High-voltage, low-ripple photovoltaic-energy storage power supply system

Abstract

This invention discloses a high-boost, low-ripple photovoltaic and energy storage power supply system. It includes a battery-side power conversion circuit, a photovoltaic-side power conversion circuit, a bus capacitor, an output filter capacitor, and a load resistor. The positive terminals of the battery-side and photovoltaic-side power conversion circuits are connected to one end of the output filter capacitor and the load resistor. The bus terminals of the battery-side and photovoltaic-side power conversion circuits are connected to one end of the bus capacitor. The negative terminals of the battery-side and photovoltaic-side power conversion circuits, the other end of the output filter capacitor and the load resistor, and the other end of the bus capacitor are all connected to ground. This invention significantly improves the boost capability of the circuit and reduces the ripple of the photovoltaic and battery currents.

Description

Technical Field

[0001] This invention relates to a non-isolated DC-DC circuit, specifically to a high-boost, low-ripple photovoltaic-energy storage power supply system, belonging to the field of power electronic conversion and power supply systems, and particularly to the field of DC-DC power conversion technology. Background Technology

[0002] Photovoltaic power generation, as a major form of new energy power generation, has been widely used. Because the output of photovoltaic cells fluctuates due to weather and other factors, they are usually combined with batteries to provide a stable energy output. However, the output voltage of photovoltaic cells and batteries is typically low, and traditional boost circuits struggle to efficiently boost it to higher levels. Furthermore, the lifespan of photovoltaic cells and batteries is affected by their output current ripple; the larger the ripple, the shorter the lifespan, which places higher demands on the converter. Summary of the Invention

[0003] To address the above problems, this invention proposes a high-voltage, low-ripple photovoltaic-energy storage power supply system.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A high-voltage, low-ripple photovoltaic-energy storage power supply system comprises a battery-side power conversion circuit (1), a photovoltaic-side power conversion circuit (2), and a bus capacitor (…). C Bus ), output filter capacitor ( C o ) and load resistance ( R o The battery-side power conversion circuit (1) and the photovoltaic-side power conversion circuit (2) are composed of a positive terminal (+) connected to the output filter capacitor. C o ) and load resistance ( R o One end of the battery-side power conversion circuit (1) and the photovoltaic-side power conversion circuit (2) are connected to the bus terminal (Bus) of the bus capacitor. C Bus One end of the battery-side power conversion circuit (1) and the negative terminal (-) of the photovoltaic-side power conversion circuit (2), and the output filter capacitor ( C o ) and load resistance ( R o The other end of the bus capacitor () C Bus The other end of each is connected to the ground; The battery-side power conversion circuit (1) includes a first DC power supply ( V Bat ), third filter inductor (L 3) Fourth filter inductor ( L 4) Third switching transistor ( S 3) Fourth switching transistor ( S 4) Fifth switching transistor ( S 5) Sixth switching transistor ( S 6) Third voltage regulator capacitor ( C 3) Fourth voltage regulator capacitor ( C 4) Sixth diode ( D 6) Seventh diode ( D 7) Eighth diode ( D 8); the first DC power supply ( V Bat The positive terminal of ) is connected to the third filter inductor ( L 3) and the fourth filter inductor ( L 4) at one end, the third filter inductor ( L 3) The other end is connected to the third voltage regulator capacitor ( C 3) one end, the fifth switch ( S 5) emitter and sixth switch ( S 6) collector, fourth filter inductor ( L 4) The other end is connected to the fourth voltage regulator capacitor ( C 4) One end, the third switch ( S 3) emitter and fourth switch ( S 4) collector, fourth switch ( S 4) Emitter, sixth switch ( S 6) emitter and first DC power supply ( V Bat The negative terminals of all three capacitors are connected to the negative terminal (-) of the power conversion circuit (1) on the battery side, and the third voltage regulator capacitor ( C 3) The other end is connected to the eighth diode ( D 8) cathode and seventh diode ( D 7) anode, the eighth diode ( D 8) anode, third switch ( S 3) collector and fifth switch ( S The collectors of 5) are all connected to the bus terminal (Bus) of the power conversion circuit (1) on the battery side, and the fourth voltage regulator capacitor ( C 4) The other end is connected to the seventh diode ( D 7) cathode and sixth diode ( D 6) anode, sixth diode ( D The cathode of 6) is connected to the positive terminal (+) of the power conversion circuit (1) on the battery side; The photovoltaic-side power conversion circuit (2) includes a second DC power supply (V PV ), first filter inductor ( L 1) Second filter inductor ( L 2) First switching transistor ( S 1) Second switching transistor ( S 2) First voltage regulator capacitor ( C 1) Second voltage regulator capacitor ( C 2) First diode ( D 1) Second diode ( D 2) Third diode ( D 3) Fourth diode ( D 4) Fifth diode ( D 5); the second DC power supply ( V PV The positive terminal of ) is connected to the first filter inductor ( L 1) and the second filter inductor ( L 2) One end, the first filter inductor ( L 1) The other end is connected to the first voltage regulator capacitor ( C 1) one end, the first diode ( D 1) anode, first switching transistor ( S 1) collector, second filter inductor ( L 2) The other end is connected to the second voltage regulator capacitor ( C 2) One end, the second diode ( D 2) anode and second switching transistor ( S 2) collector, second switching transistor ( S 2) and the first switching transistor ( S 1) Emitter, second DC power supply ( V PV The negative terminals of all capacitors are connected to the negative terminal (-) of the photovoltaic power conversion circuit, and the first voltage regulator capacitor ( C 1) The other end is connected to the third diode ( D 3) cathode and fourth diode ( D 4) anode, first diode ( D 1) and the second diode ( D 2) Cathode, third diode ( D 3) The anodes are all connected to the bus terminals of the photovoltaic-side power conversion circuit. Bus ), second voltage regulator capacitor ( C 2) The other end is connected to the fourth diode ( D 4) cathode and fifth diode ( D 5) anode, fifth diode ( D 5) The cathode is connected to the positive terminal (+) of the photovoltaic power conversion circuit.

[0005] This invention provides a high-voltage, low-ripple photovoltaic-energy storage power supply system, which has the following advantages compared with the prior art: (1) This invention significantly improves the boost capability of the circuit; (2) This invention reduces the current ripple of photovoltaic cells and batteries through interleaved parallel control. Attached Figure Description

[0006] Appendix Figure 1 This is a circuit diagram of a high-voltage, low-ripple photovoltaic-energy storage power supply system proposed in this invention. Appendix Figure 2 This invention describes the specific structure of a battery-side power conversion circuit in a high-boost, low-ripple photovoltaic-energy storage power supply system. Appendix Figure 3 This invention describes the specific structure of a photovoltaic-side power conversion circuit in a high-boost, low-ripple photovoltaic-energy storage power supply system. Appendix Figure 4 yes Figure 2 The circuit shown has a duty cycle of D Timing analysis waveforms with a value <0.5; Appendix Figure 5 yes Figure 2 The circuit shown has a duty cycle of D Timing analysis waveforms >0.5; Appendix Figure 6 yes Figure 2 The circuit shown operates in the equivalent circuit of mode one; Appendix Figure 7 yes Figure 2 The circuit shown is the equivalent circuit for mode two. Appendix Figure 8 yes Figure 2 The circuit shown is the equivalent circuit for mode three. Appendix Figure 9 yes Figure 2 The circuit shown is the equivalent circuit for mode four. In the above attached figures, v GS3 , v GS4 , v GS5 , v GS6 They represent the switching transistors respectively. S 3. S 4. S 5. S The driving voltage waveform of 6, i L3 , i L4 respectively flowing through the inductor L3 and inductance L The current waveform of 4, i Bat This represents the total output current waveform on the battery side. V C3 , V C4 , V Bus and V o The third voltage regulator capacitor C 3. Fourth voltage regulator capacitor C 4. Bus capacitor C Bus and output filter capacitor C o The voltage on, D For the fourth switching transistor S A duty cycle of 4. Detailed Implementation

[0007] The present invention will now be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0008] As attached Figure 1 As shown, the high-boost, low-ripple photovoltaic-energy storage power supply system consists of a battery-side power conversion circuit (1), a photovoltaic-side power conversion circuit (2), and a bus capacitor (…). C Bus ), output filter capacitor ( C o ) and load resistance ( R o The battery-side power conversion circuit (1) and the photovoltaic-side power conversion circuit (2) are composed of a positive terminal (+) connected to the output filter capacitor. C o ) and load resistance ( R o One end of the battery-side power conversion circuit (1) and the photovoltaic-side power conversion circuit (2) are connected to the bus terminal (Bus) of the bus capacitor. C Bus One end of the battery-side power conversion circuit (1) and the negative terminal (-) of the photovoltaic-side power conversion circuit (2), and the output filter capacitor ( C o ) and load resistance ( R o The other end of the bus capacitor () C Bus The other end of each is connected to the ground; As attached Figure 2 As shown, the battery-side power conversion circuit (1) includes a first DC power supply (V Bat ), third filter inductor ( L 3) Fourth filter inductor ( L 4) Third switching transistor ( S 3) Fourth switching transistor ( S 4) Fifth switching transistor ( S 5) Sixth switching transistor ( S 6) Third voltage regulator capacitor ( C 3) Fourth voltage regulator capacitor ( C 4) Sixth diode ( D 6) Seventh diode ( D 7) Eighth diode ( D 8); the first DC power supply ( V Bat The positive terminal of ) is connected to the third filter inductor ( L 3) and the fourth filter inductor ( L 4) at one end, the third filter inductor ( L 3) The other end is connected to the third voltage regulator capacitor ( C 3) one end, the fifth switch ( S 5) emitter and sixth switch ( S 6) collector, fourth filter inductor ( L 4) The other end is connected to the fourth voltage regulator capacitor ( C 4) One end, the third switch ( S 3) emitter and fourth switch ( S 4) collector, fourth switch ( S 4) Emitter, sixth switch ( S 6) emitter and first DC power supply ( V Bat The negative terminals of all three capacitors are connected to the negative terminal (-) of the power conversion circuit (1) on the battery side, and the third voltage regulator capacitor ( C 3) The other end is connected to the eighth diode ( D 8) cathode and seventh diode ( D 7) anode, the eighth diode ( D 8) anode, third switch ( S 3) collector and fifth switch ( S The collectors of 5) are all connected to the bus terminal (Bus) of the power conversion circuit (1) on the battery side, and the fourth voltage regulator capacitor ( C 4) The other end is connected to the seventh diode ( D 7) cathode and sixth diode ( D 6) anode, sixth diode ( D The cathode of 6) is connected to the positive terminal (+) of the power conversion circuit (1) on the battery side; As attached Figure 3 As shown, the photovoltaic-side power conversion circuit (2) includes a second DC power supply ( V PV ), first filter inductor ( L 1) Second filter inductor ( L 2) First switching transistor ( S 1) Second switching transistor ( S 2) First voltage regulator capacitor ( C 1) Second voltage regulator capacitor ( C 2) First diode ( D 1) Second diode ( D 2) Third diode ( D 3) Fourth diode ( D 4) Fifth diode ( D 5); the second DC power supply ( V PV The positive terminal of ) is connected to the first filter inductor ( L 1) and the second filter inductor ( L 2) One end, the first filter inductor ( L 1) The other end is connected to the first voltage regulator capacitor ( C 1) one end, the first diode ( D 1) anode, first switching transistor ( S 1) collector, second filter inductor ( L 2) The other end is connected to the second voltage regulator capacitor ( C 2) One end, the second diode ( D 2) anode and second switching transistor ( S 2) collector, second switching transistor ( S 2) and the first switching transistor ( S 1) Emitter, second DC power supply ( V PV The negative terminals of all capacitors are connected to the negative terminal (-) of the photovoltaic power conversion circuit, and the first voltage regulator capacitor ( C 1) The other end is connected to the third diode ( D 3) cathode and fourth diode ( D 4) anode, first diode ( D 1) and the second diode ( D 2) Cathode, third diode ( D 3) The anodes are all connected to the bus terminals of the photovoltaic-side power conversion circuit. Bus ), second voltage regulator capacitor ( C 2) The other end is connected to the fourth diode ( D 4) cathode and fifth diode ( D 5) anode, fifth diode (D 5) The cathode is connected to the positive terminal (+) of the photovoltaic power conversion circuit.

[0009] like Figure 4 For the appendix Figure 2 The battery-side power conversion circuit shown is in D Control timing diagram when <0.5, third switching transistor S 3 and the fourth switching transistor S 4. Complementary conduction, fifth switching transistor S 5 and the sixth switching transistor S 6 complementary conduction, fourth switch S 4 and the sixth switching transistor S The duty cycle D of the 6 drive signals is the same but the phase difference is 180°. The duty cycle D is adjusted by the fourth switch. Appendix Figure 2 The battery-side power conversion shown is in D The principle for <0.5 is as follows: when Figure 2 The circuit shown has a duty cycle D < 0.5 and operates in (0- t When 1), the equivalent circuit is as follows: Figure 6 Mode 1 is shown: t When =0, the fourth switching transistor S 4 and the fifth switching transistor S 5. When the circuit is on, the inductor current... i L3 Decrease, inductor current i L4 Rising, seventh diode D 7 is on, bus capacitor voltage V Bus and the voltage of the third stabilizing capacitor V C3 The voltage of the fourth voltage regulator capacitor is connected in series. V C4 Charging, capacitor voltage V C4 satisfy: V C4 = V Bus + V C3 (1) when Figure 2 The circuit shown has a duty cycle D < 0.5 and operates in ( ) t 1- t 2) When the equivalent circuit is as follows: Figure 7 Mode 2 is shown: t At time 1, the fourth switch transistor S 4. Turn off, third switch tube S 3. When the circuit is on, the inductor current... iL3 and i L4 All decreased, sixth diode D 6 is on, bus capacitor voltage V Bus and the voltage of the fourth voltage regulator capacitor V C4 Series connection for output voltage V o Charging, output voltage V o satisfy: V o = V Bus + V C4 =2 V Bus + V C3 (2) when Figure 2 The circuit shown has a duty cycle D < 0.5 and operates in ( ) t 2- t 3) When the equivalent circuit is as follows: Figure 7 Mode 2 is shown: t At time 2, the fifth switch transistor S 5. Turn off, sixth switch transistor S 6 is on, inductor current i L3 Rise, inductor current i L4 Decrease, sixth diode D Diodes 6 and 8 D 8 is on, bus capacitor voltage V Bus and the voltage of the fourth voltage regulator capacitor V C4 Series connection for output voltage V o Charging, output voltage V o Satisfying equation (2), the bus capacitor voltage V Bus The voltage of the third stabilizing capacitor V C3 Charging, voltage of the third voltage regulator capacitor V C3 satisfy: V C3 = V Bus (3) when Figure 2 The circuit shown has a duty cycle D < 0.5 and operates in ( ) t 3-t When 4) the circuit operates in the same mode as mode two, it will not be described again here; like Figure 5 For the appendix Figure 2 The battery-side power conversion circuit shown is in D Control timing diagram when >0.5; Appendix Figure 2 The battery-side power conversion shown is in D The principle for <0.5 is as follows: when Figure 2 The duty cycle of the circuit shown D >0.5 and working in (0- t When 1), the equivalent circuit is as follows: Figure 8 Mode 3 is shown; when the duty cycle D >0.5 and Figure 2 The circuit shown operates at ( t 2- t 3) When the equivalent circuit is as follows: Figure 6 As shown in Mode 1; the working principle of these two cases is exactly the same as above, and will not be repeated here; when Figure 2 The duty cycle of the circuit shown D >0.5 and working at ( t 1- t 2) When the equivalent circuit is as follows: Figure 9 Mode 4 is shown: the fourth switching transistor S 4 and the sixth switch S 6 is on, inductor current i L3 and i L4 All increased, the eighth diode D 8 is on, bus capacitor voltage V Bus The voltage of the third stabilizing capacitor V C3 Charging, voltage of the third voltage regulator capacitor V C3 Satisfy equation (3); when Figure 2 The duty cycle of the circuit shown D >0.5 and working at ( t 3- t When 4) the circuit operates in the same mode as mode four, it will not be described again here; Due to the first DC power supply V Bat Third filter inductor L 3. Fifth switching transistor S 5. Sixth switching transistor S 6 and bus capacitor voltage V BusThis constitutes a Boost circuit with synchronous rectification function, due to the first DC power supply. V Bat Fourth filter inductor L 4. Third switching transistor S 3. Fourth switching transistor S 4 and bus capacitor voltage V Bus This forms another Boost circuit with synchronous rectification function, and the two are connected in parallel in an alternating manner, thus the first DC power supply V Bat and bus capacitor voltage V Bus satisfy: V Bus = V Bat / (1-D) (4) Combining equations (1)-(4), we can obtain: V o =3 V Bat / (1-D) (5) As can be seen from equation (5), the voltage gain of the circuit proposed in this invention is three times that of the ordinary Boost circuit, and it has a higher gain. In addition, due to the inductor current i L3 and i L4 A phase difference of 180° affects the battery-side current. i in Smaller pulsations can effectively extend battery life; The photovoltaic-side power conversion circuit described above is structurally similar to the battery-side power conversion circuit, but it takes into account the second DC power supply on the photovoltaic side. V PV With bus capacitor C Bus The unidirectional power transfer between them necessitates the use of a first diode instead of a synchronous rectifier. D 1 and second diodes D 2. Two diodes; their working principles are similar, so they will not be elaborated here. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-voltage, low-ripple photovoltaic-energy storage power supply system, comprising a battery-side power conversion circuit (1), a photovoltaic-side power conversion circuit (2), and a bus capacitor ( C Bus ), output filter capacitor ( C o ) and load resistance ( R o The battery-side power conversion circuit (1) and the photovoltaic-side power conversion circuit (2) are composed of a positive terminal (+) connected to the output filter capacitor. C o ) and load resistance ( R o One end of the battery-side power conversion circuit (1) and the photovoltaic-side power conversion circuit (2) are connected to the bus terminal (Bus) of the bus capacitor. C Bus One end of the battery-side power conversion circuit (1) and the negative terminal (-) of the photovoltaic-side power conversion circuit (2), and the output filter capacitor ( C o ) and load resistance ( R o The other end of the bus capacitor () C Bus The other end of each is connected to the ground; The battery-side power conversion circuit (1) includes a first DC power supply ( V Bat ), third filter inductor ( L 3) Fourth filter inductor ( L 4) Third switching transistor ( S 3) Fourth switching transistor ( S 4) Fifth switching transistor ( S 5) Sixth switching transistor ( S 6) Third voltage regulator capacitor ( C 3) Fourth voltage regulator capacitor ( C 4) Sixth diode ( D 6) Seventh diode ( D 7) Eighth diode ( D 8); the first DC power supply ( V Bat The positive terminal of ) is connected to the third filter inductor ( L 3) and the fourth filter inductor ( L 4) at one end, the third filter inductor ( L 3) The other end is connected to the third voltage regulator capacitor ( C 3) one end, the fifth switch ( S 5) emitter and sixth switch ( S 6) collector, fourth filter inductor ( L 4) The other end is connected to the fourth voltage regulator capacitor ( C 4) One end, the third switch ( S 3) emitter and fourth switch ( S 4) collector, fourth switch ( S 4) Emitter, sixth switch ( S 6) emitter and first DC power supply ( V Bat The negative terminals of all three capacitors are connected to the negative terminal (-) of the power conversion circuit (1) on the battery side, and the third voltage regulator capacitor ( C 3) The other end is connected to the eighth diode ( D 8) cathode and seventh diode ( D 7) anode, the eighth diode ( D 8) anode, third switch ( S 3) collector and fifth switch ( S The collectors of 5) are all connected to the bus terminal (Bus) of the power conversion circuit (1) on the battery side, and the fourth voltage regulator capacitor ( C 4) The other end is connected to the seventh diode ( D 7) cathode and sixth diode ( D 6) anode, sixth diode ( D The cathode of 6) is connected to the positive terminal (+) of the power conversion circuit (1) on the battery side; The photovoltaic-side power conversion circuit (2) includes a second DC power supply ( V PV ), first filter inductor ( L 1) Second filter inductor ( L 2) First switching transistor ( S 1) Second switching transistor ( S 2) First voltage regulator capacitor ( C 1) Second voltage regulator capacitor ( C 2) First diode ( D 1) Second diode ( D 2) Third diode ( D 3) Fourth diode ( D 4) Fifth diode ( D 5); the second DC power supply ( V PV The positive terminal of ) is connected to the first filter inductor ( L 1) and the second filter inductor ( L 2) One end, the first filter inductor ( L 1) The other end is connected to the first voltage regulator capacitor ( C 1) one end, the first diode ( D 1) anode, first switching transistor ( S 1) collector, second filter inductor ( L 2) The other end is connected to the second voltage regulator capacitor ( C 2) One end, the second diode ( D 2) anode and second switching transistor ( S 2) collector, second switching transistor ( S 2) and the first switching transistor ( S 1) Emitter, second DC power supply ( V PV The negative terminals of all capacitors are connected to the negative terminal (-) of the photovoltaic power conversion circuit, and the first voltage regulator capacitor ( C 1) The other end is connected to the third diode ( D 3) cathode and fourth diode ( D 4) anode, first diode ( D 1) and the second diode ( D 2) Cathode, third diode ( D 3) The anodes are all connected to the bus terminals of the photovoltaic-side power conversion circuit. Bus ), second voltage regulator capacitor ( C 2) The other end is connected to the fourth diode ( D 4) cathode and fifth diode ( D 5) anode, fifth diode ( D 5) The cathode is connected to the positive terminal (+) of the photovoltaic power conversion circuit.

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