Voltage step-up autotransformer, and AC-to-DC converter comprising such an autotransformer
A voltage step-up autotransformer topology and an AC-to-DC converter including such an autotransformer are provided. The autotransformer is configured to take, at input, a three-phase AC current (for example 115 VAC with a constant frequency), and to output nine output voltages, which are supplied to an 18-pulse rectifier bridge assembly so as to supply a high DC voltage (for example +270 VDC/−270 VDC). These are particularly suitable for AC-to-DC converters in the aeronautical sector.
1. A voltage step-up autotransformer, having a magnetic core formed of a first, of a second and of a third limb, said autotransformer being intended to be connected to a three-phase power supply with a given amplitude supplied to a first, to a second and to a third input point and supplying at least three output voltages of a first group of three output voltages in phase with the three-phase power supply and having a given amplitude,
the autotransformer comprising:
a first main winding situated on the first limb between the first and the second input point,
a second main winding situated on the second limb between the second and the third input point,
a third main winding situated on the third limb between the third and the first input point,
the first, the second and the third input points being connected electrically to one another in a triangle assembly,
wherein the autotransformer furthermore comprises:
a first additional winding coupled magnetically to the third main winding and delimited by a first additional terminal where a first voltage of the first group of three output voltages is delivered, the first additional winding being connected to the first input point by way of a first intermediate winding situated on the first limb, the first additional winding and the first intermediate winding being connected to one another by a first terminal,
a second additional winding coupled magnetically to the first main winding and delimited by a second additional terminal where a second voltage of the first group of three output voltages is delivered, the second additional winding being connected to the second input point by way of a second intermediate winding situated on the second limb, the second additional winding and the second intermediate winding being connected to one another by a second terminal,
a third additional winding coupled magnetically to the second main winding and delimited by a third additional terminal where a third voltage of the first group of three output voltages is delivered, the third additional winding being connected to the third input point by way of a third intermediate winding situated on the third limb, the third additional winding and the third intermediate winding being connected to one another by a third terminal.
2. A voltage step-up autotransformer, having a magnetic core formed of a first, of a second and of a third limb, said autotransformer being intended to be connected to a three-phase power supply with a given amplitude supplied to a first, to a second and to a third input point and supplying at least three output voltages of a first group of three output voltages in phase with the three-phase power supply and having a given amplitude,
the autotransformer comprising:
a first main winding situated on the first limb between the first and the second input point,
a second main winding situated on the second limb between the second and the third input point,
a third main winding situated on the third limb between the third and the first input point,
the first, the second and the third input points being connected electrically to one another in a triangle assembly,
wherein the autotransformer furthermore comprises:
a first additional winding coupled magnetically to the first main winding and delimited by a first additional terminal where a first voltage of the first group of three output voltages is delivered, the first additional winding being connected to the first input point by way of a first intermediate winding situated on the third limb, the first additional winding and the first intermediate winding being connected to one another by a first terminal,
a second additional winding coupled magnetically to the second main winding and delimited by a second additional terminal where a second voltage of the first group of three output voltages is delivered, the second additional winding being connected to the second input point by way of a second intermediate winding situated on the first limb, the second additional winding and the second intermediate winding being connected to one another by a second terminal,
a third additional winding coupled magnetically to the third main winding and delimited by a third additional terminal where a third voltage of the first group of three output voltages is delivered, the third additional winding being connected to the third input point by way of a third intermediate winding situated on the second limb, the third additional winding and the third intermediate winding being connected to one another by a third terminal.
3. The autotransformer according to claim 1 , furthermore supplying three output voltages of a second group of three output voltages and three output voltages of a third group of three output voltages and having a desired maximum amplitude different from the desired maximum amplitude of the three output voltages of the first group of three output voltages, the autotransformer comprising:
a first auxiliary winding coupled magnetically to the second main winding, the first auxiliary winding being delimited by the terminal where the first voltage of the second group of three output voltages is delivered and by the terminal where the first voltage of the third group of three output voltages is delivered, the first auxiliary winding being connected to the first intermediate winding at a first intermediate point separate from the first input point,
a second auxiliary winding coupled magnetically to the third main winding, the second auxiliary winding being delimited by the terminal where the second voltage of the second group of three output voltages is delivered and by the terminal of the second voltage of the third group of three output voltages, the second auxiliary winding being connected to the second intermediate winding at a second intermediate point separate from the second input point,
a third auxiliary winding coupled magnetically to the first main winding, the third auxiliary winding being delimited by the terminal where the third voltage of the second group of three output voltages is delivered and by the terminal of the third voltage of the third group of three output voltages, the third auxiliary winding being connected to the third intermediate winding at a third intermediate point separate from the third input point.
4. The autotransformer according to claim 1 , furthermore supplying three output voltages of a second group of three output voltages and three output voltages of a third group of three output voltages and having a desired maximum amplitude identical to the desired maximum amplitude of the three output voltages of the first group of three output voltages, the autotransformer comprising:
two first additional windings coupled magnetically to the first main winding and to the third main winding, respectively, delimited by the terminal where the first voltage of the second group of three output voltages is delivered and by the terminal where the first voltage of the third group of three output voltages is delivered, respectively, and connected to the first input point by way of a first auxiliary winding coupled magnetically to the second main winding,
two second additional windings coupled magnetically to the second main winding and to the first main winding, respectively, delimited by the terminal where the second voltage of the second group of three output voltages is delivered and by the terminal where the second voltage of the third group of three output voltages is delivered, respectively, and connected to the second input point by way of a second auxiliary winding coupled magnetically to the third main winding,
two third additional windings coupled magnetically to the third main winding and to the second main winding, respectively, delimited by the terminal where the third voltage of the second group of three output voltages is delivered and by the terminal where the third voltage of the third group of three output voltages is delivered, respectively, and connected to the third input point by way of a third auxiliary winding coupled magnetically to the first main winding.
5. The autotransformer according to claim 1 , furthermore supplying three output voltages of a second group of three output voltages and three output voltages of a third group of three output voltages and having a desired maximum amplitude lower than the desired maximum amplitude of the three output voltages of the first group of three output voltages, the autotransformer comprising:
a first auxiliary winding coupled magnetically to the second main winding, the first auxiliary winding being delimited by the terminal where the first voltage of the second group of three output voltages is delivered and by the terminal where the first voltage of the third group of three output voltages is delivered, the first auxiliary winding being connected to the first intermediate winding at the first input point,
a second auxiliary winding coupled magnetically to the third main winding, the second auxiliary winding being delimited by the terminal where the second voltage of the second group of three output voltages is delivered and by the terminal of the second voltage of the third group of three output voltages, the second auxiliary winding being connected to the second intermediate winding at the second input point,
a third auxiliary winding coupled magnetically to the first main winding, the third auxiliary winding being delimited by the terminal where the third voltage of the second group of three output voltages is delivered and by the terminal of the third voltage of the third group of three output voltages, the third auxiliary winding being connected to the third intermediate winding at the third input point.
6. The autotransformer according to claim 1 , furthermore supplying three output voltages of a second group of three output voltages and three output voltages of a third group of three output voltages and having a desired maximum amplitude lower than the desired maximum amplitude of the three output voltages of the first group of three output voltages, the autotransformer comprising:
two first additional windings coupled magnetically to the first main winding and to the third main winding, respectively, delimited by the terminal where the first voltage of the second group of three output voltages is delivered and by the terminal where the first voltage of the third group of three output voltages is delivered, respectively, and connected to the first input point by way of a first auxiliary winding coupled magnetically to the second main winding,
two second additional windings coupled magnetically to the second main winding and to the first main winding, respectively, delimited by the terminal where the second voltage of the second group of three output voltages is delivered and by the terminal where the second voltage of the third group of three output voltages is delivered, respectively, and connected to the second input point by way of a second auxiliary winding coupled magnetically to the third main winding,
two third additional windings coupled magnetically to the third main winding and to the second main winding, respectively, delimited by the terminal where the third voltage of the second group of three output voltages is delivered and by the terminal where the third voltage of the third group of three output voltages is delivered, respectively, and connected to the third input point by way of a third auxiliary winding coupled magnetically to the first main winding.
7. The autotransformer according to claim 3 , the first, second and third output voltages of the second group of three output voltages being phase-offset by a first phase offset angle (α), respectively, with respect to the first, second and third output voltages of the first group of three output voltages, and the first, second and third output voltages of the third group of three output voltages being phase-offset by a second phase offset angle, respectively, with respect to the first, second and third output voltages of the first group of three output voltages, the first phase offset angle and the second phase offset angle having the same absolute value (α), the first phase offset angle being positive and the second phase offset angle being negative.
8. The autotransformer according to claim 1 , the phase offset angle (α) being equal to 37°.
9. The autotransformer according to claim 7 , the phase offset angle (α) being equal to 40°.
10. An AC-to-DC converter, wherein it uses an autotransformer according to claim 1 , a forward-biased diode being linked between each output of the autotransformer and a positive output of the converter, and a reverse-biased diode being linked between each output of the autotransformer and a negative output of the converter.