JP2017135938A - Inverter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inverter device capable of measuring capacity of a capacitor in a filter circuit, and that has means of facilitating exchange of the capacitor before performance of the filter circuit cannot be maintained.SOLUTION: An inverter device 1 comprises: a filter circuit F; a rectification circuit Rec1; a discharge resistive element R1; an initial charging circuit 2 that is configured by a series circuit of a diode D1 and a current restriction resistive element R2, and a short circuit switch SW2 connected in parallel to the series circuit 2; an inverter bridge circuit INV1 that is configured by a main circuit capacitor C8 connected between an other end of the initial charging circuit and an other of DC output terminals, and a semiconductor switching element; and a capacitor monitoring unit 4 that measures a terminal voltage of the discharge resistive element when an AC power supply P is cut off, calculates a capacity change or a capacity change rate of the capacitor in the filter circuit from a reference value by using the measurement result, and when a value of the capacity change or the capacity change rate becomes larger than a threshold, performs abnormality report processing.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to an inverter device having a filter circuit including one or more capacitors connected to an AC power source.

  In a filter circuit used for a power supply system of an inverter device, a generally used film capacitor has a lifetime, and the capacitance of the capacitor gradually decreases depending on the use environment. Therefore, the performance of the filter circuit deteriorates as the capacitance of the capacitor decreases. As the performance of the filter circuit deteriorates, noise flowing out from the inverter device side to the power supply line increases, which adversely affects peripheral devices connected to the same power supply system as the inverter device. Therefore, a means for prompting replacement of the capacitor is required before the performance of the filter circuit cannot be maintained.

Japanese Patent Laid-Open No. 8-196082

  In the past, there was no means to measure the capacitor capacity of the filter circuit built in the inverter device when it was incorporated in the system, so it was possible to detect even if the performance of the filter circuit deteriorated as the capacitor capacity decreased. There wasn't. Therefore, since it is necessary to suppress the capacity reduction as much as possible, it is necessary to select a capacitor having a very large capacity, which increases the size of the inverter device and further increases the cost of the filter circuit. It was.

  Therefore, an inverter device is provided that has means for prompting replacement of a capacitor before the capacitor capacity of the filter circuit can be measured even when incorporated in the system, and the performance of the filter circuit cannot be maintained.

  The inverter device of the embodiment is connected between a filter circuit including one or more capacitors connected to an AC power source, a rectifier circuit connected to the output side of the filter circuit, and a DC output terminal of the rectifier circuit. An initial charging circuit comprising a discharging resistance element, a series circuit of a diode and a current limiting resistance element, one end of which is connected to one of the DC output terminals, and a short-circuit switch connected in parallel to the series circuit; The inverter bridge circuit (inverter main circuit) composed of a main circuit capacitor and a semiconductor switching element connected between the other end of the initial charging circuit and the other of the DC output terminals and the AC power supply are cut off. Measured the terminal voltage of the discharging resistance element, and from the result, the capacitance change from the reference value of the capacitor of the filter circuit or the capacitance change rate Determined, and a capacitor monitoring unit that performs the capacitance change or capacitance when the rate of change of the value exceeds a threshold abnormality notification processing.

  In addition, the inverter device of the embodiment includes a filter circuit including one or more capacitors connected to an AC power supply, and a half connected to the output side of the filter circuit, one of the positive side and the negative side including a switching element. A first rectifier circuit configured by a bridge circuit, a second rectifier circuit configured to share the diode side of the first rectifier circuit and not supplying main circuit power to the DC bus, and a direct current of the second rectifier circuit A discharge resistance element connected between output terminals, an inverter bridge circuit composed of a main circuit capacitor and a semiconductor switching element connected between the DC buses, and the discharge power source when the AC power supply is cut off The terminal voltage of the resistance element is measured, and the capacitance change or capacitance change rate from the reference value of the capacitor of the filter circuit is obtained from the result, and the capacitance change or capacitance And a capacitor monitor the value of the rate makes the abnormality notification processing exceeds a threshold.

  In addition, the inverter device of the embodiment includes a filter circuit including one or more capacitors connected to an AC power supply, and a first circuit configured by a full bridge circuit including a switching element connected to the output side of the filter circuit. A rectifier circuit; a second rectifier circuit that is connected to the output side of the filter circuit and does not supply main circuit power to a DC bus; and a discharging resistance element connected between DC output terminals of the second rectifier circuit; An inverter bridge circuit composed of a main circuit capacitor and a semiconductor switching element connected between the DC buses, and a terminal voltage of the discharge resistance element when the AC power supply is cut off. Obtain the capacitance change or the capacitance change rate from the reference value of the circuit capacitor, and when the value of the capacitance change or the capacitance change rate exceeds a threshold value, an abnormality notification process is performed. And a capacitor monitoring unit that performs.

The figure which is 1st Embodiment and shows the electrical constitution of an inverter apparatus Flowchart showing the contents of processing by the capacitor monitoring unit The figure which shows an example of the voltage change of each part The figure which is 2nd Embodiment and shows the electrical constitution of an inverter apparatus The figure which is 3rd Embodiment and shows the electrical constitution of an inverter apparatus The figure which is 4th Embodiment and shows the electrical structure of the inverter system which consists of a some inverter apparatus The figure which shows an example of the voltage change of each part

(First embodiment)
Hereinafter, the first embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 shows an electrical configuration of the inverter device of the present embodiment. The power switch SW <b> 1 is connected between the three-phase AC power supply P and the filter circuit F built in the inverter device 1. The filter circuit F includes a three-phase common mode coil L1, capacitors C1, C2, and C3 that are star-connected to the input side of the coil L1, and capacitors C4, C5, and C6 that are star-connected to the output side of the coil L1. The capacitor C7 is connected between the neutral point of the star connection and the ground.

  Each phase output terminal of the filter circuit F is connected to the input terminal of the three-phase full-wave rectifier circuit Rec1, and the output terminal of the rectifier circuit Rec1 is connected to the DC bus + DC_1, -DC. A resistor R1 corresponding to a discharging resistive element is connected between the DC bus + DC_1 and -DC. The DC bus + DC_1 is connected to the DC bus + DC through a series circuit of a forward diode D1 and a resistor R2. Furthermore, the switch SW2 is connected in parallel to the series circuit. The diode D1, the resistor R2, and the switch SW2 constitute an initial charging circuit 2. The resistor R2 corresponds to a current limiting resistance element, and the switch SW2 corresponds to a short circuit switch.

  A main circuit capacitor C8, a C8 discharge resistor Rc and an inverter bridge circuit INV1 are connected between the DC buses + DC and -DC. The inverter bridge circuit INV1 is configured by connecting semiconductor switching elements such as IGBTs with a three-phase bridge. Each phase output terminal of the inverter bridge circuit INV1 is connected to one end of each phase winding (not shown) of the motor M. A voltage detector 3 is connected in parallel to the resistor R 1, and an output terminal of the voltage detector 3 is connected to an input terminal of the capacitor monitoring unit 4. The capacitor monitoring unit 4 controls ON / OFF of the switch SW2 and outputs an alarm to the outside as described later based on the monitoring results of the capacitors C1 to C6 constituting the filter circuit F.

  Next, the effect | action of this embodiment is demonstrated with reference to FIG.2 and FIG.3. FIG. 2 is a flowchart mainly showing the processing contents of the capacitor monitoring unit 4. In the initial state during normal operation of the inverter device 1, both the switches SW1 and SW2 are ON. When the switch SW1 is turned off from this state (S1), the main circuit capacitor C8 starts discharging (S2), and the voltage between the DC bus + DC and -DC decreases (S3).

  The capacitor monitoring unit 4 continues to turn on the switch SW2 of the initial charging circuit 2 until the voltage between the DC bus + DC and −DC reaches the set threshold voltage. During this time, the charge of the capacitor C8 is discharged by the discharge resistor Rc and an inverter control circuit (not shown), and partly by the resistor R1 via the switch SW2. When the voltage between the DC bus + DC and −DC is lower than the threshold voltage (S4; YES), the capacitor monitoring unit 4 turns off the switch SW2 (S5). Then, the discharge of the capacitor C8 is cut off by the diode D1, and the charges of the capacitors C1 to C6 of the filter circuit F are discharged by the resistor R1 through the rectifier circuit Rec1.

  Here, the time constant τf determined by the combined capacitance of the capacitors C1 to C6 and the resistor R1 of the filter circuit F and the time constant τc determined by the main circuit capacitor C8 and the resistor Rc are in a relationship of τf << τc, and the switch SW2 is Since the voltages of the capacitors C1 to C6 of the filter circuit F rapidly decrease after being turned off, the diode D1 is biased in the forward direction, and the main circuit capacitor C8 is not charged from the capacitors C1 to C6 of the filter circuit F.

At this time, the total capacity of the capacitors C1 to C6 in the filter circuit F can be measured by measuring the terminal voltage of the resistor R1. For example, R1 = 1 MΩ, voltage of resistor R1 at time T1 = V1 (S6), for example, time T2 (= T1 + 1s) (S7), voltage of resistor R1 at time T2 = V2 (S8). Then, the total capacity C _TTL can be obtained by equation (1) (S9).
C _TTL = 1 / {ln (V1) -ln (V2)} (1)

  FIG. 3 shows an example of a waveform in which the voltage changes in steps S1 to S8. (C) is the interphase input voltage of the filter circuit F, and the voltage is applied until 2 s when the switch SW1 is ON. When the switch SW1 is turned off, the voltages of the capacitors C1 to C6 appear in the interphase input voltage, and the interphase voltage hardly decreases due to the discharge of the capacitor C8 until the switch SW2 is turned off.

  When the switch SW2 is turned off as shown in (b), the charges of the capacitors C1 to C6 are discharged by the resistor R1 through the rectifier circuit Rec1 as shown in (d). The waveform A shown in (d) is set to C1 to C6 = 3.3 μF, and the waveform B is set to 3.3 μF × 0.8 = 2.64 μF on the assumption that the capacitance is reduced by 20%.

First, in the waveform A, when the terminal voltage V1 of the resistor R1 at time 4s is measured, and then the terminal voltage V2 at time 5s after 1 second is measured, V1 = 356V and V2 = 264V are obtained. Substituting these into equation (1) gives C _TTL = 3.3 μF. When the same calculation is performed for waveform B, C _TTL = 2.64 μF is obtained from V 1 = 318 V and V 2 = 218 V. That is, it can be detected that the capacity has decreased by 20% with _{respect to} the reference value C _TTL0 = _{3.3 μF} of the total capacity (S10; YES). In this case, the capacitor monitoring unit 4 performs alarm output and abnormality notification processing to the outside. The inverter device 1, the reference value C _TTL0 example, a setting mode which allows to set the fixed value or the measured values at the time of product shipment inspection, or the user sets the reference value C _TTL0 by the operation at the time of installation Have.

According to the present embodiment as described above, see change from baseline C _TTL0 total capacitance C _TTL of the capacitor C1 -C6, it can be Problem as an alarm time to change before the capacitor fails to outside.

(Second Embodiment)
Hereinafter, the same parts as those in the first embodiment are denoted by the same reference numerals, description thereof will be omitted, and different parts will be described. As shown in FIG. 4, in the inverter device 11 of the second embodiment, the rectifier circuit Rec1 is replaced with a rectifier circuit Rec2. The rectifier circuit Rec2 is a half-bridge rectifier circuit composed of a thyristor whose positive side of the diode bridge is a switching element. The initial charging circuit 2 is omitted in order to control the initial charging current of the main circuit capacitor C8 by controlling the firing timing of these thyristors.

  Further, the anodes of three diodes D2 (1 to 3) having cathodes connected in common are respectively connected to the phase output terminals of the coil L1, and between the cathode and the DC bus -DC. The resistor R3, which is a discharging resistance element, is connected. The diode D2 and the resistor R3 constitute a detection circuit 12. The rectifier circuit Rec2 corresponds to a first rectifier circuit, and the diode D2 in the detection circuit 12 corresponds to a second rectifier circuit. That is, in the detection circuit 12, the diode on the negative side of the rectifier circuit Rec2 and the diode D2 form a three-phase bridge to rectify the three-phase AC power supply. Illustration of the voltage detector 3 and the capacitor monitoring unit 4 is omitted.

Next, the operation of the second embodiment will be described. When the power supply P is cut off by the switch SW1, the thyristor of the rectifier circuit Rec2 is turned off. Therefore, even if the resistor R1 is connected to the output terminal of the rectifier circuit Rec2 as in the first embodiment, the capacitor C1 of the filter circuit F ~ C6 is not discharged. Thus, the detection circuit 12 is provided in the second embodiment. When the switch SW1 is turned off, the capacitors C1 to C6 are discharged through the path of the diode D2, the resistor R3, the negative side diode of the rectifier circuit Rec2. At this time, by measuring the voltage across the resistor R3, that is, the voltage between + DC_F and −DC, the total capacitance C _TTL can be measured in exactly the same procedure as in the first embodiment, and from the reference value C _TTL0 When the capacity change or rate of change is known and a preset threshold value is exceeded, an alarm can be output to the outside.

As described above, according to the second embodiment, even in the inverter device 11 including the half-bridge rectifier circuit, the change from the reference value C _TTL0 of the total capacitance C _TTL of the capacitors C1 to C6 is known, and before the capacitor breaks down The replacement time can be reported to the outside as an alarm. The detection circuit 12 can be realized by a limited circuit change such as adding only the discharge resistor R3, for example, by using a circuit provided for the purpose of controlling the thyristor of the rectifier circuit Rec2.

(Third embodiment)
As shown in FIG. 5, in the inverter device 21 of the third embodiment, the rectifier circuit Rec3 is composed of a full-bridge rectifier circuit in which all elements are thyristors, and the initial charging circuit 2 is the same as in the second embodiment. Is not prepared. Further, a detection circuit 22 is provided instead of the detection circuit 12 of the second embodiment. The detection circuit 22 includes a rectifier circuit Rec4 whose AC input terminal is connected to the output side of the coil L1, and a resistor R4 which is a discharge resistance element connected between the DC output terminals of the rectifier circuit Rec4. . The negative side of the output terminal of the rectifier circuit Rec4 is connected to the DC bus -DC. The rectifier circuits Rec3 and Rec4 correspond to first and second rectifier circuits, respectively.

Next, the operation of the third embodiment will be described. When the switch SW1 is turned off, the charge of the capacitors C1 to C6 of the filter circuit F is discharged by the resistor R4 via the rectifier circuit Rec4. Therefore, also in this case, the capacitor monitoring unit 4 can measure the total capacitance C _TTL as in the first embodiment by measuring the terminal voltage of the resistor R4, that is, the voltage between the terminal DC_F1 and the series circuit bus-DC, Capacitance changes of the capacitors C1 to C6 can be detected. It should be noted that the detection circuit 22 can be realized with limited circuit changes by using a circuit for the purpose of thyristor control of the rectifier circuit Rec3.

(Fourth embodiment)
6 and 7 show a fourth embodiment. In FIG. 6, two inverter devices 31 (1) and 31 (2) are connected in parallel to the power switch SW1. The inverter device 31 includes the switch SW3 between the terminal + DC_1 and the resistor R1 in the inverter device 1 of the first embodiment.

Next, the operation of the fourth embodiment will be described with reference to FIG. For example, when the switch SW1 of the inverter device 31 (1) is turned on and the switch SW1 is turned off with the switch SW3 of the inverter device 31 (2) turned off, the inverter devices 31 (1) and 31 (2) Charges of the capacitors C1 to C6 of the filter circuit F are discharged by the resistor R1 of the inverter device 31 (1). Therefore, by measuring the terminal voltage of the resistor R1 as in the first embodiment, the total capacitance C _TTL of the capacitors C1 to C6 of both the inverter devices 31 (1) and 31 (2) can be measured.

  FIG. 7 corresponds to FIG. The constant value of each element is the same as in the first embodiment. A waveform C in (d) is a case where the switches SW3 of both the inverter devices 31 (1) and 31 (2) are turned on, and a total capacity of 3.3 μF for two units is obtained using the equation (1). A waveform D is a case where the switch SW3 of the inverter device 31 (2) is turned off. Since the capacitors C1 to C6 of the inverter device 31 (2) are also discharged by the resistor R1 on the inverter device 31 (1) side, (1) The total capacity using the equation is a total capacity of 6.6 μF for two vehicles.

  In addition, when all the switches SW3 of each inverter device 31 are turned ON and the capacitance is measured by each device 31, the capacitances of the capacitors C1 to C6 of the filter circuit F vary. Cannot move and the capacity cannot be measured accurately.

As described above, according to the fourth embodiment, even when a plurality of inverter devices 31 are connected in parallel to the same power supply line, their total capacity C _TTL can be measured, and the reference value C _TTL0 The capacity change or rate of change from Therefore, when the value exceeds a preset threshold value, an alarm can be output to the outside. Note that ON / OFF of the switch SW3 may be switched by parameter setting or a manual switch. Further, a parameter for setting the alarm function to be valid / invalid can be provided, and this parameter can be linked to the switch SW3.

(Other embodiments)
The filter circuit may be configured to include one or more capacitors.
Since the value of the discharge resistor R1 affects the capacitance measurement accuracy, temperature correction may be performed as necessary.
The fourth embodiment may be applied to three or more inverter devices.
Although some embodiments of the present invention have been described, the present invention is not limited to the configurations shown in each embodiment, and these embodiments are presented as examples and are not intended to limit the scope of the invention. Not intended. 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 an initial charging circuit, 4 is a capacitor monitoring unit, 11 is an inverter device, 21 is an inverter device, 31 is an inverter device, P is a three-phase AC power supply, F is a filter circuit, and L1 is three Phase common mode coil, D2 is a diode, C1 to C6 are capacitors, Rec1 to Rec4 are rectifier circuits, R1 to R4 and Rc are resistors, C8 is a main circuit capacitor, INV1 is an inverter bridge circuit, and SW1 to SW3 are switches.

Claims (5)

A filter circuit including one or more capacitors connected to an AC power source;
A rectifier circuit connected to the output side of the filter circuit;
A discharging resistance element connected between the DC output terminals of the rectifier circuit;
An initial charging circuit comprising a series circuit of a diode and a current limiting resistance element, one end of which is connected to one of the DC output terminals, and a short-circuit switch connected in parallel to the series circuit;
An inverter bridge circuit composed of a main circuit capacitor and a semiconductor switching element connected between the other end of the initial charging circuit and the other of the DC output terminals;
When the AC power supply is shut off, the terminal voltage of the discharging resistance element is measured, and from the result, the capacitance change or the capacitance change rate from the reference value of the capacitor of the filter circuit is obtained, and the capacitance change or the capacitance change rate An inverter device comprising a capacitor monitoring unit that performs abnormality notification processing when the value of exceeds a threshold value. A filter circuit including one or more capacitors connected to an AC power source;
A first rectifier circuit which is connected to the output side of the filter circuit, and which is configured by a half bridge circuit in which one of the positive side and the negative side includes a switching element;
A second rectifier circuit configured to share the diode side of the first rectifier circuit and not to supply main circuit power to the DC bus;
A discharging resistive element connected between the DC output terminals of the second rectifier circuit;
An inverter bridge circuit composed of a main circuit capacitor and a semiconductor switching element connected between the DC buses;
When the AC power supply is shut off, the terminal voltage of the discharging resistance element is measured, and from the result, the capacitance change or the capacitance change rate from the reference value of the capacitor of the filter circuit is obtained, and the capacitance change or the capacitance change rate An inverter device comprising a capacitor monitoring unit that performs abnormality notification processing when the value of exceeds a threshold value. A filter circuit including one or more capacitors connected to an AC power source;
A first rectifier circuit connected to the output side of the filter circuit and configured by a full bridge circuit including a switching element;
A second rectifier circuit connected to the output side of the filter circuit and not supplying main circuit power to the DC bus;
A discharging resistive element connected between the DC output terminals of the second rectifier circuit;
An inverter bridge circuit composed of a main circuit capacitor and a semiconductor switching element connected between the DC buses;
When the AC power supply is shut off, the terminal voltage of the discharging resistance element is measured, and from the result, the capacitance change or the capacitance change rate from the reference value of the capacitor of the filter circuit is obtained, and the capacitance change or the capacitance change rate An inverter device comprising a capacitor monitoring unit that performs abnormality notification processing when the value of exceeds a threshold value.   The inverter apparatus as described in any one of Claim 1 to 3 which has a switch between the DC output terminal of the said rectifier circuit, and the said resistive element for discharge.   5. The inverter device according to claim 1, wherein the capacitor monitoring unit measures a terminal voltage of the discharging resistance element, and performs abnormality notification processing when a required capacitor capacity value falls below a threshold value. 6.

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