Dynamic Lag Angle Control for Permanent Magnet Synchronous Machines
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Solution Overview
Problem
Permanent magnet synchronous machines face inaccuracies in lag angle determination due to mechanical tolerances, especially in smaller motors, leading to inefficiencies and suboptimal performance across various operating points, as the lag angle is typically set for a single operating point, resulting in excess consumption and harmonic issues.
Innovation Solution
Implementing a control method using three Hall effect sensors with a central and two lateral sensors to dynamically adjust the lag angle based on rotor speed, applying a time delay to measurement signals to optimize the lag angle for varying operating conditions, allowing for improved reproducibility and efficiency across all operating points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the lag angle is determined mechanically by offsetting the positioning of Hall effect sensors, then the control is simple and robust, but the accuracy of the lag angle is low due to mechanical tolerances
Solution Approach 1:
The patent replaces the mechanical determination of lag angle (through physical offsetting of Hall sensors) with an electronic/software-based solution. A processing module calculates the lag angle dynamically using sensor signals and rotor position information, eliminating the need for precise mechanical positioning and compensating for mechanical tolerances through computational methods
Solution Approach 2:
The patent makes the lag angle dynamic rather than fixed. The processing module continuously adjusts the lag angle based on operating conditions such as rotor speed, allowing the system to optimize performance across different operating points rather than being constrained by a single mechanically-set angle
2Adaptability or versatility
If the lag angle is set for a single operating point, then the device complexity is low, but the performance is suboptimal at other operating points leading to excess consumption
Solution Approach 1:
The patent implements a dynamic lag angle control where the processing module continuously adjusts the lag angle based on the current operating point (particularly rotor speed). This allows the system to adapt to varying operating conditions and maintain optimal performance across the entire operating range rather than being optimized for a single point
Solution Approach 2:
The patent uses feedback from Hall effect sensors and rotor position information to continuously monitor operating conditions and adjust the lag angle accordingly. The processing module receives real-time data and modifies the control parameters to maintain optimal performance as operating conditions change
3Measurement precision
If three Hall effect sensors are positioned at 120° electrical spacing, then the rotor position can be determined in six sectors, but the lag angle accuracy deteriorates due to mechanical tolerances
Solution Approach 1:
The patent replaces reliance on precise mechanical positioning of Hall sensors with an electronic calculation approach. The processing module computes the lag angle using software algorithms that process sensor signals and rotor position data, thereby eliminating the direct impact of mechanical positioning tolerances on lag angle accuracy
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 ensures optimal performance and efficiency of the inverter-motor combination by dynamically adjusting the lag angle with speed, minimizing power consumption and harmonic distortion, and maintaining performance consistency across different operating points.
Implementation Method 1
Trapezoidal control, also known as '120°' control, uses three Hall effect sensors to detect the angular position of the rotor in six positions. The three sensors serve to subdivide one electrical period of the rotor having a duration of 360° electrical, discretely into six electrical sectors each of 60° electrical.
Implementation Method 2
Variable-speed fans generally include an inverter and a motor that is a permanent magnet synchronous machine. Permanent magnet synchronous machines are generally powered by means of a direct current (DC) power supply via the inverter arranged between the DC power supply and the permanent magnet synchronous machine.
Implementation Method 3
the inverter powers the two appropriate phases of the stator of the synchronous machine for obtaining motor torque
Data Source
AI summary
A permanent magnet synchronous machine includes a permanent magnet rotor and a three-phase stator, the machine being associated with a control inverter for controlling the stator of the machine. A method of controlling the machine includes taking three simultaneous measurements by three respective Hall effect sensors arranged to have a central sensor and two lateral sensors, the two lateral sensors being placed at 120°/p mechanical relative to the central sensor about the rotation axis of the rotor, where p is the number of pairs of poles of the machine; determining the position of the rotor based on the three measurements; controlling the control inverter as a function of the determined position of the rotor; and prior to controlling the inverter, applying a time delay to the three measurement signals so that the control of the control inverter takes account of a variable desired lag angle.