JP6532780B2 - Auxiliary power supply - Google Patents

Description

  The present invention relates to an auxiliary power supply device for an electric vehicle.

  In general, auxiliary power supplies mounted on electric vehicles such as railway cars and streetcars are imported from high-voltage DC power directly taken from overhead wires, third rails, etc. (hereinafter referred to as overhead wires), or overhead wires, etc. The high voltage DC power obtained by converting the AC power through the rectifier is converted into three-phase AC power and low voltage DC power of a constant voltage required for the electric vehicle. Transformers operating at commercial frequencies used for isolation between input and output become heavyweight. Therefore, in recent years, in order to reduce the size and weight of equipment mounted on an electric vehicle, an auxiliary power supply device that does not include a transformer operating at a commercial frequency using a high frequency link method has been put to practical use (for example, non-patent Reference 1).

  FIG. 3 is a diagram showing an example of a conventional high frequency link type auxiliary power supply device. The auxiliary power supply 2 shown in FIG. 3 includes a first converter 50, a second converter 60, and a voltage source three-phase inverter 20.

  The first converter 50 converts the collected DC power into high frequency AC power by an inverter, isolates the AC power via a high frequency transformer for insulation function, and rectifies and smoothes the AC power. To generate DC power.

  The voltage source three-phase inverter 20 converts DC power generated by the first converter 50 into AC power by PWM modulation, and generates three-phase AC power having a constant effective voltage by a filter circuit.

  Similar to the first converter 50, the second converter 60 converts the collected DC power into high frequency AC power by an inverter, and isolates the AC power through a high frequency transformer for insulation function. Low voltage DC power is generated by rectifying and smoothing. Thus, the auxiliary power supply 2 generates three-phase AC power and DC power from the collected DC power, and supplies power to the load.

Kawamura Tsuneyoshi, 2 others, "High efficiency auxiliary circuit system for railway vehicles applying All-SiC element", Toshiba review, 2014, Vol. 69, No. 9

  Since the auxiliary power supply 2 of the high frequency link system shown in FIG. 3 does not include a heavy transformer operating at a commercial frequency, it can be made lightweight. However, the number of parts increased because of the installation of the two converters 50 and 60, and a remarkable effect was not necessarily obtained in terms of miniaturization. Therefore, it has been difficult to apply the high-frequency link type auxiliary power supply device to an electric vehicle with a limited mounting space.

  An object of the present invention made in view of such circumstances is to provide an auxiliary power supply capable of realizing miniaturization.

In order to solve the above problems, the auxiliary power supply device according to the present invention includes a converter for converting collected power into first DC power, and a first inverter for converting the first DC power into three-phase AC power. When a middle point obtained by dividing the voltage of the first DC power minute, a first transformer and voltage primary side input of between midpoint of each phase upper and lower arms of the first inverter, the first A rectifier for converting the secondary side output power of the first transformer into a second DC power, the converter converting the collected DC power into AC power by a second inverter, and a primary side input of the second transformer, by smoothing rectifies the secondary output of the second transformer, it characterized that you convert the first DC power.

Further, the auxiliary power unit according to the present invention, before Symbol converter, and controlling the duty ratio of the second inverter to the voltage of the second DC power constant.

  Furthermore, in the auxiliary power supply device according to the present invention, the first inverter performs PWM control so that the effective voltage of the AC power is constant.

  Furthermore, in the auxiliary power supply device according to the present invention, the converter controls the conduction ratio of the second inverter so that the voltage of the first DC power does not fall below a threshold.

In order to solve the above problems, an auxiliary power supply device according to the present invention, first to convert the converter for converting the electric power collector to the first DC power, the first DC power to three-phase AC power , A transformer having as a primary side a voltage between a middle point obtained by dividing the voltage of the first DC power and a middle point of upper and lower arms of each phase of the first inverter, and A rectifier for converting the secondary side output power of the converter into a second direct current power, the converter converts the collected direct current power into alternating current power by a second inverter, and rectifies and smoothes the alternating current power. Thus, it is characterized in that the first direct current power is converted, and the conduction ratio of the second inverter is controlled so that the voltage of the first direct current power does not fall below a threshold .

  According to the present invention, the auxiliary power supply can be miniaturized.

It is a block diagram showing an example of composition of an auxiliary power supply concerning one embodiment of the present invention. It is a figure which shows the voltage waveform between the U-phase of the voltage source three-phase inverter of the auxiliary power supply device which concerns on one Embodiment of this invention, V phase, W phase, and a UV phase. It is a block diagram which shows the structural example of the conventional auxiliary power supply device.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  The encoding auxiliary power supply according to the first embodiment of the present invention will be described below. FIG. 1 is a block diagram showing an example of the configuration of an auxiliary power supply according to an embodiment of the present invention. The auxiliary power supply 1 converts power collected from overhead wires and the like, and outputs sine wave three-phase AC power and low voltage DC power. In the example illustrated in FIG. 1, the auxiliary power supply device 1 includes a converter 10, a voltage source three-phase inverter (first inverter) 20, a three-phase transformer 30, and a rectifier 40.

  In addition, although the auxiliary power supply device 1 described in FIG. 1 uses the converter 10 of the high frequency link method, when the AC power is supplied via a transformer from an overhead wire or the like, the converter 10 collects the AC current. Other circuit schemes may be used to convert power into DC power and control its voltage.

  When DC power is supplied from an overhead wire or the like, converter 10 converts the collected DC power into AC power, isolates the AC power via a transformer, and rectifies and smooths the AC power. Generate DC power. Specifically, as shown in FIG. 1, the converter 10 includes a single-phase inverter (second inverter) 11, a small-sized transformer 12, a rectifier 13, an intermediate circuit 14, and a conduction ratio control unit 15 Equipped with

  The single-phase inverter 11 has a switching element (for example, an IGBT), and converts collected DC power into high frequency (for example, several KHz) AC power. Although a half bridge inverter is shown in the figure, it may be a full bridge inverter.

  The transformer 12 uses AC power input from the single-phase inverter 11 as a primary side input, and outputs a secondary side output insulated from the primary side to the rectifier 13. By generating high frequency AC power instead of the commercial frequency by the single-phase inverter 11, the transformer 12 can be made smaller and lighter.

  The rectifier 13 is formed of a semiconductor element such as a diode, and converts the secondary side output power of the transformer 12 into DC power (first DC power).

  The intermediate circuit 14 smoothes the DC voltage input from the rectifier 13 and keeps it constant. For example, the intermediate circuit 14 includes a reactor 141 and two capacitors 142 and 143. The DC voltage is divided by the capacitors 142 and 143.

  The conduction rate control unit 15 inputs the voltage value of the low voltage DC voltage output from the rectifier 40, and the current conduction rate of the single phase inverter 11 so as to make the low voltage DC voltage constant (maintain the desired value). Control (for example, PWM control).

  Therefore, although the DC power output from intermediate circuit 14 is also substantially constant, the transformer according to the voltage drop of the semiconductor element and the magnitude of the current of the three-phase AC power and low-voltage DC power output from auxiliary power supply device 1 The DC power fluctuates slightly because voltage drops of components such as wires and wires exist. Therefore, the voltage source three-phase inverter 20 controls on / off of the switching element by PWM control so that the effective voltage of the output three-phase AC power becomes constant even if the DC power slightly changes.

  Also, under rare load conditions, when the low-voltage DC power output from the auxiliary power supply 1 is unloaded and the three-phase AC power output from the auxiliary power supply 1 is loaded, the low-voltage DC voltage value Since the voltage does not fluctuate with a constant value, the conduction ratio of the single-phase inverter 11 controlled by the conduction ratio control unit 15 that performs feedback control of the voltage value becomes the minimum value. As a result, the DC voltage input to voltage-type three-phase inverter 20 may drop significantly, and voltage-type three-phase inverter 20 may fall below the minimum DC voltage that can be PWM-controlled with constant effective voltage of three-phase AC power. .

  Therefore, the conduction ratio control unit 15 receives a DC voltage output from the intermediate circuit 14 and controls the effective voltage of the three-phase AC power output from the voltage source three-phase inverter 20 at a constant DC voltage. The conduction rate of the single-phase inverter 11 is controlled (PWM control) so that the minimum voltage required for the above can be secured.

  The voltage source three-phase inverter 20 has a switching element (for example, an IGBT), and converts DC power input from the intermediate circuit 14 into three-phase AC power. This three-phase AC power is supplied to an external load (for example, an air conditioner).

  FIG. 2 is a diagram showing voltage waveforms among the U phase, the V phase, the W phase, and the U-V phase of the voltage source three-phase inverter 20 shown in FIG. Although three-phase AC power is output in this embodiment, it may be single-phase or two-phase.

  Three-phase transformer 30 has a middle point between two capacitors 142 and 143 (a middle point obtained by dividing the voltage of DC power converted by converter 10) and a middle point between upper and lower arms of each phase of voltage type three-phase inverter 20. The voltage between the two points is taken as the primary side input, and the secondary side output insulated from the primary side is output to the rectifier 40.

  The rectifier 40 is composed of a semiconductor element such as a diode, and converts the secondary side output power of the three-phase transformer 30 into low-voltage direct-current power (second DC power). The low-pressure linear power is supplied to an external load (for example, a controller).

  As described above, the auxiliary power supply device 1 converts the collected power into DC power by the converter 10, converts the DC power into AC power by the voltage source three-phase inverter 20, and supplies the AC power to an external load. . Further, a voltage between a midpoint obtained by dividing the voltage converted by the converter 10 by the three-phase transformer 30 and a midpoint between upper and lower arms of each phase of the three-phase inverter 20 is used as a primary side input. At 40, the secondary side output power of the three-phase transformer 30 is converted into low voltage DC power and supplied to an external load. With this configuration, the auxiliary power supply 1 can generate AC power and DC power supplied from one converter 10 to a load. Therefore, according to the present invention, the number of parts of the auxiliary power supply device can be reduced, and downsizing and cost reduction can be realized.

  Further, converter 10 can make the voltage of the low-voltage DC power converted by rectifier 40 constant by controlling the conduction ratio of single-phase inverter 11. Thereby, the DC power output from the intermediate circuit 14 is also constant.

  As described above, although the DC power output from the intermediate circuit 14 becomes constant due to the control of the conduction ratio of the single-phase inverter 11, there is a possibility that the DC power may slightly fluctuate. Therefore, even if the DC power output from the intermediate circuit 14 fluctuates, the effective voltage of the three-phase AC power to be output can be made constant by performing PWM control on the voltage source three-phase inverter 20.

  Moreover, it is preferable that the converter 10 controls the conduction ratio of the single-phase inverter 11 so that the voltage of the DC power to be output does not fall below the threshold. Thereby, when the voltage source three-phase inverter 20 performs PWM control of the effective voltage of the three phase AC power, the direct current voltage input to the voltage source three phase inverter 20 can control the effective voltage of the three phase AC power constant. It is possible to prevent the voltage from being lower than the lowest DC voltage.

  The converter 10 preferably uses AC power obtained by converting DC power collected from an overhead wire or the like as the primary side input of the transformer 12 and rectifies and smoothes the secondary side output of the transformer 12. As a result, instead of a heavy-duty transformer operating at a commercial frequency, a small-sized transformer 12 operating at high frequency can be used, and weight reduction can be achieved.

  Although the embodiments described above have been described as representative examples, it will be obvious to those skilled in the art that many modifications and substitutions can be made within the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications and changes are possible without departing from the scope of the claims. For example, the circuit diagram shown in FIG. 1 can be replaced with a circuit having the same function.

  As described above, according to the present invention, the auxiliary power supply can be miniaturized, which is useful for space saving when the auxiliary power supply is mounted on an electric vehicle.

Reference Signs List 1 auxiliary power supply 10 converter 11 single-phase inverter 12 transformer 13 rectifier 14 intermediate circuit 15 current ratio control unit 20 voltage type three-phase inverter 30 three-phase transformer 40 rectifier 141 reactor 142, 143 capacitor

Claims (5)

A converter for converting the collected power into a first DC power;
A first inverter for converting the first DC power into three-phase AC power;
A first transformer which uses as a primary side a voltage between a middle point obtained by dividing the voltage of the first DC power and a middle point of upper and lower arms of each phase of the first inverter;
A rectifier for converting the secondary side output power of the first transformer into a second DC power;
Equipped with
The converter converts the collected DC power into AC power by the second inverter, uses the AC power as the primary side input of the second transformer, rectifies and smoothes the secondary side output of the second transformer. by reduction, an auxiliary power unit, characterized that you convert the first DC power. Before Symbol converter, and controlling the duty ratio of the second inverter to the voltage of the second DC power constant, the auxiliary power supply device according to claim 1.   The auxiliary power supply device according to claim 2, wherein the first inverter performs PWM control so that an effective voltage of the AC power is constant.   4. The auxiliary power supply device according to claim 3, wherein the converter controls a conduction ratio of the second inverter such that a voltage of the first DC power does not fall below a threshold. 5. A converter for converting the collected power into a first DC power;
A first inverter for converting the first DC power into three-phase AC power;
A transformer which uses as a primary side a voltage between a middle point obtained by dividing the voltage of the first DC power and a middle point of upper and lower arms of each phase of the first inverter;
A rectifier for converting the secondary side output power of the transformer into a second DC power;
Equipped with
The converter converts the collected DC power into AC power with a second inverter, and then rectifies and smoothes the AC power to convert it into the first DC power, and the voltage of the first DC power is a threshold value. follows become not possible to control the conduction ratio of said second inverter as auxiliary power supply it said.

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