JPH0161219B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a DC high voltage power supply using a stacking method used in large power amplification devices such as traveling wave tubes and klystrons, and in particular suppresses transient voltage that occurs between the collector body when the power is turned on. This invention relates to a DC high voltage power supply equipped with an overvoltage protection circuit.

A stacked DC high voltage power supply is a power supply device that mainly consists of a collector power supply, a filter consisting of a resistor and a capacitor to improve the output ripple of this power supply, and a body power supply connected between the resistor and the capacitor. In contrast to the body power output terminal which is normally grounded, the collector power output terminal is negative by the amount of the body power output voltage. And the rise speed of the collector power supply is usually 50
The rise speed of the body power supply is usually about 100ms or larger, and the time constant of the filter is usually about the same as or around the same as the rise speed of the collector power supply. Therefore, if you turn on the power to such a power supply without implementing an overvoltage prevention mechanism, as will be explained in detail later, a rising transient voltage will occur across the above resistor, and this rising transient voltage and the voltage at that point will be A difference in the output voltage of the body power supply is applied between the collector and the body with a polarity opposite to the normal potential.
This reverse polarity voltage reaches nearly half of the collector power supply output voltage even in the normal usage described above, and the time constant of the filter must be increased to reduce ripple, or the collector power supply output voltage must be increased to obtain a high voltage in a short time. If the rise speed is reduced, almost the entire voltage of the collector power supply will be applied, exceeding the withstand voltage between the collector and body of the load tube. This phenomenon occurs when the collector power supply is turned on before the body power supply in the power supply order.
This is even more noticeable when the so-called collector potential depression (CPD) is shallow, in which the accumulated body voltage is set low and the collector voltage is set high.

For the reasons mentioned above, in conventional high-voltage DC power supplies of this type, overvoltage has been prevented by slowing down the rise speed of the collector power supply or increasing it in steps. However, this measure has the disadvantage that the power supply takes a long time to start up and requires a control circuit to control power-on.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a stacked type DC high voltage power supply that does not slow down the rise of the power supply voltage, has a simple structure, and is provided with an inexpensive overvoltage protection circuit.

According to the present invention, a collector power supply, a filter consisting of a first resistance element and a first capacitor for improving ripple in the output of the collector power supply, and a filter connected between the first resistance element and the capacitor are provided. In the DC high voltage power supply, the DC high voltage power supply has a stacking body power supply and generates two desired DC high voltages with respect to a reference voltage, between the output terminal of the collector power supply and the output terminal of the body power supply,
A series circuit of a second resistive element and a diode facing from the output terminal of the collector power supply to the output terminal of the body power supply is provided, and a series circuit is provided between the output terminal of the body power supply and the reference voltage terminal of the collector power supply. , a second capacitor is provided which, in combination with the second resistance element, forms a series circuit having a time constant smaller than the time constant of the filter, so that when the power is turned on, the output terminal of the collector power supply is connected to the second capacitor. A DC high-voltage power supply using a stacking method is obtained, which is characterized by suppressing overvoltage generated between the output terminals of the body power supply.

Next, a detailed description will be given with reference to the drawings.

The figure shows the configuration of an embodiment of the present invention. 1 is a collector power supply with an output voltage of, for example, 17 kV and a relatively fast rise speed of about 50 ms, and 2 is a body with an output voltage of 4 wV and a rise speed of about 150 ms. In the power supply, 3 is a 33 kΩ resistor, 4 is a 1 μF capacitor, and the resistor 3 and capacitor 4 constitute a ripple cancellation filter with a time constant of 33 ms. The elements up to this point constitute the main body of the stacked DC high voltage power supply.

Next, 5 is a 5kΩ resistor, 6 is a 0.5μF capacitor, and 7 is a diode, and these elements 5, 6,
7 forms an overvoltage protection circuit in the high voltage power supply of the present invention. The time constant due to the resistor 5 and capacitor 6 is approximately 2.5 ms, and the time constant due to the resistor 3 and capacitor 4 that constitutes the filter is 33 ms.
It is set much smaller. Diode 7 is
When the collector power supply 1 is turned on, the transient voltage is forward biased to make the resistor 5 and capacitor 6 of the overvoltage protection circuit conductive, and in the steady state after the power is turned on, the body voltage is reverse biased to make the resistor 5 and capacitor 6 conductive. This is to make it non-conductive. Also, A is the output terminal of the collector power supply 1,
B is the grounded output terminal of the body power supply 2, P is the output terminal of the ripple improvement filters 3 and 4, and Q
is a common reference voltage output terminal of the power supplies 1 and 2 stacked together, and the potentials of terminals A, B, and P are measured with terminal Q as a reference.

If both power supplies 1 and 2 are turned on at the same time in this state, a transient voltage of the collector power supply will be generated between both terminals AP of the resistor 3 with the terminal A side being positive, and at the same time a transient voltage of the body power supply will be generated between the terminals BP. is also generated with the ground terminal B side as positive polarity. Since these two transient voltages are connected in series with opposite polarities at the filter output terminal P, if an overvoltage protection circuit described later is not provided, both the above-mentioned transient voltages will be connected between the terminals A and B. A voltage corresponding to the difference between is generated, and in this case, the transient voltage of the collector power supply 1 becomes a large value close to half of its output voltage, and at this point the output voltage of the body power supply 2 has not increased slightly. , a very large positive voltage is applied to the collector output terminal A with respect to the ground terminal B, which exceeds the withstand voltage between the collector and the body.

However, in the present invention, both terminals A and B
Since an overvoltage protection circuit consisting of a resistor 5, a diode 7, and a capacitor 6 is provided in between, the capacitor 6 is charged extremely quickly through the resistor 5 and diode 7 as soon as the collector power supply 1 is turned on, and the ground terminal B is brought to the reference potential. The potential of the filter output terminal P changes to the negative side with respect to the ground terminal B by the charging voltage of the capacitor 6, and therefore both terminals The transient voltage generated between the terminals B and P apparently increases by that amount. On the other hand, the transient voltage generated between both terminals A and P does not change before and after adding the above-mentioned overvoltage protection circuit. Therefore, the transient voltage generated between terminals A and B is reduced.

The above explanation can be expressed numerically as follows. That is, the transient voltage between both terminals A and P is E _A ,
The transient voltage between both terminals B and P is E _B , and the resistor 5
If the charging voltage of capacitor 6 is ΔE _C , then
By providing the above-mentioned overvoltage protection circuit, the transient voltage generated between both terminals A and B can be reduced from conventional E _A -
E _B (described above) becomes E _A −(E _B +ΔE _C ), and it becomes possible to suppress by ΔE _C. However, during this transition period, when the voltage at terminal A becomes higher than the voltage at terminal B, the value of charging voltage ΔE _C of capacitor 6 becomes equal to the voltage output from collector power supply 1 (voltage
Since it follows E (greater than _A ) in a short time, the transient voltage
E _A −(E _B +ΔE _C ) can be made close to zero.

In the above embodiment, the resistor 5 and capacitor 6
The ratio of the time constant of and that of resistor 3 and capacitor 4 is
We have shown an example of reducing the transient voltage between terminals A and B to 1/10 or less, but in reality the transient voltage may be up to the withstand voltage of the electron tube, so the above ratio is not so small. It is not necessary to do this, and depending on other conditions, it may be possible to use even just one.
The other conditions mentioned above are, for example, when the body power is turned on before the collector power, in which case the above ratio can be relatively large, and conversely, after the collector power is turned on, If body power is applied, the above ratio should be relatively small, and the CPD mentioned earlier
In the case of a shallow operation, it is necessary to keep the above ratio as small as in the previous embodiment.

In the above-described embodiment, resistors 3 and 5 are used to determine the time constant, but instead of these, a coil may be used as the resistor during the transition period, or both may be used. Therefore, in this specification, the expression "resistance element" is used to represent both. Further, in a conventional DC high voltage power supply, a capacitor 6 is sometimes provided in order to stabilize the output of the body power supply 2, but the capacitance is only necessary for output stabilization, and the present invention As such, there is essentially no relationship between the resistive elements 3 and 5 and the capacitor 4 that determine the capacitance value.

As detailed above, the high-voltage power supply equipped with the overvoltage protection circuit according to the present invention can be used in high-power amplification devices that require high startup speed after power outage recovery, such as traveling wave tubes and klystrons for satellite communications earth stations. Even when used as a high-voltage power supply for a large power amplifier, etc., an overvoltage exceeding the reverse breakdown voltage does not occur between the collector body, and it has the advantage of not requiring a special control circuit.

[Brief explanation of drawings]

The figure is a diagram showing a circuit configuration of a DC high-voltage power supply using a stacking method, which is an embodiment of the present invention. Explanation of symbols: 1 is the collector power supply, 2 is the body power supply for stacking, 3 is the resistor, 4 is the capacitor, 5 is the resistor, 6 is the capacitor, 7 is the diode, A is the output terminal of the collector power supply, B is the output of the body power supply Terminal P represents a filter output terminal, and Q represents a reference voltage terminal, respectively.

Claims (1)

[Claims] 1 a collector power supply, a filter consisting of a first resistive element and a first capacitor for improving ripple in the output of the collector power supply, and the first
It has a body power supply for stacking connected between the resistive element and the capacitor, and has a desired voltage of 2 with respect to the reference voltage.
In the DC high-voltage power supply that generates two DC high voltages, a second resistance element is provided between the output terminal of the collector power supply and the output terminal of the body power supply, and a second resistance element is connected between the output terminal of the collector power supply and the body power supply. A series circuit with a diode facing the output terminal of the body power supply and a reference voltage terminal of the collector power supply is provided between the output terminal of the body power supply and the reference voltage terminal of the collector power supply.
A second capacitor is provided which forms a series circuit having a time constant smaller than the time constant of the filter in combination with the resistive element of the filter, thereby connecting the output terminal of the collector power supply and the body power supply when the power is turned on. A DC high-voltage power supply using a stacking method that suppresses overvoltage that occurs between output terminals.