High-Frequency Heating Device Power Factor Correction
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Solution Overview
Problem
Commercially available microwave heating cookers with additional cooking functions face issues due to the limited lifespan of large-capacity electrolytic capacitors used in power factor correction, which also increase manufacturing costs and circuit complexity, and existing solutions do not adequately improve the input power factor without using such capacitors.
Innovation Solution
A high-frequency heating device that includes an alternating current power source, an oscillator, an amplitude modulation unit, and a power supply unit, where the high-frequency signal is modulated in synchronism with the half-period of the AC power source, allowing for improved input power factor without large-capacity electrolytic capacitors, using a configuration that includes a switching converter and a small-capacity film capacitor for enhanced heat resistance and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large-capacity electrolytic capacitor is used for power factor correction, then the input power factor is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The invention extracts and eliminates the large-capacity electrolytic capacitor from the power factor correction circuit, replacing it with a capacitor-free topology that uses switching elements and reactive components to achieve power factor improvement without the problematic capacitor
Solution Approach 2:
The invention introduces a switching element (transistor or thyristor) as an intermediary component to control the current flow and reactance in the circuit, enabling power factor correction through active switching rather than passive capacitor storage
2Reliability
If a large-capacity electrolytic capacitor is used for power factor correction, then the input power factor is improved, but the manufacturing cost increases
Solution Approach 1:
The invention replaces the expensive, temperature-sensitive electrolytic capacitor with cheaper, more durable components such as film capacitors or inductors that have longer operational life and better temperature characteristics, reducing manufacturing cost and improving reliability
3Reliability
If a large-capacity electrolytic capacitor is used in a high-temperature environment, then the power factor correction function is maintained, but the capacitor lifespan decreases
Solution Approach 1:
The invention converts the harmful effect of high temperature on electrolytic capacitors into a benefit by eliminating the capacitor entirely and using a circuit topology (reactive power factor correction) that actually benefits from or is neutral to high-temperature environments, extending device lifespan
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 improves the input power factor of the AC power source, extends the lifespan of the heating device, and reduces manufacturing costs by using a small-capacity film capacitor, which is more resistant to high-temperature environments compared to large-capacity electrolytic capacitors.
Implementation Method 1
an amplitude modulation unit that modulates an amplitude of the high-frequency signal with a signal wave that is in synchronism with a half-period of a cycle of the alternating current power source
Implementation Method 2
an amplifier that amplifies the high-frequency signal modulated in amplitude by the amplitude modulation unit
Implementation Method 3
an antenna that radiates the power into a cooking chamber in the form of a microwave
Implementation Method 4
A microwave heating cooker (high-frequency heating device) is a device that heats a dielectric object to be heated by means of high-frequency dielectric heating
Data Source
AI summary
A microwave heating cooker (1) includes a high-frequency power source (10). The high-frequency power source (10) includes a first semiconductor amplification circuit (amplifier) (3), a second semiconductor amplification circuit (amplifier) (4), an antenna (power supply unit) (5), a high-frequency generation unit (6), a commercial power source (alternating current power source) (7), a first full-wave rectification circuit (11), and a switching converter (12). The high-frequency generation unit (6) is configured from a commercial transformer (20), a second full-wave rectification circuit (21), resistors (22 and 23), an amplifier (24), an analog multiplier (amplitude modulation unit) (25), and a high-frequency oscillator (oscillator) (26), among others. The analog multiplier (25) modulates the amplitude of the output voltage from the high-frequency oscillator (26) with a signal wave that is in synchronism with a half-period of the cycle of the commercial power source (7).