Brushless DC Motor Pump Position Control
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Solution Overview
Problem
Current pumping systems in semiconductor manufacturing face challenges in achieving precise and repeatable position control of mechanical pistons, leading to issues with fluid dispensing accuracy and pressure variation, which can damage expensive photochemicals and affect the uniformity of coatings on semiconductor wafers.
Innovation Solution
A motor-driven pumping system utilizing a permanent-magnet synchronous motor (PMSM) or brushless DC motor (BLDCM) with digital signal processor (DSP) and field-oriented control (FOC), along with real-time position feedback, to provide precise and repeatable position control, reducing heat generation and vibration, and allowing operation across a wide range of speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional stepper motors with electromagnetic clutch/breaking mechanisms are used, then the pump can achieve basic positioning, but vibration and pressure spikes occur during operation
Solution Approach 1:
The patent replaces traditional stepper motors with electromagnetic clutch/breaking mechanisms with brushless DC motors that use electronic commutation and feedback control. This substitution eliminates the mechanical vibration and pressure spikes associated with electromagnetic clutch mechanisms while maintaining precise position control through electronic feedback loops and sinusoidal current control.
Solution Approach 2:
The patent implements feedback control using encoders to monitor motor position and velocity, and pressure sensors to monitor fluid pressure. This feedback is used in closed-loop control algorithms to adjust motor commands in real-time, eliminating the open-loop instability of traditional stepper motors and preventing pressure spikes through proactive pressure regulation.
2Manufacturing precision
If high precision position control is achieved through increased sampling frequency, then dispensing accuracy improves, but heat generation and energy consumption increase
Solution Approach 1:
The patent implements dynamic sampling frequency adjustment where the control system adapts the sampling rate based on operational conditions. During critical dispensing phases, higher sampling frequencies are used for maximum precision, while during transitional phases, lower frequencies reduce computational load and heat generation. This dynamic adaptation maintains accuracy when needed while minimizing energy consumption overall.
3Manufacturing precision
If multiple stage pumps are used to achieve precise fluid delivery, then dispensing control improves, but system complexity and susceptibility to pressure spikes increase
Solution Approach 1:
The patent extracts the pressure regulation function from a separate mechanical pressure control mechanism and integrates it directly into the motor control system through electronic feedback and software algorithms. This eliminates the need for additional mechanical pressure control components in multi-stage pumps, reducing system complexity while maintaining precise fluid delivery control through coordinated control of multiple pump stages.
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 system achieves real-time, smooth motion with extremely precise and repeatable position control over fluid movements and dispense amounts, minimizing fluid damage and ensuring uniform coating applications while reducing energy consumption and operational complexity.
Implementation Method 1
A motor-driven pumping system utilizing a permanent-magnet synchronous motor (PMSM) or brushless DC motor (BLDCM)
Implementation Method 2
field-oriented control (FOC), along with real-time position feedback
Data Source
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AI summary
Embodiments of the systems and methods disclosed herein utilize a brushless DC motor (BLDCM) to drive a singie-stage or a multi-stage pump in a pumping system for real time, smooth motion, and extremely precise and repeatable position control over fluid movements and dispense amounts, useful in semiconductor manufacturing. The BLDCM may employ a position sensor for real time position feedback to a processor executing a custom field-oriented control scheme. Embodiments of the invention can reduce heat generation without undesirably compromising the precise position control of the dispense pump by increasing and decreasing, via a custom control scheme, the operating frequency of the BLDCM according to the criticality of the underlying function(s). The control scheme can run the BLDCM at very low speeds while maintaining a constant velocity, which enables the pumping system to operate in a wide range of speeds with minimal variation, substantially increasing dispense performance and operation capabilities.