JP4934561B2 - Power converter - Google Patents

Description

  The present invention relates to a power conversion device using a storage battery, and particularly to a power conversion device including an auxiliary converter.

  Recently, a vehicle driven by an electric motor has been attracting attention in order to deal with environmental problems such as noise, exhaust, and resource saving with respect to a vehicle driven by an internal combustion engine such as a gasoline engine or a diesel engine. Some of these systems require a power source for an electric motor, and some have a storage battery for driving the generator by the engine to generate electric power and absorbing load fluctuations of the electric motor (see, for example, Patent Document 1). ).

In order to further increase the efficiency of these motor drive systems, it is effective to increase the operating voltage of the generator, the motor, and the intervening power converter. In general, there are low-pressure loads such as air conditioners and lights in the vehicle other than the motor for driving the vehicle, and it is reasonable to share the power source of the low-voltage load and the motor for driving the vehicle from the viewpoint of simplification of the system. It is. In this case, some have a dedicated power converter for supplying power to the low-voltage load (see, for example, Patent Document 2).
JP-A-10-191503 JP-A-9-74601

  In the system described in Patent Document 1, a generator is driven by an engine to generate AC power, and after the AC power is converted to DC power by a forward converter, a storage battery for storing DC power, and a vehicle drive Inverters that supply AC power to the motor are connected in parallel. The storage battery serves as a buffer that absorbs transient power fluctuations, and when the engine or generator serving as a power source fails, the storage battery alone cannot run for a long time.

  In preparation for such a failure of the power generation device, it is desirable to provide an emergency charging function so that the storage battery can be charged from the outside of the vehicle. However, in order to receive power supply from the outside, the following problems arise.

(A) Considering that the failure of the generator on the power receiving side is a factor in the first place, both the power supply side and the power receiving side are insulated by the transformer from the viewpoint of protection against ground faults and noise in the power system, and AC power is A transmission configuration is desirable.
(B) When both the power supply side and the power reception side are connected by an emergency power supply cable and the wiring length and wiring inductance cannot be ignored with respect to the switching speed of the power converter, it is necessary to pay attention to the jump due to the reflection of voltage and current. There is.
(C) Since the emergency power receiving function is used only in the event of an emergency or emergency such as a generator failure, existing equipment and functions should be diverted as much as possible and shared, and new equipment to be added is the minimum necessary. I want to limit it to the limit.

  The present invention uses a storage battery as a power source and supplies power to a low-voltage load such as an illumination or an air conditioner in the vehicle, in addition to the first power converter (main converter) that supplies power to a motor for driving the vehicle. A second power converter (auxiliary converter) that is connected to a low-voltage load through a filter circuit for waveform shaping and a transformer for insulation, and supplies an AC voltage supplied to the low-voltage load. In the power converter for detecting and controlling the AC voltage, a terminal for connecting an emergency AC voltage source or AC voltage source to the low-voltage load side of the transformer, and means for controlling the DC voltage of the auxiliary converter The main feature is that the auxiliary converter is also used as a power converter for charging.

  According to the present invention, the power supply side and the power receiving side can be insulated by connecting the emergency AC voltage source and the auxiliary converter used for charging via the transformer.

  Further, since the high-frequency component generated by the switching of the auxiliary converter can be removed by the waveform shaping filter circuit, it is possible to suppress the jump of voltage and current generated in the emergency power supply cable connecting the power supply side and the power reception side. .

  In addition, the power converter (auxiliary converter) used for charging, the filter circuit for waveform shaping, and the transformer for insulation can be shared with facilities for supplying power to the low-voltage load. Additional costs involved can be reduced.

  In addition, the present invention can also be used as an emergency power supply device, and even when an AC power supply device for power supply cannot be prepared separately, the two systems of the present invention are connected via an emergency power supply / reception terminal. It is only possible to exchange power with each other.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

A power conversion apparatus according to a first embodiment of the present invention is shown in FIG.
In FIG. 1, a power conversion device 1 includes a storage battery 2, a first power converter (main converter) 4 that converts DC power supplied from the storage battery 2 into AC power, and a DC of the storage battery 2 and the main converter 4. Smoothing capacitor 3 connected in parallel to the side, AC motor 5 driven by the AC power supplied from main converter 4, and second power conversion connected in parallel to the DC side of storage battery 2 and main converter 4. , A smoothing capacitor 6 connected in parallel to the DC side of the storage battery 2 and the auxiliary converter 7, a DC voltage detector 25 for detecting the voltage of the smoothing capacitor 6, and the auxiliary converter 7. An AC current detector 24 for detecting the AC current of the current, a three-phase AC transformer 10 of Δ-Y connection, a filter reactor 8 for connecting the AC side of the auxiliary converter 7 and the Δ side of the three-phase AC transformer 10, The filter reactor on the Δ side of the three-phase AC transformer 10 Filter capacitor 9 connected in parallel, AC voltage detector 11 for measuring the line voltage on the Y side of the three-phase AC transformer 10, neutral point on the Y side of the three-phase AC transformer 10, and ground point g1 It is comprised from the switch 23 which connects.

  A low-voltage AC load 12, the Y side of the three-phase AC transformer 10 in the power conversion device 1, and the low-voltage AC load 12 are connected to the power conversion device 1 via the switch 22 and are grounded to the ground point g2. The phase AC power source 21 is connected to the Y side of the three-phase AC transformer 10 in the power converter 1 via the switch 20.

  FIG. 2 shows a control device of the power conversion device 1. In FIG. 2, the control device of the power conversion device 1 includes means 30 for obtaining an effective value by converting rotational coordinates of outputs (AC load voltage detection values) Vuv and Vvw of the AC voltage detector 11 at AC frequencies, and an AC load voltage. A voltage for voltage control using the subtractor 31 for obtaining the difference between the commands Vd *, Vq * and the output of the coordinate transformation 30 (AC load voltage effective value) Vd, Vq, and the output of the subtractor 31 (AC load voltage deviation) A controller 32; a switch 40 that can open and close the output of the voltage controller 32; A subtractor 41 for obtaining a difference between the DC voltage command Ecf * and the output (DC voltage detection value) Ecf of the DC voltage detecting means 25, and a voltage controller 42 for performing voltage control using the output (DC voltage deviation) of the subtractor 41. And exchange Means 43 for obtaining the effective values Id and Iq by rotationally converting the outputs (alternating currents) iu and iv of the current detector 24 at the alternating frequency, and the outputs (alternating current commands) Id * and Iq * of the voltage controller 42 A subtractor 44 that obtains the difference between the output (AC current effective value) Id and Iq of the rotating coordinate conversion means 43, a current controller 45 that performs current control using the output (AC current deviation) of the subtractor 44, and current control A switch 46 capable of opening and closing the output of the adder 45; an adder 47 for calculating the sum of the output of the adder 33 and the output of the switch 46; 34, the divider 35 for normalizing the output of the stationary coordinate conversion means 34 with the output (DC voltage detection value) Ecf of the DC voltage detection means 25, and the PWM pulse signals Su, Sv, Sw from the output of the divider 35. pulse Composed of the modulator 36.

  The auxiliary converter 7 performs switching according to outputs (PWM pulse signals) Su, Sv, Sw of the pulse width modulator 36. The open / close state of each switch in the normal mode in which the auxiliary converter 7 is operated as an AC voltage source and power is supplied to the low-voltage AC load 12 is shown below.

Switch 20 OFF, Switch 22 ON, Switch 23 ON, Switch 40 ON, Switch 45 OFF
A voltage drop occurs with respect to the AC output voltage of the auxiliary converter 7 according to the resistance of the filter reactor 8 and the magnitude of the current flowing through the filter reactor 8. In order to keep the voltage supplied to the low-voltage AC load 12 constant, it is necessary to configure the feedback control so that the AC load voltage supplied to the low-voltage AC load 12 is detected and matches the rated voltage of the low-voltage AC load 12. . For this purpose, an AC voltage detector 11 and a voltage controller 32 are provided. From the viewpoint of circuit protection, the auxiliary converter 7 and the low-voltage AC load 12 are insulated by the three-phase AC transformer 10. Further, in order to determine the phase voltage supplied to the low-voltage AC load 12 (so that the neutral point does not float), the low-voltage AC load side of the three-phase AC transformer 10 is Y-connected, and the neutral point is the case of the power converter 1. Install at (ground potential g1).

  On the other hand, the open / close state of each switch in the emergency mode in which the auxiliary converter 7 is operated as a forward converter and the storage battery 2 is charged by receiving power supply from the outside is shown below.

Switch 20 ON, Switch 22 OFF, Switch 23 OFF, Switch 40 OFF, Switch 45 ON
When charging the storage battery 2, the terminal voltage of the smoothing capacitor 6 needs to be higher than the terminal voltage of the storage battery 2. For this reason, the DC voltage detector 25 and the voltage controller 42 are provided, and feedback control for the terminal voltage of the smoothing capacitor 6 is configured. Since the current flowing through the filter reactor 8 and the three-phase AC transformer 10 flows in accordance with the potential difference between the AC output voltage of the auxiliary converter 7 and the AC output voltage of the three-phase AC power supply 21, the current of the three-phase AC voltage 21 is reversed. If the AC output voltage and the current to be supplied are given, the AC output voltage of the auxiliary converter 7 can be obtained. Therefore, the AC voltage detector 11, the AC current detector 24, and the current controller 45 are provided, and current feedback control is performed using the output of the voltage controller 42 as an AC current command. Since the ground potential g2 of the three-phase AC power supply 21 and the ground potential g1 of the power converter 1 are not necessarily the same potential, it is necessary to open the switch 23.

  A second embodiment of the present invention is shown in FIG. FIG. 3 shows a configuration example when a plurality of power conversion devices 1 shown in the first embodiment are connected. The plurality of power conversion devices 1 includes a first power conversion device 1, a second power conversion device 1 ', and a third power conversion device 1 ".

  3 includes a first power conversion device 1, a second power conversion device 1 ′, a third power conversion device 1 ″, a power bus line 50 for emergency power supply and reception, and a low-voltage AC load. A common power bus line 51, a switch 22 connecting the Y side of the three-phase AC transformer in the first power converter 1 and the power bus line 50, and a three-phase AC transformer in the first power converter 1 A switch 20 that connects the Y side of the transformer and the power bus line 51, a switch 22 'that connects the Y side of the three-phase AC transformer in the first power converter 1' and the power bus line 50, a first Switch 20 ′ for connecting the power bus line 51 and the Y side of the three-phase AC transformer in the power converter 1 ′, and the Y side of the three-phase AC transformer and the power bus line in the first power converter 1 ″ Switch 22 ″ connecting 50 and the three-phase AC converter in the first power converter 1 ″. Switch 20 ″ for connecting the power bus line 51 to the Y side of the device, a first low-voltage AC load 12 connected to the power bus line 51, and a second low-voltage AC load 12 ′ connected to the power bus line 51. And a third low-voltage AC load 12 ″ connected to the power bus line 51.

  The open / close state of each switch in the normal mode in which the power converters 1, 1 ', 1 "are operated as an AC voltage source and power is supplied to the low-voltage AC loads 12, 12', 12" is shown below.

  Switch 20 OFF, Switch 22 ON, Switch 20 'OFF, Switch 22' ON, Switch 20 "OFF, Switch 22" ON

  By connecting the low-voltage AC loads 12, 12 ′, 12 ″ to the common power bus line 51, even if one of the three power converters fails, power can be supplied to all loads, and fail-safe characteristics When the power converter 1 fails, the switch 22 is turned off, and when the power converter 1 ′ or 1 ″ fails, the switch 22 ′ or 22 ″ is turned off, respectively. .

  The power converter 1 is used as an AC voltage source to charge the storage battery of the power converter 1 ′, and the open / close state of each switch in the emergency mode in which the power converter 1 ″ supplies power to the low-voltage AC loads 12, 12 ′, 12 ″. It is shown below.

  Switch 20 ON, Switch 22 OFF, Switch 20 'ON, Switch 22' OFF, Switch 20 "OFF, Switch 22" ON

  In this embodiment, a plurality of power conversion devices of the present invention are connected, and two systems are provided: a power bus line 51 for supplying power to the low-voltage AC load and a power bus line 50 for emergency power supply and reception. Thus, the storage battery can be charged without stopping the power supply to the low-voltage AC load.

FIG. 1 is a configuration diagram illustrating a power conversion apparatus according to a first embodiment of the present invention. FIG. 2 is a diagram illustrating a control device of the power conversion device in FIG. 1. FIG. 3 is a configuration diagram when a plurality of power converters according to the second embodiment of the present invention are connected.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power converter 2 Storage battery 3 1st smoothing capacitor 4 1st power converter (main converter)
5 AC motor 6 Second smoothing capacitor 7 Second power converter (auxiliary converter)
8 Filter reactor 9 Filter capacitor 10 Three-phase AC transformer (Δ-Y connection)
DESCRIPTION OF SYMBOLS 11 AC voltage detector 12 Low voltage AC load 20 Three-phase switch 21 Three-phase AC power supply 22 Three-phase switch 23 Switch 24 AC current detector 25 DC voltage detector 30 Rotation coordinate conversion means 31 Subtractor 32 Voltage controller (ACR: Automatic Abbreviation of Voltage Regulator)
33 Adder 34 Static coordinate conversion means 35 Divider 36 Pulse width modulator (PWM: Abbreviation of Pulse Width Moduration)
40 switch 41 subtractor 42 voltage controller (AVR)
43 Rotating coordinate conversion means 44 Subtractor 45 Current controller (ACR: Automatic Current Regulator)
46 switch 47 adder Ecf * terminal voltage command value of second smoothing capacitor Ecf terminal voltage detection value of second smoothing capacitor iu, iv u, v-phase output current detection value Vuv of second power converter 7 , Vvw V-w voltage detection value between Y side u-v of three-phase AC transformer 10 g1 Ground potential due to case installation of power converter 1 g2 Ground potential of three-phase AC power supply 21 su, sv, sw Second U, v, w phase switching signal of power converter 7 Vd *, Vq * Y side d, q axis voltage command value Vd, Vq of three phase AC transformer 10 Y side d, q axis of three phase AC transformer 10 Voltage effective value Id *, Iq * d of the second power converter 7, q-axis output current command value Id, Iq second power converter) d, q-axis output current effective value

Claims (4)

A storage battery,
A first power converter that converts DC power supplied by the storage battery into AC power;
An AC motor driven by the AC power supply before Symbol first power converter,
Connected in parallel with the storage battery and the DC portion of the first power converter, a second power converter for converting DC power supplied by the battery to AC power,
A filter circuit for shaping the AC output of the second power converter;
A transformer connected to the filter circuit;
AC load connected to the transformer;
A first switch disposed between the transformer and the AC load;
A second switch disposed on the AC load side of the transformer and capable of connecting the AC load and an AC voltage source in parallel;
A third switch for connecting a neutral point of the transformer on the side of the AC voltage source and ground;
The AC load side of the transformer is operated by operating the second power converter when the first switch is connected, the second switch is opened, and the third switch is connected. First control means for performing voltage control of
When the first switch is opened, the second switch is connected, and the third switch is opened , voltage control of the DC unit is performed by operating the second power converter. And a second control means. 2. The power conversion device according to claim 1, further comprising a DC voltage detecting means for measuring a voltage of the smoothing capacitor , wherein the second control means performs voltage control using an output of the DC voltage detecting means. A power converter. The power converter of claim 2, further comprising a ac current detecting means for measuring the AC side output current of the second power converter, said second control means outputs said ac current detecting means A power conversion device that performs voltage control using a power converter. A storage battery,
A first power converter that converts DC power supplied by the storage battery into AC power;
A smoothing capacitor connected in parallel with the storage battery on the DC side of the first power converter;
An AC motor driven by AC power supplied by the first power converter;
A second power converter that is connected in parallel to the DC side of the storage battery and the first power converter, and converts the DC power supplied by the storage battery into AC power;
A filter circuit for shaping the AC output of the second power converter;
A transformer connected to the filter circuit;
A low voltage AC load connected to the transformer;
AC voltage detection means for measuring the AC load side voltage of the transformer;
Using the output of the AC voltage detection means, the first control means for performing voltage control on the low-voltage AC load side of the transformer by operating the second power converter,
AC voltage source connected in parallel with the low-voltage AC load on the low-voltage AC load side of the transformer,
A plurality of power converters installed with second control means for controlling the voltage of the smoothing capacitor by operating the second power converter,
Each of the power converters of the plurality of power converters is connected to the AC voltage source by a first power bus line for an emergency receiving power supply via a first switch means, and the power converters of the plurality of power converters Each power conversion device is connected to each low-voltage AC load via a second switch means through a common second power bus line, and charges the storage battery without stopping power supply to the low-voltage AC load. The power converter characterized by the above-mentioned.

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