Induction Cooking Areas with Phase-Shifted Control for EMC Noise Reduction
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Solution Overview
Problem
Existing induction devices experience interference issues such as noise, flicker, and non-compliance with EMC standards due to intermodulation and ripple currents, which affect user comfort and compliance with legal guidelines.
Innovation Solution
The induction device employs a control unit that operates multiple induction targets with alternating current frequencies and phase shifts in controlled intervals to minimize interference, using phase angles calculated based on the number of targets and frequencies to ensure quiet operation and compliance with EMC standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple induction targets are operated simultaneously with the same frequency, then productivity is improved, but noise and interference increase due to intermodulation
Solution Approach 1:
The control unit divides the control period into multiple control intervals and operates different induction targets in different intervals with different phase shifts. This periodic switching pattern allows multiple targets to be operated simultaneously while minimizing intermodulation noise by ensuring that not all targets operate at the same frequency at the same time.
Solution Approach 2:
The control unit changes the operating parameters (frequency and phase shift) of the induction targets dynamically across different control intervals. By varying these parameters, the system can operate multiple targets simultaneously while controlling the intermodulation effects that cause noise and interference.
2Productivity
If induction targets are operated with high power, then productivity is improved, but harmful ripple currents increase affecting EMC compliance
Solution Approach 1:
The control unit employs periodic control intervals where induction targets are switched on and off in a structured pattern. This periodic operation allows high power delivery during active intervals while creating controlled ripple current patterns that can be managed to meet EMC compliance requirements.
Solution Approach 2:
The control period is segmented into multiple control intervals, and the operation of induction targets is segmented across these intervals with different phase shifts. This segmentation distributes the ripple current generation over time and frequency, making it easier to control and comply with EMC standards while maintaining high overall power output.
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 approach reduces noise and interference, enhancing user comfort and compliance with legal guidelines by minimizing intermodulation and ripple currents, allowing for efficient and safe operation.
Implementation Method 1
an induction device (10a, 10b, 10c) with a plurality of independently controllable induction targets (12a-18a, 12b-18b, 12c-18c) and with at least one control unit (20a, 20b, 20c) which is provided to repeatedly control the induction targets (12a-18a, 12b-18b, 12c-18c) with at least one alternating current frequency (24a, 24b, 24c) and to supply it with energy
Implementation Method 2
In the first control interval (26a, 26b, 26c), the control unit (20a, 20b, 20c) operates at least two of the induction targets (12a-18a, 12b-18b, 12c-18c) with a first phase shift (32a, 32b, 32c) in order to thus minimize interference
Data Source
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AI summary
The invention relates to an induction device (10a; 10b; 10c), in particular an induction cooking device, comprising a plurality of independently controllable induction areas (12a, 14a, 16a, 18a; 12b, 14b, 16b, 18b; 12c, 14c, 16c, 18c) and comprising at least one control unit (20a; 20b) which is provided to repetitively control the induction areas (12a, 14a, 16a, 18a; 12b, 14b, 16b, 18b; 12c, 14c, 16c, 18c) within a control period (22a; 22b) formed by a first control interval (26a; 26b) and at least one second control interval (28a; 28b) with at least one AC frequency (24a; 24b) and to supply same with energy. In order to provide a generic device with improved characteristics in terms of safe and/or comfortable operation, in the first control interval (26a; 26b), the control unit (20a; 20b) operates at least two of the induction areas (12a, 14a, 16a, 18a; 12b, 14b, 16b, 18b; 12c, 14c, 16c, 18c) with a first phase shift (32a; 32b) in order to minimise interferences.