Variable Speed Accelerator Startup Control via Generator Mode
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Solution Overview
Problem
In variable speed accelerators with constant and variable speed electric motors and a planetary gear transmission device, the load torque at startup is high, necessitating a larger constant speed electric motor to match the increased torque, which is inefficient.
Innovation Solution
The variable speed accelerator operates in generator mode at startup to reduce torque transfer from the variable speed electric motor, allowing the constant speed electric motor to reach rated speed with reduced load torque, and then shifts to motor mode to increase torque transfer, thereby reducing the capacity requirements of the constant speed electric motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the constant speed electric motor capacity is increased to match the high load torque at startup, then the startup performance is improved, but the device size and cost increase
Solution Approach 1:
The invention dynamically switches the variable speed electric motor between motor mode and generator mode during startup. In motor mode, it assists the constant speed electric motor to overcome high load torque. In generator mode, it acts as a brake to reduce load torque when the constant speed motor reaches rated speed. This dynamic operation allows the constant speed motor to be sized for normal operation rather than peak startup torque, reducing its capacity requirements.
Solution Approach 2:
The invention changes the operational parameter of the variable speed electric motor from purely motor mode to a dual mode (motor and generator). By controlling the motor mode time and generator mode time, the system optimizes the balance between overcoming startup torque and reducing load on the constant speed motor, thereby reducing the required capacity of the constant speed electric motor.
2Force
If the variable speed electric motor operates in motor mode during startup, then the startup torque is increased, but the load torque on the driven object becomes excessively large
Solution Approach 1:
The invention uses periodic switching between motor mode and generator mode for the variable speed electric motor. The motor mode time and generator mode time are controlled in cycles, allowing the system to periodically assist startup torque and then periodically reduce load torque. This periodic action prevents excessive continuous load torque on the driven object while still achieving effective startup.
Solution Approach 2:
The invention converts the variable speed electric motor into a generator during part of the startup process. Instead of the motor continuously driving the load (causing excessive torque), the generator mode converts the motor's rotational energy into electrical energy, creating a braking effect that reduces the load torque on the driven object. This transforms a potential harmful effect (excessive torque) into a beneficial one (torque reduction).
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 effectively reduces the load torque on the driven object at startup, allowing for a smaller constant speed electric motor and minimizing energy consumption during startup.
Implementation Method 1
the variable speed electric motor is shifted to the generator mode
Implementation Method 2
a constant speed electric motor and a variable speed electric motor which differ from each other in speed
Data Source
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AI summary
A starting method of a variable speed accelerator, which includes an electric device for generating rotational driving force and a transmission device for changing a speed of the rotational driving force generated by the electric device and transmits the changed rotational driving force to an object to be driven, the starting method includes: a constant speed electric motor starting step of starting a constant speed electric motor and gradually increasing a number of rotations in a first direction of a constant speed rotor and an internal gear; and a generator mode operating step of operating a variable speed electric motor in a generator mode and rotating a planetary gear carrier in the first direction, wherein the transmission device is a planetary gear transmission device, and wherein the electric device comprises: the constant speed electric motor which has the constant speed rotor for rotating the internal gear carrier shaft of the transmission device in the first direction; and the variable speed electric motor which has a variable speed rotor connected to the planetary gear carrier shaft of the transmission device, serves as a generator in a generator mode in which the planetary gear carrier shaft is rotated in the first direction, and serves as an electric motor in an electric motor mode in which the planetary gear carrier shaft is rotated in a second direction opposite to the first direction.