Adjustable AC/DC conversion topology to regulate an isolated DC load with low AC ripple

Patent metadata

Field	Value
Publication number	US-10947636-B2
Application number	US-201715465110-A
Country	US
Kind code	B2
Filing date	Mar 21, 2017
Priority date	Mar 21, 2017
Publication date	Mar 16, 2021
Grant date	Mar 16, 2021

Abstract

Electroplating and painting systems, methods and power converters are disclosed to provide regulated individual DC output signals to anode structures distributed in a plating solution in a tank to promote formation of plating material on a workpiece using a PWM inverter to generate a first AC signal, a sinewave filter to provide a filtered AC signal, a multiphase isolation transformer to provide a plurality of isolated AC signals, a multi-pulse diode bridge rectifier to provide a DC rectifier output signal, an output filter to provide a filtered DC rectifier output signal, and a blocking diode to provide the filtered DC rectifier output signal to the corresponding tank anode structure.

First claim

The following is claimed:

1. A system to apply a coating to a workpiece, comprising:
a tank at least partially filled with a solution, and extending along a process direction from an entry end to an exit end;
a plurality of tank anode structures mounted in distributed fashion along the process direction between the entry end and the exit end of the tank, the individual anode structures being electrically connected to the solution in the tank;
a plurality of power converter modules individually including a first output to provide a DC output signal to a corresponding one of the tank anode structures, the individual power converter modules including:
an adjustable voltage, adjustable frequency pulse width modulation (PWM) inverter to generate a first AC signal according to a desired fundamental inverter AC output frequency and a voltage reference,
a sinewave filter, including an input to receive the first AC signal, and an output to provide a filtered AC signal,
a multiphase isolation transformer, including a primary winding to receive the filtered AC signal, and a multiphase secondary to provide a plurality of isolated AC signals,
a multi-pulse diode bridge rectifier, including a plurality of rectifier inputs to receive the plurality of isolated AC signals, and a rectifier output to provide a DC rectifier output signal,
an output filter, including an input to receive the DC rectifier output signal, and an output to provide a filtered DC rectifier output signal, and
a blocking diode, including an anode connected to the output of the output filter, and a cathode to provide the filtered DC rectifier output signal to the corresponding tank anode structure to promote formation of material on the workpiece travelling along the process direction between the entry end and the exit end.

2. The system of claim 1 , wherein the PWM inverter regulates the filtered DC rectifier output signal by adjusting the first AC signal at least partially according to a feedback signal from the output filter.

3. The system of claim 1 , wherein the PWM inverter provides the first AC signal at a signal frequency in a range of about 120 Hz to about 600 Hz.

4. The system of claim 3 , wherein the PWM inverter provides the first AC signal at a signal frequency in a range of about 180 Hz to about 300 Hz.

5. The system of claim 3 , wherein the PWM inverter provides the first AC signal at a signal frequency of about 180 Hz.

6. The system of claim 1 , wherein the PWM inverter includes a six pulse inverter switching circuit, including three pairs of upper and lower switching devices individually coupled between a DC bus node and a corresponding one of three output nodes to provide the first AC signal as a three phase AC signal.

7. The system of claim 1 , wherein the plurality of power converter modules operate according to a profile defining setpoints for the individual power converter modules.

8. The system of claim 1 , wherein the multiphase isolation transformer is a six-phase transformer with an electrostatic shield connected to a ground.

9. The system of claim 1 , wherein the multiphase isolation transformer is a nine-phase transformer with an electrostatic shield connected to a ground.

10. The system of claim 1 , further comprising an input rectifier to provide a DC input signal to the PWM inverter.

11. A power converter to provide a DC output signal to an anode structure in an electroplating or painting system, comprising:
an adjustable voltage, adjustable frequency pulse width modulation (PWM) inverter to generate a first AC signal according to a desired fundamental inverter AC output frequency and a voltage reference;
a sinewave filter, including an input to receive the first AC signal, and an output to provide a filtered AC signal;
a multiphase isolation transformer, including a primary winding to receive the filtered AC signal, and a multiphase secondary to provide a plurality of isolated AC signals;
a multi-pulse diode bridge rectifier, including a plurality of rectifier inputs to receive the plurality of isolated AC signals, and a rectifier output to provide a DC rectifier output signal;
an output filter, including an input to receive the DC rectifier output signal, and an output to provide a filtered DC rectifier output signal; and
a blocking diode, including an anode connected to the output of the output filter, and a cathode to provide the filtered DC rectifier output signal to a corresponding tank anode structure to promote formation of material on a workpiece travelling along a process direction between an entry end and an exit end.

12. The power converter of claim 11 , wherein the PWM inverter regulates the filtered DC rectifier output signal by adjusting the first AC signal at least partially according to a feedback signal from the output filter.

13. The power converter of claim 11 , wherein the PWM inverter provides the first AC signal at a signal frequency in a range of about 120 Hz to about 600 Hz.

14. The power converter of claim 13 , wherein the PWM inverter provides the first AC signal at a signal frequency in a range of about 180 Hz to about 300 Hz.

15. The power converter of claim 13 , wherein the PWM inverter provides the first AC signal at a signal frequency of about 180 Hz.

16. The power converter of claim 11 , wherein the PWM inverter includes a six pulse inverter switching circuit, including three pairs of upper and lower switching devices individually coupled between a DC bus node and a corresponding one of three output nodes to provide the first AC signal as a three phase AC signal.

17. The power converter of claim 11 , wherein the multiphase isolation transformer is a six-phase transformer with an electrostatic shield connected to a ground.

18. The power converter of claim 11 , wherein the multiphase isolation transformer is a nine-phase transformer with an electrostatic shield connected to a ground.

19. The power converter of claim 11 , further comprising an input rectifier to provide a DC input signal to the PWM inverter.

20. A method to apply a coating to a workpiece, comprising:
moving a workpiece through a solution in a tank along a process direction between an entry end and an exit end;
providing a DC voltage signal to each of a plurality of tank anode structures distributed in the solution along the process direction between the entry end and the exit end of the tank to promote formation of material on the workpiece; and
generating the individual DC voltage signals according to a profile defining setpoints for the individual power converter modules, including for each tank anode structure:
generating a first AC signal at a frequency in a range of about 120 Hz to about 600 Hz using an adjustable voltage, adjustable frequency pulse width modulation (PWM) inverter according to a desired fundamental inverter AC output frequency and a voltage reference,
filtering the first AC signal to generate a filtered AC signal using a sinewave filter,
generating a plurality of isolated AC signals according to the filtered AC signal using a multiphase isolation transformer,
rectifying the isolated AC signals to generate a DC rectifier output signal using a multi-pulse diode bridge rectifier,
filtering the DC rectifier output signal to generate a filtered DC rectifier output signal using an output filter, and
providing the filtered DC rectifier output to the tank anode structure through a blocking diode.

Assignees

• Rockwell Automation Tech Inc

Inventors

• Guskov Nickolay N
• Skibinski Gary L
• Liu Zhijun
• Sarver William Jonn

Classifications

• H02M1/14 Primary

  Arrangements for reducing ripples from DC input or output · CPC title

• H02M1/348

  Passive dissipative snubbers · CPC title

• H02M1/007

  Plural converter units in cascade (push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826) · CPC title

• H02M3/335

  using semiconductor devices only · CPC title

• C25D17/00 Primary

  Constructional parts, or assemblies thereof, of cells for electrolytic coating · CPC title