Microwave Oven High Voltage Generator Load Balancing
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Solution Overview
Problem
Microwave ovens with full bridge circuits experience significant power losses and thermal issues due to switching elements, leading to inefficiencies and potential thermal problems.
Innovation Solution
A control circuit design for the magnetron that alternates between different operating modes to balance the switching losses across multiple switching elements, using a high-voltage generator with a full bridge and push-pull output stages, where the primary winding is pulsed differently in various phases to distribute power losses evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a full bridge circuit is used to drive the high-voltage transformer, then the microwave oven can operate with high power output, but significant power losses occur in the switching elements leading to thermal problems
Solution Approach 1:
The patent implements periodic switching of the full bridge circuit between different operational modes (Mode 1 and Mode 2). In Mode 1, switches S1 and S2 are activated alternately; in Mode 2, switches S3 and S4 are activated alternately. This periodic alternation ensures that power losses are distributed across all four switching elements over time, preventing any single element from overheating while maintaining high power output capability.
2Temperature
If switching elements are operated in conventional full bridge mode, then high voltage can be generated for the magnetron, but thermal problems occur due to concentrated power losses in specific switching elements
Solution Approach 1:
The patent introduces dynamic operation by continuously alternating between two different switching modes. The controller dynamically switches between Mode 1 (activating S1/S2) and Mode 2 (activating S3/S4), ensuring that thermal stress is dynamically distributed across all switching elements. This dynamic approach prevents localized overheating and improves operational reliability.
3Use of energy by moving object
If alternating current is generated in the primary winding by conventional switching, then the magnetron can be powered, but considerable power losses occur in the switching elements
Solution Approach 1:
The patent employs periodic alternation between two switching modes to generate the alternating current in the primary winding. By switching between Mode 1 (S1/S2 activated) and Mode 2 (S3/S4 activated), the system maintains continuous AC generation for the magnetron while distributing energy losses across all four switching elements, thereby improving overall energy efficiency.
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 design effectively reduces thermal stress and power losses across switching elements, enhancing the operational efficiency and reliability of the microwave oven by alternating the switching patterns between different operating modes.
Implementation Method 1
a high-voltage generator (11) having a high-voltage transformer (14) and a full bridge (T3-T6)
Data Source
Figure 1~3
Figure 2
Figure 4~5
AI summary
The control circuit for a microwave oven has a full bridge (T3 - T6) for supplying a high-voltage transformer (14) with alternating current pulses. The control unit (13) of the device is designed to vary the sequence of control pulses for the switching elements of the full bridge (T3 - T6) in order to distribute the switching losses as evenly as possible across the different switching elements.