JPH10304501A - Electric vehicle control device - Google Patents

Abstract

(57) [Problem] To reliably determine the end of precharging of a capacitor provided in an inverter of an electric vehicle. An after ON precharge contactor at step S2, the predetermined time T ₁ is elapsed in step S3 is precharged capacitor is estimated that almost finished, based on the precharge end current If in step S8 The value I _{REF is} compared to confirm that If ≦ I _REF . Further, in step S9, the precharge start voltage Vi is set to the reference value V.
If exceeds the _REF, or equal to or less than the pre-charge start voltage Vi is the reference value V _REF in step S9, and the pre-charge start voltage Vi and deviation [Delta] V = Vf-Vi reference precharge end voltage Vf in step S10 Value ΔV
If it is equal to or greater than _REF, it is determined that the precharge has been completed. Then, in step S11, the main contactor 1
3 and the precharge contactor 14 is turned off in step S12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an electric vehicle having an inverter for driving a traveling motor by converting DC power of a main battery into AC power.

[0002]

2. Description of the Related Art A large-capacity electrolytic capacitor is provided between terminals on the input side of an inverter of an electric vehicle in order to smooth voltage fluctuations and stabilize the operation of the inverter. When the electric vehicle is driven, the contactor is closed and the capacitor is charged by operating the main switch. However, if the capacitor is directly charged with the main battery, a large current flows and the contactor of the contactor may be damaged. Therefore, first, the precharge contactor is closed, the capacitor is precharged while limiting the current with a resistor or the like, and the main contactor is closed after the precharge is completed, thereby preventing damage to the contacts.

The following has been proposed as a method for determining the end of the precharge. A method for determining that the precharge has been completed when a predetermined time has elapsed since the start of the precharge (Japanese Patent Laid-Open No.
A method of determining that the precharge has ended when the capacitor voltage becomes equal to or higher than the reference value after the start of the precharge (see US Pat. No. 5,369,540). Method to judge that precharging has ended when the amount of rise in capacitor voltage exceeds a reference value

[0004]

However, in the above method, even when the precharge contactor fails and cannot be precharged, the main contactor closes after a predetermined time has elapsed, so that a large current can flow through the main contactor. There is. In addition, even when the electric charge of the capacitor is discharged to the electric load during the precharge, the above problem occurs because the precharge is not completed even after the predetermined time has elapsed.

In the above method, when the voltage of the main battery is lowered, the capacitor voltage may not rise above the reference value. In this case, it is impossible to determine the end of the precharge. If the reference value is set low to avoid this, there is a possibility that the main contactor is closed and the large current flows when the precharge of the capacitor is insufficient.

In the above method, the capacitor voltage does not completely decrease when the main switch is closed immediately after the main switch is opened. Therefore, the amount of increase in the capacitor voltage does not exceed the reference value, and the termination of the precharge is terminated. There is a possibility that judgment cannot be made.

The present invention has been made in view of the above circumstances, and has as its object to reliably determine the end of precharging of a capacitor provided in an inverter of an electric vehicle.

[0008]

According to the first aspect of the present invention, it is determined that the precharge has ended when the precharge current after a predetermined time from the start of the precharge is equal to or less than the reference value. In the event that the charge of the capacitor is discharged to the electric load, the precharge current does not become lower than the reference value, so that it is possible to avoid erroneous determination of the end of precharge. In addition, even when the voltage of the main battery decreases and the precharge end voltage does not increase to the reference value or more, the precharge end determination can be made if the precharge current becomes equal to or less than the reference value.

The predetermined time (Ti) is a time from the start of the precharge to the time when it is estimated that the charging of the capacitor is almost completed, and is a value that can be determined by the time constant of the precharge circuit. The reference value (I _REF ) is
If the precharge current is equal to or less than the reference value, it is a value that can be determined that precharge has been completed, and is a design value that can be arbitrarily set within the range.

According to the second aspect of the invention, the precharge is stopped when the integrated value of the precharge current becomes equal to or more than the reference value before a predetermined time has elapsed from the start of the precharge. In the event of abnormal discharge of electric power to the electric load, the integrated value becomes equal to or higher than the reference value and precharging is stopped, so that it is possible to prevent wasteful precharge current from being consumed.

The reference value (ΔI _REF ) is a value which can be determined as a state in which the electric charge is discharged from the capacitor to the electric load if the integrated value of the precharge current is equal to or larger than the reference value. This is a design value that can be set arbitrarily.

According to the third aspect of the invention, when the capacitor voltage at the start of the precharge exceeds the reference value, the main switch 8 is turned on immediately after the main switch 8 is turned off. , It can be determined that the precharge has been completed if a predetermined time has elapsed from the start of the precharge. When the capacitor voltage at the start of precharge is lower than the reference value, a sufficient time has elapsed since the main switch 8 was turned off, and the capacitor has been sufficiently discharged. When the difference between the voltage and the capacitor voltage after a predetermined time from the start of the precharge is equal to or larger than the reference value, it can be determined that the precharge has been completed. In the case of an abnormality in which the electric charge of the capacitor is discharged to the electric load during the precharge, the deviation does not exceed the reference value, so that erroneous determination of the end of the precharge can be avoided.

The predetermined time (Ti) is a time from the start of precharge to the time when it is estimated that the charging of the capacitor is almost completed, and is a value that can be determined by the time constant of the precharge circuit. The former reference value (V _REF ) is a value that can be estimated to end precharging after the lapse of the predetermined time if the capacitor voltage at the start of precharging exceeds the reference value. Is a design value that can be set arbitrarily. The latter reference value (ΔV _REF ) is a value that can be determined to be the end of the precharge if the deviation of the capacitor voltage before and after the precharge is equal to or more than the reference value, and can be arbitrarily set within the range. This is a design value.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIGS. 1 to 4 show an embodiment of the present invention. FIG. 1 is a diagram showing an entire configuration of an electric vehicle, FIG. 2 is a block diagram of a control system, FIG. FIG. 4 is a time chart for explaining the operation.

As shown in FIGS. 1 and 2, a four-wheel electric vehicle V has a pair of left and right front wheels Wf as drive wheels to which the torque of a traveling motor 1 composed of a three-phase AC motor is transmitted via a differential 2. , Wf and a pair of left and right rear wheels Wr, Wr as driven wheels. For example, a main battery 3 of 288 volts mounted on the rear of the electric vehicle V
Is connected to the traveling motor 1 via a contactor 4, a joint box 5, and an inverter 6 constituting a power drive unit. For example, an electronic control unit 10 connected to a 12-volt sub-battery 7 via a main switch 8 and a fuse 9 is connected to an inverter 6 for controlling the driving torque and the regenerative torque of the traveling motor 1. The joint box 5 has a battery charger 11 for charging the main battery 3 with electric power from an external power supply.
Are connected, and a DC / DC converter 12 is connected to charge the sub-battery 7 with the power of the main battery 3.

The contactor 4 has a main contactor 13 and a precharge contactor 14 connected in parallel, and a precharge resistor 15 is connected to the precharge contactor 14 in series. The DC / DC converter 12 is connected to the main battery 3 via a charge control contactor 16. These main contactors 1
3. The opening and closing of the precharge contactor 14 and the charge control contactor 16 are controlled by the electronic control unit 10.

A current sensor S ₁ provided in a DC section connecting the main battery 3 and the inverter 6 detects a current I _PDU flowing through the main contactor 13 when the electric vehicle V runs.
And a current I _{P / C} flowing through the precharge contactor 14 when the smoothing capacitor 17 composed of an electrolytic capacitor connected in parallel between the high potential input terminal and the low potential input terminal of the inverter 6 is precharged. I do. The current I _{P / C} flowing through the precharge contactor 14 having the precharge resistor 15
Is smaller than the current I _PDU flowing through the main contactor 13, the coil is wound once around the lead connected to the main contactor 13, and the coil is wound a plurality of times (five times in the embodiment) around the lead connected to the precharge contactor 14. Current flowing through the precharge contactor 1
4 can be detected with a small current and the common current the accuracy sensor S ₁ through the. This current sensor S ₁ is connected to the electronic control unit 10.

The voltage sensor S ₂ connected to the electronic control unit 10 detects the voltage V _PDU of the DC section connecting the main battery 3 and the inverter 6 when the electric vehicle V runs, and when the capacitor 17 is precharged. The voltage V _{P / C} of the capacitor 17 is detected. Furthermore the motor rotation speed Nm detected by the motor rotational speed sensor S _3, the accelerator opening theta _AP detected by the accelerator opening sensor S _4, the shift range R detected by the shift range sensor S ₅ is the electronic control unit 10 Is entered.

The inverter 6 has a plurality of switching elements. By inputting a switching signal from the electronic control unit 10 to each switching element, the DC power of the main battery 3 is converted into three-phase AC power when the traveling motor 1 is driven. The three-phase AC power generated by the traveling motor 1 is converted to DC power when the traveling motor 1 is driven (during regeneration), and supplied to the main battery 3.
To supply.

In a region on the low rotation speed side of the traveling motor 1, the inverter 6 is subjected to PWM (pulse width modulation) control,
In the region on the high rotational speed side after the duty ratio of the M control reaches 100%, so-called field weakening control is performed. The field-weakening control is a method in which a primary current supplied to the traveling motor 1 has a field current component so that a field in a direction opposite to a field generated by a permanent magnet of the traveling motor 1 is generated. To extend the rotation speed of the traveling motor 1 to a higher rotation speed side.

Next, the operation of the electric vehicle V during traveling will be described.

The electronic control unit 10 includes a motor rotation speed Nm detected by the motor rotational speed sensor S _3, the accelerator opening theta _AP detected by the accelerator opening sensor S _4, the shift range detected by the shift range sensor S ₅ Based on R,
A torque command value Q _TRQ that the driver intends to generate on the traveling motor 1 is calculated based on a preset torque map. And to be supplied to the motor rotation speed Nm detected by the torque command value Q _TRQ and the motor rotational speed sensor S ₃ in to the traveling motor 1 multiplication, or to calculate a target power to be taken out from the traveling motor 1 by the regenerative. The target power may be a positive value or a negative value. The positive target power corresponds to the case where the traveling motor 1 generates the driving torque, and the negative target power corresponds to the case where the traveling motor 1 generates the regenerative torque. Corresponding to

On the other hand, the electronic control unit 10 outputs a current I _PDU of the DC section of the inverter 6 detected by the current sensor S ₁ ,
By multiplying the voltage V _{PD U} DC of the inverter 6 that is detected by the voltage sensor S _2, calculates the actual power input to the inverter 6. Similarly to the target power, the real power also has a positive value and a negative value. The positive real power corresponds to the case where the traveling motor 1 generates a driving torque, and the negative real power corresponds to the case where the traveling motor 1 generates a driving torque. Corresponds to the case where a regenerative torque is generated. Then, the target electric power is compared with the actual electric power, and the traveling motor 1 is feedback-controlled so that the deviation converges to zero.

Next, the operation when the capacitor 17 provided in the inverter 6 is precharged will be described with reference to the flowchart of FIG.

[0026] First, the capacitor 17 when the electric vehicle V is in a state before traveling there remains a slight charge, the voltage V _P of the capacitor 17 in the precharge start detected by the voltage sensor S ₂ in step S1 _{/ C} (that is,
The precharge start voltage Vi) is read. Subsequently, when the main switch 8 is turned on to run the electric vehicle V, the precharge contactor 14 is turned on in step S2.
Then, charging of the capacitor 17 connected to the main battery 3 via the precharge resistor 15 and the precharge contactor 14 is started. At this time, the inrush current at the moment when the precharge contactor 14 is turned on is reduced by the precharge resistor 15, so that the contact of the precharge contactor 14 can be prevented from being damaged.

In step S3, a predetermined time T₁(For example, 2
(Seconds) until the current sensor S
₁Precharge current I detected at_{P / C}And the current product
A calculated value ΔI is calculated, and in step S5, the current integrated value ΔI is calculated.
With reference value ΣI_REFCompare with Predetermined in step S3
Time T₁Before the time elapses, the current integrated value ΣI becomes equal to the reference value ΣI
_REFIn this case, the electric charge from the capacitor 17
It is determined that an abnormality such as escape has occurred, and step S1
2 to turn off the precharge contactor 14 and
Interrupt the page. This results in wasted precharge current
I_{P / C}Can be prevented from being consumed.

[0028] When the predetermined time T ₁ is elapsed in step S3, the process proceeds to step S6, S7 estimated that precharge is almost completed when viewed in time, in the pre-charge end detected by the voltage sensor S ₂ The capacitor voltage V _{P / C} (that is, precharge end voltage Vf) is read, and the precharge current I _{P / C} at the end of precharge detected by the current sensor S ₁ (that is, precharge end current If) is read.

In the following step S8, the precharge end current If is compared with a reference value I _REF, and the precharge end current I
If f exceeds the reference value I _REF, it determines that the precharge is not yet completely finished, to re-execute the pre-charge of the predetermined time T ₁ and returns to step S2. Reference value precharge end current If in step S8 I _{RE F}
If it becomes less than or equal to, the precharge start voltage V
i is compared with a reference value V _REF and a precharge start voltage Vi
Is greater than the reference value V _REF , step S1
It is determined that the precharge has been completed without waiting for the determination of 0, the main contactor 13 is turned on in step S11, and the precharge contactor 1 is determined in step S12.
4 is turned OFF.

[0030] This is because, the state precharge start voltage Vi at step S9 that exceeds the reference value V _REF, the capacitor 17 in a case such as ON immediately after OFF the main switch 8 is charged already sufficiently because of the, then it is because it reliably determine the completion of the precharge if the predetermined time T ₁ is elapsed. Thus, it was on condition that precharge start voltage Vi exceeds the reference value V _REF, since determining the completion of the precharge after the elapse of the predetermined time T _1, a large current when the ON the main contactor 13 Flows and the main contactor 13 is not damaged. Note that the reference value V _REF is set to 200 volts with respect to the voltage of the main battery 3 of 288 volts in the embodiment.

If the precharge start voltage Vi is equal to or lower than the reference value _VREF in step S9, the precharge start voltage Vi and the precharge end voltage Vf are set in step S10.
The deviation [Delta] V = Vf-Vi is compared with the reference value [Delta] V _REF, the process proceeds to step S11 it is determined that the deviation [Delta] V is the reference value [Delta] V _REF higher value, if the pre-charge has been completely finished,
If the difference ΔV is smaller than the reference value ΔV _REF , it is determined that the precharge has not been completely completed, and step S2
Try again precharging of the predetermined time T ₁ and returns to. Note that the reference value ΔV _REF is set to 25 volts with respect to the voltage of the main battery 3 of 288 volts in the embodiment.

In the embodiment, the end of the precharge is determined by a combination of the determinations of steps S3, S8 to S10 in the flowchart of FIG. 3, but also by a combination of the determinations of steps S3, S8, steps S3, S9, S
The end of precharge can also be accurately determined by a combination of the ten determinations.

According to the combination of the determination in step S3, S8, after being estimated to have been completed precharging almost elapsed from the precharge start the predetermined time T ₁ is, the precharge end current If the reference value I _REF It is determined that the precharge is completely completed when the following conditions are satisfied. Therefore, in the event of an abnormality in which the electric charge of the capacitor 17 is discharged to the electric load during the precharge, the precharge end current If does not become lower than the reference value _IREF , so that it is possible to avoid erroneous determination of the end of the precharge. Is resolved. Further, even when the voltage of the main battery 3 decreases and the precharge end voltage Vf does not increase to the reference value or more, it is possible to determine the end of the precharge if the precharge end current If becomes equal to or less than the reference value _IREF. The above-mentioned problem is solved.

According to the combination of the determinations in steps S3, S9, and S10, the precharge start voltage Vi is changed to the reference value V _REF after it is estimated that the precharge is almost completed after a predetermined time has elapsed from the start of the precharge. less and, and determines that the precharge start voltage Vi and the precharge if the deviation [Delta] V of the pre-charge end voltage Vf is the reference value [Delta] V _REF or completely finished. Therefore, when the charge of the capacitor 17 is discharged to the electric load during the precharge, the deviation ΔV does not become equal to or less than the reference value ΔV _REF , so that the erroneous determination of the end of the precharge can be avoided, and the above-mentioned problem is solved. Is done. When the pre-charge start voltage Vi is high because of closed again immediately after opening the main switch 8 In addition, since a verdict of precharge end without comparing the deviation [Delta] V to the reference value [Delta] V _{RE F,} problems in the Is resolved.

Next, the above operation will be further described with reference to the time chart of FIG.

Time T ₀ after turning on the main switch 8
Is elapsed and the electronic control unit 10 becomes operable,
The precharge contactor 14 is turned on and the predetermined time T
_{After 1} elapses, the main contactor 13 turns on. Thereafter, when the time T ₂ elapses, the precharge contactor 14
There was OFF, it is allowed to launch a further time T ₃ has elapsed high load (inverter 6).

At the same time as the precharge contactor 14 is turned on, the precharge current I _{P / C} sharply rises, and as the capacitor 17 is charged, the precharge current I _{P / C} rises.
_{P / C} decreases slowly. At this time, in the case of an abnormality in which the charge is escaping from the capacitor 17, the precharge end current If becomes higher than in the normal state as indicated by the broken line, and as a result If> _IREF , the abnormality is determined. At the same time as the precharge contactor 14 is turned on, the capacitor voltage VP _{/ C} gradually increases from the precharge start voltage Vi. However, when the charge is escaping from the capacitor 17, the precharge end voltage Vf is normal as shown by a broken line. As a result, ΔV <ΔV _REF , and an abnormality is determined.

Although the embodiments of the present invention have been described in detail, various design changes can be made in the present invention without departing from the gist thereof.

[0039]

As described above, according to the first aspect of the present invention, there is provided a current detection means for detecting a precharge current, and the control means comprises a precharge current after a predetermined time from the start of the precharge. Is less than or equal to the reference value, it is possible not only to avoid the erroneous determination of the end of the precharge at the time of abnormality where the electric charge of the capacitor is discharged to the electric load during the precharge, Even when the voltage of the main battery decreases and the precharge end voltage does not increase to the reference value or more, it is possible to accurately determine the end of the precharge.

According to the second aspect of the present invention,
The control means stops the precharge when the integrated value of the precharge current becomes equal to or more than the reference value before the predetermined time elapses. Therefore, when the charge of the capacitor is discharged to the electric load during the precharge, useless precharge is performed. Current consumption can be prevented.

According to the third aspect of the present invention,
It is provided with voltage detecting means for detecting a capacitor voltage,
When the capacitor voltage at the start of the precharge exceeds the reference value, the control means determines that the precharge has been completed a predetermined time after the start of the precharge. In this case, when the capacitor is in a sufficiently charged state, the end of the precharge can be accurately determined. In addition, the end of precharge is determined after the elapse of the predetermined time from the start of the precharge only when the capacitor voltage at the start of the precharge is high, so that the capacitor is sufficiently charged after the elapse of the predetermined time. Therefore, there is no possibility that a large current flows when the main contactor is closed and the main contactor is damaged. Further, when the capacitor voltage at the start of precharge is equal to or lower than the reference value, the precharge is terminated when the difference between the capacitor voltage at the start of precharge and the capacitor voltage after a predetermined time from the start of precharge is equal to or higher than the reference value. Therefore, it is possible to avoid the erroneous determination of the end of the precharge at the time of abnormality in which the electric charge of the capacitor is discharged to the electric load during the precharge.

[Brief description of the drawings]

FIG. 1 is a diagram showing an entire configuration of an electric vehicle.

FIG. 2 is a block diagram of a control system.

FIG. 3 is a flowchart illustrating an operation.

FIG. 4 is a time chart for explaining the operation;

[Explanation of symbols]

REFERENCE SIGNS LIST 1 traveling motor 3 main battery 6 inverter 10 electronic control unit (control means) 13 main contactor 14 precharge contactor 17 capacitor S ₁ current sensor (current detection means) S ₂ voltage sensor (voltage detection means) I _{P / C} precharge current If Precharge current after predetermined time from start of precharge I _REF Reference value of precharge current VP _{/ C} capacitor voltage Vf Capacitor voltage after predetermined time from start of precharge Vi Capacitor voltage at start of precharge V _REF capacitor voltage deviation [Delta] V _REF deviation reference value T ₁ predetermined time reference value [Delta] V capacitor voltage reference value .SIGMA.I integrated value .SIGMA.I _REF integrated value of precharge current

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H02P 5/41 302 H02P 5/41 302D (72) Inventor Shishinobu 1-4-1 Chuo, Wako-shi, Saitama Inside the Technical Research Institute (72) Inventor Masaki Amami 1-4-1 Chuo, Wako-shi, Saitama Prefecture Honda Research Institute (72) Inventor Koji Ito 4-3-1 Shinjuku, Shinjuku-ku, Tokyo Keihin Corporation Inside

Claims (3)

[Claims] An inverter (6) for converting a DC power of a main battery (3) into an AC power to drive a traveling motor (1), and a main provided between the main battery (3) and the inverter (6). A contactor (13); a precharge contactor (14) provided between the main battery (3) and the inverter (6); a smoothing capacitor (17) connected in parallel with the inverter (6); A control unit (10) for closing the contactor (14) to precharge the capacitor (17) and closing the main contactor (13) when it is determined that the precharge is completed. it includes a pre-charge current current detecting means for detecting _{(I P / C) (S} 1), said control means (10) is predetermined from the precharge start During (T ₁₎ pre-charge current (If) control apparatus for an electric vehicle, characterized in that to determine that the pre-charge is completed when the reference value (I _REF) following after. 2. The control means (10) determines that the integrated value (ΣI) of the precharge current (IP _{/ C} ) becomes equal to or more than a reference value (ΣI _REF ) before the predetermined time (T ₁ ) elapses. The control device for an electric vehicle according to claim 1, wherein the precharge is stopped. 3. The DC power of the main battery (3) is converted to AC.
Inverter that converts electric power to drive the traveling motor (1)
(6), provided between the main battery (3) and the inverter (6).
Provided between the main contactor (13) and the main battery (3) and the inverter (6).
Pre-charged contactor (14) and a smoothing capacitor connected in parallel with the inverter (6)
(17) Close the precharge contactor (14)
(17) is precharged and the precharge is completed
Control to close the main contactor (13) when judged
Means for controlling an electric vehicle, comprising:
And the capacitor voltage (V_{P / C}) For detecting voltage (S)
_Two), And the control means (10) adjusts the capacitor voltage (Vi) at the start of precharge to a reference value.
(V_REF), The precharge starts
The predetermined time (T₁) Later, it is determined that precharge is completed
The capacitor voltage (Vi) at the start of precharging is
Reference value (V_REF) In the following cases,
Capacitor voltage (Vi) and predetermined time from start of precharge
(T₁) And deviation (ΔV) from the capacitor voltage (Vf)
Is the reference value (ΔV _REF) Precharge ends when above
Control device for an electric vehicle,
Place.