JPH01114368A - Method of controlling dc/dc converter device - Google Patents

Abstract

PURPOSE:To miniaturize a device and lighten its weight, by switch-working respective switching elements in respective DC/DC converter circuits, mutually with specified phase differences. CONSTITUTION:The control circuit of two-step series connection type DC/DC converter devices is provided with a phase shifter 15, a pulse distributing circuit 17, and gate driving circuits 20, 21, and by the output signal of gate driving circuits 18-21 including the circuits 20-21, the gate turn-ON thyristors GTO11-GTO22 of switching circuits 1, 2 are ignition-phasecontrolled respectively and independently. AC voltage E1, E2 has a period T and a width alpha T/2, and is rectangular wave AC having a phase difference corresponding to T/4 mutually, and added voltage E5 has the period T/4 and comes to the sum voltage of full-wave rectification voltage E3 and E4. Then, it is avoided for the combined value of each output DC voltage to come to zero, and its voltage fluctuation width is reduced. Besides, the desired capacity of a combined voltage smoothing reactor 7 can be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a DC/AC converter circuit.
The present invention relates to a method for controlling a multistage OC/DC converter device that is applied to a DC power supply circuit that has a voltage higher than the rated voltage of a semiconductor element used in a conversion switching circuit and has large voltage fluctuations.

[Conventional technology]

As a conventional control method for this type of multi-stage connected DC/DC converter device, a method is known in which the main circuit of the device illustrated in FIG. 1 is controlled by a control circuit illustrated in FIG. 4. Figure 1 shows an example of a two-stage series-connected DC/DC converter device, where ■ is a switching circuit for DC/AC conversion, and semiconductor switching elements include gate turn-on thyristors GTO1l and GTO, □ and diode D.
It consists of Il, D1□, and capacitors CIl and CIZ.

A transformer 5 transforms the output AC voltage of the switching circuit 1 and supplies the AC voltage E+ to the rectifier circuit 3 at the next stage.

The rectifier circuit 3 is composed of a full-wave rectifier bridge of diodes Dffl to D34, and outputs a DC voltage E. The combination of the switching circuit 1, transformer 5 and rectifier circuit 3 is D.
A unit circuit of the C/DC converter is constituted, and similarly, a combination of the switching circuit 2, the transformer 6, and the rectifier circuit 4 corresponding to each of the above-mentioned circuits also constitutes a unit circuit of the D C/DC converter. Are the positive and negative poles of the switching circuit 1 DC type? The positive terminal of a10 is connected to the positive terminal of the switching circuit 2, and the negative terminal of the switching circuit 2 is connected to the negative terminal of the DC power supply 10, so that the input side of both switching circuits 1 and 2 is connected to the DC power supply. 10 in series. Similarly, the negative electrode of the rectifier circuit 3 is connected to the positive electrode of the rectifier circuit 4, so that the output DC voltages E3 and E4 of the rectifier circuits 3 and 4 are combined in series to form a DC voltage E. Further, the voltage E is smoothed by a voltage smoothing circuit consisting of a beam actuator and a capacitor 8 to become a DC voltage E0, which is supplied to a load 9.

Next, in FIG. 4, the AVR 12, which is an automatic voltage regulator for the DC voltage E0, detects the detected value of the voltage E0 and its set value E by the voltage setting device 13. , and outputs the deviation between the two human forces as an optimally adjusted value both quantitatively and temporally. The phase shifter 14 inputs the output signal of the AVR 12 and the constant frequency reference pulse signal from the oscillator 11, controls the pulse width of the reference pulse signal according to the output of the AVR 12, and adjusts the pulse width to this controlled pulse width. Outputs a pulse signal with the corresponding phase. The pulse distribution circuit 16 receives the output pulse signal of the phase shifter 14, creates two types of pulse signals having a specific phase relationship with the output pulse signal, and sends the pulse signals to the switching circuits 1 and 2. Elements GTO+ + and GTOz+ and GTO
Gate drive circuit 18 for +t and G T Oz z
and 19 are both manually operated. By the pulse signal phase control described above, the switching circuits 1 and 2 generate rectangular wave alternating current voltages E and E which are in phase with each other via transformers 5 and 6.
2, and the smoothed average voltage E0 of the series addition voltage E5 of the full-wave rectified voltages E and E4 of both type voltages is controlled to be equal to the set value E os.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional method, the voltage E, which is the input voltage of the voltage smoothing circuit consisting of the polarizing actuator and the capacitor 8, is a rectangular wave that fluctuates widely as shown in the operating waveform diagram of FIG. 5(e). When the average voltage E0 shown in the figure is obtained from the rectangular wave, the required inductance of the reactor 7 to keep the pulsating component Δ■ of the current IL passing through the reactor 7 within a predetermined value becomes large, and the inductance of the reactor 7 becomes large. 7, the D C/DC converter has also become large and expensive. Furthermore, the fifth
The figure is an operating waveform diagram of each part of the DC/DC converter device, and figures (a) and (b) represent the switching elements G T O+ + in the switching circuits 1 and 2.
and G T Ot r and G T O+ z and G T O
The opening and closing patterns of z and z are shown, and figure (c) is similar to figure (a).
The square wave AC voltage E obtained by the operations shown in and (b)
1 and E2 are shown. Figure (d) shows the full-wave rectified voltage E of each of the AC voltages E and E2 shown in figure (c).

and E4, and the figure (E) shows the added voltage E of the two mold pressures E3 and E4, and the average voltage is indicated by E0 in the figure. figure(
) is the average value of the reactor passing current IL. It shows a pulsating pattern with a width ΔI centered on , the period T is the period of the constant frequency reference pulse signal from the oscillator 11, and α is the zero starting point at the time when the conduction of each switching element starts, and T/ This is a designation coefficient during conduction of each switching element, with 1 at two points in time. Therefore, the voltages E and E2 are rectangular AC waves with period T and αT/2 in half wave.

As described above, in view of the increase in the size of smoothing reactors in the prior art, an object of the present invention is to provide a control method for a multi-stage series-connected DC/DC converter device that makes it possible to downsize the reactor easily and at low cost. That is.

[Means for Solving the Problems] This invention provides means for reducing voltage fluctuations in the rectangular wave DC voltage input to the smoothing reactor in a multistage series-connected DC/DC converter device. That is, a DC/DC system consisting of a semiconductor switching circuit, an isolation transformer, and a diode rectifier circuit.
In a DC/DC converter device consisting of a combination of multiple DC converter circuits and a voltage smoothing circuit consisting of a reactor and a capacitor, the input sides of each of the converter circuits are connected in series to a DC power source. At the same time, each output side is also connected in series to the smoothing circuit, and the switching operation of each of the converter circuits is controlled by giving an appropriate phase difference between the converter circuits.

[Effect]

By adding the rectangular wave output direct current voltages of the unit DC/DC converter circuits constituting the multi-stage series connected DC/DC converter device with an appropriate phase difference without adding them in the same phase, each of the above-mentioned The combined value of the output DC voltage is prevented from reaching zero and decreases during the voltage fluctuation. For example, in the case of a two-stage series-connected converter device, if a phase difference equivalent to 1/4 period of the reference switching frequency is selected as the appropriate phase difference, the composite value of the output voltages will be the output DC voltage of each converter circuit alone. and twice the voltage, and decreases to 1/2 during the voltage fluctuation compared to the time of the in-phase addition. Therefore, by adding the output voltages with a phase difference as described above and reducing the voltage fluctuations of the combined voltage, it is possible to reduce the required capacity of the combined voltage smoothing reactor. In order to perform voltage addition with a phase difference as described above, the present invention provides one set of phase shifter, one pulse distribution circuit, and two sets of gate drive circuits for each switching circuit of each DC/DC converter circuit. An ignition pulse calculation section consisting of an oscillator and a
The output signal of the voltage deviation calculation unit consisting of a VR and a voltage setting device is given to each of the firing pulse calculation units as a common command, and each switching element of the switching circuit is controlled with a predetermined phase difference from each other based on the common command. Each of them is designed to open and close independently.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an example of a main circuit diagram of a two-stage series-connected DC/DC converter device, and FIG. 2 is a control circuit block diagram for the circuit shown in FIG. 1, which shows an embodiment of the present invention. be. FIG. 3 is an operational waveform diagram of each part of the first regeneration circuit controlled by the control circuit of FIG. 2. The main circuit shown in FIG. 1 is commonly used in the prior art.

Further, in FIG. 2, the same reference numerals are given to the same functional components as in the case of the prior art shown in FIG. 4.

FIG. 2 is a control circuit block diagram shown in FIG. 4, in which a phase shifter 15, a pulse distribution circuit 17, and gate drive circuits 20 and 21 are provided, and a gate drive circuit 18 including both drive circuits is provided.
The switching circuits 1 and 2 are controlled by the output signals of ~21.
The firing phases of the semiconductor switching elements GTO, , -GTO, and □ are independently controlled to obtain the operating waveforms shown in FIG. 3. In Figure 3, the figure (
A) to (D) are the switching elements GTO,
.

- This shows the operation pattern in which GTO□2 opens and closes with a time difference of T/4. Here, time T is the period of the constant frequency reference pulse signal from the oscillator 11. Figures (E) and (F) show rectangular wave AC voltages E and E2 obtained by the opening and closing operations shown in Figures (A), (B), (C) and (D), respectively. Figures (G) and (H) respectively indicate the AC voltage E.
, represents the full-wave rectified pressure E2, and E4. Figure
is the pressure E of both molds.

and E, and the average voltage is E in the figure.
Indicated by 0. The figure (N) shows the average value of the passing current (■) of the reactor 7 in FIG. 1. It shows a pulsating pattern with both amplitudes Δl centered on . Here, the alternating current voltages E1 and Et are rectangular wave alternating currents having the period T and the width αT/2, and a phase difference corresponding to time T/4, and the added voltage E is As shown in (2), it has a period T/4 and a width (2).
Between α-1)T/4, it becomes the sum voltage of the voltages E3 and E4, and between width (1-α)T/4, it becomes either one of the voltages E3 or E4, and becomes a fluctuating DC voltage. 0 Next, when the voltage E obtained as described above is smoothed by the voltage smoothing circuit to obtain the average voltage E0, the pulsating component of the current passing through the reactor The required inductance L1 of the reactor to limit the current to Δ■ is given by the following equation (1).

Incidentally, in the case of the prior art shown in FIG. 5(f), the required inductance L2 corresponding to the inductance L1 is given by the following equation (2).

The conduction designation coefficient α in the above equations (1) and (2) sets the required DC voltage E0 of the DC/DC converter device to its set value E. , the switching circuit output transformer 5 of the converter device is automatically changed and controlled according to fluctuations in the DC power supply voltage of the device, and the switching circuit output transformer 5 of the converter device is controlled so that the fluctuation range is 0.5≦α≦1. The transformation ratio of and 6 is determined in advance in accordance with the expected value of the DC power supply voltage fluctuation. Therefore, the maximum values Ll+a and L2em of the inductances L+ and L2 in the variation range of α, the ratio of the two, and the corresponding α value are as shown in the following equation (3).

That is, according to the present invention, the required inductance of the axle can be reduced to about 1/6 compared to the conventional system.

〔Effect of the invention〕

According to the present invention, in a multi-stage series-connected DC/DC converter device, switching elements in each DC/DC converter circuit constituting the device are opened and closed with a predetermined phase difference between them. By increasing the height, the fluctuation of the combined voltage of the output DC voltages of the respective converter circuits is reduced, and the required inductance value of the summation voltage smoothing circuit reactor is significantly reduced, thereby reducing the size of the smoothing reactor, and as a result, the converter The device itself can be made smaller and lighter.

[Brief explanation of the drawing]

FIG. 1 is an example of a main circuit diagram of a two-stage series-connected DC/DC converter device, and FIG. 2 is a control circuit block diagram for the circuit shown in FIG. 1, which is an embodiment of the present invention. Figure 3 is the second
FIG. 3 is an operation waveform diagram of each part of the main circuit corresponding to the control circuit. FIGS. 4 and 5 are examples of prior art corresponding to FIGS. 2 and 3, respectively. 1.2... Switching circuit, 3.4... Rectifier circuit, 5.6... Transformer, 7... Reactor, 8...
Capacitor, 9...Load, 10...DC power supply, 11
...Oscillator, 12...AVR, 13...Voltage setter, 14.15...Phase shifter, 16.17...Pulse distribution circuit, 18-21...Gate drive circuit, CI 1
""' Ct t...Capacitor, D. ~D44...Diode, G T Or I-G T
Otz-Gate Turn-On Sairisk. Figure 3 GTOII, GTO21 Figure 5

Claims (1)

[Claims] 1) A DC/DC converter device consisting of a combination of multiple circuits of a DC/DC converter circuit consisting of a semiconductor switching circuit, an isolation transformer, and a diode rectifier circuit, and a voltage smoothing circuit consisting of a reactor and a capacitor. The input sides of each converter circuit are connected in series to a DC power source, and the output sides of each converter circuit are also connected in series to the smoothing circuit, and the switching operations of each converter circuit are controlled by adjusting a suitable phase difference between the converter circuits. A method for controlling a DC/DC converter device, characterized in that the control method is performed in a controlled manner.