JP2012023921A - Electric power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable precise calculation of an input power amount by accurately obtaining an instantaneous value of an input voltage of a converter without adding a hardware part.SOLUTION: An electric power converter includes at least a converter 5 for converting an AC voltage into a DC voltage and a converter control section 110 for generating a driving pulse of switching elements 51-54 by PMW control so as to control the DC voltage to be constant and maintain a power factor of the converter 5 equal to one. The converter control section 110 includes a converter control software section 111 for calculating a fundamental wave input voltage of the converter 5 as a modulated wave to perform PWM control; voltage conversion means CONfor converting the fundamental wave input voltage into a voltage instantaneous value; electric current conversion means CONfor converting an input electric current into an electric current instantaneous value; multiplication means MPfor multiplying both the instantaneous values; and power running/regenerating electric power integration means INTand INTfor calculating the input electric power of the converter 5 by accumulating the instantaneous electric power which is the output.

Description

  The present invention relates to a power conversion device including at least a converter and a control unit thereof, and more specifically, for example, is applied to an AC electric vehicle fed from a high-voltage single-phase AC overhead line and connected to a secondary side of a main transformer. The present invention relates to a converter input power amount calculation technique in a converter / inverter system including a converter connected to a DC side of the converter and an inverter that supplies three-phase AC power of variable voltage / variable frequency to a vehicle drive induction motor Is.

FIG. 2 is a configuration diagram showing a conventional technique of a converter / inverter system for an AC electric vehicle, which is described in, for example, Patent Document 1 and Non-Patent Document 1.
This prior art controls the AC side voltage of the converter to two voltage levels by pulse width modulation (PWM) control, and is known as a so-called two-level converter / inverter system.

In FIG. 2, vehicle driving power is supplied from a single-phase AC overhead line to the primary winding 21 of the main transformer 2 through the pantograph 1 and returned via the wheels 3 and rails. The main transformer 2 converts the high primary voltage V ₁ supplied to the primary winding 21 into the secondary voltage V ₂ and the tertiary that are suitable for the load by the secondary winding 22 and the tertiary winding 23. each stepped down to the voltage _{V 3.}

Converter 5, the input secondary voltage V ₂ into a DC voltage E _d by on-off operation of the semiconductor switching elements 51 to 54 outputs. Capacitor 6 is connected between the DC output terminals (DC intermediate circuit) of converter 5 in order to smooth the ripple voltage included in the output voltage of converter 5.
On the other hand, the inverter 8, a DC voltage E _d that is smoothed into a 3-phase AC power by on-off operation of the switching element by the condenser 6, supplies AC power of variable voltage and variable frequency to induction motor 9 for driving an electric vehicle To do.

The converter control unit 10 includes a converter control software unit 101 and an electric energy calculation software unit 102.
The converter control software unit 101 has a power factor 1 control function and a DC voltage constant control function of the converter 5 as will be described later, and generates and outputs gate drive pulses for the switching elements 51 to 54 of the converter 5 by PWM control. The power amount calculation software unit 102 calculates a power consumption amount (input power amount of the converter 5) of the power conversion device during the power running operation and the regenerative operation, and transmits the power amount to the monitor (transmission) software.

The tertiary voltage V ₃ of the third winding 23, air-conditioning and is supplied as a power supply voltage to the on-vehicle auxiliary machine 11 such as a lighting equipment, the AC voltage detector 12 and the band pass filter 13 3 primary voltage detection value v ₃ is input to the converter control unit 10.
Further, the input current I ₂ of the converter 5 is detected by the AC current detector 4 and input to the converter control unit 10 as the secondary current detection value i ₂ . Voltage E _d of DC intermediate circuit is detected by the DC voltage detector 7 is input to the converter control unit 10 as a DC voltage detection value e _d.

FIG. 3 is a functional block diagram showing an example of a conventionally used power amount calculation method in the power amount calculation software unit 102.
In FIG. 3, “hardware” indicates the AC voltage detector 12 and the band-pass filter 13 for obtaining the tertiary voltage detection value v ₃ in FIG. 2 and the secondary current detection value i _2. This corresponds to the AC current detector 4 for obtaining the above.

Tertiary voltage detection value _{v 3} is input to the power amount calculation software unit 102, it is converted by the secondary voltage converting means 102a to a secondary voltage (instantaneous _{value) V 2e.} Secondary current detection value _{i 2} is the secondary current (instantaneous _value) by the secondary current conversion means 102b is converted into _{I 2e.} The V _2e and _{I 2e} is converted is multiplied by the multiplication unit 102c instantaneous power _{W e.} Power running operation powering the selective contact function PC is turned on, W _e is accumulated by running power accumulating unit 102d, and output as a running power amount WT _P. Further, during regenerative operation Regenerative selected contact function GC is turned on, W _e is accumulated by the regenerative electric power accumulating means 102e, and output as regenerated electric energy WT _G.
These electric power amounts WT _P and WT _G are transmitted to the communication processing unit 103a of the monitor (transmission) software 103 and monitored on the vehicle.

  Next, FIG. 4 is a configuration diagram showing a main transformer and a load circuit for explaining a theory for converting a tertiary voltage of the main transformer 2 into a secondary voltage. The converter / inverter system 200 in FIG. 4 shows the main circuit including the converter 5 and the inverter 8 in FIG. 2 and the converter control unit 10 together, and other components are the same as those in FIG. The code | symbol is attached | subjected.

In FIG. 4, Z ₁ , Z ₂ and Z ₃ are impedances of the primary winding 21, the secondary winding 22 and the tertiary winding 23 of the main transformer 2. Is included. I ₁ , I ₂ and I ₃ are currents flowing through the windings 21, 22 and 23, and V ₁ ′, V ₂ ′ and V ₃ ′ are induced voltages of the windings 21, 22 and 23. V ₁ , V _2, and V ₃ are terminal voltages of the windings 21, 22, and 23, and are referred to as a primary voltage, a secondary voltage, and a tertiary voltage, respectively.

Here, inherently, the amount of power converter inverter system 200 in FIG. 4, must be integrated value of [V ₂ instantaneous value] × [I ₂ instantaneous value] as instantaneous input power values.
However, conventional [V ₂ instantaneous value, approximate value calculation of [I ₂ instantaneous value], as shown in FIG. 3, respectively, third order voltage detection value v ₃ and a secondary current detection value i ₂ Has been done using.

Here, as a method for converting the tertiary voltage V ₃ to the secondary voltage V ₂ , a conversion formula of V ₃ × (V ₂ ′ / V ₃ ′) is generally used. This is an equation that holds only when the load of V ₃ is zero, that is, when I ₃ = 0 and V ₃ = V ₃ ′. However, since the load using the tertiary voltage V ₃ as a power source greatly fluctuates when the in-vehicle auxiliary machine 11 is started or when the vehicle passes through a section, V ₃ = V ₃ ′ is not always satisfied. Furthermore, the secondary voltage _{V 2} will vary by the voltage drop caused by _{Z 2} of _{I 2 (I 2} × _{Z 2),} in the method for converting a conventional tertiary voltage _{V 3} to the secondary voltage _{V 2,} the voltage Variation due to the descent (I ₂ × Z ₂ ) is not considered.
Thus, since the secondary voltage V ₂ varies due to load fluctuation of the main transformer 2 of tertiary winding 23 and secondary winding 22, in the conventional method shown in FIG. 3, the third order voltage V ₃ It cannot be said that the secondary voltage (instantaneous value) V _2e is accurately converted.

On the other hand, as for the secondary current I ₂ , the current detection value i ₂ is obtained with high accuracy by the AC current detector 4 as shown in FIG. 2, and the secondary current (instantaneous value) is obtained by the secondary current conversion means 102b of FIG. ) Since it is converted to I _2e , I _2e = I ₂ is always established.
As described above, as long as the conventional technique shown in FIG. 3 is used, the secondary voltage (instantaneous value) V _2e does not accurately convert the tertiary voltage V _3. The calculation accuracy of was not satisfactory.

Japanese Patent No. 2946106 (page 6, right column, line 46 to page 8, right column, line 20, FIG. 1 to FIG. 3)

“Latest Electric Railway Engineering”, P.60-P.67, The Institute of Electrical Engineers of Japan, Ed.

When calculating the input electric energy of the converter / inverter system 200 according to the prior art shown in FIG. 3, the secondary voltage (instantaneous value) V _2e converted from the tertiary voltage V ₃ matches the true value. How to convert accurately is a problem in improving the power calculation accuracy. To do so, seek instantaneous power _{W e} by the secondary voltage (instantaneous _{value) V 2e} to accurately detect _{[V 2} instantaneous value] × _{[I 2} instantaneous value, may be integrated with the instantaneous power _{W e} This is as described above.

Here, FIG. 5 shows the relationship between the fundamental wave components of the voltage and current on the secondary winding 22 side in FIG. 4 when the converter 5 is controlled with a power factor of 1, and FIG. Is a vector diagram during power running and FIG. 5B is a vector diagram during regeneration (note that the symbol “→” indicating the vector is omitted in the text for convenience). 6 (a) and 6 (b) correspond to FIGS. 5 (a) and 5 (b), respectively, the instantaneous value V _2p and the fundamental voltage V 2 of the input voltage of the converter 5 during power running and regeneration. it is a waveform diagram showing a _2.

5A and 5B, _assuming that the power supply frequency is f _s , ω = 2πf _s , and the secondary winding impedance Z ₂ occupies the main part of the leakage inductance L _z2, so that Z ₂ = L _z2 Approximate. The fundamental wave voltage phase θ of V ₂ is controlled by the converter control software unit 101 of FIG. 2 so that I ₂ and V ₂ ′ are in phase during power running operation and in reverse phase during regenerative operation.

2, the semiconductor switching elements 51 to 54 constituting the converter 5, the modulated drive pulse by a carrier wave of frequency f _c of the fundamental wave voltage V ₂ of the sinusoidal as a modulated wave (PWM pulse) as shown in FIG. 5 Driven. As a result, as shown in FIG. 6, the instantaneous value V _2p of the voltage V ₂ becomes a PWM pulse train voltage whose peak values are E _d and −E _d , and in this case, the fundamental wave of the instantaneous value V _2p is the sine shown in FIG. to match the voltage _{V 2} of wavy.

As described above, converter To inverters improve the calculation accuracy of the input power of the system 200, [V ₂ instantaneous value] × high precision V ₂ instantaneous value integrated value to calculate the [I ₂ instantaneous value] It is necessary to ask for. Actually the voltage waveform V ₂ obtained by attaching the voltage detector to the input side of the converter 5 of FIG. 2, the pulse train voltage, such as the instantaneous values V _2p shown in FIG.

Carrier frequency _{f c} in the case of using the IGBT as the switching element 51 to 54, generally may be raised to the extent 2 [kHz]. In order to accurately detect the instantaneous value V _2p composed of such a high-frequency pulse train voltage, the voltage sampling frequency must be set to several tens of times, that is, about 100 [kHz]. It is not practical because it is a heavy burden on the top.
On the other hand, it is also possible to determine the fundamental wave passed through its output to filter a voltage detector provided to the AC input side of the converter 5, when the carrier frequency f _c is changed, always accurately detect the fundamental wave voltage It is not always done. Moreover, in such an instantaneous voltage detection method, it is necessary to add hardware components such as a voltage detector and a filter.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a power converter that can accurately calculate an instantaneous value of a converter input voltage and calculate an input power amount with high accuracy without adding hardware components.

In order to solve the above problems, an invention according to claim 1 is directed to a converter that converts an AC voltage into a DC voltage by turning on and off a plurality of semiconductor switching elements, to control the DC voltage to be constant, and to control the power factor of the converter A power converter including at least a converter control unit that generates a drive pulse for turning on and off the switching element by PWM control so as to maintain 1;
The converter controller is
Means for calculating a fundamental wave input voltage of the converter as a modulated wave for performing the PWM control;
Voltage conversion means for converting the fundamental wave input voltage into an instantaneous voltage value;
Current conversion means for converting the input current of the converter into an instantaneous current value;
Means for integrating the product of the instantaneous voltage value and the instantaneous current value to calculate the input electric energy of the converter.

The invention according to claim 2 is the power conversion device according to claim 1,
The converter can perform a power running operation and a regenerative operation, and the converter control unit has a function of separating and integrating the power running power amount and the regenerative power amount.

The invention according to claim 3 is the power conversion device according to claim 1 or 2,
The calculation and conversion function in the converter control unit is realized by software.

The invention according to claim 4 is the power conversion device according to any one of claims 1 to 3,
An inverter is connected to the DC side of the converter via a smoothing capacitor.

In the present invention, in order to calculate the input electric energy of the power converter provided with the converter, the instantaneous value of the input voltage of the converter is modulated for PWM control of the converter so that the power factor on the input side becomes 1. Generate based on the wave. Since this modulated wave represents the fundamental wave input voltage of the converter consisting of the PWM pulse train voltage, if an instantaneous value of the converter input voltage is generated from this fundamental wave input voltage, the third order of the main transformer is included therein. Since compensation by the influence of the voltage drop due to the load fluctuation of the winding and the impedance of the secondary winding is also included, the instantaneous voltage value is more accurate.
The instantaneous power is calculated by multiplying the instantaneous value of the input voltage of the converter and the instantaneous value of the input current obtained from the input current detection value, and this is integrated separately during power running and regeneration. The amount of input power can be calculated with high accuracy. In addition, since all these operations can be processed by software, it is not necessary to add hardware parts, and the circuit configuration can be simplified and the apparatus can be downsized.

It is a functional block diagram of the converter control part which concerns on embodiment of this invention. It is a block diagram which shows the prior art of the converter inverter system applied to an alternating current electric vehicle. FIG. 3 is a functional block diagram illustrating an example of a conventionally used power amount calculation method in the power amount calculation software unit of FIG. 2. It is a block diagram which shows the main transformer and load circuit in FIG. FIG. 5 is a vector diagram showing a relationship between fundamental wave components of voltage and current on the secondary winding side in FIG. 4. It is explanatory drawing of the input voltage waveform of a converter.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a functional block diagram of a converter control unit 110 according to an embodiment of the present invention, which replaces the conventional converter control unit 10 shown in FIG.
That is, the converter control software unit 111 in the converter control unit 110 shown in FIG. 1, the main transformer 2 of 3 primary voltage detection value v ₃ and the secondary current detection value i ₂ and the DC voltage detection value e _d and the input Then, drive pulses for the semiconductor switching elements 51 to 54 of the converter 5 are generated and output. The power amount calculation software unit 112 includes an input fundamental wave voltage V _c to be described later is calculated and the secondary current detection value i ₂ is input by the converter control software unit 111, the running power amount WT _P and regeneration The amount of power WT _G is calculated and output. These electric power amounts WT _P and WT _G are transmitted to the outside for monitoring on the vehicle as in FIG.
The function of the power amount calculation software unit 112 is basically the same as that of the power amount calculation software unit 102 of FIG. 3 except for the voltage conversion unit CON _v . The voltage conversion unit CON _v and the secondary current conversion unit CON _i, powering selected contact function PC, a made of regenerative selective contact function GC and running power integrator INT _P.

In the converter control software unit 111 of FIG. 1, in order to control the voltage E _d of the DC intermediate circuit in FIG. 2 to a constant value, a DC voltage command value e _d ^* is input to the adding means AD ₁ and the detected DC voltage value e The deviation from _d is calculated, and the voltage adjusting means AVR adjusts so that this deviation becomes zero ( _ed = _ed ^* ). The output of the voltage adjusting means AVR becomes a converter input current command value of the DC amount I _s ^* .
Tertiary voltage detection value v ₃ of the main transformer 2 is input to the phase detecting section 111a, together with the zero-cross point of the power supply voltage is detected, the supply voltage and in phase via the reference sine wave data 111b sinusoidal signal √ 2sinθ is generated. Here, the zero cross point of the power supply voltage should theoretically be detected from the secondary voltage, but actually, for example, Japanese Patent No. 2509890 (Title of Invention: Pulse Width Modulation Control Method of AC / DC Converter) As shown in FIG. 1, the third voltage is detected from a low voltage.

The multiplying means MP ₁ calculates I _s ^* × √2 sin θ, and outputs a sine wave current command value i _s ^* (= I _s ^* √2 sin θ) in phase with the power supply voltage to the adding means AD ₂ .
The adding means AD ₂ calculates a deviation between the current command value i _s ^* and the secondary current detection value i ₂ of the main transformer 2, and this deviation is zero (i ₂ = i _s ^* , i ₂ = ^{_{i s * = I s * √2sinθ}} ) and so as a current regulating means ACR is by operating adjusting, and outputs a voltage signal _{e c.}

The aforementioned voltage signal _{e c,} 3 primary voltage detection value _{v 3} of the main transformer 2 are added by the adding means AD _3, its output is _{e c0 = e c + v 3} . The e _c0 is scaled by dividing by the DC voltage detection value e _d in divider DV, a converter input fundamental wave voltage V _c. This converter input fundamental wave voltage V _c matches V ₂ in the vector diagram of FIG. 5 described above.
The fundamental wave voltage V _c becomes a modulated wave of the PWM arithmetic means PWM, and a pulse train voltage generated by comparison with the carrier wave is output as a drive pulse for the switching elements 51 to 54 of the converter 5.

From the above description, in order to calculate the integrated value of [V ₂ instantaneous value] × [I ₂ instantaneous value] described above, the instantaneous value of the fundamental wave voltage V _c for PWM control of the converter input voltage V ₂ is [ by using instead of the V ₂ instantaneous value, it can be seen that calculates input power amount more accurately.
That is, in this embodiment, the power amount calculation software unit 112 of FIG. 1, the multiplication unit MP _{0,
[V c} voltage instantaneous value converted _{from: V 2e] × [I 2} (i 2) converted from the current instantaneous _{value: I 2e]} calculated instantaneous power by calculating a running power integrating means the instantaneous power INT _P And the regenerative power integration means INT _G calculates the input power amount by integrating.

In the electric energy calculation software unit 112, the voltage conversion means CON _v converts the fundamental wave voltage V _c into the instantaneous value V _2e of the actual voltage, and the current conversion means CON _i converts the secondary current detection value i ₂ into the actual current value. Convert to instantaneous value I _2e . The functions of the power running selection contact function PC, the regeneration selection contact function GC, the power running power integration means INT _P, and the regenerative power integration means INT _G are the same as in FIG. 3, and the amount of power output from each integration means INT _P and INT _G is The data is transmitted to the monitor (transmission) processing unit and monitored on the vehicle.

  The present invention can be used not only for a so-called converter / inverter type power converter but also for a power converter generally provided with at least a converter and its control unit.

1: Pantograph 2: Main transformer 21: Primary winding 22: Secondary winding 23: Tertiary winding 3: Wheels 4: AC current detector 5: Converters 51-54: Semiconductor switching element 6: Capacitor 7: DC voltage detector 8: Inverter 9: Induction motor 10: Converter control unit 101: Converter control software unit 102: Electric energy calculation software unit 103: Monitor software 103a: Communication processing unit 11: In-vehicle accessory 12: AC voltage detector 13 : Band pass filter 110: Converter control unit 111: Converter control software unit 111 a: Phase detection means 111 b: Reference sine wave data 112: Electric energy calculation software part 200: Converter / inverter system AD ₁ , AD ₂ , AD ₃ : Addition means AVR: Voltage adjusting means ACR: Current adjusting means MP ₀ , MP ₁ : Multiplier Stage DV: Division means PWM: PWM calculation means CON _v : Voltage conversion means CON _i : Current conversion means PC: Power running selection contact function GC: Regenerative selection contact function INT _P : Power running power integration means INT _G : Regenerative power integration means

Claims (4)

A converter that converts an AC voltage into a DC voltage by turning on and off a plurality of semiconductor switching elements, and a PWM control that turns the switching elements on and off so that the DC voltage is controlled to be constant and the power factor of the converter is maintained at 1. In a power converter comprising at least a converter control unit that generates a drive pulse for
The converter controller is
Means for calculating a fundamental wave input voltage of the converter as a modulated wave for performing the PWM control;
Voltage conversion means for converting the fundamental wave input voltage into an instantaneous voltage value;
Current conversion means for converting the input current of the converter into an instantaneous current value;
Means for calculating the input electric energy of the converter by integrating the product of the voltage instantaneous value and the current instantaneous value;
A power conversion device comprising: In the power converter device according to claim 1,
The converter is capable of power running operation and regenerative operation,
The converter control unit is provided with a function of separating and integrating a power running power amount and a regenerative power amount. In the power converter device according to claim 1 or 2,
A power conversion device characterized in that the calculation and conversion functions in the converter control unit are realized by software. In the power converter device according to any one of claims 1 to 3,
An inverter is connected to the DC side of the converter via a smoothing capacitor.

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