Capacitive Isolation Barrier for Sigma Delta Modulator
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Solution Overview
Problem
Existing electronic energy meters face challenges with high electrical isolation requirements between phases, leading to increased costs and power consumption due to the use of expensive optocouplers.
Innovation Solution
The implementation of a capacitive isolation barrier in conjunction with a sigma delta modulator provides electrical isolation while reducing complexity and power consumption, allowing for a single-chip front-end with integrated analog-to-digital conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optocouplers are used to establish electrical isolation between phases, then electrical isolation is achieved, but cost and power consumption increase substantially
Solution Approach 1:
The patent replaces the optical isolation mechanism (optocouplers) with an electrical isolation mechanism using isolation amplifiers. These amplifiers provide galvanic isolation between the high-voltage primary side and low-voltage secondary side while maintaining signal transmission, thereby eliminating the need for optocouplers and reducing both cost and power consumption.
Solution Approach 2:
The patent changes the isolation mechanism from optical to electrical domain, using isolation amplifiers that operate in the electrical domain. This parameter change allows for more efficient power consumption characteristics and lower cost implementation while maintaining the required galvanic isolation functionality.
2Reliability
If optocouplers are used to establish electrical isolation between phases, then electrical isolation is achieved, but device complexity increases
Solution Approach 1:
The patent substitutes the complex optical isolation system with a simpler electrical isolation system based on isolation amplifiers. This reduces the number of components required and simplifies the overall circuit architecture while maintaining galvanic isolation functionality.
Solution Approach 2:
The isolation amplifiers serve multiple functions simultaneously: they provide galvanic isolation, amplify the measurement signals, and enable bidirectional communication between primary and secondary sides. This multi-functionality reduces the overall device complexity compared to using separate components for each function.
3Measurement precision
If shunt devices and voltage dividers are coupled directly to electrical lines, then current and voltage measurement is enabled, but exposure to high electrical potentials damages ADCs
Solution Approach 1:
The patent divides the measurement system into two electrically isolated segments: the primary side that interfaces with high-voltage electrical lines and contains the shunt device and voltage dividers, and the secondary side that contains the protected ADCs. Isolation amplifiers provide the interface between these segments, enabling measurement functionality while protecting sensitive components through galvanic isolation.
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 results in a cost-effective and power-efficient electronic energy meter that can measure both voltage and current, offering a cheaper and less complex alternative to traditional solutions.
Implementation Method 1
The capacitive isolation barrier provides electrical isolation and capacitive coupling through the barrier
Implementation Method 2
The voltage drop across the shunt device corresponds to the current through the electrical line
Data Source
AI summary
An electronic energy meter includes a first sigma delta modulator having an electrically isolated digital data output. A power supply stage coupled to a first electrical line provides a supply voltage to the first sigma delta modulator. A shunt device is also coupled to the first electrical line. The first sigma delta modulator is coupled via an input to the shunt device for measuring a current through the first electrical line. The electrically isolated digital output is isolated by a capacitive isolation barrier.