JP2014124014A - Pwm converter device and elevator device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a PWM converter device and an elevator device including a power supply frequency discrimination function with which it is possible to highly accurately discriminate a power supply frequency with a simple construction at a low cost and reflect a result of the discrimination in a power supply voltage phase.SOLUTION: A PWM converter device, which performs current control by converting an AC current into a current on a d axis and a current on a q axis using an AC power supply phase to thereby allow a power converter to perform power conversion, includes: first means for detecting a zero-cross point of an AC voltage waveform and generating a rectangular signal; second means for discriminating, through time measurement of a rectangular width of the rectangular signal, whether a power supply frequency of an AC power supply is 50 Hz or 60 Hz; third means for giving a first fixed value when the power supply frequency is 50 Hz and giving a second fixed value when the power supply frequency is 60 Hz; and fourth means for performing fixed value addition processing at every fixed time interval in a period of the rectangular width and generating a sine waveform correspondingly to an addition value.

Description

  The present invention relates to a PWM converter device and an elevator device that perform power conversion between AC power and DC power, and more particularly to a PWM converter device and an elevator device that are suitable for use in regions where the frequency of AC power is different.

  As a power converter that can extremely reduce a harmonic current generated when power conversion is performed between AC power and DC power, a PWM converter device is widely used. The PWM converter device is widely used as, for example, an electric motor driving device that drives a hoisting machine of an elevator apparatus.

  In the PWM converter device, a filter reactor is connected to an AC power source on the input side, and a smoothing capacitor and a load are connected between DC terminals on the output side. Therefore, when power is supplied from the power supply side to the load side, the PWM converter is controlled so that a sinusoidal input current flows in the same phase as the power supply voltage. Further, when power is regenerated from the load side to the power source side, the PWM converter is controlled so that a sinusoidal input current flows in a phase opposite to the power source voltage.

  Specifically, the amplitude command of the input current is given so that the DC voltage of the smoothing capacitor becomes a predetermined value, and the current command value synchronized with the power supply voltage phase is set so that the input current detection value matches this command value. The AC input voltage of the PWM converter is controlled.

  More specifically, vector control is employed in the control of the PWM converter device, and when performing current control, current feedback control is divided into q-axis current (torque generation current) and d-axis current (magnetic flux generation current). I do. In the process of converting the three-phase alternating current on the power supply side into two phases and further converting into a dq axis component, the power supply voltage phase is used as a reference phase signal for the current signal.

  As described above, in the control of the PWM converter, it is necessary to use a sinusoidal current having the same phase as the power supply voltage phase or an opposite phase, and as a precondition for this, a technique for accurately and simply obtaining the power supply voltage phase is required. When determining the power supply voltage phase, it is necessary to sufficiently consider that there are cases of the forward order and the reverse order depending on the power supply connection order on the input side of the converter device. If the wiring phase sequence of the input terminals of the converter device does not match the internal phase sequence of the control system, there is a risk that overcurrent at startup and normal control cannot be performed.

  Thus, in order to control the PWM converter, it is indispensable to detect the power supply voltage phase, the DC voltage, and the input current to the converter. Such a sine wave PWM converter has been developed for a long time, and a number of methods have been proposed. The techniques disclosed in Patent Document 1 and Patent Document 2 are examples of these.

JP 2012-6715 A JP 2011-73849 A

  The commercial power system has a power supply with a frequency of 50 Hz / 60 Hz. For this reason, in actual operation of the PWM converter, it is necessary to consider the power supply voltage phase according to the region where it is used. The length of one cycle of the power supply voltage phase is 20 ms in the 50 Hz system, but 16.67 ms in the 60 Hz system.

  In this regard, when a manufacturer delivers a product, a product in which a power supply voltage phase is set for a 50 Hz system and a 60 Hz system is delivered to each region. Alternatively, for example, a switching operation is performed such as a method of setting whether the frequency is 50 Hz / 60 Hz in the on / off state of the switch, or storing whether the frequency is 50 Hz / 60 Hz in the storage area of the elevator control unit. In some cases, the method was adopted.

  In addition, although patent document 1 is disclosing the phase control technique of an elevator apparatus, there is no description of the structure which switches 50Hz / 60Hz by a phase signal of a power supply, and performs phase control. Japanese Patent Laid-Open No. 2004-260688 does not describe a method of measuring and switching the phase signal of the power supply, although there is control of switching of 50 Hz / 60 Hz.

  In any of the above cases that are dealt with by switching the setting, there is a possibility that an overcurrent at startup or normal control cannot be performed due to an incorrect setting of the power supply frequency. Even if the setting is switched, a circuit technique for obtaining the power supply voltage phase accurately and simply is required. On the other hand, if the frequency of the commercial AC power source used can be automatically determined by the converter device alone, the power source frequency need not be set in advance.

  In view of the above, an object of the present invention is to provide a PWM converter device having a power frequency discriminating function capable of discriminating a power frequency with high accuracy with a simple configuration and low cost and reflecting it in the power voltage phase. And providing an elevator apparatus.

  In view of the above, in the present invention, in order to perform power conversion by the power converter, the AC converter converts current into d-axis and q-axis currents to control the current and uses the AC power source phase for the conversion. The first means for detecting the zero-cross point of the AC voltage waveform to generate a rectangular signal, the second means for identifying whether the AC power supply frequency is 50 Hz or 60 Hz by measuring the rectangular width of the rectangular signal. Means, a third means for giving a first constant value at 50 Hz and a second constant value at 60 Hz, adding a constant value at regular time intervals within a rectangular width period, and corresponding to the added value And a fourth means for generating a sinusoidal waveform.

  According to the present invention, a PWM converter device having a power source frequency discriminating function capable of discriminating a power source frequency with high accuracy at a simple configuration and at low cost and reflecting it in a power source voltage phase, and an elevator apparatus using the same Can be provided.

The figure which showed centering on the function of a power supply phase calculating part and a current control part. 1 is an overall schematic configuration diagram of an elevator control apparatus according to an embodiment of the present invention. The block diagram which shows the processing function in a power supply phase calculating part. The wave form diagram which shows the processing content in a power supply phase calculating part. The processing flow which discriminate | determines whether the process of a power supply phase calculating part is executable. The wave form diagram explaining the specific processing content of a power supply phase calculating part. The figure which showed the procedure at the time of processing by software by CPU etc. FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, an overall schematic configuration of an elevator control apparatus according to an embodiment of the present invention will be described with reference to FIG.

  FIG. 2 shows an overall configuration when the PWM converter device is applied to an elevator apparatus. Of these, the elevator apparatus is composed of a car rope 8 connected at one end via a sheave 7, a wire rope 18 connected to a counterweight 9 at the other end, and a hoisting machine 6 (electric motor) for rotating the sheave. In general, the configuration on the load side of the electric motor 6 may be of any application, and an elevator apparatus is an example.

  The PWM converter device 100 determines the power to be supplied to the electric motor 6, and the PWM converter device 100 includes a power main circuit 101 and a control device 102.

  Among them, the power main circuit 101 is a DC circuit including a filter reactor 2 for reducing harmonics, a converter 3 for converting AC to DC power, and a smoothing capacitor 4 between a commercial power source (AC system) 1 and an electric motor 6. The inverter 5 converts DC to AC. With this configuration, the frequency (50 Hz or 60 Hz) of the commercial power source (AC system) 1 is converted to an arbitrary frequency and AC power is supplied to the motor 6.

  Various configurations of the control device 102 can be applied depending on the type of load, but the current control unit 16 and the PWM control circuit are provided, and the ignition timing of the converter 3 is determined by the PWM signal. The control device 102 also gives an ignition signal to the inverter, but the description is omitted here.

  The current control unit 16 performs vector control, and obtains a q-axis current (torque generation current) command signal Icq * and a d-axis current (magnetic flux generation current) command signal Icd * as current control command signals. FIG. 2 shows an example in which cascade control is performed by the DC voltage control unit 15 and the current control unit 16 as an example of control for performing elevator control. However, depending on the application target on the load side, the DC voltage control unit 15 may be It may be replaced with a speed control unit.

  Various signals are taken in for the control of the control device 102. First, the DC voltage Vd is detected by the voltage detector 10. The DC voltage detection value Vd is compared and calculated as a feedback signal in the DC voltage control unit 15 with the command value Vd *, and a q-axis current command signal Icq * is generated.

  The alternating current Ic is detected by the current detector 12 and used as a feedback signal for the current command signals Icq * and Icd *.

  Further, the three-phase AC voltage Vc is detected by the power supply phase detector 13 and supplied to the power supply phase calculator 14 for the control of the control device 102. FIG. 3 is a block diagram showing processing functions in the power supply phase calculation unit 14.

  The rectangular circuit 144 of the power supply phase calculation unit 14 performs a rectangular process on each phase voltage, detects the zero cross point of the AC voltage waveform, outputs “1” in the positive half wave, and outputs the negative half wave in the negative half wave. A pulse signal that becomes “0” is generated.

  The order of rising and falling of each rectangular phase voltage is given to the phase order detection circuit 143 and compared with a predetermined order held in advance to confirm that it has changed in the correct order. This confirms that the correct connection has been made.

  As described above, in order to control the PWM converter, the connection phase sequence of the input terminal of the converter device must match the internal phase sequence of the control system, and the processing in the power supply phase calculation unit 14 determines the connection phase sequence. It can be said that a phase sequence detection circuit for taking in the control system (for example, control CPU) is configured.

  Further, the timer unit 146 of the power supply phase calculation unit 14 of the present invention measures the edge detection cycle of the rectangularized one-phase pulse signal by the pulse count number. In the frequency identification unit 145, for example, the absolute value of the difference between the previous pulse count number and the current pulse count number is stored in advance as the pulse count number of the cycle of the power supply frequency (preset values: 50 Hz, 60 Hz, abnormal frequency). By comparing, the power supply frequency is determined. As a result, 50 Hz and 60 Hz are identified, and other abnormal frequencies are detected.

  FIG. 4 is a waveform diagram showing the processing contents in the power supply phase calculation unit 14. The sinusoidal AC voltage waveform is rectangularized when the voltage value is zero, and the positive half-wave section is “1” and negative. A pulse signal in which the half-wave section of “0” is “0” is generated. Then, the time measurement between the rising time points (or the falling time points) is measured as the pulse count number. The length of the one-cycle power supply voltage phase thus measured is 20 ms for the 50 Hz system and 16.67 ms for the 60 Hz system.

  For this reason, the pulse count number (preset value) of the cycle of the power supply frequency held in advance in the control CPU is a pulse number P50 corresponding to 20 ms for 50 Hz identification, and a pulse corresponding to 16.67 ms for 60 Hz identification. The number P60 is provided. Further, as the upper and lower limit values for identifying the abnormal frequency, a pulse number Pexu corresponding to 22 ms for identifying the lower limit frequency and a pulse number Pexo corresponding to 15 ms for identifying the upper limit frequency are provided.

  A first constant value L50 and a second constant value L60 are stored and held in the control constant storage memory 141 of the power supply phase calculation unit 14. In the control constant storage memory 141, when a pulse number P50 corresponding to 20 ms prepared for 50 Hz identification is detected, the first constant value L50 is given to the integration unit 142 to output a 50 Hz sine wave. When the number of pulses P60 corresponding to 16.67 ms prepared for 60 Hz identification is detected, the second constant value L60 is given to the integrator 142 to output a 60 Hz sine wave. The 50 Hz or 60 Hz sine wave obtained by using the first constant value L50 or the second constant value L60 is the power supply phase information given to the current control unit 16. A method of obtaining 50 Hz and 60 Hz sine waves from the first and second constant values L50 and L60 will be described later with reference to FIGS.

  When it is detected that the upper and lower limit values for abnormal frequency identification are deviated, emergency measures such as stopping the operation of the PWM converter are executed.

  In the processing in the power supply phase calculation unit 14, it is desirable to measure the pulse count multiple times in order to prevent erroneous detection of the power supply frequency. For example, 10 measurements are performed, and the average value of 8 measurement results excluding the maximum and minimum values is used to determine whether the power supply frequency is 50 Hz, 60 Hz, or a frequency abnormality. Is good.

  In addition, since the same measurement data may be read as the measurement period of the pulse count number, it is desirable that the measurement be performed at a period of about 40 ms, which is longer than the period of the power supply frequency (20 ms in the case of 50 Hz).

  Further, since the power supply frequency is determined to be 50 Hz or 60 Hz depending on the area to be used, it is not necessary to always measure the pulse count number. Since there is a possibility that the elevator cannot be operated due to detection of an abnormality in the power supply frequency or the like, it is desirable not to operate the elevator while the elevator is running, but to perform it while the elevator is stopped.

  FIG. 5 is a processing flow for determining whether or not the processing of the power supply phase calculation unit 14 can be executed. Here, stop of the elevator is determined in processing step S1. When the elevator is stopped, the process proceeds to processing step S2, and the power supply frequency determination function is enabled. When the elevator is traveling, the process proceeds to process step S3, and the power supply frequency determination function is determined to be inoperable.

  FIG. 1 is a diagram mainly showing the functions of the power supply phase calculation unit 14 and the current control unit 16. In this figure, functions other than the power supply phase calculation unit 14 and the current control unit 16 are the same as described in FIG.

  In FIG. 1, first, main circuits and functions constituting the current control unit 16 are a dq-axis current generation unit 161, proportional-integral adjustment circuits 162 and 163, a control voltage generation circuit 164, and the like. Among these, the dq-axis current generation unit 161 converts the three-phase alternating currents Ir, Is, It into orthogonal two-axis components Iα, Iβ, and further converts them into dq-axis currents Icd, Icq. In this conversion process, the power supply phase signal θcd obtained by the power supply phase calculation unit 14 is used.

  The control voltage generation circuit 164 converts the dq-axis control voltage signals Ed * and Eq * calculated by the proportional-plus-integral adjustment circuits 162 and 163 into orthogonal two-axis components Eα and Eβ, and further controls the three-phase control voltages Ecr *, Convert to Ecs * and Ect *. Also in this inverse conversion process, the power supply phase signal θcd obtained by the power supply phase calculation unit 14 is used. It should be noted that how to use the power supply phase signal θcd in the conversion and inverse conversion in the dq-axis current generation unit 161 and the control voltage generation circuit 164 is clear in many literatures and patent publications of vector control. Omit.

  The power supply phase signal θcd used for the conversion process in the dq-axis current generation unit 161 and the control voltage generation circuit 164 is a sine wave waveform synchronized with the voltage of the AC system, and this waveform is formed in the power supply phase calculation unit 14. Is done. Further, this waveform can output both 50 Hz and 60 Hz in response to the result of the processing described in FIG.

  The specific processing contents of the power supply phase calculation unit 14 will be described using the processing waveforms of FIG. As described above, in the processing in the power supply phase calculation unit 14, the AC voltage Vc is input, the AC voltage Vc is rectangularized, the zero cross point of the AC voltage waveform is detected, and the positive half-wave ” 1 "is output, and a pulse signal Vc1 that is" 0 "in the negative half-wave is generated. Further, in the processing by the power supply phase calculation unit 14, as described above, the first constant value L50 is obtained when 50 Hz is identified, and the second constant value L60 is obtained when 60 Hz is identified.

  In the control constant storage memory 141 in the power supply phase calculation unit 14, either the first constant value L50 or the second constant value L60 is given as an integration constant. When the magnitude of the first constant value L50 is “1”, the magnitude of the second constant value L60 is “1.2” reflecting the frequency ratio (60/50).

  The integration unit 142 in the power supply phase calculation unit 14 adds integration constants at regular time intervals Δt. In the case of 50 Hz, when the fixed time Δt is 0.1 ms, for example, the added value (integrated value) increases by “1”. Therefore, a sine waveform is generated by associating the magnitude “1” with the electrical angle “1.8 degrees”. As a result, in the case of 50 Hz, one cycle is 20 ms, and a sinusoidal wave system of 0 to 360 degrees is obtained by performing 200 integrations at a time interval Δt of 0.1 ms.

  On the other hand, in the case of 60 Hz, the magnitude of the added value (integrated value) increases by “1.2”, so that sine waves with 1.8 * 1.2 = 2.16 degrees intervals for each time interval Δt. A system will be obtained. As a result, in the case of 60 Hz, one cycle is 16.7 ms, and a sine wave system of 0 to 360 degrees is obtained by integration of 167 times at a time interval Δt of 0.1 ms. This means that a sine wave system of 50 Hz and 60 Hz was obtained only by changing the magnitude of the addition value to be added while the addition period of the integration unit 142 is fixed.

  FIG. 7 is a diagram showing, as means, a procedure when the above-described series of processing is processed by software using a CPU or the like. According to this figure, the first means for detecting the zero cross point of the AC voltage waveform to generate a rectangular signal, the first means for identifying whether the AC power supply frequency is 50 Hz or 60 Hz by measuring the rectangular width of the rectangular signal. Second means, third means for giving a first constant value at 50 Hz and a second constant value at 60 Hz, adding a constant value at regular time intervals within a rectangular width period, and adding the value The fourth means for generating a sine waveform corresponding to the above is provided, and a series of procedures by these means is sequentially executed.

  According to the device of the present invention described above, frequency switching between 50 Hz and 60 Hz can be reliably executed with a simple device configuration.

1: Commercial power supply 2: Filter reactor 3: Converter 4: Capacitor 5: Inverter 6: Hoisting machine 7: Sheave 8: Car 9: Counterweight 10: Voltage detection unit 12: Current detection unit 13: Power supply phase detection unit 14 : Power supply phase calculation unit 15: DC voltage control unit 16: current control unit 17: PWM control circuit 141: control constant storage memory 142: integration unit 143: phase sequence detection circuit 144: rectangularization circuit 145: frequency identification unit 146: timer Part

Claims (6)

In order to perform power conversion by a power converter, a PWM converter device that converts an alternating current into a d-axis current and a q-axis current to perform current control and uses an alternating current power supply phase for the conversion,
First means for detecting a zero-crossing point of the AC voltage waveform to generate a rectangular signal; second means for identifying whether the power frequency of the AC power supply is 50 Hz or 60 Hz by measuring the rectangular width of the rectangular signal; Third means for giving a first constant value at 50 Hz and a second constant value at 60 Hz, and adding the constant value at regular time intervals within the rectangular width period. A PWM converter device comprising fourth means for generating a sine waveform corresponding to the above. The PWM converter device according to claim 1,
The second constant value of the third means has a ratio of 60/50 with respect to the first constant value. The PWM converter device according to claim 1 or 2,
The PWM converter device characterized in that the second means has a function of identifying that the power supply frequency is an abnormal frequency other than 50 Hz or 60 Hz. A car, a counterweight connected to the car via a rope, a hoisting machine that drives the car, and a power converter that converts electric power of the power system to the hoisting machine and drives it In order to perform power conversion by the power converter, an AC current is converted into d-axis and q-axis current for current control, and an elevator drive control apparatus that uses an AC power supply phase for the conversion There,
First means for detecting a zero-crossing point of the AC voltage waveform to generate a rectangular signal; second means for identifying whether the power frequency of the AC power supply is 50 Hz or 60 Hz by measuring the rectangular width of the rectangular signal; Third means for giving a first constant value at 50 Hz and a second constant value at 60 Hz, and adding the constant value at regular time intervals within the rectangular width period. An elevator drive control device comprising a fourth means for generating a sine waveform corresponding to the above. The elevator drive control device according to claim 4,
The identification of the frequency by the second means does not operate while the elevator is running, and operates while the elevator is stopped. The elevator drive control device according to claim 4 or 5,
The second constant value of the third means is a ratio having a ratio of 60/50 to the first constant value.

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