JPH07222446A - High-voltage dc generation apparatus - Google Patents

Abstract

PURPOSE:To obtain the high-voltage DC generation apparatus whose polarity inverting time can be shortened by a method wherein two sets of rectifiers each of which is constitued by connecting either a resistance or a reactance or both of them in series with a diode and whose rectification direction is different from each other are installed, the rectification direction of the rectifiers is changed over and their polarity is inverted. CONSTITUTION:In a voltage-doubler rectifying circuit which is provided with capacitors C1, C2, each of rectifiers RF1, RF2 is constituted in such a way that either a resistance (r) or a reactance (l) or both of them are connected in series with a diode (d). Their rectification direction is inverted, and their polarity is inverted. Thereby, a circuit impedance is raised in the electric discharge of the capacitor C2, and a discharging current can be suppressed. Consequently, it is possible to obtain a high-voltage DC generation apparatus in which a shortcircuit overcurrent does not flow in a circuit being charged even when the rectification direction of the rectifiers RF1, RF2 is inverted and changed over, whose polarity inverting time can be made extremely short and whose polarity can be inverted safely and surely.

Description

Detailed Description of the Invention

[0001]

[Field of Industrial Application] The present invention relates to the use of DC high voltage in the field of electric power and a DC high voltage generator for academic research and development.

[0002]

2. Description of the Related Art In a DC withstanding voltage test of power equipment,
A test that reverses the charging polarity in a short time is required. 2 is an explanatory diagram of polarity inversion in the voltage doubler rectifier circuit.
(A) shows the connection state before polarity reversal, and the diode D1
A positive voltage can be generated from the connection direction of D2 and D2.

FIG. 2B shows the connection state of the diodes D1 and D2 when the polarity of the diodes D1 and D2 is reversed by reversing the connection direction of the diodes D1 and D2. From the connection state of FIG. 2A to FIG. When switching to the connection state of
The charged electric charge of 2 is short-circuited and discharged to the diodes D1 and D2, and an excessive discharge current flows through the diodes D1 and D2, and the diodes D1 and D2 are instantly destroyed.

The circuit shown in FIG. 3 has conventionally been generally used to protect the diode from the excessive discharge current. That is, in FIG. 3, when the polarity reversal command is given, the power switch S1 is opened, the discharge switches S2 and S3 are turned on, and the charges charged in the capacitors C1 and C2 are discharged to the discharge resistors R1 and R2. And D2, the polarity of the changeover switch S is inverted, the discharge switches S2 and S3 are opened, and the power switch S1 is turned on to complete the polarity inversion.

According to the above method, it takes a long time to operate each switch and discharge and charge the capacitor, and the polarity reversal requires at least several tens of seconds. The polarity reversal time of the rectifier circuit is the time from when the output voltage of the DC high voltage generator starts to decrease until the voltage of the inversion polarity reaches the voltage value before the inversion.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to realize a DC high voltage generator having a polarity reversal time of at least 1 second (the unit is hereinafter referred to as s).

[0007]

SUMMARY OF THE INVENTION According to the present invention, two sets of rectifiers having different rectification directions, each of which has a diode or a resistor or a reactance connected in series, are provided, and the rectification direction of the rectifier is switched. And a DC high voltage generator having a voltage doubler rectifier circuit capable of inverting the polarity.

That is, (1) In a voltage doubler rectifier circuit consisting of two diodes D1 and D2 connected to an AC power source e and two capacitors C1 and C2, one of a resistor r and a reactance l is added to a diode d or A direct current high voltage generator characterized in that the rectifiers RF1 and RF2, which are configured by connecting both in series, invert the rectifying direction and invert the polarity. (2) The DC high voltage generator according to (1) above, characterized in that a voltage doubler rectifier circuit comprising rectifiers RF1 and RF2 and capacitors C1 and C2 is connected in multiple stages in series.

[0009]

A double voltage rectifier circuit comprising diodes D1 and D2 and capacitors C1 and C2. In FIG. 2A, if the polarity of diodes D1 and D2 is reversed in a circuit having a capacitor in a charged state, especially C2, capacitor C2
The short circuit discharges the charge of the diode D1 and D2 to destroy the diodes D1 and D2.

If the diodes D1 and D2 are replaced by rectifiers RF1 and RF2 in which one or both of a resistor r and a reactance l are connected in series to the diode d as in the circuit shown in FIG. 1, then the capacitor C2 is discharged. The circuit impedance rises and the discharge current can be suppressed, and this can be protected without causing an overcurrent to flow through the diode, which is the weak point of the rectifier.

The polarity reversal time of the DC high voltage generator can be controlled by appropriately selecting the peak current resistance, resistance and reactance of the diode composing the rectifier.

[0012]

[Embodiment 1] FIG. 4 shows a circuit diagram of an embodiment of a DC high voltage generator of the present invention. The AC power supply e represents a state at the moment when the polarities of the rectifiers RF1 and RF2 are reversed under the conditions that the peak value is 80 kV, the frequency is 50 Hz, the load resistance R is 100 kΩ, and the DC output voltage is 160 kV. At this time, the capacitor C2 forms a short circuit with the rectifiers RF2 and RF1. The circuit constant at this time is

[0013]

[Equation 1]

When α≈1.0, the peak value ip of the current flowing through this short circuit is

[0015]

[Equation 2]

The voltage drop time, that is, the conduction time t ₁ of the diode d is

[0017]

[Equation 3]

Reverse polarity voltage rise time t after polarity reversal
_In the case of no load, ₂ is charged every 1/2 cycle, so that the output voltage E0 = 2Eε ^{−1 is} charged in 2 cycles. Therefore, the voltage rise time t ₂ is

[0019]

[Equation 4]

This is shown in FIG. 5, and the polarity reversal time T according to the first embodiment of the present invention is 0.11 s as shown below.
Becomes

[0021]

[Equation 5]

The voltage rise time t ₂ can be shortened by increasing the power supply frequency. In the simulation at the power supply frequency of 10 kHz, the load reversal of 100 kΩ and the power supply impedance of 10 Ω showed the polarity reversal time T of 0.25 ms.

FIG. 5 shows the output voltage waveform of the DC high voltage generator according to the first embodiment when the polarity is inverted.

[0024]

[Embodiment 2] FIG. 6 is a circuit diagram showing an embodiment of a multi-stage series DC high voltage generator according to the present invention. This circuit is generally called a Cockcroft-Walton circuit, and in this embodiment, the DC output voltage is 500 k.
V, output current is 10 mA, and the voltage drop ΔV when 10 mA is energized is

[0025]

[Equation 6]

The output voltage E ₀ is

[0027]

[Equation 7]

Discharge current i flowing when the polarity of the rectifier is reversed
Is

[0029]

[Equation 8]

The conduction time t _{1 of the} diode is

[0031]

[Equation 9]

From the above results, the polarity reversal time T obtained by simulating the transient phenomenon at the time of polarity reversal was 0.01 seconds. The diode of the rectifier used in the DC high voltage generator has a reverse withstand voltage of 150 kV-DC, a forward current of 100 mA and a half cycle peak current of 45 A.

[0033]

According to the present invention, in a circuit during charging, even if the rectifying direction of the rectifier is switched in reverse, a polarity reversal time is 1 s or less without flowing a short circuit overcurrent in the rectifier circuit, which is an extremely short time. It is possible to provide a DC high voltage generator capable of safely and reliably reversing the polarity.

The above-mentioned effect is obtained by the extra high voltage in the electric power field,
It can provide extremely effective new technology for research and development such as insulation breakdown test of ultra high voltage power equipment, DC power transmission technology, frequency conversion technology, etc., and has industrially and practically great value.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a voltage doubler rectifier circuit including a rectifier in which a diode, a resistor and a reactance used in a DC high voltage generator according to the present invention are connected in series to invert the rectifying direction and invert the polarity.

2A and 2B are explanatory diagrams of polarity reversal of the DC high voltage generator, in which FIG. 2A is a diagram showing states before polarity reversal and FIG. 2B is a diagram showing states after polarity reversal.

FIG. 3 is a circuit diagram of a conventional example of polarity inversion switching of a DC high voltage generator.

FIG. 4 is a circuit configuration diagram of the DC high voltage generator according to the first embodiment of the present invention.

FIG. 5 is an output voltage waveform diagram at the time of polarity reversal of the DC high voltage generator according to the first embodiment of the present invention.

FIG. 6 is a circuit diagram of a DC high voltage generator according to a second embodiment in which rectifiers having a polarity reversing mechanism of the present invention are connected in multiple stages in series.

[Explanation of symbols]

e: AC power supply C1: Capacitor RF1: Rectifier RF2: Rectifier d: Diode configuring rectifier r: Resistor configuring rectifier l: Reactance configuring rectifier S: Changeover switch that reverses rectifier rectification direction C2: Capacitor T1: DC high voltage output terminal T2: DC high voltage output terminal D1: Diode D2: Diode +-: Charging polarity of capacitor i: Discharge current of capacitor C2 S1: Power switch S2: Discharge switch of capacitor C1 S3: Discharge switch of capacitor C2 R1: discharging resistor of the capacitor C1 R2: discharge resistance of the capacitor C2 R: load resistance E: DC output voltage t _1: energization time of the diode t _2: reverse polarity voltage rise time after polarity reversal T: polarity inversion time

Claims (2)

[Claims] 1. In a voltage doubler rectifier circuit comprising two diodes D1 and D2 connected to an AC power supply e and two capacitors C1 and C2, either or both of a resistor r and a reactance l are connected in series to a diode d. A DC high voltage generator characterized in that the rectifiers RF1 and RF2 connected to each other are inverted in rectification direction to invert polarity. 2. The DC high voltage generator according to claim 1, wherein a voltage doubler rectifier circuit comprising rectifiers RF1 and RF2 and capacitors C1 and C2 is connected in multiple stages in series.