A control device and method for an AC excitation synchronous motor

Abstract

The present invention is an AC excitation synchronous motor control device and method, which belongs to the field of electromechanical control engineering. The present invention uses a variable frequency controller to perform AC excitation on the rotor winding of a wound motor, and controls the excitation current of the motor through the rotor to improve the excitation efficiency. The capacity of the system is reduced to less than 20% of the motor capacity, which greatly reduces the capacity of the frequency conversion controller and greatly reduces the equipment cost. The active power of the motor operation is provided by the stator winding through the power grid, and can be controlled to the stator side power factor of 1. Excitation control makes the speed control system more reasonable and efficient, enabling four-quadrant operation.

Description

technical field [0001] The invention belongs to the field of electromechanical control engineering, and in particular relates to an AC excitation synchronous motor control device and method. Background technique [0002] The existing frequency conversion speed regulation system basically uses the frequency converter to act on the stator end of the AC motor, not only to provide the active current for the motor to run, but also to provide the excitation current to maintain the magnetic field, so the capacity of the frequency converter must be greater than or equal to the capacity of the motor. First, the capacity selection, withstand voltage and current rating of all components such as switching tubes, capacitors, reactors, and even wires used in the inverter must be large enough to match the motor, especially in some megawatt systems The series connection of a large number of switching devices is required to realize the control of the motor, resulting in high cost of the freq...

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Problems solved by technology

[0002] The existing frequency conversion speed regulation system basically uses the frequency converter to act on the stator end of the AC motor, not only to provide the active current for the motor to run, but also to provide the excitation current to maintain the magnetic field, so the capacity of the frequency converter must be greater than or equal to the capacity of the motor. First, the capacity selection, withstand voltage and current rating of all components such as switching tubes, capacitors, reactors, and even wires used in the inverter must be large enough to match the motor, especially in some megawatt systems A large number of switching devices need to be connected in series to realize the control of the motor, resulting in a high cost of the inverter

The excitation efficiency of the existing AC asynchronous motor is too low, which wastes energy; the AC synchronous motor requires an independent excitation unit or an expensive permanent magnet, which greatly increases the cost of the system

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