Avionic Refrigeration Control With Brushless DC Motor Commutation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional avionic refrigeration systems using AC induction motors face challenges due to their large size, weight, and difficulty in accurate and variable control, particularly in avionic environments where sensor wiring is prone to corruption and electromechanical position sensors are prone to malfunction.
Innovation Solution
A wild frequency avionic refrigeration system utilizing brushless DC motors and sensors, with a power module to convert wild frequency AC input voltage to DC output voltage, and a processing module to output control signals for independently driving the motors, eliminating the need for electromechanical position sensors and improving control accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If AC induction motors are used in conventional avionic refrigeration systems, then the system can be constructed with low cost and rugged components, but the system suffers from large size, excessive weight, and difficulty in accurate and variable control
Solution Approach 1:
The patent replaces AC induction motors with brushless DC motors. This substitution eliminates the need for electromechanical position sensors (Hall Effect sensors) and their associated wiring harnesses, thereby reducing weight while improving control accuracy. The brushless DC motor uses electronic commutation controlled by a microprocessor, providing precise speed and position control without mechanical sensors.
2Measurement precision
If Hall Effect sensors are used for feedback control of AC induction motors, then position data can be obtained, but the sensor wiring is prone to corruption due to harness crosstalk and electromagnetic interference in avionic environments
Solution Approach 1:
The patent eliminates Hall Effect sensors and their wiring harnesses by using brushless DC motors with electronic commutation. The motor controller uses back-EMF sensing or Hall sensors integrated within the motor assembly (not requiring external wiring) to determine rotor position, thereby eliminating the vulnerable external wiring harness that is susceptible to EMI and crosstalk in avionic environments.
Solution Approach 2:
The patent introduces a microprocessor-based motor controller as an intermediary between the power source and the motor. This controller processes sensor data and generates commutation signals, providing isolated digital communication that is resistant to EMI. The controller acts as a mediator that converts analog sensor signals into robust digital control signals for the power inverter stage.
3Measurement precision
If Hall Effect sensors are used in sealed compressors containing refrigerant and oil, then position feedback can be obtained, but the sensors are prone to malfunction or failure over time due to wear and tear
Solution Approach 1:
The patent replaces Hall Effect sensors with brushless DC motor technology that uses electronic commutation. The rotor position is determined through back-EMF sensing or integrated Hall sensors that are hermetically sealed within the motor assembly, eliminating exposure to refrigerant and oil. This substitution provides wear-free operation with no moving parts in the sensing mechanism, thereby dramatically improving reliability in sealed compressor environments.
4Device complexity
If AC induction motors are used with electromechanical position sensors, then the system can operate with simple construction, but the system lacks accurate and variable control capability
Solution Approach 1:
The patent replaces AC induction motors with brushless DC motors controlled by a microprocessor-based system. The motor controller receives position and speed feedback, processes the signals through PWM modulation, and generates precise commutation signals. This electronic control system provides accurate speed and position control with programmable logic, enabling variable operation modes and precise temperature control while maintaining manageable system complexity through integrated control circuits.
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 system provides reliable and accurate control of the refrigeration unit, reducing the risk of sensor malfunctions and interference, and enabling efficient operation in avionic environments with improved motor control and reduced maintenance needs.
Implementation Method 1
a power module configured to convert a wild frequency AC input voltage to at least one DC output voltage
Implementation Method 2
a brushless DC compressor motor, a brushless DC condenser motor, a brushless DC evaporator motor
Data Source
AI summary
A wild frequency avionic refrigeration system and a controller therefore are provided. One embodiment of the refrigeration system includes: a refrigeration LRU including a vapor cycle system with a brushless DC compressor motor, a brushless DC condenser motor, a brushless DC evaporator motor and a plurality of sensors configured to output operating parameter data relative to the vapor cycle system; a power module configured to convert a wild frequency AC input voltage to at least one DC output voltage; a motor control module in communication with the brushless DC compressor, condenser and evaporator motors; and a processing module in communication with the plurality of sensors and the motor control module, wherein the processing module, according to the operating parameter data, outputs control signals to the motor control module for independently driving the brushless DC compressor, condenser and evaporator motors.