JPH0731001A - Power converter for ac electric vehicle and protective operation method therefor - Google Patents

Abstract

PURPOSE:To protect a machine against damage by a constitution wherein the voltage across a smoothing capacitor is detected and an overvoltage suppressing thyristor is fired when a predetermined comparison voltage is exceeded to consume power stored in the smoothing capacitor through a suppressing resistor whereas a contactor is opened when the detected voltage exceeds the comparison voltage during idling operation. CONSTITUTION:AC power collected by a current collector 1 is fed through a transformer 3 and a contactor 4-1. It is converted into DC power which is further inverted into three-phase AC power for driving an AC motor 13. When the voltage across a smoothing capacitor 11 is higher than the voltage of a first comparator 15-1, an overvoltage suppressing thyristor 10-1 is fired to consume power, stored in the smoothing capacitor 11, through an overvoltage suppressing resistor 9. When the detected voltage exceeds the voltage of a second comparator 15-2 during idling operation, the contactor 4-1 is released to stop the operation of a converter 5 and an inverter 12. Consequently, DC over voltage is prevented from intruding into DC circuit and the smoothing capacitor 11 is protected against overvoltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power conversion device for an AC electric vehicle having a converter and a protection operation method thereof.

[0002]

2. Description of the Related Art Conventionally, alternating current power is used as a power source, the alternating current power source is converted into direct current by a PWM converter, and this direct current is reconverted into alternating current power of a variable voltage variable frequency and supplied to an alternating current electric motor to drive an electric vehicle. As such a power conversion device for an AC electric vehicle, a structure shown in FIG. 4 is known. This conventional AC electric vehicle power converter includes a current collector 1, a vacuum contactor 2, a transformer 3, a contactor 4-1 and a contactor control circuit 4-2 for controlling the opening of the contactor 4-1. A pulse width modulation (PWM) converter 5 is provided. The PWM converter 5 includes a self-extinguishing element 6 such as a GTO and a freewheeling diode 7, and converts an AC input into a DC and outputs the DC.

The conventional power converter also includes a converter 5
DC voltage detector 8 for detecting the DC output voltage of, a series circuit of overvoltage suppressing resistor 9 and overvoltage suppressing thyristor 10-1, smoothing capacitor 11, and a constant voltage DC smoothed by this smoothing capacitor 11 as an input, and a variable voltage Inverter 12 for converting to alternating current of variable frequency, AC motor 13 driven by the AC output of this inverter 12
Is equipped with.

The conventional power converter further includes a converter / inverter controller 14 for controlling switching of the gates of the converter 5 and the inverter 12, and a DC voltage detector 8 constituting a protection circuit for suppressing DC overvoltage.
Is provided with a comparator 15 for comparing the detection voltage of the above-mentioned with a comparison voltage and a voltage setting device 16 for setting the comparison voltage of the comparator 15, and an overvoltage signal output by the comparator 15 when the detection voltage is larger than the comparison voltage is contacted. The controller control circuit 4-2, the thyristor firing circuit 10-2, and the converter inverter control device 14 are input.

In this conventional AC electric vehicle power converter, the converter 5 converts AC power into DC power during power running and supplies it to the inverter 12 via the smoothing capacitor 11, and during regenerative braking, the inverter 12 operates.
The DC power from the side is converted into AC power and regenerated to the overhead wire through the current collector 1. On the contrary, the inverter 12 is the converter 5 supplied through the smoothing capacitor 11 during the power running operation.
The DC power from is converted into AC power by variable voltage variable frequency control, drives the AC motor 13, and converts the AC power obtained by the AC motor 13 into DC power and supplies it to the converter 5 during regenerative braking operation. At this time, the converter inverter control device 14 controls the phase of the converter 5 so as to keep the voltage of the capacitor 11 constant on the basis of the operation command by a speed signal from a master controller or a speed detector (not shown). The phase of the inverter 12 is controlled so that the rotation speed and the torque of the AC motor 13 have values according to the operation command from the master controller.

The overvoltage suppressing thyristor 10-1 is
When the DC circuit voltage detected by the voltage detector 8 in the comparison by the comparator 15 exceeds the voltage value preset by the voltage setter 16, the ignition signal is received from the overvoltage suppressing thyristor ignition circuit 10-2. An overvoltage suppressing operation of arcing and discharging the electric charge stored in the smoothing capacitor 11 through the overvoltage suppressing resistor 9 and immediately lowering the DC circuit voltage is performed. At the same time, the comparator 1
The converter 5 and the inverter 12 are stopped by the overvoltage detection signal 5 and the contactor 4-1 is opened. Here, the voltage set value by the voltage setter 16 is the converter 5
The cutoff voltage value generated during the switching operation of the self-extinguishing element 6 used in the inverter 12 is set to a value that is less than or equal to the maximum rated value of the self-extinguishing element 6.

[0007]

However, such a conventional AC electric vehicle power converter has the following problems. In general, the contactor 4-1 is not opened if the DC circuit voltage value remains above a certain value during the power running operation when the power running or regenerative braking command is turned off by the master controller. This is the contactor 4-1 during repowering or regenerative braking.
Is charged, the smoothing capacitor 11 is charged, the converter 5 is operated, the inverter 12 is operated, and the AC motor 13 is driven. The converter 5 is charged after the contactor 4-1 is charged until the capacitor 11 is charged. This is because it is necessary to prevent the operation delay of the inverter 12 and reduce the number of operations of the contactor 4-1.

During the running operation in the state where the contactor 4-1 is not opened, the smoothing capacitor 11 of the DC circuit collects the AC overhead wire power from the current collector 1, the vacuum circuit breaker 2, the main transformer. 3, contactor 4-1, diode 7 in converter 5
By full-wave rectification via the power line, the voltage is charged up to the peak voltage value of the overhead wire voltage and the voltage value depending on the conversion ratio of the main transformer 3.

However, the voltage value of the AC overhead wire is always affected by the waveform distortion and harmonics caused by the PWM converter operation of another vehicle, and this is superimposed on the AC voltage sent from the substation, and the voltage rises momentarily. There are cases.

Therefore, in such a voltage rising state of the AC overhead wire, if the contactor 4-1 is not opened, the smoothing capacitor 11 is charged with the peak value of the AC voltage due to the overhead wire voltage distortion. When the voltage value exceeds the value set by the voltage setter 16, the overvoltage suppressing thyristor 10-1 is ignited to discharge the electric charge of the smoothing capacitor 11, and at the same time, the converter inverter controller 14 causes the contactor 4-. 1 is opened. However, due to the operational delay of the contactor 4-1 alone and the operational delay due to the control delay of the converter / inverter control device 14, approximately 10
During 0 ms, the overhead wire power is current collector 1, vacuum circuit breaker 2, transformer 3, contactor 4-1, diode 7, overvoltage suppressing resistor 9,
It will flow through the overvoltage suppressing thyristor 10-1.

However, since the resistance value of the overvoltage suppressing resistor 9 is generally as small as several Ω, this current continues to flow as an excessive current for the circuit elements, and the converter 5 and the transformer 3 exceed the protection level value due to the overvoltage. And
There was a problem that the device might be damaged.

The present invention has been made in view of the above conventional problems, and a power conversion device for an AC electric vehicle capable of reliably preventing damage to the equipment that occurs when a DC overvoltage occurs during a descent operation, and It is an object of the present invention to provide a protection operation method.

[0013]

According to another aspect of the present invention, there is provided a power converter for an AC electric vehicle, which supplies AC power collected by a current collector through a transformer and a contactor to convert the AC power into DC power. A converter device for conversion, a parallel connection to the output end of the converter device, and a smoothing capacitor, an overvoltage suppressing thyristor, and an overvoltage suppressing resistor.The voltage across the smoothing capacitor is detected by a voltage detector. A DC circuit that ignites the overvoltage suppressing thyristor when the voltage is larger than the first comparison voltage value and consumes power accumulated in the smoothing capacitor in the overvoltage suppressing resistor, is connected in parallel to the DC circuit, and is converted by the converter device. An inverter device for converting a DC power into a three-phase AC power to drive an AC motor, and a detection voltage of the voltage detector that is higher than a first comparison voltage value. Compared with the second comparison voltage value, protection that opens the contactor and stops the operation of the converter device and the inverter device when the detected voltage exceeds the second comparison voltage value while the electric vehicle is running. And an operating circuit.

According to a second aspect of the present invention, there is provided a power converter for an AC electric vehicle, which includes a converter for supplying the AC power collected by a current collector through a transformer and a contactor to convert the AC power into DC power. It is connected in parallel to the output terminal of the converter device and consists of a smoothing capacitor, an overvoltage suppressing thyristor and an overvoltage suppressing resistor. The voltage across the smoothing capacitor is detected by a voltage detector, and this detected voltage is higher than a predetermined comparison voltage value. Sometimes connected to the DC circuit in parallel with the DC circuit that ignites the overvoltage suppression thyristor and consumes the power stored in the smoothing capacitor in the overvoltage suppression resistor,
An inverter device that drives the AC motor by converting the DC power converted by the converter device into three-phase AC power, and the rate of change of the detection voltage of the voltage detector is calculated, and this rate of change is compared with a predetermined comparison voltage increase rate. In comparison with the above, a protective operation circuit is provided to open the contactor and stop the operation of the converter device and the inverter device when the rate of change exceeds the comparison voltage increase rate during the running of the electric vehicle. .

According to a third aspect of the present invention, there is provided a protection operation method for a power converter of an AC electric vehicle, wherein the AC power collected by a current collector is supplied through a transformer and a contactor to convert the AC power into DC power. The converter device is connected in parallel to the output terminal of the converter device, and includes a smoothing capacitor, an overvoltage suppressing thyristor, and an overvoltage suppressing resistor. The voltage across the smoothing capacitor is detected by a voltage detector. DC voltage which is connected in parallel to the DC circuit and which is connected in parallel to the DC circuit and which is converted by the converter device when the overvoltage suppression thyristor is fired when it is larger than the comparison voltage value of In a power conversion device for an AC electric vehicle, which comprises an inverter device for converting a three-phase AC power to drive an AC motor, The detection voltage of the output device is compared with a second comparison voltage value that is smaller than the first comparison voltage value, and the contactor is activated when the detection voltage exceeds the second comparison voltage value while the electric vehicle is running. It is opened to stop the operation of the converter device and the inverter device.

According to a fourth aspect of the present invention, there is provided a protection operation method for a power converter for an AC electric vehicle, wherein the AC power collected by a current collector is supplied through a transformer and a contactor to convert the AC power into DC power. The converter device is connected in parallel to the output end of the converter device, and is composed of a smoothing capacitor, an overvoltage suppressing thyristor, and an overvoltage suppressing resistor.The voltage across the smoothing capacitor is detected by a voltage detector, and this detected voltage is a predetermined comparison voltage. A DC circuit that fires an overvoltage suppressing thyristor when it is larger than the value and consumes the power accumulated in the smoothing capacitor in the overvoltage suppressing resistor, and the DC power that is connected in parallel with the DC circuit and converted by the converter device in three phases In the power conversion device for an AC electric vehicle, which comprises an inverter device for converting the AC power to drive an AC motor, the voltage detection The change rate of the detected voltage is calculated, this change rate is compared with a predetermined comparison voltage increase rate, and the contactor is opened when the change rate exceeds the comparison voltage increase rate during the running of the electric vehicle. The operation of the converter device and the inverter device is stopped.

[0017]

In the power conversion device for an AC electric vehicle according to the present invention, in the converter device, the AC power collected by the current collector is supplied through the transformer and the contactor to convert the AC power into DC power. In the inverter device, the DC power converted by the converter device is converted into three-phase AC power to drive the AC motor.

In the DC circuit connected in parallel to the output terminal of the converter device, when the voltage across the smoothing capacitor detected by the voltage detector is larger than the predetermined first comparison voltage value, the overvoltage suppressing thyristor is turned on. The power that is ignited and stored in the smoothing capacitor is consumed in the overvoltage suppressing resistor. Further, in the protection operation circuit, the detection voltage of the voltage detector is set to a second value smaller than the first comparison voltage value.
When the detected voltage exceeds the second comparison voltage value during the running of the electric vehicle, the contactor is opened to stop the operation of the converter device and the inverter device. Prevents the DC capacitor from flowing and protects the smoothing capacitor from overvoltage.

According to a second aspect of the present invention, in the power converter for an AC electric vehicle, the converter device supplies the AC power collected by the current collector through the transformer and the contactor to convert the AC power into DC power. In the inverter device, the DC power converted by the converter device is converted into three-phase AC power to drive the AC motor.

Then, in the series circuit connected in parallel to the output end of the converter device, when the voltage across the smoothing capacitor detected by the voltage detector is larger than the predetermined comparison voltage value, the overvoltage suppressing thyristor is ignited. The power accumulated in the smoothing capacitor is consumed in the overvoltage suppressing resistor. Further, in the protection operation circuit, the rate of change of the detected voltage of the voltage detector is calculated, and this rate of change is compared with a predetermined comparison voltage increase rate, and the change rate determines the comparison voltage increase rate during the running of the electric vehicle. When it exceeds, the contactor is opened to stop the operation of the converter device and the inverter device, prevent the DC overvoltage from flowing into the DC circuit, and protect the smoothing capacitor from the overvoltage.

According to a third aspect of the present invention, there is provided a protection operation method for a power conversion device for an AC electric vehicle. In the power conversion device for an AC electric vehicle according to claim 1, the voltage detected by the voltage detector is based on a first comparison voltage value. Is smaller than the second comparison voltage value, and the contactor is opened to stop the operation of the converter device and the inverter device when the detected voltage exceeds the second comparison voltage value during the driving operation of the electric vehicle. This prevents the DC overvoltage from flowing to the DC circuit, and protects the smoothing capacitor from the overvoltage.

According to a fourth aspect of the present invention, there is provided a protection operation method for a power conversion device for an AC electric vehicle. In the power conversion device for an AC electric vehicle according to the second aspect, the rate of change in the voltage detected by the voltage detector is calculated, Compare the rate of change with a predetermined rate of comparison voltage rise,
When the rate of change exceeds the comparison voltage rise rate during the running of the electric vehicle, the contactor is opened to stop the operation of the converter device and the inverter device, thereby preventing DC overvoltage from flowing to the DC circuit. , Protect the smoothing capacitor from overvoltage.

[0023]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is an embodiment of the invention of claim 1 and shows a block diagram of a circuit implementing the method of the invention of claim 3. In the power converter for an AC electric vehicle according to this embodiment, parts common to the circuit elements of the conventional example shown in FIG. 4 are designated by the same reference numerals, and detailed description thereof will be omitted.

The characteristic of this embodiment is that the voltage setting device 16-1
In addition to the comparator 15-1 for comparing the set voltage set by the DC voltage detector 8 with the DC voltage detected by the DC voltage detector 8, the set voltage set by another voltage setter 16-2 is used for the DC voltage detector 8 Is provided with a comparator 15-2 for comparing with the DC voltage detected by, and further, a NOR gate 17 for a powering command and a regenerative braking command by a main controller (not shown), and an output of the comparator 15-2. The point is that a logical product gate 18 with the output of the NOR gate 17 is provided.

The set voltage value of the voltage setter 16-1 for giving the set voltage to the comparator 15-1 is the self-extinguishing like the GTO used in the converter 5 and the inverter 12 as the value of the DC circuit voltage. The voltage value applied when the current of the die element 6 is cut off does not exceed the maximum rated value of the self-extinguishing element 6, and the converter 5 and the inverter 12 are detected by an overhead line power failure detection when the overhead wire section enters during regenerative braking operation. Is set to a value that does not cause overvoltage detection even when the DC voltage rises due to the inductance existing in the main circuit during the control operation delay time of the operation stop.

The set voltage value of the voltage setter 16-2, which gives the set voltage to the comparator 15-2, is the voltage setter 16-1.
Is set to a value lower than the value set by, and set to a value higher than the DC voltage value that is constant-voltage controlled by converter inverter control device 14.

Next, the operation of the power conversion system for an AC electric vehicle having the above configuration will be described. The voltage value detected by the voltage detector 8 is input to the comparators 15-1 and 15-2. The conventionally used comparator 15-1 compares the value set by the voltage setter 16-1 with the DC voltage detected by the voltage detector 8 and newly added the comparator 1
5-2 compares the value set by the voltage setter 16-2 with the DC voltage detected by the voltage detector 8.

Therefore, when the detected DC voltage value detected by the voltage detector 8 becomes larger than the voltage set value set by the voltage setter 16-1, the comparator 15-1 causes the converter inverter controller 14 to convert the converter inverter. A stop command is output and at the same time the contactor control circuit 4-
2 to output a command to open the contactor 4-1 and further to output an overvoltage suppression thyristor 10-1 ignition command to the overvoltage suppression thyristor ignition circuit 10-2, thereby stopping the converter 5 and the inverter 12. At the same time, a protection operation is performed in which the overvoltage suppressing thyristor 10-1 is ignited to discharge the electric charge stored in the smoothing capacitor 11 through the overvoltage suppressing resistor.

Explaining the overvoltage protection operation during the drow running, neither the power running command nor the regenerative braking command is input during the drow running, so the output of the NOR gate 17 becomes "H". It is input to one of the AND gates 18. In this state, when the DC voltage detected by the voltage detector 8 becomes larger than the set voltage set by the voltage setter 16-2, the comparator 15-2 outputs an overvoltage detection signal and the AND gate 18 outputs The other input also becomes "H". As a result, the AND gate 18 outputs the "H" signal to the contactor control circuit 4-2, and the contactor control circuit 4
-2 opens the contactor 4-1 and stops the converter 5 and the inverter 12.

In this way, the contactor 4-1 is opened without igniting the overvoltage suppressing thyristor 10-1 against the voltage rise of the DC circuit caused by the voltage surge due to the disturbance of the overhead line voltage during the descent operation. Thus, the rise of the DC voltage is prevented, and the overcurrent of the converter 5 and the main transformer 3 due to the ignition of the overvoltage suppressing thyristor 10-1 is prevented.

Next, an embodiment of the invention of claim 2 and the invention of claim 4 will be described in detail with reference to FIG. FIG. 2 is an embodiment of the invention of claim 2 and is a block diagram of a circuit for implementing the method of the invention of claim 4, and the same reference numerals are used for the circuit elements common to the conventional example shown in FIG. The detailed description of the configuration will be omitted by adding.

The feature of the embodiment of the invention of claim 2 is that the comparator 15 in the embodiment of the invention of claim 1 shown in FIG.
-2 and the voltage setter 16-2, a differentiator 19 for obtaining the rate of change of the DC voltage detected by the DC voltage detector 8.
And a comparator 15-3 for comparing the rate of change of the DC voltage by the differentiator 19 with the set voltage increase rate, and this comparator 15-
Voltage rise rate setter 16 that gives the voltage rise rate set value to 3
It is a point equipped with 3. Further, similar to the embodiment of FIG. 1, a NOR gate 17 for detecting the running of the drive, and a logical product of the output of the NOR gate 17 and the output of the comparator 15-3. A gate 18 is provided.

Next, the operation of the embodiment of the invention of claim 2 will be described. The overvoltage protection operation of the DC circuit during the power running operation or the regenerative braking operation is the same as that of the first embodiment shown in FIG.

The overvoltage protection operation during the propulsion operation is performed as follows. That is, since the power running command and the regenerative braking command are not input during the running operation, the output of the NOR gate 17 becomes "H", and this is input to one of the AND gates 18. In this state, the DC voltage detected by the voltage detector 8 is first input to the differentiator 19, where the rate of change of voltage is obtained. Therefore, when the detected voltage change rate becomes larger than the voltage increase rate setting value set by the voltage increase rate setting unit 16-3, the comparator 15
-3 outputs an overvoltage detection signal, and the other input of the AND gate 18 also becomes "H". As a result, the AND gate 18
Outputs an "H" signal to the contactor control circuit 4-2, which opens the contactor 4-1 and stops the converter 5 and the inverter 12.

In this way, by detecting that the DC voltage of the DC circuit rapidly rises due to the voltage sudden rise due to the disturbance of the overhead line voltage during the descent operation, the contactor without firing the overvoltage suppressing thyristor 10-1. 4-1 is opened to prevent the DC voltage from rapidly increasing, and an overvoltage suppressing thyristor 10-1 is provided.
The overcurrent of the converter 5 and the main transformer 3 due to the ignition of is prevented beforehand.

Next, another embodiment of the invention of claim 2 and the invention of claim 4 will be described. FIG. 3 shows claim 2.
FIG. 4 is a block diagram of a circuit for implementing the method of the invention of claim 4 as another embodiment of the invention of FIG. 4, and in the embodiment shown in FIG. 3 as well, regarding circuit elements common to the conventional example shown in FIG. Are denoted by the same reference numerals, and detailed description of their configuration will be omitted.

The feature of the embodiment of the invention of claim 2 is that the same comparator 15-as that of the embodiment of the invention of claim 1 shown in FIG.
2 and a voltage setter 16-2, and a differentiator 19 for obtaining the rate of change of the DC voltage detected by the same DC voltage detector 8 as the embodiment of the invention of claim 2 shown in FIG. A comparator 15-3 for comparing the rate of change of the DC voltage by 19 with the set voltage increase rate, and a voltage increase rate setter 16-3 for giving the voltage increase rate set value to the comparator 15-3 are further provided. The point is that an OR gate 20 is provided to OR the outputs of the comparators 15-2 and 15-3. Also in FIG.
As in the embodiment shown in FIG. 2, a NOR gate 17 for detecting that the driver is driving is provided, and the NOR gate 17 is provided.
Output and the OR gate 20 of the comparators 15-2 and 15-3
And the output of the above are input to the logical product gate 18 to take the logical product of them, and the result of this logical product is input to the contactor control circuit 4-2.

Next, the operation of the embodiment of the invention of claim 2 having the above construction will be described. The overvoltage protection operation of the DC circuit during the power running operation or the regenerative braking operation is the same as that of the first embodiment shown in FIG. 1 or the second embodiment shown in FIG.

The overvoltage protection operation during the propulsion operation is performed as follows. That is, since the power running command and the regenerative braking command are not input during the running operation, the output of the NOR gate 17 becomes "H", and this is input to one of the AND gates 18.

In this state, when the DC voltage detected by the voltage detector 8 becomes larger than the set voltage set by the voltage setter 16-2, the comparator 15-2 outputs the overvoltage detection signal to the OR gate 20. Output to one side. At the same time, the DC voltage detected by the voltage detector 8 is also input to the differentiator 19, where the rate of change of voltage is obtained. Therefore, the rate of change in the detected voltage is set by the voltage rise rate setting unit 16
-3, the comparator 15-3 outputs an overvoltage detection signal to the other of the OR gates 20 when the voltage rise rate setting value becomes larger than the set value. So the OR gate 20
When an overvoltage detection signal is received from either the comparator 15-2 or the comparator 15-3, the "H" signal is output to the AND gate 1
8 will be input to the other side.

As a result, the AND gate 18 outputs the "H" signal from the NOR gate 17 indicating that the drive is running, and the "H" signal from the OR gate 20 indicating the overvoltage detection of the DC circuit.
Upon receiving the signal, the contactor control circuit 4-2 outputs an "H" signal, and the contactor control circuit 4-2 opens the contactor 4-1.
The converter 5 and the inverter 12 are stopped.

In this way, when the voltage suddenly rises due to the disturbance of the overhead line voltage during the running operation, the overvoltage suppressing thyristor 10 is detected by detecting the overvoltage of the predetermined value or more or the voltage increase rate of the predetermined value or more in the DC circuit.
The contactor 4-1 is opened without igniting -1 to prevent the DC voltage from rapidly rising, and the overcurrent of the converter 5 and the main transformer 3 due to the ignition of the overvoltage suppressing thyristor 10-1 is prevented.

[0043]

As described above, according to the device of the first aspect of the present invention, in the converter device, the AC power collected by the current collector is supplied through the transformer and the contactor to convert the AC power into DC power. In the inverter device, the DC power converted by the converter device is converted into three-phase AC power to drive the AC motor, and in the DC circuit connected in parallel to the output end of the converter device, by the voltage detector. The detected voltage across the smoothing capacitor is the first
When it is larger than the comparison voltage value of, the overvoltage suppression thyristor is ignited and the power accumulated in the smoothing capacitor is consumed in the overvoltage suppression resistor, and further in the protection operation circuit,
The detection voltage of the voltage detector is compared with a second comparison voltage value smaller than the first comparison voltage value, and contact is made when the detection voltage exceeds the second comparison voltage value during the running of the electric vehicle. Since the converter and inverter devices are stopped by opening the switch, the overvoltage suppression thyristor can be activated by detecting the overvoltage of the DC circuit due to the sudden rise in the voltage of the AC overhead line during the running operation. The contactor can be opened without arcing to prevent direct current overvoltage from flowing into the direct current circuit, and the relatively low rated smoothing capacitor can be protected from overvoltage during the propulsion operation.

According to the second aspect of the present invention, in the converter device, the AC power collected by the current collector is supplied through the transformer and the contactor to convert the AC power into DC power, and the inverter device is used. , The DC power converted by the converter device is converted into three-phase AC power to drive the AC motor, and both ends of the smoothing capacitor detected by the voltage detector in the series circuit connected in parallel to the output end of the converter device. When the voltage is higher than a predetermined comparison voltage value, the overvoltage suppressing thyristor is ignited and the power accumulated in the smoothing capacitor is consumed in the overvoltage suppressing resistor. Further, in the protection operation circuit, the rate of change of the detected voltage of the voltage detector is calculated, and this rate of change is compared with a predetermined comparison voltage increase rate, and the change rate determines the comparison voltage increase rate during the running of the electric vehicle. When it exceeds, the contactor is opened to stop the operation of the converter device and the inverter device.Therefore, it is necessary to detect the sudden rise of the voltage of the DC circuit due to the sudden rise of the voltage of the AC overhead line during the running operation. By this, it is possible to open the contactor without firing the overvoltage suppressing thyristor and prevent DC overvoltage from flowing to the DC circuit.
It is possible to protect a smoothing capacitor having a relatively low rating from overvoltage that occurs during the running operation.

According to the method of the third aspect of the present invention, the voltage across the smoothing capacitor detected by the voltage detector is compared with the second comparison voltage value which is smaller than the first comparison voltage value, and the electric running of the electric vehicle is performed. When the detected voltage exceeds the second comparison voltage value, the contactor is opened to stop the operation of the converter device and the inverter device. Therefore, the DC circuit caused by the sudden increase in the voltage of the AC overhead wire during the descent operation. By detecting the sudden rise of the voltage of, the contactor can be opened without igniting the overvoltage suppression thyristor, and it is possible to prevent the DC overvoltage from flowing into the DC circuit. The smoothing capacitor can be protected from the overvoltage generated during the uncontrolled running, and the series circuit can be assembled by using the circuit element having a relatively low breakdown voltage.

According to the method of the fourth aspect of the present invention, the rate of change of the voltage across the smoothing capacitor detected by the voltage detector is calculated, and this rate of change is compared with a predetermined comparison voltage increase rate to determine the electric vehicle. When the rate of change exceeds the comparison voltage increase rate during row operation, the contactor is opened to stop the operation of the converter and inverter devices.Therefore, the DC circuit caused by the sudden rise in the voltage of the AC overhead line during the row operation. By detecting the sudden rise of the voltage of, the contactor can be opened without igniting the overvoltage suppression thyristor, and it is possible to prevent the DC overvoltage from flowing into the DC circuit. The smoothing capacitor can be protected from the overvoltage generated during the uncontrolled running, and the series circuit can be assembled by using the circuit element having a relatively low breakdown voltage.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of an embodiment of the invention of claim 1;

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

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

FIG. 4 is a circuit block diagram of a conventional example.

[Explanation of symbols]

 1 Current Collector 2 Vacuum Contactor 3 Transformer 4-1 Contactor 4-2 Contactor Control Circuit 5 Converter 6 Self-extinguishing Type Element 7 Freewheeling Diode 8 Voltage Detector 9 Overvoltage Suppression Resistor 10-1 Overvoltage Suppression Thyristor 10 -2 Thyristor ignition circuit 11 Smoothing capacitor 12 Inverter 13 AC electric motor 14 Converter Inverter control device 15-1, 15-2, 15-3 Comparator 16-1 Voltage setting device 16-2 Voltage setting device 16-3 Voltage rise rate Setting device 17 NOR gate 18 Logical product gate 19 Differentiator 20 Logical OR gate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiko Ujiie No. 1 Toshiba-cho, Fuchu-shi, Tokyo Toshiba Corporation Fuchu factory

Claims (4)

[Claims] 1. A converter device for supplying alternating current power collected by a current collector through a transformer and a contactor to convert the alternating current power to direct current power, and a converter device connected in parallel to an output end of the converter device, A smoothing capacitor, an overvoltage suppressing thyristor, and an overvoltage suppressing resistor, the voltage across the smoothing capacitor is detected by a voltage detector, and the overvoltage suppressing thyristor is turned on when the detected voltage is larger than a predetermined first comparison voltage value. A DC circuit that arcs and consumes the electric power stored in the smoothing capacitor in the overvoltage suppressing resistor, and is connected in parallel to the DC circuit and converts the DC power converted by the converter device into three-phase AC power. An inverter device for driving an AC motor, and a second comparison voltage value in which the detection voltage of the voltage detector is smaller than the first comparison voltage value. And a protection operation circuit that opens the contactor and stops the operation of the converter device and the inverter device when the detected voltage exceeds the second comparison voltage value during the running operation of the electric vehicle. A power conversion device for an AC electric vehicle, comprising: 2. A converter device for supplying AC power collected by a current collector via a transformer and a contactor to convert the AC power to DC power, and a converter device connected in parallel to an output end of the converter device, It consists of a smoothing capacitor, an overvoltage suppressing thyristor and an overvoltage suppressing resistor, detects the voltage across the smoothing capacitor with a voltage detector, and ignites the overvoltage suppressing thyristor when the detected voltage is greater than a predetermined comparison voltage value. A DC circuit that consumes the electric power stored in the smoothing capacitor in the overvoltage suppressing resistor, and is connected in parallel to the DC circuit, and converts the DC power converted by the converter device into three-phase AC power to form an AC motor. The inverter device to be driven and the change rate of the detection voltage of the voltage detector are calculated, and the change rate is compared with a predetermined comparison voltage increase rate. And a protection operation circuit that opens the contactor and stops the operation of the converter device and the inverter device when the change rate exceeds the comparison voltage increase rate during the running of the electric vehicle. Power conversion device for AC electric vehicle. 3. A converter device for supplying alternating current power collected by a current collector through a transformer and a contactor to convert the alternating current power to direct current power, and a converter device connected in parallel to an output end of the converter device, A smoothing capacitor, an overvoltage suppressing thyristor, and an overvoltage suppressing resistor, the voltage across the smoothing capacitor is detected by a voltage detector, and the overvoltage suppressing thyristor is turned on when the detected voltage is larger than a predetermined first comparison voltage value. A DC circuit that arcs and consumes the power stored in the smoothing capacitor in the overvoltage suppressing resistor, and is connected in parallel to the DC circuit, and converts the DC power converted by the converter device into three-phase AC power. In a power conversion device for an AC electric vehicle comprising an inverter device for driving an AC electric motor, the detection voltage of the voltage detector is set to the first voltage. The second comparison voltage value which is smaller than the comparison voltage value, and the converter is opened by opening the contactor when the detected voltage exceeds the second comparison voltage value while the electric vehicle is running. A method for protecting and operating a power conversion device of an AC electric vehicle, comprising: stopping the operation of the device and the inverter device. 4. A converter device for supplying AC power collected by a current collector through a transformer and a contactor to convert the AC power into DC power, and a converter device connected in parallel to an output end of the converter device, It consists of a smoothing capacitor, an overvoltage suppressing thyristor and an overvoltage suppressing resistor, detects the voltage across the smoothing capacitor with a voltage detector, and ignites the overvoltage suppressing thyristor when the detected voltage is greater than a predetermined comparison voltage value. A DC circuit that consumes the power stored in the smoothing capacitor in the overvoltage suppressing resistor, and a DC circuit that is connected in parallel with the DC circuit and that converts the DC power converted by the converter device into three-phase AC power to form an AC motor. In a power conversion device for an AC electric vehicle, which comprises an inverter device for driving, a change rate of the detection voltage of the voltage detector is calculated. The change rate is compared with a predetermined comparison voltage increase rate, and the contactor is opened to open the contactor when the change rate exceeds the comparison voltage increase rate during the running of the electric vehicle. A protection operation method for a power conversion device of an AC electric vehicle, which comprises stopping the operation of an inverter device.