Isolated input current sense means for high power factor rectifier

• US 5,572,416 A
• Filed: 06/09/1994
• Issued: 11/05/1996
• Est. Priority Date: 06/09/1994
• Status: Expired due to Fees

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Murphy, Robert J. Jr., Farrington, Richard W., Jacobs, Mark E.
• Primary Examiner(s): NGUYEN, MATTHEW VAN
• Application Number:
  US08/255,624
• Time in Patent Office: 880 Days
• Field of Search: 363/16, 363/17, 363/21, 363/89, 363/125, 363/127, 323/222, 323/282, 323/284, 324/103 R, 324/103 P
• US Class Current: 363/89
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• 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
• CPC Class Codes: Y02P 80/10 Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier

Abstract

A converter for enhancing power factor utilizes a line sense winding magnetically coupled to sense a voltage across a line inductor in the input of a high power factor power converter. This winding in the illustrative embodiment is typically a single turn. This winding provides a measurement of the derivative (with respect to time) of the line current, and a specially designed integrator connected to the winding provides the estimate of the line current. An integrator is operative to accurately estimate the current by using known properties of this current to prevent mismeasurement due to reconstructing the "constant of integration" and any small biases in the integrator which normally cause errors.

Claims

1. An AC to DC Power Converter connected to an AC line;

including;

an input rectifier connected to the AC line;

a switching regulator connected to receive rectified AC from the input rectifier through an input inductor;

sensing means for monitoring a current flow between the rectifier and switching regulator through the input inductor;

the sensing means including;

a sense winding magnetically coupled to the input inductor;

an integrating circuit connected to receive at an input the output voltage of the sense winding;

a valley detector connected to an output of the integrating circuit and including circuitry for detecting and storing a voltage minimum of the output of the integrating circuit; and

a feedback connection coupling the voltage output of the valley detector to an input of the integrating circuit.

2. An AC to DC Power Converter as claimed in claim 1, further including drift circuitry for allowing a voltage output of the valley detector to drift upward at a controlled rate.

3. An AC to DC Power Converter as claimed in claim 1, further including:

control means connected for controlling intermittent switching of a power switch of the switching regulator in response to an output of the integrating means.

4. An AC to DC Power Converter as claimed in claim 1, wherein the switching regulator is a boost converter.

5. An AC to DC Power Converter as claimed in claim 1, wherein the switching regulator is a SEPIC converter.

6. An AC to DC Power Converter as claimed in claim 1, wherein the switching regulator includes an IGBT power switching device.

7. An AC to DC Power Converter as claimed in claim 1, wherein the switching regulator includes a FET power switching device.

8. An AC to DC Power Converter as claimed in claim 1, wherein the circuitry for allowing a voltage to drift upward includes a RC circuit connected to allow a voltage of its capacitor while charging to control a drift rate of the voltage level at the output.

9. An AC to DC Power Converter as claimed in claim 1, wherein the rectifier is a full wave bridge rectifier.

10. An AC to DC Power Converter as claimed in claim 1, wherein the integrating circuit includes an integrating operational amplifier.

11. An AC to DC Power Converter as claimed in claim 1, further including an output, and a diode connecting the input inductor to the output.

12. An AC to DC Power Converter as claimed in claim 11, further including a filter capacitor connected to the output.

13. An AC to DC Power Converter as claimed in claim 3 wherein the control means includes a PWM controller for controlling conduction of the power switch in short intervals at a frequency substantially greater than that of the AC line.

14. An AC to DC Power Converter connected to an AC line;

including;

an input full wave bridge rectifier connected to the AC line;

a switching regulator including a power switching device and connected to receive rectified AC from the input rectifier through an input inductor;

an output, and a diode connecting the input inductor to the output;

sensing means including a sense winding magnetically coupled to the input inductor, for monitoring a current flow between the rectifier and switching regulator through the input inductor;

the sensing means including;

an integrating circuit including an integrating operational amplifier connected to receive at an input the output voltage of the sense winding;

a valley detector connected to an output of the integrating circuit and including circuitry for detecting and storing a voltage minimum of the output of the integrating circuit and the circuitry for storing including a drift control circuit connected to allow a voltage of its capacitor while charging to control a drift rate of the voltage level at the output and operative for allowing a voltage output of the valley detector to drift upward at a controlled rate; and

control means including a PWM controller connected for controlling intermittent switching of the power switch of the switching regulator at a frequency greater than that of the AC line in response to an output of the integrating means.

15. An AC to DC Power Converter as claimed in claim 14, wherein the switching regulator is a boost converter.

16. An AC to DC Power Converter as claimed in claim 14, wherein the switching regulator is a SEPIC converter.

17. An AC to DC Power Converter as claimed in claim 14, wherein the switching regulator includes a Flit power switching device.

18. An AC to DC Power Converter as claimed in claim 14, wherein the switching regulator includes an IGBT power switching device.

19. A boost power converter connected to be powered from an AC line and operative for enhancing the power factor at its input, comprising:

a rectifier connected to receive energy off of the AC line;

a boost inductor connected to receive the rectified signal output of the rectifier;

a power switch enabled conducting in short intervals as compared to a period of a signal supplied by the AC line and connected to draw current flow from the rectifier through the boost inductor;

a diode for coupling an output of the boost inductor to an output terminal;

a filter capacitor connected for sustaining a DC output voltage;

a PWM controller for controlling the conduction of the power switch in short intervals;

current sensing means connected for sensing a current flow through the rectifier and for applying a sense signal to the PWM controller;

the current sensing means including;

an integrator adapted to compensate for the integration constant and remove offset bias voltages comprising an integrating operational amplifier and a valley detector connected to detect voltage minima of the output of the integrating operational amplifier and supply a feedback signal representing the voltage minima to an input of the integrating operational amplifier.

20. An AC to DC Power Converter connected to an AC line;

including;

an input rectifier connected to the AC line;

a switching regulator connected to receive rectified AC from the input rectifier through an input inductor;

sensing means for monitoring a current flow between the rectifier and switching regulator through the input inductor;

including;

a sense winding magnetically coupled to the input inductor;

an integrating circuit connected to receive at an input the output voltage of the sense winding;

a peak detector connected to an output of the integrating circuit and including circuitry for detecting and storing a voltage peak of the output of the integrating circuit; and

a feedback connection coupling the voltage output of the peak detector to an input of the integrating circuit.

21. An AC to DC Power Converter as claimed in claim 20, further including drift circuitry for allowing a voltage output of the peak detector to drift downward at a controlled rate.

22. A boost power converter connected to be powered from an AC line and operative for enhancing the power factor at its input, comprising:

a rectifier connected to receive energy off of the AC line;

a boost inductor connected to receive the rectified signal output of the rectifier;

a power switch enabled conducting in short intervals as compared to a period of a signal supplied by the AC line and connected to draw current flow from the rectifier through the boost inductor;

a diode for coupling an output of the boost inductor to an output terminal;

a filter capacitor connected for sustaining a DC output voltage;

a PWM controller for controlling the conduction of the power switch in short intervals;

current sensing means connected for sensing a current flow through the rectifier and for applying a sense signal to the PWM controller;

the current sensing means including;

an integrator adapted to compensate for the integration constant and remove offset bias voltages comprising an integrating operational amplifier and a peak detector connected to detect voltage peaks of the output of the integrating operational amplifier and including circuitry to supply a feedback signal representing the voltage peaks to an input of the integrating operational amplifier.