Current Control Device for Unknown Load Characteristics
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Solution Overview
Problem
Current control devices for loads with unknown current-vs.-voltage characteristics suffer from significant energy losses due to the use of resistors for regulating current.
Innovation Solution
A method involving a power converter, a load, and a resistor, where a transfer function is determined and updated using a calibration process to minimize energy losses by eliminating the need for a resistor in standard operating mode, utilizing a microprocessor to apply and adjust voltages and currents based on sampled values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a resistor is used to regulate current in the load, then current control is achieved, but energy loss increases significantly
Solution Approach 1:
The patent extracts and removes the resistor from the standard operating configuration. During calibration, the resistor is temporarily used to characterize the load, but in normal operation, the load is disconnected from the resistor. This eliminates the continuous energy loss while preserving current control capability through the calibrated transfer function stored in memory.
Solution Approach 2:
The patent performs preliminary calibration action during which the resistor is used to establish the transfer function characterizing the load's current-voltage relationship. This preliminary characterization allows the system to operate without the resistor afterward, as the calibration data enables accurate current control through voltage adjustment alone.
2Measurement precision
If the resistor value is increased to enhance accuracy, then measurement precision improves, but energy loss increases
Solution Approach 1:
The system performs preliminary calibration to capture the precise current-voltage characteristics of the load. This pre-acquired accuracy information is stored and reused during normal operation, eliminating the need for a high-value resistor that would cause energy loss while maintaining measurement precision through the stored transfer function.
Solution Approach 2:
The patent creates a digital copy of the load's current-voltage characteristic through the transfer function obtained during calibration. This mathematical model replaces the physical resistor, providing the same accuracy function without the energy dissipation penalty of a high-value resistor.
3Loss of energy
If a transfer function calibration process is implemented, then energy efficiency improves, but device complexity increases
Solution Approach 1:
The system performs self-calibration by automatically characterizing its own load during an initial phase. The microprocessor controls the calibration process, stores the resulting transfer function in memory, and uses this self-acquired information for efficient operation, eliminating the need for external calibration equipment or complex ongoing calibration procedures.
Solution Approach 2:
The patent replaces the mechanical/resistive current control method with an electronic/software-based transfer function approach. The calibration process uses software algorithms to characterize the load, and the resulting digital transfer function replaces physical resistor-based control, reducing ongoing complexity while improving efficiency.
Data Source
AI summary
A method of controlling a current flowing through a load including the steps of: applying a first transfer function representative of the load to a first voltage to obtain a second voltage; applying the second voltage to a first terminal of a circuit for generating the current; sampling a third voltage between first and second terminals of the load; comparing the third voltage with the second voltage; and determining the current to be supplied to the load according to the result of the comparison.