power supply unit

Abstract

The present application relates to a power supply unit, provided with a power supply and a converter, the converter performing at least one selected from a group consisting of step-up and step-down of an output voltage from the power supply, the converter being provided with n-phase reactors whose coils are magnetically coupled to each other, n-phase switches, and a control unit, the control unit controlling duty ratios of the n-phase switches and monitoring current values flowing through the coils of the n-phase reactors, the control unit being configured to perform phase switching control of switching from the same phase to different phases when the n-phase switches are driven at the same phase or switching from different phases to the same phase when the n-phase switches are driven at different phases, when it is determined that a prescribed operation condition is satisfied.

Description

Technical Field

[0001] This disclosure relates to power supply units. Background Technology

[0002] Various studies have been conducted on the converters included in the power units of systems used in vehicles such as fuel cell electric vehicles (FCEVs). DC / DC converters used in various electronic devices often employ circuits composed of reactors, switches, diodes, and capacitors. The DC / DC converter controls the increase or decrease of the current flowing through the reactor by switching on / off signals.

[0003] For example, Japanese Patent Application Publication No. 2020-088971 discloses a technique that can suppress unexpected large currents at the output of a boost converter.

[0004] In addition, Japanese Patent Application Publication No. 2017-143708 discloses a semiconductor device that can detect the occurrence of an abnormality caused by an abnormality on the load side when a power supply circuit supplies power to a load.

[0005] In addition, Japanese Patent Application Publication No. 2014-212587 discloses a converter device that controls the current flow to the reactor in a continuous mode and in a discontinuous mode in which the current flows to the reactor intermittently, and controls the current flow to the reactor by means of the duty cycle.

[0006] In addition, Japanese Patent Application Publication No. 2015-019448 discloses a converter device for setting the duty cycle in reactor current control using a correction value reflecting the historical difference between the target output and the actual output of the reactor and the inductance of the reactor.

[0007] The converter exhibits a discontinuous mode that is insensitive to increases in the duty cycle reactor current and a continuous mode that is sensitive to increases in the reactor current. If the converter is not controlled with an appropriate duty cycle in each mode, electrical errors will occur. In the prior art, overcurrent or undercurrent occurs in the boundary region between the continuous and discontinuous modes of the converter. This can lead to overcharging and discharging of the battery, torque fluctuations in the vehicle, and other issues.

[0008] On the other hand, for the miniaturization of the converter, the introduction of a magnetically coupled converter with a magnetically coupled reactor that magnetically couples multiple coils on the same core can be considered as an option. In a magnetically coupled converter, output current ripple is reduced by mitigating magnetic saturation of the reactor core, so the magnetically coupled coils are generally switched alternately at equal intervals (opposite phase) with the same duty cycle and phase difference.

[0009] However, in discontinuous operation, including periods when the current flowing through the coil is zero due to low load, the current waveform of the magnetically coupled reactor becomes very complex if it is controlled in reverse phase, and there is also the possibility of reverse current, making current control difficult. Summary of the Invention

[0010] This disclosure was made in view of the above-mentioned actual situation, and provides a power supply unit capable of suppressing the occurrence of overcurrent and undercurrent.

[0011] The power supply unit disclosed herein is characterized by having a power supply and a converter.

[0012] The converter described above is configured to perform at least one selection from the group consisting of boost and buck converters of the output voltage of the power supply described above.

[0013] The aforementioned converter includes a reactor with n (n being an integer of 2 or more) phases of coils magnetically coupled to each other, n phase switches connected to the aforementioned coils respectively, and a control unit.

[0014] The aforementioned control unit controls the duty cycle of the aforementioned switches in the n-phase phase.

[0015] The aforementioned control unit monitors the current value flowing through the aforementioned coils of phase n.

[0016] The control unit is configured to perform phase switching control when the following operating condition (1) is met: switching from the same phase to a different phase when the switches of the n phases are driven in the same phase respectively, and switching from a different phase to the same phase when the switches of the n phases are driven in different phases respectively.

[0017] Operating conditions (1): In the relationship between the input voltage and output voltage of the converter and the current flowing through the coil, when the input voltage and output voltage of the converter are respectively a predetermined voltage value, it becomes a discontinuous mode in one cycle of the duty cycle control when the switches of the n phases are driven with the same phase, and a continuous mode in one cycle of the duty cycle control when the switches of the n phases are driven with different phases, without a period in one cycle of the duty cycle control, where the current flowing through the coil is zero.

[0018] In the power supply unit of this disclosure, the control unit can be configured to pre-store a data set, which represents the relationship between the input voltage and output voltage of the converter and the current flowing through the coil when the operating condition (1) is met.

[0019] The control unit is configured to refer to the data set and determine whether the above operating conditions (1) are met based on the input voltage and output voltage of the converter and the current value flowing through the coil of phase n.

[0020] In the power supply unit of this disclosure, the control unit may be configured to perform the phase switching control when the current value flowing through the coil is consistent with the average current value of the coil, when it is determined that the above-mentioned operating condition (1) is met.

[0021] In the power supply unit of this disclosure, the control unit may be configured such that, in the phase switching control, if the current value flowing through the coil is rising before the phase switching from the same phase to a different phase, the phase switching occurs in such a way that the current value flowing through the coil rises after the phase switching from the same phase to a different phase.

[0022] In the power supply unit of this disclosure, the control unit may be configured such that, in the phase switching control, if the current value flowing through the coil is decreasing before the phase switching from the same phase to a different phase, the phase switching occurs in such a way that the current value flowing through the coil decreases after the phase switching from the same phase to a different phase.

[0023] In the power supply unit of this disclosure, the aforementioned different phases can be a phase difference of (360 / n)°.

[0024] In the power supply unit of this disclosure, the aforementioned n phases can be two phases.

[0025] The different phases mentioned above represent a phase difference of 180°.

[0026] In the power supply unit of this disclosure, the power source can be a fuel cell.

[0027] In the power supply unit of this disclosure, the control unit can be configured to perform a phase switch from a different phase to the same phase when it is determined that the current flowing through the coil is below a predetermined first switching threshold during the phase switching control.

[0028] The control unit is configured to perform a phase switch from the same phase to a different phase when it is determined that the current value flowing through the coil is greater than or equal to a predetermined second switching threshold that is greater than a predetermined first switching threshold in the phase switching control.

[0029] The power supply unit according to this disclosure can suppress the occurrence of overcurrent and insufficient current. Attached Figure Description

[0030] Hereinafter, the features, advantages, technical and industrial importance of exemplary embodiments of the present invention will be described with reference to the accompanying drawings, in which the same reference numerals denote the same constituent elements, wherein:

[0031] Figure 1This is a diagram illustrating an example of the circuit structure of a power supply unit with a boost converter and peripheral components.

[0032] Figure 2 This is a diagram showing an example of the current waveform when the current flowing through the coil of the reactor in a boost converter is in continuous mode.

[0033] Figure 3 This is a diagram showing an example of the current waveform when the current flowing through the coil of the reactor in a boost converter is in a discontinuous mode.

[0034] Figure 4 This is a diagram illustrating an example of the current waveform when the two phases of a magnetically coupled reactor with coils of phases U and V, which drive a boost converter in the same phase, are switched (in-phase duty cycle control).

[0035] Figure 5 This is a diagram illustrating an example of the current waveform when the two phases of a magnetically coupled reactor with coils of phases U and V, driven in opposite phases respectively, are switched (in reverse phase duty cycle control).

[0036] Figure 6 This is a graph showing the relationship between the input voltage of the converter and the current flowing through the coil when the output voltage of the converter with a magnetically coupled reactor having two-phase coils is kept constant.

[0037] Figure 7 yes Figure 6 The diagram shown illustrates the switching threshold.

[0038] Figure 8 This is a graph illustrating an example of the relationship between time and reactor current in a converter with a magnetically coupled reactor having two-phase coils, where phase switching control is performed from in-phase drive to out-of-phase drive when the current value flowing through the coil (reactor current value) is inconsistent with the average current value of the reactor.

[0039] Figure 9 This is another example of the relationship between time and reactor current in a converter with a magnetically coupled reactor having two-phase coils, where phase switching control is performed from in-phase drive to out-of-phase drive when the current value flowing through the coil (reactor current value) is inconsistent with the average current value of the reactor.

[0040] Figure 10This is a diagram illustrating an example of the relationship between time and reactor current in a converter with a magnetically coupled reactor having two-phase coils, where phase switching control is performed from in-phase drive to anti-phase drive when the current flowing through the coil matches the average current of the reactor, and then phase switching control is performed from anti-phase drive to in-phase drive when the current flowing through the coil matches the average current of the reactor.

[0041] Figure 11 This is a graph illustrating an example of the relationship between time and reactor current in a converter with a magnetically coupled reactor having two-phase coils, where the current flowing through the coil is rising before the phase switch from in-phase to out-of-phase, the phase switch proceeds from in-phase to out-of-phase, and then the phase switch proceeds in such a way that the current flowing through the coil decreases after the phase switch proceeds from out-of-phase to in-phase.

[0042] Figure 12 This is another example of the relationship between time and reactor current in a converter with a magnetically coupled reactor having two-phase coils, where the current flowing through the coil is decreasing before the phase switch from in-phase to out-of-phase, and then the phase switch occurs in such a way that the current flowing through the coil increases after the phase switch from out-of-phase to in-phase.

[0043] Figure 13 This is a diagram illustrating an example of the relationship between time and reactor current in a converter with a magnetically coupled reactor having two-phase coils, where the current flowing through the coil is rising before the phase switch from in-phase to out-of-phase, the phase is switched from in-phase to out-of-phase, and then the phase is switched again in such a way that the current flowing through the coil rises after the phase switch from out-of-phase to in-phase.

[0044] Figure 14 This is a diagram illustrating an example of the relationship between time and reactor current in a converter with a magnetically coupled reactor having two-phase coils, where the current flowing through the coil is decreasing before the phase switch from in-phase to out-of-phase, and the phase switch occurs in such a way that the current flowing through the coil decreases after the phase switch from out-of-phase to in-phase.

[0045] Figure 15 This is a flowchart illustrating an example of phase switching control, which is a typical example of the present disclosure.

[0046] Figure 16 This is a flowchart illustrating an example of phase switching control, representing a specific example of the present disclosure.

[0047] Figure 17This is a flowchart illustrating an example of phase switching control in a variation of this disclosure, 1.

[0048] Figure 18 This is a flowchart illustrating an example of phase switching control in Modification 2 of this disclosure. Detailed Implementation

[0049] The power supply unit disclosed herein is characterized by having a power supply and a converter.

[0050] The converter described above is configured to perform at least one selection from the group consisting of boost and buck converters of the output voltage of the power supply described above.

[0051] The aforementioned converter includes a reactor with n (n being an integer of 2 or more) phases of coils magnetically coupled to each other, n phase switches connected to the aforementioned coils respectively, and a control unit.

[0052] The aforementioned control unit controls the duty cycle of the aforementioned switches in the n-phase phase.

[0053] The aforementioned control unit monitors the current value flowing through the aforementioned coils of phase n.

[0054] The control unit is configured to perform phase switching control when the following operating condition (1) is met: switching from the same phase to a different phase when the switches of the n phases are driven in the same phase respectively, and switching from a different phase to the same phase when the switches of the n phases are driven in different phases respectively.

[0055] Operating conditions (1): In the relationship between the input voltage and output voltage of the converter and the current flowing through the coil, when the input voltage and output voltage of the converter are respectively a predetermined voltage value, it becomes a discontinuous mode in one cycle of the duty cycle control when the switches of the n phases are driven with the same phase, and a continuous mode in one cycle of the duty cycle control when the switches of the n phases are driven with different phases, without a period in one cycle of the duty cycle control, where the current flowing through the coil is zero.

[0056] In the aforementioned Japanese Patent Application Publication No. 2020-088971, the current operating mode (continuous or discontinuous) is determined by the smaller of a feedforward term for discontinuous mode calculated based on the inductance of the reactor, the carrier frequency, the input voltage of the converter, and the output voltage of the converter, and a feedforward term for continuous mode calculated based on the input voltage of the converter and the output voltage of the converter. However, there are concerns that the control unit may be unable to accurately identify the boundary between continuous and discontinuous modes in cases where the inductance of the reactor deviates from the target value due to product deviations, or where there are measurement deviations in sensor values ​​such as the input voltage and output voltage of the converter.

[0057] That is, the technology mentioned in Japanese Patent Application Publication No. 2020-088971 is "to find the moment when the circuit operation switches from discontinuous mode to continuous mode or from continuous mode to discontinuous mode, and to perform corresponding control", and the control is "passive" relative to the circuit operation.

[0058] Circuit operation is a physical phenomenon, so it is continuous (there are no gaps in time). On the other hand, control units such as microcomputers operate only within specific time periods, so control is intermittent (there are gaps in time).

[0059] Therefore, even with the use of any high-speed control unit and control methods, the following situation will inevitably occur in principle: although it is in discontinuous mode at a certain moment, by the time the control unit recognizes it in the next moment, it has already switched to continuous mode and cannot achieve pattern recognition and tracking. In this case, at some point during the period, the circuit switches from discontinuous mode to continuous mode, but the control unit cannot recognize this situation, and the control unit is trapped in a situation where it wants to control using the duty cycle used in discontinuous mode.

[0060] Although the circuit is in continuous mode, the control unit mistakenly interprets it as discontinuous mode and sets the duty cycle too high, resulting in overcurrent. On the other hand, although the circuit is in discontinuous mode, the control unit mistakenly interprets it as continuous mode and sets the duty cycle too low, resulting in insufficient current. As a result, situations such as overcharging and discharging of the battery and unwanted torque fluctuations in the vehicle may occur.

[0061] The circuitry of a magnetically coupled converter exhibits an insensitive region where the duty current increases disproportionately under low load. To avoid this insensitive region, the duty cycle is controlled with the same phase under low load and with a different phase under high load.

[0062] In this disclosure, since the circuit operation of the converter is determined by control, the switching between continuous mode and discontinuous mode can be actively and accurately implemented. Therefore, the switching between continuous mode and discontinuous mode will not occur over time, and there will be no duty cycle that is mismatched with the operation of the circuit. The generation of overcurrent and insufficient current can be suppressed.

[0063] Figure 1 This is a diagram illustrating an example of the circuit structure of a power supply unit with a boost converter and peripheral components.

[0064] Figure 1The power supply unit shown is, for example, mounted in a vehicle, and connected to the vehicle's drive motor as an external load 50 via an inverter. Additionally, although not shown, a battery can be connected in parallel with the fuel cell 10 and the boost converter 20. The output power of the fuel cell 10 is boosted by the boost converter 20, and then converted from DC to AC by the inverter before being supplied to the motor.

[0065] The boost converter 20 has a six-phase boost circuit connected in parallel. Figure 1 The diagram shows the structure of a boost circuit with 6 phases, but the number of phases is not particularly limited. The boost circuit includes a reactor 21, a current sensor 22, a switch 23, a diode 24, and a capacitor 25. The boost circuit may also include an input voltage sensor and an output voltage sensor.

[0066] In the 6-phase boost circuit, each pair of phases can share the core of one reactor 21 and be magnetically coupled to each other. In each boost circuit, if switch 23 is turned on, the current flowing through reactor 21 increases; if switch 23 is turned off, the current flowing through reactor 21 decreases, and remains zero when the current reaches zero. Current sensor 22 obtains the current value flowing through reactor 21.

[0067] A control unit (not shown) controls the on / off state of switch 23 to control the boost ratio in converter 20 and the output current value from fuel cell 10.

[0068] The output power of fuel cell 10 varies significantly depending on the vehicle's requirements (speed, acceleration, load, and road gradient, etc.), and the output current also varies significantly accordingly. When the output current of fuel cell 10 is high, if this current flows to a single boost circuit, heat generation increases and the power conversion efficiency of boost converter 20 decreases. Furthermore, when only a small current flows to a boost circuit capable of handling large currents, energy loss also increases, and the power conversion efficiency of boost converter 20 decreases. Therefore, boost converter 20 has a multi-phase boost circuit (in... Figure 1 (In the example shown, there are 6 phases). The boost converter 20 switches the number of phases driven according to the output current value of the fuel cell 10. For example, it drives with 2 phases when the output current value of the fuel cell 10 is 0-150A, with 4 phases when it is 150-300A, and with 6 phases when it is 300-600A. The boost circuit has different efficiencies depending on the flowing current, and by changing the number of driving phases, it can operate at the optimal efficiency in each current range.

[0069] The power supply unit includes a power supply and a converter.

[0070] The power supply unit disclosed herein can also be a system used in vehicles such as fuel cell vehicles.

[0071] The power source can be a fuel cell or a storage battery, etc.

[0072] When the power source is a fuel cell, the power unit of this disclosure can be a fuel cell system.

[0073] A fuel cell can consist of a single cell or a fuel cell stack consisting of multiple stacked cells.

[0074] The converter selects at least one from the group consisting of boost and buck output voltages from the power supply. The converter can be a boost converter, a buck converter, or a buck-boost converter.

[0075] The converter can also be a DC / DC converter.

[0076] The converter includes an inductor with n (n is an integer of 2 or more) phases of coils magnetically coupled together, n phase switches connected to the coils respectively, and a control unit. The converter may include diodes, current sensors, voltage sensors, optocouplers, and capacitors, etc.

[0077] A reactor has a coil and a core.

[0078] The core can be wound with n (n is an integer greater than or equal to 2) phases of coil. N can be 2 or more, and there is no specific upper limit. It can be less than 10, less than 5, less than 4, or less than 3.

[0079] The reactor's core and coil can be the same as those used in conventionally known converters.

[0080] In this disclosure, a reactor having a core with a single-phase coil wound around it is referred to as a non-magnetically coupled reactor. In this disclosure, a converter equipped with a non-magnetically coupled reactor is referred to as a non-magnetically coupled converter.

[0081] In this disclosure, a reactor having a core with two or more independent coils wound around it is referred to as a magnetically coupled reactor. In this disclosure, a converter equipped with a magnetically coupled reactor is referred to as a magnetically coupled converter.

[0082] In this disclosure, an independent coil refers to a coil having one or more helical portions and two terminal portions.

[0083] The switch (switching element) consists of a transistor and a protective diode. The transistor is an npn type transistor, such as an IGBT (Insulated Gate Bipolar Transistor), a power MOS (Metal Oxide Semiconductor) transistor, or a power bipolar transistor. The diode can be one used in conventionally known converters.

[0084] The current sensor is not particularly limited as long as it can obtain the current value I flowing in the coil of the reactor (in the case of a value referred to as the reactor current value), and conventionally known ammeters can be used. Furthermore, in this disclosure, the average reactor current refers to the average current flowing through the coil during one cycle of duty cycle control.

[0085] A voltage sensor is not particularly limited as long as it can obtain the input voltage from the power supply output to the converter; conventionally known voltmeters and the like can be used.

[0086] The control unit can also be an electronic control unit (ECU) or a microcomputer. An ECU consists of a CPU (Central Processing Unit), memory, and input / output buffers.

[0087] The control unit detects the current value flowing to the n-phase coil of the reactor based on the signal from the current sensor, and monitors the current value flowing in the n-phase coil.

[0088] The control unit controls the on / off state of the n-phase switches and controls the duty cycle of the n-phase switches.

[0089] The control unit can operate the magnetically coupled n-phase switches at a constant frequency. The control unit can control the duty cycle of the n-phase switches by periodically switching the on and off commands to the switches. The control unit can operate each of the n-phase switches with the same duty cycle. The control unit can also operate each of the n-phase switches with slightly different duty cycles.

[0090] In the case of duty cycles for in-phase driving and duty cycles for different phase driving, the duty cycles are usually set in a way that the duty cycles are different from each other.

[0091] As for the duty cycle when driving in the same phase and the duty cycle when driving in different phases, as long as the duty cycles are different, there is no particular limitation on each duty cycle. They can be appropriately set according to the output requests from the load.

[0092] In a boost converter, the voltage is boosted by repeatedly controlling the duty cycle of the energy storage and release in the reactor over one cycle. The duty cycle determines the proportion of the time during which the switching element is open and energy is stored in the reactor within one cycle of the boost operation. Let T be the cycle of the duty cycle control for the boost operation in the boost converter, and let T be the period during which the switching element is on. ON The shutdown period is set to T. OFF At that time, the duty cycle D is expressed as D = T ON / T.

[0093] In this disclosure, one cycle of duty cycle control refers to the switching cycle of the switch. The switching cycle of the switch refers to the period from the moment the switch switches from open to closed until the moment the switch switches from open to closed again.

[0094] [Typical example]

[0095] When the following operating condition (1) is determined to be met, the control unit performs phase switching control, which switches from the same phase to different phases when the switches of n phases are driven with the same phase respectively, and switches from different phases to the same phase when the switches of n phases are driven with different phases respectively.

[0096] Operating conditions (1): When the input voltage and output voltage of the converter are respectively specified voltage values ​​in the relationship between the input voltage and output voltage of the converter and the current value flowing through the coil, the converter becomes a discontinuous mode with a period of zero current value flowing through the coil in one cycle of the duty cycle control when the switches of the n phases are driven with the same phase, and becomes a continuous mode without a period of zero current value flowing through the coil in one cycle of the duty cycle control when the switches of the n phases are driven with different phases.

[0097] Whether the above operating conditions (1) are met can be determined based on the input voltage and the current value flowing through the coil (reactor current value) for the set output voltage.

[0098] The specified input voltage value is determined based on the output from the power supply.

[0099] The specified voltage value of the output voltage is appropriately set according to the request from the vehicle's motor or other loads.

[0100] The control unit can repeatedly determine whether the above operating conditions (1) are met, or it can do so at a specified time, or it can do so every specified cycle of the duty cycle (e.g., every 4 to 10 cycles).

[0101] When the n-phase switches are operated with different phases, the control unit can make the n-phase switches operate with a phase difference of (360 / n)°.

[0102] When the switch is two-phase and the two-phase switches operate with different phases, the control unit can make the two-phase switches operate with a phase difference of 30° to 180°. From the viewpoint of improving power conversion efficiency, it is possible to operate with a phase difference of 180°, i.e., in opposite phase. In the case of operating in opposite phase, a phase error can be generated in the range of -5° to +5°.

[0103] [Explanation of continuous mode and discontinuous mode]

[0104] Figure 2 This is a diagram showing an example of the current waveform when the current flowing through the coil of the reactor in a boost converter is in continuous mode.

[0105] Figure 3 This is a diagram showing an example of the current waveform when the current flowing through the coil of the reactor in a boost converter is in a discontinuous mode.

[0106] like Figure 2 As shown, the current flowing through the reactor coil of the boost converter (reactor current) forms a triangular wave with the switching action, and the center value of the triangular wave is the average reactor current (hereinafter referred to as the average current). Here, if the duty cycle is reduced to gradually decrease the average current, the lowest point of the triangular wave reaches 0A. If the average current is further reduced from here, since the boost converter is a unidirectional circuit, as... Figure 3 As shown, this is the period during which the reactor current begins to be zero. The operation of the converter's duty cycle during a period when the current flowing through the reactor coil is zero is called discontinuous mode, while the operation during a period when the current flowing through the reactor coil is not zero is called continuous mode.

[0107] [Explanation of in-phase drive and out-of-phase drive]

[0108] Figure 4 This is a diagram illustrating an example of the current waveform when the two phases of a magnetically coupled reactor with coils of phases U and V, which drive a boost converter in the same phase, are switched (in-phase duty cycle control).

[0109] If the switches of phases U and V are simultaneously turned on / off with the same duty cycle, it is called in-phase drive.

[0110] Figure 5This is a diagram illustrating an example of the current waveform when the two phases of a magnetically coupled reactor with coils of phases U and V, driven in opposite phases respectively, are switched (in reverse phase duty cycle control).

[0111] If the switches of phases U and V are switched on / off with the same duty cycle but with the switching cycle (drive cycle) staggered by half a cycle, this is called reverse-phase drive. In reverse-phase drive, a reactor current with a smaller amplitude can be obtained compared to in-phase drive.

[0112] The control unit may also pre-store a data set showing the relationship between the input voltage and output voltage of the converter and the current value flowing through the coil when the above operating conditions (1) are met, and determine whether the above operating conditions (1) are met by referring to the data set and based on the input voltage and output voltage of the converter and the current value flowing through the coil in the n-phase.

[0113] Operating conditions that are discontinuous in in-phase drive and continuous in different-phase drive are, for example, operating conditions given in a boost converter by the following formulas (1) to (2), such as Figure 6 As shown. These formulas (1) to (2) can be stored in advance. Figure 6 The data shown is used as a data group. In the case of buck converters and buck-boost converters, the same data group as in the case of boost converters can also be pre-stored.

[0114] Figure 6 This is a graph showing the relationship between the input voltage of the converter and the current flowing through the coil when the output voltage of the converter equipped with a magnetically coupled reactor having two-phase coils is kept constant. Figure 6 In the middle, V L Indicates the input voltage (voltage before boost), I L This represents the average current of the reactor.

[0115] Figure 6 The meanings of the regions A through C shown are as follows.

[0116] A: The region is a discontinuous mode under either in-phase or out-of-phase driving conditions.

[0117] B: Switchable region (region that operates in continuous mode under anti-phase drive and discontinuous mode under in-phase drive).

[0118] C: Regions that are continuous mode under either in-phase or out-of-phase driving conditions.

[0119] Figure 6 The switchable region of B shown is the region that satisfies operating condition (1).

[0120] Therefore, in a typical example of this disclosure, phase switching control can be performed whenever a switchable region of B is entered.

[0121] [Equation 1]

[0122]

[0123] [Equation 2]

[0124]

[0125] Equation (1) is an inequality representing the relationship between the input and output voltages of a boost converter and the current flowing through the coil when the boost ratio is 2 or higher. In the inequality of equation (1), the left side is... Figure 6 The current curve for the lower limit of the region shown by the dashed line when the boost ratio is above 2 is shown on the right. Figure 6 The current curve for the upper limit of the region when the boost ratio is 2 or higher is shown by a solid line.

[0126] Equation (2) is an inequality representing the relationship between the input and output voltages of the boost converter and the current flowing through the coil when the boost ratio is less than 2. In the inequality of equation (2), the left side is... Figure 6 The current curve for the lower limit of the region where the boost ratio is less than 2 is shown by the dashed line. The right side is... Figure 6 The current curve for the upper limit of the region where the boost ratio is less than 2 is shown by the solid line.

[0127] In equations (1) to (2), V L Indicates the input voltage (voltage before boost), I L V represents the average current of the reactor. H The output voltage (boosted voltage) is represented by M, the mutual inductance of the reactor is represented by L, and the switching cycle is represented by T.

[0128] [Specific example]

[0129] In phase switching control, the control unit can perform phase switching from different phases to the same phase when it determines that the current flowing through the coil is below a predetermined first switching threshold, and can perform phase switching from the same phase to different phases when it determines that the current flowing through the coil is above a predetermined second switching threshold that is greater than the predetermined first switching threshold.

[0130] Figure 7 yes Figure 6 The diagram shown illustrates the switching threshold.

[0131] For example, it can be like Figure 7The calculation shown above will determine the switchable region, bounded by the upper and lower switching limits, relative to which input voltage V. L The values ​​are divided into three equal parts. The side that is closer to the lower switching limit is set as the first switching threshold, and the side that is closer to the upper switching limit is set as the second switching threshold.

[0132] Furthermore, it can be determined as the average current I of the reactor. L When the first switching threshold is below, a phase switch is performed from a different phase to the same phase.

[0133] On the other hand, it can be determined as the average current I of the reactor. L Phase switching from the same phase to a different phase occurs when the second switching threshold is exceeded.

[0134] With these settings, phase switching no longer occurs frequently, and it is also robust to product deviations.

[0135] It can be used for any output voltage V H The first switching threshold and the second switching threshold, as described above, are pre-calculated for any switching period T and pre-stored as a data set.

[0136] In the above Figure 7 In the example shown, the difference between the first and second switching thresholds is one-third of the difference between the upper and lower switching thresholds. However, it can also be greater than one-third of the difference between the upper and lower switching thresholds; for example, it could be one-half or two-thirds of the difference. Alternatively, the first switching threshold can be used as the lower switching threshold, and the second switching threshold can be used as the upper switching threshold. When the difference between the upper and lower switching thresholds is large, phase switching is less likely to occur frequently.

[0137] In the above Figure 7 In the example shown, the difference between the upper switching threshold and the second switching threshold, and the difference between the first switching threshold and the lower switching threshold, are one-third of the difference between the upper and lower switching thresholds. However, as long as the difference between the first and second switching thresholds is within a range, i.e., the difference between the upper and lower switching thresholds is less than one-half, it is acceptable; it can be greater than one-third, for example, two-fifths or three-sevenths. If the difference between the upper and second switching thresholds and the difference between the first and lower switching thresholds is made as large as possible within the range less than one-half of the difference between the upper and lower switching thresholds, then even if the upper switching threshold decreases or the lower switching threshold increases due to errors in the output voltage sensor, input voltage sensor, reactor self-inductance L, reactor mutual inductance M, etc., phase switching control can still be implemented.

[0138] Furthermore, in the above Figure 7 In the example shown, the difference between the upper switching limit and the second switching threshold is equal to the difference between the first switching threshold and the lower switching limit, but the difference between the upper switching limit and the second switching threshold can also be large. In this case, the overall power conversion efficiency can be improved because the drive time under the opposite phase with good power conversion efficiency can be extended.

[0139] [Variation Example 1]

[0140] When the above operating condition (1) is determined to be met, the control unit may perform the above phase switching control when the current value flowing through the coil is consistent with the average current value of the coil (average current value of the reactor).

[0141] In Modification 1 of this disclosure, since the average current flowing in the coil of the reactor does not change before and after switching between different phases and the same phase (= no output change), the impact on the movement of vehicles, etc., can be reduced.

[0142] Figure 8 This is a graph illustrating an example of the relationship between time and reactor current in a converter with a magnetically coupled reactor having two-phase coils, where phase switching control is performed from in-phase drive to out-of-phase drive when the current value flowing through the coil (reactor current value) is inconsistent with the average current value of the reactor.

[0143] Figure 9 This is another example of the relationship between time and reactor current in a converter with a magnetically coupled reactor having two-phase coils, where phase switching control is performed from in-phase drive to out-of-phase drive when the current value flowing through the coil (reactor current value) is inconsistent with the average current value of the reactor.

[0144] like Figures 8-9 As shown, in the above typical and specific examples, if the switching timing is off, the current values ​​flowing in the coils of each phase will be as follows: Figures 8-9 The gaps between E and F change as shown in the diagram.

[0145] This means that the output from the power source is erratic, which could cause overcharging and over-discharging of the battery if the output exceeds the allowable value, or cause changes in vehicle behavior due to torque variations in the drive motor.

[0146] Figure 10This is a diagram illustrating an example of the relationship between time and reactor current in a converter with a magnetically coupled reactor having two-phase coils, where phase switching control is performed from in-phase drive to anti-phase drive when the current flowing through the coil matches the average current of the reactor, and then phase switching control is performed from anti-phase drive to in-phase drive when the current flowing through the coil matches the average current of the reactor.

[0147] like Figure 10 As shown by arrow 1, when the current flowing through the coil matches the average current of the reactor, phase switching control is performed from in-phase drive to anti-phase drive. Similarly, as shown by arrow 2, when the current flowing through the coil matches the average current of the reactor, phase switching control is performed from anti-phase drive to in-phase drive. This suppresses changes in the average current of the reactor within the range of in-phase operation, including both the anti-phase operation period and the in-phase operation period before and after that anti-phase operation period. Since the average current of the reactor does not change before and after the phase switch (i.e., no change in power output), it is difficult to affect the movement of vehicles, etc.

[0148] [Variation Example 2]

[0149] In phase switching control, if the current value flowing through the coil is rising before the phase switching from the same phase to a different phase, the control unit can switch the phase in such a way that the current value flowing through the coil rises after the phase switching from the same phase to a different phase.

[0150] On the other hand, in phase switching control, if the current value flowing through the coil is decreasing before the phase switching from the same phase to a different phase, the control unit can switch the phase in such a way that the current value flowing through the coil decreases after the phase switching from the same phase to a different phase.

[0151] In Modification 2 of this disclosure, the variation in the average current flowing through the reactor coil can be suppressed within a range including operating periods under different phases and operating periods under the same phase before and after those operating periods. Since the average current flowing through the reactor coil does not change before and after the phase switch (i.e., no output change), the impact on the movement of vehicles, etc., can be reduced.

[0152] Figure 11This is a graph illustrating an example of the relationship between time and reactor current in a converter with a magnetically coupled reactor having two-phase coils, where the current flowing through the coil is rising before the phase switch from in-phase to out-of-phase, and then the phase switch occurs in such a way that the current flowing through the coil decreases after the phase switch from out-of-phase to in-phase.

[0153] like Figure 11 As shown in case G, the average reactor current during one cycle of the immediate preceding and immediate following in-phase drive of the anti-phase drive is less than the average reactor current during one cycle of the in-phase drive immediately preceding the anti-phase drive and the average reactor current during one cycle of the in-phase drive immediately following the anti-phase drive, resulting in reactor current disturbance due to phase switching.

[0154] Figure 12 This is another example of the relationship between time and reactor current in a converter with a magnetically coupled reactor having two-phase coils, where the current flowing through the coil is decreasing before the phase switch from in-phase to out-of-phase, and then the phase switch occurs in such a way that the current flowing through the coil increases after the phase switch from out-of-phase to in-phase.

[0155] like Figure 12 As shown in case H, the average reactor current during one cycle of the immediate preceding and immediate following in-phase drive of the anti-phase drive is greater than the average reactor current during one cycle of the in-phase drive immediately preceding the anti-phase drive and the in-phase drive immediately following the anti-phase drive, resulting in reactor current disturbance due to phase switching.

[0156] like Figures 11-12 As shown, in the above typical example, specific example, and modified example 1, if the timing of the phase switching is different, the current values ​​flowing in the coils of each phase are as follows: Figures 11-12 The situation shown changes in the same way as G and H.

[0157] Situations G and H are similar to situations E and F, meaning that the output from the power supply is disordered, and there is a possibility that if the output exceeds the allowable value, it will cause overcharging and discharging of the battery, or changes in vehicle behavior due to torque variations of the drive motor.

[0158] Figure 13This is a diagram illustrating an example of the relationship between time and reactor current in a converter with a magnetically coupled reactor having two-phase coils, where the current flowing through the coil is rising before the phase switch from in-phase to out-of-phase, the phase is switched from in-phase to out-of-phase, and then the phase is switched again in such a way that the current flowing through the coil rises after the phase switch from out-of-phase to in-phase.

[0159] Figure 14 This is a diagram illustrating an example of the relationship between time and reactor current in a converter with a magnetically coupled reactor having two-phase coils, where the current flowing through the coil is decreasing before the phase switch from in-phase to out-of-phase, and the phase switch occurs in such a way that the current flowing through the coil decreases after the phase switch from out-of-phase to in-phase.

[0160] In this disclosure, the control that switches the current in such a way that if the current is rising before the phase switch from the same phase to a different phase, the current rises after the phase switch from the different phase to the same phase immediately following the phase switch is called "rising phase switching control".

[0161] In this disclosure, the control that switches the current in a manner such that if the current is decreasing before the phase switch from the same phase to a different phase, the current decreases after the immediate phase switch from the different phase to the same phase is called "phase switching control during a decrease".

[0162] The phase switching control during ascent and the phase switching control during descent can be performed by at least one of them.

[0163] Alternatively, phase switching control during ascent and phase switching control during descent can be implemented alternately. In this case, for example, which phase switching control was implemented immediately before the vehicle stopped can be recorded in non-volatile memory, and the phase switching control that was not implemented previously can be implemented when the vehicle is started again.

[0164] Figure 15 This is a flowchart illustrating an example of phase switching control, which is a typical example of the present disclosure.

[0165] The control unit obtains the current value (reactor current value) I flowing through the coil and the input voltage V from the power supply. L and the set output voltage V H (S101).

[0166] Then, the control unit determines the output voltage V relative to the set value. H The obtained current value I and input voltage V L To determine whether the above operating conditions (1) (S102) are met.

[0167] When it is determined that the above operating condition (1) is met, the control unit switches the phase to a different phase when driving in the same phase, and switches the phase back to the same phase when driving in a different phase, and ends the control (S103). On the other hand, when it is determined in S102 that the above operating condition (1) is not met, the control unit ends the control and does not perform phase switching control.

[0168] Figure 16 This is a flowchart illustrating an example of phase switching control, representing a specific example of the present disclosure.

[0169] The control unit obtains the current value (reactor current value) I flowing through the coil and the input voltage V from the power supply. L and the set output voltage V H (S201).

[0170] Then, the control unit determines the output voltage V relative to the set value. H The obtained current value I and input voltage V L To determine whether the above operating conditions (1) (S202) are met.

[0171] When it is determined that the above operating condition (1) is met, the control unit determines whether the current value I flowing through the coil is below the specified first switching threshold (S203).

[0172] When the current value I flowing through the coil is determined to be below the predetermined first switching threshold, the control unit switches the phase to the same phase if driving with a different phase (S204). Furthermore, when the current value I flowing through the coil is determined to be below the predetermined first switching threshold, the control unit continues to drive with the same phase in S204 if driving with the same phase.

[0173] On the other hand, when it is determined that the current value I flowing through the coil exceeds the predetermined first switching threshold, the control unit determines whether the current value I flowing through the coil is greater than or equal to the predetermined second switching threshold (S205).

[0174] When the current value I flowing through the coil is determined to be above the predetermined second switching threshold, the control unit switches the phase to a different phase while driving in the same phase (S206). Furthermore, when the current value I flowing through the coil is determined to be above the predetermined second switching threshold, the control unit continues driving in a different phase in S206 while driving in a different phase.

[0175] When it is determined in S205 that the current value I flowing through the coil is less than the specified second switching threshold, the control unit ends the control and does not perform phase switching control.

[0176] Figure 17 This is a flowchart illustrating an example of phase switching control in a variation of this disclosure, 1.

[0177] The control unit obtains the current value (reactor current value) I flowing through the coil and the input voltage V from the power supply. L and the set output voltage V H (S301).

[0178] Then, the control unit determines the output voltage V relative to the set value. H The obtained current value I and input voltage V L To determine whether the above operating conditions (1) (S302) are met.

[0179] When the above operating condition (1) is determined to be met, the control unit determines the current value I flowing through the coil and the average current value I of the reactor. L Whether they are consistent (S303).

[0180] When the current value I flowing through the coil is determined to be equal to the average current value I of the reactor... L When the phases are consistent, if the drive is in the same phase, the control unit switches the phase to a different phase; if the drive is in a different phase, the control unit switches the phase back to the same phase and ends the control (S304).

[0181] On the other hand, in S303, when it is determined that the current value I flowing through the coil is equal to the average current value I of the reactor... L If there is a discrepancy, the control unit returns to S303 to re-determine the difference between the current value I flowing through the coil and the average current value I of the reactor. L Are they consistent?

[0182] Figure 18 This is a flowchart illustrating an example of phase switching control in Modification 2 of this disclosure.

[0183] The control unit obtains the current value (reactor current value) I flowing through the coil and the input voltage V from the power supply. L and the set output voltage V H (S401).

[0184] Then, the control unit determines the output voltage V relative to the set value. H The obtained current value I and input voltage V L The control unit determines whether the above operating condition (1) is met (S402). When it is determined in S402 that the above operating condition (1) is not met, the control unit ends the control and does not perform phase switching control.

[0185] When it is determined that the above operating condition (1) is met, the control unit determines whether the current value I flowing through the coil is rising before the phase switch from the same phase to a different phase (S403).

[0186] When it is determined that the current value I flowing through the coil is rising before the phase switch from the same phase to a different phase, the control unit performs phase switching control in the rising phase after the phase switch from the same phase to a different phase, in such a way that the current value I flowing through the coil rises after the phase switch from a different phase to the same phase, and ends the control (S404).

[0187] On the other hand, if the current value I flowing through the coil is not rising before the phase switch from the same phase to a different phase, the control unit determines whether the current value I flowing through the coil is falling before the phase switch from the same phase to a different phase (S405).

[0188] When it is determined that the current value I flowing through the coil is decreasing before the phase switch from the same phase to a different phase, the control unit performs a phase switching control in the decreasing phase state after the phase switch from the same phase to a different phase, such that the current value I flowing through the coil decreases after the phase switch from a different phase to the same phase, and then ends the control (S406). When it is determined in S405 that the current value I flowing through the coil is not decreasing before the phase switch from the same phase to a different phase, that is, when the current value I flowing through the coil is neither increasing nor decreasing, the control unit ends the control and does not perform phase switching control.

Claims

1. A power supply unit, characterized in that, Includes power supply and converter, in, The converter is configured to perform at least one selection from the group consisting of boost and buck converters of the output voltage of the power supply. The converter includes an n-phase reactor with magnetically coupled coils, n-phase switches connected to the coils respectively, and a control unit. The control unit controls the duty cycle of the switches in the n phases. The control unit monitors the current value flowing through the coil of phase n. The control unit is configured to perform phase switching control when the following operating conditions are met: switching from the same phase to different phases when the switches of the n phases are driven in the same phase, and switching from different phases to the same phase when the switches of the n phases are driven in different phases. The operating conditions are as follows: When the input and output voltages of the converter are respectively predetermined voltage values, the operation is a discontinuous mode in which the current flowing through the coil is zero during one cycle of the duty cycle control when the n-phase switches are driven with the same phase; and a continuous mode in which the current flowing through the coil is zero during one cycle of the duty cycle control when the n-phase switches are driven with different phases. Where n is an integer greater than or equal to 2. The control unit is configured such that, in the phase switching control, if the current value flowing through the coil is rising before the phase switching from the same phase to a different phase, then after the phase switching from the same phase to a different phase, the phase switching occurs in such a way that the current value flowing through the coil rises after the phase switching from a different phase to the same phase.

2. The power supply unit according to claim 1, characterized in that, The control unit is configured to pre-store a data set representing the relationship between the input voltage and output voltage of the converter and the current value flowing through the coil when the operating conditions are met, and to determine whether the operating conditions are met by referring to the data set based on the input voltage and output voltage of the converter and the current value flowing through the coil of the n-phase.

3. The power supply unit according to claim 1 or 2, characterized in that, The control unit is configured to perform the phase switching control when the current value flowing through the coil is consistent with the average current value of the coil, if the operating conditions are determined to be met.

4. The power supply unit according to claim 1 or 2, characterized in that, The control unit is configured such that, in the phase switching control, if the current value flowing through the coil is decreasing before the phase switching from the same phase to a different phase, then after the phase switching from the same phase to a different phase, the phase switching occurs in such a way that the current value flowing through the coil decreases after the phase switching from a different phase to the same phase.

5. The power supply unit according to claim 1 or 2, characterized in that, The different phases are phase differences of (360 / n)°.

6. The power supply unit according to claim 1 or 2, characterized in that, The n phases are two phases. The different phases are a phase difference of 180°.

7. The power supply unit according to claim 1 or 2, characterized in that, The power source is a fuel cell.

8. The power supply unit according to claim 1 or 2, characterized in that, The control unit is configured such that, in the phase switching control, when it is determined that the current flowing through the coil is below a predetermined first switching threshold, a phase switch is performed from a different phase to the same phase. The control unit is configured to perform a phase switch from the same phase to a different phase when it is determined that the current value flowing through the coil is greater than or equal to a predetermined second switching threshold that is greater than a predetermined first switching threshold.

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