JP2018019451A - Converter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an excessive temperature rise of upper and lower arms of a step-up/step-down converter.SOLUTION: When electric charges of a low-voltage side capacitor and a high-voltage side capacitor are consumed and discharged by a step-up/step-down converter, in a case where a temperature of a lower arm is higher than that of an upper arm, a duty as a proportion of an ON time period of the upper arm to a sum of the ON time period of the upper arm and an ON time period of the lower arm, is increased. In a case where the temperature of the upper arm is higher than that of the lower arm, the duty is decreased. In a case where the temperature of the upper arm and that of the lower arm are equal to each other, the duty is maintained.SELECTED DRAWING: Figure 2

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 (see, for example, 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 the 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 changed by the reactor. It is consumed.

International Publication No. 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 depending on the amount of heat generated by the upper arm and the amount of heat generated by the lower arm. And one of the temperature of the lower arm may rise excessively.

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

  The converter device of the present invention employs the following means in order to achieve the main object described above.

The converter device of the present invention is
A step-up / down converter having two switching elements and a reactor of an upper arm and a lower arm, and exchanging power between the low voltage side power line and the high voltage side power line with a change in 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 controller is
When the electric 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, increase the duty as a 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,
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 and the temperature of the lower arm are equal, the duty is maintained.
This is the gist.

  In the converter device according to 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, the upper arm is turned on when the temperature of the lower arm is higher than the temperature of the upper arm. Increase the duty as a 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, decrease the duty and lower the upper arm temperature and lower arm temperature. When the temperature of the arm is equal, the duty is maintained. That is, when the temperature of the lower arm is higher than the temperature of the upper arm, the duty is increased to increase the on-time of the upper arm and shorten the on-time of the lower arm. If it is higher, the duty is reduced to shorten the on-time of the upper arm and lengthen the on-time of the lower arm. Thereby, the excessive temperature rise of the upper arm and lower arm of a buck-boost converter can be suppressed. As a result, the two switching elements can be further protected.

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 flowchart which shows an example of the buck-boost discharge control routine performed by the electronic control unit 50 of an Example.

  Next, the form for implementing this invention is demonstrated using an Example.

  FIG. 1 is a configuration diagram showing an outline of a 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 a permanent magnet is embedded and a stator around which a three-phase coil is wound. The rotor of the motor 32 is connected to a drive shaft 26 that is coupled to the drive wheels 22a and 22b via a differential gear 24.

  The inverter 34 is connected to the motor 32 and to the high voltage side power line 42. The inverter 34 includes six transistors T11 to T16 and six diodes D11 to D16. Two transistors T11 to T16 are arranged in pairs so as to be on the source side and the sink side with respect to the positive electrode bus and the negative electrode bus of the high voltage side power line 42, respectively. The six diodes D11 to D16 are respectively connected in parallel to the transistors T11 to T16 in the reverse direction. Each of the three-phase coils (U-phase, V-phase, W-phase) of the motor 32 is connected to each connection point between the transistors T11 to T16 as a pair. Therefore, when a voltage is applied to the inverter 34, the electronic control unit 50 adjusts the ratio of the on-time of the paired transistors T11 to T16, so that a rotating magnetic field is formed in the three-phase coil, and the motor 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, for example, as a lithium ion secondary battery or a nickel hydride secondary battery, and is connected to the low voltage side power line 44. Boost converter 40 is connected to high voltage side power line 42 and low voltage side power line 44. Boost converter 40 includes 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 buses of the high voltage side power line 42 and the low voltage side power line 44. The two diodes D31 and D32 are respectively connected in parallel to the transistors T31 and T32 in the reverse direction. 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 step-up converter 40 supplies the power of the low-voltage side power line 44 to the high-voltage side power line 42 with voltage boost by adjusting the on-time ratio of the transistors T31 and T32 by the electronic control unit 50. Or the power of the high-voltage side power line 42 is supplied to the low-voltage side power line 44 with voltage step-down.

  The high voltage side capacitor 46 is connected to the positive electrode bus and the negative electrode bus of the high voltage side power line 42. The low voltage side capacitor 48 is attached to the positive electrode bus and the negative electrode bus 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. This system main relay SMR is on / off controlled by the electronic control unit 50 to connect and disconnect the battery 36 from the boost converter 40 and the low voltage side capacitor 48.

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

  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 the rotational position detection sensor (for example, resolver) 32a that detects the rotational position of the rotor of the motor 32, and the current flowing through each phase of the motor 32 are detected. The phase currents Iu and Iv from the current sensors 32u and 32v to be used can be mentioned. Further, 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 VH of the high voltage side capacitor 46 (high voltage side power line 42) from the voltage sensor 46a attached between the terminals of the high voltage side capacitor 46, and the voltage sensor attached 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 buck-boost converter 40, and the lower arm temperature tdn from the temperature sensor 40b attached to the transistor T32 (lower arm) of the buck-boost converter 40 are also used. Can be mentioned. The ignition signal from the ignition switch 60, the shift position SP from the shift position sensor 62 that detects the operation position of the shift lever 61, the accelerator opening Acc from the accelerator pedal position sensor 64 that detects the depression amount of the accelerator pedal 63, the brake pedal The brake pedal position BP from the brake pedal position sensor 66 that 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 through an output port. Examples of the signal output from the electronic control unit 50 include a switching control signal to the transistors T11 to T16 of the inverter 34 and a switching control signal 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 rotational speed Nm of the motor 32 based on the rotational position θm of the rotor of the motor 32 from the rotational position detection sensor 32a. Further, the electronic control unit 50 calculates the storage 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 storage ratio SOC is the ratio of the capacity of power that can be discharged from the battery 36 to the total capacity of the battery 36.

  In the electric vehicle 20 of the embodiment thus configured, the electronic control unit 50 performs the following traveling control. In the travel control, the required torque Td * required for the drive shaft 26 is set based on the accelerator opening Acc and the vehicle speed VS, the set required torque Td * is set as the torque command Tm * of the motor 32, and the motor 32 Is controlled by the torque command Tm * to perform switching control of the transistors T11 to T16 of the inverter 34. 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 transistors T31 and T32 are controlled to be switched.

  In the electric vehicle 20 of the embodiment, when a vehicle collision is detected, the system main relay SMR is turned off and then 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. Step-up / step-down discharge control for controlling the step-up / step-down converter 40 so that the charges of the high-voltage side capacitor 46 and the low-voltage side capacitor 48 are consumed by the step-up / step-down converter 40 up to (for example, 50V, 60V, 70V). Execute. Here, the vehicle collision is detected when the vehicle body acceleration α detected by the acceleration sensor 69 exceeds the threshold value αref for collision determination. When the transistor T31 is turned off and the transistor T32 is turned on by executing this step-up / step-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 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 configured as described above, particularly the operation when executing the step-up / step-down discharge control will be described. FIG. 2 is a flowchart illustrating an example of the step-up / step-down discharge control routine executed by the electronic control unit 50 according to the embodiment. This routine detects a vehicle collision and turns off the system main relay SMR until the voltage VH of the high voltage side capacitor 46 reaches a threshold value VHref or less every predetermined time (for example, several tens of milliseconds or several hundreds of milliseconds). Repeatedly executed.

  When the step-up / step-down discharge control routine is executed, the electronic control unit 50 first determines whether or not it is immediately after the system main relay SMR is turned off (step S100). When it is determined that it is immediately after the system main relay SMR is turned off, a predetermined value Dst is set to the target duty D * (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 finished. 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). It is. As the predetermined value Dst, for example, 50% or the like can be used as a value at which the energy efficiency of the buck-boost converter 40 becomes relatively low (the loss of the reactor L becomes relatively large).

  If it is determined in step S100 that the system main relay SMR is not immediately 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 value obtained by adding a predetermined value ΔDup to the target duty (previous D *) set when the routine was executed last time is set as a new target duty D *. (Step S150), the switching control of the transistors T31 and T32 of the buck-boost converter 40 is performed using the set target duty D * (Step S180), and this routine is finished. 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%, etc. can be used per 100 msec.

  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 the 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 buck-boost converter 40 is performed using the set target duty D * (Step S180), and this routine is terminated. 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%, etc. can be used per 100 msec.

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

  As described above, by changing the target duty D * according to the magnitude relationship 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 is higher as the ON time of the transistor T32 is longer (duty D is smaller). When the target duty D * is fixed at the predetermined value Dst, the upper arm temperature tup and the lower temperature are reduced due to variations in the heat generation amount of the transistor T31 (upper arm) and the heat generation amount of the transistor T32 (lower arm) when the buck-boost discharge control is executed. One of the arm temperatures tdn may increase excessively. In contrast, in the embodiment, when the lower arm temperature tdn is higher than the upper arm temperature tup, the target duty D * is increased to increase 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. In the embodiment, when the upper arm temperature tup is higher than the lower arm temperature tdn, the target duty D * is decreased to shorten the on-time of the transistor T31 and lengthen the on-time of the transistor T32. The temperature rise of T31 can be suppressed. As a result, excessive increases in the upper arm temperature tup and the lower arm temperature tdn can be suppressed, and the transistors T31 and T32 can be further protected.

  In the converter device mounted on the electric vehicle 20 of the embodiment described above, when the step-up / step-down 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 decreased to shorten the on-time of the transistor T31 and lengthen the on-time of the transistor T32. Accordingly, excessive increases in the upper arm temperature tup and the lower arm temperature tdn can be suppressed, and the transistors T31 and T32 can be further protected.

  In the converter device on which the electric vehicle 20 of the embodiment is mounted, 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 includes the loss Lupsw associated with the switching of the transistor T31, the loss Lpon when the transistor T31 is turned on, the carrier frequency fc used for controlling the buck-boost converter 40, and the high voltage system power line 42. The voltage VH and the voltage VL of the low voltage system power line 44 can be obtained by the equation (1). In the embodiment, the lower arm temperature tdn is detected by the temperature sensor 40b, but may be estimated based on the loss Ldn of the transistor T32 (lower arm). Here, the loss Ldn of the transistor T32 includes the loss Ldnsw associated with the switching of the transistor T32, the loss Ldnon when the transistor T32 is on, the carrier frequency fc used to control the buck-boost converter 40, and the high voltage system power line 42. The voltage VH and the voltage VL of the low voltage system power line 44 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 step-up / step-down discharge control is executed after detecting the collision of the vehicle and turning off the system main relay SMR. When the rotation position detection sensor 32a becomes abnormal, for example, when the d-axis current cannot be supplied to the motor 32 after the vehicle stops to discharge the high-voltage side capacitor 46 or the low-voltage side capacitor 48, or the ignition is turned off. Also, the step-up / step-down discharge control may be executed.

  In the embodiment, the converter device is mounted on the electric vehicle 20. However, since the configuration of the converter device provided with the step-up / step-down converter, the high-voltage side capacitor, and the low-voltage side capacitor is sufficient, the configuration of the converter device mounted on a vehicle other than an electric vehicle, such as a hybrid vehicle or a fuel cell vehicle Alternatively, it may be a configuration of a converter device mounted on a non-moving facility such as a construction facility.

  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 problems 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 step-up / step-down 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 column of means for solving the problem. Therefore, the elements of the invention described in the column of means for solving the problems are not limited. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description of the column, and the examples are those of the invention described in the column of means for solving the problems. It is only a specific example.

  As mentioned above, although the form for implementing this invention was demonstrated using the Example, this invention is not limited at all to such an Example, In the range which does not deviate from the summary of this invention, it is with various forms. Of course, it can be implemented.

  The present invention is applicable to 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 D, D11 to D16, D31, D32 Diode, L reactor, SMR system main relay, T11 to T16, T31, T32 transistors.

Claims (1)

A step-up / down converter having two switching elements and a reactor of an upper arm and a lower arm, and exchanging power between the low voltage side power line and the high voltage side power line with a change in 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 controller is
When the electric 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, increase the duty as a 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,
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 and the temperature of the lower arm are equal, the duty is maintained.
Converter device.

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