Control circuit and dishwasher comprising the same
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Solution Overview
Problem
Existing methods for suppressing electromagnetic interference (EMI) in dishwashers, particularly in switched mode power supply (SMPS) ICs and motors, are inefficient due to increased cost and volume, and fail to effectively cancel noise at the primary resonant frequency of the motor.
Innovation Solution
A control circuit that includes a converter, an inverter, and a second core wound with a specific number of turns determined by the motor's impedance, which passes the driving power lines through its center, effectively cancelling noise at the primary resonant frequency and reducing product volume and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a harness core is wound by a large number of turns to achieve large inductance for EMI suppression, then EMI suppression capability is improved, but product cost and core volume increase
Solution Approach 1:
The patent changes the key parameter from number of turns to core material permeability and geometric configuration. By using high permeability material and optimizing core geometry, the patent achieves sufficient inductance with fewer turns, thereby reducing core volume while maintaining EMI suppression capability
Solution Approach 2:
Instead of increasing the number of turns to increase inductance, the patent inverts the approach by using high permeability core material to achieve the same inductance effect with fewer turns, thus solving the volume-cost problem
2Object-affected harmful factors
If a harness core is wound by a large number of turns to achieve large inductance for EMI suppression, then EMI suppression capability is improved, but manufacturing cost increases
Solution Approach 1:
The patent changes the key parameter from number of turns to core material permeability and geometric configuration. By using high permeability material and optimizing core geometry, the patent achieves sufficient inductance with fewer turns, thereby reducing manufacturing cost while maintaining EMI suppression capability
Solution Approach 2:
The patent employs a core design that uses readily available high permeability material with optimized geometry, creating a cost-effective solution that achieves the required EMI suppression without requiring expensive multi-turn windings
3Object-affected harmful factors
If conventional EMI suppression methods are used in SMPS IC and motor, then some EMI is suppressed, but noise emitted to outside of the motor cannot be further suppressed
Solution Approach 1:
The patent introduces a common mode choke as an intermediary component between the motor and the external environment. This choke specifically targets and suppresses common mode noise currents that radiate externally, complementing the internal EMI suppression measures already in place for the SMPS IC and motor
Solution Approach 2:
The patent segments the EMI suppression function into two parts: internal suppression (using RCD snubber for SMPS IC and harness core for motor) and external suppression (using common mode choke for radiated noise). This segmentation allows each component to specialize in its specific suppression task, achieving comprehensive EMI control
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 control circuit effectively suppresses EMI and reduces harmonic noise, achieving cost and volume reductions while improving noise cancellation at the primary resonant frequency.
Implementation Method 1
a second core formed by winding a coil by a number of windings determined in correspondence with an impedance of the motor... capable of lowering a level of additionally generated harmonic noise by cancelling noise generated at a primary resonant frequency of a motor
Data Source
Figure 1~2
Figure 3
AI summary
An embodiment relates to a control circuit, which includes a converter configured to convert alternating current (AC) power into direct current (DC) power, an inverter configured to generate driving power of at least one motor using the DC power, and a first core formed by winding a coil by a number of windings determined in correspondence with an impedance of the motor, wherein the number of windings is determined in a manner that an impedance of the first core is inversely proportional to the impedance of the motor, and a driving power line for driving the motor passes through a center of the first core.