JP6935739B2 - Boost system - Google Patents

Description

The present invention relates to a boosting system.

Conventionally, this type of boosting system has first and second switching elements as upper and lower arms, first and second diodes, and a reactor, and is accompanied by voltage conversion between the battery side and the motor side. In a booster system equipped with a DC / DC converter that exchanges power, one-arm drive that drives only one of the first and second switching elements on and off and both the first and second switching elements are reversed from each other. It has been proposed to switch between double-arm drive, which drives on and off in a phase, and to execute the drive (see, for example, Patent Document 1). In this boosting system, the current value flowing through the reactor is sampled at a timing determined by the carrier signal, and single-arm drive or double-arm drive is switched based on the sampled current value.

Japanese Unexamined Patent Publication No. 2014-147206

In such a boosting system, when switching from single-arm drive (single-element control) to double-arm drive (double-element control), the timing of turning off one switching element (for example, the lower arm) that is driven on and off by single-arm drive If the interval between the timing of turning on the other switching element (for example, the upper arm) is short in driving both arms, the positive electrode side line and the negative electrode side line of the power line on the motor side (electrical load side) may be short-circuited. There is sex.

The main purpose of the boosting system of the present invention is to prevent a short circuit between the positive electrode side line and the negative electrode side line of the power line on the electric load side when switching from single element control to double element control.

The booster system of the present invention has adopted the following means in order to achieve the above-mentioned main object.

The booster system of the present invention
A buck-boost that has first and second switching elements as upper and lower arms, first and second diodes, and a reactor, and exchanges power with voltage conversion between the power supply side and the electric load side. With a converter
As the control of the buck-boost converter based on the comparison result between the duty command and the step-up carrier, one-element control that switches only one of the first and second switching elements or the first and second switching elements. A control device that executes both element control that switches both elements,
It is a booster system equipped with
When switching from the one-element control to the two-element control, the control device switches from the one-element control to the two-element control at the timing of the minimum value of the boost carrier when the duty command is equal to or higher than the threshold value. When the duty command is less than the threshold value, the single element control is switched to the double element control at the timing of the maximum value of the boost carrier.
The gist is that.

In the booster system of the present invention, one-element control that switches only one of the first and second switching elements or one-element control that switches only one of the first and second switching elements as the control of the buck-boost converter based on the comparison result between the duty command and the boost carrier. Both element control for switching both the first and second switching elements is executed. Here, the duty command is the ratio of the on-time to the sum of the on-time and the off-time of the first switching element (the on-time and the off-time of the second switching element) when the dead time is not taken into consideration in both element control. In the control that switches only the first switching element in the one-element control, it corresponds to the ratio of the on-time to the sum of the on-time and the off-time of the first switching element. In the element control in which only the second switching element is switched, it corresponds to the ratio of the off time to the sum of the on time and the off time of the second switching element. Further, in the dual element control, a dead time is provided in order to avoid the simultaneous on of the upper and lower arms, and in the single element control, the dead time is not provided because the upper and lower arms are not turned on at the same time. When switching from single-element control to double-element control, when the duty command is equal to or greater than the threshold value, the single-element control is switched to double-element control at the timing of the minimum value (valley) of the boost carrier, and when the duty command is less than the threshold value. , Switch from single element control to double element control at the timing of the maximum value (mountain) of the boost carrier. By such control, when switching from one-element control to two-element control, the timing of turning off one switching element (for example, the lower arm) that is switched by one-element control and the other switching element (for example, for example) by both-element control. It is possible to prevent the interval between the timing of turning on the upper arm) and the interval from becoming too short, and to prevent the positive electrode side line and the negative electrode side line of the electric load side power line from being short-circuited.

It is a block diagram which shows the outline of the structure of the electric vehicle 20 which mounts the boosting system as one Example of this invention. It is explanatory drawing which shows an example of the state of the upper and lower arms in duty command D *, a step-up carrier, a switching command, both element control, and lower single element control. It is explanatory drawing which shows an example of the state of the upper and lower arms in duty command D *, a step-up carrier, a switching command, both element control, and upper single element control. It is a flowchart which shows an example of the control switching routine executed by an electronic control unit 50. It is explanatory drawing which shows an example of the state of switching from the lower single element control to the double element control when the duty command D * is less than the threshold value Dreff. It is explanatory drawing which shows an example of the state of switching from the upper single element control to the double element control when the duty command D * is equal to or more than a threshold value Dreff.

Next, a mode for carrying out the present invention will be described with reference to examples.

FIG. 1 is a configuration diagram showing an outline of a configuration of an electric vehicle 20 equipped with a boosting system as an embodiment of the present invention. As shown in the figure, the electric vehicle 20 of the embodiment includes a motor 32, an inverter 34, a battery 36 as a power source, a buck-boost converter 40, and an electronic control unit 50. The "boost-boosting system" of the embodiment mainly corresponds to the buck-boost converter 40 and the electronic control unit 50.

The motor 32 is configured as a synchronous generator motor, and includes a rotor in which a permanent magnet is 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 used to drive the motor 32. The inverter 34 is connected to the buck-boost converter 40 via a high-voltage side power line 42, and is connected in parallel to each of the transistors T11 to T16 as six switching elements and the six transistors T11 to T16. It has 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 side line and the negative electrode side line of the high voltage side power line 42, respectively. Further, each of the three-phase coils (U-phase, V-phase, and W-phase coils) of the motor 32 is connected to each of the connection points between the transistors paired with the transistors T11 to T16. 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. A smoothing capacitor 46 is attached to the positive electrode side line and the negative electrode side line of the high voltage side power line 42.

The battery 36 is configured as, for example, a lithium ion secondary battery or a nickel hydrogen secondary battery, and is connected to the buck-boost converter 40 via a low voltage side power line 44. A smoothing capacitor 48 is attached to the positive electrode side line and the negative electrode side line of the low voltage side power line 44.

The buck-boost converter 40 is connected to the high-voltage side power line 42 and the low-voltage side power line 44, and is connected in parallel to the two transistors T31 and T32 and the two transistors T31 and T32, respectively. It has diodes D31 and D32 and a reactor L. The transistor T31 is connected to the positive electrode side line of the high voltage side power line 42. The transistor T32 is connected to the transistor T31 and the negative electrode side line of the high voltage side power line 42 and the low voltage side power line 44. The reactor L is connected to a connection point between the transistors T31 and T32 and a positive electrode side line of the low voltage side power line 44. The buck-boost converter 40 boosts the power of the low-voltage side power line 44 and supplies it to the high-voltage side power line 42 by adjusting the ratio of the on-time of the transistors T31 and T32 by the electronic control unit 50. , The power of the high voltage side power line 42 is stepped down and supplied to the low voltage side power line 44. Hereinafter, the transistors T31 and T32 may be referred to as an "upper arm" and a "lower arm", respectively.

The electronic control unit 50 is configured as a microprocessor centered on a 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 rotation position θm from the rotation position detection sensor (for example, resolver) 32a that detects the rotation position of the rotor of the motor 32, and the phase current of each phase of the motor 32 are used. The phase currents Iu and Iv from the current sensors 32u and 32v to be detected 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 current IL from the current sensor 40a attached in series with the reactor L, the voltage VH of the capacitor 46 (high voltage side power line 42) from the voltage sensor 46a attached between the terminals of the capacitor 46, and the capacitor 48. The voltage VL of the capacitor 48 (low voltage side power line 44) from the voltage sensor 48a attached between the terminals can also be mentioned. In addition, the ignition signal from the ignition switch 60 and the shift position SP from the shift position sensor 62 that detects the operation position of the shift lever 61 can also be mentioned. Further, the accelerator opening Acc from the accelerator pedal position sensor 64 that detects the depression amount of the accelerator pedal 63, the brake pedal position BP from the brake pedal position sensor 66 that detects the depression amount of the brake pedal 65, and the vehicle speed sensor 68. The vehicle speed V can also be mentioned.

Various control signals are output from the electronic control unit 50 via the output port. Examples of the signal output from the electronic control unit 50 include a switching control signal for the transistors T11 to T16 of the inverter 34 and a switching control signal for the transistors T31 and T32 of the buck-boost converter 40. The electronic control unit 50 calculates the electric angle θe 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 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 storage amount (dischargeable power amount) of the battery 36 to the total capacity of the battery 36.

In the electric vehicle 20 of the embodiment configured in this way, the electronic control unit 50 sets the required torque Td * required for the drive shaft 26 based on the accelerator opening degree Acc and the vehicle speed V, and sets the required torque Td *. Is set to the torque command Tm * of the motor 32, and switching control of the transistors T11 to T16 of the inverter 34 is performed so that the motor 32 is driven by the torque command Tm *. Further, the electronic control unit 50 sets the target voltage VH * of the high voltage side power line 42 so that the motor 32 can be driven by the torque command Tm *, and sets the voltage VH and the target voltage VH * of the high voltage side power line 42. The duty command D * is set so that the difference between the two elements is canceled, and based on the comparison result between the set duty command D * and the boost carrier, the buck-boost converter 40 is controlled by both element control or one element control (upper piece). Element control or lower single element control) is executed.

Here, the dual element control is a control for switching both the upper and lower arms (transistors T31 and T32), and the single element control is a control for switching only one of the upper and lower arms. The upper single element control is a control that switches only the upper arm of the upper and lower arms, and the lower single element control is a control that switches only the lower arm of the upper and lower arms.

Further, the duty command D * is the ratio of the on-time to the sum of the on-time and the off-time of the upper arm (transistor T31) when the dead time is not taken into consideration in the control of both elements (the on-time of the lower arm (transistor T32)). The duty command D * corresponds to the ratio of the off time to the sum of the on time and the off time of the upper arm, and the duty command D * corresponds to the ratio of the on time to the sum of the on time and the off time of the upper arm in the upper single element control. In one-element control, it corresponds to the ratio of the off time to the sum of the on time and the off time of the lower arm. Further, in both element control, a dead time DT is provided in order to avoid simultaneous on of the upper and lower arms (short circuit between the positive electrode side line and the negative electrode side line of the high voltage side power line 42), and the upper single element control and the lower side are provided. In the single element control, since the upper and lower arms are not turned on at the same time, the dead time DT is not provided.

Further, in the embodiment, when the absolute value of the current IL of the reactor L of the buck-boost converter 40 is equal to or less than the threshold ILref, both element control is executed, and the absolute value of the current IL of the reactor L is larger than the threshold ILref and the reactor L When the current IL of is positive, the lower one-element control that switches only the transistor T32 in the one-element control is executed, the absolute value of the current IL of the reactor L is larger than the threshold ILref, and the current IL of the reactor L is negative. At this time, the upper single-element control that switches only the transistor T31 among the single-element controls is executed.

FIG. 2 is an explanatory diagram showing an example of the state of the upper and lower arms (transistors T31 and T32) in the duty command D *, the boost carrier, the switching command, the control of both elements and the control of the lower single element. FIG. 3 is an explanatory diagram showing an example of the state of the upper and lower arms in the duty command D *, the boost carrier, the switching command, the control of both elements, and the control of the upper single element. The switching command of FIGS. 2 and 3 is a command that turns on when the duty command D * is equal to or higher than the boost carrier and turns off when the duty command D * is less than the boost carrier. (See FIG. 3) is the same as this switching command. As described above and as shown in FIGS. 2 and 3, a dead time DT is provided in both element control, and a dead time DT is not provided in the upper single element control and the lower single element control.

Next, the operation of the boosting system mounted on the electric vehicle 20 of the embodiment configured in this manner, particularly the operation when switching from single-element control (upper single-element control or lower single-element control) to double-element control will be described. do. FIG. 4 is a flowchart showing an example of a control switching routine executed by the electronic control unit 50. This routine is executed when a request for switching from single-element control to double-element control is made (when the absolute value of the current IL of the reactor L becomes equal to or less than the threshold value ILref).

When the control switching routine of FIG. 4 is executed, the electronic control unit 50 inputs the duty command D * (step S100) and compares the input duty command D * with the threshold value Dref (step S110). Here, as the threshold value Dr, a value near 0.5, for example, 0.4, 0.5, 0.6, or the like is used.

When the duty command D * is equal to or higher than the threshold value Dref, the timing of the step-up carrier valley (minimum value) is set in the switching timing (step S120), and when the duty command D * is less than the threshold value Dref, the step-up carrier peak is set in the switching timing. The timing of (maximum value) is set (step S130). Then, when the switching timing is reached, the single element control is switched to the double element control (step S140), and this routine is terminated.

FIG. 5 is an explanatory diagram showing an example of a state in which the lower single element control is switched to the double element control when the duty command D * is less than the threshold value Dreff. In the modified example, as shown in the middle part of FIG. 5, the lower arm is turned off and the upper arm is turned on by switching from the lower single element control to the double element control at the timing of the valley (minimum value) of the boost carrier. The interval ΔT with the timing of setting is shorter than the above-mentioned dead time DT. If this interval is shortened, the positive electrode side line and the negative electrode side line of the high voltage side power line 42 may be short-circuited. On the other hand, in the embodiment, as shown in the lower part of FIG. 5, the timing of turning off the lower arm by switching from the lower single element control to the double element control at the timing of the peak (maximum value) of the boost carrier. And the timing of turning on the upper arm can be shifted by the dead time DT, and it is possible to suppress a short circuit between the positive electrode side line and the negative electrode side line of the high voltage side power line 42. When switching from the upper single element control to the double element control when the duty command D * is less than the threshold Dref, if the switch is made at the valley of the boost carrier, the upper arm will continue to be turned on before and after the switch, which is high. Since the possibility that the positive electrode side line and the negative electrode side line of the voltage side power line 42 are short-circuited is sufficiently low, it is considered that switching may be performed at either the valley or the peak of the boost carrier.

FIG. 6 is an explanatory diagram showing an example of a state in which the upper single element control is switched to the double element control when the duty command D * is equal to or higher than the threshold value Dreff. In the modified example, as shown in the middle part of FIG. 6, by switching from the upper single element control to the double element control at the timing of the peak (maximum value) of the boost carrier, the upper arm is turned off and the lower arm is turned on. The interval ΔT2 from the timing to be performed is shorter than the above-mentioned dead time DT. If this interval is shortened, the positive electrode side line and the negative electrode side line of the high voltage side power line 42 may be short-circuited. On the other hand, in the embodiment, as shown in the lower part of FIG. 6, the upper arm is turned off by switching from the upper single element control to the double element control at the timing of the valley (minimum value) of the boost carrier. The timing at which the lower arm is turned on can be shifted by the dead time DT, and it is possible to suppress a short circuit between the positive electrode side line and the negative electrode side line of the high voltage side power line 42. When switching from the lower single element control to the double element control when the duty command D * is equal to or higher than the threshold Dref, if the switch is made at the peak of the boost carrier, the lower arm will continue to be turned on before and after the switching. Since the possibility that the positive electrode side line and the negative electrode side line of the high voltage side power line 42 are short-circuited is sufficiently low, it is considered that switching may be performed at either the peak or the valley of the boost carrier.

In the booster system mounted on the electric vehicle 20 of the above-described embodiment, when switching from single-element control (upper single-element control or lower single-element control) to double-element control, the duty command D * is equal to or higher than the threshold value Dref. Occasionally, single-element control is switched to double-element control at the timing of the valley of the boost carrier (minimum value), and when the duty command D * is less than the threshold value Dref, both are changed from single-element control at the timing of the peak (maximum value) of the boost carrier. Switch to element control. As a result, the interval between the timing when the lower arm is turned off and the timing when the upper arm is turned on when switching from the lower single element control to the dual element control, and the upper arm when switching from the upper single element control to the dual element control. It is possible to suppress that the interval between the timing of turning off and the timing of turning on the lower arm becomes shorter than the dead time DT. As a result, it is possible to prevent the positive electrode side line and the negative electrode side line of the high voltage side power line 42 from being short-circuited.

In the embodiment, the drive device is mounted on the electric vehicle 20 including the motor 32. However, it may be in the form of a drive device mounted on a hybrid vehicle including an engine in addition to the motor 32, or may be in the form of a drive device mounted on a moving body such as a vehicle, a ship, or an aircraft other than the automobile. It may be in the form of a drive device mounted on non-moving equipment such as construction equipment.

The correspondence between the main elements of the examples 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 "boost converter" and the electronic control unit 50 corresponds to a "control device".

Regarding the correspondence between the main elements of the examples and the main elements of the invention described in the column of means for solving the problem, the invention described in the column of means for solving the problem in the examples is carried out. Since it is an example for specifically explaining the form for solving the problem, the elements of the invention described in the column of means for solving the problem are not limited. That is, the interpretation of the invention described in the column of means for solving the problem should be performed based on the description in the column, and the examples are the inventions described in the column of means for solving the problem. It is just a concrete example.

Although the embodiments for carrying out the present invention have been described above with reference to examples, the present invention is not limited to these examples, and various embodiments are used without departing from the gist of the present invention. Of course, it can be done.

The present invention can be used in the manufacturing industry of boosting systems and the like.

20 electric vehicle, 22a, 22b drive wheel, 24 differential gear, 26 drive shaft, 32 motor, 32a rotation position detection sensor, 32u, 32v current sensor, 34 inverter, 36 battery, 36a voltage sensor, 36b current sensor, 40 boost converter , 40a current sensor, 42 high voltage side power line, 44 low voltage side power line, 46,48 condenser, 46a, 48a voltage sensor, 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, D11 to D16, D31, D32 diode, L reactor, T11 to T16, T31, T32 Transistor.

Claims (1)

A buck-boost that has first and second switching elements as upper and lower arms, first and second diodes, and a reactor, and exchanges power with voltage conversion between the power supply side and the electric load side. With a converter
As the control of the buck-boost converter based on the comparison result between the duty command and the step-up carrier, one-element control that switches only one of the first and second switching elements or the first and second switching elements. A control device that executes both element control that switches both elements,
It is a booster system equipped with
When switching from the one-element control to the two-element control, the control device switches from the one-element control to the two-element control at the timing of the minimum value of the boost carrier when the duty command is equal to or higher than the threshold value. When the duty command is less than the threshold value, the single element control is switched to the double element control at the timing of the maximum value of the boost carrier.
Boost system.

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