Induction Heating Gate Driver Negative Voltage Protection Circuit
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Solution Overview
Problem
Induction heating devices face challenges in accurately detecting vessels on the working coil due to degraded accuracy and high power consumption, especially when input voltage changes, and they often suffer from damage due to negative voltage applied to gate drivers during switching operations.
Innovation Solution
The induction heating device incorporates a protection circuit with resistors, diodes, and a bootstrap circuit to minimize negative voltage exposure to the gate driver, allowing for real-time control of switching elements and improved vessel detection accuracy without the need for insulated gate drivers or separate insulating elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the gate driver is directly connected to the inverter for real-time switching control, then the switching control speed and responsiveness are improved, but negative voltage during switching damages the gate driver
Solution Approach 1:
An isolated gate driver is introduced as an intermediary component between the controller and the inverter circuit. The isolated gate driver includes a first isolated gate driver for driving the first switching element and a second isolated gate driver for driving the second switching element. This intermediary component provides galvanic isolation, allowing real-time switching control signals to be transmitted while blocking harmful negative voltage transients from reaching the control circuitry, thus resolving the contradiction between fast switching response and component reliability.
2Reliability
If a pulse transformer is used to insulate the gate driver output terminal from the inverter, then negative voltage damage is prevented, but real-time switching control capability is lost
Solution Approach 1:
The patent employs an isolated gate driver as an advanced intermediary solution that overcomes the limitations of traditional pulse transformers. This isolated gate driver maintains galvanic isolation to protect against negative voltage while incorporating active circuitry that can generate precise, high-speed switching signals. The isolation barrier allows digital control signals to be converted into appropriate gate drive waveforms with fast rise and fall times, enabling real-time switching control without the bandwidth limitations of transformer-based isolation.
3Use of energy by moving object
If vessel detection is performed only at zero voltage time points, then power consumption is reduced, but detection accuracy degrades and cannot adapt to changing input voltage conditions
Solution Approach 1:
The patent implements a dual-mode vessel detection strategy that combines periodic zero-voltage-point detection with continuous monitoring capabilities. The controller is configured to detect vessel presence by monitoring voltage characteristics at zero-crossing points during normal operation, which consumes minimal power. However, when input voltage changes are detected or when the system enters specific operational modes, the controller can transition to more frequent or continuous detection, ensuring accurate vessel detection across varying voltage conditions while maintaining energy efficiency during stable operation.
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 enhances vessel detection accuracy, reduces power consumption, and prevents overcurrent noise, while lowering development costs and simplifying design by enabling real-time switching control and negative voltage protection.
Implementation Method 1
a protection circuit diode Dpt between a ground G and a second node N2 between the protection circuit resistance Rpt and the reference voltage terminal Vs
Implementation Method 2
a bootstrap capacitor Cboot connected to the second node N2, a bootstrap diode Dboot and a bootstrap resistor Rboot provided between the bootstrap capacitor Cboot and the external power supply 250
Implementation Method 3
In the induction heating method, eddy current may be generated in the object (for example, the cooking vessel) made of metal based on a magnetic field that is generated around the coil when a high-frequency power of a predetermined magnitude is applied to the coil to heat the object
Implementation Method 4
the switching unit 62 may provide the working coil 63 with resonant current through switching
Data Source
AI summary
An induction heating device includes a working coil, an inverter including a first switching element and a second switching element; a gate driver including a first sub-gate driver and a second sub-gate driver; and a protection circuit disposed between the inverter and the gate driver. The protection circuit includes a first resistor disposed between a gate terminal of the first switching element and an output terminal of the first sub-gate driver, a second resistor connected electrically in parallel to the first resistor, a protection circuit resistor disposed between a reference voltage terminal of the first sub-gate driver and a first node between the first switching element and the second switching element, a protection circuit diode disposed between a ground and a second node between the protection circuit resistance and the reference voltage terminal, and a bootstrap circuit disposed between the second node and the external power supply.