Magnetic Pole Position Detection Using Dual Voltage Pulse Commands
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Solution Overview
Problem
Conventional methods for estimating the magnetic pole position of synchronous magnet motors have limitations, resulting in an error of ±30° due to the restricted output patterns of voltage vectors, which affects the motor's output characteristics.
Innovation Solution
A magnetic pole position detection device that includes a current detection unit and a calculation unit to generate voltage pulse commands for the inverter, allowing for the estimation of the magnetic pole position by narrowing down the estimation range using first and second voltage pulse commands, which actuate all three legs and only two legs of the inverter respectively, based on motor current responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional voltage pulse commands with six output patterns are used, then the inverter operation is simple, but the magnetic pole position estimation accuracy is limited to ±30°
Solution Approach 1:
The patent segments the voltage pulse command into two distinct types: first voltage pulse commands that actuate all three legs of the inverter, and second voltage pulse commands that actuate only two legs. This segmentation allows the system to use different command patterns for different estimation scenarios, improving accuracy from ±30° to ±15° by combining results from both command types while maintaining manageable operational complexity
Solution Approach 2:
The patent dynamically selects between first and second voltage pulse commands based on the estimation process requirements. The calculation unit generates appropriate voltage pulse commands adaptively, switching between full three-leg actuation and partial two-leg actuation modes to optimize the magnetic pole position estimation accuracy while managing inverter complexity
2Measurement precision
If magnetic pole position is estimated from motor operation, then the estimation can be obtained during rotation, but it cannot be estimated when the motor is mechanically restrained in a stopped state
Solution Approach 1:
The patent applies preliminary action by generating voltage pulse commands that actively excite the motor windings even when the motor is mechanically restrained. The calculation unit generates first and second voltage pulse commands that cause currents to flow through the windings, creating magnetic fields that enable pole position estimation without requiring actual motor rotation, thus enabling estimation in stopped and restrained states
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
This approach enables more accurate estimation of the magnetic pole position, reducing the error to ±15° and further, thereby enhancing the motor's output characteristics.
Implementation Method 1
a calculation unit to generate a voltage pulse command to estimate the magnetic pole position; to output the voltage pulse command to an inverter that drives the synchronous magnet motor; and to estimate the magnetic pole position on a basis of the motor current that flows in response to the voltage pulse command
Implementation Method 2
a current detection unit to detect a motor current flowing to each phase of the synchronous magnet motor
Data Source
AI summary
A magnetic pole position detection device of a motor control device includes a calculation unit to estimate a magnetic pole position. The calculation unit generates a voltage pulse command for three-phase connection to actuate all of three legs included in an inverter, and a voltage pulse command for one phase opened to actuate only two of the three legs, and narrows down the estimation range on the basis of a first magnetic pole position estimated value estimated on the basis of a motor current that flows during application of the voltage pulse command for three-phase connection, and a second magnetic pole position estimated value estimated on the basis of a motor current that flows during application of the voltage pulse command for one phase opened.