Sensorless Motor Drive Angle Estimation via Induced Voltage
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Solution Overview
Problem
Existing motor drive devices for brushless motors in vehicles require a magnetic pole sensor for angle detection, leading to increased size and wiring complexity, and struggle to estimate motor rotation angles accurately across all speed regions without significant cost increases.
Innovation Solution
A sensorless motor drive device that estimates motor rotation angles using induced voltage in high-speed regions and vehicle speed pulses in low-speed regions, employing a microcomputer-based controller to switch between rectangular wave and sine wave control, eliminating the need for a magnetic pole sensor and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic pole sensor is used to detect motor rotation angle, then angle detection accuracy is improved, but device size increases and wiring complexity increases
Solution Approach 1:
The patent extracts the angle detection function from a separate magnetic pole sensor and integrates it into the existing controller by using the motor's own induced voltage signals. This eliminates the need for additional sensors and their associated wiring, while maintaining angle detection capability through sensorless control algorithms.
Solution Approach 2:
The motor system uses its own induced voltage signals to perform angle detection, rather than requiring an external sensor. The controller processes the back-EMF signals generated by the motor during operation to estimate rotor position, enabling the system to self-diagnose and self-control without additional components.
2Measurement precision
If a magnetic pole sensor is used to detect motor rotation angle, then angle detection accuracy is improved, but production cost increases
Solution Approach 1:
The patent replaces expensive magnetic pole sensors with a software-based sensorless control algorithm that uses existing inexpensive circuitry. The controller processes freely available induced voltage signals through computational algorithms to achieve angle detection, eliminating the need for costly sensor hardware and reducing overall system production costs.
Solution Approach 2:
The patent replaces the mechanical/electrical sensor system with a computational/software-based solution. Instead of using physical sensors to detect rotor position, the system uses mathematical algorithms to estimate angle from electrical signals, substituting hardware complexity with software intelligence.
3Device complexity
If sensorless control is implemented to reduce cost and complexity, then device complexity is reduced and production cost decreases, but angle estimation accuracy in low-speed regions deteriorates
Solution Approach 1:
The patent implements dynamic switching between different control algorithms based on operating conditions. In high-speed regions, standard induced voltage-based estimation is used, while in low-speed regions, the system dynamically switches to alternative estimation techniques that account for reduced back-EMF signals, maintaining accuracy across the full speed range.
Solution Approach 2:
The patent changes the estimation parameters and algorithms based on motor speed conditions. At low speeds where induced voltage is weak, the system adjusts its estimation parameters and uses different calculation methods to maintain accurate angle estimation, whereas at high speeds the standard methods suffice.
4Measurement precision
If induced voltage-based angle estimation is used in high-speed regions, then angle estimation accuracy is improved, but control stability in low-speed regions deteriorates
Solution Approach 1:
The patent dynamically adapts the control strategy based on motor speed. In high-speed regions, induced voltage-based estimation provides accurate angle information for stable control. In low-speed regions, the system dynamically switches to alternative estimation methods that maintain control stability when induced voltage signals become too weak for reliable estimation.
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
Enables accurate estimation and control of motor rotation angles across all speed regions without increasing production costs, ensuring stable low-speed operation and efficient high-speed performance, while avoiding the need for complex arithmetic circuits and costly sensor systems.
Implementation Method 1
A sensorless motor drive device that estimates motor rotation angles using induced voltage in high-speed regions
Data Source
AI summary
A motor drive device includes a vehicle speed sensor generating a pulse signal at a predetermined rotation angle of an output shaft in a power transmission system. The motor drive device is configured to perform: an initial setting process; an acquisition process; a detection process; a sine wave control process; and an abnormality determination process.