JPH0475485A - Power converting system - Google Patents

Abstract

PURPOSE:To effectively use energy by connecting a power storage device having a power. storage element and a power converter to a DC intermediate part of a converter and an inverter. CONSTITUTION:A power converter 52 is normally set to a standby state. If an AC power source 1 is interrupted while a motor 6 is regenerated, the converter 52 is immediately started by a start command, set to a charging mode, and the regenerative energy is charged in a power storage element 51 from the motor 6. If the motor 6 is switched from a regenerating mode to a power drive motor during stopping of the power source 1, the converter 52 is switched from the charging mode to a discharging mode, and the energy stored in the element 51 is supplied to a load motor 6 through the converter 52 and an inverter 4. When the motor is stopped if the energy is charged to be stored in the element 51, the inverter 4 is stopped, a converter 3 is driven in a regenerative mode, the converter 52 is operated in the discharging mode, and the power source 1 is regenerated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a power conversion system for driving a motor.

(Prior Art) FIG. 2 is a block diagram showing an example of the configuration of a conventional power conversion system. In Fig. 2, 1 is an AC power supply, 2 is a transformer 53, which has the function of converting AC to DC and also regenerating the energy generated on the load side to the AC power supply 1, and 4 is a converter that converts DC to AC. 5 is a transformer; 6 is a motor whose speed is controlled by the inverter 4; 11 is a step-down chopper;
2 is a resistor serving as a load for the step-down chopper. FIG. 3 is a configuration diagram showing an example of a step-down chopper. In FIG. 3, 31 is a gate turn-off thyristor (hereinafter simply GTO).
), 32 is a control device that provides the GTO 31 with a gate signal for controlling on/off of the GTO, 33 is a diode, and 34 is a reactor.

Next, the operation of the conventional power conversion system will be explained using FIGS. 2 and 3. In the power running mode of the motor 6, the energy of the AC power supply 1 is converted to DC by the converter 3, and the DC is converted to AC by the inverter 4, and the energy of the AC power supply 1 is converted to AC by the inverter 4.
supplied to

In the regeneration mode of the motor 6 when the AC power supply 1 is normal, the step-down chopper 11 is stopped, and the regenerative energy from the motor 6 is regenerated to the AC power supply 1 via the inverter 4 and the converter 3. If the AC power supply 1 has a power outage during the regeneration operation, the step-down chopper 11 is operated, and the GT 31 of the step-down chopper 11 is controlled on/off so that the DC intermediate circuit voltage between the converter 3 and the inverter 4 is constant.

(Problems to be Solved by the Invention) The motor drive power conversion system including the step-down chopper 11 and the resistor 12 in the DC intermediate section has the following problems.

In the conventional system, the regenerated energy from the motor 6 is consumed by the resistor 12, so the regenerated energy cannot be used effectively. This problem becomes more pronounced as the system becomes larger; for example, in a 50MVA class system, regenerative energy of about IOMVA may be generated, and the loss in the resistor 12 is enormous.

Furthermore, in the conventional system, if the AC power supply 1 loses power while the motor 6 is in regenerative operation, the converter 3 must be stopped immediately. In this case, there is a disadvantage that the motor cannot be operated in power because the AC power supply 1 is out of power.

The present invention has been made to solve such problems, and an object of the present invention is to provide a power conversion system that can store regenerative energy from a load-side motor or energy from an AC power source and reuse it when necessary.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention is characterized in that a power storage device including a power storage element and a power conversion device is connected to a DC intermediate portion between a converter and an inverter. It is.

(Function) By providing the above-mentioned means, the regenerated energy from the motor can be stored in the power storage device through the inverter when the AC power supply is cut off, or the energy of the AC power supply can be stored in the power storage device through the converter when the motor is stopped. It is also possible to supply the energy of the power storage device to the motor via the inverter when the motor is in power running mode, and to regenerate the energy of the power storage device to the AC power source via the converter when the motor is stopped.

(Example) An example of the present invention will be described below with reference to FIG. In FIG. 1, the names and operating functions of the parts designated by the same reference numerals as in FIG. 2 are the same, and their explanations will be omitted.

In FIG. 1, 51 is a power storage element such as a battery;
52 is a power conversion device such as a known current reversible chopper that can control charging current and discharging current for the power storage element 51.

In FIG. 1, it is assumed that a predetermined initial charging of the power storage element is performed by the power conversion device 52 via the converter 3. Normally, the power converter 52 is kept in a standby state, and if the AC power supply 1 loses power while the motor 6 is in a regenerative operation, the power converter 52 is immediately started by a start command (not shown) and the power converter 52 is set to charging mode operation. The power storage element 52 is charged with the regenerated energy. When the motor 6 switches from the regeneration mode to the power running mode while the AC power supply 1 is out of power, the power converter 52 is switched from the charging mode operation to the discharging mode operation, and the energy stored in the power storage element 51 is converted into electric power. Device! 52
and is supplied to the load motor 6 via the inverter 4.

When energy is charged and stored in the power storage element 51 and the motor is stopped, the inverter 4 is stopped, the converter 3 is operated in the regeneration mode, and the power conversion bag W152 is operated in the discharge mode, and the energy stored in the power storage element 51 is stored. is regenerated to AC power supply 1. In addition, if the energy in the power storage element 51 is not sufficiently stored, the converter 3 is operated in power running mode when the motor is stopped, and the power converter 52
is operated in charging mode, and the energy of the AC power source is stored in the power storage device 51 up to a predetermined amount.

In the above description of the present invention, when the AC power supply is normal, the load side also regenerates all the regenerative energy from the motor to the AC power supply.5 However, it is also possible to store part or all of this in the power storage device 51. .

〔Effect of the invention〕

According to the present invention, the regenerated energy from the motor on the load side is stored in the power storage device without wasting it in the resistance, so it is possible to use energy effectively and greatly contribute to energy consumption. Furthermore, even during a power outage of the AC power source, energy can be supplied from the power storage device to the load-side motor via the inverter to enable power running of the motor, increasing the operating efficiency of the system.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a block diagram showing an example of the configuration of a conventional power conversion system, and FIG. 3 is a block diagram showing an example of a step-down power conversion system. 1... AC power supply, 3... converter, 5. ...Transformer, 51...Power storage element, 60...Power storage device. 2...Transformer, 4...Inverter, 6...Motor, 52...Power conversion device, Agent Patent attorney Noriyuki ChikaFigure 2Figure 1Figure 3

Claims (1)

[Claims] An AC power supply, a converter having a function of converting AC to DC and regenerating energy generated on the load side to the AC power supply, an inverter connected to the output side of the converter and converting DC to AC, and the inverter. In the system, a power storage device including a power storage element and a power conversion device is connected to a DC intermediate portion between the converter and the inverter, and when the AC power supply is interrupted, the power is The regenerated energy from the motor, or when the motor is stopped, the energy of the AC power supply is stored in the power storage device via the converter, and when the motor is running, the energy of the power storage device is stored in the inverter. A power conversion system characterized in that the power is supplied to the motor through the converter, and when the motor is stopped, the energy in the power storage device can be regenerated into an alternating current power source through the converter.