DC voltage conversion circuit with continuous output current and DC voltage conversion method

Abstract

The embodiments of the present invention provide a DC voltage conversion circuit and a DC voltage conversion method with continuous output current, which can be applied to the field of circuit technology. The circuit includes: a voltage regulating unit, including seven switches and two capacitors, wherein the first switch, the fifth switch, the second switch, the sixth switch, the third switch, and the fourth switch are connected in series in sequence, the first capacitor is connected in parallel to the series circuit of the fifth switch and the second switch, the second capacitor is connected in parallel to the series circuit of the second switch and the sixth switch, and the seventh switch is connected in parallel to the series circuit of the first switch, the fifth switch, and the second switch; the first end of the first switch and the first end of the seventh switch are connected to the power supply, the second end of the fifth switch and the first end of the second switch are connected to the first end of the inductor, and the second end of the fourth switch is connected to the ground. The DC voltage conversion circuit provided by the present invention can seamlessly adjust the output voltage, and the output voltage can be higher, equal to, or lower than the input voltage.

Description

Technical Field

[0001] The present invention relates to the field of circuit technology, and more specifically, to a DC voltage conversion circuit with continuous output current and a DC voltage conversion method. Background Art

[0002] Buck-boost converters, as a type of DC-DC converter, have a wide range of application backgrounds and technical developments in the current field of power electronics, and are particularly widely used in battery-powered mobile systems. Buck-boost converters can automatically adjust their operating modes according to load requirements and the actual output voltage of the battery, which not only ensures that mobile devices can still work stably when the battery voltage changes, but also improves battery efficiency and extends the battery life of the device.

[0003] Since the traditional single-mode buck-boost converter has high conduction loss, in order to reduce the conduction loss, it is usually necessary to increase the size of the power tube to reduce its on-resistance. However, large-sized and high-voltage power tubes will not only reduce chip efficiency, but also increase chip manufacturing costs. In addition, since the output current of the traditional single-mode buck-boost converter is discontinuous, the output ripple is large and there is a right half plane zero, which further limits the speed of its transient response. Summary of the invention

[0004] In view of this, the present invention provides a DC voltage conversion circuit and a DC voltage conversion method with continuous output current.

[0005] One aspect of the present invention provides a DC voltage conversion circuit with continuous output current, comprising: a voltage regulating unit, wherein the input end of the voltage regulating unit is connected to a power supply; an inductor, wherein the first end of the inductor is connected to the output end of the voltage regulating unit via a switch node, and the second end of the inductor is connected to a load; wherein the voltage regulating unit comprises a plurality of switches and a plurality of capacitors, and the voltage regulating unit is configured to control the conduction and cutoff of each of the plurality of switches in response to a clock signal to switch between a first working mode and a second working mode, so as to perform voltage regulation on the switch voltage at the switch node.

[0006] According to an embodiment of the present invention, the plurality of capacitors include a first capacitor and a second capacitor, and the plurality of switches include a first switch, a second switch, a third switch, a fourth switch, a fifth switch, a sixth switch, and a seventh switch; wherein the first switch, the fifth switch, the second switch, the sixth switch, the third switch, and the fourth switch are sequentially connected in series, the first capacitor is connected in parallel to a series circuit of the fifth switch and the second switch, the second capacitor is connected in parallel to a series circuit of the second switch and the sixth switch, and the seventh switch is connected in parallel to a series circuit of the first switch, the fifth switch, and the second switch; a first end of the first switch and a first end of the seventh switch are respectively connected to the power supply, a second end of the fifth switch and a first end of the second switch are respectively connected to a first end of the inductor, and a second end of the fourth switch is connected to a ground terminal.

[0007] According to an embodiment of the present invention, the voltage regulating unit is configured such that in the first working mode, the first switch, the second switch, the third switch and the fourth switch are turned on, the fifth switch, the sixth switch and the seventh switch are turned off, the input end of the first capacitor is connected to the power supply via the first switch, the output end of the first capacitor is connected to the input end of the second capacitor via the second switch, the output end of the second capacitor is connected to the ground via the third switch and the fourth switch, and the second end of the first capacitor and the first end of the second capacitor are respectively connected to the first end of the inductor.

[0008] According to an embodiment of the present invention, in the first working mode, the power supply charges the first capacitor and the second capacitor so that the first capacitor and the second capacitor provide a first voltage lower than the power supply voltage to the inductor, and the first voltage is less than the output voltage, and the inductor is demagnetized, so that the inductor current decreases.

[0009] According to an embodiment of the present invention, the voltage regulating unit is configured such that in the second working mode, the fifth switch, the sixth switch and the seventh switch are turned on, and the first switch, the second switch, the third switch and the fourth switch are turned off; the input end of the first capacitor is connected to the power supply via the seventh switch, the output end of the first capacitor is respectively connected to the first end of the inductor and the input end of the second capacitor via the fifth switch, and the output end of the second capacitor is connected to the power supply via the sixth switch and the seventh switch.

[0010] According to an embodiment of the present invention, in the second working mode, the first capacitor and the second capacitor discharge to the inductor so as to provide the inductor with a second voltage higher than the power supply voltage, and the second voltage is greater than the output voltage, and the inductor is magnetized, so that the inductor current increases.

[0011] According to an embodiment of the present invention, the duration of a first time period corresponding to the first working mode and the duration of a second time period corresponding to the second working mode are determined based on the duration of a switching cycle and the on-duty cycle of each of the above-mentioned multiple switches, wherein, when the duration of the above-mentioned first time period accounts for less than fifty percent, the above-mentioned output voltage is higher than the input voltage; when the duration of the above-mentioned first time period accounts for fifty percent, the above-mentioned output voltage is equal to the above-mentioned input voltage; when the duration of the above-mentioned first time period accounts for more than fifty percent, the above-mentioned output voltage is lower than the above-mentioned input voltage.

[0012] According to an embodiment of the present invention, the maximum withstand voltage value of the first switch, the second switch, the third switch, the fourth switch, the fifth switch, the sixth switch, and the seventh switch is half of the power supply voltage.

[0013] According to an embodiment of the present invention, the inductor is connected in series with the load to ensure that the current flowing through the load is a continuous inductor current, so that the voltage conversion circuit has no right half plane zero point.

[0014] Another aspect of the present invention provides a method for direct current voltage conversion with continuous output current, the method comprising: when the first switch, the second switch, the third switch and the fourth switch are turned on and the fifth switch, the sixth switch and the seventh switch are turned off, the first capacitor and the second capacitor provide the inductor with a first voltage lower than the power supply voltage; when the fifth switch, the sixth switch and the seventh switch are turned on and the first switch, the second switch, the third switch and the fourth switch are turned off, the first capacitor and the second capacitor provide the inductor with a second voltage higher than the power supply voltage.

[0015] According to the DC voltage conversion circuit with continuous output current provided by the embodiment of the present invention, multiple switches in the voltage regulating unit included in the circuit are alternately turned on in each switching cycle to switch the connection relationship between multiple capacitors, thereby forming different conduction paths, so that the circuit switches between the first working mode and the second working mode to flexibly adjust the output voltage. In addition, since the inductor is directly connected to the load at the output end, even if the circuit is in different working states, by switching the conduction and shutdown of multiple switches, at least one conduction path is included so that the inductor current flowing through the inductor can be continuous and uninterrupted, thereby ensuring the continuity of the output current, and there is no right half plane zero point. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0017] Figure 1 A circuit structure schematic diagram of a DC voltage conversion circuit according to an embodiment of the present invention is shown.

[0018] Figure 2 A circuit diagram of a DC voltage conversion circuit according to a specific embodiment of the present invention is shown.

[0019] Figure 3 A schematic diagram of an equivalent circuit of a DC voltage conversion circuit in a first working mode according to a specific embodiment of the present invention is shown.

[0020] Figure 4 A schematic diagram of an equivalent circuit of a DC voltage conversion circuit in a second working mode according to a specific embodiment of the present invention is shown.

[0021] Figure 5 A working state waveform diagram of a DC voltage conversion circuit according to a specific embodiment of the present invention is shown.

[0022] Figure 6 A flow chart of a DC voltage conversion method according to a specific embodiment of the present invention is shown.

[0023] Figure 7 A circuit schematic of a first basic voltage converter is shown.

[0024] Figure 8 FIG. 4 shows an equivalent circuit diagram of a first basic voltage converter in a first state.

[0025] Fig. 9 FIG. 4 shows an equivalent circuit diagram of the first basic voltage converter in the second state.

[0026] Fig.10 The working state waveform diagram of the first basic voltage converter is shown.

[0027] Fig.11 A circuit schematic of a second basic voltage converter is shown.

[0028] Fig.12 FIG. 4 shows an equivalent circuit diagram of a second basic voltage converter in a first state.

[0029] Fig.13 FIG. 4 shows an equivalent circuit diagram of the second basic voltage converter in the second state.

[0030] Fig.14 The working state waveform diagram of the second basic voltage converter is shown.

[0031] Fig.15 A circuit schematic of a third basic voltage converter is shown.

[0032] Fig.16 FIG. 4 shows an equivalent circuit diagram of a third basic voltage converter in a first state.

[0033] Fig.17 FIG. 4 shows an equivalent circuit diagram of the third basic voltage converter in the second state.

[0034] Fig.18 The working state waveform diagram of the third basic voltage converter is shown. DETAILED DESCRIPTION

[0035] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0036] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0037] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0038] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0039] Lithium batteries are usually used as the main power source for mobile devices due to their high energy density, high power density and rechargeable characteristics. Among them, 3.3V / 3.4V voltage is widely used in consumer electronic devices. However, as lithium batteries are used, their output voltage will gradually decrease from the initial fully charged state (such as 4.2V) to the discharge cut-off voltage (such as 2.5V). In order to cope with this change in battery voltage and ensure that mobile devices can operate stably throughout the battery life cycle, buck-boost converters with both buck and boost capabilities are widely used in battery-powered mobile systems.

[0040] The buck-boost converter can automatically adjust its operating mode according to the load demand and the actual output voltage of the battery. When the battery voltage is higher than the voltage required by the load, the converter works in buck mode and reduces the battery voltage to the voltage level required by the load. When the battery voltage is lower than the voltage required by the load, the converter switches to boost mode and meets the load demand by increasing the voltage. Therefore, in battery-powered mobile systems, the buck-boost converter plays a vital role. It not only ensures that mobile devices can still work stably when the battery voltage changes, but also improves the battery efficiency and extends the battery life of the device.

[0041] The traditional single-mode buck-boost converter is a cascade of a traditional boost converter and a traditional buck converter. This cascade method will always result in two power tubes in series with the inductor in the power path, while a separate boost or buck converter has only one power tube in series with the inductor. Therefore, compared with a separate boost or buck converter, the traditional single-mode buck-boost converter has higher conduction losses. In order to reduce the conduction loss, it is usually necessary to increase the size of the power tube to reduce its on-resistance. However, large-sized and high-voltage power tubes will not only reduce chip efficiency, but also increase the manufacturing cost of the chip. Secondly, since the output current of the traditional single-mode buck-boost converter is discontinuous, the output ripple is large, and there is a right half plane zero, which further limits the speed of its transient response. In addition, since the inductor current of the traditional single-mode buck-boost converter is very large, this will increase the DC resistance loss, thereby damaging the overall efficiency of the system.

[0042] Based on the above problems, an embodiment of the present invention provides a DC voltage conversion circuit with continuous output current and a DC voltage conversion method, wherein multiple switches in a voltage regulating unit included in the circuit are alternately turned on in each switching cycle to switch the connection relationship between multiple capacitors, thereby forming different conduction paths, so that the circuit switches between a first working mode and a second working mode to flexibly adjust the output voltage. In addition, since the inductor is directly connected to the load at the output end, even if the circuit is in different working states, by switching the conduction and disconnection of multiple switches, at least one conduction path is included so that the inductor current flowing through the inductor can be continuous and uninterrupted, thereby ensuring the continuity of the output current, and there is no right half plane zero point.

[0043] Specifically, an embodiment of the present invention provides a DC voltage conversion circuit with continuous output current, the circuit comprising: a voltage regulating unit, the input end of the voltage regulating unit is connected to a power supply; an inductor, the first end of the inductor is connected to the output end of the voltage regulating unit via a switch node, and the second end of the inductor is connected to a load; wherein the voltage regulating unit comprises a plurality of switches and a plurality of capacitors, and the voltage regulating unit is configured to control the conduction and shutdown of each of the plurality of switches in response to a clock signal to switch between a first working mode and a second working mode, so as to perform voltage regulation on the switch voltage at the switch node.

[0044] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0045] Figure 1 A circuit structure schematic diagram of a DC voltage conversion circuit according to an embodiment of the present invention is shown.

[0046] like Figure 1 As shown, the DC voltage conversion circuit may be a hybrid buck-boost DC-DC conversion circuit. The DC voltage conversion circuit includes a voltage regulating unit 110 , an inductor L and a load 120 .

[0047] The input end of the voltage regulating unit 110 is connected to the power supply and is used to receive the power supply voltage V IN The power supply may include any DC power supply. The output end of the voltage regulating unit 110 is connected to the first end of the inductor L via the switch node, so that the electric energy provided by the power supply flows into the inductor L via the output end of the voltage regulating unit 110. The second end of the inductor L is connected to the load 120 at the output end of the circuit via the output node, so that the electric energy stored in the inductor L flows to the load 120 via the second end of the inductor L, providing the required electric energy for the load 120.

[0048] The voltage regulating unit 110 includes a plurality of switches and a plurality of capacitors, wherein the plurality of switches may be power switches, and the plurality of switches may be implemented by, but not limited to, transistors. The plurality of capacitors may be flying capacitors, which may transfer charge between different capacitors by switching the plurality of switches, thereby changing the waveform or level of the output voltage.

[0049] The voltage regulating unit 110 is configured to control the on and off of each of the multiple switches in response to the clock signal, so that the DC voltage conversion circuit switches between the first working mode and the second working mode. In the first working mode, the multiple capacitors are electrically connected to the inductor L through the first conducting path, so as to provide the inductor L with a voltage lower than the power supply voltage V IN The first voltage.

[0050] The voltage regulating unit 110 may also be configured such that in the second working mode, the plurality of capacitors are electrically connected to the inductor L through the second conducting path, so as to provide the inductor L with a voltage higher than the power supply voltage V IN The second voltage.

[0051] Based on this, the embodiment of the present invention forms different conduction paths by switching the connection relationship between the multiple capacitors through the alternating conduction of the multiple switches in the voltage regulating unit included in the circuit in each switching cycle, so that the circuit switches between the first working mode and the second working mode to flexibly adjust the output voltage. In addition, since the inductor is directly connected to the load at the output end, even if the circuit is in different working states, by switching the conduction and shutdown of the multiple switches, at least one conduction path is included so that the inductor current flowing through the inductor can be continuous and uninterrupted, thereby ensuring the continuity of the output current, and there is no right half plane zero point.

[0052] Figure 2 A circuit diagram of a DC voltage conversion circuit according to a specific embodiment of the present invention is shown.

[0053] like Figure 2 As shown, the multiple switches in the voltage regulating unit 110 include a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, a fifth switch S5, a sixth switch S6, and a seventh switch S7. The multiple capacitors in the voltage regulating unit 110 include a first capacitor C F1 and the second capacitor C F2 .

[0054] The first switch S1, the fifth switch S5, the second switch S2, the sixth switch S6, the third switch S3 and the fourth switch S4 are connected in series in sequence, and the first end of the first switch S1 is connected to the power supply, and the second end of the fourth switch S4 is connected to the ground.

[0055] Among them, the first capacitor CF1 The second capacitor C is connected in parallel to both ends of the series circuit of the fifth switch S5 and the second switch S2. F2 The seventh switch S7 is connected in parallel to both ends of the series circuit of the second switch S2 and the sixth switch S6 , and is connected in parallel to both ends of the series circuit of the first switch S1 , the fifth switch S5 and the second switch S2 .

[0056] The first end of the seventh switch S7 is connected to the power supply, the second end of the fifth switch S5 and the first end of the second switch S2 are respectively connected to the first end of the inductor L, and the second end of the fourth switch S4 is connected to the ground.

[0057] like Figure 2 As shown, the circuit further includes an output capacitor C connected in parallel with the load 120. OUT , output capacitor C OUT The input end of is connected to the first end of the load 120 and the output end of the inductor L respectively, and the output capacitor C OUT The output terminal is connected to the ground terminal. The output capacitor C OUT It can be configured to receive the inductor voltage from the inductor L and filter the inductor voltage to reduce the voltage fluctuation across the load. In addition, when the current demand of the load 120 changes suddenly, the output capacitor C OUT Able to respond quickly and source or sink the required current to ensure system stability and protect loads from voltage fluctuations.

[0058] Reference below Figure 3~Figure 5 , combined with specific embodiments Figure 2 The DC voltage conversion circuit shown is further explained.

[0059] Figure 3 A schematic diagram of an equivalent circuit of a DC voltage conversion circuit in a first working mode according to a specific embodiment of the present invention is shown.

[0060] Figure 4 A schematic diagram of an equivalent circuit of a DC voltage conversion circuit in a second working mode according to a specific embodiment of the present invention is shown.

[0061] Figure 5 A working state waveform diagram of a DC voltage conversion circuit according to a specific embodiment of the present invention is shown.

[0062] like Figure 3 As shown, in the first working mode, the voltage regulating unit 110 is configured such that the first switch S1 , the second switch S2 , the third switch S3 and the fourth switch S4 are turned on, and the fifth switch S5 , the sixth switch S6 and the seventh switch S7 are turned off to form a first conduction path.

[0063] like Figure 3 As shown, the first capacitor C F1The input end of the first switch S1 is connected to the power supply, and the first capacitor C F1 The output end of the second capacitor C is connected to the second capacitor C through the second switch S2. F2 The input terminal, the second capacitor C F2 The output end of the first capacitor C is connected to the ground end through the third switch S3 and the fourth switch S4. F1 The second end of the second capacitor C F2 The first end of each of the first capacitor C is connected to the input end of the inductor L through the switch node a, so that in the first period of time, the first capacitor C F1 With the second capacitor C F2 The first capacitor C is connected in series via the power supply. F1 With the second capacitor C F2 The first capacitor C F1 With the second capacitor C F2 The capacitor voltage is the power supply voltage V IN half of the switching voltage V at the switching node a. SW =V IN / 2.

[0064] According to an embodiment of the present invention, the duration of the first time period corresponding to the first working mode can be determined according to the duration of the switching cycle and the on-duty ratio of each of the multiple switches. For example, the first time period can be a DT~T period, where D can represent the on-duty ratio of the switch in the DC voltage conversion circuit, and T can be the switching cycle of the switch in the DC voltage conversion circuit, where D is greater than 0 and less than 1. For example, in the case where the switch is implemented by a transistor, D can be the duty ratio of the control signal of the switch in the DC voltage conversion circuit.

[0065] like Figure 5 As shown, φ1 can represent the first time period, such as (DT~T) time period, the switch voltage V at the switch node a SW =V IN / 2, the switch voltage V SW The first capacitance C can be characterized F1 and the second capacitor C F2 Provide a voltage lower than the power supply voltage V to the inductor L IN The first voltage is less than the output voltage V OUT , inductor L demagnetization discharge, inductor current I L decline.

[0066] like Figure 4 As shown, in the second working mode, the voltage regulating unit 110 is configured such that the first switch S1 , the second switch S2 , the third switch S3 and the fourth switch S4 are turned off, and the fifth switch S5 , the sixth switch S6 and the seventh switch S7 are turned on to form a second conduction path.

[0067] like Figure 4 As shown, the first capacitor C F1 The input end of the seventh switch S7 is connected to the power supply, and the first capacitor C F1 The output end of the fifth switch S5 is connected to the first end of the inductor L and the second capacitor C F2 The input terminal, the second capacitor C F2 The output end of the first capacitor C is connected to the power supply through the sixth switch S6 and the seventh switch S7, so that in the second period F1 With the second capacitor C F2 is a parallel connection relationship, and through the first capacitor C F1 With the second capacitor C F2 Discharge the inductor L, so that the switch voltage V at the switch node a SW =3V IN / 2.

[0068] According to an embodiment of the present invention, the duration of the second time period corresponding to the second working mode can also be determined according to the duration of the switching cycle and the on-duty ratio of each of the multiple switches. The second time period can represent the time period other than the first time period in each switching cycle, for example, the second time period can be the 0~DT time period.

[0069] like Figure 5 As shown, φ2 can represent the second time period, such as the (0~DT) time period, and the switch voltage V at the switch node a SW =3V IN / 2, the switch voltage V SW The first capacitance C can be characterized F1 and the second capacitor C F2 Provide a voltage higher than the power supply voltage V to the inductor L IN The second voltage is less than the output voltage V OUT , inductor current I L rise.

[0070] According to a specific embodiment of the present invention, the ratio of the first time period and the second time period to each switching cycle determines the relationship between the output voltage and the input voltage. Specifically, when the duration of the first time period accounts for less than 50%, the output voltage is higher than the input voltage; when the duration of the first time period accounts for 50%, the output voltage is lower than the input voltage; when the duration of the first time period accounts for more than 50%, the output voltage is lower than the input voltage.

[0071] Based on this, within at least one switching cycle, the voltage conversion ratio of the DC voltage conversion circuit proposed in the embodiment of the present invention can be solved using the volt-second balance principle. Specifically, the voltage conversion ratio can be solved by the following formula.

[0072] (1);

[0073] (2);

[0074] Where M represents the voltage conversion ratio, D represents the duty cycle of the switch, and V IN Represents the power supply voltage, V OUT represents the output voltage, where D∈(0,1), M∈(0.5,1.5).

[0075] Based on this, it can be seen from formula (2) that the voltage conversion ratio of the DC voltage conversion circuit proposed in the embodiment of the present invention is in the interval (0.5, 1.5), and covers both step-down (M<1) and step-up (M>1) working states. Therefore, the DC voltage conversion circuit can be operated without changing the input voltage V IN The voltage is directly transferred in the case of a voltage regulator. Therefore, by controlling the on and off of multiple switches in the voltage regulator unit and the charging and discharging process of the capacitor in different time periods of at least one switching cycle, the output voltage is continuously adjusted, and the output voltage can be higher, equal to, or lower than the input voltage, thereby realizing the buck and boost functions simultaneously in one working mode without switching between the buck mode and the boost mode, reducing the fluctuation of the output voltage, avoiding the mode switching problem, simplifying the control of the circuit and greatly improving the reliability of the circuit. In addition, since the inductor always forms a direct series relationship with the load at the output end, it is ensured that the output current flowing through the load is a continuous inductor current. Therefore, the output current is continuous and there is no right half plane zero point through the switch switching of the voltage regulator unit, thereby improving the stability of the output voltage and the transient response speed of the circuit.

[0076] According to a specific embodiment of the present invention, Figure 3 As shown, in the first period, the switch voltage V at the switch node a SW =V IN / 2, the voltage drops across the first switch S1, the second switch S2, the third switch S3 and the fourth switch S4 can all be regarded as 0, and the voltage drops across the fifth switch S5, the sixth switch S6 and the seventh switch S7 are all V IN / 2. Figure 5 As shown, in the second period, the switch voltage V at the switch node a SW =3V IN / 2, the voltage drops across the first switch S1, the second switch S2, the third switch S3 and the fourth switch S4 are all V IN / 2, the voltage drops across the fifth switch S5, the sixth switch S6, and the seventh switch S7 can all be regarded as 0. Therefore, the maximum withstand voltage values ​​of the first switch S1, the second switch S2, the third switch S3, the fourth switch S4, the fifth switch S5, the sixth switch S6, and the seventh switch S7 are all half of the power supply voltage.

[0077] Based on this, in the DC voltage conversion circuit proposed in the present invention, when the switch voltage V at the switch node a is SW When the voltage changes, multiple capacitors in the voltage regulator unit are used to absorb and release energy during the switch switching process to balance the voltage difference between different nodes so that the maximum withstand voltage of all switches does not exceed V IN Therefore, switches with lower withstand voltage values ​​can be used in the DC voltage conversion circuit proposed by the present invention, so that these switches have lower on-resistance and faster switching speed, thereby reducing conduction loss and switching loss while reducing manufacturing costs.

[0078] Figure 6 A flow chart of a DC voltage conversion method according to a specific embodiment of the present invention is shown.

[0079] like Figure 6 As shown, the DC voltage conversion method of this specific embodiment includes operation S601 and operation S602.

[0080] In operation S601 , when the first switch, the second switch, the third switch and the fourth switch are turned on and the fifth switch, the sixth switch and the seventh switch are turned off, the first capacitor and the second capacitor provide a first voltage lower than the power supply voltage to the inductor.

[0081] For example, in the first time period, the first switch S1, the second switch S2, the third switch S3 and the fourth switch S4 are turned on, and the fifth switch S5, the sixth switch S6 and the seventh switch S7 are turned off, so that in the first time period, the first capacitor C F1 With the second capacitor C F2 At this time, the first capacitor C F1 With the second capacitor C F2 Charging is performed so that the switch voltage V at the switch node a SW =V IN / 2, and use it as the first voltage. The first capacitor C F1 and the second capacitor C F2 Provide a voltage lower than the power supply voltage V to the inductor L IN The first voltage is less than the output voltage V OUT , inductor L demagnetizes and discharges, inductor current I L decline.

[0082] In operation S602 , when the fifth switch, the sixth switch, and the seventh switch are turned on and the first switch, the second switch, the third switch, and the fourth switch are turned off, the first capacitor and the second capacitor provide a second voltage higher than the power supply voltage to the inductor.

[0083] For example, in the second period, the first switch S1, the second switch S2, the third switch S3 and the fourth switch S4 are turned off, and the fifth switch S5, the sixth switch S6 and the seventh switch S7 are turned on, so that the first capacitor C F1 With the second capacitor C F2 is a parallel connection relationship, and through the first capacitor C F1 With the second capacitor C F2 Discharge the inductor L, so that the switch voltage V at the switch node a SW =3V IN / 2, and use it as the second voltage. The first capacitor C F1 and the second capacitor C F2 Provide a voltage higher than the power supply voltage V to the inductor L IN The second voltage is greater than the output voltage V OUT , inductor current I L rise.

[0084] It should be noted that the present invention does not limit the execution order of the operations of the present invention. For example, in some embodiments, S601 may be executed first, and then S602. Alternatively, in some embodiments, S602 may be executed first, and then S601. The other processes of the present invention are similar, and will not be described in detail here.

[0085] It should be noted that the DC voltage conversion method with continuous output current in the embodiment of the present invention corresponds to the DC voltage conversion circuit with continuous output current in the embodiment of the present invention. The description of the DC voltage conversion method with continuous output current specifically refers to the DC voltage conversion circuit with continuous output current, which will not be repeated here.

[0086] Figure 7 A circuit schematic of a first basic voltage converter is shown.

[0087] like Figure 7 As shown, the first basic voltage converter includes four switch tubes, including a first switch tube S 11 , the second switch tube S 12 , the third switch tube S 13 , the fourth switch tube S 14 The first basic voltage converter also includes a first inductor L1, a first output capacitor C OUT1 , the first load resistor R OUT1 .

[0088] Figure 8 FIG. 4 shows an equivalent circuit diagram of a first basic voltage converter in a first state.

[0089] Fig. 9 FIG. 4 shows an equivalent circuit diagram of the first basic voltage converter in the second state.

[0090] like Figure 8 and Fig. 9 As shown, the converter includes two working states, state 1 and state 2, wherein the first period of the first basic voltage converter can represent the (0~DT) period, and the first period is state 1, and the second period of the first basic voltage converter can represent the (DT~T) period, and the second period is state 2. SW1 represents the first switch node voltage, V SW2 represents the second switch node voltage, V IN1 Represents the power supply voltage, V OUT1 Indicates the output voltage, I OUT1 Represents the first output current.

[0091] In state 1 of the first basic voltage converter, the first switch tube S 11 With the fourth switch tube S 14 The second switch tube S 12 With the third switch tube S 13 Shutdown, at this time, V SW1 =V IN1 , V SW2 =0,V SW1 >V SW2 , the first inductor L1 is magnetized, and the first inductor current increases.

[0092] In state 2 of the first basic voltage converter, the first switch tube S 11 With the fourth switch tube S 14 Turn off, the second switch tube S 12 The third switch tube S 13 At this time, V SW1 =0,V SW2 =V OUT1 , V SW1 <V SW2 , the first inductor L1 is demagnetized and the current of the first inductor decreases.

[0093] like Figure 8 and Fig. 9 As shown, the first basic voltage converter has two switches connected in series with the inductor in both operating states, and the conduction loss is greatly increased compared with the traditional buck and boost converters.

[0094] The voltage conversion ratio of the first basic voltage converter is solved by using the volt-second balance principle. Specifically, the voltage conversion ratio can be solved by the following formula.

[0095] (3);

[0096] (4);

[0097] Wherein, M1 represents the voltage conversion ratio of the first basic voltage converter, D1 represents the switch duty cycle of the first basic voltage converter, V IN1 Represents the power supply voltage, V OUT1 represents the output voltage, where D1∈(0,1) and M1∈(0,∞).

[0098] The average current of the first inductor L1 can be obtained by solving the following formula.

[0099] (5);

[0100] Among them, I L1 Represents the first inductor current, I OUT1 Represents the first output current.

[0101] Fig.10 The working state waveform diagram of the first basic voltage converter is shown.

[0102] like Fig.10 As shown, in the first basic voltage converter, the first inductor current I L1 Always higher than the first output current I OUT1 , which greatly increases the conduction loss of the system. In order to improve the efficiency of the system, the size of the power tube needs to be increased to reduce its on-resistance, but this will lead to an increase in chip cost. At the same time, in order to reduce the loss of the inductor, it is necessary to select an inductor with a smaller on-resistance (Directive Current Resistance, DCR), but inductors with lower DCR are often larger in size, which not only increases the production cost, but also leads to an increase in the size of the chip.

[0103] Fig.11 A circuit schematic of a second basic voltage converter is shown.

[0104] like Fig.11 As shown, the second basic voltage converter includes 8 switch tubes, including the fifth switch tube S 21 , the sixth switch tube S 22 , the seventh switch tube S 23 , the eighth switch tube S 24 , the ninth switch tube S 25 , the tenth switch tube S 26 , Eleventh switch tube S 27 , the twelfth switch tube S 28 The second basic voltage converter also includes a second inductor L2, a first flying capacitor C F21 , the second flying capacitor C F22 , the second output capacitor C OUT2 , the second load resistor R OUT2 .

[0105] Fig.12 FIG. 4 shows an equivalent circuit diagram of a second basic voltage converter in a first state.

[0106] Fig.13 FIG. 4 shows an equivalent circuit diagram of the second basic voltage converter in the second state.

[0107] like Fig.12 and Fig.13 As shown, the second basic voltage converter includes two working states, state 1 and state 2, wherein the first time period of the second basic voltage converter can represent the (0~DT) time period, and the first time period is state 1, and the second time period of the second basic voltage converter can represent the (DT~T) time period, and the second time period is state 2. SW3 represents the third switch node voltage, V IN2 Represents the power supply voltage, V OUT2 Indicates the output voltage, I OUT2 represents the second output current.

[0108] In state 1 of the second basic voltage converter, the fifth switch tube S 21 , the seventh switch tube S 23 , the ninth switch tube S 25 , Eleventh switch tube S 27 The sixth switch tube S is turned on. 22 , the eighth switch tube S 24 , the tenth switch tube S 26 , the twelfth switch tube S 28 Turn off, at this time, the first flying capacitor C F21 Charging, the second flying capacitor C F22 Discharge, the first flying capacitor C F21 The voltage V 21 =V IN2 , the second flying capacitor C F22 The voltage V 22 =2V IN2 -V OUT2 At this time, the third switch node voltage V SW3 =3V IN2 -V OUT2 , V SW3 >V OUT2 , the second inductor L2 is magnetized and the current of the second inductor increases.

[0109] In state 2 of the second basic voltage converter, the sixth switch tube S 22 , the eighth switch tube S 24 , the tenth switch tube S 26 , the twelfth switch tube S 28 The fifth switch tube S is turned on. 21, the seventh switch tube S 23 , the ninth switch tube S 25 , Eleventh switch tube S 27 Turn off, at this time, the first flying capacitor C F21 Discharge, the second flying capacitor C F22 Charging, first flying capacitor C F21 The voltage V 21 =V IN2 , the second flying capacitor C F22 The voltage V 22 =2V IN2 -V OUT2 At this time, the third switch node voltage V SW3 =0,V SW3 <V OUT2 , the second inductor L2 is demagnetized and the current of the second inductor decreases.

[0110] The voltage conversion ratio of the second basic voltage converter is solved by using the volt-second balance principle. Specifically, the voltage conversion ratio can be solved by the following formula.

[0111] (6);

[0112] (7);

[0113] Wherein, M2 represents the voltage conversion ratio of the second basic voltage converter, D2 represents the switch duty cycle of the second basic voltage converter, V IN2 Represents the power supply voltage, V OUT2 represents the output voltage, where D2∈(0,1), M2∈(0,1.5).

[0114] The average current of the second inductor L2 can be obtained by solving the following formula.

[0115] (8);

[0116] Among them, I L2 represents the second inductor current, I OUT2 represents the second output current.

[0117] Fig.14 The working state waveform diagram of the second basic voltage converter is shown.

[0118] like Fig.14 As shown, compared with the first basic voltage converter, the second basic voltage converter reduces the second inductor current I L2 , reducing the DCR loss of the second inductor L2, which is beneficial to improving efficiency. However, this structure still has redundant switch tubes in the series path with the second inductor L2, using a total of 8 switch tubes, and the ninth switch tube S25 The withstand voltage is 2V IN2 , the tenth switch tube S 26 The withstand voltage is 3V IN2 -V OUT2 , high-voltage power tubes must be used, which not only reduces the efficiency of the chip but also increases the manufacturing cost of the chip.

[0119] Fig.15 A circuit schematic of a third basic voltage converter is shown.

[0120] like Fig.15 As shown, the third basic voltage converter includes 6 switch tubes, each including a thirteenth switch tube S 31 , the fourteenth switch tube S 32 , the fifteenth switch tube S 33 , the sixteenth switch tube S 34 , Seventeenth switch tube S 35 , the eighteenth switch tube S 36 The third basic voltage converter further includes a third inductor L3, a third flying capacitor C F31 、The fourth flying capacitor C F32 , the third output capacitor C OUT3 , the third load resistor R OUT3 .

[0121] Fig.16 FIG. 4 shows an equivalent circuit diagram of a third basic voltage converter in a first state.

[0122] Fig.17 FIG. 4 shows an equivalent circuit diagram of the third basic voltage converter in the second state.

[0123] like Fig.16 and Fig.17 As shown, the converter includes two working states, state 1 and state 2, wherein the first period of the third basic voltage converter can represent the (0~DT) period, and the first period is state 1, and the second period of the third basic voltage converter can represent the (DT~T) period, and the second period is state 2. SW4 represents the fourth switch node voltage, V SW5 represents the fifth switch node voltage, V IN3 Represents the power supply voltage, V OUT3 Indicates the output voltage, I OUT3 Represents the third output current.

[0124] In state 1 of the third basic voltage converter, the fourteenth switch tube S 32 , the sixteenth switch tube S 34 , the eighteenth switch tube S 36 The thirteenth switch tube S is turned on. 31, the fifteenth switch tube S 33 , Seventeenth switch tube S 35 Turn off, at this time, for the left side of the third inductor L3, the third flying capacitor C F31 Discharging, the fourth switch node voltage V SW4 =V IN3 +V 31 =2V IN3 , where V 31 Represents the third flying capacitor C F31 Voltage. For the right side of the third inductor L3, the fourth flying capacitor C F32 Discharge, the fifth switch node voltage V SW5 =V OUT3 . V SW4 >V SW5 , the third inductor L3 is magnetized, and the current of the third inductor L3 increases.

[0125] In state 2 of the third basic voltage converter, the fourteenth switch tube S 32 , the sixteenth switch tube S 34 , the eighteenth switch tube S 36 Turn off, the thirteenth switch S 31 , the fifteenth switch tube S 33 , Seventeenth switch tube S 35 At this time, for the left side of the third inductor L3, the third flying capacitor C F31 Charging, the fourth switch node voltage V SW4 =V IN3 ; For the right side of the third inductor L3, the fourth flying capacitor C F32 Charging, the fifth switch node voltage V SW5 =V OUT3 +V 32 =2V OUT3 , where V 32 Represents the fourth flying capacitor C F32 Voltage. V SW4 <V SW5 , the third inductor L3 is demagnetized, and the current of the third inductor L3 decreases.

[0126] The voltage conversion ratio of the third basic voltage converter is solved by using the volt-second balance principle. Specifically, the voltage conversion ratio can be solved by the following formula.

[0127] (9);

[0128] (10);

[0129] Wherein, M3 represents the voltage conversion ratio of the third basic voltage converter, D3 represents the switch duty cycle of the third basic voltage converter, V IN3Represents the power supply voltage, V OUT3 represents the output voltage, where D3∈(0,1) and M3∈(0.5,2).

[0130] The average current of the third inductor L3 can be obtained by solving the following formula.

[0131] (11);

[0132] Among them, I L3 represents the third inductor current, I OUT3 Represents the third output current.

[0133] Fig.18 The working state waveform diagram of the third basic voltage converter is shown.

[0134] like Fig.18 As shown, compared with the first basic voltage converter, the third inductor current of the third basic voltage converter is reduced, the DCR loss of the third inductor is reduced, and the system's requirement for the size of the third inductor is reduced. In addition, the withstand voltage value of each switch tube in the third basic voltage converter structure is only the power supply V IN3 Or the output voltage V OUT3 Compared with the structure of the second basic voltage converter, the withstand voltage problem is avoided, the manufacturing cost can be saved and the efficiency is improved. However, the structure of the third basic voltage converter still has redundant switches on the third inductor series path, which limits the efficiency improvement, and there is a right half plane zero point, which greatly limits the speed of transient response.

[0135] Table 1

[0136]

[0137] Based on this, as shown in Table 1, compared with the first basic voltage converter, the second basic voltage converter and the third basic voltage converter, the single-mode hybrid buck-boost DC-DC conversion circuit with continuous output current proposed by the present invention further reduces the maximum withstand voltage value of each switch, and the maximum withstand voltage value of all switches is reduced to VIN / 2. Therefore, even if there are still two switches in the path connected in series with the inductor in the structure, since all low withstand voltage switches are used, not only the conduction loss of the switch tube is reduced, but also the switching loss can be reduced, which greatly improves the efficiency of the conversion circuit. In addition, the output current of this structure is continuous, there is no right half plane zero point, and the transient response of the circuit is faster. In addition, due to the reduction of the average current of the inductor, this structure can greatly reduce the chip area and the size of the inductor while ensuring the high efficiency of the system, reducing the volume and manufacturing cost of the chip. At the same time, under the premise of the same area, the on-resistance of the single-mode hybrid buck-boost DC-DC conversion circuit with continuous output current proposed by the present invention is at least reduced to 1 / 8. Since the power loss is proportional to the on-resistance, the structure can achieve a significant efficiency improvement under the condition of the same chip area.

[0138] So far, the embodiments of the present invention have been described in detail in conjunction with the accompanying drawings. It should be noted that the implementation methods not shown or described in the drawings or the body of the specification are all forms known to ordinary technicians in the relevant technical field 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 ordinary technicians in the field can simply change or replace them.

[0139] Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in understanding the present invention.

[0140] Moreover, the shapes and sizes of the components in the figures do not reflect the real size and proportion, but only illustrate the contents of the embodiments of the present invention. In addition, in the claims, any reference symbols between brackets shall not be construed as limiting the claims.

[0141] Unless otherwise indicated, the numerical parameters in this specification and the appended claims are approximate values ​​and can vary according to the desired properties obtained through the content of the present invention. In particular, all numbers used in the specification and claims to express the content of the composition, reaction conditions, etc., should be understood to be modified by the term "about" in all cases. Furthermore, the word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0142] The ordinal numbers used in the specification and claims, such as "first", "second", "third", etc., to modify the corresponding elements, do not themselves mean that the elements have any ordinal numbers, nor do they represent the order of one element and another element, or the order in the manufacturing method. The use of these ordinal numbers is only used to clearly distinguish a component with a certain name from another component with the same name.

[0143] It will be appreciated by those skilled in the art that the features described in the various embodiments of the present invention may be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, without departing from the spirit and teachings of the present invention, the features described in the various embodiments of the present invention may be combined and / or combined in various ways. All of these combinations and / or combinations fall within the scope of the present invention.

[0144] The embodiments of the present invention are described above. However, these embodiments are only for the purpose of illustration, and are not intended to limit the scope of the present invention. Although each embodiment is described above, it does not mean that the measures in each embodiment cannot be used in combination advantageously. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A DC voltage conversion circuit with continuous output current, characterized in that: The circuit comprises: A voltage regulating unit, wherein an input end of the voltage regulating unit is connected to a power source; an inductor, wherein a first end of the inductor is connected to an output end of the voltage regulating unit via a switch node, and a second end of the inductor is connected to a load; The voltage regulating unit includes a plurality of switches and a plurality of capacitors, and the voltage regulating unit is configured to control the on and off of each of the plurality of switches in response to a clock signal to switch between a first working mode and a second working mode, so as to regulate the switch voltage at the switch node; The plurality of capacitors include a first capacitor and a second capacitor, and the plurality of switches include a first switch, a second switch, a third switch, a fourth switch, a fifth switch, a sixth switch, and a seventh switch; The first switch, the fifth switch, the second switch, the sixth switch, the third switch, and the fourth switch are connected in series in sequence, the first capacitor is connected in parallel to the series circuit of the fifth switch and the second switch, the second capacitor is connected in parallel to the series circuit of the second switch and the sixth switch, and the seventh switch is connected in parallel to the series circuit of the first switch, the fifth switch, and the second switch; The first end of the first switch and the first end of the seventh switch are respectively connected to the power supply, the second end of the fifth switch and the first end of the second switch are respectively connected to the first end of the inductor, and the second end of the fourth switch is connected to the ground.

2. The circuit according to claim 1, characterized in that The voltage regulating unit is configured such that, in the first working mode, the first switch, the second switch, the third switch, and the fourth switch are turned on, the fifth switch, the sixth switch, and the seventh switch are turned off, the input end of the first capacitor is connected to the power supply via the first switch, the output end of the first capacitor is connected to the input end of the second capacitor via the second switch, the output end of the second capacitor is connected to the ground via the third switch and the fourth switch, and the second end of the first capacitor and the first end of the second capacitor are respectively connected to the first end of the inductor.

3. The circuit according to claim 2, characterized in that In the first working mode, the power supply charges the first capacitor and the second capacitor so that the first capacitor and the second capacitor provide a first voltage lower than the power supply voltage to the inductor, and the first voltage is less than the output voltage, and the inductor is demagnetized, causing the inductor current to decrease.

4. The circuit according to claim 3, characterized in that The voltage regulating unit is configured such that in the second working mode, the fifth switch, the sixth switch, and the seventh switch are turned on, and the first switch, the second switch, the third switch, and the fourth switch are turned off; the input end of the first capacitor is connected to the power supply via the seventh switch, the output end of the first capacitor is respectively connected to the first end of the inductor and the input end of the second capacitor via the fifth switch, and the output end of the second capacitor is connected to the power supply via the sixth switch and the seventh switch.

5. The circuit according to claim 4, characterized in that In the second working mode, the first capacitor and the second capacitor discharge to the inductor to provide the inductor with a second voltage higher than the power supply voltage, and the second voltage is greater than the output voltage, and the inductor is magnetized, so that the inductor current increases.

6. The circuit according to claim 5, characterized in that The duration of a first time period corresponding to the first working mode and the duration of a second time period corresponding to the second working mode are determined based on the duration of a switching cycle and the on-duty cycle of each of the multiple switches, wherein, when the duration of the first time period accounts for less than fifty percent, the output voltage is higher than the input voltage; when the duration of the first time period accounts for fifty percent, the output voltage is equal to the input voltage; when the duration of the first time period accounts for more than fifty percent, the output voltage is lower than the input voltage.

7. The circuit according to any one of claims 2 to 6, characterized in that: The maximum withstand voltage value of the first switch, the second switch, the third switch, the fourth switch, the fifth switch, the sixth switch, and the seventh switch is half of the power supply voltage.

8. The circuit according to claim 6, characterized in that The inductor is connected in series with the load to ensure that the current flowing through the load is a continuous inductor current, so that the voltage conversion circuit has no right half plane zero point.

9. A method for converting a DC voltage with continuous output current, applied to the circuit described in any one of claims 1 to 8, characterized in that: The method comprises: When the first switch, the second switch, the third switch and the fourth switch are turned on and the fifth switch, the sixth switch and the seventh switch are turned off, the first capacitor and the second capacitor provide a first voltage lower than the power supply voltage to the inductor; When the fifth switch, the sixth switch, and the seventh switch are turned on and the first switch, the second switch, the third switch, and the fourth switch are turned off, the first capacitor and the second capacitor provide the inductor with a second voltage higher than the power supply voltage.

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