JP2013099145A - Power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To charge a battery effectively from various external power supplies.SOLUTION: An inverter 12 has a plurality of legs formed by a series connection of switching elements 16 arranged between positive and negative buses. The inverter 12 receives DC power from a DC power supply on the positive and negative buses, inverts the DC power from the neutrals of the legs into AC power by switching of the switching elements and supplies the AC power to a motor 18. A diode bridge 22 has a plurality of legs each formed by a series connection of diodes 24, receives power from an external power supply 20 at the neutrals of the legs, and rectifies that power to obtain a DC output. One ends of the diode bridge 22 are connected commonly with one bus of the inverter, and the other ends are connected, respectively, with the neutrals of phases of the inverter 22.

Description

  The present invention relates to a power supply system including a diode bridge that rectifies power from an external power supply and an inverter that converts DC power into AC power and supplies the AC power to a motor.

  An electric vehicle is equipped with a driving motor, and travels by driving the motor with electric power from an on-vehicle battery. Therefore, it is necessary to charge a battery (secondary battery) with electric power from an external power source, and not only a dedicated charging facility but also a commercial 100V or 200V power source can be used as an external power source.

  It has been proposed that a hybrid vehicle equipped with a motor and an engine also has a mode of running as an electric vehicle and can be charged using an external power source.

JP-A-6-245322

  Here, there are various types of external power sources, and there is a demand for effectively charging a battery of an electric vehicle or a hybrid vehicle, regardless of which one is used.

  The present invention has a plurality of legs configured by serial connection of switching elements arranged between positive and negative buses, receives DC power from a DC power source on the positive and negative buses, and switches the DC from the midpoint of the legs by switching of the switching elements. It has multiple legs consisting of an inverter that converts power into AC power and supplies it to the motor, and diodes connected in series, accepts external power supplied from the outside at the midpoint of the leg, and rectifies this to direct current A diode bridge for obtaining an output, wherein one end of the diode bridge is commonly connected to one bus of the inverter, and the other end of the diode bridge is separately connected to the midpoint of each phase of the inverter. Features.

  In addition, it is preferable that a reactor is connected to each of midpoints of the plurality of legs of the diode bridge, and the electric power from the external power supply is input to the diode bridge via the reactor.

  Further, it is preferable to control the voltage of the DC output from the diode bridge by controlling the ratio of the ON period of the upper switching element to the lower switching element in each leg of the inverter.

  In addition, it is preferable to control the voltage of the DC output according to the required charging power for the external power source.

  Further, it is preferable that one end of the diode bridge is commonly connected to the negative bus of the inverter.

  According to the present invention, the output voltage after rectification of the diode bridge can be controlled by controlling the ratio of the ON period of the upper switching element and the lower switching element of the inverter, and the power from the external power supply can be controlled. Can do. Therefore, effective charging is possible using power from various external power sources.

It is a figure which shows the structure of the power supply system which concerns on embodiment. It is a figure which shows the waveform of the voltage command of a motor drive. It is a figure explaining the principle of embodiment. It is a figure which shows the structural example of an external power supply. It is a figure which shows the waveform of the battery current in single phase 100V. It is a figure which shows the enlarged waveform of the battery current in single phase 100V. It is a figure which shows the waveform of the motor current in single phase 100V. It is a figure which shows the waveform of the power supply current in single phase 100V. It is a figure which shows the enlarged waveform of the power supply current in single phase 100V. It is a figure which shows the waveform of the battery current in single phase 200V. It is a figure which shows the enlarged waveform of the battery current in single phase 200V. It is a figure which shows the waveform of the motor current in single phase 200V. It is a figure which shows the waveform of the power supply current in single phase 200V. It is a figure which shows the enlarged waveform of the power supply current in single phase 200V. It is a figure which shows the waveform of the battery current in AA 100V. It is a figure which shows the enlarged waveform of the battery current in AA 100V. It is a figure which shows the waveform of the motor current in AA 100V. It is a figure which shows the waveform of the power supply current in AA 100V. It is a figure which shows the enlarged waveform of the power supply current in AA 100V. It is a figure which shows the waveform of the battery current in DC400V. It is a figure which shows the expansion waveform of the battery current in DC400V. It is a figure which shows the waveform of the motor current in direct current | flow 400V. It is a figure which shows the waveform of the power supply current in DC400V. It is a figure which shows the enlarged waveform of the power supply current in DC400V. It is a figure which shows the structure of the electric power generation control system which concerns on other embodiment.

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

  FIG. 1 is a diagram illustrating a configuration of a power supply system mounted on an electric vehicle. The battery 10 is a secondary battery such as a lithium ion battery or a nickel metal hydride battery, and outputs a DC voltage of several hundred volts by connecting a large number of battery cells in series.

  The battery 10 is connected to the positive and negative buses of the inverter 12. A capacitor 14 is connected between the positive and negative buses of the inverter to smooth the voltage between the positive and negative buses of the inverter 12.

  The inverter 12 includes six switching elements 16 (16-1u, 16-2u, 16-1v, 16-2v, 16-1w, 16-2w), and the switching elements connected in series between the positive and negative buses. 16-1u and 16-2u constitute a u-phase leg, switching elements 16-1v and 16-2v constitute a v-phase leg, and switching elements 16-1w and 16-2w constitute a w-phase leg.

  All the switching elements 16 are composed of a switching element such as an IGBT and a diode that is connected in parallel to the reverse current, and the IGBT is an npn type, and the collector is disposed on the upper side (positive bus side). Yes.

  The midpoint of each phase leg is connected to each phase coil of the motor 18. Therefore, by appropriately controlling on / off of the switching element 16 of the inverter 12, a three-phase alternating current flows through the motor 18 and the motor 18 is driven.

  Here, during traveling, PWM (pulse width modulation) control of the inverter 12 is performed based on each phase voltage command to the motor 18 determined according to the target output torque determined from the accelerator depression amount of the vehicle. Thus, the drive of the motor 18 is controlled. The primary component of the motor applied voltage of each phase, the motor current, becomes a sine wave by PWM control, and the motor 18 is driven in a sine wave.

  Further, the vehicle is provided with a connector 28 having three RST terminals, and an external power source 20 is connected through the connector 28. The connector 28 is connected by connecting a pair of connection portions.

  Three terminals RST of the connector 28 are connected to the diode bridge 22 through the smoothing reactor 26. The diode bridge 22 includes six diodes 24 (24-1u, 24-2u, 24-1v, 24-2v, 24-1w, 24-2w) with the cathode facing upward (positive side). The diodes 24-1u and 24-2u constitute a u-phase leg, the diodes 24-1v and 24-2v constitute a v-phase leg, and the diodes 24-1w and 24-2w constitute a w-phase leg. Electric power from the external power source 20 is supplied via the connector 28 and the smoothing reactor 26. Therefore, power from the external power supply 20 is supplied to the diode bridge 22, and a rectified three-phase output is obtained on the positive side (upper side) of each leg of the diode bridge 22.

  The negative side of the diode bridge 22 is connected in common and connected to the negative bus of the inverter 12, and the positive side is independently connected to the coil ends of the respective phases of the motor 18. That is, the cathode of the upper diode of each leg of the diode bridge 22 is independently connected to the coil end of each phase of the motor 18.

  When the vehicle is stopped and the external power source 20 is connected via the connector 28 and the battery 10 is charged (during charging), the controller 30 includes the upper switching element 16-1 and the lower switching element 16 in the inverter 12. The average output voltage of the inverter 12 is controlled by changing the ON period ratio (duty ratio) of −2. That is, the inverter 12 obtains a voltage output corresponding to the voltage command by PWM control, but the ratio of the ON period of the upper switching element 16-1 and the lower switching element 16-2 at this time is not 1: 1. As a result, the average output voltage of the inverter 12 changes. This can be realized by applying an equal direct current component for all three phases to the PWM command voltage. Note that an ammeter 32 is provided in a path from the battery 10 to the inverter 12, and supplies a charge / discharge current of the battery 10 to the controller 30.

  Here, at the time of charging, the output torque of the motor 18 is 0, and the output of the inverter 12 is controlled so that the output torque of the motor 18 becomes 0. That is, the current of the motor 18 is 0, and the amplitude of the PWM control command voltage is also 0. In FIG. 2, the case where the command value of AC amplitude 0 and DC component V1 is given for the three phases is shown. Since the amplitude is 0, the command values of each phase overlap and cannot be distinguished.

  Usually, a triangular wave carrier comparison method is used for PWM control. At this time, the carrier is common to each phase, but in this configuration, a carrier having a phase shifted equally for each phase (120 ° for three phases) can be used. In this case, there is an effect that ripple of the power supply current is suppressed.

  In the present embodiment, the three-phase rectification output terminal of the diode bridge 22 is connected to each phase coil terminal of the motor 18. Therefore, the average voltage (hereinafter referred to as control voltage) of the three-phase rectified output terminals of the diode bridge 22 is also equal to the average output voltage of the inverter 12, and the output terminal of the diode bridge 22 is maintained at the control voltage as a whole. As a result, charging from the external power source 20 is controlled.

  FIG. 3 shows the principle of this embodiment. In the actual circuit, as shown in FIG. 1, the three outputs of the diode bridge 22 are separately connected to the three-phase coil ends of the motor. However, in the operation, the three outputs of the diode bridge 22 are averaged, and the single-phase boost chopper (switching elements 16-1 and 16-2) as shown in FIG. Will be the same.

  Thus, in this embodiment, the output voltage of the diode bridge 22 is controlled to a control voltage that is equivalent to the average output voltage of the inverter 12. Therefore, it is possible to control the power received from the external power supply 20 by controlling the inverter 12.

  For example, when the control voltage is lowered, more current flows toward the battery 10 and the amount of current received from the external power supply 20 increases. On the other hand, when the control voltage is increased, the current flowing toward the battery 10 is reduced, and the amount of current received from the external power source is reduced.

  FIG. 4 shows various external power sources 20. (A) is a DC 400V power supply provided for an electric vehicle, for example, at a charging station, etc., (B) is a single-phase AC 100V, 200V power supply provided, for example, from an outlet of a normal home, etc. , Single-phase three-wire AC 100V power source, (D) indicates a three-phase AC power source.

  Such various power supplies have a large difference in their capabilities. In the present embodiment, the charging current is controlled according to each external power source according to the type of external power source 20 to be connected. For example, the controller 30 has various power sources and an appropriate control voltage table inside, and controls the control voltage in accordance with a user input. In this case, it is preferable that the user can select a display using a display, a touch panel, or the like provided in the vehicle. It is also preferable to provide a dedicated display, touch panel or the like near the connector.

  Further, the controller 30 may automatically determine the connected external power source. That is, a voltmeter that measures the voltage at the three terminals of the connector 28 is provided, and the controller 30 determines which power source the connected external power source 20 is based on these voltage values. For example, the type of power supply can be determined from the zero-cross cycle, peak voltage, and the like.

  And when it determines, it is good to determine a control voltage and control switching of the inverter 12. FIG. In this case, the detected power source type may be displayed on the display to obtain user confirmation. In this case, if there is no input for a different power supply type within a predetermined time, the control voltage may be controlled to be appropriate for the detected power supply type.

  When starting charging, it is preferable that the control voltage is set sufficiently high, the charging current is set to 0, and then the control voltage is gradually lowered to control to a predetermined charging current.

  Here, in the present embodiment, the smoothing reactor 26 is disposed between the connector 28 and the diode bridge 22. Therefore, even if the internal impedance of the external power supply 20 is small, an excessive current is prevented from flowing from the external power supply to the battery 10.

  When the external power supply includes a transformer, the transformer functions as the smoothing reactor 26, and thus the smoothing reactor 26 can be omitted.

  In such a system, simulation results of changes in various currents when the charging current to the battery 10 is changed while maintaining the current of the motor 18 at 0 are shown in FIGS.

5 to 9 are single-phase 100 V, FIGS. 10 to 14 are single-phase 200 V, FIGS. 15 to 19 are single-phase three-wire AC 100 V (AA 100 V), and FIGS. 20 to 24 are DC 400 V. Is shown.
The current waveforms of the battery, motor, and power supply are shown, respectively. In any case, the charging command is 0 in the section from 0 to 0.10, 100 in the section from 0.1 to 0.45, and 200 (the magnitude of the current vector) in the section from 0.4 to 0.55. . It can be seen that the charging current can be controlled while the motor current is kept close to zero.

  FIG. 25 shows another embodiment in which a range extender 40, an external power supply option 50, an in-vehicle power supply option 60, and a non-contact charging option 70 are added.

  The range extender 40 is a vehicle-mounted power generation device, and drives a relay 42 connected to a three-phase connection line of the smoothing reactor 26 and the diode bridge 22, a generator 44 connected to the relay 42, and the generator 44. And an engine 46 to be used. When the range extender 40 is used, the relay 42 is turned on. Then, the rotor of the generator 44 is rotated by the driving force of the engine 46, and a three-phase alternating current is generated in the three-phase coil of the generator 44. By supplying the generated alternating current to the diode bridge 22 via the relay 42, an output rectified on the upper side of the diode bridge 22 is obtained. Accordingly, the range extender 40 has the same configuration as that when a three-phase AC power source is used as the DC power source 20.

  Then, the power generation amount of the generator 44 can be controlled by controlling the three-phase average voltage (control voltage) of the motor 18 by the inverter 12. The power generation amount control and the traveling control of the motor 18 can be performed simultaneously. In this case, the motor drive control can be performed independently of the charge control by superimposing the AC command component on the DC component V1 shown in FIG.

  In the generated output power control, the throttle is adjusted to control the engine output. When the throttle opening is constant, if the control voltage is lowered, the load increases and the output decreases because the rotational speed decreases. On the other hand, when the control voltage is increased, the load decreases and the rotation speed increases, so the output increases. Thus, by controlling the control voltage and the throttle, the engine torque and the generator torque are naturally balanced.

  The external power supply option 50 includes a switching relay 52 disposed between the three-phase output of the inverter 12 and the coil end of the motor 18, and a connector 54. Accordingly, when power supply is necessary, the motor 18 is disconnected by the switching relay 52 and the inverter 12 is connected to the connector 54. Then, AC power can be supplied to various loads via the connector 54. That is, output of direct current, single phase, three phase, 100 V, 200 V or the like can be obtained at the connector 54 by the control of the inverter 12. In this case, the feed power can be controlled independently of the charge control by superimposing the AC command component on the DC component V1 shown in FIG.

The in-vehicle power supply option 60 includes an inverter 62 composed of two legs connected in series between switching elements arranged between the positive and negative buses, and a connector 64 to which the output (the middle point of the two legs) of the inverter 62 is connected. Have. Therefore, the output of the battery 10 can be converted into single-phase AC power having an arbitrary voltage and output. For example, a single-phase 100V output can be obtained. Therefore, a single-phase 100V device mounted on the vehicle can be connected to the connector 64 and driven even during traveling.
The non-contact charging option 70 transmits power to a power receiving coil 72 from a power transmitting coil (not shown) installed on the ground. The power receiving coil 72 and a three-phase connection line of the power receiving coil 72 and the diode bridge 22 are used. A relay 74 for controlling the connection. Electric power is transferred between the power transmission coil and the power reception coil 72 through the space. The voltage appearing in the power receiving coil 72 is a single-phase alternating current, which is the same as that described with reference to FIG. According to this non-contact charging option 70, the battery 10 can be charged by receiving electric power while the vehicle is stopped or traveling if the place is provided with a power transmission coil.

  10 battery, 12 inverter, 14 capacitor, 16 switching element, 18 motor, 20 external power supply, 22 diode bridge, 24 diode, 26 smoothing reactor, 28 connector, 30 controller.

Claims (5)

It has a plurality of legs composed of series connection of switching elements arranged between the positive and negative buses, receives DC power from the DC power source on the positive and negative buses, and switches the DC power from the midpoint of the legs by switching of the switching elements An inverter that converts it into a motor and supplies it to the motor;
A diode bridge having a plurality of legs configured by series connection of diodes, receiving an external power supply supplied from the outside at the midpoint of the legs, and rectifying this to obtain a DC output
Including
One end of the diode bridge is commonly connected to one bus of the inverter,
A power supply system, wherein the other end of the diode bridge is separately connected to the midpoint of each phase of the inverter. The power supply system according to claim 1,
Having a reactor respectively connected to the midpoints of the plurality of legs of the diode bridge;
The external power supply is input to a diode bridge via a reactor. The power supply system according to claim 1 or 2,
A power supply system, wherein a voltage of a DC output from a diode bridge is controlled by controlling a ratio of an ON period of an upper switching element and a lower switching element in each leg of the inverter. The power supply system according to claim 1 or 2,
A power supply system that controls the voltage of the DC output in accordance with required charging power for the external power supply. The power supply system according to any one of claims 1 to 3,
One end of the diode bridge is commonly connected to the negative bus of the inverter.

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