Methods and devices for input waveform control in switching power supplies

• US 7,382,112 B2
• Filed: 08/16/2005
• Issued: 06/03/2008
• Est. Priority Date: 08/16/2005
• Status: Expired due to Fees

• Current Assignee: Board of Trustees of The University of Illinois
• Original Assignee: Board of Trustees of The University of Illinois
• Inventors: Krein, Philip T.
• Primary Examiner(s): Han; Jessica
• Assistant Examiner(s): Pham; Emily P
• Application Number:
  US11/204,776
• Publication Number:
  US 20070040533A1
• Time in Patent Office: 1,022 Days
• Field of Search: 323/207, 323/210, 363 39- 48
• US Class Current: 323/207
• CPC Class Codes: G05F 1/70 Regulating power factor; Regulating reactive current or power
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

The invention recognizes that filter size can be reduced substantially as power factor is permitted to deviate below unity in systematic ways. Preferred methods of the invention provide specific, computable waveforms that permit use of a minimum filter size given a desired target power factor.

Claims

1. A method for input waveform control of a switching power supply converter device, the method comprising steps of:

accepting time-varying input power;

applying a distorted current waveform to the time-varying input power to introduce a controlled distortion into the time-varying input power, the distorted current waveform introducing, with respect to a fundamental current waveform of the time-varying input power, a limited number of harmonics of respective specific magnitudes or an approximation thereof into the input power to achieve a predetermined non-unity power factor.

2. The method of claim 1, wherein the controlled distortion in the time-varying input power maintains the time-varying input power within a regulatory standard for utility power quality.

3. The method of claim 2, wherein the controlled distortion meets harmonic requirements of IEC 61000-3-2 (class A) for input power levels up to about 900 W.

4. The method of claim 1, wherein the distorted current waveform is determined substantially in accordance with the relationships defined in the following table:

5. The method of claim 4, wherein the distorted current waveform is produced by a digital signal processor.

6. The method of claim 4, wherein the distorted current waveform is produced by a waveform shaping network.

7. The method of claim 1, wherein the limited number of harmonics comprises n harmonics and the respective specific magnitudes of the n harmonics are determined substantially in accordance with a series wherein a 2n−

1 harmonic in the series has an magnitude 1/n, and other harmonics have magnitudes 2/n, 3/n, 4/n, etc. and signs alternate in the series.

8. The method of claim 7, wherein the distorted current waveform is determined substantially in accordance with the relationships defined in the following table:

9. The method of claim 1, the limited number of harmonics comprises n harmonics, i₃ is the magnitude of the third harmonic, and the respective specific magnitudes of the n harmonics are determined substantially in accordance:

10. The method of claim 9, wherein the limited number of n harmonics is determined substantially in accordance with the following table:

11. The method of claim 1, wherein the limited number of harmonics comprises n harmonics and the respective specific magnitudes of the n harmonics are determined substantially in accordance with a series where relative magnitudes of the n harmonics decrease in increments of 1/n and signs alternate in the series.

12. A circuit for producing a correction current waveform for input waveform control of a switching power supply converter device, the circuit comprising:

means for observing an input voltage waveform from a power source;

means for truncating a signal corresponding to the voltage waveform by a truncation amount that targets a specific non-unity power factor to produced a truncated waveform;

means for scaling and subtracting the truncated waveform from the absolute value of the input voltage waveform to produce the correction current waveform.

13. The circuit of claim 12, wherein the means for truncating applies a truncation amount substantially in accordance with the following table: