JP4727248B2 - Control device for inverter and converter - Google Patents

Description

This invention relates to a control device of the inverter and the converter.

Conventionally, a motor control device that drives and controls a three-phase motor is known. The motor control device includes an inverter circuit for driving the motor, and performs drive control of the motor by a switching element of the inverter circuit.
In such a motor control device, since the driving current of the motor is controlled by turning on / off the switching element, switching noise is likely to occur, and particularly when a plurality of motors are driven simultaneously, the switching noise tends to increase. is there. Therefore, in order to reduce such switching noise in the motor control device, an inverter circuit is individually provided for a plurality of three-phase motors to reduce the energization current per one switching element and to reduce the switching current. There exists what suppresses noise (for example, refer patent document 1).
JP 2003-174790 A

An example of this will be described with reference to FIG. In FIG. 7, one phase of the two inverter circuits connected in parallel is collectively shown as an inverter circuit 74, and the motor coils 79 of the two motors connected thereto are each only one phase. It is described.
In the figure, a smoothing capacitor 73 is connected in parallel to a DC power source 72 such as a battery. The smoothing capacitor 73 is connected in parallel with two switching elements 76 connected in series, and diodes 77 and 77 are connected in parallel to the switching elements 76 and 76, respectively. The smoothing capacitor 73, the switching element 76, and the diode 77 constitute an inverter circuit 74.
A plurality of motor coils 79 are connected to the switching element 76. By alternately switching the switching element 76, the voltage of the DC power source 72 is converted into AC and applied to the motor coil 79. At this time, by providing the inverter circuit 74 for each motor, the current supplied to each switching element 76 is diverted by the number of the inverter circuits 74, so that the switching noise is reduced.

However, in the conventional motor control device, since a ripple current having an amplitude d sufficiently larger than the switching noise shown in FIG. 8 is generated, the loss in the smoothing capacitor 73 cannot be sufficiently reduced. As a result, there is a problem that the smoothing capacitor 73 is burdened.
If the load on the smoothing capacitor 73 is to be reduced, the smoothing capacitor 73 having a large capacity is required, which increases the size of the smoothing capacitor 73 and increases the cost.
Accordingly, the invention is to reduce the ripple current due to switching downsizing of the smoothing capacitor to provide a control device for relief to Louis inverter and converter burden of the smoothing capacitor.

In order to solve the above-described problem, the invention described in claim 1 includes at least an inverter (for example, the first inverter circuit 4 in the embodiment) and a DC / DC converter (for example, the first DC / DC converter in the embodiment). 13) and a smoothing capacitor (for example, the smoothing capacitor 3 in the embodiment) that is shared between the inverter and the DC / DC converter and smoothes the current supplied from the power source. And a control means (including a smoothing capacitor (for example, the smoothing capacitor 3 in the embodiment) for smoothing the current supplied from the power source, and for varying the switching carrier phase between the inverter and the DC / DC converter ( for example, the gate control circuit 10) in the embodiment, the torque of the motor The inverter having a minimum ripple current when the carrier phase at the operating point of the inverter based on the number of rotations and the carrier phase at the operating point of the DC / DC converter based on the output current value and the output voltage value are added. And a phase difference map that stores a switching carrier phase difference between the DC / DC converter and the control means refers to the phase difference map and either one of the inverter and the DC / DC converter. The switching carrier phase at the operating point is used as a reference, and the switching carrier phase of either the inverter or the DC / DC converter is controlled to a phase difference at which the ripple current becomes a minimum value .

The invention described in claim 2 is characterized in that the smoothing capacitor is provided in the vicinity of the inverter and the DC / DC converter.
With this configuration, the ripple current can be suppressed by reducing the line inductance between the inverter or the DC / DC converter and the smoothing capacitor.

According to the first aspect of the present invention, since the ripple current of the smoothing capacitor can be reduced by shifting the switching carrier phases of the inverter and the DC / DC converter, the capacity of the smoothing capacitor can be set small. Therefore, there is an effect that the cost can be reduced and the smoothing capacitor can be miniaturized to improve the degree of freedom of arrangement.

According to the second aspect of the invention, in addition to the effect of the first aspect , the ripple current can be suppressed by reducing the line inductance between the inverter or the DC / DC converter and the smoothing capacitor. Therefore, there is an effect that it is possible to further reduce the size of the smoothing capacitor by reducing the burden on the smoothing capacitor.

Next, a first reference example will be described with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a motor control device for a vehicle such as a hybrid vehicle or an electric vehicle. The motor control device 1 performs drive control of a motor M, which will be described later, using electric power supplied from a battery 2 that is a DC power source. The battery 2 is connected to the motor control device 1. The motor control device 1 includes a first inverter circuit (inverter) 4 and a second inverter circuit (inverter) 5 connected in parallel. The first inverter circuit 4 and the second inverter circuit 5 share a smoothing capacitor 3. The smoothing capacitor 3 smoothes the power supplied from the battery 2 and generates external noise superimposed on the power supply. It has been removed.

  The first inverter circuit 4 and the second inverter circuit 5 are configured by connecting two bipolar type transistors 6 as switching elements in series, and an arm 8 for one phase in which a diode 7 is connected in parallel to each of these transistors 6. Is connected to the smoothing capacitor 3 in parallel for three phases. A coil 9 of each phase of the motor M is connected between the transistors 6 connected in series. In the arm 8, the transistor 6 has a collector connected to the + side of the battery 2 and an emitter connected to the − side, and the diode 7 is connected in a forward direction from the emitter to the collector of the transistor 6. .

  The smoothing capacitor 3 of the first inverter circuit 4 and the second inverter circuit 5 is disposed in the vicinity of the arm 8 described above. Specifically, since the first inverter circuit 4 and the second inverter circuit 5 perform a switching operation and perform intermittent energization, for example, when the smoothing capacitor 3 is separated from each arm 8, The inductance component of the line connecting the smoothing capacitor 3 and each arm 8 increases. Therefore, the ripple current increases due to the counter electromotive force of the inductance. In other words, by arranging the smoothing capacitor 3 in the vicinity of each arm 8, the influence of the inductance generated in the line is suppressed.

  A gate control circuit (control circuit) 10 is connected to the first inverter circuit 4 and the second inverter circuit 5. The gate control circuit 10 controls the switching operation between the first inverter circuit 4 and the second inverter circuit 5 by a gate signal output from the gate control circuit 10. The gate control circuit 10 stores a map of a switching carrier phase difference at which a ripple current described later has a minimum value. The gate control circuit 10 is connected to a drive command circuit (ECU) 11 that outputs a required torque and a rotational speed command of the motor M to the gate control circuit 10.

  Next, switching control between the first inverter circuit 4 and the second inverter circuit 5 will be described with reference to FIGS. Similar to FIG. 7, FIG. 2 shows only one phase of the two three-phase motors M shown in FIG. 1 in a simplified manner. For the sake of illustration, the smoothing capacitors 3 of the first inverter circuit 4 and the second inverter circuit 5 are individually shown.

  As shown in FIG. 2, when the first inverter circuit 4 performs a switching operation, a DC current A that is an inverter current is passed through the first inverter circuit 4. On the other hand, when the second inverter circuit 5 performs a switching operation, a DC current B that is an inverter current is supplied to the second inverter circuit 5. A ripple current obtained by adding the DC current A and the DC current B enters and exits the smoothing capacitor 3. In the first inverter circuit 4 and the second inverter circuit 5, the switching timing of the transistor 6 is controlled by the drive command circuit 11 so as to shift the carrier phases of the DC current A and the DC current B.

  FIGS. 3 and 4 show changes in DC current A and DC current B and changes in ripple current obtained by adding DC current A and DC current B when the vertical axis represents current and the horizontal axis represents current phase. Yes. 3 and 4, the first inverter circuit 4 and the second inverter circuit 5 are controlled by shifting the switching carrier phase difference, which is the phase difference between the DC current A and the DC current B, by 90 °, for example. is there. That is, the phase of the DC current A and the DC current B is controlled so that the upper limits of the DC current A and the lower limit of the DC current B coincide with each other without matching the timing of the upper limits of the current values of the DC current A and DC current B. Is set to cancel the amplitude of. Therefore, as shown in FIG. 4, the amplitude D of the ripple current obtained by adding the DC current A and the DC current B is smaller than the amplitude d of the ripple current of FIG. The current phase on the horizontal axis in FIGS. 3 and 4 may be replaced with time.

Next, calculation of the switching carrier phase difference will be described with reference to FIGS.
FIG. 5 shows a range of operating points at which the motor M can be continuously operated, where the vertical axis represents the torque of the motor M and the horizontal axis represents the number of rotations of the motor M. This range of operating points is unique to each motor, and the required operating point of the motor M is normally set in a range below the upper limit value (indicated by the solid line in FIG. 5). Here, in FIG. 5, three operating points, for example, operating point A (indicated by a circle), operating point B (indicated by a triangle), and operating point C (indicated by a square) are set in a range below the upper limit. The operation point A and the operation point B show the case where the required torque is changed at the same rotation speed, and the operation point C shows the case where the rotation speed and the torque are maximized within the range where continuous operation is possible. ing.

  In FIG. 6, the vertical axis represents the ripple current effective value, and the horizontal axis represents the respective switching carrier phase differences energized by the motors M. Operation point A (indicated by ◯), operation point B (indicated by Δ), operation Point C (indicated by □) is a map showing fluctuations in the ripple current effective value for each switching carrier phase difference. For example, in the case of operation point A, the effective value of the ripple current is 0 ° switching carrier phase difference. And the switching carrier phase difference is minimum at 60 °. At this time, the effective value of the ripple current is reduced by a when the switching carrier phase difference is 60 ° than when the switching carrier phase difference is 0 °. Similarly, in the case of operation point B, the ripple current effective value is maximum when the switching carrier phase difference is 0 °, and the ripple current effective value is minimum when the switching carrier phase difference is 180 °, and is reduced by b. In the case of the operation point C, the ripple current effective value is maximum when the switching carrier phase difference is 0 °, and is minimum when the switching carrier phase difference is 90 °, and is reduced by c. The upper limit value of the capacity of the smoothing capacitor 3 may be set based on the minimum value of the ripple current at the operating point at which the ripple current is maximum.

  That is, the gate control circuit 10 refers to the map shown in FIG. 6 stored in advance in the gate control circuit 10 and operates based on the required torque and the rotational speed command output from the drive command circuit 11. Determine. Then, the switching carrier phase difference that minimizes the ripple current at the operation point determined by the map is calculated, and the first inverter circuit 4 and the second inverter circuit 5 are controlled based on the calculation result.

Therefore, according to the first reference example described above, the ripple current can be reduced by shifting the phases of the switching carriers of the first inverter circuit 4 and the second inverter circuit 5 by the control command from the gate control circuit 10. The capacitance of the capacitor 3 can be set small, so that the cost can be reduced and the smoothing capacitor 3 can be downsized to improve the degree of freedom in arrangement.

Further, based on a map stored in advance in the gate control circuit 10, an optimum switching carrier phase difference at which the ripple current is always minimized is selected for each operation point determined by the torque and the rotational speed of the motor M. Therefore, the burden on the smoothing capacitor 3 can be reduced.
Further, since the ripple current can be suppressed by reducing the inductance between the first inverter circuit 4 and the second inverter circuit 5 and the smoothing capacitor 3, the burden on the smoothing capacitor 3 is reduced. Further downsizing of the smoothing capacitor 3 can be achieved.

Next, a second reference example of the present invention will be described with reference to FIGS. The second reference example, the first inverter circuit 4 of the first reference example described above, since the second inverter circuit 5 is replaced by a DC / DC converter respectively, the same reference numerals to the same parts explain.

  In FIG. 9, reference numeral 12 denotes a converter control device for a vehicle such as an automobile. The converter control device 12 includes a battery 2 as a DC power source, auxiliary equipment (not shown) that is a low-voltage load, and auxiliary equipment. A machine low voltage battery (not shown) is connected. The converter control device 12 includes a first DC / DC converter (DC / DC converter) 13 and a second DC / DC converter (DC / DC converter) 14. Two DC / DC converters 14 are connected to the battery 2 in parallel.

  The first DC / DC converter 13 and the second DC / DC converter 14 share the smoothing capacitor 3 connected in parallel to the battery 2. The smoothing capacitor 3 is disposed in the vicinity of the first DC / DC converter 13 and the second DC / DC converter 14, and the smoothing capacitor 3 smoothes and removes external noise superimposed on the output of the battery 2. It has come to be. Here, the converter control device 12 includes the first DC / DC converter 13, the second DC / DC converter 14, a gate control circuit 10, which will be described later, and a drive command circuit 11.

  The first DC / DC converter 13 and the second DC / DC converter 14 have two bipolar type transistors 6 as switching elements connected in series, and an arm 8 in which a diode 7 is connected in parallel to each of these transistors. There are two sets each, and these arms 8 are connected to the battery 2 in parallel. A primary winding 16 of the winding transformer 15 is interposed between the transistors 6 and 6 constituting each arm 8.

Here, similarly to the first inverter circuit 4 and the second inverter circuit 5 of the first reference example described above, a gate control circuit 10 that controls the switching operation of the transistor 6 is connected to the transistor 6 of each arm 8. The gate control circuit 10 stores a switching carrier phase difference map (hereinafter simply referred to as a phase difference map) in which the ripple current of the smoothing capacitor 3 is a minimum value. A drive command circuit (ECU) 11 to which a signal from a current voltage sensor (not shown) is input is connected to the gate control circuit 10, and the first DC / DC is connected from the drive command circuit 11 to the gate control circuit 10. Signals relating to the output current and output voltage of the DC converter 13 and the second DC / DC converter 14 are transmitted.

  The winding transformer 15 steps down the AC voltage applied to the input terminal of the primary winding 16 at a predetermined ratio and outputs it from the output terminal of the secondary winding 17. A cathode of a rectifier diode 18 is connected to each output terminal of the secondary winding 17 so that the cathode of the rectifier diode 18 is directed toward the output terminal. After being connected, it is connected to the negative terminal of the low voltage battery or the negative power terminal of the auxiliary equipment via the negative power line 21.

  The winding transformer 15 is a winding transformer with a so-called center tap, and a center tap 19 is provided on the secondary winding 17. The center tap 19 is connected to the plus terminal of the low voltage battery or the plus side power terminal of the auxiliary equipment via the coil 20 and the plus side power line 22. A smoothing capacitor 23 is interposed between the center tap 19 and the anode of the rectifier diode 18. Here, the rectifier diode 18, the coil 20, and the smoothing capacitor 23 constitute a smoothing circuit 24. The winding transformer 15 is not limited to having a center tap. For example, when a transformer without a center tap is used, the rectifier diodes 18 and 18 of the smoothing circuit 24 are replaced with a diode bridge to make a full wave. Rectification may be performed.

  That is, when the transistor 6 of the first DC / DC converter 13 and the second DC / DC converter 14 is switched, the voltage of the battery 2 which is a direct current is converted into an alternating voltage, and this alternating voltage is converted into the winding. Applied to the input terminal of the transformer 15. The AC voltage applied to the input terminal is stepped down by the winding transformer 15 and output from the output terminal. The stepped-down AC voltage is full-wave rectified by the rectifier diode 18. Further, the full-wave rectified voltage is smoothed by a smoothing circuit 24 composed of the smoothing capacitor 23 and the coil 20, and the smoothed DC low voltage is used for the low-voltage battery described above or a complementary circuit. It will be supplied to the machines via the power lines 21 and 22. The first DC / DC converter 13 and the second DC / DC converter 14 are not limited to the same output voltage value, and may output different voltages.

  FIG. 10 shows an example of a map of required operation points of the first DC / DC converter 13 or the second DC / DC converter 14 when the vertical axis is the output voltage and the horizontal axis is the output current. Here, the range of the operation point is unique to each of various DC / DC converters (here, the first DC / DC converter 13 and the second DC / DC converter 14), and is usually an upper limit value (FIG. 10). The required operation point of the DC / DC converter is set in a range lower than (indicated by a solid line). Here, FIG. 10 shows a case where, for example, three operation points A (indicated by a circle), B (indicated by a triangle), and C (indicated by a square) are set as the operation points. And the operation point C is the case of the same output voltage, and the operation point C is a case where the output current is set larger than that of the operation point B. Furthermore, the operation point A shows a case where the output voltage and the output current are both set lower than the operation points B and C.

  With this configuration, the gate control circuit 10 receives the output current and output voltage signals of the first DC / DC converter 13 and the second DC / DC converter 14 from the drive command circuit 11, and the first DC / DC The respective operation points of the DC converter 13 and the second DC / DC converter 14 can be obtained based on a map of requested operation points.

  For example, the switching carrier phase of the first DC / DC converter 13 and the switching carrier of the second DC / DC converter 14 between the first DC / DC converter 13 and the switching carrier phase of the first DC / DC converter 13 at the operation point obtained at this time are used as a reference. The phase difference is controlled by referring to the phase difference map so that the phase of the switching carrier of the second DC / DC converter 14 is shifted to the optimum phase by the gate control circuit 10 so that the ripple current becomes the minimum value. can do. Although the case where the phase of the switching carrier of the first DC / DC converter 13 is used as a reference has been described, the phase difference that minimizes the ripple current is obtained using the switching carrier phase of the second DC / DC converter 14 as a reference. The switching carrier phase of one DC / DC converter 13 may be shifted and controlled.

Therefore, according to the second reference example described above, when the phase of one switching carrier of the first DC / DC converter 13 and the second DC / DC converter is based on the phase difference map, Since the phase of the switching carrier can be changed and controlled so that the ripple current of the smoothing capacitor 3 is minimized, the smoothing shared by the first DC / DC converter 13 and the second DC / DC converter 14 is used. The ripple current of the capacitor 3 can be reduced, and the capacitance of the smoothing capacitor 3 can be set small. As a result, the cost can be reduced, and the smoothing capacitor 3 can be downsized and the degree of freedom in arrangement can be improved. It becomes. Similarly to the first reference example described above, when the capacitance of the smoothing capacitor 3 is not reduced, the burden on the smoothing capacitor 3 can be reduced and the reliability can be improved.

Next, with reference to FIG. 11 illustrating the form of implementation of the present invention. Implementation form of this is because it was replaced with the first DC / DC converter 13 of the second reference example described above the second inverter circuit 5 of the first reference example described above, the same reference numerals to the same parts Will be described. In addition, FIG. 5 of the first reference example is used for the map of the requested operation point of the first inverter circuit 4, and the second reference example described above is used for the map of the requested operation point of the first DC / DC converter 13. This will be described with reference to FIG.

In FIG. 11, reference numeral 25 denotes an inverter and converter control device (hereinafter referred to as a control device) in which the motor control device 1 of the first reference example and the converter control device 12 of the second reference example are combined. The control device 25 is connected to a battery 2 which is a DC power source, a motor M of a vehicle such as a hybrid vehicle or an electric vehicle, and a low voltage load such as a low voltage battery or an auxiliary machine (not shown) of the vehicle. The control device 25 includes a first inverter circuit 4 and a first DC / DC converter 13, and the first inverter circuit 4 and the first DC / DC converter 13 are respectively connected in parallel to the battery 2. Yes.

In the vicinity of each arm 8 of the first inverter circuit 4 and the first DC / DC converter 13, a smoothing capacitor 3 is interposed between terminals of the battery 2, and the smoothing capacitor 3 is connected to the first inverter circuit. 4 and the first DC / DC converter 13. Here, as in the first reference example , by arranging the smoothing capacitor 3 in the vicinity of each arm 8, the line inductance between the smoothing capacitor 3 and each arm 8 is reduced, and the ripple current due to the back electromotive force is reduced. can do. The description of the first inverter circuit 4 and the first DC / DC converter 13 will be omitted because it is a repetition of the first and second reference examples .

  A gate control circuit 10 for controlling the switching operation of the transistor 6 is connected to the first inverter circuit 4 and the first DC / DC converter 13. Further, the gate control circuit 10 is connected to a drive command circuit 11 that outputs a request torque and a rotational speed command of the motor M, and outputs signals related to the output voltage and output current of the first DC / DC converter. Further, the gate control circuit 10 includes a switching carrier phase difference map (not shown: hereinafter simply referred to as a level) between the first inverter circuit and the first DC / DC converter in which the ripple current of the smoothing capacitor 3 becomes the minimum value. Called a phase difference map).

This phase difference map is, for example, for each phase difference between the switching carrier of the first inverter circuit 4 at a predetermined operating point and the switching carrier of the first DC / DC converter 13 at the predetermined operating point. This shows the reduction rate of the effective value of ripple current. Here, the operation point of the first inverter circuit 4 can be obtained by referring to FIG. 5 of the first reference example , while the operation point of the first DC / DC converter 13 is the second operation described above. It can obtain | require by referring FIG. 10 of a reference example . Although the implementation of the form of this been described relative to the switching carrier phase of the first inverter circuit 4, with respect to the switching carrier phase of the first DC / DC converter 13, the first relative phase The switching carrier phase of the inverter circuit 4 may be controlled with reference to the phase difference map.

  Therefore, according to the third embodiment described above, switching control of circuits for different applications such as the first inverter circuit 4 that controls the motor M and the first DC / DC converter 13 that performs step-down control of the battery voltage. Even when the switching operation is performed, the phase difference of each switching carrier is referred to the phase difference map so that the ripple current of the smoothing capacitor 3 is minimized, and the switching operation of each transistor 6 is controlled by the gate control circuit 10. Therefore, the ripple current of the smoothing capacitor 3 can be reduced and the capacitance of the smoothing capacitor 3 can be set small. As a result, the smoothing capacitor 3 can be downsized and the degree of freedom in arrangement can be reduced. Can be improved.

  The present invention is not limited to the above embodiment, and may be used for vehicles other than hybrid vehicles and electric vehicles, for example, and a smoothing capacitor may be provided for each inverter circuit and DC / DC converter. Further, the phase difference of the switching carrier may be obtained by a drive command circuit, or a table may be used in addition to the map. Further, for example, an FET or an IGBT may be used as the transistor of the inverter circuit and the DC / DC converter as long as the switching operation is possible. In the above-described embodiment, the case where a total of two inverter circuits and DC / DC converters are provided has been described. However, a plurality of these may be provided. For example, three or more inverter circuits and DC / DC converters may be combined. Anyway.

It is a circuit diagram of the motor control device in the first reference example of the present invention. It is explanatory drawing of the motor control apparatus in the 1st reference example of this invention. It is a graph which shows the DC current A and the DC current B with respect to time in the first reference example of the present invention. It is a graph which shows DC current with respect to time in the 1st reference example of this invention. It is a graph which shows the torque of the motor with respect to the rotation speed in the 1st reference example of this invention , and embodiment. It is a graph which shows the ripple current effective value with respect to the switching carrier phase difference of the 1st reference example of this invention. It is explanatory drawing of the conventional motor control apparatus. It is a graph which shows DC current with respect to time of the conventional motor control device. It is a circuit diagram of the converter control apparatus in the 2nd reference example of this invention. It is a graph which shows the 2nd reference example of this invention , and the operating point of the DC / DC converter in embodiment. It is a circuit diagram of a control device in the implementation of embodiments of the present invention.

Explanation of symbols

2 Battery 3 Smoothing capacitor 4 First inverter circuit (inverter)
5 Second inverter circuit (inverter)
10 Gate control circuit (control circuit)
13 First DC / DC converter (DC / DC converter)
14 Second DC / DC converter (DC / DC converter)
M motor

Claims (2)

An inverter and converter control device comprising at least an inverter and a DC / DC converter, and a smoothing capacitor that is shared by the inverter and the DC / DC converter and smoothes a current supplied from a power source ,
Control means for making switching carrier phases of the inverter and the DC / DC converter variable respectively ;
The ripple current when the carrier phase at the operating point of the inverter based on the torque and the rotational speed of the motor and the carrier phase at the operating point of the DC / DC converter based on the output current value and the output voltage value is the minimum value. A phase difference map for storing a switching carrier phase difference between the inverter and the DC / DC converter,
The control means refers to the phase difference map, and uses the switching carrier phase at one of the operating points of the inverter and the DC / DC converter as a reference, and switches the other of the inverter and the DC / DC converter. A control device for an inverter and a converter, wherein the carrier phase is controlled to a phase difference at which the ripple current becomes a minimum value . In the vicinity of the inverter and the DC / DC converter, an inverter and a converter control device according to claim 1, characterized in that a said smoothing capacitor.

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