JP2017158373A - Control method for multi-phase step-up converter, and multi-phase step-up converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of the control method for conventional multi-phase step-up converters in which a multi-phase step-up converter is incapable of being activated while keeping a state maximizing power efficiency.SOLUTION: A control method for a multi-phase step-up converter includes: a map preparation step of previously preparing a map showing correspondence between the number of driven phases with which power efficiency of the multi-phase step-up converter is to be maximized and input current to the multi-phase step-up converter, for each of different output voltage values; map selection steps (S1, S2) of detecting output voltage of the multi-phase step-up converter before selecting one of maps on the basis of the detected output voltage; and the-number-of-driven-phases selection steps (S3 to S5) of detecting input current of the multi-phase step-up converter before selecting the number of driven phases with which the power efficiency of the multi-phase step-up converter is to be maximized at the detected input current, on the basis of the selected map.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a control method for a multiphase boost converter, for example, a control method for a multiphase boost converter in which a plurality of boost converters are connected in parallel and the plurality of boost converters are controlled by a plurality of drive signals having different phases.

  There is a multiphase boost converter in which a plurality of boost converters are connected in parallel to one of the boost converters, and the plurality of boost converters are controlled by a plurality of drive signals having different phases. Since the multiphase boost converter can reduce the load equivalent to 1 at a higher load than the single phase boost converter, the multiphase boost converter can be downsized. An example of this multiphase boost converter is disclosed in Patent Document 1.

JP 2009-163948 A

  In the control method of the multiphase boost converter described in Patent Document 1, the number of drive phases is switched at a timing when the input power to the multiphase boost converter exceeds a predetermined reference value. Specifically, the reference value is set in advance as an input power value at which supply power to a load (for example, a motor) is insufficient. Therefore, when the technique described in Patent Document 1 is used, there is a possibility that the power efficiency of the multiphase boost converter cannot always be maintained in a high state.

  The present invention has been made in view of the above circumstances, and an object thereof is to maintain high power efficiency of a multiphase boost converter.

  One aspect of a control method for a multi-phase boost converter according to the present invention is a control method for a multi-phase boost converter having a plurality of boost circuits connected in parallel to an output terminal from which an output voltage supplied to a load circuit is output. A map preparation step for preparing in advance a map showing the correspondence between the number of drive phases in which the power efficiency of the multiphase boost converter is highest and the input current to the multiphase boost converter for each different output voltage value; A map selection step of detecting the output voltage of the multiphase boost converter and selecting one of the maps based on the detected output voltage; and detecting and selecting the input current of the multiphase boost converter And a drive phase number selection step of selecting the number of drive phases where the power efficiency is highest in the detected input current based on the map.

  According to the above aspect of the present invention, high power efficiency is maintained because the multi-phase boost converter is controlled while selecting the number of drive phases with the highest power efficiency at that time regardless of the magnitude of the input power. A multi-phase control converter can be operated.

  Another aspect of the control method of the multi-phase boost converter according to the present invention is to control a multi-phase boost converter having a plurality of boost circuits connected in parallel to an output terminal from which an output voltage supplied to a load circuit is output. The frequency of drive signals applied to the plurality of booster circuits is a carrier frequency, and the number of drive phases in which the power efficiency of the multiphase boost converter is highest for each of the different carrier frequencies and the number of drive phases to the multiphase boost converter. A map preparing step of preparing a map showing a correspondence with an input current in advance; a map selecting step of selecting one of the maps based on the current carrier frequency of the multiphase boost converter; and the multiphase boost converter The input current is detected, and based on the selected map, the power efficiency is the highest in the detected input current. Has a number of drive phases selecting step of selecting the dynamic phase number, the.

  According to the above aspect of the present invention, high power efficiency is maintained because the multi-phase boost converter is controlled while selecting the number of drive phases with the highest power efficiency at that time regardless of the magnitude of the input power. A multi-phase control converter can be operated.

  According to the control method of the multiphase boost converter according to the present invention, the multiphase boost converter can be operated while maintaining the power efficiency of the multiphase boost converter high.

1 is a block diagram of a system including a multiphase boost converter according to a first embodiment; FIG. 4 is a diagram for explaining a configuration of a map used in the multiphase boost converter according to the first embodiment. 3 is a flowchart for explaining a control procedure of the multiphase boost converter according to the first embodiment; 3 is a graph for explaining hysteresis control used in the control of the multiphase boost converter according to the first embodiment; FIG. 7 is a diagram for explaining a configuration of a map used in the multiphase boost converter according to the second embodiment. 6 is a flowchart for explaining a control procedure of the multiphase boost converter according to the second embodiment; FIG. 10 is a diagram for explaining a configuration of a map used in the multiphase boost converter according to the third embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. For clarity of explanation, the following description and drawings are omitted and simplified as appropriate. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted as necessary.

  First, FIG. 1 shows a schematic diagram of a system 1 including a multiphase boost converter according to a first embodiment. As shown in FIG. 1, the system 1 according to the first embodiment includes an input power supply 10, a multiphase boost converter 11, and a power control unit 20.

  The input power supply 10 is, for example, a fuel cell. In the system 1, the input voltage Vin generated by the fuel cell 10 is boosted by the multiphase boost converter 11 to generate an output voltage VH to be supplied to the power control unit 20. That is, the power control unit 20 is a load circuit for the multiphase boost converter 11. The multiphase boost converter 11 drives a plurality of booster circuits with a plurality of drive signals having the same frequency with respect to an output terminal from which an output voltage supplied to a load circuit (for example, the power control unit 20) is output. is there. The power control unit 20 also includes a boost converter that boosts the in-vehicle high-voltage battery voltage to the system voltage, and an inverter that converts a DC voltage into an AC voltage and drives a motor that is a power source of the vehicle.

  Multiphase boost converter 11 includes reactors L1 to L4, diodes D1 to D4, drive transistors STr1 to STr4, control unit 12, current detection unit 13, output voltage detection unit 14, and capacitor C1. In the multiphase boost converter 11, one booster circuit is formed by one reactor, one diode, and one drive transistor.

  In the example shown in FIG. 1, one end of each of reactors L <b> 1 to L <b> 4 is connected to the input terminal of multiphase boost converter 11. Diode D 1 has an anode connected to the other end of reactor L 1 and a cathode connected to the output terminal of multiphase boost converter 11. Diode D2 has an anode connected to the other end of reactor L2, and a cathode connected to the output terminal of multiphase boost converter 11. Diode D3 has an anode connected to the other end of reactor L3 and a cathode connected to the output terminal of multiphase boost converter 11. Diode D4 has an anode connected to the other end of reactor L4 and a cathode connected to the output terminal of multiphase boost converter 11.

  The drive transistor STr1 has a collector connected between the reactor L1 and the diode D1, an emitter connected to the ground wiring, and a U-phase drive signal SCu supplied to the base. The drive transistor STr2 has a collector connected between the reactor L2 and the diode D2, an emitter connected to the ground wiring, and a V-phase drive signal SCv applied to the base. The drive transistor STr3 has a collector connected between the reactor L3 and the diode D3, an emitter connected to the ground wiring, and a W-phase drive signal SCw applied to the base. The drive transistor STr4 has a collector connected between the reactor L4 and the diode D4, an emitter connected to the ground wiring, and an X-phase drive signal SCx applied to the base.

  In the system 1 according to the first embodiment, the capacitor C1 is disposed at the output terminal of the multiphase boost converter 11, and the capacitor C2 is disposed at the input terminal of the power control unit 20. Capacitor C1 smoothes the output voltage of multiphase boost converter 11. The capacitor C <b> 2 is a bypass capacitor that suppresses fluctuations that occur according to the current consumption of the power control unit 20 in the voltage applied to the power control unit 20.

  The current detection unit 13 is provided on a power supply wiring that connects between the input terminal of the multiphase boost converter 11 and a plurality of booster circuits, and detects the magnitude of the input current input to the multiphase boost converter 11. The current detection unit 13 outputs information on the magnitude of the detected input current as an input current value Iin.

  The output voltage detection unit 14 is provided between the ground wiring and the output wiring of the multiphase boost converter 11 and detects the magnitude of the output voltage of the multiphase boost converter 11. The output voltage detector 14 outputs information on the magnitude of the detected output voltage as an output voltage value VH.

  The control unit 12 is, for example, a microcontroller unit (hereinafter referred to as MCU) in which an arithmetic circuit and peripheral circuits such as a memory, an AD converter, a DA converter, and a timer are housed in one package. The controller 12 drives a plurality of booster circuits with a plurality of drive signals having the same frequency (for example, drive signals SCu, SCv, SCw, SCx). Here, the control unit 12 switches the number of drive phases of the multiphase boost converter 11 by changing the number of drive signals output from the current detection unit 13 to the booster circuit according to the input current value Iin. Further, the control unit 12 has a map group including a plurality of maps provided for different output voltage values VH. This map group is stored in a memory in the control unit 12, for example. Further, the control unit 12 stores a program for controlling a later-described multiphase boost converter 11 in an internal memory, and executes the program by an arithmetic circuit, whereby the multiphase boost converter 11 described below is executed. Shall be controlled.

  Here, the map group stored in the control unit 12 will be described. In the multiphase boost converter 11 according to the first embodiment, a map group is prepared in advance based on the characteristics of the multiphase boost converter 11 measured or predicted at the design stage. Specifically, based on the characteristics of the multiphase boost converter 11, a map is created by determining the correspondence between the number of drive phases where the power efficiency of the multiphase boost converter is highest and the input current to the multiphase boost converter. To do. Further, in the multiphase boost converter 11 according to the first embodiment, a map is created for each different output voltage value, and the plurality of created maps are stored in the memory of the control unit 12 as one map group.

  An example of this map group will be described. FIG. 2 is a diagram for explaining the configuration of the map used in the multiphase boost converter according to the first embodiment. In the graph shown in FIG. 2, the horizontal axis represents the magnitude of the input current, and the vertical axis represents the power efficiency of the multiphase boost converter 11.

  As shown in FIG. 2, the multiphase boost converter 11 has a different input current value at which the power efficiency is highest in the power efficiency curve for each number of drive phases. The power efficiency curve has points that intersect each other, and the input current corresponding to the intersection is referred to as a phase number switching threshold in the control method according to the first embodiment. When the input current is smaller than the phase number switching threshold, the power efficiency is higher when the number of driving phases is smaller, and when the input current is larger than the phase number switching threshold, the power efficiency is higher when the number of driving phases is larger. . Further, as shown in FIG. 2, the conversion efficiency curve of the multiphase boost converter 11 varies depending on the difference in the magnitude of the output voltage value VH.

  The conversion efficiency curve of the multiphase boost converter 11 has the characteristics as described above. Therefore, in the multiphase boost converter 11 according to the first embodiment, a map showing the correspondence between the number of drive phases where the power efficiency of the multiphase boost converter is the highest and the input current to the multiphase boost converter for each output voltage value. create. In the example shown in the upper diagram of FIG. 2, this map corresponds to an input current smaller than the phase number switching threshold TH1a corresponding to the input current value at which the power efficiency curve of one-phase driving and the power efficiency curve of two-phase driving intersect. Designates the number of driving phases selected for one phase, and is between the phase number switching threshold TH2a and the phase number switching threshold TH1a corresponding to the input current value at which the power efficiency curve of two-phase driving and the power efficiency curve of three-phase driving intersect For two input currents, two phases are selected and the number of drive phases is designated, and the phase number switching threshold TH3a and the number of phases corresponding to the input current value at which the power efficiency curve of three-phase drive and the power efficiency curve of four-phase drive intersect For the input current between the switching threshold TH2a, information for designating the number of selected drive phases for three phases, and for designating the number of selected drive phases for four phases for an input current larger than the phase number switching threshold TH3a. Including. That is, the phase number switching threshold is defined as a value corresponding to the input current corresponding to the change point of the number of drive phases where the power efficiency becomes the highest. In the example illustrated in FIG. 2, three maps are created according to the difference in the output voltage value VH, and a map group including the three maps is stored in the memory of the control unit 12.

  Subsequently, a control procedure of the multiphase boost converter 11 according to the first embodiment will be described. FIG. 3 is a flowchart for explaining the control procedure of the multiphase boost converter according to the first embodiment. In the multiphase boost converter 11 according to the first embodiment, it is assumed that the drive phase number switching process shown in FIG. 3 is repeated continuously or intermittently.

  As shown in FIG. 3, in the control method of the multiphase boost converter 11 according to the first embodiment, first, the number of drive phases and the multiphase where the power efficiency of the multiphase boost converter 11 is maximized in the memory of the control unit 12 or the like. Preparations for controlling the multiphase boost converter 11 are made by performing a map preparation step of preparing a map showing the correspondence with the input current value Iin to the boost converter 11 for each different output voltage value VH.

  The multiphase boost converter 11 according to the first embodiment starts the drive phase number switching process after the map preparation step is completed. First, in step S <b> 1, the control unit 12 reads the input current value Iin and the output voltage value VH from the current detection unit 13 and the output voltage detection unit 14. Next, in step S2, the control unit 12 selects one map corresponding to the output voltage value VH from the map group, and refers to the selected map. The control unit 12 detects the output voltage of the multiphase boost converter 11 in steps S1 and S2, and performs a map selection step of selecting one of the maps based on the detected output voltage.

  Next, in step S3, the control unit 12 compares the input current value Iin acquired in the previous cycle with the input current value Iin acquired in the current cycle, and the change in the input current value Iin exceeds the phase number switching threshold. It is determined whether it is a thing. If the change in the input current value In does not exceed the phase number switching threshold value in step S3, the control unit 12 ends the current cycle of the drive phase number switching process. On the other hand, when it is determined in step S3 that the change in the input current value In exceeds the phase number switching threshold, the control unit 12 determines whether or not the input current value Iin exceeds the hysteresis range.

  Here, the hysteresis range used in the control method of the multiphase boost converter 11 according to the first embodiment will be described. FIG. 4 is a graph illustrating hysteresis control used in the control of the multiphase boost converter according to the first embodiment. As shown in FIG. 4, in the control method of the multiphase boost converter 11 according to the first embodiment, the number of drive phases is switched in response to the input current value Iin exceeding the phase number switching threshold, but the hysteresis range is used. The frequency of switching the number of drive phases is suppressed. In the example shown in FIG. 4, a hysteresis range that prohibits switching of the number of phases is set for each of the phase number switching thresholds TH <b> 1 to TH <b> 3 within a range exceeding each phase number switching threshold. In the control method of the multiphase boost converter 11 according to the first embodiment, the switching of the number of drive phases is waited until the input current value Iin exceeds the phase number switching threshold and the input current value Iin is outside the hysteresis range. . By performing such hysteresis control, chattering in which the switching of the number of driving phases is repeated for a short time can be prevented, and the switching control of the number of driving phases can be stabilized.

  In Step S4 described above, when it is determined that the input current value Iin does not exceed the hysteresis range, the control unit 12 ends the current cycle of the drive phase number switching process. On the other hand, when it is determined in step S4 that the input current value Iin has exceeded the hysteresis range, the control unit 12 sets the number of drive phases to the number of drive phases with the highest power efficiency with respect to the input current value Iin acquired in the current cycle. Are switched (step S5). In response to the end of the switching process in step S5, the control unit 12 ends the current cycle of the drive phase number switching process.

  3, the control unit 12 detects the input current of the multi-phase boost converter 11, and the power efficiency is highest in the detected input current based on the selected map. When the drive phase number selection step for selecting the number of drive phases and the selected drive phase number change, the difference between the input current and the phase number switching threshold at that time exceeds a predetermined hysteresis range. A drive phase number switching step of reflecting the selected drive phase number in the control of the multiphase boost converter 11 is performed.

  From the above description, in the control method of the multiphase boost converter 11 according to the first embodiment, the relationship between the input current Iin of the multiphase boost converter 11 and the number of drive phases where the power efficiency becomes high is defined in advance in the map. By referring to this map, the number of drive phases with the highest power efficiency is selected for each input current value Iin. As a result, the multiphase boost converter 11 according to the first embodiment can always be operated with high conversion efficiency.

  In the control method of the multiphase boost converter according to the first embodiment, a map is provided for each output voltage value VH, a map corresponding to the output voltage value VH is selected, and the number of drive phases is determined based on the selected map. . Thereby, the multiphase boost converter 11 according to the first embodiment can prevent the conversion efficiency from being lowered due to the difference in the output voltage value VH.

Embodiment 2
In the second embodiment, another embodiment of a map creation method will be described. FIG. 5 is a diagram for explaining the configuration of the map used in the multiphase boost converter according to the second embodiment. As shown in FIG. 5, the power efficiency curves have different shapes depending on the carrier frequency. Therefore, in the control method of the multiphase boost converter according to the second embodiment, the map group refers to a map group including a map provided for each carrier frequency instead of the output voltage value VH. Here, the carrier frequency is a frequency indicating the frequency of the drive signal applied to the plurality of booster circuits.

  Note that the multiphase boost converter to be controlled in the control method of the multiphase boost converter according to the second embodiment may be the same as the multiphase boost converter 11 according to the first embodiment, and output from the multiphase boost converter 11. The thing remove | excluding the voltage detection part 14 may be sufficient. The carrier frequency used in the control method of the multiphase boost converter according to the second embodiment is the frequency of the drive signal output by the control unit 12 and is the frequency that the control unit 12 grasps.

  FIG. 6 is a flowchart for explaining the control procedure of the multiphase boost converter according to the second embodiment. As shown in FIG. 6, in the control method of the multiphase boost converter according to the second embodiment, steps S1 and S2 in the flowchart of the control method according to the first embodiment shown in FIG. 3 are replaced with steps S11 and S12. Is.

  In step S11, the control unit 12 reads the input current value Iin from the current detection unit 13, and stores the frequency of the drive signal output by itself as the carrier frequency. In step S12, the control unit 12 selects one map corresponding to the carrier frequency from the map group, and refers to the selected map. The control unit 12 performs a map selection step of selecting one of the maps based on the current carrier frequency of the multiphase boost converter in steps S11 and S12.

  Subsequent steps S3 to S5 are the same as those in the control method of the multiphase boost converter 11 according to the first embodiment, and thus the description thereof is omitted.

  From the above description, in the control method of the multiphase boost converter according to the second embodiment, a map is provided for each carrier frequency, a map corresponding to the carrier frequency is selected, and the number of drive phases is determined based on the selected map. Thereby, the multiphase boost converter according to the second embodiment can prevent a decrease in conversion efficiency due to a difference in carrier frequency.

Embodiment 3
In the third embodiment, another embodiment of a map creation method will be described. In the control method of the multiphase boost converter according to the third embodiment, the map group refers to a map group including a map provided for each combination of the output voltage value VH and the carrier frequency. The multiphase boost converter to be controlled in the control method of the multiphase boost converter according to the third embodiment is the same as the multiphase boost converter 11 according to the first embodiment.

  FIG. 7 is a flowchart for explaining the control procedure of the multiphase boost converter according to the third embodiment. As shown in FIG. 7, in the control method of the multiphase boost converter according to the third embodiment, steps S1 and S2 in the flowchart of the control method according to the first embodiment shown in FIG. 3 are replaced with steps S21 and S22. Is.

  In step S21, the control unit 12 reads the input current value Iin and the output voltage value VH from the current detection unit 13 and the output voltage detection unit 14, and stores the frequency of the drive signal output by itself as the carrier frequency. In step S22, the control unit 12 selects one map corresponding to the combination of the output voltage value VH and the carrier frequency from the map group, and refers to the selected map. The controller 12 performs a map selection step of selecting one of the maps based on the current output voltage value VH and the carrier frequency of the multiphase boost converter in steps S21 and S22.

  Subsequent steps S3 to S5 are the same as those in the control method of the multiphase boost converter 11 according to the first embodiment, and thus the description thereof is omitted.

  From the above description, in the control method of the multiphase boost converter according to the third embodiment, a map is provided for each combination of the output voltage value VH and the carrier frequency, and the map corresponds to the combination of the output voltage value VH and the carrier frequency. A map is selected, and the number of drive phases is determined based on the selected map. Thereby, the multiphase boost converter according to the third embodiment can prevent a decrease in conversion efficiency due to a difference in output voltage value VH and a difference in carrier frequency.

  In the above description, the invention made by the present inventor has been specifically described based on the embodiments. However, the present invention is not limited to the embodiments already described, and various modifications can be made without departing from the scope of the invention. It goes without saying that changes are possible.

DESCRIPTION OF SYMBOLS 1 System 10 Input power supply 11 Polyphase boost converter 12 Control part 13 Current detection part 14 Output voltage detection part 20 Power control unit

Claims (2)

A control method of a multi-phase boost converter having a plurality of boost circuits connected in parallel to an output terminal from which an output voltage supplied to a load circuit is output,
A map preparation step of preparing in advance a map showing the correspondence between the number of drive phases in which the power efficiency of the multiphase boost converter is highest and the input current to the multiphase boost converter for each different output voltage value;
A map selection step of detecting the output voltage of the multi-phase boost converter and selecting one of the maps based on the detected output voltage;
A drive phase number selection step of detecting the input current of the multi-phase boost converter and selecting the number of drive phases with the highest power efficiency in the detected input current based on the selected map;
A control method for a multi-phase boost converter. A control method of a multi-phase boost converter having a plurality of boost circuits connected in parallel to an output terminal from which an output voltage supplied to a load circuit is output,
Correspondence between the number of drive phases in which the power efficiency of the multi-phase boost converter is highest for each of the different carrier frequencies and the input current to the multi-phase boost converter with the frequency of the drive signal applied to the plurality of boost circuits as the carrier frequency A map preparation step for preparing a map indicating
A map selection step of selecting one of the maps based on the current carrier frequency of the multi-phase boost converter;
A drive phase number selection step of detecting the input current of the multi-phase boost converter and selecting the number of drive phases with the highest power efficiency in the detected input current based on the selected map;
A control method for a multi-phase boost converter.

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