CN211785741U - Switching power supply primary input voltage detection circuit - Google Patents
Switching power supply primary input voltage detection circuit Download PDFInfo
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- CN211785741U CN211785741U CN201922179221.0U CN201922179221U CN211785741U CN 211785741 U CN211785741 U CN 211785741U CN 201922179221 U CN201922179221 U CN 201922179221U CN 211785741 U CN211785741 U CN 211785741U
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Abstract
The utility model relates to a switch power supply primary input voltage detection circuit, which comprises a voltage acquisition unit, a voltage holding unit, a proportion operation unit and a power supply unit; the voltage acquisition unit is used for acquiring negative pulse voltage of the auxiliary source winding; the voltage holding unit is used for inputting the reverse pulse voltage of the auxiliary source winding to the reverse input end of the proportional operation unit; and the proportion operation unit is used for amplifying the proportion of the acquired voltage and inputting the amplified voltage to the voltage sampling end of the PWM controller. The utility model discloses whole circuit principle simple structure, the consumption is little, and the reliability is high, and occupation space is little, can convert the voltage that voltage sampling unit gathered to the required magnitude of voltage of controller through the proportional resistance who adjusts proportion arithmetic unit, and then realizes elementary input voltage's detection.
Description
Technical Field
The utility model relates to a power technology field, concretely relates to switching power supply primary input voltage detection circuit.
Background
The DC/DC converter with the switching power supply as the secondary power supply of the system is widely applied to military and civil electronic systems such as aerospace, aviation, ships, weapons, electronics, railways, communication, medical electronics, industrial automation equipment and the like. In the design of a high-voltage input switching power supply controlled by a secondary side, accurate detection of a primary side input voltage is important. In general, a large number of devices such as a sampling resistor, an amplifier, and an isolation device are used to detect the input voltage on the primary side. However, as electronic systems are miniaturized, the size of the power supply module is smaller and smaller, and the design requirements of the power supply module cannot be met by the traditional and complicated primary side input voltage detection mode.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a switching power supply primary input voltage detection circuitry can realize at the accurate quick detection primary side input voltage of power secondary side, for secondary side control circuit short-term test input voltage.
In order to achieve the above purpose, the utility model adopts the following technical scheme:
a primary input voltage detection circuit of a switching power supply comprises a voltage acquisition unit, a voltage holding unit, a proportion operation unit and a power supply unit;
the voltage acquisition unit is used for acquiring negative pulse voltage of the auxiliary source winding; the voltage holding unit is used for inputting the reverse pulse voltage of the auxiliary source winding to the reverse input end of the proportional operation unit; and the proportion operation unit is used for amplifying the proportion of the acquired voltage and inputting the amplified voltage to the voltage sampling end of the PWM controller.
As a further improvement of the above technical solution:
the voltage sampling unit comprises a sampling network upper resistor R1 and a sampling network lower resistor R2, one end of the sampling network upper resistor R1 is connected with the auxiliary source transformer winding and the power supply unit, the other end of the sampling network upper resistor R1 is connected with one end of the sampling network lower resistor R2, and the other end of the sampling network lower resistor R2 is connected with an output ground.
The voltage holding unit comprises a diode D2 and a capacitor C3, the anode of the diode D2 is connected with the inverting input end of the proportional operation unit, the cathode of the diode D2 is connected with the voltage sampling unit, one end of the capacitor C3 is connected with the anode of the diode D2, and the other end of the capacitor C3 is grounded.
The proportional operation unit comprises an operational amplifier U1, resistors R4, R5, R6 and a capacitor C5, wherein the inverting input end of the operational amplifier U1 is connected with one end of a resistor R4, the other end of the resistor R4 is connected with a voltage holding unit, the non-inverting input end of the operational amplifier U1 is connected with one end of a resistor R5, the other end of the resistor R5 is grounded, one end of a resistor R6 is connected with the inverting input end of the operational amplifier U1, the other end of a resistor R6 is connected with the output end of the operational amplifier U1, and the capacitor C5 is connected in parallel with the two ends of the resistor R6.
The power supply unit comprises a rectifying tube D1, a filter capacitor C2, a peak absorption resistor R3 and a peak absorption capacitor C4; the positive pole of rectifier tube D1 is connected with auxiliary transformer winding, and rectifier tube D1's negative pole is connected with filter capacitor C2's one end, and filter capacitor C2's other end ground connection, peak absorbing resistance R3's one end and rectifier tube D1 positive pole are connected, and peak absorbing resistance R3's the other end is through peak absorbing capacitance C4 ground connection.
According to the above technical scheme, switching power supply primary input voltage detection circuitry gather voltage holding capacitance with auxiliary source winding negative voltage pulse value, this voltage value is directly proportional to primary input voltage value, can calculate primary input voltage value through this voltage value, auxiliary source winding turn ratio, sampling network's resistance value and proportion operation resistance value. The whole circuit principle has simple structure, low power consumption, high reliability and small occupied space; the voltage collected by the voltage sampling unit can be converted into a voltage value required by the controller by adjusting the proportional resistor of the proportional operation unit, and further the detection of the primary input voltage is realized. In addition, the amplification factor of the proportional operation unit is easy to calculate and adjust, and the applicability of the circuit can be improved by adjusting the proportional resistor.
Drawings
Fig. 1 is a circuit block diagram of the present invention;
fig. 2 is a schematic circuit diagram of the present invention.
Detailed Description
The present invention will be further explained with reference to the accompanying drawings:
as shown in fig. 1, the primary input voltage detection circuit of the switching power supply of the present embodiment includes a voltage acquisition unit 1, a voltage holding unit 2, a proportional operation unit 3, a capacitor C1, and a power supply unit 4; one end of the capacitor C1 is connected to the output end of the power supply unit 4, and the other end of the capacitor C1 is connected to the output ground.
The input end of the voltage sampling unit 1 is connected with the auxiliary source winding, and the output end of the voltage sampling unit is connected with the input end of the voltage holding unit 2, and the voltage sampling unit is used for collecting the negative voltage pulse value of the auxiliary source winding and sending the negative voltage pulse value into the voltage holding unit 2.
The input end of the voltage holding unit 2 is connected with the output end of the voltage sampling unit 1, the output end of the voltage holding unit 2 is connected with the inverted input end of the proportional operation unit 3, and the voltage holding unit is used for holding the collected pulse voltage and sending the pulse voltage to the proportional operation unit for proportional operation processing.
The inverting input end of the proportional operation unit 3 is connected with the output end of the voltage holding unit 2, the homodromous input end of the proportional operation unit 3 is connected with the power supply unit 4 and the decoupling capacitor C1, the output end of the proportional operation unit 3 is connected with the voltage sampling end of the PWM controller, and the proportional operation unit is used for sending the collected voltage into the controller after proportional operation to realize related control
As shown in fig. 2, the voltage sampling unit of this embodiment is composed of a sampling network upper resistor R1 and a sampling network lower resistor R2, one end of the sampling network upper resistor R1 is connected to the auxiliary source transformer winding and the power supply unit 4, the other end of the sampling network upper resistor R1 is connected to one end of the sampling network lower resistor R2, and the other end of the sampling network lower resistor R2 is connected to the output ground.
The voltage holding unit 2 is composed of a diode D2 and a capacitor C3, wherein the anode of the diode D2 is connected to the inverting input terminal of the proportional operation unit 3, the cathode of the diode D2 is connected to the node between the network resistor R1 and the sampling network lower resistor R2, one end of the capacitor C3 is connected to the anode of the diode D2, and the other end of the capacitor C3 is grounded.
The proportional operation unit 3 comprises an operational amplifier U1, resistors R4, R5 and R6 and a capacitor C5, wherein the inverting input end of the operational amplifier U1 is connected with one end of a resistor R4, the other end of the resistor R4 is connected with the anode of a diode D2, the non-inverting input end of an operational amplifier U1 is connected with one end of the resistor R5, the other end of the resistor R5 is grounded, one end of the resistor R6 is connected with the inverting input end of the operational amplifier U1, the other end of the resistor R6 is connected with the output end of the operational amplifier U1, and the capacitor C5 is connected in parallel with the two ends of the resistor R6.
The power supply unit 4 consists of a rectifier tube D1, a filter capacitor C2, a peak absorption resistor R3 and a peak absorption capacitor C4; the anode of the rectifier tube D1 is connected with the auxiliary transformer winding, the cathode of the rectifier tube D1 is connected with one end of the filter capacitor C2, the other end of the filter capacitor C2 is grounded, one end of the peak absorption resistor R3 is connected with the anode of the rectifier tube D1, and the other end of the peak absorption resistor R3 is grounded through the peak absorption capacitor C4.
The working principle is as follows: when the auxiliary source works normally, on one hand, forward pulses on the auxiliary source winding are rectified and filtered by D1 and C2 and then converted into direct-current output voltage, and the direct-current output voltage is used for providing stable direct-current voltage for the proportional operation unit 3.
On the other hand, the voltage sampling unit 1 collects the negative voltage pulse value on the auxiliary source winding, scales the pulse value according to the proportional relation of the resistance values of R1 and R2, and transmits the scaled voltage pulse value to the voltage holding capacitor C3 through D2. After passing through the diode D2 and the capacitor C3, the scaled voltage pulses are converted to a negative dc voltage, which is input to the inverting input of the proportional unit 3 for processing by the inverting proportional operational amplifier U1, and after passing through the inverting proportional operational amplifier U1, a proportional positive voltage is generated at the output of the amplifier U1. The forward voltage is finally transmitted to a voltage sampling end of the PWM controller, and the PWM controller can calculate a primary input voltage value through an auxiliary source turn ratio and through the resistance values of the resistors R1 and R2 and the proportional operation relation of the proportional operation unit 3.
The input voltage detection circuit is suitable for various isolated switching power supplies or DC/DC converters, is particularly suitable for high-voltage input occasions controlled by the secondary side, can quickly and accurately detect the primary measured input voltage on the secondary side, has few required components and parts, low power consumption, safety and reliability, and is favorable for reducing the size of a power supply module. The primary side voltage is detected quickly and accurately, so that the converter can respond quickly, the reliability of the converter is improved, and the system safety is guaranteed.
The above-mentioned embodiments are only for describing the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art without departing from the design spirit of the present invention should fall into the protection scope defined by the claims of the present invention.
Claims (5)
1. A switching power supply primary input voltage detection circuit is characterized in that: the device comprises a voltage acquisition unit, a voltage holding unit, a proportion operation unit and a power supply unit;
the voltage acquisition unit is used for acquiring negative pulse voltage of the auxiliary source winding;
the voltage holding unit is used for inputting the reverse pulse voltage of the auxiliary source winding to the reverse input end of the proportional operation unit;
and the proportion operation unit is used for amplifying the proportion of the acquired voltage and inputting the amplified voltage to the voltage sampling end of the PWM controller.
2. The switching power supply primary input voltage detection circuit of claim 1, wherein: the voltage acquisition unit comprises a sampling network upper resistor R1 and a sampling network lower resistor R2, one end of the sampling network upper resistor R1 is connected with the auxiliary source transformer winding and the power supply unit, the other end of the sampling network upper resistor R1 is connected with one end of the sampling network lower resistor R2, and the other end of the sampling network lower resistor R2 is connected with an output ground.
3. The switching power supply primary input voltage detection circuit of claim 1, wherein: the voltage holding unit comprises a diode D2 and a capacitor C3, the anode of the diode D2 is connected with the inverting input end of the proportional operation unit, the cathode of the diode D2 is connected with the voltage sampling unit, one end of the capacitor C3 is connected with the anode of the diode D2, and the other end of the capacitor C3 is grounded.
4. The switching power supply primary input voltage detection circuit of claim 1, wherein: the proportional operation unit comprises an operational amplifier U1, resistors R4, R5, R6 and a capacitor C5, wherein the inverting input end of the operational amplifier U1 is connected with one end of a resistor R4, the other end of the resistor R4 is connected with a voltage holding unit, the non-inverting input end of the operational amplifier U1 is connected with one end of a resistor R5, the other end of the resistor R5 is grounded, one end of a resistor R6 is connected with the inverting input end of the operational amplifier U1, the other end of a resistor R6 is connected with the output end of the operational amplifier U1, and the capacitor C5 is connected in parallel with the two ends of the resistor R6.
5. The switching power supply primary input voltage detection circuit of claim 1, wherein: the power supply unit comprises a rectifying tube D1, a filter capacitor C2, a peak absorption resistor R3 and a peak absorption capacitor C4; the positive pole of rectifier tube D1 is connected with auxiliary transformer winding, and rectifier tube D1's negative pole is connected with filter capacitor C2's one end, and filter capacitor C2's other end ground connection, peak absorbing resistance R3's one end and rectifier tube D1 positive pole are connected, and peak absorbing resistance R3's the other end is through peak absorbing capacitance C4 ground connection.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922179221.0U CN211785741U (en) | 2019-12-06 | 2019-12-06 | Switching power supply primary input voltage detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922179221.0U CN211785741U (en) | 2019-12-06 | 2019-12-06 | Switching power supply primary input voltage detection circuit |
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| CN211785741U true CN211785741U (en) | 2020-10-27 |
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| CN201922179221.0U Active CN211785741U (en) | 2019-12-06 | 2019-12-06 | Switching power supply primary input voltage detection circuit |
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| CN (1) | CN211785741U (en) |
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