Thermal regulation of drive in air conditioning systems
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Solution Overview
Problem
Air conditioning systems with electrically driven components often shut down unnecessarily due to temperature thresholds exceeded by power switching devices, leading to inefficient operation and potential damage.
Innovation Solution
An air conditioning system with a temperature sensor and controller that monitors the temperature of power switching devices in the converter and inverter, reducing switching frequency using pulse width modulation (PWM) and hybrid PWM (HPWM) control, and adjusting compressor load to prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the air conditioning system shuts down when the temperature of power switching devices exceeds the threshold, then the power switching devices are protected from damage, but the system experiences unnecessary shutdowns and loss of productivity
Solution Approach 1:
The patent applies dynamics by transitioning from a static temperature threshold shutdown approach to a dynamic temperature management approach. The system continuously adjusts the switching frequency of power electronic devices based on real-time temperature monitoring, allowing the operating parameters to change dynamically while maintaining safe temperature levels. This enables the system to operate continuously without unnecessary shutdowns while still protecting the power switching devices.
2Temperature
If the switching frequency of power switching devices is reduced, then the temperature of power switching devices is controlled, but the system efficiency and cooling performance deteriorate
Solution Approach 1:
The patent implements periodic action through pulsed operation modes where the power switching devices operate at high switching frequency during periods when temperature is within acceptable ranges, and reduce to lower switching frequency or enter idle periods when temperature approaches thresholds. This periodic modulation of switching frequency allows the system to maintain average temperature control while preserving overall system efficiency and cooling performance.
Solution Approach 2:
The system dynamically changes the switching frequency parameter based on temperature conditions. When temperature is low, the switching frequency operates at optimal high values for efficiency. When temperature approaches the threshold, the switching frequency is reduced to control heat generation. This parameter adaptation allows the system to optimize between temperature control and efficiency at different operating conditions.
3Productivity
If the air conditioning system operates continuously without shutdown, then productivity is maintained, but the temperature of power switching devices may exceed safe thresholds causing damage
Solution Approach 1:
The patent implements feedback control by continuously monitoring the temperature of power switching devices and using this information to adjust the switching frequency in real-time. The temperature sensor provides feedback to the controller, which then modulates the switching frequency to maintain temperature within safe operating limits. This closed-loop feedback system enables continuous operation while reliably protecting the power switching devices from overheating.
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
Prevents unnecessary shutdowns by effectively managing the temperature of power switching devices, reducing the risk of damage and maintaining system efficiency.
Implementation Method 1
a temperature sensor configured to sense a temperature in at least one of the converter and the inverter
Implementation Method 2
A power switching device may be damaged if its temperature exceeds a threshold. To avoid damage to the power switching devices, the air conditioning system is shut down in the event the temperature of a power switching device exceeds the threshold.
Data Source
AI summary
An air conditioning system includes a compressor including a motor, a condenser, and an evaporator; a drive including converter and an inverter, the converter and the inverter including power switching devices; a temperature sensor configured to sense a temperature in at least one of the converter and the inverter; a controller configured to communicate with the temperature sensor, the controller configured to provide a control signal to the inverter, the controller configured to execute: monitor the temperature; compare the temperature to a threshold; when the temperature exceeds the threshold, executing an operation to reduce a switching frequency of the power switching devices in the inverter.