Kinetic Energy Storage Device

Abstract

To provide a kinetic energy storage device capable of reducing loss.SOLUTION: A flywheel 12 has a rotor 62 mechanically connected to a rotator 131 of a motor generator 13, a journal bearing 63 and a pivot bearing 64 rotatably supporting the rotor 62, and a case 66. The rotor 62 has a high magnetic area 622 with a first magnetism degree and a low magnetic area 621 whose magnetism degree is lower than that of a first area at different positions in a vertical direction that is a rotation axis direction of the rotor 62.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a kinetic energy storage device. [Background technology]

[0002] In recent years, electric vehicles equipped with large-capacity batteries have been developed. Although these electric vehicles have a long driving range, they have a problem of taking a long time to charge, so development of rapid charging is underway.

[0003] To realize rapid charging, if high voltage electricity (for example, 6600V) is drawn from a commercial power source, a high voltage receiving facility (cubicle) is required, which is a large burden in terms of size and cost. Also, if it is attempted to store the same amount of energy as an existing gas station, the required land area would be extremely large, which is not realistic.

[0004] Therefore, Patent Document 1 proposes using a flywheel as an energy storage device to store kinetic energy instead of electrical energy. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Utility Model Application Publication No. 61-43735 Summary of the Invention [Problem to be solved by the invention]

[0006] However, there is room for improvement when attempting to commercially utilize the device described in Patent Document 1. In particular, if the loss in the flywheel is large, the energy efficiency deteriorates.

[0007] The present invention provides a kinetic energy storage device that can reduce losses. [Means for solving the problem]

[0008] The present invention relates to a rotor that is mechanically connected to a rotor of a rotating electric machine; A kinetic energy storage device comprising: The rotating body is provided at different positions in the rotation axis direction of the rotating body. A first region having a first degree of magnetism and a second region having a lower degree of magnetism than the first region. In one body Yes. Effect of the Invention

[0009] According to the present invention, a kinetic energy storage device capable of reducing losses can be provided. [Brief description of the drawings]

[0010] [Figure 1] 1 is a functional block diagram of a charging system 10 according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is an electric circuit diagram of the inverter 11 of FIG. [Diagram 3] 2 is an electrical circuit diagram of the quick charger 14 of FIG. 1. [Figure 4] 2 is a graph showing the change in charging power and the kinetic energy loading rate of the flywheel 12 over time in the charging system 10 of FIG. 1. [Diagram 5] FIG. 2 is a perspective view showing the flywheel 12 of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of a charging system of the present invention will be described with reference to the drawings.

[0012] [Charging system] 1, the charging system 10 is a charging system that charges a battery BAT mounted on a vehicle V, which is a moving body. The vehicle V may be any vehicle equipped with a battery BAT, such as a hybrid vehicle, a plug-in hybrid vehicle, an electric vehicle, or a fuel cell vehicle.

[0013] The charging system 10 includes an inverter 11 that converts power supplied from a commercial power source PS, a flywheel 12 that stores kinetic energy, a motor generator 13 electrically connected to the inverter 11 and mechanically connected to the flywheel 12, a quick charger 14 electrically connected to the motor generator 13 and supplies power to a battery BAT of the vehicle V, and a control device 16 that controls the inverter 11 and the quick charger 14. The flywheel 12 and the motor generator 13 constitute a kinetic energy storage unit 15.

[0014] The voltage of the power supplied from the commercial power source PS (hereinafter referred to as the input power) is preferably an AC voltage of 100V or more and 500V or less, for example, AC 200V in a three-phase three-wire system. If the voltage of the input power is high, a dedicated power receiving facility such as a high-voltage power receiving facility (cubicle) is required, but if the voltage of the input power is low, a special power receiving facility such as a high-voltage power receiving facility (cubicle) is not required. In addition, if the voltage of the input power is low, a large site for installing the high-voltage power receiving facility (cubicle) is not required, and the introduction cost can be reduced. Note that, if there is sufficient site space, a high-voltage power receiving facility (cubicle) capable of receiving an AC voltage of 6600V and a power of 100kW to 500kW may be installed.

[0015] 2, the inverter 11 includes a first inverter unit INV1 that converts three-phase AC power (hereinafter sometimes referred to as first three-phase AC power) that is the input power into DC power, and a second inverter unit INV2 that converts the DC power converted by the first inverter unit INV1 into three-phase AC power (hereinafter sometimes referred to as second three-phase AC power) that is different from the first three-phase AC power and is suitable for driving the motor generator 13. The first inverter unit INV1 and the second inverter unit INV2 have the same structure and are connected in series with a first smoothing capacitor 21 in between.

[0016] Each of the first inverter section INV1 and the second inverter section INV2 includes a bridge circuit formed by a plurality of switching elements that are bridge-connected. For example, the switching elements are transistors such as IGBTs (Insulated Gate Bipolar Transistors) or MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). For example, in the bridge circuit, a pair of high-side arm and low-side arm U-phase transistors UH, UL, a pair of high-side arm and low-side arm V-phase transistors VH, VL, and a pair of high-side arm and low-side arm W-phase transistors WH, WL are each bridge-connected.

[0017] The collectors of the high-side arm transistors UH, VH, and WH are connected to a positive terminal PI to form a high-side arm. In each phase, the positive terminals PI of the high-side arms are connected to a positive connection line 50p.

[0018] The emitters of the low-side arm transistors UL, VL, and WL are connected to a negative terminal NI to form a low-side arm. In each phase, the negative terminals NI of the low-side arms are connected to a negative connection line 50n.

[0019] In each phase, the emitters of the transistors UH, VH, WH of the high-side arm are connected to the collectors of the transistors UL, VL, WL of the low-side arm at a connection point T1.

[0020] The connection point T1 in each phase of the first inverter section INV1 is connected to the commercial power supply PS by a first connection line 51. The connection point T1 in each phase of the second inverter section INV2 is connected to the motor generator 13 by a second connection line 52.

[0021] The bridge circuit includes diodes connected in the forward direction from the emitter to the collector between the collector and emitter of each of the transistors UH, UL, VH, VL, WH, and WL.

[0022] Each of the first inverter unit INV1 and the second inverter unit INV2 switches the transistor pairs of each phase on (conducting) / off (blocking) based on a gate signal, which is a switching command input to the gate of each of the transistors UH, VH, WH, UL, VL, and WL. The first inverter unit INV1 converts first three-phase AC power input from the commercial power source PS into DC power, and the second inverter unit INV2 converts the DC power input from the first inverter unit INV1 into second three-phase AC power.

[0023] The first smoothing capacitor 21 smoothes out voltage fluctuations that occur with the on / off switching operations of the transistors UH, UL, VH, VL, WH, and WL of the first inverter section INV1 and the second inverter section INV2.

[0024] The motor generator 13 is a three-phase AC motor generator. When charging with energy, the motor generator 13 rotates the flywheel 12 by using the power input from the inverter 11 to perform power running. When charging the battery, the motor generator 13 performs regenerative running to convert the kinetic energy of the flywheel 12 into electrical energy, and supplies the power to the quick charger 14.

[0025] As shown in Fig. 3, the quick charger 14 includes a third inverter unit INV3 that converts three-phase AC power generated by the motor generator 13 into DC power, a fourth inverter unit INV4 that converts the DC power converted by the third inverter unit INV3 into single-phase AC power, a high-frequency transformer 31 that transforms the single-phase AC power input from the fourth inverter unit INV4, and a fifth inverter unit INV5 that converts the single-phase AC power input from the high-frequency transformer 31 into DC power. A second smoothing capacitor 32 is provided between the third inverter unit INV3 and the fourth inverter unit INV4, and a third smoothing capacitor 33 is provided downstream of the fifth inverter unit INV5. The fourth inverter unit INV4, the high-frequency transformer 31, and the fifth inverter unit INV5 constitute a boost converter 17 that boosts the power supplied from the motor generator 13 when charging the battery. The quick charger 14 may also include a matrix converter instead of the third inverter unit INV3 and the fourth inverter unit INV4.

[0026] The control device 16 performs switching control of the first inverter section INV1 and the second inverter section INV2 of the inverter 11, and switching control of the third inverter section INV3, the fourth inverter section INV4, and the fifth inverter section INV5 of the rapid charger 14, thereby charging the flywheel 12 with energy and charging the battery BAT installed in the vehicle V.

[0027] The charging system 10 configured in this manner may be installed in car dealerships, convenience stores, supermarkets, and the like. The flywheel 12 accumulates kinetic energy until the flywheel 12 is fully charged by being driven by the motor generator 13 that receives power supplied from the commercial power source PS via the inverter 11. The charging system 10 having the flywheel 12 that is fully charged may be recognized by a user (driver) of the vehicle V through a car navigation system or a mobile terminal such as a smartphone. Two charging systems 10 may be provided in one charging station, or three or more charging systems 10 may be provided. When the user needs to charge the vehicle V, the user can stop by any of the nearby charging systems 10 that are fully charged, thereby charging the battery BAT mounted on the vehicle V. This shortens or eliminates waiting time.

[0028] Each charging system 10 only needs to be able to supply the energy required to charge the battery BAT of one vehicle. Here, the vehicle V is assumed to be an electric vehicle with a driving range of 500 km. To ensure a range of 500 km, the battery BAT needs to have an electric energy of about 50 kWh. If the output of the quick charger 14 is 3 MW, this electric vehicle can be fully charged in about one minute, the same as an existing gasoline vehicle. If the output of the inverter 11 is about 50 kW, the installation space for the inverter 11 is 0.5 m 3 If the energy storage capacity of the flywheel 12 is 50 kWh, the installation space for the flywheel 12 needs to be 1.4 m 3 If the output of the quick charger 14 is 3 MW, the installation space for the quick charger 14 must be 3 m 3 If the output of the inverter 11 is 50 kW, the flywheel 12 with an energy storage capacity of 50 kWh can be fully charged in about 60 minutes.

[0029] FIG. 4 is a graph showing the change in charging power (kW: left vertical axis) of quick charger 14 and the kinetic energy filling rate (%: right vertical axis) of flywheel 12 over time (min: horizontal axis) assuming that the voltage of the input power is AC 200V, the output of inverter 11 is 50kW, the output of quick charger 14 is 3MW, and the energy storage amount of flywheel 12 is 50kWh.

[0030] According to Fig. 4, since the introduced power is low voltage, it takes a certain time to fully charge the kinetic energy of the flywheel 12, but charging is completed in an extremely short time. Therefore, the user can charge the vehicle V in the same time as an existing gasoline vehicle. Note that it is not preferable to completely stop the flywheel 12 during charging, and it is preferable to complete charging when the kinetic energy charging rate reaches, for example, 3 to 5%.

[0031] As described above, the charging system 10 of the present embodiment can be installed in a relatively small space, so that the degree of freedom in installation is high and many charging stations can be provided to users.

[0032] [Flywheel] Next, the flywheel 12 will be described with reference to FIG.

[0033] 5, the flywheel 12 includes a rotor 62 mechanically connected to a rotor 131 of the motor generator 13 via a rotating shaft 61 along the vertical direction, a pair of upper and lower journal bearings 63 and pivot bearings 64 that support the rotating shaft 61, an electromagnet 65 arranged to face an upper surface of the rotor 62, and a case 66 that houses the rotating shaft 61, the rotor 62, the journal bearings 63, the pivot bearing 64, and the electromagnet 65. The case 66 may be integral with a motor case (not shown) that houses the motor generator 13, or may be a separate body. The electromagnet 65 is an example of a magnetic body.

[0034] (Rotor) The rotor 62 is required to be heavy and rotate at high speed (hereinafter also referred to as high rotation) to improve the energy density of the flywheel 12. Conventionally, heavy iron or high-strength CFRP (carbon fiber reinforced plastic) has been used as the material for the rotor 62. Iron materials may lack strength at high rotation, so materials with increased strength such as molybdenum and carbon steel are used to address this, but there is a limit to how high the rotation can be. CFRP-based materials are strong and suitable for high rotation, but because of their light specific gravity, they require higher rotation than iron-based materials for energy storage. In addition, resin is used to harden the CFRP, but there is a concern that the strength will decrease due to deterioration of the resin when used for a long period of time, so they are not necessarily the most suitable material.

[0035] The rotor 62 of this embodiment is formed using a material with high strength and high specific gravity. The high strength and high specific gravity material is, for example, tungsten. Such a rotor 62 is heavy and can be rotated at high speed, so that the energy density is increased. The rotor 62 containing tungsten will be described below as an example.

[0036] The rotor 62 integrally includes a low magnetic region 621 containing a large amount of tungsten and having a low magnetic degree (second magnetic degree) and a high magnetic region 622 containing a large amount of magnetic material (iron, cobalt, nickel, etc.) and having a high magnetic degree (first magnetic degree) at different positions in the rotation axis direction of the rotor 62. That is, the low magnetic region 621 is a region having a lower magnetic degree than the high magnetic region 622, and the magnetic degree may be zero. For example, the rotor 62 of this embodiment includes the low magnetic region 621 on the lower side in the rotation axis direction and the high magnetic region 622 on the upper side in the rotation axis direction.

[0037] Moreover, it is preferable that the high magnetic region 622 is a low specific gravity region having a low specific gravity (also called a small specific gravity), and the low magnetic region 621 is a high specific gravity region having a higher specific gravity (also called a large specific gravity) than the high magnetic region 622. Since the low magnetic region 621 has a high specific gravity, it is possible to increase the weight of the rotor 62 and increase the energy density.

[0038] To manufacture such a rotor 62, for example, tungsten powder and binder material (powders of iron, cobalt, nickel, etc.) are pressed together to form a chalk-like shape. At this time, the rotor 62 is made 20 to 30% larger in size to accommodate shrinkage in the next process. Also, in order to make the upper part of the rotor 62 a highly magnetic region 622, the ratio of binder material in the upper part of the rotor 62 is increased. Next, the rotor 62 is sintered at a high temperature of 1800°C to 3000°C to form a high-density tungsten solid metal. Next, the rotor 62 is heated again to about 2500°C to 3000°C, and forged to gradually shape it. The final shaping is performed by electric discharge machining, electric discharge wire machining, laser machining, etc.

[0039] (Bearings) The pair of journal bearings 63 support the rotating shaft 61 so as to be rotatable around the rotation axis and slidable in the direction of the rotation axis. The pivot bearing 64 rotatably supports the lower end of the rotating shaft 61. The pivot bearing 64 is a bearing that receives the lower end 611 (pivot) of the rotating shaft 61, which is conical and slightly rounded at the tip, with a concave surface 641, and the concave surface 641 is filled with oil. As a bearing that supports the rotating shaft 61, a radial bearing (rolling bearing) may be used instead of the journal bearing 63 (slide bearing), and a non-lubricated bearing (air bearing, magnetic bearing, etc.) or a float bearing (full-float bearing, semi-float bearing, etc.) may be used instead of the pivot bearing 64.

[0040] (electromagnet) The electromagnet 65 is disposed so as to face the upper surface (highly magnetic region 622) of the rotor 62, and attracts the highly magnetic region 622 of the rotor 62 by a magnetic force generated when current is applied, thereby levitating the rotor 62. This not only reduces friction of the pivot bearing 64, and reduces wear and energy loss of the pivot bearing 64, but also makes a special bearing unnecessary. As a result, it is possible to improve durability and energy density and reduce costs.

[0041] In order to stably levitate the rotor 62, it is necessary to adjust the pulling magnetic force acting on the rotor 62 so as to balance with gravity. In this embodiment, a plurality of electromagnets 65 are arranged at predetermined intervals in the circumferential direction above the rotor 62, and the strength of the magnetic force generated by the plurality of electromagnets 65 is adjusted by current control, thereby enabling stable levitation of the rotor 62. Note that although the electromagnet 65 is exemplified as the magnetic body, the rotor 62 may be levitated using a permanent magnet instead of the electromagnet 65. When the electromagnet 65 is used, a mechanical mechanism for finely adjusting the position of the permanent magnet is not required.

[0042] Furthermore, the electromagnets 65 are disposed on the opposite side of the rotor 62 from the pivot bearing 64 in the direction of the rotation axis. This allows for more efficient use of space than if they were disposed on the same side as the pivot bearing 64.

[0043] Furthermore, the rotor 131 of the motor generator 13 is disposed above a plurality of electromagnets 65, and is supported by a pair of journal bearings 63 and pivot bearings 64 via the rotating shaft 61 of the rotor 62. This eliminates the need for a dedicated bearing structure for supporting the rotor 131 of the motor generator 13.

[0044] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can come up with various modified or revised examples within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present invention. Furthermore, the components in the above-mentioned embodiments may be arbitrarily combined within the scope of the invention.

[0045] For example, in the embodiment described above, the upper part of the rotor 62 is made into a high magnetic region 622, the lower part of the rotor 62 is made into a low magnetic region 621, and the electromagnet 65 is arranged above the rotor 62 to levitate the rotor 62, but the lower part of the rotor 62 may be made into a high magnetic region 622, the upper part of the rotor 62 is made into a low magnetic region 621, and the electromagnet 65 may be arranged below the rotor 62 to levitate the rotor 62.

[0046] This specification describes at least the following items. Note that, in parentheses, corresponding components and the like in the above-mentioned embodiment are shown, but the present invention is not limited to these.

[0047] (1) a rotor (rotor 62) mechanically connected to a rotor (rotor 131) of a rotating electric machine (motor generator 13); A kinetic energy storage device (flywheel 12) including a support portion (journal bearing 63, pivot bearing 64) that rotatably supports the rotating body, The rotating body is provided at different positions in the rotation axis direction (up-down direction) of the rotating body. a first region having a first degree of magnetism (highly magnetic region 622); a second region (low magnetic region 621) that is less magnetic than the first region.

[0048] According to (1), the difference in the degree of magnetism of the rotors can be utilized to move the rotors in the direction of their rotation axis, thereby reducing loss in the rotors.

[0049] (2) A kinetic energy storage device according to (1), The kinetic energy storage device includes a magnetic body (electromagnet 65) at a position facing the first region.

[0050] According to (2), the magnetic force of the magnetic body can be used to move the rotating body in a direction toward the magnetic body or in a direction away from the magnetic body.

[0051] (3) A kinetic energy storage device according to (2), The rotating body is disposed such that the rotation axis is aligned along a vertical direction, The first region is disposed at a higher position than the second region, The magnetic body is disposed above the first region.

[0052] According to (3), since the bearing-related structure is larger on the lower side of the rotating body, the space can be efficiently utilized by arranging the magnetic body on the upper side of the rotating body.

[0053] (4) A kinetic energy storage device according to (3), The rotor is a kinetic energy storage device disposed above the magnetic body and supported by the support portion via the rotating body;

[0054] According to (4), since the rotor is supported by the support portion via the rotor, a bearing structure for supporting only the rotor can be omitted or simplified.

[0055] (5) A kinetic energy storage device according to any one of (1) to (4), the first region has a first specific gravity; The second region has a second specific gravity greater than the first specific gravity.

[0056] According to (5), since the specific gravity of the second region is large, the weight of the rotor can be increased, and the energy density can be increased. [Explanation of symbols]

[0057] 12 Flywheel (kinetic energy storage device) 13 Motor generator (rotating electric machine) 131 Rotor 62 Rotor (rotating body) 621 Low magnetic region (second region) 622 Highly magnetic region (1st region) 63 Journal bearing (support part) 64 Pivot bearing (support part) 65 Electromagnet (magnetic material)

Claims

1. a rotor that is mechanically connected to a rotor of a rotating electric machine; A kinetic energy storage device comprising: The rotating body is provided at different positions in the rotation axis direction of the rotating body. A kinetic energy storage device having integrally therewith a first region having a first degree of magnetic property and a second region having a lesser degree of magnetic property than the first region.

2. 2. The kinetic energy storage device of claim 1, A kinetic energy storage device comprising a magnetic body at a position facing the first region.

3. 3. The kinetic energy storage device of claim 2, The rotating body is disposed such that the rotation axis is aligned along a vertical direction, The first region is disposed at a higher position than the second region, The magnetic material is disposed above the first region.

4. 4. The kinetic energy storage device of claim 3, The rotor is a kinetic energy storage device disposed above the magnetic body and supported by the support portion via the rotating body;

5. A kinetic energy storage device according to any one of claims 1 to 4, the first region has a first specific gravity; The second region has a second specific gravity greater than the first specific gravity.

6. A kinetic energy storage device according to any one of claims 1 to 5, the rotating body is a sintered body of metal powder, The metal powder is a mixed powder including a first metal powder and a second metal powder, the first metal powder is more magnetic than the second metal powder; A kinetic energy storage device, wherein a content ratio of the first metal powder in the first region is higher than a content ratio of the first metal powder in the second region.

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