JPH033473B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of an inverter device, and particularly to an improvement of an inverter device suitable for downsizing the device and taking measures against induced disturbances.

[Conventional technology]

FIG. 1 shows an example of the main circuit configuration of a three-phase GTO inverter device to which the present invention can be applied. In the figure, 1 is a filter capacitor connected to the power supply, 2
is a three-phase inverter consisting of phase arms 21, 22, and 23 forming U, V, and W phases. Each phase arm includes GTOs 31 to 36, freewheel diodes 41 to 46, diodes 51 to 56 constituting a snubber, capacitors 61 to 66, and resistors 71 to 76. 81 to 85 indicate wiring inductances. An induction motor 9 is connected as a load of the inverter.

In the inverter, the GTOs of each phase alternately and periodically turn on and off, supplying three-phase alternating current to the electric motor 9.

Here, an example of the operation of the inverter will be explained.

Now, the positive side GTO31 of U phase and the negative side GTO of V phase
34 is on, the load current flows from the filter capacitor 1 to the wiring inductance 81, the GTO 31, the wiring inductance 83, the U-V phase of the motor 9, the wiring inductance 84,
It flows to the filter capacitor 1 via the GTO 34 and wiring inductance 82. Next GTO31
When turned off, the motor current continues as a circulating current flowing through the U-phase freewheel diode 42 and the GTO 34 due to the motor 9 and wiring inductances 83 and 84. Next, W phase GTO35
When turned on, the load current flows through the GTO 35, the wiring inductance 85, the W-V phase of the motor, the wiring inductance 84, and the GTO 34. By repeating such a commutation operation by the inverter, three-phase alternating current can be provided to the electric motor 9.

Now, if we pay attention to the operation immediately after GTO31 is turned off, we can see that the wiring inductance 81 between filter capacitor 1 and GTO31 is
The energy stored in the GTO 31 is transferred to the off state through the snubber diode 51 and is transferred to the snubber capacitor 6 as shown by the solid arrow.
1 is charged, increasing the voltage of the snubber capacitor 61. This capacitor voltage is GTO
A voltage V _AK is applied between the anode and cathode of 31. This voltage V _AK must be kept as low as possible to protect the GTO. GTO3 at this time
The current i _A and voltage V _AK of 1 change as shown in FIG. 3, and the peak voltage V _DOP is expressed by the following equation.

Here, the power supply voltage V _S and the cut-off current (current flowing through the GTO 31) I _T are uniquely determined by the circuit. In order to reduce the peak voltage V _DOP applied to the GTO 31, as can be seen from the above equation, there are two methods: reducing the wiring inductance 81 (ie, L ₁ ) and increasing the capacitance C _S of the snubber capacitor 61. The latter has the disadvantage that the snubber resistor 71, which receives the discharge energy of the snubber capacitor 61 shown by the dashed arrow in FIG. 2, also becomes large, resulting in a large device.

On the other hand, the wiring inductance 81 (i.e. L ₁ )
Possible ways to reduce this include wiring reciprocating conductors closely together or using concentric cables. Although these methods can reduce inductance compared to single wire wiring, they are not sufficient and have the problem of increasing production costs.

In this way, if the wiring inductance can be reduced, the voltage applied to the semiconductor element having a self-extinguishing function can be suppressed to a low level, and the semiconductor element can be more safely protected. Furthermore, if the semiconductor element can operate at the same peak voltage, the capacitance of the snubber capacitor can also be reduced, as seen from the previous equation, and the device can also be made smaller.

However, in inverter trains, the inverter circuit components are large and the equipment is also large, so the U, V, W21 of the inverter using GTO is
23 and the power supply filter capacitor 1 were housed in separate boxes, and these were connected by the aforementioned reciprocating conductor or concentric cable.

[Problem to be solved by the invention]

If these boxes are installed under the floor of a train, they will be placed 1 to 2 meters apart.
Therefore, the inductance of the wiring between them is also several μH.
As mentioned above, the capacitor of the snubber circuit,
The capacitance of the resistor must be increased. As the capacity of these devices increases, the size of the device itself also increases, so increasing the size of the entire device has become an unavoidable problem with conventional structures.

Additionally, the filter capacitor storage box and GTO storage box are installed separately under the floor. Therefore, the wiring between them becomes long. Also, the wiring that crosses between boxes ends up outside the box. These factors cause a problem of induction disturbances in equipment installed on the ground (signal lines, etc.).

An object of the present invention is to reduce the size of an inverter device and to prevent induction failures due to long wiring.

[Means to solve the problem]

In order to achieve the above object, a semiconductor element with a self-extinguishing function is divided and arranged for each phase at linear intervals, a filter capacitor is arranged between each phase, and the semiconductor element and the filter capacitor are arranged separately. are stored together in a box.

[Effect]

When a semiconductor element and a filter capacitor are simply housed in an integrated box, for example, the filter capacitor, U
In the case where the semiconductor elements are arranged in an integrated box with a configuration such as phase, V phase, and W phase, and in the device of the present invention, semiconductor elements are divided and arranged directly for each phase at intervals, and between each phase, The difference from the case where filter capacitors are arranged individually and housed in an integrated box will be explained.

The semiconductor elements constituting the U-phase, V-phase, and W-phase are housed in a cooling device container for each phase, and the size thereof is considerable.

Furthermore, when the induction motor 9 in FIG. 1 is carrying a load, the discharge current of the filter capacitor 1 flows to each phase of the semiconductor device, and when the induction motor 9 releases electrical energy, the current flows through the semiconductor device. flows into the filter capacitor 1 from each phase and charges the filter capacitor.

Taking these conditions into account, we will compare the former case where the semiconductor device is simply housed in an integrated box and the latter case where a filter capacitor is placed between each phase of the semiconductor device and the semiconductor device is housed in an integrated box. In the former case, when considering the charging/discharging relationship between the filter capacitor and each phase, there is a considerable difference in the wiring length between the filter capacitor U phase and the filter capacitor W phase, and the wiring inductance also varies considerably depending on the wiring length. occurs. In other words, the W-phase snubber circuit must have a larger capacity and volume than the U-phase snubber circuit. However, unless the elements of each phase are equal, balance cannot be achieved, so the snubber circuits of all phases must be equal. In other words, U-phase and V-phase snubber circuits are created in accordance with the W-phase snubber circuit. In the end, even if it is an integrated box, the device becomes larger due to the extra size of the snubber circuit.

The latter device of the present invention is arranged, for example, as U-phase filter capacitor, V-phase, filter capacitor, W-phase. With this configuration, the average distance between the filter capacitor and each phase is shorter than the former, and the wiring inductance is also smaller.
Furthermore, the wiring lengths between the filter capacitor and each phase are approximately equal, and the wiring inductances are also approximately equal.

In addition, since the wiring that acts as an antenna has been shortened, interference with induction to ground equipment (mainly signals) caused by charging and discharging between the filter capacitor and each phase can be prevented.

Furthermore, since the filter reactor and semiconductor element are housed in an integrated box, harmful radio waves are shielded.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. In the figure, 21, 22, and 23 are devices for the U-phase, V-phase, and W-phase arms of the GTO inverter, and the filter capacitor 1 is composed of two filter capacitor units 11 and 12,
It is stored between each phase arm inside the inverter box 20. 30 indicates a gate device etc. for driving the GTO.

In this device, the GTO and filter capacitor of each phase that make up the inverter are placed close to each other, so the wiring length between the GTO and the filter capacitor can be shortened, and the charging between the filter capacitor and the semiconductor elements of each phase can be shortened. From the viewpoint of discharge, the wiring inductance can be made extremely small. As a result, if the peak voltage V _DOP applied to the GTO is suppressed to a predetermined value, the capacitance of the snubber capacitor can be reduced. In addition, the capacity of the snubber resistor that absorbs and dissipates the discharge energy of this capacitor can be made smaller, which makes it possible to reduce the amount of heat generated (energy saving) and downsize the device.

Since these snubber resistors and capacitors are inserted into each arm of the inverter, the miniaturization of each device has a large effect in contributing to the miniaturization of the device (box). In particular, since an inverter device mounted under the floor of a vehicle is required to occupy a small space, the practical effects are significant.

Further, since the wiring is shortened, it is possible to prevent interference with induction of signals and the like.

〔Effect of the invention〕

According to the present invention, since the inductance of wiring can be reduced, it is possible to reduce the size of the snubber, and thereby to prevent the device from becoming smaller and induction failures.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an example of an inverter main circuit to which the present invention can be applied, Fig. 2 is an explanatory diagram of the operation of the snubber circuit of Fig. 1, Fig. 3 is a current voltage waveform diagram when semiconductor elements are off, and Fig. 4 FIG. 2 is a side view showing wiring of an inverter device according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1, 11, 12... Filter capacitor, 2... Inverter, 20... Inverter box, 21-23... Inverter each phase arm, 31-36... Semiconductor element with self-extinguishing function.

Claims (1)

[Claims] 1. In an inverter device configured using a semiconductor element with a self-extinguishing function, each phase arm is connected in parallel to a DC power supply, and a filter capacitor is connected to the DC side, the filter capacitor is divided, The semiconductor element is linearly divided and arranged at intervals for each phase arm, and the divided filter capacitors are arranged in the spaces between the respective phases, and the filter capacitor and the semiconductor element are placed in the same box. Inverter device stored inside.