Power converting apparatus and method of sensing output current thereof

• US 8,519,776 B2
• Filed: 05/12/2011
• Issued: 08/27/2013
• Est. Priority Date: 12/13/2010
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Fairchild Korea Semiconductor Limited (ON Semiconductor Corporation)
• Inventors: Chung, Younwoong
• Primary Examiner(s): PATEL, RAJNIKANT B
• Application Number:
  US13/106,717
• Publication Number:
  US 20120146598A1
• Time in Patent Office: 838 Days
• Field of Search: 363 16- 17, 363/21.04, 363/21.05, 363/21.16, 363/21.17, 363/89, 363/97, 363/98, 363/79, 323/222, 323/224, 323/266, 323/267, 323/272, 323/275, 323/277, 323282-289, 323/280, 323/281, 327/108, 327/110, 327/176, 327/423, 327/427, 327/536, 327/541
• US Class Current: 327/536
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load

Abstract

A power converting apparatus includes a power converter, a first resistor, a second resistor, a current controller, a voltage sensor, a sample/holder, and a switch controller. The power converter converts an input voltage into an output voltage. The first resistor is connected to an output of the power converter, and the second resistor is connected to the first resistor. The current controller controls a first current to make the first current that is less than a second current flowing in the first resistor flow in the second resistor, and outputs a third current corresponding to the first current. The voltage sensor senses a first voltage corresponding to the third current. The sample/holder samples the first voltage, and outputs the sampled voltage. The switch controller controls an operation of the power converter based on a voltage output from the sample/holder.

Claims

1. A power converting apparatus, comprising:

a power converter configured to convert an input voltage into an output voltage;

a first resistor connected to an output of the power converter;

a second resistor connected to the first resistor;

a current controller configured to control a first current to make the first current that is less than a second current flowing in the first resistor flow in the second resistor, and to output a third current corresponding to the first current;

a voltage sensor configured to sense a first voltage corresponding to the third current;

a sample/holder configured to sample the first voltage, and to output the sampled voltage; and

a switch controller configured to control operation of the power converter based on a voltage output from the sample/holder.

2. The apparatus of claim 1, wherein the third current is equal to the first current.

3. The apparatus of claim 1, wherein the power converter comprises:

a power storing unit configured to receive the input voltage;

an output unit configured to output the output voltage; and

a switching unit configured to control a connection between the power storing unit and the output unit,

wherein the power storing unit stores power according to the input voltage while the switching unit blocks the power storing unit from the output unit, and

the output unit generates the output voltage from the power stored to the power storing unit while the switching unit connects the power storing unit to the output unit.

4. The apparatus of claim 3, wherein the sample/holder samples the first voltage while the switching unit blocks the power storing unit from the output unit, and outputs the sampled voltage while the switching unit connects the power storing unit to the output unit.

5. The apparatus of claim 3, wherein the switching unit controls the connection between the power storing unit and the output unit in response to a control signal from the switch controller, and

the sample/holder samples the first voltage or outputs the sampled voltage in response to the control signal.

6. The apparatus of claim 3, wherein the first resistor has a first terminal connected to the output unit, and a second terminal, and

the second resistor has a first terminal connected to the second terminal of the first resistor, and a second terminal,

wherein the current controller comprises:

a comparator having a first input terminal connected to the first terminal of the first resistor, a second input terminal connected to the second terminal of the second resistor, and an output terminal; and

a transistor having an input terminal connected to the second terminal of the second resistor, a control terminal connected to the output terminal of the comparator, and an output terminal connected to the voltage sensor,

wherein the third current flows in the transistor.

7. The apparatus of claim 6, wherein the second resistor has greater resistance than the first resistor.

8. The apparatus of claim 6, wherein the first input terminal is a positive input terminal and the second input terminal is a negative input terminal, and

wherein the transistor is a p-channel transistor, and the input terminal, the control terminal, and the output terminal of the transistor correspond to a source, a gate, and a drain, respectively.

9. The apparatus of claim 6, wherein the voltage sensor comprises a third resistor connected between the output terminal of the transistor and a predetermined voltage terminal.

10. The apparatus of claim 6, wherein the second terminal of the first resistor is further connected to a ground terminal.

11. The apparatus of claim 3, wherein the power storing unit comprises an inductor having a first terminal connected to the input voltage, and a second terminal,

the switching unit comprises a diode having an anode connected between the second terminal of the inductor, and a cathode, and a switch connected between the second terminal of the inductor and a ground terminal,

wherein the output unit comprises a capacitor connected between the cathode of the diode and the first resistor.

12. The apparatus of claim 11, wherein the power storing unit is blocked from the output unit when the switch is turned on, and the power storing unit is connected to the output unit when the switch is turned off.

13. A method of sensing an output current flowing in an output unit of a power converting apparatus, the method comprising:

storing power according to an input voltage while the input voltage is blocked from the output unit; and

generating an output voltage of the output unit based on the stored power, and

wherein storing the power comprises;

generating a first current that is less than the output current flowing in the output unit;

sensing a voltage according to a second current corresponding to the first current; and

sampling the sensed voltage,

wherein generating the output voltage comprises;

outputting the sampled voltage; and

controlling an operation of the power converting apparatus based on the sampled voltage.

14. The method of claim 13, wherein the power converting apparatus includes a first resistor having a first terminal connected to the output unit and a second terminal, and a second resistor having a first terminal connected to the second terminal of the first resistor and a second terminal, and

generating the first current comprises:

regulating a voltage of the second terminal of the second resistor to be equal to a voltage of the first terminal of the first resistor; and

generating the first current from a current flowing in the second resistor.

15. The method of claim 14, wherein the third current is equal to the second current.

16. The method of claim 15, wherein the power converting apparatus further includes an inductor, and the output unit includes a capacitor,

wherein storing the power further comprises providing a current to the inductor from the input voltage to store the power to the inductor, and

wherein generating the output voltage further comprises storing the output voltage to the capacitor with a current flowing in the inductor.

17. A power converting apparatus, comprising:

a power converter including a capacitor, and configured to convert an input voltage into an output voltage to store the output voltage to the capacitor;

a first resistor having a first terminal connected to the capacitor, and a second terminal;

a second resistor having a first terminal connected to the second terminal of the first resistor, and a second terminal;

a comparator having a first input terminal connected to the first terminal of the first resistor, a second input terminal connected to the second terminal of the second resistor, and an output terminal;

a transistor having a control terminal connected to the output terminal of the comparator, an input terminal connected to the second terminal of the second resistor, and an output terminal;

a third resistor connected to the output terminal of the transistor;

a sample/holder configured to sample a voltage of the third resistor, and to output the sampled voltage; and

a switch controller configured to control an operation of the power converter based on a voltage output from the sample/holder.

18. The apparatus of claim 17, wherein the second resistor has greater resistance than the first resistor.

19. The apparatus of claim 17, wherein the second terminal of the first resistor is further connected to a ground terminal.

20. The apparatus of claim 17, wherein the first input terminal is a positive input terminal, and the second input terminal is a negative input terminal, and

wherein the transistor is a p-channel transistor, and the input terminal, the control terminal, and the output terminal of the transistor correspond to a source, a gate, and a drain, respectively.