CN103856063A - Series-parallel type double-active bridge circuit - Google Patents

Abstract

The invention discloses a series-parallel type double-active bridge circuit, belonging to the fields of power electronics and electrotechnology. The bridge circuit comprises a first double-active bridge circuit and a second double-active bridge circuit, wherein input sides of the first double-active bridge circuit and the second double-active bridge circuit are connected in series and are subsequently connected with a high-voltage input grid side; output sides of the first double-active bridge circuit and the second double-active bridge circuit are connected in parallel and are subsequently connected with a low-voltage output grid side. By means of a mode that the input sides are connected in series and the output sides are connected in parallel, the requirements on voltage resistance grade of a switch tube of a high-voltage side are alleviated, the heating of the switch tube is reduced, and therefore the conductive consumption of the overall circuit is reduced. Therefore, the bridge circuit is high in energy conversion efficiency in the situation of large voltage change, and the bridge circuit can be used as a direct current-direct current conversion circuit of a bidirectional charger for charging and discharging power of a low-voltage battery pack.

Description

A serial-parallel dual active bridge circuit

technical field

The invention relates to a DC-DC conversion circuit, in particular to a dual active bridge circuit, which belongs to the technical field of power electronics and electric engineering.

Background technique

There are mainly two types of DC-DC converters used in existing bidirectional charger circuits: 1) DC-DC bidirectional converters that are not electrically isolated, and 2) isolated DC-DC bidirectional converters. In the first method, most of the bidirectional half-bridge circuits are used. When the voltage of the battery pack is low in this circuit, the voltage becomes relatively large compared with the DC high voltage on the input side, which limits the voltage adjustment range and reduces the voltage. In addition, the electrical isolation between the battery and the DC bus has potential safety hazards. The second method mostly uses dual active bridge circuits. Because of the use of high-frequency isolation transformers, it solves the problems of voltage adjustment range and safety in the first method. , the voltage stress of the switch tube on the high-voltage side is relatively large, and a switch tube with a higher withstand voltage level must be selected, and the switch tube with a higher withstand voltage level has a relatively large conduction resistance or conduction voltage drop. The current stress is relatively large, and the switching tube generates more heat, so the efficiency of the system is still not high. Therefore, existing circuit topologies have disadvantages in applications with high transformation ratios.

Contents of the invention

The purpose of the present invention is to overcome the problem that the dual active bridge circuit in the prior art cannot be applied to occasions with a large voltage conversion ratio, and provide a series-parallel dual active bridge circuit, which reduces circuit energy consumption and improves conversion efficiency.

The purpose of the present invention is achieved in this way: a series-parallel dual active bridge circuit, comprising a first dual active bridge circuit and a second dual active bridge circuit, the first dual active bridge circuit and the second active bridge circuit The input side of the dual active bridge circuit is connected in series to the high voltage input network side, and the second dual active bridge circuit and the output side of the second dual active bridge circuit are connected in parallel to the low voltage output network side.

As a further limitation of the present invention, the on-off of the switches at the corresponding positions in the first dual active bridge circuit and the second dual active bridge circuit are synchronous, and the high voltage side and the low voltage side of each dual active bridge circuit The on-off of the diagonal switch tubes are all synchronous.

Compared with the prior art, the beneficial effect of the present invention is that the present invention connects two dual active bridge circuits to the high-voltage input grid side after being connected in series on the input side, and reduces the impact on the high-voltage side switching tube by means of series voltage division. The requirements of the withstand voltage level reduce the conduction loss. At the same time, the output side of the two dual active bridge circuits is connected to the low-voltage output network side after being connected in parallel. The conduction loss of the switch tube on the low-voltage side is reduced, thereby reducing the conduction loss of the overall circuit, which makes the present invention have higher energy conversion efficiency in the case of a large voltage change ratio, and has high safety and voltage adjustment range. The advantages of wide and high efficiency; in addition, the circuit in the present invention is symmetrical on both sides and can realize bidirectional flow of energy, so the invented circuit can be used as a DC-DC conversion circuit in a bidirectional charger to charge and discharge a low-voltage battery pack.

Description of drawings

Fig. 1 is a schematic diagram of the power supply of the present invention.

Fig. 2 The present invention is used as a schematic diagram of the main circuit in a bidirectional charger.

Fig. 3 is a driving timing diagram of the switch tube in the step-down state of the present invention.

Fig. 4 is a driving timing diagram of the switch tube in the boost state of the present invention.

Symbol names in Figure 1 and Figure 2:

VH input DC voltage;

VL output DC voltage;

Ci1, Ci2 high voltage side filter capacitor;

Q1～Q16 switch tube;

D1～D16 The body diode of the switching tube;

C1～C16 The parasitic capacitance of the switching tube;

Cb1, Cb2 DC blocking capacitor;

Ls1, Ls2 resonant inductance;

Tr1, Tr2 high frequency transformer;

Co1, Co2 output filter capacitor.

Symbol names in Figure 3 and Figure 4:

Q1～Q16 The driving signal of the switching tube;

Φ Phase shift angle.

Detailed ways

A kind of serial-parallel dual active bridge circuit as shown in Figure 1, comprises the first dual active bridge circuit and the second dual active bridge circuit, the first dual active bridge circuit and the second dual active bridge circuit The input side of the first dual active bridge circuit is connected to the high voltage input network side after being connected in series, the output side of the second dual active bridge circuit and the second dual active bridge circuit are connected in parallel and then connected to the low voltage output network side, the first dual active bridge circuit and the second dual active bridge circuit The switch tubes at the corresponding positions in the active bridge circuit are switched on and off synchronously, and the diagonal switch tubes on the high-voltage side and low-voltage side in each dual active bridge circuit are switched on and off synchronously, and the high-voltage input network side is the grid and AC. /DC circuit, the low-voltage output grid side is a battery. the

When the present invention works, the driving signals of the switching tubes of the same bridge arm are complementary and there is a dead zone. If the switch driving sequence as shown in Figure 3 is adopted, the phase shift angle of the switching tube on the high-voltage side ahead of the switching tube on the low-voltage side is Φ , the step-down mode operation of the circuit of the present invention from the high-voltage side to the low-voltage side can be realized. If the switch driving sequence shown in FIG. The boost mode operation of the invented circuit from the low voltage side to the high voltage side can be realized. Therefore, the inventive circuit in FIG. 1 can realize bidirectional transmission of energy through the control of the driving sequence as shown in FIG. 3 and FIG. 4 , and can improve the energy conversion efficiency in high voltage ratio applications.

As shown in Figure 2, the specific parameters of the inventive circuit are as follows: the maximum power of this circuit is 3.3KW, the DC bus voltage VH=400V, the high-voltage side capacitor Ci1=Ci2=3600μF, the low-voltage side capacitor Co1=Co2=2000μF, the high-voltage side switch tube Q1 ～Q4, Q9～Q12 adopt IXFK102N30P (300V/102A) of IXYS, low-voltage side switch tubes Q5～Q8, Q13～Q16 use Infineon IPP030N10N3 (100V/100A), D1～D16 and C1～C16 in the figure are switch tubes Body diode and junction capacitance, Ls1=Ls2=20μH, DC blocking capacitor Cb1=Cb2=4.4μF, high-frequency transformer Tr1 and Tr2 use EE55 cores, and the measured highest efficiency is 97.4%.

It can be seen from the above description that the circuit of the present invention has the following advantages:

(1) Energy conversion with high transformation ratio can be realized;

(2) Due to the high-voltage side series and low-voltage side parallel structure, the switching loss can be reduced and the efficiency is high;

(3) It is suitable for application in distributed photovoltaic power generation energy storage devices, energy recovery and bidirectional chargers for electric vehicles.

The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solutions disclosed in the present invention, those skilled in the art can make some replacements and modifications to some of the technical features according to the disclosed technical content without creative work. Deformation, these replacements and deformations are all within the protection scope of the present invention.

Claims (2)

1. a string-and the two active bridge circuits of type, comprise first pair of active bridge circuit and second pair of active bridge circuit, it is characterized in that, after the input side series connection of described first pair of active bridge circuit and second pair of active bridge circuit, be connected with high input voltage net side, after the outlet side parallel connection of second pair of active bridge circuit and second pair of active bridge circuit, be connected with low pressure output net side.

2. a kind of string according to claim 1-and the two active bridge circuits of type, it is characterized in that, in described first pair of active bridge circuit and second pair of active bridge circuit, the break-make of the switching tube of correspondence position is synchronous, and the diagonally opposing corner switching tube break-make of every a pair of active bridge circuit mesohigh side and low-pressure side is all synchronous.

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