Multi-phase differential synthesis resolver apparatus
View Patent ↗A novel multi-phase resolver topology and apparatus is provided for measuring a displacement of movement body more precisely and economically. In variable reluctance (VR) resolvers, N coil-poles are placed at N equally spaced positions over one turn of the stator, N being an odd number greater than or equal to 5. Each coil serves both as an excitation and a sensing coil, and all N coils are wound with the same number of turns at an identical electrical polarity. Depending on the installed rotor lobe shape, N sinusoidal or quasi-square waveform displacement signals are sensed on multi-phase resolver, and from which two-phase orthogonal displacement signals are optimally and differentially synthesized. The multi-phase resolver topology and differential synthesis method is also applied to other types of resolvers, such as wound-rotor, inductance, capacitive, and magnetic resolvers.
1. A differential synthesis apparatus adapted to sense a plurality of amplitude modulated phase-delayed displacement signals and outputs amplitude modulated two-phase orthogonal displacement signals,
wherein the differential synthesis apparatus utilizes sine synthesis coefficients and cosine synthesis coefficients being selectable from a Zero-Force transformation, and
wherein the differential synthesis apparatus removes at least one of a common mode noise induced by an external disturbance flux and an unmodulated carrier signal component.
2. The differential synthesis apparatus of claim 1 , wherein the differential synthesis apparatus is realized by an electrical circuitry and comprises:
a differential sine synthesis module implemented in an OP-amp circuitry, wherein the OP-amp circuitry comprises:
an N number of sensing resistors, each connected to a primary differential OP-amp, wherein the N number of sensing resistors are sorted into a group of negative-sign sensing resistors for the negative sine synthesis coefficients and a group of positive-sign sensing resistors for the positive sine synthesis coefficients; and
the primary differential OP-amp, wherein the negative-sign sensing resistors are connected to a negative (−) input port of the primary OP-amp, and the positive-sign sensing resistors are connected to a positive (+) input port of the primary OP-amp,
wherein the negative input port and an output of the primary OP-amp is connected by a primary feedback gain register, while the positive input port and the reference level (ground) is connected by a primary match register such that each resistor value is determined by a ratio between the value of the primary feedback gain resistor and the value of corresponding sine synthesis coefficient under a specific condition that the value of the primary feedback gain register is equal to that of the primary match register,
wherein an un-modulated carrier signal component and common mode noise in a signal, if any included, is removed through the primary differential OP-amp as a common mode noise rejection; and
a differential cosine synthesis module implemented in an OP-amp circuitry, wherein the OP-amp circuitry comprises:
an N number of sensing resistors, each connected to a secondary differential OP-amp, wherein the N number of sensing resistors are sorted into a group of negative-sign sensing resistors for the negative cosine synthesis coefficients and a group of positive-sign sensing resistors for the positive cosine synthesis coefficients; and
the secondary differential OP-amp, wherein the negative-sign sensing resistors are connected to the negative (−) input port of the secondary OP-amp, and the positive-sign sensing resistors are connected to the positive (+) input port of the secondary OP-amp,
wherein the negative input port and the output of the secondary OP-amp is connected by a secondary feedback gain register, while the positive input port and the reference level (ground) is connected by a secondary match register such that each resistor value is determined by the ratio between the value of the secondary feedback gain resistor and the value of a corresponding cosine synthesis coefficient under a specific condition that the value of the secondary feedback gain register is equal to that of the secondary match register,
wherein an un-modulated carrier signal component and common mode noise in a signal, if any included, is removed through the secondary differential OP-amp as a common mode noise rejection.
3. The differential synthesis apparatus of claim 1 , further comprising:
a stator including an N number of magnetic sensors, wherein N being an odd integer greater than or equal to 5, wherein the magnetic sensors being equidistant over a mechanical period or an electrical period of the stator from another magnetic sensor; and
a rotor including a plurality of magnets wherein each turn of the rotor generates at least one electrical period on the stator,
wherein the stator outputs a plurality of phase-delayed displacement signals as the rotor rotates, wherein each one of the displacement signals is sequentially phase-delayed, wherein a plurality of displacement signals are obtained from the N number of magnetic sensors, and wherein the number of the plurality of displacement signal is the same as the N number of magnetic sensors over one mechanical turn of the rotor.
4. The differential synthesis apparatus of claim 1 , further comprising:
a mover including an N number of magnetic sensors, wherein N being an odd integer greater than or equal to 5, wherein the magnetic sensors being equidistant over a mechanical period or an electrical period of the mover from another magnetic sensor; and
a stator including a plurality of magnets wherein a displacement of the mover generates at least one electrical period on the stator,
wherein the mover outputs a plurality of phase-delayed displacement signals as the mover moves, wherein each one of the displacement signals is sequentially phase-delayed, wherein a plurality of displacement signals are obtained from the N number of magnetic sensors, and wherein the number of the plurality of displacement signals is the same as the N number of magnetic sensors over one mechanical turn of the mover.
5. The differential synthesis apparatus according to claim 1 , further comprising:
a phase-sensitive demodulator to demodulate the amplitude modulated two-phase orthogonal displacement signals, and converts them into two-phase orthogonal displacement signals without the carrier; and
an interpolator to determine an absolute position or incremental position of a rotor.
6. The differential synthesis apparatus according to claim 1 , further comprising:
an A/D converter adapted to convert an orthogonal displacement signal into a digital signal and outputs a digital orthogonal displacement signal;
a Hilbert Transformer adapted to shift the carrier phase of the digital orthogonal displacement signal by 90°;
an adder adapted to add the output signal of the Hilbert Transformer and the original signal of which carrier phase is not shifted and outputs an complex signal; and
an absolute calculator adapted to calculate an absolute value of the complex signal and outputs a carrier-removed orthogonal displacement signal.
7. The differential synthesis apparatus according to claim 1 ,
wherein the differential synthesis apparatus outputs amplitude modulated three-phase displacement signals,
wherein the amplitude modulated three-phase displacement signals have phases of 0°, 120°, and 240°,
wherein the differential synthesis apparatus utilizes three sets of synthesis coefficients being selectable from a Zero-Force transformation.