Programmable direct current electronic load based on multi-mode compatible topology and regulation and control method

Abstract

The invention discloses a programmable DC electronic load based on a multi-mode compatible topology and a regulation and control method. In the electronic load, a subtracter, a DAC multiplier, a PGA, an analog adder, a current feedback comparator, a main DSP controller, a DAC1 and a DAC2 form the multi-mode compatible topology; in the multi-mode compatible topology, a main DSP controller is used for respectively controlling a DAC1, a DAC2, a DAC multiplier and a PGA by setting four parameters of DVset, DIset, DRset and DPGA, so that an electronic load works in a specific mode or performs mode switching, and accurate testing of a tested power supply is realized; in a multi-mode compatible topology, a tested power supply is tested in four modes of CC, CR, CV and LED, and the four modes of CC, CR, CV and LED are continuously switched in any two modes without interruption.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power automation, and in particular to a programmable direct current electronic load based on a multi-mode compatible topology and a control method thereof. Background Art

[0002] Various power supplies such as switching power supplies, chargers, generators, LED power supplies, etc., all need to be tested for output characteristics. The traditional test method is to use resistors as loads, but resistors are difficult to control quickly and accurately, and it is difficult to meet the requirements of production automation. Electronic loads are a technical solution to this problem.

[0003] The electronic load is based on the negative feedback control technology of MOS-FET. According to the feedback of electrical signals such as voltage and current, the electronic load adjusts the G pole voltage of MOS-FET, and then adjusts the current between the D pole and S pole of MOS-FET, realizing precise control of various load modes such as CC, CR, CP, CV, LED, etc.

[0004] Traditional electronic loads usually have a single negative feedback mode. The switching of different load modes is either based on software simulation or hardware switching of different feedback loops. The former has considerable limitations in terms of control accuracy and bandwidth. The latter's feedback loop hardware switching will produce an interruption process, which is limited in many detection applications, especially in the detection applications of programmable power supplies and digital power supplies. This interruption process limits the scope of detection applications. In addition, in traditional electronic loads, the CV mode is usually prone to oscillation because the feedback depth cannot be adjusted; the CR mode is usually based on the software servo of the input voltage based on the current feedback loop, which is prone to oscillation; the LED mode is usually based on the software servo of the input voltage based on the current feedback loop, which is difficult to adapt to the test requirements of LEDs in dimming mode. Summary of the invention

[0005] Technical purpose: In view of the defects in the prior art, the present invention discloses a programmable DC electronic load and a control method based on a multi-mode compatible topology, which realizes testing of the power supply under test in four modes of CC, CR, CV, and LED in a multi-mode compatible topology, and continuous and uninterrupted switching between any two of the four modes.

[0006] Technical solution: In order to achieve the above technical objectives, the present invention adopts the following technical solution.

[0007] A programmable DC electronic load based on a multi-mode compatible topology comprises: a main DSP controller, DAC1, DAC2, MOS-FET and its driving module, a current signal conditioning circuit, a current feedback comparator, a sampling resistor, a voltage signal conditioning circuit, a subtractor, a DAC multiplier, a PGA, and an analog adder; the power supply under test is respectively connected to the MOS-FET and its driving module, the sampling resistor, and the voltage signal conditioning circuit, the voltage signal conditioning circuit is connected to DAC1 through the subtractor, the subtractor, the DAC multiplier, the PGA, the analog adder, and the current feedback comparator are connected in sequence, the sampling resistor is connected to the current feedback comparator through the current signal conditioning circuit, the main DSP controller is respectively connected to the MOS-FET and its driving module , DAC1, DAC2, DAC multiplier, PGA are connected, and the subtractor, DAC multiplier, PGA, analog adder, current feedback comparator, main DSP controller, DAC1, and DAC2 constitute a multi-mode compatible topology; in the multi-mode compatible topology, the main DSP controller is used to control DAC1, DAC2, DAC multiplier, and PGA respectively through the setting of four parameters D_Vset, D_Iset, D_Rset, and D_PGA, so that the electronic load works in a specific mode or performs mode switching, so as to achieve accurate testing of the power supply under test; the specific mode is one of the four modes of CC, CR, CV, and LED, and the mode switching is switching between any two of the four modes of CC, CR, CV, and LED.

[0008] Preferably, in the main DSP controller, D_Vset is input to DAC1, DAC1 is used to perform digital-to-analog conversion on D_Vset, and output a voltage reference value Vset to a subtractor; the positive input signal of the subtractor is the fifth voltage Vf, and the negative input signal is the voltage reference value Vset, the voltage reference value Vset is subtracted from the fifth voltage Vf as the output signal, and is fed back to the DAC multiplier; the fifth voltage Vf is the output signal of the voltage signal conditioning circuit, the voltage signal conditioning circuit is used to collect the voltage Vin of the power supply under test, the voltage Vin of the power supply under test is amplified by the voltage signal conditioning circuit and outputs the fifth voltage Vf; D_Rset is input to the DAC multiplier, the DAC multiplier is used to perform multiplication-type digital-to-analog conversion and proportional amplification on two inputs, namely D_Rset and the output signal of the subtractor, and output the first voltage V1 to PGA; D_PGA is input to the PGA, the PGA is used to perform multiplication-type digital-to-analog conversion and gain amplification on two inputs, namely D_PGA and the first voltage V1, and output Output the second voltage V2 to the analog adder; D_Iset is input to DAC2, DAC2 is used to perform digital-to-analog conversion on D_Iset, and output the current reference value Iset to the analog adder; the analog adder is used to output the third voltage V3 after superimposing the two inputs, namely the current reference value Iset and the second voltage V2, and feedback it to the current feedback comparator as the positive input signal of the current feedback comparator, and the negative input signal of the current feedback comparator is the output signal of the current signal conditioning circuit, namely the first current If; the sampling resistor is used to collect the current of the power supply under test, and output the current signal Iout of the power supply under test to the current signal conditioning circuit, the current signal conditioning circuit is used to amplify the current signal Iout of the power supply under test, and output the first current If; the current feedback comparator is used to compare and output the two inputs, namely the first current If and the third voltage V3, and the output signal is a fourth voltage signal V4, and the fourth voltage signal V4 is used to drive the MOS-FET and its driving module, thereby controlling the power supply under test.

[0009] Preferably, it also includes a human-machine interface and a host computer software. The external mode instruction received by the main DSP controller is obtained from the human-machine interface or the host computer software. The external mode instruction includes the electronic load operating in a specific mode or performing a mode switch.

[0010] A control method for a programmable DC electronic load based on a multi-mode compatible topology is used to control any of the above-mentioned programmable DC electronic loads based on a multi-mode compatible topology. The main DSP controller adjusts a DAC multiplier and a PGA to realize CR load mode control. The main DSP controller adjusts the DAC multiplier, the PGA and DAC1 to realize LED load mode control. The main DSP controller adjusts the DAC multiplier and the PGA gain, and adjusts DAC2 according to the measured current servo to realize CV load mode control with adjustable feedback depth. The main DSP controller adjusts DAC2 to realize CC load mode control, and realizes arbitrary mode switching between the four modes of CC, CR, CV and LED in the multi-mode compatible topology, and the switching process is continuous and uninterrupted.

[0011] Preferably, in CC mode, the main DSP controller sets D_Rset to 0, sets D_PGA to the maximum value, and uses the multi-mode compatible topology as a current negative feedback loop. In a stable state, D_Iset=Iout*K4+B4, wherein Iout is the current signal of the power supply under test, and K4 and B4 are constants. The main DSP controller achieves constant control of the current signal of the power supply under test in CC mode of the electronic load by adjusting the size of D_Iset.

[0012] Preferably, in CV mode, the main DSP controller adjusts D_PGA and D_Rset to the set feedback depth value D_Rset / D_PGA, and the multi-mode compatible topology serves as a voltage negative feedback loop. In a stable state, the servo adjustment realizes D_Iset=Iout*K4+B4, wherein Iout is the current signal of the power supply under test, and K4 and B4 are constants; at this time, D_Vset= K6*Vin+B6, and K6 and B6 are constants; the main DSP controller realizes constant control of the voltage Vin of the power supply under test in the CV mode of the electronic load by adjusting the size of D_Vset.

[0013] Preferably, in CR mode, the main DSP controller sets D_Vset and D_Iset to 0, and the multi-mode compatible topology serves as a resistor negative feedback loop, D_PGA / D_Rset=Vin / Iout*K5+B5, wherein K5 and B5 are constants, and the main DSP controller adjusts the size of D_PGA and D_Rset to control the precise control of the equivalent impedance Vin / Iout of the power supply under test in the CR mode of the electronic load with the value of D_PGA / D_Rset.

[0014] Preferably, in LED mode, it is equivalent to the series connection of a constant voltage source VF and an equivalent series resistor Rd. The main DSP controller sets D_Iset to 0, and the multi-mode compatible topology serves as the LED negative feedback loop. At this time, Iout = D_Rset / D_PGA*(D_Vset / 65535*Vref –(K1*Vin+B1)); the main DSP controller adjusts the size of D_Vset, D_PGA, and D_Rset to make D_Vset = K6*VF+B6; and makes D_PGA / D_Rset = Rd*K5+B5; wherein K1, B1, B5, K5, K6, and B6 are constants, and Vref is a constant; to achieve precise control of the start-up voltage VF and the equivalent series resistor Rd in the LED mode of the electronic load.

[0015] Preferably, when switching from CC mode to CV mode, the main DSP controller adjusts D_PGA and D_Rset to set feedback depth values, then adjusts D_Vset to a set voltage, and finally uses the measured value of the electronic load current to serve D_Iset to achieve switching; when switching from CC mode to CR mode, the main DSP controller first adjusts D_Vset to 0, then adjusts D_Iset to 0, and finally adjusts D_PGA and D_Rset to a set resistance value; when switching from CC mode to LED mode, the main DSP controller adjusts D_Vset to a set VF value, then adjusts D_Iset to 0, and finally adjusts D_PGA and D_Rset to a set resistance Rd value; When switching from CV mode to CC mode, the main DSP controller adjusts D_Rset to 0, adjusts D_PGA to 65535, and then adjusts D_Iset to the set current value; when switching from CV mode to CR mode, the main DSP controller adjusts D_PGA and D_Rset to the set resistance value, and then adjusts D_Vset to 0; when switching from CV mode to LED mode, the main DSP controller adjusts D_PGA and D_Rset to the set Rd value, and then adjusts D_Iset to 0, and finally adjusts D_Vset to the set VF value; When switching from CR mode to CC mode, the main DSP controller adjusts D_Rset to 0, adjusts D_PGA to 65535, and then adjusts D_Iset to the set current value; when switching from CR mode to CV mode, the main DSP controller adjusts D_Vset to the set voltage value, and then adjusts D_Rset and D_PGA to the set feedback depth value, and finally uses the measured value of the electronic load current to servo D_Iset; when switching from CR mode to LED mode, the main DSP controller adjusts D_Vset to the set VF value, and then adjusts D_Rset and D_PGA to the set Rd value; When switching from LED mode to CC mode, the main DSP controller adjusts D_Rset to 0, adjusts D_PGA to 65535, and then adjusts D_Iset to the set current value; when switching from LED mode to CV mode, the main DSP controller adjusts D_Rset and D_PGA to the set feedback depth, and then adjusts D_Vset to the set voltage value, and finally servo D_Iset with the measured value of the electronic load current; when switching from LED mode to CR mode, the main DSP controller adjusts D_Rset and D_PGA to the set resistance values, and then adjusts D_Vset to 0.

[0016] Beneficial effects: 1. The present invention implements a multi-mode compatible topology to test the power supply under test in four modes: CC, CR, CV, and LED. The four modes can be switched between any two of them continuously without interruption, thus avoiding the interruption in the switching process of different modes of ordinary electronic loads. 2. The present invention realizes CR mode and LED mode through hardware multi-mode compatible topology, and the control accuracy and universality are better than ordinary electronic loads that use software servo CR and LED modes; 3. The CV mode with feedback depth control in the present invention is more universal than the CV mode with fixed feedback depth or the common electronic load of CV with multiple feedback depth adjustments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a structural diagram of an electronic load according to an embodiment of the present invention; Figure 2 This is a VI schematic diagram under CC mode of an embodiment of the present invention; Figure 3 This is a schematic diagram of VI in the CV mode of an embodiment of the present invention; Figure 4 This is a schematic diagram of VI in the CR mode of an embodiment of the present invention; Figure 5 This is a VI schematic diagram of an LED mode according to an embodiment of the present invention; Figure 6 The figure is a schematic diagram of signal flow according to an embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0019] It should be noted that the terms used herein are only for describing specific implementation methods, and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the unit form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or their combinations.

[0020] As attached Figure 1 As shown, a programmable DC electronic load based on a multi-mode compatible topology of this embodiment includes: a main DSP controller, DAC1, DAC2, MOS-FET and its driving module, a current signal conditioning circuit, a current feedback comparator, a sampling resistor, a voltage signal conditioning circuit, a subtractor, a DAC multiplier, a PGA (Programmable gain amplifier), and an analog adder; the power supply under test is respectively connected to the MOS-FET and its driving module, the sampling resistor, and the voltage signal conditioning circuit, the voltage signal conditioning circuit is connected to DAC1 through the subtractor, the subtractor, the DAC multiplier, the PGA, the analog adder, and the current feedback comparator are connected in sequence, the sampling resistor is connected to the current feedback comparator through the current signal conditioning circuit, the main DSP controller is respectively connected to the MOS-FET and its driving module, DAC1, DAC2, the DAC multiplier, and the PGA, the subtractor, the DAC multiplier, the PGA, the analog adder The electronic load comprises a current feedback comparator, a main DSP controller, DAC1 and DAC2, which constitute a multi-mode compatible topology; in the multi-mode compatible topology, the main DSP controller is used to control DAC1, DAC2, DAC multiplier and PGA respectively through the setting of four parameters D_Vset, D_Iset, D_Rset and D_PGA, so that the electronic load works in a specific mode or performs mode switching, so as to realize accurate testing of the power supply under test; the specific mode is one of the four modes of CC, CR, CV and LED, and the mode switching is switching between any two of the four modes of CC, CR, CV and LED.

[0021] The main DSP controller is connected to the human-machine interface and the host computer software. The external mode command received by the main DSP controller is obtained from the human-machine interface or the host computer software. The main DSP controller sets four parameters, D_Vset, D_Iset, D_Rset, and D_PGA, to match the feedback loop topology corresponding to the preset working mode, and sets related parameters to achieve the regulation and precision control of the electronic load. The main DSP controller is implemented using existing modules and will not be described in detail here.

[0022] The main DSP controller is connected to the host computer software through the RS232 communication interface and the SCPI protocol, receives the instructions of the host computer software, realizes the various working modes of the electronic load and the loading of the specified parameters, and feeds back the measured electrical parameters and working status to the host computer software, thereby realizing the remote control and electrical parameter monitoring of the electronic load, as well as the linkage between the electronic load and other instruments, thereby realizing the automatic detection of the power supply under test. To this end, a programmable DC electronic load based on a multi-mode compatible topology in this embodiment also includes an electrical parameter measurement unit, which is used to obtain the electrical parameters of the power supply under test through the main DSP controller, and its connection relationship is as follows: Figure 1 Not shown.

[0023] As attached Figure 6 As shown, in the main DSP controller, D_Vset is input to DAC1, DAC1 is used to perform digital-to-analog conversion on D_Vset, and output a voltage reference value Vset to a subtractor; the positive input signal of the subtractor is the fifth voltage Vf, and the negative input signal is the voltage reference value Vset. The voltage reference value Vset is subtracted from the fifth voltage Vf as the output signal, and is fed back to the DAC multiplier; the fifth voltage Vf is the output signal of the voltage signal conditioning circuit, and the voltage signal conditioning circuit is used to collect the voltage Vin of the power supply under test, and the voltage Vin of the power supply under test is amplified by the voltage signal conditioning circuit to output the fifth voltage Vf; D_Rset is input to the DAC multiplier, and the DAC multiplier is used to perform multiplication-type digital-to-analog conversion and proportional amplification on two inputs, namely D_Rset and the output signal of the subtractor, and output the first voltage V1 to PGA; D_PGA is input to PGA, and PGA is used to perform multiplication-type digital-to-analog conversion and gain amplification on two inputs, namely D_PGA and the first voltage V1. amplify, and output the second voltage V2 to the analog adder; D_Iset is input to DAC2, DAC2 is used to perform digital-to-analog conversion on D_Iset, and output the current reference value Iset to the analog adder; the analog adder is used to output the third voltage V3 after superimposing the two inputs, namely the current reference value Iset and the second voltage V2, and feedback it to the current feedback comparator as the positive input signal of the current feedback comparator, and the negative input signal of the current feedback comparator is the output signal of the current signal conditioning circuit, namely the first current If; the sampling resistor is used to collect the current of the power supply under test, and output the current signal Iout to the current signal conditioning circuit, and the current signal conditioning circuit is used to amplify the current signal Iout and output the first current If; the current feedback comparator is used to compare and output the two inputs, namely the first current If and the third voltage V3, and the output signal is the fourth voltage signal V4, and the fourth voltage signal V4 is used to drive the MOS-FET and its driving module, thereby controlling the power supply under test; The voltage signal conditioning circuit is used to collect the voltage Vin of the power supply under test. The voltage Vin of the power supply under test is amplified by the voltage signal conditioning circuit and then output as the fifth voltage Vf. The fifth voltage Vf is sent to the ADC converter of the electrical parameter measurement unit to complete the precise detection of the voltage and is used for servo applications of various algorithms. At the same time, the fifth voltage Vf also participates in the feedback as the positive input of the subtractor and is enabled in the CR mode, CV mode and LED mode. The output of DAC1 participates in the feedback as the negative input of the subtractor and is enabled in the CR mode, CV mode and LED mode. As shown in the attached figure Figure 2 -Attached Figure 5 As shown, the VI schematic diagrams in four modes of CC, CV, CR and LED are given. The present invention is implemented in a multi-mode compatible topology, and the four modes of CC, CR, CV and LED are implemented to test the power supply under test, and the four modes of CC, CR, CV and LED are switched continuously without interruption when any two of them are switched; the interruption in the switching process of different modes of ordinary electronic loads is avoided.

[0024] The sampling resistor is used to collect the current of the power supply under test, and output the current signal Iout to the current signal conditioning circuit. The current signal conditioning circuit is used to amplify the current signal Iout and output the first current If. The first current If is sent to the ADC converter of the electrical parameter measurement unit to complete the precise detection of the current and is used for servo applications of various algorithms. At the same time, the first current If is also used as the negative input of the current feedback comparator, and the output of the analog adder, that is, the third voltage V3, is used as the positive input of the current feedback comparator. The output of the current feedback comparator, that is, the fourth voltage V4, is used to drive the MOS-FET and its driving module. The power supply under test, the sampling resistor, the current signal conditioning current, the analog adder, the current feedback comparator, the MOS-FET and its driving module constitute a current negative feedback loop in a multi-mode compatible topology. In the stable state of negative feedback of the current negative feedback loop, the output of the current signal conditioning circuit, that is, the first current If, is highly close to the output of the analog adder, that is, the third voltage V3.

[0025] The core component of the DAC multiplier is a multiplication type DAC converter. The output of the subtractor is used as the analog input of the DAC multiplier. The main DSP controller controls the ratio of its output V1 to the analog input by adjusting D_Rset. The DAC multiplier makes a reverse output, V1=D_Rset / 65535*(Vf- Vset). The DAC multiplier is enabled in CR, CV and LED modes. The DAC multiplier is implemented using existing modules and will not be described in detail here.

[0026] The core components of PGA are a precision operational amplifier and a 16-bit multiplying DAC converter. The precision operational amplifier is used in the topology of in-phase amplification, but the multiplying DAC converter replaces the two resistors in the same amplification circuit to control the gain. The gain of PGA is G=65535 / D_PGA. PGA is enabled in CR, CV and LED modes. PGA is implemented using existing modules and will not be described in detail here.

[0027] The analog adder is a two-channel analog adder, and the output of the analog adder: V3=V2+Iset, is used as the positive input of the current feedback comparator, and acts on a current negative feedback. The analog adder is implemented using existing modules and will not be described in detail here.

[0028] MOS-FET and its driving module are composed of multiple groups of MOS-FET and their current sharing control circuits connected in parallel. MOS-FET works in the linear region, converts the electrical energy of the power supply under test into thermal energy, and is installed on an aluminum heat sink. The hot air is discharged by forced air cooling. The load current of MOS-FET and its driving module presents a linear relationship with the output voltage of the current feedback comparator, and under the negative feedback of the feedback loop, precise control of different working modes is achieved. MOS-FET and its driving module are implemented using existing modules, which will not be described in detail here.

[0029] In the present invention, the four control modes of the electronic load, CC, CR, CV, and LED, are implemented in the same hardware feedback loop, i.e., a multi-mode compatible topology. No hardware switching is required when switching modes. In the same hardware feedback loop, the main DSP controller can simultaneously adjust up to 4 DAC converters, which are respectively used for precise control of CV voltage / LED turn-on voltage, CC current, CR equivalent resistance / LED equivalent series connection, and CV feedback depth, and complete seamless switching of different working modes.

[0030] The topological structure disclosed in the present invention can realize negative feedback of two signals, voltage and current, in the same feedback loop, and can simultaneously control four parameters, voltage, current, equivalent series resistance, and feedback depth, through a main DSP controller.

[0031] A control method for a programmable DC electronic load based on a multi-mode compatible topology, the method comprising: The main DSP controller adjusts the DAC multiplier and PGA to achieve CR load mode control. The main DSP controller adjusts the DAC multiplier, PGA and DAC1 to achieve LED load mode control. The main DSP controller adjusts the DAC multiplier and PGA gain, and adjusts DAC2 according to the measured current servo to achieve CV load mode control with adjustable feedback depth. The main DSP controller adjusts DAC2 to achieve CC load mode control.

[0032] Wherein, Vset=(D_Vset / 65535)*Vref; D_Vset∈[0,65535]; Vref is a constant used to provide a 2.5V voltage reference for DAC1 and DAC2; Iset =(D_Iset / 65535)*Vref; D_Iset∈[0,65535]; Vf=K1*Vin+B1; K1, B1 are constants obtained through the conventional calibration process; Iout=K2*If+B2; K2, B2 are constants obtained through the conventional calibration process; V1 =D_Rset / 65535*( Vf- Vset )ci; D_Rset∈[0,65535]; V2= V2=65535 / D_PGA*V1 =D_Rset / D_PGA*(Vset-Vf); D_PGA∈[1,65535]; V3 =Iset+V2; Iout=K3*V4+B3; K3, B3 are constants; When the system forms a stable negative feedback: If=V3; In CC mode, the main DSP controller sets D_Rset to 0 and D_PGA to the maximum value, such as 65535. The multi-mode compatible topology acts as a current negative feedback loop. Since D_Rset is set to 0, the output first voltage V1 of the DAC multiplier is 0, and the output of the PGA is 0; at this time, the output third voltage V3 of the analog adder is equal to the reference current Iset output by DAC2. When the current signal Iout of the power supply under test increases, the output first current If of the current signal conditioning circuit increases synchronously. At this time, the output fourth voltage V4 of the current feedback comparator will decrease, and the driving voltage of the MOS-FET and its driving module will decrease, thereby controlling the power supply under test, and the current of the power supply under test collected by the sampling resistor is reduced, forcing the current signal Iout of the power supply under test to decrease and return, thereby forming current negative feedback and realizing CC mode.

[0033] When the negative feedback works stably, D_Iset=Iout*K4+B4; wherein K4 and B4 are constants obtained through the calibration process. At this time, the main DSP controller achieves precise control of the electronic load CC mode load current Iout by adjusting the size of D_Iset.

[0034] When the electronic load works in CV mode, the main DSP controller adjusts D_PGA and D_Rset to the set feedback depth value D_Rset / D_PGA, and the multi-mode compatible topology is used as a voltage negative feedback loop. D_Vset is the set voltage in CV mode, and D_Rset / D_PGA is the set feedback depth in CV mode. D_Iset requires the real-time measurement value of the servo load current Iout.

[0035] When the input voltage Vin of the electronic load increases, the output of the subtractor, the output second voltage V2 of the PGA, and the output third voltage V3 of the analog adder also increase synchronously. At this time, the output fourth voltage V4 of the current feedback comparator will also increase synchronously, and then the driving voltage of the MOS-FET and its driving module will be reduced, thereby controlling the power supply under test, and the current of the power supply under test collected by the sampling resistor, thereby forcing the load current of the electronic load, that is, the current signal Iout of the power supply under test to increase synchronously, thereby forcing the input voltage Vin of the electronic load to decrease and return, forming a negative feedback.

[0036] When the negative feedback is working stably, D_Vset= K6*Vin+B6+K7*(Iout-(D_Iset / 65535*Vref*K2+B2))*D_PGA / D_Rset, where K6, B6, K7, K2, and B2 are constants respectively, which are obtained through the conventional calibration process; in this embodiment, all K and B are constants obtained during the calibration process. At this time, the main DSP controller continuously servo-adjusts D_Iset according to the collected current signal Iout value of the measured power supply, so that D_Iset= Iout*K4+B4, so that Iout=D_Iset / 65535*Vref*K2+B2; at this time D_Vset= K6*Vin+B6. At this time, the main DSP controller achieves precise control of the input voltage Vin of the electronic load in CV mode by adjusting the size of D_Vset. At the same time, the main DSP controller also controls the feedback depth in CV mode by adjusting the size of D_PGA and D_Rset with the value of D_PGA / D_Rset. The CV mode with feedback depth control in the present invention has better universality than the CV mode with fixed feedback depth or the common electronic load of CV with multiple feedback depth adjustments.

[0037] When the electronic load works in CR mode, the main DSP controller first sets D_Vset of DAC1 to 0 and D_Iset of DAC2 to 0, and the multi-mode compatible topology serves as a resistor negative feedback loop; at this time, the output reference current Iset of DAC2 is 0, V3=V2; D_PGA / D_Rset=Vin / Iout*K5+B5, where K5 and B5 are constants obtained through the calibration process. The main DSP controller controls the electronic load CR mode equivalent impedance Vin / Iout precisely by adjusting the size of D_PGA and D_Rset with the value of D_PGA / D_Rset.

[0038] When the electronic load works in LED mode, it is equivalent to a constant voltage source VF and an equivalent series resistor Rd in series. When the electronic load works in LED mode, the main DSP controller first sets D_Iset of DAC2 to 0, and the multi-mode compatible topology serves as the LED negative feedback loop. At this time, Iout= D_Rset / D_PGA*(D_Vset / 65535*Vref –(K1*Vin+B1)); wherein K1 and B1 are constants respectively; at this time, the main DSP controller adjusts the size of D_Vset, D_PGA, and D_Rset to set D_Vset= K6*VF+B6; sets D_PGA / D_Rset=Rd*K5+B5, where K6, B6, K5+, and B5 are all constants obtained by calibration; by controlling D_Vset and D_PGA, precise control of the start-up voltage VF and the equivalent series resistor Rd in the LED mode of the electronic load is achieved.

[0039] LED mode can also be used to simulate batteries. In this case, the constant voltage source VF is equivalent to the open circuit voltage of the battery, and the equivalent series resistance Rd is equivalent to the internal resistance of the battery. The adjustment method is the same as described above.

[0040] When the electronic load needs to switch from CC mode to CV mode, the main DSP controller adjusts D_PGA and D_Rset to the set feedback depth value, then adjusts D_Vset to the set voltage, and finally servo D_Iset with the measured value of the electronic load pull current to achieve switching. The whole process is continuous and uninterrupted. Among them, the feedback depth value is a preset value and can be set through the human-machine interface. The feedback depth value corresponds to D_Rset / D_PGA and is presented in terms of resistance. The larger the resistance, the shallower the feedback depth, and the smaller the resistance, the deeper the feedback depth.

[0041] When the electronic load needs to switch from CC mode to CR mode, the main DSP controller first adjusts D_Vset to 0, then adjusts D_Iset to 0, and finally adjusts D_PGA and D_Rset to the set resistance Rd value. The whole process is continuous and uninterrupted.

[0042] When the electronic load needs to switch from CC mode to LED mode, the main DSP controller adjusts D_Vset to the set VF value, then adjusts D_Iset to 0, and finally adjusts D_PGA and D_Rset to the set resistance Rd value. The whole process is continuous and uninterrupted.

[0043] When the electronic load needs to switch from CV mode to CC mode, the main DSP controller adjusts D_Rset to 0, adjusts D_PGA to 65535, and then adjusts D_Iset to the set current value. The whole process is continuous and uninterrupted.

[0044] When the electronic load needs to switch from CV mode to CR mode, the main DSP controller adjusts D_PGA and D_Rset to the set resistance values, and then adjusts D_Vset to 0. The whole process is continuous and uninterrupted.

[0045] When the electronic load needs to switch from CV mode to LED mode, the main DSP controller adjusts D_PGA and D_Rset to the set Rd value, then adjusts D_Iset to 0, and finally adjusts D_Vset to the set VF value. The whole process is continuous and uninterrupted.

[0046] When the electronic load needs to switch from CR mode to CC mode, the main DSP controller adjusts D_Rset to 0, adjusts D_PGA to 65535, and then adjusts D_Iset to the set current value. The whole process is continuous and uninterrupted.

[0047] When the electronic load needs to switch from CR mode to CV mode, the main DSP controller adjusts D_Vset to the set voltage value, then adjusts D_Rset and D_PGA to the set feedback depth value, and finally uses the measured value of the electronic load pull current to serve D_Iset. The whole process is continuous and uninterrupted.

[0048] When the electronic load needs to switch from CR mode to LED mode, the main DSP controller adjusts D_Vset to the set VF value, and then adjusts D_Rset and D_PGA to the set Rd values. The whole process is continuous and uninterrupted.

[0049] When the electronic load needs to switch from LED mode to CC mode, the main DSP controller adjusts D_Rset to 0, adjusts D_PGA to 65535, and then adjusts D_Iset to the set current value. The whole process is continuous and uninterrupted.

[0050] When the electronic load needs to switch from LED mode to CV mode, the main DSP controller adjusts D_Rset and D_PGA to the set feedback depth, then adjusts D_Vset to the set voltage value, and finally serves D_Iset with the measured value of the electronic load current. The whole process is continuous and uninterrupted.

[0051] When the electronic load needs to switch from LED mode to CR mode, the main DSP controller adjusts D_Rset and D_PGA to the set resistance values, and then adjusts D_Vset to 0. The whole process is continuous and uninterrupted.

[0052] In this embodiment, as shown in the attached Figure 6 As shown, the calculation formulas between variables in different modes include: In CC mode: D_Rset=0; D_PGA=65535; Iout=D_Iset / 65535*Vref*K2+B2; D_Iset=Iout*K4+B4; K4, B4 are constants obtained through the calibration process; In CR mode; D_Vset=0; D_Iset=0; Iout= D_Rset / D_PGA*(K1*Vin+B1); D_PGA / D_Rset=Vin / Iout*K5+B5; K5, B5 are constants obtained through the calibration process; In CV mode: Iout=D_Rset / D_PGA*(D_Vset / 65535*Vref–(K1*Vin+B1))+ D_Iset / 65535*Vref*K2+B2; D_Vset= K6*Vin+B6+K7*(Iout-(D_Iset / 65535*Vref*K2+B2))*D_PGA / D_Rset; When D_Iset=Iout*K4+B4, D_Vset= K6*Vin+B6; K6, B6 are constants obtained through the calibration process; In LED mode: D_Iset=0; Iout= D_Rset / D_PGA*(D_Vset / 65535*Vref –(K1*Vin+B1)); D_Vset= K6*VF+B6; D_PGA / D_Rset=Rd*K5+B5; VF is the LED mode turn-on voltage, and Rd is the LED mode equivalent series resistance.

[0053] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A programmable DC electronic load based on a multi-mode compatible topology, characterized in that: include: The main DSP controller, DAC1, DAC2, MOS-FET and its driving module, current signal conditioning circuit, current feedback comparator, sampling resistor, voltage signal conditioning circuit, subtractor, DAC multiplier, PGA, analog adder; the power supply under test is respectively connected with the MOS-FET and its driving module, sampling resistor, voltage signal conditioning circuit, the voltage signal conditioning circuit is connected with DAC1 through the subtractor, the subtractor, DAC multiplier, PGA, analog adder, and current feedback comparator are connected in sequence, the sampling resistor is connected with the current feedback comparator through the current signal conditioning circuit, the main DSP controller is respectively connected with the MOS-FET and its driving module, DAC1, DAC2, DA C multiplier, PGA connection, subtractor, DAC multiplier, PGA, analog adder, current feedback comparator, main DSP controller, DAC1, DAC2 constitute a multi-mode compatible topology; in the multi-mode compatible topology, the main DSP controller is used to control DAC1, DAC2, DAC multiplier, PGA respectively through the setting of four parameters D_Vset, D_Iset, D_Rset, and D_PGA, so that the electronic load works in a specific mode or performs mode switching, so as to realize accurate testing of the power supply under test; the specific mode is one of the four modes of CC, CR, CV, and LED, and the mode switching is switching between any two of the four modes of CC, CR, CV, and LED.

2. A programmable DC electronic load based on a multi-mode compatible topology according to claim 1, characterized in that: In the main DSP controller, D_Vset is input to DAC1, DAC1 is used to perform digital-to-analog conversion on D_Vset, and output a voltage reference value Vset to a subtractor; the positive input signal of the subtractor is the fifth voltage Vf, and the negative input signal is the voltage reference value Vset. The voltage reference value Vset is subtracted from the fifth voltage Vf as the output signal, and is fed back to the DAC multiplier; the fifth voltage Vf is the output signal of the voltage signal conditioning circuit, and the voltage signal conditioning circuit is used to collect the voltage Vin of the power supply under test, and the voltage Vin of the power supply under test is amplified by the voltage signal conditioning circuit to output the fifth voltage Vf; D_Rset is input to the DAC multiplier, and the DAC multiplier is used to perform multiplication-type digital-to-analog conversion and proportional amplification on two inputs, namely D_Rset and the output signal of the subtractor, and output the first voltage V1 to PGA; D_PGA is input to the PGA, and the PGA is used to perform multiplication-type digital-to-analog conversion and gain amplification on two inputs, namely D_PGA and the first voltage V1, and output the fifth voltage Vf. The second voltage V2 is input to the analog adder; D_Iset is input to DAC2, DAC2 is used to perform digital-to-analog conversion on D_Iset, and output the current reference value Iset to the analog adder; the analog adder is used to output the third voltage V3 after superimposing the two inputs, namely the current reference value Iset and the second voltage V2, and feedback it to the current feedback comparator as the positive input signal of the current feedback comparator, and the negative input signal of the current feedback comparator is the output signal of the current signal conditioning circuit, namely the first current If; the sampling resistor is used to collect the current of the power supply under test, and output the current signal Iout of the power supply under test to the current signal conditioning circuit, and the current signal conditioning circuit is used to amplify the current signal Iout of the power supply under test and output the first current If; the current feedback comparator is used to compare and output the two inputs, namely the first current If and the third voltage V3, and the output signal is the fourth voltage signal V4, and the fourth voltage signal V4 is used to drive the MOS-FET and its driving module, thereby controlling the power supply under test.

3. The programmable DC electronic load based on multi-mode compatible topology according to claim 1, characterized in that: It also includes a human-machine interface and a host computer software. The external mode instruction received by the main DSP controller is obtained from the human-machine interface or the host computer software. The external mode instruction includes the electronic load working in a specific mode or performing a mode switch.

4. A control method for a programmable DC electronic load based on a multi-mode compatible topology, used to control a programmable DC electronic load based on a multi-mode compatible topology as claimed in any one of claims 1 to 3, characterized in that: The main DSP controller adjusts the DAC multiplier and PGA to achieve CR load mode control. The main DSP controller adjusts the DAC multiplier, PGA and DAC1 to achieve LED load mode control. The main DSP controller adjusts the DAC multiplier and PGA gain, and adjusts DAC2 according to the measured current servo to achieve CV load mode control with adjustable feedback depth. The main DSP controller adjusts DAC2 to achieve CC load mode control, and realizes arbitrary mode switching between the four modes of CC, CR, CV and LED in a multi-mode compatible topology, and the switching process is continuous and uninterrupted.

5. The control method of a programmable DC electronic load based on a multi-mode compatible topology according to claim 4, characterized in that: In CC mode, the main DSP controller sets D_Rset to 0 and D_PGA to the maximum value. The multi-mode compatible topology serves as a current negative feedback loop. In the stable state, D_Iset=Iout*K4+B4, where Iout is the current signal of the power supply under test, and K4 and B4 are constants. The main DSP controller adjusts the size of D_Iset to achieve constant control of the current signal of the power supply under test in CC mode of the electronic load.

6. The control method of a programmable DC electronic load based on a multi-mode compatible topology according to claim 4, characterized in that: In CV mode, the main DSP controller adjusts D_PGA and D_Rset to the set feedback depth value D_Rset / D_PGA, and the multi-mode compatible topology serves as a voltage negative feedback loop. In a stable state, the servo adjustment realizes D_Iset=Iout*K4+B4, where Iout is the current signal of the power supply under test, and K4 and B4 are constants; at this time, D_Vset= K6*Vin+B6, K6 and B6 are constants; the main DSP controller realizes constant control of the voltage Vin of the power supply under test in the CV mode of the electronic load by adjusting the size of D_Vset.

7. The control method of a programmable DC electronic load based on a multi-mode compatible topology according to claim 4, characterized in that: In CR mode, the main DSP controller sets D_Vset and D_Iset to 0, and the multi-mode compatible topology is used as a resistor negative feedback loop. D_PGA / D_Rset=Vin / Iout*K5+B5, where K5 and B5 are constants. The main DSP controller adjusts the size of D_PGA and D_Rset to control the precise control of the equivalent impedance Vin / Iout of the power supply under test in the CR mode of the electronic load with the value of D_PGA / D_Rset.

8. The control method of a programmable DC electronic load based on a multi-mode compatible topology according to claim 4, characterized in that: In LED mode, it is equivalent to the series connection of a constant voltage source VF and an equivalent series resistor Rd. The main DSP controller sets D_Iset to 0, and the multi-mode compatible topology serves as the LED negative feedback loop. At this time, Iout= D_Rset / D_PGA*(D_Vset / 65535*Vref –(K1*Vin+B1)); the main DSP controller adjusts the size of D_Vset, D_PGA, and D_Rset to make D_Vset= K6*VF+B6; and makes D_PGA / D_Rset=Rd*K5+B5, where K1, B1, B5, K5, K6, and B6 are constants, and Vref is a constant; to achieve precise control of the start-up voltage VF and the equivalent series resistor Rd in the LED mode of the electronic load.

9. The control method of a programmable DC electronic load based on a multi-mode compatible topology according to claim 8, characterized in that: When switching from CC mode to CV mode, the main DSP controller adjusts D_PGA and D_Rset to the set feedback depth value, then adjusts D_Vset to the set voltage, and finally uses the measured value of the electronic load current to serve D_Iset to achieve switching; when switching from CC mode to CR mode, the main DSP controller first adjusts D_Vset to 0, then adjusts D_Iset to 0, and finally adjusts D_PGA and D_Rset to the set resistance value; when switching from CC mode to LED mode, the main DSP controller adjusts D_Vset to the set VF value, then adjusts D_Iset to 0, and finally adjusts D_PGA and D_Rset to the set resistance Rd value; When switching from CV mode to CC mode, the main DSP controller adjusts D_Rset to 0, adjusts D_PGA to 65535, and then adjusts D_Iset to the set current value; when switching from CV mode to CR mode, the main DSP controller adjusts D_PGA and D_Rset to the set resistance value, and then adjusts D_Vset to 0; when switching from CV mode to LED mode, the main DSP controller adjusts D_PGA and D_Rset to the set Rd value, and then adjusts D_Iset to 0, and finally adjusts D_Vset to the set VF value; When switching from CR mode to CC mode, the main DSP controller adjusts D_Rset to 0, adjusts D_PGA to 65535, and then adjusts D_Iset to the set current value; When switching from CR mode to CV mode, the main DSP controller adjusts D_Vset to the set voltage value, then adjusts D_Rset and D_PGA to the set feedback depth value, and finally uses the measured value of the electronic load current to servo D_Iset; when switching from CR mode to LED mode, the main DSP controller adjusts D_Vset to the set VF value, then adjusts D_Rset and D_PGA to the set Rd value; When switching from LED mode to CC mode, the main DSP controller adjusts D_Rset to 0, adjusts D_PGA to 65535, and then adjusts D_Iset to the set current value; when switching from LED mode to CV mode, the main DSP controller adjusts D_Rset and D_PGA to the set feedback depth, and then adjusts D_Vset to the set voltage value, and finally servo D_Iset with the measured value of the electronic load current; when switching from LED mode to CR mode, the main DSP controller adjusts D_Rset and D_PGA to the set resistance values, and then adjusts D_Vset to 0.

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