Intelligent Switch Capacitor with Electronic Thermal Protection
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Solution Overview
Problem
Conventional power capacitors and capacitor switches are separately produced, leading to mismatched components, high power consumption, inadequate protection against high-order harmonic resonance, slow switching, and unrecoverable thermal expansion mechanisms, which result in inefficient and costly reactive compensation in power grids.
Innovation Solution
An intelligent switch capacitor integrating a capacitor switch, temperature sensor, current measurement module, and harmonic component measurement module with a single-chip microcomputer, magnetic latching relay, and capacitive buck rectifier power supply, allowing for precise, rapid, and adjustable protection against overheating, overcurrent, and harmonic resonance, while reducing power consumption and eliminating the need for discharge resistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional mechanical thermal expansion snap-type explosion-proof mechanism is used, then the capacitor is protected from overheating, but the mechanism is unrecoverable and has high sealing requirements with low response speed
Solution Approach 1:
The patent replaces the mechanical thermal expansion snap-type explosion-proof mechanism with an electronic control system comprising a temperature sensor, microcontroller, and switching device. The temperature sensor detects capacitor temperature in real-time, the microcontroller processes the signal, and the switching device disconnects the capacitor when overheating is detected, eliminating the need for complex mechanical sealing while achieving rapid protective response.
Solution Approach 2:
The intelligent switch capacitor integrates the temperature sensor, control circuit, and switching device within the capacitor itself, enabling the capacitor to autonomously detect its own temperature and trigger protective disconnection without requiring external protection devices. This self-monitoring and self-protection capability eliminates the need for separate external protection mechanisms.
2Ease of operation
If a conventional contactor-type capacitor switch is used, then the capacitor can be disconnected, but the switch has large power consumption around 15W and slow switching speed due to residual voltage
Solution Approach 1:
The patent replaces the conventional contactor-type mechanical switch with an electronic switching device controlled by a microcontroller. This electronic switch eliminates the large power consumption (around 15W) and slow switching speed associated with mechanical contactors, enabling rapid capacitor disconnection without residual voltage issues.
Solution Approach 2:
The patent implements a discharge control mechanism that periodically monitors capacitor voltage and actively manages the discharge process through the electronic switching device, eliminating the persistent residual voltage problem that causes slow switching in conventional systems.
3Reliability
If a discharge resistor is installed inside the conventional power capacitor, then safety specifications are met, but the discharge resistor produces large power consumption exceeding 100 million kilowatts per year
Solution Approach 1:
The patent replaces the passive discharge resistor with an active electronic switching device controlled by a microcontroller. Instead of continuously dissipating energy through resistive heating, the electronic switch actively manages capacitor discharge, significantly reducing power consumption while maintaining safety compliance through controlled energy dissipation.
Solution Approach 2:
The patent implements periodic voltage monitoring and controlled discharge through the electronic switching device, replacing the continuous energy waste of discharge resistors with intermittent, demand-based discharge actions that maintain safety while minimizing energy loss.
4Ease of manufacture
If power capacitors and capacitor switches are produced separately, then manufacturing flexibility is maintained, but matching of different power capacitors with suitable switches is required and assembly is needed
Solution Approach 1:
The patent integrates the capacitor switch, temperature sensor, control circuit, and housing into a single unified intelligent switch capacitor unit. This integration eliminates the need for separate production and matching of capacitors and switches, as well as post-assembly operations, while maintaining manufacturing flexibility through modular design principles.
Solution Approach 2:
The intelligent switch capacitor is designed as a universal integrated unit that combines multiple functions (capacitance, switching, temperature sensing, control) into a single device that can serve different power compensation needs, eliminating the complexity of matching different components while maintaining adaptability.
5Reliability
If a reactor is connected in series in the capacitor circuit to prevent high-order harmonic resonance, then partial protection is achieved, but burnout of the power capacitor still occurs due to resonance
Solution Approach 1:
The patent replaces the passive reactor-based harmonic protection with an active intelligent control system that uses a current measurement module to detect harmonic currents, a communication module to receive control signals, and an electronic switching device to rapidly disconnect the capacitor when harmonic resonance is detected, providing more effective protection against capacitor burnout.
Solution Approach 2:
The patent implements a feedback control system where the current measurement module continuously monitors circuit conditions, the communication module receives control signals, and the switching device responds by disconnecting the capacitor when harmonic resonance is detected, creating a closed-loop protection mechanism that actively prevents capacitor burnout rather than passively mitigating harmonics.
Data Source
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AI summary
The present invention relates to an intelligent switch capacitor, which comprises a shell. The shell is provided with a capacitor core internally. A temperature sensor is arranged on the capacitor core. A top end of the capacitor core is connected to an intelligent switch wiring board. The intelligent switch wiring board is connected to a single chip computer, a capacity-switch, a temperature measurement module, a current measurement module and a current harmonic component measurement module, wherein the capacitor switch is connected to the capacitor core in an inner triangle way. Beneficial effects of the present invention are: 1. A switch and a power capacitor are integrated into a whole, which can implement quick capacity-switching and cutting of the switch; 2. The capacitor has an electronic thermal protection function; 3. Possibilities of capacitor damages and power grid accidents caused by resonance of a PFC capacitor in a power grid system are eliminated completely; 4. A power capacitor loss is reduced.