Mechanical device for converting direct current into alternating current

Abstract

The present invention relates to a mechanical device (3) for converting direct current into three-phase alternating current for driving a rotating electric machine, the mechanical device having at least one contact unit having at least two receiving regions (12, 13) for receiving electrical energy in the form of direct current and at least three output regions (9, 10, 11) for outputting electrical energy in the form of alternating current, wherein a first receiving region is designed to contact the positive pole of a direct current feed, wherein a second receiving region is designed to contact the negative pole of a direct current feed, wherein a first output region is designed to provide a first alternating current, wherein a second output region is designed to provide a second alternating current, wherein a third output region is designed to provide a third alternating current, and at least one contact unit for receiving direct current and / or for outputting alternating current. The present invention also relates to a rotating electric machine having such a device.

Description

Technical Field

[0001] The present invention relates to a mechanical device for converting direct current into three-phase alternating current for driving a rotating electric machine.

[0002] Furthermore, the present invention relates to a rotating electric machine having such a mechanical device. Background Art

[0003] DC voltage networks are becoming increasingly popular in industrial networks. Power supplies with direct current offer great energy-saving potential and are particularly suitable for drives in production. Also in vehicles, robots, load-carrying robots, and other battery networks, in most cases only direct current voltage is available.

[0004] In order to be able to operate a rotating electric machine having a polyphase stator winding in a DC voltage network (also referred to as a DC network), an electronic circuit for generating a polyphase alternating voltage from the DC voltage is used. This enables the multi-strand windings of the rotating electric machine to be fed. Such an electronic circuit is particularly complex and lossy.

[0005] Due to the fact that such an electronic circuit also has a certain complexity, the object of the present invention is to reduce the complexity of converting direct current into three-phase alternating current for driving a rotating electric machine. Summary of the Invention

[0006] This object is achieved by the present invention, namely a mechanical device for converting direct current into three-phase alternating current for driving a rotating electric machine, having at least one contact unit, the contact unit having at least two receiving regions for receiving electrical energy in the form of direct current, and at least three output regions for outputting electrical energy in the form of alternating current, wherein a first receiving region is designed to contact the positive pole of the DC feed, wherein a second receiving region is designed to contact the negative pole of the DC feed, wherein a first output region is designed to provide a first alternating current, wherein a second output region is designed to provide a second alternating current, wherein a third output region is designed to provide a third alternating current, and having at least one contact unit for receiving direct current and / or for outputting alternating current.

[0007] Furthermore, this object is achieved by a rotating electric machine having such a mechanical device.

[0008] The rotating electric machine has a rotor and a stator. The present invention can be used both for permanently excited or electrically excited synchronous machines and for reluctance machines.

[0009] Further advantageous embodiments result from the present invention.

[0010] In an advantageous embodiment of the present invention, the contact unit can be mounted on the shaft of the rotating electric machine.

[0011] This offers the advantages of an existing rotating electrical machine with a multi-strand, in particular three-strand, stator winding, since the mechanical device is implemented to be mounted on the shaft in a simple manner.

[0012] In a further advantageous embodiment of the invention, the mechanical device is designed as a hollow cylinder.

[0013] This has the advantage that, on the one hand, the mechanical device can be mounted on the shaft and, on the other hand, it can be adapted to the dimensions of the rotating electrical machine.

[0014] In a further advantageous embodiment of the invention, the first and / or second receiving areas are located on at least one slide rail arranged at least substantially concentrically around a central point.

[0015] This is advantageous since the reception of electrical energy is related to the rotation of the rotor.

[0016] In a further advantageous embodiment of the invention, the first and / or second and / or third output areas are located on at least one slide rail arranged at least substantially concentrically around a central point.

[0017] This is advantageous since the output of electrical energy is related to the rotation of the rotor.

[0018] In a further advantageous embodiment of the invention, the contact unit is designed as a disk.

[0019] This sometimes offers the advantage of a compact structure of the rotating electrical machine.

[0020] In a further advantageous embodiment of the invention, the first output area is located on a first slide rail, the second output area is located on a second slide rail, and the third output area is located on a third slide rail.

[0021] In a further advantageous embodiment of the invention, the first and second receiving areas are located on just a fourth slide rail, where the first receiving area is located on a first section of the fourth slide rail and the second receiving area is located on a second section of the fourth slide rail.

[0022] These sections are advantageous, in particular the section dimensions depending on the number of poles p of the electrical machine. Exemplarily, it can be specified that: α = 120° / p.

[0023] The described device is preferably designed as a sliding contact switch.

[0024] In another advantageous embodiment of the present invention, the contact unit is designed to be connected to the shaft of a rotary electric machine and has at least three contact elements, wherein the first contact element is configured such that during rotation of the shaft in the first slide rail, the first and second contact elements alternately connect the first output region to the first receiving region and the second receiving region, wherein the second contact element is configured such that during rotation of the shaft in the second slide rail, the second contact element alternately connects the second output region to the first receiving region and the second receiving region, and wherein the third contact element is configured such that during rotation of the shaft in the third slide rail, the third contact element alternately connects the third output region to the first receiving region and the second receiving region.

[0025] This has the advantage that by this embodiment, the DC voltage is controlled by the rotor position and switched via the contact elements at a fixed angle to the multi-strand stator winding.

[0026] Exemplarily, for a case of a large number of strands m, the angle α between two strands mech Applies to: α mech = α el / p, where α el = 360° / m.

[0027] The number of segments is exemplarily 2p.

[0028] In another advantageous embodiment of the present invention, the first receiving region is located on a first receiving slide rail, wherein the first receiving slide rail is arranged at the outer circumference of a contact unit designed as a hollow cylinder, wherein the second receiving region is located on a second receiving slide rail, and wherein the second receiving slide rail is arranged at the outer circumference of the contact unit.

[0029] This is advantageous because the reception of electrical energy is related to the rotation of the rotor.

[0030] In another advantageous embodiment of the present invention, the first output region and the second output region and the third output region are arranged on exactly one output slide rail, wherein the output slide rail is arranged at the outer circumference of a contact unit designed as a hollow cylinder, wherein the first output region is located on the first segment of the output slide rail, wherein the second output region is located on the second segment of the output slide rail, and wherein the third output region is located on the third segment of the output slide rail.

[0031] Exemplarily, these segments electrically have 120°. Advantageously, there are 3p segments at the circumference.

[0032] Such an embodiment is particularly suitable for a reluctance motor.

[0033] For this purpose, the rotor is constructed as a reluctance rotor, so that different permeance values are present on the d-axis and the q-axis.

[0034] Direct current is preferably transmitted via a fixed brush to a commutator fixed on or at the rotor. There, the current position is preferably transmitted to the stator winding via the brush correctly. Thus, the machine does not require any rotor position sensors.

[0035] This has the advantage that the reluctance motor can be operated directly at the DC network. A machine with a robust rotor structure, compact dimensions and low cost can be operated directly at the DC network.

[0036] The reluctance motor has no windings on the rotor and preferably comprises stamped laminations. Thus, there are fewer losses on the rotor. The reluctance motor has a small inertia and is inexpensive. The robust structure also enables applications in a high temperature range, for example for fans for smoke ventilation or fresh air overpressure in case of fire. Especially in these applications, a battery-buffered DC network is preferably used. On the one hand, there is no converter, and on the other hand, the position sensor is in the machine, which is particularly advantageous in such applications.

[0037] In another advantageous embodiment of the invention, the first output area is located on the first output slide rail, and the second output area is located on the second output slide rail, and the third output area is located on the third output slide rail, wherein the first output slide rail and the second output slide rail and the third output slide rail are implemented at the outer circumference of a contact unit designed as a hollow cylinder.

[0038] In another advantageous embodiment of the invention, the first output area is divided into a plurality of output area segments, wherein the second output area is divided into a plurality of output area segments, wherein the third output area is divided into a plurality of output area segments.

[0039] In another advantageous embodiment of the invention, the plurality of output area segments correspond to the plurality of pole numbers of the stator winding of the rotary electric machine, wherein the first output area segment is connected to the first receiving area, and wherein adjacent second output area segments are connected to the second receiving area.

[0040] The mechanical device described in this embodiment preferably includes at least one sliding contact for each phase and at least one sliding contact for each pole of the DC voltage, i.e., at least five sliding contacts in a machine with a three-phase stator winding, preferably implemented as brushes.

[0041] The sliding contact is preferably implemented as a fixed brush, and the mechanical device rotates with the rotor when the rotor rotates. The fixed brush is pre-tensioned and pressed against the assigned receiving and output slide rails, thus optimally ensuring current flow.

[0042] In this embodiment, the mechanical device is preferably implemented for being rotatable or adjustable relative to the stator winding and / or the rotor, so as to feed current to each phase for an optimal rotor position. The optimal current fed into the polyphase stator winding is predetermined by fixing the position of the brush and the arrangement of the slide rail. For example, in the case of a three-phase stator winding, the current is fed with an electrical offset of 120°.

[0043] The present invention provides advantages that the use of a DC motor can be omitted. Thereby, good heat dissipation of the rotor and the motor can be achieved, while in a DC motor, the windings are located in the rotating part of the motor, making it difficult to cool the rotor. The present invention can also achieve higher rotational speed stability than a DC motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The present invention will be described and explained in more detail below with reference to the embodiments shown in the drawings. The drawings show:

[0045] Figure 1 A rotating electric machine is shown,

[0046] Figure 2 A first embodiment of the mechanical device is shown,

[0047] Figure 3 The result of the conversion from direct current to three-phase alternating current is shown,

[0048] Figure 4 Another embodiment of the mechanical device is shown,

[0049] Figure 5 Another embodiment of the mechanical device is shown,

[0050] Figure 6 Shown in Figure 5 An embodiment of the internal connection of the embodiment of the mechanical device shown in

[0051] Figure 7 A device for suppressing brush sparks during high current loads is shown,

[0052] Figure 8 Shown from another perspective is the Figure 7 device. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] Figure 1 A rotating electric machine in the form of a motor is shown.

[0054] The multi-strand motor 1 is coupled to the mechanical device 3 according to the present invention. In Figure 1 , the mechanical device 3 is a sliding contact switch and is fed with direct current by the DC feed 5. In Figure 1 , both the motor 1 and the sliding contact switch 3 are coupled to the shaft 2.

[0055] Figure 2 Shows a first embodiment of the mechanical device 3.

[0056] Figure 2 Shows the mechanical device 3 implemented as a disk or contact disk. The mechanical device 3 is adapted to be fixed at the stator of a rotating electric machine.

[0057] The mechanical device 3 is implemented as Figure 2 a contact disk, where the contact disk is an embodiment of a hollow cylinder.

[0058] The mechanical device 3 has a first output region 9, a second output region 10, and a third output region 11. In Figure 2 it, the first output region 9 is implemented as a slide rail for the first phase L1, the second output region 10 is implemented as a slide rail for the second phase L2, and the third output region 11 is implemented as a slide rail for the third phase L3.

[0059] Furthermore, Figure 2 the mechanical device 3 in

[0060] includes a first receiving region 12 and a second receiving region 13. These two receiving regions 12 and 13 are located on just one slide rail that at least partially follows a circular track arranged concentrically around the center point M.

[0061] The slide rails 9, 10, 11 also at least partially follow a circular track arranged concentrically around the center point M.

[0062] Figure 2 Shows the contact disk 7 coupled to the shaft 2. The contact disk 7 is preferably fixedly connected to the stator.

[0063] Figure 2 Also shown are the connecting element 92, the connecting element 102, and the connecting element 112.

[0064] The contact element 91 is connected to the connecting element 92. The contact element 92 is connected to the connecting element 102. The contact element 111 is connected to the connecting element 112.

[0065] The contact elements 91, 101, and 111 can be connected to the shaft 2 by means of the connecting elements 92, 102, and 112.

[0066] When the shaft 2 rotates, the contact element 91, for example, connects the output region 9 to the receiving region 13 and then connects the output region 9 to the receiving region 12. In other words, the contact element 91 connects the slide rail for L1 to the negative pole and then connects the slide rail for L1 to the positive pole.

[0067] The same applies: The contact element 101 connects the slide rail for L2 to the negative pole and then connects the slide rail for L2 to the positive pole. The contact element 111 connects the slide rail for L3 to the negative pole and then connects the slide rail for L3 to the positive pole.

[0068] The lengths of the receiving areas 12 and 13 on the slide rail are selected to form a three-phase alternating current.

[0069] The multi-strand stator winding can be fed by means of the mechanical device 3, the sliding contact switch.

[0070] The connecting element is preferably implemented as a brush, especially a carbon brush.

[0071] As already explained, the contact points 91, 101 and 111 are connected to the shaft 2 via the connecting element and thus to the rotor.

[0072] If the receiving areas 12 and 13 are in contact with the DC voltage, which output area can provide which current is controlled by the position of the rotor. The output area can be implemented as a contact ring. The receiving area can be implemented as a commutator ring.

[0073] Figure 3 The result of the conversion from direct current to three-phase alternating current is shown. Figure 3 It shows how to feed the three strands of the rotating electrical machine based on the DC feed by means of the mechanical device 3.

[0074] Figure 3 The feeding of the three strands L1, L2 and L3 is shown, where A represents one turn of the two-pole motor.

[0075] It is shown in this figure that the positive current ranges of the individual strands are phase-shifted by 120 °C, which is the same as in the case of three-phase alternating current.

[0076] Figure 4 Another embodiment of the mechanical device 3 is shown.

[0077] Figure 4 A commutator with a sliding contact 8 is shown, which can be mounted on the shaft. The mechanical device 3 is implemented as a hollow cylinder. The mechanical device 3 has a first receiving area for contacting the positive pole of the DC feed 12 and a second receiving area for contacting the negative pole of the DC feed 13.

[0078] In Figure 4 the first receiving area at the front axial end V of the hollow cylinder is implemented as a track surrounding the outer circumference of the hollow cylinder. In Figure 4 the second receiving area at the rear axial end H of the hollow cylinder is implemented as a track surrounding the outer circumference of the hollow cylinder.

[0079] Figure 4Three output regions 9, 10, and 11 are also shown, which are arranged mechanically offset by 60° (60° mechanically corresponding to 180° electrically) at the circumference.

[0080] Output regions 9 and 10 are advantageously connected to DC+, and output region 11 is connected to DC-.

[0081] Figure 4 It is shown that each receiving region and each output region can be contacted via contacts 20 and springs 30. The first receiving region 12 and the second receiving region 13 are connected to the feeding DC system via contacts 20 and springs 30. This is Figure 4 shown as DC+ and DC- in

[0082] The three output regions 9, 10, and 11 can be contacted via springs 30 and contacts 20 with phases L1, L2, and L3, which represent the energy supply of the motor.

[0083] Figure 4 A mechanical device 3 suitable for a three-strand rotating electric machine with six poles is shown.

[0084] Figure 5 Another embodiment of the mechanical device 3 is shown.

[0085] The mechanical device 3 is implemented as a hollow cylinder and can be coupled to the shaft of the rotating electric machine by means of a shaft adapter 41. The mechanical device 3 should not be rotatably mounted when coupled to the shaft. Figure 5 An insulator 40 is shown. Figure 5 The first receiving region 12, the second receiving region 13, and the three output regions 9, 10, and 11 are also shown.

[0086] Figure 5 It is shown that each receiving region and each output region can be contacted via contacts 20 and springs 30. The first receiving region 12 and the second receiving region 13 are connected to the feeding DC system via contacts 20 and springs 30. This is Figure 5 shown with DC+ and DC- in

[0087] Figure 5 A mechanical device 3 suitable for a three-strand rotating electric machine with six poles is shown.

[0088] The first output region 9 is divided into a plurality of output region segments in the figure. The second output region 10 is divided into the same plurality of output region segments. The third output region 11 is divided into the same plurality of output region segments.

[0089] The number of output region segments preferably corresponds to the number of poles of the stator winding of the rotating electric machine, wherein the first output region segment 9A is connected to the first receiving region 12, and the adjacent second output region segment 9B is connected to the second receiving region 13. This isFigure 6 is described in more detail below.

[0090] Figure 6 shows an embodiment of the internal connection of the mechanical device shown in Figure 5 below.

[0091] The first output area section 9A is connected to the first receiving area 12, and the adjacent second output area section 9B is connected to the second receiving area 13. Another adjacent third output area section 9C is also connected to the second receiving area 13.

[0092] The output area section 9D is connected to the first receiving area 12 in the figure. The system will be transferred to two other slide rails.

[0093] Figure 7 shows a device for suppressing brush sparking during high current loads.

[0094] The mechanical devices described in the previous figures in various embodiments can generate brush sparking during high current loads. Such brush sparking should be suppressed to a large extent.

[0095] Figure 7 shows the insulator 50 and the slide rails 53, 52 and 51, and the direction of movement R. Figure 7 shows the brush bridge 55, which has a no-load diode D for suppressing brush sparking. The figure also shows the contacts K coupled to DC+ or DC- or L1, L2 or L3.

[0096] This has the advantage of suppressing brush sparking that causes high wear, for example. The no-load diode D arranged in the brush bridge allows the no-load current to be drawn without generating sparks.

[0097] Figure 8 shows the device from Figure 7 from another perspective, so to speak, an unfolded perspective.

[0098] Figure 8 shows the slide rails 53, 52 and 51, the brush bridge 55 and the no-load diode D for suppressing brush sparking. The figure shows the arrangement of the stator windings and the contacts K1...K4 in the star connection 54.

[0099] The device is applicable to a six-pole three-phase motor.

Claims

1. A mechanical device (3) for converting direct current into three-phase alternating current for driving a rotating electric machine, the mechanical device having: - At least one contact unit having at least two receiving areas (12, 13) for receiving electrical energy in the form of direct current and at least three output areas (9, 10, 11) for outputting electrical energy in the form of alternating current, wherein, the first receiving area is designed to contact the positive pole of the direct current feed, wherein the second receiving area is designed to contact the negative pole of the direct current feed, wherein the first output area is designed to provide a first alternating current, wherein the second output area is designed to provide a second alternating current, wherein the third output area is designed to provide a third alternating current, and - At least one contact unit for receiving direct current and / or for outputting alternating current, - wherein the three output areas (9, 10, 11) can be brought into contact with the phases L1, L2 and L3 of the electric machine via springs (30) and via contacts (20), wherein an insulator (40) is designed between two output areas (9, 10, 11) and the contacts (20) such that the contacts (20) do not contact two output areas (9, 10, 11) simultaneously, wherein the first output area (9) is located on a first slide rail, wherein the second output area (10) is located on a second slide rail, wherein the third output area (11) is located on a third slide rail, wherein the contact unit can be mounted on the shaft (2) of the rotating electric machine.

2. The mechanical device (3) according to claim 1, wherein, the contact unit is designed as a hollow cylinder.

3. The mechanical device (3) according to any one of claims 1 to 2, wherein, the first receiving area and / or the second receiving area (12, 13) are located on at least one slide rail arranged at least substantially concentrically around a center point (M).

4. The mechanical device (3) according to any one of claims 1 to 2, wherein, the first output area and / or the second output area and / or the third output area (9, 10, 11) are located on at least one slide rail arranged at least substantially concentrically around a center point (M).

5. The mechanical device (3) according to any one of claims 1 to 2, wherein, the contact unit is designed as a disc.

6. The mechanical device (3) according to claim 1, wherein, the first receiving area and the second receiving area are located on exactly one fourth slide rail, wherein the first receiving area is located on a first section of the fourth slide rail and the second receiving area is located on a second section of the fourth slide rail.

7. The mechanical device (3) according to claim 1, wherein, the contact unit is designed to be connected to the shaft of the rotating electric machine, wherein the contact unit has at least three contact elements, wherein the first contact element is designed such that during rotation of the shaft of the first slide rail, the first contact element alternately connects the first output area to the first receiving area and the second receiving area, Wherein, the second contact element is designed such that during the rotation of the axis of the second slide rail, the second contact element alternately connects the second output area to the first receiving area and the second receiving area. Wherein, the third contact element is designed such that during the rotation of the axis of the third slide rail, the third contact element alternately connects the third output area to the first receiving area and the second receiving area.

8. The mechanical device (3) according to claim 2, Wherein, The first receiving area is located on a first receiving slide rail, wherein the first receiving slide rail is arranged at the outer circumference of the contact unit designed as a hollow cylinder, wherein the second receiving area is located on a second receiving slide rail, wherein the second receiving slide rail is arranged at the outer circumference of the contact unit.

9. The mechanical device (3) according to claim 2, Wherein, The first output area, the second output area, and the third output area are located on exactly one output slide rail, wherein the output slide rail is arranged at the outer circumference of the contact unit designed as a hollow cylinder, Wherein, the first output area is located on the first section of the output slide rail, wherein the second output area is located on the second section of the output slide rail, wherein the third output area is located on the third section of the output slide rail.

10. The mechanical device (3) according to claim 2, Wherein, The first output area is located on a first output slide rail, and the second output area is located on a second output slide rail, and the third output area is located on a third output slide rail, wherein the first output slide rail, the second output slide rail, and the third output slide rail are arranged at the outer circumference of the contact unit designed as a hollow cylinder.

11. The mechanical device (3) according to claim 10, Wherein, The first output area is divided into a plurality of output area segments, wherein the second output area is divided into a plurality of output area segments, wherein the third output area is divided into a plurality of output area segments.

12. The mechanical device (3) according to claim 11, Wherein, The plurality of output area segments correspond to the number of poles of the stator winding of the rotating electric machine, wherein the first output area segment is connected to the first receiving area, and the adjacent second output area segments are connected to the second receiving area.

13. A rotating electric machine having the mechanical device (3) according to any one of claims 1 to 12.

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