High-power high-frequency alternating-current power supply with adjustable frequency

Abstract

The invention provides a high-power high-frequency alternating-current power supply with adjustable frequency. The power supply system is powered by 220V commercial power, the 220V commercial power is converted into 360V direct-current voltage through power supply EMI filtering and a PFC module, the 360V direct-current voltage is converted into high-frequency sinusoidal modulation pulses through three groups of independent full-bridge IGBT inverter circuits, the modulation pulses are converted into equivalent sinusoidal voltage output through an LC filter circuit, and then the modulation pulses are converted into three-phase sinusoidal voltage with required amplitude through a transformer to be output. The DSP controller generates an SPWM (sinusoidal pulse width modulation) pulse signal, and the signal is provided for the grid electrode of the IGBT as a switch control voltage through the isolation driving circuit; the three-phase sinusoidal voltage passes through a sampling circuit and then is converted into a direct-current voltage signal by an isolation voltage sensor and a current sensor, the direct-current voltage signal is fed back to an A / D (analog / digital) of a DSP (digital signal processor) for sampling calculation, and the duty ratio of an SPWM modulation pulse is adjusted; and the DSP controller realizes keyboard input and display functions. The ground test of the power converter on the supersonic cruise missile and the hypersonic cruise missile is realized.

Description

Technical Field

[0001] The invention relates to the technical field of power electronics, and in particular to a high-power high-frequency AC power supply with adjustable frequency. Background Art

[0002] The onboard power converter is responsible for converting the three-phase AC voltage generated by the missile generator into DC voltage to supply power to the entire missile. Therefore, as a key component of onboard power conversion, the power converter needs to be fully tested for its performance. When the power converter is tested on the ground, it is unrealistic to use the onboard generator to power it. Therefore, a dedicated power supply is needed to simulate the three-phase or six-phase AC generated by the onboard generator to test the power converter. In the past, the onboard generator usually generated 400Hz medium-frequency AC power. However, with the rapid development of supersonic cruise missiles and hypersonic cruise missiles, the speed of the onboard generator has gradually increased, and the frequency fluctuates between 2kHz and 4kHz. The highest AC frequency of 4kHz is 10 times that of the traditional 400Hz medium-frequency power supply. The greatly increased frequency requires a significant increase in the switching frequency of the inverter link, which leads to higher switching losses. At the same time, the high-frequency noise generated brings a more severe electromagnetic environment, which puts higher requirements on the circuit design. The traditional fixed 400Hz medium-frequency AC power supply cannot meet the new test requirements, and a higher frequency AC power supply is required to achieve this. There are currently no similar products on the market. Summary of the invention

[0003] The purpose of the present invention is to provide a high-power high-frequency AC power supply with adjustable frequency to realize ground testing of power converters on supersonic cruise missiles and hypersonic cruise missiles.

[0004] The power supply system of the present invention is powered by 220V mains electricity, which is converted into 360V DC voltage through power supply EMI filtering and PFC module, and then converted into high-frequency sinusoidal modulation pulses through three independent full-bridge IGBT inverter circuits. The modulation pulses are converted into equivalent sinusoidal voltage outputs through LC filtering circuits, and then converted into three-phase sinusoidal voltage outputs with required amplitudes through transformers; a DSP controller generates an SPWM modulation pulse signal, which is provided to the gate of the IGBT as a switch control voltage through an isolation drive circuit; the three-phase sinusoidal voltage is converted into a DC voltage signal by an isolation voltage and current sensor after passing through a sampling circuit, and fed back to the A / D of the DSP for sampling calculation to adjust the duty cycle of the SPWM modulation pulse; and the DSP controller realizes keyboard input and display functions.

[0005] Beneficial effects:

[0006] The power supply provides a high-power multi-phase AC voltage with adjustable frequency to the power converter under test, simulating the missile environment to test whether the power converter can work normally under this condition. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0008] Figure 1 It is a schematic diagram of the present invention.

[0009] Figure 2 This is the inverter circuit principle intention of the present invention.

[0010] Figure 3 It is the principle diagram of the driving circuit of the present invention.

[0011] Figure 4 It is the principle diagram of the PWM pulse output circuit of the present invention.

[0012] Figure 5 It is the principle diagram of the A / D conversion circuit of the present invention.

[0013] Figure 6 It is the principle diagram of the keyboard scanning circuit of the present invention.

[0014] Figure 7 It is the principle diagram of the serial communication circuit of the present invention.

[0015] Figure 8 It is the principle diagram of the alarm monitoring circuit of the present invention. DETAILED DESCRIPTION

[0016] Embodiments of the present invention are described below with reference to the accompanying drawings. Elements and features described in one drawing or one embodiment of the present invention may be combined with elements and features shown in one or more other drawings or embodiments. It should be noted that for the purpose of clarity, the representation and description of components and processes that are not related to the present invention and are known to those of ordinary skill in the art are omitted in the drawings and descriptions.

[0017] This embodiment provides a high-frequency AC power supply with adjustable frequency, which can output a three-phase sinusoidal AC signal with a continuously adjustable frequency of 2kHz to 4kHz, a phase difference of 120° for each phase, an adjustable line voltage of 25V (rated) and 17 to 30V, and an output power of up to 3kW.

[0018] 1. Structure

[0019] like Figure 1As shown, its working principle is as follows: the power supply system is powered by ~220V AC power. After power supply EMI filtering (electromagnetic interference filter, grid filter, grid noise filter), the 220V voltage is converted into 360V DC voltage by PFC (Power Factor Correction) modules. This DC voltage is then converted into high-frequency sinusoidal modulated pulses through three independent full-bridge IGBT (Insulated Gate Bipolar Transistor) inverter circuits. This modulated pulse is converted into an equivalent sinusoidal voltage output through an LC filtering circuit, and then converted into a three-phase sinusoidal voltage output with the required amplitude through a transformer. The DSP controller generates an SPWM (sinusoidal pulse width modulation) sinusoidal modulated pulse signal, which is provided to the gate of the IGBT as a switch control voltage through an isolated drive circuit, and the frequency is adjusted by adjusting the carrier frequency of the sinusoidal modulated pulse; the final output voltage is converted into a DC voltage signal by the isolated voltage and current sensor after passing through a sampling circuit, and fed back to the A / D of the DSP (digital signal processing) for sampling and calculation, so as to adjust the duty cycle of the SPWM modulated pulse to stabilize the output voltage, and realize overvoltage and overcurrent protection functions at the same time; in addition, the DSP controller realizes keyboard input and display functions.

[0020] 2. Inverter Circuit

[0021] The inverter circuit schematic diagram of this embodiment is as follows Figure 2 As shown, it is used to chop the DC voltage into high-frequency modulated pulses. The three-phase independent full-bridge inverter circuit is composed of three single-phase inverters connected in star shape, which can realize single-phase and three-phase four-wire power supply at the same time. Although this circuit structure has many components and high cost, it is easy to realize modular structure, online hot replacement, and N+1 module redundancy technology because each phase can be controlled independently. Therefore, the system has high reliability and strong unbalanced load capacity. G1~G4 are IGBT modules that chop the DC voltage into high-frequency DC pulses under the control of SPWM signals; V1~V4 are freewheeling diodes, which provide freewheeling for inductive loads when the IGBT is turned off; C1~C4 are absorption capacitors, which are used to reduce the voltage change rate when the IGBT is turned off to reduce the switching loss of the IGBT; R1~R4 are current limiting resistors, which limit the discharge current of the absorption capacitor when the IGBT is turned on. At the same time, in order not to affect the effect of the absorption capacitor charging, diodes VT1~VT4 are connected in parallel at both ends of the current limiting resistor.

[0022] 3. Driving circuit

[0023] The driving circuit schematic diagram of this embodiment is as follows Figure 3As shown, it is used to amplify and isolate the PWM control signal. U1 and U2 are two SKYPER32R driver modules, which provide 4 drive signals to drive the 4 IGBTs of the inverter bridge. Taking U1 as an example, the power input of the SKYPER32R driver module is 15V and is located on the input side, which is completely isolated from the high-voltage side.

[0024] T1+ and T1- are two PWM modulation signals generated by the control circuit and connected to the TOP_IN and BOT_IN of the module. The two capacitors C108 and C109 are used to suppress the high-frequency noise contained in the input signal.

[0025] nERROR_OUT is the fault output pin. When a fault occurs, this pin will be pulled high and the output signal will be blocked to keep the IGBT in the off state. When the fault is removed and TOP_IN and BOT_IN are set to a low level for more than 9us, this pin will be reset. This pin is an open collector output, so an external pull-up resistor R109 is required. The selection range of this resistor is , where is the current output capacity of this pin, so this resistor range is 1kΩ~10kΩ, and 4.7kΩ is selected here.

[0026] nERROR_IN is the external shutdown signal input pin. When this pin is pulled low, the module generates a fault signal, blocks the output, and nERROR_OUT is pulled high. This pin is internally pulled up to 5V, and no external pull-up resistor is required. The ERRI signal comes from the control circuit. After passing through transistor Q101, the control is reversed. When the ERRI signal is high, a fault signal is generated.

[0027] H1 and L1 are control signals for driving the upper and lower bridge arms of the inverter bridge. R101 to R104 are gate resistors. The selection of these four resistors has a certain influence on the switching speed. The smaller the resistance, the faster the switching response speed, but it will increase the switching loss. The resistance of this resistor is generally 3Ω to 22Ω, and the power is 1W. Here, 22Ω is selected. R107 and R108 are connected between the gate and emitter of the IGBT to ensure that the IGBT can be reliably turned off.

[0028] D101, R107, C105 and D102, R108, C106 respectively constitute the peripheral circuit of the dynamic short-circuit protection of the upper and lower outputs. D101 and D102 are connected to the emitter of the IGBT to block the high voltage during the IGBT shutdown period. Its reverse withstand voltage should be higher than that of the IGBT, and its reverse recovery time should be lower than the rise time of the IGBT collector-emitter voltage Vce. The parameters of R107, C105 and R108, C106 determine the blanking time of the short-circuit protection startup.

[0029] 4. Control circuit

[0030] The control circuit is used to generate SPWM control signals to realize control flow, network protocol, data processing, bus interface logic conversion, AD circuit control, buttons and display functions.

[0031] In the design of the control circuit, TI's C2000 series DSP controller TMS320LF2407A is used as the core processor to realize a total of 12 PWM control pulses and 6 A / D conversions. A serial communication interface SCI module is used for serial display control.

[0032] In order to realize key input, alarm monitoring, status judgment and other logical functions, a CPLD is also required to cooperate with the DSP. Here, the CPLD uses ALTRA's EPM7160STI, which contains enough logic units and I / Os to meet the needs.

[0033] like Figure 4 As shown in the figure, LF2407A provides two powerful event manager modules, each module contains 6 independent PWM pulse width modulation channels, which can easily realize symmetrical and asymmetrical waveforms of PWM. Among them, PWM1~PWM12 are 12 PWM signals generated by DSP, which are converted into 5V level through bus buffer 54HC16245 and output to PWM output socket to drive the corresponding inverter bridge arm. J8~J10 are the output sockets connected to the three-phase power circuit respectively.

[0034] A / D conversion circuit such as Figure 5 As shown in the figure, LF2407A includes 16 channels of A / D converter, with a conversion bit number of 10 bits and a minimum conversion rate of 500ns. In this solution, 6 channels are selected to collect three-phase voltage and current signals.

[0035] The measured signal first passes through the voltage follower composed of operational amplifiers (N1~N6) to increase the input impedance of the circuit. Then it passes through the current limiting resistors (R200~R206) and enters the A / D acquisition channel. The diodes (D100~D106, D200~D206) together with the current limiting resistors form a clamping circuit to limit the input voltage within the VCC range to protect the A / D channel. C300~C306 are filter capacitors.

[0036] In addition, the voltage reference source ADR03 (U14) provides a reference voltage for A / D conversion. The output voltage of this reference source is 2.5V, the basic accuracy is 0.1%, and the temperature stability is 3ppm / ℃, which is sufficient to meet the needs. In order to improve the A / D measurement accuracy and improve the anti-interference ability, the A / D power supply VCCA is separated from the digital power supply voltage VCC through an inductor (L103), and the A / D power ground is separated from the digital ground GND through a 0 ohm resistor (R134). The keyboard scanning circuit is as follows Figure 5As shown in the figure, RL0~RL7 and CL0~CL7 are the row and column lines of the scan matrix respectively, J5 is the keyboard interface, the resistor row RP1 is the current limiting resistor of the row line, XINT1 is the DSP external interrupt interface, and D0~D7 are the lower 8 bits of the DSP data line, all of which are connected to the CPLD. After a key is pressed, the CPLD sends an interrupt signal to the DSP, and the DSP reads the key value of the key through the data line. In addition, the control signal of LED0~LED5 as the indicator light is provided by the CPLD.

[0037] Serial communication circuits such as Figure 7 As shown, the DSP's four general IO ports IOPC0~IOPC3 are connected to the CPLD for status judgment. The J6 socket is the standard interface of the Devin display, where pin 4 is the data sending pin, and pins 5 and 6 receive data, which are respectively connected to the receiving and sending of the serial communication interface. Pin 3 is the buffer full indication signal connected to the CPLD for judgment.

[0038] Alarm monitoring circuit such as Figure 8 As shown, in this embodiment, the monitoring and alarm of output overvoltage and overcurrent are realized by collecting the feedback signal value through the A / D channel of DSP. In addition, there are monitoring and alarm of the inverter module and the PFC power factor correction module, which are completed by CPLD in cooperation with DSP. J8~J10 are three groups of output control interfaces connected to the power circuit respectively. Except for the PWM output signal, all other control signals are connected to CPLD. The DSP external interrupt XINT2 is connected to CPLD, where PFC-Ctrl is the PFC external control signal, and when it is high level, the output of PFC is turned off; PFC-Warn is the PFC fault alarm signal, when this signal is high level, it indicates PFC fault, at this time CPLD sends an interrupt signal to DSP, DSP reads the error code at this time through the data line, turns off the corresponding output, and displays the fault location on the display; ERR1 and ERR2 are the fault alarm signals of the inverter circuit, when it is high level, it indicates the inverter circuit fault, and the working process is the same as the PFC alarm signal; SD1 is the external shutdown signal of the inverter circuit, and when it is high level, the output of the inverter circuit will be cut off. In addition, the speaker (SP200) and its peripheral circuits constitute a sound alarm circuit, which is controlled by the CPLD and acts as a sound alarm when a fault signal is generated.

[0039] Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and conversions can be made without exceeding the spirit and scope of the present invention defined by the appended claims. Moreover, the scope of the present application is not limited to the specific embodiments of the process, equipment, means, method and steps described in the specification. It will be easily understood by those of ordinary skill in the art from the disclosure of the present invention that the process, equipment, means, method or step that performs the function substantially the same as the corresponding embodiment described herein or obtains the result substantially the same as the corresponding embodiment described herein, existing and future to be developed can be used according to the present invention. Therefore, the appended claims are intended to include such processes, equipment, means, methods or steps within their scope.

Claims

1. A high-power, high-frequency AC power source with adjustable frequency, characterized in that The power supply system is powered by ~220V mains electricity, which is converted into 360V DC voltage through power EMI filtering and PFC module, and then converted into high-frequency sinusoidal modulated pulses through three independent full-bridge IGBT inverter circuits. This modulated pulse is converted into an equivalent sinusoidal voltage output through an LC filter circuit, and then converted into a three-phase sinusoidal voltage output with the required amplitude through a transformer; The DSP controller generates an SPWM modulated pulse signal, which is provided to the gate of the IGBT as a switch control voltage through the isolation drive circuit; the three-phase sinusoidal voltage is converted into a DC voltage signal by the isolation voltage and current sensor after passing through the sampling circuit, and fed back to the DSP's A / D for sampling calculation to adjust the duty cycle of the SPWM modulated pulse; the DSP controller also realizes keyboard input and display functions.

2. A frequency-adjustable high-power high-frequency AC power source as claimed in claim 1, characterized in that The full-bridge IGBT inverter circuit is composed of three single-phase inverters connected in star connection.

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