Power conversion device for railroad car

Abstract

In the case of this power conversion device for a railroad car, a converter control section (242) provided in a control device (240) comprises: a counter voltage computation unit (501) for computing a counter voltage to be used as a reference for current control of a converter (210) on the basis of a detected value of an overhead-line voltage; and a voltage phase estimation unit (502) for estimating the phase of an alternating-current voltage to be applied to an auxiliary power supply device (107) during an unpowered period on the basis of the counter voltage. The counter voltage computation unit (501) comprises: a phase difference estimation part (810) for estimating a phase difference between a first phase, that is, the phase of a first voltage which is an overhead-line voltage detected by an ACPT (102) after the unpowered period is ended, and a second phase, that is, the phase of an alternating-current second voltage estimated by the voltage phase estimation unit (502) on the basis of an overhead-line voltage detected by the ACPT (102) before the start of the unpowered period; and a switching part (820) for switching the sign of a frequency correction amount by which to correct the frequency of the second voltage on the basis of the estimated phase difference, that is, the value estimated for the phase difference.

Description

Power conversion equipment for railway vehicles

[0001] The present disclosure relates to a power conversion device for a railway vehicle that runs on AC power supplied from an AC overhead line.

[0002] On AC-electrified railway lines, the range of power supply from a single substation is limited, and the voltage phase of AC power varies from substation to substation. For this reason, railway lines have sections where power cannot be supplied at the boundaries of the power supply sections. These sections are called "dead sections." Therefore, when a railway vehicle running on AC power supplied from an AC overhead line passes through a dead section, the power supply from the AC overhead line is interrupted. Meanwhile, at this time, regenerative power from the traction motor used to drive the railway vehicle can be supplied to the auxiliary machinery mounted on the railway vehicle, allowing the power supply to the auxiliary machinery to continue as during normal operation. This operation is called "pump-back." The term "auxiliary machinery" refers to the equipment mounted on the railway vehicle that receives power, other than the traction motor. Power to the auxiliary machinery is supplied by a power conversion device called an auxiliary power supply unit (APS).

[0003] When the power supply from the overhead line resumes after passing the dead section, the circuit breaker at the power receiving section is closed and the system switches back to normal overhead line power supply. If the overhead line is an AC overhead line, the voltage phase must be matched between the voltage applied to the main transformer before the switchover and the overhead line voltage applied after the switchover to prevent excessive current from flowing, and the circuit breaker must be closed accordingly. In particular, in a circuit configuration in which the auxiliary power supply unit is connected to the tertiary winding of the main transformer, the phase must be matched while continuing to apply AC voltage to the main transformer.

[0004] Against the above technical background, Patent Document 1 below discloses a technology for directly determining the overhead line voltage phase, which is the phase of the overhead line voltage, and increasing the frequency so that the converter voltage phase catches up with this overhead line voltage phase, thereby achieving phase synchronization between the converter voltage and the overhead line voltage.

[0005] Patent No. 6510060

[0006] However, the above-mentioned Patent Document 1 does not disclose a specific method for directly determining the overhead line voltage phase. Furthermore, the method of directly calculating the overhead line voltage phase, as in Patent Document 1, has the problem that when the overhead line voltage frequency deviates from the rated value, phase detection is difficult and the phase synchronization time required to align the converter voltage phase with the overhead line voltage phase becomes long.

[0007] The present disclosure has been made in consideration of the above, and aims to provide a power conversion device for a railway vehicle that can suppress an increase in the time required for phase synchronization even if the overhead line voltage frequency deviates from the rated value.

[0008] To solve the above-mentioned problems and achieve the object, a railway vehicle power conversion device according to the present disclosure is mounted on a railway vehicle including a main transformer, a switch, and a voltage detector. The main transformer has a primary winding connected to an overhead line via a power receiving unit, the switch electrically connects or disconnects the main transformer from the overhead line, and the voltage detector is provided between the overhead line and the switch and detects the overhead line voltage applied from the overhead line. The railway vehicle power conversion device includes a first power conversion device, a second power conversion device, and a control device. The first power conversion device is connected to a secondary winding of the main transformer and includes a converter that converts AC voltage applied via the main transformer to DC voltage, and is connected to a traction motor for driving the railway vehicle. The second power conversion device is connected to a tertiary winding of the main transformer and supplies power to auxiliary machinery mounted on the railway vehicle. The control device controls the operation of the switch and the first and second power conversion devices. The control device includes a converter control unit that controls the converter to supply regenerative power generated by the traction motor to the second power conversion device via the main transformer during a power-loss period when no power is supplied from the overhead line. 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 a detected value of the overhead line voltage. The voltage phase estimation unit estimates the phase of the AC voltage to be applied to the second power conversion device during the power-loss 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 a phase difference between a first phase that is the phase of the first voltage and a second phase that is the phase of the second voltage. The first voltage is the overhead line voltage detected by the voltage detector after the end of the power-loss 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 power-loss 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, which is an estimate of the phase difference.

[0009] The railway vehicle power conversion device according to the present disclosure has the advantage of being able to suppress an increase in the time required for phase synchronization even if the overhead line voltage frequency deviates from the rated value.

[0010] FIG. 1 is a diagram showing an example of the configuration of an electrical system of a railway vehicle system including a railway vehicle power conversion device according to an embodiment; FIG. 2 is a diagram showing an example of the configuration of the main converter shown in FIG. 1; FIG. 3 is a diagram explaining the energy flow during normal operation in a railway vehicle power conversion device according to an embodiment; FIG. 4 is a diagram explaining the energy flow during a non-powered period in a railway vehicle power conversion device according to an embodiment; FIG. 1 shows voltage waveforms and current waveforms of essential parts in a comparative example when the real voltage phase difference is 180°. FIG. 2 shows PLL operation waveforms in a comparative example when the real voltage phase difference is 180°. FIG. 3 shows voltage waveforms and current waveforms of essential parts in the present system when the real voltage phase difference is 180°. FIG. 4 shows PLL operation waveforms in the present system when the real voltage phase difference is 180°. FIG. 5 shows voltage waveforms and current waveforms of essential parts in the present system when the real voltage phase difference is 150°. FIG. 6 shows PLL operation waveforms in the present system when the real voltage phase difference is 150°.

[0011] A railcar power conversion device according to an embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings. Note that in the following description, physical connection and electrical connection will not be distinguished from each other, and the term "connection" will be used interchangeably. In other words, the term "connection" encompasses both a direct connection between components and an indirect connection between components via other components.

[0012] Embodiment. FIG. 1 is a diagram showing an example of the configuration of an electrical system of a railway vehicle system including a railway vehicle power conversion device according to an embodiment. The railway vehicle system according to the embodiment is configured with a power receiving unit 101, an ACPT (Alternating Current Potential Transformer) 102, which is a voltage detector, a switch 103, a main transformer 104, a main converter 105, a traction motor 106, and an auxiliary power supply 107. Note that FIG. 1 shows a configuration with four main converters 105 and four traction motors 106, but this is just an example and the number of motors may be different. Also, FIG. 1 shows a configuration in which one traction motor 106 is connected to one main converter 105, but a configuration in which multiple traction motors 106 are connected to one main converter 105 may also be used. 1 shows a configuration in which one auxiliary power supply unit 107 is connected to the main transformer 104, but a configuration in which multiple auxiliary power supplies 107 are connected to the main transformer 104 may also be used. In addition, in FIG. 1, the main converter 105 and the auxiliary power supplies 107 constitute a power conversion device for a railway vehicle according to an embodiment.

[0013] The power receiving unit 101 is a device that allows the railway vehicle to receive AC power from the overhead line 100. Examples of the power receiving unit 101 include a pantograph, a current collecting shoe, etc. It is assumed that power is supplied to the railway vehicle by a pantograph attached to the top of the railway vehicle, but a third rail installed next to the tracks may also be used.

[0014] The switch 103 is a device that electrically switches between the main transformer 104 and the overhead line 100. One example of the switch 103 is a circuit breaker, and a vacuum circuit breaker (VCB) is often used for railway vehicles. Note that any device that can electrically switch between the main transformer 104 and the overhead line 100, i.e., disconnect and connect, does not have to be a circuit breaker.

[0015] The ACPT 102 is a device that measures the power receiving voltage of the power receiving unit 101. The ACPT 102 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. The secondary winding 142 is connected to the main converter 105, and the tertiary winding 143 is connected to the auxiliary power supply 107. An overhead line voltage is applied to the primary winding 141, and a voltage determined by the turns ratio between the primary winding 141 and the secondary winding 142 and the tertiary winding 143 is generated in the primary winding 141. The number of secondary windings 142 is equal to the number of main converters 105, and the number of tertiary windings 143 is equal to the number of auxiliary power supplies 107. Basically, each winding is connected to each device one-to-one; however, a configuration in which one winding is connected to multiple devices via a reactor may also be used. The voltage applied to the primary winding 141 is a reference voltage that serves as a reference for current control of the converter 210. In this paper, this reference voltage is called the "counter voltage." In this paper, this counter voltage is calculated.

[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 traction motor 106 and converts the DC voltage applied from the converter 210 into a drive voltage for the traction motor 106 and applies it to the traction motor 106. In this document, the main conversion device 105 may be referred to as the "first power conversion device."

[0018] The traction motor 106 is a motor for driving the railway vehicle. The railway vehicle runs using driving force obtained from the rotation of the traction motor 106. The railway vehicle also accelerates or decelerates using torque generated by the traction motor 106.

[0019] The auxiliary power supply 107 is connected to the tertiary winding 143 of the main transformer 104 and supplies power to the aforementioned auxiliary equipment. Examples of the auxiliary equipment include interior lighting, door opening and closing devices, air conditioning equipment, safety equipment, compressors, batteries, and control power supplies. In this paper, the auxiliary power supply 107 is sometimes referred to as the "second power conversion device."

[0020] Fig. 2 is a diagram showing an example of the configuration of the main converter 105 shown in Fig. 1. The main converter 105 includes a converter 210, a smoothing capacitor 220, an inverter 230, and a control device 240. The control device 240 also includes a converter control unit 242 and an inverter control unit 244.

[0021] The converter 210 includes a primary terminal 211 and a secondary terminal 212. The converter 210 can convert between a single-phase AC voltage applied to the primary terminal 211 and a DC voltage applied to the secondary terminal 212. This operation is controlled by a converter control unit 242. The converter 210 controls the power supplied to the inverter 230 by adjusting the voltage at the primary terminal 211. A current sensor 213 is disposed at one of the primary terminals 211. The current sensor 213 detects the current flowing through the primary side of the converter 210. Note that FIG. 2 illustrates a three-level converter having three secondary terminals 212 and capable of outputting three types of potential to the secondary side, but this example is not limiting. The number of secondary terminals 212 may be two, four, or more. A configuration with two secondary terminals 212 is called a two-level converter.

[0022] The inverter 230 includes a primary terminal 231 and a secondary terminal 232. The inverter 230 can convert between a DC voltage applied to the primary terminal 231 and an AC voltage applied to the secondary terminal 232. This operation is controlled by an inverter control unit 244. The inverter 230 controls the output torque of the propulsion motor 106 by adjusting the voltage at the secondary terminal 232. If the propulsion motor 106 is a three-phase AC motor, the voltage output to the secondary terminal 232 will be a three-phase AC voltage. Note that FIG. 2 illustrates a two-level inverter having two primary terminals 231 and capable of outputting two types of potential to the primary side, but this example is not limiting. The number of primary terminals 231 may be three or more. A configuration with three primary terminals 231 is called a three-level inverter.

[0023] The smoothing capacitor 220 is connected between the secondary terminal 212 of the converter 210 and the primary terminal 231 of the inverter 230, and has the function of suppressing fluctuations in DC voltage. If the converter 210 and the inverter 230 are both configured as two levels, only one smoothing capacitor 220 may be provided. A voltage sensor 221 is also arranged in parallel with the smoothing capacitor 220. The voltage sensor 221 detects the capacitor voltage, which is the voltage across the smoothing capacitor 220.

[0024] Fig. 3 is a diagram illustrating the energy flow in a railway vehicle power conversion device according to an embodiment during normal operation. Fig. 4 is a diagram illustrating the energy flow in a railway vehicle power conversion device according to an embodiment during a power-off period. Note that normal operation refers to a state in which power from the overhead line 100 is normally applied to the main transformer 104. The power-off period is a concept that includes a period in which the railway vehicle actually passes through a dead section, as well as periods before and after that in which the switch is in an open state. In other words, the power-off period is a period in which the main transformer 104 and the overhead line 100 are electrically disconnected, and no power is supplied to the main transformer 104 from the overhead line 100.

[0025] Under normal circumstances, the power required to drive the railway vehicle is supplied to the main converter 105 and auxiliary power supply 107 via the power receiving unit 101, the switch 103, and the main transformer 104. The main converter 105 converts the supplied power into drive power for the propulsion motor 106, thereby driving the propulsion motor 106. The auxiliary power supply 107 converts the supplied power into drive power for the auxiliary machinery, thereby operating the auxiliary machinery.

[0026] During the power-off period, power cannot be supplied from the overhead line 100. Therefore, the converter control unit 242 provided in the control device 240 performs pump-back, which regenerates the kinetic energy of the traction motor 106 and supplies the regenerated power to the auxiliary power supply 107 via the traction motor 105 and the traction transformer 104. In the following description, any reference to the traction motor 105 refers to the traction motor 105 performing pump-back. Note that one traction motor 105 performs pump-back for each traction transformer 104. By having one traction motor 105 perform pump-back, it is possible to prevent the regenerative power supplied to the traction motor 104 from becoming unstable. The traction motor 105 performing pump-back may be predetermined or may be designated by a train information management device that manages train information. The power-off period associated with passing through a dead section is short, and the amount of power consumed by the auxiliary power supply 107 during this period is sufficiently smaller than the kinetic energy of the traction motor 106 and the railway vehicle. Therefore, even if only one main converter 105 performs pump back, it is possible to avoid a situation in which the train suddenly decelerates.

[0027] Fig. 5 is a time chart illustrating the operation during pump-back in this embodiment. The horizontal axis of Fig. 5 represents time. The vertical axis of Fig. 5 shows, from the top to the bottom, the waveform detected by the ACPT 102, the dead section passage warning signal, the torque pattern, the pump-back status signal, the status signal of the switch 103, and the voltage waveform used for converter control.

[0028] Before the railway vehicle passes through a dead section, a dead section passage warning signal is output. Specifically, in the example of FIG. 5 , the dead section passage warning signal is output at time t1, and the output of the dead section passage warning signal is stopped at time t10. Regeneration begins at time t2, and pump-back begins at time t3. Switch 103 is opened at time t4, and remains open until time t11. The period from time t5 to time t6 is the period during which the railway vehicle actually passes through the dead section. During the period from time t7 to time t8, control is performed to match the output voltage waveform of converter 210 to the waveform detected by ACPT 102. Pump-back ends at time t9, and the system switches from regeneration to powering at time t12.

[0029] Next, the behavior of the main transformer 104 and the main conversion device 105 will be described with reference to the time chart of Figure 5. First, when power is supplied from the overhead line 100, the converter 210 operates to maintain a constant capacitor voltage. The main transformer 104 outputs a single-phase AC voltage to the primary terminal 211 of the converter 210 so that the converter 210 can receive the necessary power. The converter 210 outputs a DC voltage to the secondary terminal 212 so that the smoothing capacitor 220 can follow the voltage as commanded. Meanwhile, the inverter 230 outputs a voltage to the secondary terminal 232 so that the traction motor 106 can output torque as commanded.

[0030] At time t1, a dead section passage warning signal is output. Upon receiving this signal, the inverter 230 reduces the powering torque and then stops supplying current to the traction motor 106. This causes the traction motor 106 to rotate by inertia, and the railway vehicle enters a coasting state. When the operation switches to pump-back at time t3, the inverter 230 operates to regenerate from the traction motor 106 the power required to maintain the capacitor voltage. After the start of pump-back, when the regenerated power from the main converter 105 and the power consumption of the auxiliaries connected to the auxiliary power supply 107 nearly match, the current flowing through the switch 103 approaches zero. This makes it possible to open the switch 103 at time t4.

[0031] During the period from time t5 to time t6 when the train is actually passing through the dead section, the overhead line voltage cannot be measured. Therefore, at time t4 when the status signal of switch 103 is turned OFF, i.e., at time t4 before time t5, control is switched to one that does not reference the overhead line voltage. Specifically, converter 210 outputs a voltage of a constant amplitude and frequency to primary terminal 211 without reference to the overhead line voltage. Here, the power supplied by converter 210 depends on the load of auxiliary power supply 107, so capacitor voltage cannot be controlled. Therefore, capacitor voltage control at this time is performed by inverter control unit 244. Inverter control unit 244 controls inverter 230 so that the torque command to traction motor 106 is the amount of regenerative torque required to obtain the power required to maintain capacitor voltage. Control that does not reference the overhead line voltage continues until time t7, after the train has passed through the dead section.

[0032] After time t6, when the railcar passes through the dead section, ACPT 102 resumes measuring the overhead line voltage. However, because the overhead line voltage and the voltage generated by converter 210 are out of phase, closing switch 103 at this point could result in an excessively large inrush current flowing through main transformer 104. To prevent this excessive current, converter 210 controls the voltage it generates to gradually match the waveform detected by ACPT 102. Specifically, while continuing to supply power to auxiliary power supply 107, converter 210 gradually changes the frequency of the generated voltage so that the phase of the generated voltage is synchronized with the phase of the overhead line voltage. FIG. 5 shows an example in which the phases of the generated voltage and the overhead line voltage are synchronized at time t8, pump-back ends at a subsequent time t9, and switch 103 is closed at a subsequent time t11. After time t11, power supply from the overhead line 100 is resumed, the converter 210 returns to DC voltage control, and the inverter 230 returns to motor torque control.

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

[0034] 6 is a block diagram showing an example of the configuration of converter control unit 242 according to the embodiment. As shown in FIG. 6 , converter control unit 242 according to the embodiment includes an opposite 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 counter voltage calculation unit 501 calculates the overhead line voltage V １ Based on this, the counter voltage V ２ The counter voltage command value V ２ ＊ When the switch 103 is closed, V １ =V ２ ＊ However, when the switch 103 is open, the voltages are essentially different.

[0036] The voltage phase estimation unit 502 estimates the counter voltage command value V ２ ＊ Based on this, the overhead line voltage V １ The estimated voltage phase θ Ｓ The counter voltage command value V ２ ＊ is a single-phase sine wave, and the voltage phase estimation unit 502 normally calculates V １ =V ２ ＊ The counter voltage command value V ２ ＊ Estimated voltage phase θ based on Ｓ Specifically, the voltage phase estimation unit 502 calculates the counter voltage command value V ２ ＊ is regarded as a sine wave, and the counter voltage command value V ２ ＊The timing at which the instantaneous voltage of V changes from negative to positive is detected, and the timing is set to 0° of the phase. ２ ＊ is required to be a sine wave with little ripple.

[0037] The current control unit 503 normally controls the capacitor voltage V ｄｃ The command value is the capacitor voltage command value V ｄｃ ＊ During pump-back, the output voltage is corrected to follow the counter voltage V ２ is the counter voltage command value V ２ ＊ Specifically, the current control unit 503 performs output voltage correction to make the output voltage follow the load power P ｍ and the capacitor voltage V detected by the voltage sensor 221. ｄｃ Based on the detected value of the capacitor voltage V ｄｃ is the capacitor voltage command value V ｄｃ ＊ Then, the current control unit 503 calculates the current amplitude required to make the voltage follow the calculated current amplitude and the estimated voltage phase θ output from the voltage phase estimation unit 502. Ｓ Based on this, the voltage drop V in the main transformer 104 ｔｒ On the other hand, during pump-back, the current control unit 503 calculates the current I flowing on the primary side of the converter 210. Ｓ The current sensor 213 detects the current I Ｓ Based on the detected value of ｔｒ Calculate the following.

[0038] The voltage command calculation unit 504 calculates the counter voltage command value V ２ ＊ and the voltage drop V across the main transformer 104. ｔｒ Based on this, the primary side voltage command V ａｃ ＊ Specifically, the voltage command calculation unit 504 calculates the counter voltage command value V ２ ＊ Voltage drop V ｔｒ By subtractingａｃ ＊ Calculate the following.

[0039] The converter drive signal generator 505 generates a voltage command V ａｃ ＊ , estimated voltage phase θ Ｓ and the capacitor voltage V ｄｃ Based on the detected value of ｃ The generated switching command S ｃ to the converter 210. Although not shown, the converter 210 includes a plurality of switching elements connected in a bridge configuration. ｃ is a command to turn on or off each of the multiple switching elements at a desired timing. ｃ The switching command S can be generated using a known control method, for example, a PWM method. ｃ As a result, a voltage command V ａｃ ＊ A voltage according to the voltage is output.

[0040] Next, the problems with the conventional method will be described. As described above, the counter voltage calculation unit 501 calculates the overhead line voltage V １ Based on this, the counter voltage V ２ The counter voltage command value V ２ ＊ The counter voltage command value V ２ ＊ A PLL (Phase Locked Loop) is generally used to calculate the phase difference between the input signal and the output signal. A PLL, also known as a phase-locked loop, is a method for calculating a desired phase by feedback control that matches the phase difference between the input signal and the output signal. The railway vehicle power conversion device of the present disclosure also uses a PLL, but the conventional method has the following problems. FIG. 7 is a diagram illustrating the conventional method using a PLL.

[0041] 7, the sine wave shown by the solid line is the curve used for phase estimation. The horizontal axis represents the actual voltage phase difference θ １ -θ ２The vertical axis represents the estimated phase difference Δθ in the conventional method. The dashed line represents the difference between the estimated phase difference Δθ and the actual voltage phase difference θ. １ -θ ２ In the phase estimation control, the difference between the actual voltage phase difference θ and the dashed line appears as an error component of the estimated phase difference Δθ. １ -θ ２ When the value of is small, (θ １ -θ ２ ) ≒ sin(θ １ -θ ２ ), and the estimated phase difference Δθ is calculated using sin(θ １ -θ ２ However, as shown in FIG. １ -θ ２ and sin(θ １ -θ ２ ) is the actual voltage phase difference θ １ -θ ２ The actual voltage phase difference θ １ -θ ２ When the value of θ is large, the estimated phase difference Δθ is estimated to be smaller than the actual value, which causes a problem that it takes time to synchronize the phase. １ -θ ２ When the absolute value of sin(θ １ -θ ２ )=0, the PLL does not function sufficiently, and there is a fatal problem that the voltage phase cannot be corrected.

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

[0043] Next, the operation of the counter voltage calculation unit 501 shown in Fig. 8 will be described. First, the gain applying unit 601 calculates the overhead line voltage V １ As a result, a gain N is applied to the voltage V ｂ The voltage value of is converted to a voltage equivalent to that of the secondary winding 142 of the main transformer 104. The gain N is determined 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 cos θ using the current voltage phase θ generated inside the counter voltage calculation unit 501. This process corresponds to the process of advancing the voltage waveform by 90° and generating a voltage waveform with a peak value of ±1. Here, the current voltage phase θ is calculated based on the angular frequency ω ０ and the phase θ at time 0 [s] seconds ２ Further, the voltage V output from the gain applying unit 601 can be expressed by the following equation (1). ｂ is the frequency ω ０ and the phase θ at time 0 [s] １ Using the above, it is expressed by the following equation (2).

[0045]

[0046] In the above formula (2), V Ｓ ＊ is the overhead line voltage V １ The multiplication unit 603 multiplies the output of the gain applying unit 601 by the output of the cosine calculation unit 602, and the multiplication result is expressed by the following equation (3).

[0047]

[0048] The right side of the above equation (3) is the sum of a voltage component that changes with time and a voltage component that pulsates at twice the angular frequency of the voltage. For this reason, the LPF 604 is provided to leave only the former component and remove the latter component. The transfer function of the LPF 604 is set, for example, as shown in the following equation (4). If the LPF 604 set in this way is used, the angular frequency can be reduced by 2ω ０ The components can be sufficiently removed.

[0049]

[0050] From LPF 604, V Ｓ ＊ {sin(θ １ -θ ２ As mentioned above, in the conventional method, the output of θ １ and θ ２ Assuming that the difference between Ｓ ＊ (θ １ -θ ２ ) / 2”.

[0051] The gain applying unit 605 applies a gain K ＰＬＬ is applied. Through this processing, the output of the gain applying unit 605 is converted into a 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 behavior when the frequency correction amount Δω is used will be described. When the frequency correction amount Δω is used, the voltage V ｂ For example, the frequency of the overhead line voltage V １The voltage phase of the overhead line voltage V １ The estimated voltage phase θ Ｓ If it is ahead of ｂ By increasing the frequency of the estimated voltage phase θ Ｓ is the overhead line voltage V １ On the other hand, the overhead line voltage V １ The voltage phase of the estimated voltage phase θ Ｓ If it is delayed, the voltage V ｂ By lowering the frequency of the estimated voltage phase θ Ｓ is the overhead line voltage V １ The behavior is such that the voltage phase is caught up with.

[0053] Switch 606 is fixed ON under normal conditions, turned OFF during pump-back, and turned back ON when the electric power passes through a dead section and overhead line power supply is resumed. Therefore, the frequency correction amount Δω is input to switch 606 under normal conditions, and 0 is input to switch 606 during pump-back. As a result, in the control system, when switch 606 is ON, the PLL works, and when switch 606 is OFF, the PLL does not work and a fixed frequency voltage is output to primary side terminal 211.

[0054] The adder 607 calculates the rated angular frequency ω, which is the rated frequency of the overhead line 100 multiplied by 2π. ０ A frequency correction amount Δω or 0 is added to this, 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 terminal 211 of the converter 210. Commonly used rated frequencies for AC power lines electrified by AC are 16.7, 25, 50, 60 Hz, etc.

[0055] Integrator 608 integrates the output of adder 607 and outputs the integrated value as the above-mentioned voltage phase θ to cosine calculator 602 and sine calculator 609. Here, under normal circumstances, switch 606 is controlled to be ON, so that the overhead line voltage phase is stored in integrator 608. Furthermore, during periods when power is not being fed, the phase changes at the rated angular frequency based on the overhead line voltage phase stored in integrator 608, and after passing through a dead section, PLL processing works again, resulting in a behavior that approaches the overhead line voltage phase.

[0056] In the sine calculation unit 609, a sine value sin θ is calculated using the voltage phase θ. In the multiplication unit 610, the overhead line voltage V １ The rated voltage amplitude V Ｓ ＊ is multiplied by the output of the sine calculation unit 609, and the multiplication result is the PLL voltage V ２ｐ It is said that.

[0057] The switch 611 is normally fixed to OFF, is turned ON during a non-powered period, and is returned to OFF after passing through a dead section. Here, since the switch 103 is normally closed, the voltage V output from the gain applying unit 601 is ｂ is the counter voltage command value V ２ ＊ On the other hand, during the non-powered period, the PLL voltage V ２ｐ is the counter voltage command value V ２ ＊ It is used as the signal on which the

[0058] Finally, the output of the switch 611 is input to the BPF 612, which extracts the fundamental wave component and outputs the counter voltage command value V ２ ＊ The output is the overhead line voltage V １ Since harmonics resulting from the operation of the converter 210 are superimposed on the inverter 211, the inverter 211 is provided to remove the superimposed harmonic components.

[0059] The timing at which the switch 611 is turned from ON to OFF is determined by the counter voltage command value V ２ ＊The timing is set to be after the timing when the phase of the counter voltage command value V1 coincides with the phase of the overhead line voltage V1 and after the switch 103 is turned on. Note that even if the switch 611 is turned off after the switch 103 is turned on, the counter voltage command value V ２ ＊ Since the phase of the voltage V matches the phase of the overhead line voltage V, the opposing voltage command value V ２ ＊ does not change significantly.

[0060] Here, a method for determining whether phase synchronization has been completed will also be described. ２ ＊ is converted into a sine wave consisting of only the fundamental wave component with almost no distortion by the processing of the BPF 612, so the sign changes every half cycle of the fundamental wave. １ If the instantaneous voltage is below a specified value, it is determined that phase synchronization is complete. １ The slope of 、 Counter voltage command value V ２ ＊ If the difference between the slope of the phase shift signal and the slope of the phase shift signal is equal to or smaller than a specified value, it may be determined that phase synchronization has been completed. The specified value for this determination may be determined based on the amount of inrush current allowed in the main transformer 104.

[0061] The following describes the operation of the switching unit 820, which has not been described above, in the counter voltage calculation unit 501. First, the multiplication unit 801 multiplies the output of the gain applying unit 601 by the output of the sine calculation unit 609, and the multiplication result is expressed by the following equation (5).

[0062]

[0063] The right side of the above equation (5) is the difference between the voltage component that changes over time and the voltage component that pulsates at twice the angular frequency of the voltage, and the LPF 802 leaves only the former component and removes the latter component. The LPF 802, like the LPF 604, has an angular frequency of 2ω ０ Therefore, the LPF 802 may be equivalent to the LPF 604.

[0064] From LPF802, V ｓ ＊ {cos(θ １ -θ ２ )} / 2 output is obtained. １ -θ ２ corresponds to the above-mentioned estimated phase difference Δθ. Here, when the estimated phase difference Δθ is equal to or greater than −90° and less than 90°, the output of the LPF 802 is a positive value, and when the estimated phase difference Δθ is less than −90° or more than 90°, the output of the LPF 802 is a negative value. Therefore, the overhead line voltage phase θ １ and the opposing voltage phase θ ２ Which phase is leading can be determined from the sign of the output result of the LPF 802. １ is the opposing voltage phase θ ２ When the estimated phase difference Δθ is greater than θ, that is, when the estimated phase difference Δθ is positive, the overhead line voltage phase θ １ is defined as leading, and the overhead line voltage phase θ １ is the opposing voltage phase θ ２ When the estimated phase difference Δθ is negative, the overhead line voltage phase θ １ is defined as being delayed. The sign determination unit 803 performs the above determination process by setting the range of the estimated phase difference Δθ to be equal to or greater than −180° and equal to or less than +180°. When the estimated phase difference Δθ is 0, the sign determination unit 803 determines whether the phase difference is positive or negative.

[0065] The multiplication unit 804 multiplies the fixed value Δω of the frequency correction amount by ０ is multiplied by the result of the determination by the sign determination unit 803, that is, by either "+1" or "-1". The output of the multiplication unit 804 is input to the switch 805. Note that the fixed value Δω of the frequency correction amount is ０ is a positive value and is set to be equal to or less than the amount of frequency fluctuation allowed in the auxiliary power supply 107.

[0066] The switch 805 determines the frequency correction amount Δω. 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 applying 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 negative terminal side, and the output of the multiplier 804 is accepted. In this case, the frequency correction amount Δω, which is the output of the switch 805, is expressed as Δω = +ω depending on the determination result of the sign determining unit 803. ０ , or Δω=-ω ０ The sign of the frequency correction amount Δω is switched in order to shorten the time required for phase synchronization. When the estimated phase difference Δθ is 90°, the switch 805 may accept either the output of the gain applying unit 605 or the output of the LPF 802.

[0067] When the above-mentioned control is viewed as the overall operation of the counter voltage calculation unit 501, the overhead line voltage phase θ １ is the opposing voltage phase θ ２ Therefore, if the advance is in the range of 90° to 180°, the sign of the frequency correction amount Δω is plus, that is, Δω=+ω ０ As the counter voltage command value V ２ ＊ In addition, the overhead line voltage phase θ １ is the opposing voltage phase θ ２ Therefore, if the delay is in the range of 90° to 180°, the sign of the frequency correction amount Δω is negative, that is, Δω=-ω ０ As the counter voltage command value V ２ ＊ This results in a behavior that lowers the frequency of the

[0068] Next, a description will be given of the effect obtained by using the counter voltage calculation unit 501 according to the embodiment. Fig. 9 is a diagram illustrating the effect of shortening the time required for phase synchronization when the counter voltage calculation unit 501 according to the embodiment is used.

[0069] In FIG. 9, the horizontal axis represents the actual voltage phase difference θ, as in FIG. １ -θ ２9, the vertical axis represents the time required for phase synchronization, i.e., the time required for PLL processing to converge and phase synchronization to be completed. Also, in FIG. 9, the solid line represents the time required for phase synchronization when this method is used, and the dashed line represents the time required for phase synchronization shown as a comparative example. Here, the comparative example is assumed to be a configuration in which the function of the switching unit 820 is removed from the configuration of the counter voltage calculation unit 501 shown in FIG. 8, i.e., a configuration that does not have the function of switching the sign of the frequency correction amount Δω based on the estimated phase difference Δθ. The meaning of the dashed dotted line in FIG. 9 will be described later.

[0070] 9, the overhead line voltage is assumed to be 50 [Hz]. Also, the frequency of the voltage supplied to the auxiliary power supply 107 is assumed to be allowed up to 50±3 [Hz], and Δω ０ = 3 × 2π [rad / s]. ＰＬＬ The frequency correction amount Δω when Δθ=90° is Δω ０ To match ＰＬＬ =Δω ０ / V Ｓ ＊ Set to.

[0071] The actual voltage phase difference θ shown on the horizontal axis in FIG. １ -θ ２ is the overhead line voltage V １ is restored and the switch 606 is turned ON. １ -θ ２ The time when the phase synchronization is completed is determined to be 0.1 [rad] or less.

[0072] In the comparative example, the actual voltage phase difference θ １ -θ ２ As the actual voltage phase difference θ approaches 180°, the time required for phase synchronization increases rapidly. In particular, when the actual voltage phase difference θ is 180°, it takes an infinite amount of time, making phase synchronization impossible. １ -θ ２ Even if the phase is 180°, phase synchronization can be completed in less than 0.4 seconds.

[0073] In the above description, the sign of the frequency correction amount Δω is switched based on the determination result of the sign determination unit 803 in order to shorten the time required for phase synchronization. The sign determination unit 803 switches the sign at ±90°, which means that the threshold for switching the sign of the frequency correction amount Δω is ±90°. However, this threshold does not have to be ±90° and may be set to, for example, ±150°. The reason for this will be explained below with reference to FIG. 9.

[0074] 9, a dashed line is drawn as a comparative example, connecting point A on the dashed line with the origin (0,0). This line is a tangent to point A, and is the line with the smallest slope among the lines connecting any point on the dashed line with the origin (0,0). The actual voltage phase difference θ corresponding to point A １ -θ ２ is approximately 157°. Here, the slope of the line is "time required for phase synchronization (vertical axis)" divided by "actual voltage phase difference (horizontal axis)", and increases rapidly from point A onward. An increase in the slope of the line means that the time required for phase synchronization is getting longer. For this reason, 150°, which corresponds to point B, which is close to point A and located to the left of point A, is set as the threshold for sign switching. Note that the curves shown in FIG. 9 are symmetrical, and the actual voltage phase difference θ １ -θ ２ The negative side is set to -150°.

[0075] Therefore, the switching unit 820 provided in the counter voltage calculation unit 501 compares the absolute value of the estimated phase difference Δθ with a threshold, and switches the frequency correction amount Δω to a positive value if the absolute value of the estimated phase difference Δθ is greater than the threshold and the sign of the estimated phase difference Δθ is positive.The switching unit 820 also compares the absolute value of the estimated phase difference Δθ with a threshold, and switches the frequency correction amount Δω to a negative value if the absolute value of the estimated phase difference Δθ is greater than the threshold and the sign of the estimated phase difference Δθ is negative.

[0076] In the above control, comparing the case where the threshold for switching the sign of the frequency correction amount Δω is ±90° with the case where the threshold for switching the sign of the frequency correction amount Δω is ±150°, the former case allows the use of the functions of an existing controller. Therefore, the former case has the advantage of simplifying the control system configuration compared to the latter case. Furthermore, regarding the slope of the line in Figure 9, the value of "actual voltage phase difference (horizontal axis)" divided by "required phase synchronization time (vertical axis)" (when the vertical and horizontal relationships are reversed) corresponds to the difference between the average frequency during PLL operation and the frequency of the overhead line voltage, i.e., the average frequency correction amount during PLL operation. Therefore, when the latter case is adopted, the effect of shortening the required phase synchronization time while suppressing an increase in the average frequency correction amount during PLL operation is obtained.

[0077] Next, specific operational waveforms will be described with reference to FIGS. 10 to 15 . FIG. 10 is a diagram showing voltage and current waveforms of key parts in a comparative example when the actual voltage phase difference is 180°. FIG. 11 is a diagram showing PLL operational waveforms in a comparative example when the actual voltage phase difference is 180°. FIG. 12 is a diagram showing voltage and current waveforms of key parts in the present system when the actual voltage phase difference is 180°. FIG. 13 is a diagram showing PLL operational waveforms in the present system when the actual voltage phase difference is 180°. FIG. 14 is a diagram showing voltage and current waveforms of key parts in the present system when the actual voltage phase difference is 150°. FIG. 15 is a diagram showing PLL operational waveforms in the present system when the actual voltage phase difference is 150°.

[0078] 10, 12 and 14 show, from top to bottom, (a) overhead line voltage V １ 11, 13 and 15 show, from top to bottom, (a) the switch 606 closing signal, (b) the synchronization determination result, (c) the overhead line voltage V １ , PLL voltage V ２ｐ , (c) counter voltage command value V ２ ＊ , (d) Counter voltage command value V ２ ＊ The waveforms of the frequencies are shown.

[0079] 10 and 11 show the simulation results for the comparative example when the actual voltage phase difference is 180°, FIGS. 12 and 13 show the simulation results for the present method when the actual voltage phase difference is 180°, and FIGS. 14 and 15 show the simulation results for the present method when the actual voltage phase difference is 150°.

[0080] 11, 13, and 15(a), the thick dashed line represents the closing signal of the switch 606, and the thick solid line represents the synchronization determination result. Also, in each of FIGS. 11, 13, and 15(b), the thick dashed line represents the overhead line voltage V １ The thin solid line represents the PLL voltage V ２ｐ In addition, the overhead line voltage V shown in each of (a) of Figs. 10, 12 and 14 represents １ , the overhead line voltage V shown in each of (b) of FIG. 11, FIG. 13 and FIG. 15 １ and PLL voltage V ２ｐ are all secondary-side converted values.

[0081] In the operation of the comparative example when the actual voltage phase difference is 180°, as shown in FIG. 11(b), the overhead line voltage V １ After recovery, the overhead line voltage V １ and PLL voltage Ｖ２ｐ It can be seen that synchronization is not completed even after a further 0.4 [s] has elapsed. The reason for this is that, as described with reference to Fig. 7, when the actual voltage phase difference is 180 [°], the estimated phase difference Δθ is estimated to be substantially zero, so the output of the gain applying unit 605 becomes a small value and the PLL does not function sufficiently.

[0082] On the other hand, in the operation of this method when the actual voltage phase difference is 180 [°], as shown in FIG. 13(b), the overhead line voltage V １ After the power is restored, the overhead line voltage V １ and PLL voltage V ２ｐIt can be seen that the voltage phase is matched with that of the auxiliary power supply 107, and phase synchronization is completed in approximately 0.3 [s]. Once phase synchronization is complete, a closing signal is sent to the switch 103. Looking at the waveform of the power receiving voltage of the auxiliary power supply 107 shown in Figure 12(c), it can be seen that there are differences in the harmonic components originating from the converter 210 and the auxiliary power supply 107 between the waveform before the switch 103 is closed and the waveform after the switch 103 is closed, but it can be seen that voltage is always being supplied. Furthermore, as shown in Figure 13(d), it can be seen that the frequency of the supplied voltage is within the range of 50 ± 3 [Hz], as originally designed.

[0083] 10 to 13, synchronization is achieved by increasing the frequency correction amount Δω, whereas synchronization is achieved by decreasing the frequency correction amount Δω in Fig. 14 and Fig. 15. In other words, it can be seen that by using the technique of this method, correct operation is achieved whether the frequency correction amount Δω is increased or decreased.

[0084] Although the above describes phase synchronization between the converter voltage phase and the overhead line voltage phase when a railway vehicle passes through a dead section, the present invention is not limited to this example. For example, the present method can also be applied to phase synchronization when the overhead line experiences a momentary power outage, and the above-mentioned effects can be achieved.

[0085] As described above, in the railcar power conversion device according to the embodiment, the control device includes a converter control unit that controls the converter to supply regenerative power generated by the traction motor to the second power conversion device via the main transformer during a power-loss period when no power is supplied from the overhead line. 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 a detected value of the overhead line voltage. The voltage phase estimation unit estimates the phase of the AC voltage to be applied to the second power conversion device during the power-loss 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 a phase difference between a first phase that is the phase of the first voltage and a second phase that is the phase of the second voltage. The first voltage is the overhead line voltage detected by the voltage detector after the end of the power-loss 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 power-loss 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, which is an estimate of the phase difference. This railcar power conversion device configured in this manner can solve the problem of the estimated phase difference being underestimated when the actual voltage phase difference is large, resulting in a long time required for phase synchronization. This makes it possible to suppress an increase in the time required for phase synchronization even if the overhead line voltage frequency deviates from the rated value. The unpowered period referred to here may include the period during which the railcar passes through a dead section and the period before and after that period, or may be the period from when the overhead line experiences a momentary power outage until the power is restored.

[0086] In the above configuration, the converter control unit increases the frequency of the second voltage when the sign of the estimated phase difference is positive, and decreases the frequency of the second voltage when the sign of the estimated value of the estimated phase difference is negative. The switching unit compares the absolute value of the estimated phase difference with a predetermined threshold, and switches the frequency correction amount to a positive value when the absolute value of the estimated phase difference is greater than the threshold and the sign of the estimated phase difference is positive. The switching unit compares the absolute value of the estimated phase difference with a predetermined threshold, and switches the frequency correction amount to a negative value when the absolute value of the estimated phase difference is greater than the threshold and the sign of the estimated phase difference is negative. This type of control is compatible with existing control systems and can be easily incorporated into existing control systems.

[0087] In the above control, the threshold value for comparison with the absolute value of the estimated phase difference can be set to, for example, 90 degrees or 150 degrees. Setting the threshold value to 90 degrees simplifies the configuration of the control system. Setting the threshold value to 150 degrees reduces the time required for phase synchronization while suppressing an increase in the average frequency correction amount during PLL operation.

[0088] Finally, a hardware configuration for realizing the functions of the converter control unit 242 described above will be described with reference to Fig. 16 and Fig. 17. Fig. 16 is a block diagram showing an example of a hardware configuration for realizing the functions of the converter control unit 242 in the embodiment. Fig. 17 is a block diagram showing another example of a hardware configuration for realizing the functions of the converter control unit 242 in the embodiment.

[0089] When realizing some or all of the functions of the converter control unit 242 in the embodiment, the configuration can include a processor 300 that performs calculations, a memory 302 that stores programs read by the processor 300, and an interface 304 that inputs and outputs signals, as shown in Figure 16.

[0090] The processor 300 is a computing means. The processor 300 may be a computing means called a microprocessor, a microcomputer, a central processing unit (CPU), or a digital signal processor (DSP). Examples of the memory 302 include non-volatile or volatile semiconductor memory such as random access memory (RAM), read-only memory (ROM), flash memory, erasable programmable read-only memory (EPROM), and electrically programmable read-only memory (EEPROM), as well as magnetic disks, flexible disks, optical disks, compact disks, minidisks, and digital versatile disks (DVDs). The memory 302 may be a combination of multiple storage devices, such as a RAM and an EEPROM.

[0091] A program for executing the functions of converter control unit 242 in the embodiment is stored in memory 302. Processor 300 exchanges necessary information via interface 304, executes the program stored in memory 302, and refers to the table stored in memory 302, thereby performing the above-mentioned processing. The results of calculations by processor 300 can be stored in memory 302.

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

[0093] It is also possible that some of the processing in the converter control unit 242 is performed by the processing circuit 303 , and the processing that is not performed by the processing circuit 303 is performed by the processor 300 and the memory 302 .

[0094] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, and parts of the configurations may be omitted or modified without departing from the spirit of the invention.

[0095] 100 overhead line, 101 power receiving unit, 102 ACPT, 103 switch, 104 main transformer, 105 main converter, 106 traction motor, 107 auxiliary power supply unit, 141 primary winding, 142 secondary winding, 143 tertiary winding, 210 converter, 211, 231 primary side terminal, 212, 232 secondary side terminal, 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 opposing voltage calculation unit, 502 voltage phase estimation unit, 503 current control unit, 504 voltage command calculation unit, 505 converter drive signal generation unit, 601, 605 Gain applying unit, 602 cosine calculation unit, 603, 610, 801, 804 multiplication unit, 604, 802 LPF, 606, 611, 805 switch, 607 addition unit, 608 integrating unit, 609 sine calculation unit, 612 BPF, 803 sign determination unit, 810 phase difference estimation unit, 820 switching unit.

Claims

1. a first power conversion device connected to a secondary winding of the main transformer and connected to a propulsion motor for driving the railway vehicle, the first power conversion device having a converter that converts an AC voltage applied via the main transformer into a DC voltage and mounted on a railway vehicle having a main transformer, a primary winding of the main transformer connected to an overhead line via a power receiving unit, a switch that electrically connects or disconnects the main transformer and the overhead line, and a voltage detector that is provided between the overhead line and the switch and detects an overhead line voltage applied from the overhead line, the first power conversion device being connected to a secondary winding of the main transformer and connected to a propulsion motor for driving the railway vehicle, a second power conversion device connected to a tertiary winding of the main transformer and supplying power to auxiliary machinery mounted on the railway vehicle, and a control device that controls operation of the switch and the first and second power conversion devices, the control device includes a converter control unit that controls the converter to supply regenerative power generated by the traction motor to the second power conversion device via the main transformer during a power-loss period when power is not supplied from the overhead line, The converter control unit a reference voltage calculation unit that calculates a reference voltage serving as a reference for current control of the converter based on the detected value of the overhead line voltage; a voltage phase estimator that estimates a phase of an AC voltage to be applied to the second power conversion device during the non-power supply period based on the reference voltage; Equipped with The reference voltage calculation unit is a phase difference estimation unit that estimates a phase difference between a first phase, which is a phase of a first voltage when an overhead line voltage detected by the voltage detector after the end of the non-power-feeding period is defined as a first voltage, and a second phase, which is a phase of a second voltage when 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-feeding period is defined as a second voltage; a switching unit that switches a sign of a frequency correction amount for correcting a frequency of the second voltage based on an estimated phase difference that is an estimate of the phase difference; A power conversion device for a railway vehicle comprising:

2. The non-powered period includes the period during which the railcar passes through the dead section and the period before and after the period.

2. The power conversion device for railcars according to claim 1 .

3. The non-power supply period is the period from when the overhead line experiences a momentary power outage to when the power is restored.

2. The power conversion device for railcars according to claim 1 .

4. The converter control unit When the sign of the estimated phase difference is positive, increasing 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.

4. The power converter for a railway vehicle according to claim 1, wherein the power converter is a power converter for a railway vehicle.

5. The switching unit compares an absolute value of the estimated phase difference with a predetermined threshold, and switches the frequency correction amount to a positive value when the absolute value is greater than the threshold and the sign of the estimated phase difference is positive.

2. The power conversion device for railcars according to claim 1 .

6. The switching unit compares an absolute value of the estimated phase difference with a predetermined threshold, and switches the frequency correction amount to a negative value when the absolute value is greater than the threshold and the sign of the estimated phase difference is negative.

2. The power conversion device for railcars according to claim 1 .

7. The threshold is 90 degrees.

7. The power converter for railway vehicles according to claim 5 or 6.

8. The threshold is 150 degrees.

7. The power converter for railway vehicles according to claim 5 or 6.