Sensorless Field Oriented Control for AC to DC Power Conversion
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Solution Overview
Problem
Converting AC power to DC power in portable generators is challenging due to variations in motor speed, which require costly sensor-based systems for rotor position feedback, affecting reliability and cost-effectiveness.
Innovation Solution
A field-oriented controller using a sliding mode observer estimates the rotor position without hardware sensors, allowing for stable regulated DC power output by adjusting the rectifier duty cycle and voltage compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional sensor-based rotor position feedback devices are used, then the DC output voltage regulation is improved, but the system cost and complexity increase
Solution Approach 1:
The patent replaces mechanical sensor-based rotor position feedback systems with a sensorless field-oriented control system that uses software algorithms to estimate rotor position and speed from electrical measurements, thereby reducing device complexity and cost while maintaining voltage regulation performance
Solution Approach 2:
The patent creates a virtual model of the rotor position and speed through software estimation algorithms that replicate the functionality of physical sensors, allowing the control system to operate with the same precision as sensor-based systems without the associated complexity
2Measurement precision
If optical encoders or mechanical sensors are used to measure rotor position, then the rotor position accuracy is improved, but the system reliability decreases and cost increases
Solution Approach 1:
The patent extracts the essential measurement function from physical sensors and implements it through software-based estimation algorithms, eliminating the need for optical encoders or mechanical sensors while maintaining the ability to accurately determine rotor position and speed
Solution Approach 2:
The patent replaces expensive, fragile sensor components with computationally-based solutions that have no moving parts or optical components, thereby improving reliability and reducing system cost
3Adaptability or versatility
If motor speed varies by several thousand rpm, then the generator's adaptability is improved, but the DC output voltage stability deteriorates
Solution Approach 1:
The patent implements a dynamic control system that continuously adapts to varying motor speeds by using real-time electrical measurements to estimate rotor position and speed, allowing the system to maintain stable DC output voltage across a wide speed range through active compensation
Solution Approach 2:
The patent changes the control approach from fixed-parameter voltage regulation to variable-parameter field-oriented control, where control parameters are dynamically adjusted based on estimated rotor position and speed, enabling stable operation across varying motor speeds
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
This approach eliminates the need for costly sensors, enhancing reliability and reducing costs while maintaining stable high voltage DC power output across varying motor speeds.
Implementation Method 1
AC generators convert mechanical energy, which can be produced by gasoline or diesel motors, into electrical energy
Implementation Method 2
estimating a back electromotive force (EMF) using the sliding mode observer that uses the estimated AC voltages, and estimating the rotor position using the estimated back EMF
Data Source
AI summary
High voltage DC power, which is produced by rectifying AC power generated by an AC generator, is controlled and regulated without the need for measuring the position of the rotor with hardware. A Field oriented controller uses a sliding mode observer to estimate the position of the rotor without the use of position detection hardware. The estimated position of the rotor and the AC current are then used by the field oriented controller algorithm to regulate a DC output from a rectifier driven by an AC generator.