阅读说明：本技术 串联型光伏高压直流并网变换器拓扑电路及调制方法 (Topological circuit of series photovoltaic high-voltage direct-current grid-connected converter and modulation method ) 是由 王环 黄欣科 王一波 于 2019-10-25 设计创作，主要内容包括：本发明属于光伏高压变换器技术领域,具体涉及了一种串联型光伏高压直流并网变换器拓扑电路及调制方法,旨在解决现有技术拓扑结构复杂、变换环节多、实用性差、升压比低的问题。本发明拓扑电路包括：高频变压器,用于隔离原边电路、副边电路；原边电路包括高频全桥逆变电路、有源钳位电路、C<Sub>1</Sub>、D<Sub>0</Sub>、L<Sub>1</Sub>,调整拓扑电路的升压、降压模式；副边电路包括高频整流电路、C<Sub>3</Sub>、C<Sub>4</Sub>,对高频变压器输出电压进行整流滤波；副边电路还包括开关管Q<Sub>5</Sub>,将副边电路调整为电压倍增电路,实现高频变压器输出电压倍压。本发明无需给输出电容预充电,从零电压进入降压模式逐渐过渡到升压模式,实现软启动,通过宽范围调节拓扑升压比,实现输入输出电压匹配。(The invention belongs to the technical field of photovoltaic high-voltage converters, and particularly relates to a topological circuit of a series photovoltaic high-voltage direct-current grid-connected converter and a modulation method, aiming at solving the problems of complex topological structure, more conversion links, poor practicability and low boost ratio in the prior art. The topology circuit of the present invention includes: the high-frequency transformer is used for isolating the primary side circuit and the secondary side circuit; the primary circuit comprises a high-frequency full-bridge inverter circuit, an active clamping circuit and a capacitor 1 、D 0 、L 1 Adjusting the voltage boosting and reducing modes of the topology circuit; the secondary circuit comprises a high-frequency rectification circuit and a secondary circuit 3 、C 4 Rectifying and filtering the output voltage of the high-frequency transformer; the secondary side circuit also comprises a switching tube Q 5 And the secondary side circuit is adjusted to be a voltage multiplying circuit, so that the voltage multiplication of the output voltage of the high-frequency transformer is realized. The invention gradually transits from zero voltage to step-down mode to step-up mode without pre-charging the output capacitorAnd in the mode, soft start is realized, and input and output voltage matching is realized by adjusting the topology boosting ratio in a wide range.)

1. A series connection type photovoltaic high-voltage direct-current grid-connected converter topological circuit is characterized by comprising a high-frequency transformer, a primary side circuit and a secondary side circuit;

the high-frequency transformer is used for isolating the primary side circuit and the secondary side circuit;

the primary side circuit comprises a high-frequency full-bridge inverter circuit, an active clamping circuit and an input capacitor C₁An input diode D₀Boost inductor L₁(ii) a The positive electrode and the negative electrode of the direct-current side of the high-frequency full-bridge inverter circuit are respectively connected with the positive electrode and the negative electrode of the active clamping circuit; the input capacitor C₁Anode, input diode D₀Anode, boost inductor L₁The positive electrode is connected with the input positive electrode of the photovoltaic high-voltage direct-current grid-connected converter topological circuit; the input capacitor C₁The negative electrode is connected with the negative electrode of the active clamping circuit and the input negative electrode of the topological circuit of the photovoltaic high-voltage direct-current grid-connected converter; the input boost inductor L₁The negative electrode is connected with the positive electrode of the active clamping circuit; the input diode D₀A cathode and a clamping capacitor C in the active clamping circuit₂The positive electrodes are connected;

the secondary side circuit comprises a high-frequency rectifying circuit and a filter capacitor C₃Filter capacitor C₄(ii) a The positive electrode of the high-frequency rectifying circuit and the filter capacitor C₃The positive pole is connected with the negative pole of the high-frequency rectifying circuit and the filter capacitor C₄The negative electrodes are connected; the filter capacitor C₃Negative electrode and the filter capacitor C₄The positive electrodes are connected.

2. The series photovoltaic high-voltage direct current grid-connected converter topological circuit according to claim 1, wherein the high-frequency full-bridge inverter circuit comprises a switch tube Q₁And a switching tube Q₂And a switching tube Q₃And a switching tube Q₄；

The switch tube Q₁And the above-mentionedSwitch tube Q₃The positive electrodes of the two electrodes are connected;

the switch tube Q₂And the switching tube Q₄The negative electrodes are connected;

the switch tube Q₁And the negative electrode of the switch tube Q₂The positive electrodes of the two-phase transformer are connected and then connected to one end of the primary side of the high-frequency transformer;

the switch tube Q₃And the negative electrode of the switch tube Q₄The positive electrodes of the two high-frequency transformers are connected and then connected to the other end of the primary side of the high-frequency transformer.

3. The series photovoltaic high voltage direct current grid-connected converter topology circuit according to claim 1, wherein the active clamp circuit comprises a clamp switch Q₀A clamp capacitor C₂；

The clamping switch tube Q₀A positive electrode and the clamping capacitor C₂The positive electrodes are connected.

4. The series photovoltaic high voltage direct current grid-connected converter topology circuit according to claim 1, wherein the high frequency rectification circuit comprises a diode D₁Diode D₂Diode D₃Diode D₄；

The diode D₁And the diode D₃The cathodes of the two electrodes are connected;

the diode D₂And the diode D₄The anodes of the anode groups are connected;

the diode D₁And the diode D₂The cathodes of the two-way transformer are connected and then connected to one end of the secondary side of the high-frequency transformer;

the diode D₃And the diode D₄The cathodes of the two transformers are connected and then connected to the other end of the secondary side of the high-frequency transformer.

5. The series photovoltaic high-voltage direct current grid-connected converter topological circuit according to any one of claims 1 to 4, characterized in that the topological circuit further comprises a rectification filter-voltage multiplication adjusting circuit;

the rectification filter-voltage multiplication adjusting circuit comprises a switch tube Q₅(ii) a The switch tube Q₅The positive pole is connected with one input end of the high-frequency rectifying circuit, and the switching tube Q₅Negative electrode and the filter capacitor C₃Negative electrode, filter capacitor C₄The positive electrodes are connected.

6. A modulation method for a topological circuit of a series-connection type photovoltaic high-voltage direct-current grid-connected converter is characterized in that based on the topological circuit of the series-connection type photovoltaic high-voltage direct-current grid-connected converter in any one of claims 1 to 5, the modulation method comprises the following steps:

step S10, defining the switching tube Q of the high-frequency full-bridge inverter circuit in the topology circuit₁、Q₂、Q₃、Q₄Clamping switch tube Q in active clamping circuit₀Has a switching period of T and obtains a switching tube Q₁、Q₂、Q₃、Q₄Clamping switch tube Q₀The on waveform of (a);

step S20, based on the switch tube Q₁、Q₂、Q₃、Q₄Clamping switch tube Q₀And judging the switching tube Q according to the switching period T and the conduction waveform thereof₁And Q₃Whether the on-time is greater than the T/2 period, if so, go to step S30; otherwise, jumping to step S40;

step S30, switch tube Q₁And Q₃Is longer than the T/2 period, the topology circuit is in a boost mode: clamping switch tube Q based on input₀Boost mode control information for controlling the clamp switch Q₀At the switching tube Q₁Or Q₃Is turned on when turned off and is on at the switching tube Q₁And Q₃Turn off at the same time through a clamping capacitor C₂Absorption switching tube Q₁Or Q₃Spike voltage caused when turned off;

step S40, switch tube Q₁And Q₃Is less than the T/2 period, the topology circuit is in a buck mode: clamping switch tube Q based on input₀Control information of voltage reduction mode for controlling clamping switch tube Q₀Is always on.

7. The method for modulating the topological circuit of the series-connection type photovoltaic high-voltage direct-current grid-connected converter according to claim 6, wherein the switching tube Q₁、Q₂、Q₃、Q₄The conduction waveform is:

switch tube Q₂And Q₄In the switching period T, the switching tube Q is respectively conducted with T/2 and 180 degrees phase difference₁And Q₃The conducting phase difference is 180 degrees, the switch tube Q₁And Q₄The same phase, the switching tube Q₂And Q₃The phases are the same.

8. The method for modulating the topological circuit of the series-connection type photovoltaic high-voltage direct-current grid-connected converter according to claim 6, wherein a switching tube Q₁And Q₃The on-time is more than T/2 period and the switching tube Q₅When the circuit is conducted, the boost ratio of the topological circuit is as follows:

wherein G is_BOOSTRepresenting the boost ratio in boost mode, V_OUTRepresenting the output voltage, V, of the boost-mode topology_INRepresenting the input voltage of a boost mode topological circuit, n representing the voltage ratio of a secondary side to a primary side of a high-frequency transformer, and D representing a switching tube Q₁、Q₃The duty cycle of (c).

9. The method for modulating the topological circuit of the series-connection type photovoltaic high-voltage direct-current grid-connected converter according to claim 6, wherein a switching tube Q₁And Q₃Is less than T/2 period and the switching tube Q₅When the circuit is turned off, the boost ratio of the topological circuit is as follows:

wherein G is_BUCKRepresentative pressure reducing modeStep-up ratio of formula V_OUTRepresenting the output voltage, V, of the buck-mode topology_INRepresenting the input voltage of the topological circuit in the voltage reduction mode, n representing the voltage ratio of the secondary side to the primary side of the high-frequency transformer, and D representing the Q of the switching tube₁、Q₃The duty cycle of (c).

10. The series-connection type photovoltaic high-voltage direct-current grid-connected converter topological circuit modulation method according to any one of claims 6 to 9, characterized by further comprising a rectification filtering-voltage multiplication adjusting step, wherein the method comprises the following steps:

obtaining the switching tube Q₅And performs:

the switch tube Q₅The control information of (2) is a switching tube Q₅When the high-frequency transformer is turned off, the output voltage of the high-frequency transformer is rectified and filtered;

the switch tube Q₅The control information of (2) is a switching tube Q₅And when the high-frequency transformer is conducted, doubling the voltage of the output voltage of the high-frequency transformer.