JP2012135083A - Control device of electric vehicle - Google Patents

Abstract

In an electric vehicle, the voltage of a high-voltage system is rapidly reduced when a running abnormality such as a collision occurs.
When a collision G is detected by a G sensor, an MGECU 58 determines whether or not a regenerative current is less than a predetermined value. When the regenerative current is less than the predetermined value, the HVECU 54 controls the SMRs 1 and 2 to be off, and at the same time, performs the discharging process of the smoothing capacitor 22. Further, when the HVECU 54 detects a collision, the HVECU 54 operates the electronic control brake system ECB to stop the driving wheel, and quickly sets the regenerative current to less than a predetermined value.
[Selection] Figure 1

Description

  The present invention relates to a control device for an electric vehicle, and more particularly to processing at the time of a collision of an electric vehicle.

  In an electric vehicle, a high voltage system is used to drive a drive motor. Therefore, at the time of a collision of the electric vehicle, it is safe to quickly reduce the high voltage portion to 60 V or less (within 5 seconds after the collision). It is one of the effective solutions for securing. Normally, a battery as a drive power source and a drive system including an inverter and a drive motor are connected by a system main relay (SMR), and when the ignition switch is turned on, the SMR is turned on to connect the battery and the drive system. When the ignition switch is turned off, the SMR is turned off and the battery and the drive system are disconnected. In the event of a collision, it is required to quickly turn off this SMR, but it is necessary to consider the SMR welding due to the SMR cutoff operation during energization. In order to prevent SMR welding, for example, the rotational speed of the drive motor can be monitored, and the SMR can be turned off at the timing when the regenerative power supply to the battery ceases. However, the rotational speed cannot be monitored due to a resolver disconnection at the time of collision. For this reason, it has been proposed to turn off the SMR after a predetermined time has elapsed since the collision was detected.

  In Patent Document 1 below, when the output current from the battery is lower than a predetermined current and the vehicle speed is lower than the predetermined vehicle speed, the main relay (corresponding to SMR) is turned off to prevent welding of the main relay. It is disclosed.

  Further, in Patent Document 2, it is determined whether or not SMR is welded, and when it is determined that SMR is welded, discharging of a smoothing capacitor provided between the battery and the inverter is prohibited. It is disclosed.

JP-A-2005-348583 JP 2008-278560 A

  In a configuration in which the SMR is turned off and the high-voltage capacitor is discharged after a predetermined time has elapsed since collision detection in consideration of SMR welding, at least the predetermined time must be waited and it is difficult to meet the demand for speed. is there.

  It is an object of the present invention to discharge a high-voltage capacitor quickly by turning off the SMR without causing welding of the system main relay (SMR) when a traveling abnormality such as a collision of an electric vehicle occurs. To provide an apparatus.

  The present invention relates to a control apparatus for an electric vehicle that supplies electric power from a battery to a drive motor via a system main relay and a capacitor, the abnormality detection means for detecting a running abnormality of the electric vehicle including a collision, and the abnormality detection A current detecting means for detecting a regenerative current flowing through the system main relay when a running abnormality is detected by the means, and a regenerative current detected by the current detecting means with a threshold value for welding the system main relay as a predetermined value Control means for maintaining the system main relay in an on-control state when the value is greater than or equal to a predetermined value, turning off the system main relay when the value is less than a predetermined value, and controlling the discharging of the capacitor. It is characterized by.

  In one embodiment of the present invention, an operation means is provided that activates a brake that stops the drive wheels of the electric vehicle when a travel abnormality is detected by the abnormality detection means.

  In another embodiment of the present invention, an operation unit is provided that operates a brake that stops the drive wheel of the electric vehicle when the regenerative current detected by the current detection unit is a predetermined value or more.

  In another embodiment of the present invention, the control means simultaneously outputs an off command for controlling the system main relay to be off and a discharge command for controlling the discharge of the capacitor.

  According to the present invention, at the time of running abnormality such as a collision of an electric vehicle, the system main relay (SMR) is not welded, and the SMR is quickly turned off to discharge the high-voltage capacitor to reduce the pressure. Can do.

1 is an overall system configuration diagram of an embodiment. It is a control block diagram of an embodiment. It is a processing flowchart of an embodiment. It is a timing chart of an embodiment. It is a processing flowchart of other embodiments.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1. Basic Overall Configuration of System First, the basic overall configuration of an electric vehicle will be described by taking a hybrid vehicle as an example.

  FIG. 1 shows a basic overall configuration. The system includes a battery 10 as a power source, system main relays SMR1 and 2, a filter capacitor 14, a converter 20, a smoothing capacitor 22, an inverter 24, a motor generator MG26, a hybrid (HV) ECU 54, and an MGECU 58. Consists of including. The filter capacitor 14, the converter 20, the smoothing capacitor 22, the inverter 24, and the MGECU 58 constitute a power control unit PCU. Note that the converter 20 is not necessarily indispensable, and may be configured without the converter 20.

  The battery 10 is composed of a nickel metal hydride battery, a lithium ion battery, or the like, and supplies a DC voltage and is charged by a DC voltage supplied from a drive system during regeneration.

  The HVECU 54 comprehensively controls the hybrid vehicle on the basis of outputs of various sensors indicating driving conditions and vehicle conditions, for example, sensor outputs such as accelerator opening and wheel speed.

  The PCU boosts the DC voltage from the battery 10 in accordance with a control command from the HVECU 54 during powering operation of the MG 26, and converts the boosted DC voltage into an AC voltage to drive and control the MG 26. Further, during regeneration of the MG 26, the PCU charges the battery 10 by converting the AC voltage generated by the MG 26 into a DC voltage in accordance with a control command from the HVECU 54.

  The SMRs 1 and 2 turn on / off the power supply path from the battery 10 to the inverter 24. SMR 1 is connected between the positive electrode of battery 10 and power supply line 100, and SMR 2 is connected between the negative electrode of battery 10 and power supply line 102. The SMRs 1 and 2 are each turned on / off by a control command from the HVECU 54.

  Converter 20 includes a step-up / step-down chopper circuit, and includes a reactor L, power semiconductor switching elements Q1 and Q2, and diodes D1 and D2. Switching elements Q1, Q2 are connected in series between power supply line 100 and power supply line 102. Reactor L is connected between SMR1 and a connection node of switching elements Q1, Q2. The current flowing through the reactor L is detected by the IL sensor 18. Reverse-arranged diodes D1 and D2 are connected between the emitters and collectors of switching elements Q1 and Q2, respectively, so that current flows from the emitter side to the collector side. A gate control signal is supplied to the gates of the switching elements Q1 and Q2, and the switching elements Q1 and Q2 are on / off controlled in response to the gate control signal. Converter 20 receives a voltage from battery 10 between power supply line 100 and power supply line 102, boosts the input voltage by switching operation of switching elements Q1 and Q2, and outputs a motor operating voltage for driving the motor. . The step-up ratio in converter 20 is determined according to the ON period ratio (duty ratio) of switching elements Q1 and Q2. Further, converter 20 steps down the regenerated voltage during regenerative braking and outputs it to battery 10. That is, the converter 20 is a bidirectional converter.

  MGECU 58 generates a voltage command value for the motor operating voltage based on the torque command value for MG 26 from HVECU 54, and determines the step-up ratio in converter 20 based on the generated voltage command value. Then, MGECU 58 outputs a gate control signal to switching elements Q1, Q2 so that this step-up ratio is realized.

  Smoothing capacitor 22 is connected between power supply line 101 and power supply line 102, smoothes the motor operating voltage output from converter 20 and supplies it to inverter 24.

  The inverter 24 converts the motor operating voltage into a three-phase alternating current and outputs it to the MG 26 that drives the wheels. Inverter 24 supplies power generated in MG 26 along with regenerative braking to converter 20. Inverter 24 includes switching elements Q <b> 3 to Q <b> 8 that constitute a U-phase arm, a V-phase arm, and a W-phase arm, which are arranged in parallel between power supply line 101 and power supply line 102. Although not shown, antiparallel diodes are connected between the collectors and emitters of the switching elements Q3 to Q8. An intermediate point of each phase arm of inverter 24 is connected to each phase end of each phase coil of MG 26 which is a three-phase permanent magnet motor. The other end of each phase coil is commonly connected to a neutral point. Current sensors 28 are provided in two of the three phases, and current is detected. For example, current sensors 28 are provided for the V phase and the W phase, respectively, and the V phase current and the W phase current are detected. The current sensor 28 outputs the detected current to the MGECU 58. In the present embodiment, the configuration in which the current sensor 28 is provided in two of the three phases is illustrated, but a configuration in which the current sensor 28 is provided in each of the three phases may be employed.

  The HVECU 54 generates an operation command for the MG 26 and outputs it to the MGECU 58 so that desired driving force generation and power generation are executed based on outputs from various sensors. The operation command includes an operation prohibition / permission of the MG 26 and a torque command value.

  The MGECU 58 controls the switching elements Q3 to Q8 so that the MG26 operates according to the operation command from the HVECU 54 by feedback control based on the current from the current sensor 28 provided in the PCU and the rotor rotation angle of the MG26 detected by the resolver. Controls the switching operation. Further, MGECU 58 generates a voltage command value of the motor operating voltage for increasing the efficiency of MG 26 based on the operation command from HVECU 54, and determines the step-up ratio in converter 20. Further, MGECU 58 controls converter 20 so as to step down the DC voltage supplied from inverter 24 during regenerative braking.

  Next, processing when the hybrid vehicle collides in the basic configuration as described above will be described.

2. FIG. 2 is a functional block diagram of the system. In addition to the above-described current sensor 28, HVECU 54, and MGECU 58, a G sensor 50, an airbag (A / B) ECU 52, and an electronically controlled brake system (ECB) 56 are provided.

  The G sensor 50 detects the acceleration at the time of collision and outputs it to the A / BECU 52.

  The A / BECU 52 operates the airbag based on the collision detection signal from the G sensor. Further, the A / BECU 52 outputs a collision detection signal to the HVECU 54.

  In response to this collision detection signal, the HVECU 54 outputs a control signal to the ECB 56 to operate the ECB 56 and maximize the brake.

  On the other hand, a detection signal from the current sensor 28 or the IL sensor 18 that detects a current flowing through the reactor L of the converter 20 is supplied to the MGECU 58. The MGECU 58 determines whether the current detected by the current sensor 28 (regenerative current) or the current detected by the IL sensor (regenerative current) is less than a predetermined value. The predetermined value is defined as a value experimentally found that welding occurs when the SMRs 1 and 2 are turned off when more current flows, that is, a threshold at which welding occurs in the SMRs 1 and 2. Alternatively, the predetermined value is defined as a value that can be regarded as substantially zero if the value is a value near zero and a value smaller than this value. When the detected regenerative current is less than the predetermined value, the MGECU 58 outputs a message to that effect to the HVECU 54.

  The HVECU 54 receives a collision detection signal from the A / BECU 52 and receives a signal for detecting that the regenerative current is less than a predetermined value from the MGECU 58, so as to turn off the SMRs 1 and 2 Is output. Further, the HVECU 54 outputs a discharge command for the filter capacitor 14 and the smoothing capacitor 22 to the MGECU 58 at the same time as the shutoff command for the SMRs 1 and 2. When receiving the discharge command, the MGECU 58 performs switching control of, for example, the switching elements Q3 to Q8 of the inverter 24 in order to discharge the filter capacitor 14 and the smoothing capacitor 22. Specifically, the MGECU 58 controls the inverter 24 so that the q-axis current does not flow through the MG 26, and the capacitor MG 26 consumes the charges of the filter capacitor 14 and the smoothing capacitor 22.

  When the wheel is idle at the time of the collision, and this idle wheel is a driving wheel, the counter electromotive voltage of the MG 26 is supplied to the battery 10 via the inverter 24. If the SMRs 1 and 2 are turned off before the rotation of the drive wheels stops, the SMRs 1 and 2 are welded and the filter capacitor 14 and the smoothing capacitor 22 cannot be discharged. However, as in the present embodiment, by detecting that the regenerative current is less than a predetermined value at the time of collision, the SMRs 1 and 2 are turned off to prevent welding of the SMRs 1 and 2, and the filter capacitor 14 and the smoothing capacitor. 22 can be reliably discharged. Further, in the case where there is a possibility that SMRs 1 and 2 are welded, it is necessary to shift to the discharge processing of the filter capacitor 14 and the smoothing capacitor 22 after confirming that the SMRs 1 and 2 are not welded. Then, since the SMRs 1 and 2 are turned off in a situation where the SMRs 1 and 2 are not likely to be welded, it is possible to start the discharge processing of the filter capacitor 14 and the smoothing capacitor 22 at the same time as turning off the SMRs 1 and 2. That is, it is possible to simultaneously output the SMR1 and 2 cutoff commands and the filter capacitor 14 and smoothing capacitor 22 discharge commands. Furthermore, in the present embodiment, it is configured to forcibly stop the driving wheel by operating the ECB 56 in response to the collision detection, so that the regenerative current can be quickly made less than a predetermined value after the collision, As a result, the high voltage system can be quickly stepped down to a certain voltage or less by the discharge treatment of the filter capacitor 14 and the smoothing capacitor 22.

  The shutoff command for SMR 1 and 2 and the discharge command for the filter capacitor 14 and the smoothing capacitor 22 are simultaneously output from the HVECU 54, but the MGECU 58 receives the discharge command for the filter capacitor 14 and the smoothing capacitor 22, for example, Since there is a certain time lag until switching control of the switching elements Q3 to Q8 is performed, the discharging process of the smoothing capacitor 22 is actually executed after the SMRs 1 and 2 are turned off in response to the cutoff command.

  FIG. 3 shows a processing flowchart at the time of collision in the present embodiment. First, the acceleration G at the time of collision is detected by the G sensor 50 (S101). The G sensor 50 transmits a detection signal to the A / BECU 52 (S102). The A / BECU 52 operates the airbag according to the detection signal and transmits a collision detection signal to the HVECU 54 (S103). The HVECU 54 receives the collision detection signal, transmits a control signal to the ECB 56, operates the brake to the maximum extent, and stops the wheel (S104).

  On the other hand, in parallel with this, the regenerative current detected by the current sensor 28 or the IL sensor 18 is supplied to the MGECU 58, and the MGECU 58 determines whether or not the detected regenerative current is smaller than a predetermined value (S105). If the regenerative current is less than the predetermined value, a signal to that effect is transmitted to the HVECU 54. When the HVECU 54 receives a signal indicating that the regenerative current is less than the predetermined value from the MGECU 58, the HVECU 54 simultaneously outputs a cutoff command for the SMRs 1 and 2 and a discharge command for the filter capacitor 14 and the smoothing capacitor 22 (S106). The cutoff commands for SMR 1 and 2 are supplied to SMR 1 and 2, and the discharge commands for filter capacitor 14 and smoothing capacitor 22 are supplied to MGECU 58. The SMRs 1 and 2 are quickly turned off in response to a cutoff command from the HVECU 54 (S107). Further, the MGECU 58 performs switching control of, for example, the inverter 24 according to the discharge command, and discharges the accumulated charge of the smoothing capacitor 22 by the MG 26 (S108). The filter capacitor 14 is also discharged together with the smoothing capacitor 22.

  FIG. 4 shows a timing chart of the present embodiment. FIG. 4A shows the detection timing of the G sensor, and it is assumed that a collision G is detected at a certain time. FIG. 4B shows the operation timing of the ECB 56, and the ECB 56 is switched from OFF to ON in response to this collision. 4 (c) and 4 (d) are control command timings from the HVECU 54, FIG. 4 (c) is a cutoff command for the SMRs 1 and 2, and FIG. 4 (d) is a timing for the discharge command for the filter capacitor 14 and the smoothing capacitor 22. It is. When the G sensor detects a collision G and the ECB 56 applies a brake to stop or slows down the rotation of the drive wheels to a state close to stopping, the regenerative current becomes less than a predetermined value, and at this timing, the shutoff command for SMR1 and 2 is turned on. At the same time, the discharge command for the filter capacitor 14 and the smoothing capacitor 22 is also turned on. FIG. 4E shows the off timing of the SMRs 1 and 2, and the SMRs 1 and 2 are quickly turned off in response to the shut-off command. Since it has been confirmed that the current flowing through the SMRs 1 and 2 is less than a predetermined value, the current is surely turned off without fear of welding. FIG. 4 (f) shows the discharge timing of the filter capacitor 14 and the smoothing capacitor 22, and the discharge is started at almost the same timing as SMR1 and SMR2 OFF or slightly later.

  As described above, in the present embodiment, it is determined that the regenerative current is less than the predetermined value after the collision, and if it is less than the predetermined value, the SMRs 1 and 2 are immediately turned off and the filter capacitor 14 and the smoothing capacitor 22 are discharged. Therefore, it is possible to shorten the total time from when the collision occurs until the discharge is completed. Further, in the present embodiment, when a collision is detected, the ECB 56 is operated to forcibly stop the driving wheel. Therefore, even if the driving wheel idles during a collision and the regenerative current flows more than a predetermined value, the regenerative current is quickly Therefore, it is possible to ensure that the SMRs 1 and 2 are turned off and the filter capacitor 14 and the smoothing capacitor 22 are discharged early. According to the present embodiment, when the ECB 56 is not operated at the time of a collision, the time until the discharge of the filter capacitor 14 and the smoothing capacitor 22 is completed is about 1 second. Can be shortened to, for example, about 0.5 seconds.

3. Other Embodiments In the above embodiment, when the collision G is detected by the G sensor 50, the ECB 56 is operated to stop the drive wheel. It is also possible to operate the ECB 56 when the regenerative current is not less than the predetermined value.

  FIG. 5 shows a processing flowchart in this case. First, the acceleration G at the time of collision is detected by the G sensor 50 (S201). The G sensor 50 transmits a detection signal to the A / BECU 52 (S202). The A / BECU 52 operates the airbag according to the detection signal and transmits a collision detection signal to the HVECU 54 (S203).

  On the other hand, in parallel with this, the regenerative current detected by the current sensor 28 or the IL sensor 18 is supplied to the MGECU 58, and the MGECU 58 determines whether or not the detected regenerative current is smaller than a predetermined value (S204). If the regenerative current is less than the predetermined value, a signal to that effect is transmitted to the HVECU 54. When the HVECU 54 receives a signal indicating that the regenerative current is less than the predetermined value from the MGECU 58, the HVECU 54 simultaneously outputs a cutoff command for the SMRs 1 and 2 and a discharge command for the filter capacitor 14 and the smoothing capacitor 22 (S205). The cutoff commands for SMR 1 and 2 are supplied to SMR 1 and 2, and the discharge commands for filter capacitor 14 and smoothing capacitor 22 are supplied to MGECU 58. The SMRs 1 and 2 are quickly turned off in response to a cutoff command from the HVECU 54 (S206). Further, the MGECU 58 performs switching control of, for example, the inverter 24 according to the discharge command, and discharges the accumulated charge of the smoothing capacitor 22 by the MG 26 (S207). The filter capacitor 14 is also discharged together with the smoothing capacitor 22.

  If the regenerative current is greater than or equal to the predetermined value (NO in S204), the MGECU 58 transmits a signal to that effect to the HVECU 54. When the HVECU 54 receives a signal indicating that the regenerative current is greater than or equal to a predetermined value, the HVECU 54 operates the ECB 56 (S208). Then, it is determined again whether or not the regenerative current is less than a predetermined value (S204).

  With the above processing, the ECB 56 is activated when the regenerative current is greater than or equal to a predetermined value, and the drive wheels are quickly stopped to operate the brakes to the maximum, and the regenerative current is also quickly reduced to below the predetermined value. Then, the SMRs 1 and 2 are turned off, and the discharging process of the filter capacitor 14 and the smoothing capacitor 22 is executed.

4). Other Modifications Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications can be made.

  For example, in this embodiment, when the collision G is detected by the G sensor 50, it is transmitted to the A / BECU 52, and the A / BECU 52 is further transmitted to the HVECU 54, but when the G sensor 50 detects the collision G, it directly transmits to the HVECU 54. You may send it. Alternatively, the G sensor 50 may transmit to the HVECU 54 via an ECU other than the A / BECU 52. Furthermore, the occurrence of a collision may be detected by a sensor other than the G sensor.

  Further, in the present embodiment, as shown in the system configuration diagram of FIG. 1, the configuration has one MG 26, but may have a configuration having two MGs. The two MGs are driven by inverters connected to each. In this case, the current sensor 28 is provided for each of the two MGs, but the reactor current sensor 18 may be one. Therefore, by adopting a configuration in which the reactor current sensor 18 detects the regenerative current, it is possible to speed up the discharge processing of the filter capacitor 14 and the smoothing capacitor 22 with a simple configuration even in a system having two MGs. It becomes.

  In the present embodiment, the SMRs 1 and 2 are turned off when the regenerative current is less than the predetermined value. Of course, it is determined whether or not the regenerative current is 0. It goes without saying that 2 may be turned off. When the regenerative current is 0, this is one aspect when the regenerative current is less than a predetermined value.

  Further, in the present embodiment, the collision G is detected by the G sensor 50. However, the collision is an example, and in the present embodiment, an arbitrary running abnormality other than the collision is detected, and the SMRs 1 and 2 are turned off. The present invention can be similarly applied to the process of discharging the capacitor 22. In short, the present invention can be applied to any case where a running abnormality occurs and the voltage of the high voltage system needs to be quickly reduced.

  Further, in the present embodiment, the drive wheel is stopped by the ECB 56, but the ECB 56 is one means for applying a brake to the wheel, and any means for stopping the wheel can be used.

  10 battery, 20 converter, 22 smoothing capacitor, 24 inverter, 26 motor generator (M / G), 54 hybrid ECU (HVECU), 58 motor generator ECU (MGECU), SMR1, system main relay.

Claims (4)

A control device for an electric vehicle that supplies electric power from a battery to a drive motor via a system main relay and a capacitor,
An abnormality detecting means for detecting an abnormal running of the electric vehicle including a collision;
Current detection means for detecting a regenerative current flowing in the system main relay when a running abnormality is detected by the abnormality detection means;
When the threshold value at which the system main relay is welded is set to a predetermined value, and the regenerative current detected by the current detection means is greater than or equal to a predetermined value, the system main relay is maintained in an on-control and is less than the predetermined value Control means for controlling the system main relay to be turned off and discharging the capacitor;
An electric vehicle control device comprising: The apparatus of claim 1.
An electric vehicle control device comprising: an operating means for operating a brake for stopping a drive wheel of the electric vehicle when a running abnormality is detected by the abnormality detecting means. The apparatus of claim 1.
An electric vehicle control device comprising: an operating means for operating a brake for stopping a drive wheel of the electric vehicle when a regenerative current detected by the current detection means is a predetermined value or more. In the apparatus in any one of Claims 1-3,
The control device outputs an off command for controlling off the system main relay and a discharge command for controlling discharge of the capacitor at the same time.

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