Power Supply Isolation Measurement for Accurate Mains Power
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Solution Overview
Problem
Existing power supply systems struggle to accurately determine power supplied by mains connections due to high voltage and current measurements, making it complicated to assess power efficiently.
Innovation Solution
A power supply system with an input terminal, output terminal, power converter, measurement circuit, and control unit that determines mains voltage and current on the load side, using a loss model to calculate supply power based on load power and loss power, with an isolation transformer for magnetic coupling and measurement on secondary circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage and current are measured right after the output of the mains connection to determine power, then measurement accuracy is improved, but device complexity and difficulty of measurement increase due to high voltage and current values
Solution Approach 1:
The patent introduces a current transformer as an intermediary device to measure current indirectly. Instead of measuring high current directly, the current transformer converts it to a proportional, measurable signal. This resolves the contradiction by maintaining measurement accuracy through the transformer's precise turns ratio while reducing device complexity and measurement difficulty through signal transformation.
Solution Approach 2:
The patent replaces direct electrical measurement of high voltage and current with a combination of voltage division (using resistors) and current transformation (using current transformer). This substitution approach measures equivalent, lower-value signals that are easier to handle while maintaining measurement accuracy through known transformation ratios, thus reducing device complexity.
2Measurement precision
If direct measurement of mains voltage and current is performed, then power determination accuracy is improved, but ease of operation deteriorates due to safety risks and measurement complexity
Solution Approach 1:
The current transformer acts as an intermediary that provides galvanic isolation between the high-voltage mains circuit and the measurement circuit. This maintains measurement accuracy through precise transformation ratios while dramatically improving ease of operation by eliminating direct exposure to dangerous high voltages and currents, making the measurement process safer and simpler.
Solution Approach 2:
The patent segments the measurement system into separate functional blocks: voltage measurement (through division), current measurement (through transformation), and power calculation. This segmentation allows each block to operate at safe, low levels while maintaining overall measurement accuracy, thus improving ease of operation without sacrificing precision.
3Measurement precision
If measurement circuit directly interfaces with mains connection, then measurement accuracy is improved, but reliability decreases due to safety hazards and electrical isolation requirements
Solution Approach 1:
The current transformer provides galvanic isolation as an intermediary between the mains connection and the measurement circuit. This maintains measurement accuracy by preserving the proportional relationship between primary and secondary currents while dramatically improving reliability through electrical isolation, eliminating safety hazards from direct mains interfacing.
Solution Approach 2:
The voltage division network using resistors serves as an intermediary that steps down mains voltage to a safe, measurable level. This maintains measurement accuracy through known resistance ratios while improving reliability by preventing direct exposure to dangerous mains voltage, thus ensuring system safety.
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
Provides a practical and accurate method to determine supply power without losing accuracy, enabling efficient power management and detection of quality characteristics like harmonic content and phase-cut dimming.
Implementation Method 1
an isolation transformer having a primary circuit connected to the input terminal and a secondary circuit connected to the output terminal, the secondary circuit being electrically isolated from the primary circuit and magnetically coupled to the primary circuit
Data Source
Figure 1a
Figure 1b
Figure 1c
AI summary
Power supply for powering a load, the power supply comprising an input terminal configured to be connected to an external power supply having a mains voltage, an output terminal configured to be connected to the load, a power converter configured to convert a supply power, received from the external power supply, to a load power for powering the load, a measurement circuit configured to provide a signal representative of the mains voltage, a control unit configured to determine a voltage and a current on a load side of the power converter, and receive the signal from the measurement circuit and to determine the mains voltage based on the signal, and determine the load power supplied on the load side of the power converter, determine a loss power representing the power loss from the external power supply to the load side of the power converter, and determine the supply power.