JPH08202461A - Biased magnetization preventing circuit of output transformer of parallel inverter - Google Patents

Abstract

PURPOSE: To prevent the biased magnetization of the output transformer of a parallel inverter constituted by connecting the secondary side of the output transformer in series. CONSTITUTION: Inverter units 2-1 and 2-2 are provided with output current detectors 2-1D and 2-2D which detect output currents respectively, and control circuits 4-1 and 4-2 of the inverter units 2-1 and 2-2 are provided with integrators 41-1 and 41-2 which output DC component corresponding signals corresponding to DC components of the output currents, comparators 42-1 and 42-2 which output inverter control signals for eliminating the DC component corresponding signals, and PWM pulse generating circuits 43-1 and 43-2 which obtain pulse- width modulated signals from the inverter control signals. Therefore, since the respective inverter units are controlled with the pulse-width modulated signals that can cancel the DC components of the output currents, biased magnetization due to a difference in characteristics of a switching element can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-bias circuit for an output transformer of a parallel inverter, and more specifically, it provides an output transformer on each output side of a plurality of inverter units. The present invention relates to a bias magnetism prevention circuit for an output transformer of a parallel inverter that obtains an AC output from between terminals in which the secondary sides of the transformers are connected in series.

[0002]

2. Description of the Related Art In an inverter that converts DC power into AC power, in order to insulate between a DC input side and an AC output side,
There is one in which an output transformer is interposed between the inverter output and the AC output.

In order to increase the output capacity of the above-mentioned inverter, a plurality of inverter units are connected in parallel, and the secondary side of the output transformer provided on each output side is connected in series. An AC output is obtained from the terminals connected in series.

A conventional example of such a parallel inverter is shown in FIG.
This will be described below. In FIG. 2, 1 is a DC power source, 2-
Reference numerals 1 and 2 are inverter units for converting DC power from this DC power supply into AC power, and conversion units 2-1A and 2-2A having switching elements bridge-connected,
DC filters 2-1B and 2-connected to the input side
2B and an AC filter 2-1 connected to the output side thereof
C and 2-2C, and an output current detector 2-2D is provided on the output side of one conversion unit 2-2A. 3-
Reference numerals 1 and 3-2 are output transformers provided on the output sides of the inverter units 2-1 and 2-2, and their secondary sides are connected in series, and an AC output is obtained from the terminals connected in series. I am trying.

In the above-mentioned parallel inverter, the function of preventing the demagnetization of the output transformers 3-1 and 3-2 provided in the respective inverter units 2-1 and 2-2 and the conversion section 2-
A control circuit 4 having a function of obtaining a control signal for the switching elements in 1A and 2-2A is provided.

That is, the control circuit 4 inputs the output current corresponding value detected by the output current detector 2-2D and outputs a DC component corresponding signal corresponding to the DC component, and an integrator 41, From a comparator 42 that inputs a DC component corresponding signal and a reference control signal from the reference control signal generating circuit 5 and outputs an inverter control signal that makes the DC component corresponding signal zero, the inverter control signal and the carrier signal A PWM pulse generating circuit 43 for obtaining a pulse width modulation signal is provided, and a control signal for a switching element capable of preventing biased magnetization of the output transformers 3-1 and 3-2 by the action of the comparator 42 can be obtained. .

Since the output current corresponding value detected by the output current detector 2-2D is a sine wave containing the ripple of the frequency of the carrier wave for obtaining the PWM pulse, the output current corresponding value corresponds to the cycle of this sine wave. By setting the time constant of the integrator 41 sufficiently large, the integrator 41 can output a DC component corresponding signal corresponding to the DC component in the output current.

[0008]

In the above-mentioned conventional bias magnetic prevention circuit for the output transformer of the parallel inverter, the control circuit 4 is used.
Although it is possible to prevent the magnetic bias due to the fluctuation of the zero potential of the analog arithmetic element used in the above, it is possible to prevent the magnetic bias due to the ON resistance of the switching elements constituting each inverter unit or the difference in the switching speed. There was a problem that I could not.

[0009]

In order to solve the above problems, the present invention relates to a DC power supply, and a plurality of inverter units for converting DC power from the DC power supply into AC power.
A control circuit that obtains a control signal of a switching element that constitutes each of the inverter units, and an output transformer that is provided on the output side of each of the inverter units and has secondary sides thereof connected in series, are connected in series. In a bias magnetism prevention circuit for an output transformer of a parallel inverter configured to obtain an AC output from between terminals of the transformer, an output current detector for detecting each output current is provided in each of the inverter units, and the control circuit is also provided. An integrator that inputs the output of the output current detector and outputs a DC component corresponding signal corresponding to the DC component of the output current, and the DC component corresponding signal and the reference control signal from the reference control signal generating circuit are input. And a comparator for outputting an inverter control signal to make the DC component corresponding signal zero, and a pulse width modulation signal from the inverter control signal and the carrier signal. A PWM pulse generating circuit for obtaining a formed, is characterized in that the pulse width modulated signal as a control signal of the switching element.

[0010]

According to the present invention, since the inverter control signal for making the DC component corresponding signal corresponding to the DC component of the output current of each inverter unit zero is output, it is provided in each inverter unit. The voltage-time products of the output transformers can be equalized.

[0011]

EXAMPLES The present invention will be described below with reference to examples.

FIG. 1 is a circuit diagram of an anti-bias circuit of an output transformer of a parallel inverter according to the present invention. Parts having the same functions as those in FIG. 2 are designated by the same reference numerals, and the following description will be omitted.

A feature of the present invention is that the inverter unit 2-
An output current detector 2-1D that detects the output current of the conversion unit 2-1A in the inverter unit 2 is connected to the inverter unit 2-
An output current detector 2-2D for detecting the output current is provided on the output side of the conversion unit 2-2A in 2 and the conversion unit 2-
Control circuit 4 for obtaining control signal of 1A switching element
1 and a control circuit 4-2 that obtains a control signal for the switching element of the conversion unit 2-2A. The control circuit 4-1 corresponds to the output current detected by the output current detector 2-1D. The integrator 41-1 which inputs a value and outputs a direct current component corresponding signal corresponding to the direct current component, and the direct current component corresponding signal and the reference control signal from the reference control signal generating circuit 5 are input to input the direct current component. Comprising a comparator 42-1 that outputs an inverter control signal that makes the corresponding signal zero, and a PWM pulse generation circuit 43-1 that obtains a pulse width modulation signal from this inverter control signal and a carrier signal. 2 is an integrator 41-2 which inputs the output current corresponding value detected by the output current detector 2-2D and outputs a DC component corresponding signal corresponding to the DC component,
A comparator 42-2 which inputs the DC component corresponding signal and the reference control signal from the reference control signal generating circuit 5 and outputs an inverter control signal for making the DC component corresponding signal zero.
A PWM pulse generation circuit 43-2 for obtaining a pulse width modulation signal from the inverter control signal and the carrier signal, and the output transformer 3-by the action of the comparator 42-1.
1 is prevented and the output transformer 3-2 is prevented from being biased by the action of the comparator 42-2.

Each of the above-mentioned inverter units 2-1 and
2-2 is an output current detector 2-1 for detecting the output current
D and 2-2D are provided, and the output current corresponding values detected by the output current detectors 2-1D and 2-2D are input to the respective control circuits 4-1 and 4-2, and the DC corresponding to the DC component is input. Integrators 41-1 and 41-2 that output component-corresponding signals,
In the bias prevention circuit including the comparators 42-1 and 42-2 that output the inverter control signal that makes the DC component corresponding signal to zero, the output current detectors 2-1D and 2-2D detect the bias current. Since the output current corresponding value is a sine wave containing the ripple of the frequency of the carrier wave for obtaining the PWM pulse, the integrator 41-1,
By setting the time constant of 41-2 sufficiently large, it is possible to output a DC component corresponding signal corresponding to the DC component in the output current from the integrators 41-1 and 41-2.

[0015]

As described above, the present invention provides
An output current detector is provided in each inverter unit that constitutes a parallel inverter to detect the DC component of the output current,
Since a DC component corresponding signal corresponding to the DC component is output and an inverter control signal that makes the DC component corresponding signal zero is output, the ON resistance of the switching elements between the inverter units and the difference in the switching speed are different. It is also possible to prevent magnetic bias due to

[Brief description of drawings]

FIG. 1 is a circuit diagram of a bias prevention circuit for an output transformer of a parallel inverter of the present invention.

FIG. 2 is a circuit diagram of a conventional anti-bias circuit for an output transformer of a parallel inverter.

[Explanation of symbols]

 2-1 and 2-2 Inverter unit 2-1A and 2-2A Converter 2-1D and 2-2D Output current detector 3-1 and 3-2 Output transformer 4-1 and 4-2 Control circuit 41- 1, 41-2 Integrator 42-1 and 42-2 Comparator 43-1 and 43-2 PWM pulse generation circuit 5 Reference control signal generation circuit

Claims (1)

[Claims] 1. A DC power supply, and a plurality of inverter units for converting DC power from the DC power supply into AC power.
A control circuit that obtains a control signal of a switching element that constitutes each of the inverter units, and an output transformer that is provided on the output side of each of the inverter units and has secondary sides thereof connected in series, are connected in series. In an anti-bias circuit of an output transformer of a parallel inverter that obtains an AC output from between the terminals of the output transformer, each of the inverter units is provided with an output current detector for detecting each output current, and An integrator that inputs the output of the output current detector to the control circuit and outputs a DC component corresponding signal corresponding to the DC component of the output current; a DC component corresponding signal and a reference control signal from the reference control signal generating circuit; And a comparator for outputting an inverter control signal for making the DC component corresponding signal zero, and a pulse width from the inverter control signal and the carrier signal. PWM pulse generation provided a circuit, wherein the pulse width biased magnetization prevention circuit of the output transformer of the parallel inverter is characterized in that as a control signal of the modulated signal the switching element to obtain a tone signal.