Intermediate frequency power supply of inversion scheme

Abstract

The utility model discloses an intermediate frequency power supply of an inversion scheme, which relates to the technical field of automation control, and comprises a control unit, an alternating current rectification unit, a direct current inversion unit, an alternating current rectification unit, a direct current inversion unit, a direct current rectification unit, a direct current rectification unit and a direct current inversion unit, the control unit is used for controlling the alternating-current rectification unit and providing stable direct-current voltage for the direct-current inversion unit, the direct-current inversion unit converts direct current input by the alternating-current rectification unit into intermediate-frequency alternating current, the working state of the power supply is monitored in real time through a plurality of detection circuits in the control unit, and a starting strategy is adjusted in time through an auxiliary control circuit and other circuits. The temperature detection circuit helps to monitor the temperature rise condition of the medium-frequency power supply, and the temperature in the working environment is reasonably controlled to prevent the temperature drift from affecting the starting of the oscillation circuit.

Description

TECHNICAL FIELD

[0001] The utility model relates to the automation control technical field, concretely relates to a medium frequency power supply of inverter scheme. BACKGROUND

[0002] Three standardization, modularization and intelligentization medium frequency power supply board usually refers to the application of three standardization, modularization and intelligentization technology in medium frequency power supply design. With the promotion of industrial automation, medium frequency power supply is widely used in the fields of electric power, metallurgy and chemical industry. The design background of three standardization, modularization and intelligentization power supply board is to improve the stability, efficiency and adaptability of power supply system. Standardization helps to reduce manufacturing cost and maintenance difficulty, modularization makes system configuration and expansion more flexible, and intelligentization improves energy efficiency and safety through automatic adjustment and monitoring function. The application of three standardization, modularization and intelligentization power supply board not only improves the overall efficiency of the industrial chain, but also promotes the realization of energy saving and emission reduction target.

[0003] The traditional venturi bridge circuit is also a kind of implementation scheme of medium frequency power supply, but the venturi bridge circuit scheme has poor load carrying capacity, is easily affected by temperature to cause the oscillation circuit to fail to start, and the output waveform is easy to distort, and the conversion efficiency of the power supply board is low, and the temperature rise is large, so an inverter scheme medium frequency power supply is needed to solve the above problems and realize nationalization. UTILITY MODEL CONTENT

[0004] To solve the above technical problems, a medium frequency power supply of inverter scheme is provided, which solves the problems of poor load carrying capacity of the venturi bridge scheme medium frequency power supply board, easy to be affected by temperature to cause the oscillation circuit to fail to start, easy to distort the output waveform, low conversion efficiency of the power supply board and large temperature rise.

[0005] To achieve the above purposes, the utility model adopts the technical scheme that:

[0006] A medium frequency power supply of inverter scheme comprises:

[0007] A control unit monitors and controls the AC rectifier unit and the DC inverter unit;

[0008] An AC rectifier unit rectifies the input AC power supply into DC power and provides stable DC voltage to the DC inverter unit;

[0009] A DC inverter unit converts the DC power input by the AC rectifier unit into medium frequency AC power;

[0010] The direct current inverting unit is composed of an inverting single-chip microcomputer, an isolation circuit, an SPWM driving circuit and a single-phase full-bridge SPWM inverting circuit, the single-phase full-bridge SPWM inverting circuit comprises four switching tubes, the inverting single-chip microcomputer calculates the duty ratio of each switching tube in each carrier frequency through a timer and outputs a pulse signal of the duty ratio, and the isolation circuit is composed of a 4-channel digital isolator.

[0011] In an optional embodiment, the alternating current rectifying unit is composed of an input filter circuit, a protection circuit, an AC-DC circuit and an auxiliary circuit, and external alternating current input is used to power the AC-DC circuit and the auxiliary circuit after passing through the input filter circuit and the protection circuit.

[0012] In an optional embodiment, the input end of the input filter circuit is provided with a pressure-sensitive resistor R73 and a transient absorption diode D2.

[0013] In an optional embodiment, the bridge arm midpoints of the single-phase full-bridge SPWM inverting circuit are connected with a load, and the output voltage is a pulse waveform with an amplitude of Vdc.

[0014] In an optional embodiment, the control unit comprises an auxiliary control circuit and a detection circuit, the auxiliary control circuit comprises a control chip U3, and the detection circuit is composed of a temperature detector, a voltage detection circuit and a current detection circuit.

[0015] In an optional embodiment, the voltage detection circuit is composed of a high-reliability isolation voltage sampling amplifier, a digital isolator and an operational amplifier amplification circuit.

[0016] In an optional embodiment, the current detection circuit is provided with an internal isolation current sensor, which converts a current signal into a voltage signal and then performs AD conversion.

[0017] Compared with the prior art, the utility model has the beneficial effects that:

[0018] In the intermediate frequency power supply of the inverting scheme, the working state of the power supply is monitored in real time through multiple detection circuits in the control unit, and the starting strategy is adjusted in time through the auxiliary control circuit and other circuits to avoid the starting failure problem caused by unstable current or excessively high temperature, the temperature detection circuit helps to monitor the temperature rise of the intermediate frequency power supply, and the temperature in the working environment is controlled reasonably to prevent the temperature drift from affecting the starting of the oscillation circuit.

[0019] The inverter scheme's intermediate frequency power supply provided by the scheme realizes effective electrical isolation of the power circuit and the control circuit by using isolation circuits, such as digital isolator NSI8940 and NSi1311-DSWR high-reliability isolation voltage sampling amplifier, reduces the influence of electromagnetic interference on the oscillation circuit, and thus improves the stability and starting reliability of the oscillation circuit at different working temperatures;

[0020] The inverter scheme's intermediate frequency power supply provided by the scheme can maintain stable control signals when high-power switches work, prevents temperature drift and the failure of the oscillation circuit to start due to interference, simultaneously adjusts the system temperature to prevent overheating by real-time temperature monitoring and feedback, further optimizes the heat dissipation design of the power board, and reduces the temperature rise of the intermediate frequency power board. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The system composition of the inverter scheme's intermediate frequency power supply provided by the utility model is provided;

[0022] Figure 2 The schematic diagram of the direct current inversion unit in the utility model is provided;

[0023] Figure 3 The principle block diagram of the isolation driving circuit in the utility model is provided;

[0024] Figure 4 The circuit principle diagram of the isolation driving circuit in the utility model is provided;

[0025] Figure 5 The circuit principle diagram of the alternating current rectification unit in the utility model is provided;

[0026] Figure 6 The circuit principle diagram of the control chip of the control unit of the utility model is provided;

[0027] Figure 7 The circuit principle diagram of the voltage detection circuit of the utility model is provided;

[0028] Figure 8 The circuit principle diagram of the current detection circuit of the utility model is provided;

[0029] Figure 9 The working principle diagram of the inverter scheme's intermediate frequency power supply provided by the utility model is provided. DETAILED DESCRIPTION

[0030] The following description is used to disclose the utility model so that those skilled in the art can realize the utility model. The preferred embodiments in the following description are only as examples, and other obvious variants can be thought of by those skilled in the art.

[0031] Referring to Figure 1 - Figure 8 As shown in the figure, an intermediate frequency power supply of an inverter scheme comprises:

[0032] A control unit, which monitors and controls the AC rectification unit and the DC inversion unit;

[0033] An AC rectification unit, which rectifies the input AC power supply into DC power and provides stable DC voltage to the DC inversion unit;

[0034] A DC inversion unit, which converts the DC power input by the AC rectification unit into intermediate frequency AC power;

[0035] The DC inversion unit is composed of an inverter single-chip microcomputer, an isolation circuit, an SPWM drive circuit and a single-phase full-bridge SPWM inverter circuit, the single-phase full-bridge SPWM inverter circuit includes four switching tubes, the inverter single-chip microcomputer calculates the duty ratio of each switching tube within each carrier frequency through a timer and outputs a pulse signal of the duty ratio, and the isolation circuit is composed of a 4-channel digital isolator.

[0036] Specifically, the AC rectification unit realizes power factor correction, AC-DC conversion and provides DC bus voltage, the DC inversion unit realizes DC-AC conversion and outputs single-phase AC intermediate frequency voltage, and the control unit is responsible for intelligent control of each module, inverter algorithm and drive control, state parameter detection, inverter drive control and other functions.

[0037] Further, the AC rectification unit is composed of an input filter circuit, a protection circuit, an AC-DC circuit and an auxiliary circuit, and the external AC input is powered to the AC-DC circuit and the auxiliary circuit after passing through the input filter circuit and the protection circuit.

[0038] Further, the input end of the input filter circuit is provided with a pressure-sensitive resistor R73 and a transient absorption diode D2 for suppressing external transient interference and transient peak test during electromagnetic compatibility test.

[0039] Further, the load is connected between the bridge arm midpoints of the single-phase full-bridge SPWM inverter circuit, and the output voltage is a pulse waveform with an amplitude of Vdc.

[0040] Referring to Figure 3 and Figure 4As shown, ED2113D is a full-bridge driving chip of single-phase full-bridge SPWM inverter circuit, which integrates logic signal input processing circuit, dead zone timing control circuit, blocking circuit, level shift circuit, pulse filter circuit and output driving circuit inside. The chip has blocking function to prevent simultaneous conduction of output power tubes. EG2113D adopts bootstrap suspension driving power supply structure, which greatly simplifies the design of driving power supply, and only one power voltage can complete the driving of two power switching devices. The single-chip microcomputer as the main control chip calculates the duty ratio of each switching tube in each carrier frequency through the timer, and outputs the pulse signal of the duty ratio. In order to realize isolation design, 4-channel digital isolator NSI8940 is selected, which is an integrated isolation type four-channel digital isolator with data rate up to 150Mbps, and provides 5V to 5V, 5V to 3.3V, 3.3V to 5V conversion mode. By using the digital isolator, the MCU main control auxiliary circuit and the power part form effective electrical isolation, reducing the interference between each other.

[0041] Further, the control unit includes an auxiliary control circuit and a detection circuit, the auxiliary control circuit includes a control chip U3, and the detection circuit is composed of a temperature detector, a voltage detection circuit and a current detection circuit.

[0042] Specifically, the auxiliary control circuit in the control unit is designed to be fully isolated, and various isolated auxiliary power supplies and chip devices are used to isolate the driving circuit, the sampling circuit and the AC output circuit, thereby reducing the disturbance of the power circuit to the control circuit, ensuring the accuracy of the feedback circuit and enhancing the stability of the SPWM control.

[0043] Further, the voltage detection circuit is composed of a high-reliability isolated voltage sampling amplifier, a digital isolator and an operational amplifier amplification circuit.

[0044] Further, the current detection circuit is built-in with an isolated current sensor, which converts the current signal into a voltage signal and then performs AD conversion.

[0045] Specifically, the control unit is responsible for voltage, current and temperature state detection, power-on control, slot recognition, IIC communication, SPWM modulation waveform control, SPWM driving and other functions.

[0046] Referring to Figure 7As shown, the voltage detection circuit utilizes a high-reliability isolated voltage sampling amplifier, a digital isolator and an operational amplifier to design the voltage monitoring circuit, wherein the voltage sampling amplifier adopts NSi1311-DSWR, which is a high-performance isolated amplifier, the single-ended input signal range is 0.1V to 2V, the fixed gain is 1, and differential analog output is provided, low offset and gain drift ensure the accuracy in the whole temperature range, and high common-mode transient immunity can ensure that the chip can provide accurate and reliable measurement results even in the presence of high-power switches.

[0047] Referring to Figure 8 As shown, the current detection adopts an isolated current sensor to convert the current signal into a voltage signal and then perform AD conversion.

[0048] Working principle and implementation: the external AC input is supplied to the AC-DC circuit and auxiliary circuit after passing through the input filter circuit and protection circuit of the AC rectifier unit, the auxiliary power supply of the auxiliary circuit is powered on and outputs, and after the auxiliary power supply normally outputs, the control unit starts to work, the control unit detects the external input address signal and enable, disable, reset and other signals, the IIC interface communicates with other devices on the bus, receives the information sent by the external unit, and sends the state information (output voltage, current, temperature, etc.) of itself.

[0049] The above shows and describes the basic principle, main features and advantages of the present application. It should be understood by those skilled in the art that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the present application. The scope of protection required by the present application is defined by the appended claims and their equivalents.

Claims

1. An intermediate frequency power supply of an inverter scheme, characterized by comprising: The utility model relates to a kind of AC-DC conversion device, including: Control unit, which monitors and controls AC rectifier unit and DC inverter unit; AC rectifier unit, which rectifies input AC power into DC and provides stable DC voltage to DC inverter unit; DC inverter unit, which converts DC input by AC rectifier unit into intermediate frequency AC; Wherein, the DC inverter unit is composed of inverter single-chip microcomputer, isolation circuit, SPWM drive circuit and single-phase full-bridge SPWM inverter circuit, the single-phase full-bridge SPWM inverter circuit includes four switching tubes, the inverter single-chip microcomputer calculates the duty ratio of each switching tube within each carrier frequency through timer, and outputs the pulse signal of the duty ratio, the isolation circuit is composed of 4-channel digital isolator.

2. The intermediate frequency power supply of claim 1, wherein: The AC rectifier unit is composed of input filter circuit, protection circuit, AC-DC circuit and auxiliary circuit, and the external AC input is powered to AC-DC circuit and auxiliary circuit after passing through input filter circuit and protection circuit.

3. The intermediate frequency power supply of claim 2, wherein: The input end of the input filter circuit is provided with a pressure-sensitive resistor R73 and a transient absorption diode D2.

4. The intermediate frequency power supply of claim 1, wherein: The bridge arm midpoint of the single-phase full-bridge SPWM inverter circuit is connected with a load, and the output voltage is a pulse waveform with amplitude Vdc.

5. The intermediate frequency power supply of claim 1, wherein: The control unit includes an auxiliary control circuit and a detection circuit, the auxiliary control circuit includes a control chip U3, and the detection circuit is composed of a temperature detector, a voltage detection circuit and a current detection circuit.

6. The intermediate frequency power supply of claim 5, wherein: The voltage detection circuit is composed of a high-reliability isolation voltage sampling amplifier, a digital isolator and an operational amplifier amplification circuit.

7. The medium frequency power supply of claim 5, wherein: The current detection circuit is built-in with an isolation current sensor, which converts the current signal into a voltage signal and then performs AD conversion.

Images