JPS63262062A - Inverter main circuit - Google Patents

Abstract

PURPOSE:To reduce a cost by forming only a semiconductor switching element for either one arm of upper and lower arms of an inverter bridge in a high speed switching type and the other in a low speed switching type. CONSTITUTION:An inverter main circuit uses two sets of switching elements EFT1-FET3, BPT1-BPT3 for forming upper and lower arms at the phases of the main circuit bridge, and is composed of a series circuit of it with an inverter load 3. A short period signal is applied to either one of the elements FET1-FET3, BPT1-BPT3, and a long period signal is applied to the other to obtain a predetermined pulse train. In this case, as two sets of the elements, MOS type high speed switching type transistors FET1-FET3 are corresponded to bipolar low speed switching type transistors BPT1-BPT3, the short signal is applied to a high speed side, and the long signal is applied to a low speed signal. Thus, a high speed switching type inverter is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a combination configuration number of semiconductor switching elements of an inverter main circuit.

[Conventional technology]

As a conventional inverter main circuit of this type, the one illustrated in FIG. 5 is known. In Figure 5, transistor elements all having the same switching speed are used as DC voltage switching elements constituting the bridge of the main circuit, 1 is a DC power supply, 2 is a single-phase load, and DI-D4
are freewheeling diodes, BPT I and BPT !
, BPT5, and BPT8 are transistors, and together with the diodes pr-D4, they constitute a single-phase bridge circuit.

[Problem that the invention seeks to solve]

As mentioned above, in the conventional inverter main circuit configuration, the switching speeds of the switching elements constituting the main circuit are all the same. Therefore, in order to increase the frequency of the inverter output AC, the switching speed of all the switching elements must be It is necessary to increase the speed of the system, which is currently extremely expensive. In view of this, an object of the present invention is to provide an inverter main circuit that is capable of high-speed switching and is inexpensive.

[Means for solving problems]

Each phase switching element of the main circuit of the bridge structure of the inverter is a combination of high-speed and low-speed switching type elements, and switching operations are performed using different frequency signals according to the characteristics of each element. That is, in a main circuit of a bridge configuration using semiconductor switching elements of an inverter that receives DC input and converts the DC into AC having arbitrary frequency and voltage, two sets forming the upper and lower arms of the bridge from the positive terminal side of the DC input. Each phase of the AC output is energized to the negative electrode side of the DC input via a series circuit consisting of a semiconductor switching element of the inverter and a load of the inverter. A low-speed switching element that switches the two sets of semiconductor switching elements in the flow path for each phase of the bridge using a reference frequency signal of the AC output, and a high-speed switching element that switches the two sets of semiconductor switching elements in the flow path using a carrier wave signal for pulse width modulation, etc. The device is characterized in that it is configured by an element.

[Effect]

The basic circuit of the inverter main circuit is a series circuit of two sets of switching elements forming upper and lower arms of each phase of the main circuit bridge and an inverter load. Therefore, the output of the basic circuit is obtained as a result of ANDH calculation of the two sets of switching elements. Therefore, when outputting a pulse train that has a period within the range of the basic circuit and has been subjected to intermittent modulation with a period shorter than the period, the two sets of switching signals are controlled by only the short period signal of the two types of long and short switching signals. It is not necessary to switch the elements simultaneously, and a predetermined pulse train can be obtained by applying the short period signal to one of the two sets of switching elements and applying the longest period signal ad to the other element. In the present invention, a high-speed switching type element and a low-speed switching element are made to correspond to each other as the two sets of switching elements of the basic circuit, and a carrier wave signal for pulse width modulation is made to correspond to the ml periodic signal, so that the high-speed switching type element Furthermore, as the long period signal, a reference frequency signal of the AC output of the inverter is added to the low speed switching element to obtain a predetermined pulse train.

〔Example〕

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

1 and 3 relate to a single-phase inverter, FIG. 4 relates to a three-phase inverter, and is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is an operating waveform diagram of the circuit shown in FIG. 1.

Note that in FIGS. 1, 3, and 4, the same reference numerals are given to components having the same functions as in the prior art embodiment shown in FIG. 5. In Figure 1, 1 is DC 1! source, 2 is a single-phase load, ]) I-D4 is a freewheeling diode, BPTI and BPT2 are low-speed switching transistors such as bipolar type, FETI
FET2 is a high-speed switching transistor such as a MOS type transistor, and each transistor constitutes a single-phase bridge circuit together with the diodes D1 to D4.

Therefore, the current path from the positive electrode side of the DC power supply 1 to its negative electrode side is one that passes through the transistor FET l, the single-phase load 2, and the transistor BPT2.
There are two ways: via the transistor BPTI, the single-phase load 2, and the transistor FET2.
Combination of ETI and BPT2 and BPTI and FET 2
The combinations thereof constitute an AND circuit regarding power supply to the single-phase load 2 during each switching operation. FIG. 2 shows operating waveforms of each transistor when a switching signal is applied to each transistor in the circuit shown in FIG. 1 so that the circuit as a whole performs an inverter operation. ON state and OFF state shown in Figures (a) to 2)
A state indicates a conduction state or a cutoff state of a corresponding transistor. Figures (a), (b), (c), and (b) are the transistors FET 1, FET 2) B, respectively.
The ON-OFF operating state of PTl and BPT2 is shown.

Therefore, the combination of Figure ■ and Figure) and Figure (B) and Figure? ), power is supplied from the DC power supply 1 to the single-phase load 2 during the common ON period of each combination, and as shown in Figure (G), the single-phase load 2
*An output voltage Vo is given to this. The output voltage VO is connected to the low-speed switching terminal B according to the energization path shown in FIG.
Due to the low-speed switching operations of PTt and BPTz, the voltage applied to the single-phase load 2 becomes an alternating current whose polarity is alternately reversed. Figures ■ and Figure 0 are high-speed switching transistors FE for pulse width modulation carrier signals, respectively.
The switching response pattern in which the ON-OFF period of T1 and FET2 is reversed is shown, and FIG. 0 and FIG.
The switching response pattern is shown in which the ON-OFF period is inverted with respect to rz. Furthermore, the above-mentioned pulse l'
The fluctuation period of the pulse train of the modulation carrier signal is equal to the period of the reference frequency signal of the impark AC output. Next, Fig. 3 shows the main circuit of a single-phase inverter, which has the same function as the circuit shown in Fig. 1, and its operating pattern is also the same as the operating waveform diagram shown in Fig. Unlike Figure 1, the two sets of switching elements forming the upper arm of the bridge of the inverter main circuit are replaced by high-speed switching transistors I''.
ET1 and FET2, and the two sets of switching elements that also form the lower arm are low-speed switching transistors BPT1 and BPT2. An AND circuit is formed by a high-speed switching transistor and a low-speed switching transistor. FIG. 4 is a circuit diagram of the main circuit configuration of a three-phase inverter in which the arm configuration of the inverter main circuit shown in FIG. 3 is enlarged, and its operation pattern can be similarly estimated based on the case shown in FIG. 2.

〔Effect of the invention〕

According to the present invention, in a main circuit of an inverter having a bridge configuration using semiconductor switching elements, only the semiconductor switching element for the arm configuration on either the upper or lower side of the bridge configuration is of the high-speed switching type, and the other arm elements are of the low-speed switching type. As a form, by performing appropriate switching control on the semiconductor switching elements for forming both the upper and lower arms, a high-speed switching type inverter having the same function as when both the semiconductor switching elements for forming both the upper and lower arms are of high-speed switching type can be obtained. This makes it possible to significantly reduce the price of semiconductor switching elements for the main circuit, which account for a large proportion of the inverter price.

[Brief explanation of the drawing]

1 and 3 relate to a single-phase inverter, FIG. 4 relates to a three-phase inverter, and is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is an operating waveform diagram of the circuit shown in FIG. 1. Fifth
The figure is a circuit diagram showing an example of the prior art. 1...DC power supply, 2...Single-phase load, 3...Three-phase load, BPTI~l3PT 8...Bipolar transistor, FET1~FET! l...MO8 type transistor,])+-1)g...freewheel diode. /--N

Claims (1)

[Scope of Claims] 1) In a main circuit of a bridge configuration using semiconductor switching elements of an inverter that receives DC input and converts the DC into AC having arbitrary frequency and voltage, the bridge is connected from the positive terminal side of the DC input to the bridge. The two sets of semiconductor switching elements in each phase current path of the AC output that conducts current to the negative electrode side of the DC input via a series circuit consisting of the two sets of semiconductor switching elements constituting the upper and lower arms and the load of the inverter. is characterized in that each phase of the bridge is constituted by a low-speed switching element that is switched by a reference frequency signal of the AC output, and a high-speed switching element that is switched by a carrier wave signal for pulse width modulation, etc. Main circuit of the inverter. 2) In the inverter main circuit according to claim 1, the two sets of upper and lower arms in the single-phase bridge circuit are
The main circuit of the inverter has one set of two high-speed switching elements connected in series, and the other set of two low-speed switching elements connected in series.