Resistive Voltage Sensing Across Isolation Boundaries
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Solution Overview
Problem
Conventional voltage sensors for UL 60950-1 compliant systems are large, expensive, and inaccurate due to the use of transformers, opto-couplers, and Hall effect devices, which fail to meet the requirements of safety and isolation standards.
Innovation Solution
A voltage sensor designed using a resistor network that adheres to UL 60950-1 safety standards by employing a plurality of resistors configured as a voltage divider, ensuring proper clearance and creepage spacing, and limiting current flow to meet isolation requirements, thereby eliminating the need for transformers and opto-couplers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transformers, opto-couplers, or Hall effect devices are used for voltage sensing, then isolation requirements are met, but the device size becomes large, cost increases, and measurement accuracy decreases
Solution Approach 1:
The voltage sensing function is segmented into multiple discrete resistor components arranged in a specific configuration. Instead of using a single integrated transformer or opto-coupler, the solution divides the sensing function across multiple resistive elements that can be individually selected and positioned to meet both electrical and physical requirements.
Solution Approach 2:
The patent replaces electromagnetic mechanisms (transformers, opto-couplers, Hall effect devices) with a purely resistive electrical system. This substitution eliminates the need for magnetic cores, optical components, or complex electromagnetic structures, resulting in a compact, low-cost solution that maintains measurement accuracy while satisfying isolation requirements through proper resistor selection and arrangement.
2Reliability
If transformers, opto-couplers, or Hall effect devices are used for voltage sensing, then isolation requirements are met, but manufacturing cost increases
Solution Approach 1:
The patent employs standard, inexpensive resistor components that can be mass-produced and easily replaced if needed. These discrete resistors are far cheaper than transformers, opto-couplers, or Hall effect devices, while still achieving the required isolation compliance through proper circuit configuration and component selection.
Solution Approach 2:
By replacing expensive electromagnetic and optical components with simple resistive elements, the patent dramatically reduces manufacturing costs. The resistive solution requires no specialized electromagnetic shielding, magnetic materials, or optical assemblies, making it inherently more cost-effective while maintaining functional requirements.
3Reliability
If transformers, opto-couplers, or Hall effect devices are used for voltage sensing, then isolation requirements are met, but measurement accuracy decreases
Solution Approach 1:
The patent applies local quality by selecting resistors with specific characteristics (precision tolerance ratings, low temperature coefficients) for critical positions in the voltage divider network. By optimizing the local properties of individual resistor components rather than relying on the overall performance of a transformer or opto-coupler, the solution achieves high measurement accuracy while maintaining isolation compliance.
Solution Approach 2:
The replacement of electromagnetic sensing mechanisms with a precision resistive voltage divider eliminates sources of error inherent in transformers (magnetic saturation, frequency response issues) and opto-couplers (LED non-linearity, temperature drift). The purely resistive system provides superior measurement accuracy through its simplicity and predictability.
4Volume of moving object
If a resistor network is used for voltage sensing, then device size and cost are reduced, but ensuring compliance with safety isolation standards becomes more difficult
Solution Approach 1:
The resistor network is segmented into multiple discrete components with specific resistance values and power ratings. This segmentation allows each resistor to be individually selected to meet voltage stress requirements and isolation criteria, making compliance verification systematic and straightforward rather than requiring complex integrated components.
Solution Approach 2:
The patent utilizes parameter changes by selecting resistors with specific resistance values, power ratings, and tolerance specifications that collectively achieve the required isolation and accuracy. By carefully controlling these parameters, the solution meets safety standards while maintaining a compact, simple design.
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
The resistor-based voltage sensor is smaller, less costly, and more accurate than conventional methods, providing precise amplitude and phase response while meeting safety and isolation standards, thus enabling efficient voltage measurement across isolation boundaries.
Implementation Method 1
a plurality of resistors configured as a voltage divider
Data Source
AI summary
Methods and apparatus provide for a primary side circuit including one or more voltage nodes; and a monitoring circuit operating to monitor one or more parameters of the primary side circuit, and including at least one sensing circuit and at least one processing circuit within a secondary side circuit, where the sensing circuit includes a resistor network having an input for receiving a first sensed voltage from a first of the voltage nodes of the primary side circuit, traversing an isolation boundary between the primary side circuit and the secondary side circuit while adhering to a safety specification, which includes a primary-secondary isolation requirement, and having an output for providing a first modified sensed voltage to the processing circuit.