JP6686743B2 - Electric vehicle - Google Patents

Description

  The present specification discloses an electric vehicle. The electric vehicle includes a hybrid vehicle including an engine and a traveling motor, and an electric vehicle that travels with the traveling motor. A fuel cell vehicle is also included in the electric vehicle in this specification.

  As illustrated in FIG. 1, the voltage of the battery 3 is boosted by the converter 6, the boosted direct current is converted into a three-phase current by the inverter 7, and the converted three-phase current is supplied to the motor 13 to drive the electric vehicle. Being developed. Reference numeral 4 is an SMR (system main relay) composed of a relay inserted in the pre-boosting high potential line 20 and a relay inserted in the pre-boosting low potential line 22, and both relays are turned on at the same time.・ Turn off. A capacitor C1 is inserted between the pre-boosting high potential line 20 and the pre-boosting low potential line 22 to smooth the potential difference between the two. A capacitor C2 is inserted between the boosted high potential line 24 and the boosted low potential line 26 to smooth the potential difference between the two.

  The converter 6 and the inverter 7 have a plurality of built-in switching elements, and it is necessary to control ON / OFF of these switching elements. Reference numeral 9 is an MG-ECU (Motor Generator-Electronic Control Unit) that sends a control signal to these switching elements. The electric vehicle includes, in addition to the MG-ECU 9, an HV-ECU (Hybrid Vehicle-Electronic Control Unit) 8 that integrally controls the entire electric vehicle. The SMR 4 is controlled by the HV-ECU 8. A signal can be transmitted between the MG-ECU 9 and the HV-ECU 8 by a communication line 28.

  During traveling, the voltage of the battery 3 is applied to the capacitor C1 and the boosted voltage is applied to the capacitor C2. When the electric vehicle collides, a process of discharging the electric charges of the capacitors C1 and C2 is executed.

  Reference numeral 10 in FIG. 1 denotes a collision detection sensor. In the case of FIG. 1, when a collision occurs, a collision detection signal is sent to the MG-ECU 9 via the communication line 30, and further via the communication line 28. It is sent from the MG-ECU 9 to the HV-ECU 8. When a collision occurs, the HV-ECU 8 turns off the SMR 4 and disconnects the capacitors C1 and C2 from the battery 3. Further, MG-ECU 9 controls converter 6 or inverter 7 to discharge the charges of capacitors C1 and C2. Various techniques for controlling the converter 6 or the inverter 7 so that the capacitors C1 and C2 are discharged have been developed and are disclosed in Patent Documents 1 to 3.

JP, 2014-204627, A JP, 2014-125127, A JP, 2011-036048, A

  In the case of the system of FIG. 1, the collision detection signal is sent from the MG-ECU 9 to the HV-ECU 8 via the communication line 28. If an abnormality occurs in the communication line 28 due to the collision, the collision detection signal does not reach the HV-ECU 8, so that the SMR 4 is not turned off. If the SMR 4 is not turned off, even if the MG-ECU 9 tries to discharge the capacitors C1 and C2 by the converter 6 or the inverter 7, the capacitors C1 and C2 do not discharge as intended. The MG-ECU 9 and the HV-ECU 8 are arranged in the engine compartment, and the communication line 28 extends in the engine compartment. It is difficult to protect the communication line 28 from all kinds of collisions, and there is a possibility that the communication line 28 may become abnormal due to the collision.

  In Patent Documents 1 to 3, it is described that when the collision detection sensor 10 transmits a collision detection signal, the collision detection signal is transmitted to the HV-ECU 8 and the SMR 4 is turned off. Although the transmission path of the collision detection signal is not necessarily explained clearly, if the collision detection signal is transmitted to the HV-ECU 8 via the MG-ECU 9, the above-mentioned problem occurs. The collision detection signal may be transmitted to the MG-ECU 9 via the HV-ECU 8. In that case, if an abnormality occurs in the communication line connecting the HV-ECU 8 and the MG-ECU 9, there is a problem that the collision detection signal is not transmitted to the MG-ECU 9. If the collision detection sensor 10 and the MG-ECU 9 are not only connected by a communication line, but the collision detection sensor 10 and the HV-ECU 8 are also connected by another communication line, communication between the HV-ECU 8 and the MG-ECU 9 is performed. Due to the abnormality, there is no problem that the discharge process of the capacitors C1 and C2 becomes disordered. However, a method of connecting the collision detection sensor 10 to the HV-ECU 8 via the MG-ECU 9 (referred to as the former) and a method of connecting the collision detection sensor 10 to the MG-ECU 9 and the HV-ECU 8 in parallel (referred to as the latter). Comparing the two, the former method is simpler, and it is necessary to maintain the former method.

  In this specification, the collision detection sensor 10 is connected to the HV-ECU 8 via the MG-ECU 9, and the collision detection signal is the HV even when an abnormality occurs in the communication line connecting the MG-ECU 9 and the HV-ECU 8. A technique will be disclosed in which the HV-ECU 8 turns off the SMR 4 when it reaches the ECU 8 and a collision occurs.

  In the electric vehicle disclosed in the present specification, the battery and the converter are connected by the pre-boosting high potential line and the pre-boosting low potential line, and the converter and the inverter are connected by the boosted high potential line and the boosted low potential line. And the inverter is connected to the motor. SMR (System Main Relay) is inserted between the high potential line before boosting and the low potential line before boosting, and the first capacitor is inserted between the high potential line before boosting and the low potential line before boosting. The second capacitor is inserted between the potential line and the boosted low potential line. The converter and the inverter are controlled by the MG-ECU (Motor Generator-Electronic Control Unit), the SMR is controlled by the HV-ECU (Hybrid Vehicle-Electronic Control Unit), and the collision detection sensor is connected to the MG-ECU by the first communication line. The MG-ECU is connected to the HV-ECU by the second communication line, and a current sensor that detects a current is installed on the pre-boosting high potential line or the pre-boosting low potential line. When a collision detection signal is input to the MG-ECU from the collision detection sensor, a switching procedure for switching the control procedure of the converter from the normal procedure to the collision procedure, and a first capacitor and a second capacitor in the converter or the inverter. There is prepared a processing procedure for executing a discharging procedure for discharging. A processing procedure for the HV-ECU to determine whether the variation pattern of the current sensor is a normal pattern or a collision pattern, and a processing procedure to turn off the SMR when the determination result of the processing procedure changes from the normal pattern to the collision pattern. Is prepared.

  In this electric vehicle, when a collision is detected, a collision detection signal is first input to the MG-ECU. When the collision detection signal is input to the MG-ECU, the MG-ECU switches the converter control procedure from the normal procedure to the collision procedure. As a result, the current value measured by the current sensor changes to a fluctuation pattern (collision pattern) different from the normal pattern. The HV-ECU turns off the SMR when detecting this variation pattern.

  According to the above-described technique, the occurrence of collision can be transmitted to the HV-ECU even when an abnormality occurs in the communication line connecting the MG-ECU and the HV-ECU. Even if an abnormality occurs in the communication line connecting the MG-ECU and the HV-ECU, the SMR can be reliably turned off, so that the discharge control of the capacitor can be reliably and safely performed in the event of a vehicle collision.

It is a block diagram for explaining the electric power system of the conventional electric vehicle. It is a block diagram of the electric power system of the electric vehicle of an Example. It is a flow chart of electric discharge control.

  A hybrid vehicle 2 that is an electric vehicle of the embodiment will be described with reference to the drawings. FIG. 2 shows a block diagram of the electric power system of the hybrid vehicle 2. The hybrid vehicle 2 includes an engine 11 and a three-phase AC motor 13 (hereinafter referred to as the motor 13) for traveling. The output of the engine 11 and the output of the motor 13 are combined by the power distribution mechanism 12 and transmitted to the axle 14. The power distribution mechanism 12 may distribute the output of the engine 11 to the axle 14 and the motor 13. In that case, the hybrid vehicle 2 is driven by the power of the engine 11 and is generated by the motor 13. The generated electric power charges the battery 3 described later. Further, the hybrid vehicle 2 may use the kinetic energy of the vehicle during braking to reversely drive the motor 13 to generate electric power and charge the battery 3 with the electric power.

  The hybrid vehicle 2 includes a power control device 5 (hereinafter, also referred to as a PCU (Power Control Unit) 5), an SMR 4 and a battery 3. The PCU 5 converts the DC power of the vehicle-mounted battery 3 into three-phase AC power having an appropriate frequency and supplies it to the motor 13. In other words, the PCU 5 converts the power of the battery 3 into the drive power of the motor 13. The battery 3 and the PCU 5 are connected via the SMR 4.

  The PCU 5 includes therein a converter 6, an inverter 7, a first capacitor C1, a second capacitor C2, and an MG-ECU 9. The converter 6 is connected to the battery 3 via a pre-boosting high potential line 20 and a pre-boosting low potential line 22. The converter 6 has both functions of boosting the voltage of the battery 3 and supplying it to the inverter 7, and reducing the regenerative power sent from the inverter 7 and supplying it to the battery 3. That is, the converter 6 is a bidirectional DC-DC converter. The converter 6 includes a reactor L1, two switching elements s7 and s8, and a diode connected in antiparallel to each switching element. The converter 6 shown in FIG. 2 is well known and will not be described in detail.

  Inverter 7 is connected to converter 6 via boosted high potential line 24 and boosted low potential line 26. The inverter 7 converts the DC power of the battery 3 supplied through the converter 6 into three-phase AC power and supplies the three-phase AC power to the motor 13. When the driver steps on the brake pedal, the inverter 7 converts the AC power generated by the reverse driving of the motor 13 into DC power and supplies the DC power to the converter 6. The inverter 7 has a configuration in which a pair of two switching elements connected in series is connected in parallel in three sets (s1 and s4, s2 and s5, s3 and s6). A diode is connected in antiparallel to each switching element. Three-phase alternating current phases (U phase, V phase, W phase) are output from between the three sets of series circuits. The inverter 7 shown in FIG. 2 is well known and will not be described in detail. In the following, in the circuit of the inverter 7, the current path on the high potential side is referred to as an “upper arm”, and the current path on the low potential side is referred to as a “lower arm”.

  The first capacitor C1 is inserted between the potential line 20 and the potential line 22. The first capacitor C1 is connected in parallel with the converter 6. The first capacitor C1 is provided to remove a noise component superimposed on the output current of the battery 3. That is, the first capacitor C1 smoothes the potential difference between the potential line 20 and the potential line 22.

  The second capacitor C2 is inserted between the potential line 24 and the potential line 26. The second capacitor C2 is connected in parallel between the converter 6 and the inverter 7. The second capacitor C2 is provided to remove a noise component that is superimposed on the output current of the converter 6 (current supplied from the battery 3). That is, the potential difference between the potential line 24 and the potential line 26 is smoothed by the second capacitor C2.

  The MG-ECU 9 generates a pulse signal to be sent to the converter 6 and the inverter 7, and controls ON / OFF of each of the switching elements s1 to s8. The broken line arrow shown in FIG. 2 shows a part of the signal line. The hybrid vehicle 2 determines the torque value to be output by the motor 13 based on the information from the driver (accelerator opening degree, etc.) and vehicle speed information. MG-ECU 9 controls converter 6 and inverter 7 based on the torque value. Further, as will be described later, MG-ECU 9 stores the charge of first capacitor C1 and second capacitor C2 in converter 6 or inverter 7 and switching unit 9a that switches the control procedure of converter 6 from the normal procedure to the collision procedure. The discharge processing unit 9b is provided for executing the processing for discharging. Note that in FIG. 2, only signal lines to some switching elements are shown and signal lines to other switching elements are omitted.

  The hybrid vehicle 2 also includes a collision detection sensor 10, an HV-ECU 8, and a current sensor 15.

  The collision detection sensor 10 detects a vehicle collision. The collision detection sensor 10 is connected to the MG-ECU 9 by the first communication line 30. That is, the collision detection sensor 10 can communicate with the MG-ECU 9 via the first communication line. As the collision detection sensor 10, for example, an airbag sensor or a pre-crash sensor is used. The airbag sensor is a sensor that detects the impact of a vehicle collision, and is mainly used to operate the airbag when the vehicle collides. On the other hand, the pre-crash sensor is a sensor that detects a high probability that the vehicle will collide with an object in front. The probability that a vehicle will collide is comprehensively determined based on information from, for example, a camera mounted on the vehicle, a radar that measures an inter-vehicle distance, and information on a running state such as a vehicle speed. A system including a device such as a camera or a radar and a CPU that calculates information may be referred to as a pre-crash sensor. In the present specification, if the probability of a vehicle collision is high, a collision will result. Therefore, a sensor (pre-crash sensor) that detects a high probability of a vehicle collision is also referred to as "detects a vehicle collision. It is included in the sensor.

  The HV-ECU 8 controls ON / OFF of the SMR 4. The HV-ECU 8 is connected to the MG-ECU 9 by the second communication line 28. That is, the HV-ECU 8 can communicate with the MG-ECU 9 via the second communication line 28. When the SMR 4 is on, the battery 3 and the PCU 5 are electrically connected, and when the SMR 4 is off, the battery 3 and the PCU 5 are electrically disconnected. Further, as will be described later, the HV-ECU 8 includes a discrimination processing unit 8a that discriminates the variation pattern of the current sensor 15, and an SMR processing unit 8b that turns off the SMR 4 based on the result of the discrimination processing unit 8a.

  The current sensor 15 measures the current value of the battery 3. In this embodiment, the current sensor 15 is arranged on the potential line 20 on the battery 3 side of the SMR 4. The current sensor 15 may be arranged on the potential line 22 on the battery 3 side of the SMR 4.

  The motor 13 is required to have a high output in order to drive the hybrid vehicle 2. Therefore, in the hybrid vehicle 2, the voltage of the battery 3 is boosted to several hundreds of volts by the converter 6 and supplied to the motor 13 via the inverter 7. That is, a large current flows through the PCU 5 that supplies electric power to the motor 13. Therefore, a large amount of electric charge is stored in the capacitors C1 and C2 provided in the PCU 5, especially the second capacitor C2. When the vehicle collides, it is desirable to discharge the electric charge accumulated in the capacitors C1 and C2 in order to ensure the safety of the driver and the worker. Hereinafter, discharge control of capacitors C1 and C2 by MG-ECU 9 and HV-ECU 8 will be described.

  FIG. 3 is a flowchart showing a process in which the discharge control is executed. First, the MG-ECU 9 determines whether or not a collision detection signal is acquired from the collision detection sensor 10 (S2). When the MG-ECU 9 acquires the collision detection signal (S2: YES), the switching unit 9a switches the pulse signal pattern to be transmitted to the switching elements s7 and s8, and switches the control procedure of the converter 6 from the normal procedure to the collision procedure. (S4). The switching of the control procedure includes, for example, changing the operating frequency of the switching element. At this time, the current sensor 15 measures the current value of the collision pattern different from the normal pattern. The HV-ECU 8 observes the output pattern of the current sensor 15 by the discrimination processing unit 8a (S6), and when the pattern changes from the normal pattern to the collision pattern (S8: YES), the SMR processing unit 8b. Turns off the SMR4 (S10). When the MG-ECU 9 changes the operating frequency during a vehicle collision, the changing speed of the current sensor 15 changes, so that the HV-ECU 8 can detect the change from the normal pattern to the collision pattern.

  Next, MG-ECU 9 determines whether or not the current rotation speed of motor 13 is lower than the dischargeable rotation speed (S12). When the collision detection sensor 10 detects a vehicle collision, the hybrid vehicle 2 is not always stopped. Therefore, the motor 13 may be rotating. Further, the motor 13 may be idling due to the drive shaft coming off during a collision. In these cases, the counter electromotive force is generated in the motor 13 by the rotation of the motor 13. Since this counter electromotive force is applied to the capacitor, discharge control is performed until the discharge speed of the capacitor exceeds the charging speed by the counter electromotive force (that is, until the rotation speed of the motor 13 becomes slower than the dischargeable rotation speed). I can't. When the rotation speed of the motor 13 is equal to or higher than the dischargeable rotation speed (S12: NO), the MG-ECU 9 turns on the switching elements s1-s3 of the upper arm of the inverter 7 and turns off the switching elements s4-s6 of the lower arm. Yes (S11). As a result, the electromagnetic brake is applied to the motor 13. The current generated at this time flows through a plurality of current paths connecting each phase and the switching elements s1-s3.

  When the rotation speed of the motor 13 is lower than the dischargeable rotation speed (S12: YES), the MG-ECU 9 switches the pulse signal to be transmitted to the switching elements s7, s8 by the switching unit 9a, and performs the procedure at the time of collision of the converter 6. Control to cancel is performed (S14). In the process of step S10, control for canceling the collision procedure of converter 6 may be performed, and MG-ECU 9 may stop converter 6 or may switch to the normal procedure.

  Next, the MG-ECU 9 controls the converter 6 and / or the inverter 7 by the discharge processing unit 9b so as to discharge the charges of the capacitors C1 and C2 (S16). Specifically, the discharge control of the capacitors C1 and C2 by controlling the converter 6 is as follows, for example. MG-ECU 9 turns on switching element s7 of converter 6 and turns off switching element s8. As a result, the electric charge of the second capacitor C2 can be discharged through the current path passing through the switching element s7 and the reactor L1. Also, the MG-ECU 9 turns off the switching element s7 and turns on the switching element s8. As a result, the electric charge of the first capacitor C1 can be discharged through the current path passing through the reactor L1 and the switching element s8.

  Further, the discharge control of the capacitor by controlling the inverter 7 is as follows, for example. The MG-ECU 9 (discharge processing unit 9b) controls the switching elements s1 to s6 of the inverter 7 so that the motor 13 operates at an angular magnetic angle such that electric power is consumed without generating torque in the motor 13. By doing so, the electric charge of the capacitor can be discharged. It should be noted that either one of the control of the converter 6 or the control of the inverter 7 may be used alone to discharge the capacitor, or both controls may be used simultaneously.

  When the discharging of the capacitors C1 and C2 is completed (S18), the MG-ECU 9 and the HV-ECU 8 end the discharge control process.

  As described above, in the hybrid vehicle 2 of the embodiment, when the collision detection sensor 10 detects a collision, first, the collision detection signal is input to the MG-ECU 9. When the collision detection signal is input to MG-ECU 9, MG-ECU 9 switches the control procedure of converter 6 from the normal procedure to the collision procedure. Along with this, the current value measured by the current sensor 15 shows a variation pattern (a collision pattern) different from the normal pattern. The HV-ECU 8 turns off the SMR 4 when detecting this variation pattern.

  Therefore, the presence or absence of a collision can be transmitted to the HV-ECU 8 without using the second communication line 28 that connects the MG-ECU 9 and the HV-ECU 8. Therefore, even if an abnormality occurs in the second communication line, the SMR 4 can be surely turned off, so that the discharge control of the subsequent capacitors C1 and C2 can be safely performed even during a vehicle collision. .

  The points to be noted regarding the embodiment will be described. In the process of step S7 of FIG. 3, the switching elements s4-s6 of the lower arm may be turned on and the switching elements s1-s3 of the upper arm may be turned off. In this way, the current generated by the rotation of the motor 13 can be passed through the switching elements s4-s6.

  Further, the embodiment discloses the technique of turning off the SMR 4 when an abnormality occurs in the second communication line 28. When no abnormality has occurred in the second communication line 28, the HV-ECU 8 and the MG-ECU 9 communicate with each other through the communication, so that the SMR 4 can be turned off.

  The hybrid vehicle of the embodiment corresponds to an example of “electric vehicle” in the claims. The discrimination processing unit of the embodiment corresponds to an example of the "procedure for discriminating whether the variation pattern of the current sensor is the normal pattern or the collision pattern" in the claims. The SMR processing unit of the embodiment corresponds to an example of a "procedure for turning off SMR" in the claims. The switching unit of the embodiment corresponds to an example of "switching procedure of converter control procedure from normal procedure to collision procedure". The discharge treatment section of the embodiment corresponds to an example of the “processing procedure for executing the discharge procedure” in the claims.

Specific examples of the present invention have been described above in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
The technical elements described in the present specification or the drawings exert technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and the technical utility is exhibited by achieving one of the objects.

2: Hybrid vehicle 3: Battery 4: SMR
5: Power control device 6: Converter 7: Inverter 8: HV-ECU
8a: Discrimination processing unit 8b: SMR processing unit 9: MG-ECU
9a: Switching unit 9b: Discharge processing unit 10: Collision detection sensor 13: Motor 15: Current sensor 20: High potential line before boost 22: Low potential line before boost 24: High potential line after boost 26: Low potential line after boost 28 : Second communication line 30: first communication line C1: first capacitor C2: second capacitor

Claims (1)

The battery and the converter are connected by the high potential line before boosting and the low potential line before boosting,
The converter and the inverter are connected by a boosted high potential line and a boosted low potential line,
The inverter is connected to a motor,
SMR (System Main Relay) is inserted in the pre-boosting high potential line and the pre-boosting low potential line,
A first capacitor is inserted between the pre-boosting high potential line and the pre-boosting low potential line,
A second capacitor is inserted between the boosted high potential line and the boosted low potential line,
The converter and the inverter are controlled by an MG-ECU (Motor Generator-Electronic Control Unit),
The SMR is controlled by an HV-ECU (Hybrid Vehicle-Electronic Control Unit),
A collision detection sensor is connected to the MG-ECU by a first communication line,
The MG-ECU is connected to the HV-ECU by a second communication line,
A current sensor for detecting a current is installed on the pre-boosting high potential line or the pre-boosting low potential line,
When a collision detection signal from the collision detection sensor is input to the MG-ECU, a switching procedure for switching the control procedure of the converter from the normal procedure to the collision procedure when the collision detection signal is input to the MG-ECU; A processing procedure for executing a discharging procedure for discharging the first capacitor and the second capacitor is prepared,
A processing procedure for the HV-ECU to determine whether the variation pattern of the current sensor is a normal pattern or a collision pattern, and the SMR is turned off when the determination result of the processing procedure changes from the normal pattern to the collision pattern. There is a processing procedure to
Drive system for electric vehicles.

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