PCB-based twisted torsional excitation winding in rotary transformer

Abstract

Embodiments of the present disclosure provide a resolver (RT) including a printed circuit board (PCB) and a set of secondary windings integrated with the PCB. The set of secondary windings includes a plurality of traces extending over a first region of the PCB and a second region of the PCB. A plurality of traces are organized in a first region of the PCB in a first position order. The plurality of traces are organized in a second region of the PCB in a second position order.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of the prior filing date of U.S. Provisional Application Serial No. 63 / 333,790, filed on April 22, 2022, the entire disclosure of which is incorporated herein by reference. Background Art

[0003] A wound-rotor synchronous machine (WRSM) is an electric motor with a rotor and a stator. The stator is the fixed part of the machine, while the rotor is the rotating part of the machine. The stator usually has a multi-phase winding, while the rotor is made with a field winding that replaces the permanent magnets. The rotor rotates in a magnetic field, and the magnetic field can be generated by the windings or field coils. The field coil is an electromagnet that is used to generate a magnetic field in an electromagnetic machine, which is typically a rotating electrical machine such as a motor or a generator. It consists of a coil of wire through which an electric current flows. In the case of a machine with a field coil, an electric current must flow in the coil to generate a magnetic field, otherwise no power is transferred to or from the rotor. The process of generating a magnetic field with the help of an electric current is called excitation. The field coil produces the most flexible form of flux regulation and de-regulation, but at the expense of the flow of electric current.

[0004] Conventionally, the rotor windings of a WRSM can be powered or excited using a slip ring and brush assembly system. However, the slip ring and brush assembly system has disadvantages, including low efficiency at high speeds, frequent maintenance requirements, and overall loss, especially at high speeds due to the high contact resistance between the brushes and the slip rings.

[0005] In order to avoid the shortcomings of the slip ring and brush assembly excitation methods, wireless (or contactless) excitation or wireless power transfer systems have been developed. In general, wireless power transfer uses various technologies to transfer energy by means of an electromagnetic field (EMF) without the need for a physical link. In a wireless power transfer system, a transmitter device driven by electric power from a power source generates a time-varying EMF, which transmits power to a receiver device via mutual inductance (M) across space. The receiver device extracts power from the EMF using M and supplies the extracted power to an electrical load. Wireless power transfer provides power to electrical devices where interconnecting wires is inconvenient, dangerous or impossible. Wireless power technology is mainly divided into two categories, near field and far field. In near field technology, time-varying EMF is generated using various technologies, including resonant inductive coupling. Resonant inductive coupling is a near-field wireless transfer of electrical energy between magnetically coupled coils, which are part of a resonant circuit that is tuned to resonate at the same frequency as the drive frequency.

[0006] A rotary transformer (RT) is a wireless power transfer system that can be used for controlled wireless excitation of the rotor winding of a WRSM. RT performs the same general function as a conventional transformer, i.e., both transfer electrical energy from one circuit to another at the same frequency but different voltages. Conventional transformers work on the principle of electromagnetic induction, i.e., an electromotive force is induced in a closed circuit due to a variable magnetic field around it. The difference between RT and conventional transformers is that the RT geometry is arranged so that the primary winding and the secondary winding can rotate relative to each other, and the change in electrical characteristics is negligible. In a known configuration, the RT can be constructed by winding the primary winding and the secondary winding into separate halves of a cup-shaped core. The concentric halves face each other, with each half mounted on one of the parts that rotate relative to each other. The magnetic flux provides coupling from one half of the cup-shaped core across the air gap to the other half, providing an "M" that transfers energy from the primary winding of the RT to its secondary winding.

[0007] Known methods of using RT systems to provide excitation to WRSMs may include a resonant tuning network, also known as a compensation network. A resonant tuning network may include circuit components (e.g., various combinations of resistors, inductors, and / or capacitors) that enable an associated transformer to store oscillating electrical energy similar to a resonant circuit, and thus act as a bandpass filter, allowing frequencies close to their resonant frequency to pass from the primary winding to the secondary winding, but blocking other frequencies. The amount of M between the primary and secondary windings, along with the quality factor (Q factor) of the circuit, determines the shape of the frequency response curve. Resonant circuits are often called LC or LRC circuits due to the inductance (L), resistance (R), and capacitance (C) components used to form the resonant circuit. In materials science, each material has its own natural frequency. If the external vibration is equal to the natural frequency, resonance occurs. In electrical science, the impedance of an inductor and a capacitor depends on the frequency. The impedance of a capacitor is inversely proportional to the frequency, while the impedance of an inductor is directly proportional to the frequency. At a specific frequency, the two cancel each other out. Such a circuit is called a resonant circuit, and the specific frequency is the resonant frequency.

[0008] In conventional RT systems, a resonant tuning network (or compensation network) is provided on each of the stationary (or stator, or primary) side and the rotating (or rotational, or secondary) side of the WRSM. For the primary coil, the basic function of "compensation" is to minimize the input apparent power and / or minimize the voltage-ampere (VA) rating of the power supply. For the secondary coil, compensation cancels out the leakage inductance of the secondary coil in order to maximize the transfer capacity.

[0009] Generally, electric motors can be relatively complex structures with parts that rotate at high speeds and generate high temperatures. In addition, the use of various forms of electromotive force, EMF, complex communication signals, high frequency (HF) communication signals, complex motor control operations, and the like can add further complexity. Moreover, for many applications, the size and weight of the motor must be controlled. Therefore, it would be valuable to provide a motor design that prioritizes compact size; reduced cost; simplification of electrical, mechanical, and thermal design; reduced eddy current losses; and an improved method for providing a PCB-based winding that can effectively and efficiently handle HF communication signals. Summary of the invention

[0010] An embodiment of the present disclosure provides a rotary transformer (RT) comprising a printed circuit board (PCB) and a set of secondary windings integrated with the PCB. The set of secondary windings comprises a plurality of traces extending on a first region of the PCB and a second region of the PCB. The plurality of traces are organized in a first position sequence in the first region of the PCB. The plurality of traces are organized in a second position sequence in the second region of the PCB.

[0011] Embodiments of the present disclosure provide a method for forming an RT, the RT comprising a printed circuit board (PCB) and a set of secondary windings integrated with the PCB. The set of secondary windings comprises a plurality of traces extending on a first region of the PCB and a second region of the PCB. The plurality of traces are organized in a first position sequence in the first region of the PCB. The plurality of traces are organized in a second position sequence in the second region of the PCB. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a simplified block diagram illustrating a non-limiting example of an electric drive motor system with integrated power electronics according to aspects of the present disclosure;

[0013] Figure 2 is a simplified block diagram showing a three-dimensional (3D) view and a front-side view of a non-limiting example of how a portion of a rotating side of an electric machine may be configured to include integrated power electronics according to aspects of the present disclosure;

[0014] Figure 3 depicts equations according to aspects of the present disclosure;

[0015] Figure 4 is a simplified block diagram illustrating a non-limiting example of a portion of a RT according to aspects of the present disclosure;

[0016] Figure 5 depicts an optimization equation according to aspects of the present disclosure;

[0017] Fig. 6Adepicts a simplified block diagram showing multiple traces according to aspects of the present disclosure;

[0018] Figure 6B depicts a simplified block diagram showing multiple traces according to aspects of the present disclosure;

[0019] Figure 6C depicts a simplified block diagram showing multiple traces according to aspects of the present disclosure;

[0020] Fig. 7A A PCB with twist-free turns is depicted;

[0021] Figure 7B depicts a PCB with twisted strands according to aspects of the present disclosure;

[0022] Fig. 8A depicts a simplified block diagram illustrating a full twist according to aspects of the present disclosure;

[0023] Figure 8B depicts a simplified block diagram illustrating partial twisting according to aspects of the present disclosure;

[0024] Fig. 9 depicts a PCB with twisted strands according to aspects of the present disclosure;

[0025] Fig.10 is a simplified block diagram illustrating a non-limiting example of how layer-to-layer twisting may be implemented using a via structure in accordance with aspects of the present disclosure; and

[0026] Fig.11 is a simplified block diagram illustrating a computer system operable to implement embodiments of the present disclosure. DETAILED DESCRIPTION

[0027] Embodiments of the present disclosure provide a novel integrated power electronics system that can be used in an electric motor drive system having a wireless power transfer (or RT) network. The electric motor drive system may include an electric motor (e.g., a WRSM) having a fixed side and a rotating side. In embodiments of the present disclosure, the integrated power electronics system may be implemented as an integrated mounting and / or communication structure, and selected portions of the motor and / or wireless power transfer system may be integrated with the structure to provide improved physical support, improved electronic communication, and improved cooling. On the rotating side, instances of the integrated mounting and / or communication structure may be used to integrate secondary windings; rotating side elements of the RT (if any); rectifiers; and various electronic connections between the secondary windings, the rotating side elements of the RT, and the rectifiers. On the fixed side, instances of the integrated mounting and / or communication structure may be used to integrate inverters; fixed side elements of the RT; primary windings; and various electronic connections between the inverter, the fixed side elements of the RT, and the primary windings.

[0028] In some embodiments of the present disclosure, the integrated mounting and / or communication structure may be implemented as a multi-layer printed circuit board (PCB) operable to combine primary windings, secondary windings, transistors (e.g., for inverters), diodes (e.g., for rectifiers), wiring, and the like within its layers. On the rotating side where cooling is required, the PCB may include an assembly area operable to accommodate certain components (e.g., diodes for rectifiers) and cooling mechanisms for the accommodated components.

[0029] The PCB-based secondary winding has similarities to other PCB-based fixed planar inductor or transformer designs. However, compared with the fixed planar transformer, the RT's PCB-based secondary winding has two different features. Specifically, the primary core must have a considerable gap to accommodate the secondary PCB structure; and the primary and secondary windings are physically separated, which means that the conventionally used interleaving between the primary and secondary windings is not feasible for RT PCB-based applications. Therefore, the traditional design of multi-strand PCB-based windings results in significantly high losses in RT applications. In an embodiment of the present disclosure, an optimized multi-strand PCB-based winding design and optimization method are proposed to minimize losses and temperature rise.

[0030] Therefore, the integrated mounting and / or communication structure (e.g., PCB) and / or optimized multi-strand PCB-based winding design and optimization method described herein provide technical advantages and technical effects. The secondary winding and rectifier subsystem are assembled in the same PCB structure, which significantly simplifies the design, prototype development and production of the associated RT. The embodiments of the present disclosure also reduce or eliminate the termination and interconnection difficulties between the rectifier and secondary winding assemblies. The embodiments of the present disclosure also allow the assembly area (e.g., the assembly area of ​​the diodes accommodating the rectifier) ​​to be directly mounted on the motor shaft using, for example, an aluminum support sleeve, which provides high mechanical robustness and simpler thermal management. Therefore, according to aspects of the present disclosure, the integrated mounting and communication structure implements a motor design that prioritizes compact size; reduced cost; simplification of electrical, mechanical and thermal design; reduced eddy current losses; and the ability to efficiently and effectively handle HF communication signals.

[0031] Turning now to a more detailed description of embodiments of the present disclosure, Figure 1A system 100 embodying aspects of the present disclosure is depicted. The system 100 includes an energy source 110 electronically coupled to an electric motor drive system 102. The electric motor drive system 102 includes an inverter / RT system 120, a DC-excited motor 140, and a controller 170, configured and arranged as shown. According to aspects of the present disclosure, the inverter / RT system 120 includes an integrated mounting and communication structure 160, which is operable to integrate with the inverter system 122; an RT system 124; an electrical connector 128, which is operable to electrically couple the inverter system 122 to the RT system 124; a primary winding 126; and an electrical connector 130, which is operable to electrically couple the RT system 124 to the primary winding 126. According to aspects of the present disclosure, the DC-excited motor 140 includes an integrated mounting and communication structure 162 operable to be integrated with the secondary winding 146; a rectifier system 142; and an electrical connector 150 operable to electrically couple the secondary winding 146 to the rectifier system 142. Although the inverter / RT system 120, the DC-excited motor 140, and the controller 170 are depicted as separate components, it should be understood that the inverter / RT system 120, the DC-excited motor 140, and the controller 170 can be configured and arranged in any suitable combination. For example, the controller 170 can be incorporated within the inverter / RT system 120; the inverter / RT system 120 can be incorporated within the DC-excited motor 140; and / or the inverter / RT system 120 and the controller 170 can be incorporated within the DC-excited motor 140. In addition, the system 100 includes a stationary side (e.g., a stator side) 220 and a rotating side (e.g., a rotor side) 230. Generally speaking, the stationary side 220 includes the primary winding 126 and circuit elements to the left thereof, while the rotating side 230 includes the secondary winding 146 and circuit elements to the right thereof.

[0032] The energy source 110 can be implemented in various forms, including, for example, as a battery. In some embodiments of the present disclosure, the battery can be a battery pack having a group of one or more individual battery cells connected in series or in parallel and operating under the control of one or more controllers, such as a battery control module (BCM) that monitors and controls the performance of the battery pack. For example, the BCM can monitor several battery pack level characteristics, such as the battery pack current, battery pack voltage, and battery pack temperature measured by a current sensor. The battery pack can be recharged by an external power source (not shown). The battery pack can include power conversion electronics that are operable to regulate power from an external power source to provide the battery pack with appropriate voltage and current levels. The individual battery cells within the battery pack can be composed of various chemical formulas. The battery pack chemical composition can include, but is not limited to, lead acid, nickel cadmium (NiCd), nickel metal hydride (NIMH), lithium ion, or lithium ion polymer.

[0033] The inverter 122 may be a resonant inverter 122 electrically coupled between the energy source 110 and the DC-excited motor 140 to transfer excitation energy from the energy source 110 to the DC-excited motor 140 through the RT system 124 and the primary winding 126. More specifically, the resonant inverter 122 is operable to provide energy from the energy source 110 to the RT system 124 at a desired resonant frequency for the purpose of providing excitation to the DC-excited motor 140 through the primary winding 126. In an embodiment of the present disclosure, the resonant inverter 122 is operable to convert a DC voltage from the energy source 110 to an AC current of a desired resonant frequency in accordance with the requirements of the AC-excited motor 140 and the RT system 124 for motor excitation. In an embodiment of the present disclosure, the resonant inverter 122 may be a full-bridge resonant inverter having four switches organized into two "phase legs". Each phase leg may include two switches connected in series and connected between a positive DC rail and a negative DC rail. The phase node may be positioned between the two switches of each phase leg to provide the phase of the AC waveform output at the desired resonant frequency. In some embodiments of the present disclosure, the resonant inverter 122 generates HF AC. The controller 170 is electrically coupled to the phase leg switches to control the on / off state of the switches, thereby controlling the frequency and phase of the AC waveform generated by the resonant inverter 122. The controller 170 includes a computing device including a computer or microprocessor configured and operable to execute software commands and programs, and may include associated firmware such that the controller is configured and operable to control the on / off switching operation of the resonant inverter 122. In embodiments of the present disclosure, the controller 170 may be configured and arranged to include a computing system 1100 ( Fig.11 The controller 170 is also configured to send various control commands to the DC-excited motor 140 to control, for example, the torque and / or speed of the motor 140.

[0034] The DC-excited motor 140 can be any compromise motor design suitable for the work to be performed by the motor. In conventional automotive-based motor applications, examples of work that can be done by the motor include operating or moving power windows; power seats; fans for heaters and radiators; windshield wipers; and / or the engine of a vehicle with a hybrid electric vehicle configuration. Regardless of the type of DC-excited motor 140, it relies on electromagnetic and flipping magnetic fields to generate mechanical power. Conventional implementations of DC-excited motors 140 include five basic parts, namely a stator; a rotor; a solid shaft; a coil; and a so-called "squirrel cage." The windings of the stator in a DC-excited motor are rings of electromagnets that are paired in sequence and energized, which produces a rotating magnetic field. The rotor in a DC-excited motor does not have any direct connection to the power supply, and it has no brushes. Instead, it often uses the squirrel cage described previously. The squirrel cage in a DC-excited motor is a set of rotor bars connected to two rings, one at each end. The squirrel cage rotor goes inside the stator. When the excitation power is sent through the stator, it generates an EMF. The bars in the squirrel cage rotor are conductors, so they react to the flipping of the stator's magnetic poles, which causes the rotor to spin and creates its own magnetic field. The key to an induction motor (where the rotor's magnetic field is induced by the stator's magnetic field) is that the rotor is always trying to catch up. It's always looking for static equilibrium, so it's spinning to find that stable state. However, the EMF generated by the stator is always a little faster than the rotor's magnetic field. The rotation of the rotor creates torque, which is needed to create mechanical power to turn the wheels of a car or the blades of a fan. Some DC-excited motors use a wound rotor (such as a WRSM), which is wrapped with wire instead of a squirrel cage. In either case, there is only one moving part in a DC-excited motor, which means there are fewer things to replace or maintain.

[0035] As noted, in some embodiments of the present disclosure, the DC-excited motor 140 may be a WRSM. A WRSM is a rotary electric motor having a rotor and a stator. The stator is the stationary portion of the machine, while the rotor is the rotating portion of the machine. The stator typically has a multi-phase winding, while the rotor is made with a field winding that replaces the permanent magnets. The rotor rotates in a magnetic field, and the magnetic field may be generated by windings or field coils. In the case of a machine with a field coil, an excitation current must flow in the coil to generate a magnetic field, otherwise no power is transferred to or from the rotor. The field coil produces the most flexible form of flux regulation and deregulation, but at the expense of the flow of current. Conventionally, the rotor windings of a WRSM may be powered or excited with a slip ring and brush assembly. However, slip ring and brush systems have disadvantages, including low efficiency at high speeds, frequent maintenance requirements, and overall losses, particularly at high speeds, due to high contact resistance between the brush and slip ring system.

[0036] To avoid the disadvantages of the slip ring and brush assembly excitation method, the RT compensation system 124, the primary winding 126, and the secondary winding 146 are operable to provide wireless excitation or wireless power transfer from the fixed side 220 to the rotating side 230. The secondary winding 146 is close enough to the primary winding 126 to be within the EMF generated by the primary winding 126 so that M is between the primary winding 126 and the secondary winding 146. The secondary winding uses M to generate an AC charging signal, and the rectifier system 142 converts the AC charging signal to a DC charging signal, which is provided to the rotor (now shown as being separated from the motor 140). In some embodiments of the present disclosure, the RT compensation system 124 can be implemented as a specially designed fixed side only RT compensation system 124. In general, RT is a circuit and method for wireless power transfer to the secondary winding of the WRSM for controlled excitation. RT is essentially the same as a conventional transformer in that it transfers electrical energy from one circuit to another at the same frequency but at different voltages. In general, conventional transformers work on the principle of electromagnetic induction, i.e., an electromotive force is induced in a closed circuit due to a variable magnetic field around it. The difference between an RT and a conventional transformer is that the geometry of the RT is arranged so that the primary and secondary windings can rotate relative to each other with negligible changes in the electrical characteristics. In a known configuration, the RT can be constructed by winding the primary and secondary windings into separate halves of a cup-shaped core. The concentric halves face each other, with each half mounted on one of the parts that rotate relative to each other. The magnetic flux provides coupling from one half of the cup-shaped core across the air gap to the other half, providing an "M" that couples energy from the primary winding of the RT to its secondary winding.

[0037] In conventional RT designs, a resonant tuning network (or compensation network) is provided on each of the stationary (or primary) side and the rotating (or secondary) side of the WRSM. RT designs having resonant circuit components on both the stationary and rotating sides of the WRSM are difficult to implement. For example, it is difficult in practice to place a resonant tuning network or compensation circuit on the secondary side due to very limited rotor space and high temperature rotor operating conditions that exceed the temperature ratings of commercially available compact capacitors. In addition, having a resonant tuning capacitor on the secondary side increases the complexity of the rotating parts, increases mechanical mass, increases inertia, and reduces mechanical reliability, especially at high rotational speeds.

[0038] The fixed-side-only implementation of the RT compensation system 124 solves the difficulties associated with practically implementing (i.e., building and using) conventional RT designs that include a double-sided compensation network by providing the benefits of wireless power transfer without the difficulties associated with providing compensation circuitry on the rotating side of a DC-excited motor 140 (e.g., a WFSM). More specifically, the fixed-side-only implementation of the RT compensation system 124 is operable to wirelessly deliver rotor excitation current from the primary winding 126 to the secondary winding 146, thereby eliminating brush and slip ring maintenance issues, as well as the inefficiencies, manufacturing challenges, and design drawbacks associated with brush and slip ring systems.

[0039] In aspects of the present disclosure, a fixed side-only implementation of the RT compensation system 124 takes into account the absence of a resonant tuning capacitor on the secondary side by providing an additional resonant tuning capacitor on the primary side (i.e., one of the resonant tuning capacitors of the fixed side-only resonant LCC) and adjusting the two primary side resonant tuning capacitors so that the uncompensated secondary side does not impose inefficiencies or other disadvantages on the RT compensation system 124. In an embodiment of the present disclosure, a fixed side-only LCC design method is provided, which includes reflecting the impedance and / or inductance of the secondary side to the primary side, and the leakage inductance of the secondary winding 146 is tuned on the primary side. In general, the reflected impedance (or inductance) is a portion of the impedance in a circuit (e.g., circuit A) caused by affecting another coupled circuit (e.g., circuit B). In an embodiment of the present disclosure, this can be achieved by deriving an equivalent circuit model of the system 100 and an overall impedance model of the system 100, which allows the calculation of the reflected impedance from the secondary to the primary. Further simplifications are applied to the derived equivalent circuit model so that the total impedance seen by the resonant inverter 122 can be calculated. To tune this total impedance to unity power factor, the tuning capacitors of the LCC design are recalculated. Thus, the fixed side-only implementation of the RT compensation system 124 eliminates the need for capacitor tuning on the secondary side, as well as the need for one or more secondary side resonant tuning capacitors and their tuning, by providing additional primary side tuning components (e.g., one or more resonant tuning capacitors) and adjusting the values ​​of the tuning components on the primary side.

[0040] Figures 2 to 10 Examples of how various embodiments of the present disclosure can be designed and manufactured according to aspects of the present disclosure are depicted. For the sake of brevity, conventional techniques related to manufacturing and using aspects of the present disclosure may or may not be described in detail herein. In particular, various aspects of manufacturing PCBs, electrical components, electronic connections, bonding techniques, and the like that can be used to implement the various technical features described herein are well known. Therefore, for the sake of brevity, many conventional implementation details are only briefly mentioned or omitted entirely herein, without providing well-known system and / or process details.

[0041] In addition, although Figure 2 Focus on Figure 1 The example embodiment of the integrated mounting and communication structure 162, secondary winding 146, electrical connector 150 and rectifier system 142 shown in FIG. 1 , but substantially the same structural options and manufacturing options apply to Figure 1 The integrated mounting and communication structure 160 , inverter system 122 , electrical connector 128 , RT compensation system 124 , electrical connector 130 , and primary winding 126 are shown.

[0042] Figure 2 Depicted are integrated mounting and communication structures 162, secondary winding 146, electrical connector 150, and rectifier system 142 (all in Figure 1 ) may be implemented as additional details of the integrated winding / rectifier 200. Figure 2 A 3D view and a front-side view of a winding / rectifier 200 are depicted, which includes a PCB mounted / communication element 210, a PCB based secondary coil 212, a configuration of diodes 222 arranged as a rectifier circuit, a rectifier assembly 220, and a rotor shaft 224, configured and arranged as shown. Generally speaking, the rotor shaft is the central component of the electric motor. The rotor shaft is the carrier shaft of the rotor's laminated core and is therefore connected to the rotor shaft via a controller 170 ( Figure 1 146 ); and the diode 222 is configured to form a rectifier circuit, which is an example embodiment of the rectifier system 142. The PCB mounting / communication element 210 is a multi-layer PCB structure that is operable to incorporate a PCB-based secondary coil 212 (with or without a magnetic core) formed as a trace in one or more of its layers, together with some or all of the electrical connectors 150 ( Figure 1 ). In some embodiments of the present disclosure, the rectifier diode 222 can be incorporated into one or more layers of the PCB mounting / communication element 210. In some embodiments of the present disclosure, the rectifier diode 222 is mounted within a rectifier assembly 220, which is mounted (e.g., by welding or another suitable bonding mechanism) to an exposed surface of the PCB mounting / communication element 210. According to aspects of the present disclosure, the PCB mounting / communication element 210 and the rectifier assembly 220 are physically bonded to each other so that they function as an integrated structure that houses a portion of the PCB-based secondary coil 212, the rectifier diode 222, and the electrical connector 150. In some embodiments of the present disclosure, the rectifier assembly 222 can be configured to include suitable thermal management elements that are operable to dissipate heat generated by the electric motor 140 ( Figure 1) during operation of the rotating side 230.

[0043] In an alternative configuration of the winding / rectifier structure 200, the PCB mounting / communication element 210 can be configured and arranged so that it is physically mounted (e.g., by welding or another suitable bonding mechanism) to an exposed outer surface of the rectifier assembly 220; and the rectifier assembly 220 is physically mounted (e.g., by welding or another suitable bonding mechanism) to an exposed outer surface of the rotor shaft 224. In another alternative configuration of the winding / rectifier structure 200, the PCB mounting / communication element 210 can be configured and arranged so that it can be physically mounted (e.g., by welding or another suitable bonding mechanism) to an exposed outer surface of the rotor shaft 224; and the rectifier assembly 220 is also physically mounted (e.g., by welding or another suitable bonding mechanism) to an exposed outer surface of the rotor shaft 224. In some embodiments of the present disclosure, the rectifier assembly 220 is also physically mounted (e.g., by welding or another suitable bonding mechanism) to an exposed surface of the PCB mounting / communication element 210.

[0044] The PCB-based secondary winding 212 has similarities to other PCB-based fixed planar inductor or transformer designs. However, the RT's PCB-based secondary winding has two different features compared to the fixed planar transformer. Specifically, the primary core must have a considerable gap to accommodate the secondary PCB structure; and the primary and secondary windings are physically separated, which means that the conventionally used interleaving between the primary and secondary windings is not feasible for RT PCB-based applications. Therefore, the traditional design of multi-strand PCB-based windings results in significantly high losses in RT applications. Figures 3 to 10 An optimized multi-strand PCB-based winding design and optimization method is described, which can be operated to minimize losses and temperature rise.

[0045] Known PCB-based secondary winding configurations for RT applications experience high copper losses due to skin effect, proximity effect, and eddy current losses. Large gaps in the ferrite core can lead to significantly high leakage flux, further increasing losses and causing temperature rise in the PCB. Splitting the copper winding traces into multiple parallel paths reduces skin effect and eddy current losses. However, conventional winding designs using parallel traces suffer from unbalanced inductance between the twisted current paths and cause unbalanced losses and hot spots in the PCB.

[0046] At HF, the current in the winding conductor tends to concentrate near the outer boundary of the conductor, which is called the skin effect. The skin effect is characterized by the skin depth, which is expressed as Equation-1 ( Figure 3), where ρ is the resistivity of the material, f is the operating frequency, and μ is the magnetic permeability of the material. If the skin depth is much smaller than the conductor size, the effective resistivity of the conductor becomes high due to current crowding near its outer boundary and results in high losses. Copper is widely used as a winding material in winding designs, including PCB-based winding designs. Considering conventional engineering constraints, RTs are conventionally operated between operating frequencies of about 20 kHz to about 100 kHz. From Equation -1 ( Figure 3 ), it can be seen that the skin depth of copper is about 0.206 mm at about 100 kHz and about 0.461 mm at about 20 kHz. In order to greatly reduce the skin effect, the width and thickness of the conductor should be less than twice the skin depth 2δ. Therefore, for a stranded conductor design, each of the copper strands should be narrow and thin enough to reduce the skin effect. For example, at about 100 kHz, the thickness and width of the copper winding / trace should be less than about 0.4 mm.

[0047] Gap (e.g. Figure 4 The gap 434 shown in FIG. 4 is maintained at RT (eg, Figure 4 400) of a portion of the core (eg, Figure 4 The gap is large enough to accommodate the thickness of the rotating PCB board and the gap (i.e., air gap) between the PCB board and the ferrite core for free rotation. The gap can be expressed using Equation-2 ( Figure 3 ), where t pcb is the thickness of the PCB, and t air is the gap between the PCB and the core. The air gap is assumed to be essentially the same on both sides of the PCB. Significantly higher circulating currents appear on the traces near the gap due to higher leakage flux. Therefore, from a magnetic point of view, lower r g Provides lower leakage flux and, therefore, lower eddy current losses in the PCB. However, from a mechanical point of view, a minimum value of PCB thickness is required to operate the PCB at high rotational speeds, which may be up to about 25,000 revolutions per minute (RPM) or even higher. Similarly, a minimum air gap is required between the PCB and the core to maintain the required spacing, taking into account vibration, manufacturability, mounting tolerances, and high-speed deformation of the PCB. Gap t g Typically varies from about 3 mm to about 10 mm, depending on the PCB material, operating speed, mechanical tolerances, operating temperature, and the like. With such a magnetic gap, the leakage flux near the air gap may be very high, and the PCB winding traces will need to be designed and optimized accordingly to minimize eddy currents. The disclosed embodiments, design methods, and resulting structures of thickness, width, and location of individual traces are optimized to minimize eddy currents, losses, and temperature rise in the PCB.

[0048] Fig. 7AAn example of a PCB 710 is depicted with an "untwisted" 6-turn winding (T1, T2, T3, T4, T5, T6) with an unbalanced induction between two strands (Strand-1 and Strand-2). Fig. 7A In the diagram, it can be observed that due to the lower radius of strand-1 per turn, the total length of strand-1 will be less than the length of strand-2. Hence, the resistance and inductance of strand-1 will be less than strand-2. Due to this, the total current of the turns will be unequally distributed between strand-1 and strand-2, with strand-1 carrying a higher current than strand-2. Hence, the losses and temperature of strand-1 will be higher than strand-2. This phenomenon worsens with increasing number of strands per turn, which results in a greater difference between the radii of the outer strands compared to the inner strands.

[0049] In an embodiment of the present disclosure, a stranded twist winding is disclosed that balances the mean length per strand (MLS) and the current between the strands of the winding. Each of the strands is designed to minimize the losses and maximum temperature of the PCB-based coil winding. The proposed design and optimization methods minimize the skin effect, proximity effect, and eddy current losses due to leakage magnetic fields, adjacent turns, and cross-coupling between strands. The number of PCB layers, the thickness of the PCB, the thickness of the inner and outer copper layers, the number of strands per turn, the width and position of each strand are sensitive design and optimization parameters. Figures 4 to 10 Details of a design method according to aspects of the present disclosure are depicted. The number of layers and the copper thickness in each layer are two design parameters used herein to minimize the losses and temperature of the PCB. The maximum thickness of the copper layer is limited by the skin depth effect. At about 100kHz, the copper thickness can be as high as about 15Oz, and for about 20kHz, it can be even thicker. However, thicker copper layers are challenging and costly to manufacture. On the other hand, if a lower copper thickness, such as 4Oz, is chosen, a higher number of layers can be implemented to manufacture the PCB in a cost-effective manner. As the number of PCB layers increases, the number of strands per turn increases proportionally, and this reduces the losses in the PCB. However, the maximum number of layers is limited by the structural integrity of the PCB.

[0050] Figure 4A portion of RT 400 according to aspects of the present disclosure is depicted. RT 400 includes a rotatable PCB 410, a secondary winding 412 integrated with the rotatable PCB 410, a primary winding 126A, a ferrite core 432, and a gap 434, configured and arranged as shown. The loss and temperature rise of the PCB secondary winding 412 are sensitive to the position and width of the twisted wires T1 to T6, the number of twisted wires per turn, and the thickness of the copper layer of the PCB 410. All turns can have the same number of twisted wires or different numbers of twisted wires, depending on their relative position and overall loss distribution in the PCB. For example, a higher number of twisted wires is beneficial to the turns near the gap compared to the turns away from the gap. Figure 4 RT 400 shown depicts a 6-turn PCB design with 5 twisted wires per turn. Traces are placed on only two of the PCB layers. Two additional layers (not shown) are required to implement twists T1-T2, T2-T3, T4-T5, and T5-T6. Trace width and trace position are optimized for this design. Results show that the width of the twisted wire closer to gap 434 is much narrower than the width of the twisted wire farther from gap 434. Figure 5 Equation-3 is depicted, which is an optimization equation according to aspects of the present disclosure. Using Equation-3, the strands of PCB 410 are optimized to minimize the total power loss in PCB 410, minimize the peak temperature rise of PCB 410, and keep the traces away from gap 434. In general, Equation-3 is an optimization objective function. The objective function set in the modeling software explores different design configurations to minimize the total power loss and peak temperature rise while keeping the traces away from the air gap as much as possible. Therefore, Equation-3 can be used in computer system 1100 ( Fig.11 The optimization goal is achieved by using the modeling software running on the computer (as shown in FIG. 1 ).

[0051] Both the width (W) and position (P) of the traces can be optimized. During the optimization process, the width of each of the strands can be input as an optimization parameter. However, this can significantly increase the optimization time as processing time increases. Fig. 6A , Figure 6B and Figure 6C An example optimization method according to aspects of the present disclosure is depicted. In addition, the number of layers and the thickness of each layer are two optimization parameters used to determine the overall loss and temperature rise of the PCB 410 in embodiments of the present disclosure. Fig. 6A Trace T1 is depicted, illustrating an example in which both the position (P) and width (W) of each strand in each layer are considered as optimization parameters. Figure 6B Another example of trace T1 is depicted, showing an example where both the position (P) and width (W) of each strand on a layer are considered as optimization parameters. Strands of the same turn in parallel layers are copies of the optimization layer. This approach significantly simplifies the optimization. Figure 6CAnother example of trace T1 is depicted, which shows an example where the position (P) of each strand on a layer is considered as an optimization parameter. The width (W) of all strands is the same. This approach further simplifies the optimization method.

[0052] The torsion function associated with aspects of the present disclosure will now be described. The winding design according to aspects of the present disclosure can be divided into two topologies. The first topology is multiple turns per layer in a spiral arrangement, while the second topology has only one turn, where multiple strands are placed on each layer. With respect to the first topology, torsion can be introduced at different locations of the winding to balance the current between the strands in the winding. Fig. 7A An axisymmetric cross-sectional view of a PCB 710 with 6 turns is shown, where the winding has two strands. The six circular turns are wound as T1-T2-T3-T4-T5-T6. In order to make the average length per strand (MLS) approximately the same, the present disclosure proposes a turn-to-turn twist between the strands. For example, if the relative positions of the strands are as follows Figure 7B 720 of PCB 720, the MLS of strand-1 and strand-2 will be approximately the same. This reversal of the relative strand position is referred to herein as a "twist". Twist can be introduced at different locations of the winding. For example, the following torsion options provide a balanced MLS in the following system. For option 1, two torsions are applied - one between T1 and T2; and another between T4 and T5. For option 2, two torsions are applied - one between T2 and T3; and another between T4 and T5. For option 3, four torsions are applied - one between T1 and T2; one between T4 and T5; one between T2 and T3; and one between T4 and T5. For option 4, one torsion is applied between T3 and T4.

[0053] As the number of turns increases, the options for twisting to balance the MLS between the strands increase. Of the four twisting options mentioned above, the fourth option has a technical advantage over the others. When the trace moves from one side of the PCB to the other, a balanced MLS can be achieved with only one twist from T3 to T4, which is at the middle turn. In addition, this configuration does not require an additional PCB layer for the twist, while the other options (options 1-3) require two additional layers in the PCB to implement the twist. Similarly, when there are only two strands, the twist-twist sequence has only one option, which reverses the position of strand-1 and strand-2. As the number of strands increases, the options for repositioning the strands also increase. The sequence of reversing all strands is referred to herein as "full twist" (an example of which is in Fig. 8A ), and repositioning a portion of the strand is referred to herein as partial twisting (an example of which is shown in Figure 8B). When the strands per turn span more than one layer, the options and flexibility of partial twists become even higher. As with full twists, the same MLS can be achieved by applying multiple partial twists, which can be beneficial when placing vias (extending from one PCB layer to another) in the PCB design to physically achieve the twist.

[0054] As previously noted herein, the winding design according to aspects of the present disclosure can be divided into two topologies. The first topology is multiple turns per layer in a spiral arrangement, while the second topology is only one turn, with multiple strands placed on each layer. With respect to the second topology, Fig. 9 A PCB 910 is depicted having a winding design configured and arranged to include one turn (10 strands) on each layer, with a twist introduced between turn-3 and turn-4. This twist can be introduced without using any additional layers. For PCB 910, each layer contains one turn. A full twist is introduced between turn-3 and turn-4, which balances the inductance and MLS of the strands. This design does not require any additional layers to accommodate the twist. The twist can be applied sequentially as the trace descends from layer 3 to layer 4. The MLS can be balanced with only one twist for even and odd twists. Alternatively, instead of one twist, two or more twists can be applied to achieve easier MLS balancing. The location, width and thickness of the traces, and the number of layers are followed Figures 4 to 6C The proposed optimization method shown and described previously herein is the subject of optimization.

[0055] Fig.10is a diagram showing an example of how a twisting operation can be implemented from a first layer of a PCB to a second lower layer of the PCB using vias according to aspects of the present disclosure. As shown, at the first layer, strand-1 is physically and electrically coupled to via-1; strand-2 is physically and electrically coupled to via-2; strand-3 is physically and electrically coupled to via-3; strand-4 is physically and electrically coupled to via-4; strand-5 is physically and electrically coupled to via-5; and strand-6 is physically and electrically coupled to via-6. Via-1 transitions strand-1 from the first layer of the PCB to the second layer of the PCB, and further changes strand-1 from occupying a first position and an outermost position in the first layer to occupying a sixth position and an innermost position in the second layer of the PCB. Via-2 transitions strand-2 from the first layer of the PCB to the second layer of the PCB, and further changes strand-2 from occupying a second position in the first layer to occupying a fifth position in the second layer of the PCB. Via-3 transitions strand-3 from the first layer of the PCB to the second layer of the PCB, and further changes strand-3 from occupying the third position in the first layer to occupying the fourth position in the second layer of the PCB. Via-4 transitions strand-4 from the first layer of the PCB to the second layer of the PCB, and further changes strand-4 from occupying the fourth position in the first layer to occupying the third position in the second layer of the PCB. Via-5 transitions strand-5 from the first layer of the PCB to the second layer of the PCB, and further changes strand-5 from occupying the fifth position in the first layer to occupying the second position in the second layer of the PCB. Via-6 transitions strand-6 from the first layer of the PCB to the second layer of the PCB, and further changes strand-6 from occupying the sixth position in the first layer to occupying the first position in the second layer of the PCB.

[0056] Therefore, it can be seen from the foregoing detailed description that the integrated mounting and / or communication structure (e.g., PCB) described herein provides technical advantages and technical effects. The secondary winding and rectifier subsystem are assembled in the same PCB structure, which significantly simplifies the design, prototype development, and production of the associated RT. The embodiments of the present disclosure also reduce or eliminate the termination and interconnection difficulties between the rectifier and secondary winding assemblies. The embodiments of the present disclosure also allow the assembly area (e.g., the assembly area that accommodates the diodes of the rectifier) ​​to be directly mounted on the motor shaft using an aluminum support sleeve, which provides high mechanical robustness and simpler thermal management. Therefore, according to aspects of the present disclosure, the integrated mounting and communication structure implements a motor design that prioritizes compact size; reduced cost; simplification of electrical, mechanical, and thermal design; and reduced eddy current losses.

[0057] Fig.11An example of a computer system 1100 that can be used to implement computer-based components according to aspects of the present disclosure is shown. The computer system 1100 includes an exemplary computing device ("computer") 1102, which is configured to perform various aspects of the content-based semantic monitoring operations described herein according to aspects of the present disclosure. In addition to the computer 1102, the exemplary computer system 1100 also includes a network 1114, which connects the computer 1102 to additional systems (not depicted) and can include one or more wide area networks (WANs) and / or local area networks (LANs), such as the Internet, one or more intranets, and / or one or more wireless communication networks. The computer 1102 and the additional systems communicate via the network 1114, for example, transferring data between them.

[0058] The exemplary computer 1102 includes a processor core 1104, a main memory ("memory") 1110, and one or more input / output components 1112, which communicate via a bus 1103. The processor core 1104 includes a cache memory ("cache") 1106 and controls 1108, which include branch prediction structures and associated search, hit, detection, and update logic, which will be described in more detail below. The cache 1106 may include multiple cache levels (not depicted) on-chip or off-chip from the processor 1104. The memory 1110 may include various data stored therein, such as instructions, software, routines, etc., which may be passed to / from the cache 1106, for example, via controls 1108, for execution by the processor 1104. The one or more input / output components 1112 may include one or more components that facilitate local and / or remote input / output operations to / from the computer 1102, such as a display, keyboard, modem, network adapter, etc. (not depicted).

[0059] The cloud computing system 50 is in wired or wireless electronic communication with the computer system 1100. The cloud computing system 50 can supplement, support or replace some or all functions (in any combination) of the computer system 1100. In addition, some or all functions of the computer system 1100 can be implemented as nodes of the cloud computing system 50.

[0060] Various winding optimization and torsion design operations may be implemented by a computer aided design (CAD) system operable to perform calculations, circuit modeling, and circuit simulation operations according to aspects of the present disclosure. According to aspects of the present disclosure, the previously described CAD system may be implemented using computer system 1100 ( Fig.11) to run a CAD software application operable to perform the various calculations and algorithms described herein.

[0061] For ease of illustration and explanation, the various components / modules of the system shown herein are depicted separately. In embodiments of the present disclosure, the functions performed by the various components / modules / models may be distributed differently than shown without departing from the scope of the various embodiments of the present disclosure described herein, unless otherwise explicitly stated.

[0062] The terms used herein are for the purpose of describing specific embodiments only and are not intended to be limiting. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements parts and / or groups thereof.

[0063] The figures described herein are illustrative. There may be many variations of the figures or the steps (or operations) described therein without departing from the spirit of the present disclosure. For example, actions may be performed in different orders, or actions may be added, deleted or modified. In addition, the term "coupling" describes having a signal path between two elements, and does not imply a direct connection between elements, without intermediate elements / connections therebetween. All of these variations are considered to be a part of the present disclosure.

[0064] The following definitions and abbreviations will be used in the interpretation of the claims and specification. As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," "contains," or "containing" or any other variation thereof are intended to cover a non-exclusive inclusion. For example, a composition, mixture, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, mixture, process, method, article, or apparatus.

[0065] Additionally, the term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or designs. The terms "at least one" and "one or more" are understood to include any integer greater than or equal to one, i.e., one, two, three, four, etc. The term "plurality" is understood to include any integer greater than or equal to two, i.e., two, three, four, five, etc. The term "connected" may include both indirect "connections" and direct "connections."

[0066] The terms "about," "substantially," "approximately," and variations thereof are intended to include the degree of error associated with measurement of a particular quantity based on the equipment available at the time the application was filed. For example, "about" may include a range of ±8% or 5% or 2% of a given value.

[0067] Aspects of the present disclosure may be embodied as systems, methods and / or computer program products at any possible level of technical detail integration. A computer program product may include a computer-readable storage medium (or multiple media) having computer-readable program instructions thereon for causing a processor to perform aspects of the present disclosure.

[0068] A computer readable storage medium may be a tangible device capable of retaining and storing instructions for use by an instruction execution device. A computer readable storage medium may be, for example, but not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of computer readable storage media includes the following: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as a punch card or a raised structure in a groove, having instructions recorded thereon, and any suitable combination of the foregoing. Computer-readable storage media as used herein should not be interpreted as transient signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses transmitted through fiber optic cables), or electrical signals transmitted through wires.

[0069] The flowcharts and block diagrams in the figures illustrate the architecture, functions and operations of possible implementations of the systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagram may represent a module, segment or portion of an instruction, which includes one or more executable instructions for implementing one or more specified logical functions. In some alternative embodiments, the functions indicated in the blocks may appear outside the order indicated in the figure. For example, two blocks shown in succession may actually be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order, depending on the functions involved. It will also be noted that each block illustrated in the block diagram and / or flowchart, and the combination of blocks in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system that performs a specified function or action or performs a combination of dedicated hardware and computer instructions.

[0070] Although the present disclosure has been described with reference to one or more exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made and equivalents may be substituted for its elements without departing from the scope of the present invention. In addition, many modifications may be made to adapt specific circumstances or materials to the teachings of the present disclosure without departing from its essential scope. Therefore, it is intended that the present invention is not limited to the specific embodiments disclosed as the best mode contemplated for carrying out the present invention, but that the present invention will include all embodiments falling within the scope of the claims.

Claims

1. A rotary transformer (RT), comprising: Printed circuit board (PCB); and A set of secondary windings integrated with the PCB; wherein the set of secondary windings comprises a plurality of traces extending over a first region of the PCB and a second region of the PCB; wherein the plurality of traces are organized in a first positional order in a first region of the PCB; and Wherein, the plurality of traces are organized in a second positional order in a second region of the PCB.

2. The RT according to claim 1, wherein: The PCB also includes a first trace of the plurality of traces.

3. The RT according to claim 2, wherein: A first trace in the plurality of traces has a first positional location in the first positional sequence.

4. The RT according to claim 3, wherein: A first trace of the plurality of traces has a second positional location in the second positional sequence.

5. The RT according to claim 4, wherein: A first position location in the first position sequence is different from a second position location in the second position sequence.

6. The RT according to claim 5, wherein: The RT also includes a first through-via element.

7. The RT according to claim 6, wherein: A first end of the first via element is physically and electrically coupled to a first trace of the plurality of traces in the first region.

8. The RT according to claim 7, wherein: A second end of the first via element is physically and electrically coupled to a first trace of the plurality of traces in the second region.

9. The RT according to claim 8, wherein: The first region includes a first layer of the PCB; and The second region includes a second layer of the PCB.

10. The RT of claim 1, wherein: Each of the plurality of traces includes a plurality of strands; Each strand of the plurality of strands comprises a width (W) and a position (P) within its associated trace; W and P are optimized to minimize inductor losses; and W and P are further optimized to minimize the peak temperature of the PCB.

11. A method of manufacturing a rotary transformer (RT), the method comprising: forming a printed circuit board (PCB); and forming a set of secondary windings integrated with the PCB; wherein the set of secondary windings comprises a plurality of traces extending over a first region of the PCB and a second region of the PCB; wherein the plurality of traces are organized in a first positional order in a first region of the PCB; and Wherein, the plurality of traces are organized in a second positional order in a second region of the PCB.

12. The method according to claim 11, wherein: The PCB also includes a first trace of the plurality of traces.

13. The method according to claim 12, wherein: A first trace in the plurality of traces has a first positional location in the first positional sequence.

14. The method according to claim 13, wherein: A first trace of the plurality of traces has a second positional location in the second positional sequence.

15. The method according to claim 14, wherein: A first position location in the first position sequence is different from a second position location in the second position sequence.

16. The method of claim 15, further comprising forming a first through-hole element of the PCB.

17. The method according to claim 16, wherein: A first end of the first via element is physically and electrically coupled to a first trace of the plurality of traces in the first region.

18. The method according to claim 17, wherein: A second end of the first via element is physically and electrically coupled to a first trace of the plurality of traces in the second region.

19. The method of claim 18, wherein: The first region includes a first layer of the PCB; and The second region includes a second layer of the PCB.

20. The method of claim 11, wherein: Each of the plurality of traces includes a plurality of strands; Each strand of the plurality of strands comprises a width (W) and a position (P) within its associated trace; W and P are optimized to minimize inductor losses; and W and P are further optimized to minimize the peak temperature of the PCB.

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