Adapter Module for Triac-Controlled PSC Motor Replacement
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Solution Overview
Problem
Triac-controlled permanent split capacitor (PSC) motors have limitations such as low efficiency, noise, and mechanical inefficiencies, making it desirable to replace them with permanent magnet AC motors, but existing technologies lack a method to directly control the speed of permanent magnet AC motors using triac-controlled AC voltage signals.
Innovation Solution
An adapter module that generates a motor speed command for a permanent magnet AC motor based on the delay angle of a triac, while minimizing the temperature increase of the simulated load resistor by reducing triac conducting time, using a system comprising a simulated load, zero-crossing detector, turn-on instance detector, and speed command generator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a permanent magnet AC motor replaces a triac-controlled PSC motor, then efficiency and mechanical properties improve, but compatibility with existing triac control systems is lost
Solution Approach 1:
An adapter module is introduced as an intermediary between the triac control system and the permanent magnet AC motor. The adapter receives the triac's AC voltage signal with varying conduction angles and converts it into appropriate control signals for the motor controller, enabling compatibility without direct connection. This mediator preserves the benefits of both the triac control system and the permanent magnet motor.
Solution Approach 2:
The patent replaces the direct electrical connection and control mechanism (triac to motor) with an electronic substitution system. The adapter module uses electronic circuitry to detect zero-crossing points, measure conduction angles, and generate digital control signals, substituting the direct analog control method with a digital electronic control system that bridges the incompatibility between triac and permanent magnet motor.
2Speed
If triac conduction angle is used to control motor speed, then speed adjustment is achieved, but heat generation in simulated load resistor increases
Solution Approach 1:
The system performs preliminary detection of the zero-crossing point and conduction angle from the triac's AC voltage signal before generating the motor speed command. By measuring these parameters in advance and converting them to a digital speed command, the system avoids the need for the simulated load resistor to continuously handle high power, reducing heat generation while preserving speed control information.
Solution Approach 2:
The adapter module acts as an intermediary that extracts speed control information from the triac's voltage signal without requiring the simulated load resistor to dissipate excessive power. The module detects electrical parameters (zero-crossing, conduction angle) and converts them into motor control commands, mediating between the triac control signal and the motor drive requirements.
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 permanent magnet AC motor speed, replacing triac-controlled PSC motors, with reduced heat generation and improved efficiency by minimizing triac conducting time, allowing for accurate speed control and increased reliability in evaporative coolers and similar applications.
Implementation Method 1
The zero-crossing detector may detect a zero-crossing point of an AC voltage signal from a wall outlet
Implementation Method 2
minimizing the temperature increase of the simulated load resistor through minimizing the triac conducting time
Data Source
AI summary
A system and method for controlling a speed of a permanent magnet AC motor (38) based on a delay angle of a triac-controlled AC voltage signal (66) from a triac (34). A simulated load (54) connected to the triac (34) enables a load current and creates the signal (66). A first detector (48) detects a zero-crossing point of the AC voltage signal, and a second detector (50) detects a subsequent turn-on instance of the triac (34). A speed command generator (52) measures an interval between the zero-crossing point and the subsequent turn-on instance, and converts the delay angle to a speed command for controlling the speed of the motor (38). The simulated load (54) may include resistors (70) having a resistance which causes the load current to be below a holding current rating of the triac (34), thereby causing the triac (34) to turn off after the interval has been measured.