Power factor correction algorithm for arbitrary input waveform

• US 9,000,736 B2
• Filed: 05/03/2013
• Issued: 04/07/2015
• Est. Priority Date: 05/03/2013
• Status: Active Grant

• Current Assignee: Eaton Intelligent Power Limited (Eaton Corporation PLC.)
• Original Assignee: Cooper Technologies Company (Eaton Corporation PLC.)
• Inventors: Gumaer, Traver
• Primary Examiner(s): BERHANE, ADOLF D
• Application Number:
  US13/887,210
• Publication Number:
  US 20140327411A1
• Time in Patent Office: 704 Days
• Field of Search: 323/205, 323/207, 323/222, 323/282, 323/283, 323/285
• US Class Current: 323/222
• CPC Class Codes: B64F 1/205 arranged underground, e.g. underground runway lighting units
• CPC Class Codes: H02M 1/42 Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

The present disclosure provides techniques for a power factor correction system having an arbitrary input waveform. The present disclosure provides two example methods of digital power factor correction that allow for a high power factor on an arbitrary input waveform. The two example methods are applicable to both constant-current inputs and constant-voltage inputs. One example method samples the arbitrary input waveform to produce a reference table used to synchronize the input voltage with the input current in a constant current system, and to synchronize the input current to the input voltage in a constant voltage system. A second example method uses instantaneous input values as a reference in performing power factor correction.

Claims

1. A power factor correction (PFC) circuit for arbitrary input waveforms, comprising:

a controller configured to receive an output signal from a PFC circuit and a reference signal, wherein the controller compares the output signal and the reference signal and produces a feedback output, wherein the controller generates an input reference data derived from an input source and multiplies the input reference data by the feedback output to produce a control signal, wherein the input source is an arbitrary periodic waveform, and wherein the control signal controls and synchronizes an input signal to be in phase with the input source.

2. The power factor correction (PFC) circuit for arbitrary input waveforms of claim 1, wherein the input signal is an input voltage, and the input source is a constant input current.

3. The power factor correction (PFC) circuit for arbitrary input waveforms of claim 1, wherein the input signal is an input current and the input source in a constant input voltage.

4. The power factor correction (PFC) circuit for arbitrary input waveforms of claim 2, further comprising:

a charge capacitor configured to receive the input current from a constant current source and produce the input voltage;

a switching device coupled to the input capacitor, wherein the switching device is switchable between an OFF state and an ON state, wherein the input voltage rises when the switching device is in the OFF state and drains when the switching device is in the ON state; and

wherein the controller synchronizes the input voltage to be in phase with the input current by controlling switching of the switching device.

5. The power factor correction (PFC) circuit for arbitrary input waveforms of claim 1, wherein the input reference comprises a set of digital values sampled from the input source at set intervals over at least a full cycle.

6. The power factor correction (PFC) circuit for arbitrary input waveforms of claim 1, wherein the digital values are normalized values.

7. The power factor correction (PFC) circuit for arbitrary input waveforms of claim 1, wherein the input reference is an instantaneous value of the input source normalized with a cycle maximum.

8. A table method of controlling a power factor correction (PFC) circuit with arbitrary input waveforms, comprising:

sampling an input source at fixed intervals and storing the sampled values;

dividing each sampled value by a cycle minimum to obtain a set of normalized values;

generating an input reference from the set of normalized values;

multiply the input reference by a feedback controller output to obtain a control signal; and

controlling a PFC circuit with the control signal, wherein the PFC circuit produces an input signal synchronized with the input source.

9. The table method of controlling a power factor correction (PFC) circuit with arbitrary input waveforms of claim 8, further comprising:

regulating an output signal of the PFC circuit with an initial fixed duty cycle.

10. The table method of controlling a power factor correction (PFC) circuit with arbitrary input waveforms of claim 8, further comprising:

converting the control signal to a pulse width modulation (PWM) signal; and

controlling the PFC circuit with the PWM signal.

11. The table method of controlling a power factor correction (PFC) circuit with arbitrary input waveforms of claim 8, wherein the input source is a constant input current and the input signal is an input voltage.

12. The table method of controlling a power factor correction (PFC) circuit with arbitrary input waveforms of claim 8, wherein the input source is a constant input voltage and the input signal is an input current.

13. The table method of controlling a power factor correction (PFC) circuit with arbitrary input waveforms of claim 8, further comprising:

sampling an input source at fixed intervals over a full cycle.

14. The table method of controlling a power factor correction (PFC) circuit with arbitrary input waveforms of claim 8, further comprising:

switching a switching device between an OFF state and an ON state according to the control signal, wherein the input signal rises when the switching device is in the OFF state and the drops when the switching device is in the ON state, wherein the input signal is synchronized with the input source by phase.

15. The table method of controlling a power factor correction (PFC) circuit with arbitrary input waveforms of claim 8, wherein the feedback controller output is obtained by comparing an output voltage of the PFC circuit and a reference voltage, wherein the feedback controller output increases when the output voltage is lower than the reference voltage, and the feedback controller output decreases when the output voltage is higher than the reference voltage, wherein the reference voltage represents a desired power level of the output voltage.

16. An instantaneous method of controlling a power factor correction (PFC) circuit with arbitrary input waveforms, comprising:

sensing a first input power parameter;

taking an instantaneous value of the first input power parameter at fixed intervals;

multiplying the instantaneous value of the first input power parameter by a feedback controller output to generate a control signal; and

controlling a PFC circuit with the control signal, wherein a second input power parameter is synchronized with the first input power parameters.

17. The instantaneous method of controlling a power factor correction (PFC) circuit with arbitrary input waveforms of claim 16, further comprising:

recording a cycle maximum of the first input power parameter; and

dividing the instantaneous value of the first input power parameter by the cycle maximum.

18. The instantaneous method of controlling a power factor correction (PFC) circuit with arbitrary input waveforms of claim 16, wherein the first input power parameter is a constant input current and the second input power parameter is an input voltage.

19. The instantaneous method of controlling a power factor correction (PFC) circuit with arbitrary input waveforms of claim 16, wherein the first input power parameter is a constant input voltage and the second input power parameter is an input current.

20. The instantaneous method of controlling a power factor correction (PFC) circuit with arbitrary input waveforms of claim 16, further comprising:

switching a switching device between an OFF state and an ON state according to the control signal, wherein the second input power parameter rises when the switching device is in the OFF state and the drops when the switching device is in the On state, wherein the second input power parameter is synchronized with the first input power parameter.