JP2006025518A - Power converter and dual power supply vehicle mounting it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power converter capable of reducing both inverter loss and motor loss, and to provide a dual power vehicle mounting it. <P>SOLUTION: In the power converter for generating a pulse voltage of AC voltage waveform from the output voltage of a DC voltage source, the DC voltage source has a voltage source output part (terminal) outputting three or more potentials including a common potential, the power converter has a switching means connecting with one (terminal) of three or more potentials and applying a voltage to the output part of the power converter, and each switching means generates pulse voltage by controlling the on/off pulse width. Since a switching means for connecting three or more potentials selectively is provided, loss in both the motor and the power converter can be reduced both when a high voltage is applied to the motor and when a low voltage is applied to the motor. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a power conversion device and a dual power supply vehicle equipped with the same.

As a conventional technique, a configuration for driving a motor with high efficiency and high response using a fuel cell as a main power source is disclosed in Japanese Patent Application Laid-Open No. 2002-118981 (see Patent Document 1). In this example, as shown in FIG. 1, the electric storage device has a vehicle configuration including two power sources connected in parallel with the fuel cell via the DC-DC converter, and the output voltage of the DC-DC converter is controlled. The aim is to improve output efficiency as a power source.
Further, even in an electric vehicle having two power sources, ie, a motor driving capacitor and an auxiliary driving capacitor, electric power can be transferred between both capacitors by connecting the two capacitors via a DC-DC converter.
JP 2002-118981 (paragraphs 0004-0006, FIG. 1)

However, since this conventional example has a configuration in which two power storage devices are connected in parallel using a DC-DC converter, the use of the DC-DC converter increases the size of the system and reduces the cost. For example, when the motor is driven using both electric powers of both storage batteries, or when the electromotive force of the motor is stored, a problem such as a large loss occurs.
Therefore, the present invention relates to a conversion device that performs voltage conversion using a plurality of power supplies, but can freely control switching and distribution of input / output power of the plurality of power supplies, and can supply power from a voltage source. It is a first object to enable control. Moreover, this invention makes it the 2nd objective to provide the power converter device (unit) which can reduce both an inverter loss and a motor loss more. Furthermore, a third object of the present invention is to provide a dual power supply vehicle equipped with such a power conversion device.

In order to solve the above-described problems, the power conversion device according to the first invention provides:
A power conversion device that generates an AC voltage waveform from a DC voltage source output voltage as a pulse voltage,
The DC voltage source includes a voltage source output unit (terminal) that outputs three or more potentials including a common potential,
The power conversion device includes switching means for connecting to one (terminal) of the three or more potentials and applying a voltage to the output unit of the power conversion device,
Each of the switching means generates the pulsed voltage by controlling the on / off pulse width (that is, each switching means selects and connects one potential, and switches the connection to change the pulsed voltage. ),
It is characterized by that.

The power converter according to the second invention is
When the voltage source output unit arranges the potentials between the output units in order of magnitude, the potential difference from the potential of the adjacent output unit is set to a different magnitude.

Furthermore, the power conversion device according to the third invention provides
The AC voltage waveform is a multiphase AC voltage waveform, and is a waveform for driving a multiphase AC motor.

Furthermore, the power conversion device according to the fourth invention provides:
Furthermore, the switching means controls the input / output electric energy of each DC voltage source of the voltage source output unit.

Furthermore, the power conversion device according to the fifth invention provides
At least one of the DC voltage sources is a capacitor.

Furthermore, the power conversion device according to the sixth invention provides:
A plurality of sets including the motor and the power converter are provided,
The DC voltage source that supplies power to these power converters is shared by the plurality of power converters,
It is characterized by that.

Furthermore, the dual power supply system vehicle according to the seventh invention is:
A two-power-source vehicle equipped with any of the power conversion devices described above,
The DC voltage source includes two DC voltage source means having different voltages,
The higher voltage of the DC voltage source means is a high load battery for driving a motor.
It is characterized by that. That is, the present invention assumes that the above-described power conversion device is mounted and used in a dual power supply system vehicle that uses a high-load battery for driving a motor.

  According to the first invention, the voltage applied to the motor is provided by providing switching means for selectively connecting three or more input potentials (that is, any potential is intermittently connected by turning on and off). In both cases where a high voltage is required and a low voltage is sufficient, the loss of both the motor and the power converter can be reduced. In addition, since only one power element (that is, a bidirectional element) passes between the power source and the motor, and the other switches can be configured as diodes, the loss and cost can be further reduced. Can be achieved.

Further, according to the second invention, by setting the potential difference between the output portions of the voltage source to different values, the type of the magnitude of the pulse voltage applied to the motor is conventional (the potential difference is the same). since Yo potential can be increased compared to the set being), it is possible to further reduce the loss.

  Moreover, according to 3rd invention, it is applicable to the three-phase alternating current motor most widely used as an alternating current motor.

  Further, according to the fourth invention, since the input / output power of each DC voltage source can be controlled, it is possible to control each voltage source by actively changing which of a plurality of potentials is used to drive the motor. The power to be supplied can be changed. Further, when a voltage source having a limited capacity such as a battery is used, the SOC of each battery can be controlled to an optimum value by controlling the power supplied from each battery.

  Further, according to the fifth invention, the power converter can set the power supplied from the power source to an arbitrary value, so that even a capacitor having a small energy density can be used as a stable voltage source. it can. In addition, the system can be miniaturized by using a capacitor.

  A sixth invention includes a plurality of motors and a plurality of power converters, and a DC voltage source is a system shared by the plurality of power converters. In a system including a plurality of motors such as a series hybrid vehicle, By operating a plurality of power converters in a coordinated manner, it is possible to drive efficiently while controlling the SOC (charge state) of a plurality of batteries. The input / output power of the voltage source can be precisely controlled.

  In addition, the seventh invention can be easily applied to a dual power supply system vehicle, and the DC-DC converter used in the conventional dual power supply system vehicle is not necessary, so that the system configuration is simplified. Loss can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First Embodiment First, as a first embodiment of the present invention, a power converter by three-phase three-level, all bidirectional switching will be described in detail. FIG. 2 is a diagram showing a circuit configuration of the current converter according to the first embodiment of the present invention. As shown in the figure, the first battery 10 and the second battery 20 constitute a DC voltage source. The DC voltage source generates three potentials by using the low voltage side of the two batteries as a common potential. The voltage Vbh of the battery 10 is higher than the voltage Vbm of the battery 20. Vbh−Vbm is set to a value larger than Vbm.
That is, Vbh> Vbm (1)
Vbh−Vbm> Vbm (2)
It is.
Reference numeral 30 denotes a power converter that drives the AC motor 40 by converting those voltages to generate an AC voltage. The power converter 30 includes a capacitor C1 that stabilizes the supply voltage Vbh of the battery 10, a capacitor C2 that stabilizes the supply voltage Vbm of the battery 20, the U phase, the V phase, and the W phase of the motor 40, and the battery It is composed of switch groups 31, 32, and 33 that selectively connect only one of the common potential voltage (hereinafter referred to as 0V), the high potential side voltage of the battery 10, and the high potential side voltage of the battery 20. .

  Each switch group has the following configuration. Since the U-phase, V-phase, and W-phase switch groups all have the same configuration, only 31 U-phase switch groups will be described. Tr11 and Tr12 are IGBTs (power elements) constituting a bidirectional switch for intermittently connecting between the U phase of the motor and the voltage Vbh. Tr21 and Tr22 are bidirectional switches that intermittently connect the U phase and the voltage Vbm. Tr31 and Tr32 are bidirectional switches that intermittently connect between the U phase and the common potential voltage. The above switches constitute a U-phase switch group. Tr11 and Tr12, Tr21 and Tr22, and Tr31 and Tr32 each operate as a bidirectional switch, but only one of these three sets is turned on at a certain time interval. Therefore, a voltage of Vbh, Vbm, or 0V is applied to the U phase of the motor. The V-phase switch group 32 and the W-phase switch group 33 have the same configuration as the U-phase switch group 31.

Next, the operation will be described. The voltage to be applied to the motor is generated by adjusting the proportion of time during which Vbh, Vbm, and 0 V are applied per unit time.
FIG. 18 is a timing chart showing the U-phase output voltage waveform in the first embodiment, and FIG. 19 is a diagram showing the state of the gate signal of the IGBT constituting the U-phase switch group in the first embodiment. It is. Hereinafter, description will be made with reference to these drawings. That is, FIG. 18 shows signals applied to the gate of the U-phase switching element in the following three cases (a) to (c). FIG. 19 shows the U-phase output voltage.

(A) When the motor applied voltage can be generated with the battery voltage Vbm without performing field weakening, the switch (U phase: Tr11 and Tr12) connected to Vbh is held off and connected to Vbm and 0V. PWM (pulse width modulation control) is performed by alternately turning on and off the switches (U phase: Tr21 and Tr22, Tr31 and Tr32). In this case, Vbm, which is a low voltage, is switched (FIG. 18A), so that the loss generated in the power element is small, and the loss of the switch group 31 as a power converter is naturally small. Further, since the pulse voltage applied to the motor at this time is generated from the low voltage Vbm, the harmonic component is reduced and the iron loss of the motor 40 can be reduced.

(B) When Vbm requires field weakening but Vbh-Vbm does not require field weakening, keep the switch connected to 0V (U phase: Tr31 and Tr32) off and Vbh PWM is performed by alternately turning on and off the switches (U phase: Tr11 and Tr12, Tr21 and Tr22) connected to Vbm. In this case, the voltage Vbh-Vbm smaller than Vbh is switched (FIG. 18B), so that the loss generated in the power element can be minimized, and the loss of the switch group 31 as a power converter is naturally small. I'll do it. Further, since the pulse voltage applied to the motor at this time is generated from Vbh-Vbm, the harmonic component is reduced and the iron loss of the motor 40 can be reduced.

(C) When it is necessary to perform field weakening at Vbh-Vbm, the switch connected to Vbm (U phase: Tr21 and Tr22) is kept off, and the switch connected to Vbh and 0 V (U phase: Tr11) And Tr12, Tr31 and Tr32) are turned on and off (FIG. 18 (c)). In this case, since the field weakening current can be reduced, the loss of the switch group 31 and the motor 40 as the power converter can be reduced.
With the above operation, three types of pulse voltages Vbm, Vbh-Vbm, and Vh can be applied to the motor according to the required voltage, and such a configuration is suitable. It is. On the other hand, when the potentials are set at equal intervals, that is, when Vbh−Vbm = Vbm, only two kinds of pulse voltage can be generated, so that the loss becomes larger than in this embodiment.
As described above, in this embodiment, the loss of the power converter and the motor can be reduced even if the number of DC voltage potentials is the same as in the conventional example.

Second Embodiment Next, as a second embodiment of the present invention, a power converter using three-phase three-level, partly bidirectional switching will be described in detail. FIG. 3 is a diagram showing a circuit configuration of the current converter according to the second embodiment of the present invention. As shown in the figure, FIG. 3 (this embodiment) and FIG. 2 (first embodiment) are connected to 0 V and the switches connected to the voltage Vbh in the switch groups 31a, 32a and 33a of each phase. The configuration of the switch is different, but the other components are the same. Although the U-phase switch group will be described, the same applies to the other phases. The switch connected to the higher voltage Vbh is composed of IGBT Tr11 and diode D1. The switch connected to 0V is composed of an IGBT Tr31 and a diode D3. In this configuration, since the battery voltage Vbh is higher than the battery voltage Vbm, diodes D1 and D3 are used in place of Tr12 and Tr32 in the first embodiment, respectively, as reverse current switches of these two switches. . Regardless of whether the U-phase current iu is positive or negative, if any one of Tr11, Tr21 and Tr22, or Tr31 is turned on, the voltage potential at which the turned-on switch is connected is connected. It can be applied to the U phase of the motor. In this configuration, only one bidirectional switch (power element) is required for each phase, and only one bidirectional switch is interposed between the power source and the motor, thereby further reducing current loss. Furthermore, cost reduction can be achieved.

FIG. 15 is a diagram for explaining the flow of current when the switch having the highest potential is on in the second embodiment, that is, the operation when “Tr11” is turned on. When Tr11 is on, Tr21, Tr22 and Tr31 are off. When the U-phase current iu is positive, current flows through Tr11. When the U-phase current iu is negative, current flows through D1, so that the voltage Vbh is applied to the U-phase of the motor.
FIG. 16 is a diagram for explaining the flow of current when the second highest potential switch is on in the second embodiment, that is, the operation when “Tr21 and Tr22” are turned on. is there. When Tr21 and Tr22 are on, Tr11 and Tr31 are off. When the U-phase current iu is positive, current flows through Tr21, and when it is negative, it flows through Tr22. Therefore, a voltage of Vbm is applied to the U-phase of the motor.

FIG. 17 is a diagram illustrating the flow of current when the switch having the lowest potential is on in the second embodiment, and illustrates the operation when “Tr31” is turned on. When Tr31 is on, Tr11, Tr21 and Tr22 are off. When the U-phase current iu is positive, the current flows through D1, and when it is negative, the current flows through Tr31. Therefore, a voltage of 0 V is applied to the U-phase of the motor.
In order to prevent a short circuit from occurring during switching in a power converter such as an inverter, it is common to provide a dead time that is a time during which the semiconductor switches are simultaneously turned off. When the dead time is provided, an excessive voltage is applied to the switch unless a path through which current flows during the dead time period is secured. In the present embodiment, as shown in FIG. 4, since a path for current flow is secured by the diode D1 when the current is positive and by D3 when the current is negative during the dead time period, Can be prevented from being added to the power element.

Next, a description will be given in terms of power supplied from two batteries. In the present embodiment, the ratio of the power supplied from each battery can be controlled to a desired value according to the state of the two batteries 1 and 2.
FIG. 13 is a diagram showing the configuration of the U-phase portion of the power converter of this embodiment and the drive signal generation unit thereof, and FIG. 14 is a timing chart of signals (drive switching operation) of each unit. This will be described with reference to these two figures. Reference numeral 11 denotes a U-phase drive signal generator. In this case, Vug, which is a U-phase drive signal, and a select signal for indicating and selecting which potential is used to drive the motor are input, and a drive signal for a switch group of the power converter is generated. Reference numerals 11a to 11c denote dead time generators for preventing a short circuit, and reference numerals 11d to f denote drive circuits for driving the elements. The select signal is supplied from a PWM control unit (not shown).

When the select signal is H (high), the pair of Tr21 and Tr22 is turned off, and Tr11 and Tr31 are alternately turned on and off according to the U-phase PWM signal Vug. Accordingly, the U-phase voltage Vu of the motor is a pulse voltage in which Vbh and 0V appear alternately. In this case, the electric power supplied to the motor is supplied from the battery 1 (Ph).
When the select signal is L (low), Tr11 is turned off, and the pair of Tr21 and Tr22 and Tr31 are alternately turned on and off according to the U-phase PWM signal Vug. Therefore, the U-phase voltage Vu of the motor is a pulsed voltage in which Vbm and 0V appear alternately. In this case, the electric power supplied to the motor is supplied from the battery 2 (Pm).
If the ratio of the time to set the select signal to H and the time to set it to L is changed, the ratio of the time for performing the above two operations can be changed. Therefore, the battery 1 and the battery 2 can be controlled by controlling the select signal. The ratio of the supplied electric power can be made into a desired value. The same applies to power running and regeneration.

FIG. 12 shows a timing chart of the simulation result when the select signal is switched from L to H (0 to 1) when the motor is performing the regenerative operation in the second embodiment. The select signal is switched from L to H at time t1, but both Ih, which is the current flowing to the battery 10, and Im, which is the current flowing to the battery 20, are in a state before the time t1 (a state where the select signal is L). The electric power is regenerated (charged) in both batteries. On the other hand, when the state is after time t1 (the select signal is in the H state), no current flows through the battery 20, and the current (Ih) flows only through the battery 10. As can be seen from this result, the power supplied to the two batteries can be adjusted by the select signal. By the way, when the select signal is in the L state, the power is returned not only to the battery 20 but also to the battery 10 because of dead time. In actual control, the time ratio of the select signal H / L is determined in consideration of the dead time. If the electric power supplied from each battery can be controlled to an arbitrary value, there is a feature that appropriate electric power can be used according to the state of the battery, for example, the charging state of each battery.
As described above, in this embodiment, the configuration of the power converter can be simplified, and the power supplied from the two batteries or the ratio of the power supplied to the two batteries can be set to a desired value. Furthermore, a plurality of batteries can be kept in an optimum charged state by the optimum distribution of the regenerative current.

Modification 1-2
Next, two modifications of the power conversion device using three-phase three-level, partly bidirectional switching (that is, partly using diodes) are shown.
FIG. 5 is a diagram showing a circuit configuration of the current converter according to the first modification of the present invention. As shown in the figure, FIG. 5 (this modification) and FIG. 3 (Embodiment 2) differ in the switch configuration and connection in the switch groups 31b, 32b, and 33b of each phase, and the high voltage side is set to a common potential. Only the switch on the common potential side of each phase uses a diode instead of the bidirectional switch, but other components (capacitors C1 and C2 are omitted in FIG. 5) are the same.
FIG. 6 is a diagram showing a circuit configuration of a current converter according to a second modification of the present invention. As shown in the figure, FIG. 6 (this variation) and FIG. 3 (Embodiment 2) are different in switch configuration and connection in the switch groups 31c, 32c, and 33c of each phase, and the batteries 10 and 20 are connected in series. Only the switch on the low potential side uses a diode instead of the bidirectional switch, but other components (capacitors C1 and C2 are also omitted in FIG. 6) are the same. In these modified examples, substantially the same effect as that of the above-described embodiment can be obtained, but details are omitted.

Third Embodiment As a third embodiment of the present invention, a power converter using three-phase four-level, only intermediate potential bidirectional switching will be described in detail. FIG. 7 is a diagram showing a circuit configuration of a current converter according to the third embodiment of the present invention. This embodiment is an example of a power converter that generates four potentials by setting the low voltage side of three batteries to a common potential, and generates a motor applied voltage from these potential voltages. The magnitude relationship among the voltage Vbsh of the third battery 10sh having the highest voltage, the voltage Vbh of the first battery 10 and the voltage Vbm of the second battery 20 is as follows.
Vbsh>Vbh> Vbm
In the case of this embodiment, the switch in the reverse direction of the switch connected to the maximum voltage potential and the switch connected to the minimum potential is a diode. With such a configuration, it is possible to apply all potential voltages to the motor while simplifying the configuration of the switch, and it is possible to secure a current path even during the dead time period. . In other words, in this configuration, the bidirectional switch (power element) is replaced with a switch (diode) with lower loss and lower cost, so that the opportunity for current to flow through the bidirectional switch is reduced, resulting in lower loss. It is possible to reduce the cost.

Fourth Embodiment A fourth embodiment of the present invention will be described in detail in which a three-phase, three-level, partly bidirectional switching power converter is applied to an actual two-power-source vehicle. FIG. 8 is a diagram showing a circuit configuration of a current converter according to the fourth embodiment of the present invention. This embodiment is an example applied to an automobile having two power sources of 42V system and 14V system, and the 14V system is a voltage generally used in vehicles. For example, since it is a power source for driving auxiliary equipment (lights, indoor equipment, etc.) of a vehicle, a power storage device having a relatively small load and a low potential of about 14V is used.
On the other hand, in recent automobiles, power consumption increases, and equipment with a large load such as a vehicle drive or an air conditioner compressor is sometimes mounted. In a 14V power supply system, the current flowing through the electric wire becomes too large. Vehicles having a higher voltage 42V power supply system are appearing. Such a vehicle has a system configuration in which, for example, a 42V power supply system is used for a heavy load and a 14V system is used for a medium / small load.

  The configuration of the power converter 30d in this embodiment is the same as that of the power converter of the second embodiment shown in FIG. Reference numeral 40 denotes a motor whose output shaft is connected to an output shaft of an engine (not shown). Reference numeral 1 denotes a 42V battery, and reference numeral 20 denotes a capacitor used as a 14V voltage source. L1 is various loads of 42V system. L2 is various loads of 14V system. The motor 40 is normally driven by an engine and operates as a generator. At that time, as described in the second embodiment, the generated power of the motor 40 is optimized for each battery by the switching configuration (31d, 32d, 33d) of the power converter 30d according to the state of the battery 10 and the battery 20. Can be supplied at a proper distribution ratio. That is, although not shown in the figure, a monitor for monitoring the state of each battery is provided, thereby supplying electric power with an optimum distribution ratio according to the state of charge of each battery, etc., so that the state of charge of each battery is optimized. It becomes possible to hold.

FIG. 9 is a diagram showing an example of a configuration of a power supply system of a conventional 42V vehicle. In the conventional configuration, a conventional power converter 80 is provided, and the generated power from the generator is a first 42V. After the battery 10 is charged, the required amount of power is converted to 14V by 70 DC-DC converters and supplied to the second battery 20 of 14V. Such a conventional configuration requires a DC-DC converter 70 that converts 42V to 14V. Since the DC-DC converter requires a coil, it is difficult to reduce the size and the loss also increases.
On the other hand, the present embodiment does not require a DC-DC converter, and since the generated power is directly distributed by the semiconductor switch, the size of the system can be greatly reduced, and the loss can be greatly reduced. Furthermore, it is possible to freely controls the power of 14V system with the power converter can be used a capacitor as a voltage source of 14V system can further make the system compact.

Fifth Embodiment A fifth embodiment of the present invention will be described in detail in which a three-phase, three-level, partly bidirectional switching power converter is applied to a series hybrid vehicle. FIG. 10 is a diagram showing functional blocks of a vehicle incorporating a current converter according to the fifth embodiment of the present invention. 10 and 20 are batteries. The output voltage Vbh of the battery 10 and the Vbm of the battery 20 have the following relationship.
Vbh> Vbm (3)
30A and 30B are the same as the power converter 30 of FIG. 3 described in the second embodiment. Reference numeral 90 denotes a generator connected to the engine, and reference numeral 40 denotes a motor that generates driving torque of driving wheels of a vehicle (not shown). As described in the second embodiment, the power converters 30A and 30B can arbitrarily set the power to and from the two batteries. The power converter 30 </ b> B connected to the motor 40 efficiently drives the motor 40 using the power of the two batteries of the battery 10 and the battery 20.

  On the other hand, the power converter 30A distributes the generated power of the generator to the battery 10 and the battery 20 according to the state of each battery. By doing so, it is possible to control both batteries to a desired battery state, for example, a desired state of charge (SOC), while driving the motor efficiently. When power converter 30A drives motor 6 with high efficiency using the voltage of battery 10, power converter 30A supplies power from battery 10 to power converter 30B in order to keep the SOC of battery 10 at a constant SOC. The same electric power as the electric power being supplied can be supplied to the battery 10.

In FIG. 11, the timing chart of the simulation result of this embodiment is shown. This is a simulation result when the motor is accelerating with the output torque of the drive motor 60 kept constant. Prior to time t1, since the motor rotation (Nmot) is low and the drive is possible at a low voltage, the drive is performed using the voltage of the battery 20 which is a low voltage battery. After the time t1, the rotation is high and the battery 10 is driven using the voltage of the battery 10 which is a high voltage battery. Prior to time t1, the current from the battery is supplied from the battery 20 (Im) and thereafter from the battery 10 (Ih). Although not shown in this figure, the SOC of each battery can be kept substantially constant by controlling the power converter 3 to supply substantially the same power as the power supplied from each battery.
As described above, in applications such as a series hybrid vehicle using two motors, the SOCs of the two batteries can be controlled to desired values while driving the motors with high efficiency.

Finally, the features and advantages of the present invention are summarized.
1. Using multiple power supply voltages, both motor efficiency and inverter efficiency can be improved.
-The voltage to be used can be switched (Vbh or Vbl) according to the motor applied voltage.
・ Harmonic current can be reduced by 3-level drive.
2. Input / output power of multiple power supplies can be controlled independently.
・ If it is a 42V car, it can be charged with a 14V power supply without a step-down DC / DC converter.
It is possible to transfer any power from one of the power sources to the other power source.
3. Compared to a matrix converter, a step-up DC / DC converter + inverter, and a conventional three-level inverter, the configuration is simple.

Although the principle of the present invention has been described in various embodiments in the present specification, those skilled in the art can make various modifications and changes to the present invention based on the present disclosure, and these are also included in the present invention. Please note that
For example, although IGBT is given as an example of the switching element, the present invention may use a known element such as another power element such as a GTO or a transistor.
For example, in the fifth embodiment, a configuration in which two batteries are used has been described. However, the battery is only on the high voltage side, the low voltage side is a capacitor, and the charge / discharge amount is controlled to be controlled to an arbitrary voltage. Is also possible. Furthermore, in the fifth embodiment, the configuration using only one motor has been described. However, a configuration of a plurality of motors can be used, and in this case, the variable width of the power supplied to the two voltage lines can be increased. Similarly, in the second embodiment, the configuration using two batteries has been described. However, the battery is only on the high voltage side, the low voltage side is a capacitor, and the charge / discharge amount is controlled to be controlled to an arbitrary voltage. It is also possible.

It is a figure which shows the typical circuit structure of the conventional 3 level inverter. It is a figure which shows the circuit structure of the current converter by the 1st embodiment of this invention. It is a figure which shows the circuit structure of the current converter by the 2nd embodiment of this invention. It is a figure explaining the flow of the electric current at the time of a dead time in the 2nd embodiment of the present invention. It is a figure which shows the circuit structure of the current converter by the 1st modification of this invention. It is a figure which shows the circuit structure of the current converter by the 2nd modification of this invention. It is a figure which shows the circuit structure of the current converter by the 3rd embodiment of this invention. It is a figure which shows the circuit structure of the current converter by the 4th embodiment of this invention. It is a figure which shows an example of a structure of the power supply system of the conventional 42V vehicle. It is a figure which shows the functional block of the vehicle incorporating the current converter by the 5th embodiment of this invention. The timing chart of the simulation result of the 5th embodiment is shown. It is a timing chart of a simulation result when a select signal is changed from L to H when the motor is performing a regenerative operation in the second embodiment. It is a figure which shows the structure of the U-phase part of the power converter of a 2nd embodiment, and its drive signal generation part. FIG. 14 is a timing chart of signals (drive switching operation) of each unit illustrated in FIG. 13. FIG. It is a figure explaining the flow of an electric current when the switch of the highest electric potential is ON in the 2nd embodiment. It is a figure explaining the flow of an electric current when the switch of the 2nd highest electric potential is on in the 2nd embodiment. It is a figure explaining the flow of an electric current when the switch of the lowest electric potential is on in a 2nd embodiment. It is a timing chart which shows the output voltage waveform of the U phase in a 1st embodiment. It is a figure which shows the state of the gate signal of IGBT which comprises the switch group of the U phase in a 1st embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 1st battery 10sh 3rd battery 20 2nd battery Vbh Battery 1 voltage Vbm Battery 2 voltage 30 Power converter 40 AC motor C1, C2 Capacitors 31, 32, 33 U phase, V phase, W phase Switch group Tr11-92 switch (IGBT)
30a Power converter 31a, 32a, 33a U-phase, V-phase, W-phase switch group D1-9 Diode 30b, 30c Power converter 31b, 32b, 33b U-phase, V-phase, W-phase switch group 31c, 32c, 33c U-phase, V-phase, W-phase switch group L1, L2 Load Drive motor 60
70 DC-DC converter 80 Conventional power converter 30A, 30B Power converter 90 Generator

Claims (7)

A power conversion device that generates an AC voltage waveform from a DC voltage source output voltage as a pulse voltage,
The DC voltage source includes a voltage source output unit that outputs three or more potentials including a common potential,
Each of the power converters includes switching means for connecting to one of the three or more potentials and applying a voltage to the output of the power converter,
The switching means generates the pulse voltage by connecting to each of the three or more potentials and controlling an on / off pulse width.
The power converter characterized by the above-mentioned. The power conversion device according to claim 1,
When the voltage source output unit arranges the potential between the output units in order of magnitude, the potential difference with the potential of the adjacent output unit is set to a different magnitude,
The power converter characterized by the above-mentioned. In the power converter device according to claim 1 or 2,
The AC voltage waveform is a multiphase AC voltage waveform and is a waveform for driving a multiphase AC motor.
The power converter characterized by the above-mentioned. In the power converter device according to any one of claims 1 to 3,
The switching means controls the input / output power amount of each DC voltage source of the voltage source output unit. In the power converter device according to any one of claims 1 to 4,
At least one of the DC voltage sources is a capacitor;
The power conversion device according to claim 1, wherein In the power converter device according to any one of claims 1 to 5,
A plurality of sets including the motor and the power converter are provided,
The DC voltage source that supplies power to these power converters is shared by the plurality of power converters,
The power converter characterized by the above-mentioned. A dual power system vehicle equipped with the power conversion device according to any one of claims 1 to 6,
The DC voltage source includes two DC voltage source means having different voltages,
The higher voltage of the DC voltage source means is a high load battery for driving a motor.
A dual power system vehicle characterized by the above.

Images