PMSM Bus Current Estimation Using Rotor Position Compensation
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Solution Overview
Problem
Existing bus current estimation methods for permanent magnet synchronous motors are restricted by working conditions, leading to increased difficulty in controlling the motor.
Innovation Solution
A control method and controller that compensates the rotor position using motor speed, transforms quadrature-axis and direct-axis currents into real-time three-phase currents, determines a bus current estimated value, and low-pass filters it to obtain a target bus current value for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If software estimation with adjustment coefficient is used to obtain bus current, then cost is saved and system reliability is improved, but the method is limited to maximum one-cycle compensation and cannot accurately grasp bus current at any time
Solution Approach 1:
The patent pre-calculates and stores compensation values in a lookup table before operation. The compensation table is built offline with pre-computed correction factors for different operating conditions, allowing the controller to quickly retrieve and apply appropriate compensation without real-time complex calculations, thus achieving accurate bus current estimation across all working conditions while maintaining system reliability
Solution Approach 2:
The patent changes the estimation approach by introducing multiple compensation parameters stored in a lookup table rather than using a single adjustment coefficient. The system selects different compensation parameters based on actual working conditions (current magnitude, frequency, etc.), transforming a fixed-parameter estimation into a variable-parameter estimation that adapts to different operating states, thereby achieving accurate bus current measurement across all conditions
2Device complexity
If maximum one-cycle compensation is applied, then calculation complexity is reduced, but the method is easy to be limited by working conditions and not flexible enough
Solution Approach 1:
The patent pre-calculates and stores compensation values in a lookup table before operation. The compensation table is built offline with pre-computed correction factors for different operating conditions, allowing the controller to quickly retrieve and apply appropriate compensation without real-time complex calculations, thus achieving accurate bus current estimation across all working conditions while maintaining system reliability
Solution Approach 2:
The system uses itself to generate the compensation data needed for operation. The lookup table is built using the same estimation algorithm and system parameters, allowing the system to self-calibrate and adapt to its own characteristics without requiring external calibration equipment or complex external setup, thereby achieving both simplicity and versatility
Data Source
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AI summary
The present application provides a control method and a controller, the method includes: collecting a rotor position, a motor speed, a quadrature-axis current, a direct-axis current and pulse width modulation duty cycles of three-way bridge arms of the permanent magnet synchronous motor, compensating the rotor position by using the motor speed, to obtain a real-time rotor position, transforming the quadrature-axis current and the direct-axis current into a real-time three-phase current according to the real-time rotor position, according to the real-time three-phase current and the pulse width modulation duty cycles of the three-way bridge arms, determining a bus current estimated value, low-pass filtering the bus current estimated value, to obtain a target bus current value, and controlling the permanent magnet synchronous motor according to the target bus current value. The control method of the present application allows the compensation of a three-phase current at any position, and in all working conditions, no matter whether the motor speed is high or low, there is a high estimation accuracy, which enables engineers to grasp the bus current at any time, and then realizes the precise control of the permanent magnet synchronous motor.