JPH02231965A - Constant voltage/constant frequency power supply equipment - Google Patents

Abstract

PURPOSE:To make high pressureproof nonstandard components unnecessary by connecting one of AC power input parts between rectifying elements of a converter circuit to convert AC power input DC voltage and by smoothing said DC voltage through a smoothing capacitor to convert said voltage into AC voltage through an inverter circuit. CONSTITUTION:As diodes 1 are connected in series in the same direction, a current can be rectified. A DC voltage obtained in this manner is smoothed by a smoothing circuit B so that a DC voltage with a ripple component of less than several % is obtained. When an input voltage is positive, a switching circuit 6 is turned ON to control the positive half cycle of output voltage. When the input voltage is negative, said switching circuit 6 is turned ON to control the negative half cycle of said output voltage. Said DC voltage is converted into an AC power with specified voltage and frequency by an inverter circuit C.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a constant voltage/constant frequency power supply device used for speed control of a small single-phase induction motor, a computer, etc. When the voltage is 200 V class or higher, circuit elements need to have a large withstand voltage, so this invention relates to improving this withstand voltage.

[Conventional technology]

An example of a conventional power supply device will be explained based on FIG. 5.

The figure was proposed by the applicant in Japanese Patent Application No. 62-148666, and in this figure, (A) is a converter circuit, which is formed by connecting two diodes in series.

ω) is a smoothing circuit connected in parallel to the converter circuit (A), and is formed by two capacitors connected in series.

(C) is an inverter circuit connected to the smoothing circuit CB), which is composed of two switching elements (3) connected in series.

This switching element (3) fl, } transistor (3t
) are each constituted by a flywheel diode (8d) which is connected between the collector and emitter of the t-t-.

One of the single-phase AC voltage power input parts (5) is connected to the 111 in the two diodes (1) of the converter circuit @).
connected to.

1, one side of the power output section (6) is an inverter circuit (C
) is connected to the middle part of the two switching elements (3).

The other power input section (5) and the other power output section (6) are connected by one connection line. This connection 4i! is grounded and switch (4) t-
is connected to the middle part of the two capacitors (2) of the smoothing circuit.

Next, the operation will be explained.

A single-phase AC voltage is input from a power input section (5), and one of the power input sections (5) is connected to one of the power output sections (6) by a single connection line. Since this connecting line is grounded, it is held at a predetermined potential.

The other end of the power input part (5) is connected to the intermediate part of the two diodes (1) of the converter circuit (A) by a connecting line.

Since the diodes (1) are connected in series facing the same direction, the current flows only upward in the figure and is rectified. Then, the DC voltage containing a large Rigg μ component obtained in this manner is smoothed by a smoothing circuit (equalizing circuit). As a result, a DC voltage with a Lidde μ component of several percent or less is obtained.

This DC voltage is converted into AC power of a predetermined voltage and frequency by an inverter circuit (C). Switching in this inverter circuit (C) is performed, for example, by the following PWMI1 control. This PWM control obtains AC power of a predetermined voltage and frequency by modulating and controlling the @ of the pulse applied to the base of the transistor (8t).

The upper diagonally shaded part in Figure 6 K is! The conduction state of the switching element (3) on the opposite side in Figure 5! The lower diagonally shaded portion in FIG. 6 indicates the conduction state of the lower switching element (3) in FIG. 5. By such switching control, output power having a waveform as shown by curve (7) in FIG. 6 can be obtained.

Here, the DC voltage N Vpl output from the smoothing circuit is 2Ed ranging from Ed to -Ed. When the switch (4) is in the on state, the potential at the midpoint of the smoothing circuit becomes Ov, which is exactly between Ed and -Ed. Note that the switch (4) is connected to the power input section (5).
) When connecting the power supply and the power output section (6) to a load such as a t-motor, turn it off.

[Problem to be solved by the invention]

The conventional constant voltage/constant frequency power supply device is w4 as described above.
For example, when the voltage waveform is in the range of the slope shown in Figure 7 (6), the current flows as shown in Figure 7 (b). When the voltage waveform is in the range @, the current flows as shown in Figure 7 (C). Therefore, as shown in Figure 6, there is a DC voltage of (mu × 100 10 - XIOO) V between ``-IPN''. Therefore, the PN voltage between PN will be 282.8V.DC voltage 2
When converted to AC by 82.8Vt-PWM inverter control, the output voltage is 87.8V. As mentioned above, in order to obtain the output voltage t-ioov, 282.8X
A DC voltage between 100/87.8=822.1 and N is required.

Output voltage (6) If you want to obtain t-200V or more, }'N[
A pressure of 640 cm or higher is required. Output voltage (6)'k
There is no particular problem if you want to obtain about 100V, but 2
If you want to obtain more than 00■, use 100■
A product with a withstand voltage that is at least twice that of a class-grade product is required.

For this reason, the elements used are components for high withstand voltages, for example, IOOOV or higher, which lack versatility and are expensive. Furthermore, since the circuit configuration is at high voltage, it is necessary to consider the insulation distance between the parts. Problems arose, such as the overall configuration becoming large and, by extension, the device itself becoming large.

This invention was made to solve the above-mentioned INIIMt-, and even if the output voltage is in the t-200 V class, it is possible to achieve a constant voltage/constant frequency configuration without using special components for high withstand voltage. The purpose is to obtain a power supply device.

[Means to solve the problem]

A constant voltage/constant frequency power supply device according to a first aspect of the present invention includes a converter circuit that receives AC power and converts it into DC power, and an input unit that converts the DC power output from the converter circuit into predetermined AC power. /In the power supply device having a parter circuit, the converter circuit is configured by connecting at least two rectifying elements in series, and the inverter circuit is configured by connecting at least two rectifying elements in series. A smoothing capacitor is connected to the converter circuit, and a changeover switch section consisting of at least two switching circuits each consisting of a rectifying element and a switching element is connected in parallel to the converter circuit and the inverter circuit. one of the pair of AC power input parts is connected between the rectifying elements forming the converter circuit, one of the pair of AC power output parts is connected between the switching circuits forming the inverter circuit, and one of the pair of AC power input parts is connected between the switching circuits forming the inverter circuit. The other of the AC power input sections and the other of the pair of AC power output sections are connected by a common line, and the switching circuits forming the changeover switch section are connected to the common line.

A constant voltage/constant frequency power supply device according to a second invention includes a converter circuit that receives AC power and converts it into DC power, and an inverter that converts the DC power output from the converter circuit into predetermined AC power. In the power supply device having a circuit, the converter circuit is configured by connecting at least two switching circuits each including a rectifying element and a switching element in series, and the inverter circuit is configured by connecting at least two switching circuits each including a rectifying element and a switching element in series. A smoothing capacitor is connected to the converter circuit, and at least two switching circuits each consisting of a rectifying element and a switching element are connected in series. one of the pair of AC power input sections is connected in parallel between the switching circuits constituting the converter circuit described above, and one of the pair of AC power output sections is connected between the switching circuits constituting the above converter circuit. The other of the pair of AC power input units and the other of the pair of AC power output units are connected by a common line, and the switching circuits constituting the changeover switch unit are connected to the common line. It is something.

A constant voltage/constant frequency power supply device according to an eighth invention includes a converter circuit that receives AC power and converts it into DC power, and an inverter that converts the DC power output from the converter circuit into predetermined AC power. In the power supply device having a circuit, the converter circuit is configured by connecting at least two switching circuits each including a rectifying element and a switching element in series, and the inverter circuit includes at least two switching circuits each including a rectifying element and a switching element. A smoothing capacitor is connected to the converter circuit, and at least two switching circuits each consisting of a rectifying element and a switching element are connected in series. circuit and the inverter circuit, one of the pair of AC power input parts is connected via a reactor between the switching circuits forming the converter circuit, and one of the pair of AC power output parts forms the inverter circuit. The other of the pair of AC power input parts and the other of the pair of AC power output parts are connected by a common line, and the other of the pair of AC power input parts and the other of the pair of AC power output parts are connected by a common line. , which is fully connected to the Yuki common line.

[Effect]

The constant voltage/constant frequency power supply device according to the first invention connects one of the pair of AC power input sections between the rectifying elements of the converter circuit, thereby rectifying the input AC power and converting it into a DC voltage. Ru.

This DC voltage is smoothed by a smoothing capacitor connected in parallel to the converter circuit.

A changeover switch unit connected in parallel to the converter circuit and inverter circuit combines the positive and negative input voltages and outputs O.
N, OFFI.

The DC voltage converted by the converter circuit is converted into a predetermined AC voltage by the inverter circuit.

This conversion is performed by switching control of a switching circuit that constitutes the inverter circuit.

Here, one of the power input sections and one of the power output sections are directly connected.

Therefore, the above conversion is performed on this input/output common side, and the circuit has a half-bridge configuration, and the changeover switch portion constitutes a circuit short-circuited to the input/output common line IP side or N side.

In the constant voltage/constant frequency power supply devices according to the second and eighth inventions, one of the pair of AC power input sections is connected between the switching circuits of the converter circuit.

This rectifies the input AC power and converts it into DC voltage.

The pressure of C is smoothed by a smoothing capacitor connected in parallel to the converter circuit.

A changeover switch unit connected in parallel to the converter circuit and inverter circuit allows the O
N, do OF'F.

The DC voltage converted by the converter circuit is converted into a predetermined AC voltage by the inverter circuit.

This conversion is performed by switching control of a switching circuit that constitutes an inverter circuit.

Here, one of the power input parts and one of the power output parts are for this reason, so the above conversion is performed on this input/output common side, the circuit has a half bridge configuration, and the changeover switch part connects this input/output common line. Configure a circuit that shorts to the P side or N side.

[Example of invention]

A constant voltage/constant frequency power supply device, which is a first embodiment of the present invention, will be explained based on FIG.

In the figure, (A) is a converter circuit, which is formed by connecting rectifying elements such as diodes (1) in series.

C) A smoothing circuit connected in parallel to the converter circuit (A). The smoothing circuit (B) consists of one smoothing capacitor (2
) is formed by.

G) is an inverter circuit connected to the smoothing circuit (B),
It consists of two series connected switching circuits (3).

This switching circuit (3) includes, for example, a transistor,
The loop is constituted by a switching element (8t) such as F'ET and a rectifying element (8d) such as a flywheel diode that connects the collector and emitter.

Φ) is a converter circuit (A) and an inverter circuit (C
) are connected in parallel to each other, and are configured by connecting t-2 switching circuits (6) in series, each consisting of a switching element (4) such as a transistor and a rectifying element (5) such as a diode.

One of the single-phase AC voltage power input sections (7) is connected to the two diodes (1) of the converter circuit (A) and the intermediate section.

Further, one of the power output sections (8) is connected to an inverter circuit (C
) is connected to the middle part of the two switching circuits (3).

The other power input section (7) and the other power output section (8) are connected by a single connection line (9).

This common line connecting line (9) is grounded and connected to the intermediate part of the changeover switch section (uniform switching circuit (6)).

Next, the operation of this first example will be explained.

A single-phase AC voltage is input from a power input section (7), and one of the power input sections (7) is connected to one of the power output sections (8) by a single connection line (9). Since this connecting line (9) is grounded, it is held at a predetermined potential.

The other end of the power input section (7) is connected to the intermediate portion of the two diodes (1) of the converter circuit (A) by a connecting line.

Since the diodes (1) are connected in series facing the same direction, the current flows only upward in the figure and is rectified.Then, the large lip μ obtained in this way is The included DC voltage is smoothed by a smoothing circuit (B), thereby obtaining a DC voltage with a rip μ of several % or less.

When the input voltage eo shown in FIG. 2 is positive, the positive half cycle of the output voltage Ivt-control.

When the input voltage eo is negative, the output voltage -(
10 negative half cycles/l/'i control.

The above-mentioned DC voltage is converted into AC power of a predetermined voltage and frequency by an inverter circuit (q).Switching in this inverter circuit (C) is performed by, for example, the following P
This is done by WM control. This PWM control C modulates and controls the width of the pulse applied to the base of the switching element (8t) of the inverter (C) to maintain a predetermined voltage,
Obtain AC power of frequency.

In the range of the voltage waveform (A) shown in FIG. 8(a), the current flows as shown in FIG. 8(b). Also, WIs diagram (
When the voltage waveform is in the range of ) shown in a), the current flows as shown in FIG. 8(d). Therefore, P shown in FIG.
A DC voltage of Jx2oo will be applied between N. This DC voltage x 200 = 282.8 V t-P
When the DC voltage is changed to AC by W M inverter control, when the DC voltage is in the range of voltage waveform (A) shown in Fig. 8(a), the voltage waveform shown in Fig. 8(C) and Fig. 8(a) is )
In the range of , the current flows as shown in FIG. 8(e).

And the output voltage will be 175v.

However, as a condition, the waveforms of the input voltage eo and the output voltage 100 may be different, but they must be in phase (the zero points of the voltages are the same).

The diagonally shaded portion on the positive side in FIG. 2 indicates that the switching element (4b) of the changeover switch section Q) in FIG. 1 is in a conducting state, and the switching element (8a) of the inverter circuit (C)
) shows the switching state, and the negative hatched part in FIG. 2 is the switching element (4a) of the changeover switch part p) in FIG. This shows a state in which the /g element (8b) is switching. Through such switching control, an output voltage having a waveform as shown by the curve QO in FIG. 2 can be obtained by passing the voltage through a filter circuit (not shown).

With the above configuration, the DC voltage VPN output from the smoothing circuit (B) becomes Ed.

Further, in this circuit, one of the input section and the output section is connected by one connection line. Therefore, there is no voltage change here, and noise can be prevented from being added to the output.
Further, since this connecting line is grounded, no step change in potential occurs between input and output, and noise generation is completely prevented.

In addition, as shown in Figure 6, the PWM control described in 1 allows the DC voltage to be reduced to V2 with the same human power voltage compared to the conventional one.
The same sinusoidal voltage fundamental wave can be generated, and by passing through a filter (not shown), a sinusoidal constant voltage/constant frequency output voltage can be obtained. Furthermore, the output voltage can be varied depending on the control command value.

Next, a constant voltage/constant frequency power supply device, which is a second embodiment of the present invention, will be explained using FIG.

In this example, the converter circuit (A) in FIG.
A converter circuit (k°) is used instead.

This converter circuit is a switching circuit (8T) consisting of a switching element (8T) such as a transistor or F'ET, and a rectifier (8C) such as a diode.
It is constructed by connecting two (b) in series.

One of the single-phase AC voltage power input sections (7) is connected to the intermediate section of the two switching circuits aυ of the converter circuit.

The configuration other than the above is the same as the embodiment of the first invention described above.

The second embodiment of the invention is constructed as described above, so that the circuit in this example has exactly the same construction as seen from both the input side and the output side. Furthermore, since the switching element has bidirectional current flow, it can function as either an inverter or a converter. Therefore, when the power source (self) is connected to the input side and the load (self) side is connected to the output side, power regeneration is possible in which power is sent from the load (to) side to the power source (home) side.

Next, a constant voltage/constant frequency power supply device, which is an eighth embodiment of the present invention, will be described.

In this dormitory example, one of the single-phase AC voltage power input sections (7) is connected to the intermediate part of the two switching circuits αη of the converter circuit C in FIG. 4, and a reactor}/ 1/αΦ, and the rest is the same as the second embodiment shown in FIG. 4.

The DC terminal voltage can be boosted by the reactor/L/α→ and the switching circuit Ql) of the converter circuit (F'), and in the embodiments of the first and second inventions, the output is the same as the input voltage. Although it was not possible to obtain a voltage, it is possible to obtain an output voltage equal to or higher than the input voltage by boosting the voltage to the required DC voltage.

According to the first, second, and eighth embodiments described above, an output voltage that is twice the voltage value of the conventional DC voltage circuit (in the case of only a single-phase half-bridge) can be obtained. That is, twice the output voltage can be obtained with the element breakdown voltage of one element being equivalent to that of the conventional circuit.

1.Converter circuit (F'), inverter circuit (C)
All the switching elements of the changeover switch section CD) are cut off, and the switching element 't-
By turning it ON and OFF, the input section can be directly connected to the output section. In other words, the input power can be output from the casing without being converted.

In the above-mentioned embodiment, a bibolar type transistor is shown as a transistor with a flywheel diode, but a MOSF'ET type transistor may be used, or an element that can operate in the same manner instead of these may be used.

Furthermore, since the switching element of the changeover switch part p) may be a commercial frequency switching element, there is no need to use a high-speed switching element.

〔Effect of the invention〕

As described above, according to the present invention, a smoothing capacitor is connected in parallel to the converter circuit, and at least two switching circuits #Ir are connected to the converter circuit and the inverter circuit.
The changeover switch parts connected in series are connected in parallel to a common line connecting the AC power input part and the AC power output part.
By connecting the intermediate parts of the two switching circuits of the changeover switch section, it is possible to obtain an output voltage of 200V class with a 100V class element, for example, without using a high withstand voltage element. Since no distance is required, the device itself can be made compact and inexpensive, making it possible to obtain a highly reliable constant voltage/constant frequency power supply device with excellent safety.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the basic circuit of a constant voltage/constant frequency power supply device according to an embodiment of the present invention, FIG. 2 is a waveform diagram showing the output waveform of a final embodiment of the invention, and FIG. - Fig. 1 is a state explanatory diagram showing voltage and current states, Fig. 4 is a basic circuit diagram showing another embodiment of the present invention, and Fig. 5 is a conventional constant voltage/current diagram.
FIG. 6 is a circuit diagram showing the basic circuit of the constant frequency power supply device, FIG. 6 is a waveform diagram showing the output waveform of the conventional device, and FIG. 7 is a state explanatory diagram showing the voltage and current states of FIG. 5. In the figures, (A) and (F') are converter circuits, (2) are smoothing circuits, (C) are inverter circuits, (D) are changeover switch sections, (1) are diodes (rectifying elements), and (2) are smoothing circuits. capacitor, (3)α]) is the switching circuit, (8
t) (4) is a switching element, (8d) is a rectifier element,
(5) is a switching element, (6) is a switching circuit, (7) is a power input section, (8) is a power output section, (9) is a connection line (common line), and α→ is a reactor. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (3)

[Claims] (1) In a power supply device including a converter circuit that receives AC power and converts it into DC power, and an inverter circuit that converts the DC power output from the converter circuit into predetermined AC power, the converter circuit includes: The inverter circuit is configured by connecting at least two rectifying elements in series, the inverter circuit is configured by connecting at least two switching circuits each consisting of a rectifying element and a switching element in series, and a smoothing capacitor is connected to the converter circuit. , a changeover switch section formed by connecting at least two switching circuits including a rectifying element and a switching element in series is connected in parallel to the converter circuit and the inverter circuit, and one of the pair of AC power input sections constitutes the converter circuit. one of the pair of AC power output parts is connected between the switching circuits forming the inverter circuit, the other of the pair of AC power input parts and the other of the pair of AC power output parts A constant voltage/constant frequency power supply device, characterized in that the switching circuits constituting the changeover switch section are connected to each other by a common line, and the switching circuits constituting the changeover switch section are connected to the common line. (2) In a power supply device including a converter circuit that receives AC power and converts it into DC power, and an inverter circuit that converts the DC power output from the converter circuit into predetermined AC power, the converter circuit includes: The inverter circuit is constructed by connecting at least two switching circuits each including a rectifying element and a switching element in series; A smoothing capacitor is connected to the converter circuit and the inverter circuit, and a changeover switch section consisting of at least two switching circuits connected in series, each consisting of a rectifying element and a switching element, is connected in parallel to the converter circuit and the inverter circuit. One end is connected between the switching circuits forming the converter circuit, one of the pair of AC power output parts is connected between the switching circuits forming the inverter circuit, and the other of the pair of AC power input parts is connected to the other one of the pair of AC power input parts. Connect the other side of the AC power output section with a common line,
Furthermore, the constant voltage/constant frequency power supply device is characterized in that the switching circuits forming the changeover switch section are connected to the common line. (3) In a power supply device including a converter circuit that receives AC power and converts it into DC power, and an inverter circuit that converts the DC power output from the converter circuit into predetermined AC power, the converter circuit includes: The inverter circuit is constructed by connecting at least two switching circuits each including a rectifying element and a switching element in series; A smoothing capacitor is connected to the converter circuit, and a changeover switch section, which is formed by connecting at least two switching circuits each consisting of a rectifying element and a switching element in series, is connected in parallel to the converter circuit and the inverter circuit, and a pair of AC power inputs are provided. One of the sections is connected via a reactor between switching circuits forming the converter circuit, one of the pair of AC power output sections is connected between the switching circuits forming the inverter circuit, and one of the pair of AC power input sections is connected between the switching circuits forming the inverter circuit. and the other of the pair of alternating current power output sections are connected by a common line, and further, a switching circuit constituting the changeover switch section is connected to the common line. Frequency power supply.