Control Capacitor Voltage Drop Detection with Buffered Supplies
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Solution Overview
Problem
Existing technologies face challenges in reliably detecting voltage drops, especially in electric machine tools and vehicles, due to the influence of buffer capacitors and the complexity of managing multiple battery packs.
Innovation Solution
A device comprising a control capacitor, a measuring device, and a control device is used to detect voltage drops by evaluating the charging state of the control capacitor, which is connected between the anode and cathode connections. This setup allows for flexible use with different electrical facilities, including those with buffered supply voltages and multiple voltage sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If buffer capacitors are used to minimize overvoltages, then the circuit breakers can operate within their specified range, but the buffer capacitors can temporarily act as an energy source and conceal the removal or malfunction of the battery pack, preventing detection of supply voltage loss
Solution Approach 1:
The control capacitor is charged in advance to a control voltage that corresponds to a divided ratio of the supply voltage before a voltage drop occurs. This preliminary charging state serves as a reference that can be evaluated later to detect whether a voltage drop has happened, even when buffer capacitors are maintaining the supply voltage.
Solution Approach 2:
A control capacitor is introduced as an intermediary element between the supply voltage and the detection system. The control capacitor's voltage, which is divided from the supply voltage, serves as an intermediate signal that reveals the true state of the supply voltage even when the main supply voltage is being buffered by large capacitors.
2Ease of operation
If the operating switch can be locked in the on position, then the power tool can be operated conveniently, but the power tool may be started unintentionally after voltage restoration following a voltage drop
Solution Approach 1:
The control device continuously monitors the charge state of the control capacitor and uses this feedback information to determine whether a voltage drop has occurred. Based on this feedback, the control device can prevent unintentional startup by blocking the start command until the voltage drop condition is resolved, while still allowing normal operation when voltage is stable.
3Device complexity
If the control capacitor is connected directly to the supply voltage for detection, then the detection system is simple, but the high-capacity buffer capacitors with low series resistance prevent accurate detection of voltage drops
Solution Approach 1:
The control capacitor serves as an intermediary measurement element that is charged through a current-limiting resistor from the supply voltage. This intermediary approach allows the detection system to measure a scaled-down version of the supply voltage that is not directly affected by the buffer capacitors' low impedance, thereby enabling precise voltage drop detection.
Solution Approach 2:
The system changes the voltage parameter by using a divided ratio (through the current-limiting resistor and control capacitor combination) of the supply voltage for detection purposes. This parameter transformation allows the detection circuit to operate in a voltage range that is sensitive to drops while being isolated from the high-current buffer capacitor effects.
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 enables reliable detection of voltage drops, enhancing safety by preventing unintentional startup of electric tools and vehicles, and providing effective recovery protection even with buffered supply voltages and multiple battery packs.
Implementation Method 1
a control capacitor whose first electrode is connected to the anode terminal and whose second electrode is connected to the cathode terminal
Implementation Method 2
a measuring device configured to output a discharge signal on a discharge control line as a function of a potential difference detected between the anode terminal and the cathode terminal
Data Source
Figure 1
AI summary
The invention relates to a device (10) for detecting a voltage drop between an anode connection (6) and a cathode connection (7), comprising: a control capacitor (CK), of which the first electrode is connected to the anode connection (6) and the second electrode is connected to the cathode connection (7); a measuring device (13), which is designed to output a discharge signal (y) depending on a potential difference detected between the anode connection (6) and the cathode connection (7) and a first threshold value for the potential difference on a discharge control line (14); a discharge circuit (17) which is connected to the discharge control line (14) and is designed to discharge the control capacitor (CK) depending on the discharge signal (y); and a control device (12), which is designed to detect the voltage drop by evaluating the state of charge of the control capacitor (CK).