High frequency power supply device

Abstract

To provide a high frequency power supply device capable of suppressing fluctuation of output voltage of a step-up chopper circuit through feed-forward control with a simple configuration to suppress fluctuation of output power of the high frequency power supply.SOLUTION: A high frequency power supply device comprises: a step-up chopper circuit for stepping up a DC voltage converted from an AC voltage supplied from an AC power supply; a high frequency generating unit for supplying a load with a high frequency power by outputting a high frequency voltage toward the load on the basis of the stepped-up DC voltage; a power command unit for outputting a power setting value used as a target value for the high frequency power supplied by the high frequency generating unit; a fluctuation width calculation unit for calculating a difference between the power setting value output from the power command unit and the power setting value previously output from the power command unit as a power setting value fluctuation width; and a control unit for controlling the step-up chopper circuit so that the DC voltage output from the step-up chopper circuit becomes a predetermined voltage setting value. The control unit performs feed-forward control on the basis of the power setting value fluctuation width calculated by the fluctuation width calculation unit.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a high-frequency power supply device.

Background Art

[0002] In a plasma generator, for example, when anisotropically etching a sample such as a semiconductor wafer, a high-frequency power supply is used. When the power command value is changed during the operation of the high-frequency power supply, the load seen from the DC power supply unit that supplies DC voltage to the high-frequency generation unit that outputs high-frequency power appears to vary. In this case, when a boost chopper circuit is built into the DC power supply unit, switching between the discontinuous mode and the continuous mode occurs during load variation, and only feedback control of the output voltage of the boost chopper circuit causes the output voltage to vary, and the output power also varies as a high-frequency power supply.

[0003] As a technique for suppressing the distortion of the output voltage of such a boost chopper circuit, a technique for suppressing the output distortion of the boost chopper circuit by using the control ratio of an inverter in the subsequent stage of the boost chopper circuit is disclosed (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the prior art, since a value calculated by feedback control on the inverter side or the like is used as the control ratio of the inverter, there is a problem that the control system becomes complicated and the amount of calculation increases.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a high-frequency power supply device capable of suppressing fluctuations in the output voltage of a boost chopper circuit and suppressing fluctuations in the output power of a high-frequency power supply by feed-forward control with a simple configuration.

Means for Solving the Problems

[0007] In order to solve the above-described problems and achieve the object, a high-frequency power supply device according to the present invention includes a boost chopper circuit that boosts a DC voltage converted from an AC voltage supplied from an AC power supply, and a high-frequency voltage based on the DC voltage boosted by the boost chopper circuit. A high-frequency generation unit that supplies high-frequency power to the load by outputting the load toward the load, a power command unit that outputs a power setting value that is a target value of the high-frequency power supplied by the high-frequency generation unit, and the power setting value output from the power command unit And a variation width calculation unit that calculates a difference between the power setting value output from the power command unit last time as a power setting value variation width, and a control unit that controls the boost chopper circuit so that the DC voltage output from the boost chopper circuit becomes a predetermined voltage setting value. The control unit performs feed-forward control based on the power setting value variation width calculated by the variation width calculation unit.

Effects of the Invention

[0008] According to the present invention, fluctuations in the output voltage of the boost chopper circuit can be suppressed by feed-forward control with a simple configuration, and fluctuations in the output power of the high-frequency power supply can be suppressed.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

[0010] Hereinafter, embodiments of the high-frequency power supply according to the present invention will be described in detail with reference to FIGS. 1 to 5. Further, the present invention is not limited by the following embodiments, and the constituent elements in the following embodiments include those that can be easily conceived by those skilled in the art, substantially the same ones, and those within the so-called equivalent range. Furthermore, various omissions, substitutions, changes, and combinations of the constituent elements can be made without departing from the gist of the following embodiments.

[0011] (Overview of the overall configuration of the high-frequency power supply) FIG. 1 is a diagram for explaining the overview of the overall configuration of the high-frequency power supply according to the embodiment. With reference to FIG. 1, the overview of the overall configuration of the high-frequency power supply 1 according to the present embodiment will be described.

[0012] As shown in FIG. 1, the high-frequency power supply 1 includes an AC-DC conversion unit 10 and a high-frequency generation unit 11.

[0013] The AC-DC conversion unit 10 is a circuit that converts the AC voltage supplied from the AC power supply 2 into a DC voltage. In the present embodiment, in order to suppress fluctuations in the output power of the high-frequency generation unit 11 described below, fluctuations in the output voltage of the AC-DC conversion unit 10 are suppressed, specifically, fluctuations in the output voltage of a boost chopper circuit 200 described later included in the AC-DC conversion unit 10 are suppressed. Details of the operation for suppressing fluctuations in the output voltage of the boost chopper circuit 200 will be described later.

[0014] The high-frequency generation unit 11 is a circuit that converts the DC voltage converted by the AC-DC conversion unit 10 into a high-frequency AC voltage, that is, a high-frequency voltage, and outputs it toward the load 3. By outputting a high-frequency voltage from the high-frequency generation unit 11, high-frequency power is supplied to the load 3. Here, the high frequency indicates the frequency in the RF (Radio Frequency) band. The frequencies in the RF band are industrial frequencies such as 13.56 MHz, 27.12 MHz, 40.68 MHz, etc.

[0015] (Details of the circuit configuration of the high-frequency power supply) FIG. 2 is a diagram showing an example of the circuit configuration of the high-frequency power supply according to the embodiment. The details of the circuit configuration of the high-frequency power supply 1 according to the present embodiment will be described with reference to FIG. 2.

[0016] As shown in FIG. 2, in addition to the AC-DC conversion unit 10 and the high-frequency generation unit 11 shown in FIG. 1 above, the high-frequency power supply 1 includes a voltage detection unit 21, an AD conversion unit 22, a voltage control controller 23, a voltage detection unit 31, an AD conversion unit 32, a voltage control controller 33, a power detection unit 41, an AD conversion unit 42, a power control controller 43, a power command unit 44, a power set value fluctuation width calculation unit 45, and a low-pass filter unit 46.

[0017] As shown in FIG. 2, the AC-DC conversion unit 10 includes a rectifying and smoothing circuit 100, a boost chopper circuit 200, and a buck chopper circuit 300.

[0018] The rectifying and smoothing circuit 100 is a circuit that converts the AC voltage supplied from the AC power supply 2 into a DC voltage by rectifying the AC voltage by full-wave rectification or the like and smoothing the rectified current. For example, a diode bridge or the like is used to full-wave rectify the AC voltage.

[0019] The boost chopper circuit 200 is a circuit that boosts the DC voltage converted by the rectifier smoothing circuit 100. As shown in Fig. 2, the boost chopper circuit 200 includes inductors 201a to 201c, diodes 202a to 202c, switching elements 203a to 203c, and freewheeling diodes 204a to 204c.

[0020] The inductors 201a to 201c are coil members that accumulate or release energy according to the switching operations of the respective switching elements 203a to 203c. For example, when the switching element 203a is on, the inductor 201a accumulates energy due to the current flowing in the order of the rectifier smoothing circuit 100, the inductor 201a, the switching element 203a, and the rectifier smoothing circuit 100. When the switching element 203a is off, the inductor 201a releases energy as a current flowing in the order of the rectifier smoothing circuit 100, the inductor 201a, the diode 202a, the smoothing capacitor 205, the buck chopper circuit 300, and the rectifier smoothing circuit 100. The same applies to the inductors 201b and 201c.

[0021] The diodes 202a to 202c are rectifying elements that prevent the current due to the discharge of the charge accumulated in the smoothing capacitor 205 from flowing backward.

[0022] The switching elements 203a to 203c are elements that perform on-off switching operations in order to repeatedly accumulate and release energy in the respective inductors 201a to 201c. The switching elements 203a to 203c are, for example, MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) or IGBTs (Insulated Gate Bipolar Transistors).

[0023] The freewheeling diodes 204a to 204c are diodes for returning energy to protect the freewheeling diodes 204a to 204c from the high voltage generated when the current is cut off by the respective switching elements 203a to 203c.

[0024] The smoothing capacitor 205 is a capacitor for smoothing the DC voltage boosted by the action of the inductors 201a to 201c, the diodes 202a to 202c, and the switching elements 203a to 203c. Further, the smoothing capacitor 205 has a larger capacitance than the smoothing capacitor 304 of the step-down chopper circuit 300 described later, and the DC voltage boosted by the step-up chopper circuit 200 is output for the purpose of stable voltage supply. That is, since the DC voltage output by the step-up chopper circuit 200 is required to be stably supplied, in this embodiment, this is achieved by the feed-forward control described later.

[0025] Note that the step-up chopper circuit 200 shown in FIG. 2 is a three-phase step-up chopper circuit, but it is not limited thereto, and for example, it may be a single-phase step-up chopper circuit.

[0026] The step-down chopper circuit 300 is a circuit for stepping down the DC voltage output by the step-up chopper circuit 200. As shown in FIG. 2, the step-down chopper circuit 300 includes switching elements 301a to 301f, freewheeling diodes 302a to 302f, inductors 303a to 303c, and a smoothing capacitor 304.

[0027] The switching elements 301a to 301f are elements that perform an on-off switching operation in order to repeatedly accumulate and release energy in each of the inductors 303a to 303c. The switching elements 301a to 301f are, for example, MOSFETs or IGBTs.

[0028] The freewheeling diodes 302a to 302f are diodes for returning energy in order to protect the freewheeling diodes 302a to 302f from the high voltage generated when the current is cut off by each of the switching elements 301a to 301f.

[0029] Inductors 303a to 303c are coil members that accumulate or release energy according to the switching operations of the switching elements 301a to 301f respectively. For example, when switching element 301a is on and switching element 301b is off, inductor 303a accumulates energy by the current flowing in the order of boost chopper circuit 200, switching element 301a, inductor 303a, smoothing capacitor 304, high-frequency generation unit 11, and then boost chopper circuit 200. Also, when switching element 301a is off and switching element 301b is on, inductor 303a releases energy as the current flowing in the order of inductor 303a, smoothing capacitor 304, high-frequency generation unit 11, switching element 301b, and then inductor 303a. The same applies to inductors 303b and 303c.

[0030] Smoothing capacitor 304 is a capacitor for smoothing the DC voltage stepped down by the actions of the switching elements 301a to 301f and inductors 303a to 303c. Also, the capacitance of smoothing capacitor 304 is smaller than that of smoothing capacitor 205 of the boost chopper circuit 200 described above, and the DC voltage stepped down by the buck chopper circuit 300 is output to the high-frequency generation unit 11 for the purpose of fast voltage response.

[0031] Voltage detection unit 21 is a circuit that detects the voltage value of the DC voltage output by the boost chopper circuit 200. AD conversion unit 22 is a circuit that converts the voltage value of the output voltage of the boost chopper circuit 200 detected by the voltage detection unit 21 from an analog value to a digital value.

[0032] The voltage control controller 23 is a controller that performs feedback control so that the DC voltage output from the boost chopper circuit 200 becomes a desired voltage set value (for example, a fixed value) based on the voltage value of the output voltage of the boost chopper circuit 200 converted by the AD conversion unit 22. Specifically, the voltage control controller 23 controls the boost operation by turning on and off the switching elements 203a to 203c of the boost chopper circuit 200 so as to obtain a desired voltage set value. Note that the "control unit" of the present invention corresponds to the voltage control controller 23.

[0033] Also, as shown in FIG. 2, in the present embodiment, the voltage control controller 23 inputs a feed-forward addition value based on the power set value for the high-frequency power output from the high-frequency generation unit 11, and performs feed-forward control using the feed-forward addition value. Specifically, the voltage control controller 23 adds the feed-forward addition value to the control amount calculated from the difference between the desired voltage set value stored in a storage means (not shown) and the output voltage of the boost chopper circuit 200 from the feedback AD conversion unit 22, and based on the added control amount, performs on / off control of the switching elements 203a to 203c. Note that the feed-forward control by the voltage control controller 23 will be described in detail in FIGS. 3 and 4.

[0034] The voltage detection unit 31 is a circuit that detects the voltage value of the DC voltage output by the buck chopper circuit 300. The AD conversion unit 32 is a circuit that converts the voltage value of the output voltage of the buck chopper circuit 300 detected by the voltage detection unit 31 from an analog value to a digital value.

[0035] The voltage control controller 33 is a controller that performs feedback control so that the DC voltage output from the step-down chopper circuit 300 becomes a desired voltage set value stored in storage means (not shown) based on the voltage value of the output voltage of the step-down chopper circuit 300 converted by the AD conversion unit 32. Specifically, the voltage control controller 33 controls the step-down operation by turning on and off the switching elements 301a to 301f of the step-down chopper circuit 300 so as to obtain a desired voltage set value.

[0036] The power detection unit 41 is a circuit that detects the high-frequency power converted by the high-frequency generation unit 11, that is, the power value of the high-frequency power output as the high-frequency power source 1. The AD conversion unit 42 is a circuit that converts the power value of the high-frequency power of the high-frequency generation unit 11 detected by the power detection unit 41 from an analog value to a digital value.

[0037] The power control controller 43 is a controller that performs feedback control so that the high-frequency power output from the high-frequency generation unit 11 becomes a power set value that is a target value commanded by the power command unit 44 based on the power value of the high-frequency power of the high-frequency generation unit 11 converted by the AD conversion unit 42.

[0038] The power command unit 44 is a circuit that commands the power control controller 43 with a power set value set by an external operation or command information from an external device. Further, the power command unit 44 outputs the set power set value to the power set value variation width calculation unit 45.

[0039] The power set value variation width calculation unit 45 is a circuit that calculates the difference between the power set value commanded by the power command unit 44 and the power set value commanded by the power command unit 44 last time as the power set value variation width. Further, the power set value variation width calculation unit 45 outputs a value obtained by multiplying the calculated power set value variation width by a predetermined gain to the low-pass filter unit 46. Note that the "variation width calculation unit" of the present invention corresponds to the power set value variation width calculation unit 45.

[0040] The low-pass filter section 46 is a circuit that applies, for example, an IIR (Infinite Impulse Response) filter as a low-pass filter to the value obtained by multiplying the power setting value fluctuation range output from the power setting value fluctuation range calculation section 45 by a gain. Then, the low-pass filter section 46 outputs, as a feed-forward addition value, the value obtained by applying the low-pass filter to the value obtained by multiplying the power setting value fluctuation range by the gain to the voltage control controller 23. That is, the feed-forward addition value is calculated by the following formula (1).

[0041] Feed-forward addition value = Power setting value fluctuation range × Gain × Low-pass filter …(1)

[0042] In this way, by applying the low-pass filter to the power setting value fluctuation range (value multiplied by the gain) by the low-pass filter section 46, it is possible to suppress inrush current and the like generated by a sharp change in the power setting value fluctuation range and output the feed-forward addition value to the voltage control controller 23.

[0043] (Control operation of boost chopper circuit) FIG. 3 is a diagram showing an example of the control flow of the boost chopper circuit of the high-frequency power supply according to the embodiment. FIG. 4 is a diagram for explaining the feed-forward addition value for the boost chopper circuit of the high-frequency power supply according to the embodiment. The control operation of the boost chopper circuit 200 of the high-frequency power supply 1 according to the present embodiment will be described with reference to FIGS. 3 and 4.

[0044] In the boosting operation of the boost chopper circuit 200, depending on the current flowing on the load side as viewed from the boost chopper circuit 200, during the boosting operation, there are always a continuous mode in which current flows through the inductors 201a to 201c and a discontinuous mode in which current flows intermittently through the inductors 201a to 201c. Therefore, during the operation of the high-frequency power supply 1, switching between the discontinuous mode and the continuous mode may occur in the boost chopper circuit 200 depending on the magnitude of the load 3.

[0045] When the boost chopper circuit 200 operates in continuous mode, assuming the input voltage applied to the boost chopper circuit 200 is Vin, the output voltage output from the boost chopper circuit 200 is Vout, and the duty ratio of the on / off operation of the switching elements 203a to 203c is Duty, the output voltage Vout is calculated by the following formula (2).

[0046] Vout = 1 / (1 - Duty) × Vin …(2)

[0047] However, when the boost chopper circuit 200 operates in discontinuous mode, the above formula (2) does not hold. Therefore, since the switching between discontinuous mode and continuous mode occurs during the operation of the high-frequency power supply 1 as described above, the duty ratio Duty required to keep the output voltage of the boost chopper circuit 200 constant changes significantly. Therefore, in the control of the boost chopper circuit 200 by the voltage control controller 23, if simple feedback control using the output voltage detected by the voltage detection unit 21 is performed, it cannot immediately respond to the switching between discontinuous mode and continuous mode, and fluctuations such as distortion occur in the output voltage of the boost chopper circuit 200. Therefore, in the present embodiment, in order to cope with the switching between discontinuous mode and continuous mode, which causes fluctuations in the output voltage of the boost chopper circuit 200, a feedforward addition value is added to the control amount of the voltage control controller 23, and the on / off control of the switching elements 203a to 203c is performed to suppress fluctuations in the output voltage of the boost chopper circuit 200.

[0048] The control using the feed-forward addition value by the boost chopper circuit 200 is specifically performed as follows. As shown in FIG. 3, the voltage control controller 23 calculates a control amount from the difference between a desired voltage set value and the output voltage of the boost chopper circuit 200 detected by the voltage detection unit 21 and converted into a digital value by the AD conversion unit 22, and performs feedback control based on the control amount. Further, in order to cancel in advance the predicted output voltage fluctuation, the voltage control controller 23 adds the feed-forward addition value based on the power set value fluctuation width calculated by the above formula (1) to the above control amount, and then performs feed-forward control for performing the on / off operation of the switching elements 203a to 203c. The voltage control controller 23 performs the feed-forward control when the boost chopper circuit 200 is operating in the discontinuous mode.

[0049] Next, the feed-forward control when the boost chopper circuit 200 switches from the discontinuous mode to the continuous mode due to the fluctuation of the power set value output from the power command unit 44 will be described with reference to FIG. 4. For example, assume that the power set value output from the power command unit 44 last time was 0 [W], and a power set value of 1500 [W] is newly output from the power command unit 44. That is, assume that the output power of the high-frequency generation unit 11 is changed from 0 [W] to 1500 [W]. Here, it is assumed that when the high-frequency generation unit 11 outputs power of 1000 [W], the boost chopper circuit 200 switches from the discontinuous mode to the continuous mode.

[0050] In this case, the power setting value variation width calculation unit 45 calculates a power setting value variation width of 1500 [W] as the difference between the power setting value of 1500 [W] commanded by the power command unit 44 and the power setting value of 0 [W] commanded by the power command unit 44 last time. However, here, when the output power of the high-frequency generation unit 11 changes from 0 [W] to 1500 [W], since the output power (high-frequency power) of the high-frequency generation unit 11 switches from the discontinuous mode to the continuous mode when it is 1000 [W], the section of 0 [W] to 1000 [W], which is the part of the discontinuous mode in the variation width from 0 [W] to 1500 [W], is taken as the power setting value variation width. That is, as described above, when the high-frequency generation unit 11 outputs a power of 1000 [W], since the boost chopper circuit 200 switches from the discontinuous mode to the continuous mode, taking this 1000 [W] as the upper limit value (applied setting power upper limit value), the power setting value variation width calculation unit 45 calculates the part of the calculated power setting value variation width of 1500 [W] that is below the upper limit value as the new power setting value variation width (here 1000 [W]). Then, the power setting value variation width calculation unit 45 outputs a value obtained by multiplying the calculated power setting value variation width of 1000 [W] by a predetermined gain to the low-pass filter unit 46. Then, the low-pass filter unit 46 outputs a value obtained by applying a low-pass filter to the value obtained by multiplying the power setting value variation width of 1000 [W] by the gain as a feed-forward addition value to the voltage control controller 23.

[0051] That is, in the above example, as shown in FIG. 4, when the power setting value variation width calculated as the difference between the power setting value commanded from the power command unit 44 and the power setting value commanded from the power command unit 44 last time is equal to or less than the applicable setting power upper limit value (here, when the power setting value commanded from the power command unit 44 is equal to or less than the applicable setting power upper limit value), the value obtained by applying a low-pass filter to the value obtained by multiplying the power setting value variation width by a gain (the slope of the graph) is calculated as the feed-forward addition value. On the other hand, when the power setting value variation width exceeds the applicable setting power upper limit value (here, when the power setting value commanded from the power command unit 44 exceeds the applicable setting power upper limit value), the value obtained by applying a low-pass filter to the value obtained by multiplying the portion of the power setting value variation width that is equal to or less than the applicable setting power upper limit value by a gain (the slope of the graph) is calculated as the feed-forward addition value. That is, only the portion of the power setting value variation width calculated by the power setting value variation width calculation unit 45 that operates in the discontinuous mode, that is, the portion that is equal to or less than the applicable setting power upper limit value, contributes to the feed-forward control. In the above example, when the power setting value variation width exceeds 1000 [W], the power setting value commanded from the power command unit 44 exceeds the applicable setting power upper limit value of 1000 [W]. Therefore, as shown in FIG. 4, the same feed-forward addition value as when the power setting value variation width is calculated to be 1000 [W] is calculated.

[0052] (Example of Suppressing Variation of Output Voltage by Feed-Forward Control of Boost Chopper Circuit) FIG. 5 is a diagram for explaining a state in which the variation of the output power of the high-frequency power supply according to the embodiment is suppressed. While referring to FIG. 5, an example in which the variation of the output voltage by the feed-forward control of the boost chopper circuit 200 of the high-frequency power supply 1 according to the present embodiment is suppressed will be described.

[0053] First, assume a case where the power command unit 44 repeatedly changes and outputs 0 [W] and a predetermined value (for example, 1500 [W]) as power set values (that is, outputs in a pulsed manner). And assume that the voltage control controller 23 only performs feedback control to calculate a control amount from the difference between a desired voltage set value and the output voltage of the boost chopper circuit 200 detected by the voltage detection unit 21 and converted into a digital value by the AD conversion unit 22. The waveforms of the output power of the high-frequency generation unit 11 in this case are shown in FIGS. 5(a) and 5(b). In response to the power command unit 44 repeatedly changing and outputting 0 [W] and the predetermined value as power set values, the high-frequency generation unit 11 outputs a voltage with a waveform as shown in FIG. 5(a). In this case, as shown in FIG. 5(b), it is grasped that an overshoot occurs in the output voltage output from the high-frequency generation unit 11 at the timing when the power set value output from the power command unit 44 is switched from 0 [W] to the predetermined value. This is because, as described above, in the simple feedback control by the voltage control controller 23, it cannot immediately respond to the switching from the discontinuous mode to the continuous mode, and fluctuations such as distortion occur in the output voltage of the boost chopper circuit 200.

[0054] On the other hand, in addition to the above-described feedback control, the voltage controller 23 adds a feedforward addition value based on the power setting value variation width calculated by the power setting value variation width calculation unit 45 to the control amount in order to cancel out in advance the predicted variation in the output voltage, and then performs feedforward control for performing the on / off operation of the switching elements 203a to 203c. Assume a case where feedforward control is performed. The waveforms of the output voltage of the high-frequency generation unit 11 in this case are shown in FIGS. 5(c) and 5(d). As the power command unit 44 repeatedly changes and outputs 0 [W] and a predetermined value as the power setting value, the high-frequency generation unit 11 outputs a voltage having a waveform as shown in FIG. 5(c). In this case, as shown in FIG. 5(d), at the timing when the power setting value output from the power command unit 44 switches from 0 [W] to the predetermined value, due to the feedforward control for the boost chopper circuit 200 described above, the predicted variation in the output voltage of the high-frequency generation unit 11 is canceled out. As a result, it is understood that the overshoot in the output voltage output from the high-frequency generation unit 11 is reduced.

[0055] As described above, in the high-frequency power supply 1 according to the present embodiment, the boost chopper circuit 200 boosts the DC voltage converted from the AC voltage supplied from the AC power supply 2, and the high-frequency generation unit 11 outputs high-frequency power based on the DC voltage boosted by the boost chopper circuit 200. The power command unit 44 outputs a power setting value that is the target value of the high-frequency power output by the high-frequency generation unit 11. The power setting value fluctuation width calculation unit 45 calculates the difference between the power setting value output from the power command unit 44 and the power setting value output from the power command unit 44 last time as the power setting value fluctuation width. The voltage control controller 23 controls the boost chopper circuit 200 so that the DC voltage output from the boost chopper circuit 200 becomes a predetermined voltage setting value, and performs feed-forward control based on the power setting value fluctuation width calculated by the power setting value fluctuation width calculation unit 45. Specifically, the power setting value fluctuation width calculation unit 45 outputs a value obtained by multiplying the power setting value fluctuation width by a predetermined gain. The voltage control controller 23 controls the boost chopper circuit 200 by adding the value calculated by the power setting value fluctuation width calculation unit 45 to the control amount calculated to control the DC voltage output from the boost chopper circuit 200 to be the voltage setting value as feed-forward control. As a result, the fluctuation of the output voltage of the boost chopper circuit 200 can be suppressed by the feed-forward control with a simple configuration, and the fluctuation of the output power of the high-frequency power supply 1 can be suppressed.

Explanation of Signs

[0056] 1 High-frequency power supply 2 AC power supply 3 Load 10 AC-DC conversion unit 11 High-frequency generation unit 21 Voltage detection unit 22 AD conversion unit 23 Voltage control controller 31 Voltage detection unit 32 AD conversion unit 33 Voltage control controller 41 Power detection unit 42 AD conversion unit 43 Power control controller 44 Power Command Unit 45 Power Setpoint Variation Calculation Unit 46 Low-Pass Filter Unit 100 Rectifier and Smoothing Circuit 200 Boost Chopper Circuit 201a~201c Inductor 202a~202c Diode 203a~203c Switching Element 204a~204c Freewheeling Diode 205 Smoothing Capacitor 300 Buck Chopper Circuit 301a~301f Switching Element 302a~302f Freewheeling Diode 303a~303c Inductor 304 Smoothing Capacitor

Claims

1. A boost chopper circuit that boosts a DC voltage converted from an AC voltage supplied from an AC power source; A high-frequency generation unit that supplies high-frequency power to the load by outputting a high-frequency voltage toward the load based on the DC voltage boosted by the boost chopper circuit; A power command unit that outputs a power setting value that is a target value of the high-frequency power supplied by the high-frequency generation unit; A variation width calculation unit that calculates, as a power setting value variation width, the difference between the power setting value output from the power command unit and the power setting value output from the power command unit last time; A control unit that controls the boost chopper circuit so that the DC voltage output from the boost chopper circuit becomes a predetermined voltage setting value; Comprising; The control unit is a high-frequency power supply device that performs feed-forward control based on the power setting value variation width calculated by the variation width calculation unit.

2. The variation width calculation unit outputs a value obtained by multiplying the power setting value variation width by a predetermined gain, The control unit controls the boost chopper circuit by adding the value calculated by the variation width calculation unit to the control amount calculated to control the DC voltage output from the boost chopper circuit to become the voltage setting value as the feed-forward control. The high-frequency power supply device according to claim 1.

3. Further comprising a low-pass filter unit that applies a low-pass filter to the value calculated by the variation width calculation unit, The control unit controls the boost chopper circuit by adding the value to which the low-pass filter is applied by the low-pass filter unit to the control amount as the feed-forward control. The high-frequency power supply device according to claim 2.

4. The control unit performs the feed-forward control only when the boost chopper circuit is operating in discontinuous mode. The high-frequency power supply device according to any one of claims 1 to 3.

5. When the boost chopper circuit switches from discontinuous mode to continuous mode according to the power setting value output from the power command unit, the control unit, among the power setting value variation widths calculated by the variation width calculation unit, based on the portion corresponding to the high-frequency power or less when switching from discontinuous mode to continuous mode, performs the feed-forward control. The high-frequency power supply device according to claim 4.

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