JP4940286B2 - Capacitor discharge circuit - Google Patents

Description

  The present invention relates to a discharge circuit for a capacitor used in a DC circuit.

  Conventionally, an inverter called a three-level inverter, that is, a voltage divided by a plurality of capacitors, provides an intermediate potential point between the high potential point and the low potential point in addition to the high potential point and low potential point of the DC power supply. Inverters are known (see, for example, Patent Document 1 and Patent Document 2). As described above, in a circuit that uses a DC power supply divided by a capacitor, a circuit is provided that discharges the voltage of the capacitor when the device related to the circuit is stopped.

  FIG. 4 shows a configuration example of an inverter provided with a conventional capacitor discharge circuit. The inverter 49 shown in FIG. 4 includes a first antiparallel circuit composed of a switching element 52 and a diode 53, a second antiparallel circuit composed of a switching element 54 and a diode 55, and a third antiparallel circuit composed of a switching element 56 and a diode 57. An anti-parallel circuit, a circuit in which a fourth anti-parallel circuit composed of a switching element 58 and a diode 59 is connected in series, and the cathode of the diode 50 in the series circuit in which the anode of the diode 50 is connected to the cathode of the diode 51 Is connected between the first and second antiparallel circuits, the anode of the diode 51 is connected between the third and fourth antiparallel circuits, and between the second and third antiparallel circuits. This is a one-phase circuit of a three-level inverter provided with an AC voltage output terminal 60.

The cathode of the diode 53 that is the end of the first anti-parallel circuit of the inverter 49 is connected to the point P that is the high potential point of the DC power supply 41, and the diode 59 that is the end of the fourth anti-parallel circuit. The anode is connected to the N point which is a low potential point of the DC power supply 41. A switch 42 is provided between the DC power supply 41 and the point P. As a discharge circuit of the inverter 49, a first capacitor 43 is connected between a connection point (point C) of the diodes 50 and 51 and a point P, and a second capacitor 44 is connected between the point C and the point N. Is connected. In addition, a discharging resistor 45 and a discharging switch 46 are connected in series between the point P and the point N.
In such a circuit, the switch 42 is opened to stop the inverter, and then the discharge switch 46 is closed, so that the charging voltage of the capacitors 43 and 44 is discharged.

Japanese Patent Publication No.51-47848 JP-A-1-198280

  When the discharging switch 46 of the discharging circuit shown in FIG. 4 is closed to discharge the charging voltage of the capacitors 43 and 44, the charging voltage of each capacitor decreases toward 0 volts. When the discharge switch 46 is closed when the charge charges of the first capacitor 43 and the second capacitor 44 are different, the voltage of one capacitor becomes 0, and the discharge current from the other capacitor becomes one By flowing into the capacitor, a charge having a polarity opposite to that at the time of discharging is charged (see FIG. 4). For example, the charging voltage of the first capacitor 43 may be plus 100 volts, and the charging voltage of the second capacitor 44 may be minus 100 volts. In such a case, the points P and N may be Since the discharge ends when the voltage between them becomes 0 volts, the charged charges remain in the capacitors 43 and 44.

  FIG. 5 shows a configuration example of an inverter provided with a capacitor discharge circuit that solves such a problem. In the discharge circuit provided in this inverter, unlike the circuit shown in FIG. 4, a discharge resistor 47 and a discharge switch 48 are connected in series between the point C and the point P, and the discharge circuit is connected between the point C and the point N. A resistor 61 and a discharge switch 62 are connected in series. In this circuit, when the switch 42 is opened and the discharge switch 48 is closed, the voltage of the first capacitor 43 is discharged, and when the discharge switch 62 is closed, the voltage of the second capacitor 44 is discharged. As a result, the voltages of the capacitors 43 and 44 are both discharged to 0 volts.

  However, in the circuit as shown in FIG. 5, it is necessary to provide the same number of discharge resistors and discharge switches as the number of capacitors, and the discharge circuit and the apparatus including the discharge circuit are complicated and enlarged. Providing many switches leads to an increase in cost and a decrease in performance life. In particular, in capacitor discharge circuits applied to circuits such as inverters mounted on railway vehicles, it is necessary to use parts with very large external dimensions to withstand high voltages. Space is greatly increased.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a capacitor discharge circuit that can prevent the charge voltage of a plurality of capacitors from remaining and can be reduced in size and cost.

That is, the capacitor discharge circuit according to the present invention includes a first voltage dividing capacitor having one end connected to the high potential point of the DC power supply , one end connected to the low potential point of the DC power supply, and the other end connected to the first potential. A second voltage dividing capacitor connected to the other end of one voltage dividing capacitor; a first discharging resistor having one end connected to one end of the first voltage dividing capacitor; and a first insulated gate bipolar transistor And the collector of the second insulated gate bipolar transistor are connected to each other, and the first insulated gate bipolar transistor and the second insulated gate bipolar transistor are housed in a single package. A collector of the first insulated gate bipolar transistor is connected to the other end of the first discharging resistor, and the first insulated gate bipolar transistor A semiconductor element module in which an emitter and a collector of the second insulated gate bipolar transistor are both connected between the first voltage dividing capacitor and the second voltage dividing capacitor, and one end of the semiconductor element module in the semiconductor element module A second discharging resistor, the other end of which is connected to one end of the second voltage dividing capacitor, the first voltage dividing capacitor, and the second voltage dividing capacitor. Is connected to the input side of the inverter, the switch connected to the input side of the inverter is opened, and the voltage of the first voltage dividing capacitor is discharged by turning on the first insulated gate bipolar transistor. Then, when the second insulated gate bipolar is turned on, the voltage of the second voltage dividing capacitor is discharged. The features.
The capacitor discharge circuit according to the present invention includes a first voltage dividing capacitor having one end connected to the high potential point of the DC power source , one end connected to the low potential point of the DC power source, and the other end connected to the first potential source. A second voltage dividing capacitor connected to the other end of one voltage dividing capacitor; a first discharging resistor having one end connected to one end of the first voltage dividing capacitor; and a first insulated gate bipolar transistor And the collector of the second insulated gate bipolar transistor are connected to each other, and the first insulated gate bipolar transistor and the second insulated gate bipolar transistor are housed in a single package. A collector of the first insulated gate bipolar transistor is connected to the other end of the first discharge resistor, and A semiconductor element module in which both the collector and the collector of the second insulated gate bipolar transistor are connected between the first voltage dividing capacitor and the second voltage dividing capacitor, and one end of the semiconductor element module in the semiconductor element module A first discharging element connected to the emitter of the two insulated gate bipolar transistors, the other end connected to one end of the second voltage dividing capacitor, a first switching element and a first diode. Anti-parallel circuit, second anti-parallel circuit composed of second switching element and second diode, third anti-parallel circuit composed of third switching element and third diode, fourth switching element and A fourth anti-parallel circuit composed of four diodes is connected in series, and the anode of the sixth diode is connected to the cathode of the fifth diode. A cathode of the sixth diode in a series circuit to which a node is connected is connected between the first and second antiparallel circuits, and an anode of the fifth diode is the third and fourth antiparallel circuits. And an AC voltage output terminal is provided between the second and third antiparallel circuits, and the cathode of the first diode of the first antiparallel circuit is connected to the DC power supply. Connected to a high potential point, an anode of a fourth diode of the fourth anti-parallel circuit is connected to a low potential point of the DC power supply, and an intermediate terminal of the fifth and sixth diodes A three-level inverter connected to an intermediate terminal of the second voltage dividing capacitor, the switch on the input side of the three-level inverter is opened, and the first insulated gate bipolar transistor is turned on to turn on the first divided Pressure conde The voltage of the sensor is discharged, and when the second insulated gate bipolar is turned on, the voltage of the second voltage dividing capacitor is discharged .

  In the capacitor discharge circuit according to the present invention, it is possible to prevent the remaining charging voltage of a plurality of capacitors from being reduced, and to reduce the number of switches required for discharging and to reduce the cost.

The figure which showed the structural example of the inverter provided with the capacitor | condenser discharge circuit in the 1st Embodiment of this invention. The figure which showed the modification of the inverter shown in FIG. The figure which showed the structural example of the inverter provided with the capacitor | condenser discharge circuit in the 2nd Embodiment of this invention. The figure which showed the structural example (the 1) of the inverter provided with the conventional capacitor | condenser discharge circuit. The figure which showed the structural example (the 2) of the inverter provided with the conventional capacitor | condenser discharge circuit.

Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
First, a first embodiment of the present invention will be described.
FIG. 1 is a diagram illustrating a configuration example of an inverter including a capacitor discharge circuit according to the first embodiment of the present invention.
In the circuit shown in FIG. 1, a switch 12 and capacitors (voltage dividing capacitors) 13 and 14 are connected in series to a DC power supply 11. That is, one end of the first capacitor 13 is connected to the point P that is the high potential point of the DC power source 11, and the first point between the N point that is the low potential point of the DC power source 11 and the other end of the first capacitor 13. Two capacitors 14 are connected.

  A three-level inverter 19 composed of switching elements 22, 24, 26, 28 and diodes 20, 21, 23, 25, 27, 29 is provided at points P, N, and C, which is a connection terminal for the capacitors 13, 14. Are connected. The cathode of the diode 23 at one end of the three-level inverter 19 is connected to the point P, and the anode of the diode 29 at the other end of the three-level inverter 19 is connected to the point N.

  The connection point between the anode of the diode 20 and the cathode of the diode 21, which is the intermediate potential point of the three-level inverter 19, is connected to the intermediate terminals (point C) of the capacitors 13 and 14. An AC voltage output terminal 30 is provided between the anode of the diode 25 and the cathode of the diode 27. Since the operation of the three-level inverter 19 is the same as that conventionally known and is not related to the present invention, the description thereof is omitted.

  One end of the first discharging resistor 15 is connected to the point P, one end of the discharging switch 16 is connected to the other end of the first discharging resistor 15, and the other end of the discharging switch 16 is connected to the N point. The second discharge resistor 17 is connected between the two. The resistance values of the discharge resistors 15 and 17 are the same.

  The anode of the first diode 31 and the cathode of the second diode 32 are connected to the point C. The cathode of the first diode 31 is connected between the first discharging resistor 15 and the discharging switch 16, and the anode of the second diode 32 is connected between the second discharging resistor 17 and the discharging switch 16. Is done.

  In such a circuit, when the three-level inverter 19 is used, the switch 12 is closed and the discharge switch 16 is opened. If the discharge switch 16 remains open even if the switch 12 is opened to stop the use of the three-level inverter 19, no current flows through the discharge resistors 15 and 17, but no discharge occurs. When the discharge switch 16 is closed, the charging voltage of the first capacitor 13 is discharged through the first discharge resistor 15, the discharge switch 16, and the second diode 32 as indicated by an arrow A. As indicated by the arrow B, the charging voltage of the second capacitor 14 is discharged through the first diode 31, the discharging switch 16, and the second discharging resistor 17.

  Here, if the charging voltage and the discharge time constant at the start of discharging of the capacitors 13 and 14 are exactly the same, there is a potential difference between the anode and cathode of the first diode 31 and between the anode and cathode of the second diode 32. Since no current is generated, no current flows through the diodes 31 and 32, and a discharge current from the capacitors 13 and 14 flows through the route of the first discharge resistor 15, the discharge switch 16, and the second discharge resistor 17. That is, only the discharge current generated by the difference between the charging voltages of the capacitors 13 and 14 and the discharge time constant flows through the diodes 31 and 32, so that the current capacity of the diodes 31 and 32 may be small.

  Further, when the charging voltages of the capacitors 13 and 14 at the start of discharging are different, discharging is started only from a capacitor having a high charging voltage, and discharging from the other capacitor is not performed. For example, if the charging voltage of the first capacitor 13 is higher than the charging voltage of the second capacitor 14, a forward voltage is generated between the anode and the cathode of the second diode 32, and the first discharging resistor described above is used. 15. Discharge occurs at the route of the discharge switch 16 and the second diode 32. Further, if the charging voltage of the second capacitor 14 is higher than the charging voltage of the first capacitor 13, a forward voltage is generated between the anode and the cathode of the first diode 31, and the first diode 31, Discharge occurs along the route of the discharge switch 16 and the second discharge resistor 17.

  As a result of the discharge from only one capacitor, when the charging voltages of both capacitors become the same, the first discharging resistor 15, the discharging switch 16, and the second discharging resistor 17 as described above. Discharge current flows through the route. When the discharge time constants of the capacitors 13 and 14 are different, the capacitor previously discharged to 0 volts stops discharging and the voltage does not change thereafter. For example, when the discharge of the second capacitor 14 is stopped first and the voltage of the first capacitor 13 is not discharged to 0 volts, the first discharge resistor 15, the discharge is discharged from the first capacitor 13. The discharge of the capacitors 13 and 14 is stopped by continuously discharging at the route of the switch 16 and the second diode 32 and discharging to 0 volts.

  As described above, since the discharge of the charging voltage of the two capacitors can be performed in accordance with the operation of one discharging switch, the number of switches necessary for discharging is prevented while preventing the remaining charging voltage of the plurality of capacitors. Accordingly, the circuit for driving the switch can also be reduced, so that the circuit can be downsized and the cost can be reduced. In addition, since the movable parts are reduced, the performance life of the circuit can be extended. In particular, when the capacitor discharge circuit is applied to a circuit such as an inverter mounted on a railway vehicle, it is necessary to greatly increase the external shape of the components of the discharge circuit, so that the effect is great.

FIG. 2 shows a modification of the inverter shown in FIG.
In this modification, a switching semiconductor element 33 is used in place of the discharge switch 16 shown in FIG. When a thyristor is used as the switching semiconductor element 33, the anode of the thyristor is connected between the first diode 31 and the first discharge resistor 15, and the cathode of the thyristor is connected to the second diode 32 and the second discharge. It connects between the resistors 17 for use. When a control signal is applied to the gate of this thyristor to turn it on, the same discharge as when the discharge switch 16 shown in FIG. 1 is closed occurs.

  The switching semiconductor element 33 may be a self-extinguishing semiconductor element such as a GTO thyristor (Gate Turn Off Thyristor) or an IGBT (Insulated Gate Bipolar Transistor).

  When a GTO thyristor is used as the switching semiconductor element 33, the anode is connected between the first diode 31 and the first discharge resistor 15 and the cathode is connected to the second diode 32 and the second diode 32, as in the thyristor described above. Connected between two discharge resistors 17. When an IGBT is used as the switching semiconductor element 33, the collector is connected between the first diode 31 and the first discharge resistor 15, and the emitter is connected to the second diode 32 and the second discharge resistor 17. Connect between.

  The IGBT can increase the switching frequency as compared with the GTO thyristor. As described above, when either IGBT or GTO thyristor is used, the switching semiconductor element 33 can be used not only as a discharge switch but also as a chopper by applying a control signal to the gate. Discharging can be performed while controlling the power between point P and point N with the discharge resistors 15 and 17.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. FIG. 3 is a diagram illustrating a configuration example of an inverter including the capacitor discharge circuit according to the second embodiment of the present invention. The configuration of the inverter to which the capacitor discharge circuit according to the present embodiment is applied is basically the same as that shown in FIG. Shall be omitted.
In the circuit shown in FIG. 3, a semiconductor element module 34 is used in place of the discharging switch 16 and the diodes 31 and 32 used in the circuit shown in FIG.

  The semiconductor element module 34 is a so-called 2-in-1 module in which the emitter of the first IGBT 34a and the collector of the second IGBT 34b are connected and housed in a single package. The first discharging resistor 15 is connected between the point P and the collector of the first IGBT 34a, and the second discharging resistor 17 is connected between the point N and the emitter of the second IGBT 34b. The emitter of the first IGBT 34a and the collector of the second IGBT 34b are both connected to the point C.

  In this circuit, when the switch 12 is opened and a control signal is input to the gate of the first IGBT 34a to turn it on, the voltage of the first capacitor 13 becomes the root of the first discharge resistor 15 and the first IGBT 34a. When the control signal is input to the gate of the second IGBT 34 b and turned on, the voltage of the second capacitor 14 is discharged through the route of the second IGBT 34 b and the second discharge resistor 17. As a result, the voltages of the capacitors 13 and 14 are discharged to 0 volts. By performing control via the gates of the first IGBT 34a and the second IGBT 34b, the functions of the discharge switch and the chopper switch can be realized.

  As described above, when the semiconductor element module 34 in which a plurality of semiconductor elements are housed in the same package is used in the discharge circuit, the cost of using the first IGBT device and the second IGBT as a single device instead of the semiconductor element module 34 is as follows. The cost is significantly lower than the cost when using a circuit in which IGBT devices (not shown) are connected in series. The size of the semiconductor element module 34 is significantly smaller than the combined size of the first IGBT device and the second IGBT device. That is, it is possible to significantly reduce the size and cost as compared with the capacitor discharge circuit used conventionally.

  In the embodiment described above, the capacitor discharge circuit is used by being connected to a three-level inverter including a diode and a switching element. However, the present invention is not limited to this and is a circuit provided with a high potential point, a low potential point, and an intermediate potential point. If it exists, it may be used by connecting to another circuit.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

  DESCRIPTION OF SYMBOLS 11 ... DC power supply, 12 ... Switch, 13 ... 1st capacitor | condenser, 14 ... 2nd capacitor | condenser, 15 ... 1st resistor for discharge, 16 ... Switch for discharge, 17 ... 2nd resistor for discharge, 19 ... 3 Level inverter, 31 ... first diode, 32 ... second diode, 33 ... switching semiconductor element, 34 ... semiconductor element module.

Claims (2)

A first voltage dividing capacitor having one end connected to a high potential point of the DC power supply;
A second voltage dividing capacitor having one end connected to the low potential point of the DC power supply and the other end connected to the other end of the first voltage dividing capacitor;
A first discharging resistor having one end connected to one end of the first voltage dividing capacitor;
The emitter of the first insulated gate bipolar transistor and the collector of the second insulated gate bipolar transistor are connected, and the first insulated gate bipolar transistor and the second insulated gate bipolar transistor are contained in a single package. The collector of the first insulated gate bipolar transistor is connected to the other end of the first discharge resistor, and the emitter of the first insulated gate bipolar transistor and the collector of the second insulated gate bipolar transistor. Are both connected between the first voltage dividing capacitor and the second voltage dividing capacitor;
A second discharge resistor having one end connected to the emitter of the second insulated gate bipolar transistor in the semiconductor element module and the other end connected to one end of the second voltage dividing capacitor;
An inverter connected to the input side of the first voltage dividing capacitor and the second voltage dividing capacitor;
The switch connected to the input side of the inverter is opened, and the first insulated gate bipolar transistor is turned on, whereby the voltage of the first voltage dividing capacitor is discharged and the second insulated gate bipolar is turned on. This discharges the voltage of the second voltage dividing capacitor . A first voltage dividing capacitor having one end connected to a high potential point of the DC power supply;
A second voltage dividing capacitor having one end connected to the low potential point of the DC power supply and the other end connected to the other end of the first voltage dividing capacitor;
A first discharging resistor having one end connected to one end of the first voltage dividing capacitor;
The emitter of the first insulated gate bipolar transistor and the collector of the second insulated gate bipolar transistor are connected, and the first insulated gate bipolar transistor and the second insulated gate bipolar transistor are contained in a single package. The collector of the first insulated gate bipolar transistor is connected to the other end of the first discharge resistor, and the emitter of the first insulated gate bipolar transistor and the collector of the second insulated gate bipolar transistor. Are both connected between the first voltage dividing capacitor and the second voltage dividing capacitor;
A second discharge resistor having one end connected to the emitter of the second insulated gate bipolar transistor in the semiconductor element module and the other end connected to one end of the second voltage dividing capacitor;
A first anti-parallel circuit composed of a first switching element and a first diode, a second anti-parallel circuit composed of a second switching element and a second diode, and a third switching element and a third diode. The circuit includes a third antiparallel circuit, a circuit in which a fourth antiparallel circuit composed of a fourth switching element and a fourth diode is connected in series, and the anode of the sixth diode is connected to the cathode of the fifth diode The cathode of the sixth diode in the connected series circuit is connected between the first and second antiparallel circuits, and the anode of the fifth diode is connected between the third and fourth antiparallel circuits. And an AC voltage output terminal is provided between the second and third antiparallel circuits, and a cathode of the first diode of the first antiparallel circuit is a high potential point of the DC power supply. Connected with The anode of the fourth diode of the fourth anti-parallel circuit is connected to the low potential point of the DC power supply, and the intermediate terminals of the fifth and sixth diodes are the first and second voltage dividing capacitors. A three-level inverter connected to the intermediate terminal ,
When the switch on the input side of the three-level inverter is opened and the first insulated gate bipolar transistor is turned on, the voltage of the first voltage dividing capacitor is discharged, and the second insulated gate bipolar is turned on. A capacitor discharging circuit , wherein the voltage of the second voltage dividing capacitor is discharged .

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