Inverter and refrigerator including inverter
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Solution Overview
Problem
Conventional two-phase modulation in inverters increases carrier frequency harmonic noise, making it difficult to transition from three-phase to two-phase modulation in quiet devices like refrigerators, and results in reduced power saving due to higher carrier frequency requirements, while existing harmonic suppression techniques have inferior current harmonics and noise performance compared to triangular wave modulation.
Innovation Solution
An inverter with a three-phase bridge configuration and a processor that alternately repeats two distinct periods in a two-phase modulation method, turning on/off switching elements at carrier wave crests/troughs to reduce line voltage harmonic components to levels equivalent to three-phase modulation, thereby improving power savings and quietness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional two-phase modulation is used to reduce switching loss, then power consumption decreases, but carrier frequency harmonic noise increases
Solution Approach 1:
The patent applies periodic action by alternating between two distinct modulation periods (first period and second period) with different switching element configurations. This periodic alternation allows the system to maintain two-phase modulation for power savings while controlling harmonic noise through structured switching patterns at carrier wave crests and troughs
Solution Approach 2:
The patent changes the switching state parameters of the inverter bridge by maintaining different switching elements in on-state during first and second periods. This parameter change enables the system to achieve equivalent noise performance to three-phase modulation while maintaining the power savings of two-phase modulation
2Object-generated harmful factors
If carrier frequency is increased to ensure quietness in two-phase modulation, then noise performance improves, but power saving effect decreases
Solution Approach 1:
The patent changes the switching control parameters by turning on/off all switching elements at specific carrier wave points (crests in first period, troughs in second period). This parameter change allows the system to maintain lower carrier frequencies while achieving equivalent noise performance to three-phase modulation, thereby preserving power saving benefits
3Loss of energy
If two-phase modulation is used instead of three-phase modulation, then switching loss reduces, but line voltage harmonic components increase
Solution Approach 1:
The patent uses periodic alternation between first and second periods with different switching element on-states. This periodic structure controls the generation of line voltage harmonics by ensuring that harmonic-producing switching events occur at controlled intervals at carrier wave crests and troughs, reducing overall harmonic content
Solution Approach 2:
The patent changes the switching state parameters by maintaining different combinations of switching elements in on-state during first and second periods. This parameter variation reduces line voltage harmonic components to levels equivalent to three-phase modulation while maintaining two-phase modulation power savings
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 solution effectively reduces carrier frequency harmonic noise and improves power savings and quietness by maintaining equivalent noise performance to three-phase modulation while reducing switching losses.
Implementation Method 1
convert input direct current (DC) power into three-phase alternating current (AC) power
Data Source
AI summary
Provided is an inverter for reducing electric power consumption and noise. The inverter comprises: a driving unit including three switching elements included in an upper arm and connected in a three-phase bridge configuration and three switching elements included in a lower arm and connected in a three-phase bridge configuration, and converting input direct current power into three-phase alternating current power and then outputting the alternating current power to a three-phase load; and at least one processor for maintaining one of the three switching elements, which are included in the upper arm, in an on-state in a first period, maintaining one of the three switching elements, which are included in the lower arm, in an on-state in a second period, and driving the driving unit in a two-phase modulation method by alternately repeating the first period and the second period, wherein the at least one processor turns on all of the three switching elements at a crest of a carrier wave in the first period, and the at least one processor turns off all of the three switching elements at a crest of a carrier wave in the second period.