JP2018182918A - Electric power conversion device, electric vehicle, and electric power conversion method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power conversion device which can while keeping a circuit to be directly connected to a fuel battery ungrounded, ground a motor drive circuit for driving a main motor after being supplied with electric power from the fuel cell.SOLUTION: An electric power conversion device comprises: an inverter which converts DC voltage supplied from a fuel battery into AC voltage; a current transformer having a primary side coil to which AC voltage is supplied from the inverter and a secondary side coil insulated from the same; a voltage conversion circuit which generates DC voltage according to the AC voltage supplied from the secondary side coil; a switching circuit which supplies AC voltage supplied from the voltage conversion circuit to a power supply line in a first mode, and supplies AC current supplied from an input terminal to the power supply line in a second mode; and a motor drive circuit which generates drive voltage according to DC voltage supplied from the power supply line. The inverter is electrically insulated from the voltage conversion circuit and the motor drive circuit.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power converter used in an electric vehicle such as a railway vehicle. The present invention also relates to an electric vehicle equipped with such a power conversion device, and a power conversion method used in such a power conversion device.

  BACKGROUND ART In recent years, a railway vehicle has been developed which travels in a electrified section while being supplied with electric power from an overhead wire and which can also travel in a non-electrified section. Some of such railway cars travel in a non-electrified section using electric power supplied from a fuel cell or a storage battery (battery).

  Generally, in a conventional railway vehicle using a fuel cell, one end of a motor drive circuit (or inverter) which converts a DC voltage supplied from an overhead wire or fuel cell into an AC voltage to drive a main motor (motor) The negative terminal of the cell was directly connected, and the fuel cell and the motor drive circuit were not electrically isolated. In addition, the negative electrode terminal of the fuel cell and one end of the motor drive circuit were grounded via the wheel and the rail.

  As a related technology, Patent Document 1 discloses a fuel cell vehicle control device in which the output of a fuel cell is controlled by controlling a direct current voltage by a power storage means, and the output adjustment means of the fuel cell is omitted. The fuel cell vehicle control device includes a power generation unit using a fuel cell, a storage unit for storing electric power, a charge / discharge device for charging / discharging the storage unit, direct current power of the fuel cell, and direct current power of the charge / discharge unit. It has an inverter for converting into AC power to drive a motor. As shown in FIG. 1 of Patent Document 1, the negative electrode terminal of the fuel cell 1 is directly connected to one end of the inverter 6, and the fuel cell 1 and the inverter 6 are not electrically insulated.

  Further, Patent Document 2 discloses a voltage conversion device for a hybrid railway vehicle that can switch between using a fuel cell in a non-electrifying section and using a power supply from an overhead wire in the electrifying section. . As shown in FIG. 1 or 5 of Patent Document 2, the negative electrode terminal of the fuel cell 50 is directly connected to one end of the inverter 100, and the fuel cell 50 and the inverter 100 are electrically insulated. Absent.

  Further, in Patent Document 3, DC power generation means having a fuel cell and output adjustment means, inverter means for converting DC power generated by the DC power generation means into AC power, and function of charging and discharging DC power SUMMARY OF THE INVENTION A drive system for a railway vehicle is disclosed which comprises: Similarly, Patent Document 4 discloses a drive device of a railway vehicle including a fuel cell and an output adjustment unit that adjusts the output power of the fuel cell.

  Further, Patent Document 5 discloses a drive system corresponding to a plurality of different power sources (overhead wire, a generator driven by an engine, a fuel cell) in each of the electrified section and the non-electrified section. However, Patent Documents 3 to 5 do not specifically disclose the specific configuration of each means, and grounding or non-grounding of the fuel cell and the inverter means.

Unexamined-Japanese-Patent No. 2008-141879 (Paragraph 0004-0005, FIG. 1) JP, 2015-61392, A (paragraph 0006, FIG. 1, FIG. 5) JP, 2004-282859, A (claim 2, claim 8) JP, 2010-11683, A (claim 4) JP 2014-140294 A (abstract)

  As described above, in a conventional railway vehicle using a fuel cell, the negative electrode terminal of the fuel cell and one end of the motor drive circuit are grounded, but a large-sized fuel cell for recent mobile units is not grounded Is required. By setting the fuel cell to an ungrounded state, current does not flow due to the electric leakage if the electric leakage does not occur at two places of different potentials in the fuel cell or its peripheral circuit. Therefore, when an electrical leakage occurs at one place, the electrical leakage accident can be prevented in advance by detecting the electrical leakage. In addition, manufacturers of large-sized fuel cells for railway vehicles also tend to guarantee the operation of the fuel cell in a state where the circuit directly connected to the fuel cell is not grounded.

  On the other hand, it is desirable that the motor drive circuit for driving the main motor is grounded via the wheels and the rails as in the prior art. By grounding the motor drive circuit, the potential of each part of the motor drive circuit is stabilized, so that it becomes easy to detect an electric leakage and it is possible to secure the safety of the operation. In addition, if the entire circuit including the motor drive circuit is not grounded, such as a car or a bus traveling with a fuel cell, the circuit of the conventional railway vehicle can not be used, so the effort for developing a new circuit And there is a problem of cost increase.

  Then, in view of the above-mentioned point, the 1st object of the present invention is a motor drive circuit etc. which is supplied with electric power from a fuel cell or an overhead wire and drives a main motor, making a circuit directly connected to a fuel cell ungrounded. To provide a power converter capable of grounding the A second object of the present invention is to provide an electric vehicle which can be run in a non-electrified section and an electrified section by mounting such a power conversion device. Furthermore, a third object of the present invention is to provide a power conversion method used in such a power converter.

  In order to solve at least a part of the above problems, in the power conversion device according to the first aspect of the present invention, an inverter that converts a DC voltage supplied from a fuel cell into an AC voltage and an AC voltage is supplied from the inverter A transformer having a primary side winding and a secondary side winding electrically isolated from the primary side winding, and a direct current based on an alternating voltage supplied from the secondary side winding of the transformer In the first mode, at least a DC voltage supplied from the voltage conversion circuit is supplied to the power supply line, and in the second mode, a DC voltage supplied from the input terminal is supplied to the power supply line. Whether the inverter includes a voltage conversion circuit and a motor drive circuit, and a switch circuit for supplying power and a motor drive circuit for generating a drive voltage for the main motor based on a DC voltage supplied from the power supply line Electrically insulated.

  According to a first aspect of the present invention, an inverter converts a DC voltage supplied from a fuel cell into an AC voltage and supplies it to the primary winding of a transformer, and a voltage conversion circuit A DC voltage is generated based on the AC voltage supplied from the next winding and supplied to the motor drive circuit. With such a configuration, since the inverter is electrically isolated from the voltage conversion circuit and the motor drive circuit, power is supplied from the fuel cell or the overhead wire while the circuit directly connected to the fuel cell is not grounded. It becomes possible to ground the motor drive circuit etc. which drive an electric motor.

  An electric vehicle according to a second aspect of the present invention includes the power conversion device according to the first aspect of the present invention, and a plurality of wheels rotatably mounted on a vehicle body on which the power conversion device is installed, But are electrically isolated from the wheels. According to the second aspect of the present invention, when the electric vehicle travels on the grounded rail, the inverter is electrically isolated from the rail, so the circuit directly connected to the fuel cell is not grounded. At the same time, electric power is supplied from the fuel cell or the overhead wire, and it becomes possible to ground the motor drive circuit or the like for driving the main motor.

  According to a third aspect of the present invention, there is provided a power conversion method comprising: an inverter for converting a DC voltage into an AC voltage; a primary side winding supplied with an AC voltage from the inverter; and an electric primary side winding. A transformer having an insulated secondary side winding, a voltage conversion circuit generating a direct current voltage based on an alternating current voltage supplied from the secondary side winding of the transformer, and a direct current voltage supplied from a power supply line A power conversion method used in a power conversion device including a motor drive circuit for generating a drive voltage of a main motor based thereon, which supplies a DC voltage generated by the voltage conversion circuit to a power supply line in a first mode. (A) controlling the switching circuit and, in the first mode, supplying a control signal to the inverter electrically isolated from the grounded rail Step (b) of converting the supplied DC voltage into an AC voltage and supplying it to the primary winding of the transformer; and in the first mode, using the voltage conversion circuit, the secondary winding of the transformer And (c) generating a DC voltage based on the AC voltage supplied from the power supply, and supplying a control signal to the motor drive circuit electrically connected to the grounded rail in the first mode. Step (d) of generating a drive voltage of the main motor based on the DC voltage supplied from the line and controlling the switching circuit to supply the DC voltage supplied from the input terminal to the power supply line in the second mode Step (e) and, in the second mode, by supplying a control signal to the motor drive circuit electrically connected to the grounded rail, the DC voltage supplied from the power supply line is And a step (f) to generate a driving voltage of the main electric motor Zui.

  According to a third aspect of the present invention, in the first mode, an inverter electrically isolated from a grounded rail is used to convert a DC voltage supplied from a fuel cell into an AC voltage for transformer Supply to the primary side winding, and using the voltage conversion circuit to generate a direct current voltage based on the alternating current voltage supplied from the secondary side winding of the transformer and supply it to the power supply line. The directly connected circuit can be ungrounded. Further, in the first and second modes, the motor drive circuit or the like that generates the drive voltage of the main motor can be grounded based on the DC voltage supplied from the power supply line.

BRIEF DESCRIPTION OF THE DRAWINGS It is a circuit diagram which shows the structural example of an electric vehicle provided with the power converter device which concerns on the 1st Embodiment of this invention. It is a figure which shows the example of the waveform of the control signal supplied to the inverter shown in FIG. It is a figure which shows the connection state in the 2nd mode of the electric vehicle shown in FIG. FIG. 5 is a diagram showing an example of waveforms of control signals supplied to the DC / DC converter shown in FIGS. 1 and 3 at the time of step-down. FIG. 5 is a diagram showing an example of waveforms of control signals supplied to the DC / DC converter shown in FIG. 1 and FIG. 3 at the time of boosting. It is a circuit diagram showing an example of composition of an electric vehicle provided with a power converter concerning a 2nd embodiment of the present invention. It is a figure which shows the example of the waveform of the control signal supplied to the PWM converter shown in FIG. It is a circuit diagram showing an example of composition of an electric vehicle provided with a power converter concerning a 3rd embodiment of the present invention. It is a flowchart which shows the power conversion method which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same reference numerals are given to the same components, and the overlapping description is omitted.
First Embodiment
FIG. 1: is a circuit diagram which shows the structural example of an electric vehicle provided with the power converter device which concerns on the 1st Embodiment of this invention. The electric vehicle travels using electric power supplied from the overhead wire in the electrification section, and can travel also in a non-electrification section (under a non-interconnection line). FIG. 1 shows a connection state in a first mode in which the electric vehicle travels using power supplied from the fuel cell FC1.

  As shown in FIG. 1, the electric vehicle includes a pantograph 10, a plurality of wheels 12, a ground switch circuit 13, high speed circuit breakers 21 to 25, start switch circuits 31 to 35, and a main motor 40. And the auxiliary circuit power supply device (auxiliary device) 50 may be included. In addition, the electric vehicle includes a power conversion device including inverter 60, a fuel cell FC1, a storage battery BAT, resistors R1 to R6, capacitors C1 to C5, inductors L4 and L5, and a thyristor TH1. But it is good.

  The pantograph 10 is mounted on the roof of the electric vehicle and supplied with power from overhead wires in the electrified section. The plurality of wheels 12 are rotatably attached to a vehicle body in which a power conversion device or the like is installed, and are in contact with a grounded rail to be supplied with a ground potential (0 V). Certain of the wheels 12 are driven by the main motor 40.

  The high speed circuit breakers 21 to 25 protect the internal circuit of the electric vehicle by interrupting the circuit when a short circuit fault current or the like flows. The ground switch circuit 13 is formed of, for example, a relay circuit or an electronic switch, and supplies a ground potential from the plurality of wheels 12 to the ground line GL when it is turned on.

  The start switch circuits 31 to 35 are configured by, for example, a relay circuit, an electronic switch, or the like, and are used at the start of each part of the power conversion device. For example, when the fuel cell FC1 starts power feeding, the start switch circuit 31 is turned off, and power is supplied from the fuel cell FC1 to the inverter 60 via the resistor R1, thereby causing a sharp rush current. Is suppressed. Thereafter, the start switch circuit 31 is turned on, and power is supplied from the fuel cell FC1 to the inverter 60 via the start switch circuit 31.

  The main motor 40 is formed of, for example, an induction motor (IM), and is supplied with three-phase AC voltages (U phase, V phase, W phase) during power running to drive the wheels, and brakes the wheels during regeneration. To generate an alternating electromotive force. The auxiliary circuit power supply device 50 includes, for example, an inverter, and converts the DC voltage supplied from the power supply line PL into an AC voltage to supply the AC voltage to in-vehicle equipment such as an air conditioner other than for traveling.

  The fuel cell FC1 generates electric energy using a reaction reverse to the electrolysis of water, for example, by chemically reacting oxygen as a positive electrode agent and hydrogen as a negative electrode agent. In the non-electrified section, fuel consumed in fuel cell FC1 can be saved by utilizing storage battery BAT in addition to fuel cell FC1. As the storage battery BAT, for example, a chargeable lithium ion secondary battery or the like is used. The storage battery BAT is mainly charged in the electrified section, and supplies power to the power conversion device in the non-electrified section.

<Power converter>
The power conversion device according to the first embodiment includes an inverter 60, a transformer (insulation transformer) 70, a voltage conversion circuit 80, a switching circuit 90, an input terminal 91, a motor drive circuit 100, and DC / DC. The converter 110 may include the control unit 120, the storage unit 130, and the control signal transmission unit 140.

  The inverter 60 converts the DC voltage supplied from the fuel cell FC1 into an AC voltage. The transformer 70 has a primary side winding 71 to which an AC voltage is supplied from the inverter 60 and a secondary side winding 72 electrically isolated from the primary side winding 71. The voltage conversion circuit 80 generates a DC voltage based on the AC voltage supplied from the secondary winding 72 of the transformer 70.

  The switching circuit 90 includes, for example, a plurality of relay circuits or electronic switches, and performs switching operation according to a control signal supplied from the control unit 120. A direct current voltage is supplied to the input terminal 91 from the overhead wire through the pantograph 10 in the direct current electrification section. Switching circuit 90 supplies the DC voltage supplied from voltage conversion circuit 80 to power supply line PL in the first mode, and supplies the DC voltage supplied from input terminal 91 to power supply line PL in the second mode. Do.

  Thus, the electric vehicle travels using the power supplied from the fuel cell FC1 in the first mode, and travels using the power supplied from the overhead wire through the pantograph 10 in the second mode. In addition, when the storage battery BAT is sufficiently charged, it is possible to switch the operation of the power conversion device so that the electric vehicle travels using the power supplied from the storage battery BAT in the third mode. It is.

  Motor drive circuit 100 generates a drive voltage for main motor 40 based on the DC voltage supplied from power supply line PL. The DC / DC converter 110 steps down the DC voltage of the power supply line PL to charge the storage battery BAT or boosts the DC voltage output from the storage battery BAT and supplies it to the power supply line PL.

  The control unit 120 generates control signals for controlling various circuit breakers and switch circuits, the inverter 60, the switching circuit 90, the motor drive circuit 100, the DC / DC converter 110, and the like. Further, the control unit 120 sets the power conversion device to the first mode when the DC voltage of the input terminal 91 is less than or equal to a predetermined threshold, and the DC voltage of the input terminal 91 is larger than the predetermined threshold. The power converter may be set to the second mode. For that purpose, a voltmeter for measuring the voltage of the input terminal 91 is provided in the electric vehicle. Alternatively, the control unit 120 may set the power conversion device to any one of the first mode to the third mode according to the operation of the operator.

  The control unit 120 may be configured by an analog circuit or may be configured by a digital circuit. Alternatively, the control unit 120 may be configured by a central processing unit (CPU) and software (power conversion program) for causing the CPU to execute various procedures. The software is stored in the storage medium of the storage unit 130. As the recording medium, a built-in hard disk, an external hard disk, a flexible disk, an MO, an MT, a CD-ROM, a DVD-ROM, or various memories can be used.

  In the above, the inverter 60 directly connected to the fuel cell FC1 is electrically isolated from the voltage conversion circuit 80, the motor drive circuit 100 and the like by the transformer 70. Thus, the inverter 60 is electrically isolated from the plurality of wheels 12 of the electric vehicle and is not grounded. Therefore, the fuel cell FC1 can be used in an ungrounded state.

  On the other hand, the ground switch circuit 13 electrically connects the voltage conversion circuit 80, the motor drive circuit 100 and the like to the plurality of wheels 12 of the electric vehicle when it is turned on. That is, when the ground switch circuit 13 is turned on, the ground line GL connected to the voltage conversion circuit 80 and the motor drive circuit 100 is grounded via the plurality of wheels 12 and rails of the electric vehicle. . Therefore, the potential of each part such as the voltage conversion circuit 80 and the motor drive circuit 100 can be stabilized.

  In the first mode, the electric vehicle travels using the power supplied from the fuel cell FC1. Therefore, control unit 120 controls switching circuit 90 to supply the DC voltage supplied from voltage conversion circuit 80 to power supply line PL. Further, the ground switch circuit 13, the high speed circuit breakers 21 to 23, and the start switch circuits 31 to 33 are in the on state.

<Inverter>
When the high speed circuit breaker 21 and the start switch circuit 31 are in the on state, the fuel cell FC1 is connected to the smoothing capacitor C1 and the inverter 60 to supply the inverter 60 with a DC voltage. The inverter 60 has an output node N1 connected to one end of the primary side winding 71 of the transformer 70, and an output node N2 connected to one end of the capacitor C2. The other end of the primary side winding 71 of the transformer 70 is connected to the other end of the capacitor C2.

  The inverter 60 converts the DC voltage supplied from the fuel cell FC1 into an AC voltage and supplies it to the output nodes N1 and N2. For example, the inverter 60 includes switching elements Q11 to Q14 and diodes D11 to D14 connected in parallel to the switching elements Q11 to Q14, respectively. In the example shown in FIG. 1, each of switching elements Q11 to Q14 is an IGBT (insulated gate bipolar transistor).

  The switching elements Q11 and Q12 have collectors connected to the positive electrode terminal of the fuel cell FC1, emitters respectively connected to the output nodes N1 and N2, and gates to which respective control signals are supplied. The diodes D11 and D12 have a cathode connected to the positive electrode terminal of the fuel cell FC1 and an anode connected to the output nodes N1 and N2, respectively.

  Switching elements Q13 and Q14 each have a collector connected to output nodes N1 and N2, an emitter connected to the negative electrode terminal of fuel cell FC1, and a gate to which each control signal is supplied. The diodes D13 and D14 have cathodes respectively connected to the output nodes N1 and N2 and an anode connected to the negative electrode terminal of the fuel cell FC1.

  Since inverter 60 is electrically isolated from ground line GL and is in a floating state, control signal transmission unit 140 transmits control signal from control unit 120 electrically connected to ground line GL to inverter 60. Is provided. The control signal transmission unit 140 is configured of, for example, an optical signal transmission circuit including a light emitting element and a photoelectric conversion element, or a small-sized insulating transformer.

  The switching elements Q11 to Q14 perform a switching operation in accordance with a control signal supplied to the gate from the control unit 120 via the control signal transmission unit 140. Thus, the inverter 60 converts, for example, the DC voltage 700 V supplied from the fuel cell FC1 into an AC voltage, and supplies the AC voltage to the primary winding 71 of the transformer 70.

  FIG. 2 is a diagram showing an example of waveforms of control signals supplied to the inverter shown in FIG. Control unit 120 alternately activates control signals G11 and G14 supplied to the gates of switching elements Q11 and Q14 and control signals G12 and G13 supplied to the gates of switching elements Q12 and Q13, respectively, to a high level. Turn

  However, since switching elements Q11 to Q14 require time to transition from the on state to the off state to recover the voltage blocking capability, the activation periods of control signals G11 and G14 are required to avoid a short circuit. A margin of time Δt is provided between the activation periods of control signals G12 and G13. Further, the magnitude of the AC voltage output from the inverter 60 may be adjusted by changing the time Δt by PWM (pulse width modulation) control.

  Switching elements Q11 and Q14 are turned on in a period in which control signals G11 and G14 are activated to a high level. Thus, current flows from the positive electrode terminal of the fuel cell FC1 to the negative electrode terminal of the fuel cell FC1 via the switching element Q11, the primary winding 71 of the transformer 70, the capacitor C2 and the switching element Q14.

  On the other hand, switching elements Q12 and Q13 are turned on in a period in which control signals G12 and G13 are activated to the high level. Thus, current flows from the positive electrode terminal of the fuel cell FC1 to the negative electrode terminal of the fuel cell FC1 via the switching element Q12, the capacitor C2, the primary winding 71 of the transformer 70, and the switching element Q13.

  When the inverter 60 generates an AC voltage having a frequency as low as that of the commercial power supply (50 Hz to 60 Hz), the transformer 70 becomes large in size to transmit the AC voltage of a low frequency, and the switching element Q11 to Q14 also become large. So, in this embodiment, the inverter 60 produces | generates the alternating current voltage which has a high frequency within the range of 8 kHz-12 kHz which is one hundred times or more of the frequency of a commercial power source, for example.

<Capacitor>
Referring back to FIG. 1, capacitor C 2 is connected between output node N 2 of inverter 60 and primary side winding 71 of transformer 70 to form a series resonant circuit with the inductance component of transformer 70. The resonant frequency f of this series resonant circuit is expressed by the following equation using an inductance L viewed from the primary side of the transformer 70 and a capacitance C of the capacitor C2.
f = 1 / {2π (LC) ^1/2 }

The inductance L and the capacitance C are set such that the resonant frequency f is approximately equal to the frequency of the AC voltage generated by the inverter 60. Thereby, the AC voltage value supplied to the primary side winding 71 of the transformer 70 can be increased compared to the AC voltage value between the output node N1 and the output node N2 of the inverter 60. For example, it is possible to inverter 60 is supplied to the case of converting a DC voltage 700V AC voltage 700V _0-P, an AC voltage of 1400 V _0-P to the primary winding 71 of the transformer 70.

<Transformer and voltage conversion circuit>
Transformer 70, depending on the turns ratio of the number of turns _{n 1} of the primary winding 71 and the number of turns _{n 2} of the secondary winding 72 _(n 2 / _{n 1),} is supplied to the primary winding 71 AC voltage is multiplied by (n ₂ / n ₁ ) and output from the secondary winding 72.

The voltage conversion circuit 80 generates a DC voltage based on the AC voltage output from the secondary winding 72 of the transformer 70. The capacitor C3 smoothes the DC voltage generated by the voltage conversion circuit 80. The turns ratio (n ₂ / n ₁ ) of the transformer 70 is determined, for example, such that the DC voltage generated by the voltage conversion circuit 80 is 1500V.

  In the first embodiment, the voltage conversion circuit 80 includes a plurality of bridge-connected diodes D21 to D24 that rectify an AC voltage supplied from the secondary winding 72 of the transformer 70 to generate a DC voltage. It is composed of a rectifier circuit. Diodes D21 and D22 have a cathode connected to power supply line PL and an anode connected to both ends of secondary winding 72 of transformer 70, respectively. The diodes D23 and D24 have cathodes respectively connected to both ends of the secondary winding 72 of the transformer 70, and an anode connected to the ground line GL.

  As in the first embodiment, when the inverter 60 generates an alternating current signal having a high frequency of about 8 kHz to 12 kHz, it is possible to perform a rectifying operation by performing on / off control of a transistor with a control signal of a higher frequency. If the rectification operation is performed using a diode, the stability is high and the power loss can be reduced.

<Motor drive circuit>
In the first mode, switching circuit 90 supplies the DC voltage generated by voltage conversion circuit 80 to power supply line PL. The DC voltage supplied to the power supply line PL is supplied to the smoothing capacitor C4 and the motor drive circuit 100 via the inductor L4. The inductor L4 and the capacitor C4 constitute a low pass filter, and smoothes the DC voltage supplied to the motor drive circuit 100.

  The motor drive circuit 100 generates a drive voltage of the main motor 40 based on the DC voltage supplied from the power supply line PL under the control of the control unit 120. The motor drive circuit 100 includes, for example, a VVVF (variable voltage variable frequency) inverter or the like, and converts a DC voltage supplied from the power supply line PL into an AC voltage.

  Motor drive circuit 100 includes, for example, switching elements Q31 to Q36 and diodes D31 to D36 connected in parallel to switching elements Q31 to Q36, respectively, to supply a three-phase alternating voltage to main motor 40. In the example shown in FIG. 1, each of switching elements Q31 to Q36 is an IGBT.

  Switching elements Q31 to Q33 have collectors connected to power supply line PL via inductor L4, emitters connected to three terminals of main motor 40, and gates to which respective control signals are supplied. ing. Diodes D31 to D33 have a cathode connected to power supply line PL via inductor L4, and an anode connected to three terminals of main motor 40, respectively.

  Switching elements Q34 to Q36 each have a collector connected to each of three terminals of main motor 40, an emitter connected to ground line GL, and a gate to which each control signal is supplied. The diodes D34 to D36 have cathodes respectively connected to three terminals of the main motor 40, and an anode connected to the ground line GL.

Switching elements Q31 to Q36 perform a switching operation according to a control signal supplied from control unit 120 to the gate. Thereby, the motor drive circuit 100 converts, for example, the DC voltage 1500 V supplied from the power supply line PL into a three-phase AC voltage 1500 V _{0 -P} to generate a drive voltage of the main motor 40. The main motor 40 rotates the wheels in accordance with the drive voltage supplied from the motor drive circuit 100, whereby the electric vehicle travels.

  The motor drive circuit 100 converts the DC voltage supplied to the power supply line PL into a three-phase AC voltage and supplies it to the main motor 40 during powering, and converts the AC electromotive force generated in the main motor 40 to the DC voltage during regeneration. It converts and supplies to the power supply line PL. This DC voltage is used to charge storage battery BAT or supplied to another electric vehicle via an overhead wire.

  FIG. 3 is a view showing a connection state in the second mode of the electric vehicle shown in FIG. In the DC electrification section, a DC voltage is supplied from the overhead wire to the input terminal 91 via the pantograph 10. Therefore, the electric vehicle travels in the second mode using the power supplied from the overhead line.

  For that purpose, the control unit 120 controls the switching circuit 90 so as to supply the DC voltage supplied from the input terminal 91 to the power supply line PL. Further, the ground switch circuit 13, the high speed circuit breaker 23, and the start switch circuit 33 are in the ON state, and the high speed circuit breakers 21 and 22 and the start switch circuits 31 and 32 are in the OFF state. .

<DC / DC converter>
DC / DC converter 110 is used when charging from power supply line PL to storage battery BAT or discharging from storage battery BAT to power supply line PL. When charging and discharging storage battery BAT, control unit 120 controls high speed circuit breakers 24 and 25 and start switch circuits 34 and 35 in the ON state.

  DC / DC converter 110 includes, for example, switching elements Q41 and Q42, diodes D41 and D42 connected in parallel to switching elements Q41 and Q42, a capacitor C6, and an inductor L6, respectively. In the example shown in FIGS. 1 and 3, each of switching elements Q41 and Q42 is an IGBT.

  Capacitor C6 smoothes the voltage across the series circuit of switching elements Q41 and Q42, and forms a low pass filter with inductor L5. Further, when the potential of the power supply line PL is to be rapidly reduced, the control unit 120 controls the thyristor TH1 to be in the on state, whereby the power supply line PL is connected via the inductor L5, the resistor R6, and the thyristor TH1. , Current flows to the ground line GL.

  Switching element Q41 has a collector connected to power supply line PL via inductor L5, an emitter connected to inductor L6, and a gate to which a control signal is supplied. Diode D41 has a cathode connected to power supply line PL via inductor L5 and an anode connected to inductor L6.

  Switching element Q42 has a collector connected to inductor L6, an emitter connected to ground line GL, and a gate to which a control signal is supplied. The diode D42 has a cathode connected to the inductor L6 and an anode connected to the ground line GL.

  The charging voltage of storage battery BAT is, for example, 600 V to 1000 V, and when charging storage battery BAT from power supply line PL, DC / DC converter 110 is a DC voltage (for example, 1500 V) supplied from power supply line PL. Step-down to generate a step-down voltage (eg, 600 V to 1000 V).

  FIG. 4 is a diagram showing an example of waveforms of control signals supplied to the DC / DC converter shown in FIGS. 1 and 3 at the time of step-down. The control unit 120 periodically activates the control signal G41 supplied to the gate of the switching element Q41 to a high level, and maintains the control signal G42 supplied to the gate of the switching element Q42 at a low level. Accordingly, switching element Q41 is periodically turned on, and switching element Q42 remains off.

  In a period in which control signal G41 is activated to the high level, switching element Q41 is turned on. Thereby, current flows from the power supply line PL to the positive electrode terminal of the storage battery BAT through the inductor L5, the switching element Q41, and the inductor L6. At this time, electrical energy is converted to magnetic energy and accumulated in the inductor L6. Also, the diode D42 is turned off.

  On the other hand, in a period in which control signal G41 is inactivated to low level, switching element Q41 is turned off. At that time, the magnetic energy stored in the inductor L6 is released as electric energy, and current flows from the ground line GL to the positive electrode terminal of the storage battery BAT through the diode D42 and the inductor L6.

  Thus, DC / DC converter 110 operates as a step-down chopper that steps down the DC voltage supplied from power supply line PL and supplies the step-down voltage to storage battery BAT. The value of the step-down voltage can be controlled to a desired value by the duty ratio or the like of the control signal supplied to the gate of switching element Q41.

  Capacitor C5, together with inductor L6, constitutes a low pass filter, and smoothes the step-down voltage supplied to storage battery BAT. By supplying the step-down voltage to storage battery BAT, charging of storage battery BAT is performed. Thus, the storage battery BAT can be charged mainly in the electrification section. When storage battery BAT is sufficiently charged, control unit 120 may deactivate control signal G41 to a low level, or may control high speed circuit breaker 24 or 25 to an off state.

  In the non-electrified section, DC / DC converter 110 may boost the DC voltage output from storage battery BAT to generate a boosted voltage and supply the boosted voltage to power supply line PL. Thus, the electric vehicle can travel using the power supplied from storage battery BAT (third mode). In the third mode, the control unit 120 may control the switching circuit 90 in the non-connection state, or the high speed circuit breaker 22 may be in the OFF state.

  FIG. 5 is a diagram showing an example of waveforms of control signals supplied to the DC / DC converter shown in FIG. 1 and FIG. 3 at the time of boosting. The control unit 120 maintains the control signal G41 supplied to the gate of the switching element Q41 at the low level, and periodically activates the control signal G42 supplied to the gate of the switching element Q42 to the high level. Therefore, switching element Q41 remains in the off state, and switching element Q42 is periodically turned on.

  During a period in which control signal G42 is activated to the high level, switching element Q42 is turned on. Thus, current flows from the positive electrode terminal of storage battery BAT to ground line GL via inductor L6 and switching element Q42. At this time, electrical energy is converted to magnetic energy and accumulated in the inductor L6. Also, the diode D41 is turned off.

  On the other hand, in a period in which control signal G42 is inactivated to low level, switching element Q42 is turned off. At this time, the magnetic energy stored in the inductor L6 is released as electric energy, and current flows from the positive electrode terminal of the storage battery BAT to the power supply line PL through the inductor L6, the diode D41, and the inductor L5.

  Thereby, DC / DC converter 110 operates as a step-up chopper for boosting the DC voltage supplied from storage battery BAT to supply the boosted voltage to power supply line PL. The value of the boosted voltage can be controlled to a desired value by the duty ratio or the like of the control signal supplied to the gate of switching element Q42.

  According to the first embodiment of the present invention, in the power converter, the inverter 60 converts the DC voltage supplied from the fuel cell FC1 into an AC voltage and supplies it to the primary winding 71 of the transformer 70. The voltage conversion circuit 80 generates a DC voltage based on the AC voltage supplied from the secondary winding 72 of the transformer 70 and supplies the DC voltage to the motor drive circuit 100. With such a configuration, inverter 60 is electrically isolated from voltage conversion circuit 80 and motor drive circuit 100.

  In addition, the electric vehicle includes the power conversion device described above and a plurality of wheels 12 rotatably mounted on a vehicle body on which the power conversion device is installed, and the inverter 60 is electrically isolated from the plurality of wheels 12 ing. Thus, when the electric vehicle travels on a grounded rail, the inverter 60 is electrically isolated from the rail. Therefore, it is possible to ground the motor drive circuit 100 or the like that is supplied with power from the fuel cell FC1 or the overhead wire to drive the main motor 40 while the circuit directly connected to the fuel cell FC1 is not grounded.

Second Embodiment
FIG. 6 is a circuit diagram showing a configuration example of an electric vehicle provided with a power converter according to a second embodiment of the present invention. FIG. 6 shows the connection state in the first mode in which the electric vehicle travels using the power supplied from the fuel cell FC1.

  In the second embodiment, a PWM converter 80 a is used as a voltage conversion circuit, instead of the voltage conversion circuit 80 in the first embodiment shown in FIGS. 1 and 3. The frequency of the AC voltage generated by the inverter 60 is, for example, in the range of 200 Hz to 1 kHz, which is three or more times the frequency of the commercial power supply, and the capacitor C2 for generating resonance is omitted. In other respects, the second embodiment may be similar to the first embodiment.

  The PWM converter 80a converts the AC voltage supplied from the secondary winding 72 of the transformer 70 into a DC voltage (DC link voltage). At that time, the AC voltage generated by the inverter 60 is supplied to the PWM converter 80 a via the leakage inductance of the transformer 70. For example, the PWM converter 80a includes switching elements Q51 to Q54 and diodes D51 to D54 connected in parallel to the switching elements Q51 to Q54, respectively. In the example shown in FIG. 6, each of switching elements Q51 to Q54 is an IGBT.

  Switching elements Q51 and Q52 have collectors connected to power supply line PL, emitters connected respectively to both ends of secondary side winding 72 of transformer 70, and gates to which respective control signals are supplied. ing. Diodes D51 and D52 have a cathode connected to power supply line PL, and an anode connected to both ends of secondary winding 72 of transformer 70, respectively.

  Switching elements Q53 and Q54 have collectors respectively connected to both ends of secondary side winding 72 of transformer 70, emitters connected to ground line GL, and gates to which respective control signals are supplied. ing. The diodes D53 and D54 have cathodes respectively connected to both ends of the secondary winding 72 of the transformer 70, and an anode connected to the ground line GL.

  Switching elements Q51 to Q54 perform a switching operation in accordance with a control signal supplied from control unit 120 to the gate. Thereby, the PWM converter 80a converts the AC voltage supplied from the secondary winding 72 of the transformer 70 into a DC link voltage (for example, 1500 V) and supplies it to the power supply line PL. The DC link voltage refers to a pulsating DC voltage generated across the capacitor C3. The pulsation amplitude of the DC link voltage can be reduced by increasing the capacitance of the capacitor C3.

  FIG. 7 is a diagram showing an example of waveforms of control signals supplied to the PWM converter shown in FIG. Control unit 120 alternately activates control signals G51 and G53 supplied to the gates of switching elements Q51 and Q53 to high levels, and controls signals G52 and G54 supplied to the gates of switching elements Q52 and Q54, respectively. Are alternately activated to a high level. Therefore, switching elements Q51 and Q53 are alternately turned on, and switching elements Q52 and Q54 are alternately turned on.

  Here, an example of a method of generating the control signals G51 to G54 will be described. The upper part of FIG. 7 shows the waveforms of the triangular waves carriers VC1 and VC2 of opposite phase to each other, and the waveform of the unit sine wave (modulated wave) VM synchronized with the AC voltage supplied from the secondary side winding 72 of the transformer 70. It is shown. In the example shown in FIG. 7, the amplitudes of the triangular wave carriers VC1 and VC2 are normalized to "1".

  The control unit 120 activates the control signal G51 to a high level and inactivates the control signal G53 to a low level in a period in which the modulation wave VM is larger than the triangular wave carrier VC1. Further, the control unit 120 deactivates the control signal G51 to low level and activates the control signal G53 to high level in a period in which the modulation wave VM is smaller than the triangular wave carrier VC1.

  Further, the control unit 120 activates the control signal G52 to a high level and deactivates the control signal G54 to a low level in a period in which the modulation wave VM is smaller than the triangular wave carrier VC2. In addition, the control unit 120 deactivates the control signal G52 to low level and activates the control signal G54 to high level in a period in which the modulation wave VM is larger than the triangular wave carrier VC2.

  As a result, when the DC link voltage generated across the capacitor C3 is Vd, the inter-line voltage (voltage command value) Vc which is the voltage across the secondary winding 72 of the transformer 70 is modulated. In the positive half cycle of the wave VM, it becomes "0" and Vd alternately, and in the negative half cycle of the modulation wave VM, it becomes "0" and -Vd alternately.

  Thus, the PWM converter 80a converts the AC voltage supplied from the secondary winding 72 of the transformer 70 into a DC link voltage and supplies the DC link voltage to the power supply line PL. The value of the DC link voltage can be controlled to a desired value by the cycle or duty ratio of the control signal supplied to the gates of switching elements Q51-Q54. Therefore, the degree of freedom of the turns ratio between the primary winding 71 and the secondary winding 72 of the transformer 70 is increased.

  The control of the DC link voltage supplied to the power supply line PL may be performed by adjusting the magnitude of the AC voltage output from the inverter 60. In that case, switching elements Q51 to Q54 may be omitted in PWM converter 80a, and a configuration similar to that of voltage conversion circuit 80 shown in FIGS. 1 and 3 may be employed.

  The motor drive circuit 100 generates the drive voltage of the main motor 40 based on the DC link voltage supplied from the PWM converter 80a via the power supply line PL under the control of the control unit 120. Thus, the electric vehicle travels using the power supplied from the fuel cell FC1.

  According to a second embodiment of the present invention, inverter 60 is electrically isolated from PWM converter 80a and motor drive circuit 100. Therefore, it is possible to ground the motor drive circuit 100 or the like that is supplied with power from the fuel cell FC1 or the overhead wire to drive the main motor 40 while the circuit directly connected to the fuel cell FC1 is not grounded.

Third Embodiment
FIG. 8 is a circuit diagram showing a configuration example of an electric vehicle provided with a power converter according to a third embodiment of the present invention. FIG. 8 shows the connection in the first mode in which the electric vehicle travels using the power supplied from the two fuel cells FC1 and FC2.

  In the third embodiment, in addition to the configuration of the second embodiment shown in FIG. 6, the electric vehicle includes a second fuel cell FC2, a high speed circuit breaker 26, a start switch circuit 36, and a resistor. It further includes R7 and a capacitor C7. In addition, the power conversion device further includes a second inverter 60a, a second transformer 70a, and a second PWM converter 80b. In other respects, the third embodiment may be similar to the second embodiment.

  When the high-speed circuit breaker 26 and the start switch circuit 36 are in the on state, the second fuel cell FC2 is connected to the smoothing capacitor C7 and the second inverter 60a, and the second inverter 60a is DC Supply voltage. The second inverter 60a has output nodes N3 and N4 connected to both ends of the primary winding 71a of the second transformer 70a.

  The second inverter 60a converts the DC voltage supplied from the second fuel cell FC2 into an AC voltage and supplies it to the output nodes N3 and N4. For example, the second inverter 60a includes switching elements Q61 to Q64 and diodes D61 to D64 connected in parallel to the switching elements Q61 to Q64, respectively. In the example shown in FIG. 8, each of switching elements Q61 to Q64 is an IGBT.

  Switching elements Q61 and Q62 have collectors connected to the positive electrode terminal of second fuel cell FC2, emitters connected to output nodes N3 and N4 respectively, and gates to which respective control signals are supplied. There is. The diodes D61 and D62 have a cathode connected to the positive electrode terminal of the second fuel cell FC2 and an anode connected to the output nodes N3 and N4, respectively.

  Switching elements Q63 and Q64 have collectors respectively connected to output nodes N3 and N4, an emitter connected to the negative electrode terminal of second fuel cell FC2, and gates to which respective control signals are supplied. There is. The diodes D63 and D64 have cathodes connected to the output nodes N3 and N4, respectively, and an anode connected to the negative electrode terminal of the second fuel cell FC2.

  The switching elements Q61 to Q64 perform a switching operation in accordance with a control signal supplied to the gate from the control unit 120 via the control signal transmission unit 140. The waveforms of those control signals may be the same as the waveforms of the control signals shown in FIG. The second inverter 60a converts, for example, the DC voltage 700V supplied from the second fuel cell FC2 into an AC voltage, and supplies the AC voltage to the primary winding 71a of the second transformer 70a. The frequency of the alternating voltage is, for example, in the range of 200 Hz to 1 kHz, which is three or more times the frequency of the commercial power supply.

  The second transformer 70a has a primary winding 71a supplied with an AC voltage from the second inverter 60a, and a secondary winding 72a electrically isolated from the primary winding 71a. doing. Thereby, the second inverter 60a is electrically isolated from the ground line GL to which the second PWM converter 80b and the motor drive circuit 100 and the like are connected.

  The second PWM converter 80b converts the AC voltage supplied from the secondary winding 72a of the second transformer 70a into a DC link voltage (for example, 1500 V) and supplies it to the power supply line PL. For example, the second PWM converter 80b includes switching elements Q71 to Q74 and diodes D71 to D74 connected in parallel to the switching elements Q71 to Q74, respectively. In the example shown in FIG. 8, each of switching elements Q71 to Q74 is an IGBT.

  Switching elements Q71 and Q72 have collectors connected to power supply line PL, emitters connected to both ends of secondary side winding 72a of second transformer 70a, and gates to which respective control signals are supplied. have. The diodes D71 and D72 each have a cathode connected to the power supply line PL and an anode connected to both ends of the secondary winding 72a of the second transformer 70a.

  Switching elements Q73 and Q74 have collectors respectively connected to both ends of secondary side winding 72a of second transformer 70a, an emitter connected to ground line GL, and gates to which respective control signals are supplied. have. The diodes D73 and D74 have cathodes respectively connected to both ends of the secondary winding 72a of the second transformer 70a and an anode connected to the ground line GL.

  Switching elements Q71 to Q74 perform a switching operation in accordance with a control signal supplied from control unit 120 to the gate. The waveforms of those control signals may be the same as the waveforms of the control signals shown in FIG. The second PWM converter 80b converts the AC voltage supplied from the secondary winding 72a of the second transformer 70a into a DC link voltage and supplies the DC link voltage to the power supply line PL. The value of the DC link voltage can be controlled to a desired value by the period or duty ratio of the control signal supplied to the gates of switching elements Q71-Q74.

  In the power supply line PL, the DC link voltage supplied from the PWM converter 80a and the DC link voltage supplied from the second PWM converter 80b are synthesized. Therefore, control unit 120 responds to the output voltages of fuel cells FC1 and FC2 so that the DC link voltage supplied from PWM converter 80a and the DC link voltage supplied from second PWM converter 80b do not become unbalanced. Then, the cycle or duty ratio of the control signal supplied to the PWM converter 80a and the second PWM converter 80b is set. Therefore, a voltmeter for measuring the output voltage of the fuel cell FC1 and a voltmeter for measuring the output voltage of the fuel cell FC2 are provided in the electric vehicle.

  According to the third embodiment of the present invention, the inverter 60 is electrically isolated from the PWM converter 80a and the motor drive circuit 100, and the second inverter 60a is a second PWM converter 80b and the motor drive circuit 100. It is electrically isolated from Therefore, while the circuit directly connected to the fuel cells FC1 and FC2 is not grounded, it is possible to ground the motor drive circuit 100 etc. which is supplied with power from the fuel cells FC1 and FC2 or the overhead wire to drive the main motor 40. Become.

<Power conversion method>
Next, a power conversion method according to an embodiment of the present invention will be described with reference to FIGS. 1, 3 and 9. FIG. 9 is a flowchart showing a power conversion method according to an embodiment of the present invention.

  As shown in FIGS. 1 and 3, this power conversion method includes an inverter 60 for converting a DC voltage to an AC voltage, a primary side winding 71 to which an AC voltage is supplied from the inverter 60, and a primary side winding. A transformer 70 having a secondary winding 72 electrically isolated from the wire 71, and a voltage conversion circuit 80 generating a DC voltage based on an AC voltage supplied from the secondary winding 72 of the transformer 70. And a motor drive circuit 100 that generates a drive voltage of the main motor 40 based on the DC voltage supplied from the power supply line PL.

  In step S1 shown in FIG. 9, the control unit 120 sets the power conversion device to any one of the first mode to the third mode. The electric vehicle travels using the power supplied from the fuel cell FC1 in the first mode, and travels using the power supplied from the overhead wire in the second mode, and the storage battery BAT in the third mode. Drive using the power supplied from the

  Steps S2 to S5 shown in FIG. 9 represent the operation of the power conversion device (see FIG. 1) in the first mode. First, in step S2, the control unit 120 controls the switching circuit 90 to supply the DC voltage generated by the voltage conversion circuit 80 to the power supply line PL.

  Next, in step S3, the control unit 120 supplies a control signal to the inverter 60 electrically isolated from the grounded rail. As a result, the inverter 60 converts the DC voltage supplied from the fuel cell FC1 into an AC voltage and supplies it to the primary winding 71 of the transformer 70. Further, in step S4, a DC voltage is generated based on the AC voltage supplied from the secondary winding 72 of the transformer 70 using the voltage conversion circuit 80.

  Here, in step S4, using the plurality of bridge-connected diodes D21 to D24 that constitute the voltage conversion circuit 80, the AC voltage supplied from the secondary winding 72 of the transformer 70 is rectified to a DC voltage May be generated. Alternatively, when the PWM converter 80a shown in FIG. 6 is used, the control unit 120 converts the voltage conversion circuit into a DC voltage so as to convert the AC voltage supplied from the secondary winding 72 of the transformer 70. A control signal may be supplied to the PWM converter 80a to be configured.

  Next, in step S5, the control unit 120 supplies a control signal to the motor drive circuit 100 electrically connected to the grounded rail. Thereby, motor drive circuit 100 generates a drive voltage of main motor 40 based on the DC voltage supplied from power supply line PL. As a result, the electric vehicle travels using the power supplied from the fuel cell FC1.

  Steps S6 to S7 shown in FIG. 9 represent the operation of the power conversion device in the second mode (see FIG. 3). First, in step S6, the control unit 120 controls the switching circuit 90 to supply the DC voltage supplied from the input terminal 91 electrically connected to the overhead wire through the pantograph 10 to the power supply line PL.

  Next, in step S7, the control unit 120 supplies a control signal to the motor drive circuit 100 electrically connected to the grounded rail. Thereby, motor drive circuit 100 generates a drive voltage of main motor 40 based on the DC voltage supplied from power supply line PL. As a result, the electric vehicle travels using the power supplied from the overhead line.

  Steps S8 to S10 shown in FIG. 9 represent the operation of the power conversion device in the third mode. First, in step S8, the control unit 120 controls the switching circuit 90 in the non-connected state. Alternatively, the control unit 120 may turn off the high speed circuit breaker 22.

  Next, in step S9, the control unit 120 supplies a control signal to the DC / DC converter 110. Thereby, DC / DC converter 110 boosts the DC voltage output from storage battery BAT and supplies it to power supply line PL.

  Next, in step S10, the control unit 120 supplies a control signal to the motor drive circuit 100 electrically connected to the grounded rail. Thereby, motor drive circuit 100 generates a drive voltage of main motor 40 based on the DC voltage supplied from power supply line PL. As a result, the electric vehicle travels using the power supplied from the storage battery BAT.

  According to the present embodiment, in the first mode, the inverter 60 electrically isolated from the grounded rail is used to convert the DC voltage supplied from the fuel cell FC1 into an AC voltage to convert the transformer 70. The voltage is supplied to the primary side winding 71, and a DC voltage is generated based on the AC voltage supplied from the secondary side winding 72 of the transformer 70 using the voltage conversion circuit 80 and supplied to the power supply line PL. The circuit directly connected to the fuel cell FC1 can be ungrounded. In the first to third modes, motor drive circuit 100 or the like that generates the drive voltage of main motor 40 can be grounded based on the DC voltage supplied from power supply line PL.

  The present invention is not limited to the embodiments described above, and many modifications can be made within the technical concept of the present invention by those skilled in the art. For example, it is also possible to combine and implement a plurality of embodiments selected from the embodiments described above.

  The present invention can be used in a power converter used in an electric vehicle such as a railway vehicle or in an electric vehicle equipped with such a power converter.

  DESCRIPTION OF SYMBOLS 10 ... Pantograph, 12 ... Wheel, 13 ... Switch circuit for grounding, 21-26 ... High-speed circuit breaker, 31-36 ... Switch circuit for starting, 40 ... Main motor, 50 ... Power supply device for auxiliary circuits, 60, 60a ... Inverter, 70, 70a: Transformer, 71, 71a: Primary side winding, 72, 72a: Secondary side winding, 80: Voltage conversion circuit, 80a, 80b: PWM converter, 90: Switching circuit, 91: Input Terminals 100 Motor driving circuit 110 DC / DC converter 120 Control unit 130 Storage unit 140 Control signal transmission unit FC1 and FC2 Fuel cell BAT BAT BATTERY Battery R1 to R7 Resistance C1 ~ C7 ... capacitor, L4 to L6 ... inductor, Q11 to Q74 ... switching element, D11 to D74 ... diode

Claims (12)

An inverter for converting a DC voltage supplied from a fuel cell into an AC voltage;
A transformer having a primary side winding to which alternating voltage is supplied from the inverter, and a secondary side winding electrically isolated from the primary side winding;
A voltage conversion circuit that generates a DC voltage based on an AC voltage supplied from a secondary winding of the transformer;
A switching circuit that supplies at least a DC voltage supplied from the voltage conversion circuit to a power supply line in a first mode, and supplies a DC voltage supplied from an input terminal to the power supply line in a second mode;
A motor drive circuit that generates a drive voltage of a main motor based on a DC voltage supplied from the power supply line;
A power converter, the inverter being electrically isolated from the voltage conversion circuit and the motor drive circuit.   The power conversion device according to claim 1, wherein the voltage conversion circuit includes a plurality of bridge-connected diodes that rectify an AC voltage supplied from a secondary winding of the transformer to generate a DC voltage.   The power conversion device according to claim 2, further comprising: a capacitor connected between an output node of said inverter and a primary side winding of said transformer to form a series resonant circuit with an inductance component of said transformer.   The power conversion device according to claim 1, wherein the voltage conversion circuit includes a PWM converter that converts an AC voltage supplied from a secondary winding of the transformer into a DC voltage. A second inverter for converting DC voltage supplied from the second fuel cell into AC voltage;
A second transformer having a primary side winding to which alternating voltage is supplied from the second inverter, and a secondary side winding electrically isolated from the primary side winding;
A second PWM converter for converting an AC voltage supplied from a secondary winding of the second transformer into a DC voltage;
And the second inverter is electrically isolated from the second PWM converter and the motor drive circuit, and the DC voltage output from the PWM converter and the second inverter output The power converter according to claim 4, wherein the DC voltage is combined with the DC voltage.   The DC / DC converter according to any one of claims 1 to 5, further comprising: a DC / DC converter for stepping down a DC voltage of the power supply line to charge a storage battery, or boosting a DC voltage output from the storage battery to supply to the power supply line. The power converter according to any one of the preceding items.   When the DC voltage of the input terminal is equal to or less than a predetermined threshold, the power converter is set to the first mode, and when the DC voltage of the input terminal is larger than a predetermined threshold, the power converter The power converter according to any one of claims 1 to 6, further comprising: a controller configured to set the second mode to the second mode. The power converter according to any one of claims 1 to 7,
A plurality of wheels rotatably mounted on a vehicle body on which the power conversion device is installed;
An electric vehicle, the inverter being electrically isolated from the plurality of wheels.   The electric vehicle according to claim 8, further comprising a switch circuit electrically connecting the voltage conversion circuit and the motor drive circuit to the plurality of wheels when turned on. A transformer having an inverter for converting a DC voltage to an AC voltage, a primary side winding to which an AC voltage is supplied from the inverter, and a secondary side winding electrically isolated from the primary side winding; A voltage conversion circuit that generates a DC voltage based on an AC voltage supplied from a secondary winding of the transformer, and a motor drive that generates a drive voltage of a main motor based on a DC voltage supplied from a power supply line A power conversion method used in a power conversion device including a circuit;
Controlling a switching circuit to supply a DC voltage generated by the voltage conversion circuit to the power supply line in a first mode;
In the first mode, by supplying a control signal to the inverter electrically isolated from the grounded rail, the DC voltage supplied from the fuel cell is converted to an AC voltage to be the primary of the transformer. Supplying the side winding (b);
Generating, in the first mode, a DC voltage based on an AC voltage supplied from a secondary winding of the transformer using the voltage conversion circuit;
In the first mode, by supplying a control signal to the motor drive circuit electrically connected to the grounded rail, the drive voltage of the main motor is determined based on the DC voltage supplied from the power supply line. Generating step (d),
Controlling the switching circuit to supply a DC voltage supplied from an input terminal to the power supply line in a second mode;
In the second mode, by supplying a control signal to the motor drive circuit electrically connected to the grounded rail, the drive voltage of the main motor is determined based on the DC voltage supplied from the power supply line. Generating step (f),
Power conversion method.   Step (c) rectifies an alternating voltage supplied from a secondary winding of the transformer using a plurality of bridge-connected diodes constituting the voltage conversion circuit to generate a direct voltage The power conversion method according to claim 10, comprising.   The step (c) includes supplying a control signal to a PWM converter constituting the voltage conversion circuit so as to convert an alternating voltage supplied from a secondary winding of the transformer into a direct voltage. The power conversion method according to Item 10.

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