JP2007169730A - Ac power supply device, and arc preventive method in the device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an AC power supply device capable of preventing generation of any arc discharge and rapidly and continuously performing the shut-off control of the high frequency AC power to be supplied to a load device, and an arc preventive method in the device. <P>SOLUTION: A current level setting instrument 33 sets the current level command value based on the value operated from the DC power command value and the discharge voltage value, and the winding ratio of a high frequency transformer 10. A command selector 34 sets the current level command value of the stationary mode or the current level command value of the starting or re-starting mode. A first comparator 43 compares the current level value with the current level command value, and when the current level value is equal to or exceeds the current level command value, the control shut-off signal is output in a shut-off signal generator 44. A gate control breaker 54 turns OFF the pulse of the switching control signal G. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an AC power supply device, and more particularly to a technique for preventing the generation of an arc generated in the course of a process in the field of a manufacturing apparatus for manufacturing a semiconductor, a liquid crystal substrate, or the like using a process such as sputtering. is there.

  Generally, in a sputtering apparatus, a sputtering process is realized by generating a plasma discharge in a manufacturing apparatus. In order to realize this process, it is necessary to use a high-voltage direct current (DC) power supply or alternating current (AC) power supply, and this power supply must be applied to the electrodes in the manufacturing equipment, which generates plasma discharge. To do.

  However, when this high-voltage power supply is applied between the electrodes where the plasma is floating, breakdown voltage occurs between the electrodes, a short circuit phenomenon occurs, and an excessive current may flow. This short-circuit phenomenon is a so-called arc phenomenon. When this arc is generated, there is a problem that foreign matter is scattered in the product and the commercial value is impaired. For this reason, it is indispensable to suppress the influence on the product by capturing the arc phenomenon and cutting off the power supply at high speed. Conventionally, in many cases, a DC power source has been used as a power source applied between the electrodes, but an AC power source is also used. As a method of capturing this arc phenomenon, a change in supplied DC current or AC current is captured. The method is used. In this system, when an apparatus that supplies power supplies an arc phenomenon, the power supply to the manufacturing apparatus is interrupted at a high speed, and the manufacturing apparatus is restarted after a certain time has elapsed.

  As an apparatus for capturing such an arc phenomenon and interrupting at high speed, there is one disclosed in Patent Document 1. FIG. 9 is a diagram illustrating a configuration of a conventional power supply device. When the arc phenomenon in the processing apparatus main body 76 is caught, the power supply apparatus cuts off the electric power supplied to the processing apparatus main body 76 at a high speed, and when the processing apparatus main body 76 is subsequently restarted, the inverter switching unit 73. The switching pulse width to the power element is increased temporarily. In this power supply device, a direct current voltage converted from commercial power by the direct current control unit 71 and taken out via the smoothing circuit 72 is sent to the inverter switching unit 73 and converted into alternating current (rectangular wave). It is supplied to the processing apparatus main body 76 via the rectifying unit 75. The current detection circuit 80 reads the current detected by the current transformer 79 provided between the step-up transformer 74 and the rectifier 75 and sends a control signal corresponding to the value to the thyristor controller 77 and the inverter controller 78. The thyristor control unit 77 receives a control signal corresponding to the current value, generates and outputs a gate control signal for controlling the DC control unit 71. In addition, the inverter control unit 78 inputs a control signal corresponding to the current value and a temperature value from a temperature detector 81 provided at a predetermined location of the processing apparatus main body 76 to control the inverter switching unit 73. The switching control signal is generated and output.

  FIG. 10 is a diagram showing signal waveforms at various parts in the power supply device shown in FIG. 9, and shows waveforms before and after the occurrence of arc discharge. FIG. 10A shows the signal waveform of the discharge current, that is, the waveform of the current detection output of the current transformer 79. The discharge current in period (1) shows a regular pulse current waveform, and the discharge is controlled by adjusting the duty. FIG. 10B shows the DC voltage Vdc obtained from the smoothing circuit 72. In the period (1), the DC voltage Vdc is kept constant at 200V. In the period (2), the glow discharge is changed to the arc discharge, and the current increases rapidly. FIG. 10C shows an arc detection signal P when arc discharge occurs. When the inverter control unit 78 restarts the oscillation of the inverter switching unit 73 at the same frequency in the return period (4) after the interruption period (3) ends, the duty of the high frequency pulse is as shown in FIG. , Gradually increase from zero to the duty before arc detection. As shown in FIG. 10 (b), the discharge current value gradually increases in the same manner as the duty according to the change of the DC voltage Vdc, and returns to the state before the arc detection at the end of the return period (4).

Japanese Patent Laid-Open No. 7-62521

  When the power supply device disclosed in Patent Document 1 detects an arc discharge, the power supply to the processing device main body 76 is cut off, and when the variable power is supplied again after a predetermined time has elapsed, the duty of the variable power high frequency pulse is set. Increase gradually from zero. However, when such a restart process is performed, arc discharge recurs in a situation where the electrode of the load that is the processing apparatus main body 76 is heated, and a thermal change occurs in the electrode, and the process is not constant. There is a fear. In this case, the quality of the product is lowered or the product yield is deteriorated.

  Further, as described above, the interruption process after detecting the arc discharge has a problem that the arc energy cannot be sufficiently suppressed due to the operation delay of the circuit, the waste time, and the like. Essentially, in order to sufficiently suppress arc energy, it is necessary to prevent arc discharge from occurring. That is, it is desirable to appropriately control the power supplied to the load device so that arc discharge does not occur.

  Accordingly, in order to solve the above-described problems, the present invention provides an AC power supply apparatus capable of preventing the occurrence of arc discharge and simultaneously realizing high-frequency AC power cut-off control supplied to a load apparatus at high speed and the apparatus. An object of the present invention is to provide a method for preventing arcing.

  In order to achieve the above object, an AC power supply according to the present invention is a power supply that converts commercial AC power into high-frequency AC power and supplies the AC power to a load device, and prevents AC discharge from occurring. In the power supply apparatus, a DC-DC power converter that converts the DC power rectified from the commercial AC power into new DC power by controlling the gate of the switching element by a gate control signal, and the converted DC power A high-frequency power converter that converts the high-frequency AC power by controlling the gate of the switching element by a switching control signal, a current detector that detects an AC current value of the AC power supplied to the load device, and Oscillation control means for outputting a switching control signal having a pulse for controlling the gate of the switching element of the high frequency power converter to the high frequency power converter The oscillation control means generates a cutoff signal based on a current level command value smaller than an arc reference current value for detecting arc discharge and the detected AC current value, and The pulse of the switching control signal is turned off by the signal, and the supply of AC power to the load device is stopped.

  Further, the oscillation control means is based on a predetermined current level command value smaller than an arc reference value for detecting arc discharge and the AC current value in a steady mode in which operation is performed without causing arc discharge. Generates a cut-off signal, in the start mode for starting AC power supply to the load device or in the restart mode after the occurrence of arc discharge, a value smaller than the arc reference current value for detecting arc discharge, A cutoff signal is generated based on a current level command value smaller than the current level command value in the steady mode and the alternating current value.

  The AC power supply apparatus according to the present invention further generates a gate control signal based on a voltage detector that detects an AC voltage value of AC power supplied to the load device, and a DC power command value that matches the load device. And power control means for outputting the gate signal to the DC-DC converter, wherein the power control means calculates an AC power value from the AC voltage value and the AC current value, and the AC power value is the DC current value. The DC power command value is decreased when it is smaller than the power command value.

  Although the present invention has been described as an AC power supply apparatus, the present invention can also be realized as a method substantially corresponding to these, and the present invention includes an arc prevention method in the AC power supply apparatus. That is, the arc prevention method in the AC power supply apparatus according to the invention is the arc prevention method in the AC power supply apparatus that converts commercial AC power to high-frequency AC power and supplies the AC power to the load device. An AC-DC rectification process for rectifying the DC power, a DC-DC power conversion process for converting the rectified DC power into new DC power by controlling the gate of the switching element by a gate control signal, and the converted DC power A high-frequency power conversion step of controlling the gate of the switching element by a switching control signal to convert it to high-frequency AC power, a current detection step of detecting an AC current value of the AC power supplied to the load device, Switching control signal having a pulse for controlling the gate of a switching element in a high-frequency power conversion process When generating, a cutoff signal is generated based on a current level command value smaller than an arc reference current value for detecting arc discharge and the detected AC current value, and the switching control signal is generated by the cutoff signal. And an oscillation control step of stopping the supply of AC power to the load device.

  The arc prevention method for an AC power supply according to the present invention includes a voltage detection step for detecting an AC voltage value of AC power supplied to the load device, and a gate control signal based on a DC power command value suitable for the load device. A power control step of calculating an AC power value from the AC voltage value and the AC current value and reducing the DC power command value when the AC power value is smaller than the DC power command value. It is characterized by having.

  As described above, according to the present invention, the power supply to the load device is interrupted by the current level command value that is smaller than the arc reference current value for detecting arc discharge. Conventionally, power supply was cut off when arc discharge occurred. However, according to the present invention, power supply can be cut off before arc discharge occurs, so it is possible to prevent the occurrence of arc discharge. It becomes. Further, when the power supply is cut off before the arc discharge occurs, a cut-off signal is generated based on the current level command value and the alternating current value, and the pulse is turned off for each pulse of the switching control signal. did. Conventionally, power supply was temporarily interrupted for a predetermined time when an arc occurred, but according to the present invention, power supply interruption control can be instantaneously performed before arc discharge occurs, It is possible to realize high-speed and continuous interruption without temporarily stopping. Furthermore, according to the present invention, when the AC power value is smaller than the DC power command value, the DC power command value is decreased. Thereby, the direct-current power converted by the DC-DC converter decreases. Therefore, it is possible to suppress the saturation of the DC voltage caused by the error between the AC power value and the DC power command value, and to obtain stable characteristics.

The best mode for carrying out the present invention will be described below with reference to the drawings.
〔Constitution〕
First, the configuration of an AC power supply apparatus according to an embodiment of the present invention will be described. FIG. 1 is a control block diagram showing the configuration of the AC power supply apparatus. The AC power supply apparatus 1 includes an AC-DC rectifier 3, a first smoothing capacitor 4, a DC-DC power converter 5, a second smoothing capacitor 6, a first voltage detector 7, and a first current detector. 8, a high-frequency power converter 9, a high-frequency transformer 10, a second voltage detector 11, a second current detector 12, a reactor 13, a DC control power supply 14, a power control means 15 and an oscillation control means 16. The AC power supply device 1 receives commercial AC power from the commercial AC power source 2, temporarily converts it to DC power, further converts DC power into AC power, and outputs the AC power to the load device 17.

  The AC-DC rectifier 3 is a three-phase full-wave rectifier circuit using a rectifying element, for example, a diode. The AC-DC rectifier 3 receives the three-phase AC power from the commercial AC power supply 2 and rectifies the three-phase AC power to generate the first DC power. To the smoothing capacitor 4. The AC-DC rectifier 3 has an output positive terminal connected to one end of the first smoothing capacitor 4 and an output negative terminal connected to the other end of the first smoothing capacitor 4. The first smoothing capacitor 4 receives DC power from the AC-DC rectifier 3, smoothes the DC voltage, and outputs the obtained first DC power to the DC-DC power converter 5. The first smoothing capacitor 4 has one end connected to the input positive terminal of the DC-DC power converter 5 and the other end connected to the input negative terminal of the DC-DC power converter 5.

  The DC-DC power converter 5 is a switching circuit including a semiconductor switching element, for example, an IGBT (Insulated Gate Bipolar Transistor) (hereinafter referred to as a first switching element) and a DC reactor, and the gate of the first switching element. Is controlled by a control signal (hereinafter referred to as a gate control signal) A input to the collector. The collector and emitter of the first switching element are connected to the negative terminals of the first smoothing capacitor 4 and the second smoothing capacitor 6, respectively. The DC reactor has one end connected to the positive terminal of the first smoothing capacitor 4 and the other end connected to the positive terminal of the second smoothing capacitor 6. That is, the DC-DC power converter 5 receives the first DC power, turns on / off the gate of the first switching element that is present by the gate control signal A, and converts the second DC power to the second DC power. Output to the smoothing capacitor 6.

  The second smoothing capacitor 6 receives the second DC power, smoothes the second DC voltage, and outputs it to the high-frequency power converter 9. One end of the second smoothing capacitor 6 is connected to the input positive terminal of the high-frequency power converter 9 and the input positive terminal of the first voltage detector 7, and the other end is connected to the input negative terminal of the high-frequency power converter 9 and It is connected to the input negative terminal of the first voltage detector 7. The first voltage detector 7 detects the DC voltage value on the output side of the DC-DC power converter 5 and outputs it as a DC voltage feedback signal B to the power control means 15. The first current detector 8 is a sensor that detects a current to be measured in a non-contact manner using, for example, a Hall element that is a magnetoelectric conversion element, and is a direct current value on the output side of the DC-DC power converter 5. Or an overcurrent is detected and output to the power control means 15 as a DC current feedback signal C.

  The high-frequency power converter 9 is an inverter circuit, and is referred to as two pairs of semiconductor switching elements facing each other, for example, a pair of IGBTs (Q1 and Q4 switches) and IGBTs (Q2 and Q3 switches) (hereinafter referred to as a second switching element). ) Controls the conduction / cutoff between the collector and the emitter by a control signal (hereinafter referred to as a switching control signal) G input to the gate of the second switching element. That is, in the high-frequency power converter 9, the second switching element repeatedly turns on / off alternately, and the second DC power having a waveform voltage smoothed by the second smoothing capacitor 6 is converted into a substantially rectangular shape. It is a circuit for converting to a first AC power having a voltage of a wave AC waveform. That is, the high-frequency power converter 9 receives the second DC power, turns on / off the gate of the second switching element that is present by the switching control signal G, and converts the second DC power into the first AC power. And AC power is output to the high-frequency transformer 10.

  The high-frequency transformer 10 is a transformer composed of a primary winding 10p and a secondary winding 10s that are electromagnetically coupled to each other. Considering safety and environment for high-frequency AC power output from the high-frequency power converter 9 It is installed to do. The high-frequency transformer 10 inputs an AC voltage to the primary winding 10p, and an AC voltage proportional to the turn ratio between the primary winding 10p and the secondary winding 10s is applied to the secondary winding 10s by mutual electromagnetic induction. generate. The primary winding 10p of the high-frequency transformer 10 has a winding start connected to the emitter of the second switching element Q1 and the collector of Q3, and an end of winding connected to the emitter of the second switching element Q2 and the collector of Q4. The secondary winding 10 s of the high-frequency transformer 10 is connected to the load device 17. That is, the high-frequency transformer 10 receives the first AC power, converts the first AC power into second AC power that is electrically insulated from the first AC power, and outputs the second AC power to the load device 17. Thus, the high-frequency transformer 10 insulates the input commercial power supply from the AC power.

  The second voltage detector 11 detects an AC voltage value on the secondary side of the high-frequency transformer 10 and outputs the AC voltage value to the power control means 15 as an AC voltage feedback signal D. Similar to the first current detector 8, the second current detector 12 is a sensor that detects a current to be measured in a non-contact manner using a Hall element, and an AC current value on the secondary side of the high-frequency transformer 10. Is output to the power control means 15 and the oscillation control means 16 as an alternating current feedback signal E. The reactor 13 is an inductance device, and suppresses the current change rate of the output current on the secondary side of the high-frequency transformer 10. That is, the short circuit current based on the arc discharge generated in the load device 11 is suppressed.

  The DC control power supply 14 is a control constant voltage power supply, and supplies a DC constant voltage to the DC circuit of the power control means 15 and the oscillation control means 16. Here, a two-phase commercial power source is input from the commercial AC power source 2 and a DC constant voltage is output. Note that the DC control power supply 14 may output a DC constant voltage as a completely independent DC control power supply by using a power supply of a different system from the commercial AC power supply 2.

  The power control means 15 generates a gate control signal A for generating DC power output from the DC-DC power converter 5 based on a preset DC power command value, and the gate control signal A is converted to DC. -It outputs to DC power converter 5. Here, the DC power command value is a value that depends on the load device 17, and is a value determined by, for example, the size or material of the load. That is, the DC power output from the DC-DC power converter 5 has a value commensurate with the load such as the size and material of the load device 17. Further, the power control means 15 receives a DC voltage feedback signal B from the first voltage detector 7, a DC current feedback signal C from the first current detector 8, and an AC voltage feedback signal from the second voltage detector 11. D is input with the alternating current feedback signal E from the second current detector 12. The power control means 15 is configured to reduce the DC power when the AC power supplied to the load device 17 decreases and the AC power value becomes smaller than the DC power command value. Is reduced and generated to generate a gate control signal A, and the gate control signal A is output to the DC-DC power converter 5. Therefore, the DC-DC power converter 5 outputs DC power based on the decrease-corrected DC power command value, the DC voltage feedback signal B detected by the first voltage detector 7, and the first The DC current feedback signal C detected by the current detector 8 is fed back to the power control means 15.

  The oscillation control means 16 generates a switching control signal G for generating AC power output from the high frequency power converter 9 from the switching frequency and the dead band period, and outputs the switching control signal G to the high frequency power converter 9. To do. Further, the oscillation control means 16 receives the AC current feedback signal E from the second current detector 12 and based on the preset discharge voltage value and the DC power command value preset in the power control means 15. The current level command value in each of the steady mode and the start / restart mode (a value smaller than the arc current level command value for determining the arc detection) is calculated, and in each mode, the alternating current by the alternating current feedback signal E is calculated. The current level value is compared with the current level command value, and when the alternating current level value is large, the pulse of the switching control signal G is turned off and the switching of the high-frequency power converter 9 is cut off. In this case, the oscillation control means 16 performs cutoff control of the high-frequency power converter 9 continuously for each pulse of the switching control signal G.

[Configuration of Power Control Unit 15]
Next, the configuration of the power control unit 15 shown in FIG. 1 will be described in detail. FIG. 2 is a control block diagram showing the configuration of the power control means 15. The power control means 15 includes a power setting unit 21, a command calculator 22, a power control amplifier 23, a gate controller 24, a first feedback power calculator 25, a second feedback power calculator 26, and a power error controller 27. It has.

  The power setting unit 21 sets a DC power command value W, for example, 10 kW (kilowatt) for the DC-DC power converter 5 to generate DC power, and a command calculator 22, power error control as a DC power command signal F Output to the device 27 and the oscillation control means 16. The feedback power calculator 25 receives the DC voltage feedback signal B from the first voltage detector 7 and the DC current feedback signal C from the first current detector 8, and receives the DC feedback power value W1 (voltage value × current). Value) is calculated and output to the power control amplifier 23 as a DC power feedback signal. The feedback power calculator 26 receives an AC voltage feedback signal D from the second voltage detector 11 and an AC current feedback signal E from the second current detector 12, and receives an AC feedback power value W2 (voltage value × current). Value) is calculated and output to the power error controller 27 as an AC power feedback signal. The power error controller 27 receives the DC power command signal F from the power setter 21 and the AC power feedback signal from the feedback power calculator 26, and compares the DC power command value W with the AC feedback power value W2. Only when the AC feedback power value W2 is smaller than the DC power command value W (W2 <W), the difference value (W−W2) between them is calculated and output to the command calculator 22 as a difference signal.

  The command calculator 22 receives the DC power command signal F from the power setter 21, receives the difference signal from the power error controller 27, subtracts the difference value (W−W2) from the DC power command value W, and newly A new DC power command value W ′ is obtained and output to the power control amplifier 23 as a new DC current command signal.

  The power control amplifier 23 includes a command calculator 23-1 and a PID calculator 23-2. The command calculator 23-1 receives a new DC current command signal from the command calculator 22 and a DC power feedback signal from the feedback power calculator 25. The command calculator 23-1 receives the DC feedback power value W 1 from the new DC power command value W ′. Is subtracted to obtain a DC power deviation value and output to the PID calculator 23-2 as a deviation signal. The PID calculator 23-2 receives the deviation signal from the feedback power calculator 23-1, performs PID calculation, obtains a DC power correction command value, and outputs it to the gate controller 24 as a correction command signal. The gate controller 24 receives the correction command signal from the PID calculator 23-2, generates a gate control signal A as a pulse width command signal, and supplies it to the gate of the first switching element of the DC-DC power converter 5. Output.

  As described above, the power control means 15 generates the gate control signal A from the DC power command value suitable for the load device 17, controls the DC power of the DC-DC power converter 5, and is supplied to the load device 17. When the alternating current decreases and the alternating current power value is smaller than the direct current power command value, the direct current power command value is decreased, and the gate control signal A is generated from the decreased direct current power designated value, and the DC-DC power conversion Control is performed so that the DC power of the device 5 decreases. Thereby, when the current of the AC power supplied to the load device 17 decreases, the DC power decreases, and as a result, saturation of the DC voltage generated due to an error between the AC power value and the DC power command value, etc. Can be suppressed, and stable characteristics can be obtained.

[Configuration of Oscillation Control Unit 16]
Next, the configuration of the oscillation control means 16 shown in FIG. 1 will be described in detail. FIG. 3 is a control block diagram showing the configuration of the oscillation control means 16. The oscillation control means 16 includes an arc control means 30 and a pulse command calculation means 50. The arc control means 30 includes a process voltage setter 31, a current level calculator 32, a current level setter 33, a command selector 34, a rate time setter 35, an arc current reference value setter 36, and a hold / release signal generator 37. , A second comparator 38, a current-voltage converter 39, an isolation transformer 40, a differential amplifier 41, an absolute value converter 42, a first comparator 43, a cutoff signal generator 44, and a calculator 45. . Further, the pulse command calculation means 50 includes a switching frequency setting device 51, a dead band setting device 52, a switching command device 53, and a gate control / breaker 54.

  The process voltage setting unit 31 presets a discharge voltage value determined by the size of the load device 17 and the process, and outputs a discharge voltage signal to the current level calculator 32. The current level calculator 32 receives the discharge voltage signal from the process voltage setter 31 and the DC power command signal from the power control means 15, respectively, and calculates the current value I1 by dividing the DC power command value by the discharge voltage value. It outputs to the current level setting device 33 as a current level reference signal. For example, when the discharge voltage value is 500 VAC and the DC power command value is 10 kW, the current value I1 is 200A.

  When the current level reference signal is input from the current level calculator 32, the current level setting unit 33 divides the current value I1 by the winding ratio (10p: 10s) of the high-frequency transformer 10 to obtain a current value I2, and a current level command The signal is output to the command selector 34 as a signal. For example, when the winding ratio is 1: 1.5 and the current value I1 is 200A, the current value I2 is 133A.

  The command selector 34 receives a current level command signal from the current level setter 33 and a mode signal from a mode commander (not shown), and multiplies a preset ratio to obtain a current level command value corresponding to the mode. Here, the mode commander (not shown) indicates whether the load device 17 is operating in the steady mode, whether the load device 17 is operating in the start-up mode when the load device 17 is started, or by arc discharge. It is determined whether the system is operating in the restart mode at the time of startup of the device after the shut-off, and mode information of either the steady mode or the start / restart mode is output to the command selector 34 as a mode signal. The command selector 34 is preset with a ratio for each mode. For example, in the steady mode, the ratio is 1, and in the start / restart mode, the ratio is 0.5. In the start / restart mode, the arc discharge is caused by the state of the electrode of the load device 17 being heated. Considering that it is likely to occur again, a ratio lower than the ratio in the normal mode is set. When the mode signal is the steady mode, the command selector 34 multiplies the current value I2 (133A) and the ratio (1) to obtain a new current value I3 (133A). When the mode signal is the start / restart mode, the current value I2 (133A) is multiplied by the ratio (0.5) to obtain a new current value I3 (66.5A). Then, the command selector 34 outputs the obtained current value I3 to the rate time setter 35 as a current level command signal corresponding to the mode.

  The rate time setting unit 35 receives a current level command signal corresponding to the mode from the command selector 34 and a mode signal from a mode command unit (not shown), and is set in advance when the mode is the start / restart mode. The new current value I4 is obtained so as to gradually rise from the current value I3 in the start / restart mode to the current value I3 in the steady mode according to the rate time, and is output to the first comparator 43 as a current level command signal. When the mode is the steady mode, the input current value I3 is used as it is as a new current value I4. In the start / restart mode, when the peak value of the pulse waveform of the AC current supplied to the load device 17 increases slightly as in (4) of FIG. The rate time setting unit 35 can generate a current level command value suitable for the temporary increase. As a result, stable start-up characteristics can be obtained at the time of start-up of the load device 17 and at the time of restart after the arc discharge occurs.

  On the other hand, as shown in FIG. 4, the current-voltage converter 39 includes, for example, a resistor 39-1 and a capacitor 39-2, and a resistor 39-1 is arranged in series with the output terminal of the second current detector 12. The capacitor 39-2 is arranged in parallel with the resistor 39-1. The current-voltage converter 39 receives the alternating current feedback signal E from the second current detector 12, converts the current into a voltage, and outputs the voltage signal to the differential amplifier 41 via the isolation transformer 40.

  As shown in FIG. 4, the differential amplifier 41 includes resistors 44-1 to 44-4 and an operational amplifier 44-5. The differential amplifier 41 receives a voltage signal from the isolation transformer 40, differentially amplifies it, and outputs an output voltage value signal. Is output to the absolute value converter 42. The resistors 44-1 to 44-4 are set in advance so that the output voltage value is equal to the AC feedback current value of the AC current feedback signal E. For example, if the AC feedback current value is 1 A, the output voltage value is set to 1V. Thereby, by outputting a signal of an output voltage value from the output terminal of the differential amplifier 41, the AC feedback current value can be known. The insulation transformer 40 and the differential amplifier 41 are provided to improve noise tolerance, and may be omitted as necessary.

  The absolute value converter 42 receives the output voltage value signal from the differential amplifier 41, calculates the absolute value of the output voltage value, and outputs the absolute value signal (current level signal) as the calculation result to the first comparator. 43 and the second comparator 38. Thereby, the absolute value converter 42 can output the input positive / negative signal as a positive polarity signal.

  The first comparator 43 receives the current level signal from the absolute value converter 42 and the current level command signal from the rate time setter 35, respectively, and the current level value and the current level command value in the steady mode (current value I4). ) Or the current level command value (current value I4) in the start / restart mode, and when the current level value is equal to or exceeds the current level command value, the control signal is output to the cutoff signal generator 44. When receiving the control signal from the first comparator 43, the cutoff signal generator 44 outputs the control cutoff signal to the calculator 45. Thereby, the switching control signal G output from the pulse command calculating means 50 is turned OFF, and the power supply from the high-frequency power converter 9 to the load device 17 is interrupted. Since such power supply cutoff processing is performed for each pulse of the switching control signal G, high-speed continuous processing can be realized.

  On the other hand, the arc current reference value setting unit 36 sets an arc reference value that serves as a reference for determining that arc discharge is occurring in the load device 17. The second comparator 38 compares the arc reference value from the arc current reference value setter 36 with the current level value from the absolute value converter 42, and the current level value is equal to or exceeds the arc reference value. In addition, the control signal is output to the hold / release signal generator 37.

  When the control signal is input from the second comparator 38, the hold / release signal generator 37 outputs an arc interruption signal to the calculator 45 and holds the output. Thereby, the switching control signal G output from the pulse command calculating means 50 is turned OFF, and the power supply from the high-frequency power converter 9 to the load device 17 is interrupted. Then, after the predetermined time has elapsed, the holding of the output of the arc interruption signal is released. Thereby, the power supply to the load device 17 is resumed.

  The arc current reference value setter 36, the hold / release signal generator 37, and the arc current reference value setter 36 are means for detecting arc discharge and outputting an arc interruption signal. 1 is detected, the first comparator 43 and the cutoff signal generator 44 output a control cutoff signal. That is, the arc reference value is set to a level higher than the current level command value in the normal mode and the start / restart mode, and the arc current reference value setter 36, the hold / release signal generator 37, and the second comparator 38 are set. Is limited to a backup function. Therefore, the arc control means 30 does not necessarily need to include the arc current reference value setter 36, the hold / release signal generator 37, and the arc current reference value setter 36.

  The arithmetic unit 45 receives the control cutoff signal from the cutoff signal generator 44 and the arc cutoff signal from the hold / release signal generator 37, performs an OR operation, and outputs the cutoff signal to the gate control / breaker 54. To do.

  FIG. 5 is a diagram showing a current waveform of the alternating current feedback signal E and a pulse waveform of the switching control signal G detected by the second current detector 12. Although the current waveform of the AC current feedback signal E is shown separately on the + side and the − side, in practice, the first comparator 43 and the second comparator 38 perform absolute value comparison processing. When the first comparator 43 determines that the + side current level value of the AC current feedback signal E is equal to or exceeds the steady level + side (+ side current level command value) in the steady mode (1), The cutoff signal generator 44 outputs a control cutoff signal and turns off the pulse of the switching control signal G (2). Similarly, when it is determined that the negative current level value of the alternating current feedback signal E is equal to or lower than the steady level negative side (negative current level command value) (3), a control cutoff signal is output and switching control is performed. The pulse of the signal G is turned off (4).

  Further, the second comparator 38 holds / releases when it is determined that the + side current level value of the AC current feedback signal E is equal to or exceeds the arc level + side (+ side arc reference value) (5). The signal generator 37 outputs an arc interruption signal and turns off the pulse of the switching control signal G (6). Thereafter, as will be described later, the switching control signal G gradually increases in pulse width from the time after a predetermined time has elapsed until it reaches the pulse width in the steady mode. In the startup / restart mode, the first comparator 43 has the negative current level value of the alternating current feedback signal E equal to or lower than the startup / restart level negative side (negative current level command value). If it is determined (7), the cutoff signal generator 44 outputs a control cutoff signal and turns off the pulse of the switching control signal G (8). The same process is performed for the positive current level value of the AC current feedback signal E. As described above, in the startup / restart mode, the interruption process is performed for each pulse of the switching control signal G, so that continuous high-speed processing is possible.

  Returning to FIG. 3, the switching frequency setting unit 51 of the pulse command calculating means 50 determines the switching frequency command value of the switching control signal G for turning on / off the gate of the second switching element in the high-frequency power converter 9. Set. The dead band setting unit 52 sets a dead band period provided to prevent the P side and the N side of the switching control signal G from being short-circuited when switching the gate of the second switching element.

  The switching command unit 53 inputs the switching frequency command value from the switching frequency setting unit 51 and the dead band period from the dead band setting unit 52, calculates the original pulse width from the switching frequency command value, The dead band period is subtracted from the pulse width to obtain a steady pulse width as shown in FIG. In the steady mode, the switching control signal G is generated with a pulse having this steady pulse width (constant pulse width). When the power supply is restored after the arc discharge occurs (in the start / restart mode), the switching control signal G is used by using the preset initial pulse width and rate time and the calculated steady pulse width. Is generated. Specifically, the switching command unit 53 has a pulse width sequence in which the pulse width of the switching control signal G gradually increases from the initial pulse width until the rate time elapses and becomes the steady pulse width. Is output to the gate control / breaker 54 as a switching command signal.

  The gate control / breaker 54 receives a switching command signal from the switching commander 53 and a blocking signal from the computing unit 45, generates a switching control signal G based on the pulse width train of the switching command signal, and generates a high-frequency power converter. 9 to the gate of the second switching element. When a cutoff signal is input, the pulse of the switching control signal G is turned off.

[Operation / Arc prevention]
Next, an arc prevention method among the operations of the AC power supply device 1 shown in FIG. 1 will be described. FIG. 7 is a flowchart showing the processing procedure of the arc prevention method in the AC power supply apparatus 1. First, the current level setting unit 33 calculates a value calculated using the discharge voltage value from the process voltage setting unit 31 and the DC power command value from the power control means 15 and the winding ratio (10p: 10 s) of the high-frequency transformer 10. ) To set a current level command value (step S701). Then, the command selector 34 and the rate time setter 35 multiply the current level command value by the ratio set for each operation mode in accordance with the operation mode of the load device 17 to obtain the current level command value in the steady mode or A current level command value for the start / restart mode is set (step S702). In this case, in the start / restart mode, the new current level command value is gradually increased from the current level command value in the start / restart mode to the current level command value in the steady mode at a preset rate time. Set.

  Then, the first comparator 43 compares the current level value corresponding to the alternating current feedback signal E from the second current detector 12 with the current level command value set in step 702 (step S703). When the current level value is equal to or exceeds the current level command value, the cutoff signal generator 44 is caused to output a control cutoff signal (step S704). The gate control / breaker 54 turns off the pulse of the switching control signal G when the control cutoff signal is output in step 704 (step S705). In this way, the process for shutting off the power supply to the load device 17 is performed. Then, the process returns to step 702. In this case, the pulse of the switching control signal G is turned off and the pulse is turned on when the next pulse of the switching control signal G is output. However, in steps 702 to 704, the current level value is equal to the current level command value or When the upper control cutoff signal is output again, in step 705, the pulse of the switching control signal G is turned off again. Since such power supply cutoff processing is performed for each pulse of the switching control signal G, high-speed continuous processing can be realized.

[Operation / DC voltage saturation suppression]
Next, of the operations of the AC power supply device 1 shown in FIG. 1, a DC voltage saturation suppression method will be described. FIG. 8 is a flowchart showing the processing procedure of the DC voltage saturation suppression method in the AC power supply apparatus 1. First, the feedback power calculator 25 calculates a DC feedback power value based on the DC voltage feedback signal B and the DC current feedback signal C (step S801). Further, the feedback power calculator 26 calculates an AC feedback power value based on the AC voltage feedback signal D and the AC current feedback signal E (step S802). Then, the power error controller 27 compares the AC feedback power value with the DC power command value (step S803), and when the AC feedback power value is smaller than the DC power command value, the DC power command value and the AC feedback power. The difference with the value is subtracted and corrected from the DC power command value to calculate a new DC power command value, and the DC feedback power value is subtracted from the new DC power command value and amplified (step S804). On the other hand, when the AC feedback power value is greater than or equal to the DC power command value, the DC power command value is maintained (step S805). Then, the gate controller 24 generates the gate control signal A based on the DC power command value (step S806). Thereby, when the current of the AC power supplied to the load device 17 decreases, the DC power of the DC-DC power converter 5 decreases, and as a result, an error between the AC power value and the DC power command value. Saturation of the DC voltage generated by the above can be suppressed, and stable characteristics can be obtained.

It is a control block diagram which shows the structure of the alternating current power supply device which concerns on embodiment of this invention. It is a control block diagram which shows the structure of an electric power control means. It is a control block diagram which shows the structure of an oscillation control means. It is a figure which shows the structure of a current-voltage converter, an insulation transformer, and a differential amplifier. FIG. 4 is a diagram showing a current waveform of an alternating current feedback signal E and a pulse waveform of a switching control signal G. It is a figure which shows the output waveform of a switching command device. It is a flowchart figure which shows the process sequence of the arc prevention method in the alternating current power supply device which concerns on this invention. It is a flowchart figure which shows the process sequence of the alternating current power stabilization method in the alternating current power supply device which concerns on this invention. It is a figure which shows a structure of the conventional power supply device. It is a figure which shows the signal waveform of each part in the conventional power supply device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply device 2 Commercial AC power supply 3 AC-DC rectifier 4 1st smoothing capacitor 5 DC-DC power converter 6 2nd smoothing capacitor 7 1st voltage detector 8 1st current detector 9 High frequency Power converter 10 High-frequency transformer 11 Second voltage detector 12 Second current detector 13 Reactor 14 DC control power supply 15 Power control means 16 Oscillation control means 17 Load device 21 Power setting unit 22 Command calculator 23 Power control amplifier 23-1 Command calculator 23-2 PID calculator 24 Gate controller 25 First feedback power calculator 26 Second feedback power calculator 27 Power error controller 30 Arc control means 31 Process voltage setter 32 Current level calculator 33 Current level setter 34 Command selector 35 Rate time setter 36 Arc current reference value setter 37 Holding / release signal generator 38 Second Comparator 39 Current-voltage converter 39-1 Resistor 39-2 Capacitor 40 Insulating transformer 41 Differential amplifier 41-1 to 41-4 Resistor 41-5 Operational amplifier 42 Absolute value converter 43 First comparator 44 Cut off Signal generator 45 Calculator 50 Pulse command calculator 51 Switching frequency setter 52 Dead band setter 53 Switching commander 54 Gate controller / breaker 71 DC controller 72 Smoothing circuit 73 Inverter switching unit 74 Step-up transformer 75 Rectifier 76 Processing Device main body 77 Thyristor control unit 78 Inverter control unit 79 Current transformer 80 Current detection circuit 81 Temperature detector A Gate control signal B DC voltage feedback signal C DC current feedback signal D AC voltage feedback signal E AC current feedback signal F DC power command signal G Switching control signal

Claims (5)

A power supply that converts commercial AC power to high-frequency AC power and supplies the AC power to a load device, in an AC power supply device that prevents the occurrence of arc discharge.
A DC-DC power converter that converts the DC power rectified from the commercial AC power into a new DC power by controlling the gate of the switching element by a gate control signal;
A high-frequency power converter that converts the converted direct-current power into high-frequency alternating-current power by controlling a gate of a switching element by a switching control signal;
A current detector for detecting an AC current value of AC power supplied to the load device;
Oscillation control means for outputting a switching control signal having a pulse for controlling the gate of the switching element of the high-frequency power converter to the high-frequency power converter;
The oscillation control means generates a cutoff signal based on a current level command value smaller than an arc reference current value for detecting arc discharge and the detected AC current value, and performs switching control based on the cutoff signal. An AC power supply device characterized in that the pulse of the signal is turned off and the supply of AC power to the load device is stopped.   The oscillation control means, in a steady mode that operates without generating arc discharge, is based on a predetermined current level command value smaller than an arc reference value for detecting arc discharge and the alternating current value. In the start mode for starting AC power supply to the load device or in the restart mode after the occurrence of arc discharge, a value smaller than an arc reference current value for detecting arc discharge, and the steady mode 2. The AC power supply apparatus according to claim 1, wherein a cutoff signal is generated based on a current level command value smaller than a current level command value and the AC current value. Furthermore, a voltage detector that detects an AC voltage value of AC power supplied to the load device;
Power control means for generating a gate control signal based on a DC power command value suitable for the load device, and outputting the gate signal to the DC-DC converter;
The power control means calculates an AC power value from the AC voltage value and the AC current value, and reduces the DC power command value when the AC power value is smaller than the DC power command value. The AC power supply device according to claim 1 or 2. In an arc prevention method in an AC power supply device that converts commercial AC power to high-frequency AC power and supplies the AC power to a load device.
AC-DC rectification step of rectifying the commercial AC power into DC power;
DC-DC power conversion step of converting the rectified DC power into new DC power by controlling the gate of the switching element by a gate control signal;
A high-frequency power conversion step of converting the converted direct-current power into high-frequency alternating-current power by controlling a gate of a switching element by a switching control signal;
A current detection step of detecting an alternating current value of the alternating current power supplied to the load device;
When generating a switching control signal having a pulse for controlling the gate of the switching element in the high-frequency power conversion step,
A cutoff signal is generated based on a current level command value smaller than an arc reference current value for detecting arc discharge and the detected AC current value, and the pulse of the switching control signal is turned off by the cutoff signal. And an oscillation control step of stopping the supply of AC power to the load device. A voltage detection step of detecting an AC voltage value of AC power supplied to the load device;
When generating a gate control signal based on a DC power command value commensurate with the load device,
An AC power value is calculated from the AC voltage value and the AC current value,
5. The arc prevention method for an AC power supply apparatus according to claim 4, further comprising a power control step of decreasing the DC power command value when the AC power value is smaller than the DC power command value.

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