JPH09245954A - Induction heating cooking apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the circuit of an induction heating cooking apparatus by keeping on a switching element for a certain period immediately before the start of an inverter, and charging the drive control power supply for another switching element. SOLUTION: Receiving an inverter start signal, a charge signal output means 11 actuates the second switching means 2b located on the low potential side of a DC power supply 1 through the second driving means 4. With turn-on of the switching means 2b, the driving power supply 8 for the first driving means 3 is charged through a charging means 9 from the driving power supply 7 for the second driving means 4. When a sufficient charge is made after a certain time, the charge signal output means 11 sends a start signal to a signal transmitting means 5 and a driving time setting means 6. This means 6 divides the signal transmitting period from the transmitting means 5 and drives the first and second switching means 2a, 2b alternately through the driving means 3, 4. An inverter circuit 2 turns the DC power supply 1 into a high-frequency current.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating cooker characterized by a method of driving an inverter circuit having two switching means.

[0002]

2. Description of the Related Art In recent years, as household power supplies have been increased to 200 V, demand for high-output 200 V induction heating cookers is increasing. In the 200 V induction heating cooker, it is common to use an inverter circuit having two switching means because of the problem of withstand voltage of the switching means. Hereinafter, the configuration will be described with reference to FIG.

As shown in FIG. 3, a first switching means 2a connected to a DC power source 1 (IGB in this conventional example).
T) and the second switching means 2b (IG in the conventional example).
BT) or the like, an inverter circuit 2, a first driving means 3 for driving the first switching means 2a, a second driving means 4 for driving the second switching means 2b, an oscillating means 5, A drive time setting means 6 for setting the drive time of the first switching means 2a and the second switching means 2b by dividing the oscillation cycle set by the oscillation means 5;
The charging means 9 for charging the driving power source 7 of the driving means 4 and the driving power source 8 of the first driving means 3 while driving the second switching means 2b And a low voltage protection means 10 which stops the operation of the first driving means 3 when the voltage of the driving power source 8 of the first driving means 3 is equal to or lower than a predetermined voltage.

To explain the operation in the above configuration, when a signal for activating the inverter circuit 2 is transmitted to the oscillating means 5 and the drive time setting means 6, the oscillating circuit 5 oscillates at a predetermined oscillation cycle to set the drive time. The means 6 divides the oscillation period to divide the oscillation period into first and second switching means 2a,
2b is set, and the first and second driving means 3 and 4 are set to the first and second switching means 2a and 2b.
Are alternately driven, the inverter circuit 2 converts the DC power supply 1 into a high-frequency current to heat a load such as a pot.
At the time of start-up, the driving power source 8 of the first driving means 3 is 0 V, so that the first driving means 3 causes the first switching means 2 to operate.
Even if it tries to drive a, it cannot be driven. Therefore, first, the second switching means 2b is driven into a short circuit state, and the emitter of the first switching means 2a and the second switching means 2b
The emitter of the switching means 2b becomes the same potential. At this time, from the driving power source 7 of the second driving means 4 to the charging means 9
The charging of the driving power source 8 of the first driving means 3 is started via the.

Since the IGBTs used in the first and second switching means 2a and 2b may be destroyed when driven at a low voltage, the voltage of the driving power source 8 of the first driving means 3 is set to a predetermined value. Low voltage protection means 1 until the voltage exceeds
When 0, the operation of the first drive means 3 is stopped.

[0006]

However, the above-mentioned conventional structure has a problem that the circuit cost becomes high because the low voltage protection means is required.

[0007]

In order to solve the above problems, the present invention provides a first switching means connected to the high potential side of a DC power supply and a second switching means connected to the low potential side of the DC power supply. An inverter circuit having switching means,
An oscillating unit, a drive time setting unit that divides an oscillating cycle set by the oscillating unit and sets a drive time of the first switching unit and the second switching unit, and drives the first switching unit. A first drive means,
Second driving means for driving the second switching means, and charging means for charging a driving power supply of the first driving means while driving the second switching means,
Immediately before starting the inverter circuit, a charging signal output means for outputting a signal for driving the second switching means is always provided for a predetermined time or more.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 is such that charging means for charging the driving power source of the first driving means while driving the second switching means, and always just before the activation of the inverter circuit. By providing the charging signal output means for outputting the signal for driving the second switching means for a predetermined time or longer, it is possible to charge the driving power source of the first driving means before starting the inverter circuit. Is.

According to a second aspect of the present invention, charging means for charging the driving power source of the first driving means while driving the second switching means, and at least a predetermined time after activation of the inverter circuit. Since the signal stopping means for outputting the signal for stopping the driving of the first switching means is provided, only the second driving means always operates for a predetermined time or more after the start of the inverter circuit so that the first driving means is driven. The one that can charge the power supply.

[0010]

【Example】

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, the first switching means 2a (in this embodiment, I
(GBT) and the second switching means 2b (IGBT in the present embodiment) and the like, the first driving means 3 for driving the first switching means 2a, the second
Drive means 4 for driving the switching means 2b of
And an oscillating means 5 and a drive time setting means 6 for dividing the oscillating cycle set by the oscillating means 5 to set the drive time of the first switching means 2a and the second switching means 2b
And a charging means 9 for charging the driving power source 7 of the second driving means 4 and the driving power source 8 of the first driving means 3 while driving the second switching means 2b (in the present embodiment, A serial body of a resistor and a diode), and a charge signal output means 11 that always outputs a signal for driving the second switching means 2b for a predetermined time immediately before starting the inverter circuit 2.

To explain the operation in the above configuration, when the signal for activating the inverter circuit 2 is transmitted to the charging signal output means 11, the signal is output from the charging signal output means 11 to the second driving means 4 and the second driving means 4 is output. Driving means 4 drives the second switching means 2b. When the second switching means 2b is driven to be in a short-circuit state, the emitter of the first switching means 2a and the emitter of the second switching means 2b have the same potential, and the second driving means 4
The driving power supply 7 is charged to the driving power supply 8 of the first driving means 3 via the charging means 9. Then, after a lapse of a predetermined time after sufficient charging, the charging signal output means 11 is set to the second
The signal output to the driving means is stopped, and the starting signal of the inverter circuit 2 is output to the oscillating means 5 and the driving time setting means 6. After the activation signal is input, the oscillation circuit 5 starts oscillation at a predetermined oscillation cycle and outputs it to the drive time setting means 6. The drive time setting means 6 divides the oscillation cycle input from the oscillation circuit 5 to determine the drive time of the first switching means 2a and the second switching means 2b, and the first drive means 3 and the second drive means. Alternately output to the means 4. At this time, since the driving power source 8 of the first driving means 3 has already been charged, as soon as the signal from the driving time setting means 6 is output to the first driving means 3, the first switching means 2a is supplied with a sufficient voltage. Can be safely driven by. By alternately driving the first switching means 2a and the second switching means 2b, the inverter circuit 2 converts the DC power supply 1 into a high-frequency current to heat a load such as a pot.

As described above, according to this embodiment, the charging means 9 for charging the driving power source 8 of the first driving means 3 and the activation of the inverter circuit 2 while driving the second switching means 2b. A charge signal output means 11 that always outputs a signal for driving the second switching means 2b just before a predetermined time.
By including the above, the driving power source 8 of the first driving unit 3 can be charged before the inverter circuit 2 is started. If the charging signal output means 11 is composed of a microcomputer, it can be realized with almost no increase in cost.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to FIG. As shown in FIG. 2, the first switching means 2a (IGBT in this embodiment) and the second switching means 2b connected to the DC power supply 1 are connected.
Inverter circuit 2 including (IGBT in this embodiment) and the like
A first driving means 3 for driving the first switching means 2a and a second driving means 3 for driving the second switching means 2b.
The driving means 4, the oscillating means 5, and the oscillating cycle set by the oscillating means 5 are divided into the first switching means 2a and the second switching means 2a.
Drive time setting means 6 for setting the drive time of the switching means 2b, the drive power source 7 for the second drive means 4, and the first drive means 3 for the first drive means 3 while the second switching means 2b is being driven. The charging means 9 (in this embodiment, a series body of a resistor and a diode) for charging the driving power source 8 and the first switching means 2a are always kept for a predetermined time after the start of the inverter circuit 2.
And a signal stopping means 12 for outputting a signal for stopping the driving.

To explain the operation in the above configuration, when a signal for activating the inverter circuit 2 is transmitted to the oscillating means 5, the drive time setting means 6 and the signal stopping means 12, the oscillating circuit 5 oscillates at a predetermined oscillation cycle. Is output to the drive time setting means 6, and the drive time setting means 6 divides the oscillation cycle input from the oscillation circuit 5 to determine the drive time of the first switching means 2a and the second switching means 2b. , And alternately output to the first drive means 3 and the second drive means 4. In the signal stopping means 12, the driving time setting means 6 outputs the first switching means to the first driving means 3 for a predetermined time in which the driving power source 8 of the first driving means 3 is sufficiently charged. Stop the signal driving 2a. Therefore, during this predetermined time, the drive time setting means 6
Is transmitted to only the second driving means 4, and only the second switching means 2b is driven. When the second switching means 2b is driven into a short circuit state, the emitter of the first switching means 2a and the emitter of the second switching means 2b have the same potential, and the driving power source 7 for the second driving means 4 is generated. The charging power source 8 charges the driving power source 8 of the first driving means 3 from the charging means 9. Then, after a predetermined time after sufficient charging, the signal from the drive time setting means 6 which has been stopped by the signal stop means 12 to the first drive means 3 is released, whereby the first drive means 3 is released.
Also, the operation is started and the first switching means 2a is safely driven with a sufficient voltage. By alternately driving the first switching means 2a and the second switching means 2b,
The inverter circuit 2 converts the DC power supply 1 into a high frequency current to heat a load such as a pan.

As described above, according to this embodiment, the charging means 9 for charging the driving power source 8 of the first driving means 3 and the activation of the inverter circuit 2 while driving the second switching means 2b. Always after a predetermined time, the first switching means 2
By including the signal stopping means 12 for outputting the signal for stopping the driving of a, it is possible to drive only the second switching means 2b for a predetermined time after starting the inverter circuit 2, and the first driving means 3 The driving power source 8 can be charged. If the signal stopping means 12 is composed of a microcomputer, it can be realized with almost no increase in cost.

In the first and second embodiments, the emitter of the first switching means 2a and the collector of the second switching means 2b are connected, but the first switching means 2a and the second switching means 2b are connected. Even if the diode is connected between them, the same structure is obtained as long as it has a charging means 9 for charging the driving power source 8 of the first driving means 3 while driving the second switching means 2b. It goes without saying that the effect can be obtained.

[0017]

As described above, according to the first aspect of the invention, the first switching device is driven while the second switching device is being driven.
By providing the charging means for charging the driving power source of the driving means and the charging signal output means for always outputting the signal for driving the second switching means for a predetermined time or more immediately before the start of the inverter circuit, the inverter circuit First before launching
The driving power source of the driving means can be charged, and the driving of the first switching means can be safely started.

According to the second aspect of the invention,
The charging means for charging the driving power source of the first driving means while driving the switching means and the signal for always stopping the driving of the first switching means for a predetermined time or longer after the inverter circuit is activated. Since the signal stopping means is provided, the second circuit is always operated for a predetermined time or longer after the inverter circuit is started.
Only the driving means of (1) operates to charge the driving power source of the first driving means, and the driving of the first switching means can be safely started.

Further, in the case of an induction heating cooker having a microcomputer, if the microcomputer is caused to execute the charging signal output means according to claim 1 and the signal stopping means according to claim 2, it can be realized with almost no increase in cost. be able to.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of an induction heating cooker according to a first embodiment of the present invention.

FIG. 2 is a circuit block diagram of an induction heating cooker according to a second embodiment of the present invention.

FIG. 3 is a circuit block diagram of a conventional induction heating cooker.

[Explanation of symbols]

 2 Inverter Circuit 2a First Switching Means 2b Second Switching Means 3 First Driving Means 4 Second Driving Means 5 Oscillating Means 6 Driving Time Setting Means 7 Driving Power Supply for Second Driving Means 8 First Driving Power source for driving means 9 Charging means 11 Charging signal output means 12 Signal stopping means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masaji Kambara, 1006 Kadoma, Kadoma City, Osaka Prefecture, Matsushita Electric Industrial Co., Ltd. (72) Yuji Fujii, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 72) Inventor Tetsuro Nagaku 1006 Kadoma, Kadoma-shi, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. An inverter circuit having a first switching means connected to a high potential side of a DC power supply and a second switching means connected to a low potential side of the DC power supply, an oscillating means, and the oscillating means. Drive time setting means for setting the drive time of the first switching means and the second switching means by dividing the oscillation cycle set in 1., first drive means for driving the first switching means, and Second driving means for driving the second switching means, charging means for charging the driving power source of the first driving means while driving the second switching means, and charging signal output means The induction heating cooker, wherein the charging signal output means always controls the second switching means to be in a driving state for a predetermined time or more immediately before starting the inverter circuit. 2. An inverter circuit having first switching means connected to the high potential side of a DC power supply and second switching means connected to the low potential side of the DC power supply, oscillating means, and the oscillating means. Drive time setting means for setting the drive time of the first switching means and the second switching means by dividing the oscillation cycle set in 1., first drive means for driving the first switching means, and A second driving means for driving the second switching means, a charging means for charging the driving power source of the first driving means while driving the second switching means, and a signal stopping means. The induction heating cooker, wherein the signal stopping means controls the first switching means to be in a stopped state for a predetermined time or more after the inverter circuit is activated.