CN107294503A - An Impedance Automatic Tuning System Capable of Real-time Monitoring and Automatic Compensation - Google Patents

Abstract

The invention relates to the technical field of impedance automatic tuning of a broadband high-power radio frequency amplifier, in particular to an impedance automatic tuning system which can be applied to a broadband high-frequency power source, controls and adjusts the parameters of a matching network by monitoring the detuning angle of the output impedance of a pre-amplifier in real time to realize the automatic compensation function and is used for solving the detuning of the pre-impedance of a tetrode; the invention mainly comprises a control unit and a high-frequency power source which are connected through an impedance resonance matching network, and mainly relates to an automatic tracking impedance tuning technology, in particular to an automatic tracking impedance tuning technology which can control and adjust parameters of the matching network by monitoring the detuning angle of output impedance of a pre-amplifier in real time and automatically compensate impedance change caused by a quadrupole gate capacitor Ckg1 in a wide frequency band, so that the input impedance of a tetrode gate can be always ensured to be in a resonance matching state in the whole wide frequency band working range, and the working efficiency and the whole machine performance of a high-power tetrode amplifier can be greatly improved.

Description

An Impedance Automatic Tuning System Capable of Real-time Monitoring and Automatic Compensation

technical field

The invention relates to the technical field of automatic tuning of the impedance of a broadband high-power radio frequency amplifier, in particular to an automatic compensation function that can be applied to a broadband high-frequency power source by monitoring the detuning angle of the output impedance of the pre-amplifier in real time to control and adjust the parameters of the matching network. An impedance auto-tuning system capable of real-time monitoring and auto-compensation to solve the impedance detuning of the tetrode front stage.

Background technique

In the fields of high-frequency power sources of certain particle accelerators and high-power short-wave transmitters for microwave communications, or in the field of proton and heavy ion accelerators in the field of basic scientific experimental research, as well as space radiation effects and accelerator-driven clean nuclear energy devices, high frequency and high power are required. Electronic tetrode amplifiers work in a wide frequency range. For example, ferrite-loaded high-frequency accelerating cavities used in proton and heavy ion synchrotrons and medical accelerator cancer treatment devices require high-frequency power sources to have In order to ensure the normal and reliable operation of the high frequency power source in the wide frequency band, the impedance matching of all levels of the power amplifier is very important. Due to the existence of the grid cathode capacitance Ckg1 of the tetrode, when the frequency sweep is working The input impedance of the gate will change with the frequency, causing the impedance detuning of the front stage of the tetrode, which will increase the reflected power of the preamplifier, affect the power output of the power source, and cause the overall performance of the power source to deteriorate; in order to compensate for the For detuning caused by this, the usual technique is to install a passive impedance matching network between the preamplifier and the tetrode amplifier, which is feasible for power amplifiers with narrowband operating frequencies, but due to the The device bandwidth is limited, and the non-adjustable impedance matching network cannot meet the requirements of broadband matching, so it is not suitable for amplifiers that work in a wide frequency band. Although the Chinese patent number is 201410300942.1, the patent name is a wideband high-power radio frequency transmitter tuning method, which discloses a broadband high-power radio frequency transmitter tuning method, which involves an automatic tuning technology, that is, in the broadband high-power When the power radio frequency transmitter is running in short pulses, the data acquisition system is used to monitor the working status of the electronic tube amplifiers at all levels of the transmitter, and the parameters of the collected electronic tubes are analyzed to feedback and adjust the tuning components of the transmitter, so that the electronic tube amplifiers of the transmitter can achieve the best Working status and maximum power output. Although this method can scientifically and accurately reflect the working status of the transmitter tube amplifier in the form of data charts, it cannot perform real-time monitoring and automatic impedance tuning.

Contents of the invention

In order to overcome the deficiencies in the prior art, the present invention aims to provide a field of high-power short-wave transmitters used in high-frequency power sources of particle accelerators and microwave communications, or proton and heavy ion accelerators in the field of basic science experiment research, and Space radiation effects and accelerator-driven clean nuclear energy devices are used to monitor the detuning angle of the output impedance of the pre-amplifier in real time to control and adjust the parameters of the matching network for automatic compensation to solve the detuning of the tetrode pre-stage impedance. And auto-compensating impedance auto-tuning system.

In order to achieve the above purpose, the technical solution adopted by the present invention is: an impedance automatic tuning system capable of real-time monitoring and automatic compensation, the impedance automatic tuning system mainly includes a control unit and a high-frequency power source connected through an impedance resonance matching network , wherein the control unit is connected to the front end of the impedance resonance matching network, and the high frequency power source is connected to the rear end of the impedance resonance matching network.

The high-frequency power source mainly includes a pre-amplifier, a tetrode amplifier and a high-frequency load. The pre-amplifier is connected to the tetrode amplifier through an impedance resonance matching network to provide input signal drive for the tetrode. The grid-cathode capacitance Ckg1 is connected with the grid input impedance to form the input impedance of the tetrode amplifier, and is connected with the impedance resonance matching network, and the high-frequency load is connected with the anode output of the tetrode.

The impedance resonance matching network is an adjustable inductance network made of ferrite rings, including four inductors made of ferrite rings, windings are wound around the ferrite rings, and the four ferrite rings are The body ring shares a 120T bias coil. By changing the current in the bias coil on the ferrite ring, the bias magnetic field strength in the ferrite ring can be adjusted to change the permeability of the ferrite ring. As a result, the inductance value formed by the ferrite ring and the winding changes, so the inductance value of the matching network can be adjusted by controlling the bias current, and the detuning of the grid input impedance caused by the frequency change can be neutralized and compensated, thereby realizing Automatic tuning and matching of gate impedance.

The control unit mainly includes a phase detector, a controller and a magnetic bias power supply. The phase detector is used to detect the phase difference of the output impedance of the high-frequency power source preamplifier. The phase detector is located at the front end of the controller, and the control unit The output of the controller is connected to the bias power supply. The controller function is realized by FPGA programming. In order to improve the anti-interference ability of the remote transmission of control signals, optical cable digital communication is used between the controller and the bias power supply; the bias power supply and impedance matching The excitation coils of the network are connected, and the output current of the bias current source is controlled by comparing the phase difference between the input and output signals of the pre-amplifier to adjust the inductance in the matching network and compensate for the phase difference.

The two ferrite rings are a pair, and the coils on the two ferrite rings are wound in antiparallel, so that the induced voltages generated by the bias current in the inductance coil cancel each other out.

There are 6 windings on each ferrite ring, and the number of windings depends on the inductance demand of the matching network.

Each ferrite ring is wound with a winding with the same number of turns.

The output current of the bias power supply is determined by the tuning range of the network, and the range is between 0 and 10A.

The impedance resonance matching network has an impedance transformation function, which transforms the large-value output impedance of the pre-amplifier into a small-value gate input impedance to ensure impedance matching between the two stages of amplifiers.

The impedance resonance matching network has a 4:1 impedance transformation function, which transforms the 800Ω output impedance of the pre-amplifier into a 200Ω gate input impedance.

The controller is a PID controller.

The impedance automatic tuning system can control and adjust the parameters of the matching network by monitoring the detuning angle of the output impedance of the preamplifier in real time, and automatically compensate the impedance change caused by the tetrode grid capacitance Ckg1 in a wide frequency band.

The beneficial effects of the present invention are reflected in: the present invention is mainly an automatic tracking impedance tuning technology, more specifically, it can control and adjust the parameters of the matching network by monitoring the detuning angle of the output impedance of the preamplifier in real time, and automatically compensate the tetrode The impedance change caused by the gate capacitance Ckg1 in the wide frequency band makes it possible to always ensure that the input impedance of the tetrode gate is in a resonant matching state in the entire wide frequency band working range, thereby greatly improving the working efficiency of the high-power tetrode amplifier and Machine performance.

Description of drawings

Fig. 1 is a schematic diagram of logical connection of the present invention.

Fig. 2 is a schematic diagram of an impedance resonance matching network in the present invention.

detailed description

The specific embodiment of the present invention is described in detail below in conjunction with accompanying drawing:

As shown in Figure 1-2, an impedance automatic tuning system capable of real-time monitoring and automatic compensation, the impedance automatic tuning system mainly includes a control unit and a high-frequency power source connected through an impedance resonance matching network, wherein the control unit is connected to At the front end of the impedance resonance matching network, the high frequency power source is connected at the back end of the impedance resonance matching network.

The high-frequency power source mainly includes a pre-amplifier, a tetrode amplifier and a high-frequency load. The pre-amplifier is connected to the tetrode amplifier through an impedance resonance matching network to provide input signal drive for the tetrode. The grid-cathode capacitance Ckg1 is connected with the grid input impedance to form the input impedance of the tetrode amplifier, and is connected with the impedance resonance matching network, and the high-frequency load is connected with the anode output of the tetrode.

The impedance resonance matching network is an adjustable inductance network surrounded by ferrite. The impedance resonance matching network has an impedance conversion function, which converts the large-value output impedance of the pre-amplifier into a small-value gate input impedance, ensuring Impedance matching between the two amplifiers; the impedance resonance matching network has a 4:1 impedance transformation function, which transforms the 800Ω output impedance of the preamplifier into a 200Ω gate input impedance.

It includes four inductors surrounded by ferrite, each of which is wound with the same number of turns, and the four ferrite rings share a 120T bias coil, more specifically, each There are 6 windings on each ferrite ring, and the number of turns of the winding depends on the demand of the matching network for inductance; every two of the ferrite rings are a pair, and the coils on the two ferrite rings Using anti-parallel winding, the induced voltage generated by the bias current in the inductor coil cancels each other; by changing the current in the bias coil on the ferrite ring, the bias magnetic field strength in the ferrite ring can be adjusted. Change the magnetic permeability of the ferrite ring, resulting in the change of the inductance value formed by the ferrite ring and the winding, so the inductance value of the matching network can be adjusted by controlling the bias current, and the gate input caused by the frequency change The detuning of the impedance is neutralized and compensated, and then the automatic tuning and matching of the grid impedance is realized.

The control unit mainly includes a phase detector, a controller and a magnetic bias power supply. The phase detector is used to detect the phase difference of the output impedance of the high-frequency power source preamplifier. The phase detector is located at the front end of the controller, and the control unit The device is a PID controller, the output of the controller is connected to the bias power supply, and the output current of the bias power supply is determined by the tuning range of the network, and the range is between 0 and 10A; the described controller function is realized by FPGA programming, in order to improve The anti-interference ability of the remote transmission of the control signal, the optical cable digital communication is used between the controller and the bias power supply; The output current of the magnetic current source can adjust the inductance in the matching network to realize the compensation of the phase difference; the impedance automatic tuning system can control and adjust the parameters of the matching network by monitoring the detuning angle of the output impedance of the preamplifier in real time, and automatically compensate The impedance change caused by the grid capacitance Ckg1 of the tetrode in a wide frequency band.

The present invention can control and adjust the parameters of the matching network by monitoring the detuning angle of the output impedance of the pre-amplifier in real time, and automatically compensate the impedance change caused by the grid capacitance Ckg1 of the tetrode in a wide frequency band. The specific working principle is as follows:

First of all, the impedance resonance matching network in the present invention adopts an adjustable inductance network surrounded by ferrite, by changing the current in the bias coil on the ferrite ring, the bias magnetic field strength in the ferrite ring is adjusted, Change the magnetic permeability of the ferrite ring, resulting in the change of the inductance value formed by the ferrite ring and the winding, so the inductance value of the matching network can be adjusted by controlling the bias current, and the gate input caused by the frequency change The detuning of the impedance is neutralized and compensated, and then the automatic tuning and matching of the grid impedance is realized.

At the same time, the impedance resonance matching network is composed of two pairs of inductance surrounded by 4 ferrites, as shown in Figure 2, each ferrite ring is wound with 6 turns of winding, and the number of turns of the winding depends on the inductance of the matching network. Requirements, 4 ferrite rings share a bias coil (120T), the output current of the bias power supply is determined by the tuning range of the network, the output current range is 0~10A, in order to offset the influence of the bias magnetic field on the RF circuit, Every two ferrite rings are a pair, and the coils on these two rings are wound in reverse parallel, so that the induced voltages generated by the bias current in the inductance coil cancel each other out, and do not affect the high-frequency circuit.

In order to match the impedance between the preamplifier and the final tetrode amplifier, the impedance resonance matching network has a 4:1 impedance transformation function in addition to the tuning function, which can transform the 800Ω output impedance of the preamplifier to 200Ω The gate input impedance of the gate ensures the impedance matching between the two amplifiers. Since the output load impedance of the pre-amplifier is mainly composed of the input resistance of the tetrode amplifier, the grid cathode capacitance Ckg1 of the tetrode and the impedance of the impedance resonance matching network, when the input and output voltages of the pre-amplifier are guaranteed to be in phase, that is When the phase difference tends to zero, the output impedance of the pre-amplifier is pure resistance, and the grid of the tube is in the best tuning state.

Once the input impedance of tetrode grid cathode capacitance Ckg1 changes due to frequency changes or other conditions, causing the grid impedance of the electron tube to detune, a phase difference will be generated between the input and output voltages of the pre-amplifier, determined by the identification The phase difference between the input and output signals of the pre-amplifier is detected by the phase detector, and the output current of the bias current source is controlled after being processed by the PID controller. The controller will control the iron according to the phase difference signal detected by the phase detector. The bias current of the oxygen body ring, because the bias power supply is connected to the exciting coil of the impedance resonance matching network, the change of the current in the coil will change the inductance in the impedance resonance matching network, thereby compensating the capacitive reactance component in the impedance, Prompt the phase difference to be zero, and ensure that the input impedance of the quadrupole grid is always in a resonance state, that is, a pure resistance state. The function of the controller in the present invention is realized by FPGA programming. In order to improve the anti-interference ability of the remote transmission of the control signal, the control Optical cable digital communication is used between the amplifier and the bias power supply; thus, the working efficiency and overall performance of the high-power tetrode amplifier can be greatly improved.

In summary, the present invention, as an automatic tracking impedance tuning technology, more specifically can control and adjust the parameters of the matching network by monitoring the detuning angle of the output impedance of the preamplifier in real time, and automatically compensate the tetrode grid capacitance Ckg1 in the broadband The impedance change caused in the band makes it possible to ensure that the input impedance of the tetrode amplifier is in a resonant matching state throughout the wide-band operating range, thereby greatly improving the working efficiency and overall performance of the high-power tetrode amplifier.

The above are only preferred embodiments of the present invention, and are not intended to limit the technical scope of the present invention. Those skilled in the art can make some deformations and modifications under the inspiration of this technical solution. Any modifications, equivalent changes and modifications made to the above embodiments by technical essence still belong to the scope of the technical solution of the present invention.

Claims (9)

1. a kind of impedance automatic tuning system that can in real time monitor and compensate automatically, it is characterised in that：Described impedance is adjusted automatically Humorous system mainly includes control unit and the high frequency power source connected by impedance resonance matching network, and wherein control unit is connected In impedance resonance matching network front end, high frequency power source is connected to impedance resonance matching network rear end；

Described high frequency power source mainly includes pre-amplifier, tetrode amplifier and high frequency load, and pre-amplifier passes through Impedance resonance matching network is connected with tetrode amplifier, and input signal driving, the grid-to-cathode capacitance of tetrode are provided for tetrode Ckg1 connects and composes the input impedance of tetrode amplifier with grid input impedance, is connected with impedance resonance matching network, high frequency The anode output with tetrode is loaded to be connected；

Described impedance resonance matching network is the adjustable inductance network turned to by ferrite core, including four ferrite cores Winding is wound with the inductance turned to, described ferrite core, and four ferrite cores share 120T magnetic bias coil, lead to Cross the electric current in magnetic bias coil on change ferrite core, it is possible to adjust the biased magnetic field strength in ferrite core, make ferrite The magnetic conductivity of ring changes, and the inductance value for causing ferrite core to be constituted with winding changes, therefore can be inclined by control Magnetoelectricity stream adjusts the inductance value of matching network, the off resonance for changing the grid input impedance caused due to frequency neutralize with Compensation, and then realize the automatic resonance matching of grid impedance；

Described control unit mainly includes phase discriminator, controller and magnetic bias power supply, and described phase discriminator is to high frequency power The phase difference of source pre-amplifier output impedance is detected that phase discriminator is located at controller front end, the output of controller and magnetic bias Power supply is connected, and described controller function is by FPGA programming realizations, to improve the antijamming capability of control signal remote transmission, control Optical cable digital communication is used between device processed and magnetic bias power supply；Magnetic bias power supply connects with the magnet exciting coil of impedance matching network, passes through The phase difference for comparing pre-amplifier input and output signal goes to control the output current in bias current source to realize to matching network In inductance be adjusted, realization phase difference is compensated.

2. a kind of impedance automatic tuning system that can in real time monitor and compensate automatically according to claim 1, its feature exists In：Described ferrite core each two is that the coil on a pair, the two ferrite cores uses reverse parallel connection coiling, makes magnetic bias electricity The induced voltage produced in inductance coil is flowed to cancel each other.

3. a kind of impedance automatic tuning system that can in real time monitor and compensate automatically according to claim 1, its feature exists In：6 circle windings are wound with each ferrite core, the number of turns of winding depends on demand of the matching network to inductance value.

4. a kind of impedance automatic tuning system that can in real time monitor and compensate automatically according to claim any one of 1-3, It is characterized in that：Number of turn identical winding is wound with described each ferrite core.

5. a kind of impedance automatic tuning system that can in real time monitor and compensate automatically according to claim 1, its feature exists In：The output current of described magnetic bias power supply determines that scope is between 0 ~ 10A by the tuning range of network.

6. a kind of impedance automatic tuning system that can in real time monitor and compensate automatically according to claim 1, its feature exists In：Described impedance resonance matching network has impedance mapping function, the big value output impedance of pre-amplifier is transformed to small The grid input impedance of value, it is ensured that the impedance matching between dual-stage amplifier.

7. a kind of impedance automatic tuning system that can in real time monitor and compensate automatically according to claim 6, its feature exists In：Described impedance resonance matching network has 4：1 impedance mapping function, 800 Ω output impedances of pre-amplifier are become It is changed to 200 Ω grid input impedances.

8. a kind of impedance automatic tuning system that can in real time monitor and compensate automatically according to claim 1, its feature exists In：Described controller is PID controller.

9. a kind of impedance automatic tuning system that can in real time monitor and compensate automatically according to any one of right 1,6,7, its It is characterised by：Described impedance automatic tuning system can be controlled by monitoring the Tune-out angle of pre-amplifier output impedance in real time The parameter of system adjustment matching network, the impedance variations that automatic compensation tetrode grid capacitance Ckg1 is caused in broadband.