A main circuit of a marine constant frequency voltage stabilizing power supply and its working method

Abstract

A main circuit of a ship-borne constant frequency and voltage-stabilized power supply and a working method thereof, relates to a ship-borne constant frequency and voltage-stabilized power supply and a working method thereof, the main circuit comprises a rectifier circuit, a pre-charge circuit, an energy storage filter circuit, an inverter circuit and an output filter circuit, and is characterized in that a boost circuit is provided between the pre-charge circuit and the energy storage filter circuit, the boost circuit is a DC-DC boost circuit composed of an inductor, an IGBT and a diode, and an input protection circuit is provided at the front end of the rectifier circuit. During operation, the shaft belt generator generates electricity and supplies it to electrical equipment after rectification and inversion, the boost circuit is controlled according to the DC bus voltage, and the input protection circuit is controlled according to the DC bus voltage, the circuit and the duty cycle. The present invention has a simple structure, low cost, long service life, saves light oil, and effectively protects marine electrical appliances.

Description

Technical Field

[0001] The invention relates to a ship constant frequency voltage stabilizing power supply and a working method thereof, in particular to a main circuit of the ship constant frequency voltage stabilizing power supply which has a simple structure, low cost, long service life and can effectively protect ship electrical appliances and a working method thereof. Background Art

[0002] We know that in offshore fishing vessels, in order to save expensive light oil, the auxiliary engine on board should be avoided. Existing and newly produced fishing vessels are equipped with shaft generators directly connected to the diesel main engine. Such shaft generators are generally synchronous generators. When the ship is sailing and operating, the diesel main engine is always working, which drives the shaft generator to generate electricity for the use of marine electrical appliances.

[0003] When the ship is operating, the speed of the diesel engine is unstable, sometimes high and sometimes low, which causes the frequency and voltage of the electricity generated by the shaft generator to be unstable, and the marine electrical appliances are often burned out. When the diesel engine is idling, the frequency and voltage of the electricity generated by the shaft generator cannot meet the power requirements of the electrical appliances, and the auxiliary engine must be turned on, wasting energy.

[0004] Although the shaft generator is equipped with an excitation regulation circuit, it can only adjust the voltage but not the frequency, and can only improve this situation within a certain range, and cannot provide stable power supply under all working conditions of the diesel main engine. What is more serious is that when the ship is running at high speed, once the excitation regulation circuit fails, the power generated by the shaft generator may exceed the limit of the electrical equipment. Summary of the invention

[0005] The purpose of the present invention is to solve the above-mentioned deficiencies in the prior art and to provide a main circuit and working method of a marine constant frequency regulated power supply which has a simple structure, low cost, long service life, saves light oil, and effectively protects marine electrical appliances.

[0006] The technical solution adopted by the present invention to solve the above-mentioned deficiencies in the prior art is:

[0007] A main circuit of a marine constant frequency voltage-stabilized power supply comprises a rectifier circuit, a pre-charging circuit, an energy storage filter circuit, an inverter circuit and an output filter circuit, and is characterized in that a boost circuit is arranged between the pre-charging circuit and the energy storage filter circuit, the boost circuit is a DC-DC boost circuit composed of an inductor, an IGBT and a diode, an input protection circuit is arranged at the front end of the rectifier circuit, and the input protection circuit is composed of a fast fuse and a circuit breaker connected in series; a current sensor is arranged at the rear end of the boost circuit.

[0008] The rectifier circuit described in the present invention is a three-phase rectifier bridge circuit composed of diodes, and the pre-charging circuit is composed of a relay and a pre-charging resistor, and is located between the rectifier circuit and the boost circuit.

[0009] The energy storage filter circuit described in the present invention is arranged between the boost circuit and the inverter circuit. The filter circuit is composed of two capacitors connected in series, and the two capacitors are respectively connected in parallel with a voltage-equalizing resistor.

[0010] The two capacitors described in the present invention are capacitor groups formed by connecting at least two electrolytic capacitors in parallel.

[0011] The inverter circuit described in the present invention is an inverter bridge composed of IGBTs, and the inverter bridge is composed of four IGBT half-bridges; each half-bridge can be adjusted and controlled individually, and can output both three-phase power and single-phase power.

[0012] The output filter circuit described in the present invention is arranged at the rear end of the inverter bridge, and the output filter circuit is composed of four reactors and three capacitors. The four reactors are respectively connected to the A phase line, B phase line, C phase line and neutral line N of the four half-bridge outputs of the inverter circuit to filter the four half-bridge outputs of the inverter circuit, and the three capacitors are respectively connected between the A phase line, B phase line, C phase line and neutral line N at the rear side of the four reactors to filter the output single phase. The output filter circuit can improve the output voltage waveform, reduce the harmonic content, and improve the power quality. The three capacitors in the output filter are all connected to the N phase, so that each phase of the output three phases can work independently, so that the constant frequency regulated power supply can work normally when the three-phase load is unbalanced.

[0013] The working method of the main circuit of the above-mentioned ship-borne constant frequency and voltage-stabilized power supply is characterized in that the unstable power (frequency and voltage) emitted by the shaft-driven generator on the ship is rectified by the rectifier circuit to become a DC voltage, and the energy storage filter circuit is charged by the pre-charging circuit. After the whole system is stable, the relay of the pre-charging circuit is energized to short-circuit the pre-charging resistor, and the inverter circuit starts to work immediately to provide power for the electrical appliances on board; the DC bus voltage is detected in real time, and the DC bus voltage value detected in real time is compared with the DC bus voltage setting value. After the difference is adjusted by the PI regulator, a PWM duty cycle signal for driving the boost circuit IGBT is generated to increase the rectified voltage to the set value; the DC voltage value before boosting is calculated according to the detected DC bus voltage value, the DC current value detected by the current sensor and the PWM duty cycle. When the DC voltage value is higher than the set value, it is considered that the generator is in a fault state, and the circuit breaker is disconnected (controllably tripped) to protect the subsequent circuit; when the input is overcurrent, the fast fuse is blown to protect the shaft-driven generator, the constant frequency and voltage-stabilized power supply and the electrical equipment. When the relay of the pre-charging circuit is disconnected and high voltage is generated at the moment of power-on, the pre-charging resistor limits the charging current of the filter capacitor and protects the rectifier bridge.

[0014] When the present invention is used, the input end of the input protection circuit is connected to the shaft generator on the ship, and the relay of the pre-charging circuit, the current sensor, the IGBT of the boost circuit and the IGBT of the inverter circuit are respectively connected to the main controller; the present invention is controlled to work according to the above method to provide a safe and reliable power supply for the electrical appliances on board. The present invention has the advantages of simple structure, low cost, long service life, saving light oil, and effectively protecting the electrical appliances on board. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the circuit structure of the present invention. DETAILED DESCRIPTION

[0016] like Figure 1The main circuit of the marine constant frequency regulated power supply shown in the figure comprises a rectifier circuit 2, a pre-charging circuit 3, an energy storage filter circuit 5, an inverter circuit 6 and an output filter circuit 7 which are arranged in sequence. The rectifier circuit 2 is a three-phase rectifier bridge circuit composed of diodes. The pre-charging circuit 3 is composed of a relay and a pre-charging resistor R3 which are arranged in parallel. The normally open contacts of the relay are respectively connected to both ends of the pre-charging resistor R3. The pre-charging circuit 3 is arranged on the positive bus of the DC bus between the rectifier circuit 2 and the boost circuit 4. The filter circuit is composed of two capacitors C1 and C2 connected in series. The two capacitors C1 and C2 are respectively connected in parallel with equalizing resistors R1 and R2 with the same resistance value. The two capacitors C1 and C2 are respectively capacitor groups formed by connecting at least two electrolytic capacitors in parallel. The inverter circuit is an inverter bridge composed of IGBTs, and the inverter bridge is composed of four IGBT half-bridges. Each half-bridge can be adjusted and controlled individually to provide a stable neutral point N. The output ends of the four IGBT half-bridges are respectively connected to the A phase line, the B phase line, the C phase line and the neutral line N. The A phase line, the B phase line and the C phase line can constitute a three-phase power supply, and can also constitute a single-phase power supply with the N phase. The output filter circuit 7 is arranged at the rear end (output end) of the inverter bridge. The output filter circuit 7 is composed of four reactors L2, L3, L4, L5 and three capacitors C3, C4, C5. The four reactors L2, L3, L4, L5 are respectively connected in series to the A phase line, B phase line, C phase line and neutral line N of the four half-bridge outputs of the inverter circuit to filter the four half-bridge outputs of the inverter circuit. The three capacitors C3, C4, C5 are respectively connected between the A phase line, B phase line, C phase line and neutral line N on the rear side of the four reactors to filter the output single phase. The output filter circuit can improve the output voltage waveform, reduce the harmonic content, and improve the power quality. The three capacitors C3, C4, C5 in the output filter are all connected to the N phase, so that each phase of the output three phases can work independently, so that the constant frequency regulated power supply can work normally when the three-phase load is unbalanced. A boost circuit 4 is provided between the pre-charging circuit 3 and the energy storage filter circuit 5. The boost circuit 4 is a DC-DC boost circuit composed of an inductor L1, an IGBT and a diode D1. The inductor L1 of the boost circuit 4 is connected to the pre-charging circuit, and the diode D1 is connected to the energy storage filter circuit. An input protection circuit 1 is provided at the front end of the rectifier circuit 2. The input protection circuit 1 is composed of a fast fuse 8 and a controllable trip circuit breaker 9 connected in series. A current sensor CS1 is provided on the positive bus of the positive DC bus at the rear end of the boost circuit.

[0017] The working method of the main circuit of the above-mentioned ship-used constant frequency and voltage-stabilized power supply is characterized in that the unstable electricity (frequency and voltage) emitted by the shaft-driven generator on the ship is rectified by the rectifier circuit to become direct current, and the energy storage filter circuit is charged by the pre-charging circuit. After the whole system is stable, the relay of the pre-charging circuit is energized to short-circuit the pre-charging resistor, and the inverter circuit starts to work immediately to provide power for the electrical appliances on board; the DC bus voltage on both sides of the energy storage filter circuit is detected in real time, that is, the voltage between the positive bus and the negative bus of the DC bus on the rear side of the boost circuit; the DC bus voltage value detected in real time after the boost is compared with the set value of the DC bus voltage, and the difference is adjusted by the PI regulator to generate a PWM duty cycle signal of the T1 tube of the IGBT of the driving boost circuit, and the rectified voltage is increased to the set value; when the diesel main engine speed is low or idling and the output voltage of the shaft-driven generator is low, the boost circuit can still provide the subsequent inverter circuit and the load with a voltage amplitude that meets the requirements, and when the power consumption of the ship can be met, there is no need to start the auxiliary engine to generate electricity. According to the detected DC bus voltage value, the DC current value detected by the current sensor CS1 and the PWM duty cycle, the DC voltage value before the boost is calculated. If the DC voltage value is higher than the set value, it is considered that the generator is in a fault state, and the controllable trip circuit breaker is disconnected to protect the subsequent circuit; when the input is overcurrent, the fast fuse blows to protect the shaft generator, constant frequency regulated power supply and electrical equipment. When the relay of the pre-charging circuit is disconnected and high voltage is generated at the moment of power-on, the pre-charging resistor limits the charging current of the filter capacitor, protects the rectifier bridge and prolongs its service life.

[0018] When the present invention is used, the input end of the input protection circuit is connected to the shaft generator on the ship, the output end of the output filter circuit is connected to the electrical equipment on the ship to supply power to it, the relay of the pre-charging circuit, the current sensor, the IGBT of the boost circuit and the IGBT of the inverter circuit are respectively connected to the main controller; the present invention is controlled to work according to the above method to provide a safe and reliable power supply for the electrical appliances on board. The present invention has the advantages of simple structure, low cost, long service life, saving light oil, and effectively protecting the electrical appliances on board.

Claims

1. A main circuit of a marine constant frequency and voltage stabilizing power supply, comprising a rectifier circuit, a pre-charging circuit, an energy storage filter circuit, an inverter circuit and an output filter circuit arranged in sequence, wherein the rectifier circuit is a three-phase rectifier bridge circuit composed of diodes, the pre-charging circuit is composed of a relay and a pre-charging resistor R3 arranged in parallel, the normally open contacts of the relay are respectively connected to both ends of the pre-charging resistor R3, and the pre-charging circuit is arranged on the positive bus of the DC bus between the rectifier circuit and the boost circuit; the filter circuit is composed of two capacitors C1 and C2 connected in series , the two capacitors C1 and C2 are respectively connected in parallel with equalizing resistors R1 and R2 with the same resistance value, and the two capacitors C1 and C2 are respectively capacitor groups formed by connecting at least two electrolytic capacitors in parallel; the inverter circuit is an inverter bridge composed of IGBTs, and the inverter bridge is composed of four IGBT half-bridges; the output ends of the four IGBT half-bridges are respectively connected to the A phase line, the B phase line, the C phase line and the neutral line N, and the A phase line, the B phase line, and the C phase line constitute a three-phase power supply or respectively constitute a single-phase power supply with the neutral line N; the output filter circuit is arranged at the inverter At the rear end of the variable bridge, the output filter circuit is composed of four reactors L2, L3, L4, L5 and three capacitors C3, C4, C5. The four reactors L2, L3, L4, L5 are respectively connected in series to the A phase line, B phase line, C phase line and neutral line N of the four half-bridge outputs of the inverter circuit to filter the four half-bridge outputs of the inverter circuit. The three capacitors C3, C4, C5 are respectively connected between the A phase line, B phase line, C phase line and neutral line N on the rear side of the four reactors to filter the output single phase; the three capacitors C3, C4 and C5 are both connected to the neutral line N; a boost circuit is provided between the pre-charging circuit and the energy storage filter circuit, and the boost circuit is a DC-DC boost circuit composed of an inductor L1, an IGBT and a diode D1, the inductor L1 of the boost circuit is connected to the pre-charging circuit, and the diode D1 is connected to the energy storage filter circuit; an input protection circuit is provided at the front end of the rectifier circuit, and the input protection circuit is composed of a fast fuse and a controllable trip circuit breaker connected in series; a current sensor CS1 is provided on the positive bus of the positive DC bus at the rear end of the boost circuit.

2. The working method of the main circuit of the marine constant frequency regulated power supply according to claim 1, characterized in that: The unstable electricity generated by the shaft generator on the ship is rectified by the rectifier circuit and converted into a DC voltage. The energy storage filter circuit is charged by the pre-charging circuit. After the whole system is stable, the relay of the pre-charging circuit is energized to short-circuit the pre-charging resistor, and the inverter circuit starts working immediately to provide power for the electrical appliances on board. The DC bus voltage is detected in real time, and the real-time detected DC bus voltage value is compared with the DC bus voltage setting value. The difference is adjusted by the PI regulator to generate a PWM duty cycle signal for driving the boost circuit IGBT, and the rectified voltage is increased to the set value. The DC voltage value before the boost is calculated based on the detected DC bus voltage value, the DC current value detected by the current sensor, and the PWM duty cycle. When the DC voltage value is higher than the set value, it is determined that the generator is in a fault state, and the circuit breaker is disconnected to protect the subsequent circuit. When the input is overcurrent, the fast fuse is blown to protect the shaft generator, constant frequency voltage-stabilized power supply and electrical equipment.

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