Automotive power system with noise mitigation

Abstract

The present disclosure provides an automotive power system with noise mitigation. In one example, a switched mode power converter includes a transformer having a primary coil and a pair of secondary coils in phase with the primary coil; and a pair of output circuits defining a pair of outputs of opposite polarity. Each of the output circuits includes a rectifier diode having an anode directly connected to the point terminal of one of the secondary coils such that electromagnetic noise generated by the rectifier diode is at least partially cancelled.

Description

Technical Field

[0001] The present disclosure relates to automotive power systems. Background Art

[0002] Automotive power systems can include a variety of electrical subsystems, such as switched-mode power converters. Summary of the Invention

[0003] An automotive power electronics device has a switched-mode power converter that includes: a transformer having a primary coil and a pair of secondary coils in phase with the primary coil; and a pair of output circuits that define a pair of outputs of opposite polarities, each of the output circuits including a rectifier diode having an anode directly connected to a dotted terminal of one of the secondary coils such that electromagnetic noise generated by the rectifier diodes is at least partially cancelled.

[0004] An automotive power electronics device has a switched-mode power converter that includes: a transformer having a primary coil and a pair of secondary coils in phase with the primary coil; and a pair of output circuits that define a pair of outputs of the same polarity, one of the output circuits including a rectifier diode having an anode directly connected to an undotted terminal of one of the secondary coils and the other of the output circuits including a rectifier diode having a cathode directly connected to a dotted terminal of the other of the output circuits such that electromagnetic noise generated by the rectifier diodes is at least partially cancelled.

[0005] An automotive power electronics device has a switched-mode power converter that includes a pair of output circuits, each output circuit having an output and a rectifier diode, the rectifier diodes being arranged such that electromagnetic noise generated by the rectifier diodes is at least partially cancelled. Brief Description of the Drawings

[0006] Figure 1 is a schematic diagram of an automotive power circuit showing noise generation and propagation.

[0007] Figure 2 is a schematic diagram showing noise coupling.

[0008] Figure 3 and Figure 4 is a schematic diagram of a switched-mode power converter having components arranged to facilitate noise cancellation.

[0009] Figure 5 is a graph of switching waveforms and corresponding noise without using the component placement strategy described herein.

[0010] Figure 6 is a graph of the switching waveform and corresponding noise when using the component placement strategy described herein. DETAILED DESCRIPTION

[0011] Embodiments are described herein. However, it should be understood that the disclosed embodiments are merely examples and other embodiments may take different and alternative forms. The drawings are not necessarily to scale. Some features may be enlarged or minimized to show details of particular components. Thus, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching one of ordinary skill in the art.

[0012] The various features shown and described in any one of the reference drawings may be combined with features shown in one or more other drawings to produce embodiments not explicitly shown or described. Combinations of the shown features provide representative embodiments for typical applications. However, for a particular application or implementation, various combinations and modifications of the features may be desirable that are consistent with the teachings of this disclosure.

[0013] This disclosure includes example designs for reducing electromagnetic noise present at certain locations within a circuit. These designs can reduce electromagnetic noise by generating synchronous out-of-phase noise having a matching coupling coefficient, the matching coupling coefficient causing at least partial cancellation of the noise transmitted to a certain location.

[0014] Figure 1 An example of noise generation and propagation within an automotive power system is shown. In other words, Figure 1 the problem alleviated by the content of this disclosure is shown.

[0015] Figure 1 The left portion of shows a flyback converter 70. The flyback converter 70 includes a power supply 10, a switch 20, and a transformer including a primary winding 42 and a secondary winding 44. The rapid operation of the switch 20 generates electromagnetic noise 32. The electromagnetic noise 32 can propagate from the primary winding 42 to the secondary winding 44 to become secondary-side electromagnetic noise 34. The noise 32, 34 is drawn as a decaying sine wave, but the noise 32, 34 can take any waveform.

[0016] The circuit connected to the primary winding 42 can be replaced with different components, and in some cases, the electromagnetic noise 32 can still propagate to become secondary-side electromagnetic noise 34. The circuit connected to the secondary winding 44 can be replaced with different components, and in some cases, the electromagnetic noise 32 can still propagate to become secondary-side electromagnetic noise 34.

[0017] Figure 1The right part shows the DC / AC bus 80. The DC / AC bus 80 is used here as an example of some other subsystems that may not inherently generate electromagnetic noise, such as the electromagnetic noise 32 of the flyback converter 70. Any other subsystem can replace the DC / AC bus 80, and the principles discussed herein can apply.

[0018] Figure 1 Also shown is the parasitic coupling 50 between the flyback converter 70 and the DC / AC bus 80. The directionality of the parasitic coupling 50 only means to indicate that the electromagnetic noise 32 and the secondary-side electromagnetic noise 34 can be transferred from the flyback converter 70 to the DC / AC bus 80 due to the parasitic coupling 50. Finally, Figure 1 it is shown that the electromagnetic noise 32 and the secondary-side electromagnetic noise 34 transferred from the flyback converter 70 to the DC / AC bus 80 can then propagate in the direction 60 to other connected subsystems not shown.

[0019] In summary, Figure 1 it is shown that a first subsystem generating high-frequency electromagnetic noise with fast voltage or current switching transitions may cause noise to propagate through a separate, unconnected but parasitically coupled second subsystem. (This can be generalized to describe noise propagation on n connected or coupled subsystems). Electromagnetic compatibility (EMC) standards may apply to the noise present in the subsystem, so the noise propagating throughout the subsystem may cause the vehicle to fail to meet the EMC standards.

[0020] Figure 2 An example of the generalization of the present disclosure is shown. Consider some noise sources 30 and a sensitive point 101. The noise can travel in the first direction 36 and the second direction 38 throughout the circuit. The noise traveling in the first direction 36 and the noise traveling in the second direction 38 may have different phases. Based on the layout of the circuit including the noise source and the sensitive point, any of the following may occur due to coupling: (a) the noise from the noise source 30 may be undetectable at the sensitive point 101; (b) the noise traveling in the first direction 36 may be detectable at the sensitive point 101 by propagating on the first coupling path 52; (c) the noise traveling in the second direction 38 may be detectable at the sensitive point 101 by propagating on the second coupling path 54; or (d) both noises 36 and 38 may be detectable at the sensitive point 101 by propagating on the first coupling path 52 and the second coupling path 54 respectively. For this discussion, assume (d), and note that the noises 36 and 38 may not be equal.

[0021] According to the present disclosure, a circuit layout can be designed to reduce the detectability of noise generated by a noise source 30 measured at a sensitive point 101. To achieve the reduction, the circuit can be designed such that a first coupling path 52 and a second coupling path 54 cause noise traveling in a first direction 36 and noise traveling in a second direction 38 (possibly having different phases) to at least partially cancel when measured at the sensitive point 101.

[0022] For example, considering that the noise source 30 generates a sine wave, the first coupling path 52 and the second coupling path 54 have the same distance and contain the same medium, and the circuit is symmetric with respect to the sensitive point 101 as depicted in Figure 1 Under these assumptions, no noise should be measured at the sensitive point 101 because the noise from the first coupling path 52 and the noise from the second coupling path 54 should reach the sensitive point 101 with equal amplitudes but opposite phases.

[0023] Figure 2 The example of can be further generalized to a circuit group that includes any number of noise sources 30, any number of sensitive points 101, and any geometry. For any combination of these variables, there are some configurations to optimize some minimization criteria for the noise detectable at the sensitive point 101.

[0024] Figure 3 A circuit showing an embodiment including a noise mitigation design is shown. The circuit includes a power supply 310 connected to a switch 320 and a primary winding 342. The circuit includes a dual secondary winding: a top winding 344 and a bottom winding 346. The top winding 344 and the bottom winding 346 have the same directionality, as indicated by the dots in the figure. The circuit further includes a top rectifier diode 394 directly connected to the top winding 344 and a bottom rectifier diode 392 directly connected to the bottom winding 346. The dotted side of the top winding 344 is directly connected to the anode of the top rectifier diode 394. The dotted side of the bottom winding 346 is directly connected to the anode of the bottom rectifier diode 392.

[0025] Consider the electromagnetic noise generated by the switch 320. In the manner discussed for Figure 1 this electromagnetic noise can be transferred from the primary winding 342 to each of the top winding 344 and the bottom winding 346 and propagate throughout the circuit attached to the top winding 344 and the bottom winding 346. The noise transferred in this way measured at the top rectifier diode 394 and the noise measured at the bottom rectifier diode 392 can have different phases or opposite polarities.

[0026] Figure 3Also shown is that the noise on the top rectifier diode 394 travels along the top coupling 354 to the sensitive point or other points of interest. Similarly, the noise on the bottom rectifier diode 392 is depicted as traveling along the bottom coupling 352 to the sensitive point or other points of interest. Finally, Figure 3 it is shown that through careful circuit design, noise cancellation 399 can occur at the sensitive point or other points of interest. The circuit connected to the primary winding 342, the top winding 344, and the bottom winding 346 can include a switched-mode power converter, a flyback converter, or can be different from that depicted and still there can be noise mitigation. This design concept can be generalized to any number of noise sources or points of interest and any geometry.

[0027] In some embodiments, each of the circuits connected to the top winding 344 and the bottom winding 346 can include a capacitor that shares a node with the rectifier diodes 394, 392 as depicted. In some embodiments, the switch 320 connects the primary winding 342 and the power supply 310 as depicted. In some embodiments, the switch 320 can also be directly connected to the dotted terminal of the primary coil as depicted. In some embodiments, the positive terminal of the power supply 310 is directly connected to the non-dotted terminal of the primary winding 342. In some embodiments, the circuit connected to the primary winding 342 can include a buffer circuit.

[0028] Figure 4 Shown is a circuit of another embodiment that includes a noise mitigation design. The circuit includes a power supply 410 connected to a switch 420 and a primary winding 442. The circuit includes a dual secondary winding: a top winding 444 and a bottom winding 446. The top winding 444 and the bottom winding 446 have the same directionality as indicated by the dots in the figure. The circuit also includes a top rectifier diode 494 directly connected to the top winding 444 and a bottom rectifier diode 492 directly connected to the bottom winding 446. The non-dotted side of the top winding 444 is directly connected to the anode of the top rectifier diode 494. The dotted side of the bottom winding 446 is directly connected to the cathode of the bottom rectifier diode 492.

[0029] Consider the electromagnetic noise generated by the switch 420. In the manner discussed for Figure 1 this electromagnetic noise can be transferred from the primary winding 442 to each of the top winding 444 and the bottom winding 446 and propagate throughout the circuits attached to the top winding 444 and the bottom winding 446. The noise transferred in this way measured at the top rectifier diode 494 and the noise measured at the bottom rectifier diode 492 can have the same phase or polarity.

[0030] Figure 4Also shown is that the noise on the top rectifier diode 494 travels along the top coupling 454 to the sensitive point or other points of interest. Similarly, the noise on the bottom rectifier diode 492 is depicted as traveling along the bottom coupling 452 to the sensitive point or other points of interest. Finally, Figure 4 it is shown that through careful circuit design, noise cancellation 499 can occur at the sensitive point or other points of interest. The circuit connected to the primary winding 442, the top winding 444, and the bottom winding 446 can include a switched-mode power converter, a flyback converter, or can be different from that depicted, and noise mitigation can still exist. This design concept can be generalized to any number of noise sources or points of interest and any geometry.

[0031] In some embodiments, each of the circuits connected to the top winding 444 and the bottom winding 446 can include a capacitor sharing a node with the rectifier diodes 494, 492 as depicted. In some embodiments, the switch 420 connects the primary winding 442 and the power supply 410 as depicted. In some embodiments, the switch 420 can also be directly connected to the non-dotted terminal of the primary coil as depicted. In some embodiments, the positive terminal of the power supply 410 is directly connected to the dotted terminal of the primary winding 442. In some embodiments, the circuit connected to the primary winding 442 can include a buffer circuit.

[0032] Figure 5 The experimental output of a circuit without a noise mitigation design is shown, and Figure 6 the experimental output of a circuit including a noise mitigation design is shown. Specifically, Figure 5 is the original result, and Figure 6 is the result after moving the diode from the positive side of the output to the negative side. Figure 5 is intended to be compared with Figure 6 for comparison.

[0033] Figure 5 includes the MOSFET switch waveform 510 and the measured noise 520. Figure 5 also includes a scale 530. The scale 530 indicates that the MOSFET switch waveform 510 is depicted as 7.0V / div, and the measured noise 520 is depicted as 200.0mV / div. In Figure 5 where the MOSFET switch waveform 510 shows a rapid change in voltage, the measured noise 520 shows the corresponding transient.

[0034] Figure 6 includes the diode switch waveform 610 and the measured noise 620. Figure 6It also includes a scale 630. The scale 630 indicates that the diode switching waveform is depicted as 20.0 V / div, and the measured noise 620 is depicted as 200.0 mV / div. In Figure 6 where the diode switching waveform 610 shows a rapid change in voltage, the measured noise 620 shows the corresponding transient. Figure 6 The transient of the measured noise 620 is less than Figure 5 the transient of the measured noise 520.

[0035] While the foregoing describes exemplary embodiments, these embodiments are not intended to describe all possible forms covered by the claims. The words used in the specification are descriptive rather than restrictive, and it should be understood that various changes may be made without departing from the spirit and scope of the disclosed materials.

[0036] As previously described, the features of the various embodiments may be combined to form additional embodiments that may not be explicitly described or shown in the present disclosure. While the various embodiments may have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art will recognize that one or more features or characteristics may be compromised to achieve the desired overall system attributes, depending on the particular application and implementation. These attributes may include, but are not limited to: strength, durability, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. Thus, embodiments that are described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are within the scope of the present disclosure and may be desirable for a particular application.

[0037] According to the present invention, there is provided an automotive power electronics device having: a switched-mode power converter, the switched-mode power converter including: a transformer having a primary coil and a pair of secondary coils in phase with the primary coil; and a pair of output circuits defining a pair of outputs of opposite polarities, each of the output circuits including a rectifier diode having an anode directly connected to the dotted terminal of one of the secondary coils such that the electromagnetic noise generated by the rectifier diode is at least partially cancelled.

[0038] According to an embodiment, each of the output circuits includes a capacitor having a terminal sharing a node with one of the rectifier diodes.

[0039] According to an embodiment, the switched-mode power converter includes an input power supply and a power switch connected between the primary coil and the input power supply.

[0040] According to an embodiment, the power switch is directly connected to the energized terminal of the primary coil.

[0041] According to an embodiment, the input power supply includes a positive terminal directly connected to the non-energized terminal of the primary coil.

[0042] According to an embodiment, the switched-mode power converter further includes a buffer circuit.

[0043] According to an embodiment, the switched-mode power converter is a flyback switched-mode power converter.

[0044] According to the present invention, there is provided an automotive power electronic device having: a switched-mode power converter including: a transformer having a primary coil and a pair of secondary coils in phase with the primary coil; and a pair of output circuits defining a pair of outputs of the same polarity, one of the output circuits including a rectifier diode having an anode directly connected to the non-energized terminal of one of the secondary coils, and the other of the output circuits including a rectifier diode having a cathode directly connected to the energized terminal of the other of the output circuits, such that electromagnetic noise generated by the rectifier diodes is at least partially cancelled.

[0045] According to an embodiment, each of the output circuits includes a capacitor having a terminal sharing a node with one of the rectifier diodes.

[0046] According to an embodiment, the switched-mode power converter includes an input power supply and a power switch connected between the primary coil and the input power supply.

[0047] According to an embodiment, the power switch is directly connected to the non-energized terminal of the primary coil.

[0048] According to an embodiment, the input power supply includes a positive terminal directly connected to the energized terminal of the primary coil.

[0049] According to an embodiment, the switched-mode power converter further includes a buffer circuit.

[0050] According to an embodiment, the switched-mode power converter is a flyback switched-mode power converter.

[0051] According to the present invention, there is provided an automotive power electronic device having: a switched-mode power converter including a pair of output circuits, each output circuit having an output and a rectifier diode arranged such that electromagnetic noise generated by the rectifier diodes is at least partially cancelled.

[0052] According to an embodiment, the switched-mode power converter includes a transformer having a primary coil and a pair of secondary coils, and wherein an anode of the rectifying diode is directly connected to a dotted terminal of the secondary coil.

[0053] According to an embodiment, the switched-mode power converter includes a transformer having a primary coil and a pair of secondary coils, and wherein a cathode of at least one of the rectifying diodes is directly connected to a dotted terminal of one of the secondary coils.

[0054] According to an embodiment, the outputs have opposite polarities.

[0055] According to an embodiment, the outputs have the same polarity.

Claims

1. An automotive power electronic device, comprising: A switch mode power converter, the switch mode power converter comprising: a transformer having a primary coil and a pair of secondary coils in phase with the primary coil; and a pair of output circuits defining a pair of outputs of opposite polarity, each of the output circuits comprising a rectifier diode having an anode directly connected to a point terminal of one of the secondary coils, so that electromagnetic noise generated by the rectifier diode is at least partially offset. 2 . The automotive power electronic device of claim 1 , wherein each of the output circuits includes a capacitor having a terminal that shares a node with one of the rectifying diodes. 3 . The automotive power electronic device of claim 1 , wherein the switch-mode power converter comprises an input power source and a power switch connected between the primary coil and the input power source. 4 . The automotive power electronic device according to claim 3 , wherein the power switch is directly connected to a live terminal of the primary coil. 5 . The automotive power electronic device of claim 3 , wherein the input power source includes a positive terminal directly connected to a non-charged terminal of the primary coil.

6. The automotive power electronic device of claim 1, wherein the switch-mode power converter further comprises a snubber circuit.

7. The automotive power electronics device of claim 1, wherein the switch-mode power converter is a flyback switch-mode power converter.

8. An automotive power electronic device, comprising: A switch-mode power converter, the switch-mode power converter comprising: a transformer having a primary coil and a pair of secondary coils in phase with the primary coil; and a pair of output circuits, the pair of output circuits defining a pair of outputs of the same polarity, one of the output circuits comprising a rectifier diode having an anode directly connected to a non-charged terminal of one of the secondary coils, and the other of the output circuits comprising a rectifier diode having a cathode directly connected to a charged terminal of the other of the output circuits, so that electromagnetic noise generated by the rectifier diode is at least partially offset. 9 . The automotive power electronic device of claim 8 , wherein each of the output circuits includes a capacitor having a terminal that shares a node with one of the rectifying diodes. 10 . The automotive power electronic device of claim 8 , wherein the switch-mode power converter comprises an input power source and a power switch connected between the primary coil and the input power source. 11 . The automotive power electronic device according to claim 10 , wherein the power switch is directly connected to a non-powered terminal of the primary coil.

12. The automotive power electronic device of claim 10, wherein the input power source includes a positive terminal directly connected to a live terminal of the primary coil.

13. An automotive power electronic device, comprising: A switch mode power converter includes a pair of output circuits, each having an output and a rectifying diode arranged such that electromagnetic noise generated by the rectifying diode is at least partially canceled.

14. The automotive power electronic device of claim 13, wherein the switch-mode power converter comprises a transformer having a primary winding and a pair of secondary windings, and wherein an anode of the rectifier diode is directly connected to a charged terminal of the secondary winding.

15. The automotive power electronic device of claim 13, wherein the switch-mode power converter comprises a transformer having a primary coil and a pair of secondary coils, and wherein a cathode of at least one of the rectifier diodes is directly connected to a charged terminal of one of the secondary coils.

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