Frequency converter overcurrent protection detection circuit
By using rectifier diodes in the inverter overcurrent protection detection circuit to rectify the negative peak current to the positive direction, the problems of circuit complexity and cost in the prior art are solved, and the circuit structure is simplified and cost reduction is achieved.
Patent Information
- Application Number
- CN202323463899.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-19
- Publication Date
- 2024-12-31
- Estimated Expiration
- 2033-12-19
AI Technical Summary
The existing inverter overcurrent protection detection circuit needs to compare the peak currents in both positive and negative directions, resulting in complex circuit structure and high cost.
Full-wave rectification is achieved by adding rectifier diodes between the op amp and the comparator, rectifying the negative peak current to the positive current, so that only one comparator can compare the forward current peak, simplifying the circuit structure and reducing costs.
It realizes the simplification of the circuit structure and the reduction of cost, reduces the circuit complexity, and meets the requirements of overcurrent protection detection of the frequency converter.
Smart Images
Figure CN222280771U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of current protection circuits, in particular to an overcurrent protection detection circuit for a frequency converter. Background Art
[0002] A current sensor is placed on the AC side of the inverter to detect the current signal. When using this signal to design the inverter overcurrent protection detection, since it is an AC signal, it is necessary to compare the peak currents in both the positive and negative directions to trigger the fault protection function. Therefore, the usual practice is to set two voltage comparators at the back end of the sampled AC voltage signal, one for comparing the positive phase peak current and the other for comparing the negative current peak current, such as Figure 1 As shown, the above circuit structure is relatively complex and the cost is high. Summary of the invention
[0003] In order to solve the problems of complex circuit structure and high cost in the prior art, the utility model provides an inverter overcurrent protection detection circuit, which can simplify the circuit structure and reduce the cost.
[0004] The technical solution is as follows: an inverter overcurrent protection detection circuit includes an operational amplifier U1A, characterized in that the non-phase input terminal of the operational amplifier U1A is connected to the other end of a resistor R3 whose one end is grounded, the inverting input terminal of the operational amplifier U1A is connected to one end of a resistor R2 and one end of a resistor R4, the other end of the resistor R2 is linked to one end of a resistor R1 and inputs a sampling signal, the other end of the resistor R1 is grounded, the output terminal of the operational amplifier U1A is connected to the positive electrode of a switching diode D1, the negative electrode of the switching diode D1 is connected to an input terminal of a comparator U3A and the other end of the resistor R4, the other input terminal of the comparator U3A is connected to one end of a resistor R5 and one end of a resistor R6, the other end of the resistor R5 is connected to a 5V power supply, the other end of the resistor R6 is grounded, and the output terminal of the comparator U3A is connected to one end of a resistor R7 and one end of a capacitor C5 and is a CPU signal output terminal.
[0005] After adopting the utility model, a rectifier diode D1 is added between the operational amplifier and the comparator, so that the sampling signal can be full-wave rectified and the negative peak value thereof can be rectified to the positive direction. At this time, only one comparator U3A is needed to meet the demand, thus simplifying the circuit and reducing the cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Figure 1 It is a schematic diagram of an existing current protection detection circuit;
[0007] Figure 2 This is a schematic diagram of the protection detection circuit of the utility model. DETAILED DESCRIPTION
[0008] See Figure 2As shown, a frequency converter overcurrent protection detection circuit includes an operational amplifier U1A, a non-phase input terminal of the operational amplifier U1A is connected to the other end of a resistor R3 whose one end is grounded, an inverting input terminal of the operational amplifier U1A is connected to one end of a resistor R2 and one end of a resistor R4, the other end of the resistor R2 is linked to one end of a resistor R1 and inputs a sampling signal, the other end of the resistor R1 is grounded, an output terminal of the operational amplifier U1A is connected to the positive electrode of a rectifier diode D1, a negative electrode of the rectifier diode D1 is connected to an input terminal of a comparator U3A and the other end of the resistor R4, another input terminal of the comparator U3A is connected to one end of a resistor R5 and one end of a resistor R6, the other end of the resistor R5 is connected to a 5V power supply, the other end of the resistor R6 is grounded, and an output terminal of the comparator U3A is connected to one end of a resistor R7 and one end of a capacitor C5 and is a CPU signal output terminal.
[0009] In the present application, the rectifying effect of the rectifier diode D1 is utilized to rectify the negative current peak into a positive current, so one less comparator is required, and only one comparator is needed to compare the forward current peak, which greatly reduces the circuit complexity, simplifies the circuit structure, and reduces the cost.
Claims
1. A frequency converter overcurrent protection detection circuit, comprising an operational amplifier U1A, characterized in that: The non-inverting input terminal of the operational amplifier U1A is connected to the other end of the resistor R3 whose one end is grounded, the inverting input terminal of the operational amplifier U1A is connected to one end of the resistor R2 and one end of the resistor R4, the other end of the resistor R2 is linked to one end of the resistor R1 and inputs the sampling signal, the other end of the resistor R1 is grounded, the output terminal of the operational amplifier U1A is connected to the positive electrode of the switching diode D1, the negative electrode of the switching diode D1 is connected to an input terminal of the comparator U3A and the other end of the resistor R4, the other input terminal of the comparator U3A is connected to one end of the resistor R5 and one end of the resistor R6, the other end of the resistor R5 is connected to a 5V power supply, the other end of the resistor R6 is grounded, and the output terminal of the comparator U3A is connected to one end of the resistor R7 and one end of the capacitor C5 and is the CPU signal output terminal.