JP6628316B2 - Test power supply - Google Patents

Description

  The present invention relates to a test power supply device, and more particularly, to an improvement of a test power supply device that supplies power to a device to be inspected that is supplied with AC power of a fundamental frequency.

  Examples of power devices supplied with AC power of a fundamental frequency from a commercial power supply include a PCS (Power Conditioning System) for converting the output of a solar cell or a fuel cell. This type of power device is required to be compatible with a tolerance test for voltage fluctuation of a commercial power supply. For example, EMC (Electro-Magnetic Compatibility) test standard requires immunity (electromagnetic immunity) to a composite wave in which voltage waveforms of various frequencies are superimposed as interference waves on a voltage waveform of a fundamental frequency. . In the tolerance test, it is determined whether or not the power device operates normally even if the voltage waveform supplied from the power device is distorted.

  A test power supply for performing the above-described tolerance test is called an AC simulator, and a power supply of a linear amplifier system is known. A power supply device of the linear amplifier type is a device that adds a harmonic signal generated by a signal generator to a signal of a fundamental frequency and amplifies electric power by using an amplifying action of an active element. The rated output is several kVA at most.程度 about several tens kVA. For this reason, there was a problem that it was not suitable for the resistance test of a large-capacity PCS.

  Therefore, it is conceivable to perform a tolerance test using an inverter type power supply device. The inverter type power supply device is a device that generates a synthetic wave by operating an inverter including a plurality of switching elements at a predetermined switching frequency, and can easily increase the capacity. For example, since the fundamental frequency is 50 Hz or 60 Hz, a switching frequency of several kHz to several tens of kHz is used. However, in the EMC test standard described above, it is necessary to generate a higher-order harmonic such as 40 times the fundamental frequency, and when a higher-order harmonic is generated at a switching frequency of several kHz to several tens of kHz, the resolution is insufficient. There is a problem that the voltage waveform is distorted.

  On the other hand, increasing the switching frequency can prevent distortion of the higher-order harmonic waveform, but increasing the switching frequency has the problem of increasing power loss due to switching.

  Therefore, in order to generate a power supply in which an interference wave is superimposed on a fundamental wave, it is conceivable to use an inverter that generates a fundamental wave and an inverter that generates an interference wave. By operating the inverter for interference waves at a higher switching frequency than the inverter for fundamental waves, it is possible to suppress the increase in power loss due to the switching operation and prevent distortion of the higher-order harmonic waveform. it can.

  In order to superimpose the interference wave on the fundamental wave, a configuration in which the output of the inverter for the fundamental wave and the output of the inverter for the interference wave are coupled by a transformer can be considered. However, in the case of such a transformer coupling, if the disturbance wave inverter is stopped when the disturbance wave inverter breaks down, a large current flowing from the fundamental wave inverter to the load through the transformer causes the disturbance wave through the transformer. There is a problem that an overvoltage is applied to the inverter for use.

  The present invention has been made in view of the above circumstances, and it is possible to prevent a high-order harmonic waveform from being distorted while suppressing an increase in power loss due to a switching operation. An object of the present invention is to provide a test power supply device that can prevent an overvoltage from being applied to the inverter via a transformer when the inverter fails.

  A test power supply device according to a first aspect of the present invention is a test power supply device having a fundamental frequency, comprising: a low-band inverter that generates a fundamental wave having a voltage waveform of the fundamental frequency; A high-band inverter that generates an interference wave having a voltage waveform of a band test frequency, the low-band inverter and the high-band inverter are connected to a primary coil and a secondary coil, respectively, and the interference wave is superimposed on the fundamental wave. A transformer coupling circuit, a bidirectional thyristor connected in parallel to the primary coil of the transformer coupling circuit and forming a bypass path in a conductive state, failure detection means for detecting a failure of the high-bandwidth inverter, and the failure detection Thyristor control means for switching the bidirectional thyristor from the cutoff state to the conduction state based on the detection result of the means; Provided.

  According to such a configuration, power amplification is performed by the switching operation of the low-band inverter and the high-band inverter, so that it is easy to increase the capacity. In addition, since an interfering wave is generated by the high-band inverter, it is possible to prevent distortion of a high-order harmonic waveform. In addition, since the transformer coupling circuit superimposes the interference wave on the fundamental wave, an increase in power loss due to the switching operation can be suppressed as compared with the case where power amplification is performed by one inverter. Further, when a failure of the high-bandwidth inverter is detected, the bypass path passing through the bidirectional thyristor can be quickly formed by switching the bidirectional thyristor from the cutoff state to the conduction state. Therefore, when the high-band inverter for the disturbance wave fails, it is possible to prevent a large current flowing from the low-band inverter for the fundamental wave to the load from applying an overvoltage to the high-band inverter via the transformer. it can.

  The test power supply device according to the second aspect of the present invention further includes, in addition to the above configuration, an inverter control means for stopping the high band inverter after the bidirectional thyristor is switched to the conductive state by detecting a failure. Be composed.

  With such a configuration, it is possible to reliably prevent an overvoltage from being applied to the high-bandwidth inverter via the transformer coupling circuit due to a large current flowing from the low-bandwidth inverter to the load via the transformer coupling circuit.

  According to a third aspect of the present invention, in addition to the above configuration, the test power supply device further comprises a switch connected in parallel to the primary coil of the transformer coupling circuit to form a bypass path in a closed state; Switch control means for switching between an open state and a closed state, the low-band inverter generates a composite wave in which a voltage waveform of a low-band test frequency is superimposed on the fundamental wave, and the switch control means, When changing from the power supply of the low band test frequency to the power supply of the high band test frequency, the switch is switched from the closed state to the open state to cut off the bypass path.

  According to such a configuration, by switching the switch, the power supply composed of the composite wave in which the voltage waveform of the low-band test frequency is superimposed on the fundamental wave and the interfering wave of the high-band test frequency are superimposed on the fundamental wave The power supply can be arbitrarily selected. Further, by using the switch for switching between the power supply of the low band test frequency and the power supply of the high band test frequency, the durability can be secured as compared with the case where a semiconductor switching element such as a bidirectional thyristor is used.

  In the test power supply device according to a fourth aspect of the present invention, in addition to the above configuration, the switch control means switches the switch from an open state to a closed state based on a detection result of the failure detection means, The thyristor control means is configured to switch the bidirectional thyristor from the conductive state to the cutoff state after the switch is switched to the closed state. According to such a configuration, since the use of the bidirectional thyristor is limited to a short time, the current withstand capability can be suppressed.

  In the test power supply device according to a fifth aspect of the present invention, in addition to the configuration, the inverter control means causes the low-band inverter to generate the composite wave when the power supply of the low-band test frequency is generated. Stopping the high-band inverter and generating a power supply of the high-band test frequency, causing the low-band inverter to generate the fundamental wave, and causing the high-band inverter to generate the interfering wave, When the power supply of the high-band test frequency is changed to the power supply of the fundamental wave, the high-band inverter is stopped after the switch is switched from the open state to the closed state.

  According to such a configuration, when changing from the power supply of the high-band test frequency to the power supply of the fundamental wave, the switch is switched from the open state to the closed state before the high-band inverter is stopped. A large current flowing from the inverter to the load via the transformer coupling circuit can prevent an overvoltage from being applied to the high-bandwidth inverter via the transformer coupling circuit.

  In the test power supply device according to a sixth aspect of the present invention, in addition to the above configuration, the failure detection means detects a failure of the high bandwidth inverter based on an output current, an output voltage or a temperature of the high bandwidth inverter. It is configured as follows. According to such a configuration, it is possible to detect a failure of the high-bandwidth inverter based on a sudden change in output current or output voltage or a rise in temperature.

  ADVANTAGE OF THE INVENTION According to this invention, while suppressing the increase of the power loss by a switching operation, it can prevent that a high-order harmonic waveform produces distortion, and when an inverter for an interference wave fails, a transformer is set. It is possible to prevent an overvoltage from being applied to the inverter.

FIG. 1 is a system diagram showing a configuration example of a test power supply device 1 according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration example of a power generation unit 12 in FIG. 1. FIG. 3 is a diagram illustrating details of a high-band inverter 123 and a transformer coupling circuit 124 in FIG. 2. FIG. 3 is a block diagram illustrating a configuration example of an inverter control circuit 129 of FIG. 2. FIG. 3 is a diagram illustrating an operation example of the power generation unit 12 of FIG. 2. FIG. 2 is a block diagram illustrating an example of a functional configuration in the information processing terminal 11 of FIG. 1. 7 is a flowchart illustrating an operation example of the information processing terminal 11 in FIG. 6 at the start of a high bandwidth test. 7 is a flowchart illustrating an operation example of the information processing terminal 11 in FIG. 6 at the end of the high bandwidth test. 7 is a flowchart illustrating an operation example when a failure is detected in the information processing terminal 11 of FIG. 6.

<Test power supply 1>
FIG. 1 is a system diagram showing one configuration example of a test power supply device 1 according to an embodiment of the present invention. FIG. 1 shows a test power supply device 1 connected to a PCS (Power Conditioning System) 2 to be inspected. The PCS 2 is a power conversion device that converts DC power generated by a solar cell or a fuel cell into AC power, and outputs the AC power to a power system at a stable voltage and frequency.

  The test power supply device 1 is an AC simulator that supplies power to a device under test that is supplied with AC power having a basic frequency f0. Voltage waveforms of various frequencies are superimposed on the voltage waveform of the basic frequency f0 as interference waves. Various resistance tests are performed by generating the synthesized waves. The test power supply device 1 generates a composite wave based on a test frequency instruction from the information processing terminal 11 that specifies a fundamental frequency f0 and a test frequency for a tolerance test, and supplies the PCS 2 with a power supply. And a power supply generating unit 12 for applying the voltage.

  The information processing terminal 11 is, for example, a personal computer that operates based on an application program for a resistance test. The information processing terminal 11 specifies a low-band test frequency f1 lower than the threshold frequency wave fts1 or generates a test frequency instruction for specifying a high-band test frequency f2 equal to or higher than the threshold frequency fts2. Output to

  Each of the threshold frequencies fts1 and fts2 is a fixed value of a frequency higher than the fundamental frequency f0, and is determined in advance. The threshold frequency fts1 is equal to or higher than the threshold frequency fts2. The low-band test frequency f1 and the high-band test frequency f2 are specified based on a user operation or automatically specified according to a predetermined test schedule.

  The basic frequency f0 corresponds to the frequency of the commercial power supply, for example, f0 = 50 Hz. The information processing terminal 11 designates the low-band test frequency f1 and the high-band test frequency f2 as threshold frequencies fts1 and fts2 within a range of 12 times or less the fundamental frequency f0. The threshold frequencies fts1 and fts2 are, for example, fts1 = fts2, and nine times the fundamental frequency f0, that is, fts1 and fts2 = 450 Hz are used.

  The low band test frequency f1 is specified within a range of 0.33 times or more and less than 9 times the fundamental frequency f0. On the other hand, the high band test frequency f2 is specified within a range from 9 times to 40 times the basic frequency f0. By employing such a configuration, it is possible to perform various resistance tests defined by the EMC test standards.

  For example, an individual harmonic test, an interharmonic test, and a frequency sweep test can be performed. The individual harmonic test is a tolerance test in which harmonics from the second to the 40th are sequentially superimposed. The inter-harmonic test is a tolerance test in which a voltage waveform that is a non-integer multiple of the fundamental frequency f0 is called an inter-harmonic, and the inter-harmonic is superimposed. The frequency sweep test is a tolerance test in which harmonics from the 0.33 order to the 40th order are superimposed stepwise or continuously. If the basic frequency f0 is f0 = 60 Hz, 540 Hz is used for the threshold frequencies fts1 and fts2.

  The power generation unit 12 is an inverter unit that generates a desired AC voltage as a power source by using power supplied from the commercial power source 3. The commercial power supply 3 supplies AC power having a frequency of 50 Hz and an effective value of voltage of 420 V to the power generation unit 12, for example, in a three-phase three-wire system.

<Power generation unit 12>
FIG. 2 is a diagram showing a configuration example of the power generation unit 12 of FIG. The power generation unit 12 includes a converter 121, a low-band inverter 122, a high-band inverter 123, a transformer coupling circuit 124, a switch 125, an output terminal 126, a converter control circuit 127, inverter control circuits 128 and 129, and ammeters 131 and 132. , Voltmeters 133 and 134 and a bidirectional thyristor 135.

  The converter 121 is a converter that generates a DC voltage using the commercial power supply 3, and includes a plurality of switching elements, for example, an IGBT (Insulated Gate Bipolar Transistor). The converter 121 converts an AC voltage input from the commercial power supply 3 into a DC voltage, and outputs the DC voltage to the low-band inverter 122 and the high-band inverter 123. Each switching element of converter 121 performs switching by gate drive signal GS. The DC voltage output from converter 121 is, for example, 650V.

  The low-band inverter 122 is a switching-type converter that converts a DC voltage input from the converter 121 into a low-band AC voltage and outputs the output from an output terminal 126 via a transformer coupling circuit 124 or a switch 125. , For example, an IGBT. Each switching element of the low-band inverter 122 switches according to the gate drive signal GS1.

  The low-band inverter 122 operates at a predetermined switching frequency fs1, for example, fs1 = 7 kHz, generates a fundamental wave composed of a voltage waveform of the fundamental frequency f0, or generates a voltage waveform of the low-band test frequency f1 on the fundamental wave. Generates a composite wave superimposed as an interference wave. The voltage level of the interfering wave superimposed on the fundamental wave by the low-band inverter 122 is about 0 to several tens of percent of the voltage level of the fundamental wave. Note that the switching frequency fs1 may be a frequency exceeding several kHz, for example, tens of kHz, specifically, 16 kHz to 18 kHz.

  Further, the low-band inverter 122 generates a composite wave in which a harmonic of an integral multiple of the fundamental frequency f0 is superimposed as an interfering wave, or an interharmonic of a non-integer multiple of the fundamental frequency f0 is superimposed as an interfering wave. . The inter-order harmonic includes a voltage waveform that is less than one time the fundamental frequency f0.

  The high-band inverter 123 is a switching converter that converts a DC voltage input from the converter 121 to a high-band AC voltage and outputs the converted AC voltage to the transformer coupling circuit 124, and includes a plurality of switching elements. Each switching element of the high-bandwidth inverter 123 switches according to the gate drive signal GS2.

  The high-band inverter 123 operates at a switching frequency fs2 higher than that of the low-band inverter 122, for example, fs2 = 42 kHz, and generates an interference wave having a voltage waveform of the high-band test frequency f2. Further, the high-band inverter 123 generates a harmonic that is an integral multiple of the fundamental frequency f0 or an inter-order harmonic that is a non-integer multiple of the fundamental frequency f0 as an interference wave.

  The high-band inverter 123 has a smaller output than the low-band inverter 122. For example, while the output of the low-band inverter 122 is about 800 kVA, the output of the high-band inverter 123 is about 150 kVA, which is 1/5 or less of the low-band inverter 122.

  The transformer coupling circuit 124 is a transformer circuit for superimposing an interference wave generated by the high-band inverter 123 on a fundamental wave generated by the low-band inverter 122. The low-band inverter 122 and the high-band inverter 123 Connected to the primary coil and the secondary coil, respectively. The voltage level of the interfering wave superimposed on the fundamental wave by the transformer coupling circuit 124 is about 0 to several tens of percent of the voltage level of the fundamental wave.

  The switch 125 is a switch of an electromagnetic switching system that conducts when outputting a power supply of the low band test frequency f1 and shuts off when outputting a power supply of the high band test frequency f2, and is connected in parallel to the transformer coupling circuit 124. Is done. The switch 125 is switched between an open state (blocked state) and a closed state (conductive state) in response to a switching drive signal KH from the information processing terminal 11.

  The bidirectional thyristor 135 is a semiconductor switching element that conducts when a failure of the high-bandwidth inverter 123 is detected, is configured by connecting two thyristors in antiparallel, and is connected to the transformer coupling circuit 124 in parallel. . The bidirectional thyristor 135 is switched between a cutoff state and a conduction state by a gate drive signal GK from the information processing terminal 11.

  The ammeter 131 is a current detector that detects a load current Iout flowing through a load connected to the output terminal 126 and outputs a detected value to the inverter control circuits 128 and 129, and includes a low-band inverter 122 and a transformer coupling circuit 124. And placed between. The load current Iout is an output current of the low-band inverter 122.

  The ammeter 132 is a current detector that detects the output current Iinv of the high-band inverter 123 and outputs the detected value to the inverter control circuit 129, and is arranged between the high-band inverter 123 and the transformer coupling circuit 124.

  The voltmeter 133 is a voltage detector that detects the output voltage Vout of the low-band inverter 122 and outputs the detected value to the inverter control circuit 128, and is disposed between the ammeter 131 and the transformer coupling circuit 124. In the voltmeter 133, the primary coil and the secondary coil are each delta-connected to each phase of AC.

  The voltmeter 134 is a voltage detector that detects the output voltage Vinv of the high-bandwidth inverter 123 and outputs the detected value to the inverter control circuit 129, and is arranged in parallel with the primary coil of the transformer coupling circuit 124. In the voltmeter 134, the primary coil is star-connected to each phase of AC, and the secondary coil is delta-connected to each phase of AC.

  Converter control circuit 127 is a control circuit for controlling converter 121, generates gate drive signal GS, and outputs it to converter 121. The inverter control circuit 128 is a control circuit that controls the low-bandwidth inverter 122 based on a test frequency instruction from the information processing terminal 11, generates a gate drive signal GS1 with reference to the load current Iout and the output voltage Vout, Output to low-band inverter 122.

  The inverter control circuit 128 performs feedback control of the low-band inverter 122 based on an error between a command value for the load current Iout and a detected value of the load current Iout by the ammeter 131. By the feedback control on the low-band inverter 122, the desired load current Iout can be output from the low-band inverter 122.

  The inverter control circuit 129 is a control circuit that controls the high-bandwidth inverter 123 based on a test frequency instruction from the information processing terminal 11, and refers to the load current Iout, the output current Iinv, and the output voltage Vinv to control the gate drive signal GS2. Is generated and output to the high-bandwidth inverter 123.

  This inverter control circuit 129 controls the high-bandwidth inverter 123 based on the load current Iout. That is, the inverter control circuit 129 performs feedforward control of the high-bandwidth inverter 123 using the detected value of the load current Iout by the ammeter 131 as a current command value.

  Since the high-bandwidth inverter 123 is controlled based on the load current Iout output to the PCS 2 to be inspected, an output current corresponding to the load current Iout can be generated in the primary coil of the transformer coupling circuit 124. In particular, the output current corresponding to the command value for the load current Iout can be generated in the primary coil of the transformer coupling circuit 124 by feedforward control of the high-bandwidth inverter 123.

  In addition, when outputting the power of the low-band test frequency f1, the inverter control circuit 129 switches the switch 125 to the closed state (on state) to make the bypass path to the transformer coupling circuit 124 conductive, and The band inverter 123 is stopped. On the other hand, the inverter control circuit 129 operates the high-bandwidth inverter 123 and then switches the switch 125 to an open state (off-state) when outputting the power of the high-bandwidth test frequency f2. Is interrupted, and the inverter control circuit 128 is instructed to select a fundamental wave.

  FIG. 3 is a diagram showing details of the high-bandwidth inverter 123 and the transformer coupling circuit 124 of FIG. The high-band inverter 123 includes six switching elements 4 and six freewheel diodes 5, and converts a DC input from the converter 121 into a three-phase three-wire AC voltage. The effective value of the voltage is, for example, 360V.

  As the switching element 4, a transistor with small power loss due to the switching operation, for example, an FET (Field Effect Transistor) using silicon carbide is used.

  The freewheel diode 5 is a semiconductor element for protecting the switching element 4 and is connected in parallel between the source terminal and the drain terminal of the switching element 4. Gate drive signal GS2 from inverter control circuit 129 is input to the gate terminal of switching element 4.

  The transformer coupling circuit 124 includes three transformers 6, an open-star connection for connecting the primary coil of the transformer 6, the AC input from the low-band inverter 122 and the output terminal 126 to each other, And a delta connection unit that connects the band inverter 123 to each other. The AC input from the low-band inverter 122 is a three-phase three-wire AC voltage, and the effective value is, for example, 420V.

  The configurations of the open star connection and the delta connection are as follows. One end of the primary coil is connected to the first phase of the AC input, and the other end is connected to the first phase output terminal 126. The secondary coil of the transformer 6 has one end connected to the first phase of the high-bandwidth inverter 123. And the other end is connected to the second phase. One end of the primary coil is connected to the second phase of the AC input and the other end is connected to the output terminal 126 of the second phase. And the other end is connected to the third phase. The secondary coil of the transformer 6 having one end of the primary coil connected to the third phase of the AC input and the other end connected to the output terminal 126 of the third phase has one end connected to the third phase of the high-bandwidth inverter 123. And the other end is connected to the first phase.

  A capacitor 130 is connected to the transformer coupling circuit 124 in parallel with the primary coil. The capacitor 130 is a capacitive element for forming a carrier removal filter of the high-band inverter 123 by using the capacitor 130 and the leakage inductance of the primary coil. This capacitor 130 is provided for each transformer 6 and is connected in parallel to the primary coil of the transformer 6.

  The switch 125 is connected in parallel to the primary coil of the transformer coupling circuit 124, and forms a bypass path to the transformer coupling circuit 124 in the closed state. This switch 125 is provided for each transformer 6 and is connected in parallel to the primary coil of the transformer 6.

  The bidirectional thyristor 135 is connected in parallel to the primary coil of the transformer coupling circuit 124, and forms a bypass path to the transformer coupling circuit 124 in a conductive state. This bidirectional thyristor 135 is provided for each transformer 6 and is connected in parallel to the primary coil of the transformer 6.

<Inverter control circuit 129>
FIG. 4 is a block diagram showing a configuration example of the inverter control circuit 129 of FIG. The inverter control circuit 129 includes an effective value command generation unit 21, an effective value calculation unit 22, an effective value voltage control unit 23, an instantaneous voltage waveform control unit 24, a phase matching circuit 25, an adder 26, a peak cut limiter 27, an instantaneous current It comprises a waveform control unit 28 and a gate drive signal generation unit 29.

  The effective value command generation unit 21 generates an effective value command for determining an effective value of the output voltage Vinv based on an instruction from the information processing terminal 11. The effective value calculation unit 22 obtains an effective value from the output voltage Vinv detected by the voltmeter 134. The effective value voltage control unit 23 is a control unit that performs feedback control so that the effective value of the output voltage Vinv is constant, and includes a subtractor 231 and a waveform command generation unit 232.

  The subtractor 231 generates an error of the effective value command by subtracting the effective value obtained by the effective value calculation unit 22 from the effective value command generated by the effective value command generation unit 21, and generates a waveform command generation unit 232. Output to The waveform command generation unit 232 generates a waveform command for determining the voltage waveform of the output voltage Vinv based on the test frequency command from the information processing terminal 11 and the error of the effective value command from the subtractor 231. The waveform command generator 232 includes, for example, an error amplifier and a sine wave generator, and generates a waveform command from the amplified error and the sine wave.

  The instantaneous voltage waveform control unit 24 is a control unit that performs feedback control of the instantaneous value of the output voltage Vinv, and includes an adder 241 and an inverter voltage PI control unit 242. The adder 241 adds the output voltage Vinv detected by the voltmeter 134 in reverse phase to the waveform command generated by the waveform command generator 232 to generate an error in the waveform command, and the inverter voltage PI controller 242 Output to Inverter voltage PI control unit 242 generates a waveform command for determining the current waveform of output current Iinv based on the error of the waveform command from adder 241. The PI control of the inverter voltage is a feedback control that controls the output as a linear function of the error between the waveform command and the detected value of the output voltage Vinv, and changes the output according to the integration of the error.

  The phase matching circuit 25 matches the waveform command of the inverter voltage PI control unit 242 by shifting the phase of the load current Iout detected by the ammeter 131 by a certain amount. The phase matching circuit 25 is a phase shifter that matches the detected value of the load current Iout with the phase on the secondary coil side of the transformer coupling circuit 124, and delays the phase of the detected value by 30 °. The phase shift of 30 ° corresponds to the phase difference between the star connection on the primary coil side and the delta connection on the secondary coil side.

  The inverter control circuit 129 performs feedforward control of the high-bandwidth inverter 123 using the detection value after matching by the phase matching circuit 25 as a current command value. By adopting such a configuration, the current command value is generated from the detected value of the load current Iout in consideration of the phase shift between the primary coil side and the secondary coil side of the transformer coupling circuit 124. First, it is possible to prevent the phase of the output current generated in the primary coil from being shifted with respect to the load current Iout.

  The adder 26 adds the detected value of the load current Iout from the phase matching circuit 25 to the waveform command generated by the inverter voltage PI control unit 242 in the same phase as the current command value, and outputs the same to the peak cut limiter 27. . The peak cut limiter 27 is a peak cut circuit for preventing an overcurrent when a load is short-circuited, and limits a current command value from the adder 26 so that a peak does not exceed a certain level. By employing such a configuration, it is possible to prevent an overcurrent from being generated in the primary coil of the transformer coupling circuit 124 when a load is short-circuited or the like.

  The instantaneous current waveform control unit 28 is a control unit that performs feedback control of the instantaneous value of the output current Iinv, and includes the adders 281 and 283 and the inverter current PI control unit 282. Since the load current Iout is a current actually flowing through the load connected to the output terminal 126, the detected value of the load current Iout is added in the same phase as the waveform command of the output current Iinv, and the command value of the instantaneous current waveform is obtained. As a result, feedforward control for operating the high-bandwidth inverter 123 in the constant current operation state is performed.

  When switching from the power supply of the low band test frequency f1 to the power supply of the high band test frequency f2, the switch 125 is switched to the open state, whereby the bypass path of the transformer coupling circuit 124 is cut off. At this time, a voltage is applied to both ends of the primary coil of the transformer coupling circuit 124 by the feedforward control of the high-band inverter 123 so that the load current before the interruption is maintained. The power supply can be continuously switched to the test frequency f2.

  The adder 281 adds the output current Iinv detected by the ammeter 132 in reverse phase to the waveform command from the peak cut limiter 27 to generate a waveform command error, and outputs the error to the inverter current PI control unit 282. . Inverter current PI control unit 282 generates a waveform command value of output voltage Vinv based on the error of the waveform command from adder 281. Adder 283 adds the waveform command generated by waveform command generator 232 to the waveform command value generated by inverter current PI controller 282 in the same phase, and outputs the result to gate drive signal generator 29.

  By performing feedforward control based on the waveform command generated by the waveform command generation unit 232, responsiveness to a change in the voltage command value can be improved. For example, if an instruction to reduce the effective value of the output voltage Vinv from 360 V to 330 V is input from the information processing terminal 11 to the inverter control circuit 129, the effective value of the output voltage Vinv can be quickly reduced. On the other hand, the output accuracy of the high-bandwidth inverter 123 can be improved by the feedback control based on the output voltage Vinv and the output current Iinv.

  Gate drive signal generation section 29 generates gate drive signal GS2 based on the waveform command value from adder 283, and outputs it to high-band inverter 123. The gate drive signal generator 29 is composed of a PWM (pulse width modulation) drive circuit, and generates a pulse-shaped gate drive signal GS2. The gate drive signal generation unit 29 includes, for example, a signal oscillator that generates a triangular wave signal, and a comparator that compares a waveform command value with the triangular wave signal. The frequency of the triangular wave signal, that is, the carrier frequency is fs2 = 42 kHz.

  Similarly to inverter control circuit 129, inverter control circuit 128 also generates gate drive signal GS1 based on load current Iout detected by ammeter 131 and output voltage Vout detected by voltmeter 133.

  FIG. 5 is a diagram illustrating an operation example of the power generation unit 12 in FIG. 2, and illustrates how the gate drive signal GS2 is generated from the waveform command value 7 and the triangular wave signal 8. The waveform command value 7 is a command value when f2 = 2.4 kHz is specified as the highest-order (40th-order) high-band test frequency f2 when the basic frequency f0 is 60 Hz. The carrier frequency of the triangular wave signal 8 is 42 kHz.

  The gate drive signal GS2 is a rectangular wave whose voltage level is switched between high and low at the intersection of the sinusoidal waveform command value 7 and the triangular wave signal 8. Even with such a high-order high-band test frequency f2, since the carrier frequency is high, sufficient resolution can be obtained, and distortion of the harmonic waveform can be prevented.

<Information processing terminal 11>
FIG. 6 is a block diagram showing an example of a functional configuration in the information processing terminal 11 of FIG. The information processing terminal 11 includes an operation unit 110, a load current designation unit 111, a test frequency designation unit 112, a switch control unit 113, a failure detection unit 114, and a thyristor control unit 115.

  Operation unit 110 receives a user operation, generates an operation signal, and outputs the operation signal to load current designation unit 111 and test frequency designation unit 112. Load current specifying section 111 generates a load current instruction for specifying an effective value of load current Iout based on an operation signal from operation section 110, and outputs the instruction to inverter control circuit 128 of power generation unit 12.

  For example, in response to a load current instruction for reducing the effective value of the load current Iout, the low-band inverter 122 is feedback-controlled so as to reduce the effective value of the load current Iout. At that time, the output current corresponding to the load current Iout can be generated in the primary coil of the transformer coupling circuit 124 by the feedforward control of the high-bandwidth inverter 123 performed using the detected value of the load current Iout as the current command value.

  The test frequency designation unit 112 generates a test frequency instruction for designating the basic frequency f0, the low band test frequency f1, or the high band test frequency f2 based on the operation signal from the operation unit 110, and outputs the test signal to the inverter control circuit 128 or 129.

  The switch control unit 113 generates an open / close drive signal KH for switching the switch 125 between the open state and the closed state, and outputs the signal to the switch 125 of the power generation unit 12. When switching from the low-band test frequency f1 power supply to the high-band test frequency f2 power supply, the switch control unit 113 switches the switch 125 from the closed state to the open state, thereby providing a bypass path through the switch 125. Cut off.

  By switching the switch 125 in this way, a power supply composed of a composite wave in which the voltage waveform of the low-band test frequency f1 is superimposed on the fundamental wave, and a power supply in which the interference wave of the high-band test frequency f2 is superimposed on the fundamental wave Can be arbitrarily selected. Further, by using the switch 125 for switching between the power supply of the low band test frequency f1 and the power supply of the high band test frequency f2, the durability can be ensured as compared with the case where a semiconductor switching element such as a bidirectional thyristor is used. it can.

  When generating a power supply of the low-band test frequency f1, the inverter control circuit 128 causes the low-band inverter 122 to generate a composite wave, while the inverter control circuit 129 stops the high-band inverter 123. When generating a power supply having the high-band test frequency f2, the inverter control circuit 128 causes the low-band inverter 122 to generate a fundamental wave, and the inverter control circuit 129 causes the high-band inverter 123 to generate an interference wave.

  In addition, when changing from the power supply of the high-band test frequency f2 to the power supply of the fundamental wave, the inverter control circuit 129 stops the high-band inverter 123 after the switch 125 is switched from the open state to the closed state. By adopting such a configuration, when changing from the power supply of the high band test frequency f2 to the power supply of the fundamental wave, the switch 125 is switched from the open state to the closed state before the high band inverter 123 is stopped. Therefore, it is possible to prevent a large current flowing from the low-band inverter 122 to the load via the transformer coupling circuit 124 from applying an overvoltage to the high-band inverter 123 via the transformer coupling circuit 124.

  When changing the power supply of the low-band test frequency f1 to the power supply of the high-band test frequency f2, the switch control unit 113 switches the switch 125 from the closed state to the open state after the high-band inverter 123 starts operating. . Since the operation of the high-bandwidth inverter 123 is started before the switch 125 is switched to the open state, even when the bypass path passing through the switch 125 is cut off, the primary coil of the transformer coupling circuit 124 is not connected. An output current corresponding to the load current Iout can be generated.

  Failure detection section 114 detects a failure of high-bandwidth inverter 123 and outputs a detection signal to thyristor control section 115. The failure detection unit 114 detects a failure of the high-bandwidth inverter 123 based on, for example, the output current Iinv, the output voltage Iinv, or the temperature T of the high-bandwidth inverter 123. Specifically, a failure of the high-bandwidth inverter 123 is detected based on a sudden change in output current or output voltage or a rise in temperature.

  The thyristor control unit 115 generates a gate drive signal GK for switching the bidirectional thyristor 135 of the power generation unit 12 from the cut-off state to the conductive state based on the detection result of the failure detection unit 114, and outputs the gate drive signal GK to the bidirectional thyristor 135. I do.

  Inverter control circuit 129 stops high-bandwidth inverter 123 after bidirectional thyristor 135 is switched to the conductive state by detection of a failure. By adopting such a configuration, when a failure of the high-bandwidth inverter 123 is detected and the inverter is stopped, a large current flowing from the low-bandwidth inverter 122 to the load via the transformer coupling circuit 124 causes the transformer coupling. Overvoltage can be reliably prevented from being applied to the high-bandwidth inverter 123 via the circuit 124.

  Since the bidirectional thyristor 135 is a semiconductor switching element, its response speed is faster than that of a mechanically operated device such as the switch 125. Therefore, it is possible to reliably prevent an overvoltage from being applied to the high-bandwidth inverter 123 due to an operation delay of the switching element.

  The switch control unit 113 switches the switch 125 from the open state to the closed state based on the detection result of the failure detection unit 114. After the switch 125 is switched to the closed state, the thyristor control unit 115 switches the bidirectional thyristor 135 from the conducting state to the blocking state. By employing such a configuration, the use of the bidirectional thyristor 135 is limited to a short time, so that the current withstand capability of the bidirectional thyristor 135 can be suppressed.

  Steps S101 to S103 in FIG. 7 are flowcharts illustrating an operation example at the start of the high band test in the information processing terminal 11 in FIG. The figure shows a processing procedure for starting a tolerance test using the high-band test frequency f2 after the end of the tolerance test using the low-band test frequency f1. First, the information processing terminal 11 instructs the inverter control circuit 128 of the power generation unit 12 of the basic frequency f0, and instructs the inverter control circuit 129 of the high-band test frequency f2 (step S101).

  Next, the information processing terminal 11 instructs the inverter control circuit 129 to start the operation of the high-bandwidth inverter 123 (Step S102). Next, after the high-bandwidth inverter 123 starts operating, the information processing terminal 11 switches the switch 125 of the power generation unit 12 from the closed state to the open state, thereby cutting off the bypass path passing through the switch 125 ( Step S103), this process ends.

  Steps S201 to S203 in FIG. 8 are flowcharts illustrating an operation example at the end of the high band test in the information processing terminal 11 in FIG. The figure shows a processing procedure when the AC output of the power generation unit 12 is returned to the fundamental wave after the end of the tolerance test using the high band test frequency f2.

  First, the information processing terminal 11 switches the switch 125 of the power generation unit 12 from the open state to the closed state (Step S201). Next, the information processing terminal 11 makes the bypass path passing through the switch 125 conductive by switching to the closed state, and then instructs the inverter control circuit 129 of the power generation unit 12 to stop the high-bandwidth inverter 123. (Step S202). When the operation of the high-bandwidth inverter 123 stops, the AC output of the power generation unit 12 returns to only the fundamental wave component (step S203).

  Steps S301 to S304 in FIG. 9 are flowcharts illustrating an operation example when a failure is detected in the information processing terminal 11 in FIG. The figure shows a processing procedure when a failure of the high-bandwidth inverter 123 is detected. First, the information processing terminal 11 switches the bidirectional thyristor 135 of the power generation unit 12 from the cutoff state to the conduction state (step S301).

  Next, the information processing terminal 11 instructs the inverter control circuit 129 to stop the high-bandwidth inverter 123 (Step S302). Next, after switching the switch 125 from the open state to the closed state (step S303), the information processing terminal 11 switches the bidirectional thyristor 135 from the conductive state to the cutoff state (step S304), and ends this processing.

  According to the present embodiment, since power amplification is performed by the switching operation of low-band inverter 122 and high-band inverter 123, it is easy to increase the capacity. In addition, since the high-order interference wave is generated by the high-band inverter 123 operating at the switching frequency fs2 higher than that of the low-band inverter 122, it is possible to prevent the high-order harmonic waveform from being distorted. Further, since the transformer coupling circuit 124 superimposes a higher-order interfering wave on the fundamental wave, an increase in power loss due to the switching operation can be suppressed as compared with a case where power amplification is performed by one inverter.

  Further, since high-band inverter 123 is controlled based on load current Iout output to PCS2, an output current corresponding to load current Iout can be generated in the primary coil of transformer coupling circuit 124.

  Further, according to the present embodiment, when a failure of high-bandwidth inverter 123 is detected, bidirectional thyristor 135 is switched from the cut-off state to the conductive state, thereby quickly forming a bypass path passing through bidirectional thyristor 135. be able to. Therefore, when the high-bandwidth inverter 123 fails, it is possible to prevent a large current flowing from the low-bandwidth inverter 122 to the load from applying an overvoltage to the high-bandwidth inverter 123 via the transformer coupling circuit 124.

  In the present embodiment, an example has been described in which high-band inverter 123 is formed of an FET using silicon carbide, but the present invention does not limit the configuration of high-band inverter 123 to this. For example, the high-bandwidth inverter 123 may be constituted by an FET or an IGBT.

  Further, in the present embodiment, an example in which the power generation unit 12 of the test power supply device 1 is configured by two inverter circuits has been described. However, in the present invention, the power generation unit 12 is configured by three or more inverter circuits. The present invention is also applicable to constituents. For example, the output may be increased by connecting two low-band inverters 122 in parallel.

  Further, in the present embodiment, an example has been described in which the threshold frequency fts1 and the threshold frequency fts2 are matched with each other so that the low band test frequency f1 and the high band test frequency f2 do not overlap. However, the present invention may be configured so that the adjustment range of the low-band test frequency f1 and the adjustment range of the high-band test frequency f2 overlap by setting the frequency exceeding the threshold frequency fts2 as the threshold frequency fts1.

DESCRIPTION OF SYMBOLS 1 Test power supply device 11 Information processing terminal 110 Operation part 111 Load current specification part 112 Test frequency specification part 113 Switch control part 114 Failure detection part 115 Thyristor control part 12 Power generation unit 121 Converter 122 Low band inverter 123 High band inverter 124 Transformer coupling circuit 125 Switch 126 Output terminal 127 Converter control circuit 128, 129 Inverter control circuit 130 Capacitor 131, 132 Ammeter 133, 134 Voltmeter 135 Bidirectional thyristor 21 Effective value command generator 22 Effective value calculator 23 Effective value voltage Control unit 231 Subtractor 232 Waveform command generation unit 24 Instantaneous voltage waveform control unit 241 Adder 242 Inverter voltage PI control unit 25 Phase matching circuit 26 Adder 27 Peak cut limiter 28 Instantaneous current waveform control units 281 and 283 Adder 282 inverter current PI control unit 29 gate drive signal generator 2 PCS
3 Commercial power supply 4 Switching element 5 Reflux diode 6 Transformer 7 Waveform command value 8 Triangular wave signal

Claims (6)

For a test target device to which AC power of a fundamental frequency is supplied, in a test power supply device for performing a tolerance test of voltage waveform distortion ,
A low-band inverter for generating a fundamental wave composed of the voltage waveform of the fundamental frequency,
A high-band inverter that generates an interference wave composed of a voltage waveform of a high-band test frequency higher than the fundamental frequency,
The low band inverter and the high band inverter is connected to the primary coil and the secondary coil, by overlapping the interfering wave to the fundamental wave, a transformer-coupled circuit that generates a voltage waveform supplied to the inspected device ,
A bidirectional thyristor connected in parallel to the primary coil of the transformer coupling circuit and forming a bypass path in a conductive state;
Failure detection means for detecting a failure of the high-bandwidth inverter;
A test power supply device comprising: a thyristor control unit that switches the bidirectional thyristor from the cutoff state to the conduction state based on the detection result of the failure detection unit. A switch connected in parallel to the primary coil of the transformer coupling circuit and forming a bypass path in a closed state;
Switch control means for switching the switch between an open state and a closed state,
The low-band inverter generates either the fundamental wave or a synthesized wave in which a voltage waveform of a low-band test frequency is superimposed on the fundamental wave,
When changing the power supply of the low-band test frequency to the power supply of the high-band test frequency, the switch is switched from a closed state to an open state to cut off the bypass path and generate the low-band inverter. The test power supply device according to claim 1, wherein a voltage waveform is switched from the composite wave to the fundamental wave . The switch control means switches the switch from an open state to a closed state based on a detection result of the failure detection means,
The test power supply device according to claim 2 , wherein the thyristor control means switches the bidirectional thyristor from the conductive state to the cutoff state after the switch is switched to the closed state. 4. The test power supply device according to claim 2, further comprising inverter control means for stopping the high-bandwidth inverter after the bidirectional thyristor is switched to the conductive state by detection of a failure. The inverter control means, when generating the power supply of the low-band test frequency, causes the low-band inverter to generate the composite wave, stops the high-band inverter, and generates the power supply of the high-band test frequency. In this case, the low-band inverter generates the fundamental wave, and the high-band inverter generates the interference wave, and further, when changing from the power supply of the high-band test frequency to the power supply of the fundamental wave, The test power supply device according to claim 4 , wherein the high-band inverter is stopped after the switch is switched from the open state to the closed state.   The test power supply according to any one of claims 1 to 5, wherein the failure detecting means detects a failure of the high-band inverter based on an output current, an output voltage, or a temperature of the high-band inverter. apparatus.

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