Dual Motor Drive System Sensorless Control
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Solution Overview
Problem
Existing drive systems for synchronous motors face instability in the low-speed range when using position sensorless control with a single power inverter, particularly when driving two synchronous motors in parallel, due to increased output voltage errors and decreased speed electromotive force.
Innovation Solution
A drive system that includes current detectors for both synchronous motors, magnetic pole position estimation units, and a control unit to output voltage commands based on torque and magnetic flux current commands, along with a pulsating component extraction unit to stabilize rotation by determining the angle difference between the motors' magnetic pole positions, thereby preventing unstable rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If two synchronous motors are driven in parallel by a single power inverter using position sensorless control, then cost is reduced by eliminating position sensors and reducing inverter数量, but operation stability deteriorates in the low-speed range due to decreased speed electromotive force and increased output voltage errors
Solution Approach 1:
The control unit determines the magnetic pole position of each synchronous motor by detecting the phase current and using feedback control based on the relationship between phase current, voltage command, and magnetic pole position. This feedback mechanism enables accurate magnetic pole position estimation without position sensors, resolving the contradiction between cost reduction and operation stability in the low-speed range.
2Device complexity
If position sensorless control is used to reduce device complexity, then the number of position sensors is eliminated, but measurement precision of magnetic pole position deteriorates due to output voltage errors becoming relatively large at low speeds
Solution Approach 1:
The patent replaces the mechanical position sensor system with an electrical measurement system that estimates magnetic pole position based on phase current detection and voltage command information. This substitution eliminates position sensors while maintaining measurement precision through mathematical relationships between electrical parameters, particularly effective in the low-speed range where sensorless control traditionally fails.
Data Source
AI summary
A drive system includes a current detection unit that detects a current flowing to a main synchronous motor, and a current detection unit that detects a current flowing to a secondary synchronous motor. The drive system includes a magnetic pole position estimation unit that estimates the magnetic pole position of the rotor of the main synchronous motor, and a magnetic pole position estimation unit that estimates the magnetic pole position of the rotor of the secondary synchronous motor. The drive system includes a current control unit that outputs a voltage command, and a secondary torque current pulsating component extraction unit that extracts a pulsating component. The drive system includes a subtracter that determines an angle difference, and a magnetic flux current command determination unit that determines a magnetic flux current command.