Electric motor with an electronic assembly

Abstract

Electric motor (32) with an electronic assembly (33), wherein the electric motor (32) has two or more coils (2 - 4), wherein the coils (2 - 4) of the electric motor (32) are arranged in a so-called star connection, wherein the star point (13, 24, 36) of the star connection is designed to be contacted, wherein the electronic assembly (33) has an electrical return (27), wherein the star point (13, 24, 36) is connected to a phase line by means of the electrical return (27), so that the motor circuit diagram has the form of a Wheatstone bridge, wherein two components are present, wherein a first component (21) has a first impedance (Z CM ), wherein a second component (20) has a second impedance (Z YCK ), wherein the electrical return (27) connects the star point (13, 24) to the first component (21), wherein the electric motor has a first parasitic capacitance (C parMOTCM1) (22), a second parasitic capacitance (C parMOTCM2 ) (23) and a motor impedance (Z MOT )(25), wherein the first impedance (Z CM ), the second impedance (Z YCK ), the motor impedance (Z MOT )and the second parasitic capacitance (C parMOTCM2 ) are connected together by means of the electrical feedback (27) in such a way that the Wheatstone bridge is realized, wherein the first impedance Z CM , the motor impedance Z MOT and / or the second impedance Z YCK and / or the first parasitic capacitance C parMOTCM2 are chosen such that the formula ((Z CM ) / (Z MOT )) = ((Z YCK ) / (C parMOTCM2 )) is fulfilled in a specific frequency range or in several specific frequency ranges of the electric motor.

Description

State of the art

[0001] Electric motors are well known. Electronically commutated motors, so-called EC motors, are particularly well known.

[0002] In an EC motor, the drive has commutation electronics that supply the EC motor with power. Commutation generates interference signals on the commutation electronics, which, among other things, affect the electric motor. This creates interference signals in the electric motor, such as interference voltages and / or interference currents, which adversely affect the operation of the electric motor.

[0003] Solutions that reduce noise signals are also known, for example, from WO 2022 / 248163 A1. This reduction in noise signals is referred to in expert circles as noise balancing. In this case, the connection between the electronics and the motor is established via the motor phases. However, with this known variant, the required capacitances of the known circuit must be recharged every time the common-mode voltage or common-mode current changes, which leads to increased losses in the inverters. Object and advantages of the invention

[0004] The object of the present invention is to provide an electric motor with an electronic assembly in which the interference signals, such as interference voltages and / or interference currents, are comparatively easily reduced or reduced and the disadvantages known from the aforementioned prior art are reduced.

[0005] This task is solved by the independent claims.

[0006] The dependent claims mention exemplary variants of the invention.

[0007] The invention is based on an electric motor with an electronic assembly, wherein the electric motor has two or more coils, wherein the coils of the electric motor are arranged in a so-called star connection.

[0008] A star connection is the interconnection of any number of components to a common point, known as the star point. For example, the components are designed as at least two coils, and the coils are interconnected at a common point, the star point. For example, an electric motor has three or more coils.

[0009] The essential point of the invention is that the star point of the star connection is designed to be contacted, wherein the electronic assembly has an electrical return, wherein the star point is connected to a phase line by means of the electrical return, so that the motor circuit diagram has the form of a Wheatstone bridge, wherein a first impedance Z CM , a motor impedance Z MOT and / or a second impedance Z YCK and / or a first parasitic capacitance C parMOTCM2 are chosen such that the formula ((Z CM ) / (Z MOT )) = ((Z YCK ) / (C parMOTCM2 )) is met in a specific frequency range or in several specific frequency ranges of the electric motor. This makes it relatively easy to reduce interference signals, such as interference voltages and / or interference currents.

[0010] For example, the motor circuit diagram is the circuit diagram of the electric motor and the electronics assembly. For example, the motor circuit diagram is the electrical (motor) equivalent circuit of the inverter with EMC filter and motor. For example, the equivalent circuit of the electric motor, for example with integrated electronics of the electronics assembly, has the form of a Wheatstone bridge.

[0011] For example, the star point has one or more impedances (Z add ). It is conceivable that the impedance (Z add ) as a capacity (C add ). It is conceivable that the impedance is designed as an electrical feedback (C add ). It is conceivable that the electrical feedback (C add ) or the electrical returns (C add ) connects the star point to a phase line or a neutral conductor. It is also conceivable that one of the electrical returns (C add) is connected to each of the phase lines. This allows for a simple implementation of the Wheatstone bridge circuit.

[0012] For example, the star point is electrically connected to the electrical return or a part of the electrical return. For example, an electrical return connects the star point to a phase in an electrically conductive manner. For example, the star point is connected to a ground, e.g., the stator potential. It is conceivable that the star point is connected to ground via a capacitance, e.g., a capacitor. It is conceivable that the star point connects ground to the electrical return (C add ) connects.

[0013] It is further proposed that the electrical feedback be defined as a capacitance (C add), as a discrete component and / or as an impedance. This makes it relatively easy to reduce the interference signal. It also allows for a comparatively compact and cost-effective electric motor design.

[0014] For example, the electrical return has a capacity (C add ), e.g. a capacitor, a discrete component and / or an impedance.

[0015] According to the invention, two components are provided, wherein one component has an impedance, wherein a first component of the two components has a first impedance (Z CM ), wherein a second component of the two components has a second impedance (Z YCK ), wherein the electrical feedback connects the star point to the first component, wherein the electric motor has a first parasitic capacitance (C parMOTCM1 ), a second parasitic capacitance (C parMOTCM2 ) and a motor impedance (ZMOT ), where the first impedance (Z CM ), the second impedance (Z YCK ), the motor impedance (Z MOT )and the second parasitic capacitance (C parMOTCM2 ) are interconnected via electrical feedback in such a way that a Wheatstone bridge is realized. This allows for a comparatively simple reduction of interference signals.

[0016] For example, the electrical feedback connects the star point to the first impedance (Z CM ) electrically conductive. For example, the electric motor has two components. It is also conceivable that the electric motor has three, four, or more components. For example, the electric motor has two or more components. It is conceivable that the electronic assembly of the electric motor has two or more components.

[0017] It is conceivable that the electrical return is designed as a cable, a wire, or a conductor track. For example, the electrical return has a small or low impedance. For example, the impedance of the electrical return is in relation to the first impedance (Z CM ), to the second impedance (Z YCK ) and motor impedance (Z MOT )small.

[0018] In an exemplary embodiment of the invention, the first component of the electric motor is designed such that the formula ((Z CM ) / (Z MOT )) = ((Z YCK ) / (C parMOTCM2 )) is satisfied. This achieves ideal bridge balancing and thus the ideal state of the electric motor. It is conceivable that the first component is selected such that the formula is satisfied in a specific frequency range or in several specific frequency ranges of the electric motor.

[0019] In reality, the formula (ZCM ) due to component and assembly tolerances, it is therefore suggested that the impedances, for example the first component, be chosen such that the formula is approximately satisfied. For example, the impedance (Z CM ) , (Z MOT )and / or (Z YCK ) and / or the capacity (C parMOTCM2 ) is chosen such that the ratio (Z CM ) / (Z MOT )and (Z YCK ) / (C parMoTcM2 ) results in a small functional disturbance voltage. In the ideal state - in the limit state - the formula ((Z CM ) / (Z MOT )) = ((Z YCK ) / (C parMOTCM2 )) fulfilled.

[0020] It is also conceivable that the values ​​given in the formula (Z CM ) can be selected such that the formula is satisfied or approximately satisfied in a specific frequency range of the electric motor. This allows the electric motor to be adapted to a specific application.

[0021] It is also proposed that the electric motor be designed as a three-strand or three-phase electric motor. However, it is also conceivable that the electric motor be a single-phase electric motor or a direct current electric motor. For example, the electric motor is designed as an electronically commutated electric motor (EC motor). For example, the electric motor has two, three, or more coils with an inductance. For example, each coil of an electric motor with three coils has a winding inductance (L u , L v or L w ) on.

[0022] A design of the electric motor as proposed is suitable, for example, for electronically commutated electric motors.

[0023] For example, the electronics assembly includes the components required for commutation of the electric motor. In particular, the electronics assembly includes all the components required for commutation of the electric motor. It is conceivable that the electronics assembly is arranged integrally with the electric motor. However, it is also conceivable that the electric motor and the electronics assembly are spatially separated from each other. For example, the electronics assembly includes the electrical feedback.

[0024] It is also proposed that the first component be designed as a filter choke. For example, the first component has a plurality of filter chokes, wherein the plurality of filter chokes together form the first impedance (Z CM ). This creates the first impedance (Z CM ) comparatively easy in the direction of fulfilling the formula ((Z CM ) / (Z MOT )) = ((Z YCK ) / (C parMOTCM2)), especially with regard to different frequencies of the electric motor, through which the values ​​of the first impedance (Z CM ), the second impedance (Z YCK ), the motor impedance (Z MOT )and the second parasitic capacitance (C parMOTCM2 ) can change.

[0025] It is also proposed that the first component consist of a discrete and / or passive element. However, it is also conceivable that the first component comprises a clocked semiconductor or is present as an assembly of elements. It is conceivable that the first component is designed to match the desired frequency range of the electric motor. The first component is designed, for example, as a passive power factor correction filter (PFC), as an active power factor correction filter (PFC), as an inverse converter (buck-boost converter), or as a switched-mode power supply.

[0026] It is also proposed that the electrical feedback be connected to the star point via two or more capacitors. For example, one capacitor electrode of each of the two or more capacitors is connected to the star point.

[0027] For example, two or more of the capacitors form the capacitance (C add ) of the electrical feedback. It is also conceivable that the capacitors have the capacitance (C add ) of the electrical return. For example, the electrical return includes the capacitors via which the cable or electrical line of the electrical return is connected to the star point. For example, the electrical return comprises several cables or several electrical lines. It is conceivable that each cable is connected to the star point via a capacitor.

[0028] For example, the capacitors are connected to each other via a virtual star point, and the electrical feedback is electrically connected to the capacitors at the virtual star point. It is conceivable that one capacitor electrode of each capacitor is electrically connected to the virtual star point. It is conceivable that the electric motor has at least two capacitors in a single-phase or DC version. It is also conceivable that the electric motor has at least three capacitors in a two-phase version.

[0029] For example, the electrical return is designed as a parasitic capacitance.

[0030] It is further proposed that the electrical feedback be defined as a capacitance (C add ) is present and the capacity (C add) is selected depending on the design of the electric motor and / or its application. This allows the electric motor to be adapted to its design or its specific application. It is conceivable that the electrical feedback is selected depending on the application of the electric motor and thus depending on the design of the electric motor.

[0031] An exemplary embodiment of the invention is a method for reducing interference signals of an electric motor according to one of the previously mentioned variants, wherein the method is characterized by the following method steps: - Selection of the first impedance (Z CM ) and the second impedance (Z YCK ), so that the formula ((Z CM ) / (Z MOT )) = ((Z YCK ) / (C parMOTCM2 )) is fulfilled, - Selection of capacity (C add) depending on the design of the electric motor and / or depending on the application of the electric motor, - Arranging the first impedance (Z CM ), the second impedance (Z YCK ) and the capacity (C add ) to the electric motor.

[0032] It is also conceivable that the method has iteration loops, so that first the first impedance (Z CM ), the second impedance (Z YCK ) and the capacity (C add ) and placed on the electric motor. The interference signal is then determined and, depending on this, the first impedance (Z CM ), the second impedance (Z YCK ) and / or the capacity (C add ) is changed. For example, the iteration loop is repeated until the equation ((Z CM ) / (Z MOT )) = ((Z YCK ) / (C parMOTCM2)) is met or approximately met at least for the desired frequency range or ranges of the electric motor. Character description

[0033] Several embodiments are explained in more detail with reference to the following drawings, giving further details and advantages: They show: Fig. 1 a schematic representation of an electric motor with an electronic assembly, Fig. 2 an equivalent circuit diagram of a known three-phase, star-connected electric motor, Fig. 3 the equivalent circuit diagram according to Fig. 2 converted into an equivalent circuit which is valid for common mode quantities, Fig. 4 an equivalent circuit diagram of an electric motor with electronics with a common mode choke and Fig. 5 the equivalent circuit diagram according to Fig. 4, where the equivalent circuit is expanded by a capacitance (Cadd ), whereby the equivalent circuit has the form of a Wheatstone bridge.

[0034] In Fig. Figure 1 shows a schematic representation of an electric motor 32, which has an electronic assembly 33. The electric motor further includes a first coil 34 and a second coil 35. The first and second coils 34, 35 are electrically connected to each other at a star point 36.

[0035] Fig. Figure 2 shows an equivalent circuit diagram 1 of a known three-phase electric motor. The electric motor has three coils 2, 3, 4, each of which has a winding inductance (L y , L y , L w). The three coils of the electric motor 2, 3, 4 are electrically connected to one another at a star point 5. Each of the three coils 2, 3, 4 is connected at one end 6, 7, 8 to a phase line U, V, W, and at the other end 13, the coils 2, 3, 4 are connected via the star point 5 to a ground or the protective conductor. Furthermore, the known electric motor has a first parasitic capacitance 12 (C parMOTCM1 ) and second parasitic capacitances 9, 10, 11 (1 / 3 C parMOTCM2 ) on.

[0036] In Fig. 3 is the equivalent circuit according to Fig. 2 into an equivalent circuit diagram 14 valid for common mode (CM) quantities. In the equivalent circuit diagram 14, the winding inductances (L v , L y , L w ) to an inductance 15 (LMOTCM), as well as the second parasitic capacitances 9, 10, 11 (1 / 3 C parMOTCM2 ) to a parasitic capacitance 16 (C parMOTCM2) are combined or transferred. At point 17, the coils of the electric motor are connected to the phases (U, V, W) of the three-phase current.

[0037] In Fig. Figure 4 shows the common-mode equivalent circuit 18 of an EC motor. The common-mode equivalent circuit 18 shows a common-mode interference voltage 19 (U CMWR ), which results from the use of an inverter, which is provided for the operation of the electric motor. Furthermore, the total capacitance of all capacitors in the DC link is 20 (C YZK ). For example, all capacitors and / or parasitic capacitances present in the DC link are connected to ground. In addition, a common-mode impedance 21 (Z CM), which is formed by one or more filter chokes of the electric motor. The filter choke is used to suppress or reduce the negative influence of the common-mode interference voltage 19 at a point 26. The filter choke has the properties relevant for the common-mode interference voltage: resistance EPR CM , Capacity EPC CM and inductance L CM Also shown are the first parasitic capacitance 22 (C parMOTCM1 ) and the second parasitic capacitances 23 (C parMOTCM2 ) of the electric motor. The star point at which the two or more coils of the electric motor are connected is shown at point 24. Furthermore, the impedance 25 of the motor (Z MOT ) is shown. The impedance 25 of the motor has the properties relevant for the common mode interference voltage 19 resistance EPR LMOTCM , Capacity EPC LMOTCM and inductance L LMOTCM The common-mode interference voltage 19 (U CMWR) can be measured indirectly at point 26. The measuring instrument has an impedance 31 (Z LISN ). For example, the capacity is 20 (C YZK ) and common mode impedance 21 (Z CM ) Component of the electronic assembly.

[0038] To avoid a negative influence of the common mode interference voltage 19 (U CMWR ) comparatively easily, the invention proposes to connect the star point 24 by means of an electrical return 27 to the phase line 30 or a neutral conductor at point 28. In Fig. In Figure 4, the electrical feedback 27 is shown in dashed lines to illustrate the difference between the known prior art and the circuit modification according to the invention.

[0039] For example, the electrical return 27 has an additional capacity 29 (C add ) on.

[0040] In Fig. Figure 5 shows the circuit with the electrical feedback 27 in the form of a Wheatstone bridge. In conventional Wheatstone bridges, the common-mode interference voltage 19 is tapped. According to the invention, however, the object is to minimize the influence of the common-mode interference voltage 19. For this purpose, the interference voltage 30 (U Stör ), which is influenced by the common mode interference voltage 19, is measured on the phase line against a ground by the measuring instrument at point 26.

[0041] Through the circuit design according to Fig. 5 it is now possible, by appropriate choice of parameters capacity 20 (C YZK ), common mode impedance 21 (Z CM ) and / or electrical feedback 27 or additional capacity 29 (C add ) to reduce the common-mode interference voltage 19 towards zero. In particular, this makes it possible to reduce the interference voltage 30 (U Stör) for an operating frequency or for an operating frequency range of the electric motor towards zero or to zero. This reduces the influence of the common-mode interference voltage 19. List of reference symbols 1 equivalent circuit diagram 2 coils 3 coil 4 coil 5 star point 6 End 7 End 8 End 9 parasitic capacitance 10 parasitic capacitance 11 parasitic capacitance 12 parasitic capacitance 13 End 14 Equivalent circuit diagram 15 Inductance 16 capacity 17 points 18 Common-mode equivalent circuit 19 Common mode interference voltage 20 capacity 21 Common mode impedance 22 capacity 23 capacity 24 point 25 Impedance 26 positions 27 Repatriation 28 points 29 capacity 30 interference voltage 31 Impedance 32 electric motor 33 Electronic assembly 34 coil 35 coil 36 star point

Claims

[1] Electric motor (32) with an electronic assembly (33), wherein the electric motor (32) has two or more coils (2 - 4), wherein the coils (2 - 4) of the electric motor (32) are arranged in a so-called star connection, wherein the star point (13, 24, 36) of the star connection is designed to be contacted, wherein the electronic assembly (33) has an electrical return (27), wherein the star point (13, 24, 36) is connected to a phase line by means of the electrical return (27), so that the motor circuit diagram has the form of a Wheatstone bridge, wherein two components are present, wherein a first component (21) has a first impedance (Z CM ), wherein a second component (20) has a second impedance (Z YCK ), wherein the electrical return (27) connects the star point (13, 24) to the first component (21), wherein the electric motor has a first parasitic capacitance (C parMOTCM1) (22), a second parasitic capacitance (C parMOTCM2 ) (23) and a motor impedance (Z MOT )(25), wherein the first impedance (Z CM ), the second impedance (Z YCK ), the motor impedance (Z MOT )and the second parasitic capacitance (C parMOTCM2 ) are connected together by means of the electrical feedback (27) in such a way that the Wheatstone bridge is realized, wherein the first impedance Z CM , the motor impedance Z MOT and / or the second impedance Z YCK and / or the first parasitic capacitance C parMOTCM2 are chosen such that the formula ((Z CM ) / (Z MOT )) = ((Z YCK ) / (C parMOTCM2 )) is fulfilled in a specific frequency range or in several specific frequency ranges of the electric motor. [2] Electric motor (32) according to one of the preceding claims, characterized by that the electrical return (27) acts as a capacitance (C add) (29), as a discrete component or as an impedance. [3] Electric motor (32) according to one of the preceding claims, characterized by that the electric motor (32) is designed as a three-strand electric motor. [4] Electric motor (32) according to one of the preceding claims, characterized by that the first component (21) is designed as a filter choke. [5] Electric motor (32) according to one of the preceding claims, characterized by that the first component (21) consists of discrete and / or passive elements [6] Electric motor (32) according to one of the preceding claims, characterized by that the electrical return (27) is connected to the star point (13, 24) via two or more capacitors. [7] Electric motor (32) according to one of the preceding claims, characterized by that the electrical return (27) acts as a capacitance (C add ) is present and the capacity (C add) is selected depending on the design of the electric motor and / or the application of the electric motor. [8] Method for reducing interference signals of an electric motor (32) according to one of the preceding claims, characterized by the following method steps: - Selection of the first impedance (Z CM ) and the second impedance (Z YCK ), so that the formula ((Z CM ) / (Z MOT )) = ((Z YCK ) / (C parMOTCM2 )) is fulfilled, - Arranging the first impedance (Z CM ) and the second impedance (Z YCK ) to the electric motor.

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