Induction Cooker Power Switch Current Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing induction heating cookers face issues with high amplitude capacitor charge currents damaging the power switch, leading to a shorter lifespan, and require additional costly components for current detection, limiting maximum power and increasing circuit board costs.
Innovation Solution
A voltage change detection circuit using a DC-line capacitor as a current detector, comprising a voltage divider circuit and derivation circuit with standard resistance and capacitance elements, replaces high-cost current detection methods, allowing the control unit to monitor current through the power switch by detecting voltage changes on the DC-line capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current detection resistors are connected in series to the power switch for detecting current, then current detection is achieved, but additional components are needed which increases circuit board cost
Solution Approach 1:
The DC-line capacitor serves dual functions: filtering the rectified voltage and acting as a current detector. By monitoring the voltage changes across this existing capacitor, the system obtains current detection capability without adding separate detection components, thus reducing circuit board cost while maintaining measurement precision
Solution Approach 2:
The system uses its own existing components (DC-line capacitor) for current detection purposes. The voltage changes across the capacitor naturally provide current information, eliminating the need for external current detection resistors or transformers, thereby reducing overall system complexity and cost
2Power
If high amount of electric current is passed through the power switch to drive the induction coils, then maximum power is achieved, but the power switch is damaged and lifespan is shortened
Solution Approach 1:
The control unit continuously monitors voltage changes across the DC-line capacitor to detect peak currents in real-time. When peak current levels approach damaging thresholds, the control unit adjusts the switching duty cycle or frequency to limit current magnitude, thereby protecting the power switch while still allowing operation at high power levels within safe current limits
Solution Approach 2:
The system dynamically adjusts the power switch operating parameters (duty cycle, frequency) based on real-time current conditions detected through voltage monitoring. This dynamic control allows the system to operate at maximum power when conditions permit while automatically reducing current stress on the power switch when peak currents become excessive, extending component lifespan
3Measurement precision
If current detection resistors are used for detecting current on the power switch, then current monitoring is achieved, but additional components are needed which increases the cost of the circuit board
Solution Approach 1:
The DC-line capacitor is repurposed to serve as both a filtering component and a current sensing element. By measuring the voltage across this existing capacitor, the system achieves current monitoring functionality without requiring separate detection components, thereby simplifying manufacturing and reducing circuit board cost while maintaining accurate current measurement capability
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 solution effectively detects peak currents passing through the power switch without damaging it, reduces circuit board costs, and extends the induction heating cooker's lifespan by eliminating the need for expensive current detection components.
Implementation Method 1
a bridge rectifier that converts the alternative mains current to direct current
Implementation Method 2
a DC-line inductor and a DC-line capacitor disposed at the output of the bridge rectifier and which deliver DC voltage in a certain frequency range by filtering the voltage generated in the DC-line
Implementation Method 3
a DC-line inductor and a DC-line capacitor disposed at the output of the bridge rectifier and which deliver DC voltage in a certain frequency range by filtering the voltage generated in the DC-line
Implementation Method 4
providing the delivery of the energy stored in the resonant capacitor to the vessel by means of the induction coil
Implementation Method 5
The induction heating cooker functions according to the principle of heating a cast iron or steel ferromagnetic cooking container with the magnetic field effect generated by the induction coil
Implementation Method 6
the voltage change detection circuit comprises a voltage divider circuit which reduces the DC-line voltage to an easily-detectable level
Implementation Method 7
a derivation circuit which is connected in series to the voltage divider circuit and calculates the change of the voltage with respect to time (dv/dt)
Data Source
Figure 1
AI summary
The present invention relates to an induction heating cooker (1) comprising a bridge rectifier (3) that converts the alternative current to direct current, a DC-line inductor (4) and a DC-line capacitor (5) disposed at the output of the bridge rectifier (3), a parallel resonant circuit (8) having an induction coil (6) and a resonant capacitor (7) connected in parallel to the induction coil (6), a power switch (9) having an IGBT (Insulated Gate Bipolar Transistor) and a freewheel diode (D) connected in parallel to the IGBT, which changes to the conducting state in the closed position and provides the resonant capacitor (7) to be charged, providing the delivery of the energy stored in the resonant capacitor (7) to the vessel (K) by means of the induction coil (6) in the open position, and wherein the current passing through the power switch (9) can be detected in the open and closed positions of the power switch (9).