阅读说明：本技术 一种低压高频单相逆变电源 (Low-voltage high-frequency single-phase inverter power supply ) 是由 戴训江 王晓彤 林维 于 2021-01-15 设计创作，主要内容包括：本发明公开了一种低压高频单相逆变电源,包括有源钳位电路模块、全桥逆变模块、LC滤波器、有源钳位电路控制器和全桥逆变控制器,所述有源钳位电路模块的输入端作为单相逆变电源的输入端,所述有源钳位电路模块的输出端与所述全桥逆变模块的输入端连接,所述全桥逆变模块的输出端与所述LC滤波器的输入端连接,所述LC滤波器的输出端作为单相逆变电源的输出端；所述有源钳位电路控制器与所述有源钳位电路模块连接,所述有源钳位电路控制器用于控制所述有源钳位电路模块的输出电压恒定；所述全桥逆变控制器用于采用余弦波移相控制算法将所述全桥逆变控制器输入的直流电转换为输出的交流电。本发明逆变电源拓扑结构整体优化,效率和功率密度提升。(The invention discloses a low-voltage high-frequency single-phase inverter power supply, which comprises an active clamping circuit module, a full-bridge inverter module, an LC filter, an active clamping circuit controller and a full-bridge inverter controller, wherein the input end of the active clamping circuit module is used as the input end of the single-phase inverter power supply, the output end of the active clamping circuit module is connected with the input end of the full-bridge inverter module, the output end of the full-bridge inverter module is connected with the input end of the LC filter, and the output end of the LC filter is used as the output end of the single-phase inverter power supply; the active clamping circuit controller is connected with the active clamping circuit module and is used for controlling the output voltage of the active clamping circuit module to be constant; the full-bridge inversion controller is used for converting direct current input by the full-bridge inversion controller into output alternating current by adopting a cosine wave phase-shift control algorithm. The inverter power supply topological structure is integrally optimized, and the efficiency and the power density are improved.)

1. The low-voltage high-frequency single-phase inverter power supply is characterized by comprising an active clamping circuit module, a full-bridge inverter module, an LC filter, an active clamping circuit controller and a full-bridge inverter controller, wherein the input end of the active clamping circuit module is used as the input end of the single-phase inverter power supply, the output end of the active clamping circuit module is connected with the input end of the full-bridge inverter module, the output end of the full-bridge inverter module is connected with the input end of the LC filter, and the output end of the LC filter is used as the output end of the single-phase inverter power supply; the active clamping circuit controller is connected with the active clamping circuit module and is used for controlling the output voltage of the active clamping circuit module to be constant; the full-bridge inversion controller is used for converting direct current input by the full-bridge inversion controller into output alternating current by adopting a cosine wave phase-shift control algorithm.

2. The low-voltage high-frequency single-phase inverter power supply according to claim 1, wherein the active clamp circuit controller is configured to control an output voltage of the active clamp circuit module to be constant, and specifically: the active clamping circuit controller samples the output voltage of the active clamping circuit module, then generates a control signal of the active clamping circuit module according to the sampled output voltage of the active clamping circuit module, and finally controls the output voltage of the active clamping circuit module to be constant according to the generated control signal of the active clamping circuit module.

3. The low-voltage high-frequency single-phase inverter power supply according to claim 1, wherein the expression of the cosine wave phase shift control algorithm is as follows:

in the formula: duty is the inverter bridge drive Duty cycle; m is a modulation degree.

4. The low-voltage high-frequency single-phase inverter power supply according to claim 1, wherein the active clamp circuit controller adopts an analog current PWM controller based on TI LM 5026.

5. The low-voltage high-frequency single-phase inverter power supply according to claim 1, wherein the full-bridge inverter controller adopts a Microchipd sPIC 33-based controller.

6. The low-voltage high-frequency single-phase inverter power supply according to claim 1, wherein the LC filter is a 2-stage LC filter.

Technical Field

The invention belongs to the technical field of inverter power supplies, and particularly relates to a low-voltage high-frequency single-phase inverter power supply.

Background

Customer required input voltage range: 22V-29V, and the output is a 1KHz sine wave of 26 Vrms. The common topological structure of the inverter is that the front end is provided with a direct current boosting isolation and a rear-stage inverter circuit, the boosting isolation generally adopts the topologies of push-pull, forward and active clamping, the rear stage generally adopts high-frequency inverter main circuits such as a half-bridge and a full-bridge, and the like, and finally is provided with a filter circuit, the filter circuit adopts a first-stage LC or a 2-stage LC to eliminate high-frequency switch components, and finally, the difference generates a high-frequency sine wave.

The existing single-phase voltage source inverter VSI-voltage source inverter is a 50Hz/60Hz sine wave power supply with 220V output, and is mainly applied to high-power AC load power supply and UPS.

The prior art adopts a linear power amplifier structure, namely after boosting, resonance is adopted to generate square waves, sine waves are generated through an active filter, and the required waveforms are generated through boosting again. The biggest defects of the technology are multi-level conversion, low efficiency, larger Vthd and larger volume, which are the root causes of the requirements of customers for upgrading.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a low-voltage high-frequency single-phase inverter power supply, which aims to solve the problems.

In order to solve the technical problems, the invention is realized by the following technical scheme:

a low-voltage high-frequency single-phase inverter power supply comprises an active clamping circuit module, a full-bridge inverter module, an LC filter, an active clamping circuit controller and a full-bridge inverter controller, wherein the input end of the active clamping circuit module is used as the input end of the single-phase inverter power supply, the output end of the active clamping circuit module is connected with the input end of the full-bridge inverter module, the output end of the full-bridge inverter module is connected with the input end of the LC filter, and the output end of the LC filter is used as the output end of the single-phase inverter power supply; the active clamping circuit controller is connected with the active clamping circuit module and is used for controlling the output voltage of the active clamping circuit module to be constant; the full-bridge inversion controller is used for converting direct current input by the full-bridge inversion controller into output alternating current by adopting a cosine wave phase-shift control algorithm.

Further, the active clamp circuit controller is configured to control an output voltage of the active clamp circuit module to be constant, specifically: the active clamping circuit controller samples the output voltage of the active clamping circuit module, then generates a control signal of the active clamping circuit module according to the sampled output voltage of the active clamping circuit module, and finally controls the output voltage of the active clamping circuit module to be constant according to the generated control signal of the active clamping circuit module.

Further, the expression of the cosine wave phase shift control algorithm is as follows:

in the formula: duty is the inverter bridge drive Duty cycle; m is a modulation degree.

Further, the active clamp circuit controller adopts an analog current PWM controller based on TI LM 5026.

Further, the full-bridge inverter controller adopts a Microchipd sPIC 33-based controller.

Further, the LC filter is a 2-stage LC filter.

Compared with the prior art, the invention has at least the following beneficial effects: the low-voltage high-frequency single-phase inverter power supply provided by the invention has the advantages that the topology structure of the inverter power supply is integrally optimized, the efficiency and the power density are improved, and the volume is reduced from 130 multiplied by 80 multiplied by 19 to 80 multiplied by 50 multiplied by 14. The cosine wave phase shift control algorithm provided by the invention can meet the requirements of amplitude, frequency and VTHD of output sine waves of customer specifications, further improves the calculation efficiency of a microprocessor, reduces errors generated by duty ratio calculation, further improves the quality and precision of the output sine waves, has the distortion degree of the output sine waves less than 3 percent, and improves the overall performance.

In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a topological structure of a low-voltage high-frequency single-phase inverter power supply according to the present invention;

FIG. 2 is an open loop control output voltage simulation waveform of an active clamp circuit module (active clamp DC-DC converter);

FIG. 3 is a block diagram of a unipolar sine wave PWM control algorithm;

FIG. 4 is a simulation waveform of full-bridge inversion SPWM control built based on Simmetrix;

FIG. 5 is a block diagram of the CPWM algorithm;

FIG. 6 is a simulated waveform of a Simplis-based CPWM control algorithm.

Detailed Description

To make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As a specific embodiment of the present invention, as shown in fig. 1, the low-voltage high-frequency single-phase inverter power supply of the present invention includes an active clamp circuit module, a full-bridge inverter module, an LC filter, an active clamp circuit controller, and a full-bridge inverter controller, wherein an input end of the active clamp circuit module is used as an input end of the single-phase inverter power supply, an output end of the active clamp circuit module is connected to an input end of the full-bridge inverter module, an output end of the full-bridge inverter module is connected to an input end of the LC filter, and an output end of the LC filter is used as an output end of the single-phase inverter.

In the invention, an active clamping circuit controller adopts an analog current PWM controller based on TI LM5026 to boost the input voltage from 22V-29V to 42V-55V, the output voltage of an active clamping circuit module adopts open-loop control, and the input voltage is subjected to feedforward control. The design aims to decouple the control of the active clamp control loop and the control of the inverter circuit, and reduce the influence of the closed-loop control of the active clamp on the post-stage inversion as much as possible. Fig. 2 shows an open-loop control output voltage simulation waveform of an active clamp circuit module (active clamp DC-DC converter), with an input of 24V and an output of 48V.

In the invention, the full-bridge inverter controller adopts a Microchipd sPIC 33-based controller. The LC filter is a 2-stage LC filter.

The inverter circuit adopts a full-bridge structure and an LC filter, can adopt a unipolar SPWM sine wave PWM modulation algorithm to respectively control the output of 2 bridge arms, respectively realizes the output of L and N through symmetrical 2-stage LC filters, and finally differentially outputs a sine wave of 26Vrms1 KHz. A block diagram of a single polarity SPWM sine wave PWM modulation algorithm is shown in fig. 3.

Fig. 4 is a simulation waveform controlled by a full-bridge inversion SPWM built based on simmetrix, where input Vdc is 48V, output Vac is 26Vrms1KHz, a simulation result is Vsin is 26.09, fsin is 1KHz, and Vthd is 1.01%.

The active clamping circuit controller is connected with the active clamping circuit module and used for controlling the output voltage of the active clamping circuit module to be constant, specifically, the active clamping circuit controller samples the output voltage of the active clamping circuit module, then generates a control signal of the active clamping circuit module according to the sampled output voltage of the active clamping circuit module, and finally controls the output voltage of the active clamping circuit module to be constant according to the generated control signal of the active clamping circuit module.

The full-bridge inverter controller is used for converting direct current input by the full-bridge inverter controller into output alternating current by adopting a cosine wave phase-shift control algorithm, and specifically, the expression of the cosine wave phase-shift control algorithm is as follows:

in the formula: duty is the inverter bridge drive Duty cycle; m is a modulation degree.

The basic idea of the CPWM-cosine PWM algorithm is to represent the sine reference waveform of SPWM by cosine, set an initial phase and keep the amplitude unchanged; the carrier wave is a triangular wave with a set frequency, and the modulation of the output amplitude is realized by changing the initially set phase. The block diagram of the CPWM-cosine PWM algorithm (CPWM algorithm for short) is shown in fig. 5.

The mathematical derivation process of the cosine wave phase shift control algorithm (CPWM-cosine PWM algorithm) is as follows:

the L and N single-arm waveforms are represented by cosines:

order:

then: v_{AC_L}-V_{AC_N}＝V_bus·m·M·sin(ωt)

In the formula: v_{AC_L}Outputting an L line for the inverter single phase; v_{AC_N}Outputting N lines for the inverter single phase; v_busIs the direct current input of the inverter circuit; m is a stripe system; m sin is defined in the formula, i.e. the sine of the initial phase angle phi.

Peak of the output sine wave is expressed by vinv.

In the formula: peak ═ V √ 2 √ (V)_{AC_L}-V_{AC_N})

The advancement of the CPWM algorithm is illustrated below, the 4 mos driving of the full-bridge inverter bridge arm is realized by a single chip microcomputer or a DPWM-digital PWM of a DSP, the specific method is to calculate the duty cycle one by one, each sine wave cycle is equally divided into k intervals according to time, each interval calculates the duty cycle, and according to the equal-area algorithm, the ith duty cycle is:

wherein: t is t_i、t_i+1The corresponding time is the i, i +1 th equal part.

The output voltage amplitude is stabilized by adjusting the Duty ratio Duty, i.e. m in the above equation is changed, but the Duty ratio calculation and the quantization error generated after the calculation may affect the quality of the output sine wave. If m is not changed, k duties are all constants, and the value of Duty ratio calculated in advance can be stored in an EPROM and called through a table Lookup-Lookup table.

The input Vin is 48V, the SPWM algorithm shown in fig. 3 is adopted, m is 0.766, and the output voltage is 26Vrms1 KHz; when the input voltage Vin increases to 52V, m is 0.707, and the duty ratio needs to be calculated again in real time, which causes the calculation load of the microprocessor and the calculation error.

If the CPWM algorithm proposed by the present invention is used, the original modulation ratio m is 0.766 and the phase is set to 90 ° when the input is 48V. When the input voltage is 52V, the modulation ratio m is kept unchanged, the phase is changed to arcsin (48/52 × 180/pi) 67 deg., the output voltage is still 26Vrms1KHz, and Vthd is 1%<3 percent. The CPWM algorithm provided by the invention has the advantage that when the input voltage is increased, only calculation needs to be carried out according to the derivationAnd the initial phase of the reference waveform is changed into a calculated value, the sine wave meeting the requirement can be modulated by still adopting a table look-up method without updating the previously calculated duty ratio.

Compared with the SPWM algorithm, the CPWM algorithm reduces the calculation load of the microprocessor, improves the efficiency of the microprocessor, and can meet the requirements of output amplitude and Vthd by adjusting the initial phase of the reference waveform.

FIG. 6 is a simulated waveform of a Simplis-based CPWM algorithm. Input Vin is 52V, m is 0.766, output vinv.rms is 26V, finv is 999Hz, and Vthd is 1.19%.

The invention comprehensively considers the advantages and disadvantages of the circuit topology, finally adopts the front-end active clamping to improve the DC isolation efficiency and the DC bus voltage to be 48V-55V, adopts the full-bridge inversion topology at the rear stage, respectively generates modulated L and N waveforms through each bridge arm, and differentially outputs the required sine wave.

The solution of the invention is that the high-frequency inverter with low-power and low-voltage output, such as a sine wave power supply with 26Vrms1KHz, is mainly applied to the field of special application, such as military power supply.

The invention optimizes the power supply topological structure, adopts an advanced control method to improve the overall efficiency and reduce VTHD, and the calculation and simulation results show that the invention can meet the latest performance index requirements of customers.

The invention provides an optimized topological structure of a low-voltage high-frequency inverter, an active clamping booster circuit adopts open loop control, a full-bridge inverter adopts a novel CPWM-cosine wave phase modulation algorithm (namely the CPWM algorithm), the amplitude of an output sine wave is modulated by adjusting the initial phase of a reference wave, the calculation load of a microprocessor is reduced, and the amplitude, the frequency and the Vthd not only meet higher requirements of customers, but also have better performance.

According to new requirements of customers on the existing low-voltage inverter products, such as voltage total harmonic distortion rate VTHD < 3%, efficiency is improved, size is reduced, and the like, greater challenges are provided for the design requirements of the products. The technical problems solved by the invention are as follows:

the topological structure of the power supply is optimized, and an active clamping voltage boosting circuit is adopted to boost the input direct-current voltage of 22-29V to more than 48V.

Secondly, a main circuit of full-bridge inversion and a 2-stage LC filter circuit are adopted to generate a 26Vrms sine waveform with low Vthd, and the frequency is 1 KHz.

And thirdly, providing a new inversion control algorithm (namely a CPWM algorithm) based on SPWM modulation, respectively controlling the L and N outputs of the 2 bridge arms, and finally differentially outputting the L-N high-frequency sine wave.

Finally, it should be noted that: the above-mentioned embodiments are only specific embodiments of the present invention, which are used for illustrating the technical solutions of the present invention and not for limiting the same, and the protection scope of the present invention is not limited thereto, although the present invention is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: any person skilled in the art can modify or easily conceive the technical solutions described in the foregoing embodiments or equivalent substitutes for some technical features within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the embodiments of the present invention, and they should be construed as being included therein. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.