JP3071944B2 - Electric vehicle power converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric vehicle which is supplied with DC power from an overhead wire or a third rail, and in which the inverter circuit is continuously operated even when the current supply is temporarily stopped due to the disconnection of the pantograph. The present invention relates to a power converter for an electric vehicle that can be operated and can continue to supply power to a load.

[0002]

2. Description of the Related Art In an electric vehicle which is supplied with DC power from a DC overhead line or a third rail, a conventional power conversion device is provided as a power conversion device provided for supplying power to various loads such as an air conditioner and a lighting device. Generally, inverter circuits are widely used.

[0003] A conventional power converter for an electric vehicle using an inverter circuit has a configuration as shown in FIG. 7. DC power flowing through an overhead wire or a third rail 1 is collected by a pantograph 2, and a unit switch 3 is provided. Through the DC filter reactor 4 and the GTO circuit breaker 5 to charge the filter capacitor 6 and supply DC power to an inverter circuit 7 connected in parallel with the filter capacitor 6. A voltage detector 8 is connected in parallel with the filter capacitor 6 so that the voltage of the filter capacitor 6 is detected. The charging resistor 9 provided in parallel with the GTO breaker 5 is for charging the filter capacitor 6 at the time of starting, and is short-circuited by the GTO breaker 5 after charging.

The inverter circuit 7 has a three-phase structure, and each arm has an IGBT or GTO or other switching elements 71 to 76 as shown in FIG.

Further, a discharge current from the filter capacitor 6 is detected between the filter capacitor 6 and the inverter circuit 7 when one of the switching elements 71 to 76 in the inverter circuit is broken and the upper and lower arms are short-circuited. Then, a current detector 10 for turning off the GTO circuit breaker 5 to cut off the unit switch 3 and preventing current from flowing from the overhead wire or the third rail 1 is arranged.

[0006] A transformer 12 is connected to the output side of the inverter circuit 7 via an AC filter 11, so that the output of the transformer 12 is supplied to various loads of the electric vehicle.

[0007] In such a conventional electric power converter for an electric vehicle, especially when there is only one pantograph 2 for the traveling electric vehicle, the pantograph 2 is connected to the overhead wire or the third rail during traveling. When the disconnection phenomenon that the 1 is separated occurs, the supply of the DC power to the inverter circuit 7 is temporarily cut off. Although the disconnection time varies depending on the line segment, in the conventional power converter of an electric vehicle shown in FIG. 7, the operation continuation time of the inverter circuit 7 at the time of disconnection is generally several ms to several tens ms. However, it is ideally desirable that the operation continuation time can be extended until the disconnection is eliminated. Therefore, in order to extend the operation duration of the inverter circuit at the time of disconnection, the output power is conventionally reduced, or an enormous amount of the capacitor bank 13 is connected in parallel with the filter capacitor 6 as shown in FIG. It was additionally installed in order to cope with the voltage drop at the time of disconnection.

However, when the filter capacitor bank 13 is additionally provided externally as described above, there are the following problems.

If the input current of the inverter circuit 7 is i, i = capacity of the inverter circuit × power factor / (efficiency × DC input voltage) (1) iΔt = CΔV (2)

In the case of an electric vehicle, the overhead wire or the third rail 1, which is a power supply source, fluctuates by ± 50% or more of the rated value. Therefore, when configuring a filter capacitor, the rated +50
% Is required for the capacitor. For example, when the overhead wire voltage is 1500 V and a filter capacitor is configured by a capacitor of 400 V-3300 μF,
8S to 9S (S means series connection) in consideration of a margin.

Therefore, in the electric vehicle power converter shown in FIG. 8, if a disconnection of 60 ms occurs at a capacity of 200 kVA and a DC of 1500 V as shown in FIG. 9, a power factor of 0.85 and an efficiency of 0.9 (general) The capacitor capacity required for the capacitor bank 13 is calculated from the above equations (1) and (2) and the graph of FIG. 9 as follows: i = 200 × 10 ³ VA × 0.85 / (0.9 × 1500 V) = about 126 A 126 A × 60 ms = C × (1500 V−900 V) Therefore, C = about 12600 μF. Note that FIG. 9 shows the behavior of the inverter input voltage at the time of disconnection under the condition that the input of the inverter circuit 7 performs low-voltage detection at 900 V DC and stops the inverter circuit.

For this reason, the filter capacitor 6 is usually
Since a 9S9P (P means a parallel number) configuration is used, the external filter capacitor bank 13 needs a capacitor bank composed of an enormous number of capacitors of 9S25P (9167 μF, 225). there were.

By the way, in order to extend the operation duration of the inverter circuit when the pantograph is disconnected by such an external filter capacitor bank, the external filter capacitor bank composed of a large number of capacitors as described above must be used. However, when such a large-capacity external filter capacitor bank is used, the large current charged in the external filter capacitor bank is rapidly discharged when a short circuit accident occurs in the arm of the inverter circuit. This may cause a problem that the switching element of the inverter circuit is destroyed.

For example, in the conventional power converter shown in FIG. 8, when the switching element 72 is destroyed while the switching elements 71 and 76 of the inverter circuit 7 are in an ON state, the switching elements 71 and 72 are short-circuited. State. In this case, in the device without the external filter capacitor bank 13 as shown in FIG. 7, the DC current from the overhead wire or the third rail 1 and the discharge current from the filter capacitor 6 try to flow into the inverter circuit 7. When the current detector 8 detects this current value and turns off the GTO breaker 5 and cuts off the unit switch 3, the DC current from the overhead wire or the third rail 1 is cut off, and the discharge from the filter capacitor 6 is discharged. Since only the current flows through the inverter circuit 7, the degree of damage of the switching element can be reduced.

However, in the power converter having the external filter capacitor bank 13 as shown in FIG. 8, even if the GTO circuit breaker 5 is turned off and the unit switch 3 is shut off, the power from the external filter capacitor bank 13 is excessive. Since the current is emitted, there is a problem that the switching element may be destroyed in some cases and components around the element may be damaged.

[0016]

As described above, in the conventional electric vehicle power converter, in order to extend the operation duration of the inverter circuit at the time of disconnection, an enormous amount of capacitor is required for the filter capacitor. However, there is a problem that an external filter capacitor bank having a high withstand voltage must be added or the performance must be limited.

When an external filter capacitor bank is additionally installed, when a short circuit accident occurs in the switching element of the inverter circuit, the discharge current suddenly flows from the external filter capacitor bank into the short-circuited switching element portion. In addition, there is a problem that the switching element may be destroyed on a large scale.

The present invention has been made in view of such a conventional problem, and an external filter capacitor bank composed of a relatively small amount of a low withstand voltage capacitor and a simple peripheral circuit have been added. An object of the present invention is to provide a power conversion device for an electric vehicle that can extend the operation continuation time of an inverter circuit with respect to a disconnection.

Another object of the present invention is to provide a power conversion device for an electric vehicle which can minimize damage such as destruction of an inverter circuit when a short circuit accident occurs in a switching element of the inverter circuit. .

[0020]

According to the first aspect of the present invention,
An electric vehicle that takes in DC power from an overhead wire or a third rail via a pantograph, supplies it to an inverter circuit connected in parallel to it via a filter capacitor, converts DC / AC power, and supplies it to various loads of an electric vehicle Power converter, an external filter capacitor bank comprising a self-extinguishing semiconductor device, a plurality of capacitors charged through the self-extinguishing semiconductor device, and the external filter capacitor in parallel with the filter capacitor. A rectifying element that permits only discharge from the bank to the DC input side of the inverter circuit, and a voltage across the external filter capacitor bank is detected, and this voltage is lower than the rated value of the input DC voltage of the inverter circuit. Means for controlling on / off operation of the self-extinguishing semiconductor device so as to maintain a predetermined set voltage It is those with a.

According to a second aspect of the present invention, in the electric vehicle power converter, a plurality of capacitors connected in parallel to the filter capacitor for supplying DC power to the inverter circuit even in the event of an instantaneous disconnection of the pantograph. Detecting the external filter capacitor bank and the discharge current value from the external filter capacitor bank,
Means for electrically disconnecting the inverter circuit from the external filter capacitor bank when an arm short circuit occurs in the inverter circuit.

According to a third aspect of the present invention, in the power conversion device for an electric vehicle, the power conversion device includes:
A self-extinguishing type semiconductor element, an external filter capacitor bank including a plurality of capacitors charged through the self-extinguishing type semiconductor element, and discharging from the external filter capacitor bank to a DC input side of the inverter circuit. And a voltage between both ends of the external filter capacitor bank, and a self-supply voltage so as to maintain a predetermined voltage lower than a rated value of the input DC voltage of the inverter circuit. Means for controlling the on / off operation of the arc-shaped semiconductor element, detecting a discharge current value from the external filter capacitor bank, and electrically connecting the inverter circuit and the external filter capacitor bank when an arm short circuit occurs in the inverter circuit. And means for shutting off.

[0023]

In the electric vehicle power converter according to the first aspect of the present invention, during normal operation, the voltage of the external filter capacitor bank is reduced from the rated voltage via the self-extinguishing type semiconductor element by the control of the voltage detecting means. To maintain a low predetermined voltage.

When the pantograph is disconnected, when the DC input voltage decreases to a predetermined value while the inverter circuit continues to operate and becomes equal to the voltage across the external filter capacitor bank, the rectifying element operates to activate the external filter. The current charged in the attached filter capacitor bank is discharged to the inverter circuit, and the operation of the inverter circuit is continued for a longer time.

Thus, by continuing the operation of the inverter circuit by discharging the external filter capacitor bank at a set voltage lower than the rated voltage, the operation continuation time can be extended.

In the power converter for an electric vehicle according to the present invention, when a switching element of the inverter circuit is broken and a short circuit occurs between the upper and lower arms, an overcurrent is discharged from the external filter capacitor bank. Is detected, the inverter circuit and the external filter capacitor bank are electrically disconnected, and an excessive discharge current from the external filter capacitor bank is prevented from suddenly flowing into the inverter circuit. Destruction can be minimized.

In the power converter for an electric vehicle according to the third aspect of the present invention, during normal operation, the rated voltage is supplied to the external filter capacitor bank via the self-extinguishing type semiconductor element by the control of the voltage detecting means. The pantograph is charged so as to maintain a predetermined lower voltage, and when the pantograph is disconnected, the DC input voltage decreases to a predetermined value while the inverter circuit continues to operate, and the voltage across the external filter capacitor bank is reduced. When they become equal, the rectifying element operates to discharge the current charged in the external filter capacitor bank to the inverter circuit, and to continue the operation of the inverter circuit for a longer time, so that the inverter circuit operates at a set voltage lower than the rated voltage. The operation of the inverter circuit can be continued by discharging the external filter capacitor bank.

In addition, when the switching element of the inverter circuit is destroyed and the upper and lower arms are short-circuited, it is detected that an overcurrent is discharged from the external filter capacitor bank, and the inverter circuit and the external circuit are connected. The filter capacitor bank is electrically cut off, and an excessive discharge current from the external filter capacitor bank is prevented from suddenly flowing into the inverter circuit, thereby minimizing element destruction of the inverter circuit.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a circuit block diagram of an embodiment of the first aspect of the present invention. Portions common to the circuit components of FIGS. 7 and 8 shown as conventional examples are denoted by the same reference numerals. Shown.

As a feature of this embodiment, an element newly added to the conventional example is an external filter capacitor bank 14 provided in parallel with the fill capacitor 6, and the voltage across the filter capacitor 6 is higher than the rated voltage of 1500 V. The rectifying element 15 allows only the external filter capacitor bank 14 to discharge when the voltage becomes lower than a predetermined voltage, for example, 1100 V or less.

GTO as self-extinguishing rectifier
Thyristor 16, external filter capacitor bank 14
, A voltage detector 17 as a means for turning on the gate of the GTO thyristor 16 when the voltage becomes equal to or lower than a predetermined set voltage, and a current for each of the GTO thyristor 16 and the voltage detector 17. Limiting resistors 18 and 19 for limiting are provided.

Next, the operation of the electric vehicle power converter having the above configuration will be described.

When the pantograph 2 is in contact with the overhead wire or the third rail 1 and the electric vehicle is running while collecting power, the DC power of the rated voltage 1500 V collected by the pantograph 2 is supplied to the filter reactor 4 and the filter capacitor 6. , And is converted into a direct current and an alternating current, and output to various loads as an alternating current of a predetermined voltage.

At this rating, the voltage detector 17 detects the voltage across the external filter capacitor bank 14 until the external filter capacitor bank 14 is charged to a predetermined set voltage, and the voltage is the set voltage. 110
The gate of the GTO thyristor 16 is turned on until the voltage becomes 0 V to perform charging.

When the voltage across the external filter capacitor bank 14 reaches the set voltage 1100 V, the voltage detector 17 detects this and turns off the gate of the GTO thyristor 16 to stop charging.

Thereafter, the voltage detector 17 always detects the voltage across the external filter capacitor bank 14,
Each time the voltage at both ends becomes equal to or lower than the set voltage 1100 V due to the discharge, the gate of the GTO thyristor 16 is turned on and recharging is repeated.

Therefore, when the pantograph 2 is disconnected from the overhead wire or the third rail 1 during operation at the rated voltage of 1500 V, as shown in FIG. 2, a predetermined set voltage of 1100 V lower than the rated voltage of 1500 V until about 10 ms. During this time, the inverter circuit 7 operates continuously.

When the voltage drops to 1100 V, the voltage across the external filter capacitor bank 14 becomes equal to the voltage across the filter capacitor 6, and the rectifier 15 turns on to charge the external filter capacitor bank 14. The generated current is discharged and output to the inverter circuit 7. After that, the operation of the inverter circuit 7 is continued by the discharge current of the external filter capacitor bank 14 until about 60 ms when the stop voltage of the inverter circuit 7 reaches 900 V.

Here, if the circuit is disconnected for 60 ms by a 1500 V overhead line 200 kVA inverter circuit, a capacitor bank having a capacity of 12600 μF is required in the conventional example in order to obtain a filter capacitor voltage as shown in FIG. In addition to the 9S9P filter capacitor 6, a 9167 μF
It was necessary to add 225 external filter capacitor banks connected to S25P.

On the other hand, in the above-described embodiment, as shown in FIG.
While the voltage drops to 00 V, power is not supplied from the external filter capacitor bank 14, and power is supplied from the external filter capacitor bank 14 added between the set voltage 1100 V and the protection voltage set value of 900 V. I have to. Therefore, the time Δt required for the voltage to drop to 1100 V is given by the following equation (2): 126 A × Δt = 3300 μF × (1500 V-1100 V), and Δt = about 10 ms.

Further, the capacitance C of the external filter capacitor bank 14 required when the voltage from 1100 V to 900 V decreases is calculated from the above-mentioned equations (1) and (2) as follows: i = 200 × 10 ³ VA × 0. 85 / (0.9 × 1100V) = about 172A 172A × (60ms-10ms) = C × (1100V-900V), and C = about 43000 μF. At this time, since the voltage applied to the external filter capacitor bank 14 is 1100 V at the maximum, a capacitor having a rated voltage of 400 V can be realized with 120 3S40P capacitors as a 3S (series) connection. As described above, by reducing the withstand voltage of the capacitor, 100 or more capacitors can be reduced as compared with the conventional example.

In the conventional example, the external filter capacitor bank has a volume of about 0.276 m ³ and a weight of about 1.
Although the weight is 60 kg, a circuit to be added in this embodiment includes a rectifying element 15 in addition to the external filter capacitor bank 14.
GTO thyristor 16, voltage detector 17, resistor 18, 1
Approximately 0.117m ³ including 9 and weighs about 50kg
Becomes That is, the volume is about 2/5 and the weight is about 1/3 as compared with the conventional example, so that the size and the weight are significantly reduced.
Moreover, since the capacitors constituting the external filter capacitor bank 14 operate only at a low voltage, the life of the capacitors is longer than that of the conventional example, so that a general electrolytic capacitor can be used and the configuration can be made at a low cost.

Note that the present invention is not limited to the above-described embodiment. As a self-extinguishing type semiconductor device, a GTR (Giant Transistor) instead of a GTO thyristor and an IGBT (Insula
A tedGate Bipolar Transistor element can also be used.

Next, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

The embodiment shown in FIG. 3 is different from the conventional power converter shown in FIGS. 7 and 8 in that an external filter capacitor device 2 is connected in parallel with the filter capacitor 6.
5 is connected. The external filter capacitor device 25 includes a GTO thyristor 20, which is connected in series with the external filter capacitor bank 14 similar to the embodiment of FIG. A diode 21 as a rectifier connected in anti-parallel to the GTO thyristor 20, a current detector 22 for detecting a discharge current of an external filter capacitor bank 14 connected in series with the GTO thyristor 20, An abnormal rapid discharge detection circuit 23 that monitors a discharge current value detected by the detector 22 and sends a signal to turn off the GTO thyristor 20 when detecting that an overcurrent has been discharged from the external filter capacitor bank 14; Gate drive circuit 24 that receives signal and turns off GTO thyristor 20 Are al configuration.

Next, the operation of the electric vehicle power converter having the above configuration will be described.

The DC current collected from the pantograph 2 is
While charging the filter capacitor 6, the diode 2
1 also charges the external filter capacitor bank 14. The DC current collected from the pantograph 2, the discharge current from the filter capacitor 6, and the discharge current from the external filter capacitor bank 14 are supplied to the inverter circuit 7, and are converted into three-phase AC and output. During the operation of the inverter circuit 7, the external filter capacitor bank 14 is charged via the diode 21 and
The operation of discharging through the TO thyristor 20 is repeated.

In the electric vehicle power converter having the above-described configuration, the protection operation when the upper and lower arms of the inverter circuit 7 cause a short circuit accident, which has been a problem in the prior art, will be described. The overcurrent tries to flow into the inverter circuit 7 via the GTO thyristor 20, but the current detector 22 connected in series to the GTO thyristor 20 detects the overcurrent, and the abnormal rapid discharge detection circuit 23 detects the overcurrent. Is sent to the gate drive circuit 24 to turn off the GTO thyristor 20 and prevent the overcurrent from being discharged from the external filter capacitor bank 14 and flowing into the inverter circuit 7.

Next, the operation of the abnormal rapid discharge detection circuit 23 will be described in more detail with reference to FIG. 4. The discharge current value i of the external filter capacitor bank 14 detected by the current detector 22 is determined by two methods. , An abnormality is determined. One of them is a temporal change (di) of the discharge current value i.
/ Dt) is monitored, the discharge current value i is held for one sampling via the sampling and holding circuit (SH) 26, and the difference between the current value before one sampling and the current current value is subtracted through the subtraction circuit 27. The difference is compared with a reference value C1 by a comparator 28. If the difference is larger than the reference value C1, an "H" signal is output, and if it is smaller, an "L" signal is output. The other is a method of monitoring the magnitude of the discharge current value i.
Is compared with a reference value C2 by a comparator 29, and outputs an "H" signal if it is larger than the reference value C2, and outputs an "L" signal if it is smaller than the reference value C2. The output signals of these comparators 28 and 29 are passed to an OR gate 30. If this output is “H”, a GTO thyristor off signal is sent to the gate drive circuit 24. That is, if a value larger than the reference value C1 or C2 is indicated by any of the above methods, an "H" signal is output from the OR gate 30, the GTO thyristor 20 is turned off, and when a short circuit accident of the inverter circuit 7 occurs, This prevents overcurrent caused by rapid discharge from the external filter capacitor bank 14 from flowing into the inverter circuit 7.

As described above, the overcurrent is prevented from being released by the two methods because the upper and lower arms of the inverter circuit 7 are short-circuited and the occurrence of overcurrent from the external filter capacitor bank 14 is immediately detected, and the GTO is detected. This is for turning off the thyristor 20. It should be noted that the reference values C1 and C2 can be easily determined because there is a very large difference between the current value itself and the time change of the current between the normal state and the abnormal state where the upper and lower arms of the inverter circuit 7 are short-circuited. Can be determined.

As described above, in the power converter for an electric vehicle according to the second embodiment of the present invention, even when the upper and lower arms of the inverter circuit 7 are short-circuited, the excess voltage discharged from the external filter capacitor bank 14 can be obtained. Since the current is detected and the GTO thyristor 20 is turned off by the operation of the abnormal rapid discharge detection circuit 23 and the gate drive circuit 24, the overcurrent is prevented from flowing through the inverter circuit 7, and the destruction of the switching element of the inverter circuit 7 is minimized. You can stop it as hard as possible.

Next, based on FIG. 5 and FIG.
Examples of the described invention will be described.

The embodiment shown in FIG. 5 is a combination of the embodiment of the invention described in claim 1 shown in FIG. 1 and the embodiment of the invention described in claim 2 shown in FIG. The difference from the conventional example shown in FIGS. 7 and 8 is that an external filter capacitor device 31 is connected in parallel with the filter capacitor 6.

This external filter capacitor device 31
1 has, as common elements to the embodiment of FIG. 1, an external filter capacitor bank 14 provided in parallel with the fill capacitor 6, a predetermined voltage at which the voltage across the filter capacitor 6 is lower than the rated voltage of 1500 V, For example, a rectifying element 15 that permits only the discharging of the external filter capacitor bank 14 when the voltage becomes 1100 V or less, a GTO thyristor 16 as a self-extinguishing rectifying element, and a voltage across the external filter capacitor bank 14 is constantly detected. A voltage detector 17 as a means for turning on the gate of the GTO thyristor 16 when the voltage falls below a predetermined set voltage, and a limiting resistor for limiting the current to each of the GTO thyristor 16 and the voltage detector 17. 1
8 and 19 are provided.

The voltage detector 17 turns off the voltage detection element 32 for detecting the voltage of the external filter capacitor bank 14, and turns off the GTO thyristor 16 when the voltage detection value of the voltage detection element 32 exceeds the comparison value. And an overhead wire voltage detection circuit 33 that outputs an on / off command signal to turn on the GTO thyristor 16 when the comparison value becomes equal to or less than the reference value, and performs on / off control of the GTO thyristor 16 based on the on / off command signal from the overhead wire voltage detection circuit 33. It comprises a gate drive circuit 34.

The external filter capacitor device 31 is connected in series with the external filter capacitor bank 14 in such a manner that the discharge direction of the external filter capacitor bank 14 is in the forward direction as a common element with the embodiment shown in FIG. A GTO thyristor 20 that is normally turned on and this G
A diode 21 as a rectifier connected in anti-parallel with the TO thyristor 20, a current detector 22 for detecting a discharge current of an external filter capacitor bank 14 connected in series with the GTO thyristor 20, and a current detector 22
An abnormal rapid discharge detection circuit 23 for monitoring the discharge current value detected by the above and sending a signal to turn off the GTO thyristor 20 when it is detected that the overcurrent is discharged from the external filter capacitor bank 14; G
Gate drive circuit 24 for turning off TO thyristor 20
It has.

Next, the operation of the electric vehicle power converter according to the third embodiment of the present invention will be described.

At the time of rating, while the overhead line voltage is detected by the voltage detecting element 32 of the voltage detector 17, the overhead line voltage detecting circuit 3
3 and the gate drive circuit 34 control the switching of the GTO thyristor 16 to apply a substantially constant voltage value (here, 1100 V) slightly higher than the low voltage protection voltage (here, 900 V) to the external disconnection filter capacitor bank 14. Charge).

The overhead line voltage detection circuit 3 of the voltage detector 17
The control function of No. 3 will be described with reference to the block diagram of FIG. 6. The overhead line voltage value v detected by the voltage detection element 32 is supplied to two comparators 35 and 36, where the reference value D 1 (here, 1100 V) is used. When the voltage value v is high, GT
An OFF signal of the O-thyristor 16 is output, and when the voltage value v is lower than the reference value D2 (here, 1100 V), GT
The ON signal of the O thyristor 16 is output, and the gate drive circuit 34 receives the ON / OFF signal to perform switching control of the GTO thyristor 16, and the external filter capacitor bank 14 is lower than the rated voltage 1500 V of the overhead wire or the third rail 1. The battery is charged and maintained at a substantially constant set voltage 1100V.

When the voltage detected by the voltage detecting element 32 is higher than 1100 V, no discharge is caused by the rectifying element 15 from the external filter capacitor bank 14 for disconnection, and the pantograph 2 is disconnected and the filter is disconnected. When the voltage of the capacitor 6 becomes 1100 V or less, the rectifying element 15 is turned on, and the power of the external filter capacitor bank 14 is supplied to the inverter circuit 7.
The change of the input voltage of the inverter circuit 7 at this time is shown in FIG.
It becomes what was shown in. In the third embodiment, the voltage applied to the external filter capacitor bank 14 is 1100 V at the maximum, as in the first embodiment shown in FIG. Then, 3S (series) connection is 3
It can be realized with 120 capacitors of S40P. As described above, by reducing the withstand voltage of the capacitor, 100 or more capacitors can be reduced as compared with the conventional example.

The external filter capacitor bank 1
4 is effective in extending the disconnection time of the pantograph 2, but at the same time, if an arm short circuit occurs in the inverter circuit 7, this external filter capacitor bank 14
Large current flows into the inverter circuit 7 and may damage even the peripheral circuit components. In order to prevent this, when a short-circuit accident of the upper and lower arms of the inverter circuit 7 occurs, the abnormal rapid discharge detection circuit 23 and The GTO thyristor 20 is cut off by the gate drive circuit 24.

That is, as described with reference to FIG. 4 as the operation of the second embodiment of the present invention, the overcurrent discharged from the external filter capacitor bank 14 is equal to GT.
An attempt is made to flow into the inverter circuit 7 via the O thyristor 20, but the current detector 22 connected in series to the GTO thyristor 20 detects an overcurrent, and the abnormal rapid discharge detection circuit 23 turns off the GTO thyristor 20. A signal is sent to the gate drive circuit 24 to turn off the GTO thyristor 20 and prevent the overcurrent released from the external filter capacitor bank 14 from flowing into the inverter circuit 7.

Thus, in the power converter for an electric vehicle according to the third embodiment of the present invention, the external filter capacitor device for extending the disconnection time of the pantograph can be made relatively small. In addition, when a short circuit accident occurs between the upper and lower arms of the inverter circuit, an overcurrent can be prevented from flowing into the switching element of the inverter circuit due to the presence of the external filter capacitor device.

In each of the above embodiments, the capacity and configuration of the external filter capacitor bank, the comparison reference value C1,
C2, D1, D2, etc. are not limited and can be changed as needed.

[0066]

As described above, according to the first aspect of the present invention, the inverter circuit can be operated continuously for a long time when the pantograph is disconnected, and the external filter capacitor bank is charged with a relatively low voltage. This allows the capacitor to be configured with a low withstand voltage due to the configuration of this capacitor bank, which enables downsizing,
Cost reduction can be achieved.

According to the second aspect of the present invention, when the switching element of the inverter circuit is destroyed and a short circuit occurs between the upper and lower arms, an excessive discharge current from the external filter capacitor bank suddenly increases. It is possible to prevent the element from flowing into the inside, and to minimize the element destruction in the event of a short circuit accident in the inverter circuit.

According to the third aspect of the present invention, the size and cost of the external filter capacitor bank can be reduced. An overcurrent can be reliably prevented from flowing into the inverter circuit from the attached filter capacitor bank, and element destruction can be minimized.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram according to an embodiment of the present invention.

FIG. 2 is a timing chart showing the operation of the embodiment.

FIG. 3 is a circuit block diagram of an embodiment of the invention according to claim 2;

FIG. 4 is a block diagram showing a control function of an abnormal rapid discharge detection circuit in the embodiment.

FIG. 5 is a circuit block diagram of an embodiment of the invention according to claim 3;

FIG. 6 is a block diagram showing a control function of the overhead wire voltage detection circuit in the embodiment.

FIG. 7 is a circuit block diagram of a conventional example.

FIG. 8 is a circuit block diagram of another conventional example.

FIG. 9 is a timing chart showing the operation of the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Overhead wire or 3rd rail 2 Pantograph 6 Filter capacitor 7 Inverter circuit 14 External filter capacitor bank 15 Rectifier 16 GTO thyristor 17 Voltage detector 20 GTO thyristor 21 Diode 22 Current detector 23 Abnormal rapid discharge detection circuit 24 Gate drive circuit 25 External filter capacitor device 32 Voltage detection element 33 Overhead wire voltage detection circuit 34 Gate drive circuit

Continuation of the front page (56) References JP-A-60-148301 (JP, A) JP-A-63-257401 (JP, A) JP-A-63-209404 (JP, A) JP-A-61-69307 (JP) , A) JP-A-2-74153 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60L 1/00-15/42

Claims (3)

(57) [Claims] 1. An electric vehicle which receives DC power from an overhead wire or a third rail via a pantograph, supplies the DC power to an inverter circuit connected in parallel to the inverter circuit via a filter capacitor, and converts DC / AC power into various loads of an electric vehicle. A power converter for an electric vehicle, which supplies a self-extinguishing type semiconductor element in parallel with the filter capacitor, and an external filter capacitor bank including a plurality of capacitors charged through the self-extinguishing type semiconductor element. A rectifying element for permitting only discharge from the external filter capacitor bank to the DC input side of the inverter circuit, and a voltage across the external filter capacitor bank, and detecting the voltage across the external filter capacitor bank as the input DC voltage of the inverter circuit. ON / OFF of the self-extinguishing type semiconductor element so as to maintain a predetermined set voltage lower than the rated value of Power conversion apparatus for an electric vehicle comprising a means for controlling the work. 2. Loads of DC power from an overhead wire or a third rail via a pantograph, supplied to an inverter circuit connected in parallel to the power supply via a filter capacitor, and converted into DC / AC power to load various electric vehicles. An electric vehicle power converter, which is connected in parallel to the filter capacitor and has an external filter capacitor bank consisting of a plurality of capacitors for supplying DC power to the inverter circuit even during instantaneous disconnection of the pantograph. Means for detecting a discharge current value from the external filter capacitor bank and electrically disconnecting the inverter circuit and the external filter capacitor bank when an arm short circuit occurs in the inverter circuit. Power converter. 3. Loads of DC power from an overhead wire or a third rail via a pantograph, supplied to an inverter circuit connected in parallel thereto through a filter capacitor, and converted into DC / AC power to load various loads on an electric vehicle. A power converter for an electric vehicle, which supplies a self-extinguishing type semiconductor element in parallel with the filter capacitor, and an external filter capacitor bank including a plurality of capacitors charged through the self-extinguishing type semiconductor element. A rectifying element for permitting only discharge from the external filter capacitor bank to the DC input side of the inverter circuit, and a voltage across the external filter capacitor bank, and detecting the voltage across the external filter capacitor bank as the input DC voltage of the inverter circuit. ON / OFF of the self-extinguishing type semiconductor element so as to maintain a predetermined set voltage lower than the rated value of Means for controlling the operation and means for detecting a discharge current value from the external filter capacitor bank and electrically disconnecting the inverter circuit and the external filter capacitor bank when an arm short circuit occurs in the inverter circuit. An electric vehicle power conversion device comprising: