Inverter Circuit Efficiency via Segmented MOSFETs

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Solution Overview

Problem

Conventional inverter circuits for renewable energy systems, such as solar energy, face efficiency issues due to high turn-on losses from IGBTs and increased losses from body diodes in MOSFETs, resulting in efficiencies lower than 97%.

Innovation Solution

The inverter circuit employs independent diodes for freewheeling current instead of body diodes within PWM switches and uses three inductors with smaller inductances to reduce volume and cost, with CoolMOS devices and ordinary MOSFETs configured to enhance efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If IGBTs are employed as power switches, then the inverter circuit can handle high power applications, but the turn-on losses are quite large since the turn-on voltage drop exceeds 2V, resulting in efficiency lower than 97%

Engineering Contradiction:

Improvepower handling capabilityVSAvoidturn-on losses

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent segments the power switch function by using four MOSFETs (S1-S4) instead of two IGBTs, with each MOSFET handling specific switching tasks. This segmentation allows each device to operate in its optimal performance range, reducing overall conduction losses while maintaining high power handling capability through parallel configuration and complementary switching.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the key parameter from IGBT turn-on voltage drop (exceeding 2V) to MOSFET on-resistance characteristics. By selecting MOSFETs with low Rds(on) and optimizing their switching parameters, the circuit achieves lower conduction losses. The body diode forward voltage is also optimized through parameter selection to minimize freewheeling losses.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration increases efficiency to over 98%, reducing losses and costs, and allows for a more efficient conversion of solar cell output to AC power.

Implementation Method 1

an independent diode being employed to realize the freewheeling current instead of a body diode inside the PWM switch

Methodology Applied

Scientific EffectDiode conduction: Diode

Implementation Method 2

three inductors with relatively smaller inductances

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS8493761B2Inverter circuit having relatively higher efficiency

Publication Date: 2013.07.23 DELTA ELECTRONICS INC(CN)

AI summary

The configurations of an inverter circuit are provided in the present invention. The proposed circuit includes a first bridge arm having a first sub-bridge arm with a first switch and a first middle point coupled to the first switch, and a second sub-bridge arm with a second switch and a second middle point coupled to the second switch, a first inductor having a first terminal coupled to the first middle point and a second terminal, and a second inductor having a first terminal coupled to the second middle point, and a second terminal coupled to the second terminal of the first inductor and outputting an AC voltage.