Electric compressor
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Solution Overview
Problem
Existing electric compressors face difficulties in accurately estimating the dryness of refrigerant due to the presence of liquid refrigerant, which can lead to compressor failure.
Innovation Solution
An electric compressor equipped with a controller that utilizes suction and discharge pressure sensors, along with a motor information detector, to estimate refrigerant dryness based on a stored map correlating suction pressure, discharge pressure, rotational speed, and power consumption, thereby controlling the electric motor to prevent liquid refrigerant compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature-based dryness estimation is used, then the estimation method is simple, but it becomes inaccurate when liquid refrigerant is present
Solution Approach 1:
The patent changes the estimation parameters from temperature-based to power consumption and rotational speed-based parameters. The controller estimates dryness by detecting power consumption and rotational speed of the motor, then referencing a pre-stored map that correlates these parameters with dryness values. This approach maintains estimation simplicity while achieving accuracy even when liquid refrigerant is present, as power consumption characteristics differ between gas and liquid compression.
2Reliability
If temperature-based dryness estimation is used, then the system structure is simple, but compressor failure risk increases due to inaccurate estimation
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors power consumption and rotational speed, estimates dryness using the stored map, and uses this information to control compressor operation. This feedback loop enables the system to detect liquid refrigerant conditions and adjust operation accordingly, significantly improving compressor reliability while adding only minimal system complexity through software-based control logic.
3Measurement precision
If temperature sensors are used for dryness estimation, then the measurement is straightforward, but the estimation fails when liquid refrigerant is compressed
Solution Approach 1:
The patent replaces the thermal measurement approach (temperature sensors) with a mechanical/electrical measurement approach (power consumption and rotational speed sensors). Since power consumption characteristics during compression differ between gas and liquid states, this substitution enables accurate dryness estimation without relying on temperature, which becomes unreliable when liquid refrigerant is present. The detection difficulty is reduced as power and speed are easily measurable electrical parameters.
Data Source
AI summary
An electric compressor includes: a compression part; an electric motor; and a controller. The controller includes a motor information detector for detecting a rotational speed and a power consumption of the electric motor, and is connected to a suction pressure sensor for detecting a suction pressure of a refrigerant and a discharge pressure sensor for detecting a discharge pressure of the refrigerant. The controller further includes: a memory for storing a map; an estimator; and an operation controller. The map indicates a correspondence between the suction pressure, the discharge pressure, the rotational speed, the power consumption, and dryness of the refrigerant to be drawn into the compression part. The estimator estimates the dryness of the refrigerant based on the map using the rotational speed and the power consumption, the suction pressure, and the discharge pressure. The operation controller controls an operation of the electric motor according to the dryness.