JP2014075938A - Electric power converter for electric motor vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power converter for electric motor vehicles capable of detecting an anomaly of a discharge resistor arranged to discharge an electric charge of a filter capacitor and reducing the risk of hazards related to the anomaly.SOLUTION: An electric power converter 100 for electric motor vehicles includes: an inverter 8 converting power from an overhead power line 1 to power to be supplied to a load; a filter capacitor 6 connected in parallel to the input terminal of the inverter; at least one discharge resistor 5 connected in parallel to the filter capacitor; and a controller 50 determining presence and absence of an anomaly of the discharge resistor on the basis of voltages at both ends of the filter capacitor after a lapse of a specified time from cut-off of power from the overhead power line.

Description

Embodiments described herein relate generally to an electric vehicle power converter.

  An auxiliary power supply (SIV), which is a power conversion device for electric vehicles, is a facility that supplies power to lighting equipment, air conditioners, various control devices, and the like mounted on electric vehicles.

  Such an electric vehicle power converter is provided with a safety device so that the safety of the electric vehicle can be ensured even when an abnormality occurs in the facility, and a personal accident such as an electric shock does not occur. For example, a discharge resistor is known that is connected in parallel to a filter capacitor provided in a preceding stage of an inverter that constitutes an electric vehicle power converter (see, for example, Patent Document 1).

JP 2005-27499 A

  By the way, in the conventional system, only one system of discharge resistor is provided. Therefore, when the discharge resistor is broken, it is impossible to discharge the electric charge accumulated in the filter capacitor. Therefore, the risk of causing a disaster increases, which is not preferable for safety.

  Therefore, by providing a plurality of discharge resistors, even if one system is broken, it is possible to discharge in the remaining system and improve safety. However, even if it is configured to be able to discharge in the remaining system, the user recognizes the failure only when the disconnection failure occurs in the entire system.

  The present invention has been made in view of such circumstances, and detects an abnormality of a discharge resistor provided for discharging the charge of a filter capacitor, and reduces the risk of a disaster associated with the abnormality. An object of the present invention is to provide a power converter for an electric vehicle that can be used.

  According to an embodiment of the present invention for solving the above problem, in an electric vehicle power conversion device including an inverter that converts electric power from an overhead wire into electric power to be supplied to a load, the inverter is connected in parallel to an input terminal of the inverter A filter capacitor connected to the filter capacitor, at least one discharge resistor connected in parallel with the filter capacitor, based on the voltage across the filter capacitor when a predetermined time elapses after power from the overhead line is cut off, There is provided a power conversion device for an electric vehicle having a control device that determines whether or not a discharge resistor is abnormal.

The figure which shows the structure of the power converter device for electric vehicles of 1st Embodiment. The schematic diagram for demonstrating the discharge state of the filter capacitor in the electric power converter for electric vehicles of 1st Embodiment. The figure which shows the logic circuit which judges the presence or absence of abnormality of the discharge resistor in 1st Embodiment. The figure which shows the logic circuit which judges the soundness of the discharge resistor in 2nd Embodiment. The figure which shows the logic circuit which instruct | indicates the forced drive of the inverter in 3rd Embodiment. The figure which shows the structure of the power converter device for electric vehicles of 4th Embodiment.

[First embodiment]
The first embodiment will be described in detail with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration of a power converter for an electric vehicle according to the first embodiment.

  DC power is taken into the electric vehicle power converter 100 from the overhead line (not shown) via the current collector 1. The electric vehicle power converter 100 converts the captured DC power into AC and supplies the AC power to the load 9. Here, the overhead wire supplies, for example, DC power with a DC voltage of 1500V. The current collector 1 is a pantograph, for example, which is in electrical contact with an overhead wire.

  The electric vehicle power conversion device 100 includes a main circuit 101 and a control device 50.

  The main circuit 101 is provided with a high-speed circuit breaker 2, a contactor 3, a filter reactor 4, discharge resistors 5a and 5b, a filter capacitor 6, a voltage detector (DCPT) 7, and an inverter 8.

  The high speed circuit breaker 2 detects an abnormal direct current at a high speed and interrupts the fault current. The contactor 3 cuts or connects an electrical path connecting the current collector 1 and the inverter 8. The filter reactor 4 is provided in series between the electrical paths connecting the current collector 1 and the inverter 8. The filter capacitor 6 is provided in parallel with the input terminal on the DC power side of the inverter 8. The filter reactor 4 and the filter capacitor 6 constitute a filter circuit for DC power input to the inverter 8. The voltage detector 7 detects a DC voltage supplied via the current collector 1.

  The inverter 8 converts the DC power supplied via the current collector 1 into AC power and outputs the AC power to the load 9. The inverter 8 is configured as, for example, a U-phase, V-phase, and W-phase three-phase inverter, and one phase includes a plurality of switching elements such as IGBTs connected in series between the positive terminal and the negative terminal of the inverter 8. It is the structure which was made. Since this configuration is publicly known, detailed operation thereof is omitted. Further, the negative terminal of the inverter 8 is connected to a rail (ground) via a wheel.

  The control device 50 controls the operation of the main circuit 101 in an integrated manner. The control device 50 includes a sequence control unit 50a and an inverter control unit 50b.

  The sequence control unit 50a is connected to the high-speed circuit breaker 2, the contactor 3, and the voltage detector 7, and acquires information from each. Therefore, the sequence control unit 50a controls the sequence operation of the main circuit 101 based on the information detected by each detector, information on the state of the devices constituting the main circuit 101, and the processing information to the inverter control unit 50b. Output.

  The inverter control unit 50b outputs a gate command to the switching element of the inverter 8 based on the input processing information to drive the inverter 8, and outputs the processing information to the sequence control unit 50a.

Next, the case where the charge of the filter capacitor 6 is discharged will be described.
The charge of the filter capacitor 6 is discharged when the power supply of the electric vehicle power converter 100 is stopped.

  For example, when an abnormality such as an overcurrent occurs in the electric vehicle power conversion device 100 and the contactor 3 is opened (opened), or the electric vehicle is brought into a maintenance shop for inspection or the like and is This is the case when a command for forcibly turning off the power is input and the contactor 3 is opened. In this case, the electric charge remaining in the inverter 8 is discharged through the CR circuit formed by the filter capacitor 6 and the discharge resistors 5a and 5b.

  FIG. 2 is a schematic diagram for explaining the discharge state of the filter capacitor in the electric vehicle power converter according to the first embodiment.

  The horizontal axis in FIG. 2 represents the elapsed time from the start of discharge, and the vertical axis represents the voltage across the filter capacitor 6 detected by the voltage detector 7 (hereinafter referred to as filter capacitor voltage). A curve A is a discharge curve when the discharge resistors 5a and 5b are both healthy. A curve B is a discharge curve when one of the discharge resistors 5a and 5b is disconnected and the remaining one is healthy. Since the discharge resistors 5a and 5b are respectively connected in parallel to the filter capacitor 6, the resistance value viewed from the filter capacitor 6 increases when one of the resistors is disconnected. As a result, the time constant of discharge increases and the speed of discharge decreases. A curve C is a discharge curve when all of the discharge resistors 5a and 5b are disconnected.

  Assuming that the filter capacitor voltage at the start of discharge (time T0) is Vi, the filter capacitor voltage Vt after the lapse of the predetermined time T1 is V1, V2, and V3 for the curves A to C, respectively. The discharge resistors 5a and 5b have the same resistance value.

Therefore, the soundness of the discharge resistor can be determined by examining the filter capacitor voltage after a predetermined time has elapsed after the start of discharge.
Here, if the filter capacitor voltage Vi at the start of discharge (time T0) is a constant value, the soundness of the discharge resistor is determined by directly comparing the filter capacitor voltage Vt after a predetermined time and the threshold value. be able to. For example, when the filter capacitor voltage Vt is smaller than a predetermined threshold (for example, V1), it is determined that the discharge resistor is not disconnected. When the filter capacitor voltage Vt is larger than the predetermined threshold value V1, it is determined that one or more discharge resistors are disconnected.

  However, when the filter capacitor voltage Vi at the start of discharge (time T0) varies rather than a constant value, the normalized value of the filter capacitor voltage (= filter capacitor voltage Vt / filter capacitor voltage Vi) is compared with a threshold value. Thus, the soundness of the discharge resistor can be determined. For example, when the filter capacitor voltage Vt / filter capacitor voltage Vi is smaller than a predetermined threshold value V1 / Vi, it is determined that the discharge resistor is not disconnected. When the filter capacitor voltage Vt / filter capacitor voltage Vi is larger than a predetermined threshold value V1 / Vi, it is determined that one or more discharge resistors are disconnected.

  Note that the discharge resistors 5a and 5b need not have the same value. Even when the resistance values are different, the resistance value synthesized in parallel is smaller than the single resistance value, and thus the above-described disconnection determination algorithm can be similarly applied. Furthermore, by setting different resistance values, it is possible to determine which discharge resistor is disconnected.

  FIG. 3 is a diagram illustrating a logic circuit that determines whether or not the discharge resistor is abnormal in the first embodiment. This circuit is a configuration example for detecting that any one of the discharge resistors 5a and 5b is disconnected. This circuit is provided in the control device 50.

  As described above, when the contactor 3 is opened (opened) or when a command to forcibly turn off the power is input, the discharge of the filter capacitor 6 is started and the discharge start signal 13 is “ Set to 1 ". This discharge start signal 13 is a status signal. The discharge start signal 13 is input to the delay element 14. The delay element 14 delays the discharge start signal 13 by a predetermined time and outputs it to the logic integrator 15.

  On the other hand, the filter capacitor voltage 10 detected by the voltage detector 7 and the disconnection detection threshold value 11 are compared by the comparator 12, and the result is output to the logic integrator 15. That is, when the filter capacitor voltage 10> the disconnection detection threshold 11, the comparator 12 outputs “1”, and when the filter capacitor voltage 10 ≦ the disconnection detection threshold 11, the comparator 12 outputs “0”.

  When both the two input signals are “1”, the logic integrator 15 outputs “1” to the discharge circuit disconnection detection signal 16 and outputs a signal indicating that the disconnection has occurred in the discharge circuit. Therefore, the discharge circuit disconnection detection signal 16 outputs a signal indicating that a disconnection has occurred in the discharge circuit when the filter capacitor voltage 10 after a predetermined time has elapsed from the start of discharge is greater than a certain threshold value.

  As described above, the ratio between the current filter capacitor voltage and the filter capacitor voltage at the start of discharge is obtained, the ratio is compared with a threshold value, and the result is output to the logic integrator 15. Also good.

  The discharge circuit disconnection detection signal 16 is reset to “0” as the discharge progresses with time, except when all the discharge resistors are disconnected. Therefore, in the subsequent processing circuit, it is necessary to appropriately convert the signal into a required form depending on the intended use, such as holding the state when the discharge circuit disconnection detection signal 16 becomes “1”.

  In addition, as the predetermined time for checking whether or not the discharge resistor is abnormal by the filter capacitor voltage, a time in seconds (for example, 3 to 5 seconds) can be set. This is because the stability (reliability) of the signal is reduced when the time is short (for example, 1/10 second order), and from the safety aspect when the time is long (for example, several tens of second order). It is because it is not preferable.

[Second Embodiment]
The second embodiment is different from the first embodiment in that an abnormality is determined using a plurality of disconnection detection thresholds. The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 4 is a diagram illustrating a logic circuit that determines the soundness of the discharge resistor according to the second embodiment. This circuit is provided in the control device 50.

  As described above, when the contactor 3 is opened (opened) or when a command to forcibly turn off the power is input, the discharge of the filter capacitor 6 is started and the discharge start signal 13 is “ Set to 1 ". This discharge start signal 13 is a status signal. The discharge start signal 13 is input to the delay element 14. The delay element 14 delays the discharge start signal 13 by a predetermined time and outputs it to the logic integrator 15.

  On the other hand, the filter capacitor voltage 10 detected by the voltage detector 7 and the disconnection detection threshold values 11a, 11b, and 11c are respectively compared in the comparators 12a, 12b, and 12c, and the results are output to the logic integrators 15a, 15b, and 15c, respectively. Is done. That is, when the filter capacitor voltage 10> the disconnection detection thresholds 11a, 11b, and 11c, the comparators 12a, 12b, and 12c output “1”, respectively, and the filter capacitor voltage 10 ≦ the disconnection detection thresholds 11a, 11b, and 11c. Respectively, the comparators 12a, 12b, and 12c output "0".

  When the two input signals are both “1”, the logic integrators 15a, 15b, 15c output “1” to the discharge circuit disconnection detection signals 16a, 16b, 16c, and the discharge circuit is disconnected. A signal representing is output. Accordingly, the discharge circuit disconnection detection signals 16a, 16b, and 16c are signals that indicate that the disconnection has occurred in the discharge circuit when the filter capacitor voltage 10 after a predetermined time has elapsed from the start of discharge is greater than a predetermined threshold value. Is output.

  As described above, the ratio between the current filter capacitor voltage and the filter capacitor voltage at the start of discharge is obtained, the ratio is compared with a threshold value, and the result is output to the logic integrator 15. Also good.

  By determining the filter capacitor voltage by comparing it with a plurality of threshold values, it is possible to determine whether the discharge resistor is abnormal in more detail. For example, when there is a possibility of disconnection in the discharge circuit, it can be determined that one discharge circuit is surely disconnected, or when it can be determined that one or more (two) discharge circuits are disconnected Can be detected. And according to the detection result, it is possible to take a plurality of measures such as simply notifying an alarm, stopping if it has occurred a plurality of times, and stopping immediately.

[Third embodiment]
The third embodiment is different from the first embodiment in that when an abnormality of the discharge resistor is detected, the inverter 8 is forcibly driven to discharge. The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  When both of the discharge resistors 5a and 5b in FIG. 2 are disconnected, the charge accumulated in the filter capacitor 6 cannot be discharged through the discharge resistors 5a and 5b. On the other hand, the inverter 8 can be used as a discharge means for the electric charge accumulated in the filter capacitor 6 by controlling the switching element so as to form a discharge path.

  FIG. 5 is a diagram illustrating a logic circuit that instructs the forced drive of the inverter according to the third embodiment. This circuit is provided in the control device 50.

  When receiving the discharge circuit disconnection detection signal 16d indicating that both of the discharge resistors 5a and 5b are disconnected, the instruction generator 20 generates a single shot signal 17 and outputs it as an inverter operation command 18. The control device 50 that has received the inverter operation command 18 continues the operation of the inverter 8. Here, the control device 50 continues the operation of the inverter 8 while the single shot signal 17 is on.

  The operation of the inverter at this time can be different from the inverter operation that supplies alternating current to the load. For example, the electrical connection between the inverter 8 and the load 9 is opened by a contactor (not shown), and the inverter 8 is operated. As a result, a discharge path can be secured, so that the charge accumulated in the filter capacitor 6 can be consumed. Alternatively, the electrical connection between the inverter 8 and the load 9 is left as it is, and the inverter 8 is operated by setting the command value of the output voltage of the inverter 8 to 0 volts. Even when the inverter 8 is operated with no load, a discharge path can be secured in the same manner, so that the charge accumulated in the filter capacitor 6 can be consumed.

  There may be various methods for discharging by operating the inverter 8. For example, since the power loss is caused by executing the normal inverter operation, the charge of the filter capacitor 6 can be discharged. Therefore, an appropriate method can be adopted for the operation of the inverter 8.

In addition, if the operation time of the inverter 8 is about 1 to 2 seconds, a required purpose can be achieved.
In addition, the control device 50 and other devices that control the above-described operation can be operated by a battery mounted on the electric vehicle even when power is not supplied to the electric vehicle power conversion device 100. .

[Fourth embodiment]
In the fourth embodiment, the forced drive when the abnormality of the discharge resistor is detected is applied to the power converter that feeds power from the AC overhead wire. The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 6 is a diagram illustrating a configuration of an electric vehicle power converter according to the fourth embodiment.

The electric vehicle power converter 100 according to the fourth embodiment newly includes a main transformer 30 and a converter 31.
The main transformer 30 steps down the voltage of the AC power extracted from the overhead line (not shown). The stepped-down AC power is supplied to the converter 31. The converter 31 is a rectifier that converts an input single-phase AC voltage into a DC voltage, and is configured as a full-wave rectifier in which switching elements for the converter are combined. The controller 50 directly drives the switching element for the converter, so that the rectification operation is performed.

  As described above, when the instruction generation unit 20 receives the discharge circuit disconnection detection signal 16d indicating that both of the discharge resistors 5a and 5b are disconnected, the instruction generation unit 20 generates the single shot signal 17 and outputs it as the operation command 19. The control device 50 that has received the operation command 19 continuously executes at least one operation of the inverter 8 and the converter 31. Here, the control device 50 continuously executes at least one of the operation of the inverter 8 and the converter 31 while the single shot signal 17 is on. When both the inverter 8 and the converter 31 are operated, it is possible to discharge more effectively than when only one of them is operated.

  In addition, since various methods can be adopted as described above for the operation for discharging the inverter 8 and the converter 31, the operation may be performed by an appropriate method.

  In each of the above embodiments, the power conversion device provided with two discharge resistors has been described as an example. However, the present invention is not limited to this embodiment, and one or more discharge resistors are provided. It is clear that the present invention can be applied to power converters.

[effect]
According to the present embodiment described above, the disconnection of the discharge resistor can be detected, so that the user can recognize the occurrence of an abnormality, reduce the occurrence of a disaster due to a failure, and ensure safety. it can.
Moreover, since the disconnection state of the discharge resistor can be detected at a plurality of levels, it is possible to flexibly cope with the abnormal situation.

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

  DESCRIPTION OF SYMBOLS 1 ... Current collector, 2 ... High speed circuit breaker, 3 ... Contactor, 4 ... Filter reactor, 5a. 5 ... Discharge resistor, 6 ... Filter capacitor, 7 ... Voltage detector, 8 ... Inverter, 9 ... Load, 10 ... Filter capacitor voltage, 11 ... Disconnection detection threshold, 30 ... Main transformer, 31 ... Converter, 50 ... Control DESCRIPTION OF SYMBOLS 100: Power converter for electric vehicles, 101 ... Main circuit.

Claims (6)

In an electric vehicle power converter including an inverter that converts power from an overhead line into power to be supplied to a load,
A filter capacitor connected in parallel to the input terminal of the inverter;
At least one discharge resistor connected in parallel with the filter capacitor;
And a control device that determines whether or not the discharge resistor is abnormal based on a voltage across the filter capacitor when a predetermined time has elapsed since the power from the overhead line was cut off.   2. The control device according to claim 1, wherein the control device determines that at least one of the discharge resistors is abnormal when a voltage across the filter capacitor is greater than a predetermined threshold when a predetermined time has elapsed since the interruption. Electric vehicle power converter.   The control device has at least one when a ratio between a voltage across the filter capacitor at the time when a predetermined time has elapsed from the cutoff and a voltage across the filter capacitor at the cutoff is greater than a predetermined threshold. The electric power converter for an electric vehicle according to claim 1, wherein the discharge resistor is determined to be abnormal.   4. The electric power converter for an electric vehicle according to claim 2, wherein the control device includes a plurality of the predetermined threshold values, and determines a plurality of abnormal states corresponding to the respective threshold values. 5.   The electric power converter for an electric vehicle according to any one of claims 1 to 4, wherein when the controller determines that all the discharge resistors are abnormal, the inverter is driven for a predetermined time. The electric vehicle power converter further includes a converter,
The said control apparatus drives the at least one of the said inverter and a converter for predetermined time, when it judges that all the said discharge resistors are abnormal, The electricity of any one of Claims 1 thru | or 4 Car power converter.

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