JPH04195U

JPH04195U -

Info

Publication number: JPH04195U
Application number: JP3776690U
Authority: JP
Priority date: 1990-04-09
Filing date: 1990-04-09
Publication date: 1992-01-06

Description

[Brief explanation of the drawing]

第１図〜第４図はこの考案の一実施例に係り、
第１図はインバータ制御回路の構成図、第２図は
Ｖ／Ｆパターンを示す図、第３図は低速域のトル
ク−モータ電流の関係を示す図、第４図はすべり
補正動作を示した説明図、第５図〜第９図は従来
のインバータ制御回路を説明するもので、第５図
はインバータ制御回路の構成図、第６図はデツド
タイムＴｄ期間中によつて出力電流の方向と出力
電圧の関係についての説明図、第７図はデツドタ
イムＴａによつて出力電圧に電圧指令との誤差が
発生する様子を示した図、第８図はＶ／Ｆパター
ンを示した図、第９図は低速域のトルク−モータ
電流の関係を示す図である。図について、１はインバータ装置、２は三相誘
導電動機、３は電流検出器、４は実効値換算器、
５は励磁電流分設定器、６は可変利得増幅器、７
は周波数設定器、８は周波数補正演算器、９はＰ
ＷＭ制御回路、１０はＴｄ補正回路である。なお
、図中、同一符号は同一、または相当部分を示す
。 Figures 1 to 4 relate to an embodiment of this invention,
Figure 1 shows the configuration of the inverter control circuit, Figure 2 shows the V/F pattern, Figure 3 shows the relationship between torque and motor current in the low speed range, and Figure 4 shows the slip correction operation. The explanatory diagrams, FIGS. 5 to 9, explain the conventional inverter control circuit. FIG. 5 is a configuration diagram of the inverter control circuit, and FIG. 6 shows the direction of the output current and the output during the dead time Td. An explanatory diagram of the relationship between voltages. Figure 7 is a diagram showing how an error with the voltage command occurs in the output voltage due to dead time Ta. Figure 8 is a diagram showing the V/F pattern. Figure 9 is a diagram showing the relationship between torque and motor current in a low speed range. Regarding the figure, 1 is an inverter device, 2 is a three-phase induction motor, 3 is a current detector, 4 is an effective value converter,
5 is an excitation current setting device, 6 is a variable gain amplifier, 7
is a frequency setter, 8 is a frequency correction calculator, 9 is P
WM control circuit, 10 is a Td correction circuit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims

[Scope of utility model registration request]

An inverter device that operates an induction motor at variable speed includes a current detector that detects a current value supplied to the induction motor, and an effective value conversion that converts the current value detected by the current detector into a signal value converted to an effective value. and outputting a frequency correction signal by amplifying the difference between the output signal of the effective value conversion means and a level corresponding to the excitation current of the induction motor, which is set from the outside, using a variable gain that can be set from the outside. variable gain amplification means for adding the frequency correction signal outputted from the variable gain amplification means and the frequency setting value for the inverter device to obtain a frequency command for the inverter device; An inverter control circuit equipped with a Td correction means that can correct adverse effects and a V/F pattern that prevents overexcitation during no-load conditions.