TW201436437A - High-efficiency bidirectional single-input and multi-outputs DC/DC converter - Google Patents

Abstract

A high-efficiency bidirectional single-input and multi outputs DC/DC converter is provided in the present invention. In the high-efficiency bidirectional single-input and multi-outputs DC/DC converter, a coupled inductor is adopted for increasing the voltage ratio between the input voltage and output voltage. In addition, an auxiliary power supply circuit with an auxiliary inductor coupled to the low-voltage switch and clamping circuit is provided. The design of the converter uses the characteristic of continuous current of the leakage inductor of the coupled inductor, such that the soft-switching property can be achieved. Therefore, the switching loss is reduced. Also, the issue of the reverse recovery current within the diode is solved. Further, the variation of the output voltage of the auxiliary power supply circuit can be designed at a preset range from light load to heavy load.

Description

High efficiency reversible single input multi output DC converter

The present invention relates to a power electronics technology, and more particularly to a two-way energy transfer, single input multiple output, high efficiency, high boost ratio reversible single input multiple output DC converter.

Figure 1 is a circuit diagram of a prior art boost converter. Please refer to Figure 1 to increase the level of the input voltage by adjusting the duty cycle of the switch. When the power semiconductor switch of the prior art boost converter is turned off, the voltage across the two ends is the voltage value on the output side, so it is necessary to select a power semiconductor switch with a withstand voltage greater than or equal to the output side voltage, if a metal field is used. The effect transistor element (MOSFET element), whose characteristics contain a large on-resistance (R _DS(ON) ), naturally leads to a higher conduction loss. In addition, in the conventional boost converter, the diode at the output has a problem of reverse-recovery. When the power semiconductor switch is turned on, the output diode must establish a reverse bias voltage almost with the surge current. This current flows through the power semiconductor switch, which will cause severe switching loss, so that its conversion efficiency is not good. However, due to its simple structure and low cost, it is widely used in the industry in the case of low boost ratio and undemanding efficiency, such as Power Factor Correction (PFC).

At present, the second conventional boosting architecture utilizes a transformer, and the greatest advantage of this circuit is to isolate the high and low voltage side circuits. Generally, the DC/DC converter of the transformer is used most often, but the buck converter is used. The advantage is that the component with low conduction loss is used on the low voltage side, and when the high voltage side switch is turned off, the leakage current is not directly transmitted to the switch. On the low voltage side, the components of the low-voltage side circuit are broken due to excessive voltage. However, the balance control of the excitation current and the leakage energy treatment are all problems to be overcome. In addition, there are many disadvantages when the transformer is applied to the boosting structure. For example, the highest voltage gain is equal to the turns ratio, and the output rectifying diode is subjected to at least twice the stress of the output voltage, so that the cushioning circuit is an indispensable device.

What is the meaning of isolation for the boost circuit? If the circuit's active power is on the low-voltage side, in other words, the control circuit can control the system voltage, and the controlled open-circuit relationship uses the voltage-clamping technology to use the lower-voltage rated power semiconductor switch. Is there still isolation? So all circles have researched and developed non-isolated boost architectures. FIG. 2 is a circuit diagram of a prior art coupled inductive booster circuit. As shown in Figure 2, it also has a Flyback high boost ratio feature. Since the coupled inductor is a non-isolated boost architecture, the primary side circuit can assist boost, and the boost ratio and output power are superior to the flyback circuit. However, in the circuit of Fig. 2, when the switch is turned off, the surge voltage generated by the leakage inductance must be added with a cushioning circuit. It consumes its energy and avoids damage caused by over-voltage of the switch, so its conversion efficiency is not good.

Therefore, many experts and scholars have proposed high-efficiency boost converter technology (such as the papers listed in the following notes) to improve the shortcomings of the above-mentioned conventional boost converters, which are roughly divided into four categories: Reference [1] Using the leakage inductance of the coupled inductor and the switching parasitic capacitance. (Generally known as output capacitor) (Parasitic Capacitance or Output Capacitance) resonant characteristics, the switch is turned on at the lowest point of the resonant voltage, to solve the problem of reverse recovery current of the diode, so the switching loss is greatly reduced, and is a single switch architecture, light The load efficiency can reach over 97%. References [1] many shortcomings: (1) the switch still has to withstand the voltage and current of the high and low voltage side; (2) the switch capacity utilization is low, with TO-247 switch packaging capacity, but only 200W output, obviously the architecture The high efficiency characteristics can not be expressed under higher load; (3) the inductor current ripple and the switching loss are higher; (4) only increase the input voltage by 50%, the boost ratio is low; (5) the inverter control will The flexible switching effect of the drive circuit is complicated and heavy load is limited. Generally, the resonant circuit is susceptible to changes in load and inductance and capacitance parameters, and the switching current is chopped, which will increase the additional conduction loss. Reference [2] output power up to 1.6kW conversion efficiency is higher than the above literature, however, this circuit needs to be equipped with an auxiliary switch, the control circuit is more complicated. The voltage difference between the output 400V and the input 300V is not high, and the conduction current is low, so flexible switching will be the key technology to achieve high efficiency conversion. Generally speaking, as long as the problem of reverse recovery current of the diode is effectively dealt with, the non-isolated architecture converter with high input voltage and low boost ratio has a short switch-on time, which means that only the differential pressure energy between the output terminal and the input terminal is With the switch provided, the relative switch conduction loss is small, and in theory, the conversion efficiency can be greatly improved. Basically, the most important part of flexible switching is the loss of the short-circuit current of the parasitic capacitance of the switch when the switch is turned on. If the reverse recovery current portion of the diode is not considered, most of the switching loss of the switching transistor is equal to 0.5 × f _s × C _oss × V ² _DS [1], where f _s is the switching frequency, V _DS is the switching voltage, and C _oss is the switching parasitic capacitance. If the voltage at both ends is lower than 50V before the switch is turned on, the switching loss will greatly decrease in the proportion of total loss. Therefore, operating in this voltage range with flexible switching characteristics has limited benefits for improving conversion efficiency.

References [3] using transformers with flexible switching technology, the highest efficiency can reach 97.5%, but the boost ratio is less than three times, and much lower than the turns ratio. The voltage applied to the switch is the same as the output voltage. Therefore, the transformer does not fully utilize the low voltage characteristics after isolation to apply to the low-power side low-conductance power semiconductor switch.

Reference [4] has successfully dealt with the problem of leakage inductance energy, and at the same time achieved the effect of switching voltage clamping. In this paper, the clamp capacitor absorbs the low-current leakage inductance instantaneous large current, which also helps to increase the voltage gain. On the other hand, in the clamp mode, the voltage applied by the switch is lower than the output voltage, and the boost ratio is the highest among the above-mentioned structures, which shows good conversion efficiency and high efficiency even at the rated power output. The high boost ratio converter takes a big step. Subsequent published reference [5] describes the reference [4] architecture when the switch is turned on, the high-voltage side diode must withstand the reverse bias of V _O + nV _IN (V _O and V _IN are the output voltage, n is the number of turns In contrast, the surge voltage must be used in conjunction with the snubber circuit to eliminate the leakage voltage caused by the leakage inductance. This situation is more obvious in the high output voltage and high turns ratio architecture. Reference [5] adjusts the output capacitance of the former to the secondary high-voltage circuit, effectively reducing the reverse bias of the diode, but it is undeniable that the cushioning circuit cannot be discarded.

Reference [6] utilizes a two-stage or single-stage architecture, flexible switching plus transformer boosting to achieve high voltage gain. After the secondary side of the transformer is rectified, multiple sets of windings are connected in series to obtain a high voltage output of 3.2 kV, which is mainly used for power supply for communication satellites. Similar circuit connection is also found in reference [5]. Due to the flexible switching characteristics, the problem of reverse recovery current of the high-voltage side diode is effectively dealt with, so the conversion efficiency is very high, the input voltage is 26V-44V, and the minimum efficiency is 94.1% when the rated 150W load is supplied. In terms of it, it is a classic. Further analysis, in fact, 3.2kV is the secondary side multi-winding voltage series connection can be raised to this range, if the maximum output voltage of a single winding is only 750V. The main architecture uses four switches, three inductors and one transformer. The maximum voltage of the auxiliary switch is 150V. The actual voltage is 250V-23A. The maximum voltage of the main switch is 120V. The voltage is 200V-100A. All four TO-247 switches are used, but the output power is only 150W, and the capacity of the components is not fully utilized. However, the architecture is used for communication satellites, and efficiency is the primary consideration.

A comprehensive review of the references listed in the prior art and other coupled inductor architectures, the voltage waveforms across the switch, as in Figure 15 of Reference [1] (Fig. 15) and Figure 19 of Reference [5] (Fig. .19) The voltage waveform of the measured switch transistor has a surge voltage at the cut-off instant. If the voltage exceeds half of the normal span voltage, the switch voltage specification must be increased or even higher than the output voltage. With the manufacturing characteristics of power metal-based semiconductor field-effect transistors (POWER MOSFETs), the ratio of R _DS(ON) increase will be much higher than the voltage rise. Generally, the conduction loss of metal-semiconductor field-effect transistors is proportional to the square of the current. The high-voltage power metal-semiconductor field-effect transistor's heavy-duty conduction loss will be higher than that of the IGBT power semiconductor switch. Therefore, some high-efficiency circuits can only behave at light load. This is the general researcher's long-term avoidance. At the office. The switching surge voltage presented in reference [1] and reference [5] is caused by the instantaneous current change caused by the current flowing through the inductance of the line and the component when the coupling inductor is turned off at the primary side. The solution must be a parallel snubber circuit on both sides of the switch. The flow path must be as short as possible. This path must have both a low skin effect and a mutual inductance value, so that a lower voltage low conduction loss switch can be effectively used, so high efficiency. With high boost ratio devices, voltage clamping technology is far more important than flexible switching mechanisms.

I would like to summarize the previous high boost ratio converter technology: (1) the resonant circuit should be used in the high input voltage architecture; (2) the switching capacity is not fully utilized; (3) can not be on the high and low side simultaneously All components achieve voltage clamping; (4) failure to fully utilize the characteristics of the excitation current and induced current of the transformer; (5) the conversion efficiency cannot be fully improved; (6) the salty structure can achieve high efficiency and high boost ratio at the same time. (7) Complex architecture or control. This application overcomes the above-mentioned disadvantages and overcomes the goal of achieving a high-efficiency high-boost ratio conversion device one by one. Under the premise that the same turns ratio and duty cycle are on, the voltage gain ratio is higher than the foregoing structure. In addition, the present application additionally adds a step-down circuit to form a reverse power conversion loop to provide the need for two-way energy transfer of an increasingly energy storage component. In addition to this In addition, the present application additionally adds at least one auxiliary power supply circuit, in addition to pushing an additional load, the circuit architecture can also achieve the purpose of flexible switching.

references

1. DC Lu, DKW Cheng, and YS Lee, "A single-switch continuous-conduction-mode boost converter with reduced reverse-recovery and switching losses," IEEE Transactions on Industrial Electronics, vol. 50, pp. 767-776, 2003.

2. C. M. C. Duarte, and I. Barbi, “An improved family of ZVS-PWM active-clamping DC-to-DC converters,” IEEE Transactions on Power Electronics, vol. 17, pp. 1-7, 2002.

3. ES da Silva, L. dos Reis Barbosa, JB Vieira, Jr., LC de Freitas, and VJ Farias, “An improved boost PWM soft-single-switched converter with low voltage and current stresses,” IEEE Transactions on Industrial Electronics , vol. 48, pp. 1174-1179, 2001.

4. Q. Zhao, and F. C. Lee, “High-efficiency, high step-up DC-DC converters,” IEEE Transactions on Power Electronics, vol. 18, pp. 65-73, 2003.

5. K. C. Tseng, and T. J. Liang, “Novel high-efficiency step-up converter,” IEE Proceedings Electric Power Applications, vol. 151, pp. 182-190, 2004.

6. I. Barbi, and R. Gules, "Isolated DC-DC converters with high-output voltage for TWTA telecommunication satellite applications," IEEE Transactions on Power Electronics, vol. 18, pp. 975-984, 2003.

It is an object of the present invention to provide a reversible single-input multi-output DC converter, thereby providing a DC converter having a simple architecture, single-input multiple-output, flexible switching, power supply stability, high-voltage differential ratio, and bidirectional energy transfer.

In view of this, the present invention provides a high efficiency reversible single input multiple output DC converter including a low voltage power supply load, a high voltage power supply load, a coupled inductor, and a low voltage circuit. , a medium voltage circuit, a high voltage circuit, a step-down circuit, a control circuit and a first auxiliary power circuit. The low voltage power supply load includes a low voltage power supply input and output terminal and a common voltage terminal. The high voltage power supply load includes a high voltage power supply input and output terminal and the above common voltage terminal. The coupled inductor includes a primary side winding and a secondary side winding. The low voltage circuit includes a first filter capacitor, a low voltage switch, and a primary side winding of the coupled inductor.

The first filter capacitor includes a first end and a second end, wherein the first end of the first filter capacitor is coupled to the low voltage power load The input end of the low voltage power supply, the second end of the first filter capacitor is coupled to the common voltage end of the low voltage power load. The low voltage switch includes a first end and a second end, wherein the second end of the low voltage switch is coupled to the common voltage end of the low voltage power load. The primary winding of the coupled inductor includes a first end and a second end, wherein the first end of the primary winding of the coupled inductor is coupled to the low voltage power input and output of the low voltage power supply, and the second end of the primary winding of the coupled inductor The first end of the low voltage switch is coupled.

The medium voltage circuit includes a secondary side winding of the coupled inductor and a medium voltage capacitor. The secondary winding of the coupled inductor includes a first end and a second end, wherein the first end of the secondary winding of the coupled inductor is coupled to the first end of the low voltage switch. The medium voltage capacitor includes a first end and a second end, wherein the first end of the medium voltage capacitor is coupled to the second end of the secondary winding of the coupled inductor. The high voltage circuit includes a second filter capacitor and a high voltage switch. The second filter capacitor includes a first end and a second end, wherein the first end of the second filter capacitor is coupled to the high voltage power input and output end of the high voltage power supply load, and the second end of the second filter capacitor is coupled to the high voltage power load Connected to the voltage terminal. The high voltage switch includes a first end and a second end, wherein the first end of the high voltage switch is coupled to the second end of the medium voltage capacitor, and the second end of the high voltage switch is coupled to the high voltage power input end of the high voltage power load .

The buck circuit includes a buck switch, a buck diode, and a buck inductor. The buck switch includes a first end and a second end, wherein the first end of the buck switch is coupled to the second end of the medium voltage capacitor. The step-down diode includes an anode and a cathode, wherein the anode of the step-down diode is coupled to the common voltage terminal of the high voltage power supply load, and the cathode of the step-down diode The second end of the buck switch is coupled. The buck inductor includes a first end and a second end, wherein the first end of the buck inductor is coupled to the second end of the buck switch, and the second end of the buck inductor is coupled to the low voltage power output of the low voltage power load Into the end.

The first auxiliary power supply circuit is coupled to the low voltage circuit, wherein the first auxiliary power supply circuit has a first auxiliary inductance. The control circuit is used to control the on and off of the low voltage switch, the high voltage switch, and the buck switch. In a low voltage to high voltage mode, the control circuit controls the low voltage switch and the high voltage switch according to the state of the high voltage power supply load, and the control circuit keeps the buck switch off. When the low voltage switch is turned on, the primary side winding stores energy in a first magnetizing inductance. When the low voltage switch is turned off, the primary side winding releases the energy stored in the first magnetizing inductance. The secondary side winding generates a potential difference through mutual inductance with the primary side winding. When the low voltage switch is turned on, the secondary side winding stores the potential difference to the medium voltage capacitor. When the low voltage switch is turned off, the secondary side winding continues to flow the above potential difference to the medium voltage. capacitance. The high voltage switch receives the energy in the medium voltage capacitor, thereby outputting a second output voltage to the high voltage power supply load. When the low voltage switch is turned off, the first auxiliary inductance of the first auxiliary power supply circuit stores the energy released by the primary side winding, and outputs an auxiliary voltage according to the energy released by the primary side winding and the first auxiliary inductance.

In the high voltage to low voltage mode, the control circuit controls the low voltage switch, the high voltage switch and the buck switch according to the state of the low voltage power load, wherein the on time of the low voltage switch and the buck switch are in phase, and the on time of the low voltage switch and the high voltage switch Is the opposite phase. When the high voltage switch is turned on, the secondary winding stores energy in a second magnetizing inductance, the primary winding The energy stored in the second magnetizing inductance is released. The primary side winding generates a potential difference through mutual inductance with the secondary side winding. When the low voltage switch is turned on, the secondary side winding stores a potential difference. When the low voltage switch is turned on, the primary side winding has a freewheeling potential difference to the low voltage power supply load. When the buck switch is turned on, the energy stored in the medium voltage capacitor is continuously discharged to the low voltage power supply through the buck inductor; when the buck switch is turned off, the buck inductor is used to flow the energy to the low voltage power supply through the buck diode. load. When the low voltage switch is turned off, the first auxiliary inductor of the first auxiliary power supply circuit stores the energy released by the secondary side winding, and outputs the auxiliary voltage according to the energy released by the secondary side winding and the first auxiliary inductor. Regardless of the low voltage to high voltage mode or the high voltage to low voltage mode, the first auxiliary power supply circuit is configured to provide an auxiliary voltage for driving the power coupled to the load of the first auxiliary power supply circuit.

According to a high efficiency reversible single-input multiple-output DC converter according to a preferred embodiment of the present invention, the clamp circuit includes a first clamp diode, a clamp capacitor, and a second clamp diode. The first clamping diode includes an anode and a cathode, wherein an anode of the first clamping diode is coupled to the first end of the low voltage switch. The clamp capacitor includes a first end and a second end, wherein the first end of the clamp capacitor is coupled to the cathode of the first clamp diode, and the second end of the clamp capacitor is coupled to the common voltage end of the low voltage power load . The second clamp diode includes an anode and a cathode, wherein the anode of the second clamp diode is coupled to the first end of the clamp capacitor, and the cathode of the second clamp diode is coupled to the capacitor of the medium voltage capacitor Two ends.

A high efficiency reversible single input multiple output DC converter according to a preferred embodiment of the present invention, the first auxiliary power supply circuit The first auxiliary inductor, a first auxiliary diode, a first auxiliary filter capacitor, and a first auxiliary power supply load are included. The first auxiliary inductor includes a first end and a second end, wherein the first end of the first auxiliary inductor is coupled to the first end of the low voltage switch. The first auxiliary diode includes an anode and a cathode, wherein an anode of the first auxiliary diode is coupled to the second end of the first auxiliary inductor. The first auxiliary filter capacitor includes a first end and a second end, wherein the first end of the first auxiliary filter capacitor is coupled to the cathode of the first auxiliary diode, and the second end of the first auxiliary filter capacitor is coupled The common voltage terminal of the low voltage power supply load. The first auxiliary power supply load includes a first end and a second end, wherein the first end of the first auxiliary power load is coupled to the cathode of the first auxiliary diode, and the second end of the first auxiliary power load is coupled The common voltage terminal of the low voltage power supply load.

According to the high efficiency reversible single-input multi-output DC converter according to the preferred embodiment of the present invention, the first auxiliary power supply circuit can assist zero voltage and zero current switching to increase circuit conversion efficiency and reduce switching loss. In another embodiment, the effect of the first auxiliary power supply circuit to achieve more sets of voltage outputs may be additionally added.

The spirit of the present invention is to design a coupled inductor in the high efficiency reversible single-input multi-output DC converter, and to increase the boost ratio by using the coupled inductor. In addition, at least one auxiliary power source having an auxiliary inductance is additionally added to the coupling of the clamp circuit and the low voltage switch. The high-efficiency reversible single-input multi-output DC converter uses the characteristic of continuous leakage of the leakage inductance current of the coupled inductor to achieve a flexible switching effect of the switch, thereby reducing switching loss. And, the input of this DC converter The diode has no reverse recovery current problem and improves the power conversion efficiency. In addition, the output voltage of the auxiliary power supply to the load can be designed within a predetermined range, so that the auxiliary power load can be applied from light load to heavy load.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

S ₁ ‧‧‧ low voltage switch

C _FC ‧‧‧first filter capacitor

T _r ‧‧‧coupled inductor

L _p ‧‧‧ primary winding of coupled inductor T _r

Secondary winding L _s ‧‧‧ of coupled inductor T _r

C ₂ ‧‧‧ medium voltage capacitor

C ₁ ‧‧‧Clamping capacitor

D ₁ ‧‧‧First clamped diode

D ₃ ‧‧‧Second clamped diode

S ₃ ‧‧‧High voltage switch

C _bus ‧‧‧second filter capacitor

S ₂ ‧‧‧Buck Switch

L ₂ ‧‧‧Buck Inductance

D ₂ ‧‧‧Bucking diode

L _aux ‧‧‧First auxiliary inductor

C ₃ ‧‧‧First auxiliary filter capacitor

D ₄ ‧‧‧First auxiliary diode

R _{O 3} ‧‧‧First auxiliary power equivalent load

300‧‧‧Low-voltage power supply load

301‧‧‧High voltage power supply load

302‧‧‧Low voltage circuit

303‧‧‧ medium voltage circuit

304‧‧‧Clamping circuit

305‧‧‧High voltage circuit

306‧‧‧Buck circuit

307‧‧‧First auxiliary power supply circuit

308‧‧‧Control circuit

L _{aux 2} ‧‧‧Second auxiliary inductor

D ₅ ‧‧‧Second auxiliary diode

C ₄ ‧‧‧Second auxiliary filter capacitor

R _{O 4} ‧‧‧Second auxiliary power supply load

Figure 1 is a circuit diagram of a prior art boost converter.

FIG. 2 is a circuit diagram of a prior art coupled inductive booster circuit.

FIG. 3 is a circuit diagram of a high efficiency reversible single input multiple output DC power converter according to an embodiment of the present invention.

FIG. 4(a) is a diagram showing an equivalent circuit diagram of the reversible single-input multi-output DC converter operating in a high-voltage to low-voltage mode according to an embodiment of the present invention.

FIG. 4(b) is an equivalent circuit diagram of the reversible single-input multi-output DC converter operating in the low-voltage to high-voltage mode according to an embodiment of the present invention.

FIG. 5 is a diagram showing voltage and current timing waveforms of a reversible single-input multi-output DC converter operating in a high-voltage to low-voltage mode according to an embodiment of the invention.

Figure 6 is a diagram showing a reversible type according to an embodiment of the present invention. The single-input multi-output DC converter operates in a circuit operation mode analysis diagram of the high-voltage to low-voltage mode.

FIG. 7 is a diagram showing voltage and current timing waveforms of a reversible single-input multi-output DC converter operating in a low-voltage to high-voltage mode according to an embodiment of the invention.

FIG. 8 is a diagram showing the circuit operation mode analysis of the reversible single-input multi-output DC converter operating in the low-voltage to high-voltage mode according to an embodiment of the invention.

FIG. 9 is a circuit diagram of a high efficiency reversible single input multiple output DC power converter according to another embodiment of the present invention.

FIG. 10 is a diagram showing conversion efficiency of a high efficiency reversible single input multi-output DC converter according to an embodiment of the present invention.

FIG. 3 is a schematic structural diagram of a high efficiency reversible single input multiple output DC power converter according to an embodiment of the invention. Referring to FIG. 3, the structure of the reversible single-input multi-output DC power converter comprises a low-voltage power supply load 300, a high-voltage power supply load 301, a low-voltage circuit 302, a medium-voltage circuit 303, a clamp circuit 304, and a high voltage. The circuit 305, a step-down circuit 306, a first auxiliary power circuit 307 and a control circuit 308. This high efficiency reversible single-input multi-output DC power converter is interchangeable and can generate multiple sets of output voltages at the same time. In other words, if the input power is at the high voltage power supply load 301, the output load is the low voltage power supply load 300, and if the input power supply is at the low voltage power supply load 300, the input is lost. The output load is a high voltage power supply load 301, and the first auxiliary power supply circuit 307 generates a corresponding voltage to supply the load to which it is coupled 307.

Low-voltage circuit consists of a low-voltage switches S _1, a first filter capacitor C _FC, the primary winding coupled inductor L _P T _r of the composition. The secondary side winding L _S of the medium-voltage routing coupling inductor T _r is composed of a medium voltage capacitor C ₂ , which is interposed between the low voltage circuit and the high voltage circuit. The clamping circuit is composed of a clamping capacitor C ₁ , a first clamping diode D ₁ and a second clamping diode D ₃ . The high voltage _{circuit is} composed of a high voltage switch S ₃ and a second filter capacitor C _bus . The step-down circuit is composed of a step-down switch S ₂ , a step-down inductor L ₂ and a step-down diode D ₂ . The first auxiliary power supply circuit is composed of a first auxiliary inductor L _aux , a first auxiliary filter capacitor C ₃ , a first auxiliary diode D ₄ and a first auxiliary power equivalent load R _{O 3} . The control circuit 308 is configured to control the on and off of the low voltage switch S ₁ , the high voltage switch S _{3 ,} and the buck switch S ₂ according to the control mode and the load state. The coupling relationship of the above high efficiency reversible single-input multi-output DC power converter is as shown in the figure.

The high-efficiency reversible single-input multi-output DC power converter includes two working modes, one is a low-voltage to high-voltage mode, and is supplied by a low-voltage power supply load 300 to a high-voltage power supply load 301; the second is a high-voltage to low-voltage mode, and the high-voltage power supply load 301 Power is supplied to the low voltage power supply load 300. Regardless of whether the high efficiency reversible single-input multi-output DC power converter operates in a low-voltage to high-voltage mode or a high-voltage-to-low-voltage mode, the first auxiliary power supply circuit 307 can provide the auxiliary voltage to drive the first auxiliary power supply circuit. 307 load R _O3 power.

In the low voltage to high voltage mode, the control circuit 308 controls the low voltage switch S ₁ and the high voltage switch S ₃ according to the state of the high voltage power supply load 301, and the control circuit 308 keeps the step down switch S ₂ in an off state, and therefore, the step down circuit 306 is in The state of not working. When the low-voltage switch S _{1 is} turned on, the primary side winding L _{P of the} coupled inductor T _r stores energy in a first magnetizing inductance. When the low-voltage switch S ₁ is turned off, the primary side winding L _{P of the} coupled inductor T _r is released and stored in the first. The energy stored in a magnetizing inductance. The secondary side winding L _{S of the} coupled inductor T _r transmits a potential difference through the mutual inductance with the primary side winding L _P . When the low voltage switch S _{1 is} turned on, the secondary side winding L _{S of the} coupled inductor T _r stores the above potential difference in the medium voltage Capacitor C ₂ , when the low voltage switch is turned off, the secondary side winding continues to flow the above potential difference to the medium voltage capacitor C ₂ . Thereafter, the high voltage switch S ₃ receives the energy in the medium voltage capacitor C ₂ and supplies the second output voltage V _bus to the high voltage power supply load 301. Further, in the low pressure switch S ₁ is turned off, the first auxiliary power supply circuit 307 of a first auxiliary inductor L _aux stored energy of the primary winding L _P released, and according to the primary winding and a first auxiliary inductor L _P L _aux release The energy output is an auxiliary voltage V _{O 3} .

In the high voltage to low voltage mode, the control circuit 308 controls the low voltage switch S ₁ , the high voltage switch S ₃ and the buck switch S ₂ according to the state of the low voltage power supply load 300, wherein the on time of the low voltage switch S ₁ and the buck switch S ₂ is In phase, and the on-time of the low-voltage switch S ₁ and the high-voltage switch S ₃ is reversed. When the high voltage switch S _{3 is} turned on, the secondary side winding L _{S of the} coupled inductor T _r stores energy in the second magnetizing inductance, and the energy stored in the second magnetizing inductance is released by the primary side winding L _P . The primary side winding L _P transmits a potential difference through the mutual inductance with the secondary side winding L _S . When the low voltage switch S _{1 is} turned on, the secondary side winding L _S stores a potential difference. When the low voltage switch S _{1 is} turned on, the primary side winding continues to flow. The potential difference is 300 to the low voltage supply load. When the step-down switch S _{2 is} turned on, the energy stored in the medium-voltage capacitor C ₂ is transmitted to the low-voltage power source load 300 through the step-down inductor L _P . When switch S ₁ is at a low pressure is turned off, the first auxiliary inductor L _aux first auxiliary power supply circuit of the stored energy of the secondary winding L _S released, and based on the energy of the secondary winding and a first auxiliary inductor L _S L _aux release The first auxiliary voltage V _{O 3 is} output.

Further, clamp circuit 304 is the use of the clamp capacitor C ₁ the absorbent stored in _a leakage inductance energy of the low pressure switch S at the instant when the deadline, and to the leakage inductance the energy freewheeling completed, clamp circuit 304 releases the clamp capacitor C ₁ stored energy To medium voltage circuit.

For convenience of description of the present embodiment, it is assumed here that the low-voltage power supply load 300 is a reversible solid oxide fuel cell in an electrolytic energy storage state, the high-voltage power supply load 301 is assumed to be a DC bus load, and the load of the first auxiliary power supply circuit 307 is R _{O 3 .} A lithium battery. When the power supply is in the low voltage circuit, it means that the reversible solid oxide fuel cell energy of the low voltage power supply load 300 is boosted by the coupled inductor T _r to provide power to the DC bus bar V _bus at the high voltage power supply load 301. In addition, the above-mentioned reversible solid oxide fuel cell can operate in the state of energy storage or release, and can additionally generate a set of power output through the first auxiliary power circuit 307 to supply the operation of the reversible solid oxide fuel cell peripheral system. Voltage usage.

FIG. 4(a) is a diagram showing an equivalent circuit diagram of the reversible single-input multi-output DC converter operating in a high-voltage to low-voltage mode according to an embodiment of the present invention. Please refer to the figure 4(a). If the above reversible solid oxide fuel cell is taken as an example, the above equivalent circuit diagram indicates that the power is supplied from the high voltage side to the low voltage side of the reversible solid oxide fuel cell for supplying the low voltage side. Reversible solid oxide fuel cells are used for electrolytic energy storage. The above-mentioned coupled inductor T _r can be equivalent to the primary side winding L _P , the secondary side winding L _S , the secondary side magnetizing inductance L _ms and the secondary side leakage inductance L _ks in this equivalent circuit, wherein the secondary side winding The turns ratio of L _S to the primary side winding L _P is N , where N = N ₂ / N ₁ , N ₁ is the number of primary side coils, and N ₂ is the number of secondary side coils. Let V _Lp and V _Ls be the voltages of the primary side and secondary windings L _P and L _S of the coupled inductor respectively, then the relationship between them is: V _Ls / V _Lp = N (1)

The coupling coefficient k of the coupled inductor T _r is defined as k = L _ms /( L _ks + L _ms ) (2)

FIG. 4(b) is an equivalent circuit diagram of the reversible single-input multi-output DC converter operating in the low-voltage to high-voltage mode according to an embodiment of the present invention. Referring to FIG. 4(b), if the above-mentioned reversible solid oxide fuel cell is taken as an example, the above equivalent circuit diagram shows that the above-mentioned reversible solid oxide fuel cell generates electricity and releases energy to the load on the high pressure side. In this circuit, the coupled inductor T _r can be equivalent to the primary side winding L _P , the secondary side winding L _S , the primary side exciting inductance L _{mp ,} and the primary side leakage inductance L _kp , and the coupling coefficient k of the coupled inductor T _r is also Can be defined as k = L _mp /( L _kp + L _mp ) (3)

In order to enable those skilled in the art to understand the spirit of the present invention, the operation of the equivalent circuit of FIG. 4(a) will be described in detail step by step.

FIG. 5 is a diagram showing voltage and current timing waveforms of a reversible single-input multi-output DC converter operating in a high-voltage to low-voltage mode according to an embodiment of the invention. FIG. 6 is a diagram showing the circuit operation mode analysis of the reversible single-input multi-output DC converter operating in the high-voltage to low-voltage mode according to an embodiment of the invention. Please refer to section 4 (a), and FIG. 5 and FIG. 6, the following analysis with reference to the first 4 (a), FIG fifth and sixth diagram includes, wherein the low pressure switch S driver of _a signal T ₁ It is in phase with the driving signal T _{2 of the} buck switch S ₂ . In addition, the driving signal T _{1 is} complementary to the driving signal T _{3 of the} high voltage switch S ₃ . The duty cycle of the high voltage switch S _{3 is} defined as d ₃ , and the duty cycle of the low voltage switch S ₁ and the buck switch S ₂ is d ₁ , and the switching cycle is defined as T _s . Further, in the circuit of the fourth (a) diagram, the clamp capacitor C ₁ and the medium voltage capacitor C ₂ are equivalent to the voltage sources V _{c 1} and V _{c 2 , respectively} .

Mode 1 [ t ₀ ~ t ₁ ]: After the high voltage switch S ₃ has been turned on for a period of time, the on current of the high voltage switch S ₃ passes from the DC bus voltage V _{bus of the} high voltage circuit through the medium voltage circuit medium voltage capacitor C ₂ and T _r of the secondary side of the coupled inductor winding L _S, and finally by the primary winding side of the low-voltage circuit coupled inductor L _p T _r of the outflow end to the low pressure circuit. The high-voltage end portion of the energy is split by the secondary side winding of the coupled inductor T _r through the first auxiliary inductor L _aux and the first auxiliary diode D ₄ to the load R _{O 3} to which the auxiliary power supply terminal is coupled (for example Small capacity lithium battery) for charging. This mode can be regarded as the DC bus voltage V _bus of the high voltage circuit is excited by the magnetizing inductance L _{ms of the} secondary winding of the coupled inductor, and the medium voltage capacitor C ₂ and the reversible solid oxide fuel cell V _{FC of the} low voltage circuit are used for electrolysis. The power required. In addition, the current i _{L 2} of the step-down circuit is supplied from the step-down inductor L ₂ through the circuit of the step-down diode D ₂ to provide the power required for electrolysis of the reversible solid oxide fuel cell V _{FC of the} low voltage circuit. In one mode of operation, the input voltage V _bus of the high-voltage circuit may be expressed _{as: V bus = V C 2 -} V Lks - V Ls - V Lp + V FC (4)

The primary side voltage of the coupled inductor can be expressed as V _Lp = (1/ N ) V _Ls ; the leakage inductance voltage can be expressed as V _Lks = V _Ls (1- k ) / k . From the above, equation (4) can be rewritten as: V _bus = V _{C 2} - V _Ls (1- k ) / k - V _Ls - (1/ N ) V _Ls + V _FC = V _{C 2} + V _FC - V _Ls ( N + k ) / kN (5)

The voltage of the secondary side magnetizing inductance L _ms is equal to the voltage V _{Ls of the} secondary winding of the coupled inductor, according to formula (5): V _Ls = kN ( V _{C 2} + V _FC - V _bus ) / ( N + k ) (6)

Mode 2 [ t ₁ ~ t ₂ ]: At the moment when the high-voltage switch S _{3 is} turned off (t=t ₁ ), since the secondary side winding leakage inductance L _ks still needs energy to be released, its current cannot be instantaneously changed, therefore, the second clamping The diode D _{3 is} naturally turned on, and the current i _{Lks of the} secondary side winding leakage inductance flows through the path of the second clamp diode D ₃ and the clamp capacitor C ₁ to release the leakage inductance power, and the current i _{Lks is} gradually reduced. . When the high voltage switch S ₃ is turned off, its voltage across is V _bus - V _{C 1} . Since the sense value of the secondary side magnetizing inductance L _ms is much larger than the leakage inductance L _{ks of the} secondary side winding, the current i _{Lms of the} secondary side magnetizing inductance can be regarded as a constant current. Since the slope of the current i _Lms of the secondary side magnetizing inductance is much smaller than the slope of the secondary side winding leakage inductor current i _Lks , the parasitic diode of the low voltage switch S ₁ is naturally turned on to receive the coupled inductor primary winding current i _{The difference between Lp} and the secondary side winding leakage inductance current i _Lks . In this mode 2, the first auxiliary inductance L _aus in the first auxiliary power supply circuit still has energy to be released, and the floating load of the load R _{O 3} of the small-capacity lithium battery is continuously floated. The current i _{L 2} of the step-down circuit is provided by the step-down inductor L ₂ through the loop provided by the step-down diode D ₂ , and is continuously discharged to the low-voltage circuit to provide the energy required for the electrolytic storage of the reversible solid oxide fuel cell. electric power.

Mode 3 [ t ₂ ~ t ₃ ]: When time ( t = t ₂ ), the low voltage switch S ₁ and the step-down switch S _{2 are} turned on. In the former mode 2, the parasitic diode of the low-voltage switch S ₁ is turned on. At the beginning of this mode, the low-voltage switch S _{1 is} directly turned on, and the synchronous rectification technology is used to greatly reduce the parasitic diode of the low-voltage switch S ₁ with high inflow current. Turn on the loss and achieve the effect of Zero Voltage Switching (ZVS). The current i _{Lms of the} secondary side magnetizing inductance L _ms is in the operation mode of the flyback power converter, and the energy is released by magnetic coupling through the secondary side L _{S of the} coupled inductor to induce the primary side current i _Lp . The primary side current i _Lp provides a reversible solid oxide fuel cell for electrolytically storing power through the low voltage switch S ₁ . After the buck switch S _{2 is} turned on, the voltage V _{C 1} of the clamp capacitor charges the step-down inductor L ₂ of the step-down circuit and provides the power required for the electrolytic storage of the reversible solid oxide fuel cell. In addition, the energy stored in the medium voltage capacitor C ₂ is in this mode and the voltage V _{C 1 of the} clamp capacitor C ₁ is supplied to the step-down inductor L ₂ and to the low voltage terminal V _FC . In addition, in this mode, the first auxiliary inductor L _aux has energy to be released, and continuously supplies power to the first auxiliary power terminal V _{O 3} , and waits for the first auxiliary inductor L _aux current to decrease to zero to end the mode.

Mode 4 [ t ₃ ~ t ₄ ]: When time ( t = t ₃ ), i _{aux is} reduced to zero. As in the previous mode, the secondary side magnetizing inductor current i _Lms releases the energy by magnetic coupling through the secondary side L _{S of the} coupled inductor in the operation mode of the flyback power converter, inducing the primary side current i _Lp . This primary side current i _Lp flows out of the low voltage switch S ₁ to provide power for electrolysis of the reversible solid oxide fuel cell. At the same time, the clamp capacitor voltage V _{C 1} charges the step-down inductor L ₂ of the step-down circuit and provides power for electrolysis of the reversible solid oxide fuel cell. Furthermore, the energy stored in the medium voltage capacitor C ₂ is in this mode together with the clamp capacitor voltage V _{C 1} and supplies the step-down inductor L ₂ and the low voltage terminal. In this mode, the voltage equation of the coupled inductor and the secondary winding voltage can be expressed as V _FC = v _Lp + v _Ls + v _Lks - V _{C 2} + V _{C 1} (7)

The secondary side magnetizing inductance L _ms voltage is equal to the voltage v _{Ls of the} secondary winding of the coupled inductor, and according to equation (7), v _Ls = kN ( V _FC + V _{C 2} - V _{C 1} ) / ( N + k ) 8)

At this time, the voltage v _{Lp of the} primary winding of the coupled inductor is equal to the reversible solid oxide fuel cell voltage V _FC , so equation (8) can be rewritten as V _FC = k ( V _{C 2} - V _{C 1} )/ N (9)

Mode 5 [ t ₄ ~ t ₅ ]: When time ( t = t ₄ ), the low voltage switch S ₁ and the step-down switch S _{2 are} turned off. The current i _{L 2 of the} step-down inductor L ₂ must be continuous, and the step-down diode D _{2 is} naturally turned on. Similarly, the secondary-side leakage inductance L _Lks current i _Lks also requires continuous, high voltage and therefore the parasitic diode switch S ₃ is turned on to hold the natural leakage inductance L _Lks i _Lks continuous current. Further, the current i _{Lks of the} above leakage inductance L _Lks is returned to the power supply terminal V _{bus on the} high voltage side. Since the DC bus voltage V _bus is much higher than the fuel cell voltage V _FC, the voltage across the coupled inductor T _r instantly reversed polarity, a coupled inductor current i L _P of the primary winding _Lp and the secondary leakage inductance of the current i the slope _Lks also to reverse growth, low pressure switch S ₁ is the parasitic diode natural conduction to undertake the primary side and the secondary side current of the coupled inductor T _r.

Model 6 [] t ₅ ~ t _6: the high voltage switch is turned on when the parasitic diode of S _3, S ₃ at both ends of the high voltage switch ideally zero cross voltage. At the same time, the high voltage switch S ₃ is triggered to be turned on, thus achieving the effect of Zero Voltage Switching (ZVS). Since each of the previous mode current element has wheeling mode to a terminal, coupled with high-voltage switch S ₃ is turned on, there is provided a coupled inductor T _r excitation path, the secondary winding magnetizing inductance L _ms excitation Jiangzai accepted, for reversible solid The current i _Lp of the primary winding of the oxide fuel cell terminal will gradually decrease. Due to the influence of the excitation of the secondary side winding magnetizing inductance L _ms , the non-polar point voltage of the primary winding is positive, the parasitic diode of the low voltage switch S ₁ is turned off, and the primary winding current i _Lp starts to charge the parasitic capacitance of the low voltage switch S ₁ . . Since the parasitic capacitance of the low-voltage switch S ₁ is larger than that of the general high-voltage switch, and the residual charge on the parasitic diode must be removed, the required charging current is higher when the voltage across the two terminals rises.

Mode seven [t ₆ ~ t _7]: when the time t = t _6, the voltage across the low-voltage switch S ₁ is higher than the voltage of the clamp capacitor C _{1 C 1} V, so that the first clamping diode D ₁ is turned on, and therefore, previous The charge charged to the parasitic capacitance of the low voltage switch S ₁ is introduced into the clamp capacitor C ₁ . At the same time, part of the energy charges the first auxiliary inductance L _aux , at which time the first auxiliary diode D _{4 is} naturally turned on to release energy to the first auxiliary power supply circuit output terminal V _{O 3} . When the first clamp diode D _{1 is} turned off, the switching cycle is completed, and then the mode is returned to mode one. In the seventh mode, according to the voltage loop, the voltage of the secondary side magnetizing inductance L _ms can also be expressed as the above formula (5), and the voltage of the clamp capacitor V _{C 1} can be expressed as V _{C 1} = k ( V _bus - V _FC - V _{C 1} ) / ( N + k ) + V _FC (10)

In a preferred embodiment, the coupled inductor T _{r is} sandwiched and wound, the coil coupling effect is good, and the leakage inductance energy of the coupled inductor T _r is small relative to the iron powder core, as long as the voltage clamping effect is fully absorbed. Leakage energy has little effect on system voltage. To simplify the mathematical equations and facilitate theoretical analysis, the coupling coefficient k is defined as 1. In addition, assuming that the dead time is very short, the combination of the low-voltage switch conduction duty cycle and the high-voltage switch conduction duty cycle can be approximately 1, that is, d ₁ + d ₃ =1. According to the Volt-Second Balance, through the balance of the secondary side magnetizing inductance L _ms voltage volt-second, equation (6) and equation (8), we can deduce: ( V _FC + V _{C 2} - V _bus ) × d ₃ +( V _FC + V _{C 2} - V _{C 1} ) × (1 - d ₃ ) = 0 (11)

Similarly, according to the voltage volt-second balance of the buck inductor L ₂ , it can be derived: V _{C 1} = V _FC /(1- d ₃ ) (12)

According to equations (9), (11) and (12), the step-down ratio G _{V 1} can be calculated as follows: G _{V 1} = V _FC / V _bus = d ₃ × (1 - d ₃ ) / [ N (1- d ₃ )+1] (13)

The above embodiment illustrates the manner in which power is supplied from the high pressure side to the low pressure side. The operation of supplying electric power from the low pressure side to the high pressure side will be described below.

FIG. 7 is a diagram showing voltage and current timing waveforms of a reversible single-input multi-output DC converter operating in a low-voltage to high-voltage mode according to an embodiment of the invention. FIG. 8 is a diagram showing the circuit operation mode analysis of the reversible single-input multi-output DC converter operating in the low-voltage to high-voltage mode according to an embodiment of the invention. Please also refer to the equivalent circuit shown in Figure 4(b), the circuit timing in Figure 7, and the circuit operation mode in Figure 8. For convenience of explanation, the duty cycle of the low-voltage switch S ₁ is defined as d ₁ , and the switching cycle T _S is as follows. Since the power is supplied from the low-voltage side to the high-voltage side, it is only necessary to drive the low-voltage switch S ₁ and the high-voltage switch S ₃ , and the step-down circuit does not need to operate. In other words, the step-down inductor L ₂ , the step-down diode D _{2 ,} and the step-down switch S ₂ do not operate. The step-down circuit portion of the circuit of Fig. 4(b) is indicated by a broken line.

Mode 1 [ t ₀ ~ t ₁ ]: When t = t ₀ , the low-voltage switch S ₁ has been turned on for a period of time, at this time, the magnetizing inductance L of the primary side of the coupled inductor T _r of the reversible solid oxide fuel cell V _{FC The mp} is charged and charged. The coupled inductor T _r is magnetically induced to release the energy V _{C 1} stored by the clamp capacitor C ₁ to the medium voltage capacitor C ₂ , and the current on the low voltage switch S ₁ can be expressed as i _{S 1} = i _Lkp - i _Ls , The current i _Ls on the secondary side of the coupled inductor T _r is negative, and the current magnitude i _{Ls is} also gradually decreased as the energy of the voltage V _{C 1} of the clamp capacitor C ₁ is released. In this mode 1, the first auxiliary inductance L _aux in the first auxiliary power supply circuit is still performing energy release, and the mode 1 is ended when the energy of the first auxiliary inductance L _aux is released.

Mode 2 [ t ₁ ~ t ₂ ]: When t = t ₁ , the current i _{Laux of the} first auxiliary inductance L _aux is reduced to zero. The previous model a same reversible solid oxide fuel cell V _FC still on the magnetizing inductance of the primary side of the coupled inductor T _r of L _mp are energized charge coupled inductor T _r and transmitted through the magnetic induction, the clamp capacitor C ₁ stored The energy V _{C 1 is} released to the medium voltage capacitor C ₂ (voltage V _{C 2} ), and the current on the low voltage switch S ₁ can be expressed as i _{S 1} = i _Lkp - i _Ls , where the secondary side of the coupled inductor T _r The current i _Ls is negative, and its current magnitude i _{Ls is} also gradually reduced as the energy of the voltage V _{C 1} of the clamp capacitor C ₁ is released. When the voltage V _{C 1 of the} clamp capacitor C ₁ releases energy, the mode 2 is ended. In mode one and mode two, the circuit loop equation can be expressed as: V _FC = v _Lp + v _Ls + v _Lks - V _{C 2} + V _{C 1} (14)

The voltage v _Ls on the secondary side of the coupled inductor T _r and the voltage v _{Lkp of the} leakage inductance can be expressed as V _Ls = Nv _Lp , v _Lkp = v _Lp × (1 - K ) / k , respectively, and the equation (14) can be Rewritten as: V _FC = V _{C 1} - V _{C 2} + v _Lp + N × v _Lp + v _Lp × (1- k ) / k (15)

Voltage magnetizing inductance on the primary side of the coupled inductor T _r of L _mp is equal to coupled inductor T _r of the primary voltage v winding of _Lp, according to formula (15) can be obtained _{v Lp = k × (V FC} + V C 2 - V C ₁ )/(1- Nk ) (16)

Further, the leakage inductance of the primary voltage v _Lkp side of the coupled inductor voltage v _Lmp magnetizing inductance of the primary side of the coupled inductor T _r and T _r exactly equal to the voltage V _FC reversible solid oxide fuel cell. Voltage side of the secondary loop Coupled inductor T _r, availability clamp capacitor voltage V _{C 1} C ₁ and C ₂ MV capacitor voltage V _{C 2} of the following _{relationship: V C 2 = v Ls +} V C ₁ = N × k × V _FC + V _{C 1} (17)

Mode 3 [ t ₂ ~ t ₃ ]: When time t = t ₂ , the clamp capacitor C ₁ releases energy (voltage V _{C 1} ), and the secondary side current i _{Ls of the} coupled inductor T _r decreases to zero. At this time, the second clamp diode D _{3 is} reverse biased. In this mode, the reversible solid oxide fuel cell V _FC, which can be regarded as a low voltage circuit, excites the magnetizing inductance L _mp and the leakage inductance L _kp of the primary winding of the coupled inductor T _r .

Mode 4 [ t ₃ ~ t ₄ ]: When time t = t ₃ , the low voltage switch S ₁ is turned off. When coupled inductor T _r of the primary-side current is induced L _S i _Ls of the secondary side of the coupled inductor T _r, S ₃ of the high-voltage switch parasitic diode natural conduction, the reversible solid oxide fuel cell, and the coupled inductor The energy of the medium voltage capacitor C ₂ is also transmitted to the DC bus ( V _bus ). The leakage inductance energy charges the clamp capacitor C ₁ (voltage V _{C 1} ), and part of the energy is transmitted to the first auxiliary power terminal via the first auxiliary inductor L _aux and the first auxiliary diode D ₄ . In this mode, the voltage equation of the voltage of the primary side winding and the secondary side winding of the coupled inductor T _r can be expressed as: V _FC = v _Lkp + v _Ls + v _Lp + V _bus - V _{C 2} (18)

Voltage magnetizing inductance on the primary side of the coupled inductor T _r of L _mp is equal to coupled inductor T _r of the primary voltage v winding of _Lp, according to formula (18) can be obtained _{v Lp = k × (V FC} + V C 2 - V bus )/(1- Nk ) (19)

A low pressure switch S ₁ is turned off, the voltage across capacitor C is equal to the clamp voltage V _{C 1 1} in. According to the voltage loop equation, the voltage V _{C 1 of the} clamp capacitor C ₁ can be calculated by the following equation: V _{C 1} = (V _bus - V _FC - V _{C 2} ) / (1 - Nk ) + V _FC (20)

Model 5 t ₄ ~ t ₅ []: Since mode four, the primary side of the inductive coupled inductor T _r of the secondary-side current i _Ls of coupled inductor T _r, the high voltage switch S ₃ of the parasitic diode natural conduction. At the same time, the high-voltage switch S ₃ is triggered and turned on, and the synchronous rectification technology is used to greatly reduce the conduction loss of the diode, and the reversible solid oxide fuel cell, the coupled inductor and the medium-voltage capacitor C ₂ energy are continuously transmitted. To the DC bus ( V _bus ). In addition, the energy of the reversible solid oxide fuel cell, the primary side winding L _{P of the} coupled inductor T _r , and the first auxiliary inductor L _aux is transmitted to the first auxiliary power terminal V _{O 3} through the first auxiliary diode D ₄ . until the first clamping diode D ₁ is turned off, this mode ends.

Model 6 [t ₅ ~ t _6]: when the time t = t _5, the leakage inductance L _{kp 1} (voltage V _{C 1)} for release of the energy is completed clamp capacitor C, Groups clamping diode D the current i _{D 1 1} Decrease to zero, at which point the first clamp diode D _{1 is} reverse biased. In this mode, the reversible solid oxide fuel cell V _{FC of the} low voltage circuit is coupled in series with the primary side winding of the inductor T _r , the secondary side winding, and the medium voltage capacitor C ₂ , and releases energy to the output DC bus. In addition, the reversible solid oxide fuel cell V _{FC of the} low voltage circuit is coupled in series with the primary side winding of the inductor T _r , the first auxiliary inductor L _aux and the first auxiliary diode D ₄ , and outputs the first auxiliary power source V _{O . 3} release energy.

Mode 7 [ t ₆ ~ t ₇ ]: When time t = t ₆ , the high voltage switch S ₃ is turned off, the energy in the coupled inductor T _r is continuously released, so the parasitic diode of the high voltage switch S ₃ is naturally turned on to make the current continuous , release energy to the DC bus. Therefore, in this mode, the primary side winding, the secondary side winding, and the medium voltage capacitor of the V _FC series coupled inductor T _r of the reversible solid oxide fuel cell of the low voltage circuit are still the output DC bus ( V _Bus ) releases energy. In addition, the fuel cell V _{FC of the} low voltage circuit is coupled in series with the primary winding of the inductor T _r , the first auxiliary inductor L _aux and the first auxiliary diode D ₄ , and releases energy to the output first auxiliary power source V _{O 3} .

Mode VIII [ t ₇ ~ t ₈ ]: When time t = t ₇ , the low voltage switch S _{1 is} turned on. The parasitic diode of the high voltage switch S ₃ is continuously turned on, and the voltages of the primary side L _p and the leakage inductance L _kp of the coupled inductor T _r are instantaneously reversed, so that the current i _{Ls for} releasing energy to the output DC bus is gradually reduced. At this time, the current of the first auxiliary inductor L _aux of the first auxiliary power supply circuit continues to flow and the first auxiliary diode D ₄ is also continuously turned on. Primary-side leakage inductance L _kp eight in this mode, since the first clamping diode D ₁ and no reverse recovery current coupled inductor T _r limits the rate of rise of the primary current i _Lp, resulting in eight this mode, a low pressure switch The S ₁ conduction instant cannot get current from any path, forming a natural Zero Current Switching (ZCS) phenomenon. Therefore, the switching loss is alleviated.

Mode IX [ t ₈ ~ t ₉ ]:: When time t = t ₈ , the current i _Ls outputted to the DC busbar is gradually reduced to zero, after which the secondary winding current i _Ls is negative. Since the parasitic diode on the high voltage switch S ₃ is turned on in mode VIII, the residual charge on the parasitic diode must be removed when the high voltage switch S ₃ is turned off. Therefore, when both ends of the high voltage switch S ₃ rise across the voltage, the required charging current is high. When the voltage across the high voltage switch S ₃ is raised to V _bus - V _{C 1} , the second clamp diode D _{3 is} turned on, the switching cycle is completed, and then the mode is returned to mode one.

According to the above, since the coupled inductor T _r adopts the sandwich winding method, the coil coupling effect is good, and the leakage inductance energy of the coupled inductor has a small capacity relative to the iron powder core, as long as the voltage clamping effect is fully performed, the leakage energy is fully absorbed, for the system The influence of voltage is not high. In order to simplify the mathematical equation and facilitate theoretical analysis, the coupling coefficient k is defined as 1. According to the Volt-Second Balance theory, the primary side of the coupled inductor T _r is excited by the magnetic inductance L _mp . The average voltage is zero, and the relationship can be expressed as: V _FC × d ₁ × T _S + ( V _FC - V _{C 1} ) × (1 - d ₁ ) × T _S =0 (21)

According to formula (21), the clamp capacitor voltage V _{C 1} is obtained as follows: V _{C 1} = V _FC /(1- d ₁ ) (22)

Therefore, the voltage of the primary side inductance L _mp of the coupled inductor T _r of mode 5 is v _Lmp = V _FC - V _{C 1} = [- d ₁ /(1 - d ₁ )] V _FC (23)

The output DC bus voltage of mode 5 can be expressed as V _bus = V _{C 1} + V _{C 2} - v _Ls (24)

According to the voltage v _Ls = Nv _Lmp of the secondary winding of the coupled inductor T _r , and the equations (17) and (22) are substituted into the equation (24), the boost ratio G _{V 2} can be obtained as follows: G _{V 2} = V _bus / V _FC =(2+ N )/(1- d ₁ ) (25)

The time for defining the interval between mode one and mode nine is d _x × T _S =[( t ₉ - t ₈ )+( t ₁ - t ₀ )], according to the volt-second balance theory, the first auxiliary inductance L in one cycle The average voltage of _aux is zero, and the relationship can be expressed as follows: ( V _FC - V _Lmp - V _{O 3} ) × (1 - d ₁ ) × T _S + (- V _{O 3} ) × d _x × T _S =0 (26)

Substituting equation (23) into equation (26) yields: G _VL = V _O3 / V _FC =1/(1- d ₁ + d _x ) (27)

The average current of diode D ₄ can be expressed as

Also, the maximum auxiliary inductor current can be described as i _Laux =( V _{O 3} / L _aux )× d _x × T _S (29)

Substituting equation (29) into equation (28)

Let the average current of the first auxiliary diode D ₄ be equal to the load current of the first auxiliary power supply circuit i _{D 4 ( avg )} = ( V _{O 3} / R _{O 3} ) (31)

From equation (30) and equation (31), you can find

Substituting equation (32) into equation (27), the boost ratio G _{VL of the} low voltage circuit to the first auxiliary power supply circuit can be expressed as follows:

From the above two operations and two mathematical analysis, it can be seen that the present application additionally designs a first auxiliary power supply circuit. In addition to providing additional load, the first auxiliary power supply circuit actually has the function of assisting zero voltage switching and zero current switching. Moreover, in general, multi-output power systems often have fixed loads that do not change. For example, electric motorcycles are powered by lead-acid batteries. In addition to supplying motors that require high voltages, they also need to supply loads such as dashboards, headlights, indicator lights, etc., and the power consumed by these loads is fixed. . Therefore, the architecture of the first auxiliary power supply circuit proposed in this embodiment can provide excess power to other loads during the power supply process. In addition, it can be seen from the above circuit operation that the first auxiliary power source is The voltage of the circuit is determined by the first auxiliary inductor, the load and the duty cycle. Therefore, the first auxiliary power supply circuit does not affect the power supply.

In the circuit architecture of the above embodiment, although only one auxiliary power supply circuit is disclosed, it should be understood by those skilled in the art that the circuit architecture of the present invention can also add multiple sets of auxiliary power supply circuits. Multiple sets of auxiliary power circuits can provide multiple loads in a powered system. For example, the circuit diagram of FIG. 1 can be further added with a second auxiliary power supply circuit. As shown in FIG. 9, FIG. 9 is a circuit diagram of a high efficiency reversible single input multi-output DC power converter according to another embodiment of the present invention. Referring to FIG. 9, in this example, a second auxiliary power supply circuit 901 is additionally added. The second auxiliary power supply circuit includes, for example, a second auxiliary inductance L _{aux 2} , a second auxiliary diode D ₅ , a second auxiliary filter capacitor C ₄ and a second auxiliary power supply load R _{O 4} . The first end of the second auxiliary inductor L _{aux 2} is coupled to a node where the low voltage switch S ₁ is coupled to the anode of the first clamp diode D ₁ . The second end of the second auxiliary inductor L _{aux 2} is coupled to the anode of the second auxiliary diode D ₅ . The second auxiliary cathode of diode D is coupled to a first end of the ₅ second auxiliary filter capacitor C _4, the second terminal of the second auxiliary filter capacitor C ₄ is coupled to a common voltage terminal. In addition, the second auxiliary power supply load R _{O 4 is} connected in parallel with the second auxiliary filter capacitor C ₄ . Therefore, the present invention does not limit the number of auxiliary power supply circuits.

In addition, although the above embodiment is exemplified by an electrolytic energy storage and discharge energy release system of a reversible solid oxide fuel cell, those skilled in the art should be able to understand that the present application should not be limited only to "reversible solid state oxidation." Electrolytic energy storage and discharge energy release of fuel cells, this case can also be applied to electric motorcycles or other multi-output electricity The battery is charged and discharged on the battery, and therefore, the invention is not limited thereto.

Simulation result

To further verify the high efficiency reversible single input multiple output DC converter architecture of embodiments of the present invention. In this simulation, the input power supply uses 12V DC power supply (similar to the output voltage of the reversible solid oxide fuel cell), the output high voltage is set to 200V, and the output auxiliary voltage is set to 24~28V for battery floating charge. . When the reversible solid oxide fuel cell requires electrolytic energy storage, the output voltage of the low voltage side requires 1.5 times to 2 times the power of the original input power source. Therefore, when operating in the high voltage to low voltage mode, the output voltage of the low voltage power supply terminal The design range is from 18V to 24V.

FIG. 10 is a diagram showing conversion efficiency of a high efficiency reversible single input multi-output DC converter according to an embodiment of the present invention. Please refer to Figure 10, sub-graph (a) shows the power conversion efficiency of the fuel cell electrolytic energy storage state (high voltage to low voltage mode). The test conditions are that the voltage required for the fuel cell to store energy is 18~24V and the other output is 24~28V for the small capacity lithium battery and the converter output voltage is 200V. The maximum conversion efficiency in this operating state can be higher than 96%; the sub-graph (b) represents the power conversion efficiency of the fuel cell discharge state (operating in the low-voltage to high-voltage mode), and the test condition is that the fuel cell voltage is 12V to generate a set of high-voltage outputs. The voltage is 200V and a set of voltages for floating the small capacity lithium battery is 24~28V. In this operating state, the maximum conversion efficiency can be higher than 97%. From Fig. 10, it can be verified that the high efficiency reversible single input multi-output DC converter proposed by the embodiment of the present invention has the characteristics of high power conversion efficiency.

In summary, the spirit of the present invention lies in the high In the efficiency reversible single-input multi-output DC converter, the coupled inductor is designed and the boosting ratio is increased by using the coupled inductor. In addition, at least one auxiliary auxiliary auxiliary power source is additionally added to the coupling of the clamping circuit and the low voltage switch. The high-efficiency reversible single-input multi-output DC converter uses the characteristic of continuous leakage of the leakage inductance current of the coupled inductor to achieve a flexible switching effect of the switch, thereby reducing switching loss. And the additional problem is that the output diode has no reverse recovery current and the power conversion efficiency is improved. In addition, the output voltage of the auxiliary power supply to the auxiliary battery can be designed to vary within a preset range from light load to heavy load variation.

The specific embodiments of the present invention are intended to be illustrative only and not to limit the invention to the above embodiments, without departing from the spirit of the invention and the following claims. The scope of the invention and the various changes made are within the scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

300‧‧‧Low-voltage power supply load

301‧‧‧High voltage power supply load

302‧‧‧Low voltage circuit

303‧‧‧ medium voltage circuit

304‧‧‧Clamping circuit

305‧‧‧High voltage circuit

306‧‧‧Buck circuit

307‧‧‧First auxiliary power supply circuit

308‧‧‧Control circuit

S ₁ ‧‧‧ low voltage switch

C _FC ‧‧‧first filter capacitor

T _r ‧‧‧coupled inductor

L _P ‧‧‧ primary winding coupled inductor T _r of

L _S ‧‧‧ secondary winding coupled inductor T _r of

C ₂ ‧‧‧ medium voltage capacitor

C ₁ ‧‧‧Clamping capacitor

D ₁ ‧‧‧First clamped diode

D ₃ ‧‧‧Second clamped diode

S ₃ ‧‧‧High voltage switch

C _bus ‧‧‧second filter capacitor

S ₂ ‧‧‧Buck Switch

L ₂ ‧‧‧Buck Inductance

D ₂ ‧‧‧Bucking diode

L _aux ‧‧‧First auxiliary inductor

C ₃ ‧‧‧First auxiliary filter capacitor

D ₄ ‧‧‧First auxiliary diode

R _{O 3} ‧‧‧Auxiliary power equivalent load

Claims (10)

A high-efficiency reversible single-input multi-output DC converter includes: a low-voltage power supply load including a low-voltage power supply input and output terminal and a common voltage terminal; a high-voltage power supply load including a high-voltage power supply input and output terminal and the common voltage a coupled inductor includes a primary side winding and a secondary side winding; a low voltage circuit comprising: a first filter capacitor comprising a first end and a second end, the first end of which is coupled to the low voltage a low-voltage power supply input end of the power load, the second end of which is coupled to the common voltage end of the low-voltage power load; a low-voltage switch includes a first end and a second end, the second end of which is coupled to the low-voltage power load The first side winding of the coupled inductor includes a first end and a second end, the first end of which is coupled to the low voltage power input and output end of the low voltage power supply, and the second end is coupled to the low voltage a first end of the switch; the intermediate voltage circuit includes: a secondary side winding of the coupled inductor, including a first end and a second end, the first end of which is coupled to the first end of the low voltage switch; Medium pressure a first end and a second end, the first end of which is coupled to the second end of the secondary winding of the coupled inductor; a high voltage circuit comprising: a second filter capacitor including a first end and Second end, its The first end is coupled to the high voltage power supply input and output end of the high voltage power supply, and the second end is coupled to the common voltage end of the high voltage power load; a high voltage switch includes a first end and a second end, the first The second end is coupled to the second end of the medium voltage capacitor, and the second end is coupled to the high voltage power supply input and output end of the high voltage power supply load; the buck circuit comprises: a buck switch, including a first end and a first end a second end, the first end of which is coupled to the second end of the medium voltage capacitor; a step-down diode comprising an anode and a cathode, the anode of which is coupled to the common voltage end of the high voltage power supply load, and The cathode is coupled to the second end of the buck switch; and a buck inductor includes a first end and a second end, the first end of which is coupled to the second end of the buck switch, and the second end is coupled a low-voltage power supply input and output terminal connected to the low-voltage power supply; a first auxiliary power supply circuit coupled to the low-voltage circuit and having a first auxiliary inductance; and a control circuit for controlling the low-voltage switch, the high-voltage switch, and the drop The on and off of the pressure switch, wherein, at a low pressure In the mode: the control circuit controls the low voltage switch and the high voltage switch according to the state of the high voltage power load, and the control circuit keeps the buck switch in an off state; when the low voltage switch is turned on, the primary side winding stores energy in a In the first magnetizing inductance, the primary winding is turned off when the low voltage switch is turned off And releasing the energy stored in the first magnetizing inductance; the secondary winding generates a potential difference through mutual inductance with the primary winding, and when the low voltage switch is turned on, the secondary winding stores the potential difference to the medium piezoelectric Capacitating, when the low voltage switch is turned off, the secondary side winding continues to flow the potential difference to the medium voltage capacitor; the high voltage switch receives the energy in the medium voltage capacitor, and accordingly outputs a second output voltage to the high voltage power supply The first auxiliary inductor of the first auxiliary power supply circuit stores the energy released by the primary side winding, and outputs an auxiliary voltage according to the energy released by the primary side winding and the first auxiliary inductor. Wherein, in a high voltage to low voltage mode: the control circuit controls the low voltage switch, the high voltage switch and the buck switch according to a state of the low voltage power load, wherein the low voltage switch and the buck switch are connected to each other Phase, and the low-voltage switch and the high-voltage switch are in anti-phase; when the high-voltage switch is turned on, the secondary winding stores energy in a second In the inductor, the primary side winding releases the energy stored in the second magnetizing inductance; the primary side winding generates a potential difference through mutual inductance with the secondary side winding, and when the low voltage switch is turned on, the secondary side winding stores The potential difference, when the low-voltage switch is turned on, the primary side winding continues to flow the potential difference to the low-voltage power supply load; when the buck switch is turned on, the energy stored in the medium-voltage capacitor And flowing through the buck inductor and the step-down diode to the low-voltage power supply load; when the buck switch is turned off, the buck inductor transmits the energy to the low-voltage power supply through the buck diode; When the low voltage switch is turned off, the first auxiliary inductor of the first auxiliary power supply circuit stores the energy released by the secondary side winding, and outputs the auxiliary voltage according to the energy released by the secondary side winding and the first auxiliary inductor. The first auxiliary power supply circuit is configured to provide the auxiliary voltage to drive the power coupled to the load of the first auxiliary power supply circuit, regardless of the low voltage to high voltage mode or the high voltage to low voltage mode. The high-efficiency reversible single-input multi-output DC converter according to the first aspect of the invention, wherein the first auxiliary power supply circuit comprises: the first auxiliary inductor, comprising a first end and a second end, wherein The first end is coupled to the first end of the low voltage switch; the first auxiliary diode includes an anode and a cathode, the anode of which is coupled to the second end of the first auxiliary inductor; and a first auxiliary filter capacitor, including a first end and a second end, the first end of which is coupled to the cathode of the first auxiliary diode, and the second end of which is coupled to the common voltage end of the low voltage power load; and a first auxiliary power load The first end is coupled to the cathode of the auxiliary diode, and the second end is coupled to the common voltage end of the low voltage power supply. The high-efficiency reversible single-input multi-output DC converter as recited in claim 1, further comprising: a second auxiliary power supply circuit, comprising: a second auxiliary inductor comprising a first end and a second end The first auxiliary end of the second auxiliary inductor is coupled to the first end of the low voltage switch; the second auxiliary diode includes an anode and a cathode, wherein the anode of the second auxiliary diode is coupled a second auxiliary auxiliary capacitor, the second auxiliary filter capacitor includes a first end and a second end, wherein the first end of the second auxiliary filter capacitor is coupled to the second auxiliary diode a cathode, wherein the second end of the second auxiliary filter capacitor is coupled to the common voltage terminal of the low voltage power supply load; and a second auxiliary power load includes a first end and a second end, wherein the second auxiliary The first end of the power supply load is coupled to the cathode of the second auxiliary diode, and the second end of the second auxiliary power load is coupled to the common voltage terminal of the low voltage power load. The high-efficiency reversible single-input multi-output DC converter according to the first aspect of the patent application, further comprising: a clamping circuit coupled between the low voltage circuit and the medium voltage circuit, having a clamp capacitor, The clamping capacitor absorbs the leakage energy stored in the momentary switch of the low voltage switch, and after the leakage energy is freewheeled, the clamping circuit releases the energy stored by the clamping capacitor to the medium voltage circuit. The high-efficiency reversible single-input multi-output DC converter according to the first aspect of the invention, wherein the clamping circuit comprises: a first clamping diode comprising an anode and a cathode, wherein the first clamping The anode of the diode is coupled to the first end of the low voltage switch; the clamp capacitor includes a first end and a second end, wherein the first end of the clamp capacitor is coupled to the cathode of the first clamp diode And the second end of the clamp capacitor is coupled to the common voltage terminal of the low voltage power supply load; and the second clamp diode includes an anode and a cathode, wherein the anode of the second clamp diode is coupled The first end of the capacitor is clamped, and the cathode of the second clamp diode is coupled to the second end of the medium voltage capacitor. The high-efficiency reversible single-input multi-output DC converter as recited in claim 1, wherein when the low-voltage power supply is supplied by the high-voltage power supply load, and the current of the primary-side winding of the coupled inductor is When the voltage terminal is connected to the low-voltage power supply and output terminal of the low-voltage power supply through the parasitic diode of the low-voltage switch, the control circuit controls the low-voltage switch to be turned on with the buck switch, so that the low-voltage switch reaches zero voltage switching (Zero Voltage Switching, ZVS). The high-efficiency reversible single-input multi-output DC converter as recited in claim 1, wherein when the low-voltage power supply is supplied by the high-voltage power supply load, and the low-voltage switch is turned off and coupled a leakage current of the secondary winding of the inductor, through the high voltage switch When the parasitic diode flows to the high-voltage power input and output end of the high-voltage power supply load, the control circuit controls the high-voltage switch to be turned on, so that the high-voltage switch reaches zero voltage switching (ZVS). The high-efficiency reversible single-input multi-output DC converter as recited in claim 1, wherein when the high-voltage power supply is powered by the low-voltage power supply load, and the low-voltage switch is turned off, and the two of the coupled inductors When the current of the secondary winding passes through the parasitic diode of the high voltage switch and continues to flow to the input and output end of the high voltage power supply of the high voltage power supply, the control circuit controls the high voltage switch to be turned on, so that the high voltage switch reaches zero voltage switching (Zero Voltage Switching, ZVS). The high-efficiency reversible single-input multi-output DC converter as recited in claim 1, wherein when the high-voltage power supply is powered by the low-voltage power supply load, and the high-voltage switch is turned off, and the two of the coupled inductors The current of the secondary winding passes through the parasitic diode of the high voltage switch, and continues to the high voltage power supply input and output end of the high voltage power supply load, and the first auxiliary inductor of the first auxiliary power supply circuit continues to flow, the control circuit The low voltage switch is controlled to be turned on, so that the low voltage switch reaches Zero Current Switching (ZCS). The high-efficiency reversible single-input multi-output DC converter as recited in claim 1 includes: a plurality of auxiliary power supply circuits, wherein each of the auxiliary power supply circuits respectively The method includes an auxiliary inductor including a first end and a second end, the first end of which is coupled to the first end of the low voltage switch, and an auxiliary diode including an anode and a cathode, the anode of which is coupled to the auxiliary The second end of the inductor; the auxiliary filter capacitor includes a first end and a second end, the first end of which is coupled to the cathode of the auxiliary diode, and the second end of which is coupled to the common connection of the low voltage power load And an auxiliary power supply load, comprising a first end and a second end, the first end of which is coupled to the cathode of the auxiliary diode, and the second end of which is coupled to the common voltage end of the low voltage power load .