CN101267167A - Boost High Frequency Link Inverter - Google Patents

Abstract

The invention relates to a step-up high-frequency chain inverter, the circuit structure of which is sequentially cascaded by an input filter circuit, an energy storage inductor, a high-frequency inverter, a high-frequency transformer, a cycle converter, and an output filter circuit, and Between the output load and the input DC power supply is connected a high-frequency electrical isolation flyback converter energy feedback circuit composed of a cycle converter, a high-frequency energy storage transformer, and a rectifier cascaded in sequence, which can convert an unstable The DC voltage is converted into the required stable high-quality sinusoidal AC voltage, with high-frequency electrical isolation, strong output and input voltage matching ability, bidirectional power flow, high conversion efficiency, small size, light weight, small input current ripple, and load adaptability The advantages of strong capability, low audio noise, high reliability when the load is short-circuited, low cost, large output capacity, and wide application prospects have laid the key technology for new large-capacity inverter power supplies and static converters.

Description

Boost High Frequency Link Inverter

technical field

The boost type high-frequency chain inverter involved in the present invention belongs to the power electronic conversion technology.

Background technique

Buck (Forward), Boost (single-ended Boost) and Buck-Boost (Flyback) are the three most basic and commonly used converter types, and their performance is shown in Table 1. Table 1 fully shows that although the Buck (Forward) converter has a large output capacity, it has defects such as large input current ripple and low reliability of the converter when the load is short-circuited; although the Buck-Boost (Flyback) converter has The converter has high reliability, but has defects such as large input current ripple and small output capacity; Boost (single-ended Boost) converter has the advantages of small input current ripple, high reliability when the load is short-circuited, and large output capacity. Buck (Forward) and Buck-Boost (Flyback) converters have large input current fluctuations, and their high-order harmonic currents will not only interfere with surrounding electronic equipment in the form of conduction and radiation, but also generate distorted power and reduce conversion efficiency; while Boost (Single-ended Boost) The energy storage inductance of the converter is located on the input side, the input current has small pulsation, the EMI to the power supply is small, and the current on the input side is easy to control.

Table 1 Performance comparison of Buck (Forward), Boost (single-ended Boost), and Buck-Boost (Flyback) converters

Therefore, the Boost (single-ended Boost) converter has the advantages of both Buck (Forward) and Buck-Boost (Flyback), that is, small input current ripple, high reliability when the load is short-circuited, and large output capacity. The power conversion occasions with small current ripple, high reliability when the load is short-circuited, and large-capacity output have significant advantages and an important position.

High-frequency link inverter technology refers to the DC-AC conversion technology with high-frequency electrical isolation (above 20kHz) between the output AC load and the input DC power supply. An effective way to improve safety, reliability and electromagnetic compatibility. Power electronics researchers have achieved remarkable research results in the research of Buck and Buck-Boost type converters. However, people's research on Boost converters is mainly limited to DC-DC conversion (such as "A soft-switching active-clamp scheme for isolated full-bridge boost converter" proposed by En-Sung Park et al., IEEE APEC, 2004, pp .1067～1070.) and AC-DC conversion (such as "Novel current-loop feed-forward compensation for boostPFC converter" proposed by Manjing Xie et al., IEEE APEC, 2004, pp.750～755.), for Boost type high frequency chain The research on DC-AC conversion technology has not yet been seen.

The above discussion shows that the Boost converter has demonstrated its advantages and played an important role in the field of DC-DC and AC-DC power conversion. How to make full use of the advantages of the Boost converter to realize and improve the performance of the DC-AC power conversion system is a topic worthy of further research and exploration. Therefore, it is imminent to seek a new type of high-frequency link inverter with small input current ripple, high reliability when the load is short-circuited, and large output capacity.

Contents of the invention

The purpose of the present invention is to provide a high-frequency electrical isolation between the output AC load and the input DC power supply, strong output and input voltage matching ability, bidirectional power flow, small size, light weight, high conversion efficiency, small input current ripple, A step-up high-frequency link inverter with significant advantages such as low audio noise, high reliability when the load is short-circuited, low cost, large output capacity, and wide application prospects.

The boost (Boost) type high-frequency chain inverter of the present invention is composed of an input filter circuit, an energy storage inductor, a high-frequency inverter, a high-frequency transformer, a cycloconverter, and an output filter circuit in cascaded order, and the output load A high-frequency electrical isolation flyback converter energy feedback circuit is connected between the input DC power supply, and the high-frequency electrical isolation flyback converter energy feedback circuit is composed of a cycloconverter, a high-frequency energy storage transformer, and a rectifier according to Sequential cascaded structure, the input end of the cycloconverter is connected with the output load, and the output end of the rectifier is connected with the input DC power supply.

The technical solution of the present invention is to give full play to the advantages of the Boost converter to realize and improve the performance of the DC-AC power conversion system, and propose a new concept, circuit structure and topology family of the boost (Boost) high-frequency link inverter for the first time.

The boost (Boost) type high-frequency chain inverter of the present invention can convert an unstable DC voltage into a high-quality stable sinusoidal AC voltage with a required voltage, and has high-frequency electrical isolation and strong output and input voltage matching capabilities. , two-way power flow, high conversion efficiency, small size, light weight, small input current ripple, strong load adaptability, low audio noise, high reliability when the load is short-circuited, low cost, large output capacity, and wide application prospects. The boost (Boost) high-frequency link inverter fully demonstrates the advantages of the Boost converter, and realizes and improves the performance of the DC-AC power conversion system.

Description of drawings

Fig. 1 is a circuit structure diagram of a boost (Boost) type high-frequency link inverter of the present invention.

Figure 2 is a schematic waveform diagram of a boost (Boost) type high-frequency link inverter.

FIG. 3 is a schematic diagram of a push-pull full-wave circuit of the first example of a boost (Boost) high-frequency link inverter circuit in the present invention.

Fig. 4 is a schematic diagram of a second example of a boost (Boost) high-frequency chain inverter circuit of the present invention—a push-pull bridge circuit.

Fig. 5 is a circuit schematic diagram of the third example of a boost (Boost) type high-frequency chain inverter circuit of the present invention - a half-bridge full-wave circuit.

FIG. 6 is a schematic diagram of a half-bridge circuit of the fourth example of a boost (Boost) high-frequency chain inverter circuit in the present invention.

Fig. 7 is a circuit schematic diagram of a full-bridge full-wave circuit in Example 5 of the boost (Boost) high-frequency chain inverter circuit of the present invention.

Fig. 8 is a schematic diagram of a full-bridge bridge circuit example six of the boost (Boost) high-frequency chain inverter circuit of the present invention.

Fig. 9 is a block diagram of voltage instantaneous value feedback control of a boost (Boost) high-frequency link inverter of the present invention.

Fig. 10 is a waveform diagram of the principle of voltage instantaneous value feedback control.

Detailed ways

The boost (Boost) type high-frequency chain inverter circuit structure of the present invention is composed of an input filter circuit, an energy storage inductor, a high-frequency inverter, a high-frequency transformer, a cycloconverter, and an output filter circuit connected in sequence, and A high-frequency electrical isolation flyback converter energy feedback circuit is connected between the output load and the input DC power supply, and the high-frequency electrical isolation flyback converter energy feedback circuit consists of a cycloconverter and a high-frequency energy storage transformer 1. The rectifiers are cascaded in sequence, the input end of the cycloconverter is connected to the output load, and the output end of the rectifier is connected to the input DC power supply. The circuit topology of the high-frequency link inverter is push-pull full-wave, push-pull bridge, half-bridge full-wave, half-bridge, full-bridge full-wave or full-bridge circuit.

The circuit structure and circuit principle waveform of the boost (Boost) type high-frequency chain inverter are shown in Figure 1 and Figure 2 respectively. The relationship between the absolute value |u ₀ | of the instantaneous value of the low-frequency sinusoidal AC voltage output by the inverter at any moment and the input DC voltage U _i , the high-frequency transformer turn ratio N ₂ /N ₁ , and the duty cycle D is |u ₀ |=U _i N ₂ /[N ₁ (1-D)], for different duty cycle D and high-frequency transformer turn ratio N ₂ /N ₁ , the instantaneous output voltage greater than, equal to or less than U _i can be obtained The absolute value of the value |u ₀ |. Since 0<D<1, so |u ₀ |>U _i N ₂ /N ₁ , that is to say, at any time the absolute value of the instantaneous value of the low-frequency sinusoidal AC voltage output by the inverter |u ₀ | is always higher than the input The product of the DC voltage U _i and the high-frequency transformer turn ratio N ₂ /N ₁ (U _i N ₂ /N ₁ ), so this type of inverter is called a boost (Boost) high-frequency link inverter. The high-frequency inverter and cycloconverter in this circuit structure are composed of two-quadrant and four-quadrant high-frequency power switches respectively, and the energy storage inductor is located at the input side of the inverter. When the input DC power supply transmits power to the load, the high-frequency inverter modulates the pulsating DC current of the energy storage inductor into a bipolar three-state high-frequency pulse current, and the cycloconverter demodulates it into a unipolar three-state The low-frequency pulse current can get high-quality low-frequency sinusoidal AC voltage through the output filter; when the load feeds back energy to the input DC power supply, the cycloconverter will output the low-frequency sinusoidal AC voltage and modulate it into a bipolar three-state high-frequency pulse voltage. The high-frequency inverter demodulates it into unipolar three-state low-frequency pulse voltage, which is fed back to the input DC power supply after passing through the input filter. Since the Boost converter is essentially a step-up converter, there is always |u ₀ |>U _i N ₂ /N ₁ in each high-frequency switching cycle, so when the output sinusoidal voltage drops and |u ₀ |≤U _i During the N ₂ /N ₁ period (t=t ₁ ～ t ₂ , t ₃ ～ t ₄ intervals in the circuit principle waveform shown in Figure 2) the formation of the u ₀ waveform needs to be added by adding a cycle converter, a high-frequency energy storage type Transformers and rectifiers are sequentially cascaded to form a low-power high-frequency electrical isolation flyback Flyback converter energy feedback circuit.

Since the energy storage inductance of the boost (Boost) type high-frequency link inverter is located on the input side, the current on the input side is easy to control. In the continuous mode of the inductor current, the input current i _L is continuous, and the input current ripple is small. The electromagnetic interference (EMI) is small, and the ripple of the input direct current i _i is small. When the load is short-circuited, since the energy storage inductance of the boost (Boost) high-frequency link inverter can limit the current, the rising rate of the power switch current remains unchanged, and the allowable protection circuit operates for a long time, so the boost ( Boost) type high-frequency link inverter has high reliability when the load is short-circuited. Since the electrical isolation element in the boost (Boost) high-frequency link inverter is a high-frequency transformer, and the magnetic core works in a bidirectional symmetrical magnetization state, the boost (Boost) high-frequency link inverter can output large power. Therefore, the boost (Boost) high-frequency link inverter has significant advantages and an important position in large-capacity power conversion applications that require small power supply side ripple and high reliability when the load is short-circuited.

The embodiments of the boost (Boost) type high-frequency link inverter circuit topology family are shown in FIGS. 3 , 4 , 5 , 6 , 7 , and 8 . Figure 3 is a push-pull full-wave circuit, Figure 4 is a push-pull bridge circuit, Figure 5 is a half-bridge full-wave circuit, Figure 6 is a half-bridge circuit, Figure 7 is a full-bridge full-wave circuit, and Figure 8 is Full bridge bridge circuit. This circuit topology family is suitable for converting an unstable direct current into the required stable high-quality sinusoidal alternating current, and can be used to realize a new type of high-power inverter power supply with excellent performance and wide application prospects (such as 24VDC/220V50HzAC, 48VDC/220V50HzAC ) and static converters (such as 27VDC/115V400HzAC, 270VDC/115V400HzAC). From the perspective of the high-frequency inverter on the input side, the maximum voltage stress borne by the high-frequency power switches S ₁ and S ₂ of the push-pull and half-bridge circuits is twice the amplitude of the output AC voltage converted to the primary side (2U _om N ₁ /N ₂ ), the utilization rate of the primary winding of the former transformer is low, while the utilization rate of the primary winding of the latter transformer is high; the high-frequency power switches S ₁ (S ₁ ′) and S ₂ (S ₂ ′) of the full-bridge circuit bear the The maximum voltage stress is converted to the output AC voltage amplitude of the primary side (U _om N ₁ /N ₂ ), and the utilization rate of the primary winding of the transformer is high. From the cycloconverter on the output side, the maximum voltage stress borne by the high-frequency power switches S ₃ and S ₄ of the full-wave circuit is twice the amplitude of the output AC voltage (2U _om ), and the utilization rate of the secondary winding of the transformer is low; The maximum voltage stress of the high-frequency power switches S ₃ (S ₃ ′) and S ₄ (S ₄ ′) in the formula circuit is the amplitude of the output AC voltage (U _om ), and the utilization rate of the secondary winding of the transformer is high. Therefore, the push-pull full-wave, half-bridge full-wave, and full-bridge full-wave circuits are suitable for low-voltage, high-current, and large-capacity output inverter occasions, and the push-pull bridge, half-bridge, and full-bridge bridge circuits are suitable for high-voltage Small current, large capacity output inverter occasions.

A low-power high-frequency electrical isolation flyback flyback converter energy feedback circuit is set in this circuit topology family, which is composed of a four-quadrant power switch S _a and a high-frequency energy storage transformer with a secondary winding center tap T _a and two unidirectional current power switches (S _a1 and D _a1 are in reverse series, S _a2 and D _a2 are in reverse series). The four-quadrant power switch S _a will output a sinusoidal voltage drop and |u ₀ |≤U _i N ₂ /N ₁ period (t=t ₁ ~ t ₂ , t ₃ ~ t ₄ intervals in the circuit principle waveform shown in Figure 2) Excessive energy is modulated into a high-frequency pulsating current and stored in the high-frequency energy storage transformer T _a . When S _a is cut off and S _a1 or S _a2 is turned on, the energy stored in the high-frequency energy storage transformer T _a Released to the input DC power side. Therefore, the function of the specially set low-power high-frequency electrical isolation flyback converter is to feed back the excessive output energy during the output sinusoidal voltage drop and |u ₀ |≤U _i N ₂ /N ₁ to the input DC power supply side to ensure a high-quality output sinusoidal voltage waveform at the output.

The boost (Boost) high-frequency link inverter adopts the voltage instantaneous value feedback control principle, as shown in Figure 9 and Figure 10. In this control principle, Fig. 9 is a control block diagram, and Fig. 10 is a control principle waveform. In the interval of output sinusoidal voltage t=0～t ₁ , t ₂ ～t ₃ , the power circuit of the inverter is in the working state, while the energy feedback circuit is in the stop working state. The control principle can be briefly described as: the inverter outputs sinusoidal AC The absolute value signal of the voltage feedback signal u _of is compared with the absolute value signal of the reference sinusoidal signal u _ref , the error amplification signal u _e is obtained after the error amplifier, and the SPWM signal is obtained by comparing the error amplification signal u _e with the sawtooth carrier signal u _c u _k3 , the saw-tooth carrier signal u _c gets the pulse signal u _k1 after passing through the falling edge two frequency division circuit, u _k1 gets the pulse signal u _k2 through the NOT gate circuit, the SPWM signal u _k3 is ORed with the pulse signals u _k1 and u _k2 respectively And then respectively with the gating signal u _sy of the converter (u _e is obtained through the zero comparator), and after the drive circuit, the four-quadrant high-frequency power switches S ₁ (S ₁ ′), S ₂ (S ₂ ′) are obtained Drive signal, that is, S ₁ (S′ ₁ )=(u _k1 +u _k3 )·u _sy , S ₂ (S′ ₂ )=(u _k2 +u _k3 )·u _sy =(u _k1 +u _k3 )· U _sy , SPWM signal u _k3 and pulse signal u _k1 , u _k2 respectively through the OR gate and NOT gate circuit are respectively used as the four-quadrant high-frequency power switch S ₄ (S ₄ ′) in the positive and negative half cycles of the output voltage The driving signal and the driving signal of the four-quadrant high-frequency power switch S ₃ (S ₃ ′) in the negative and positive half cycles of the output voltage, that is, S ₄ (S ₄ ′)=(u _k3 +u _k1 ·u _k0 +u _k3 + u _k2 ·u _k0 )·u _sy 、 S ₃ (S ₃ ′)＝(u _k3 +u _k1 ·u _k0 +u _k3 +u _k2 ·u _k0 )·u _sy ; and in this interval u _e >0, -u _e <0, -u _e has no intersection with _uc , the gating signal _usy =1, _usy =0 of the converter, so the driving signals of the power switches S _a , S _a1 and S _a2 are all blocked. In the interval of output sinusoidal voltage t=t ₁ ～t ₂ , t ₃ ～t ₄ , the power circuit of the inverter is in the stop working state, while the energy feedback circuit is in the working state. No. u _sy = 1, u _sy = 0, so four-quadrant high-frequency power switches S ₁ (S ₁ ′), S ₂ (S ₂ ′), S ₃ (S ₃ ′), S ₄ (S ₄ ′) The driving signals are all blocked; and in this interval u _e < 0, - u _e > 0, -u _e and u _c get the driving signal of the four-quadrant power switch S _a after passing through the comparator and the driving circuit, and the -u _e The signals from the comparator and the inverting gate and the strobe signal u _sy of the converter are phase-ANDed with u _c , and then the driving signals of S _a1 and S _a2 are obtained after the output voltage positive and negative half-cycle selection signals u _k0 and u _k0 . During the working period of the energy feedback circuit, the four-quadrant power switch S _a modulates the excessive output energy in the intervals of t=t ₁ ~ t ₂ and t ₃ ~ t ₄ into a high-frequency pulsating current and stores it in the high-frequency energy storage transformer T _a , when S _a is cut off and S _a1 or S _a2 is turned on, the energy stored in T _a is released to the input DC power supply side, thus completing the feedback of excessive output energy.

For the push-pull, half-bridge, and full-bridge circuits shown in Figure 3 to Figure 8, the two-quadrant high-frequency power switches S ₁ (S ₁ ′) and S ₂ (S ₂ ′) of the input-side high-frequency inverter The drive signals differ by 180° and the duty cycle is greater than 0.5, and their common conduction time within T _s /2 is T _com = (T _s /2)θ/180° (Ts is the high-frequency switching period, 0<θ< 180° is the angle corresponding to the common conduction time), and the duty ratio D=T _com /(T _s /2)=θ/180°. By changing the common conduction angle of the high-frequency inverter on the input side, the duty cycle D of the bipolar tri-state high-frequency pulse current _i1 can be adjusted (changing the duty cycle of the drive signal), so that when the input voltage Or the stability and regulation of the output voltage of the boost (Boost) high-frequency link inverter when the load changes.

Claims (2)

1. voltage increase high-frequency link reverser, it is characterized in that: by input filter circuit, energy storage inductor, high-frequency inverter, high frequency transformer, frequency converter, output filter circuit cascade in regular turn constitutes, and between output loading and input DC power, be connected with high frequency electrical isolation inverse excitation type converter energy feedback circuit, described high frequency electrical isolation inverse excitation type converter energy feedback circuit is by frequency converter, the high frequency storage transformer, rectifier cascade in regular turn constitutes, the input of frequency converter is connected with output loading, and the output of rectifier is connected with input DC power.

2. voltage increase high-frequency link reverser according to claim 1 is characterized in that: described high-frequency chain inverter circuit topology is for recommending full wave type, push-pull bridge, half-bridge full wave type, half-bridge bridge-type, full-bridge full wave type or full-bridge bridge circuit.

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