TWI458248B - Inverter with current doubler rectifier and control method thereof - Google Patents

Description

Inverter with double current rectifier and control method thereof

The invention relates to an inverter circuit and a method thereof, in particular to an inverter with a double current rectifier and a control method thereof, which can effectively eliminate the output chopping current and improve the circuit performance.

At present, due to the continuous innovation of electronic products, the application of Switching Power Supply (SPS) is becoming more and more extensive, such as electric welding machines, monitors, audio, communication systems and electronic instruments. In the early days, traditional linear power supplies (LPS) were used. The linear power supply has a very large volume due to the internal isolation transformer and heat sink, and its efficiency is rather low. In recent years, the successful development of a switchable power supply (SPS) that can operate at high frequencies has improved the disadvantages of large linear transformers and low efficiency.

Please refer to FIG. 1 , which is a circuit design of a common arc welding machine. As shown in the figure, the circuit is composed of a high frequency full bridge DC/AC converter 2 and a low frequency half bridge converter. Although it has improved the disadvantages of large size and low efficiency in the past, it has a high inductance value due to its inductance, which is easy to cause conduction loss, and during the current commutation period. Serious voltage surges can occur. If you want to reduce the size of the glitch, you can use a smaller inductor value, but this method will have a severe output chopping current. Therefore, how to eliminate the output chopping current, reduce the conduction loss, and improve the voltage spur generated by the current commutation period is a problem to be solved by the present invention.

In view of the above problems of the prior art, the object of the present invention is to provide an inverter with a current doubler rectifier and a control method thereof for solving the high conduction loss and current commutation period in the prior art. Produces serious problems such as output chopping current.

According to an object of the present invention, an inverter with a double current rectifier is provided, which comprises a transformer unit, a converter unit and a double current rectifier unit. The transformer unit includes a primary side and a secondary side, the primary side includes a first coupling point and a second coupling point, and the secondary side includes a third coupling point and a fourth Coupling point. The converter unit converts the direct current to the alternating current and is coupled to the first coupling point and the second coupling point. The current-doubler rectifying unit is coupled to the third coupling point and the fourth coupling point, and includes a diode group and a transistor group, a first inductor and a second inductor, and the current-flow rectification The unit is charged by the first inductor and the second inductor, or the first inductor is discharged and the second inductor is charged to eliminate the output chopping current.

The diode set includes a first diode, a second diode, a third diode, and a fourth diode; and the transistor group includes a first transistor and a first Two transistors.

The anode of the first diode is coupled to the third coupling point, the cathode of the second diode, and one end of the first inductor. The cathode of the first diode is coupled to the third a cathode of the diode and a collector of the first transistor. The anode of the third diode is coupled to the fourth coupling point, the cathode of the fourth diode, and one end of the second inductor. The emitter of the first transistor is coupled to an output load and a collector of the second transistor. The other end of the first inductor is coupled to the other end of the second inductor and the output load. The emitter of the second transistor is coupled to the anode of the second diode and the fourth diode.

The current doubler rectifying unit controls the output current to be in a first direction by turning on the first transistor.

Wherein, the current doubler rectifying unit controls the output current to be the second direction by turning on the second transistor.

The current doubler rectifying unit controls the first and second inductors to release stored energy by simultaneously turning on the first transistor and the second transistor.

According to the object of the present invention, a control method for an inverter is further provided, which is suitable for a converter with a double current rectifier, the converter with a double current rectifier having a transformer unit, a converter unit and a double current a rectifying unit, the double current rectifying unit includes a first inductor and a second inductor, and the method for controlling the converter includes the following steps: controlling the cutoff and conduction of the internal transistor by the converter unit, and inputting a DC Converting the voltage into an input AC voltage; converting the input AC voltage into an input conversion voltage by the voltage conversion unit to the current doubler rectifying unit; discharging the first inductor and the second inductor, or discharging the first inductor The second inductor is charged to eliminate the output chopping current.

The current doubler rectifying unit further includes a first diode, a second diode, a third diode, a fourth diode, a first transistor and a second transistor.

The anode of the first diode is coupled to the third coupling point and the second diode a cathode and one end of the first inductor. The cathode of the first diode is coupled to the cathode of the third diode and the collector of the first transistor. The anode of the third diode is coupled to the fourth coupling point, the cathode of the fourth diode, and one end of the second inductor. The emitter of the first transistor is coupled to an output load and a collector of the second transistor. The other end of the first inductor is coupled to the other end of the second inductor and the output load. The emitter of the second transistor is coupled to the anode of the second diode and the fourth diode.

Wherein, the control method of the inverter of the present invention further comprises the step of controlling the output current to be in the first direction by turning on the first transistor.

Wherein, the control method of the inverter of the present invention further comprises the step of controlling the output current to be the second direction by turning on the second transistor.

The control method of the inverter of the present invention further includes the following steps: controlling the first inductor and the second inductor to release stored energy by simultaneously turning on the first transistor and the second transistor.

In view of the above, an inverter with a current doubler rectifier and a control method thereof according to the present invention may have one or more of the following advantages:

(1) The inverter with the current doubler rectifier and the control method thereof can reduce the conduction loss by the characteristic that the current flowing through each inductor is one-half of the output current.

(2) The inverter with the double current rectifier and its control method can improve the voltage surge generated by the current commutation period by using the inductance of the lower inductance value.

(3) The inverter with the double current rectifier and the control method thereof can eliminate the output by the first inductor charging and the second inductor discharging, or the first inductor discharging and the second inductor charging Chopper current.

1‧‧‧Transformer unit

2‧‧‧Commutation unit

3‧‧‧ double current rectifier unit

10‧‧‧Inverter with current doubler rectifier

11~14‧‧‧First coupling point~4th coupling point

111‧‧‧First direction

112‧‧‧second direction

V _i ‧‧‧ input voltage

Q‧‧‧Optocrystal

Q ₁ ~Q ₆ ‧‧‧First transistor ~ sixth transistor

D‧‧‧ diode

D ₁ ~D ₄ ‧‧‧First Dipole to Fourth Dipole

n _p ‧‧‧One-side coil turns

n _s ‧‧‧secondary coil turns

L ₁ ‧‧‧first inductance

L ₂ ‧‧‧second inductance

V _L1 ‧‧‧first inductor voltage

V _L2 ‧‧‧second inductor voltage

i _L1 ‧‧‧first inductor current

i _L2 ‧‧‧second inductor current

R _o ‧‧‧output load

i _o ‧‧‧Output current

Ch ₁ ~Ch ₅ ‧‧‧ Current or voltage waveform

S11~S16‧‧‧Step process

1 is a circuit diagram of a conventional arc welding machine driving converter; FIG. 2 is a circuit diagram of an embodiment of an inverter with a current doubler according to the present invention; A key waveform diagram of one embodiment of an inverter with a current doubler rectifier; FIG. 4 is a current distribution diagram of an embodiment of an inverter with a current doubler rectifier in a first state region; FIG. Is a current distribution diagram of the second and fourth state regions of one embodiment of the inverter with a current doubler of the present invention; and FIG. 6 is an embodiment of the inverter with the current double rectifier of the present invention. a current distribution diagram in a third state region; FIG. 7 is a current distribution diagram of an embodiment of an inverter having a current doubler rectifier in a fifth state region; FIG. 8 is a multiple of the present invention An embodiment of an inverter of a current rectifier and a current waveform diagram of a conventional arc welding machine for driving an inverter; FIG. 9 is an embodiment of the inverter of the present invention with a current doubler rectifier and a conventional The arc welding machine of the art drives the inverter to a voltage burst near the current commutation period. Waveform diagram; FIG. 10 is a current waveform diagram of each inductor current and output current in an embodiment of an inverter with a current doubler rectifier in the near current commutation period; and FIG. 11 is the present invention Flow chart of the control method of the converter.

Please refer to FIG. 2, which is a circuit diagram of an embodiment of an inverter with a current doubler rectifier of the present invention. As shown in the figure, the inverter 10 with a current doubler rectifier of the present invention comprises a transformer unit 1, a converter unit 2 and a double current rectifier unit 3. The transformer unit 1 includes a primary side and a secondary side, wherein the primary side has a coil number n _p and the secondary side has a coil number n _s . The primary side includes a first coupling point 11 and a second coupling point 12, and the secondary side includes a third coupling point 13 and a fourth coupling point 14.

The converter unit 2 is a full-bridge DC/AC inverter (Full-Bridge DC/AC Inverter), and the full-bridge DC/AC commutation of the inverter driven by the arc welding machine of the prior art in FIG. The device 2 is identical and includes a third transistor Q ₃ , a fourth transistor Q ₄ , a fifth transistor Q ₅ , a sixth transistor Q6 , and a voltage source V _i . The emitter of the third transistor Q ₃ is coupled to the collectors of the first coupling point 11 and the fourth transistor Q ₄ . The emitter of the fifth transistor Q ₅ is coupled to the collectors of the second coupling point 12 and the sixth transistor Q ₆ . The anode of the voltage source V _i is coupled to the collectors of the third transistor Q ₃ and the fifth transistor Q ₅ . The anode of the voltage source V _i is coupled to the emitters of the fourth transistor Q ₄ and the sixth transistor Q ₆ . The transistors Q ₃ ~ Q ₆ can be controlled using a Push-Pull Mode.

The double current rectifying unit 3 includes a first transistor Q ₁ , a second transistor Q ₂ , a first diode D ₁ , a second diode D ₂ , a third diode D ₃ , and a fourth diode D _{4. The} first inductor L ₁ , the second inductor L _{2 ,} and the output load R _o . It should be noted that all the first inductor voltage V _L1 , the voltage polarity of the second inductor voltage V _L2 , and the current directions of the first inductor current i _L1 and the second inductor current i _L2 are all charged during the inductor charging. Voltage direction and current direction. In this embodiment, the first inductor L1 and the second inductor L2 may be arranged in an interlaced manner, but are not limited thereto. When the converter unit 2 inputs a voltage to the double current rectifying unit 3 via the transformer unit 1, the first inductor L ₁ and the second inductor L ₂ are respectively applied with a forward bias and a reverse bias, resulting in a charge-discharge. The effects, detailed process will be discussed in subsequent implementations. The anode of the first diode D ₁ is coupled to the third coupling point 13 , the cathode of the second diode D ₂ , and one end of the first inductor L ₁ . The cathode of the first diode D ₁ is coupled to the cathode. a cathode of the third diode D ₃ and a collector of the first transistor Q ₁ ; an anode of the third diode D ₃ is coupled to the fourth coupling point 14 and the fourth electrical diode D ₄ One end of the negative electrode and the second inductor L ₂ ; the emitter of the first transistor Q ₁ is coupled to the collector of the output load _Ro and the second transistor Q ₂ ; the other end of the first inductor L ₁ is coupled to the second The other end of the inductor L ₂ and the output load R _o ; and the emitter of the second transistor Q _{2 are} coupled to the anodes of the second and fourth diodes Q ₂ and D ₄ . Wherein, the above-mentioned transistors can be Bipolar Junction Transistors (BJT), and the first transistor Q ₁ and the second transistor Q ₂ can be turned on or off by using a microprocessor (Microprocessor). )control.

Please refer to FIG. 3 and FIG. 4 together, which are key waveform diagrams of an embodiment of the inverter with a current doubler rectifier of the present invention and a current distribution diagram thereof in the first state region. As shown, when the inverter 10 of the current doubler rectifier of the present invention operates in the first state region (t ₀ ~ t ₁ ), the transistors Q ₁ , Q ₃ and Q _{6 are} turned on, and the voltage source V _{i is} passed via The transistors Q ₃ and Q ₆ transfer energy to the secondary side of the transformer unit 1. Since the third coupling point 13 is at a high potential, the first diode D _{1 is} turned on, and an output current i _o whose current direction is the first direction 111 is generated and passes through the output load R _o . At this time, the second inductor L ₂ is biased in the same direction as the charging direction (the same direction as V _L2 ), and therefore, the second inductor L _{2 is} charged and the second inductor current i _{L2 is} increased. However, the first inductor L ₁ is reverse biased in the opposite direction to its charging direction (opposite to V _L1 ), so that the first inductor L _{1 is} discharged and the first inductor current i _{L1 is} decreased. As a result, the output chopping current is effectively eliminated because one of the second inductor current i _L2 and the first inductor current i _{L1 is} increased and decreased. The current distribution diagram is shown in Fig. 4.

Please refer to FIG. 3 and FIG. 5 together. FIG. 5 is a current distribution diagram of the second and fourth state regions of an embodiment of the inverter with a current doubler rectifier of the present invention. As shown in the figure, when the inverter 10 of the current doubler rectifier of the present invention operates in the second state region (t ₁ ~ t ₂ ), or is the Imput Dead Time State Region, the electricity The crystals Q ₃ to Q ₆ are all turned off, but the first transistor Q ₁ is still turned on. The voltage source Vi stops transmitting energy via the transforming unit 1 to the output load R _o . At this time, the output of the first inductor L ₁ and the second inductor L ₂ simultaneously provides the output load R _o energy. The current distribution diagram is shown in Fig. 5.

Please refer to FIG. 3 and FIG. 6 together. FIG. 6 is a current distribution diagram of an embodiment of an inverter with a current doubler in the third state region. As shown, when the inverter 10 of the current doubler rectifier of the present invention operates in the third state region (t ₂ ~ t ₃ ), the transistors Q ₁ , Q ₄ and Q _{5 are} turned on, and the voltage source V _{i is} passed via The transistors Q ₄ and Q ₅ transfer energy to the secondary side of the transformer unit 1. Since the fourth coupling point 14 is at a high potential, the third diode D _{3 is} turned on, and an output current i _o having a current direction of the first direction 111 is generated and passed through the output load R _o . At this time, since the second inductor L ₂ is reversely biased in the opposite direction to the charging direction, the second inductor L _{2 is} discharged and the second inductor current i _{L2 is} decreased. Conversely, the first inductor current i _L1 is increased. Therefore, the output chopping current is effectively eliminated because one of the first inductor current i _L1 and the second inductor current i _{L2 is} increased and decreased. The current distribution diagram is shown in Fig. 6.

Please refer to FIG. 3 and FIG. 5 together. As shown in the figure, when the inverter 10 of the current doubler rectifier of the present invention operates in the fourth state zone (t ₃ ~ t ₄ ), it enters the input hysteresis again. In the Imput Dead Time State Region, the transistors Q ₃ ~Q ₆ are all turned off, but the first transistor Q ₁ is still turned on. Therefore, the fourth state zone is the same as the second state zone, and both the first inductor L ₁ and the second inductor L ₂ simultaneously provide the output load R _o energy. The current distribution diagram is shown in Fig. 5. Pulse Width Modulation (PWM) prevents the transistor from being turned on at the same time, causing a short circuit and forming unnecessary current surges, which in turn leads to circuit damage, thus controlling the circuit to enter a state of vacancy. The aforementioned microprocessor, push-pull mode and PWM control circuit are conventional techniques, and will not be described here.

Please refer to FIG. 3 and FIG. 7 together. FIG. 7 is a current distribution diagram of an embodiment of the inverter with a current doubler rectifier in the fifth state region. As shown in the figure, when the inverter 10 of the current doubler rectifier of the present invention operates in the fifth state region (t ₅ ~ t ₆ ), or is the output current commutation state region, at this time, the transistor Q ₃ ~ When Q ₆ is turned off at the same time, the voltage source Vi stops inputting energy to the double current rectifying unit 3. The first and second transistors Q ₁ and Q ₂ must be simultaneously turned on, so that the first and second inductors L ₁ and L ₂ release the stored energy. The current distribution diagram at this time is as shown in Fig. 7. Once the first transistor Q _{1 is} turned off, the output current i _{o is} then converted from the first direction 111 to the second direction 112. At this moment, the inverter 10 will repeatedly perform the operation from the first state region to the fourth state region. After a period of time Δt, the output current will reach a stable value (-i _o ), as shown in Fig. 3. Show. It can be clearly understood from the above steps that the commutation unit 2 (full-bridge DC/AC converter) on the primary side of the transformer unit 1 can generate an AC voltage and transmit it to the transformer unit 1 The secondary current rectifying unit 3, and the double current rectifying unit 3 can generate an adjustable positive current and a negative current by using the first inductor L ₁ and the second inductor L ₂ such that i _o =i _L1 +i _L2 Effectively eliminates the effect of output chopping current.

It should be noted that those having ordinary knowledge in the art to which the present invention pertains should understand that the active elements in the inverter 10 with the current doubler rectifier of the present invention are not limited to the bipolar junction transistors in this embodiment. It can also be a Metal-Oxide-Semiconductor Field-Effect Transistor (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET) or Insulated Gate Bipolar Transistor (IGBT). Similarly, the commutation unit 2 is not limited to the full bridge DC/AC converter 2 in this embodiment, and may be in other different circuit forms, such as a half bridge converter, etc., but due to the half bridge type. The converter output voltage is only half of the full bridge. In the case of outputting the same power, the output current of the half-bridge converter needs to be twice that of the full-bridge type, so the full-bridge converter is more suitable under the premise of high power output.

Please refer to Figure 8, Figure 9, and Figure 10, and refer to Figure 1 and Figure 2 together. Figure 8 is a current waveform diagram of an embodiment of an inverter of a current-flowing rectifier of the present invention and an arc welding machine driven converter of the prior art, and Figure 9 is a current-flowing rectifier of the present invention. An embodiment of an inverter and an arc welding machine of the prior art drive a voltage surge waveform of the inverter when approaching a current commutation period, and FIG. 10 is an inverter with a current doubler of the present invention. One embodiment is a current waveform diagram of each inductor current and output current when approaching the current commutation period. The above experimental results were operated with the following parameters, R _o = 0.06, i _L1 = i _L2 = 36 μH, L = 72 μH, N _p : N _s = 10:1 and V _i = 155V. The switching frequency of the full-bridge DC/AC converter 2 is 20 kHz, the output current is a square wave with a frequency of 100 Hz, the duty cycle is 50%, the amplitude is 100 A, and the commutation time t _c is 4 μs. As shown in Fig. 8, Ch1_i _o is the output current waveform of the inverter 10 with the current doubler of the present invention, and Ch2_i _o is the output current waveform of the arc welding machine driven converter of the prior art. It can be clearly seen from the figure that the inverter 10 of the present invention with a current doubler rectifier can achieve the same current output as the prior art. As shown in FIG. 9, the arc voltage welding machine in the conventional art arc welding machine drives the inverter voltage VL to generate a voltage surge of about 500 V, and the first inductor voltage V _{L1 of the} present invention generates only about 40 V. The voltage surges thus effectively improve the problem of high voltage surges in the prior art. As shown in Fig. 10, the first inductor current i _L1 and the second inductor current i _L2 have severe chopping phenomenon, but since the output current i _o =i _L1 +i _L2 , the chopping of the output current can be eliminated. phenomenon.

According to the above experimental results, the inverter 10 of the present invention with the current doubler rectifier can effectively improve the problem of voltage surge in the prior art. Further, under the same output current condition and the transient response of the same specific case, although the inverter 10 of the current doubler rectifier of the present invention uses a lower inductance value, the first inductor current i _L1 And the interleaved operation of the second inductor current i _L2 enables the output current i _{o to} still reach a high current value equivalent to the prior art. Please refer to Table 1, which is a comparison table of conversion efficiency of an embodiment of an inverter of a current-flowing rectifier of the present invention and an arc welding machine driven converter of the prior art. It can be clearly seen from Table 1 that the inverter 10 with the current doubler rectifier of the present invention is superior to the prior art in terms of conversion efficiency, especially at high output currents io.

Please refer to FIG. 11 , which is a flow chart of the control method of the inverter of the present invention. As shown in the figure, the control method of the inverter of the present invention is applicable to an inverter with a double current rectifier. The inverter with the double current rectifier has a transformer unit, a commutation unit and a double current rectification unit. The current doubler rectifying unit includes a first inductor, a second inductor, a first diode, a second diode, a third diode, a fourth diode, a first transistor, and a second transistor. The control method of the converter comprises the following steps: (S11) controlling the cut-off and conduction of the internal transistor by the converter unit, converting the input DC voltage into an input AC voltage; (S12) converting the input AC voltage by the transformer unit Inputting the converted voltage to the double current rectifying unit; (S13) controlling the output current to be the first direction by turning on the first transistor; (S14) controlling the output current to be the second direction by turning on the second transistor; (S15) Controlling the first inductor and the second inductor to release stored energy by simultaneously turning on the first transistor and the second transistor; and (S16) charging by the first inductor and the second inductor, or the first inductor discharge and the second inductor Charge to eliminate the output chopping current.

The detailed description and embodiments of the control method of the inverter of the present invention have been described above for the inverter of the present invention with a current doubler rectifier, and will not be described here for the sake of brevity.

In summary, the inverter of the present invention has a method of replacing the output rectifier of the conventional art circuit with a current doubler, which can achieve low conduction loss and effectively eliminate the output chopping current. Moreover, the use of inductors with lower inductance values can more effectively solve the problem of high voltage surges generated in the current commutation period in the prior art.

The above is intended to be illustrative only and not limiting. Anything that does not deviate from the invention God and the scope, and equivalent modifications or changes to them, shall be included in the scope of the patent application attached.

1‧‧‧Transformer unit

2‧‧‧Commutation unit

3‧‧‧ double current rectifier unit

10‧‧‧Inverter with current doubler rectifier

11~14‧‧‧First coupling point~4th coupling point

111‧‧‧First direction

112‧‧‧second direction

V _i ‧‧‧ input voltage

Q ₁ ~Q ₆ ‧‧‧First transistor ~ sixth transistor

D ₁ ~D ₄ ‧‧‧First Dipole to Fourth Dipole

n _p ‧‧‧One-side coil turns

n _s ‧‧‧secondary coil turns

L ₁ ‧‧‧first inductance

L ₂ ‧‧‧second inductance

V _L1 ‧‧‧first inductor voltage

V _L2 ‧‧‧second inductor voltage

R _o ‧‧‧output load

i _o ‧‧‧Output current

Claims (12)

An inverter with a double current rectifier, comprising: a transformer unit comprising a primary side and a secondary side, the primary side comprising a first coupling point and a second coupling point, and the second coupling point The secondary side includes a third coupling point and a fourth coupling point; a converter unit converts the direct current to the alternating current and is coupled to the first coupling point and the second coupling point; and doubles The current rectifying unit is coupled to the third coupling point and the fourth coupling point, and includes a diode group and a transistor group, a first inductor and a second inductor, and the current doubler rectifier unit The first inductor is charged and the second inductor is discharged, or the first inductor is discharged and the second inductor is charged to eliminate the output chopping current. The inverter of claim 2, wherein the diode group comprises a first diode, a second diode, a third diode, and a fourth a diode, and the transistor group includes a first transistor and a second transistor. An inverter having a current doubler rectifier according to the second aspect of the invention, wherein an anode of the first diode is coupled to the third coupling point, a cathode of the second diode, and the first One end of the inductor; the cathode of the first diode is coupled to the cathode of the third diode and the collector of the first transistor; the anode of the third diode is coupled to the fourth coupling point a cathode of the fourth diode and one end of the second inductor; an emitter of the first transistor is coupled to an output load and a collector of the second transistor; and the other end of the first inductor is coupled The other end of the second inductor and the output load; and the emitter of the second transistor is coupled to the anode of the second diode and the fourth diode. An inverter with a current doubler rectifier according to claim 3, wherein the current doubler rectifying unit controls the output current to be in a first direction by turning on the first transistor. An inverter with a current doubler rectifier according to claim 3, wherein the current doubler rectifying unit controls the output current to be in a second direction by turning on the second transistor. The inverter having a current doubler rectifier according to claim 3, wherein the current doubler rectifying unit controls the first inductor and the second by simultaneously turning on the first transistor and the second transistor The inductor releases the stored energy. The invention relates to a converter control method, which is suitable for a converter of a double current rectifier, wherein the converter with a double current rectifier has a transformer unit, a converter unit and a double current rectifier unit, the double current rectifier unit The method includes the following steps: controlling the cut-off and conduction of the internal transistor by the converter unit to convert an input DC voltage into an input AC voltage; Converting the input AC voltage into an input conversion voltage to the current-doubler rectifying unit; and discharging the first inductor and the second inductor, or charging the first inductor and charging the second inductor Eliminate the output chopping current. The control method of the inverter of claim 7, wherein the current doubler rectifying unit further comprises a first diode, a second diode, a third diode, and a fourth a pole body, a first transistor and a second transistor. The control method of the inverter of claim 8, wherein the anode of the first diode is coupled to the third coupling point, the cathode of the second diode, and the first inductor The cathode of the first diode is coupled to the cathode of the third diode and the collector of the first transistor; the anode of the third diode is coupled to the fourth coupling point, a cathode of the fourth diode and one end of the second inductor; an emitter of the first transistor The other end of the first inductor is coupled to the other end of the second inductor and the output load; and the emitter of the second transistor is coupled to the emitter The second diode and the anode of the fourth diode. The control method of the inverter of claim 9, further comprising the step of controlling the output current to be the first direction by turning on the first transistor. The control method of the inverter of claim 9, further comprising the step of: controlling the output current to be the second direction by turning on the second transistor. The control method of the inverter of claim 9, further comprising the step of: controlling the first inductor and the second inductor to be released by simultaneously turning on the first transistor and the second transistor The energy stored.