Power supply devices, laser devices

Abstract

To provide a power supply device that can effectively reduce overvoltage even only with hardware.SOLUTION: A power supply device 250 driving a laser resonator 200 including a pair of discharge electrodes comprises a high frequency power supply that applies high frequency voltage VRF to a resonance circuit including the capacity of the pair of discharge electrodes, and a clamp circuit 600 that is provided between the high frequency power supply and the resonance circuit, and restricts the high frequency voltage VRF within a predetermined range. The high frequency power supply includes a charging capacitor 411 that is charged by a charging circuit, an inverter 412 that converts the DC voltage of the charging capacitor 411 into an AC voltage, and a step-up transformer 413 that steps up the AC voltage to generate the high frequency voltage VRF. The clamp circuit 600 includes a transformer 620 that is provided in parallel to the step-up transformer 413, and a rectification circuit 630 that is connected with a side of the high frequency power supply 400 of the transformer 620 and can charge the charging capacitor 411.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a laser device and the like. [Background technology]

[0002] Laser processing machines are widely used as industrial processing tools. Laser processing machines use high-power gas lasers such as CO2 lasers. FIG. 1 is a functional block diagram of a laser processing machine or laser apparatus 100R. The laser apparatus 100R includes a laser resonator 200 and a power supply unit 250R. The laser resonator 200 includes a pair of discharge electrodes 202 and 204, a total reflecting mirror 206, and a partial reflecting mirror 208.

[0003] A pair of discharge electrodes 202, 204 are provided in a gas chamber filled with a laser medium gas such as CO2. A capacitance C exists between the pair of discharge electrodes 202, 204. This capacitance C and an inductor L (an inductor element or a parasitic inductor) form a resonant frequency F RES A resonant circuit 210 having the following is formed.

[0004] The power supply 250R that drives the laser resonator 200 supplies a high-frequency voltage V RF is applied to the resonant circuit 210. RF The frequency F RF (hereinafter also referred to as the synchronization frequency) is the resonant frequency F RES The high frequency voltage V RF When a voltage is applied, a discharge current flows between the pair of discharge electrodes 202, 204. This discharge current excites the laser medium gas, forming a population inversion for laser oscillation or stimulated emission. The stimulated emission light from the population inversion travels back and forth within the optical resonator formed by the total reflecting mirror 206 and the partial reflecting mirror 208, and is amplified as it passes through the excited laser medium gas. A portion of the amplified stimulated emission light is extracted as output (laser light) from the partial reflecting mirror 208.

[0005] The power supply 250R generates a regulated DC voltage V DCa DC power supply 300 that generates a DC voltage V DC is the high frequency voltage V RF and applies the converted signal to the resonant circuit 210. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-192715 Summary of the Invention [Problem to be solved by the invention]

[0007] In an open state due to a poor connection between the discharge electrodes 202 and 204 or in a light load state such as when the laser is not emitting light, the capacitance C between the discharge electrodes 202 and 204 becomes extremely small, and the resonant frequency of the resonant circuit 210 (hereinafter referred to as the abnormal resonant frequency F RES As a result, the synchronous frequency F RF and the abnormal resonance frequency F of the resonant circuit 210 RES A large deviation occurs (F RF <F RES '), an excessive high-frequency voltage V RF In this specification, when simply referring to the "resonance frequency", unless otherwise specified, it refers to the normal resonant frequency F RES In addition, the normal resonant frequency F RES The abnormal resonance frequency F RES When specifically distinguishing from the normal resonant frequency (F RES ) is sometimes expressed as

[0008] Patent Document 1 discloses an overvoltage suppression element, such as a gas arrester or varistor, that temporarily suppresses the overvoltage across a resonant circuit to suppress excessive high-frequency voltages applied to the resonant circuit. The overvoltage suppression element can withstand the overvoltage for a limited time, and if a protection circuit detects an abnormality during that time, it stops the application of high-frequency voltage to the resonant circuit through software control. However, in addition to the short lifespan of the overvoltage suppression element, which is directly subjected to the overvoltage when an abnormality occurs, there is also the problem of slow operation of the protection circuit, which is software-controlled.

[0009] The present invention has been made in view of the above circumstances, and has as its object to provide a power supply device or the like that can effectively suppress overvoltage using hardware alone. [Means for solving the problem]

[0010] In order to solve the above problems, a power supply device according to one embodiment of the present invention is a power supply device for driving a laser resonator including a pair of discharge electrodes, and includes: a high-frequency power supply that applies a high-frequency voltage to a resonant circuit including the capacitance of the pair of discharge electrodes; and a vibration suppression circuit that is provided between the high-frequency power supply and the resonant circuit and that suppresses vibrations outside the resonant frequency band of the resonant circuit at the high-frequency voltage.

[0011] According to this aspect, the vibration suppression circuit provided between the high frequency power supply and the resonant circuit can suppress vibration outside the normal resonant frequency band. The excessive high frequency voltage generated in an open state or a light load state is suppressed within the normal resonant frequency (F RES ) higher than the abnormal resonance frequency (F RES This is caused by high-frequency vibrations of the resonant frequency band (abnormal resonant frequency band). In the present invention, by configuring a vibration suppression circuit using only hardware that can non-temporarily or steadily suppress high-frequency vibrations at abnormal resonant frequencies outside the normal resonant frequency band, it is possible to suppress overvoltage faster than the software-controlled method disclosed in Patent Document 1. Examples of vibration suppression circuits include a damping circuit that selectively attenuates currents at frequencies outside the normal resonant frequency band, and a clamp circuit that limits high-frequency voltages at frequencies outside the normal resonant frequency band to within a predetermined range.

[0012] Another aspect of the present invention is a laser device comprising: a laser resonator including a pair of discharge electrodes; a high-frequency power supply that applies a high-frequency voltage to a resonant circuit including a capacitance of the pair of discharge electrodes; and a vibration suppression circuit that is provided between the high-frequency power supply and the resonant circuit and that suppresses vibration of the resonant circuit at the high-frequency voltage outside the resonant frequency band.

[0013] Any combination of the above components and any conversion of these expressions into methods, devices, systems, recording media, computer programs, etc. are also encompassed by the present invention. [Effects of the Invention]

[0014] According to the present invention, overvoltage can be effectively suppressed using hardware alone. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a functional block diagram of the laser device. [Figure 2] 1 is a functional block diagram of a laser device according to a first embodiment. [Figure 3] 3 shows an example of the main circuit configuration of the power supply device of FIG. 2. [Figure 4] 10 shows a reference example of a high frequency voltage when a laser resonator is switched to an open-load state in a power supply device that is not provided with a vibration suppression circuit. [Figure 5] 10 shows an example of a high-frequency voltage when the laser resonator is switched to an open-load state in the power supply device according to the first embodiment. [Figure 6] FIG. 10 is a functional block diagram of a laser device according to a second embodiment. [Figure 7] An example of the main circuit configuration of the power supply device of FIG. 6 is shown. [Figure 8] 10 shows an example of a high-frequency voltage when the laser resonator is switched to an open-load state in the power supply device according to the second embodiment. [Figure 9] FIG. 10 is a functional block diagram of a laser device according to a third embodiment. [Figure 10] 10 shows an example of the main circuit configuration of the power supply device of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, a mode for carrying out the present invention (hereinafter also referred to as an embodiment) will be described in detail with reference to the drawings. In the description and / or drawings, identical or equivalent components, members, processes, etc. will be assigned the same reference numerals, and redundant explanations will be omitted. The scale and shape of each part shown in the drawings are set for convenience to simplify the explanation, and should not be interpreted as limiting unless otherwise specified. The embodiment is an example and does not limit the scope of the present invention in any way. All features and combinations thereof described in the embodiment are not necessarily essential to the present invention.

[0017] FIG. 2 is a functional block diagram of a laser device 100 according to a first embodiment of the present invention. The laser device 100 includes a commercial power supply 10, a DC power supply 300, a high-frequency power supply 400, a damping circuit 500, a resonant inductor L, and a laser resonator 200. A power supply device 250 according to the first embodiment of the present invention is configured by all or part of the DC power supply 300, the high-frequency power supply 400, and the damping circuit 500. Functional blocks of the power supply device 250 that require software control are realized by the cooperation of hardware resources, such as a central processing unit (CPU), memory, input devices, output devices, and peripheral devices connected to the computer, and software executed using these resources. Regardless of the type or location of the computer, each of the functional blocks described above may be realized by the hardware resources of a single computer or by combining hardware resources distributed across multiple computers.

[0018] The DC power supply 300 includes an AC-DC converter 310, a DC-DC converter 320, a DC link voltage detector 330, a high frequency voltage command calculator 340, a duty determiner 350, and a PWM signal generator 360. The AC-DC converter 310 converts an AC voltage, such as a three-phase AC voltage, supplied from the commercial power supply 10 into a DC voltage. The DC-DC converter 320 converts the DC voltage converted by the AC-DC converter 310 into a DC voltage suitable for laser oscillation operation of the laser device 100. The DC-DC converter 320 includes switching elements, such as transistors, whose switching is controlled by a PWM (Pulse Width Modulation) signal generated by the PWM signal generator 360. Hereinafter, the DC voltage converted by the DC-DC converter 320 will be referred to as a DC voltage V DC and DC link voltage V DC The DC link voltage detection unit 330 detects the DC link voltage V generated by the DC-DC conversion unit 320. DC is detected and fed back to the duty determining section 350.

[0019] The high-frequency voltage command calculation unit 340 calculates the high-frequency voltage V that the high-frequency power supply 400 should generate based on feedback of information indicating the operation and / or state of the laser resonator 200. RF and / or the DC link voltage V that the DC power supply 300 should generate. DC The information fed back from the laser resonator 200 to the high-frequency voltage command calculation unit 340 includes, for example, the intensity of the laser light oscillated by the laser resonator 200, and the current flowing through the pair of discharge electrodes 202, 204 and / or the resonance inductor L. The duty determination unit 350 calculates a command for the DC link voltage V detected by the DC link voltage detection unit 330. DC The PWM signal generating unit 360 determines the duty ratio of the PWM signal (pulse wave) to be generated based on the high-frequency voltage command calculated by the high-frequency voltage command calculating unit 340. The PWM signal generating unit 360 generates a PWM signal having the duty ratio determined by the duty determining unit 350 and applies it to the switching element of the DC-DC converting unit 320.

[0020] The high frequency power supply 400 includes a DC-RF converter 410 and a high frequency signal generator 420. The DC-RF converter 410 converts the DC link voltage V generated by the DC power supply 300 into a high frequency signal. DC , the synchronous frequency F RF High frequency voltage V RF As shown in FIG. 3, which will be described later, the DC-RF conversion unit 410 converts the DC link voltage V DC AC voltage V AC an inverter 412 that converts the AC voltage V AC is boosted to produce the high frequency voltage V RF The inverter 412 includes a step-up transformer 413 that generates a high-frequency signal for controlling the switching of the transistors of the inverter 412. The high-frequency signal has a switching frequency F SW is the high frequency voltage V RF The synchronous frequency F RF Also, the synchronization frequency F RF is the normal resonant frequency F of the resonant circuit 210 RES Since it is set close to the switching frequency F SW The normal resonant frequency F RES This embodiment is suitable for a power supply device 250 that operates at a high frequency, and the switching frequency F SW , synchronous frequency F RF , normal resonant frequency F RES Preferably, the frequency is, for example, 100 kHz or more. In addition, when the laser device 100 is a laser processing device, the output of the high frequency power supply 400 (high frequency voltage V RF ) is preferably 1 kW or more.

[0021] The damping circuit 500, which is an example of a vibration suppression circuit of the present invention, is provided between the high-frequency power supply 400 and the resonant circuit 210 (resonant inductor L), and generates a high-frequency voltage V RF The resonance frequency band of the resonant circuit 210 is defined as a frequency band that is outside the resonant frequency band of the high frequency voltage V RF , which is a frequency band that contributes to the normal resonant operation of the resonant circuit 210, and is typically a normal resonant frequency FRES The resonant frequency band is a very small frequency band centered around the synchronous frequency F RF and / or the switching frequency F SW It can also be described as a very small frequency band centered around .

[0022] The configuration of the laser cavity 200 is the same as that of Fig. 1. However, the inductor L in Fig. 1 is shown outside the laser cavity 200 as a resonant inductor L in Fig. 2.

[0023] Fig. 3 shows an example of the main circuit configuration of power supply device 250 in Fig. 2. AC-DC conversion unit 310, which receives three-phase AC from commercial power supply 10, includes a three-phase full-wave rectifier circuit 311 (three-phase bridge rectifier circuit) made up of six diodes, and a smoothing capacitor 312. Three-phase full-wave rectifier circuit 311 rectifies the input three-phase AC and converts it into a pulsating current, and smoothing capacitor 312 smoothes the pulsating current and converts it into a DC voltage.

[0024] The DC-DC conversion unit 320 includes a transistor 321 connected between a high potential line and a low potential line, an inductor 322 provided on the high potential line in front of the transistor 321, and a diode 323 provided on the high potential line in back of the transistor 321. When a PWM signal from a PWM signal generation unit 360 (not shown) is applied to a control terminal of the transistor 321, the transistor 321 performs a switching operation, and the DC-DC conversion unit 320 converts the DC voltage converted by the AC-DC conversion unit 310 into a DC voltage V suitable for laser oscillation of the laser resonator 200. DC or DC link voltage V DC Convert to.

[0025] The DC-RF conversion unit 410 in the high frequency power supply 400 includes a charging capacitor 411, an inverter 412, and a step-up transformer 413. The charging capacitor 411, also called a bank capacitor, is connected between the high potential line and the low potential line at the rear stage of the DC-DC conversion unit 320. Therefore, the charging capacitor 411 receives the DC link voltage V generated by the DC-DC conversion unit 320, which functions as a charging circuit. DCThe electrodes are charged by a DC link voltage V DC appears on the charging capacitor 411, which can also function as the DC link voltage detector 330.

[0026] The inverter 412 generates a DC voltage V between the electrodes of the charging capacitor 411. DC AC voltage V AC and applies it to a primary coil 413A of a step-up transformer 413. The inverter 412 includes a pair of transistors 412A / 412D that can pass a current through the primary coil 413A from top to bottom in FIG. 3, and a pair of transistors 412B / 412C that can pass a current through the primary coil 413A from bottom to top in FIG. 3. The high-side transistor 412A and the low-side transistor 412B are connected in series between a high-potential line and a low-potential line, and their connection point is connected to one end of the primary coil 413A of the step-up transformer 413 (the upper end in FIG. 3). Similarly, the high-side transistor 412C and the low-side transistor 412D are connected in series between a high-potential line and a low-potential line, and their connection point is connected to the other end of the primary coil 413A of the step-up transformer 413 (the lower end in FIG. 3).

[0027] A high-frequency signal generating unit 420 (not shown) applies complementary high-frequency signals to these two pairs of transistors (412A / 412D and 412B / 412C), thereby generating an AC voltage V ACSpecifically, when the high frequency signal "420" applied to the control terminal of one transistor pair 412A / 412D is "ON", the high frequency signal "420'" applied to the control terminal of the other transistor pair 412B / 412C is "OFF", and a current flows through the primary coil 413A from top to bottom in FIG. 3. Also, when the high frequency signal "420'" applied to the control terminal of the other transistor pair 412B / 412C is "ON", the high frequency signal "420" applied to the control terminal of one transistor pair 412A / 412D is "OFF", and a current flows through the primary coil 413A from bottom to top in FIG. 3. In this way, the complementary high frequency signals "420" and "420'" applied to the control terminals of the two transistor pairs have timing differences but are substantially the same switching frequency F SW It has.

[0028] The step-up transformer 413 converts the AC voltage V generated by the inverter 412 into AC is boosted to produce the high frequency voltage V RF Specifically, the AC voltage V of the primary coil 413A is generated. AC is boosted to a high-frequency voltage V RF appears in the secondary coil 413B.

[0029] The damping circuit 500 as a vibration suppression circuit is connected in parallel with the secondary coil 413B between the secondary side of the step-up transformer 413 and the resonance inductor L, and the high frequency voltage V RF The damping circuit 500 includes a resonating part 510 having a resonant frequency within the resonant frequency band, and a damping resistor 520 that attenuates the current flowing through the resonating part 510.

[0030] The resonator 510 is an LC resonator circuit including an inductor 511 and a capacitor 512 connected in parallel. The resonator 510 has a resonant frequency equal to the switching frequency F SW (Or, equivalently, the high-frequency voltage V RF The synchronous frequency F RF , the normal resonant frequency F of the resonant circuit 210RES ) is set to be approximately equal to the normal resonant frequency F RES When the device is operating normally at the normal resonant frequency F RES High frequency voltage V within the resonant frequency band centered on RF However, almost no current flows through the damping resistor 520 of the damping circuit 500.

[0031] On the other hand, in an open state due to a poor connection between the discharge electrodes 202 and 204 or in a light load state such as when the laser resonator 200 is not emitting light, the capacitance C between the discharge electrodes 202 and 204 becomes extremely small, and the normal resonant frequency F RES A significantly higher anomalous resonance frequency F RES The abnormal vibration of the high frequency voltage V RF 4 shows the high frequency voltage V when the laser resonator 200 is switched to an open load state in the power supply device 250 that does not include the damping circuit 500. RF The reference example is shown below. The load was released at the timing of "Load Released" in the center of the figure.

[0032] High frequency voltage V during normal operation before switching to the load release state RF is the normal resonant frequency F RES The example in Figure 4 shows normal oscillations at a frequency of approximately 2 MHz. On the other hand, the high-frequency voltage V RF has an abnormal resonance frequency F RES This abnormal vibration occurs when the high frequency voltage V RF Not only is the amplitude larger than that of RES ′>F RES). The influence of such high-frequency overvoltage also extends to the primary side of step-up transformer 413, and high-frequency overvoltage or overcurrent is applied to, for example, a transistor constituting inverter 412 of high-frequency power supply 400. This poses a risk of transistor malfunction or breakdown due to a surge. Furthermore, such high-frequency abnormal vibrations caused by sudden load fluctuations cannot be sufficiently suppressed by feedback control in DC power supply 300, which has a relatively large time constant due to the inclusion of an LC filter (for example, inductor 322 and smoothing capacitor 312 in FIG. 3).

[0033] In contrast to this, the power supply device 250 according to this embodiment, which is provided with the damping circuit 500, can effectively suppress abnormal vibrations after switching to the load-release state, as shown in FIG. 5. This is because the abnormal resonance frequency F RES This is because the abnormal vibration of V' passes through the resonant section 510 of the damping circuit 500, flows through the damping resistor 520, and is consumed as Joule heat. RF The damping circuit 500 includes a resonator 510 that provides frequency selectivity by allowing only the abnormal resonance frequency F outside the normal resonance frequency band to flow through the damping resistor 520, thereby quickly suppressing only the abnormal high-frequency vibrations that occur in an open state or a light load state. RES By configuring the damping circuit 500, which can non-temporarily or steadily suppress high frequency oscillations of the DC power supply 300, using only hardware or passive elements, the overvoltage can be suppressed faster than by software control or feedback control in the DC power supply 300.

[0034] Even when the laser resonator 200 is operating normally, the high frequency voltage V RF The normal resonant frequency F RESThe harmonic components of the damping resistor 520 pass through the resonator 510 of the damping circuit 500 and continue to flow through the damping resistor 520. This raises concerns about a temperature rise in the damping resistor 520. While it is possible to increase the size of the damping resistor 520 in order to suppress the temperature rise, this may result in an increase in the size of the entire power supply device 250. The laser device 100 and / or the power supply device 250 according to the second and / or third embodiments of the present invention described below can also solve this problem.

[0035] FIG. 6 is a functional block diagram of a laser apparatus 100 according to a second embodiment of the present invention. Components similar to those in the previous embodiments are designated by the same reference numerals, and redundant description will be omitted. The laser apparatus 100 in FIG. 6 includes a clamp circuit 600 instead of the damping circuit 500 of the laser apparatus 100 in FIG. 2. Furthermore, some of the software control or feedback control functions of the DC power supply 300 in FIG. 2 have been transferred to a high-frequency power supply 400 in FIG. 6. Specifically, functions similar to those of the high-frequency voltage command calculation unit 340 of the DC power supply 300 in FIG. 2 have been transferred to the high-frequency power supply 400 as a high-frequency voltage detection unit 430, a high-frequency voltage calculation unit 440, a high-frequency voltage command calculation unit 450, a control parameter determination unit 460, and the like. The DC power supply 300 in FIG. 6 includes a DC link voltage command unit 370 instead of the high-frequency voltage command calculation unit 340 in FIG. 2.

[0036] The DC link voltage command unit 370 controls the DC link voltage V DC Typically, the DC link voltage command generated by the DC link voltage command unit 370 is constant. The duty determination unit 350 generates a command for the DC link voltage V detected by the DC link voltage detection unit 330. DCIn order to reduce the deviation of the constant DC link voltage command generated by the DC link voltage command unit 370, the PWM signal generation unit 360 determines the duty ratio of the PWM signal (pulse wave) to be generated. The PWM signal generation unit 360 generates a PWM signal having the duty ratio determined by the duty determination unit 350 and applies it to the switching element (transistor 321) of the DC-DC conversion unit 320. As described above, in the DC power supply 300 of this embodiment, the DC link voltage V generated by the DC-DC conversion unit 320 DC Simple control is performed to keep the temperature constant.

[0037] The high frequency power supply 400 includes a high frequency voltage detection unit 430, a high frequency voltage calculation unit 440, a high frequency voltage command calculation unit 450, and a control parameter determination unit 460 in addition to the DC-RF conversion unit 410 and high frequency signal generation unit 420 in FIG.

[0038] The high frequency voltage detection unit 430 detects the high frequency voltage V generated by the DC-RF conversion unit 410. RF and feeds it back to the control parameter determination unit 460. Specifically, the high frequency voltage detection unit 430 detects the AC voltage V AC and / or the high frequency voltage V on the secondary side (secondary coil 413B) RF The high frequency voltage calculation unit 440 detects the AC voltage V detected by the high frequency voltage detection unit 430. AC and / or high frequency voltage V RF The high frequency voltage V generated by the DC-RF conversion unit 410 is RF is calculated and fed back to the control parameter determination unit 460.

[0039] The high-frequency voltage command calculation unit 450 calculates the high-frequency voltage V that the high-frequency power supply 400 should generate based on feedback of information indicating the operation and / or state of the laser resonator 200. RFExamples of information fed back from the laser resonator 200 to the high-frequency voltage command calculation unit 450 include the intensity of the laser light oscillated by the laser resonator 200, and the current flowing through the pair of discharge electrodes 202, 204 and / or the resonance inductor L.

[0040] The control parameter determination unit 460 determines the high frequency voltage V provided from the high frequency voltage detection unit 430 and / or the high frequency voltage calculation unit 440. RF Based on the high-frequency voltage command calculated by the high-frequency voltage command calculation unit 450, the high-frequency signal generation unit 420 determines control parameters for the high-frequency signal to be generated. Examples of these control parameters include the duty ratio and / or phase of the high-frequency signal, which is a pulse wave. When the control parameter determination unit 460 determines or adjusts the duty ratio of the high-frequency signal, the high-frequency signal generation unit 420 performs PWM control on the inverter 412 of the DC-RF conversion unit 410. When the control parameter determination unit 460 determines or adjusts the phase of the high-frequency signal, the high-frequency signal generation unit 420 performs phase shift control on the inverter 412 of the DC-RF conversion unit 410. The high-frequency voltage V detected by the high-frequency voltage detection unit 430 RF The high frequency signal generating unit 420 functions as a control signal generating unit that generates a control signal for the inverter 412 based on the duty ratio and / or phase determined by the control parameter determining unit 460, and applies the high frequency signal (pulse wave) to each transistor of the inverter 412 in the DC-RF converting unit 410.

[0041] The clamp circuit 600, which is an example of the vibration suppression circuit of the present invention, is provided between the high-frequency power supply 400 (DC-RF conversion unit 410) and the resonant circuit 210 (resonant inductor L), and applies the high-frequency voltage V RF The clamp circuit 600 suppresses vibration outside the resonant frequency band of the resonant circuit 210. The specific configuration and operation will be described later. RF is limited (clamped) within a predetermined range.

[0042] 7 shows an example of the main circuit configuration of power supply device 250 in FIG. 6. Clamp circuit 600, which serves as a vibration suppression circuit, is connected in parallel with secondary coil 413B between the secondary side of step-up transformer 413 and resonance inductor L, and is also connected to charging capacitor 411 on the primary side of step-up transformer 413 via transformer 620, etc. High-frequency voltage V appearing in secondary coil 413B RF The clamp circuit 600, which suppresses vibrations outside the resonant frequency band in the frequency domain, comprises a resonant section 610 having a resonant frequency within the resonant frequency band, a transformer 620 arranged in parallel with the step-up transformer 413, a rectifier circuit 630 connected to the high-frequency power supply 400 side of the transformer 620 (the primary side of the step-up transformer 413) and capable of charging the charging capacitor 411, and a capacitor 640 arranged in parallel with the charging capacitor 411 between the rectifier circuit 630 and the charging capacitor 411.

[0043] The resonator 610 is an LC resonator circuit including an inductor 611 and a capacitor 612 connected in parallel. Similar to the resonator 510 in FIG. 3, the resonator 610 receives a high-frequency voltage V that is substantially outside the resonant frequency band. RF This frequency selectivity allows only the normal resonant frequency F RES When the device is operating normally at the normal resonant frequency F RES High frequency voltage V within the resonant frequency band centered on RF On the other hand, when the discharge electrodes 202 and 204 are in an open state due to poor connection or the like, or when the laser resonator 200 is in a light load state such as when it is not emitting light, the high frequency voltage V RF Abnormal resonance frequency F appears in RES Abnormal vibration of the transformer 620, the rectifier circuit 630, the capacitor 640, the charging capacitor 411, etc. is quickly suppressed. As will be described later, the transformer 620, the rectifier circuit 630, the capacitor 640, the charging capacitor 411, etc. RF can be limited to within a predetermined range, so that overvoltage caused by a sudden load change can be effectively suppressed even without providing a resonating unit 610 that provides frequency selectivity.

[0044] The transformer 620 outputs a high-frequency voltage V outside the resonant frequency band through the resonant section 610. RF The first coil 621 on the secondary side of the step-up transformer 413 is supplied with the high-frequency voltage V RF The transformer 620 has a second coil 622 on the primary side of the step-up transformer 413, from which a transformed voltage of the first coil 621 appears. The transformation ratio of the transformer 620 is proportional to the turn ratio N of the first coil 621 and the second coil 622. The transformed high frequency voltage V RF The rectifier circuit 630 to which the current is supplied is a two-phase full-wave rectifier circuit (two-phase bridge rectifier circuit) consisting of four diodes. The current rectified by the rectifier circuit 630 charges the capacitor 640 and the charging capacitor 411, which are connected in parallel. As described above, the DC link voltage V DC is controlled to a constant value based on the DC link voltage command from the DC link voltage command unit 370. Therefore, even if the charging capacitor 411 is momentarily overcharged by the feedback current from the clamp circuit 600, the inter-electrode voltage is quickly restored to a constant DC link voltage V DC converges to.

[0045] The clamp circuit 600 configured as described above is a so-called regenerative voltage clamp circuit. The condition for the clamp circuit 600 to perform a regenerative operation (an operation of feeding back a voltage and / or a current from the first coil 621 to the second coil 622 of the transformer 620) is that the high-frequency voltage V RF , the DC link voltage V of the charging capacitor 411 to which feedback is DC , "V RF >N×V DC That is, the high frequency voltage V that appears on the secondary side of the step-up transformer 413 RF The amplitude of "N × V DC ", the clamp circuit 600 performs a regenerative operation to generate the high frequency voltage V RF The amplitude of "N × V DC " or less (clamp).

[0046] FIG. 8 shows the high frequency voltage V when the laser resonator 200 is switched to an open load state in the power supply device 250 provided with the clamp circuit 600. RF The abnormal resonance frequency F RES Although small abnormal vibrations due to the voltage drop due to the voltage drop are observed, it can be seen that the amplitude of the abnormal vibrations is effectively suppressed by the clamp circuit 600. The reason why the amplitude of the abnormal vibrations is suppressed so quickly is that feedback control is performed not through the DC power supply 300 that includes an LC filter with a large time constant (for example, the inductor 322 and smoothing capacitor 312 in FIG. 7), but through the clamp circuit 600 and high-frequency power supply 400 of a first-order delay system in which the main delay element is essentially only the leakage inductance of the transformer 620. In this embodiment, the DC link voltage V of the charging capacitor 411, which is the feedback control target, is DC Since the voltage Vcc is kept constant, it is possible to insert the clamp circuit 600 having the above-described configuration and function.

[0047] Here, as shown in FIG. 7 , by adopting a capacitor input system in which a capacitor 640 is provided in front of the rectifier circuit 630 of the clamp circuit 600 (on the high-frequency power supply 400 side), the time constant that causes control delay can be minimized or optimized. However, as long as the control delay is tolerable, the rectifier circuit 630 may be configured using other methods, such as a choke input system. Furthermore, to reduce control delay, it is preferable to form at least some of the semiconductor elements of the clamp circuit 600 and / or the vibration suppression circuit using wide-bandgap semiconductors such as SiC and GaN, which are capable of high-speed operation. However, as long as the control delay is tolerable, all or some of the semiconductor elements of the clamp circuit 600 and / or the vibration suppression circuit may be formed using a general-purpose semiconductor material such as Si.

[0048] In this embodiment, the damping resistor 520 has a normal resonance frequency F RES Unlike the first embodiment shown in FIG. 3, in which harmonic components of V continue to flow, RF >N×V DCUnless the operating condition of "occurrence of overvoltage" is satisfied, no current actually flows through the clamp circuit 600. Therefore, the same problem as the temperature rise of the damping resistor 520 in the first embodiment does not occur in this embodiment. Also, in this embodiment, as in the first embodiment, an abnormal resonance frequency F outside the normal resonance frequency band is RES By configuring the clamp circuit 600, which can non-temporarily or steadily suppress high frequency oscillations of the voltage drop, using only hardware or passive elements, the overvoltage can be suppressed at high speed.

[0049] FIG. 9 is a functional block diagram of a laser device 100 according to a third embodiment of the present invention. Components similar to those in the previous embodiments are designated by the same reference numerals, and redundant description will be omitted. The laser device 100 in FIG. 9 differs from the laser device 100 in FIG. 6 in the configuration of the DC power supply 300. Specifically, as shown in the main circuit configuration example in FIG. 10, the AC-DC conversion unit 310 is configured with a three-phase PFC (Power Factor Correction) circuit 313 consisting of six transistors, instead of the three-phase full-wave rectifier circuit 311 in FIG. 7. Because the three-phase PFC circuit 313 can generate a DC voltage of sufficient magnitude, the DC-DC conversion unit 320 (transistor 321, etc.) shown in FIGS. 6 and 7 is unnecessary, and an LC filter 380 consisting of a smoothing capacitor 312 and an inductor 322 is arranged downstream of the three-phase PFC circuit 313.

[0050] The present invention has been described above based on the embodiments. Various modifications are possible to the combinations of the components and processes in the exemplary embodiments, and it will be obvious to those skilled in the art that such modifications are included within the scope of the present invention.

[0051] The configuration, operation, and function of each device and method described in the embodiments can be realized by hardware resources, software resources, or a combination of hardware and software resources. Examples of hardware resources include processors, ROMs, RAMs, and various integrated circuits. Examples of software resources include operating systems, applications, and other programs. [Explanation of symbols]

[0052] 100 laser device, 200 laser resonator, 202 discharge electrode, 204 discharge electrode, 210 resonant circuit, 250 power supply device, 300 DC power supply, 400 high frequency power supply, 410 DC-RF conversion unit, 411 charging capacitor, 412 inverter, 413 step-up transformer, 420 high frequency signal generation unit, 430 high frequency voltage detection unit, 500 damping circuit, 510 resonant unit, 520 damping resistor, 600 clamp circuit, 610 resonant unit, 620 transformer, 630 rectifier circuit, 640 capacitor.

Claims

1. A power supply device for driving a laser resonator including a pair of discharge electrodes, a high frequency power supply that applies a high frequency voltage to a resonant circuit including the capacitance of the pair of discharge electrodes; a vibration suppression circuit provided between the high frequency power supply and the resonant circuit, for suppressing vibrations of the high frequency voltage outside a resonant frequency band of the resonant circuit; Equipped with the vibration suppression circuit is a clamp circuit that limits the high-frequency voltage within a predetermined range, the high-frequency power supply includes a charging capacitor that is charged by a charging circuit, an inverter that converts a DC voltage of the charging capacitor into an AC voltage, and a step-up transformer that boosts the AC voltage to generate the high-frequency voltage; The clamp circuit is a power supply device including: a transformer provided in parallel with the step-up transformer; and a rectifier circuit connected to the high-frequency power supply side of the transformer and capable of charging the charging capacitor.

2. the high-frequency power supply includes an inverter that converts a supplied DC voltage into an AC voltage, and a step-up transformer that boosts the AC voltage to generate the high-frequency voltage; the vibration suppression circuit is connected between the secondary side of the step-up transformer and the resonant circuit. The power supply device of claim 1 .

3. 2. The power supply device according to claim 1, wherein the vibration suppression circuit is a damping circuit including a resonant part having a resonant frequency within the resonant frequency band, and a damping resistor that attenuates a current flowing through the resonant part.

4. 2. The power supply device according to claim 1, wherein the clamp circuit comprises a capacitor provided between the rectifier circuit and the charging capacitor and in parallel with the charging capacitor.

5. 2. The power supply device according to claim 1, wherein the high frequency power supply comprises: a high frequency voltage detector that detects the high frequency voltage; and a control signal generator that generates a control signal for the inverter based on the high frequency voltage.

6. a laser resonator including a pair of discharge electrodes; a high frequency power supply that applies a high frequency voltage to a resonant circuit including the capacitance of the pair of discharge electrodes; a vibration suppression circuit provided between the high frequency power supply and the resonant circuit, for suppressing vibrations of the high frequency voltage outside a resonant frequency band of the resonant circuit; Equipped with the vibration suppression circuit is a clamp circuit that limits the high-frequency voltage within a predetermined range, the high-frequency power supply includes a charging capacitor that is charged by a charging circuit, an inverter that converts a DC voltage of the charging capacitor into an AC voltage, and a step-up transformer that boosts the AC voltage to generate the high-frequency voltage; The clamp circuit is a laser device including a transformer provided in parallel with the step-up transformer, and a rectifier circuit connected to the high-frequency power supply side of the transformer and capable of charging the charging capacitor.

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