Parameter-free synthesis of zero-impedance converter
First Claim
1. A method for parameter free synthesizing electric motor drive system of infinite disturbance rejection ratio and zero order dynamics including parameter free zero impedance converter comprising:
- accepting a source of electrical energy of a constant voltage at an input to a power converter,coupling mechanically a shaft of an electric motor to a load to be driven at an output,controlling a power flow from said input to said output,modulating said power converter for the control of said power flow in a pulse width modulation manner,supplying a total control signal for modulating said power converter,supplying a voltage feedback signal from a voltage applied to said electric motor,feeding back said voltage feedback signal through a voltage feedback circuit in a negative feedback loop with respect to a direct path signal,supplying an input velocity command obtained as a differentiated input position command,passing said input velocity command through a direct path circuit;
thereby producing said direct path signal,passing said input velocity command through a feedforward circuit;
thereby producing a feedforward signal,passing a voltage error signal, obtained as the algebraic sum of said direct path signal and said voltage feedback signal fed through said voltage feedback circuit, through a forward circuit;
thereby producing a forward control signal proportional to the algebraic sum of said direct path signal and said voltage feedback signal,sensing a current through said electric motor,passing the sensed current signal through a buffering circuit;
thereby producing a buffered current sense signal,passing said buffered current sense signal through a current sense gain circuit;
thereby producing a processed current sense signal,measuring continuously and in real time a true root mean square value of said processed current sense signal;
thereby producing a true root mean square value of said processed current sense signal,supplying a sensed back electromotive force signal,sensing an angular shaft speed of the motor by a tach and passing the tach signal through a tach gain circuit;
thereby producing said sensed back electromotive force signal,subtracting said sensed back electromotive force signal from a voltage sense signal in a voltage algebraic summing circuit;
thereby producing an instantaneous resultant voltage,sensing said voltage applied to said electric motor;
thereby producing said voltage sense signal,measuring continuously and in real time a true root mean square value of said instantaneous resultant voltage;
thereby producing a true root mean square value of said instantaneous resultant voltage,measuring continuously and in real time a phase of said buffered current sense signal;
thereby producing a buffered current sense signal phase,measuring continuously and in real time a phase of said total control signal;
thereby producing a control signal phase,dividing said true root mean square value of said instantaneous resultant voltage with said true root mean square value of said processed current sense signal;
thereby producing a magnitude of real part of current feedback transfer function,subtracting said buffered current sense signal phase from said total control signal phase;
thereby producing a phase of real part of current feedback transfer function,multiplying in a current feedback circuit magnitude of said buffered current sense signal by a value of said magnitude of real part of current feedback transfer function and shifting in said current feedback circuit the phase of buffered current sense signal for a value of said phase of real part of current feedback transfer function;
thereby producing a processed current feedback signal,feeding back said processed current feedback signal in a positive feedback loop with respect to said forward control signal and said feedforward signal and summing the three signals,supplying said total control signal, obtained as the sum of said forward control signal and said feedforward signal and said processed current feedback signal, for modulating said power converter for the control of the flow of power from the input electrical source to the output mechanical load, whereby impedance of said electric motor is being forced to zero making an angular shaft position and speed independent of said load in a parameter free manner with respect to the impedance parameters and making a transfer function form the input position command to the angular shaft position a constant and therefore of zero order in said parameter free manner.
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Abstract
A method of synthesizing a system which forces finite value of an impedance to zero comprising a positive current feedback of a prescribed functionalism and a negative voltage feedback to ensure stability of the system. The prescribed functionalism of the current loop uses arithmetic elements as well as voltage and current measurements to provide for a parameter-free synthesis of the converter whereby the converter operates in the measurement-based mode, the measured variables being the voltage and the current associated with the impedance of interest, without a need to supply values of both resistive and reactive components of the impedance of interest. The converter is used in synthesizing electric motor drive systems, incorporating any kind of motor, of infinite disturbance rejection ratio and zero-order dynamics and without specifying the resistive and the inductive values of the motor impedance.
21 Citations
18 Claims
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1. A method for parameter free synthesizing electric motor drive system of infinite disturbance rejection ratio and zero order dynamics including parameter free zero impedance converter comprising:
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accepting a source of electrical energy of a constant voltage at an input to a power converter, coupling mechanically a shaft of an electric motor to a load to be driven at an output, controlling a power flow from said input to said output, modulating said power converter for the control of said power flow in a pulse width modulation manner, supplying a total control signal for modulating said power converter, supplying a voltage feedback signal from a voltage applied to said electric motor, feeding back said voltage feedback signal through a voltage feedback circuit in a negative feedback loop with respect to a direct path signal, supplying an input velocity command obtained as a differentiated input position command, passing said input velocity command through a direct path circuit;
thereby producing said direct path signal,passing said input velocity command through a feedforward circuit;
thereby producing a feedforward signal,passing a voltage error signal, obtained as the algebraic sum of said direct path signal and said voltage feedback signal fed through said voltage feedback circuit, through a forward circuit;
thereby producing a forward control signal proportional to the algebraic sum of said direct path signal and said voltage feedback signal,sensing a current through said electric motor, passing the sensed current signal through a buffering circuit;
thereby producing a buffered current sense signal,passing said buffered current sense signal through a current sense gain circuit;
thereby producing a processed current sense signal,measuring continuously and in real time a true root mean square value of said processed current sense signal;
thereby producing a true root mean square value of said processed current sense signal,supplying a sensed back electromotive force signal, sensing an angular shaft speed of the motor by a tach and passing the tach signal through a tach gain circuit;
thereby producing said sensed back electromotive force signal,subtracting said sensed back electromotive force signal from a voltage sense signal in a voltage algebraic summing circuit;
thereby producing an instantaneous resultant voltage,sensing said voltage applied to said electric motor;
thereby producing said voltage sense signal,measuring continuously and in real time a true root mean square value of said instantaneous resultant voltage;
thereby producing a true root mean square value of said instantaneous resultant voltage,measuring continuously and in real time a phase of said buffered current sense signal;
thereby producing a buffered current sense signal phase,measuring continuously and in real time a phase of said total control signal;
thereby producing a control signal phase,dividing said true root mean square value of said instantaneous resultant voltage with said true root mean square value of said processed current sense signal;
thereby producing a magnitude of real part of current feedback transfer function,subtracting said buffered current sense signal phase from said total control signal phase;
thereby producing a phase of real part of current feedback transfer function,multiplying in a current feedback circuit magnitude of said buffered current sense signal by a value of said magnitude of real part of current feedback transfer function and shifting in said current feedback circuit the phase of buffered current sense signal for a value of said phase of real part of current feedback transfer function;
thereby producing a processed current feedback signal,feeding back said processed current feedback signal in a positive feedback loop with respect to said forward control signal and said feedforward signal and summing the three signals, supplying said total control signal, obtained as the sum of said forward control signal and said feedforward signal and said processed current feedback signal, for modulating said power converter for the control of the flow of power from the input electrical source to the output mechanical load, whereby impedance of said electric motor is being forced to zero making an angular shaft position and speed independent of said load in a parameter free manner with respect to the impedance parameters and making a transfer function form the input position command to the angular shaft position a constant and therefore of zero order in said parameter free manner. - View Dependent Claims (2, 3, 5, 6, 7, 8)
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3. The method of claim 2 wherein said current feedback circuit in said positive feedback loop is physically implemented using an arithmetic multiplier circuit followed by a phase shifting circuit.
- 5. The method of claim 1 wherein said direct path circuit is synthesized using an equation providing transfer function of said direct path circuit
- space="preserve" listing-type="equation">K.sub.i =mK.sub.m K.sub.e
in said equation m being a scaling constant equal to said transfer function from the input position command to the angular shaft position, Km being a back electromotive force constant characterizing production of a back electromotive force proportional to said angular shaft speed of said electric motor, and Ke being a voltage gain of a voltage feedback circuit.
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6. The method of claim 5 wherein said equation providing transfer function of said direct path circuit is physically implemented, thereby implementing said direct path circuit, as a constant gain circuit.
- 7. The method of claim 1 wherein said feedforward circuit is synthesized using an equation providing transfer function of said feedforward circuit
- space="preserve" listing-type="equation">K.sub.1 '"'"'=mK.sub.m /A
in said equation m being a scaling constant equal to said transfer function from the input position command to the angular shaft position, Km being a back electromotive force constant characterizing production of a back electromotive force proportional to said angular shaft speed of said electric motor, and A being a voltage gain of a pulse width modulation control and power stage.
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4. The method of clam 3 wherein said arithmetic multiplier circuit multiplies magnitude of a buffered current sense signal by a value of the magnitude of real part of current feedback transfer function and said phase shifting circuit shifts phase of said buffered current sense signal for a value of the phase of real part of current feedback transfer function.
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9. A method for parameter free synthesizing electric motor drive system of infinite disturbance rejection ratio and zero order dynamics including parameter free zero impedance converter comprising:
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accepting a source of electrical energy of a constant voltage at an input to a power converter, coupling mechanically a shaft of an electric motor to a load to be driven at an output, controlling a power flow from said input to said output, modulating said power converter for the control of said power flow in a pulse width modulation manner, supplying a total control signal for modulating said power converter, supplying position feedback pulses, feeding back said position feedback pulses and comparing their frequency and phase with frequency and phase of position command pulses in a phase frequency detector in a negative feedback manner;
thereby producing a position error voltage proportional to a difference in frequency and phase between said position command pulses and said position feedback pulses,supplying a position command obtained as a voltage, passing said position command through a position direct path circuit;
thereby producing said position command pulse,passing said position command through a differentiation circuit;
thereby producing a velocity signal voltage,passing said velocity signal voltage through a velocity direct path circuit;
thereby producing a velocity command voltage,passing said velocity signal voltage through a feedforward circuit;
thereby producing a feedforward signal,supplying a velocity feedback signal, feeding back said velocity feedback signal in a negative feedback loop with respect to said velocity command voltage and said position error voltage and summing them;
thereby producing a resulting error voltage,passing said resulting error voltage through a cascade connection of a stabilizing network and a control circuit;
thereby producing a control signal proportional to the algebraic sum of said velocity command voltage and said velocity feedback signal and said position error voltage,sensing a current through said electric motor, passing the sensed current signal through a buffering circuit;
thereby producing a buffered current sense signal,passing said buffered current sense signal through a current sense gain circuit;
thereby producing a processed current sense signal,measuring continuously and in real time a true root mean square value of said processed current sense signal;
thereby producing a true root mean square value of said processed current sense signal,supplying a sensed back electromotive force signal, sensing an angular shaft sped of the motor by a tach and passing the tach signal through a tach gain circuit;
thereby producing said sensed back electromotive force signal,subtracting said sensed back electromotive force signal from a voltage sense signal in a voltage algebraic summing circuit;
thereby producing an instantaneous resultant voltage,sensing a voltage applied to said electric motor;
thereby producing said voltage sense signal,measuring continuously and in real time a true root mean square value of said instantaneous resultant voltage;
thereby producing a true root mean square value of said instantaneous resultant voltage,measuring continuously and in real time a phase of said buffered current sense signal;
thereby producing a buffered current sense signal phase,measuring continuously and in real time a phase of said total control signal;
thereby producing a total control signal phase,dividing said true root mean square value of said instantaneous resultant voltage with said true root mean square value of said processed current sense signal;
thereby producing a magnitude of real part of current feedback transfer function,subtracting said buffered current sense signal phase from said total control signal phase;
thereby producing a phase of real part of current feedback transfer function,multiplying in a current feedback circuit magnitude of said buffered current sense signal by a value of said magnitude of real part of current feedback transfer function and shifting in said current feedback circuit the phase of buffered current sense signal for a value of said phase of real part of current feedback transfer function;
thereby producing a processed current feedback signal,feeding back said processed current feedback signal in a positive feedback loop with respect to said control signal and said feedforward signal and summing them, supplying said total control signal, obtained as the sum of said control signal and said feedforward signal and said processed current feedback signal, for modulating said power converter for the control of the flow of power from the input electrical source to the output mechanical load, whereby impedance of said electrical motor is being forced to zero making an angular shaft position and speed independent of said load in a parameter free manner with respect to the impedance parameters and making a transfer function from said position command to said angular shaft position a constant and therfore of zero order in said parameter free manner. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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11. The method of claim 10 wherein said current feedback circuit in said positive feedback loop is physically implemented using an arithmetic multiplier circuit followed by a phase shifting circuit.
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12. The method of claim 11 wherein said arithmetic multiplier circuit multiplies magnitude of a buffered current sense signal by a value of the magnitude of real part of current feedback transfer function and said phase shifting circuit shifts phase of said buffered current sense signal for a value of the phase of a real part of current feedback transfer function.
- 13. The method of claim 9 wherein said position direct path circuit is synthesized using an equation providing transfer function of said position direct path circuit
- space="preserve" listing-type="equation">K.sub.i =mK.sub.enc K.sub.g
in said equation m being a scaling constant equal to said transfer function from said position command to said angular shaft position, Kenc being a gain constant of a digital encoder, and Kg being a gear ratio constant of a gear box.
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14. The method of claim 13 wherein said equation providing transfer function of said position direct path circuit is physically implemented, thereby implementing said position direct path circuit, as a constant gain circuit.
- 15. The method of claim 9 wherein said velocity direct path circuit is synthesized using an equation providing transfer function of said velocity direct path circuit
- space="preserve" listing-type="equation">K.sub.i '"'"'=mK.sub.v
in said equation m being a scaling constant equal to said transfer function from said position command to said angular shaft position, and Kv being a gain constant of a tach.
- space="preserve" listing-type="equation">K.sub.i "=mK.sub.m /A
Specification