency modulation control circuits to suppress harmonics in the input current, leading to complex and costly circuit designs.
Innovation Solution
A control circuit that combines a power control circuit and a square wave generator to generate a driving signal for the switch circuit, using a frequency modulation control signal to regulate both output power and harmonic suppression without the need for an input voltage sensor or dedicated frequency modulation control circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a dedicated frequency modulation control circuit is used to suppress harmonics of input current, then harmonic suppression is improved, but device complexity increases
Solution Approach 1:
The patent combines the power control circuit and frequency modulation control circuit into a single integrated control circuit. This control circuit simultaneously performs both power control and harmonic suppression functions, eliminating the need for separate dedicated circuits while maintaining effective harmonic suppression of the input current.
Solution Approach 2:
The integrated control circuit is designed to perform multiple functions: it controls the output power of the AC-DC converter and simultaneously suppresses harmonics in the input current. This multi-functional approach replaces what would traditionally require separate specialized circuits, reducing overall device complexity.
2Measurement precision
If an input voltage detection circuit is used for output power control, then power control precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the voltage detection function and power control function into the same control circuit that also handles frequency modulation for harmonic suppression. This integration eliminates the need for a separate input voltage detection circuit while maintaining precise output power control capability.
Solution Approach 2:
The control circuit is designed as a universal multi-functional unit that performs voltage detection, power control, and harmonic suppression simultaneously. This approach achieves precise power control without requiring additional dedicated detection circuits, thereby reducing device complexity.
3Measurement precision
If separate power control circuit and frequency modulation control circuit are used, then control precision is improved, but device complexity increases
Solution Approach 1:
The patent successfully merges the power control circuit and frequency modulation control circuit into a single integrated control circuit. This unified circuit maintains the control precision of both functions while eliminating the complexity associated with having separate dedicated circuits for each function.
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 simplifies the circuit design by eliminating the need for separate harmonic control and input voltage detection, reducing costs and complexity while effectively suppressing harmonics and regulating output power according to user demands.
Implementation Method 1
the resonant capacitor Cb2 and the magnetizing inductance of the primary side of the transformer T100 constitute a resonant circuit
Implementation Method 2
A bridge rectifier 104 is connected to the input side of the AC-DC converter for rectifying the input AC voltage Vin into a full-wave rectified DC voltage
Implementation Method 3
the switch circuit 108 is connected to the primary winding of the transformer T100... the energy stored in the primary side of the transformer T100 is transferred to the secondary side of the transformer T100
Data Source
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AI summary
The invention discloses a control circuit for an AC-DC converter. The control circuit includes a power control circuit for comparing an input current sensing signal generated by sensing an input current of the AC-DC converter and a power level control input and in response thereto generating a frequency modulation control signal, in which the frequency modulation control signal is used to control the output power of the AC-DC converter and suppress harmonics of the input current, and a square wave generator connected to the power control circuit for generating a driving signal used to drive the switch circuit of the AC-DC converter according to the frequency modulation control signal, in which the frequency of the driving signal is varied with the frequency modulation control signal, thereby suppressing harmonics of the input current and regulating the switching frequency the AC-DC converter, and regulating the output power of the AC-DC converter.