JP2003088144A - Inverter controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a discharge control operation only when an operation of an inverter is stopped and when a main power supply is cut off by an interruption. SOLUTION: In a discharge control circuit 25, when a contactor 12 is closed, a discharge transistor 27 is in an OFF-state by a closed a-contact relay 28. When the contactor 12 is opened, a b-contact relay 29 is closed, the discharge transistor 27 is in an ON-state, and charge accumulated in smoothing capacitors 17a and 17b is made to flow through a discharge resistor 26 and consumed so that a voltage between main circuit DC bus-bars can be lowered in a short time. When a main power supply is cut off by an interruption, etc., as the discharge transistor 27 can be put into an ON-state by a power supply backup circuit 30, the charge accumulated in the smoothing capacitors can be discharged in the same way, so that the voltage between the main circuit DC bus-bars can be lowered in a short time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter control device, and more particularly to an inverter control device having a discharge control function of electric charges accumulated in a smoothing capacitor.

[0002]

2. Description of the Related Art In many cases, an inverter device incorporates a smoothing capacitor for DC voltage of a main circuit. This smoothing capacitor has a large capacity and reaches several thousands to several hundreds of thousands of μF or more. Therefore, even if the power of the inverter device is turned off, the residual voltage due to the electric charge accumulated in the smoothing capacitor is still generated for a while. In such a state, it can be said that the work efficiency is low and the degree of danger is high during maintenance.

Therefore, conventionally, a method of providing a discharging circuit for a smoothing capacitor as described below has been adopted.

(1) A method in which a discharging resistor is connected in parallel with a smoothing capacitor to the DC circuit portion of the inverter main circuit.

(2) A method of connecting a relay such as a main circuit contactor auxiliary contact in series with the discharging resistor of (1) and discharging only when the inverter is stopped.

[0006]

However, the above measures have the following problems. In the method (1),
Since the discharge operation is always performed even when the inverter is operating, useless power consumption occurs. Further, it is necessary that the discharge resistance has a large capacity as compared with only when the inverter is stopped.

In the method (2), the relay uses a high voltage part (60
Since it may be used for 0V to 800V), it is necessary to connect a plurality of relays in series and examine the breaking capacity and life of the relays to prevent contact welding.

The present invention has been made in view of the above circumstances, and reliability can be improved by enabling discharge control operation only when the main power source is cut off due to an inverter operation stop or a power failure. It is an object to provide an inverter control device.

[0009]

In order to achieve the above object, an inverter control device according to the present invention is, in claim Utaka 1, a converter for converting an AC power source input via a contactor into a DC power source, and An inverter for converting the DC power supply output between the main circuit DC busbars by the converter into an AC power supply of an arbitrary frequency, a smoothing capacitor connected between the main circuit DC busbars for smoothing the DC power supply, and a terminal of the smoothing capacitor. A control device for controlling the converter and the inverter based on a voltage, an input state of the converter, an output state of the inverter, and the like, and a discharge circuit connected in parallel with the smoothing capacitor, the discharge transistor and the discharge transistor. A discharge circuit consisting of a discharge resistor connected to the current input side of Two contact relays having a secondary side commonly connected to their ends and performing an opening / closing operation in conjunction with an on / off operation of the contactor, wherein a first contact relay that closes when the contactor is on and when the contactor is off A second contact relay that is closed and one of the first contact relay
Transistor driving means for applying a power source for turning off the discharging transistor to the secondary side and power source for turning on the discharging transistor on the primary side of the second contact relay; A power supply backup circuit that is connected to the next side and that is charged by a power supply that turns on the discharge transistor and that includes a diode that blocks discharge from the backup capacitor to the power supply side during a power failure is provided. It has a feature.

According to this structure, in the discharge circuit, when the contactor is turned on, the discharging transistor is turned off by the closed first contact relay, but when the contactor is turned off, the second contact relay is turned on. Since the circuit is closed, the discharging transistor is turned on, and the charge accumulated in the smoothing capacitor flows through the discharging resistor and is consumed, so that the voltage between the main circuit DC buses can be reduced in a short time. Also, when the main power supply is cut off due to a power failure, the power supply backup circuit can turn on the discharge transistor.
Similarly, the charge accumulated in the smoothing capacitor can be discharged, and the voltage between the main circuit DC buses can be reduced in a short time. In this way, since the discharge control operation is performed only when the main power source is cut off due to the inverter operation stop and the power failure, it is possible to reduce wasteful power consumption. Further, since the two contact relays are for driving the discharge transistor, the contact life and reliability of the relay can be improved.

According to a second aspect of the present invention, there is provided a converter for converting an AC power supply connected via a contactor into a DC power supply, and an inverter for converting the DC power supply output between the main circuit DC busbars by the converter into an AC power supply of an arbitrary frequency. And a smoothing capacitor connected between the main circuit DC bus lines to smooth the DC power supply, and controlling the converter and the inverter based on the voltage across the terminals of the smoothing capacitor, the input state of the converter, the inverter output state, and the like. A control device, a discharge circuit connected in parallel with the smoothing capacitor, the discharge circuit including a discharging transistor and a discharging resistor connected to a current input side of the discharging transistor, and a terminal of the smoothing capacitor. ON operation of the discharge transistor until the voltage drops below a predetermined value And a backup capacitor that is charged by the DC power output from the converter and that supplies power to the transistor drive means during a power failure, and a diode that blocks discharge from the backup capacitor to the power supply side during a power failure. It is characterized by having a power supply backup circuit.

According to this structure, the transistor driving means monitors the voltage across the terminals of the smoothing capacitor, and when the voltage drops during the normal inverter control operation, it is determined that the contactor is turned off, and the voltage across the terminals of the smoothing capacitor is judged. The discharging transistor is turned on at least until the voltage drops below a predetermined value. As a result, the charge accumulated in the smoothing capacitor flows through the discharging resistor and is consumed, so that the voltage between the main circuit DC buses can be reduced in a short time.
Further, when the main power supply is cut off at the time of power failure, the transistor driving means can be supplied with power from the power supply backup circuit to turn on the discharge transistor, and thus the accumulated charge of the smoothing capacitor can be discharged similarly. The voltage between the main circuit DC buses can be reduced in a short time. In this way, the discharge control operation is performed only when the main power is cut off when the inverter operation is stopped or due to a power failure.
Useless power consumption can be reduced. At this time, in the transistor driving means, the above control can be realized by software processing, so that the discharge condition can be flexibly set and changed.

According to a third aspect of the present invention, in the above invention, the smoothing capacitor comprises a plurality of smoothing capacitors connected in series, and the discharging circuit is connected in parallel to each of the plurality of smoothing capacitors. It has a feature.

According to this structure, since the discharge circuit is provided in a one-to-one correspondence with each of the plurality of smoothing capacitors, it is possible to reduce the capacity and size of the discharge transistor or the regeneration transistor.

According to another aspect of the present invention, there is provided a converter for converting an AC power supply input via a contactor into a DC power supply, and an inverter for converting the DC power supply output between the main circuit DC busbars by the converter into an AC power supply of an arbitrary frequency. A smoothing capacitor for smoothing the DC power supply, wherein a plurality of smoothing capacitors connected in series between the main circuit DC busbars, a voltage between terminals of the plurality of smoothing capacitors, an input state of the converter, A control device for controlling the converter and the inverter based on an inverter output state, and a discharge circuit connected in parallel with each of the plurality of smoothing capacitors, the contacts closing in response to an off operation of the contactor. A plurality of discharge circuits each including a relay and a discharge resistor connected to the current input side of the contact relay It is characterized in that.

According to this structure, since the discharging circuit is provided in a one-to-one correspondence with each of the plurality of smoothing capacitors, the breaking capacity of the contact relay can be improved.
In addition, since the contact relay is used in the discharge circuit, it is possible to discharge the accumulated charge in the smoothing capacitor without a power backup even in the case of a power failure.

According to a fifth aspect of the present invention, in the above invention, the plurality of smoothing capacitors have balance resistors connected in parallel.

According to this structure, it is possible to apply a uniform voltage to the plurality of smoothing capacitors.

According to a sixth aspect of the present invention, in the above invention, a current detection resistor inserted on the current output side of the discharge transistor or the contact relay, and a detection circuit for detecting a voltage across the current detection resistor, It is characterized by further comprising a determination means for determining the presence or absence of a failure based on the presence or absence of the detection voltage of the detection circuit and the on / off operation of the contactor.

According to this structure, when a current flows to the current output side of the discharge transistor or the contact relay, the voltage generated by the current detection resistor is detected by the detection circuit and input to the determination means. Originally, the discharge transistor, the regeneration transistor, or the contact relay does not operate when the contactor is on, but operates when the contactor is off. Therefore, if the detection voltage is input from the detection circuit when the contactor is turned on, or if the detection voltage is not input from the detection circuit when the contactor is turned off, the determination means fails the discharge transistor or regeneration transistor or contact relay. It can be determined that there is. As a result, it becomes possible to notify the clerk of the occurrence of the failure by the alarm output.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> FIG. 1 is a block diagram showing the configuration of a first embodiment of an inverter control device according to the present invention.

In FIG. 1, a three-phase main power supply 11 is input via a contactor 12 to a converter 13 composed of an IGBT (insulated gate bipolar transistor) element or the like. The output of the converter 13 is input to the inverter 14 which is also composed of an IGBT element and the like via the main circuit DC buses P and N. Inverter 14
Is output to the AC motor 15. Two smoothing capacitors 17a and 17b arranged in series are connected between the main circuit DC buses P and N. Each smoothing capacitor 17a, 17b has a balance resistor 9a,
9b are connected in parallel. Balance resistors 9a, 9b
Is for evenly applying a voltage to the smoothing capacitors 17a and 17b, and has substantially the same resistance value.

In order to control the inverter device composed of the converter 13, the inverter 14 and the smoothing capacitors 17a, 17b, the voltage across the smoothing capacitors 17a, 17b, that is, the main circuit DC voltage between the main circuit DC buses P, N is set. A voltage detection circuit 18 for detecting is provided. In addition, a current sensor 1 for detecting a current is provided on each of the input side of the converter 13 and the output side of the inverter 14.
9 and 20 are provided, and a speed detector 21 that mechanically detects the rotation speed is attached to the rotating shaft of the AC motor 15.

The control circuit 22 includes a so-called microcomputer, and these voltage detection circuit 18, current sensor 19,
20 based on the outputs of the speed detector 21 and the speed detector 21, a control calculation process is performed by a microcomputer, and as a control signal of the inverter device,
The gate control signal G1 for the converter 13 and the gate control signal G2 for the inverter 14 are generated.

The gate drive circuit 23 performs insulation amplification of the gate control signal G1 input from the control circuit 22 and outputs the gate drive signal to the converter 13. The gate drive circuit 24 also performs insulation amplification of the gate control signal G2 input from the control circuit 22 and outputs the gate drive signal to the inverter 14. As a result, AC power of a desired frequency is supplied from the inverter 14 to the AC motor 15, and the AC motor 15 is drive-controlled to a desired state.

In such an inverter control device,
A discharge control circuit 25 is provided in the inverter device. The discharge control circuit 25 has a discharge circuit composed of a discharge resistor 26 and a discharge transistor 27 connected between the main circuit DC buses P and N, and a secondary side connected to a control end (gate) of the discharge transistor 27. A contact relay 28 and a b-contact relay 29, and a power supply backup circuit 30 provided on the primary side of the b-contact relay 29 are provided.

In the discharge circuit, one end of the discharge resistor 26 is connected to the main circuit DC bus P and the other end is the discharge transistor 2.
7 is connected to the current input terminal. The current output terminal of the discharging transistor 27 is connected to the main circuit DC bus N.

The power supply backup circuit 30 is composed of a diode 31 and an electric double layer capacitor (trade name "super capacitor": hereinafter referred to as "super capacitor") 32. The diode 31 has an anode connected to the + 15V power source of the gate drive circuit 23 and a cathode connected to the primary side of the b-contact relay 29. The supercapacitor 32 is connected between the primary side of the b-contact relay 29 and the main circuit DC bus N. The primary side of the a-contact relay 28 is connected to the −15V power source of the gate drive circuit 23. The gate drive circuit 23 constantly outputs a -15V power source and a + 15V power source.

A-contact relay 28 and b-contact relay 29
Is an auxiliary contact that opens and closes in conjunction with turning on and off of the contactor 12. That is, when the contactor 12 is on, the a-contact relay 28 is closed and the b-contact relay 2 is closed.
9 is open circuit. As a result, the −15V power supply from the gate drive circuit 23 is applied to the control end (gate) of the discharging transistor 27, and the discharging transistor 27 is turned off.

On the contrary, when the contactor 12 is off,
The a-contact relay 28 is opened and the b-contact relay 29 is closed. As a result, the + 15V power source from the gate drive circuit 23 is applied to the control terminal (gate) of the discharging transistor 27, and the discharging transistor 27 is turned on.

In the power supply backup circuit 30, the supercapacitor 32 is charged by receiving + 15V power supply from the gate drive circuit 23 via the diode 31. When the + 15V power supply is cut off from the gate drive circuit 23 due to a power failure or the like, the charging voltage of the supercapacitor 32 is applied to the gate of the discharging transistor 27. At this time, the diode 31 prevents unnecessary discharge to the gate drive circuit 23.

Next, the discharge control operation of the inverter control device configured as described above will be described. When the contactor 12 is turned on, that is, when the inverter device is in the control state, the -15V power source is input to the control end (gate) of the discharging transistor 27 from the closed a-contact relay 28. The discharge transistor 27 is turned off, and the discharge control circuit 25 is in a stopped state.

On the other hand, when the contactor 12 is not turned on, that is, when the inverter device is in the control stop state, the + 15V power source from the closed b-contact relay 29 is the control end (gate) of the discharging transistor 27. Is input to the discharge transistor 27, the discharge transistor 27 is turned on, and the discharge control circuit 25 enters the control state. In this control state, the electric charges accumulated in the smoothing capacitors 17a and 17b are released as heat energy through the discharge resistor 26, so that the voltage between the main circuit DC buses P and N can be reduced in a short time.

Further, even when the main power supply is cut off due to a power failure, the discharge transistor 27 can be turned on by the power supply backup circuit 30, so that the charge accumulated in the smoothing capacitors 17a and 17b can be rapidly reduced. Can be made.

According to the first embodiment, since the discharge control circuit 25 uses the discharge transistor 27 as the discharge control device, the reliability of the circuit is higher than that when the mechanical contact such as the relay is used. There is an advantage to improve. Further, since the discharge is performed only when the inverter control is stopped, useless power consumption can be reduced. Further, since the power source backup circuit is provided, even when the main power source is cut off due to a power failure, the smoothing capacitors 17a and 17b can be discharged similarly to the mechanical contacts such as relays. In addition, since the two contact relays are for driving the discharge transistor, the contact life and reliability of the relay can be improved.

<Second Embodiment> FIG. 2 is a block diagram showing the configuration of a second embodiment of the inverter control device according to the present invention. In FIG. 2, elements that are the same as the elements shown in FIG. 1 are given the same reference numerals. Here, the description will focus on the part according to the second embodiment.

As shown in FIG. 2, in the second embodiment,
A discharge circuit 35 provided in the inverter device is composed of a discharge resistor 26 and a discharge transistor 27 connected between the main circuit DC buses P and N. Along with this, the configuration of the gate drive circuit 23 is changed, a control circuit 34 is provided instead of the control circuit 22, and a power supply backup circuit 36 is further provided.

The control circuit 34 controls the voltage detection signal D of the voltage between the main circuit DC buses P and N detected by the voltage detection circuit 18.
1, the discharge control signal H1 is continuously output until the voltage between the main circuit DC buses P and N becomes zero. In addition, as a method of outputting the discharge control signal H1, a condition that a set voltage of the voltage between the main circuit DC buses P and N is provided and the discharge control signal H1 is output until a certain voltage or less is provided. , Contactor 1
Alternatively, the discharge control signal H1 may be output based on the open / closed state of No.2.

The gate drive circuit 23 is provided with a transistor drive circuit 33 for driving the discharge transistor 27. The transistor drive circuit 33 is configured, for example, as shown in FIG. 3, and the control circuit 34 outputs the discharge control signal H.
Control terminal (gate) of the discharging transistor 27 in response to 1
The discharge transistor drive signal H2 is output to the.

Further, the power supply backup circuit 36 includes a diode 37 and a supercapacitor 38, and the control circuit 3 relating to drive control of the discharge circuit 35 at the time of power failure or the like.
4. It is configured and arranged so as to supply power to the peripheral portion of the discharge circuit such as the voltage detection circuit 18. As described above, the diode 37 is for preventing wasteful discharge from the supercapacitor 38 to the power supply side at the time of power failure or the like. The transistor drive circuit 33 is also provided with a power supply backup circuit.

FIG. 3 is a block diagram showing the structure of the transistor drive circuit 33. In FIG. 3, the transistor drive circuit 33 includes an insulation amplifier circuit 41. The insulation amplifier circuit 41 insulation-amplifies the discharge control signal H1 input from the control circuit 34, and outputs the discharge transistor drive signal H2. The secondary power supply of the insulation amplifier circuit 41 is supplied from the power supply control circuit 42 via the transformer 43. Further, a supercapacitor 44 is connected to the secondary side of the transformer 43 so that discharge control can be performed even when the main power supply is cut off due to a power failure or the like.

Next, the discharge control operation of the inverter control device configured as described above will be described. The control circuit 34
Based on the voltage detection signal of the voltage detection circuit 18, the voltage state between the main circuit DC buses P and N is monitored, and when the voltage starts to drop, the discharge control signal H1 starts to be output. Or contactor 1
The closing state of No. 2 is monitored, and when the closed state changes to the open state, output of the discharge control signal H1 is started. As a result, the discharging transistor 27 is turned on, and the smoothing capacitors 17a,
The electric charge accumulated in 17b is started to be discharged as heat energy through the discharge resistor 26, and the voltage between the main circuit DC buses P and N is drastically dropped. The control circuit 34
Since the discharge control signal H1 is continuously output until the voltage value between the main circuit DC bus lines P and N becomes zero or until it becomes a constant voltage, the voltage between the main circuit DC bus lines P and N should be lowered in a short time. You can

When the main power supply is cut off due to a power failure, the control circuit 34 and the voltage detection circuit 18 are supplied with power from the power supply backup circuit 36 to maintain the normal operation state, and the transistor drive circuit 33 is also superposed. Capacitor 4
Similarly, the power supply backup is received by the unit 4 to maintain the normal operation state. Therefore, even if the main power supply is cut off, such as during a power failure, the discharge transistor 27 can be turned on, and similarly, the electric charges stored in the smoothing capacitors 17a and 17b can be rapidly reduced.

According to this second embodiment, the discharge circuit 3
In No. 5, since the discharge transistor 27 is used as the discharge control device, there is an advantage that the reliability of the circuit is improved as compared with the case where a mechanical contact such as a relay is used. Also,
Since the discharge control is performed by software processing in the control circuit 34, unnecessary power consumption can be reduced and the discharge condition can be flexibly changed. Further, since the power source backup circuit is provided, even when the main power source is cut off due to a power failure, the smoothing capacitors 17a and 17b can be discharged similarly to the mechanical contacts such as relays.

<Third Embodiment> FIG. 4 is a block diagram showing the configuration of a third embodiment of the inverter control device according to the present invention. Note that, in FIG. 4, elements that are the same as the constituent elements shown in FIG. 1 are assigned the same reference numerals. Here, the description will focus on the part according to the third embodiment.

As shown in FIG. 4, in the inverter device of the third embodiment, a rectifier 51 having a diode bridge structure is provided in place of the converter 13, and a regenerative circuit for performing resistance regeneration instead of power regeneration during regenerative operation. 52 is provided. The regenerative circuit 52 includes a main circuit DC bus P,
It is composed of a regenerative resistor 53 and a regenerative transistor 54 connected in series between N. Along with this, a gate drive circuit 55 that replaces the gate drive circuit 23 is provided.

The gate drive circuit 55 is provided with a transistor drive circuit 56 for driving the regeneration transistor 54. The transistor drive circuit 56 is configured, for example, as shown in FIG. 5, receives the main circuit DC voltage signal S1 which is the detection target voltage signal of the voltage detection circuit 18, and supplies the regeneration transistor to the control terminal (gate) of the regeneration transistor 54. The drive signal S2 is output.

FIG. 5 is a block diagram showing the structure of the transistor drive circuit 56. In FIG. 5, the main circuit DC voltage signal S1 is the regenerative control reference circuit 61 and the regenerative control circuit 6
Entered in 2. The regenerative control reference circuit 61 generates a regenerative reference signal S3 having a predetermined value from the main circuit DC voltage signal S1 and inputs it to the regenerative control circuit 62. Regenerative control circuit 62
Then, the regeneration transistor control signal S4 is output to the insulation amplifier circuit 41 until the main circuit DC voltage signal S1 becomes equal to or lower than the voltage value of the regeneration reference signal S3. The regeneration transistor control signal S4 is insulation-amplified by the insulation amplification circuit 41 and output to the primary side of the a-contact relay 63.

The secondary power source (+1 of this isolation amplifier circuit 41
5 V) is supplied from the power supply control circuit 42 via the transformer 43 and the rectifying / smoothing circuit 64. Further, the secondary power source (+ 15V) input end of the isolation amplifier circuit 41 is connected to the diode 6
5 is connected to the primary side of the b-contact relay 66, and the secondary side of the a-contact relay 66 is connected to the secondary side of the b-contact relay 63. In addition, the primary side of the a-contact relay 63 and b
A super capacitor 67 is connected between the contact relay 66 and the primary side.

The a-contact relay 63 and the b-contact relay 66 are
It is an auxiliary contact that opens and closes in conjunction with the on / off operation of the contactor 12. That is, when the contactor 12 is on (inverter control operation and regenerative operation), the a-contact relay 63 is closed and the b-contact relay 66 is open. As a result, the output of the insulation amplifier circuit 41 is output as the regeneration transistor control signal S2 via the a-contact relay 63.

On the contrary, when the contactor 12 is off (when the inverter control operation is stopped), the a-contact relay 63 is opened and the b-contact relay 66 is closed. As a result, the secondary power source (+15 V) of the insulation amplifier circuit 41 is connected to the b-contact relay 66.
Is output as a regeneration transistor control signal S2 via.

The supercapacitor 67 is charged by receiving + 15V power supply from the power supply control circuit 42 via the diode 65. When the + 15V power supply is cut off from the power supply control circuit 42 during a power failure or the like, the charging voltage of the supercapacitor 67 is output as the regeneration transistor control signal S2 via the b-contact relay 66. At this time, the diode 65 prevents useless discharge to the power supply control circuit 42.

Next, the discharge control operation of the inverter control device configured as described above will be described. In the regenerative operation performed during the inverter control operation, the transistor drive circuit 56 outputs the regenerative transistor control signal S2 only within a certain period until the main circuit DC voltage signal S1 falls below the voltage of the regenerative reference signal S3 having a predetermined value. Since it is output,
In the regenerative circuit 52, the regenerative transistor 54 performs an on operation only within a certain period of the regenerative operation, and the regenerative resistor 53 regenerates the resistance.

When the inverter control operation with the contactor 12 turned off is stopped, the transistor drive circuit 56
Since the 15V power supply is output as the regeneration transistor control signal S2, in the regeneration circuit 52, the regeneration transistor 54 performs an ON operation, the regeneration resistor 53 functions as a discharge resistor, and the main circuit DC bus P, N The voltage can be lowered. Further, even when the main power supply is cut off due to a power outage, the backup power supply (supercapacitor 67) provided in the transistor drive circuit 56 can turn on the regeneration transistor 54, so that the smoothing capacitors 17a and 17b are similarly stored. The generated charge can be reduced quickly.

According to the third embodiment, since the regenerative circuit can be used even when the inverter control operation is stopped, it can be used as a substitute for the discharge circuit. In the transistor drive circuit, the open / closed state of the contactor is used to determine whether the inverter control operation is in progress or the inverter control operation is stopped, but other signals may be used.

Further, since the power supply backup is provided on the circuit when the contactor is off, the regenerative transistor 54 can be driven even when the main power source is cut off due to a power failure or the like, and the regenerative resistor is used as a discharge resistor. Can be used. Therefore, the same operation as in the first and second embodiments
The effect is obtained. Further, since the two contact relays are for driving the regeneration transistor, the contact life and reliability of the relay can be improved.

<Fourth Embodiment> FIG. 6 is a block diagram showing the configuration of a fourth embodiment of an inverter control device according to the present invention. In the fourth embodiment, in the configuration shown in FIG. 2, in the configuration shown in FIG.
5, a discharge circuit 75 is provided. Discharge circuit 7
5, the series circuit of the discharging resistor 76 and the discharging transistor 77 is connected in parallel with the smoothing capacitor 17a, and the series circuit of the discharging resistor 78 and the discharging transistor 79 is connected in parallel with the smoothing capacitor 17b. The connection point between the smoothing capacitors 17a and 17b and the connection point between the discharging transistor 77 and the discharging resistor 78 are commonly connected. That is, the discharge circuit 75 is composed of two discharge circuits connected in series.

The discharge transistor drive signal H2 output from the transistor drive circuit 33 is applied to the control terminals (gates) of the two discharge transistors 77 and 79, respectively. Others are the same as the configuration shown in FIG.

The operation is the same as that of the second embodiment shown in FIGS. 2 and 3, and in addition to the same operational effect,
In the fourth embodiment, the voltage between the main circuit DC bus lines P and N is divided by half and applied to the discharge resistors 76 and 78 and the discharging transistors 77 and 79, so that these devices can be operated at low voltage. It can be made smaller in capacity and smaller, and can be mounted on a substrate depending on conditions.

Although the example of application to FIG. 2 (second embodiment) is shown, the same applies to the configurations of FIG. 1 (first embodiment) and FIG. 4 (third embodiment). You can

<Fifth Embodiment> FIG. 7 is a block diagram showing the configuration of a fifth embodiment of an inverter control device according to the present invention. In the fifth embodiment, a discharge circuit 81 is provided instead of the discharge circuit 75 in the configuration shown in FIG. In the discharge circuit 81, the series circuit of the discharge resistor 82 and the discharge b-contact relay 83 is a smoothing capacitor 17a.
, And a series circuit of a discharge resistor 84 and a discharge b-contact relay 85 is connected in parallel with the smoothing capacitor 17a. Smoothing capacitor 17a and smoothing capacitor 17
b connection point, discharge b contact relay 83 and discharge resistance 84
And the connection point of are commonly connected.

Accordingly, in the configuration shown in FIG.
A gate drive circuit 86 is provided in place of the gate drive circuit 23, and the control circuit 22 shown in FIG.
Is provided. Auxiliary contacts of the contactor 12 can be used for the discharging b-contact relays 83 and 84.
The discharging b-contact relays 83 and 84 are closed when the main power source is cut off, such as when the contactor 12 is off or when there is a power failure.
No power backup circuit is required. Therefore, the gate drive circuit 86 receives the gate control signal G from the control circuit 22.
Only the operation of receiving 1 and driving the converter 13 may be performed.

In the fifth embodiment, the discharge resistor 82,
Since the voltage between the main circuit DC busbars P and N is divided by 1/2 and applied to the 84 and discharging b-contact relays 83 and 85, the breaking capacity of the discharging contacts can be doubled. Is. In addition, since the contact relay is used in the discharge circuit, it is possible to discharge the accumulated charge in the smoothing capacitor without a power backup even in the case of a power failure.

<Sixth Embodiment> FIG. 8 is a block diagram showing the configuration of a sixth embodiment of the inverter control device according to the present invention. In the sixth embodiment, in the configuration shown in FIG. 1, the discharge current detection resistor 90 is provided between the current output side of the discharge transistor 27 and the main circuit DC bus N. Accordingly, the voltage detection circuit 92 is provided instead of the voltage detection circuit 18, and the control circuit 93 is provided instead of the control circuit 22.

The discharge current detecting resistor 91 is the discharge resistor 26.
It has a resistance value sufficiently smaller than that. Voltage detection circuit 9
2 detects the voltage between the main circuit DC buses P and N, and also detects the voltage across the discharge current detecting resistor 91,
The voltage detection signal D1 and the discharge current detection signal D2 are output to the control circuit 93. The control circuit 93 receives the voltage detection signal D1 and the discharge current detection signal D2 from the voltage detection circuit 92, and performs the inverter control operation based on the voltage detection signal D1 as described in the first embodiment, and the discharge current. A failure detection operation is performed based on the detection signal D2.

The failure detection operation based on the discharge current detection signal D2 will be described below. If the discharge current detection signal D2 is not detected when the contactor 12 is off, that is, when the + 15V power supply is applied to the control end (gate) of the discharge transistor 27, the discharge operation should be performed. The control circuit 93 can detect the off-mode failure of the discharging transistor 27 because it indicates that the transistor 27 is not performing the ON operation.

On the contrary, when the discharge current detection signal D2 is detected when the contactor 12 is on, that is, when the -15V power supply is applied to the control end (gate) of the discharging transistor 27. Indicates that the discharging transistor 27, which should not be turned on, is on, so that the control circuit 93 can detect the on-mode failure of the discharging transistor 27.

When the control circuit 93 detects these failures, it outputs an alarm. For example, a staff member is informed of the occurrence of a failure by sounding an alarm buzzer or lighting a failure display lamp. As a result, the staff can be encouraged to perform maintenance.

In FIG. 8, the first embodiment (FIG. 1)
However, it is needless to say that the same can be applied to the second to fifth embodiments (FIGS. 2, 4, 6, and 7).

[0070]

As described above, according to the present invention,
Since the discharge control operation can be performed only when the operation of the inverter is stopped and when the main power supply is cut off due to a power failure or the like, it is possible to provide an inverter control device with improved reliability.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of an inverter control device according to the present invention.

FIG. 2 is a block diagram showing a configuration of a second embodiment of an inverter control device according to the present invention.

FIG. 3 is a block diagram showing a configuration of a transistor drive circuit shown in FIG.

FIG. 4 is a block diagram showing a configuration of a third embodiment of an inverter control device according to the present invention.

5 is a block diagram showing a configuration of a transistor drive circuit shown in FIG.

FIG. 6 is a block diagram showing a configuration of a fourth embodiment of an inverter control device according to the present invention.

FIG. 7 is a block diagram showing a configuration of a fifth embodiment of an inverter control device according to the present invention.

FIG. 8 is a block diagram showing a configuration of a sixth embodiment of an inverter control device according to the present invention.

[Explanation of symbols]

11 Three-phase main power supply 12 contactors 13 Converter 14 Inverter 15 AC motor 17a, 17b Smoothing capacitor 18,92 Voltage detection circuit 19, 20 Current sensor 21 Speed detector 22, 34, 93 Control circuit 23, 24, 55, 86 Gate drive circuit 25 Discharge control circuit 26, 76, 78, 82, 84 Discharge resistance 27, 77, 79 discharge transistors 28, 63 a contact relay 29, 66, 83, 85 b contact relay 30, 36 Power supply backup circuit 31, 37, 65 Diode 32, 38, 44, 67 Supercapacitor 33, 56 transistor drive circuit 35, 75, 81 discharge circuit 41 Isolation amplifier circuit 42 Power supply control circuit 43 transformer 51 Rectifier 52 regenerative circuit 53 regenerative resistance 54 regeneration transistor 61 Regenerative control reference circuit 62 regenerative control circuit 9a, 9b Balance resistance 91 Discharge current detection resistor

Claims (6)

[Claims] 1. A converter for converting an AC power supply input via a contactor into a DC power supply; an inverter for converting the DC power supply output between the main circuit DC busbars by the converter into an AC power supply of an arbitrary frequency; A smoothing capacitor that is connected between the main circuit DC bus lines and that smoothes the DC power source; and a controller that controls the converter and the inverter based on the voltage across the terminals of the smoothing capacitor, the input state of the converter, the inverter output state, and the like. A discharge circuit connected in parallel with the smoothing capacitor, the discharge circuit including a discharge transistor and a discharge resistor connected to a current input side of the discharge transistor; and a control terminal of the discharge transistor. Two that are connected in common on the secondary side and open and close in conjunction with the on / off operation of the contactor A contact relay, a first contact relay that is closed when the contactor is on, a second contact relay that is closed when the contactor is off, and a power supply for turning off the discharge transistor on the primary side of the first contact relay. And transistor driving means for applying a power source for turning on the discharging transistor to the primary side of the second contact relay, and turning on the discharging transistor connected to the primary side of the second contact relay. An inverter control device comprising: a backup capacitor that is charged by a power supply for controlling the power supply; and a power backup circuit that includes a diode that blocks discharge from the backup capacitor to the power supply side in the event of a power failure. 2. A converter for converting an AC power supply connected via a contactor into a DC power supply; an inverter for converting the DC power supply output between the main circuit DC busbars by the converter into an AC power supply of an arbitrary frequency; A smoothing capacitor that is connected between the main circuit DC bus lines and that smoothes the DC power source; and a controller that controls the converter and the inverter based on the voltage across the terminals of the smoothing capacitor, the input state of the converter, the inverter output state, and the like. A discharging circuit connected in parallel with the smoothing capacitor, comprising a discharging transistor and a discharging resistor connected to a current input side of the discharging transistor, and a voltage between terminals of the smoothing capacitor A transistor that turns on the discharge transistor at least until it falls below a predetermined value. A register drive means, is charged by the DC power supply the converter output,
An inverter control device comprising: a backup capacitor that supplies power to the transistor driving means during a power failure; and a power backup circuit that includes a diode that blocks discharge from the backup capacitor to the power supply side during a power failure. . 3. The inverter control device according to claim 1, wherein the smoothing capacitor is formed by connecting a plurality of smoothing capacitors in series, and the discharge circuit is provided in each of the plurality of smoothing capacitors. An inverter control device characterized by being connected in parallel. 4. A converter for converting an AC power supply input via a contactor into a DC power supply; an inverter for converting the DC power supply output between the main circuit DC busbars by the converter into an AC power supply of an arbitrary frequency; A smoothing capacitor for smoothing a DC power supply, comprising a plurality of smoothing capacitors connected in series between the main circuit DC bus lines, a voltage between terminals of the plurality of smoothing capacitors, an input state of the converter, and an inverter output state. A control device for controlling the converter and the inverter based on the above, and a plurality of discharge circuits connected in parallel with each of the plurality of smoothing capacitors, the contacts being closed in response to an off operation of the contactor. A plurality of discharge circuits each including a relay and a discharge resistor connected to the current input side of the contact relay; Inverter control device, characterized in that. 5. The inverter control device according to claim 1, wherein a balance resistor is connected in parallel to each of the plurality of smoothing capacitors. 6. The inverter control device according to claim 1, wherein a current detection resistor inserted on the current output side of the discharge transistor or the contact relay and a voltage across the current detection resistor. A detection circuit for detecting the presence / absence of a detection voltage of the detection circuit and turning on of the contactor.
An inverter control device comprising: a determination unit that determines whether or not there is a failure based on an OFF operation.