Elevator Motor Power Supply Control via Inductive Damping
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Solution Overview
Problem
Existing elevator systems require expensive switch contacts to disconnect the motor from the drive when safety conditions are not met, necessitating periodic inspection and maintenance, and these systems lack rapid power recharging capabilities to minimize delays between elevator runs.
Innovation Solution
A power supply assembly with a bus capacitor, an inductor, and a restrictive circuit portion that includes resistance to dampen resonance effects, allowing the bus capacitor to charge quickly and eliminating the need for switch contacts between the drive and motor, using a switch on the input side to control power supply and rapidly recharge the DC bus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switch contacts are used to disconnect the motor from the drive when safety conditions are not met, then power disconnection is achieved, but the system becomes more expensive and requires periodic inspection and maintenance
Solution Approach 1:
The patent removes the switch contacts from the system entirely and replaces them with a control circuit that opens the IGBTs (insulated-gate bipolar transistors) in the inverter bridge. This extraction eliminates the need for mechanical switch contacts while achieving the same power disconnection function through electronic control, thereby reducing device complexity and maintenance requirements while maintaining reliability
Solution Approach 2:
The patent substitutes the mechanical switch contacts with an electronic control system that manipulates the IGBT switches in the inverter. Instead of using mechanical contacts to disconnect power, the system uses electronic switching of semiconductor devices controlled by a microprocessor, replacing a mechanical system with an electronic one to eliminate wear, contact arcing, and maintenance needs
2Reliability
If switch contacts are used to disconnect power to the motor, then safety requirements are met, but additional cost is introduced through expensive contacts and maintenance
Solution Approach 1:
The patent extracts the switch contacts from the system and replaces their function with electronic control of the IGBTs in the inverter bridge. This elimination of expensive mechanical components directly reduces manufacturing cost while maintaining the ability to meet safety requirements through electronic power disconnection
Solution Approach 2:
The patent replaces expensive, maintenance-intensive switch contacts with inexpensive semiconductor IGBTs and control circuitry. The electronic components are much cheaper to manufacture and have no wear parts, eliminating the need for periodic inspection and maintenance, thereby significantly reducing the total cost of ownership
3Reliability
If traditional power supply control is used with switch contacts, then power disconnection is achieved, but delays occur between elevator runs due to slower recharging
Solution Approach 1:
The patent replaces mechanical switch contacts with electronic IGBT control, enabling much faster switching speeds. This electronic control system can recharge the DC bus capacitor and restore power to the motor within 10-100 milliseconds, compared to the slower mechanical contact system, thereby minimizing delays between elevator runs and improving productivity
Solution Approach 2:
The patent implements dynamic control of the IGBT switches through a microprocessor that can rapidly change the switching state based on safety conditions. This dynamic electronic control allows for fast recharging of the DC bus and quick restoration of motor power, enabling the system to respond rapidly to changing conditions and minimize idle time between operations
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 solution reduces costs, simplifies the design, and enables rapid recharging of the DC bus within 10-100 milliseconds, minimizing delays and eliminating the need for expensive switch contacts, thus enhancing the efficiency and reliability of elevator operations.
Implementation Method 1
an inductor having an impedance that limits an amount of current supplied to the bus capacitor during an initial charging of the bus capacitor
Implementation Method 2
a restrictive circuit portion associated with the input side for dampening a resonance effect of the inductor
Implementation Method 3
The restrictive circuit portion has a resistance that allows the bus capacitor to charge quickly
Data Source
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AI summary
An exemplary power supply assembly includes a drive device having a bus capacitor. A switch associated with an input side of the drive device selectively connects the drive device to a power supply. An inductor has an impedance that limits an amount of current supplied to the bus capacitor during an initial charging of the bus capacitor when the switch connects the input side of the drive device to the power supply. A restrictive circuit portion dampens a resonance effect of the inductor. The restrictive circuit portion has a resistance that allows the bus capacitor to charge quickly. The impedance of the inductor has a more significant effect on how quickly the bus capacitor charges than an effect of the resistance. A dampening factor of the restrictive circuit controls a voltage of the bus capacitor during the charging of the bus capacitor.