JPS6082096A - Controller of plural inverters - Google Patents

Abstract

PURPOSE:To reduce the capacity of a regenerative power inverter as small as possible by generally controlling an operation pattern and maintaining the total regenerative power constant. CONSTITUTION:Instantaneous power is calculated by a multiplier 10 from the voltage and current detected by a voltage detector 8 and a current detector 9. An adder 11 adds the total sum of the instantaneous powers of n inverters. A comparator 12 compares the all regenerative power outputted from the adder 11 with the set capacity of a capacity reference unit 13 of regenerative power inverter, and limits the falling speed of the speed reference unit 14 of respective VVVF device 6. Thus, when the n motors are all regenratively braked, the operating pattern of an IM 7 can be controlled so that the maximum value of the regenerative power from the IM 7 becomes constant. Thus, the capacity of the regenerative power inverter (not shown) can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an inverter control device, and more particularly, to an improvement of a control device for a plurality of inverters in which the total regenerated power is constant.

[Technical background of the invention and its problems]

Figure 1 shows the main circuit for controlling a drive motor by an inverter using a conventional DC common component.

This will be explained below. In the figure, 1 is a contactor, 2 is an AC reactor, and 3 is a rectifier (hereinafter abbreviated as R and F).几F3 is a three-phase bunryu electric wire (not shown)
The capacitor 5C rectifies the current and photoelectrically converts it into a current voltage.

Is this direct current? The W voltage is converted into an alternating current voltage by a variable voltage/variable frequency converter 6 (hereinafter abbreviated as vvvp) to drive an alternating current electric lamp 7 (hereinafter abbreviated as IM). When IM7 is powered, power is supplied from the AC power source 1→2→3→5→6
→7, and power is supplied to the load at IM7.

Also, when IM7 is powered by a load, IM7
7+2, it is converted into electric power, passes through the VVVF 6, charges the capacitor 5 as a DC voltage, and the DC voltage increases. When this DC voltage exceeds a certain set value, the regeneration inverter 4 (hereinafter abbreviated as PB-I) is operated and controlled to regenerate the DC power into AC power. From the above, the energy given by the power is 7-6-5→4+2→l
It can be regenerated into AC power as in

Conventionally, the capacity of the aF3 has been selected to satisfy the required amount of VVVF 6 when running (vvvp 6 for all units).

In addition, the capacity of P'B-I4 was selected so that the maximum total regenerated energy of IM7 could be regenerated into the AC power supply.

However, in order to shape the current waveform regenerated into AC,
In order to configure PB-I4 using the PWM method, although it is advantageous to use transistors, etc., there are limitations in their capacity and speed, so the maximum capacity of IM7, which is the capacity of PB-I4, is limited. It is impossible to make a selection based on total regenerative energy, and it is economical to make the PB-I4 space small.

〔the purpose〕

The present invention has been made in view of the above reasons, and provides an economical control device for a plurality of inverters, which suppresses the capacity of a regenerative inverter as much as possible and makes the total regenerative power constant. The above object is achieved by providing a circuit that detects and controls the amount of regenerated power of a variable voltage/variable frequency converter for driving an AC motor, thereby reducing the capacity of the inverter.

[Example of inventive ability ζ]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 6. The main circuit configuration of the present invention is shown in FIG.

The configuration is the same as the conventional configuration.

FIG. 2 shows a typical motor operating pattern. A plurality of I M 7 are at time t in FIG. When the IMs 7 start to start up all at once, each IM 7 consumes power as shown in FIG. Assuming that the total number of IM7s is n and the maximum power required for each motor is Pim, the maximum power that must be supplied to the AC power supply IM7 is:

Since this power must be supplied by RF'3, the capacity of RF3 is determined by Equation 11.

With this capacity, it is possible to accelerate all n IM7s simultaneously. In this case, the capacity of RF3 is currently VVV
Since it is possible to manufacture something much larger than the F6, it is highly feasible.

Next, consider the case where all n electric motors are put into regenerative braking operation at time t2 in FIG.

The maximum power regeneration amount prw after time t2 is prw=
Σ Pin −(2) i==1. In this case, the capacity of PB-I4 is the number of IM7s n
If the size becomes too large, production becomes impossible or uneconomical.

Therefore, in the present invention, the capacity of FB-I4 is set as PR, and the operation pattern of IM7 is generated as shown in Fig. 4 so that regeneration is possible in view of this, and the total regenerative power from IM7 is The maximum value is controlled to be constant as shown in FIG.

FIG. 6 shows the specific circuit configuration of this control method.
9 is a voltage detection element, 9 is a current detection element, and 10 is a multiplier that calculates instantaneous power from the voltage and current detected by the voltage detection element 8 and current detection element 9. 11 is an adder for summing the instantaneous power of n units, and 12 is a speed reference device for each vvvp device 6, which compares the total regenerated power outputted from the adder 11 and the capacity of the PB-I4 with the set capacity of the reference device 13. (or V/F reference device) 14 is a comparator that limits the descending speed.

However, instead of this comparator, the capacity reference device 13 of the VVVF 6 may be provided with a function generator for generating a speed reference as shown in FIG. Alternatively, by setting the order of limiting as shown in Fig. 6, the regenerative power can be adjusted to PB-I4.
An economical system can be realized by keeping the capacity below .

With the above configuration, the operation pattern of the IM7 must be changed from FIG. 2 to FIG. 4. However, as shown in Figures 3 and 5, the time when power regeneration is large is small compared to other times, so in applications where this initial deceleration characteristic is not a concern, the capacity of PB-I4 can be reduced. There are significant benefits.

Also, according to a method such as ranking Sa patterns for n IM7s (according to 2), those with higher rankings will be like the driving patterns in Figure 2.

The other driving patterns are as shown in Figure 3, and even though the capacity of PB-I4 has been reduced, there will also be an IM7 that can operate quite close to the conventional driving pattern. It also provides economic benefits when controlling flocks.

〔Effect of the invention〕

In this way, according to the present invention, it is possible to provide an effective control device for a plurality of inverters in which the total regenerated power is constant by comprehensively controlling the operation pattern.

[Brief explanation of drawings]

Figure 1 is the main circuit diagram of multiple inverters, Figure 2 is a diagram showing the motor operation pattern, Figure 3 is a diagram showing the motor power in pattern C22 of Figure 2, and Figure 4 is the motor operation pattern. FIG. 5 is a diagram showing the motor power in the pattern of FIG. 4, and FIG. 6 is a block diagram showing an embodiment of the present invention. Engineering: Contactor, 2: AC reactor. 3... Rectifier, 4... Inverter for power regeneration, 5...
... Capacitor, 6... Town variable frequency town variable voltage converter, 7... AC motor, 8... Voltage detection element, 9...
...Voltage detection element. (7317) generation (four speakers: Kensuke Norichika (and one other person) Figure 1 1 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] A rectifier that converts three-phase alternating current power into direct current, a capacitor that charges the rectified direct current, a plurality of inverting devices that convert the direct current to alternating current via the capacitors, and a drive device driven by these inverting devices. A power conversion device comprising a plurality of AC electric camellias, and an inverse converter that regenerates the DC into a three-phase AC power supply, comprising: a voltage detector that detects the voltage supplied to each of the motors; A current detector for detecting, multipliers for multiplying the detected voltage and current, and an adder for adding the outputs of the multipliers, and control is performed so that the total regenerative power is constant. Multiple inverters with special mission! 1. Control device.