WO2018170717A1 - Power supply circuit having adjustable output voltage and electrical connector - Google Patents

Abstract

A power supply circuit having an adjustable output voltage, said power supply circuit having an adjustable output voltage comprising: a bridge rectifier module (100), a pulse-width modulation (PWM) rectifier control module (200), a step-down chopper module (300), and a PWM step-down control module (400). The PWM rectifier control module outputs a PWM control signal to control the bridge rectifier module to convert an alternating current into a direct current; the step-down chopper module steps down the direct current and then outputs a direct current supply voltage to supply power to an accessed load; the PWM step-down control module adjusts the duty ratio of the PWM control signal according to the direct current supply voltage and a direct current flow which are outputted by the step-down chopper module so as to adjust the amplitude of the direct current supply voltage by means of controlling the on-off time of the step-down chopper module. Further comprised is an electrical connector, which comprises the power supply circuit having an adjustable output voltage. The present invention achieves an adjustable output voltage of a power supply circuit, and an outputted direct current power supply voltage may directly supply power to a load.

Description

 Power supply circuit and electrical connector with adjustable output voltage

Technical field

The invention relates to the technical field of electrical appliances, in particular to a power supply circuit and an electrical connector with adjustable output voltage.

Background technique

When using various household appliances, most of them use electric equipment to connect 50Hz and 220V AC voltage lines, but at the same time there are some special power equipments whose rated power supply voltage is less than 220V. For example, the charging voltage of mobile equipment is below 10V. Devices often require a corresponding adapter plug to change the voltage and reduce its input voltage to a suitable range. If the voltage applied to the consumer equipment exceeds its rated supply voltage, a breakdown effect will occur, damaging the consumer.

The existing socket generally has a relatively simple structure function, and the power supply voltage outputted by the internal power supply circuit of the socket is not adjustable, and can only function to connect the power supply device to the internal power supply circuit of the socket. In actual applications, an additional adapter is needed to output the socket. The AC power is rectified, filtered, and stepped down to be connected to the powered device, and the DC supply voltage output from the existing internal power supply circuit of the adapter is not adjustable. In the prior art, there is a problem that the power supply voltage outputted by the power supply circuit of the socket is not adjustable by the voltage regulating socket with adjustable output voltage. However, the voltage outputted by the power supply circuit of the voltage regulating socket is still an alternating voltage, and cannot be directly used for the power device. powered by.

Summary of the invention

The main object of the present invention is to solve the technical problem that the power supply voltage outputted by the power supply circuit in the prior art is not adjustable and cannot directly supply power to the powered device.

To achieve the above object, the present invention provides a power supply circuit with an adjustable output voltage, the power supply circuit of the adjustable output voltage comprising:

a bridge rectifier module for connecting to a power grid, converting AC power input from the power grid into direct current power;

a PWM rectification control module is connected to the bridge rectifier module, and is configured to provide a PWM control signal to control an on/off state of the bridge rectifier module;

The step-down chopper module is connected to the bridge rectifier module, and is configured to: step down the DC power outputted by the bridge rectifier module, and output a DC power supply voltage to supply power to the load;

a PWM step-down control module, coupled to the step-down chopper module, configured to adjust a duty ratio of the PWM control signal according to a DC supply voltage and a DC current output by the step-down chopper module to control the step-down The on-off time of the chopper module is used to adjust the amplitude of the DC supply voltage.

Preferably, the bridge rectifier module includes a first power switch, a second power switch, a third power switch, and a fourth power switch;

The controlled end of the first power switch, the controlled end of the second power switch, the controlled end of the third power switch, the controlled end of the fourth power switch, and the PWM rectification control, respectively The PWM control signal output of the module is connected;

The first connection end of the first power switch and the first connection end of the third power switch are all connected to the step-down chopper module; the second connection end of the first power switch is opposite to the second a first connection end of the power switch is connected and connected to an AC input end of the power grid; a second connection end of the third power switch is connected to the fourth connection end of the second power switch, and another The AC input terminal is connected; the second connection end of the second power switch and the second connection end of the fourth power switch are both grounded.

Preferably, the first power switch, the second power switch, the third power switch and the fourth power switch are all thyristors, the gate of the thyristor is a controlled end of the power switch, and the cathode of the thyristor is a power switch a first connection end, the anode of the thyristor is a second connection end of the power switch; or

The first power switch, the second power switch, the third power switch, and the fourth power switch are all transistors, the gate of the transistor is a controlled end of the power switch, and the collector of the transistor is the first of the power switch At the connection end, the transistor emits a second connection end of the power switch.

Preferably, the step-down chopper module comprises a switch tube, a diode, an inductor and a first capacitor;

a gate of the switch tube is connected to the PWM step-down control module, a collector of the switch tube is connected to the bridge rectifier module, and an emitter of the switch tube is connected to a cathode of the diode, and The first end of the inductor is connected; the anode of the diode is grounded, the second end of the inductor is connected to the anode of the first capacitor, the cathode of the first capacitor is grounded, and the anode of the first capacitor is used Connect to the load.

Preferably, the PWM step-down control module comprises:

a voltage control unit, coupled to the step-down chopper module, configured to sample the DC supply voltage to obtain a feedback voltage, and compare and amplify the feedback voltage with a reference voltage to output a reference current;

a current control unit, respectively connected to the voltage control unit and the step-down chopper module, for sampling a direct current in the step-down chopper module to obtain a feedback current, and the feedback current and the The reference current is compared and amplified to output a modulated wave;

a driving unit, respectively connected to the current control unit and the step-down chopper module, configured to synchronously carrier-modulate the modulated wave with a reference carrier, and output a PWM control signal to control on-off of the step-down chopper module time.

Preferably, the voltage control unit includes a reference voltage input terminal, a first amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, and a second capacitor;

One end of the first resistor is connected to the step-down chopper module, the other end of the first resistor is grounded via the second resistor, and an inverting input is input to the first amplifier via the third resistor End connection

The non-inverting input end of the first amplifier is connected to the reference voltage input end, and the output end of the first amplifier is connected to the current control unit;

One end of the second capacitor is connected to an inverting input end of the first amplifier, and the other end of the second capacitor is connected to one end of the fourth resistor, and the other end of the fourth resistor is opposite to the first The output of an amplifier is connected.

Preferably, the current control unit includes a second amplifier, a fifth resistor, a sixth resistor, and a third capacitor;

a non-inverting input of the second amplifier is coupled to an output of the voltage control unit, and an inverting input of the second amplifier is coupled to the buck chopper module via the fifth resistor, the second An output of the amplifier is connected to the driving unit;

One end of the third capacitor is connected to an inverting input end of the second amplifier, and the other end of the third capacitor is connected to one end of the sixth resistor, and the other end of the sixth resistor is opposite to the first The output of the two amplifiers is connected.

Preferably, the driving unit comprises a carrier input terminal, a comparator and a seventh resistor;

An inverting input of the comparator is coupled to an output of the current control unit, an inverting input of the comparator is coupled to the carrier input, and an output of the comparator is coupled to the seventh resistor The step-down chopper module is connected.

In addition, in order to achieve the above object, the present invention further provides an electrical connector including a power supply circuit with an adjustable output voltage, the power supply circuit of the adjustable output voltage comprising:

a bridge rectifier module for connecting to a power grid, converting AC power input from the power grid into direct current power;

a PWM rectification control module is connected to the bridge rectifier module, and is configured to provide a PWM control signal to control an on/off state of the bridge rectifier module;

The step-down chopper module is connected to the bridge rectifier module, and is configured to: step down the DC power outputted by the bridge rectifier module, and output a DC power supply voltage to supply power to the load;

a PWM step-down control module, coupled to the step-down chopper module, configured to adjust a duty ratio of the PWM control signal according to a DC supply voltage and a DC current output by the step-down chopper module to control the step-down The on-off time of the chopper module is used to adjust the amplitude of the DC supply voltage.

The invention can realize the beneficial effects: the technical scheme of the invention controls the bridge rectifier module to convert the alternating current into the direct current by the PWM rectification output PWM control signal control module, and the step-down chopper module depressurizes the direct current outputted by the bridge rectifier module. The output DC power supply voltage supplies power to the connected load, and then adjusts the duty ratio of the PWM control signal according to the DC supply voltage and the DC current output by the PWM step-down control module to control the step-down chopper The on-off time of the module is used to adjust the magnitude of the DC supply voltage. Therefore, when the power supply circuit is connected to the load of different rated power supply voltage (ie, the electric equipment), the DC power supply voltage of different amplitudes can be output according to the connected load to supply power to the load, thereby achieving the adjustable output voltage of the power supply circuit. Moreover, the output DC power supply voltage can directly supply power to the load. The adjustable output voltage power supply circuit of the invention can be applied to an electrical connector to achieve an adjustable output voltage, and the output voltage can directly supply power to the load.

DRAWINGS

1 is a schematic block diagram of an embodiment of a power supply circuit with adjustable output voltage according to the present invention;

2 is a schematic diagram showing the circuit structure of an embodiment of a power supply circuit with adjustable output voltage according to the present invention.

The implementation, functional features, and advantages of the present invention will be further described in conjunction with the embodiments.

detailed description

The preferred embodiments of the present invention are described in conjunction with the accompanying drawings, and the preferred embodiments described herein are intended to illustrate and explain the invention, and not to limit the invention, and The embodiments and the features in the embodiments can be combined with each other.

The invention provides a power supply circuit with an adjustable output voltage.

Referring to FIG. 1, FIG. 1 is a schematic block diagram of an embodiment of a power supply circuit with adjustable output voltage according to the present invention.

In an embodiment, as shown in FIG. 1 , the adjustable output voltage power supply circuit includes a bridge rectifier module 100 , a PWM rectifier control module 200 , a step-down chopper module 300 , and a PWM step-down control module 400 . The bridge rectifier module 100 is configured to be connected to the power grid, and converts the AC power input by the power grid into DC power. The PWM rectifier control module 200 is connected to the bridge rectifier module 100 for providing a PWM control signal to control the on/off of the bridge rectifier module 100. The step-down chopper module 300 is connected to the bridge rectifier module 100 for stepping down the DC output of the bridge rectifier module 100 and outputting the DC supply voltage Vo to supply power to the load; the PWM step-down control module 400 and the buck The chopper module 300 is connected to adjust the duty ratio of the PWM control signal according to the DC supply voltage and the DC current output by the step-down chopper module 300 to adjust the DC supply voltage by controlling the on-off time of the step-down chopper module 300. The magnitude of the. Specifically, as shown in FIG. 1 , the input end of the bridge rectifier module 100 is used for connecting to the power grid, and the output end of the bridge rectifier module 100 is connected to the input end of the step-down chopper module 300 , and the output of the step-down chopper module 300 is output. For connecting to the load; the input end of the PWM rectification control module 200 is connected to the output end of the bridge rectifier module 100, and the output end of the PWM rectification control module 200 is connected to the control end of the bridge rectifier module 100; the PWM step-down control module 400 The input end is connected to the output end of the step-down chopper module 300, and the output end of the PWM step-down control module 400 is connected to the control end of the step-down chopper module 300.

When the power supply circuit with adjustable output voltage works normally, the power supply circuit that can adjust the output voltage is connected to the power grid and the load is connected. The 220V AC input from the power grid is input to the bridge rectifier module 100, and the bridge rectifier module 100 is 220V. The alternating current is rectified and converted to direct current. The PWM rectification control module 200 detects the DC power output by the bridge rectifier module 100, controls the on/off state of the bridge rectifier module 100 according to the DC output PWM control signal outputted by the bridge rectifier module 100, and then controls the bridge rectifier module 100 to convert the AC power into DC power. The step-down chopper module 300 steps down the direct current and outputs the direct current supply voltage to the connected load. The PWM step-down control module 400 outputs a PWM control signal according to the DC supply voltage and the direct current output of the step-down chopper module 300. The chopper module 300 is pressed and the duty ratio of the PWM control signal is adjusted, and the buck chopper module 300 is turned on and off according to the PWM control signal output by the PWM buck control module 400, and is adjusted according to the duty ratio of the PWM control signal. The on-off time, in turn, adjusts the magnitude of the output DC supply voltage.

Therefore, compared with the prior art, when the power supply circuit is connected to the load of different rated power supply voltages, the power supply circuit can output different magnitudes of the DC power supply voltage according to the connected load to supply power to the load, thereby achieving the output voltage of the power supply circuit. Adjustable, and realize the output of the DC supply voltage can directly supply power to the load.

Referring again to FIG. 2, FIG. 2 is a schematic diagram showing the circuit structure of an embodiment of a power supply circuit with adjustable output voltage according to the present invention.

As shown in FIG. 2, the bridge rectifier module 100 includes a first power switch VT1, a second power switch VT2, a third power switch VT3, and a fourth power switch VT4.

The controlled end of the first power switch VT1, the controlled end of the second power switch VT2, the controlled end of the third power switch VT3, the controlled end of the fourth power switch VT4, and the PWM control signal of the PWM rectification control module 200, respectively The output terminal is connected; the first connection end of the first power switch VT1 and the first connection end of the third power switch VT3 are connected to the step-down chopper module 300; the second connection end of the first power switch VT1 and the second power switch The first connection end of the VT2 is connected and connected to an AC input end of the power grid; the second connection end of the third power switch VT3 is connected to the fourth connection end of the second power switch VT2, and another AC input end of the power grid The second connection end of the second power switch VT2 and the second connection end of the fourth power switch VT4 are both grounded.

Specifically, the first power switch VT1, the second power switch VT2, the third power switch VT3, and the fourth power switch VT4 are all thyristors, such as a first power switch VT1, a second power switch VT2, a third power switch VT3, and a Four power switches VT4 are GTO (Gate Turn-Off Thyristor, the gate can turn off the thyristor), the gate of the thyristor is the controlled end of the power switch, the cathode of the thyristor is the first connection end of the power switch, and the anode of the thyristor is the second connection end of the power switch.

In another modified embodiment, the first power switch VT1, the second power switch VT2, the third power switch VT3, and the fourth power switch VT4 are all transistors, such as a first power switch VT1, a second power switch VT2, The three power switch VT3 and the fourth power switch VT4 are both IGBTs (Insulated Gate Bipolar Transistor, insulated gate bipolar transistor), the gate of the transistor is the controlled end of the power switch, the collector of the transistor is the first connection of the power switch, and the emitter of the transistor is the second connection of the power switch.

It should be understood by those skilled in the art that only the circuit structure when the first power switch VT1, the second power switch VT2, the third power switch VT3, and the fourth power switch VT4 are thyristors is given in FIG. 2, when the first power When the switch VT1, the second power switch VT2, the third power switch VT3, and the fourth power switch VT4 are all transistors, the thyristors may be replaced by transistors, and details are not described herein. In addition, it should be noted that the circuit structure of the PWM rectification control module 200 is not shown in FIG. 2, and the circuit structure of the PWM rectification control module 200 refers to the existing PWM rectification control circuit, and details are not described herein again.

As shown in FIG. 2, the step-down chopper module 300 includes a switching transistor Q1, a diode D1, an inductor L1, and a first capacitor C1.

The gate of the switch Q1 is connected to the PWM step-down control module 400, and the collector of the switch Q1 is connected to the bridge rectifier module 100, that is, the collector of the switch Q1 in FIG. 2 and the cathode of the first power switch VT1, respectively. The cathode of the third power switch VT3 is connected; the emitter of the switch Q1 is connected to the cathode of the diode D1 and is connected to the first end of the inductor L1; the anode of the diode D1 is grounded, the second end of the inductor L1 is connected to the first capacitor C1 The positive pole is connected, the negative pole of the first capacitor C1 is grounded, and the anode of the first capacitor C1 is used to be connected to the load Rload.

As shown in FIG. 2, the PWM step-down control module 400 includes a voltage control unit 410, a current control unit 420, and a driving unit 430.

The voltage control unit 410 is connected to the step-down chopper module 300 for sampling the DC supply voltage to obtain a feedback voltage, and comparing and amplifying the feedback voltage with the reference voltage to output a reference current.

The current control unit 420 is connected to the voltage control unit 410 and the step-down chopper module 300, respectively, for sampling the DC current in the step-down chopper module 300 to obtain a feedback current, and comparing and amplifying the feedback current with the reference current. The modulated wave is output.

The driving unit 430 is respectively connected to the current control unit 420 and the step-down chopper module 300 for synchronizing carrier modulation of the modulated wave with the reference carrier, and outputting the PWM control signal to control the on-off time of the step-down chopper module 300.

Specifically, the voltage control unit 410 includes a reference voltage input terminal REF1, a first amplifier U1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a second capacitor C2.

One end of the first resistor R1 is connected to the step-down chopper module 300, that is, one end of the first resistor R1 is connected to the anode of the first capacitor C1, and the other end of the first resistor R1 is grounded via the second resistor R2, and Connected to the inverting input terminal of the first amplifier U1 via the third resistor R3; the non-inverting input terminal of the first amplifier U1 is connected to the reference voltage input terminal REF1, and the output terminal of the first amplifier U1 is connected to the current control unit 420; the second capacitor One end of C2 is connected to the inverting input end of the first amplifier U1, the other end of the second capacitor C2 is connected to one end of the fourth resistor R4, and the other end of the fourth resistor R4 is connected to the output end of the first amplifier U1.

Specifically, the current control unit 420 includes a second amplifier U2, a fifth resistor R5, a sixth resistor R6, and a third capacitor C3.

The non-inverting input of the second amplifier U2 is connected to the output of the voltage control unit 410, that is, the non-inverting input of the second amplifier U2 is connected to the output of the first amplifier U1, and the inverting input of the second amplifier U2 is connected. Connected to the step-down chopper module 300 via the fifth resistor R5, that is, the inverting input terminal of the second amplifier U2 is connected to the emitter of the switching transistor Q1 and the cathode of the diode D1 via the fifth resistor R5, the second amplifier The output end of U2 is connected to the driving unit 430; one end of the third capacitor C3 is connected to the inverting input end of the second amplifier U2, the other end of the third capacitor C3 is connected to one end of the sixth resistor R6, and the other end of the sixth resistor R6 One end is connected to the output of the second amplifier U2.

Specifically, the driving unit 430 includes a carrier input terminal REF2, a comparator U3, and a seventh resistor R7.

The non-inverting input of the comparator U3 is connected to the output of the current control unit 420, that is, the non-inverting input of the comparator U3 is connected to the output of the second amplifier U2, and the inverting input and carrier input of the comparator U3 are connected. The terminal REF2 is connected, and the output terminal of the comparator U3 is connected to the step-down chopper module 300 via the seventh resistor R7, that is, the output terminal of the comparator U3 is connected to the gate of the switch transistor Q1 via the seventh resistor R7.

As shown in FIG. 2, the working principle of the power supply circuit with adjustable output voltage of the present invention is specifically described as follows:

The first power switch VT1, the second power switch VT2, the third power switch VT3, and the fourth power switch VT4 in the bridge rectifier module 100 constitute a single-phase bridge type full-controlled rectifier circuit, and the effective value of the bridge rectifier module 100 input grid The AC voltage of 220V, the first power switch VT1, the second power switch VT2, the third power switch VT3, and the fourth power switch VT4 are controlled to be turned on or off by the PWM rectification control module 200 outputting a PWM control signal. The PWM rectification control module 200 performs SPWM on the first power switch VT1, the second power switch VT2, the third power switch VT3, and the fourth power switch VT4 using a natural power method (Sinusoidal Pulse Width Modulation, sinusoidal pulse width modulation) control, as shown in FIG. 2, when the voltage at a is higher than the voltage at b, the PWM rectification control module 200 outputs a PWM control signal to control the first power switch VT1 and the fourth power switch VT4 to be turned on. On the contrary, when the voltage at b is higher than the voltage at a, the PWM rectification control module 200 outputs a PWM control signal to control the second power switch VT2 and the third power switch VT3 to be turned on. Therefore, in the bridge rectifier module 100, the on/off state of the first power switch VT1, the second power switch VT2, the third power switch VT3, and the fourth power switch VT4 is controlled by the PWM control signal outputted by the PWM rectification control module 200. The 220V AC is converted to DC.

The PWM step-down control module 400 uses the inner loop to control the current and the outer loop to control the voltage. Specifically, as shown in FIG. 2, the first resistor R1 and the second resistor R2 divide the DC power supply voltage Vo outputted by the step-down chopper module 300 to obtain a feedback voltage, and the feedback voltage is input to the first amplifier U1 through the third resistor R3. The inverting input terminal, the reference voltage input terminal REF1 inputs a reference voltage to the non-inverting input terminal of the first amplifier U1. The feedback voltage is compared with the reference voltage through the first amplifier U1 to obtain a voltage deviation value, and the deviation value of the feedback voltage from the reference voltage passes through the PI formed by the fourth resistor R4 and the second capacitor C2 (Proportional) The Integral, Proportional and Integral controller is amplified to form a reference current which is used as a reference value for the second amplifier U2, that is, the output of the first amplifier U1 outputs a reference current to the non-inverting input of the second amplifier U2.

The inverting input terminal of the second amplifier U2 samples the DC current in the step-down chopper module 300 through the fifth resistor R5 to obtain a feedback current, and the feedback current is compared with the reference current through the second amplifier U2 to obtain a current deviation value, and the feedback current The deviation value from the reference current is amplified by the PI controller constituted by the sixth resistor R6 and the third capacitor C3 to form a triangular wave as a modulated wave, that is, the output end of the second amplifier U2 outputs the modulated wave to the in-phase of the comparator U3. Input. The carrier input terminal REF2 inputs a carrier whose threshold value has been set to the inverting input terminal of the comparator U3, and the modulated wave and the carrier are synchronously carrier-modulated by the comparator U3 to form a fixed-frequency PWM wave, that is, the output end of the comparator U3. Output PWM control signal. The seventh resistor R7 is used as a driving device of the switching transistor Q1, and the PWM control signal output from the comparator U3 is driven to turn on or off by the seventh resistor R7.

In the step-down chopper module 300, the on-off time of the switching transistor Q1 can be changed by adjusting the duty ratio of the PWM control signal outputted by the comparator U3, so that the amplitude of the output voltage can be changed by changing the on-off time of the switching transistor Q1. value.

Specifically, as shown in FIG. 2, in the CCM mode (ie, continuous conduction mode), the relationship between the output voltage assignment of the step-down chopper module 300 and the input voltage assignment is:

Vo=DVi

Wherein, Vo is the output voltage of the step-down chopper module 300, that is, the DC supply voltage, D is the duty ratio of the PWM control signal, and Vi is the input voltage of the step-down chopper module 300.

In the DCM mode (ie, the discontinuous conduction mode), the relationship between the output voltage assignment of the step-down chopper module 300 and the assignment of the input voltage is:

Toff=[(Vi-Vo)/ Vo]* Ton

Wherein, Vo is the output voltage of the step-down chopper module 300, that is, the above-mentioned DC supply voltage, Vi is the input voltage of the step-down chopper module 300, Ton is the on-time of the switching transistor Q1, and Toff is the off-time of the switching transistor Q1. It can be seen from the formula that the DC supply voltage outputted by the step-down chopper module 300 can be changed by adjusting the on-time and the off-time of the switching transistor Q1, so that it can be applied to supply power to different loads.

The invention also provides an electrical connector comprising a power supply circuit with adjustable output voltage, the structure of the power supply circuit with adjustable output voltage and the beneficial effects brought about by the above embodiments, no longer Narration.

The electrical connector of the present invention may specifically be a socket or an adapter. When the electrical connector is a socket, the socket output voltage can be adjusted, and the adjustable output voltage is a DC power supply voltage, which can directly supply power to different rated supply voltage loads without using an adapter for switching. When the electrical connector is an adapter, the DC voltage of the adapter output can be adjusted to be suitable for charging with different rated supply voltages.

The above are only the preferred embodiments of the present invention, and are not intended to limit the scope of the invention, and the equivalent structure or equivalent process transformations made by the description of the present invention and the drawings are directly or indirectly applied to other related technical fields. The same is included in the scope of patent protection of the present invention.

Claims (10)

 A power supply circuit with adjustable output voltage, characterized in that the power supply circuit of the adjustable output voltage comprises: a bridge rectifier module for connecting to a power grid, converting AC power input from the power grid into direct current power; a PWM rectification control module is connected to the bridge rectifier module, and is configured to provide a PWM control signal to control an on/off state of the bridge rectifier module; The step-down chopper module is connected to the bridge rectifier module, and is configured to: step down the DC power outputted by the bridge rectifier module, and output a DC power supply voltage to supply power to the load; a PWM step-down control module, coupled to the step-down chopper module, configured to adjust a duty ratio of the PWM control signal according to a DC supply voltage and a DC current output by the step-down chopper module to control the step-down The on-off time of the chopper module is used to adjust the amplitude of the DC supply voltage. The adjustable output voltage power supply circuit of claim 1 , wherein the bridge rectifier module comprises a first power switch, a second power switch, a third power switch, and a fourth power switch; The controlled end of the first power switch, the controlled end of the second power switch, the controlled end of the third power switch, the controlled end of the fourth power switch, and the PWM rectification control, respectively The PWM control signal output of the module is connected; The first connection end of the first power switch and the first connection end of the third power switch are all connected to the step-down chopper module; the second connection end of the first power switch is opposite to the second a first connection end of the power switch is connected and connected to an AC input end of the power grid; a second connection end of the third power switch is connected to the fourth connection end of the second power switch, and another The AC input terminal is connected; the second connection end of the second power switch and the second connection end of the fourth power switch are both grounded. The power supply circuit with adjustable output voltage according to claim 2, wherein the first power switch, the second power switch, the third power switch and the fourth power switch are thyristors, and the gate of the thyristor is extremely a controlled end of the power switch, a cathode of the thyristor being a first connection end of the power switch, and an anode of the thyristor being a second connection end of the power switch; or The first power switch, the second power switch, the third power switch, and the fourth power switch are all transistors, the gate of the transistor is a controlled end of the power switch, and the collector of the transistor is the first of the power switch At the connection end, the transistor emits a second connection end of the power switch. The power supply circuit with adjustable output voltage according to claim 1, wherein the step-down chopper module comprises a switch tube, a diode, an inductor, and a first capacitor; a gate of the switch tube is connected to the PWM step-down control module, a collector of the switch tube is connected to the bridge rectifier module, and an emitter of the switch tube is connected to a cathode of the diode, and The first end of the inductor is connected; the anode of the diode is grounded, the second end of the inductor is connected to the anode of the first capacitor, the cathode of the first capacitor is grounded, and the anode of the first capacitor is used Connect to the load. The power supply circuit of the adjustable output voltage according to any one of claims 1 to 4, wherein the PWM step-down control module comprises: a voltage control unit, coupled to the step-down chopper module, configured to sample the DC supply voltage to obtain a feedback voltage, and compare and amplify the feedback voltage with a reference voltage to output a reference current; a current control unit, respectively connected to the voltage control unit and the step-down chopper module, for sampling a direct current in the step-down chopper module to obtain a feedback current, and the feedback current and the The reference current is compared and amplified to output a modulated wave; a driving unit, respectively connected to the current control unit and the step-down chopper module, configured to synchronously carrier-modulate the modulated wave with a reference carrier, and output a PWM control signal to control on-off of the step-down chopper module time. The power supply circuit with adjustable output voltage according to claim 5, wherein the voltage control unit comprises a reference voltage input terminal, a first amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, and Second capacitor One end of the first resistor is connected to the step-down chopper module, the other end of the first resistor is grounded via the second resistor, and an inverting input is input to the first amplifier via the third resistor End connection The non-inverting input end of the first amplifier is connected to the reference voltage input end, and the output end of the first amplifier is connected to the current control unit; One end of the second capacitor is connected to an inverting input end of the first amplifier, and the other end of the second capacitor is connected to one end of the fourth resistor, and the other end of the fourth resistor is opposite to the first The output of an amplifier is connected. The power supply circuit with adjustable output voltage according to claim 5, wherein the current control unit comprises a second amplifier, a fifth resistor, a sixth resistor and a third capacitor; a non-inverting input of the second amplifier is coupled to an output of the voltage control unit, and an inverting input of the second amplifier is coupled to the buck chopper module via the fifth resistor, the second An output of the amplifier is connected to the driving unit; One end of the third capacitor is connected to an inverting input end of the second amplifier, and the other end of the third capacitor is connected to one end of the sixth resistor, and the other end of the sixth resistor is opposite to the first The output of the two amplifiers is connected. The power supply circuit with adjustable output voltage according to claim 5, wherein the driving unit comprises a carrier input terminal, a comparator and a seventh resistor; An inverting input of the comparator is coupled to an output of the current control unit, an inverting input of the comparator is coupled to the carrier input, and an output of the comparator is coupled to the seventh resistor The step-down chopper module is connected. An electrical connector, comprising the power supply circuit of the adjustable output voltage of any one of claims 1 to 8. The electrical connector of claim 9 wherein said electrical connector is a socket or an adapter.