Motor Resolver Offset Detection Using Voltage Phase Difference
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Solution Overview
Problem
Conventional motor systems using resolvers struggle to accurately detect rotation angles due to external factors like jerky vehicle driving, leading to undetected physical offsets that can cause inaccurate motor control.
Innovation Solution
A motor apparatus with an inverter controller that calculates and detects the offset angle of a rotation angle sensor using a difference between measured and theoretical voltage phases, allowing for efficient detection of physical offsets without additional external apparatus, and implementing fail-safe controls when high-speed conditions are met to prevent motor control failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional resolver-based rotation angle detection is used, then the system can detect rotation angles under normal conditions, but physical offsets (angular offsets) of the resolver cannot be detected due to external factors like jerky driving
Solution Approach 1:
The system performs preliminary calibration to detect the physical offset angle of the rotation angle sensor before normal operation. By calculating the offset angle based on the difference between measured and theoretical voltage phases during a calibration phase, the system prepares correction data that will be applied during subsequent motor control operations, enabling accurate detection even after jerky driving events
Solution Approach 2:
The system continuously monitors the voltage phase difference between measured and theoretical values to detect resolver abnormalities. By comparing the calculated offset angle against threshold values and monitoring changes over time, the system provides feedback to determine when physical offset has occurred, enabling real-time detection of resolver degradation or damage
2Measurement precision
If additional external apparatus are used to detect physical offsets, then detection accuracy improves, but device complexity and cost increase
Solution Approach 1:
The inverter controller utilizes its existing computational resources and voltage measurement capabilities to calculate the offset angle internally. The system serves itself by using the same hardware components (voltage sensors, processor) already present for motor control to perform offset detection, eliminating the need for separate detection apparatus and reducing overall system complexity
Solution Approach 2:
The inverter controller is designed to perform multiple functions: it controls the inverter for motor drive, calculates the offset angle for detection, determines calculation implementation conditions, and notifies abnormalities. This multi-functional approach allows a single device to handle both motor control and offset detection tasks, reducing the need for additional specialized components
3Reliability
If the calculator continuously calculates offset angles, then detection reliability improves, but computational efficiency decreases due to unnecessary calculations
Solution Approach 1:
The determination component evaluates specific conditions (motor current, system state, motor speed) periodically to decide when offset angle calculation should be performed. Rather than continuous calculation, the system triggers calculations only when predetermined conditions are met, such as during calibration phases or when abnormality indicators are detected, optimizing computational resource usage while maintaining detection reliability
Solution Approach 2:
The system performs offset angle calculation during predetermined calibration phases before normal operation begins. By completing the calculation in advance when conditions are favorable (motor stationary or at known state), the system avoids continuous computation during operation, improving efficiency while ensuring detection capability is established beforehand
4Speed
If offset angle calculation is performed without condition checking, then calculation speed improves, but energy consumption and unnecessary operations increase
Solution Approach 1:
The determination component creates a periodic evaluation cycle that checks whether predetermined conditions (motor current, system state, motor speed) are satisfied before allowing calculation. This conditional periodic execution prevents continuous computation, reducing energy consumption while maintaining the ability to perform calculations quickly when conditions are met
Solution Approach 2:
The system performs preliminary condition checking (evaluating motor current, system state, and speed) before initiating the offset angle calculation. By pre-evaluating whether calculation is necessary and feasible, the system avoids wasting energy on unnecessary computations while ensuring that when calculation is triggered, it can proceed immediately without delay
Data Source
AI summary
A motor apparatus is provided. The motor apparatus includes a motor having a rotor and a stator, an inverter used to covert an input voltage into a three-phase alternating current (AC) voltage and provide the three-phase AC voltage to the motor, an inverter controller used to control the inverter, and a rotation angle sensor. The rotation angle sensor is fixed to the motor and is used to detect a rotation angle of the motor. The inverter controller includes a calculator. The calculator calculates an offset angle of an installation position of the rotation angle sensor according to a difference between a measured value and a theoretical value of a voltage phase of the motor.