Power supply unit, inverter unit

Abstract

To provide a power supply device and the like capable of reducing a loss even at a low load.SOLUTION: A power supply device that drives a laser resonator including a pair of discharge electrodes, comprises: an inverter that comprises at least two switching elements connected in series between a high potential line and a low potential line to convert a DC voltage between the high potential line and the low potential line into an AC voltage by switching control of each switching element and apply the AC voltage from a connection point of each switching element to the pair of discharge electrodes; and a control signal application part that can apply to a control terminal of at least one switching element a control signal which takes an ON level VON which can turn ON the switching element, an OFF level VOFF which can turn OFF the switching element, and an intermediate level VM between the ON level VON and the OFF level VOFF which can at least partially turn ON the switching element.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] This invention relates to a power supply device, etc. [Background technology]

[0002] Laser processing equipment is widely used as an industrial processing tool. High-power gas lasers, such as CO2 lasers, are used in laser processing equipment. Figure 1 is a functional block diagram of a laser processing equipment or laser device 100R. Laser device 100R comprises a laser resonator 200 and a power supply unit 250R. The laser resonator 200 comprises a pair of discharge electrodes 202 and 204, a total reflection mirror 206, and a partial reflection mirror 208.

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

[0004] The power supply unit 250R that drives the laser resonator 200 uses a high-frequency voltage V RF The high-frequency voltage V is applied to the resonant circuit 210. RF Frequency F RF (Hereafter also referred to as the synchronization frequency) is the resonant frequency F of the resonant circuit 210. RES It is set in the vicinity of the high-frequency voltage V. RF When a current is applied, a discharge current flows between the pair of discharge electrodes 202 and 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 reflection mirror 206 and the partial reflection mirror 208, and is amplified as it passes through the excited laser medium gas. A portion of the amplified stimulated emission light is extracted from the partial reflection mirror 208 as output (laser light).

[0005] The power supply unit 250R provides a stabilized DC voltage V DCA DC power supply 300 that generates, and a DC voltage V DC is converted into a high-frequency voltage V RF and includes a high-frequency power supply 400 that applies it to the resonance circuit 210. The high-frequency power supply 400 has a DC voltage V DC is converted into a high-frequency voltage V that is an AC voltage RF An inverter for conversion is provided. A general inverter includes one or more transistor pairs that are complementarily switched and controlled. Each transistor is switched between an on state and an off state, for example, by a PWM (Pulse Width Modulation) signal as a control signal.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] When the load of the laser resonator 200 is small, the high-frequency voltage V can be reduced by reducing the duty ratio of the PWM signal RF . However, as a result of the inventor's own study, particularly when the load of the laser resonator 200 is small, due to the influence of a control signal that abruptly switches between an off level and an on level, a phenomenon was confirmed in which a transistor that should be in an off state accidentally turns on. As a result, both the high-potential side transistor and the low-potential side transistor constituting the transistor pair are turned on, and a current instantaneously flows between the high-potential line and the low-potential line that supply the DC voltage V DC and a large loss occurs.

[0008] The present invention has been made in view of such a situation, and an object thereof is to provide a power supply device and the like that can reduce losses even at low loads.

Means for Solving the Problems

[0009] To solve the above problems, a power supply device in one aspect of the present invention is a power supply device for driving a laser resonator including a pair of discharge electrodes, comprising: an inverter that converts the DC voltage between the high-potential line and the low-potential line into an AC voltage by switching control of each switching element and applies it to the pair of discharge electrodes from the connection point of each switching element; and a control signal application unit that can apply a control signal to the control terminal of at least one switching element, which takes the following levels: an on-level when the switching element is turned on, an off-level when the switching element is turned off, and an intermediate level between the on-level and the off-level when the switching element is at least partially turned on.

[0010] In this embodiment, the control signal applied to the control terminal of the switching element in the inverter can take an intermediate level between the off-level and the on-level. As a result, the change in the control signal during the transition between the off-level and the on-level becomes gradual, effectively preventing transistors that should be in the off-level from mistakenly becoming on-level. Therefore, this power supply device can reduce losses even at low loads.

[0011] Another aspect of the present invention is an inverter device. This device comprises an inverter that includes at least two switching elements connected in series between a high-potential line and a low-potential line, and converts the DC voltage between the high-potential line and the low-potential line into an AC voltage by switching control of each switching element and outputs it from the connection point of each switching element, and a control signal application unit that can apply a control signal to the control terminal of at least one switching element, which takes the following levels: an on-level when the switching element is turned on, an off-level when the switching element is turned off, and an intermediate level between the on-level and the off-level when the switching element is at least partially turned on.

[0012] Furthermore, any combination of the above components, as well as methods, apparatus, systems, recording media, computer programs, etc., derived from these representations, are also included in the present invention. [Effects of the Invention]

[0013] According to the present invention, losses can be reduced even under low load conditions. [Brief explanation of the drawing]

[0014] [Figure 1] This is a functional block diagram of the laser device. [Figure 2] This is a functional block diagram of the laser device. [Figure 3] Figure 2 shows an example of the main circuit configuration of the power supply unit. [Figure 4] A schematic example of inverter phase shift control is shown (under light load conditions). [Figure 5] A schematic example of inverter phase shift control is shown (under heavy load). [Figure 6] This shows an example of the voltage that appears between the gate and source of a transistor pair under light load conditions. [Figure 7] This example shows the relationship between the amount of phase shift and the losses generated in the inverter. [Figure 8] A convex control signal is schematically shown. [Figure 9] A schematic example of inverter phase shift control is shown (under light load conditions). [Figure 10] This shows an example of the voltage that appears between the gate and source of a transistor pair under light load conditions. [Figure 11] This example shows the relationship between the amount of phase shift and the losses generated in the inverter. [Figure 12] This is the first variation of the control signal that takes an intermediate level. [Figure 13] This is a second variation of the control signal that takes an intermediate level. [Modes for carrying out the invention]

[0015] The following describes in detail embodiments (hereinafter also referred to as "models") for carrying out the present invention, with reference to the drawings. In the description and / or drawings, identical or equivalent components, members, processes, etc., are denoted by the same reference numerals, and redundant descriptions are omitted. The scale and shape of each part shown in the drawings are set for convenience to simplify the description and are not to be interpreted restrictively unless otherwise specified. The embodiments are illustrative and do not limit the scope of the present invention in any way. Not all features or combinations thereof described in the embodiments are necessarily essential to the present invention.

[0016] Figure 2 is a functional block diagram of a laser device 100 according to an embodiment of the present invention. The laser device 100 comprises a commercial power supply 10, a DC power supply 300, a high-frequency power supply 400, a resonant inductor L, and a laser resonator 200. The configuration of the laser resonator 200 is the same as in Figure 1. However, the inductor L in Figure 1 is shown as a resonant inductor L outside the laser resonator 200 in Figure 2.

[0017] The power supply unit 250 is composed of a DC power supply 300 and a high-frequency power supply 400. Functional blocks of the power supply unit 250 that involve software control are realized through the collaboration of hardware resources such as the computer's central processing unit, memory, input devices, output devices, and peripheral devices connected to the computer, and the software that runs using them. Regardless of the type or location of the computer, each of the above functional blocks may be realized using the hardware resources of a single computer, or it may be realized by combining hardware resources distributed across multiple computers.

[0018] The DC power supply 300 comprises an AC-DC converter 310, an LC filter 320, and a DC link voltage detection unit 330. The AC-DC converter 310 converts an AC voltage, such as a three-phase AC, supplied from the commercial power supply 10 into a DC voltage. The LC filter 320 is a low-pass or band-pass filter including an inductor (L) and a capacitor (C), and removes mainly high-frequency components contained in the DC voltage converted by the AC-DC converter 310, thereby smoothing it. In the following, the DC voltage smoothed by the LC filter 320 is referred to as the DC voltage V DC DC link voltage V DC It can also be expressed as follows. The DC link voltage detection unit 330 detects the DC link voltage V generated by the LC filter 320. DC The DC link voltage V generated by the LC filter 320 is detected and provided to the phase shift amount determination unit 460, which will be described later. DC This, along with the detection result (data) from the DC link voltage detection unit 330, is supplied to the DC-RF conversion unit 410, which will be described later.

[0019] The high-frequency power supply 400 comprises a DC-RF conversion unit 410, a high-frequency signal generation unit 420, a high-frequency voltage detection unit 430, a high-frequency voltage calculation unit 440, a high-frequency voltage command calculation unit 450, and a phase shift amount determination unit 460. The DC-RF conversion unit 410 generates the DC link voltage V from the DC power supply 300. DC The synchronization frequency F RF High-frequency voltage V RF Converts to a DC link voltage V. As shown in Figure 3 below, the DC-RF conversion unit 410 converts to a DC link voltage V. DC AC voltage V AC An inverter 412 that converts to the AC voltage V AC Boost the voltage to produce a high-frequency voltage V RF It includes a step-up transformer 413 that generates the voltage.

[0020] The high-frequency signal generation unit 420, which constitutes the control signal application unit, generates a high-frequency signal as a control signal for switching control of the transistor group of the inverter 412. The switching frequency F is the frequency of this high-frequency signal. SW is a high-frequency voltage V RFSynchronization frequency F RF It is essentially equivalent to this. Also, the synchronization frequency F RF The resonant frequency F of the resonant circuit 210 is RES Because it is set in the vicinity of, the switching frequency F SW The resonant frequency F RES It is set in the vicinity of. This embodiment is suitable for a power supply unit 250 that operates at a high frequency, and the switching frequency F SW , synchronization frequency F RF , resonant frequency F RES It is preferable that the frequency is, for example, 1 MHz or higher. Also, the output of the high-frequency power supply 400 (high-frequency voltage V) when the laser device 100 is a laser processing device. RF ) is preferably 1 kW or more.

[0021] The high-frequency voltage detection unit 430 detects the AC voltage V generated by the DC-RF conversion unit 410. AC and / or high-frequency voltage V RF It detects this and feeds it back to the phase shift amount determination unit 460. Specifically, the high-frequency voltage detection unit 430 detects the AC voltage V on the primary side (primary coil 413A) of the step-up transformer 413 in Figure 3. 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 Based on this, the DC-RF converter 410 generates a high-frequency voltage V RF The calculation is performed and fed back to the phase shift amount determination unit 460. The high-frequency voltage detection unit 430 detects the high-frequency voltage V RF If the voltage is detected directly, the high-frequency voltage calculation unit 440 for calculating it does not need to be provided.

[0022] The high-frequency voltage command calculation unit 450 determines, based on feedback of information indicating the operation and / or state of the laser resonator 200, the high-frequency voltage V that the high-frequency power supply 400 should generate. RFThe unit calculates commands for the following. Examples 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 resonant inductor L.

[0023] The phase shift amount determination unit 460, which together with the high-frequency signal generation unit 420 constitutes the control signal application unit, receives the high-frequency voltage V provided from the high-frequency voltage detection unit 430 and / or high-frequency voltage calculation unit 440. RF (Data) High-frequency voltage command calculated by the high-frequency voltage command calculation unit 450, DC link voltage V detected by the DC link voltage detection unit 330 DC Based on this, the high-frequency signal generation unit 420 determines the phase shift amount of the high-frequency signal to be generated. The high-frequency signal generation unit 420 generates a control signal or high-frequency signal with the phase determined by the phase shift amount determination unit 460 and applies it to each transistor of the inverter 412 of the DC-RF conversion unit 410. Details of the processing by the phase shift amount determination unit 460 and the high-frequency signal generation unit 420 will be described later.

[0024] Figure 3 shows an example of the main circuit configuration of the power supply unit 250 (especially the high-frequency power supply 400) shown in Figure 2. 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 40H and the low-potential line 40L after the LC filter 320 (not shown in Figure 3). Therefore, the charging capacitor 411 receives the DC link voltage V generated by the AC-DC conversion unit 310 and the LC filter 320, which function as a charging circuit. DC It is charged by a DC link voltage V between the electrodes. DC The charging capacitor 411, which appears as a result, can also function as a DC link voltage detection unit 330.

[0025] The inverter 412 controls the DC voltage V between the electrodes of the charging capacitor 411. DC AC voltage V ACThe voltage is converted to and applied to the primary coil 413A of the step-up transformer 413. The inverter 412 includes at least two switching elements connected in series between the high-potential line 40H and the low-potential line 40L, and the DC voltage between the high-potential line 40H and the low-potential line 40L is controlled by the switching control of each of these switching elements by the high-frequency signal generation unit 420. DC AC voltage V AC The voltage is converted and applied from the connection point of each switching element to a pair of discharge electrodes 202 and 204 of the laser resonator 200 via a step-up transformer 413. In this embodiment, the switching elements in the inverter 412 are composed of transistors 412A to 412D. The types of transistors 412A to 412D are arbitrary and may be field-effect transistors (FETs), bipolar transistors, or insulated-gate bipolar transistors (IGBTs).

[0026] In the example shown in Figure 3, the inverter 412 comprises a first transistor pair 412A / 412B, which is a first switching element pair consisting of a first high-potential side transistor 412A as a first high-potential side switching element and a first low-potential side transistor 412B as a first low-potential side switching element, connected in series between the high-potential line 40H and the low-potential line 40L; and a second transistor pair 412C / 412D, which is a second switching element pair consisting of a second high-potential side transistor 412C as a second high-potential side switching element and a second low-potential side transistor 412D as a second low-potential side switching element, connected in series between the high-potential line 40H and the low-potential line 40L. The connection point (midpoint) between the first high-potential side transistor 412A and the first low-potential side transistor 412B is connected to one end (upper end in Figure 3) of the primary coil 413A of the step-up transformer 413. Similarly, the connection point (midpoint) between the second high-potential transistor 412C and the second low-potential transistor 412D is connected to the other end (lower end in Figure 3) of the primary coil 413A of the step-up transformer 413.

[0027] The high-frequency signal generation unit 420 (Figure 2) applies complementary high-frequency signals to these two sets of transistor pairs (412A / 412B and 412C / 412D), thereby generating an AC voltage V in the primary coil 413A of the step-up transformer 413. AC This generates a specific high-frequency signal. Specifically, when the high-frequency signal applied to the control terminal of one transistor in the first transistor pair 412A / 412B is "ON", the high-frequency signal applied to the control terminal of the other transistor is "OFF". In other words, the first transistor pair 412A / 412B is controlled so that they are never "ON" at the same time. In Figure 3, the input to the control terminal of the first high-potential side transistor 412A is shown as "420", while the input to the control terminal of the first low-potential side transistor 412B is shown as "420'", which is for convenience only.

[0028] Similarly, when the high-frequency signal applied to the control terminal of one transistor in the second transistor pair 412C / 412D is "ON", the high-frequency signal applied to the control terminal of the other transistor is "OFF". In other words, the second transistor pair 412C / 412D is controlled so that they are never "ON" at the same time. In Figure 3, the input to the control terminal of the second high-potential side transistor 412C is shown as "420'", while the input to the control terminal of the second low-potential side transistor 412D is shown as "420", which is for convenience only.

[0029] As indicated by the same symbol "420" in Figure 3, the control terminals of the first high-potential transistor 412A and the second low-potential transistor 412D are applied by the high-frequency signal generation unit 420 to control signals such that each transistor 412A and 412D is simultaneously "ON". However, as will be described later, the phase of each control signal is shifted (out of phase) based on the phase shift amount determined by the phase shift amount determination unit 460. While transistors 412A and 412D are simultaneously "ON", transistors 412B and 412C, which are controlled complementary to them, are "OFF", and current flows from top to bottom in the primary coil 413A in Figure 3.

[0030] Similarly, as indicated by the same symbol "420'" in Figure 3, the control terminals of the first low-potential transistor 412B and the second high-potential transistor 412C are applied by the high-frequency signal generation unit 420 to control signals such that each transistor 412B and 412C is simultaneously "ON". However, as will be described later, the phase of each control signal is shifted (out of phase) based on the phase shift amount determined by the phase shift amount determination unit 460. While transistors 412B and 412C are simultaneously "ON", transistors 412A and 412D, which are controlled complementary to them, are "OFF", and current flows from bottom to top in the primary coil 413A in Figure 3.

[0031] The step-up transformer 413 outputs the AC voltage V generated by the inverter 412. AC Boost the voltage to produce a high-frequency voltage V RF It generates the AC voltage V of the primary coil 413A. AC The boosted high-frequency voltage V RF This appears in the secondary coil 413B.

[0032] Figures 4 and 5 schematically show an example of phase shift control of the inverter 412 by the phase shift amount determination unit 460 and the high-frequency signal generation unit 420, which constitute the control signal application unit. Figure 4 shows the case when the load on the laser resonator 200 is relatively light, and Figure 5 shows the case when the load on the laser resonator 200 is relatively heavy.

[0033] The phase shift amount determination unit 460 changes at least one of the following periods according to the load of the laser resonator 200: a first overlap period (represented by the first and third "φ" from the left in Figures 4 and 5) in which the first high-potential gate signal Ga, which is the first high-potential control signal applied to the gate of the first high-potential transistor 412A, and the second low-potential gate signal Gd, which is the second low-potential control signal applied to the gate of the second low-potential transistor 412D, are both on level; and a second overlap period (represented by the second and fourth "φ" from the left in Figures 4 and 5) in which the second high-potential gate signal Gc, which is the second high-potential control signal applied to the gate of the second high-potential transistor 412C, and the first low-potential gate signal Gb, which is the first low-potential control signal applied to the gate of the first low-potential transistor 412B, are both on level.

[0034] Furthermore, the phase shift amount determination unit 460 changes the first overlap period by changing the relative phase of the first high-potential gate signal Ga and the second low-potential gate signal Gd, which have substantially the same waveform (rectangular in Figures 4 and 5), and / or changes the second overlap period by changing the relative phase of the second high-potential gate signal Gc and the first low-potential gate signal Gb, which have substantially the same waveform (rectangular in Figures 4 and 5).

[0035] Specifically, the phase shift amount determination unit 460 makes the phase shift amount represented by "φ" relatively small under light load conditions as shown in Figure 4, and makes the phase shift amount represented by "φ" relatively large under heavy load conditions as shown in Figure 5. As a result, under light load conditions as shown in Figure 4, the first overlap period (where both transistor pairs 412A and 412D are ON and a positive AC voltage V) is equivalent to the phase shift amount φ. AC(a negative AC voltage is generated) and / or during the second overlapping period (when both transistors 412B / 412C are turned on and a negative AC voltage V AC The time it takes for the generated voltage to be relatively short. As shown in Figure 4, the positive and negative AC voltages V AC Because the duration is relatively short, the high-frequency voltage V ultimately generated via the step-up transformer 413 RF The amplitude of is reduced in accordance with the light load on the laser resonator 200. Similarly, under heavy load conditions as shown in Figure 5, the first and / or second overlap periods, which are equivalent to the phase shift amount φ, become relatively long. As shown in Figure 5, the "positive" and "negative" AC voltages V AC Because the duration is relatively long, the high-frequency voltage V is ultimately generated via the step-up transformer 413. RF The amplitude is increased in accordance with the heavy load on the laser resonator 200.

[0036] In Figures 4 and 5, the phase shift amount φ is assumed to be uniform for convenience, but each phase shift amount φ is independently determined by the phase shift amount determination unit 460 (where 0 ≤ φ ≤ 180). Therefore, the lengths of the first and second overlap periods, which are determined by the phase shift amount φ, are also variable by the phase shift amount determination unit 460. When the load on the laser resonator 200 is stable, it is preferable to make the lengths of the first and second overlap periods substantially equal by keeping the phase shift amount φ constant, as shown in Figures 4 and 5.

[0037] Figure 6 shows an example of the voltages that appear between the gate / source of the high-potential side transistor (412A or 412C) and the low-potential side transistor (412B or 412D) in the first transistor pair 412A / 412B or the second transistor pair 412C / 412D under light load conditions as shown in Figure 4. The switching frequency F in this example is shown. SW The frequency is 2 MHz. The solid line represents the gate / source voltage of the high-potential transistor, and the dashed line represents the gate / source voltage of the low-potential transistor.

[0038] As mentioned above, each transistor pair is controlled so that they do not turn on simultaneously. However, in the transition period T1 shown in Figure 6, when the low-potential transistor transitions from the off state to the on state, the high-potential transistor, which should normally remain in the off state, momentarily transitions to the on state. Furthermore, when the high-potential transistor momentarily turns on, the gate / source voltage of the low-potential transistor momentarily drops, causing it to transition to the off state. Similarly, in the transition period T2 shown in Figure 6, when the high-potential transistor transitions from the off state to the on state, the low-potential transistor, which should normally remain in the off state, momentarily transitions to the on state. Furthermore, when the low-potential transistor momentarily turns on, the gate / source voltage of the high-potential transistor momentarily drops, causing it to transition to the off state.

[0039] This undesirable behavior of the inverter 412 under light load conditions is due to the load current I flowing through the laser resonator 200. RF This is because, under light load conditions, the voltage becomes smaller, and as a result, the following ZVS (Zero Voltage Switching) conditions are no longer met, causing inverter 412 to enter a so-called hard-switching state. I RF ≥V DC ×√(2×C OSS / L leak ) Here, C OSS L is the output capacitance of switching elements such as transistors 412A to 412D. leak This is the leakage inductance of the step-up transformer 413.

[0040] In a hard-switching state, the voltage and current change abruptly when the transistors are switched on or off, resulting in large switching losses. Furthermore, in this embodiment, the inverter 412, which is preferably operated in a high-frequency band of 1 MHz or higher, experiences a large change in the rate of change (time derivative) of the drain / source current of each transistor 412A to 412D when in a hard-switching state. As a result, each transistor 412A to 412D mistakenly transitions to the ON state instantaneously, as shown in Figure 6 (hereinafter also referred to as "gate misfiring" or "misfiring").

[0041] Figure 7 shows an example of the relationship between the phase shift amount φ determined by the phase shift amount determination unit 460 and the losses generated in the inverter 412. As mentioned above, the phase shift amount φ correlates with the load of the laser resonator 200, so the left side of this figure, where the phase shift amount φ is small, corresponds to a light load state. In this example, it can be seen that when the phase shift amount φ is 40 degrees or less under light load conditions, gate misfires like those in Figure 6 occur frequently, and the losses in the inverter 412 become significantly larger.

[0042] To suppress the undesirable behavior of the inverter 412 under light load conditions as described above, the high-frequency signal generation unit 420 can apply a convex control signal (gate signals Ga to Gd), schematically shown in Figure 8, to the gate of at least one transistor 412A to 412D of the inverter 412, instead of the rectangular control signal (gate signals Ga to Gd) shown in Figures 4 and 5.

[0043] This control signal is an on-level V signal that turns on transistors 412A to 412D. ON At this point, transistors 412A to 412D turn off, reaching an off-level V. OFF Then, at an on-level V, transistors 412A to 412D are at least partially turned on. ON and off-level V OFF Intermediate level V between M It essentially takes three different voltage levels. Specifically, the voltage level of the control signal in the example in Figure 8 is the off-level V OFF From intermediate level V Mtransitions to the intermediate level V M and then from the intermediate level V ON to the on level V ON and then from the on level V M to the intermediate level V M and then from the intermediate level V OFF to the off level V. The intermediate level V M is set to be greater than the threshold voltage V TH of the transistors 412A to 412D. Therefore, the transistors 412A to 412D to which the control signal of the intermediate level V M is applied are at least partially in the on state. Thus, the transistors 412A to 412D are at least partially in the on state during the on period T M when the control signal of the intermediate level V ON or the on level V ON is applied.

[0044] In the rectangular control signals in FIGS. 4 and 5, the control signal of the on level V ON is continuously applied to the transistors 412A to 412D during the on period T ON having substantially the same length as that in FIG. 8. In contrast, in the convex control signal in FIG. 8, at the start of the on period T ON the voltage level gradually increases from the off level V OFF through the intermediate level V M to the on level V ON and at the end of the on period T ON the voltage level gradually decreases from the on level V<{ ON through the intermediate level V M to the off level V OFF . Thus, according to the control signal having the intermediate level V M as shown in FIG. 8, the change rate (time derivative coefficient) of the drain / source current of each of the transistors 412A to 412D can be made smaller than that of the rectangular control signals in FIGS. 4 and 5, and thus the error arcs of each of the transistors 412A to 412D can be suppressed as will be described later with respect to FIG. 10.

[0045] When the control signal transitions from the off level V OFF to the on level V ONWhen transitioning to (on period T) ON Intermediate level V (at the start) M The first intermediate period T M1 The length and the on-level V control signal ON From off-level V OFF When transitioning to (on period T) ON Intermediate level V (at the end) M The second midterm period T M2 The lengths may be different, but it is preferable that they be substantially equal (hereinafter referred to as the first intermediate period T) M1 and the second interim period T M2 Intermediate period T M (collectively referred to as ). As shown in Figure 9 below, the intermediate period T M The length of the intermediate period T can be arbitrarily set within a range less than or equal to the phase shift amount φ (length of the first overlap period and / or second overlap period) determined by the phase shift amount determination unit 460. M The length of the interval can be made larger than the phase shift amount φ, but the transistor pairs 412A / 412D and 412B / 412C are in a conductive state during the first overlap period and the second overlap period determined by the phase shift amount φ, so the intermediate period T M Making the length larger than the phase shift amount φ does not yield any practical effect.

[0046] Furthermore, in at least one transistor 412A to 412D, the intermediate level V M A rectangular control signal, as shown in Figures 4 and 5, which does not take a specific shape, may be used, or the first intermediate period T may be used. M1 and the second interim period T M2 A control signal may be used in which one side is not provided and only the other side is stepped, or the first intermediate period T M1 Intermediate level V M and the second interim period T M2 Intermediate level V M Different asymmetric control signals may be used. However, as shown in Figure 8, the first intermediate period T is equal to each other. M1 and the second interim period T M2 At the same voltage level (intermediate level V) MA symmetrical control signal that takes the following steps is highly versatile and has a small number of parameters (intermediate period T). M and intermediate level V M By simply specifying the transistor (412A~412D), flexible settings can be made to suit each transistor.

[0047] Figure 9 shows an example where, under light load conditions similar to those in Figure 4, the convex control signal (gate signals Ga to Gd) shown in Figure 8 is applied to the gates of each transistor 412A to 412D of the inverter 412, instead of the rectangular control signal (gate signals Ga to Gd) shown in Figure 4.

[0048] Similar to the example in Figure 4, the phase shift amount determination unit 460 determines when the first high-potential gate signal Ga and the second low-potential gate signal Gd are both on-level V ON or intermediate level V M During the first overlapping period (the periods represented by the first and third "φ" from the left in Figure 9), and when both the second high-potential gate signal Gc and the first low-potential gate signal Gb are on level V ON or intermediate level V M The second overlapping period (the second and fourth periods from the left represented by "φ" in Figure 9) is varied according to the load of the laser resonator 200.

[0049] Unlike Figure 4, in at least a portion of the first overlap period and / or the second overlap period, at least one gate signal Ga~Gd is at the intermediate level V M However, as mentioned above, intermediate level V M The threshold voltage V of transistors 412A to 412D TH Because it is set to a higher level, intermediate level V M When the gate signals Ga~Gd are applied, transistors 412A~412D turn ON. Therefore, as in Figure 4, during the first overlap period, both transistor pairs 412A / 412D are ON, and a positive AC voltage V AC This is generated, and in the second overlapping period, both transistor pairs 412B and 412C are turned on, resulting in a "negative" AC voltage V ACThis is generated. In this way, the output V of inverter 412 and / or high-frequency power supply 400 is generated by changing the shape of the gate signal Ga~Gd. AC and / or V RF There is no significant impact.

[0050] Figure 10, similar to Figure 6, shows examples of the gate / source voltages that appear between the high-potential side transistor (412A or 412C) and the low-potential side transistor (412B or 412D) in the example of Figure 9 under light load. Similar to Figure 6, the solid line represents the gate / source voltage of the high-potential side transistor, and the dashed line represents the gate / source voltage of the low-potential side transistor.

[0051] In Figure 10, the intermediate level V M By providing this, off-level V OFF and on-level V ON As a result of the gradual change in the gate signal Ga~Gd during the transition between these states, the gate misfires that occurred in Figure 6 are effectively suppressed. Specifically, in the transition period T1 shown in Figure 10, the low-potential side transistor transitions from the off state to the threshold voltage V TH When transitioning to a higher ON state, the gate / source voltage of the high-potential side transistor also rises slightly, but the threshold voltage V TH Since it does not exceed the threshold voltage, the high-potential side transistor is maintained in the intended off state. Similarly, during the transition period T2 shown in Figure 10, the high-potential side transistor transitions from the off state to the threshold voltage V TH When transitioning to a higher ON state, the gate / source voltage of the lower-potential side transistor also rises slightly, but the threshold voltage V TH Since the voltage does not exceed the limit, the low-potential transistor is maintained in the intended off state. In this way, by using the control signals (gate signals Ga~Gd) as shown in Figure 8, false firing of transistors 412A~412D, which is prone to occurring under light loads, can be suppressed, and the losses of the inverter 412 can be reduced.

[0052] Figure 11, similar to Figure 7, shows an example of the relationship between the phase shift amount φ determined by the phase shift amount determination unit 460 and the losses generated in the inverter 412. In this example, under heavy load conditions where the phase shift amount φ is greater than "approximately 100 degrees", the inverter 412 is in a soft switching state that satisfies the aforementioned ZVS condition, and the effect of gate misfiring can be ignored. Therefore, the rectangular control signal (gate signals Ga~Gd) shown in Figure 5 is applied to the control terminals (gates) of transistors 412A~412D. On the other hand, under light load conditions where the phase shift amount φ is "approximately 100 degrees" or less, the inverter 412 is in a hard switching state that does not satisfy the aforementioned ZVS condition, and the effect of gate misfiring cannot be ignored. Therefore, the convex control signal (gate signals Ga~Gd) shown in Figure 8 is applied to the control terminals (gates) of transistors 412A~412D. In Figure 7, when the phase shift amount φ was 40 degrees or less, gate misfires occurred frequently, and the losses of inverter 412 increased significantly. However, in Figure 11, it can be seen that the increase in losses of inverter 412 is suppressed even when the phase shift amount φ is 40 degrees or less. Thus, as shown in Figure 8, the intermediate level V M By utilizing the control signals (gate signals Ga~Gd) that take this form, gate misfires can be effectively suppressed, especially under light load conditions.

[0053] In the example in Figure 11, the control signals applied to transistors 412A to 412D were switched between a rectangular shape (Figure 5) and a convex shape (Figure 9) based on a threshold of "approximately 100 degrees" according to the ZVS condition. However, the shape of the control signals may be switched based on other thresholds. For example, a threshold may be set for the phase shift amount φ (length of the first overlap period and / or second overlap period) determined by the phase shift amount determination unit 460. For example, in the example in Figure 11, "40 degrees" may be used as the threshold, and when the phase shift amount φ is "40 degrees" or more under heavy load, the off-level V OFF and on-level V ON Using a rectangular control signal that switches between these two values, when the phase shift amount φ is less than "40 degrees" under light load conditions, the off-level V OFF Intermediate level V M On-level V ON It utilizes a convex control signal that switches between these states.

[0054] Furthermore, in order to suppress gate misfires, as explained with respect to Figure 10, the gate / source voltage of the transistor that should be kept in the off state should be the threshold voltage V TH It is sufficient if it does not exceed this value. Therefore, the gate / source voltage and threshold voltage V of each transistor TH The gate / source voltages are compared continuously or intermittently, and the gate / source voltages for the period during which each transistor should remain in the off state are compared with the threshold voltage V. TH To prevent exceeding this threshold, a threshold for the smallest possible phase shift amount φ may be adaptively set. Alternatively, without setting such a threshold, the intermediate level V shown in Figure 8 may always be maintained regardless of the phase shift amount φ or the load on the laser resonator 200. M A control signal (gate signal Ga~Gd) may be used to take this action.

[0055] Figure 12 shows the intermediate level V M This is the first variation of the control signal that takes multiple intermediate levels V. M Take the off-level V in the example in Figure 12. OFF at least one first intermediate level V on the side M1 And, on level V ON At least one second intermediate level V on the side M2 A safety feature is provided. Specifically, the voltage level of the control signal in the example in Figure 12 is the off-level V OFF From the first intermediate level V M1 It transitions to the first intermediate level V M1 From the second intermediate level V M2 It transitions to the second intermediate level V M2 From On Level V ON It transitions to the on-level V ON From the second intermediate level V M2 It transitions to the second intermediate level V M2 From the first intermediate level V M1 It transitions to the first intermediate level V M1 From off-level V OFF The transition occurs. Here, in order to turn on transistors 412A to 412D at least partially, the first intermediate level V M1 and second intermediate level VM2 In all cases, this refers to the threshold voltage V of transistors 412A to 412D. TH It will be set to a larger value.

[0056] Figure 13 shows the intermediate level V M This is a second variation of the control signal that takes a continuous intermediate level V. M Take the first intermediate level V in Figure 12. M1 and second intermediate level V M2 Numerous intermediate level V M These are provided in a substantially continuous manner. Here, the first intermediate level V M1 is an off-level V OFF On-level V before and after the switch between the two ON Although it is an endpoint that is continuously connected, the second intermediate level V M2 This is the first intermediate level V M1 and on-level V ON Numerous intermediate level V M This is just one example. The voltage level of the control signal in the example in Figure 13 is the off-level V OFF From the first intermediate level V M1 It transitions to the first intermediate level V M1 From the second intermediate level V M2 Numerous intermediate level V M via on-level V ON It transitions continuously to the on-level V ON From the second intermediate level V M2 Numerous intermediate level V M via the first intermediate level V M1 It transitions continuously to the first intermediate level V M1 From off-level V OFF It transitions to the first intermediate level V. M1 and on-level V ON The connection between them may be curved in a manner different from that shown in Figure 13, or it may be straight.

[0057] The present invention has been described above based on embodiments. Various modifications are possible for each component and each combination of 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.

[0058] In the embodiment, the power supply unit 250 in the laser device 100 was specifically described, but the present invention can be applied to any inverter device, not limited to this. For example, the present invention may be applied to a battery charging system or an inverter device installed in an electric construction machine.

[0059] The configuration, operation, and function of each device and method described in the embodiments can be realized by hardware resources or software resources, or by the cooperation of hardware resources and software resources. Hardware resources include, for example, processors, ROMs, RAMs, and various integrated circuits. Software resources include, for example, operating systems and application programs. [Explanation of Symbols]

[0060] 100 Laser device, 200 Laser resonator, 250 Power supply unit, 400 High-frequency power supply, 410 DC-RF converter, 412 Inverter, 420 High-frequency signal generation unit, 460 Phase shift amount determination unit.

Claims

1. A power supply device for driving a laser resonator including a pair of discharge electrodes, An inverter comprising at least two switching elements connected in series between a high-potential line and a low-potential line, which converts the DC voltage between the high-potential line and the low-potential line into an AC voltage by switching control of each switching element and applies it to the pair of discharge electrodes from the connection point of each switching element, A control signal application unit capable of applying a control signal to at least one of the control terminals of the switching element, which includes an on-level where the switching element is turned on, an off-level where the switching element is turned off, and an intermediate level between the on-level and the off-level where the switching element is at least partially turned on. Equipped with, The switching element comprises a first switching element pair consisting of a first high-potential side switching element and a first low-potential side switching element connected in series between the high-potential line and the low-potential line, and a second switching element pair consisting of a second high-potential side switching element and a second low-potential side switching element connected in series between the high-potential line and the low-potential line. The control signal application unit is a power supply device that changes at least one of the following in accordance with the load of the laser resonator: a first overlapping period in which a first high-potential-side control signal applied to the control terminal of the first high-potential-side switching element and a second low-potential-side control signal applied to the control terminal of the second low-potential-side switching element are both on-level or at an intermediate level; and a second overlapping period in which a second high-potential-side control signal applied to the control terminal of the second high-potential-side switching element and a first low-potential-side control signal applied to the control terminal of the first low-potential-side switching element are both on-level or at an intermediate level.

2. The power supply device according to claim 1, wherein the control signal application unit changes the first overlap period by changing the relative phase of the first high-potential side control signal and the second low-potential side control signal, which have substantially the same waveform, and / or changes the second overlap period by changing the relative phase of the second high-potential side control signal and the first low-potential side control signal, which have substantially the same waveform.

3. The control signal application unit is If the first overlap period and / or the second overlap period is greater than or equal to a predetermined threshold, the first high-potential-side control signal and the second low-potential-side control signal and / or the second high-potential-side control signal and the first low-potential-side control signal are switched between the off-level and the on-level. If the first overlap period and / or the second overlap period is less than the threshold, the first high-potential-side control signal and the second low-potential-side control signal and / or the second high-potential-side control signal and the first low-potential-side control signal are switched between the off-level, the intermediate level, and the on-level. The power supply device according to claim 1 or 2.

4. The power supply device according to claim 1 or 2, wherein the control signal when taking the intermediate level transitions from the off level to the intermediate level, from the intermediate level to the on level, from the on level to the intermediate level, and from the intermediate level to the off level.

5. The power supply device according to claim 4, wherein the length of the intermediate level period when the control signal transitions from the off level to the on level is substantially equal to the length of the intermediate level period when the control signal transitions from the on level to the off level.

6. The intermediate level includes at least one first intermediate level on the off-level side and at least one second intermediate level on the on-level side. When each of the aforementioned intermediate levels is taken, the control signal transitions from the off level to the first intermediate level, from the first intermediate level to the second intermediate level, from the second intermediate level to the on level, from the on level to the second intermediate level, from the second intermediate level to the first intermediate level, and from the first intermediate level to the off level. The power supply device according to claim 4.

7. The multiple intermediate levels, including the first intermediate level and the second intermediate level, are provided substantially continuously. When each of the aforementioned intermediate levels is taken, the control signal transitions continuously between the off-level and the on-level via the continuous intermediate levels. The power supply device according to claim 6.

8. The power supply device according to claim 1 or 2, wherein the lengths of the first overlap period and the second overlap period are substantially equal.

9. An inverter comprising at least two switching elements connected in series between a high-potential line and a low-potential line, which converts the DC voltage between the high-potential line and the low-potential line into an AC voltage by switching control of each switching element and outputs it from the connection point of each switching element, A control signal application unit capable of applying a control signal to at least one of the control terminals of the switching element, which includes an on-level where the switching element is turned on, an off-level where the switching element is turned off, and an intermediate level between the on-level and the off-level where the switching element is at least partially turned on. Equipped with, The switching element comprises a first switching element pair consisting of a first high-potential side switching element and a first low-potential side switching element connected in series between the high-potential line and the low-potential line, and a second switching element pair consisting of a second high-potential side switching element and a second low-potential side switching element connected in series between the high-potential line and the low-potential line. The control signal application unit is an inverter device that changes at least one of the following according to the load to be driven by the inverter: a first overlapping period in which the first high-potential-side control signal applied to the control terminal of the first high-potential-side switching element and the second low-potential-side control signal applied to the control terminal of the second low-potential-side switching element are both on-level or at an intermediate level; and a second overlapping period in which the second high-potential-side control signal applied to the control terminal of the second high-potential-side switching element and the first low-potential-side control signal applied to the control terminal of the first low-potential-side switching element are both on-level or at an intermediate level.

Images