JPH04275002A - Charger for electric automobile - Google Patents

Abstract

PURPOSE:To charge a main battery with a current lower than the allowable current of the components of inverter even when the voltage of the main battery is lower than the peak value of AC power supply voltage. CONSTITUTION:A current limiting resistor 30 is connected between a main battery 10 and an inverter 12 or between the inverter 12 and an AC power supply terminal. 18. The resistor 30 limits the current when the peak value of the output voltage from an AC power supply connected with the AC power supply terminal 18 is higher than the voltage of the main battery 10. When the voltage of the main battery 10 exceeds the peak voltage elevated through charging under current limitation, the resistor 30 is short-circuited and the charging operation is carried out in normal regenerative mode. Consequently, charging operation can be carried out even when the main battery 10 is in perfectly discharged state and the charging current can be set lower than the allowable current of each component.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric vehicle charging device that takes in an alternating current voltage from an input terminal for an alternating current power supply, rectifies it with an inverter, and charges a main battery.

0002

2. Description of the Related Art Conventionally, motors such as induction motors have been used as drive sources for electric vehicles. An alternating current is required to drive an induction motor, and this alternating current is generally generated by an inverter.

FIG. 5 shows the configuration of a conventional electric vehicle drive device. The device shown in this diagram includes a main battery 10 that outputs a predetermined DC voltage, and an inverter that converts the DC voltage output from the main battery 10 into an AC current of a predetermined number of phases (three phases in this diagram) and outputs the AC current. 12
A motor 14, which is an induction motor driven by an alternating current output from the inverter 12, and a control device 16 that drives and controls the motor 14 by controlling on/off of switching elements (transistors) that constitute the inverter 12. It consists of That is, main battery 1
The DC voltage output from the motor 1 is converted into an AC current by the inverter 12 under the control of the control device 16.
4. The control device 16 drives the inverter 12 according to a drive command supplied from an accelerator or the like, and performs vector control of the current supplied to the motor 14.

[0004] The device shown in this figure also operates the main battery 10 by inputting AC voltage from the AC power supply terminal 18.
It has a charging function. That is, JP-A-59-
It is equipped with a charging function disclosed in Japanese Patent No. 61402 and the like.

The main battery 1 is
When performing zero charging, the control device 16 turns off the switch 20 in response to a predetermined charging command. switch 20
is a switch provided between the output side of the inverter 12 and the motor 14, and when this switch 20 is turned off, the main battery 10, the inverter 12, and the motor 14 are disconnected. The AC power supply terminal 18 is provided on the output side of the inverter 12, for example between the U phase and the V phase, and the control device 16 performs PWM control on the switching elements of the U phase and V phase. Through this PWM control, the U-phase and V-phase of the inverter 12 function as a step-up rectifier circuit, and the output of the AC power supply connected to the AC power supply terminal 18 is a voltage rectified through the reactor 22 and the inverter 12. This will be applied to the main battery 10 as follows. Such an operation, that is, the inverter 12
The mode in which the main battery 10 is charged using
This is called regeneration mode.

As described above, in the past, it was possible to drive the motor 14 using the output voltage of the main battery 10, and it was also possible to charge the main battery 10 by using the inverter 12 in the regeneration mode. .

[0007]

[Problems to be Solved by the Invention] However, in conventional devices, even if the inverter is used in regeneration mode to charge the main battery, if the voltage of the AC power source is higher than a certain level, it becomes difficult to control the charging operation. The problem arises.

For example, when the peak value of the voltage of the AC power source is higher than the voltage value of the main battery, the diodes connected in antiparallel to the switching elements constituting the inverter turn on, causing the inverter to operate as a bridge rectifier. Become. As a result, depending on the PWM control by the control device,
The current supplied to the main battery cannot be controlled. In addition, if the difference between the peak value of the AC power supply voltage and the output voltage of the main battery becomes larger than a certain level, the tolerance of each semiconductor element making up the inverter, the relays installed between the main battery and the inverter 12, fuses, etc. The current would be exceeded, making charging virtually impossible. Furthermore, if the main battery is a battery such as a Zn-Br battery or a Ni-Cd battery that requires complete discharge to maintain its characteristics, the main battery voltage decreases after complete discharge, making charging impossible. Therefore, even if the voltage of the main battery is set to a certain degree higher than the peak value of the AC power supply voltage, it is difficult to avoid the above-mentioned problems.

The present invention was made with the aim of solving these problems, and provides an electric vehicle that can be charged even when the voltage of the main battery is low, such as after a complete discharge. The purpose is to provide a charging device for

0010

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a charging opening/closing means provided between an AC power terminal and the motor to open/close the connection between the motor and the inverter. , a main switching means for opening and closing the connection between the main battery and the inverter, and a resistor provided between the inverter and the main battery or between the inverter and the AC power supply terminal;
The control device includes a sub-switching means for opening and closing the connection between the inverter and the main battery or the inverter and the AC power supply terminal via a resistor, and a voltage detector that detects the value of the DC voltage output from the main battery, At least when the connection between the motor and the inverter is open, the main opening/closing means and the auxiliary opening/closing means are controlled in accordance with the charging command supplied from the charging switch, etc., and the inverter and the main battery or the inverter and the AC power terminal are connected with a resistor. means for connecting via;
The output voltage value of the main battery detected by the voltage detector is compared with the reference value corresponding to the peak voltage of the AC power supply connected to the AC power supply terminal, and the output voltage value of the main battery reaches the reference value. means for maintaining the opening/closing state of the auxiliary opening/closing means until the output voltage value of the main battery reaches a reference value; A means for rectifying an AC voltage of a predetermined value supplied from an AC power source via an AC power supply terminal by controlling a switching element of an inverter in response to a short-circuit between both ends of a resistor; , means for converting the DC voltage of the main battery into an AC current of a predetermined number of phases to be supplied to the motor in accordance with a motor drive command from an accelerator, etc., and by controlling the inverter in accordance with the motor drive command. By driving the motor and using the inverter in regeneration mode according to charging commands, the output of the AC power source is rectified to charge the main battery, and when the voltage of the main battery is low, the main battery is charged via the resistor. It is characterized by

[0011]

[Operation] In the present invention, when the main battery is charged using the inverter in regeneration mode and the voltage of the battery is low, the charging current is limited by the resistor.

That is, the charging operation according to the present invention is as follows. First, when a charging command is given to the control device from a charging switch or the like while at least the connection between the motor and the inverter is open, the control device controls the main opening/closing means and the sub opening/closing means. Through this control, a resistor is inserted between the inverter and the main battery or between the inverter and the AC power terminal.

[0013] At this time, the control device compares and determines the detection result of the voltage detector with a reference value. That is,
It is determined whether the output voltage value of the main battery detected by the voltage detector has reached a predetermined reference value. This reference value is set to a value corresponding to the peak voltage that appears at the main battery side terminal of the inverter as a result of connecting the AC power supply to the AC power supply terminal. Therefore, this comparison operation in the control device corresponds to a comparison to determine whether the voltage of the main battery has reached a state where there is no difference from the AC voltage peak value.

[0014] Such comparisons are repeated, and if it is determined that the output voltage of the main battery has reached the reference value, the control device closes the connection between the main battery and the inverter. That is, a connection state is established without using a resistor, and charging is performed in regeneration mode.

As described above, in the present invention, when the inverter is used in the regeneration mode to charge the main battery in response to a charging command, if the peak of the voltage output from the inverter is higher than the voltage of the main battery, The main battery is charged while the current is limited by the resistor. Therefore, it is possible to avoid exceeding the allowable current of the main switching means and the like. Furthermore, even if the main battery is completely discharged, it can be charged.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. Note that the same configurations as those of the conventional example shown in FIG. 5 are given the same reference numerals, and explanations thereof will be omitted.

FIG. 1 shows the configuration of an electric vehicle charging device according to a first embodiment of the present invention. The device shown in this figure includes a main battery 10, a three-phase inverter 12, a motor 14, and a control device 16, similar to the conventional example shown in FIG. That is, the DC voltage output from the main battery 10 is controlled by the inverter 12 of the control device 16.
The current is converted into a three-phase alternating current and supplied to the motor 14. The motor 14 is driven to rotate by this supply, and its torque becomes a value determined according to the contents of the vector control of the control device 16.

Further, this embodiment has a function of charging the main battery 10 by using the inverter 12 in the regeneration mode, similar to the conventional example shown in FIG. That is, the motor 14 is connected between the inverter 12 and the motor 14 during charging.
A switch 20 is provided to disconnect the inverter 12, and an AC power supply terminal 18 is provided between the switch 20 and the inverter 12 via a reactor 22. On the other hand, a main relay 24 is provided between the main battery 10 and the inverter 12, and is turned on when the motor 14 is driven, and is blown out when the current flowing through the main relay 24 exceeds an allowable current value. A fuse 26 with a predetermined current capacity is provided. Also, when the motor 14 is driven, the main battery 1
A capacitor 2 that stabilizes the voltage output from 0 and smoothes the voltage output from the inverter 12 during charging.
8 is connected in parallel to the main battery 10 side terminal of the inverter 12. In addition, a resistor 3 is connected in parallel with the main relay 24 to limit the current when charging the capacitor 28.
0 is connected, and a sub-relay 32 is provided to open and close the flow path related to the resistor 30. Main battery 10
A voltage detector 34 is connected in parallel to the two, and the output of the voltage detector 34 is given to the control device 16.

First, the operation of the motor 14 in this embodiment when it is driven will be explained as follows.

When starting the motor 14, first, a motor drive command is given to the control device 16 from an accelerator or the like. The control device 16 operates the sub-relay 32 by issuing a relay drive signal, and connects the resistor 30 to the main battery 10.
is interposed between the capacitor 28 and the inverter 12. That is, the relay 32 is turned on. It is assumed that at this time, the main relay 24 is off, and the main battery 10, capacitor 28, and inverter 12 are not directly connected.

Therefore, in this state, the current flowing from the main battery 10 to the inverter 12 and capacitor 28 is limited by the resistor 30. That is, if the main battery 10 is connected to the inverter 12 without the resistor 30 intervening, the current flowing into the capacitor 28 will be excessive and the fuse 26 will blow. In order to avoid this, in this embodiment, the sub-relay 32 is turned on only at the time of startup, and the resistor 30 is interposed between the main battery 10 and the capacitor 28 and the like.

When the charging of the capacitor 28 progresses and it is recognized that there is almost no difference between the voltage across the main battery 10 and the voltage across the capacitor 28, that is, when the resistor 30
When a time period corresponding to a time constant determined by the resistance value of the capacitor 28 and the capacitance value of the capacitor 28 has elapsed, the control device 16 turns on the main relay 24. Then, both ends of the resistor 30 and the sub-relay 32 are short-circuited, and the main battery 10, the capacitor 28, and the inverter 12 are short-circuited without using the resistor 30. The control device 16 controls switching elements such as transistors constituting the inverter 12 using element drive pulses, converts the output voltage of the main battery 10 into a three-phase AC voltage using a conventionally known method, and supplies the voltage to the motor 14. In addition,
It is assumed that the switch 20 is turned on at this time.

Therefore, in this embodiment, the motor 14
The current is limited by the resistor 30 only when the capacitor 28 is started, and the resistor 30 is removed when the transient current accompanying the charging of the capacitor 28 decreases, thereby realizing drive without heat loss.

[0024] Such an operation, particularly an operation when starting the motor 14, has been conventionally used. The feature of this embodiment is that the resistor 30 used to limit the current when starting the motor 14 is used to limit the current when the inverter 12 is used in regeneration mode to charge the main battery 10 with the output of the AC power source. The point is that it can be used as a resistor.

Next, the operation when charging the main battery 10 using the inverter 12 will be explained.

FIG. 2 shows the flow of operations in this embodiment, particularly the flow of operations when charging the main battery 10.

First, for example, 20
When an AC power supply that outputs 0V AC voltage is connected (1
00), the control device 16 transitions to a charging command waiting state (
102). That is, the control device 16 waits for a charging command from a charging switch or the like and then executes the charging operation according to the feature of this embodiment.

When a charging command is given, the control device 16 issues a relay drive signal to turn on the sub-relay 32 (1
04). It is assumed that the main relay 24 is off and the switch 20 is off at this time. Therefore, in this state, the AC power source is connected to the inverter 12 via the AC power terminal 18 and the reactor 22, and the inverter 12 is connected to the main battery via the resistor 30.
It becomes connected to 0.

Next, the control device 16 controls the voltage detector 3.
The detection results of No. 4 are imported (106). That is, the voltage detector 34 provided in parallel with the main battery 10 detects the voltage across the main battery 10 and provides this to the control device 16 as a voltage signal. Control device 16 performs a predetermined comparison operation 108 in response to this voltage signal.

In step 108, the voltage detector 3
The voltage value VB of the main battery 10 indicated by the voltage signal supplied from the main battery 4 is compared with a predetermined voltage value V. This voltage value V is set according to the output voltage value of the AC power supply connected to the AC power supply terminal 18. For example, it is set to a value slightly lower than the peak value of the AC voltage output from this AC power supply. Therefore, the comparison in step 108 determines whether the voltage of the main battery 10 has almost reached the peak voltage of the AC power supply.

If it is determined in step 108 that VB≦V, it is considered that the voltage VB of the main battery 10 is low. For example, it is considered that the main battery 10 has performed a complete discharge operation immediately before, and the output voltage is in a reduced state. Therefore, in this embodiment, if it is determined in determination 108 that VB≦V, the process returns to step 106 and the voltage detection operation is repeated. In other words, the next step 11 is performed only when the voltage VB of the main battery 10 exceeds the predetermined voltage value V.
Transition to 0.

During the period in which these steps 106 and 108 are repeated, the main battery 10 is charged with a current whose value is limited by the resistor 30. As previously explained regarding the conventional example shown in FIG. 5, when the peak of the output voltage of the AC voltage connected to the AC power supply terminal 18 exceeds the voltage of the main battery 10,
This makes it impossible to control the charging current of the main battery 10. In this embodiment, even in this situation, i.e., when steps 106 and 108 are repeated, the resistor 30 is connected to the inverter 12.
Since the main battery 10 is interposed between the main battery 10 and the main battery 10, it is possible to charge the main battery 10 without causing the fuse 26 to melt, even though the current cannot be controlled by the control device 16.

As described above, when the main battery 10 is repeatedly charged with the current whose value is limited by the resistor 30,
At some point, the voltage VB of the main battery 10 reaches step 1
This satisfies the comparison conditions in 08. That is,
VB>V. Therefore, current limitation by the resistor 30 is not necessary. In response, control device 16 generates a relay drive signal and turns on main relay 24. Then, both ends of the resistor 30 are short-circuited, and therefore, charging operation of the main battery 10 without going through the resistor 30 is started. In this state, the control device 16 applies element drive pulses to the switching elements of the inverter 12 and executes a charging operation in the regeneration mode similar to the conventional example described above (11
2).

Therefore, in this embodiment, even if the peak value of the output voltage of the AC power supply connected to the AC power supply terminal 18 exceeds the voltage of the main battery 10, the main battery 10 can be charged. It is possible. That is, it is possible to perform charging while limiting the current using the resistor 30. Further, the resistor 30 related to this current limit is connected to the motor 1
Because it is shared with the resistor used to start 4,
This means that changes in the design of the device can be made on a small scale.

FIG. 3 shows the configuration of an electric vehicle charging device according to a second embodiment of the present invention.

In the device shown in this figure, a resistor 30 and a sub-relay 32 are not provided in parallel with the main relay 24, but a resistor 30 is provided in series with the reactor 22, and a sub-relay 32 is provided in parallel with the resistor 30. It is being Further, the number of contacts of these resistors 30 and sub-relays 32 is set to three depending on the number of phases.

The operation of the motor 14 in this embodiment when it is driven is similar to that of the first embodiment described above. Note that although a resistor for limiting the transient current of the capacitor 28 and a relay for inserting this resistor are not shown in the second embodiment, they may be provided in the same manner as in the first embodiment. In addition, if not provided, fuse 2
It is necessary to design the main battery 10 so that the main battery 10 wiring does not experience an overcurrent.

FIG. 4 shows the operation of charging the main battery 10 in this embodiment. In this embodiment, first, as in the first embodiment, the AC power supply terminal 1
After the AC power supply is connected to the controller 8 (200), the controller 16
transitions to a charging wait state (202). When a charging command is given from a charging switch or the like, the control device 16 generates a relay drive signal to turn on the main relay 24 (2
04). Note that at this time, it is assumed that the switch 20 is off and the sub-relay 32 is also off. Therefore,
At this time, the inverter 12 is connected to the resistor 30 and the reactor 2.
2 to the AC power supply terminal 18, and is connected to the main battery 10 via the main relay 24.

Subsequently, the voltage signal from the voltage detector 34 is taken in by the control device 16 (206). Subsequently, step 208 is executed, and the voltage V of the main battery 10 is
B is compared with a predetermined value V. The operations in step 206 and step 208 are similar to those in the first embodiment shown in FIG.

Thereafter, when the comparison condition in step 208 is satisfied, the process moves to step 210. In step 210, the control device 16 issues a relay drive signal to turn on the sub-relay 32. Then, both ends of the resistor 30 are short-circuited, and the AC power supply terminal 1
8 is connected to the inverter 12 via the reactor 22. As a result, the first
As in the embodiment, the main battery 10 can be charged using the inverter 12 in the regeneration mode (212).

Therefore, in this embodiment as well, the above-mentioned first
Effects similar to those of the embodiment can be obtained. Furthermore, in this case, the resistance value of the resistor 30 can be selected without considering the restriction of the current flowing into the capacitor 28 when the motor 14 is started, thereby increasing the degree of freedom in designing the device.

[0042]

[Effects of the Invention] As explained above, according to the present invention,
When attempting to charge the main battery by using the inverter in regeneration mode, the main battery can be charged even if the peak value of the output voltage of the AC power supply is higher than the voltage of the main battery. In other words, by interposing a resistor between the main battery and the inverter or between the inverter and the AC power supply input terminal, it is possible to limit the current to a value that does not exceed the allowable current of the inverter components. Charging can be performed even when the battery is fully discharged.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an electric vehicle charging device according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing the operation when charging the main battery in the first embodiment.

FIG. 3 is a diagram showing the configuration of an electric vehicle charging device according to a second embodiment of the present invention.

FIG. 4 is a flowchart showing the operation when charging the main battery in the second embodiment.

FIG. 5 is a diagram showing the configuration of an electric vehicle charging device according to a conventional example.

[Explanation of symbols]

10 Main battery 12 Inverter 14 Motor 16 Control device 18 AC power supply terminal 20 Switch 24 Main relay 30 Resistance 32 Sub relay

Claims (1)

[Claims] Claim 1: A main battery that outputs a predetermined DC voltage;
A motor that is driven by alternating current of a predetermined number of phases and generates drive torque for an electric vehicle, and a plurality of switching elements and diodes connected in parallel are connected in series for each phase, and these series connections are connected to the main battery. The inverter is connected in parallel to the AC power supply terminal and the connection point for series connection is connected to the motor and the AC power terminal, and the charging inverter is connected between the AC power terminal and the motor to open and close the connection between the motor and the inverter. A switching means, a main switching means for opening and closing the connection between the main battery and the inverter, a resistor provided between the inverter and the main battery or between the inverter and the AC power supply terminal, and an inverter and the main battery or the inverter and the AC power supply terminal. A sub-switching means that opens and closes connections via terminal resistances, a voltage detector that detects the value of the DC voltage output from the main battery, a switching means for turning on and off switching elements of the inverter, a charging switching means, a main switching means and a sub-switching means. a control device that controls opening and closing of the opening/closing means, and the control device controls the main opening/closing means and the auxiliary opening/closing means in response to a charging command supplied from a charging switch or the like while at least the connection between the motor and the inverter is open. means for controlling the inverter and the main battery or the inverter and the AC power supply terminal via a resistor, a reference value corresponding to the peak voltage of the AC power supply connected to the AC power supply terminal, and detection by a voltage detector. means for maintaining the open/closed state of the auxiliary opening/closing means until the output voltage value of the main battery reaches the reference value, and the output voltage value of the main battery reaches the reference value. In this case, by controlling the main switching means or the sub-switching means to short-circuit both ends of the resistor, and by controlling the switching element of the inverter according to the charging command and the short-circuiting of both ends of the resistor, By controlling the switching element of the inverter and the means for rectifying the AC voltage of a predetermined value supplied from the power supply, the DC voltage of the main battery can be supplied to the motor in accordance with the motor drive command from the accelerator or the like. means for converting the AC current into an AC current, the motor is driven by controlling the inverter according to the motor drive command, and the output of the AC power source is rectified by using the inverter in a regeneration mode according to the charging command. 1. A charging device for an electric vehicle, characterized in that the main battery is charged through a resistor when the voltage of the main battery is low.