Induction heating cooker and control circuit therefor

An induction heating cooker, comprising:

• an inductive coil having a first terminal coupled to a power voltage;
• a switch element having a first terminal coupled to a second terminal of the inductive coil, and a second terminal coupled to a common voltage;
• and
• a control circuit, comprising:
• a first comparator having a first input terminal coupled to the first terminal of the inductive coil, a second input terminal coupled to the second terminal of the inductive coil, and an output terminal for outputting a trigger signal;
• a second comparator having a first input terminal coupled to a first reference voltage, a second input terminal coupled to the first terminal of the switch element, and an output terminal for outputting a fading signal, which is enabled when a voltage of the second input terminal is higher than the first reference voltage;
• a pulse generator having an output terminal coupled to a control terminal of the switch element, wherein the output terminal of the pulse generator outputs a pulse to control the switch element when the trigger signal is changed from a second logic level to a first logic level, and the pulse generator reduces a pulse width of the pulse when the fading signal is enabled;
• a bridge rectifier comprising a first terminal, a second terminal, a third terminal and a fourth terminal, wherein the first terminal and the second terminal of the bridge rectifier are coupled to an AC voltage source, the third terminal of the bridge rectifier outputs the power voltage, and the fourth terminal of the bridge rectifier outputs the common voltage;
• and
• a third comparator having a first input terminal coupled to a second reference voltage, a second input terminal selectively coupled to the first terminal or the second terminal of the bridge rectifier, and an output terminal for outputting a stop signal, wherein:
• the stop signal is enabled when a voltage of the second input terminal is higher than the first reference voltage;
• the pulse generator is coupled to the output terminal of the third comparator and receives the stop signal;
• and
• the pulse generator stops outputting the pulse when the stop signal is enabled.

A control circuit for controlling an induction heating cooker, wherein the induction heating cooker comprises an inductive coil, a bridge rectifier and a switch element, the inductive coil is coupled between a power voltage and a first terminal of the switch element, a second terminal of the switch element is coupled to a common voltage, the bridge rectifier comprises a first terminal, a second terminal, a third terminal and a fourth terminal, the first terminal and the second terminal of the bridge rectifier are coupled to an AC voltage source, the third terminal of the bridge rectifier outputs the power voltage, and the fourth terminal of the bridge rectifier outputs the common voltage, the control circuit comprising:

• a first comparator having a first input terminal coupled to a first terminal of the inductive coil, a second input terminal coupled to a second terminal of the inductive coil, and an output terminal for outputting a trigger signal;
• a third comparator having a first input terminal coupled to a second reference voltage, a second input terminal selectively coupled to the first terminal or the second terminal of the bridge rectifier, and an output terminal for outputting a stop signal, which is enabled when a voltage of the second input terminal is higher than a first reference voltage;
• a pulse generator, which is coupled to the first comparator and the output terminal of the third comparator, receives the stop signal and the trigger signal, outputs a pulse to control the switch element when the trigger signal is changed from a second logic level to a first logic level, and stops outputting the pulse when the stop signal is enabled.

A control circuit for controlling an induction heating cooker, which comprises an inductive coil and a switch element, wherein the inductive coil is coupled between a power voltage and a first terminal of the switch element, and a second terminal of the switch element is coupled to a common voltage, the control circuit comprising:

• a first comparator having a first input terminal coupled to a first terminal of the inductive coil, a second input terminal coupled to a second terminal of the inductive coil, and an output terminal for outputting a trigger signal;
• a second comparator having a first input terminal coupled to a first reference voltage, a second input terminal coupled to the first terminal of the switch element, and an output terminal for outputting a fading signal, which is enabled when a voltage of the second input terminal is higher than the first reference voltage;
• a pulse generator for outputting a pulse to control the switch element when the trigger signal is changed from a second logic level to a first logic level, and for reducing a pulse width of the pulse when the fading signal is enabled;
• a first register for storing duty cycle data;
• and
• a second register for storing difference data,
• wherein the pulse generator determines a duty cycle of the pulse according to the duty cycle data, and the pulse generator determines the duty cycle of the pulse by subtracting the difference data from the duty cycle data when the fading signal is enabled.

An induction heating cooker, comprising:

• an inductive coil having a first terminal coupled to a power voltage;
• a switch element having a first terminal coupled to a second terminal of the inductive coil, and a second terminal coupled to a common voltage;
• and
• a control circuit, comprising:
• a first comparator having a first input terminal coupled to the first terminal of the inductive coil, a second input terminal coupled to the second terminal of the inductive coil, and an output terminal for outputting a trigger signal;
• a second comparator having a first input terminal coupled to a first reference voltage, a second input terminal coupled to the first terminal of the switch element, and an output terminal for outputting a fading signal, which is enabled when a voltage of the second input terminal is higher than the first reference voltage;
• a pulse generator having an output terminal coupled to a control terminal of the switch element, wherein the output terminal of the pulse generator outputs a pulse to control the switch element when the trigger signal is changed from a second logic level to a first logic level, and the pulse generator reduces a pulse width of the pulse when the fading signal is enabled;
• a first register for storing duty cycle data;
• and
• a second register for storing difference data,
• wherein the pulse generator determines a duty cycle of the pulse according to the duty cycle data, and the pulse generator determines the duty cycle of the pulse by subtracting the difference data from the duty cycle data when the fading signal is enabled.

A control circuit for controlling an induction heating cooker, wherein the induction heating cooker comprises an inductive coil, a bridge rectifier and a switch element, the inductive coil is coupled between a power voltage and a first terminal of the switch element, a second terminal of the switch element is coupled to a common voltage, the bridge rectifier comprises a first terminal, a second terminal, a third terminal and a fourth terminal, the first terminal and the second terminal of the bridge rectifier are coupled to an AC voltage source, the third terminal of the bridge rectifier outputs the power voltage, and the fourth terminal of the bridge rectifier outputs the common voltage, the control circuit comprising:

• a first comparator having a first input terminal coupled to a first terminal of the inductive coil, a second input terminal coupled to a second terminal of the inductive coil, and an output terminal for outputting a trigger signal;
• a third comparator having a first input terminal coupled to a second reference voltage, a second input terminal selectively coupled to the first terminal or the second terminal of the bridge rectifier, and an output terminal for outputting a stop signal, which is enabled when a voltage of the second input terminal is higher than a first reference voltage;
• a pulse generator, which is coupled to the first comparator and the output terminal of the third comparator, receives the stop signal and the trigger signal, outputs a pulse to control the switch element when the trigger signal is changed from a second logic level to a first logic level, and stops outputting the pulse when the stop signal is enabled;
• a first register for storing duty cycle data;
• and
• a second register for storing difference data,
• wherein the pulse generator determines a duty cycle of the pulse according to the duty cycle data, and the pulse generator determines the duty cycle of the pulse by subtracting the difference data from the duty cycle data when the fading signal is enabled.