US6883333B2 — Sensorless control of a harmonically driven elect…

Claim 1

Independent Claim 221 words

A method for sensorlessly controlling the operation of a thermoacoustic device including a linear electrodynamic machine communicating with a load device, said method comprising the steps of: providing a thermoacoustic device including a linear electrodynamic machine communicating with a load device through a piston; setting electrical inputs to the electrodynamic machine, the electrical inputs including frequency and either voltage or current; determining a voltage signal at an input of the electrodynamic machine; determining a current signal at the input of the electrodynamic machine; estimating a positional parameter of the piston using the voltage and current signals, the positional parameter being selected from the group consisting of displacement, velocity, and acceleration of the piston; estimating a force parameter of the load device using the positional parameter and the current signal, the force parameter being selected from the group consisting of force and pressure on the piston; using the positional parameter and the force parameter to determine at least one operating condition of the thermoacoustic device, the operating condition being the phase angle between the positional parameter and the force parameter; determining a difference between the at least one operating condition and a desired operating condition; and adjusting at least one electrical input to the electrodynamic machine so as to reduce the difference, the adjusted input being one of frequency, current, and voltage.

Claim 2

Independent Claim 221 words

A method for sensorlessly controlling the operation of a thermoacoustic device including a linear electrodynamic machine communicating with a load device, said method comprising the steps of: providing a thermoacoustic device including a linear electrodynamic machine communicating with a load device through a piston; setting electrical inputs to the electrodynamic machine, the electrical inputs including frequency and either voltage or current; determining a voltage signal at an input of the electrodynamic machine; determining a current signal at the input of the electrodynamic machine; estimating a positional parameter of the piston using the voltage and current signals, the positional parameter being selected from the group consisting of displacement, velocity, and acceleration of the piston; estimating a force parameter of the load device using the positional parameter and the current signal, the force parameter being selected from the group consisting of force and pressure on the piston; using the positional parameter and the force parameter to determine at least one operating condition of the thermoacoustic device, the operating condition being the phase angle between the positional parameter and the force parameter; determining a difference between the at least one operating condition and a desired operating condition; and adjusting at least one electrical input to the electrodynamic machine so as to reduce the difference, the adjusted input being one of frequency, current, and voltage.

Claim 3

Dependent Claim 32 words

The method of claim 1 , further comprising repeating the determining, estimating and adjusting steps until the difference between the at least one operating condition and the desired operating condition is minimized.

Claim 4

Dependent Claim 28 words

The method of claim 1 , further comprising developing a mathematical model of the electrodynamic machine, the estimating steps comprising using the mathematical model to perform the estimating.

Claim 5

Dependent Claim 22 words

The method of claim 1 , wherein determining the current signal comprises measuring the current signal and filtering the measured current signal.

Claim 6

Dependent Claim 47 words

The method of claim 4 , wherein the step of measuring and filtering the current imposes a time delay on the current signal, the method further comprising the step of delaying the voltage signal by a time-delay substantially equal to the time delay on the current signal.

Claim 7

Dependent Claim 22 words

The method of claim 1 , wherein determining the voltage signal comprises measuring the voltage signal and filtering the measured voltage signal.

Claim 8

Dependent Claim 48 words

The method of claim 6 , wherein the step of measuring and filtering the voltage signal imposes a time delay on the voltage signal, the method further comprising the step of delaying the current signal by a time-delay substantially equal to the time delay on the voltage signal.

Claim 9

Dependent Claim 31 words

The method of claim 1 , wherein the steps of determining the voltage and current signals comprise measuring the voltage and current signals and filtering the measured voltage and current signals.

Claim 10

Dependent Claim 21 words

The method of claim 8 , wherein the filtering step comprises filtering the voltage and current signals using substantially identical filters.

Claim 11

Dependent Claim 29 words

The method of claim 1 , wherein the desired operating condition is a 90 degree phase angle between the displacement of the piston and the pressure on the piston.

Claim 12

Dependent Claim 27 words

The method of claim 1 , wherein the desired operating condition is an in-phase relationship between the velocity of the piston and the pressure on the piston.

Claim 13

Dependent Claim 55 words

The method of claim 1 , further comprising the step of providing a control device wherein the control device performs the steps of: determining a difference between the at least one operating condition and a desired operating condition; and adjusting at least one electrical input to the electrodynamic machine so as to reduce the difference.

Claim 14

Dependent Claim 15 words

The method of claim 12 , wherein the control device is a phase locked loop.

Claim 15

Dependent Claim 20 words

The method of claim 1 , wherein the desired operating condition corresponds to an acoustic resonance of the thermoacoustic device.

Claim 16

Dependent Claim 44 words

The method of claim 1 , further comprising setting limits on at least one of the electrical inputs, positional parameters or force parameters, the adjusting step comprising adjusting the at least one electrical input so as not to violate the at least one limit.

Claim 17

Dependent Claim 90 words

The method of claim 1 , wherein the step of estimating the positional parameter comprises estimating the displacement, {circumflex over (x)}, of the piston according to equation x ^ = 1 Bl ⁡ [ ∫ ( v t - iR e ) ⁢ ⅆ t - L e ⁢ i ] . wherein Bl is the transduction coefficient, v t is the voltage signal at the terminals of the machine, i is the current, Re is the stator winding resistance, and Le is the self inductance of the stator windings.

Claim 18

Dependent Claim 114 words

The method of claim 1 , wherein the step of estimating the force parameter comprises estimating the pressure, {circumflex over (p)} a , according to equation p ^ a = 1 A ⁢ ( Bli - M m ⁢ ⅆ 2 ⁢ x ^ ⅆ t 2 - R m ⁢ ⅆ x ^ ⅆ t - K m ⁢ x ^ ) . wherein Bl is the transduction coefficient, i is the current, Mm is the actuator moving mass, {circumflex over (x)} is the estimated displacement of the piston, Rm is the damping constant, Km is the spring constant, and A is the area of a piston in communication with the load device.

Claim 19

Dependent Claim 138 words

The method of claim 1 , wherein the step of estimating the positional parameter comprises estimating the displacement, {circumflex over (x)}, of the piston according to equation x ^ = 1 Bl ⁡ [ ∫ ( v 1 - iR e - ω ⁢ ⁢ L imag ⁢ i ) ⁢ ⅆ t - L e ⁢ i + k 1 ⁢ i 3 + k 2 ⁢ i 5 ] . wherein Bl is the transduction coefficient, v t is the voltage signal at the terminals of the machine, i is the current, Re is the stator winding resistance, L imag is the imaginary component of the inductance of the windings, ω is the operating frequency in radians/sec, Le is the self inductance of the stator windings, and k 1 and k 2 are small, non-complex constants.

Claim 20

Independent Claim 207 words

A method for sensorlessly controlling the operation of a thermoacoustic device including a linear electrodynamic machine communicating with a load device, said method comprising the steps of: providing a thermoacoustic device including a linear electrodynamic machine communicating with a load device through a piston; setting electrical inputs to the electrodynamic machine, the electrical inputs including frequency and either voltage or current; determining a voltage signal at an input of the electrodynamic machine; determining a current signal at the input of the electrodynamic machine; estimating a positional parameter of the piston using the voltage and current signals, the positional parameter being selected from the group consisting of displacement, velocity, and acceleration of the piston; estimating a force parameter of the load device using the positional parameter and the current signal, the force parameter being selected from the group consisting of force and pressure on the piston; using at least the positional parameter and the force parameter to determine at least one operating condition of the thermoacoustic device, the operating condition being selected from the group consisting of efficiency and power; and adjusting at least one electrical input to the electrodynamic machine so as to maximize the operating condition, the adjusted input being one of frequency, current, and voltage.

Claim 21

Independent Claim 207 words

A method for sensorlessly controlling the operation of a thermoacoustic device including a linear electrodynamic machine communicating with a load device, said method comprising the steps of: providing a thermoacoustic device including a linear electrodynamic machine communicating with a load device through a piston; setting electrical inputs to the electrodynamic machine, the electrical inputs including frequency and either voltage or current; determining a voltage signal at an input of the electrodynamic machine; determining a current signal at the input of the electrodynamic machine; estimating a positional parameter of the piston using the voltage and current signals, the positional parameter being selected from the group consisting of displacement, velocity, and acceleration of the piston; estimating a force parameter of the load device using the positional parameter and the current signal, the force parameter being selected from the group consisting of force and pressure on the piston; using at least the positional parameter and the force parameter to determine at least one operating condition of the thermoacoustic device, the operating condition being selected from the group consisting of efficiency and power; and adjusting at least one electrical input to the electrodynamic machine so as to maximize the operating condition, the adjusted input being one of frequency, current, and voltage.

Claim 22

Dependent Claim 32 words

The method of claim 19 , further comprising repeating the determining, estimating and adjusting steps until the difference between the at least one operating condition and the desired operating condition is minimized.

Claim 23

Dependent Claim 28 words

The method of claim 19 , further comprising developing a mathematical model of the electrodynamic machine, the estimating steps comprising using the mathematical model to perform the estimating.

Claim 24

Dependent Claim 22 words

The method of claim 19 , wherein determining the current signal comprises measuring the current signal and filtering the measured current signal.

Claim 25

Dependent Claim 47 words

The method of claim 22 , wherein the step of measuring and filtering the current imposes a time delay on the current signal, the method further comprising the step of delaying the voltage signal by a time-delay substantially equal to the time delay on the current signal.

Claim 26

Dependent Claim 22 words

The method of claim 19 , wherein determining the voltage signal comprises measuring the voltage signal and filtering the measured voltage signal.

Claim 27

Dependent Claim 48 words

The method of claim 24 , wherein the step of measuring and filtering the voltage signal imposes a time delay on the voltage signal, the method further comprising the step of delaying the current signal by a time-delay substantially equal to the time delay on the voltage signal.

Claim 28

Dependent Claim 31 words

The method of claim 19 , wherein the steps of determining the voltage and current signals comprise measuring the voltage and current signals and filtering the measured voltage and current signals.

Claim 29

Dependent Claim 21 words

The method of claim 26 , wherein the filtering step comprises filtering the voltage and current signals using substantially identical filters.

Claim 30

Dependent Claim 42 words

The method of claim 19 , wherein the operating condition is power, the positional parameter is velocity, the force parameter is force, and the power is determined by multiplying the velocity by the force and time averaging the product over a cycle.

Claim 31

Dependent Claim 59 words

The method of claim 19 , wherein the operating condition is efficiency, the positional parameter is velocity, and the force parameter is force, the operating condition determining step further using the voltage and current signals, the efficiency being determined by dividing the product of the force and velocity by the time averaged product of the voltage and current signals.

Claim 32

Dependent Claim 41 words

The method of claim 19 , further comprising the step of providing a control device wherein the control device performs the step of adjusting the at least one electrical input to the electrodynamic machine so as to maximize the operating condition.

Claim 33

Dependent Claim 41 words

The method of claim 19 , further comprising setting limits on at least one of the electrical inputs, positional parameters or force parameters, the adjusting step comprising adjusting the at least one electrical input so as not to violate the limit.

Claim 34

Dependent Claim 89 words

The method of claim 19 , wherein the step of estimating the positional parameter comprises estimating the velocity, {circumflex over (V)} pist t of the piston according to equation V ^ pist = 1 Bl ⁢ ( v t - iR e - L e ⁢ ⅆ i ⅆ t ) wherein Bl is the transduction coefficient, v t is the voltage signal at the terminals of the machine, i is the current, Re is the stator winding resistance, and Le is the self inductance of the stator windings.

Claim 35

Dependent Claim 112 words

The method of claim 19 , wherein the step of estimating the force parameter comprises estimating the force on the load, {circumflex over (f)} load , according to equation f ^ load = Bli - M m ⁢ ⅆ V ^ pist ⅆ t 2 - R m ⁢ V ^ pist - K ⁢ ∫ V ^ pist ⁢ ⅆ t wherein Bl is the transduction coefficient, i is the current, Mm is the actuator moving mass, {circumflex over (x)} is the estimated displacement of the piston, Rm is the damping constant, Km is the spring constant, and A is the area of a piston in communication with the load device.

Claim 36

Dependent Claim 155 words

The method of claim 19 , wherein the step of estimating the positional parameter comprises estimating the displacement, {circumflex over (x)}, and the velocity, {circumflex over (V)} pist of the piston according to equations: x ^ = 1 Bl ⁡ [ ∫ ( v 1 - iR e - ω ⁢ ⁢ L imag ⁢ i ) ⁢ ⅆ t - L e ⁢ i + k 1 ⁢ i 3 + k 2 ⁢ i 5 ] and , V ^ pist = ⅆ x ^ ⅆ t wherein Bl is the transduction coefficient, v t is the voltage signal at the terminals of the machine, i is the current, Re is the stator winding resistance, L imag is the imaginary component of the inductance of the windings, ω is the operating frequency in radians/sec, Le is the self inductance of the stator windings, and k 1 and k 2 are small, non-complex constants.

Claim 37

Independent Claim 239 words

A method for sensorlessly controlling the operation of a system including a reciprocating linear electrodynamic machine harmonically driving a displaceable portion of a load device, said method comprising the steps of: providing a system including a linear electrodynamic machine harmonically driving a displaceable portion of a load device; setting electrical inputs to the electrodynamic machine, the electrical inputs including frequency and either voltage or current; determining a voltage signal at an input of the electrodynamic machine; determining a current signal at the input of the electrodynamic machine; estimating a positional parameter of the load device using the voltage and current signals, the positional parameter being selected from the group consisting of displacement, velocity, and acceleration of the displaceable portion; estimating a force parameter of the load device using the positional parameter and the current signal, the force parameter being selected from the group consisting of force and pressure; using at least the positional parameter and the force parameter to determine at least one operating condition of the system, the operating condition being selected from the group consisting of efficiency, power, phase between the positional parameter and the force parameter, and a ratio between the positional parameter and the force parameter; determining a difference between the operating condition and a desired operating condition; and adjusting at least one electrical input to the electrodynamic machine so as to reduce the difference, the adjusted input being one of frequency, current, and voltage.

Claim 38

Independent Claim 239 words

A method for sensorlessly controlling the operation of a system including a reciprocating linear electrodynamic machine harmonically driving a displaceable portion of a load device, said method comprising the steps of: providing a system including a linear electrodynamic machine harmonically driving a displaceable portion of a load device; setting electrical inputs to the electrodynamic machine, the electrical inputs including frequency and either voltage or current; determining a voltage signal at an input of the electrodynamic machine; determining a current signal at the input of the electrodynamic machine; estimating a positional parameter of the load device using the voltage and current signals, the positional parameter being selected from the group consisting of displacement, velocity, and acceleration of the displaceable portion; estimating a force parameter of the load device using the positional parameter and the current signal, the force parameter being selected from the group consisting of force and pressure; using at least the positional parameter and the force parameter to determine at least one operating condition of the system, the operating condition being selected from the group consisting of efficiency, power, phase between the positional parameter and the force parameter, and a ratio between the positional parameter and the force parameter; determining a difference between the operating condition and a desired operating condition; and adjusting at least one electrical input to the electrodynamic machine so as to reduce the difference, the adjusted input being one of frequency, current, and voltage.

Claim 39

Dependent Claim 32 words

The method of claim 35 , further comprising repeating the determining, estimating and adjusting steps until the difference between the at least one operating condition and the desired operating condition is minimized.

Claim 40

Dependent Claim 28 words

The method of claim 35 , further comprising developing a mathematical model of the electrodynamic machine, the estimating steps comprising using the mathematical model to perform the estimating.

Claim 41

Dependent Claim 27 words

The method of claim 35 , wherein the load device is a thermoacoustic device, and the desired operating condition is an acoustic resonance of the thermoacoustic device.

Claim 42

Dependent Claim 22 words

The method of claim 35 , wherein determining the current signal comprises measuring the current signal and filtering the measured current signal.

Claim 43

Dependent Claim 47 words

The method of claim 39 , wherein the step of measuring and filtering the current imposes a time delay on the current signal, the method further comprising the step of delaying the voltage signal by a time-delay substantially equal to the time delay on the current signal.

Claim 44

Dependent Claim 22 words

The method of claim 35 , wherein determining the voltage signal comprises measuring the voltage signal and filtering the measured voltage signal.

Claim 45

Dependent Claim 48 words

The method of claim 41 , wherein the step of measuring and filtering the voltage signal imposes a time delay on the voltage signal, the method further comprising the step of delaying the current signal by a time-delay substantially equal to the time delay on the voltage signal.

Claim 46

Dependent Claim 31 words

The method of claim 35 , wherein the steps of determining the voltage and current signals comprise measuring the voltage and current signals and filtering the measured voltage and current signals.

Claim 47

Dependent Claim 21 words

The method of claim 43 , wherein the filtering step comprises filtering the voltage and current signals using substantially identical filters.

Claim 48

Dependent Claim 23 words

The method of claim 35 , wherein the desired operating condition is a 90 degree phase angle between the displacement and the pressure.

Claim 49

Dependent Claim 87 words

The method of claim 35 , wherein the step of estimating the positional parameter comprises estimating the displacement, {circumflex over (x)}, according to equation x ^ = 1 Bl ⁡ [ ∫ ( v t - iR e ) ⁢ ⅆ t - L e ⁢ i ] . wherein Bl is the transduction coefficient, v t is the voltage signal at the terminals of the machine, i is the current, Re is the stator winding resistance, and Le is the self inductance of the stator windings.

Claim 50

Dependent Claim 109 words

The method of claim 35 wherein the step of estimating the force parameter comprises estimating the pressure, {circumflex over (p)} a , according to equation p ^ a = 1 A ⁢ ( Bli - M m ⁢ ⅆ 2 ⁢ x ^ ⅆ t 2 - R m ⁢ ⅆ x ^ ⅆ t - K m ⁢ x ^ ) . wherein Bl is the transduction coefficient, i is the current, Mm is the actuator moving mass, {circumflex over (x)} is the estimated displacement of the displaceable portion, Rm is the damping constant, Km is the spring constant, and A is the area of the displaceable portion.

Claim 51

Dependent Claim 138 words

The method of claim 35 , wherein the step of estimating the positional parameter comprises estimating the displacement, {circumflex over (x)}, of the piston according to equation x ^ = 1 Bl ⁡ [ ∫ ( v 1 - iR e - ω ⁢ ⁢ L imag ⁢ i ) ⁢ ⅆ t - L e ⁢ i + k 1 ⁢ i 3 + k 2 ⁢ i 5 ] . wherein Bl is the transduction coefficient, v t is the voltage signal at the terminals of the machine, i is the current, Re is the stator winding resistance, L imag is the imaginary component of the inductance of the windings, ω is the operating frequency in radians/sec, Le is the self inductance of the stator windings, and k 1 and k 2 and small, non-complex constants.

Claim 52

Dependent Claim 41 words

The method of claim 35 , further comprising setting limits on at least one of the electrical inputs, positional parameters or force parameters, the adjusting step comprising adjusting the at least one electrical input so as not to violate the limit.

Claim 53

Independent Claim 211 words

A method for controlling the operation of a system including a reciprocating linear electrodynamic machine harmonically driving a displaceable portion of a load device, said method comprising the steps of: providing a system including a linear electrodynamic machine harmonically driving a displaceable portion of a load device; setting electrical inputs to the electrodynamic machine, the electrical inputs including frequency and either voltage or current; determining a current signal at the input of the electrodynamic machine; determining a positional parameter of the load device, the positional parameter being selected from the group consisting of displacement, velocity, and acceleration of the displaceable portion; estimating a force parameter of the load device using the positional parameter and the current signal, the force parameter being selected from the group consisting of force and pressure; using at least the positional parameter and the force parameter to determine at least one operating condition of the system, the operating condition being selected from the group consisting of efficiency, power and phase between the positional parameter and the force parameter; determining a difference between the operating condition and a desired operating condition; and adjusting at least one electrical input to the electrodynamic machine so as to reduce the difference, the adjusted input being one of frequency, current, and voltage.

Claim 54

Independent Claim 211 words

A method for controlling the operation of a system including a reciprocating linear electrodynamic machine harmonically driving a displaceable portion of a load device, said method comprising the steps of: providing a system including a linear electrodynamic machine harmonically driving a displaceable portion of a load device; setting electrical inputs to the electrodynamic machine, the electrical inputs including frequency and either voltage or current; determining a current signal at the input of the electrodynamic machine; determining a positional parameter of the load device, the positional parameter being selected from the group consisting of displacement, velocity, and acceleration of the displaceable portion; estimating a force parameter of the load device using the positional parameter and the current signal, the force parameter being selected from the group consisting of force and pressure; using at least the positional parameter and the force parameter to determine at least one operating condition of the system, the operating condition being selected from the group consisting of efficiency, power and phase between the positional parameter and the force parameter; determining a difference between the operating condition and a desired operating condition; and adjusting at least one electrical input to the electrodynamic machine so as to reduce the difference, the adjusted input being one of frequency, current, and voltage.

Claim 55

Dependent Claim 18 words

The method of claim 50 , wherein the determining the positional parameter step comprises measuring the positional parameter.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2008-04-25	2008-10-25	2009-04-26	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2012-04-25	2012-10-25	2013-04-26	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2016-04-25	2016-10-25	2017-04-26	$7700.00	Window Closed / Lapsed

Sensorless control of a harmonically driven electrodynamic machine for a thermoacoustic device or variable load

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