Controller and method for adaptive speed control of a fan array
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Solution Overview
Problem
Fan arrays in air handling units experience decreased output and operational inefficiencies when one or more fans fail, affecting occupant comfort and energy performance, with existing systems failing to effectively maintain airflow and extend equipment lifetime.
Innovation Solution
A control approach that includes a fault detection and diagnostic module and a fan speed control module, which identifies a fan speed command, scales it based on a floating maximum fan speed, adjusts the speed in response to fan errors, and rescales the command to maintain airflow and extend equipment life by redistributing load within the fan array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fan arrays operate with one or more fans failed, then the system continues to provide air flow, but the overall output and energy performance decrease
Solution Approach 1:
The system dynamically changes the operating parameters of the remaining functional fans by adjusting their speeds. When a fan failure is detected, the controller increases the speed of the remaining fans to compensate for the lost capacity, thereby maintaining overall air flow output while continuing to operate in a degraded mode
Solution Approach 2:
The fan array system transitions from a static operating mode to a dynamic adaptive mode. The controller continuously monitors fan status and automatically adjusts the operational parameters of the remaining fans in real-time based on the detected failure conditions, enabling the system to adapt its performance to maintain productivity despite component failures
2Reliability
If fan arrays operate with one or more fans failed, then the system continues to provide air flow, but energy performance deteriorates
Solution Approach 1:
The system optimizes energy consumption by dynamically adjusting the speed parameters of the remaining functional fans. Rather than operating all fans at maximum speed or maintaining fixed speeds, the controller modulates the speed of each operational fan to achieve the required air flow output with minimum energy expenditure, accounting for the reduced capacity due to fan failures
3Productivity
If fan speed is increased to compensate for fan failure, then air flow output is maintained, but wear on remaining fans increases
Solution Approach 1:
The system implements a feedback mechanism where the controller continuously monitors the operational status, performance, and wear indicators of the remaining fans. Based on this feedback, the controller dynamically adjusts the speed commands to balance the need for maintaining air flow output with the need to limit excessive wear, preventing any single fan from being overloaded beyond safe operational thresholds
Solution Approach 2:
Rather than uniformly increasing the speed of all remaining fans to maximum compensation levels, the system applies partial action by selectively adjusting speeds based on individual fan conditions, operational history, and current load requirements. This prevents excessive action that would accelerate wear while still achieving sufficient compensation to maintain required air flow output
Data Source
AI summary
There is described controllers, methods, and non-transitory computer readable medium for adaptive speed control of a fan array of an air handling unit. A fan speed command for the fan array is identified. The fan speed command is scaled based on a floating maximum fan speed. A fan error of at least one fan of the fan array is detected. The floating maximum fan speed is adjusted in response to detecting the fan error. The fan speed command is rescaled based on the adjusted floating maximum fan speed. The fan speed command is provided to each fan of the fan array.