Power conversion device for railway vehicle

Abstract

In this power conversion device for a railway vehicle, a converter control unit (242) provided in a control device (240) comprises: a relative voltage calculation unit (501) that calculates a relative voltage, which is a reference for current control of a converter (210), on the basis of a detected overhead line voltage value; and a voltage phase estimation unit (502) that estimates, on the basis of the relative voltage, the phase of the AC voltage applied to the auxiliary power supply device (107) during the non-power-supply period. The relative voltage calculation unit (501) includes: a phase difference estimation unit (810) that estimates a phase difference between a first phase and a second phase, the first phase being a phase of a first voltage when the overhead line voltage detected by the ACPT (102) is set to the first voltage after the end of the non-power-supply period, and the second phase being a phase of a second voltage when the overhead line voltage is set to the second voltage after the end of the non-power-supply period; the second phase is the phase of a second AC voltage estimated by a voltage phase estimation unit (502) on the basis of the overhead line voltage detected by the ACPT (102) before the start of the non-power supply period; and a switching unit (820) that switches a symbol of a frequency correction amount for correcting the frequency of the second voltage on the basis of an estimated phase difference, which is an estimated value of the phase difference.

Description

Technical Field

[0001] The present disclosure relates to a power conversion device for a railway vehicle that receives alternating current supplied from an overhead line and travels thereby. Background Art

[0002] In an alternating current electrified railway line, the feeding section, which is the range powered by one substation, is limited, and the voltage phases of the alternating current from each substation are different. Therefore, in a railway line, an area where power supply is not possible is provided at the boundary of the feeding section. This area is called a "dead zone". Thus, when a railway vehicle that receives alternating current supplied from an overhead line and travels passes through the dead zone, the power supply from the overhead line is interrupted. On the other hand, at this time, the regenerative power from the propulsion motor for driving the railway vehicle is supplied to auxiliary equipment mounted on the railway vehicle, so that power supply to the auxiliary equipment can be continued as in normal travel. This operation is called "pump-back". In addition, auxiliary equipment is the name for equipment other than the propulsion motor among the equipment mounted on a rail vehicle to supply power. Power is supplied to the auxiliary equipment by a power conversion device called an auxiliary power supply device.

[0003] After passing through the dead zone, if power supply is restored from the overhead line, the circuit breaker of the power receiving section is turned on, and the power supply is switched to the normal overhead line power supply. Here, when the overhead line is an alternating current overhead line, when switching to the overhead line power supply, in order to prevent an excessive current from flowing, it is necessary to turn on the circuit breaker with the voltage phases matched between the voltage applied to the main transformer before switching and the overhead line voltage applied after switching. In particular, in the case of a circuit configuration in which the auxiliary power supply device is connected to the tertiary winding of the main transformer, phase matching is performed while continuing to apply an alternating voltage to the main transformer.

[0004] Against the above technical background, Patent Document 1 below discloses a technique in which the overhead line voltage phase, which is the phase of the overhead line voltage, is directly obtained, and the converter voltage phase is made to catch up with the overhead line voltage phase by increasing the frequency, thereby performing phase synchronization between the converter voltage and the overhead line voltage. Prior Art Documents Patent Documents

[0005] Patent Document 1: Japanese Patent No. 6510060 Gazette Summary of the Invention Technical Problem to be Solved by the Invention

[0006] However, the above-mentioned Patent Document 1 does not describe a specific method for directly obtaining the voltage phase of the overhead line. In addition, as described in Patent Document 1, the method for directly calculating the voltage phase of the overhead line has the following problems: when the frequency of the overhead line voltage deviates from the rated value, it is difficult to perform phase detection, and the time for phase synchronization for matching the converter voltage phase with the overhead line voltage phase becomes longer.

[0007] The present disclosure has been made in view of the above circumstances, and an object thereof is to obtain a power conversion device for a railway vehicle that can suppress an increase in the time required for phase synchronization even when the frequency of the overhead line voltage deviates from the rated value. Technical means for solving technical problems

[0008] To solve the above problems and achieve the above object, the power conversion device for a railway vehicle according to the present disclosure is mounted on a railway vehicle including a main transformer, a switch, and a voltage detector. The primary winding of the main transformer is connected to the overhead line via a power receiving unit, the switch electrically disconnects or connects the main transformer and the overhead line, and the voltage detector is provided between the overhead line and the switch to detect the overhead line voltage applied from the overhead line. The power conversion device for a railway vehicle includes a first power conversion device, a second power conversion device, and a control device. The first power conversion device is connected to the secondary winding of the main transformer, has a converter that converts the AC voltage applied through the main transformer into a DC voltage, and is connected to a propulsion motor for driving the railway vehicle. The second power conversion device is connected to the tertiary winding of the main transformer and supplies power to auxiliary equipment mounted on the railway vehicle. The control device controls the operations of the switch, the first power conversion device, and the second power conversion device. The control device includes a converter control unit that controls the converter during a non-power supply period when power is not supplied from the overhead line, and performs control to supply the regenerative power generated by the propulsion motor to the second power conversion device via the main transformer. The converter control unit includes a reference voltage calculation unit and a voltage phase estimation unit. The reference voltage calculation unit calculates a reference voltage that serves as a reference for current control of the converter based on the detected value of the overhead line voltage. The voltage phase estimation unit estimates the phase of the AC voltage applied to the second power conversion device during the non-power supply period based on the reference voltage. The reference voltage calculation unit includes a phase difference estimation unit and a switching unit. The phase difference estimation unit estimates the phase difference between a first phase that is the phase of a first voltage and a second phase that is the phase of a second voltage. The first voltage is the overhead line voltage detected by the voltage detector after the end of the non-power supply period. The second voltage is the AC voltage estimated by the voltage phase estimation unit based on the overhead line voltage detected by the voltage detector before the start of the non-power supply period. The switching unit switches the sign of the frequency correction amount for correcting the frequency of the second voltage based on the estimated phase difference that is the estimated value of the phase difference. Advantages of the invention

[0009] According to the power conversion device for railway vehicles involved in the present disclosure, even if the overhead line voltage frequency deviates from the rated value, an increase in the time required for phase synchronization can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 FIG. is a diagram showing a structural example of an electrical system of a railway vehicle system including a power conversion device for railway vehicles according to an embodiment. Figure 2 FIG. shows Figure 1 a structural example of the main conversion device shown. Figure 3 FIG. is a diagram for explaining the energy flow during normal operation in the power conversion device for railway vehicles according to the embodiment. Figure 4 FIG. is a diagram for explaining the energy flow during a power-off period in the power conversion device for railway vehicles according to the embodiment. Figure 5 A timing chart for explaining the operation during pump-back in the embodiment. Figure 6 FIG. is a block diagram showing a structural example of a converter control unit according to the embodiment. Figure 7 FIG. is a diagram for explaining a conventional method using a PLL. Figure 8 FIG. is a block diagram showing a structural example of a relative voltage calculation unit according to the embodiment. Figure 9 FIG. is a diagram for explaining the effect of shortening the time required for phase synchronization when using the relative voltage calculation unit according to the embodiment. Figure 10 FIG. is a diagram showing the voltage waveform and current waveform of the main part in a comparative example when the actual voltage phase difference is 180 [°]. Figure 11 FIG. is a diagram showing the PLL operation waveform in a comparative example when the actual voltage phase difference is 180 [°]. Figure 12 FIG. is a diagram showing the voltage waveform and current waveform of the main part in the present method when the actual voltage phase difference is 180 [°]. Figure 13 FIG. is a diagram showing the PLL operation waveform in the present method when the actual voltage phase difference is 180 [°]. Figure 14 FIG. is a diagram showing the voltage waveform and current waveform of the main part in the present method when the actual voltage phase difference is 150 [°]. Figure 15 FIG. is a diagram showing the PLL operation waveform in the present method when the actual voltage phase difference is 150 [°]. Figure 16 It is a block diagram showing an example of the hardware structure that implements the functions of the converter control unit in the embodiment. Figure 17 It is a block diagram showing another example of the hardware structure that implements the functions of the converter control unit in the embodiment. Detailed Embodiment

[0011] Hereinafter, the power conversion device for railway vehicles according to the embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, hereinafter, it will be simply referred to as "connection" without distinguishing between physical connection and electrical connection. That is, the term "connection" includes both cases where components are directly connected to each other and cases where components are indirectly connected through another component.

[0012] Embodiment. Figure 1 It is a diagram showing an example of the structure of the electrical system of a railway vehicle system including the power conversion device for railway vehicles according to the embodiment. The railway vehicle system according to the embodiment is configured to include a power receiving unit 101, an ACPT (Alternating Current Potential Transformer) 102 as a voltage detector, a switch 103, a main transformer 104, a main conversion device 105, a propulsion motor 106, and an auxiliary power supply device 107. In addition, although Figure 1 the main conversion device 105 has four units and the propulsion motor 106 has four units, this is only an example, and the number of units can be different. In addition, Figure 1 one propulsion motor 106 is connected to one main conversion device 105, but it can also be a structure in which multiple propulsion motors 106 are connected to one main conversion device 105. In addition, Figure 1 one auxiliary power supply device 107 is connected to the main transformer 104, but it can also be a structure in which multiple auxiliary power supply devices 107 are connected to the main transformer 104. In addition, in Figure 1 the main conversion device 105 and the auxiliary power supply device 107 constitute the power conversion device for railway vehicles according to the embodiment.

[0013] The power receiving unit 101 is a device for a railway vehicle to receive alternating current from the overhead line 100. Examples of the power receiving unit 101 are a pantograph, a collector shoe, etc. It is assumed that the pantograph installed on the upper part of the railway vehicle supplies power to the railway vehicle, but it can also be a third rail provided beside the track.

[0014] The switch 103 is a device for electrically disconnecting and closing the main transformer 104 and the overhead line 100. An example of the switch 103 is a circuit breaker, and a vacuum circuit breaker (VCB) is usually used for railway vehicles. In addition, as long as it can electrically open and close, that is, disconnect and connect, between the main transformer 104 and the overhead line 100, it may not be a circuit breaker.

[0015] ACPT102 is a device for measuring the received voltage of the power receiving unit 101. ACPT102 is provided between the overhead line 100 and the switch 103 and detects the overhead line voltage applied from the overhead line 100.

[0016] The main transformer 104 includes a primary winding 141, a secondary winding 142, and a tertiary winding 143. The primary winding 141 is connected to the overhead line 100 via the power receiving unit 101 and the switch 103. In addition, the secondary winding 142 is connected to the main conversion device 105, and the tertiary winding 143 is connected to the auxiliary power supply device 107. The overhead line voltage is applied to the primary winding 141, and voltages determined by the turns ratio with the primary winding 141 are generated on the secondary winding 142 and the tertiary winding 143. The secondary winding 142 corresponding to the number of main conversion devices 105 is provided, and the tertiary winding 143 corresponding to the number of auxiliary power supply devices 107 is provided. Basically, each winding is connected to each device one-to-one, but it may also be a structure in which one winding is connected to multiple devices via a reactor. In addition, the voltage applied to the primary winding 141 is a reference voltage that is the reference for current control of the converter 210. In this article, this reference voltage is referred to as the "relative voltage". In addition, in this article, this relative voltage is obtained by calculation.

[0017] The main conversion device 105 includes a converter 210 and an inverter 230. The converter 210 is connected to the secondary winding 142 of the main transformer 104 and converts the AC voltage applied via the main transformer 104 into a DC voltage. The inverter 230 is connected to the propulsion motor 106, converts the DC voltage applied from the converter 210 into a drive voltage for the propulsion motor 106, and applies this drive voltage to the propulsion motor 106. In addition, in this article, the main conversion device 105 is sometimes referred to as the "first power conversion device".

[0018] The propulsion motor 106 is a motor for driving a railway vehicle. The railway vehicle obtains driving force by the rotation of the propulsion motor 106 and travels. In addition, the railway vehicle accelerates or decelerates by the torque generated by the propulsion motor 106.

[0019] The auxiliary power supply device 107 is connected to the tertiary winding 143 of the main transformer 104 and supplies power to the above-mentioned auxiliary devices. Examples of the auxiliary devices include in-vehicle lighting devices, door switch devices, air conditioning devices, safety devices, compressors, batteries, control power supplies, etc. In addition, in this text, the auxiliary power supply device 107 is sometimes referred to as the "second power conversion device".

[0020] Figure 2 is a diagram showing Figure 1 a structural example of the main conversion device 105 shown. The main conversion device 105 includes a converter 210, a smoothing capacitor 220, an inverter 230, and a control device 240. In addition, the control device 240 includes a converter control section 242 and an inverter control section 244.

[0021] The converter 210 includes a primary side terminal 211 and a secondary side terminal 212. The converter 210 can convert a single-phase AC voltage applied to the primary side terminal 211 and a DC voltage applied to the secondary side terminal 212 into each other. This operation is controlled by the converter control section 242. The converter 210 controls the power transmitted to the inverter 230 side by adjusting the voltage of the primary side terminal 211. In addition, a current sensor 213 is disposed on one of the primary side terminals 211. The current sensor 213 detects the current flowing into the primary side of the converter 210. In addition, Figure 2 a three-level converter having 3 secondary side terminals 212 and capable of outputting 3 kinds of potentials to the secondary side is exemplified, but it is not limited to this example. The number of secondary side terminals 212 can be 2, or can be 4 or more. A structure in which the number of secondary side terminals 212 is 2 is called a two-level converter.

[0022] The converter 230 includes a primary side terminal 231 and a secondary side terminal 232. The converter 230 can convert a DC voltage applied to the primary side terminal 231 and an AC voltage applied to the secondary side terminal 232 into each other. This operation is controlled by the inverter control section 244. The inverter 230 controls the output torque of the propulsion motor 106 by adjusting the voltage of the secondary side terminal 232. When the propulsion motor 106 is a three-phase AC motor, the voltage output to the secondary side terminal 232 is a three-phase AC voltage. In addition, Figure 2 a two-level converter having 2 primary side terminals 231 and capable of outputting 2 kinds of potentials to the primary side is exemplified, but it is not limited to this example. The number of primary side terminals 231 can be three or more. A structure in which the number of primary side terminals 231 is 3 is called a three-level converter.

[0023] The smoothing capacitor 220 is connected between the secondary side terminal 212 of the converter 210 and the primary side terminal 231 of the inverter 230, and has a function of suppressing fluctuations in the DC voltage. When both the converter 210 and the inverter 230 have a two-level structure, the smoothing capacitor 220 can have a structure with only one capacitor. In addition, the voltage sensor 221 is arranged in parallel with the smoothing capacitor 220. The voltage sensor 221 detects the voltage across the smoothing capacitor 220, that is, the capacitor voltage.

[0024] Figure 3 It is a diagram for explaining the energy flow during normal operation in the power conversion device for railway vehicles according to the embodiment. In addition, Figure 4 It is a diagram for explaining the energy flow during the non-power supply period in the power conversion device for railway vehicles according to the embodiment. In addition, the normal operation refers to the state where the power from the overhead line 100 is normally applied to the main transformer 104. In addition, the non-power supply period is a concept that includes not only the period when the railway vehicle actually passes through the dead zone, but also the periods before and after during which the switch is in the off state. That is, the non-power supply period refers to the period during which the main transformer 104 and the overhead line 100 are electrically disconnected and no power is supplied from the overhead line 100 to the main transformer 104.

[0025] During normal operation, the power required to drive the railway vehicle is supplied to the main conversion device 105 and the auxiliary power supply device 107 via the power receiving unit 101, the switch 103, and the main transformer 104. The main conversion device 105 converts the supplied power into driving power for the propulsion motor 106 and drives the propulsion motor 106. The auxiliary power supply device 107 converts the supplied power into driving power for the auxiliary equipment and operates the auxiliary equipment.

[0026] During the non-power supply period, power cannot be supplied from the overhead line 100. Therefore, the converter control unit 242 provided in the control device 240 regenerates the kinetic energy of the propulsion motor 106 and performs a pump-back operation to supply the regenerated power at this time to the auxiliary power supply device 107 via the main conversion device 105 and the main transformer 104. In the following description, when there is a description of the main conversion device 105, it refers to the main conversion device 105 that performs the pump-back operation. In addition, each main transformer 104 has one main conversion device 105 for performing the pump-back operation. By performing the pump-back operation with one main conversion device 105, it is possible to prevent the regenerated power supplied to the main transformer 104 from becoming unstable. The one main conversion device 105 for performing the pump-back operation can be determined in advance, or can be specified by the train information management device that manages the train information. The non-power supply period accompanied by passing through the dead zone is short, and the amount of power consumed by the auxiliary power supply device 107 during this period is sufficiently small compared to the kinetic energy of the propulsion motor 106 and the railway vehicle. Therefore, even if only one main conversion device 105 performs the pump-back operation, it is possible to avoid a state where the train decelerates rapidly.

[0027] Figure 5 A timing chart for explaining the operation during pump-back in the embodiment. Figure 5 The horizontal axis in [ ] represents time. In addition, in the Figure 5 vertical axis direction, the detection waveform of ACPT102, the dead zone passage pre-warning signal, the torque mode, the status signal of pump-back, the status signal of switch 103, and the voltage waveform for converter control are shown in sequence from the upper side.

[0028] Before the railway vehicle passes through the dead zone, the dead zone passage pre-warning signal is output. Specifically, in the Figure 5 example, the dead zone passage pre-warning signal is output at time t1, and the output of the dead zone passage pre-warning signal is cancelled at time t10. Regeneration starts at time t2, and pump-back starts at time t3. The switch 103 is turned off at time t4, and the off state continues until time t11. The period from time t5 to time t6 is the actual period of passing through the dead zone. During the period from time t7 to time t8, control is performed to match the output voltage waveform of the converter 210 with the detection waveform of ACPT102. Pump-back ends at time t9, and the operation transfers from regeneration to power operation at time t12.

[0029] Next, the operations of the main transformer 104 and the main conversion device 105 will be described with reference to the Figure 5 timing chart. First, when there is power supply from the overhead line 100, the converter 210 operates to keep the capacitor voltage constant. The main transformer 104 outputs a single-phase AC voltage to the primary side terminal 211 of the converter 210 so that the converter 210 can receive the required power. The converter 210 outputs a DC voltage to the secondary side terminal 212 so that the smoothing capacitor 220 can follow the voltage according to the command value. On the other hand, the inverter 230 outputs a voltage to the secondary side terminal 232 so that the propulsion motor 106 can output torque according to the command value.

[0030] When the dead zone passage pre-warning signal is output and received at time t1, the inverter 230 limits the power operation torque and then stops supplying current to the propulsion motor 106. As a result, the propulsion motor 106 rotates by inertia, and the railway vehicle is in the coasting state. When switching to the pump-back operation at time t3, the inverter 230 operates so that the power required to maintain the capacitor voltage is regenerated from the propulsion motor 106. After starting the pump-back, when the regenerative power from the main conversion device 105 is substantially the same as the power consumption of the auxiliary equipment connected to the auxiliary power supply device 107, the current flowing through the switch 103 approaches zero. Thus, the switch 103 can be turned off at time t4.

[0031] During the period from the actual time t5 when passing through the dead zone to time t6, the overhead line voltage cannot be measured. Therefore, at time t4 when the state signal of the switch 103 changes to off, that is, at time t4 before time t5, the control is switched to not refer to the overhead line voltage. Specifically, the converter 210 outputs a voltage with a constant amplitude and frequency to the primary side terminal 211 without referring to the overhead line voltage. Here, the power converted by the converter 210 depends on the load of the auxiliary power supply device 107, so the capacitor voltage cannot be controlled. Therefore, the capacitor voltage control at this time is the responsibility of the inverter control unit 244. The inverter control unit 244 controls the inverter 230 so that the torque command for the propulsion motor 106 becomes the amount of regenerative torque required to obtain the power necessary to maintain the capacitor voltage. The control without referring to the overhead line voltage continues until time t7 after passing through the dead zone.

[0032] After time t6 at the time point when the railway vehicle passes through the dead zone, the ACPT 102 resumes measuring the overhead line voltage. However, since the phases of the overhead line voltage and the voltage generated by the converter 210 are different, if the switch 103 is closed at this time point, an excessive inrush current may flow through the main transformer 104. To prevent this excessive current, the converter 210 performs control to gradually match the generated voltage with the detection waveform of the ACPT 102. Specifically, while continuing to supply power to the auxiliary power supply device 107, the converter 210 performs control to gradually change the frequency of the generated voltage so that the phase of the generated voltage is synchronized with the phase of the overhead line voltage. Figure 5 An example is shown where the phase of the generated voltage is synchronized with the phase of the overhead line voltage at time t8, the pump-back ends at a subsequent time t9, and the switch 103 is closed at a subsequent time t11. After time t11, the power supply from the overhead line 100 resumes, the converter 210 returns to DC voltage control, and the inverter 230 returns to motor torque control.

[0033] In this article, after the end of the non-power supply period, the overhead line voltage detected by the ACPT 102 is sometimes referred to as the "first voltage", and the phase of the first voltage is sometimes referred to as the "first phase". In addition, in this article, the AC voltage generated by the converter control unit 242 during the non-power supply period based on the overhead line voltage detected by the ACPT 102 before the start of the non-power supply period is sometimes referred to as the "second voltage", and the phase of the second voltage is sometimes referred to as the "second phase".

[0034] Figure 6 It is a block diagram showing a structural example of the converter control unit 242 according to the embodiment. As Figure 6As shown, the converter control unit 242 in the embodiment includes a relative voltage calculation unit 501, a voltage phase estimation unit 502, a current control unit 503, a voltage command calculation unit 504, and a converter drive signal generation unit 505.

[0035] The relative voltage calculation unit 501 calculates a relative voltage command value V * , 2 , * , * , 2 , 2 , S as the command value of the relative voltage V 2 . When the switch 103 is closed, the voltage value is V 2 * = V 1 = V 2 * , and when the switch 103 is open, the voltage value is substantially different.

[0036] The voltage phase estimation unit 502 estimates an estimated voltage phase θ 2 * as the estimated value of the voltage phase of the overhead line voltage V 1 . The relative voltage command value V S is a single-phase sine wave. The voltage phase estimation unit 502 calculates the estimated voltage phase θ 2 * based on V 1 = V 2 * , that is, the relative voltage command value V 2 * in normal times. Specifically, the voltage phase estimation unit 502 regards the relative voltage command value V S as a sine wave, detects the timing when the instantaneous voltage of the relative voltage command value V 2 * changes from negative to positive, and performs an operation of setting this timing as 0° of the phase. Therefore, it is required that the relative voltage command value V 2 * is a sine wave with small ripple.

[0037]

[0038] In normal times, the current control unit 503 performs output voltage correction to make the capacitor voltage V dc follow the capacitor voltage command value V dc * as its command value. During the pump-back process, it performs output voltage correction to make the relative voltage V 2 follow the relative voltage command value V 2 * . Specifically, the current control unit 503 is based on the assumed load power P m in the inverter 230 and the capacitor voltage V detected by the voltage sensor 221 in normal timesdc The detected value is used in an operation to make the capacitor voltage V dc follow the capacitor voltage command value V dc * The required current amplitude. Then, the current control unit 503 calculates the voltage drop V in the main transformer 104 based on the calculated current amplitude and the estimated voltage phase θ output from the voltage phase estimation unit 502 S On the other hand, during the pump-back process, the current sensor 213 detects the current I flowing into the primary side of the converter 210 tr , and the current control unit 503 calculates the voltage drop V in the main transformer 104 based on the detected value of the current I S S tr . tr .

[0038] The voltage command calculation unit 504 calculates the primary side voltage command V based on the relative voltage command value V 2 * and the voltage drop V in the main transformer 104 tr . Specifically, the voltage command calculation unit 504 calculates the voltage command V by subtracting the voltage drop V ac * from the relative voltage command value V 2 * . tr to calculate the voltage command V ac * .

[0039] The converter drive signal generation unit 505 generates a switching command S based on the voltage command V ac * , the estimated voltage phase θ S and the detected value of the capacitor voltage V dc , and outputs the generated switching command S c to the converter 210. Although not shown in the figure, the converter 210 includes a plurality of switched elements connected in a bridge. The switching command S c is an instruction for turning on or off each of the plurality of switched elements at a desired timing. The switching command S c can be generated by using, for example, the PWM method, which is a well-known control method. According to the switching command S c , a voltage corresponding to the voltage command V c ac * is output to the primary side terminal 211 of the converter 210.

[0040] Next, the problems of the existing method will be described. As described above, the relative voltage calculation unit 501 calculates the relative voltage V as 1 based on the overhead line voltage V obtained from the ACPT 102 2The relative voltage command value V of the command value 2 * . A PLL (Phase Locked Loop) is usually used for the relative voltage command value V 2 * . The PLL, also known as a phase-locked loop, is a method of calculating a desired phase through feedback control that makes the phase difference between the phase of an input signal and the phase of an output signal consistent. In the power conversion device for railway vehicles of the present disclosure, the use of the PLL is the same, but the existing method has the following problems. Figure 7 is a diagram for explaining an existing method using a PLL.

[0041] In Figure 7 , the sine wave represented by the solid line is a curve for phase estimation. The horizontal axis represents the actual voltage phase difference θ 1 -θ 2 , and the vertical axis represents the estimated phase difference Δθ in the existing method. The dashed line is a straight line representing the relationship where the estimated phase difference Δθ is consistent with the actual voltage phase difference θ 1 -θ 2 . In the control of phase estimation, the difference between the actual and the dashed line is represented as an error component of the estimated phase difference Δθ. Here, in the existing method, when the value of the actual voltage phase difference θ 1 -θ 2 is small, (θ 1 -θ 2 )≈sin(θ 1 -θ 2 ) is used, and the value of sin(θ 1 -θ 2 ) is used for the calculation of the estimated phase difference Δθ. However, as Figure 7 shows, when the absolute value of the actual voltage phase difference θ 1 -θ 2 exceeds 30 [°], the difference between θ 1 -θ 2 and sin(θ 1 -θ 2 ) increases, and when the absolute value of the actual voltage phase difference θ 1 -θ 2 further exceeds 90 [°], this difference increases sharply. Therefore, there is a problem that when the value of the actual voltage phase difference θ 1 -θ 2 is large, the estimated phase difference Δθ is estimated to be less than the actual value, and phase synchronization takes time. In addition, especially when the absolute value of the actual voltage phase difference θ 1 -θ 2 is 180 [°], sin(θ 1 -θ2 ) = 0, there is a fatal problem that the PLL cannot function fully and cannot correct the voltage phase.

[0042] Next, a control method that can solve the above problems will be described. Figure 8 is a block diagram showing a structural example of the relative voltage calculation unit 501 according to the embodiment. As Figure 8 shown, the relative voltage calculation unit 501 according to the embodiment is configured to include gain application units 601, 605, a cosine calculation unit 602, multiplication units 603, 610, 801, 804, low-pass filters (LPFs) 604, 802, switches 606, 611, 805, an addition unit 607, an integration unit 608, a sine calculation unit 609, a band-pass filter (BPF) 612, and a sign determination unit 803. In addition, in Figure 8 , the cosine calculation unit 602, the multiplication unit 603, and the LPF 604 constitute a phase difference estimation unit 810, and the multiplication units 801, 804, the LPF 802, the sign determination unit 803, and the switch 805 constitute a switching unit 820.

[0043] Next, the operation of the Figure 8 shown relative voltage calculation unit 501 will be described. First, the gain application unit 601 applies a gain N to the overhead line voltage V obtained from the ACPT 102. 1 As a result, the voltage value of the voltage V output from the gain application unit 601 b is converted to a voltage equivalent to that of the secondary winding 142 of the main transformer 104. In addition, the gain N is a value obtained by dividing the number of turns of the primary winding 141 of the main transformer 104 by the number of turns of the secondary winding 142.

[0044] Next, the cosine calculation unit 602 calculates a cosine value cosθ using the current voltage phase θ generated inside the relative voltage calculation unit 501. This process is equivalent to advancing the voltage waveform by 90° and generating a voltage waveform with a peak value of ±1. Here, when using the angular frequency ω 0 and the phase θ at time 0 [s] 2 , the current voltage phase θ is represented by the following equation (1). In addition, it is assumed that the voltage V output from the gain application unit 601 b uses the frequency ω 0 and the phase θ at time 0 [s] 1 is represented by the following equation (2).

[0045] [Mathematical formula 1] θ [rad] = ω 0 t + θ 2 …(1) [Mathematical Formula 2]

[0046] In the above formula (2), V S * is the rated voltage amplitude which is the rated value of the overhead line voltage V 1 . The multiplication unit 603 multiplies the output of the gain imparting unit 601 by the output of the cosine operation unit 602, and the multiplication result is represented by the following formula (3).

[0047] [Mathematical Formula 3]

[0048] The right side of the above formula (3) is the sum of the voltage component that changes with time and the voltage component that pulsates at twice the angular frequency of the voltage. Therefore, in order to retain only the former component and remove the latter component, the LPF 604 is provided. For example, the transfer function of the LPF 604 is set to the following formula (4). If the LPF 604 set in this way is used, the component with an angular frequency of 2ω 0 can be sufficiently removed.

[0049] [Mathematical Formula 4]

[0050] The output of V S * {sin(θ 1 -θ 2 )} / 2 is obtained from the LPF 604. As described above, in the case of the existing method, assuming that the difference between θ 1 and θ 2 is small enough, the output of the LPF 604 is regarded as being substantially equal to "V S * (θ 1 -θ 2 ) / 2" for processing.

[0051] The gain imparting unit 605 applies the gain K PLL to the output of the LPF 604. Through this process, the output of the gain imparting unit 605 is converted into the frequency correction amount Δω. The frequency correction amount Δω is input to the switch 606 via the switch 805. The operation of the switch 805 will be described later.

[0052] Here, the operation using the frequency correction amount Δω will be described. When the frequency correction amount Δω is used, the frequency of the voltage V b can be increased or decreased. For example, when the voltage phase of the overhead line voltage V 1 is ahead of the estimated voltage phase θ 1 which is the estimated value of the voltage phase of the overhead line voltage V SWhen, by increasing the voltage V b frequency, the voltage phase θ is estimated S to perform an operation to catch up with the voltage phase of the overhead line voltage V 1 On the contrary, when the voltage phase of the overhead line voltage V 1 lags behind the estimated voltage phase θ S When, by decreasing the voltage V b frequency, the voltage phase θ is estimated S to perform an operation to be caught up with by the voltage phase of the overhead line voltage V 1 .

[0053] The switch 606 is fixed to be turned on during normal operation, turned off during pump-back, and restored to turn on when power supply to the overhead line is restarted after passing through the dead zone. Therefore, during normal operation, the switch 606 is input with the frequency correction amount Δω, and during pump-back, it is input with 0. Thus, in the control system, when the switch 606 is turned on, the PLL operates, and when the switch 606 is turned off, the PLL does not operate, and a voltage with a fixed frequency is output to the primary side terminal 211.

[0054] In the adder 607, the frequency correction amount Δω or 0 is added to the rated angular frequency ω 0 obtained by multiplying the rated frequency of the overhead line 100 by 2π, and the result is input to the subsequent integrator 608. That is, the adder 607 converts the output of the switch 606 into the frequency of the voltage to be output to the primary side terminal 211 of the converter 210. Usually, 16.7, 25, 50, 60 [Hz], etc. are used as the rated frequency of the AC overhead line for AC electrification.

[0055] The integrator 608 integrates the output of the adder 607 and outputs the integration value as the above-mentioned voltage phase θ to the cosine operation unit 602 and the sine operation unit 609. Here, during normal operation, the switch 606 is controlled to be turned on, so the overhead line voltage phase is stored in the integrator 608. In addition, during the power-off period, based on the overhead line voltage phase stored in the integrator 608, the phase changes at the rated angular frequency, and after passing through the dead zone, the processing of the PLL becomes effective again to make the phase perform an operation to approach the overhead line voltage phase.

[0056] The sine operation unit 609 calculates the sine value sinθ using the voltage phase θ. The multiplier 610 multiplies the rated voltage amplitude V 1 which is the rated value of the overhead line voltage V S * by the output of the sine operation unit 609, and sets the multiplication result as the PLL voltage V 2p .

[0057] The switch 611 is normally fixed in the off state, is turned on during the power-off period, and returns to the off state after passing through the dead zone. Here, since the switch 103 is closed normally, the voltage V output from the gain imparting unit 601 is used as a signal that serves as the basis for the relative voltage command value V b On the other hand, during the power-off period, the PLL voltage V output from the multiplication unit 610 is used as a signal that serves as the basis for the relative voltage command value V 2 * Finally, the output of the switch 611 is input to the BPF 612, the fundamental wave component is extracted by the BPF 612, and is output as the relative voltage command value V 2p Since harmonics caused by the operation of the converter 210 are superimposed on the overhead line voltage V 2 * Therefore, settings are made to remove the superimposed harmonic components.

[0058] In addition, the timing for changing the switch 611 from on to off is after the timing when the phase of the relative voltage command value V 2 * coincides with the phase of the overhead line voltage V 1 and is after the switch 103 is turned on. In addition, even if the switch 611 is turned off after the switch 103 is turned on, since the phase of the relative voltage command value V

[0059] coincides with the phase of the overhead line voltage V 2 * the relative voltage command value V 1 does not change significantly before and after the switch 611 is switched. 2 * Here, a method for determining the completion of phase synchronization is also described. Since through the processing of the BPF 612, the relative voltage command value V 1 becomes a sine wave having only a fundamental wave component with almost no distortion, the sign is switched every half cycle of the fundamental wave. Monitor the overhead line voltage V 2 * at the moment of this sign change. If the instantaneous voltage is below a specified value, it is determined that the phase synchronization is completed. Instead of this method, if the difference between the slope of the overhead line voltage V

[0060] at the moment of sign change and the slope of the relative voltage command value V 2 * is below a specified value, it can be determined that the phase synchronization is completed. In addition, the specified value for determination can be determined based on the allowable inrush current in the main transformer 104. 1 at the moment of this sign change. If the instantaneous voltage is below a specified value, it is determined that the phase synchronization is completed. Instead of this method, if the difference between the slope of the overhead line voltage V 1 at the moment of sign change and the slope of the relative voltage command value V 2 * is below a specified value, it can be determined that the phase synchronization is completed. In addition, the specified value for determination can be determined based on the allowable inrush current in the main transformer 104.

[0061] The operation of the above-mentioned switching unit 820 that has not been described in the relative voltage operation unit 501 will be described. First, in the multiplication unit 801, the output of the gain assignment unit 601 is multiplied by the output of the cosine operation unit 609, and the multiplication result is represented by the following equation (5).

[0062] [Equation 5]

[0063] The right side of the above equation (5) is the difference between the voltage component that changes with time and the voltage component that pulsates at twice the angular frequency of the voltage. The former component is retained only by the LPF 802, and the latter component is removed. Similar to the LPF 604, as long as the LPF 802 can sufficiently remove the component with an angular frequency of 2ω 0 it is sufficient. Therefore, the LPF 802 can use components equivalent to those of the LPF 604.

[0064] The output of V S * {cos(θ 1 -θ 2 )} / 2 is obtained from the LPF 802. θ 1 -θ 2 corresponds to the above-mentioned estimated phase difference Δθ. Here, when the estimated phase difference Δθ is -90 [°] or more and less than 90 [°], the output of the LPF 802 is positive, and when the estimated phase difference Δθ is less than -90 [°] or exceeds 90 [°], the output of the LPF 802 is negative. Therefore, it is possible to determine which of the overhead line voltage phase θ 1 and the relative voltage phase θ 2 is advanced. Here, in this article, when the overhead line voltage phase θ 1 is greater than the relative voltage phase θ 2 , that is, when the estimated phase difference Δθ is positive, it is defined that the overhead line voltage phase θ 1 is advanced, and when the overhead line voltage phase θ 1 is less than the relative voltage phase θ 2 , that is, when the estimated phase difference Δθ is negative, it is defined that the overhead line voltage phase θ 1 is delayed. The sign determination unit 803 performs the above determination process by setting the range of the estimated phase difference Δθ to -180 [°] or more and +180 [°] or less. In addition, when the estimated phase difference Δθ is 0, the sign determination unit 803 determines whether the estimated phase difference Δθ is positive or negative.

[0065] The multiplication unit 804 multiplies the fixed value Δω of the frequency correction amount 0Multiply by the determination result of the multiplication sign determination unit 803, that is, either “+1” or “-1”. The output of the multiplication unit 804 is input to the switch 805. Additionally, the fixed value Δω of the frequency correction amount 0 is a positive value and is set to be the same as or less than the allowable frequency variation amount in the auxiliary power supply device 107.

[0066] In the switch 805, the frequency correction amount Δω is determined. Specifically, when the output of the LPF 802 is positive, that is, when the estimated phase difference Δθ is less than 90 [°], the output of the gain giving unit 605 is used as the frequency correction amount Δω. On the other hand, when the output of the LPF 802 is negative, that is, when the estimated phase difference Δθ exceeds 90 [°], the input of the switch 805 is switched to the - terminal side, and the output of the multiplication unit 804 is received. In this case, the frequency correction amount Δω as the output of the switch 805 becomes Δω = +ω 0 or Δω = -ω 0 . Switching the sign of the frequency correction amount Δω is to further shorten the time required for phase synchronization. Additionally, when the estimated phase difference Δθ is 90 [°], the switch 805 can receive the output of the gain giving unit 605 or the output of the LPF 802.

[0067] If the above control is regarded as the operation of the entire relative voltage operation unit 501, then when the overhead line voltage phase θ 1 is 90 [°] to 180 [°] ahead of the relative voltage phase θ 2 , it becomes an operation of increasing the frequency of the relative voltage command value V 2 * by setting the sign of the frequency correction amount Δω to positive, that is, Δω = +ω0. In addition, when the overhead line voltage phase θ 1 is 90 [°] to 180 [°] behind the relative voltage phase θ 2 , it becomes an operation of setting the sign of the frequency correction amount Δω to negative, that is, Δω = -ω 0 , thereby reducing the frequency of the relative voltage command value V 2 * .

[0068] Next, the effects brought about by using the relative voltage operation unit 501 according to the embodiment will be described. Figure 9 is a diagram for explaining the effect of shortening the time required for phase synchronization when using the relative voltage operation unit 501 according to the embodiment.

[0069] In Figure 9 , similar to Figure 7 , the horizontal axis represents the actual voltage phase difference θ 1 -θ 2, the vertical axis represents the time required for phase synchronization, that is, the time until the processing of the PLL converges and phase synchronization is completed. In addition, in Figure 9 , the solid line represents the time required for phase synchronization when using this method, and the dashed line represents the time required for phase synchronization shown as a comparative example. Here, the comparative example assumes a structure in which the function of the switching unit 820 is excluded from the structure of the relative voltage operation unit 501 shown in Figure 8 , that is, a structure that does not have the function of switching the sign of the frequency correction amount Δω according to the estimated phase difference Δθ. In addition, in Figure 9 , the meaning of the straight line indicated by the dash-dot line will be described later.

[0070] As Figure 9 a prerequisite, the overhead line voltage is 50 [Hz]. In addition, the frequency of the voltage supplied to the auxiliary power supply device 107 is allowed to be in the range of 50 ± 3 [Hz], and is set to Δω 0 = 3 × 2π [rad / s]. In addition, the gain K PLL applied by the gain imparting unit 605 is set such that K PLL = Δω 0 / V S * , so that the frequency correction amount Δω when Δθ = 90° is consistent with Δω 0 .

[0071] In addition, Figure 9 the actual voltage phase difference θ 1 -θ 2 shown on the horizontal axis of 1 is the actual voltage phase difference at the time point when the overhead line voltage V Figure 9 recovers and the switch 606 switches to the on state. In addition, in Figure 9 , the time when the actual voltage phase difference θ 1 -θ 2 is 0.1 [rad] or less is set as the phase synchronization completion time.

[0072] In the case of the comparative example, as the actual voltage phase difference θ 1 -θ 2 approaches 180 [°], the time required for phase synchronization increases sharply. In particular, at 180 [°], an infinite amount of time is required and phase synchronization cannot be achieved. In contrast, in the case of this method, even when the actual voltage phase difference θ 1 -θ 2 is 180 [°], phase synchronization can be completed within a time less than 0.4 [s].

[0073] In addition, in the above description, a structure is described in which the sign of the frequency correction amount Δω is switched based on the determination result of the symbol determination unit 803 in order to further shorten the time required for phase synchronization. Since the symbol determination unit 803 switches the sign at ±90 [°], this means that the threshold for switching the sign of the frequency correction amount Δω is ±90 [°]. On the other hand, this threshold may not be ±90 [°], for example, it may be set to ±150 [°]. The reason will be described below with reference to Figure 9 Explain the reason.

[0074] In Figure 9 , a straight line connecting point A on the dotted line shown as a comparative example to the origin (0, 0) is drawn with a single dotted line. This straight line is the tangent line of point A and is the straight line with the smallest slope among the straight lines connecting any point on the dotted line to the origin (0, 0). In addition, the actual voltage phase difference θ 1 -θ 2 corresponding to point A is approximately 157 [°]. Here, the slope of the straight line is "(time required for phase synchronization (vertical axis))" ÷ "(actual voltage phase difference (horizontal axis))", and it increases sharply at point A. The increase in the slope of the straight line means that the time required for phase synchronization becomes longer. Therefore, 150 [°] corresponding to point B close to and on the left side of point A is set as the threshold for sign switching. In addition, Figure 9 The curve shown in 1 -θ 2 is symmetric about the left and right, and the negative side of the actual voltage phase difference θ

[0075] is set to -150 [°].

[0075] Therefore, the switching unit 820 provided in the relative voltage operation unit 501 compares the absolute value of the estimated phase difference Δθ with the threshold value. When the absolute value of the estimated phase difference Δθ is greater than the threshold value and the sign of the estimated phase difference Δθ is positive, the frequency correction amount Δω is switched to a positive value. In addition, the switching unit 820 compares the absolute value of the estimated phase difference Δθ with the threshold value. When the absolute value of the estimated phase difference Δθ is greater than the threshold value and the sign of the estimated phase difference Δθ is negative, the frequency correction amount Δω is switched to a negative value.

[0076] In the above control, if the case where the sign switching threshold of the frequency correction amount Δω is ±90 [°] is compared with the case where the sign switching threshold of the frequency correction amount Δω is ±150 [°], the former can share the functions of the existing controller. Therefore, compared with the latter, the former has the effect of simplifying the control system structure. In addition, regarding Figure 9The slope of the straight line in [it] is such that the value of "(actual voltage phase difference (horizontal axis)) ÷ (time required for phase synchronization (vertical axis))" when the vertical and horizontal relationships are viewed in reverse corresponds to the difference between the average frequency in the PLL operation and the overhead line voltage frequency, that is, the average frequency correction amount in the PLL operation. Therefore, in the case of adopting the latter, it is possible to obtain the effect of suppressing an increase in the average frequency correction amount in the PLL operation and shortening the time required for phase synchronization at the same time.

[0077] Next, specific operation waveforms will be described with reference to Figures 10 to 15 the accompanying drawings. Figure 10 is a diagram showing voltage waveforms and current waveforms of main parts in a comparative example when the actual voltage phase difference is 180 [°]. Figure 11 is a diagram showing the PLL operation waveform in a comparative example when the actual voltage phase difference is 180 [°]. Figure 12 is a diagram showing voltage waveforms and current waveforms of main parts in this method when the actual voltage phase difference is 180 [°]. Figure 13 is a diagram showing the PLL operation waveform in this method when the actual voltage phase difference is 180 [°]. Figure 14 is a diagram showing voltage waveforms and current waveforms of main parts in this method when the actual voltage phase difference is 150 [°]. Figure 15 is a diagram showing the PLL operation waveform in this method when the actual voltage phase difference is 150 [°].

[0078] In Figure 10 , Figure 12 and Figure 14 in each of the figures, the waveforms of (a) overhead line voltage V 1 , (b) converter AC current, (c) received voltage of auxiliary power supply device 107, and (d) consumed current of auxiliary power supply device 107 are shown in order from top to bottom. In addition, in Figure 11 , Figure 13 and Figure 15 in each of the figures, the input signal of switch 606, synchronization determination result, (a) overhead line voltage V 1 , PLL voltage V 2p , (c) relative voltage command value V 2 * and (d) frequency waveforms of relative voltage command value V 2 * are shown in order from top to bottom.

[0079] Figure 10 and Figure 11 are simulation results in a comparative example when the actual voltage phase difference is 180 [°], Figure 12 and Figure 13 are simulation results in this method when the actual voltage phase difference is 180 [°],Figure 14 and Figure 15 are the simulation results in this method when the actual voltage phase difference is 150[°].

[0080] In Figure 11 、 Figure 13 and Figure 15 in each of their (a), the thick dashed line indicates the on signal of the switch 606, and the thick solid line indicates the synchronization determination result. In addition, in Figure 11 、 Figure 13 and Figure 15 in each of their (b), the thick dashed line indicates the overhead line voltage V 1 , and the thin solid line indicates the PLL voltage V 2p . In addition, Figure 10 、 Figure 12 and Figure 14 the overhead line voltage V 1 、 Figure 11 、 Figure 13 and Figure 15 shown in each of their (a), and the overhead line voltage V 1 and the PLL voltage V 2p shown in each of their (b) are all secondary side conversion values.

[0081] As Figure 11 (b) shows, it can be seen that in the operation of the comparative example when the actual voltage phase difference is 180[°], after the overhead line voltage V 1 recovers at time 4.5[s], even after another 0.4[s], the overhead line voltage V 1 and the PLL voltage V2p do not complete synchronization. The reason for this is that, as explained in reference Figure 7 , when the actual voltage phase difference is 180[°], it is estimated that the phase difference Δθ is substantially zero, so the output of the gain imparting unit 605 is a very small value, and the PLL cannot operate sufficiently.

[0082] On the other hand, in the operation of this method when the actual voltage phase difference is 180[°], as Figure 13 (b) shows, after the overhead line voltage V 1 recovers at time 4.5[s], the voltage phase matching between the overhead line voltage V 1 and the PLL voltage V 2p is immediately performed, and the phase synchronization is completed within approximately 0.3[s]. When the phase synchronization is completed, an on signal is sent to the switch 103. When observing Figure 12When observing the waveform of the received power voltage of the auxiliary power supply device 107 shown in (c), it can be seen that although differences in harmonic components from the converter 210 and the auxiliary power supply device 107 can be observed in the waveform before the switch 103 is turned on and after the switch 103 is turned on, voltage is always supplied. In addition, as shown in Figure 13 (d), as in the initial design, the frequency of the supplied voltage also converges within the range of 50 ± 3 [Hz].

[0083] In addition, Figures 10 to 13 in the operation example shown, synchronization is performed by increasing the frequency correction amount Δω, while in Figure 14 and Figure 15 , synchronization is performed by decreasing the frequency correction amount Δω. That is, it can be seen that if the method according to this embodiment is used, correct operation can be achieved whether the frequency correction amount Δω is increased or decreased.

[0084] In addition, the phase synchronization between the converter voltage phase and the overhead line voltage phase when a railway vehicle passes through the dead zone has been described above, but it is not limited to this example. For example, for phase synchronization during an instantaneous power outage of the overhead line, this method can also be applied and the above effects can be enjoyed.

[0085] As described above, in the power conversion device for railway vehicles according to the embodiment, the control device includes a converter control unit that controls the converter during a non-power supply period when power is not supplied from the overhead line, and supplies the regenerative power generated by the propulsion motor to the second power conversion device via the main transformer. The converter control unit includes a reference voltage calculation unit and a voltage phase estimation unit. The reference voltage calculation unit calculates a reference voltage that is a reference for current control of the converter based on the detected value of the overhead line voltage. The voltage phase estimation unit estimates the phase of the AC voltage applied to the second power conversion device during the non-power supply period based on the reference voltage. The reference voltage calculation unit includes a phase difference estimation unit and a switching unit. The phase difference estimation unit estimates the phase difference between a first phase that is the phase of a first voltage and a second phase that is the phase of a second voltage. The first voltage is the overhead line voltage detected by the voltage detector after the end of the non-power supply period. The second voltage is the AC voltage estimated by the voltage phase estimation unit based on the overhead line voltage detected by the voltage detector before the start of the non-power supply period. The switching unit switches the sign of the frequency correction amount for correcting the frequency of the second voltage based on the estimated phase difference that is the estimated value of the phase difference. According to the power conversion device for railway vehicles configured in this way, it is possible to solve the problem that when the actual voltage phase difference is large, the estimated phase difference is estimated to be smaller than the actual value, and time is required for phase synchronization. Thus, even if the overhead line voltage frequency deviates from the rated value, an increase in the time required for phase synchronization can be suppressed. In addition, the non-power supply period mentioned here may be a period including the period when the railway vehicle passes through the dead zone and the periods before and after it, or may be a period from an instantaneous power outage of the overhead line to the restoration of the instantaneous power outage.

[0086] In the above structure, when the sign of the estimated phase difference is positive, the converter control unit increases the frequency of the second voltage, and when the sign of the estimated value of the estimated phase difference is negative, the converter control unit decreases the frequency of the second voltage. In addition, the switching unit compares the absolute value of the estimated phase difference with a preset threshold value, and when the absolute value of the estimated phase difference is greater than the threshold value and the sign of the estimated phase difference is positive, switches the frequency correction amount to a positive value. In addition, the switching unit compares the absolute value of the estimated phase difference with a preset threshold value, and when the absolute value of the estimated phase difference is greater than the threshold value and the sign of the estimated phase difference is negative, switches the frequency correction amount to a negative value. This control has good compatibility with the existing control system and can be easily incorporated into the existing control system.

[0087] In addition, in the above control, the threshold value compared with the absolute value of the estimated phase difference can be set to, for example, 90 degrees or 150 degrees. If the threshold value is set to 90 degrees, the structure of the control system can be simplified. In addition, if the threshold value is set to 150 degrees, it is possible to shorten the time required for phase synchronization while suppressing an increase in the average frequency correction amount in the PLL operation.

[0088] Finally, the accompanying drawings of Figure 16 and Figure 17 will be used to describe the hardware structure for implementing the functions of the above-mentioned converter control unit 242. Figure 16 FIG. is a block diagram showing an example of the hardware structure for implementing the functions of the converter control unit 242 in the embodiment. Figure 17 FIG. is a block diagram showing another example of the hardware structure for implementing the functions of the converter control unit 242 in the embodiment.

[0089] When implementing some or all of the functions of the converter control unit 242 in the present embodiment, as Figure 16 shown, it can be configured to include a processor 300 that performs operations, a memory 302 that stores a program read by the processor 300, and an interface 304 that performs signal input and output.

[0090] The processor 300 is an arithmetic unit. The processor 300 can be an arithmetic unit such as a microprocessor, a microcomputer, a CPU (Central Processing Unit), or a DSP (Digital Signal Processor). In addition, examples of the memory 302 include non-volatile or volatile semiconductor memories such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable ROM), EEPROM (registered trademark) (Electrically Erasable Programmable Read Only Memory), magnetic disks, floppy disks, optical disks, compact disks, mini disks, and DVDs (Digital Versatile Discs). Additionally, the memory 302 can combine multiple storage devices such as RAM and EEPROM.

[0091] The memory 302 stores a program for executing the functions of the converter control unit 242 in the embodiment. The processor 300 can execute the program stored in the memory 302 by sending and receiving necessary information via the interface 304, and perform the above processing with reference to the tables stored in the memory 302. The operation results of the processor 300 can be stored in the memory 302.

[0092] In addition, when implementing some of the functions of the converter control unit 242 in the embodiment, Figure 17The processing circuit 303 shown. The processing circuit 303 is a single circuit, a composite circuit, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. Information input to the processing circuit 303 and information output from the processing circuit 303 can be obtained via the interface 304.

[0093] In addition, part of the processing in the converter control unit 242 can be implemented by the processing circuit 303, and the processing not implemented in the processing circuit 303 can be implemented by the processor 300 and the memory 302.

[0094] In addition, the structure shown in the above embodiments represents an example, and it can be combined with other known technologies, or a part of the structure can be omitted or changed without departing from the gist of the present invention. Reference Numeral Explanation

[0095] 100 Overhead line, 101 Power receiving unit, 102 ACPT, 103 Switch, 104 Main transformer, 105 Main conversion device, 106 Propulsion motor, 107 Auxiliary power supply device, 141 Primary winding, 142 Secondary winding, 143 Tertiary winding, 210 Converter, 211, 231 Primary side terminals, 212, 232 Secondary side terminals, 213 Current sensor, 220 Smoothing capacitor, 221 Voltage sensor, 230 Inverter, 240 Control device, 242 Converter control unit, 244 Inverter control unit, 300 Processor, 302 Memory, 303 Processing circuit, 304 Interface, 501 Relative voltage operation unit, 502 Voltage phase estimation unit, 503 Current control unit, 504 Voltage command operation unit, 505 Converter drive signal generation unit, 601, 605 Gain assignment units, 602 Cosine operation unit, 603, 610, 801, 804 Multiplication units, 604, 802 LPF, 606, 611, 805 Switches, 607 Addition unit, 608 Integration unit, 609 Sine operation unit, 612 BPF, 803 Sign determination unit, 810 Phase difference estimation unit, 820 Switching unit.

Claims

1. A power conversion device for a railway vehicle, which is mounted on a railway vehicle. The railway vehicle comprises: A main transformer with a primary winding connected to an overhead line via a current collector; A switch for electrically disconnecting or connecting the main transformer and the overhead line; And a voltage detector disposed between the overhead line and the switch for detecting the overhead line voltage applied from the overhead line. The power conversion device for a railway vehicle includes: A first power conversion device connected to the secondary winding of the main transformer, having a converter for converting the AC voltage applied through the main transformer into a DC voltage, and connected to a propulsion motor for driving the railway vehicle; A second power conversion device connected to the tertiary winding of the main transformer for supplying power to auxiliary equipment mounted on the railway vehicle; And a control device for controlling the operations of the switch, the first power conversion device, and the second power conversion device. The power conversion device for a railway vehicle is characterized in that The control device includes a converter control section that controls the converter during a non-power supply period when power is not supplied from the overhead line, and performs control to supply the regenerative power generated by the propulsion motor to the second power conversion device via the main transformer. The converter control section includes: A reference voltage calculation section that calculates a reference voltage that serves as a reference for current control of the converter based on the detected value of the overhead line voltage; And A voltage phase estimation section that estimates the phase of the AC voltage applied to the second power conversion device during the non-power supply period based on the reference voltage. The reference voltage calculation section includes: A phase difference estimation section that estimates the phase difference between a first phase and a second phase. The first phase is the phase of the first voltage when the overhead line voltage detected by the voltage detector after the end of the non-power supply period is set as the first voltage, and the second phase is the phase of the second voltage when the AC voltage estimated by the voltage phase estimation section based on the overhead line voltage detected by the voltage detector before the start of the non-power supply period is set as the second voltage; And A switching section that switches the sign of a frequency correction amount for correcting the frequency of the second voltage based on the estimated phase difference that is the estimated value of the phase difference.

2. The power conversion device for a railway vehicle according to claim 1, characterized in that The non-power supply period is a period including the period when the railway vehicle passes through a dead zone and the periods before and after it.

3. The power conversion device for a railway vehicle according to claim 1, characterized in that The non-power supply period is a period from an instantaneous power outage of the overhead line to the restoration of the instantaneous power outage.

4. The power conversion device for a railway vehicle according to any one of claims 1 to 3, characterized in that When the sign of the estimated phase difference is positive, the converter control section increases the frequency of the second voltage. When the sign of the estimated value of the estimated phase difference is negative, the frequency of the second voltage is decreased.

5. The power conversion device for a railway vehicle according to any one of claims 1 to 4, characterized in that the switching unit compares the absolute value of the estimated phase difference with a preset threshold value, and when the absolute value is greater than the threshold value and the sign of the estimated phase difference is positive, the frequency correction amount is switched to a positive value.

6. The power conversion device for a railway vehicle according to any one of claims 1 to 4, characterized in that the switching unit compares the absolute value of the estimated phase difference with a preset threshold value, and when the absolute value is greater than the threshold value and the sign of the estimated phase difference is negative, the frequency correction amount is switched to a negative value.

7. The power conversion device for a railway vehicle according to claim 5 or 6, characterized in that the threshold value is 90 degrees.

8. The power conversion device for a railway vehicle according to claim 5 or 6, characterized in that the threshold value is 150 degrees.

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