Common mode noise suppression of switchmode power converters by capacitive shield with damping network

Patent metadata

Field	Value
Publication number	US-9913356-B2
Application number	US-201415127691-A
Country	US
Kind code	B2
Filing date	Jun 16, 2014
Priority date	Mar 21, 2014
Publication date	Mar 6, 2018
Grant date	Mar 6, 2018

Abstract

A connected light node (CLN) induction light ballast module for powering an induction lamp includes a printed circuit board having components mounted thereon and an earth ground region electrically isolated from a PCB ground region. A heat sink is disposed on a lower layer of the printed circuit board and electrically connected to the earth ground region, wherein a parasitic capacitance occurs between the printed circuit board ground region and the heat sink. A capacitive shield sandwiched by a lower insulating pad and an upper insulating pad is electrically isolated from the heat sink supporting the shield. A damping network electrically connects the capacitive shield to the PCB ground region. Switch-mode power converters are mounted above the upper insulating pad and the shield. The damping network suppresses noise by a parasitic capacitance between the PCB ground region and the heat sink during high frequency power converter operation.

First claim

What is claimed is:

1. An induction light ballast module for powering an induction lamp comprising:
a printed circuit board including an upper layer partitioned into an earth ground region and a printed circuit board ground region, wherein the earth ground region is electrically isolated from the printed circuit board ground region;
a heat sink disposed on an opposing lower layer of the printed circuit board and electrically connected to the earth ground region of the printed circuit board, the heat sink dimensioned to extend beyond at least one outer edge of the printed circuit board, and wherein a parasitic capacitance occurs between the printed circuit board ground region and the heat sink;
an alternating current receiving connector and an EMI filter disposed on the earth ground region of the printed circuit board;
an elongate capacitive shield sandwiched by a lower insulating pad and an upper insulating pad provided on the outwardly opposing faces of the capacitive shield, wherein the capacitive shield and the upper and lower insulating pads are disposed across a length of the heat sink adjacent the at least one edge of the printed circuit board, wherein the capacitive shield is electrically isolated from the heat sink by the lower insulating pad;
a damping network electrically connecting the capacitive shield to the printed circuit board ground region;
a rectifier connected to the EMI filter, wherein the rectifier is disposed on the upper insulating pad adjacent the capacitive shield and electrically isolated from the capacitive shield and the heat sink;
a power factor correction circuit connected to the rectifier and disposed on the printed circuit board ground region, and including switch-mode power conveners disposed on the upper insulating pad adjacent the capacitive shield and electrically isolated from the capacitive shield and the heat sink; and
an output power inverter circuit connected to the switch-mode power converter, the output power inverter circuit being disposed on the printed circuit board ground region and including switch-mode power converters disposed on the upper insulating pad adjacent the capacitive shield and electrically isolated from the capacitive shield and the heat sink,
wherein a parasitic capacitance occurs between the printed circuit board ground region and the heat sink, and wherein the capacitive shield and the damping network provide common mode noise suppression.

2. The induction light ballast module of claim 1 , wherein the output from the output power inverter circuit operates at an RF frequency and the damping network comprises at least one of a resistor and a ferrite that dampens resonance and harmonics to minimize incidental RF broadcast by external cables connected to the induction light ballast module.

3. The induction light ballast module of claim 2 , further comprising:
a zigbee circuit for wireless communication with other devices;
a flyback circuit for providing power supply voltages to the power factor correction circuit, the output power inverter circuit and the zigbee circuit; and
a controller for operating the circuits and for enabling remote wireless control of the induction light ballast module via the zigbee circuit.

4. The induction light ballast module of claim 1 , providing an output power of between approximately 300 watts and approximately 500 watts for driving a lamp.

5. The induction light ballast module of claim 1 , wherein the upper layer and the lower layer comprise two of four layers of the printed circuit board.

6. The induction light ballast module of claim 1 , wherein the rectifier comprises a bridge rectifier, the switch-mode power converters of the power factor correction circuit comprise four switch-mode power converters, and the switch-mode power converters of the output invertor circuit comprise two switch-mode power converters.

7. The induction light ballast module of claim 1 , wherein the damping network and the capacitive shield minimize resonant frequencies incidentally output by the switch-mode power converters.

8. The induction light ballast module of claim 1 , wherein the switch-mode power converters comprise output power diodes and field effect transistors.

9. The induction light ballast module of claim 1 , further comprising thermally conducting fasteners securing the power converters and the printed circuit board to the heat sink, the fasteners enabling thermal conduction from the power converters to the heat sink.

10. The induction light ballast module of claim 9 , further comprising grounding fasteners securing the printed circuit board to the heat sink and electrically connecting the earth ground region of the printed circuit board to the heat sink.

11. The induction light ballast module of claim 1 , wherein the switch-mode power converters of the power factor correction circuit comprise two output power diodes and two power factor correction field effect transistors.

12. The induction light ballast module of claim 1 , further comprising a temperature sensor for sensing temperature and a controller for controlling operation of the induction light ballast module in response to sensed temperature.

13. The induction light ballast module of claim 1 , wherein the induction light ballast module comprises a connected light node induction light ballast module.

14. A connected light node induction light ballast system comprising:
a housing;
a connected light node induction light ballast module disposed in the housing, the connected light node induction light ballast module comprising:
a printed circuit board including an upper layer partitioned into an earth ground region and a printed circuit board ground region, wherein the earth ground region is electrically isolated from the printed circuit board pound region;
a heat sink disposed on an opposing lower layer of the printed circuit board and electrically connected to the earth ground region of the printed circuit board, the heat sink dimensioned to extend beyond at least one outer edge of the printed circuit board, and wherein a parasitic capacitance occurs between the printed circuit board ground region and the heat sink;
an alternating current receiving connector and an EMI filter disposed on the earth ground region of the printed circuit board;
an elongate capacitive shield sandwiched by a lower insulating pad and an upper insulating pad provided on the outwardly opposing faces of the capacitive shield, wherein the capacitive shield and the upper and lower insulating pads are disposed across a length of the heat sink adjacent the at least one edge of the printed circuit board, wherein the capacitive shield is electrically isolated from the heat sink by the lower insulating pad;
a damping network electrically connecting the capacitive shield to the printed circuit board ground region;
a rectifier connected to the EMI filter, wherein the rectifier is disposed on the upper insulating pad adjacent the capacitive shield and electrically isolated from the capacitive shield and the heat sink;
a power factor correction circuit connected to the rectifier and disposed on the printed circuit board ground region, and including switch-mode power converters disposed on the upper insulating pad adjacent the capacitive shield and electrically isolated from the capacitive shield and the heat sink; and
an output power inverter circuit connected to the switch-mode power converter, the output power inverter circuit being disposed on the printed circuit board ground region and including switch-mode power converters disposed on the upper insulating pad adjacent the capacitive shield and electrically isolated fr

Assignees

• Bosch Gmbh Robert

Inventors

• Rostamzadeh Cyrous
• Wang Shijie
• Das Rajesh
• Gladstein Steven
• Foster Timothy
• Marecki Allen
• Master Sanjai

Classifications

• H05B47/19

  via wireless transmission · CPC title

• H02M1/44

  Circuits or arrangements for compensating for electromagnetic interference in converters or inverters · CPC title

• H05B41/24 Primary

  in which the lamp is fed by high frequency AC {, or with separate oscillator frequency} (H05B41/26 takes precedence) · CPC title

• H05B41/2806 Primary

  with semiconductor devices and specially adapted for lamps without electrodes in the vessel, e.g. surface discharge lamps, electrodeless discharge lamps · CPC title

• H02M1/42

  Circuits or arrangements for compensating for or adjusting power factor in converters or inverters · CPC title