Fan Control Using Initial State Detection for Bus Voltage Stability
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Solution Overview
Problem
Variable frequency air conditioners experience abnormal faults due to excessively high or low bus voltage, leading to inefficient performance and potential shutdowns, particularly during different start modes and low-voltage conditions.
Innovation Solution
A method that involves determining the initial state of the fan by detecting electrical signals from the stator and applying control signals to match the fan's state, using closed-loop control to stabilize bus voltage and rotation speed, and employing different control modes for upwind reverse, downwind forward, and static start states to manage energy flow and prevent voltage abnormalities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the fan operates in upwind reverse start mode, then the fan can start against the wind direction, but the bus voltage rises excessively causing abnormal shutdown
Solution Approach 1:
The control method detects the fan's initial rotation state before startup and preliminarily determines the appropriate control mode based on this detection. By performing this preliminary assessment, the system prepares the appropriate control strategy in advance, preventing excessive bus voltage rise before it occurs during upwind reverse start operation.
Solution Approach 2:
The system continuously monitors the bus voltage and fan rotation state, using this feedback information to dynamically adjust the control mode. When the fan is in generator state during upwind reverse start, the feedback mechanism detects the bus voltage rise and triggers corresponding control actions to maintain voltage stability.
2Productivity
If the fan operates in downwind forward start or static start mode, then the fan can operate efficiently under normal conditions, but the bus voltage decreases excessively under low-voltage input causing abnormal shutdown
Solution Approach 1:
The control method dynamically adjusts the fan's operating parameters based on real-time detection of rotation state and bus voltage conditions. Under low-voltage input conditions, the system modifies the control strategy to prevent excessive bus voltage decrease, allowing the fan to maintain efficient operation while adapting to changing voltage conditions.
Solution Approach 2:
The system changes operational parameters such as frequency and voltage based on the detected initial state and current operating conditions. By adjusting these parameters dynamically, the system prevents bus voltage from decreasing excessively under low-voltage input while maintaining fan productivity.
3Adaptability or versatility
If the fan uses a variable frequency driver with uncontrollable rectifier, then the fan can operate at variable speeds, but the bus voltage becomes uncontrollable leading to frequent abnormal shutdowns
Solution Approach 1:
The control method implements a feedback mechanism that continuously monitors the bus voltage and fan operation state. This feedback enables the system to detect when bus voltage approaches abnormal levels and automatically adjust control parameters to maintain voltage within safe operating ranges, preventing shutdowns while preserving variable speed capability.
Solution Approach 2:
The system performs preliminary detection of the fan's initial rotation state and preliminarily determines the control mode before actual operation begins. This preliminary action allows the system to anticipate potential bus voltage issues and prepare appropriate control strategies, preventing abnormal shutdowns before they occur.
Data Source
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AI summary
Embodiments of the present disclosure provide a method for controlling a fan, a system, and an air conditioner. The method includes: turning off a first bridge arm group in an inverter of the fan; applying a preset driving signal to a second bridge arm group in the inverter; detecting an electrical signal of a stator of the fan after the preset driving signal is applied; determining an initial state of the fan according to the electrical signal of the stator of the fan, wherein the initial state of the fan includes a downwind forward state, a static start state, or an upwind reverse state; and providing the fan with a control signal matching the initial state of the fan according to the initial state of the fan.