Totem-Pole PFC Drive Logic for Freewheeling Switch Zero Crossing

Solution Overview

Problem

In totem pole power factor correction converters, the inductive current reversal during discontinuous conduction mode leads to additional losses and reduced power factor, as the driving voltage of the freewheeling switch continues to conduct when the inductive current drops to zero.

Innovation Solution

A driving circuit device that includes a controller, a current judgment circuit, a selector, and a calculator to adjust the driving voltage of the switching tube, ensuring it turns off when the inductive current crosses zero, preventing reverse conduction and using logical operations to generate a target drive level for the switching tube.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the driving voltage of the freewheeling switch continues to conduct during DCM mode, then the switching tube remains on to maintain continuous current flow, but the inductive current reverses direction causing additional losses and reduced power factor

Engineering Contradiction:

Improvecontinuous current flowVSAvoidadditional losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent employs feedback control by detecting the inductive current status and using this information to control the driving voltage of the freewheeling switch. The current detection unit monitors the inductive current, and the control unit adjusts the driving voltage based on the detection result, ensuring the switching tube turns off when current reaches zero, thereby preventing reverse current and energy losses.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies preliminary action by proactively controlling the driving voltage to become ineffective before the inductive current can reverse direction. The control unit anticipates the zero-crossing point of the inductive current and adjusts the driving voltage accordingly, preventing the harmful reverse current from occurring in the first place.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the driving voltage of the freewheeling switch continues to conduct during DCM mode, then the switching tube remains on, but the power factor decreases due to reverse conduction

Engineering Contradiction:

Improveswitching tube conductionVSAvoidpower factor reduction

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent employs feedback control by detecting the inductive current status and using this information to control the driving voltage of the freewheeling switch. The current detection unit monitors the inductive current, and the control unit adjusts the driving voltage based on the detection result, ensuring the switching tube turns off when current reaches zero, thereby preventing reverse current and energy losses.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies preliminary action by proactively controlling the driving voltage to become ineffective before the inductive current can reverse direction. The control unit anticipates the zero-crossing point of the inductive current and adjusts the driving voltage accordingly, preventing the harmful reverse current from occurring in the first place.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If complementary driving voltages are used for the two high-frequency switching tubes, then simple control is achieved, but the freewheeling switch continues conducting when inductive current drops to zero

Engineering Contradiction:

Improvecontrol simplicityVSAvoidenergy losses

Core Design Contradiction:

Ease of operationVSLoss of energy

Solution Approach 1:

The patent employs feedback control by detecting the inductive current status and using this information to control the driving voltage of the freewheeling switch. The current detection unit monitors the inductive current, and the control unit adjusts the driving voltage based on the detection result, ensuring the switching tube turns off when current reaches zero, thereby preventing reverse current and energy losses.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies dynamics by making the driving voltage control adaptive rather than fixed. The control unit dynamically adjusts the driving voltage based on the real-time status of the inductive current, transitioning from a static complementary control scheme to a dynamic control scheme that responds to operating conditions, thereby preventing energy losses during DCM mode.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS20240291381A1Driving circuit device and driving method of totem-pole power factor correction converter

Publication Date: 2024.08.29 OMNION POWER TECHNOLOGY GMBH

AI summary

In one embodiment, a driving circuit device for a totem pole power factor correction converter (PFC) includes: a controller configured to control an initial drive level of a switching tube of the converter; a current judgment circuit configured to determine whether the inductive current of the converter crosses zero or not; a selector configured to compare a power supply voltage of the converter with zero and select, based on a result of the comparison, one of an output level of the current judgment circuit and a preset logic level as an intermediate control level to be output; and an calculator configured to perform a logical operation on the intermediate control level and the initial drive level to generate a target drive level for driving the switching tube.