JP3780894B2 - Microwave generator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for generating a microwave by driving a magnetron, and more particularly to a method of driving a plurality of magnetrons simultaneously by a single high voltage power source.
[0002]
[Prior art]
Conventionally, as this type of microwave generator, there has been one as described in FIGS . 8 and 9 , for example. FIG. 8 is for driving two magnetrons with a conventional microwave generator.
[0003]
The microwave generator of FIG. 8 requires a dedicated power source for each magnetron, and if there are two magnetrons, two power sources are also required. That is, two high-voltage transformers 7, high-voltage capacitors 8, and high-voltage diodes 9 constituting the power supply are also required. Since these parts handle large amounts of power at high voltage, the cost burden is large in terms of size and weight.
[0004]
FIG. 9 employs an inverter power supply system as a power supply for driving the magnetron. That is, a commercial power source is a rectifier circuit 14, a choke 13 and a smoothing capacitor 12 constituting a smoothing circuit, a resonance capacitor 11 for high-frequency oscillation, a switching element 10 that controls resonance and performs a switching operation based on an input signal 15, an inverter power source control circuit 16 for driving the same. Conventionally, these require the same number as the number of magnetrons, and are expensive and large in volume.
[0005]
[Problems to be solved by the invention]
Therefore, a means for connecting and driving a plurality of magnetrons to one power source is required.
[0006]
However, when a plurality of magnetrons are connected in parallel with a single power source, there is a difference in the characteristics of each magnetron, so a difference occurs in the currents flowing between the magnetrons, making it impossible to achieve a balance. In particular, as a special characteristic of the operation characteristics of the magnetron, current does not flow up to a certain predetermined voltage, but when the voltage exceeds a certain predetermined voltage, current suddenly flows, and the current greatly changes with a slight voltage change. Because of this characteristic, the difference in current flowing through each magnetron is large, and the balance is greatly lost.
[0007]
An object of the present invention is to solve the problem of unbalance due to characteristic variations of individual magnetrons, and to provide a microwave generator in which each magnetron operates stably while maintaining a certain balance. .
[0008]
It is another object of the present invention to stably start up to a desired power while maintaining the balance of each magnetron at the time of startup.
[0009]
[Means for Solving the Problems]
In order to solve the above-described conventional problems, a microwave generator according to the present invention includes a plurality of magnetrons, a high-voltage power supply capable of supplying high-voltage power to these magnetrons and controlling the amount of power supplied, and a magnetron Operating characteristic variable means capable of changing the operating characteristics of each of the magnetrons, anode current detecting means for each magnetron, one of a plurality of magnetrons as a standard magnetron, and the anode of the standard magnetron detected by the anode current detecting means An operation characteristic variable control means for comparing the current signal and the anode current signal detected by the anode current detection means of another magnetron and controlling the operation characteristic variable means of the magnetron based on the result is provided.
[0010]
Further, at the time of start-up, instead of starting up to a desired power at once, it is configured to start up with a low power once and balance each magnetron and then start up to the desired power.
[0011]
Another method is to gradually start up at a slower rate than the balance of each magnetron at startup.
[0012]
This enables stable operation and activation by the balance between the anode current flowing through each mug Neto Ron is maintained. As a result, a plurality of magnetrons can be driven by one power source.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
According to the first aspect of the present invention, there is provided a standard magnetron having a fixed operating characteristic among a plurality of magnetrons that generate microwaves, a magnetron capable of changing operating characteristics other than the standard magnetron, and the standard magnetron. A high voltage power supply for supplying high-voltage power to these magnetrons, operating characteristic variable means for changing the operating characteristics of the magnetron whose operating characteristics can be changed, anode current detecting means for individual magnetrons, The standard magnetron anode current signal detected by the detection means is compared with the anode current signal detected by the other magnetron anode current detection means, and the anode current of the other magnetron is equal to the anode current of the standard magnetron. Operating characteristics for controlling the operating characteristics variable means And a change control unit, the high voltage power supply is used to control the supply amount of power.
[0014]
As a result, stable start-up and operation can be achieved without causing a loss in the balance of the anode current caused by the special operational characteristics of the magnetron and variations in individual operational characteristics.
[0015]
According to the second 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 constituted by a capacitor, a switching element, and the like.
[0016]
The invention according to claim 3 is particularly activated by a high-voltage power source capable of controlling the power supplied to the microwave generator, at a time lower than the desired input power at the time of startup, and the balance of the anode current of each magnetron is After being taken, the configuration is such that the desired input power is raised.
[0017]
The invention described in claim 4 is a high-speed power supply capable of controlling the power supplied to the microwave generator, particularly at the time of starting up to a desired input power at the time of start-up so that the anode current of each magnetron can be balanced. It is configured to be slower than this, and stable startup is possible.
[0018]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0019]
(Example 1)
FIG. 1 is a circuit configuration diagram of a microwave generator according to an embodiment of the present invention.
[0020]
In FIG. 1, reference numeral 7 denotes a high voltage transformer for supplying high voltage power to the magnetron. The high voltage capacitor 8 and the high voltage diode 9 constitute an output voltage rectifier circuit, and the high voltage power is supplied to the magnetron. A diode bridge 14 that rectifies the commercial power supply, a choke 13 that smoothes the rectified power, and a smoothing capacitor 12 are provided. A resonance circuit is formed by the resonance capacitor 11 and the high-voltage transformer 7, and the switching element 10 is turned on and off. An inverter power supply for converting to high frequency power is configured. Based on the signal from the input current detection circuit 15, the inverter power supply control circuit 16 controls ON / OFF of the switching element 10. As a result, the magnitude of the input current can be freely controlled. Two magnetrons, a standard magnetron 1 and a variable operating characteristic magnetron 2, are connected in parallel. Reference numeral 5 denotes an anode current detection means for the variable operating characteristic magnetron 2, and reference numeral 6 denotes an anode current detection means for the standard magnetron 1. Reference numeral 4 denotes an anode current signal difference detection amplification circuit that compares the signals of the two anode current detection means 5 and 6 and outputs the difference as a voltage. Reference numeral 3 denotes an operation characteristic according to the voltage of the anode current signal difference detection amplification circuit 4. Coil current control means for controlling the current of the magnetic field adjusting coil 2-1 of the variable magnetron 2. The anode current signal difference detection amplification circuit 4 and the coil current control means 3 constitute an operation characteristic variable control means.
[0021]
FIG. 2 shows the structure of the operation characteristic variable magnetron 2. A plurality of vanes 2-2 are radially attached to the annular anode block 2-3 to form an oscillation space. 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 denotes an antenna that radiates microwave energy generated in the oscillation space. The cathode 2-8 is a direct heating type and is composed of a heater, and a cathode heating current is supplied from the cathode terminal 2-7. Reference numeral 2-1 denotes a magnetic field adjusting coil that adjusts the magnetic field strength applied to the oscillation space by being combined with the magnet 2-5, and adjusts the strength of the magnetic field by the current. Further, the change in the strength of the magnetic field is a change in the voltage of the operation characteristic of the variable operation characteristic magnetron 2. That is, if the magnetic field is strong, the operating voltage is high, and if the magnetic field is weak, the operating voltage is low.
[0022]
About the microwave generator comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.
[0023]
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, current suddenly starts to flow, and the current changes greatly with respect to the change in voltage. The operating voltage is high when the magnetic field applied to the oscillation space is strong, and low when the magnetic field is weak. In general, magnetrons vary in operating voltage due to variations in the magnetic field strength of the magnets.
[0024]
Therefore, when two magnetrons are operated as in the microwave generator in the embodiment of the present invention, a difference occurs in the operation 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 anode current Ia1 of the standard magnetron 1 is small with respect to the operating voltage Vo. The anode current Ia2 of the variable magnetron 2 is increased, and a large difference is generated between the two so that the balance is lost. FIG. 4C shows a case where the operational characteristics of the magnetrons are reversed and the magnitudes of Ia1 and Ia2 are reversed and the balance is greatly lost.
[0025]
Therefore, as shown in FIG. 4D, the anode current Ia1 of the standard magnetron 1 and the anode current Ia2 of the variable operating characteristic magnetron 2 are compared. If Ia2> Ia1, the magnetic field is increased by the magnetic field adjusting coil 2-1, and the operating voltage is increased. So that it matches the operating characteristics of the standard magnetron 1. By doing so, Ia1 and Ia2 are equal, and a balanced and stable operation is achieved. Conversely, if Ia2 <Ia1, the magnetic field adjusting coil 2-1 weakens the magnetic field and lowers the operating voltage, so that Ia2 = Ia1 and a balanced and stable operation can be achieved.
[0026]
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 its circuit configuration means. Reference numeral 5 denotes an anode current detecting means of the variable operating characteristic magnetron 2 and shows its circuit configuration. Either anode current detection means outputs 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 corresponding to the difference. Reference numeral 3 denotes coil current control means for controlling the magnitude and polarity of the current value that flows through the magnetic field adjustment coil 2-1 in response to the signal from the anode current signal difference detection amplification circuit 4. With the above configuration, the difference between the anode currents Ia1 and Ia2 of each magnetron is detected, and the current of the magnetic field adjustment coil 2-1 is controlled so that the difference is eliminated. As a result, the two magnetrons can operate stably while maintaining a balance. The anode current signal difference detection amplification circuit 4 and the coil current control means 3 constitute an operation characteristic variable control means.
[0027]
5, 6, and 7 show the rising state of the anode current of each magnetron at start-up.
[0028]
FIG. 5 shows the elapsed time t on the horizontal axis and the anode current value I on the vertical axis, and shows the rising state at the start-up of the anode current Ia1 of the standard magnetron 1 and the anode current Ia2 of the operating characteristic variable magnetron 2. Suddenly, when starting up at a desired power, each anode current value is not immediately balanced and there is a time delay, so that one of the currents becomes too large, causing a phenomenon of excessive current and unstable oscillation.
[0029]
Means for preventing this phenomenon and starting up stably are shown in FIGS.
[0030]
In FIG. 6, at the time of start-up, the power supply is once raised at a current value lower than the desired current value, and is raised to the desired current value after both are balanced. Thereby, it can prevent that an excessive electric current flows into one side.
[0031]
FIG. 7 shows a means for starting up gradually rather than starting up at the time of startup, and means for starting up at a speed slower than the speed at which the balance can be achieved.
[0032]
In either method, the start-up at the time of start-up can prevent an excessive current and perform stable start-up.
[0033]
【The invention's effect】
As described above, according to the first to fourth aspects of the present invention , a stable operation drive can be performed while maintaining the balance of a plurality of magnetrons supplied with power from one high-voltage power supply .
[0034]
In addition, it is possible to start up stably at startup.
[Brief description of the 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 an operation characteristic variable magnetron in the microwave generator according to the first embodiment of the present invention. FIG. 4 is a diagram showing a mechanism of a control system for realizing a microwave generator of the present invention. FIG. 4 is an operational characteristic diagram showing the operation of a magnetron in the microwave generator of the present invention. 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. Circuit diagram [Fig. 9] Circuit diagram of a conventional microwave generator [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Standard magnetron 2 Operation characteristic variable type magnetron 2-1 Magnetic field adjustment coil 3 Coil current control means 4 Anode current difference detection amplification circuit 5 Operation characteristic variable type magnetron anode current detection means 6 Standard magnetron anode current detection means 7 High voltage transformer DESCRIPTION OF SYMBOLS 10 Switching element 11 Resonance capacitor 16 Inverter power supply control circuit

Claims (4)

Among a plurality of magnetrons that generate microwaves , one standard magnetron whose operating characteristics are fixed, a magnetron whose operating characteristics other than the standard magnetron can be changed, and high-voltage power are supplied to these magnetrons including the standard magnetron to a high voltage power supply, wherein the operating characteristic varying means operating characteristics make change the operating characteristics of the changeable magnetron, a detection unit of the anode current of the individual magnetron, a standard magnetron detected by the detecting means of the anode current The anode current signal is compared with the anode current signal detected by the anode current detection means of another magnetron, and the operation characteristic variable means is set so that the anode current of the other magnetron becomes equal to the anode current of the standard magnetron. Operating characteristic variable control means to control, Voltage power microwave generating apparatus and controls the supply amount of power. 2. The micro-voltage according to claim 1, wherein the high-voltage power source capable of controlling the amount of power supplied is realized by an inverter power source configured by a switching element, a capacitor, or the like, such as a rectified DC power of a commercial power source or a DC voltage of a battery. Wave generator.   3. The microwave generator according to claim 1, wherein the microwave generator is configured to start up at a power lower than a predetermined input power at the time of start-up, and to increase to a predetermined input power after balancing the anode current of each magnetron.   3. The microwave generator according to claim 1, wherein, at the time of start-up, the speed at which the power is raised to a predetermined input power is set to be slower than the speed at which the anode current of each magnetron can be balanced.

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