Braking control method for variable-frequency motor of washing machine and washing machine
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Washing machines lack effective brake control during the dewatering process, leading to prolonged motor braking time, noise generation due to abrupt belt and pulley friction, and reduced belt service life.
Innovation Solution
A brake control method for variable-frequency motors that gradually decreases motor speed with hierarchical decelerations, switching to increasingly greater decelerations until the motor reaches 0 rpm, ensuring smooth deceleration and preventing excessive noise and belt wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If direct brake method is used to quickly reduce motor speed to 0 rpm, then braking time is reduced, but large friction between belt and motor pulley generates large noise and reduces belt service life
Solution Approach 1:
The braking process is segmented into multiple deceleration stages with different deceleration rates. The method divides the speed reduction process into at least two stages: a first deceleration stage with a first deceleration rate, and a second deceleration stage with a second deceleration rate that is greater than the first. This segmentation allows the system to achieve quick braking overall while using gentler deceleration at critical moments to reduce noise and belt wear.
Solution Approach 2:
The deceleration rate is made dynamic rather than constant. The control method adjusts the deceleration rate based on the current motor speed, applying a smaller deceleration rate at higher speeds and progressively increasing the deceleration rate as speed decreases. This dynamic adjustment optimizes the balance between braking speed and minimizing harmful effects like noise and belt friction.
2Object-affected harmful factors
If motor speed decreases freely without brake function, then no friction noise is generated, but braking time becomes relatively long due to inertia
Solution Approach 1:
The control method implements dynamic deceleration control where the deceleration rate varies with motor speed. By applying appropriately controlled deceleration at different speed levels, the system achieves significantly reduced braking time compared to free deceleration, while maintaining acceptable noise levels through intelligent deceleration management.
Solution Approach 2:
The braking process uses periodic adjustment of deceleration rates through multiple stages. The control system periodically switches between different deceleration rates based on speed thresholds, creating a structured deceleration pattern that balances speed reduction efficiency with noise control.
3Reliability
If door lock is abnormally opened during high-speed dewatering and motor cannot decelerate, then safety risk increases, but if door remains locked until safe speed is reached, then user convenience decreases
Solution Approach 1:
The control method prepares for potential safety issues by implementing a structured multi-stage deceleration plan in advance. If abnormal door opening is detected, the system can immediately execute the pre-planned deceleration stages, ensuring rapid and controlled speed reduction to a safe level, thereby maintaining both safety and user convenience.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A brake control method for a variable-frequency motor of a washing machine, and a washing machine are provided. The washing machine includes a computer controller, a variable-frequency board and a motor, wherein after high-speed dewatering of the washing machine, a CPU on the computer controller transmits a brake command to the variable-frequency board, and after receiving the brake command, a CPU on the variable-frequency board drives the motor to operate. The brake control method includes: after high-speed dewatering of the washing machine, controlling a motor rotating speed to gradually decrease with decelerations in hierarchical increments, so that the motor can decelerate smoothly after high-speed dewatering of the washing machine, thus ensuring the motor brakes in specified time, and also avoiding generating a large noise.