Vehicle auxiliary power supply

Abstract

A power conversion device (1) comprises a three-phase inverter (10) and a control device (12) for controlling the operation of the three-phase inverter (10). The three-phase inverter (10) converts input power to three-phase AC power and supplies the converted three-phase AC power to a load (4) via an AC output filter (2) equipped with an ACL (21) and ACC (22). The control device (12) estimates the capacitance of each phase of the ACC (22) on the basis of the information of three-phase voltages that are the voltages at the respective connection points (8a, 8b, 8c) between the ACL (21) and the ACC (22) and the information of three-phase first currents flowing between the three-phase inverter (10) and the respective connection points (8a, 8b, 8c).

Description

[Technical Field]

[0001] This disclosure relates to a power converter that converts input power into alternating current power and supplies it to a load, and to an auxiliary power supply device for a vehicle that includes the power converter and supplies power to a load mounted on a railway vehicle. [Background technology]

[0002] Conventional auxiliary power supply devices for vehicles include, for example, the one shown in Patent Document 1 below. In the auxiliary power supply device for vehicles described in Patent Document 1, a PWM (Pulse Width Modulation) converter is connected to the output terminal of a main transformer that transforms and outputs the AC input from the AC overhead line, and a three-phase inverter is connected to the output terminal of the PWM converter. Furthermore, an AC output filter is connected to the output terminal of the three-phase inverter to remove harmonic components contained in the output voltage of the three-phase inverter. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 4391339 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] In vehicle auxiliary power supply units, the AC output filter includes an AC filter capacitor. During maintenance of the vehicle auxiliary power supply unit, the AC filter capacitor is also inspected. During this inspection, the capacitance of the AC filter capacitor is measured. These measurements require removing the AC filter capacitor from the unit, which is a time-consuming process. To measure the capacitance of the AC filter capacitor without removing it, it is necessary to measure the current flowing through it. However, providing a dedicated current sensor for the AC filter capacitor would increase the number of components. Therefore, a method for measuring the capacitance of the AC filter capacitor without increasing the number of components was desired.

[0005] This disclosure has been made in view of the above, and aims to provide a power conversion device that can measure the capacitance of an AC filter capacitor without increasing the number of components. [Means for solving the problem]

[0006] To solve the above-mentioned problems and achieve the objective, the power conversion device according to this disclosure comprises a three-phase inverter and a control device for controlling the operation of the three-phase inverter. The three-phase inverter converts input power into three-phase AC power and supplies the converted three-phase AC power to the load via an AC output filter comprising an AC filter reactor and an AC filter capacitor. The control device includes a capacitance estimation unit that estimates the capacitance of each phase in the AC filter capacitor based on information of the three-phase voltage, which is the voltage at each connection point between the AC filter reactor and the AC filter capacitor, and information of the three-phase first current flowing between the three-phase inverter and each connection point. [Effects of the Invention]

[0007] The power conversion device described herein offers the advantage of being able to measure the capacitance of an AC filter capacitor without increasing the number of components. [Brief explanation of the drawing]

[0008] [Figure 1] Figure showing a configuration example of an auxiliary power supply device for a vehicle including a power conversion device according to Embodiment 1 [Figure 2] Figure showing a first configuration example of a power supply source for generating input power to the three-phase inverter shown in FIG. 1 [Figure 3] Figure showing a second configuration example of a power supply source for generating input power to the three-phase inverter shown in FIG. 1 [Figure 4] Functional block diagram showing a configuration example of a control device according to Embodiment 1 [Figure 5] Flowchart showing the process flow by the control device according to Embodiment 1 [Figure 6] Block diagram showing an example of a hardware configuration when the functions of the control unit according to Embodiment 1 are realized by software [Figure 7] Block diagram showing a configuration example when the functions of the control unit according to Embodiment 1 are realized by a control circuit [Figure 8] Figure showing a configuration example of an auxiliary power supply device for a vehicle including a power conversion device according to Embodiment 2

Embodiments for Carrying Out the Invention

[0009] Hereinafter, with reference to the accompanying drawings, the power conversion device and the auxiliary power supply device for a vehicle according to the embodiments of the present disclosure will be described in detail. Note that the embodiments described below are examples, and the scope of the present disclosure is not limited by the following embodiments. In addition, in the following embodiments, a power conversion device mounted on a railway vehicle is exemplified and described, but it is not intended to exclude application to other uses. Also, hereinafter, without distinguishing between electrical connection and physical connection, it will be simply referred to as "connection" for explanation. That is, the term "connection" includes both cases where components are directly connected to each other and cases where components are indirectly connected to each other via other components.

[0010] Embodiment 1. Figure 1 shows an example configuration of a vehicle auxiliary power supply device 100 including a power converter 1 according to Embodiment 1. As shown in Figure 1, the vehicle auxiliary power supply device 100 according to Embodiment 1 includes a power converter 1, an AC output filter 2, a voltage detection unit 14, and current detection units 15 and 16. The power converter 1 includes a three-phase inverter 10 and a control device 12. The three-phase inverter 10 and the load 4 are connected via the AC output filter 2 using three electrical wires 5. The three electrical wires 5 are "U-phase", "V-phase", and "W-phase" electrical wires. The load 4 is the target of power supply by the vehicle auxiliary power supply device 100. The load 4 is connected to the vehicle auxiliary power supply device 100 via an output contactor 3.

[0011] An example of load 4 is an auxiliary load. An auxiliary load is a term used to refer to loads other than the main motor that are installed on a railway vehicle. Examples of auxiliary loads include interior lighting equipment, door opening / closing devices, air conditioning equipment, safety equipment, compressors, batteries, and control power supplies. Of these auxiliary loads, the interior lighting equipment, door opening / closing devices, air conditioning equipment, safety equipment, and compressors are AC loads that operate on AC power. The battery and control power supply are DC loads that operate on DC power.

[0012] Returning to the explanation of Figure 1, the AC output filter 2 comprises an AC filter reactor (hereinafter referred to as "ACL" as appropriate) 21 and an AC filter capacitor (hereinafter referred to as "ACC" as appropriate) 22. The ACL 21 comprises three reactors. The ACC 22 comprises three capacitors. The three reactors in the ACL 21 are inserted into the corresponding U-phase, V-phase, or W-phase electrical wiring 5. One end of each of the three reactors is connected to the three-phase inverter 10. The other end of each of the three reactors is connected to the corresponding end of the capacitor in the ACC 22 at connection points 8a, 8b, and 8c in the electrical wiring 5. The other ends of the three capacitors are connected to each other at a single point. This connection is called a star connection. The connection point 7 of the star connection is grounded. The ACL 21 and ACC 22 constitute an LC AC output filter.

[0013] The voltage detection unit 14 detects the three-phase voltage v, which is the voltage at the connection points 8a, 8b, and 8c between the ACL 21 and the ACC 22. The current detection unit 15 detects the three-phase current i flowing between the three-phase inverter 10 and the connection points 8a, 8b, and 8c L , a and the current detection unit 16 detects the three-phase current i L flowing between the connection points 8a, 8b, and 8c and the load 4. In this article, the three-phase current i a is described as the "first three-phase current", and the three-phase current i L may be described as the "second three-phase current". Also, in this article, the current detection unit 15 may be described as the "first current detection unit", and the current detection unit 16 may be described as the "second current detection unit".

[0014] As will be described later, the capacitor current i c is calculated based on the three-phase current i a and the three-phase current i L . The capacitor current i c is the current flowing through the capacitors of each phase of the ACC 22. The three-phase current i a , the three-phase current i L and the capacitor current i c are positive in the direction of the arrows shown in the figure.

[0015] The voltage detection unit 14 and the current detection units 15 and 16 are sensors provided for controlling the three-phase inverter 10, and are not newly provided sensors for solving the problems of the power conversion device 1 and the vehicle auxiliary power supply device 100 according to the present disclosure. In the power conversion device 1 and the vehicle auxiliary power supply device 100 according to the present disclosure, the following control and calculations are performed using the detection values of these sensors.

[0016] In Figure 1, the voltage detection unit 14 is shown to detect the voltages at connection points 8a, 8b, and 8c, but it is not limited to this. The voltage detection unit 14 may also detect the voltage at a point shifted toward the ACL 21 side from the illustrated connection points 8a, 8b, and 8c. Furthermore, the voltage detection unit 14 may also detect the voltage at a point between connection points 8a, 8b, and 8c and the output contactor 3, shifted toward the load 4 side from connection points 8a, 8b, and 8c. In other words, the voltage detection unit 14 may detect the voltage at any point that is considered to be at the same potential as the potential of each connection point.

[0017] The three-phase inverter 10 converts input power into three-phase AC power under the control of the control device 12, and supplies the converted three-phase AC power to the load 4 via the AC output filter 2. The AC output filter 2 reduces harmonics contained in the output voltage of the three-phase inverter 10. As a result, a more sinusoidal AC voltage is applied to the load 4 compared to when the AC output filter 2 is not present.

[0018] Figure 2 shows a first configuration example of a power supply source that generates input power to the three-phase inverter 10 shown in Figure 1. In the first configuration example shown in Figure 2, DC power supplied from the DC overhead line 30 is received via the current collector 31. The received DC power is converted to AC power by the single-phase inverter 50. The converted AC power is stepped down by the transformer 52 and supplied to the single-phase converter 61. The stepped-down AC power is converted back to DC power by the single-phase converter 61 and supplied to the three-phase inverter 10.

[0019] Figure 3 shows a second configuration example of the power supply source that generates input power to the three-phase inverter 10 shown in Figure 1. In the second configuration example shown in Figure 3, the DC overhead line 30 is replaced with an AC overhead line 30A, and the current collector 31 for the DC overhead line is replaced with a current collector 31A for the AC overhead line. Comparing the configuration shown in Figure 3 with the configuration shown in Figure 2, in Figure 3, a transformer 41 and a single-phase converter 42 are provided between the current collector 31A and the single-phase inverter 50 in that order. The AC power supplied from the AC overhead line 30A is received by the transformer 41 via the current collector 31A. The received AC power is stepped down by the transformer 41 and supplied to the single-phase converter 42. The stepped-down AC power is converted to DC power by the single-phase converter 42 and supplied to the single-phase inverter 50. The subsequent operation is the same as in Figure 2. In Figures 2 and 3, the single-phase inverter 50, transformer 52, and single-phase converter 61, which are common components, are shown with the same reference numerals. However, it goes without saying that the capacity or type of each component will differ depending on the overhead line voltage.

[0020] Next, the configuration and operation of the control device 12 according to Embodiment 1 will be described. Figure 4 is a functional block diagram showing an example of the configuration of the control device 12 according to Embodiment 1. Figure 5 is a flowchart showing the processing flow by the control device 12 according to Embodiment 1. As shown in Figure 4, the control device 12 includes an ACC capacitance estimation unit 121 and an ACC degradation detection unit 122. The ACC capacitance estimation unit 121 calculates the estimated ACC capacitance, which is an estimated value of the capacitance of the capacitor in ACC22, according to the flowchart in Figure 5. The ACC degradation detection unit 122 also detects the degradation state of ACC22 according to the flowchart in Figure 5. The processing flow will be described below with reference to Figure 5. In the following description, it will be assumed that the vehicle auxiliary power supply device 100 is operating and the output contactor 3 is controlled to the "closed" state.

[0021] First, the ACC capacity estimation unit 121 calculates the three-phase current i a The instantaneous value and the three-phase current i L Based on the instantaneous value of , the capacitor current i is calculated by equation (1) below. cThe instantaneous value is calculated (step S11).

[0022] i c =i a -i L …(1)

[0023] Next, the ACC capacitance estimation unit 121 calculates the capacitor current i c The instantaneous value is converted to the RMS value (step S12). The ACC capacitance estimation unit 121 also determines the output frequency f from the instantaneous value of the three-phase voltage v (step S13). The output frequency f is the frequency of the fundamental wave included in the waveform of the instantaneous value of the three-phase voltage v.

[0024] The ACC capacitance estimation unit 121 uses the three-phase voltage v and the capacitor current i to estimate capacitance. c Based on the output frequency f, the estimated ACC capacitance is calculated using the following equation (2) (step S14).

[0025] ACC estimated capacity=√3×i c / (2πfv) …(2)

[0026] To determine the estimated capacitance of ACC, it is necessary to use the phase voltage applied across the capacitors of each phase and the phase current flowing through the capacitors of each phase. In the circuit configuration of Figure 1, ACC22 is connected in a star configuration, so the capacitor current i can be obtained using equation (1) above. c This represents the phase current. In the circuit configuration shown in Figure 1, the voltage detection unit 14 detects the line voltage. Therefore, the coefficient √3 is added to equation (2) above. Note that the calculations in equations (1) and (2) above are performed for each phase of UVW.

[0027] The information regarding the estimated ACC capacity for each phase obtained by equation (2) above is passed to the ACC degradation detection unit 122. The ACC degradation detection unit 122 compares the estimated ACC capacity for each phase with a determination threshold (step S15). All of the ACC22 no KoIf the estimated ACC capacitance of the capacitor is greater than the determination threshold (step S15, Yes), the ACC degradation detection unit 122 determines that the ACC 22 is not degraded (step S16). On the other hand, if the estimated ACC capacitance of at least one capacitor in the ACC 22 is less than or equal to the determination threshold (step S15, No), the ACC degradation detection unit 122 determines that the ACC 22 is degraded (step S17).

[0028] Figure 6 is a block diagram showing an example of a hardware configuration when the functions of the control device 12 according to Embodiment 1 are implemented in software. When the functions of the control device 12 according to Embodiment 1 are implemented in software, the configuration can include, as shown in Figure 6, a processor 200 that performs calculations, a memory 202 that stores and reads programs and threshold data read by the processor 200, an interface 204 that performs signal input and output, and a display 206 that displays the detection results.

[0029] The processor 200 is an example of a computing means such as an arithmetic unit, microprocessor, microcomputer, CPU (Central Processing Unit), or DSP (Digital Signal Processor). The memory 202 can be an example of non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable ROM), EEPROM (Registered Trademark) (Electrically EPROM), magnetic disks, flexible disks, optical disks, compact disks, minidiscs, or DVDs (Digital Versatile Discs).

[0030] The processor 200 can perform the above-described processing by exchanging necessary information via the interface 204, executing programs stored in memory 202, and referencing threshold data stored in memory 202. The calculation results from the processor 200 can be stored in memory 202. The processing results from the processor 200 can also be displayed on the display unit 206. Specifically, the display unit 206 displays the ACC estimated capacity and the determination results from the ACC degradation detection unit 122.

[0031] Figure 7 is a block diagram showing an example configuration when the functions of the control device 12 according to Embodiment 1 are implemented by a control circuit. In addition to the ACC capacitance estimation unit 121 and ACC degradation detection unit 122 shown in Figure 4, the control device 12 includes analog-to-digital (hereinafter referred to as "A / D") converters 120a, 120b, and 120c, and a frequency detection unit 120d.

[0032] The ACC capacity estimation unit 121 includes an adder / subtractor 121a, a low-pass filter (LPF) 121b, an RMS value calculation unit 121c, and an ACC estimated capacity calculation unit 121d. The ACC degradation detection unit 122 includes a comparator 122a.

[0033] The control device 12 receives a three-phase current i a The instantaneous value and the three-phase current i L The instantaneous value of and the instantaneous value of the three-phase voltage v are input. These instantaneous values ​​are converted into digital values ​​by A / D converters 120a, 120b, and 120c, respectively. For the sake of explanation, the same symbols will be used for digital values ​​as well, and the same names will be used without distinguishing between analog signals and digital values.

[0034] The outputs of A / D converters 120a and 120b are input to adder / subtractor 121a. The output of A / D converter 120c is input to ACC estimated capacitance calculation unit 121d and frequency detection unit 120d. The output of adder / subtractor 121a passes through low-pass filter 121b and is then input to RMS calculation unit 121c. The outputs of RMS calculation unit 121c and frequency detection unit 120d are input to ACC estimated capacitance calculation unit 121d.

[0035] The processing performed by the adder / subtractor 121a corresponds to the processing in step S11 of Figure 5. From the adder / subtractor 121a, the capacitor current i c The instantaneous value is output. The processing by the RMS calculation unit 121c corresponds to the processing in step S12 of Figure 5. The three-phase current i used in the calculation processing of step S11 a The instantaneous value contains many harmonics due to the switching operation of the three-phase inverter 10. Therefore, before the RMS value is calculated by the RMS value calculation unit 121c, a process is performed by the low-pass filter 121b to reduce the harmonics.

[0036] The processing by the frequency detection unit 120d corresponds to the processing in step S13 of Figure 5. As mentioned above, the three-phase current i a The instantaneous value of contains many harmonics, and consequently, the three-phase voltage v also contains harmonics. Therefore, it is desirable to perform filtering within the frequency detection unit 120d to reduce harmonics.

[0037] The processing by the ACC estimated capacity calculation unit 121d corresponds to the processing in step S14 of Figure 5. Furthermore, the processing by the comparator 122a in the ACC degradation detection unit 122 corresponds to the processing in steps S15 to S17 of Figure 5. The output of comparator 122a can be used as a degradation detection signal. 7In this embodiment, the ACC degradation detection unit 122 is configured with a single comparator 122a, but it is not limited to this configuration. The ACC degradation detection unit 122 may be composed of multiple comparators. By using multiple comparators and multiple judgment thresholds, the degree of degradation of the ACC 22 can be determined in multiple stages. This makes it possible to prompt the replacement of the AC output filter 2 before the AC output filter 2 fails. If the auxiliary power supply device 100 for vehicles according to Embodiment 1 is installed in a railway vehicle system, the decrease in the operating rate of the railway vehicle system can be suppressed.

[0038] As described above, according to Embodiment 1, the control device includes a capacitance estimation unit that estimates the capacitance of each phase in the AC filter capacitor based on information of the three-phase voltage, which is the voltage at each connection point between the AC filter reactor and the AC filter capacitor; information of the three-phase first current flowing between the three-phase inverter and each connection point; and information of the three-phase second current flowing between each connection point and the load. The information of the three-phase voltage, three-phase first current, and three-phase second current is detected by existing sensors. Therefore, there is no need to provide new sensors. This provides the effect of being able to measure the capacitance of the AC filter capacitor without increasing the number of components.

[0039] Furthermore, according to Embodiment 1, the capacitance estimation unit calculates the capacitor current flowing through each of the capacitors constituting the AC filter capacitor based on the three-phase first current and the three-phase second current when the output contactor is closed, and also calculates an estimated capacitance value based on the capacitor current, the three-phase voltage, and the output frequency of the three-phase voltage. This provides the effect of visualizing the degradation state of the AC filter capacitor.

[0040] Furthermore, in Embodiment 1, the control device includes a degradation detection unit that detects the degradation state of the AC filter capacitor based on the estimated capacitance value estimated by the capacitance estimation unit. This allows an alarm signal to be output to the worker or manager when the degradation of the AC filter capacitor progresses, thus facilitating equipment maintenance.

[0041] Embodiment 2. Figure 8 shows an example configuration of a vehicle auxiliary power supply unit 100A including a power converter 1 according to Embodiment 2. In Figure 8, compared to the configuration of the vehicle auxiliary power supply unit 100 shown in Figure 1, the AC output filter 2 is replaced with an AC output filter 2A, and a transformer 9 is inserted on the output side of the three-phase inverter 10. The AC output filter 2A has a delta-connected ACC24. The ACC24 is connected to the secondary side of the transformer 9. The primary winding of the transformer 9 is delta-connected, and the secondary winding of the transformer 9 is star-connected, with its neutral point being grounded. The other components are the same as or equivalent to the vehicle auxiliary power supply unit 100 shown in Figure 1, and the same or equivalent components are denoted by the same reference numerals, and redundant explanations are omitted.

[0042] Next, the configuration and operation of the control device 12 according to Embodiment 2 will be described. The basic operation is the same as in Embodiment 1, and only the differences will be described here.

[0043] The control device 12 according to Embodiment 2 controls the capacitor current i according to the following equation (3): c Calculate the instantaneous value of [the value].

[0044] i c =i a2 -i L …(3)

[0045] In equation (3) above, "i a2 " is the secondary current flowing on the secondary side of transformer 9. Secondary current i a2 This is detected by the current detection unit 15. The current detection unit 15 detects the primary current i flowing on the primary side of the transformer 9. a1 It may be configured to detect the secondary current i. a2 is the primary current i a1 The detected value can be obtained by converting it using the transformation ratio of transformer 9. Therefore, the three-phase first current referred to in this paper is the primary current i a1 and secondary current i a2 Any of these currents will suffice.

[0046] Furthermore, the control device 12 according to Embodiment 2 calculates the estimated ACC capacity using equation (3) above and equation (4) below.

[0047] ACC estimated capacity=(1 / √3)×i c / (2πfv) …(4)

[0048] As mentioned above, when determining the estimated capacitance of ACC, it is necessary to use the phase voltage at each phase capacitor and the phase current flowing through each phase capacitor. In the circuit configuration of Figure 8, ACC24 is delta connected, so the capacitor current i obtained by equation (3) above is i c This is the line current. Also, in the circuit configuration of Figure 8, the voltage detection unit 14 detects the line voltage. For this reason, the coefficient (1 / √3) is added to equation (4) above. Note that the calculations in equations (3) and (4) above are performed on each phase of UVW.

[0049] The determination and detection processes for the deterioration state of ACC24 are performed according to the flowchart in Figure 5. Alternatively, the determination and detection processes may be performed using the control circuit in Figure 7 instead of the flowchart in Figure 5.

[0050] As described above, according to Embodiment 2, the control device includes a capacitance estimation unit that estimates the capacitance of each phase in the AC filter capacitor based on information of the three-phase voltage, which is the voltage at each connection point between the AC filter reactor and the AC filter capacitor; information of the three-phase first current flowing between the three-phase inverter and the primary side of the transformer, or between the secondary side of the transformer and each connection point; and information of the three-phase second current flowing between each connection point and the load. The information of the three-phase voltage, three-phase first current, and three-phase second current is detected by existing sensors. Therefore, there is no need to provide new sensors. This provides the effect of being able to measure the capacitance of the AC filter capacitor without increasing the number of components.

[0051] Furthermore, according to Embodiment 2, the capacitance estimation unit calculates the capacitor current flowing through each of the capacitors constituting the AC filter capacitor based on the three-phase first current and the three-phase second current when the output contactor is closed, and also calculates an estimated capacitance value based on the capacitor current, the three-phase voltage, and the output frequency of the three-phase voltage. This provides the effect of visualizing the degradation state of the AC filter capacitor.

[0052] Furthermore, in Embodiment 2, the control device includes a degradation detection unit that detects the degradation state of the AC filter capacitor based on the estimated capacitance value estimated by the capacitance estimation unit. This allows an alarm signal to be output to the worker or manager when the degradation of the AC filter capacitor progresses, thus facilitating equipment maintenance.

[0053] Embodiment 3. Embodiments 1 and 2 described a method for calculating the estimated ACC capacity when the output contactor 3 is in the "closed" state. In contrast, Embodiment 3 describes a method for calculating the estimated ACC capacity when the output contactor 3 is in the "open" state.

[0054] The ACC capacity estimation unit 121 calculates the three-phase current i a Based on the instantaneous value, the capacitor current i is calculated using equation (5) below. c Calculate the instantaneous value of [the value].

[0055] i c =i a …(5)

[0056] Let's add some information to equation (5) above. Since the output contactor 3 is in the "open" state, no current flows to the load 4. Therefore, the three-phase current i L Since this also becomes zero, equation (5) above holds true.

[0057] The subsequent processing is the same as that for Embodiments 1 and 2. Therefore, in the case of Embodiment 1, i.e., the configuration shown in Figure 1, the estimated ACC capacitance is calculated based on equation (2) above. In the case of Embodiment 2, i.e., the configuration shown in Figure 8, the estimated ACC capacitance is calculated based on equation (4) above. Furthermore, the degradation state of the AC filter capacitor is detected based on the calculated estimated ACC capacitance.

[0058] Furthermore, the processing according to Embodiment 3 can be implemented in the vehicle's auxiliary power supply units 100 and 100A, positioned as a test mode or inspection mode. With this configuration, it becomes possible to continuously monitor the deterioration status of the AC filter capacitor through daily inspections, etc.

[0059] As described above, according to Embodiment 3, the control device includes a capacitance estimation unit that estimates the capacitance of each phase in the AC filter capacitor based on information of the three-phase voltage, which is the voltage at each connection point between the AC filter reactor and the AC filter capacitor, and information of the three-phase first current flowing between the three-phase inverter and each connection point. The information of the three-phase voltage and the three-phase first current is detected by existing sensors. Therefore, there is no need to provide new sensors. This provides the effect of being able to measure the capacitance of the AC filter capacitor without increasing the number of components.

[0060] Furthermore, according to Embodiment 3, the capacitance estimation unit calculates the capacitor current flowing through each phase capacitor constituting the AC filter capacitor based on the three-phase first current when the output contactor is open, and calculates an estimated capacitance value based on the capacitor current, the three-phase voltage, and the output frequency of the three-phase voltage. This provides the effect of visualizing the degradation state of the AC filter capacitor.

[0061] Furthermore, in Embodiment 3, the control device includes a degradation detection unit that detects the degradation state of the AC filter capacitor based on the estimated capacitance value estimated by the capacitance estimation unit. This allows an alarm signal to be output to the worker or manager when the degradation of the AC filter capacitor progresses, thus facilitating equipment maintenance.

[0062] Furthermore, the method of Embodiment 3 may be incorporated into a vehicle auxiliary power supply unit so that it can be implemented in a test mode or inspection mode. With a vehicle auxiliary power supply unit configured in this way, the deterioration state of the AC filter capacitor can be continuously monitored through daily inspections, etc.

[0063] The configurations shown in the above embodiments are merely examples, and it is possible to combine them with other known technologies, combine different embodiments, and omit or modify parts of the configuration without departing from the gist of the invention. [Explanation of symbols]

[0064] 1 Power converter, 2, 2A AC output filter, 3 Output contactor, 4 Load, 5 Electrical wiring, 7, 8a, 8b, 8c Connection point, 9, 41, 52 Transformer, 10 Three-phase inverter, 12 Control device, 14 Voltage detection unit, 15, 16 Current detection unit, 21 AC filter reactor, 22, 24 AC filter capacitor, 30 DC overhead line, 30A AC overhead line, 31, 31A Current collector, 42, 61 Single-phase converter, 50 Single-phase inverter, 100, 100A Auxiliary power supply for vehicles, 120a, 120b, 120c A / D converter, 120d Frequency detection unit, 121 ACC capacity estimation unit, 121a Adder / subtractor, 121b Low-pass filter, 121c RMS calculation unit, 121d ACC estimated capacity calculation unit, 122 ACC degradation detection unit, 122a comparator, 200 processor, 202 memory, 204 interface, 206 display.

Claims

1. A vehicle auxiliary power supply device comprising: a power converter mounted on a railway vehicle that uses DC or AC power supplied from an overhead line to supply three-phase AC power to an auxiliary load which is a load other than the main motor; and an AC output filter having an AC filter reactor connected to each output terminal of the power converter and an AC filter capacitor connected in a Y-shape at the load-side terminal of the AC filter reactor, The aforementioned power converter is A three-phase inverter that converts input power into three-phase AC power and supplies the converted three-phase AC power to the auxiliary load via the AC output filter, A control device for controlling the operation of the three-phase inverter, Equipped with, An output contactor is provided between the three-phase inverter and the auxiliary load. The control device includes a capacitance estimation unit that estimates the capacitance of each phase in the AC filter capacitor. The capacity estimation unit, When the output contactor is open, the estimated capacitance is calculated based on the three-phase voltage, which is the voltage at each connection point between the AC filter reactor and the AC filter capacitor, the three-phase first current flowing between the three-phase inverter and each connection point, and the output frequency of the three-phase voltage. When the output contactor is closed, the capacitor current flowing through each phase capacitor constituting the AC filter capacitor is calculated based on the three-phase first current and the three-phase second current flowing between each connection point and the auxiliary load, and the estimated capacitance is calculated based on the capacitor current, the three-phase voltage, and the output frequency of the three-phase voltage. A vehicle auxiliary power supply device characterized by the following features.

2. The capacitance estimation unit switches the calculation formula used to calculate the estimated capacitance depending on whether the output contactor is open or closed. The auxiliary power supply device for a vehicle according to feature 1.

3. When the output contactor is open, the capacity estimation unit determines the three-phase first current as i ａ Let v be the three-phase voltage and f be the output frequency, then √3 × i ａ The estimated capacitance is calculated using the formula / (2πfv), When the output contactor is closed, the capacitance estimation unit determines the capacitor current i ｃ Let v be the three-phase voltage and f be the output frequency, then √3 × i ｃ The estimated capacitance is calculated using the formula / (2πfv). The auxiliary power supply device for a vehicle according to feature 2.

4. A vehicle auxiliary power supply device comprising: a power converter mounted on a railway vehicle that uses DC or AC power supplied from an overhead line to supply three-phase AC power to an auxiliary load which is a load other than the main motor; a transformer having a primary winding delta-connected on the primary side and a secondary winding star-connected on the secondary side, with the primary winding connected to each output terminal of the power converter; and an AC output filter having an AC filter capacitor that is delta-connected and connected to each output terminal of the secondary winding of the transformer, The aforementioned power converter is A three-phase inverter that converts input power into three-phase AC power and supplies the converted three-phase AC power to the auxiliary load via the AC output filter, A control device for controlling the operation of the three-phase inverter, Equipped with, An output contactor is provided between the three-phase inverter and the auxiliary load. The control device includes a capacitance estimation unit that estimates the capacitance of each phase in the AC filter capacitor. The capacity estimation unit, When the output contactor is open, the estimated capacitance is calculated based on the line voltage, which is the voltage across each phase of the AC filter capacitor, the secondary current flowing through the secondary winding or the secondary current obtained by converting the primary current flowing through the primary winding using the transformer's transformation ratio, and the output frequency of the line voltage. When the output contactor is closed, the capacitor current flowing through each of the phase capacitors constituting the AC filter capacitor is calculated based on the secondary current and the three-phase second current flowing between each of the connection points between the secondary winding and the AC filter capacitor and the auxiliary load, and the estimated capacitance is calculated based on the capacitor current, the line voltage, and the output frequency of the line voltage. A vehicle auxiliary power supply device characterized by the following features.

5. The capacitance estimation unit switches the calculation formula used to calculate the estimated capacitance depending on whether the output contactor is open or closed. The auxiliary power supply device for a vehicle according to feature 4.

6. When the output contactor is open, the capacity estimation unit determines the secondary current as i ａ２ Let v be the line voltage and f be the output frequency, then (1 / √3) × i ａ２ The estimated capacitance is calculated using the formula / (2πfv), When the output contactor is closed, the capacitance estimation unit determines the capacitor current i ｃ Let v be the line voltage and f be the output frequency, then (1 / √3) × i ｃ The estimated capacitance is calculated using the formula / (2πfv). The auxiliary power supply device for a vehicle according to claim 5.

7. The vehicle auxiliary power supply device according to any one of claims 1 to 6, characterized in that the control device includes a degradation detection unit that detects the degradation state of the AC filter capacitor based on the estimated value of the capacitance estimated by the capacitance estimation unit.

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