Zero-Crossing Detection Circuit for Diode Conduction Load Voltage Sensing
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Solution Overview
Problem
Current LED driving circuits are complex, voluminous, and costly due to their reliance on transformers for load detection, making them inefficient for detecting current zero-crossing points and load voltage.
Innovation Solution
A circuit and method utilizing a load power supply circuit with a diode and inductor in series, combined with a voltage-dividing resistor and zero-crossing detection circuit, which includes a sampling and maintaining module and comparator to determine current zero-crossing points and calculate load voltage efficiently, reducing circuit complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transformer is used for load detection in LED driving circuits, then the detection function is achieved, but the circuit becomes complex, voluminous, and costly
Solution Approach 1:
The patent extracts the load detection function from the transformer and implements it separately using a voltage-dividing resistor connected to the transistor switch. This separates the detection function from the power transformation function, eliminating the need for a transformer while maintaining reliable load detection capability.
Solution Approach 2:
The patent introduces a voltage-dividing resistor as an intermediary element to detect load conditions. Instead of using a transformer to detect load, the voltage-dividing resistor provides a simplified intermediary path to obtain voltage information proportional to the load state, reducing circuit complexity.
2Reliability
If a transformer is used for load detection, then the detection capability is provided, but the circuit volume increases
Solution Approach 1:
The detection capability is extracted from the transformer and implemented using compact electronic components (voltage-dividing resistor, transistor, comparator). This removes the bulky transformer while preserving the essential detection function, significantly reducing circuit volume.
Solution Approach 2:
The patent creates a simplified electrical model of the load detection function using passive components and active devices that replicate the transformer's detection capability without its physical bulk. The voltage-dividing network copies the essential detection behavior in a compact form.
3Reliability
If a transformer is used for load detection, then the detection function is achieved, but the cost increases
Solution Approach 1:
The detection function is extracted from the expensive transformer and implemented using low-cost discrete components. The voltage-dividing resistor, transistor switch, and comparator are significantly cheaper than a transformer, reducing manufacturing cost while maintaining detection reliability.
Solution Approach 2:
The patent replaces the expensive, durable transformer with inexpensive electronic components that achieve the same detection function. The voltage-dividing resistor and transistor combination provides a cost-effective alternative that maintains adequate detection reliability for LED driving applications.
4Device complexity
If conventional circuits are used, then the circuit structure is established, but the detection speed of current zero-crossing point and load voltage is slow
Solution Approach 1:
The patent replaces conventional slow detection methods with a fast electronic detection circuit using a comparator. The comparator rapidly compares the voltage signal from the voltage-dividing resistor against a reference, enabling high-speed detection of current zero-crossing points and load voltage changes.
Solution Approach 2:
The patent changes the detection parameter from direct current measurement to voltage measurement through a voltage-dividing network. This parameter transformation enables faster detection because voltage signals can be processed more rapidly by electronic comparators than current signals processed by conventional methods.
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 rapid detection of current zero-crossing points and load voltage with high efficiency and low cost, simplifying the circuit structure while maintaining high detection accuracy.
Implementation Method 1
a voltage-dividing resistor, the voltage-dividing terminal of the voltage-dividing resistor is connected to the signal input terminal of the zero-crossing detection circuit
Implementation Method 2
the load voltage is controlled by the transistor switch
Implementation Method 3
a second comparator, one end of the second reference voltage module is connected to the first input terminal of the second comparator, and the signal input terminal is used as the second input terminal of the second comparator
Data Source
AI summary
A circuit and a method for detecting a current zero-crossing point, and a circuit and method for detecting a load voltage are disclosed. The circuit for detecting current zero-crossing point includes: a load power supply circuit (14), a voltage-dividing resistor (16), a transistor switch (15), a zero-crossing detection circuit (19); the load power supply circuit (14) includes: a load (11), a diode (13), and an inductor (12); one end of the load power supply circuit (14) is connected with the operating voltage input terminal, the other end of the load power supply circuit (14) is connected with a first end of the transistor switch (15) and a first end of the voltage-dividing resistor (16), a second end of the voltage-dividing resistor (16) and a second end of the transistor switch (15) are connected with the ground, the load voltage is controlled by the transistor switch (15), the voltage-dividing terminal of the voltage-dividing resistor (16) is connected to a signal input terminal of the zero-crossing detection circuit (19), the zero-crossing detection circuit (19) is used to determine whether the current of the diode (13) crosses zero to obtain the on time of the diode (13), and the circuit for detecting load voltage uses the on time of the diode (13) and the on time of the transistor switch (15) to obtain the load voltage. The circuits are simple, but with high detection efficiency and low cost.