JPH04165901A - Power converter for electric automobile - Google Patents

Abstract

PURPOSE:To protect a fuse from blow-out by switching between a converter for converting a high DC voltage into a low DC voltage and an inverter for producing an AC voltage through a resistor for suppressing surge current flowing into an input side capacitor with a predetermined timing. CONSTITUTION:Upon turn ON of an ignition key (not shown), battery 10 voltage is fed through the resistance R' of a relay 24b to a capacitor C2 and a DC/DC converter 22, under control of an ECU 16, and a contact RY1 is closed with a slight time lag to charge an auxiliary battery 20 so as to energize an auxiliary machine 18. When an ignition key is turned to ST, contact RY2 of a relay 24a is closed and a voltage is fed from the main battery 10 through a resistor R to a capacitor C1 and an inverter 12 while at the same time the contact RY1 is opened. Subsequently, a contact RY3 is closed with a predetermined time lag followed by closure of the contact RY1 with a predetermined time lag. According to the constitution, an excessive surge current is prevented from flowing from the capacitor C1 to the capacitor C2 and a fuse 28 is protected against fusion.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an electric automatic military power converter that converts a DC voltage output from a main battery into an AC voltage and supplies it to a motor, particularly at the contacts of the power input section. Concerning opening/closing control and circuit improvement.

[Background Art] An electric vehicle is a vehicle that is equipped with a battery and a motor, and runs by driving the motor with electric power from the battery. FIG. 5 shows the configuration of a conventional electric vehicle, particularly the configuration of its power converter. The device shown in this figure is a modification of the device described as the prior art in Japanese Patent Application No. 16576/1993, with two fuses added.

The device shown in this figure includes a main battery 10 that outputs a predetermined voltage, for example, a DC voltage of 200V. The main battery 10 is connected to an inverter 12 that includes switching elements and control elements according to the number of phases, and the inverter 12 is further connected to a motor 14 that is a three-phase induction motor.

The inverter 12 is a circuit that converts the DC voltage output from the main battery 10 into three-phase alternating current.

Therefore, the motor 14 is driven to rotate by receiving the alternating current voltage from the inverter 12.

Further, in this figure, an ECU 16 that controls the operation of the inverter 12 is shown. The ECU 16 controls the torque generated in the motor 14 by controlling a conversion function related to the inverter 12.

On the other hand, electric vehicles are usually equipped with a device called an electrical auxiliary device. In this figure, electrical auxiliary equipment is indicated by ]8, and includes, for example, a pump related to electrolyte circulation of the main battery 10, a lamp related to front lighting, etc.

The voltage for driving this electrical auxiliary machine is, for example], 4
Since the voltage is different from the voltage output from the main battery 10, the auxiliary battery 20 is used for driving.

The auxiliary battery 20 is designed to output a DC voltage of, for example, 14 V in order to drive the electrical auxiliary machine 18 . The auxiliary battery 20 has a smaller capacity than the main battery 10 and is charged using the output voltage of the main battery 10. Because of this charging, in Figure 5,
A DC/DC converter 22 is employed.

That is, the main battery-0 is connected to the input terminal of the DC/DC converter 22, and the auxiliary battery 20 and the electrical auxiliary machine 1 are connected to the output terminal of the DC/DC converter 22.
8 are connected in parallel. DC/DC converter 22
Basically, it has a built-in device that converts DC voltage to AC voltage, a transformer, and a rectifier, and the main battery 10
This is a device that converts the output voltage of the auxiliary battery 20 into a voltage suitable for charging the auxiliary battery 20. Therefore, the DC/DC converter 22
converts the voltage output from the main battery-0 to charge the auxiliary battery 20 and drive the electrical auxiliary machine 18.

On the other hand, in this device, inverter 2 and DC/
Input capacitors C and C2 are used to stabilize the operation of DC converter 22. The input capacitor CI is provided in parallel on the input side of the inverter 2, and has a capacitance of about 20,000 μF. Human power capacitor C2 of about 10000μF
are similarly provided in parallel on the input side of the DC/DC converter 22. Therefore, even if the current value to be supplied to the motor 4 or the electrical auxiliary equipment 18 changes, the change in the voltage supplied to the inverter 2 and the DC/DC converter 22 is alleviated by the input capacitors C and C2. Therefore, the inverter 2 and the DC/DC converter 22 can operate stably.

Furthermore, a relay 24 is provided between the input capacitors C and C2 and the main batch 10.

This relay 24 is a relay controlled by the ECU 16, and is means for controlling operations when starting and stopping the electric vehicle.

Among the relays 24, the input capacitor C1 and the main battery 1
The portion 24a provided between the two contacts RY2 and
and RY3. Both contacts RY2 and RY3 are connected in parallel, and one contact RY2 has 10
An auxiliary charging resistor R of about 0Ω is connected.

On the other hand, the portion 24b provided between the input capacitor C2 and the main battery -0 has a contact RYI and a resistor R'. Contact RYI and resistor R' are connected in parallel with each other. The resistance R'' is the main battery] 0 and D C/D C
This resistor is used to protect against excessive charging current when the converter 22 is connected, and has a resistance value of several hundred ohms. That is, if the connection is made without the resistor R' when the contact RYI is not turned on when manufacturing the device, a large current will flow due to the rapid charging of the input capacitor C2. Resistor R' prevents this.

Note that 26 is a fuse that blows when the inflow current from the main battery 10 to the inverter 12 and input capacitor C1 becomes larger than a predetermined value (that is, in an overcurrent state); and a fuse that melts when an overcurrent condition occurs due to the inflow of current into the input capacitor C2. The former has a capacity of 400A, for example, and the latter has a capacity of 2OA.

FIG. 6 shows the operation of the relay 24 in this conventional example. The relay 24 is controlled according to the set position of an ignition (IG) key operated by the operator of the electric vehicle. The IG key usually has off, on, and starter (ST) setting positions for harmony with gasoline AT vehicles.

That is, in this conventional example, when the operator turns the IG key from off to on, the ECU 16 turns on contact RYI in response. Then, voltage is supplied from the main battery 10 to the input capacitor C2 and the DC/DC converter 22 via the contact RYI. As a result, D C/
When the operation of the DC converter 22 is started, the ECU 1
The auxiliary battery 20 that supplies operating power to the auxiliary battery 20 starts operating stably, and subsequent operations are stably executed.

Next, when the pilot sets the IG key to the ST position, the EC
In response, U16 turns on contact RY2. Then, the main battery 10, the input capacitor C1, and the input capacitor 12 are connected through the resistor R, and the input capacitor C1 is charged with the following constant RC1.

When connected in this state, the inverter 12 is driven via the resistor R, resulting in problems such as heat generation. Therefore, when charging of the input capacitor C1 is almost completed, that is, after a predetermined period of time, for example, about 1 to 2 seconds has passed since the IG key is in the ST position, the ECU
16 turns on contact RY3. This time is set in consideration of the operational feel. Then, the main battery 10, the input capacitor C1, and the inverter 12 are short-circuited, and a normal operation is started in which no heat is generated and the electric power is used effectively.

[Problems to be Solved by the Invention] However, in the conventional device, there is a problem in that an inrush current flows when the relay is operated, and in particular, the fuse on the DC/DC converter side melts.

For example, as shown in FIG. 6, when contact RY2 is turned on, an inrush current occurs as charging of input capacitor C1 begins. This rush current is mainly supplied from the main battery 10 and does not lead to melting of the fuse 28 on the DC/DC converter 22 side.

However, if contact RY3 is subsequently turned on, normally 100
An input capacitor C2 having a capacitance of about 00 μF is short-circuited to the input capacitor C1 via a contact RYI, fuses 28 and 26, and a contact RY3. Then, an inrush current having an excessive peak corresponding to the voltage difference between the input capacitors C1 and C02 flows into the fuse 28. This rush current often reaches a value that causes the fuse 28 to melt.

If the fuse 28 melts and is damaged, the subsequent DC/D
The C converter 22 will no longer be able to operate, and the fuse 28 will need to be replaced. However, even if the fuse 28 is replaced and the apparatus is started up again, there is a possibility that the fuse 28 will be repeatedly melted and damaged. In order to prevent such a malfunction, it is possible to replace the fuse 28 with a fuse with a larger current capacity, but if this is done, a failure or the like may occur in the DC/DC converter 22 or the auxiliary battery 20, etc. In this case, it becomes difficult to protect the configuration of the main battery 10 and the inverter 12 from this failure.

Furthermore, in order to suppress the rush current, it is better to reduce the auxiliary charging resistance R. However, if this is done, the charging current of the input capacitor C1 becomes large, so the shapes of the contact RY2 and the resistor R become large.

The present invention has been made with the aim of solving these problems, and it is possible to suppress (suppress) the inrush current generated on the input side of the inverter and DC/DC converter without increasing the size of the device. It is an object of the present invention to provide a device in which fuses on the DC/DC converter side do not melt unless a load abnormality or the like truly occurs.

[Means for Solving the Problems] In order to achieve such an object, the electric vehicle power converter of the present invention has the following configuration. In other words, there is an inverter that drives the motor by converting the DC voltage output from the main battery into an AC voltage with a predetermined number of phases, an inverter-side input capacitor connected in parallel to the input terminal of the inverter, and an AC voltage with a predetermined number of phases. D converting the output DC voltage into a DC voltage of a different value
A fuse that is installed between the C/DC converter and the main battery and melts when the current exceeds a certain value, and a DC/DC
A DC/DC converter side input capacitor connected in parallel to the input end of the converter, a first switching means provided between the fuse and the DC/DC converter side input capacitor, and a first switching means connected in parallel to the first switching means. a current limiting resistor, a second switching means provided between the main battery and the inverter side input capacitor, a supplementary heavy duty resistor connected in series to the second switching means, and a supplementary heavy duty resistor connected to the second switching means and the supplementary heavy duty resistor. Close the third switching means connected in parallel and the first switching means to charge the input capacitor on the DC/DC converter side, then close the switching means in clause 2 to charge the input capacitor on the inverter side, and then After a predetermined time has elapsed, the second switching means is opened, and when the third switching means is closed, at least the first switching means is opened, thereby reducing the fuse, the current limiting resistor, and the DC/DC converter side input capacitor. and opening/closing control means for connecting the two in series.

[Function] In the electric vehicle power converter of the present invention, the following opening/closing control is executed when the device is driven. Masu,
The first opening/closing means is closed. The first opening/closing means is a DC
This is an opening/closing means provided between the input capacitor on the /DC converter side and the fuse, and when this is closed, the two are short-circuited and charging of the input capacitor is started.

After this, the second opening/closing means is closed. As a result, the auxiliary charging resistor is interposed between the main battery and the inverter-side input capacitor. Therefore, the capacitor is charged with a time constant determined as the product of the resistance value of the charging resistor and the capacitance of the input capacitor on the inverter side.

Next, the second opening/closing means is opened and the third opening/closing means is closed. At this time, at least the first opening 12-closing means is opened. Then, the fuse, current limiting resistor, and DC/DC converter side input capacitor are connected in series.

At this time, the third opening/closing means is closed, resulting in a short circuit between the main battery, the inverter-side input capacitor, and the inverter. In this state, the inverter can drive the motor by effectively utilizing the DC voltage supplied from the main battery.

Further, when the second switching means is opened, a current limiting resistor is interposed between the DC/DC converter side input capacitor and the fuse. Therefore, melting of the fuse due to discharge of the input capacitor on the DC/DC converter side is prevented.

[Examples] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Note that the same components as those of the conventional example shown in FIGS. 5 and 6 are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 1 shows the operation of the relay 24 of the electric vehicle power converter according to the first embodiment of the present invention. Since this embodiment has a device configuration similar to that of the conventional example shown in FIG. 5, only the operation of the relay 24 relating to its characteristics will be described below.

Among the operations of the relay 24 in this embodiment, the operation of turning on the contact RYI when the G key is turned on is the same as in the conventional example. The difference between this embodiment and the conventional example is that when the IG key is set to ST, the contact RY2 is turned on and the contact RYI is turned off at the same time. The contact RY3 is turned on after a predetermined period of time elapses after the contact RY2 is turned on, as in the conventional example, and the contact RYI is turned on again after a predetermined period of time, for example, Q, about 5 seconds has elapsed since the contact RY3 was turned on. .

As a result of such operation, in this embodiment, DC/D
This prevents the fuse 28 from melting due to the discharge of the input capacitor C2 on the CC/type controller 22 side. That is, contact RY
2 is turned on, the contact RY] is turned off, so the current flowing into the fuse 28 at this time is caused by the resistance R- of about several hundred ohms.
For example, it is limited to 2A or less. In addition, contact RY
] must be turned on again in order for the DC/DC converter 22 to operate properly, but this operation must be performed after a certain period of time has passed since the contact RY3 was turned on, that is, when the inverter 12 side This is done after the input capacitor C1 of
Therefore, the current flowing into 8 will not become excessive. Therefore,
This prevents the fuse 28 from melting.

Furthermore, the resistor R- that limits the current can also be used as a resistor conventionally used to prevent rapid charging during connection. Therefore, the configuration is not particularly complicated.

FIG. 2 shows the configuration of a power converter for an electric vehicle according to a second embodiment of the present invention, in particular, D C/D C of the relay 24.
The configuration of a portion 24b on the converter 22 side is shown.

In this embodiment, a contact RY4 and a diode D1 are provided in parallel with the resistor R- and the contact RY1.

The current capacity of the diode D1 is, for example, 5 to IOA.

In this embodiment, the control timing of the relay 24 by the ECU 16 is as shown in FIG.

That is, when the IG key is turned on, the ECU 6 turns on the contact RY4. Then, the main battery ] 0 and D C
/DC converter 22 and human power capacitor C2 are connected via diode D1.

Next, when the IG key is set to ST, the contact RY
2 is turned on. In this state, the input capacitor C1 is charged as in the conventional example and the first embodiment. At this time, since conduction through the contact RY4 is prohibited by the diode D1, a resistor R' is interposed between the fuse 28 and the input capacitor C2. This resistance R'
As a result, the current flowing into the fuse 28 is suppressed.

Next, after a predetermined period of time has passed after connection RY2 is turned on, the ECU
16 turns on contact RY3. This causes a short circuit between the main battery 10 and the input capacitor C1 on the inverter 12 side.

Next, the ECU 16 turns on the contact RYI after a predetermined period of time, for example about 0.5 seconds, has elapsed since the contact RY3 was turned on. At this time, since the potential difference between input capacitors C1 and 02 has already become small, input capacitor C2 flows to fuse 28 by turning on contact RYI.
The discharge current becomes smaller. Therefore, in this embodiment as well, generation of rush current that would melt the fuse 28 is prevented.

FIG. 4 shows the configuration of the electric vehicle power converter according to the third embodiment of the present invention, particularly the DC/DCC/type of the relay 24.
The configuration of the portion 24b on the data 22 side is shown. The embodiment shown in this figure has a configuration in which the resistor RYI in the second embodiment is omitted.

The control timing of this device is similar to the control timing of the conventional example shown in FIG. However, the contact RYI in FIG. 6 should be read as RY4.

In this embodiment, when the IG key is turned on, contact R
Y4 is turned on, and main battery 10 is connected to DC/DC converter 22 and input capacitor C2 via fuse 28 and contact RY4.

Then, when the IG key is set to ST, E
CU 1.6 turns on contact RY2 and charging of input capacitor C1 via resistor R begins.

At this time, the current flowing into the fuse 28 from the input capacitor C2 is limited by the resistor R'.

When the contact RY3 is turned on after the contact RY2 is turned on, the main battery 10 is short-circuited with the inverter 12 and the input capacitor C1 via the fuse 26 and the contact RY3, but at this time, the DC/DCC/type Since the resistor R- is present in the portion 24b on the side of the input capacitor 22, the fuse 28 is
The inflowing current is limited by this. Therefore, in this embodiment as well, melting of the fuse 28 due to discharge of the input capacitor C2 is prevented. Note that this embodiment uses a relatively small capacitance D in consideration of the power loss caused by the diode D2.
It is preferable to apply this when using the C/DC converter 22.

[Effects of the Invention] As explained above, according to the present invention, the current flowing to the fuse due to discharge of the input capacitor on the DC/DC converter side is limited by the current limiting resistor, so that the fuse is melted due to the current. Truly DC
The function of the fuse, which blows only when an abnormality occurs in the /DC converter or its load, can be properly performed, and a small and highly reliable device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a timing diagram showing the operation of the relay in the electric vehicle power converter according to the first embodiment of the present invention, and FIG. 2 is a timing diagram showing the operation of the relay in the electric vehicle power converter according to the second embodiment of the present invention. A circuit diagram showing a partial configuration, FIG. 3 is a timing diagram showing the operation of the second embodiment, and FIG. 4 shows a partial configuration of an electric vehicle power converter according to a third embodiment of the present invention. The circuit diagram, FIG. 5 is a diagram showing the configuration of the electric vehicle power converter according to the conventional example and the electric vehicle power converter according to the first embodiment of the present invention, and FIG. 6 is the operation of the conventional example. FIG. 10... Main battery 12... Inverter 14... Motor 16... ECU 18... Electrical auxiliary equipment 20... Auxiliary equipment battery 22... DC/DC converter 24... Relay 28... - Fuses C1, C2... Input capacitors R, R-... Resistors RYI, RY2. RY3. RY4...Contact D1
··· diode

Claims (1)

[Scope of Claims] An inverter that drives a motor by converting a DC voltage output from a main battery into an AC voltage of a predetermined number of phases and supplying the same; an inverter-side input capacitor connected in parallel to an input terminal of the inverter; , a fuse that is installed between the main battery and the DC/DC converter that converts the DC voltage output from the main battery into a DC voltage of a different value, and that melts when the current exceeds a predetermined value; and the input of the DC/DC converter. DC/
DC converter side input capacitor, fuse and DC/
A first switching means provided between the DC converter side input capacitor, a current limiting resistor connected in parallel to the first switching means, and a second switching means provided between the main battery and the inverter side input capacitor. a auxiliary charging resistor connected in series to the second switching means; and a third auxiliary charging resistor connected in parallel to the second switching means and the auxiliary charging resistor.
the first switching means is closed to charge the DC/DC converter side input capacitor, the second switching means is closed to charge the inverter side input capacitor, and after a predetermined period of time, the second switching means is closed to charge the inverter side input capacitor. By opening the switching means and opening at least the first switching means when closing the third switching means, the fuse, the current limiting resistor, and the DC/DC
A power converter for an electric vehicle, comprising: opening/closing control means that connects a converter-side input capacitor in series;