Systems and methods for constant current control with primary-side sensing and regulation in various operation modes

• US 9,343,979 B2
• Filed: 11/07/2014
• Issued: 05/17/2016
• Est. Priority Date: 05/05/2011
• Status: Active Grant

• Current Assignee: Guangzhou On-Bright Electronics Co., Ltd
• Original Assignee: Guangzhou On-Bright Electronics Co., Ltd
• Inventors: Fang, Lieyi, Lin, Guo Wei
• Primary Examiner(s): Berhane, Adolf
• Assistant Examiner(s): DEMISSE, AFEWORK S
• Application Number:
  US14/536,514
• Publication Number:
  US 20150180347A1
• Time in Patent Office: 557 Days
• Field of Search: 363/21.15, 363/49, 363/56.12, 363/21.17, 363/21.18, 363/80, 363/79, 363/21.01
• US Class Current: 1/1
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 1/08 Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence
• CPC Class Codes: H02M 3/33515 with digital control
• 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

System and method for regulating a power converter. The system includes a first signal processing component configured to receive at least a sensed signal and generate a first signal. The sensed signal is associated with a primary current flowing through a primary winding coupled to a secondary winding for a power converter. Additionally, the system includes a second signal processing component configured to generate a second signal, an integrator component configured to receive the first signal and the second signal and generate a third signal, and a comparator configured to process information associated with the third signal and the sensed signal and generate a comparison signal based on at least information associated with the third signal and the sensed signal.

Claims

1. A system for regulating a power converter, the system comprising:

a first sampling-and-holding and voltage-to-current-conversion component configured to receive at least a sensed signal and generate a first current signal, the sensed signal being associated with a primary current flowing through a primary winding coupled to a secondary winding for a power converter;

a second sampling-and-holding and voltage-to-current-conversion component configured to receive at least the sensed signal and generate a second current signal;

a current-signal generator configured to generate a third current signal;

a capacitor coupled to the current-signal generator and coupled, through a switch, to the first sampling-and-holding and voltage-to-current-conversion component and the second sampling-and-holding and voltage-to-current-conversion component, the capacitor being configured to generate a voltage signal;

a comparator configured to process information associated with the voltage signal and the sensed signal and generate a comparison signal based on at least information associated with the voltage signal and the sensed signal;

a modulation-signal generator configured to receive at least the comparison signal and generate a modulation signal; and

a gate driver configured to receive the modulation signal and output a drive signal to a switch, the switch being configured to affect the primary current flowing through the primary winding;

wherein;

the drive signal is associated with at least one or more switching periods, each switching period of the one or more switching periods including at least an on-time period for the switch and a demagnetization period for a demagnetization process;

the first current signal represents the primary current at the beginning of the on-time period; and

the second current signal represents the primary current at the end of the on-time period;

wherein for each switching period of the one or more switching periods,

the first current signal and the second current signal discharge or charge the capacitor during only the demagnetization period;

the third current signal charges or discharges the capacitor during the switching period; and

the switching period multiplied by the third current signal is equal to the demagnetization period multiplied by a sum of the first current signal and the second current signal in magnitude.

2. The system of claim 1, and further comprising a low-pass filter coupled, directly or indirectly, to the capacitor and the comparator.

3. The system of claim 1 wherein:

the first sampling-and-holding and voltage-to-current-conversion component, the second sampling-and-holding and voltage-to-current-conversion component, the current-signal generator, the comparator, the modulation-signal generator, and the gate driver are located on a chip; and

the capacitor is located on or off the chip.

4. The system of claim 1 is configured to regulate an output current at a predetermined constant level in a discontinuous conduction mode and a continuous conduction mode.

5. The system of claim 1 is configured to regulate an output current at a predetermined constant level in a discontinuous conduction mode.

6. The system of claim 1 is configured to regulate an output current at a predetermined constant level in a continuous conduction mode.

7. A method for regulating a power converter, the method comprising:

receiving at least a sensed signal, the sensed signal being associated with a primary current flowing through a primary winding coupled to a secondary winding for a power converter;

processing information associated with the sensed signal;

generating a first current signal and a second current signal based on at least information associated with the sensed signal;

generating a third current signal;

processing information associated with the first current signal, the second current signal and the third current signal;

generating a voltage signal, by at least a capacitor, based on at least information associated with the first current signal, the second current signal and the third current signal;

processing information associated with the voltage signal and the sensed signal;

generating a comparison signal based on at least information associated with the voltage signal and the sensed signal;

receiving at least the comparison signal;

generating a modulation signal based on at least information associated with the comparison signal;

receiving the modulation signal; and

outputting a drive signal based on at least information associated with the modulation signal to affect the primary current flowing through the primary winding;

wherein;

the drive signal is associated with at least one or more switching periods, each switching period of the one or more switching periods including at least an on-time period and a demagnetization period;

the first current signal represents the primary current at the beginning of the on-time period; and

the second current signal represents the primary current at the end of the on-time period;

wherein for each switching period of the one or more switching periods, the process for processing information associated with the first current signal, the second current signal and the third current signal includes;

discharging or charging the capacitor with the first current signal and the second current signal during only the demagnetization period; and

charging or discharging the capacitor with the third current signal during the switching period;

wherein the switching period multiplied by the third current signal is equal to the demagnetization period multiplied by a sum of the first current signal and the second current signal in magnitude.

8. A system for regulating a power converter, the system comprising:

a sampling-and-holding and voltage-to-current-conversion component configured to receive at least a sensed signal and generate a first current signal, the sensed signal being associated with a primary current flowing through a primary winding coupled to a secondary winding for a power converter;

a current-signal generator configured to generate a second current signal;

a capacitor coupled to the current-signal generator and coupled, through a switch, to the sampling-and-holding and voltage-to-current-conversion component, the capacitor being configured to generate a voltage signal;

a comparator configured to process information associated with the voltage signal and the sensed signal and generate a comparison signal based on at least information associated with the voltage signal and the sensed signal;

a modulation-signal generator configured to receive at least the comparison signal and generate a modulation signal; and

a gate driver configured to receive the modulation signal and output a drive signal to a switch, the switch being configured to affect the primary current flowing through the primary winding;

wherein;

the drive signal is associated with at least one or more switching periods, each switching period of the one or more switching periods including at least an on-time period for the switch and a demagnetization period for a demagnetization process; and

the first current signal represents the primary current at the end of the on-time period;

wherein for each switching period of the one or more switching periods,

the first current signal discharges or charges the capacitor during only the demagnetization period;

the second current signal charges or discharges the capacitor during the switching period; and

the switching period multiplied by the second current signal is equal to the demagnetization period multiplied by the first current signal in magnitude.

9. The system of claim 8 wherein:

the sampling-and-holding and voltage-to-current-conversion component, the current-signal generator, the comparator, the modulation-signal generator, and the gate driver are located on a chip; and

the capacitor is located off the chip.

10. The system of claim 8 is configured to regulate an output current at a predetermined constant level in a quasi-resonant mode.

11. The system of claim 8, and further comprising a pulse-signal generator configured to output one or more signal pulses to the modulation-signal generator in response to one or more demagnetization pulses corresponding to one or more demagnetization periods.

12. A method for regulating a power converter, the method comprising:

receiving at least a sensed signal, the sensed signal being associated with a primary current flowing through a primary winding coupled to a secondary winding for a power converter;

processing information associated with the sensed signal;

generating a first current signal based on at least information associated with the sensed signal;

generating a second current signal;

processing information associated with the first current signal and the second current signal;

generating a voltage signal, by at least a capacitor, based on at least information associated with the first current signal and the second current signal;

processing information associated with the voltage signal and the sensed signal;

generating a comparison signal based on at least information associated with the voltage signal and the sensed signal;

receiving at least the comparison signal;

generating a modulation signal based on at least information associated with the comparison signal;

receiving the modulation signal; and

outputting a drive signal based on at least information associated with the modulation signal to affect the primary current flowing through the primary winding;

wherein;

the drive signal is associated with at least one or more switching periods, each switching period of the one or more switching periods including at least an on-time period and a demagnetization period; and

the first current signal represents the primary current at the end of the on-time period;

wherein for each switching period of the one or more switching periods, the process for processing information associated with the first current signal and the second current signal includes;

discharging or charging the capacitor with the first current signal during only the demagnetization period; and

charging or discharging the capacitor with the second current signal during the switching period;

wherein the switching period multiplied by the second current signal is equal to the demagnetization period multiplied by the first current signal in magnitude.