JP2565926B2 - Power converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention relates to a power converter having an AC-DC power converter circuit for performing pulse width modulation control.

(Prior Art) Generally, an AC-DC power conversion circuit that performs a high-frequency pulse width modulation method using a self-arc-extinguishing type semiconductor device such as a gate turn-off thyristor (hereinafter referred to as GTO) is used as The GTO switching control is performed at a high frequency more than double to control the output current waveform and phase. In such an AC-DC power conversion circuit, the waveform of the input voltage is modulated with a high frequency, but in order to make the waveform of the input current sinusoidal, a reference sine wave and a high frequency triangular wave that is a modulation wave are compared. Is compared and calculated by the control signal
Switch GTOs in a fixed order. The modulation frequency of this triangular wave (hereinafter referred to as the modulation frequency) is normally an odd multiple of the high power supply frequency, for example 450Hz when the power supply is 50Hz.
Alternatively, it is set to 550 Hz or the like.

An AC electric vehicle equipped with such an AC-DC power conversion circuit has lines with different overhead line power frequencies, for example, 50 Hz and 60 Hz.
When traveling on a line having two applicable frequencies, the control for changing the frequency of the triangular wave used for controlling the AC-DC power conversion circuit is performed by confirming the frequency change inside the vehicle for harmonic current control. Be done. This change control uses a modulation frequency of 550Hz (50Hz if the overhead power line is 50Hz).
× 11) and the modulation frequency is 66 when the overhead power line is 60 Hz.
It is controlled to 0Hz (60Hz x 11).

(Problems to be Solved by the Invention) In the conventional device, as the modulation frequency is decreased, the AC-
The peak current in the same load of the switching elements forming the DC power conversion circuit tends to increase. Also,
Since the current rating of the switching element is determined in consideration of the peak current of the element, the switching element rating of the AC-DC power conversion circuit is determined by the peak current when the modulation frequency is the lowest. On the other hand, the power loss in the peripheral circuit of the switching element, such as the gate circuit and the snubber circuit, increases as the modulation frequency increases.

In this way, when traveling in sections with different commercial frequencies, the modulation frequency is simply proportional to the power supply frequency to match the current rating of the switching element to the case where the power supply frequency is low, while the thermal capacity of the peripheral circuits It is adapted for high frequencies. For this reason, if the circuit is designed in consideration of the current rating and the thermal capacity of the peripheral circuits, various circuits and the like must be provided, and the device may become large.

The present invention has been made in view of the above, and an object thereof is to provide a power conversion device that efficiently supplies power without complicating the device.

[Configuration of the Invention] (Means for Solving Problems) In order to achieve the above object, the present invention detects the frequency of AC power input to a power conversion circuit that converts AC power into DC power, A modulation frequency output circuit that switches and outputs each modulation frequency set according to the detected frequency, a triangular wave generation circuit that generates a triangular wave of the modulation frequency output from this modulation frequency output circuit, and a power conversion circuit A gate control circuit that compares the reference power corresponding to the input / output power with the triangular wave generated by the triangular wave generation circuit to generate an operation signal of the power conversion circuit and output the operation signal to the power conversion circuit. And the modulation frequency is set to a different positive odd multiple depending on the detectable frequency, and the positive odd number reduces the frequency difference between the respective modulation frequencies. And it said that there was Unishi.

(Operation) In the power conversion device having the above configuration, the frequency of the AC power input to the power conversion circuit that converts the AC power into the DC power is detected, and the modulation frequency is set according to the detected frequency. To switch and output. This modulation frequency is set to a different positive odd multiple depending on the frequency of the AC power that can be detected, and a positive odd number is designed to reduce the frequency difference between the modulation frequencies so that power can be efficiently supplied. be able to.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing an embodiment of the power converter of the present invention. In this power conversion device, a modulation frequency output circuit 3 is connected to an input side of an AC-DC power conversion circuit 1 for inputting AC power and converting AC into DC power, and an output side of the modulation frequency output circuit 3 is further connected to the modulation frequency output circuit 3. The triangular wave generation circuit 5 is connected. On the other hand, the reference current pattern generation circuit 7 is connected to the output side of the AC-DC power conversion circuit 1.
The comparison circuit 9 connected to the triangular wave generation circuit 5 and the reference current pattern generation circuit 7 compares and operates the signals input from the triangular wave generation circuit 5 and the reference current pattern generation circuit 7, and outputs a control signal to the gate control circuit 11. Output. The gate control circuit 11 performs switching control of a GTO (gate turn-off thyristor) that constitutes the AC-DC power conversion circuit 1 according to the control signal input from the comparison circuit 9.

FIG. 2 is a block diagram showing the control of the power converter of the present invention described in FIG. The current collector (pantograph) 13 supplies AC power supplied from an overhead wire (not shown) to the primary winding side of the main transformer 15 and grounds to the wheels W of the electric vehicle. The AC-DC power conversion circuit 1 is connected to the secondary winding side of the main transformer 15 via a reactor 12. An inverter circuit 25 and an output voltage detector are provided on the output side of the AC-DC power conversion circuit 1 via a capacitor 23.
27 is connected, and an AC main motor 29 is connected to the output side of the inverter circuit 25.

The AC-DC power conversion circuit 1 is further connected in the same manner with a GTO (gate turn-off thyristor) 31a and a diode 31b connected in anti-parallel as one arm.
A bridge circuit is configured by O31c, 31e, 31g and diodes 31d, 31f, 31h. The inverter circuit 25 is also GT
O33a, 33c, 33e, 33g, 33i, 33k and diodes 33b, 33d, 33f,
A bridge circuit is composed of 33h, 33j, and 33l. In the inverter circuit 25, the gate control signal is input from the inverter control circuit 35 to the GTO in the inverter circuit 25 to control the voltage value and frequency of the output power.

The modulation frequency output circuit 3 has a 50 Hz detection circuit 37, a 60 Hz detection circuit 39, and a data select circuit 51.
The 50 Hz detection circuit 37 and the 60 Hz detection circuit 39 are connected to the secondary winding side of the transformer 15. 50Hz detection circuit 37
The detection signal is preset to 50 Hz, and a detection signal is output to the data select circuit 41 when the frequency supplied from the transformer 15 detects 50 Hz. Further, the 60 Hz detection circuit 39 outputs a detection signal to the data select circuit 41 when the frequency detection value is preset to 60 Hz and the frequency supplied from the transformer 15 is 60 Hz. The data select circuit 41 is connected to the output side of the 50 Hz detection circuit 37 and the 60 Hz detection circuit 39. Data select circuit 41
When the detection signal is input from the 50Hz detection circuit 37,
When a detection signal is input from the 60 Hz detection circuit 39, 550 Hz, which is 11 times Hz, is output to the triangular wave generation circuit 5 with 540 Hz, which is 9 times the frequency 60 Hz, as a command value. Triangle wave generation circuit 5
Is connected to the output side of the modulation frequency output circuit 3, generates a triangular wave having a frequency that matches the input modulation frequency command value, and outputs the triangular wave to the comparison circuit 9.

The reference current pattern generation circuit 7 is a voltage detector 43, an arithmetic unit
45, an amplifier 47, a multiplier 49, and a calculator 51. The deviation between the voltage value detected by the voltage detector 43 connected to the secondary winding side of the transformer 15 and the reference voltage value REF provided inside the circuit is calculated by the calculator 45 and the amplifier 47
Is amplified by and output to the multiplier 49. The multiplier 49 is a sine wave-shaped signal obtained by multiplying the sinusoidal AC voltage value from the voltage detector 43 provided for detecting the voltage on the input side of the AC-DC power conversion circuit 1 and the output value from the amplifier 49. The reference current pattern of is output to the calculator 51. The calculator 51 calculates the difference between the reference current pattern from the multiplier 49 and the detection value of the current detector 21 for detecting the current on the input side of the AC-DC conversion circuit 1, and outputs the difference to the comparison circuit 9.

The comparison circuit 9 compares and calculates the reference current pattern input from the calculator 51 and the triangular wave input from the triangular wave generation circuit 5, and outputs a control signal based on the comparison result.
Output to 11.

The gate control circuit 11 controls the DC output voltage of the AC-DC power conversion circuit 1 to a constant value and at the same time makes the waveform of the AC input current sinusoidal and eliminates the phase difference between the input voltage and the current GTO31a, 31c, 31c. , 31g to output a gate signal.

 Next, the operation of this embodiment will be described.

First, an AC voltage is supplied from a transformer 15 to an AC-DC power conversion circuit 1 from a pantograph 13 connected to an overhead wire (not shown). When the AC power is supplied to the AC-DC power conversion circuit 1, the AC detected by the voltage detector 27-
The deviation between the detected value of the output voltage of the DC power conversion circuit 1 and the reference value REF is calculated by the calculator 45, and the output value is amplified.
Amplified by 47. The output value from the amplifier 47 and the voltage detector provided on the input side of the AC-DC power conversion circuit 1.
The sinusoidal AC voltage value detected by 43 is multiplied by the multiplier 49.
A reference current pattern having a sinusoidal waveform that is multiplied by is output to the calculator 51. The deviation between this reference current pattern and the AC current detected by the current detector 21 provided on the input side of the AC-DC power conversion circuit 1 is calculated by the calculator 51. The calculated deviation is input to the comparison circuit 9.

Here, when the frequency of the AC voltage of the electric vehicle is 50 Hz, the data selection circuit 41 outputs 550 Hz (= 50 × 11 Hz) as a specified value by operating the 50 Hz detection circuit 37 and outputting a detection signal. . In response to the input of the designated value, the triangular wave generation circuit 5 generates a 550 Hz triangular wave. That is,
When the frequency of the AC input is 50Hz, the comparison circuit 9 has 550Hz.
The triangular wave of is input. The frequency of the AC voltage is 60Hz
In the case of, the 60 Hz detection circuit 39 operates and the data select circuit
Since 41 outputs 540 Hz (= 60 × 9 Hz) as a command value,
The triangular wave generation circuit 5 generates a 540 Hz triangular wave, and the 540 Hz triangular wave is input to the comparison circuit 9. In addition, the modulation frequency at this time is 9 times the frequency of 50Hz when 50Hz is input.
If z is selected and 60 Hz is input, 420 Hz, which is seven times the frequency of 60 Hz, can be selected.

Then, the comparison circuit 9 inputs the output value of the calculator 51 and the output signal of the triangular wave generation circuit 5, performs comparison calculation, and outputs a control signal to the gate control circuit 11. The gate control circuit 11 receives the output value from the comparison circuit 9 and outputs a gate signal to the GTOs 31a, 31c, 31e, 31g of the AC-DC power conversion circuit 1 based on this output value.

Thus, even if the frequency of the alternating current supplied to the AC-DC power conversion circuit 1 changes, the modulation frequency is generated in response to the changed frequency. Therefore, the current rating of the main circuit element and the snubber circuit, the gate circuit The heat capacity of can be effectively used.

Moreover, the present embodiment is not limited to the power conversion of the electric railway, but can be applied to the power conversion of various devices.

[Advantages of the Invention] As described above, according to the present invention, the frequency of the AC power input to the power conversion circuit that converts the AC power into the DC power is detected, and each is set according to the detected frequency. The selected modulation frequency is switched and output. This modulation frequency is set to a different positive odd multiple depending on the frequency of detectable AC power, and a positive odd number reduces the frequency difference between the respective modulation frequencies, which complicates the device. Power can be supplied efficiently.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a power converter of the present invention, and FIG. 2 is a block diagram showing control of the power converter of the present invention. 1 …… AC-DC power conversion circuit 5 …… Triangular wave generation circuit 7 …… Reference current pattern generation circuit 9 …… Comparison circuit 11 …… Gate control circuit 37 …… 50Hz detection circuit 39 …… 60Hz detection circuit 41 …… Data Select circuit

Claims (1)

(57) [Claims] 1. A modulation frequency output circuit for detecting a frequency of AC power input to a power conversion circuit for converting AC power into DC power, and switching and outputting a modulation frequency set in accordance with the detected frequency. A triangular wave generating circuit that generates a triangular wave of the modulation frequency output from the modulation frequency output circuit, and a reference power corresponding to the input / output power of the power conversion circuit and the triangular wave generated by the triangular wave generating circuit are compared. A gate control circuit that generates an operation signal of the power conversion circuit and outputs the operation signal to the power conversion circuit, wherein the modulation frequency is a positive odd multiple different depending on the detectable frequency. The power conversion device is set, and the positive odd number reduces the frequency difference between the modulation frequencies.