JP4122994B2 - Pulse generator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pulse generator used in a radar transmitter.
[0002]
[Prior art]
A pulse generator generally uses a choke coil, a diode, a switching element, a pulse shaping circuit, and a pulse transformer for a high-voltage DC power source and outputs it to a load, and is called a line type pulser. For example, Japanese Patent Laid-Open No. 8-308256 has a configuration diagram for a pulse radar, and FIG. 4 shows a configuration diagram of a pulse high-voltage power supply. In the figure, 1 is a synchronous signal generator, 20 is a high voltage power source, 22 is a choke coil, 4 is a diode, 5 is a switching element, 6 is a pulse forming circuit, 23 is a pulse transformer, and 7 is a magnetron.
[0003]
Next, the operation will be described. The DC voltage supplied from the high-voltage power supply 20 is applied to the anode of the switching element 5 and one end of the pulse shaping circuit (PFN) 6 through the charging choke coil 22 and the diode 4. The PFN is composed of several stages of L · C circuits, and the capacitance of the circuits is first charged by the voltage. When the signal from the synchronizing signal generator 1 is input to the gate of the switching element 5, the element is turned on, and the voltage charged in the capacitance is discharged. At the same time, the pulse width is determined by the L · C value of PFN and the number of stages. This pulse is boosted by the pulse transformer 23 and then applied to the cathode terminal of the magnetron 7 as a negative high voltage pulse.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 8-308256
[Problems to be solved by the invention]
The line type pulser uses PFN to determine the pulse width. FIG. 8 shows an output waveform of the high-voltage power supply when a line type pulser is used. Since the line type pulser is composed of multi-stage L · C circuits, a waveform at the time of discharge is formed by the sum of charges charged in the individual L · C circuits. (FIG. 8-A), (FIG. 8-B). In this case, the ripple current is superimposed on the load current, and the electron tube used as the load is modulated by the ripple current even when a normal high-frequency signal is input (FIG. 8C). Therefore, as shown in FIG. There has been a problem that the spectrum of the oscillation signal or the amplified signal is deteriorated.
[0006]
The present invention has been made to solve the above-described problems, and an object thereof is to suppress the spread of the spectrum of the transmission apparatus.
[0007]
[Means for Solving the Problems]
A pulse generator of a transmitter according to the present invention includes a capacitor bank connected in parallel to a high-voltage power supply, a high-voltage switch that can be turned on / off by an external control signal connected in series to the anode side of the high-voltage power supply, and a secondary An inductor for impedance matching between the pulse transformer and the load is provided between the side voltage booster and the pulse transformer that supplies current to the load, and the high voltage switch is turned on / off based on the control signal to thereby turn the pulse transformer 2 A pulse voltage is supplied to the load provided on the next side, and the impedance matching inductor has an inductance value that matches the impedance of the pulse transformer and the load so that the load current supplied to the load has a flat characteristic. When the load current is flat, a high frequency signal is input to the load to generate a pulse signal Those were Unishi.
Further, an energy absorbing means for the impedance matching inductor is provided.
Further, an RC circuit (also referred to as a surge absorption circuit or RC snubber circuit) is connected in parallel to the high voltage switch.
In addition, a resistor and a diode connected in series are added to both ends of the impedance matching inductor.
A series circuit of a resistor and a diode connected in parallel is added to the series circuit on the primary side of the impedance matching inductor and the pulse transformer.
In addition, a voltage-dividing resistor for monitoring the potential of the high-voltage power supply is installed, and a voltage stabilizing device is added between the high-voltage power supply and the high-voltage switch.
In addition, a current detector for current detection is mounted on the secondary side of the pulse transformer and connected to the control circuit.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
A first embodiment of the present invention will be described below with reference to FIG. In the figure, 101 is a high-voltage power source, 102 is a capacitor bank for supplying energy to a load, 103 is a pulse transformer for supplying a secondary boost and load current, 104 is a load, and a high-frequency signal input (RF IN) terminal 105 , A high frequency signal output (RF OUT) terminal 106 and an amplifier 107 are included. A control circuit 108 receives a trigger signal from an external control terminal (trigger terminal) 109. Reference numeral 110 denotes a high-voltage switch composed of a semiconductor element that is turned ON / OFF by the control circuit 108. Reference numeral 111 denotes a capacitor, and 112 denotes a resistor, which are formed in series and connected in parallel to the high voltage switch 110 as an RC snubber circuit. Reference numeral 113 denotes an inductor for impedance matching between the pulse transformer 103 and the load 104, which is provided between the pulse transformer 103 and the high voltage switch 110.
[0009]
Next, the operation will be described. When the high voltage switch 110 is turned on by inputting an external control signal (trigger signal) to the trigger terminal 109, energy is supplied to the load 104 from the capacitor bank 102 via the high voltage switch 110, the impedance matching inductor 113, and the pulse transformer 103. Supplied. At this time, an equivalent circuit of the high-voltage power supply 101, the impedance matching inductor 113, the pulse transformer 103, and the load 104 can be expressed as shown in FIG. The capacitor bank 102 may be regarded as a smoothing capacitor for the high-voltage power supply 101.
[0010]
When the inductance value of the impedance matching inductor 113 is selected so as to be close to critical braking (vibration and attenuation during a transient phenomenon), the load current is temporally the peak value of the ripple or sag (direct capacitor) as shown in FIG. For example, when the charge is supplied from the above, the line voltage is instantaneously reduced when the pulse width is long.
[0011]
The condition that the load current becomes critical braking is that the inductance value of the impedance matching inductor 113 is L1, the leakage inductance of the pulse transformer 103 is L2, and the pulse transformer 103 and the stray capacitance generated between the cathode of the load 104 and GND are combined. the capacitance C (provided that the combined capacitance primary side converted value of the pulse transformer 103), the primary side converted value of the load impedance is R, is ^{(L1 + L2) = 4CR 2} . Note (L1 + L2) <For 4CR ² load current is the vibration waveform. An RF signal is input to the high-frequency signal input terminal 105 during a flat period of this current, and finally, for example, a peak output of 250 KW and a pulse width of 0.5 μS to 3 μS are repeatedly output from the antenna via a radar transmitter (not shown). A pulse radio wave with a frequency of 1 KHz is emitted.
[0012]
On the other hand, when the high voltage switch 110 is turned off, the energy accumulated in the impedance matching inductor 113 is absorbed by the RC snubber circuit including the capacitor 111 and the resistor 112 via the pulse transformer 103, the load 104, and the capacitor bank 102. .
[0013]
The conventional PFN has realized the flat characteristics of the load current peak by setting the pulse width and changing the load current using a multi-stage L / C circuit. As shown in FIG. 8, the waveform has ripples as many as the number of LC circuits configured in multiple stages in a flat region. Since ripple indicates fluctuations in the high-frequency voltage, it leads to fluctuations in the high-frequency output, resulting in fluctuations in the peripheral high frequency with respect to the normal transmission frequency, and as shown in FIG. 9, the occupied bandwidth of the transmission frequency spectrum This leads to an increase in performance as radar radio waves.
Normally, the occupied bandwidth of this type of high-frequency output needs to be 99% or more with respect to the total average power radiated.
[0014]
As described above, the load current waveform can be improved to a flat load current waveform as shown in FIG. 3 by optimizing the impedance matching inductor 113 so as to be close to the critical braking.
[0015]
In addition, since an RC snubber circuit is added, the surge voltage applied to the high voltage switch 110 is reduced, so the number of series connections for increasing the breakdown voltage of the semiconductor switch element used in the high voltage switch 110 is reduced. There is an effect that can be done. Further, if the load 104 requires a high voltage pulse such as a magnetron or an oscillating tube, the same effect can be obtained.
[0016]
Embodiment 2. FIG.
In the first embodiment, RC snubber circuits are provided at both ends of the high-voltage switch 110 to absorb the energy stored in the impedance matching inductor 113. However, as shown in FIG. A case where 115 and a resistor 116 are provided will be described. In FIG. 4, the energy accumulated in the impedance matching inductor 113 newly generates a discharge route in which a closed loop is formed by the impedance matching inductor 113, the resistor 116 and the diode 115 when the high voltage switch 110 is OFF. That is, as shown in FIG. 5, when the closed loop is not present, the load current waveform is expressed as Isw, and the current waveform formed by the impedance matching inductor 113, the resistor 116, and the diode 115 as IR1 is expressed as IR1, and the closed loop is present. The load current waveform can be expressed by I0, and a steep falling characteristic of the load current waveform can be obtained when the load current falls. Although the RC snubber circuit shown in the first embodiment is not added in the second embodiment, an RC snubber circuit may be added when the surge voltage is further suppressed. Further, if the load 104 requires a high voltage pulse such as a magnetron or an oscillating tube, the same effect can be obtained.
[0017]
Embodiment 3 FIG.
In the second embodiment, the diode 115 and the resistor 116 are provided in parallel with the impedance matching inductor 113. However, as shown in FIG. 6, the diode 115 is connected in parallel with the primary side series circuit of the inductor 113 and the pulse transformer 103. A case where the resistor 116 is provided will be described. In this case, the energy accumulated in the impedance matching inductor 113 forms a closed loop of the impedance matching inductor 113, the pulse transformer 103, and the resistor 116 diode 115 when the high voltage switch 110 is OFF, and is discharged. As a result, only a part of the energy stored in the impedance matching inductor 113 is transferred to the high voltage switch 110, and the surge voltage can be suppressed. Although the RC snubber circuit shown in the first embodiment is not added in the third embodiment, an RC snubber circuit may be added when the surge voltage is further suppressed.
[0018]
Embodiment 4 FIG.
Further, the fourth embodiment will be described with reference to FIG. In the figure, 120 and 121 are voltage detection resistors, 122 is a voltage stabilization device, and 123 is a current detector for detecting current.
A voltage stabilizing device 122 is added between one end of the high-voltage power supply 101 and the high-voltage switch 110, and voltage detection resistors 120 and 121 are installed as voltage-dividing resistors at portions corresponding to the both-ends voltage of the high-voltage power supply 101, so The voltage divided to the stable potential is sent to the control terminal 124 of the voltage stabilizer 122 as a monitor voltage. At this time, when the high voltage switch 110 is operated, the voltage stabilizing device 122 can generate a voltage corresponding to the instantaneous change of the voltage from the information of the divided voltage with respect to the potential fluctuation of the high voltage power supply 101 during the operation transition. . That is, the output of the voltage stabilization device 122 operates so as to be always constant. Therefore, since the high voltage at the time of rising of the load current can be made constant, a stable rising characteristic of the load current waveform is obtained, and as a result, the voltage applied to the load 104 is also stable.
[0019]
Embodiment 5. FIG.
7, when the load 104 is short-circuited or an abnormality occurs in the high-voltage power supply 101, the current value detected by the current detector 123 is detected by the current detector 123 with respect to the current flowing in the load such as the electron tube exceeding the specified value, and the control circuit 108 is informed. Send as. In the case of a current flowing through a load greater than a specified value, the control circuit 108 stops the operation of the high voltage switch 110 by a trigger signal input to the trigger terminal 109. In addition, when a single noise is mixed in the current detector, a current exceeding a specified value may temporarily flow to the control circuit 108 as an output of the current detector 123. When it becomes, it judges with the control circuit 108, and makes the high voltage switch 110 operate again. In this case, since there is no need to stop the high voltage switch 110 in the case of an instantaneous single-shot noise or the like, the ON / OFF control of the high voltage switch 110 is performed in consideration of the time factor for the current exceeding the specified value. From the above, stable operation of the pulse generator can be achieved.
[0020]
【The invention's effect】
As described above, according to Claims 1 and 2, the pulse generator of the transmitter includes the capacitor bank connected in parallel to the high-voltage power supply, and the high-voltage switch connected in series to the anode side of the high-voltage power supply. An impedance matching inductor is installed between the pulse transformers, and the high voltage switch is turned on / off based on the control signal to supply the pulse voltage to the load provided on the secondary side of the pulse transformer for impedance matching. The inductor matches the impedance of the pulse transformer and the load, and has an inductance value such that the load current supplied to the load has a flat characteristic. During the period when the load current is flat, a high-frequency signal is supplied to the load. enter since so as to generate a pulse signal, the peak value of the current flowing through the electron tube as a load becomes flat, off Tsu bets period to when the input high-frequency signal input to the electron tube can be suppressed spreading of the spectrum of the RF signal. The load has the same effect even in the case of a transmitter tube or a magnetron.
[0021]
According to the third aspect of the present invention, since the means for absorbing a part of the energy stored in the impedance matching inductor is provided, the number of series connected semiconductor switch elements used for the high voltage switch can be reduced.
[0022]
Further, according to the fourth aspect, since the RC snubber circuit is added to both terminals of the high voltage switch, the same effect as that of the third aspect can be obtained.
[0023]
According to the fifth aspect, since the diode and the resistor are added in series between both terminals of the impedance matching inductor, the fall of the load current waveform becomes steep and the spread of the spectrum of the high-frequency signal output can be suppressed.
[0024]
According to the sixth aspect, since a diode and a resistor connected in series are added in parallel between the impedance matching inductor and the primary side of the pulse transformer, the same effect as that of the third aspect can be obtained.
[0025]
According to the seventh aspect of the present invention, since the voltage stabilizing device is mounted in order to stabilize the high-voltage power supply, the high-voltage voltage at the time of rising of the load current can be made constant, so that stable rising characteristics of the load current waveform can be obtained. As a result, the voltage applied to the load is also constant.
[0026]
Further, according to claim 8, assuming that the load is short-circuited or the high-voltage power supply is abnormal, the current detector is installed on the secondary side of the pulse transformer. Since the control circuit can immediately determine and stop the high voltage switch, the high voltage switch and the electron tube can be protected. In addition, when single noise is mixed in the current detector, a current exceeding the specified value may temporarily flow to the control circuit as the output of the current detector. In such a case, the control circuit can make a determination and restart the high voltage switch. That is, ON / OFF of the high voltage switch can be controlled.
[Brief description of the drawings]
FIG. 1 is a block diagram of a pulse generator according to Embodiment 1 of the present invention.
FIG. 2 is an equivalent circuit of the pulse generator according to Embodiment 1 of the present invention.
FIG. 3 is a load current waveform diagram according to the first embodiment of the present invention.
FIG. 4 is a block diagram of a pulse generator according to Embodiment 2 of the present invention.
FIG. 5 is a load current waveform diagram according to the second embodiment of the present invention.
FIG. 6 is a block diagram of a pulse generator according to Embodiment 3 of the present invention.
FIG. 7 is a block diagram of a pulse generator according to Embodiments 4 and 5 of the present invention.
FIG. 8 is a diagram illustrating a load current waveform mounted on a conventional PFN.
FIG. 9 is an example of a spectrum diagram of high-frequency output.
[Explanation of symbols]
101 High Voltage Power Supply, 102 Capacitor Bank, 103 Pulse Transformer, 104 Load, 105 High Frequency Signal Input Terminal (RF IN), 106 High Frequency Signal Output Terminal (RF OUT), 107 Amplifier, 108 Control Circuit, 109 Trigger Terminal, 110 High Voltage Switch , 111 capacitors, 112 resistors, 113 impedance matching inductors, 115 diodes, 116 resistors, 120 voltage detection resistors, 121 voltage detection resistors, 122 voltage stabilizers, 123 current detectors, 124 control terminals

Claims (8)

A capacitor bank connected in parallel to the high voltage power supply;
A high voltage switch connected in series from the anode side of the high-voltage power source, an impedance matching inductor, and a pulse transformer,
Supplying a pulse voltage to a load provided on the secondary side of the pulse transformer by operating the high voltage switch on / off based on a control signal,
The impedance matching inductor has an inductance value that matches impedance with the pulse transformer and the load, and has a flat characteristic of a load current supplied to the load,
A pulse generating apparatus , wherein a pulse signal is generated by inputting a high frequency signal to the load during a period when the load current is flat . The inductance value of the impedance matching inductor is
The inductance value of the impedance matching inductor is L1, the leakage inductance value of the pulse transformer is L2, the combined capacitance of the pulse transformer and the stray capacitance generated between the cathode of the load and GND, and the primary side of the load impedance When the converted value is R,
(L1 + L2) = 4CR ²
The pulse generator according to claim 1, wherein:   3. The pulse generator according to claim 1, further comprising means for absorbing energy stored in the impedance matching inductor.   The pulse generator according to claim 3, wherein an RC circuit in which a resistor and a capacitor are connected in series is mounted on both ends of the high-voltage switch.   4. The pulse generator according to claim 3, wherein a diode for absorbing energy stored in the impedance matching inductor and a resistor are connected in parallel to the impedance matching inductor.   4. The pulse generator according to claim 3, wherein a diode and a resistor for absorbing energy stored in the impedance matching inductor are connected in parallel to a series circuit of the impedance matching inductor and a pulse transformer.   Adding a voltage stabilizing device between the high voltage power supply and the high voltage switch, sending the output voltage of the voltage stabilizing device to the voltage stabilizing device as a monitor signal, and stabilizing the output of the voltage stabilizing device; The pulse generator according to any one of claims 1 to 6, characterized in that:   The pulse generator according to any one of claims 1 to 7, wherein the high voltage switch is controlled based on an output from a current detector installed on a secondary side of the pulse transformer.

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