EMI Reduced Power Inverter

• US 20070296271A1
• Filed: 06/22/2006
• Published: 12/27/2007
• Est. Priority Date: 06/22/2006
• Status: Active Grant

• Current Assignee: Hitachi Automotive Systems Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Shao, Liang, Funato, Hiroki, Torigoe, Makato, Nakamura, Takayoshi, Saikalis, George
• Granted Patent: US 7,547,987 B2
• Time in Patent Office: Days
• US Class Current: 307/10.1
• CPC Class Codes: B60L 2270/147 electro magnetic [EMI]
• CPC Class Codes: H02M 1/44 Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
• CPC Class Codes: H02M 7/003 Constructional details, e.g. physical layout, assembly, wiring or busbar connections

Abstract

A power inverter of the type used with hybrid electric vehicles having a circuit board with a power layer having a first and second section which are electrically separated using slits from each other on the power layer. A control circuit is connected to and powered by the first section of the power layer while a switching power supply is connected to and powered by the second section of the power layer. An electromagnetic filter is electrically connected between the sections of the power layer. This electromagnetic filter blocks high frequency noises of the type generated by the switching power supply while enabling the sections to be maintained at the same DC voltage level. Optionally, a ferrite covering is provided around a current bus bar of the power inverter to contain magnetic fields generated by current flow through the bus bar.

Claims

1. A power inverter comprising:

a printed circuit board having at least one power layer with at least a first and a second section, said sections being electrically separated from each other on said power layer,

a circuit component connected to and powered by said first section of the power layer,

a switching power supply connected to and powered by said second section of the power layer,

an electromagnetic filter electrically connected between said sections of said power layer, said filter configured to block at least a portion of high frequency signals between said sections while enabling said sections to be maintained at the same DC voltage level.

2. The invention as defined in claim 1 wherein said electromagnetic filter comprises an inductor.

3. The invention as defined in claim 1 wherein said electromagnetic filter comprises a capacitor.

4. The invention as defined in claim 1 wherein said power inverter is used to power a hybrid electric vehicle.

5. The invention as defined in claim 1 wherein said printed circuit board comprises:

a ground layer having a first section and a second section electrically separated from each other on said ground layer,

a load circuit, functioning as control or signal conditioning, etc., connected to said first section of the ground layer,

a PWM switching power supply module connected to said second section of the ground layer,

a second electromagnetic filter electrically connected between said sections of said ground layer, said filter configured to block a portion of high frequency noise from said sections of the ground layer while enabling said sections to be maintained at the same DC voltage level.

6. The invention as defined in claim 5 wherein said second electromagnetic filter comprises an inductor.

7. The invention as defined in claim 5 wherein said second electromagnetic filter comprises a capacitor.

8. The invention as defined in claim 1 wherein the power inverter contains a current bus bar and comprising a ferrite covering around said bus bar.

9. A method for attenuating electromagnetic interference on a printed circuit board of a power inverter between a switching power supply and a circuit component electrically connected to a power layer comprising the steps of:

electrically separating the power layer into a first and second section, said first section connected to the control circuit and said second section connected to the switching power supply,

electrically connecting an electromagnetic filter between the sections of the power layer, said filter being configured to block high frequency signals of the type generated by the switching power supply while enabling the sections to be maintained at the same DC voltage level.

10. The invention as defined in claim 9 wherein said filter comprises an inductor.

11. The invention as defined in claim 9 wherein said filter comprises a capacitor.

12. The invention as defined in claim 9 wherein the printed circuit board includes a ground layer and further comprising the steps of:

electrically separating the ground layer into a first and second section, said first section connected to the control circuit and said second section connected to the switching power supply,

electrically connecting a second electromagnetic filter between the sections of the ground layer, said filter being configured to block high frequency signals of the type generated by the switching power supply while enabling the sections to be maintained at the same DC voltage level.

13. The invention as defined in claim 12 wherein said second electromagnetic filter comprises an inductor.

14. The invention as defined in claim 12 wherein said second electromagnetic filter comprises a capacitor.

15. The invention as defined in claim 9 wherein the power inverter is employed in a hybrid electric vehicle.

16. A power inverter for a hybrid electric vehicle comprising:

a housing,

a power bus contained in said housing,

a ferrite covering disposed around said power bus for the purpose of magnetic field shielding.

17. The invention as defined in claim 16 wherein the ferrite covering is disposed on said power bus.

18. The invention as defined in claim 16 wherein the ferrite covering is disposed on said housing.

19. A method for attenuating electromagnetic interference on a printed circuit board of a power inverter between a switching power supply and other circuit components on a common power plane comprising the steps of:

electrically isolating sections of the power plane containing each switching power supply from other circuit components,

attenuating EMI from those sections of the power plane containing a switching power supply and to the other sections of the power plane by connecting EMI filters between said sections.

20. The invention as defined in claim 19 wherein the EMI filter comprises an inductor.