JPS5963981A - Controller for inverter - Google Patents

Abstract

PURPOSE:To enable to flow a current in response to the variation in load torque by switching and connecting a plurality of batteries. CONSTITUTION:A value corresponding to the 50% of the output frequency of an inverter 5 is set to a setter 15, thereby comparing the output signal of an accelerator/decelerator 9 by a comparator 16 therewith to drive a relay 17. The relay 17 is energized when the output frequency becomes 50% or higher. Thus, batteries 1A, 1B are connected in series, and when less than 50%, the relay 17 is deenergized. The contacts 17A-17C of the relay 17 are operated to be connected in parallel or in series with each other.

Description

Detailed Description of the Invention (a) Description of the Technical Field The present invention is an energy conversion system that is equipped with an inverter device using a plurality of batteries as a power source and that operates a rotating load. The present invention relates to an improvement in a control device for an inverter device that can be used to control an inverter device.

(b) Description of the Prior Art Figure 1 shows the configuration of a conventional control device for an inverter device in an energy conversion system that is equipped with an inverter device using a battery as a power source and that rotates a traveling machine or the like via an AC electric motor. 1 is a battery, 2 is a reverse stagnation prevention diode, 3 is a reactor, 4 is a capacitor, 5 is an inverter device, 6 is a cross-hat motor, 7 is a running machine such as a bogie as a rotating load, s is a frequency Setting device, 9 is acceleration/deceleration circuit, 10 is ('pressure/frequency) converter, 11 is inverter output i,
, Ff pressure command device.

12 is a transformer for inverter output voltage feedback, 1
3 is a diode, 14 is a pulse width modulation circuit (hereinafter referred to as PWM).
(abbreviated as “circuit”).

FIG. 2 shows the relationship between the DC fAf voltage vno of the battery shown in FIG. 1, the AC output voltage vAo of the inverter device 5, and the output frequency. In the figure, the voltage VDO of the straight line 1 is constant regardless of the alternating output voltage and output frequency of the inverter device 5. In addition, the AC output of the inverter device 5'; qf
VAO and output frequency f are controlled so that the ratio (VAo/f) is constant.

FIG. 3 shows the characteristics of the rotating load 7 shown in FIG. 1, and generally shows the running load torque characteristics of mobile machines such as cranes and trolleys. From the figure, it can be seen that the torque at startup and at low rotation is about 200 degrees at high speed rotation. Moreover, FIG. 4 shows the relationship between the rotational load torque characteristic of FIG. 3 and the direct current IDO supplied from the 'α battery when driven by the inverter device of FIG. 1 and the output frequency f of the inverter device 5. It shows. As is clear from the figure, unless ionization of about 200% of that at high frequency is required at startup and at low frequency, it is not possible to drive the torque characteristic of the rotating load shown in FIG.

In this way, when driving a traveling load such as a truck with a conventional inverter device using a battery as a power source, a current of approximately 200 Hz of battery radio waves is required at startup and at low speeds during high speed operation. For this purpose, a battery capable of passing a current of 200 cm is required, and usually multiple batteries are used for this purpose.

(C) Purpose of the Invention The present invention has been made based on the above reasons, and provides for switching and connecting a plurality of batteries in an energy conversion system equipped with an inverter device that is driven by a plurality of electric layers and operates a rotating load. 'i according to the change in load torque
It is an object of the present invention to provide a control device for an inverter device that can flow u'IN at a low cost.

(d) Summary of the Invention The present invention provides a method for connecting batteries in parallel to a load that requires a large amount of torque at startup and at low speeds, increasing the load capacity and eliminating the need for torque at high speeds. By connecting batteries in series, the voltage applied to the AC motor can be reduced to
Second, the (voltage/frequency) ratio is controlled to be constant to effectively utilize battery power and to reduce the cost of the device.

(e) Structure and operation of the invention The present invention will be described below based on an embodiment shown in the drawings. FIG. 5 shows the main circuit of the inverter device of the present invention, which is driven by two batteries, and the electric motor for driving a traveling load, and the control circuit of the inverter device. In the same figure, IA
,, IBLdu pond 6D, relay contacts 17A, 17B,
17C through anti-reverse diode 2. and is connected in parallel to a capacitor 4 and an inverter device 5 via a reactor 3.

The output of the inverter device 5 is connected to an AC motor 6,
The AC motor 6 drives a traveling machine 7 as a rotating load.

The voltage 9 frequency command given to the AC motor 6 is sent from the frequency setter 8 to the comparator 16 via the acceleration/deceleration circuit 9. (voltage/frequency) input to converter 10. Further, the output voltage of the inverter device 5 is determined by the output voltage feedback transformer 12. The signal is combined with the output signal of the acceleration/deceleration circuit 9 via the diode 13 and applied to the inverter output voltage command unit 11 .

The outputs of the (voltage/frequency) converter 10 and the inverter output voltage command unit 11 are input to the PWM circuit 14, and the outputs are input to the inverter device 5, which connects the inverter device so that three-phase AC power can be obtained. Control 5.

On the other hand, the output of the acceleration/deceleration circuit 9 is input to the comparator 16 as described above, and is compared with the output of the setting device 15 that sets a value corresponding to the output frequency of the inverter device 5. Depending on the result of this comparison, relay 17 is activated.

FIG. 6 shows the operation of the present invention. By setting σ1 corresponding to the output frequency 50 of the inverter device 5 in FIG. 5 in the setting device 15, the output signal of the acceleration/deceleration circuit 9 is compared. 16 and drives a relay 17. When the output frequency becomes 50 or more, the relay 17 is turned on. This connects batteries IA and IB in series, and
If it is less than %, the relay 17 is turned off. Contacts 17A, 17)) and 17C of the relay 17 are connected to the battery 1. A, 111 are connected in parallel or in series.

In FIG. 6, 'vnc indicates the output voltage of the battery IA, 113, and vAO indicates the relationship between the AC output voltage of the inverter device 5 and the output frequency f. The inverter output voltage command device 11. in figure P05 is attached to the pestle in which the ratio of the AC output voltage VAO and the output frequency ef is constant. It is controlled by the PWM circuit 14. In addition, as a circuit for reducing fluctuations in the variable output voltage VAO due to changes in the DC voltage VNO when the output frequency is around 50 inches, the output voltage feed para-multipurpose transformer 12 and the diode 13 are provided with a circuit for controlling the stain pressure feedback. This suppresses fluctuations in the output voltage.

FIG. 7 is a characteristic diagram when the load torque characteristic shown in FIG. 3 is driven by the configuration shown in FIG.
no1. It shows the relationship between ID, ox and the synthetic battery voltage 'flF IDO. The battery composite current when the AC output frequency is less than 50% is the IDO number current ID0I I ”D.
flows. Also, at frequencies above 50%, batteries IA and IB
are connected in series, so IDo=IDo□=IDOft
current flows, increasing battery capacity compared to conventional methods.

The case where a pulse width modulation inverter device is used as an inverter device to control a traveling machine as a rotating load has been described above, but the present invention is not limited to this, and the present invention is not limited to this. Any inverse converter that performs variable frequency control can be used, and any load can be used as long as the torque decreases in inverse proportion to the rotational speed.

(f) Overall Effect As is clear from the above description, according to the present invention, a control device for an inverter device can be provided.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a control device for a conventional inverter device using a battery as a power source, Fig. 2 is an explanatory diagram of the operation of Fig. 1, and Fig. 3 is a characteristic diagram of a traveling machine as a rotating load in Fig. 1. Fig. 4 is a characteristic diagram when the load torque characteristic shown in Fig. 3 is driven by the conventional method shown in Fig. 1, Fig. 5 is a configuration diagram showing an embodiment of the present invention, and Fig. 6 is the operation of Fig. 5. FIG. 7 is a characteristic diagram when the load torque characteristic of FIG. 3 is driven by the configuration of FIG. 5 of the present invention. 1... Battery 2... Backflow prevention diode 3... Reactor 4... Capacitor 5...
Inverter device 6... AC motor 7... Rotating load 8... Frequency setting device 9... Acceleration/deceleration circuit 10... (Voltage/Frequency) converter 11... Inverter output voltage command device 12. ...Output voltage feedback transformer 13...
Diode 14...PWM circuit 15...Setter 16...Comparator 17...Relay (7317) Attorney Noriyuki Chika (and 1 others)
name) Figure 3 f (6A) □ Figure 6 Figure 7/ ('/,)→

Claims (1)

[Claims] A plurality of batteries, an inverter device to which source power is supplied from the plurality of batteries, and this inverter device l'? In a control device for an inverter device in an energy conversion system comprising an AC motor that is supplied with alternating current power and drives a rotating load at a speed proportional to the frequency of the alternating current power, A frequency setter, a comparator, and a relay that connect the plurality of batteries in parallel when the frequency of the AC power is low, and connect the plurality of batteries in series when the frequency of the AC power is high. A control device for an inverter device comprising a circuit.