CN102231599A - Four-port direct-current converter and control method thereof - Google Patents

Abstract

The invention discloses a four-port DC converter and a control method thereof, belonging to the technical field of power electronic converters. The four ports of the four-port DC converter are respectively connected to the first input source, the second input source, the storage battery and the load, wherein the load end is electrically isolated from the other three ports through a transformer, and the control method can simultaneously realize the converter Power control for four ports. It is characterized in that the power management and control of the first input source, the second input source, the battery and the load are simultaneously realized through one converter, and the functions of multiple single-input and single-output converters are realized; The solution has the following advantages: the number of switching devices and related control circuits is reduced, the cost, volume and weight of the circuit are reduced, device loss is reduced, conversion efficiency is improved, the entire converter is uniformly controlled, and power can be realized more effectively Management and improved system stability and reliability.

Description

A four-port DC converter and its control method

technical field

The invention relates to a four-port DC converter in a power converter and a control method thereof, belonging to the technical field of power electronic converters, in particular to the technical field of power converters in new energy power generation technology.

Background technique

With the increasingly serious energy crisis and environmental pollution, thermoelectric generator, solar energy, wind energy, fuel cell power generation and other new energy power generation technologies have become the focus of attention and research around the world.

There are some inherent defects in new energy power generation equipment: the output power of power generation equipment is affected by environmental conditions, and the output power changes randomly and is discontinuous and unstable. Therefore, independent new energy power generation equipment cannot independently, stably and reliably supply power to the load. In the independent new energy power supply system, in order to supply power to the load stably, continuously and reliably, researchers have proposed a variety of solutions, including: (1) equip the system with an energy storage device with a certain capacity to play an energy balance and support role, Supplement the short-term peak power of the system in time, recycle excess power, and improve the utilization rate of electric energy; (2) A variety of new energy sources are combined to supply power to the load, such as wind, light complementary power supply and light, heat complementary power supply, etc., using new energy power generation equipment The complementary characteristics between them supply power to the load, but the general new energy joint power supply system also needs to be equipped with a battery in order to supply power to the load more stably and reliably. In new energy power generation systems such as thermoelectric power generation and photovoltaic power generation systems, the output power of a single power generation device is very small. In order to increase the power generation of the system, a series-parallel combination of multiple power generation The output power is controlled by Maximum Power Point Tracking to maximize the power of the power generation equipment and increase the power generation, thereby improving the economic benefits of the system. However, due to the differences in the characteristics of each power generation device (such as each photovoltaic panel or thermoelectric power generation module) and the difference in its own environmental conditions, the characteristics of each power generation device are inconsistent, so it is difficult to ensure that each power generation device can output the maximum output by centralized control. In order to solve this problem, it is necessary to independently perform maximum power tracking control on each power generation device.

According to the above background requirements, in an independent new energy power supply system, it is necessary to manage and control the power of different power generation devices or multiple power generation devices, batteries and loads at the same time. In order to achieve system power control, usually multiple independent The individual converters control each device, battery and load power separately, resulting in a complex system, a large number of converters, a large volume and weight, and the power needs to be converted in multiple stages, which reduces the system efficiency. In order to solve the above problems, researchers proposed to use a multi-port converter to connect to the input source, battery and load at the same time, and realize the power management of each device in a unified and centralized way, which has the advantages of high system integration, high power density of the converter, and high system efficiency. advantage. Among the multi-port converters, there are many studies on three-port converters, and the technology is relatively mature, while there are fewer studies on multi-port converters containing more ports (such as four ports). The literature "Z. Qian, O .Abdel-Rahman, I.Batarseh.An integrated four-portDC/DC converter for renewable energy applications.IEEE Transactions on Power Electronics, 2010, vol.25, no.7, pp.1877-1887." Proposed a four-port The port converter is used for power management of the combined wind and light power supply system. The converter has a complex structure and the two input sources can only supply power to the load in a time-sharing manner, that is, the two input sources cannot supply power to the load at the same time.

Contents of the invention

1. Purpose of the invention: The present invention provides a novel four-port DC converter and its control method for the technical requirements in the background technology and the deficiencies of the prior art.

2. Technical solution: In order to achieve the above object, the present invention adopts the following technical solution: a four-port DC converter and its control method, characterized in that: the four-port DC converter includes a first input source (V _in1 ), The second input source (V _in2 ), the first diode (D ₁ ), the second diode (D ₂ ), the third diode (D ₃ ), the fourth diode (D ₄ ), the A capacitor (C ₁ ), a second capacitor (C ₂ ), a third capacitor (C ₃ ), a first switch tube (S ₁ ), a second switch tube (S ₂ ), a third switch tube (S ₃ ), The fourth switching tube (S ₄ ), battery (V _b ), transformer (T), output filter inductor (L _o ), output filter capacitor (C _o ) and load (R _o ), where the transformer (T) is composed of the original side winding ( _NP ), the first secondary winding ( _NS1 ) and the second secondary winding ( _NS2 ); the anode of the first input source (V _in1 ) is connected to the first diode (D ₁ ), the negative pole of the first input source (V _in1 ) is respectively connected to the positive pole of the second input source (V _in2 ), one end of the first capacitor (C ₁ ), one end of the second capacitor (C ₂ ), and the second The source of the switch tube (S ₂ ) and the drain of the fourth switch tube (S ₄ ), the cathode of the second input source (V _in2 ) is connected to the cathode of the second diode (D ₂ ), the first diode The cathode of the tube (D ₁ ) is respectively connected to the other end of the first capacitor (C ₁ ) and the drain of the first switching tube (S ₁ ), and the source of the first switching tube (S ₁ ) is respectively connected to the second switch The drain of the tube (S ₂ ) is connected to the terminal with the same name of the primary winding ( _NP ) of the transformer (T), and the non-identical terminal of the primary winding (V _P ) of the transformer (T) is respectively connected to the positive pole of the storage battery (V _b ) and One end of the third capacitor (C ₃ ), and the negative pole of the storage battery (V _b ) are respectively connected to the other end of the third capacitor (C ₃ ), the source of the fourth switching tube (S ₄ ) and the third switching tube (S ₃ ), the source of the third switching tube (S ₃ ) is respectively connected to the other end of the second capacitor (C ₂ ) and the anode of the second diode (D ₂ ), and the first secondary side of the transformer (T) The terminal with the same name of the winding ( _NS1 ) is connected to the anode of the third diode (D ₃ ), and the cathode of the third diode (D ₃ ) is respectively connected to the cathode of the fourth diode (D ₄ ) and the output filter One end of the inductor (L _o ) and the other end of the output filter inductor (L _o ) are respectively connected to one end of the output filter capacitor (C _o ) and one end of the load (R _o ), and the other end of the output filter capacitor (C _o ) is respectively Connected to the other end of the load (R _o ), the non-identical end of the first secondary winding ( _NS1 ) of the transformer (T) and the same-named end of the second secondary winding ( _NS2 ) of the transformer, the second secondary winding of the transformer (T) The non-identical end of the side winding ( _NS2 ) is connected to the fourth diode (D ₄ ) anode.

Further, the above-mentioned four-port DC converter and its control method are characterized in that: the switching frequency of the first, second, third and fourth switching tubes (S ₁ , S ₂ , S ₃ , S ₄ ) are equal, wherein the first switch tube (S ₁ ) and the second switch tube (S ₂ ) are turned on complementary, and the third switch tube (S ₃ ) and the fourth switch tube (S ₄ ) are turned on complementary.

Furthermore, the above-mentioned four-port DC converter and its control method are characterized in that: the first input source (V _in1 ) input power is realized by adjusting the duty cycle of the first switch tube (S ₁ ). Control of the input power of the second input source (V in2 ) is realized by adjusting the duty cycle of the third switching tube (S ₃ ), and the control of the input power of the second input source (V _in2 ) is realized by adjusting the first switching tube (S ₁ ) and the third switching tube (S ₃ ) The time interval between the two turn-on moments realizes the control of the voltage or current at both ends of the load (R _o ).

Features and technical effects of the present invention:

(1) The present invention can simultaneously realize the power management and control of two input sources, storage battery and load through one converter, and the conversion between the two input sources and the storage battery is non-isolated, and the conversion efficiency is relatively high;

(2) In the four-port DC converter of the present invention, the two input sources and the storage battery can supply power to the load independently, and can also supply power to the load at the same time, which can effectively ensure continuous, stable and reliable power supply to the load;

(3) The load is electrically isolated from the two input sources and the battery, which can adapt to the application requirements of different loads and applications;

(4) The four-port DC converter of the present invention uses the excitation inductance of the transformer as a filter inductance at the same time, and the number of switching devices used in the converter is small, the control method is simple, the reliability is high, and the cost is low.

Description of drawings

Fig. 1 is a circuit schematic diagram of a four-port DC converter of the present invention;

Fig. 2 is a waveform diagram of the working principle of the four-port DC converter of the present invention;

3 to 6 are equivalent circuit diagrams of the four-port DC converter of the present invention in working mode 1 to working mode 4 respectively;

Symbol names in Figures 1 to 6: V _in1 and V _in2 are the first and second input sources respectively; V _b is the storage battery; R _o is the load; T is the transformer; N _P is the primary winding of the transformer; N _S1 , N _S2 are the first and second secondary windings of the transformer respectively; S ₁ , S ₂ , S ₃ , S ₄ are the first, second, third and fourth switch tubes respectively; D ₁ , D ₂ , D ₃ , D ₄ is the first, second, third and fourth diodes; C ₁ , C ₂ , and C ₃ are the first, second and third capacitors; C _o is the filter capacitor; L _o is the filter inductance ; v _GS1 , v _GS2 , v _GS3 , v _GS4 are the driving voltages of the first, second, third and fourth switching tubes respectively; i _P is the primary winding current of the transformer; v _P is the primary winding voltage of the transformer; i _Lo is the filter inductor current.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing.

The schematic circuit diagram of the four-port DC converter of the present invention is shown in Figure 1. The four-port DC converter includes a first input source (V _in1 ), a second input source (V _in2 ), a first two-pole tube (D ₁ ), second diode (D ₂ ), third diode (D ₃ ), fourth diode (D ₄ ), first capacitor (C ₁ ), second capacitor (C ₂ ), the third capacitor (C ₃ ), the first switch tube (S ₁ ), the second switch tube (S ₂ ), the third switch tube (S ₃ ), the fourth switch tube (S ₄ ), the storage battery (V _b ), transformer (T), output filter inductor (L _o ), output filter capacitor (C _o ) and load (R _o ), where the transformer (T) consists of primary winding ( _NP ), first secondary winding ( _NS1 ) and the second secondary winding ( _NS2 ); the anode of the first input source (V _in1 ) is connected to the anode of the first diode (D ₁ ), and the anode of the first input source (V _in1 ) The negative electrode is respectively connected to the positive electrode of the second input source (V _in2 ), one end of the first capacitor (C ₁ ), one end of the second capacitor (C ₂ ), the source of the second switch tube (S ₂ ) and the fourth switch The drain of the tube (S ₄ ), the cathode of the second input source (V _in2 ) is connected to the cathode of the second diode (D ₂ ), and the cathode of the first diode (D ₁ ) is respectively connected to the first capacitor The other end of (C ₁ ) and the drain of the first switching tube (S ₁ ), the source of the first switching tube (S ₁ ) are respectively connected to the drain of the second switching tube (S ₂ ) and the transformer (T) The terminal with the same name of the primary winding ( _NP ), the non-identical terminal of the primary winding ( _NP ) of the transformer (T) are respectively connected to the positive pole of the battery (V _b ) and one end of the third capacitor (C ₃ ), and the battery (V The negative electrode of _b ) is respectively connected to the other end of the third capacitor (C ₃ ), the source of the fourth switch (S ₄ ) and the drain of the third switch (S ₃ ), and the third switch (S ₃ ) The source of the transformer (T) is connected to the other end of the second capacitor (C ₂ ) and the anode of the second diode (D ₂ ), and the same-named end of the first secondary winding ( _NS1 ) of the transformer (T) is connected to the third and second The anode of the diode (D ₃ ), the cathode of the third diode (D ₃ ) are respectively connected to the cathode of the fourth diode (D ₄ ) and one end of the output filter inductor (L _o ), the output filter inductor (L _o ) The other end is respectively connected to one end of the output filter capacitor (C _o ) and one end of the load (R _o ), and the other end of the output filter capacitor (C _o ) is respectively connected to the other end of the load (R _o ), the transformer ( T) The non-identical end of the first secondary winding ( _NS1 ) and the identical end of the second secondary winding ( _NS2 ) of the transformer, and the non-identical end of the second secondary winding ( _NS2 ) of the transformer (T) is connected to the second Anode of quad diode (D ₄ ).

The control method of the four-port DC converter of the present invention is as follows: the switching frequencies of the first, second, third and fourth switch tubes (S ₁ , S ₂ , S ₃ , S ₄ ) are equal, and the first switch tube (S ₁ ) and the second switching tube (S ₂ ) are turned on complementary, and the third switching tube (S ₃ ) and the fourth switching tube (S ₄ ) are turned on complementary; by adjusting the first switching tube (S ₁ ) The duty ratio of the first input source (V _in1 ) is realized to control the input power of the first input source (V in1 ), and the control of the input power of the second input source (V _in2 ) is realized by adjusting the duty ratio of the third switching tube (S ₃ ). The time interval between the turn-on moments of the first switch tube (S ₁ ) and the third switch tube (S ₃ ) realizes the control of the voltage or current at both ends of the load (R _o ).

In one embodiment of the present invention: the voltages of the first and second input sources both vary between 25-35V, the power of the two input sources varies between 0-100W, the battery voltage is 24V, and the load terminal voltage is 30V, load power 150W, the first to fourth switching tubes S ₁ -S ₄ are all made of MOSFETs, and the switching frequency is 100kHz.

The specific working principle of the converter is described below.

The converter needs to control the power of the first and second input sources, the battery and the load at the same time, assuming that the turns ratio of the primary and secondary windings of the transformer satisfies N _P : N _S1 : N _S2 = 1: n: n, n is a positive number, At the same time, it is assumed that the filter capacitor C _o is large enough, the output voltage is a smooth DC, the transformer excitation inductance is L _m , the transformer excitation inductance current is i _Lm , and the voltage of the load R _o is V _o .

The converter has four possible working modes in one switching cycle. The principle waveform of the converter is shown in Figure 2, and the equivalent circuits of the converter in different working modes are shown in Figures 3 to 6 respectively. .

Working mode 1[t ₀ ～t ₁ ]: Before time t ₀ , S ₂ and S ₃ are turned on together, S ₁ and S ₄ are turned off, the output filter inductor current i _Lo decreases linearly, and the transformer excitation inductor current i _Lm Linear increase; at time t ₀ , S ₁ is turned on, S ₂ is turned off, and the equivalent circuit is shown in Figure 3. In this mode, the transformer primary winding current i _P , the exciting inductor current i _Lm and the filter inductor current i _Lo satisfy the following relationship:

$\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; L\; m</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

$\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; Lo</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

$\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; L\; m</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; Lo</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

Mode 2 [t ₀ ~ t ₂ ]: At time t ₁ , S ₃ is turned off, S ₄ is turned on, and the equivalent circuit is shown in Figure 4. In this mode, the transformer primary winding current i _P , the exciting inductor current i _Lm and the filter inductor current i _Lo satisfy the following relationship:

$\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; L\; m</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}{\mathrm{<span\; class="notranslate">\; L\; m</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

$\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; Lo</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

$\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; L\; m</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; Lo</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

Mode 3 [t ₂ ～t ₃ ]: At time t ₂ , S ₁ is turned off and S ₂ is turned on. The equivalent circuit is shown in Fig. 5 . In this mode, the transformer primary winding current i _P , the exciting inductor current i _Lm and the filter inductor current i _Lo satisfy the following relationship:

$\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; L\; m</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}{\mathrm{<span\; class="notranslate">\; L\; m</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

$\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; Lo</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; no</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

$\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; L\; m</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; Lo</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 9</span>}<span\; class="notranslate">\; )</span>$

Mode 4 [t ₃ ～t ₄ ]: At time t ₃ , S ₄ is turned off and S ₃ is turned on. The equivalent circuit is shown in Figure 6. In this mode, the transformer primary winding current i _P , the exciting inductor current i _Lm and the filter inductor current i _Lo satisfy the following relationship:

$\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; L\; m</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}{\mathrm{<span\; class="notranslate">\; L\; m</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; )</span>$

$\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; Lo</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; in</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 11</span>}<span\; class="notranslate">\; )</span>$

$\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; L\; m</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; di</span>}}_{\mathrm{<span\; class="notranslate">\; Lo</span>}}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 12</span>}<span\; class="notranslate">\; )</span>$

Assuming that the switching period is T _s , the duty ratios of S ₁ and S ₃ are d ₁ and d ₃ respectively and the time interval between the time when S ₁ is turned on and the time when S ₃ is turned on is ΔT, then ΔT=t ₄ -t ₃ , Order: d ₀ =ΔT/T _s , when the converter works in a steady state, according to the volt-second balance relationship between the transformer excitation inductance and the output filter inductance:

V _b ＝d ₁ ·V _in1 +d ₃ V _in2 (13)

V _o =2n(1-d ₁ -d ₀ )V _b (14)

Since the output powers of the first and second input sources are respectively proportional to the duty ratios of S1 _{and S3} , the input power of the two input sources can be adjusted by adjusting the duty ratios of _S1 and _S3 , according to the formula ( 14) It can be seen that the load voltage can be further controlled by adjusting the time interval between the turn-on moments of _S1 and _S3 . Therefore, the four-port DC converter of the present invention can simultaneously realize the power management of two input sources, batteries and loads and control.

Claims (3)

1. port DC converter and control method thereof, it is characterized in that: described four port DC converter comprise the first input source (V _In1), the second input source (V _In2), the first diode (D ₁), the second diode (D ₂), the 3rd diode (D ₃), the 4th diode (D ₄), the first electric capacity (C ₁), the second electric capacity (C ₂), the 3rd electric capacity (C ₃), the first switching tube (S ₁), second switch pipe (S ₂), the 3rd switching tube (S ₃), the 4th switching tube (S ₄), storage battery (V _b), transformer (T), output inductor (L _o), output filter capacitor (C _o) and load (R _o), wherein, transformer (T) is by former limit winding (N _P), the first secondary winding (N _S1) and the second secondary winding (N _S2) constitute;

The described first input source (V _In1) positive pole be connected in the first diode (D ₁) anode, the first input source (V _In1) negative pole be connected in the second input source (V respectively _In2) positive pole, the first electric capacity (C ₁) an end, the second electric capacity (C ₂) an end, second switch pipe (S ₂) source electrode and the 4th switching tube (S ₄) drain electrode, the second input source (V _In2) negative pole be connected in the second diode (D ₂) negative electrode, the first diode (D ₁) negative electrode be connected in the first electric capacity (C respectively ₁) the other end and the first switching tube (S ₁) drain electrode, the first switching tube (S ₁) source electrode be connected in second switch pipe (S respectively ₂) drain electrode and transformer (T) former limit winding (N _P) end of the same name, transformer (T) former limit winding (N _P) non-same polarity be connected in storage battery (V respectively _b) positive pole and the 3rd electric capacity (C ₃) an end, storage battery (V _b) negative pole be connected in the 3rd electric capacity (C respectively ₃) the other end, the 4th switching tube (S ₄) source electrode and the 3rd switching tube (S ₃) drain electrode, the 3rd switching tube (S ₃) source electrode be connected in the second electric capacity (C respectively ₂) the other end and the second diode (D ₂) anode, transformer (T) the first secondary winding (N _S1) end of the same name be connected in the 3rd diode (D ₃) anode, the 3rd diode (D ₃) negative electrode be connected in the 4th diode (D respectively ₄) negative electrode and output inductor (L _o) an end, output inductor (L _o) the other end be connected in output filter capacitor (C respectively _o) an end and load (R _o) an end, output filter capacitor (C _o) the other end be connected in load (R respectively _o) the other end, transformer (T) the first secondary winding (N _S1) non-same polarity and the transformer second secondary winding (N _S2) end of the same name, transformer (T) the second secondary winding (N _S2) non-same polarity be connected in the 4th diode (D ₄) anode.

2. a kind of four port DC converter and control methods thereof according to claim 1, it is characterized in that: the first, second, third and the 4th switching tube (S1, S2, S3, S4) switching frequency equates, wherein first switching tube (S1) and the complementary conducting of second switch pipe (S2), the 3rd switching tube (S3) and the complementary conducting of the 4th switching tube (S4).

3. a kind of four port DC converter and control methods thereof according to claim 1, it is characterized in that: realize the control of first input source (Vin1) input power by the duty ratio of regulating described first switching tube (S1), realize the control of second input source (Vin2) input power by the duty ratio of regulating described the 3rd switching tube (S3), realize the control of load (Ro) both end voltage or electric current by regulating both time intervals between opening constantly of first switching tube (S1) and the 3rd switching tube (S3).

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