Inverter controller, method of operation thereof and field-installable retrofit kit incorporating the same
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Solution Overview
Problem
HVAC systems lacking direct digital controls (DDCs) face challenges in accommodating multi-speed blower operation without compromising performance or incurring additional costs, especially when complying with regulations that require reduced blower speed, which can lead to overheating and ventilation code violations.
Innovation Solution
An inverter controller and retrofit kit that employ cascading relay logic or supplementary DDCs to manage blower speeds, allowing for multi-speed operation without rewiring, and include a field-configurable blower speed selector to automatically adjust speeds based on thermostat signals, ensuring appropriate airflow and energy savings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If blower speed is reduced to comply with two-speed regulations, then energy consumption is reduced, but ventilation adequacy deteriorates and may violate building ventilation codes
Solution Approach 1:
The patent implements dynamic blower speed control that adjusts blower operation based on real-time system conditions. The controller monitors cooling load, temperature differentials, and operational mode to dynamically select appropriate blower speeds, transitioning from static high-speed operation to adaptive multi-speed operation that optimizes both energy efficiency and ventilation requirements
Solution Approach 2:
The system changes the operational parameters of the blower motor by implementing multi-speed operation with distinct speed settings for different modes. The controller adjusts blower speed parameters based on operational context - using high speed for heating and emergency conditions, and selectively applying low speed only during cooling operation when ventilation requirements are naturally satisfied by the cooling process itself
2Loss of energy
If blower speed is reduced during cooling operation, then energy consumption is reduced, but heat exchanger airflow is insufficient causing overheating and system shutdowns
Solution Approach 1:
The controller implements dynamic monitoring of heat exchanger temperatures and cooling load conditions. When cooling demand increases or temperature differentials indicate insufficient heat exchange, the system dynamically transitions from low-speed to high-speed blower operation, ensuring heat exchanger temperatures remain within safe operating ranges while maintaining energy efficiency during light-load conditions
3Adaptability or versatility
If existing HVAC systems without DDCs are modified to accommodate multi-speed operation, then compliance with two-speed regulations is achieved, but system complexity and modification cost increase
Solution Approach 1:
The patent introduces an intermediary inverter controller that acts as a bridge between simple existing HVAC systems and the requirements for multi-speed operation. This controller receives standard thermostat signals and translates them into appropriate inverter drive commands, enabling multi-speed blower operation without requiring complex DDC system integration or extensive modifications to the existing HVAC control architecture
Solution Approach 2:
The inverter controller replicates the functionality of complex DDC systems by implementing embedded control logic that mimics sophisticated temperature and load management algorithms. This allows existing simple systems to achieve DDC-level compliance and control capabilities through the inverter controller's copied intelligence, without actually installing expensive DDC hardware
4Adaptability or versatility
If new HVAC systems are designed from the ground up with DDCs to accommodate multi-speed operation, then operational flexibility and compliance are improved, but manufacturing cost and installation complexity increase
Solution Approach 1:
The patent segments the control functionality into a separate inverter controller module that can be independently manufactured and installed. This modular approach allows the multi-speed control capability to be offered as an add-on component rather than requiring complete system redesign, enabling manufacturers to produce compliant systems through modular assembly rather than integrated DDC system manufacturing
Solution Approach 2:
The inverter controller is designed as a universal control solution that can be applied to various HVAC system configurations and thermostat types. It provides multi-functional capability by handling both simple on/off control and sophisticated multi-speed inverter control through a single device, making it suitable for retrofit applications across different system architectures without requiring custom-designed control systems for each application
Data Source
AI summary
An inverter controller, a method of operating a controller and a field-installable kit. In one embodiment, the controller includes: (1) a thermostat interface configured to receive conventional thermostat signals providing for a ventilation mode, first- and second-stage cooling modes and at least one heating mode and provide relay control signals for an inverter forward start relay, first- and second-stage cooling speed select relays and at least one heating relay and (2) an inverter controller coupled to the thermostat interface and configured to receive the relay control signals and provide an inverter forward start signal, an inverter high speed set, an inverter medium speed set and an inverter ventilation speed set.