Washing Machine Inverter PWM With Variable Carrier Frequency
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Solution Overview
Problem
Existing drum type washing machines experience significant energy loss and increased manufacturing costs due to the inefficiency of the inverter in the direct drive method, particularly during the toggle periods of the inverter, which necessitates larger inverter capacity and additional heat management components.
Innovation Solution
A driving device for a washing machine that employs a variable frequency carrier wave in the pulse width modulation (PWM) to control the inverter, reducing power loss during toggle periods and allowing for a smaller inverter capacity by adjusting the carrier wave frequency based on motor rotation speed and load, thereby optimizing inverter efficiency and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inverter capacity is increased to compensate for efficiency losses, then motor control reliability is improved, but manufacturing cost increases
Solution Approach 1:
By changing the carrier wave frequency parameter dynamically, the patent improves inverter efficiency without requiring increased inverter capacity. This allows the system to maintain reliable motor control with a smaller, more cost-effective inverter design.
2Device complexity
If a fixed frequency carrier wave is used in PWM, then inverter control is simplified, but power loss during toggle periods increases
Solution Approach 1:
The patent transitions from a static fixed-frequency carrier wave to a dynamic variable-frequency carrier wave that adapts to motor operating conditions. This dynamic approach reduces toggle period power loss while maintaining manageable control complexity through systematic frequency adjustment based on rotation speed and load.
3Reliability
If heat management components are added to handle inverter heat generation, then inverter reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent converts the harmful effect of toggle period power loss into a benefit by using variable frequency control to minimize these losses in the first place. This preventive approach reduces heat generation at the source, eliminating or reducing the need for additional heat management components.
Solution Approach 2:
By dynamically adjusting the carrier wave frequency parameter, the system reduces power loss and heat generation in the inverter, thereby improving reliability without requiring additional cooling systems or heat management hardware.
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 reduces power loss and heat generation within the inverter, allowing for a smaller inverter capacity and lower manufacturing costs while maintaining precise motor control and minimizing noise and vibration, thus enhancing the overall efficiency and cost-effectiveness of the washing machine.
Implementation Method 1
an inverter driver configured to compare a control signal with a carrier wave, wherein the inverter driver drives the inverter by pulse width modulation
Implementation Method 2
a variable motor configured to apply a driving force to a drum of the washing machine
Data Source
AI summary
A driving device and a method of driving a washing machine is disclosed. The efficiency of the motor of the washing machine is enhanced and the capacity of an inverter is reduced thereby reducing manufacturing costs. The driving device includes a variable motor, of which the rotational speed varies to apply a driving force to a drum to rotate, an inverter to convert a direct current voltage into an alternating current voltage and to vary a voltage applied to the variable motor, and an inverter driver to compare a control signal with a carrier to drive the inverter by pulse width modulation. A frequency of the carrier wave is varied for the pulse width modulation.