Elevator Rectifier Bridge Emergency Drive Control
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Solution Overview
Problem
Elevators lack effective automatic and manual emergency drive systems to safely release trapped passengers in case of power failures, with existing solutions often relying on complex and unreliable components.
Innovation Solution
A rescue drive system that utilizes a manual rescue drive panel, a backup power supply, and an integrated emergency control to precharge the DC link voltage, allowing both automatic and manual emergency operations by controlling the elevator brakes and motor, with enhanced safety features like motion sensors and authorization mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a backup power supply is used for emergency drive operation, then the elevator can perform automatic and manual emergency drives to release trapped passengers, but the system complexity increases due to additional components like switches, boost circuits, and control mechanisms
Solution Approach 1:
The rectifier bridge is designed to perform multiple functions: normal rectification during regular operation and boost circuit operation during emergency drives. By making the rectifier bridge universal, the patent eliminates the need for separate boost circuit components, thereby reducing system complexity while maintaining emergency drive capability. The same semiconductor switches and inductors are used for both normal and emergency operations.
Solution Approach 2:
The patent merges the emergency drive control functionality into the existing controller rather than using a separate emergency control device. The controller integrates the emergency control logic, and the brake release control is also integrated into the same controller, consolidating multiple control functions into a single device and reducing overall system complexity.
2Loss of energy
If the rectifier bridge is controlled via semiconductor switches to enable generator mode refeeding, then energy efficiency improves by returning electricity to mains, but the control complexity and switching losses increase
Solution Approach 1:
The rectifier bridge with controllable semiconductor switches serves dual purposes: during motor mode it rectifies mains power to drive the elevator motor, and during generator mode it functions as an active rectifier that feeds energy back to the mains. This multi-functionality allows energy recovery without requiring separate circuitry, maintaining simplicity while achieving energy efficiency.
3Reliability
If motion sensors and speed threshold monitoring are added to emergency control, then safety during manual rescue drive is improved, but the device complexity and cost increase
Solution Approach 1:
The emergency control system utilizes the existing motion sensor and controller infrastructure already present in the elevator for normal operation. The controller automatically monitors car speed and compares it against predefined thresholds during emergency drives, triggering brake activation without requiring separate dedicated sensing or control hardware. This self-service approach leverages existing resources to provide safety functionality.
4Power
If the DC link is precharged from backup battery via boost activity of semiconductor switches, then emergency drive operation becomes possible with limited power, but the switching losses and heat generation increase
Solution Approach 1:
The semiconductor switches in the rectifier bridge perform dual functions: during normal operation they control power rectification and flow, and during emergency precharging they operate as boost switches to elevate the DC link voltage from the backup battery. This multi-functionality allows the system to achieve high voltage output without requiring dedicated boost circuitry, though switching losses do occur during the precharge phase.
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
Enables reliable and safe automatic or manual emergency drives to release passengers by using existing components for both modes, ensuring high safety levels and minimizing hardware requirements, with the ability to initiate rescue operations even in undefined elevator states.
Implementation Method 1
the rectifier bridge starts to operate as a boost circuit by modulating the low-side igbt transistor of the corresponding rectifier bridge phase, such that the DC link voltage starts to raise
Data Source
AI summary
An elevator includes an elevator motor; a motor drive for the elevator motor having a frequency converter including a rectifier bridge, an inverter bridge and a DC link in between, which frequency converter is controlled via a controller, the rectifier bridge being connected to AC mains via three feed lines including chokes, and the rectifier bridge being realised via controllable semiconductor switches; a contactor being located between the feed lines and AC mains; and a backup power supply at least for emergency drive operation. An emergency control is associated with the motor drive, which emergency control is configured to perform an automatic emergency drive. The emergency control is connected to a manual drive circuit having a manual drive switch for a manual rescue drive. The elevator includes a motion sensor connected to the emergency control, whereby the emergency control is configured to activate a brake and/or gripping device of the elevator in case the car speed during a manual rescue drive exceeds a predetermined threshold value.