JP2009291023A - Hybrid power supply and power unit using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply device which outputs a low-current, high-voltage electric energy while suppressing a loss caused by Joule heat, in order to constitute a high-output and high-efficiency electric system, and which is configured to connect a plurality of power supplies in series as a means for increasing output voltage without using a booster circuit, and which increases the output of the power supplies while keeping small the capacity of the power supplies. <P>SOLUTION: Provided is a hybrid power supply which includes a first power supply having a monotonously decreasing voltage characteristic with respect to a required current and a second power supply having a monotonously increasing voltage characteristic with respect to the required current, which are electrically connected in series, to ensure a high output voltage and a high energy efficiency. Also provided is a power unit using the hybrid power supply. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a hybrid power source that is suitably used as a distributed power source and supplies power to an electric load including a moving body such as an automobile, and a power unit having the hybrid power source.

  When supplying electrical energy to a load with high efficiency, if the power supply voltage is used at a high voltage, Joule heat generated by the current can be reduced, and the utilization efficiency of electrical energy can be improved. For example, in the case of a motor, it is well known that when the rated voltage is increased, the drive current can be reduced and the efficiency is greatly improved. Further, if the current is reduced, the coil inside the motor can be made thinner, which is effective in reducing the size of the motor. In order to increase the power supply voltage for the above purpose, Patent Document 1, Patent Document 2, and Patent Document 3 disclose a configuration in which a low voltage is boosted by a booster circuit after electric energy is generated to obtain a high voltage.

JP 2006-248814 A JP 2007-245999 A JP 2002-231287 A

  However, use of a booster circuit causes energy loss in the circuit itself, so that a significant boost is not a good measure for reducing the loss. Further, when the output of the power supply is increased as a means for boosting the power supply voltage without using the booster circuit, the capacity of the power supply increases and the power supply becomes large. In addition, when a plurality of power supplies are connected in series to increase the voltage, the voltage fluctuation increases when the electric load varies due to the internal resistance. In general, when designing a power supply, it is designed so that there is no hindrance to the operation even at the worst value of voltage fluctuation, so in most cases it will be operated below the effective maximum capacity of the power supply. It has become an issue. For example, when a fuel cell is used as a power source, double the voltage can be supplied by connecting two fuel cells with half capacity in series, but the voltage decreases at the maximum load because the voltage decreases as the load current increases. Must be used as a design value, and it is difficult to make the power supply voltage sufficiently high.

  An object of the present invention is to provide a hybrid power supply capable of generating a stable high voltage against load fluctuations. Another object of the present invention is to provide a power unit having the above hybrid power source and a moving body equipped with the power unit.

  In order to solve the above problems, the present invention electrically connects a first power source having a characteristic that the voltage monotonously decreases with respect to the required current and a second power source having a characteristic that the voltage monotonously increases with respect to the required current. A hybrid power supply characterized by being connected in series and a system using the hybrid power supply are provided.

  The hybrid power source includes a positive side output terminal, a negative side output terminal, and a connection point voltage output terminal that outputs a connection point voltage of the first power source and the second power source, and the positive side output terminal and the negative side output terminal The potential difference is the sum of the voltages of the power supplies constituting the hybrid power supply.

In the hybrid power supply, a hybrid power supply is provided in which a storage unit is connected between the positive output terminal and the negative output terminal.
In the hybrid power supply, a hybrid power supply is provided in which positive output terminals of the first power supply and the second power supply are connected to respective negative output terminals via switches 1 and 2.

  A power device having the hybrid power source, wherein the hybrid system has an electric motor that converts electric power generated from the hybrid power source into mechanical power, and the electric motor converts mechanical power received by an external load into electric energy, When receiving mechanical power from an external load, the hybrid power source electrically connects the motor and the second power source in series.

  A power unit having an engine, a generator for generating power with the power of the engine, and a fuel cell, the power unit having a reactor for recovering exhaust heat of the engine and supplying fuel for power generation of the fuel cell, 2. The power generation unit according to claim 1, wherein the power generation unit uses the fuel for power generation from the reactor to generate power, and the power unit uses the fuel cell as the first power source according to claim 1. Provided is a power unit comprising the hybrid power source as the second power source. Moreover, the mobile body which has the said power unit is provided.

  According to the present invention, a high-voltage hybrid power supply with little energy loss can be realized without using a booster circuit. Moreover, the energy efficiency of the power unit using the hybrid power source or a moving body equipped with the power unit can be improved. Furthermore, even in a power supply with a large load fluctuation, a sufficient output voltage can be obtained and electric energy can be supplied with high efficiency.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a configuration diagram of a hybrid power source in which a first power source having a voltage characteristic monotonously decreasing with respect to a load current and a second power source having a monotonically increasing voltage characteristic are electrically connected in series. The hybrid power source includes a first power source 1 and a second power source 2 connected in series. The positive output terminal 4 of the first power supply 1 is connected to the positive output terminal 8 of the hybrid power supply, the negative output terminal 5 of the first power supply 1 is connected to the positive output 6 of the second power supply 2, and the second power supply. The second negative output terminal 7 is connected to the negative output terminal 9 of the hybrid power supply.

  The hybrid power supply voltage between the positive output terminal 8 and the negative output terminal 9 is the sum of the voltages of the first power supply 1 and the second power supply 2 connected in series. Further, the positive output terminal 8 is connected to the positive input terminal 10 of the load 3, and the negative output terminal 9 is connected to the negative input terminal 11 of the load to constitute a power supply circuit. Therefore, the input voltage of the load 3 becomes a hybrid power supply voltage between the positive output terminal 8 and the negative output terminal 9. Since the first power supply 1, the second power supply 2 and the load 3 are connected in series, the current in the power supply circuit is the same I. Therefore, the voltage V of the load 3 is the sum of V1 and V2, and the current I of the load 3 is the same as the current of each electric energy supply source. The input power VI of the load is the sum of V1 × I and V2 × I.

  As shown in FIG. 2, the voltage-current characteristics of each power supply require that the voltage-current characteristics of each power supply have a monotonically decreasing characteristic and a monotonically increasing characteristic in order to keep the load voltage constant. By this adjustment, the overall output voltage is set to a high voltage, a stable output voltage is supplied to the load, and the electric energy generated from the power supply can be efficiently supplied to the load. That is, the loss of the booster circuit is eliminated and the power transmission efficiency of the entire power supply circuit is improved.

  In addition, since the booster circuit and the voltage stabilizing circuit are not used and the output of each power supply is half of the same output, each power supply can be reduced in size and cost.

  The hybrid power source of this embodiment is composed of a first power source 1 and a second power source 2 connected in series, and the current flowing through each power source is the same. Therefore, in order to realize a stable output voltage, the output voltage characteristic of the power supply due to the output current fluctuation is important. For example, when the first power source and the second power source are configured by connecting a fuel cell and a generator in series, as shown in FIG. 3, when the load current increases, the voltage of the fuel cell decreases. On the other hand, as shown in FIG. 4, when the load current increases, the generator can increase the number of rotations to increase the voltage. Therefore, when viewed from the total output of the fuel cell and the generator, it is possible to output to the load with a stable voltage. The generator is generally a DC generator or an AC generator with an inverter, but may be an induction machine or an SRM.

  FIG. 5 shows a power supply circuit according to a second embodiment in which a power storage device is connected to the hybrid power supply circuit. A power supply circuit is configured in which a power storage device 12 is connected between the positive output terminal 8 and the negative output terminal 9 of the hybrid power supply. The power storage device 12 may have any form as long as it has a function of storing and discharging electrical energy, such as an electric double layer capacitor, a battery, a flywheel, a superconducting coil, a pressure accumulator, and the like. . Furthermore, any of these may be used alone or in combination of a plurality of them.

  FIG. 6 shows a power supply circuit according to the third embodiment. 6 shows that the switch 13 is provided between the positive output terminal 4 and the negative output terminal 5 of the first power supply 1 and the switch 14 is the positive output terminal 6 of the second power supply 2 in the power supply circuit shown in FIG. And a power supply circuit connected between the negative output terminal 7 and FIG. When power is supplied to the load 3, if any power supply in the series power supply circuit fails, the failure power supply is shut off from the power supply circuit by closing a switch connected in parallel to the failed power supply. It is possible to supply electric energy to the load 3 without interrupting the power supply. For example, when the second power supply 2 fails, the switch 14 connected in parallel thereto is closed and the switch 15 is opened.

  It is also possible to apply the above-described hybrid power source to a power unit, and its configuration is shown in FIG. In this power unit, a switch 17 is further connected between the negative output terminal 5 of the first power supply 1 and the positive output terminal 6 of the second power supply 2 on the power supply circuit shown in FIG. The negative output terminal 9 and the negative input terminal 11 of the motor 16 are connected, and the switch 19 is connected between the positive output terminal 6 and the negative input terminal 11 of the motor 16.

  As shown in FIG. 7A, when traveling, when the switch 17 is closed, the switch 18 is closed, and the switch 19 is opened, the electrical energy is transferred from the power storage device 12, the first power source 1, and the second power source 2 to the motor 16. It is possible to drive the moving body and further increase the efficiency of regenerative electric energy utilization.

  The motor 16 during traveling operates as a generator during deceleration, but it has been difficult to recover the low-voltage, large-current regenerative electric energy generated from the motor 16 with high efficiency. However, as shown in FIG. 7B, when the switch 17 is opened, the switch 18 is opened, and the switch 19 is closed during deceleration, the low voltage and large current electrical energy generated from the motor 16 is controlled. The voltage can be increased by connecting the power supply 2 in series, and energy can be efficiently recovered in the power storage device 12. The second power source 2 connected in series according to the change in the regenerative voltage generated from the motor 16 can be adjusted between 0 V and the maximum voltage of the power storage device, and is preferably compatible with a large current.

  The present invention further provides Example 5 using the hybrid power source and the power source circuit as the power unit shown in FIG. The power unit of the present embodiment includes an engine 20, a generator 21 that generates power using engine power, and a reactor 22 that recovers exhaust heat of the engine 20 and supplies fuel cell power generation fuel to a fuel cell 23. The battery 23 is a first power source and the generator 21 is a second power source. The generated voltage is increased by connecting the generator 21 and the fuel cell 23 in series. When a generator and a fuel cell are connected in series, the voltage of the fuel cell decreases when the load current increases as shown in FIG. 3, whereas the generator increases the rotational speed when the load current increases as shown in FIG. Since it is possible to increase the voltage, it is possible to supply power to the load with a stable voltage when viewed from the total output of the generator and the fuel cell.

  Further, this power unit can improve the system efficiency of the power unit by mainly using the fuel cell 23 at the time of low load and mainly using the generator 21 at the time of high load. Further, the generator 21 and the fuel cell 23 are connected in series, so that a high output voltage can be generated with half the output, and electric energy can be efficiently supplied to the motor 16 without using a booster circuit. This can be realized by closing the switch 17, closing the switch 18, and opening the switch 19 as shown in FIG. As a result, the capacity of each component is small and can be reduced in size, so that the system efficiency can be greatly improved.

  Further, at the time of deceleration, as shown in FIG. 8B, in order to efficiently recover the regenerative electric energy of the motor 16, the switch 17 is opened, the switch 18 is opened, and the switch 19 is closed. The regenerative electric energy and the electric energy of the generator 21 are boosted by being connected in series, and the electric energy can be stored in the power storage device 12 smoothly. This power unit is suitable for being mounted on a moving body such as an automobile, and can be applied as a distributed power source.

  In the present invention, in the hybrid system of the engine, the generator, the reactor, and the fuel cell, the engine and the fuel cell can use one kind or many kinds of fuels. For example, gasoline, natural gas, ethanol, biofuel, organic hydride and the like are used as engine fuel. Further, hydrogen, C0, natural gas, ethanol, methanol, organic hydride, or the like is used as the power generation fuel of the fuel cell.

  In the present embodiment, as shown in FIG. 9, a control device for a power unit is disclosed in which the fuel cell 23 is the power source 1 and the generator 21 is the power source 2. First, the case where electric energy is supplied to the motor in this embodiment will be described. In this case, the switch 17 is closed, the switch 18 is closed, and the switch 19 is open. The fuel cell 23 and the DC generator 21 are electrically connected in series, the power generation hydrogen of the fuel cell 23 is supplied by the hydrogen supply device 25, and the power of the DC generator 21 is supplied by the power supply device 26. . The generated electrical energy is supplied to the capacitor 12 or the motor / generator 29 which is a power storage device. The current in the electric circuit is detected by the first current sensor 27 and the second current sensor 28, and state signals such as voltage and current of each component are measured and processed by the control device 24. Control the entire system.

  FIG. 10 is a flowchart for explaining the power supply control of the control device 24. First, when the processing is started, the control device 24 detects an output from the first current sensor 27 in FIG. If there is a current change amount, the process proceeds to step ST2 to determine whether the current increases or decreases. When the current increases, the process proceeds to step ST3, the amount of hydrogen supplied to the fuel cell 23 is increased in accordance with the current value, and the current value of the fuel cell reaches the target current.

  In step ST4, the rotational speed of the generator 21 electrically connected in series with the fuel cell 23 is increased, and the output voltage of the generator is increased by increasing the rotational speed at the same current as shown in the characteristic diagram of FIG. increase. Then, the process proceeds from step ST4 to ST5, and it is determined whether the sum of the fuel cell voltage and the generator voltage can satisfy the motor drive voltage. If not satisfied, the process returns to step ST4 again, and the circulation process is performed until the voltage satisfies the condition of ST5. When step ST5 ends, control is transferred to the main routine in step ST9. On the other hand, when the current decreases, the process proceeds to step ST6, the amount of hydrogen supplied to the fuel cell 23 is decreased in accordance with the current value, and the current value of the fuel cell reaches the target current. In step ST7, the rotational speed of the generator 21 electrically connected in series with the fuel cell 23 is lowered, and the output voltage of the generator is lowered by lowering the rotational speed at the same current as shown in FIG. Then, the process proceeds from step ST7 to ST8, and it is determined whether the sum of the fuel cell voltage and the generator voltage can satisfy the motor drive voltage. If not satisfied, the process returns to step ST7 and the circulation process is performed until the voltage satisfies the condition of ST8. When step ST8 ends, control is transferred to the main routine in step ST9.

  From the above results, it was confirmed that it was possible to supply a stable and high voltage output by the fuel cell and the generator according to the fluctuation of the motor. A high-voltage power supply with little loss could be made without using a booster circuit. The efficiency of the power unit and the moving body using this power source can be improved. Furthermore, electric energy can be supplied with a sufficient output voltage and high efficiency even in a power supply having a large load fluctuation. In particular, since the mobile body has a large load fluctuation, the present invention is an ideal mounting target.

  Next, in the sixth embodiment, a case where electric energy is collected from the motor / generator and stored in the capacitor 12 will be described. In this case, the switch 17 is open, the switch 18 is open, and the switch 19 is closed.

  FIG. 11 is a flowchart for explaining the power regeneration control of the control device 24. First, when the process is started, the control device 24 detects the output voltage of the motor / generator 29 of FIG. 9 in step ST10 and determines whether the charging voltage of the capacitor of the power storage device is satisfied. If satisfied, the process proceeds to step ST11. When the switch 14 is closed and step ST11 ends, control is transferred to the main routine in step ST14. On the other hand, if the output voltage of the motor / generator 29 is not satisfied with the charging voltage of the capacitor 12, the process proceeds to step ST12, and the sum of the output voltage of the motor / generator 30 and the output voltage of the generator 21 is the charging voltage of the capacitor. Is satisfied. If not satisfied, the circulation process is performed until the voltage satisfies the condition of ST12 by increasing the rotational speed of the generator in step ST13. When step ST12 ends, control is transferred to the main routine in step ST14.

  From the above results, it is possible to increase the voltage by connecting the low voltage, large current electric energy generated from the motor / generator 29 during deceleration with the controlled generator 21 in series, thereby efficiently storing power. It was confirmed that it could be collected in the device. Further improvement in utilization efficiency of electric energy of the power unit and the moving body can be expected.

  The present embodiment shows an example in which a storage battery is used instead of the capacitor of the power storage device that recovers the electric energy of the motor / generator 29 in the sixth embodiment. As a result of carrying out in the same manner as in Example 6, it was confirmed that the recovery rate of regenerative electric energy decreased due to the limitation of the charging current of the storage battery compared with the capacitor during the regeneration of electric energy. Furthermore, a power storage device such as a capacitor is preferable in order to temporarily store electric energy in consideration of charge / discharge efficiency and weight.

  The present embodiment is an example of a power unit using a solar cell as a first power source and a generator as a second power source instead of the fuel cell of the sixth embodiment. Stable and high voltage power could be supplied to the load motor by controlling the rotational speed of the generators in series according to the output fluctuation of the solar cell. In order to stably supply power to a power source affected by an external environment and load fluctuation such as a solar cell, it is necessary to make a hybrid with a power source having different output voltage characteristics with respect to the load fluctuation.

The present embodiment is an example of a power unit that uses a solar cell as the first power source and a gas turbine as the second power source instead of the generator of the eighth embodiment. As in Example 8, it was confirmed that the output voltage from the hybrid power source was supplied stably and at a high voltage by controlling the rotational speed of the gas turbine in accordance with the output fluctuation of the solar cell.
[Comparative Example 1]

  In this comparative example, as shown in FIG. 12, the fuel cell 30 is a power unit having the first power source and the fuel cell 31 is the second power source. Hydrogen is supplied to the fuel cell from a high-pressure hydrogen cylinder 32. This is an example of generating electric power and supplying electric energy to a motor.

In this comparative example, when the load motor fluctuates, the current-voltage characteristics of the fuel cell 30 and the fuel cell 31 are the same as shown in FIG. Only one fuel cell cannot supply stable electric power to the motor in response to load fluctuations.
[Comparative Example 2]

In this comparative example, as shown in FIG. 13, a power device having a generator 33 as the first power source and a generator 34 as the second power source, and the generator generates power using the power source of the engine 20. This is an example of supplying electric energy to the motor 3.

  In this comparative example, when the load motor fluctuates, as shown in FIG. 4, the current-voltage characteristics of the generator 33 and the generator 34 are the same, and the motive energy source is the same engine. Stable power cannot be supplied to the motor in response to a load change with only two fuel cells without using a booster or voltage stabilization circuit. In the case where the generator 33 and the generator 34 are driven by respective power sources, stable power can be supplied by controlling the number of revolutions of the generator according to load fluctuations. From the viewpoint of control, it is not suitable for a power unit or a moving body.

  Although the present invention has been described with respect to the embodiment in which the fuel cell is the first power source and the generator is the second power source, the present invention is not limited to this configuration. For example, the first power source may be a wind power generator, and the second power source may be applied as an engine, a nuclear power generation power source, or a combination of these power sources.

  It should be thought that the form of the Example disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be applied to a hybrid power source that supplies electric energy used for a distributed power source including a moving body such as an automobile and a system using the hybrid power source. In particular, the mobile body is an ideal mounting target of the present invention because of a large load fluctuation.

It is a circuit diagram of the hybrid power supply of the Example of this invention. It is an output voltage-current characteristic view of the 1st power supply of the present invention example, and the 2nd power supply. It is an output voltage-current characteristic view of a fuel cell. It is a characteristic view which shows the influence of the output voltage and electric current by the rotation speed of a generator. It is a circuit diagram of the hybrid power supply which has the electrical storage apparatus of this invention Example. It is a circuit diagram of the hybrid power supply which has a switch of the example of the present invention. It is a circuit diagram showing a power unit of an embodiment of the present invention. It is a circuit diagram of the power plant which has the generator of this invention Example and a fuel cell. It is a block diagram which shows the control structure by a control apparatus. It is a flowchart for demonstrating the electric power supply control of a control apparatus. It is a flowchart for demonstrating the electric power regeneration control of a control apparatus. 6 is a schematic diagram showing a configuration of Comparative Example 1. FIG. 6 is a schematic diagram showing a configuration of Comparative Example 2. FIG.

Explanation of symbols

  1: First power source 1, 2: Second power source 2, 3: Load, 12: Power storage device, 13: Switch, 14: Switch, 16: Motor, 20: Engine, 21: Generator, 22: Reactor, 23: Fuel cell, 24: control device, 25: hydrogen supply device, 26: power supply device

Claims (8)

  A hybrid power source, wherein a first power source having a monotonically decreasing voltage characteristic with respect to a load current and a second power source having a monotonically increasing voltage characteristic with respect to the load current are electrically connected in series.   The hybrid power supply according to claim 1, wherein a positive output terminal and a negative output terminal of the hybrid power supply having a first power supply and a second power supply, and a junction voltage output terminal intermediate between the first power supply and the second power supply. And a potential difference between the positive output terminal and the negative output terminal is a sum of voltages of a first power supply and a second power supply constituting the hybrid power supply.   3. The hybrid power source according to claim 1, wherein a fuel cell is used as the first power source and a generator is used as the second power source.   3. The hybrid power supply according to claim 2, wherein a power storage means is connected between the positive output terminal and the negative output terminal.   3. The hybrid power supply according to claim 2, wherein the first power supply and the second power supply have switching means for cutting off each power supply connected in parallel from the hybrid power supply.   6. A power plant having a hybrid power source according to claim 1, wherein the power plant has an electric motor for converting electric power generated from the hybrid power source into mechanical power, and the electric motor is received by an external load. A power device comprising: switching means for converting the mechanical power into electrical energy, and the hybrid power source electrically connecting the electric motor and the second power source in series when mechanical power is received from an external load.   7. The power unit according to claim 6, wherein the hybrid power source of the power unit includes a fuel cell as a first power source and a generator as a second power source, an engine that drives the generator, and exhaust heat of the engine is recovered and fuel is recovered. A power unit comprising a reactor for supplying battery power generation fuel, wherein the fuel cell generates power using fuel cell power generation fuel generated from the reactor.   A moving body comprising the power unit according to claim 6.

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