JP5121895B2 - PWM inverter control device - Google Patents

Description

  The present invention relates to a PWM inverter control device, and more particularly, to a carrier frequency spreading method for reducing electromagnetic noise generated at the start of a railway vehicle without increasing heat generation of a main circuit element such as an IGBT.

  In a control device for a PWM inverter in a railway vehicle, the inverter device is driven by setting the frequency of a carrier wave (hereinafter referred to as a carrier) to about several hundreds to several kHz due to the problem of heat generation of a main circuit element.

  This frequency band is included in the human audible frequency band, so when the vehicle starts to move, it is wiped out by rolling noise. Especially when the vehicle starts up, certain electromagnetic noise generated from the electric motor becomes noise and gives unpleasant feeling. Yes.

  For this reason, research on so-called carrier diffusion control, in which carrier frequency is modulated to generate white noise, has been conventionally conducted, and the following method has been proposed as an example.

  In one described system, modulation is applied to the frequency f by a function of 1 / f so as not to cause discomfort when a human hears (see, for example, Patent Document 1).

  In another method, the half-cycle of the carrier is modulated so as to keep the current control period constant, so that the white noise of the electromagnetic sound and the current control are compatible (for example, see Patent Document 2).

  Also, in recent railway vehicles, so-called all-electric brake stop control is being introduced that makes regenerative braking effective up to extremely low speeds. When this control is introduced, the regenerative brake is operated up to the vicinity of the inverter frequency Fi≈0 [Hz], so that heat generation of the main circuit element becomes a problem. Therefore, control is performed to reduce the carrier frequency in a region where the speed is low during regenerative braking.

JP-A-6-14557 JP 2000-184729 A

  In a railway vehicle control device, in order to prevent destruction of a main circuit element such as an IGBT due to heat generation, an element loss estimation calculation for estimating the temperature of the element by software and performing protection is performed. In this calculation, it is necessary to input the carrier frequency with high accuracy in addition to analog quantities such as voltage and current that change every moment. However, in the above prior art, although the noise reduction by the carrier frequency modulation is described, since the element loss estimation calculation error due to the variation of the average carrier frequency within the predetermined range is not taken into consideration, the protection by the heat generation is not considered. There is a risk of incorrect timing and device destruction.

  Also, if carrier diffusion control is executed with a low carrier frequency, such as during all electric brake stop control, the carrier frequency will be further reduced, resulting in a large current ripple. There is a risk of deterioration.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a PWM inverter control device provided with carrier diffusion control means for preventing an increase in loss of a main circuit element of an inverter device, minimizing an element loss estimation calculation error, and reducing noise due to electromagnetic noise. It is to provide.

  In order to achieve the above object, in the control apparatus for a PEM inverter according to the present invention, the average value of the spreading frequencies ± ΔFc added to the basic carrier frequency Fc0 is set to approximately zero.

  In addition, the constant table data as the average value of the diffusion frequency ± ΔFc added to the basic carrier frequency Fc0 is approximately zero so as to eliminate a specific component included in the electromagnetic sound as much as possible. And it was composed of randomly selected data.

  According to the present invention, an increase in element loss can be prevented and the carrier frequency used for the element loss estimation calculation can always be set to the basic carrier frequency Fc0, so that the calculation error can be minimized.

  In addition, according to the present invention, electromagnetic noise can be made white noise, so that noise can be reduced.

The figure which shows embodiment of this invention. The figure which shows the structure of the 1st Example of this invention. The figure which shows the example of data of the constant table of this invention. The figure which shows the structure of the 2nd Example of this invention. The figure which shows the example of application of the 2nd Example of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of a general PWM inverter device for a DC train to which the present invention is applied. The DC power of the overhead line is connected to a reactor 6 (hereinafter referred to as a filter reactor) and a capacitor 7 through a pantograph 1, a high-speed circuit breaker 2, a current breaker 3, and a current breaker 4 resistor 5 connected in parallel. DC power input to a filter circuit (hereinafter referred to as a filter capacitor) and smoothed by the filter circuit is supplied to the inverter device 8.

  The inverter device 8 converts the DC power into variable voltage, variable frequency three-phase AC power based on the PWM signal SPWM output from the inverter control device 12, and supplies it to the induction motor 10.

  CTs 9 a, 9 b, 9 c are respectively inserted into three-phase wirings connecting the inverter device 8 and the induction motor 10, and detect the respective phase currents Iu, Iv, Iw flowing through the induction motor 10.

  The speed signal generator 11 is attached to the rotating shaft of the induction motor 10 and outputs a speed signal SPG corresponding to the number of rotations.

  The inverter control device 12 takes in the voltage Ecf of the filter capacitor 7 and the phase currents Iu, Iv, Iw of the induction motor 10 output from the current detectors 9a, 9b, 9c and the information of the speed signal generator 11 into this. Based on this, the PWM signal SPWM is generated.

  Hereinafter, the schematic configuration of the inverter control device 12 according to the present invention will be described with reference to FIG. The inverter control device 12 includes a PWM control calculation unit 122, a carrier frequency calculation unit 123, an element loss estimation calculation unit 124, and a speed signal conversion unit 125 with a vector control calculation unit 121 as a center.

  The speed signal converter 125 converts the speed signal SPG output from the speed signal generator 11 into the rotor frequency Fr of the induction motor 10. A general induction motor in a railway vehicle is a four-pole motor, and the speed signal generator outputs a signal of 60 pulses per rotation of the rotor of the induction motor. The relationship of the following formula (1) is established.

  The vector control calculation unit 121 takes in the filter capacitor voltage Ecf and the phase currents Iu, Iv, Iw inputted as analog signals through analog / digital conversion processing, and converts them into values convenient for digital calculation. The calculation is executed based on the phase currents Iu, Iv, Iw and the rotor frequency Fr, and the inverter frequency Fi, the voltage command Vc, and the deflection angle δ are output.

  The carrier frequency calculation unit 123 outputs a carrier frequency Fc subjected to spreading control for generating the PWM signal SPWM as will be described later.

  The PWM control calculation unit 122 generates a PWM signal SPWM for generating AC power having a predetermined voltage and frequency based on the inverter frequency Fi, the voltage command Vc, the deflection angle δ, and the carrier frequency Fc. Thereby, the induction motor 10 is driven via the inverter device 8.

  The element loss estimation calculation unit 124 calculates the loss of the main circuit element based on the filter capacitor voltage Ecf output from the vector control calculation unit 121, the phase currents Iu, Iv, Iw, and the carrier frequency Fc, and the heat generation by this is determined in advance. When it is estimated that the value exceeds the first value, first, the carrier frequency lowering signal SFC is output to the carrier frequency calculating unit 123, and when it is further determined to be dangerous, the gate stop signal SGS is output to the PWM control calculating unit 122. Output.

  Next, the carrier frequency calculation unit 123 of the present invention will be described in detail. FIG. 2 shows the configuration of the carrier frequency calculation unit 123 of this embodiment. The carrier frequency calculation unit 123 includes a constant 1231, a constant 1232, a constant 1233, a switch 1234, a table 1235, a multiplier 1236, and an adder 1237.

  The constant 1231 is a carrier frequency pattern Fcp that changes according to the voltage command Vc during normal running, the constant 1232 is the carrier frequency pattern Fch that changes according to the voltage command Vc when heat generation is abnormal, and the constant 1233 is the carrier frequency variation ΔFc. , A preset constant. The table 1235 is a table that outputs a coefficient k1 of −1.0 to +1.0, and the coefficient k1 is updated every time the carrier frequency calculation unit 123 is activated.

  An example of table data stored in the table 1235 is shown in FIG. The table data is composed of 1024 pieces of data that are discontinuous and without regularity, and the average value of all data is selected to be ≈0. As a result, the average value of the carrier frequency Fc when the table data makes a round becomes ≈Fc0, and no increase in heat generated by changing the carrier frequency occurs.

  Hereinafter, the operation of the carrier frequency calculation unit 123 will be described. First, during normal driving, the carrier frequency pattern Fcp of the constant 1231 is selected by the switch 1234, and the basic carrier frequency Fc0 corresponding to the voltage command Vc is output. On the other hand, the coefficient k1 obtained from the table 1235 and the carrier frequency variation ΔFc of the constant 1233 are multiplied by the multiplier 1236 to obtain the final carrier frequency variation ΔFc ′, and the carrier frequency variation ΔFc ′ and the basic carrier frequency Fc0 are obtained. Addition is performed by the adder 1237 and output as the carrier frequency Fc. This carrier frequency Fc calculation procedure is expressed by the following equation (2).

  Next, when the heat generation is abnormal, the carrier loss lowering signal SFC is output from the element loss estimation calculation unit 124, and accordingly, the switch 1234 is switched, and the carrier frequency pattern Fch of the constant 1232 is selected. A basic carrier frequency Fc0 corresponding to the voltage command Vc is output. The following processing is the same as that in the normal running. Here, the carrier frequency patterns Fcp and Fch are normally set to satisfy Fcp ≧ Fch.

  The induction motor 10 is driven via the inverter device 8 by the PWM signal SPWM generated based on the carrier frequency Fc thus obtained.

  As described above, according to the present embodiment, since the average value of the carrier frequency Fc becomes ≈Fc0, it is possible to prevent an increase in element loss and minimize an operation error in the element loss estimation calculation. Further, since the electromagnetic noise can be made white noise, noise can be reduced.

  FIG. 4 shows the configuration of the carrier frequency calculation unit 123 according to another embodiment of the present invention. In the figure, the same symbols as those in FIG. This embodiment is characterized in that a constant 1238, a power running / regeneration determination process 1239, a process 123A, a second switch 123B, and a second multiplier 123C are loaded.

  In FIG. 4, a constant 1238 is a third carrier frequency pattern Fcb that varies according to the voltage command Vc, and is a preset constant. The power running / regeneration determination process 1239 is a power running / regeneration determination process, and outputs a switching signal SB during regenerative braking. The process 123A performs an operation of outputting a coefficient k2 in which the basic carrier frequency Fc0 'continuously changes from 0.0 to 1.0 between Fc1 and Fc2.

  Hereinafter, the operation of the carrier frequency calculation unit 123 will be described with respect to parts different from those in FIG. First, at the time of power running, the basic carrier frequency Fc0 is selected by the switch 1234, and the final basic carrier frequency Fc0 'corresponding to the voltage command Vc is output. On the other hand, the coefficient k2 obtained from the processing 123A according to the final basic carrier frequency Fc0 ′ and the coefficient k1 obtained from the table 1235 are multiplied by the multiplier 123C to obtain the coefficient k3. Further, the coefficient k3 and the carrier frequency of the constant 1233 are obtained. A final carrier frequency variation ΔFc ′ obtained by multiplying the variation ΔFc by the multiplier 1236 is obtained. The carrier frequency variation Fc ′ and the basic carrier frequency Fc0 ′ are added by the adder 1237 and output as the carrier frequency Fc. This carrier frequency Fc calculation procedure is expressed by the following equation (3).

  Next, since the brake signal SB is output from the power running / regeneration determination processing 1239 during regenerative braking, the switch 123B is switched accordingly, and the carrier frequency pattern FcB of the constant 1238 is selected, and the voltage command Vc is similar to the above. The basic carrier frequency Fc0 ′ corresponding to is output. The following processing is the same as in the above power running. Here, the carrier frequency patterns Fcp, Fch, Fcb are normally set so that Fcp ≧ Fch ≧ Fcb.

  FIG. 5 shows an example of carrier frequency characteristics to which this embodiment is applied. The figure shows the pulse mode in the bipolar modulation mode when the voltage command Vc is 0 ≧ Vc ≧ Vc2, the overmodulation mode in which the carrier frequency is changed to the maximum value Fcmax in the range of Vc2 <Vc <100%, and the one pulse mode thereafter. In this case, the carrier frequency patterns Fcp and Fch at the time of power running are equal, and the carrier frequency pattern Fcb at the time of regenerative braking is gradually lowered in a range where the voltage command Vc is 0% ≦ Vc ≦ Vc1.

  In this embodiment, since carrier diffusion control is applied within the shaded area shown in the figure, even if the basic carrier frequency Fc0 'decreases to Fc1 during regenerative braking, current control accuracy is not adversely affected.

DESCRIPTION OF SYMBOLS 1 DC overhead wire 2 High-speed circuit breaker 3, 5 Current breaker 4 Charging resistor 6 Filter reactor 7 Filter capacitor 8 Inverter device 9a, 9b, 9c Current detector 10 Induction motor 11 Speed signal generator 12 Inverter control device 121 Vector control calculation Unit 122 PWM control calculation unit 123 Carrier frequency calculation unit 124 Element loss estimation calculation unit 125 Speed signal conversion unit 1231, 1232, 1238 Carrier frequency pattern constant 1233 Carrier frequency fluctuation constant 1234, 123B switch 1235 constant table 1236, 123C multiplier 1237 Adder 1239 Power running / regenerative discrimination process 123A Coefficient k2 calculation process

Claims (1)

According to the magnitude of the voltage command, there are provided PWM pulse generating means for switching each operation mode of the bipolar modulation mode, the over modulation mode, and the 1 pulse mode, and generating a PWM pulse corresponding to the operation mode according to the modulation wave and the carrier wave, In the PWM inverter control device for controlling the inverter device for driving the induction motor by the PWM pulse,
Carrier frequency spreading means for spreading the fundamental frequency of the carrier used in the PWM pulse generating means,
The carrier frequency spreading means operates in the range of the bipolar modulation mode, and spreads the frequency of the carrier so that the average value of the spread carrier frequency becomes the fundamental frequency in a predetermined range. PWM inverter control device.

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