AC Motor Vector Control Using Resolver Angle Multiplication
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Solution Overview
Problem
The use of resolvers with a limited number of poles in multipolar alternating-current electric motors leads to phase differences and noise, making stable vector control difficult.
Innovation Solution
A control device that adjusts the ratio between the number of polar pairs of the electric motor and the axial double angle of the position sensor to an integer multiple, using electrical angle phase and rotation number calculations to stabilize vector control, and incorporates filter processing to suppress noise components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a resolver with a limited number of poles is used in a multipolar alternating-current electric motor, then the device complexity is reduced, but the measurement precision of the electrical angle phase deteriorates due to phase difference
Solution Approach 1:
The patent applies parameter changes by modifying the relationship between the resolver pole number and motor pole number. Specifically, it sets the ratio between the number of polar pairs of the motor and the axial double angle of the resolver to an integer multiple, and uses electrical angle phase calculation to multiply the resolver angle information by this integer multiple to obtain accurate electrical angle phase information, thereby resolving the phase difference issue while maintaining a simple resolver configuration
Solution Approach 2:
The patent introduces an intermediary calculation process between the resolver and the control system. The electrical angle phase calculation unit acts as an intermediary that processes the resolver angle information through multiplication by an integer multiple, converting it into accurate electrical angle phase information that accounts for the pole number difference, thus enabling precise control despite using a resolver with fewer poles than the motor
2Reliability
If a resolver is used to detect rotation position and speed, then the reliability in environmental resistance is improved, but object-generated harmful factors increase due to noise proportional to rotation number
Solution Approach 1:
The patent converts the harmful noise effect into a beneficial filtering opportunity. By establishing the integer multiple relationship between motor polar pairs and resolver axial double angle, the noise frequency becomes predictable and proportional to the rotation number. This allows the control system to apply targeted frequency filtering to remove the noise while preserving the useful signal, thereby maintaining the resolver's environmental reliability while eliminating its noise drawback
Solution Approach 2:
The patent implements feedback by continuously monitoring the angle signal from the resolver and applying dynamic filtering based on the detected noise characteristics. The control system uses the known relationship between rotation number and noise frequency to adaptively filter out noise components, ensuring that the angle information used for control remains accurate even as operating conditions change
3Productivity
If the number of poles of the motor is increased for miniaturization and high power density, then the productivity is improved, but the difficulty of detecting and measuring increases due to phase difference with the resolver
Solution Approach 1:
The patent enables high-power-density multipolar motor design by changing the parameter relationship between motor poles and resolver poles. By setting the motor polar pairs to an integer multiple of the resolver axial double angle, the system can handle motors with many poles (higher productivity/power density) while using a standard resolver, and the electrical angle phase calculation compensates for the pole number difference to maintain accurate detection
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 stable vector control of multipolar alternating-current electric motors by accurately calculating electrical angles and reducing noise, thereby improving control stability and efficiency.
Implementation Method 1
A resolver is a sensor that is mounted to a rotation shaft, rotates together with the rotation shaft, and converts a mechanical angle of the rotation shaft into an electric signal using electromagnetic induction
Data Source
AI summary
The control device controls an alternating-current electric motor via an inverter based on angle information of a position sensor. The position sensor is set such that the ratio between the number of polar pairs of the alternating-current electric motor and the axial double angle X of the position sensor is an integer multiple. The control device includes an electrical angle phase calculation unit that multiplies angle information detected by the position sensor by an integer multiple and converts the multiplied angle information into electrical angle phase information, an electrical angle rotation number calculation unit that calculates an electrical angle rotation number based on the electrical angle phase information calculated by the electrical angle phase calculation unit, and a vector control unit that calculates a voltage command value to be output to the inverter based on the electrical angle phase information.