INDUCTION HEATING DEVICE, INDUCTION HEATING METHOD, AND PROGRAM

• US 20130248520A1
• Filed: 12/03/2010
• Published: 09/26/2013
• Est. Priority Date: 12/03/2010
• Status: Active Grant

• Current Assignee: Mitsui E&S Company Limited
• Original Assignee: Mitsui Engineering & Shipbuilding Company Limited (Mitsui E&S Holdings Co., Ltd.)
• Inventors: Uchida, Naoki, Okazaki, Yoshihiro, Ozaki, Kazuhiro
• Granted Patent: US 9,247,589 B2
• Time in Patent Office: Days
• US Class Current: 219/662
• CPC Class Codes: H05B 6/04 Sources of current
• CPC Class Codes: H05B 6/06 Control, e.g. of temperature, of power
• CPC Class Codes: H05B 6/062 for cooking plates or the like
• CPC Class Codes: H05B 6/08 using compensating or balancing arrangements
• CPC Class Codes: H05B 6/44 having more than one coil or coil segment

Abstract

The purpose of the present invention is to minimize switching losses of an inverter. An induction heating device includes: a plurality of induction heating coils (20) which are disposed adjacent with each other; a plurality of inverters (30), each of which has a capacitor (40) serially connected to each of the induction heating coils (20), and converts a DC voltage into a square wave voltage; and a control circuit (15) which controls so as to align the phase of coil currents flowing though the plurality of the induction heating coils (20), wherein the control circuit (15) controls the timing at which the square wave voltage transitions such that an instantaneous value of the square wave voltage is preserved in either the DC voltage or a turnover voltage, when the coil current zero crosses.

Claims

1. An induction heating device comprising:

a plurality of induction heating coils which are disposed adjacent with each other;

capacitors each of which is connected in series to each of the induction heating coils;

a plurality of inverters each of which applies a high frequency voltage converted from a DC voltage to each series circuit of the induction heating coil and the capacitor; and

a control circuit which performs pulse width control of the high frequency voltages, as well as controls the plurality of the inverters so as to align the phase of coil currents flowing through each of the plurality of the induction heating coils,

wherein each of the DC voltage is common for the plurality of the inverters.

2. The induction heating device, according to claim 1,

wherein the DC voltage can be lowered so that the maximum pulse width of all of the high frequency voltages converted by the plurality of the inverters becomes equal to or greater than a predetermined value.

3. The induction heating device, according to claim 1,

wherein the DC voltage is controlled such that a zero-cross timing at which the coil current flowing through the series circuit zero crosses from negative to positive is behind relative to a rising timing of the voltage applied to the series circuit.

4. The induction heating device, according to claim 1,

wherein the inverter comprises a transistor, and a diode in back-to-back connection, in each of the arms, and

the DC voltage is generated by a chopper circuit or a converter.

5. The induction heating device, according to claim 1,

further comprising an abnormal stop unit, which stops the inverter when the high frequency voltage rises after the coil current zero-crosses from negative to positive.

6. The induction heating device, according to claim 1,

wherein the plurality of the induction heating coils are disposed in proximity to a common heating element and

the control circuit variably controls the pulse width of a square wave voltage as the high frequency voltage so that electromagnetic energies supplied to the heating element by each of the induction heating coils are uniformed.

7. An induction heating method, performed by an induction heating device comprising:

a plurality of induction heating coils which are disposed adjacent with each other;

capacitors each of which is connected in series to each of the induction heating coils;

a plurality of inverters each of which applies a high frequency voltage converted from a DC voltage to each series circuit of the induction heating coil and the capacitor; and

a control circuit which performs pulse width control of the high frequency voltages,

wherein the control unit controls the plurality of the inverters, each having the common DC voltage, so as to align the phase of coil currents flowing through each of the plurality of the induction heating coils.

8. The induction heating method, according to claim 7,

wherein the DC voltage can be lowered so that the maximum pulse width of the high frequency voltages converted by the plurality of the inverters becomes equal to or greater than a predetermined value.

9. The induction heating method, according to claim 7,

wherein the DC voltage is controlled such that a zero-cross timing of a current flowing through the series circuit is behind relative to a rising timing of the voltage applied to the series circuit.

10. A program, with which a computer for the control circuit performs the induction heating method according to claim 7.