JP6762243B2 - Power converter for railroad vehicles - Google Patents

Description

The present invention relates to a power conversion device mounted on a railway vehicle.

In recent years, energy saving has been required for the realization of a low-carbon society. As energy saving in the railway field, high efficiency of power converters and electric motors is being studied. In the power conversion device, IGBTs (Insulated Gate Bipolar Transistors) and MOSFETs (Metal-Oxide-Semiconductor Field-Effective Transistors), which are voltage-driven switching elements, are applied. Power semiconductors such as IGBTs and MOSFETs can reduce switching loss due to high-speed switching operation.

Furthermore, the railway drive system uses electric brakes to realize energy saving, and regenerates electric power to the power source by converting kinetic energy into electric energy. This regenerative power is used in other vehicles and ground equipment. At this time, the insufficient braking force of the electric brake is supplemented by using a mechanical brake (hereinafter referred to as an air brake). However, when the vehicle is traveling at high speed, the output torque of the electric motor is limited, so that sufficient electric braking force cannot be obtained. Therefore, in order to improve the output torque of the electric motor when the vehicle is traveling at high speed, it has been studied to increase the voltage applied to the electric motor by using a buck-boost chopper.

Japanese Patent Application Laid-Open No. 2002-369310 (Patent Document 1) is available as a background technique in this technical field. In this publication, "a PAM control system main circuit 20 including a buck-boost DC / DC converter 12 for controlling a DC voltage from an overhead wire 18 input from a pantograph 11 and an inverter 13 as a DC / AC converter, and a railway A preset responsive braking force pattern (expected adhesive brake pattern) according to the traction motor group 14 used in a vehicle, the brake input unit 16 for inputting a brake signal, and the brake signal from the brake input unit 16. A control unit 17 that controls the PAM control system main circuit 20 based on μ is described (see summary).

JP-A-2002-369310

As a result of diligent studies on energy saving in consideration of the real-time situation of railway vehicles, the inventor of the present application has obtained the following findings.

Patent Document 1 realizes an all-electric brake by changing the deceleration according to the speed, and makes the output of the buck-boost circuit the maximum voltage at the maximum speed at which the torque of the electric motor is required, so that the speed range can be increased. The regenerative power is increased by the electric brake. However, it is not always necessary to output the maximum voltage at the maximum speed because the electric power that can be regenerated differs depending on the traveling conditions of the surrounding vehicles. That is, it is necessary to operate the buck-boost circuit by detecting the overhead line voltage and the running condition of another vehicle in real time.

An object of the present invention is to increase the amount of regenerative electric power in consideration of the surrounding conditions of a railway vehicle.

The present invention comprises a first power conversion circuit that converts DC power supplied from a DC overhead wire into DC-DC power by a plurality of switching elements, and a DC-DC output power of the first power conversion circuit by a plurality of switching elements. In a railway vehicle power conversion device having a second power conversion circuit that converts AC power to drive an electric motor, the torque of the electric motor required for braking is higher than a predetermined torque, and the voltage of the DC overhead wire is high. The present invention relates to the fact that the input voltage of the second power conversion circuit becomes higher than the voltage of the DC overhead wire when the voltage is lower than a predetermined voltage.

According to the present invention, energy saving can be realized by optimizing the operation of the buck-boost circuit for increasing the regenerative power.

It is the schematic of the electric car which concerns on Example 1. FIG. It is a circuit diagram of the drive device which concerns on Example 1. FIG. This is a regenerative characteristic of the electric motor when the DC-DC power conversion circuit according to the first embodiment operates. This is an operation flow of the DC-DC power conversion circuit according to the first embodiment. It is a timing chart when the DC-DC power conversion circuit which concerns on Example 1 operates. This is an example of the breakdown of the power consumption when the DC-DC power conversion circuit according to the first embodiment operates. It is the schematic of the electric power interchange in a plurality of vehicles which concerns on Example 2. FIG. This is an implementation example of the power conversion device according to the third embodiment.

In the embodiment, a first power conversion circuit that converts DC power supplied from a DC overhead wire into DC-DC power by a plurality of switching elements, and a DC-DC output power of the first power conversion circuit by a plurality of switching elements. It has a second power conversion circuit that converts AC power to drive the electric motor, and the torque of the electric motor required for braking is higher than the predetermined torque, and the voltage of the DC overhead wire is higher than the predetermined voltage. Discloses a power conversion device for a railroad vehicle in which the input voltage of the second power conversion circuit becomes higher than the voltage of the DC overhead line when the voltage is also low. In addition, a railway vehicle equipped with the power conversion device will be disclosed.

Further, in the embodiment, it is disclosed that the first power conversion circuit is controlled based on the information of the traveling mode of another electric vehicle. It also discloses that the traveling mode is power running or regeneration motion information.

Further, in the embodiment, it is disclosed that the switching element uses silicon or a semiconductor material having a bandgap larger than that of silicon as a base material.

Further, in the embodiment, it is disclosed that the switching element is a voltage-driven element of MOSFET or IGBT.

Further, in the embodiment, it is disclosed that the switching elements related to the upper arm and the lower arm have a 2in1 configuration enclosed in the same package.

Further, in the embodiment, it is disclosed that a plurality of switching elements related to the first power conversion circuit have a 2in1 configuration enclosed in the same package.

Further, in the embodiment, it is disclosed that the first power conversion circuit and the second power conversion circuit are mounted on the same cooler.

The above and other new features and effects will be described below with reference to the drawings. The drawings are used exclusively for understanding the invention and do not limit the scope of rights.

FIG. 1 is a schematic view of an electric vehicle according to this embodiment. The vehicle 8 is supported by a carriage 4 having wheels 3 running on the rail 2. A current collector 1 that makes electrical contact with the overhead wire 1 is installed on the upper part of the vehicle 8, and a power conversion device 6 is installed under the floor of the vehicle 8. The carriage 4 is equipped with an electric motor 5 that drives the wheels 3. In the power running operation for accelerating the electric vehicle, electric power is supplied to the vehicle 8 from the overhead wire 1 which is a power source via the current collector 7. The supplied electric power drives the electric motor 5 via the power conversion device 6, and the rotation of the wheels 3 causes the vehicle 8 to move forward or backward. Further, in the regenerative operation for decelerating the electric vehicle, the power running operation and the flow of electric power are reversed. That is, the electric power generated by the operation of the electric motor 5 as a generator is converted by the electric power conversion device 6 and then regenerated to the overhead wire 1 via the current collector 7. As an electrical ground, the negative voltage side of the power conversion device 6 is connected to the rail 2 via the wheels 3. Hereinafter, in this embodiment, an example in which the voltage of the overhead wire 1 is DC 1500 V will be described. A conductive rail or the like may be used instead of the overhead wire 1.

FIG. 2 is a circuit diagram of the drive device according to this embodiment, and shows a basic circuit configuration. The DC-DC power conversion circuit 101 includes a reactor 103 and switching elements Q1 and Q2, and the switching elements Q1 and Q2 are connected in series to form one phase. The reactor 103 is arranged so as to connect between the current collector 7 and the voltage sensor 105 and between the switching element Q1 and the switching element Q2. Further, the diodes D1 and D2 are connected in parallel to the switching elements Q1 and Q2 so that the flow directions are opposite to each other. Here, when the switching elements Q1 and Q2 are IGBTs, it is necessary to connect the diodes D1 and D2, but when the switching elements Q1 and Q2 are MOSFETs, the MOSFETs do not connect the diodes D1 and D2. Body diodes can be used. The switching element is made of silicon or a semiconductor material such as SiC having a bandgap larger than that of silicon.

The DC-AC power conversion circuit 102 includes a capacitor 104 and switching elements Q3 to Q8. Switching elements Q3 and Q4 are connected in series to U-phase, and switching elements Q5 and Q6 are connected in series to V-phase and switching elements. Q7 and Q8 are connected in series to form a W phase, respectively. Diodes D3 to D8 are connected in parallel to the switching elements Q3 to Q8 so that the flow directions are opposite to each other. Here, when the switching elements Q3 to Q8 are IGBTs, it is necessary to connect the diodes D3 to D8, but when the switching elements Q3 to Q8 are MOSFETs, the diodes D3 to D8 are not connected and the MOSFET is connected. Body diodes can be used. Further, the switching elements Q1 and Q2 of the DC-DC power conversion circuit 101 are used as IGBTs, and the switching elements Q3 to Q8 of the DC-AC power conversion circuit 102 are used as MOSFETs, or vice versa. The voltage drive type element of the IGBT may be mixedly mounted.

The DC-AC power conversion circuit 102 includes a capacitor 104 for smoothing the DC power output by the DC-DC power conversion circuit 101 and removing noise. The capacitor 104 is connected in parallel with the switching elements Q1 and Q2, and the switching elements Q3 and Q4 forming the U phase, the switching elements Q5 and Q6 forming the V phase, and the switching elements Q7 and Q8 forming the W phase. .. Further, the U-phase, V-phase, and W-phase switching elements Q3 to Q8 are controlled by, for example, PWM (Pulse Width Modulation) to convert the DC power of the capacitor 104 into AC power, thereby supplying AC power to the motor 5. .. Further, the voltage sensor 105 is arranged between the current collector 7 and the rail 2 (electrical ground) in order to detect the voltage of the overhead wire 1.

FIG. 3 shows the regenerative characteristics of the electric motor 5 when the DC-DC power conversion circuit 101 according to this embodiment operates. As a characteristic of the electric motor 5, a constant torque is output because the voltage applied to the electric motor 5 increases according to the speed in the low speed region of the vehicle 8. In the conventional drive device, since the DC voltage of the DC-AC power conversion circuit 102 is equal to the voltage of the overhead wire 1, a voltage higher than the voltage of the overhead wire 1 cannot be applied to the motor 5.

In particular, when the speed of the vehicle 8 increases, the current of the electric motor 5 decreases as the counter electromotive force of the electric motor 5 increases. That is, when the voltage that can be output by the DC-AC power conversion circuit 102 reaches a plateau, the maximum torque that can be output by the electric motor 5 is reduced. If the current capacities of the electric motor 5 and the DC-AC power conversion circuit 102 are increased in order to increase the maximum torque of the electric motor 5, the electric motor 5 and the DC-AC power conversion circuit 102 become large.

Further, when the vehicle 8 brakes, an air brake and an electric brake are used in combination with respect to the required braking force. In particular, when braking is applied from a state in which the vehicle 8 is traveling at a high speed (for example, 100 km / h), the output torque is limited because the voltage that can be applied to the electric motor 5 has reached a plateau in the conventional drive device. Since the insufficient braking force is covered by the air brake, it is consumed as heat energy, which is an adverse effect of energy saving.

In order to avoid this, in the drive device of this embodiment, a DC-DC power conversion circuit 101 is mounted between the overhead wire 1 and the DC-AC power conversion circuit 102.

The operation of the DC-DC power conversion circuit 101 will be described. DC power is supplied from the overhead wire 1 via the reactor 103 in the operation mode in which the power conversion device 6 powers to accelerate the vehicle 8. At this time, if the switching element Q1 is in the off state and the switching element Q2 is in the on state, electric power is stored in the reactor 103. Next, when the switching element Q2 is turned off, the electric power stored in the reactor 103 is supplied to the capacitor 104 via the diode D1. At this time, the switching element Q1 may be in the ON state and synchronously rectified.

That is, the power supplied by the DC-DC power conversion circuit 101 to the capacitor 104 is the sum of the power stored in the overhead wire 1 and the reactor 103. The electric power stored in the reactor 103 is due to the on-duty of the switching elements Q1 and Q2. For example, if the voltage of the overhead wire 1 is DC 1500V and the output voltage of the DC-DC power conversion circuit 101, that is, the voltage supplied to the capacitor 104 is DC 1800V, the on-duty of the switching element Q2 is 0.17 (= 1-). 1500/1800). On the other hand, the on-duty of the diode D1 (switching element Q1 at the time of synchronous rectification) is 0.83 (= 1-0.17).

On the other hand, when the power conversion device 6 regenerates because the vehicle 8 decelerates, the electric motor 5 becomes an AC voltage source and the electric power is regenerated to the overhead wire 1. At this time, the DC-AC power conversion circuit 102 converts the AC voltage of the electric motor 5 into a DC voltage by rectifying it, and stores the power in the capacitor 104. At this time, the voltage supplied to the capacitor 104 is, for example, 1800 V DC.

The DC-DC power conversion circuit 101 performs a step-down operation in order to change the voltage of the capacitor 104, for example, 1800 V, to 1500 V of the overhead wire 1. When the switching element Q1 is in the on state and the switching element Q2 is in the off state, electric power is regenerated to the overhead wire 1 via the reactor 103. Next, when the switching element Q1 is turned off, the current flowing through the reactor 103 tries to be constant, so that power is regenerated to the overhead wire 1 via the diode D2. At this time, the switching element Q2 is in the ON state and may be synchronously rectified.

The electric power regenerated by the DC-DC power conversion circuit 101 on the overhead wire 1 is the electric power stored in the reactor 103. The electric power stored in the reactor 103 is due to the on-duty of the switching elements Q1 and Q2. For example, if the voltage of the capacitor 104 is DC 1800V and the output voltage of the DC-DC power conversion circuit 101, that is, the voltage supplied to the overhead wire 1 is DC 1500V, the on-duty of the switching element Q1 is 0.83 (= 1500 /). 1800). On the other hand, the on-duty of the diode D2 (switching element Q2 at the time of synchronous rectification) is 0.17 (= 1-0.83).

By mounting the DC-DC power conversion circuit 101, a voltage higher than the voltage of the overhead wire 1 can be applied to the motor 5 to the motor 5. This is the same at the time of regeneration, and since the electric motor 5 can apply a voltage higher than the voltage of the overhead wire 1, the electric brake can be strengthened when the vehicle 8 is traveling at high speed.

For example, in the conventional drive device, the speed of the vehicle 8 at which the voltage applied to the electric motor 5 is maximum is 50 km / h, whereas the voltage is maximum by installing the DC-DC power conversion circuit 101. The speed of the vehicle 8 becomes 60 km / h. That is, since the area where the total electric brake can be applied increases by 10 km / h, it is not necessary to use the air brake in the area, and the regenerative power can be recovered to the maximum.

FIG. 4 shows the operation flow of the DC-DC power conversion circuit 101 according to this embodiment. When the vehicle 8 starts the braking operation, the driver operates the brake handle. Based on the notch information of the brake handle, the braking force required for the vehicle 8 to stop at the target position is calculated. As described above, since the electric brake that generates regenerative power is effective for energy saving, the command of the electric braking force is output with priority.

Next, the command value of the output torque required for the electric motor 5 is calculated based on the command of the electric braking force. If the motor output torque command value exceeds the maximum torque (stop torque) that the motor can output, it is necessary to use an air brake, which is an adverse effect on energy saving.

On the other hand, when returning the regenerative power to the overhead wire 1, when there is no vehicle that consumes the regenerative power around the vehicle applying the electric brake (light load regeneration), the voltage of the overhead wire 1 rises due to the regenerative current. To go. Since the upper limit of the voltage of the overhead wire 1 is predetermined, for example, 1830V, it is a problem that the state of light load regeneration increases when the DC-DC power conversion circuit 101 operates and the electric brake of the motor 5 is strengthened. It becomes.

Therefore, as the operation flow of the DC-DC power conversion circuit 101, the voltage of the overhead wire 1 is detected by using the voltage sensor 105 after the output torque command value of the electric motor 5 is output, and is compared with the overhead wire voltage upper limit value. At this time, if the upper limit of the overhead wire voltage is exceeded, the light load regeneration state occurs, so that the consumption destination does not exist even if the power regeneration occurs. Therefore, the electric braking force is fed back, the air braking force command is output from the difference from the required braking force, and the air brake is started.

On the other hand, when the voltage of the overhead wire 1 is equal to or less than the upper limit value of the overhead wire voltage, there are vehicles that consume regenerative power, so that it is effective to use an electric brake for energy saving. At this time, if the output torque command value of the electric motor 5 is equal to or less than the stall torque, all electric braking is possible even if the DC-DC power conversion circuit 101 does not operate.

On the other hand, when the output torque command value of the electric motor 5 exceeds the stall torque, all electric braking is possible by improving the output torque of the electric motor 5 in the high speed range by the DC-DC power conversion circuit. At this time, if the output voltage of the DC-DC power conversion circuit 101 exceeds the ratings of the switching elements Q1 to Q8, the power conversion device 6 fails. Therefore, for example, when the voltage rating of the switching elements Q1 to Q8 is 3300V, the output voltage of the DC-DC power conversion circuit 101 needs to be 2000V or less, for example.

According to the operation flow of the DC-DC power conversion circuit 101 according to this embodiment, the DC-DC-DC is obtained by comparing the output torque command value of the electric motor 5 at the time of braking with the stop torque while constantly monitoring the voltage of the overhead wire 1. The operation of the DC power conversion circuit 101 can be suppressed to the minimum necessary, leading to energy saving.

Further, for example, when one vehicle is traveling at a speed of 70 km / h and there is no vehicle that consumes regenerative power in the surroundings, it is not necessary to operate the DC-DC power conversion circuit 101. However, when the vehicle decelerates to 60 km / h after that and a vehicle that consumes regenerative power appears in the surroundings, operating the DC-DC power conversion circuit 101 to increase the electric braking force leads to energy saving. .. That is, according to this embodiment, not only when the vehicle travels at the maximum speed and the voltage applied to the electric motor 5 is maximized, but also DC-DC according to the voltage of the overhead wire 1 and the torque of the electric motor 5 required for braking. It is effective to operate the DC power conversion circuit 101.

FIG. 5 is a timing chart when the DC-DC power conversion circuit 101 according to the present embodiment operates, and shows the calculation result of the regenerated power with and without the operation of the DC-DC power conversion circuit 101. FIG. 5 shows a case where the vehicle is braking from a state of coasting at a high speed. At this time, if the DC-DC power conversion circuit 101 is not operating, the electric motor output torque is low at the timing when the brake is started, so that the air brake is frequently used. That is, sufficient regenerative power cannot be obtained and it cannot contribute to energy saving.

On the other hand, the output torque of the electric motor is increased by operating the DC-DC power conversion circuit 101 at the timing of starting to apply the brake. As a result, the use of the air brake can be suppressed and the regenerative power can be increased.

FIG. 6 is an example of a breakdown of the power consumption when the DC-DC power conversion circuit 101 according to this embodiment operates. By applying the control flow of the DC-DC power conversion circuit 101 of this embodiment, the power consumption by the air brake can be suppressed and the regenerated power amount can be increased. As a result, the amount of electric power consumed when one vehicle travels 1 km (vehicle basic unit [kWh / km / Car] can be reduced, which greatly contributes to energy saving.

In this embodiment, power is interchanged by a plurality of vehicles. Hereinafter, the differences from the first embodiment will be mainly described.

FIG. 7 is a schematic view of power interchange in a plurality of vehicles according to this embodiment. In the first embodiment, the DC-DC power conversion circuit 101 was controlled according to the voltage of the overhead wire 1 and the torque of the electric motor 5 required for braking. On the other hand, in the present embodiment, the DC-DC power conversion is performed. As the control flow of the circuit 101, control is performed based not only on the voltage information of the overhead wire 1 but also on the traveling mode of another vehicle. Each vehicle is equipped with a vehicle information control device 9 that transmits and receives travel mode information such as power running and regeneration operation information, and the travel mode information is collected by the vehicle information calculation device 10. Here, the regenerative power can be maximized by the vehicle information arithmetic unit 10 controlling the DC-DC power conversion circuit 101 based on the power running and regenerative operation information of a plurality of vehicles.

For example, when one vehicle is regenerating, the vehicle information calculation device 10 detects that there is a vehicle that is trying to power out among the vehicles connected to the same overhead line. By transmitting a signal to the vehicle information control device 9 based on this detected signal, if the electric motor output torque of the regenerative vehicle is insufficient, the DC-DC power conversion circuit 101 is operated to increase the number. Regenerative power can be used for power vehicles.

That is, according to this embodiment, the DC-DC power conversion circuit 101 can be controlled and the regenerative power can be maximized from the information on the traveling conditions of a plurality of vehicles and the electric motor output torques of the regenerative vehicles among them.

This embodiment is an implementation example of a power conversion device. Hereinafter, the differences from the first and second embodiments will be mainly described.

FIG. 8 is an implementation example of the power conversion device 6 according to this embodiment. Since the power conversion device 6 is equipped with a DC-DC power conversion circuit 101 in addition to the conventional DC-AC power conversion circuit 102, it is desirable to reduce the size in applications such as railways where the underfloor space is limited.

Therefore, the power conversion device 6 of this embodiment uses eight 1in1 modules in which the switching element Q1 and the diode D1 are enclosed in the same package. Further, by mounting the DC-DC power conversion circuit 101 and the DC-AC power conversion circuit 102 on the same cooler 106, the dead space can be eliminated, which contributes to miniaturization.

A 2in1 module in which the upper and lower arms of the power conversion device 6 (for example, the switching elements Q1 and Q2 and the diodes D1 and D2) are enclosed in the same package may be used, and the switching elements Q1 to Q8 and the diodes D1 to D8 are plural. The modules may be connected in parallel.

1 Overhead wire 2 Rail 3 Wheel 4 Cart 5 Electric power 6 Power conversion device 7 Current collector 8 Vehicle 9 Vehicle information control device 10 Vehicle information calculation device 100 DC-DC power conversion circuit operation flow 101 DC-DC power conversion circuit 102 DC- AC power conversion circuit 103 reactor 104 capacitor 105 voltage sensor 106 cooler Q1 to Q8 switching element D1 to D8 diode

Claims (9)

A first power conversion circuit that converts DC power supplied from a DC overhead wire to DC-DC power by a plurality of switching elements, and a DC-AC power conversion that converts the output power of the first power conversion circuit by a plurality of switching elements. In a power conversion device for railroad vehicles, which has a second power conversion circuit for driving an electric motor.
When the torque of the electric motor required for braking is higher than the predetermined torque and the voltage of the DC overhead wire is lower than the predetermined voltage, the input voltage of the second power conversion circuit is the DC overhead wire. A power converter for railroad vehicles, characterized in that the voltage is higher than the voltage of. In the power conversion device for railway vehicles according to claim 1.
A power conversion device for a railway vehicle, wherein the first power conversion circuit is controlled based on information on a traveling mode of another electric vehicle. In the power conversion device for railway vehicles according to claim 2.
A power conversion device for railway vehicles, wherein the traveling mode is power running or regeneration operation information. In the power conversion device for railway vehicles according to any one of claims 1 to 3.
A power conversion device for railroad vehicles, wherein the switching element is made of silicon or a semiconductor material having a band gap larger than that of silicon as a base material. In the power conversion device for railway vehicles according to any one of claims 1 to 4.
A power conversion device for railway vehicles, wherein the switching element is a voltage-driven element of a MOSFET or an IGBT. In the power conversion device for railway vehicles according to any one of claims 1 to 5.
A power conversion device for railroad vehicles, characterized in that the switching elements on the upper arm and the lower arm have a 2-in-1 configuration enclosed in the same package. In the power conversion device for railway vehicles according to any one of claims 1 to 6.
A power conversion device for a railway vehicle, characterized in that the plurality of switching elements of the first power conversion circuit have a 2in1 configuration enclosed in the same package. In the power conversion device for railway vehicles according to any one of claims 1 to 7.
A power conversion device for a railroad vehicle, wherein the first power conversion circuit and the second power conversion circuit are mounted on the same cooler. A railway vehicle equipped with the power conversion device for a railway vehicle according to any one of claims 1 to 8.

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