Power control apparatus and method for electric cookers

• US 20070012684A1
• Filed: 08/10/2005
• Published: 01/18/2007
• Est. Priority Date: 07/12/2005
• Status: Active Grant

• Current Assignee: Holtek Semiconductor Incorporated
• Original Assignee: Holtek Semiconductor Incorporated
• Inventors: Chen, Chun-Hsiung, Lin, Chun-Ku, Liu, Yuan-Ho
• Granted Patent: US 7,271,372 B2
• Time in Patent Office: Days
• US Class Current: 219/620
• CPC Class Codes: H05B 2213/07 Heating plates with temperature control means
• CPC Class Codes: H05B 6/062 for cooking plates or the like

Abstract

A power control apparatus for electric cookers is disclosed, which comprises: an input unit, for setting parameters of temperature control, power control and timing control, etc.; an output unit, for displaying parameters of temperature, power and timing, etc.; a micro controller unit (MCU), having a programmer pulse generator (PPG) and at least an analog/digital converter built therein, being used for processing the inputs of the input unit and controlling the outputs to the output unit while detecting signals of synchronization, oscillation, over-voltage (OV), and over-current (OC); a power circuit, for providing power to the power control apparatus; an exciter-coil circuit, for adjusting the power of the power control apparatus; an output circuit of insulated gate bipolar transistor (IGBT), for driving the exciter-coil circuit; a drive circuit of insulated gate bipolar transistor (IGBT), being used as voltage transformation interface between the MCU and the output circuit of insulated gate bipolar transistor (IGBT) while being used for driving the output circuit of insulated gate bipolar transistor (IGBT), wherein a command can be inputted externally to the MCU for restarting or stopping the output of the PPG; and the PPG is capable of outputting pulses of programmable pulse width, being programmed by a software in view of power control and the protection of power control apparatus.

Claims

1. A power control apparatus for a electric cooker, comprising:

an input unit, for setting parameters of temperature control, power control and timing control;

an output unit, for displaying parameters of temperature, power and timing;

a micro controller unit (MCU), being used for processing the inputs of the input unit and controlling the outputs to the output unit while detecting signals of synchronization (SYN), oscillation (OS), over-voltage (OV), and over-current (OC);

a power circuit, for providing power to the power control apparatus;

an exciter-coil circuit, for adjusting the power of the power control apparatus;

an output circuit of insulated gate bipolar transistor, for driving the exciter-coil circuit; and

a drive circuit of insulated gate bipolar transistor (IGBT), being used as voltage transformation interface between the MCU and the output circuit of insulated gate bipolar transistor (IGBT) while being used for driving the output circuit of insulated gate bipolar transistor (IGBT).

2. The power control apparatus of claim 1, wherein the input unit further comprises a keyboard and a temperature sensor.

3. The power control apparatus of claim 1, wherein the output unit further comprises a fan, a buzzer and a display.

4. The power control apparatus of claim 1, wherein the micro controller unit further comprises a power detection circuit.

5. The power control apparatus of claim 1, wherein the micro controller unit further comprises:

at least an analog/digital converter;

a programmable pulse generator (PPG), comprising at least a comparator, a timer, a prescaler, and a control element; and

a processing core, for controlling the control unit of the programmable pulse generator.

6. The power control apparatus of claim 1, wherein the electric cooker is a electro-magnetic oven.

7. The power control apparatus of claim 1, wherein the electric cooker is an electric rice cooker.

8. A power control method for electric cooker, adapted for controlling the processes of a MCU built in a power control apparatus, which comprises the step of:

(1) using a second comparator as a signal source for providing signals to control the restart and output of a programmable pulse generator (PPG) arranged in a MCU, while using a timer and a prescaler for timing and controlling a specific output time of the PPG, wherein the setting of the timer and the prescaler is programmed by a software, and the output of the PPG is stopped as soon as the timing of the specific output time is up;

(2) using a first comparator to provide a signal for stopping the output of the PPG;

(3) controlling the output time of the PPG by using timer cooperating with the prescaler; and

(4) using a control element for disabling/enabling the first and second comparators, and for setting up the timer and the prescaler, and for restarting a disable/enable control, and for stopping the disable/enable control, and for controlling the output of the PPG with respect to the software, and for detecting the status of the PPG.

9. The method of claim 8, wherein the programmable pulse generator (PPG) arranged in the micro controller unit is controlled by a means comprising the steps of:

(a) stopping the output of the PPG while a falling edge being generated at an output (C0OUT) of the first comparator and a P0SPEN bit being enabled, i.e. when an instantaneous current passing an insulated gate bipolar transistor (IGBT) is larger than a specific value by a predetermined amount, an response is generated on the OC terminal of a current transformer (CT) which is connected to the C0VIN−

terminal of the MCU, being the negative of the first comparator, and voltage generated according to the response is larger than a reference voltage of the C0VIN+terminal of the MCU, being the positive of the first comparator, the falling edge is occurring at the output (i.e. C0OUT) of the first comparator for enabling the stop of the PPG; and

similarly, when a temperature is too high to cause the corresponding voltage at he C0VIN−

terminal to be higher than the reference voltage of the C0VIN+terminal, the output of the PPG is stopped;

(b) restarting the output of the PPG while a falling edge being generated at an output (C1OUT) of the second comparator and a P1SPEN bit being enabled, i.e. when the voltage of an terminal of a exciter-coil circuit, which is being connected the insulated gate bipolar transistor (IGBT), is dropped from a high potential to zero potential, the PPG is restarted, i.e. when the voltage representing a synchronous signal SYN-I is lower than that of another synchronous signal SYN-P, a falling edge is generated at the output (i.e. C1OUT) of the second comparator for enabling the restart of the PPG;

(c) enabling the restarting and the stopping of the PPG by using a software to detect/program the status of a POST bit;

(d) employing the PPG as a timer while using a software to set up the timer and a prescaler, both for timing and controlling a specific output time of the PPG, which is referred as the pulse width of the PPG, and thus achieving an object of power control;

(e) detecting and controlling signals of synchronization (SYN), oscillation (OS), over-voltage (OV), and over-current (OC) with respect to the process of step (a) to step (d).