Air conditioner
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Solution Overview
Problem
Existing air conditioners generate significant harmonic components in their input currents, which exceed the limits specified in IEC 61000-3-2, particularly in the integer-order components from the second to 40th orders, leading to potential electromagnetic interference and inefficiencies.
Innovation Solution
The air conditioner is designed with an indoor and outdoor unit, each equipped with a converter circuit, inverter circuit, and a capacitor, where the indoor-unit power line and outdoor-unit power line branch from a common power line. The indoor and outdoor units include control units that manage the input currents to minimize harmonic components by adjusting the operation of the inverter circuits, ensuring the total harmonic components in the combined current remain below specified limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional converter circuits and inverter circuits are used in air conditioners, then power conversion functionality is achieved, but significant harmonic components are generated in the input current
Solution Approach 1:
The patent applies active harmonic compensation by generating compensation currents that are equal in magnitude but opposite in phase to the harmonic components. The converter circuit intentionally generates compensation harmonics (2nd to 40th orders) that cancel out the harmful harmonic components, converting the harmful effect into a beneficial cancellation effect that reduces total harmonic distortion to comply with IEC 61000-3-2 standards
2Productivity
If multiple air conditioners operate simultaneously on a common power line, then power supply coverage is improved, but harmonic components accumulate and exceed standard limits
Solution Approach 1:
The patent employs feedback control where the control unit continuously monitors the input current to detect harmonic components (2nd to 40th orders). Based on this feedback, the control unit dynamically adjusts the converter circuit to generate appropriate compensation currents that cancel the detected harmonics, enabling multiple units to operate simultaneously without harmonic accumulation exceeding IEC 61000-3-2 limits
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 total harmonic components in the combined input current are reduced, aligning with IEC 61000-3-2 standards, thereby minimizing electromagnetic interference and improving operational efficiency.
Implementation Method 1
a converter circuit configured to rectify AC power delivered from the AC power source to a DC power
Implementation Method 2
an inverter circuit configured to convert the DC power output by the converter circuit into AC power
Implementation Method 3
a capacitor connected between input nodes of the inverter circuit
Data Source
AI summary
An air conditioner includes an indoor unit, outdoor unit, indoor unit power line, and outdoor unit power line. The power lines branch from a common power line. Each of the indoor and outdoor units includes a converter circuit, an inverter circuit, and a capacitor. A total of effective values of integer-order components from second to 40th orders in a total current, which is obtained by adding up an indoor-unit input current and an outdoor-unit input current and which flows through the common power line, is less than a sum of a total of effective values of integer-order components from the second to 40th orders included in the indoor-unit input current that flows through the indoor-unit power line and a total of effective values of integer-order components from the second to 40th orders included in the outdoor-unit input current that flows through the outdoor-unit power line.