JP2018050395A - Inverter apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inverter apparatus capable of notifying a user of safety time even when the user performs operation in a state of contacting with wiring, a terminal board or the like.SOLUTION: According to one embodiment of this invention, an inverter apparatus includes: a power supply rectification circuit for rectifying AC power supply and outputting the rectified AC power supply between main power supply lines; a main circuit capacitor for smoothing the rectified output of the power supply rectification circuit; an inverter main circuit for inputting the output of the main circuit capacitor as power supply input; an operation unit for measuring voltage between terminals of the main circuit capacitor after power shutdown and calculating time required up to arrival of the measured inter-terminal voltage at a previously set predetermined voltage in accordance with a previously determined discharge time constant or a plurality of voltage values measured after the power shutdown; and a display unit for displaying the time calculated by the operation unit.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to an inverter device.

  The inverter device rectifies and smoothes an AC power supply to generate a DC voltage, and supplies the DC voltage to the inverter main circuit to drive the inverter main circuit. Here, a large capacity capacitor such as an aluminum electrolytic capacitor is used as a main circuit capacitor for smoothing the DC voltage. The DC power remains in the main circuit capacitor even after the power is turned off. For this reason, there is a risk of an electric shock if it comes into contact with the inverter device with DC power stored in the main circuit capacitor. In order to discharge the stored charge of the main circuit capacitor, a method of connecting a discharging resistor in parallel with the main circuit capacitor to shorten the discharge time when the power is shut off is generally used. In general, from the viewpoint of safety, in order for a user to work while touching a wiring or a terminal block, it is necessary to wait for a discharge process of charges accumulated in the main circuit capacitor after the power is shut off.

  However, since the capacitance value of the main circuit capacitor varies depending on the inverter capacitance, the discharge time is not uniformly determined. Therefore, for safety, it is recommended that the user set a discharge time corresponding to the inverter capacity having the longest discharge time, and wait for this discharge time. For this reason, even if the user uses an inverter device having an inverter capacity that discharges in a relatively short time, the user must wait for a certain period of time in order to work in contact with the wiring or the terminal block. The related art of the present application is disclosed in Patent Documents 1 and 2. For example, according to the technique described in Patent Document 1, the life expectancy of a smoothing electrolytic capacitor can be displayed.

JP 2007-288955 A JP 7-163045 A

  Provided is an inverter device capable of notifying a user of a time when there is no problem in safety even when working with contact with wiring or a terminal block.

  One embodiment includes a power supply rectifier circuit that rectifies an AC power supply and outputs the power between main power supply lines, a main circuit capacitor that smoothes the rectified output of the power supply rectifier circuit, and an inverter main circuit that inputs the output of the main circuit capacitor as a power supply. Measure the voltage between the terminals of the main circuit capacitor after the power is shut off, and according to a predetermined discharge time constant or a discharge time constant calculated based on a plurality of voltage values measured after the power is shut off And a calculation unit that calculates a time until the measured inter-terminal voltage reaches a predetermined voltage that is set in advance, and a display unit that displays the time calculated by the calculation unit.

Electrical configuration diagram of an inverter device schematically showing the first embodiment Flow chart schematically showing the process The figure which shows the change of the voltage between the terminals of the main circuit capacitor Display example Flowchart schematically showing processing in the second embodiment Display example The flowchart which shows the process in 3rd Embodiment roughly Display mode example (1) Display mode example (2) Flowchart schematically showing processing in the fourth embodiment The figure which shows the change of the voltage between the terminals of the main circuit capacitor Display mode example (1) Display mode example (2) Display mode example (3) Display mode example (4) The flowchart which shows the process in 5th Embodiment roughly Display example Flowchart schematically showing processing in the sixth embodiment Display example

Hereinafter, some embodiments of the inverter device will be described with reference to the drawings.
(First embodiment)
A first embodiment will be described with reference to FIGS. As shown in FIG. 1, the inverter device 1 includes terminals R, S, T for inputting, for example, a three-phase AC power supply 2 through a switch 3, and a power supply rectifier circuit 4 is connected to the terminals R, S, T. .

  The power source rectifier circuit 4 inputs and rectifies the AC power of the three-phase AC power source 2 input to the terminals R, S, and T. The output of power supply rectifier circuit 4 is applied to main power supply lines N1 and N2. A main circuit capacitor C is connected between the main power supply lines N1 and N2. The main circuit capacitor C smoothes the rectified output of the power supply rectifier circuit 4 and outputs DC power (DC voltage). This DC power is supplied to the control circuit 5 and the display (corresponding to the display unit) 6 through a DCDC converter (not shown). The DC power smoothed by the main circuit capacitor C is given to the inverter main circuit 7. The inverter main circuit 7 is configured by connecting a transistor such as an IGBT in a three-phase bridge, and converts the input DC power based on a PWM control signal output from the control circuit 5 to supply three-phase AC power to the motor 8. To do.

A discharge resistor RL serving as a discharge circuit is connected between the main power supply lines N1 and N2. The discharge resistor RL is provided so as to discharge the accumulated charge of the main circuit capacitor C.
The control circuit 5 includes an A / D converter 9, a calculation unit 10, and a volatile and nonvolatile memory 11. The A / D converter 9 receives the inter-terminal voltage Vdc between the main power supply lines N1 and N2, performs A / D conversion processing, and outputs the result to the arithmetic unit 10. The calculation unit 10 calculates the processing result of the A / D converter 9 based on a program stored in advance in the memory 11 while referring to the contents stored in the memory 11 as necessary. Thereby, the calculating part 10 can measure the voltage Vdc between terminals. The control circuit 5 can display the processing result on the display 6. The display 6 is a display unit such as a 7-segment LED or a liquid crystal display (LCD), for example, and can display information over one line or a plurality of lines.

  Terminals R, S, and T are mounted on the terminal block, and the user connects the wiring to the terminals R, S, and T of the inverter device 1 via the switch 3 to the three-phase AC power source 2 and the motor 8 by wiring. By connecting to the terminals U, V, W, the inverter device 1 can be operated.

The operation of the above configuration will be described. FIG. 2 is a flowchart schematically showing the processing contents, and FIG. 3 shows a temporal change in the voltage across the terminals of the main circuit capacitor.
When the user operates the switch 3 to turn on the power source, for example, a three-phase AC power source having an AC effective value of 400 V is input to the inverter device 1 from the three-phase AC power source 2. The power supply rectifier circuit 4 rectifies and outputs between the main power supply lines N1 and N2, and the main circuit capacitor C smoothes the rectified output and outputs DC power to the inverter main circuit 7. The control circuit 5 outputs the PWM control signal to drive the inverter main circuit 7 and rotate the motor 8. In this state, the inter-terminal voltage Vdc of the main circuit capacitor C between the main power supply lines N1 and N2 is maintained at a high normal operating voltage (for example, 550 to 600 V).

  The A / D converter 9 of the control circuit 5 reads the inter-terminal voltage Vdc of the main circuit capacitor C during normal operation, and the arithmetic unit 10 supplies a power supply set in advance so that the inter-terminal voltage Vdc is lower than the normal operating voltage. It is determined whether or not the cut-off determination voltage Va (for example, 520 V) or less. Thereby, it can be determined whether or not a power-off instruction has been given by the user operating the switch 3. That is, as shown in FIG. 3, after the switch 3 is turned off by the user at time T0, the power-off instruction is given at time Ta when the inter-terminal voltage Vdc is equal to or lower than the predetermined power-off determination voltage Va. Can be judged.

  Even after the power is shut off, the power supply voltage based on the voltage Vdc between the terminals of the main circuit capacitor C is supplied to the control circuit 5 and the display device 6. In this case, the control circuit 5 and the display device 6 normally operate. For this reason, as shown in FIG. 2, even after the power shutoff determination time Ta, the arithmetic unit 10 reads the inter-terminal voltage Vdc of the main circuit capacitor C as the voltage Va1 using the A / D converter 9. (S1 in FIG. 2). After the determination time Ta, the calculation unit 10 calculates the estimated waiting time Tth according to the voltage Va1 (S2 in FIG. 2). The computing unit 10 may calculate the estimated waiting time Tth according to the following equation (1).

Tth = τ · {ln (Va1 / Vth)} (1)
Here, τ represents a discharge time constant and is stored in advance in the nonvolatile memory 11. The value of τ is determined according to the standard value of the impedance of the discharge resistor RL and the standard power consumption of the load circuit such as the DCDC converter, the control circuit 5 and the display 6 described above. 1 is a value determined in advance at the time of design or manufacturing inspection.

  The predetermined voltage Vth is a preset voltage, and is set to 50 V or 60 V, for example. The predetermined voltage Vth is set to a value that is considered to be safe even if the user works by touching the wiring or the terminal block. When the calculation unit 10 calculates the estimated waiting time Tth, the display 6 displays the calculated estimated waiting time Tth (S3 in FIG. 2).

  For example, when the predetermined voltage Vth is set to 60V, the operation is as follows. As shown in FIG. 3, when the switch 3 is turned off at time T0 (= 50 sec), the power is shut off, and then the voltage Va1 (= 510 V) is measured at time Ta (= 60 sec). Using the discharge time constant τ (= 100 sec) stored in the memory 11, the estimated waiting time Tth (= 214 sec) is calculated by the equation (1), and the indicator 6 is displayed at the time Ta (= 60 sec). The estimated waiting time is 214 sec. FIG. 4 shows an example of this display mode. Thus, the user can clearly understand that it is sufficient to wait for 214 seconds at the time Ta (= 60 seconds).

  According to the present embodiment, the calculation unit 10 calculates the time until the measured inter-terminal voltage Vdc reaches a preset predetermined voltage Vth according to a predetermined discharge time constant τ, and the display 6 Now displays this calculated time. As a result, it is possible to inform the user of a time when there is no safety problem even if the work is performed in contact with the wiring or the terminal block. As a result, the worker's useless waiting time can be shortened.

(Second Embodiment)
5 and 6 show additional explanatory views of the second embodiment. As shown in FIG. 5, the processes in steps S1 to S3 may be repeated. After the display 6 displays the estimated waiting time Tth in steps S1 to S3 in FIG. 5, the calculation unit 10 starts measurement by the timer built in step S4 in FIG. 5, and the measurement time by this timer reaches a predetermined time. It may be determined whether or not (S5 in FIG. 5), and the processing in steps S1 to S3 in FIG. 5 may be repeated on condition that a predetermined time (for example, 10 sec) has elapsed. Then, as shown in FIG. 6, the display device 6 can repeatedly display and update the estimated waiting time Tth.

  When the measured voltage Va1 drops to a voltage equal to or lower than a predetermined voltage Vth (for example, 60 V) that can be treated by the user, the display 6 updates and displays 0 sec as the estimated waiting time Tth. The display unit 6 is not naturally supplied with power, whereby the control circuit 5 and the display unit 6 stop operating, and the display unit 6 turns off the display screen. The display 6 may be turned off before displaying 0 sec.

(Third embodiment)
7 to 9 show additional explanatory views of the third embodiment. After the processes of steps S1 and S2 in FIG. 7 are sequentially performed, the display 6 may alternately display the estimated waiting time Tth and the terminal voltage Vdc. Then, as shown in FIG. 8, the display 6 can notify the user of both information by alternately displaying the estimated waiting time Tth and the terminal voltage Vdc, that is, the measured voltage Va1. Also, as shown in steps S4 and S5 in FIG. 7, it may be determined whether a predetermined time has elapsed using a timer, and the processes in steps S1 to S3a in FIG. 7 may be repeated. Then, as shown in FIG. 8, the display unit 6 can alternately display and update the estimated waiting time Tth (for example, 10 min) and the inter-terminal voltage Vdc (measured voltage Va1: for example, 150 V), for example, every 3 seconds. it can.

  Although the display 6 has shown the form of alternately displaying the information of the estimated waiting time Tth and the inter-terminal voltage Vdc, the information selected according to the parameters set in advance by the user may be displayed. Further, when the display 6 uses, for example, an LCD capable of displaying two rows, as shown in FIG. 9, the estimated waiting time Tth until discharge and the current value of the inter-terminal voltage Vdc are simultaneously displayed. Anyway. In this case, the display 6 displays the estimated waiting time Tth as “until discharge: 10 min” and the inter-terminal voltage Vdc as “DC voltage: 150 V”, so that the user can be easily informed. .

(Fourth embodiment)
10 to 15 show additional explanatory views of the fourth embodiment. The A / D converter 9 of the control circuit 5 reads the inter-terminal voltage Vdc of the main circuit capacitor C during normal operation, and the arithmetic unit 10 supplies a power supply set in advance so that the inter-terminal voltage Vdc is lower than the normal operating voltage. It is determined whether or not the cut-off determination voltage Va (for example, 520 V) or less. Then, when the inter-terminal voltage Vdc becomes equal to or lower than the power cut-off determination voltage Va, it can be determined that the power is cut off.

  After the power-off cutoff determination timing, as shown in FIG. 10, the A / D converter 9 reads the inter-terminal voltage Vdc of the main circuit capacitor C as the voltage V1 at time T1 (S1a in FIG. 10). Thereafter, the A / D converter 9 reads the voltage Vdc between the terminals of the main circuit capacitor C as the voltage V2 at time T2 (S1b in FIG. 10). The reading time interval of the inter-terminal voltage Vdc is desirably about 10 sec or less, for example. Then, the calculation unit 10 calculates the discharge time constant τa according to the plurality of times T1 and T2 and the voltage values V1 and V2 measured corresponding to the plurality of times T1 and T2 (FIG. 10). S2a). At this time, the calculation unit 10 may calculate the discharge time constant τa according to the following equation (2).

τa = (T2−T1) / {ln (V1 / V2)} (2)
When the calculation unit 10 calculates the discharge time constant τa, it is desirable to sequentially store or sequentially update the calculated discharge time constant τa in the nonvolatile memory 11. Thereafter, the calculation unit 10 calculates an estimated waiting time Tth according to the calculated discharge time constant τa (S2b in FIG. 10). At this time, the arithmetic unit 10 may calculate the estimated waiting time Tth according to the following equation (3).

Tth = τa · {ln (V2 / Vth)} (3)
When the calculation unit 10 calculates the estimated waiting time Tth, the display 6 displays the calculated estimated waiting time Tth. Such a process is repeated every time the switch 3 is turned on / off by the user and the power is shut off. For this reason, the discharge time constant τa can be corrected and updated every time the power is shut off, and can be updated to a discharge time constant τa more suitable for practical use. As a result, even if the main circuit capacitor C deteriorates with time and its capacitance value changes with time, the discharge time constant τa can be set according to the capacitance value corresponding to this change with time.

  As shown in FIG. 11, when the power is shut down by turning off the switch 3 at time T0 (= 50 sec), the arithmetic unit 10 determines that the power is shut off at time T1 (= 60 sec) and determines the voltage V1 (= 480V), and then the voltage V2 (= 415V) is measured at time T2 (= 70 sec). Thereafter, the calculation unit 10 in step S2a determines the discharge time constant τa (= 68.7 sec) according to the equation (2). ) Is calculated. In step S2b, the estimated waiting time Tth (= 145 sec) can be calculated according to the equation (3), and the display 6 displays the estimated waiting time Tth. FIG. 12 shows an example of the display mode at this time. Thus, the user can clearly understand that it is only necessary to wait for “145 sec” from the time T2 (= 70 sec). Further, as shown in the second or third embodiment, the control circuit 5 uses the timer to calculate the estimated waiting time Tth every predetermined time, and the display 6 displays and updates the estimated waiting time Tth. Anyway.

(Modification 1 of 4th Embodiment)
As shown in FIG. 11, the period from time T0 to time T1 at which power-off is determined is Tx0, the period from time T1 to time T2 is Tx1, and the period from time T2 until the inter-terminal voltage Vdc reaches the voltage Vth. If Tx2, the estimated waiting time Tth is displayed or updated during the period Tx2. For this reason, the estimated waiting time Tth cannot be displayed during the periods Tx0 and Tx1, but during the period Tx1, the display unit 6 indicates that the power cut-off has been received in response to a command from the calculation unit 10. “OFF” may be displayed. FIG. 13 shows an example of this display change mode. That is, although the display 6 is not displayed at time T0, “OFF” is displayed at time T1, and the calculated estimated waiting time Tth is displayed at time T2. As a result, the user can be notified of information recognized by the control circuit 5 during internal processing and current information during discharge processing of the main circuit capacitor C.

(Modification 2 of 4th Embodiment)
Moreover, it can also deform | transform as follows by combining 2nd or 3rd Embodiment with 4th Embodiment. From time T1 to time T2 when the power-off is determined, the calculation unit 10 calculates the estimated waiting time Tth according to the equation (1) using the discharge time constant τ that is an initial value stored in the memory 11 in advance, and displays it. The device 6 may display the estimated waiting time Tth during the period Tx1 in response to a command from the calculation unit 10.

  FIG. 14 shows an example of the display mode at this time. That is, the display 6 displays no display at time T0, but displays an estimated waiting time Tth (= 154 sec) calculated using the discharge time constant τ at time T1. Thereafter, since the calculation unit 10 can newly calculate the discharge time constant τa at the time T2, the calculation unit 10 calculates the estimated waiting time Tth using the discharge time constant τa, and the display unit 6 displays the estimated waiting time Tth. Tth is displayed.

  That is, the memory 11 stores a predetermined discharge time constant τ in a nonvolatile manner, and the calculation unit 10 performs discharge based on the voltage values V1 and V2 measured corresponding to a plurality of times T1 and T2 after the power is turned off. When calculating the time constant τa, before calculating the discharge time constant τa, the time until the terminal voltage Vdc reaches a predetermined voltage is calculated using the discharge time constant τ stored in the memory 11; The display 6 displays this time. As a result, the information recognized by the control circuit 5 during the internal processing and the current information during the discharge processing of the main circuit capacitor C can be notified to the user, and useful information can be notified to the user.

  Further, such processing is repeated every time the switch 3 is turned on / off, but the calculation unit 10 sequentially stores or sequentially updates the discharge time constant τa in the nonvolatile memory 11 when the power is shut off. If so, the estimated waiting time Tth is calculated using the discharge time constant τa stored at the previous power-off, and the display 6 receives a command from the calculation unit 10 and waits for this estimation during the period Tx1. The time Tth can also be displayed.

  FIG. 15 shows an example of the display mode at this time. The display 6 displays nothing at time T0, but displays an estimated waiting time Tth (= 155 sec) calculated using the previously calculated discharge time constant τa at time T1. Thereafter, since the calculation unit 10 can newly calculate the discharge time constant τa at time T2, the calculation unit 10 calculates the estimated waiting time Tth using the discharge time constant τa calculated this time, and the display 6 This estimated waiting time Tth is displayed.

  According to the present embodiment, the memory 11 stores the discharge time constant τa calculated before or before in a non-volatile manner, and the calculation unit 10 is measured corresponding to a plurality of times T1 and T2 after power-off. When the discharge time constant τa is newly calculated based on the measured voltage values V1 and V2, the inter-terminal voltage Vdc is set to a predetermined value using the discharge time constant τa stored in the memory 11 before calculating the discharge time constant τa. The time required to reach the voltage Vth is calculated, and the display 6 displays this time. Thereby, useful information can be notified to the user.

(Fifth embodiment)
16 to 17 show additional explanatory views of the fifth embodiment. As shown in FIG. 16, similarly to the fourth embodiment, the arithmetic unit 10 uses the A / D converter 9 in S1a and S1b of FIG. 16 to convert the inter-terminal voltage Vdc at time T1 and T2 to the voltage V1. , V2, and the calculation unit 10 calculates the discharge time constant τa using these times T1, T2 and voltages V1, V2 in S2a of FIG. Here, when the calculated discharge time constant τa is equal to or greater than a predetermined discharge time constant threshold τL (S6: NO in FIG. 16), the calculation unit 10 determines that the sound is healthy, and the fourth embodiment Similarly, the estimated waiting time Tth is calculated in S2b of FIG. 16, and the estimated waiting time Tth is displayed in S3.

  However, the arithmetic unit 10 determines that there is an abnormality when the calculated discharge time constant τa becomes smaller than the threshold value τL (YES in S6 of FIG. 16). This threshold value τL is a value that is predetermined as an abnormal value, and is set to a value that is significantly smaller than the initial value τ of the discharge time constant. Therefore, the arithmetic unit 10 can immediately determine that an abnormality has occurred when the discharge time constant τa becomes smaller than the threshold value τL. In this case, the display 6 receives a command from the arithmetic unit 10 and displays that the main circuit capacitor C is abnormal (S7 in FIG. 16). FIG. 17 shows a display mode example at this time. As shown in FIG. 17, the display 6 can notify that the main circuit capacitor C is abnormal by displaying “CapEr”.

(Sixth embodiment)
18 and 19 show additional explanatory views of the sixth embodiment. In this embodiment, as shown in FIG. 18 and FIG. 19, a mode in which the estimated waiting time Tth, the terminal voltage Vdc, and the status of the main circuit capacitor C are displayed by combining the processing of the second or third embodiment. Show.

  As in the fifth embodiment, the arithmetic unit 10 determines whether the main circuit capacitor C is healthy or abnormal by comparing the discharge time constant τa with the threshold value τL in step S6. In the embodiment, when NO is determined in step S6, the fact that the status of the main circuit capacitor C is healthy is stored in the memory 11 (S8), and when YES is determined in step S6, the status of the main circuit capacitor C is changed. The fact that it is abnormal is stored in the memory 11 (S7a).

  Then, the calculation unit 10 calculates the estimated waiting time Tth in step S2b, and displays the inter-terminal voltage Vdc of the main circuit capacitor C on the display 6 as a DC voltage together with the estimated waiting time Tth in step S3a. The capacitor status “healthy” of the capacitor C is displayed on the display unit 6.

  FIG. 19 shows an example of a display mode during the process of step S3a of FIG. As shown in FIG. 19, the display 6 displays the time until discharge (for example, 10 min) and the terminal voltage Vdc as a DC voltage, and also displays the capacitor status.

  Then, as shown in steps S4 and S5 in FIG. 18, the calculation unit 10 determines whether or not a predetermined time has elapsed using a timer, and when the predetermined time has elapsed, determines YES in step S5, and in step S1c. The inter-terminal voltage Vdc is read as the voltage V2, and the process returns to step S2a. The calculation unit 10 calculates the discharge time constant τa again in step S2a, and determines whether or not the discharge time constant τa is smaller than the threshold value τL in step S6. This is to prevent the determination in step S6 from becoming unstable in the calculation process only once, and the determination can be made stably by repeating a plurality of times. The processes in steps S2a to S1c in FIG. 18 are repeated, and thus the process in step S3a is also repeated, and the estimated waiting time Tth, the voltage Vdc between terminals of the main circuit capacitor C, and the capacitor status are repeated. The display can be updated.

  Since the display 6 repeatedly displays and updates the time until discharge (for example, 10 min) and the inter-terminal voltage Vdc as a DC voltage, there is no safety problem even when working while touching the wiring or terminal block. Can be sequentially notified to the operator. Further, it is possible to notify the operator of the capacitor status sequentially.

  In addition, since the calculation unit 10 sequentially recalculates the discharge time constant τa during the discharge in step S2a, it can sequentially determine whether the capacitor status is healthy or abnormal by performing the determination process in step S6. This result can be displayed in step S3a. That is, as shown in FIG. 19, even when the capacitor status is healthy at the beginning of discharge, an abnormality may occur during discharge. In such a case, since the display 6 displays “capacitor status: abnormal”, it is possible to prompt the user to check the main circuit capacitor C.

  Such a process is repeated while the control circuit 5 and the display 6 are supplied with a voltage capable of normal operation. For this reason, the operator can be informed of the capacitor status during the discharge of the main circuit capacitor C.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and for example, the following modifications or expansions are possible.

  Although the embodiment in which the discharge time constant τa is calculated based on the voltages V1 and V2 at the two times T1 and T2 has been shown, the present invention is applied to a mode in which the discharge time constant τa is calculated based on a plurality of three or more voltages at three or more times. Also good.

A discharge time constant may be calculated based on a plurality of voltage values measured after power-off, and a time required to reach a predetermined voltage set in advance according to the discharge time constant may be calculated.
Several embodiments of the present invention have been described. However, the present invention is not limited to the configurations and conditions shown in the first to sixth embodiments, and these embodiments are presented as examples and the scope of the invention. It is not intended to limit. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  In the drawings, 1 is an inverter device, 2 is a three-phase AC power supply, 4 is a power supply rectifier circuit, 5 is a control circuit (calculation unit), 6 is a display (display unit), 7 is an inverter main circuit, 10 is a calculation unit, C is a main circuit capacitor, 11 is a memory (storage unit), N1 and N2 are main power lines, and τ and τa are discharge time constants.

Claims (6)

A power supply rectifier circuit that rectifies an AC power supply and outputs it between main power lines
A main circuit capacitor for smoothing the rectified output of the power rectifier circuit;
An inverter main circuit for inputting power to the output of the main circuit capacitor;
Measure the voltage between the terminals of the main circuit capacitor after the power is shut off, and according to a predetermined discharge time constant or a discharge time constant calculated based on a plurality of voltage values measured after the power is shut off A calculation unit for calculating a time until the measured inter-terminal voltage reaches a predetermined voltage set in advance;
A display unit for displaying the time calculated by the calculation unit;
An inverter device comprising: The arithmetic unit repeatedly measures the voltage between the terminals of the main circuit capacitor, and according to the discharge time constant, repeatedly calculates the time until the repeatedly measured voltage between the terminals reaches a predetermined voltage,
The inverter device according to claim 1, wherein the display unit repeatedly displays and updates the time calculated by the calculation unit.   The inverter device according to claim 1, wherein the display unit displays the voltage between the terminals of the main circuit capacitor and the time calculated by the calculation unit alternately or selectively. When the calculation unit calculates a discharge time constant based on a plurality of voltage values measured after power-off,
4. The display unit according to claim 1, wherein when the discharge time constant becomes smaller than a predetermined time constant set in advance, the display unit displays that the main circuit capacitor is abnormal. 5. Inverter device. A storage unit for storing a predetermined discharge time constant in a nonvolatile manner;
When the calculation unit calculates a discharge time constant based on a plurality of voltage values measured after power-off,
Before the discharge time constant is calculated, the calculation unit uses the discharge time constant stored in the storage unit to calculate the time until the terminal voltage reaches a predetermined voltage, and the display unit calculates the time. The inverter apparatus as described in any one of Claim 1 to 4 which displays. With a storage unit that stores the discharge time constant calculated before or before the previous power shutdown in a non-volatile manner,
When the calculation unit calculates a discharge time constant based on a plurality of voltage values measured after power-off,
Before the discharge time constant is calculated, the calculation unit uses the discharge time constant stored in the storage unit to calculate the time until the terminal voltage reaches a predetermined voltage, and the display unit calculates the time. The inverter apparatus as described in any one of Claim 1 to 4 which displays.

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