JP3661388B2 - Inverter device - Google Patents

Description

ここで、Ｔ_S ：サンプリング周期、ｉ_P(K)：Ｋ（Ｋ＝１・２・・・Ｎ）回目のサンプル時の電流検出器２１の検出値である。従って計測期間Ｔ＝Ｔ_S ・Ｎの関係から、式（１）は式（２）に変形される。
【００１３】
【数２】
Ｉ_RMS ＝｛（１／Ｔ）（ｉ_P(1) ² ＋ｉ_P(2) ² ＋・・＋ｉ_P(N) ² ）｝^1/2 …（２）
同様に、サンプリング周期Ｔ_S 毎の制御回路１４ａにおける前述のパルス幅変調の際の信号波から、式（２）と同様の下記の演算式の演算により、出力電圧の実効値Ｖ_RMS を求める。
【００１４】
【数３】
Ｖ_RMS ＝｛（１／Ｔ）（ｖ_P(1) ² ＋ｖ_P(2) ² ＋・・＋ｖ_P(N) ² ）｝^1/2 …（３）
ここで、ｖ_P(K)：Ｋ（Ｋ＝１・２・・・Ｎ）回目のサンプル時の前記信号波の値である。
また出力電圧と出力電圧の位相差（φ）は、前記ｖ_P(K)の零点通過値から前記ｉ_P(K)の零点通過値までの時間差および操作パネル２３からの周波数の設定値に基づいて演算することができる。
【００１５】
上述のそれぞれの値からインバータ装置２０が出力する有効電力Ｐは、式（４）の演算により求められる。
【００１６】
【数４】
Ｐ＝３・Ｖ_RMS ・Ｉ_RMS ・ｃｏｓφ …（４）
すなわち、式（４）で演算された有効電力を計測期間Ｔが終了した後、この有効電力を電力演算回路２２から操作パネル２３へ送出し、操作パネル２３の表示素子に表示させる。
【００１７】
さらに電力量ＷＨの演算は、操作パネル２３から発せられた開始指令に基づいて、予め操作パネル２３の操作により設定された積算時間をＴ_WHとすると、Ｔ_WH＝Ｘ・Ｔの関係から、下記の演算式により求められる。
【００１８】
【数５】
ＷＨ＝Ｋ₀ （Ｐ₍₁₎ ＋Ｐ₍₂₎ ＋・・＋Ｐ_(X) ） …（５）
ここで、Ｋ₀ （＝Ｔ／１時間）は換算係数を示し、Ｐ_(M) ：Ｍ（Ｍ＝１・２・・・Ｘ）回目の式（４）に基づく有効電力である。
すなわち、式（５）で演算された電力量を積算時間Ｔ_WHが終了した後、この電力量を電力演算回路２２から操作パネル２３へ送出し、操作パネル２３の表示素子に表示させる。
【００１９】
なお、式（３）の出力電圧の実効値Ｖ_RMS の演算に代えて、出力電圧の実効値は制御回路１４ａにおける前述のパルス幅変調の際の信号波が正弦波の場合にはその最大振幅に基づく値とする方法、平滑用コンデンサ１２の両端電圧の検出値に基づく値とする方法、逆変換回路１３の出力電圧の検出値に基づく値とする方法、制御回路１４ａがベクトル演算を行っているときにはこの演算値に基づく値とする方法などを用いてもよい。
【００２０】
さらに上述の実施例の動作説明では、操作パネルの操作により、計測期間Ｔ，積算時間Ｔ_WHを設定したが、インバータ装置を運転中に、交流電動機と交流電動機を動力源とする機械設備の動作を目視して、該操作パネルの操作により開始指令と終了指令とを与える方法でもよい。
【００２１】
【発明の効果】
この発明によれば、インバータ装置自体に動作中の出力電力または電力量を演算，表示する機能を備えることにより、その測定作業が自動化される。その結果、機械設備の稼働中の電力または電力量が容易に把握できる。
【図面の簡単な説明】
【図１】この発明の実施例を示すインバータ装置の回路構成図
【図２】従来例を示すインバータ装置の回路構成図
【符号の説明】
１ 交流電源
２ 交流電動機
３ 機械設備
１０ インバータ装置
１１ 整流回路
１２ 平滑用コンデンサ
１３ 逆変換回路
１４，１４ａ 制御回路
１５ 操作パネル
２０ インバータ装置
２１ 電流検出器
２２ 電力演算回路
２３ 操作パネル[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a display function of electric power or electric energy output from an inverter device.
[0002]
[Prior art]
FIG. 2 is a circuit configuration diagram showing a conventional example of this type of inverter device.
In FIG. 2, 1 is an AC power source such as a commercial power source, 2 is an AC motor as a load, 3 is mechanical equipment such as an industrial machine using the AC motor 2 as a power source, and 10 is an inverter device.
[0003]
The inverter device 10 includes, for example, a rectifier circuit 11 formed by bridge-connecting a plurality of diodes, a smoothing capacitor 12 such as an electrolytic capacitor, an inverse conversion circuit 13 formed by bridge-connecting a plurality of semiconductor switches, A control circuit 14 for controlling the semiconductor switch constituting the inverse conversion circuit 13 to be turned on / off by pulse width modulation (PWM) so that an AC voltage having a desired frequency and voltage is generated at the output of the inverse conversion circuit 13; And a panel 15.
[0004]
The operation panel 15 shown in FIG. 2 has a function of performing operations such as operation and stop of the inverter device 10, setting of a frequency output from the inverter device 10, and display of an operation state of the inverter device 10. Yes.
The inverter device 10 shown in FIG. 2 is configured by a well-known technique, and detailed description of the operation is omitted. However, in recent years, in order to implement a part of the functions of the control circuit 14 and the operation panel 15, a micro A computer is used.
[0005]
[Problems to be solved by the invention]
During the operation of the mechanical equipment 3 via the AC motor 2 that is variable-speed driven by the conventional inverter device 10 shown in FIG. 2, the output power or the amount of power of the inverter device 10 often changes each time. For example, when a power-saving plan for the entire factory is formulated based on these values, the voltmeter, ammeter, wattmeter, integrated wattmeter, etc. Was measured between the output of the inverter device 10 and the AC motor 2 for measurement.
[0006]
However, since the output voltage of the inverter device 10 is generally a variable frequency and variable voltage, the above-mentioned instrument requires a relatively expensive instrument that satisfies this characteristic, and this measurement operation is also a manual operation. .
An object of the present invention is to solve the above problems and to provide an inverter device having a function of calculating and displaying output power or electric energy during operation in the inverter device itself.
[0007]
[Means for Solving the Problems]
The present invention relates to an inverter device for converting a voltage of a DC power source into an AC voltage having a desired frequency and voltage by pulse width modulation and supplying power to a load, a current detector for detecting an output current of the inverter device, and the current detection A power calculation circuit that calculates and outputs one or both of the power and the amount of power output from the inverter device based on the detected value of the detector and the signal wave at the time of the pulse width modulation, and the power calculation And a display circuit for displaying the output value of the circuit.
[0008]
According to the present invention, the inverter device itself has the function of calculating and displaying the output power or the amount of power during operation, so that the measurement work is automated.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a circuit configuration diagram of an inverter device showing an embodiment of the present invention. Components having the same functions as those of the conventional circuit shown in FIG. 2 are denoted by the same reference numerals.
That is, the inverter device 20 shown in FIG. 1 has the same function as the rectifier circuit 11, the smoothing capacitor 12, the inverse conversion circuit 13, and the control circuit 14 shown in FIG. In addition to the control circuit 14a having a function of transmitting the current, a current detector 21, a power calculation circuit 22, and an operation panel 23 are provided.
[0010]
The operation panel 23 shown in FIG. 1 operates the inverter device 20 having the same function as the operation panel 15 shown in FIG. 2, such as operation and stop, setting of the frequency output from the inverter device 20, and the inverter device 20. In addition to the display of the operation state, the function for setting the measurement period for obtaining the output power of the inverter device 20, the function for setting the accumulated time for obtaining the electric energy, and the operation of the power calculation circuit 22 A function for sending a command to be started and a function for displaying the power or the amount of power obtained by the power calculation circuit 22 are additionally provided.
[0011]
The case where the power calculation circuit 22 included in the inverter device 20 calculates the power and the amount of power output from the device will be described below with reference to the case where the function of the power calculation circuit 22 is performed using a microcomputer.
Based on the start command issued from the operation panel 23, from the detection value (i) of the current detector 21 within the measurement period (T) set in advance by operation of the operation panel 23, the following equation is calculated. The effective value I _RMS of the output current is obtained.
[0012]
[Expression 1]

Here, T _{S is the} sampling period, i _{P (K)} is the detection value of the current detector 21 at the time of the Kth (K = 1 · 2... N) sampling. Thus the relationship between the measurement period T = T _S · N, the formula (1) is transformed into equation (2).
[0013]
[Expression 2]
I _RMS = {(1 / T) (i _{P (1)} ² + i _{P (2)} ² + ·· + i _{P (N)} ² )} ^1/2 (2)
Similarly, the effective value V _RMS of the output voltage is obtained from the signal wave at the time of the above-described pulse width modulation in the control circuit 14a for each sampling period T _S by the calculation of the following calculation expression similar to the expression (2).
[0014]
[Equation 3]
V _RMS = {(1 / T) (v _{P (1)} ² + v _{P (2)} ² + ·· + v _{P (N)} ² )} ^1/2 (3)
Here, v _{P (K)} : the value of the signal wave at the time of K (K = 1 · 2... N) sampling.
The phase difference (φ) between the output voltage and the output voltage is based on the time difference from the zero point passing value of v _{P (K) to} the zero point passing value of i _{P (K)} and the frequency set value from the operation panel 23. Can be calculated.
[0015]
The active power P output from the inverter device 20 from each of the above values is obtained by the calculation of Expression (4).
[0016]
[Expression 4]
P = 3 · V _RMS · I _RMS · cosφ (4)
That is, after the measurement period T ends, the effective power calculated by the equation (4) is sent from the power calculation circuit 22 to the operation panel 23 and displayed on the display element of the operation panel 23.
[0017]
Further, the calculation of the electric energy WH is based on the start command issued from the operation panel 23, and if the integrated time set in advance by the operation of the operation panel 23 is _TWH , from the relationship of _TWH = X · T, It is calculated by the following equation.
[0018]
[Equation 5]
WH = K ₀ (P ₍₁₎ + P ₍₂₎ +. + P _(X) ) (5)
Here, K ₀ (= T / 1 hour) indicates a conversion coefficient, and is P _(M) : M (M = 1 · 2... X) active power based on the expression (4).
That is, after the integration time _TWH has ended, the amount of power calculated by the equation (5) is sent from the power calculation circuit 22 to the operation panel 23 and displayed on the display element of the operation panel 23.
[0019]
Instead of calculating the effective value V _RMS of the output voltage in equation (3), the effective value of the output voltage is the maximum amplitude when the signal wave at the time of the pulse width modulation in the control circuit 14a is a sine wave. A method based on the detected value of the voltage across the smoothing capacitor 12, a method based on the detected value of the output voltage of the inverse conversion circuit 13, and the control circuit 14a performs vector calculation. A method based on this calculated value may be used.
[0020]
Furthermore, in the description of the operation of the above-described embodiment, the measurement period T and the integration time _TWH are set by operating the operation panel. However, the operation of the mechanical equipment using the AC motor and the AC motor as a power source during operation of the inverter device. It is also possible to give a start command and an end command by operating the operation panel.
[0021]
【The invention's effect】
According to the present invention, the inverter device itself has the function of calculating and displaying the output power or the amount of power during operation, so that the measurement work is automated. As a result, it is possible to easily grasp the power or power amount during operation of the mechanical equipment.
[Brief description of the drawings]
FIG. 1 is a circuit configuration diagram of an inverter device showing an embodiment of the present invention. FIG. 2 is a circuit configuration diagram of an inverter device showing a conventional example.
DESCRIPTION OF SYMBOLS 1 AC power supply 2 AC motor 3 Mechanical equipment 10 Inverter device 11 Rectifier circuit 12 Smoothing capacitor 13 Inverse conversion circuit 14, 14a Control circuit 15 Operation panel 20 Inverter device 21 Current detector 22 Power calculation circuit 23 Operation panel

Claims (1)

In an inverter device that converts the voltage of a DC power source into an AC voltage of a desired frequency and voltage by pulse width modulation and supplies power to a load.
A current detector for detecting an output current of the inverter device ;
A power calculation circuit that calculates and outputs one or both of the power and the amount of power output by the inverter device based on the detection value of the current detector and the signal wave at the time of the pulse width modulation ;
An inverter device comprising: a display circuit that displays an output value of the power calculation circuit.

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