JP6729306B2 - Converter device - Google Patents

Description

The present invention relates to a converter device.

Conventionally, as a converter device of this type, a first power line to which a DC battery is connected and a second power line to which an inverter for driving a motor generator is connected are connected in parallel to each other, and each of them is a switching element switching device. There is proposed a device including two voltage conversion units (step-up converters) for boosting the power of the first power line to supply the power to the second power line, and a capacitor attached to the second power line (for example, , Patent Document 1).

JP, 2012-210138, A

In the above converter device, the switching timings of the switching elements of the two voltage conversion units may overlap. In this case, since the surge voltage becomes large, it is necessary to suppress the voltage exceeding the withstand voltage from being applied to each element of the two voltage conversion units in consideration of this. Moreover, when this countermeasure is taken, it is preferable to use a method capable of suppressing an increase in the loss increase rate of the entire converter device as much as possible.

A converter device of the present invention includes a plurality of boost converters connected in parallel to a low-voltage power line connected to a power storage device and a high-voltage power line connected to an electric load, and a capacitor connected to the high-voltage power line. The main object of the invention is to suppress the increase in loss increase rate of the entire converter device and the application of a voltage exceeding the withstand voltage to each element of the plurality of boost converters.

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
The low-voltage side power line to which the power storage device is connected and the high-voltage side power line to which the electric load is connected are connected in parallel to each other, and the power of the low-voltage side power line is boosted by switching of the switching elements. A plurality of boost converters for supplying to the high-voltage side power line,
A capacitor attached to the high voltage side power line,
Among the plurality of step-up converters, the switching speed of the switching element of the step-up converter having a short path length to the capacitor is faster than the switching speed of the switching element of the step-up converter having a long path length to the capacitor, A control device for controlling the boost converter of
A converter device comprising:
When the switching timings of the switching elements of at least two boost converters of the plurality of boost converters overlap, the control device has the largest path length to the capacitor among the at least two boost converters of the switching timings. Make the switching speed of the switching element of the long boost converter slower,
That is the summary.

In the converter device of the present invention, the switching speed (base speed) of the switching element of the boost converter having a short path length to the capacitor among the plurality of boost converters is set to the switching speed of the switching element of the boost converter having a long path length to the capacitor (base speed). Control multiple boost converters faster than base speed). This is because the smaller the path length to the capacitor among the multiple boost converters, the smaller the parasitic inductance between the boost converter and the capacitor, and the smaller the surge voltage. This is to reduce the loss of the entire converter device. Then, when the switching timings of the switching elements of at least two boost converters of the plurality of boost converters overlap, the switching element of the boost converter having the longest path length to the capacitor among the at least two boost converters of which switching timings overlap. Make the switching speed slower (lower than the base speed). Therefore, the switching speed of the switching element of one boost converter of at least two boost converters having the same switching timing is slowed, so that the surge voltage is prevented from increasing and the breakdown voltage of each boost converter exceeds the withstand voltage. It is possible to suppress application of voltage. Moreover, among at least two boost converters having overlapping switching timings, the switching speed of the boost converter having the longest path length to the capacitor (the boost converter having a slow base speed and a large switching loss) is further reduced (with respect to the base speed). Converter device compared to the one that makes the switching speed slower (makes it slower than the base speed) of the boost converter that makes the path length from the capacitor to the capacitor shorter (the converter that has a faster base speed and a smaller switching loss). It is possible to suppress an increase in the overall loss increase rate. As a result, it is possible to prevent a voltage exceeding the withstand voltage from being applied to each element of the plurality of boost converters while suppressing an increase in the loss increase rate of the entire converter device.

It is a block diagram which shows the outline of a structure of the electric vehicle 20 provided with the converter apparatus as one Example of this invention. It is a flow chart which shows an example of a switching speed change 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 a configuration of an electric vehicle 20 including 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 as a power storage device, step-up converters 40a, 40b, 40c, capacitors 46, 48, an electronic control unit 50, Equipped with. Here, the booster converters 40a, 40b, 40c, the capacitor 48, and the electronic control unit 50 correspond to the converter device of the embodiment.

The motor 32 is configured as, for example, a synchronous generator motor, and is connected to a drive shaft 26 that is connected to the drive wheels 22a and 22b via a differential gear 24. The inverter 34 is used to drive the motor 32 and is connected to the positive electrode side line 44a and the negative electrode side line 44b of the high voltage side power line 44. The motor 32 is rotationally driven by the electronic control unit 50 controlling switching of a plurality of switching elements (not shown) of the inverter 34. The battery 36 is configured as, for example, a lithium ion secondary battery, a nickel hydrogen secondary battery, or a fuel cell, and is connected to the positive electrode side line 42a and the negative electrode side line 42b of the low voltage side power line 42. The capacitor 46 is attached to the positive electrode side line 42a and the negative electrode side line 42b of the low voltage side power line 42. The capacitor 48 is attached to the positive electrode side line 44a and the negative electrode side line 44b of the high voltage side power line 44.

The boost converters 40a, 40b, 40c are connected in parallel to the low voltage side power line 42, the positive side line 42a and the negative side line 42b, and the high voltage side power line 44, the positive side line 44a and the negative side line 44b. .. The boost converters 40a, 40b, 40c are arranged such that the path length to the capacitor 46 becomes longer in this order. Further, boost converters 40a, 40b, 40c respectively include reactors La, Lb, Lc, diodes Da, Db, Dc, and transistors Ta, Tb, Tc as switching elements. One terminal of each of the reactors La, Lb, and Lc is connected to the positive electrode side line 42a of the low voltage side power line 42. The diodes Da, Db, Dc are connected to the other terminals of the reactors La, Lb, Lc and the positive side line 44a of the high-voltage side power line 44 in the order from the reactor La, Lb, Lc side to the positive side line 44a side. It is connected in the direction. The transistors Ta, Tb, Tc are connected to the other terminals of the reactors La, Lb, Lc and the negative voltage lines 42b, 44b of the low voltage side power line 42 and the high voltage side power line 44. The boost converters 40a, 40b, 40c adjust the ratio (duty) of the on-time to the sum of the on-time and the off-time of the transistors Ta, Tb, Tc by the electronic control unit 50 to adjust the low-voltage side power line. The power of 42 is boosted and supplied to the high voltage side power line 44.

Although not shown, the electronic control unit 50 is configured as a microprocessor centered on a CPU, and includes, in addition to the CPU, a ROM for storing a processing program, a RAM 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 the rotational position detection sensor that detects the rotational position of the rotor of the motor 32 or the battery 36 from the voltage sensor attached between the terminals of the battery 36. And the voltage Ib of the battery 36 from the current sensor attached to the output terminal of the battery 36. Further, the voltage VL of the capacitor 46 (low voltage side power line 42) from the voltage sensor 46a mounted between the terminals of the capacitor 46, the capacitor 48 (high voltage side from the voltage sensor 48a mounted between the terminals of the capacitor 48). The voltage VH of the power line 44) can also be mentioned. Further, currents Ia, Ib, Ic of reactors La, Lb, Lc from current sensors 41a, 41b, 41c for detecting currents flowing in reactors La, Lb, Lc of boost converters 40a, 40b, 40c can also be mentioned. In addition, 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, and the accelerator opening from the accelerator pedal position sensor 64 that detects the amount of depression of the accelerator pedal 63. Acc, 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 V from the vehicle speed sensor 68 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 control signals for the plurality of switching elements of the inverter 34 and control signals for the transistors Ta, Tb, Tc of the boost converters 40a, 40b, 40c. .. The electronic control unit 50 calculates the rotation speed Nm of the motor 32 based on the rotation position of the rotor of the motor 32 from the rotation position detection sensor.

In the thus configured electric vehicle 20 of the embodiment, the electronic control unit 50 sets the required torque Td* required for traveling (required for the drive shaft 26) based on the accelerator opening Acc and the vehicle speed V. , The set required torque Td* is set to the torque command Tm* of the motor 32, and the plurality of switching elements of the inverter 34 are controlled 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 44 based on the target operating point (torque command Tm* and rotation speed Nm) of the motor 32, and at the same time, the torque command Tm* of the motor 32. The required electric power Pm of the motor 32 is calculated as the product of the number of revolutions and the number of revolutions Nm. Then, based on the voltage VH and the target voltage VH* of the high voltage side power line 44 and the target power Pm* of the motor 32, from the positive side line 42a of the low voltage side power line 42 to the positive side of the high voltage side power line 44. A total target current IL* is set as a target value of the total current flowing through the side line 44a. Then, based on the total target current IL*, of the boost converters 40a, 40b, 40c, a first mode for driving only the boost converter 40a and a second mode for driving the boost converters 40a, 40b, and the boost converters 40a, 40b. , 40c are driven to set the execution mode. For example, when the total target current IL* is less than or equal to the threshold value ILref1, the first mode is set to the execution mode, and when the total target current IL* is greater than the threshold value ILref1 and less than or equal to the threshold value ILref2, the second mode is set to the execution mode. However, when the total target current IL* is larger than the threshold value ILref2, the third mode is set to the execution mode. The thresholds ILref1 and ILref2 can be set so that the total efficiency of the entire converter device is good.

When the execution mode is set in this way, when the execution mode is the first mode, the current distribution ratios Da, Db, Dc of the reactors La, Lb, Lc of the boost converters 40a, 40b, 40c are set to 1, 0, 0. When the execution mode is the second mode, the values D1, D2, 0 (D1+D2=1) are set to the current distribution ratios Da, Db, Dc of the reactors La, Lb, Lc. Further, when the execution mode is the third mode, the current distribution ratios Da, Db, Dc of the reactors La, Lb, Lc are set to the values D3, D4, D5 (D3+D4+D5=1). The values D1 to D5 may be set to "D1=D2=1/2" and "D3=D4=D5=1/3", for example, or may be set based on the total target current IL*. Good. Note that when the execution mode is switched, the current distribution ratios Da, Db, Dc, and by extension, the current distribution ratios Da, Db, Dc are set to "Da+Db+Dc=1" in order to avoid sudden changes in the target duties Da, Db, Dc described later. It is assumed that the rate is gradually changed while maintaining the rate. For example, when the execution mode is switched from the second mode to the third mode, the current distribution ratios Da, Db, Dc are gradually changed from the values D1, D2, 0 to the values D3, D4, D5.

When the current distribution ratios Da, Db, Dc of the reactors La, Lb, Lc are set in this way, the total target current IL* is multiplied by the current distribution ratios Da, Db, Dc of the reactors La, Lb, Lc to form the reactors La, Lb, Lc. The target currents ILa*, ILb*, and ILc* of are set. Then, the target duties Da, Db, Dc of the transistors Ta, Tb, Tc are set so that the currents ILa, ILb, ILc flowing through the reactors La, Lb, Lc become the target currents ILa*, ILb*, ILc*. Then, the switching control signal based on the target duty Da, Db, Dc and the switching speeds Sa, Sb, Sc of the transistors Ta, Tb, Tc are output to each driver IC (not shown) corresponding to the transistors Ta, Tb, Tc. .. Each driver IC controls switching of the corresponding transistor at a switching speed based on the switching control signal. When the target duty is 0, the switching control signal is a signal for holding the transistor in the off state, so the driver IC holds the corresponding transistor in the off state.

Here, the switching speeds Sa, Sb, Sc of the transistors Ta, Tb, Tc are basically set to the base speeds Saba, Sbba, Scca. The base speeds Saba, Sbba, Scca are set to be slower in the order of the transistors Ta, Tb, Tc. This is because the shorter the path length of the boost converters 40a, 40b, 40c (transistors Ta, Tb, Tc) to the capacitor 48, the smaller the parasitic inductance between the boost converter (transistor) and the capacitor 48 and the smaller the surge voltage. This is because the switching loss of the transistor is reduced to reduce the loss of the converter device as a whole.

Further, in the embodiment, when the execution mode is the second mode, the switching control of the transistors Ta and Tb is performed, and when the execution mode is the third mode, the switching control of the transistors Ta, Tb and Tc is performed. In order to avoid overlapping timings, the on timings are staggered from each other. For example, when the execution mode is the second mode, the ON timings of the transistors Ta and Tb are shifted from each other by 1/2 cycle, and when the execution mode is the third mode, the ON timings of the transistors Ta and Tb are shifted from each other by 1/3 cycle. Can be

Next, the operation of the electric vehicle 20 of the embodiment thus configured, particularly, the operation when switching the switching speed of the transistors Ta, Tb, Tc of the boost converters 40a, 40b, 40c during switching control will be described. FIG. 2 is a flowchart showing an example of a switching speed switching routine executed by the electronic control unit 50 of the embodiment. This routine is repeatedly executed.

When the switching speed switching routine is executed, the electronic control unit 50 determines whether or not the off timings of at least two transistors of the transistors Ta, Tb, and Tc overlap (step S100). This determination can be made, for example, based on the target duties Da, Db, Dc of the transistors Ta, Tb, Tc and the on-timing deviations of the transistors Ta, Tb, Tc that perform switching control. ..

If the OFF timings of at least two transistors among the transistors Ta, Tb, and Tc do not overlap in step S100, this routine is ended as it is. In this case, as described above, the base speeds Saba, Sbba, Scca are set to the switching speeds Sa, Sb, Sc.

When the off timings of at least two transistors among the transistors Ta, Tb, and Tc overlap in step S100, it is determined whether or not the transistors Tc are included in the transistors whose off timings overlap (step S110). The case where the transistor Tc is included includes a case where the off timings of the transistors Ta and Tc overlap, a case where the off timings of the transistors Tb and Tc overlap, and a case where the off timings of the transistors Ta, Tb, and Tc overlap. Can be mentioned. Further, as a case where the transistor Tc is not included, a case where the transistors Ta and Tb overlap can be cited.

In step S110, when the transistor Tc is included in the transistors having the same off-timing, the switching speed Sc of the transistor Tc (transistor of the boost converter having the longest path length to the capacitor 48 among the transistors having the same off-timing) is set as the base speed. It is determined that it is later than Scba (step S120), and this routine is ended. In this case, the base speeds Saba and Sbba are set to the switching speeds Sa and Sb, and a speed slower than the base speed Scba is set to the switching speed Sc.

In step S110, when the transistor having the same off-timing does not include the transistor Tc, the switching speed Sb of the transistor Tb (the transistor of the boost converter having the longest path length to the capacitor 48 among the transistors having the same off-timing) is used as the base. When it is determined that the speed is slower than the speed Sbbc (step S130), this routine ends. In this case, the base speeds Saba and Scba are set to the switching speeds Sa and Sc, and the switching speed Sb is set to a speed slower than the base speed Sbba.

Thus, when the off timings of at least two transistors of the transistors Ta, Tb, and Tc overlap, the switching speed of any of the transistors whose off timings overlap is delayed with respect to the base speed. As a result, it is possible to prevent the surge voltage from increasing and to prevent the voltage exceeding the withstand voltage from being applied to each element of boost converters Ta, Tb, and Tc. Moreover, when the transistor Tc is included in the transistors whose off-timing overlaps, the switching speed Sc of the transistor Tc is slower than the base speed Scba, and when the transistor Tc is not included, the switching speed Sb of the transistor Tb is higher than the base speed Sbba. Slow down too. That is, the switching speed of the transistor of the step-up converter, which has the longest path length to the capacitor 48 among the transistors having the same off-timing, is made slower than the base speed. As a result, it is possible to suppress an increase in the loss increase rate of the converter device as a whole, as compared with the case where the switching speed of the transistor of the boost converter having a short path to the capacitor 48 is slowed. As a result, it is possible to suppress an increase in the loss increase rate of the entire converter device and prevent a voltage exceeding the withstand voltage from being applied to each element of the boost converters 40a, 40b, 40c.

In the converter device mounted in the electric vehicle 20 of the embodiment described above, when at least two transistors among the transistors Ta, Tb, and Tc have the same off-timing, up to the capacitor 48 among the transistors having the same off-timing. The switching speed of the transistor of the boost converter with the longest path length is made slower than the base speed. As a result, it is possible to suppress an increase in the loss increase rate of the converter device as a whole and to prevent a voltage exceeding the withstand voltage from being applied to each element of the boost converter.

In the electric vehicle 20 of the embodiment, the on timings of the transistors Ta, Tb, Tc are shifted so as not to overlap each other, but the transistors Ta, Tb, Tc are turned off so as not to overlap each other. The timing may be shifted. In this case, the on-timing of at least two of the transistors Ta, Tb, and Tc may overlap. Therefore, when at least two of the transistors Ta, Tb, and Tc have the same on-timing, the switching speed of the transistor of the boost converter having the longest path length to the capacitor 48 among the transistors having the same on-timing is set to the base speed. And slow it down. As a result, the same effect as that of the embodiment can be obtained.

In the electric vehicle 20 of the embodiment, the case where at least two transistors among the transistors Ta, Tb, and Tc have the same off-timing has been described. However, the on-timing of one of the transistors Ta, Tb, and Tc is different from the other. When one or two off-timings of the same overlap, or when the on-timing of two transistors and the off-timing of one transistor overlap, the increase rate of loss of the entire converter device among the overlapping transistors increases. It is preferable to make the switching speed of the transistor, which is more suppressed, slower than the base speed.

In the converter device mounted on the electric vehicle 20 of the embodiment, the boost converter 40a includes the reactor La, the diode Da, and the transistor Ta as a switching element. In addition to these, the boost converter 40a is connected in parallel with the diode Da. And a diode connected in parallel to the transistor Ta such that the direction from the negative line 42b, 44b side to the connection point side of the reactor La and the diode Da is the forward direction. May be The same applies to boost converters 40b and 40c. In this case, the boost converters 40a, 40b, 40c can step up the power of the low voltage side power line 42 and supply it to the high voltage side power line 44, and step down the power of the high voltage side power line 44. It can also be supplied to the low voltage side power line 42.

In the converter device mounted on the electric vehicle 20 of the embodiment, the boost converters 40a, 40b, 40c are connected to the low voltage side power line 42 and the high voltage side power line 44 in parallel with each other. The number may be two or four or more.

In the electric vehicle 20 of the embodiment, the battery 36 is used as the power storage device, but a capacitor may be used.

In the embodiment, the converter device is configured to be mounted on the electric vehicle 20 including the traveling motor 32, but the converter device may be configured to be mounted on a hybrid vehicle including an engine in addition to the traveling motor. The converter device may be configured to be mounted on a moving body other than an automobile, or the converter device may be configured to be installed in stationary 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 boost converters 40a, 40b, 40c correspond to "a plurality of boost converters", the capacitor 48 corresponds to a "capacitor", and the electronic control unit 50 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 that the embodiment implements the invention 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.

The embodiments for carrying out the present invention have been described above with reference to the embodiments. However, 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 wheels, 24 differential gear, 26 drive shaft, 32 motor, 34 inverter, 36 battery, 40a, 40b, 40c boost converter, 41a, 41b, 41c current sensor, 41c current sensor, 42 low voltage Side power line, 42a, 44a positive side line, 42b, 44b negative side line, 44 high voltage side power line, 46, 48 capacitor, 46a, 48a voltage sensor, 50 electronic control unit, 60 ignition switch, 61 shift lever, 62 Shift position sensor, 63 shift position SP, accelerator pedal, 64 accelerator pedal position sensor, 65 brake pedal, 66 brake pedal position sensor, 68 vehicle speed sensor.

Claims (1)

The low-voltage side power line to which the power storage device is connected and the high-voltage side power line to which the electric load is connected are connected in parallel to each other, and the power of the low-voltage side power line is boosted by switching of the switching elements. A plurality of boost converters for supplying to the high-voltage side power line,
A capacitor attached to the high voltage side power line,
Among the plurality of step-up converters, the switching speed of the switching element of the step-up converter having a short path length to the capacitor is faster than the switching speed of the switching element of the step-up converter having a long path length to the capacitor, A control device for controlling the boost converter of
A converter device comprising:
When the switching timings of the switching elements of at least two boost converters of the plurality of boost converters overlap, the control device has the largest path length to the capacitor among the at least two boost converters of the switching timings. Make the switching speed of the switching element of the long boost converter slower,
Converter device.

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