CN117996928B - Multi-port output charger and control method thereof - Google Patents

The invention provides a multi-port output charger and a control method thereof, wherein the charger comprises a rectifying module, a first DC-DC conversion module, a first protocol chip and a second switch, wherein the input end of the first DC-DC conversion module is connected in parallel with the output end of the rectifying module, the output voltage of the first DC-DC conversion module is subjected to power distribution and voltage regulation through the first protocol chip to obtain electric energy required by a first output port, the input end of the second DC-DC conversion module is connected in parallel with the output end of the rectifying module, the output voltage of the second DC-DC conversion module is subjected to power distribution and voltage regulation through the second protocol chip to obtain electric energy required by a second output port, and the output end of the first DC-DC conversion module is connected in parallel with the output end of the second DC-DC conversion module through the second switch. The invention has simple structure, solves the problem that the DC-DC conversion module is easy to concentrate heat, and has high working efficiency and high reliability.

Multi-port output charger and control method thereof

Technical Field

The invention relates to the technical field of chargers, in particular to a multi-port output charger and a control method thereof.

Background

In the existing multi-port output PD chargers, for example, 2c+1a or 3c+1a, in order to achieve that the C port outputs various voltages such as 20V, 15V, 12V, 9V, 5V, etc., and the a port outputs various voltages such as 12V, 9V, 5V, etc., it is common practice to: the front stage uses a flyback converter to obtain direct current voltage, and the rear stage adds a plurality of Buck (Buck) or Buck-Boost (Buck-Boost) converters to obtain direct current voltage required by the C port and the A port; the various output voltages of the port C and the port A are obtained by adjusting the feedback or the voltage division ratio of Buck or Buck-Boost through a PD protocol IC, and if the input power is more than 75W, a Power Factor Correction (PFC) circuit is also needed to form a three-stage series structure.

Taking a PD charger carrying 2 output ports TYPE-C (output ports TYPE-C1 and TYPE-C2) and 1 output port TYPE-a as an example, as shown in fig. 1, a multi-port output charger in the prior art includes a rectifying module 11, a first DC-DC converting module 12 and a control output module 14, an alternating current u _in is rectified by the rectifying module 11 to obtain a pulsating high voltage direct current, the first DC-DC converting module 12 is connected in parallel to an output port of the rectifying module 11, and the pulsating high voltage direct current is input to the first DC-DC converting module 12 to output a low voltage direct current voltage V _out to supply power to the control output module 14.

The rectifying module 11 comprises a diode D ₁~D₄ and a capacitor C ₁, the diode D ₁ and the diode D ₂ are connected in parallel to form a first bridge arm, the diode D ₃ and the diode D ₄ are connected in parallel to form a second bridge arm, the second bridge arm is connected in parallel to the first bridge arm, and the capacitor C ₁ is connected in parallel to the second bridge arm.

The first DC-DC conversion module 12 includes a capacitor C ₂~C₃, a resistor R ₁, a diode D ₅~D₆, a switching tube Q ₁ and a transformer T ₁, A first end of the primary winding of the transformer T ₁ is connected to a first end of the capacitor C ₁, an anode of the diode D ₅ is connected to a second end of the primary winding of the transformer T ₁, the cathode of the diode D ₅ is connected with one end of the resistor R ₁, the other end of the resistor R ₁ is connected with the first end of the primary winding of the transformer T ₁, The capacitor C ₂ is connected in parallel with two ends of the resistor R ₁, the drain electrode of the switching tube Q ₁ is connected with the anode of the diode D ₅, The source electrode of the switch tube Q ₁ is connected with the second end of the capacitor C ₁, the second end of the capacitor C ₁ is grounded, the first end of the secondary winding of the transformer T ₁ is connected with the anode of the diode D ₆, the cathode of the diode D ₆ outputs the low-voltage direct-current voltage V _out, the cathode of the diode D ₆ is connected with one end of the capacitor C ₃, The other end of the capacitor C ₃ is connected to the second end of the secondary winding of the transformer T ₁, and the second end of the secondary winding of the transformer T ₁ is connected to the ground terminal SGND.

The control output module 14 includes a first dc-dc converter 141, a first protocol chip 142, a second dc-dc converter 143, and a second protocol chip 144, where the low-voltage dc voltage V _out is input to the first dc-dc converter 141 to obtain a voltage V _{out_C1}, and an output end of the first dc-dc converter 141 is connected in parallel to a first output port P1, where the first output port P1 is, for example, TYPE-C, TYPE-a. The first protocol chip 142 is connected to the first output port. The low-voltage dc voltage V _out is input to the second dc-dc converter 143 to obtain a voltage V _{out_C2}, and an output end of the second dc-dc converter 143 is connected in parallel to a second output port P2, where the second output port P2 is, for example, TYPE-C, TYPE-a. The second protocol chip 144 is connected to the second output port P2. The first and second dc-dc converters 141 and 143 may be Buck (Buck) or Buck-Boost (Buck-Boost) converters.

The above prior art has the following disadvantages: the efficiency is low; the circuit is complex and has larger volume; the cost is high; one flyback converter bears the total output power, and heat concentration is easy to occur, so that heat dissipation is not easy. Therefore, a new circuit structure of the multi-port output PD charger is needed, which overcomes the limitations of the prior art, and solves the heat concentration problem, improves the efficiency, reduces the volume and optimizes the cost while simplifying the circuit structure; simultaneously, a new control method is correspondingly provided, and the use of the new multi-port output PD charger is perfected.

Disclosure of Invention

In order to solve the technical problems, the multi-port output charger provided by the invention adopts the following technical scheme:

A multi-port output charger comprises,

The input end of the rectifying module is connected with alternating current,

The input end of the first DC-DC conversion module is connected in parallel with the output end of the rectification module, the output end of the first DC-DC conversion module is connected in parallel with a first output port,

A first protocol chip for detecting the load connection state of the first output port and the power of the load of the first output port,

The input end of the second DC-DC conversion module is connected in parallel with the output end of the rectification module, the output end of the second DC-DC conversion module is connected in parallel with a second output port,

A second protocol chip for detecting the load connection state of the second output port and the power of the load of the second output port,

And the output end of the first DC-DC conversion module is connected with the output end of the second DC-DC conversion module in parallel through the second switch.

The first and second protocol chips detect load connection states of the first output port and the second output port, and when the first output port and the second output port are both connected with a load, the second switch is in an off state; when only one of the first output port and the second output port is connected with a load, the second protocol chip controls the second switch to be in a closed state.

The second switch is a bidirectional switch.

The first DC-DC conversion module works in a constant voltage mode, and the second DC-DC conversion module is switched between the constant voltage mode and the constant current mode.

When only one of the first output port and the second output port is connected with a load, the second switch is closed, when the second DC-DC conversion module is in a constant voltage mode, the output voltage of the second DC-DC conversion module is higher than the output voltage of the first DC-DC conversion module, and when the power of the load connected to the first or second output port is higher than the output power of the second DC-DC conversion module, the second DC-DC conversion module is switched to a constant current mode. The output voltage of the second DC-DC conversion module is equal to the voltage of the first DC-DC conversion module, and the first DC-DC conversion module and the second DC-DC conversion module supply power to a load at the same time, so that the problem that a single flyback conversion module is easy to concentrate heat is solved.

The second DC-DC conversion module comprises a power conversion unit and a constant voltage and constant current unit, wherein the input end of the power conversion unit is connected in parallel with the output end of the rectification module, the second output port of the power conversion unit is connected with the second protocol chip, and the constant voltage and constant current unit controls the power conversion unit to work in a constant voltage mode and a constant current mode.

The power conversion unit comprises a second transformer, a first end of a primary winding of the second transformer is connected with a first output end of the rectifying module,

An eighth diode, the anode of the eighth diode is connected with the second end of the primary winding of the transformer,

One end of the second resistor is connected with the cathode of the eighth diode, the other end of the second resistor is connected with the first end of the primary winding of the second transformer,

A fifth capacitor connected in parallel with two ends of the second resistor,

A seventh diode, an anode of the seventh diode is connected with a first end of a secondary winding of the second transformer, a cathode of the seventh diode is connected with the second output port,

A fourth capacitor, one end of which is connected with the cathode of the seventh diode, the other end of which is connected with the second end of the secondary winding of the second transformer and the second output port, the second output port is connected with the fourth capacitor in parallel, the fourth capacitor is connected with the second protocol chip,

A fourth switching tube, a first end of which is connected with the anode of the eighth diode, a second end of which is connected with the second output end of the rectifying module,

The third end of the fourth switching tube is connected with the pulse width modulation chip,

The optocoupler is connected between the pulse width modulation chip and the constant voltage and constant current unit.

The first DC-DC conversion module comprises a first transformer, a first end of a primary winding of the first transformer is connected with a first output end of the rectification module, a second end of a secondary winding of the first transformer is grounded,

A fifth diode, an anode of the fifth diode is connected with a second end of the primary winding of the first transformer,

One end of the first resistor is connected with the cathode of the fifth diode, the other end of the first resistor is connected with the first end of the primary winding of the first transformer,

The second capacitor is connected in parallel with the two ends of the first resistor,

A first switching tube, a first end of the first switching tube is connected with the anode of the fifth diode, a second end of the first switching tube is connected with the second output end of the rectifying module,

A sixth diode, an anode of the sixth diode is connected with a first end of the secondary winding of the first transformer, a cathode of the sixth diode is connected with the first output port,

One end of the third capacitor is connected with the cathode of the sixth diode, the other end of the third capacitor is connected with the second end of the secondary winding of the first transformer, the first output port is connected with the third capacitor in parallel, and the first output port is connected with the first protocol chip.

The rectifier module comprises two bridge arms and a first capacitor, wherein the two bridge arms are connected with the first capacitor in parallel, alternating current is input to the midpoint of the bridge arm, the bridge arm comprises two diodes, and the two diodes are connected in series in the same direction.

The constant voltage and constant current unit comprises a first operational amplifier, the output end of the first operational amplifier is connected with the optocoupler, the input negative end and the input positive end of the first operational amplifier are connected with the second protocol chip to receive a current reference value,

A third resistor, the negative input end of the first operational amplifier is connected with the second end of the secondary winding of the second transformer through the third resistor,

A fourth resistor and a sixth capacitor which are connected in series and then connected in parallel between the output end and the input negative end of the first operational amplifier,

The output end of the second operational amplifier is connected with the optocoupler, the input positive end of the second operational amplifier is connected with the second protocol chip and receives a voltage reference value,

A fifth resistor, the negative input end of the second operational amplifier is connected with the cathode of the seventh diode through the fifth resistor,

A sixth resistor through which the negative input terminal of the second operational amplifier is grounded,

A seventh resistor and a seventh capacitor which are connected in series and then connected in parallel between the output end and the input negative end of the second operational amplifier,

And the eighth capacitor is connected between the grounding end and the power supply end of the second operational amplifier, and the grounding end of the second operational amplifier is grounded through the eighth capacitor.

The constant voltage and constant current unit comprises a third resistor which is connected with the second output end in series,

One end of the fourth resistor is connected with the cathode of the seventh diode, the other end of the fourth resistor is connected with the optocoupler,

And the fifth resistor is connected with the sixth resistor in series and then connected with the second output end in parallel, and one end of the sixth resistor is connected with the input negative end of the second operational amplifier.

The invention also provides a control method of the multi-port output charger, which comprises the following steps,

Step S1, a first DC-DC conversion module is set to work in a constant-voltage mode, and a second DC-DC conversion module is set to work in a constant-current or constant-voltage mode;

S2, when the first output port and the second output port are both connected with a load, a second protocol chip is used for controlling the disconnection of a second switch, and the first DC-DC conversion module and the second DC-DC conversion module respectively supply power to the load;

Step S3, when the first output port is connected with a load and the second output port is not connected with the load, a second protocol chip is used for controlling a second switch to be closed, the second DC-DC conversion module works in a constant voltage mode, the output voltage is higher than the voltage of the first DC-DC conversion module, and the second DC-DC conversion module supplies power for the load; if the power of the second DC-DC conversion module does not meet the load requirement, the second DC-DC conversion module is switched to a constant current mode; the output voltage of the second DC-DC conversion module is equal to the voltage of the first DC-DC conversion module, and the second DC-DC conversion module and the first DC-DC conversion module jointly supply power to a load.

S4, when the first output port is not connected with a load and the second output port is connected with the load, a second protocol chip is used for controlling the second switch to be closed, the second DC-DC conversion module works in a constant voltage mode, and the output voltage is higher than the voltage of the first DC-DC conversion module; and if the power of the second DC-DC conversion module does not meet the load requirement, the second DC-DC conversion module is switched to a constant current mode. The output voltage of the second DC-DC conversion module is equal to the voltage of the first DC-DC conversion module, and the second DC-DC conversion module and the first DC-DC conversion module jointly supply power to a load.

In the technical scheme, two DC-DC conversion modules are adopted to provide energy for a load; the protocol chip is used for controlling one DC-DC conversion module to work in a constant voltage mode, so that the other DC-DC conversion module works in a constant voltage or constant current mode, and the output voltage of the second DC-DC conversion module is controlled to be slightly higher than that of the first DC-DC conversion module; the principle that the constant current source and the constant voltage source can be directly connected in parallel is utilized, so that the two DC-DC conversion modules are connected in parallel to supply power for a load together. And controls whether the output ends of the two DC-DC conversion modules are connected in parallel through a second switch.

In summary, the multi-port output charger and the control method thereof have the advantages of simple structure, high working efficiency and high reliability, and simultaneously solve the problem that a single flyback conversion module is easy to concentrate heat.

Drawings

Fig. 1 is a block diagram showing a multi-port output charger according to the prior art.

Fig. 2 shows a block diagram of an embodiment of the invention.

Fig. 3 shows a first embodiment of a multiple-port output charger according to the present invention.

Fig. 4 shows a second embodiment of the multi-port output charger of the present invention.

Fig. 5 shows a third embodiment of the multi-port output charger of the present invention.

Fig. 6 is a flowchart showing a control method of the multi-port output charger according to the present invention.

Reference numerals illustrate:

11. 21, 31, 41, 51-rectifying module; 12. 22, 32, 42, 52-a first DC-DC conversion module; 23. 33, 43, 53-a second DC-DC conversion module; 331. 431, 531-power conversion units; 3311. 4311, 5311-pulse width modulation chips; 3312. 4312, 5312-optocouplers; 332. 432, 532-constant voltage constant current units; 14. 24, 34, 44, 54-control output module; 141-a first dc-dc converter; 142. 242, 342, 442, 542—first protocol chip; 143-a second dc-dc converter; 144. 244, 344, 444, 544-second protocol chips.

Detailed Description

The technical scheme of the present invention will be clearly and completely described in the following with reference to the accompanying drawings of the embodiments of the present invention. It will be apparent that the described embodiments are some, but not all, embodiments of the invention. All other embodiments, which can be made by a person skilled in the art without creative efforts, based on the described embodiments of the present invention fall within the protection scope of the present invention.

As shown in fig. 2, the multi-port output charger of the present invention includes a rectifying module 21, a first DC-DC converting module 22, a second DC-DC converting module 23, and a control output module 24, where an alternating current u _in is rectified by the rectifying module 21 to obtain a direct current V _dc1, and the direct current V _dc1 is a pulsating high voltage direct current. The first DC-DC conversion module 22 and the second DC-DC conversion module 23 are connected in parallel to the output port of the rectifying module 21, the direct current V _dc1 is input to the first DC-DC conversion module 22 and the second DC-DC conversion module 23 respectively, the first DC-DC conversion module 22 and the second DC-DC conversion module 23 output voltage V _{out_C1} and voltage V _{out_C2} respectively, and the first DC-DC conversion module 22 and the second DC-DC conversion module 23 are connected to the control output module 24.

It should be noted that the first DC-DC conversion module 22 operates in a constant voltage mode, and the second DC-DC conversion module 23 may operate in a constant voltage mode or a constant current mode.

Optionally, the first DC-DC conversion module 22 and the second DC-DC conversion module 23 are flyback conversion modules or resonant conversion modules or forward conversion modules, and the present invention is described using flyback conversion modules, but not limited thereto.

The control output module 24 includes a first protocol chip 242, a switch Q ₂, and a second protocol chip 244, where the port 1 of the first protocol chip 242 is connected to the first output end P1 of the first DC-DC conversion module 22, the first protocol chip 242 performs power distribution and voltage regulation to obtain a voltage required by the first output end P1, the first end of the switch Q ₂ is connected to the first output end P1, the second end of the switch Q ₂ is connected to the second output end P2, the port 1 of the second protocol chip 244 is connected to the third end of the switch Q ₂, the port 1 of the second protocol chip 244 is connected to the second output end P2 of the second DC-DC conversion module 23, the second protocol chip 244 performs power distribution and voltage regulation to obtain electric energy of the second output end P2, and the two protocol chips communicate with each other to control the switch Q ₂ to be turned off, and when the switch Q ₂ is turned on, the first DC-DC conversion module 22 and the second DC conversion module 23 can simultaneously provide electric energy to the second DC conversion module 23.

Optionally, the switch Q ₂ is a bidirectional switch.

Fig. 6 is a flowchart of a control method of a multi-port output charger according to the present invention, and fig. 2 is a flowchart illustrating a control method according to a technical solution of the present invention, where the control method includes:

Step S1, a first DC-DC conversion module is set to work in a constant-voltage mode, and a second DC-DC conversion module is set to work in a constant-current or constant-voltage mode;

Step S2, when the first output port and the second output port are both connected with a load, the second protocol chip controls the switch Q2 to be disconnected, and the first DC-DC conversion module and the second DC-DC conversion module respectively supply power to the load;

Step S3, when the first output port is connected with a load and the second output port is not connected with the load, the second protocol chip controls the switch Q2 to be closed, the second DC-DC conversion module works in a constant voltage mode, and the output voltage is slightly higher than that of the first DC-DC conversion module, so that the first DC-DC conversion module works in an idle state, and the second DC-DC conversion module supplies power for the load connected with the first output port; if the power of the second DC-DC conversion module does not meet the requirement that the first output port is connected with a load, the second DC-DC conversion module is switched to a constant-current mode, the first DC-DC conversion module works in a constant-voltage mode, the second DC-DC conversion module is connected with the output end of the first DC-DC conversion module in parallel, the output voltage of the second DC-DC conversion module is equal to the output voltage of the first DC-DC conversion module, and the first DC-DC conversion module and the second DC-DC conversion module supply power for the load simultaneously;

Step S4, when the first output port is not connected with a load and the second output port is connected with the load, the second protocol chip controls the switch Q2 to be closed, the second DC-DC conversion module works in a constant voltage mode, the output voltage is slightly higher than that of the first DC-DC conversion module, and the second DC-DC conversion module supplies power for the load; if the power of the second DC-DC conversion module does not meet the load requirement, the second DC-DC conversion module is switched to a constant current mode, the output voltage of the second DC-DC conversion module is equal to the output voltage of the first DC-DC conversion module, and the first DC-DC conversion module and the second DC-DC conversion module supply power for the load simultaneously.

The first and second protocol chips detect the load connection state of the first and second output ports and the power condition of the load, respectively, and communicate with each other.

For example, the maximum total output power of the charger of the present invention is 65W, the first DC-DC conversion module 22 is designed with 20W power, and the second DC-DC conversion module 23 is designed with 45W power.

The second output port P2 is connected to a load, the power required by the load is more than 45W, the first output port P1 is not connected to the load, the switch Q2 is closed, the output ends of the two DC-DC conversion modules are connected in parallel, the second DC-DC conversion module is controlled by the second protocol chip to work in a constant current mode, the first DC-DC conversion module is controlled by the second protocol chip to work in a constant voltage mode, the maximum output voltage of the second DC-DC conversion module is equal to the output voltage V _{out_C1} of the first DC-DC conversion module, and at the moment, the two DC-DC conversion modules jointly supply energy to the load to control the switch Q ₂ to be in a conducting state.

The second output port P2 is connected to a load, the power required by the load is not more than 45W, the first output port P1 is not connected to the load, the switch Q2 is closed, the output ends of the two DC-DC conversion modules are connected in parallel, only the second DC-DC conversion module is needed to supply energy to the load, at this time, the second DC-DC conversion module works in a constant voltage mode, and the output voltage V _{out_C2} of the second DC-DC conversion module is controlled to be slightly higher than the voltage V _{out_C1}, so that the first DC-DC conversion module cannot supply energy to the load.

For example, the first DC-DC conversion module has a power of 20W, and operates in a constant voltage mode with a voltage of 20V. The power of the second DC-DC conversion module is 45W, and the second DC-DC conversion module works in a constant voltage and constant current mode, and the voltage is set to be 20.5V when the second DC-DC conversion module is connected in parallel. When the load is smaller than 45W, the load voltage is 20.5V, and the load power is provided by the second DC-DC conversion module, and the first DC-DC conversion module is empty. When the required load is greater than 45W, the second DC-DC conversion module is switched to a constant current mode. The output voltage of the second DC-DC conversion module is equal to the output voltage of the first DC-DC conversion module, and the output voltage is used for supplying power to a load at the moment, and the load voltage is 20V.

As shown in fig. 3, the multi-port output charger of the present invention provides a specific structure of a rectifying module 31, a first DC-DC converting module 32, and the second DC-DC converting module 33 based on the circuit in fig. 2; in this embodiment, the switch Q ₂ is a bidirectional combined switch, including a switch tube Q ₂₁ and a switch tube Q ₂₂, a drain electrode of the switch tube Q ₂₁ is connected to the port 1 of the first protocol chip 342, a source electrode of the switch tube Q ₂₁ is connected to the source electrode of the switch tube Q ₂₂, gates of the switch tube Q ₂₁ and the switch tube Q ₂₂ are commonly connected to the port 3 of the second protocol chip 344, and a port 1 and a port 4 of the second protocol chip 344 are commonly connected to the drain electrode of the switch tube Q ₂₂.

Optionally, the switching tube Q ₂₁ and the switching tube Q ₂₂ are N-type MOSFETs.

The rectifying module 31 includes a diode D ₁~D₄ and a capacitor C ₁, where the diode D ₂ and the diode D ₁ are connected in series in the same direction to form a first bridge arm, the diode D ₄ and the diode D ₃ are connected in series in the same direction to form a second bridge arm, the second bridge arm is connected in parallel with the first bridge arm, an alternating current u _in is input between a bridge arm midpoint of the second bridge arm and a bridge arm midpoint of the first bridge arm, the capacitor C ₁ is connected in parallel with the second bridge arm, a first end of the capacitor C ₁ is connected with the diode D ₁ and a cathode of the diode D ₃, a second end of the capacitor C ₁ is connected with the diode D ₂ and an anode of the diode D ₄, a second end of the capacitor C ₁ is grounded, and the capacitor C ₁ is used for storing electric energy.

Optionally, the capacitor C ₁ is an electrolytic capacitor.

The first DC-DC conversion module 32 comprises a capacitor C ₂~C₃, a resistor R ₁, a diode D ₅~D₆, a switching tube Q ₁ and a transformer T ₁, The opposite end (end without black point) of the primary winding of the transformer T ₁ is connected to the first end of the capacitor C ₁, the anode of the diode D ₅ is connected to the same end (end with black point) of the primary winding of the transformer T ₁, The cathode of the diode D ₅ is connected with one end of the resistor R ₁, the other end of the resistor R ₁ is connected with the synonym end of the primary winding of the transformer T ₁, The capacitor C ₂ is connected in parallel with two ends of the resistor R ₁, the drain electrode of the switching tube Q ₁ is connected with the anode of the diode D ₅, a source electrode of the switch tube Q ₁ is connected with a second end of the capacitor C ₁, a homonymous end of a secondary winding of the transformer T ₁ is connected with an anode of the diode D ₆, The cathode of the diode D ₆ is the first output terminal of the first DC-DC conversion module 32, which outputs the voltage V _{out_C1}, the cathode of the diode D ₆ is connected to one end of the capacitor C ₃, The other end of the capacitor C ₃ is connected with the synonym end of the secondary winding of the transformer T ₁, and the synonym end of the secondary winding of the transformer T ₁ is connected with the ground end SGND.

Optionally, the switching tube Q ₁ is an N-type MOSFET.

The second DC-DC conversion module 33 includes a power conversion unit 331 and a constant voltage and constant current unit 332, the power conversion unit 331 is connected in parallel to the output end of the rectification module 31, a first port of the constant voltage and constant current unit 332 is connected to the power conversion unit 331, and a second port of the constant voltage and constant current unit 332 is connected to the control output module 34.

The power conversion unit 331 includes a pulse width modulation chip 3311, a capacitor C ₄~C₅, a resistor R ₂, a diode D ₇~D₈, a switching tube Q ₄, Transformer T ₂ and optocoupler 3312, the synonym end of the primary winding of transformer T ₂ is connected with the first end of capacitor C ₁, the anode of diode D ₈ is connected with the synonym end of the primary winding of transformer T ₂, one end of the resistor R ₂ is connected with the cathode of the diode D ₈, the other end of the resistor R ₂ is connected with the synonym end of the primary winding of the transformer T ₂, The capacitor C ₅ is connected in parallel with two ends of the resistor R ₂, the homonymous end of the secondary winding of the transformer T ₂ is connected with the anode of the diode D ₇, The cathode of the diode D ₇ is the first output terminal of the second DC-DC conversion module 33, which outputs the voltage V _{out_C2}, the first terminal of the capacitor C ₄ is connected to the cathode of the diode D ₇, The second end of the capacitor C ₄ is connected with the synonym end of the secondary winding of the transformer T ₂, the synonym end of the secondary winding of the transformer T ₂ is connected with the ground end SGND ₁, The drain of the switch Q ₄ is connected to the anode of the diode D ₈, the source of the switch Q ₄ is grounded, the gate of the switch Q ₄ is connected to the port 1 of the pulse width modulation chip 3311, The port 2 of the pulse width modulation chip 3311 is connected to the port 1 of the optocoupler 3312, the port 2 of the optocoupler 3312 is connected to one end of the constant voltage and constant current unit 332, and the other two ends of the constant voltage and constant current unit 332 are connected to the control output module 34.

Optionally, the switching tube Q ₄ is an N-type MOSFET.

In the embodiment of the present invention, when the second DC-DC conversion module 33 is operated in the constant voltage mode, the output voltage thereof is greater than the output voltage of the first DC-DC conversion module 32, and the diode D6 is turned off, so that the first DC-DC conversion module is operated in the idle state; when the second DC-DC conversion module 33 operates in the constant current mode, the output voltage of the second DC-DC conversion module 33 is equal to the output voltage of the first DC-DC conversion module, and the diode D6 is turned on.

As shown in fig. 4, the multi-port output charger of the present invention provides a specific structure of the constant voltage and constant current unit 432 based on the circuit in fig. 3, which comprises a resistor R ₃~R₇, a capacitor C ₆~C₈ and an operational amplifier a ₁~A₂, wherein the output end of the operational amplifier a ₁ is connected to the port 2 of the optocoupler 4312, The negative input terminal of the operational amplifier A ₁ is connected to the ground terminal SGND, the negative input terminal of the operational amplifier A ₁ is connected to the second terminal of the capacitor C ₄ through the resistor R ₃, One end of the resistor R ₄ is connected with the output end of the operational amplifier A ₁, the other end of the resistor R ₄ is connected with one end of the capacitor C ₆, The other end of the capacitor C ₆ is connected to the negative input terminal of the operational amplifier a ₁, the port 5 of the second protocol chip 444 outputs a current reference value cc_ref to the positive input terminal of the operational amplifier a ₁, the current reference value cc_ref, And setting a constant current loop reference, and changing through the second protocol chip. The output end of the operational amplifier A ₂ is connected with the port 2 of the optical coupler 4312, the input negative end of the operational amplifier A ₂ is connected with the cathode of the diode D ₇ through the resistor R ₅, one end of the resistor R ₇ is connected with the output end of the operational amplifier A ₂, the other end of the resistor R ₇ is connected with one end of the capacitor C ₇, The other end of the capacitor C ₇ is connected with the input negative end of the operational amplifier A ₂, the input negative end of the operational amplifier A ₂ is connected with the ground end SGND ₁ through the resistor R ₆, The output voltage reference value cv_ref of the port 6 of the second protocol chip 444 is input to the input positive terminal of the operational amplifier a ₂, and the voltage reference value cv_ref is set to a constant voltage loop reference, and can be changed by a protocol IC. The ground terminal of the operational amplifier A ₂ is connected to the first terminal of the capacitor C ₈, the second terminal of the capacitor C ₈ is connected to the power supply terminal of the operational amplifier A ₂, The voltage V _{out_C2} is input to the first terminal of the capacitor C ₈, and the second terminal of the capacitor C ₈ is connected to the ground terminal SGND ₁.

As shown in fig. 5, the multi-port output charger of the present invention provides another specific structure of the constant voltage and constant current unit 532 based on the circuit in fig. 3, which includes a resistor R ₃~R₅, a first end of the resistor R ₄ is connected to the cathode of the diode D ₇, a second end of the resistor R ₄ is connected to the port 2 of the optocoupler 5312, a first end of the resistor R ₃ is connected to the first end of the resistor R ₄, the resistor R ₃ samples the output voltage of the power conversion unit 531, that is, the voltage V _{out_C2}, a second end of the resistor R ₃ outputs a corresponding sampling value V _{out_C2_S} and is connected to the port 6 of the second protocol chip 544, the cathode of the diode D ₇ is connected to the port 1 of the second protocol chip 544 through the resistor R ₅, and the resistor R ₅ is used for detecting the output current of the power conversion unit 531. In this embodiment, the second protocol chip 544 has an operational amplifier built therein, and the second protocol chip 544 may have an integrated operational amplifier and an analog-to-digital conversion function.

In summary, when the power required by the load is larger, the invention adopts two DC-DC conversion modules to provide energy for the load, so that the heat generated in the working process is dispersed, the problem that the prior art in FIG. 1 is easy to concentrate heat is solved, and the working efficiency and the reliability are greatly improved; the current reference value and the voltage reference value of the second DC-DC conversion module are changed through the second protocol chip, the first DC-DC conversion module is controlled to work in a constant voltage mode, and the principle that a constant current source and a constant voltage source can be directly connected in parallel is utilized, so that the second DC-DC conversion module works in a constant voltage or constant current mode, and the maximum output voltage of the second DC-DC conversion module is slightly higher than the output voltage of the first DC-DC conversion module when the second DC-DC conversion module works in the constant voltage mode; and whether the output ends of the two DC-DC conversion modules are connected in parallel or not is controlled through the switch Q ₂ (comprising the switch tube Q ₂₁ and the switch tube Q ₂₂), so that the circuit design is ingenious, the DC-DC conversion modules for power supply can be flexibly selected according to the load types, the equivalent effect of dual-machine backup is achieved, the utilization rate of a single DC-DC conversion module is reduced, and the overall service life of the PD charger is prolonged.

The above-described embodiments take the example that the first DC-DC conversion module operates in the constant voltage mode and the second DC-DC conversion module switches between the constant voltage mode and the constant current mode, however, the second DC-DC conversion module may operate in the constant voltage mode as the case may be, and the first DC-DC conversion module switches between the constant voltage mode and the constant current mode.

It should be understood that the foregoing detailed description of the present invention is provided for illustration only and is not limited to the technical solutions described in the embodiments of the present invention, and those skilled in the art should understand that the present invention may be modified or substituted for the same technical effects; as long as the use requirement is met, the invention is within the protection scope of the invention.