Variable Speed Drive Deceleration Control During Power Outage
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Solution Overview
Problem
Existing variable speed drive systems for electric motors are not adequately adaptable to specific applications, leading to suboptimal deceleration profiles during power outages, as they do not account for the mechanical characteristics of the motor and its load.
Innovation Solution
A control method that determines and manages Joule-effect losses in the electric motor and variable speed drive by adjusting the flux reference, allowing for dynamic adaptation of the deceleration ramp based on available energy and torque limitations, thereby optimizing the deceleration process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a pre-stored deceleration profile is used during power outage, then the control procedure is simple, but the deceleration ramp cannot be adapted to specific application requirements
Solution Approach 1:
The patent transforms the static, pre-stored deceleration profile into a dynamic control system that adapts in real-time. The control procedure continuously monitors DC bus voltage and dynamically adjusts the deceleration ramp parameters based on available energy levels, making the system adaptable to different applications without requiring complex pre-programming for each scenario.
Solution Approach 2:
The invention changes the control parameters dynamically during the deceleration process. By monitoring the DC bus voltage and comparing it against reference values, the system adjusts flux reference and torque limitation parameters in real-time, enabling adaptation of the deceleration ramp to match available energy and mechanical constraints without increasing overall system complexity.
2Productivity
If the deceleration ramp is made steeper to stop the motor faster, then productivity increases, but Joule-effect losses increase and may exceed available energy
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors the DC bus voltage during deceleration. By comparing the measured voltage against reference values representing available energy, the system adjusts the deceleration ramp in real-time. This feedback loop ensures that the motor stops as quickly as possible without exceeding the energy available in the DC bus, thereby maximizing productivity while preventing excessive Joule-effect losses.
Solution Approach 2:
The control procedure applies partial torque limitation during deceleration based on available energy. Instead of applying full torque limitation from the start, the system gradually increases limitation as DC bus voltage decreases, allowing for faster initial deceleration when energy is abundant while preventing energy exhaustion when voltage drops, thus optimizing the balance between deceleration speed and energy consumption.
3Loss of energy
If torque limitation is applied to reduce Joule-effect losses, then energy management improves, but deceleration time increases
Solution Approach 1:
The patent applies torque limitation in a periodic or staged manner rather than continuously. The control procedure monitors DC bus voltage and applies torque limitation only when voltage drops below certain thresholds, allowing for periods of higher torque when energy is available. This periodic application of torque limitation reduces average Joule-effect losses while maintaining acceptable deceleration times by intensifying deceleration effort during high-energy periods.
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 enables the electric motor to decelerate as quickly as allowed by the mechanical system, ensuring efficient energy management and compliance with the mechanical characteristics of the motor, even during power outages.
Implementation Method 1
a step of determining the Joule-effect losses to be applied to the electric motor and to the variable speed drive according to a deceleration ramp to be applied to the electric motor during an electrical power outage
Data Source
AI summary
The invention relates to a method of control implemented in a variable speed drive for controlling the deceleration of an electric motor (M) in the case of electrical power outage. The method of control comprises:a step of determining the Joule-effect losses to be applied to the electric motor (M) and to the variable speed drive according to a deceleration ramp to be applied to the electric motor (M) during an electrical power outage,a step of determining the flux reference (φref) as a function of the said Joule-effect losses to be applied to the electric motor (M) and to the variable speed drive.