Power Conversion Device Dead Time Error Estimation
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Solution Overview
Problem
Existing power conversion devices struggle to accurately and efficiently calculate the resistance value of an electric motor and dead time error simultaneously, requiring lengthy processes and additional means, which hinders improved control performance in variable-speed electric motor control systems.
Innovation Solution
A power conversion device with a control unit generating switching signals based on different carrier frequencies and a characteristic calculation unit estimating both resistance value and dead time error from operating characteristics obtained under specific switching signal conditions, allowing simultaneous calculation without changing main circuit conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional means are used to obtain dead time error separately, then measurement precision of dead time error is improved, but device complexity increases
Solution Approach 1:
The patent combines the resistance value calculation and dead time error calculation into a single integrated process. Both parameters are calculated simultaneously using the same measurement data obtained during motor operation, eliminating the need for separate measurement systems or additional hardware components.
Solution Approach 2:
The calculation unit is designed to perform multiple functions: it calculates both the resistance value and dead time error using the same input data (voltage and current measurements). This multi-functional approach allows a single component to provide comprehensive motor parameter identification without requiring additional specialized devices.
2Measurement precision
If frequency of AC power supply is changed and measurements are taken at each frequency, then measurement precision of resistance value is improved, but loss of time increases
Solution Approach 1:
The patent performs resistance value calculation continuously during normal motor operation without requiring separate measurement phases. The calculation unit processes voltage and current data in real-time as the motor operates, maintaining continuous monitoring rather than performing discrete measurements at different frequencies.
Solution Approach 2:
The system uses the motor's own operational data (voltage and current during normal operation) to calculate the resistance value. The motor's normal operation serves dual purposes: both driving the load and providing the measurement data needed for parameter identification, eliminating the need for separate test procedures.
3Measurement precision
If multiple measurement procedures are implemented for different parameters, then measurement precision of both resistance value and dead time error is improved, but productivity decreases
Solution Approach 1:
The patent merges the calculation of resistance value and dead time error into a single simultaneous process. Both parameters are derived from the same set of voltage and current measurements taken during motor operation, eliminating the need for sequential measurement and calculation procedures.
Solution Approach 2:
The system performs parameter calculations during normal motor operation rather than requiring preliminary test procedures. The voltage and current data collected during regular operation are immediately used for parameter identification, eliminating the need for separate pre-testing phases.
Data Source
AI summary
A control unit is configured to generate a first switching signal based on a voltage command value and a first carrier and a second switching signal based on the voltage command value and a second different carrier, and a characteristic calculation unit estimates and calculates at least one of a resistance value of an electric motor and a dead time error, which is the difference between an effective value of a dead time and a set value of the dead time, based on a first operating characteristic of a power conversion unit obtained when switching elements are driven with the first switching signal and a second operating characteristic of the power conversion unit obtained when the switching elements are driven with the second switching signal. The resistance value of the electric motor and the dead time error can be quickly calculated and estimated by a common structure.