JP3477351B2 - Thyratron drive circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thyratron drive for driving a thyratron used as a switch of a resonance circuit incorporated in, for example, a pulse generator for an electrostatic precipitator. Circuit. 2. Description of the Related Art Conventionally, an electrostatic precipitator (hereinafter referred to as EP) has been known.
As shown in FIG. 3, a resonance circuit using a thyratron as a switch is incorporated in the pulse generator for use in the present invention. In this example, a capacitor 22 is connected to a DC power supply 21, and a thyratron 24 is connected in parallel to the capacitor 22 via an inductance element 23 and an impedance element 27.
4, a reverse current bypass circuit 25 is connected in anti-parallel, and the capacitor 22, the inductance element 23, the impedance element 27, the thyratron 24 and the reverse current bypass circuit 25 form a resonance circuit. However, the inductance element 23 is mainly an inductance component on a wiring, and the impedance element 27 is mainly a wiring and an E component.
This is due to the impedance component caused by the discharge in P. A heater power supply 30 for improving the electrical characteristics of the thyratron 24 is connected to the thyratron 24. The thyratron 24 is turned on by a pulse generation circuit 26 and an off-bias circuit 28 controlled by a timing control circuit 29. / Off and used as a switch of the resonance circuit. More specifically, as shown in the timing chart of FIG.
When charging 2 (time t = 0 to t ₁ ), an off-bias voltage is supplied to the grid of the thyratron 24 by the off-bias circuit 28, and the off-state of the thyratron 24 is maintained. After the electric charge is accumulated in the capacitor 22, the pulse generation circuit 26
When a one-shot comb-shaped pulse voltage is supplied to the grid of the thyratron 24 (time t = t ₁ ), the internal gas of the thyratron 24 is discharged and the thyratron 24 is turned on. As a result, a resonance circuit is formed by the capacitor 22, the inductance element 23, the impedance element 27, and the thyratron 24, and the charge stored in the capacitor 22 starts to flow as a resonance current. When a negative voltage is applied to the anode (plate) of the thyratron 24 (time t = t ₂ ) due to the resonance phenomenon of the resonance circuit, the thyratron 24 self-extinguishes and turns off, and then the forward current Until starts flowing (time t = t ₃ ), an off-bias voltage is supplied by the off-bias circuit 28 to prevent erroneous firing. During this time (time t = t _{2 to} t ₃ ), the resonance current of the resonance circuit flows through the reverse current bypass circuit 25. Hereinafter, at times t = t ₃ , t ₅ , t ₇ ,..., A comb-shaped pulse voltage is supplied to the grid of the thyratron 24, and at other times, an off-bias voltage is supplied. The thyratron 24 is similarly driven until the flow is attenuated and no longer flows. On the other hand, as shown in the timing chart of FIG. 5, after the capacitor 22 is charged (t = t
₁ ) The discharge state of the thyratron 24 is changed by continuously supplying a long pulse voltage (on-bias voltage) to the grid of the thyratron 24 for a preset on-hold time (t = t _{1 to} t ₉ ). There is also a method of maintaining the ON state of the thyratron 24 until the resonance current of the resonance circuit attenuates and stops flowing. As described above, conventionally, when a thyratron is used as a switch in a resonance circuit, a comb-shaped pulse voltage is supplied to the grid of the thyratron in accordance with the resonance period, The method of continuously supplying the pulse voltage for a predetermined time has been adopted. However, when a comb-shaped pulse voltage is supplied, it is necessary to predict the timing at which a forward resonance current flows through the thyratron from the resonance period of the LCR resonance circuit, and to set the pulse voltage supply timing. However, there is a problem that the timing control is very difficult because the voltage varies depending on the circuit and surrounding conditions. In addition, since a high-voltage pulse is supplied every time a forward resonance current flows, there is a problem that the loss increases. On the other hand, when a long pulse voltage is continuously supplied, no matter how much current flows in the thyratron grid once turned on, the supplied energy is consumed as a large amount of reactive energy and the efficiency is reduced. Drop,
In addition, there is a problem that the size of the device itself becomes large. The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a thyratron driving circuit which is easy to control and has high efficiency. [0013] In order to solve the above-mentioned problems, the present invention is directed to a battery which is charged by an output from a DC power supply.
Inductance element and impedance in the discharge path of
Thyratron via a dance element and the thyratron
Connect a reverse current bypass circuit connected in anti-parallel to
These capacitors, inductance elements, impedance
Components, thyratrons and reverse current bypass circuits
Generates a pulse voltage to excite the thyratron to the ON state in the thyratron drive circuit that forms the oscillation circuit
A pulse generating circuit for supplying to the thyratron in the previous
ON state of the thyratron by supplying the pulse voltage
In order to maintain the pulse voltage, the pulse voltage generation circuit
An on-bias circuit for supplying an on-bias voltage lower than the pulse voltage to the thyratron, and an off-bias circuit for supplying an off-bias voltage for returning the thyratron from the on state to the off state to the thyratron after generating the pulse voltage. It is characterized by having. FIG. 1 is a diagram showing a configuration of a thyratron drive circuit according to one embodiment of the present invention. This circuit is incorporated in a pulse generator for an electrostatic precipitator, and the thyratron 4 forms an LCR resonance circuit together with the capacitor 2, the inductance element 3, the impedance element 11, and the reverse current bypass circuit 5. That is, a capacitor 2 is connected to the DC power supply 1. One end of the capacitor 2 is connected to the anode (plate) of the thyratron 2 via the inductance element 3 and the impedance element 11, and the other end is connected to the thyratron 2. Connected to the cathode. The inductance element 3 is mainly due to an inductance component on the wiring, and the impedance element 11 is mainly due to an impedance component caused by a discharge in the wiring and the EP. A reverse current bypass circuit 5 is connected in parallel to the anode and the cathode of the thyratron 4. The reverse current bypass circuit 5 is formed by a diode, a thyratron, or the like, and is connected to the thyratron 5 in antiparallel. A thyratron drive circuit for driving the thyratron 4 is formed by a pulse generation circuit 6, an on-bias circuit 7, an off-bias circuit 8, a timing control circuit 9, and a heater power supply 10. The pulse generating circuit 6 is for exciting the thyratron 4 to an off state. The on-bias circuit 7 is for continuously supplying energy (on-bias voltage) to the thyratron 4 in order to maintain the thyratron 4 in the on state while maintaining the discharge state. The off-bias circuit 8 is used to hold the off-state of the thyratron 4 to prevent erroneous firing. The timing control circuit 9 includes a pulse generation circuit 6, an on-bias circuit 7,
And for controlling the operation timing of the off-bias circuit 8. The heater power supply 10 is used as a power supply for a heater circuit (not shown) for improving the electrical characteristics of the thyratron 4. The operation of the circuit shown in FIG. 1 will be described below with reference to the timing chart shown in FIG. FIG.
In (a), the voltage across the thyratron 4 (anode-cathode voltage), (b) the anode current (resonant current) of the thyratron 4, (c) the output voltage (grid voltage) of the thyratron drive circuit, (d) ) Represents the output current (grid current) of the thyratron drive circuit. [0021] First, at time t = 0 to t _1, capacitor 2 is charged by the DC power supply device 1. At this time, the off bias circuit 8 supplies a negative off bias voltage to the grid of the thyratron 4 so that the off state of the thyratron 4 is maintained. In this example, the timing control circuit 9 starts the off-bias circuit 8 at time t = 0 and stops it at time t = t _1. However, the off-bias voltage is temporarily changed to the pulse voltage by the pulse generation circuit 9 and the on-bias voltage. If the on-bias voltage is set smaller than the on-bias voltage by the circuit 7, the off-bias circuit 8 may be activated once and the off-bias voltage may be continuously supplied without stopping the operation. At time t = t ₁ , charging of the capacitor 2 ends, and a command signal of the timing control circuit 9 is supplied to the pulse generation circuit 6. The pulse generation circuit 6 supplies a one-shot pulse voltage having a sharp rise to the grid of the thyratron 4 in response to the command signal. The internal gas of the thyratron 4 is discharged by the pulse voltage from the pulse generation circuit 6 to be turned on. As a result, the capacitor 2, the inductance element 3,
An LCR resonance circuit is formed by the impedance element 11 and the thyratron 4, and the electric charge stored in the capacitor 2 starts flowing as a resonance current. The timing control circuit 9 operates until the pulse generator 6 turns the thyratron 4 on.
Another command signal is output to the on-bias circuit 7. The on-bias circuit 7 operates in response to the command signal.
Start supplying the on-bias voltage to the grids. The on-bias voltage may be a minimum required voltage value lower than the pulse voltage, which is a degree that the on state of the thyratron 4 is maintained, that is, a degree that the discharge state of the thyratron 4 is maintained, and actually differs for each thyratron. Value. Also,
The time to keep supplying the on-bias voltage (ON maintenance time)
Is set based on the time when the resonance current of the LCR resonance circuit attenuates and stops flowing (time t = t _{1 to} t ₉ ). Due to the resonance phenomenon of the LCR resonance circuit, a forward resonance current flows through the thyratron 4 between times t = t _{1 and} t ₂ (first forward current). When the first forward current ends flowing through the thyratron 4, the subsequent time t =
Between t _{2 and} t ₃ , a resonance current flows in the LCR resonance circuit in the opposite direction to the thyratron 4. At this time, the resonance current is flowing through the reverse current bypass circuit 5. However, even in this state, the thyratron 4
, The on state of the thyratron 4 is maintained. At time t = t ₃ , a forward resonance current starts flowing through the LCR resonance circuit to the thyratron again (second forward current). In this case, the on-state of the thyratron 4 is maintained by the on-bias circuit 7, so that the resonance current starts flowing through the thyratron 4 immediately. Similarly, the resonance current of the LCR resonance circuit flows through the thyratron 4 between times t = t _{3 to} t ₄ , t _{5 to} t ₆ , t _{7 to} t ₈ ,. t _{4 to} t
_5, t ₆ ~t _7, ... during the flow through the reverse current bypass circuit 5. Then, the resonance current of the LCR resonance circuit gradually decreases due to resistance components in the circuit including the impedance element 11. After the resonance current stops flowing through the LCR resonance circuit, the supply of the on-bias voltage by the on-bias circuit 7 is stopped at time t = t ₉ . Thereafter, the off-bias circuit 8 supplies the off-bias voltage to the grid of the thyratron, thereby preventing the thyratron 4 from being erroneously fired. As described above, according to the thyratron driving circuit of the present embodiment, after the pulse voltage is first supplied from the pulse generation circuit 6 to turn on the thyratron 4, the thyratron 4 is lower than the pulse voltage. The ON state of the thyratron 4 can be maintained only by continuing to supply the ON bias voltage to the ON bias circuit 7 such that the discharge state is maintained. In this case, when the resonance current flowing through the LCR resonance circuit becomes a forward current with respect to the thyratron 4, the current starts flowing through the thyratron 4 immediately. That is,
Unlike the conventional method of supplying a pulse voltage to the thyratron 4 in synchronization with the resonance cycle, the thyratron 4 can be driven without complicated timing control and a forward current can be continuously supplied. In addition, since the life of the thyratron 4 is generally defined by the number of transitions from the off state to the on state, deterioration of the thyratron 4 can be reduced by maintaining the on state. Further, once the thyratron 4 is excited to an ON state, the discharge of the thyratron 4 is maintained by an ON bias circuit for supplying an ON bias voltage lower than the pulse voltage generated by the pulse generating circuit 6 thereafter. Since only the minimum necessary energy needs to be supplied, the thyratron can be driven with high efficiency, unlike the conventional method of continuously supplying a long pulse voltage. In addition, since the size of components such as a transformer is small, the size of the device itself is reduced, and the cost is reduced. As described above, according to the present invention, after the pulse voltage is supplied to the thyratron to excite the thyratron to the on state, only the supply of the on-bias voltage lower than the pulse voltage is continued. To maintain the ON state. Therefore, when the thyratron is used as a switch of the resonance circuit, a forward current can be continuously passed through the thyratron without performing complicated timing control. Also, only the pulse voltage required to excite the thyratron to the on state needs to be high, and the on-bias voltage for maintaining the on state is the minimum energy required to maintain the discharge of the thyratron. Therefore, the thyratron can be driven with high efficiency.

Figure 2 shows a timing chart [diagram for explaining an operation of the embodiment showing a structure of a thyratron drive <br/> circuits according to an embodiment of the BRIEF DESCRIPTION OF THE DRAWINGS [Figure 1] The present invention 3 is a diagram showing an example of a conventional thyratron drive circuit. FIG. 4 is a timing chart for explaining the operation of the conventional thyratron drive circuit. FIG. 5 is a timing chart for explaining the operation of the conventional thyratron drive circuit. Description 1 DC power supply device 2 Capacitor 3 Inductance element 4 Thyratron 5 Reverse current bypass circuit 6 Pulse generation circuit 7 On bias circuit 8 Off bias circuit 9 Timing control circuit 10 Heater power supply 11 Impedance element

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-80122 (JP, A) JP-A-9-135566 (JP, A) JP-A 4-23330 (JP, U) JP-A 60-80 136545 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H02M 1/00-1/30

Claims (1)

(57) [Claim 1] Charged by an output from a DC power supply
Inductance element and impedance in the discharge path of
Thyratron via a dance element and the thyratron
Connect a reverse current bypass circuit connected in anti-parallel to
These capacitors, inductance elements, impedance
Components, thyratrons and reverse current bypass circuits
In thyratron drive circuit forming the oscillator circuit, a pulse generating circuit for supplying to the thyratrons generates a pulse voltage for exciting the thyratron in the ON state, on the form of the thyratron by the supply of the pulse voltage
In order to maintain the state, the pulse voltage generation circuit
An on-bias circuit for supplying an on-bias voltage lower than the pulse voltage to the thyratron after generating a pulse voltage ; and an off-bias circuit for supplying an off-bias voltage for returning the thyratron from an on state to an off state to the thyratron. A thyratron drive circuit, comprising: