Method and device for detecting the closing of a relay magnetic circuit

Abstract

The present application relates to relay and its test field, specifically relates to a kind of detection method and device of relay magnetic circuit closure, series reference coil to relay coil, when relay magnetic circuit is closed, the voltage sharp pulse of downward is generated at the both ends of reference coil, the lowest point of voltage sharp pulse or the position of maximum voltage slope is detected, the accurate time of relay magnetic circuit closure is obtained.Voltage sharp pulse detection method has two kinds:one is using ADC sampling reference coil voltage to send into MCU to judge, another is using differential circuit and threshold judgment circuit, threshold discrimination circuit output signal is sent into MCU to generate interrupt.The present application utilizes the sharp voltage pulse generated by reference coil at the accurate time of relay magnetic circuit closure, accurately detects the accurate time of relay magnetic circuit closure, and can be used for the measurement of relay overstroke and the detection and measurement of secondary pull-in voltage, with better precision and higher efficiency than traditional detection by relay coil current method.

Description

Technical Field

[0001] This invention relates to the field of relay technology, and more specifically to a method and apparatus for detecting the closure of a relay magnetic circuit. Background Technology

[0002] For relay parameter measurement and performance evaluation, determining when the relay's magnetic circuit is closed and measuring the timing of this closure is crucial. Currently, a typical method is the current detection method, which measures and evaluates the relay based on the characteristic that during magnetic circuit closure, the current increases initially upon activation, decreases before closure, and then continues to rise after closure. The current detection method is as follows... Figure 3 As shown, the current value of relay coil 1 is obtained by collecting the voltage value of reference resistor 3 and dividing it by the resistance value of reference resistor 3. The disadvantage of the current detection method is its relatively poor measurement accuracy. This is because the current change during the magnetic circuit closure process is not sharp enough, and the low-point region lasts for a long time, which leads to accuracy issues in time measurement. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a method and apparatus for detecting the closure of a relay magnetic circuit. This voltage-based detection method is applicable to various types of electromagnetic relays. A reference coil 2 or inductor is connected in series with the relay coil 1. At the instant the relay magnetic circuit closes, a downward voltage pulse is generated across the reference coil 2 or inductor, and an upward voltage pulse is generated across the relay coil 1. By detecting the downward voltage pulse across the reference coil 2 or inductor, or the upward voltage pulse across the relay coil 1, the closure of the relay's magnetic circuit can be detected. Compared to current detection methods, the voltage detection method of this invention significantly improves the sharpness of the detected signal during the relay's closure process, thereby greatly improving detection accuracy and the measurement accuracy of the closure moment. It can be used for measuring relay overtravel and determining and measuring the secondary pull-in voltage.

[0004] The present invention is achieved through the following technical solutions.

[0005] This invention relates to a method and apparatus for detecting the closure of a relay magnetic circuit. A reference coil 2 and a relay coil 1 are connected in series. A coil driving circuit 4 applies a driving voltage to both ends of the series-connected relay coil 1 and reference coil 2. The voltage of the reference coil 2 is adjusted to a suitable level by a level adjustment circuit 5. The adjusted voltage signal can be directly sent to an MCU 8 via an ADC. The MCU 8 processes the voltage signal and detects the low point of the downward pulse peak generated when the relay magnetic circuit closes, thus determining whether the relay magnetic circuit is closed and the timing of the closure. The voltage signal adjusted by the level adjustment circuit 5 can also be sent to a differentiating circuit 6 for processing and then sent to a threshold judgment circuit 7. A pulse signal is obtained when the relay magnetic circuit closes. The pulse signal is sent to the MCU 8 to generate an interrupt. The MCU 8 determines whether the relay magnetic circuit is closed and the timing of the closure by judging whether an interrupt is received before or after the relay magnetic circuit closes.

[0006] The principle of the relay magnetic circuit closure detection method and device of the present invention is as follows.

[0007] like Figure 2 As shown, after the relay coil is energized, the driving voltage V remains constant, and the voltage Vr across reference coil 2 is: Vr = i*Rr + dΨ / dt = i*Rr + L*di / dt (1) In the formula, i is the current flowing through relay coil 1 and reference coil 2. Rr is the resistance of reference coil 2. Ψ is the magnetic flux of reference coil 2. L is the inductance of reference coil 2.

[0008] As can be seen from formula (1), in the initial stage of relay activation, the current in relay coil 1 gradually increases, and di / dt>0, relative to... Figure 3 In current current detection methods, the resistance is higher than that of the reference coil 2 in this invention; when the current in relay coil 1 decreases, di / dt < 0, relative to... Figure 3 In the current current detection method, the voltage value of the reference coil 2 is lower; when the current in relay coil 1 changes from decreasing to increasing, di / dt>0, relative to... Figure 3 In current detection methods, the resistance is higher than that of the reference coil 2 in this invention. The voltage change of the reference coil 2 when the relay magnetic circuit is closed in this invention is greater than that obtained through... Figure 3 Current current detection methods, which use changes in resistance voltage to detect changes in current, produce sharper spikes. Attached Figure Description

[0009] Figure 1 : Schematic diagram of the implementation principle of this invention; Figure 2 : Schematic diagram of the voltage detection method of this invention; Figure 3 : Schematic diagram of the current current detection method; Figure 4 : A comparative test principle diagram of the voltage detection method of this invention and the current current detection method; Figure 5 The voltage detection method of this invention and the current current detection method are compared and tested. In the diagram: 1. Relay coil; 2. Reference coil; 3. Reference resistor; 4. Coil drive circuit; 5. Level adjustment circuit; 6. Differentiating circuit; 7. Threshold judgment circuit; 8. MCU. Detailed Implementation

[0010] The following are specific embodiments of the present invention, which further describe the technical solutions of the invention, but the present invention is not limited to these embodiments.

[0011] like Figure 1 As shown, two implementation examples are described.

[0012] In the first implementation example, the reference coil 2 and the relay coil 1 are connected in series. The coil driving circuit 4 applies a driving voltage to both ends of the relay coil 1 and the reference coil 2 connected in series. The voltage of the reference coil 2 is adjusted to a suitable level by the level adjustment circuit 5. The adjusted voltage signal is directly sent to the MCU 8 through the ADC. The MCU 8 processes the voltage signal and detects the low point of the downward pulse peak generated when the relay magnetic circuit is closed, so as to obtain whether the relay magnetic circuit is closed and the time point of closure.

[0013] In the second implementation example, the reference coil 2 and the relay coil 1 are connected in series. The coil driving circuit 4 applies a driving voltage to both ends of the series-connected relay coil 1 and reference coil 2. The voltage of the reference coil 2 is adjusted to a suitable level by the level adjustment circuit 5. The voltage signal adjusted by the level adjustment circuit 5 is sent to the differentiating circuit 6 for processing and then sent to the threshold judgment circuit 7. A pulse signal can be obtained when the relay magnetic circuit is closed. The pulse signal is sent to the MCU 8 to generate an interrupt. The MCU 8 determines whether the relay magnetic circuit is closed and the timing of the closure by judging whether an interrupt is received before or after the relay magnetic circuit is closed.

[0014] Figure 4 This is a comparative test schematic diagram of the present invention and the current current detection method. Reference resistor 3 simulates the current detection method in the current current detection method. The voltage Vr1 across reference resistor 3 has the same variation characteristics as the current in relay coil 1. Reference resistor 3 plus reference coil 2 simulates the reference coil in the present invention, and voltage Vr is the voltage of the simulated reference coil. The test results are as follows... Figure 5 As shown in the figure. In the figure, Vr represents the change of the reference coil voltage during the magnetic circuit closure process, and Vr1 represents the change of the reference resistor 3 voltage during the relay magnetic circuit closure process.

[0015] from Figure 5 The test results show that the relay magnetic circuit closure detection method and device based on the present invention significantly improves the sharpness of the detected signal during the relay closure process, thereby greatly improving the detection accuracy and the measurement accuracy of the closure time.

[0016] The above-disclosed examples are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, but without departing from the spirit of the present invention or exceeding the scope defined by the appended claims.

Claims

1. A method and apparatus for detecting the closure of a relay magnetic circuit, applicable to various types of electromagnetic relays, characterized in that... By connecting a reference coil or inductor in series with the relay coil, a downward voltage pulse is generated across the reference coil or inductor at the instant the relay magnetic circuit closes, and an upward voltage pulse is generated across the relay coil. The closure of the relay magnetic circuit can be detected by detecting the downward voltage pulse across the reference coil or inductor, or by detecting the upward voltage pulse across the relay coil.

2. The relay magnetic circuit closure detection method and apparatus as described in claim 1 uses an ADC to convert the voltage across the reference coil or inductor and sends it to the MCU. The MCU detects whether there is a downward voltage pulse and the position of the pulse based on the characteristics of the voltage across the reference coil, and detects whether the relay magnetic circuit is closed and obtains the closing time.

3. In the relay magnetic circuit closure detection method and apparatus as described in claim 1, the voltage across the reference coil or inductor is fed into the differentiating circuit, the output of the differentiating circuit is sent to the threshold judgment circuit, the signal output of the threshold judgment circuit is sent to the MCU to generate an interrupt, and the MCU detects whether the relay magnetic circuit is closed and obtains the closure time by detecting whether an interrupt is received and the interrupt time.

4. The method and apparatus for detecting the magnetic circuit closure of a relay as described in claim 1, used for measuring the overtravel of an electromagnetic relay.

5. The method and apparatus for detecting the magnetic circuit closure of a relay as described in claim 1, used for detecting and measuring the secondary pull-in voltage of an electromagnetic relay.

6. In the relay magnetic circuit closure detection method and apparatus as described in claim 1, the reference resistor connected in series with the reference coil or inductor is within the scope of this invention.

Images