JPS631373A - Inverter device - Google Patents

Abstract

PURPOSE:To obtain an inverter output having less waveform distortion by comparing a feedback signal proportional to an AC voltage converted by an inverter with a reference sinusoidal signal, integrating a deviation output to control ON/OFF of a switching element. CONSTITUTION:Power from a battery 1 is supplied through an inverter 2 and a filter 3 to an AC load 4. The output voltage of the inverter 2 is detected by a voltage detector 5, applied through a voltage regulator 6 to a comparator 7, and compared with a reference sinusoidal signal from a sinusoidal wave oscillator 8. A deviation signal from the comparator 7 is integrated by an integrator 9, and applied through a hysteresis comparator 10 to a switching circuit 11. A driver 12 receives a control signal from the circuit 11, and supplies a drive signal to the inverter 2.

Description

DETAILED DESCRIPTION OF THE INVENTION (#. Field of Industrial Application) The present invention relates to an inverter device that converts DC power into AC power by controlling switching elements such as thyristors and transistors on and off.

(Prior art) An inverter device that converts DC output into AC power is used to control the drive of an AC motor, or to transfer power obtained from wind power generation or solar cells to a charging device in remote islands or remote areas. The charged DC power is then converted to a predetermined AC power as needed, and used to supplement power demand.

Such an inverter device obtains alternating current power from a direct current power source by connecting switching elements such as transistors and thyristors in a bridge manner and sequentially turning on and off opposing switching elements in time series.

This on-off control is performed by controlling the duration of the on or off time of the switching element based on the comparison result between the sine wave reference signal and the feedback signal of the inverter output. Therefore, conventionally, a pulse width modulation (PWM) circuit has been used to control the pulse width that defines the duration of operation of the switching element based on the comparison result.

(Problems to be Solved by the Invention) However, the pulse width modulation circuit for controlling the on-off operation time length of the switching element has a complicated circuit configuration, and as the number of parts increases, reliability and cost are reduced. But a problem arises.

Furthermore, conventional inverter devices still have problems in terms of high-speed switching operations.

The present invention has been made in view of the above, and provides an inverter device that can simplify the circuit configuration, reduce costs, improve reliability, and enable high-speed switching operation to obtain a waveform output with low distortion. It is something.

(Means for Solving the Problem) In order to solve the problem of navigation, the present invention provides an inverter device that converts DC power into AC power by on-off control of switching elements. a sine wave oscillator that generates a sine wave oscillator; a comparison circuit that compares a feedback signal proportional to the output voltage of the inverter device with the reference sine wave signal and outputs a deviation signal thereof; and an integrator circuit that integrates the deviation signal. The device is characterized by comprising a control circuit that performs on/off control of the switching element based on the output signal of the integrating circuit.

(Example) Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

? Diagram Jl shows one embodiment of the inverter device according to the present invention, and is a configuration diagram when DC power from a battery is converted into AC power and supplied to an AC load.

The battery 1 stores electric power obtained from wind power generation, solar cells, etc., and supplies DC power to an inverter 2 composed of switching elements such as transistors or thyristors. The inverter 2 converts the DC power supplied from the battery 1 into AC power by turning on/off switching elements as is well known.

On-off control of the inverter 2 is performed by a drive signal supplied to the base if the switching element is a transistor, or by a drive signal supplied to the gate if the switching element is a thyristor. The filter 3 is for improving the waveform of the AC power obtained by the inverter 2, and has a smoothing effect. The AC power smoothed in this way is supplied to an AC load 4 such as an AC motor.

On the other hand, after the output voltage of the AC power obtained by the inverter 2 is detected by the voltage detection W5 as a voltage control system for controlling the output voltage, a voltage signal of a predetermined level is sent to the voltage ml regulator 6. is adjusted and output as a feedback signal to one terminal of the comparator 7. A sine wave signal of a predetermined frequency is supplied from a sine wave oscillator 8 as a voltage command value to the ten terminals of the comparator 7, and a deviation signal between the two signals is input to an integrating circuit 9. The integration circuit 9 integrates the deviation output from the comparison circuit 7 and supplies the integrated output to the bisteresis comparator 10. The hysteresis converter 10 is an integrating circuit 9
A comparison output (polarity) is sent to the switching circuit 11 based on the integral output from the hysteresis comparator and a predetermined hysteresis comparator threshold. The switching circuit 1 l creates a signal for controlling the switching elements constituting the inverter 2 on and off based on the output of the bisteresis converter 10 and outputs it to the drive circuit 12 . The drive circuit 12 receives the control signal supplied from the switching circuit 11 and supplies the inverter 2 with a base or gate drive signal for sequentially controlling and operating corresponding predetermined elements of the switching elements constituting the inverter 2,
Controls the inverter output voltage to follow the voltage command value. Although the circuit shown in FIG. 1 is intended for a single-phase inverter, it goes without saying that the invention can be similarly applied to a multi-phase inverter.

FIG. 2 shows a configuration for explaining the function of the circuit shown in FIG. 1, in which the output from the sine wave oscillator 8 is
L), and the output of the bisteresis converter 10 is eo
Let ut(t).

When the functional configuration of the present invention shown in FIG. 2 is rewritten into blocks in the S@ area, it is shown as shown in FIG. 3.

That is, the integrating circuit 9 is represented by a transfer function 1/ST, the hysteresis comparator 10 is represented by a transfer function K (K→ω), and the voltage regulator 6 is represented by a transfer function G.

When Figure 3 is written as a mathematical formula, it becomes, and when this is further rearranged, κ → ■゜ Therefore, it can be seen that if the circuit according to the present invention is adopted, an inverter output with a voltage waveform having the same phase as the human input signal can be obtained. Since the inverter output is not a rectangular wave but has a waveform more similar to a sine wave, the waveform obtained by the inverter device is a waveform in which harmonic components are suppressed.

(Effects of the Invention) As described above, the present invention includes a sine wave oscillator that generates a reference sine wave signal and a comparison circuit that compares a feedback signal proportional to an AC voltage converted by an inverter and outputs the deviation thereof. Equipped with an integrator circuit that integrates the deviation output and a control circuit that controls on/off of switching elements based on the output of the integrator circuit, it is possible to easily obtain an inverter output with little waveform distortion according to the reference sine wave signal. can. Furthermore, the configuration is extremely simple, and therefore an inexpensive and highly reliable device can be provided. Moreover, noise can be reduced by high frequency switching.

[Brief explanation of drawings]

ml is a block diagram showing an embodiment of an inverter device according to the present invention, FIG. 2 is a functional block diagram of the present invention, and FIG. 3 is a block diagram of the S@ area thereof. 1... Battery 2... Inverter 3... Filter 4... AC load 5... Voltage detector 6... Voltage regulator 7... Comparator 8... Sine wave oscillator 9...・Integrator circuit 10...Bisteresis converter 11...Switching circuit 12...Driver circuit

Claims (1)

[Claims] An inverter device that converts DC power into AC power by on-off control of switching elements, comprising: a sine wave oscillator that generates a control reference sine wave signal; a feedback signal proportional to the output voltage of the inverter device; and the reference sine wave signal. an inverter device comprising: a comparison circuit that compares and outputs a deviation signal; an integration circuit that integrates the deviation signal; and a control circuit that controls on/off of the switching element based on the output signal of the integration circuit. .