Motor Speed Control to Stabilize DC Bus Voltage Under Fluctuating Load
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Solution Overview
Problem
Existing electric drive apparatuses for transport refrigeration systems face challenges in maintaining stable voltage on the DC bus due to fluctuations in the mechanical load, leading to inefficient power management.
Innovation Solution
A method of operating a motor coupled to a mechanical load, which involves determining a fluctuating speed demand to reduce variations in total power drawn or provided by the motor, and controlling the motor based on a rotary component speed reference value derived from this demand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the motor operates with variable mechanical load, then the motor can adapt to different operating conditions, but the DC bus voltage experiences large fluctuations
Solution Approach 1:
The controller preemptively adjusts the motor speed reference value based on detected torque fluctuations before they cause significant power variations. By calculating the fluctuating component of torque and determining a compensating speed adjustment in advance, the system prevents DC bus voltage fluctuations rather than merely reacting to them.
Solution Approach 2:
The system continuously monitors torque, speed, and power parameters, and uses this feedback to dynamically adjust the motor speed reference value. The controller calculates the fluctuating torque component, determines the appropriate speed compensation, and applies it to maintain stable power consumption, creating a closed-loop control system that actively stabilizes DC bus voltage.
2Stability of the object's composition
If large electrical energy storage devices are added to stabilize DC bus voltage, then voltage stability improves, but device complexity and cost increase
Solution Approach 1:
The patent replaces the need for large electrical energy storage devices (capacitors or batteries) with a control-based solution. By using the motor's own inertia and implementing intelligent speed control that anticipates and compensates for torque fluctuations, the system achieves voltage stabilization through control algorithms rather than additional hardware components.
Solution Approach 2:
The motor system uses its own rotational inertia and control capabilities to stabilize the DC bus voltage, rather than relying on external energy storage devices. The controller leverages the existing motor parameters (inertia, torque characteristics) to generate the compensating speed adjustments needed to maintain stable power consumption and voltage.
Data Source
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AI summary
The present disclosure relates to a method 300 of operating a motor 230 having a rotary component 234 coupled to a mechanical load 240. The method 300 comprises: determining 310 a fluctuating speed demand corresponding to a temporally varying component of a speed of the rotary component 234; determining 330 a rotary component speed reference value based on the fluctuating speed demand; and controlling 340 the motor 230 in accordance with the rotary component speed reference value. The fluctuating speed demand is determined so as to reduce variations in a total power drawn or provided by the motor 230 in use.