JP2007168680A - Drive control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive control device capable of preventing the thermal breakdown of an inverter circuit, in a hybrid vehicle or an electric automobile. <P>SOLUTION: When a vehicle 1 stops, a motor ECU10 calculates an elapsed time until getting to a stop state by a vehicle speed sensor 18 detecting the speed and input of a brake torque signal from a brake ECU20. An electric angle of the stop state is estimated from the calculated result and the input of an electric current detecting device 60 detecting the electric angle of a driving current. The estimated electric angle is compared with a set electric angle. In the case that the vehicle is estimated to stop in the set electric angle, brake torque is controlled to control the electric angle of the driving current at the time of stopping to be an angle other than the set electric angle. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle drive control device, and more particularly to a vehicle drive control device that controls an inverter circuit that supplies electric power necessary for an electric motor.

  A hybrid vehicle or an electric vehicle can travel by the output of an electric motor driven by electric power. Upon receiving a torque command from an accelerator or the like, the drive control device controls the inverter circuit and supplies a drive current as necessary to the electric motor. The torque output from the electric motor driven by the current is transmitted to the drive wheels, the drive wheels rotate, and the vehicle travels.

  When the vehicle is climbing up or when the wheel is fitted in the recess, the running resistance torque on the uphill may be larger than the output torque of the electric motor according to the accelerator depression amount. At this time, the electric motor and the drive wheels are in a locked state where the rotation speed is zero. When in the locked state, a large current continuously flows through the switching element energized by the inverter circuit, and the temperature of the switching element rises. And there was a possibility that the switching element would cause thermal destruction.

  For example, the electric vehicle control apparatus described in Patent Document 1 below estimates the heat generation of the switching element by measuring the elapsed time thereafter and measuring the temperature sensor of the inverter circuit after being locked. Then, when each measured value exceeds the set value, the control device reduces the drive current and switches the switching element to which the inverter circuit is energized. Thereby, the said control apparatus suppresses heat_generation | fever of the switching element of an inverter circuit, and prevents thermal destruction.

JP 2001-177905 A JP 11-215687 A JP 2005-45863 A

  In the above-described prior art, thermal destruction is predicted based on the elapsed time of the locked state and the temperature in the inverter circuit. However, the prediction does not accurately grasp the heat generation of each switching element itself.

  An object of the present invention is to provide a vehicle drive control device capable of accurately grasping the state of each switching element and preventing thermal destruction of an inverter circuit.

  In order to solve the above-described problems, a drive control device of the present invention controls an inverter circuit to supply electric power necessary for an electric motor that drives a drive wheel of a vehicle, and an electric angle of a drive current of the electric motor. An electrical angle detecting means for detecting the electrical angle, an electrical angle predicting means for predicting an electrical angle when the vehicle is stopped based on the detected electrical angle, a comparing means for comparing the predicted electrical angle with the set electrical angle, and the prediction And a stop control means for stopping the vehicle so that the electrical angle is other than the set electrical angle.

  Further, the stop control means of the drive control device can also stop the vehicle by brake torque.

  Another drive control device of the present invention controls an inverter circuit in order to supply necessary electric power to an electric motor that drives a drive wheel of the vehicle. When the vehicle falls into a locked state, Lock detecting means for detecting the state; electrical angle detecting means for detecting the electrical angle of the drive current of the motor; comparing means for comparing the detected electrical angle with the set electrical angle; and the detected electrical angle and the set electrical angle. An electric angle control means for shifting the detected electric angle by changing the driving force of the electric motor when the angle coincides.

  Furthermore, the electrical angle control means of the drive control device can reduce the driving force of the electric motor to shift the electrical angle.

  Further, the set electrical angle of the drive control device of the present invention can be set to a range of 90 ° ± 5 ° and a range of 270 ° ± 5 ° for at least one phase.

  According to the present invention, it is possible to perform control to stop the vehicle other than the set electrical angle based on the detection result of the electrical angle of the drive current. As a result, even when the vehicle enters a locked state when starting, the maximum current is not concentrated on the switching element of at least one phase, and thermal destruction of the inverter circuit can be prevented.

  According to another invention of the present invention, when the detection result of the electrical angle of the drive current coincides with the set electrical angle, it is possible to control to change the drive force to shift from the set electrical angle. Thereby, even if the vehicle unexpectedly falls into a locked state, the maximum current is not concentrated on the switching element of at least one phase, and thermal destruction of the inverter circuit can be prevented.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the present embodiment, as an example, a mode in which an electric motor is included in a power source of a vehicle will be described. However, the present invention is not limited to this embodiment, and can be applied to a hybrid vehicle having an engine and an electric motor as a power source of the vehicle.

  FIG. 1 is a configuration diagram showing a schematic configuration of a vehicle according to an embodiment of the present invention. The vehicle 1 has an electric motor 40 (hereinafter referred to as a motor 40) as a power source. The motor 40 generates a rotational torque as a driving force on the output shaft based on the supplied electric power.

  The vehicle 1 also has a vehicle drive system 70 in order to transmit the rotational torque to drive wheels 80 (hereinafter referred to as tires 80). The vehicle drive system 70 includes a transmission 72 that decelerates the rotation input from the motor 40 and increases the torque, and a differential 74 that operatively transmits the input from the transmission 72 to the left and right tires 40. Have. Thereby, the vehicle drive system 70 can transmit the rotational torque from the motor 40 to the tire 40.

  The vehicle 1 also has an inverter circuit 50 that supplies power from the battery 30 to the motor 40. The inverter circuit 50 is controlled by a drive control device 10 (hereinafter referred to as a motor ECU 10) described later, converts DC power supplied from the battery 30 into desired AC power, and supplies it to the motor 40.

  The inverter circuit 50 will be described with reference to FIG. FIG. 2 is an electric circuit diagram connecting the battery, the inverter circuit, and the electric motor. The inverter circuit 50 includes semiconductor switching elements 50a to 50f such as IGBTs (Insulated Gate Bipolar Transistors). The inverter circuit 50 connects a capacitor 51 for stabilizing an input voltage between a positive electrode bus and a negative electrode bus connected to the battery 30, and connects two semiconductor switching elements in series for three phases. is doing. And the output to the motor for three phases is respectively taken out from the middle of the two semiconductor switching elements (each arm) connected in series.

  In the embodiment, the U-phase semiconductor switching elements are 50a and 50b, the V-phase semiconductor switching elements are 50c and 50d, and the W-phase semiconductor switching elements are 50e and 50f. Each of the semiconductor switching elements 50a to 50f is turned on / off in response to a torque command from the motor ECU 10. In this embodiment, a desired three-phase alternating current is output by performing PWM (pulse width modulation) control on each of the semiconductor switching elements 50a to 50f.

  Returning to the description of FIG. 1, the vehicle 1 includes a motor ECU 10 that controls the motor 40. The motor ECU 10 receives various signals from an accelerator sensor 14 for detecting an accelerator pedal depression amount, a shift sensor 16 for detecting an operation position of a shift lever, a brake sensor 12 for detecting a brake pedal depression amount, and a vehicle speed sensor 18. Based on these, a required torque that is a rotational torque to be output from the motor 40 is calculated based on these. Then, the motor ECU 10 generates a control signal for controlling on / off of each of the semiconductor switching elements 50a to 50f in the inverter circuit 50 based on the required torque and detection values of a rotation angle sensor 62 and a current detection device 60 described later. Output. Thereby, the rotational torque output from the motor 40 is adjusted to match the required torque. The motor ECU 10 is connected to a brake control device 20 (hereinafter referred to as a brake ECU 20), which will be described later, via a communication line, and can exchange various control signals and data.

  Further, the vehicle 1 has a rotation angle sensor 62 that is provided in the motor 40, for example, composed of a Hall element, and a current detection device 60 that is provided in a power line between the inverter circuit 50 and the motor 40. is doing. The rotation angle sensor 62 detects the rotational position of the rotor in the motor 40 and outputs the detection result to the motor ECU 10. Current detection device 60 detects the drive current of each phase supplied from inverter circuit 50 to motor 40, and outputs the detection result to motor ECU 10.

  Further, the vehicle 1 has a brake ECU 20. The brake ECU 20 receives a brake sensor 12 that detects the amount of depression of the brake pedal and a signal from the vehicle speed sensor 18, and a required brake torque is calculated based on these signals. Then, the brake ECU 20 outputs a control signal to the brake device 90 based on the required brake torque, and the brake device 90 applies a brake torque corresponding to the required brake torque to the tire 80.

  Next, the cause of the thermal breakdown of the inverter circuit 50 will be described with reference to FIG. FIG. 3 shows a waveform of a three-phase alternating current that is a drive current supplied to the motor 40, and the U phase, the V phase, and the W phase each have a phase difference of 120 degrees. Further, since the electrical angle of the waveform of the three-phase alternating current shown in FIG. 3 is determined according to the rotational angle of the rotor of the motor 40, there is a fixed relationship between them. When the vehicle 1 falls into the locked state, the rotational speeds of the motor 40 and the tire 80 become zero despite the torque command from the motor ECU 10. At this time, the waveform of the drive current stops at a certain electrical angle, and the current at that electrical angle flows continuously.

  When the continuously flowing current is a large current, the semiconductor switching element through which the current flows generates heat due to its own resistance. In particular, when the current value of the drive current is maximum, in other words, when the electrical angle of one phase is 90 degrees and 270 degrees, the semiconductor switching element has a high possibility of thermal destruction due to heat generation. Generally, when the electrical angle of one phase is in the range of 90 ° ± 5 ° or in the range of 270 ° ± 5 °, there is a possibility of thermal destruction. For example, even in the locked state, the semiconductor switching element does not cause thermal destruction due to heat generation.

  Next, the control operation of the motor ECU 10 when the vehicle 1 travels will be described. During traveling, the motor ECU 10 calculates a required torque from signals from the accelerator sensor 14, the shift sensor 16, and the vehicle speed sensor 18 at that time. Then, based on the calculation result, the semiconductor switching elements 50 a to 50 f of the inverter circuit 50 are controlled, and a driving current according to need is supplied to the motor 40. The phase of the drive current is adjusted according to information of the rotation angle sensor 62 and the current detector 60 of the drive current. Thus, the rotational torque of the motor 40 generated by the control operation of the motor ECU 10 is transmitted to the tire 80 via the vehicle drive system 70, and the vehicle 1 travels.

  Here, in the motor ECU 10, the electrical angle when the vehicle 1 is stopped is in an electrical angle range in which the inverter circuit 50 is not thermally destroyed in the locked state, that is, the electrical angle of one phase is 90 ° ± 5 °. And a range of 270 ° ± 5 ° (hereinafter referred to as a set electrical angle). Therefore, the motor EUC 10 receives a signal of a required brake torque from the vehicle speed sensor 18 that detects the speed of the vehicle 1 and the brake ECU 20, and calculates an elapsed time until the vehicle is stopped. Furthermore, the electrical angle in the stopped state is predicted based on the calculation result and the input of the current detection device 60 that detects the electrical angle of the drive current. Then, the motor ECU 10 compares the predicted electrical angle with the set electrical angle, and if it is predicted that the vehicle 1 will stop at the set electrical angle, the motor ECU 10 sends a request to the brake ECU 20 to change this. Supply. An adjustment pattern when a change request is input is prepared in advance, and the tire rotation angle when the vehicle stops is adjusted by controlling the brake torque according to the pattern, and the electrical angle of the drive current when stopping is adjusted. It is controlled other than the set electrical angle. As a pattern, for example, the required brake torque is changed slightly larger for a preset short time, and the driving current electric angle is controlled to a value other than the set electric angle by stopping the wheel rotation angle earlier by the amount shifted by the tire rotation angle. Etc. In addition, when the amount of brake depression is more than predetermined, it is also suitable to judge that it is an emergency and prohibit such control.

  As described above, even when the vehicle 1 is in a locked state when starting on an uphill road or the like, since the electrical angle of the drive current is other than the set electrical angle, the inverter circuit 50 can be prevented from being thermally destroyed.

  In the vehicle 1 of the embodiment, the detection of the electrical angle of the drive current is performed by the current detection device 60, but the electrical angle of the drive current and the rotation angle of the rotor of the motor 40 are in a fixed relationship, so The angle sensor 62 may be used. In the vehicle 1, processing for a series of control operations for stopping the vehicle other than the set electrical angle is performed by the motor ECU 10, but part or all of the processing may be performed by the brake ECU 20.

  Next, when the vehicle 1 unexpectedly falls into a locked state, for example, when the tire 80 is fitted in a bag during traveling, the control operation of the motor ECU 10 when the electrical angle of the drive current is the set electrical angle. Will be described.

  The motor ECU 10 determines the lock state based on the calculation result of the required torque and the output of the rotation angle sensor 62 that detects the rotation state of the motor 40. That is, the motor ECU 10 determines that the lock state is established when there is a required torque and the output of the rotation angle sensor 62 is 0 when the control signal is output to the inverter circuit 50 based on the required torque. The motor ECU 10 compares the electrical angle of the drive current with the set electrical angle, and performs control to prevent thermal destruction if the set electrical angle is met.

  First, the motor ECU 10 needs to rotate the motor 40 in order to remove the electrical angle of the drive current from the set electrical angle. Therefore, the motor ECU 10 outputs a control signal that slightly varies the drive current to the inverter circuit 50. Since the inverter circuit 50 varies the drive current by the control signal, the rotational torque of the motor 40 slightly varies. At this time, since the tire 80 is fixed to the heel, the tire 80 does not move with a slight change in the rotational torque. However, slight fluctuations in rotational torque are absorbed, for example, when the shaft in the vehicle drive system 70 between the motor 40 and the tire 80 is distorted. As a result, the motor 40 rotates slightly, and the electrical angle of the drive current deviates from the set electrical angle. Therefore, even if there is no change in the accelerator depression amount, the output of the motor 40 is changed, so that the electrical angle can be other than the set electrical angle.

  As described above, even if the vehicle 1 is unexpectedly locked, the motor ECU 10 controls the electrical angle of the drive current to a value other than the set electrical angle, so that the inverter circuit 50 can be prevented from being thermally destroyed.

  In the vehicle 1 of the embodiment, the rotation state of the motor 40 from the rotation angle sensor 62 is used as a determination element for the locked state, but a change in drive current from the current detection device 60 may be used as a determination element. Further, although the motor ECU 10 performs control for slightly varying the drive current, only control for slightly reducing the drive current and slightly removing the drive force may be performed.

1 is a configuration diagram illustrating a schematic configuration of a vehicle according to an embodiment of the present invention. It is an electric circuit diagram which connects the battery which concerns on embodiment of this invention, an inverter circuit, and an electric motor. It is a figure which shows the three-phase alternating current waveform of the drive current of the electric motor which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Vehicle, 10 Drive control apparatus (motor ECU), 12 Brake sensor, 14 Accelerator sensor, 16 Shift sensor, 18 Vehicle speed sensor, 20 Brake control apparatus (brake ECU), 30 Battery, 40 Electric motor (motor), 50 Inverter circuit, 50a to 50f Semiconductor switching element, 51 capacitor, 60 current detection device, 62 rotation angle sensor, 70 vehicle drive system, 72 transmission, 74 differential device, 80 drive wheel (tire), 90 brake device.

Claims (5)

In a vehicle drive control device that controls an inverter circuit in order to supply electric power necessary for an electric motor that drives a drive wheel of the vehicle,
Electrical angle detection means for detecting the electrical angle of the drive current of the electric motor;
Electrical angle predicting means for predicting an electrical angle when the vehicle is stopped by the detected electrical angle;
Comparison means for comparing the predicted electrical angle with the set electrical angle;
Stop control means for stopping the vehicle so that the predicted electrical angle is other than the set electrical angle;
A drive control device comprising: The drive control apparatus according to claim 1,
The stop control means stops the vehicle by brake torque;
A drive control device characterized by the above. In a vehicle drive control device that controls an inverter circuit in order to supply electric power necessary for an electric motor that drives a drive wheel of the vehicle,
Lock detecting means for detecting the locked state when the driving wheel falls into the locked state;
Electrical angle detection means for detecting the electrical angle of the drive current of the electric motor;
Comparison means for comparing the detected electrical angle with the set electrical angle, and electrical angle control for shifting the detected electrical angle by changing the driving force of the motor when the detected electrical angle matches the set electrical angle Means,
A drive control device comprising: The drive control apparatus according to claim 3.
The electrical angle control means reduces the driving force of the electric motor to shift the electrical angle,
A drive control device characterized by In the drive control device according to any one of claims 1 to 4,
The set electrical angle is that at least one phase is in the range of 90 ° ± 5 ° and 270 ° ± 5 °,
A drive control device characterized by the above.

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