Sensorless control of a harmonically driven electrodynamic machine for a thermoacoustic device or variable load
AssigneeThe Penn State Research Foundation
InventorsTony L. Shearer, Robert W. M. Smith, Heath F. Hofmann
Life of this patent
Estimating the term…
Abstract
The present invention provides a method of sensorless control of a linear reciprocating electrodynamic machine used for driving a thermoacoustic device, and/or a similar frequency dependent load. Sensorless control is accomplished by estimating the state of predetermined performance parameters at the linear machine through the use of a system model. Thereafter, the method comprises providing a control means operative to obtain the estimated performance parameters and cause manipulation of at least one input parameter to the linear machine such that desired performance parameters are obtained in view of the estimated performance parameters.
Claims51
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.
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.
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.
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.
Dependencies are inferred from the claim text.