Microprocessor-Controlled Dimmer Power Supply with Boot-Strap Resistor
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Solution Overview
Problem
Conventional two-wire dimmers face limitations in providing sufficient DC voltage to microprocessors due to the need for semiconductor switches to be non-conductive during charging, restricting maximum light intensity and dimming range, and requiring complex monitoring circuits or ADCs for power supply control.
Innovation Solution
A two-wire load control device with a cat-ear power supply that includes a full-wave bridge rectifier and a boot-strap resistor, allowing the microprocessor to control the charging time and conduction of the semiconductor switch, enabling direct monitoring and control of the power supply without the need for an ADC or complex hardware comparison circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the semiconductor switch is kept non-conductive to allow the power supply to draw sufficient current, then the power supply can charge adequately, but the maximum light intensity and dimming range are restricted
Solution Approach 1:
The patent applies dynamics by making the semiconductor switch controllable rather than fixed in state. The microprocessor dynamically adjusts the conduction timing of the semiconductor switch based on power supply charge level, allowing the system to transition between charging mode (switch non-conductive) and lighting mode (switch conductive) to resolve the contradiction between reliable power supply operation and maximum light intensity
Solution Approach 2:
The patent implements feedback by having the microprocessor monitor the power supply charge level and use this information to control the semiconductor switch timing. The monitoring circuit provides feedback about the charge capacitor voltage, and the microprocessor uses this feedback to adjust the dimmer operation, ensuring the power supply has adequate charging time while maximizing light output when charged
2Measurement precision
If complex monitoring circuits or ADCs are used to control the power supply charging, then the power supply control precision is improved, but the device complexity increases
Solution Approach 1:
The patent uses an intermediary approach by introducing a simple monitoring circuit that detects power supply charge level and communicates this information to the microprocessor through a dedicated input pin. This intermediary monitoring circuit provides sufficient measurement precision for controlling the cat-ear power supply without requiring a full ADC or complex hardware comparison circuits, as the microprocessor handles the control logic in software
Solution Approach 2:
The patent replaces complex hardware-based power supply control mechanisms (such as ADCs or hardware comparison circuits) with a software-based control approach. The microprocessor reads the simple monitoring circuit signal and implements the charging control algorithm in software, substituting mechanical/electronic complexity with programmable logic
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
This solution allows for increased dimming range and higher light intensity while ensuring stable power supply operation, reducing the need for large and costly components and eliminating the requirement for complex monitoring circuits, thus enhancing the efficiency and flexibility of the dimmer.
Implementation Method 1
The power supply includes a bridge rectifier
Implementation Method 2
an energy storage capacitor to store energy from the bridge rectifier
Data Source
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AI summary
A power supply for a two-wire load control device supplies power to a microprocessor, in turn controlling the power supply which comprises an energy storage element, e.g., a capacitor, for producing a DC voltage for powering the microprocessor and also includes a high impedance circuit for allowing the energy storage element to receive energy at a first rate before the DC voltage is produced and the microprocessor is powered. The power supply further comprises a low-impedance circuit, i.e., a resistor in series electrical connection with a controllably conductive device, for allowing the energy storage element to receive energy at a second rate greater than the first rate. After starting up, the microprocessor selectively enables and disables the second energy-receiving circuit by rendering the controllably conductive device conductive and non-conductive, respectively. The microprocessor monitors the power supply and to control the amount of power delivered to an electrical load.