WO2023274236A1 - Voltage conversion circuit and electronic device - Google Patents

Abstract

The present application relates to the field of voltage conversion. Disclosed are a voltage conversion circuit and an electronic device, for use in realizing the same output current of each phase of three-level buck circuit of a multi-phase three-level buck circuit without using a current sharing loop, thereby reducing the implementation difficulty. The voltage conversion circuit comprises an N-phase three-level buck circuit; each phase of three-level buck circuit comprises a first inductor, a first capacitor, and a first switch transistor, a second switch transistor, a third switch transistor, and a fourth switch transistor that are sequentially connected in series; the first switch transistor is used for inputting power supply voltage, and the fourth switch transistor is grounded; a first end of the first inductor is coupled between the second switch transistor and the third switch transistor, and a second end of the first inductor is coupled to the output end of the voltage conversion circuit; a first end of the first capacitor of the previous phase is coupled between the first switch transistor and the second switch transistor of the previous phase; a second end of the first capacitor of the previous phase is coupled between the third switch transistor and the fourth switch transistor of the next phase.

Description

Voltage conversion circuits and electronic equipment

This application claims the priority of a Chinese patent application filed with the State Intellectual Property Office on June 30, 2021, with application number 202121483426.9, and application title "Voltage Transformation Circuit and Electronic Equipment", the entire contents of which are hereby incorporated by reference in this application .

technical field

The present application relates to the field of voltage conversion, in particular to a voltage conversion circuit and electronic equipment.

Background technique

Electronic equipment usually needs to be provided with a voltage conversion circuit to perform DC-DC voltage conversion, such as step-up or step-down. At present, the step-down (buck) circuit includes a two-level step-down circuit and a three-level step-down circuit. Compared with a two-level step-down circuit, a three-level step-down circuit has a smaller inductor current ripple and lower withstand voltage requirements. LCCs are smaller in size and more efficient. However, when multi-phase three-level step-down circuits are connected in parallel, it is necessary to ensure that the output current of each phase three-level step-down circuit is the same. Sexual risk, but the current sharing loop used to ensure the same output current is very complicated. It is necessary to consider avoiding mutual interference and common mode caused by multi-phase three-level step-down circuits, which greatly improves the realization difficulty.

Utility model content

Embodiments of the present application provide a voltage conversion circuit and electronic equipment, which are used to implement a multi-phase three-level step-down circuit without using a current sharing loop. The output current of each phase of the three-level step-down circuit is the same, thereby reducing the difficulty of implementation.

In order to achieve the above object, the embodiments of the present application adopt the following technical solutions:

In the first aspect, a voltage conversion circuit is provided, including an N-phase three-level step-down circuit, and each phase of the three-level step-down circuit in the N-phase three-level step-down circuit includes a first inductor, a first capacitor, and sequentially The first switching tube, the second switching tube, the third switching tube and the fourth switching tube are connected in series; the first switching tube inputs the power supply voltage, and the fourth switching tube is grounded; the first end of the first inductor is coupled to the second switching tube and the Between the third switching tubes, the second end of the first inductor is coupled to the output end of the voltage conversion circuit; in the N-phase three-level step-down circuit, the first end of the first capacitor of the previous phase three-level step-down circuit The terminal is coupled between the first switch tube and the second switch tube of the previous phase three-level step-down circuit; the second terminal of the first capacitor of the previous phase three-level step-down circuit is coupled to the next phase three-level Between the third switch tube and the fourth switch tube of the step-down circuit; wherein, the N-phase three-level step-down circuit after the N-phase three-level step-down circuit in the N-phase three-level step-down circuit refers to the N-phase In the first-phase three-level step-down circuit in the three-level step-down circuit, N is an integer greater than 1.

In the voltage conversion circuit provided in the embodiment of the present application, the first capacitor of the previous phase three-level step-down circuit can be coupled to the latter phase three-level step-down circuit through the third switch tube of the latter phase three-level step-down circuit The first inductance of the first phase of the three-level step-down circuit is connected to the power supply voltage for charging through the first switch tube of the previous phase three-level step-down circuit, so that the average charging current of the first capacitor of the previous phase three-level step-down circuit is equal to that of the latter The excitation current of the first inductor of the three-phase step-down circuit; the first capacitor of the previous three-level step-down circuit can also be coupled to the previous phase through the second switch tube of the previous three-level step-down circuit The first inductance of the three-level step-down circuit is grounded and discharged through the fourth switching tube of the next three-level step-down circuit, so that the average discharge current of the first capacitor of the previous three-level step-down circuit is equal to the previous The excitation current of the first inductor of the one-phase three-level step-down circuit. Since the charging charge of the previous phase three-level step-down circuit is equal to the discharge charge, the excitation current of the first inductor of the previous phase three-level step-down circuit is equal to the excitation current of the first inductor of the latter phase three-level step-down circuit current, and one end of the three-level step-down circuit of each phase is the output end of the three-level step-down circuit of the phase, so that the output current of the three-level step-down circuit of each phase is also equal, which reduces the difficulty of realizing the entire voltage conversion circuit.

It should be noted that in each phase of the three-level step-down circuit, more devices (such as other switch tubes) can be coupled between the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube, so The first switch tube, the second switch tube, the third switch tube and the fourth switch tube are not limited to four switch tubes coupled continuously, or in other words, the first switch tube, the second switch tube, the third switch tube and the fourth switch tube The four switch tubes are not limited to four switch tubes that are continuously coupled among multiple (more than four) coupled switch tubes, as long as the first switch tube, the second switch tube, the third switch tube and the fourth switch tube and These devices can realize the coupling relationship between the first capacitance of the previous three-level step-down circuit and the first inductance of the previous three-level step-down circuit or the first inductance of the next three-level step-down circuit That's it.

In a possible implementation manner, a control circuit is further included, and the control circuit is used to control the first switch tube and the second switch tube of the previous phase three-level step-down circuit and the first switch tube of the next phase three-level step-down circuit. The three switching tubes and the fourth switching tube switch between the first state, the second state or the third state; wherein, the first state makes the first capacitor of the previous phase three-level step-down circuit coupled to the next phase three-voltage Level the first inductance of the step-down circuit, and charge the first capacitor of the previous phase three-level step-down circuit; the second state makes the first capacitor of the previous phase three-level step-down circuit coupled to the previous phase three-level step-down circuit The first inductance of the level step-down circuit is discharged, and the first capacitor is discharged; the third state demagnetizes the first inductor of the next-phase three-level step-down circuit to ground. Since the first capacitor of the previous phase three-level step-down circuit is charged by the first inductor of the next phase three-level step-down circuit and discharged by the first inductor of the previous phase three-level step-down circuit, and the previous phase The average charging current of the first capacitor of the three-level step-down circuit is equal to the average discharge current, so the excitation current of the first inductor of the previous three-level step-down circuit (the output current of the previous three-level step-down circuit) is equal to The exciting current of the first inductor of the latter three-level step-down circuit (the output current of the latter three-level step-down circuit). In this way, the output current of each phase of the multi-phase three-level step-down circuit of the multi-phase three-level step-down circuit is the same (that is, the current is equalized), and the implementation difficulty of the entire voltage conversion circuit is reduced. The first state, the third state, the second state, and the third state are repeated periodically. After the first inductor is excited in the first state or the second state each time, it must be demagnetized through the third state.

In a possible implementation manner, in the first state, the control circuit is used to control the first switch tube of the previous phase three-level step-down circuit and the third switch tube of the next phase three-level step-down circuit to be turned on. , controlling the second switch tube of the previous phase three-level step-down circuit and the fourth switch tube of the next phase three-level step-down circuit to be turned off. At this time, the first capacitor of the previous phase three-level step-down circuit is charged by the first inductor of the next phase three-level step-down circuit, and the average charging current of the first capacitor of the previous phase three-level step-down circuit It is equal to the excitation current of the first inductor of the next-phase three-level step-down circuit.

In a possible implementation manner, in the second state, the control circuit is used to control the first switch tube of the previous phase three-level step-down circuit and the third switch tube of the next phase three-level step-down circuit to turn off. turn off, and control the second switch tube of the previous phase three-level step-down circuit and the fourth switch tube of the next phase three-level step-down circuit to turn on. At this time, the first capacitor of the previous phase three-level step-down circuit discharges through the first inductor of the previous phase three-level step-down circuit, and the average discharge current of the first capacitor of the previous phase three-level step-down circuit It is equal to the excitation current of the first inductor of the previous phase three-level step-down circuit.

In a possible implementation manner, in the third state, the control circuit is used to control the conduction of the third switch tube and the fourth switch tube of the next phase three-level step-down circuit, and control the conduction of the previous phase three-level step-down circuit. The first switch tube and the second switch tube of the voltage circuit are turned off. At this time, the first inductor of the next-phase three-level step-down circuit is grounded and demagnetized.

In a possible implementation manner, the control circuit is further configured to: if the voltage of the first capacitor of the previous phase three-level step-down circuit is greater than the first target value, reduce the ratio of the first state (that is, reduce the charging time of a capacitor) or increase the ratio of the second state (that is, increase the discharge time of the first capacitor); if the voltage of the first capacitor of the previous phase three-level step-down circuit is less than the second target value, increase Increase the ratio of the first state (that is, increase the charging time of the first capacitor) or reduce the ratio of the second state (that is, reduce the discharge time of the first capacitor), the first target value is greater than or equal to the second target value, for example Both can be half of the input voltage. Wherein, the ratio of the first state refers to the time of the first state/(the time of the first state+the time of the second state+the time of the third state). The ratio of the second state refers to the time of the second state/(the time of the first state+the time of the second state+the time of the third state).

In the second aspect, a control method of a voltage conversion circuit is provided, including: controlling the first switch tube and the second switch tube of the previous phase three-level step-down circuit and the third switch tube of the next phase three-level step-down circuit The switch tube and the fourth switch tube switch between the first state, the second state or the third state; wherein, the first state makes the first capacitor of the previous phase three-level step-down circuit coupled to the next phase three-level The first inductance of the step-down circuit, and charges the first capacitor of the previous phase three-level step-down circuit; the second state makes the first capacitor of the previous phase three-level step-down circuit coupled to the previous phase three-voltage level the first inductance of the step-down circuit, and discharge the first capacitor; the third state grounds the first inductance of the next-phase three-level step-down circuit to demagnetize.

In a possible implementation manner, control the first switch tube and the second switch tube of the previous phase three-level step-down circuit and the third switch tube and the fourth switch tube of the next phase three-level step-down circuit Switching among the first state, the second state or the third state includes: in the first state, controlling the first switching tube of the previous phase three-level step-down circuit and the third switch tube of the next phase three-level step-down circuit The switch tube is turned on, and the second switch tube of the previous phase three-level step-down circuit and the fourth switch tube of the next phase three-level step-down circuit are controlled to be turned off.

In a possible implementation manner, control the first switch tube and the second switch tube of the previous phase three-level step-down circuit and the third switch tube and the fourth switch tube of the next phase three-level step-down circuit Switching among the first state, the second state or the third state includes: in the second state, controlling the first switching tube of the previous phase three-level step-down circuit and the first switch tube of the next phase three-level step-down circuit The three switch tubes are turned off, and the second switch tube of the previous phase three-level step-down circuit and the fourth switch tube of the next phase three-level step-down circuit are controlled to be turned on.

In a possible implementation manner, control the first switch tube and the second switch tube of the previous phase three-level step-down circuit and the third switch tube and the fourth switch tube of the next phase three-level step-down circuit Switching between the first state, the second state, or the third state includes: in the third state, controlling the conduction of the third switching tube and the fourth switching tube of the next-phase three-level step-down circuit, and controlling the conduction of the previous phase The first switching tube and the second switching tube of the three-level step-down circuit are turned off.

In a possible implementation manner, it further includes: if the voltage of the first capacitor of the previous phase three-level step-down circuit is greater than the first target value, reducing the proportion of the first state or increasing the proportion of the second state ; If the voltage of the first capacitor of the previous phase three-level step-down circuit is less than the second target value, then increase the proportion of the first state or decrease the proportion of the second state, the first target value is greater than or equal to the second target value.

In a third aspect, an electronic device is provided, including the voltage conversion circuit and the working circuit according to the first aspect and any implementation manner thereof, and the voltage conversion circuit is used to supply power to the working circuit.

In a fourth aspect, there is provided a computer-readable storage medium, where instructions are stored in the computer-readable storage medium, and the instructions run on the electronic device, so that the electronic device executes the control method described in the second aspect and any implementation thereof .

According to a fifth aspect, a computer program product including instructions is provided, and the instructions run on an electronic device, so that the electronic device executes the control method described in the second aspect and any implementation manner thereof.

Regarding the technical effects of the second aspect to the fifth aspect, refer to the technical effects of the first aspect and any implementation thereof.

Description of drawings

FIG. 1 is a schematic structural diagram of an electronic device provided in an embodiment of the present application;

FIG. 2 is a schematic structural diagram of a two-level step-down circuit provided by an embodiment of the present application;

FIG. 3 is a schematic diagram of a waveform of a two-level step-down circuit provided by an embodiment of the present application;

FIG. 4 is a structural schematic diagram 1 of a three-level step-down circuit provided by an embodiment of the present application;

FIG. 5 is a schematic diagram of a waveform of a three-level step-down circuit provided by an embodiment of the present application;

FIG. 6 is a schematic structural diagram II of a three-level step-down circuit provided by an embodiment of the present application;

FIG. 7A is a schematic structural diagram of a voltage conversion circuit provided by an embodiment of the present application;

FIG. 7B is a schematic structural diagram of another voltage conversion circuit provided by the embodiment of the present application;

FIG. 8 is a first schematic diagram of a current path of a voltage conversion circuit provided by an embodiment of the present application;

FIG. 9 is a second schematic diagram of a current path of a voltage conversion circuit provided in an embodiment of the present application;

FIG. 10 is a schematic diagram 3 of a current path of a voltage conversion circuit provided in an embodiment of the present application;

FIG. 11 is a waveform schematic diagram 1 of a voltage conversion circuit provided by an embodiment of the present application;

FIG. 12 is a schematic diagram 4 of a current path of a voltage conversion circuit provided by an embodiment of the present application;

FIG. 13 is a schematic diagram 5 of a current path of a voltage conversion circuit provided in an embodiment of the present application;

FIG. 14 is a sixth schematic diagram of a current path of a voltage conversion circuit provided by an embodiment of the present application;

FIG. 15 is a second waveform schematic diagram of a voltage conversion circuit provided by an embodiment of the present application;

FIG. 16 is a schematic diagram 7 of a current path of a voltage conversion circuit provided by an embodiment of the present application;

FIG. 17 is a schematic diagram eighth of a current path of a voltage conversion circuit provided by an embodiment of the present application;

FIG. 18 is a schematic diagram 9 of a current path of a voltage conversion circuit provided by an embodiment of the present application;

FIG. 19 is a third waveform schematic diagram of a voltage conversion circuit provided by an embodiment of the present application.

detailed description

The voltage conversion circuit provided in the embodiment of the present application can be applied to electronic equipment.

As shown in FIG. 1 , an embodiment of the present application provides an electronic device. The electronic device 12 includes a battery charging chip 121 , a working circuit 122 and a battery 123 . The charging chip 121 may include a voltage conversion circuit 1211 . When charging, the power adapter 11 converts the mains power into direct current through AC-DC conversion, and the charging chip 121 supplies power to the battery 123; Wherein, the working circuit 122 includes a processor, a memory, a communication interface, etc., which are not limited in this application.

It should be noted that the voltage conversion circuit involved in the present application can not only be integrated in the charging chip 121 , but can also directly supply power to the working circuit 122 in the form of an independent circuit. Wherein, the voltage conversion circuit 1211 may include a buck circuit, a boost circuit, a buck-boost circuit, and the like. This application describes several commonly used step-down (buck) circuits.

As shown in FIG. 2 , a two-level step-down circuit is shown. The step-down circuit includes a MOS transistor Q1, a MOS transistor Q2, an inductor L, a capacitor C, and a NOT gate. The drain (drain, D) pole of the MOS transistor Q1 is used to input the power supply voltage Vin, the source (source, S) pole of the MOS transistor Q1 and the drain of the MOS transistor Q2 are coupled to the first end of the inductor L, and the second end of the inductor L Coupled to the first end of the capacitor C, the second end of the capacitor C and the source of the MOS transistor Q2 are grounded. The control signal Ctrl is input to the gate (gate, G) of the MOS transistor Q1 and the input terminal of the NOT gate, and the output terminal of the NOT gate is coupled to the gate of the MOS transistor Q2. Both ends of the capacitor C are used for the output voltage Vout.

The waveform of the step-down circuit is shown in Figure 3. When the control signal Ctrl is at a high level, the MOS transistor Q1 is turned on, the MOS transistor Q2 is turned off, the power supply voltage Vin excites the inductor L and charges the first capacitor C1, the current flowing through the inductor L increases linearly, and the first capacitor of the inductor L The voltage at terminal A is a positive voltage equal to the supply voltage Vin. When the control signal Ctrl is at a low level, the MOS transistor Q1 is turned off, the MOS transistor Q2 is turned on, the inductor L is demagnetized and the capacitor C is discharged, the current flowing through the inductor L decreases linearly, and the voltage at the first terminal A of the inductor L is negative. Voltage, the output voltage Vout is maintained by the discharge of the capacitor C and the inductor L. It can be seen that the voltage at the first terminal A of the inductor L has two levels of positive voltage and negative voltage, so the step-down circuit is called a two-level step-down circuit. By adjusting the duty cycle of the control signal Ctrl switching between high level and low level, the output voltage Vout can be adjusted.

As shown in Figure 4, a three-level step-down circuit is shown. Compared with the above-mentioned two-level step-down circuit, the inductor current ripple of the three-level step-down circuit is small, the withstand voltage requirement is lower, and the size of the inductor and capacitor Smaller and more efficient. The step-down circuit includes a voltage equalizing loop 41, a MOS transistor Q1, a MOS transistor Q2, a MOS transistor Q3, a MOS transistor Q4, an inductor L, a first capacitor C1, an output capacitor Cout, a NOT gate NOT1, and a NOT gate NOT2, wherein the first A capacitor C1 can also be called a flying capacitor. The drain of the MOS transistor Q1 is used to input the power supply voltage Vin, the source of the MOS transistor Q1 and the drain of the MOS transistor Q2 are coupled to the first end of the first capacitor C1, the source of the MOS transistor Q2 and the drain of the MOS transistor Q3 coupled to the first end of the inductor L, the source of the MOS transistor Q3 and the drain of the MOS transistor Q4 are coupled to the second end of the first capacitor C1, the second end of the inductor L is coupled to the first end of the output capacitor Cout, and the output The second end of the capacitor Cout and the source of the MOS transistor Q4 are grounded. The control signal Ctrl1 is input to the gate of the MOS transistor Q1 and the input terminal of the NOT gate NOT1, the output terminal of the NOT gate NOT1 is coupled to the gate of the MOS transistor Q4, the control signal Ctrl2 is input to the gate of the MOS transistor Q2 and the gate of the NOT gate NOT2 The input terminal and the output terminal of the NOT gate NOT2 are coupled to the gate of the MOS transistor Q3. Both ends of the output capacitor Cout are used for the output voltage Vout. It can be seen that the voltage at the first terminal A of the inductor L has three levels of Vin-Vc, Vc and 0, so the step-down circuit is called a three-level step-down circuit.

The waveform of the step-down circuit is shown in Figure 5. When the control signal Ctrl1 is at a high level and the control signal Ctrl2 is at a low level, the MOS transistor Q1 and the MOS transistor Q3 are turned on, the MOS transistor Q2 and the MOS transistor Q4 are turned off, and the power supply voltage Vin is charged to the first capacitor C1 and then to the first The inductor L1 is excited, the current flowing through the inductor L increases linearly, and the voltage at the first end A of the inductor L is Vin-Vc, wherein, Vc is the voltage of the first capacitor C1. When the control signal Ctrl1 and the control signal Ctrl2 are both low level, the MOS transistor Q3 and the MOS transistor Q4 are turned on, the voltage at the first end A of the inductor L is 0, and the inductor L is demagnetized; when the control signal Ctrl1 is low level and When the control signal Ctrl2 is at a high level, the MOS transistor Q2 and the MOS transistor Q4 are turned on, the first capacitor C1 is discharged, the voltage at the first terminal A of the inductor L is Vc, and the inductor L is demagnetized.

During the working process of the circuit, the voltage Vc of the first capacitor C1 can be kept at Vin/2, so that the turn-off voltage drop of the MOS tube is Vin/2, so that a MOS tube with a lower withstand voltage can be selected to reduce costs and The area occupied by the circuit, when the turn-off voltage drop of the MOS tube is other voltage values, it is necessary to select a MOS tube with a higher withstand voltage, which increases the cost and the area occupied by the circuit; in addition, it can also make the first end A of the inductor L The highest voltage is Vin/2. Compared with the two-level step-down circuit, the three-level step-down circuit helps to reduce the current ripple of the inductor L, thereby improving efficiency.

However, due to the parasitic capacitance in the step-down circuit, the MOS tube Q1-MOS tube Q4 constitutes a large power tube and the turn-on time of each MOS tube fluctuates. In the case of no external circuit, the first capacitor C1 in the step-down circuit The voltage Vc of the first capacitor C1 cannot always be kept constant (that is, the charging start voltage is equal to the discharge end voltage, for example, equal to Vin/2), so a voltage equalizing loop 41 is needed to ensure that the voltage across the first capacitor C1 can always be kept constant and equal to Vin/2. 2. The voltage equalizing loop 41 detects the voltage V1 and the voltage V2 at both ends of the first capacitor C1 to obtain the voltage Vc of the first capacitor C1, and adjusts the duty cycle of the MOS transistor Q1-MOS transistor Q4 based on the voltage Vc to achieve regulation The purpose of Vc, specifically, when the voltage Vc is higher than Vin/2, increase the discharge time of the first capacitor C1 (that is, increase the time when the control signal Ctrl1 is low and the control signal Ctrl2 is high), when When the voltage Vc is lower than Vin/2, increase the charging time of the first capacitor C1 (that is, increase the time during which the control signal Ctrl1 is at a high level and the control signal Ctrl2 is at a low level).

Taking the three-level step-down circuit in Figure 4 as one phase, the output ends of the three-level step-down circuits of each phase are connected in parallel, coupled to the same output capacitor Cout, and the output ends of the three-level step-down circuits of each phase and The voltage equalizing loop 41 is coupled to the current equalizing loop 61, and the voltage conversion circuit shown in FIG. 6 can be obtained. For each phase of the three-level step-down circuit, its working waveform can be described with reference to FIG. 5 . The current sharing loop 61 is used to ensure that the load capacity of the three-level step-down circuits of each phase is basically the same. However, the hardware circuit of the current sharing loop 61 is more complicated to realize. In the actual wiring process, each phase three-level step-down circuit is usually located in one chip, and the voltage conversion circuit needs the output terminals of multiple chips to be connected in parallel. Therefore, It is necessary to consider how to avoid interference when the current sharing signal between each chip is transmitted on the printed circuit board (PCB), and the different common modulus caused by different chips, which greatly improves the implementation complexity.

For this reason, the embodiment of the present application provides a voltage conversion circuit, which can be used as the voltage conversion circuit 1211 in the electronic device described in FIG. 1. The voltage conversion circuit includes a multi-phase three-level step-down circuit. The level step-down circuit is coupled to the next-phase three-level step-down circuit through a flying capacitor. When the flying capacitor is charged, the flying capacitor is charged by the first inductor in the next-phase three-level step-down circuit. , when the flying capacitor is discharged, the flying capacitor is discharged through the first inductor in the previous phase three-level step-down circuit. Since the voltage of the flying capacitor is kept within a certain range (ideally, it is kept constant, that is, the charge starts The voltage is equal to the discharge end voltage), so that the charging charge of the flying capacitor is equal to the discharging charge, so the average discharge current of the flying capacitor is equal to the average charging current. The flying capacitor is charged by the first inductor in the previous phase three-level step-down circuit and discharged by the first inductor in the latter phase three-level step-down circuit, so that the capacitor in the latter phase three-level step-down circuit The excitation current of the first inductor (i.e. the output current of the previous phase three-level step-down circuit) is equal to the excitation current of the first inductor in the previous phase three-level step-down circuit (i.e. the output current of the latter phase three-level step-down circuit current). Therefore, the output current of each phase of the multi-phase three-level step-down circuit of the multi-phase three-level step-down circuit is guaranteed to be the same (ie, current sharing) without an additional current sharing loop, which reduces the complexity of implementation.

In the embodiments of the present application, the flying capacitors refer to capacitors that function as energy storage in the three-level step-down circuits of each phase.

As shown in Figure 7A and Figure 7B, the voltage conversion circuit includes N phase (pieces) three-level step-down circuits (such as S1-S3), N control circuits (such as T1-T3) and output capacitor Cout, N is greater than Integer of 1. The output terminal of each phase of the three-level step-down circuit is coupled in parallel to the first terminal of the output capacitor Cout, the second terminal of the output capacitor Cout is grounded, and the two ends of the capacitor Cout are used for the output voltage Vout. The voltage conversion circuit may be set in the charging chip 121 in FIG. 1 , or there may not be one charging chip 121 in FIG. 1 , and each phase three-level step-down circuit may be set in one of the charging chips 121 .

The n-th phase three-level step-down circuit Sn includes a first capacitor Cn, a first inductor Ln, and a first switch tube Qn1, a second switch tube Qn2, a third switch tube Qn3, and a fourth switch tube Qn4 that are sequentially connected in series. The switch tube Qn1 is used for inputting the power supply voltage Vin, and the fourth switch tube Qn4 is grounded, and the above switch tube can be a MOS tube. 1≤n≤N, and n is an integer. For example, in the embodiment of the present application, N=3 is taken as an example, so the value of n may be 1, 2, or 3, but it is not intended to be limited thereto.

The first terminal of the first inductance Ln is coupled between the second switching tube Qn2 and the third switching tube Qn3, and the second terminal of the first inductance Ln is coupled to the output terminal of the voltage conversion circuit, that is, coupled to the first terminal of the output capacitor Cout one end.

As shown in FIG. 7A, the switch tube can be an N-type MOS (NMOS) tube. For the nth phase three-level step-down circuit, the drain of the first switch tube Qn1 is used to input the power supply voltage Vin, and the first switch tube The source of Qn1 and the drain of the second switch Qn2 are coupled to the first end of the first capacitor Cn, and the source of the second switch Qn2 and the drain of the third switch Qn3 are coupled to the first end of the first inductor Ln. terminal, the source of the third switch Qn3 is coupled to the drain of the fourth switch Qn4, and the source of the fourth switch Qn4 is grounded.

As shown in FIG. 7B, the switch tube can be a P-type MOS (PMOS) tube. For the nth phase three-level step-down circuit, the source of the first switch tube Qn1 is used to input the power supply voltage Vin, and the first switch tube The drain of Qn1 and the source of the second switching transistor Qn2 are coupled to the first end of the first capacitor Cn, and the drain of the second switching transistor Qn2 and the source of the third switching transistor Qn3 are coupled to the first end of the first inductor Ln. terminal, the drain of the third switching transistor Qn3 is coupled to the source of the fourth switching transistor Qn4, and the drain of the fourth switching transistor Qn4 is grounded.

The switching transistor in the embodiment of the present application is an N-type MOS (NMOS) transistor as an example, but it is not intended to be limited thereto.

The coupling mode between the three-level step-down circuits of each phase is as follows: in the N-phase three-level step-down circuit, the first end of the first capacitor of the previous phase three-level step-down circuit is coupled to the previous phase three-level step-down circuit Between the first switch tube and the second switch tube of the flat step-down circuit; the second end of the first capacitor of the previous phase three-level step-down circuit is coupled to the third switch tube of the next phase three-level step-down circuit and between the fourth switch tube. Wherein, the next phase three-level step-down circuit of the Nth phase three-level step-down circuit refers to the first-phase three-level step-down circuit. For example, when 1≤n<N, and n is an integer, the first end of the first capacitor Cn in the n-th phase three-level step-down circuit is coupled to the first switch in the n-th phase three-level step-down circuit Between the tube Qn1 and the second switch tube Qn2, the second end of the first capacitor Cn in the nth-phase three-level step-down circuit is coupled to the third switch Qn in the n+1-th phase three-level step-down circuit Between (n+1)3 and the fourth switching transistor Q(n+1)4. When n=N, the first terminal of the first capacitor CN in the Nth phase three-level step-down circuit is coupled to the first switch QN1 and the second switch QN2 in the Nth phase three-level step-down circuit Between, the second terminal of the first capacitor CN in the N-th phase three-level step-down circuit is coupled between the third switch tube Q13 and the fourth switch tube Q14 in the first-phase three-level step-down circuit.

In the above voltage conversion circuit provided by the embodiment of the present application, the first capacitor of the previous phase three-level step-down circuit can be coupled to the next phase three-level step-down circuit through the third switch tube of the latter phase three-level step-down circuit The first inductance of the circuit, and the first switching tube of the previous phase three-level step-down circuit is connected to the power supply voltage for charging, so that the average charging current of the first capacitor of the previous phase three-level step-down circuit is equal to the The excitation current of the first inductor of the first phase three-level step-down circuit; the first capacitor of the previous phase three-level step-down circuit can also be coupled to the previous phase through the second switch tube of the previous phase three-level step-down circuit The first inductance of the three-phase three-level step-down circuit is grounded and discharged through the fourth switching tube of the next three-level step-down circuit, so that the average discharge current of the first capacitor of the previous three-level step-down circuit is equal to Excitation current of the first inductor of the previous phase three-level step-down circuit. Since the charging charge of the previous phase three-level step-down circuit is equal to the discharge charge, the excitation current of the first inductor of the previous phase three-level step-down circuit is equal to the excitation current of the first inductor of the latter phase three-level step-down circuit current, and one end of the three-level step-down circuit of each phase is the output end of the three-level step-down circuit of the phase, so that the output current of the three-level step-down circuit of each phase is also equal, which reduces the difficulty of realizing the entire voltage conversion circuit.

The nth control circuit Tn includes two phase input terminals, two voltage input terminals and four output terminals. When 1≤n<N, the two phase input terminals are respectively used for input pulse width modulation (PWM) ) control signals Pn and P(n+1), the two voltage output terminals are respectively used to input the voltages (Vn1 and Vn2) of the first capacitor Cn of the n-th phase three-level step-down circuit Sn, and the four output terminals respectively coupled to the gates of the first switching transistor Qn1 and the second switching transistor Qn2 of the n-th phase three-level step-down circuit Sn and the third switch of the n+1-th phase three-level step-down circuit S(n+1) The gates of the tube Q(n+1)3 and the fourth switching tube Q(n+1)4, the first output terminal outputs the control signal Ctrln1 to the gate of the first switching tube Qn1, and the second output terminal outputs the control signal Ctrln1 to the gate of the first switching tube Qn1. The gate of the second switching tube Qn2 outputs the control signal Ctrln2, the third output terminal outputs the control signal Ctrl(n+1)3 to the third switching tube Q(n+1)3, and the fourth output terminal outputs the control signal Ctrl(n+1)3 to the fourth switching tube Q(n+1)4 outputs the control signal Ctrl(n+1)4. Wherein, the PWM control signals Pn and P(n+1) are used to adjust the duty cycle of the switching tube controlled by the control circuit Tn (ie the ratio of the switching tube being turned on and off).

When n=N, the two phase input terminals of the Nth control circuit TN are respectively used for inputting PWM control signals PN and P1, and the two voltage output terminals are respectively used for inputting the first phase of the Nth phase three-level step-down circuit SN The voltage at both ends of a capacitor Cn (VN1 and VN2), the four output terminals are respectively coupled to the gates of the first switching transistor Qn1 and the second switching transistor Qn2 of the N-phase three-level step-down circuit SN and the gates of the first phase three-level step-down circuit SN. For the gates of the third switching tube Q13 and the fourth switching tube Q14 of the level step-down circuit S1, the first output terminal outputs the control signal CtrlN1 to the gate of the first switching tube Qn1, and the second output terminal outputs the control signal CtrlN1 to the second switching tube Qn1. The gate of the transistor Qn2 outputs the control signal CtrlN2, the third output terminal outputs the control signal Ctrl13 to the third switching transistor Q13, and the fourth output terminal outputs the control signal Ctrl14 to the fourth switching transistor Q14. Wherein, the PWM control signals PN and P1 are used to adjust the duty cycle of the switching tube controlled by the control circuit TN (ie the ratio of the switching tube being turned on and off).

Each control circuit Tn can perform the following control method: control the first switch tube and the second switch tube of the previous phase three-level step-down circuit and the third switch tube and the fourth switch tube of the next phase three-level step-down circuit The tube is switched between a first state, a second state or a third state. And, the ratio of the first state or the second state is adjusted according to the voltage of the first capacitor of the previous phase three-level step-down circuit, so that the voltage of the first capacitor of the previous phase three-level step-down circuit remains within a certain range , so that the charging charge of the first capacitor of the previous phase three-level step-down circuit is equal to the discharge charge, then the average charging current of the first capacitor of the previous phase three-level step-down circuit is equal to the average discharge current.

Wherein, in the first state, the control circuit Tn controls the first switch tube of the previous phase three-level step-down circuit and the third switch tube of the next phase three-level step-down circuit to conduct, and controls the previous phase three-level step-down circuit The second switch tube of the step-down circuit and the fourth switch tube of the next phase three-level step-down circuit are turned off, so that the first capacitor of the previous phase three-level step-down circuit is coupled to the next phase three-level step-down circuit The first inductance of the circuit, and charge the first capacitor of the previous phase three-level step-down circuit, at this time, the average charging current of the first capacitor of the previous phase three-level step-down circuit is equal to the next phase three-level voltage The excitation current of the first inductor of the flat step-down circuit.

In the second state, the control circuit Tn controls the first switch tube of the previous phase three-level step-down circuit and the third switch tube of the next phase three-level step-down circuit to turn off, and controls the previous phase three-level step-down circuit The second switch tube of the voltage drop circuit and the fourth switch tube of the next phase three-level step-down circuit are turned on, so that the first capacitor of the previous phase three-level step-down circuit is coupled to the previous phase three-level step-down circuit and discharge the first capacitor, at this time, the average discharge current of the first capacitor of the previous phase three-level step-down circuit is equal to the excitation current of the first inductor of the previous phase three-level step-down circuit .

In the third state, the control circuit Tn controls the third switch tube and the fourth switch tube of the next phase three-level step-down circuit to be turned on, and controls the first switch tube and the second switch tube of the previous phase three-level step-down circuit. The switch tube is turned off, so that the first inductor of the next-phase three-level step-down circuit is grounded for demagnetization.

The control circuit Tn controls each switch tube to repeat periodically in the first state, the third state, the second state, and the third state. After the first inductor is excited in the first state or the second state every time, it must go through the third state. demagnetization.

In the embodiment of the present application, the ratio of the first state refers to the time of the first state/(the time of the first state+the time of the second state+the time of the third state). The ratio of the second state refers to the time of the second state/(the time of the first state+the time of the second state+the time of the third state). The duty cycle of the switch tube refers to the ratio of the switch tube being turned on and off.

It should be noted that in each phase of the three-level step-down circuit, more devices (such as other switch tubes) can be coupled between the first switch tube, the second switch tube, the third switch tube, and the fourth switch tube, so The first switch tube, the second switch tube, the third switch tube and the fourth switch tube are not limited to four switch tubes coupled continuously, or in other words, the first switch tube, the second switch tube, the third switch tube and the fourth switch tube The four switch tubes are not limited to four switch tubes that are continuously coupled among multiple (more than four) coupled switch tubes, as long as the first switch tube, the second switch tube, the third switch tube and the fourth switch tube and These devices can realize the coupling relationship between the first capacitance of the previous three-level step-down circuit and the first inductance of the previous three-level step-down circuit or the first inductance of the next three-level step-down circuit That's it.

Wherein, the control circuit Tn adjusts the ratio of the first state or the second state according to the voltage of the first capacitor of the previous phase three-level step-down circuit, so that the voltage of the first capacitor of the previous phase three-level step-down circuit remains at The method within a certain range is as follows: if the voltage of the first capacitor of the previous phase three-level step-down circuit is greater than the first target value, then reduce the ratio of the first state (that is, reduce the charging time of the first capacitor) or increase Increase the ratio of the second state (that is, increase the discharge time of the first capacitor), when the voltage of the first capacitor is less than the second target value, increase the ratio of the first state (that is, increase the charging time of the first capacitor) or Reduce the proportion of the second state (ie reduce the discharge time of the first capacitor). Wherein, the first target value is greater than or equal to the second target value, for example, both may be half of the input voltage Vin.

Since the first capacitor of the previous phase three-level step-down circuit is charged by the first inductor of the next phase three-level step-down circuit and discharged by the first inductor of the previous phase three-level step-down circuit, and the previous phase The average charging current of the first capacitor of the three-level step-down circuit is equal to the average discharge current, so the excitation current of the first inductor of the previous three-level step-down circuit (the output current of the previous three-level step-down circuit) is equal to The exciting current of the first inductor of the latter three-level step-down circuit (the output current of the latter three-level step-down circuit). In this way, the output current of each phase of the multi-phase three-level step-down circuit of the multi-phase three-level step-down circuit is the same (that is, the current is equalized), and the implementation difficulty of the entire voltage conversion circuit is reduced.

Specifically, when 1≤n<N, in the first state, the control circuit Tn controls the first switching tube Qn1 and the third switching tube Q(n+1)3 to be turned on, and controls the second switching tube Qn2 and the fourth switching tube Qn2 to turn on. The switch tube Q(n+1)4) is turned off, so as to couple the first capacitor Cn in the n-th phase three-level step-down circuit Sn to the n+1-th phase three-level step-down circuit S(n+1) The first inductor L(n+1) in the first capacitor Cn is charged, and the charging current of the first capacitor Cn flows through the first inductor L(n+1). In the second state, the control circuit Tn controls the first switching tube Qn1 and the third switching tube Q(n+1)3 to turn off, controls the second switching tube Qn2 and the fourth switching tube Q(n+1)4 to turn on , so as to couple the first capacitor Cn to the first inductor Ln and discharge the first capacitor Cn, and the discharge current of the first capacitor Cn flows through the first inductor Ln. In the third state, the control circuit Tn controls the third switching tube Q(n+1)3 and the fourth switching tube Q(n+1)4 to turn on, and controls the first switching tube Qn1 and the second switching tube Qn2 to turn off , making the first inductor L(n+1) grounded for demagnetization. The control circuit Tn can also adjust the ratio between the first state and the second state according to the voltage of the first capacitor Cn, so that the voltage of the first capacitor Cn remains within a certain range, that is, the average charging current of the first capacitor Cn is equal to the average discharging current.

When n=N, in the first state, the control circuit TN controls the first switching tube Qn1 and the third switching tube Q13 to turn on, and controls the second switching tube Qn2 and the fourth switching tube Q14 to turn off, so as to switch the nth phase The first capacitor Cn in the three-level step-down circuit SN is coupled to the first inductor L1 in the n+1th phase three-level step-down circuit S1, and charges the first capacitor Cn, and the charging current of the first capacitor Cn flows through the first inductor L1. In the second state, the control circuit TN controls the first switching tube Qn1 and the third switching tube Q13 to turn off, controls the second switching tube Qn2 and the fourth switching tube Q14 to turn on, so as to couple the first capacitor Cn to the first inductor Ln, and discharge the first capacitor Cn, and the discharge current of the first capacitor Cn flows through the first inductor Ln. In the third state, the control circuit TN controls the third switch Q13 and the fourth switch Q14 to turn on, and controls the first switch Qn1 and the second switch Qn2 to turn off, so that the first inductor L1 is grounded for demagnetization. The control circuit TN can also adjust the ratio between the first state and the second state according to the voltage of the first capacitor Cn, so that the voltage of the first capacitor Cn remains within a certain range, that is, the average charging current of the first capacitor Cn is equal to the average discharging current.

The level of the control signals of the same type output by the control circuits of the three-level step-down circuits of each phase is the same, but there is a sequence in time to reduce the output voltage ripple, and each control circuit is independently controlled. Exemplarily, the control circuit T1 first outputs the control signal Ctrl11, then the control circuit T2 outputs the control signal Ctrl21, and then the control circuit T3 outputs the control signal Ctrl31; the levels of the control signal Ctrl11, the control signal Ctrl21 and the control signal Ctrl31 are the same (for example, all are high or low). Similarly, the control circuit T1 first outputs the control signal Ctrl12, then the control circuit T2 outputs the control signal Ctrl22, and then the control circuit T3 outputs the control signal Ctrl32; level or low level). The control circuit T1 first outputs the control signal Ctrl123, then the control circuit T2 outputs the control signal Ctrl33, and then the control circuit T3 outputs the control signal Ctrl13; low level). The control circuit T1 first outputs the control signal Ctrl124, then the control circuit T2 outputs the control signal Ctrl34, and then the control circuit T3 outputs the control signal Ctrl14; low level).

The principle of realizing current sharing of each phase by the voltage conversion circuit will be described below with reference to FIGS. 8-19 .

For the first inductance L1 of the first-phase three-level voltage conversion circuit S1:

As shown in FIG. 8, in the first period of time, the control signal Ctrl13 output by the control circuit T3 is at a high level, making the third switching tube Q13 conduction, and the control signal Ctrl14 output by the control circuit T3 is at a low level, making the fourth The switch tube Q14 is turned off; the control signal Ctrl31 output by the control circuit T3 is at a high level, making the first switch tube Q31 turn on, and the control signal Ctrl32 output by the control circuit T3 is at a low level, making the second switch tube Q32 turn off. At this time, the first capacitor C3 is charged by the first inductor L1, so that the first inductor L1 is excited, and the excitation current of the first inductor L1 is equal to the average charging current of the first capacitor C3, and the current path is shown by the thick solid line in the figure.

As shown in FIG. 9, in the second time period, the control signal Ctrl31 and the control signal Ctrl32 output by the control circuit T3 are both low level, so that the first switching tube Q31 and the second switching tube Q32 are turned off, and the output of the control circuit T3 Both the control signal Ctrl13 and the control signal Ctrl14 are at a high level, so that the third switch Q13 and the fourth switch Q14 are turned on, and the first inductor L1 is grounded for demagnetization. The current path is shown by the thick solid line in the figure.

As shown in FIG. 10, in the third time period, the control signal Ctrl12 output by the control circuit T1 is at a high level, so that the second switch tube Q12 is turned on, and the control signal Ctrl11 output by the control circuit T1 is at a low level, so that the first The switch tube Q11 is turned off; the control signal Ctrl24 output by the control circuit T1 is at a high level, making the fourth switch tube Q24 turn on; the control signal Ctrl23 output by the control circuit T1 is at a low level, making the third switch tube Q23 off. At this time, the first capacitor C1 is discharged through the first inductor L1, so that the first inductor L1 is excited, and the excitation current of the first inductor L1 is equal to the average discharge current of the first capacitor C1, and the current path is shown by the thick solid line in the figure.

The voltage or current waveforms related to Figure 8-Figure 10 are shown in Figure 11, which shows the control signal Ctrl31/Ctrl13, control signal Ctrl12/Ctrl24, the voltage at the first end A1 of the first inductor L1, the first inductor The current of L1 and the waveform of the voltage Vc1 of the first capacitor C1.

For the first inductance L2 of the second-phase three-level voltage conversion circuit S2:

As shown in FIG. 12, in the fourth time period, the control signal Ctrl23 output by the control circuit T1 is at a high level, so that the third switch tube Q23 is turned on, and the control signal Ctrl24 output by the control circuit T1 is at a low level, so that the fourth The switch tube Q24 is turned off; the control signal Ctrl11 output by the control circuit T1 is at a high level, making the first switch tube Q11 turn on, and the control signal Ctrl12 output by the control circuit T1 is at a low level, making the second switch tube Q12 off. At this time, the first capacitor C1 is charged by the first inductor L2, so that the first inductor L2 is excited, and the excitation current of the first inductor L2 is equal to the average charging current of the first capacitor C1, and the current path is shown by the thick solid line in the figure.

As shown in FIG. 13, in the fifth time period, the control signal Ctrl11 and the control signal Ctrl12 output by the control circuit T1 are both low level, so that the first switching tube Q11 and the second switching tube Q12 are turned off, and the output of the control circuit T1 Both the control signal Ctrl23 and the control signal Ctrl124 are at a high level, so that the third switch Q23 and the fourth switch Q24 are turned on, and the first inductor L2 is grounded for demagnetization. The current path is shown by the thick solid line in the figure.

As shown in FIG. 14, in the sixth time period, the control signal Ctrl22 output by the control circuit T2 is at a high level, so that the second switch tube Q22 is turned on, and the control signal Ctrl21 output by the control circuit T2 is at a low level, so that the first The switch tube Q21 is turned off; the control signal Ctrl34 output by the control circuit T2 is at a high level, making the fourth switch tube Q34 turn on, and the control signal Ctrl33 output by the control circuit T2 is at a low level, making the third switch tube Q33 turn off. At this time, the first capacitor C2 is discharged through the first inductor L2, so that the first inductor L2 is excited, and the excitation current of the first inductor L2 is equal to the average discharge current of the first capacitor C2, and the current path is shown by the thick solid line in the figure.

The voltage or current waveforms related to Figure 12-Figure 14 are shown in Figure 15, which shows the control signal Ctrl11/Ctrl23, control signal Ctrl22/Ctrl34, the voltage at the first end A2 of the first inductor L2, the first inductor The current of L2 and the waveform of the voltage Vc2 of the first capacitor C2.

For the first inductance L3 of the third-phase three-level voltage conversion circuit S3:

As shown in Figure 16, in the seventh time period, the control signal Ctrl33 output by the control circuit T2 is at a high level, making the third switching transistor Q33 conduction, and the control signal Ctrl34 output by the control circuit T2 is at a low level, making the fourth The switch tube Q34 is turned off; the control signal Ctrl21 output by the control circuit T2 is at a high level, making the first switch tube Q21 turn on, and the control signal Ctrl22 output by the control circuit T2 is at a low level, making the second switch tube Q22 turn off. At this time, the first capacitor C2 is charged by the first inductor L3, so that the first inductor L3 is excited, and the excitation current of the first inductor L3 is equal to the average charging current of the first capacitor C2, and the current path is shown by the thick solid line in the figure.

As shown in FIG. 17, in the eighth time period, the control signal Ctrl21 and the control signal Ctrl22 output by the control circuit T2 are both at low level, so that the first switching tube Q21 and the second switching tube Q22 are turned off, and the output of the control circuit T2 Both the control signal Ctrl33 and the control signal Ctrl34 are high level, so that the third switch Q33 and the fourth switch Q34 are turned on, and the first inductor L3 is grounded for demagnetization. The current path is shown by the thick solid line in the figure.

As shown in FIG. 18, in the ninth time period, the control signal Ctrl32 output by the control circuit T3 is at a high level, so that the second switch tube Q32 is turned on, and the control signal Ctrl31 output by the control circuit T3 is at a low level, so that the first The switch tube Q31 is turned off; the control signal Ctrl14 output by the control circuit T3 is at a high level, making the fourth switch tube Q14 turn on; the control signal Ctrl13 output by the control circuit T3 is at a low level, so that the third switch tube Q13 is turned off. At this time, the first capacitor C3 is discharged through the first inductor L3, so that the first inductor L3 is excited, and the excitation current of the first inductor L3 is equal to the average discharge current of the first capacitor C3, and the current path is shown by the thick solid line in the figure.

The voltage or current waveforms related to Figure 16-Figure 18 are shown in Figure 19, which shows the control signal Ctrl21/Ctrl33, control signal Ctrl32/Ctrl14, the voltage at the first end A3 of the first inductance L3, the first inductance The current of L3 and the waveform of the voltage Vc3 of the first capacitor C3.

For each control circuit to adjust the ratio of the first state or the second state according to the voltage of the first capacitor:

The control circuit T1 detects the voltage of the first capacitor C1, and adjusts the third time period (the first capacitor C1 is discharged in the second state) and the fourth time period (the first capacitor C1 is charged in the first state) according to the voltage of the first capacitor C1. ) and the ratio of the fifth time period (the demagnetization of the first inductor L2 in the third state), so as to maintain the voltage of the first capacitor C1 within a certain range (for example, a constant value Vin/2), so that the voltage of the first capacitor C1 The charge charge is equal to the discharge charge, so the average discharge current of the first capacitor C1 is equal to the average charge current. For example, when the voltage of the first capacitor C1 is greater than Vin/2, increase the proportion of the third time period or decrease the proportion of the fourth time period; when the voltage of the first capacitor C1 is less than Vin/2, decrease The proportion of the third time period or increase the proportion of the fourth time period.

Furthermore, in the third time period of FIG. 10, the excitation current of the first inductor L1 is equal to the average discharge current of the first capacitor C1, and, in the fourth time period of FIG. 12, the excitation current of the first inductor L2 is equal to that of the first capacitor C1. The average charging current, so the excitation current of the first inductor L1 is equal to the excitation current of the first inductor L2, that is, the average currents of the first inductor L1 and the first inductor L2 in the charging and discharging states of the first capacitor C1 are equal.

Similarly, the control circuit T2 detects the voltage of the first capacitor C2, and adjusts the sixth time period (the first capacitor C2 is discharged in the second state) and the seventh time period (the first capacitor C2 is discharged in the first state) according to the voltage of the first capacitor C2. Capacitor C2 charging) and the ratio of the eighth time period (the demagnetization of the first inductor L3 in the third state), so as to maintain the voltage of the first capacitor C2 within a certain range (for example, a constant value Vin/2), so that the first The charging charge of the capacitor C2 is equal to the discharging charge, so the average discharging current of the first capacitor C2 is equal to the average charging current. For example, when the voltage of the first capacitor C2 is greater than Vin/2, increase the proportion of the sixth time period or decrease the proportion of the seventh time period; when the voltage of the first capacitor C2 is less than Vin/2, decrease The proportion of the sixth time period or increase the proportion of the seventh time period.

Combined with the excitation current of the first inductor L2 in the sixth time period of Figure 14 is equal to the average discharge current of the first capacitor C2, and the excitation current of the first inductor L3 in the seventh time period of Figure 16 is equal to that of the first capacitor C2 The average charging current, so the excitation current of the first inductor L2 is equal to the excitation current of the first inductor L3, that is, the excitation currents of the first inductor L2 and the first inductor L3 are the same when the first capacitor C2 is charging and discharging.

Similarly, the control circuit T3 detects the voltage of the first capacitor C3, and adjusts the ninth time period (discharge of the first capacitor C3 in the second state), the first time period (the first time period in the first state) according to the voltage of the first capacitor C3. Capacitor C3 charging) and the ratio of the second time period (first inductor L1 demagnetization in the third state), so as to maintain the voltage of the first capacitor C3 within a certain range (for example, a constant value Vin/2), so that the first The charging charge of the capacitor C3 is equal to the discharging charge, so the average discharging current of the first capacitor C3 is equal to the average charging current. For example, when the voltage of the first capacitor C3 is greater than Vin/2, increase the proportion of the ninth time period or decrease the proportion of the first time period; when the voltage of the first capacitor C3 is less than Vin/2, decrease The proportion of the ninth time period or increase the proportion of the first time period.

Combined with the ninth time period in FIG. 18, the excitation current of the first inductor L3 is equal to the average discharge current of the first capacitor C3, and the excitation current of the first inductor L1 in the first time period of FIG. 8 is equal to that of the first capacitor C3. The average charging current, so the excitation current of the first inductor L3 is equal to the excitation current of the first inductor L1, that is, the excitation currents of the first inductor L3 and the first inductor L1 are the same when the first capacitor C3 is charging and discharging.

By analogy, for the voltage conversion circuit including the N-phase three-level step-down circuit provided in the embodiment of the present application, it can be obtained that the excitation current of the inductance of each phase three-level step-down circuit is the same, that is, each phase is three-level The average current output by the step-down circuit is the same, so as to realize the current sharing of the output of the voltage conversion circuit. Compared with the voltage conversion circuit in Fig. 6, no additional current sharing loop is needed, which reduces the complexity of implementation.

The embodiment of the present application also provides a computer-readable storage medium, where instructions are stored in the computer-readable storage medium, and the instructions are executed on the electronic device, so that the electronic device executes the above control method.

The embodiment of the present application also provides a computer program product including instructions, the instructions run on the electronic device, so that the electronic device executes the above control method.

Those skilled in the art can appreciate that the modules and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed by hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but such implementation should not be regarded as exceeding the scope of the present application.

The modules described as separate components may or may not be physically separated, and the components displayed as modules may or may not be physical modules, that is, they may be located in one device, or may be distributed to multiple devices. Part or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional module in each embodiment of the present application may be integrated into one device, or each module may physically exist separately, or two or more modules may be integrated into one device.

The above is only a specific implementation of the application, but the scope of protection of the application is not limited thereto. Anyone familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the application. Should be covered within the protection scope of this application. Therefore, the protection scope of the present application should be determined by the protection scope of the claims.

Claims (7)

A voltage conversion circuit, characterized in that it includes an N-phase three-level step-down circuit, and each phase of the three-level step-down circuit in the N-phase three-level step-down circuit includes a first inductor, a first capacitor, and sequentially A first switching tube, a second switching tube, a third switching tube and a fourth switching tube connected in series; the first switching tube inputs a power supply voltage, and the fourth switching tube is grounded; the first end of the first inductor is coupled Between the second switch tube and the third switch tube, the second end of the first inductor is coupled to the output end of the voltage conversion circuit; In the N-phase three-level step-down circuit, the first terminal of the first capacitor of the previous phase three-level step-down circuit is coupled to the first switch tube and the first switch tube of the previous phase three-level step-down circuit Between the two switch tubes; the second end of the first capacitor of the previous phase three-level step-down circuit is coupled to between the third switch tube and the fourth switch tube of the next phase three-level step-down circuit; Wherein, the last phase three-level step-down circuit of the Nth phase three-level step-down circuit in the N-phase three-level step-down circuit refers to the first phase three-level step-down circuit in the N-phase three-level step-down circuit. In the level step-down circuit, N is an integer greater than 1. The voltage conversion circuit according to claim 1, further comprising a control circuit, the control circuit is used to control the first switching tube, the second switching tube and the The third switching tube and the fourth switching tube of the next-phase three-level step-down circuit are switched between the first state, the second state or the third state; Wherein, the first state makes the first capacitance of the previous phase three-level step-down circuit coupled to the first inductance of the next-phase three-level step-down circuit, and the first phase three-level step-down circuit charging the first capacitor of the flat step-down circuit; the second state makes the first capacitor of the previous phase three-level step-down circuit coupled to the first inductance of the previous phase three-level step-down circuit, and discharge the first capacitor; the third state demagnetizes the first inductor of the next-phase three-level step-down circuit to ground. The voltage conversion circuit according to claim 2, wherein, in the first state, the control circuit is used to control the first switching tube of the previous phase three-level step-down circuit and the next The third switch tube of the phase three-level step-down circuit is turned on, and the second switch tube of the previous phase three-level step-down circuit and the fourth switch tube of the next phase three-level step-down circuit are controlled to be turned off. broken. The voltage conversion circuit according to claim 2, wherein, in the second state, the control circuit is used to control the first switching tube of the previous phase three-level step-down circuit and the lower The third switch tube of the one-phase three-level step-down circuit is turned off, and the second switch tube of the previous phase three-level step-down circuit and the fourth switch tube of the next-phase three-level step-down circuit are controlled conduction. The voltage conversion circuit according to claim 2, wherein, in the third state, the control circuit is used to control the third switch tube and the fourth switch of the next-phase three-level step-down circuit The tube is turned on, and the first switch tube and the second switch tube of the previous phase three-level step-down circuit are controlled to be turned off. The voltage conversion circuit according to any one of claims 2-5, wherein the control circuit is also used for: If the voltage of the first capacitor of the previous phase three-level step-down circuit is greater than the first target value, then reduce the ratio of the first state or increase the ratio of the second state; if the previous If the voltage of the first capacitor of the three-phase three-level step-down circuit is less than the second target value, then increase the proportion of the first state or decrease the proportion of the second state, and the first target value is greater than or equal to the Describe the second target value. An electronic device, characterized in that it comprises the voltage conversion circuit according to any one of claims 1-6 and a working circuit, the voltage conversion circuit is used to supply power to the working circuit.

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