Dual-Frequency Power Supply Switching to Suppress Surge Currents
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Solution Overview
Problem
Existing dual-frequency power-supply apparatuses for high-frequency quenching processes lack durability due to surge currents and inefficient heat distribution in complex-shaped workpieces.
Innovation Solution
A dual-frequency power-supply apparatus that alternately outputs low-frequency and high-frequency alternating currents, controlled by an inverter and controller to manage output periods and intermissions, ensuring the length of intermissions exceeds the time for polarity reversal, reducing surge currents and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the power supply alternately outputs first alternating current with first frequency and second alternating current with second frequency for heating complex-shaped workpieces, then heating effectiveness is improved, but surge currents occur reducing durability
Solution Approach 1:
The controller sets the intermission period longer than the time until polarity reversal, performing preliminary discharge of the smoothing capacitor before switching frequencies. This preliminary action prevents surge currents from occurring when switching between first and second alternating currents, thereby maintaining durability while preserving heating effectiveness
2Reliability
If the intermission period is set longer than polarity reversal time to prevent surge currents, then durability is improved, but cycle time increases
Solution Approach 1:
The controller dynamically adjusts the intermission period based on the polarity reversal time parameter, setting it longer than the polarity reversal time. This parameter change ensures sufficient discharge time to prevent surge currents and improve durability, while the intermission period is optimized to minimize cycle time extension
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 provides a high-durability dual-frequency power-supply apparatus that effectively heats complex-shaped workpieces, reducing damage from surge currents and improving heating efficiency.
Implementation Method 1
an inverter that converts a direct current into the first alternating current and the second alternating current
Implementation Method 2
a first matching box that has a first matching transformer and is capable of receiving the output current of the power supply to output the first alternating current, and a second matching box that has a second matching transformer
Implementation Method 3
a coil that receives the first alternating current and the second alternating current from the dual-frequency power-supply apparatus
Implementation Method 4
a high-frequency quenching process using high-frequency waves
Data Source
AI summary
Provided are a dual-frequency power-supply apparatus, a high-frequency heating apparatus, and a high-frequency quenching apparatus having a high durability.A dual-frequency power-supply apparatus 1 includes a power supply 10 that alternately outputs a low-frequency current and a high-frequency current. The power supply 10 has an inverter 30 that converts a direct current into the low-frequency current and the high-frequency current and a controller 40 that controls the inverter 30. The controller 40 repeats, in this order, a first output period T11 in which the low-frequency current is output, a first intermission T12 in which output is stopped, a second output period T13 in which the high-frequency current is output, and a second intermission T14 in which output is stopped. The controller 40 sets the length of the first intermission T12 longer than a time Ta until the polarity of the output voltage of the power supply 10 is reversed fourthly after transition from the first output period T11 to the first intermission T12.