IPMSM Startup Rotor Step Detection Without Sensors
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Solution Overview
Problem
Conventional methods for determining the position of a rotor in permanent magnet synchronous motors, such as rotating the rotor or using Hall-effect sensors, are costly, complex, and can cause rotor movement during startup, which is undesirable in many applications.
Innovation Solution
A method involving applying a sequence of voltage signals to the motor terminals, measuring current changes, and identifying the startup rotor step position based on the highest current measurement without rotating the rotor, utilizing the anisotropic properties of the motor to determine the rotor's position before startup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods such as rotating the rotor or using Hall-effect sensors are used to determine rotor position, then rotor position can be determined, but the cost, complexity, and time increase, and rotor movement may occur during startup
Solution Approach 1:
The patent extracts the rotor position detection function from physical sensors (Hall-effect sensors) and mechanical methods (rotating the rotor), implementing it instead through electrical measurements of current responses to applied voltage sequences. This eliminates the need for additional sensors and mechanical movement while maintaining position detection capability.
Solution Approach 2:
The patent replaces mechanical rotor rotation and physical sensor-based detection with an electrical measurement system. By applying voltage sequences and measuring current responses, the system determines rotor position without mechanical movement or physical sensors, substituting a mechanical/electromechanical system with an electrical field-based system.
2Measurement precision
If Hall-effect sensors are used to determine rotor position, then rotor position can be determined, but cost and complexity increase
Solution Approach 1:
The patent removes the Hall-effect sensor component from the system entirely, extracting the position detection function to be performed instead by the controller through electrical measurements. This eliminates the need for expensive external sensors and reduces manufacturing complexity.
Solution Approach 2:
The motor system performs its own position detection function using its existing components (windings, terminals, controller) without requiring external sensors. The controller uses the motor's electrical characteristics and current responses to self-determine rotor position, making the system self-sufficient.
3Measurement precision
If high frequency injection current is used for sensorless rotor position detection, then rotor position can be determined, but computational demand and processor throughput requirements increase
Solution Approach 1:
The patent changes the detection parameters by using low-frequency or DC voltage sequences instead of high-frequency injection currents. This approach exploits the anisotropic electrical characteristics of the motor at different rotor positions, achieving position detection with simpler computational requirements and standard processor capabilities.
4Measurement precision
If rotor is rotated during startup alignment, then rotor position can be determined, but time to perform the application increases
Solution Approach 1:
The patent performs preliminary electrical measurements during the startup sequence to determine rotor position before the motor begins rotating. By using voltage sequences and current measurements at standstill, the system obtains position information in advance, eliminating the need for subsequent rotor rotation for alignment and reducing overall startup time.
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 allows for accurate rotor position determination without additional sensors or increased computational demand, reducing power draw and enabling higher starting torque while avoiding rotor movement during startup.
Implementation Method 1
utilizing the anisotropic properties of the motor to determine the rotor's position before startup
Data Source
AI summary
Systems, apparatuses, and methods to perform startup step detection in an internal permanent magnet synchronous machine are provided. Startup step detection may providing a motor comprising a rotor and stator, wherein the rotor may be positioned in one of six rotor step positions. The startup step detection may include determining which of the six rotor step positions the rotor is in. This may be performed by determining, prior to starting the motor, a sequence of voltage signals while taking current measurements for each voltage signal. The current measurements may be a change in current over time. Of the current measurements a largest maximum current measurement may be determined, which may be used to identify the current rotor step position.