Switching power supply

Abstract

The utility model relates to the technical field of switching power supplies, and discloses a switching power supply, which comprises a transformer, a rectifier bridge based on an MOS (Metal Oxide Semiconductor) tube, a filtering unit, a voltage stabilizing unit, a zero point detection unit and a control unit, in actual use, the rectifier bridge is set to be of an MOS tube structure, and the zero point of the alternating current is detected through the zero point detection unit, so that rectification can be realized by controlling the on-off of the MOS tube through the zero point of the alternating current, and the rectification is realized by controlling the on-off of the MOS tube without voltage drop when the diode is used for rectification; the power consumption of the switching power supply in actual use can be reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of switching power supplies, in particular to a switching power supply. Background Art

[0002] In the field of industrial automation, switching power supplies are often used to convert 220V AC into 24V DC, and 24V DC is used to provide power for related devices such as PLCs, touch screens, servo motor drivers, and sensors.

[0003] For a switching power supply, since it needs to convert AC power into DC power, a rectifier bridge is provided in the switching power supply to rectify the input AC power. For the rectifier bridge structure in the existing switching power supply, most of them are diode structures. For example, the flyback switching power supply disclosed in the patent document with publication number CN114900046A uses diodes to form a rectifier structure.

[0004] For the rectifier bridge composed of diodes, although it takes advantage of the unidirectional conduction characteristics of the diodes for rectification and does not require the participation of peripheral control devices, the conduction voltage drop of the diodes themselves will generate additional power consumption during rectification. Utility Model Content

[0005] In view of the shortcomings of the background technology, the utility model provides a switching power supply, and the technical problem to be solved is that the existing switching power supply has the problem of large additional power consumption because it adopts a diode-based rectifier bridge for rectification.

[0006] In order to solve the above technical problems, the utility model provides the following technical solutions: a switching power supply, including a transformer, a rectifier bridge based on a MOS tube, a filtering unit, a voltage stabilizing unit, a zero point detection unit and a control unit;

[0007] The rectifier bridge includes a MOS tube M1, a MOS tube M2, a MOS tube M3 and a MOS tube M4; the drain of the MOS tube M1 is electrically connected to the drain of the MOS tube M3, which is a first DC connection terminal DC0 of the rectifier bridge; the source of the MOS tube M1 is electrically connected to the drain of the MOS tube M2, which is a first AC connection terminal AC10 of the rectifier bridge; the source of the MOS tube M3 is electrically connected to the drain of the MOS tube M4, which is a second AC connection terminal AC11 of the rectifier bridge; the source of the MOS tube M2 is electrically connected to the source of the MOS tube M4, which is a second DC connection terminal DC1 of the rectifier bridge;

[0008] The transformer is used to convert the input 22V AC power into 24V AC power, the first AC output terminal and the second AC output terminal of the transformer are electrically connected to the first AC connection terminal AC10 and the second AC connection terminal AC11 of the rectifier bridge respectively, and the first DC connection terminal DC0 and the second DC connection terminal DC1 of the rectifier bridge are electrically connected to the filter unit and the voltage stabilizing unit respectively;

[0009] The zero point detection unit is electrically connected to the first AC output terminal and the second AC output terminal of the transformer, and is used to detect the zero point signal of the AC power output by the transformer, and input the detection signal to the control unit. Based on the detection signal, the control unit sends control signals for controlling the on and off of the MOS tubes M1, M2, M3 and M4 to the gates of the MOS tubes M1, M2, M3 and M4 respectively.

[0010] In some implementations, the filtering unit includes a filtering capacitor, the first DC connection terminal DC0 is electrically connected to one end of the filtering capacitor, and the second DC connection terminal DC1 is electrically connected to the other end of the filtering capacitor.

[0011] In a certain embodiment, the voltage stabilizing unit includes a voltage stabilizing chip of model LM7824, a capacitor C1 and a capacitor C2, the input end of the voltage stabilizing chip is electrically connected to the first DC connection terminal DC0 and one end of the capacitor C1 respectively, the output end of the voltage stabilizing chip is electrically connected to one end of the capacitor C2, and the ground end of the voltage stabilizing chip, the other end of the capacitor C1 and the other end of the capacitor C2 are all electrically connected to the second DC connection terminal DC1.

[0012] In a certain embodiment, the zero point detection unit includes a transistor Q11, a transistor Q12, a transistor Q13, a Zener diode Z11, a Zener diode Z12, a resistor R10, a resistor R11 and a resistor R12, the emitter of the transistor Q11, the emitter of the transistor Q12 and the base of the transistor Q13 are respectively electrically connected to the first AC output end of the transformer, and the base of the transistor Q11 is respectively connected to the base of the transistor Q12, the collector of the transistor Q12, and the base of the Zener diode Z12. The cathode of the transistor Q13 is electrically connected, the emitter of the transistor Q13 is electrically connected to the anode of the Zener diode Z11, the cathode of the Zener diode Z11 is electrically connected to the anode of the Zener diode Z12 and one end of the resistor R10 respectively, the other end of the resistor R10 is electrically connected to the second AC output end of the transformer, the collector of the transistor Q11 and the collector of the transistor Q3 are both electrically connected to one end of the resistor R11, the other end of the resistor R11 is grounded through the resistor R12, and is electrically connected to the control unit, and sends a detection signal to the control unit.

[0013] In some implementations, the other end of the resistor R11 sends a detection signal to the control unit via an optocoupler isolation unit.

[0014] In a certain embodiment, the optocoupler isolation unit includes a photocoupler U1, a resistor R20, a resistor R21, a resistor R22 and a voltage conversion unit, the other end of the resistor R11 is electrically connected to pin 1 of the photocoupler U1, pin 2 of the photocoupler U1 is grounded through the resistor R20, the voltage conversion unit is electrically connected to the first DC output terminal DC0, and is used to convert the voltage at the first DC output terminal DC0 into a 5V voltage input to pin 4 of the photocoupler U1, and pin 3 of the photocoupler is electrically connected to the control unit through the resistor R21 and is grounded through the resistor R22.

[0015] In some implementations, the control unit is a single chip microcomputer.

[0016] Compared with the prior art, the utility model has the following beneficial effects: the utility model sets the rectifier bridge as a MOS tube structure, and detects the zero point of the alternating current through a zero point detection unit, so that rectification can be achieved by controlling the on-off of the MOS tube through the zero point of the alternating current, and rectification is achieved by controlling the on-off of the MOS tube without the voltage drop when the diode is used for rectification, which can reduce the power consumption of the switching power supply when it is actually used. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the utility model in the embodiment;

[0018] Figure 2 is a circuit diagram of a rectifier bridge in an embodiment;

[0019] Figure 3 is a circuit diagram of a zero point detection unit in an embodiment;

[0020] Figure 4 is a circuit diagram of an optical coupling isolation unit in an embodiment;

[0021] Figure 5 is a circuit diagram of a voltage stabilizing unit in an embodiment. DETAILED DESCRIPTION

[0022] Now the utility model is further described in detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the utility model in a schematic manner, and therefore only show the components related to the utility model.

[0023] like Figure 1 As shown, a switching power supply includes a transformer 1, a rectifier bridge 2 based on a MOS tube, a filter unit 3, a voltage stabilizing unit 4, a zero point detection unit 5 and a control unit 6;

[0024] Reference Figure 2 The rectifier bridge 2 includes a MOS tube M1, a MOS tube M2, a MOS tube M3 and a MOS tube M4; the drain of the MOS tube M1 is electrically connected to the drain of the MOS tube M3, which is the first DC connection terminal DC0 of the rectifier bridge 2; the source of the MOS tube M1 is electrically connected to the drain of the MOS tube M2, which is the first AC connection terminal AC10 of the rectifier bridge 2; the source of the MOS tube M3 is electrically connected to the drain of the MOS tube M4, which is the second AC connection terminal AC11 of the rectifier bridge 2; the source of the MOS tube M2 is electrically connected to the source of the MOS tube M4, which is the second DC connection terminal DC1 of the rectifier bridge;

[0025] The transformer 1 is used to convert the input 22V AC power into 24V AC power. The first AC output terminal AC0 and the second AC output terminal AC1 of the transformer 1 are electrically connected to the first AC connection terminal AC10 and the second AC connection terminal AC11 of the rectifier bridge 2 respectively. The first DC connection terminal DC0 and the second DC connection terminal DC1 of the rectifier bridge 2 are electrically connected to the filter unit 3 and the voltage stabilizing unit 4 respectively. The first DC connection terminal DC0 of the rectifier bridge 2 is used to output the rectified DC voltage. The filter unit 3 is used to stabilize the DC voltage and eliminate the harmonic voltage in the DC voltage. The voltage stabilizing unit 4 is used to stabilize the DC voltage and output a stable 24V DC voltage.

[0026] The zero point detection unit 5 is electrically connected to the first AC output terminal AC0 and the second AC output terminal AC1 of the transformer 1, and is used to detect the zero point signal of the AC power output by the transformer 1, and input the detection signal to the control unit 6. The control unit 6 sends control signals for controlling the on and off of the MOS tubes M1, M2, M3 and M4 to the gates of the MOS tubes M1, M2, M3 and M4 respectively based on the detection signal; wherein the control signals include control signals Co1, Co2, Co3 and Co4; when the control signals Co1, Co2, Co3 and Co4 are at a high level, the corresponding MOS tubes are turned on; when the control signals Co1, Co2, Co3 and Co4 are at a low level, the corresponding MOS tubes are turned off; it should be noted that in this embodiment, the MOS tubes M1 and M4 are turned on at the same time, the MOS tubes M2 and M3 are turned on at the same time, and the MOS tubes M1 and M3 are not turned on at the same time.

[0027] In actual use, the utility model sets the rectifier bridge 2 as a MOS tube structure, and detects the zero point of the alternating current through the zero point detection unit 5, so that rectification can be achieved by controlling the on-off of the MOS tube through the zero point of the alternating current. By controlling the on-off of the MOS tube to achieve rectification without the voltage drop when the diode is used for rectification, the power consumption of the switching power supply in actual use can be reduced.

[0028] Specifically, in this embodiment, the filter unit 3 includes a filter capacitor, the first DC connection terminal DC0 is electrically connected to one end of the filter capacitor, and the second DC connection terminal DC1 is electrically connected to the other end of the filter capacitor.

[0029] Specifically, in this embodiment, Figure 5 As shown, the voltage stabilizing unit 4 includes a voltage stabilizing chip U2 of model LM7824, a capacitor C1 and a capacitor C2, the input end of the voltage stabilizing chip U2 is electrically connected to the first DC connection end DC0 and one end of the capacitor C1 respectively, the output end V0 of the voltage stabilizing chip U2 is electrically connected to one end of the capacitor C2, the ground end of the voltage stabilizing chip U2, the other end of the capacitor C1 and the other end of the capacitor C2 are all electrically connected to the second DC connection end DC1 for grounding.

[0030] Specifically, in this embodiment, Figure 3 As shown, the zero point detection unit 5 includes a transistor Q11, a transistor Q12, a transistor Q13, a voltage regulator diode Z11, a voltage regulator diode Z12, a resistor R10, a resistor R11 and a resistor R12, the emitter of the transistor Q11, the emitter of the transistor Q12 and the base of the transistor Q13 are respectively electrically connected to the first AC output terminal AC0 of the transformer 1, the base of the transistor Q11 is respectively electrically connected to the base of the transistor Q12, the collector of the transistor Q12 and the negative electrode of the voltage regulator diode Z12, the emitter of the transistor Q13 ... It is electrically connected to the positive electrode of the Zener diode Z11, the negative electrode of the Zener diode Z11 is electrically connected to the positive electrode of the Zener diode Z12 and one end of the resistor R10 respectively, the other end of the resistor R10 is electrically connected to the second AC output terminal AC1 of the transformer 1, the collector of the transistor Q11 and the collector of the transistor Q13 are both electrically connected to one end of the resistor R11, the other end of the resistor R11 is grounded through the resistor R12, and is electrically connected to the control unit 6 to send a detection signal to the control unit 6; wherein the resistor R11 and the resistor R12 form a resistor voltage divider circuit.

[0031] In actual use, the working process of the zero point detection unit 5 is as follows:

[0032] When the AC power output by transformer 1 is in the negative half cycle, the voltage of the first AC output terminal AC0 of transformer 1 is lower than the voltage of the second AC output terminal AC1 of transformer 1. When the voltage difference between the second AC output terminal AC1 of transformer 1 and the first AC output terminal AC0 of transformer 1 is greater than the threshold voltage, transistor Q12 and Zener diode Z12 are turned on. Since transistor Q12 and transistor Q11 constitute a mirror current source, Q11 is also turned on. The collector current of transistor Q11 generates a voltage on resistors R11 and R12. The voltage is a high-level detection signal. In actual use, the detection signal can be obtained by detecting the voltage at the OUT terminal. The threshold voltage is determined by the conduction voltage drop of Zener diode Z12 and transistor Q12.

[0033] When the AC power output by the transformer 1 is in the positive half cycle, the voltage of the first AC output terminal AC0 of the transformer 1 is higher than the voltage of the second AC output terminal AC1. When the voltage difference between the first AC output terminal AC0 of the transformer 1 and the second AC output terminal AC1 of the transformer 1 is higher than the threshold voltage, the voltage zener diode Z11 and the transistor Q13 are turned on, and the current flowing into the transistor Q13 generates a voltage on the resistor R11, which is a high-level detection signal.

[0034] When the AC power output by transformer 1 is at the zero-crossing point and the difference between the voltage at the first AC output terminal AC0 of transformer 1 and the voltage at the second AC output terminal AC1 of transformer 1 is less than the threshold voltage, the voltage regulator diode Z12, transistor Q12, and transistor Q11 are not conducting, and the voltage regulator diode Z12 and transistor Q13 are also not conducting, there is no current on the resistor R11, and the OUT terminal is a low-level signal of 0V;

[0035] Therefore, the zero point of the alternating current output by the transformer 1 is determined by detecting the signal from a high level state to a low level state and from a low level state to a high level state, wherein when the detection signal changes from a high level state to a high level signal before the low level state, the MOS tubes M2 and M3 can be driven to be turned on, and when the detection signal changes from a low level state to a high level signal after the high level state, the MOS tubes M1 and M3 can be driven to be turned on, and when the detection signal is at a low level, the MOS tubes M1, M2, M3 and M4 are driven to be turned off.

[0036] Specifically, in this embodiment, in order to achieve signal isolation, the other end of the resistor R11 is connected as follows: Figure 4 The optical coupling isolation unit 7 shown sends a detection signal to the control unit 6 .

[0037] Specifically, the optocoupler isolation unit 7 includes a photocoupler U1, a resistor R20, a resistor R21 and a voltage conversion unit 70, the other end of the resistor R11 is electrically connected to pin 1 of the photocoupler U1, pin 2 of the photocoupler U1 is grounded through the resistor R20, and the voltage conversion unit 70 is electrically connected to the first DC output terminal DC0, and is used to convert the voltage at the first DC output terminal DC0 into a 5V voltage input to pin 4 of the photocoupler U1, pin 3 of the photocoupler is electrically connected to the control unit 6 through the resistor R21, and is grounded through the resistor R22; wherein the voltage conversion unit 70 can use an existing 24V-5V voltage conversion chip to perform voltage conversion.

[0038] In actual use, when the other end of the resistor R11 outputs a high-level signal, the diode on the primary side of the photocoupler U1 is turned on, the transistor on the secondary side of the photocoupler U1 is turned on, and the 5V voltage is input to the control unit 6. When the other end of the resistor R11 outputs a low-level signal, the diode on the primary side of the photocoupler U1 and the transistor on the secondary side of the photocoupler U1 are not turned on, and the control unit 6 inputs a low-level signal.

[0039] Specifically, in this embodiment, the control unit 6 is a single-chip microcomputer. The model of the single-chip microcomputer can be selected according to actual needs and is not limited here. The exemplary single-chip microcomputer can be an STM32 single-chip microcomputer or an stc89c52 single-chip microcomputer.

[0040] The above is based on the enlightenment of this utility model. Through the above description, relevant staff can make various changes and modifications without deviating from the technical idea of ​​this utility model. The technical scope of this utility model is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A switching power supply, characterized in that: It includes a transformer, a rectifier bridge based on MOS tube, a filter unit, a voltage stabilizing unit, a zero point detection unit and a control unit; The rectifier bridge includes a MOS tube M1, a MOS tube M2, a MOS tube M3 and a MOS tube M4; the drain of the MOS tube M1 is electrically connected to the drain of the MOS tube M3, which is a first DC connection terminal DC0 of the rectifier bridge; the source of the MOS tube M1 is electrically connected to the drain of the MOS tube M2, which is a first AC connection terminal AC10 of the rectifier bridge; the source of the MOS tube M3 is electrically connected to the drain of the MOS tube M4, which is a second AC connection terminal AC11 of the rectifier bridge; the source of the MOS tube M2 is electrically connected to the source of the MOS tube M4, which is a second DC connection terminal DC1 of the rectifier bridge; The transformer is used to convert the input 220V AC power into 24V AC power, the first AC output terminal and the second AC output terminal of the transformer are electrically connected to the first AC connection terminal AC10 and the second AC connection terminal AC11 of the rectifier bridge respectively, and the first DC connection terminal DC0 and the second DC connection terminal DC1 of the rectifier bridge are electrically connected to the filtering unit and the voltage stabilizing unit respectively; The zero point detection unit is electrically connected to the first AC output terminal and the second AC output terminal of the transformer, and is used to detect the zero point signal of the AC power output by the transformer, and input the detection signal to the control unit. Based on the detection signal, the control unit sends control signals for controlling the on and off of the MOS tubes M1, M2, M3 and M4 to the gates of the MOS tubes M1, M2, M3 and M4 respectively.

2. A switching power supply according to claim 1, characterized in that: The filtering unit includes a filtering capacitor, the first DC connection terminal DC0 is electrically connected to one end of the filtering capacitor, and the second DC connection terminal DC1 is electrically connected to the other end of the filtering capacitor.

3. A switching power supply according to claim 1, characterized in that: The voltage stabilizing unit includes a voltage stabilizing chip of model LM7824, a capacitor C1 and a capacitor C2, the input end of the voltage stabilizing chip is electrically connected to the first DC connection end DC0 and one end of the capacitor C1 respectively, the output end of the voltage stabilizing chip is electrically connected to one end of the capacitor C2, and the ground end of the voltage stabilizing chip, the other end of the capacitor C1 and the other end of the capacitor C2 are all electrically connected to the second DC connection end DC1.

4. A switching power supply according to claim 1, characterized in that: The zero point detection unit includes a transistor Q11, a transistor Q12, a transistor Q13, a voltage regulator diode Z11, a voltage regulator diode Z12, a resistor R10, a resistor R11 and a resistor R12, the emitter of the transistor Q11, the emitter of the transistor Q12 and the base of the transistor Q13 are respectively electrically connected to the first AC output end of the transformer, and the base of the transistor Q11 is respectively electrically connected to the base of the transistor Q12, the collector of the transistor Q12 and the negative electrode of the voltage regulator diode Z12. The emitter of the transistor Q13 is electrically connected to the positive electrode of the Zener diode Z11, the negative electrode of the Zener diode Z11 is electrically connected to the positive electrode of the Zener diode Z12 and one end of the resistor R10 respectively, the other end of the resistor R10 is electrically connected to the second AC output end of the transformer, the collector of the transistor Q11 and the collector of the transistor Q3 are both electrically connected to one end of the resistor R11, the other end of the resistor R11 is grounded through the resistor R12, and is electrically connected to the control unit, and sends a detection signal to the control unit.

5. A switching power supply according to claim 4, characterized in that: The other end of the resistor R11 sends a detection signal to the control unit through the optical coupling isolation unit.

6. A switching power supply according to claim 5, characterized in that: The optocoupler isolation unit includes a photocoupler U1, a resistor R20, a resistor R21 and a voltage conversion unit, the other end of the resistor R11 is electrically connected to pin 1 of the photocoupler U1, pin 2 of the photocoupler U1 is grounded through the resistor R20, the voltage conversion unit is electrically connected to the first DC connection terminal DC0, and is used to convert the voltage at the first DC connection terminal DC0 into a 5V voltage input to pin 4 of the photocoupler U1, pin 3 of the photocoupler is electrically connected to the control unit through the resistor R21, and is grounded through the resistor R22.

7. A switching power supply according to claim 1, characterized in that: The control unit is a single chip microcomputer.

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