JP2003115373A - Microwave generating equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drive two or more magnetrons simultaneously while maintaining desired balance with one high-voltage power supply. SOLUTION: By providing an operating characteristic variable type magnetron 2, which can change the operating characteristic by a standard magnetron 1 and an operating characteristic variable means 2-1, the anode current detection means 5 and 6 of each magnetrons, and the operating characteristic variable control means to compare the output signal of each the anode current detection means 5 and 6, and to control the operating characteristic variable means (coil for magnetic field adjustment) 2-1 based on this result, two or more magnetrons can be driven steady with sufficient balance. Moreover, by starting it gradually, stable starting can be done.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for driving a magnetron to generate a microwave, and more particularly to a method for driving a plurality of magnetrons simultaneously by using one high voltage power source.

[0002]

2. Description of the Related Art Heretofore, as a microwave generator of this type, there has been one as shown in FIGS. 8 and 9, for example. FIG. 8 is for driving two magnetrons with a conventional microwave generator.

The microwave generator shown in FIG. 8 requires a dedicated power source for each magnetron, and two power sources if two magnetrons are required. That is, two high-voltage transformers 7, a high-voltage capacitor 8 and a high-voltage diode 9 which constitute the power supply were required. Since these parts handle a large amount of electric power at high voltage, the cost burden becomes large in terms of size and weight.

Further, FIG. 9 employs an inverter power supply system as a power supply for driving the magnetron. That is, a commercial power supply includes a rectifier circuit 14, a choke 13 and a smoothing capacitor 12 that form a smoothing circuit, a resonant capacitor 11 for high-frequency oscillation, a switching element 10 that controls resonance and performs switching operation based on an input signal 15. The inverter power supply control circuit 16 for driving this is provided. If these are also conventional,
The same number as the number of magnetrons was required, which was expensive and large in volume.

[0005]

Therefore, a means for connecting and driving a plurality of magnetrons to one power supply is required.

However, when a plurality of magnetrons are connected in parallel by one power source, there is a difference in the characteristics of each magnetron, so that a difference occurs in the currents flowing between the magnetrons, which makes the balance unbalanced. In particular, as a peculiarity of the operating characteristics of the magnetron, the current does not flow up to a certain predetermined voltage, but when the current exceeds a certain predetermined voltage, the current suddenly flows out, and the current greatly changes with a slight voltage change. Due to this characteristic, a large difference occurs between the currents flowing through the magnetrons, and the balance is greatly lost.

The present invention solves the problem of the imbalance in balance due to the characteristic variations of the individual magnetrons, and provides a microwave generator that operates stably while maintaining a constant balance between the magnetrons. To aim.

Another object of the present invention is to stably start up to a desired electric power while maintaining the balance of each magnetron at the time of starting.

[0009]

In order to solve the above-mentioned conventional problems, the microwave generator of the present invention supplies a plurality of magnetrons and high-voltage power to these magnetrons and controls the supplied power amount. A high-voltage power supply capable of changing the operating characteristics of the magnetron, a means for changing the operating characteristics of the magnetron, and a detecting means of the anode current of each magnetron,
One of the plurality of magnetrons is provided as a standard magnetron, and the anode current signal of the standard magnetron detected by the anode current detecting means is compared with the anode current signal detected by the anode current detecting means of another magnetron. The operation characteristic changing control means for controlling the operation characteristic changing means of the magnetron based on the result is provided.

Further, at the time of start-up, the power is not raised to the desired power all at once, but is raised once with a low power to balance each magnetron and then to the desired power.

As another means, the magnetrons are gradually started at a slower speed than the speed at which each magnetron is balanced.

As a result, the balance between the anode currents flowing in the respective magnetrons is maintained, and stable operation and startup are possible. Further, as a result, a plurality of magnetrons can be driven by one power source.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 is a plurality of magnetrons that generate microwaves, a high voltage power supply that supplies high voltage power to these magnetrons, and operating characteristics that can change the operating characteristics of the magnetrons. Operation characteristic variable control for comparing the operation characteristic varying means with the varying means, the anode current detecting means of each magnetron, and the anode current signal detected by the anode current detecting means of each magnetron, and controlling the operation characteristic varying means based on the result. By providing the means, it is possible to stably start up and operate without losing the balance of the anode current caused by the peculiarity of the operating characteristics of the magnetron and the variation of the individual operating characteristics.

According to a second aspect of the present invention, a plurality of magnetrons for generating microwaves, a high voltage power source capable of supplying high voltage power to these magnetrons and controlling the amount of power supplied thereto, and operation of the magnetrons. The operating characteristic variable means capable of changing the characteristics, the anode current detecting means of each magnetron, and one standard magnetron among a plurality of magnetrons are provided, and the anode current signal of the standard magnetron detected by the anode current detecting means of the standard magnetron is provided. And an anode current signal detected by the anode current detecting means of another magnetron, and based on the result, the operating characteristic variable control means for controlling the operating characteristic varying means of the magnetron is provided.

As a result, the start-up and operation of the magnetron can be stably performed without causing the balance of the anode current to be lost due to the peculiarity of the operation characteristics of the magnetron and the variation of the individual operation characteristics.

According to the third aspect of the present invention, in particular, the high voltage power source capable of controlling the amount of power supplied to the microwave generator can be realized by an inverter power source composed of a capacitor, a switching element and the like.

According to a fourth aspect of the present invention, in particular, a high voltage power source capable of controlling the power supplied to the microwave generator is used to temporarily start at a power lower than a desired input power at the time of startup, and the anode current of each magnetron is started. It is configured so that the input power is increased to a desired value after being balanced.

According to a fifth aspect of the present invention, in particular, the high voltage power supply capable of controlling the power supply of the microwave generator controls the speed of raising the input power to a desired input power at the time of starting, and balances the anode currents of the magnetrons. With a configuration that is slower than the speed at which it can be taken, stable startup is possible.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a circuit configuration diagram of a microwave generator according to an embodiment of the present invention.

In FIG. 1, 7 is a high-voltage transformer for supplying high-voltage power to the magnetron. The output voltage of the high-voltage capacitor 8 and the high-voltage diode 9 constitute a voltage doubler rectifier circuit to supply high-voltage power to the magnetron. ing. And diode bridge 1 which rectifies commercial power
4, a choke 13 for smoothing the rectified power and a smoothing capacitor 12 are provided, and the resonance circuit is constituted by the resonance capacitor 11 and the high voltage transformer 7, and the switching element 10
Inverter power supply for converting to high-frequency power by the ON-OFF operation of is constructed. And input current detection circuit 1
Based on the signal of 5, the inverter power supply control circuit 16 controls ON / OFF of the switching element 10. This allows the magnitude of the input current to be freely controlled. The standard magnetron 1 and the variable operating characteristic type magnetron 2 are connected in parallel. Reference numeral 5 is an anode current detecting means of the variable operation characteristic magnetron 2, and 6 is an anode current detecting means of the standard magnetron 1. 4 is these 2
An anode current signal difference detecting / amplifying circuit 3 for comparing the signals of the individual anode current detecting means 5 and 6 and outputting the difference as a voltage, a magnetron 2 having a variable operating characteristic according to the voltage of the anode current signal difference detecting / amplifying circuit 4. It is a coil current control means for controlling the current of the magnetic field adjusting coil 2-1. The anode current signal difference detection / amplification circuit 4 and the coil current control means 3 constitute operation characteristic variable control means.

FIG. 2 shows the structure of the magnetron 2 with variable operating characteristics. A plurality of vanes 2-2 are radially attached to the annular anode block 2-3 to form an oscillation space. Reference numeral 2-4 is a magnetic pole and 2-5 is a magnet, which applies a magnetic field to the oscillation space. Reference numeral 2-6 is an antenna that radiates microwave energy generated in the oscillation space. Two
-8 is a cathode which is a direct heating type and is composed of a heater 2-
A cathode heating current is supplied from the cathode terminal 7. 2-1 is a magnetic field adjusting coil, which adjusts the magnetic field strength applied to the oscillation space by combining with the magnet 2-5, and the strength of the magnetic field is adjusted by the current. Further, the change in the strength of the magnetic field results in the change in the voltage of the operation characteristic of the operation characteristic variable magnetron 2. That is, when the magnetic field is strong, the operating voltage is high, and when the magnetic field is weak, the operating voltage is low.

The operation and action of the microwave generator configured as described above will be described below.

First, FIG. 4A shows the operating characteristics of the magnetron. The vertical axis represents voltage and the horizontal axis represents current. When the voltage exceeds the oscillation start voltage Vs, a current suddenly starts to flow, and the current changes greatly with the change in voltage. If the magnetic field applied to the oscillation space is strong, the operating voltage is high, and if it is weak, the operating voltage is low.
Generally, magnetrons have variations in operating voltage due to variations in magnetic field strength of magnets.

Therefore, when the two magnetrons are operated as in the microwave generator in the embodiment of the present invention, there is a difference in the operating characteristics between the individual magnetrons.
FIG. 4B shows a case where the operating characteristic M2 of the variable operating characteristic magnetron 2 is lower than the operating characteristic M1 of the standard magnetron 1, and the standard magnetron 1 with respect to the operating voltage Vo.
The anode current Ia1 is small and the anode current Ia2 of the variable operation characteristic magnetron 2 is large, so that a large difference occurs between the two and the balance is lost. Figure 4 (c)
Is Ia1 and Ia when the operating characteristics of each magnetron are opposite.
It shows the case where the magnitude of 2 is reversed and the balance is greatly lost.

Therefore, as shown in FIG. 4 (d), the anode current Ia1 of the standard magnetron 1 and the anode current Ia2 of the variable operation characteristic magnetron 2 are compared. Then, the operating voltage is raised to match the operating characteristics of the standard magnetron 1. By doing so, Ia1 and Ia2 become equal, and a balanced and stable operation is achieved. Conversely, Ia2
If <Ia1, by weakening the magnetic field by the magnetic field adjusting coil 2-1 and lowering the operating voltage, Ia2 = Ia1 and a balanced and stable operation can be performed.

FIG. 3 shows a mechanism of a control system for realizing the present invention. Reference numeral 6 in FIG. 3 denotes an anode current detection means of the standard magnetron 1 and shows a circuit configuration means thereof. Reference numeral 5 denotes an anode current detecting means of the magnetron 2 having a variable operating characteristic, the circuit configuration of which is shown. Both anode current detection means output a signal as a voltage. Reference numeral 4 denotes an anode current signal difference detection / amplification circuit that compares the anode current detection signals of the respective magnetrons and outputs an output signal according to the difference. Reference numeral 3 is a coil current control means for controlling the magnitude and polarity of the current value flowing in the magnetic field adjusting coil 2-1 in response to the signal from the anode current signal difference detection / amplification circuit 4. With the above configuration, the anode currents Ia1 and Ia2 of each magnetron
Is detected and the current of the magnetic field adjusting coil 2-1 is controlled so that the difference is eliminated. As a result, the two magnetrons can operate stably while maintaining balance. Further, the anode current signal difference detection / amplification circuit 4 and the coil current control means 3 constitute operation characteristic variable control means.

FIGS. 5, 6, and 7 show the rising state of the anode current of each magnetron at the time of startup.

FIG. 5 shows the elapsed time t on the horizontal axis and the anode current value I on the vertical axis. The anode current I of the standard magnetron 1 is shown.
a1 and anode current I of variable operating characteristic magnetron 2
The rising state at the time of starting of a2 is shown. Suddenly, when the power is started up with the desired power, the respective anode current values are not immediately balanced and there is a time delay, so that one of the currents becomes too large and an excessive current occurs, resulting in unstable oscillation.

Means for preventing this phenomenon and starting up stably are shown in FIGS.

In FIG. 6, at the time of start-up, the current value is once raised at a current value lower than the desired current value, and after both are balanced, the current value is raised to the desired current value. This can prevent an excessive current from flowing to one side.

FIG. 7 is a means for gradually starting up rather than all at the time of startup, and is a means for starting up at a slower speed than a balanced speed.

With either means, rising at the time of start-up prevents an excessive current and enables stable start-up.

[0034]

As described above, according to the invention described in claims 1 to 5, it is possible to drive a plurality of magnetrons with a good balance in one high voltage power source.

Also, stable startup can be performed at the time of startup.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a microwave generator according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional structure diagram of a magnetron having a variable operation characteristic in the microwave generator according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a mechanism of a control system for realizing the microwave generator of the present invention.

FIG. 4 is an operation characteristic diagram showing the operation of the magnetron in the microwave generator of the present invention.

FIG. 5 is a diagram showing changes in anode current at startup.

FIG. 6 is a diagram showing changes in anode current in the microwave generator of the present invention.

FIG. 7 is a diagram showing changes in anode current in the microwave generator of the present invention.

FIG. 8 is a circuit configuration diagram of a conventional microwave generator.

FIG. 9 is a circuit configuration diagram of a conventional microwave generator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Standard magnetron 2 Variable operation characteristic magnetron 2-1 Magnetic field adjustment coil 3 Coil current control means 4 Anode current difference detection / amplification circuit 5 Operating characteristic variable magnetron anode current detection means 6 Standard magnetron anode current detection means 7 High voltage transformer 10 Switching Element 11 Resonant Capacitor 16 Inverter Power Supply Control Circuit

Claims (5)

[Claims] 1. A plurality of magnetrons for generating microwaves, a high voltage power supply for supplying high voltage power to these magnetrons, operating characteristic changing means for changing the operating characteristics of the magnetrons, and an anode current of each magnetron. A microwave generator comprising: a detection means and an operation characteristic variable control means for comparing the anode current signal detected by the anode current detection means of each magnetron and controlling the operation characteristic variable means based on the result. 2. A plurality of magnetrons for generating microwaves, a high voltage power supply for supplying high voltage power to these magnetrons, operating characteristic changing means for changing the operating characteristics of the magnetrons, and anode currents of the individual magnetrons. The detecting means and one standard magnetron among a plurality of magnetrons are provided, and an anode current signal of the standard magnetron detected by the anode current detecting means and an anode current signal detected by the anode current detecting means of another magnetron are provided. And an operating characteristic variable control means for controlling the operating characteristic varying means based on the result of comparison,
A microwave generator characterized in that the high-voltage power supply controls the amount of power supplied. 3. The high-voltage power supply capable of controlling the amount of supplied power is realized by an inverter power supply configured by a rectified DC power of a commercial power supply or a DC voltage of a battery or the like by a switching element, a capacitor or the like. 1. The microwave generator according to 1 or 2. 4. The micro according to claim 1, wherein at the time of start-up, the power is once started at a power lower than a predetermined input power, and then the anode current of each magnetron is balanced, and then the power is raised to a predetermined input power. Wave generator. 5. The microwave generator according to claim 1 or 2, wherein the startup speed to a predetermined input power at startup is slower than the speed at which the anode current of each magnetron is balanced.