Method for controlling a double-resonance generator

• US 6,711,533 B1
• Filed: 02/14/2000
• Issued: 03/23/2004
• Est. Priority Date: 02/19/1999
• Status: Expired due to Fees

• Current Assignee: GE Medical Systems Norway AS (General Electric Company)
• Original Assignee: GE Medical Systems Norway AS (General Electric Company)
• Inventors: Boichot, Jérôme, Godoy, Emmanuel, Aymard, Nicolas
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): FERRIS III, FRED O
• Application Number:
  US09/503,026
• Time in Patent Office: 1,499 Days
• Field of Search: 703/13, 703/18, 703/19, 363/17
• US Class Current: 703/13
• CPC Class Codes: H02M 3/3376 with automatic control of output voltage or current

Abstract

The delay time control entails a static term and a corrective term and a current sampling time, the control calculated at the preceding sampling time is applied and the control intended to be applied at the following sampling time is determined. The determination of the following control is made from the working point of the generator, estimated at the following time.

Claims

1. A method of controlling a double-resonance generator delivering a direct-current output voltage supplying a load, in which an output current circulates, involving a delay time control of the transistors of the thyratron inverter of the generator, wherein the control involves a static term and a corrective term, a first table is elaborated, containing for predetermined couples of output voltage and output current values the corresponding values for the static term, and a second table containing corresponding desired values for a first voltage at the terminals of the resonant circuit capacitor and for the current crossing the inductance coil connected in parallel on the capacitor, as well as corresponding gain values a current sampling time the control calculated at the preceding sampling time is applied, and the control intended to be applied at the following sampling time is determined, the static term of the following control is determined from the first table and from the voltage and output current values estimated at the following sampling time, and the corrective term of the following control is determined from the second table, from the values determined at the current sampling time, from the output voltage and output current, from the first voltage and from the said inductance current, as well as from the value of the corrective term calculated at the preceding sampling time.

2. The method according to claim 1, wherein the voltage and output current values are estimated at the following sampling time from a predetermined evolution of a desired output voltage;

and the determination of the corrective term of the following control involves measurement of the current value of the output voltage, of the current value of the first voltage and of the current value of the inductance current, and calculation of the sum of the products of the respective differences between those measured current values and the corresponding desired values by the associated gains, plus the product of the preceding corrective term by the associated gain.

3. The method according to claim 2, wherein the determination of the corrective term of the following control further entails addition of the product of an integral corrective element relative to the output voltage by the associated gain.

4. The method according to claim 1, wherein the elaboration of the first table as well as the elaboration of the desired values for the first voltage and inductance current is obtained by simulation from a generator representation circuit, in which simulation of the desired values are obtained in steady state by using only one transistor of the thyratron inverter and by inverting, at the beginning of each cycle, the variables belonging to the common part of said circuit, and that elaboration of the gains entails the elaboration of a dynamic model, the coefficients of which are obtained by variations of the initial conditions.

5. The method according to claim 2, wherein the elaboration of the first table as well as the elaboration of the desired values for the first voltage and inductance current is obtained by simulation from a generator representation circuit, in which simulation of the desired values are obtained in steady state by using only one transistor of the thyratron inverter and by inverting, at the beginning of each cycle, the variables belonging to the common part of said circuit, and that elaboration of the gains entails the elaboration of a dynamic model, the coefficients of which are obtained by variations of the initial conditions.

6. The method according to claim 3, wherein the elaboration of the first table as well as the elaboration of the desired values for the first voltage and inductance current is obtained by simulation from a generator representation circuit, in which simulation of the desired values are obtained in steady state by using only one transistor of the thyratron inverter and by inverting, at the beginning of each cycle, the variables belonging to the common part of said circuit, and that elaboration of the gains entails the elaboration of a dynamic model, the coefficients of which are obtained by variations of the initial conditions.