Two-Wire Loop Interface Circuit for Variable-Voltage Power Control
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Solution Overview
Problem
Existing loop-powered field devices, such as radar level gauges, face challenges in achieving sufficient power supply from a two-wire current loop, especially under varying conditions, as the power management configurations in prior art are inefficient in utilizing the available power, leading to inadequate energy delivery for high-power demands during measurement processes.
Innovation Solution
A loop-powered field device with a switching converter that regulates input voltage across the current control circuitry, allowing voltage variation in response to loop voltage changes, coupled with an energy storage device and a shunt regulator, enables efficient power utilization and temporary energy storage to meet operational demands, while maintaining rapid and accurate control of the measurement signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a regulated converter is used to provide fixed input voltage to the power management circuitry, then the measurement signal control is simplified, but the available power from the two-wire current loop is not fully utilized under varying loop voltage conditions
Solution Approach 1:
The patent applies dynamics by making the input voltage to the power management circuitry variable rather than fixed. The controllable voltage source adjusts the input voltage dynamically based on the actual loop voltage, enabling the system to adapt to varying power conditions and maximize power utilization while maintaining proper measurement signal control.
2Speed
If the clock frequency of the processor is increased during signal processing, then high speed calculations are enabled, but the power demand increases significantly
Solution Approach 1:
The system dynamically adjusts the operating conditions by varying the input voltage to the power management circuitry based on the processing stage. During high-power需求的 processing operations, the voltage is adjusted to enable sufficient power delivery to support increased clock frequencies, while during lower-power stages, the voltage is reduced to minimize power consumption.
3Reliability
If a controllable current source and regulated converter are connected in series along the two-wire control loop, then the measurement signal can be provided and power converted, but the configuration cannot provide sufficient power under all operating situations
Solution Approach 1:
The patent changes the key parameter of input voltage from a fixed regulated value to a variable value that tracks the loop voltage. The controllable voltage source adjusts its output voltage in response to loop voltage variations, enabling the power management circuitry to receive appropriate voltage levels under different operating conditions and thereby providing sufficient power across all situations.
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 configuration allows for the effective use of a larger portion of the available power on the two-wire current loop for powering the field device, ensuring reliable operation and efficient communication of measurement signals, even under conditions of varying loop voltage, thereby addressing the limitations of prior art power supply methods.
Implementation Method 1
the converter (15) converts an input voltage across said input terminals to an output voltage across output terminals
Implementation Method 2
an energy storage device and a shunt regulator, enables efficient power utilization and temporary energy storage
Data Source
Figure 1~3c
Figure 4
AI summary
A loop-powered field device for determining a process variable and providing a measurement signal indicative of the process variable to a remote location via a two-wire current loop, the loop-powered field device comprising: a measurement device for determining the process variable; and loop interface circuitry for providing the measurement signal to the two-wire current loop and for providing power from the two-wire current loop to the measurement device. The loop interface circuitry comprises: current control circuitry connected to the two-wire current loop and the measurement device, the current control circuitry being controllable by the measurement device to provide the measurement signal to the two-wire current loop; a first converter having inputs connected to the two-wire current loop in series with the current control circuitry, and an output for providing power to the measurement device; and voltage regulation circuitry for regulating a voltage across the current control circuitry towards a desired voltage, by controlling an input voltage across the inputs of the first converter.