Rotor current prediction in an electric motor drive with a compensation network only on the stationary side

Abstract

Embodiments of the disclosure provide an electric motor drive system comprising a stationary side, a rotating side, and a sensor system on the stationary side, capable of sensing current on the stationary side and transmitting current-based sensor readings to a control unit. The stationary side further comprises a compensation network. The control unit is capable of performing a rotor current prediction process, which is capable of predicting a rotor current connected to a rotor of the rotating side, at least partially, based on the current-based sensor readings and a parameter of at least one component of the compensation network of the stationary side.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of an earlier filing date from U.S. Provisional Application Serial No. 63 / 333,790, filed April 22, 2022, the entire disclosure of which is incorporated herein by reference. BACKGROUND OF THE INVENTION

[0002] A wound-rotor synchronous machine (WRSM) is an electric motor with a rotor and a stator. The stator is the stationary part of the machine, and the rotor is the rotating part. The stator typically has a multi-phase winding, and the rotor is made with a field winding instead of permanent magnets. The rotor rotates in a magnetic field, and the magnetic field can be generated by the windings or field coils. A field coil is an electromagnet used to generate a magnetic field in an electromagnetic machine, usually a rotating electrical machine such as a motor or generator. It contains a coil of wire through which a current flows. In the case of a machine with field coils, a current must flow in the coils to generate the field; otherwise, no power is transferred to or from the rotor.The process of generating a magnetic field using an electric current is called excitation. Field coils offer the most flexible form of magnetic flux regulation and deregulation, but at the expense of an electric current flow.

[0003] Typically, the rotor windings of a WRSM can be energized or excited using slip ring and brush assembly systems. However, slip ring and brush assembly systems have disadvantages, including inefficiency at high speeds, requiring frequent maintenance, and overall loss due to the high contact resistance between the brush and the slip ring, especially at high speeds.

[0004] To avoid the disadvantages of slip-ring and brush excitation methods, wireless (or contactless) excitation or wireless power transmission systems or techniques have been developed. In general, wireless power transmission uses various technologies to transfer energy using electromagnetic fields (EMFs) without a physical connection. In a wireless power transmission system, a transmitter device driven by electrical power from a power source generates a time-varying EMF that transfers power via mutual inductance (M) across a space to a receiver device. The receiver device uses M to extract power from the EMF and deliver the extracted power to an electrical load. Wireless power transmission provides power to electrical devices when interconnecting wires are impractical, dangerous, or not possible.Wireless power delivery technologies primarily fall into two categories: near-field and far-field. In near-field technologies, the time-varying EMF is generated using a variety of techniques that include resonant inductive coupling. Resonant inductive coupling is the wireless near-field transfer of electrical energy between magnetically coupled coils that are part of a resonant circuit tuned to oscillate at the same frequency as the drive frequency.

[0005] Rotary transformers (RTs) are a type of wireless power transfer system that can be used for the controlled wireless excitation of the rotor windings of a WRSM. An RT performs the same general function as a conventional transformer, with both transferring electrical power from one circuit to another at the same frequency but at different voltages. A conventional transformer operates on the principle of electromagnetic induction, meaning that the electromotive force is induced in the closed circuit due to the surrounding variable magnetic field. An RT differs from a conventional transformer in that the RT geometry is arranged so that the primary and secondary windings can be rotated with respect to each other, with negligible changes in the electrical properties.In one common configuration, the RT can be constructed by winding the primary and secondary windings into separate halves of a pot core. The concentric halves face each other, with each half mounted on one of the parts that rotates relative to each other. Magnetic flux provides the coupling from one half of the pot core to the other across an air gap, thereby providing the "M" that transfers energy from the RT's primary windings to its secondary windings.

[0006] Known methods of using RT systems to provide excitation for a WRSM may include providing a resonant tuning network, also called a compensation network, to the RT system. A resonant tuning network may include circuit components (e.g., various combinations of resistors (R), inductors (L), and / or capacitors (C)) that allow the associated transformer to store oscillating electrical energy similar to a tank circuit and thus act as a bandpass filter, passing frequencies near their resonant frequency from the primary to the secondary winding while blocking other frequencies. The magnitude 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 referred to as LC or LRC resonant circuits because of the inductive (L), resistive (R), and capacitive (C) components used to form the resonant circuit. In materials science, every material has its own natural frequency. When the external vibration equals the natural frequency, resonance occurs. In electrical engineering, the impedance of inductors and capacitors depends on frequency. Capacitive impedance is inversely proportional to frequency, while inductive impedance is directly proportional to frequency. At a certain frequency, the two cancel each other out (or turn each other off). Such a circuit is called a tank circuit, and this particular frequency is the resonant frequency.Additionally, in LC circuits, where the reactance of the L component is essentially the same as the reactance of the C component, the L and C components cancel each other out, meaning that the L and C components compensate or cancel each other out.

[0007] In conventional RT systems that provide resonant tuning or compensation (i.e., an RT compensation system), the resonant tuning network (or compensation network) is provided on the stationary (or stator or primary) side and the rotating (or rotor or secondary) side of the WRSM, respectively. For the primary coil, a basic function of "compensation" is to minimize the input apparent power and / or minimize the voltage-ampere rating (VA) of the network. For the secondary coil, the compensation cancels the leakage inductance of the secondary coil to maximize the transmission capability.

[0008] RT compensation systems that provide resonant circuit components on both the stationary and rotating sides of the WRSM have disadvantages. For example, due to the very limited space and the high operating conditions on the rotating side, which exceed the temperature of commercially available resonant tuning components such as capacitors, it is difficult to place a resonant tuning network or compensation network on the rotating side. Furthermore, with a resonant tuning capacitor on the rotating side, the mechanical reliability of the rotating part decreases and the complexity, mechanical mass, and inertia of the rotating part increase, especially at high speeds.

[0009] For a given torque and speed command in the electric motor, there is a target rotor excitation current that the electric motor drive system requires to be fed into the rotor windings. To monitor and regulate this rotor winding current, a method is needed to monitor the actual rotor excitation current so that the motor's current regulation systems can confirm that the target rotor excitation current has been achieved and is being maintained. A direct method for monitoring the actual rotor excitation current would be to place one or more current sensors at selected locations on the rotor, then configure the sensors with sufficient electronics (such as Internet of Things (IoT) devices) to transmit readings to current regulation systems on the stationary side of the motor.However, for many of the same reasons why it is difficult to place a resonant tuning network or compensation network on the rotating side of a motor, it is also difficult to place a current sensor on a rotating side of a motor and reliably obtain wired or wireless readings from the current sensor when it is rotating at the same rate (e.g., about 22,000 revolutions per minute (RPM)) and is subject to the same high temperatures as the rotor.

[0010] Therefore, there is a need in the art to provide an electric motor drive system with a compensation network and / or rotor current regulation functionality that provides the benefits of compensated RT functionality and / or rotor current sensing without the difficulties associated with providing compensation components and / or rotor current sensors on a rotating side of an electric motor such as a WFSM. SUMMARY OF THE INVENTION

[0011] Embodiments of the disclosure provide an electric motor drive system including a stationary side, a rotating side, and a sensor system on the stationary side operable to sense current on the stationary side and send current-based sensor readings to a controller. The stationary side further includes a compensation network. The controller is operable to perform a rotor current prediction process operable to predict a rotor current associated with a rotating side rotor based at least in part on the current-based sensor readings and a parameter of at least one component of the stationary side compensation network.

[0012] Embodiments of the disclosure provide a method of manufacturing an electric motor drive system that includes forming a stationary side, a rotating side, and a sensor system on the stationary side that is operable to sense current on the stationary side and send current-based sensor readings to a controller. The stationary side further includes a compensation network. The controller is operable to perform a rotor current prediction process that is operable to predict a rotor current associated with a rotating side rotor based at least in part on the current-based sensor readings and a parameter of at least one component of the stationary side compensation network. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a simplified block diagram illustrating a non-limiting example of an electric motor drive system having a rotor winding prediction module in a stationary-side only compensation network in accordance with aspects of the disclosure; Fig. 2 is a simplified block diagram illustrating a non-limiting example of how the Fig. 1 may be implemented in accordance with aspects of the disclosure; Fig. Figure 3 is a simplified block diagram illustrating a non-limiting example of how a control unit of the Fig. 1 may be implemented in accordance with aspects of the disclosure; Fig. 4 is a simplified block diagram showing an equivalent circuit representation of the Fig. 1 and Fig. 2 illustrates the electric motor drive systems shown; Fig. 5 is a simplified block diagram showing another equivalent circuit representation of the Fig. 1 and Fig. 2 illustrates the electric motor drive systems shown; Fig. 6 is a simplified flow diagram illustrating a methodology in accordance with aspects of the disclosure; Fig. 7 illustrates various equations that may be used in performing a rotor winding prediction function of an electric motor drive system with a stationary-side only compensation network in accordance with aspects of the disclosure; Fig. 8 illustrates various equations that may be used in performing a rotor winding prediction function of an electric motor drive system with a stationary-side only compensation network in accordance with aspects of the disclosure; Fig. 9 illustrates various equations that may be used in performing a rotor winding prediction function of an electric motor drive system with a stationary-side only compensation network in accordance with aspects of the disclosure; Fig. 10 illustrates various equations that may be used in performing a rotor winding prediction function of an electric motor drive system with a stationary-side only compensation network in accordance with aspects of the disclosure; Fig. 11 is a simplified flow diagram illustrating a methodology in accordance with aspects of the disclosure; Fig. 12 is a simplified flow diagram illustrating a methodology in accordance with aspects of the disclosure; Fig. 13 is a simplified block diagram showing an equivalent circuit representation of the Fig. 1 and Fig. 2 illustrates the electric motor drive systems shown; Fig. 14 is a simplified block diagram showing another equivalent circuit representation of the Fig. 1 and Fig. 2 electric motor drive systems; and Fig. 15 is a simplified block diagram showing another equivalent circuit representation of the Fig. 1 and Fig. 2 illustrates the electric motor drive systems shown. DETAILED DESCRIPTION OF THE INVENTION

[0013] Embodiments of the disclosure provide a novel rotor winding current prediction technique that can be used in an electric motor drive system with an RT compensation system. In some embodiments of the disclosure, the RT compensation system may be an RT with a novel compensation network on the stationary side only. The electric motor drive system may include an electric motor (e.g., a WRSM) with a stationary side and a rotating side. The novel rotor winding current prediction technique and / or the novel compensation network on the stationary side only, as disclosed herein, address the previously described difficulties associated with placing a rotor winding current sensor and / or a compensation network on the rotating / secondary side.The novel rotor winding prediction technique is configured and arranged to eliminate the need for current sensing and sensor output communication on the rotating side, and the stationary-side-only compensation network is configured and arranged to eliminate the need for compensation components on the rotating side. In some embodiments of the invention, the stationary-side-only compensation network may be implemented as the resonant LCC (inductor-capacitor-capacitor) network on the stationary side only, which is operable to provide tuning only on the stationary side (or primary side) and no compensation elements (e.g., no resonant tuning capacitor element(s)) on the rotating side (or secondary side) for RT compensation system applications.In embodiments described herein, the terms "stationary side only" applied to a compensation network implemented in an electric motor drive system having a stationary side and a rotating side mean that no compensation components are provided on the rotating side.

[0014] In aspects of the disclosure, the previously described electric motor drive system includes a resonant inverter operable to convert direct current (DC) power (e.g., received from a vehicle battery) to radio frequency (RF) AC and provide the RF AC to the resonant LCC network on the stationary side only to wirelessly provide excitation AC to the rotor excitation windings. A rotor rectifier converts the excitation AC to DC excitation and provides it to the rotor windings of the electric motor. The novel rotor winding current prediction technique utilizes features of the resonant LCC on the stationary side only to enable an estimation of the rotor winding current based at least in part on the measurement and analysis of the current generated by the resonant inverter. Embodiments of the disclosure utilize a sensor system on the stationary side only (e.g.,one or more IoT sensors) to provide a measurement of the AC excitation current generated by the resonant converter to a control unit operable to apply a novel winding current prediction technique that predicts the rotor winding current based on a function (e.g., f(C1, C f1 , L f1 , L m , L s1 , in Fig. 3)) of the AC excitation current plus other parameters of the electric motor drive system.

[0015] The stationary-side-only resonant LCC is designed using a novel design methodology that includes calculating the "reflected" coil impedance at the stationary side, which is due to the impedance of the coil on the rotating side of the electric motor. In general, a reflected impedance (or inductance) is the portion of the impedance of a circuit (e.g., circuit A) that is due to the influence of another coupled circuit (e.g., circuit B). The novel design methodology further includes selecting the location and component values ​​of the stationary-side-only resonant LCC network such that the stationary-side-only resonant LCC network tunes the stationary-side-only resonant coil impedance, which is due to the impedance of the coil on the rotating side, in the stationary-side-only resonant LCC network.For example, with a proper location and sizing of a capacitive component of the resonant LCC network only at the stationary side, the windings on the rotating side of the electric motor can be separated from the stationary side by the proper location and sizing of the capacitive component (e.g. the one shown in . Fig. 2) of the resonant LCC tuning network can only be tuned on the stationary side.

[0016] With the configuration of the resonant LCC network only on the stationary side, the primary side coil serves as a load-independent and coupling factor-independent, constant current source. With this property of the resonant LCC network only on the stationary side, the primary coil current does not depend on the rotor current or the relative position of the primary and secondary coils. As a result, the root mean square (RMS) of the inverter output current (which would have active and reactive components) is directly related to the output current of the resonant LCC network only on the stationary side. In the disclosed configuration of the electric motor drive system, no compensation network is used or required on the secondary side. With the high coupling factor and the large L rotor-Inductance eliminates the need for a tuning network. The L2 inductance can be referenced to the primary side and with proper design and sizing of the C1 capacitor (in Fig. 2), the secondary winding can be tuned from the primary side. This configuration of the electric motor drive system is also advantageous compared to the L rotor -Inductance (in Fig. 2) is insensitive because the rotor winding inductance on the DC side of the electric motor (ie downstream of the rotor-side rectifier 210 in Fig. 2) and inductors in steady state operate as short circuits under DC voltages and currents. Thus, the L rotorInductance only introduces a time constant when the current changes from one value to another. Apart from introducing a time constant (inertia with respect to the change in current), this inductance is not reflected on the rectifier input and on the primary side. Therefore, the novel rotor winding current prediction technique is capable of predicting the rotor current by deriving the rotor current as a function of the other system parameters on the stationary side of the converter output current, which is easy to measure, easy to process, and easy to control from the stationary side. In addition, since the LCC tuning on the primary side is configured and arranged so that there is no compensation (e.g., no resonant tuning capacitor (s)) on the secondary side, the tuning circuit on the secondary side is simplified (i.e.,the only tuning element on the secondary side is the secondary windings), the need to identify and deploy a high-temperature capacitor on the rotating side is eliminated, the costs associated with tuning components on the secondary side are eliminated, and the overall reliability of the wireless motor excitation system is improved.

[0017] Turning now to a more detailed description of embodiments of the disclosure, Fig. 1 illustrates a system 100 embodying aspects of the disclosure. System 100 includes a power source 110 electronically coupled to an electric motor drive system 102. Electric motor drive system 102 includes a resonant inverter 120, a DC-excited motor 130, and a controller 150 configured and arranged as shown. In accordance with aspects of the disclosure, DC-excited motor 130 includes a compensation network 140 on the stationary side only and a network of one or more sensors 170 on the stationary side. Further, in accordance with aspects of the disclosure, controller 150 includes a rotor winding current prediction module 160.Although the resonant inverter 120, the DC-excited motor 130, the stationary-side compensation network 140, and the control unit 150 are illustrated as separate components, it is understood that the resonant inverter 120, the DC-excited motor 130, the stationary-side compensation network 140, and the control unit 150 may be configured and arranged in any suitable configuration. For example, the control unit 150 may be incorporated into the resonant inverter 120; the resonant inverter 120 may be incorporated into the DC-excited motor 130; and / or the resonant inverter 120 and the control unit 150 may be incorporated into the DC-excited motor 130.

[0018] The energy source 110 can be implemented in various ways, including, for example, a battery. In some embodiments of the disclosure, the battery can be a battery pack having a set of one or more individual battery cells connected in series or parallel, operating under the control of one or more control units, such as a battery control module (BCM), that monitors and controls the performance of the battery pack. The BCM can monitor several battery pack-level properties, such as pack current, measured by a current sensor, pack voltage, and pack temperature, for example. The battery pack can be recharged from an external power source (not shown). The battery pack can include power conversion electronics operable to condition the power from the external power source to provide the proper voltage and current values ​​for the battery pack.The individual battery cells in a battery pack can be constructed from a variety of chemical formulations. Battery pack chemicals include, but are not limited to, lead acid, nickel cadmium (NiCd), nickel metal hydride (NIMH), lithium-ion, or lithium-ion polymer.

[0019] The resonant inverter 120 is electrically coupled between the power source 110 and the DC-excited motor 130 to transfer excitation energy from the power source 110 to the DC-excited motor 130. Specifically, the resonant inverter 120 is operable to provide energy from the power source 110 at a desired resonant frequency to the compensation network 140 on the stationary side only of the DC-excited motor 130 to provide excitation to the DC-excited motor 140. In embodiments of the disclosure, the resonant inverter 120 is operable to convert the DC voltage from the power source 110 to an AC current at the desired resonant frequency, as required by the DC-excited motor 130 and the compensation network 140 on the stationary side only for motor excitation.In embodiments of the disclosure, the resonant inverter 120 may be a resonant full-bridge inverter with four switches organized as two "phase legs." Each phase leg may include two switches connected in series between a positive DC rail and a negative DC rail. A phase node may be positioned between the two switches of each phase leg to provide the phases of an AC waveform output at a desired resonant frequency. In some embodiments of the disclosure, the resonant inverter 122 generates RF AC power. The controller 150 is electronically coupled to the phase leg switches to control the on / off states of the switches and thereby control the frequency and phase of the AC waveform generated by the resonant inverter 120.The control unit 150 includes a computing device (with memory) that includes a computer, a microprocessor, a digital processor, and the like, that is configured and operative to execute software instructions and programs, and that may include associated firmware such that the control unit 150 is configured and operative to control the on / off switching operations of the resonant inverter 120.

[0020] The control unit 150 is also configured to send various control commands to the DC-excited motor 130, for example, to control the torque and / or speed of the motor 130. To provide precise control commands, the control unit 150 must be able to determine the status of the current (e.g., I rotor) into the rotor windings of motor 130. A direct method for monitoring the actual rotor winding current would be to place one or more current sensors at selected locations on the rotor, then configure the sensors with sufficient electronics (e.g., as IoT devices) to transmit readings to current regulation systems of control unit 150. However, for many of the same reasons why it is difficult to place a resonant tuning network or compensation network on the rotating side of motor 130, it is also difficult to place a current sensor on a rotating side of a motor 130 and reliably obtain wired or wireless readings from a current sensor rotating at the same rate (e.g., about 22,000 RPM) and subject to the same high temperatures as the rotor of motor 130.To address this topic, embodiments of the disclosure configure control unit 150 to include a rotor winding current prediction module 160. In accordance with aspects of the disclosure, control unit 150 receives inverter output current / voltage readings (e.g., I in_o , V inv_o in Fig. 2) from the sensor(s) 170 on the stationary side and uses these, along with other parameters of the system 100, to predict the rotor winding current without having to measure the rotor winding current directly. Additional details of the control unit 150 and the rotor winding current prediction module 160 are shown in Fig. 2-10 and described in more detail below.

[0021] The DC motor 130 can be any electric motor design suitable for the work the motor is required to perform. Examples of work that can be performed by motors in conventional automotive-based motor applications include operating or moving power windows; power seats; fans for the heater and radiator; windshield wipers; and / or the engine of a vehicle with a hybrid electric vehicle configuration. Regardless of the type of DC motor 130, it relies on electromagnetism and reversing magnetic fields to generate mechanical energy. A conventional implementation of the DC motor 130 includes five basic parts: a stator, a rotor, a solid axle, coils, and a squirrel cage.The stator winding in a DC motor is a ring of electromagnets that are paired and energized one after the other, creating the rotating magnetic field. The rotor in a DC motor has no direct connection to a power source and no brushes. Instead, it often uses the squirrel cage rotor described earlier. The squirrel cage rotor in a DC motor is a set of rotor bars connected to two rings, one at each end. The squirrel cage rotor goes into the stator. When excitation power is sent through the stator, it generates an EMF. The squirrel cage bars are conductors and therefore respond to the reversal of the stator's poles, causing the rotor to rotate and generate its own magnetic field. The key to an induction motor, where the rotor's field is induced by the stator's field, is that the rotor is always trying to catch up.It's always searching for stasis, so it rotates to reach that steady state. However, the EMF generated by the stator will always be slightly faster than the rotor's field. The rotor's rotation creates the torque needed to generate the mechanical power to turn a car's wheels or a fan's blades. Some DC motors use a wound rotor (e.g., a WRSM) wrapped with wire rather than a squirrel cage. In any case, there is only one moving part in a DC motor, meaning there are fewer elements to replace or maintain.

[0022] In some embodiments of the disclosure, the DC-excited motor 130 may be a WRSM. A WRSM is a rotating electric motor with a rotor and a stator. The stator is the stationary part of the machine, and the rotor is the rotating part of the machine. The stator typically has a multi-phase winding, and the rotor is equipped with a field winding instead of permanent magnets. The rotor rotates in a magnetic field, and the magnetic field can be generated by the windings or field coils. In a machine with field coils, an excitation current must flow in the coils to generate the field; otherwise, no power is transferred to or from the rotor. Field coils provide the most flexible form of magnetic flux regulation and deregulation, but at the expense of current flow. Conventionally, the rotor winding of a WRSM can be powered or excited using a slip ring and brush assembly.However, slip ring and brush systems have disadvantages, including being inefficient at high speeds, requiring frequent maintenance, and overall lossy due to the high contact resistance between the brush and slip ring systems, especially at high speeds.

[0023] To avoid the disadvantages of slip-ring and brush assembly excitation methods, the stationary-side-only compensation network 140 is incorporated into an RT compensation system (not shown separately from the motor 130) operable to transfer compensated wireless excitation or wireless power from a stator side of the motor 130 to a rotor side of the motor 130. In embodiments of the disclosure, the stationary-side-only compensation network 140 may be implemented as a specially designed stationary-side RT compensation system. In general, the RT is a circuit and method for wirelessly transferring power to the rotor windings of a WRSM for controlled excitation. An 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 different voltage.In general, a conventional transformer operates on the principle of electromagnetic induction, meaning that the electromotive force is induced in the closed circuit by the variable magnetic field surrounding it. An RT differs from a conventional transformer in that the geometry of the RT is arranged so that the primary and secondary windings can be rotated relative to each other with negligible changes in electrical properties. In one common configuration, the RT can be constructed by winding the primary and secondary windings in separate halves of a pot core. The concentric halves face each other, with each half attached to one of the parts that rotate relative to each other.The magnetic flux provides the coupling of one half of the pot core to the other across an air gap, providing "M" which couples energy from the primary windings of the RT to the secondary windings.

[0024] In conventional RT designs that provide resonant tuning or compensation (i.e., an RT compensation system), a resonant tuning network (or compensation network) is provided on both the stationary (or primary) and rotating (or secondary) sides of the WRSM. RT designs that have resonant circuit components on both the stationary and rotating sides of the WRSM are difficult to implement. For example, in practice, it is difficult to place a resonant tuning network or compensation circuit on the secondary side due to the very limited rotor space and the high-temperature operating conditions of the rotor, which exceed the temperature ratings of commercially available compact capacitors.In addition, the placement of a resonant tuning capacitor on the secondary side increases the complexity of the rotating part, increases the mechanical mass, increases inertia and reduces mechanical reliability, especially at high speeds.

[0025] The stationary-side-only compensation network 140 addresses the difficulties associated with actually implementing (i.e., building and using) conventional RT compensation system designs beyond paper designs and computer simulations, and incorporating stationary-side and rotating-side compensation networks by providing the benefits of compensated RT functionality without the difficulties associated with providing a compensation circuit on a rotating side of a DC-excited motor 130 (e.g., a WFSM).In particular, the compensation network 140 is operable only on the stationary side to support the wireless delivery of rotor excitation current from the stationary side to the rotating rotor, thereby eliminating the issues of brush and slip ring maintenance, as well as the inefficiencies, manufacturing challenges, and design disadvantages associated with brush and slip ring systems.

[0026] In aspects of the disclosure, the stationary-side-only compensation network 140 accounts for the missing resonant tuning capacitor on the secondary side by providing an additional resonant tuning capacitor (i.e., one of the resonant tuning capacitors of an LCC network implementation of the stationary-side-only compensation network 140) on the primary side and adjusting the two resonant tuning capacitors on the primary side such that the uncompensated secondary side does not impose any inefficiencies or other disadvantages on the network 140. In embodiments of the disclosure, a stationary-side-only LCC design methodology is provided that includes reflecting the impedance and / or inductance of the secondary side to the primary side, and the leakage inductance of this secondary coil (e.g., L2, in Fig. 2) is tuned at the primary side. In general, a reflected impedance (or inductance) is the portion of the impedance of a circuit (e.g., circuit A) that is due to the influence of another coupled circuit (e.g., circuit B). In embodiments of the disclosure, this can be achieved by deriving the equivalent circuit models of the system 100 as well as the overall impedance model of the system 100, which allows the reflected impedance from the secondary to the primary side to be calculated. A further simplification is applied to the derived equivalent circuit models so that the total impedance observed at the resonant converter 120 can be calculated. To tune this total impedance to a unity power factor, a tuning capacitor (e.g., C1, in Fig. 2) of the LCC design. Thus, the stationary-side-only compensation network 140 eliminates the need for tuning the capacitor on the secondary side and the need for resonant tuning capacitor(s) on the secondary side and their tuning by providing additional tuning components on the primary side (e.g., one or more resonant tuning capacitors) and adjusting the values ​​of the tuning components on the primary side. Additional details of the stationary-side-only LCC design and its associated design methodology in accordance with aspects of the disclosure are described in Fig. 2 and 11-15 and subsequently described here.

[0027] Fig. Figure 2 illustrates a system 100A with a vehicle battery 110A connected by a DC link capacitor (C dc) is electronically coupled to an electric motor drive system 102A. System 100A is a non-limiting exemplary implementation of system 100 (in Fig. 1); the vehicle battery 110A is a non-limiting exemplary implementation of the energy source 110 (in Fig. 1); and the electric motor drive system 102A is a non-limiting exemplary implementation of the electric motor drive system 102 (shown in Fig. 1). The electric motor drive system 102A may be implemented as a resonant inverter 120A that is electronically coupled to the control unit 150 and may be a simplified representation of an electric machine 130A. The resonant inverter 120A is a non-limiting exemplary implementation of the inverter 120 (in Fig. 1). The control unit 150 is operable to include the rotor winding current prediction module 160. The electric machine 130A is an exemplary implementation of the DC-excited motor 130 (in Fig. 1). The electric machine 130A includes a novel resonant LCC only on the stationary side 140A, a network of one or more sensors 170 (e.g., IoT devices), excitation windings L1 on the stationary side, excitation windings L2 on the rotating side, a rectifier 210, and a rotor element represented by a rotor inductance L rotor and a rotor resistance R rotor . The novel stationary-side-only resonant LCC 140A is a non-limiting exemplary implementation of the novel stationary-side-only compensation network 140 (in Fig. 1). The system 100A includes a stationary side (e.g., stator side) 220 and a rotating side (e.g., a rotor side) 230. Generally, the stationary side 220 includes the stator windings L1 and the circuit elements on the left side, and the rotating side 230 includes the stator windings L2 and the circuit elements on the right side. Although the resonant inverter 120A, the electric machine 130A, and the control unit 150 are shown as separate components, it is understood that the resonant inverter 120A, the electric machine 130A, and the control unit 150 can be configured and arranged in any suitable combination of components. For example, the control unit 150 can be incorporated into the resonant inverter 120A; the resonant inverter 120A can be incorporated into the electric machine 130A; and / or the resonant inverter 120A and the control unit 150 may be incorporated into the electric machine 130A.

[0028] Further with reference to Fig. 2, the stationary side 220 is configured to transfer power to the rotating side 230 using inductive power transfer, and the rotating side 230 is configured to receive power from the stationary side 220 using inductive power transfer. The stationary side 220 includes a 110A DC vehicle battery, a DC link capacitor C dc, a resonant inverter 120A, the resonant LCC 140A on the stationary side only, and the coil L1 on the stator side. The resonant inverter 120A receives a DC input signal from the vehicle battery 110A and converts the DC input signal to an AC output signal at a desired resonant frequency. In some embodiments of the disclosure, the resonant inverter 120A is a full-bridge inverter circuit operable to include four power electronic switching devices T1, T2, T3, T4 configured and arranged as shown. The switching devices T1, T2, T3, T4 may be implemented in any suitable format, including, but not limited to, metal-oxide-semiconductor field-effect transistors (MOSFETs), BJTs, FETs, IGBTs, IGFETs, and the like.The control unit 150 is electrically coupled to each of the switching devices T1, T2, T3, T4 to control the switching operation of the resonant inverter 120A. The control unit 150 switches the switching devices T1, T2, T3, T4 on and off to generate the AC output signal Vi. nv_out at the desired resonant frequency. The control unit 150 includes a computing device (with memory) that includes a computer, a microprocessor, a digital signal processor, and the like, configured and operable to execute software instructions and programs, and may include associated firmware, such that the control unit is configured and operable to control the on / off switching operations of the resonant inverter 120A.

[0029] The control unit 150 is also configured to send various control commands to the DC-excited motor 130A, for example, to control the torque and / or speed of the motor 130A. To provide precise control commands, the control unit must be able to determine the status of the current in the rotor windings L rotor of the 130A motor. A direct method for monitoring the actual current in the rotor winding L rotorwould be to place one or more current sensors at selected locations on the rotor, then configure the sensors with sufficient electronics (e.g., as IoT devices) to transmit readings to current regulation systems of the control unit 150. However, for many of the same reasons why it is difficult to place a resonant tuning network or compensation network on the rotating side 230 of the motor 130A, it is also difficult to place a current sensor on a rotating side 230 of a motor 130A and reliably obtain wired or wireless readings from a current sensor rotating at the same rate (e.g., about 22,000 RPM) and subject to the same high temperatures as the rotor of the motor 130A. To address this issue, the control unit 150 is operable to include a rotor winding current prediction module 160.In accordance with aspects of the disclosure, the control unit 150 receives inverter output current / voltage readings (I. inv_ou t, V inv_out ) from the sensor(s) 170 on the stationary side and uses these, together with other parameters of the system 100A, to determine the rotor winding current I rotor predict without changing the rotor winding current I rotor directly. Additional details of the control unit 150 and the rotor winding current prediction module 160 are described in Fig. 3-10 and described in more detail below.

[0030] The resonant LCC 140A on the stationary side only connects the resonant inverter 120A to the coil L1 on the stator side. In the non-limiting exemplary embodiment of the disclosure shown in Fig. 2, the resonant LCC 140A is configured only on the stationary side, an inductor L f1on the stator side, a series capacitor C1 on the stator side (in series with the coil L1 on the stator side) and a parallel capacitor C f1 on the stator side (parallel to the inductor L f1 on the stator side). The series capacitor C1 on the stator side is coupled in series to a positive terminal of the coil L1 on the stator side, and the parallel capacitor C f1 on the stator side is coupled in parallel to the coil L1 on the stator side.

[0031] The rotating side 230 includes a coil L2 on the rotor side that is electrically coupled to a rectifier 210. The coil L2 on the rotor side is sufficiently close to the coil L1 on the stator side to be within an EMF generated by the coil L1 on the stator side, so that M is generated between the coil L1 on the stator side and the coil L2 on the rotor side. The coil L2 on the rotor side uses M to generate an alternating current, and the rectifier 210 converts the alternating current to a direct current (I rotor ). In some embodiments of the disclosure, the rectifier 210 is a bridge rectifier circuit that includes four diodes D1, D2, D3, D4. The direct current is provided to a rotor of the electric machine 130A. The rotor is in Fig. 2 as the inductor L rotor in series with the resistor R rotor shown.

[0032] Energy is transferred through M between coil L1 on the stator side and coil L2 on the rotor side; any L1 / L2 stray inductance has no direct contribution to the active power transfer. Stray inductance can also be undesirable because it causes the voltage to change during charging. In conventional methods for lowering stray inductance and increasing M, a compensating circuit on the rotor side (e.g., a capacitive circuit / capacitive element on the rotor side) is provided on the rotating side 230. However, for applications such as system 100, 100A, where the rotor side rotates with respect to the stator side, it is extremely difficult to manufacture a rotor with a compensating circuit on the rotor side.Embodiments of the disclosure avoid the need for a rotor-side compensation circuit / element by configuring and locating the resonant LCC 140A only on the stationary side, so that compensation that would be provided by a rotor-side compensation circuit / element on the rotating side 230 in conventional RT compensation designs is instead provided by the design and component value settings of the resonant LCC 140A only on the stationary side. Additional details of the resonant LCC 140A only on the stationary side and the associated design methodology in accordance with aspects of the disclosure are provided in . Fig. 3-15 and subsequently described here.

[0033] Fig. Figure 3 illustrates additional details of how the control unit 150 can be implemented as a current / voltage control unit 150A with a rotor winding current prediction module 160A and a current / voltage regulation module 320. The control unit 150A is also configured to send various control commands to the DC-excited motor 130A, for example, to control the torque and / or speed of the motor 130A. To provide accurate control commands, the control unit must be able to determine the status of the current I rotor into the rotor windings L rotorof the motor 130A. To avoid the difficulties associated with placing a current sensor on a rotating side of the motor 130A, and to reliably obtain wired or wireless readings from a current sensor rotating at the same rate (e.g., about 22,000 RPM) and subject to the same high temperatures as the rotor of the motor 130A, the control unit 150A is operable to include the rotor winding current prediction module 160A. In accordance with aspects of the disclosure, the control unit 150A receives inverter output current / voltage readings from the sensor(s) 170 on the stationary side and uses them, along with other parameters of the system 100A (f(C1, C f1 , L f1 , L m , L s1 ) 310) to predict the rotor winding current without having to measure the rotor winding current directly.

[0034] The rotor winding current prediction module 160 uses features of the resonant LCC 140A only on the stationary side to estimate the rotor winding current I rotor based at least in part on the measurement and analysis of the current I inv_out to enable the resonant converter to generate the required current. With the configuration of the resonant LCC network only on the stationary side (140A), the primary side coil L1 serves as a load-independent and coupling factor-independent constant current source. With this property of the resonant LCC network only on the stationary side (140A), the primary coil current is independent of the rotor current or the relative position of the primary and secondary coils L1, L2. As a result, the RMS value (which would have active and reactive components) of the converter output current l inv_outdirectly with the output current of the resonant LCC network 140A only on the stationary side. In the disclosed configuration of the electric motor drive system 100, 100A, no compensation network is used or required on the secondary side. With the high coupling factor and the large L rotor -inductance, the need for a tuning network is eliminated. The L2 inductance can be referenced to the primary side, and with proper design and sizing of the C1 capacitor, the secondary winding can be tuned from the stationary (or primary) side 220. This configuration of the electric motor drive system 102A is also advantageous over the L rotor -Inductance insensitive, since this rotor winding inductance is present on the DC side of the 130A electric motor and inductors in steady state operate as a short circuit under DC voltages and DC currents. Therefore, this inductor (L rotor) only introduces a time constant when the current changes from one value to another. Besides introducing a time constant (inertia with respect to a change in current), this inductance is not reflected in the rectifier input and on the primary side. Therefore, the novel rotor winding current prediction module 160, 160A is capable of predicting the rotor current L rotor by deriving the rotor current L rotor as a function of the other system parameters and the inverter output current I inv_out which is easy to measure from the stationary side, easy to process and easy to control.

[0035] A non-limiting example of the functionality of the control unit 150A and the rotor winding current prediction module 160A is shown in Fig. 4-10 and described in more detail below. Fig. The diagrams and equations presented in Figures 4-10 are provided as a non-limiting implementation example. Therefore, some well-known details related to the equations are briefly mentioned or not provided for the sake of brevity. Referring first to Fig. 4 can be used to switch the system circuit 100A in Fig. 2, a coupled inductor model 100B of the primary and secondary windings L1, L2 with the self-inductances and the leakage inductances of each side 220, 230 as well as the coupling factor are used. The parameters of the coupled inductor model 100B of the rotor transformer windings L1, L2 are defined as follows: L1: Self-inductance on the primary side; L m : Mutual inductance; L s1 : leakage inductance on the primary side; L2: self-inductance on the secondary side; L s2 : Leakage inductance L' s2on the secondary side: secondary leakage inductance, which is related to the primary side; and n: number of turns, n1 / n2. For each side of the transformer, self-inductance is equal to the leakage inductance plus the magnetizing inductance. Therefore, Equations 1 to 8, as shown in Fig. 7. The rectifier output resistance (or rotor winding resistance) can be referenced (or reflected) to the rectifier input, with an equivalent load resistance R L , which is given by equation-9 (in Fig. 8). If this resistance R L When used with the coupled inductor model 100B, the turns ratio between the turns should be taken into account, as shown by equation-10 (in Fig. 8), where R L is the load resistance referenced (or reflected) to the rectifier input; and R' Lis the equivalent load resistance referenced (or reflected) to the stationary (or primary) side 220.

[0036] With the definitions of inductance and load resistance given above, the circuit diagram of system 100A (i.e., electric motor drive system 102A) can now be redrawn as system 100C, which in Fig. 5. As shown in Fig. 5, the rotor current I' RL the difference between the two partial flows, as given by equation-11 (in Fig. 8). Since I Cf1 = U Cf1 × jωC f1 and I m = U m / (jωL m ), the rotor current can be rewritten as equation-12 (in Fig. 8). Here U would be m equal to the U Cf1 -voltage plus the voltage drop across the part that connects C1 and L S1 Therefore, Equation-13 and Equation-14 (in Fig. 8 shown). Here ICf1 by U cf1 × jωC f1 be replaced to create equation-15 (in Fig. 8 shown).

[0037] As in Fig. As shown in Figure 5, the U Cf1 -Voltage as a function of the inverter output voltage minus the voltage drop across the tuning inductor L f1 be written as given by equation-16 (in Fig. 9). This replacement allows U m given by equation-17 (in Fig. 9). Since U m / jωL m necessary for the magnetizing part, equation-18 (in Fig. 9 shown). Once U m / jωL m created, the rotor current can be rewritten as shown in Equation-19 (in Fig. 9). U m / jωL m and U CF1 = V inv0 - I inv0 × jωL mcan be replaced as shown in Equation-20, Equation-21, and Equation-22 (in Fig. 10). Finally, the rotor current is given by equation-23 (in Fig. 10) and / or Equation-24 (in Fig. 10 shown).

[0038] From the example given in Fig. 4-10 shows that IRL' as a function of I invoand other parameters. In the disclosed representation, the rotor current prediction is not dependent on the rotor winding resistance or inductance and is not dependent on an output voltage. While there is a dependence on the inverter output voltage (which would change with the inverter duty cycle or the inverter input voltage), the increase or decrease in rotor current and inverter output current are linearly proportional. Therefore, the disclosed rotor current prediction is not sensitive to the inverter input or output voltage and is not sensitive to changes in the inverter duty cycle. IRL' can be controlled from the input side of the resonant network (inverter output). The relationship between IRL' and I invo is linear. Therefore, IRL' be approximated to a linear equation that uses the inverter output voltage to predict the rotor current. Since the rotating (or rotor) side 230 is an equivalent resistive-inductive load, the rotor current prediction algorithm uses a compensation calculation for improved accuracy. Fig. The equations presented in Figures 1-10 use the first harmonic approximation for the inverter output voltage and current. Embodiments of the disclosure also cover implementing a compensation method to account for the voltage and current harmonics at the inverter output voltage and current.

[0039] Fig. 6 depicts a more general methodology 600 that illustrates how the functionality of the controller 150A and the rotor winding current prediction module 160A may be implemented in accordance with embodiments of the disclosure. The methodology 600 begins at block 602, where the rotor current is made equal to the inverter output current minus the parallel tuning capacitor current minus the magnetized fractional current. At block 604, the parallel tuning capacitor is written as a function of fractional voltage; and the magnetizing current is written as a function of fractional voltage. In block 606, the magnetizing fractional voltage is set equal to the parallel tuning capacitor voltage plus the voltage drop across the series tuning capacitor plus the voltage drop across the primary leakage inductance. At block 608, the parallel tuning capacitor current is replaced by its voltage equation.At block 610, the parallel tuning capacitor voltage is set equal to the inverter output voltage less the voltage drop across the series tuning inductor. At block 612, the resulting equation is converted in terms of the series tuning inductor current. At block 604, the rotor current is converted in terms of the inverter output current and other parameters / values ​​(e.g., f(C1, C). f1 , L f1 , L m , L s1 )) extracted.

[0040] Fig. 11 is a flowchart illustrating a methodology 1100 implemented by the system 100, 100A (in Fig. 1 and Fig. 2). In some embodiments of the invention, portions of the methodology 1100 (e.g., blocks 1112, 1114) may optionally be performed by a computer-aided design (CAD) system running on a processor (e.g., having the same processor functionality as the control unit 150) that is operable to perform calculations, circuit modeling, and circuit simulation operations that may optionally be used to select the compensation component values ​​of the resonant LCC 140A on the stationary side only. In accordance with aspects of the disclosure, the previously described CAD system may be implemented using CAD software applications that are operable to optionally perform the various calculations and algorithms described in Fig. 11-15. Although the description of methodology 1100 refers to components of system 100A, the description applies equally to the corresponding element(s) of system 100.

[0041] As in Fig. As shown in Figure 11, methodology 1100 begins at block 1102 by generating AC. In embodiments of the disclosure, the AC may be RF AC generated using resonant inverter 120A to convert DC received from vehicle battery 110A to the RF AC. At block 1104, the RF AC is received at the novel stationary-side-only compensation / tuning network (e.g., resonant stationary-side-only LCC 140A) connected to primary coils L1.

[0042] Blocks 1112 and 1114 are offline operations that can be used to design the tuning network on the stationary side only (e.g., the resonant LCC 140A on the stationary side only) used in blocks 1104, 1106. At block 1112, the "reflected" coil impedance on the stationary side is calculated, which is due to the impedance of the coil on the rotating side. In some embodiments of the invention, impedance associated with the rotating side coils or primary coils is reflected to the stationary side. In some embodiments of the invention, the impedances associated with the primary coils and the load (as represented by L rotor and R rotor in Fig. 2) to the stationary side. At block 1114, the location and component values ​​of the stationary-side-only tuning network are selected such that the stationary-side-only tuning network tunes the "reflected" coil impedance on the stationary side, which is due to the impedance of the rotating-side coil from the stationary-side-only tuning network. For example, with an appropriate location and sizing of a capacitive component (e.g., the C1 capacitor) of the stationary-side-only tuning network, the rotating-side winding (e.g., L2) can be tuned from the stationary side by the appropriate location and sizing of the capacitive component (e.g., the C1 capacitor) of the stationary-side-only tuning network. Additional details on how blocks 1112 and 1114 may be implemented are described in Fig. 12-15 and described in more detail below.

[0043] Following the operations at block 1104, the methodology 1100 proceeds to block 1106. At block 1106, the tuning network design has compensation components only on the stationary side (e.g., including the two capacitive elements C1, C f1 ), which allow the tuning network only on the stationary side to serve as a load and further serve as an M-independent, constant current source capable of using the AC received at block 1104 to generate an alternating EMF. With this property of the tuning network only on the stationary side (e.g., the resonant LCC 140A only on the stationary side), the coil current on the stationary side (e.g., L1) is not dependent on the rotor current (I rotor) or the relative position of the coils on the stationary side (e.g., L1) and the coil on the rotating side (L2). As a result, the AC generated at block 1102 (e.g., by the resonant converter 120A) has a root-mean-square (RMS) output current (which would have active and reactive components) that is directly related to the output current of the tuning network on the stationary side only. The resulting high M value and the large L rotor -Inductance eliminates the need for a tuning network on the rotating side. The inductance of the inductor on the rotating side (L2) can be referenced to the stationary side or it can be reflected to it and combined with a suitable location and size of a capacitive component (e.g., the C f1-capacitor) of the tuning network only on the stationary side, the winding on the rotating side (e.g. L2) can be separated from the stationary side (e.g. by the appropriate location and size of the capacitive component (e.g. the C f1 -capacitor) of the tuning network only on the stationary side). The resulting system 100, 100A is also compared to the L rotor -Inductance insensitive, since this rotor winding inductance is located on the DC side (ie downstream of the rectifier 210 in Fig. 2) and an inductor in steady state operates as a short circuit under DC voltages and DC currents. Therefore, the L rotor only a time constant is introduced when the current changes from one value to another. Unlike when a time constant is introduced (inertia with respect to the change in current), L rotor not reflected to the input of the rectifier input 210 and to the stationary side 220.

[0044] Following the operations at block 1106, the methodology 1100 proceeds to block 1108. At block 1108, the alternating EMF generated in the rotating-side coil (L2) generates M between L1 and L2, and the rotating-side coil (L2) uses M to generate charging AC current. At block 1110, the charging AC current is converted to a DC current and applied downstream of motor components (e.g., a rotor, in Fig. 2 as L rotor and R rotor shown).

[0045] Fig. 12-15 illustrate a more detailed example of a design methodology for determining the component values ​​of the resonant LCC 140A on the stationary side only for the system 100A, which eliminates the need for a compensation circuit and / or compensation components on the rotating side 230. In particular, Fig. 12 illustrates a design methodology 1200 in accordance with embodiments of the disclosure; and Fig. 13-15 illustrate equivalent circuits and circuit models (systems 100B, 100C, 100D) used in one or more design methodologies in accordance with embodiments of the disclosure.

[0046] With reference to Fig. 12, the methodology 1200 is described with reference to some of the component element designations (e.g., L f1 , C1, C f1 , L1, L2, etc.) used in the equivalent circuits and circuit models (Systems 100B, 100C, 100D) described in Fig. 13-15. As shown in Fig. 12, the methodology 1200 is operable to begin in parallel at blocks 1202 and 1212, then proceed through multiple paths to generate the outputs at blocks 1232 (the primary inductor current, the parallel tuning capacitor current on the primary side, and the voltage across the primary tuning capacitor), 1236 (output voltage and power), 1222 (design of the primary compensation network in accordance with the value of the series tuning capacitor (C1) on the primary side). At block 1202, the methodology 1200 calculates the primary inductor current, the parallel tuning capacitor current on the primary side, and the voltage across the primary tuning capacitor. At block 1204, the methodology 1200 writes Z in as the sum of Z 12 and the inductive reactance of the resonant tuning inductor (L f1 ) on the primary side. At block 1206, the methodology writes 1200 Z 12as the parallel equivalent impedance of Z cf1 and Z1. In embodiments of the disclosure, Z1 is the total equivalent impedance experienced by the inverter. At block 1208, the methodology 1200 writes Z1 as the sum of Z L1 , Z c1 , and Z ref (Equation-6 in Fig. 8) and then provides Z1 to block 1210. Essentially parallel to the operations at blocks 1202-1208, block 1212 calculates the reflected impedance at the secondary side (i.e., the rotating side) Z ref and replaces it in the Z1 equation (equation-6 in Fig. 8) at block 1210.

[0047] Block 1212 also provides its output to block 1214. At block 1214, methodology 1200 sums the reflected impedance of the secondary side with the coil inductance on the primary side and the impedance of the series tuning capacitor. At block 1216, methodology 1200 forms the equivalent impedance circuit of the T-network, calculating partial impedances and the total equivalent impedance experienced by the inverter. At block 1218, methodology 1200 calculates the inverter output current. At block 1220, methodology 1200 designs the series tuning capacitor value on the primary side to significantly eliminate reactive inverter output power. Alternatively, block 1220 can eliminate the imaginary part of the total equivalent impedance experienced by the inverter. At block 1222, methodology 1222 designs the primary compensation network in accordance with the value of the series tuning capacitor on the primary side (C1).

[0048] Returning to block 1210, methodology 1200 continues from block 1210 to block 1230 and calculates Z in , that is, Z1 parallel to Z in . The calculation performed in block 1230 is provided for block 1232 and block 1234. At block 1232, methodology 1200 calculates the primary inductor current, the parallel tuning capacitor current on the primary side, and the voltage across the primary tuning capacitor. At block 1234, methodology 1200 calculates the current on the secondary side using the voltage induced on the secondary side along with the total equivalent impedance of the secondary side. The calculations performed at block 1234 are provided for block 1236, where methodology 1200 calculates the output voltage and power.

[0049] Therefore, from the previous description of Fig. 11-15, it can be seen that the resonant LCC 140A provides technical effects and advantages only on the stationary side. Although C1 is on the stationary side 230, C1 performs a compensation function on the rotating side, which is capable of providing compensation for the L2 windings on the rotating side. This compensation function on the rotating side can be achieved by reflecting the L2 impedance to the stationary side 220, then using the various calculations described in Fig. 8-15 to use the reflected impedance as part of the process for developing the value for C1. In some embodiments of the invention, the impedances associated with the primary coils L2 and the load (as represented by L rotor and R rotor in Fig.2) are reflected to the stationary side and used to develop the values ​​for C1. In some embodiments of the disclosure, in addition to compensating the L2 windings 220 from the stationary side, C1 also compensates for a portion of L1 or the difference between L1 and L f1 together. Therefore, in some embodiments of the disclosure, the value of C1 depends on L2, L1 and L f1 off. C f1 is used to L f1 which provides at least part of the compensation for the L1 windings 220 on the stationary side. In embodiments of the invention, rotor winding current prediction module 160 estimates the rotor current without dependence on any of the parameter values ​​of L f1 , C f1 , and C1.

[0050] The various components / modules of the systems illustrated herein are shown separately for ease of illustration and explanation. In embodiments of the disclosure, the functions performed by the various components / modules / models may be distributed differently than shown here without departing from the scope of the various embodiments of the disclosure described herein, unless expressly stated otherwise.

[0051] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It is further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, acts, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, acts, element components, and / or groups thereof.

[0052] The diagrams presented here are for illustrative purposes only. Many variations of the diagram or the steps (or operations) described therein may exist without departing from the spirit of the disclosure. For example, the actions may be performed in a different order, or actions may be added, deleted, or modified. Also, the term "coupled" describes a signal path between two elements and does not imply a direct connection between the elements without intervening elements / connections. All such variations are considered part of the present disclosure.

[0053] The following definitions and abbreviations are to be used for the interpretation of the claims and the description. As used herein, the terms "comprises," "comprising," "includes," "containing," "has," "comprising," "having," "includes," or "containing" or any other variation thereof are intended to cover non-exclusive inclusion. For example, a composition, mixture, process, method, article, or device that includes a list of elements is not necessarily limited to only those elements, but may also include other elements not expressly listed or pertaining to that composition, mixture, process, method, article, or device.

[0054] 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 to be understood to include any integer greater than or equal to one, i.e., one, two, three, four, etc. The term "a plurality" is to be understood to include any integer greater than or equal to two, i.e., two, three, four, five, etc. The term "connection" can include both an indirect "connection" and a direct "connection."

[0055] The terms "about," "substantially," "approximately," and variations thereof are intended to convey the degree of error associated with a measurement of the particular quantity based on the equipment available at the time of filing the application. For example, "about" may include a range of ± 8%, 5%, or 2% of a given value.

[0056] The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or section of instructions comprising one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions specified in the blocks may occur in a different order than indicated in the figures. For example, two blocks shown in order may actually execute substantially concurrently, or the blocks may sometimes execute in reverse order, depending on the functionality involved.It is also noted that each block of the illustrated block diagrams and / or flowchart, and combinations of blocks in the illustrated block diagrams and / or flowchart, may be implemented by hardware-based special purpose systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

[0057] While the disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood 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 invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, the invention is not intended to be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but the invention is intended to include all embodiments falling within the scope of the claims. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 63 / 333,790

[0001]

Claims

[1] Electric motor drive system comprising: a stationary side; a rotating page; and a sensor system on the stationary side that is operable to detect current at the stationary side and send current-based sensor readings to a control unit; wherein the stationary side comprises a compensation network; and wherein the control unit is operable to perform a rotor current prediction process comprising predicting a rotor current associated with a rotating side rotor based at least in part on the current-based sensor readings and a parameter of at least one component of the stationary side compensation network. [2] The electric motor drive system of claim 1, wherein the stationary side further comprises an inverter operable to convert direct current (DC) received from a power source into alternating current (AC). [3] The electric motor drive system according to claim 2, wherein the current detected by the sensor system on the stationary side comprises the AC. [4] The electric motor drive system of claim 1, wherein the at least one component of the stationary side compensation network comprises a capacitive element. [5] The electric motor drive system of claim 1, wherein the at least one component of the stationary side compensation network comprises an inductive element. [6] The electric motor drive system of claim 5, wherein the at least one component of the stationary side compensation network further comprises a capacitive element. [7] An electric motor drive system according to claim 1, wherein: the compensation network of the stationary side includes a compensation network only on the stationary side (OSS, Only Stationary Side); and the at least one component of the stationary side compensation network comprises a first OSS compensation element of the OSS compensation network. [8] The electric motor drive system according to claim 7, wherein the first OSS compensation element is operable to provide a compensation function on the rotating side. [9] The electric motor drive system of claim 8, wherein a value of the first OSS compensation element is selected to provide the compensation function on the rotating side. [10] An electric motor drive system according to claim 1, wherein: the stationary side comprises a stator with windings on the stationary side; the rotating side comprises the rotor with windings on the rotating side; and the windings on the stationary side are functional to transmit alternating current (AC) excitation signals wirelessly to the windings on the rotating side. [11] A method of manufacturing an electric motor drive system, comprising: Forming a stationary side; Forming a rotating page; and Forming a sensor system at the stationary side that is operable to detect current at the stationary side and send current-based sensor readings to a control unit; wherein the stationary side comprises a compensation network; and wherein the control unit is operable to perform a rotor current prediction process comprising predicting a rotor current associated with a rotating side rotor based at least in part on the current-based sensor readings and a parameter of at least one component of the stationary side compensation network. [12] The method of claim 11, wherein the stationary side further comprises an inverter operable to convert direct current (DC) received from a power source into alternating current (AC). [13] The method of claim 12, wherein the current sensed by the stationary side sensor system comprises the WS. [14] The method of claim 11, wherein the at least one component of the stationary side compensation network comprises a capacitive element. [15] The method of claim 11, wherein the at least one component of the stationary side compensation network comprises an inductive element. [16] The method of claim 15, wherein the at least one component of the stationary side compensation network further comprises a capacitive element. [17] The method of claim 11, wherein: the stationary side compensation network includes a compensation network only on the stationary side (OSS); and the at least one component of the stationary side compensation network comprises a first OSS compensation element of the OSS compensation network. [18] The method of claim 17, wherein the first OSS compensation element is operable to provide a compensation function on the rotating side. [19] The method of claim 18, wherein a value of the first OSS compensation element is selected to provide the compensation function at the rotating side. [20] The method of claim 11, wherein: the stationary side comprises a stator with windings on the stationary side; the rotating side comprises the rotor with windings on the rotating side; and the windings on the stationary side are functional to transmit alternating current (AC) excitation signals wirelessly to the windings on the rotating side.

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