HVAC Load Manager for Staggered Motor Startup Peak Control

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Solution Overview

Problem

HVAC systems impose significant peak loads on electrical distribution grids, leading to potential brownouts or blackouts and increased costs for utilities to accommodate excess capacity, necessitating methods to reduce peak demand.

Innovation Solution

An HVAC system with a load manager that coordinates the operation of electric motors to prevent simultaneous startup, using a communication network to manage the timing of motor operations and distribute the electrical load more evenly, thereby reducing inrush current spikes and peak demand.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple HVAC systems operate simultaneously to meet cooling demands, then the cooling service is improved, but the peak electrical load on the power grid increases causing brownouts or blackouts

Engineering Contradiction:
Improvecooling service availabilityVSAvoidpeak electrical load
Core Design Contradiction:
ReliabilityVSPower

Solution Approach 1:

The system implements periodic staggered startup sequences where HVAC systems are activated in alternating time intervals rather than simultaneously. The load manager coordinates startup timing so that systems operate in a rotating pattern, ensuring continuous cooling coverage while distributing peak load demands across different time periods.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The load manager predicts peak demand periods in advance and pre-cools spaces by activating HVAC systems before the predicted peak occurs. This preliminary cooling action reduces the need for all systems to operate at full capacity during peak periods, thereby lowering peak electrical load while maintaining cooling reliability.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If electric utilities design power generation and distribution systems with excess capacity to accommodate peak loads, then the reliability of power supply is improved, but the cost of infrastructure increases

Engineering Contradiction:
Improvepower supply reliabilityVSAvoidexcess infrastructure capacity
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The load manager receives feedback from the utility company regarding current and predicted peak demand periods. Based on this feedback, the system dynamically adjusts HVAC operation schedules to shift load away from peak periods, enabling utilities to operate existing infrastructure at optimal capacity without requiring excessive redundant capacity.

Inventive Principle:
Principle #23Feedback

3Power

If the load manager coordinates HVAC startup sequences to reduce peak demand, then the electrical load on power grids is reduced, but the complexity of the control system increases

Engineering Contradiction:
Improvepeak electrical load reductionVSAvoidcontrol system complexity
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The load manager serves as an intermediary device that receives simple inputs from HVAC systems and utility feedback, then automatically generates coordinated startup sequences. This intermediary approach simplifies the overall system architecture by centralizing the coordination logic in a single device rather than requiring complex peer-to-peer communication between multiple HVAC controllers.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP2420750B1HVAC System
Publication Date: 2023.05.03 LENNOX IND INC
  • EP2420750B1 patent drawingFigure 1
  • EP2420750B1 patent drawingFigure 2~3
  • EP2420750B1 patent drawingFigure 4

AI summary

An HVAC system includes a first and a second electric motor. A load manager is coupled to the first electric motor. The load manager is configured to prevent the first electric motor from operating simultaneously with said second electric motor.