Method for calculating the position of a conductor track on a printed circuit board, rotary transformer rotor, electric rotary transformer for inductive energy transmission and separately excited electric synchronous machine

Abstract

Method for calculating the position of a conductor track on a printed circuit board, wherein the conductor track forms a secondary coil of a rotary transformer rotor for a rotary transformer, the method comprising the following measures: a) Providing a printed circuit board (2) which, in a top view, has the geometry of an annulus, b) Calculating the center of gravity (CG) of a conductor track (4) which in plan view has the geometry of a spiral (5) and spirals around the center point (MP) of the printed circuit board (2) with several turns (3), wherein the position of the center of gravity (CG) relative to the center point (MP) of the circular ring (CR) is calculated, c) Determining the position of the conductor track (4) forming the secondary coil of the rotor on the printed circuit board (2) taking into account the center of gravity (SP) of the conductor track (4) determined in measure b) such that the center of gravity (SP) of the spiral conductor track (4) and the center point (MP) of the annular printed circuit board (2) coincide.

Description

[0001] The invention relates to a method for calculating the position of a conductor track on a printed circuit board, wherein the conductor track forms a secondary coil of a rotary transformer rotor for a rotary transformer. The invention further relates to a rotary transformer rotor, which is preferably manufactured using this method. The invention also relates to a rotary transformer with such a rotary transformer rotor and to a separately excited synchronous electric machine with such a rotary transformer.

[0002] So-called separately excited synchronous machines require a direct current in their rotary transformer rotor to generate the magnetic rotor field. This process is called "rotor excitation." The electrical current is preferably transferred to the rotating rotary transformer rotor inductively, i.e., wirelessly. Such a configuration, as part of a separately excited synchronous machine, is also referred to as a "rotary transformer" or "rotating planar transformer."

[0003] The operating principle of said inductive voltage or energy transmission is based on an electrical transformer, with the primary winding or primary coil of the transformer arranged on the rotary transformer stator of the rotary transformer or synchronous machine, and the secondary winding or secondary coil arranged on the rotating rotary transformer rotor. The secondary coil can be arranged on a circular circuit board of the rotating rotary transformer rotor. A spiral geometry of the conductor track (as viewed from above) with a spiral encircling the center of the circuit board has proven to be advantageous for efficient inductive coupling.

[0004] Against this background, DE 20 2014 101 753 U1 discloses an optoelectronic sensor for detecting objects. The sensor comprises two transmission units that can be rotated relative to each other and, in turn, have circuit boards in which a primary and secondary coil, respectively, are integrated in the form of a respective conductor track.

[0005] DE 10 2013 010 578 A1 describes a rotary transformer for the contactless transmission of electrical energy, comprising two rotary transformer parts arranged so as to rotate relative to one another. A first rotary transformer part comprises a primary winding, and a second rotary transformer part comprises a secondary winding for inductive energy transmission. Both windings are designed as toroidal windings.

[0006] US 2017 / 0 213 639 A1 discloses a planar coil formed by a conductor track with a spiral geometry.

[0007] What proves to be problematic is that due to the spiral geometry of the conductor track, this creates an undesirable imbalance when the circuit board rotates.

[0008] It is therefore an object of the present invention to provide an improved embodiment for a rotary transformer in which this problem no longer occurs.

[0009] This object is achieved by the subject matter of the independent patent claims. Preferred embodiments are the subject matter of the dependent patent claims.

[0010] The basic idea of ​​the invention is therefore to consider the center of gravity of the spiral conductor track when laterally positioning the conductor track on the circular circuit board. To this end, it is proposed to first estimate the center of gravity of the spiral conductor track relative to the center of the circuit board, or relative to the origin of the spiral forming the conductor track, as accurately as possible. This allows, in a subsequent step, to position the conductor track on the circuit board so that its center of gravity coincides with the center of the conductor track. This, in turn, ensures that the conductor track no longer generates an imbalance when the circuit board rotates.

[0011] The method according to the invention is used to calculate the position of a conductor track on a printed circuit board, wherein the conductor track forms a secondary coil of a rotary transformer rotor for a rotary transformer. The method according to the invention comprises three measures a), b), and c). According to measure a), a printed circuit board is provided which, in a plan view, has the geometry of a circular ring, wherein the circular ring has a center point. The center point is expediently arranged on a rotation axis of the printed circuit board when used in a rotary transformer. In measure b), the center of gravity of a conductor track is calculated which, in a plan view of the printed circuit board, has the geometry of a spiral and spirals around the center point of the circular ring. Expediently, the center of gravity is calculated relative to the center point of the circular ring under the assumption that the origin of the spiral is arranged at this center point.In step c), the position of the conductor track forming the secondary coil on the circuit board is then determined. This determination of the circuit board position takes into account the center of gravity determined in step b). According to the invention, the center of gravity is taken into account in such a way that the center of gravity of the spiral-shaped conductor track and the center of the circular circuit board coincide in a top view of the circuit board.

[0012] According to a preferred embodiment, based on the center of gravity of the spiral conductor track calculated in step b), a positional deviation of the center of gravity from the center of the circular circuit board or from the origin of the spiral describing the conductor track is calculated. In both variants, when determining the position of the conductor track according to step c), the center of the spiral is offset from the center of the circular ring on the circuit board by the positional deviation. The offset is performed such that the center of gravity of the spiral conductor track and the center of the circular circuit board coincide, so that both are expediently arranged on the rotation axis around which the circuit board with the conductor track can be produced.

[0013] According to an advantageous further development, in order to calculate the center of gravity, the circuit board is divided into quadrants of a coordinate system that follow one another along the circumferential direction, the origin of which is located at the center of the circuit board. The circuits of the spiral conductor track are divided into conductor track sections that follow one another along the circumferential direction of the circuit board, so that exactly one conductor track section is arranged in each quadrant. The center of gravity of the conductor track section arranged in this quadrant can then be calculated for each quadrant. The center of gravity of the entire conductor track can then be calculated from the centers of gravity of the individual conductor track sections. This variant allows the inherently relatively complicated calculation of the center of gravity of a spiral to be simplified in a relatively simple way by separating the individual conductor track sections with regard to the determination of their respective centers of gravity.

[0014] Particularly preferably, the center of gravity of the spiral-shaped conductor track can then be calculated by averaging the conductor track sections assigned to the individual quadrants. Such averaging is mathematically very simple if the centers of gravity of the individual conductor track sections are known. Particularly preferably, the arithmetic mean can be calculated.

[0015] It is particularly useful to calculate the center of gravity of the spiral conductor track from the respective center of gravity of the conductor track sections assigned to the individual quadrants according to the following equation: XSP=mQ1∗XSP1+mQ2∗XSP2+…+mn∗XSPnmspiral YSP=mQ1∗YSP1+mQ2∗YSP2+…+mn∗YSPnmspiral

[0016] Here, m Qi the mass of the conductor track section in quadrant Q i , X SPi the X-coordinate of the center of gravity SP iof the i-th conductor section in the i-th quadrant, Y SPi the Y-coordinate of the center of gravity SP i of the i-th conductor section in the i-th quadrant Q i and m spiral the total mass of the spiral conductor track, i.e. all conductor track sections.

[0017] To calculate the center of gravity of a particular track section in each quadrant, this track section can be approximated by a quarter circle. This procedure allows a simple but very good approximation of the value of the center of gravity of a spiral 90° segment of the track arranged in a quadrant, which is relatively complicated to calculate.

[0018] It is useful to use the X and Y coordinates X SPi , Y SPi of the center of gravity of the conductor track section in the i-th quadrant is calculated according to the following relationship: XSPi=YSPi=2Rπ where R is the radius of the track in the i. quadrant measured from the center MP of the quarter circle or from the center of the circuit board.

[0019] The invention further relates to a rotary transformer rotor for a rotary transformer, which is manufactured using the inventive method presented above. The advantages of the inventive method are transferred in this case to the inventive rotary transformer rotor. The rotary transformer rotor comprises a printed circuit board, which has the geometry of a circular ring in a plan view. At least one conductor track is arranged on the printed circuit board, which spirals around the center of the circular ring. The center of the spiral conductor track is offset from the center of the circular ring such that the center of gravity of the spiral conductor track and the center of the circular ring-shaped printed circuit board coincide in a plan view of the printed circuit board.In the context of the present invention, "arranged on the secondary coil circuit board" means that the at least one conductor track forming the secondary coil is arranged—in particular visibly—on the surface of the circuit board or—in particular invisibly—surrounded by the material of the circuit board. A combination of both variants, as can be used particularly in multilayer circuit boards, is also encompassed by the above formulation.

[0020] The invention further relates to an electrical rotary transformer for inductive energy transmission. The rotary transformer comprises a primary coil with a rotary transformer stator. The rotary transformer also comprises a rotary transformer rotor according to the invention, which is rotatable about a rotation axis relative to the rotary transformer stator and has a secondary coil. The advantages of the rotary transformer rotor according to the invention are therefore transferred to the rotary transformer according to the invention. The center point of the circuit board and the center of gravity of the conductor track are arranged on the rotation axis. Furthermore, the secondary coil is formed by the conductor track arranged on the circuit board of the rotary transformer. For this purpose, the secondary coil or conductor track can be or is inductively coupled to the primary coil.

[0021] The invention further relates to a separately excited synchronous electric machine. The synchronous machine comprises an electrically energizable synchronous machine stator for generating a magnetic stator field. The synchronous machine further comprises an electrically energizable synchronous machine rotor, which is rotatable relative to the synchronous machine stator and generates a magnetic rotor field, and which has a synchronous machine rotor shaft. Furthermore, the synchronous machine comprises an electrical rotary transformer according to the invention, which is rotationally fixedly connected to the synchronous machine rotor shaft. The advantages of the rotary transformer according to the invention are therefore transferred to the electrical synchronous machine according to the invention.

[0022] The advantages of the rotary transformer according to the invention presented above are therefore also transferred to the separately excited electrical synchronous machine according to the invention.

[0023] In particular, the synchronous machine is used as a traction motor, for example in a motor vehicle.

[0024] Further important features and advantages of the invention emerge from the subclaims, from the drawings and from the associated description of the figures based on the drawings.

[0025] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0026] Preferred embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally identical components.

[0027] They show, schematically: Fig. 1 an example of a conventional rotary transformer rotor, Fig. 2a-2e several representations illustrating the division of the circuit board into several conductor track sections, Fig. 3 a diagram illustrating the calculation of the center of gravity of a quarter circle, Fig. 4 shows the position of the conductor track on the printed circuit board before the correction of the center of gravity position carried out by means of the method according to the invention, Fig. 5 the position of the conductor track on the circuit board after the correction of the center of gravity position carried out by means of the method according to the invention.

[0028] Fig. 1 illustrates an example of a conventional rotary transformer rotor 1'. This comprises a circuit board 2', which, in the top view shown, has the geometry of a circular ring KR'. A conductor track 4* with the geometry of a spiral 5' is arranged on the circuit board 2'. The conductor track 2' spirals around the center point MP' of the circular ring KR' with several revolutions 3'. An origin U' of the spiral 5 is identical to the center point MP'. In the top view shown, the center of gravity SP' of the spiral conductor track 4' and the center point MP' of the circular circuit board 2 are not identical - as a result of the spiral geometry of the conductor track 4'. In other words, the center point MP' and the center of gravity SP' do not coincide in the top view shown.However, this has the consequence that when the circuit board 2' rotates around the center point MP' as the axis of rotation D', a not insignificant undesirable imbalance can occur, especially at high rotational speeds.

[0029] The method according to the invention is explained below by way of example. Using the method, as in the example of Fig. 1, a conductor track 4 with a spiral geometry can be created. However, the conductor track 4 positioned on the circuit board 2 by means of the method according to the invention does not generate any imbalance when the circuit board 2 rotates.

[0030] The process comprises three steps a), b) and c). According to step a), a printed circuit board is first manufactured as described in Fig. 2a shown conductor track 3). The circuit board 2 has analogous to the circuit board 2' according to Fig. 1 shows the geometry of a circular ring.

[0031] According to measure b), the center of gravity SP of a conductor track 4 having the geometry of a spiral 5 and spiraling around the center MP of the circular printed circuit board 2 with several revolutions 3 is calculated. For this purpose, the position of the center of gravity SP (not shown) is calculated relative to the center MP of the circular printed circuit board 2. Furthermore, it is assumed that the origin U of the spiral 5 is located at the center MP of the circular ring KR.

[0032] To calculate the center of gravity SP, the circuit board 2 is divided into quadrants Q1, Q2, ..., Q n of a coordinate system whose origin U is located at the center MP. The successive circuits 3 of the spiral conductor track 4 are divided into successive conductor track sections 6.1, ..., 6.n along the circumferential direction of the printed circuit board 2, so that in each quadrant Q1, Q2, ..., Q na conductor track section 6.1, ..., 6.n is arranged.

[0033] In the Fig. 2a, the first conductor track section 6.1 located in the first quadrant Q1 is marked. Accordingly, in the Fig. 2b to 2e, the conductor track sections 6.2 to 6.5 arranged in the second to fifth quadrants Q1 to Q5 are marked. In the example, for each quadrant Q1, Q2, ..., Q n the focus SP1, SP2, ..., SP n of this quadrant Q1, Q2, ..., Q n arranged conductor track section 6.1, 6.2, ..., 6.n is calculated. From the centers of gravity SP1, SP2, ..., SP n of the individual conductor track sections 6.1, 6.2, ..., 6.n, the center of gravity SP of the entire conductor track 4 is then calculated.

[0034] The center of gravity SP of the spiral conductor track 3 can be determined by averaging the centers of gravity SP1, SP2, ..., SP n which represents the individual quadrants Q1, Q2, ..., Q nassigned conductor track sections 6.1, ..., 6.n are calculated. For the calculation of the center of gravity SP i of a respective conductor track section 6.1, 6.2, ..., 6.n, this conductor track section 6.1, 6.2, ..., 6.n can be approximated by a quarter circle (cf. Fig. 2a-2e). The X-coordinates X SP1 , X SP2 , ..., X SPn and the Y coordinates Y SP1 , Y SP2 , ..., Y SPn the focus areas SP1, SP2, ..., SP n of the individual conductor track sections 6.1, 6.2, 6.n or the individual quadrants Q1, Q2, ..., Qn can be calculated according to the following relationship, which is also shown in Fig. 3 is illustrated, can be calculated: XSPi=YSPi=2Rπ

[0035] Here, R is the radius of the conductor track 4 or the conductor track section 6.i in the i-th quadrant, measured from the center point MPKR of the circular ring KR.

[0036] From the center of gravity coordinates X SPi , Y SPithe focus areas SP1, SP2, ..., SP n of the individual conductor track sections 6.1, 6.2, ..., 6.n or the individual quadrants Q1, Q2, ..., Q n the X-coordinate X SP and the Y coordinate Y SP of the center of gravity SP of the entire conductor track 4, i.e. all conductor track sections 6.1, ..., 6.n, is calculated according to the following equation: XSP=mQ1∗XSP1+mQ2∗XSP2+…+mn∗XSPnmspiral YSP=mQ1∗YSP1+mQ2∗YSP2+…+mn∗YSPnmspiral

[0037] Here, m Qi the mass of the conductor section 6.i in the i-th quadrant. Furthermore, X SPi the X-coordinate of the center of gravity SP i of the conductor track section 6.i of the i. quadrant. Furthermore, Y SPi the Y-coordinate of the conductor track section 6.i of the i. quadrant. Finally, m spiralthe total mass of the spiral conductor track 2, i.e. all conductor track sections 6.1, 6.2, ..., 6.n. Thus, the arithmetic mean of the coordinates of the individual centers of gravity SPi is calculated.

[0038] In step c) of the method, the position of the conductor track 4 forming the secondary coil of the rotor on the printed circuit board 2 is determined, taking into account the center of gravity SP of the conductor track 4 determined in step b), such that the center of gravity SP of the spiral conductor track 4 and the center point MP of the annular printed circuit board 2 coincide in a plan view of the printed circuit board 2. For this purpose, a positional deviation of the center of gravity SP from the center point MP can be calculated in x and y coordinates. When determining the final position of the conductor track 4 on the printed circuit board 2 according to step c), the origin U of the spiral 5 is arranged on the printed circuit board 2 offset by the positional deviation from the center point MP of the annular printed circuit board 2. Thus, the center point MP and the center of gravity SP coincide.

[0039] To illustrate, the Fig. 4 and Fig.5 shows the position of the conductor track 4 on the printed circuit board 2 before and after the correction of the center of gravity position carried out using the method according to the invention. It can be seen that before application of the method according to the invention, the origin U' of the spiral conductor track 4 and the center point MP' of the printed circuit board 2 (and thus its axis of rotation D') are identical, but these positions deviate from the position of the center of gravity SP' of the conductor track 4. After application of the method, due to the displacement of the conductor track 4 by the position deviation calculated above, the center of gravity SP, the center point MP, and the axis of rotation D are identical, but all three are different from the origin U of the conductor track 4.

Claims

[1] A method for calculating the position of a conductor track on a printed circuit board, the conductor track forming a secondary coil of a rotary transformer rotor for a rotary transformer, the method comprising the following measures: a) providing a printed circuit board (2) which has the geometry of a circular ring in a plan view, b) Calculating the center of gravity (SP) of a conductor track (4) which, in plan view, has the geometry of a spiral (5) and circulates spirally around the center (MP) of the printed circuit board (2) with several revolutions (3), wherein the position of the center of gravity (SP) is calculated relative to the center (MP) of the circular ring (KR), c) Determining the position of the conductor track (4) forming the secondary coil of the rotor on the printed circuit board (2) taking into account the center of gravity (SP) of the conductor track (4) determined in measure b) such that the center of gravity (SP) of the spiral-shaped conductor track (4) and the center point (MP) of the annular printed circuit board (2) coincide. [2] Method according to claim 1, characterized by that in measure b) an origin (U) of the spiral (5) is arranged in the center point (MP) of the printed circuit board (2). [3] Method according to claim 1 or 2, characterized by that on the basis of the center of gravity (SP) of the spiral conductor track (2) calculated in measure b), a positional deviation of the center of gravity (SP) from the center point (MP) is calculated and that when determining the position of the conductor track (4) according to measure c), the origin (U) of the spiral (5) is arranged on the circuit board (2) offset by the positional deviation from the center point (MP) of the circuit board (2). [4] Method according to one of claims 1 to 3, characterized by , that - for the calculation of the center of gravity (SP): the circuit board (2) is divided into successive quadrants (Q1, Q2, ..., Q n ) of a coordinate system (KS) whose origin (U) is located at the center (MP) of the printed circuit board (2), - the circuits of the spiral conductor track (4) are divided into conductor track sections (6.1, 6.2, ..., 6.n) following one another along the circumferential direction of the printed circuit board (2), so that in each quadrant (Q1, Q2, ..., Q n ) a conductor track section (6.1, 6.2, ..., 6.n) is arranged, for each quadrant (Q1, Q2, ..., Q n ) the center of gravity (SP1, SP2, ..., SP n ) of the energy in this quadrant (Q1, Q2, ..., Q n ) arranged conductor track section (6.1, 6.2, ..., 6.n) is calculated, - from the main areas (SP1, SP2, ..., SP n) of the individual conductor track sections (6.1, 6.2, ..., 6.n) the center of gravity (SP) of the entire conductor track (4) is calculated. [5] Method according to claim 4, characterized by that the center of gravity (SP) of the spiral conductor track (3) is determined by averaging the centers of gravity (SP1, SP2, ..., SPn) of the individual quadrants (Q1, Q2, ..., Q n ) assigned conductor track sections (6.1, 6.2, ..., 6.n). [6] Method according to claim 4 or 5, characterized by that the center of gravity (SP) of the spiral conductor track (4) is used to calculate the mean value from the respective center of gravity (SP1, SP2, ..., SP n ) that represents the individual quadrants (Q1, Q2, ..., Q n ) assigned conductor track sections (6.1, 6.2, ..., 6.n) is calculated according to the following equation: XSP=mQ1∗XSP1+mQ2∗XSP2+…+mn∗XSPnmspiral YSP=mQ1∗YSP1+mQ2∗YSP2+…+mn∗YSPnmspiral where m Qiis the mass of the i-th track section in the i-th quadrant and X SPi the X-coordinate of the center of gravity SP i of the track section of the i-th quadrant and Y SPi the Y-coordinate of the center of gravity SP i of the i-th conductor section of the i-th quadrant and m spiral is the total mass of the spiral conductor track (4), i.e. of all conductor track sections (6.1, 6.2, ..., 6.n). [7] Method according to claim 6, characterized by that for the calculation of the center of gravity (SP i ) of a respective conductor track section (6.i) this conductor track section (6.i) is approximated by a quarter circle [8] Method according to claim 6 or 7, characterized by , that the X and Y coordinates (X SPi , Y SPi ) of the center of gravity (SPi) can be calculated according to the following relationship: XSPi=YSPi=2Rπ where R is the radius (R) of the conductor track in the i-th quadrant (Q i ) is. [9] Rotary transformer rotor (1) for a rotary transformer, manufactured by the method according to one of the preceding claims, - with a printed circuit board (2) which has the geometry of a circular ring in a plan view, - with a conductor track (4) arranged on the circular printed circuit board (2) and spiraling around the center point (MP) of the circular ring, - wherein in the plan view the origin (U) of the spiral conductor track (2) is offset from the center point (MP) of the annular conductor track (2) in such a way that the center point (SP) of the spiral conductor track (4) and the center point (MP) of the annular printed circuit board (2) coincide in the plan view of the printed circuit board (2). [10] Electrical rotary transformer for inductive energy transmission, - with a rotary transformer stator having a primary coil, - with a rotary transformer rotor (1) according to claim 9, which is designed to be rotatable about an axis of rotation relative to the rotary transformer stator and has a secondary coil, - wherein the center point (MP) of the circular printed circuit board (2) and the center of gravity (SP) of the conductor track (4) are arranged on the axis of rotation (D), - wherein the secondary coil is formed by the conductor track (4) arranged on the circuit board (2) of the rotary transformer and can be or is inductively coupled to the primary coil, [11] Separately excited electrical synchronous machine, in particular traction motor, - with an electrically energizable synchronous machine stator for generating a magnetic stator field, - with an electrically energizable synchronous machine rotor which is rotatable relative to the synchronous machine stator for generating a magnetic rotor field, which has a synchronous machine rotor shaft, - with an electrical rotary transformer according to claim 10, which is connected in a rotationally fixed manner to the synchronous machine rotor shaft.

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