# US 2019/0356261 A1 · Variable frequency independent speed motor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0356261 A1 - Document ID: US20190356261A1 - Status: Published application - Kind: A1 - Application number: 15/982,470 - Filed: 2018-05-17 - Published: 2019-11-21 - Earliest claimed: 2018-05-17 - Assignees: The Boeing Company - Applicants: The Boeing Company - Inventors: Lijun Gao; Shengyi Liu - Web page: https://patentgrep.com/patent/US20190356261A1 ## CPC - H02P 9/14: by variation of field (H02P9/08, H02P9/10 take precedence) - H02P 27/085: {wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency} - H02M 7/003: {Constructional details, e.g. physical layout, assembly, wiring or busbar connections} - H02M 7/4807: {having a high frequency intermediate AC stage} - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) ## Abstract An electric motor apparatus may include a rotor and a stator. The apparatus may include a main field motor stage having a set of stator armature windings positioned on the stator and a set of main field windings positioned on the rotor, where the set of stator armature windings is configured to receive a main multiphase power signal from an alternating current power bus having a first current that causes a first rotating magnetic flux that rotates relative to the stator, where the set of main field windings is configured to receive a secondary multiphase power signal having a second current that causes a second rotating magnetic flux that rotates relative to the rotor, and where a combination of the first rotating magnetic flux and the second rotating magnetic flux causes the rotor to turn at a predetermined reference frequency. ## Claims ### Claim 1 An electric motor apparatus, comprising: a rotor; a stator; a high frequency transformer stage for transmitting an excitation signal from the stator to the rotor, the high frequency transformer stage having a first set of transformer windings positioned on the stator and a second set of transformer windings positioned on the rotor; and a main field motor stage having a set of stator armature windings positioned on the stator and a set of main field windings positioned on the rotor and coupled directly to the second set of transformer windings, wherein the set of stator armature windings is configured to receive a main multiphase power signal from an alternating current power bus having a first current that causes a first rotating magnetic flux that rotates relative to the stator, wherein the set of main field windings is configured to receive a secondary multiphase power signal from the second set of transformer windings, the secondary multiphase power signal having a second current that causes a second rotating magnetic flux that rotates relative to the rotor, wherein a combination of the first rotating magnetic flux and the second rotating magnetic flux causes the rotor to turn at a predetermined reference frequency, and wherein the excitation signal includes a high frequency modulation signal component and a secondary multiphase power component, and wherein an inductance at the second set of transformer windings and the set of main field windings filters the high frequency modulation signal component to form the secondary multiphase power signal. ### Claim 2 (depends on 1) The apparatus of claim 1, further comprising: a motor control unit including an inverter configured to generate the excitation signal based on pulse-width modulation signals. ### Claim 3 (depends on 2) The apparatus of claim 2, further comprising: an encoder, wherein the motor control unit is configured to: generate an electric phase signal based on the main multiphase power signal; receive a rotor phase signal from the encoder; generate a combination phase signal based on a difference between the electric phase signal and the rotor phase signal; and generate the pulse-width modulation signals based on the combination phase signal to control the inverter to generate the excitation signal. ### Claim 4 (canceled) ### Claim 5 (depends on 3) The apparatus of claim 3, wherein the motor control unit is further configured to: receive a reference frequency signal from, the reference frequency signal representing the predetermined reference frequency; generate a Q-axis current signal based on the reference frequency signal and a rotor frequency signal; generate a Q-axis voltage signal based on the Q-axis current signal and a Q-axis feedback current signal; receive a D-axis reference current signal from the motor control unit; generate a D-axis current signal based on the D-axis reference current signal and a D-axis feedback current signal; and generate an alpha-beta voltage signal by applying the combination phase signal in an inverse-Park transform using the Q-axis voltage signal and the D-axis current signal as inputs to the inverse-park transform, wherein the pulse-width modulation signals are derived from the alpha-beta voltage signal at a pulse-width modulation generator circuit. ### Claim 6 (depends on 5) The apparatus of claim 5, wherein the motor control unit is further configured to: filter the excitation signal to retrieve a rotor feedback current signal; generate an alpha-beta current feedback signal by applying a Clarke transformation using the rotor feedback current signal as an input to the Clark transformation; and generate the D-axis feedback current signal and the Q-axis feedback current signal by applying the combination phase signal in a Park transformation using the alpha-beta current feedback signal as an input to the Park transformation. ### Claim 7 (Canceled) ### Claim 8 (canceled) ### Claim 9 (depends on 1) The apparatus of claim 1, wherein the predetermined reference frequency of the rotor is independent from a frequency of the main multiphase power signal. ### Claim 10 (depends on 1) The apparatus of claim 1, wherein the first set of transformer windings, the second set of transformer windings, the set of main field windings, and the set of stator armature windings each include three windings for operation with 3-phase power signals. ### Claim 11 (depends on 1) The apparatus of claim 1, wherein a frequency of the excitation signal is between about 1 kHz to 1 MHz. ### Claim 12 A system comprising: a motor control unit including an inverter configured to generate an excitation signal having a high frequency modulation signal component and a secondary multiphase power component; and a motor comprising: a rotor; a stator; a high frequency transformer stage for transmitting the excitation signal from the stator to the rotor, the high frequency transformer stage having a first set of transformer windings positioned on the stator and a second set of transformer windings positioned on the rotor; and a main motor stage having a set of stator armature windings positioned on the stator and a set of main field windings positioned on the rotor, wherein the set of stator armature windings is configured to receive a main multiphase power signal from an alternating current power bus having a current that causes a first rotating magnetic flux that rotates relative to the stator, wherein an inductance between the second set of transformer windings and the set of main field windings filters the high frequency modulation signal component to form a secondary multiphase power signal, and wherein the set of main field windings is configured to receive the secondary multiphase power signal, the secondary multiphase power signal having a current that causes a second rotating magnetic flux that rotates relative to the rotor, wherein a combination of the first rotating magnetic flux and the second rotating magnetic flux causes the rotor to turn at a predetermined reference frequency. ### Claim 13 (depends on 12) The system of claim 12, wherein the motor control unit comprises: a rectifier configured to rectify the main multiphase power signal from the alternating current power bus to generate a direct current power signal; a controller circuit; and a frequency converter including the inverter, wherein the controller circuit is configured to control the frequency converter to modulate the direct current power signal to generate the excitation signal. ### Claim 14 (canceled) ### Claim 15 (depends on 13) The system of claim 13, wherein the controller circuit is configured to: generate an electric phase signal based on the main multiphase power signal; receive a rotor phase signal from an encoder; generate a combination phase signal based on a difference between the electric phase signal and the rotor phase signal; and generate pulse-width modulation signals based on the combination phase signal to control the inverter to cause the secondary multiphase power signal to have a frequency, magnitude, and phase that enables the first rotating magnetic flux and the second rotating magnetic flux to combine to turn the rotor at the predetermined reference frequency. ### Claim 16 (depends on 15) The system of claim 15, wherein the controller circuit is further configured to: receive a reference frequency signal, the reference frequency signal representing the predetermined reference frequency; generate a Q-axis current signal based on the reference frequency signal and a rotor frequency signal; generate a Q-axis voltage signal based on the Q-axis current signal and a Q-axis feedback current signal; receive a D-axis reference current signal; generate a D-axis current signal based on the D-axis reference current signal and a D-axis feedback current signal; and generate an alpha-beta voltage signal by applying the combination phase signal in an inverse-Park transform using the Q-axis voltage signal and the D-axis reference current signal as inputs to the inverse-park transform, wherein the pulse-width modulation signals are derived from the alpha-beta voltage signal. ### Claim 17 (depends on 16) The system of claim 16, wherein the controller circuit is further configured to: filter the excitation signal to retrieve a rotor feedback current signal; generate an alpha-beta current feedback signal by applying a Clarke transformation using the rotor feedback current signal as an input to the Clark transformation; and generate the D-axis feedback current signal and the Q-axis feedback current signal by applying the combination phase signal in a Park transformation using the alpha-beta current feedback signal as an input to the Park transformation. ### Claim 18 A method comprising: receiving a main multiphase power signal at a set of stator armature windings coupled to a stator of a motor apparatus, the main multiphase power signal having a current that causes a first rotating magnetic flux that rotates relative to the stator; transferring an excitation signal from the stator to a rotor using a high frequency transformer stage that includes a first set of transformer windings coupled to the stator and a second set of transformer windings coupled to the rotor, wherein the excitation signal includes a high frequency modulation signal component and a secondary multiphase power component; receiving a secondary multiphase power signal at a set of main field windings coupled to the rotor of the motor apparatus and coupled directly to the second set of transformer windings, wherein an inductance between the second set of transformer windings and the set of main field windings filters the high frequency modulation signal component to form the secondary multiphase power signal, the secondary multiphase power signal having a current that causes a second rotating magnetic flux that rotates relative to the rotor; generating an electric phase signal based on the main multiphase power signal; receiving a rotor phase signal from an encoder configured to monitor rotation of the rotor; generating a combination phase signal based on a difference between the electric phase signal and the rotor phase signal; and generating pulse-width modulation signals based on the combination phase signal to control an inverter to cause the secondary multiphase power signal to have a frequency, magnitude, and phase that enables the first rotating magnetic flux and the second rotating magnetic flux to combine to turn the rotor at a predetermined reference frequency. ### Claim 19 (depends on 18) The method of claim 18, wherein the predetermined reference frequency of the rotor is independent from a frequency of the main multiphase power signal. ### Claim 20 (canceled) ### Claim 21 (depends on 18) The method of claim 18, further comprising: receiving a reference frequency signal, the reference frequency signal representing the predetermined reference frequency; generating a Q-axis current signal based on the reference frequency signal and a rotor frequency signal; generating a Q-axis voltage signal based on the Q-axis current signal and a Q-axis feedback current signal; receiving a D-axis reference current signal; generating a D-axis current signal based on the D-axis reference current signal and a D-axis feedback current signal; and generating an alpha-beta voltage signal by applying the combination phase signal in an inverse-Park transform using the Q-axis voltage signal and the D-axis reference current signal as inputs to the inverse-park transform, wherein the pulse-width modulation signals are derived from the alpha-beta voltage signal. ### Claim 22 (depends on 21) The method of claim 21, further comprising: filtering the excitation signal to retrieve a rotor feedback current signal; generating an alpha-beta current feedback signal by applying a Clarke transformation using the rotor feedback current signal as an input to the Clark transformation; and generating the D-axis feedback current signal and the Q-axis feedback current signal by applying the combination phase signal in a Park transformation using the alpha-beta current feedback signal as an input to the Park transformation. ### Claim 23 (depends on 18) The method of claim 18, wherein a frequency of the excitation signal is between about 1 kHz to 1 MHz. ### Claim 24 The system of cla im 12, wherein the first set of transformer windings, the second set of transformer windings, the set of main field windings, and the set of stator armature windings each include three windings for operation with 3-phase power signals. ### Claim 25 (depends on 12) The system of claim 12, wherein a frequency of the excitation signal is between about 1 kHz to 1 MHz.