TW202412445A - Two-way converter - Google Patents

Abstract

The present invention relates to a two-way converter, which is composed of an isolated step-down converter and a non-isolated step-down converter, and can be output and input from the first input/output and the second output/input respectively, which can not only reduce the number of components used in the converter, but also reduce the development cost of the converter, and increase the practical efficiency in its overall implementation.

Description

Bidirectional converter

The present invention relates to a bidirectional converter, and more particularly to a converter that can not only reduce the number of components used in the converter, but also reduce the development cost of the converter, while increasing the practical performance characteristics in its overall implementation and use.

With the rapid development of modern science and technology and economy, various convenient and practical electronic products are continuously introduced and widely used in people's daily life. Since the industrial revolution, a large number of heavy industry and petrochemical industry technologies have developed rapidly. In the process of production and development, a large amount of petroleum and natural gas and other petrochemical energy sources that pollute the environment are used. The large-scale burning of petrochemical energy will produce carbon dioxide that pollutes the air, which will cause holes in the ozone layer in the atmosphere, and will indirectly cause serious air pollution and global warming. Therefore, in 1997, in order to solve the exhaust pollution caused by heavy industry, countries passed the Kyoto Protocol in Tokyo, Japan, stipulating that all industrial powers must reduce greenhouse gas emissions. Environmental awareness and legal regulations are gradually gaining attention. When developing electronic technology, we must also pay attention to environmental issues, because low conversion efficiency of electronic products will also cause energy waste. Therefore, researching how to effectively improve the conversion efficiency of circuits has become the focus of current technological development. Therefore, in the field of power electronics, effectively improving the conversion efficiency of circuits is an important research goal.

At present, DC-to-DC converters are the most widely used and the most diverse type of converters. They are often used in battery energy storage systems, DC power supplies, various electronic products, etc. The characteristic of this converter is that both the input power supply and the load end are DC, and the current flows from the input end to the output end, so all the components in the circuit are unidirectional. In DC circuits, the duty cycle of the transistor switch trigger signal is generally changed to control the rise or fall of the output voltage. In general DC-to-DC converters, the input and output ends are electrically connected. If the input end is grounded, the grounding of the output end will be the same as the input end. The way to electrically isolate the two ends is to use a transformer, and the use of electrical isolation is to prevent the current in the circuit from being directly connected. The current flows directly into the other side, which can reduce the mutual interference between the two different circuits. Although the current cannot flow directly through the transformer using electrical isolation, the energy can be transferred in other ways. The transformer uses electromagnetic induction to pass the two coils through the iron core. The current flowing through one side will generate a magnetic field, and the principle of electromagnetic mutual induction will generate a potential difference in the coil on the other side, which will cause the closed circuit on the other side to generate current and then move.

This type of converter uses power electronic circuits to convert fixed DC input voltage into adjustable DC output of different levels. Therefore, for DC/DC converters that need to operate in a wide output range, bidirectional buck-boost converters provide the best choice. Bidirectional buck-boost converters allow the purpose of power conversion to be achieved through bidirectional power transmission using the same circuit components. Bidirectional buck-boost converters can not only reduce the number of components used in the converter, but also reduce the development cost of the converter.

Therefore, the inventor, in view of this, has adhered to the rich design development and actual manufacturing experience in the relevant industry for many years, and has further studied and improved the existing structure and defects to provide a bidirectional converter in order to achieve the purpose of better practical value.

The main purpose of the present invention is to provide a bidirectional converter, which is mainly composed of an isolated buck-boost converter and a non-isolated buck-boost converter, and can perform output and input through a first input/output terminal and a second output/input terminal, respectively. This can not only reduce the number of components used in the converter, but also reduce the development cost of the converter, and increase the practical performance characteristics in its overall implementation and use.

In order to make the technical content, purpose of the invention and the effects achieved by the present invention more complete and clear, they are described in detail below, and please refer to the disclosed drawings and figure numbers:

First, please refer to the first figure of the first use state circuit diagram of the present invention and the second figure of the second use state circuit diagram of the present invention. As shown in the figure, the converter (1) of the present invention is provided with a first input/output terminal (11) connected in parallel, an isolated buck-boost converter (12), a first capacitor , a non-isolated buck-boost converter (13) and a second input/output terminal (14); wherein:

The first input/output terminal (11) is connected to the capacitor of the isolated buck-boost converter (12). connected in parallel to the capacitor of the isolated buck-boost converter (12) The first end is connected to the primary side of the transformer The first end of the transformer primary side Forming a primary magnetizing inductance , on the primary side of the transformer The second end is connected to a first switch The first end of the capacitor The second end is connected to the first switch The second end is connected to the primary side of the transformer. With transformer secondary side , the secondary side of the transformer Forming a secondary magnetizing inductance , the secondary side of the transformer The first end of the The first end of the transformer is on the secondary side. The second end is connected to a second switch The first end of the second switch The second end of the first capacitor The non-isolated buck-boost converter (13) is connected to the second end of the first capacitor. The first end is connected to a third switch The first end of the third switch The second end of each of the switches is connected to a fourth switch. The first terminal and the inductor The first end of the inductor The second end of each of the switches is connected to a fifth switch. The first end and the sixth switch The first end of the sixth switch The second end is connected to the second capacitor The first end of the fourth switch The second end of the fifth switch The second end and the second capacitor The second end of each capacitor is connected to the first capacitor The second ends of the second capacitor are connected to each other, and then the second capacitor The second input/output terminal (14) is connected in parallel.

The circuit operation principle of the converter (1) is briefly analyzed. When the first input/output terminal (11) performs input and the second input/output terminal (14) performs output, the converter (1) is operated in an isolated mode. Assume that:

1. The circuit operates in steady state. All voltages and currents are periodic signals that start and end at the same position during the switching cycle.

2. Both transistor switches and diodes are ideal components. The switch has zero lag time when switching, no leakage current when turned on, and no forward/reverse voltage drop when turned off.

3. The output filter capacitor is ideal with no loss and large capacity, so that the output voltage is maintained at a fixed value.

4. Ignore the internal parasitic resistance of the inductor and capacitor and the transformer coil resistance and leakage inductance.

155V is inputted from the first input/output terminal (11), and the duty cycle D is adjusted to 0.2-0.7. When the duty cycle is 0.2, the operation is in the DCM [Discontinuous Conduction Mode] mode, and when the duty cycle is adjusted to 0.7, the operation is in the CCM [Continuous Conduction Mode] mode.

When the duty cycle is 0.2, the operation of the converter (1) in a switching cycle can be divided into three stages according to whether each switch is switched on or off. For the timing and waveform, please refer to the first timing diagram of the present invention in the third figure:

Working mode 1 ]:[First switch ：ON, second switch ：OFF、Third switch ：ON, the fourth switch ：OFF, fifth switch ：ON, the sixth switch ：OFF］：Please refer to the fourth figure of the first stage equivalent linear circuit diagram of the present invention [isolation type], in working mode 1, the first switch to ON, turn the second switch Operation is that the flywheel diode is OFF, so that when the first switch When conducting, the primary side of the transformer The voltage across the upper two terminals will be equal to the input voltage, so

, (1)

At this time, the current will flow into the primary magnetizing inductance of the transformer. Energy is stored in the primary side. Since the polarity of the primary side is opposite to that of the secondary side, the voltage on the secondary side is for

, (2)

At this time, the second switch The voltage across the flywheel diode is

, (3)

Make the second switch The flywheel diode is reverse biased and open-circuited, and the first capacitor Providing a load to the second input/output terminal (14) The energy required to be consumed. When conducting, the primary magnetizing inductance of the transformer Continuous energy storage, so the primary current It increases linearly when When the first switch It will switch to OFF to proceed to the next stage.

Working mode 2 ]:[First switch ：OFF, Second switch ：ON, third switch ：OFF, 4th switch ：ON, fifth switch ：OFF, 6th switch ：ON］：Please refer to the fifth figure of the second stage equivalent linear circuit diagram of the present invention [isolation type], in working mode 2, the first switch to OFF, turn the second switch , the fourth switch , the sixth switch The operation is to turn the flywheel diode ON. , the first switch Switch to OFF, so that the primary current of the transformer The magnetic flux of the core decreases, and the current flows out from the primary side, while the current flows into the secondary side, making the flywheel diode current positive and conducting. At this time, the secondary voltage is

, (4)

The secondary voltage is converted back to the primary side, and we get

(5)

Working mode three ]:[First switch ：OFF, Second switch ：OFF、Third switch ：OFF, 4th switch ：ON, fifth switch ：OFF, 6th switch ：ON］：Please refer to the sixth figure of the third stage equivalent linear circuit diagram of the present invention [isolation type], in working mode three, the first switch to OFF, turn the second switch The operation is that the flywheel diode is OFF, at this time the switch remains in the off state, and the primary magnetizing inductance of the transformer The energy has been fully released, that is Also , so the second switch The flywheel diode is also turned off. Providing a load to the second input/output terminal (14) The energy required to consume.

When the duty cycle is 0.7, the operation of the converter (1) in one switching cycle can be divided into two stages according to whether each switch is switched on or off. For the timing and waveform, please refer to the second timing diagram of the present invention in Figure 7. These two stages are respectively the same as the working mode 1 and the working mode 2 when the duty cycle is 0.2. The only difference is that the operation is in CCM [Continuous Conduction Mode] mode, which will not be described in detail here.

When the second input/output terminal (14) performs input and the first input/output terminal (11) performs output, so that the converter (1) operates in a non-isolated mode; assuming that:

1. The circuit operates in a steady state.

2. All components in the circuit are in ideal condition and the switch has zero lag time when switching.

3. Assuming the output voltage is fixed, the capacitor needs to be quite large.

4. The inductor current is CCM (continuous conduction mode).

5. The switching cycle is , the switch conduction time is , the switch cut-off time is .

48V is input from the second input/output terminal (14), and the duty cycle D is adjusted to 0.2-0.7, and both operate in CCM [Continuous Conduction Mode].

When the working cycle is 0.2, the operation of the converter (1) in one switching cycle can be divided into two stages according to whether each switch is switched on or off. For the timing and waveform, please refer to the third timing diagram of the present invention in Figure 8:

Working mode 1 ]:[First switch ：OFF, Second switch ：ON, third switch ：OFF, 4th switch ：ON, fifth switch ：OFF, 6th switch ：ON］：Please refer to the ninth figure of the first stage equivalent linear circuit diagram of the present invention [non-isolated type], in working mode 1, the fourth switch and the sixth switch To the on state, turn the third switch and the fifth switch Operation is that the flywheel diode is in the cut-off state due to reverse bias, at which time the inductor Inductor voltage is positive, and the current flows into the inductor To store energy, the inductor current presents a linear rise, at which time the energy required by the first input/output terminal (11) is supplied by the first capacitor Provided. The voltage-current relationship equation for this operation mode is:

(6)

The inductor current Change in rise for

(7)

Working mode 2 ]:[First switch ：ON, second switch ：OFF、Third switch ：ON, the fourth switch ：OFF, fifth switch ：ON, the sixth switch ：OFF］：Please refer to the second stage equivalent linear circuit diagram of the present invention in Figure 10 [non-isolated type], in working mode 2, the fourth switch and the sixth switch is in the cut-off state, at which time the third switch and the fifth switch The operation is that the flywheel diode will have current flowing into it and the forward bias will be in the on state, and the inductor Because there is no continuous energy supply, the inductor begins to release the stored energy, so the inductor voltage is negative, and the inductor current presents a linear decrease, at which time the energy required by the first input/output terminal (11) is determined by the inductor current Provided. The voltage-current relationship equation for this operation mode is:

(8)

The inductor current Change in descent for

(9)

When the duty cycle is 0.7, the operation of the converter (1) in one switching cycle can also be divided into two stages according to whether each switch is turned on or off. For the timing and waveform, please refer to the fourth timing diagram of the present invention in Figure 11. These two stages are respectively the same as the working mode 1 and the working mode 2 when the duty cycle is 0.2, and will not be described in detail here.

The converter (1) is operated at a switching frequency of 100 kHz, and the isolated buck-boost converter (12) and the non-isolated buck-boost converter (13) are tested respectively; the isolated buck-boost converter (12) has the following modes: discontinuous current mode [DCM], duty cycle operation D at 0.2, input from the first input/output terminal (11) , outputted by the second input/output terminal (14) , and continuous current mode [CCM], duty cycle D is operated at 0.7, and the first input/output terminal (11) is input , outputted by the second input/output terminal (14) .

The transformer turns ratio of the isolated buck-boost converter (12) The winding ratio is designed to be 3:1. Due to the influence of the transformer winding frame, the primary side magnetizing inductance is measured after winding. for , and the secondary magnetizing inductance for .

The primary side magnetizing inductance If you need to operate in continuous current mode, the minimum formula is

, (10)

Please refer to Table 1 below for the parameters of each component. When Duty is 0.2

, (11)

When Duty is 0.7

, (12)

From equations (11) and (12), it can be deduced that if the circuit is to operate in continuous current mode, the primary magnetizing inductance is The required minimum value, and the actual winding and measured data of the primary magnetizing inductance for Therefore, it can be inferred that when the Duty is 0.2, the circuit operates in the discontinuous current mode, and when the Duty is 0.7, the circuit operates in the continuous current mode.

The output voltage formula for duty operation at 0.7 in continuous current mode is:

, (13)

, (14)

The output voltage formula for duty operation at 0.2 in discontinuous current mode is:

, (15)

, (16)

Table 1 Component parameters of isolated buck-boost converter Switching frequency Working cycle Input voltage Primary magnetizing inductance Capacitance First capacitor First switch Second switch Load Primary side leakage

When inputted from the first input/output terminal (11), since the duty cycle D operates at 0.2 to 0.7, the actions are roughly similar and are both in the buck mode. When the duty cycle D operates at 0.2, the first input/output terminal (11) inputs The second input/output terminal (14) outputs , the actual output voltage is , at this time the circuit is in discontinuous conduction mode.

Please also refer to the twelfth figure of the invention The driving signal waveform and , Cross-voltage on switch , The actual waveform diagram [isolation type D=0.2] shows that when the drive signal is sent to the switch, it can be observed that it is on or off in the same working mode. Please also refer to Figure 13 for the switch of this invention. and Signal and current As shown in the actual waveform diagram [isolation type D=0.2], when the first switch When the switch is on, the input current flows through the primary magnetizing inductance. Energy storage starts. When the voltage on the switch is equal to the input voltage, no current flows and the inductor energy storage stops. The next working stage is switched to the second switch. When the inductor is turned on, the inductor will start to discharge. Since this circuit operates in DCM mode, the inductor current will drop to zero and the switches will be in the off state. Please refer to Figure 14 for the voltage and current waveforms of the primary and secondary sides of the transformer of the present invention [isolation type D=0.2]. When the inductor voltage is positive, the inductor current will rise linearly and store energy, and when the inductor voltage is negative, the inductor current will drop linearly and gradually release energy. The actual input voltage is 153.4V, the input current is 0.06A, the input power is 9.3W, the output voltage is 34V, the output current is 0.27A, the output power is 9.18W, and the efficiency is 98.71%.

When the duty cycle D is operated at 0.7, the first input/output terminal (11) inputs The second input/output terminal (14) outputs , while the actual output voltage is , at which point the circuit is in continuous conduction mode.

Please also refer to the 15th illustration of the invention The driving signal waveform and , Cross-voltage on switch , As shown in the actual waveform diagram [isolation type D=0.7], it can be observed that when the drive signal is sent to the switch, it is either on or off in the same working mode. Please also refer to Figure 16 for the switch of the present invention. and Signal and current As shown in the actual waveform diagram [isolation type D=0.7], when the first switch When the switch is on, the input current flows through the primary magnetizing inductance. Energy storage starts. When the voltage on the switch is equal to the input voltage, no current flows and the inductor energy storage stops. The next working stage is switched to the second switch. The inductor will start to discharge when it is turned on. Please refer to the waveform of the voltage and current on both ends of the primary and secondary sides of the transformer of the present invention in Figure 17 [Isolation Type D=0.7]. When the inductor voltage is positive, the inductor current will rise linearly and store energy, and when the inductor voltage is negative, the inductor current will drop linearly and gradually release energy. The actual input voltage is 153.2V, the input current is 0.81A, the input power is 123.86W, the output voltage is 118.7V, the output current is 0.99A, the output power is 117.42W, and the efficiency is 94.8%.

In addition, the non-isolated buck-boost converter (13) has the following modes: the duty cycle D is operated at 0.2, the second input/output terminal (14) is used to input , inputted by the first input/output terminal (11) The duty cycle D is operated at 0.7, and the second input/output terminal (14) is used for input. , inputted by the first input/output terminal (11) .

Please also refer to Table 2 below:

Table 2 Non-isolated buck-boost converter component parameters Switching frequency Working cycle 0.2 0.7 Input voltage Inductor First capacitor Second capacitor Switch , Switch , Load

When the duty cycle D is operated at 0.2, the second input/output terminal (14) inputs , the first input/output terminal (11) outputs , while the actual output voltage is

Please also refer to the switch of the invention in Figure 18 , The driving signal waveform , The actual waveform diagram [non-isolated type D=0.2] shows that it mainly provides a driving signal to the switch to conduct or cut off. Please also refer to the fourth switch of the present invention in Figure 19. Signal Terminal and current Real side waveform diagram [non-isolated type D=0.2] and Figure 20 of the sixth switch of the present invention Signal Terminal and current As shown in the real side waveform [non-isolated type D=0.2], when the fourth switch , the sixth switch When the inductor is on, the input current flows through the inductor. Energy storage starts. When the voltage on the switch is equal to the input voltage, no current flows and energy storage in the inductor stops. Please also refer to Figure 21 for the inductor of the present invention. Voltage and current As shown in the actual waveform diagram [non-isolated type D=0.2], when the inductor voltage is positive, the inductor current will rise linearly and store energy, and when the inductor voltage is negative, the inductor current will drop linearly and gradually release energy. Please also refer to Figure 22 for the fifth switch of the present invention. Signal Terminal and current The actual side waveform diagram [non-isolated type D=0.2] and the third switch of the invention in Figure 23 Signal Terminal and current As shown in the actual waveform diagram [non-isolated D=0.2], when the switch voltage is negative, the current cannot flow through the parasitic diode inside the switch. When the switch voltage is zero, it will become conductive and the current will flow through the third switch. The actual input voltage is 48.24V, the input current is 0.05A, the input power is 2.48W, the output voltage is 17.26V, the output current is 0.13A, the output power is 2.32W, and the efficiency is 93.5%.

When the duty cycle D is operated at 0.7, the second input/output terminal (14) inputs , the first input/output terminal (11) outputs , while the actual output voltage is

Please also refer to the switch of the invention in Figure 24. , The driving signal waveform , The actual waveform diagram [non-isolated type D=0.7] shows that it mainly provides a driving signal to the switch to conduct or cut off. Please also refer to the fourth switch of the invention in Figure 25. Signal Terminal and current Real side waveform diagram [non-isolated type D=0.7] and Figure 26 of the sixth switch of the present invention Signal Terminal and current As shown in the real side waveform [non-isolated type D=0.7], when the fourth switch , the sixth switch When the inductor is on, the input current flows through the inductor. Energy storage starts. When the voltage on the switch is equal to the input voltage, no current flows and energy storage in the inductor stops. Please also refer to Figure 27 for the fifth switch of this invention. Signal Terminal and current Actual side waveform diagram [non-isolated type D=0.7] and Figure 28 of the third switch of the present invention Signal Terminal and current As shown in the actual waveform diagram [non-isolated D=0.7], when the switch voltage is negative, the current cannot flow through the parasitic diode inside the switch. When the switch voltage is zero, it will become conductive and the current will flow through the third switch. The actual input voltage is 48.42V, the input current is 3.65A, the input power is 176.78W, the output voltage is 133.8V, the output current is 1.13A, the output power is 150.53W, and the efficiency is 85.15%.

From the above description, it can be known from the implementation description of the present invention that, compared with the prior art, the present invention mainly makes the converter consist of an isolated buck-boost converter and a non-isolated buck-boost converter, and can perform output and input respectively through the first input/output terminal and the second output/input terminal, which can not only reduce the number of components used in the converter, but also reduce the development cost of the converter, and increase the practical performance characteristics in its overall implementation and use.

However, the aforementioned embodiments or drawings do not limit the product structure or usage of the present invention. Any appropriate changes or modifications by a person having ordinary knowledge in the relevant technical field should be deemed to be within the patent scope of the present invention.

In summary, the embodiments of the present invention can achieve the expected effects, and the specific structure disclosed therein has not been seen in similar products, nor has it been disclosed before the application. It fully complies with the provisions and requirements of the Patent Law. Therefore, an application for an invention patent is filed in accordance with the law, and we sincerely request your review and grant of the patent. We would be grateful for your kindness.

1: Converter

11: First input/output terminal

12:Isolated Buck-Boost Converter

:Capacitor

:Transformer primary side

:Primary side magnetizing inductance

:First switch

:Transformer secondary side

:Secondary magnetizing inductance

: Second switch

:First Capacitor

13: Non-isolated buck-boost converter

:The third switch

:Fourth switch

:Inductor

:Fifth switch

:Sixth switch

: Second capacitor

14: Second input/output port

Figure 1: Circuit diagram of the first use state of the present invention

Figure 2: Circuit diagram of the second use state of the present invention

Figure 3: First timing diagram of the present invention

Figure 4: Equivalent linear circuit diagram of the first stage of the present invention [isolated type]

Figure 5: Equivalent linear circuit diagram of the second stage of the present invention [isolation type]

Figure 6: Equivalent linear circuit diagram of the third stage of the present invention [isolation type]

Figure 7: Second timing diagram of the present invention

Figure 8: The third timing diagram of the present invention

Figure 9: Equivalent linear circuit diagram of the first stage of the present invention [non-isolated type]

Figure 10: Equivalent linear circuit diagram of the second stage of the present invention [non-isolated type]

Figure 11: Fourth timing diagram of the present invention

Figure 12: The present invention The driving signal waveform and , Cross-voltage on switch , Real side waveform [Isolation type D=0.2]

Figure 13: The switch of the present invention and Signal and current Real side waveform [Isolation type D=0.2]

Figure 14: Actual waveform of voltage and current at both ends of the primary and secondary sides of the transformer of the present invention [isolation type D=0.2]

Figure 15: The present invention The driving signal waveform and , Cross-voltage on switch , Real side waveform [Isolation type D=0.7]

Figure 16: Switch of the present invention and Signal and current Real side waveform [Isolation type D=0.7]

Figure 17: Actual waveform of voltage and current at both ends of the primary and secondary sides of the transformer of the present invention [isolation type D=0.7]

Figure 18: Switch of the present invention , The driving signal waveform , Real side waveform [non-isolated D=0.2]

Figure 19: The fourth switch of the present invention Signal Terminal and current Real side waveform [non-isolated D=0.2]

Figure 20: The sixth switch of the present invention Signal Terminal and current Real side waveform [non-isolated D=0.2]

Figure 21: Inductor of the present invention Voltage and current Real side waveform [non-isolated D=0.2]

Figure 22: The fifth switch of the present invention Signal Terminal and current Real side waveform [non-isolated D=0.2]

Figure 23: The third switch of the present invention Signal Terminal and current Real side waveform [non-isolated D=0.2]

Figure 24: The switch of the present invention , The driving signal waveform , Real side waveform [Non-isolated D=0.7]

Figure 25: The fourth switch of the present invention Signal Terminal and current Real side waveform [Non-isolated D=0.7]

Figure 26: The sixth switch of the present invention Signal Terminal and current Real side waveform [Non-isolated D=0.7]

Figure 27: The fifth switch of the present invention Signal Terminal and current Real side waveform [Non-isolated D=0.7]

Figure 28: The third switch of the present invention Signal Terminal and current Real side waveform [Non-isolated D=0.7]

1: Converter

11: First input/output terminal

12:Isolated buck-boost converter

Ci _: Capacitance

N ₁ : Transformer primary side

L _{m 1} : Primary side magnetizing inductance

S ₁ : First switch

N ₂ : Transformer secondary side

L _{m 2} : Secondary magnetizing inductance

S ₂ : Second switch

C ₁ : First capacitor

13: Non-isolated buck-boost converter

S ₃ : The third switch

S ₄ : The fourth switch

L _r : Inductance

S ₅ : Fifth switch

S ₆ : Sixth switch

C ₂ : Second capacitor

14: Second input/output port

Claims (3)

A bidirectional converter is mainly provided with a first input/output terminal, an isolated buck-boost converter, a first capacitor, and a , a non-isolated buck-boost converter and a second input/output terminal; wherein: the first input/output terminal is connected in parallel with the capacitor of the isolated buck-boost converter, the first end of the capacitor of the isolated buck-boost converter is connected to the first end of the primary side of the transformer, the second end of the primary side of the transformer is connected to the first end of the first switch, the second end of the capacitor is connected to the second end of the first switch, and a transformer secondary side is provided corresponding to the primary side of the transformer, the first end of the secondary side of the transformer is connected to the first end of the first capacitor, the second end of the secondary side of the transformer is connected to the first end of the second switch, the second end of the second switch is connected to the first capacitor, and the first end of the second switch is connected to the first capacitor. The non-isolated buck-boost converter is characterized in that the first end of the first capacitor is connected to the first end of the third switch, the second end of the third switch is respectively connected to the first end of the fourth switch and the first end of the inductor, the second end of the inductor is respectively connected to the first end of the fifth switch and the first end of the sixth switch, the second end of the sixth switch is connected to the first end of the second capacitor, the second end of the fourth switch, the second end of the fifth switch and the second end of the second capacitor are all connected to the second end of the first capacitor, and the second capacitor is connected in parallel to the second input/output terminal. A bidirectional converter as described in claim 1, wherein a primary-side magnetizing inductance is formed on the primary side of the transformer. A bidirectional converter as described in claim 1, wherein a secondary magnetizing inductance is formed on the secondary side of the transformer.