Refrigeration Inverter Controller Redundant Capacitor Bank
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing controllers with inverters for refrigerating machines face challenges in passing short-circuit tests without risking explosions or fires, particularly due to voltage stress on capacitors, and existing solutions either increase size, reduce thermal dissipation, or require complex and unreliable protection mechanisms, leading to operational interruptions.
Innovation Solution
A controller with a DC bus capacitors bank featuring at least one redundant capacitor, configured in series levels with nominal voltage differences that ensure continued operation even if one capacitor is short-circuited, eliminating the need for encapsulation or complex protection devices, and allowing for a compact and cost-effective design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If encapsulation caps are used to contain capacitor explosions, then safety is improved, but device size increases and thermal dissipation is reduced
Solution Approach 1:
The patent applies preliminary action by providing a redundant capacitor in advance, configured to automatically take over when a capacitor fails. This prevents the need for encapsulation caps while ensuring safety, as the system is prepared beforehand to handle capacitor failures without requiring physical containment structures.
Solution Approach 2:
The patent changes the electrical parameters of the capacitor bank by adding a redundant capacitor with specific capacitance and voltage ratings. This parameter change enables the system to maintain operation after capacitor failure, eliminating the need for encapsulation while preserving safety.
2Reliability
If encapsulation caps are used to contain capacitor explosions, then safety is improved, but thermal dissipation is reduced
Solution Approach 1:
The redundant capacitor is pre-configured in the circuit to provide immediate backup capability. This preliminary arrangement ensures safety through redundancy rather than encapsulation, allowing heat to dissipate naturally without the insulating effect of containment caps.
Solution Approach 2:
The patent extracts the safety function from the physical encapsulation structure and relocates it to the electrical circuit configuration through the redundant capacitor. This separation allows the capacitor bank to operate without restrictive encapsulation, maintaining proper thermal dissipation.
3Reliability
If varistors or gas tubes are used for voltage limiting, then capacitor protection is improved, but device complexity increases
Solution Approach 1:
The redundant capacitor provides self-service protection by automatically taking over when a capacitor fails. This self-acting mechanism eliminates the need for varistors, gas tubes, or other complex protection devices that require additional control circuitry and components.
Solution Approach 2:
The patent extracts the protection function from complex electronic protection devices (varistors, gas tubes) and implements it through a simpler redundant capacitor configuration. This reduces device complexity while maintaining capacitor protection capability.
4Reliability
If a redundant capacitor is added to the capacitors bank, then reliability is improved, but device complexity increases
Solution Approach 1:
The redundant capacitor is merged into the existing capacitor bank structure, sharing the same mounting space and electrical connections. This integration approach minimizes the increase in device complexity while achieving operational continuity through redundancy.
Solution Approach 2:
The redundant capacitor serves multiple functions: it provides backup capacitance, maintains voltage stability, and ensures continuous operation. This multi-functionality justifies the addition without proportionally increasing complexity, as one component achieves multiple protective and operational goals.
Data Source
Figure 1
AI summary
Described is a controller (100) with inverter for refrigerating machines, comprising a DC bus (10) connected to an inverter device (20) and equipped with a capacitors bank (11) comprising a plurality of levels (15) of capacitors (12), for example electrolytic, in series and designed to provide to the inverter device (20) a bus voltage Vcond having a nominal value of not less than an operating voltage Vdc. Each of the levels (15) of capacitors (12) has an electrical capacitance suitable to determine a nominal voltage difference Vci. The capacitors bank (11) being configured in such a way that the sum of the nominal voltage differences Vci of the levels (15) of capacitors (12), subtracted any one of them, is not less than the operating voltage Vdc; the controller (100) being free of an electrical and/or electronic unit configured for interrupting the operation of the controller (100) following a failure and/or short-circuit or malfunction of any one of the capacitors (12).