Zero-crossing on-off circuit based on MOS tube control

Abstract

The utility model discloses a zero-crossing on-off circuit based on MOS tube control, which comprises a zero-crossing detection circuit used for detecting and tracking the position and time of a positive half-wave and negative half-wave alternating zero-crossing point of alternating current, and comprises an optical coupler E1, the input end of the optical coupler E1 is connected with a rectification filter module, and the output end of the optical coupler E1 is connected with an output filter module; the driving output circuit is used for driving an MOS switch in the driving output circuit to respond in time when the zero-cross detection circuit detects a zero point, the zero-cross detection circuit is connected with the driving output circuit, the MOS switch comprises an MOS tube Q1 and an MOS tube Q2, and a source electrode of the MOS tube Q1 is connected with a source electrode of the MOS tube Q2 in parallel and is used for conducting a positive half cycle and a negative half cycle. According to the utility model, output on-off is carried out at a zero crossing point, and the impact on a load and a power grid is small; by replacing a proper MOS tube, the circuit can be applied to loads with different powers; meanwhile, no mechanical contact exists, the service life is long, and reliability is high.

Description

Technical Field

[0001] The utility model relates to the technical field of zero-crossing on-off circuits, and in particular to a zero-crossing on-off circuit based on MOS tube control. Background Art

[0002] At present, most AC power distribution systems use contactors or circuit breakers to control the on or off of outputs, because this method has the following advantages: contactors can control the on and off of strong currents through weak current signals, which is suitable for occasions that require frequent operations; circuit breakers have automatic circuit breaking functions and can provide overload, short circuit and undervoltage protection; maintenance is simple and the cost is relatively low. However, this method still has the following defects:

[0003] 1. Arcing cannot be avoided: Arcing is easily generated when switching on and off under load, which may cause contact erosion or even melting, affecting the life and reliability of the equipment.

[0004] 2. Impact on the power grid and load: Traditional contactors and circuit breakers may cause current mutations when disconnecting the circuit, thereby causing impact on the power grid and load.

[0005] 3. Unable to achieve precise zero-crossing point control: Since contactors and circuit breakers usually do not have the ability to detect and control the circuit to be turned on and off when the voltage crosses zero, it is impossible to guarantee operation at the most ideal time point, which may increase equipment wear and reduce the overall efficiency of the system.

[0006] It can be seen that how to realize a zero-crossing on-off circuit output in an AC power distribution system is crucial. Utility Model Content

[0007] In order to solve the above technical problems, the utility model provides a zero-crossing on-off circuit based on MOS tube control, comprising:

[0008] A zero-crossing detection circuit is used to detect and track the position and time of the zero-crossing point of the positive half-wave and the negative half-wave of the alternating current, and includes an optical coupler E1, the input end of the optical coupler E1 is connected to a rectifier filter module, and the output end of the optical coupler E1 is connected to an output filter module;

[0009] The drive output circuit is used to drive the MOS switch in the drive output circuit to respond in time when the zero-crossing detection circuit detects the zero point. The zero-crossing detection circuit is connected to the drive output circuit. The MOS switch includes a MOS transistor Q1 and a MOS transistor Q2. The source of the MOS transistor Q1 is connected in parallel with the source of the MOS transistor Q2 for conduction in the positive and negative half cycles.

[0010] Furthermore, the rectification and filtering module includes a capacitor C9, a resistor R15 and a resistor R16; the positive electrode of the input end of the optocoupler E1 is connected to the capacitor C9 and the resistor R15; the negative electrode of the input end of the optocoupler E1 is connected to the resistor R16.

[0011] Furthermore, the output filter module includes capacitor C10, capacitor C11 and resistor R14; the capacitor C10 and capacitor C11 are connected in parallel between the positive and negative poles of the output end of the optocoupler E1, and one end of the resistor R14 is connected to a 3.3V power supply and the other end is connected to the positive pole of the output end of the optocoupler E1.

[0012] Furthermore, the drive output circuit also includes a MOS transistor driver chip N1 and a MOS transistor driver chip N2, the OUT pin of the MOS transistor driver chip N1 is connected to the gate of the MOS transistor Q1; the OUT pin of the MOS transistor driver chip N2 is connected to the gate of the MOS transistor Q2.

[0013] Furthermore, the models of the MOS transistor driver chip N1 and the MOS transistor driver chip N2 are both HSA6880.

[0014] Compared with the prior art, the utility model has the following beneficial effects:

[0015] Compared with the traditional use of contactors or circuit breakers to control the output on or off, the output of the utility model is turned on and off at the zero point, which has little impact on the load and the power grid; by replacing the appropriate MOS tube, it can be used for different power loads; at the same time, there is no mechanical contact, long service life and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A circuit diagram of a zero-crossing detection circuit in the utility model;

[0017] Figure 2 It is a circuit diagram of the driving output circuit in the utility model. DETAILED DESCRIPTION

[0018] In order to make the technical scheme and technical effect of the utility model clearer, the technical scheme in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment. Obviously, the described embodiment is only a part of the embodiment of the utility model, not all of the embodiments.

[0019] The utility model provides a zero-crossing on-off circuit based on MOS tube control, which utilizes the characteristics of semiconductor devices such as diodes and MOS tubes to strictly control the on-off process at the zero-crossing point in the AC power distribution system to avoid impact on the load and the power grid. The on-off principle is as follows:

[0020] When turned on, when the power supply works in the positive half cycle, the negative half cycle MOS tube is turned on. At this time, the circuit is still in the cut-off state and the output has no power. When the voltage passes through zero, the negative half cycle MOS tube is in the on state. Due to the unidirectional conduction characteristics of the MOS tube body diode, the positive half cycle diode is turned on and the output has power. At this time, the positive half cycle MOS tube is turned on and the connection process is completed.

[0021] When shutting down, when the power supply is working in the positive half cycle, the negative half cycle MOS tube is shut down. Due to the unidirectional conduction characteristics of the diode, the body diode of the negative half cycle MOS tube is still turned on and the output is still connected. When crossing zero and entering the second half cycle, the body diode of the negative half cycle MOS tube is reversely cut off. At this time, the output is turned off, and then the positive half cycle MOS tube is turned off, and the shutdown process is completed.

[0022] The utility model mainly comprises a zero-crossing detection circuit and a drive output circuit.

[0023] like Figure 1 As shown, the zero-crossing detection circuit is used to detect and track the position and time of the zero-crossing point of the positive half-wave and negative half-wave of the alternating current. The zero-crossing detection circuit includes an optocoupler E1, the input end of the optocoupler E1 is connected to a rectifier filter module, and the output end of the optocoupler E1 is connected to an output filter module. Among them, the rectifier filter module includes a capacitor C9, a resistor R15 and a resistor R16; the positive pole of the input end of the optocoupler E1 is connected to the capacitor C9 and the resistor R15; the negative pole of the input end of the optocoupler E1 is connected to the resistor R16. The output filter module includes a capacitor C10, a capacitor C11 and a resistor R14; the capacitor C10 and the capacitor C11 are connected in parallel between the positive and negative poles of the output end of the optocoupler E1, and one end of the resistor R14 is connected to a 3.3V power supply, and the other end is connected to the positive pole of the output end of the optocoupler E1.

[0024] When the zero-crossing detection circuit works: The zero-crossing detection circuit is actually a voltage comparator, which rectifies and filters the input signal and then compares it with a reference level. When the input signal passes through the zero point, the output signal will jump, and this jump is the zero-crossing point. Figure 1 When the power supply works in the positive half cycle, the OUT1 voltage is higher than N, the optocoupler E1 is turned on, IN1 is high level, and the microprocessor recognizes it as a positive half cycle; otherwise it is recognized as a negative half cycle.

[0025] like Figure 2As shown, the drive output circuit is used to drive the MOS switch in the drive output circuit to respond in time when the zero-crossing detection circuit detects the zero point. The zero-crossing detection circuit is connected to the drive output circuit. The MOS switch includes a MOS tube Q1 and a MOS tube Q2, and the source of the MOS tube Q1 is connected in parallel with the source of the MOS tube Q2 for positive and negative half-cycle conduction. The drive output circuit also includes a MOS tube driver chip N1 and a MOS tube driver chip N2. The OUT pin of the MOS tube driver chip N1 is connected to the gate of the MOS tube Q1; the OUT pin of the MOS tube driver chip N2 is connected to the gate of the MOS tube Q2. Preferably, the models of the MOS tube driver chip N1 and the MOS tube driver chip N2 are both HSA6880.

[0026] When the drive output circuit is working: when the microprocessor detects that it is in the positive half cycle, it controls the MOS tube driver chip N2 to make its OUT pin output a high level and turn on the MOS tube Q2. At this time, the power supply is working in the positive half cycle. Since the MOS tube Q1 is in the off state and L is higher than OUT1, the output is still off; when the power supply enters the negative half cycle, OUT1 is higher than L, and the MOS tube Q2 is turned on. Due to the presence of the diode in the MOS tube Q1, the loop is turned on and the output is turned on. Then the microprocessor controls the OUT pin of the MOS tube driver chip N1 to output a high level and turn on the MOS tube Q1, and the connection process is completed; the shutdown process is the opposite of the connection process.

[0027] The output of the utility model is turned on and off at the zero point, which has little impact on the load and the power grid; by replacing the appropriate MOS tube, it can be used for different power loads; there is no mechanical contact, long service life, high reliability; at the same time, it has good environmental adaptability and is suitable for places with strong vibration and impact.

[0028] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A zero-crossing on-off circuit based on MOS tube control, characterized in that: include: A zero-crossing detection circuit is used to detect and track the position and time of the zero-crossing point of the positive half-wave and the negative half-wave of the alternating current, and includes an optical coupler E1, the input end of the optical coupler E1 is connected to a rectifier filter module, and the output end of the optical coupler E1 is connected to an output filter module; The drive output circuit is used to drive the MOS switch in the drive output circuit to respond in time when the zero-crossing detection circuit detects the zero point. The zero-crossing detection circuit is connected to the drive output circuit. The MOS switch includes a MOS transistor Q1 and a MOS transistor Q2. The source of the MOS transistor Q1 is connected in parallel with the source of the MOS transistor Q2 for conduction in the positive and negative half cycles.

2. The zero-crossing on-off circuit based on MOS tube control according to claim 1, characterized in that: The rectification and filtering module includes a capacitor C9, a resistor R15 and a resistor R16; the positive electrode of the input end of the optocoupler E1 is connected to the capacitor C9 and the resistor R15; the negative electrode of the input end of the optocoupler E1 is connected to the resistor R16.

3. The zero-crossing on-off circuit based on MOS tube control according to claim 1, characterized in that: The output filter module includes capacitor C10, capacitor C11 and resistor R14; the capacitor C10 and capacitor C11 are connected in parallel between the positive and negative electrodes of the output end of the optocoupler E1, and one end of the resistor R14 is connected to a 3.3V power supply and the other end is connected to the positive electrode of the output end of the optocoupler E1.

4. The zero-crossing on-off circuit based on MOS tube control according to claim 1, characterized in that: The drive output circuit further includes a MOS transistor drive chip N1 and a MOS transistor drive chip N2. The OUT pin of the MOS transistor drive chip N1 is connected to the gate of the MOS transistor Q1; the OUT pin of the MOS transistor drive chip N2 is connected to the gate of the MOS transistor Q2.

5. The zero-crossing on-off circuit based on MOS tube control according to claim 4, characterized in that: The models of the MOS tube driver chip N1 and the MOS tube driver chip N2 are both HSA6880.

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