Discharge Pump Phase Control for Air-Water Motor Instability
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Solution Overview
Problem
Discharge pumps actuated by permanent magnet synchronous electric motors in household appliances face inefficiencies in energy use and noise, instability, and mechanical starting issues, particularly in air-water conditions, without allowing optimal energy efficiency and stability.
Innovation Solution
A method controlling the synchronous electric motor by phase control, where the firing angle is feedback-controlled to synchronize the motor's operation, and the motor is switched off temporarily when operating in air-water conditions to optimize energy use, with thresholds calculated based on grid voltage, and restarted according to decreasing or increasing time functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If simple starting and stopping control is used, then production and assembly costs are low, but air-water condition operating states cannot be identified and energy efficiency is poor
Solution Approach 1:
The patent implements feedback control by continuously monitoring the phase shift between the mid-point of the zero current plateau and the zero-crossing point of the counter electromotive force signal. This feedback mechanism enables the control system to identify air-water operating conditions and adjust the firing angle accordingly, optimizing energy efficiency while maintaining cost-effective control electronics
Solution Approach 2:
The patent changes the operating parameters of the motor by dynamically adjusting the firing angle based on detected phase shifts. When air-water conditions are detected through phase shift analysis, the system modifies the motor's operating parameters to prevent inefficient operation, thereby improving energy efficiency without requiring complex control hardware
2Ease of manufacture
If simple starting and stopping control is used, then production and assembly costs are low, but noise levels are very high in air-water conditions
Solution Approach 1:
The feedback control system monitors phase shift characteristics to detect air-water operating conditions that generate excessive noise. By identifying these conditions through electrical signal analysis rather than acoustic sensors, the system can take preventive action to reduce noise generation while maintaining simple and cost-effective control electronics
Solution Approach 2:
The system takes preliminary anti-action by detecting air-water conditions through phase shift monitoring before excessive noise is generated. The control system adjusts the firing angle proactively to prevent the motor from operating in noisy air-water conditions, rather than reacting to noise after it occurs
3Use of energy by moving object
If phase control with feedback is implemented, then energy efficiency is optimized, but device complexity increases
Solution Approach 1:
The patent implements feedback control using existing control electronics to monitor the phase shift between current and voltage signals. The feedback mechanism utilizes standard microcontroller capabilities and basic signal processing to adjust the firing angle, optimizing energy efficiency without requiring complex additional hardware or sophisticated control algorithms
Solution Approach 2:
The patent replaces mechanical sensing methods with electrical signal analysis. Instead of using mechanical sensors or complex physical measurement systems to detect operating conditions, the system uses electrical signal processing of the motor's counter electromotive force and current characteristics, thereby reducing device complexity while achieving precise control
4Reliability
If maximum firing angle threshold is exceeded, then motor protection is achieved, but operational interruptions occur
Solution Approach 1:
The system takes preliminary anti-action by monitoring the firing angle and detecting when it approaches the maximum threshold before damage occurs. By identifying air-water conditions through phase shift analysis and taking preventive action (switching off the motor), the system protects the motor from overheating and damage while minimizing operational interruptions through calculated restart timing
Solution Approach 2:
The patent implements periodic action by switching the motor off for a calculated temporary period when air-water conditions are detected, then restarting it after the protective interval. This periodic on-off operation protects the motor from continuous damage while restoring functionality, with the off-time optimized to balance protection and productivity
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 method enhances energy efficiency, reduces noise, and stabilizes the motor's operation, ensuring optimal performance and preventing overheating, while maintaining cost-effectiveness and reliability.
Implementation Method 1
the zero-crossing point of a counter electromotive force signal relative to the same step
Data Source
AI summary
A method for controlling a discharge pump of a household appliance, including starting a synchronous electric motor that actuates said discharge pump until the synchronism condition is reached, and driving said synchronous electric motor at a steady state through phase control by varying the firing angle (α). In driving said synchronous motor at steady state through phase control, said firing angle (α) is feedback controlled to cancel the phase difference between the mid-point of a zero current plateau of a function of the phase current fed to the electric motor and the zero-crossing point of a counter electromotive force signal (fcem) relative to the same phase. In feedback controlling the firing angle (α), the synchronous electric motor is switched off if the required firing angle (α) exceeds a maximum threshold (αlim), which may result from the operation of the discharge pump in air-water conditions.