TW201308840A - Active damping circuit capable of performing soft-switching - Google Patents

Abstract

An active damping circuit capable of performing soft-switching comprises a bidirectional transducer and an active damper. The bidirectional transducer is connected between an input power source and a load end. The bidirectional transducer includes at least a voltage boost circuit, a voltage reduction circuit and a filtering inductor, wherein the filtering inductor is disposed between the voltage boost circuit and the voltage reduction circuit while a reverse recovery current is generated when the voltage boost circuit and the voltage reduction circuit make the switch. The active damper is connected with the filtering inductor of the bidirectional transducer in parallel. Accordingly, when the voltage boost circuit and the voltage reduction circuit make the switch and generate the reverse recovery current, the active damper provides an energy recovery path to the load end, so as to release the energy of the filtering inductor and thereby solve the problem of surge voltage generated during the switch process of the transducer. As a result, the transduction efficiency of the whole circuit is improved.

Description

Active vibration-damping circuit capable of flexible switching

The invention relates to an active type vibration damping circuit, in particular to an active type vibration damping circuit which can be flexibly switched in parallel with a bidirectional converter to reduce voltage and current stress during switching, and improve conversion efficiency.

With the advancement of technology, the stability of power quality has gradually received attention. The backup power system has important functions in regulating power load and power supply systems to adjust load fluctuations and reduce power demand.

Based on environmental awareness and power reliability considerations, decentralized power generation systems using diversified renewable energy sources have begun to receive attention. Therefore, it is necessary to adjust the intermittent supply of renewable energy power generation facilities to meet the continuity requirements of power supply. An integral part of the system.

In general, the backup power system has a charger, a discharger, and a battery to achieve the desired basic functions. When the voltage of the high-voltage DC busbar is normal, the main power supply provides the energy required by the load, and simultaneously charges the battery through the charger; if the voltage of the high-voltage DC busbar is insufficient, the battery supplies the required energy to the busbar via the discharger, Maintain normal load operation. The prior art utilizes the function of the bidirectional switch to integrate the charger and the discharger into a bidirectional DC/DC converter (Bi-directional DC/DC converter), and the integrated system block diagram can be simplified as shown in FIG. This whole system, including mains or renewable energy 1, DC converter 2, load 3, bidirectional DC/DC converter 4 and battery 5, can save power switch and drive circuit, thus reducing the size, weight and cost. In line with the current trend of light, thin, short, small and digital in power electronic systems, the overall practicality is improved.

2 is a schematic diagram of the internal circuit of the bidirectional DC/DC converter 4 and the battery 5 according to FIG. 1, in which the switching elements S ₁ and S _{2 in} FIG. _{2 are} commonly used in consideration of cost and high frequency switching. It is realized by a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET). However, since the interior of the MOSFET body diode (body diode) has a long reverse recovery time (reverse recovery time), so when the MOSFET is likely to cause a large reverse restoring current, this current will flow through the switching element S ₁ , S ₂ , and produce high current stress.

To solve this problem, as shown in FIG. 3, the prior art further incorporates a filter inductor L _r (<<L _m ) to limit current in the circuit. However, it is worth noting that in the boost mode operation, when the switching element S ₂ is turned off, the current flowing through L _m and L _r is different, and a large amount of voltage surge is generated across the switching element S ₂ . This reduces the conversion efficiency and reliability of the overall circuit.

Therefore, how to solve the problem of high voltage and high current stress of the above switch and to achieve the near zero current switching (ZCS) technology in the circuit is urgently needed to be solved by those skilled in the art. One of the problems.

The main object of the present invention is to provide an active type vibration damping circuit capable of flexible switching, which can reduce the voltage surge generated by the filter inductor and recover the energy of the filter inductor to the load end to increase the efficiency of the overall circuit system. .

Another object of the present invention is to provide an active type vibration damping circuit capable of flexible switching, which can solve the high voltage and high current stress generated by the bidirectional converter during off-state switching, and achieve approximately zero voltage and zero. Flexible switching technology for current.

In order to achieve the above object, the present invention relates to an active vibration damping circuit capable of flexible switching, comprising: a bidirectional converter and an active vibration damper. The bidirectional converter is connected between an input power and a load terminal. The bidirectional converter includes at least a boosting circuit, a step-down circuit and a filter inductor, wherein the filter inductor is disposed between the booster circuit and the step-down circuit, and the booster circuit and the step-down circuit switch to generate a reverse return current.

The active damper is connected in parallel to the filter inductor of the bidirectional converter. Thereby, when the boost circuit and the buck circuit switch to generate a reverse recovery current, the active damper provides an energy recovery path to the load terminal to release the energy of the filter inductor.

According to an embodiment of the invention, the active damper may be a flyback converter or an isolated converter.

The purpose, technical contents, features and effects achieved by the present invention will be more readily understood by the detailed description of the embodiments and the accompanying drawings.

The invention provides an active type vibration damping circuit capable of flexible switching. The bidirectional converter is combined with an active vibration damper, which can effectively improve the high voltage and large current stress generated by the power switch in the circuit, and achieve flexible switching. At the same time, the noise interference generated by the bidirectional converter during hard switching is avoided, so that the system has better conversion efficiency and reliability.

Please refer to FIG. 4, line according to an embodiment of the present invention, a schematic view of the active type snubber circuits soft switching of the available which includes a connection to the input bidirectional converter between the power V _H and the load terminal V _L 22, and a Active damper 20.

The bidirectional converter 22 includes a booster circuit 10, a buck circuit 12 and a filter inductor L _r . The filter inductor L _{r is} coupled between the boost circuit 10 and the buck circuit 12 for filtering the current limit. In accordance with an embodiment of the present invention, when the boost circuit 10 of the bidirectional converter 22 and the buck circuit 12 are power switched, the bidirectional converter 22 generates a reverse recovery current.

The active damper 20 is connected in parallel to the filter inductor L _r . Thus, according to an embodiment of the present invention, the booster circuit 10 when the step-down switching circuit 12 generates an inverse restoring current, active vibration buffer system 20 provides an energy return path to the load terminal V _L, to the filter inductor L _r The energy is released.

According to an embodiment of the present invention, the active damper 20 includes a switching element S _a , a transformer T and a diode D _b , which may be, but not limited to, a flyback converter and an isolated converter. (Isolated converter), or other types of converters. The designer can generally determine it according to the actual circuit requirements, and only the converter type of the active damper 20 is not intended to limit the scope of the invention.

The energy recovery path referred to in the embodiment of the present invention is mainly composed of an active damper 20, an auxiliary diode D _a and an auxiliary capacitor C _a . As shown in FIG. 1, the auxiliary capacitor C _a is connected in parallel to the filter inductor L _r , and the auxiliary diode D _{a is} connected between the auxiliary capacitor C _a , the filter inductor L _r and the active damper 20 .

Still further, the present invention proposes an energy return path, wherein D _a secondary auxiliary capacitor C _a diode connected to the line side of the secondary of the active snubber 20 (auxiliary side), and V _L is connected to the load line terminal The secondary side of the active damper 20. Therefore, the active damper 20 proposed by the present invention recovers the spur energy generated by the bidirectional converter 22 on the filter inductor L _r at the time of switching to the load on the secondary side thereof by the energy recovery path. End V _L .

It can be seen that the architecture proposed by the present invention can not only solve the high voltage and large current stress problems generated by the bidirectional converter between the switches, but also further improve the conversion efficiency of the circuit by recovering energy to the secondary side of the converter. .

In detail, the step-down circuit 12 includes a first switch S ₁ and a first reverse diode D ₁ . The first switch S ₁ may be, for example, a p-type metal-oxide-semiconductor field-effect transistor (MOSFET), and the first switch S ₁ is connected to the input power V _H and the filter inductor. Between L _r and the first reverse diode D ₁ is connected in parallel with the first switch S ₁ .

The boosting circuit 10 includes a second switch S ₂ , a second reverse diode D ₂ and a main inductor L _m , wherein the second switch S ₂ can be, for example, a p-type metal oxide semiconductor field effect transistor. (MOSFET), the second switch S _{2 is} connected between the filter inductor L _r and a ground GND, the second reverse diode D _{2 is} connected in parallel with the second switch S ₂ , and the main inductor L _{m is} connected to the filter inductor L _r between the load terminal and the V _L.

Continued to Figure 5, which is a schematic diagram of the voltage and current waveforms of the circuit architecture shown in Figure 4. Where V _GS1 is the gate-source voltage difference of the first switch S ₁ , V _GS2 is the gate-source voltage difference of the second switch S ₂ , and V _GSa is the switching element S _a of the active damper 20 Gate-source voltage difference, I _Lr is the current flowing through the filter inductor L _r , I _Lm is the current flowing through the main inductor L _m , I _DS1 is the current flowing through the first switch S ₁ , I _DS2 For the current flowing through the second switch S ₂ , V _DS1 is the 汲-source voltage difference of the first switch S ₁ , and V _DS2 is the 汲-source voltage difference of the second switch S ₂ .

As described above, the bidirectional converter 22 of the embodiment of the present invention includes a boosting circuit 10 and a step-down circuit 12, wherein the step-down circuit 12 is used for performing charging, and the boosting circuit 10 is configured to perform discharging. use. Therefore, for the detailed description, please refer to FIG. 4 and FIG. 5 together below, and the two operation modes are described as follows.

The buck circuit 12 performs a charging mode:

Stage one [t0 t<t1]: In this mode, the first switch S ₁ can be turned on with approximately zero current due to the current limit of the filter inductor L _r . The input power V _H charges the main inductor L _m and the filter inductor L _r , because L _r <<L _m , the current I _Lr flowing through the filter inductor L _r rises rapidly until I _Lr =I _Lm . Because of the current I _Lr and I _Lm current difference, the second reverse diode D ₂ will continue to conduct, causing a slight drop in the current I _Lm .

Stage two [t1 t<t2]: In this mode, the current I _Lr flowing through the filter inductor L _r is equal to the current I _Lm flowing through the main inductor L _m such that the main inductor current I _Lm and the filter inductor current I _Lr rise simultaneously.

Stage three [t2 t <t3]: at time t2, the first switch S ₁ is about to cut, L _r of the filter inductor current I _Lr flowing through a continuous flow, the auxiliary capacitor C _a and D _a flow through the auxiliary diode. When the first switch S ₁ is turned off by the current of the main inductor L _m continuously, the second switch S of the second diode D ₂ reverse conduction _2, this time the second switch S ₂ is turned on, so the synchronous rectifier can be Reduce conduction losses. Therefore, when the first switch S _{1 is} turned off and the second switch S _{2 is} turned on, the energy of the filter inductor L _r is stored in the auxiliary capacitor C _a , and then returned to the low voltage load terminal V _L by the active moderator 20 . .

Stage four [t3 t<t4]: The current I _Lm flowing through the main inductance L _m continues to drop until the next cycle to turn on the first switch S ₁ at time t4.

The booster circuit 10 performs a discharge mode:

Stage one [t0 t <t1]: In this mode, since the current in the filter inductor L _r a continuous flow, a first switch S ₁ is turned off, but the first reverse diode D ₁ is still turned on, so in this case the second switches S _{2 The} approximate zero current conduction can be achieved, so that the low voltage load terminal V _L charges the main inductor L _m and the main inductor current I _Lm rises. The current I _Lr flowing through the filter inductor L _r then continues to drop to zero via the first reverse diode D ₁ and the input power V _H , and the active damper 20 begins to operate to transfer the energy stored by the auxiliary capacitor C _a To the low voltage end V _L .

Stage two [t1 t<t2]: The main inductor current I _Lm continues to rise until the second switch S _{2 is} turned off.

Stage three [t2 t<t3]: When the time t2 arrives, the second switch S ₂ is turned off. A first switch S of the first diode D ₁ reverse conduction of _1, while the first switch S ₁ is turned on, so the synchronous rectifier. Therefore, when the second switch S _{2 is} turned off and the first switch S _{1 is} turned on, the current difference between the main inductor L _m and the filter inductor L _r will flow to the auxiliary capacitor C _a , so that the filter inductor current I _Lr rises rapidly, and the main inductor The current I _Lm begins to drop until the main inductor current I _{Lm is} equal to the filtered inductor current L _r .

Stage four [t3 t<t4]: When the main inductor current I _{Lm is} equal to the filter inductor current L _r , the main inductor L _m and the filter inductor L _{r are in} series, and then the main inductor current I _Lm and the filter inductor current L _r are The two switches S _{2 are} turned on again until the next cycle.

Therefore, in summary, the active slow-vibration circuit capable of flexible switching disclosed in the present invention can not only greatly improve the system efficiency and reliability of the bidirectional converter, but also achieve switching between approximately zero voltage and zero current.

Applying the active damper disclosed in the present invention, when the first switch and the second switch switch to generate a reverse return current, the reverse return current will not flow through the main switch of the bidirectional converter (ie, the first switch and the second switch) ), and will be recovered to the low-voltage load via the energy recovery path provided by the active damper to further recover energy and improve circuit conversion efficiency.

The embodiments described above are merely illustrative of the technical spirit and the features of the present invention, and the objects of the present invention can be understood by those skilled in the art, and the scope of the present invention cannot be limited thereto. That is, the equivalent variations or modifications made by the spirit of the present invention should still be included in the scope of the present invention.

V _H . . . Input power

GND. . . Ground terminal

V _L . . . Load side

C _a . . . Auxiliary capacitor

T. . . transformer

D _b , D _a , D ₁ , D ₂ . . . Dipole

S _a , S ₁ , S ₂ . . . Switching element

L _r , L _m . . . inductance

1. . . Mains or renewable energy

2. . . DC converter

3. . . load

4. . . Bidirectional DC/DC converter

5. . . Battery

10. . . Boost circuit

12. . . Buck circuit

20. . . Active damper

twenty two. . . Bidirectional converter

Figure 1 is a block diagram of a power system of the prior art.

Fig. 2 is a schematic diagram showing the internal circuit of the bidirectional DC/DC converter and the battery according to Fig. 1.

Figure 3 is a schematic diagram of a circuit incorporating a filter inductor in accordance with the circuit architecture of Figure 2.

Figure 4 is a schematic diagram of an active mode vibration-supplied circuit that can be flexibly switched in accordance with an embodiment of the present invention.

Figure 5 is a schematic diagram of voltage and current waveforms according to the circuit architecture shown in Figure 4.

V _H . . . Input power

GND. . . Ground terminal

V _L . . . Load side

C _a . . . Auxiliary capacitor

T. . . transformer

D _b , D _a , D ₁ , D ₂ . . . Dipole

S _a , S ₁ , S ₂ . . . Switching element

L _r , L _m . . . inductance

10. . . Boost circuit

12. . . Buck circuit

20. . . Active damper

twenty two. . . Bidirectional converter

Claims (12)

An active vibration damping circuit capable of flexible switching, comprising: a bidirectional converter connected between an input power and a load end, the bidirectional converter comprising at least a boost circuit, a buck circuit and a filter inductor The filter inductor is disposed between the booster circuit and the buck circuit, and the booster circuit and the buck circuit switch to generate a reverse return current; and an active moderator is connected in parallel to the filter inductor. When the boost circuit and the buck circuit switch to generate the reverse recovery current, the active damper provides an energy recovery path to the load terminal to release the energy of the filter inductor. The active moderating circuit capable of flexible switching, as described in claim 1, wherein the active moderator is a flyback converter. The active moderator circuit capable of flexible switching, as described in claim 1, wherein the active moderator is an isolated converter. The active mode vibration-suppressing circuit as described in claim 1, wherein the energy recovery path is composed of the active moderator, an auxiliary diode and an auxiliary capacitor, and the auxiliary capacitor is connected in parallel with the filter inductor. And the auxiliary diode is connected between the auxiliary capacitor, the filter inductor and the active damper. The active vibration-damping circuit capable of flexible switching, wherein the auxiliary diode is connected to the auxiliary side of the active damper, and the load end is connected to the active damper. Secondary side. The active mode vibration-suppressing circuit as claimed in claim 1, wherein the step-down circuit comprises a first switch and a first reverse diode, the first switch being connected to the input power and the filtering Between the inductors, and the first reverse diode is connected in parallel with the first switch. An active mode vibration damper circuit capable of flexible switching, as described in claim 6, wherein the first open relationship is a metal oxide semiconductor field effect transistor. The active mode vibration-suppressing circuit as described in claim 6, wherein the boosting circuit comprises a second switch, a second reverse diode and a main inductor, and the second switch is connected to the filter Between the inductor and a ground, the second reverse diode is connected in parallel with the second switch, and the main inductor is connected between the filter inductor and the load end. An active mode vibration damper circuit capable of flexible switching, as described in claim 8, wherein the second open relationship is a metal oxide semiconductor field effect transistor. The active mode vibration-suppling circuit capable of flexible switching, as described in claim 8, wherein when the first switch is turned off and the second switch is turned on, the energy of the filter inductor is released to the load end via the energy recovery path. . The active mode vibration-suppressing circuit as described in claim 8, wherein when the second switch is turned off and the first switch is turned on, a current difference between the filter inductor and the main inductor flows to the auxiliary capacitor until the The filter inductor is equal to the current of the main inductor. The active mode vibration-suppling circuit capable of performing flexible switching, as described in claim 8, wherein when the first switch and the second switch switch to generate the reverse recovery current, the reverse recovery current does not flow through the first switch and The second switch is recovered to the load end by the energy recovery path.