PV Converter Rapid Shutdown via Autonomous Open-Circuit Detection

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Solution Overview

Problem

Existing solar power systems lack efficient mechanisms for rapid shutdown that can autonomously disconnect the PV array from the energy storage system without requiring communication between components, ensuring voltage levels on the roof are below 30V within 30 seconds for safety during emergencies.

Innovation Solution

Implementing PV converters with autonomous rapid shutdown detection logic that independently limit output voltage and current to prevent overvoltage, allowing for rapid disconnection of the PV array from the ESS-side without relying on communication, using voltage and current sensors to detect open circuit conditions and engage discharge resistors to quickly reduce bus voltages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If rapid shutdown is implemented by disconnecting PV array from ESS, then safety for emergency responders is improved (voltages below 30V within 30 seconds), but device complexity increases (requiring autonomous detection logic, voltage/current sensors, discharge resistors)

Engineering Contradiction:

Improvevoltage safetyVSAvoidshutdown mechanism complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The PV converter is designed to autonomously detect shutdown conditions and execute rapid shutdown without external communication. The controller monitors voltage and current signals, detects open circuit conditions, and automatically engages discharge resistors to reduce bus voltages below 30V within 30 seconds, making the system self-sufficient for safety-critical operations

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Discharge resistors are introduced as intermediary components that provide a controlled path for dissipating energy from DC bus capacitors during shutdown. These resistors enable rapid voltage reduction by creating a deliberate energy dissipation mechanism, allowing the system to meet the 30V within 30 seconds requirement without complex switching arrangements

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If autonomous detection logic is implemented in PV converters, then reliability of rapid shutdown is improved (independent operation without communication), but manufacturing precision requirements increase (accurate voltage/current sensing and control)

Engineering Contradiction:

Improveshutdown reliabilityVSAvoidsensing and control precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The controller continuously monitors voltage and current signals from sensors during operation and adjusts its behavior based on feedback. During shutdown detection, the controller monitors the evolution of voltage signals across DC bus capacitors and current signals, using this feedback to confirm open circuit conditions and verify successful engagement of discharge resistors, ensuring reliable autonomous operation

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system uses deliberately excessive sensing capabilities and control margins to ensure reliable detection. The controller monitors multiple signals (voltage across capacitors, line currents) and applies conservative detection thresholds, allowing for manufacturing tolerances while maintaining high reliability in autonomous shutdown detection

Inventive Principle:

Principle #16Partial or excessive action

3Ease of operation

If communication between components is eliminated for shutdown, then ease of operation is improved (simpler system operation), but loss of information increases (no coordination between PV converter and inverter)

Engineering Contradiction:

Improveshutdown operation simplicityVSAvoidsystem coordination information

Core Design Contradiction:

Ease of operationVSLoss of information

Solution Approach 1:

The rapid shutdown function is segmented into independent detection and execution components within the PV converter. The controller separately handles voltage monitoring, current monitoring, open circuit detection, and discharge resistor engagement, allowing each function to operate autonomously without requiring inter-component communication while maintaining operational simplicity

Inventive Principle:

Principle #1Segmentation

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

Enables rapid shutdown of solar power systems to ensure voltages on the roof are below 30V within 30 seconds, enhancing safety for emergency responders by avoiding overvoltage and reducing reliance on battery modules or communication.

Implementation Method 1

engage discharge resistors to quickly reduce bus voltages

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS12573838B2Autonomous detection of rapid shutdown condition

Publication Date: 2026.03.10 LUNAR ENERGY INC

AI summary

A rapid shutdown system includes a PV (photovoltaic) generator. It further includes a DC (Direct Current)-DC converter receiving power from the PV generator and outputting power. The DC-DC converter outputs power at a high voltage state or a low voltage state. It further includes a DC bus coupled to the DC-DC converter to receive the power outputted by the DC-DC converter. The DC bus is coupled to a system comprising a load. The DC-DC converter transitions from the high voltage state to the low voltage state based at least in part on an output current of the DC-DC converter transitioning below a threshold.