JP6516062B2 - DC high voltage power supply - Google Patents

Description

  The present invention relates to a direct current high voltage power supply device, and more particularly to a direct current high voltage power supply device capable of switching positive and negative polarities of direct current high voltage output.

  In a mass spectrometer, various compounds in a sample are ionized, generated ions are separated and detected according to mass-to-charge ratio, and compounds are identified or quantified based on the detection signals. There are compounds which are easy to be positively ionized and compounds which are easy to be negatively ionized. Therefore, in a chromatograph mass spectrometer combining a chromatograph such as a gas chromatograph (GC) or liquid chromatograph (LC) and a mass spectrometer, in order to detect various compounds as closely as possible, measurement of positive ions and It is desirable to carry out the measurement together with the negative ion. Therefore, as disclosed in Patent Document 1 and Non-patent Document 1 etc., the conventional chromatograph mass spectrometer has a function of repeatedly performing measurement while alternately switching the positive ion measurement mode and the negative ion measurement mode. ing.

  In the positive ion measurement mode and the negative ion measurement mode, for example, it is necessary to switch the polarity of the voltage applied to each part such as an ion source of a mass spectrometer, a mass separator, and an ion detector. For example, in a reflectron time-of-flight mass spectrometer, a pulse voltage applied to an accelerating electrode when injecting ions into the flight space, a DC voltage applied to a reflecting electrode of a reflectron, a microchannel plate of ion detectors, and multistages It is necessary to switch the polarity of the DC voltage or the like applied to the dynode or the like according to the polarity of the ion to be detected. In order to switch the positive ion measurement mode and the negative ion measurement mode at high speed, it is necessary to switch the polarity of various applied voltages at high speed as described above, and it is a DC that can switch the polarity of output voltage of one system at high speed. High voltage power supplies are conventionally used.

  FIG. 4 is an equivalent circuit of an example of a conventional DC high voltage power supply device. This power supply device includes a positive voltage generating unit 1A generating positive high voltage + HV, a negative voltage generating unit 1B generating negative high voltage -HV, a high voltage switch 3A on the positive side, and a negative side. High voltage switch 3 B, protection resistors 5 A and 5 B for limiting surge current flowing to the high voltage switches 3 A and 3 B, and in parallel with load 100 for stabilizing the potential of load 100 connected to voltage output terminal 6 It includes output capacitor 4 connected, and discharge resistors 9A and 9B connected in parallel to the output end of positive voltage generation unit 1A and the output end of negative voltage generation unit 1B, respectively. The positive voltage generation unit 1A includes an excitation circuit 1A1 that outputs an AC high voltage, a rectifier circuit 1A2 that converts the AC high voltage to a DC high voltage, and a filter circuit 1A3 that removes a ripple component included in the DC high voltage. including. Similarly, the negative voltage generation unit 1B includes an excitation circuit 1B1 that outputs an AC high voltage, a rectifier circuit 1B2 that converts the AC high voltage to a DC high voltage, and a filter circuit 1B3 that removes a ripple component included in the DC high voltage. And. The discharging resistors 9A and 9B are for discharging the charges accumulated in the capacitors 21A and 21B included in the rectifier circuits 1A2 and 1B2, the capacitors 31A and 31B included in the filter circuits 1A3 and 1B3, and the output capacitor 4. is there.

  Generally, the excitation circuits 1A1 and 1B1 are AC-DC converters for converting commercial AC power into DC power to generate AC high voltage of several kV or more, and switching for switching DC current by the AC-DC converter. It includes an element, a transformer including a primary winding to which the switched current is supplied, and the like.

  FIG. 6 is an operation explanatory diagram of this DC high-voltage power supply device, and FIG. 5 is a waveform diagram of the voltage HVout output from the voltage output terminal 6. In FIG. 6, Phase [1] is a state in which a positive high voltage + HV is constantly output, and Phase [5] is a state in which a negative high voltage −HV is steadily output. When changing the polarity of this output voltage from positive to negative, the state of each part is from Phase [2] → [3] → [4] from Phase [1] steady voltage steady output state. The negative voltage steady output state of [5] changes in order. On the other hand, when changing the polarity of the output voltage from negative to positive, the state of each part is from Phase [6] → [7] → [8] from the steady state negative voltage output of Phase [5]. It changes in order until the positive voltage steady output state of Phase [1]. Each period of [1] to [8] in FIG. 5 corresponds to Phase [1] to Phase [8] in FIG.

Hereinafter, the operation at the time of polarity switching will be described.
As shown in FIG. 6A, in Phase [1], the positive electrode side excitation circuit 1A1 is in the on (operation) state, and the positive electrode side high voltage switch 3A is also in the on (closed) state. On the other hand, the negative electrode side excitation circuit 1B is in the off (non-operation) state, and the negative electrode side high voltage switch 3B is also in the off (opened) state. At this time, the DC positive voltage + HV generated by the positive voltage generation unit 1A is applied to the load 100 and the output capacitor 4 via the high voltage switch 3A and the protective resistor 5A. As indicated by thick arrows in FIG. 6A, the current flows (however, the description of the current flowing to the load 100 is omitted), and the output capacitor 4 and the capacitor 31A in the filter circuit 1A3 are each shown in FIG. a) It is stored as described in a). Although the capacitor 21A in the rectifier circuit 1A2 is also stored in a similar manner, the capacity of the capacitor 21A is usually neglected because it is sufficiently smaller than the capacity of the capacitor 31A in the filter circuit 1A3. The same applies to the following description.

  In the next phase [2], the operation of the positive electrode side excitation circuit 1A1 is stopped (turned off) while the positive electrode side high voltage switch 3A is maintained in the on (closed) state. The charges accumulated in the capacitor 31A and the output capacitor 4 in the positive side filter circuit 1A3 until just before that are discharged through the discharging resistor 9A as shown by the thick arrow and the thick dotted arrow in FIG. 6 (b). . As a result, the output voltage HVout drops exponentially from + HV as shown in FIG. The resistance value of the protective resistor 5A is sufficiently small compared to the resistance value of the discharging resistor 9A and can be ignored. Therefore, the time constant of discharge is determined by the resistance value of discharge resistor 9A and the capacitance value of capacitor 31A in filter circuit 1A3 (strictly speaking, the parallel combined capacitance value of capacitor 31A and capacitor 21A in positive side rectification circuit 1A2 And the parallel combined capacitance value of the capacitance value of the output capacitor 4.

  In Phase [3], after the output voltage HVout becomes almost zero, the positive electrode side high voltage switch 3A is switched from the on (closed) state to the off (opened) state, while the negative electrode side high voltage switch 3B is turned off (opened) Switch from state to on (closed).

  In the subsequent phase [4], the negative electrode side excitation circuit 1B1 is switched from the off (non-operation) state to the on (operation) state. As a result, a current flows as indicated by thick arrows in FIG. The output capacitor 4 is charged to the negative polarity, and the output voltage HVout rises to the negative polarity side as shown in FIG. Then, when the output voltage HVout reaches a predetermined negative voltage -HV, the phase shifts from Phase [4] to [5].

In Phase [5], the negative electrode side excitation circuit 1B1 is maintained in the on (operation) state, and the negative electrode side high voltage switch 3B is maintained in the on (closed) state. At this time, the direct current negative voltage -HV generated by the negative voltage generation unit 1B is applied to the load 100 and the output capacitor 4 via the high voltage switch 3B and the protection resistor 5B. Up to this point, the polarity switching from the positive polarity to the negative polarity is completed.

  In Phase [6], the operation of the negative electrode side excitation circuit 1B1 is stopped (turned off) while the negative electrode side high voltage switch 3B is maintained in the on (closed) state. The charges accumulated in the capacitor 31B and the output capacitor 4 in the negative electrode side filter circuit 1B3 until just before that are discharged through the discharging resistor 9B as shown by the thick arrow and the thick dotted arrow in FIG. . As a result, the output voltage HVout drops exponentially from -HV as shown in FIG. The resistance value of the protective resistor 5B is sufficiently small compared to the resistance value of the discharging resistor 9B and can be ignored. Therefore, the time constant of discharge is determined by the resistance value of discharge resistor 9B and the capacitance value of capacitor 31B in filter circuit 1B3 (strictly speaking, the parallel combined capacitance value of capacitor 31B and capacitor 21B in positive side rectification circuit 1B2 And the parallel combined capacitance value of the capacitance value of the output capacitor 4.

  In Phase [7], after the output voltage HVout becomes almost zero, the negative high voltage switch 3B is switched from the on (closed) state to the off (open) state, while the positive high voltage switch 3A is turned off (open) Switch from state to on (closed).

  In Phase [8], the positive pole side excitation circuit 1A1 is switched from the off (non-operation) state to the on (operation) state. As a result, current flows as indicated by thick arrows in FIG. 6 (h). The output capacitor 4 is charged to the positive polarity, and the output voltage HVout rises to the positive polarity side as shown in FIG. Then, when the output voltage HVout reaches a predetermined positive voltage + HV, the phase [8] is shifted to [1].

  As shown in FIG. 5, the time required to switch the polarity of the output voltage HVout from positive to negative or vice versa, that is, the polarity inversion time tR is the capacitors 21A, 21B in the rectifier circuits 1A2, 1B2, the filter circuit 1A3, A discharge time td for reducing the output voltage HVout to almost zero by discharging the charges accumulated in the capacitors 31A and 31B and the output capacitor 4 in 1B3 through the discharge resistors 9A and 9B, the high voltage switch 3A, This time is the sum of the switching time ts required for switching 3B and the charging time tc for raising the output voltage HVout to the desired voltage value ± HV by operating the excitation circuits 1A1 and 1B1 from the non-operating state.

  The discharge time td is the resistance value of the discharge resistors 9A and 9B, the positive and negative voltage generating portions 1A and 1B side capacitors (capacitors 21A and 21B in the rectification circuits 1A2 and 1B2 and capacitors 31A and 31B in the filter circuits 1A3 and 1B3) And the parallel combined capacitance value of the output capacitor 4 and the capacitance value of the output capacitor 4 are proportional to the time constant. The charging time tc is inversely proportional to the current capacity that can be supplied by the positive and negative voltage generating units 1A and 1B. Therefore, assuming that the switching time ts of the high voltage switches 3A and 3B is constant, in order to shorten the polarity inversion time tR, the above time constant is reduced to shorten the discharge time td, or the voltage generator 1A, It is necessary to increase the current capacity of 1 B to reduce the charging time tc, or both. However, increasing the current capacity of the voltage generation units 1A and 1B has limitations because it leads to an increase in the cost of the device and an increase in the size and weight of the device. In addition, when the capacitances of the capacitors included in the voltage generation units 1A and 1B and the capacitance of the output capacitor 4 are reduced, ripples and noise of the output voltage may increase, which is also limited. Therefore, generally, the method of shortening the discharge time td can not be adopted by reducing the resistance value of the discharge resistors 9A and 9B.

  However, when the resistance value of the discharge resistors 9A and 9B is reduced, the current flowing to the resistors 9A and 9B at the time of steady output increases, power consumption increases, and the heat generation amount increases. Therefore, there is a problem that the temperature rise inside the power supply device becomes large, and the stability of the output voltage is deteriorated. In order to avoid this, it is necessary to promote heat radiation near the discharge resistors 9A and 9B, which leads to enlargement of the apparatus and the like. Further, the increase in power consumption by the discharge resistors 9A and 9B requires the current capacity of the voltage generation units 1A and 1B to be increased accordingly, which leads to an increase in the cost of the apparatus, although the difference is more or less.

JP, 2001-99821, A

"LCMS-IT-TOF liquid chromatograph mass spectrometer positive / negative ion high-speed switching measurement", [online], Shimadzu Corporation, [search on February 3, 2016], Internet <URL: http://www.an .shimadzu.co.jp / lcms / it-tof3.htm>

  The present invention has been made to solve the above problems, and the object of the present invention is to suppress the increase in the cost of the device, the increase in size and weight, and the temperature rise in the device as much as possible. It is an object of the present invention to provide a DC high voltage power supply capable of speeding up the switching of the polarity of

The present invention, which has been made to solve the above problems, relates to a DC high voltage power supply device that selectively outputs DC high voltage of positive and negative polarities.
a) A positive voltage generating unit that includes a positive side AC voltage generating unit that generates an alternating voltage, and a rectifying and smoothing unit that rectifies and smoothes the AC voltage, and outputs a positive DC high voltage;
b) A negative voltage generating unit for generating an alternating voltage, and a rectifying / smoothing unit for rectifying and smoothing the alternating voltage, and outputting a negative high-voltage DC voltage,
c) When the DC high voltage is output to the voltage output end of the positive voltage generation unit and the voltage output end of the negative voltage generation unit, the voltage output end is reversely biased by the voltage. With each connected diode,
d) a first output circuit connected in series between a positive electrode side switch and a protection resistor, which is connected between the voltage output terminal of the positive voltage generation unit and the positive / negative switching voltage output terminal which is common to positive and negative;
e) a second output circuit connected between an output terminal of the negative voltage generation unit and the positive / negative switching voltage output terminal and in which a negative side switch and a protection resistor are connected in series;
f) an output capacitor connected in parallel with a load connected to the positive / negative switching voltage output terminal;
g) When switching the positive and negative polarities of the output voltage from the positive and negative switching voltage output terminal, the positive electrode side switch is performed with both the positive electrode side AC voltage generation unit and the negative electrode side AC voltage generation unit stopped. And a control unit that controls the operations of the positive electrode side AC voltage generation unit and the negative electrode side AC voltage generation unit, and the opening / closing operation of the positive electrode side switch and the negative electrode side switch so as to close both the negative electrode side switches. When,
It is characterized by having.

  In the DC high-voltage power supply according to the present invention, when a positive voltage is constantly output to a load connected to the positive / negative switching voltage output terminal, the positive switch is closed and the negative switch is opened. The positive side AC voltage generating unit is in the operating state, and the negative side AC voltage generating unit is in the non-operating state, that is, in the stop state. When a high voltage of negative polarity to the load is constantly output, the positive switch is open and the negative switch is closed, the negative AC voltage generator is in operation, and the positive AC voltage generator. Is in the non-operational state, that is, in the stop state. In any case, the power supplied from the positive voltage generating unit or the negative voltage generating unit to the load stores the capacitor included in the output capacitor or the rectifying and smoothing unit.

  For example, when switching the polarity of a positive voltage from negative to positive output voltage from the output terminal to negative, the controller stops the operation of the positive AC voltage generator and closes the negative switch. Create As a result, the operation of the AC voltage generation unit is stopped on both the positive electrode side and the negative electrode side, while the switch is closed on both the positive electrode side and the negative electrode side. As a result, the charge stored positively in the output capacitor is released through the second output circuit and the diode on the negative electrode side. On the other hand, the charge stored in the capacitor included in the rectifying / smoothing unit of the positive voltage generation unit is released through the first output circuit, the second output circuit, and the diode on the negative electrode side.

  That is, a loop is formed that includes the second output circuit that was not conventionally formed because the negative switch was not closed, and discharge is achieved through the loop. Although the protective resistance is included in the loop, if the resistance value of the protective resistance is reduced, the time constant is small, so discharge is performed rapidly and the output voltage becomes zero in a short time. In addition, since the loop includes a diode connected in the forward direction in the direction of discharge current, the discharge current is prevented from flowing to the rectifying / smoothing unit of the negative voltage generation unit connected in parallel with the diode. Can. Then, after the output voltage becomes almost zero, the control unit opens the switch on the positive electrode side and starts the operation of the negative electrode side AC voltage generation unit, thereby generating the negative high voltage generated by the negative voltage generation unit. Can be output from the positive / negative switching voltage output terminal.

When the polarity of the voltage is switched to positive from the state where the negative high voltage is outputted from the positive / negative switching voltage output terminal, the reverse operation to the above may be performed.
Thus, in the DC high-voltage power supply device according to the present invention, when the polarity of the output voltage is switched, the charge stored in the capacitor included in the positive voltage generation unit or the negative voltage generation unit that is the power supply is It is possible to quickly release both of the charges stored in the receiving output capacitor. As a result, the output voltage becomes almost zero in a short time, so that the time required to switch the polarity of the output voltage can be made shorter than in the past.

  According to the DC high-voltage power supply device according to the present invention, the time required to switch the polarity of the output voltage can be shortened as compared with the conventional device. Thus, if the DC high-voltage power supply according to the present invention is used as a power supply for various electrodes in, for example, a mass spectrometer of a chromatograph mass spectrometer, switching between a positive ion measurement mode and a negative ion measurement mode can be performed quickly. It is possible to shorten the unmeasurable period associated with the switching of the measurement mode and reduce the omission of component detection. In addition, the cycle of switching between the positive ion measurement mode and the negative ion measurement mode can be shortened to create a better chromatogram.

The equivalent circuit schematic of the direct current | flow high voltage | pressure power supply device by one Example of this invention. The wave form diagram of the output voltage at the time of the positive / negative polarity switching of the direct current | flow high voltage power supply device of a present Example. Operation | movement explanatory drawing of the direct current | flow high voltage power supply device of a present Example. The equivalent circuit schematic of an example of the conventional direct current | flow high voltage power supply device. FIG. 5 is a waveform diagram of an output voltage at the time of positive / negative polarity switching of the DC high-voltage power supply device shown in FIG. 4. Operation | movement explanatory drawing of the direct current | flow high voltage power supply device shown in FIG.

  Hereinafter, an embodiment of a DC high-voltage power supply according to the present invention will be described in detail with reference to FIGS. 1 to 3. FIG. 1 is an equivalent circuit diagram of the DC high voltage power supply device according to the present embodiment, FIG. 2 is a waveform diagram of output voltage at the time of positive / negative polarity switching of the DC high voltage power supply device of the present embodiment, and FIG. FIG. The same components as those of the conventional DC high-voltage power supply described with reference to FIG. 4 are denoted by the same reference numerals.

  As apparent from the comparison between FIG. 1 and FIG. 4, in the DC high voltage power supply device of this embodiment, a positive voltage generation unit 1A, a negative voltage generation unit 1B, high voltage switches 3A and 3B such as MOSFETs, protection resistors The configurations of 5A, 5B, output capacitor 4 and the like are the same as those of the conventional DC high voltage power supply. One of the differences between the DC high-voltage power supply device of this embodiment and the conventional device is that instead of the discharge resistors 9A and 9B connected to the output terminals of the positive voltage generation unit 1A and the negative voltage generation unit 1B, The diodes 2A and 2B are provided. The discharge diodes 2A and 2B are both connected in the reverse bias state by the voltages when the voltages are output to the output terminals of the positive voltage generation unit 1A and the negative voltage generation unit 1B. The high voltage switches 3A and 3B are on / off driven by the drive unit 8, and the drive unit 8 and the excitation circuits 1A1 and 1B1 operate according to control signals supplied from the control unit 7. The control sequence at the time of positive / negative polarity switching of the output voltage is different from that of the conventional device.

Hereinafter, this control sequence and the operation of each part associated therewith will be described with reference to FIG. 2 and FIG.
Similar to FIG. 6, in FIG. 3, Phase [1] is a state in which high voltage + HV of positive polarity is constantly output, and Phase [5] is a state in which high voltage −HV of negative polarity is constantly output. . When changing the polarity of the output voltage from positive to negative, the state of each part is from Phase [2] → [3] → [4] and Phase [2] from the steady voltage output state of Phase [1]. The negative voltage steady output state of 5] is sequentially changed. On the other hand, when changing the polarity of the output voltage from negative to positive, the state of each part is from Phase [6] → [7] → [8] from the steady state negative voltage output of Phase [5]. It changes in order until the positive voltage steady output state of Phase [1]. Each period of [1] to [8] in FIG. 2 corresponds to Phase [1] to Phase [8] in FIG.

As shown in FIG. 3A, in Phase [1], the positive electrode side excitation circuit 1A1 is in the on (operation) state, and the positive electrode side high voltage switch 3A is in the on (closed) state. On the other hand, the negative electrode side excitation circuit 1B is in the off (non-operation) state, and the negative electrode side high voltage switch 3B is in the off (opened) state. At this time, the DC positive voltage + HV generated by the positive voltage generation unit 1A is applied to the load 100 and the output capacitor 4 via the high voltage switch 3A and the protective resistor 5A. As indicated by thick arrows in FIG. 3A, a current flows (however, the description of the current flowing through the load 100 is omitted), and the output capacitor 4 and the capacitor 31A in the filter circuit 1A3 are each shown in FIG. a) Accumulate with the polarity as described in a). The flow of current at this time is exactly the same as Phase [1] in the conventional device shown in FIG. 6 (a).

  In the next phase [2], under the control of the control unit 7, the operation of the positive pole side excitation circuit 1A1 is stopped (off) while the positive pole side high voltage switch 3A is maintained in the on (closed) state. ). Also, the negative electrode side high voltage switch 3B is switched from the off (opened) state to the on (closed) state. That is, in this Phase [2], both of the excitation circuits 1A1 and 1B1 are in the non-operating state, while both of the high voltage switches 3A and 3B are in the on state. As a result, the charge accumulated in the capacitor 31A in the positive side filter circuit 1A3 until just before that is indicated by the thick arrow in FIG. 3B, the positive side high voltage switch 3A, the positive side protection resistor 5A, The battery is discharged in a closed loop including the negative electrode side protective resistor 5B, the negative electrode side high voltage switch 3B and the negative electrode side discharge diode 2B, and is consumed by the protective resistors 5A and 5B (converted to heat). On the other hand, the charge stored in the output capacitor 4 is a closed loop including the negative side protection resistor 5B, the negative side high voltage switch 3B, and the negative side discharge diode 2B as shown by the thick dotted arrow in FIG. 3 (b). And is consumed by the protective resistor 5B.

  As is clear from a comparison between FIG. 3 (b) and FIG. 6 (b), in the DC high-voltage power supply device of this embodiment, both high voltage switches 3A and 3B are turned on. A loop including 5B, the negative electrode side high voltage switch 3B, and the negative electrode side discharge diode 2B is formed, and discharge through this loop becomes possible. At this time, for example, if there is no negative electrode side discharge diode 2B, a large discharge current passing through the negative electrode side protective resistor 5B and the negative electrode side high voltage switch 3B flows to the negative voltage generation portion 1B, and the voltage generation portion 1B Since there is a risk of breaking the circuit element, it is necessary to take measures such as using an element that can withstand it. On the other hand, in this power supply device, it is possible to prevent the discharge current from flowing to the negative voltage generating portion 1B by the negative electrode side discharge diode 2B, and the above countermeasure is unnecessary in the voltage generating portions 1A and 1B.

Since the charges accumulated in the capacitors 21A and 31A and the output capacitor 4 are discharged through the above-described paths, assuming that the capacitance values of the capacitors 21A and 31A are sufficiently smaller than the capacitance value of the output capacitor 4, the discharge The time constant depends on the product of the resistance value of the negative electrode side protection resistor 5 B and the capacitance value of the output capacitor 4. The resistance values of the protective resistors 5A and 5B are considerably smaller than the resistance values of the discharge resistors 9A and 9B in the conventional device. Therefore, the time constant of this discharge is smaller than that of the conventional device, and as shown in FIG. 2, the output voltage HVout becomes zero in a short time.

  In Phase [3], after the output voltage HVout becomes almost zero, the positive-electrode high-voltage switch 3A is turned off (opened) from the on-state (closed) while the negative-electrode high-voltage switch 3B is maintained in the off state. Switch. As a result, the same state as Phase [3] in the conventional device shown in FIG. 6 (c) is obtained.

  Then, in Phase [4], the negative electrode side excitation circuit 1B1 is switched from the off (non-operation) state to the on (operation) state. As a result, a current flows as indicated by a thick arrow in FIG. The output capacitor 4 is charged to the negative polarity, and the output voltage HVout rises to the negative polarity side as shown in FIG. Then, when the output voltage HVout reaches a predetermined negative voltage -HV, the phase shifts from Phase [4] to [5].

In Phase [5], the negative electrode side excitation circuit 1B1 is maintained in the on (operation) state, and the negative electrode side high voltage switch 3B is maintained in the on (closed) state. At this time, the direct current negative voltage -HV generated by the negative voltage generation unit 1B is applied to the load and the output capacitor 4 through the high voltage switch 3B and the protection resistor 5B. Up to this point, the polarity switching from the positive polarity to the negative polarity is completed.

  In Phase [6], the operation of the negative electrode side excitation circuit 1B1 is stopped (turned off) while the negative electrode side high voltage switch 3B is maintained in the on (closed) state under the control of the control unit 7. . Further, the positive electrode side high voltage switch 3A is switched from the off (opened) state to the on (closed) state. That is, in Phase [6], as in Phase [2], both of the excitation circuits 1A1 and 1B1 are in the non-operating state, while both of the high voltage switches 3A and 3B are in the on state. Thereby, the charge stored in the capacitor 31B in the negative electrode side filter circuit 1B3 until just before that is indicated by the thick arrow in FIG. 3 (f), the negative electrode side discharge diode 2A and the positive electrode side high voltage switch 3A. The battery is discharged in a closed loop including the positive electrode side protective resistor 5A, the negative electrode side protective resistor 5B and the negative electrode side high voltage switch 3B, and is consumed by the protective resistors 5A and 5B (converted to heat). On the other hand, the charge stored in the output capacitor 4 includes a positive discharge diode 2A, a positive protection resistor 5A, and a high voltage switch 3A as shown by the thick dotted arrow in FIG. 3 (f). It is discharged in a closed loop and consumed by the protection resistor 5A.

At this time, as in Phase [2], it is possible to prevent the discharge current from flowing to the positive voltage generation unit 1A by the discharge diode 2A for the positive electrode side. Since the charges accumulated in the capacitors 21A and 31A and the output capacitor 4 are discharged through the above-described paths, assuming that the capacitances of the capacitors 21A and 31A are sufficiently smaller than the capacitance of the output capacitor 4, The time constant of discharge depends on the product of the resistance value of the positive electrode side protective resistor 5 A and the capacitance value of the output capacitor 4. As described above, since the resistance values of the protective resistors 5A and 5B are considerably smaller than those of the discharge resistors 9A and 9B in the conventional device, the time constant of discharge is smaller than that of the conventional device, as shown in FIG. The output voltage HVout becomes zero in a short time.

  In Phase [7], after the output voltage HVout becomes substantially zero, the negative electrode side high voltage switch 3B is switched from the on (closed) state to the off (open) state. As a result, the same state as Phase [7] in the conventional device shown in FIG. 6 (g) is obtained.

  Then, in Phase [8], the positive pole side excitation circuit 1A1 is switched from the off (non-operation) state to the on (operation) state. As a result, as shown in FIG. 6 (h), current flows as indicated by thick arrows in FIG. 3 (h). The output capacitor 4 is charged to the positive polarity, and the output voltage HVout rises to the positive polarity side as shown in FIG. Then, when the output voltage HVout reaches a predetermined positive voltage + HV, the phase [8] is shifted to [1].

  Similar to the conventional device, the polarity inversion time tR is the sum of the discharge time td, the switching time ts, and the charging time tc. Among these, the switching time ts and the charging time tc are the same as in the conventional device. On the other hand, as described above, since the time constant of discharge is small, the discharge time td is shorter than that of the conventional device. As a result, the polarity inversion time tR is shortened as compared with the conventional device, and high-speed positive / negative switching is possible.

Here, the polarity inversion time tR of the DC high-voltage power supply device of this embodiment and the conventional device will be specifically compared. The conditions were set as follows for comparison.
(Condition 1) The output voltage ± HV of the positive and negative voltage generators 1A and 1B is ± 10 kV.
(Condition 2) The power supply capacity of the positive and negative voltage generators 1A and 1B is 10 W, and the output current is 1 mA.
(Condition 3) The capacitance of the output capacitor 4 including the capacitance of the load 100 is 10 nF, and the capacitances of the capacitors 21A, 31A, 21B, and 31B included in the voltage generation units 1A and 1B are all compared with the capacitance of the output capacitor 4 Small enough to be ignored. Further, the resistance value of the load 100 is sufficiently larger than the output impedance of the power supply device, and the current flowing through the load 100 can be ignored.
(Condition 4) The maximum switching power of the high voltage switches 3A and 3B is 100 W, and the switching time ts is 1 msec.
(Condition 5) The steady power consumption in the discharge resistors 9A and 9B in the conventional device is 1 W or less.

  From (condition 1), (condition 2) and (condition 3), the charging time tc is 10 [nF] × 10 [kV] / 1 [mA] = 100 for both the DC high voltage power supply device of this embodiment and the conventional device. It is calculated as [msec]. Further, from (Condition 4), the switching time ts is 1 [msec]. On the other hand, in the conventional device, from (condition 1) and (condition 5), the resistance value of the discharge resistors 9A and 9B is 10 [kV] ^ 2/1 [W] = 100 [MΩ]. The discharge time constant is 100 [MΩ] × 10 [nF] = 1 [sec], and the time for which the output voltage decreases to 3 times the time constant, that is, 5% of 10 kV which is the specified output voltage value. Assuming that the discharge time td, the discharge time td is 3 seconds. On the other hand, in the DC high voltage power supply device of the present embodiment, the resistance value of the protective resistors 5A and 5B is 10 [kV] ^ 2/100 [W] = 1 [MΩ] according to (Condition 4). The time constant of discharge is 1 [MΩ] × 10 [nF] = 10 [msec], and the discharge time td is 30 msec when the discharge time td is three times the time constant as described above.

  From the above, the polarity inversion time tR in the conventional device under the above conditions can be obtained as tR = td + Tc + ts = 3 sec + 1 msec + 100 msec = 3.101 sec. On the other hand, the polarity reversal time tR in the DC high-voltage power supply device of this embodiment is determined as tR = td + Tc + ts = 30 msec + 1 msec + 100 msec = 0.131 sec. From this, it is understood that in the DC high-voltage power supply device of this embodiment, the polarity inversion time tR can be shortened to 1/25 or less of that of the conventional device. Further, in the DC high-voltage power supply device of the present embodiment, no discharge resistance is required, and therefore no power loss (1 W under the above conditions) occurs during steady state output, and the temperature rise inside the power supply device by that amount. There is also an advantage that it can be suppressed. As a result, the instability of the output voltage due to the temperature rise is eliminated, which leads to the improvement of the stability of the output voltage.

  The above-described embodiment is merely an example of the present invention, and it is natural that any modification, addition, or modification can be made within the scope of the spirit of the present invention without departing from the scope of the present invention.

Further, since the circuit configuration shown in FIG. 1 is an equivalent circuit, it can be easily conceived by those skilled in the art that various implementations are possible in an actual circuit. For example, the high voltage switches 3A and 3B may be configured using other switching elements such as a bipolar transistor, an insulated gate bipolar transistor (IGBT), a mechanical relay, and the like in addition to the MOSFET. Further, since a high voltage of, for example, several kilovolts or more is applied to both ends of the discharge diodes 2A and 2B, the withstand voltage per one element can be suppressed by adopting a configuration in which a plurality of diodes and elements corresponding thereto are connected in series. Naturally also possible.
Also, the excitation circuits 1A1 and 1B1 may have any configuration as long as they can output an AC high voltage, but typically, as described above, an AC-DC converter that converts commercial AC power to DC power, The switching device may be configured to include a switching element such as a MOSFET for switching a direct current by the AC-DC converter, a transformer including a primary winding to which the switched current is supplied, and the like.

DESCRIPTION OF SYMBOLS 1A ... Positive voltage generation part 1B ... Negative voltage generation part 1A1, 1B1 ... Excitation circuit 1A2, 1B2 ... Rectification circuit 1A3, 1B3 ... Filter circuit 21A, 21B, 31A, 31B ... Capacitor 2A, 2B ... Discharge diode 3A, 3B ... High voltage switch 4 ... output capacitor 5A, 5B ... protection resistance 6 ... voltage output end 7 ... control unit 8 ... drive unit

Claims (1)

In a DC high-voltage power supply which selectively outputs DC high voltage of both positive and negative polarity,
a) A positive voltage generating unit that includes a positive side AC voltage generating unit that generates an alternating voltage, and a rectifying and smoothing unit that rectifies and smoothes the AC voltage, and outputs a positive DC high voltage;
b) A negative voltage generating unit for generating an alternating voltage, and a rectifying / smoothing unit for rectifying and smoothing the alternating voltage, and outputting a negative high-voltage DC voltage,
c) When the DC high voltage is output to the voltage output end of the positive voltage generation unit and the voltage output end of the negative voltage generation unit, the voltage output end is reversely biased by the voltage. With each connected diode,
d) a first output circuit connected in series between a positive electrode side switch and a protection resistor, which is connected between the voltage output terminal of the positive voltage generation unit and the positive / negative switching voltage output terminal which is common to positive and negative;
e) a second output circuit connected between an output terminal of the negative voltage generation unit and the positive / negative switching voltage output terminal and in which a negative side switch and a protection resistor are connected in series;
f) an output capacitor connected in parallel with a load connected to the positive / negative switching voltage output terminal;
g) When switching the positive and negative polarities of the output voltage from the positive and negative switching voltage output terminal, the positive electrode side switch is performed with both the positive electrode side AC voltage generation unit and the negative electrode side AC voltage generation unit stopped. And a control unit that controls the operations of the positive electrode side AC voltage generation unit and the negative electrode side AC voltage generation unit, and the opening / closing operation of the positive electrode side switch and the negative electrode side switch so as to close both the negative electrode side switches. When,
A DC high voltage power supply device comprising:

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