Permanent Magnet Synchronous Motor Parameter Estimation Without Signal Injection
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Solution Overview
Problem
Existing methods for estimating all four parameters of a permanent magnet synchronous motor face challenges such as rank deficiency in state equations, leading to inaccurate parameter estimation and performance degradation due to signal injection, which increases motor loss and torque ripple.
Innovation Solution
The solution involves utilizing a stator current ripple model in conjunction with the state equation to estimate d-axis inductance, q-axis inductance, flux linkage, and stator resistance without additional signal injection, thereby addressing the rank deficiency and improving estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If signal injection method is used to estimate four parameters, then parameter estimation is achieved, but motor loss and torque ripple increase
Solution Approach 1:
The patent extracts and utilizes the naturally occurring stator current ripple signal that already exists during normal motor operation, removing the need for additional signal injection. By filtering and processing this existing ripple signal, the system obtains sufficient information for parameter estimation without introducing harmful external signals, thereby reducing motor loss while maintaining estimation accuracy.
Solution Approach 2:
The motor's own operating signals (stator current ripple) are used for parameter estimation rather than requiring external test signals. The system serves itself by utilizing the naturally generated electrical signatures during normal operation to diagnose and estimate its own parameters, eliminating the need for separate signal injection processes that cause energy loss.
2Measurement precision
If signal injection method is used to estimate four parameters, then parameter estimation is achieved, but torque ripple increases
Solution Approach 1:
The patent extracts and utilizes the naturally occurring stator current ripple signal that already exists during normal motor operation, removing the need for additional signal injection. By filtering and processing this existing ripple signal, the system obtains sufficient information for parameter estimation without introducing harmful external signals, thereby reducing motor loss while maintaining estimation accuracy.
Solution Approach 2:
The patent converts the naturally occurring stator current ripple, which is typically considered noise or disturbance, into a useful signal for parameter estimation. By applying band-pass filtering and signal processing techniques, the system transforms this inherent ripple into valuable information for estimating motor parameters, turning a potential harmful factor into a beneficial resource.
3Reliability
If state equation method is used to estimate parameters, then convergence is achieved with two parameters, but rank deficiency problem occurs when estimating three or more parameters
Solution Approach 1:
The patent merges two different approaches: the state equation method (which provides reliable convergence for two parameters) and the stator current ripple analysis method (which provides additional independent equations). By combining these methods, the system achieves reliable parameter estimation for all four parameters while maintaining the convergence guarantees of the state equation approach and overcoming its rank deficiency limitation.
Solution Approach 2:
The patent adds another dimension to the parameter estimation problem by introducing stator current ripple analysis as a supplementary method. This additional dimension provides extra independent equations that, when combined with the state equation method, resolve the rank deficiency issue and enable estimation of all four parameters with maintained convergence reliability.
Data Source
AI summary
Disclosed is a method and apparatus for real-time estimation of full parameters of a permanent magnet synchronous motor. According to this method and apparatus, it is possible to estimate in real time all four parameters of a permanent magnet synchronous motor without additional signal injection. In addition to the state equation, the “stator current ripple model” is additionally used to fundamentally solve the rank deficiency problem in the state equation without injecting additional signals. All four parameters of a permanent magnet synchronous motor can be estimated in real time.