JP6683052B2 - Converter device - Google Patents

Description

  The present invention relates to a converter device, and more particularly to a converter device including a buck-boost converter, a low voltage side capacitor, and a high voltage side capacitor.

  Conventionally, this type of converter device has two switching elements of an upper arm and a lower arm and a reactor, and is connected to a battery side (primary side) and an inverter side (secondary side) for driving a motor. A device including a boost converter, a filter capacitor that smoothes the output of the battery, and a smoothing capacitor that smoothes the output of the boost converter has been proposed (for example, see Patent Document 1). In this converter device, when discharging the charges of the smoothing capacitor and the filter capacitor, the duty of the boost converter is fixed and switching control of the upper arm and the lower arm is performed, so that the charges of the smoothing capacitor and the filter capacitor are discharged by the reactor. Have consumed.

International publication 2015/068533

  In the converter device described above, when discharging the charges of the smoothing capacitor and the filter capacitor, the duty of the boost converter is fixed, so that the temperature of the upper arm varies due to the variation in the heat generation amount of the upper arm and the heat generation amount of the lower arm. One of the lower arm temperature and the lower arm temperature may rise excessively.

  The converter device of the present invention mainly aims to suppress an excessive temperature rise of the upper arm and the lower arm of the buck-boost converter.

  The converter device of the present invention adopts the following means in order to achieve the above-mentioned main object.

The converter device of the present invention is
A buck-boost converter having two switching elements of an upper arm and a lower arm and a reactor, and exchanging power between the low-voltage side power line and the high-voltage side power line while changing the voltage.
A low-voltage side capacitor connected to the low-voltage side power line,
A high-voltage side capacitor connected to the high-voltage side power line,
A control device for controlling the buck-boost converter,
A converter device comprising:
The control device is
When the charges of the low-voltage side capacitor and the high-voltage side capacitor are consumed by the buck-boost converter and discharged,
When the temperature of the lower arm is higher than the temperature of the upper arm, the duty as the ratio of the ON time of the upper arm to the sum of the ON time of the upper arm and the ON time of the lower arm is increased,
When the temperature of the upper arm is higher than the temperature of the lower arm, the duty is reduced,
When the temperature of the upper arm is equal to the temperature of the lower arm, the duty is held.
That is the summary.

  In the converter device of the present invention, when the charge of the low-voltage side capacitor and the high-voltage side capacitor is consumed by the buck-boost converter and discharged, when the temperature of the lower arm is higher than the temperature of the upper arm, the upper arm is turned on. The duty is increased as the ratio of the upper arm on time to the sum of the time and the lower arm on time, and when the upper arm temperature is higher than the lower arm temperature, the duty is decreased to lower the upper arm temperature and lower arm temperature. When the arm temperature is equal, the duty is held. That is, when the temperature of the lower arm is higher than the temperature of the upper arm, the duty is increased to lengthen the ON time of the upper arm and shorten the ON time of the lower arm so that the temperature of the upper arm is lower than the temperature of the lower arm. When is also high, the duty is reduced to shorten the ON time of the upper arm and increase the ON time of the lower arm. As a result, it is possible to suppress an excessive temperature rise of the upper arm and the lower arm of the buck-boost converter. As a result, it is possible to further protect the two switching elements.

It is a block diagram which shows the outline of a structure of the electric vehicle 20 carrying the converter apparatus as one Example of this invention. It is a flow chart which shows an example of a buck-boost discharge control routine performed by electronic control unit 50 of an example.

  Next, modes for carrying out the present invention will be described using examples.

  FIG. 1 is a configuration diagram showing an outline of the configuration of an electric vehicle 20 equipped with a converter device as an embodiment of the present invention. As illustrated, the electric vehicle 20 of the embodiment includes a motor 32, an inverter 34, a battery 36, a boost converter 40, a high voltage side capacitor 46, a low voltage side capacitor 48, a system main relay SMR, And an electronic control unit 50. Here, in the embodiment, the boost converter 40, the high voltage side capacitor 46, the low voltage side capacitor 48, and the electronic control unit 50 correspond to a “converter device”.

  The motor 32 is configured as a synchronous generator motor, and includes a rotor in which permanent magnets are embedded, and a stator in which a three-phase coil is wound. The rotor of the motor 32 is connected to a drive shaft 26 connected to the drive wheels 22a and 22b via a differential gear 24.

  The inverter 34 is connected to the motor 32 and the high voltage side power line 42. The inverter 34 has six transistors T11 to T16 and six diodes D11 to D16. Each of the transistors T11 to T16 is arranged in pairs so as to be on the source side and the sink side with respect to the positive bus and the negative bus of the high voltage side power line 42. The six diodes D11 to D16 are respectively connected in parallel to the transistors T11 to T16 in opposite directions. Each of the three-phase coils (U-phase, V-phase, W-phase) of the motor 32 is connected to each of the connection points between the paired transistors of the transistors T11 to T16. Therefore, when a voltage is applied to the inverter 34, the electronic control unit 50 adjusts the on-time ratio of the pair of transistors T11 to T16, so that a rotating magnetic field is formed in the three-phase coil and the motor is 32 is rotationally driven. Hereinafter, the transistors T11 to T13 may be referred to as "upper arm", and the transistors T14 to T16 may be referred to as "lower arm".

  The battery 36 is configured as, for example, a lithium ion secondary battery or a nickel hydride secondary battery, and is connected to the low-voltage power line 44. The boost converter 40 is connected to the high voltage side power line 42 and the low voltage side power line 44. This boost converter 40 has two transistors T31 and T32, two diodes D31 and D32, and a reactor L. The transistor T31 is connected to the positive bus of the high voltage side power line 42. The transistor T32 is connected to the transistor T31 and the negative voltage bus lines of the high voltage side power line 42 and the low voltage side power line 44. The two diodes D31 and D32 are connected in parallel to the transistors T31 and T32 in opposite directions, respectively. The reactor L is connected to a connection point between the transistors T31 and T32 and a positive bus of the low voltage side power line 44. The boost converter 40 supplies the power of the low-voltage side power line 44 to the high-voltage side power line 42 by boosting the voltage by adjusting the ON time ratio of the transistors T31 and T32 by the electronic control unit 50. Alternatively, the power of the high-voltage side power line 42 is supplied to the low-voltage side power line 44 with a voltage drop.

  The high voltage side capacitor 46 is connected to the positive electrode bus bar and the negative electrode bus line of the high voltage side power line 42. The low voltage side capacitor 48 is attached to the positive electrode bus bar and the negative electrode bus line of the low voltage side power line 44. The system main relay SMR is provided closer to the battery 36 than the low voltage side capacitor 48 in the low voltage side power line 44. The system main relay SMR is ON / OFF controlled by the electronic control unit 50 to connect and disconnect the battery 36 to the boost converter 40 and the low voltage side capacitor 48.

  The electronic control unit 50 is configured as a microprocessor centered on a CPU 52, and includes a CPU 54, a ROM 54 for storing a processing program, a RAM 56 for temporarily storing data, and an input / output port.

  Signals from various sensors are input to the electronic control unit 50 via input ports. As the signal input to the electronic control unit 50, for example, the rotational position θm from a rotational position detection sensor (for example, a resolver) 32a that detects the rotational position of the rotor of the motor 32, and the current flowing in each phase of the motor 32 are detected. The phase currents Iu and Iv from the current sensors 32u and 32v that operate are listed. Moreover, the voltage VB from the voltage sensor 36a attached between the terminals of the battery 36, and the current IB from the current sensor 36b attached to the output terminal of the battery 36 can also be mentioned. Further, the voltage sensor mounted between the terminals of the high-voltage side capacitor 46, the voltage VH of the high-voltage side capacitor 46 (the high-voltage side power line 42) and the voltage sensor mounted between the terminals of the low-voltage side capacitor 48. The voltage VL of the low voltage side capacitor 48 (low voltage side power line 44) from 48a can also be mentioned. The upper arm temperature tup from the temperature sensor 40a attached to the transistor T31 (upper arm) of the step-up / down converter 40 and the lower arm temperature tdn from the temperature sensor 40b attached to the transistor T32 (lower arm) of the step-up / down converter 40 are also included. Can be mentioned. Ignition signal from ignition switch 60, shift position SP from shift position sensor 62 that detects the operating position of shift lever 61, accelerator opening Acc from accelerator pedal position sensor 64 that detects the amount of depression of accelerator pedal 63, and brake pedal The brake pedal position BP from the brake pedal position sensor 66 which detects the depression amount of 65 can also be mentioned. The vehicle speed VS from the vehicle speed sensor 68 and the vehicle body acceleration α from the acceleration sensor 69 can also be mentioned.

  Various control signals are output from the electronic control unit 50 via the output ports. Examples of signals output from the electronic control unit 50 include switching control signals to the transistors T11 to T16 of the inverter 34 and switching control signals to the transistors T31 and T32 of the boost converter 40.

  The electronic control unit 50 calculates the electrical angle θe, the angular velocity ωm, and the rotation speed Nm of the motor 32 based on the rotation position θm of the rotor of the motor 32 from the rotation position detection sensor 32a. Further, the electronic control unit 50 calculates the charge ratio SOC of the battery 36 based on the integrated value of the current IB of the battery 36 from the current sensor 36b. Here, the charge ratio SOC is the ratio of the capacity of the electric power that can be discharged from the battery 36 to the total capacity of the battery 36.

  In the thus configured electric vehicle 20 of the embodiment, the electronic control unit 50 performs the following traveling control. In the traveling control, the required torque Td * required for the drive shaft 26 is set based on the accelerator opening Acc and the vehicle speed VS, and the set required torque Td * is set as the torque command Tm * of the motor 32. Performs switching control of the transistors T11 to T16 of the inverter 34 so that is driven by the torque command Tm *. Further, the target voltage VH * of the high voltage side power line 42 is set so that the motor 32 can be driven by the torque command Tm *, and the boost converter 40 is set so that the voltage VH of the high voltage side power line 42 becomes the target voltage VH *. The switching control of the transistors T31 and T32 is performed.

  Further, in the electric vehicle 20 of the embodiment, when the collision of the vehicle is detected, the voltage VH of the high-voltage side capacitor 46 (and the voltage VL of the low-voltage side capacitor 48) is set to the threshold value VHref after the system main relay SMR is turned off. Buck-boost discharge control that controls the buck-boost converter 40 so that the charges of the high-voltage side capacitor 46 and the low-voltage side capacitor 48 are consumed by the buck-boost converter 40 up to (for example, 50 V, 60 V, 70 V, etc.) To execute. Here, it is assumed that the vehicle collision is detected when the vehicle body acceleration α detected by the acceleration sensor 69 exceeds a collision determination threshold value αref. When the transistor T31 is turned off and the transistor T32 is turned on by executing this step-up / down discharge control, the charge of the low-voltage side capacitor 48 is consumed as a loss in the reactor L and the transistor T32, and the transistor T31 is turned on. At the same time, when the transistor T32 is turned off, the electric charge of the high-voltage side capacitor 46 is consumed as a loss in the transistor T31 and the reactor L. In this way, the high-voltage side capacitor 46 and the low-voltage side capacitor 48 can be discharged.

  Next, the operation of the electric vehicle 20 of the embodiment thus configured, particularly the operation when executing the buck-boost discharge control will be described. FIG. 2 is a flowchart showing an example of the step-up / down discharge control routine executed by the electronic control unit 50 of the embodiment. This routine is performed every predetermined time (for example, tens of msec or hundreds of msec) until the voltage VH of the high-voltage side capacitor 46 reaches the threshold VHref or less after detecting the collision of the vehicle and turning off the system main relay SMR. It is executed repeatedly.

  When the buck-boost discharge control routine is executed, the electronic control unit 50 first determines whether or not it is immediately after turning off the system main relay SMR (step S100). When it is determined that the system main relay SMR has just been turned off, the target duty D * is set to the predetermined value Dst (step S110), and the transistor of the buck-boost converter 40 is set using the set target duty D *. Switching control of T31 and T32 is performed (step S180), and this routine is ended. Here, the target duty D * is a target value of the duty D as a ratio of the on time of the transistor T31 (upper arm) to the sum of the on time of the transistor T31 (upper arm) and the on time of the transistor T32 (lower arm). Is. The predetermined value Dst may be 50%, for example, as a value at which the energy efficiency of the step-up / down converter 40 is relatively low (the loss of the reactor L is relatively large).

  When it is determined in step S100 that it is not immediately after the system main relay SMR is turned off, the upper arm temperature tup from the temperature sensor 40a and the lower arm temperature tdn from the temperature sensor 40b are input (step S120), and the upper arm temperature tup is input. And the lower arm temperature tdn are compared (steps S130 and S140).

  When the lower arm temperature tdn is higher than the upper arm temperature tup, a new target duty D * is set by adding a predetermined value ΔDup to the target duty (previous D *) set when the routine was last executed. (Step S150), the switching control of the transistors T31 and T32 of the step-up / down converter 40 is performed using the set target duty D * (step S180), and this routine is ended. Here, the predetermined value ΔDup is an increase amount of the target duty D * per execution interval of this routine, and for example, 1%, 2%, 3% per 100 msec can be used.

  When the upper arm temperature tup is higher than the lower arm temperature tdn, a value obtained by subtracting the predetermined value ΔDdn from the target duty (previous D *) set when this routine was executed last time is set as a new target duty D *. (Step S160), switching control of the transistors T31 and T32 of the step-up / down converter 40 is performed using the set target duty D * (step S180), and this routine is ended. Here, the predetermined value ΔDup is a reduction amount of the target duty D * per execution interval of this routine, and for example, 1%, 2%, 3% per 100 msec can be used.

  When the upper arm temperature tup and the lower arm temperature tdn are equal, the target duty (previous D *) set when the routine was last executed is set as a new target duty D *, that is, the target duty D * is held. (Step S170), switching control of the transistors T31 and T32 of the step-up / down converter 40 is performed using the set target duty D * (step S180), and this routine ends.

  In this way, by changing the target duty D * according to the magnitude relation between the upper arm tup and the lower arm temperature tdn, the following effects can be obtained. Here, as a comparative example, it is assumed that the target duty D * is fixed at a predetermined value Dst. Basically, the upper arm temperature tup becomes higher as the ON time of the transistor T31 is longer (duty D is larger), and the lower arm temperature tdn becomes higher as the ON time of the transistor T32 is longer (duty D is smaller). When the target duty D * is fixed to the predetermined value Dst, the upper arm temperature tup and the lower arm temperature tup are decreased due to the variation in the heat generation amount of the transistor T31 (upper arm) and the heat generation amount of the transistor T32 (lower arm) during execution of the buck-boost discharge control. One of the arm temperatures tdn may rise excessively. On the other hand, in the embodiment, when the lower arm temperature tdn is higher than the upper arm temperature tup, the target duty D * is increased to lengthen the on time of the transistor T31 and shorten the on time of the transistor T32. Thus, the temperature rise of the transistor T32 can be suppressed. Further, in the embodiment, when the upper arm temperature tup is higher than the lower arm temperature tdn, the target duty D * is reduced to shorten the on time of the transistor T31 and increase the on time of the transistor T32. The temperature rise of T31 can be suppressed. As a result, it is possible to prevent the upper arm temperature tup and the lower arm temperature tdn from rising excessively, and it is possible to further protect the transistors T31 and T32.

  In the converter device mounted on the electric vehicle 20 of the embodiment described above, when the buck-boost discharge control is executed, when the lower arm temperature tdn is higher than the upper arm temperature tup, the target duty D * is increased, The on-time of the transistor T31 is lengthened and the on-time of the transistor T32 is shortened. On the other hand, when the upper arm temperature tup is higher than the lower arm temperature tdn, the target duty D * is reduced to shorten the on time of the transistor T31 and lengthen the on time of the transistor T32. As a result, it is possible to suppress an excessive rise in the upper arm temperature tup and the lower arm temperature tdn, and it is possible to further protect the transistors T31 and T32.

  In the converter device equipped with the electric vehicle 20 of the embodiment, the upper arm temperature tup is detected by the temperature sensor 40a, but may be estimated based on the loss Lup of the transistor T31 (upper arm). Here, the loss Lup of the transistor T31 is the loss Lupsw due to the switching of the transistor T31, the loss Lupon when the transistor T31 is on, the carrier frequency fc used for controlling the step-up / down converter 40, and the high voltage system power line 42. Can be obtained by the equation (1) by using the voltage VH of the above and the voltage VL of the low voltage system power line 44. Further, in the embodiment, the lower arm temperature tdn is detected by the temperature sensor 40b, but it may be estimated based on the loss Ldn of the transistor T32 (lower arm). Here, the loss Ldn of the transistor T32 is the loss Ldnsw due to the switching of the transistor T32, the loss Ldnon when the transistor T32 is on, the carrier frequency fc used for controlling the step-up / down converter 40, and the high voltage system power line 42. Of the low voltage system power line 44 and the voltage VL of the low voltage system power line 44, and can be obtained by the equation (2).

Lup = (Lupsw ・ fc ・ VH) + (Lupon ・ VL / VH) (1)
Ldn = (Ldnsw ・ fc ・ VH) + (Ldnon ・ (1-VL / VH)) (2)

  In the converter device mounted on the electric vehicle 20 of the embodiment, the buck-boost discharge control is executed after detecting the collision of the vehicle and turning off the system main relay SMR, but at other times, for example, When the rotation position detection sensor 32a becomes abnormal and the d-axis current cannot flow through the motor 32 to stop the electric charge of the high-voltage side capacitor 46 and the low-voltage side capacitor 48 after the vehicle is stopped, or the ignition is turned off. The boosting / boosting discharge control may be executed even when the power is off.

  In the embodiment, the configuration of the converter device mounted on the electric vehicle 20 is adopted. However, since the converter device may be configured to include the buck-boost converter, the high-voltage side capacitor, and the low-voltage side capacitor, the configuration of the converter device mounted on a vehicle other than an electric vehicle, for example, a hybrid vehicle or a fuel cell vehicle. Alternatively, the converter device may be installed in equipment that does not move, such as construction equipment.

  Correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem will be described. In the embodiment, the buck-boost converter 40 corresponds to a "buck-boost converter", the low-voltage side capacitor 48 corresponds to a "low-voltage side capacitor", the high-voltage side capacitor 46 corresponds to a "high-voltage side capacitor", The electronic control unit 50 that executes the buck-boost discharge control routine of FIG. 2 corresponds to a “control device”.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem is the same as that of the embodiment described in the section of means for solving the problem. Since this is an example for specifically explaining the mode for carrying out the invention, it does not limit the elements of the invention described in the column of means for solving the problem. That is, the interpretation of the invention described in the column of means for solving the problem should be made based on the description in that column, and the embodiment is the invention of the invention described in the column of means for solving the problem. This is just a specific example.

  Although the embodiments for carrying out the present invention have been described above with reference to the embodiments, the present invention is not limited to these embodiments, and various embodiments are possible within the scope not departing from the gist of the present invention. Of course, it can be implemented.

  INDUSTRIAL APPLICABILITY The present invention can be used in the converter device manufacturing industry and the like.

  20 electric vehicle, 22a, 22b drive wheel, 24 differential gear, 26 drive shaft, 32 motor, 32a rotational position detection sensor, 32u, 32v, 36b current sensor, 34 inverter, 36 battery, 36a, 46a, 48a voltage sensor, 40 Boost converter, 40a, 40b Temperature sensor, 42 High voltage side power line, 44 Low voltage side power line, 46 High voltage side capacitor, 48 Low voltage side capacitor, 50 Electronic control unit, 52 CPU, 54 ROM, 56 RAM, 60 Ignition switch, 61 shift lever, 62 shift position sensor, 63 accelerator pedal, 64 accelerator pedal position sensor, 65 brake pedal, 66 brake pedal position sensor, 68 vehicle speed sensor, 69 acceleration sensor D11 to D16, D31, D32 Diode, L reactor, SMR system main relay, T11 to T16, T31, T32 Transistor.

Claims (1)

A buck-boost converter having two switching elements of an upper arm and a lower arm and a reactor, and exchanging power between the low-voltage side power line and the high-voltage side power line while changing the voltage.
A low-voltage side capacitor connected to the low-voltage side power line,
A high-voltage side capacitor connected to the high-voltage side power line,
A control device for controlling the buck-boost converter,
A converter device comprising:
The control device is
When the charges of the low-voltage side capacitor and the high-voltage side capacitor are consumed by the buck-boost converter and discharged,
When the temperature of the lower arm is higher than the temperature of the upper arm, the duty as the ratio of the ON time of the upper arm to the sum of the ON time of the upper arm and the ON time of the lower arm is increased,
When the temperature of the upper arm is higher than the temperature of the lower arm, the duty is reduced,
When the temperature of the upper arm is equal to the temperature of the lower arm, the duty is held.
Converter device.

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