POWER CONVERTER AND VEHICLE ASSISTANCE SUPPLY
Patent Information
- Application Number
- DE112022007439
- Authority / Receiving Office
- DE · DE
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2022-06-28
- Publication Date
- 2025-04-10
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
Power conversion device and vehicle auxiliary power supply device
[0001] The present disclosure relates to a power conversion device that converts input power into AC power and supplies it to a load, and to a vehicle auxiliary power supply device that includes the power conversion device and supplies power to a load mounted on a railway vehicle.
[0002] A conventional vehicle auxiliary power supply device is disclosed, for example, in Patent Document 1. In the vehicle auxiliary power supply device 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 AC input from an 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.
[0003] Patent No. 4391339
[0004] In a vehicle auxiliary power supply device, the AC output filter includes an AC filter capacitor. When performing maintenance on the vehicle auxiliary power supply device, the AC filter capacitor is also inspected. During this inspection, the capacitance of the AC filter capacitor is measured. These measurements require the AC filter capacitor to be removed from the device, 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 the AC filter capacitor. However, providing a current sensor dedicated to the AC filter capacitor increases 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] The present disclosure has been made in view of the above, and has an object to provide a power conversion device that can measure the capacitance of an AC filter capacitor without increasing the number of parts.
[0006] To solve the above-mentioned problems and achieve the object, a power conversion device according to the present disclosure includes a three-phase inverter and a control device that controls 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 a load via an AC output filter that includes an AC filter reactor and an AC filter capacitor. The control device includes a capacitance estimator that estimates the capacitance of each phase of the AC filter capacitor based on information on three-phase voltages that are voltages at each connection point between the AC filter reactor and the AC filter capacitor and information on a three-phase first current that flows between the three-phase inverter and each connection point.
[0007] The power conversion device according to the present disclosure has the advantage of being able to measure the capacitance of an AC filter capacitor without increasing the number of parts.
[0008] FIG. 1 is a diagram showing a configuration example of a vehicle auxiliary power supply device including a power conversion device according to a first embodiment. FIG. 2 is a diagram showing a first configuration example of a power supply source that generates input power to the three-phase inverter shown in FIG. 1. FIG. 3 is a diagram showing a second configuration example of a power supply source that generates input power to the three-phase inverter shown in FIG. 1.
[0009] A power conversion device and a vehicle auxiliary power supply device according to embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Note that the embodiments described below are merely examples, and the scope of the present disclosure is not limited to the following embodiments. In addition, although the following embodiments will be described using a power conversion device mounted on a railway vehicle as an example, this is not intended to exclude application to other uses. In addition, in the following description, electrical connection and physical connection will not be distinguished from each other, and will be simply referred to as "connection." In other words, 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] First Embodiment Fig. 1 is a diagram showing an example of the configuration of a vehicle auxiliary power supply device 100 including a power conversion device 1 according to a first embodiment. As shown in Fig. 1, the vehicle auxiliary power supply device 100 according to the first embodiment includes a power conversion device 1, an AC output filter 2, a voltage detection unit 14, and current detection units 15 and 16. The power conversion device 1 includes a three-phase inverter 10 and a control device 12. The three-phase inverter 10 and a load 4 are connected via the AC output filter 2 using three electrical wirings 5. The three electrical wirings 5 are for the "U phase," "V phase," and "W phase." The load 4 is a target to which power is supplied 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 installed on a railway vehicle other than the main motor. Examples of auxiliary loads are interior lighting devices, door opening / closing devices, air conditioning devices, safety equipment, compressors, batteries, and control power supplies. Of these auxiliary loads, the interior lighting devices, door opening / closing devices, air conditioning devices, safety equipment, and compressors are AC loads that operate by receiving AC power. The batteries and control power supplies are DC loads that operate by receiving DC power.
[0012] Returning to the description of FIG. 1 , the AC output filter 2 includes an AC filter reactor (hereinafter, appropriately referred to as "ACL") 21 and an AC filter capacitor (hereinafter, appropriately referred to as "ACC") 22. The ACL 21 includes three reactors. The ACC 22 includes three capacitors. The three reactors in the ACL 21 are inserted into the electrical wiring 5 of the corresponding U-phase, V-phase, or W-phase. 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 one end of a corresponding 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. Connection point 7, which is the connection point of the star connection, is grounded. The ACL 21 and the ACC 22 form an LC AC output filter.
[0013] The voltage detector 14 detects a 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 detector 15 detects a three-phase current i flowing between the three-phase inverter 10 and the connection points 8a, 8b, and 8c. ａ The current detection unit 16 detects the three-phase current i flowing between the connection points 8a, 8b, 8c and the load 4. Ｌ In this paper, the three-phase current i ａ is referred to as the "three-phase first current", and the three-phase current i Ｌ In this document, the current detection unit 15 may be referred to as a "first current detection unit" and the current detection unit 16 may be referred to as a "second current detection unit."
[0014] As will be described later, the capacitor current i ｃ is the three-phase current i ａ and three-phase current i Ｌ The capacitor current i ｃ is the current flowing through the capacitor of each phase of the ACC 22. ａ , three-phase current i Ｌ and the capacitor current i ｃ The direction of the arrow shown in the figure is positive.
[0015] The voltage detection unit 14 and the current detection units 15, 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. The power conversion device 1 and the vehicle auxiliary power supply device 100 according to the present disclosure perform the control and calculations described below using the detection values of these sensors.
[0016] 1, the voltage detection unit 14 is illustrated as detecting the voltages at the connection points 8a, 8b, and 8c, but this is not limiting. The voltage detection unit 14 may also detect the voltage at a point shifted toward the ACL 21 from the connection points 8a, 8b, and 8c shown in the figure. The voltage detection unit 14 may also detect the voltage at a point shifted toward the load 4 from the connection points 8a, 8b, and 8c between the connection points 8a, 8b, and 8c and the output contactor 3. In other words, the voltage detection unit 14 may detect the voltage at any location as long as the location is considered to have the same potential as the potential of each connection point.
[0017] Under the control of a control device 12, the three-phase inverter 10 converts input power into three-phase AC power and supplies the converted three-phase AC power to a load 4 via an 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, an AC voltage that is more sinusoidal than when the AC output filter 2 is not present is applied to the load 4.
[0018] Fig. 2 is a diagram showing a first configuration example of a power supply source that generates input power to the three-phase inverter 10 shown in Fig. 1. In the first configuration example shown in Fig. 2, DC power supplied from a DC overhead line 30 is received via a current collector 31. The received DC power is converted to AC power by a single-phase inverter 50. The converted AC power is stepped down by a transformer 52 and supplied to a 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] FIG. 3 is a diagram showing a second configuration example of a power supply source that generates input power to the three-phase inverter 10 shown in FIG. 1 . In the second configuration example shown in FIG. 3 , the DC overhead line 30 is replaced with an AC overhead line 30A, and the DC overhead line current collector 31 is replaced with an AC overhead line current collector 31A. Comparing the configuration shown in FIG. 3 with the configuration shown in FIG. 2 , a transformer 41 and a single-phase converter 42 are provided in this order between the current collector 31A and the single-phase inverter 50. 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 that shown in FIG. 2 . In addition, in Figures 2 and 3, the single-phase inverter 50, the transformer 52, and the single-phase converter 61, which are common components, are indicated by the same symbols, but 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 the first embodiment will be described. FIG. 4 is a functional block diagram showing an example configuration of the control device 12 according to the first embodiment. FIG. 5 is a flowchart showing the flow of processing by the control device 12 according to the first embodiment. As shown in FIG. 4, the control device 12 includes an ACC capacity estimation unit 121 and an ACC degradation detection unit 122. The ACC capacity estimation unit 121 calculates an estimated ACC capacity, which is an estimated value of the capacitance of the capacitor in the ACC 22, according to the flowchart in FIG. 5. The ACC degradation detection unit 122 also detects the degradation state of the ACC 22 according to the flowchart in FIG. 5. The processing flow will be described below with reference to FIG. 5. In the following description, it is 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 estimates the three-phase current i ａ and the instantaneous value of the three-phase current i Ｌ Based on the instantaneous value of ｃ The instantaneous value of is calculated (step S11).
[0022] i ｃ = i ａ -i Ｌ …(1)
[0023] Next, the ACC capacity estimation unit 121 calculates the capacitor current i ｃ The instantaneous value of the three-phase voltage v is converted into an effective value (step S12). The ACC capacity estimator 121 then calculates 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 capacity estimation unit 121 estimates the three-phase voltage v and the capacitor current i ｃ and the output frequency f, the estimated ACC capacity is calculated by the following equation (2) (step S14).
[0025] ACC estimated capacity=√3×i ｃ / (2πfv)...(2)
[0026] In addition, when calculating the estimated ACC capacity, it is necessary to use the phase voltage applied to both ends of the capacitor of each phase and the phase current flowing through the capacitor of each phase. In the circuit configuration of Figure 1, since the ACC 22 is star-connected, the capacitor current i ｃ is the phase current. In the circuit configuration of FIG. 1, the voltage detection unit 14 detects the line voltage. For this reason, a coefficient of √3 is added to the above equation (2). The calculation of the above equations (1) and (2) is performed for each of the UVW phases.
[0027] Information about the estimated ACC capacity for each phase calculated by the above formula (2) 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). If the estimated ACC capacity of at least one capacitor in the ACC 22 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 capacity of at least one capacitor in the ACC 22 is equal to or less than the determination threshold (step S15, No), the ACC degradation detection unit 122 determines that the ACC 22 is degraded (step S17).
[0028] Fig. 6 is a block diagram showing an example of a hardware configuration when software realizes the functions of the control device 12 according to embodiment 1. When the functions of the control device 12 according to embodiment 1 are realized by software, as shown in Fig. 6, the configuration can include a processor 200 that performs calculations, a memory 202 that stores and reads out programs and threshold data read by the processor 200, an interface 204 that inputs and outputs signals, and a display 206 that displays detection results.
[0029] The processor 200 is an example of a computing means such as an arithmetic unit, a microprocessor, a microcomputer, a CPU (Central Processing Unit), or a DSP (Digital Signal Processor). The memory 202 is an example of a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable ROM), or an EEPROM (Electrically EPROM), a magnetic disk, a flexible disk, an optical disk, a compact disk, a minidisk, or a DVD (Digital Versatile Disc).
[0030] The processor 200 can perform the above-mentioned processing by receiving and sending necessary information via the interface 204, executing a program stored in the memory 202, and referring to the threshold data stored in the memory 202. The calculation results by the processor 200 can be stored in the memory 202. The processing results by the processor 200 can also be displayed on the display 206. Specifically, the display 206 displays the above-mentioned estimated ACC capacity and the determination result by the ACC degradation detection unit 122.
[0031] 7 is a block diagram showing a configuration example in which the functions of the control device 12 according to embodiment 1 are realized by a control circuit. 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, in addition to the ACC capacity estimation unit 121 and the ACC degradation detection unit 122 shown in FIG.
[0032] The ACC capacity estimation unit 121 includes an adder-subtractor 121a, a low-pass filter (LPF) 121b, an effective 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 and the instantaneous value of the three-phase current i Ｌ 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 ease of explanation, the same symbols are used for the digital values below, and the same names are used without distinguishing between analog signals and digital values.
[0034] The outputs of the A / D converters 120a and 120b are input to an adder-subtractor 121a. The output of the A / D converter 120c is input to an ACC estimated capacity calculation unit 121d and a frequency detection unit 120d. The output of the adder-subtractor 121a passes through a low-pass filter 121b and is then input to an effective value calculation unit 121c. The outputs of the effective value calculation unit 121c and the frequency detection unit 120d are input to the ACC estimated capacity calculation unit 121d.
[0035] The process by the adder-subtractor 121a corresponds to the process in step S11 in Fig. 5. The adder-subtractor 121a outputs the capacitor current i ｃ The processing by the effective value calculation unit 121c corresponds to the processing in step S12 in FIG. 5. The three-phase current i ａ The instantaneous value of contains many harmonics due to the switching operation of the three-phase inverter 10. Therefore, before the effective value is calculated by the effective value calculation unit 121c, a process of reducing the harmonics is performed by the low-pass filter 121b.
[0036] The process by the frequency detection unit 120d corresponds to the process at step S13 in Fig. 5. As described above, the three-phase current i ａ The instantaneous value of contains many harmonics, and therefore the three-phase voltage v also contains harmonics. For this reason, it is desirable to perform a filter process to reduce harmonics inside the frequency detection unit 120d.
[0037] The processing by the ACC estimated capacity calculation unit 121d corresponds to the processing of step S14 in FIG. 5 . Furthermore, the processing by the comparator 122a in the ACC degradation detection unit 122 corresponds to the processing of steps S15 to S17 in FIG. 5 . The output of the comparator 122a can be used as a degradation detection signal. Note that, although FIG. 1 illustrates the ACC degradation detection unit 122 configured with a single comparator 122a, this configuration is not limiting. The ACC degradation detection unit 122 may also be configured with multiple comparators. By using multiple comparators and multiple determination thresholds, the degree of degradation of the ACC 22 can be determined in multiple stages. This makes it possible to prompt the user to replace the AC output filter 2 before the AC output filter 2 fails. By installing the vehicle auxiliary power supply device 100 according to the first embodiment in a railway vehicle system, a decrease in the availability of the railway vehicle system can be suppressed.
[0038] As described above, according to the first embodiment, the control device includes a capacitance estimator that estimates the capacitance of each phase of the AC filter capacitor based on information on three-phase voltages, which are voltages at each connection point between the AC filter reactor and the AC filter capacitor, information on a three-phase first current flowing between the three-phase inverter and each connection point, and information on a three-phase second current flowing between each connection point and the load. The information on the three-phase voltages, the three-phase first current, and the three-phase second current is detected by existing sensors. Therefore, there is no need to provide a new sensor. This provides the advantage of being able to measure the capacitance of the AC filter capacitor without increasing the number of components.
[0039] Furthermore, according to the first embodiment, when the output contactor is in a closed state, the capacitance estimator calculates the capacitor currents flowing through the respective phase capacitors constituting the AC filter capacitor based on the three-phase first current and the three-phase second current, and calculates estimated values of capacitance based on the capacitor currents, the three-phase voltage, and the output frequency of the three-phase voltage, thereby achieving the effect of visualizing the deterioration state of the AC filter capacitor.
[0040] In addition, in the first embodiment, 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 estimator. This allows an alarm signal to be output to an operator or manager when degradation of the AC filter capacitor progresses, thereby facilitating maintenance work on the equipment.
[0041] Second Embodiment Fig. 8 is a diagram showing an example of the configuration of a vehicle auxiliary power supply 100A including a power conversion device 1 according to a second embodiment. In Fig. 8, compared to the configuration of the vehicle auxiliary power supply 100 shown in Fig. 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 ACC 24. The ACC 24 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 the neutral point grounded. The other configuration is the same as or equivalent to that of the vehicle auxiliary power supply 100 shown in Fig. 1, and the same or equivalent components are designated by the same reference numerals, and redundant description will be omitted.
[0042] Next, a description will be given of the configuration and operation of the control device 12 according to embodiment 2. 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 the second embodiment calculates the capacitor current i ｃ Calculate the instantaneous value of
[0044] i ｃ = i ａ２ -i Ｌ …(3)
[0045] In the above formula (3), "i ａ２ " is the secondary current flowing through the secondary side of the transformer 9. The secondary current i ａ２ is detected by the current detection unit 15. The current detection unit 15 detects the primary current i ａ１ In this configuration, the secondary current i ａ２ is the primary current i ａ１ can be obtained by converting the detected value of the transformer 9 by the transformation ratio of the transformer 9. Therefore, the three-phase first current in this paper is the primary current i ａ１ and secondary current i ａ２ The current may be any of the following.
[0046] Moreover, the control device 12 according to the second embodiment calculates the ACC estimated capacity using the above equation (3) and the following equation (4).
[0047] ACC estimated capacity = (1 / √3)×i ｃ / (2πfv)...(4)
[0048] As described above, when calculating the estimated ACC capacity, it is necessary to use the phase voltage of the capacitor of each phase and the phase current flowing through the capacitor of each phase. In the circuit configuration of FIG. 8, since the ACC 24 is delta-connected, the capacitor current i ｃ is the line current. In the circuit configuration of FIG. 8, the voltage detection unit 14 detects the line voltage. For this reason, a coefficient of (1 / √3) is added to the above equation (4). The calculation of the above equations (3) and (4) is performed for each of the UVW phases.
[0049] Hereinafter, the process of determining and detecting the deterioration state of the ACC 24 is performed according to the flowchart of Fig. 5. Also, instead of the flowchart of Fig. 5, the process of determining and detecting may be performed by a control circuit of Fig. 7.
[0050] As described above, according to the second embodiment, the control device includes a capacitance estimator that estimates the capacitance of each phase of the AC filter capacitor based on information about three-phase voltages, which are voltages at each connection point between the AC filter reactor and the AC filter capacitor, information about a 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 about a three-phase second current flowing between each connection point and the load. The information about the three-phase voltages, the three-phase first current, and the three-phase second current is detected by existing sensors. Therefore, there is no need to install a new sensor. This provides the advantage of being able to measure the capacitance of the AC filter capacitor without increasing the number of components.
[0051] Furthermore, according to the second embodiment, when the output contactor is in a closed state, the capacitance estimator calculates the capacitor currents flowing through the respective phase capacitors constituting the AC filter capacitor based on the three-phase first current and the three-phase second current, and calculates estimated values of capacitance based on the capacitor currents, the three-phase voltage, and the output frequency of the three-phase voltage, thereby achieving the effect of visualizing the deterioration state of the AC filter capacitor.
[0052] In addition, in the second embodiment, 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 an operator or manager when degradation of the AC filter capacitor progresses, thereby facilitating maintenance work on the equipment.
[0053] Embodiment 3 In the first and second embodiments, the method for calculating the estimated ACC capacity when the output contactor 3 is in the "closed" state has been described. In contrast, in the third embodiment, the method for calculating the estimated ACC capacity when the output contactor 3 is in the "open" state will be described.
[0054] The ACC capacity estimation unit 121 estimates the three-phase current i ａ Based on the instantaneous value of ｃ Calculate the instantaneous value of
[0055] i ｃ = iａ …(5)
[0056] A supplement to the above equation (5) is as follows: Since the output contactor 3 is in the "open" state, no current flows through the load 4. Therefore, the three-phase current i Ｌ also becomes zero, so the above equation (5) holds.
[0057] The subsequent processing is the same as that in the first and second embodiments. Therefore, in the case of the first embodiment, i.e., the configuration in Fig. 1, the estimated ACC capacity is calculated based on the above formula (2). In the case of the second embodiment, i.e., the configuration in Fig. 8, the estimated ACC capacity is calculated based on the above formula (4). Furthermore, the deterioration state of the AC filter capacitor is detected based on the calculated estimated ACC capacity.
[0058] The process according to the third embodiment can be implemented in the vehicle auxiliary power supply device 100, 100A as a test mode or an inspection mode. This configuration makes it possible to continuously monitor the deterioration state of the AC filter capacitor through daily inspections, etc.
[0059] As described above, according to the third embodiment, the control device includes a capacitance estimator that estimates the capacitance of each phase of the AC filter capacitor based on information about three-phase voltages, which are voltages at each connection point between the AC filter reactor and the AC filter capacitor, and information about the three-phase first current flowing between the three-phase inverter and each connection point. The information about the three-phase voltages and the three-phase first current is detected by existing sensors. Therefore, there is no need to provide a new sensor. This provides the advantage of being able to measure the capacitance of the AC filter capacitor without increasing the number of components.
[0060] Furthermore, according to the third embodiment, when the output contactor is in an open state, the capacitance estimator calculates the capacitor currents flowing through the respective phase capacitors constituting the AC filter capacitor based on the three-phase first current, and calculates estimated values of the capacitances based on the capacitor currents, the three-phase voltages, and the output frequency of the three-phase voltages, thereby achieving the effect of visualizing the deterioration state of the AC filter capacitors.
[0061] In addition, in the third embodiment, 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 an operator or manager when the AC filter capacitor deteriorates, thereby facilitating maintenance work on the equipment.
[0062] The method of the third embodiment may be incorporated into a vehicle auxiliary power supply so that it can be implemented in a test mode or an inspection mode. With a vehicle auxiliary power supply configured in this manner, it is possible to obtain the effect of continuously determining the deterioration state of the AC filter capacitor through daily inspections, etc.
[0063] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.
[0064] REFERENCE SIGNS LIST 1 Power conversion device, 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 Vehicle auxiliary power supply device, 120a, 120b, 120c A / D converter, 120d Frequency detection unit, 121 ACC capacity estimation unit, 121a Adder / subtractor, 121b Low-pass filter, 121c Effective value calculation unit, 121d ACC estimated capacity calculation unit, 122 ACC deterioration detection unit, 122a comparator, 200 processor, 202 memory, 204 interface, 206 display.
Claims
1. A power conversion device comprising: a three-phase inverter that converts input power into three-phase AC power and supplies the converted three-phase AC power to a load via an AC output filter that has an AC filter reactor and an AC filter capacitor; and a control device that controls the operation of the three-phase inverter, wherein the control device comprises a capacitance estimation unit that estimates the capacitance of each phase of the AC filter capacitor based on information on three-phase voltages that are voltages at each connection point between the AC filter reactor and the AC filter capacitor, and information on a three-phase first current that flows between the three-phase inverter and each of the connection points.
2. The power conversion device according to claim 1, wherein an output contactor is provided between the three-phase inverter and the load, and the capacitance estimation unit calculates the estimated value of the capacitance based on the three-phase first current, the three-phase voltage, and the output frequency of the three-phase voltage when the output contactor is in an open state.
3. The power conversion device according to claim 1 or 2, characterized in that the control device is provided with a deterioration detection unit that detects the deterioration state of the AC filter capacitor based on the estimated value of the capacitance estimated by the capacitance estimation unit.
4. The power conversion device according to claim 1, wherein an output contactor is provided between the three-phase inverter and the load, and information on a three-phase second current flowing between each of the connection points and the load is input to the capacity estimation unit, and the capacity estimation unit calculates, when the output contactor is closed, a capacitor current flowing in each of the capacitors of each phase that constitute the AC filter capacitor based on the three-phase first current and the three-phase second current, and calculates an estimated value of the capacitance based on the capacitor current, the three-phase voltage, and an output frequency of the three-phase voltage.
5. The power conversion device according to claim 4, characterized in that the control device is provided with a deterioration detection unit that detects the deterioration state of the AC filter capacitor based on the estimated value of the capacitance estimated by the capacitance estimation unit.
6. An auxiliary power supply device for a vehicle comprising: the power conversion device according to any one of claims 1 to 3; the AC output filter; a voltage detector for detecting the three-phase voltage; and a first current detector for detecting the three-phase first current, the auxiliary power supply device being mounted on a railway vehicle and using DC power or AC power supplied from an overhead line to supply the three-phase AC power to an auxiliary load, which is the load other than the main motor.
7. An auxiliary power supply device for a vehicle comprising: the power conversion device according to claim 4 or 5; the AC output filter; a voltage detector for detecting the three-phase voltage; a first current detector for detecting the three-phase first current; and a second current detector for detecting the three-phase second current, the auxiliary power supply device being mounted on a railway vehicle and using DC power or AC power supplied from an overhead line to supply the three-phase AC power to an auxiliary load, which is the load other than the main motor.
8. The vehicle auxiliary power supply device according to claim 6 or 7, characterized in that the AC filter reactors are connected to the output terminals of the three-phase inverter, and the AC filter capacitors are wired in a Y configuration at the load side ends of the AC filter reactors.
9. The vehicle auxiliary power supply device according to claim 7 or 8, characterized in that it comprises a transformer having a primary winding and a secondary winding, the primary winding being connected to each output terminal of the three-phase inverter, and the AC filter capacitors are delta-connected and connected to each output terminal of the secondary winding of the transformer.