JP2014068500A - Motor control apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control apparatus which comprises a regeneration device for returning regenerative power generated by e.g., a hoist wind-up motor or the like to a three-phase AC power source and in which the number of detectors for synchronization to a three-phase AC power supply voltage can be reduced.SOLUTION: In a regeneration device 5 for returning regenerative energy (regenerative power) generated by a motor 4 to a three-phase AC power source 1, a regenerative signal generation section 53 estimates and retains voltage waveforms of phases in the three-phase AC power source 1 from output of a photocoupler as a voltage detector 51 which is provided at one spot between phases of the three-phase AC power source 1 and output of a current detector 52 provided in one phase. When the generation of the regenerative power is detected by a voltage detection section 54, the regenerative signal generation section 53 controls driving of a converter 55 so as to present the retained voltage waveform.

Description

  The present invention relates to an electric motor control device including a regenerative device that drives and controls a hoist hoisting motor, for example, and returns regenerative power from the electric motor to a power source.

  In conventional motor control devices, the regenerative energy (regenerative power) generated by the motor is consumed by changing it into heat with a braking resistor, or stored in a capacitor (external battery) and reused when the motor is driven. Methods have been implemented, such as converting the power of the power source frequency to the power source and returning it to the power source, or returning the motor driving frequency and power source frequency directly to the power source. (For example, Patent Document 1)

JP 2009-240108 A

  As described above, there are a number of methods for processing regenerative power in a conventional motor control device. However, the method using a braking resistor consumes waste by changing the regenerative power to heat and requires countermeasures against generated heat. The method of storing electricity in the capacitor requires a large capacity capacitor. The method of returning directly to the power supply cannot be used in the variable speed region when the motor is started and stopped, and therefore must be used in combination with a method of using a braking resistor or a capacitor. The method of using the regenerative device is the best method because it saves energy, but since it needs to be controlled in synchronization with the power supply voltage phase, many detections are required to detect the voltage and current of each phase of the three-phase AC power supply. There was a problem that the equipment was required and the price was high.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electric motor control device that can reduce the number of detectors for synchronizing the output from the regenerative device with the power supply voltage phase. To do.

  An electric motor control device according to the present invention includes a regenerative device that drives and controls a motor by variable frequency driving an inverter with a DC power source obtained by rectifying a three-phase AC power source, and returns regenerative power from the motor to the three-phase AC power source. In the electric motor control device provided, the regenerative device has a voltage waveform of the three-phase AC power supply from an output of a voltage detector provided at one location between the phases of the three-phase AC power supply and an output of a current detector provided in one phase. And a regenerative signal generator for driving and controlling the converter so as to derive an output synchronized with the estimated voltage waveform.

  According to the motor control device of the present invention, the regenerative device is configured to output the voltage of the three-phase AC power source from the output of the voltage detector provided at one location between the phases of the three-phase AC power source and the output of the current detector provided in one phase. Since the regenerative signal generation unit that drives and controls the converter so as to estimate the waveform and derive the output synchronized with the estimated voltage waveform is provided, there is an effect that the number of detectors can be reduced and the price can be reduced.

It is a block diagram which shows the structure of the electric motor control apparatus in Embodiment 1 of this invention. It is explanatory drawing which shows the relationship between the driving | running pattern of the electric motor controlled by the electric motor control apparatus in Embodiment 1 of this invention, and regenerative energy. It is explanatory drawing explaining the relationship between the output of a photocoupler as a voltage detector of the electric motor control apparatus in Embodiment 1 of this invention, and a voltage waveform. It is explanatory drawing explaining the relationship between the power supply voltage of the electric motor control apparatus in Embodiment 1 of this invention, a power supply phase voltage, and a power supply current. It is a block diagram which shows the structure of the electric motor control apparatus in Embodiment 2 of this invention.

Embodiment 1 FIG.
Hereinafter, the electric motor control apparatus in Embodiment 1 of this invention is demonstrated based on FIGS. 1-4. FIG. 1 is a block diagram showing a configuration of an electric motor control device according to Embodiment 1 of the present invention, and FIG. 2 shows a relationship between an operation pattern of the electric motor controlled by the electric motor control device according to Embodiment 1 of the present invention and regenerative energy. FIG. 3 is an explanatory diagram for explaining the relationship between the output of the photocoupler as a voltage detector of the motor control device and the voltage waveform in the first embodiment of the present invention, and FIG. 4 is a first embodiment of the present invention. It is explanatory drawing explaining the relationship of the power supply voltage of the electric motor control apparatus in FIG.

  In FIG. 1, a commercial three-phase AC power source 1 is converted (rectified) into a direct current and is applied to both ends of a smoothing capacitor 2 to become a direct current power source. Using this DC power supply, the inverter 3 is driven and controlled by a control device (not shown) to output variable frequency power, and the motor 4 used in a hoist such as a hoist is driven. The relationship between the operation pattern of the electric motor 4 at this time and regenerative energy is shown in FIG. In FIG. 2, in a state where the electric motor 4 is driven, regenerative energy (regenerative power) is generated from the high speed hoisting operation until the rotation speed is lowered and stopped, and in the entire driving range during the lowering operation. The DC voltage across the capacitor 2 rises. The generated regenerative power is generated by the regenerative device 5 which will be described in detail later, and an AC voltage synchronized with the three-phase AC power source 1 is generated and returned to the three-phase AC power source 1.

  As shown in FIG. 1, the detailed configuration of the regenerative device 5 is such that a photocoupler as a voltage detector 51 is connected between one R phase and S phase of the three-phase AC power source 1. A current detector 52 is provided in the one R phase. Outputs from the voltage detector 51 and the current detector 52 are input to a regenerative signal generator 53, and the regenerative signal generator 53 estimates and holds the voltage waveform of the three-phase AC power supply 1 from these inputs. . The regenerative signal generator 53 receives an output from the voltage detector 54 that detects the voltage across the capacitor 2. When the voltage across the capacitor 2 rises above a predetermined value, the regenerative power is generated. As generated, the regenerative signal generator 53 drives the converter 55 so that an output synchronized with the phase of the held voltage waveform is generated. The converter 55 is configured by bridge-connecting six switching semiconductors such as IGBTs (insulated gate bipolar transistors). The output from the converter 55 is returned to the three-phase AC power source 1 as smooth AC power by the reactor 56 inserted in each phase of the three-phase AC power source 1.

  Next, the operation in the regenerative signal generator 53 will be described. As shown in FIG. 3, from the rectangular wave output from the photocoupler as the voltage detector 51 connected to one place between the phases of the three-phase AC power source 1, the H (high) level time and L of an arbitrary half cycle Each (low) level time is measured, and it is estimated that the center of the H level is the peak of the power supply voltage waveform and the center of the L level is the zero cross of the power supply voltage waveform, assuming that the next half cycle is the same. Further, since the AC power supply voltage and the current have the relationship shown in FIG. 4 since the powering operation is performed when the hoisting machine is started, the positive and negative voltages are determined from the output signal of the current detector 52 when the hoisting machine is started. Estimate the above zero crossing or peak. Since the voltage phase and voltage peak value of the commercial three-phase AC power source 1 are fixed in the relationship shown in FIG. 4, if the voltage waveform at one location can be estimated, the positive / negative and zero-cross or peak of the voltage of all three phases are You can estimate and keep this information. A DC voltage across the capacitor 2 is detected and inputted to the regenerative signal generator 53 by the voltage detector 54, and if this DC voltage exceeds a predetermined value, regenerative energy is generated and regenerative energy is generated. The signal generation unit 53 generates a switching pattern so that the voltage waveform of the estimated AC power supply is held and applies it to the gate of the switching semiconductor constituting the converter 55, so that the voltage phase of the three-phase AC power supply 1 is obtained. The converter 55 is driven in synchronization, and regenerative energy is regenerated to the three-phase AC power source 1. As described above, it is possible to estimate the power supply voltage phase by one voltage detector 51 and one current detector 52 without detecting all three-phase voltage waveforms, so that the number of detectors can be reduced and the price can be reduced.

Embodiment 2. FIG.
In the first embodiment, the case where the phase order of the three-phase AC power supply 1 is known and fixed has been described. FIG. 5 shows a case where the phase order is unknown or may be switched. FIG. 5 is a block diagram showing an electric motor control apparatus according to Embodiment 2 of the present invention, and the same or similar parts as those in FIG. 1 of Embodiment 1 are denoted by the same reference numerals. As shown in FIG. 5, the current detector 52 is inserted into two phases, and the regenerative signal generating unit 53 uses the relationship shown in FIG. 4 from the output signal of the two-phase current detector 52 when the hoisting machine is started. Estimate the phase order of the phases. As described above, even when the phase order of the three-phase AC power supply 1 is unclear, the phase order can be estimated only by using two current detectors 52. Other parts are the same as those in the first embodiment, and a description thereof will be omitted.
It should be noted that within the scope of the present invention, the embodiments can be freely combined, or the embodiments can be appropriately modified or omitted.

1 Three-phase AC power supply, 2 capacitors, 3 inverters, 4 motors, 5 regenerative devices, 51
Voltage detector, 52 current detector, 53 regenerative signal generator, 54 voltage detector, 55 converter, 56 reactor.

Claims (4)

  In the motor control device comprising a regenerative device that drives and controls the electric motor by driving the inverter at a variable frequency with a DC power source obtained by rectifying the three-phase AC power source, and that returns the regenerative power from the motor to the three-phase AC power source. The apparatus estimates the voltage waveform of the three-phase AC power supply from the output of the voltage detector provided at one location between the phases of the three-phase AC power supply and the output of the current detector provided in one phase, and the estimated voltage waveform An electric motor control device comprising a regenerative signal generation unit for driving and controlling the converter so as to derive an output synchronized with the motor.   In the motor control device comprising a regenerative device that drives and controls the electric motor by driving the inverter at a variable frequency with a DC power source obtained by rectifying the three-phase AC power source, and that returns the regenerative power from the motor to the three-phase AC power source. The apparatus estimates the voltage waveform and phase sequence of the three-phase AC power source from the output of the voltage detector provided at one location between the phases of the three-phase AC power source and the output of the current detector provided in two phases, and the estimation An electric motor control device comprising a regenerative signal generation unit that drives and controls the converter so as to derive the output synchronized with the voltage waveform and the phase order.   The motor control apparatus according to claim 1, wherein the voltage detector is a photocoupler. The motor control device according to any one of claims 1 to 3, wherein the motor is a hoisting hoist motor.