A switching linear composite power supply and control method

Abstract

The present invention provides a switching linear composite power supply and control method in the technical field of power supply equipment. The composite power supply includes a control module, a DC-DC power supply module, a linear adjustment module and a detection module; the output end of the DC-DC power supply module is connected to the input end of the linear adjustment module; the input end of the detection module is connected to the DC-DC power supply module and the linear adjustment module, and the output end is connected to the control module; the control module is connected to the DC-DC power supply module and the linear adjustment module. The advantages of the present invention are: greatly improving the thermal stability, output accuracy, working efficiency and application scope of the power supply.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply equipment, and in particular to a switching linear composite power supply and a control method thereof. Background Art

[0002] Switch Mode Power Supply (SMPS), also known as switching power supply or switching converter, is a high-frequency power conversion device and a type of power supply. Its function is to convert a voltage level into the voltage or current required by the user through different forms of architecture. Linear power supply first reduces the voltage amplitude of AC power through a transformer, then rectifies it through a rectifier circuit to obtain pulsed DC power, and then filters it to obtain a DC voltage with a small ripple voltage.

[0003] For DC voltage regulators, switching power supplies have the advantages of low power consumption and high efficiency, but they are greatly affected by electromagnetic interference, and the ripple coefficient is large, resulting in poor output accuracy and slow response; linear power supplies are less affected by electromagnetic interference and have stable output, but they have the disadvantages of low working efficiency and poor thermal stability. That is, both switching power supplies and linear power supplies have their own advantages and disadvantages, and the bus voltage Vbus of traditional switching power supplies and linear power supplies is a fixed output, which limits their scope of application.

[0004] Therefore, how to provide a switching linear composite power supply and a control method to improve the thermal stability, output accuracy, working efficiency and application scope of the power supply has become an urgent problem to be solved. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a switching linear composite power supply and a control method to improve the thermal stability, output accuracy, working efficiency and application scope of the power supply.

[0006] In a first aspect, the present invention provides a switching linear composite power supply, including a control module, a DC-DC power supply module, a linear adjustment module and a detection module;

[0007] The output end of the DC-DC power supply module is connected to the input end of the linear adjustment module; the input end of the detection module is connected to the DC-DC power supply module and the linear adjustment module, and the output end is connected to the control module; the control module is connected to the DC-DC power supply module and the linear adjustment module.

[0008] Further, the control module includes an MCU, a hardware multiplier, a digital-to-analog converter and a communication interface group;

[0009] One end of the hardware multiplier is connected to the MCU, and the other end is connected to the detection module; one end of the digital-to-analog converter is connected to the MCU, and the other end is connected to the linear adjustment module; the MCU is connected to the communication interface group and the detection module respectively;

[0010] The communication interface group includes an SPI interface, a UART interface, an IIC interface and an Ethernet interface.

[0011] Furthermore, the DC-DC power supply module includes a filter circuit and a switch adjustment circuit;

[0012] The switch adjustment circuit is connected to the filter circuit, the linear adjustment module, the control module and the detection module respectively.

[0013] Further, the filter circuit includes a capacitor C1, a capacitor C2, an inductor L1 and an inductor L2;

[0014] One end of the inductor L1 is connected to the capacitor C1, and the other end is connected to the capacitor C2 and the switch adjustment circuit; one end of the inductor L2 is connected to the capacitor C1, and the other end is connected to the capacitor C2 and the switch adjustment circuit;

[0015] The switch adjustment circuit includes a capacitor C3, a capacitor C4, a diode D1, an inductor L3 and a MOS tube Q1;

[0016] The D pole of the MOS tube Q1 is connected to the capacitor C3, the capacitor C2 and the inductor L1, the S pole is connected to the inductor L3 and the output end of the diode D1, and the G pole is connected to the control module; one end of the capacitor C4 is connected to the inductor L3 and the linear adjustment module, and the other end is connected to the input end of the diode D1, the capacitor C3, the capacitor C2, the inductor L2 and the linear adjustment module.

[0017] Furthermore, the linear adjustment module includes a capacitor C5, a capacitor C6 and a MOS tube Q2;

[0018] The D pole of the MOS tube Q2 is connected to the capacitor C5, the DC-DC power module and the detection module, the S pole is connected to the capacitor C6 and the detection module, and the G pole is connected to the control module; the capacitor C5 is connected to the capacitor C6 and the DC-DC power module.

[0019] Further, the detection module includes a current detection circuit, a linear voltage difference detection circuit, an output voltage detection circuit, a temperature detection circuit and a bus voltage detection circuit;

[0020] The input end of the current detection circuit is connected to the output end of the DC-DC power supply module, and the output end is connected to the control module; the input end of the linear voltage difference detection circuit is connected to the input end and the output end of the linear adjustment module, and the output end is connected to the control module; the input end of the output voltage detection circuit is connected to the output end of the linear adjustment module, and the output end is connected to the control module; the input end of the temperature detection circuit is connected to the linear adjustment module, and the output end is connected to the control module; the input end of the bus voltage detection circuit is connected to the output end of the DC-DC power supply module, and the output end is connected to the control module.

[0021] In a second aspect, the present invention provides a control method for a switching linear composite power supply, comprising the following steps:

[0022] Step S10, MCU receives power supply parameters sent by the host computer through the communication interface group; the power supply parameters include loading voltage Vset, loading current Iset, MOS tube Q2 voltage drop, maximum output voltage Vmax of the battery to be tested, MOS tube power lower limit, MOS tube power upper limit, temperature threshold, voltage threshold and current threshold;

[0023] Step S20, the filter circuit filters the DC voltage regulator and then inputs the filtered DC voltage regulator into the switch adjustment circuit;

[0024] Step S30, the MCU calculates the bus voltage Vbusset based on the voltage drop of the MOS tube Q2 and the maximum output voltage Vmax of the battery to be tested, and outputs a corresponding pulse width modulation signal to the MOS tube Q1 based on the bus voltage Vbusset, so that the MOS tube Q1 outputs the modulated power to the linear adjustment module;

[0025] Step S40: The MCU sends the loading voltage Vset and the loading current Iset to the linear modulation module through the digital-to-analog converter, and the linear modulation module linearly adjusts the input power supply based on the received loading voltage Vset and the loading current Iset;

[0026] Step S50, the detection module detects the input current Isensor of the linear adjustment module, the linear voltage difference Vmos of the MOS tube Q2, the output voltage Vout of the linear adjustment module, the temperature Tmos at both ends of the MOS tube Q2, and the bus voltage Vbus output by the switch adjustment circuit;

[0027] Step S60, the MCU calculates the power loss Pmos of the MOS tube Q2 based on the input current Isensor, the linear voltage difference Vmos, the output voltage Vout and the bus voltage Vbus, and adjusts the pulse width modulation signal of the MOS tube Q1 based on the power loss Pmos, the MOS tube power lower limit and the MOS tube power upper limit;

[0028] In step S70 , the MCU performs safety monitoring on the temperature Tmos, the output voltage Vout and the input current Isensor based on the temperature threshold, the voltage threshold and the current threshold.

[0029] Furthermore, in step S30, the calculation formula of the bus voltage is:

[0030] Vbusset = voltage drop of MOS tube Q2 + Vmax.

[0031] Furthermore, the step S60 specifically includes:

[0032] Step S61: The MCU calculates the power loss Pmos of the MOS tube Q2 based on the hardware multiplier using the input current Isensor and the linear voltage difference Vmos:

[0033] Pmos = Vmos * Isensor;

[0034] Alternatively, the power loss Pmos of the MOS tube Q2 is calculated using the input current Isensor, the output voltage Vout and the bus voltage Vbus:

[0035] Pmos = (Vout - Vbus) * Isensor;

[0036] Step S62, MCU determines whether the power loss Pmos is less than the lower limit of the MOS tube power. If so, the duty cycle of the pulse width modulation signal of the MOS tube Q1 is increased; if not, the process proceeds to step S63;

[0037] Step S63, the MCU determines whether the power loss Pmos is greater than the upper limit of the MOS tube power. If so, the duty cycle of the pulse width modulation signal of the MOS tube Q1 is reduced; if not, the process proceeds to step S70.

[0038] Furthermore, the step S70 is specifically as follows:

[0039] The MCU determines whether the temperature Tmos is greater than the temperature threshold, whether the output voltage Vout is greater than the voltage threshold, or whether the input current Isensor is greater than the current threshold. If so, the output of the switching linear composite power supply is turned off; if not, monitoring continues.

[0040] The advantages of the present invention are:

[0041] 1. By setting a detection module including a current detection circuit, a linear voltage difference detection circuit, an output voltage detection circuit, a temperature detection circuit and a bus voltage detection circuit, the detection module is used to detect the input current Isensor of the linear adjustment module, the linear voltage difference Vmos of the MOS tube Q2, the output voltage Vout of the linear adjustment module, the temperature Tmos at both ends of the MOS tube Q2 and the bus voltage Vbus output by the switch adjustment circuit in real time, so that the MCU can adjust the duty cycle of the pulse width modulation signal of the MOS tube Q1 in real time based on the detected data, that is, adjust the bus voltage Vbusset to reduce power loss, thereby greatly improving the working efficiency of the power supply and greatly improving the thermal stability of the power supply.

[0042] 2. By setting a digital-to-analog converter, the loading voltage Vset and loading current Iset received by the MCU are transmitted to the linear adjustment module, and then the output of the linear adjustment module is accurately controlled, which greatly improves the output accuracy of the power supply.

[0043] 3. The bus voltage Vbusset is calculated through the voltage drop of the MOS tube Q2 and the maximum output voltage Vmax of the battery to be tested, and then the output of the MOS tube Q1 is set based on the calculated bus voltage Vbusset to achieve dynamic adjustment of the bus voltage, thereby greatly improving the application range of the power supply, that is, adaptability.

[0044] 4. The MCU monitors the temperature Tmos, output voltage Vout and input current Isensor based on the temperature threshold, voltage threshold and current threshold respectively. When the threshold is exceeded, the output of the switching linear composite power supply is immediately shut down, thereby greatly improving safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The present invention will be further described below in conjunction with embodiments with reference to the accompanying drawings.

[0046] Figure 1 The invention discloses a circuit principle block diagram of a switching linear composite power supply.

[0047] Figure 2 It is a circuit principle block diagram of the detection module of the present invention.

[0048] Figure 3 It is a circuit diagram of the DC-DC power supply module and the linear adjustment module of the present invention.

[0049] Figure 4 The present invention is a flow chart of a control method of a switching linear composite power supply.

[0050] Marking Description:

[0051] 100-a switching linear composite power supply, 1-control module, 2-DC-DC power supply module, 3-linear adjustment module, 4-detection module, 21-filter circuit, 22-switch adjustment circuit, 11-MCU, 12-hardware multiplier, 13-digital-to-analog converter, 14-communication interface group, 141-SPI interface, 142-UART interface, 143-IIC interface, 144-Ethernet interface, 41-current detection circuit, 42-linear voltage difference detection circuit, 43-output voltage detection circuit, 44-temperature detection circuit, 45-bus voltage detection circuit. DETAILED DESCRIPTION

[0052] The technical solution in the embodiment of the present application has the following general idea: by setting a detection module 4 to detect in real time the input current Isensor of the linear adjustment module 3, the linear voltage difference Vmos of the MOS tube Q2, the output voltage Vout of the linear adjustment module 3, the temperature Tmos at both ends of the MOS tube Q2 and the bus voltage Vbus output by the switch adjustment circuit 22, the MCU11 can adjust the duty cycle of the pulse width modulation signal of the MOS tube Q1 in real time based on the detected data, that is, adjust the bus voltage Vbusset to reduce power loss, so as to improve the working efficiency and thermal stability of the power supply; by setting a digital-to-analog converter 13, the loading voltage Vset and loading current Iset received by the MCU11 are transmitted to the linear adjustment module 3, and then the output of the linear adjustment module 3 is accurately controlled to improve the output accuracy of the power supply; the bus voltage Vbusset is calculated by the voltage drop of the MOS tube Q2 and the maximum output voltage Vmax of the battery to be tested, and then the output of the MOS tube Q1 is set based on the calculated bus voltage Vbusset, that is, the bus voltage is dynamically adjusted to improve the application range of the power supply.

[0053] Please refer to Figures 1 to 4 As shown, a preferred embodiment of a switching linear composite power supply 100 of the present invention comprises a control module 1, a DC-DC power supply module 2, a linear adjustment module 3 and a detection module 4; the control module 1 is used to control the operation of the switching linear composite power supply 100; the DC-DC power supply module 2 is used to adjust a fixed DC voltage to a variable DC voltage; the linear adjustment module 3 is used to accurately adjust the output of the DC-DC power supply module 2 so that the input voltage and current reach the required value and accuracy; the detection module 4 is used to collect the input current Isensor of the linear adjustment module 3, the linear voltage difference Vmos of the MOS tube Q2, the output voltage Vout of the linear adjustment module 3, the temperature Tmos at both ends of the MOS tube Q2 and the bus voltage Vbus output by the switch adjustment circuit 22, and then perform system self-check and closed-loop control, that is, convert various analog signals into digital signals and transmit them to the MCU11;

[0054] The output end of the DC-DC power supply module 2 is connected to the input end of the linear adjustment module 3; the input end of the detection module 4 is connected to the DC-DC power supply module 2 and the linear adjustment module 3, and the output end is connected to the control module 1; the control module 1 is connected to the DC-DC power supply module 2 and the linear adjustment module 3.

[0055] The control module 1 includes an MCU 11, a hardware multiplier 12, a digital-to-analog converter 13 and a communication interface group 14; the digital-to-analog converter 13 is used to accurately control the output of the linear adjustment module 3; the hardware multiplier 12 is used to multiply the detection results of the current detection circuit 41 and the linear voltage difference detection circuit 42 to obtain the power loss Pmos of the MOS tube Q2; the MCU 11 is used to control the operation of the switching linear composite power supply 100. In specific implementation, it is sufficient to select an MCU that can realize this function from the prior art, and it is not limited to any model, such as the STM32F103 series MCU of ST Company, and the control program is well known to those skilled in the art, which can be obtained by those skilled in the art without creative labor;

[0056] One end of the hardware multiplier 12 is connected to the MCU 11, and the other end is connected to the detection module 4; one end of the digital-to-analog converter 13 is connected to the MCU 11, and the other end is connected to the linear adjustment module 3; the MCU 11 is connected to the communication interface group 14 and the detection module 4 respectively;

[0057] The communication interface group 14 includes an SPI interface 141 , a UART interface 142 , an IIC interface 143 and an Ethernet interface 144 ; the SPI interface 141 , the UART interface 142 , the IIC interface 143 and the Ethernet interface 144 are all connected to the MCU 11 .

[0058] The DC-DC power supply module 2 includes a filter circuit 21 and a switch adjustment circuit 22; the filter circuit 21 is used to remove high-frequency clutter and interference signals;

[0059] The switch adjustment circuit 22 is connected to the filter circuit 21 , the linear adjustment module 3 , the control module 1 and the detection module 4 respectively.

[0060] The filter circuit 21 includes a capacitor C1, a capacitor C2, an inductor L1 and an inductor L2;

[0061] One end of the inductor L1 is connected to the capacitor C1, and the other end is connected to the capacitor C2 and the switch adjustment circuit 22; one end of the inductor L2 is connected to the capacitor C1, and the other end is connected to the capacitor C2 and the switch adjustment circuit 22;

[0062] The switch adjustment circuit 22 includes a capacitor C3, a capacitor C4, a diode D1, an inductor L3 and a MOS transistor Q1; by adjusting the conduction time of the MOS transistor Q1, the switch linear composite power supply 100 can output variable voltage and current;

[0063] The D pole (drain) of the MOS tube Q1 is connected to the capacitor C3, the capacitor C2 and the inductor L1, the S pole (source) is connected to the inductor L3 and the output end of the diode D1, and the G pole (gate) is connected to the control module 1; one end of the capacitor C4 is connected to the inductor L3 and the linear adjustment module 3, and the other end is connected to the input end of the diode D1, the capacitor C3, the capacitor C2, the inductor L2 and the linear adjustment module 3.

[0064] The linear adjustment module 3 includes a capacitor C5, a capacitor C6 and a MOS transistor Q2; the MOS transistor Q2 is used to protect the circuit and adjust the constant voltage and constant current accuracy;

[0065] The D pole of the MOS tube Q2 is connected to the capacitor C5, the DC-DC power module 2 and the temperature detection circuit 41 of the detection module 4, the S pole is connected to the capacitor C6 and the temperature detection circuit 41 of the detection module 4, and the G pole is connected to the digital-to-analog converter 13 of the control module 1; the capacitor C5 is connected to the capacitor C6 and the DC-DC power module 2.

[0066] The detection module 4 includes a current detection circuit 41, a linear voltage difference detection circuit 42, an output voltage detection circuit 43, a temperature detection circuit 44 and a bus voltage detection circuit 45;

[0067] The input end of the current detection circuit 41 is connected to the output end of the DC-DC power supply module 2, and the output end is connected to the hardware multiplier 12 and the MCU11 of the control module 1; the input end of the linear voltage difference detection circuit 42 is connected to the input end and the output end of the linear adjustment module 3, and the output end is connected to the hardware multiplier 12 and the MCU11 of the control module 1; the input end of the output voltage detection circuit 43 is connected to the output end of the linear adjustment module 3, and the output end is connected to the control module 1; the input end of the temperature detection circuit 44 is connected to the linear adjustment module 3, and the output end is connected to the control module 1; the input end of the bus voltage detection circuit 45 is connected to the output end of the DC-DC power supply module 2, and the output end is connected to the control module 1.

[0068] A preferred embodiment of a control method of a switching linear composite power supply of the present invention comprises the following steps:

[0069] Step S10, MCU receives power supply parameters sent by the host computer through the communication interface group; the power supply parameters include loading voltage Vset, loading current Iset, MOS tube Q2 voltage drop, maximum output voltage Vmax of the battery to be tested, MOS tube power lower limit, MOS tube power upper limit, temperature threshold, voltage threshold and current threshold;

[0070] Step S20, the filter circuit filters the DC voltage regulator and then inputs the filtered DC voltage regulator into the switch adjustment circuit;

[0071] Step S30, the MCU calculates the bus voltage Vbusset based on the voltage drop of the MOS tube Q2 and the maximum output voltage Vmax of the battery to be tested, and outputs a corresponding pulse width modulation signal (PWM) to the MOS tube Q1 based on the bus voltage Vbusset, that is, controls the on-time of the MOS tube Q1, so that the MOS tube Q1 outputs the modulated power to the linear adjustment module;

[0072] Step S40, the MCU sends the loading voltage Vset and the loading current Iset to the linear modulation module through the digital-to-analog converter, and the linear modulation module linearly adjusts the input power supply based on the received loading voltage Vset and the loading current Iset, so that the input voltage and current reach the required value and accuracy;

[0073] Step S50, the detection module detects the input current Isensor of the linear adjustment module, the linear voltage difference Vmos of the MOS tube Q2, the output voltage Vout of the linear adjustment module, the temperature Tmos at both ends of the MOS tube Q2, and the bus voltage Vbus output by the switch adjustment circuit;

[0074] Step S60, the MCU calculates the power loss Pmos of the MOS tube Q2 based on the input current Isensor, the linear voltage difference Vmos, the output voltage Vout and the bus voltage Vbus, and adjusts the pulse width modulation signal of the MOS tube Q1 based on the power loss Pmos, the MOS tube power lower limit and the MOS tube power upper limit; the bus voltage Vbusset is the set value of the bus voltage, the bus voltage Vbus is the actual measured value of the bus voltage, and the initial state of Vbusset is full-scale output, in order to shorten the time of the voltage and current rising edge;

[0075] In step S70 , the MCU performs safety monitoring on the temperature Tmos, the output voltage Vout and the input current Isensor based on the temperature threshold, the voltage threshold and the current threshold.

[0076] In step S30, the calculation formula of the bus voltage is:

[0077] Vbusset = voltage drop of MOS tube Q2 + Vmax.

[0078] For example, if the voltage drop of MOS tube Q2 is 3V and the maximum output voltage of the battery to be tested is 15V, the bus voltage Vbusset is 18V.

[0079] The step S60 specifically includes:

[0080] Step S61: The MCU calculates the power loss Pmos of the MOS tube Q2 based on the hardware multiplier using the input current Isensor and the linear voltage difference Vmos:

[0081] Pmos = Vmos * Isensor;

[0082] Alternatively, the power loss Pmos of the MOS tube Q2 is calculated using the input current Isensor, the output voltage Vout and the bus voltage Vbus:

[0083] Pmos = (Vout - Vbus) * Isensor;

[0084] MCU can calculate Pmos by itself, or directly obtain the calculation result of Pmos through the hardware multiplier;

[0085] Step S62, MCU determines whether the power loss Pmos is less than the lower limit of the MOS tube power. If so, the duty cycle of the pulse width modulation signal of the MOS tube Q1 is increased; if not, the process proceeds to step S63;

[0086] Step S63, the MCU determines whether the power loss Pmos is greater than the upper limit of the MOS tube power. If so, the duty cycle of the pulse width modulation signal of the MOS tube Q1 is reduced; if not, the process proceeds to step S70.

[0087] The step S70 is specifically as follows:

[0088] The MCU determines whether the temperature Tmos is greater than the temperature threshold, whether the output voltage Vout is greater than the voltage threshold, or whether the input current Isensor is greater than the current threshold. If so, the output of the switching linear composite power supply is turned off; if not, monitoring continues.

[0089] In summary, the advantages of the present invention are:

[0090] 1. By setting a detection module including a current detection circuit, a linear voltage difference detection circuit, an output voltage detection circuit, a temperature detection circuit and a bus voltage detection circuit, the detection module is used to detect the input current Isensor of the linear adjustment module, the linear voltage difference Vmos of the MOS tube Q2, the output voltage Vout of the linear adjustment module, the temperature Tmos at both ends of the MOS tube Q2 and the bus voltage Vbus output by the switch adjustment circuit in real time, so that the MCU can adjust the duty cycle of the pulse width modulation signal of the MOS tube Q1 in real time based on the detected data, that is, adjust the bus voltage Vbusset to reduce power loss, thereby greatly improving the working efficiency of the power supply and greatly improving the thermal stability of the power supply.

[0091] 2. By setting a digital-to-analog converter, the loading voltage Vset and loading current Iset received by the MCU are transmitted to the linear adjustment module, and then the output of the linear adjustment module is accurately controlled, which greatly improves the output accuracy of the power supply.

[0092] 3. The bus voltage Vbusset is calculated through the voltage drop of the MOS tube Q2 and the maximum output voltage Vmax of the battery to be tested, and then the output of the MOS tube Q1 is set based on the calculated bus voltage Vbusset to achieve dynamic adjustment of the bus voltage, thereby greatly improving the application range of the power supply, that is, adaptability.

[0093] 4. The MCU monitors the temperature Tmos, output voltage Vout and input current Isensor based on the temperature threshold, voltage threshold and current threshold respectively. When the threshold is exceeded, the output of the switching linear composite power supply is immediately shut down, thereby greatly improving safety.

[0094] Although the specific implementation modes of the present invention are described above, those skilled in the art should understand that the specific implementation modes described are only illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A control method for a switching linear composite power supply, characterized in that: The method requires the use of a switching linear composite power supply as follows, including a control module, a DC-DC power module, a linear adjustment module and a detection module; The output end of the DC-DC power supply module is connected to the input end of the linear adjustment module; the input end of the detection module is connected to the DC-DC power supply module and the linear adjustment module, and the output end is connected to the control module; the control module is connected to the DC-DC power supply module and the linear adjustment module; The control module includes an MCU, a hardware multiplier, a digital-to-analog converter and a communication interface group; One end of the hardware multiplier is connected to the MCU, and the other end is connected to the detection module; one end of the digital-to-analog converter is connected to the MCU, and the other end is connected to the linear adjustment module; the MCU is connected to the communication interface group and the detection module respectively; The communication interface group includes an SPI interface, a UART interface, an IIC interface and an Ethernet interface; The DC-DC power supply module includes a filter circuit and a switch adjustment circuit; The switch adjustment circuit is respectively connected to the filter circuit, the linear adjustment module, the control module and the detection module; The filter circuit includes a capacitor C1, a capacitor C2, an inductor L1 and an inductor L2; One end of the inductor L1 is connected to the capacitor C1, and the other end is connected to the capacitor C2 and the switch adjustment circuit; one end of the inductor L2 is connected to the capacitor C1, and the other end is connected to the capacitor C2 and the switch adjustment circuit; The switch adjustment circuit includes a capacitor C3, a capacitor C4, a diode D1, an inductor L3 and a MOS tube Q1; The D pole of the MOS tube Q1 is connected to the capacitor C3, the capacitor C2 and the inductor L1, the S pole is connected to the inductor L3 and the output end of the diode D1, and the G pole is connected to the control module; one end of the capacitor C4 is connected to the inductor L3 and the linear adjustment module, and the other end is connected to the input end of the diode D1, the capacitor C3, the capacitor C2, the inductor L2 and the linear adjustment module; The linear adjustment module includes a capacitor C5, a capacitor C6 and a MOS tube Q2; The D pole of the MOS tube Q2 is connected to the capacitor C5, the DC-DC power module and the detection module, the S pole is connected to the capacitor C6 and the detection module, and the G pole is connected to the control module; the capacitor C5 is connected to the capacitor C6 and the DC-DC power module; The detection module includes a current detection circuit, a linear voltage difference detection circuit, an output voltage detection circuit, a temperature detection circuit and a bus voltage detection circuit; The input end of the current detection circuit is connected to the output end of the DC-DC power supply module, and the output end is connected to the control module; the input end of the linear voltage difference detection circuit is connected to the input end and the output end of the linear adjustment module, and the output end is connected to the control module; the input end of the output voltage detection circuit is connected to the output end of the linear adjustment module, and the output end is connected to the control module; the input end of the temperature detection circuit is connected to the linear adjustment module, and the output end is connected to the control module; the input end of the bus voltage detection circuit is connected to the output end of the DC-DC power supply module, and the output end is connected to the control module; The method comprises the following steps: Step S10, MCU receives power supply parameters sent by the host computer through the communication interface group; the power supply parameters include loading voltage Vset, loading current Iset, MOS tube Q2 voltage drop, maximum output voltage Vmax of the battery to be tested, MOS tube power lower limit, MOS tube power upper limit, temperature threshold, voltage threshold and current threshold; Step S20, the filter circuit filters the DC voltage regulator and then inputs the filtered DC voltage regulator into the switch adjustment circuit; Step S30, the MCU calculates the bus voltage Vbusset based on the voltage drop of the MOS tube Q2 and the maximum output voltage Vmax of the battery to be tested, and outputs a corresponding pulse width modulation signal to the MOS tube Q1 based on the bus voltage Vbusset, so that the MOS tube Q1 outputs the modulated power to the linear adjustment module; Step S40: The MCU sends the loading voltage Vset and the loading current Iset to the linear modulation module through the digital-to-analog converter, and the linear modulation module linearly adjusts the input power supply based on the received loading voltage Vset and the loading current Iset; Step S50, the detection module detects the input current Isensor of the linear adjustment module, the linear voltage difference Vmos of the MOS tube Q2, the output voltage Vout of the linear adjustment module, the temperature Tmos at both ends of the MOS tube Q2, and the bus voltage Vbus output by the switch adjustment circuit; Step S60, the MCU calculates the power loss Pmos of the MOS tube Q2 based on the input current Isensor, the linear voltage difference Vmos, the output voltage Vout and the bus voltage Vbus, and adjusts the pulse width modulation signal of the MOS tube Q1 based on the power loss Pmos, the MOS tube power lower limit and the MOS tube power upper limit; In step S70 , the MCU performs safety monitoring on the temperature Tmos, the output voltage Vout and the input current Isensor based on the temperature threshold, the voltage threshold and the current threshold.

2. The control method of a switching linear composite power supply according to claim 1, characterized in that: In step S30, the calculation formula of the bus voltage is: Vbusset = voltage drop of MOS tube Q2 + Vmax.

3. The control method of a switching linear composite power supply according to claim 1, characterized in that: The step S60 specifically includes: Step S61: The MCU calculates the power loss Pmos of the MOS tube Q2 based on the hardware multiplier using the input current Isensor and the linear voltage difference Vmos: Pmos = Vmos * Isensor; Alternatively, the power loss Pmos of the MOS tube Q2 is calculated using the input current Isensor, the output voltage Vout and the bus voltage Vbus: Pmos = (Vout - Vbus) * Isensor; Step S62, MCU determines whether the power loss Pmos is less than the lower limit of the MOS tube power. If so, the duty cycle of the pulse width modulation signal of the MOS tube Q1 is increased; if not, the process proceeds to step S63; Step S63, the MCU determines whether the power loss Pmos is greater than the upper limit of the MOS tube power. If so, the duty cycle of the pulse width modulation signal of the MOS tube Q1 is reduced; if not, the process proceeds to step S70.

4. The control method of a switching linear composite power supply according to claim 1, characterized in that: The step S70 is specifically as follows: The MCU determines whether the temperature Tmos is greater than the temperature threshold, whether the output voltage Vout is greater than the voltage threshold, or whether the input current Isensor is greater than the current threshold. If so, the output of the switching linear composite power supply is turned off; if not, monitoring continues.

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