JP2006238520A - Load drive unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a load drive unit that can properly control electrical energy accumulated in a capacitor according to the operation condition of a load. <P>SOLUTION: The load drive unit comprise: an AC/DC converter that accumulates power imparted from an external power supply in the capacitor, and collects the power accumulated in the capacitor to the external power supply; and an inverter that drives the load by using the power accumulated in the capacitor, and accumulates regenerative power obtained from the load. A controller for controlling the operation of the AC/DC converter determines a set voltage that controls a charging amount of the capacitor by predicting an amount of the power-factor drive power of the load or an amount of regenerative power form the load in accordance with the state quantity of the load. When a voltage of the capacitor is lower than the set voltage, a power supply operation from the external power supply is conducted, and when the voltage of the capacitor is higher than the set voltage, a power regeneration operation to the external power supply is conducted. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a load driving device suitable for driving an elevator such as a crane.

  Load drive devices that drive cranes and other elevators generally convert a DC / AC converter that converts AC power into DC power, and the DC power output from this DC / AC converter is converted to AC with controlled voltage and frequency. And an inverter for driving the electric motor. Further, the DC power output from the DC / AC converter is stored in a capacitor (capacitor), and the inverter is power-driven using the power stored in the capacitor, and the regenerative power obtained via the motor is supplied to the capacitor. It is also proposed to accumulate the data in the inverter and reuse it for driving the inverter (see, for example, Patent Document 1).

Recently, attention has been focused on a small-sized and large-capacity electric double layer capacitor, and it is considered to use an electric double layer capacitor as a power storage capacitor in the load driving device described above.
Japanese Patent Laid-Open No. 10-267076

  By the way, driving the electric motor in the elevator such as the crane described above requires a large amount of electric power (powering energy), and the regenerative electric power (regenerative energy) obtained from the electric motor is large. Therefore, how to efficiently input / output the electric power (power energy) to / from the electric double layer capacitor becomes a problem. Moreover, in order to effectively use the energy stored in the electric double layer capacitor and to recover and reuse the regenerative power obtained from the motor without waste, it was stored in the electric double layer capacitor according to the operating conditions of the motor. It is necessary to keep the amount of power appropriate.

  Specifically, when a power running operation of the electric motor is assumed, it is necessary to store power energy required for the power running drive in advance in an electric double layer capacitor. Conversely, when regenerative operation of the motor is expected, the amount of power stored in the electric double layer capacitor can be kept low so that the regenerative power can be reliably stored in the electric double layer capacitor, and the electric charge can be charged. It is necessary to provide a sufficient capacity.

  The present invention has been made in view of such circumstances, and its purpose is to appropriately control the amount of power stored in the capacitor in accordance with the operating condition of the load, and thereby the load through the capacitor. It is an object of the present invention to provide a load driving device that can efficiently perform the driving of the motor and accumulation of regenerative power recovered from the load.

In order to achieve the above-described object, a load driving device according to the present invention has a function of converting AC power supplied from an external power source into DC power, and a function of converting DC power into AC power and regenerating the external power source. AC / DC converter, a capacitor for storing DC power output from the AC / DC converter, DC power stored in the capacitor and / or DC power output from the AC / DC converter, An inverter that converts AC power with a controlled frequency to drive a load, collects regenerative power generated in the load, and accumulates it in the electric double layer capacitor;
In particular, the controller that controls the operation of the AC / DC converter is:
<a> Predicts the amount of power required for powering driving of the load or the amount of power regenerated from the load according to the state quantity of the load, and sets the DC voltage setting value for the AC / DC converter based on the predicted amount of power Control condition setting means for determining
<b> When the DC voltage detection value on the DC side of the AC / DC converter is smaller than the DC voltage set value, the power supply operation from the external power source is performed within a preset current limit value range. 1 control means;
<c> When the DC voltage detection value is larger than the DC voltage set value, the second control means for performing a power regeneration operation to the external power source within the range of the current limit value. Yes.

  Preferably, the current value limit value is preset as a value equal to or less than a maximum allowable current of the AC / DC converter. According to a third aspect of the present invention, the load comprises an electric motor that drives an elevator, and the state quantity of the load is given as information on the weight of the object that is raised and lowered by the elevator and its moving height. Specifically, the state quantity of the load includes the weight of the lifting gauge (hanging tool) for lifting and lowering the load and the weight of the load, and the position of the lifting gauge (hanging tool), or the weight of the lifting load and the lifting height in the crane. Given as information.

  The DC voltage set value is set to be high when the predicted amount of electric power as described in claim 4 indicates powering of a load such as when lifting a load, and the weight of the lifted load is reversed. It is set low when it indicates a regeneration of a load that uses the load to unload.

  According to the load driving device configured as described above, the controller that controls the operation of the AC / DC converter is regenerated from the amount of power required for powering driving of the load or the load according to the state quantity of the load. A power amount is predicted, and a DC voltage setting value for the AC / DC converter for controlling the power amount to be stored in the capacitor is determined based on the predicted power amount. The operation of the AC / DC converter is controlled depending on whether the DC voltage detection value on the DC side of the AC / DC converter, that is, the charging voltage (terminal voltage) of the capacitor is larger or smaller than the DC voltage setting value. To do. Specifically, when the charging voltage of the capacitor is smaller than the DC voltage set value, the AC / DC converter is operated to supply power from the external power source to the capacitor, and conversely, the charging voltage of the capacitor is the DC voltage. When the value is larger than the set value, the electric power regeneration operation for returning the electric power stored in the capacitor to the external power source is performed.

  Therefore, it is possible to appropriately control the charge amount of the capacitor in anticipation of the drive power amount of the load predicted according to the load state or the regenerative power amount from the load. Therefore, it is possible to stably drive the load via the capacitor and to reliably store the regenerative power obtained from the load in the capacitor. In addition, since the power supply operation and the power regeneration operation of the AC / DC converter are respectively performed within the range of preset current limit values in accordance with the charge amount of the capacitor, the above capacitor can be used without imposing an excessive burden on the capacitor. The amount of charge can be optimized.

Hereinafter, a load driving device according to an embodiment of the present invention will be described with reference to the drawings.
This load driving device is supplied from an external power source, for example, with a driving induction motor (motor) in a crane that lifts and lowers an article (luggage) and a lifter that moves an elevating stage for placing the article up and down. The electric motor is driven using AC power (for example, 200V power system three-phase AC power). In particular, the load driving device basically generates DC power from AC power using an AC / DC converter, and further generates AC power whose voltage and frequency are controlled from this DC power using an inverter. Load).

  That is, the load driving device according to the present invention includes an AC / DC converter 2 that converts AC power supplied from an external power source 1 into DC power, as shown in FIG. 2 includes a capacitor 3 for accumulating the DC power output from 2. The capacitor 3 is composed of, for example, an electric double layer capacitor that is small and has a large charge capacity. Further, the load driving device generates the AC power whose voltage and frequency are controlled from the DC power stored in the capacitor 3 and / or the DC power output from the AC / DC converter 1 to drive the load (motor) 4. An inverter 5 is provided. The inverter 5 has a function of converting the regenerative power into DC power, collecting it and storing it in the capacitor 3 when regenerative power is obtained from the load (electric motor) 4.

  The operation of the inverter 5 is controlled by a load controller 6 according to the driving state of the load 4. In particular, when the power required for driving the load 4 is positive (+), the load controller 6 controls the load 4 using the power stored in the capacitor 3 and / or the power obtained from the AC / DC converter 2. When power driving is performed and the power required for driving the load 4 is negative (−) and power is regenerated through the load 4, the regenerative power is recovered and the capacitor 3 is charged. ing.

  The operation of the AC / DC converter 2 is controlled by the power supply controller 7 according to the DC side voltage, specifically, the charging voltage (terminal voltage) of the capacitor 3. In particular, the power controller 7 predicts the amount of power required to drive the load 5 by the inverter 3 or the amount of regenerative power obtained from the load 5 according to the state of the load 5 (prediction function 7a), and the predicted power The DC voltage setting set value Vfix for controlling the charge amount (accumulated power amount) of the capacitor 3 is set according to the amount (voltage setting function 7b). Then, the charging voltage Vsenc of the capacitor 3 detected in the DC system is compared with the DC voltage set value Vfix described above, and the AC / DC converter 2 is operated to supply power or regenerate according to the comparison result. Thus, the charge amount of the capacitor 3 is controlled.

Specifically, the charge amount U of the capacitor 3 is expressed as [U = (1/2) CV ² ] when its capacity is C, and is proportional to the square of the charge voltage V as shown in FIG. Change. In other words, when the voltage (applied voltage) applied to the capacitor 3 is higher than the terminal voltage, there is a margin in the electric capacity (electric energy amount) that can be stored in the capacitor 3, so that the terminal voltage reaches the applied voltage. Until the capacitor 3 is charged. On the other hand, when the voltage (applied voltage) applied to the capacitor 3 is lower than the terminal voltage, since the electric capacity (electric energy amount) stored in the capacitor 3 is excessive, the terminal voltage reaches the applied voltage. Until the capacitor 3 is discharged.

  The power supply controller 7 pays attention to the fact that the amount of charge in the capacitor 3 changes in proportion to the square of the DC voltage applied to the capacitor 3 as described above, and determines the amount of power (required power) required to drive the load 4. As described above, the output voltage of the AC / DC converter 2 is set to the DC voltage setting value in order to store in the capacitor 3 or to store the electric energy (regenerative electric energy) obtained from the load 4 in the capacitor 3 with certainty. It is set as Vfix.

That is, when the load 4 is an elevator such as a crane, when the load is lifted by winding a wire for hanging the load, a power running power is required for driving the motor. The electric power Udriv required to drive the vehicle is calculated from, for example, the weight W of the load, the maximum lifting height Hmax of the crane, and the current height position Hnow.
Can be predicted (calculated) as However, K1 is a coefficient depending on the mechanical efficiency and the electric efficiency during the power running operation. Conversely, when unloading a load, regenerative power is generated in the motor when the wire is rewound against the weight W of the load. And the regenerative power Uback is the maximum suspension height of the crane as Hmin. Uback = K2W (Hnow-Hmin)
Can be predicted (calculated) as However, K2 is a coefficient depending on the mechanical efficiency and the electric efficiency during the regenerative operation.

  Therefore, if each information of the weight W of the load and the current height position Hnow which is the state of the crane is obtained, the power running power Udriv necessary for lifting the load of weight W from the current height Hnow to the height Hmax. Alternatively, it is possible to predict the regenerative power Uback obtained when the baggage is lowered from the current height Hnow to the height Hmin. Therefore, when lifting a load, the power running power Udriv can be obtained from the capacitor 3, and when unloading the load, the regenerative power Uback can be stored in the capacitor 3 so that the power can be stored in the capacitor 3 in advance. In order to adjust the amount, the output voltage of the AC / DC converter 2 is set as a DC voltage set value Vfix.

  Then, the charging voltage (terminal voltage) Vsenc of the capacitor 3 detected in the DC system is compared with the DC voltage set value Vfix (determination function 7c), and the AC / DC converter 2 is determined according to the determination result. The power supply operation (power supply operation function 7d) or the power regeneration operation (power regeneration operation function 7e) is performed. In particular, when the charging voltage (terminal voltage) Vsenc of the capacitor 3 is lower than the DC voltage setting value Vfix, the power supply operation is executed until the charging voltage Vsenc reaches the DC voltage setting value Vfix as shown in FIG. On the contrary, when the charging voltage Vsenc of the capacitor 3 is higher than the DC voltage setting value Vfix, the power regeneration operation is executed until the charging voltage Vsenc reaches the DC voltage setting value Vfix.

  As a result, the charging capacity of the capacitor 3 is adjusted so that the power required for powering driving of the load 4 is stored in the capacitor 3 in advance, or the charging margin capacity in the capacitor 3 exceeds the regenerative power obtained from the load 4. Is done. The power supply operation of the AC / DC converter 2 is an operation in which the AC power supplied from the external power source 1 is converted to DC power and the capacitor 3 is charged. The power regeneration operation is stored in the capacitor 3. This is an operation of converting the direct current power to alternating current power and returning it to the external power source 1 (reverse supply). Further, these power supply operation and power regeneration operation are performed under a certain current value limit.

  Specifically, the power supply control unit 7 first determines whether or not the operating condition is satisfied as shown in a schematic control procedure in FIG. 3 (step S1). When the operating condition is satisfied, the DC / DC converter 2 takes in the DC voltage set value Vfix set based on the predicted electric energy to be output as an initial setting process, and a sensor (voltmeter not shown) is shown. The DC voltage (charged voltage of the capacitor 3) detected at (1) is taken in the DC voltage detection value Vsenc (step S2). At this time, a current limit value Isup at the time of power supply in the AC / DC converter 2 and a current limit value Ireg at the time of power regeneration are taken in, respectively, and a direct current indicating a range of output voltage that can be controlled by the AC / DC converter 2. The voltage upper limit value Vmax and the DC voltage lower limit value Vmin are taken in, respectively. The current limit values Isup and Ireg at the time of power supply and power regeneration may be arbitrarily set within the allowable maximum current range determined by the specifications of the AC / DC converter 2.

  Thereafter, the power supply control unit 7 first compares the DC voltage set value Vfix set according to the state of the load with the DC voltage detection value Vsenc to determine whether or not the required amount of power is stored in the capacitor 3. <Step S3>. When it is confirmed that the DC voltage detection value Vsenc is equal to the DC voltage setting value Vfix and the required amount of power is stored in the capacitor 3, the control on the AC / DC converter 2 is stopped and Return <Step S4>.

  On the other hand, if the DC voltage setting value Vfix and the DC voltage detection value Vsenc are different, it is determined whether or not the DC voltage detection value Vsenc is higher than the DC voltage setting value Vfix <step S5>. When the DC voltage detection value Vsenc is higher than the DC voltage setting value Vfix, it is determined that the capacitor 3 stores more power than the desired amount of power, so that the AC / DC converter 2 is powered. Regenerative operation. At this time, it is determined whether or not the DC voltage detection value Vsenc exceeds the DC voltage upper limit value Vmax <step S6>. If the DC voltage detection value Vsenc is high, the power stored excessively in the capacitor 3 is determined. In order to quickly recover the energy to the external power source 1, the AC / DC converter 2 is released from the above-described current limitation and the power regeneration operation is performed (step S7). However, when the DC voltage detection value Vsenc is low, the AC / DC converter 2 is set to a constant current under the current limit value Ireg described above in order to gradually recover the charging power of the capacitor 3 to the external power source 1. The power regeneration operation is performed at <Step S8>.

  On the other hand, when the DC voltage detection value Vsenc is lower than the DC voltage setting value Vfix, it is determined that the desired amount of electric power is not stored in the capacitor 3, so the AC / DC converter 2 Power supply operation. At this time, it is determined whether or not the DC voltage detection value Vsenc is less than the DC voltage lower limit value Vmin <step S9>. If the DC voltage detection value Vsenc is less than the DC voltage lower limit value Vmin, the capacitor 3 In order to quickly charge the amount of charge to a range that guarantees the operating characteristics of the AC / DC converter 2, the AC / DC converter 2 is released from the above-described current limitation and the power supply operation is performed (step S10). However, when the DC voltage detection value Vsenc exceeds the DC voltage lower limit value Vmin, the AC / DC converter 2 is set to the current limit value Isup described above in order to gradually charge the capacitor 3 to a desired charge amount. A power supply operation is performed at a constant current under the current limit (step S11).

  That is, the DC voltage detection value Vsenc in the DC system that is the charging voltage of the capacitor 3 is within the range of the DC voltage upper limit value Vmax and the DC voltage lower limit value Vmin that can control the charge amount of the capacitor 3 by the AC / DC converter 2. In some cases, according to the voltage relationship with the DC voltage setting value Vfix that controls the charge amount of the capacitor 3, the AC / DC converter 2 is operated to supply power or regenerate under the above-mentioned current limiting conditions, and the capacitor 3 The charge amount is controlled to be constant. However, when the DC voltage detection value Vsenc exceeds the DC voltage upper limit value Vmax and the charge amount of the capacitor 3 is excessive, the AC / DC converter 2 is forcibly regenerated and the excess power energy is supplied to the external power source 1. When the DC voltage detection value Vsenc is less than the DC voltage lower limit value Vmin, the voltage (charge amount) of the capacitor 3 is reduced to a voltage that the AC / DC converter 2 cannot control. In order to prevent this, the AC / DC converter 2 is forcibly supplied with power.

  Thus, according to the operation control of the AC / DC converter 2 as described above, the amount of power stored in the capacitor 3 is adjusted in advance in consideration of the amount of power required to drive the load 4 and the amount of regenerative power obtained from the load 4. be able to. Therefore, when the load 4 is driven by power using the power stored in the capacitor 3 and regenerative power is obtained from the load 4, the regenerative power can be reliably stored in the capacitor 3. The power consumed by driving the load 4 by the load driving device is supplied with constant current or constant power in advance to optimize the charge amount of the capacitor 3, and surplus power accumulated in the capacitor 3 is supplied to the external power source 1. It becomes possible to regenerate efficiently. Therefore, effects such as the ability to effectively reduce the power consumption as the load driving device can be achieved.

  The present invention is not limited to the embodiment described above. For example, in an overhead crane installed in a factory, etc., the basic operation is to lift the load, move it to another location, and then drop the load to that location. The amount of regenerative electric power obtained at the time of the lowering operation is predicted, and the amount of power to be stored in the capacitor 3 is determined in consideration of the power running power amount and the regenerative power amount input to and output from the load 4. The DC voltage set value Vfix may be set.

  Moreover, although driving | operation of elevators, such as a crane and a lifter, was demonstrated here as an example, if regenerative electric power is obtained from the load 4, it can apply similarly. Specifically, the load 4 can be accelerated and decelerated, powering energy can be consumed during acceleration, and the drive can be similarly used for driving a load that can recover regenerative energy during deceleration. Specific examples of elevators include container transfer (transport) cranes in port facilities, jib climbing cranes used in building construction, stacker cranes in automatic warehouses, and lifters in mechanical multilevel parking lots. .

  When the load 4 moves up and down the lift stage such as a lifter or the like, the weight Wfix of the lift stage and the weight W of the load mounted on the lift stage are respectively input, and the power running power necessary for the lift is input. Uneed and regenerative power Uback may be predicted. In this case, the power running power Uneded and the regenerative power Uback vary depending on whether or not a load is loaded. In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

The block diagram which shows the principal part schematic structure of the load drive device which concerns on one Embodiment of this invention. The figure which shows the processing concept of the electric power supply to the capacitor | condenser for demonstrating one Embodiment of this invention, and the electric power regeneration from the said capacitor | condenser. The figure which shows the example of the operation control procedure of the alternating current and direct current | flow inverter in the load drive device which concerns on one Embodiment of this invention.

Explanation of symbols

1 External power supply 2 AC / DC converter 3 Capacitor (electric double layer capacitor)
4 Load (motor)
5 Inverter 6 Load controller 7 Power supply controller 7a Prediction function 7b Voltage setting function 7c Judgment function 7d Power supply operation function 7e Power regeneration operation function

Claims (4)

An AC / DC converter having a function of converting AC power supplied from an external power source into DC power, and a function of converting DC power into AC power and regenerating the external power source;
A capacitor for storing the DC power output from the AC / DC converter;
The DC power stored in the capacitor and / or the DC power output from the AC / DC converter is converted to AC power with a controlled voltage and frequency to drive the load, and the regenerative power generated in the load An inverter that collects and accumulates in the capacitor,
The controller for controlling the operation of the AC / DC converter is:
The amount of power required for powering driving of the load or the amount of power regenerated from the load is predicted according to the state quantity of the load, and a DC voltage setting value for the AC / DC converter is determined based on the predicted amount of power. Control condition setting means;
When the DC voltage detection value on the DC side of the AC / DC converter is smaller than the DC voltage set value, the first control for performing the power supply operation from the external power source within a preset current limit value range. Means,
Load control, wherein the DC voltage detection value is greater than the DC voltage set value, and includes a second control means for performing a power regeneration operation to the external power source within the range of the current limit value. apparatus.   The load driving device according to claim 1, wherein the current value limit value is set in advance as a value equal to or less than a maximum allowable current of the AC / DC converter.   2. The load driving device according to claim 1, wherein the load is an electric motor that drives an elevator, and the state quantity of the load includes a weight of an object that is raised and lowered by the elevator and movement height information thereof.   2. The load driving device according to claim 1, wherein the DC voltage set value is set to be high when the predicted power amount indicates power running of the load, and is set to be low when indicating the regeneration of the load.

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