PMSM Deadzone Error Compensation via Lookup Table
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Solution Overview
Problem
Existing methods for correcting deadzone errors in permanent magnet synchronous motors (PMSM) are either theoretical and ineffective during operation or require additional hardware, leading to decreased control accuracy and reliability.
Innovation Solution
A method involving offline measurement of error data to create a lookup table of current commands and corresponding compensation values, which is stored in a motor controller memory, allowing for online correction of deadzone errors using an electromagnetic calculation equation, thereby improving control precision and adaptability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reference model is used to calculate compensation value prior to mass production, then the control accuracy is improved at the initial stage, but the method cannot compensate errors during operation processes
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing compensation values in a lookup table before mass production. The compensation values are computed offline for various operating conditions and stored in memory, allowing the system to quickly retrieve and apply appropriate compensation during operation without real-time calculation overhead.
Solution Approach 2:
The patent implements feedback by continuously monitoring actual motor parameters during operation and comparing them with expected values. Based on this feedback, the system dynamically selects and applies appropriate compensation values from the pre-computed lookup table, enabling real-time adaptation to operating condition fluctuations.
2Measurement precision
If additional pins on MCU are used to real-time calculate no-load time, then the compensation accuracy is improved, but the hardware complexity increases and reliability decreases
Solution Approach 1:
The patent eliminates the need for additional MCU pins by pre-calculating all necessary compensation values offline and storing them in a lookup table. During operation, the system only needs to retrieve pre-computed values based on measured parameters, avoiding real-time calculation complexity and additional hardware requirements.
Solution Approach 2:
The patent uses a lookup table that copies pre-computed compensation data into memory, allowing the system to access compensation values without performing complex real-time calculations. This approach replaces computational complexity with simple data retrieval operations.
3Reliability
If deadzone time is set to avoid simultaneous turn-on/off of switching transistors, then the motor controller reliability is improved, but the control accuracy deteriorates due to deadzone error
Solution Approach 1:
The patent converts the harmful deadzone error into a beneficial compensation mechanism. By measuring the actual voltage and current during deadzone periods and calculating the resulting error, the system generates compensation values that are stored in the lookup table. This transforms the previously harmful deadzone effect into a corrected and utilized phenomenon for improving control accuracy.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting compensation values based on operating conditions. The lookup table contains different compensation values for various current and voltage levels, allowing the system to select the appropriate compensation parameter that counteracts the deadzone error for each specific operating point.
Data Source
AI summary
A method for correcting a compensation item of a PMSM motor, the method including: offline measuring an error data of a parameter of a PMSM motor in a control process; providing a series of current commands and calculating compensation values of the parameter corresponding to the series of current commands; establishing a lookup table with regard to the series of current commands and the compensation values of the parameter corresponding to the series of current commands; storing the lookup table in a memory of a motor controller; starting and allowing the motor to work at a normal state; and online correcting the error data of the parameter by using the lookup table.