AC/DC converter and method of modulation thereof

• US 7,375,989 B2
• Filed: 09/28/2005
• Issued: 05/20/2008
• Est. Priority Date: 01/27/2005
• Status: Active Grant

• Current Assignee: ABB Schweiz AG (ABB Limited)
• Original Assignee: General Electric Company
• Inventors: Borgeaud, Nicolas, Kalken, Chris Van, Colombi, Silvio
• Primary Examiner(s): Vu; Bao Q.
• Application Number:
  US11/237,422
• Publication Number:
  US 20060164873A1
• Time in Patent Office: 965 Days
• Field of Search: 363/44, 363/45, 363/84, 363/89, 363/125, 363/127
• US Class Current: 363/44
• CPC Class Codes: H02M 1/12 Arrangements for reducing harmonics from ac input or output
• CPC Class Codes: H02M 1/14 Arrangements for reducing ripples from dc input or output

Abstract

A method and apparatus for modulating a discontinuous conduction mode (DCM) Boost Rectifier having a switchable booster section is disclosed. A modulation signal is defined according to the equation, T_ON(φ)=f1(φ)+f2(φ)+f3(φ). Here, φ defines a phase angle for an input phase voltage of the DCM Boost Rectifier; T_ON(φ) defines a modulation characteristic for an ON time of the booster section, and is a continuous function; f1(φ) defines a first function from 0≦φ≦π/3; f2(φ) defines a second function from π/3≦φ≦2π/3; and, f3(φ) defines a third function from 2π/3≦φ≦π. The switchable booster section is then modulated using the modulation signal.

Claims

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;

T_ON(φ

)=f1(φ

)+f2(φ

)+f3(φ

),

where,

φ

defines a phase angle for an input phase voltage of the DCM Boost Rectifier;

T_ON(φ

) defines a modulation characteristic for an ON time of the booster section, and is a continuous function;

f1(φ

) defines a first function from 0≦

φ

≦

π

/3;

f2(φ

) defines a second function from π

/3≦

φ

≦

2π

/3;

f3(φ

) defines a third function from 2π

/3≦

φ

≦

π

; and

modulating the switchable booster section using the modulation signal.

2. The method of claim 1, wherein:

the f1(φ

) function comprises a linear characteristic;

the f2(φ

) function comprises a non-linear characteristic; and

the f3(φ

) function comprises a linear characteristic.

3. The method of claim 1, wherein:

f1(φ

) and f3(φ

) are each triangular functions having a positive peak at φ

equals π

/6 and 5π

/6, respectively.

4. The method of claim 1, wherein:

f1(φ

) is a linear function having a negative slope and a peak at φ

=0; and

f3(φ

) is a linear function having a positive slope and a peak at φ

=π

.

5. The method of claim 1, wherein:

f2(φ

) is a quadratic function having a minimum at φ

=π

/2.

6. The method of claim 1, wherein:

T_ON(φ

) is defined by;

T_ON(φ

)=K*[Vdc(φ

)−

Vmax(φ

)]^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 T_ON, as a function of the angle φ

, is composed of two triangular portions each having a maximum amplitude defined by coefficient G_p, and by a third harmonic portion having a minimum value defined by coefficient K_T, the K_T minimum being intermediate the two G_p maximums.

8. The method of claim 7, wherein:

the two triangular portions are defined at phase voltage angles 0≦

φ

≦

π

/3 and 2π

/3≦

φ

≦

π

, respectively; and

the third harmonic portion is defined at phase voltage angles π

/3≦

φ

≦

2π

/3.

9. The method of claim 6, wherein:

the modulation characteristic shape of T_ON, as a function of the angle φ

, is composed of two straight line portions each having a maximum amplitude defined by coefficient G_p, and by a third harmonic portion having a minimum value defined by coefficient K_T, the K_T minimum being intermediate the two G_p maximums.

10. The method of claim 9, wherein:

the two straight line portions are defined at phase voltage angles 0≦

φ

≦

π

/3 and 2π

/3≦

φ

≦

π

, respectively; and

the third harmonic portion is defined at phase voltage angles π

/3≦

φ

≦

2π

/3.

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;

T_ON(φ

)=f1(φ

)+f2(φ

)+f3(φ

),

where,

φ

defines a phase angle for an input phase voltage of the DCM Boost Rectifier;

T_ON(φ

) defines a modulation characteristic for an ON time of the booster section, and is a continuous function;

f1(φ

) defines a first function comprising a linear characteristic from 0≦

φ

≦

π

/3;

f2(φ

) defines a second function comprising a non-linear characteristic from π

/3≦

φ

≦

2π

/3; and

f3(φ

) defines a third function comprising a linear characteristic from 2π

/3≦

φ

≦

π

.

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(φ

) and f3(φ

) are each triangular functions having a positive peak at φ

equals π

/6 and 5π

/6, respectively; and

f2(φ

) is a quadratic function having a minimum at φ

=π

/2.

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(φ

) is a linear function having a negative slope and a peak at φ

=0;

f2(φ

) is a quadratic function having a minimum at φ

=π

/2; and

f3(φ

) is a linear function having a positive slope and a peak at φ

=π

.

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.