Drive device

Abstract

To provide a drive device capable of improving insulation performance regardless of a capacitance ratio between a capacitance between stator winding cores and a capacitance between a stator core and a housing frame.SOLUTION: A drive device 1 includes an inverter power supply 2 and a motor 3. The motor 3 includes: a cylindrical stator 31; a rotor 32 that rotates inside or outside the stator 31; and a rotating shaft 37 provided coaxially with the rotor 32. The stator 31 is mechanically fixed to a rotary machine housing 33 and includes a stator core 34 and a stator winding 35 that is formed of coils of a plurality of phases wound about the stator core 34 and generates a rotating magnetic field. The rotating shaft 37 is rotatably supported by the rotary machine housing 33 via a bearing 37. The coils of the plurality of phases are connected to an electrically neutral point to form a star connection. The stator core 34 is electrically insulated from an electric apparatus housing 33 and electrically connected to the neutral point.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a drive device. [Background technology]

[0002] In Patent Document 1, the stator core of a rotating electric machine that generates a rotating magnetic field is fastened to a grounded housing frame via an insulator to electrically insulate it from the housing frame. According to this technology, the common mode voltage output from a grounded inverter power supply is shared not only by the capacitance between the stator winding core as in the normal case, but also by the capacitance between the stator core and the housing frame, thereby reducing the surge voltage between the windings caused by the common mode voltage and improving insulation performance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-185020 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, if the capacitance ratio between the capacitance with the stator winding core and the capacitance between the stator core and the housing frame is large, the surge voltage reduction effect cannot be achieved and the insulation performance deteriorates.

[0005] The present disclosure has been made in consideration of the above, and aims to provide a drive device that can improve insulation performance regardless of the capacitance ratio between the capacitance between the stator winding core and the capacitance between the stator core and the housing frame. [Means for solving the problem]

[0006] In order to solve the above problems and achieve the object, the driving device according to the present disclosure is a driving device including a rotating electric machine installed inside a rotating electric machine housing, and an electric device that supplies power to the rotating electric machine and is mechanically fixed inside a conductive electric device housing, the electric device having a DC power generation device and a power conversion device that converts DC power from the DC power generation device into AC power, the rotating electric machine having a cylindrical stator, a rotor that rotates inside or outside the stator, and a power converter that is synchronous with the rotor. The rotating electric machine has a rotating shaft provided on a shaft, the stator is mechanically fixed to the rotating electric machine housing and is composed of a stator core and a stator winding consisting of multiple phase coils wound around the stator core and generating a rotating magnetic field, the rotating shaft is rotatably supported on the rotating electric machine housing via bearings, the multiple phase coils are connected to an electrical neutral point to form a star connection, and the stator core is electrically insulated from the electrical equipment housing and electrically connected to the neutral point. Effect of the Invention

[0007] According to the present disclosure, it is possible to achieve the effect of improving insulation performance regardless of the capacitance ratio between the capacitance with the stator winding core and the capacitance between the stator core and the housing frame. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing a configuration of a drive device according to a first embodiment. [Diagram 2] FIG. 2 is a circuit diagram of the driving device according to the first embodiment. [Diagram 3] FIG. 3 is a graph showing the relationship between the common mode voltage Vcc'' and the capacitance ratio Ccf / Ccc. [Figure 4] FIG. 4 is a graph showing the measurement results of the potential difference between the coils in the conventional art and in the first embodiment when the capacitance ratio Ccf / Ccc is set to 100. In FIG. [Diagram 5] FIG. 5 is a schematic diagram showing a configuration of a drive device according to the second embodiment. [Figure 6]FIG. 6 is a diagram for explaining a schematic diagram of stator core-to-rotor core stray capacitance in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a driving device according to an embodiment of the present disclosure will be described with reference to the drawings. Note that the components in the following embodiments include those that are replaceable and easy for a person skilled in the art, or those that are substantially the same. Also, each figure referred to in the following description merely shows the shape, size, and positional relationship roughly to the extent that the contents of the present disclosure can be understood. In other words, the present disclosure is not limited to only the shape, size, and positional relationship exemplified in each figure.

[0010] (Embodiment 1) [Configuration of the driving device] Fig. 1 is a schematic diagram showing the configuration of a drive device according to embodiment 1. Fig. 2 is a circuit diagram of the drive device according to embodiment 1. The drive device 1 shown in Fig. 1 includes an inverter power supply 2, a motor 3 which is a rotating electric machine, and a power line 4 which connects the inverter power supply 2 and the motor 3. The drive device 1 drives a load 5 by the rotation output of the motor 3.

[0011] [Configuration of inverter power supply] First, the configuration of the inverter power supply 2 will be described. The inverter power supply 2 includes a DC power generator 21 and a smoothing capacitor C for stabilizing the DC voltage. P ,C n , an inverter circuit 22, and an upper arm 23 and a lower arm 24 which electrically connect the DC power generation device 21 and the inverter circuit 22. The inverter power supply 2 and the DC power generation device 21 are mechanically fixed inside a conductive electrical device housing 25.

[0012] The inverter circuit 22 converts DC power from a DC power generation device into AC power. The inverter circuit 22 switches the DC voltage using switching elements such as FETs (Field Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors), converts it into AC voltage, and outputs it to the motor 3. In the first embodiment, the inverter circuit 22 functions as a power conversion device.

[0013] Smoothing capacitor C P One end of the smoothing capacitor C is electrically connected to the upper arm 23, and the other end of the smoothing capacitor C is electrically connected to the smoothing capacitor Cn. n One end of the smoothing capacitor C P and the other end is electrically connected to the lower arm 24.

[0014] Either the upper arm 23, the lower arm 24 or the midpoint is electrically connected to a conductive electrical device housing 25. Note that Fig. 1 illustrates a case where the midpoint is electrically connected to the conductive electrical device housing 25.

[0015] [Motor configuration] Next, the configuration of the motor 3 will be described. The motor 3 has a cylindrical stator 31 for creating a rotating magnetic field by a three-phase AC voltage and current, and a rotor 32 that rotates inside or outside the stator 31 in response to the rotating magnetic field. The stator 31 and the rotor 32 are housed in a rotating machine housing 33. The stator 31 is mechanically fixed to the rotating machine housing 33.

[0016] The stator 31 is configured using a stator core 34 and a stator winding 35 which is a coil wound around the stator core 34 and generates a rotating magnetic field.

[0017] The stator winding 35 is made up of coils of multiple phases, and these coils of multiple phases are connected to an electrical neutral point to form a star connection.

[0018] A rotating shaft 36 fixed to the rotor 32 is supported by a bearing 37 attached to the rotating machine housing 33. The rotating shaft 36 is coupled via an insulating coupling 39 to a rotating shaft 38 connected to the load 5 in order to rotate the load 5.

[0019] In the first embodiment, in particular, an insulator 40 is interposed between the stator 31 and the rotating machine casing 33, and the stator core 34 is at a floating potential with respect to the rotating machine casing 33. Furthermore, in the first embodiment, the stator core 34 is electrically connected to the neutral point of the stator winding 35, and the rotating machine casing 33 and the electric equipment casing 25 are electrically connected to each other.

[0020] In addition, in the motor 3, an insulator 40 is provided between the rotating machine casing 33 and a bearing 37 supporting the rotating shaft 36 of the rotor 32, so that the rotor 32 has a floating potential with respect to the rotating machine casing 33. The rotating shaft 36 of the rotor 32 at the floating potential is mechanically connected to a rotating shaft 38 connected to a load 5 that is generally at the same potential as the electrical equipment casing 25 by an insulating coupling 39, and is electrically insulated.

[0021] The insulator 40 is interposed between the stator 31 and the rotating machine housing 33, and is attached at least to a portion where the stator core 34 contacts the rotating machine housing 33. That is, the insulator 40 is provided on the yoke end surface portion 331 where the stator core 34 contacts the rotating machine housing 33, around the bolts 41 that fix the stator core 34 to the rotating machine housing 33, and under the heads of the bolts 41 or nuts. The insulator 40 can be a molded insulating plate or molded insulating tube such as an epoxy plate or FRP plate, but can also be formed by coating the outer periphery of the stator core 34 or the through holes of the fixing bolts with insulating varnish. The insulator 40 may be attached to the inner surface or bolt holes of the rotating machine housing 33 instead of the surface of the stator core 34.

[0022] Insulators 40 are also provided between the rotating machine housing 33 and the bearings 37 provided on both sides of the rotating shaft 36 inserted into the rotor 32. The insulators 40 are applied to the outer periphery of the bearing 37. The insulators 40 are also applied to the ball bearings and sliding surfaces inside the bearing 37 and the contact surface of the rotating shaft 36. It is desirable for the insulators 40 to have sufficient voltage resistance characteristics against the floating potential voltage of the rotor 32, and resins such as epoxy or polyester, ceramics such as alumina or silica, or composites of these are used.

[0023] The insulating coupling 39 connects the rotating shaft 36 on the rotor 32 side and the rotating shaft 38 on the load 5 side. The insulating coupling 39 insulates the rotor 32 from the load 5 by sandwiching an insulating plate 43 between flanges 42 attached to each of the rotating shafts 36 and 38, and by sandwiching the insulating plate 43 around the bolts 41 that secure the flanges 42 together and under the heads of the bolts 41 or nuts.

[0024] In the drive device 1 configured as above, as shown in FIG. 2, the stator core 34 is insulated from the rotating machine housing 33 and is connected to the electrical neutral point P1 of the stator winding. In the following, the stray capacitance between the coil and the core is referred to as C cc , stray capacitance C between the core and the housing cf The common mode voltage V cc '' is a variable k that is 1 when the upper arm 23 of each UVW phase is ON and 0 when the lower arm 24 is ON. u ,k v ,k w , the potential of the stator core is the electric neutral potential of the stator winding V nn teeth,

number

[0025] Figure 3 shows the common mode voltage V without any countermeasures. cc and the common mode voltage V according to Patent Document 1 (core insulation) cc ' and the common mode voltage V cc '' Regarding the capacitance ratio Ccf / C cc The vertical axis shows the relationship between the common mode voltage V cc In Figure 3, the line L1 represents the common mode voltage V cc and capacitance ratio C cf / C cc Curve L2 shows the relationship between the common mode voltage V cc ' and capacitance ratio C cf / C cc The line L3 indicates the relationship between the common mode voltage V cc '' and capacitance ratio C cf / C cc This shows the relationship between:

[0026] As shown by the line L3 in Figure 3, the capacitance ratio C cf / C cc Regardless of the common mode voltage V cc ''of

number

[0027] Figure 4 shows the capacitance ratio C cf / C cc 4 is a graph showing the measurement results of the potential difference between the coils of the conventional technique and the first embodiment when the capacitance ratio C is set to 100. In FIG. cf / C cc = 100, and curve L11 shows the measurement results of the first embodiment.

[0028] As shown by curve L11 in FIG. 4, the driver 1 can reduce the maximum voltage by approximately 18%.

[0029] According to the first embodiment described above, the stator core of the motor is insulated from the rotating machine housing, and the outer ring of the bearing is insulated from the rotating machine housing, and the rotor side and the load side are insulated by an insulating coupling. This insulation configuration improves the insulation of the motor 3, and at the same time, it is possible to prevent damage to the bearings and load side devices.

[0030] (Embodiment 2) Next, a second embodiment will be described. Fig. 5 is a schematic diagram showing the configuration of a drive device according to the second embodiment. Fig. 6 is a diagram for explaining the stator core-rotor core stray capacitance 100 of Fig. 5. Note that the same components as those of the drive device 1 according to the first embodiment are given the same reference numerals and detailed explanations are omitted.

[0031] A driving device 1A shown in Fig. 5 includes a motor 3A instead of the motor 3 according to the first embodiment. In the driving device 1A shown in Fig. 5 and Fig. 6, the stator core 34 and the rotating machine housing 33 are at the same potential, and the stator core 34 is electrically connected to the neutral point of the stator winding 35. In addition, the motor 3A has an insulator 40 interposed between the rotating machine housing 33 and the electric device housing 25, and the rotating machine housing 33 is at a floating potential from the electric device housing 25.

[0032] A rotating shaft 36 of the rotor 32 at floating potential is mechanically connected to, and electrically insulated from, a rotating shaft 38 connected to a load 5 at the same potential as the electrical equipment housing 25 by an insulating coupling 39.

[0033] According to the above-described embodiment 2, the rotating machine casing 33 also has the neutral potential of the stator 31 winding, so no potential difference occurs between the inside and outside of the bearing 37. In addition, since the rotating machine casing 33 and the stator 31 are not insulated, the fastening parts can be simplified and heat dissipation can be improved.

[0034] Further advantages and modifications may readily occur to those skilled in the art. The invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Thus, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and equivalents thereof.

[0035] Although some of the embodiments of the present application have been described in detail above with reference to the drawings, these are merely examples, and the present invention can be embodied in other forms that incorporate various modifications and improvements based on the knowledge of those skilled in the art, including the forms described in the disclosure of the present invention. [Explanation of symbols]

[0036] 1,1A driver 2 Inverter power supply 3,3A motor 4 Power line 5. Load 21 DC power generator 22 Inverter circuit 23 Upper Arm 24 Lower Arm 25 Electrical equipment housing 31 Stator 32 Rotor 33 Rotating Machine Housing 34 Stator core 35 Stator Winding 36,38 Rotation axis 37 Bearings 39 Insulating Coupling 40 Insulators 41 Volts 42 Flange 43 Insulating plate 100 Stray capacitance between rotor cores

Claims

[Claim 1] A drive device including a rotating electric machine installed inside a rotating electric machine housing, and an electric machine that supplies power to the rotating electric machine and is mechanically fixed inside a conductive electric machine housing, The electrical device includes: A DC power generator; a power converter for converting DC power from the DC power generator into AC power; having The rotating electric machine includes: A cylindrical stator; A rotor that rotates inside or outside the stator; A rotating shaft provided coaxially with the rotor; having The stator includes: The rotating electrical machine is mechanically fixed to the housing of the rotating electrical machine. A stator core; a stator winding that is made up of a plurality of phase coils wound around the stator core and generates a rotating magnetic field; It is composed of The rotation axis is The rotating electric machine housing is rotatably supported by a bearing, The multiple phase coils include Connected to the electrical neutral point to form a star connection, The stator core is The neutral point is electrically connected to the electrical equipment housing and electrically insulated from the electrical equipment housing. Drive unit.

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