System and method for monitoring and control
First Claim
1. A method of monitoring the state of a linearly reciprocating machine comprising an electromechanical transducer in response to an input to the machine by providing an estimate of a value of at least one of a plurality of machine properties including machine variables and machine parameters, the method comprising:
- (a) providing a parametrised model of the machine in which respective model parameters and variables correspond to the plurality of machine properties,(b) providing an input to the model corresponding to a value of an input to the machine,(c) measuring one of the machine variables to provide a measurement thereof,(d) comparing the measurement of one of the machine variables with the corresponding model variable and outputting a measure of a difference between them,(e) optimising the model in an iterative optimisation process by repeatedly varying a plurality of the model parameters corresponding to machine properties while using the same input to the model and comparing the same measurement of one of the machine variables with the corresponding model variable as the plurality of model parameters are varied to reduce the difference,(f) generating a signal representative of an estimate of one of the machine properties other than the measured one of the machine variables based on the value of the model parameter or variable corresponding thereto, and(g) periodically repeating steps (b) to (f) thereby to continuously provide as an output a real-time optimised estimate of the one of the machine properties other than the measured one of the machine variables.
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Accused Products
Abstract
The invention provides for the monitoring and control of a system, such as a linear electro-mechanical transducer, e.g. a linear electric motor, particularly when driven in a reciprocating manner. A dynamic model of the linear motor and its load is used to calculate from the input drive to the motor a predicted response of the motor. The predicted response is compared to a measured response and the model parameters are varied by global optimisation until the two match as closely as desired. The drive may be the voltage input to the electrical motor and the response may be the electrical current in the motor coils. The parameters and variables of the model, after optimisation, can be taken as good estimates of the actual operating parameters and variables of the linear motor. This gives a measurement of such quantities as the stoke and offset of the linear motor. The invention is particularly applicable to the use of linear motors to drive compressors, for instance in Stirling cycle coolers. The system can be applied to balanced pairs of compressors and to compressor systems which use an active balancer to cancel vibration in the system. In this case a balancer model is created and used in an analogous way to the motor model.
38 Citations
44 Claims
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1. A method of monitoring the state of a linearly reciprocating machine comprising an electromechanical transducer in response to an input to the machine by providing an estimate of a value of at least one of a plurality of machine properties including machine variables and machine parameters, the method comprising:
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(a) providing a parametrised model of the machine in which respective model parameters and variables correspond to the plurality of machine properties, (b) providing an input to the model corresponding to a value of an input to the machine, (c) measuring one of the machine variables to provide a measurement thereof, (d) comparing the measurement of one of the machine variables with the corresponding model variable and outputting a measure of a difference between them, (e) optimising the model in an iterative optimisation process by repeatedly varying a plurality of the model parameters corresponding to machine properties while using the same input to the model and comparing the same measurement of one of the machine variables with the corresponding model variable as the plurality of model parameters are varied to reduce the difference, (f) generating a signal representative of an estimate of one of the machine properties other than the measured one of the machine variables based on the value of the model parameter or variable corresponding thereto, and (g) periodically repeating steps (b) to (f) thereby to continuously provide as an output a real-time optimised estimate of the one of the machine properties other than the measured one of the machine variables. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. Apparatus for monitoring a state of a linearly reciprocating machine comprising electromechanical transducer in response to an in put to the machine by providing an estimate of a value of at least one of a plurality of machine properties including machine variables and machine parameters, comprising:
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a parametrised model of the machine in which respective model parameters and variables correspond to the plurality of machine properties, an input for providing to the model a value corresponding to a value of an input to the machine, a sensor for measuring one of the machine variables to provide a measurement of the one of the machine variables, a comparator for comparing the measurement of one of the machine variables with the model variable corresponding to that machine variable to output a measure of a difference between them, an optimiser for optimising the model in an iterative optimisation process by repeatedly varying a plurality of the model parameters corresponding to machine properties while using the same input to the model and comparing the same measurement of one of the machine variables with the corresponding model variable as the plurality of model parameters are varied to reduce the difference, and an output for providing a signal representative of an estimate of one of the machine properties other than the measured one of the machine variables based on the value of the model parameter or variable corresponding thereto, wherein the apparatus is adapted to periodically repeat operation of the sensor, the comparator, the optimiser and the output, thereby to continuously provide as an output a real-time optimised estimate of the one of the machine properties other than the measured one of the machine variables. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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43. A program embodied on a computer-readable medium, the program, when executed, providing a method of monitoring the state of a linearly reciprocating machine comprising an electromechanical transducer in response to an input to the machine by providing an estimate of a value of at least one of a plurality of machine properties including machine variables and machine parameters, the method using a parametrised model of the machine in which respective model parameters and variables correspond to the plurality of machine properties and the method comprising:
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(a) receiving an input to the model corresponding to a value of an input to the machine, (b) receiving a measurement of one of the machine variables, (c) comparing the measurement of one of the machine variables with the corresponding model variable and outputting a measure of a difference between them, (d) optimising the model in an iterative optimisation process by repeatedly varying a plurality of the model parameters corresponding to machine properties while using the same input to the model and comparing the same measurement of one of the machine variables with the corresponding model variable as the plurality of model parameters are varied to reduce the difference, (e) generating a signal representative of an estimate of one of the machine properties other than the measured one of the machine variables based on the value of the model parameter or variable corresponding thereto, and (f) periodically repeating steps (a) to (e) thereby to continuously provide as an output a real-time optimised estimate of the one of the machine properties other than the measured one of the machine variables.
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44. A method of monitoring the state of a linearly reciprocating machine comprising an electromechanical transducer, in response to an input to the machine, by providing an estimate of a value of at least one of a plurality of machine properties including machine variables and machine parameters, the method using a parametrised model of the machine in which respective model parameters and variables correspond to the plurality of machine properties and the method comprising:
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(a) receiving an input to the model corresponding to a value of an input to the machine, (b) receiving a measurement of one of the machine variables, (c) comparing the measurement of one of the machine variables with the corresponding model variable and outputting a measure of a difference between them, (d) optimising the model in an iterative optimization process by repeatedly varying one or more model parameters corresponding to machine properties while using the same input to the model and comparing the same measurement of one of the machine variables with the corresponding model variable as the plurality of model parameters are varied to reduce the difference, (e) generating a signal representative of an estimate of one of the machine properties other than the measured one of the machine variables based on the value of the model parameter or variable corresponding thereto, and (f) periodically repeating steps (a) to (e) thereby to continuously provide as an output a real-time optimised estimate of the one of the machine properties other than the measured one of the machine variables.
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Specification