CN203674977U - Multiphase dc-dc converter - Google Patents

Abstract

The utility model discloses a multi-phase DC-DC converter, which comprises: an input terminal for receiving a DC input voltage; a plurality of single-phase DC-DC converters connected in parallel for converting the DC input voltage into DC-DC transformation; an output terminal for outputting the DC output voltage transformed by the plurality of single-phase DC-DC converters; and an equalization circuit connected in series with the plurality of single-phase DC-DC converters connected in parallel in multi-phase Between the input terminal and the output terminal of the DC-DC converter, it is used to balance the current of the multiple single-phase DC-DC converters.

Description

Multiphase DC-DC Converter

technical field

The utility model generally relates to the field of converters, and more specifically relates to a DC-DC converter with a multi-phase structure.

Background technique

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

Various types of direct current-direct current (DC-DC) converters are known. For example, multiphase DC-DC converters are known which employ two or more independent single-phase DC-DC converters connected in parallel. For example, in a multiphase DC-DC converter employing two single-phase DC-DC converters, the output currents of the two single-phase DC-DC converters are shifted in phase by 90°. This results in a current overlapping current at the output of the multiphase DC-DC converter, thereby reducing the ripple current in the output capacitor. Additionally, the resonant components must be well matched to achieve acceptable current sharing between the two single-phase converters. Otherwise, the ripple current in the output capacitor will be higher. Therefore, it is necessary to improve the existing multi-phase DC-DC converter.

Utility model content

In view of the above circumstances of the prior art, an object of this utility model is to provide an equalizing circuit to improve the multiphase DC-DC converter, which can at least realize the acceptable current sharing.

According to one aspect of the present utility model, a multi-phase DC-DC converter is provided, including: an input terminal for receiving a DC input voltage; a plurality of single-phase DC-DC converters connected in parallel for converting the The DC input voltage is converted to DC-DC; the output terminal is used to output the DC output voltage transformed by the multiple single-phase DC-DC converters; and the equalization circuit is connected to the multiple single-phase DC-DC in parallel The converters are connected in series between the input terminal and the output terminal, and are used to balance the current of the multiple single-phase DC-DC converters.

According to another aspect of the present invention, the multi-phase DC-DC converter may further include a drive circuit for driving the multiple single-phase DC-DC converters, so that the multiple single-phase DC-DC The phases of the output currents of the converters have a predetermined phase shift with respect to each other.

According to another aspect of the present utility model, wherein, the equalization circuit is composed of differential mode inductors.

According to another aspect of the present utility model, wherein, the output terminal of the multi-phase DC-DC converter may include a first output terminal and a second output terminal, and the first coil of the differential mode inductor is connected in series to the multi-phase DC-DC converter. Between the first common output terminal of a single-phase DC-DC converter and the first output terminal, the second coil of the differential mode inductor is connected in series to the second of the plurality of single-phase DC-DC converters between the common output terminal and the second output terminal.

According to another aspect of the present utility model, wherein, the input terminal of the multiphase DC-DC converter may include a first input terminal and a second input terminal, and the first coil of the differential mode inductor is connected in series with the first input terminal. Between an input end and the first common input end of the plurality of single-phase DC-DC converters, the second coil of the differential mode inductor is connected in series between the second input end and the plurality of single-phase DC - between the second common input terminals of the DC converter.

According to another aspect of the present invention, the equalization circuit may be composed of differential mode inductors. Wherein, the output terminal of the multi-phase DC-DC converter includes a first output terminal and a second output terminal, and the first coil of the differential mode inductor is connected in series with the first coil of the plurality of single-phase DC-DC converters. Between a common output terminal and the first output terminal, the second coil of the differential mode inductor is connected in series between the second common output terminal of the plurality of single-phase DC-DC converters and the second output terminal between.

According to another aspect of the present utility model, each of the plurality of single-phase DC-DC transformers may include: a main transformer for transforming the DC input voltage; a switch unit including a plurality of switches an element provided between the input terminal of the single-phase DC-DC converter and the primary side of the main transformer, for switching the DC input voltage by turning on and off operations of the plurality of switching elements provided to the primary side of the main transformer; and a rectifier connected between the secondary side of the main transformer and the output terminal of the single-phase DC-DC converter for supplying the secondary side of the main transformer The output voltage is rectified to output the DC output voltage, wherein the rectifier is a full-bridge rectifier or a half-bridge rectifier.

According to another aspect of the present invention, the rectifier may be a half-bridge rectifier, and the half-bridge rectifiers of the plurality of single-phase DC-DC transformers may have a common capacitor bridge arm.

According to another aspect of the present invention, wherein the rectifier may be a half-bridge rectifier, and the balancing circuit may be connected in series between the diode bridge arm and the capacitor bridge arm of the half-bridge rectifier.

According to another aspect of the present invention, wherein, the switch unit may include two or four switch elements connected in a bridge.

According to another aspect of the present invention, the multi-phase DC-DC converter may further include at least one DC-DC converter connected in parallel between the plurality of single-phase DC-DC converters and the equalization circuit and the output terminal The filter capacitor is used for filtering ripples in the output voltages of the multiple single-phase DC-DC converters.

According to another aspect of the present utility model, wherein, in each single-phase DC-DC converter, the driving signal of each switching element in the switching unit may have a duty cycle of about 50%, and the switching unit There may be a phase shift of 180 degrees between the driving signal of the first switching element and the driving signal of the second switching element, and when the first switching element is turned on, the primary side coil of the main transformer passes through the first direction input current, and when the second switch element is turned on, the primary side coil of the main transformer passes an input current in a second direction opposite to the first direction.

According to another aspect of the present utility model, wherein, the predetermined phase shift may be 180°/n, where n is the number of the plurality of single-phase DC-DC converters.

In the multiphase DC-DC converter according to the above aspect of the present invention, the balancing circuit is connected in series with a plurality of single-phase DC-DC converters connected in parallel between the input terminal and the output terminal of the multiphase DC-DC converter. It can balance the current of multiple single-phase DC-DC converters in the multi-phase DC-DC converter, and reduce the difference between the input current or output current of multiple single-phase DC-DC converters, so as to realize multiple Acceptable current sharing between multiple single-phase converters in a phase DC-DC converter.

Description of drawings

The present invention can be better understood by referring to the following description given in conjunction with the accompanying drawings, wherein the same or similar reference numerals are used throughout the drawings to denote the same or similar components. The accompanying drawings, together with the following detailed description, are included in and form a part of this specification, and are used to further illustrate preferred embodiments of the utility model and explain principles and advantages of the utility model. In the attached picture:

Fig. 1 shows a schematic block diagram of a multiphase DC-DC converter according to a first embodiment of the present invention;

2A and 2B show an example circuit diagram of an equalization circuit in a multiphase DC-DC converter according to a first embodiment of the present invention;

FIG. 3 shows an example circuit diagram of a multiphase DC-DC converter according to a first embodiment of the present invention;

4-5 illustrate example waveform diagrams of currents and voltages of the multiphase DC-DC converter of FIG. 3;

Fig. 6 shows another example circuit diagram of the multiphase DC-DC converter according to the first embodiment of the present invention;

Fig. 7 shows another example circuit diagram of the multi-phase DC-DC converter according to the first embodiment of the present invention;

Fig. 8 shows another example circuit diagram of the multiphase DC-DC converter according to the first embodiment of the present invention;

Fig. 9 shows another example circuit diagram of the multi-phase DC-DC converter according to the first embodiment of the present invention;

Fig. 10 shows a schematic block diagram of a multiphase DC-DC converter according to a second embodiment of the present invention;

11A and 11B show an example circuit diagram of an equalization circuit in a multiphase DC-DC converter according to a second embodiment of the present invention;

Fig. 12 shows an example circuit diagram of a multiphase DC-DC converter according to a second embodiment of the present invention;

Fig. 13 shows another example circuit diagram of the multiphase DC-DC converter according to the second embodiment of the present invention;

Fig. 14 shows another example circuit diagram of the equalization circuit in the multiphase DC-DC converter according to the second embodiment of the present invention; and

Fig. 15 shows another example circuit diagram of the multi-phase DC-DC converter according to the second embodiment of the present invention.

Detailed ways

Embodiments of the present utility model will be described below with reference to the accompanying drawings. Elements and features described in one drawing or one embodiment of the present invention may be combined with elements and features shown in one or more other drawings or embodiments. It should be noted that, for the sake of clarity, representation and description of components and processes that are not relevant to the present invention and known to those of ordinary skill in the art are omitted from the drawings and descriptions.

In an embodiment of the present invention, a plurality of single-phase DC-DC converters connected in parallel are used to equalize a plurality of single-phase The current of the DC-DC converter reduces the difference between the currents of multiple single-phase DC-DC converters, thereby achieving an acceptable current between multiple single-phase converters in a multi-phase DC-DC converter shared. As an example and not a limitation, an equalization circuit may be provided between a plurality of single-phase DC-DC converters connected in parallel and input terminals of a multi-phase DC-DC converter, for equalizing the input terminals of the plurality of single-phase DC-DC converters Input current; or, it can also be set between multiple single-phase DC-DC converters connected in parallel and the output terminals of multi-phase DC-DC converters to balance the output current of multiple single-phase DC-DC converters .

In the embodiments of the present utility model, for the sake of distinction, the multiphase DC-DC converter can also be called a multiphase DC-DC conversion system, and the multiple single-phase DC-DC converters in the multiphase DC-DC converter It can also be referred to as a DC-DC converter for short.

Fig. 1 shows a schematic block diagram of a multiphase DC-DC converter according to a first embodiment of the present invention. In the first embodiment of the present utility model, the equalization circuit is arranged between a plurality of single-phase DC-DC converters connected in parallel and the output ends of the multi-phase DC-DC converters, and is used to equalize a plurality of single-phase DC-DC converters. The output current of the DC converter. As shown in Fig. 1, the multiphase DC-DC converter 100 includes: input terminals (131, 132) for receiving a DC input voltage Vin; a plurality of single-phase DC-DC converters (111, 112, ... , 11n), used to convert the DC input voltage Vin to DC-DC, where n is a positive integer greater than 1; the output terminal (133, 134) is used to output the DC converted by multiple single-phase DC-DC converters an output voltage Vout; and an equalizing circuit (120), connected in series with a plurality of single-phase DC-DC converters (111, 112, ..., 11n) connected in parallel, and provided at the plurality of single-phase DC-DC converters (111 , 112,..., 11n) and the output terminals (133, 134), used to balance the output current of the multiple single-phase DC-DC converters.

The input terminals ( 131 , 132 ) generally include a first input terminal and a second input terminal, respectively connected to a ground potential and a high potential higher than the ground, and the difference between the high potential and the ground potential is the value of the input voltage Vin. Similarly, the output terminals ( 133 , 134 ) usually include a first output terminal and a second output terminal, respectively connected to a ground potential and a high potential higher than the ground, and the difference between the high potential and the ground potential is the value of the output voltage Vout. For the convenience of description below, the input end 131 is called the first input end, the input end 132 is called the second input end; the output end 133 is called the first output end, and the output end 134 is called the second output end. However, it should be understood that "first" and "second" used here and below are only for distinction and not for limitation.

In this embodiment, the DC-DC converters (111, 112, ..., 11n) can be realized by using various single-phase DC-DC converters with appropriate structures, such as forward converters, bridge converters, push-pull type converter, etc., without limitation.

In this embodiment, the equalization circuit 120 can be implemented by using an equalization circuit with an appropriate structure. For example, the equalization circuit 120 may be implemented using a differential mode inductor or an LC circuit composed of an inductor and a capacitor.

The multi-phase DC-DC converter 100 also includes a drive circuit (not shown) for driving the multiple single-phase DC-DC converters (111, 112, ..., 11n), so that the multiple The phases of the output currents of the single-phase DC-DC converter have a predetermined phase shift from each other. Preferably, the predetermined phase shift may be 180°/n, where n is the number of the plurality of single-phase DC-DC converters. Such a predetermined phase shift can better eliminate the ripple in the output current of the multiphase DC-DC converter, so the output capacitance in the multiphase DC-DC converter can be reduced or omitted. Any suitable configuration of drive circuits may be used here. In order not to obscure the present invention, the structure of the driving circuit will not be described in detail here and below.

FIG. 2A shows an example circuit diagram of an equalization circuit in a multiphase DC-DC converter according to a first embodiment of the present invention. In this example, the multiphase DC-DC converter 200 implements a balancing circuit using a differential mode inductor 220 . As shown in Figure 2, the first coil of the differential mode inductor 220 is connected in series with the first common output end 243 of multiple single-phase DC-DC converters (211, 212, ..., 21n) and the multi-phase DC-DC converter Between the first output terminals 233 of the differential mode inductor 220, the second coil of the differential mode inductor 220 is connected in series to the second common output terminal 244 of a plurality of single-phase DC-DC converters (211, 212, ..., 21n) and the multi-phase DC- between the second output terminals 234 of the DC converter. The first common output terminal 243 and the second common output terminal 244 are respectively connected to the same-named end of one coil of the differential mode inductor 220 and the non-identical end of the other coil. In this way, the direction of the current flowing into the two coils of the differential mode inductor is opposite, and the magnetic flux generated by the initial current in each coil induces in the other coil an induction current opposite to the direction of the initial current in the other coil. Thereby, the difference of the currents flowing in the two coils is reduced, thereby reducing the difference of the output currents of the multiple single-phase DC-DC converters ( 211 , 212 , . . . , 21n).

In this example, the dotted ends of the two coils of the differential mode inductor (represented by the black dots in the diagram) are on one side. In other examples, the terminals with the same name of the two coils of the differential mode inductor can also be on opposite sides, and the first common output terminal 243 and the second common output terminal 244 can still be respectively connected to the terminals of the same name of a coil of the differential mode inductor 220. terminal and the non-identical terminal of another coil, as shown in Figure 2B.

In the present disclosure, the differential mode inductor is defined functionally, which inhibits the differential mode voltage and current signals, and its structure can use common mode or differential mode inductors with the same terminal on one side or different terminals on different sides.

Fig. 3 shows an example circuit diagram of a multi-phase DC-DC converter according to a first embodiment of the present invention. As shown in FIG. 3 , the multiphase DC-DC converter 300 includes two single-phase DC-DC converters 311 and 312 connected in parallel. The DC-DC converter 311 is shown by a dotted line box in the figure, and the DC-DC converter 312 is shown by a two-dot dash line box in the figure. The equalization circuit is realized by the differential mode inductor T3.

The DC-DC converter 311 includes: a main transformer T1 for transforming the DC input voltage Vin provided by the DC power supply at the input terminals (331, 332) of the DC-DC converter 311; a switch unit including multiple switching elements (Q1, Q2), provided between the input terminal of the DC-DC converter 311 and the primary side of the main transformer T1, for switching the DC input through the on and off operations of the plurality of switching elements a voltage supplied to the primary side of the main transformer; and a rectifier, connected between the secondary side of the main transformer and the output terminal of the DC-DC converter 311, for rectifying the voltage output from the secondary side of the main transformer, to output a DC output voltage.

The switches Q1 and Q2 in the DC-DC converter 311 are connected in a half bridge to form a switching unit. Q1 and Q2 are realized by Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) (MOS transistor for short), and may also be realized by other switching elements in other examples. When one of the switches Q1 or Q2 is turned on, the primary winding of the main transformer T1 is energized and accordingly the secondary winding of T1 is energized. When the secondary coil of T1 is energized, transformed power is generated, which is then rectified by the rectifier in the DC-DC converter 312 and passed to the output terminal connected to the multi-phase DC-DC converter 300 (333, 334) load I2.

The capacitors C1 and C2 in the DC-DC converter 311 and the inductors L1 and T1 respectively form an important part of the resonant circuit.

In this example, the rectifier of the DC-DC converter 311 is a half-bridge rectifier consisting of switches D1, D3 and capacitors C5, C6. The switches D1 and D3 form the diode bridge arms of the half-bridge rectifier, and the capacitors C5 and C6 form the capacitor bridge arms of the half-bridge rectifier. The switches D1 , D3 are implemented by diodes, and in other examples may also be implemented by other switching elements such as MOSFETs. The switching elements in the rectifier can be various types of semiconductor switching devices such as diodes and MOS tubes. When the "rectifier" is a MOS tube, the drive circuit can be used to provide a drive signal for the MOS tube, so that the current of the N MOS tube only flows from the source to the drain.

The DC-DC converter 312 has the same structure as the DC-DC converter 311, including a switching unit composed of switches Q3 and Q4, a main transformer realized by a transformer T2, and a half circuit composed of switches D2, D4 and capacitors C7, C8. bridge rectifier, and is also included by the . A resonant circuit composed of capacitors C3, C4 and L2 and T2 respectively. The working principle of the DC-DC converter 312 is also the same as that of the DC-DC converter 311 , except that the driving signals of the two are different, which will not be described in detail here.

The differential mode inductor T3 is connected in series between the DC-DC converters 311 and 312 and the output terminals of the multiphase DC-DC converter 300, more specifically, the half-bridge rectifiers of the DC-DC converters 311 and 312 are connected in series Between the diode bridge arm and the capacitor bridge arm. It should be understood that in other examples, the differential mode inductor T3 may also be connected in series between the common output terminals of the DC-DC converters 311 and 312 and the output terminal of the multi-phase DC-DC converter 300 .

The capacitor C20 in the multiphase DC-DC converter 300 is connected in parallel between the input terminal of the multiphase DC-DC converter 300 and the DC-DC converters 311 and 312, and is used as the input of the multiphase DC-DC converter 300 Capacitors for energy storage to act as a power source during soft-start and to filter noise in the DC input voltage.

Preferably, the multiphase DC-DC converter 300 may also include filter capacitors C9 and/or C10 (or called output capacitors), which are connected in parallel between the common output terminals of the DC-DC converters 311 and 312 and the multiphase DC- between the output terminals of the DC converter 300 can be used to filter out the AC component and the high frequency component in the output current of the DC-DC converter, thereby filtering out the ripple in the output voltage of the multiphase DC-DC converter 300 . Although two filter capacitors C9 and C10 are shown in FIG. 3 , in practical applications, any number of filter capacitors may be used as desired.

In addition, preferably, in each single-phase DC-DC converter, the driving signal (for example provided by the driving circuit) of each switching element in the switching unit has a duty cycle of about 50% (preferably less than 50%), And there is a phase shift of 180 degrees between the driving signal of the first switching element and the driving signal of the second switching element in the switching unit. Here, the first switching element refers to a switching element that passes an input current in the first direction to the primary side coil of the main transformer when turned on, and the second switching element refers to a switching element that passes the primary side coil of the main transformer when turned on. A switching element that passes an input current in a second direction opposite to the first direction. For example, in the single-phase DC-DC converter 311, when the switching element Q1 (the first switching element) is turned on, the primary side coil of the main transformer T1 passes an input current in the first direction (for example, downward), and the switching element Q2 ( When the second switching element) is turned on, the primary side coil of T1 passes an input current in a second direction (for example, downward). Both the driving signals of switching elements Q1 and Q2 have a duty cycle of about 50%, and there is a phase shift of 180 degrees between the driving signals of Q1 and Q2. Thus, the Zero Voltage Switching (ZeroVoltage Switching, ZVS) mode (also called soft switching mode) can be better realized.

In addition, although in Figure 3 and the following example circuits, the primary and secondary sides of the main transformer use the same ground symbol, it should be understood that in practical applications, the ground connected to the primary side of the main transformer and the secondary side The connected ground is isolated. In addition, circuits on the primary side of the main transformer use a common ground, and circuits on the secondary side of the main transformer use a common ground.

In a multi-phase DC-DC converter, the resonant inductors L1 and L2 in the resonant circuit may be physical inductors that exist as entities, or may be parasitic inductances. In high voltage output applications, the transformation ratio of the main transformer of the multiphase DC-DC converter will be reduced to even less than 1, so the leakage inductance cannot be easily established as the resonant inductance. In the example circuit of Figure 3, the rectifier in the DC-DC converter is a half-bridge rectifier, which can step down the output voltage of the secondary side of the main transformer by about 1/2, so that the transformation ratio of the main transformer (ie turns ratio) to about 2:1, enabling sufficient leakage inductance (or called parasitic inductance) to be established as a resonant inductance on the secondary side of the main transformer. Therefore, the parasitic inductance of the main transformer can be used as the resonant inductors L1 and L2 without using physical inductors, thereby increasing power density to improve efficiency and save component costs.

In addition, the use of the half-bridge structure can also reduce the use of semiconductor devices in the circuit.

FIG. 4 shows the first switching element and the second switching element in the switching unit of the single-phase DC-DC converter (for example, DC-DC converter 311 ) respectively provided by the driving circuit to the multi-phase DC-DC converter 300. (e.g. Q1, Q2) example voltage waveform diagram of the drive signal. The operating frequency of the two driving signals 401 and 402 is fixed, the phase offset is 180°, and the frequency is substantially equal to the resonant frequency determined by the resonant capacitors (C1 and C2) and the resonant inductance (L1). Of course, the main transformer parasitic capacitances C5 and C6 will affect the resonant frequency. The duty cycle of these switch drive signals is about 50% (preferably no more than 50%), adjust the dead time and the magnetizing inductance of the main transformer to ensure that the switches (Q1, Q2, Q3, Q4) enter ZVS mode during the dead time .

FIG. 5 shows example waveform diagrams of currents and voltages of the multiphase DC-DC converter 300 . Waveform 501 represents the switch driving signal Vgs provided to a switching element (such as MOS transistor Q2) in the switching unit of DC-DC converter 311; waveform 502 represents the drain of the switching element (such as Q2) of DC-DC converter 311 Source voltage Vds; waveform 503 represents the input current of the main transformer of the DC-DC converter 311 . It can be seen that the input current of the main transformer of the DC-DC converter 311 is approximately a sine wave. The DC-DC converter 312 also has similar current and voltage waveforms, but is phase shifted by 90° compared to the waveforms of the DC-DC converter 311 . The current and voltage waveforms of the two DC-DC converters have a 90° phase shift, which can better eliminate the ripple in the output current, so the shared output capacitors C9 and C10 of the DC-DC converters 311 and 312 can be reduced value or number to save components.

Fig. 6 shows another example circuit diagram of the multi-phase DC-DC converter according to the first embodiment of the present invention. As shown in FIG. 6 , the multiphase DC-DC converter 600 includes two single-phase DC-DC converters 611 and 612 connected in parallel. The DC-DC converter 611 is shown by a dotted line box in the figure, and the DC-DC converter 612 is shown by a two-dot dash line box in the figure. The equalization circuit is realized by the differential mode inductor T3. The differential mode inductor T3 is connected in series between the common output terminals of the DC-DC converters 611 and 612 and the output terminal of the multiphase DC-DC converter 300, specifically, it is connected in series to the half-bridges of the DC-DC converters 611 and 612 Between the diode leg of the rectifier and the capacitor leg. Compared with the example circuit in Fig. 3, the switching units of DC-DC converters 611 and 612 in Fig. 6 are composed of four switching elements (Q1, Q2, Q31, Q32) and (Q3, Q4, Q33, Q34) composition. In addition, the resonant circuit in Figure 6 is composed of (C25, L1, T1) and (C26, L2, T2) respectively, wherein the capacitor 25 and the inductor L1 are connected in series at one output end of the switch unit of the DC-DC converter 611 (the output terminal between Q31 and Q32) and the primary side of the main transformer T1, the capacitor 26 and the inductor L2 are connected in series to one output terminal of the switching unit of the DC-DC converter 612 (the output terminal between Q33 and Q34 terminal) and the primary side of the main transformer T2. The multi-phase DC-DC converter 600 can provide relatively large input power by using a full-bridge switching unit.

Similar to the circuit in FIG. 3, in the circuit in FIG. 6, preferably, the driving signal (for example, provided by the driving circuit) of each switching element in the switching unit may have a duty cycle of about 50% (preferably less than 50%). Duty ratio, and there may be a 180-degree phase shift between the driving signal of the first switching element and the driving signal of the second switching element in the switching unit, so as to better realize the ZVS mode. In FIG. 6, for example, in the single-phase DC-DC converter 631, the switching elements Q1 and Q32 pass the input current in the first direction (for example, downward) to the primary side coil of the main transformer T1, and the switching elements Q2 and Q31 Make the primary side coil of the main transformer T1 pass an input current in a second direction (for example, upward) opposite to the first direction. Therefore, there may be a phase shift of 180 degrees between the driving signal of the switching element (Q1, Q32) (first switching element) and the driving signal of the switching element (Q2, Q32) (second switching element), and each switching element The duty ratios of the driving signals (Q1, Q2, Q31, Q32) are all about 50%.

Fig. 7 shows yet another exemplary circuit diagram of the multi-phase DC-DC converter according to the first embodiment of the present invention. As shown in FIG. 7 , the multiphase DC-DC converter 700 includes two single-phase DC-DC converters 711 and 712 connected in parallel. The DC-DC converter 711 is shown by a dotted line box in the figure, and the DC-DC converter 712 is shown by a two-dot dash line box in the figure. The equalization circuit is realized by the differential mode inductor T3. The differential mode inductor T3 is connected in series between the common output terminals of the DC-DC converters 711 and 712 and the output terminal of the multiphase DC-DC converter 700 . Compared with the example circuit in FIG. 3 , the DC-DC converters 711 and 712 in FIG. 6 both use full-bridge rectifiers. Specifically, the rectifier of the DC-DC converter 711 is composed of four switches (diodes as shown, or other switching elements) D1, D3, D5, D6 connected in a full bridge, and the DC-DC converter 712 The rectifier consists of four switches (diodes as shown but could be other switching elements) D2, D4, D7, D8 connected in a full bridge. In addition, as an example and not a limitation, the multi-phase DC-DC converter 700 is provided with a DC input voltage by series-connected batteries in FIG. 7 . In the case of using a full bridge rectifier, resonant inductors L1 and L2 are physical inductors. By using a full-bridge rectifier, the output terminal of the main transformer can provide more power, so that the multi-phase DC-DC converter 700 can provide higher output power.

Fig. 8 shows another example circuit diagram of the multi-phase DC-DC converter according to the first embodiment of the present invention. As shown in FIG. 8 , the multiphase DC-DC converter 800 includes two single-phase DC-DC converters 811 and 812 connected in parallel. The DC-DC converter 811 is shown by the dotted line box and the dotted line box in the figure, and the DC-DC converter 812 is shown by the double dotted line box and the dotted line box in the figure. The equalization circuit is realized by the differential mode inductor T3. Compared with the example circuit of FIG. 3 , the DC-DC converters 811 and 812 in the multiphase DC-DC converter 800 have a common capacitor bridge arm. The shared capacitor bridge arm is composed of capacitors C54, C55, which are shown by dotted line boxes in FIG. 8 . The differential mode inductor T3 is connected in series between the common output terminals of the DC-DC converters 811 and 812 and the output terminal of the multiphase DC-DC converter 300, specifically, it is connected in series to the half-bridges of the DC-DC converters 811 and 812 Between the diode leg of the rectifier and the common capacitor leg. By having multiple single-phase DC-DC converters (811, 812) with a common capacitor bridge arm, component cost can be saved.

FIG. 9 shows another example circuit diagram of the multiphase DC-DC converter according to the first embodiment of the present invention. Compared with the example circuit of FIG. 3 , the multiphase DC-DC converter 900 shown in FIG. 9 includes three DC-DC converters 911 , 912 and 913 connected in parallel. The DC-DC converter 911 is shown by a dotted line box in the figure, the DC-DC converter 912 is shown by a double-dashed line box in the figure, and the DC-DC converter 913 is shown by a dot-dash line box in the figure. The equalization circuit is realized by the differential mode inductor T3. The differential mode inductor T3 is connected in series between the common output terminals of the DC-DC converters 911, 912 and 913 and the output terminal of the multiphase DC-DC converter 900, specifically between the DC-DC converters 911, Between the diode bridge arm and the capacitor bridge arm of the half-bridge rectifier of 912 and 913. The circuit structures of the DC-DC converters 911 , 912 and 913 are the same, and are the same as the circuit structure of the DC-DC converter 311 shown in FIG. 3 , so the description will not be repeated here. It should be understood that the DC-DC converters 911, 912 and 913 may also have different circuit structures from the DC-DC converter 311, and/or the circuit structures of the DC-DC converters 911, 912 and 913 may also be different from each other, here Not described in detail.

In addition to the structure of the above example circuit, the switching unit and the rectifier of each single-phase DC-DC converter may be of full bridge structure, which will not be described in detail here.

The above shows an example circuit where the equalization circuit is located on the output side of the multiphase DC-DC converter. The situation that the equalization circuit is located at the input side of the multi-phase DC-DC converter will be described below with reference to the accompanying drawings.

Fig. 10 shows a schematic block diagram of a multiphase DC-DC converter according to a second embodiment of the present invention. In the second embodiment of the present utility model, the equalization circuit is arranged between a plurality of single-phase DC-DC converters connected in parallel and the input ends of the multi-phase DC-DC converters, and is used to equalize a plurality of single-phase DC-DC converters. The input current of the DC converter. As shown in Figure 10, the multiphase DC-DC converter 1000 includes: input terminals (1031, 1032) for receiving a DC input voltage Vin; multiple single-phase DC-DC converters (1011, 1012,  … , 101n), used to convert the DC input voltage Vin to DC-DC, where n is a positive integer greater than 1; the output terminal (1033, 1034) is used to output the DC converted by multiple single-phase DC-DC converters output voltage Vout; and an equalizing circuit (1020), connected in series with a plurality of single-phase DC-DC converters (1011, 1012, ..., 101n) connected in parallel, and provided at the plurality of single-phase DC-DC converters (1011 , 1012, ..., 101n) and the input terminals (1031, 1032), used to balance the input current of the multiple single-phase DC-DC converters.

In this embodiment, the DC-DC converters (111, 112, ..., 11n) can be realized by using various single-phase DC-DC converters with appropriate structures, such as forward converters, bridge converters, push-pull type converter, etc., without limitation.

In this embodiment, the equalization circuit 1020 can be implemented by using an equalization circuit with an appropriate structure. For example, the equalization circuit 1020 may be implemented using a differential mode inductor or an LC circuit.

The multi-phase DC-DC converter 1000 also includes a driving circuit (not shown) for driving the multiple single-phase DC-DC converters (1011, 1012, ..., 101n), so that the multiple The phases of the output currents of the single-phase DC-DC converter have a predetermined phase shift from each other. Any suitable configuration of drive circuits may be used here. Since the driving circuit is not a necessary component to solve the technical problems of the present invention, in order not to obscure the present invention, the driving circuit will not be described in detail here and below.

FIG. 11A shows an example circuit diagram of an equalization circuit in a multiphase DC-DC converter according to a second embodiment of the present invention. In this example, the multiphase DC-DC converter 1100 employs a differential mode inductor 1120 to implement a balancing circuit. As shown in Figure 11, the first coil of the differential mode inductor 1120 is connected in series with the first common input end 1141 of multiple single-phase DC-DC converters (1111, 1112, ..., 111n) and the multi-phase DC-DC converter Between the first input terminal 1131 of the differential mode inductor 1120, the second coil of the differential mode inductor 1120 is connected in series with the second common input terminal 1142 of a plurality of single-phase DC-DC converters (1111, 1112, ..., 111n) and the multi-phase DC- between the second input terminals 1132 of the DC converter. The first input terminal 1131 and the second input terminal 1132 are respectively connected to the same-named terminal of one coil of the differential mode inductor 1120 and the non-identical terminal of the other coil. In this way, the direction of the current flowing into the two coils of the differential mode inductor is opposite, and the magnetic flux generated by the initial current in each coil induces in the other coil an induction current opposite to the direction of the initial current in the other coil. Thereby, the difference of the currents flowing in the two coils is reduced, thereby reducing the difference of the input currents of the multiple single-phase DC-DC converters (1111, 1112, . . . , 111n).

In this example, the dotted ends of the two coils of the differential mode inductor (represented by the black dots in the diagram) are on one side. In other examples, the ends with the same name of the two coils of the differential mode inductor can also be on opposite sides, and the first input end 1131 and the second input end 1132 can still be respectively connected to the end with the same name of one coil of the differential mode inductor 1120 and The non-identical end of the other coil, as shown in Figure 11B.

FIG. 12 shows an example circuit diagram of a multiphase DC-DC converter according to a second embodiment of the present invention. As shown in FIG. 12 , the multiphase DC-DC converter 1200 includes two single-phase DC-DC converters 1211 and 1212 connected in parallel. The DC-DC converter 1211 is shown by a dotted line box in the figure, and the DC-DC converter 1212 is shown by a two-dot dash line box in the figure. The equalization circuit is realized by the differential mode inductor T4. The structures of the DC-DC converters 1211 and 1212 are respectively the same as those of the DC-DC converters 711 and 712 shown in FIG. 7 , and will not be repeated here.

The differential mode inductor T4 is connected in series between the DC-DC converters 1211 and 1212 and the input terminals of the multiphase DC-DC converter 1200, more specifically, connected in series at the common input terminals of the DC-DC converters 1211 and 1212 ( 1241 , 1242 ) and the input terminals ( 1231 , 1232 ) of the multiphase DC-DC converter 1200 .

Other components and connections in the multiphase DC-DC converter 1200 are the same as those shown in FIG. 7 and will not be repeated here.

The multiphase DC-DC converter 1200 shown in FIG. 12 uses a full-bridge rectifier to enable the output end of the main transformer to provide greater power, thereby providing higher output power.

Fig. 13 shows another example circuit diagram of the multi-phase DC-DC converter according to the second embodiment of the present invention. Compared with the example circuit of FIG. 12 , the multiphase DC-DC converter 900 shown in FIG. 13 includes three DC-DC converters 1311 , 1312 and 1313 connected in parallel. The DC-DC converter 1311 is shown by a dotted line box in the figure, the DC-DC converter 1312 is shown by a double-dashed line box in the figure, and the DC-DC converter 1313 is shown by a dot-dash line box in the figure. The equalization circuit is realized by the differential mode inductor T4. The differential mode inductor T4 is connected in series between the common input terminals ( 1341 , 1342 ) of the DC-DC converters 1311 , 1312 and 1313 and the input terminals ( 1331 , 1332 ) of the multiphase DC-DC converter 1300 . The circuit structures of the DC-DC converters 1311, 1312 and 1313 are the same, and are the same as the circuit structure of the DC-DC converter 311 shown in FIG. 3, so the description will not be repeated here. It should be understood that the DC-DC converters 1311, 1312 and 1313 may also have different circuit structures from the DC-DC converter 311, and/or the circuit structures of the DC-DC converters 1311, 1312 and 1313 may also be different from each other, here Not described in detail.

In the example of FIG. 12 , the switching unit of the single-phase DC-DC converter has a half-bridge structure, and the rectifier has a full-bridge structure. In the example of FIG. 13 , both the switching unit and the rectifier of the single-phase DC-DC converter have a half-bridge structure. In other examples of the second embodiment of the present invention, the switching unit and the rectifier of each single-phase DC-DC converter may also be a full-bridge structure and a half-bridge structure respectively, or both may be a full-bridge structure; Alternatively, other structures may be used, which will not be described in detail here.

FIG. 14 shows another example circuit diagram of the equalization circuit in the multiphase DC-DC converter according to the second embodiment of the present invention. In this example, multiphase DC-DC converter 1400 employs an LC circuit to implement equalization circuit 1420 . As shown in FIG. 14, equalization circuit 1420 includes an inductor and a capacitor connected in series. One end of the inductor connected to the capacitor is connected to a first common input 1441 of a plurality of single-phase DC-DC converters (1411, 1412, ..., 141n), and the other end of the inductor is connected to a multi-phase DC- The first input terminal 1431 of the DC converter 1400 . The end of the capacitor not connected to the inductor is connected to the second input of the multiphase DC-DC converter 1400 and to the second input of the plurality of single-phase DC-DC converters (1411, 1412, . Common input 1442. The equalization circuit 1420 composed of inductors and capacitors can change the impedance characteristics of the single-phase DC-DC converter at the operating frequency, and play the same role as the differential mode inductor, thereby reducing the number of single-phase DC-DC converters. ( 1411 , 1412 , . . . , 141n ) differ in input current to realize current balance between multi-phase DC-DC.

FIG. 15 shows an example circuit diagram of the multiphase DC-DC converter shown in FIG. 14 . As shown in FIG. 15 , the multiphase DC-DC converter 1500 includes two single-phase DC-DC converters 1511 and 1512 connected in parallel. The DC-DC converter 1511 is shown by a dotted line box in the figure, and the DC-DC converter 1512 is shown by a two-dot dash line box in the figure. The structures of the DC-DC converters 1511 and 1512 are respectively the same as those of the DC-DC converters 311 and 312 shown in FIG. 3 , and will not be repeated here. The equalization circuit is realized by inductor L10 and capacitor C67. An inductor L10 and a capacitor C67 connected in series are connected on the input side of the multiphase DC-DC converter 1500 . One end of the inductor L10 connected to the capacitor C67 is connected to the first common input end 1541 of the DC-DC converters 1511 and 1512 , and the other end of the inductor L10 is connected to the first input end 1531 of the multiphase DC-DC converter 1500 . The end of capacitor C67 not connected to inductor L10 is connected to the second input terminal of multiphase DC-DC converter 1500 and to the second common input terminal 1542 of DC-DC converters 1511 and 1512 .

In order to further optimize the circuit, the multiphase DC-DC converter 150 may also include a resistor R13 and a capacitor C42 connected in parallel with the inductor L10 and connected in series with each other to play a filtering role; and connected in series in the multiphase DC-DC The resistor R14 and the capacitor C43 between the first input terminal 1531 and the second input terminal 1532 of the converter 150 are connected in parallel with the capacitor C67 to function as a filter.

Other components and connections in the multiphase DC-DC converter 1500 are the same as those shown in FIG. 3 , and will not be repeated here.

In the example of FIG. 15 , the switching unit and the rectifier of each single-phase DC-DC converter have a half-bridge structure. It should be understood that, in other examples using a balanced circuit composed of inductors and capacitors, the switching unit and the rectifier of each single-phase DC-DC converter may also be a full-bridge structure and a half-bridge structure, or a half-bridge structure structure and full bridge structure, or both are full bridge structure. Alternatively, a single-phase DC-DC converter with other structures may be used, which will not be described in detail here.

The example circuit of the multi-phase DC-DC converter according to the embodiment of the present utility model is described above by taking the bridge DC-DC converter as an example. In other embodiments of the present utility model, multiple single-phase DC-DC converters in the multi-phase DC-DC converter can be realized by adopting other single-phase DC-DC converters with appropriate structures, such as forward converters, The connection method of the push-pull converter and the equalization circuit is the same as that described here, and will not be described one by one.

In addition, in the example circuit of FIG. 15, a balancing circuit consisting of inductors and capacitors is connected between the input terminal of the multi-phase DC-DC converter and the common input terminal of a plurality of single-phase DC-DC converters. In other examples such as the first embodiment of the utility model, the equalization circuit composed of inductors and capacitors can also be connected between the common output terminals of multiple single-phase DC-DC converters and the multi-phase DC-DC converters Between the output terminals, it will not be described in detail here.

According to the multi-phase DC-DC converter of the embodiment of the present invention, by connecting the balance circuit and a plurality of single-phase DC-DC converters connected in parallel in series between the input end and the output end of the multi-phase DC-DC converter During this period, the currents of multiple single-phase DC-DC converters can be balanced, and the difference between the input currents or output currents of multiple single-phase DC-DC converters can be reduced. In some examples according to embodiments of the present invention, multiple single-phase DC-DC converters in a multi-phase DC-DC converter may use a rectifier with a half-bridge structure, so that the secondary side of the slave main transformer may be utilized The reflected parasitic inductance acts as a resonant inductor, eliminating the need for a physical inductor, increasing power density for higher efficiency and saving component overhead. In some examples according to embodiments of the present invention, rectifiers in multiple single-phase DC-DC converters in a multi-phase DC-DC converter can use a common capacitor bridge arm, thereby saving component costs.

The multi-phase DC-DC converter according to the embodiment of the present utility model can be applied, for example, to an on-board charger of telecommunication products or automobiles (such as electric vehicles).

In the above description of specific embodiments of the present invention, features described and/or illustrated for one embodiment can be used in one or more other embodiments in the same or similar manner, and Features may be combined or substituted for features in other embodiments.

It should be emphasized that the term "comprising/comprising" when used herein refers to the presence of a feature, element, step or component, but does not exclude the presence or addition of one or more other features, elements, steps or components.

Although the embodiments of the present utility model have been described in detail in conjunction with the accompanying drawings, it should be understood that the above described embodiments are only used to illustrate the present utility model, and do not constitute a limitation to the present utility model. Those skilled in the art can make various modifications and changes to the above-mentioned embodiments without departing from the essence and scope of the present invention. Therefore, the scope of the present invention is limited only by the appended claims and their equivalents.

Claims (13)

1. a multiphase DC-DC converter, comprising:

Input, for receiving DC input voitage;

The multiple single-phase DC-DC converter being connected in parallel, for carrying out DC-DC conversion by described DC input voitage;

Output, for exporting the VD through described multiple single-phase DC-DC converter conversion; And

Equalizing circuit, and the described multiple single-phase DC-DC converter being connected in parallel is connected in series between described input and described output, for the electric current of the described multiple single-phase DC-DC converters of equilibrium.

2. multiphase DC-DC converter according to claim 1, also comprises drive circuit, for driving described multiple single-phase DC-DC converter, has each other predetermined phase shift with the phase place of the output current that makes described multiple single-phase DC-DC converters.

3. multiphase DC-DC converter according to claim 1, wherein, described equalizing circuit is made up of differential mode inductance.

4. multiphase DC-DC converter according to claim 3, wherein, described output comprises the first output and the second output, the first coil of described differential mode inductance is connected in series between first common output and described the first output of described multiple single-phase DC-DC converters, and the second coil of described differential mode inductance is connected in series between second common output and described the second output of described multiple single-phase DC-DC converters.

5. multiphase DC-DC converter according to claim 3, wherein, described input comprises first input end and the second input, the first coil of described differential mode inductance is connected in series between described first input end and the first shared input of described multiple single-phase DC-DC converters, and the second coil of described differential mode inductance is connected in series between described the second input and the second shared input of described multiple single-phase DC-DC converters.

6. multiphase DC-DC converter according to claim 1, wherein, described equalizing circuit is made up of the inductor being connected in series and capacitor, and

Wherein, described input comprises first input end and the second input, one end that described inductor is connected with described capacitor is connected to the first shared input of described multiple single-phase DC-DC converters, the other end of described inductor is connected to described first input end, and one end not being connected with described inductor of described capacitor is connected to described the second input and is connected to the second shared input of described multiple single-phase DC-DC converters.

7. multiphase DC-DC converter according to claim 1, wherein, each the comprising in described multiple single-phase DC-DC transformers:

Main transformer, for carrying out transformation to described DC input voitage;

Switch element, comprise multiple switch elements, be arranged between the input of described single-phase DC-DC converter and the primary side of described main transformer, for operating by turning on and off of described multiple switch elements the primary side that described DC input voitage is provided to described main transformer; And

Rectifier, is connected between the primary side of described main transformer and the output of described single-phase DC-DC converter, carries out rectification for the voltage of the primary side output to described main transformer, to export described VD,

Wherein, described rectifier is full-bridge rectifier or half bridge rectifier.

8. multiphase DC-DC converter according to claim 7, wherein, described rectifier is half bridge rectifier, and the half bridge rectifier of described multiple single-phase DC-DC transformers has shared capacitor brachium pontis.

9. multiphase DC-DC converter according to claim 7, wherein, described rectifier is half bridge rectifier, and described equalizing circuit is connected between the diode brachium pontis and capacitor brachium pontis of described half bridge rectifier.

10. multiphase DC-DC converter according to claim 7, wherein, described switch element comprises the two or four switch element that bridge-type connects.

11. multiphase DC-DC converters according to claim 1, also comprise at least one filtering capacitor being connected in parallel between described multiple single-phase DC-DC converters and described equalizing circuit and described output, for the ripple of the output voltage of multiple single-phase DC-DC converters described in filtering.

12. multiphase DC-DC converters according to claim 7, wherein, in each single-phase DC-DC converter, in described switch element, the driving signal of each switch element has about 50% duty ratio, and between the driving signal of the first switch element in described switch element and the driving signal of second switch element, there is the phase shift of 180 degree, described the first switch element makes the primary side coil of described main transformer by the input current of first direction in the time of conducting, and described second switch element makes the primary side coil of described main transformer by the input current of the second direction contrary with first direction in the time of conducting.

13. multiphase DC-DC converters according to claim 2, wherein, described predetermined phase shift is 180 °/n, n is the number of described multiple single-phase DC-DC converters.

Images