JP2017046468A - Power converter for rolling stock - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance acceleration performance and regeneration brake force in the high speed region of a rolling stock, even with a small storage capacity of a power storage device.SOLUTION: A power converter for rolling stock includes an inverter device for obtaining a DC power from at least one of a DC power supply and a power storage device, and converting it into a three-phase AC power for driving an AC motor, and when the rotational speed of the AC motor is lower than a reference frequency, obtaining a DC power from the DC power supply and converting it into a three-phase AC power, otherwise obtaining a DC power from the DC power supply and power storage device, and converting it into a three-phase AC power for driving the AC motor.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power conversion device for a railway vehicle that obtains electric power from at least one of a DC power source and a power storage device and drives an AC motor.

  In recent years, there has been an active movement in railway vehicles to use energy storage devices composed of energy storage means such as storage batteries and electric double layer capacitors, and to achieve further energy savings by improving the efficiency of the equipment that makes up railway vehicles. It has become.

  One of the methods of utilizing an energy storage device is expansion of regeneration capacity. In regenerative braking, the induced voltage of the AC motor needs to be lower than the power supply voltage.Therefore, in the high speed range where the induced voltage is higher than the power supply voltage, the field is weakened and the induced voltage is controlled to be lower than the power supply voltage. ing. For this reason, the electric braking force is insufficient in the high speed range, and supplementation by an air brake is performed.

  On the other hand, Non-Patent Document 1 reports a technique for improving acceleration performance and regenerative braking force in a high speed range by connecting a DC power source and an energy storage device in series and boosting the voltage on the DC side of the inverter device. ing.

  By applying this technology to a railway vehicle, it is possible to improve the acceleration / deceleration performance of the vehicle and further increase energy saving by increasing the electric power returned to the overhead line by increasing the regenerative braking force. Further, since the amount of air brake used in the high speed range can be suppressed, wear of the brake shoes is reduced, and an effect of reducing maintenance costs can be obtained.

Shimada et al .: “Basic characteristics of non-uniform voltage type three-level inverter with storage elements connected in series on the DC input side” IEEE Japan MD-11-14 RM-11-35 2011

  Railroad vehicles reach their maximum speed with a single acceleration and stop with a single brake unless otherwise limited by track shape. Therefore, since the discharge time or the charging time from the energy storage device becomes long, it is necessary to sufficiently increase the mounted capacity in order to effectively use the energy storage device.

  However, in a railway vehicle, there is a limit to the capacity of an energy storage device that can be mounted due to restrictions on equipment. Therefore, when the technique of Non-Patent Document 1 is applied to a railway vehicle, it is necessary to control charging / discharging of the power storage device so as to obtain a high effect with a small power storage capacity. Non-Patent Document 1 does not specifically describe such a problem.

  A power conversion device for a railway vehicle according to the present invention includes an inverter device that obtains DC power from at least one of a DC power source and a power storage device, converts the DC power into three-phase AC power, and drives an AC motor. When the rotational speed is lower than the reference frequency, DC power is obtained from the DC power source and converted into three-phase AC power. When the rotational speed of the AC motor is higher than the reference frequency, the DC power is supplied from the DC power source and the power storage device. And converting it into three-phase AC power to drive the AC motor.

  According to the power conversion device for a railway vehicle of the present invention, acceleration performance and regenerative braking force in a high speed region of the railway vehicle (AC motor) can be improved even with a small storage capacity of the power storage device.

FIG. 1 is a configuration diagram of the power conversion apparatus according to the first embodiment. FIG. 2 is a diagram illustrating the relationship between the modulated wave Vc and the triangular wave carrier at low speeds in the first and second embodiments. FIG. 3 is a diagram illustrating the relationship between the modulated wave Vc and the triangular wave carrier at high speeds in the first and second embodiments. FIG. 4 is a diagram illustrating another aspect of the relationship between the modulated wave Vc and the triangular wave carrier in the first and second embodiments at high speed. FIG. 5 is a configuration diagram of the power conversion apparatus according to the second embodiment. FIG. 6 is a configuration diagram of the power conversion apparatus according to the third embodiment. FIG. 7 is a diagram illustrating the relationship between the modulated wave Vc and the triangular wave carrier at the low speed of the third embodiment. FIG. 8 is a diagram illustrating the relationship between the modulated wave Vc and the triangular wave carrier at high speed in the third embodiment. FIG. 9 is a configuration diagram of the power conversion apparatus according to the fourth embodiment. FIG. 10 is a configuration diagram of another power conversion apparatus according to the fourth embodiment. FIG. 11 is a diagram illustrating a relationship between the modulated wave Vc and the triangular wave carrier during operation of the fourth embodiment.

  Examples 1 to 4 will be described below with reference to the drawings as embodiments of the present invention.

  A power conversion apparatus for a railway vehicle according to a first embodiment of the present invention will be described with reference to FIGS. First, the configuration of the power converter for a railway vehicle of the present invention will be described, and then the operation of the power converter will be described.

  FIG. 1 is a configuration diagram of a power conversion apparatus according to Embodiment 1 of the present invention. Inverter device 1 surrounded by a broken line in FIG. 1 converts DC power output from DC power supply 2 and power storage device 3 into three-phase AC power to drive AC motor 5.

  In general, the DC power source 2 is configured to connect to a DC overhead line via a pantograph as a current collector, to obtain DC power by a third rail system, or to obtain AC power by non-contact power transmission and a rectifier The structure etc. which convert into direct-current power by using are used.

  Moreover, as the AC motor 5, an induction motor or a permanent magnet type synchronous motor is used. Although FIG. 1 shows a configuration in which the inverter device 1 drives one AC motor 5, the inverter device 1 may have a configuration in which a plurality of AC motors 5 are driven.

  The power storage device 3 is composed of a secondary battery or a capacitor, discharges electric power when the vehicle is powered, and charges electric power when the vehicle is regenerated. The voltage Eb of the power storage device 3 is set to a value lower than the voltage Es of the DC power supply 2.

  The inverter device 1 includes first to twelfth current control means 4A to twelfth current control means 4L. Each current control means has a current control element capable of conducting or interrupting a current flowing from the high voltage side to the low voltage side, and this current. It is composed of a combination of diodes that can conduct current in the opposite direction to the control element.

  In general, as the current control element, a power semiconductor element such as an IGBT (Insulated Gate Bipolar Transistor) or a power MOSFET (Metal Oxide Semiconductor Field Effect Transistor, metal oxide semiconductor field effect transistor) is used. .

  Many of these power semiconductor devices are manufactured using silicon as a material, but in recent years, wide band gap semiconductors manufactured using SiC (silicon carbide) and GaN (gallium nitride) have also increased. This contributes to the reduction of system loss. Therefore, the current control element may be one using a wide bandgap semiconductor made of SiC or GaN.

Next, the operation | movement aspect of the inverter apparatus 1 is demonstrated.
First, an operation mode when the rotational speed Fr of the AC motor 5 is lower than the reference frequency Fr0 will be described with reference to FIG. FIG. 2 shows the relationship between the modulated wave Vc obtained by normalizing the AC voltage command value with the voltage on the DC side of the power converter and the triangular wave carriers (A, B) for one phase of the three-phase AC. Yes.

  For the current control means 4A to 4L constituting the inverter device 1 of FIG. 1, based on the magnitude relationship between the modulated wave Vc and the carrier, if the modulated wave Vc is larger than the carrier, an on command is issued, and the modulated wave Vc is If it is smaller than the carrier, an off command is issued. Among these, the current control means 4B, 4D, 4F, 4H, 4J and 4L are controlled by comparing the modulated wave Vc with the carrier A whose amplitude is the voltage Es of the DC power supply 2, and the modulated wave Vc and the amplitude are stored in the power storage device. The current control means 4A, 4C, 4E, 4G, 4I and 4K are controlled by comparison with the carrier B having a voltage Eb of 3.

  Normally, the modulation wave Vc of the three-level power converter is centered on (Es + Eb) / 2, which is half the total value of the center value of the input voltage, that is, the voltage Es of the DC power supply 2 and the voltage Eb of the power storage device 3. Generated. In this case, when the amplitude of the modulation wave Vc exceeds (Es + Eb) / 2, charging / discharging of the power storage device 3 is started, and thus the operation time becomes long.

  Therefore, in the present invention, when the rotational speed Fr of the AC motor 5 is lower than the reference frequency Fr0, a modulation wave is generated around the half Es / 2 of the voltage Es of the DC power supply 2, and the modulation wave Vc is within the range of the carrier A. Create to fit. Thereby, the AC motor 5 can be driven only by the power supply from the DC power supply 2 until the amplitude of the modulated wave Vc exceeds Es / 2.

  Next, an operation mode when the rotation speed Fr of the AC motor 5 is higher than the reference frequency Fr0 will be described with reference to FIG. FIG. 3 also shows the relationship between the modulated wave Vc and the triangular wave carriers (A, B) for one phase of the three-phase alternating current.

  As described above, the modulation wave of the three-level power converter is centered on (Es + Eb) / 2, which is half the total value of the center value of the input voltage, that is, the voltage Es of the DC power supply 2 and the voltage Eb of the power storage device 3. Is generated. Thereby, since the input voltage of the inverter apparatus 1 becomes higher than the voltage Es of the DC power supply 2, the upper limit value of the induced voltage of the AC motor 5 can be increased, and the acceleration performance and the regenerative braking performance in the high speed range can be improved. Is possible.

  Here, in the AC motor 5, the transition from the state A to the state B is described with the state A when the rotational speed Fr is lower than the reference frequency Fr0 and the state B when the rotational speed Fr is higher than the reference frequency Fr0. .

  The reference frequency Fr0 is set so that the amplitude of the modulated wave Vc is equal to or less than Es / 2. At this time, the reference frequency Fr0 may be continuously changed according to the voltage Es of the DC power supply 2. For example, it is assumed that the voltage Es of the DC power source 2 increases immediately after the rotational speed Fr of the AC motor 5 exceeds the reference frequency Fr0 and shifts from the state A to the state B. At this time, since the reference frequency Fr0 also increases, the rotation speed Fr may become lower than the reference rotation speed Fr0, and the state B returns to the state A. As described above, depending on the fluctuation of the voltage Es of the DC power supply 2, it is conceivable that the state B and the state A are repeated in a short cycle, which may cause the operation to become unstable.

  Therefore, in order to eliminate this instability, when the rotational speed Fr exceeds the reference frequency Fr0 and transitions from the state A to the state B and then returns from the state B to the state A, the rotational speed Fr is greater than the reference frequency Fr0. A hysteresis may be given to the reference frequency, for example, when the frequency falls below the low reference frequency Fr1.

  Alternatively, as shown in FIG. 4, after the amplitude of the modulated wave Vc becomes Es / 2, the central axis of the modulated wave Vc may vary depending on the rotational speed Fr of the AC motor 5. At this time, when the rotation speed of the AC motor 5 in which the amplitude of the modulation wave Vc is (Es + Eb) / 2 is Fr2, when the rotation speed Fr of the AC motor 5 is between the reference frequencies Fr0 and Fr2, the modulation wave Vc The central axis may be linearly changed according to the rotational speed Fr of the AC motor 5. Further, when the rotational speed Fr of the AC motor 5 is between the reference frequencies Fr0 and Fr2, the central axis of the modulated wave Vc may be changed stepwise. There is no limitation on the number of stairs at this time.

  Here, since the rotational speed Fr of the AC motor is substantially the same value as the inverter frequency, instead of the rotational speed Fr of the AC motor, the speed of the railway vehicle is proportional to the inverter frequency or the rotational frequency of the AC motor. You may control according to it.

  As described above, according to the power conversion device for a railway vehicle according to the first embodiment, the acceleration performance and the regenerative braking force in the high speed region are improved with a small storage capacity while suppressing the amount of the storage device used to the minimum. It becomes possible to make it.

  FIG. 5 is a configuration diagram of a power conversion device for a railway vehicle according to a second embodiment of the present invention. In the present invention, power is supplied from the DC power source 2 in the constant speed region, and power is supplied from both the DC power source 2 and the power storage device 3 in the high speed region. The device 1 uses a three-level circuit. Further, the AC motor 5 driven by the inverter device 1 is one in FIG. 5, but may be a plurality.

  In addition to the T-shaped circuit configuration shown in FIG. 1, the three-level circuit includes a three-level circuit configuration in which four current control units are connected in series. FIG. 5 is a diagram showing a configuration in the case of using a three-level inverter in which four current control means are connected in series in the railway vehicle inverter device 1 shown in FIG. In the configuration shown in FIG. 5, clamp diodes 6 </ b> A to 6 </ b> F are provided in the inverter device 1. The relationship between the modulated wave Vc, the carrier A whose amplitude is the voltage Es of the DC power supply 2, the carrier B whose amplitude is the voltage Eb of the power storage device 3, and the current control means controlled by these comparison results is shown in Example 1. Is the same as

  In the configuration shown in FIG. 5, two current control means are connected in series between the output part of each phase of the inverter device 1 and the N side of the input part. Therefore, when the AC motor 5 is driven only by the power supply from the DC power source 2 in the second embodiment, the current control units 4D, 4H, and 4L controlled in conjunction with the current control units 4B, 4F, and 4J are turned on. Then, the current control means 4C, 4G, and 4K must be turned on simultaneously. On the other hand, since the current control means 4C, 4G and 4K are controlled in conjunction with the current control means 4A, 4E and 4I, the current control means 4A, 4E and 4K are controlled when the current control means 4C, 4G and 4K are off. Since 4I is turned on, the power storage device 3 is also supplied with power. Therefore, it is desirable that the current control units 4C, 4G, and 4K are always in a conductive state only when the AC motor 5 is driven only by power supply from the DC power source 2.

  In addition, the power supplied from the DC power supply 2 is supplied via the clamp diodes 6A, 6C, and 6E, so that a voltage drop due to the forward voltage of the diode occurs. Therefore, when setting the reference frequency Fr0, it may be set in consideration of the voltage drop due to the forward voltage.

  According to the power conversion device for a railway vehicle according to the second embodiment described above, it is possible to improve acceleration performance and regenerative braking force in a high speed region with a small power storage capacity while minimizing the usage amount of the power storage device. It becomes possible.

  FIG. 6 is a configuration diagram of a power conversion device for a railway vehicle according to a third embodiment of the present invention. As a method of connecting the power storage device 3, there is a method of connecting to the negative electrode side in addition to the method of connecting to the positive electrode side of the DC power source 2 as in the first embodiment shown in FIG. The third embodiment shown in FIG. 6 is configured to connect the power storage device 3 to the negative electrode side of the DC power supply 2 and is the same as the first embodiment shown in FIG. 1 except for the connection position of the power storage device 3.

  Since the negative electrode side of the DC power supply 2 is generally grounded, the ground potential is negative on the N side of the inverter device 1 shown in FIG. As a result, there is an advantage that the voltage which is a reference for ground insulation is reduced.

  The circuit configuration of the inverter device 1 shown in FIG. 6 is a T-shaped circuit configuration as in FIG. 1, but is a circuit configuration in which four current control means are connected in series as in the second embodiment shown in FIG. May be. Moreover, although the AC motor 5 driven by the inverter device 1 is one in FIG. 6, a plurality of AC motors may be used.

Next, regarding the operation mode of the inverter device 1, the configuration of the inverter device 1 is the same as that of the first embodiment shown in FIG. 1, and the operation mode is also the same as the contents described in the first embodiment.
Therefore, each description about the operation mode when the rotation speed Fr of the AC motor 5 is lower than the reference frequency Fr0 and the operation mode when the rotation speed Fr of the AC motor 5 is higher than the reference frequency Fr0 are the same as those in the first embodiment. Since it becomes the same, it abbreviate | omits. The corresponding description of the first embodiment is the above [0021] to [0031].

  However, FIG. 7 (when the rotational speed Fr of the AC motor 5 is lower than the reference frequency Fr0) and FIG. 8 (when the rotational speed Fr of the AC motor 5 is higher than the reference frequency Fr0) are for one phase of the three-phase AC. The relationship between the modulated wave Vc obtained by normalizing the AC voltage command value with the DC voltage of the power converter and the triangular wave carriers (A, B) is shown in the case of the first embodiment (FIGS. 2 and 2). 3) differs from the potential relationship (the voltage Es of the DC power supply 2 and the voltage Eb of the power storage device 3) depending on the connection method between the DC power supply 2 and the power storage device 3.

  As described above, the power conversion device for a railway vehicle according to the third embodiment also improves acceleration performance and regenerative braking force in a high speed region with a small power storage capacity while minimizing the usage amount of the power storage device. Is possible. In addition, there is an advantage that the voltage used as a reference for ground insulation can be reduced.

  FIG. 9 is a configuration diagram of a power conversion device for a railway vehicle according to a fourth embodiment of the present invention. The fourth embodiment shown in FIG. 9 has a configuration in which the DC power supply 2 is not connected and is in an open state, and the rest is the same as the first embodiment shown in FIG.

  In the railway system, there is a case where the power supply from the DC power supply 2 is not performed and an open state is caused due to several factors. For example, when a power failure occurs on the power supply side in a DC overhead line, third rail system, or non-contact power transmission, or when the vehicle is stopped in the air section in a configuration that connects to the DC overhead line via a pantograph, the vehicle is installed This is the case when all the pantographs that are running are lowered.

  At this time, a normal railway vehicle cannot travel the vehicle, but the present invention in which the power storage device 3 is mounted has an advantage that the vehicle can travel by power supply from the power storage device 3.

  The circuit configuration of the inverter device 1 shown in FIG. 9 is a T-shaped circuit configuration as in FIG. 1, but it may be a circuit configuration in which four current control means are connected in series as shown in FIG. Alternatively, as shown in FIG. 6, the power storage device 3 may be connected such that the ground potential on the N side of the inverter device 1 is negative. Moreover, although the AC motor 5 driven by the inverter device 1 is one in FIG. 6, a plurality of AC motors may be used.

  Next, the operation | movement aspect of the inverter apparatus 1 is demonstrated. In the first to third embodiments, when the rotational speed Fr of the AC motor 5 is lower than the reference frequency Fr0, only power is supplied from the DC power source 2, and when the rotational speed Fr of the AC motor 5 is higher than the reference frequency Fr0, the DC power source is used. 2 and the power supply from the power storage device 3 operate the AC motor 5, but in the fourth embodiment, DC power is supplied from the power storage device 3 regardless of the state of the rotational speed Fr of the AC motor 5.

An operation mode when the inverter device 1 shown in FIG. 9 is used will be described with reference to FIG.
For the current control means 4A to 4L, as in the case of the first embodiment shown in FIG. 1, based on the magnitude relationship between the modulated wave Vc and the carrier, an ON command is issued when the modulated wave Vc is larger than the carrier, When the modulated wave Vc is smaller than the carrier, an off command is issued.

  In the fourth embodiment, the current control means 4A, 4C, 4E, 4G, 4I, and 4K are controlled by comparing the modulated wave Vc with the carrier B having the amplitude of the voltage Eb of the power storage device 3. Then, a modulation wave is generated around half Eb / 2 of the voltage Eb of the power storage device 3, and the modulation wave Vc is created so as to be within the range of the carrier B. Thereby, AC electric motor 5 can be driven only by supplying power from power storage device 3. At this time, for the current control means 4B, 4D, 4F, 4H, 4J, and 4L, an ON command and an OFF command may be output assuming that the modulation wave Vc is always greater than the carrier A, or all may be turned off.

  According to the power conversion apparatus for a railway vehicle according to the fourth embodiment described above, even when the power supply from the DC power supply 2 is stopped, the vehicle can be driven by the power supply from the power storage device 3.

DESCRIPTION OF SYMBOLS 1 Inverter apparatus, 2 DC power supply, 3 Electrical storage apparatus, 4A 1st current control means, 4B 2nd current control means, 4C 3rd current control means, 4D 4th current control means, 4E 5th current control Means, 4F sixth current control means, 4G seventh current control means, 4H eighth current control means, 4I ninth current control means, 4J tenth current control means, 4K eleventh current control means, 4L 12th current control means, 5 AC motor, 6A 1st clamp diode, 6B 2nd clamp diode, 6C 3rd clamp diode,
6D 4th clamp diode, 6E 5th clamp diode, 6F 6th clamp diode

Claims (7)

A power supply circuit configured by connecting a DC power supply and a power storage device in series;
An inverter device for driving the AC motor by converting DC power into three-phase AC power,
The inverter device is
When the rotational speed of the AC motor is lower than a reference frequency, obtain DC power from the DC power source and convert it to three-phase AC power,
When the rotational speed of the AC motor is higher than the reference frequency, DC power is obtained from the power supply circuit and converted into three-phase AC power. It is a power converter device for rail vehicles according to claim 1,
The power conversion device for a railway vehicle, wherein the power supply circuit connects a low voltage side of the power storage device and a high voltage side of the DC power supply. It is a power converter device for rail vehicles according to claim 1,
The power conversion device for a railway vehicle, wherein the power supply circuit connects a high voltage side of the power storage device and a low voltage side of the DC power supply. A power conversion device for a railway vehicle according to any one of claims 1 to 3,
The inverter device is
When DC power is no longer supplied from the DC power source, DC power from the power storage device is converted into the three-phase AC power regardless of the rotational speed of the AC motor. Power conversion device. A power conversion device for a railway vehicle according to any one of claims 1 to 4,
The power supply circuit has a first potential on the high voltage side, a second potential on the low voltage side, and a third potential at a connection point between the DC power source and the power storage device,
The inverter device includes a current control unit that connects one of the first potential to the third potential and connects the other to the AC motor from the first potential to the third potential. Provided for each, and the current control means is selectively connected between two potentials of the first potential to the third potential, and the on / off pulse width is controlled between the two potentials. A power conversion device for a railway vehicle, wherein the power conversion device converts the power into three-phase AC power. A power conversion device for a railway vehicle according to claim 5,
The current control means is a combination of a current control element that conducts or cuts off current flowing in one direction and a rectifying element that is connected in parallel with the current control element and conducts current in the opposite direction to the current flowing through the current control element. A power conversion device for a railway vehicle, characterized by comprising: A power conversion device for a railway vehicle according to claim 6,
At least one of the current control element and the rectifying element is a wide band gap semiconductor made of silicon carbide or gallium nitride.

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