DE19842523A1 - Electromagnetic energy converter e.g. brushless electric motor or magnetic bearing, has integrated circuit board located between stator winding heads - Google Patents

Abstract

The electromagnetic energy converter has a stator (7) provided with a stator winding, a rotor and a circuit board (3) for magnetic field sensors, located in a plane between the winding heads (1,5) of the stator, e.g. between 2 ferromagnetic stator lamination blocks (2,4), the external contour of the circuit board matched to the external contour of the latter, so that the winding slots are not obstructed.

Description

The invention relates to an electromagnetic energy converter according to the Preamble of the independent claim.

In electric drive technology, the brushless field-guided drives come into play growing importance. The intensified competitive situation in Germany and abroad, Sometimes stricter regulations and legislation, such as in the area of Heating technology, as well as ever increasing technical demands on the product lead to new, very customer- and cost-oriented drive solutions. The variety ranges from simple single-phase drive with uncontrolled speed up to complex, highly dynamic Servo drive systems that are linked together via fieldbuses.

While in the past, attempts were increasingly being made to carry out complex drive tasks with reinforced ones Solving the use of mechanical components today is usually the intelligence in the Electronics part relocated. The essential prerequisite for this development is Cost-effective availability of fast, highly integrated controls as well as of reliable, robust and highly dynamic power electronics circuits.

The trend to be observed towards increased use of electronics and material and production engineering simplified engine designs, if increased reliability, good efficiency and a long lifespan are aimed at growing Dimensions of drive concepts with brushless motors. The group is special here the permanent magnet motors as well as the asynchronous motors.

For extremely high demands on the speed range, service life, purity and the tightness of the drive system - essentially the areas of application that are under Using conventional storage techniques are not possible or are difficult to achieve, such as for example high-speed milling and grinding spindles, turbo compressors, Vacuum pumps, or pumps for high-purity chemical or medical products - are increasingly active magnetic bearings or motors with integrated magnetic bearing winding, also known as "bearingless motors".

Both with brushless motors, as well as with active magnetic bearings or bearingless The sensors prepare motors for measuring the air gap fields, the rotor angle and the radial one Distance between the rotor and stator or the axial displacement of the rotor in part significant technical and economic problems.

Many drive components are used to measure the air gap fields and thus indirect determination of the rotor position Hall sensors and for measuring the radial and axial distance between the stator and rotor eddy current sensors.

The measurement of the air gap field has so far been difficult because the Hall sensors result resulting assembly and connection problems, and not due to the lack of space can be reasonably accommodated in the air gap. The alternatives, the air gap stray field to be measured on the axial end faces of the rotor or specifically behind the main rotor attached additional permanent magnet rotor disks or rings are to be used not very satisfactory from a technical as well as from an economic point of view.

In the first case you do not measure the main field itself, but only one in the form stray field distorted and mostly very weak compared to the main field. Already minor  axial assembly tolerances of the rotor therefore lead in part to unsatisfactory. Measurement results and poor operating behavior of the drive.

In the second case, technically very good results can be achieved, the increased material and assembly effort for the auxiliary rotor are of great economic importance Disadvantage.

The radial and axial distance measurement in magnetic bearings or poses even greater problems bearingless motors with the help of eddy current sensors. These are very complex Manufacture of the magnetic coils, the exact placement and adjustment of the coils, the guide, Protection against damage and contacting of the fine electrical wire connections, as well as the implementation of defined connection lengths. The latter is regarding Influencing the capacitor coil resonant circuit of great importance, in particular if several eddy current sensors are used and these are individually tuned have to.

As with the Hall sensors, the spatial arrangement of the Eddy current sensors. For mounting in the air gap (ideal: in the middle of the air gap) is usually there is not enough space and there is an arrangement outside the air gap when tilting the rotor larger measurement errors with respect to the rotor distance, since the sensors and the tipping point is in different planes perpendicular to the rotor axis.

The object to be achieved by the invention is therefore to simplify the Sensor component with a simultaneous reduction in material, assembly and adjustment costs as well the provision of a robust industrial design.

The achievement of this task is based on the independent claim forth. Preferred embodiments are defined by the dependent claims.

Are of particular advantage in solving the problem according to the invention

• - the elimination of the individual production of the eddy current sensor coils,
• - the elimination of the installation of the eddy current sensor coils,
• - the provision of defined and reproducible coil connection lines,
• - The central arrangement of the eddy current and Hall sensors or other sensors in the Air gap of the machine or the magnetic bearing,
• - The possibility of a spatially close arrangement of the eddy current sensor, the Resonant circuit capacitor and the other sensor electronics,
• - The elimination of mechanical supports for positioning and securing the Hall sensors,
• - the elimination of the wire connections for the Hall sensors,
• - the exact alignment of the eddy current and Hall sensors with each other,
• The shielding of the electrical circuit by the ferromagnetic stator halves,
• - The integration of signal, power electronics and sensors on a circuit board directly on or in the stator,
• Possibility of good cooling of the power electronics semiconductors via the stator sheet,
• - The robust design of the sensors and the protection of the electrical components by the Arrangement between two stator halves,  
• - The feasibility of narrow air gaps despite the arrangement of the sensors in the axial Center of the air gap,
• The simple alignment of the printed circuit board and the stator laminations to one another,
• - The plug connections for signal, power and Sensor part,
• - Safety against wire breaks, as there are none apart from the (robust) drive windings Wire connections are required
• - The simple possibility of automatic testing of the entire stator unit. As disadvantageously, however, it should be noted here that a subsequent repair of the Stator plates hidden electrical components (Hall sensors, possibly other Components) is not possible without removing the stator winding.

Embodiments of the invention are explained below with reference to the drawings. It show in a schematic representation:

Fig. 1 shows the cross-section of a motor or magnetic bearing with an integrated circuit board,

Fig. 2 is a plan view of a printed circuit board, the wirings between the components the sake of simplicity not drawn in,

Fig seen the three-dimensional view of a printed circuit board cut-out with eddy current and Hall sensor of the air gap side. 3, wherein the simplicity of the circular printed circuit board inner contour and the circular conductors of the coils run marked stretched half,

Fig. 4 shows the cross section of a motor or magnetic bearing with an integrated circuit board with the extension with respect to FIG. 1 about an axial eddy current sensor unit

Fig. 5 shows an example for increasing the cross sectional area of the eddy current sensor and to improve the long-distance effect of the magnet field through the coil of an additional printed circuit board,

Fig. 6 shows an example for the integration of electrical components in the Statorblecheinheit with the possibility of a good heat dissipation particularly in power semiconductors,

Fig. 7 various alternatives to arrangement of the eddy current sensor coils on the (s) of printed circuit boards,

Fig. 8 is a cross section of a motor or magnetic bearing with an integrated circuit board and a non-ferromagnetic intermediate layer in the rotor,

Fig. 9 shows an embodiment of an eddy current sensor for a multi-groove engine.

Fig. 1 shows the cross section of an electromagnetic energy converter with an integrated circuit board. The energy converter can be implemented, for example, as a motor in various designs (e.g. inside, outside, disc rotor, linear motor), as a bearingless motor or as an active magnetic bearing (e.g. axial, radial bearing). According to the invention, the printed circuit board ( 3 ) is arranged in one plane between the winding heads ( 1 , 5 ) of the stator ( 7 ), here in the middle of the stator laminated core. Depending on the application, one or more circuit boards can be inserted symmetrically or asymmetrically in the intermediate layers of the stator laminated core.

In the illustration of Fig. 2, the board contour (19) up to the region of the plug connecting lug corresponding to (59) of the contour of the laminated core. However, this is not absolutely necessary. However, the cutout for the passage of the winding strands ( 8 ) in the area of the slots ( 9 ) and possibly also in the area of the fastening openings ( 10 , 49 ) is imperative.

When fastening the circuit board ( 3 ) in the stator ( 7 ), make sure that the conductor guides and electrical components are not short-circuited via the ferromagnetic stator parts ( 2 , 4 ). Possible precautions are spacers in the form of insulating films ( 16 , 17 ) with punched-out areas in the area of the components, the coating ( 16 , 17 ) of the ferromagnetic bodies or the printed circuit board surfaces ( 16 , 17 ) or also maintaining sufficient air gaps between the printed circuit board and the laminated cores by placing the printed circuit board ( 3 ) on spacers or sleeves.

As can be seen from Fig. 2, various electrical components are placed on the circuit board. This can, for example components for the sensors (11, 12, 13), the sensor electronics (14), the signal electronics (14), the power electronics (20) or the drive for the electrical connection (15). The individual assemblies are only indicated symbolically in the drawing by arbitrarily selected and placed components. The components can be arranged both in the area of the stator teeth, the stator yoke or, if the printed circuit board projects beyond the stator parts, outside the stator contour.

The possibility of a simple implementation of eddy current sensors ( 12 ) via the circuit board layout with the aid of conductor track sections ( 21 ) and plated-through holes ( 22 ) should be particularly emphasized. An eddy current sensor can consist of several coils that are connected in series or in parallel. Examples of such groups of coils are shown in Fig. 3, Fig. 5 and Fig. 7. In this case, both groups having the same field orientation (35, 36, 52, 53, 57, 58) as well as groups with alternating polarity (50, 51 55 , 56 and 57 , 58 ) if the connections of a coil are interchanged. The subdivision into individual coils ( 35 , 36 , 52 , 53 , 57 , 58 ) in the same direction can be particularly useful if, as in FIG. 2, other components are also to be placed near the air gap. Otherwise it is advisable to implement a larger single coil ( 54 ) due to the lower resistance and the lower number of vias. In the illustrations of FIGS. 5 and 7 is shown symbolically only one turn of the coil. As a rule, however, the coils are provided with several turns one behind the other. In order to achieve higher coil cross-sectional areas and thus higher inductance values, the circuit board thickness can be varied in commercially available steps (e.g. 1.6 mm, 2.4 mm, 3.2 mm). This also increases the thickness in areas outside the eddy current sensors, where an increase is not necessary or maybe even not desired at all. In critical cases, a second printed circuit board can therefore be placed in a restricted partial area (at least in the area of the eddy current sensors), as shown in FIGS. 5 ( 3 , 32 ) and 7 ( 3 ; 32 ). Just as with the arrangement of the coils in the transverse direction, the polarity of the coils can be selected in the same direction ( 35 , 36 ) or in opposite directions ( 55 , 56 ). In order to avoid short circuits, insulating spacers ( 31 ) can also be used to separate the printed circuit boards. With the selection of coil configurations ( 12 , 29 , 30 , 27 , Fig. 5, Fig. 7), both radial and axial distance measurements can be carried out. It is crucial that a radial field component is available for the radial measurement and an axial field component of the coil for the axial measurement. In all cases, the eddy current sensor must face an electrically conductive surface on the rotor, which weakens as the sensor approaches the magnetic field. This influence affects the behavior of the eddy current capacitor resonant circuit and can provide information about the travel distance between sensor and rotor via an evaluation circuit. Electrically conductive surfaces can e.g. B. in the form of a metal ring, a metal disc or by metallic coating of rotor parts. Examples of radial sensors can be found in FIGS. 2, 3, 5 and the top four illustrations in FIG. 7. Fig. 4 and the lower figure in Fig. 7 show versions of axial sensors. A radial overlap of the printed circuit board and the rotor has proven to be advantageous for this. In the example from FIG. 7, two metallic layers ( 60 ) are introduced into the rotor to improve the sensor sensitivity. In many cases, the conductivity of the ferromagnetic bodies ( 61 , 62 ) is already sufficient.

In practice, four eddy current sensors, each arranged at an angle of 90 degrees, have proven useful for detecting the position of the rotor. For such an arrangement, four sensor coil pairs placed on different legs are exemplified in the drawing. If the electromagnetic energy converter consists of a larger number of legs or teeth, the coils of a single eddy current sensor can also be placed on different legs or teeth. To increase the coil inductance and thus to improve the characteristic of the eddy current sensor capacitor resonant circuit, one or more ferrite bodies ( 44 ) can be arranged in the near field of the coils. These are advantageously placed in a corresponding recess (similar to 43 ) in the printed circuit board. In order to achieve the highest possible electrical sensitivity, the vortex sensor coils should be placed as close as possible to the air gap ( 18 ).

Magnetic field sensors ( 11 ) can also be very easily integrated into the circuit board structure. They can advantageously be inserted in recesses ( 43 ) in the printed circuit board ( 3 ) in the vicinity of the air gap ( 18 ). The measurement of the flux density allows a statement about the angular position of the rotor, particularly in the case of permanent magnet motors. In the case of a circuit board arrangement with one or two adjacent ferromagnetic bodies, it proves to be very favorable that the armature field in the area of the Hall sensor is very weak. In contrast to this, the permanent magnetic field to be measured is comparatively strong when the sensor is attached in the circuit board near the air gap.

When using SMD components, it is possible to hang the components ( 11 ) via the contact pins ( 45 ) in the recesses ( 43 ) and to solder the connections to the corresponding contact pads. Components with a vertical field measurement direction can be tilted in the recess and soldered to the top and bottom of the circuit board. The arrangement of FIG. 3 is particularly suitable for components with a horizontal measuring direction.

In contrast to the drawing proposal in Fig. 2, it may be beneficial to replace the pair of coils ( 12 ) of one leg by a large coil with long conductor tracks and to attach the magnetic field sensor to the side of the coil, right or left.

Furthermore, a simple possibility of stator temperature detection is to be shown. This can be done using electrical resistors with, for example, meandering conductor tracks ( 13 ). The temperature-dependent change in resistance is measured and evaluated using appropriate electronics.

Other coil arrangements are possible on the circuit board, such as coils for Measurement of the speed and the angular position via the induced voltage when moving Rotor. However, further enumerations and statements should not be made here To be received.

In order to keep the axial length of the energy converter as small as possible, projecting components ( 14 , 20 ) can be immersed in recesses ( 42 ) in the ferromagnetic body ( 2 , 4 ). The realization of the corresponding cutouts can be integrated in the punching process in the case of sheet metal packages and in the pressing process in the case of powder composite materials. For power semiconductor components, there is even the possibility of filling the remaining cavity with a thermal paste ( 41 ) and thus creating a good heat transfer to the ferromagnetic body.

Fig. 8 shows an arrangement of the electrical energy converter, in which the rotor is divided into three layers. The outer layers are formed by two permanent magnet rotors made of ferromagnetic bodies ( 63 , 64 ) and permanent magnets ( 64 , 65 ), the middle layer is a non-ferromagnetic material ( 66 ), such as aluminum, plastic or an air space. Magnetic restoring forces are formed between the opposing permanent magnet rotor disks and stator disks ( 2 , 4 ) when the rotor is displaced from the axial center. These are reinforced by the introduction of the intermediate layer ( 66 ) as a result of the resulting field concentration. The characteristic of the passive axial bearing is thus improved and the stability is increased.

In Fig. 9 a possible implementation example for the sensor arrangement in a motor vielnutigen is cited. A total of four eddy current sensors ( 77 , 78 , others not shown) and also four Hall sensors ( 72 , 79 , others not shown) are accommodated on the circuit board. An eddy current sensor ( 77 ) consists of 5 individual coils ( 67 , 68 , 69 , 70 , 71 ) each with several turns (not shown) similar to the coil ( 12 ) from FIG. 2. The individual coils are connected in series via the line connections ( 76 ) connected to an eddy current sensor. For the sake of simplicity, the contact connections ( 73 , 74 ; 75 ) end blind in the drawing. Of course, these connections can be fed directly to a connector similar to ( 15 ) or to electronics ( 14 ) which is also housed on the circuit board.

Claims (17)

1. Electromagnetic energy converter, in particular brushless motors, motors with integrated magnetic bearing winding or magnetic bearing, comprising a stator with at least one phase winding, a moving part, in particular a rotor, and at least one printed circuit board for the placement and electrical connection of electrical components, characterized in that that at least one of the printed circuit boards ( 3 ) is mounted in a plane between the winding heads ( 1 , 5 ) of the stator ( 7 ) of the electromagnetic energy converter. 2. Electromagnetic energy converter according to claim 1, characterized in that the circuit board ( 3 ) between two ferromagnetic molded bodies ( 2 , 4 ), in particular between two sheet metal, iron powder composite or ferrite packages, is attached. 3. Electromagnetic energy converter according to one of the preceding claims, characterized in that the contour ( 19 ) of the printed circuit board ( 3 ) roughly follows the contour of the winding support or the ferromagnetic molded body ( 2 , 4 ) in partial areas, so that slot openings ( 9 ) or bores ( 10 ) for fasteners in these bodies can not be blocked by the circuit board ( 3 ). 4. Electromagnetic energy converter according to one of the preceding claims, characterized in that the circuit board by appropriate spacers, such as insulation films ( 16 , 17 ), disks, coatings ( 16 , 17 ) of the ferromagnetic molded body ( 2 , 4 ) or the circuit board ( 3 ) itself, electrically separated from the stator parts ( 2 , 4 ) of the energy converter, such as the laminated cores or the windings. 5. Electromagnetic energy converter according to one of the preceding claims, characterized in that the circuit board with electrical components ( 11 , 12 , 13 , 14 ), in particular with sensors ( 11 , 12 , 13 ) for detecting mechanical, electrical or thermal variables, one Signal electronics ( 14 ) for amplifying and evaluating the sensor signals, signal electronics ( 14 ) for controlling or regulating the energy converter; power electronics ( 20 ) for controlling the windings ( 8 ) of the energy converter and plug connections ( 15 ). 6. Electromagnetic energy converter according to one of the preceding claims, characterized in that on the circuit board ( 3 ) at least one eddy current sensor ( 12 ), which is particularly for measuring distances or angles between the stator ( 7 ) and the moving part ( 6 ) of the Suitable energy converter, is integrated in such a way that with the help of conductor track sections ( 21 ) and possibly through-contacts ( 22 ) a magnetic coil is formed with a preferably radial winding axis ( 23 ), which builds up a magnetic alternating field by appropriate excitation, which in particular radially in penetrates the air gap ( 18 ) of the energy converter and thus allows a measurement of the radial position of the moving body ( 6 ). 7. Electromagnetic energy converter according to one of the preceding claims, characterized in that at least one surface ( 24 , 25 ) of the circuit board ( 3 ) is covered by a part ( 26 ) of the rotor ( 6 ) and that on the circuit board ( 3 ) in In this covered area there is at least one eddy current sensor ( 27 ) constructed according to one of the preceding claims, preferably with an axial winding axis ( 28 ), the magnetic field of which, in particular, penetrates axially into the air gap of the energy converter and thus allows the axial position of the moving body to be measured. 8. Electromagnetic energy converter according to one of the preceding claims, characterized in that an eddy current sensor ( 12 , 77 ) from one or more series or parallel interconnected coils ( 29 , 30 , 67 , 68 , 69 , 70 , 71 ) is composed. 9. Electromagnetic energy converter according to one of the preceding claims, characterized in that on the circuit board ( 3 ), optionally separated by an electrical insulating layer ( 31 ), a second circuit board ( 32 ) with at least one eddy current coil ( 33 ) is located, namely not necessarily, but preferably so that the eddy current coils of the two printed circuit boards ( 3 , 32 ) are arranged one above the other and electrically connected to one another in order to enlarge the active coil area ( 34 ) of the eddy current sensor and thus a greater long-range effect of the magnetic field ( 35 , 36 ) achieve. 10. Electromagnetic energy converter according to one of the preceding claims, characterized in that the circuit board ( 3 ) is equipped with at least one magnetic field sensor ( 11 ), in particular a Hall sensor, which is in particular about the measurement of the magnetic field ( 37 ) between the stator and the moving Part of the energy converter is suitable for indirect measurement of distances or angles between the stator and the moving part. 11. Electromagnetic energy converter according to one of the preceding claims, characterized in that on the circuit board ( 3 ) at least one temperature sensor ( 13 ) is integrated, which is either equipped as an external component on the circuit board, or in the form of conductor tracks ( 38 ) the printed circuit board ( 3 ) forms an electrical resistance, the change in resistance of which can be measured via appropriate electronics ( 14 ) and provides information about the temperature profile in the energy converter. 12. Electromagnetic energy converter according to one of the preceding claims, characterized in that the sensors for measuring distances or angles are located on the edge region ( 39 ) of the printed circuit board ( 3 ) bordering the air gap of the energy converter. 13. Electromagnetic energy converter according to one of the preceding claims, characterized in that in at least one ferromagnetic body ( 2 ) there is at least one free space ( 42 ) into which at least one component ( 40 ) mounted on the printed circuit board ( 3 ) can protrude without that there is an electrical contact between the electrical component ( 40 ) and the ferromagnetic body ( 2 ). 14. Electromagnetic energy converter according to one of the preceding claims, characterized in that the free spaces ( 42 ) with an electrically insulating but thermally highly conductive means ( 41 ) are filled or filled in order to ensure sufficient heat transfer between the electrical component projecting into the free space ( 40 ) and the ferromagnetic body ( 2 ). 15. Electromagnetic energy converter according to one of the preceding claims, characterized in that there are free spaces ( 43 ) in the circuit board in which the components ( 11 ), in particular electrical or magnetic components, such as Hall sensors or ferrite cores ( 44 ), can protrude, in particular in the way that in electrical components at the edges of the free spaces on the surface of the circuit board ( 3 ) contacting options ( 45 ) are provided for the electrical component. 16. Electromagnetic energy converter according to one of the preceding claims, characterized in that the rotor is constructed from a plurality of disk-like layers ( 46 , 47 , 48 ), with a non-ferromagnetic layer ( 47 ) between two ferromagnetic or permanent magnetic layers ( 46 , 48 ), which faces the printed circuit board ( 3 ) in order to bring about a greater magnetic retraction force in the event of a possible axial deflection of the rotor. 17. Electromagnetic energy converter according to one of the preceding claims, characterized in that there are recesses in the circuit board such as bores ( 10 ), notches ( 49 ) or edges, which are for positioning the circuit board ( 3 ) to the stator ( 7 ) and, if appropriate also, if the stator parts are directly or indirectly attached to the circuit board, are suitable for mounting the circuit board and thus the stator in one device.