AC voltage positive and negative half cycle detection circuit
By using an AC voltage detection circuit composed of a current limiting resistor, a first diode and a second diode, the existing detection circuit has been solved with complex structure and high cost, and a low-cost and easy-to-implement positive and negative half-cycle detection of AC voltage is realized, and the detection reliability is improved.
Patent Information
- Application Number
- CN202421820653.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-30
- Publication Date
- 2025-06-17
- Estimated Expiration
- 2034-07-30
AI Technical Summary
The existing AC voltage positive and negative half-cycle detection circuit has complex structure and high cost.
The detection circuit consisting of a current limiting resistor, a first diode and a second diode is used to identify the positive and negative half cycles of the AC voltage through the conduction and clamping voltage of the diode, and the voltage peak detection circuit and the AND gate circuit are used to improve the detection reliability.
It realizes low-cost and easy-to-implement detection of the AC voltage with a positive and negative half cycle, reducing the complexity and cost of the detection circuit, and improving the reliability of the detection.
Smart Images
Figure CN222994559U_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of circuit technologies, and particularly to an AC voltage positive and negative half-cycle detection circuit. Background Art
[0002] In an AC circuit, the voltage is a sine wave that varies with time. The period when the sine wave is greater than zero is the positive half-cycle of the AC voltage, and the period when the sine wave is less than zero is the negative half-cycle of the AC voltage. The positive and negative half-cycles have equal periods, equal frequencies, and equal amplitudes.
[0003] The detection of the positive and negative half-cycles of the AC voltage is applied in various scenarios. For example, in a synchronous PFC control circuit, the synchronous turn-on and turn-off of two synchronous MOSFETs are controlled according to the positive and negative half-cycle polarities of the AC voltage.
[0004] Existing AC voltage positive and negative half-cycle detection circuits have complex structures and high costs, and need to be further improved. Summary of the Utility Model
[0005] Embodiments of the present disclosure provide an AC voltage positive and negative half-cycle detection circuit to solve the problems of complex structure and high cost of existing AC voltage positive and negative half-cycle detection circuits.
[0006] Embodiments of the present disclosure provide an AC voltage positive and negative half-cycle detection circuit, including a current-limiting resistor, a first diode, and a second diode.
[0007] The first end of the current-limiting resistor is used to connect to the first end of the AC voltage, the second end of the current-limiting resistor is connected to the cathode of the first diode, and the cathode of the first diode is used to connect to the second end of the AC voltage.
[0008] The second end of the current-limiting resistor is also connected to the anode of the second diode, and the cathode of the second diode is connected to a first power supply.
[0009] The cathode of the first diode is the output end of the AC voltage positive and negative half-cycle detection circuit.
[0010] In an exemplary embodiment of the present disclosure, the AC voltage positive and negative half-cycle detection circuit further includes a first capacitor, and the first capacitor is connected in parallel across the two ends of the first diode.
[0011] In an exemplary embodiment of the present disclosure, the current-limiting resistor includes a plurality of resistors connected in series.
[0012] In an exemplary embodiment of the present disclosure, the AC voltage positive and negative half-cycle detection circuit further includes a voltage peak detection circuit and an AND gate circuit.
[0013] The voltage peak detection circuit is configured to detect an abnormal state of an AC voltage peak. The output terminal of the voltage peak detection circuit is connected to the first input terminal of the AND gate circuit. The cathode of the first diode is connected to the second input terminal of the AND gate circuit. The output terminal of the AND gate circuit is the output terminal of the AC voltage positive and negative half-cycle detection circuit.
[0014] In an exemplary embodiment of the present disclosure, the peak detection circuit includes a voltage acquisition circuit, a third diode, a second capacitor, a resistor R12, and a comparison circuit connected in sequence.
[0015] The voltage acquisition circuit is configured to acquire an AC voltage. The output terminal of the voltage acquisition circuit is connected to the anode of the third diode. The cathode of the third diode is connected to the first end of the second capacitor. The second end of the second capacitor is grounded. The resistor R12 is connected in parallel across the two ends of the second capacitor.
[0016] The first end of the second capacitor is connected to the input terminal of the comparison circuit. The comparison circuit is configured to compare the first end of the second capacitor with a reference voltage to output an abnormal state of the AC voltage peak.
[0017] In an exemplary embodiment of the present disclosure, the comparison circuit includes a first comparator, a second comparator, a fourth diode, a fifth diode, and a NOT gate circuit. The reference voltage includes a first reference voltage and a second reference voltage.
[0018] The first end of the second capacitor is connected to the non-inverting input terminal of the first comparator. The first reference voltage is connected to the inverting input terminal of the first comparator. The output terminal of the first comparator is connected to the anode of the fourth diode. The cathode of the fourth diode is connected to the input terminal of the NOT gate circuit. The output terminal of the NOT gate circuit is the output terminal of the comparison circuit.
[0019] The first end of the second capacitor is connected to the inverting input terminal of the second comparator. The second reference voltage is connected to the non-inverting input terminal of the second comparator. The output terminal of the second comparator is connected to the anode of the fifth diode. The cathode of the fifth diode is connected to the cathode of the fourth diode.
[0020] In an exemplary embodiment of the present disclosure, the voltage acquisition circuit includes resistors R5, R6, R7, R11, R8, R9, R10 connected in series, and an operational amplifier U1A.
[0021] The first end of the resistor R11 is connected to the non-inverting input terminal of the operational amplifier U1A. The second end of the resistor R11 is connected to the inverting input terminal of the operational amplifier U1A. The output terminal of the operational amplifier U1A is the output terminal of the voltage acquisition circuit.
[0022] The AC voltage positive and negative half-cycle detection circuit provided by the embodiments of the present disclosure has the following working principle and beneficial effects:
[0023] In the positive half-cycle of the AC voltage in the embodiments of the present disclosure, the anode voltage of the second diode is greater than the cathode voltage, and the second diode conducts. The first terminal of the AC voltage, the current-limiting resistor, the second diode, the internal resistance of the first power supply, and the second terminal of the AC voltage form a first detection loop. The cathode of the second diode is connected to the first power supply, and the anode voltage of the second diode is clamped to the voltage of the first power supply. The anode voltage of the second diode is recognized as a high-level signal by the external controller. That is, when the external controller receives the high-level signal output by the AC voltage positive and negative half-cycle detection circuit, it is determined that it is the positive half-cycle of the AC voltage.
[0024] Similarly, in the negative half-cycle of the AC voltage, the anode voltage of the first diode is greater than the cathode voltage, and the first diode conducts. The second terminal of the AC voltage, the first diode, the current-limiting resistor, and the first terminal of the AC voltage form a second detection loop. The cathode of the first diode is connected to the second terminal of the AC voltage, and the anode voltage of the first diode is clamped to 0V. The anode voltage of the second diode is recognized as a low-level signal by the external controller. That is, when the external controller receives the low-level signal output by the AC voltage positive and negative half-cycle detection circuit, it is determined that it is the negative half-cycle of the AC voltage.
[0025] In the embodiments of the present disclosure, the positive and negative half-cycles of the AC voltage can be detected by using resistors and diodes. Compared with the traditional method of using a zero-crossing comparator to detect the positive and negative half-cycles of the AC voltage, the detection circuit of this embodiment has a lower cost and is easier to implement. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.
[0027] Figure 1 is the schematic diagram of the AC voltage positive and negative half-cycle detection circuit provided by the embodiments of the present disclosure;
[0028] Figure 2 is the schematic diagram of the AC voltage positive half-cycle detection circuit provided by the embodiments of the present disclosure;
[0029] Figure 3 is the schematic diagram of the AND gate circuit provided by the embodiments of the present disclosure;
[0030] Figure 4 is the schematic diagram of the voltage peak detection circuit provided by the embodiments of the present disclosure. Detailed implementation mode
[0031] In order to enable those skilled in the art to better understand this solution, the following will clearly describe the technical solutions in the embodiments of this solution in conjunction with the accompanying drawings in the embodiments of this solution. Obviously, the described embodiments are some of the embodiments of this solution, rather than all of the embodiments. Based on the embodiments in this solution, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this solution.
[0032] The terms "including" and any other variations in the specification, claims, and the above-mentioned accompanying drawings of this solution mean "including but not limited to", intending to cover non-exclusive inclusion, and not limited to the examples listed in the text. In addition, terms such as "first" and "second" are used to distinguish different objects, rather than to describe a specific order.
[0033] The following will describe in detail the implementation of this disclosure in conjunction with specific accompanying drawings:
[0034] Referring to Figure 1 - Figure 2 , the positive and negative half-cycle detection circuit of the AC voltage includes a current-limiting resistor, a first diode, and a second diode.
[0035] The first end of the current-limiting resistor is used to connect to the first end of the AC voltage, the second end of the current-limiting resistor is connected to the cathode of the first diode, and the cathode of the first diode is used to connect to the second end of the AC voltage.
[0036] The second end of the current-limiting resistor is also connected to the anode of the second diode, and the cathode of the second diode is connected to the first power supply.
[0037] The cathode of the first diode is the output end of the positive and negative half-cycle detection circuit of the AC voltage.
[0038] Referring to Figure 1 - Figure 2 , in this embodiment, during the positive half-cycle of the AC voltage, the anode voltage of the second diode D2 is greater than the cathode voltage, and the second diode D2 conducts. The first end ACL of the AC voltage, the current-limiting resistor, the second diode D2, the internal resistance of the first power supply, and the second end ACN of the AC voltage form a first detection loop. The cathode of the second diode D2 is connected to the first power supply, and the anode voltage of the second diode D2 is clamped to the voltage of the first power supply. The anode voltage of the second diode D2 is recognized as a high-level signal by the external controller. That is, when the external controller receives the high-level signal output by the positive and negative half-cycle detection circuit of the AC voltage, it is determined that it is the positive half-cycle of the AC voltage.
[0039] Similarly, referring to Figure 1, during the negative half-cycle of the AC voltage, the anode voltage of the first diode D1 is greater than the cathode voltage, and the first diode D1 conducts. The second terminal ACN of the AC voltage, the first diode D1, the current-limiting resistor, and the first terminal ACL of the AC voltage form a second detection circuit. The cathode of the first diode D1 is connected to the second terminal ACN of the AC voltage, the anode voltage of the first diode D1 is clamped to 0V, and the anode voltage of the second diode D2 is recognized by the external controller as a low-level signal. That is, when the external controller receives the low-level signal output by the positive and negative half-cycle detection circuit of the AC voltage, it determines that it is the negative half-cycle of the AC voltage.
[0040] In the embodiments of the present disclosure, resistors and diodes can be used to implement the detection of the positive and negative half-cycles of the AC voltage. Compared with the traditional method of using a zero-crossing comparator to detect the positive and negative half-cycles of the AC voltage, the detection circuit of this embodiment has a lower cost and is easier to implement.
[0041] Refer to Figure 1 , in an exemplary embodiment of the present disclosure, the positive and negative half-cycle detection circuit of the AC voltage further includes a first capacitor, and the first capacitor is connected in parallel across the two ends of the first diode.
[0042] In this embodiment, the first capacitor plays a filtering role, which is used to filter out the interference signals caused by the AC signal and other circuits, and avoid the detection error of the positive and negative half-cycles of the AC voltage caused by the interference signals.
[0043] In an exemplary embodiment of the present disclosure, the current-limiting resistor includes a plurality of resistors connected in series.
[0044] In this embodiment, the current-limiting resistor adopts the form of resistors R1, R2, R3, and R4 connected in series. By adjusting the number and resistance value of the series resistors, the current of the first detection circuit and the second detection circuit can be adjusted, thereby improving the versatility of this embodiment.
[0045] Refer to Figure 3 - Figure 4 , in an exemplary embodiment of the present disclosure, the positive and negative half-cycle detection circuit of the AC voltage further includes a voltage peak detection circuit and an AND gate circuit,
[0046] The voltage peak detection circuit is configured to detect the abnormal state of the AC voltage peak. The output terminal of the voltage peak detection circuit is connected to the first input terminal of the AND gate circuit, the cathode of the first diode is connected to the second input terminal of the AND gate circuit, and the output terminal of the AND gate circuit is the output terminal of the positive and negative half-cycle detection circuit of the AC voltage.
[0047] In this embodiment, when the AC voltage is normal, the voltage peak detection circuit outputs a normal state (e.g., high level), and this high-level signal is connected to the first input terminal of the AND gate circuit U3. The level signal at the output terminal of the AND gate circuit U3 is the same as the level signal at the cathode of the first diode D1. That is, when the AC voltage is normal, the settings of the voltage peak detection circuit and the AND gate circuit do not affect the detection results of the positive and negative half-cycles of the AC voltage.
[0048] When the AC voltage is abnormal, the voltage peak detection circuit outputs an abnormal state (e.g., low level), and this low-level signal is connected to the first input terminal of the AND gate circuit U3. Regardless of whether the cathode of the first diode D1 is at a high level or a low level, a low-level signal will be output at the output terminal of the AND gate circuit U3. When the external controller receives a continuous low-level signal, it determines that the AC voltage is abnormal.
[0049] In this embodiment, the settings of the voltage peak detection circuit and the AND gate circuit U3 can realize the identification of the abnormal state of the AC voltage, improving the reliability of the detection of the positive and negative half-cycles of the AC voltage.
[0050] Refer to Figure 4 , in an exemplary embodiment of the present disclosure, the peak detection circuit includes a voltage acquisition circuit, a third diode, a second capacitor, a resistor R12, and a comparison circuit connected in sequence.
[0051] The voltage acquisition circuit is configured to acquire the AC voltage. The output terminal of the voltage acquisition circuit is connected to the anode of the third diode. The cathode of the third diode is connected to the first end of the second capacitor. The second end of the second capacitor is grounded. The resistor R12 is connected in parallel across the two ends of the second capacitor.
[0052] The first end of the second capacitor is connected to the input terminal of the comparison circuit. The comparison circuit is configured to compare the first end of the second capacitor with a reference voltage to output an abnormal state of the peak value of the AC voltage.
[0053] In this embodiment, the voltage acquisition circuit is used to acquire the AC voltage and output a voltage signal proportional to the AC voltage. In the positive half-cycle of the AC voltage, the third diode D3 conducts, and the output voltage of the voltage acquisition circuit charges the second capacitor C2. The voltage of the second capacitor C2 increases. When the voltage of the second capacitor C2 reaches the peak voltage of the AC voltage, the second capacitor C2 stops charging. In the negative half-cycle of the AC voltage, the third diode D3 is cut off, and the second capacitor C2 discharges through the resistor R12 to prepare for the next charging. Through the above process, the terminal voltage of the second capacitor C2 is the peak voltage of the AC voltage.
[0054] Refer to Figure 4, in an exemplary embodiment of the present disclosure, the comparison circuit includes a first comparator, a second comparator, a fourth diode, a fifth diode, and a NOT gate circuit, and the reference voltage includes a first reference voltage and a second reference voltage.
[0055] The first end of the second capacitor is connected to the non-inverting input terminal of the first comparator, the first reference voltage is connected to the inverting input terminal of the first comparator, the output terminal of the first comparator is connected to the anode of the fourth diode, the cathode of the fourth diode is connected to the input terminal of the NOT gate circuit, and the output terminal of the NOT gate circuit is the output terminal of the comparison circuit.
[0056] The first end of the second capacitor is connected to the inverting input terminal of the second comparator, the second reference voltage is connected to the non-inverting input terminal of the second comparator, the output terminal of the second comparator is connected to the anode of the fifth diode, and the cathode of the fifth diode is connected to the cathode of the fourth diode.
[0057] In this embodiment, when the AC voltage is within the normal range, the voltage at the first end of the second capacitor C2 is less than the first reference voltage REF1, the first comparator U2A outputs a low-level signal. At the same time, the voltage at the first end of the second capacitor C2 is greater than the second reference voltage REF2, the second comparator U2B outputs a low-level signal, and the output terminal of the NOT gate circuit U4 is a high-level signal.
[0058] When the AC voltage is too high, the voltage at the first end of the second capacitor C2 is greater than the first reference voltage REF1, the first comparator U2A outputs a high-level signal, which causes the cathode of the fourth diode D4 to be at a high level, and the output terminal of the NOT gate U4 is at a low level; or when the AC voltage is too low, the voltage at the first end of the second capacitor C2 is less than the second reference voltage REF2, the second comparator U2B outputs a high-level signal, which causes the cathode of the fourth diode D4 to be at a high level, and the output terminal of the NOT gate U4 is at a low level. Through the above analysis process, it can be seen that when the AC voltage exceeds the normal range, it will cause the output terminal of the NOT gate U4 to be at a low-level signal.
[0059] In this embodiment, the setting of the first comparator, the second comparator, the fourth diode, the fifth diode, and the NOT gate circuit realizes the hardware detection of the abnormal state of the AC voltage, which is beneficial to improving the response speed of the abnormal state of the AC voltage.
[0060] Referring to Figure 4 , in an exemplary embodiment of the present disclosure, the voltage acquisition circuit includes resistors R5, R6, R7, R11, R8, R9, R10 connected in series, and an operational amplifier U1A.
[0061] The first end of the resistor R11 is connected to the non-inverting input terminal of the operational amplifier U1A, the second end of the resistor R11 is connected to the inverting input terminal of the operational amplifier U1A, and the output terminal of the operational amplifier U1A is the output terminal of the voltage acquisition circuit.
[0062] In this embodiment, resistors R5, R6, R7, R11, R8, R9, and R10 form a resistor voltage division circuit, and the AC voltage can be obtained by detecting the terminal voltage of resistor R11. Resistors R13 and R15 and operational amplifier U1A form a subtraction circuit for detecting the terminal voltage of resistor R11. The circuit structure is simple and easy to implement.
[0063] The above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them; although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the present disclosure.
Claims
1. An AC voltage positive and negative half-cycle detection circuit, characterized in that: comprising a current limiting resistor, a first diode and a second diode, The first end of the current limiting resistor is used to be connected to the first end of the AC voltage, the second end of the current limiting resistor is connected to the cathode of the first diode, and the cathode of the first diode is used to be connected to the second end of the AC voltage. The second end of the current limiting resistor is also connected to the anode of the second diode, and the cathode of the second diode is connected to the first power supply. The cathode of the first diode is the output end of the AC voltage positive and negative half-cycle detection circuit.
2. The AC voltage positive and negative half-cycle detection circuit according to claim 1, characterized in that: The device also includes a first capacitor, which is connected in parallel at both ends of the first diode.
3. The AC voltage positive and negative half-cycle detection circuit according to claim 1, characterized in that: The current limiting resistor includes a plurality of resistors connected in series.
4. The AC voltage positive and negative half-cycle detection circuit according to claim 1, characterized in that: It also includes a voltage peak detection circuit and an AND gate circuit. The voltage peak detection circuit is configured to detect the abnormal state of the AC voltage peak, the output end of the voltage peak detection circuit is connected to the first input end of the AND gate circuit, the cathode of the first diode is connected to the second input end of the AND gate circuit, and the output end of the AND gate circuit is the output end of the AC voltage positive and negative half-cycle detection circuit.
5. The AC voltage positive and negative half-cycle detection circuit according to claim 4, characterized in that: The peak detection circuit includes a voltage acquisition circuit, a third diode, a second capacitor, a resistor R12 and a comparison circuit connected in sequence. The voltage acquisition circuit is configured to acquire an AC voltage, the output end of the voltage acquisition circuit is connected to the anode of the third diode, the cathode of the third diode is connected to the first end of the second capacitor, the second end of the second capacitor is grounded, and the resistor R12 is connected in parallel to both ends of the second capacitor. The first end of the second capacitor is connected to the input end of the comparison circuit, and the comparison circuit is configured to compare the first end of the second capacitor with a reference voltage to output an abnormal state of an AC voltage peak.
6. The AC voltage positive and negative half-cycle detection circuit according to claim 5, characterized in that: The comparison circuit includes a first comparator, a second comparator, a fourth diode, a fifth diode and a NOT gate circuit, and the reference voltage includes a first reference voltage and a second reference voltage. The first end of the second capacitor is connected to the non-inverting input end of the first comparator, the first reference voltage is connected to the inverting input end of the first comparator, the output end of the first comparator is connected to the anode of the fourth diode, the cathode of the fourth diode is connected to the input end of the NOT gate circuit, and the output end of the NOT gate circuit is the output end of the comparison circuit. The first end of the second capacitor is connected to the inverting input of the second comparator, the second reference voltage is connected to the non-inverting input of the second comparator, the output of the second comparator is connected to the anode of the fifth diode, and the cathode of the fifth diode is connected to the cathode of the fourth diode.
7. The AC voltage positive and negative half-cycle detection circuit according to claim 5, characterized in that: The voltage acquisition circuit includes a resistor R5, a resistor R6, a resistor R7, a resistor R11, a resistor R8, a resistor R9, a resistor R10, and an operational amplifier U1A connected in series. The first end of the resistor R11 is connected to the non-inverting input end of the operational amplifier U1A, the second end of the resistor R11 is connected to the inverting input end of the operational amplifier U1A, and the output end of the operational amplifier U1A is the output end of the voltage acquisition circuit.