CN203039579U - High gain voltage-multiplying structure active lossless clamp converter - Google Patents

Abstract

An active lossless clamp converter with a high-gain voltage doubler structure, including a main switch tube, a clamp switch tube, a freewheeling diode, an output diode, a clamp capacitor, a voltage doubler capacitor, an output capacitor and A coupled inductor with two windings, the utility model uses the coupled inductor to expand the voltage gain of the converter and reduce the voltage stress of the power switch tube and diode, and uses the leakage inductance of the coupled inductor to realize the zero-voltage turn-on of the switch tube and suppress the diode The reverse recovery current, the clamp circuit composed of the clamp switch tube and the clamp capacitor can effectively absorb the voltage peak when the main switch tube is turned off and realize the lossless transfer of energy, and the gain of the converter is further improved by using the voltage doubler circuit , and further reduce the voltage stress of the power switch tube and the output diode, the circuit structure is simple, the control is convenient, and it is suitable for low-power, high-gain and high-efficiency photovoltaic grid-connected power generation conversion occasions.

Description

A High Gain Voltage Doubling Structure Active Lossless Clamp Converter

technical field

The utility model relates to a DC-DC converter and its application, in particular to an active non-destructive clamp converter with a high-gain voltage doubler structure. the

Background technique

In the solar power generation system, since the output voltage of a single solar cell is low, and the voltage required for inverter grid-connected power generation is relatively high, a first-stage DC-DC converter is required to convert low-voltage DC power into a high voltage suitable for grid-connected power generation. Voltage DC. In the distributed solar power generation scheme, the power capacity of a single solar cell is small, but the requirement for efficiency is high. Therefore, how to realize a single-phase single-stage converter with high gain, high efficiency and simple structure is of great significance for promoting the development of the photovoltaic industry. the

The voltage gain of the conventional single-phase single-transistor boost (Boost) DC-DC converter is only determined by the duty cycle, the voltage gain is limited, and it is difficult to meet the conversion requirements of high gain. The voltage stress of the power switching tube is relatively large, and it is difficult to reduce the conduction loss by using a low-voltage high-performance switching tube. Moreover, the converter works in a hard switching state, and the switching loss is relatively large. In order to realize the soft switching action of the Boost converter, in recent years, some soft switching schemes by adding active power switches or passive devices have been studied successively. Although these circuits realize the soft switching action, they cannot reduce the voltage stress of the switching tube. High-gain conversion of the system cannot be realized either. In order to increase the voltage gain of the converter, one solution is to use switched capacitors, but this solution requires a large number of switch tubes, which increases the system cost; another solution is to use a complex three-winding coupled inductor solution. The disadvantage of the scheme is that the structure of the coupled inductor is complex, which is not conducive to industrial processing, and it is difficult to ensure the consistency of the circuit. the

Contents of the invention

The utility model overcomes the shortcomings of conventional single-phase single-tube DC-DC converters such as low voltage gain, large conduction loss and high switching power consumption, and provides a high-gain voltage multiplier with simple structure, convenient control and no energy loss Structure active lossless clamp converter. the

In the high-gain voltage doubler structure active non-destructive clamp converter described in the utility model, the first end of the first winding of the coupling inductor is connected to the positive pole of the power supply, and the second end of the first winding is connected to the drain and clamp of the main switching tube. The source of the position switch is connected, the drain of the clamp switch is connected with the first end of the clamp capacitor and the anode of the freewheeling diode, the source of the main switch is connected with the negative pole of the power supply and the second end of the clamp capacitor ;

The first end of the second winding of the coupled inductor is connected to the positive pole of the power supply, the second end of the second winding of the coupled inductor is connected to the first end of the voltage doubler capacitor, the second end of the voltage doubler capacitor is connected to the cathode of the freewheeling diode, and the coupled inductor The second winding and the first winding of the coupled inductor are both two windings in a coupled inductor, with the first end of the first winding and the first end of the second winding being the end of the same name of the coupled inductor;

The anode of the output diode is connected to the cathode of the freewheeling diode, the cathode of the output diode is connected to the first end of the output capacitor, and the second end of the output capacitor is connected to the first end of the clamping capacitor. the

In the converter described above, one or more of the freewheeling diodes and the output diodes are replaced with synchronous rectifiers, all of which can work normally. the

When the converter of the utility model is working, the transformer effect of the coupled inductance is used to expand the voltage gain of the converter, reduce the voltage stress of the power switch tube and the diode, and reduce the conduction loss of the power device. The introduction of the voltage doubler circuit unit further improves the voltage gain of the circuit and reduces the voltage stress of the device; the leakage inductance of the coupled inductor is used to realize the zero-voltage turn-on of the power switch tube; at the same time, the leakage inductance of the coupled inductor is used to realize the freewheeling diode and the soft turn-off of the output diode; use the clamp switch tube and clamp capacitor to absorb the energy of the leakage inductance, so that there is no voltage spike when the main switch tube is turned off, and the absorbed leakage inductance energy is finally transmitted to the load to realize lossless absorption; The circuit structure is simple, the control is convenient, and it is suitable for distributed photovoltaic grid-connected power generation occasions with low power, high gain and high efficiency. the

The utility model has the advantages of no need for additional power switches and inductance elements, less accessory elements, simple structure, convenient control, no energy loss elements in the circuit, which can improve the efficiency of the circuit, and the power switch tube is turned off during the commutation process There is no voltage overshoot when the freewheeling diode is turned on; the coupled inductor transfers energy when the corresponding switch tube is turned on and off, which improves the utilization rate of the coupled inductor and reduces the volume of the coupled inductor. the

Description of drawings

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

Detailed ways

Referring to Fig. 1, in the high-gain voltage doubler structure active lossless clamp converter of the present invention, the first end of the coupling inductor first winding _L1 is connected to the positive pole of the power supply Vin, and the second end of the first winding _L1 is connected to the positive pole of the power supply Vin. The drain of the main switching tube S is connected to the source of the clamping switching tube Sc, the drain of the clamping switching tube Sc is connected to the first end of the clamping capacitor Cc and the anode of the freewheeling diode Dr, and the source of the main switching tube S The pole is connected to the negative pole of the power supply Vin and the second end of the clamping capacitor Cc;

The first end of the coupled inductor second winding _L2 is connected to the positive pole of the power supply Vin, the second end of the coupled inductor second winding _L2 is connected to the first end of the voltage doubler capacitor Cm, and the second end of the voltage doubler capacitor Cm is connected to the freewheeling current The cathode of the diode Dr is connected, the second winding L ₂ of the coupled inductor and the first winding L ₁ of the coupled inductor are two windings in a coupled inductor, the first winding L ₁ and the second winding L are marked by "*" in the figure the same-named end of ₂ ;

The anode of the output diode Do is connected to the cathode of the freewheeling diode Dr, the cathode of the output diode Do is connected to the first end of the output capacitor Co, and the second end of the output capacitor Co is connected to the first end of the clamping capacitor Cc. the

The voltage of the output capacitor Co is Vout, and the energy is finally transferred to the load Ro. the

The active lossless clamping converter with high-gain voltage doubling structure has six working processes in one switching cycle, that is, the commutation between the main switch S being turned off and the body diode of the clamping switch Sc being turned on; the freewheeling diode Dr The commutation between the shutdown and the conduction of the output diode Do; the conduction process of the clamp switch Sc; the commutation between the shutdown of the clamp switch Sc and the turn-on of the body diode of the main switch S; the shutdown of the output diode Do The commutation process between turning on the main switch tube S; the conduction process of the freewheeling diode Dr. the

The commutation between the turn-off of the main switch S and the turn-on of the body diode of the clamp switch Sc:

Before commutation, the circuit is in a stable working state where the main switch tube S and the freewheeling diode Dr are turned on, and the clamp switch tube Sc and the output diode Do are turned off. When the main switching tube S is turned off, due to the capacitance between the drain and the source of the main switching tube S, the main switching tube S turns off at zero voltage, and then the voltage on the main switching tube S rises rapidly, and the clamping switching tube Sc The voltage at the end of the main switching tube S drops rapidly to zero, and the body diode of the clamping switching tube Sc is turned on. Due to the effect of the clamping capacitor Cc, the voltage at both ends of the main switching tube S is clamped to a certain voltage value, and the clamping off of the main switching tube S is realized. broken. the

The commutation between the turn-off of the freewheeling diode Dr and the turn-on of the output diode Do:

After the body diode of the clamping switch Sc is turned on, the voltage on the clamping capacitor Cc starts to rise from a certain value, the leakage inductance energy of the coupling inductance is transferred to the clamping capacitor Cc, and the current of the freewheeling diode Dr drops linearly to Zero, the freewheeling diode Dr is turned off. And the voltage across the output diode Do drops linearly to zero, the output diode Do is turned on, and the energy begins to transfer to the output end. The circuit enters into a stable working state in which the main switch S and the freewheeling diode Dr are turned off, and the body diode of the clamp switch Sc and the output diode Do are turned on. the

The opening process of the clamp switch tube Sc:

After the output diode Do is turned on, the body diode of the clamp switch Sc is also turned on, and the voltage across the clamp switch Sc drops to zero. At this time, the gate signal of the clamp switch Sc is given, and the clamp switch Sc Sc realizes zero-voltage turn-on. The leakage inductance of the coupled inductor resonates with the clamping capacitor Cc, and energy is transferred between the two. The energy is transferred from the voltage doubler capacitor Cm to the load Ro through the second winding of the coupling inductor. The circuit enters into a stable working state where the main switch tube S and the freewheeling diode Dr are turned off, and the clamp switch tube Sc and the output diode Do are turned on. the

The commutation process between the clamp switch Sc being turned off and the body diode of the main switch S being turned on:

The clamping switch Sc is turned off, and due to the parasitic capacitance between the drain and the source of the clamping switch Sc, the clamping switch Sc realizes zero-voltage turn-off. After the clamp switch tube Sc is turned off, the leakage inductance of the coupled inductor starts to extract the energy on the capacitance between the drain and the source of the main switch S. When the energy on the capacitor is exhausted, the body diode of the main switch S is turned on. the

The commutation process between the turn-on of the main switch S and the turn-off of the output diode Do:

The gate signal of the main switch S is given. Since the body diode of the main switch S has been turned on, the main switch S is turned on with zero voltage, the current of the main switch S rises linearly with a certain slope, and the current of the output diode Do Decrease linearly with a certain slope, when the current of the output diode Do drops to zero, the output diode Do is turned off, realizing the commutation between the output diode Do off and the main switch S on, reducing the output diode Do reverse recovery loss. the

The conduction process of the freewheeling diode Dr:

After the main switch S is turned on and the output diode Do is turned off, the coupling inductor works in the forward transformer state, the voltage across the freewheeling diode Dr drops linearly to zero, the freewheeling diode Dr is turned on, and the energy begins to transfer to the voltage doubler capacitor Cm. The circuit enters into a stable working state where the main switch tube S and the freewheeling diode Dr are turned on, and the clamp switch tube Sc and the output diode Do are turned off. the

Claims (2)

1. active nondestructive clamping converter of high-gain times laminated structure is characterized in that:

The coupling inductance first winding (L ₁) first end link to each other the first winding (L with the positive pole of power supply (Vin) ₁) second end link to each other with the drain electrode of main switch (S) and the source electrode of clamp switch pipe (Sc), the drain electrode of clamp switch pipe (Sc) links to each other with first end of clamping capacitance (Cc) and the anode of fly-wheel diode (Dr), and the negative pole of the source electrode of main switch (S) and power supply (Vin) and second end of clamping capacitance (Cc) link to each other;

The coupling inductance second winding (L ₂) first end link to each other the coupling inductance second winding (L with the positive pole of power supply (Vin) ₂) second end links to each other with first end of multiplication of voltage electric capacity (Cm), second end of multiplication of voltage electric capacity (Cm) links to each other with the negative electrode of fly-wheel diode (Dr), the coupling inductance second winding (L ₂) and the coupling inductance first winding (L ₁) be all two windings in the coupling inductance, with the first winding (L ₁) first end and the second winding (L ₂) first end be the end of the same name of coupling inductance;

The anode of output diode (Do) links to each other with the negative electrode of fly-wheel diode (Dr), and the negative electrode of output diode (Do) links to each other with first end of output capacitance (Co), and second end of output capacitance (Co) links to each other with first end of clamping capacitance (Cc).

2. the active nondestructive clamping converter of high-gain as claimed in claim 1 times laminated structure is characterized in that, the one or more synchronous rectifiers that make in fly-wheel diode (Dr) and the output diode (Do) all can operate as normal.

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