Frequency Regulated Hysteretic Average Current Mode Converter

• US 20080067993A1
• Filed: 09/13/2007
• Published: 03/20/2008
• Est. Priority Date: 09/16/2006
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Coleman, Edward P.
• Granted Patent: US 8,054,056 B2
• Time in Patent Office: Days
• US Class Current: 323/282
• CPC Class Codes: H02M 1/0025 Arrangements for modifying reference values, feedback values or error values in the control loop of a converter
• CPC Class Codes: H02M 1/0029 Circuits or arrangements for limiting the slope of switching signals, e.g. slew rate
• CPC Class Codes: H02M 1/15 using active elements
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 1/40 Means for preventing magnetic saturation
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators

Abstract

A switch mode power converter that precisely controls average switching current and operating frequency. The switching control operative in hysteretic average current mode control provides wide bandwidth operation without the need for slope correction. The switching converter ripple current is varied by a frequency comparator in response to a comparison of the switching frequency to a reference frequency. The ripple current is adjusted to obtain correlation between the operating switching frequency and the reference frequency. Peak current levels are precisely controlled and may be limited to prevent component stress levels from being exceeded. Current levels are continuously monitored with a current sense amplifier, or monitored with a high-gain low energy current sampler. Feedback loop independent line and load regulation is provided by continuous current monitoring, or by using variable slope charge and transfer voltage to pulse width converters when operating with a current sampler based system.

Claims

1. A power converter for controlling average switching current and operating frequency, said power converter comprising:

a switching control, operative in an hysteretic average current mode control for providing wide bandwidth operation without the need for slope correction;

a frequency comparator for varying a ripple current in response to a comparison of a switching frequency to a reference frequency;

wherein the ripple current is adjusted to obtain correlation between the switching frequency and the reference frequency;

a controller for controlling current levels to prevent component stress levels from exceeding a threshold; and

an amplifier for monitoring current levels.

2. The power converter of claim 1, wherein said amplifier is a current sense amplifier.

3. The power converter of claim 1, wherein said amplifier is a high-gain low-energy current level amplifier.

4. The power converter of claim 1, wherein a feedback loop independent line and regulation of load is provided by continuous ripple current monitoring.

5. The power converter of claim 1, further comprising:

a transfer voltage to pulse width converter.

6. A method for controlling average switching current and operating frequency, said method comprising:

varying a ripple current in response to a comparison of a switching frequency to a reference frequency;

adjusting the ripple current to obtain a correlation between the switching frequency and the reference frequency;

controlling a plurality of current levels;

monitoring the ripple current levels, wherein a feedback loop independent line and load regulation is provided by continuous ripple current monitoring.

7. The method of claim 6, wherein monitoring is performed by using variable slope charge and transfer voltage to pulse width converter when operating with a current sampler based system.

8. A system for providing power conversion, said system comprising:

a plurality of voltage-to-current power converters coupled in parallel with other at least one voltage-to-current power converter comprising;

switching control, operative in an hysteretic average current mode control for providing wide bandwidth operation without the need for slope correction;

a frequency comparator for varying a ripple current in response to a comparison of a switching frequency to a reference frequency;

wherein the ripple current is adjusted to obtain correlation between the switching frequency and the reference frequency;

a controller for controlling current levels to prevent component stress levels from exceeding a threshold; and

an amplifier for monitoring current levels.

9. The system of claim 8, wherein said amplifier is a current sense amplifier.

10. The system of claim 8, wherein said amplifier is a high-gain low-energy current level amplifier.

11. The system of claim 8, wherein a feedback loop independent line and regulation of load is provided by continuous ripple current monitoring.

12. The system of claim 8, further comprising:

a transfer voltage to pulse width converter.