Induction Cooker Pot Detection With Split Capacitor Noise Control
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Solution Overview
Problem
Induction cookers generate noise during pot detection due to transient current changes, which existing technologies have not effectively mitigated.
Innovation Solution
The induction cooker employs a rectifying device, energy-storage devices with differing capacitances, and a control device to manage the switch and heating device, generating control signals to reduce transient current changes and noise by determining pot presence through output current changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pulse width modulation signal is used to drive the switch in the inverter circuit for pot detection, then the pot detection function is achieved, but a large amount of transient energy is generated causing the pot to vibrate and produce noise
Solution Approach 1:
The energy storage capacitor is divided into two separate capacitors: a first energy storage capacitor connected to the rectifying device and a second energy storage capacitor with greater capacitance connected to the switch device. This segmentation allows the system to use only the first capacitor during pot detection, limiting transient energy and reducing noise, while both capacitors work together during normal heating to provide sufficient power.
Solution Approach 2:
The control device is configured to control the switch device to be turned off before initiating pot detection. This preliminary action prepares the circuit by disconnecting the second energy storage capacitor from the heating device, ensuring that only limited energy from the first capacitor is available during detection, thereby preventing excessive transient energy and noise generation.
2Power
If the switch device is turned on to provide sufficient energy for heating, then the heating performance is improved, but transient current changes increase causing noise during pot detection
Solution Approach 1:
The energy storage system is segmented into two capacitors with different capacitances. The second capacitor has greater capacitance to provide sufficient energy for heating when both are connected, while the first capacitor alone provides limited energy during detection to reduce transient current changes and noise.
Solution Approach 2:
The system dynamically switches between different energy storage configurations: during pot detection, only the first energy storage capacitor is connected to limit transient energy; during normal heating operation, both capacitors are connected to provide full heating power. This dynamic reconfiguration optimizes performance for each operational phase.
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 reduces transient current changes and associated noise during pot detection, enhancing the operational quietness of induction cookers.
Implementation Method 1
a rectifying device, a first energy-storage device, a switch device, a second energy-storage device, a first heating device and a control device. The rectifying device is configured to receive an alternating-current voltage and to convert the alternating-current voltage into a direct-current voltage
Implementation Method 2
The first energy-storage device is coupled to the rectifying device and configured to receive the direct-current voltage and to store energy
Implementation Method 3
For the principle of detecting the pot, a pulse width modulation (PWM) signal with a fixed frequency is used to drive a switch (such as an insulated gate bipolar transistor (IGBT)) in an inverter circuit. At the same time, a current may flow through the coil inside the inverter
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
An induction cooker includes a rectifying device, a first energy-storage device, a switch device, a second energy-storage device, a heating device and a control device. The capacitance of the second energy-storage device is greater than the capacitance of the first energy-storage device. When the induction cooker is just starting, the control device controls the switch device to be turned off, such that the heating device generates an output current according to an energy of the first energy-storage device. The control device determines whether a pot is on the heating device according to a change state of the output current. When the pot is on the heating device, the control device controls the switch device to be turned on, such that the first and second energy-storage devices are coupled, and the heating device heats the pot according to energies of the first and second energy-storage devices.