Single substrate resolver/rectifier for brushless wound field synchronous machines
An electrical rotating machine provides an integrated capacitive encoder for control of the stator field and enabling any of reduced size, reduced rotational inertia, and lower cost. The same structure may also support capacitive plates for capacitive power transfer to the rotor.
1. An electrical rotating machine comprising:
a stator for providing a magnetic field;
a rotor providing a second magnetic field mounted for rotation about a rotor axis with respect to the stator and including at least one electrical coil having a coil axis with a component perpendicular to the axis;
a brushless AC power coupler communicating AC power to the rotor from a source stationary to the stator;
a capacitive encoder providing an opposed stationary and rotational support separated by a gap with the rotational support mounted to the rotor and the stationary support stationary to the stator, each of the stationary and rotational supports having respective opposed electrical plates having a capacitive coupling adapted to provide a rotation signal indicating rotation of the rotor with respect to the stator; and
solid-state power conversion circuitry held on the rotational support communicating electrical power between the brushless AC power coupler and the electrical coil.
2. The electrical rotating machine of claim 1 wherein the rotation signal indicates a unique absolute position of the rotor with respect to the stator over 360° of rotation of the rotor with respect to the stator.
3. The electrical rotating machine of claim 2 wherein the rotation signal indicates the unique absolute position of the rotor both when the rotor is stationary with respect to the stator and when the rotor is moving with respect to the stator.
4. The electrical rotating machine of claim 1 wherein the support is a plate extending symmetrically about the rotor axis in a plane perpendicular to the rotor axis.
5. The electrical rotating machine of claim 4 wherein the plate is a polymer substrate clad with conductive traces forming a capacitive plate of the capacitive encoder and electrical interconnections between solid-state components of the solid-state power conversion circuitry.
6. The electrical rotating machine of claim 1 wherein the electrical plate on the rotational support has a variable radial extent causing a periodic variation in capacitance between the electrical plate on the rotational support and at least one electrical plate on the stationary support as a function of rotational position of the rotor with respect to the stator.
7. The electrical rotating machine of claim 1 wherein the opposed stationary and rotational supports further include opposed second electrical plates operating together to conduct electrical power capacitively between the stationary support and the solid-state power conversion circuitry on the rotational support.
8. The electrical rotating machine of claim 7 further including a power source providing AC power through a circuit including the electrical plates, the solid-state power conversion circuitry assembly, and the electrical coil.
9. The electrical rotating machine of claim 7 wherein the opposed stationary and rotational supports further include opposed third electrical plates operating together with the second electrical plates to conduct electrical power capacitively from the stationary support to the solid-state power conversion circuitry on the rotational support.
10. The electrical rotating machine of claim 1 wherein the capacitive encoder includes a drive circuit providing a first and second encoder signal with a first phase and second different phase respectively; and
wherein the capacitive encoder further includes at least two pairs of opposed electrical plates on respective of the stationary and rotational support, the first opposed electrical plates of each pair conducting the first signal and the second opposed electrical plates of each pair conducting the second signal; and
further including a decoder circuit monitoring capacitive coupling and signal phase of the first and second encoder signals to provide the rotation signal indicating a unique position of the rotor with respect to the stator over 360° rotation of the rotor with respect to the stator.
11. The electrical rotating machine of claim 10 wherein the first and second encoder signals have 180° of phase difference.
12. The electrical rotating machine of claim 1 wherein the solid-state power conversion circuitry is positioned near a center of the rotational plate about the rotational axis with respect to the electrical plates which are positioned near an edge of the rotational plate away from the rotational axis with respect to the solid-state power conversion circuitry assembly.
13. The electrical rotating machine of claim 1 wherein the opposed electrical plate on the stationary support provides a set of plate elements independently sensing capacitive coupling to the opposed electrical plate on the rotational support and wherein a number of plate elements is 3N where N is an integer such as to provide a three-phase rotation signal.
14. The electrical rotating machine of claim 13 further including a decoder receiving the three-phase rotation signal to provide a signal indicating rotational direction of the rotor.
15. The electrical rotating machine of claim 1 wherein the solid-state power conversion circuitry is a wave rectifier.
16. The electrical rotating machine of claim 1 wherein the brushless AC power coupler is selected from the group consisting of capacitive couplers and inductive couplers.
17. The electrical rotating machine of claim 1 further including a second brushless AC power coupler communicating AC power to the rotor from a source stationary to the stator, the AC power of the second brushless AC power coupler providing a measuring signal for measurement of capacitive coupling of the capacitive encoder.
18. The electrical rotating machine of claim 17 wherein the second brushless AC power coupler uses a stator winding for inductive coupling.
19. The electrical rotating machine of claim 17 wherein the second brushless AC power coupler is a capacitive coupler.
20. The electrical rotating machine of claim 1 wherein the opposed electrical plate on the stationary support provides a set of plate elements independently sensing capacitive coupling to the opposite electrical plate on the rotational support and wherein a number of plate elements is 4 to provide a quadrature rotation signal.