HERIC Overvoltage Absorption Circuit with SiC Diodes

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing overvoltage absorption circuits based on HERIC topology face challenges in balancing absorption loss and absorption effect, leading to low conversion efficiency and severe heating of resistors, which affects the performance of photovoltaic grid-connected systems.

Innovation Solution

An overvoltage absorption circuit is introduced, featuring a single-phase HERIC topology with a clamping capacitor and absorption resistor connected in parallel, along with silicon carbide diodes, to effectively manage overvoltage across transistors, reducing operating loss and maintaining stable voltage levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an RC type or RCD type circuit structure is used to absorb overvoltage, then overvoltage absorption effect is achieved, but absorption loss increases and conversion efficiency decreases

Engineering Contradiction:

Improveovervoltage absorption effectVSAvoidabsorption loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent changes the circuit topology from traditional RC or RCD structures to a novel configuration using two diodes and two capacitors connected to a common coupling point. This topological parameter change enables the circuit to absorb overvoltage while reducing energy loss by allowing recovered energy to be stored in the capacitor rather than dissipated in resistors.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful overvoltage energy into beneficial stored energy by using the diode-capacitor configuration to capture and store the energy from cross-transistor switching events. The energy that would normally be lost as heat in resistor-based absorption circuits is instead stored in the capacitor, turning a harmful effect into a useful energy recovery mechanism.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If resistor-based overvoltage absorption circuits are used, then overvoltage is absorbed, but resistors are severely heated which reduces system conversion efficiency

Engineering Contradiction:

Improveovervoltage protectionVSAvoidresistor heating

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent eliminates the need for dissipative resistors by using a capacitor-based energy storage approach. The overvoltage energy that would cause resistor heating is instead stored in the capacitor, converting a harmful thermal effect into a useful energy storage function. This removes the heating problem entirely while maintaining overvoltage protection.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent substitutes the thermal dissipation mechanism (resistors converting electrical energy to heat) with an electrical energy storage mechanism (capacitors storing electrical energy). This substitution replaces the mechanical/thermal field with the electrical field, eliminating the heating issue while achieving the same protective function.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

The solution significantly reduces operating loss by minimizing additional energy absorption, maintaining efficient conversion efficiency while preventing resistor heating, thus enhancing the performance of photovoltaic grid-connected systems.

Implementation Method 1

an absorption circuit formed by a resistor R390 and a capacitor C1... An overvoltage generated by the third power transistor Q3 is absorbed by an absorption circuit formed by a resistor R390 and a capacitor C1

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

the resistor R390 and the capacitor C1... An overvoltage generated by the third power transistor Q3 is absorbed by an absorption circuit formed by a resistor R390 and a capacitor C1... the resistor R390 and the resistor R392 may be heated severely

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS11374401B2Overvoltage absorption circuit and single-phase heric topology

Publication Date: 2022.06.28 SUNGROW (SHANGHAI) CO LTD

AI summary

An overvoltage absorption circuit and a single-phase HERIC topology are provided. The overvoltage absorption circuit is applicable to the single-phase HERIC topology, and includes a clamping capacitor, an absorption resistor, a first diode, and a second diode. One terminal of the clamping capacitor and one terminal of the absorption resistor are each connected to collectors of two cross transistors in the single-phase HERIC topology. The other terminal of the clamping capacitor and the other terminal of the absorption resistor are each connected to the anodes of the first diode and the second diode. The cathode of the first diode is connected to the emitter of one of the two cross transistors. The cathode of the second diode is connected to the emitter of the other of the two cross transistors.