Three-level rectifier of parallel single-tube bidirectional switch
Technical Field
The invention relates to a three-level rectifier, in particular to a three-level rectifier of a parallel single-tube bidirectional switch.
Background
In the past decade, high voltage, high power, multi-level conversion technology has become a focus and focus of research due to its rapid development and widespread use. In the high-voltage large-capacity field, due to the fact that the development and research in foreign countries are mature, a lot of documents and data about high-voltage high-power multi-level technology are accumulated. With the wide application of high-voltage large-capacity multi-level technology in the industrial field, the domestic demand for high-voltage large-power multi-level technology is more and more strong, which promotes the wide research and rapid development of multi-level conversion technology in China and obtains a plurality of valuable scientific achievements.
Disclosure of Invention
The invention provides a three-level rectifier of a parallel single-tube bidirectional switch, which is a rectifier with higher voltage grade formed by switching tubes with lower voltage grade.
The technical scheme adopted by the invention is as follows:
a three-level rectifier of a parallel single-tube bidirectional switch, the rectifier comprising:
power switch tube S1、S2Inductor L, diode D1~D12A voltage dividing capacitor C1、C2;
One end of an Alternating Current (AC) power supply is connected with one end of the inductor L;
the other end of the inductor L is respectively connected with a diode D2Anode, diode D3A cathode, the connection point of which constitutes node a;
diode D2The cathodes are respectively connected with a diode D1Anode and power switch tube S1Drain electrode, diode D5A cathode;
diode D3The anodes are respectively connected with a diode D4Cathode, power switch tube S1A source electrode; diode D6An anode;
diode D5The anodes are respectively connected with a diode D6Cathode, diode D8Anode, diode D9The other end of the cathode and the other end of the alternating current power supply AC, and the connection point of the cathode and the other end of the alternating current power supply AC forms a node b;
diode D8The cathodes are respectively connected with a diode D7Anode and power switch tube S2Drain electrode, diode D11A cathode;
diode D9The anodes are respectively connected with a diode D10Cathode, power switch tube S2Source, diode D12An anode;
diode D1The cathodes are respectively connected with a diode D7Cathode and voltage-dividing capacitor C1One end, the connection point of which constitutes a node p;
diode D4The anodes are respectively connected with a diode D10Anode and voltage-dividing capacitor C2The other end, the connection point of which forms a node m;
diode D11The anodes are respectively connected with a diode D12Cathode and voltage-dividing capacitor C1Another terminal, a voltage-dividing capacitor C2One end, the connection point of which constitutes node n;
load RLThe two ends are respectively connected with the node p and the node m.
In the rectifier, a diode D1Diode D2Diode D3Diode D4Diode D5Diode D6Power switch tube S1A group of single-tube bidirectional switches are formed to provide a charging loop for the inductor L;
diode D7Diode D8Diode D9Diode D10Diode D11Diode D12Power switch tube S2Another group of single-tube bidirectional switches is formed as a voltage-dividing capacitor C1、C2A charge and discharge circuit is provided.
In the rectifier, powerSwitch tube S1、S2Are insulated gate bipolar transistors IGBT, or integrated gate commutated thyristors IGCT, or power field effect transistors MOSFET.
The invention discloses a three-level rectifier of a parallel single-tube bidirectional switch, which has the following technical effects:
1) the three-level rectifier of the parallel single-tube bidirectional switch uses the switch tubes with lower voltage grade to form the rectifier with higher voltage grade. Because each switching tube in the main circuit bears half of the direct current bus voltage when being turned off, the direct current side voltage can be doubled under the condition that the withstand voltage level of the power device is the same, and the high-voltage direct current bus voltage doubling circuit is suitable for medium-high voltage large-capacity power application occasions.
2) According to the three-level rectifier of the parallel single-tube bidirectional switch, the alternating-current side voltage is three-level step waves, the shape is closer to a sine wave relative to three levels of a two-level topology, and harmonic waves are much lower than the two levels under the same switching frequency. Thus, the higher harmonics of the input current of a three-level rectifier are much smaller than those of a two-level rectifier.
3) The three-level rectifier of the parallel single-tube bidirectional switch can ensure a certain sine degree even if the input side current waveform has lower switching frequency, which is just suitable for the requirement that the switching frequency of a high-voltage large-capacity power electronic device can not be too high due to the problems of switching loss and device performance and can run at an approximate unit power factor.
4) Under the condition that the switching frequency and the control mode are completely the same, compared with a two-level rectifier, the three-level rectifier of the parallel single-tube bidirectional switch has much lower harmonic content of the network side current, so that the required filtering inductance value of the alternating current side is greatly reduced, and the system cost is reduced.
Drawings
Fig. 1 is a main topology structure diagram of a three-level rectifier of a parallel single-tube bidirectional switch of the invention.
Fig. 2 is a schematic diagram of a working mode of a three-level rectifier of the parallel single-tube bidirectional switch according to the present invention.
Fig. 3 is a schematic diagram of a working mode two of a three-level rectifier of the parallel single-tube bidirectional switch of the invention.
Fig. 4 is a three-schematic diagram of the working mode of the three-level rectifier of the parallel single-tube bidirectional switch of the invention.
Fig. 5 is a diagram of the four working modes of the three-level rectifier of the parallel single-tube bidirectional switch of the invention.
Fig. 6 is a five schematic diagram of the working mode of the three-level rectifier of the parallel single-tube bidirectional switch of the invention.
Fig. 7 is a six schematic diagram of the working mode of the three-level rectifier of the parallel single-tube bidirectional switch of the invention.
FIG. 8 shows the AC power supply voltage u of the three-level rectifier of the parallel single-tube bidirectional switch of the present inventionsAnd alternating supply current isAnd (4) waveform diagrams.
FIG. 9 shows the voltage u between the point a and the point b of the three-level rectifier of the parallel single-tube bidirectional switch according to the present inventionabAnd (4) waveform diagrams.
FIG. 10 shows the DC side voltage u of the three-level rectifier of the parallel single-tube bidirectional switch of the present inventiondcAnd (4) waveform diagrams.
FIG. 11 shows a DC-side voltage-dividing capacitor C of a three-level rectifier of a parallel single-tube bidirectional switch according to the present invention1And a voltage-dividing capacitor C2Voltage u ondc1、udc2And (4) waveform diagrams.
Detailed Description
As shown in FIG. 1, a three-level rectifier with parallel single-tube bidirectional switches comprises two groups of single-tube bidirectional switches, and a voltage-dividing capacitor C1A voltage dividing capacitor C2。
Wherein, a group of single-tube bidirectional switches consists of a diode D1Diode D2Diode D3Diode D4Diode D5Diode D6Power switch tube S1Forming;
another group of single-tube bidirectional switches is composed of a diode D7Diode D8Diode D9Diode D10Diode D11Diode D12Power switch tubeS2And (4) forming.
Diode D2Anode of (2), diode D3The cathode and the inductor L are connected with a point a; diode D5Anode of (2), diode D6Cathode of (2), diode D8Anode of (2), diode D9One end of the cathode and one end of the alternating current power supply AC are connected with a point b;
diode D1Cathode of (2), diode D5Cathode and voltage-dividing capacitor C1The positive electrode of (2) is connected with the point p;
diode D11Anode of (2), diode D12Cathode and voltage-dividing capacitor C1Negative electrode of (1), voltage-dividing capacitor C2The positive electrode of (2) is connected with the n point;
diode D4Anode of (2), diode D10Anode and voltage-dividing capacitor C2The negative electrode of (2) is connected with the m point; diode D1Anode of (2), diode D2Cathode of (2), diode D5Cathode of (2), power switch tube S1Is connected to the drain of the diode D3Anode of (2), diode D4Cathode of (2), diode D6Anode of (2), power switch tube S1Is connected to the source of a diode D7Anode of (2), diode D8Cathode of (2), diode D11Cathode of (2), power switch tube S2Is connected to the drain of the diode D9Anode of (2), diode D10Cathode of (2), diode D12Anode of (2), power switch tube S2Is connected with the source electrode of the alternating current power supply AC, the other end of the alternating current power supply AC is connected with the inductor L, and the load RLConnected between the p-point and the m-point.
usIs an AC supply voltage isIs an alternating supply current uabIs the voltage between point a and point b, udcIs a DC side voltage udc1And udc2Are respectively a DC side voltage-dividing capacitor C1And a voltage-dividing capacitor C2Upper voltage, dividing capacitor C1And a voltage-dividing capacitor C2The voltage of the direct current side is stabilized together, and meanwhile, the electric energy can be stored to the load RLProviding energy.
The specific parameters of the circuit are as follows: AC power supplyPress usHas an effective value of 220V, a frequency of 50Hz, and a DC side output voltage udc400V, 2.6mH, voltage-dividing capacitor C1=C24700 μ F, switching frequency Fs20kHz, load RL=80Ω。
The invention relates to a three-level rectifier of a parallel single-tube bidirectional switch, which divides the whole power frequency working period into six working modes according to a Pulse-Width Modulation (PWM) strategy of carrier lamination:
the first working mode is as follows: diode D operating in the positive half-cycle of the AC supply1Diode D2Diode D9Diode D10Conducting power switch tube S1Power switch tube S2And (5) disconnecting. The current starts from an alternating current power supply AC and passes through an inductor L and a diode D2Diode D1 and voltage-dividing capacitor C1And a voltage-dividing capacitor C2Diode D10Diode D9And finally back to the AC power source AC. In this mode of operation, the voltage u between the points a and babEqual to the DC side voltage udcA voltage dividing capacitor C1And a voltage-dividing capacitor C2Charging, AC power supply AC and inductance L together giving load RLSupplying power, and linearly reducing the current of the inductor L;
the second working mode is as follows: diode D operating in the positive half-cycle of the AC supply1Diode D2Diode D9Diode D11Conducting power switch tube S2Conducting power switch tube S1And (5) disconnecting. The current starts from an alternating current power supply AC and passes through an inductor L and a diode D2Diode D1 and voltage-dividing capacitor C1Diode D11Power switch tube S2Diode D9And finally back to the AC power source AC. In this mode of operation, the voltage u between the points a and babEqual to the DC side voltage udcHalf of (1), voltage dividing capacitor C1Charging and voltage-dividing capacitor C2Discharging if the AC supply voltage usHigher than udcAt/2, in this state, the inductor L current rises linearly if the AC supply voltage usLess than udcAt/2, in this state, the inductor L current drops linearly;
the working mode is three: diode D operating in the positive half-cycle of the AC supply2Diode D6Conducting power switch tube S1Conducting power switch tube S2And (5) disconnecting. The current starts from an alternating current power supply AC and passes through an inductor L and a diode D2Power switch tube S1Diode D6And finally back to the AC power source AC. In this mode of operation, the voltage u between the points a and babZero, voltage-dividing capacitor C1And a voltage-dividing capacitor C2Common discharge to the load RLCharging energy, wherein an alternating current power supply AC charges an inductor L;
working mode four: diode D operating in the negative half-cycle of the AC supply3Diode D5Conducting power switch tube S1Conducting power switch tube S2Is disconnected and current flows from the AC power supply AC through the diode D5Power switch tube S1Diode D3Inductor L and finally back to the AC power supply AC. In this mode of operation, the voltage u between the points a and babZero, voltage-dividing capacitor C1And a voltage-dividing capacitor C2Common discharge to the load RLCharging energy, wherein an alternating current power supply AC charges an inductor L;
working mode five: diode D operating in the negative half-cycle of the AC supply3Diode D4Diode D8Diode D12Conducting power switch tube S2Conducting power switch tube S1Is disconnected and current flows from the AC power supply AC through the diode D8Power switch tube S2Diode D12And a voltage-dividing capacitor C2Diode D4Diode D3Inductor L and finally back to the AC power supply AC. In this mode of operation, the voltage u between the points a and babEqual to negative DC side voltage udcHalf of (1), voltage dividing capacitor C1Discharging, voltage dividing capacitor C2Charging if the AC supply voltage usIs higher than udcAt/2, in this state, the L current of the inductor is linearRising; if the AC supply voltage usIs less than udcAt/2, in this state, the inductor L current drops linearly;
the working mode is six: diode D operating in the negative half-cycle of the AC supply3Diode D4Diode D7Diode D8Conducting power switch tube S1Power switch tube S2Is disconnected and current flows from the AC power supply AC through the diode D8Diode D7And a voltage-dividing capacitor C1And a voltage-dividing capacitor C2Diode D4Diode D3Inductor L and finally back to the AC power supply AC. In this mode of operation, the voltage u between the points a and babEqual to negative DC side voltage udcA voltage dividing capacitor C1And a voltage-dividing capacitor C2Charging, AC power supply AC and inductance L together giving load RLWhen power is supplied, the current of the inductor L is linearly reduced.
FIG. 8 shows the AC power supply voltage u of the three-level rectifier of the parallel single-tube bidirectional switch of the present inventionsAnd alternating supply current isThe waveform diagram, the network side voltage and the current have the same frequency and the same phase, namely the unit power factor is realized, and the feasibility of the topology is proved.
FIG. 9 shows the voltage u between the a point and the b point of the three-level rectifier of the parallel single-tube bidirectional switch according to the present inventionabThe oscillogram accords with the working characteristics of the three-level circuit and is consistent with theoretical analysis.
FIG. 10 shows the DC side voltage u of the three-level rectifier of the parallel single-tube bidirectional switch of the present inventiondcThe waveform diagram shows that the voltage on the direct current side is stabilized to be about 400V, and the feasibility of the topology is proved.
FIG. 11 shows a DC-side voltage-dividing capacitor C of a three-level rectifier of a parallel single-tube bidirectional switch according to the present invention1And a voltage-dividing capacitor C2Voltage u ondc1、udc2The waveform diagram and the voltage waveform of the two voltage-dividing capacitors are dynamically balanced, and the fact that the topology effectively achieves midpoint potential balance is proved.