CN218868110U

CN218868110U - DC conversion circuit and charging system

Info

Publication number: CN218868110U
Application number: CN202222421355.0U
Authority: CN
Inventors: 谭泽芳
Original assignee: Anker Innovations Co Ltd
Current assignee: Anker Innovations Co Ltd
Priority date: 2022-09-13
Filing date: 2022-09-13
Publication date: 2023-04-14
Anticipated expiration: 2032-09-13

Abstract

The application discloses a direct current conversion circuit and a charging system, the direct current conversion circuit comprises a voltage conversion circuit and a power regulating circuit, wherein the voltage conversion circuit comprises a first on-off device, a second on-off device, a transformer, a capacitor and a first resistor, the first on-off device, the second on-off device and the first resistor are connected in series between an input voltage and a ground voltage, a primary winding of the transformer is connected in series with the capacitor, the primary winding and the capacitor after being connected in series are further connected in parallel with the second on-off device, and the first on-off device and the second on-off device are not conducted at the same time; the power conditioning circuit includes a second resistor that can be selectively connected in parallel or in series with the first resistor. Through the mode, the access resistance value of the direct current conversion circuit can be changed by changing the power adjusting circuit, so that the load power or the output power of the direct current conversion circuit is changed, and the possibility of the problems of free oscillation, electromagnetic interference conduction and the like caused by too low switching frequency of the first on-off device is reduced.

Description

DC conversion circuit and charging system

Technical Field

The application relates to the technical field of power electronics, in particular to a direct current conversion circuit and a charging system.

Background

The DC/DC conversion circuit is a circuit for supplying power, and outputs power mainly by using inductance and capacitance energy storage characteristics. The inductor and the capacitor can output the energy input into the DC/DC conversion circuit in the processes of storing energy and releasing energy. The frequency of energy storage and energy release of the inductor and the capacitor can be controlled through a controllable switch (such as an MOS (metal oxide semiconductor) transistor), and the power output by the DC/DC conversion circuit is further controlled.

In the operation process of the existing DC/DC conversion circuit, if the power required to be output is smaller, the DC/DC conversion circuit needs smaller load power in operation. The load power or the output power of the DC/DC conversion circuit can be reduced by reducing the frequency of energy storage and release of the inductor and the capacitor through the controllable switch. However, if the frequency of energy storage and release of the inductor and the capacitor or the switching frequency of the controllable switch is too low, problems such as free oscillation and electromagnetic interference conduction are easily caused.

Disclosure of Invention

The technical problem that this application mainly solved provides direct current converting circuit and charging system, can improve among the prior art DC/DC converting circuit when with less load power operation, produces free oscillation, conduction electromagnetic interference scheduling problem easily.

In order to solve the technical problem, the application adopts a technical scheme that: providing a direct current conversion circuit, wherein the direct current conversion circuit comprises a voltage conversion circuit and a power regulation circuit, the voltage conversion circuit comprises a first on-off device, a second on-off device, a transformer, a capacitor and a first resistor, the first on-off device, the second on-off device and the first resistor are connected in series between an input voltage and a ground voltage, a primary winding and the capacitor of the transformer are connected in series, the primary winding and the capacitor after being connected in series are further connected in parallel with the second on-off device, and the first on-off device and the second on-off device are not conducted at the same time; the power conditioning circuit includes a second resistor that can be selectively connected in parallel or in series with the first resistor.

In order to solve the above technical problem, another technical solution adopted by the present application is: a charging system is provided that includes a DC conversion circuit.

The beneficial effect of this application is: different from the situation of the related art, the connection situation of the second resistor and the first resistor of the power regulating circuit is changed to change the resistance value of the access resistor of the direct current conversion circuit. When the resistance value of the access resistor is larger, the load power of the direct current conversion circuit is smaller, and when the resistance value of the access resistor is smaller, the load power of the direct current conversion circuit is larger. Therefore, under the condition that the switching frequency of the first on-off device is not changed or is changed as little as possible, the load power or the output power of the direct current conversion circuit can be changed, and the possibility of the problems of free oscillation, conducted electromagnetic interference and the like caused by the fact that the switching frequency of the first on-off device is too low is reduced.

Drawings

FIG. 1 is a block diagram of an embodiment of a DC converter circuit of the present application;

FIG. 2 is a circuit diagram of a first embodiment of a DC converter circuit according to the present application;

FIG. 3 is a circuit diagram of a second embodiment of a DC converter circuit according to the present application;

FIG. 4 is a waveform timing diagram of a voltage converting circuit according to an embodiment of the present invention in a continuous mode;

fig. 5 is a waveform timing diagram of a voltage conversion circuit according to an embodiment of the dc-to-dc converter circuit in the present application in the discontinuous mode.

Detailed Description

The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The DC conversion circuit is a circuit for supplying power, and in other examples, the DC conversion circuit may also be referred to as a DC/DC conversion circuit, a DC conversion circuit, or the like. The direct current conversion circuit can output power by utilizing the energy storage characteristics of an inductor and a capacitor. Specifically, the inductor and the capacitor of the dc conversion circuit can output the energy input into the dc conversion circuit during the process of storing and releasing the energy. In addition, the frequency (switching frequency) of energy storage and release of the inductor and the capacitor can be controlled to further control the power output by the direct current conversion circuit. That is, the dc conversion circuit is a power supply circuit that can output different voltages or different powers.

The inventors of the present application have long studied and found that, in the related art, the switching frequency of the dc conversion circuit is relatively high for the stability of the output power in general. When a small power is required to be output, that is, the dc converter circuit is under a light load (the operating power is relatively small), if the switching frequency is kept in a relatively high state, the loss of the dc converter circuit may be large. Therefore, if small power needs to be output, the switching frequency of the direct current conversion circuit can be reduced, so that the frequency of energy storage and energy release of the inductor and the capacitor is reduced, and the power output by the direct current conversion circuit can be reduced. Although the above means can reduce the loss of the dc conversion circuit to some extent, it may increase the possibility that the dc circuit generates free oscillation and conducts electromagnetic interference. In order to solve the above technical problems, the present application proposes the following embodiments.

The following exemplary embodiments of the dc conversion circuit of the present application describe a dc conversion circuit.

Referring to fig. 1, in some examples, the dc conversion circuit 100 may include a voltage conversion circuit 110. The voltage converting circuit 110 is coupled to an input power source and can output power.

Referring to fig. 2 or 3, in some examples, the voltage conversion circuit 110 may be an asymmetric half-bridge-zero voltage switching (AHB-ZVS) based conversion circuit. Specifically, the voltage conversion circuit 110 may include a first switch Q1, a second switch Q2, a transformer T, a capacitor C, and a first resistor R1. Among them, the first and second switches Q1 and Q2 and the first resistor R1 may be connected in series between the input voltage V0 and a ground voltage (input power). The transformer T may have a primary winding and a secondary winding. The primary winding may be connected in series with a capacitor C, and the series connected primary winding and capacitor C are further connected in parallel with a second switch Q2. The first and second switches Q1 and Q2 are not turned on at the same time.

Fig. 4 and 5 are waveform timing diagrams respectively showing the voltage conversion circuit of the embodiment of the dc conversion circuit of the present application in the continuous mode and the discontinuous mode. Wherein, U _Q1 The control signal of the first on/off switch Q1 may be used to control the on/off of the first on/off switch Q1. U shape _Q2 Is a control signal of the second switch Q2 for controlling the on/off of the second switch Q2. U shape _C Is the voltage across the capacitor C. In some examples, the first switch Q1 may be at U _Q1 Is turned on at high level and is in U _Q1 And is turned off when low. The second switch Q2 may be at U _Q2 Is turned on at a high level at U _Q2 And is turned off when low.

Referring to FIGS. 4 and 5, at P ₁ In a phase when the first switch Q1 is turned on and the second switch Q2 is turned off, the primary winding may be connected in series with the capacitor C and interposed between the input voltage V0 and the ground voltage. In this case, the input voltage may charge the capacitor C, i.e. the capacitor C and the primary winding may store energy. At P ₂ In phase, when the first switch Q1 is turned off and the second switch Q2 is turned on, the capacitor C is coupled across the primary winding. In this case, the capacitor C is discharged, thereby releasing the stored energy. That is, when the first switch Q1 is turned on, the input voltage and the ground voltage are simultaneously applied to both ends of the primary winding and the capacitor C connected in series and charge the capacitor C, and when the second switch Q2 is turned on, the capacitor C is applied to both ends of the primary winding. By repeating the above steps, the voltage conversion circuit 110 can convert the energy of the input power into the output.

Comparing fig. 4 and 5, the duty ratio of the first on-off Q1 is controlled to be decreased, that is, the ratio (P) of the sum of the time the first on-off Q1 is turned on and the time the first on-off Q1 and the second on-off Q2 are turned on ₁ ：P ₁ +P ₂ ) The time that the input voltage can be charged to the capacitor C is reduced, and the time that the capacitor C is discharged to the primary coil is increased, thereby enabling the output power of the voltage conversion circuit 110 to be reduced.

As the duty ratio of the first switch Q1 is gradually decreased, the voltage conversion circuit 110 may enter the discontinuous mode from the continuous mode. Here, the discontinuous mode means that P is caused by a small duty ratio of the first on-off device Q1 (or a large duty ratio of the second on-off device Q2) during charging ₂ The period of time during which the capacitor C is discharged is shorter than the turn-on period of the second switch Q2. In this case, problems such as free oscillation, electromagnetic conduction interference, and the like are easily generated. Correspondingly, the continuous mode means P ₂ The period of time that the capacitor C is discharged in the stage is not less than the on period of time of the second switch Q2.

Referring to fig. 2 and 3, the dc conversion circuit 100 may further include a power conditioning circuit 120. The power adjusting circuit 120 is coupled to the voltage converting circuit 110, and is used for controlling the output power and/or the output voltage of the voltage converting circuit 110. The power conditioning circuit includes a second resistor R2 that can be selectively connected in parallel or in series with the first resistor R1.

Different from the related art, the connection condition of the second resistor R2 and the first resistor R1 of the power conditioning circuit 120 is changed to change the resistance value of the access resistor of the dc-to-dc conversion circuit 100. Since the input voltage V0 is constant, the current in the dc conversion circuit 100 decreases when the resistance value of the access resistor increases. Therefore, the output power of the dc conversion circuit 100 is reduced and the load power is reduced. When the resistance value of the access resistor is reduced, the circuit in the dc conversion circuit 100 is increased, the output power of the dc conversion circuit 100 is increased, and the load power is increased. Accordingly, the load power or the output power of the dc conversion circuit 100 can be changed without changing the switching frequency of the first switch Q1 as much as possible or with changing the switching frequency of the first switch Q1 as little as possible, thereby reducing the possibility of the occurrence of problems such as free oscillation and electromagnetic interference due to the low switching frequency of the first switch Q1. In other words, the load power or the output power of the dc conversion circuit 100 can be changed without changing the duty ratio of the first switch Q1 as much as possible or with changing the duty ratio as little as possible, thereby reducing the possibility that the dc conversion circuit 100 enters the discontinuous mode.

Referring to fig. 2, in some examples, the power regulating circuit 120 may include a third switch Q3 and a second resistor R2. The third switch Q3 is connected in series with the second resistor R2, and the series-connected third switch Q3 and second resistor R2 may be further connected in parallel with the first resistor R1.

In this case, when the third interrupter Q3 is turned on, the first resistor R1 and the second resistor R2 are connected in parallel. The resistance value of the access resistor of the dc conversion circuit 100 decreases and the output power increases. When the third switch is turned off, the connection resistance of the dc conversion circuit 100 increases, and the output power decreases.

Referring to fig. 3, in other examples, the second resistor R2 of the power conditioning circuit 120 may be in series with the first resistor R1. The third interrupter Q3 is connected in parallel to the second resistor R2.

In this case, when the third switch Q3 is turned on, the third switch Q3 short-circuits the second resistor R2, or the third switch Q3 is connected in parallel with the second resistor R2, so that the resistance value of the access resistor is decreased, and the output power of the dc conversion circuit 100 can be increased. Similarly, when the third switch Q3 is turned off, the output power of the dc conversion circuit 100 decreases.

In summary, the power conditioning circuit 120 can control the output power of the voltage converting circuit 110 to increase or decrease to adapt to the charging requirements of different specifications of electric devices.

In some examples, the dc conversion circuit 100 may further include a first control circuit 130. The first control circuit 130 may be coupled to the power conditioning circuit 120 and output a command to the power conditioning circuit 120. The power adjusting circuit 120 may receive an instruction from the first control circuit 130 and control the output power of the dc conversion circuit based on the instruction.

In some examples, the first control circuit 130 may be an integrated circuit chip having signal processing capabilities. Additionally, the MCU may also be a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components. A general purpose processor may be a Microprocessor (MCU) or the processor may be any conventional processor or the like. Preferably, the first control circuit 130 may be a micro processing unit (MCU).

In this case, when the first control circuit 13 receives a signal requesting a high power output, the first control circuit 130 may issue an instruction to the power adjusting circuit 120 to control the third switch Q3 to be turned on, so that the output power of the dc conversion circuit 100 is increased. When the first control circuit 130 receives the signal requesting the small power output, the first control circuit 130 may send an instruction to the power regulating circuit 120 to control the third switch Q3 to be switched off, so as to reduce the output power of the dc conversion circuit 100.

Specifically, the output end of the first control circuit 130 may be connected to the control end of the third breaker Q3, and the first control circuit 130 obtains the load power or the output power of the dc conversion circuit 100, and controls the third breaker Q3 to be turned on when the load power or the output power is greater than the preset power, and controls the third breaker Q3 to be turned off when the load power or the output power is less than the preset power.

In some examples, the third fuse Q3 may be a MOS transistor. The first control circuit 130 may turn off the third interrupter Q3 in such a manner that a low level is output to the control terminal. The first control circuit 130 may turn on the third turn-off device Q3 in such a manner that a high level is output to the control terminal. In addition, the power regulation circuit 120 may further include a third resistor R3, where one end of the third resistor R3 is coupled to the gate of the MOS transistor, and the other end is coupled to the source of the MOS transistor. In this case, the third resistor R3 can play a role of preventing static electricity, and can reduce the possibility that the gate and the source of the MOSFET are damaged due to malfunction of the MOS transistor.

In some examples, the dc conversion circuit 100 may further include a second control circuit 140. A first output terminal of the second control circuit 140 is connected to a control terminal of the first switch Q1, and controls the first switch Q1 to be turned on by outputting a first signal to the first switch Q1. In addition, the duty ratio of the first switch Q1 can be controlled by the output terminal of the second control circuit 140.

In some examples, the second control circuit 140 further includes a second output. The second output terminal may be connected to a control terminal of the second switch Q2, and controls the second switch Q2 to be turned on by outputting a second signal to the second switch Q2. The first signal and the second signal are alternately input. The duty ratio of the first switch Q1 may be controlled by controlling the durations of the first and second signals.

Specifically, the first switch Q1 may be a MOS transistor. The second switch Q2 may be a MOS transistor. In other examples, the second switch Q2 may be a diode. In this case, when the first switch Q1 is turned off, the diode may be turned on to load the capacitor C across the primary winding.

In some examples, the second control circuit 140 controls the duty ratio of the first signal based on the load power or the output power of the dc conversion circuit 100. In other examples, the second control circuit 140 may control the duty cycles of the first signal and the second signal based on the load power or the output power of the dc conversion circuit 100.

In some examples, the first control circuit 130 may be electrically connected to the second control circuit 140, either directly or indirectly. In other examples, the first control circuit 130 may be communicatively coupled to a second control circuit.

In addition, the application also provides a charging system which comprises the direct current conversion circuit. Specifically, the charging system may include a voltage conversion circuit 110 and a power regulation circuit 120, wherein the voltage conversion circuit 110 includes a first switch Q1, a second switch Q2, a transformer T, a capacitor C, and a first resistor R1. The first and second switches Q1 and Q2 and the first resistor R1 are connected in series between the input voltage V0 and the ground voltage. A primary winding of the transformer T is connected with a capacitor C in series, the primary winding and the capacitor C after being connected in series are further connected with a second on-off device Q2 in parallel, and the first on-off device Q1 and the second on-off device Q2 are not conducted at the same time; the power conditioning circuit 120 includes a second resistor R2 that can be selectively connected in parallel or in series with the first resistor R1.

For the description of the dc conversion circuit 100 in the charging system, reference may be made to the above description of the dc conversion circuit embodiment of the present application, and details are not repeated herein.

In summary, the resistance value of the dc conversion circuit 100 is adjusted by the power adjusting circuit 120, so that the dc conversion circuit can be in a continuous mode in a high load state, a low load state, a high power output or a low power output scene, and the possibility that the dc conversion circuit 100 enters an intermittent mode, thereby generating free oscillation, conducting electromagnetic interference and other problems is reduced.

The above description is only an example of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings, or which are directly or indirectly applied to other related technical fields, are intended to be included within the scope of the present application.

Claims

1. A dc conversion circuit, comprising:

a voltage conversion circuit including a first switch, a second switch, a transformer, a capacitor, and a first resistor, the first switch, the second switch, and the first resistor being connected in series between an input voltage and a ground voltage, a primary winding of the transformer being connected in series with the capacitor, the primary winding and the capacitor being further connected in parallel with the second switch, the first switch and the second switch not being turned on at the same time;

a power conditioning circuit comprising a second resistor selectively connectable in parallel or in series with the first resistor.

2. The dc conversion circuit according to claim 1, wherein:

the power regulating circuit further comprises a third switch connected in series with the second resistor, and the series-connected third switch and the second resistor are further connected in parallel with the first resistor.

3. The dc conversion circuit according to claim 1, wherein:

the power regulating circuit further includes a third switch, the second resistance being in series with the first resistance, the third switch being in parallel with the second resistance.

4. The direct current conversion circuit according to claim 2 or 3, characterized in that:

the direct current conversion circuit further comprises a first control circuit, an output end of the first control circuit is connected with a control end of the third breaker, the first control circuit obtains load power of the direct current conversion circuit, controls the third breaker to be switched on when the load power is larger than preset power, and controls the third breaker to be switched off when the load power is smaller than the preset power.

5. The dc conversion circuit according to claim 4, wherein:

the third interrupter is an MOS transistor, and the power regulating circuit further includes a third resistor, one end of the third resistor is coupled to the gate of the MOS transistor, and the other end of the third resistor is coupled to the source of the MOS transistor.

6. The dc conversion circuit according to claim 4, wherein:

the direct current conversion circuit further comprises a second control circuit, wherein a first output end of the second control circuit is connected with a control end of the first on-off device, and the first on-off device is controlled to be switched on by outputting a first signal to the first on-off device.

7. The dc conversion circuit according to claim 6, wherein:

the second control circuit further includes a second output terminal connected to a control terminal of the second switch, and controlling the second switch to be turned on by outputting a second signal to the second switch, the first signal and the second signal being alternately input.

8. The dc conversion circuit according to claim 6, wherein:

the second control circuit controls the duty ratio of the first signal based on the load power of the direct current conversion circuit.

9. The dc conversion circuit according to claim 1, wherein:

when the first on-off device is turned on, the input voltage and the ground voltage are loaded at the two ends of the primary winding and the capacitor which are connected in series at the same time and charge the capacitor,

when the second on-off switch is switched on, the capacitor is loaded across the primary winding.

10. A charging system, characterized by:

the charging system includes the dc conversion circuit of any one of claims 1-9.