CN1780132A - Inverter circuit and its inverter method - Google Patents

Abstract

An inverter is composed of the 1st and the 2nd charging capacitors, the 1st and the 4th switch transistors, the 1st and the 2nd filter inductors, filter capacitor, and the 2nd and the 3rd one-way switch transistors. Its circuit or inverting method is also disclosed.

Description

Inverter circuit and its inverter method

【Technical field】

The invention relates to an inverter circuit and an inverter method thereof.

【Background technique】

Current inverter topologies are usually of two types: two-level and three-level.

The two-level topology is relatively common and widely used. Figure 1 shows the commonly used two-level inverter topology. When the switch tube Q1 is working and the switch tube Q4 is not working, a positive half wave of the sine wave is generated; the switch tube Q4 is working, the switch When the tube Q1 is not working, it produces the negative half wave of the sine wave. The advantage of this topology is that the control is simple, the output sine wave waveform has little distortion, and the response is fast. However, the voltage at point B6 at the second end of the switch tube Q1 is positive and negative, which requires a high withstand voltage of the switch tube, and a switch tube with high withstand voltage must be used, and the loss of the switch tube is also large; and because the output PWM Wave harmonics are rich, so the required filter inductance is larger. In order to reduce the switch tube withstand voltage and filter inductance, a freewheeling circuit is added on the basis of the two-level inverter topology to form a three-level inverter topology, as shown in Figures 2 and 3, so that the second terminal of the switch tube Q1 The voltage at point B6 changes from positive and negative two levels to positive, zero and negative three levels, so that the voltage change at both ends of the switch tube is relatively small, the voltage stress is only half of the original, the switching loss is less than the two levels, and due to the output The harmonics of the PWM wave are smaller than those of the two levels, so the filter inductance is smaller than that of the two levels. However, the existing three-level topology has the following disadvantages: 1) The control is relatively complicated, requiring PWM waves to control four switching tubes. 2) The output sine wave responds slower than the two-level output sine wave. The drop rate of the current in the filter inductor is related to the voltage across the filter inductor, that is, U=L*di/dt. The freewheeling circuit of the two-level inverter topology carries out freewheeling through a circuit including a filter capacitor and a charging capacitor. The voltage across the filter inductor is the instant voltage of the filter capacitor plus the voltage across the charging capacitor, and the current change rate di/dt larger. However, the freewheeling circuit of the three-level inverter topology only passes through the filter capacitor and does not pass through the charging capacitor, so the voltage across the filter inductor is only the instant voltage of the filter capacitor, and the current change rate di/dt is smaller than that of the two-level inverter topology. slow response.

【Content of invention】

The main purpose of the present invention is to solve the problems in the prior art and provide an inverter circuit, which has the advantages of the two-level inverter topology and the three-level inverter topology.

Another object of the present invention is to solve the problems in the prior art and provide an inverter method using the above inverter circuit, which has the advantages of both the two-level inverter topology and the three-level inverter topology.

In order to achieve the above object, an inverter circuit proposed by the present invention includes a first charging capacitor, a second charging capacitor, a first switching tube, a fourth switching tube and a filter capacitor, the first charging capacitor and the second charging capacitor series connection; it also includes a first filter inductance, a second filter inductance, a second switch tube for one-way conduction and a third switch tube for one-way conduction; the first switch tube is connected to the positive terminal of the first charging capacitor and the first filter tube Between the input terminals of the inductance, the conduction or disconnection is controlled by a PWM wave; the output terminal of the first filter inductor is connected to the first end of the filter capacitor; the second end of the filter capacitor is connected to the first charging capacitor It is connected to the central point of the series connection of the second charging capacitor; the fourth switching tube is connected between the negative terminal of the second charging capacitor and the output terminal of the second filter inductor, and is turned on or off by PWM wave control; the second The input end of the filter inductor is connected to the first end of the filter capacitor; the second switch tube is connected between the input end of the first filter inductor and the second end of the filter capacitor, and the third switch tube is connected to the output of the second filter inductor terminal and the second terminal of the filter capacitor.

The first switch tube and the fourth switch tube are IGBTs.

As a further improvement of the present invention, the characteristics of the first filter inductor and the second filter inductor are the same.

A further improvement of the present invention is to add a discharge branch. The discharge branch includes a first discharge branch for releasing the stored energy of the first filter inductance and a second discharge branch for releasing the stored energy of the second filter inductance, the first discharge branch is connected to the Between the input terminal of a filter inductor and the negative terminal of the second charging capacitor, the second discharge branch is connected between the output terminal of the second filter inductor and the positive terminal of the first charging capacitor.

In order to achieve the above object, the present invention also provides an inverter method for the above inverter circuit: during the generation of the sine wave, the first switching tube and the fourth switching tube work complementary; during the positive half cycle of the sine wave generation, the first switching tube The second switching tube is turned on, and the third switching tube is turned on during the negative half period of the sine wave generation; the current flowing through the first filter inductor and the current flowing through the second filter inductor are superposed at the first end of the filter capacitor.

The further improvement of the present invention is to increase the discharge branch. The discharge branch includes a first discharge branch for releasing the stored energy of the first filter inductance and a second discharge branch for releasing the stored energy of the second filter inductance, the first discharge branch is connected to the Between the input terminal of a filter inductor and the negative terminal of the second charging capacitor, the second discharge branch is connected between the output terminal of the second filter inductor and the positive terminal of the first charging capacitor. During the positive half cycle of sine wave generation, when the third switch tube and the fourth switch tube are turned off at the same time, the energy on the second filter inductance is transferred to the first charging capacitor through the second discharge branch; when the sine wave is generated During the negative half cycle of , when the first switching tube and the second switching tube are turned off at the same time, the energy on the first filter inductor is transferred to the second charging capacitor through the first discharge branch.

The beneficial effects of the present invention are: 1) The voltage stress of the switch device in this scheme is small, the switching loss is small, and the efficiency is high, and general devices with lower withstand voltage can be used instead of expensive high withstand voltage devices. It is especially suitable for converters with higher output voltage and saves cost. The output is two-level effect, fast response, and small waveform distortion. 2) The second switching tube S2 and the third switching tube S3 only switch once in half a cycle, which reduces switching loss. 3) The present invention increases the discharge branch, so that when the second switch tube S2 or the third switch tube S3 is turned off, the first filter inductance L1-1 or the second filter inductance L1-2 can be released through the discharge branch. Energy storage reduces damage to the switch tube. 4) The present invention can freely switch between three levels and two levels in the control mode, so as to realize flexible control. When the second switching tube S2 and the third switching tube S3 are turned on at the same time, it is a two-level inverter circuit. 5) The present invention can also utilize three identical circuits to form a three-phase inverter, and each single phase has the above effects.

The features and advantages of the present invention will be described in detail with reference to the accompanying drawings.

【Description of drawings】

FIG. 1 shows a two-level inverter topology in the prior art;

FIG. 2 shows a three-level inverter topology in the prior art;

Fig. 3 shows another three-level inverter topology in the prior art;

Fig. 4 shows the schematic diagram of the BUCK converter of the positive half wave of the sine wave;

Fig. 5 shows the schematic diagram of the BUCK converter of the negative half-wave of the sine wave;

Fig. 6 represents a schematic diagram of the present invention;

Fig. 7 represents the driving wave diagram of each switch of the present invention;

Fig. 8 represents the circuit diagram of the first form of an embodiment of the present invention;

Fig. 9 represents the circuit diagram of the second form of an embodiment of the present invention;

Fig. 10 shows the circuit diagram of the present invention to form three-phase output.

【Detailed ways】

Specific Embodiment 1. This embodiment mainly includes two charging loops. The first charging loop is composed of a first charging capacitor C1, a first switching tube S1, a second switching tube S2, a first filter inductor L1-1 and a filter capacitor C. ,As shown in Figure 4. The second charging loop is composed of the second charging capacitor C2, the fourth switch tube S4, the third switch tube S3, the second filter inductor L1-2 and the filter capacitor C, as shown in FIG. 5 . When the fourth switching tube S4 and the third switching tube S3 are disconnected, and the second switching tube S2 and the first switching tube S1 work together, it is equivalent to a BUCK converter with only one positive half-wave. The first charging circuit is formed from the positive terminal B3 of the first charging capacitor C1 through the first switching tube S1, the first filter inductor L1-1 and the filter capacitor C, and then to the negative terminal B4 of the first charging capacitor C1. A load is connected to both ends of the filter capacitor C, so that the filter capacitor C and the load form a discharge circuit, and the combination of the first charge circuit and the discharge circuit generates a positive half wave of a sine wave. The second switch tube S2 serves as a freewheeling branch of the first filter inductor L1-1. Therefore, a positive half-cycle PWM wave is generated at the second terminal B1 of the first switching tube S1, and the level changes from positive to zero, and is filtered by LC to form a positive half-sine wave. When the first switching tube S1 and the second switching tube S2 are disconnected, and the third switching tube S3 and the fourth switching tube S4 work together, it is equivalent to a BUCK converter with only negative half-wave. The second charging loop is formed from the positive terminal B4 of the second charging capacitor C2 through the filter capacitor C, the second filter inductor L1-2 and the fourth switching tube S4, and then to the negative terminal B5 of the second charging capacitor C2. The second charge circuit and discharge circuit combine to generate the negative half wave of the sine wave. The third switch tube S3 serves as a freewheeling branch of the second filter inductor L1-2. Therefore, a negative half cycle PWM wave is generated at the second terminal B2 of the fourth switch tube S4, and the level is from zero to negative.

The buck converter of the positive half wave and the buck converter of the negative half wave work alternately, and the positive and negative half waves of the sine wave are combined to form a sine wave. Because the second terminal B1 of the first switch tube S1 generates a PWM wave from positive to zero, and the second terminal B2 of the fourth switch tube S4 produces a PWM wave from zero to negative, so the switching tubes of the combined circuit The withstand voltage is small, and the output PWM wave harmonics are less than those of two levels, so the filter inductance is smaller than that of two levels.

As shown in Figure 6, the first charging capacitor C1 and the second charging capacitor C2 are connected in series, starting from the positive terminal B3 of the first charging capacitor C1, the first switching tube S1, the first filter inductor L1-1, and the filter capacitor are serially connected in series. C, and then to the series center point B4 of the first charging capacitor C1 and the second charging capacitor C2, the second switching tube S2 is connected between the input terminal of the first filter inductor L1-1 and the second terminal of the filter capacitor C. Starting from the negative terminal B5 of the second charging capacitor C2, the fourth switch tube S4, the second filter inductor L1-2, and the filter capacitor C are serially connected in series, and then to the central point of the series connection between the first charging capacitor C1 and the second charging capacitor C2 B4, the third switch tube S3 is connected between the output end of the second filter inductor L1-2 and the second end of the filter capacitor C. Connect loads in parallel at both ends of the filter capacitor C.

During the working process, the voltage stress of the first switching tube S1 and the fourth switching tube S4 is half of the sum of the voltages across the first charging capacitor C1 and the second charging capacitor C2, so general switching tubes can be used, usually IGBT , and its connections are shown in Figures 8 and 9. The first switching tube S1 is a first IGBT (insulated gate bipolar transistor), the gate of the first IGBT receives a PWM wave signal to control the operation of related devices, and the source is connected to the positive terminal B3 of the first charging capacitor C1 The drain is connected to the input terminal of the first filter inductor L1-1; the fourth switching tube S4 is the fourth IGBT, the gate of the fourth IGBT receives the PWM wave signal to control the action of related devices, and the source It is connected to the output terminal of the second filter inductor L1-2, and the drain is connected to the negative terminal B5 of the second charging capacitor C2.

The characteristics of the first filter inductance L1-1 and the second filter inductance L1-2 are the same, and the circuit is controlled according to two levels, so that the first switch tube S1 and the fourth switch tube S4 are controlled by the PWM wave to work in a complementary and symmetrical manner. The drive waveform is shown in Figure 7. In order to further simplify the control of the second switching tube S2 and the third switching tube S3 and reduce switching loss, both the second switching tube S2 and the third switching tube S3 are controllable switches. When the positive half wave of the sine wave is to be generated, the first switch tube S1 and the second switch tube S2 work together, and when the first switch tube S1 is turned on under the control of the PWM wave, the fourth switch tube S4 is controlled by the PWM wave to turn off; The second switching tube S2 is controlled by the low frequency, and a positive trigger voltage is applied to the control pole. The third switching tube S3 is controlled by the low frequency, and the trigger voltage is not applied to the control pole, and is in an off state. The voltage at both ends of the first charging capacitor C1 forms a loop through the first switch tube S1, the first filter inductor L1-1 and the filter capacitor C, and the current flows from the positive terminal B3 of the first charging capacitor C1 through the first switch tube S1, the first filter capacitor C1 and the first switch tube S1. A filter inductor L1-1 and a filter capacitor C, and then to the central point B4 of the series connection of the first charging capacitor C1 and the second charging capacitor C2. When the first switch S1 is turned off and the fourth switch S4 is turned on, since the current of the first filter inductor L1-1 cannot change abruptly, the first filter inductor L1-1 is equivalent to a current source at this time, and the filter capacitor C The connected end is high potential, and the end connected to the second switch tube S2 is low potential, so that a forward voltage is applied to both ends of the second switch tube S2, so that the second switch tube S2 is turned on under this condition, as the first switch tube S2 A freewheeling branch of the filter inductor L1-1. At the same time, another loop is formed, that is, the voltage across the second charging capacitor C2 forms another loop through the fourth switch tube S4, the second filter inductor L1-2 and the filter capacitor C, and the current is charged by the first charging capacitor C1 and the second The series center point B4 of the capacitor C2 flows through the filter capacitor C, the second filter inductor L1-2 and the fourth switch S4, and then reaches the negative terminal B5 of the second charging capacitor C2. The two currents are superimposed at Vout. By modulating and controlling the PWM waves of the first switching tube S1 and the fourth switching tube S4, the voltage at the second terminal B1 of the first switching tube S1 is:

$\mathrm{<span\; class="notranslate">\; vs.</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&omega;<figure-callout\; id="2"\; label="t"\; filenames="A20041009486100121.png,A20041009486100131.png"\; state="\{\{state\}\}">t</figure-callout></span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}$

The voltage at the second terminal B2 of the fourth switching tube S4 is:

$\mathrm{<span\; class="notranslate">\; vs.</span>}\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="A"\; filenames="A20041009486100121.png,A20041009486100123.png"\; state="\{\{state\}\}">A</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&omega;<figure-callout\; id="2"\; label="t"\; filenames="A20041009486100121.png,A20041009486100131.png"\; state="\{\{state\}\}">t</figure-callout></span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}$

After passing through the inductor, the PWM waves at points B1 and B2 become current sources. The current flowing through the first filter inductor L1-1 is Asinωt+X, and the current flowing through the second filter inductor L1-2 is X. The two currents Superimpose at Vout, because the current of the first filter inductor L1-1 flows in, and the current of the second filter inductor L1-2 flows out, so the two currents are subtracted, and the subtracted current is Asinωt, and the current is equivalent to The internal resistance is multiplied to get the Vout voltage:

Vo＝A ₂ sinωt

This produces the positive half of the sine wave. Wherein, A, A ₁ , A ₂ are coefficients related to the voltages of the first power supply and the second power supply, ω is the angular frequency of the output sine wave, t is a time parameter, and X is any constant greater than 0.

When the negative half wave of the sine wave is to be generated, when the fourth switch tube S4 is turned on under the control of the PWM wave, the first switch tube S1 is controlled by the PWM wave to turn off, the second switch tube S2 is controlled by the low frequency, and no The trigger voltage, the third switch tube S3 is controlled by low frequency, and a positive trigger voltage is applied to the control pole. The voltage across the second charging capacitor C2 forms another loop through the fourth switch tube S4, the second filter inductor L1-2 and the filter capacitor C, and the current flows from the central point B4 of the series connection between the first charging capacitor C1 and the second charging capacitor C2 After passing through the filter capacitor C, the second filter inductor L1-2 and the fourth switch tube S4, it reaches the negative terminal B5 of the second charging capacitor C2. When the fourth switching tube S4 is turned off, the first switching tube S1 is turned on. Since the current of the second filter inductor L1-2 cannot change abruptly, the third switch tube S3 forms a freewheeling branch under the drive of the second filter inductor L1-2. At the same time, another loop is formed, that is, the voltage at both ends of the first charging capacitor C1 forms a loop through the first switch tube S1, the first filter inductor L1-1 and the filter capacitor C, and the current flows from the positive terminal B3 of the first charging capacitor C1. Through the first switch tube S1, the first filter inductor L1-1 and the filter capacitor C, and then to the central point B4 of the series connection of the first charging capacitor C1 and the second charging capacitor C2. By modulating and controlling the PWM waves of the first switching tube S1 and the fourth switching tube S4, the current flowing through the first filter inductor L1-1 is X, and the current flowing through the second filter inductor L1-2 is Asinωt+X, both A current is superimposed at Vout as -Asinωt, and the current is multiplied by the equivalent internal resistance to obtain the Vout voltage:

Vo＝-A ₂ sinωt

This produces the negative half of the sine wave. The two half-waves are combined into a whole sine wave, and it has a two-level output effect, with little waveform distortion and fast response. The second switching tube S2 and the third switching tube S3 only switch once in half a cycle, which can reduce switching loss.

When the positive half wave of the sine wave is generated, the conduction of the fourth switch tube S4 releases the reactive energy on the filter capacitor C, and a falling wave is generated, so that the drop rate of the current in the first filter inductor L1-1 Increase. Similarly, when the negative half-wave of the sine wave is generated, the conduction of the first switch tube S1 releases the reactive energy on the filter capacitor C, and generates a falling wave, so that the current in the second filter inductor L1-2 The decrease rate is increased, so that the output waveform is less distorted and the response is faster.

How to modulate the PWM wave for controlling the current is known to those skilled in the art and will not be described here.

Specific embodiment 2. Since the first switching tube S1 and the fourth switching tube S4 work in a complementary manner, when the positive half wave of the sine wave is generated, there is still energy stored in the second filter inductor L1-2, but this At this time, the third switch tube S3, which is the freewheeling branch of the second filter inductor L1-2, is in the off state, and when the fourth switch tube S4 is also in the off state, the temporary energy storage in the second filter inductor L1-2 If it is not released, the second filter inductor L1-2 becomes a current source, applying high voltage to the third switching tube S3 and the fourth switching tube S4, causing damage to the switching tubes. Similarly, when the negative half-wave of the sine wave is generated, the temporary energy stored in the first filter inductor L1-1 cannot be released, causing damage to the first switching tube S1 and the second switching tube S2. This specific embodiment is an improvement on the specific embodiment 1, and a discharge branch is added, and the discharge branch includes a first discharge branch for releasing the stored energy of the first filter inductor L1-1 and a discharge branch for A second discharge branch for releasing the energy stored in the second filter inductor L1-2, the first discharge branch is connected to the input terminal of the first filter inductor L1-1 and the negative terminal of the second charging capacitor C2 Between, the second discharge branch is connected between the output terminal of the second filter inductor L1-2 and the positive terminal of the first charging capacitor C1. In this embodiment, the first discharge branch and the second discharge branch are realized by the first diode D1 and the second diode D2 respectively, and the cathode of the first diode D1 is connected to the first filter inductor L1-1 The input end of the second diode D2 is connected, the anode is connected to the negative end of the second charging capacitor C2; the anode of the second diode D2 is connected to the output end of the second filter inductor L1-2, and the cathode is connected to the positive end of the first charging capacitor C1, As shown in Figures 8 and 9. Therefore, during the positive half cycle of sine wave generation, when the third switch tube S3 and the fourth switch tube S4 are turned off at the same time, the energy on the second filter inductor L1-2 is transferred to the first charge through the second diode D2 Capacitor C1; during the negative half cycle of sine wave generation, when the first switch tube S1 and the second switch tube S2 are turned off at the same time, the energy on the first filter inductor L1-1 is transferred to the first filter inductor L1-1 through the first diode D1 Two charging capacitor C2.

The discharge branch can also be composed of a switch tube, and an appropriate PWM wave is applied to the control pole of the switch tube to control the first discharge branch to be turned on when the first switch tube S1 and the second switch tube S2 are both turned off. The second discharge branch is turned on when both the third switching tube S3 and the fourth switching tube S4 are turned off.

The second switching transistor S2 in the above-mentioned specific embodiments 1 and 2 can be a first thyristor (SCR), and the third switching transistor S3 can be a second thyristor (SCR). The connection relationship is as shown in Figure 8. The first thyristor The anode is connected to the second end of the filter capacitor C, the cathode is connected to the input end of the first filter inductor L1-1, the gate is controlled by a low-frequency signal, the positive pole of the second thyristor is connected to the output end of the second filter inductor L1-2, and the negative pole is connected to the filter The second terminal of the capacitor, the gate is controlled by the low frequency signal. The gates of the two thyristors are controlled by low-frequency signals to work complementary, and they switch once in half a cycle. The driving waveform is shown in Figure 7.

The second switching tube S2 in the above-mentioned specific embodiments 1 and 2 can also be a second IGBT and a third diode D3 connected in series, and the third switching tube S3 can also be a third IGBT and a fourth diode D3 connected in series. The connection relation of diode D4 is shown in FIG. 9 . The gate of the second IGBT is used to receive the PWM wave, the source is connected to the second terminal of the filter capacitor C, the drain is connected to the anode of the third diode D3, and the cathode of the third diode D3 is connected to the first filter capacitor C The input terminal of the inductor L1-1 is connected; the gate of the third IGBT is used to receive the PWM wave, the source is connected to the cathode of the fourth diode D4, the drain is connected to the second terminal of the filter capacitor C, and the fourth The anode of the diode D4 is connected to the output terminal of the second filter inductor L1-2. The gates of the two IGBTs are controlled by low frequency to switch once in half a cycle.

Specific Embodiment Three. As shown in FIG. 10 , a three-phase inverter can be formed by using three same circuits of the present invention.

Claims (10)

1. an inverter circuit comprises first charging capacitor (C1), second charging capacitor (C2), first switching tube (S1), the 4th switching tube (S4) and filter capacitor (C), described first charging capacitor (C1) and second charging capacitor (C2) series connection; It is characterized in that: also comprise the second switch pipe (S2) of first filter inductance (L1-1), second filter inductance (L1-2), unidirectional conducting and the 3rd switching tube (S3) of unidirectional conducting; Described first switching tube (S1) is connected between the input of first charging capacitor (C1) anode and first filter inductance (L1-1); The output of described first filter inductance (L1-1) is connected with first end of filter capacitor (C); Second end of described filter capacitor (C) links to each other with the series connection central point of described first charging capacitor (C1) with second charging capacitor (C2); Described the 4th switching tube (S4) is connected between the output of second charging capacitor (C2) negative terminal and second filter inductance (L1-2); The input of described second filter inductance (L1-2) is connected with first end of filter capacitor (C); Described second switch pipe (S2) is connected between first filter inductance (L1-1) input and filter capacitor (C) second end, and described the 3rd switching tube (S3) is connected between second filter inductance (L1-2) output and filter capacitor (C) second end.

2. inverter circuit as claimed in claim 1 is characterized in that: described first switching tube (S1) and the 4th switching tube (S4) are IGBT.

3. inverter circuit as claimed in claim 1 is characterized in that: described second switch pipe (S2) is first thyristor, and the anode of described first thyristor links to each other with filter capacitor (C) second end, and negative electrode links to each other with first filter inductance (L1-1) input; Described the 3rd switching tube (S3) is second thyristor, and the anode of described second thyristor links to each other with second filter inductance (L1-2) output, and negative electrode links to each other with filter capacitor (C) second end.

4. inverter circuit as claimed in claim 1, it is characterized in that: two IGBT and three diode of described second switch pipe (S2) for being in series, the source electrode of described the 2nd IGBT links to each other with filter capacitor (C) second end, drain electrode links to each other with the anode of the 3rd diode, and the negative electrode of the 3rd diode links to each other with first filter inductance (L1-1) input; Three IGBT and four diode of described the 3rd switching tube (S3) for being in series, the source electrode of described the 3rd IGBT links to each other with the negative electrode of the 4th diode, drain electrode links to each other with filter capacitor (C) second end, and the anode of described the 4th diode links to each other with second filter inductance (L1-2) output.

5. inverter circuit as claimed in claim 1 is characterized in that: described first filter inductance (L1-1) is identical with the characteristic of second filter inductance (L1-2).

6. as each described inverter circuit in the claim 1 to 5, it is characterized in that: also comprise being used to discharge release branch road and be used to discharge second of second filter inductance (L1-2) the energy storage branch road of releasing of first of first filter inductance (L1-1) energy storage, described first branch road of releasing is connected between the negative terminal of the input of first filter inductance (L1-1) and second charging capacitor (C2), and described second branch road of releasing is connected between the anode of the output of second filter inductance (L1-2) and first charging capacitor (C1).

7. inverter circuit as claimed in claim 6, it is characterized in that: described first branch road of releasing comprises first diode (D1), the negative electrode of described first diode (D1) links to each other with the input of first filter inductance (L1-1), and anode links to each other with the negative terminal of second charging capacitor (C2); Described second branch road of releasing comprises second diode (D2), and the anode of described second diode (D2) links to each other with the output of second filter inductance (L1-2), and negative electrode links to each other with the anode of first charging capacitor (C1).

8. the inverse method of an inverter circuit, described inverter circuit comprises the second switch pipe (S2) of first charging capacitor (C1), second charging capacitor (C2), first switching tube (S1), the 4th switching tube (S4), first filter inductance (L1-1), second filter inductance (L1-2), filter capacitor (C), unidirectional conducting and the 3rd switching tube (S3) of unidirectional conducting; Described first charging capacitor (C1) and second charging capacitor (C2) series connection; Described first switching tube (S1) is connected between the input of first charging capacitor (C1) anode and first filter inductance (L1-1); The output of described first filter inductance (L1-1) is connected with first end of filter capacitor (C); Second end of described filter capacitor (C) links to each other with the series connection central point of described first charging capacitor (C1) with second charging capacitor (C2); Described the 4th switching tube (S4) is connected between the output of second charging capacitor (C2) negative terminal and second filter inductance (L1-2); The input of described second filter inductance (L1-2) is connected with first end of filter capacitor (C); Described second switch pipe (S2) is connected between first filter inductance (L1-1) input and filter capacitor (C) second end, and described the 3rd switching tube (S3) is connected between second filter inductance (L1-2) output and filter capacitor (C) second end; It is characterized in that: during producing sine wave, the complementary work of first switching tube (S1) and the 4th switching tube (S4); Producing between sinusoidal wave positive half period, second switch pipe (S2) conducting is producing between sinusoidal wave negative half-cycle the 3rd switching tube (S3) conducting; The electric current that flows through first filter inductance (L1-1) is superimposed at first end of filter capacitor (C) with the electric current that flows through second filter inductance (L1-2).

9. as the inverse method of a kind of inverter circuit as described in the claim 8, it is characterized in that: during producing sine wave, the complementary symmetry of described first switching tube (S1) and the 4th switching tube (S4) is worked.

10. as the inverse method of a kind of inverter circuit as described in claim 8 or 9, it is characterized in that: described inverter circuit also comprises and is used to discharge release branch road and be used to discharge second of second filter inductance (L1-2) the energy storage branch road of releasing of first of first filter inductance (L1-1) energy storage, described first branch road of releasing is connected between the negative terminal of the input of first filter inductance (L1-1) and second charging capacitor (C2), and described second branch road of releasing is connected between the anode of the output of second filter inductance (L1-2) and first charging capacitor (C1); Producing between sinusoidal wave positive half period, when the 3rd switching tube (S3) and the 4th switching tube (S4) when disconnecting simultaneously, the energy on second filter inductance (L1-2) is transferred on first charging capacitor (C1) by second branch road of releasing; Producing between sinusoidal wave negative half-cycle, when first switching tube (S1) and second switch pipe (S2) when disconnecting simultaneously, the energy on first filter inductance (L1-1) is transferred on second charging capacitor (C2) by first branch road of releasing.

Images