CN2102584U

CN2102584U - Phase-shift controlled dc converter

Info

Publication number: CN2102584U
Application number: CN 91224084
Authority: CN
Inventors: 魏殿忠
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-08-25
Filing date: 1991-08-25
Publication date: 1992-04-22

Abstract

The utility model relates to a phase-shift controlled DC converter which is reversible and transmits energy in two directions. The phase-shift controlled DC converter comprises a power switch, an output transformer and a power switch control circuit, and is characterized in that both ends of the primary pole of the output transformer (8) of the DC inverter are connected in parallel with branch circuits which are formed by connecting semiconductor switches (K1 and K2) in series. The relaying ends of the semiconductor switch (K1) and the switch (K2) and the central tap of the primary pole of the output transformer (8) are used as the input ends of the DC power supply of the DC inverter. Both ends of the secondary pole of the output transformer (8) are connected in parallel with branch circuits formed by connecting semiconductor switches (K3 and K4) in series, and the relaying ends of the semiconductor switch (K3) and the switch (K4) and the central tap of the secondary pole of the output transformer (8) are used as the output ends of the AC power supply of the DC inverter. The two semiconductor switches of the primary pole and the secondary pole of the output transformer are switched on alternately.

Description

Phase-shift controlled dc converter

The utility model relates to a kind of phase shifting control formula direct-flow inverter reversible, the energy transmitted in both directions that has.

The existing direct-flow inverter that is used for uninterrupted power supply adopts the bridge-type direct-flow inverter more, in four switching tubes of direct-flow inverter, there are two switching tubes to be operated in the alternating voltage frequency, two other switching tube is operated in the high frequency state, this power supply is only managed the more advanced PWM technology that adopted, it is also very high that switching frequency is done, response speed is very fast, but the electric current of the output transformer of flowing through is still power current, the size of output transformer and filter can not be dwindled, for reducing output transformer of inverter and filter size, 88 years Hitachi, Ltds have proposed the high-frequency structure of high-frequency inversion-isolating transformer-frequency converter, it is 20KHz by a high-frequency inverter with dc inversion earlier, after the 20KHz high-frequency isolation transformer, is power-frequency voltage by frequency converter with the 20KHz voltage transformation again, what the size of transformer can be done like this is very little, but the sort circuit structure needs two cover control circuits, and, because two HF switch links of series connection make power loss big.

The direct-flow inverter of above-mentioned two kinds of structures all can not the bi-directional energy, for this reason in the Chinese patent 88100162 of Hitachi's application, the input of direct-flow inverter be provided with similar full-bridge type inverter circuit from arc-control device, break-make by each switching tube in arc-control device makes circuit be provided to the regeneration conducting state of DC power supply, DC circuit at the regenerative current that DC power supply is provided to electric power power turn-on state, the load of load and circulates between by the reflux state of short circuit return circuit electric current, thereby reaches two-way energy-delivering function.Sort circuit not only needs the control circuit of three kinds of state time length of control, also needs the variable duration impulse system of control inverter, the structure more complicated.

The purpose of this utility model is to provide a kind of and has output transformer and filter size is little, and control circuit is simple, the high frequency phase shifting control formula direct-flow inverter of energy transmitted in both directions.

Phase shifting control formula direct-flow inverter comprises power switch, output transformer and power switch control circuit, it is characterized in that the elementary two ends of direct-flow inverter output transformer (B) are parallel with semiconductor switch (K ₁, K ₂) series connection branch road, semiconductor switch (K ₁) and switch (K ₂) the handing-over end and the elementary centre cap of output transformer (B) as the dc supply input of direct-flow inverter; The secondary two ends of output transformer (B) are parallel with semiconductor switch (K ₃, K ₄) series connection branch road, semiconductor switch (K ₃) and switch (K ₄) the handing-over end and the secondary centre tap of output transformer (B) as the ac power output of direct-flow inverter; Two elementary and secondary semiconductor switch alternate conduction of output transformer.

For avoiding producing DC component, the semiconductor switch (K at the primary and secondary two ends of output transformer (B) ₁, K ₂, K ₃, K ₄) open with the shutoff cycle select identical, the arbitrary semiconductor switch (K of primary side ₁, K ₂) and the arbitrary semiconductor switch (K of primary side ₃, K ₄) conducting phase difference DT between 0～90 °, change its phase shift adjustment amount D=sin(DT) variation can change inverter output waveform and output voltage.

Semiconductor switch (the K of the primary and secondary both sides of output transformer (B) ₁, K ₂, K ₃, K ₄) switching frequency be far longer than the cut-off frequency and the regulating frequency of inverter output end L-C filter.

Below in conjunction with accompanying drawing the utility model is described in detail.

Fig. 1 is a phase shifting control formula direct-flow inverter structure chart.

Fig. 2 is a phase shifting control formula direct-flow inverter on off state oscillogram.

Fig. 3 is a phase shifting control formula direct-flow inverter working state figure.

Fig. 4 is a phase shifting control formula direct-flow inverter operating state isoboles.

Fig. 5 is phase shifting control formula direct-flow inverter reverse transfer energy-structure figure.

Fig. 6 is phase shifting control formula direct-flow inverter embodiment

Fig. 7 is a phase shifting control formula direct-flow inverter embodiment switch controlled circuit diagram

Fig. 8 is the each point oscillogram of phase shifting control formula direct-flow inverter embodiment switch controlled circuit.

We see from Fig. 1, four power device K₁、K ₂And K₃、K ₄Be separately positioned on former, pair both sides, limit of isolating transformer, these are fully different from conventional bridge-type, semibridge system and push-pull converter structure. Here we stipulate that opening with the shutoff cycle of four switching devices equates (having avoided DC component). At t=a constantly, (Fig. 2), K switch₁Conducting, K₁After opening a period of time DT or phase shift certain angle, K switch₃Open-minded; At the t=b moment, just K₁Open one-period T₁，K ₁Turn-off K₂Open-minded, K₂Open DT after the time, K₃Turn-off K₄Open-minded, so circulation is gone down, and at the rectangular pulse of the A of Fig. 1 point formation one sequence pulse width variability, D is the phase shift adjustment amount here, and modulation voltage and the inverter output voltage value of inverter sine wave depended in its variation, from the whole course of work of inverter, K switch₁、K ₂Open to turn-off and need not any control, as long as ensureing that it was opened with the shutoff cycle equates, and K₃、K ₄Open to turn-off and retrained by D, that is to say by changing D, namely can change inverter output waveforms and output voltage.

Fig. 2 is the on off state oscillogram, and Fig. 2 a is K₁、K ₂On off state, Fig. 2 b is K₃、K ₄On off state, Fig. 2 c are the synthetic pulse width variability voltage signals of A point, and this signal namely is output voltage signal after L-C filtering.

The course of work of Fig. 1 can be used Fig. 3 a, Fig. 3 b, four kinds of equivalent electric of Fig. 3 c, Fig. 3 d The road is described, and further concludes Fig. 3 a and Fig. 3 c, Fig. 3 b and Fig. 3 d and can use respectively Fig. 4 a and Fig. 4 b circuit equivalent.

Now be analyzed as follows, suppose that the transformer internal resistance is r, the load internal resistance is R₀, transformer voltage ratio is n, switching frequency f(1/T), and much larger than cut-off frequency and the regulating frequency of L-C wave filter, according to voltage-dropping type current transformer (buck) State-space Averaging Principle, output voltage is derived as follows:

X＝（i _L1e ₀） ^T（1）

i _L---reactor current

e _O---output voltage

Equivalent electric circuit upstate equation shown in Fig. 4 a and Fig. 4 b is described as:

Fig. 4 a:dX/dt=A ₁X+b ₁E ₁(2)

Fig. 4 b:dX/dt=A ₂X+b ₁E ₂(3)

In the formula:

By these two equations of weighted average, then can get the mean state space equation and be:

dX／dt＝AX＋bE ₁（4）

In the formula

Make dX/dt=0, then can try to achieve the steady-state value of state variable:

X _S＝－A ^－1bE ₁＝

From this expression formula, can derive output voltage E ₀Expression formula (stable state) be

E ₀＝ (E ₁(2D-1))/(n) 1/(1+r/R) （5）

Know at E by (5) formula ₁Under the constant situation, E ₀Size depend primarily on phase shift adjustment amount D, during D=0, E ₀For negative maximum, when D=1/2, E ₀=0, during D=1, E ₀Be positive maximum, if D presses sinusoidal variations, E in the middle of 0～1 ₀Then be a sinusoidal ac signal, this just conforms to we are desired.

Above we have solved energy forward transmitted problem, below we study the reverse transfer problem of energy.

We do some changes slightly with Fig. 1 structure, heavily draw in Fig. 5, and the output end voltage note is made E ₀', output load resistance R move to input be the resistance R seen into from input ', input terminal voltage E then ₁But ' analogy booster type (boost) current transformer utilizes the method for average to be derived as:

E ₁′＝ (nEó)/2D-1 1/(1+r/R(2D-1) ²) （6）

(6) but formula explanation energy transmitted in both directions, therefore, the reactive power of inverter can turn back to the BC end.

Fig. 6 is the embodiment with the phase shifting control formula direct-flow inverter of VDNOS design.Both sides, former pair of limit of transformer power device is served as the energy transmitted in both directions by VDNOS pipe and fast recovery diode.

Fig. 7 is the control circuit of power device among the embodiment, and it is made up of three parts, and a part is a triangular-wave generator, and its frequency of oscillation is a high frequency, is carrier component; A part is that the sine-wave generator frequency of oscillation is a power frequency, and adjustable amplitude value also is controlled by output voltage E ₀, be the modulating wave component; Another part is a phase-shift control circuit.Carrier component and modulating wave component enter the high-speed comparator positive-negative input end simultaneously and obtain and a sinusoidal wave corresponding sequence pulse of different width at output.Waveform is handled with XOR through two divided-frequency is wide as shown in Figure 8, obtains former pair of limit power device drive signal, and the signal that so in principle processing obtains can not definitely guarantee to open with the shutoff cycle and equate.This shortcoming in, among the low capacity UPS, can adopt big carrier wave ratio to be overcome, also can in main inverter structure, adopt similar half-bridge structure, make switching device open and turn-off voltagesecond product and equate.Adopt the control modulation depth to set output voltage E among the embodiment ₀Or stablize E by the FEEDBACK CONTROL modulation depth ₀₁Embodiment is formula work in support, in charging process, utilizes two the VDNOS pipes endophyte fast recovery diode rectification of former limit, carries out constant current floating charge control by charge circuit.Two the VDNOS pipes in former limit this moment are not worked.

At the inverter of real work, for its reliable operation, K is everlasting ₁And K ₂, K ₃And K ₄The switching device conducting with turn-off week during the dead band is set because the existence in dead band, K ₁And K ₂, K ₃And K ₄Open appearance and be interrupted, because surge voltage appears in energy storage in the reactance component.K on the other hand ₁And K ₂, K ₃And K ₄Owing to open and short circuit occurs with the difference of turn-off time or load and in circuit, surge current will take place.Its processing method can adopt capacitance-resistance to absorb, two reactors and go into measure processing such as ring at transformer secondary output leading-out terminal cover magnetic, in general in, these method effects are obvious among the low capacity UPS.

Phase shifting control formula direct-flow inverter is simple in structure, conversion efficiency height, energy energy transmitted in both directions, and inverter is along with the raising of carrier frequency, the isolating transformer volume will dwindle greatly, and this is to reduce the UPS volume, an important channel that make it slimming, reduces the components and parts cost.

Claims

1, a kind of have a phase shifting control formula direct-flow inverter reversible, the energy transmitted in both directions, comprises power switch, output transformer and power switch control circuit, it is characterized in that the elementary two ends of direct-flow inverter output transformer (8) are parallel with semiconductor switch (K ₁, K ₂) series connection branch road, semiconductor switch (K ₁) and switch (K ₂) the handing-over end and the elementary centre cap of output transformer (8) as the dc supply input of direct-flow inverter; The secondary two ends of output transformer (8) are parallel with semiconductor switch (K ₃, K ₄) series connection branch road, semiconductor switch (K ₃) and switch (K ₄) the handing-over end and the secondary centre tap of output transformer (8) as the ac power output of direct-flow inverter; Two semiconductor switch alternate conduction that output transformer is elementary and secondary.

2, phase shifting control formula direct-flow inverter according to claim 1 is characterized in that the semiconductor switch (K at the primary and secondary two ends of output transformer (B) ₁, K ₂, K ₃, K ₄) open identical with the shutoff cycle, the arbitrary semiconductor switch (K of primary side ₁, K ₂) and the arbitrary semiconductor switch (K of primary side ₃, K ₄) conducting phase difference DT between 0～90 °, change its phase shift adjustment amount D=sin(DT) variation can change inverter output waveform and output voltage.

3, phase shifting control formula direct-flow inverter according to claim 1 and 2 is characterized in that the semiconductor switch (K of the primary and secondary both sides of output transformer (B) ₁, K ₂, K ₃, K ₄) switching frequency be far longer than the cut-off frequency and the regulating frequency of inverter output end L-C filter.