JP2987814B2 - Startup protection method for 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 protection of an inverter having a configuration in which a plurality of inverters are fed in parallel by a set of power-on circuits, and more particularly to an inverter for controlling an induction motor for driving an electric vehicle and a stationary type. The present invention relates to a power converter protection method for an auxiliary power supply.

[0002]

2. Description of the Related Art With the development of self-extinguishing type power devices, electric devices for electric vehicles have been rapidly digitized, and their application to main circuits for driving, auxiliary power devices, and air conditioners has been rapid. In addition, there are many variations such as types of switching elements and circuit configurations.

For example, in a traveling apparatus using a combination of a VVVF (variable voltage variable frequency) inverter and an induction motor, one inverter can drive four or eight induction motors at a time, ), Individual units (one) and control units are subdivided according to the required quality of the vehicle system.

[0004] The circuit system is also a two-level inverter,
The switching element such as a three-level inverter is also GTO,
IGBTs, transistors, and the like, as well as various package forms of the elements, such as flat elements and module types, are available in various variations.

[0005] In such developments, subdivision of control units in the traveling apparatus has been spotlighted for the purpose of improving the redundancy system of the system. Also in the auxiliary power supply,
The shift to high-speed devices has begun due to improvements in low distortion and control response. On the other hand, due to the current capacity of the elements, there is a demand for splitting the power supply as well as parallel driving and subdivision of the control unit of the traveling device.

[0006] However, there is a limit to the range in which railway vehicles can be equipped with equipment. There is also a problem of cost increase. From this point, in consideration of the reliability of the device, it is common to use a single circuit for turning on / off the main power supply and connect a plurality of inverters in parallel at the subsequent stage.

[0007]

In such a configuration, there are the following three problems.

The first problem is that if one inverter is broken in the conduction mode, the input power supply system is short-circuited and an overcurrent flows, so that the main power supply cut-off circuit is turned off to protect it.
As a result, the main power supply of all the inverters connected to the circuit is turned off, so that all the inverters are stopped. Accordingly, the failure of the single system causes the entire system to stop, and the initial objective of the redundant system cannot be achieved.

A second problem is that since the inverter main circuits are connected in parallel, if one inverter is broken in the conduction mode, all the inverters are stopped to turn off the main circuit input circuit as described above. For this reason, since it is not possible to identify which inverter is broken, it is only possible to identify the faulty inverter by disconnecting each inverter one by one and restarting it by some means or restarting one inverter at a time and identifying the faulty inverter.

As a third problem, in the process of specifying the faulty inverter, the main power supply short-circuit mode occurs until the faulty inverter can be specified. If the substation equipment is weak in such a state, there is a possibility that an overhead line power outage will occur.

In order to eliminate the above-mentioned drawbacks of the prior art, the present invention provides a starting protection for a power converter in which a plurality of inverters driven in parallel can be started safely and a faulty inverter can be identified by one operation. The aim is to provide a method.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a power conversion apparatus configured to supply a plurality of inverters with DC main power in parallel by a set of main power-on circuits. A DC main power supply circuit having a current suppressing function, a gate circuit for sequentially outputting an operation test gate signal to switching elements constituting an inverter, an inverter input terminal voltage detector, and each inverter input current detector are provided. At the same time, an ON command is given to the DC main power-on circuit by a power converter start command, and at the same time, a command for generating an operation test gate signal is given to the gate circuit to make it conductive for testing, and the inverter input terminal voltage detector When the inverter input terminal voltage, which is the output of the inverter, is low, it is determined that the inverter component is defective in the short-circuit mode. A power converter protection circuit including a power converter start controller that identifies and stores which inverter is flowing current based on the output signal of the inverter input current detector, wherein the power converter start controller is When it is determined that the short-circuit mode is defective, the DC main power-on circuit is turned off, and the activation of the power converter is stopped.

The DC main power-on circuit has a current limiting function by inserting a starting resistor when starting the power converter. The power converter activation controller according to the present invention receives a signal for generating a test gate signal in the inverter gate circuit at the time of activation and an output signal from the inverter input voltage detector and the input voltage detector when the activation is completed, and performs a logic operation on the signals. The short circuit mode of the inverter component is identified and displayed by the product.

An inverter disconnection circuit is provided between each inverter and the DC main power supply circuit, and the operation of the circuit is controlled by the identification signal and the disconnection signal of the power converter start controller.

[0015]

With the above arrangement, the DC main power supply circuit is turned on while the current limiting function of the DC main power supply circuit is utilized when the power converter is started, and power is supplied to each inverter from the DC main power supply. The inverter gate circuit alternately supplies a gate signal from the power converter activation controller to the upper and lower element groups of each phase arm of the switching element.

When the switching element is short-circuited, the upper and lower arms are short-circuited, so that the inverter input terminal voltage is lower than the element ON voltage, and a current flows through the short-circuited arm. This short-circuit current flows only as limited by the current limiting function provided in the DC main power-on circuit. As a result, the input terminal voltages of all the inverters become very low as compared with the DC main power supply. The power converter activation controller receives the low voltage detection signal and determines which switching element of the inverter is in the short-circuit mode.

Also, the input current flows only to the faulty inverter in the short-circuit mode. The current detection signal is provided to the power converter activation controller to determine which inverter has failed. In this way, the output signals of the inverter input terminal voltage detectors and the inverter input current detectors
The power converter activation controller determines whether a short-circuit mode has occurred in the switching element and which inverter has failed.

When the voltage detector detects a low voltage, the DC main power supply circuit is turned off and the power converter is stopped. This prevents the DC power supply from unnecessarily causing the inverter to flow current. Also, when a low voltage is detected, the state of the current detector is identified to identify the inverter that has failed in the short-circuit mode.

The specified signal is stored, the logical product of the specified signal and the disconnection signal from the driver or another automatic device is taken, and the main circuit disconnection circuit of the established inverter is operated, so that the short-circuit mode inverter is operated. The power converter can be operated separately from the DC main power-on circuit, and the redundant system can be maintained.

If the low voltage detection of the voltage detector is not output at the completion of the start, the current limiting function of the DC main power-on circuit is eliminated, and at the same time, the gate circuit of the inverter is switched to the original operation mode of the inverter. And complete the startup by functioning as an inverter.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a power conversion apparatus starting protection method according to the present invention will be described below with reference to FIG. Fig. 1 shows an embodiment in which the startup protection method of the power converter according to the present invention is applied to an individual control VVVF device in which a DC overhead power source is a DC main power source and two VVVF inverters each drive one induction motor. FIG. Reference numeral 1 denotes a DC main power supply, which indicates a substation power supply. The pantograph 2 receives the DC main power from the overhead line, and the voltage type inverter 4
And 5, and the AC power converted by the voltage source inverter is supplied to the induction motors 7 and 8, respectively, to drive and brake the electric vehicle.

Reference numeral 6 denotes a start controller of the power converter, which receives a start command 6i from a driver's cab or the like, gives a turn-on command to the DC main power-on circuit 3 and a gate circuit 47.
And 57 are instructed to generate an operation test gate signal. Further, the timing for determining the short-circuit mode of the inverter components is determined, and the inverter input current detector 45 is determined.
And 55, and the detection signals of the inverter input terminal voltage detectors 43 and 53, the presence or absence of the short circuit mode of the inverter components is determined.

When the result of the judgment output is normal, an off command of the starting current suppressing function is output to the DC main power supply circuit 3, and the gate circuits 47 and 57 are used as inverters instead of operation test gate signals. Output a gate timing generation command.

When the result of the judgment output is the short-circuit mode, the inverter in which the current is flowing is stored from the detection signals of the inverter input current detectors 45 and 55, and an off command is sent to the DC main power supply circuit 3. And stop the VVVF device. When the start control circuit 6 receives the reset command 6R, it performs an AND operation with the stored signal of the current detector, and outputs the control coils 41a, 51a of the main circuit disconnecting circuits 41, 51 with its output.
To excite. That is, the control coil for which the logical product is established is turned on, the main circuit disconnecting circuit operates, and the faulty voltage type VVVF inverter is disconnected from the DC main power supply circuit 3.

Next, when the start command 6i is received, the start control by the above-described start protection method of the power converter is performed. Since the faulty inverter is disconnected as described above, the startup controller 6 outputs a normal determination signal and starts the operation of the VVVF device.

Next, each component of this embodiment will be described with reference to FIG. The main power supply circuit 3 is composed of a high-speed circuit breaker (HB) 31, a starting resistor 33, and a disconnector (LB) 32.
1. The disconnector 32 is operated by the respective closing coils 31a, 32a. Each device is turned on when each of the closing coils is turned on, and turned off when there is no excitation. The closing coil 31a,
32a is controlled by the logic output of the activation controller 6.

When the VVVF device is started, the line 62 is pressurized by applying a start command 6i to the start controller 6 to excite the high-speed circuit breaker closing coil 31a. As a result, the high-speed circuit breaker 31 is turned on. The current breaker 32 is excited after a predetermined time by a (on delay) delay circuit (timer 1) after the start command of the start controller 6 is pressurized. From the time the high-speed circuit breaker 31 is turned on to the time the current breaker 32 is turned on, the starting resistor 33 is inserted into the DC main power-on circuit.

When the start-up control is completed, the disconnector 32 is turned on, so that the start-up resistor 33 is short-circuited. The voltage type VVVF inverters 4 and 5 are connected to a DC main power supply circuit by main circuit disconnecting circuits 41 and 51, respectively. The main circuit disconnecting circuits 41 and 51 are normally closed circuits that are opened when the circuit exciting coils 41a and 51a are excited, and are controlled by the output of the activation controller 6.

Reference numerals 42 and 52 denote DC filter reactors and 44 and 54, respectively.
Is a filter capacitor. The L-type filter constitutes a filter for preventing harmonic components generated by the inverters 46 and 56 from flowing to the track circuit on the DC main power supply side.

The inverters 45 and 46 are two-level three-phase PWMs.
This is a three-phase inverter composed of six GTOs that outputs an alternating current, and is controlled by gate circuits 47 and 57. Regarding the snubber circuit and the PWM control of the gate circuit of the inverter,
The description is omitted because it does not directly relate to the present invention.

Next, when an activation test gate signal generation command is received from the activation controller 6 at the time of activation, the gate circuit 47,
The gate signal generated from 57 will be described. The gate signal for operation test is a method of sequentially giving the gate signal for on / off operation one by one to each GTO element, or the gate signal for on / off operation by grouping three upper and three lower gates in a bridge configuration. And so on.

The operation test gate signal may be given in any manner as long as current is not applied to the load. For example, when the operation test gate signal is supplied to the inverters 46 and 56 in each of the upper three and lower three groups of the bridge configuration, no arm short circuit occurs when all the GTOs are sound. As long as the current does not flow through the inverter, as long as at least one of the faults in the short-circuit mode exists, an arm short-circuit occurs when the sound element is turned on, and the DC input terminals of the inverters 46 and 56 are short-circuited.

Due to the short-circuit operation, the inverters 46 and 56 are connected to the high-speed circuit breaker 31, the starting resistor 33, the main circuit disconnecting circuits 41 and 51, and the DC filter reactors 42 and 52 of the DC main power supply circuit 3. 46, 56 arm short circuit,
A current flows through the current detectors 45 and 55 to the ground circuit of the DC main power supply. At the same time, filter capacitors 44,5
4 is also short-circuited by the arm short circuit of the inverters 46 and 56.

The gate circuits 47 and 57 continue to generate the aforementioned gate signals in order while receiving the operation test gate signal generation command from the activation controller 6. The gate circuits 47, 57
If there is no short circuit mode failure in each of the GTOs of the inverters 46 and 56 due to the gate signal of the inverters, no current flows to the inverters.
31, starting resistor 33, main circuit disconnecting circuits 41, 51, DC filter reactors 42, 52, filter capacitors 44, 54,
It continues to be charged by the circuit to the DC main power supply ground via the current detectors 45 and 55, and is charged to a high voltage proportional to the DC main power supply.

One of the Gs constituting the inverters 46 and 56
If the TO has a short-circuit mode defect, an arm short-circuit occurs when the paired healthy side element is turned on, and the filter capacitor charging current and the charge charged in the filter capacitor flow through the arm short-circuit circuit. 44, 54 remain low voltage.

Since the DC resistance of the DC filter reactors 42 and 52 is small and the cutoff frequency of the filter circuit is smaller than the frequency of the operation test gate signal generated by the gate circuits 47 and 57, the current detector A DC current of an average current having a value obtained by dividing the substantially DC main power supply voltage by the starting resistance value 33 flows through 44 and 55.

The voltage detector 43 detected by the above operation,
53 detection signals 43a, 53a and current detectors 45, 55 detection signals
45a and 55a are connected to the low-voltage comparators CP1 and CP2 of the activation controller 6.
And the current comparators CP3 and CP4.

Upon receiving the start command 6i, the start controller 6 controls the high-speed circuit breaker 31 and the gate circuits 47 and 57 of the DC main power supply circuit 3 as described above, and at the same time, (timer 1)>
The two delay circuits (timer 1) and (timer 2) having a time element of (timer 2) are started. Gate circuit 4
The operation test gate signal generation command given to 7, 57 continues to be given until (Timer 1) is turned on.

The delay circuit (timer 2) is turned on before the delay circuit (timer 1) is turned on. At the time when the timer 2 is turned on, the output signal of the timer 2 and the low voltage comparator are provided on condition that the contents of the storage devices (memory 2) and (memory 3) are not present.
Detection signals 43a and 53a of voltage detectors 43 and 53 via CP1 and CP2
Is obtained by the AND circuit AND1, and a storage device (memory 1) is set by the output.

When the storage device (memory 1) is turned on, the detection signals 45a and 55a of the current detectors 45 and 55 via the current comparators CP3 and CP4 and the output of the storage device (memory 1) are ANDed. The logical product is obtained by AND2 and AND3, and the result is set in the storage devices (memory 2) and (memory 3). When the storage devices (memory 2) and (memory 3) are established, the defective inverter display lamp 46a,
56a is lit.

When the storage device (memory 1) is set, the relay 6a is turned on, the b contacts 6a-b of the relay 6a are opened, and the coil 31 of the high-speed circuit breaker 31 of the DC main power supply circuit 3 is turned on.
a is turned off, the DC main power supply circuit 3 is turned off, and the VVVF inverter is stopped.

When the delay circuit (timer 2) is turned on and the detection signals 43a and 53a of the voltage detectors 43 and 53 are at a high voltage level, the AND circuit AND1 is not established, so the relay 6a is not turned on and startup protection is performed. Then, the timer 1 is turned on to turn on the exciting coil 32a of the disconnector 32 of the DC main power supply circuit 3, and the resistor 33 of the DC main power supply circuit 3 is short-circuited. At the same time, the linked auxiliary contacts 32a-b of the disconnector 32 are opened, so that the operation test gate signal generation command to the gate circuits 47 and 57 by the line 61 is turned off. This allows the gate circuit 4
Switches 7, 57 to PWM gate generation mode and operates as VVVF inverter. This operation completes the normal startup protection of the present invention.

On the other hand, when the VVVF device is stopped by the detection operation of the start protection according to the present invention, when a reset command 6R which is a command from a cab or a command for automatic restart by another mechanism is given, the reset command is issued. By the logical product of the signal and the output of the storage device (memory 2, memory 3),
The excitation coils 41a and 51a of the main circuit disconnecting circuit 41 or 51 are excited. By this excitation, the main circuit disconnecting circuit 41 or 51 on the side where the current has been flowing through the current detector is opened. This operation disconnects the inverter that is defective in the short-circuit mode.

The storage device (memory 1) is reset by the reset command 6R, and the relay 6a is turned off. When the start command 6i is given to the start controller 6 in this state, the VVVF inverter starts up normally again through the start protection mode. The AND circuits AND6 and AND7 of the start controller 6 detect a short circuit by the first start control, and the main circuit disconnecting circuit 41 or
When the power supply 51 is disconnected and restarted, the detection signal of the voltage detector on the disconnected side becomes zero, and the storage device (memory 1) is restored again.
Is a logic gate for preventing the operation of the circuit.

In the present embodiment, the DC main power supply circuit is implemented by a contact mechanism, but it may be digitized, and the starting resistor 33 is short-circuited by the disconnector 32. A circuit for disconnecting by a contactor or a disconnector may be replaced with an electronic switch.

The voltage detectors 43 and 53 are provided for each group.
The DC filter reactor 42, compared to the resistance of the starting resistor 33,
When the resistance value of 52 is small, only one set may be provided at the output terminal of the DC main power supply circuit 3.

Although the inverter current detectors 45 and 55 are provided on the ground line side, they may be connected to any position as long as the current of each group of inverters can be detected. The components used in the present embodiment are necessary elements for the VVVF inverter for individual control, except for some circuit elements of the startup controller 6 according to the present invention, and are particularly necessary for the present invention. There are no circuit elements.

[0048]

As described above, according to the present invention, the short-circuit mode detection of the inverters connected in parallel can be performed by changing the inverter start controller without providing any special equipment in the main circuit element. Not only can be detected without passing an excessive current through the inverter, but also the inverter on the defective side can be automatically detected, and the redundant system required for the system can be satisfied.

This effect not only increases as the number of parallel inverters increases, but also can be restored to normal by a minimum reset operation. In addition, it is easier and easier to find a defective inverter than when the present invention is not applied,
There are no substation trips and the effect is great.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a start-up protection method for a power converter according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC main power supply (substation power supply) 2 Pantograph 3 DC main power supply turning-on circuit 4,5 Voltage type inverter 6 Start-up control circuit of power converter 6i Start-up command 6R Reset command 7,8 Induction motor 31 High-speed circuit breaker (HB) 31a Close-up coil of high-speed circuit breaker 32 Breaker (LB) 32a Close-up coil of breaker 33 Start-up resistor 41, 51 Main circuit disconnection circuit 41a, 51a Main circuit disconnection circuit control coil 42, 52 DC filter reactor 43 , 53 Inverter input terminal voltage detector 44, 54 Filter capacitor 45, 55 Inverter input current detector 46, 56 Inverter 46a, 56a Faulty inverter indicator lamp 47, 57 Gate circuit 62 line CP1, CP2 Low voltage comparator CP3, CP4 Current Comparator 6a Relay 6a-b Contact b of relay 6a

Claims (2)

(57) [Claims] In a power converter configured to supply DC main power to a plurality of inverters in parallel by a set of main power supply circuits, a DC main power supply circuit having a start-up current suppressing function, and switching constituting an inverter. A gate circuit for sequentially outputting an operation test gate signal to the elements, an inverter input terminal voltage detector, and each inverter input current detector; and the DC main power supply circuit is turned on by a power converter start command. At the same time as giving the command, an instruction for generating an operation test gate signal is given to the gate circuit to make it conductive for testing, and if the inverter input terminal voltage output from the inverter input terminal voltage detector is low, the inverter At the same time that the component is determined to be defective in the short-circuit mode, which inverter is A power conversion device protection circuit including a power conversion device activation controller for discriminating and storing whether a current is flowing through the power converter. A start-up protection method for a power converter, comprising turning off a power-on circuit and stopping the start of the power converter. 2. The starting protection method for a power converter according to claim 1, wherein a disconnection circuit is provided in each inverter DC main power supply connection path, and when the short-circuit mode is detected by the power converter startup controller, the DC main power supply turning-on circuit is provided. After turning off, the disconnection circuit corresponding to a signal established by the logical product of the power converter reset command signal and the storage signal of the storage device storing which inverter is determined to be defective is turned off. A start-up protection method for a power converter.