Elevator Drive Adjustment Device for Voltage Reduction
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Solution Overview
Problem
Elevator operations are disrupted by voltage reductions or outages in the electricity network, limiting the maximum speed of electric motors due to constraints in power supply voltage, leading to unnecessary breaks and reduced transport capacity.
Innovation Solution
An adjustment device that controls the electric drive of an elevator by regulating the power supply apparatus and speed of the motor, allowing operation closer to the maximum output voltage, continuing operation during voltage reductions by interrupting the speed regulator and limiting the voltage reference vector, and resuming when conditions allow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the speed of rotation of the rotor is increased to improve transport capacity and reduce door-to-door time, then the supply voltage required by the motor increases, but the maximum output voltage of the power supply apparatus is exceeded, causing operational breaks during voltage reductions
Solution Approach 1:
The patent implements dynamic speed regulation by interrupting the speed regulator operation when maximum output voltage is reached and resuming it when voltage conditions improve. This dynamic adjustment allows the system to adapt to changing voltage conditions in the electricity network, maintaining operational continuity while maximizing transport capacity during favorable conditions
Solution Approach 2:
The system changes the operating parameters of the motor by adjusting the speed reference based on voltage conditions. When voltage is sufficient, the motor operates at higher speeds for improved productivity; when voltage is limited, the speed is reduced to stay within the maximum output voltage capability of the power supply apparatus, preventing operational breaks
2Productivity
If the rated speed of the elevator is selected to maximize transport capacity, then the speed operates close to the maximum voltage limit, but voltage reductions in the electricity network cause unnecessary breaks in operation
Solution Approach 1:
The patent employs feedback control by continuously monitoring the output voltage of the power supply apparatus and using this information to control the operation of the speed regulator. When the output voltage approaches the maximum value, the feedback mechanism interrupts the speed regulator to prevent voltage exceedance. When voltage conditions improve, the feedback system resumes speed regulation, ensuring smooth operation without unnecessary breaks
3Reliability
If a voltage margin is maintained between the output voltage of the frequency converter and the supply voltage of the motor, then operational breaks during voltage reductions are prevented, but the elevator speed is limited below the maximum possible value
Solution Approach 1:
Instead of maintaining a fixed voltage margin, the patent dynamically adjusts the operating point based on real-time voltage conditions. By monitoring when the maximum output voltage is reached and temporarily interrupting speed regulation only at that specific threshold, the system eliminates the need for a continuous conservative voltage margin while preventing operational breaks, thereby maximizing elevator speed during favorable voltage conditions
Data Source
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AI summary
The invention relates to an adjustment device (1) for controlling the electric drive (2) of an elevator in connection with a voltage reduction of the supplying network. The electric drive of an elevator comprises an electric motor (3) and a power supply apparatus (4) of the electric motor for adjusting the supply voltage of the electric motor. The adjustment device comprises means (5, 6, 7) for controlling the power supply apparatus (4) of the electric motor and also a speed regulator (8) for adjusting the speed of the electric motor. The adjustment device (1) is arranged to determine the output voltage (9) of the power supply apparatus of the electric motor in relation to the permitted maximum value of the output voltage, and the adjustment device (1) is arranged to interrupt the operation of the speed regulator (8) but to continue the operation of the power supply apparatus (4) of the electric motor when the output voltage (9) of the power supply apparatus of the electric motor reaches the permitted maximum value.