Motor Starter with Semiconductor Contactor and Buffer Capacitor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional motor starters with electromechanical contactors fail to disconnect the motor load when semiconductor contactors malfunction, as these faults are not detected, leading to continuous operation of the motor.
Innovation Solution
A motor starter design incorporating a semiconductor contactor with an interface for control signals, an electrical energy storage (buffer capacitor), and programmable control electronics that allows for communication with a motor protection switch, enabling the starter to generate a trigger signal for load disconnection even in case of contactor defects, using existing current flow measuring devices for energy supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If semiconductor contactors are used to replace electromechanical contactors, then mechanical wear is eliminated and switching frequency is increased, but galvanic isolation is lost and short-circuit strength is reduced
Solution Approach 1:
The patent combines a semiconductor contactor with an electromechanical circuit breaker in a hybrid configuration. The semiconductor contactor handles normal switching operations without mechanical wear, while the circuit breaker provides short-circuit protection and galvanic isolation. This merging allows the system to benefit from both technologies: the semiconductor contactor's high switching durability and the circuit breaker's short-circuit strength.
2Speed
If semiconductor contactors are used, then switching speed is increased and mechanical wear is eliminated, but power loss increases and heat dissipation requirements increase
Solution Approach 1:
The patent incorporates a buffer capacitor that is pre-charged during normal operation. In the event of a semiconductor contactor failure, this pre-charged capacitor immediately provides the energy needed to actuate the circuit breaker without waiting for external power supply. This preliminary action ensures rapid response to failures while allowing the semiconductor contactor to operate efficiently during normal conditions.
3Ease of manufacture
If conventional motor protection switch-contactor combinations are used, then manufacturing cost is reduced, but fault detection capability is insufficient and separation cannot be guaranteed in case of contactor defects
Solution Approach 1:
The patent implements a feedback mechanism where the circuit breaker monitors the status of the semiconductor contactor through control lines. When a fault is detected in the semiconductor contactor, the circuit breaker receives this information and automatically actuates to separate the load. This feedback loop ensures reliable fault detection and separation while maintaining a relatively simple and cost-effective design.
4Volume of moving object
If semiconductor contactors are used in compact form factors, then space requirements are reduced, but heat dissipation becomes more challenging
Solution Approach 1:
The patent uses the circuit breaker as an intermediary protective device that can be mounted on the semiconductor contactor housing. This arrangement allows the heat-generating semiconductor components to be housed in a compact form factor while the circuit breaker provides thermal management and protection. The circuit breaker acts as a mediator that handles the thermal and protective functions, allowing the semiconductor contactor to maintain a small footprint.
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 safe disconnection of the motor load during contactor defects, reducing the risk of permanent operation and allowing for compact motor starter designs with reduced space requirements and efficient heat dissipation.
Implementation Method 1
The contactor has an electrical energy storage, in particular a buffer capacitor, which is charged by the switching signal
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a motor starter having a motor circuit breaker (10) which has an electronic tripping device (14), and having a contactor (12) which is correspondingly interconnected to the motor circuit breaker (10) for forming the motor starter. According to the invention, at least one control line (16, 16') is provided between the motor circuit breaker (10) and the contactor (12), a control signal which is generated depending on a switching signal (18) for switching the contactor (12) being transmitted from the contactor (12) to the electronic tripping device (14) via the said control line, and the electronic tripping device (14) being designed in such a way as to generate a tripping signal (22) for switching off the current flow across the switching contact or the switching contacts (20) of the motor circuit breaker (10) depending on the control signal and current flow across one or more switching contacts (20) of the motor circuit breaker (10).