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Lossless inductor current sensing in a switch-mode power supply

A technology of switching mode power supplies and inductors, applied in the direction of measuring current/voltage, high-efficiency power electronic conversion, instruments, etc., can solve the problem of reducing the accuracy of operating conditions of SMPS

Inactive Publication Date: 2013-09-25
MICROCHIP TECH INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, this complementary filter must be compatible with the equivalent inductance L of the inductor 108 and the series resistance R L Matched for precise and absolute current measurements
This circuit also suffers from high temperature coefficients due to discrete component values ​​changing over the operating temperature range, thereby reducing accuracy over the range of operating conditions of the SMPS

Method used

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  • Lossless inductor current sensing in a switch-mode power supply
  • Lossless inductor current sensing in a switch-mode power supply
  • Lossless inductor current sensing in a switch-mode power supply

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[0031] Reference is now made to the drawings, which schematically illustrate details of certain example embodiments. In the drawings the same elements will be represented by the same numerals, and like elements will be represented by the same numerals with different lowercase letter suffixes.

[0032] The matched filter shown in FIG. 5 is the basis for a new, novel and non-obvious system, method and apparatus for non-destructively measuring SMPS power inductor current according to the teachings of the present invention. In a specific example embodiment ( Figure 6 ), a matched complementary filter is integrated into the SMPS controller by utilizing a tunable filter including an operational transconductance amplifier (OTA), a variable resistor, and a variable capacitor. In another specific example embodiment, an operational amplifier configured as a buffer and a variable resistor have been added, which provide independent gain and pole position adjustments ( Figure 7 ).

[0...

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Abstract

A lossless inductor current sense technique integrates a matched, tunable complimentary filter with a switch mode power supply (SMPS) controller for accurately measuring current through the power inductor of the SMPS without introducing losses in the power circuit. The complimentary filter can be adjusted in-circuit to significantly reduce the effects of component tolerances, accurately measuring the power inductor current for over current protection and / or closed loop control. The frequency pole and gain of the complimentary integrated filter can be adjusted on the fly in order to adapt to dynamically changing operating conditions of the SMPS system.

Description

technical field [0001] The present invention relates to switched mode power supplies, and more particularly to lossless inductor current sensing in switched mode power supplies (SMPS) with matched complementary tunable filters. Background technique [0002] The synchronous buck switch-mode power converter is a common topology used in SMPS applications. Current sensing in this topology can be challenging and must be overcome in the design. Knowing or monitoring the current injected into the load protects the power converter and can improve dynamic performance during its closed loop control. [0003] Some prior art current sensing techniques are as follows: series sense resistor in main power path, current sense transformer, sensing voltage drop across MOSFET switch, and inductor voltage by using auxiliary winding for power inductor 108 Integral measurement. Reference is now made to FIG. 1 , which depicts a prior art SMPS with a series sense resistor 110 in the main power p...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M3/156
CPCH02M3/1588Y02B70/10H02M1/0009G01R19/165
Inventor 斯考特·迪尔伯恩
Owner MICROCHIP TECH INC