Variable Speed Fan Motor Controller with Current Sensing
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Solution Overview
Problem
Current variable speed fan motors with DC brushless permanent magnetic motors have limitations such as single-functionality, low reliability, large and costly current transformers, and complex installation, making them inflexible and difficult to produce in large scales.
Innovation Solution
A variable speed fan motor design integrating a microprocessor, inverter circuit, gear detection circuit, and power supply with current sensing units, allowing adaptable operation and communication with external devices, reducing volume and production costs, and enhancing heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If current transformers are used to detect the state of each power input line, then detection function is achieved, but device volume increases and heat dissipation performance deteriorates
Solution Approach 1:
The patent replaces the traditional current transformer (electromagnetic detection method) with a voltage division circuit using resistors and a microprocessor ADC interface (electronic detection method). This substitution eliminates the need for bulky current transformers while achieving the same detection function, directly resolving the contradiction between detection capability and device volume.
2Difficulty of detecting and measuring
If current transformers with multiple sensing units are embedded in motor wiring plug, then detection coverage is improved, but installation complexity increases and production efficiency decreases
Solution Approach 1:
The patent extracts the detection function from the motor wiring plug assembly and relocates it to the motor controller housing. The voltage division circuits are integrated into the controller's circuit board, separating the detection system from the motor assembly. This extraction simplifies motor installation while maintaining full detection coverage through the controller's centralized detection architecture.
3Device complexity
If simple control circuit is used to substitute PSC motor, then system complexity is reduced, but functionality becomes single and adaptability decreases
Solution Approach 1:
The patent implements multi-functionality in the motor controller through software programming of the microprocessor. The controller can detect power input line states, control motor speed via PWM, reverse motor rotation, and adapt to different workplaces by selecting different operating modes. This software-based multi-functionality maintains simple hardware while achieving high adaptability across different application scenarios.
Solution Approach 2:
The patent introduces dynamic adaptability through the microprocessor, which can dynamically adjust control parameters based on detected power input line states and selected operating modes. The controller dynamically switches between different control strategies (e.g., different PWM duty cycles, different rotation directions) to adapt to varying workplace requirements, resolving the contradiction between simplicity and adaptability.
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 improves reliability, broadens application range, simplifies installation, and reduces production costs, enabling efficient and scalable production of variable speed fan motors.
Implementation Method 1
The gear detection circuit comprises a plurality of current sensing units. Each power input line is connected to one current sensing unit, respectively.
Implementation Method 2
an inverter circuit, a gear detection circuit, and a power supply. An output end of the power supply supplies power to each circuit
Implementation Method 3
A DC brushless permanent magnetic (BPM) motor is utilized to substitute a permanent-split capacitor (PSC) motor
Data Source
AI summary
A variable speed fan motor, including a variable speed motor body and a motor controller. The motor controller includes a microprocessor, an inverter circuit, a gear detection circuit, and a power supply. The gear detection circuit includes a plurality of current sensing units. Only one of the power input lines is in an energized state, and remaining power input lines are in a deenergized state. Each power input line is connected to one current sensing unit. An output end of the current sensing unit is connected to an input end of the microprocessor. The microprocessor selects operating parameters of the motor according to a detected signal of energization state of each power input line. The microprocessor is connected to the series communication unit. The microprocessor communicates with an external device via the series communication unit.