阅读说明：本技术 一种单级式高增益五开关Boost型逆变器 (Single-stage high-gain five-switch Boost type inverter ) 是由 赵犇 皇甫宜耿 俞天瀛 马瑞卿 于 2019-11-07 设计创作，主要内容包括：本发明涉及一种单级式高增益五开关Boost型逆变器,针对带耦合电感的单级式Boost型逆变器的低压侧换相二极管损耗大的问题,通过引入一个开关管来移除低压侧两个换相二极管,从而减小低压侧二极管所带来的导通损耗,提高整体效率。以相同开关管参数计算并仿真比较所述拓扑与带有低压侧换相二极管的拓扑的损耗,以200W输出功率为例,导通损耗降低了近10W,占整体效率的近5％,可见所述拓扑的导通损耗降低效果明显。当输出功率进一步提升而输入电压进一步降低时,原带有低压侧换相二极管拓扑的导通损耗会进一步加大,所述拓扑优势将会更加明显。(The invention relates to a single-stage high-gain five-switch Boost type inverter, which aims at the problem of high loss of a low-voltage side commutation diode of the single-stage Boost type inverter with a coupling inductor, and removes two low-voltage side commutation diodes by introducing a switch tube, so that the conduction loss caused by the low-voltage side diodes is reduced, and the overall efficiency is improved. The loss of the topology and the topology with the low-voltage side commutation diode is calculated and simulated and compared by using the same switch tube parameters, the conduction loss is reduced by nearly 10W by taking 200W output power as an example, and accounts for nearly 5% of the overall efficiency, so that the effect of reducing the conduction loss of the topology is obvious. When the output power is further increased and the input voltage is further reduced, the conduction loss of the original topology with the low-voltage side phase-change diode is further increased, and the advantages of the topology are more obvious.)

1. A single-stage high-gain five-switch Boost type inverter is characterized by comprising M₁～M₅Switching tube, L_cpCoupling inductor, D boost diode, output filter network L_o-C_oAnd C_dcA decoupling capacitor; m₁Switch tube, M₃The source electrode of the switching tube is connected with the negative electrode of the power supply and is grounded; positive pole and L of power supply_cpWinding W of coupling inductor₁The same name end of the terminal is connected; m₁Drain electrode of switching tube, M₅Source electrode and winding W of switch tube₂End of same name, W₁Are connected with the non-homonymous terminal; c_oOutput filter capacitor and L_oAn inductor connected in series with one end of the inductor₄Source electrode and M of switch tube₃The drain electrode of the switch tube is connected with the other end of the switch tube and the switch M₂Source electrode and M of switch tube₅Switch with a switch bodyThe drain electrode of the tube is connected; m₂Switching tube and M₄Drain electrode of switch tube and DC bus capacitor C_dcConnected with the cathode of the diode D; anode of diode D and coupled inductor winding W₂Are connected with the non-homonymous terminal; in operation, R_LLoad and C_oThe output filter capacitors are connected in parallel.

2. The single-stage high-gain five-switch Boost-type inverter of claim 1, wherein: said L_cpThe number of turns of the primary winding of the coupling inductor is N₁Number of turns of secondary winding N₂The transformation ratio is N ═ N₂/N₁。

3. The single-stage high-gain five-switch Boost-type inverter of claim 2, wherein: the transformation ratio n is selected according to the required voltage gain.

Technical Field

The invention belongs to the field of power electronics, and relates to a single-stage high-gain five-switch Boost type inverter.

Background

In photovoltaic micro-inverter applications, the inverter is typically required to have high voltage gain due to the low output voltage of the individual photovoltaic panels and the high output grid side voltage. Generally, because of easy control and realization, a two-stage inverter is adopted, the first stage is a high-gain DC-DC converter, and the second stage is a common bridge inverter. However, due to lower cost and higher efficiency, single-stage inverters are increasingly attracting wide interest of researchers. In overview, the proposed schemes mainly relate to flyback, Boost, and Buck-Boost.

In the scheme adopted by the single-stage inverter, the voltage gain of the flyback topology can be very high due to the adoption of the transformer, however, the single-stage structure of the flyback topology has to be provided with a decoupling circuit to reduce the decoupling capacitance, so that the characteristic of simple structure of the flyback topology is weakened, the number of devices is increased, and the efficiency is reduced; most of Buck-Boost type topologies are still limited by limited voltage conversion ratio, and individual topologies can realize high conversion ratio, but the number of devices is greatly increased; boost type topologies have high voltage buses to make power decoupling simple, but most of the current topologies suffer from the disadvantage of limited gain.

The document proposes that a novel Boost type inverter topology greatly improves the voltage gain by introducing a coupling inductor, but due to a single-stage topology structure, two phase-change diodes are introduced at a low-voltage side, and the two phase-change diodes cause large conduction loss due to large current bearing, and when the input voltage is lower, the diode loss accounts for a larger proportion of the overall loss.

Disclosure of Invention

Technical problem to be solved

In order to avoid the defects of the prior art, the invention provides a single-stage high-gain five-switch Boost type inverter, which solves the problem that the loss of a low-voltage side commutation diode of the single-stage Boost type inverter with a coupling inductor is large. Two phase change diodes on the low-voltage side are removed by introducing a switching tube, so that the loss caused by the diodes on the low-voltage side is reduced, and the overall efficiency is improved.

Technical scheme

A single-stage high-gain five-switch Boost type inverter is characterized by comprising M₁～M₅Switching tube, L_cpCoupled inductor, D boost diodeTube, output filter network L_o-C_oAnd C_dcA decoupling capacitor; m₁Switch tube, M₃The source electrode of the switching tube is connected with the negative electrode of the power supply and is grounded; positive pole and L of power supply_cpWinding W of coupling inductor₁The same name end of the terminal is connected; m₁Drain electrode of switching tube, M₅Source electrode and winding W of switch tube₂End of same name, W₁Are connected with the non-homonymous terminal; c_oOutput filter capacitor and L_oAn inductor connected in series with one end of the inductor₄Source electrode and M of switch tube₃The drain electrode of the switch tube is connected with the other end of the switch tube and the switch M₂Source electrode and M of switch tube₅The drain electrode of the switching tube is connected; m₂Switching tube and M₄Drain electrode of switch tube and DC bus capacitor C_dcConnected with the cathode of the diode D; anode of diode D and coupled inductor winding W₂Are connected with the non-homonymous terminal; in operation, R_LLoad and C_oThe output filter capacitors are connected in parallel.

Said L_cpThe number of turns of the primary winding of the coupling inductor is N₁Number of turns of secondary winding N₂The transformation ratio is N ═ N₂/N₁。

The transformation ratio n is selected according to the required voltage gain.

Advantageous effects

The single-stage high-gain five-switch Boost type inverter provided by the invention aims at the problem that the loss of a low-voltage side commutation diode of the single-stage Boost type inverter with a coupling inductor is large, and two low-voltage side commutation diodes are removed by introducing one switching tube, so that the conduction loss caused by the low-voltage side diodes is reduced, and the overall efficiency is improved. The loss of the topology and the topology with the low-voltage side commutation diode is calculated and simulated and compared by using the same switch tube parameters, the conduction loss is reduced by nearly 10W by taking 200W output power as an example, and accounts for nearly 5% of the overall efficiency, so that the effect of reducing the conduction loss of the topology is obvious. When the output power is further increased and the input voltage is further reduced, the conduction loss of the original topology with the low-voltage side phase-change diode is further increased, and the advantages of the topology are more obvious.

Meanwhile, the topology keeps a single-stage compact topology structure, the number of devices is small, and the high-voltage direct-current bus can use a small decoupling capacitor, so that a decoupling circuit is prevented from being introduced or a capacitor with a large capacitance value is placed on the low-voltage side, and the reliability and the service life of the inverter can be improved.

Drawings

FIG. 1 is a proposed single-stage high-gain five-switch Boost type inverter topology

FIG. 2 is a diagram of the working mode of the present invention

FIG. 2(a) mode A

FIG. 2(B) mode B

FIG. 2(C) mode C

FIG. 2(d) Modal A'

FIG. 2(e) Modal B'

FIG. 2(f) mode C'

FIG. 3 illustrates the main operating waveforms of the present invention

Detailed Description

The invention will now be further described with reference to the following examples and drawings:

according to the technical scheme provided by the invention, the single-stage high-gain five-switch Boost type inverter comprises: comprising five switching tubes M₁～M₅Formed bridge circuit and coupling inductor L_cpBoost diode D and DC bus capacitor C_dcAn output filter network L_o-C_oAnd an equivalent load R_L. Wherein the number of turns of the primary winding of the coupling inductor is N₁Number of turns of secondary winding N₂The transformation ratio is N ═ N₂/N₁The required voltage gain can be achieved by reasonably designing the coupling inductance transformation ratio. By introducing a middle stage switching tube M in a full bridge circuit₅Two phase change diodes on the low-voltage side in the original circuit are removed, and the normal work of the inverter circuit can be realized through designed logic control.

The circuit connection relation of the topology is as follows: switch tube M₁、M₃The source of the power supply is connected with the cathode of the input power supply and is grounded; positive pole of input power supply and coupling inductor L_cpWinding W of₁The same name end of the terminal is connected; switch with a switch bodyPipe M₁Drain electrode of (1), M₅Source electrode of (2) and winding W₂End of same name, W₁Are connected with the non-homonymous terminal; load R_LAnd output filter capacitor C_oConnected in parallel and with the inductance L_oIn series connection with one end of the switch tube M₄Source electrode and switch tube M₃Is connected with the drain electrode of the switching tube M, and the other end of the switching tube M is connected with the drain electrode of the switching tube₂Source electrode and switch tube M₅Is connected with the drain electrode of the transistor; switch tube M₂And M₄Drain electrode of and DC bus capacitor C_dcConnected with the cathode of the diode D; anode of diode D and coupled inductor winding W₂Are connected to each other.

As shown in FIG. 1, the inverter comprises a switching tube M₁～M₅Coupled inductor L_cpBoost diode D, output filter network L_o-C_oLoad R_LDecoupling capacitor C_dcAnd the like. The required voltage gain can be achieved by adjusting the transformation ratio of the coupling inductor, and M is reasonably controlled₁～M₅The on/off of the switch enables the circuit to work correctly so as to obtain the required output alternating voltage or current.

When the output voltage is positive, the switch tube M₄Is always on, and the switch tube M₃Is always turned off by controlling the switch tube M₁、M₂And M₅The switching on and off of the voltage control circuit realizes the control of the output voltage.

The working mode of the topology is as follows: there are three operating modes in each switching cycle, with the topology operating in modes A, B and C when the output voltage is positive and in modes a ', B ', and C ' when the output voltage is negative.

When the output voltage is positive, the switch tube M₃Is always turned off, and the switch tube M₄Is always on, and is controlled by the control switch tube M₁、M₂And M₅The switching on and off of the voltage control circuit realizes the control of the output voltage.

Mode A: switch tube M₁And M₅Switching on and off tube M₂Turning off the input voltage source to the primary winding W of the coupled inductor₁Charging, simultaneous switching of the transistor M₄And M₁The switching on of the DC bus enables the DC bus to supply power to the load end. The circuit of the mode is as shown in figure 2(a)

Mode B: at D_bkT_sTime of day, switch tube M₅Switch-off and switch tube M₂When the current is switched on, the current passes through the switch tube M₄And M₂Follow current, and output capacitor to supply power to load. The input voltage source continues to supply the primary winding W of the coupling inductor₁And (6) charging. The circuit of this mode is shown as 2(b)

Mode C: at D_bstT_sTime of day, switch tube M₁And (4) switching off, charging the direct current bus capacitor by the input voltage source and the coupling inductor through the two windings and the diode D, and keeping the tubular state of the rest switches unchanged. The circuit of the mode is as shown in figure 2(c)

When the output voltage is negative, the switch tube M₂Is always on and M₅Always off by controlling M₁、M₃And M₄The switch (es) of (a) to achieve control of the output voltage, thereby obtaining the working modes A ', B ' and C '.

Mode A': switch tube M₁And M₃Switching on and off tube M₄Turning off, inputting a voltage source to the primary winding N of the coupling inductor₁Charging, simultaneous switching of the transistor M₂And M₃The switching on of the DC bus enables the DC bus to supply power to the load end in a reverse direction. The circuit of the mode is as shown in figure 2(d)

Mode B': at D_bkT_sTime of day, switch tube M₃Switch-off and switch tube M₄When the current is switched on, the current passes through the switch tube M₂And M₄Follow current, and output capacitor to supply power to load. The input voltage source continues to supply the primary winding N of the coupling inductor₁And (6) charging. The circuit of the mode is as shown in figure 2(e)

A mode C': at D_bstT_sTime of day, switch tube M₁And (4) switching off, charging the direct current bus capacitor by the input voltage source and the coupling inductor through the two windings and the diode D, and keeping the tubular state of the rest switches unchanged. The circuit of the mode is as shown in figure 2(f)

Wherein D is_bstFor the boosting duty ratio, the boosting duty ratio can be calculated according to the relation of input and output voltages or solved by a maximum power tracking algorithm;D_bkis a sinusoidally varying SPWM wave according to D_bkThe modulation of (2) can obtain sinusoidal alternating voltage or current at the output end. In this topology, D_bkIs less than D_bst。

The switching tube switching modes of the topology are shown in table 1.

TABLE 1 topology switch modalities

When the output voltage is negative, the switch tube M₂Is always on and M₅Always off by controlling M₁、M₃And M₄The output voltage is controlled, so as to obtain the operation modes a ', B ', and C ', as shown in fig. 2(d), 2(e), and 2 (f).

The main operating waveforms of the topology are shown in FIG. 3, where S_M1～S_M5Are respectively a switch tube M₁～M₅The switching signal of (2). By comparing the duty ratio D_bstThe required direct current bus voltage can be obtained through the adjustment; by duty cycle D_bkThe required sinusoidal output waveform can be obtained by the adjustment of (2).