CN111179709B

CN111179709B - Digital multifunctional power electronic technology teaching experiment platform

Info

Publication number: CN111179709B
Application number: CN202010174288.XA
Authority: CN
Inventors: 郑诗程; 黄聪; 林峰
Original assignee: Anhui University of Technology AHUT
Current assignee: Anhui University of Technology AHUT
Priority date: 2020-03-13
Filing date: 2020-03-13
Publication date: 2022-03-08
Anticipated expiration: 2040-03-13
Also published as: CN111179709A

Abstract

The invention discloses a digital multifunctional power electronic technology teaching experiment platform, relating to the technical field of power electronics; the experimental platform comprises a protection circuit, a sampling circuit, a driving circuit, a DSP core control panel, a PC and a power electronic integrated main circuit, wherein the power electronic integrated main circuit comprises a single-phase half-wave controllable rectifying circuit, a single-phase bridge controllable rectifying circuit, a single-phase PWM rectifying circuit, a PWM generating and driving circuit, a Boost circuit, a Buck circuit, a square wave inverter circuit and an SPWM inverter circuit, and can be switched on and off as required to complete different experiments; the experiment platform integrates various experiment circuits, improves the comprehensiveness and the integration degree of the experiment platform, can realize the experiment functions of almost all experiment subjects in the basic experiment teaching process by matching with the corresponding experiment method, solves the problem that the equipment characteristics cannot be changed randomly in the traditional basic experiment teaching, and is convenient and flexible in the use process.

Description

Digital multifunctional power electronic technology teaching experiment platform

Technical Field

The invention relates to the technical field of power electronics, in particular to a digital multifunctional power electronic technology teaching experiment platform.

Background

The power electronic technology is a new electronic technology applied to the power field, and is a technology for converting and controlling electric energy by using power electronic devices (such as thyristors, GTOs, IGBTs and the like). Unlike information electronics technology, which is mainly used for power conversion, the "power" converted by the power electronics technology can be as large as hundreds of MW or even GW, or as small as several W or even 1W or less. The power electronic technology becomes an indispensable professional basic course for modern electrical engineering and automation, and plays an important role in cultivating the professional talents.

The power electronic technology is closely crossed with three colleges of electrical engineering (strong electricity), information engineering (weak electricity) and control engineering, is a bridge for connecting the weak electricity and the strong electricity, is one of the most active and fastest-developing new subjects at present, and is rapidly developed in recent 20 years. Aiming at the development requirement, the course reconstruction and experimental reform are needed in the power electronic technology course. The power electronic technology teaching equipment in the past mainly adopts analog circuit or special control chip mode to realize, mostly belongs to demonstration or verifiability experiment, and the hardware circuit is fixed, and the system characteristic can't change at will, and control mode is single and can't change, and is bulky, with high costs, has restricted the cultivation of student's hands-on ability and innovation ability.

Through search, the Chinese patent number ZL201610056810.8 has the invention name: digital power electronic and electric transmission real-time control experimental device and experimental method, the application date is: the experimental device disclosed in the application, 2016, 1, 27, comprises a computer, a data acquisition and real-time control module, a signal conversion module, a signal protection driving module, a pulse triggering module, a clock synchronization unit and a power electronic and electric transmission experimental pendant area; the application also includes a test method using the above device; the experimental device of this application can accomplish comprehensive power electronics and electric drive experiment. However, the experimental device provided in this application is bulky, and has the disadvantages of high cost and complicated experimental switching.

Disclosure of Invention

1. Technical problem to be solved by the invention

In view of the problems of fixed hardware circuit, incapability of randomly changing system characteristics, large volume and high cost of the conventional power electronic experiment platform, the invention provides a digital multifunctional power electronic technology teaching experiment platform, which integrates all experiments, realizes the purpose of reducing the volume by utilizing common parts of components, selects experiment contents through a toggle switch, is simple and convenient to switch the experiments, improves the comprehensiveness and the integration degree of the experiment platform, saves the cost and improves the use flexibility of the experiment platform.

2. Technical scheme

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

the invention discloses a digital multifunctional power electronic technology teaching experiment platform, which comprises a protection circuit, a sampling circuit, a driving circuit, a DSP core control panel, a PC (personal computer) and a power electronic integrated main circuit; the protection circuit is respectively and electrically connected with the sampling circuit and the DSP core control panel; the power electronic integrated main circuit is electrically connected with the DSP core control panel through a sampling circuit; the driving circuit comprises an MOS tube driving circuit and a thyristor driving circuit, and the driving circuit is respectively and electrically connected with the DSP core control board and the power electronic integrated main circuit; the DSP core control board is electrically connected with the PC, receives signals of the PC and feeds back the signals; the power electronic integrated main circuit comprises a single-phase half-wave controllable rectifying circuit, a single-phase bridge controllable rectifying circuit, a single-phase PWM rectifying circuit, a PWM generating and driving circuit, a Boost circuit, a Buck circuit, a square wave inverter circuit and an SPWM inverter circuit; the single-phase half-wave controllable rectifying circuit and the single-phase bridge controllable rectifying circuit use the same circuit, and the circuit comprises a current sensor, four thyristors, a plurality of toggle switches, a plurality of cement resistors and an inductor; the single-phase PWM rectification circuit, the PWM generation and driving circuit, the Boost circuit, the Buck circuit, the square wave inverter circuit and the SPWM inverter circuit share one circuit, and the circuit comprises an inductor, four power MOS (metal oxide semiconductor) tubes, a toggle switch, a cement resistor, an electrolytic capacitor, a CBB (cubic boron nitride) capacitor and a current sensor;

in the power electronic integrated main circuit, the input end of a1 st thyristor is connected with a power supply through a 14 th toggle switch and is simultaneously connected with the output end of a2 nd thyristor; the 1 st thyristor output end is respectively connected with the S5 end, the G5 end and the IP + terminal of the 3 rd current sensor of the thyristor driving circuit; the output end of the 2 nd thyristor is also connected with the S6 end and the G6 end of the thyristor driving circuit; the input end of the 2 nd thyristor is grounded and is divided into three paths, one path is connected to the IP-terminal of the 3 rd current sensor through the 106 th resistor and the 12 th toggle switch, the other path is connected to the IP-terminal of the 3 rd current sensor through the 105 th resistor, the 13 th toggle switch and the 6 th inductor, and the last path is connected with a power supply through the 16 th toggle switch and the 15 th toggle switch; the output end of the 3 rd thyristor is connected with the S7 end and the G7 end of the thyristor driving circuit and is connected to the IP + terminal of the 3 rd current sensor; the input end of the 3 rd thyristor is respectively connected with the output end of the 4 th thyristor and the 16 th toggle switch, and is connected with a power supply through the 15 th toggle switch; the 4 th thyristor output end is also connected with the S8 end and the G8 end of the thyristor drive circuit; the input end of the 4 th thyristor is connected with the input end of the 3 rd thyristor; the VCC terminal of the 3 rd current sensor is connected with a power supply and is grounded through a 48 th capacitor; the GND terminal is grounded and is connected to the sampling circuit through a 49 th capacitor; the VIOUT terminal is connected to the sampling circuit through a 132 th resistance terminal;

in the power electronic integrated main circuit, a1 st terminal of a1 st power MOS tube is connected with a G1 end of an MOS tube driving circuit, a2 nd terminal of the 1 st power MOS tube is connected with a power supply through a2 nd toggle switch and a1 st slide rheostat, and is connected with an IP + terminal of a1 st current sensor through a3 rd toggle switch; the 3 terminal of the 1 st power MOS tube is connected with the 2 terminal of the 2 nd power MOS tube, the two are simultaneously connected with the S1 terminal of the MOS tube driving circuit and the sampling circuit, the power supply is connected with the power supply through three inductors connected in series, a1 st toggle switch and a1 st sliding rheostat, the sampling circuit is connected with the sampling circuit through five inductors connected in series and a 10 th toggle switch, the IP + terminal of a1 st current sensor is connected with the IP + terminal of the 1 st current sensor through a 4 th toggle switch and a3 rd inductor, the 3 rd terminal of a3 rd power MOS tube and the 2 th terminal of the 4 th power MOS tube are respectively connected with the 3 rd terminal of the 3 rd power MOS tube and the 2 th terminal of the 4 th power MOS tube through a 5 th toggle switch, a 4 th inductor and a 122 th capacitor, the sampling circuit is connected with the 3 rd terminal of the 3 rd power MOS tube and the 2 th terminal of the 4 th power MOS tube through the 5 th toggle switch, the 4 th inductor and the 11 th toggle switch; the 1 terminal of the 2 nd power MOS transistor is connected with the G2 terminal of the MOS transistor driving circuit, the 3 terminal of the 2 nd power MOS transistor is connected with the S2 terminal of the MOS transistor driving circuit, and simultaneously the 1 st power MOS transistor is connected with one end of the 1 st slide rheostat through a 12 th diode, a 13 th diode, a 6 th resistor, a 120 th capacitor, a 121 th capacitor, a 43 th capacitor, a 153 th resistor and a 43 th capacitor and an 11 th diode; the current sensor is connected with an IP-terminal of the 1 st current sensor after being connected with a 9 th toggle switch through a 123 th capacitor, a 124 th capacitor, a1 st CBB capacitor and a2 nd CBB capacitor respectively; the 3 terminal of the 2 nd power MOS tube is connected to one end of a 6 th toggle switch, a 7 th toggle switch and an 8 th toggle switch through a 102 th resistor, a 103 th resistor and a 104 th resistor respectively, and the other end of the 6 th toggle switch, the 7 th toggle switch and the 8 th toggle switch is connected to the IP-terminal of the 1 st current sensor; the 3 terminal of the 2 nd power MOS tube is grounded; the 1 terminal of the 3 rd power MOS tube is connected with the G3 terminal of the MOS tube driving circuit; the 2 terminal of the 3 rd power MOS tube is connected with the IP + terminal of the 1 st current sensor; the 3 terminal of the 3 rd power MOS tube is respectively connected with the S3 terminal of the MOS tube driving circuit and the 2 terminal of the 4 th power MOS tube, and is connected to the sampling circuit; the 1 terminal of the 4 th power MOS tube is connected with the G4 terminal of the MOS tube driving circuit; the 3 terminal of the 4 th power MOS tube is respectively connected to the S4 terminal of the MOS tube driving circuit and the 3 terminal of the 2 nd power MOS tube; the IP-terminal of the 1 st current sensor is connected with a sampling circuit; the VCC terminal of the 1 st current sensor is connected with a power supply and is grounded through a 125 th capacitor; the output VIOUT terminal of the 1 st current sensor is connected to a sampling circuit after passing through a filter circuit consisting of a 27 th resistor and a 126 th capacitor.

Furthermore, the sampling circuit consists of a plurality of paths of current sensors, voltage sensors and peripheral circuits, is used for acquiring current signals and voltage signals in the experimental process and sending related signals to the DSP core control board, and comprises a direct current voltage sampling circuit, an alternating current voltage sampling circuit and a current sampling circuit.

Furthermore, the protection circuit consists of a comparator circuit and a logic gate circuit, the sampling circuit collects key voltage and current signals of the main circuit, the collected signals are compared with a set value through the comparator circuit, signals of 0 and 1 are output, the signals are sent to the logic gate circuit for logic judgment, finally, a judgment result is sent to the DSP core control board, and the DSP core control board processes whether to block the PWM output signal or not according to the received judgment result.

Furthermore, the experimental platform also comprises a power module consisting of an AC-DC power supply component, a DC-DC power supply component and a DC-DC voltage reduction circuit, wherein the power module is respectively connected with the protection circuit, the sampling circuit, the driving circuit and the DSP core control panel and provides power for the connected circuits.

Furthermore, the single-phase half-wave controllable rectifying circuit, the single-phase bridge controllable rectifying circuit and the single-phase PWM rectifying circuit are powered by a single-phase alternating current input power supply which comprises a transformer, an overcurrent protection circuit and an alternating current voltmeter.

Furthermore, the Boost circuit, the Buck circuit, the square wave inverter circuit and the SPWM inverter circuit are powered by a single-phase direct-current input power supply, and the single-phase direct-current input power supply comprises an AC/DC switching power supply, an overcurrent protection circuit and a direct-current voltmeter.

3. Advantageous effects

Compared with the prior art, the technical scheme provided by the invention has the following remarkable effects:

(1) in view of the fact that basic experiment teaching equipment is simple in the prior art, the basic experiment teaching equipment is mainly constructed by old analog circuits or a DSP control circuit is arranged in each type of experiment table, hardware circuits are fixed, system characteristics cannot be changed randomly, and the problem of high cost is solved.

(2) In view of the problem that the flexibility of the existing experiment platform is poor due to the fact that different experiments are carried out in the mode that the existing experiment platform uses modules for mounting, the experiment platform is provided with the toggle switch, different experiment circuits are built through the switching of the toggle switch, and the flexibility of the experiment platform is improved. Meanwhile, the experiment platform of the invention utilizes the PC to select different experiments, thereby facilitating the control of different experiments by users.

(3) The experiment platform is provided with the protection circuit, and in the experiment process, if the circuit fails, the output is automatically cut off, so that the safe experiment is ensured. Simultaneously, the experiment platform is also provided with a sampling circuit and a PC, current and voltage signals in the experiment process are collected through the sampling circuit, and are transmitted to the PC to be displayed in a digital quantity form, so that a user can obtain an experiment result visually, and the experiment platform is convenient to use.

Drawings

FIG. 1 is a block diagram of an experimental platform architecture of the present invention;

FIG. 2 is an operation interface of an upper computer of the experiment platform in the invention;

FIG. 3 is an operation interface of the single-phase half-wave controllable rectification experiment in the present invention;

FIG. 4 is a general experimental circuit diagram of the experimental platform of the present invention;

FIG. 5 is a general circuit diagram of a sampling circuit in the present invention;

fig. 6 (a) and (b) are diagrams of an ac voltage sampling circuit of the present invention;

FIGS. 6 (c) and (d) are current sampling circuit diagrams of the sampling circuit of the present invention;

fig. 6 (e) is a dc voltage sampling circuit diagram of the sampling circuit of the present invention;

FIG. 7 is a circuit diagram of a protection circuit of the present invention;

FIG. 8 is a driving circuit diagram of the power MOS transistor of the present invention;

FIG. 9 is a circuit diagram of a thyristor driver circuit according to the present invention;

FIG. 10 is a circuit diagram of a resistive load test with single-phase half-wave controllable rectification according to the present invention;

FIG. 11 is a circuit diagram of a resistive-inductive load experiment of a single-phase half-wave controllable rectifier according to the present invention;

FIG. 12 is a circuit diagram of a resistive load test of the single-phase bridge type fully-controlled rectifier of the present invention;

FIG. 13 is a circuit diagram of a resistive-inductive load experiment of the single-phase bridge type full-controlled rectifier of the present invention;

FIG. 14 is a circuit diagram of a single-phase PWM rectification experiment in accordance with the present invention;

FIG. 15 is a circuit diagram of a Boost test in the present invention;

FIG. 16 is a Buck test circuit diagram according to the present invention;

FIG. 17 is a circuit diagram of the square wave inversion and SPWM inversion experiment of the present invention;

FIG. 18 is a circuit diagram of the DSP and the upper computer communication circuit of the present invention.

Detailed Description

For a further understanding of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings and examples.

Example 1

With reference to fig. 1, the digital multifunctional power electronic technology teaching experiment platform of the embodiment includes a protection circuit, a sampling circuit, a driving circuit, a DSP core control board, a PC, and a power electronic integrated main circuit. The protection circuit is respectively and electrically connected with the sampling circuit and the DSP core control panel. The power electronic integrated main circuit is electrically connected with the DSP core control panel through the sampling circuit. The driving circuit comprises an MOS tube driving circuit and a thyristor driving circuit, and the driving circuit is respectively and electrically connected with the DSP core control board and the power electronic integrated main circuit. The DSP core control board is electrically connected with the PC, receives signals of the PC and feeds back the signals.

Referring to fig. 18, the DSP core control board uses LaunchPad 28027 manufactured by TI for analog-to-digital (AD) conversion, digital-to-analog (DA) conversion, and digital input/output (IO), and is connected to a PC through an RS 232-to-USB interface and performs real-time bidirectional communication.

With reference to fig. 5, the sampling circuit is composed of multiple current sensors, voltage sensors and peripheral circuits, and is configured to obtain current signals and voltage signals during an experiment, send related signals to the DSP core control board to perform analog-to-digital conversion, and send the converted digital quantity to the PC. The sampling circuit comprises direct-current voltage sampling, alternating-current voltage sampling and current sampling:

referring to fig. 6 (e), dc voltage sampling: the direct-current voltage of the main circuit is subjected to voltage division through a resistor, signal detection is achieved through the HCNR200 chip, the direct-current voltage is isolated from the main circuit, signals on the output side are conditioned through an operational amplifier, and then the signals are output to be 0-3.3V and are transmitted to an AD pin of the DSP core controller to be subjected to AD conversion.

Referring to fig. 6 (a) and (b), ac voltage sampling: the alternating voltage of the main circuit is subjected to signal detection through a voltage transformer and is isolated from the main circuit, and the signal at the output side is conditioned through an operational amplifier and then output to be 0-3.3V and is transmitted to an AD pin of the DSP core controller for AD conversion.

Referring to fig. 6 (c) and (d), current sampling: the current of the main circuit is subjected to signal detection through the current sensor and isolated from the main circuit, and the output signal is conditioned through the operational amplifier and then is output into a 0-3.3V signal which is transmitted to an AD pin of the DSP core controller for AD conversion.

With reference to fig. 7, the protection circuit is composed of a comparator circuit and a logic gate circuit, the sampling circuit collects the key voltage and current signals of the main circuit, the collected signals are compared with a set value through the comparator circuit, 0 and 1 signals are output, the signals are sent to the logic gate circuit for logic judgment, finally, the judgment result is sent to the DSP digital controller, and the DSP processes whether to block the PWM output signal or not according to the received judgment result.

With reference to fig. 8 and 9, the driving circuit of the present embodiment is composed of a power MOS transistor driving circuit and a thyristor driving circuit. In the power MOS tube driving circuit, a PWM signal sent by a DSP core control board is amplified by an MC1413 chip, the amplified PWM signal generates a signal capable of driving an MOS tube after passing through a TLP250 chip and a peripheral circuit, the driving circuit is isolated from a main circuit, and the main circuit is prevented from generating interference on a control circuit. In the thyristor drive circuit, a drive signal sent by a DSP core control board is amplified through an MC1413 chip, the amplified drive signal is isolated through a TLP521_2 optical coupling isolation chip, and the isolated signal generates a trigger signal through a pulse trigger circuit to drive a thyristor in a main circuit.

With reference to fig. 4, the power electronics integrated main circuit of the present embodiment includes: the single-phase half-wave controllable rectifying circuit, the single-phase bridge controllable rectifying circuit, the single-phase PWM rectifying circuit, the PWM generating and driving circuit, the Boost circuit, the Buck circuit, the square wave inverter circuit and the SPWM inverter circuit. A power MOS tube driving circuit in the driving circuit is respectively connected with a single-phase PWM (pulse-width modulation) rectifying circuit, a PWM generating and driving circuit, a Boost circuit, a Buck circuit, a square wave inverter circuit and an SPWM inverter circuit; the thyristor driving circuit is respectively connected with the single-phase half-wave controllable rectifying circuit and the single-phase bridge full-controlled rectifying circuit. The driving circuit is used for providing signal driving for the connected circuit. The sampling circuit is respectively connected with the single-phase half-wave controllable rectifying circuit, the single-phase bridge controllable rectifying circuit, the single-phase PWM rectifying circuit, the PWM generating and driving circuit, the Boost circuit, the Buck circuit, the square wave inverter circuit and the SPWM inverter circuit and is used for converting voltage signals and current signals on the connected circuits to obtain analog signals convenient to collect.

In the power electronic integrated main circuit of the embodiment, the single-phase half-wave controllable rectifying circuit and the single-phase bridge controllable rectifying circuit share one circuit, and the circuit comprises a current sensor, four thyristors, a toggle switch, a cement resistor and an inductor; the input end of the 1 st thyristor S1 is connected with the power supply through a 14 th toggle switch W14 and is simultaneously connected with the output end of the 2 nd thyristor S2; the output end of the 1 st thyristor S1 is respectively connected with the S5 end of the thyristor driving circuit, the G5 end of the thyristor driving circuit and the IP + terminal of the 3 rd current sensor A3; the output end of the 2 nd thyristor S2 is also connected with the S6 end and the G6 end of the thyristor driving circuit; the input end of the 2 nd thyristor S2 is divided into three paths while being grounded, one path is connected to the IP-terminal of the 3 rd current sensor A3 through a 106 th resistor R106 and a 12 th toggle switch W12, the other path is connected to the IP-terminal of the 3 rd current sensor A3 through a 105 th resistor R105, a 13 th toggle switch W13 and a 6 th inductor L6, and the last path is connected to a power supply through a 16 th toggle switch W16 and a 15 th toggle switch W15; the output end of the 3 rd thyristor S3 is connected with the ends S7 and G7 of the thyristor drive circuit and is connected to the IP + terminal of the 3 rd current sensor A3; the input end of the 3 rd thyristor S3 is respectively connected with the output end of the 4 th thyristor S4 and the 16 th toggle switch W16, and is connected with a power supply through the 15 th toggle switch W15; the 4 th thyristor S4 output end is also connected with the S8 end and the G8 end of the thyristor drive circuit; the input end of the 4 th thyristor S4 is connected with the input end of the 3 rd thyristor S3; the VCC terminal of the 3 rd current sensor A3 is connected with a power supply and is grounded through a 48 th capacitor C48; the GND terminal is grounded and is connected to a sampling circuit through a 49 th capacitor C49; the VIOUT terminal is connected to the sampling circuit through a 132 th resistor R132 terminal.

In the embodiment, the single-phase PWM rectification circuit, the PWM generation and driving circuit, the Boost circuit, the Buck circuit, the square wave inverter circuit and the SPWM inverter circuit share one circuit, and the circuit comprises an inductor, four power MOS (metal oxide semiconductor) tubes, a toggle switch, a cement resistor, an electrolytic capacitor, a CBB (cubic boron nitride) capacitor and a current sensor; the 1 st terminal of the 1 st power MOS tube M1 is connected with the G1 terminal of the MOS tube driving circuit, the 2 nd terminal of the 1 st power MOS tube M1 is connected with the power supply through a2 nd toggle switch W2 and a1 st slide rheostat B1, and is connected with the IP + terminal of the 1 st current sensor A1 through a3 rd toggle switch W3; the 3 terminal of the 1 st power MOS transistor M1 is connected with the 2 terminal of the 2 nd power MOS transistor M2, both of which are connected with the S1 terminal of the MOS transistor driving circuit and the sampling circuit, a power supply is connected with a power supply through three inductors in series, a1 st toggle switch W1 and a1 st sliding rheostat B1, a sampling circuit is connected with a sampling circuit through five inductors in series and a 10 th toggle switch W10, an IP + terminal of a1 st current sensor A1 is connected with a 4 th toggle switch W4 and a3 rd inductor L3, a3 rd terminal of a3 rd power MOS tube M3 and a2 th terminal of a 4 th power MOS tube M4 are respectively connected with a 5 th toggle switch W5, a 4 th inductor L4 and a 122 th capacitor C122, a3 rd terminal of the 3 rd power MOS tube M3 and a2 nd terminal of a 4 th power MOS tube M4 are respectively connected with a 5 th toggle switch W5, a 4 th inductor L4 and a 101 th resistor R101, a sampling circuit is connected with a3 rd terminal of a3 rd power MOS tube M3 and a2 nd terminal of a 4 th power MOS tube M4 are respectively connected with a 5 th toggle switch W5 and a 4 th inductor L4 through a 11 th toggle switch W11; the 1 terminal of the 2 nd power MOS tube M2 is connected with the G2 terminal of the MOS tube driving circuit, the 3 terminal of the 2 nd power MOS tube M2 is connected with the S2 terminal of the MOS tube driving circuit, and simultaneously the 1 st power MOS tube M1 terminal is connected with one end of the 1 st slide rheostat B1 terminal through a 12 th diode D12, a 13 th diode D13 and a 6 th resistor R6, a 120 th capacitor C120, a 121 th capacitor C121, a 43 th capacitor C43 and a 153 th resistor R153 and a 43 th capacitor C43 and an 11 th diode D11 respectively; the current sensor is connected to an IP-terminal of a1 st current sensor A1 after being connected to a 9 th toggle switch W9 through a 123 th capacitor C123, a 124 th capacitor C124, a1 st CBB capacitor CBB1 and a2 nd CBB capacitor CBB 2; the 3 terminal of the 2 nd power MOS 2 is connected to one end of a 6 th toggle switch W6, a 7 th toggle switch W7 and an 8 th toggle switch W8 through a 102 th resistor R102, a 103 th resistor R103 and a 104 th resistor R104 respectively, and the other end of the 6 th toggle switch W6, the 7 th toggle switch W7 and the 8 th toggle switch W8 are connected to an IP-terminal of a current sensor A1; the 3 terminal of the 2 nd power MOS transistor M2 is grounded; the 1 terminal of the 3 rd power MOS transistor M3 is connected with the G3 terminal of the MOS transistor drive circuit; the 2 terminal of the 3 rd power MOS transistor M3 is connected with the IP + terminal of the 1 st current sensor A1; the 3 terminal of the 3 rd power MOS transistor M3 is respectively connected with the S3 terminal of the MOS transistor driving circuit and the 2 terminal of the 4 th power MOS transistor M4, and is connected to the sampling circuit; the 1 terminal of the 4 th power MOS transistor M4 is connected with the G4 terminal of the MOS transistor drive circuit; the 3 terminals of the 4 th power MOS transistor M4 are respectively connected to the S4 terminal of the MOS transistor driving circuit and the 3 terminal of the 2 nd power MOS transistor M2; the IP-terminal of the 1 st current sensor A1 is connected with a sampling circuit; the VCC terminal of the 1 st current sensor A1 is connected to the power supply, and is grounded through the 125 th capacitor C125; the output VIOUT terminal of the 1 st current sensor A1 passes through a filter circuit consisting of a 27 th resistor R27 and a 126 th capacitor C126 and then is connected to a sampling circuit.

The experimental platform of the embodiment further comprises a single-phase alternating-current input power supply, a single-phase direct-current input power supply and a power supply module. The single-phase alternating current input power supply consists of a transformer, an overcurrent protection circuit and an alternating current voltmeter, is respectively connected with the single-phase half-wave controllable rectifying circuit, the single-phase bridge controllable rectifying circuit and the single-phase PWM rectifying circuit, and is used for providing the alternating current input power supply for the connected circuits. The single-phase direct-current input power supply consists of an AC/DC switching power supply, an overcurrent protection circuit and a direct-current voltmeter, is respectively connected with the Boost circuit, the Buck circuit, the square wave inverter circuit and the SPWM inverter circuit, and is used for providing a direct-current input power supply for the connected circuits. The power supply module comprises an AC-DC power supply module (model: HE24P24 LRN), a DC-DC power supply module (model: B2424S-2WR2, B2415S-2WR2, B2405S-2WR2, VRA2415YMD-6WR 3) and a DC-DC voltage reduction circuit, and the DC-DC voltage reduction circuit is respectively connected with the protection circuit, the sampling circuit, the driving circuit and the DSP core control board and is used for providing direct current power supplies of +24V, +15V, -15V, +5V and +3.3V required by system control for the connected circuits.

The experiment platform of this embodiment is used to carry out the experiment, can build different main circuits through toggle switch, accomplishes different experiments.

With reference to fig. 10 and 11, the single-phase half-wave controllable rectifier circuit of the present embodiment is divided into two parts: the single-phase half-wave controllable rectifying circuit comprises a single-phase half-wave controllable rectifying circuit with a resistance load and a single-phase half-wave controllable rectifying circuit with an inductance load. The single-phase half-wave controllable rectifying circuit with resistance load is composed of a thyristor, a toggle switch and a cement resistor. The single-phase half-wave controllable rectifying circuit with the inductance-resistance load consists of a thyristor, a toggle switch, a cement resistor and an inductor. The method is used for single-phase half-wave controllable rectification experiments.

With reference to fig. 12 and 13, the single-phase bridge fully-controlled rectifier circuit of the present embodiment is divided into two parts: the single-phase bridge type full-control rectification circuit with the resistance load and the single-phase bridge type full-control rectification circuit with the inductance load. The single-phase bridge type full-control rectifying circuit with the resistance load consists of four thyristors, a toggle switch and a cement resistor. The single-phase bridge type full-control rectifier circuit with the resistance-inductance load consists of four thyristors, a toggle switch, a cement resistor and an inductor. The method is used for single-phase bridge type full-control rectification experiments. The single-phase half-wave controllable rectifying circuit and the single-phase bridge type full-control rectifying circuit are distributed on the same main circuit, and different main circuits are built through a toggle switch.

With reference to fig. 14, the single-phase PWM rectification circuit is composed of an inductor, four power MOS transistors, a toggle switch, a cement resistor, an electrolytic capacitor, and a CBB capacitor, and is used for a single-phase PWM rectification experiment. The PWM generating and driving circuit consists of a DSP core control board, a driving chip and a peripheral circuit thereof and is used for PWM generating and driving experiments. The Boost circuit consists of an inductor, a power MOS (metal oxide semiconductor) tube, a toggle switch, a cement resistor, an electrolytic capacitor and a CBB (cubic boron nitride) capacitor (see FIG. 15) and is used for Boost experiments. The Buck circuit consists of an inductor, a power MOS (metal oxide semiconductor) tube, a toggle switch, a cement resistor, an electrolytic capacitor and a CBB (refer to FIG. 16) and is used for Buck experiments. The square wave inverter circuit and the SPWM inverter circuit use the same circuit, are composed of an inductor, a power MOS tube, a toggle switch, a CBB capacitor and a cement resistor (see figure 17), and are used for a square wave inverter experiment and an SPWM inverter experiment. The specific steps of each experiment are as follows:

a user selects experiment contents and parameters on a control interface of the upper computer, the PC sends a control instruction to the DSP core control panel according to the selected contents, the DSP core control panel sends a driving signal according to the instruction contents, and the driving signal is amplified by the driving circuit and then drives the MOS tube and the thyristor on the main circuit to complete the experiment.

The voltage and current parameters of the main experimental circuit are converted into signals which can be identified by the DSP through the sampling circuit, the signals are converted into discrete digital quantities after being subjected to AD conversion by the DSP core control board, and then the digital quantities are sent to the PC to be displayed in a dynamic graph mode to replace an oscilloscope to monitor the voltage and current parameters in the circuit.

For single-phase half-wave controllable rectification experiments, single-phase bridge full-control rectification experiments and single-phase PWM rectification experiments, zero-crossing detection can be realized through a software algorithm, the phase of input alternating voltage is calculated according to the zero-crossing detection, and finally a trigger signal or a PWM signal is sent out. Taking single-phase zero-crossing detection of a single-phase half-wave controllable rectification experiment as an example, the specific process comprises the following steps:

step 1: the single-phase alternating current output by the transformer is input to the sampling circuit for conversion.

Step 2: and (3) transmitting the signals converted in the step (1) to a DSP core control board for quantization to be converted into digital quantity.

And step 3: and judging whether the input alternating current is a positive zero crossing or a negative zero crossing according to the digital quantity, and sending corresponding indication information.

And 4, step 4: and returning to the step 1, and continuously judging the zero crossing point.

In this embodiment, the PC obtains the trigger angle selected by the user in the operation interface of the upper computer, and sends the trigger angle to the DSP core control board. Judging the zero crossing point of the single-phase alternating current input voltage, calculating the real-time phase of the input alternating current voltage according to the zero crossing point, sending a driving signal when the phase of the alternating current signal reaches a set trigger angle, amplifying the driving signal by a pulse trigger in a driving circuit, and then transmitting the amplified driving signal to a single-phase half-wave controllable rectifying circuit and a single-phase bridge type full-controlled rectifying circuit.

The single-phase half-wave controllable rectification experiment comprises the following specific steps:

step 1: the 12 th toggle switch W12, the 14 th toggle switch W14, the 15 th toggle switch W15, the 16 th toggle switch W16 and the 17 th toggle switch W17 are in an ON state, and other switches are in an OFF state, so that the main circuit is in a single-phase half-wave controllable rectification resistive load state. Or the 13 th toggle switch W13, the 14 th toggle switch W14, the 15 th toggle switch W15, the 16 th toggle switch W16, the 17 th toggle switch W17 and the 19 th toggle switch W19 are in an ON state, and other switches are in an OFF state, so that the main circuit is in a single-phase half-wave controllable rectification load state with inductance resistance. Then the AC power supply is switched on.

Step 2: and selecting a single-phase half-wave controllable rectification experiment on the operation interface of the upper computer shown in fig. 2, and entering a control interface of the corresponding experiment shown in fig. 3.

And step 3: and selecting a trigger angle on a control interface of the upper computer, and acquiring the trigger angle selected by a user in an operation interface of the upper computer by the PC and sending the trigger angle to the DSP core control board.

And 4, step 4: the DSP core control board judges the zero crossing point of the single-phase alternating current input voltage according to the signal sent by the sampling circuit, calculates the real-time phase of the input alternating current voltage according to the zero crossing point, and sends a driving signal when the phase of the alternating current signal reaches the set triggering angle.

And 5: the driving signal is amplified by a pulse trigger in the driving circuit and then is sent to the single-phase half-wave controllable rectifying circuit.

Step 6: the voltage and current parameters of the main circuit are converted into signals which can be identified by the DSP through the sampling circuit, the signals are converted into discrete digital quantities after being subjected to AD conversion by the DSP core control board, and then the digital quantities are sent to the PC to be displayed in a dynamic graph mode.

And 7: returning to step 3.

The single-phase bridge type full-control rectification experiment specifically comprises the following steps:

step 1: the 12 th toggle switch W12, the 14 th toggle switch W14, the 15 th toggle switch W15 and the 17 th toggle switch W17 are in an ON state, and other switches are in an OFF state, so that the main circuit is in a single-phase bridge type fully-controlled rectifier resistance load state. Or the 13 th toggle switch W13, the 14 th toggle switch W14, the 15 th toggle switch W15, the 17 th toggle switch W17 and the 19 th toggle switch W19 are in an ON state, and other switches are in an OFF state, so that the main circuit is in a resistance-inductance load state of the single-phase bridge type full-control rectifier. Then the AC power supply is switched on.

Step 2: and selecting a single-phase bridge type full-control rectification experiment on the operation interface of the upper computer, and entering a control interface of the corresponding experiment.

And 5: the driving signal is amplified by a pulse trigger in the driving circuit and then is sent to the single-phase bridge type full-control rectifying circuit.

And 7: returning to step 3.

The experimental method of the embodiment further comprises the steps that the PC machine obtains the switching frequency and the duty ratio set by the user on the operation interface of the upper computer and sends the switching frequency and the duty ratio to the DSP core control board; the DSP core control board sends out corresponding PWM signals according to the switching frequency and the duty ratio, and the PWM signals are amplified by a TLP250 chip in the driving circuit and then sent to the Buck circuit and the Boost circuit.

The Buck experiment and Boost experiment have the following specific steps:

step 1: according to the toggle switch of the experimental content, Buck experiment 2 nd toggle switch W2, 4 th toggle switch W4, 7 th toggle switch W7, 8 th toggle switch W8, 18 th toggle switch W18 are in the ON state, Boost experiment 1 st toggle switch W1, 3 rd toggle switch W3, 7 th toggle switch W7, 9 th toggle switch W9, 17 th toggle switch W17 is in the ON state, other switches are in the OFF state, make the main circuit be in Buck circuit or Boost circuit state, then connect into DC power supply.

Step 2: and selecting a Buck converter experiment or a Boost converter experiment on the operation interface of the upper computer, and entering a control interface of the corresponding experiment.

And step 3: and the control interface of the upper computer selects the switching frequency and the duty ratio, and the PC acquires the parameters selected by the user in the operation interface of the upper computer and sends the parameters to the DSP core control board.

And 4, step 4: and the DSP core control board sends out corresponding PWM signals according to the selected parameters.

And 5: the PWM signal is amplified by a TLP250 chip in the driving circuit and then is sent to a Buck circuit and a Boost circuit.

And 7: returning to step 3.

When a single-phase PWM rectification experiment is carried out, the PC machine obtains a target voltage value Vref set by a user on an operation interface of the upper computer and sends the target voltage value Vref to the DSP core control board; the sampling circuit samples an output voltage value Vout in real time, the Vout-Vref outputs a modulation ratio MI after calculation, the DSP core control board sends an SPWM signal which has the same phase as the output voltage of the transformer and has the modulation ratio MI, and the SPWM signal is amplified by a TLP250 chip in the driving circuit and then is sent to the single-phase PWM rectifying circuit.

The single-phase PWM rectification experiment comprises the following specific steps:

step 1: the 3 rd toggle switch 3, the 6 th toggle switch 6, the 9 th toggle switch 9, the 10 th toggle switch 10, the 11 th toggle switch 11 and the 17 th toggle switch 17 are in an ON state, and other switches are in an OFF state, so that the main circuit is in a single-phase PWM rectification circuit state and then is connected into an alternating current power supply.

Step 2: and selecting a single-phase PWM rectification experiment on an operation interface of the upper computer, and entering a control interface of the experiment.

And step 3: and the control interface of the upper computer selects and outputs a given voltage, and the PC acquires the given voltage selected by the user in the operation interface of the upper computer and sends the given voltage to the DSP core control board.

And 4, step 4: the DSP core control board judges the zero crossing point of the single-phase alternating current input voltage according to the signal sent by the sampling circuit, calculates the real-time phase of the input alternating current voltage according to the zero crossing point, and then sends out a corresponding PWM signal according to the phase and the selected parameter.

And 5: the PWM signal is amplified by a TLP250 chip in the driving circuit and then is sent to a single-phase PWM rectifying circuit.

And 7: returning to step 3.

When a square wave inversion experiment and an SPWM inversion experiment are carried out, the PC acquires an inversion mode selected by a user on an operation interface of the upper computer and sends the inversion mode to the DSP core control board; the DSP core control board sends out PWM signals according to an inversion mode, and the PWM signals are amplified by a TLP250 chip in the driving circuit and then sent to the square wave inversion circuit and the SPWM inversion circuit.

The square wave inversion experiment and the SPWM inversion experiment comprise the following specific steps:

step 1: the 2 nd toggle switch 2, the 3 rd toggle switch 3 and the 5 th toggle switch 5 are in an ON state, other switches are in an OFF state, so that the main circuit is in a square wave inversion state and an SPWM inversion state, and then is connected to a direct current power supply.

Step 2: and selecting a square wave inversion experiment or an SPWM inversion experiment on an upper computer operation interface shown in FIG. 2, and entering a control interface of the corresponding experiment.

And step 3: and the control interface of the upper computer selects an inversion mode, and the PC acquires the inversion mode selected by the user in the operation interface of the upper computer and sends the inversion mode to the DSP core control board.

And 4, step 4: and the DSP core control board sends out corresponding PWM signals according to the inversion mode.

And 5: the PWM signal is amplified by a TLP250 chip in the driving circuit and then is sent to a square wave inverter circuit and an SPWM inverter circuit.

Step 6: the input and output voltage parameters of the main circuit are converted into signals which can be identified by the DSP through the sampling circuit, the signals are converted into discrete digital quantities after being subjected to AD conversion by the DSP core control board, and then the digital quantities are sent to the PC to be displayed in a dynamic graph mode.

And 7: returning to step 3.

The PC control interface program of the embodiment is written in a QT form in C language, the input and output voltages of each experimental circuit are visually and graphically displayed through the experimental control interface to obtain an experimental control interface, the experimental control interface is connected with the control program, and different experimental types are selected through buttons in the experimental control interface; the code is compiled in the CCS and downloaded to the DSP core control board, and when the experiment is carried out, the DSP core control board and the PC carry out real-time two-way communication to complete each experiment, so that the digital experiment device is a real digital experiment device. The experimental equipment and the real-time control program provided by the embodiment can realize various experimental verifications, get rid of the defect of singleness of the previous power electronic experiment, have comprehensiveness and developability, adapt to the digital real-time control experimental device and the method required by the development of the power electronic technology, and have a high-precision control system for the comprehensive power electronic experiment. And each experiment is provided with an experiment panel, and during experimental verification, data and waveforms such as operating parameters, input and output voltages and the like are displayed on an experiment control interface in real time, so that the method is clear and convenient to analyze and compare, and each experiment can be built into different main circuits only by toggling related switches, so that the method is convenient and efficient, and is suitable for research power electronic experiment requirements of senior students in the academia.

According to the digital multifunctional power electronic technology experiment platform and the operation method provided by the embodiment, a single-phase half-wave controllable rectification experiment can be completed through a single-phase half-wave controllable rectification circuit of the experiment platform; the single-phase bridge type full-control rectification experiment can be completed through the single-phase bridge type full-control rectification circuit; the PWM generating and driving experiment can be completed through the PWM generating and driving circuit; the Buck experiment can be completed through the Buck circuit; the Boost circuit can complete the Boost experiment; the square wave inversion experiment can be realized through the square wave inversion circuit; the SPWM inversion experiment is completed through the SPWM inversion circuit; the single-phase PWM rectification experiment can be completed through the single-phase PWM rectification circuit. Compared with the prior art, basic experiment teaching equipment is simple and mainly adopts an old analog circuit, or a scheme with high cost and poor flexibility is almost provided with a DSP control circuit in each kind of experiment table. The embodiment realizes that the experiment functions of almost all experiment subjects in the basic experiment teaching process are realized by only adopting a DSP chip as a core control board and integrating the circuit with each experiment, improves the comprehensiveness and the integration degree of the experiment platform, saves the cost and improves the use flexibility of the experiment platform.

The present invention and its embodiments have been described above schematically, without limitation, and what is shown in the drawings is only one of the embodiments of the present invention, and the actual structure is not limited thereto. Therefore, if the person skilled in the art receives the teaching, without departing from the spirit of the invention, the person skilled in the art shall not inventively design the similar structural modes and embodiments to the technical solution, but shall fall within the scope of the invention.

Claims

1. The utility model provides a multi-functional power electronic technology teaching experiment platform of digital, includes protection circuit, sampling circuit, drive circuit, DSP core control panel and PC, its characterized in that: the power electronic integrated main circuit is also included; the protection circuit is respectively and electrically connected with the sampling circuit and the DSP core control panel; the power electronic integrated main circuit is electrically connected with the DSP core control panel through a sampling circuit; the driving circuit comprises an MOS tube driving circuit and a thyristor driving circuit, and the driving circuit is respectively and electrically connected with the DSP core control board and the power electronic integrated main circuit; the DSP core control board is electrically connected with the PC, receives signals of the PC and feeds back the signals; the power electronic integrated main circuit comprises a single-phase half-wave controllable rectifying circuit, a single-phase bridge controllable rectifying circuit, a single-phase PWM rectifying circuit, a PWM generating and driving circuit, a Boost circuit, a Buck circuit, a square wave inverter circuit and an SPWM inverter circuit; the single-phase half-wave controllable rectifying circuit and the single-phase bridge controllable rectifying circuit use the same circuit, and the circuit comprises a current sensor, four thyristors, a plurality of toggle switches, a plurality of cement resistors and an inductor; the single-phase PWM rectification circuit, the PWM generation and driving circuit, the Boost circuit, the Buck circuit, the square wave inverter circuit and the SPWM inverter circuit share one circuit, and the circuit comprises an inductor, four power MOS (metal oxide semiconductor) tubes, a toggle switch, a cement resistor, an electrolytic capacitor, a CBB (cubic boron nitride) capacitor and a current sensor;

in the power electronic integrated main circuit, the input end of a1 st thyristor (S1) is connected with a power supply through a 14 th toggle switch (W14) and is simultaneously connected with the output end of a2 nd thyristor (S2); the output end of the 1 st thyristor (S1) is respectively connected with the S5 end of the thyristor driving circuit, the G5 end of the thyristor driving circuit and the IP + terminal of the 3 rd current sensor (A3); the output end of the 2 nd thyristor (S2) is also connected with the S6 end and the G6 end of the thyristor driving circuit; the input end of the 2 nd thyristor (S2) is grounded and divided into three paths, one path is connected to the IP-terminal of the 3 rd current sensor (A3) through the 106 th resistor (R106) and the 12 th toggle switch (W12), the other path is connected to the IP-terminal of the 3 rd current sensor (A3) through the 105 th resistor (R105), the 13 th toggle switch (W13) and the 6 th inductor (L6), and the last path is connected with a power supply through the 16 th toggle switch (W16) and the 15 th toggle switch (W15); the output end of the 3 rd thyristor (S3) is connected with the S7 end and the G7 end of the thyristor driving circuit, and is connected to the IP + terminal of the 3 rd current sensor (A3); the input end of the 3 rd thyristor (S3) is respectively connected with the output end of the 4 th thyristor (S4) and the 16 th toggle switch (W16), and is connected with a power supply through the 15 th toggle switch (W15); the output end of the 4 th thyristor (S4) is also connected with the S8 end and the G8 end of the thyristor driving circuit; the input end of the 4 th thyristor (S4) is connected with the input end of the 3 rd thyristor (S3); the VCC terminal of the 3 rd current sensor (A3) is connected to a power supply, and is grounded through a 48 th capacitor (C48); the GND terminal is grounded and is connected to a sampling circuit through a 49 th capacitor (C49); the VIOUT terminal is connected to the sampling circuit through a 132 th resistor (R132) terminal;

in the power electronic integrated main circuit, a1 terminal of a1 st power MOS (M1) is connected with a G1 terminal of a MOS drive circuit, a2 terminal of the 1 st power MOS (M1) is connected with a power supply through a2 nd toggle switch (W2) and a1 st slide rheostat (B1), and is connected with an IP + terminal of a1 st current sensor (A1) through a3 rd toggle switch (W3); the 3 terminal of the 1 st power MOS (M1) is connected with the 2 terminal of the 2 nd power MOS (M2), the two are simultaneously connected with the S1 terminal of the MOS driving circuit and the sampling circuit, the power supply is connected with the 1 st toggle switch (W1) and the 1 st sliding rheostat (B1) through three inductors connected in series, the sampling circuit is connected with the five inductors connected in series and the 10 th toggle switch (W10), the IP + terminal of the 1 st current sensor (A1) is connected with the 4 th toggle switch (W4) and the 3 rd inductor (L3), the 3 terminal of the 3 rd power MOS (M3) and the 2 terminal of the 4 th power MOS (M4) are respectively connected with the 3 terminal of the 3 th power MOS (M3) through the 5 th toggle switch (W5), the 4 th inductor (L4) and the 122 th capacitor (C122), and the 3 th flip switch (W5), the 4 th inductor (L4) and the 101 st resistor (R101) are respectively connected with the 3 rd power MOS terminal of the M3 and the 2 terminal of the 2 th power MOS 4, the sampling circuit is connected with a 4 th inductor (L4) through a 5 th toggle switch (W5), and the 3 rd terminal of a3 rd power MOS (M3) and the 2 nd terminal of a 4 th power MOS (M4) are connected through an 11 th toggle switch (W11); the 1 terminal of the 2 nd power MOS (M2) is connected with the G2 terminal of the MOS driving circuit, the 3 terminal of the 2 nd power MOS (M2) is connected with the S2 terminal of the MOS driving circuit, and simultaneously the 1 st power MOS (M8932) is connected with one end of the 1 st slide rheostat (B1) through the 12 th diode (D12), the 13 th diode (D13), the 6 th resistor (R6), the 120 th capacitor (C120), the 121 th capacitor (C121), the 43 th capacitor (C43), the 153 th resistor (R153), the 43 th capacitor (C43) and the 11 th diode (D11) respectively; the current sensor is connected to an IP-terminal of a1 st current sensor (A1) after being connected to a 9 th toggle switch (W9) through a 123 th capacitor (C123), a 124 th capacitor (C124), a1 st CBB capacitor (CBB 1) and a2 nd CBB capacitor (CBB 2) respectively; the 3 terminal of the 2 nd power MOS (M2) is connected to one end of a 6 th toggle switch (W6), a 7 th toggle switch (W7) and an 8 th toggle switch (W8) through a 102 th resistor (R102), a 103 th resistor (R103) and a 104 th resistor (R104), and the other end of the 6 th toggle switch (W6), the 7 th toggle switch (W7) and the 8 th toggle switch (W8) is connected to the IP-terminal of the 1 st current sensor (A1); the 3 terminal of the 2 nd power MOS (M2) is grounded; the 1 terminal of the 3 rd power MOS (M3) is connected with the G3 terminal of the MOS tube driving circuit; the 2 terminal of the 3 rd power MOS (M3) is connected with the IP + terminal of the 1 st current sensor (A1); the 3 terminal of the 3 rd power MOS (M3) is respectively connected with the S3 terminal of the MOS drive circuit and the 2 terminal of the 4 th power MOS (M4), and is connected to the sampling circuit; the 1 terminal of the 4 th power MOS (M4) is connected with the G4 terminal of the MOS driving circuit; the 3 terminals of the 4 th power MOS (M4) are respectively connected to the S4 terminal of the MOS drive circuit and the 3 terminal of the 2 nd power MOS (M2); the IP-terminal of the 1 st current sensor (A1) is connected to a sampling circuit; the VCC terminal of the 1 st current sensor (A1) is connected to the power supply, and is grounded through the 125 th capacitor (C125); the output VIOUT terminal of the 1 st current sensor (A1) is connected to a sampling circuit after passing through a filter circuit consisting of a 27 th resistor (R27) and a 126 th capacitor (C126).

2. The digital multifunctional power electronic technology teaching experiment platform according to claim 1, characterized in that: the sampling circuit consists of a plurality of paths of current sensors, a voltage sensor and a peripheral circuit, is used for acquiring current signals and voltage signals in the experimental process and sending related signals to the DSP core control board, and comprises a direct current voltage sampling circuit, an alternating current voltage sampling circuit and a current sampling circuit.

3. The digital multifunctional power electronic technology teaching experiment platform according to claim 2, characterized in that: the protection circuit is composed of a comparator circuit and a logic gate circuit, the sampling circuit collects key voltage and current signals of the main circuit, the collected signals are compared with a set value through the comparator circuit, signals of 0 and 1 are output, the signals are sent to the logic gate circuit to be subjected to logic judgment, finally, a judgment result is sent to the DSP core control board, and the DSP core control board processes whether to block PWM output signals or not according to the received judgment result.

4. The digital multifunctional power electronic technology teaching experiment platform according to claim 3, characterized in that: the experimental platform also comprises a power module consisting of an AC-DC power supply assembly, a DC-DC power supply assembly and a DC-DC voltage reduction circuit, wherein the power module is respectively connected with the protection circuit, the sampling circuit, the driving circuit and the DSP core control panel and provides power for the connected circuits.

5. The digital multifunctional power electronic technology teaching experiment platform according to claim 4, characterized in that: the single-phase half-wave controllable rectifying circuit, the single-phase bridge controllable rectifying circuit and the single-phase PWM rectifying circuit are powered by a single-phase alternating current input power supply, and the single-phase alternating current input power supply comprises a transformer, an overcurrent protection circuit and an alternating current voltmeter.

6. The digital multifunctional power electronic technology teaching experiment platform according to claim 5, characterized in that: the Boost circuit, the Buck circuit, the square wave inverter circuit and the SPWM inverter circuit are powered by a single-phase direct-current input power supply, and the single-phase direct-current input power supply comprises an AC/DC switching power supply, an overcurrent protection circuit and a direct-current voltmeter.