Induction Hob Inverter Grounding for Charge Accumulation
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Solution Overview
Problem
Induction hobs face uncontrolled charge accumulation in the bus line due to induced currents in inactive inductors, leading to potential damage to electronic components, especially in matrix induction cooktops with multiple power electronics assemblies.
Innovation Solution
A control unit grounds an inductor when it is deactivated, particularly when an adjacent inductor is active, using a semiconductor switch like an IGBT transistor to prevent charge accumulation and uncontrolled discharges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the inductor is left floating after deactivation, then the circuit complexity is reduced, but charge accumulation occurs in the bus line leading to uncontrolled discharges
Solution Approach 1:
The control unit actively grounds the inductor immediately upon deactivation, preventing charge accumulation before it can cause damage. This preliminary grounding action eliminates the need for complex active discharge circuits while protecting electronic components from uncontrolled discharges.
2Reliability
If a separate switching element is added to ground the inductor, then charge accumulation is prevented, but the device complexity increases
Solution Approach 1:
The control unit reuses the existing inverter switching elements to ground the inductor during deactivation. This multi-functional use of existing components prevents charge accumulation without adding separate dedicated grounding switching elements, thus maintaining circuit simplicity while ensuring reliability.
3Reliability
If the switching element is closed continuously, then charge accumulation is prevented, but power consumption increases
Solution Approach 1:
The control unit closes the switching element only during the deactivation phase of the inductor, creating a periodic grounding action rather than continuous closure. This timing-based control prevents charge accumulation when needed while minimizing power consumption by keeping the switching element open during active phases.
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 effectively prevents charge accumulation in the bus line, reducing the risk of damage to electronic components and increasing the service life of the induction hob by ensuring controlled discharges.
Implementation Method 1
If, for example, an alternating magnetic field is induced in an inactive inductor by the operation of a neighboring inductor, a current is induced which can flow through the freewheeling diode into the bus line of the inverter connected to the positive pole of the rectifier
Data Source
Figure 1
Figure 2~3
Figure 4a~5
AI summary
The cooker has a control unit for activating and deactivating inductors (10a, 10b), and a switching element (68) for earthing one of the inductors. The control unit closes the switching element, and earths the inductors when the inductors are deactivated. The switching element is designed as a semiconductor switch having inverters (32a) that are connected with the inductors. The inductors are identically constructed and arranged on a two-dimensional grid. The switching element includes a transistor (64) and a diode (60) that is arranged parallel to the transistor. An independent claim is also included for a method for operating an induction cooker.