Lead Angle Adjustment Circuit for Sensorless Motor Drive
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Solution Overview
Problem
Three-phase motor drive circuits are costly due to complex bias circuitry and sensor requirements, and sensorless configurations may fail to start if inductive voltage is small, with lead angles not optimized for different applications.
Innovation Solution
A motor drive circuit and method that adjusts the lead angle of a position indicator signal using a control circuit and angle adjustment circuit, generating a pseudo FG signal with optimized lead angles for varying speeds by adjusting external pins, allowing for cost and time-efficient implementation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If three-phase motors with Hall sensors are used, then motor performance and position accuracy are improved, but manufacturing cost increases
Solution Approach 1:
The patent extracts and eliminates the Hall sensors from the motor system by implementing a sensorless control approach. The control circuit determines rotor position and speed through signal processing of motor phase currents and voltages, removing the need for physical sensors and their associated bias circuitry, thereby reducing manufacturing cost while maintaining position accuracy.
Solution Approach 2:
The patent replaces the mechanical/electrical Hall sensor system with an electronic signal processing system. Instead of using physical sensors to detect rotor position, the control circuit uses mathematical algorithms to calculate position and speed from electrical measurements, substituting a complex hardware system with a software-based solution.
2Ease of manufacture
If sensorless motor drive configurations are used, then manufacturing cost is reduced, but reliability deteriorates due to failure to start when inductive voltage is small
Solution Approach 1:
The patent implements lead angle adjustment as a controllable parameter that can be optimized for different operating conditions. By dynamically adjusting the lead angle in the control algorithm, the system adapts to varying inductive voltage conditions, ensuring reliable startup even when inductive voltage is small, while maintaining the cost advantages of sensorless operation.
3Device complexity
If fixed lead angle motor drive circuits are used, then device complexity is reduced, but adaptability deteriorates as lead angles are not optimized for different applications
Solution Approach 1:
The patent transforms the static, fixed lead angle into a dynamic, adjustable parameter. The control circuit incorporates lead angle adjustment capability that can be modified based on application requirements, motor speed, and operating conditions. This dynamic approach maintains relatively simple circuit architecture while providing adaptability across different applications through software-based parameter tuning.
Data Source
AI summary
A lead angle adjustment circuit includes a counter that receives an input signal and has an output that is connected to a multiplier circuit. The multiplier circuit has an output connected to a subtractor circuit that has an output connected to a pseudo FG generator circuit. The output of the counter is also connected to a storage register that is coupled to an addition circuit through a range determination circuit, a slope determination circuit, and a multiplier determination circuit. The input signal is input to another counter which is connected to the addition circuit through a start determination circuit and an advance angle calculation circuit. The outputs of the multiplier determination circuit and the advance angle calculation circuit are input to the addition which, which generates a signal is subtracted by the subtractor circuit to generate the signal input into the pseudo FG generator circuit.