JP4391339B2 - Auxiliary power supply for vehicle - Google Patents

Description

  The present invention employs computer control for equipment such as a travel control device, brake control device, air conditioning control device, control transmission device, broadcasting device, lighting device, door control device, etc. in a railway vehicle, and supply of control power and power thereof. The present invention relates to an auxiliary power supply used as a power source.

  In the conventional auxiliary power supply for a vehicle, the intermediate link DC voltage is generated by a single-phase mixed bridge rectifier circuit using a thyristor with the tertiary winding output of the main transformer as an input. Using this as an input, a three-phase PWM (Pulse Width Modulation) inverter using an IGBT (Insulated Gate Bipolar Transistor) is operated to output a three-phase alternating current of 60 Hz via an output transformer and supplied to the main line (for example, Non-Patent Document 1).

A case will be described in which a conventional auxiliary power supply for a vehicle is used in an AC 25 kV AC overhead line system employed in a Shinkansen train or the like.
First, the AC 25 kV voltage collected by the pantograph from the AC overhead wire is supplied to the main transformer via the circuit breaker, and is stepped down to a low voltage, for example, AC 400 V by the main transformer. Next, this single-phase AC 400 V voltage is converted into, for example, DC 330 V by the single-phase mixed bridge rectifier circuit. The DC 330V voltage is converted into a three-phase AC, for example, AC 400V, a three-phase voltage by a three-phase PWM inverter, an output transformer and an AC filter capacitor, and supplied to a load.

In this conventional vehicular auxiliary power supply device, a single-phase mixed bridge rectifier circuit is interposed between the input AC and the DC link part, and the DC potential fluctuates when switching. An insulation transformer (leakage transformer) with a built-in reactor function is installed.
Then, using a voltage sensor (usually PT: Potential Transformer is used), the output voltage AC400V is converted into a control circuit level voltage (for example, AC4V), and output to the adder as output voltage feedback. The voltage command generation circuit generates and outputs a sine wave voltage waveform to be output by the three-phase PWM inverter. The output of the voltage command generation circuit is amplified by a voltage controller after taking the difference from the output voltage feedback from the voltage sensor by an adder. The output of the voltage controller is compared with the output of the triangular wave carrier generation circuit by a comparator, and is output to the gate drive circuit as a PWM modulation signal. The three-phase PWM inverter is driven by the gate drive circuit based on the PWM modulation signal, and its output voltage is controlled.

Yoshio Hosoda, “Latest Technology and Trends of Auxiliary Power Supplies for Vehicles”, 1997 Annual Conference of the Institute of Electrical Engineers of Japan 13-13-S. 13-16

  In the conventional auxiliary power supply for vehicles, the DC component of the output voltage of the three-phase inverter is cut off while passing through the insulation transformer (leakage transformer) and the voltage sensor (PT). Therefore, for example, even if a slight DC component is generated on the primary side of the insulation transformer and becomes a demagnetization (DC excitation) state, it cannot be detected by the voltage sensor, and the demagnetization cannot be suppressed. Therefore, in the case of a transformer that is weak against bias, there is a problem that a large primary current flows and protection stops.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a vehicle auxiliary power supply device that can reliably detect a DC component of an inverter output and can prevent DC excitation.

  The auxiliary power supply for a vehicle according to the present invention includes a main transformer that transforms and outputs an AC input, a PWM converter that generates and outputs a DC link voltage using the output of the main transformer as an input, and an output of the PWM converter. , And a three-phase inverter circuit that generates and outputs a three-phase alternating current, a voltage sensor that detects output voltage feedback for controlling the output voltage of the three-phase inverter circuit, and the output voltage feedback, And an inverter circuit control unit that controls an output voltage of the three-phase inverter circuit, wherein the PWM converter has a filter capacitor connected in series between the output terminals, and is connected in series. Further, the midpoint of the filter capacitor is grounded, and the voltage sensor outputs the output of the three-phase inverter circuit. The pressure by the resistance partial pressure in which is configured to detect the output voltage feedback.

  According to the present invention, since the midpoint of the filter capacitor connected in series of the PWM converter is grounded, the potential of the DC link voltage can be fixed, and the conventionally required isolation transformer between the load and the load is unnecessary. The DC component of the output voltage of the three-phase inverter circuit is not cut off. Moreover, since the voltage sensor is configured to detect the output voltage feedback by resistance voltage dividing the output voltage of the three-phase inverter circuit, the DC component of the output voltage generated in the three-phase inverter circuit can be detected reliably. it can. Therefore, even when the transformer can be suppressed and the transformer is weak against the bias, it is prevented in advance that a large primary current flows and the protection is stopped.

FIG. 1 is a circuit diagram showing an auxiliary power supply for a vehicle according to an embodiment of the present invention.
In FIG. 1, the auxiliary power supply for a vehicle includes a pantograph 1 that collects current from an AC 25 kV AC overhead line, a circuit breaker 2 that opens and closes the entire high-voltage circuit, a main transformer 3 that converts an AC 25 kV voltage to a low voltage of, for example, AC 400 V, and an auxiliary power supply A contactor 4 that opens and closes the circuit of the device, a first AC reactor 5 that suppresses input harmonic current, a PWM converter 6 that generates and outputs a DC link voltage from the input AC, and generates a three-phase constant voltage AC from the DC, The output voltage is calculated from the output voltage of the three-phase inverter circuit 7 to output, the second AC reactor 8 and the AC filter capacitor 9 to remove the harmonic component of the PWM waveform of the inverter output to make a sine wave, and the three-phase inverter circuit 7. Resistive voltage divider 15 as a voltage sensor for detecting output voltage feedback for control, AC filter when inverter is stopped Discharge reactor 16 for discharge of the capacitor 9, a resistor-divider 15 takes in the three-phase inverter circuit 7 an output voltage feedback detected by and a inverter circuit control unit 20 to PWM control.

Here, in the PWM converter 6, two sets of a switching element 11 and a diode 12 connected in parallel are connected in series, two in parallel, and a DC filter capacitor 13 connected in series is arranged in parallel. Configured. One end of the output terminal of the main transformer 3 is connected to the midpoint of one of the switching elements 11 connected in series via the contactor 4 and the first AC reactor 5, and the other output terminal of the main transformer 3. The end is connected to the midpoint of the other switching element 11 connected in series. Further, the midpoint of the DC filter capacitors 13 connected in series is grounded.
In addition, the three-phase inverter circuit 7 is configured by arranging two sets of switching elements 11 and diodes 12 connected in parallel in series, and arranging three DC filter capacitors 13 in parallel. Has been. And the three-phase alternating current is output from each midpoint of the switching element 11 connected in series.

The resistance voltage divider 15 is configured by connecting (Y-connection) three ends of resistors R1 and R2 connected in series. The connection point of one end of the three sets of resistors R1 and R2 connected in series is grounded, and the other end of each set is connected to each output line of the three-phase inverter circuit 7. Further, a connection point of a pair of resistors R1 and R2 is connected to one input terminal of an adder 22 described later.
Further, the discharge reactor 16 is configured by connecting (Y-connection) one end of three reactors L. The other end of each reactor L is connected to each output line of the three-phase inverter circuit 7.

  The inverter circuit control unit 20 also includes a voltage command generation circuit 21 that determines the effective value and waveform of the output voltage, and an adder that outputs the difference between the output from the voltage command generation circuit 21 and the output voltage feedback from the resistance voltage divider 15. 22, a voltage controller 23 that amplifies the output of the adder 22, a triangular wave carrier generation circuit 24, a comparator 25 that compares the output of the voltage controller 23 and the output of the triangular wave carrier generation circuit 24, and outputs a PWM modulation signal, and a comparator 25 is provided with a gate drive circuit 26 for driving and controlling the three-phase inverter circuit 7 by the PWM modulation signal from 25.

Next, the operation of the vehicular auxiliary power supply device configured as described above will be described.
First, the AC 25 kV voltage collected by the pantograph 1 from the AC overhead wire is supplied to the main transformer 3 via the circuit breaker 2. Then, the AC 25 kV voltage is stepped down to, for example, AC 400 V by the main transformer 3.
This single-phase AC 400 V voltage is converted into a DC link voltage, for example, DC 800 V, by an AC / DC converter including the contactor 4, the first AC reactor 5, and the PWM converter 6. Then, using this DC link voltage as an input, the three-phase inverter circuit 7 is operated to output a three-phase AC, for example, a 400V three-phase voltage, which is supplied to the load 10. At this time, the second AC reactor 8 and the AC filter capacitor 9 remove the harmonic components of the PWM waveform of the inverter output to make a sine wave.

Further, the output voltage feedback is measured by the resistance voltage divider 15 from the inverter output voltage and output to the adder 22. At this time, since the output voltage feedback is obtained by resistance-dividing the inverter output voltage by the resistance voltage divider 15, a DC component is also detected.
A sine wave voltage waveform that determines the effective value and waveform of the output voltage is output from the voltage command generation circuit 21 to the adder 22. The adder 22 takes the difference between the output of the voltage command generation circuit 21 and the output voltage feedback and outputs the difference to the voltage controller 23. Then, the output of the adder 22 is amplified by the voltage controller 23. The output of the voltage controller 23 is compared with the output of the triangular wave carrier generation circuit 24 by the comparator 25 and is output to the gate drive circuit 26 as a PWM modulation signal. The three-phase inverter circuit 7 is PWM-controlled by the gate drive circuit 26, and its output voltage is controlled.
Further, when the apparatus is stopped, the electric charge remaining in the AC filter capacitor 9 without being discharged is discharged by the discharge reactor 16.

  Here, in the conventional device, since the insulation transformer (leakage transformer) is used, the DC component of the output voltage generated in the three-phase inverter circuit 7 is cut off while passing through the insulation transformer, and the insulation transformer. Even when a slight direct current component is generated on the primary side of the magnetic field and becomes demagnetized (direct current excitation), it cannot be detected by the voltage sensor (PT), and the demagnetization cannot be suppressed.

  However, according to the present invention, since the midpoint of the DC filter capacitor 13 connected in series with the PWM converter 6 is grounded, the potential of the DC link portion can be fixed, and the conventionally required isolation transformer is unnecessary. It is possible to eliminate problems caused by using an insulating transformer. Since the resistance voltage divider 21 is used as a voltage sensor for detecting the output voltage feedback from the inverter output of the three-phase inverter circuit 7, the DC component of the output voltage generated in the three-phase inverter circuit 7 is also reliably detected. Thus, it is possible to suppress the demagnetization. As a result, in the case of a transformer that is weak against bias, it is possible to prevent a large primary current from flowing to stop protection.

  In addition, since the DC voltage component can be detected by the resistor voltage divider 15, the DC component of the output of the voltage instruction generating circuit 21 is set as a command that is sufficiently cut, and the DC controller can be suppressed by sufficiently increasing the gain of the voltage controller 23. it can. Furthermore, by increasing the gain of the voltage controller 23, the output voltage feedback can be made to follow the voltage command generation circuit 21, and the PWM control of the three-phase inverter circuit 7 can be performed stably.

  In addition, the resistance voltage divider 15 uses a large resistance value (several mega ohms or more) in order to ensure miniaturization and insulation between the main circuit and the control circuit. Therefore, when the load is completely unloaded, the charge of the AC filter capacitor 9 is not discharged and remains when the apparatus is stopped. However, since the discharge reactor 16 is installed, the charge of the AC filter capacitor 9 can be discharged when the apparatus is stopped. By selecting the reactor L to a large value, the impedance ωL during normal operation can be increased, so that even a small-sized device can withstand a short-time current during discharge, and the device can be downsized.

1 is a block diagram showing a network interface design / production system according to Embodiment 1 of the present invention; FIG.

Explanation of symbols

  3 main transformer, 6 PWM converter, 7 three-phase inverter circuit, 9 AC filter capacitor, 13 DC reactor, 15 resistance voltage divider (voltage sensor), 16 discharge reactor, 20 inverter circuit control unit.

Claims (2)

A main transformer that transforms and outputs an AC input; an output from the main transformer as an input; a PWM converter that generates and outputs a DC link voltage; and an output from the PWM converter as an input to generate a three-phase AC. A three-phase inverter circuit that outputs, a voltage sensor that detects an output voltage feedback for controlling the output voltage of the three-phase inverter circuit, and the output voltage feedback is taken in to control the output voltage of the three-phase inverter circuit An auxiliary power supply for a vehicle comprising an inverter circuit control unit,
In the PWM converter, the filter capacitor is connected in series between the output terminals, and the midpoint of the filter capacitor connected in series is grounded,
The vehicle auxiliary power supply device, wherein the voltage sensor is configured to detect the output voltage feedback by resistance-dividing the output voltage of the three-phase inverter circuit.   The AC filter capacitor for removing harmonic components of the PWM waveform of the output voltage of the three-phase inverter circuit, and a discharge reactor for discharging the charge of the AC filter capacitor are further provided. Auxiliary power supply device for vehicles as described.

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