1. An ultrasonic tomograph for measuring characteristics of elementary volumes of a fluid in motion, comprising a plurality of pairs of emitting-receiving ultrasonic probes, whereas each pair may be inscribed on a circle round a flow axis of said fluid, characterised in that each probe comprises means for displacement independently of the other probes on a plane perpendicular to said flow axis.
2. A device according to claim 1, characterised in that it comprises at least one pair of emitting-receiving probes, whereas said first pair may be inscribed on a first circle perpendicular to said flow axis, and a second pair may be inscribed on a second circle forming an angle with the first circle.
3. A device according to claim 2, characterised in that it comprises a ring of variable diameter carrying said first pair of probes on the same plane as said ring, and the second pair of probes outside the plane by means of two parallel arms and of opposite directions.
4. A device according to claim 1, characterised in that it comprises at least two parallel rings and centred round said flow axis, each ring being of variable diameter and carrying at least three pairs of non-coplanar emitting-receiving probes.
5. A device according to claim 4, characterised in that each ring comprises means of spatial displacement.
6. A device according to claim 5, characterised in that the means of displacement comprise three stepping motors along three degrees of liberty.
7. A device according to claim 1, characterised in that the probes comprise piezoelectric ceramic transducers.
8. A device according to claim 1, characterised in that the probes comprise ionic transducers at emission, and capacitive transducers at reception.
9. A device according to claim 1, characterised in that each probe is allocated a stepping motor.
10. A device according to claim 1, characterised in that each pair of probes is composed of a probe which is emitting as well as receiving, connected to a mirror.
11. A device according to claim 1, characterised in that each pair of probes is composed of an emitting probe connected to a plurality of receiving probes.
12. A device according to claim 1, characterised in that it comprises a cylinder whereon is provided a plurality of rings carrying said pairs of probes.
13. System of ultrasonic tomographic measurement for characterisation of a fluid in motion by means of a tomograph according to claim 1, characterised in that it comprises:
means for generating ultrasonic signals to emitting probes of the tomograph,
means for power supplying and controlling the tomograph to manage the displacement of the set of probes of the tomograph,
processing means for capturing and processing the data from the tomograph.
14. A system according to claim 13, characterised in that the means for generating ultrasonic signals comprise a pulse generator.
15. A system according to claim 13, characterised in that the means for generating ultrasonic signals comprise a pulse train generator.
16. A system according to claim 13, characterised in that it comprises moreover an amplifier of said ultrasonic signals.
17. A system according to claim 13, characterised in that the processing means comprise a micro-computer fitted with means for acquisition of data from tomograph and means for digitalising said data.
18. System according to claims 17, characterised in that the micro-computer comprises means to operate said means for generating ultrasonic signals as well as said power supply and control means.
19. A system according to claim 17, characterised in that the micro-computer comprises signal processing means and tomographic processing means.
20. System according to claim 19, characterised in that the micro-computer is connected to display means.
21. An ultrasonic tomographic measuring method, implemented in a system according to claim 13, for characterisation of a fluid in motion, characterised in that around said fluid is placed a ring carrying, diametrically opposite, at least one pair of emitting-receiving probes, said ring forming a tomograph comprising a plurality of pairs of emitting-receiving ultrasonic probes, whereas each pair may be inscribed, diametrally opposite, on a circle centred round a flow axis of said fluid, characterised in that each probe comprises means for displacement on a plane perpendicular to said flow axis; the method comprising the steps of:
a) an ultrasonic signal is sent towards the emitting probe and the signal captured by the receiving probe for a predetermined duration is recovered;
b) the set of probes are pivoted several times by a given angle, and for each pivoting motion step a) is carried out;
c) the centre of rotation of the probes is moved elementarily in a plane XY and the steps a) and b) are carried out;
d) the set of signals captured by the receiving probe is subjected to tomographic processing in order to characterise the fluid in the main plane of the probes.
22. A Method according to claim 21, characterised in that before step b), step a) is repeated for a plurality of different positions of the receiving probe.
23. A method according to claim 21, characterised in that a wide band ultrasonic signal is sent.
24. A method according to claim 23, characterised in that the frequency of the wide band ultrasonic signal ranges substantially between 30kHz and 300KHz.
25. A method according to claim 1, characterised in that one uses a wide aperture emitting probe and several receiving probes arranged in the radiation cone of the emitting probe, and in that one performs an electronic scan to recover the signal captured by each receiving probe.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for modulating a discontinuous conduction mode (DCM) Boost Rectifier having a switchable booster section, the method comprising:
defining a booster section ON time modulation signal having a modulation characteristic according to the following equation:
TON(\u03c6)=f1(\u03c6)+f2(\u03c6)+f3(\u03c6),
where,
\u03c6 defines a phase angle for an input phase voltage of the DCM Boost Rectifier;
TON(\u03c6) defines a modulation characteristic for an ON time of the booster section, and is a continuous function;
f1(\u03c6) defines a first function from 0\u2266\u03c6\u2266\u03c03;
f2(\u03c6) defines a second function from \u03c03\u2266\u03c6\u22662\u03c03;
f3(\u03c6) defines a third function from 2\u03c03\u2266\u03c6\u2266\u03c0; and modulating the switchable booster section using the modulation signal.
2. The method of claim 1, wherein:
the f1(\u03c6) function comprises a linear characteristic;
the f2(\u03c6) function comprises a non-linear characteristic; and
the f3(\u03c6) function comprises a linear characteristic.
3. The method of claim 1, wherein:
f1(\u03c6) and f3(\u03c6) are each triangular functions having a positive peak at \u03c6 equals \u03c06 and 5\u03c06, respectively.
4. The method of claim 1, wherein:
f1(\u03c6) is a linear function having a negative slope and a peak at \u03c6=0; and
f3(\u03c6) is a linear function having a positive slope and a peak at \u03c6=\u03c0.
5. The method of claim 1, wherein:
f2(\u03c6) is a quadratic function having a minimum at \u03c6=\u03c02.
6. The method of claim 1, wherein:
TON(\u03c6) is defined by:
TON(\u03c6)=K*Vdc(\u03c6)\u2212Vmax(\u03c6)0.5,
where,
K defines a factor proportional to the active power to be drawn by the DCM Boost Rectifier;
Vdc defines the output voltage of the DCM Boost Rectifier;
Vmax defines the voltage on the input phase of the DCM Boost Rectifier having the maximum amplitude.
7. The method of claim 6, wherein:
the modulation characteristic shape of TON, as a function of the angle \u03c6, is composed of two triangular portions each having a maximum amplitude defined by coefficient Gp, and by a third harmonic portion having a minimum value defined by coefficient KT, the KT minimum being intermediate the two Gp maximums.
8. The method of claim 7, wherein:
the two triangular portions are defined at phase voltage angles 0\u2266\u03c6\u2266\u03c03 and 2\u03c03\u2266\u03c6\u2266\u03c0, respectively; and
the third harmonic portion is defined at phase voltage angles \u03c03\u2266\u03c6\u22662\u03c03.
9. The method of claim 6, wherein:
the modulation characteristic shape of TON, as a function of the angle \u03c6, is composed of two straight line portions each having a maximum amplitude defined by coefficient Gp, and by a third harmonic portion having a minimum value defined by coefficient KT, the KT minimum being intermediate the two Gp maximums.
10. The method of claim 9, wherein:
the two straight line portions are defined at phase voltage angles 0\u2266\u03c6\u2266\u03c03 and 2\u03c03\u2266\u03c6\u2266\u03c0, respectively; and
the third harmonic portion is defined at phase voltage angles \u03c03\u2266\u03c6\u22662\u03c03.
11. The method of claim 1, further comprising:
providing the modulation signal to a two-switch three level DCM Boost Rectifier.
12. The method of claim 1, further comprising:
providing the modulation signal to a six-switch three level DCM Boost Rectifier.
13. The method of claim 8, further comprising:
providing the modulation signal to a two-switch three level DCM Boost Rectifier.
14. The method of claim 10, further comprising:
providing the modulation signal to a six-switch three level DCM Boost Rectifier.
15. The method of claim 1, further comprising:
performing an iterative analysis on the modulation signal for a specified DCM Boost Rectifier in order to satisfy a defined set of cost functions, thereby defining a quasi-optimal modulation signal; and
wherein the modulating comprises modulating the switchable booster section using the quasi-optimal modulation signal.
16. An apparatus for modulating a discontinuous conduction mode (DCM) Boost Rectifier having a switchable booster section, the apparatus comprising a processor operable in response to executable instructions for:
modulating the switchable booster section using a defined ON time modulation signal having a modulation characteristic according to the following equation:
TON(\u03c6)=f1(\u03c6)+f2(\u03c6)+f3(\u03c6),
where,
\u03c6 defines a phase angle for an input phase voltage of the DCM Boost Rectifier;
TON(\u03c6) defines a modulation characteristic for an ON time of the booster section, and is a continuous function;
f1(\u03c6) defines a first function comprising a linear characteristic from 0\u2266\u03c6\u2266\u03c03;
f2(\u03c6) defines a second function comprising a non-linear characteristic from \u03c03\u2266\u03c6\u22662\u03c03; and
f3(\u03c6) defines a third function comprising a linear characteristic from 2\u03c03\u2266\u03c6\u2266\u03c0.
17. The apparatus of claim 16, wherein the switchable booster section comprises a two-switch booster section, and wherein the processor is further operable in response to executable instructions for:
modulating the two-switch booster section wherein:
f1(\u03c6) and f3(\u03c6) are each triangular functions having a positive peak at \u03c6 equals \u03c06 and 5\u03c06, respectively; and
f2(\u03c6) is a quadratic function having a minimum at \u03c6=\u03c02.
18. The apparatus of claim 16, wherein the switchable booster section comprises a six-switch booster section, and wherein the processor is further operable in response to executable instructions for:
modulating the six-switch booster section wherein:
f1(\u03c6) is a linear function having a negative slope and a peak at \u03c6=0;
f2(\u03c6) is a quadratic function having a minimum at \u03c6=\u03c02; and
f3(\u03c6) is a linear function having a positive slope and a peak at \u03c6=\u03c0.
19. The apparatus of claim 16, wherein the processor is further operable in response to executable instructions for:
prior to the modulating, defining the modulation signal for a specified DCM Boost Rectifier that satisfies a defined set of cost functions, thereby defining a quasi-optimal modulation signal.
20. The apparatus of claim 19, wherein the processor is further operable in response to executable instructions for:
defining the modulation signal by reference to a look up table, defining the modulation signal by performing a real-time iterative analysis relating to an operational parameter of the DCM Boost Rectifier, or both.