Digital Power Supply Control for Multi-Load Harmonic Reduction
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Solution Overview
Problem
Existing power supplies for high-powered loads, such as electric grills, introduce significant harmonic and flicker interference into the power grid, lacking precise control over multiple loads and efficiency, while prior solutions like variable resistors and bi-metal thermometers offer limited precision and efficiency.
Innovation Solution
A digital power supply system using triacs and a microprocessor to deliver discrete power levels to heating elements, allowing independent control of multiple loads with reduced harmonic and flicker interference, and enabling wireless control and monitoring through a remote device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If variable resistors are used to control power delivery to electric loads, then power control is achieved, but harmonics are introduced onto the electrical system and power efficiency decreases
Solution Approach 1:
The patent replaces variable resistors (mechanical/electrical component) with a microprocessor-based digital control system that uses triacs to switch power delivery. This substitution eliminates the continuous resistance adjustment that generates harmonics, replacing it with precise electronic switching control that delivers power in discrete levels without introducing harmful electromagnetic interference.
Solution Approach 2:
The invention changes the control parameter from continuous resistance adjustment to discrete power level switching. The microprocessor controls triacs to deliver specific power levels (e.g., 0%, 25%, 50%, 75%, 100%) to heating elements, transforming the control mechanism from analog variable resistance to digital discrete switching, thereby eliminating harmonic generation while maintaining power control capability.
2Ease of operation
If variable resistors are used to control power delivery to electric loads, then power control is achieved, but power efficiency decreases due to power burning
Solution Approach 1:
The patent replaces variable resistors (which dissipate power as heat) with a microprocessor-based digital control system using triacs. This substitution eliminates the continuous power dissipation inherent in resistance-based control, replacing it with near-lossless electronic switching that only consumes minimal control power while achieving the same power delivery control.
Solution Approach 2:
The invention changes from continuous resistance adjustment (which burns power proportionally to the square of current times resistance) to discrete power level switching using triacs. This parameter change allows the system to deliver exact power levels without the continuous energy waste associated with resistive control, significantly improving power efficiency.
3Device complexity
If bi-metal thermometers are used to control power delivery, then simple control is achieved, but control precision decreases and response time increases
Solution Approach 1:
The patent replaces bi-metal thermometers (mechanical thermal expansion device) with a microprocessor-based digital control system. This substitution transforms the control mechanism from mechanical to electronic/digital, enabling precise temperature sensing and control while dramatically improving response time. The microprocessor can process temperature data and adjust power delivery instantly, whereas bi-metal devices have inherent mechanical lag.
Solution Approach 2:
The invention implements a feedback control system where the microprocessor continuously monitors temperature sensor data and adjusts triac switching to maintain desired power levels. This closed-loop feedback provides precise control by constantly comparing actual temperature with target temperature and making real-time adjustments, eliminating the open-loop, lag-prone bi-metal thermometer approach.
4Ease of operation
If half-wave control techniques are used to deliver power, then power delivery control is achieved, but power is delivered only in stages rather than continuous range
Solution Approach 1:
The patent implements dynamic power control where the microprocessor can independently adjust each triac's firing angle and duty cycle in real-time. This dynamic control allows continuous variation of power delivery from 0% to 100% for each heating element, replacing the static half-wave control approach. The system can smoothly transition between any power levels by adjusting switching timing, providing adaptability for different cooking requirements.
Solution Approach 2:
The invention segments the power control into independent channels for each heating element, with each controlled by its own triac and microprocessor control logic. This segmentation allows each element to operate at any power level independently, rather than forcing all elements to switch in unison as in half-wave control. The result is continuous, versatile power delivery control for each load.
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
The digital power supply system provides precise control over multiple loads, reduces harmonic and flicker interference, extends the lifespan of heating elements, and complies with regulatory standards by using phase cutting techniques and discrete power delivery.
Implementation Method 1
The microprocessor is configured to deliver discrete power levels to the first and second load by activating and deactivating the first and second triac, respectively
Implementation Method 2
a first and second load connected respectively through a first and second triac to a voltage line
Data Source
AI summary
Provided is an apparatus and method for a digital power supply that can provide independent power control for two or more electrical loads. Some disclosed embodiments provide continuous, variable power and other disclosed embodiments provide discrete power levels. Disclosed embodiments may reduce the magnitude of harmonic currents and/or flicker introduced into a power system. Embodiments include a microprocessor that delivers power to electric loads using phase-controlled AC current. In some embodiments, the microprocessor may calculate a power array corresponding to a requested power for each electric load. Logic is provided for populating the power array in a pattern that reduces the magnitude of harmonic currents and flicker. Portions of the disclosure include a band controller for delivering power to achieve and maintain a desired target temperature, and a wireless controller for controlling temperature from a remote device.