Power Supply Voltage Drop Compensation via Load Current Feedback
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Solution Overview
Problem
Conventional power supply devices with fixed output voltage struggle to maintain a stable voltage applied to loads as load current increases, leading to voltage drops due to cable impedance, especially when the output voltage is changeable.
Innovation Solution
A power supply device with a detection unit, setting unit, and correction unit that adjusts the output voltage based on load current, ensuring the applied voltage remains constant by increasing the detected voltage value in accordance with the load current, independent of changes in the instruction value for the output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the output voltage of a power supply device is changed by adjusting the voltage division ratio of voltage dividing resistors, then the output voltage can be adjusted to different values, but the correction value for the output voltage also changes in accordance with the voltage division ratio, causing the voltage applied to the load to decrease
Solution Approach 1:
The patent segments the voltage adjustment function into two independent parts: (1) voltage division circuit for setting output voltage level, and (2) correction circuit for compensating cable voltage drop. The correction circuit uses a separate correction resistor connected to the adjustment terminal, independent of the voltage dividing resistors. This allows the output voltage to be adjusted while maintaining a constant correction value, resolving the contradiction between voltage adjustability and applied voltage stability.
Solution Approach 2:
The patent introduces an adjustment terminal as an intermediary element that receives correction current from the correction resistor. This terminal acts as a mediator between the voltage division circuit and the output stage, allowing independent control of the correction amount. The correction current flows through this intermediary to adjust the output voltage without being affected by changes in the voltage division ratio, thus maintaining stable applied voltage.
2Reliability
If a stabilization circuit with load current-dependent output voltage correction is applied to a power supply device with changeable output voltage, then the voltage applied to the load can be kept fixed, but changing the voltage division ratio to adjust output voltage causes the correction value to change accordingly, reducing the applied voltage
Solution Approach 1:
The patent separates the voltage correction function from the voltage division function. The correction resistor is connected to the adjustment terminal independently of the voltage dividing resistors. This segmentation allows the correction value to remain constant while the output voltage is adjusted by changing the voltage division ratio, resolving the contradiction between applied voltage stability and output voltage adjustability.
Solution Approach 2:
The adjustment terminal serves multiple functions: it receives the correction current from the correction resistor for output voltage adjustment, and it allows independent control of the correction amount regardless of the voltage division ratio. This multi-functionality enables the system to maintain stable applied voltage while providing flexible output voltage adjustment.
3Reliability
If the output voltage is increased to compensate for cable impedance and maintain stable applied voltage, then the voltage applied to the load remains constant, but the output voltage of the power supply device increases, leading to increased power loss
Solution Approach 1:
The patent implements a feedback mechanism where the correction resistor is connected between the output terminal and the adjustment terminal. The correction current is derived from the output voltage itself, creating a feedback loop that automatically adjusts the output voltage based on the actual voltage at the adjustment terminal. This feedback ensures that the output voltage is increased only by the exact amount needed to compensate for cable voltage drop, minimizing unnecessary power loss while maintaining stable applied voltage.
Solution Approach 2:
The correction circuit is self-regulating through the feedback mechanism. The correction current automatically adjusts based on the output voltage and cable conditions without requiring external intervention. The system serves itself by using the output voltage to generate the correction current, ensuring minimal power loss while maintaining stable applied voltage across varying load conditions.
Data Source
AI summary
A power supply device for outputting a DC voltage includes: a pair of positive and negative output terminals, a load to which the DC voltage is applied being connected thereto; a detection unit configured to detect a voltage value of the DC voltage output from the output terminals; a setting unit configured to select an instruction value for the DC voltage output from the output terminals from among a plurality of preset instruction values, and set the selected instruction value; and a correction unit configured to increase one of the voltage value detected by the detection unit and the instruction value set by the setting unit, according to an amount by which a current value of a current that flows through the load increases.