Electrochromic Window PWM Control for IGU-Integrated Power Delivery
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Solution Overview
Problem
Existing technologies face challenges in efficiently integrating and controlling optically-switchable devices like electrochromic windows, particularly in terms of organizing, powering, and delivering power to these devices for optimal energy efficiency and aesthetic purposes.
Innovation Solution
A window controller that generates pulse-width-modulated signals to drive optically-switchable devices, utilizing a command-voltage generator and pulse-width-modulated-signal generator to adjust duty cycles and voltages across conductive electrode layers, integrated within a seal of an insulated glass unit (IGU), and can communicate with building management systems for holistic energy control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If electrochromic windows are integrated into buildings for energy efficiency and aesthetic control, then optical properties can be adjusted, but power delivery and control organization become complex
Solution Approach 1:
The patent divides the control system into modular components: a controller unit integrated within the IGU seal that generates command voltage signals, and a driver circuit that converts these signals into appropriate voltage levels for the electrochromic device. This segmentation simplifies the overall system architecture by localizing control functions within the window assembly itself, reducing external complexity.
Solution Approach 2:
The controller acts as an intermediary device between the building management system and the electrochromic window. It receives command signals, processes them through pulse-width modulation, and delivers the appropriate voltage to the electrochromic device. This intermediary function simplifies integration by providing a standardized interface that handles the complexity of power conversion and control signaling.
2Use of energy by moving object
If pulse-width-modulated signals are used to drive optically-switchable devices, then energy efficiency is improved, but signal generation and control precision requirements increase
Solution Approach 1:
The controller employs pulse-width modulation (PWM) to drive the electrochromic device, using periodic square-wave signals with varying duty cycles to control the optical state. This periodic action allows efficient energy delivery by applying voltage only when needed to maintain the desired state, reducing overall power consumption while simplifying the drive circuitry compared to analog control methods.
Solution Approach 2:
The system controls the electrochromic device by changing the duty cycle parameter of the PWM signal rather than varying voltage amplitude continuously. This parameter change approach simplifies the signal generation requirements, as it uses fixed-voltage square waves with adjustable timing characteristics, reducing the complexity of voltage regulation circuits while maintaining precise control.
3Ease of operation
If the controller is integrated within the IGU seal, then installation and control are simplified, but space within the seal is limited
Solution Approach 1:
The controller is nested within the existing IGU seal structure, utilizing the available space efficiently. The controller unit, driver circuit, and associated components are compactly arranged within the seal's internal volume, which already contains the electrochromic device and interlayer materials. This nesting approach allows integration of control functions without requiring additional external space.
Solution Approach 2:
The controller employs printed circuit boards and thin-film electronics to minimize component volume. The driver circuit and signal processing elements are implemented on flexible or rigid-flex PCBs that can conform to the available space within the seal, allowing integration of sufficient processing and power conversion capabilities without exceeding the limited volume budget of the IGU seal.
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 efficient control of electrochromic windows, optimizing energy usage and aesthetics by adjusting optical properties based on feedback and input from various building systems, enhancing energy efficiency and comfort.
Implementation Method 1
Electrochromism is a phenomenon in which a material exhibits a reversible electrochemically-mediated change in one or more optical properties when stimulated to a different electronic state. For example, the electrochromic material can be stimulated by an applied voltage.
Data Source
AI summary
This disclosure provides a window controller that includes a command-voltage generator that generates a command voltage signal, and a pulse-width-modulated-signal generator that generates a pulse-width-modulated signal based on the command voltage signal. The pulse-width-modulated signal drives an optically-switchable device. The pulse-width-modulated signal comprises a first power component having a first duty cycle and a second power component having a second duty cycle. The first component delivers a first pulse during each active portion of the first duty cycle, and the second component delivers a second pulse during each active portion of the second duty cycle. The first pulses are applied to a first conductive layer and the second pulses are applied to a second conductive layer. The relative durations of the active portions and the relative durations of the first and second pulses are adjusted to result in a change in an effective DC voltage applied across the optically-switchable device.