JPH0540645Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an inverter circuit for an electric vehicle, and particularly relates to an improvement in the configuration of switching elements of an inverter circuit.

[Prior Art] Electric vehicles are being researched as pollution-free vehicles that do not produce harmful exhaust gases, and some are already at the stage of practical application.

Early electric vehicles used DC motors as a drive source because they were easy to control, but brushes and other parts of these DC motors were difficult to maintain, so in recent years, easy-to-maintain inverters have been used as drive sources for electric vehicles. Controlled alternating current motors have come into use.

Here, inverter control of the AC motor is generally performed by converting DC power from a battery into three-phase AC power by an inverter circuit consisting of six switching elements and supplying the desired power to the AC motor. .

FIG. 4 shows a basic circuit of such a conventional inverter. An inverter circuit 12 is connected to a battery 10, and three-phase AC power is supplied from the inverter circuit 12 to a vehicle drive motor 14. The inverter circuit 12 includes six transistors.
U ₊ , U _- , V ₊ , V _- , W ₊ , W _- and six feedback diodes D ₁ connected in antiparallel to each transistor.
~D Consists of ₆ .

This conventional inverter circuit only has the function of converting battery voltage into three-phase alternating current, and is used to control only the motor for driving the vehicle.

Therefore, due to the demand for effective use of batteries as a characteristic of electric vehicles, when battery power is used as an external load power source other than the drive motor, for example,
When used as a power source for general electric equipment in areas where commercial power is not available, an inverter circuit for external loads is required in addition to the inverter circuit for the drive motor described above.

That is, it is necessary to separately provide an inverter circuit for converting battery power into single-phase AC power and supplying it to an external load.

Figure 5 shows two types for motor drive and external load.
A conventional circuit configuration is shown in which two inverters are provided, and the battery 10 includes a vehicle drive motor 14.
In addition to the three-phase output inverter 12 that supplies AC power to the external load 16, a single-phase output inverter 18 is connected to supply single-phase AC power to the external load 16.
Switch 20 for switching both inverter circuits
It is configured to be conducted at

[Problems to be solved by the invention] In the conventional inverter circuit described above, when battery power is also used as an external load power source, the inverter circuit 12 including six switching elements
In addition, an inverter circuit 18 for an external load power supply including four switching elements is required.

That is, at least 10 switching elements are required, and an inverter circuit consisting of two components must be mounted on the vehicle.

Therefore, there have been problems in that the space and weight occupied by the inverter circuit are large, and the cost is also high.

Furthermore, in the conventional configuration with two inverter circuits, a changeover switch 20 is provided to prevent malfunction and ensure safety, but since this changeover switch is a switch for the vehicle drive motor,
It had to be a large-capacity switch that could tolerate the large power of the battery 10, resulting in high costs and problems with its reliability.

The present invention was developed in view of the above problems, and its purpose is to make it possible to supply AC power to both the drive motor and external load using eight switching elements, thereby reducing space and cost. An object of the present invention is to provide an inverter circuit for an electric vehicle that can perform the following functions.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes six switching elements that convert battery DC power into three-phase AC power, and any one of the six switching elements. Two switching elements are provided which are combined with two one-phase switching elements to convert the battery DC power into single-phase AC power, and when the vehicle is running, the six switching elements are switched to provide power for driving the vehicle. Three-phase AC power is supplied to the motor, and when the vehicle is stopped, the combined four-phase
The present invention is characterized in that it is possible to supply single-phase AC power to an external load by switching the switching elements.

[Function] According to the above configuration, when the vehicle is running, battery power is converted into three-phase AC power by switching six switching elements out of a total of eight switching elements constituting the inverter circuit,
Supplies the drive motor.

When using general electrical equipment when the vehicle is stopped, the two switching elements provided for external loads and the two switching elements for one-phase output among the six switching elements for three-phase output are switched off. By switching the four switching elements combined, the battery power is converted into single-phase alternating current and supplied to an external load.

Therefore, the inverter circuit composed of eight switching elements can supply AC power to both the drive motor and the external load.

[Embodiment] FIG. 1 is a diagram showing a preferred embodiment of the inverter circuit for an electric vehicle according to the present invention, and the same elements as in the conventional example shown in FIGS. 4 and 5 are given the same reference numerals. are doing.

The inverter circuit 30 according to this embodiment is composed of eight transistors (switching elements) and eight feedback diodes connected antiparallel to these transistors, among which six transistors U ₊ , U _- , V ₊ , V _- , W ₊ , W _- constitute a three-phase inverter section 13, and four transistors U ₊ , U _- , Z ₊ , Z _- constitute a single-phase inverter section 22. It is configured.

That is, the two transistors Z ₊ and Z _- are newly added for single-phase alternating current, and the transistors U ₊ and U _- which are combined with these to form the single-phase inverter section 22 are It is controlled so as to function both as a switching element of the single-phase inverter section 22 and as a switching element constituting the three-phase inverter section 13.

Switching control of each transistor is performed by an inverter drive circuit 34 based on a signal sent from a control device 32.

First, when the vehicle is running, the three-phase inverter section 13
The vehicle drive motor 14 is controlled by the switching control of
Supplies 3-phase AC power to

At this time, transistors Z ₊ and Z _- are always in an off state.

Next, when the external load 16 is used when the vehicle is stopped, single-phase AC power is supplied to the external load 16 by switching control of the single-phase inverter section 22.

At this time, transistors V ₊ , V _- , W ₊ , and W _- are all in an off state.

FIG. 2 is a drive system diagram of the single-phase inverter section 22 when supplying single-phase AC power to an external load, and shows an example of the switching pattern of each transistor U ₊ , U _- , Z ₊ , Z _- . has been done.

When an off signal is sent to transistor Z ₊ and transistor U _- , transistor U ₊ ,
A predetermined on signal is sent to Z _- , and the transistor
When an off signal is sent to U ₊ and transistor Z _- , a predetermined on signal is sent to transistor Z ₊ and transistor U _- and a sine wave PWM
control is in place.

According to this embodiment, an inverter circuit consisting of eight transistors is equivalent to separately providing a three-phase output inverter circuit consisting of six transistors and a single-phase output inverter circuit consisting of four transistors. Since two transistors and a drive circuit for the transistors are not required, the space and weight required for the inverter circuit can be reduced, and costs can be reduced.

Further, FIG. 3 shows an example of a control circuit using an accelerator off signal and an AC motor off signal to prevent malfunctions in switching between the three-phase inverter section 13 and the touch single-phase inverter section 22.

Eight AND gates 40 corresponding to each transistor are provided between the control device 32 and the inverter drive circuit 34, and an inverter control signal from the control device 30 is input to one terminal of each AND gate. .

The other terminal of the AND gate corresponding to the transistors W ₊ , W _- , V ₊ , V _- receives a motor drive off signal 44 from a connector box 42 for an external load.
is supplied.

When the drive motor 14 is off, the Lo signal is sent; when the drive motor 14 is on, the Lo signal is sent.
A Hi signal is sent.

Therefore, transistors W ₊ , W _- , V ₊ , and V _- are controlled by inverter drive circuit 34 so that switching is performed only when drive motor 14 is in the on state.

Further, an accelerator off signal 48 based on depression of the accelerator 46 is supplied to the other ends of the AND gates corresponding to the transistors Z ₊ and Z _- .

A Hi signal is supplied when the accelerator 46 is not depressed, that is, when the vehicle is not running, and a Lo signal is supplied when the accelerator 46 is depressed, that is, when the vehicle is running.

Therefore, transistors Z ₊ and Z _- are switched only when the vehicle is stopped.

Transistors U ₊ and U _- are 3-phase inverter section 1
The transistors U + and U are used together as switching elements for both the transistor 3 and the single-phase inverter section 22, and switching control needs to be performed both when _driving the motor 14 and when supplying power to an external load. _- corresponding to AND gate 40
A voltage of 5V is always applied to the other terminals as a Hi signal.

In addition, when using the three-phase inverter section 13,
Transistors Z ₊ and Z _- are in the off state (non-conducting state)
is maintained, and when using the single-phase inverter section 22,
Transistors V ₊ , V _- , W ₊ , and W _- are controlled to remain off.

By using the control of the inverter drive circuit 34 by the AND gate 40 based on the motor drive off signal 44 and the accelerator off signal 48, the three-phase inverter section 13 and the single-phase inverter section 2
It is possible to prevent malfunctions in the switching of item 2 and eliminate the need for a changeover switch.

[Effects of the invention] As explained above, according to the inverter circuit for an electric vehicle according to the present invention, one inverter circuit consisting of eight switching elements can achieve the following effects.
Since battery power can be converted to both 3-phase AC power and single-phase AC power, two switching elements and their drive circuits are not required, and there is no need to provide a two-component inverter circuit. disappears.

This makes it possible to reduce the space and weight required for the inverter circuit, as well as reduce costs.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a preferred embodiment of the present invention;
FIG. 2 is a drive system diagram of the switching elements of the single-phase inverter section in the embodiment, FIG. 3 is a circuit diagram for controlling switching of each inverter section, and FIG.
The figure is a circuit diagram of a conventional three-phase AC output inverter, and FIG. 5 is a schematic diagram of a conventional device provided with two inverter circuits, one for motor drive and one for external load. 10... Battery, 12... Three-phase output inverter, 13... Three-phase inverter section, 14... Vehicle drive motor, 16... External load, 18... Single-phase output inverter, 20... Changeover switch, 22 …
...Single-phase inverter section, U, V, W, Z...transistor, D...feedback diode, 32...control device, 34...inverter drive circuit.

Claims (1)

[Claims for Utility Model Registration] Six switching elements for converting battery DC power into three-phase AC power, and two switching elements for any one phase among the six switching elements, Two switching elements are provided for converting DC power into single-phase AC power. When the vehicle is running, three-phase AC power is supplied to the vehicle drive motor by switching the six switching elements, and when the vehicle is stopped, three-phase AC power is supplied to the vehicle drive motor. , said combined 4
An inverter circuit for an electric vehicle, characterized in that it is possible to supply single-phase AC power to an external load by switching multiple switching elements.