CN115882722A - Hybrid Buck-Boost DC-DC Converter with Flying Capacitor - Google Patents
Hybrid Buck-Boost DC-DC Converter with Flying Capacitor Download PDFInfo
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Abstract
Description
技术领域technical field
本公开涉及电子器件、集成电路技术领域,尤其涉及一种具有飞电容的混合降压-升压直流-直流转换器。The present disclosure relates to the technical fields of electronic devices and integrated circuits, and in particular to a hybrid buck-boost DC-DC converter with flying capacitors.
背景技术Background technique
在电池供电的移动设备中,系统电路需要的实际供电电压可能高于电池电压或者低于电池电压。最典型的应用场景:由锂电池供电,产生一个固定的3.3V给系统供电,而随着锂电池使用时间的增加,电池电压从5V降到2.5V。因此,当电池电压高于3.3V时,系统需要一个降压直流-直流转换器,当电池电压低于3.3V时,系统需要一个升压直流-直流转换器。在这种情况下,同时具有升压和降压功能的降压-升压直流-直流转换器提供了良好的解决方案。In battery-powered mobile devices, the actual supply voltage required by the system circuits may be higher or lower than the battery voltage. The most typical application scenario: powered by a lithium battery, a fixed 3.3V is generated to power the system, and as the lithium battery's usage time increases, the battery voltage drops from 5V to 2.5V. Therefore, the system needs a buck DC-DC converter when the battery voltage is higher than 3.3V, and a step-up DC-DC converter when the battery voltage is lower than 3.3V. In this case, a buck-boost DC-DC converter with both step-up and step-down functions provides a good solution.
传统的降压-升压转换器是将传统的升压转换器和降压转换器级联,因此在功率路径上,一直会有两个功率管与电感串联,而单纯的升压或是降压转换器只有一个功率管与电感串联,因此传统的降压-升压转换器的导通损耗会很大,为了提升效率,只能将功率管的面积加大以降低功率管的导通电阻,这无疑会大大增加芯片的制造成本。The traditional buck-boost converter is to cascade the traditional boost converter and buck converter, so in the power path, there will always be two power transistors connected in series with the inductor, and the pure boost or buck There is only one power tube in series with the inductor in the voltage converter, so the conduction loss of the traditional buck-boost converter will be very large. In order to improve the efficiency, the area of the power tube can only be increased to reduce the on-resistance of the power tube , which will undoubtedly greatly increase the manufacturing cost of the chip.
此外,传统的降压-升压转换器的电感在升压模式或者降压模式时都处在大电流侧,换言之,电感电流都会很大,为了保证系统效率,需要选择小DCR(直流电阻)的电感,而对于电感来说,DCR越小,尺寸会越大,这不仅增大了芯片的体积,还增加了成本。In addition, the inductor of the traditional buck-boost converter is on the high current side in the boost mode or the buck mode. In other words, the inductor current will be very large. In order to ensure the system efficiency, it is necessary to choose a small DCR The inductance, and for the inductance, the smaller the DCR, the larger the size, which not only increases the size of the chip, but also increases the cost.
发明内容Contents of the invention
(一)要解决的技术问题(1) Technical problems to be solved
基于上述问题,本公开提供了一种具有飞电容的混合降压-升压直流-直流转换器,以缓解现有技术中降压-升压转换器体积大、改善效率的成本较高等技术问题。Based on the above problems, the present disclosure provides a hybrid buck-boost DC-DC converter with flying capacitors to alleviate technical problems in the prior art such as large volume of buck-boost converters and high cost of improving efficiency .
(二)技术方案(2) Technical solution
本公开提供一种具有飞电容的混合降压-升压直流-直流转换器,包括:输入节点,功率电感,飞电容,第一开关管,第二开关管,第三开关管,第四开关管,输出端。输入节点连接至输入电压源,用于接收输入电压;功率电感的一端连接至输入节点,另一端连接至第一开关节点;飞电容的一端连接至所述第一开关节点,飞电容另一端连接至第二开关节点;第一开关管的一端连接至第二开关节点,另一端接地;第二开关管的一端连接至所述输入节点,另一端连接至所述第二开关节点;第三开关管的一端连接至所述第一开关节点,另一端连接至输出节点,所述输出节点用于发出输出电压;第四开关管的一端连接至第二开关节点,另一端连接至输出节点;输出端与输出节点相连,所述输出端包括并联设置的输出电容和负载电阻,所述输出端在输出电压的作用下产生负载电流。The present disclosure provides a hybrid buck-boost DC-DC converter with a flying capacitor, including: an input node, a power inductor, a flying capacitor, a first switching tube, a second switching tube, a third switching tube, and a fourth switch tube, output. The input node is connected to the input voltage source for receiving the input voltage; one end of the power inductor is connected to the input node, and the other end is connected to the first switching node; one end of the flying capacitor is connected to the first switching node, and the other end of the flying capacitor is connected to to the second switch node; one end of the first switch tube is connected to the second switch node, and the other end is grounded; one end of the second switch tube is connected to the input node, and the other end is connected to the second switch node; the third switch One end of the tube is connected to the first switch node, and the other end is connected to the output node, and the output node is used to send an output voltage; one end of the fourth switch tube is connected to the second switch node, and the other end is connected to the output node; output The terminal is connected to the output node, the output terminal includes an output capacitor and a load resistor arranged in parallel, and the output terminal generates a load current under the action of the output voltage.
根据本公开的实施例,当输入电压高于输出电压时,转换器工作在降压模式,当输入电压小于输出电压时,转换器工作在升压模式。According to an embodiment of the present disclosure, when the input voltage is higher than the output voltage, the converter works in a buck mode, and when the input voltage is lower than the output voltage, the converter works in a boost mode.
根据本公开的实施例,升压模式时,第四开关管始终断开,依据第一开关管、第二开关管和第三开关管的联动状态将升压模式分为第一状态和第二状态。According to the embodiment of the present disclosure, in the boost mode, the fourth switch tube is always off, and the boost mode is divided into the first state and the second state according to the linkage state of the first switch tube, the second switch tube and the third switch tube. state.
根据本公开的实施例,第一状态时,第一开关管导通,第二开关管和第三开关管断开;第一开关节点电压小于输入电压,功率电感两端压差大于0,功率电感充磁,功率电感的电流上升并向飞电容充电。According to an embodiment of the present disclosure, in the first state, the first switch tube is turned on, the second switch tube and the third switch tube are turned off; the voltage of the first switch node is lower than the input voltage, the voltage difference across the power inductor is greater than 0, and the power The inductor is magnetized, and the current of the power inductor rises and charges the flying capacitor.
根据本公开的实施例,第二状态时,第一开关管断开,第二开关管和第三开关管导通,第一开关节点的电压与输出节点电压相同,第二开关节点的电压等于输入电压,第一开关节点的电压大于输入电压,功率电感两端压差小于0,功率电感电感去磁,功率电感的电流下降,飞电容放电向输出电容传输电荷。According to an embodiment of the present disclosure, in the second state, the first switch tube is turned off, the second switch tube and the third switch tube are turned on, the voltage of the first switch node is the same as the voltage of the output node, and the voltage of the second switch node is equal to The input voltage, the voltage of the first switching node is greater than the input voltage, the voltage difference between the two ends of the power inductor is less than 0, the power inductor is demagnetized, the current of the power inductor drops, and the flying capacitor discharges to transfer charge to the output capacitor.
根据本公开的实施例,降压模式时,第二开关管始终断开,依据第一开关管和第三开关管、第四开关管的联动状态将降压模式分为第三状态和第四状态。According to the embodiment of the present disclosure, in the step-down mode, the second switch tube is always off, and the step-down mode is divided into the third state and the fourth state according to the linkage state of the first switch tube, the third switch tube, and the fourth switch tube. state.
根据本公开的实施例,第三状态时,第一开关管和第三开关管导通,第四开关管断开,第一开关节点的电压等于输出电压,第二开关节点的电压为0,第一开关节点的电压小于输入电压,功率电感两端压差大于0,功率电感充磁,功率电感电流上升,飞电容放电,电荷流到输出电容。According to an embodiment of the present disclosure, in the third state, the first switch tube and the third switch tube are turned on, the fourth switch tube is turned off, the voltage of the first switch node is equal to the output voltage, and the voltage of the second switch node is 0, The voltage of the first switch node is lower than the input voltage, the voltage difference between the two ends of the power inductor is greater than 0, the power inductor is magnetized, the current of the power inductor rises, the flying capacitor is discharged, and the charge flows to the output capacitor.
根据本公开的实施例,第四状态时,第一开关管和第三开关管断开,第四开关管导通,第一开关节点电压为两倍的输出电压,第二开关节点的电压等于输出电压,第一开关节点电压大于输入电压,功率电感两端压差小于0,功率电感去磁,功率电感电流下降,飞电容充电。According to an embodiment of the present disclosure, in the fourth state, the first switch tube and the third switch tube are turned off, the fourth switch tube is turned on, the voltage of the first switch node is twice the output voltage, and the voltage of the second switch node is equal to The output voltage, the voltage of the first switch node is greater than the input voltage, the voltage difference across the power inductor is less than 0, the power inductor is demagnetized, the current of the power inductor drops, and the flying capacitor is charged.
根据本公开的实施例,升压模式时,功率电感电流等于负载电流;第一开关管,第二开关管,第三开关管选用最大耐压值为输入电压的开关管,第四开关管选用最大耐压值为输出电压的开关管。According to an embodiment of the present disclosure, in the boost mode, the power inductor current is equal to the load current; the first switch tube, the second switch tube, and the third switch tube select the switch tube whose maximum withstand voltage is the input voltage, and the fourth switch tube selects The switching tube whose maximum withstand voltage is the output voltage.
根据本公开的实施例,降压模式时,功率电感电流小于负载电流,第一开关管,第三开关管,第四开关管选用最大耐压值为输出电压的开关管,第二开关管选用最大耐压值为输入电压的开关管。According to an embodiment of the present disclosure, in the step-down mode, the power inductor current is smaller than the load current, the first switch tube, the third switch tube, and the fourth switch tube select the switch tube whose maximum withstand voltage is the output voltage, and the second switch tube selects The switch tube whose maximum withstand voltage is the input voltage.
(三)有益效果(3) Beneficial effects
从上述技术方案可以看出,本公开具有飞电容的混合降压-升压直流-直流转换器至少具有以下有益效果其中之一或其中一部分:It can be seen from the above technical solutions that the disclosed hybrid buck-boost DC-DC converter with flying capacitors has at least one or part of the following beneficial effects:
(1)降压模式和升压模式下都能降低电感上的电流,因此保证了高效率;(1) Both the buck mode and the boost mode can reduce the current on the inductor, thus ensuring high efficiency;
(2)在保证高效率的前提下,可以选用DCR较大的电感,电感尺寸可以降低;(2) On the premise of ensuring high efficiency, an inductor with a larger DCR can be selected, and the size of the inductor can be reduced;
(3)在降低了电感电流的同时,各个开关管上的电流也会降低,开关管的导通损耗大大降低;(3) While reducing the inductor current, the current on each switch tube will also be reduced, and the conduction loss of the switch tube is greatly reduced;
(4)系统中开关管最大耐压值为VIN(5V)或耐压值相近的开关管,不需要高耐压的管子,在保证系统高效率的前提下,可以降低开关管的尺寸,节省芯片面积,降低芯片制造成本。(4) The maximum withstand voltage value of the switch tube in the system is V IN (5V) or a switch tube with a similar withstand voltage value does not require a high withstand voltage tube. On the premise of ensuring high system efficiency, the size of the switch tube can be reduced. Save chip area and reduce chip manufacturing cost.
附图说明Description of drawings
图1a为传统降压-升压转换器的示意图。Figure 1a is a schematic diagram of a conventional buck-boost converter.
图1b为图1a所示的传统降压-升压转换器降压模式时的示意图。FIG. 1b is a schematic diagram of the conventional buck-boost converter shown in FIG. 1a in buck mode.
图1c为图1a所示的传统降压-升压转换器升压模式时的示意图。FIG. 1c is a schematic diagram of the conventional buck-boost converter shown in FIG. 1a in boost mode.
图2a为图1a所示的传统降压-升压转换器降压模式时的电路主要波形示意图。Fig. 2a is a schematic diagram of main waveforms of the circuit in the step-down mode of the conventional buck-boost converter shown in Fig. 1a.
图2b为图1a所示的传统降压-升压转换器升压模式时的电路主要键波形示意图。Fig. 2b is a schematic diagram of main key waveforms of the circuit in the boost mode of the traditional buck-boost converter shown in Fig. 1a.
图3a为现有技术中具有飞电容的降压-升压转换器的示意图。Fig. 3a is a schematic diagram of a buck-boost converter with a flying capacitor in the prior art.
图3b为图3a所示的现有技术中具有飞电容的降压-升压转换器降压模式时的示意图。Fig. 3b is a schematic diagram of the buck-boost converter with flying capacitor shown in Fig. 3a in the buck mode in the prior art.
图3c为图3a所示的现有技术中具有飞电容的降压-升压转换器升压模式时的示意图。FIG. 3c is a schematic diagram of the buck-boost converter with flying capacitor shown in FIG. 3a in boost mode in the prior art.
图4a为图3a所示的现有技术中具有飞电容的降压-升压转换器的降压模式时的电路主要波形示意图。FIG. 4a is a schematic diagram of main waveforms of the circuit in the buck mode of the buck-boost converter with flying capacitors shown in FIG. 3a in the prior art.
图4b为图3a所示的现有技术中具有飞电容的降压-升压转换器的升压模式时的电路主要波形示意图。FIG. 4b is a schematic diagram of main waveforms of the circuit in the boost mode of the buck-boost converter with flying capacitors shown in FIG. 3a in the prior art.
图5为本公开实施例的具有飞电容的混合降压-升压直流-直流转换器的示意图。FIG. 5 is a schematic diagram of a hybrid buck-boost DC-DC converter with flying capacitors according to an embodiment of the present disclosure.
图6a为图5所示的具有飞电容的混合降压-升压直流-直流转换器升压模式时第一状态的示意图。FIG. 6 a is a schematic diagram of a first state of the hybrid buck-boost DC-DC converter shown in FIG. 5 in boost mode.
图6b为图5所示的具有飞电容的混合降压-升压直流-直流转换器升压模式时第二状态的示意图。FIG. 6b is a schematic diagram of the second state of the hybrid buck-boost DC-DC converter shown in FIG. 5 in boost mode.
图7为本公开实施例的具有飞电容的混合降压-升压直流-直流转换器升压模式下的电路主要波形示意图。FIG. 7 is a schematic diagram of main waveforms of a hybrid buck-boost DC-DC converter with a flying capacitor in boost mode according to an embodiment of the present disclosure.
图8a为图5所示的具有飞电容的混合降压-升压直流-直流转换器降压模式时第三状态的示意图。FIG. 8 a is a schematic diagram of a third state of the hybrid buck-boost DC-DC converter shown in FIG. 5 in buck mode.
图8b为图5所示的具有飞电容的混合降压-升压直流-直流转换器降压模式时第四状态的示意图。FIG. 8 b is a schematic diagram of a fourth state of the hybrid buck-boost DC-DC converter shown in FIG. 5 in buck mode.
图9为本公开实施例的具有飞电容的混合降压-升压直流-直流转换器降压模式下的电路主要波形示意图。FIG. 9 is a schematic diagram of main waveforms of a hybrid buck-boost DC-DC converter with a flying capacitor in buck mode according to an embodiment of the present disclosure.
图10为本公开实施例的具有飞电容的混合降压-升压直流-直流转换器的工作流程示意图。FIG. 10 is a schematic diagram of a workflow of a hybrid buck-boost DC-DC converter with flying capacitors according to an embodiment of the present disclosure.
具体实施方式Detailed ways
本公开提供了一种具有飞电容的混合降压-升压直流-直流转换器,是一种全新的混合降压-升压直流-直流转换器拓扑结构,其在传统降压-升压转换器的基础上,引入1个飞电容,在升压模式和降压模式时都可以辅助电感向输出充电,以此降低电感电流。而且在降低电感电流的同时,也降低各个开关管上的电流,开关管的导通损耗也降低,同时并未引入耐压问题。The present disclosure provides a hybrid buck-boost DC-DC converter with flying capacitors, which is a brand-new topology of a hybrid buck-boost DC-DC converter, which can be used in traditional buck-boost conversion On the basis of the converter, a flying capacitor is introduced, which can assist the inductor to charge the output in both the boost mode and the buck mode, thereby reducing the inductor current. Moreover, while reducing the inductor current, the current on each switch tube is also reduced, and the conduction loss of the switch tube is also reduced, and at the same time, no problem of withstand voltage is introduced.
传统的降压-升压转换器如图1a所示,该转换器结构包含4个开关管S1,S2,S3,S4和1个功率电感L,1个输出电容COUT、及负载电阻ROUT。该电路有两种工作模式:A traditional buck-boost converter is shown in Figure 1a. The converter structure includes four switching tubes S 1 , S 2 , S 3 , and S 4 and a power inductor L, an output capacitor C OUT , and load resistor R OUT . The circuit has two modes of operation:
当输入电压大于输出电压(VIN>VOUT)时,如图1b所示,电路工作在降压模式,工作原理与传统降压转换器工作原理类似,S1,S2两个开关交替导通,S3常导通,开关节点VsW1在VIN和0之间切换。其电压转换比M(M=VOUT/VIN)、功率电感平均电流、占空比D的关系为:When the input voltage is greater than the output voltage (V IN > V OUT ), as shown in Figure 1b, the circuit works in the step-down mode. The working principle is similar to that of the traditional step-down converter. The two switches S 1 and S 2 alternately conduct is on, S 3 is normally on, and the switch node V sW1 switches between V IN and 0. The relationship between the voltage conversion ratio M (M=V OUT /V IN ), the average current of the power inductor, and the duty cycle D is:
M=D (1)M=D (1)
IL=IOUT (2)I L = I OUT (2)
其中D∈(0,1),M∈(0,1),IL为功率电感电流,IOUT为输出电流,或称为负载电阻ROUT的负载电流。Among them D ∈ (0, 1), M ∈ (0, 1), I L is the power inductor current, I OUT is the output current, or the load current of the load resistance R OUT .
当输入电压小于输出电压(VIN<VOUT)时,如图1c所示,电路工作在升压模式,工作原理与传统升压转换器工作原理类似,S3,S4两个开关管交替导通,S1常导通,第二开关节点VSW2在VOUT和0之间切换。其电压转换比M(M=VOUT/VIN)、电感平均电流与占空比D的关系为:When the input voltage is lower than the output voltage (V IN < V OUT ), as shown in Figure 1c, the circuit works in the boost mode, and the working principle is similar to that of the traditional boost converter. The two switches S 3 and S 4 alternate is turned on, S 1 is normally turned on, and the second switch node V SW2 is switched between V OUT and 0. The relationship between the voltage conversion ratio M (M=V OUT /V IN ), the average inductor current and the duty cycle D is:
M=1/(1-D) (3)M=1/(1-D) (3)
其中D∈(0,1),M∈(1,∞)。where D ∈ (0, 1), M ∈ (1, ∞).
该电路关键波形如图2a和图2b所示。由上述分析可以得知,传统降压-升压转换器在降压或是升压模式时,各有一个开关常导通(S3,S1),这大大增加了系统的导通损耗,为了降低导通损耗,则必须要加大开关的尺寸以获得更低的导通电阻,这将增加芯片制造的成本。同时,传统降压升压转换器在降压或是升压模式时,电感电流都很大,为了降低电感上的损耗,必须选用DCR较小的电感,而DCR越小,电感尺寸越大,这增加成本的同时还使得芯片体积变大。The key waveforms of the circuit are shown in Figure 2a and Figure 2b. From the above analysis, it can be known that when the traditional buck-boost converter is in the buck or boost mode, each switch is normally on (S 3 , S 1 ), which greatly increases the conduction loss of the system. In order to reduce the conduction loss, it is necessary to increase the size of the switch to obtain a lower conduction resistance, which will increase the cost of chip manufacturing. At the same time, when the traditional buck-boost converter is in the buck or boost mode, the inductor current is very large. In order to reduce the loss on the inductor, an inductor with a small DCR must be selected, and the smaller the DCR, the larger the inductor size. This increases the cost and also makes the chip larger.
为了降低导通损耗,ISSCC2017提出了一种新型拓扑结构,如图3a所示,该结构包括4个开关,1个功率电感L,1个飞电容CF,一个输出电容COUT,及负载电阻ROUT。In order to reduce the conduction loss, ISSCC2017 proposed a new topology structure, as shown in Figure 3a, the structure includes 4 switches, a power inductor L, a flying capacitor C F , an output capacitor C OUT , and a load resistor R OUT .
同样的,当输入电压大于输出电压(VIN>VOUT)时,电路工作在降压模式,如图3b所示,在降压模式下,就像传统降压转换器一样,只有两个开关S1,S2交替导通,开关节点在VIN和0之间切换,S3,S4一直断开,飞电容上没有任何充放电过程,相比于传统降压-升压转换器,功率路径上少了1个常导通的开关,如此便可以大大降低电路的导通损耗。降压模式下:Similarly, when the input voltage is greater than the output voltage (V IN > V OUT ), the circuit works in buck mode, as shown in Figure 3b. In buck mode, just like a traditional buck converter, there are only two switches S 1 and S 2 are turned on alternately, the switch node is switched between V IN and 0, S 3 and S 4 are always disconnected, and there is no charging and discharging process on the flying capacitor. Compared with the traditional buck-boost converter, There is one less normally-on switch on the power path, so that the conduction loss of the circuit can be greatly reduced. In buck mode:
M=D (5)M=D (5)
IL=IOUT (6)I L = I OUT (6)
其中D∈(0,1),M∈(0,1)。降压模式电路关键波形图如图4a所示。where D ∈ (0, 1), M ∈ (0, 1). The key waveform diagram of the step-down mode circuit is shown in Figure 4a.
当输入电压小于输出电压(VIN<VOUT)时,电路工作在升压模式,如图3c所示,电路中S1,S3,S4工作,S2一直断开。在DT-T时间段内,S1,S4导通飞电容充电,开关节点VSW1=VIN,第二开关节点压值VSW2=VOUT,VOUT<VIN,功率电感两端压差VSW1-VSW2<0,电感去磁,此时飞电容两端电压为VCF=VIN,在0-DT时间段内,S1,S4断开,S3导通,由于飞电容两端电压不能突变,所以此时第一开关节点压值VSW1=VOUT+VCF=VIN+VOUT,第二开关节点压值VSW2=VOUT,VSW1-VSW2>0,电感两端压差为正,电感充磁。不幸的是,此时S1上的电压应力为VIN+VOUT,因此S1需要更高耐压的功率管,这意味着芯片面积和制造成本的增加。在升压模式下:When the input voltage is lower than the output voltage (V IN < V OUT ), the circuit works in boost mode, as shown in Figure 3c, in which S 1 , S 3 , and S 4 work, and S 2 is always disconnected. During the DT-T time period, S 1 and S 4 are turned on to charge the flying capacitor, the switch node V SW1 = V IN , the voltage value of the second switch node V SW2 = V OUT , V OUT < V IN , the voltage across the power inductor If the difference V SW1 -V SW2 <0, the inductance is demagnetized. At this time , the voltage across the flying capacitor is V CF =V IN . The voltage across the capacitor cannot change abruptly, so at this time the voltage value of the first switch node V SW1 =V OUT +V CF =V IN +V OUT , the voltage value of the second switch node V SW2 =V OUT , V SW1 -V SW2 >0 , the voltage difference across the inductor is positive, and the inductor is magnetized. Unfortunately, the voltage stress on S 1 at this time is V IN +V OUT , so S 1 needs a power transistor with higher withstand voltage, which means an increase in chip area and manufacturing cost. In boost mode:
M=1/(1-D) (7)M=1/(1-D) (7)
其中D∈(0,1),M∈(1,∞),电感平均电流大于负载电流。升压模式电路关键波形图如图4b所示。Among them D ∈ (0, 1), M ∈ (1, ∞), the average inductor current is greater than the load current. The key waveform diagram of the boost mode circuit is shown in Figure 4b.
由上可知,如图1a所示的传统降压-升压转换器在升压模式和降压模式下都需要3个开关管,并且都有1个开关管常导通,导通损耗很大,为了实现高效率,必须要使用更大面积的开关管,这增加了芯片面积,增加了芯片制造成本。此外,升压模式和降压模式下电感电流都很大,为了实现高效率,必须要使用较小DCR的电感,DCR小的电感尺寸会更大,这增加了成本,增加了芯片的整体体积。如图3a所示的带有飞电容的降压一升压转换器,在降压模式时只有两个开关工作,升压模式时,3个开关工作,但是,不会像传统结构一样有一个开关管常导通,所以总的来说相较于传统结构来说,开关管的导通损耗会有所降低,但是其中S1需要一个高耐压的开关管,这会增加芯片面积和制造成本,降低系统效率。It can be seen from the above that the traditional buck-boost converter shown in Figure 1a requires three switching tubes in both boost mode and buck mode, and one switch tube is normally on, and the conduction loss is very large , in order to achieve high efficiency, it is necessary to use a switch tube with a larger area, which increases the chip area and increases the chip manufacturing cost. In addition, the inductor current is very large in boost mode and buck mode. In order to achieve high efficiency, it is necessary to use an inductor with a small DCR. The size of the inductor with a small DCR will be larger, which increases the cost and increases the overall volume of the chip. . In the buck-boost converter with flying capacitors shown in Figure 3a, only two switches work in the buck mode, and three switches work in the boost mode, but there is no one switch like the traditional structure. The switch tube is always on, so in general, compared with the traditional structure, the conduction loss of the switch tube will be reduced, but S1 needs a high withstand voltage switch tube, which will increase the chip area and manufacturing cost and reduce system efficiency.
此外,这两种结构的电感电流在升压模式和降压模式下都很大,所以都需要大尺寸的电感,同时,大的电感电流,也意味着开关管的导通损耗也会大。In addition, the inductor current of these two structures is very large in the boost mode and the buck mode, so a large-sized inductor is required. At the same time, a large inductor current also means that the conduction loss of the switch tube will also be large.
针对上述问题,本发明的目的是提出一种新型降压-升压转换器拓扑结构,在升压模式和降压模式下都能降低电感电流,降低开关管的导通损耗和电感DCR的损耗,同时不引入开关管的耐压问题,如此实现高效率的同时,大大降低芯片成本与体积。In response to the above problems, the purpose of the present invention is to propose a novel buck-boost converter topology, which can reduce the inductor current in both the boost mode and the buck mode, and reduce the conduction loss of the switch tube and the loss of the inductor DCR. , and at the same time does not introduce the withstand voltage problem of the switch tube, so as to achieve high efficiency and greatly reduce the cost and volume of the chip.
为使本公开的目的、技术方案和优点更加清楚明白,以下结合具体实施例,并参照附图,对本公开进一步详细说明。In order to make the purpose, technical solutions and advantages of the present disclosure clearer, the present disclosure will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.
在本公开实施例中,提供一种具有飞电容的混合降压-升压直流-直流转换器,如图5所示,所述具有飞电容的混合降压-升压直流-直流转换器,包括:In an embodiment of the present disclosure, a hybrid buck-boost DC-DC converter with a flying capacitor is provided, as shown in FIG. 5 , the hybrid buck-boost DC-DC converter with a flying capacitor, include:
输入节点,连接至输入电压源,用于接收输入电压VIN;An input node connected to an input voltage source for receiving an input voltage V IN ;
功率电感L,一端连接至输入节点,另一端连接至第一开关节点VSW1;A power inductor L, one end is connected to the input node, and the other end is connected to the first switch node V SW1 ;
飞电容CF,其一端连接至所述第一开关节点VSW1,飞电容另一端连接至第二开关节点VSW2;a flying capacitor C F , one end of which is connected to the first switch node V SW1 , and the other end of the flying capacitor is connected to the second switch node V SW2 ;
第一开关管S1,一端连接至第二开关节点VSW1,另一端接地;The first switching tube S 1 , one end is connected to the second switching node V SW1 , and the other end is grounded;
第二开关管S2,一端连接至所述输入节点,另一端连接至所述第二开关节点VSW2;The second switching tube S 2 , one end is connected to the input node, and the other end is connected to the second switching node V SW2 ;
第三开关管S3,一端连接至所述第一开关节点VSW1,另一端连接至输出节点,所述输出节点用于发出输出电压VOUT;A third switch tube S 3 , one end is connected to the first switch node V SW1 , and the other end is connected to an output node, and the output node is used to send out an output voltage V OUT ;
第四开关管S4,一端连接至第二开关节点VSW2,另一端连接至输出节点;The fourth switching tube S 4 , one end is connected to the second switching node V SW2 , and the other end is connected to the output node;
输出端,与输出节点相连,所述输出端包括并联设置的输出电容COUT和负载电阻ROUT,所述输出端在输出电压的作用下产生负载电流。The output terminal is connected to the output node, the output terminal includes an output capacitor C OUT and a load resistor R OUT arranged in parallel, and the output terminal generates a load current under the action of the output voltage.
当输入电压高于输出电压时,转换器工作在降压模式,当输入电压小于输出电压时,转换器工作在升压模式。升压模式时,第四开关管始终断开,依据第一开关管、第二开关管和第三开关管的联动状态将升压模式分为第一状态和第二状态。降压模式时,第二开关管始终断开,依据第一开关管和第三开关管、第四开关管的联动状态将降压模式分为第三状态和第四状态。When the input voltage is higher than the output voltage, the converter works in buck mode, and when the input voltage is lower than the output voltage, the converter works in boost mode. In the boost mode, the fourth switch tube is always turned off, and the boost mode is divided into a first state and a second state according to the linkage state of the first switch tube, the second switch tube, and the third switch tube. In the step-down mode, the second switch tube is always turned off, and the step-down mode is divided into a third state and a fourth state according to the linkage state of the first switch tube, the third switch tube, and the fourth switch tube.
在本公开的一种实施例中,当输入电压低于输出电压(VIN<VOUT)时,电路工作在升压模式。在升压模式时,第四开关管S4一直断开,S1、S2和S3交替导通,飞电容两端的电压VCF=VOUT-VIN。In one embodiment of the present disclosure, when the input voltage is lower than the output voltage (V IN <V OUT ), the circuit works in boost mode. In the boost mode, the fourth switch S 4 is always off, S 1 , S 2 and S 3 are turned on alternately, and the voltage across the flying capacitor V CF =V OUT -V IN .
更具体地,结合图6a、图7和图10所示,在升压模式的第一状态(0-DT)时间段内,S1导通,S2和S3断开,此时第一开关节点压值VSW1=VOUT-VIN,第二开关节点压值VSW2=0,VSW1小于输入电压VIN,电感两端压差大于0,电感充磁,电感电流上升,并向飞电容充电+ΔQ=ILDT,在这段时间内没有电荷从输入留到输出电容。More specifically, as shown in Fig. 6a, Fig. 7 and Fig. 10, during the time period of the first state (0-DT) of the boost mode, S 1 is turned on, and S 2 and S 3 are turned off. At this time, the first The switch node voltage value V SW1 = V OUT -V IN , the second switch node voltage value V SW2 = 0, V SW1 is less than the input voltage V IN , the voltage difference across the inductor is greater than 0, the inductor is magnetized, the inductor current rises, and goes to Flying capacitor charge + ΔQ = I L DT, during which time no charge is left from the input to the output capacitor.
更具体地,结合图6b、图7和图10所示,在第二状态(DT-T)时间段内,S1断开,S2和S3导通,此时第一开关节点压值VSW1=VOUT,VSW2=VIN,VSW1大于输入电压VIN,电感两端压差小于0,电感去磁,电感电流下降,此时飞电容放电,向输出电容COUT传输电荷。对电感做伏秒平衡,可得:More specifically, as shown in Fig. 6b, Fig. 7 and Fig. 10, in the second state (DT-T) time period, S 1 is off, S 2 and S 3 are on, at this time the first switch node voltage value V SW1 =V OUT , V SW2 =V IN ,
D(YIN-(VOUT-YIN))=(1-D)(VOUT-VIN) (9)D(Y IN -(V OUT -Y IN ))=(1-D)(V OUT -V IN ) (9)
其中,M为电压转换比,D为占空比,D∈(0,1),M∈(1,2),VIN为输入电压的压值,VOUT为输出电压的压值。Among them, M is the voltage conversion ratio, D is the duty cycle, D∈(0,1), M∈(1,2), V IN is the voltage value of the input voltage, and V OUT is the voltage value of the output voltage.
升压模式下,关键信号波形如图7所示,功率电感电流IL=IOUT,低于传统结构中的IL=MIOUT(M>1)。在升压模式时,功率电感电流等于负载电流;第一开关管S1,第二开关管S2,第三开关管S3选用最大耐压值为输入电压的开关管,第四开关管S4选用最大耐压值为输出电压的开关管,例如其中输入电压值的范围为2.5V-5V,输出电压值的范围为3.3±0.1V。In boost mode, the key signal waveform is shown in Figure 7, the power inductor current I L =I OUT is lower than I L =MI OUT in the traditional structure (M>1). In the boost mode, the power inductor current is equal to the load current; the first switching tube S 1 , the second switching tube S 2 , and the third switching tube S 3 select the switching tube whose maximum withstand voltage is the input voltage, and the fourth switching tube S 4 Select a switching tube whose maximum withstand voltage is the output voltage, for example, the range of the input voltage is 2.5V-5V, and the range of the output voltage is 3.3±0.1V.
在本公开的一种实施例中,当输入电压高于输出电压(VIN>VOUT)时,电路工作在降压模式,在降压模式时,S2一直断开,S1,S3和S4交替导通,飞电容两端的电压VCF=VOUT。In one embodiment of the present disclosure, when the input voltage is higher than the output voltage (V IN >V OUT ), the circuit works in buck mode, and in the buck mode, S 2 is always disconnected, S 1 , S 3 and S 4 are turned on alternately, and the voltage at both ends of the flying capacitor is V CF =V OUT .
更具体地,结合图8a、图9和图10所示,在降压模式的第三状态(0-DT)时间段内,S1,S3导通,S4断开,此时开关节点VSW1=VOUT,VSW2=0,VSW1小于输入电压VIN,电感两端压差大于0,电感充磁,电感电流上升,此时飞电容在放电,电荷流到输出电容Cout。More specifically, as shown in Fig. 8a, Fig. 9 and Fig. 10, during the time period of the third state (0-DT) of buck mode, S 1 and S 3 are turned on, and S 4 is turned off, at this time the switch node V SW1 = V OUT , V SW2 = 0, V SW1 is less than the input voltage V IN , the voltage difference across the inductor is greater than 0, the inductor is magnetized, and the inductor current rises. At this time, the flying capacitor is discharging, and the charge flows to the output capacitor Cout.
更具体地,结合图8b、图9和图10所示,在第四状态(DT-T)时间段内,S1,S3断开,S4导通,此时开关节点VSW1=2VOUT,VSW2=VOUT,VSW1大于输入电压VIN,电感两端压差小于0,电感去磁,电感电流下降,此时飞电容在充电,+ΔQ=ILDT。对电感做伏秒平衡,可得:More specifically, as shown in FIG. 8b , FIG. 9 and FIG. 10 , in the fourth state (DT-T) period, S 1 and S 3 are turned off, and S 4 is turned on. At this time, the switch node V SW1 =2V OUT , V SW2 = V OUT , V SW1 is greater than the input voltage V IN , the voltage difference across the inductor is less than 0, the inductor is demagnetized, the inductor current drops, and the flying capacitor is charging at this time, +ΔQ= IL DT. By doing volt-second balance on the inductor, we get:
D(VIN-VOUT)=(1-D)(2VOUT-VIN) (11)D(V IN -V OUT )=(1-D)(2V OUT -V IN ) (11)
其中,M为电压转换比,D为占空比,D∈(0,1),M∈(0.5,1),VIN为输入电压的压值,VOUT为输出电压的压值。Among them, M is the voltage conversion ratio, D is the duty cycle, D∈(0,1), M∈(0.5,1), V IN is the voltage value of the input voltage, and V OUT is the voltage value of the output voltage.
降压模式下,电路主要信号波形如图9所示,电感电流IL=MIOUT(M<1),低于传统结构中的IL=IOUT。在降压模式时,功率电感电流小于负载电流,第一开关管S1,第三开关管S3,第四开关管S4选用最大耐压值为输出电压的开关管,第二开关管S2选用最大耐压值为输入电压的开关管,例如其中输入电压值的范围为2.5V-5V,输出电压值的范围为3.3±0.1V。In step-down mode, the main signal waveform of the circuit is shown in Figure 9, the inductor current I L =MI OUT (M<1), which is lower than I L =I OUT in the traditional structure. In step-down mode, the power inductor current is smaller than the load current, the first switching tube S 1 , the third switching tube S 3 , and the fourth switching tube S 4 select the switching tube whose maximum withstand voltage is the output voltage, and the second switching tube S 2 Select a switching tube with a maximum withstand voltage value of the input voltage, for example, the range of the input voltage value is 2.5V-5V, and the range of the output voltage value is 3.3±0.1V.
至此,已经结合附图对本公开实施例进行了详细描述。需要说明的是,在附图或说明书正文中,未绘示或描述的实现方式,均为所属技术领域中普通技术人员所知的形式,并未进行详细说明。此外,上述对各元件和方法的定义并不仅限于实施例中提到的各种具体结构、形状或方式,本领域普通技术人员可对其进行简单地更改或替换。So far, the embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. It should be noted that, in the accompanying drawings or in the text of the specification, implementations that are not shown or described are forms known to those of ordinary skill in the art, and are not described in detail. In addition, the above definitions of each element and method are not limited to the various specific structures, shapes or methods mentioned in the embodiments, and those skilled in the art can easily modify or replace them.
依据以上描述,本领域技术人员应当对本公开具有飞电容的混合降压-升压直流-直流转换器有了清楚的认识。Based on the above description, those skilled in the art should have a clear understanding of the disclosed hybrid buck-boost DC-DC converter with flying capacitors.
综上所述,本公开提供了一种具有飞电容的混合降压-升压直流-直流转换器,在传统结构的4个功率管和1个功率管的基础上,引入1个飞电容,在所有的工作条件下降低电感电流的同时,功率管的导通损耗也大大降低,在保证系统高效率的前提下可大大减少芯片面积以及电感尺寸,芯片成本和体积都得到降低。To sum up, the present disclosure provides a hybrid buck-boost DC-DC converter with a flying capacitor. On the basis of the traditional structure of 4 power tubes and 1 power tube, a flying capacitor is introduced, While reducing the inductor current under all working conditions, the conduction loss of the power tube is also greatly reduced. On the premise of ensuring high system efficiency, the chip area and inductor size can be greatly reduced, and the chip cost and volume are reduced.
还需要说明的是,以上为本公开提供的不同实施例。这些实施例是用于说明本公开的技术内容,而非用于限制本公开的权利保护范围。一实施例的一特征可通过合适的修饰、置换、组合、分离以应用于其他实施例。It should also be noted that the above are different embodiments provided by the present disclosure. These embodiments are used to illustrate the technical content of the present disclosure, rather than to limit the protection scope of the present disclosure. A feature of one embodiment can be applied to other embodiments through appropriate modification, replacement, combination, and separation.
应注意的是,在本文中,除了特别指明的之外,具备“一”元件不限于具备单一的该元件,而可具备一或更多的该元件。It should be noted that, unless otherwise specified herein, having “a” element is not limited to having a single element, but may include one or more elements.
此外,在本文中,除了特别指明的之外,“第一”、“第二”等序数,只是用于区别具有相同名称的多个元件,并不表示它们之间存在位阶、层级、执行顺序、或制程顺序。一“第一”元件与一“第二”元件可能一起出现在同一构件中,或分别出现在不同构件中。序数较大的一元件的存在不必然表示序数较小的另一元件的存在。In addition, in this article, unless otherwise specified, ordinal numbers such as "first" and "second" are only used to distinguish multiple components with the same name, and do not indicate that there is a hierarchy, level, execution sequence, or process sequence. A "first" element and a "second" element may appear together in the same component, or may appear separately in different components. The presence of an element with a higher ordinal number does not necessarily indicate the presence of another element with a lower ordinal number.
在本文中,除了特别指明的之外,所谓的特征甲“或”(or)或“及/或”(and/or)特征乙,是指甲单独存在、乙单独存在、或甲与乙同时存在;所谓的特征甲“及”(and)或“与”(and)或“且”(and)特征乙,是指甲与乙同时存在;所谓的“包括”、“包含”、“具有”、“含有”,是指包括但不限于此。In this paper, unless otherwise specified, the so-called feature A "or" (or) or "and/or" (and/or) feature B means that nail exists alone, B exists alone, or A and B exist simultaneously ; The so-called feature A "and" (and) or "and" (and) or "and" (and) feature B means that nail and B exist at the same time; the so-called "includes", "includes", "has", " Contains" means including but not limited to.
此外,在本文中,所谓的“上”、“下”、“左”、“右”、“前”、“后”、或“之间”等用语,只是用于描述多个元件之间的相对位置,并在解释上可推广成包括平移、旋转、或镜像的情形。此外,在本文中,除了特别指明的之外,“一元件在另一元件上”或类似叙述不必然表示该元件接触该另一元件。In addition, in this article, the so-called "upper", "lower", "left", "right", "front", "rear", or "between" and other terms are only used to describe the distance between a plurality of elements. relative position, and can be generalized in interpretation to include cases of translation, rotation, or mirroring. In addition, herein, unless otherwise specified, "an element is on another element" or similar expressions do not necessarily mean that the element contacts the other element.
此外,除非特别描述或必须依序发生的步骤,上述步骤的顺序并无限制于以上所列,且可根据所需设计而变化或重新安排。并且上述实施例可基于设计及可靠度的考虑,彼此混合搭配使用或与其他实施例混合搭配使用,即不同实施例中的技术特征可以自由组合形成更多的实施例。In addition, unless specifically described or steps that must occur sequentially, the order of the above steps is not limited to that listed above and may be changed or rearranged according to the desired design. Moreover, the above-mentioned embodiments can be mixed and matched with each other or with other embodiments based on design and reliability considerations, that is, technical features in different embodiments can be freely combined to form more embodiments.
以上所述的具体实施例,对本公开的目的、技术方案和有益效果进行了进一步详细说明,所应理解的是,以上所述仅为本公开的具体实施例而已,并不用于限制本公开,凡在本公开的精神和原则之内,所做的任何修改、等同替换、改进等,均应包含在本公开的保护范围之内。The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present disclosure in detail. It should be understood that the above descriptions are only specific embodiments of the present disclosure, and are not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included within the protection scope of the present disclosure.
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