JPS5838794Y2 - Kouatsuchiyokuriyudengensouchi - Google Patents

Description

[Detailed description of the invention] This invention relates to a high-voltage DC power supply, and more specifically, a high-frequency input is added to the primary side of a transformer, a multi-stage voltage doubler rectifier circuit is connected to the secondary side, and the output is smoothed by a smoothing circuit. The present invention relates to a high-voltage DC power supply device that can be taken out through a power supply.

FIG. 1 shows a conventional circuit of such a power supply device.

In other words, on the primary side of the transformer T, a high frequency voltage on the order of KHz is usually excited by an oscillation circuit, and on the secondary side, a multi-stage voltage doubler rectifier circuit is connected to output the high voltage AC output induced on the secondary side. Multi-stage voltage doubler rectification is performed, and the output is connected to resistors R1, R2...Ro and capacitor C1.
, C2, . . . , through a smoothing circuit consisting of co.

In the figure, Cf1. Cf2...Cf is a stray capacitance between the input end and the output side of the voltage doubler rectifier circuit.

In such a circuit, the ripple voltage appearing at the output is determined not only by the time constant of the CR of the smoothing circuit, but also by the capacitances C1, C2, etc. of each of the smoothing circuits.
. . Cn and stray capacitance Cf1. Cf2...Cf
A voltage component obtained by dividing the input voltage of the multi-stage voltage doubler rectifier circuit is added depending on the ratio with o.

For example, considering the point of the smoothing capacitor C3 on the output side of the multi-stage voltage doubler rectifier circuit, the stray capacitance between that point and the input side of the multi-stage voltage doubler rectifier circuit is Cf2. The voltage on the input side of the multistage voltage doubler rectifier circuit is υ.

Then, at the point of the smoothing capacitor C3, a voltage of the magnitude represented by is applied as a ripple voltage.

Then, at the output end from which the high DC voltage is taken out, a ripple voltage having the total magnitude of the ripple voltages generated at each point appears.

Furthermore, as the input frequency increases, the impedance of the stray capacitance decreases, so the alternating current component appearing on the output side increases and the ripple voltage becomes even larger.

Therefore, in order to reduce this ripple voltage, the stray capacitance Cf1.
Conventionally, countermeasures such as these have been taken because it is sufficient to reduce Cf2...Cfo or increase the capacitances C1, C2...co of the smoothing circuit. This was in opposition to the miniaturization and cost reduction of the technology.

For reference, point a and point b in Figure 1. The voltage waveforms at point 0 and point d are shown in Figure 2 a, l), c, and d, respectively.

This invention eliminates the drawbacks of the conventional device and realizes miniaturization and cost reduction, and furthermore, it can stably reduce ripple voltage even when the output voltage is on the order of several KV to several tens of KV. The purpose of this device is to provide a high-voltage DC power supply that can divide the primary voltage using a series-connected circuit of multiple capacitors, and multiply the secondary voltage, which has the opposite phase to this divided voltage, in multiple stages. Add the divided voltage on the negative side to the ground side of the smoothing capacitor of the smoothing circuit connected to this multi-stage voltage doubler rectifier circuit, and connect the connection point of the capacitor to take out this divided voltage. The gist of this is that it is grounded via a resistor.

An embodiment of this invention will be described in detail below with reference to the drawings.

In FIG. 3, the same parts as in FIG. 1 are given the same reference numerals, and their explanation will be omitted.

In other words, there are two points that differ from the one in FIG.

The first is that the polarity of the secondary side of the high voltage transformer T is reversed compared to the conventional one, and the second is that capacitors Ca and Cb connected in series are provided in place of the resonant capacitor C8 of the oscillation circuit on the primary side. The connection point of these capacitors Ca and Cb is connected to the ground side of smoothing capacitor C3 of the smoothing circuit, and the connection point of capacitors Ca and Cb is connected to a resistor Ra (
This means that it is grounded through a metal (usually several Mg).

In the high-voltage DC power supply device configured in this way, a voltage corresponding to the turns ratio of the transformer T of a high-frequency voltage of KHz order excited on the primary side by the oscillation circuit is induced on the secondary side, and this voltage is converted into a multi-stage voltage doubler. The rectifier circuit performs multi-stage voltage doubler rectification and applies it to the smoothing circuit, and the high DC voltage is taken out from the output terminal. However, the ripple voltage caused by the presence of stray capacitance is the divided voltage by the capacitor on the primary side of the transformer T. The ripple content in the output will be extremely small.

In other words, the voltage waveforms at points e, f, and g in FIG.
As shown in figures a, l) and c, respectively, the capacitor C
Since the voltage obtained from the connection point of a and Cb is in the opposite phase to the ripple voltage which is in phase with the voltage at point f, an appropriate voltage is applied to the primary side capacitor Ca,
By applying it to the ground side of the smoothing capacitor from the connection point of Cb, the ripple voltage is canceled out.

In other words, the appropriate voltage obtained from the connection point of capacitors Ca and Cb is the total magnitude of the ripple voltage generated at each point on the output side of the multi-stage voltage doubler rectifier circuit, which occurs at the output end from which high DC voltage is taken out. The voltage is large enough to cancel out the ripple voltage.

It should be noted that a resistor Ra connected to the connection point of the capacitors Ca and Cb allows DC leakage current of the smoothing capacitor C3 to flow.

Further, the smoothing capacitor that applies the voltage obtained from the connection point of the capacitors Ca and Cb is not limited to the capacitor C3 as in the above embodiment, but may include capacitors 01 to 01.
It will be easily understood from the above description that any of co may be used.

In other words, the magnitude of the voltage to cancel the ripple voltage that appears in the output due to the presence of stray capacitance is determined by how many stages of capacitors in the smoothing circuit it is applied to, and the capacitance ratio of the primary side capacitors Ca and Cb is All you have to do is change it to get it.

In addition, the primary side capacitor Ca. In addition to the connection shown in FIG. 3, the connection of cb may be as shown in FIGS. 5 and 6, for example.

The one shown in FIG. 5 is connected to both ends of the primary winding of the transformer T, and the one shown in FIG. 6 is connected to both ends of the primary winding further wound.

Furthermore, the capacitors Ca and Cb may be separate from the resonant capacitance of the primary side oscillation circuit.

As explained above, the high-voltage DC power supply device of this invention divides the voltage on the primary side of the transformer using a series-connected circuit of multiple capacitors, and the secondary side voltage, which is in opposite phase to this divided voltage, is multi-stage multiplied. Since the voltage is applied to the voltage rectifier circuit and the divided voltage on the negative side is applied to the ground side of the smoothing capacitor, the following effects can be obtained.

■The device can be made smaller because there is no need to innovate the structure, such as increasing the distance between the input and output sides of the multi-stage voltage doubler rectifier circuit to reduce stray capacitance.

■The capacity of the smoothing capacitor can be reduced, making it possible to make the device smaller and cheaper.

(2) Since the resistance of the smoothing circuit can be reduced, the voltage drop can be reduced, and the device can be made smaller and cheaper.

■If you set the capacitance of the multiple capacitors that take out the divided voltage to cancel the ripple voltage to be larger than the capacity of the smoothing capacitor to which the divided voltage is applied, you can turn on the power switch, etc. Even when the voltage is off or there is a ground fault on the high voltage side, only the divided voltage determined by the relationship between the combined capacitance of these multiple capacitors and the smoothing capacitor capacity is applied to the multiple capacitors that take out the divided voltage. , it is possible to realize a high-voltage DC power supply with a small ripple voltage and an output voltage on the order of several KV to several tens of KV without increasing the size of the device.

■To achieve these effects, only a slight increase in the number of parts is required.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of a conventional high-voltage DC power supply, Figure 2a,
l), c, and d are diagrams showing voltage waveforms at points a, b, C, and d in Figure 1, Figure 3 is a circuit diagram of a high-voltage DC power supply device according to an embodiment of this invention, and Figure 4 a. , l), c are e, f in Fig. 3.
, FIG. 5, and FIG. 6 are circuit diagrams showing only the primary side portion of a transformer according to another embodiment of this invention. T is a high voltage transformer, Cf1. Cf2...Cfn
are stray capacitances, R1, R2...Rn are resistances of the smoothing circuit, C, C2...Cn are capacitors of the smoothing circuit, Ca and Cb are capacitors that divide the voltage on the primary side. be.

Claims (1)

[Scope of utility model registration request] In a high-voltage DC power supply device in which a high frequency input is applied to the primary side of a transformer, a multi-stage voltage doubler rectifier circuit is connected to the secondary side, and the output is taken out via a smoothing circuit, the primary side voltage is connected to multiple capacitors. The voltage is divided by a series-connected circuit, and a secondary voltage having an opposite phase to this divided voltage is applied to a multi-stage voltage doubler rectifier circuit, and the smoothing capacitor of the smoothing circuit connected to this multi-stage voltage doubler rectifier circuit is divided. A high-voltage DC power supply device characterized in that the divided voltage of the negative side is applied to the ground side, and a connection point of a capacitor from which the divided voltage is taken out is grounded via a resistor.