RAIL VEHICLE POWER CONVERTER DEVICE

Abstract

In a railway vehicle power converter device, a converter control unit (242) of a control device (240) comprises a counter voltage calculation unit (501) that calculates a counter voltage serving as a reference for current control of a converter (210) based on a detection value of a car voltage, and a voltage phase estimation unit (502) that estimates a phase of an AC voltage applied to an auxiliary power supply device (107) during a power-free period based on the counter voltage.The counter voltage calculation unit (501) comprises: a phase difference estimation unit (810) that estimates a phase difference between a first phase, which is a phase of a first voltage, and a second phase, which is a phase of a second voltage, wherein the first voltage is a carriage voltage detected by an ACPT (102) after the power-free period ends, wherein the second voltage is an AC voltage estimated by the voltage phase estimation unit (502) based on a carriage voltage detected by the ACPT (102) before the power-free period begins; and a switching unit (820) that switches a sign of a frequency correction quantity for correcting a frequency of the second voltage based on an estimated phase difference, which is an estimated value of the phase difference.

Description

Area

[0001] The present disclosure relates to a railway vehicle power conversion device for railway vehicles that travel by receiving alternating current (AC) power supplied from an AC trolley line. background

[0002] An AC-electrified railway has limited feeder sections, i.e., areas where a single electrical substation feeds or supplies power. The AC power has different voltage phases for different electrical substations. For this reason, the railway has a section within which no power is fed, and such a section is provided at a boundary between the feeder sections. This section is called a "dead section." As such, a rolling stock that is moving and that receives AC power fed from an AC car line will not receive AC power from the AC car line while traversing the dead section.During such a period, regenerative power from a traction motor for propelling the rail vehicle could be fed to an auxiliary device installed in the rail vehicle, thereby continuing the power supply to the auxiliary device as during normal running. This mode of operation is called "pump back." It should be noted that the term "auxiliary device" refers to a device other than the traction motor among the devices installed in the rail vehicle that are supplied with electrical power. Power supply to an auxiliary device is enabled by a power conversion device called an auxiliary power supply device.

[0003] When power supply from the car line resumes after the rail vehicle passes through the dead section, a circuit breaker of a power receiving unit is closed to switch to normal car power supply. When switching to car power supply, the circuit breaker must be closed under a condition that the phase of the voltage to be applied to the main transformer before switching matches the phase of the car voltage to be applied after switching, to prevent excessive current from flowing in a case where the car line is an AC car line. For a circuit configuration in which the auxiliary power supply device is connected to the tertiary winding of the main transformer, phasing is performed while the AC voltage is continuously applied to the main transformer.

[0004] With such a technological background, Patent Literature 1 presented below discloses a technology for achieving phase synchronization between a converter voltage and a carriage voltage by directly determining a carriage voltage phase, which is the phase of the carriage voltage, and by increasing the frequency so that the converter voltage phase can catch up with this carriage voltage phase. Citation listPatent literature

[0005] Patent Literature 1: Japanese Patent No. 6510060 SummaryTechnical problem

[0006] Unfortunately, the foregoing Patent Literature 1 does not describe a specific method for directly determining the car voltage phase. Furthermore, a method for directly calculating the car voltage phase as described in Patent Literature 1 presents a problem in that phase detection is difficult when the car voltage frequency deviates from a nominal value and when a longer time is required for phase synchronization, which allows the converter voltage phase to catch up with the car voltage phase.

[0007] The present disclosure has been made in view of the foregoing, and it is an object of the present disclosure to provide a railway vehicle power converter device capable of reducing an increase in the time required for phase synchronization even when the car voltage frequency deviates from its rated value. Solution to the problem

[0008] To solve the problem and achieve the above-described object, a railway vehicle power conversion device according to the present disclosure is installed in a railway vehicle and includes a main transformer, a switchgear, and a voltage detector. The main transformer has a primary winding connected to a car line via a power receiving unit. The switchgear electrically disconnects or connects the main transformer to the car line. The voltage detector is arranged between the car line and the switchgear to detect a car voltage applied from the car 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 converter device is connected to a secondary winding of the main transformer and is connected to a drive motor for driving the rail vehicle. The first power converter device comprises a converter for converting an AC voltage applied via the main transformer into a DC voltage. The second power converter device is connected to a tertiary winding of the main transformer for supplying electrical power to an auxiliary device installed in the rail vehicle. The control device controls operations of the switchgear and the first and second power converter devices.The control device includes a converter control unit for performing control by controlling the converter to supply regenerative power generated by the drive motor to the second power converter device via the main transformer during a power-off period, wherein the power-off period is a period during which no electric power is supplied from the car 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 based on a detection value of the car voltage, the reference voltage serving as a reference for current control of the converter. The voltage phase estimation unit estimates, based on the reference voltage, a phase of an AC voltage applied to the second power converter device during the power-off period.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 and a second phase, the first phase being a phase of a first voltage, and the second phase being a phase of a second voltage. The first voltage is a carriage voltage detected by the voltage detector after the power-free period ends. The second voltage is an AC voltage estimated by the voltage phase estimation unit based on a carriage voltage detected by the voltage detector before the power-free period begins. The switching unit switches a sign of a frequency correction quantity for correcting a frequency of the second voltage based on an estimated phase difference, the estimated phase difference being an estimated value of the phase difference. Advantageous effects of the invention

[0009] The railway vehicle power converter device according to the present disclosure enables the advantage of reducing the increase in time required for phase synchronization even when the car voltage frequency deviates from its rated value. Short description of the drawings Fig. 1 is a diagram illustrating an exemplary configuration of an electrical system of a rail vehicle system including a rail vehicle power conversion device according to an embodiment. Fig. Figure 2 shows a diagram showing an exemplary configuration of the Fig. 1 illustrated main transducer devices. Fig. 3 is a diagram for describing a power flow during normal operation in the railway vehicle power conversion device according to the embodiment. Fig. 4 illustrates a diagram for describing an energy flow during a power-free period in the railway vehicle power conversion device according to the embodiment. Fig. 5 illustrates a flowchart for describing an operation during a pump-back operation in the embodiment. Fig. 6 is a block diagram illustrating an exemplary configuration of a converter control unit according to the embodiment. Fig. Figure 7 is a diagram for describing a conventional method using a phase-locked loop (PLL). Fig. 8 is a block diagram illustrating an exemplary configuration of a counter voltage calculation unit according to the embodiment. Fig. 9 is a diagram for describing an effectiveness of reducing the time required for phase synchronization provided by use of the counter voltage calculation unit according to the embodiment. Fig. 10 is a diagram illustrating voltage waveforms and current waveforms of a main part in a comparative example when the actual voltage phase difference is 180[°]. Fig. 11 is a diagram illustrating PLL operation waveforms in the comparative example when the actual voltage phase difference is 180[°]. Fig. 12 is a diagram illustrating voltage waveforms and current waveforms of a main part provided by a method described herein when the actual voltage phase difference is 180[°]. Fig. Figure 13 is a diagram illustrating PLL operating waveforms provided by the method described herein when the actual voltage phase difference is 180[°]. Fig. 14 is a diagram illustrating voltage waveforms and current waveforms of the main part provided by the method described here when the actual voltage phase difference is 150[°]. Fig. Figure 15 is a diagram illustrating the PLL operating waveforms provided by the method described herein when the actual voltage phase difference is 150[°]. Fig. 16 is a block diagram illustrating an example of a hardware configuration for implementing a functionality of the converter control unit in the embodiment. Fig. 17 is a block diagram illustrating another example of a hardware configuration for implementing a functionality of the converter control unit in the embodiment. Description of the embodiment

[0010] A railway vehicle power converter device according to an embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be noted that no distinction is made here between a physical connection and an electrical connection, both of which will be referred to simply as "connection" in the following description. This means that the term "connection" covers both a case where components are directly connected to each other and a case where components are indirectly connected to each other with another component arranged therebetween. Embodiment.

[0011] Fig. 1 is a diagram illustrating an exemplary configuration of an electrical system of a rail vehicle system including a rail vehicle power conversion device according to an embodiment. The rail vehicle system according to the embodiment includes a power receiving unit 101, an alternating current potential transformer (ACPT) 102, a switchgear 103, a main transformer 104, main conversion devices 105, drive motors 106, and auxiliary power supply devices 107. The alternating current potential transformer (ACPT) 102 serves as a voltage detector. It should be noted that, although Fig. 1 illustrates the four main converter devices 105 and the four drive motors 106 by way of example, different numbers of the main converter devices 105 and the drive motors 106 could be provided. Although Fig. 1 illustrates that the drive motors 106 are connected in a one-to-one correspondence to the main converter devices 105, the multiple drive motors 106 could also be connected to the single main converter device 105. Furthermore, although Fig. 1 illustrates that the single auxiliary power supply device 107 is connected to the main transformer 104, the plurality of auxiliary power supply devices 107 are connected to the main transformer 104. Furthermore, the main converter devices 105 and the auxiliary power supply device 107 in Fig. 1 the railway vehicle power converter device according to the embodiment.

[0012] The power input unit 101 is a device that enables the rail vehicle to input or receive AC power from a trolley line 100. Examples of the power input unit 101 include a pantograph and a contact shoe. The rail vehicle is described here as being powered by a pantograph mounted on an upper portion of the rail vehicle, but it could be powered by a third rail laid along the track.

[0013] Switchgear 103 is a device that electrically connects and breaks the connection between main transformer 104 and car line 100. An example of switchgear 103 is a circuit breaker. A vacuum circuit breaker (VCB) is often used in a rail vehicle. It should be noted that switchgear 103 does not necessarily have to be a circuit breaker, but it could be any device capable of connecting and breaking the connection between main transformer 104 and car line 100, i.e., disconnecting or connecting main transformer 104 to car line 100.

[0014] The ACPT 102 is a device for measuring a voltage received by the power receiving unit 101. The ACPT 102, provided between the car line 100 and the switchgear 103, detects a car voltage applied by the car line 100.

[0015] The main transformer 104 includes a primary winding 141, secondary windings 142, and a tertiary winding 143. The primary winding 141 is connected to the trolley line 100 via the power input unit 101 and the switchgear 103. Furthermore, each of the secondary windings 142 is connected to a corresponding one of the main converter devices 105, and each of the tertiary windings 143 is connected to a corresponding one of the auxiliary power supply devices 107. The trolley voltage is applied to the primary winding 141. Voltages generated in the secondary winding 142 and the tertiary winding 143 are each determined by the ratio of the number of turns relative to the primary winding 141.Typically, the same number of secondary windings 142 as the main converter devices 105 and the same number of tertiary windings 143 as the auxiliary power supply devices 107 are installed such that each winding is connected to a corresponding device; however, a single winding could be connected to multiple devices via choke coils. Note that the voltage applied to the primary winding 141 is the reference voltage used as a reference for current control of the converter 210. This reference voltage is referred to herein as the "countervoltage." Furthermore, this countervoltage is determined here by calculation.

[0016] The main converter device 105 includes the converter 210 and an inverter 230. The converter 210, connected to the secondary winding 142 of the main transformer 104, converts an AC voltage applied via the main transformer 104 into a direct current (DC) voltage. The inverter 230, connected to the drive motor 106, converts the DC voltage applied by the converter 210 into a drive voltage for the drive motor 106 and applies the drive voltage to the drive motor 106. It should be noted that the main converter device 105 could also be referred to as a "first power converter device."

[0017] The drive motor 106 is a motor for driving a rail vehicle. The rail vehicle travels with the drive force generated by the rotation of the drive motor 106. Furthermore, the rail vehicle accelerates or decelerates using a torque generated by the drive motor 106.

[0018] The auxiliary power supply device 107, connected to the tertiary winding 143 of the main transformer 104, supplies power to the auxiliary devices described above. Examples of the auxiliary devices include an on-board lighting device, a door opening and closing device, an air conditioning device, a security device, a compressor, a battery, and a control power supply. It should be noted that the auxiliary power supply device 107 may also be referred to herein as a "second power conversion device."

[0019] Fig. Figure 2 is a diagram illustrating an exemplary configuration of the main transducer devices 105 shown in Fig. 1. The main converter device 105 includes the converter 210, smoothing capacitors 220, the inverter 230, and a control device 240. The control device 240 also includes a converter control unit 242 and an inverter control unit 244.

[0020] The converter 210 includes primary terminals 211 and secondary terminals 212. The converter 210 is capable of converting a single-phase AC voltage applied to the primary terminals 211 into a DC voltage applied to the secondary terminals 212, and vice versa. This operation is controlled by the converter control unit 242. The converter 210 adjusts the voltage at the primary terminals 211, thereby controlling the power for the inverter 230 side. Furthermore, a current sensor 213 is arranged on the side of one of the primary terminals 211. The current sensor 213 detects a current flowing on the primary side of the converter 210. It should be noted that Fig. 2 illustrates, by way of example, a three-stage converter comprising three secondary terminals 212 and capable of outputting three types of electrical potentials to the secondary side, but the converter 210 is not limited to this example. The number of secondary terminals 212 could be two, four, or more. A converter comprising two secondary terminals 212 is called a two-stage converter.

[0021] The inverter 230 includes primary terminals 231 and secondary terminals 232. The inverter 230 is capable of converting a DC voltage applied to the primary terminals 231 into an AC voltage applied to the secondary terminals 232, and vice versa. This operation is controlled by the inverter control unit 244. The inverter 230 adjusts the voltage at the secondary terminals 232, thereby controlling an output torque of the drive motor 106. In a case where the drive motor 106 is a three-phase AC motor, the voltage output to the secondary terminals 232 is a three-phase AC voltage. It should be noted that Fig. 2 illustrates, by way of example, a two-level inverter including two primary terminals 231 and capable of outputting two types of electrical potentials to the primary side, but the inverter 230 is not limited to this example. The number of primary terminals 231 could be three or more. An inverter including three primary terminals 231 is called a three-level inverter.

[0022] The smoothing capacitors 220, connected between the secondary terminals 212 of the converter 210 and the primary terminals 231 of the inverter 230, have functionality to reduce or eliminate a variation in the DC voltage. In a case where the converter 210 and the inverter 230 both have a two-stage configuration, the number of smoothing capacitors 220 could be one. Furthermore, voltage sensors 221 are arranged in parallel with the smoothing capacitors 220. The voltage sensors 221 each detect a capacitor voltage, which is the voltage across both ends of a corresponding one of the smoothing capacitors 220.

[0023] Fig. 3 is a diagram for describing an energy flow in the railway vehicle power converter device according to the embodiment during normal operation. In addition, Fig. 4 is a diagram for describing a power flow in the railway vehicle power conversion device according to the embodiment during a power-free period. Note that the term "during normal operation" refers to a period during which power is properly supplied from the car line 100 to the main transformer 104. Furthermore, the term "during a power-free period" indicates a concept that includes not only the period during which the railway vehicle actually passes through a dead section, but also the preceding and subsequent periods during which the switchgear is in an open state. That is, the term "during a power-free period" refers to a period during which the main transformer 104 is electrically disconnected from the car line 100 and thus does not receive any electrical power from the car line 100.

[0024] During normal operation, the electrical power required to drive the rail vehicle is supplied to the main converter device 105 and the auxiliary power supply device 107 via the power input unit 101, the switchgear 103, and the main transformer 104. The main converter device 105 converts the supplied power into drive power for the drive motor 106, thus driving the drive motor 106. The auxiliary power supply device 107 converts the supplied power into drive power for operating the auxiliary device.

[0025] During the power-off period, no electrical power can be supplied from the car line 100. Thus, the converter control unit 242 of the control device 240 performs a pump-back operation, which allows kinetic energy of the drive motor 106 to generate regenerative power, so that the regenerative power is supplied to the auxiliary power supply device 107 via the main converter device 105 and the main transformer 104. The following description regarding the main converter device 105 is to be interpreted as indicating the main converter device 105 that performs the pump-back operation. It is assumed that only one of the main converter devices 105 for each main transformer 104 performs the pump-back operation. The pump-back operation of each of the main converter devices 105 can prevent instability of the regenerative power supplied to the main transformer 104.The individual main converter devices 105 that performs the pump-back operation can be predetermined or specified by a train information management device that manages train information. The power-off period resulting from passing through a dead section is a short period of time during which the auxiliary power supply device 107 consumes a sufficiently smaller amount of power than the kinetic energy of the traction motor 106 and the rail car. Thus, when an individual main converter device 105 performs the pump-back operation, it is possible to prevent a situation such as rapid deceleration of the train.

[0026] Fig. Fig. 5 is a time chart for describing an operation during a pump-back operation in the embodiment. The horizontal axis of the Fig. 5 represents time. It also illustrates Fig. 5 shows, along the vertical axis direction, in order from top to bottom, a detected waveform of the ACPT 102, a dead section crossing notification signal, a torque pattern, a pump-back status signal, a status signal of the switchgear 103, and a voltage waveform for use in converter control.

[0027] A dead section crossing notification signal is issued before the rail vehicle enters a dead section. In concrete terms, this means that in the example of the Fig. 5, the dead section crossing notification signal is output at time t1, and output of the dead section crossing notification signal ends at time t10. A regeneration operation starts at time t2, and the pump-back operation starts at time t3. The switchgear 103 is opened at time t4. The open state continues until time t11. The time period from time t5 to time t6 is the time period during which the rail vehicle actually crosses the dead section. During the time period from time t7 to time t8, control is performed to adjust the output voltage waveform of the converter 210 to the detected waveform of the ACPT 102. The pump-back operation ends at time t9, and the regeneration operation switches to a power running operation at time t12.

[0028] Next, a behavior of the main transformer 104 and the main converter device 105 is described below with reference to the timing chart of the Fig. 5. When electric power is supplied from the trolley line 100, the converter 210 is first operated to make the capacitor voltages constant. The main transformer 104 outputs a single-phase AC voltage to the primary terminals 211 of the converter 210, thus enabling the converter 210 to receive a required power. The converter 210 outputs a DC voltage to the secondary terminals 212, thus enabling the smoothing capacitors 220 to have a voltage following the voltage specified by a command value. Meanwhile, the inverter 230 outputs a voltage to the secondary terminals 232, thus enabling the drive motor 106 to output a torque specified by a command value.

[0029] When a dead-section crossing notification signal is issued and the inverter 230 receives this signal at time t1, the inverter 230 reduces a power running torque and then stops supplying current to the traction motor 106. This causes the traction motor 106 to rotate in a free-running mode, so that the rail vehicle enters a free-running state. When the operation switches to the pump-back operation at time t3, the inverter 230 is operated to enable the traction motor 106 to supply regenerative power required to maintain the capacitor voltages. When the pump-back operation begins and subsequently, the regenerative power from the main converter device 105 nearly matches the power consumption of the auxiliary device connected to the auxiliary power supply device 107, a current flowing to the switchgear 103 approaches zero.This makes it possible to open switchgear 103 at time t4.

[0030] The car voltage cannot be measured during the period from time t5 to time t6, where the rail car actually passes through a dead section. For this reason, control in which the car voltage is not checked begins from time t4, at which the status signal of the switchgear 103 assumes an OFF state, that is, from a time t4 before time t5. More specifically, this means that the converter 210 outputs a voltage having a certain amplitude and frequency to the primary terminals 211 without checking the car voltage. During this operation, the capacitor voltages are not controllable because the power supplied by the converter 210 depends on the load of the auxiliary power supply device 107. Therefore, the capacitor voltages are then controlled by the inverter control unit 244.The inverter control unit 244 controls the inverter 230 such that the torque command for the drive motor 106 provides the amount of regenerative torque needed to obtain the power required to maintain the capacitor voltages. Control, in which the car voltage is not checked, continues until time t7, which occurs after the rail vehicle traverses the dead zone.

[0031] After time t6, when the rail vehicle passes through the dead section, the ACPT 102 resumes measuring the car voltage. Unfortunately, closing the switchgear 103 at this time may cause excessive inrush current to flow into the main transformer 104 because the car voltage and the voltage generated by the converter 210 are out of phase with each other. To prevent this excessive current, the converter 210 performs control in which the generated voltage gradually adapts to the detected waveform of the ACPT 102. More specifically, this means that as power continues to be fed into the auxiliary power supply device 107, the converter 210 performs control in which the frequency of the generated voltage is slowly changed to synchronize the phase of the generated voltage with the phase of the car voltage. Fig. Figure 5 illustrates an example in which the phase of the generated voltage is synchronized with the phase of the car voltage at time t8, and the pump-back operation ends at the subsequent time t9, after which the switchgear 103 is closed at time t11. From time t11 onward, power injection from the car line 100 resumes, so the converter 210 begins to perform DC voltage control again, and the inverter 230 begins to perform motor torque control again.

[0032] The car voltage sensed by ACPT 102 after the power-off period ends could be referred to herein as the "first voltage" and the phase of this first voltage as the "first phase." Furthermore, the AC voltage that converter control unit 242 generates during the power-off period based on the car voltage sensed by ACPT 102 before the power-off period begins could be referred to herein as the "second voltage" and the phase of this second voltage as the "second phase."

[0033] Fig. 6 is a block diagram illustrating an exemplary configuration of the converter control unit 242 according to the embodiment. The converter control unit 242 of the embodiment includes, as shown in Fig. 6 illustrates a counter voltage calculation unit 501, a voltage phase estimation unit 502, a current control unit 503, a voltage command calculation unit 504, and a converter control signal generation unit 505.

[0034] The reverse voltage calculation unit 501 calculates a reverse voltage command value V2*, which is a command value for a reverse voltage V2, based on a car voltage V1 received by the ACPT 102. A relationship V1=V2* applies when the switchgear 103 is closed, whereas these voltage values are fundamentally different from each other when the switchgear 103 is open.

[0035] The voltage phase estimation unit 502 estimates an estimated voltage phase θ s , which represents an estimated value of the voltage phase of the carriage voltage V1 based on the counter voltage command value V2*. The counter voltage command value V2* has a single-phase sinusoidal waveform. The voltage phase estimation unit 502 calculates the estimated voltage phase θ sbased on the reverse voltage command value V2*, which satisfies the relationship V1=V2* during normal operation. More specifically, when the reverse voltage command value V2* is taken as a sinusoidal value, the voltage phase estimation unit 502 operates to detect the instantaneous voltage of the reverse voltage command value V2* switches from a negative value to a positive value and adjusts the phase to 0° at that time. For this reason, the reverse voltage command value V2* must be a sinusoidal value with only a small ripple.

[0036] During normal operation, the current control unit 503 performs an output voltage correction to cause a capacitor voltage V dc a capacitor voltage command value V dc*, which is a command value for the capacitor voltage. During pump-back operation, the current control unit 503 performs an output voltage correction to cause the counter voltage V2 to follow the counter voltage command value V2*. More specifically, this means that during normal operation, the current control unit 503 maintains a current amplitude required for the capacitor voltage V dc the capacitor voltage command value V dc * follows, based on a load power P m expected in the inverter 230 and on the detection value of the capacitor voltage V dc which is detected by the voltage sensors 221. The current control unit 503 then calculates a voltage drop V tr in the main transformer 104 based on the calculated current amplitude and the estimated voltage phase θ s, which is output from the voltage phase estimation unit 502. Alternatively, the current sensor 213 detects a current I during a pump-back operation. S flowing on the primary side of the converter 210, and the current control unit 503 calculates the voltage drop V tr in the main transformer 104 based on the detected value of the current I S .

[0037] The voltage command calculation unit 504 calculates a primary side voltage command V ac * based on the counter voltage command value V2* and the voltage drop V tr in the main transformer 104. More specifically, this means that the voltage command calculation unit 504 calculates the voltage command V ac * calculated by taking the voltage drop V tr is subtracted from the counter voltage command value V2*.

[0038] The converter control signal generation unit 505 generates a switching command S c based on the voltage command Vac *, the estimated stress phase θ s and the detection value of the capacitor voltage V dc and outputs the generated switching command S c to the converter 210. Although not illustrated, the converter 210 comprises several switching elements connected together in the form of a bridge circuit. The switching command S c is a command to switch on or off each of the multiple switching elements at a desired time. The switching command S c can be generated using, for example, a pulse width modulation (PWM) method, which is a known control method. In accordance with the switching command S c a voltage corresponding to the voltage command V ac * output to the primary terminals 211 of the converter 210.

[0039] A problem of a conventional method will be described next. As described above, the counter voltage calculation unit 501 calculates the counter voltage command value V2*, which is the command value for the counter voltage V2, based on the car voltage V1 input by the ACPT 102. The counter voltage command value V2* is typically calculated using a phase-locked loop (PLL). A PLL, also called a phase-locked loop, is a technique for calculating a desired phase in feedback control that sets an input signal and an output signal in phase with each other. The railway power converter device of the present disclosure uses a PLL in a similar manner, but the conventional technique presents a problem, which is described below. Fig. Figure 7 is a diagram for describing the conventional technique using a PLL.

[0040] In Fig. 7, the sine wave indicated by the solid line is the curve used in phase estimation. The horizontal axis represents the actual voltage phase difference θ1-θ2, which is a real voltage phase difference, and the vertical axis represents the estimated phase difference Δθ in the conventional technique. The dashed line is a straight line representing a ratio of the estimated phase difference Δθ that matches the actual voltage phase difference θ1-θ2. In phase estimation control, a difference between the actual and the dashed line appears as the error component in the estimated phase difference Δθ. In this regard, the conventional technique uses the value of sine (θ1-θ2) to calculate the estimated phase difference Δθ using a ratio of (θ1-θ2)≈sin(θ1-θ2) when the actual voltage phase difference θ1-θ2 is small.However, the difference increases, as in . Fig. As illustrated in Figure 7, the difference between θ1-θ2 and sin(θ1-θ2) starts near 30[°] in absolute value of the actual voltage phase difference θ1-θ2, and further increases rapidly in the range of more than 90[°] in absolute value. This poses a problem of the estimated phase difference Δθ being smaller than the actual one, and requiring time for phase synchronization when the actual voltage phase difference θ1-θ2 is large. In particular, when the absolute value of the actual voltage phase difference θ1-θ2 is 180[°], sin(θ1-θ2)=0. As a result, the PLL does not work well, raising a critical problem of voltage phase non-correction.

[0041] A control method that enables a solution to the previous problem will be described below. Fig. 8 is a block diagram illustrating an exemplary configuration of the counter voltage calculation unit 501 according to the embodiment. The counter voltage calculation unit 501 according to the embodiment includes, as shown in Fig. 8 illustrates gain application 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 addition unit 607, an integration unit 608, a sine calculation unit 609, a band-pass filter (BPF) 612 and a sign determination unit 803. It should be noted that in Fig. 8, the cosine calculation unit 602, the multiplication unit 603, and the LPF 604 form a phase difference estimation unit 810. The multiplication units 801 and 804, the LPF 802, the sign determination unit 803, and the switch 805 form a switching unit 820.

[0042] An operation of the counter voltage calculation unit 501, which is Fig. 8 will be described next. First, the gain application unit 601 applies a gain N to the carriage voltage V1, which is received by the ACPT 102. As a result, the voltage value of a voltage V b , which is an output from the gain application unit 601, is converted into a voltage value equivalent to the voltage of the secondary winding 142 of the main transformer 104. Note that the gain N is the quotient obtained by dividing the number of turns of the primary winding 141 by the number of turns of the secondary winding 142 of the main transformer 104.

[0043] Next, the cosine calculation unit 602 calculates a cosine value cosθ using a voltage phase θ generated in the counter-voltage calculation unit 501. This calculation process is equivalent to a process of generating a voltage waveform advanced by 90°, where the voltage has peak values of ±1. In this regard, the voltage phase θ at this moment is expressed by a formula (1) below using an angular frequency ω0 and a phase θ2 at time 0 [s] (seconds). In addition, the voltage V b output from the gain application unit 601 is expressed by a formula (2) below using the frequency ω0 and a phase θ1 at time 0 [s]. Formula 1: θ[rad]=ω0t+θ2 Formula 2: Vb=Vs*⋅sin(ω0t+θ1)

[0044] In formula (2) above, V s* a rated voltage amplitude representing the rated value of the carriage voltage V1. The multiplication unit 603 multiplies the output of the gain application unit 601 by an output of the cosine calculation unit 602. The multiplication result is expressed by a formula (3) below. Formula 3: Vb⋅cos(ω0t+θ2)=Vs*⋅(sin(θ1−θ2)+sin(2ω0t+θ1+θ2)) / 2

[0045] The right side of formula (3) above represents the sum of a voltage component that varies with time and a voltage component that pulsates at an angular frequency twice the angular frequency of the voltage. Thus, the LPF 604 is designed to retain only the first component and remove the second component. The LPF 604 has a set transfer function, for example, formula (4) below. Using the LPF 604 set in this way allows for sufficient removal of the component with an angular frequency of 2ω0. Formula 4: (0.2ω0)2s2+(1.4⋅0.2ω0)⋅s+(0.2ω0)2

[0046] The LPF 604 provides an output of V s *{sin(θ1-θ2)} / 2. For the conventional method, the output of the LPF 604, which is considered to be almost equal to “V S*(θ1-θ2) / 2“ is processed under the assumption that the difference between θ1 and θ2 is sufficiently small, as described above.

[0047] The gain application unit 605 provides a gain K PLL for the output of the LPF 604. This operation converts the output of the gain application unit 605 into a frequency correction quantity Δω. The frequency correction quantity Δω is input to the switch 606 through the switch 805. An operation of the switch 805 will be described later.

[0048] Next, a behavior using the frequency correction quantity Δω will be described. Using the frequency correction quantity Δω allows increasing and decreasing the frequency of the voltage V b . For example, if the voltage phase of the car voltage V1 corresponds to the estimated voltage phase θ swhich is the estimated value of the voltage phase of the car voltage V1, the increase in the frequency of the voltage V b in a behavior that corresponds to the estimated stress phase θ s allows to catch up with the voltage phase of the car voltage V1. In contrast, if the voltage phase of the car voltage V1 is equal to the estimated voltage phase θ s lags, the reduction of the frequency of the voltage V b in a behavior that allows the voltage phase of the car voltage V1 to reach the estimated voltage phase θ s to obtain.

[0049] Switch 606 is normally closed (ON) during normal operation, is turned off during pumpback operation, and is returned to an ON state when car power injection resumes following the rail vehicle's traversal of the dead zone. As such, switch 606 receives the frequency correction quantity Δω during normal operation and receives 0 during pumpback operation. As a result, the control system enables the PLL when switch 606 is in an ON state and disables the PLL when switch 606 is in an OFF state, so that a voltage with a fixed frequency is output to the primary terminals 211.

[0050] The adding unit 607 adds the frequency correction quantity Δω or 0 to the nominal angular frequency ω0 2π times the nominal frequency of the trolley line 100 and inputs the sum to the integrating unit 608 located downstream of it. This means that the adding unit 607 converts the frequency of the output of the switch 606 into the frequency of the voltage to be output to the primary terminals 211 of the converter 210. Frequencies of 16.7, 25, 50, and 60 [Hz] and the like are typically used as the nominal frequency of the AC-electrified trolley line.

[0051] The integrating unit 608 integrates the output of the adding unit 607, and its integrated value is output as the aforementioned voltage phase θ to the cosine calculating unit 602 and the sine calculating unit 609. Since the switch 606 is controlled to an ON state during normal operation, the car voltage phase is stored in the integrating unit 608. Alternatively, the phase behaves in such a way that it changes at the rated angular frequency based on the car voltage phase stored in the integrating unit 608 during the power-off period and approaches the car voltage phase when the PLL restarts its operation after the rail car passes through the dead section.

[0052] The sine calculation unit 609 calculates a sine value sinθ using the voltage phase θ. The multiplication unit 610 multiplies the output of the sine calculation unit 609 by the rated voltage amplitude V s *. The nominal voltage amplitude V s * is the nominal value of the carriage voltage V1. The multiplication result is called the PLL voltage V 2p issued.

[0053] Switch 611 is normally open (OFF) during normal operation, is switched on during a power-off period, and is returned to an OFF state after the rail vehicle has passed through the dead zone. During normal operation, switchgear 103 is closed and the voltage V b , which is output from the gain application unit 601, is therefore used as the signal that serves as the basis of the counter voltage command value V2*. Meanwhile, during the power-off period, the PLL voltage V2p output from the multiplier unit 610 is used as the signal serving as the basis of the counter voltage command value V2*.

[0054] Finally, the output of switch 611 is input to BPF 612. BPF 612 extracts a fundamental component and outputs the fundamental component as the counter voltage command value V2*. Since the carriage voltage V1 has superimposed harmonics as a result of the operation of converter 210, BPF 612 is provided to remove the superimposed harmonic components.

[0055] It can be noted that the switch 611 is switched from an ON state to an OFF state at a time after the phase of the reverse voltage command value V2* matches the phase of the car voltage V1 and also after the switchgear 103 is closed. It can be noted that the reverse voltage command value V2* does not undergo any significant change before and after the switch 611 is switched because the phase of the reverse voltage command value V2* already matches the phase of the car voltage V1, even if the switch 611 is turned off after the switchgear 103 is closed.

[0056] A method for determining completion of phase synchronization will also be described below. The counter voltage command value V2* is a sine wave including only the fundamental wave component with a small disturbance as a result of the processing of the BPF 612. The counter voltage command value V2* thus changes its sign every half period of the fundamental wave. The carriage voltage V1 at the moment of this change is monitored for sign, and completion of phase synchronization is determined when the instantaneous voltage thereof is less than or equal to a predetermined value. Instead of this method, completion of phase synchronization could be determined when a difference between a slope of the carriage voltage V1 and a slope of the counter voltage command value V2* at the moment of a change in sign is less than or equal to a predetermined value.It should be noted that the predetermined value used to determine the completion of phase synchronization can be determined by the magnitude of an inrush current allowed for the main transformer 104.

[0057] The operation of the switching unit 820 of the counter voltage calculation unit 501, which differs from the above-explained operation, will be described. First, the multiplication unit 801 multiplies the output of the gain application unit 601 by the output of the sine calculation unit 609. The multiplication result is expressed below by a formula (5). Formula 5: Vb⋅sin(ω0t+θ2)=Vs*⋅(cos(θ1−θ2)−cos(2ω0t+θ1+θ2)) / 2

[0058] The right-hand side of formula (5) above represents the difference between a voltage component that varies with time and a voltage component that pulsates at an angular frequency twice the angular frequency of the voltage. The LPF 802 simply retains the first component and removes the second component. The LPF 802 can be any LPF capable of sufficiently removing the component with an angular frequency of 2ω0, such as the LPF 604. The LPF 802 can thus be similar to the LPF 604.

[0059] The LPF 802 provides an output of V s*{cos(θ1-θ2)} / 2. The difference θ1-θ2 corresponds to the estimated phase difference Δθ described above. If the estimated phase difference Δθ is greater than or equal to -90[°] but less than 90[°], the output of the LPF 802 has a positive value. If the estimated phase difference Δθ is either less than -90[°] or greater than 90[°], the output of the LPF 802 has a negative value. Accordingly, whether one of the carriage voltage phase θ1 and the counter voltage phase θ2 is leading the other can be determined from the sign of the output result of the LPF 802. The carriage voltage phase θ1 is defined here as “leading” if the carriage voltage phase θ1 is greater than the counter voltage phase θ2, i.e., if the estimated phase difference Δθ is positive; and the carriage voltage phase θ1 is defined here as “lagging” if the carriage voltage phase θ1 is smaller than the counter voltage phase θ2, i.e.when the estimated phase difference Δθ is negative. The sign determination unit 803 performs the above determination process, interpreting the estimated phase difference Δθ as being from -180[°] to +180[°], inclusive. Note that when the estimated phase difference Δθ is 0, the sign determination unit 803 determines the estimated phase difference Δθ as either positive or negative.

[0060] The multiplier unit 804 multiplies a fixed value Δω0 of the frequency correction quantity by either "+1" or "-1," that is, by the determination result provided by the sign determination unit 803. The output of the multiplier unit 804 is input to the switch 805. It should be noted that the fixed value Δω0 of the frequency correction quantity is a positive value and is set to a value less than or equal to a frequency change amount allowable for the auxiliary power supply device 107.

[0061] The switch 805 determines the frequency correction quantity Δω. More specifically, this means that 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 application unit 605 is used as the frequency correction quantity Δω. Alternatively, when the output of the LPF 802 is negative, that is, when the estimated phase difference Δθ is greater than 90°, the switch 805 is switched to receive an input from the minus (-) terminal, thus taking the output from the multiplication unit 804. In this case, the frequency correction quantity Δω, which is the output of the switch 805, becomes either Δω=+ω0 or Δω=-ω0, depending on the determination result provided by the sign determination unit 803. For the purpose of further reducing the time required for phase synchronization, the sign of the frequency correction quantity Δω is switched.It should be noted that when the estimated phase difference Δθ is 90[°], the switch 805 could take either the output of the gain application unit 605 or the output of the LPF 802.

[0062] The foregoing control is considered as an overview of an operation of the counter-voltage calculation unit 501. When the carriage voltage phase θ1 leads the counter-voltage phase θ2 by a value ranging from 90° to 180°, the counter-voltage calculation unit 501 is operated to increase the frequency of the counter-voltage command value V2* with Δω=+ω0, that is, the sign of the frequency correction quantity Δω is a plus sign. Alternatively, when the carriage voltage phase θ1 lags the counter voltage phase θ2 by a value ranging from 90[°] to 180[°], the counter voltage calculation unit 501 is operated to decrease the frequency of the counter voltage command value V2* with Δω=-ω0, that is, the sign of the frequency correction quantity Δω is a minus sign.

[0063] An advantage provided by using the counter voltage calculation unit 501 according to the embodiment will be described next. Fig. 9 is a diagram for describing an effectiveness of reducing the time required for phase synchronization when the counter voltage calculation unit 501 according to the present embodiment is used.

[0064] In Fig. 9 represents the horizontal axis, similar to Fig. 7, the actual voltage phase difference θ1-θ2 and the vertical axis represents the time required for phase synchronization, that is, the time it takes for PLL operation to end and phase synchronization to be completed. In addition, the solid line in Fig. 9 shows the time required for phase synchronization when the present technique is used, and the dashed line represents the time required for phase synchronization in the comparative example. The term "comparative example" shall refer to the counter voltage calculation unit 501 used in Fig. 8, without the functionality of the switching unit 820, ie without a functionality of switching the sign of the frequency correction quantity Δω depending on the estimated phase difference Δθ. It should be noted that the meaning of the straight line separated by a dot-dash line in Fig. 9 is represented, will be described later.

[0065] A description of the Fig. 9 is based on the assumption that the carriage voltage is 50 [Hz], that the permissible frequency of the voltage supplied to the auxiliary power supply device 107 is up to 50±3 [Hz], and that Δω0=3×2π [rad / s]. In addition, the gain K PLL , which is specified by the gain application unit 605, K PLL =Δω0 / V s * so that the frequency correction quantity Δω at Δθ=90° is equal to Δω0.

[0066] Furthermore, the actual voltage phase difference θ1-θ2, which is along the horizontal axis of the Fig. 9, an actual voltage phase difference at a time when the carriage voltage V1 is restored and the switch 606 is switched to an ON state. Furthermore, the time in Fig. 9, at which the actual voltage phase difference θ1-θ2 reaches or falls below 0.1 [rad], is defined as the time of completion of phase synchronization.

[0067] In the comparison example, the time required for phase synchronization increases sharply as the actual voltage phase difference θ1-θ2 approaches 180°. Specifically, phase synchronization takes an infinite time at 180°, which means phase synchronization is impossible. In contrast, the present technique enables phase synchronization to be completed in less than 0.4 [s] even when the actual voltage phase difference θ1-θ2 is 180°.

[0068] It should be noted that the above description was made so as to switch the sign of the frequency correction quantity Δω based on the determination result provided by the sign determination unit 803 in order to further reduce the time required for phase synchronization. For the sign determination unit 803, the sign changes at ±90[°], which means that the threshold for switching the sign of the frequency correction quantity Δω is ±90[°]. Meanwhile, this threshold does not have to be ±90[°], but it could be set to ±150[°], for example. The reason for this will be explained next with reference to Fig. 9 are described.

[0069] In Fig. In Figure 9, a dot-dash straight line connects the origin (0, 0) and a point A on the dashed line, which is given as the comparative example. This straight line, which is tangent at point A, represents the smallest slope of straight lines connecting the origin (0, 0) to any point on the dashed line. Furthermore, the actual voltage phase difference θ1-θ2 corresponding to point A is approximately 157°. The slope of the straight line, given by "time required for phase synchronization (vertical axis)" / "actual voltage phase difference (horizontal axis)", increases steeply after point A. An increase in the slope of the straight line means an increase in the time required for phase synchronization. Thus, an angle of 150° corresponding to point B, which is located near point A and to the left of point A, is set as a threshold for switching the sign.It should be noted that the . Fig. 9 is bilaterally symmetrical, and the threshold of the actual voltage phase difference θ1-θ2 is thus set to -150[°] in the negative part.

[0070] Thus, the switching unit 820 of the counter voltage calculation unit 501 compares the absolute value of the estimated phase difference Δθ with a threshold. If the absolute value of the estimated phase difference Δθ is greater than the threshold and if the estimated phase difference Δθ has a positive sign, the switching unit 820 switches the frequency correction quantity Δω to a positive value. Furthermore, when comparing the absolute value of the estimated phase difference Δθ with the threshold, the switching unit 820 switches the frequency correction quantity Δω to a negative value if the absolute value of the estimated phase difference Δθ is greater than the threshold and if the estimated phase difference Δθ has a negative sign.

[0071] In the previous control, a comparison between the threshold of ±90° for switching the sign of the frequency correction quantity Δω and the threshold of ±150° for switching the sign of the frequency correction quantity Δω shows that the former allows the use of functionality common to an existing control device. The former is therefore advantageous over the latter in that the control system can be configured more simply. The slope of the straight line in Fig. 9, which is a value calculated by "actual voltage phase difference (horizontal axis)" / "time required for phase synchronization (vertical axis)" when the vertical axis and the horizontal axis are viewed in reverse, corresponds to a difference between the average frequency with respect to the time of PLL operation and the frequency of the carriage voltage, that is, the average frequency correction quantity with respect to the time of PLL operation. Thus, the latter is advantageous in reducing the time required for phase synchronization while reducing an increase in the average frequency correction quantity during PLL operation.

[0072] Specific operating waveforms are described next with reference to the drawings of the Fig. 10 to 15 are described. Fig. 10 is a diagram illustrating voltage waveforms and current waveforms of a main part in the comparative example when the actual voltage phase difference is 180[°]. Fig. 11 is a diagram illustrating PLL operation waveforms in the comparative example when the actual voltage phase difference is 180[°]. Fig. 12 is a diagram illustrating voltage waveforms and current waveforms of a main part provided by the present technique when the actual voltage phase difference is 180[°]. Fig. 13 is a diagram illustrating PLL operating waveforms provided by the present technique when the actual voltage phase difference is 180[°]. Fig. 14 is a diagram illustrating voltage waveforms and current waveforms of the main part provided by the present technique when the actual voltage phase difference is 150[°]. Fig. 15 is a diagram illustrating PLL operating waveforms provided by the present technique when the actual voltage phase difference is 150[°].

[0073] Everyone who Fig. 10, Fig. 12 and Fig. Fig. 14 illustrates, in order from top to bottom, waveforms of (a) a carriage voltage V1, (b) a converter AC current, (c) a reception voltage of the auxiliary power supply device 107, and (d) a load current of the auxiliary power supply device 107. In addition, each of the Fig. 11, Fig. 13 and Fig. 15, in order from top to bottom, waveforms (a) of a turn-on signal of the switch 606 and a synchronization determination result, (b) a carriage voltage V1 and a PLL voltage V 2p , (c) a counter voltage command value V2* and (d) a frequency of the counter voltage command value V2*.

[0074] Fig. 10 and Fig. 11 each illustrates simulation results of the comparative example when the actual voltage phase difference is 180[°]. Fig. 12 and Fig. 13 each illustrates simulation results obtained using the present technique when the actual voltage phase difference is 180[°]. Fig. 14 and Fig. 15 each illustrates simulation results obtained by using the present technique when the actual voltage phase difference is 150[°].

[0075] In part (a) of each of the Fig. 11, Fig. 13 and Fig. 15, the thick dashed line represents a turn-on signal for the switch 606, and the thick solid line represents a synchronization determination result. In addition, in part (b) of each of the Fig. 11, Fig. 13 and Fig. 15 the thick dashed line represents the carriage voltage V1 and the thin solid line represents the PLL voltage V 2p . It should be noted that the information provided in part (a) of each of the Fig. 10, Fig. 12 and Fig. 14 illustrates the carriage voltage V1 and the PLL voltage V 2p , which in part (b) of each of the Fig. 11, Fig. 13 and Fig. 15, are each a secondary equivalent value.

[0076] One can see that, as in Fig. 11(b) illustrates that the operation in the comparative example where the actual voltage phase difference is 180[°] fails to achieve synchronization between the carriage voltage V1 and the PLL voltage V 2p to complete even if a lapse of 0.4 [s] after the carriage voltage V1 is restored at time 4.5 [s]. The reason is that the PLL does not work well with a small value output from the gain application unit 605 because the estimated phase difference Δθ is estimated to be substantially zero when the actual voltage phase difference is 180 [°], as described with reference to Fig. 7 described.

[0077] In contrast, it is clear that, as in Fig. 13(b) illustrates the operation of the present technique where the actual voltage phase difference is 180[°], the phase adjustment between the carriage voltage V1 and the PLL voltage V 2pbegins immediately after the car voltage V1 is restored at time 4.5 [s], so that the phase synchronization is completed in approximately 0.3 [s]. Upon completion of the phase synchronization, a turn-on signal is sent to the switchgear 103. The waveform of the received voltage of the auxiliary power supply device 107, which is Fig. 12(c) indicates that a voltage is constantly supplied, although the waveform until the switchgear 103 is turned on and the waveform after the switchgear 103 is turned on differ from each other in terms of harmonic components originating from the converter 210 and the auxiliary power supply device 107. It can also be seen that, as in Fig. 13(d), the frequency of the injected voltage falls within the range of 50±3 [Hz] as initially designed.

[0078] In addition, the exemplary operating modes described in the Fig. 10 to 13, synchronization by increasing the frequency correction quantity Δω, whereas the exemplary modes of operation in the Fig. 14 and Fig. 15 enable synchronization by reducing the frequency correction quantity Δω. This means that it can be seen that the method of the present technique achieves suitable operation by not only increasing the frequency correction quantity Δω but also decreasing it.

[0079] It should be noted that although the above description was provided in the form of phase synchronization between the converter voltage phase and the car voltage phase when a rail vehicle passes through a dead section, the application is not limited to this example. For example, the present technique is also applicable to phase synchronization in the event of a sudden car line power failure. The above advantage can also be achieved even in such a case.

[0080] As described above, in the railway vehicle power converter device according to the embodiment, the control device includes a converter control unit that performs control, by controlling a converter, to supply regenerative power generated by a traction motor to a second power converter device via a main transformer during a power-off period, wherein the power-off period is a period during which no electric power is supplied from a car 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 serving as a reference for current control of the converter based on a detection value of a car voltage.The voltage phase estimation unit estimates, based on the reference voltage, a phase of an AC voltage applied to the second power conversion device during the no-power period. 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, which is a phase of a first voltage, and a second phase, which is a phase of a second voltage. The first voltage is a carriage voltage detected by a voltage detector after the no-power period ends. The second voltage is an AC voltage estimated by the voltage phase estimation unit based on a carriage voltage detected by the voltage detector before the no-power period begins.The switching unit switches a sign of a frequency correction quantity for correcting a frequency of the second voltage based on an estimated phase difference representing an estimated value of the phase difference. The railway vehicle power converter device configured as described above can solve the problem of the estimated phase difference being smaller than the actual one and requiring time for phase synchronization when the actual voltage phase difference is large. This enables a reduction in the increase in the time required for phase synchronization even when the car voltage frequency deviates from its rated value.It should be noted that the term ‘non-powered period’ as used here could refer to a period comprising the period during which the rolling stock traverses the dead section and its preceding and subsequent periods, or a period from a sudden power failure of the rolling stock line until such sudden power failure is restored.

[0081] In the above configuration, the converter control unit increases the frequency of the second voltage when the estimated phase difference has a positive sign, and decreases the frequency of the second voltage when the estimated value of the estimated phase difference has a negative sign. Furthermore, the switching unit compares an absolute value of the estimated phase difference with a predetermined threshold, and when the absolute value of the estimated phase difference is greater than the threshold and when the estimated phase difference has a positive sign, the switching unit switches the frequency correction quantity to a positive value.Furthermore, the switching unit compares the absolute value of the estimated phase difference with the predetermined threshold. If the absolute value of the estimated phase difference is greater than the threshold and if the estimated phase difference has a negative sign, the switching unit switches the frequency correction quantity to a negative value. Such a control system is highly compatible with an existing control system and can thus be easily integrated into it.

[0082] It should be noted that in the above control, the threshold for comparison with the absolute value of the estimated phase difference can be set to, for example, 90° or 150°. Setting the threshold to 90° can simplify the configuration of the control system. Alternatively, setting the threshold to 150° can reduce the time required for phase synchronization and reduce the increase in the average or mean frequency correction quantity during PLL operation.

[0083] Finally, a hardware configuration for implementing the functionality of the converter control unit 242 described above will be described with reference to the Fig. 16 and Fig. 17 are described. Fig. 16 is a block diagram illustrating an example of a hardware configuration for implementing the functionality of the converter control unit 242 in the embodiment. Fig. 17 is a block diagram illustrating another example of a hardware configuration for implementing the functionality of the converter control unit 242 in the embodiment.

[0084] If part or all of the functionality of the converter control unit 242 is to be implemented in the embodiment, the hardware configuration may be as shown in Fig. 16, a processor 300 for performing a calculation, a memory 302 for programming a program to be read by the processor 300, and an interface 304 for inputting and outputting signals.

[0085] The processor 300 represents a computing device. The processor 300 could be a computing device called a microprocessor, microcomputer, central processing unit (CPU), or digital signal processor (DSP). Furthermore, the memory 302 can be, for example, a non-volatile or volatile semiconductor memory, such as a random access memory (RAM), a read-only memory (ROM), a flash memory, an erasable programmable ROM (EPROM), or an electrically erasable programmable ROM (EEPROM) (registered trademark); a magnetic disk, a floppy disk, an optical disk, a compact disc, a minidisc, or a digital versatile disc (DVD). It should be noted that the memory 302 could be a combination of multiple storage devices, such as a RAM and an EEPROM.

[0086] Memory 302 stores a program for implementing the functionality of converter control unit 242 in the embodiment. Processor 300 can perform the above-described processing by providing and receiving necessary information via interface 304, executing a program stored in memory 302, and referencing a table stored in memory 302. The result of a calculation performed by processor 300 can be stored in memory 302.

[0087] In addition, when part of the functionality of the converter control unit 242 is to be implemented in the embodiment, a processing circuit 303 may be used which is shown in Fig.17. Processing circuitry 303 may be a single circuit, a set of multiple circuits, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a combination thereof. Information input to processing circuitry 303 and information to be output from processing circuitry 303 may be obtained via interface 304.

[0088] It should be noted that the processing of the converter control unit 242 could be performed in such a manner that part of the processing is performed by the processing circuit 303 and processing not performed by the processing circuit 303 is performed by a combination of the processor 300 and the memory 302.

[0089] The configurations described in the foregoing embodiment are merely examples. These configurations may be combined with other known technology, and a part of such configurations may be omitted and / or modified without departing from the spirit. List of reference symbols

[0090] 100 Carriage line; 101 Power input unit; 102 ACPT; 103 Switchgear; 104 Main transformer; 105 Main converter device; 106 Traction motor; 107 Auxiliary power supply device; 141 Primary winding; 142 Secondary winding; 143 Tertiary winding; 210 Converter; 211, 231 Primary terminal; 212, 232 Secondary 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 Counter voltage calculation unit; 502 Voltage phase estimation unit; 503 Current control unit; 504 Voltage command calculation unit; 505 Converter control signal generation unit; 601, 605 Gain application unit; 602 Cosine calculation unit; 603, 610, 801, 804 Multiplication unit; 604, 802 LPF; 606, 611, 805 Switch; 607 Addition unit; 608 Integration unit; 609 Sine calculation unit; 612 BPF;803 Sign determination unit; 810 Phase difference estimation unit; 820 Switching unit.; QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 6510060

[0005]

Claims

[1] A railway vehicle power conversion device to be installed in a railway vehicle, the railway vehicle comprising: a main transformer having a primary winding connected to a car line via a power receiving unit; a switchgear electrically disconnecting or connecting the main transformer to the car line; and a voltage detector disposed between the car line and the switchgear for detecting a car voltage applied by the car line, the railway vehicle power conversion device comprising: a first power conversion device; a second power conversion device; and a control device, the first power conversion device being connected to a secondary winding of the main transformer and being connected to a drive motor for driving the railway vehicle,wherein the first power conversion device comprises a converter for converting an AC voltage applied via the main transformer into a DC voltage, wherein the second power conversion device is connected to a tertiary winding of the main transformer to supply electrical power to an auxiliary device installed in the rail vehicle, wherein the control device controls operations of the switchgear and the first and second power conversion devices, wherein the control device comprises a converter control unit for performing control, by controlling the converter, to supply regenerative power generated by the drive motor to the second power conversion device via the main transformer during a power-free period, wherein the power-free period is a period during which no electrical power is supplied from the car line, the converter control unit comprises: a reference voltage calculation unit for calculating a reference voltage based on a detection value of the carriage voltage, the reference voltage serving as a reference for current control of the converter; and a voltage phase estimation unit for estimating, based on the reference voltage, a phase of an AC voltage applied to the second power conversion device during the power-free period, and The reference voltage calculation unit includes: a phase difference estimation unit for estimating a phase difference between a first phase and a second phase, wherein the first phase is a phase of a first voltage, wherein the second phase is a phase of a second voltage, wherein the first voltage is a carriage voltage detected by the voltage detector after the power-free period ends, wherein the second voltage is the AC voltage estimated by the voltage phase estimation unit based on a carriage voltage detected by the voltage detector before the power-free period begins; and a switching unit for switching a sign of a frequency correction quantity for correcting a frequency of the second voltage based on an estimated phase difference, wherein the estimated phase difference is an estimated value of the phase difference. [2] A railway vehicle power conversion device according to claim 1, wherein the powerless period is a period including a period during which the railway vehicle passes through a dead section and a preceding and succeeding period. [3] The railway vehicle power conversion device according to claim 1, wherein the powerless period is a period of time from a sudden power failure of the car line until the sudden power failure is restored. [4] A rail vehicle power converter device according to any one of claims 1 to 3, wherein the converter control unit the frequency of the second voltage increases if the estimated phase difference has a positive sign, and the frequency of the second voltage is reduced if an estimated value of the estimated phase difference has a negative sign. [5] A railway vehicle power converter device according to any one of claims 1 to 4, wherein the switching unit compares an absolute value of the estimated phase difference with a predetermined threshold, and when the absolute value is larger than the threshold and when the estimated phase difference has the positive sign, the switching unit switches the frequency correction quantity to a positive value. [6] A railway vehicle power converter device according to any one of claims 1 to 4, wherein the switching unit compares an absolute value of the estimated phase difference with a predetermined threshold, and when the absolute value is greater than the threshold and when the estimated phase difference has a negative sign, the switching unit switches the frequency correction quantity to a negative value. [7] A rail vehicle power converter device according to claim 5 or 6, wherein the threshold is 90°. [8] A rail vehicle power converter device according to claim 5 or 6, wherein the threshold is 150°.

Images