ANPC Inverter Overcurrent Protection Control Sequence

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Active neutral point clamped (ANPC) inverter apparatuses face damage from excessive voltage stress due to inappropriate turn-off and turn-on sequences of switch elements during overcurrent states, leading to inefficiencies and higher costs.

Innovation Solution

The inverter apparatus employs a control unit to manage the sequence of turning off and on switch elements, prioritizing the high-frequency switching elements first and ensuring the freewheeling path is stable to prevent excessive voltage stress, using specific control types to manage current paths and reduce voltage stress across switch elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If switch elements are turned off during overcurrent state to protect ANPC inverter apparatus, then overcurrent protection is achieved, but excessive voltage stress damages switch elements due to inappropriate turn-off and turn-on sequence

Engineering Contradiction:

Improveovercurrent protectionVSAvoidexcessive voltage stress

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The control unit determines the current flowing through each switch element before turning them off, and based on this preliminary assessment, establishes a safe turn-off sequence that prevents excessive voltage stress. This preliminary current determination ensures that switch elements are turned off in an order that protects against voltage damage while achieving overcurrent protection.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control unit continuously monitors the current flowing through each switch element and uses this feedback information to dynamically adjust the turn-off sequence. By incorporating real-time current feedback, the system optimizes the switching sequence to minimize voltage stress on individual switch elements while maintaining effective overcurrent protection.

Inventive Principle:

Principle #23Feedback

2Productivity

If switch elements are turned off to limit current, then overcurrent state is controlled, but switch element damage occurs due to excessive voltage stress

Engineering Contradiction:

Improvecurrent limitingVSAvoidswitch element durability

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

Before executing the turn-off sequence to limit current, the control unit preliminarily determines the current through each switch element and plans a turn-off sequence that anticipates and prevents excessive voltage stress. This preliminary planning allows current limiting to proceed while protecting switch element durability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control unit changes the operational parameters of switch elements by adjusting their turn-off sequence based on real-time current conditions. By dynamically changing which switch element turns off first, the system maintains current limiting effectiveness while reducing voltage stress on individual elements, thereby preserving their durability.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If inappropriate turn-on sequence is used after overcurrent state, then switch elements remain protected, but voltage stress still damages switch elements

Engineering Contradiction:

Improveswitch element protectionVSAvoidvoltage stress during turn-on

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The control unit preliminarily determines the current through each switch element before turning them on after an overcurrent event. This preliminary current assessment enables the control unit to establish a turn-on sequence that prevents excessive voltage stress, ensuring that switch elements are turned on in an order that protects them from voltage damage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control unit uses real-time current feedback to dynamically adjust the turn-on sequence of switch elements. By monitoring current conditions and incorporating this feedback into the switching decision, the system optimizes the turn-on sequence to minimize voltage stress on switch elements while maintaining their protection status.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP3595161B1Inverter apparatus with overcurrent protection control

Publication Date: 2022.06.29 DELTA ELECTRONICS INC(CN)

Figure 1
Figure 2
Figure 3A

AI summary

An inverter apparatus (100) with overcurrent protection control includes a first terminal (IN1) of a DC input terminal (IN) connected to an AC output terminal (OUT) through a first switch element (Q1) and a second switch element (Q2), and a second terminal (In2) of the DC input terminal (IN) connected to the AC output terminal (OUT) through a fourth switch element (Q4) and a third switch element (Q3). An intermediate potential terminal (INC) is connected to a fifth switch element (Q5) and a sixth switch element (Q6), and connected to the AC output terminal (OUT) through the fifth switch element (Q5) and the second switch element (Q2), and connected to the AC output terminal (OUT) through the sixth switch element (Q6) and the third switch element (Q3). When the control unit (20) determines that the inverter apparatus (100) is in an overcurrent state, the control unit (20) controls a sequence of turning off the inverter apparatus (100) to be the second switch element (Q2), the first switch element (Q1), and the sixth switch element (Q6).