Induction Hob Oscillating Circuit Parameter Detection
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Solution Overview
Problem
Conventional induction hobs face limitations in accurately determining operating variables such as cooking vessel coverage, material, and temperature due to variations in impedance and resistance, leading to limited distinction between different materials and coverage levels.
Innovation Solution
A method involving a pulse-width modulated excitation voltage with varying voltage characteristics is used to determine oscillating circuit parameters, including impedance and inductance, by measuring current and voltage harmonics, allowing for improved detection of cooking vessel materials and coverage through a control unit that acts on the inverter and induction heating coil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional impedance measurement methods are used to determine cooking vessel coverage and material, then the device complexity remains low, but the measurement precision is insufficient to accurately distinguish between different materials and coverage levels
Solution Approach 1:
The patent applies periodic action by using pulse-width modulated excitation voltage with varying duty cycles performed n-times at different voltage characteristics. This periodic measurement approach allows multiple oscillating circuit parameters to be determined systematically, improving measurement precision for cooking vessel detection while maintaining a structured, manageable measurement sequence that controls complexity.
Solution Approach 2:
The patent implements parameter changes by varying the voltage characteristic (duty cycle) of the pulse-width modulated excitation voltage across multiple measurement cycles. By changing the voltage characteristic parameter n-times and determining voltage characteristic-dependent oscillating circuit parameters, the system achieves more precise material and coverage differentiation without requiring additional hardware complexity.
2Measurement precision
If multiple oscillating circuit parameters are determined through repeated measurements with different voltage characteristics, then the measurement precision for material distinction improves, but the loss of time increases due to n-times repetition of measurement cycles
Solution Approach 1:
The patent applies preliminary action by performing the n-times repeated measurements with different voltage characteristics during the initial phase before the cooking heating process begins. This allows all necessary oscillating circuit parameters to be determined in advance, enabling seamless transition to heating operation without significant power output interruption, thus minimizing the impact on overall cooking time.
Solution Approach 2:
The patent maintains continuity of useful action by ensuring that the measurement cycles are completed quickly and that the transition from measurement to heating operation is seamless. The system is designed to minimize power output interruption during the transition, ensuring that the cooking process can begin immediately after the n-times measurement cycle, thereby reducing the overall loss of time.
3Reliability
If voltage characteristic variations are applied to determine oscillating circuit parameters, then the reliability of cooking vessel detection improves, but the use of energy increases due to multiple excitation cycles
Solution Approach 1:
The patent applies partial action by using a limited number of voltage characteristic variations (n-times, where n is typically between 1 and 400) rather than continuous or excessive measurement cycles. This provides sufficient detection reliability for accurate cooking vessel identification while limiting the additional energy consumption to a manageable level, achieving an optimal balance between reliability and 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 method enhances the accuracy of cooking vessel detection by providing additional oscillating circuit parameters, enabling better distinction between different materials and coverage levels, while allowing for seamless transition to heating operation without significant power output interruption.
Implementation Method 1
an induction heating coil or inductor, which is assigned to a hob plate and is provided for the generation of an alternating magnetic field in the base of a pan which is to be heated
Implementation Method 2
The at least one capacitor and the induction heating coil are interconnected such that they constitute an oscillating circuit
Implementation Method 3
The at least one capacitor and the induction heating coil are interconnected such that they constitute an oscillating circuit, for example a parallel or series oscillating circuit
Data Source
AI summary
A method for operating an induction hob (100), wherein the induction hob (100) comprises: an inverter (1), which is supplied with a supply voltage (US), at least one capacitor (2, 3), and an induction heating coil (4), wherein the at least one capacitor (2, 3) and the induction heating coil (4) are interconnected such that they constitute an oscillating circuit (5), and wherein the inverter (1) is configured to generate a pulse-width modulated excitation voltage (UA) for the oscillating circuit (5) from the supply voltage (US), wherein the method comprises the following steps: a) generation of the pulse-width modulated excitation voltage (UA) having a predefined voltage characteristic, b) measurement of a resulting oscillating circuit current (iS), particularly by means of the induction heating coil (4), c) determination of electrical oscillating circuit parameters, according to the voltage characteristic of the pulse-width modulated excitation voltage (UA) and the measured oscillating circuit current (iS), d) n-times repetition of steps a) to c) using a different voltage characteristic of the excitation voltage (UA) for the determination of electrical voltage characteristic-dependent oscillating circuit parameters, and e) determination of operating variables of the induction hob (100) from voltage characteristic-dependent electrical oscillating circuit parameters.