CN108462397A - A kind of three road output DC-DC converter of hybrid modulation isolated form - Google Patents

Abstract

The invention discloses a hybrid modulation isolation type three-way output DC-DC converter, comprising: an input power supply; a parallel full-bridge LLC resonant circuit, adopting a frequency modulation method to convert the DC input voltage into a high DC output voltage, and the secondary side is full Wave rectification circuit structure; phase-shifted full bridge circuit, including a first branch and a second branch, the first branch is connected between any two bridge arms of the parallel full bridge LLC resonant circuit, and the adjustment method is adopted to adjust the The phase mode between the two bridge arms transforms the DC input voltage into the first low DC output voltage; the second branch is connected between the remaining two bridge arms of the parallel full-bridge LLC resonant circuit, and the The phase mode between the two bridge arms transforms the DC input voltage into the second lowest DC output voltage; the secondary side is a full-wave rectification circuit structure. The converter implements mutual isolation among the three outputs through two different control methods between the two bridge arms.

Description

A Hybrid Modulation Isolated Three-way Output DC-DC Converter

technical field

The invention belongs to the field of power electronics, and in particular relates to a hybrid modulation isolation type three-way output DC-DC converter.

Background technique

With the development of digital control technology, the power supply requirements for many new electrical equipment are getting higher and higher. Many electrical equipment require both high-voltage DC power supply and multi-channel low-voltage DC power supply for auxiliary systems and control systems during operation. powered by. If multiple input power sources are used for power supply, the size and cost of the system will be increased, which is not conducive to equipment integration. However, in the traditional multi-output circuit, several output voltages cannot be completely isolated and adjusted independently. When one of the output states fluctuates, it will have a greater impact on the other two outputs, which will seriously affect the overall stability of the system. .

N.Ali, T.H.Mehrdad and others proposed a multi-input multi-output DC in the title A Nonisolated Multiinput Multioutput DC-DC Boost Converter for Electric Vehicle Applications (IEEE Transactions on Power Electronics, 2015.30(4), pp 1818-1835) -DC converter, the converter can realize multiple multi-outputs, but the outputs of the converter are not isolated from each other, and interact with each other, it is difficult to meet the needs of current electrical equipment for multi-output converters requirements.

The patent application with the publication number CN1870408A discloses a multi-output DC-DC converter, including a transformer, a main rectifier circuit and an auxiliary rectifier circuit, a PWM control circuit, the output terminal of the secondary winding of the transformer and the input of the main rectifier circuit and the auxiliary rectifier circuit. The terminals are connected; there is also a chopper composed of the first and second switching tubes in series, and the PWM control circuit outputs pulses with duty ratios of D and 1-D to the control terminals of the first and second switching tubes respectively, so that the first, second switching tubes The cut-off time of the second switching tube is fixed, and there is also a resonant circuit composed of a resonant capacitor, a first resonant inductance, and a second resonant inductance connected in parallel to the primary winding of the transformer in series, the input end of the resonant circuit and the output end of the chopper Connected, the first resonant inductor and the resonant capacitor resonate to realize the quasi-zero current turn-off of the first and second switch tubes, and the second resonant inductor, the first resonant inductor Lr and the resonant capacitor resonate to realize the zero-voltage turn-on of the first and second switch tubes. This technical content can easily realize soft switching and improve efficiency, but it does not realize mutual independence and isolation between outputs of various channels.

Contents of the invention

In view of the above-mentioned technical problems existing in the prior art, the present invention proposes a hybrid modulation isolation type three-way output DC-DC converter. The converter realizes mutual isolation among the three outputs through two different control methods between the two bridge arms; the converter realizes a stable DC voltage output by controlling the output voltage; at the same time, the converter has a high-frequency transformer, The function of electrical isolation can be realized.

In order to realize the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

A hybrid modulation isolated three-way output DC-DC converter, comprising:

input power;

Parallel full-bridge LLC resonant circuit, using frequency modulation to convert the DC input voltage into a high DC output voltage, the secondary side is a full-wave rectifier circuit structure;

A phase-shifting full-bridge circuit, including a first branch and a second branch, the first branch is connected between any two bridge arms of the parallel full-bridge LLC resonant circuit, and the adjustment between the two bridge arms is adopted. The phase mode transforms the DC input voltage into the first low DC output voltage; the second branch is connected between the remaining two bridge arms of the parallel full-bridge LLC resonant circuit, and the adjustment between the two bridge arms is adopted. The phase mode converts the DC input voltage to the second lowest DC output voltage; the secondary side is a full-wave rectification circuit structure.

The DC-DC converter of the present invention has the advantages of electrical isolation, low cost, high efficiency, high power density, and mutual independence between different output voltages.

Preferably, the parallel full-bridge LLC resonant circuit includes:

The first bridge arm is connected in parallel with the input power supply and consists of a first power switch tube and a second power switch tube connected in series, the drain of the first power switch tube is connected to the positive pole of the input power supply, and the second power switch tube The source of is connected to the negative pole of the input power supply;

The second bridge arm is connected in parallel with the input power supply, and is composed of a third power switch tube and a fourth power switch tube connected in series, the drain of the third power switch tube is connected to the positive pole of the input power supply, and the fourth power switch tube The source of is connected to the negative pole of the input power supply;

The third bridge arm is connected in parallel with the input power supply, and is composed of a fifth power switch tube and a sixth power switch tube connected in series, the drain of the fifth power switch tube is connected to the positive pole of the input power supply, and the sixth power switch tube The source of is connected to the negative pole of the input power supply;

The fourth bridge arm is connected in parallel with the input power supply, and is composed of a seventh power switch tube and an eighth power switch tube connected in series, the drain of the seventh power switch tube is connected to the positive pole of the input power supply, and the eighth power switch tube The source of is connected to the negative pole of the input power supply;

The first resonant cavity is composed of the first resonant capacitor, the first resonant inductor and the primary winding of the first transformer connected in sequence, wherein the anode of the first resonant capacitor is connected to the source of the first power switch tube, and the first The opposite end of the primary winding of the transformer is connected to the source of the third power switch tube;

The second resonant cavity is composed of the second resonant capacitor, the second resonant inductor and the primary winding of the second transformer connected in sequence, wherein the anode of the second resonant capacitor is connected to the source of the fifth power switch tube, and the second The opposite end of the primary winding of the transformer is connected to the source of the seventh power switch tube;

The first power switch tube, the second power switch tube, the third power switch tube and the fourth power switch tube, the fifth power switch tube, the sixth power switch tube, the seventh power switch tube and the eighth power switch tube are all With anti-parallel diode.

In the present invention, compared with the traditional LLC resonant circuit, the two-way parallel LLC resonant cavity structure can reduce the resonant current of each resonant cavity, reduce the current stress of the device on each path, thereby reducing the volume and loss of the magnetic element, and improving the Converter efficiency.

Preferably, the secondary side of the parallel full-bridge LLC resonant circuit includes:

The first secondary winding of the first transformer, the second secondary winding of the first transformer, the opposite end of the first secondary winding is connected to the same end of the second secondary winding;

a first power diode, the anode of which is connected to the same-named end of the first secondary winding,

For a second power diode, the anode is connected to the opposite end of the second secondary winding, and the cathode is connected to the cathode of the first power diode;

The third secondary winding of the second transformer, the fourth secondary winding of the second transformer, the opposite end of the third secondary winding is connected to the same end of the fourth secondary winding;

a third power diode, the anode of which is connected to the same-named end of the third secondary winding,

For a fourth power diode, the anode is connected to the opposite end of the fourth secondary winding, and the cathode is connected to the cathode of the third power diode;

The first filter capacitor, the negative pole is connected to the opposite end of the first secondary winding, and the positive pole is connected to the cathode of the first power diode;

For the second filter capacitor, the negative pole is connected to the opposite terminal of the third secondary winding, and the positive pole is connected to the negative pole of the third power diode and the negative pole of the first filter capacitor at the same time;

The positive pole of the first filter capacitor and the negative pole of the second filter capacitor are used as high DC voltage output terminals of the DC-DC converter.

Preferably, the primary side of the phase-shifted full-bridge circuit includes:

The primary side of the first branch is composed of the first DC blocking capacitor and the primary winding of the third transformer connected in sequence, the positive pole of the first DC blocking capacitor is connected to the source of the first power switch tube, and the primary side of the third transformer The opposite end of the winding is connected to the source of the fifth power switch tube;

The primary side of the second branch is composed of the second DC blocking capacitor and the primary winding of the fourth transformer connected in sequence, the positive pole of the second DC blocking capacitor is connected to the source of the third power switch tube, and the primary side of the fourth transformer The opposite end of the winding is connected to the source of the seventh power switch tube.

Preferably, the secondary side of the phase-shifted full-bridge circuit includes:

The fifth secondary winding of the third transformer, the sixth secondary winding of the third transformer, the opposite end of the fifth secondary winding is connected to the same end of the sixth secondary winding;

The fifth power diode, the anode of which is connected to the terminal with the same name as the fifth secondary winding,

The sixth power diode, the anode is connected to the opposite end of the sixth secondary winding, and the cathode is connected to the cathode of the fifth power diode;

The first filter inductor, the anode of which is connected to the cathode of the fifth power diode, and the cathode of which is connected to the anode of the third filter capacitor;

The third filter capacitor, the positive pole is connected to the negative pole of the first filter inductor, and the negative pole is connected to the opposite end of the fifth secondary winding;

The positive pole and the negative pole of the third filter capacitor serve as the first low DC voltage output terminal of the DC-DC converter.

Preferably, the secondary side of the phase-shifted full-bridge circuit includes:

The seventh secondary winding of the fourth transformer, the eighth secondary winding of the fourth transformer, the opposite end of the seventh secondary winding is connected to the same end of the eighth secondary winding;

The seventh power diode, the anode of which is connected to the end of the seventh secondary winding with the same name,

An eighth power diode, the anode of which is connected to the opposite end of the eighth secondary winding, and the cathode connected to the cathode of the seventh power diode;

The second filter inductor, the anode of which is connected to the cathode of the seventh power diode, and the cathode of which is connected to the anode of the fourth filter capacitor;

The fourth filter capacitor, the positive pole is connected to the negative pole of the second filter inductor, and the negative pole is connected to the opposite end of the seventh secondary winding;

The positive and negative poles of the fourth filter capacitor serve as the second low DC voltage output terminal of the DC-DC converter.

Wherein, the first power switch tube, the second power switch tube, the third power switch tube, the fourth power switch tube, the fifth power switch tube, the sixth power switch tube, the seventh power switch tube and the eighth power switch tube The tubes are all power metal-oxide semiconductor field effect transistors.

The high DC voltage output terminal outputs a DC voltage of 200V-400V. The first low DC voltage output terminal outputs a DC voltage of 48V. The second low DC voltage output terminal outputs a DC voltage of 24V.

Wherein, the secondary side of the parallel full-bridge LLC resonant circuit may also be a full-bridge rectifier circuit structure.

Compared with prior art, the beneficial effect that the present invention has is:

(1) Compared with the traditional LLC resonant circuit, the two-way parallel LLC resonant cavity structure can reduce the resonant current of each resonant cavity, reduce the current stress of each circuit device, thereby reducing the volume and loss of magnetic components, and improving the conversion device efficiency.

(2) The output of the LLC resonant circuit and the two phase-shifted full-bridge outputs adopt different control methods to realize independent control of the three outputs and reduce the cross-regulation rate between the three outputs.

(3) The LLC resonant circuit adopts the resonant cavity parallel connection mode of input parallel connection and output series connection, which can better share the current between the two resonant cavities.

(4) The three outputs are isolated from each other and controlled independently of each other, which can meet the requirements of occasions such as different voltage levels; the switching tube on the primary side can realize zero-voltage soft switching, which can reduce the switching loss of the switching tube and improve the converter s efficiency.

Description of drawings

Fig. 1 is the structural representation of the hybrid modulation isolation type three-way output DC-DC converter provided by the present invention;

Fig. 2 is the operating waveform diagram of the hybrid modulation isolation type three-way output DC-DC converter provided by the present invention;

Fig. 3 is an equivalent circuit diagram when the DC-DC converter shown in Fig. 1 is in working mode 1;

Fig. 4 is an equivalent circuit diagram when the DC-DC converter shown in Fig. 1 is in working mode 2;

Fig. 5 is an equivalent circuit diagram when the DC-DC converter shown in Fig. 1 is in working mode 3;

FIG. 6 is an equivalent circuit diagram when the DC-DC converter shown in FIG. 1 is in working mode 4 .

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, and do not limit the protection scope of the present invention.

A hybrid modulation isolated three-way output DC-DC converter, including a parallel full-bridge LLC resonant circuit and two phase-shifted full-bridge circuits; the primary side of the full-bridge LLC resonant circuit is a full-bridge circuit structure, and the secondary side is a full-bridge circuit structure. Wave rectification circuit structure; the diodes used are all power diodes.

As shown in Figure 1, the primary circuit includes:

1) The first primary side branch connected in parallel with the input voltage V _in is composed of the first power switch S ₁ and the second power switch S ₂ ; the second primary side branch connected in parallel with the input voltage _Vin , It is composed of the third power switch tube S ₃ and the fourth power switch tube S ₄ ; the third primary side branch connected in parallel with the input voltage V _in is composed of the fifth power switch tube S ₅ and the sixth power switch tube S ₆ ; The fourth primary side branch connected in parallel with the input voltage V _in is composed of the seventh power switch S ₇ and the eighth power switch S ₈ . Among them, the first power switch S ₁ , the second power switch S ₂ , the third power switch S ₃ , the fourth power switch S ₄ , the fifth power switch S ₅ , the sixth power switch S ₆ , Both the seventh power switch tube _S7 and the eighth power switch tube _S8 are power metal-oxide semiconductor field effect transistors (MOSFETs).

2) The first resonant cavity of the LLC resonant circuit is composed of resonant capacitor C _r1 , resonant inductance L _r1 and transformer T ₁ (transformer T ₁ is equivalent to composed of excitation inductance L _m1 and ideal transformer), and the first primary side branch It is connected with the second primary side branch. The resonant capacitor C _r1 and the resonant inductance L _r1 are connected in series, one end of the resonant capacitor C _r1 is connected to the source of the first power switch S ₁ on the first primary side branch, and one end of the resonant inductance L _r1 is connected to the primary winding of the transformer T ₁ The terminal with the same name is connected, and the terminal with the same name of the primary winding of the transformer is connected with the source of the third power switch _S3 on the second primary branch.

3) The second resonant cavity of the LLC resonant circuit is composed of resonant capacitor C _r2 , resonant inductance L _r2 and transformer T ₂ (transformer T ₂ is equivalent to composed of excitation inductance L _m2 and ideal transformer), and the third primary side branch It is connected with the fourth primary side branch. The resonant capacitor C _r2 is connected in series with the resonant inductance L _r2 , one end of the resonant capacitor C _r2 is connected to the source of the fifth power switch _S5 on the third primary side branch, and one end of the resonant inductance L _r2 is connected to the primary winding of the transformer _T2 The terminal with the same name is connected, and the terminal with the same name of the primary winding of the transformer is connected with the source of the seventh power switch _S7 on the fourth primary branch.

By adjusting the first power switch S 1 , the second power switch S ₂ , the third power switch S ₃ , and the fourth power switch on the first bridge arm _, the second bridge arm, the third bridge arm and the fourth bridge arm Switching frequency of tube S ₄ , fifth power switch tube S ₅ , sixth power switch tube S ₆ , seventh power switch tube S ₇ and eighth power switch tube S ₈ , and then change the gain of the resonant network to adjust the output voltage V _out1 in order to obtain the required voltage value.

4) The first transformer branch of the phase-shifted full-bridge circuit is composed of a DC blocking capacitor C _B1 and a transformer T ₃ (the transformer T ₃ is equivalent to a leakage inductance L _r3 as a resonant inductance and an ideal transformer), and is connected to the first primary side The branch is connected to the third primary side branch. The DC blocking capacitor C _B1 is connected in series with the primary winding of the transformer _T3 , one end of the DC blocking capacitor C _B1 is connected to the source of the first power switch _S1 on the first primary side branch, and the other end of the DC blocking capacitor C _B1 is connected to the transformer The same-name end of the primary winding of T ₃ is connected, and the opposite-name end of the primary winding of the transformer T ₃ is connected to the source of the fifth power switch S ₅ on the third primary branch.

5) The second transformer branch of the phase-shifted full-bridge circuit is composed of DC blocking capacitor C _B2 and transformer T ₄ (transformer T ₄ is equivalent to being composed of leakage inductance L _r4 as a resonant inductance and an ideal transformer), and is connected to the second primary side The branch is connected to the fourth primary side branch. The DC blocking capacitor C _B2 is connected in series with the primary winding of the transformer _T4 , one end of the DC blocking capacitor C _B2 is connected to the source of the third power switch _S3 on the second primary side branch, and the other end of the DC blocking capacitor C _B2 is connected to the transformer The same-name end of the primary winding of T ₄ is connected, and the opposite-name end of the primary winding of the transformer T ₄ is connected to the source of the seventh power switch S ₇ on the fourth primary branch.

By adjusting the phase between the first bridge arm and the third bridge arm, the output voltage V _out2 is adjusted; by adjusting the phase between the second bridge arm and the fourth bridge arm, the output voltage V _out3 is adjusted.

The secondary circuit includes:

1) The output branch of the secondary side of the parallel LLC resonant circuit consists of the first power diode D _o1 , the second power diode D _o2 , the third power diode D _o3 , the fourth power diode D _o4 , the first output filter capacitor C _o1 , the second power diode Two output filter capacitors C _o2 , two secondary windings of the isolation transformer T ₁ and two secondary windings of the isolation transformer T ₂ ; where the terminal with the same name of the first secondary winding of the isolation transformer T ₁ is connected to the first power diode D _o1 The anode of the first secondary winding is connected to the same name end of the second secondary winding of the isolation transformer _T1 , and is connected to the negative pole of the first output filter capacitor C _o1 ; the opposite name end of the second secondary winding is connected to _The anode of the second power diode D _o2 is connected, the cathode of the second power diode D _o2 is connected with the cathode of the first power diode D _o1 , and connected to the positive pole of the first output filter capacitor C _o1 ; The same-name end of the three secondary windings is connected to the anode of the third power diode D _o3 , and the same-name end of the third secondary winding is connected to the same-name end of the fourth secondary winding of the isolation transformer _T2 , and connected to the second output filter capacitor C _o2 The negative pole of the fourth secondary winding is connected to the anode of the fourth power diode D _o4 , the cathode of the fourth power diode D _o4 is connected to the cathode of the third power diode D _o3 , and connected to the second output filter capacitor Positive pole of C _o2 .

2) The secondary output branch of the first phase-shifted full bridge circuit consists of the fifth power diode D _o5 , the sixth power diode D _o6 , the first output filter inductor L _f1 , the third output filter capacitor C _o3 and the isolation transformer T ₃ composed of two secondary windings. Among them, the same-named end of the fifth secondary winding of the isolation transformer _T3 is connected to the anode of the fifth power diode D _o5 , and its different-named end is connected to the same-named end of the sixth secondary winding of the isolation transformer _T3 , and connected to the third output filter The negative pole of the capacitor C _o3 ; the opposite end of the sixth secondary winding _{of the isolation transformer T3 is connected to the anode of the sixth power diode D o6, the cathode of the sixth power diode D o6 is connected} to the cathode of the fifth power diode D _o5 , and connected to one end of the first output filter inductor L _f1 ; the other end of the first output filter inductor L _f1 is connected to the positive pole of the third output capacitor C _o3 .

3) The secondary output branch of the second phase-shifting full-bridge circuit consists of the seventh power diode D _o7 , the eighth power diode D _o8 , the second output filter inductor L _f2 , the fourth output filter capacitor C _o4 and the isolation transformer T ₄ composed of two secondary windings. Wherein, the same-named end of the seventh secondary winding of the isolation transformer _T4 is connected to the anode of the seventh power diode D _o7 , and its opposite-named end is connected to the same-named end of the eighth secondary winding of the isolation transformer _T4 , and connected to the fourth output filter The negative pole of the capacitor C _o4 ; the opposite end of the eighth secondary winding of the isolation transformer _T4 is connected to the anode of the eighth power diode D _o8 , the cathode of the eighth power diode D _o8 is connected to the cathode of the seventh power diode D _o7 , and connected to one end of the second output filter inductor L _f2 ; the other end of the second output filter inductor L _f2 is connected to the positive pole of the fourth output capacitor C _o4 .

4) Output load: the output loads are loads R _L1 , R _L2 , and R _L3 , and the loads R _L1 , R _L2 , and R _L3 are connected across the positive and negative ends of the output port.

Compared with the traditional multi-output parallel LLC resonant circuit and phase-shifted full-bridge circuit DC-DC converter, this embodiment realizes mutual independence and isolation between outputs of each channel. Among them, the full-bridge parallel LLC resonant circuit adjusts the voltage by adjusting the frequency, and the design outputs a DC voltage of 200V to 400V, which is called the high-voltage side; the voltage is adjusted by adjusting the phase of the first phase-shifting full-bridge circuit, and the output is designed to be 48V The DC voltage is called the first low-voltage side; the voltage is adjusted by adjusting the phase of the second phase-shifting full-bridge circuit, and the output DC voltage of 24V is designed to be called the second low-voltage side.

In order to describe the working mode commutation process, the following assumptions are made:

(1) In order to simplify the analysis, the resonant inductance L _r1 = L _r2 , the resonant capacitor C _r1 = C _r2 , and the excitation inductance L _m1 = L _m2 in the two-way parallel LLC resonant circuit;

(2) In order to simplify the analysis, in the analysis, the dead time of the two switching tubes on the same bridge arm is ignored;

(3) The upper and lower switching tubes on the first primary side branch, the second primary side branch, the third primary side branch and the fourth primary side branch work in a complementary state, and the duty cycle of each switching tube is turned on is 0.5.

(4) The phase shift between the first primary branch and the third primary branch is greater than 0° and less than 180°; the phase shift between the second primary branch and the fourth primary branch is greater than 0° , less than 180°.

Analysis of commutation process (ignoring dead time):

1) Mode 1: [t ₀ ～t ₁ ]

As shown in Figure 3, the switches S ₁ and S ₄ are turned on, the switches S ₂ and S ₃ are turned off, the switches S ₅ and S ₈ are turned off, the switches S ₆ and S ₇ are turned on, and the resonant inductance L _r1 Resonance occurs with the resonant capacitor C _r1 , the resonant current i _Lr1 lags behind the input voltage, the switch tubes S ₁ and S ₄ are softly turned on at zero voltage, the resonant current i _Lr1 changes in a sinusoidal form, and the difference between the resonant current i _Lr1 and the excitation inductor current i _Lm1 is transmitted to the secondary side; the resonant inductance L _r2 and the resonant capacitor C _r2 resonate, the resonant current i _Lr2 changes in a sinusoidal form, and the difference between the excitation inductance current i _Lm2 and the resonant current i _Lr2 is transmitted to the secondary side; the first phase-shifted full bridge When the input voltage v _AC is +V _in , the current i _Lr3 increases linearly; when the input voltage v _BD of the second phase-shifted full bridge is -V _in , the current i _Lr4 decreases linearly.

2) Mode 2: [t ₁ ～t ₂ ]

As shown in Figure 4, the switches S ₁ and S ₄ are turned on, the switches S ₂ and S ₃ are turned off, the switches S ₅ and S ₈ are turned on, the switches S ₆ and S ₇ are turned off, and the resonant inductance L _r1 Resonance occurs with the resonant capacitor C _r1 , and the resonant current i _Lr1 changes in a sinusoidal form, and the difference between the resonant current i _Lr1 and the excitation inductance current i _Lm1 is transmitted to the secondary side; the resonant inductance L _r2 and the resonant capacitor C _r2 resonate, and the resonant current i _Lr2 The input voltage lags behind, the switch tubes S ₅ and S ₈ are softly turned on at zero voltage, the resonant current i _Lr2 changes in a sinusoidal form, and the difference between the resonant current i _Lr2 and the excitation inductance current i _Lm2 is transmitted to the secondary side; the first phase-shifted full bridge The input voltage v _AC is 0, and the secondary diodes D _o5 and D _o6 are turned on at the same time, so that the voltage of the secondary winding of the transformer _T3 is 0, and the voltage of the primary winding is also 0, the leakage inductance L _r3 of the transformer _T3 Working with the DC blocking capacitor C _B1 in a resonant state; similarly, the input voltage v _BD of the second phase-shifted full bridge is 0, and at this time the secondary side diodes D _o7 and D _o8 are turned on at the same time, so that the secondary side of the transformer T ₄ The winding voltage is 0, the primary winding voltage is 0 accordingly, the leakage inductance L _r4 of the transformer T ₄ and the DC blocking capacitor C _B2 work in a resonance state.

3) Mode 3: [t ₂ ～t ₃ ]

As shown in Figure 5, the switches S ₁ and S ₄ are turned off, the switches S ₂ and S ₃ are turned on, the switches S ₅ and S ₈ are turned on, the switches S ₆ and S ₇ are turned off, and the resonant inductance L _r1 Resonance occurs with the resonant capacitor C _r1 , the resonant current i _Lr1 lags behind the input voltage, the switches S ₂ and S ₃ are softly turned on with zero voltage, the resonant current i _Lr1 changes in a sinusoidal form, and the difference between the excitation inductor current i _Lm1 and the resonant current i _Lr1 is transmitted to the secondary side; the resonant inductance L _r2 and the resonant capacitor C _r2 resonate, the resonant current i _Lr2 changes in a sinusoidal form, and the difference between the resonant current i _Lr2 and the exciting inductor current i _Lm2 is transmitted to the secondary side; the first phase-shifted full-bridge circuit The input voltage is -V _in , the current i _Lr3 decreases linearly; the input voltage of the second phase-shifted full bridge circuit is +V _in , and the current i _Lr4 increases linearly.

4) Mode 4: [t ₃ ～t ₄ ]

As shown in Figure 6, the switches S ₁ and S ₄ are turned off, the switches S ₂ and S ₃ are turned on, the switches S ₅ and S ₈ are turned off, the switches S ₆ and S ₇ are turned on, and the resonant inductance L _r1 It resonates with the resonant capacitor C _r1 , and the resonant current i _Lr1 changes in a sinusoidal form, and the difference between the excitation inductor current i _Lm1 and the resonant current i _Lr1 is transmitted to the secondary side; the resonant inductance L _r2 resonates with the resonant capacitor C _r2 , and the resonant current i _Lr2 The input voltage lags behind, the switch tubes S ₆ and S ₇ are softly turned on at zero voltage, the resonant current i _Lr2 changes in a sinusoidal form, and the difference between the excitation inductance current i _Lm2 and the resonant current i _Lr2 is transmitted to the secondary side; the first phase-shifted full bridge The input voltage v _AC is 0, and the secondary diodes D _o5 and D _o6 are turned on at the same time, so that the voltage of the secondary winding of the transformer _T3 is 0, and the voltage of the primary winding is also 0, the leakage inductance L _r3 of the transformer _T3 Working with the DC blocking capacitor C _B1 in a resonant state; similarly, the input voltage v _BD of the second phase-shifted full bridge is 0, and at this time the secondary side diodes D _o7 and D _o8 are turned on at the same time, so that the secondary side of the transformer T ₄ The winding voltage is 0, the primary winding voltage is 0 accordingly, the leakage inductance L _r4 of the transformer T ₄ and the DC blocking capacitor C _B2 work in a resonance state.

The above-mentioned specific embodiments have described the technical solutions and beneficial effects of the present invention in detail. It should be understood that the above-mentioned are only the most preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, supplements and equivalent replacements made within the scope shall be included in the protection scope of the present invention.

Claims (10)

1. a kind of three road output DC-DC converter of hybrid modulation isolated form, which is characterized in that including：

Input power；

DC input voitage is transformed to high DC output voltage by full-bridge LLC resonance circuits in parallel using frequency modulated mode, secondary Side is full-wave rectifying circuit structure；

Phase whole-bridging circuit, including the first branch and the second branch, the first branch are connected to the full-bridge LLC resonance in parallel Between any two bridge arm of circuit, DC input voitage is transformed to first using the phase mode adjusted between two bridge arms Low DC output voltage；The second branch is connected between remaining two bridge arms of the full-bridge LLC resonance circuits in parallel, is adopted DC input voitage is transformed to the second low DC output voltage with the phase mode adjusted between two bridge arms；Secondary side is all-wave Rectifier circuit structure.

2. three road output DC-DC converter of hybrid modulation isolated form as described in claim 1, which is characterized in that the parallel connection Full-bridge LLC resonance circuits include：

First bridge arm, it is in parallel with the input power, it is made of concatenated first power switch tube and the second power switch tube, the The drain electrode of one power switch tube is connected with the anode of the input power, the source electrode of the second power switch tube and the input power Cathode be connected；

Second bridge arm, it is in parallel with the input power, it is made of concatenated third power switch tube and the 4th power switch tube, the The drain electrode of three power switch tubes is connected with the anode of the input power, source electrode and the input power of the 4th power switch tube Cathode be connected；

Third bridge arm, it is in parallel with the input power, it is made of concatenated 5th power switch tube and the 6th power switch tube, the The drain electrode of five power switch tubes is connected with the anode of the input power, source electrode and the input power of the 6th power switch tube Cathode be connected；

Four bridge legs, it is in parallel with the input power, it is made of concatenated 7th power switch tube and the 8th power switch tube, the The drain electrode of seven power switch tubes is connected with the anode of the input power, source electrode and the input power of the 8th power switch tube Cathode be connected；

First resonant cavity, by sequentially connected first resonant capacitance, the first resonant inductance and the first transformer primary side winding group At, wherein the anode of the first resonant capacitance is connected with the source electrode of first power switch tube, the first transformer primary side winding Different name end is connected with the source electrode of the third power switch tube；

Second resonant cavity, by sequentially connected second resonant capacitance, the second resonant inductance and the second transformer primary side winding group At, wherein the anode of the second resonant capacitance is connected with the source electrode of the 5th power switch tube, the second transformer primary side winding Different name end is connected with the source electrode of the 7th power switch tube；

First power switch tube, the second power switch tube, third power switch tube and the 4th power switch tube, the 5th power Switching tube, the 6th power switch tube, the 7th power switch tube and the 8th power switch tube carry anti-and diode.

3. three road output DC-DC converter of hybrid modulation isolated form as claimed in claim 2, which is characterized in that the parallel connection The secondary side of full-bridge LLC resonance circuits includes：

First vice-side winding of the first transformer, the second vice-side winding of the first transformer, the different name of first vice-side winding End is connected with the Same Name of Ends of the second vice-side winding；

First power diode, anode are connected with the Same Name of Ends of first vice-side winding,

Second power diode, anode are connected with the different name end of second vice-side winding, cathode and two pole of the first power The cathode of pipe is connected；

The third vice-side winding of second transformer, the 4th vice-side winding of the second transformer, the different name of the third vice-side winding End is connected with the Same Name of Ends of the 4th vice-side winding；

Third power diode, anode are connected with the Same Name of Ends of the third vice-side winding,

4th power diode, anode are connected with the different name end of the 4th vice-side winding, cathode and two pole of third power The cathode of pipe is connected；

First filter capacitor, cathode are connected with the different name end of first vice-side winding, positive and first power diode Cathode be connected；

Second filter capacitor, cathode are connected with the different name end of the third vice-side winding, anode simultaneously with the third power two The cathode of pole pipe is connected with the cathode of first filter capacitor；

High Level DC Voltage of the anode of first filter capacitor with the cathode of second filter capacitor as DC-DC converter Output end.

4. three road output DC-DC converter of hybrid modulation isolated form as claimed in claim 3, which is characterized in that the phase shift The primary side of full-bridge circuit includes：

First branch primary side is made of, the first capacitance sequentially connected first capacitance, third transformer primary side winding Anode be connected with the source electrode of first power switch tube, the different name end of third transformer primary side winding and the 5th power The source electrode of switching tube is connected；

The second branch primary side is made of, the second capacitance sequentially connected second capacitance, the 4th transformer primary side winding Anode be connected with the source electrode of the third power switch tube, the different name end of the 4th transformer primary side winding and the 7th power The source electrode of switching tube is connected.

5. three road output DC-DC converter of hybrid modulation isolated form as claimed in claim 4, which is characterized in that the phase shift The secondary side of full-bridge circuit includes：

5th vice-side winding of third transformer, the 6th vice-side winding of third transformer, the different name of the 5th vice-side winding End is connected with the Same Name of Ends of the 6th vice-side winding；

5th power diode, anode are connected with the Same Name of Ends of the 5th vice-side winding,

6th power diode, anode are connected with the different name end of the 6th vice-side winding, cathode and two pole of the 5th power The cathode of pipe is connected；

First filter inductance, the positive cathode with the 5th power diode are connected, the anode of cathode and third filter capacitor It is connected；

Third filter capacitor, the positive cathode with first filter inductance are connected, and cathode is different with the 5th vice-side winding Name end is connected；

First low dc voltage output end of the positive electrode and negative electrode of the third filter capacitor as DC-DC converter.

6. three road output DC-DC converter of hybrid modulation isolated form as claimed in claim 5, which is characterized in that the phase shift The secondary side of full-bridge circuit includes：

7th vice-side winding of the 4th transformer, the 8th vice-side winding of the 4th transformer, the different name of the 7th vice-side winding End is connected with the Same Name of Ends of the 8th vice-side winding；

7th power diode, anode are connected with the Same Name of Ends of the 7th vice-side winding,

8th power diode, anode are connected with the different name end of the 8th vice-side winding, cathode and two pole of the 7th power The cathode of pipe is connected；

Second filter inductance, the positive cathode with the 7th power diode are connected, the anode of cathode and the 4th filter capacitor It is connected；

4th filter capacitor, the positive cathode with second filter inductance are connected, and cathode is different with the 7th vice-side winding Name end is connected；

Second low dc voltage output end of the positive electrode and negative electrode of 4th filter capacitor as DC-DC converter.

7. three road output DC-DC converter of hybrid modulation isolated form as claimed in claim 2, which is characterized in that described first Power switch tube, the second power switch tube, third power switch tube, the 4th power switch tube, the 5th power switch tube, the 6th work( Rate switching tube, the 7th power switch tube and the 8th power switch tube are power metal-oxide semiconductor field effect transistor.

8. such as three road output DC-DC converter of claim 1~7 any one of them hybrid modulation isolated form, which is characterized in that The DC voltage of the High Level DC Voltage output end output 200V~400V.

9. such as three road output DC-DC converter of claim 1~7 any one of them hybrid modulation isolated form, which is characterized in that The DC voltage of the first low dc voltage output end output 48V.

10. such as three road output DC-DC converter of claim 1~7 any one of them hybrid modulation isolated form, feature exists In the DC voltage of the second low dc voltage output end output 24V.