JPS5961478A - Inverter device - Google Patents

Abstract

PURPOSE:To simplify the configuration of a reactive current control circuit by operating a current transformer used for a circuit for detecting the output current also as a current transformer used for the bias circuit of an oscillating transistor of an inverter in combination. CONSTITUTION:Two secondary coils are provided in a current transformer provided between an inverter 1 and a load circuit. One of the coils is used for a biasing an oscillating transformer of an inverter 1, and the other is used for detecting the number of load circuits. The variation in the inductance of the output transformer is reduced by flowing a current to the inductance CH1 connected to the output terminal of the inverter 1 when the load circuits are less, thereby suppressing the oscillating frequency to a constant width.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an inverter device that supplies AC power to a load including a reactance element.

(Background Art) FIG. 1 shows a conventional example, in which numeral 1 converts DC power into AC power. For example, an inverter such as a pushinable inverter as shown in FIG. 2 has an electrical oscillation system and performs self-oscillation by positive feedback of an output voltage to the oscillation system. A plurality of load circuits each consisting of a series circuit of an inductance 2 and a load 3 are connected to the output end of the inverter 1 in parallel. In addition, a current transformer CTl is installed between the inverter 1 and the load circuit in order to provide an appropriate base bias voltage to the transistors rrl and 'I'r2 in the inverter 1 in response to changes in the output current due to changes in the number of load circuits. A DC voltage is generated according to the output current. The transformer i"2 provided at the output end is a feedback winding, and as mentioned above, the output voltage is positively fed back to the inverter 1 to cause self-oscillation, and in this inverter 1, the output voltage Tl changes due to changes in the output current. In other words, as the output current decreases, the inductance increases, and as the output current increases, the inductance decreases.In addition, the oscillation period of inverter 1 is determined by the oscillation period of output voltage T and capacitor C1. Therefore, the oscillation period changes as the output current changes, and the oscillation period increases as the output current changes.

As mentioned above, there is a load 3 connected in series with the inductance 2 at the output end, and as the number of load circuits increases, the output current becomes thicker (
Then, the oscillation period becomes shorter and the impedance of the inductance 2゛ becomes thicker (therefore, the load current becomes smaller. Conversely, when the number of load circuits decreases, the output current decreases and the load current becomes larger).

In response to changes in the load current due to changes in the load circuit, by flowing current through the inductance C111 connected to the output terminal of the inverter 1 when the load circuit is small, the change in inductance of the output transformer T1 is reduced, and the oscillation frequency is reduced. A method of keeping the load current constant is effective and can suppress load current fluctuations. Therefore, when the number of load circuits is small, a switch S that connects an inductance CH1 to the output terminal of the inverter 1, and a current transformer CT2 that detects the output current, determines the number of load circuits, and controls the switch S. The current control circuit 4 has, for example, the circuit configuration shown in FIG. ) When a DC current flows through B3, the Zener diode ZIJ is turned off, the transistor R3 is turned off, and the relay S is turned on.It is the same as that, and the same reference numerals are given to the same structure as the conventional example. omitted.

However, in the inverter device as described in 11J, two current transformers C'll and C-12 are required, which increases the number of parts and increases the cost.
The drawback is that the power loss due to the current transformer is also large.

(Object of the Invention) The present invention was made in view of the above-mentioned drawbacks, and its purpose is to reduce costs by simplifying the configuration of a reactive current control circuit provided at the output end of an inverter, and to reduce power consumption. The goal is to reduce losses and improve efficiency.

(Disclosure of the Invention) The present invention will be described below based on an embodiment shown in FIG. The difference from the first conventional example is that two secondary windings are provided in the current transformer C1' provided between the inverter l and the load circuit, and the -100 (terminal E) is set. Since this is the same as the conventional example, the explanation will be omitted.

(Effects of the Invention) As described above, the present invention simplified the configuration of the reactive current control circuit provided at the output end of the inverter, thereby reducing costs and providing an inverter device with reduced power loss.

[Brief explanation of drawings]

1 to 4 are circuit diagrams showing a conventional example, and FIG. 5 is a circuit diagram showing an embodiment of the invention. Patent applicant Matsushita Electric Works Co., Ltd. Patent attorney Toshimaru Takemoto (and 2 others) Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] α) It has an electric FrJ vibration system, and is equipped with an inverter that converts DC power into AC power by positive feedback of the output voltage to the vibration system and self-excited oscillation, and an inductance and a switch are installed at the output end of the inverter. An inverter device characterized in that a current transformer used in the circuit is used as a bias circuit for an Inno'-Tano oscillation transistor and also serves as a current transformer.