Load Control Device Power Supply for Two-Wire Systems
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Solution Overview
Problem
Existing load control systems for AC power sources struggle to independently control fan motors and lighting loads located in the same enclosure from a remote location using existing building wiring, which typically only provides a single pair of wires without a neutral connection, limiting independent control and requiring additional wires for independent control.
Innovation Solution
A load control device with a controllably conductive device, energy storage device, and controller that charges the energy storage device when non-conductive and renders the conductive device conductive when charged to a predetermined amount, allowing for independent control of fan motors and lighting loads using a two-wire control system, minimizing voltage drop across the control device, and providing substantially all AC voltage to the loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a two-wire control system is used with existing building wiring, then installation simplicity is improved, but independent control capability deteriorates
Solution Approach 1:
The control device is divided into separate functional modules: a power supply module that charges during non-conductive periods and a control module that operates during conductive periods. This segmentation allows the system to maintain independent control capability while using simple two-wire wiring, as each module performs its function independently during different time intervals.
Solution Approach 2:
The system employs periodic charging of the energy storage device during non-conductive periods, followed by periodic operation during conductive periods. This periodic action enables the control device to accumulate necessary energy and then deliver full power to loads, achieving both installation simplicity and independent control capability through time-based functional separation.
2Ease of operation
If power is continuously supplied to the control device, then control functionality is improved, but voltage drop increases
Solution Approach 1:
The control device operates periodically rather than continuously. The energy storage device is charged during non-conductive periods when the control device is inactive, and then discharged during conductive periods when the control device operates. This periodic operation eliminates continuous power consumption and associated voltage drops while maintaining full control functionality during active periods.
Solution Approach 2:
The system performs preliminary charging of the energy storage device during non-conductive periods before the conductive period begins. This preliminary action ensures that sufficient energy is stored in advance to power the control device at full capability during the conductive period without causing voltage drop, as the charging occurs when the control device is not drawing power.
3Power
If the controllably conductive device remains conductive, then power delivery is improved, but power supply charging capability deteriorates
Solution Approach 1:
The controllably conductive device operates in periodic cycles, remaining conductive only during specific intervals when power delivery is needed. During non-conductive intervals, the energy storage device charges from the power supply. This periodic switching between conductive and non-conductive states enables both adequate power delivery during active periods and effective charging during inactive periods.
Solution Approach 2:
The conductive state of the controllably conductive device is dynamically controlled based on system needs. The device transitions between conductive and non-conductive states to balance power delivery requirements with charging requirements. This dynamic control allows the system to optimize both power delivery capability and charging capability at different times within each operational cycle.
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 independent control of fan motors and lighting loads from a remote location using existing building wiring, minimizing voltage drop and ensuring reliable operation by providing nearly full AC voltage to the loads while deriving minimal power for microcontroller and low-voltage circuitry.
Implementation Method 1
The power supply comprises an energy storage device and is adapted to charge the energy storage device when the controllably conductive device is non-conductive
Data Source
AI summary
A load control device is adapted to be disposed in series with an AC voltage source and an electrical load and is operable to provide substantially all voltage provided by the AC voltage source to the load. The load control device comprises a controllably conductive device, a controller, a zero-crossing detector, and a power supply for generating a substantially DC voltage for powering the controller. The power supply is operable to charge an energy storage device to a predetermined amount of energy each half-cycle. The controller is operable to determine when the power supply has stopped charging from the zero-crossing detector each half-cycle, and to immediately render the controllably conductive device conductive to conduct the full load current. Before the controllably conductive device begins to conduct each half-cycle, only a minimal voltage develops across the power supply to allow the energy storage device to charge.