JP2011004566A - Auxiliary power supply apparatus for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an auxiliary power supply apparatus for an electric vehicle with high energy utilization efficiency without enlarging the apparatus or increasing complexity.SOLUTION: A battery 43 is connected to a DC input side of an inverter 42, that is, a DC input side of a converter 41, and charged by a DC power input into the inverter 42 from the converter 41 with a lower voltage than a DC power supplied from a converter 32 to a main motor 31. Accordingly, charging or discharging of the battery 43 is directly controlled by a DC power output from the converter 41 without use of a dedicated DC/DC converter.

Description

  The present invention relates to an electric vehicle auxiliary power supply device.

  2. Description of the Related Art Conventionally, an electric vehicle auxiliary power supply device is known that includes power storage means for charging electric power from an overhead line and regenerative electric power from a main motor, and supplying the charged electric power to the main motor and various auxiliary devices as necessary (for example, Patent Documents 1 and 2). In the case of an AC electric vehicle, for example, as shown in FIG. 3, the electric vehicle 100 collects AC power from an overhead wire 101 by a current collector 102. The electric vehicle 100 controls the power supplied to the main motor 106 by the converter 104 and the inverter 105 after the collected AC power is transformed by the transformer 103. A DC / DC converter 107 that varies the DC voltage is connected to the DC output side of the converter 104, and a power storage means 108 such as a lithium ion battery is connected to the output side of the DC / DC converter 107. The power storage means 108 has a relatively large charge capacity, and generally charges and discharges electric power for driving the main motor 106.

JP 2004-056934 A JP 2008-253084 A

  However, in the case of such a conventional electric vehicle 100, in order to charge and discharge the power storage means 108, a DC / DC converter 107 that varies the voltage of the DC power output from the converter 104 is required. For this reason, there is a problem that the number of elements and devices increases, leading to an increase in size and complexity of the device. On the other hand, in the case of the electric vehicle 100 that does not include the power storage means 108, it is caused by regeneration when power cannot be regenerated, for example, when a power failure occurs in the overhead line 101 or when it passes through a feeder section, so-called cross-intersection section. The electric power must be consumed as thermal energy or braked with a mechanical brake. As a result, there is a problem that energy is wasted.

  Therefore, the present invention is to provide an electric vehicle auxiliary power supply device with high energy use efficiency without causing an increase in size and complexity of the device.

  In order to solve the above problems, an electric vehicle auxiliary power supply apparatus of the present invention includes a transformer for stepping down AC power collected from an overhead line and supplying the same to a main motor, and AC power transformed by the transformer as DC power. A converter to be converted, an inverter connected to the DC power output side of the converter, converting the input DC power into AC power and outputting it to an auxiliary device, and between a positive electrode and a negative electrode on the DC input side of the inverter A power storage means connected to charge power from the overhead line and regenerative power from the main motor, and to discharge power to the main motor and the auxiliary device when supply of power from the overhead line is stopped. It is characterized by.

  With the above configuration, the power storage means is connected to the DC input side of the inverter that supplies power to the auxiliary equipment, that is, the DC output side of the converter, and is charged by the DC power input from the converter to the inverter. The DC power output from the converter that supplies power to the auxiliary equipment has a lower voltage than the DC power that changes to AC power supplied to the main motor. Therefore, charging or discharging of the power storage means is controlled by direct current power output from the converter without using a DC / DC converter. Thereby, the electrical storage means is charged with electric power from the overhead wire and regenerative electric power from the main motor. The power storage means supplies power to the main motor and auxiliary equipment by discharging. Therefore, for example, even when the electric vehicle stops in a state where current cannot be collected from an overhead line such as a dead section or a power failure, the electric vehicle can be repowered by the electric power generated by the discharge of the storage means. Therefore, energy use efficiency can be increased without increasing the size and complexity of the apparatus.

Schematic which shows the electrical structure of the electric vehicle auxiliary power supply device by 1st Embodiment of this invention. Schematic which shows the electrical structure of the electric vehicle auxiliary power supply device by 2nd Embodiment of this invention. Schematic showing the electrical configuration of a conventional electric vehicle auxiliary power supply

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. Note that, in a plurality of embodiments, substantially the same components are denoted by the same reference numerals, and description thereof is omitted.
(First embodiment)
As shown in FIG. 1, the electric vehicle 10 according to the first embodiment includes a current collector 11 and wheels 12. The current collector 11 is composed of, for example, a pantograph or the like, and is in sliding or rolling contact with the overhead wire 13 to which AC power is supplied. The electric vehicle 10 travels when the wheels 12 roll on the track. The electric vehicle 10 collects electric power from the overhead line 13 by forming an electric circuit between the current collector 11 in contact with the overhead line 13 and the wheel 12 in contact with the track. A circuit breaker 14 and a transformer 15 are connected between the current collector 11 and the wheel 12 in this order from the current collector 11 side. The circuit breaker 14 opens and closes an electric circuit formed between the current collector 11 and the wheel 12. Further, the transformer 15 steps down the AC power collected from the current collector 11. The transformer 15 includes a primary winding 21, a secondary winding 22, and a tertiary winding 23 between the current collector 11 and the wheel 12.

  The electric vehicle 10 includes a converter 32 and an inverter 33 that control electric power supplied to the main motor 31. The electric vehicle 10 is equipped with an electric vehicle auxiliary power supply (hereinafter referred to as “auxiliary power supply”) 40. The auxiliary power supply device 40 includes a converter 41, an inverter 42, and a battery 43 as power storage means. The converter 32 and the converter 41 are AC / DC converters by so-called PWM (Pulse Width Modulation) control that converts AC power into DC power. Specifically, the converter 32 is connected to the secondary winding 22 of the transformer 15. Further, the converter 41 is connected to the tertiary winding 23 of the transformer 15. Thus, the converter 32 and the converter 41 convert the AC power collected from the overhead line 13 by the current collector 11 and transformed by the transformer 15 into DC power, and control and output the voltage of the DC power.

  The inverter 33 is connected to the DC power output side of the converter 32. Inverter 33 converts the DC power input from converter 32 into three-phase AC power and outputs it to main motor 31. Specifically, inverter 33 is configured by a VVVF inverter that outputs three-phase AC power whose voltage and frequency are variable according to the running state of electric vehicle 10 from DC power input from converter 32. Further, the inverter 42 is connected to the DC power output side of the converter 41. The inverter 42 converts the DC power input from the converter 41 into three-phase AC power or single-phase AC power and outputs it. The inverter 42 is configured by a static inverter that outputs AC power having a constant voltage and frequency from DC power input from the converter 41, for example.

  The main motor 31 is a squirrel-cage three-phase induction motor, for example, and is driven by three-phase AC power output from the AC output side of the inverter 33. The main motor 31 is mechanically connected to the wheels 12 via a drive mechanism (not shown). Thereby, the driving force generated from the main motor 31 is transmitted to the wheels 12 via the driving mechanism. As a result, the electric vehicle 10 travels on the track by the driving force generated by the main motor 31.

  One or more auxiliary devices 44 are connected to the AC power output side of the inverter 42. The auxiliary equipment 44 includes various equipment such as air conditioning equipment, lighting, and a compressor, for example. The air conditioner and the lighting perform air conditioning in the cabin of the electric vehicle 10 and lighting in the cabin and outside. The compressor generates compressed air to be supplied to a braking device, an air spring, a door opening / closing device or the like of the electric vehicle 10. The auxiliary device 44 is driven by three-phase AC power or single-phase AC power supplied from the inverter 42.

  The battery 43 as the power storage means is configured by a secondary battery such as a lithium ion battery. Further, the power storage means may be constituted by an electric double layer capacitor instead of the battery 43. Such a battery 43 or an electric double layer capacitor has high durability against repeated charge and discharge, and a sufficient charge capacity is ensured. Battery 43 is connected between the positive electrode and the negative electrode on the DC output side of converter 41. A part of the AC power collected from the overhead line 13 is charged to the battery 43 via the tertiary winding 23 of the transformer 15 and the converter 41. Further, the regenerative power generated in the main motor 31 during braking of the electric vehicle 10 is charged in the battery 43 as necessary.

  Converter 41 controls the output DC voltage. In this case, converter 41 changes the DC voltage applied to battery 43 based on the detected charge capacity of battery 43. Thereby, charging and discharging of battery 43 are controlled by the DC voltage output from converter 41. The voltage extracted from the tertiary winding 23 of the transformer 15 is set lower than the voltage extracted from the secondary winding 22. Therefore, the voltage input from tertiary winding 23 to converter 41 and from converter 41 to battery 43 is also set low. As a result, the insulation specification of the electric circuit from the tertiary winding 23 to the battery 43 is simplified. Thus, by controlling the charging and discharging of the battery 43 by the DC voltage output from the converter 41 provided to supply power to the auxiliary equipment 44, for example, a dedicated DC / DC converter or the like is unnecessary for the battery. In addition, the insulation specification of the circuit around the battery 43 is also simplified. Accordingly, the device can be reduced in size and weight.

Next, the operation of the auxiliary power supply device 40 of the electric vehicle 10 having the above configuration will be described.
When the electric vehicle 10 is in a state where current can be collected from the overhead line 13, the battery 43 is charged by a part of the collected power. The charging rate of the battery 43 is controlled by a DC voltage output from the converter 41. In the case of the first embodiment, a margin is secured in the charging capacity so that the charging rate of the battery 43 is less than 100%. That is, the battery 43 is controlled so as to be always rechargeable.

  When the electric vehicle 10 is in power running, the electric vehicle 10 collects AC power from the overhead line 13 by the current collector 11. The collected AC power is supplied to the main motor 31 via the transformer 15, the converter 32, and the inverter 33. Thereby, the main motor 31 generates a driving force for driving the wheels 12, and the electric vehicle 10 travels. On the other hand, when the electric vehicle 10 is in braking, the electric vehicle 10 performs regenerative braking by causing the main motor 31 to function as a generator. The electric power generated in the main motor 31 at the time of braking is applied to the secondary winding 22 of the transformer 15 via the inverter 33 and the converter 32 contrary to the power running. Here, when the regeneration is functioning effectively, the AC power applied to the secondary winding 22 is returned from the primary winding 21 to the overhead wire 13 via the current collector 11. As a result, the electric power generated in the main motor 31 by braking the electric vehicle 10 is regenerated by being consumed by another electric vehicle traveling in the same feeding section, that is, in the same section.

  On the other hand, when the regeneration is not functioning effectively, that is, when the regeneration is invalidated, the AC power applied to the secondary winding 22 is charged to the battery 43 from the tertiary winding 23 via the converter 41. The For example, when the power consumption of another electric vehicle that is powered in the same section is lower than the regenerative power of the own electric vehicle, when passing through the cross-intersection section, or when there is a power failure, the power generated in the main motor 31 is Regeneration expires that cannot be fully regenerated. When regenerative invalidation occurs in this way, the electric vehicle 10 needs to consume the electric power generated in the main motor 31 as heat, for example, using a resistor (not shown) or the like, and to brake using a mechanical brake. This results in reduced energy efficiency and unnecessary wear on the mechanical brake. In the present embodiment, as described above, a sufficient margin is always secured for the charging rate of the battery 43. Therefore, even when regeneration invalidation occurs in this way, the electric power generated in the main motor 31 is regenerated by charging the battery 43.

  The electric power charged in the battery 43 is consumed by driving the auxiliary device 44 or the main motor 31. For example, when the supply of power from the overhead line 13 is stopped due to a power failure or the like, the air conditioner, illumination, and compressed air of the electric vehicle 10 are driven by the power charged in the battery 43. In this case, the power charged in the battery 43 is converted into AC power by the inverter 42 and then supplied to the auxiliary device 44.

  For example, when the electric vehicle 10 stops in a non-electric section (dead section) such as an alternating-intersection section or an alternating-direct section, the electric vehicle 10 escapes from the non-electric section by the electric power generated by the discharge of the battery 43. In this case, the power charged in the battery 43 is converted into AC power by the converter 41 and then applied to the tertiary winding 23 of the transformer 15. Then, the electric power extracted from the secondary winding 22 of the transformer 15 is converted into DC power by the converter 32, and then converted into AC power again by the inverter 33 and supplied to the main motor 31. The main motor 31 generates driving force by the electric power supplied from the battery 43 in the above procedure, and drives the electric vehicle 10. Thereby, the electric vehicle 10 stopped in the non-electric section can escape from the non-electric section by itself.

  As described above, in the first embodiment described above, the battery 43 is connected to the DC input side of the inverter 42, that is, the DC output side of the converter 41, and is charged by DC power input from the converter 41 to the inverter 42. The DC power output from the converter 41 for supplying power to the auxiliary device 44 is lower in voltage than the DC power output from the converter 32 for supplying power to the main motor 31. Therefore, charging or discharging of the battery 43 is directly controlled by the DC power output from the converter 41 without using a dedicated DC / DC converter. Thereby, the battery 43 is charged with the electric power from the overhead wire 13 and the regenerative electric power from the main motor 31. In particular, when regeneration is invalidated, the electric power generated by the main motor 31 is recovered by charging the battery 43. Therefore, energy use efficiency can be increased without increasing the size and complexity of the apparatus. Further, by collecting the electric power generated by the main motor 31 in the battery 43, the use of a mechanical brake during braking is reduced. Therefore, mechanical brake wear can be reduced.

  In the first embodiment, the battery 43 can also supply power to the main motor 31 by discharging. Therefore, for example, even when the electric vehicle 10 stops in a state where current cannot be collected from the overhead line 13 such as a dead section such as a cross-intersection section or a power failure, the electric vehicle 10 can be repowered by the electric power generated by the discharge of the battery 43. Furthermore, in 1st Embodiment, the battery 43 supplies electric power to auxiliary equipment 44, such as an air conditioning, illumination, and a compressor, by discharging. Therefore, even when the electric vehicle 10 stops in a state where current cannot be collected from the overhead line 13, the electric vehicle 10 can be repowered and power is supplied from the battery 43 to the necessary auxiliary equipment 44. Therefore, the safety of the electric vehicle 10 in an emergency can be improved.

(Second Embodiment)
An auxiliary power supply according to a second embodiment of the present invention is shown in FIG.
As shown in FIG. 2, in the case of the second embodiment, the auxiliary device 44 is composed of two or more devices 441 and 442. 2 shows an example in which the auxiliary device 44 includes two devices 441 and 442 for ease of explanation. A contactor 51 is provided in a circuit connecting the inverter 42 and the device 441, and a contactor 52 is provided in a circuit connecting the inverter 42 and the device 442. Further, the auxiliary power supply device 40 further includes a voltage detection unit 61 and a control unit 62. The voltage detector 61 is connected to the current collector 11 and detects the voltage of the overhead wire 13. The control unit 62 controls the contactor 51 of the device 441 or the contactor 52 of the device 442 based on the voltage of the overhead wire 13 detected by the voltage detection unit 61.

  The battery 43 has a limited charge capacity. For this reason, when power is supplied from the battery 43 to all the devices 441 and 442 constituting the auxiliary device 44 after the supply of AC power from the overhead line 13 is stopped, the charge capacity of the battery 43 is quickly reduced. As a result, neither the device 441 or the device 442 constituting the auxiliary device 44 can be driven. Therefore, in the second embodiment, the control unit 62 detects the voltage of the overhead line 13 by the voltage detection unit 61 and determines whether or not current collection from the overhead line 13 is possible. For example, when the voltage of the overhead line 13 decreases or the voltage of the overhead line 13 becomes 0 due to a power failure, the control unit 62 determines that current collection from the overhead line 13 is impossible. Then, when the control unit 62 determines that the current cannot be collected from the overhead line 13, the contactor 51 of the device 441 or the device 442 of the device 441 that is less necessary among the devices 441 and 442 constituting the auxiliary device 44. The contactor 52 is opened.

  Here, a low necessity device is a device that has a small direct influence on the traveling of the electric vehicle 10 such as lighting and air conditioning, and a high necessity device generates compressed air for braking, for example. Such as a compressor that has a great influence on the safe driving of the electric vehicle 10. That is, in the case of this example, the control unit 62 opens a contactor connected to lighting or air conditioning in order to maintain power supply from the battery 43 to the compressor. As a result, the load required for the battery 43 is reduced, and efficient operation of the battery 43 can be achieved. The priorities of the devices 441 and 442 constituting the auxiliary device 44 that supplies power from the battery 43 can be arbitrarily changed. For example, while maintaining the supply of power to the auxiliary equipment 44 that has a large influence on the safe driving of the electric vehicle 10, priority is given to maintaining air conditioning during the summer, and lighting prior to night. May be.

(Other embodiments)
In the plurality of embodiments described above, a compressor is shown as an example of the auxiliary device 44. Conventional electric vehicles generally include a main compressor for supplying compressed air to a brake and an air spring, and an auxiliary compressor for supplying compressed air to a current collector such as a pantograph. This is because power cannot be obtained when the current collector is stored, so that the auxiliary compressor is first driven by the battery to drive the current collector, and then the current collector is used to collect current from the overhead line to drive the main compressor. In contrast, in the plurality of embodiments of the present invention, the auxiliary device 44 is driven by the battery 43. Therefore, even when the current collector 11 is stored, the main compressor can be driven by the electric power stored in the battery 43. Therefore, the auxiliary compressor can be omitted, and the equipment mounted on the electric vehicle 10 can be reduced.

  The present invention described above is not limited to the above-described embodiment, and can be applied to various embodiments without departing from the gist thereof.

  In the drawings, 10 is an electric vehicle, 13 is an overhead wire, 31 is a main motor, 40 is an auxiliary power supply (electric vehicle auxiliary power supply), 41 is a converter, 42 is an inverter, 43 is a battery (power storage means), and 44 is an auxiliary device. Indicates.

Claims (1)

A transformer for stepping down the AC power collected from the overhead line and supplying it to the main motor;
A converter that converts AC power transformed by the transformer into DC power;
An inverter connected to the DC power output side of the converter, converting the input DC power into AC power and outputting it to auxiliary equipment;
Connected between a positive electrode and a negative electrode on the DC input side of the inverter, charging the power from the overhead line and regenerative power from the main motor, and when the supply of power from the overhead line is stopped, the main motor and the Power storage means for discharging power to the auxiliary equipment;
An electric vehicle auxiliary power supply device comprising:

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