Sensorless PMSM Speed Control via Soft Starter Torque Corridor
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Solution Overview
Problem
Current solutions for starting and operating high-efficiency permanent magnet synchronous machines on stiff power supplies are hindered by high starting currents and the need for sensor systems, making them costly and impractical for wide application.
Innovation Solution
A method for controlling a three-phase permanent magnet machine using a soft starter with thyristors, which calculates all possible firing times and determines a torque corridor based on actual and setpoint torque, allowing for sensorless operation and efficient speed control without additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sensor system is used to detect speed and position for closed-loop control, then control precision and reliability are improved, but system cost and complexity increase
Solution Approach 1:
The patent extracts and eliminates the sensor system from the control architecture, achieving sensorless control by using the existing soft starter circuitry to provide all necessary control functions including speed and position detection through intelligent algorithms
Solution Approach 2:
The system uses itself for control - the soft starter's own circuitry and components are utilized to provide sensorless control functions, eliminating the need for external sensors while maintaining control reliability
2Object-affected harmful factors
If a soft starter is used to reduce starting current, then power supply stress is reduced, but speed control capability is lost
Solution Approach 1:
The patent implements dynamic control by continuously adjusting the firing angles of the soft starter thyristors based on real-time motor speed and load conditions, enabling the soft starter to provide both current limitation and active speed control throughout the startup process
Solution Approach 2:
The system incorporates feedback mechanisms where the controller continuously monitors motor current, voltage, and position to calculate speed, using this information to adjust firing angles and maintain desired speed profiles while limiting starting current
3Power
If leading-edge phase control is used to reduce voltage during switching-on, then starting current is limited, but torque control precision deteriorates
Solution Approach 1:
The controller pre-calculates optimal firing angle sequences based on expected load conditions and motor parameters, preparing torque profiles in advance to ensure smooth acceleration with precise torque control from the moment of startup
Solution Approach 2:
The system dynamically changes multiple parameters including firing angles, pulse widths, and switching frequencies to optimize both current limitation and torque control precision across different operating conditions
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
Enables efficient and cost-effective operation of high-efficiency motors by eliminating the need for sensors, allowing for smooth starting and speed control, including reversing direction, with reduced energy consumption and increased application flexibility.
Implementation Method 1
calculates all possible firing times of the thyristors of the soft starter and determines a torque which is assigned to each firing time, resulting from the firing of the thyristors at a respective firing time
Implementation Method 2
permanent magnet synchronous machine (PMSM)... permanent magnets in the rotor is increasingly desired
Data Source
AI summary
A battery state estimating apparatus as an embodiment includes a state estimator, a power estimator, and a determiner. The state estimator estimates a state of a battery. The power estimator estimates first power amount charged/discharged by the battery within a charging/discharging period, based on the state. The determiner compares the first power amount with second power amount inputted/outputted to/from the battery within the charging/discharging period and thereby determines validity of the state.