TWM467253U - Full bridge AC/DC converter - Google Patents

Description

Full bridge AC/DC converter

This creation is related to AC/DC conversion; in particular, it refers to a full-bridge AC/DC converter.

According to the high-bridge switching mode, the full-bridge AC-DC converter generates a pulse width modulation (PWM) signal to switch the switch rigidly, so as to control the flow of electric energy through different paths, thereby achieving the effect of AC-DC conversion. The above methods often generate a large amount of high-order harmonic currents, which in turn interfere with other devices. Therefore, the selection and design of the AC side filter of the full bridge AC/DC converter becomes quite important.

In general, compared with the traditional L-type filter, the LCL filter is more effective in suppressing high-frequency harmonics under the same inductance value, so it has been gradually applied to devices with high power and low switching frequency. . The signal processing used in the traditional LCL filter circuit is based on a third-order filter. In other words, a low-resistance path is provided through one of the inductors and capacitors for the high-frequency component of the output waveform, thereby reducing the high-frequency component of the current flowing through the other inductor. However, although the LCL type filter has a significant effect on filtering out higher harmonics, the design process of the LCL type filter is cumbersome and requires multiple attempts to find the appropriate parameters. In addition, since the circuit characteristics of the LCL type filter are susceptible to parameters, it is not easy to integrate with other circuits.

In addition, in general, full-bridge AC/DC converters often reduce the size of capacitors and magnetic components by increasing the switching frequency in order to reduce component cost and reduce converter volume. However, increasing the switching frequency of the conversion circuit also increases the switching loss of the switching elements, and also increases the electromagnetic interference (EMI) problem. Therefore, the design of the full-bridge AC-DC converter is still not perfect. There is still room for improvement.

In view of this, the purpose of this creation is to provide a full-bridge AC-DC converter with low electromagnetic interference (EMI), low chopping output voltage, and high conversion efficiency.

In order to achieve the above objective, the present invention provides a full-bridge AC/DC converter for converting AC power of a power source into DC power, supplying power to a load, and the load has a first end and a second end. The full bridge AC/DC converter includes a filter circuit, four switch groups, a first capacitor, a second capacitor, and a first inductor. The filter circuit has an input side and an output side. The input side is electrically connected to the power source, and the output end includes a first output end and a second output end. Each of the switch groups is a first switch group, a second switch group, a third switch group, and a fourth switch group, and each includes an active switch and a diode, and the diode The active switches are connected in parallel, and the negative poles of the diodes form a first end of each switch group, and the anodes of the diodes form a second end of each switch group; wherein the second end of the first switch group The first end of the second switch group is electrically connected to the first end of the first switch group, and the second end of the second switch group is coupled to the filter circuit The second output end is electrically connected; the first end of the third switch group is electrically connected to the second end of the first switch group and the first output end of the filter circuit, and the second switch group is second The end is electrically connected to the second end of the load; the first end of the fourth switch group is electrically connected to the second end of the second switch group and the second output end of the filter circuit, and the fourth switch group is The second end is electrically connected to the second end of the third switch group and the second end of the load. One end of the first capacitor is electrically connected to the first end of the second switch group, and the other end is electrically connected to the first end of the load. One end of the second capacitor is electrically connected to the first end of the load, and the other The terminal is electrically connected to the second end of the load. One end of the first inductor is electrically connected to the first end of the second switch group, and the other end is electrically connected to the first end of the load.

Therefore, through the above design, when performing AC/DC conversion, low electromagnetic interference (EMI), low chopping output voltage, and high conversion efficiency are produced.

11~14‧‧‧ switch group

20‧‧‧Filter circuit

21‧‧‧ Input side

22‧‧‧Output side

221‧‧‧ first output

222‧‧‧second output

S1~S4‧‧‧active switch

D1~D4‧‧‧ Diode

C1~C3‧‧‧ capacitor

L1~L3‧‧‧Inductance

100‧‧‧Power supply

200‧‧‧load

201‧‧‧ first end

202‧‧‧ second end

1 is a circuit diagram of a full-bridge AC/DC converter of the preferred embodiment; FIG. 2 to FIG. 7 are equivalent circuit diagrams of the respective steps; and FIG. 8 is a waveform diagram of input voltage, current, and output voltage.

In order to explain the present invention more clearly, the preferred embodiment will be described in detail with reference to the drawings. Referring to FIG. 1 , a full-bridge AC/DC converter of a preferred embodiment is used to convert AC power of a power source 100 into DC power, and then supply power to a load 200. The load 200 has a first end 201 and A second end 202. The full-bridge AC/DC converter includes four switch groups 11-14, a first capacitor C1, a second capacitor C2, a first inductor L1, and a filter circuit 20. The switch groups 11-14 are respectively a first switch group 11, a second switch group 12, a third switch group 13, and a fourth switch group 14, each of which includes an active switch S1~S4 and In the present embodiment, the active switches S1 to S4 are metal oxide semiconductor field effect transistors (MOSFETs), and of course other transistors or other active switches may be implemented. element. The anodes of the diodes D1 to D4 are electrically connected to the source of the metal oxide semiconductor field effect transistor, and the anode and the metal oxide are The diodes of the semiconductor field effect transistors are electrically connected, and the diodes D1 to D4 are connected in parallel with the corresponding active switches S1 to S4. In addition, the anodes of the diodes D1 to D4 form a first end of each of the switch groups 11-14, and the anodes of the diodes D1 to D4 form a second end of each of the switch groups 11-14. Each of the switch groups 11 to 14 has a connection relationship. The first end of the first switch group 11 is electrically connected to the first end of the second switch group 12. The first end of the third switch group 13 is electrically connected to the second end of the first switch group 11 , and the second end of the third switch group 13 is electrically connected to the second end 202 of the load 200 . The first end of the fourth switch group 14 is electrically connected to the second end of the second switch group 12, and the second end of the fourth switch group 14 and the second end of the third switch group 13 and the load The second end 202 of the 200 is electrically connected.

The first capacitor C1 is a non-polar capacitor, and one end is electrically connected to the first end of the second switch group 12, and the other end is electrically connected to the first end 201 of the load 200. The second capacitor C2 is a non-electrolytic capacitor, and one end is electrically connected to the first end 201 of the load 200, and the other end is electrically connected to the second end 202 of the load 200. One end of the first inductor L1 is electrically connected to the first end of the second switch group 12 , and the other end is electrically connected to the first end 201 of the load 200 .

The filter circuit 20 has an input side 21 and an output side 22, and the input side 21 is electrically connected to the power source 100, and the output side 22 is electrically connected to the switch groups 11-14. In the embodiment, the filter circuit 20 is an LCL type filter circuit, and includes a second inductor L2, a third inductor L3, and a third capacitor C3. One end of the second inductor L2 is electrically connected to one end of the power source 100. One end of the third inductor L3 is electrically connected to the other end of the second inductor L2, and the other end of the third inductor L3 is formed with a first output end 221, and is electrically connected to the first switch group 11 and the Between the third switch groups 12. The third capacitor C3 is electrically connected to the second inductor L2 and the third inductor L3, and the other end is electrically connected to the other end of the power source 100. Connecting, and forming a second output end 222, and electrically connected between the second switch group 12 and the fourth switch group 14.

In this embodiment, the capacitors C1 to C3, the inductors L1 to L3, the input voltage, the input voltage frequency, the switching frequency of the switch groups 11-14, and the resistance value of the load 200 are as follows:

Therefore, through the above-mentioned structural design and specifications, and using the power conversion method described below, the effects of low electromagnetic interference (EMI), low chopping output voltage, and high conversion efficiency can be achieved, and the method includes the following steps, and According to the difference between the power of the power source 100 being a positive half wave or a negative half wave, please refer to FIG. 2 to FIG. 4, when the power of the power source 100 is a positive half wave, the power conversion method includes the following steps:

As shown in FIG. 2, A-1 turns on the active switches S3 and S4 of the third switch group 13 and the fourth switch group 14, and turns off the first switch group 11 and The active switches S1, S2 of the second switch group 12. At this time, the power of the power source 100 is transmitted to the third capacitor C3 through the second inductor L2, and the third capacitor C3 is transmitted through the circuit formed by the third switch group 13 and the fourth switch group 14. The three inductors L3 store energy and resonate the first inductor L1 with the first capacitor C1. In addition, the negative voltage characteristic generated by the resonance of the first inductor L1 and the first capacitor C1 turns on the diodes D1 and D2 of the first switch group 11 and the second switch group 12 to change the circuit configuration. The circuit structure is generated after the third switch group 13 and the active switches S3 and S4 of the fourth switch group 14 and the diodes D1 and D2 of the first switch group 11 and the second switch group 12 are turned on. The electric energy is transmitted to the second capacitor C2 to store energy, and the second capacitor C2 is supplied with power to the load 200 to achieve the effect of reducing the output chopping.

As shown in FIG. 3, A-2 turns on the active switches S1 and S4 of the first switch group 11 and the fourth switch 14 group, and turns off the active switch of the second switch group 12 and the third switch group 13. S2, S3. At this time, the power of the power source 100 is transmitted to the third capacitor C3 through the second inductor L2, and the energy storage of the third capacitor C3 and the third inductor L3 is turned on to turn on the first switch group 11 and the fourth The circuit formed by the switch group 14 is transferred to the resonant circuit of the first capacitor C1 and the first inductor L1 and the second capacitor C2 for energy storage, thereby supplying power to the load 200 to reduce the effect of output chopping.

As shown in FIG. 4, when the energy storage of the third inductor L3 of the filter circuit 20 is reset to zero, the active switches S1 and S4 of the first switch group 11 and the fourth switch group 14 are continuously turned on, and The active switches S2 and S3 of the second switch group 12 and the third switch group 13 are cut off. At this time, the power of the power source 100 is continuously transmitted to the third capacitor C3 through the second inductor L2, and the first inductor L1 and the first capacitor C1 start to resonate to generate a negative power source characteristic, and the second switch group 12 is turned on. And the diodes D2 and D3 of the third switch group 13 change the circuit structure, and pass through the first switch group 11 and the active switches S1 and S4 of the fourth switch group 14 and the second switch group 12 After being electrically connected to the diodes D2 and D3 of the third switch group 13, a circuit structure is generated, and power is transmitted to the second capacitor C2 to store energy, and the second capacitor C2 is supplied to the load 200 to reduce output ripple. The effect.

In addition, each time the steps A-1 to A-3 are performed, the operation of one cycle is completed. Therefore, when the power of the power source 100 is a positive half wave, step A-1 to step A-3 are repeatedly performed until the power source power is changed to a negative half wave, and when step A-1 to step A-3 are performed, The first switch group 11 and the third switch group 13 are turned on or off in a flexible switching manner, and the second switch group 12 and the fourth switch group 14 are turned on or off in a rigid switching manner, thereby achieving Low electromagnetic interference (EMI) and high conversion efficiency.

Referring to FIG. 5 to FIG. 7 , when the power of the power source 100 is a negative half wave, the power conversion method includes the following steps:

B-1, as shown in FIG. 5, turns on the active switches S1 and S2 of the first switch group 11 and the second switch group 12, and turns off the active switch of the third switch group 13 and the fourth switch group 14. S3, S4. At this time, the electricity The power of the source 100 is transmitted to the third capacitor C3 through the second inductor L2, and the third capacitor C3 is stored in the third inductor L3 through a circuit formed by the first switch group 11 and the second switch group 12. Capable of resonating the first inductor L1 with the first capacitor C1. In addition, the negative voltage characteristic generated by the resonance of the first inductor L1 and the first capacitor C1 turns on the diodes D3 and D4 of the third switch group 13 and the fourth switch group 14 to change the circuit configuration. The circuit structure is generated after the first switch group 11 and the active switches S1 and S2 of the second switch group 12 and the third switch group 13 and the diodes D3 and D4 of the fourth switch group 14 are turned on. The electric energy is transmitted to the second capacitor C2 to store energy, and the second capacitor C2 is supplied with power to the load 200 to achieve the effect of reducing the output chopping.

B-2, as shown in FIG. 6, turns on the active switches S2 and S3 of the second switch group 12 and the third switch group 13, and turns off the active switches of the first switch group 11 and the fourth switch group 14. S1, S4. At this time, the power of the power source 100 is transmitted to the third capacitor C3 through the second inductor L2, and the energy storage of the third capacitor C3 and the third inductor L3 is transmitted through the second switch group 12 and the third The circuit formed by the switch group 13 is transferred to the resonant circuit of the first capacitor C1 and the first inductor L1 and the second capacitor C2 for energy storage, thereby supplying power to the load 200 to reduce the effect of output chopping.

B-3, as shown in FIG. 7, when the third inductor L3 of the filter circuit 20 stores zero energy, the second switch group 12 and the third switch group are continuously turned on. The active switches S2, S3 of 13 and the active switches S1, S4 of the first switch group 11 and the fourth switch group 14 are turned off. At this time, the power of the power source 100 is continuously transmitted to the third capacitor C3 through the second inductor L2, and the first inductor L1 and the first capacitor C1 start to resonate to generate a negative power source characteristic, and the first switch group 11 is turned on. And the diodes D1 and D4 of the fourth switch group 14 change the circuit structure, and pass through the second switch group 12 and the active switches S2 and S3 of the third switch group 13 and the first switch group 11 And the diodes D1 and D4 of the fourth switch group 14 are electrically connected to generate a circuit structure, and the power is transmitted to the second capacitor C2 to store energy, and the second capacitor C2 is supplied with power to the load 200 to reduce the output ripple. effect.

In addition, each time the steps B-1 to B-3 are performed, the operation of one cycle is completed. Therefore, when the power of the power source 100 is a negative half wave, the steps B-1 to B-3 are repeatedly performed until the power of the power source 100 changes to a positive half wave, and when steps B-1 to B-3 are performed. The first switch group 11 and the third switch group 13 are turned on or off in a flexible switching manner, and the second switch group 12 and the fourth switch group 14 are turned on or off in a rigid switching manner, thereby Achieve low electromagnetic interference (EMI) and high conversion efficiency.

Therefore, through the design of the above structure and method, as can be seen from FIG. 8, in the present embodiment, the input current I _L2 flowing through the second inductor L2 is transmitted through the LCL when the input voltage V _in peak is about 150V. a case where the action type filter circuit can effectively reduce high frequency ripple, and the DC output voltage V _out is approximately 250V, which flattens the waveform, and an effect of the low output voltage ripple, and thus the second capacitor C2 can be avoided An electrolytic capacitor with a short service life is used to increase the service life of the full-bridge AC/DC converter.

In addition, in actual implementation, the filter circuit of the present invention can also use an L-type filter circuit in addition to the LCL type filter circuit (ie, the filter circuit has only one inductance, and one end of the inductor is electrically connected to one end of the power source 100, and One end forms the first output end 221) and can also achieve the purpose of the present creation. Furthermore, the above description is only a preferred embodiment of the present invention, and variations in the equivalent structure of the present invention and the scope of the patent application are intended to be included in the scope of the present patent.

20‧‧‧Filter circuit

21‧‧‧ Input side

22‧‧‧Output side

221‧‧‧ first output

222‧‧‧second output

S1~S4‧‧‧active switch

D1~D4‧‧‧ Diode

C1~C3‧‧‧ capacitor

L1~L3‧‧‧Inductance

100‧‧‧Power supply

200‧‧‧load

201‧‧‧ first end

202‧‧‧ second end

Claims (8)

A full-bridge AC-DC converter device for converting AC power of a power source into DC power, supplying power to a load, and the load has a first end and a second end; the full-bridge AC-DC converter includes a filter circuit having an input side and an output side, the input side being electrically connected to the power source, and the output end comprising a first output end and a second output end; the four switch groups are respectively one a first switch group, a second switch group, a third switch group, and a fourth switch group, each of which includes an active switch and a diode, the diode is connected in parallel with the active switch, and the The anode of the diode forms a first end of each switch group, and the anode of the diode forms a second end of each switch group; wherein the second end of the first switch group and the first of the filter circuit The output end is electrically connected; the first end of the second switch group is electrically connected to the first end of the first switch group, and the second end of the second switch group is electrically connected to the second output end of the filter circuit Connecting; the first end of the third switch group and the first The second end of the switch group and the first output end of the filter circuit are electrically connected, and the second end of the third switch group is electrically connected to the second end of the load; the first end of the fourth switch group is The second end of the second switch group and the second output end of the filter circuit are electrically connected, and the second end of the fourth switch group is electrically connected to the second end of the third switch group and the second end of the load a first capacitor, one end of which is electrically connected to the first end of the second switch group, and the other end is electrically connected to the first end of the load; a second capacitor, one end of which is electrically connected to the first end of the load, the other end is electrically connected to the second end of the load; and a first inductor, one end of which is electrically connected to the first end of the second switch group The other end is electrically connected to the first end of the load. The full-bridge AC/DC converter of claim 1, wherein the filter circuit includes a second inductor, a third inductor, and a third capacitor; the second inductor is electrically connected to one end of the power source; One end of the third inductor is electrically connected to the other end of the second inductor, and the other end of the third inductor forms the first output end; the third end of the third capacitor is electrically connected to the second inductor and the third inductor The other end is electrically connected to the other end of the power supply and forms the second output end. The full-bridge AC/DC converter of claim 1, wherein the filter circuit includes a second inductor; the second inductor is electrically connected to one end of the power supply, and the other end forms the first output; The other end forms the second output. The full bridge AC/DC converter of claim 1, wherein the first capacitor is a non-polar capacitor. The full bridge AC/DC converter of claim 1, wherein the second capacitor is a non-electrolytic capacitor. The full bridge AC/DC converter of claim 2, wherein the third capacitor is a non-polar capacitor. The full bridge AC/DC converter of claim 1, wherein the active switch is a transistor. The full bridge type AC/DC converting device according to claim 7, wherein the active type The switch is a metal oxide semiconductor field effect transistor (MOSFET).