CN202488350U - Flyback switching power supply circuit suitable for photovoltaic system - Google Patents

Abstract

The utility model discloses a fly-back switching power supply circuit suitable for a photovoltaic system, comprising a power-on power supply circuit, a PWM control circuit with voltage-current feedback, a MOSFET gate drive protection circuit, a fly-back converter, an RC absorption circuit and an auxiliary power supply circuit. The fly-back switching power supply circuit of the utility model has a reliable structure. The power-on power supply circuit accesses a voltage detection unit, allowing a power supply to act only when the input voltage energy is high enough to maintain normal operation of the system, so that the problem is solved of frequency start/stop (hiccup) of a switching power supply during low light conditions in the morning and evening, the power supply and the system are protected from being damaged, and the reliability of the power supply is enhanced.

Description

Flyback switching power supply circuit suitable for photovoltaic system

technical field

The utility model relates to a flyback switching power supply, in particular to a flyback switching power supply circuit suitable for powering a control circuit in the field of photovoltaic power generation. the

Background technique

The development of power electronics technology and photovoltaic technology has made photovoltaic grid-connected power generation a reality, and the characteristic of photovoltaic power generation is that it must be able to generate electricity when there is sufficient sunlight during the day. the

In order to prevent photovoltaic power generation equipment (photovoltaic inverter) from consuming mains power at night, the method of taking power from the DC side is generally adopted in the design of low-power photovoltaic inverters, but due to the fact that photovoltaic panels output energy under weak light conditions The reason is that if the traditional design is adopted, the switching power supply will start and stop frequently (hiccups). the

In order to solve this problem, many inverter designs now use the reverse rectification function of the inverter circuit to delay cutting off the power grid under the condition that the light cannot reach continuous power generation, and maintain the switching power supply with the reverse power supply of the power grid to avoid The switching power supply starts and stops repeatedly. But the disadvantage of this is that in the morning and evening when the light is weak, the inverter will consume the power of the grid, resulting in waste. the

Utility model content

The purpose of the utility model is to provide a flyback switching power supply with stable performance, low cost, and not easy to repeatedly start and stop under weak light conditions. the

The technical scheme of the utility model is as follows:

A flyback switching power supply circuit suitable for photovoltaic systems, including a power supply start-up power supply circuit, a PWM control circuit with voltage and current feedback, a MOSFET gate drive protection circuit, a flyback converter, an RC snubber circuit and an auxiliary power supply circuit , it is characterized in that: the power supply start-up power supply circuit includes Zener diodes D1 and D2 in series, the cathodes of D1 and D2 of the Zener diodes are connected to the positive pole of the input power supply, and the anodes of the Zener diodes D1 and D2 are connected via The pull-down resistors R2~R4 connected in series in series are connected to the negative pole of the input power supply;

The PWM control circuit with voltage and current feedback includes a control circuit U1 and resistors R9~R11, the high voltage input terminal of the control circuit U1 is connected in series with the current limiting resistor R1 and connected to the Zener diode D2 in the power supply circuit The terminal between the pull-down resistor R2, the COMP terminal of the control circuit U1 is externally connected to the main output circuit of the switching power supply through the optocoupler OP1, and the OUT terminal of the control circuit U1 is used as the output terminal of the PWM control circuit with voltage and current feedback, and connected to the MOSFET gate drive protection circuit; the resistors R9~R11 are connected in parallel to form a current sampling resistor;

The MOSFET gate drive protection circuit includes a gate resistor R6, a gate pull-down resistor R7 and a Zener diode ZD1, and the flyback converter is composed of a chopper MOSFET Q1 and a flyback transformer TR1A, wherein the gate resistor R6 is connected between the output terminal of the control circuit U1 and the gate of the chopper MOSFET Q1, the gate pull-down resistor R7 is connected between the gate of the chopper MOSFET Q1 and the negative terminal of the input power supply of the chopper MOSFET Q1, and the Zener diode ZD1 is connected in parallel with gate pull-down resistor R7;

The RC type absorption circuit comprises a fast recovery diode D7, an RC parallel circuit composed of a resistor R5 and a capacitor C10 connected in parallel, wherein the fast recovery diode D7 is connected between the drain of the chopping MOSFET Q1 and one end of the RC parallel circuit, The other end of the RC parallel circuit is connected to the positive pole of the input power supply of the chopper MOSFET Q1;

The auxiliary power supply circuit includes a rectifier diode D3, the positive pole of the rectifier diode D3 is connected to the primary coil terminal of the flyback transformer TR1A, and the negative pole of the rectifier diode D3 is sequentially connected in parallel with a high-frequency capacitor C3 and an electrolytic capacitor C2 to form a first-stage auxiliary power supply , and then connect the diode D6 and the electrolytic capacitor C9 in series to form the second auxiliary power supply.

The flyback switching power supply circuit suitable for photovoltaic systems is characterized in that: the power supply startup power supply circuit is a current-limiting power supply circuit with a Zener diode voltage detection unit, and is also a dual side network. the

The beneficial effects of the utility model:

The circuit structure of the utility model is reliable, aiming at the low energy output voltage of the photovoltaic panel when the light is weak, a voltage detection unit is added to the power supply circuit of the switching power supply, so that the power supply can maintain the normal operation of the system only when the input voltage energy is high enough This solves the problem of frequent start-stop (hiccup) of the switching power supply when the light is weak in the morning and evening, and protects the power supply itself and the system from damage; Optimization and improvement have improved the reliability of the power supply.

Description of drawings

Fig. 1 is the schematic circuit diagram of the utility model. the

Detailed ways

See Figure 1, a flyback switching power supply circuit suitable for photovoltaic systems, including a power supply start-up power supply circuit, a PWM control circuit with voltage and current feedback, a MOSFET gate drive protection circuit, a flyback converter, and an RC-type snubber circuit And the auxiliary power supply circuit, the power supply start-up power supply circuit includes series-connected Zener diodes D1 and D2, the cathodes of Zener diodes D1 and D2 are connected to the positive pole of the input power supply, and the anodes of Zener diodes D1 and D2 are sequentially connected in series through pull-down resistors R2~R4 are connected to the negative pole of the input power supply;

The PWM control circuit with voltage and current feedback includes a control circuit U1 and resistors R9~R11. The high-voltage input terminal of the control circuit U1 is connected in series with the current-limiting resistor R1 and then connected to the power supply to start the voltage between the Zener diode D2 and the pull-down resistor R2 in the power supply circuit. The terminal provides starting power for the control circuit U1. The COMP terminal of the control circuit U1 is connected to the main output circuit of the switching power supply through the optocoupler OP1 to provide a voltage loop feedback signal for the PWM control circuit with voltage and current feedback. The OUT terminal of the control circuit U1 serves as The output terminal of the PWM control circuit with voltage and current feedback is connected to the MOSFET gate drive protection circuit. The current feedback signal of the PWM control circuit with voltage and current feedback is taken from the chopping current of the MOSFET gate drive protection circuit; resistor R9~ R11 is connected in parallel to form a current sampling resistor, and its sampling value is used as a current loop feedback signal of PWM control with voltage and current feedback to provide the control circuit U1;

The MOSFET gate drive protection circuit includes gate resistor R6, gate pull-down resistor R7 and Zener diode ZD1. The flyback converter is composed of chopper MOSFET Q1 and flyback transformer (multi-winding choke coil) TR1A, where the gate Resistor R6 is connected between the output terminal of the control circuit U1 and the gate of the chopper MOSFET Q1, and the gate pull-down resistor R7 is connected between the gate of the chopper MOSFET Q1 and the negative terminal of the input power supply of the chopper MOSFET Q1. The diode ZD1 is connected in parallel with the gate pull-down resistor R7, so that the protection function of the MOSFET gate drive protection circuit is realized with extremely simple and cheap circuit components;

The RC snubber circuit includes a fast recovery diode D7, an RC parallel circuit composed of a resistor R5 and a capacitor C10 connected in parallel, wherein the fast recovery diode D7 is connected between the drain of the chopper MOSFET Q1 and one end of the RC parallel circuit, and the RC parallel circuit The other end of the chopper MOSFET Q1 is connected to the positive input power supply, which can effectively absorb the magnetic leakage energy storage of the flyback transformer;

The auxiliary power supply circuit includes a rectifier diode D3. The anode of the rectifier diode D3 is connected to the primary coil terminal of the flyback transformer TR1A. The cathode of the rectifier diode D3 is connected in parallel with a high-frequency capacitor C3 and an electrolytic capacitor C2 to form a first-stage auxiliary power supply. Diode D6 and electrolytic capacitor C9 are connected in series to form the second auxiliary power supply, so that the power supply can be started quickly and stably.

In the utility model, the power starting power supply circuit is a current-limiting power supply circuit with a Zener diode voltage detection unit, and is also a double-terminal network with three connection terminals. the

Claims (2)

1. the inverse-excitation type switch power-supply circuit of a suitable photovoltaic system; The pwm control circuit, MOSFET gate-drive protective circuit, inverse excitation type converter, the RC formula that include power initiation power supply circuits, current feedback with voltage absorb circuit and auxiliary power circuit; It is characterized in that: described power initiation power supply circuits comprise voltage stabilizing didoe D1, the D2 that is in series; The D1 of said voltage stabilizing didoe, the negative electrode of D2 connect the positive pole of input power supply, and the D1 of voltage stabilizing didoe, the anode of D2 are connected to the negative pole of input power supply through the pull down resistor R2 ~ R4 of series connection successively;

The pwm control circuit of described current feedback with voltage comprises control circuit U1 and resistance R 9 ~ R11; Voltage stabilizing didoe D2 behind the high voltage input terminal series limiting resistor R1 of said control circuit U1 in the said power initiation power supply circuits of access and the terminals between the pull down resistor R2, said control circuit U1's COMPEnd is through optocoupler OP1 outside connected switch power supply master output circuit, and the OUT of said control circuit U1 end is as the output of the pwm control circuit of current feedback with voltage, and access MOSFET gate-drive protective circuit; Described resistance R 9 ~ R11 parallel connection constitutes current sampling resistor;

Described MOSFET gate-drive protective circuit comprises gate electrode resistance R6, gate pole pull down resistor R7 and voltage stabilizing didoe ZD1; Described inverse excitation type converter is made up of copped wave MOSFET Q1 and anti-violent change depressor TR1A; Wherein gate electrode resistance R6 is connected across between the gate pole of control circuit U1 output and copped wave MOSFET Q1; Gate pole pull down resistor R7 is connected across between the input power cathode of gate pole and copped wave MOSFET Q1 of copped wave MOSFET Q1, and voltage stabilizing didoe ZD1 is parallelly connected with gate pole pull down resistor R7;

Described RC formula absorbs the RC parallel circuits that circuit comprises fast recovery diode D7, composed in parallel by resistance R 5 and capacitor C 10; Wherein fast recovery diode D7 is connected across between the end of drain electrode and RC parallel circuits of copped wave MOSFET Q1, and the other end of RC parallel circuits inserts the input positive source of copped wave MOSFET Q1;

Described auxiliary power circuit comprises rectifier diode D3; The positive pole of rectifier diode D3 connects the primary coil terminals of anti-violent change depressor TR1A; The negative pole of rectifier diode D3 is parallel with high frequency capacitance C3 and electrochemical capacitor C2 successively; Constitute first order accessory power supply, and then series diode D6 and electrochemical capacitor C9, constitute second level accessory power supply.

2. the inverse-excitation type switch power-supply circuit of suitable photovoltaic system according to claim 1; It is characterized in that: described power initiation power supply circuits are the current limliting power supply circuits that have the voltage stabilizing didoe voltage detection unit, also are two-ports with three splicing ears simultaneously.