Power converter

Abstract

To suppress fuel consumption while coping with steep fluctuation in load power.SOLUTION: A power converter (1) includes power generation systems (13, 15), is connected to an electric motor (21) via a switch (3), and includes a control unit (12) that outputs a command to increase output to the power generation systems (13, 15) in advance before load fluctuation. The control unit (12) receives control information including information of a control target device (23) connected to the electric motor (21) and information indicating a condition under which the switch (3) is turned on from a load control unit (22) which controls the switch (3), and outputs a command when it is determined from the control information that the switch (3) is likely to be turned on within a predetermined time.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a power conversion device for railway vehicles.

Background Art

[0002] In recent years, for the improvement of maintainability and the reduction of carbon dioxide emissions, the electrification of railway vehicles powered by internal combustion engines, that is, the diesel-electric system, has been progressing.

[0003] In the diesel-electric system, the conventional transmission mechanism specific to diesel locomotives has been electrified due to the progress of power electronics technology, and the development of engine control methods for energy saving has also been progressing (see, for example, Non-Patent Document 1).

[0004] On the other hand, in order to cope with the increased load of the air conditioner and improve the reliability of the vehicle's braking system, the proportion of induction motors used for the control of the air compressor in the vehicle has increased, and a control method of directly connecting a three-phase AC power supply to the induction motor has become common for the further simplification of the control circuit.

[0005] Also, Patent Document 1 discloses a power conversion system that can achieve both the control of the engine rotation speed and the control of the intermediate circuit voltage with a simple configuration.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Non-Patent Documents

[0007]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] As shown in Patent Document 1, as a characteristic of a diesel engine, in order to improve fuel efficiency, the engine speed is low and controlled aiming at the limit line of the output characteristics, so there is no control margin for steep load fluctuations.

[0009] In order to prevent engine stall when the air conditioner or air compressor suddenly operates even when the vehicle is stopped, it is necessary to always control at a relatively high engine speed. As a result, there is a problem that fuel consumption increases.

[0010] In view of such circumstances, an object of the present invention made is to provide a power conversion device capable of suppressing fuel consumption while coping with steep fluctuations in load power.

Means for Solving the Problems

[0011] The gist of the present invention for solving the above problems is as follows.

[0012] (1) A power conversion device that includes a power generation system and is connected to an electric motor via a switch, wherein a control target device is connected to the electric motor, and includes a control unit that outputs a command to increase the output of the power generation system in advance before load fluctuations. The control unit receives control information including information on the control target device and information indicating a condition for turning on the switch from a load control unit that controls the switch, and when it is determined from the control information that the switch may be turned on within a certain time, the control unit outputs the command. Power conversion device.

[0013] (2) A power conversion device that includes a power generation system and is connected to an electric motor via a switch, wherein a control target device is connected to the electric motor, and the power conversion device includes a control unit that outputs a command to increase the output of the power generation system in advance before a load fluctuation occurs. When the control unit receives information indicating that the switch may be turned on within a certain period of time from a load control unit that controls the switch, the control unit outputs the command.

[0014] (3) The control target device is an air conditioner, and the control unit outputs the command when a difference between a set temperature and a current temperature of the air conditioner is equal to or greater than a threshold value. The power conversion device according to (1) or (2).

[0015] (4) The control target device is an air compressor including an air tank, and the control unit outputs the command when a difference between a set pressure of the air compressor and a pressure of the air tank is equal to or greater than a threshold value. The power conversion device according to (1) or (2).

Advantages of the Invention

[0016] According to the present invention, it is possible to predict the occurrence of a rapid load fluctuation and increase the responsiveness of the power supply side only at that time, and it is possible to suppress unnecessary fuel consumption while coping with a steep fluctuation in load power.

Brief Description of the Drawings

[0017]

Figure 1

Modes for Carrying Out the Invention

[0018] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0019] FIG. 1 is a diagram showing a configuration example of a power conversion device according to an embodiment of the present invention. The power conversion device 1 shown in FIG. 1 includes a command unit 11, a control unit 12, a power generation system (converter 13 and power source 15), and an inverter 14.

[0020] The load system 2 includes a motor 21, a device to be controlled 23, and a load control unit 22 for controlling the device to be controlled 23. The load system 2 is a system that directly drives the motor 21 without power control and announces the operation of the motor 21. The power conversion device 1 is connected to the motor 21 via a switch 3.

[0021] The command unit 11 outputs the operation command input from the master controller (main controller) to the control unit 12.

[0022] Based on the power output command input from the control unit 12, the power supply 15 outputs power to the converter 13. The power supply 15 is assumed to be a power supply with relatively low followability to power fluctuations, such as an internal combustion engine or a fuel cell. When the power supply 15 is composed of an internal combustion engine and a generator, the internal combustion engine generates mechanical energy (kinetic energy), and the generator converts the mechanical energy generated by the internal combustion engine into AC power. When the power supply 15 is a fuel cell, the fuel cell generates DC power through the electrochemical reaction of hydrogen and oxygen.

[0023] Based on the power conversion command input from the control unit 12, the converter 13 converts the power input from the power supply 15 into a predetermined DC power and outputs it to the inverter 14.

[0024] The inverter 14 converts the DC power input from the converter 13 into AC power and generates the power supply for auxiliary equipment.

[0025] The motor 21 is a load of the inverter 14, and an induction motor is assumed. The motor 21 has load fluctuations faster than the response speed of the power generation system.

[0026] The device to be controlled 23 is, for example, a braking system that uses an air compressor driven by the motor 21 and an external air compressor and includes an air tank used in the air circuit of a vehicle. Alternatively, the device to be controlled 23 is an air conditioning device that includes a refrigerant compressor driven by the motor 21, and the air conditioning device controls the temperature in the passenger compartment.

[0027] Switch 3 controls the device 23 to be controlled by means of an on / off operation.

[0028] The load control unit 22 controls the electric motor 21 by controlling the switch 3. When the switch 3 is turned on, there is an instantaneous power fluctuation with respect to the inverter 14, and as a result, there is also an instantaneous power fluctuation with respect to the converter 13 and the power supply 15, which becomes an overload power that the control unit 12 does not grasp.

[0029] The load control unit 22 transmits control information to the control unit 12 of the power conversion device 1. The control information is information including information (control target information) of the device 23 to be controlled connected to the load control unit 22, information (switch operation condition) indicating the condition for the switch 3 to turn on, and the operation state of the switch 3. The switch operation condition is determined according to the state of the device 23 to be controlled.

[0030] The control unit 12 always adds the rated power to the output power according to the operation command received from the command unit 11 and the power borne by the inverter 14, and outputs a power output command to the power supply 15 and outputs a power conversion command to the converter 13.

[0031] The control unit 12 estimates the load fluctuation in advance and outputs a command to increase the output to the power generation system (converter 13 and power supply 15) in advance before the load fluctuation. That is, when the control unit 12 receives the control information from the load control unit 22, it determines whether there is a possibility that the switch 3 will turn on within a certain time from the control target information and the switch operation condition. And when the control unit 12 determines that there is a possibility that the switch 3 will turn on within a certain time, it outputs a command to increase the output to the power generation system, and the converter 13 and the power supply 15 output the power as commanded. When the power supply 15 is composed of an internal combustion engine and a generator, the engine speed increases, and when the power supply 15 is a fuel cell, the hydrogen supply amount increases.

[0032] When the device to be controlled 23 is an air conditioner, the control unit 12 determines from the control information that if the difference between the set temperature and the current temperature of the air conditioner is equal to or greater than the threshold value, switch 3 may turn on within a certain period of time, and outputs a command to increase the output to the power generation system.

[0033] When the device to be controlled 23 is an air compressor, the control unit 12 determines from the control information that if the difference between the set pressure of the air compressor and the pressure of the air tank is equal to or greater than the threshold value, switch 3 may turn on within a certain period of time, and outputs a command to increase the output to the power generation system.

[0034] After that, the load control unit 22 turns on switch 3, an inrush current flows through the motor 21, and then it enters a steady state.

[0035] Since the steady state is reached after a certain period of time has elapsed since switch 3 was turned on, the control unit 12 stops the command to increase the output based on the operating state of switch 3 received from the load control unit 22 or the operating state of the inverter 14, and returns to the normal operating state.

[0036] <Modification Example> In the above-described embodiment, the load control unit 22 transmits the control information to the control unit 12, and the control unit 12 determines from the control information whether switch 3 may turn on within a certain period of time. On the other hand, in the modification example, this determination is made in the load control unit 22, and when it is determined that switch 3 may turn on within a certain period of time, information indicating that switch 3 may turn on within a certain period of time is transmitted to the control unit 12.

[0037] When the device to be controlled 23 is an air conditioner, the load control unit 22 transmits information indicating that switch 3 may turn on within a certain period of time to the control unit 12 when the difference between the set temperature and the current temperature of the air conditioner is equal to or greater than the threshold value. Then, when the control unit 12 receives this information from the load control unit 22, it outputs a command to increase the output to the power generation system.

[0038] When the device to be controlled 23 is an air compressor, the load control unit 22 transmits information indicating that switch 3 may turn on within a certain period of time to the control unit 12 when the difference between the set pressure of the air compressor and the pressure of the air tank is equal to or greater than a threshold value. Then, when the control unit 12 receives the information from the load control unit 22, it outputs a command to increase the output of the power generation system.

[0039] As described above, the power conversion device 1 predicts the occurrence of a sudden change in the load and performs operations to increase the engine speed and hydrogen supply amount only when necessary, thereby increasing the response on the power supply side. Therefore, the power supply 15 can respond to the instantaneous power change of the load with a minimum power output. That is, it is possible to control to withstand the instantaneous power change while operating the power supply 15 at a minimum and keeping the fuel consumption suppressed as much as possible.

[0040] Although the above-described embodiments have been described as representative examples, it is obvious to those skilled in the art that many changes and substitutions can be made within the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications or changes are possible without departing from the scope of the claims. For example, it is possible to integrate a plurality of constituent blocks described in the configuration diagrams of the embodiments or divide one constituent block.

Description of Reference Numerals

[0041] 1 Power conversion device 2 Load system 3 Switch 11 Command unit 12 Control unit 13 Converter 14 Inverter 15 Power supply 21 Electric motor 22 Load control unit 23 Device to be controlled

Claims

1. A power conversion device that includes a power generation system and is connected to an electric motor via a switch, wherein a control target device is connected to the electric motor, and includes a control unit that outputs a command to increase the output of the power generation system in advance before load fluctuation, wherein the control unit receives control information including information on the control target device and information indicating a condition under which the switch turns on from a load control unit that controls the switch, and outputs the command when it is determined from the control information that the switch may turn on within a certain period of time. Power conversion device.

2. A power conversion device that includes a power generation system and is connected to an electric motor via a switch, wherein a control target device is connected to the electric motor, and includes a control unit that outputs a command to increase the output of the power generation system in advance before load fluctuation, wherein the control unit outputs the command when receiving information indicating that the switch may turn on within a certain period of time from a load control unit that controls the switch. Power conversion device.

3. The control target device is an air conditioner, The power conversion device according to claim 1 or 2, wherein the control unit outputs the command when a difference between a set temperature and a current temperature of the air conditioner is equal to or greater than a threshold value.

4. The control target device is an air compressor including an air tank, The power conversion device according to claim 1 or 2, wherein the control unit outputs the command when a difference between a set pressure of the air compressor and a pressure of the air tank is equal to or greater than a threshold value.

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