JP2005117819A - Power conversion device for electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power conversion device for an electric vehicle reducible in size even if the device is equipped with a converter device and inverter devices. <P>SOLUTION: The power conversion device for the electric vehicle comprises the converter device (3) of which the switching element is connected in a manner of single-phase bridging, and which converts a single-phase AC to a DC; first and second inverter devices (5a, 5b) of which each switching element is connected in a three-phase bridging, and each of which converts the DC converted by the converter device to a three-phase AC; a cooling medium circulation passage (11) in which the intermediate zone of a piping passage that circulates a cooling medium is divided into two branches, one branch (12) is thermally coupled to a U-phase switching element unit (3a) of the converter device and the first inverter device (5a), and the other branch (13) is thermally coupled to a V-phase switching element unit (3b) of the converter device and the second inverter device (5b); a pump (14) for circulating the cooling medium arranged at a main passage of the cooling medium circulation passage; and a heat exchanger (15) arranged at the main passage of the cooling medium circulation passage. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a power conversion device used for a railway vehicle, particularly an electric vehicle, and more particularly to cooling of the power conversion device.

  A power conversion device including a converter device and an inverter device is used for an electric vehicle traveling in an AC feeding section. FIG. 5 is a circuit diagram showing the configuration of this type of power converter. In the figure, the alternating current collected from the pantograph 1 is stepped down by the main transformer 2 and input to the alternating current side of the converter device 3 including the U-phase switching element unit 3a and the V-phase switching element unit 3b. The direct current output from the direct current side of the converter device 3 is input to the direct current side of the inverter device 5a and the inverter device 5b via the filter capacitors 4a and 4b connected in parallel. The inverter devices 5a and 5b output three-phase alternating currents of variable voltage and variable frequency that are PWM modulated by outputting pulses having three levels of positive, negative, and neutral respectively. The rotation of the induction main motors 6a, 6b, 6c, 6d for driving the electric vehicle is controlled by the three-phase alternating current, and the electric vehicle is powered. On the other hand, when the induction type main motors 6a, 6b, 6c, 6d are regenerated as a generator, energy is regenerated in the pantograph 1 as opposed to the above power running.

  Each of the converter device 3 and the inverter devices 5a and 5b described above has a configuration in which module type self-extinguishing switching elements such as IGBT (Insulated Gate Bipolar Transistor) and GTO (Gate Turn Off thyristor) are bridge-connected. . These switching elements are all heat generating elements for the cooling system, and if they are mounted closely, they become thermally severe. On the other hand, the layout is also an important factor in consideration of maintenance, and cannot always be convenient for cooling.

  In response to these demands, circulating liquid cooling is performed by passing cooling liquid through a heat receiving plate to which a module type semiconductor switching element constituting the power conversion device is attached and circulating the cooling liquid between the air-liquid heat exchanger. While adopting the system, as a refrigerant to be used, for example, water or an aqueous solution containing an ethylene glycol component that suppresses freezing at low temperatures is disclosed (for example, see Patent Document 1).

  On the other hand, an electric vehicle traveling in a DC feeding section does not require a transformer or a converter device used when traveling in an AC feeding section. However, since an inverter device composed of IGBTs and GTOs tends to increase in size, it is desired to devise the configuration of the device and downsize the electric vehicle inverter device as a whole.

In order to enable this miniaturization and to improve maintainability even if it is installed in a narrow place such as under the floor of an electric vehicle, the switching-connected module of bridge connection is divided for each phase. The same heat receiving plate having heat conductivity is attached to one surface, and one end of the heat pipe is thermally coupled to the other surface of the heat receiving plate, and a heat radiating portion is formed at the other end, and water is used as a working fluid. An inverter device for connecting a conventional cooler is disclosed (for example, see Patent Document 2).
JP-A-9-219904 JP-A-11-8982

  Of the two power converters described above, a power converter for an electric vehicle traveling in an AC feeding section, that is, a power converter having a converter device and an inverter device, is equivalent to one phase (S phase, T phase, U Since the four heat receiving plates with the elements to be cooled (phase, V phase, W phase) attached on both sides are arranged in the track direction and these are integrally housed in a single casing, There is a problem that the apparatus becomes large in order to dispose in a limited space under the floor.

  On the other hand, a power conversion device consisting only of an inverter device that runs in a DC feeding section divides a semiconductor switch module for each phase and attaches it to one surface of the same heat receiving plate, and thermally connects a cooler to the other surface. As a result, the amount of heat load on the cooler can be averaged, thereby reducing the size of the cooler and the size of the entire apparatus. However, there is a problem that it is difficult to apply to a power conversion device including a converter device, such as an electric vehicle traveling in an AC feeder section.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electric vehicle power converter that can be reduced in size even when a converter device and an inverter device are provided. .

  Another object of the present invention is to provide a power converter for an electric vehicle that improves reliability and is advantageous in terms of economy.

The invention according to claim 1
A converter device in which a switching element is connected in a single-phase bridge, and converts a single-phase alternating current into a direct current;
A first and a second inverter device, each of which has a switching element connected in a three-phase bridge and converts the direct current converted by the converter device into a three-phase alternating current;
A section in the middle of the piping path for circulating the refrigerant is branched into two, one branch is thermally coupled to the U-phase switching element unit of the converter device and the first inverter device, and the other branch is the converter device. A refrigerant circuit thermally coupled to the V-phase switching element unit and the second inverter device,
A pump for circulating the refrigerant provided in the main path of the refrigerant circulation path;
A heat exchanger provided in the main path of the refrigerant circuit;
It is the electric power converter for electric vehicles provided with.

  According to a second aspect of the present invention, in the electric vehicle power converter according to the first aspect, the first and second converter devices have the same capacity, and the branch portions have substantially the same cooling performance.

  According to a third aspect of the present invention, in the electric vehicle power converter according to the first or second aspect, the suspension is suspended so as to leave a space in the wind tunnel under the floor of the vehicle, and a part thereof forms an airtight portion. A partitioned housing is provided, the converter device and the inverter device are housed in an airtight portion of the housing, and the pump is housed in a non-airtight portion.

  According to a fourth aspect of the present invention, in the power conversion device for an electric vehicle according to any one of the first to third aspects, the heat exchanger is installed at a part that is separated from the housing and naturally cooled by the traveling wind. ing.

  According to a fifth aspect of the invention, in the electric vehicle power converter according to the third or fourth aspect of the invention, the electric vehicle power converter is installed at a portion where the temperature is predicted to be highest among the hermetic portions in which the converter device and the inverter device are housed. And a flow rate control unit that controls the flow rate of the pump so that the detection value of the temperature sensor does not exceed a predetermined value.

  According to a sixth aspect of the present invention, in the electric vehicle power converter according to the sixth aspect of the present invention, the electric vehicle power converter includes a current sensor that detects a current of the main motor driven by the inverter, and the flow rate control unit is responsive to the detected current of the current sensor. The flow rate of the pump is controlled so that a predetermined refrigerant is supplied.

  The invention according to claim 7 is the electric vehicle power converter according to claim 5 or 6, further comprising means for detecting running and stopping of the electric vehicle, and the flow rate control unit is configured to detect whether the electric vehicle is running or stopped. Change the flow rate with.

  According to the present invention, the refrigerant is forcibly circulated by the refrigerant circulation path in which the middle section of the piping path for circulating the refrigerant is branched into two, and one branch portion is the U-phase switching element unit of the converter device, Since it is thermally coupled to the first inverter device and the other branch is thermally coupled to the V-phase switching element unit of the converter device and the second inverter device, even when the converter device and the inverter device are provided Provided is an electric vehicle power converter that can be reduced in size.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, the present invention will be described in detail based on preferred embodiments shown in the drawings. FIG. 1 is a circuit diagram showing the configuration of a main circuit of a power converter to which the present invention is applied. In FIG. 1, the same elements as those in FIG. To do. In this case, the U-phase switching element unit 3a and the V-phase switching element unit 3b constituting the converter device 3 have the same circuit configuration. The inverter devices 5a and 5b have the same circuit configuration. Therefore, in the present embodiment, the U-phase switching element unit 3a and the inverter device 5a are used as one unit to be cooled, and the V-phase switching element unit 3b and the inverter device 5b are used as another unit to be cooled, thereby cooling both the cooling structures. Are made the same, and these are forced circulation water cooling systems to reduce the size of the apparatus.

  FIG. 2 is a block diagram showing a schematic configuration of an embodiment of the power conversion device according to the present invention. In the figure, the U-phase switching element unit 3a and the inverter device 5a are one unit to be cooled, and the V-phase switching element unit 3b and the inverter device 5b are another unit to be cooled. Are collectively stored in a housing described later. A refrigerant circulation path 11 is provided to cool the power unit portion 7. The refrigerant circulation path 11 has branches 12 and 13 in the middle of the piping path. Of these, the branch 12 is coupled to the U-phase switching element unit 3a and the inverter device 5a so that heat can be transferred. Is coupled to the V-phase switching element unit 3b and the inverter device 5b so that heat can be transferred. In addition, for example, a pump 14 that circulates an aqueous solution containing an ethylene glycol component is provided as a refrigerant in the main path of the refrigerant circulation path 11, and the main unit led out to the outside of the casing in which the power unit unit 7 is housed. The path is provided with a heat exchanger 15 that exchanges heat with the traveling wind using cooling fins.

  As the pump 14, a pump with variable capacity control is used, and a flow rate control unit 20 for controlling the rotation speed is provided. The flow rate control unit 20 includes a flow rate sensor 21 provided in the main path of the refrigerant circulation path 11, a temperature sensor 22 installed in a portion where the temperature is predicted to be highest in the housing in which the power unit unit 7 is housed, and an induction The rotational speed of the pump 14 is controlled based on each output signal of the CT 23 that detects the current of the main motor 6a.

  FIG. 3 is a bottom view particularly showing an attachment state of elements related to the present embodiment in order to explain the configuration of the bottom portion of the electric vehicle on which the above-described power conversion device is mounted. Here, the electric vehicle 30 includes a carriage 31 at one end in the traveling direction, and a carriage 32 at the other end. The electric power converter 8 is attached to an intermediate portion, and is separated from the electric power converter 8. The heat exchanger 15 and the main transformer 2 are attached to the main body. FIG. 4A is a side view of a part of the electric vehicle showing the mounting state of the elements related to this embodiment, and the power conversion device 8 is suspended so as to leave a space for the wind tunnel 9 at the bottom of the electric vehicle 30. The heat exchanger 15 and the main transformer 2 are attached to the side of the housing. FIG. 4B is a cross-sectional view for illustrating a mounting state of elements constituting the power conversion device 8. The power conversion device 8 includes a casing 80 partitioned into a power unit storage portion 81 and an airtight portion 82, the power unit portion 7 described above is stored in the power unit storage portion 81, and the pump 14 and the flow sensor 21 are stored in the airtight portion 82. Has been. The power unit storage unit 81 stores a probe, a resistor, and the like, and the airtight unit 82 stores a charging unit, an overvoltage suppression thyristor unit, and the like. However, these are not directly related to the present invention and are not shown. doing.

  The operation of the present embodiment configured as described above will be described below with a focus on portions that differ from the conventional apparatus. The U-phase switching element unit 3a constituting the converter device 3 and the inverter device 5a are thermally coupled to the branching section 12 as a set of heating elements serving as a unit to be cooled, and the converter device is used as another set of heating elements. 3 and the inverter device 5b are thermally coupled to the branching section 13. Since the power capacities of these heating elements are equal to each other and the same current flows in principle, the amount of heat generated by both of them is also substantially equal. Correspondingly, the diameters of the pipes of the branch parts 12 and 13, the total length of the coupling part, and the bending shape are made the same to give substantially the same cooling performance. Therefore, when the aqueous solution containing the ethylene glycol component is circulated in the refrigerant circulation path 11 by the pump 14, the heat generated by the two sets of switching elements is absorbed by the aqueous solution in the branch portions 12 and 13, and then in the heat exchanger 15. Then, heat is exchanged with the traveling wind to dissipate heat, and the switching elements constituting the converter device 3 and the inverter devices 5a and 5b are cooled, and the resistance values of these switching elements are kept substantially equal.

  Here, the flow rate control unit 20 executes the control of the following items a to c.

a. Of the non-hermetic part in which the power unit 7 is housed, the flow rate of the pump is maintained at a steady value as long as the detection value of the temperature sensor 22 installed in the part where the temperature is predicted to be highest does not exceed a predetermined threshold. To do. Each time the detected value of the temperature sensor 22 exceeds the threshold value, the speed of the pump 14 is increased so that the flow rate detected by the flow rate sensor 21 increases by a predetermined value. On the contrary, every time the detected value of the temperature sensor 22 falls below the threshold value, the operation of decreasing the speed of the pump 14 is repeated so that the flow rate detected by the flow rate sensor 21 decreases by a predetermined value.

b. The threshold value of the a term is changed continuously or stepwise according to the detected value of CT 23 provided to detect the currents of the induction main motors 6a, 6b, 6c, 6d. As a result, the flow rate of the pump 14 is controlled such that a predetermined refrigerant is supplied according to the detected current of the CT 23.

c. The control of the above items a and b is mainly control during running of the electric vehicle, but the current of the converter device 3 and the inverter devices 5a and 5b becomes substantially zero when the electric vehicle is stopped. It is necessary to operate by changing the steady value and threshold value of the pump flow rate. Therefore, the flow control unit 20 determines whether the electric vehicle is running or stopped based on the current detection signal of the CT 23, and operates while changing the steady value and the threshold value during the stop.

  By executing the above control, the temperature of the switching element, which is a heating element, can be suppressed to a preset value.

  Thus, according to the present embodiment, the converter device and the switching device unit of the inverter device are combined to form two sets of heating elements (or units to be cooled) so that the calorific values are substantially the same, and the refrigerant is forcibly circulated. The size of the apparatus can be reduced by the configuration in which the refrigerant circulation path is thermally coupled to each branch path. In addition, since control is performed such that the temperature of the switching element does not exceed the threshold according to the temperature of the part in which the power unit unit 7 is stored, the current and operation of the motor, and the stop state, the reliability is improved, It is also advantageous in terms of economy.

  Moreover, according to said embodiment, since the main transformer 2, the heat exchanger 15, and the power converter device 8 are mutually spaced apart, the influence of the thermal radiation from the main transformer 2 with respect to the heat exchanger 15 is carried out. Is avoided, and the cooling efficiency of the heat exchanger 15 is increased.

  Furthermore, according to the above-described embodiment, since the cooling system is a set of one converter device and two inverter devices, it is effective for the carriage and the individual system.

  In the above-described embodiment, the steady flow rate of the refrigerant and the flow rate increase / decrease threshold are changed according to the temperature of the part in which the power unit unit 7 is stored, the current of the motor, the operation, and the stop state, but the power unit unit 7 is stored. Even if the flow rate is controlled only by the temperature of the part, or the flow rate is controlled according to the temperature of the part in which the power unit 7 is accommodated and the current of the electric motor, the same effect as described above can be obtained.

The circuit diagram which shows the structure of the main circuit of the power converter device to which this invention is applied. The block diagram which shows schematic structure of one Embodiment of the power converter device for vehicles which concerns on this invention. The bottom view of the electric vehicle with which the power converter device shown in FIG. 2 was mounted | worn. The side view and sectional drawing of the electric vehicle which showed the attachment state of the element relevant to embodiment shown in FIG. The circuit diagram which shows the structure of the conventional electric power converter for electric vehicles.

Explanation of symbols

2 Main transformer 3 Converter device 3a U-phase switching element unit 3b V-phase switching element unit 5a, 5b Inverter devices 6a, 6b, 6c, 6d Induction main motor 7 Power unit 8 Power converter 11 Refrigerant circulation path 12, 13 Branch Unit 14 Pump 15 Heat exchanger 20 Flow rate control unit 21 Flow rate sensor 22 Temperature sensor 23 CT
30 Electric cars 31, 32

Claims (7)

A converter device in which a switching element is connected in a single-phase bridge, and converts a single-phase alternating current into a direct current;
A first and a second inverter device each having a switching element connected in a three-phase bridge and converting the direct current converted by the converter device into a three-phase alternating current;
A section in the middle of the piping path for circulating the refrigerant is branched into two, one branch is thermally coupled to the U-phase switching element unit of the converter device and the first inverter device, and the other branch is A refrigerant circuit thermally coupled to the V-phase switching element unit of the converter device and the second inverter device;
A refrigerant circulation pump provided in the main path of the refrigerant circulation path;
A heat exchanger provided in the main path of the refrigerant circuit;
An electric vehicle power conversion device comprising:   2. The electric power converter for an electric vehicle according to claim 1, wherein the first and second converter devices have the same capacity, and the branch portion has substantially the same cooling performance.   A casing suspended under the floor of the vehicle so as to leave a space in the wind tunnel, a part of which is partitioned to form an airtight portion, and the converter device and the inverter device are accommodated in the airtight portion of the housing. The electric power converter for an electric vehicle according to claim 1, wherein the pump is housed in the non-hermetic portion.   The electric power converter for an electric vehicle according to any one of claims 1 to 3, wherein the heat exchanger is installed in a portion that is separated from the housing and is naturally cooled by traveling wind.   Of the airtight part in which the converter device and the inverter device are housed, a temperature sensor installed at a portion where the temperature is predicted to be highest, and a flow rate of the pump so that a detection value of the temperature sensor does not exceed a predetermined value. The electric power converter for electric vehicles according to claim 3 or 4 provided with the flow control part which controls.   A current sensor for detecting a current of a main motor driven by the inverter is provided, and the flow rate control unit controls a flow rate of the pump so that a predetermined refrigerant is supplied according to a current detected by the current sensor. The electric power converter for electric vehicles according to claim 6.   The electric vehicle power conversion device according to claim 5 or 6, further comprising means for detecting running and stopping of the electric vehicle, wherein the flow rate control unit changes the flow rate during and when the electric vehicle is running.

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