Cable Compensation Circuit for Power Supply Voltage Drop
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Solution Overview
Problem
Voltage drops in cables connected between a power supply and a battery become significant when the load current increases, leading to a decrease in the voltage supplied to the battery, which is not adequately compensated by existing technologies.
Innovation Solution
A cable compensation circuit that includes a sensing RC filter to generate a sense voltage based on diode current and an averaging RC filter to generate an average voltage, which are used to control the power switch and feedback circuit to precisely reflect the increase in load current, thereby compensating for voltage drops in the cable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the output current of the charger is increased to meet high load demands, then the power delivery capability is improved, but the voltage drop in the cable increases causing the battery voltage to decrease
Solution Approach 1:
The patent applies preliminary action by generating a compensation voltage in advance based on the detected cable voltage drop. The system calculates the expected voltage drop using the cable resistance and load current, then generates a compensation voltage signal before the actual charging occurs. This pre-calculated compensation voltage is added to the charger output voltage to counteract the impending voltage drop, ensuring stable battery voltage even at high power delivery levels.
2Device complexity
If a simple voltage control method is used without considering cable effects, then the device complexity is reduced, but the voltage supplied to the battery becomes inaccurate
Solution Approach 1:
The patent implements feedback by continuously monitoring the load current and calculating the cable voltage drop in real-time. The system measures the actual load current flowing through the cable, uses this information to compute the voltage drop (V=IR), and adjusts the compensation voltage accordingly. This closed-loop feedback mechanism ensures accurate battery voltage control without requiring complex hardware, as it uses simple current sensing and computational adjustment.
3Device complexity
If existing compensation methods are used that do not account for diode current characteristics, then the circuit design is simplified, but the compensation accuracy decreases under heavy load conditions
Solution Approach 1:
The patent applies local quality by specifically addressing the diode current characteristics in the rectifier circuit. Instead of using a generic compensation approach, the system calculates the voltage drop contribution from the diode based on its forward voltage characteristics and the rectified current waveform. This localized consideration of diode behavior allows for more accurate compensation of the total voltage drop, particularly under heavy load conditions where diode losses become significant.
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 solution effectively compensates for increased power consumption in cables due to higher load currents by accurately reflecting the load current variation, ensuring that the battery receives a stable voltage.
Implementation Method 1
a sensing RC filter configured to generate a sense voltage that depends on a diode current by filtering the voltage of the node
Implementation Method 2
a sensing RC filter configured to generate a sense voltage that depends on a diode current by filtering the voltage of the node
Implementation Method 3
an averaging RC filter configured to generate an average voltage by averaging the sense voltage
Implementation Method 4
an averaging RC filter configured to generate an average voltage by averaging the sense voltage
Data Source
AI summary
A cable compensation circuit compensates a voltage drop in a cable coupled between a power supply and a load. The cable compensation circuit includes: a node where a voltage that depends on an input voltage of the power supply during a turn-on period of a power switch of the power supply and depends on an output voltage of the power supply during a turn-off period of the power switch is generated; a sensing RC filter generating a sense voltage that depends on a diode current by filtering the voltage of the node; and an averaging RC filter generating an average voltage by averaging the sense voltage.