METHOD FOR OPERATING A CIRCUIT DEVICE

Abstract

A switching converter, including an input interface for providing an input voltage, an output interface for providing at least one output voltage, a voltage conversion device for converting the provided input voltage into one of the at least one output voltage, and a clock generator for providing a working clock, the clock generator being configured in such a way that the clock generator provides a modulated basic clock as the working clock. A control unit including such a switching converter, and a method for operating such a switching converter, are also described.

Claims

1-10. (canceled)

11. A switching converter, comprising: an input interface for providing an input voltage; an output interface for providing at least one output voltage; a voltage conversion device for converting the provided input voltage into one of the at least one output voltage; and a clock generator for providing a working clock, the clock generator being configured in such a way that the clock generator provides a modulated basic clock as the working clock.

12. The switching converter as recited in claim 11, wherein the clock generator modulates the basic clock at a predetermined frequency deviation and at least one predetermined modulation frequency and at least one predetermined modulation period duration.

13. The switching converter as recited in claim 12, wherein the at least one predetermined modulation frequency includes multiple modulation frequencies, the multiple modulation frequencies being equidistant with respect to one another.

14. The switching converter as recited in claim 12, wherein the at least one predetermined modulation frequency includes multiple modulation frequencies, the multiple modulation frequencies having a logarithmic separation from one another.

15. The switching converter as recited in claim 13, wherein the modulation period duration is between 5 ms and 15 ms.

16. The switching converter as recited in claim 13, wherein the modulation period duration is between 10 ms and 11.1 ms.

17. The switching converter as recited in claim 12, wherein the at least one modulation frequency is/are between 10 kHz and 20 kHz.

18. The switching converter as recited in claim 12, wherein the at least one modulation frequency is/are between 16 kHz and 18 kHz.

19. The switching converter as recited in claim 12, wherein the frequency deviation is less than 15% of the basic clock.

20. The switching converter as recited in claim 12, wherein the frequency deviation is less than 10% of the basic clock.

21. The switching converter as recited in claim 12, wherein the frequency deviation is 9% of the basic clock.

22. A control unit for a motor vehicle, preferably for activating passenger protection device, the control unit including at least one switching converter, the at least one switching converter including an input interface for providing an input voltage, an output interface for providing at least one output voltage, a voltage conversion device for converting the provided input voltage into one of the at least one output voltage, and a clock generator for providing a working clock, the clock generator being configured in such a way that the clock generator provides a modulated basic clock as the working clock.

23. A method for operating a switching converter including a clock generator, the method comprising: providing a working clock for the switching converter, the working clock being provided as a modulated basic clock.

24. The method as recited in claim 23, wherein the basic clock is modulated at a predetermined frequency deviation and at least one predetermined modulation frequency and at least one predetermined modulation period duration.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] FIG. 1 shows a schematic view of a switching converter according to the present invention.

[0048] FIG. 2 shows a spectral representation of an exemplary frequency modulation.

[0049] FIG. 3 shows an emission spectrum of a switching converter from the related art.

[0050] FIG. 4 shows an emission spectrum of a switching converter according to the present invention.

[0051] FIG. 5 shows a spectral representation of a frequency modulation and a resulting measuring signal.

[0052] FIG. 6 shows the emission spectrum of a switching converter according to the present invention having a basic clock of 1.8725 MHz and a frequency deviation of 9%.

[0053] FIG. 7 shows an emission spectrum of a switching converter from the related art.

[0054] FIG. 8 shows an emission spectrum of a switching converter according to the present invention.

[0055] FIG. 9 shows a flow chart of the method according to the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0056] In the description below of favorable exemplary embodiments of the present invention, identical or similar reference numerals are used for similarly acting elements shown in the different figures, and a repeated description of these elements is dispensed with.

[0057] FIG. 1 shows a schematic view of a switching converter 1 according to the present invention. Switching converter 1 includes an input interface 10 for providing an input voltage V.sub.in, an output interface 11 for providing at least one output voltage V.sub.out, and a voltage conversion device 12 for converting the provided input voltage V.sub.in into one of the at least one output voltage [sic] V.sub.out. Furthermore, switching converter 1 according to the present invention includes a clock generator 13, which provides a modulated basic clock Clk.sub.base as working clock Clk.sub.modulated.

[0058] FIG. 2 shows a spectral representation of an exemplary frequency modulation. The settings for the shown frequency modulation FM are as follows:

[0059] Carrier frequency f.sub.T: 100 MHz

[0060] Frequency deviation Δf.sub.T: 100 kHz

[0061] Modulation frequency f.sub.S: 1 kHz

[0062] The spectra shown “to the left and right” of the carrier are the upper and lower sidebands.

[0063] FIG. 3 shows an emission spectrum of a switching converter from the related art having a working frequency of 1.87525 MHz.

[0064] The spectrum of interference of a switching converter is defined by its rectangular activation of the converter choke. This rectangle is spectrally made up of many harmonic sinusoidal oscillations, which are each an integer multiple of the base frequency (1, 2, 3, 4, 5, . . . ). The amplitudes of the spectrum are dependent on the load situation of the switching converter. Furthermore, the amplitude ratio of the harmonics among one another is dependent on the pulse/pause ratio of the rectangular activation of the converter choke. The solid curve represents the spectrum according to an average detector (AVG), and the thick, dotted curve represents the spectrum according to a peak detector (PK).

[0065] FIG. 4 includes two graphs, which show the emission spectra of a switching converter 1 according to the present invention having a basic clock rate Clk.sub.base (base frequency/1st harmonic) of 2 MHz. The signal is made up of carrier frequency f.sub.T of 2 MHz and 7 superimposed upper and lower sidebands, which are defined by signal frequencies f.sub.s.sub._.sub.sweep (16.2 kHz; 16.5 kHz; 16.8 kHz; 17.1 kHz; 17.4 kHz; 17.7 kHz; 18.0 kHz). The top graph represents the spectrum according to a peak detector (PK). The bottom graph represents the spectrum according to an average detector (AVG).

[0066] FIG. 5 shows a spectral representation of a frequency modulation FM and a resulting measuring signal. The fact that the individual frequencies of the sidebands are not “visible” is due to the used measuring bandwidth (RBW) of 9 kHz and the measuring duration of 1 s. This means that it is not possible to metrologically resolve the individual spectral lines.

[0067] Furthermore, the individual frequency lines (sinusoidal signals) have different phase positions with respect to one another. This is defined by the different phase velocity (frequency). The amplitude of the resulting measuring signal is a sum of the individual amplitudes of the frequency lines. These may add up to or subtract from one another due to the superimposition.

[0068] FIG. 6 shows the emission spectrum of a switching converter 1 according to the present invention having a basic clock Clk.sub.base of 1.8725 MHz and a frequency deviation Δf.sub.T of 9%. During a broader spectral analysis of the emissions of the switching converter, the effects of the modulation of basic clock Clk.sub.base according to the present invention are also apparent in the harmonics.

[0069] As already shown in FIGS. 3 and 4, the emission spectrum in FIG. 6 is also represented based on the thick, dotted curve according to a peak detector (PK) and based on the solid curve according to an average detector (AVG).

[0070] Another effect which becomes apparent starting at approximately 10 MHz is that the sidebands of the harmonics converge. This may be explained by the fact that the frequency deviation Δf.sub.T of 9%, for example, at the basic frequency Clk.sub.base also affects the harmonics.

[0071] Example: At a basic frequency Clk.sub.base of 2 MHz and a frequency deviation Δf.sub.T of 9%, a sideband corresponds to 180 kHz (“to the left or right” of the carrier), and at the 9.sup.th harmonic (10th harmonic) of 2 MHz (20 MHz), a sideband of 1.8 MHz arises. This means that the upper sideband of the 10th harmonic and the lower sideband of the 11th harmonic overlap.

[0072] The resulting effect is particularly apparent in a comparison of the spectra in FIGS. 7 and 8. FIG. 7 shows the emission spectrum of a switching converter from the related art. FIG. 8 shows the emission spectrum of a switching converter 1 according to the present invention. Both switching converters are operated at the same basic clock Clk.sub.base. However, the switching converter according to the present invention is operated at a frequency deviation Δf.sub.T. The switching converter from the related art is operated without frequency deviation.

[0073] As already shown in FIGS. 3, 4 and 6, the emission spectrum in FIG. 6 is also represented based on the thick, dotted curve according to a peak detector (PK) and based on the solid curve according to an average detector (AVG).

[0074] A harmonic at approximately 100 MHz has a sideband of 9 MHz at a deviation of 9%. This means that in this frequency range an overlap of approximately 5 sidebands is present at a frequency point. For a measuring window (common here) of 120 kHz, this yields 33 individual frequency lines (sidebands×RBW/f.sub.Smax->5×120 kHz/18 kHz), which then generate a measuring signal/measuring level in keeping with their amplitude and phase position. The ultimately indicated level is still dependent on the detectors used (AVG, PK), the modulation frequencies f.sub.s.sub._.sub.sweep, and the measuring duration.

[0075] FIG. 9 shows the method according to the present invention for a switching converter 1 including a clock generator 13, which provides a working clock Clk.sub.modulated for switching converter 1. In step 900, working clock Clk.sub.modulated is provided as a modulated basic clock Clk.sub.base.