Motor Controller Fixed Output Power Current Limit Segmentation
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Solution Overview
Problem
Conventional motor controllers fail to maintain fixed output power when foreign bodies block the wind flow path in blower fans, leading to increased motor speed and decreased current, which prevents achieving maximum output power even with closed loop control methods.
Innovation Solution
A motor controller with a switch circuit, pre-driver, duty cycle control circuit, current limit circuit, and pulse width modulation control unit, utilizing a resistor for sensing motor current and generating multiple current limit values to maintain fixed output power by adjusting duty cycles and current limits within the maximum rated current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the motor controller uses conventional single current limit control, then the control circuit is simple, but it cannot maintain fixed output power when wind flow is obstructed
Solution Approach 1:
The patent segments the current limit control into multiple discrete current limit values (first current limit value, second current limit value, etc.) stored in the current limit circuit. This segmentation allows the controller to select appropriate current limits based on operating conditions, enabling fixed output power maintenance while keeping each individual limit value simple and manageable.
Solution Approach 2:
The patent implements dynamic current limit adjustment by switching between different current limit values based on the duty cycle and operating conditions. The pulse width modulation control unit dynamically selects from multiple current limit values stored in the current limit circuit, allowing the system to adapt to changing wind flow conditions and maintain fixed output power.
2Productivity
If the motor controller increases motor speed to clear foreign bodies, then the wind flow increases, but the motor current decreases and maximum output power cannot be achieved
Solution Approach 1:
The patent implements feedback control by continuously monitoring the motor current through the sensing pin and resistor, comparing it against multiple stored current limit values, and adjusting the duty cycle accordingly. The pulse width modulation control unit uses this feedback to maintain the motor current within optimal ranges, ensuring both high wind flow and maximum output power are achieved simultaneously.
Solution Approach 2:
The patent changes the current limit parameter dynamically by selecting from multiple stored current limit values based on the operating duty cycle. When wind flow obstruction is detected, the system adjusts the current limit parameter to higher values, allowing the motor to deliver maximum power while maintaining the productivity needed to clear foreign bodies.
3Reliability
If the motor controller uses multiple current limit values, then fixed output power can be maintained, but the control complexity increases
Solution Approach 1:
The patent stores multiple current limit values in advance in the current limit circuit before operation begins. This preliminary action eliminates the need for complex real-time calculations during operation, as the pulse width modulation control unit simply needs to select from pre-stored values based on the duty cycle, maintaining reliability while minimizing control complexity.
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
Enables the motor controller to maintain fixed output power by operating within multiple current limit values, preventing motor damage and ensuring efficient operation even when wind flow is obstructed, through closed loop control and precise duty cycle adjustments.
Implementation Method 1
The resistor is coupled to the terminal S and a terminal GND, where the terminal S may be coupled to a sensing pin. The switch circuit includes a first transistor, a second transistor, a third transistor, and a fourth transistor for supplying a motor current to the motor coil. The terminal S and the resistor can be used for sensing the motor current.
Data Source
AI summary
A motor controller comprises a switch circuit, a pre-driver, a duty cycle control circuit, a current limit circuit, a pulse width modulation control unit, and a resistor. The motor controller is configured to drive a motor, where the motor has a motor coil and a maximum rated current. The switch circuit is configured to supply a motor current to the motor coil. The pre-driver generates a plurality of driving signals to control the switch circuit. The current limit circuit may store a current limit graph. The motor controller attains a function of maintaining a fixed output power by a plurality of current limit values, where each of the current limit values is less than or equal to the maximum rated current.