JP2010279151A - Device for detection of average reactor current - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve reliability in averages of the amount of reactor current. <P>SOLUTION: A device includes: a decision unit (201) for determining whether a period when the amount of current in a reactor (L) changes nonlinearly exists in a period of switching control of a switching element (S1); and an average estimator (203) for estimating the average of the amount of current in the reactor in the period, based on an input voltage (VL) of a voltage converter 12, an output voltage (VH), the value of the reactor (L), and a ratio (D) of an ON period of the switching element (S1) to an OFF period when the decision unit (201) determines that the period when the amount of current changes nonlinearly exists. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technique related to a voltage converter including a reactor and a switching element.

  A DC-DC converter that boosts and / or steps down a direct current (DC) voltage is known as a voltage converter. The DC-DC converter is widely used in electric devices including electric circuits, such as personal computers, AV devices, mobile phones, and power supply systems. In recent years, there is an example in which a DC-DC converter is used in a power supply system of a vehicle such as a fuel cell vehicle, an electric vehicle, and a hybrid vehicle.

International Publication No. 2006/098376

  The DC-DC converter includes, for example, a switching element and a reactor, and converts (steps up or steps down) an input DC voltage (for example, an output voltage of the fuel cell) to a predetermined output DC voltage by switching control of the switching element. Can do.

  For example, the switching control is performed such that a process of accumulating electric energy in the reactor and a process of discharging electric energy accumulated in the reactor are alternately repeated. The current flowing through the reactor (hereinafter referred to as “reactor current”) gradually increases linearly when the switching element is ON, and the reactor current gradually decreases linearly when the switching element is OFF.

  Therefore, by controlling the duty ratio of the control signal (pulse signal) that controls the ON period and OFF period of the switching element, the average reactor current amount (accumulation / release of electric energy) is controlled, and the DC-DC The average step-up ratio or step-down ratio of the converter can be controlled.

  In such switching control, a period in which the reactor current does not change linearly may occur depending on the switching pattern (duty ratio) applied to the switching element. If the average value of the reactor current amount is obtained without taking this into consideration, the reliability of the average value deteriorates. As a result, the reactor current amount (duty ratio) is feedback-controlled based on an average value with low reliability, and the control accuracy of the step-up ratio or step-down ratio of the converter may be deteriorated and the control may become unstable.

  Therefore, one of the objects of the present invention is to detect the average value of the reactor current with higher reliability even if there is a period in which the reactor current does not change linearly, thereby improving the stability of the reactor current control. There is in doing so.

  In addition, the present invention is not limited to the above-described object, and other effects of the present invention can be achieved by the functions and effects derived from the respective configurations shown in the embodiments for carrying out the invention which will be described later. It can be positioned as one of

  One aspect of the average reactor current detection device of the present invention includes a reactor and a switching element, and controls an amount of current flowing through the reactor by periodic switching control of the switching element to convert an input voltage into a predetermined output voltage. A determination unit that determines whether or not there is a period in which a current amount of the reactor changes nonlinearly in the period of the switching control, and the determination unit determines the nonlinearity If it is determined that there is a period that changes periodically, the input voltage, the output voltage, the value of the reactor, and the ratio between the ON period and the OFF period of the switching element, the reactor in the period An average value estimation unit that estimates an average value of the current amount.

  Here, the average reactor current detection device is configured to detect the current of the reactor at the center timing of the ON period or the OFF period of the switching element when the determination unit determines that the non-linearly changing period does not exist. You may provide the average value detection part which detects quantity as an average value in the said period.

  Further, the determination unit may perform the determination based on the input voltage, the output voltage, and the ratio.

  Furthermore, another aspect of the average reactor current detection device of the present invention includes a reactor and a switching element, and controls an amount of current flowing through the reactor by periodic switching control of the switching element to output an input voltage to a predetermined output. A device used for a voltage converter for converting to voltage, wherein there is a current detection unit for detecting the current amount of the reactor, and a period in which the current amount of the reactor changes nonlinearly in the period of the switching control. A determination unit that determines whether or not, and when the determination unit determines that the non-linearly changing period exists, the detection value of the current detection unit is continuously sampled and averaged, or An average value measurement unit for obtaining an integrated value of the detection values.

  Further, another aspect of the average reactor current detection device of the present invention includes a reactor and a switching element, and controls an amount of current flowing through the reactor by periodic switching control of the switching element to set an input voltage to a predetermined value. An apparatus used in a voltage converter for converting to an output voltage, the average value detection unit for detecting the current amount of the reactor at the center timing of the ON period or OFF period of the switching element as an average value in the period, and A determination unit that determines whether or not there is a period in which the current amount of the reactor changes nonlinearly in a period of the switching control; and a case in which the determination unit determines that there is a period in which the nonlinear change occurs , The input voltage, the output voltage, the value of the reactor, and the switching element Based on the ratio between the N period and OFF period, and an average value correcting unit for correcting the average value obtained by the average value detector.

  ADVANTAGE OF THE INVENTION According to this invention, when there exists the period when the electric current amount of a reactor changes nonlinearly, the reliability of the average value of a reactor electric current amount can be improved.

It is a figure showing typically an example of composition of a power supply system concerning one embodiment and vehicles carrying the power supply system. It is a figure which shows the structural example of FC boost converter and ECU shown in FIG. It is a figure which shows an example of the time change of the reactor electric current amount in a continuous mode. It is a figure which shows an example of the time change of the reactor electric current amount in discontinuous mode. It is a figure explaining the average value estimation method of the reactor electric current amount in discontinuous mode. It is a graph which illustrates the deviation of the average value of the reactor current amount in the continuous mode and the discontinuous mode. It is a figure explaining the determination conditions of continuous / discontinuous mode, (A) is an example of the time change of the reactor current amount in discontinuous mode, (B) is an example of the time change of the reactor current amount in continuous mode, respectively. Show. FIG. 4 is a block diagram illustrating a modification of the ECU illustrated in FIG. 2. It is a figure explaining the average value correction method of the reactor electric current amount in discontinuous mode. It is a graph which illustrates the deviation of the average value of the reactor current amount in the continuous mode and the discontinuous mode to explain the average value correction amount of the reactor current amount in the discontinuous mode.

  Embodiments of the present invention will be described below with reference to the drawings. However, the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described below. In other words, the present invention can be implemented with various modifications (combining the embodiments, etc.) without departing from the spirit of the present invention. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. The drawings are schematic and do not necessarily match actual dimensions and ratios. In some cases, the dimensional relationships and ratios may be different between the drawings.

[1] One Embodiment FIG. 1 is a diagram schematically illustrating a configuration example of a power supply system 10 according to an embodiment and a vehicle 1 equipped with the power supply system 10.

  The power supply system 10 is illustratively a fuel cell system having a fuel cell (FC) 11, and the vehicle 1 is a fuel cell vehicle as an example of an electrical device that uses the fuel cell system 10 as a source of driving power. . However, the vehicle 1 may be an electric vehicle or a hybrid vehicle.

  The vehicle 1 includes a motor 16 that drives the drive wheels 2, an electronic control unit (ECU) 20, an accelerator pedal sensor 21 that detects the opening of an accelerator pedal, and the like. The accelerator pedal sensor 21 is electrically connected to the electronic control unit 20. For example, the rotational speed of the motor 16 (drive wheel 2) is controlled by the ECU 20 according to the detected opening degree of the access pedal.

  In addition to the fuel cell (FC) 11, the fuel cell system 10 includes, as a non-limiting example, an FC boost converter 12, a battery 13, a battery boost converter 14, an inverter 15, and the like.

  The FC 11 is a device that generates electricity using an electrochemical reaction. Various types of fuel cells such as solid polymer type, phosphoric acid type, molten carbonate type, solid oxide type, and alkaline electrolyte type can be applied to FC11. The power generated by the FC 11 is used to drive the motor 16 that drives the drive wheels 2 of the vehicle 1 and to charge the battery 13.

  The battery 13 is a chargeable / dischargeable secondary battery, and various types of secondary batteries such as lithium ion, nickel hydride, and nickel cadmium can be applied. The battery 13 can supply electric power to various electric devices used when the vehicle 1 or the FC 11 is operated. The electrical equipment here includes, for example, lighting equipment for the vehicle 1, air conditioning equipment, a hydraulic pump, a pump for supplying fuel gas and reforming material of FC11, a heater for adjusting the temperature of the reformer, and the like.

  The FC 11 and the battery 13 are electrically connected in parallel to the inverter 15 as illustrated in FIG. An FC boost converter 12 is provided in the electrical path from the FC 11 to the inverter 15. The FC boost converter 12 is a DC-DC converter that boosts an input DC voltage, converts the DC voltage generated by the FC 11 into a predetermined DC voltage within a convertible range (for example, boosts it), and applies it to the inverter 15. Can do. Such boosting operation makes it possible to secure the driving power required to drive the motor 16 even when the output power of the FC 11 is low.

  On the other hand, the battery boost converter 14 is connected in parallel to the electrical path between the FC boost converter 12 and the inverter 15 in the electrical path from the battery 13 to the inverter 15. The converter 14 is also a DC-DC converter, and can convert the DC voltage applied from the battery 13 or the inverter 15 into a predetermined DC voltage within a convertible range.

  The converter 14 can be a step-up / step-down converter capable of both boosting and stepping down. For example, the converter 14 controls (boosts) the input DC voltage from the battery 13 and outputs it to the inverter 15 side. The input DC voltage can be controlled (stepped down) and output to the battery 13. Thereby, charging / discharging of the battery 13 is attained.

  Moreover, the converter 14 can control the terminal voltage of the inverter 15 by controlling the output voltage. This control controls the relative output voltage difference between the power supplies (FC 11 and battery 13) connected in parallel to the inverter 15, and makes it possible to properly use both powers.

  The inverter 15 receives DC voltage input from the FC 11 via the converter 12 and from the battery 13 via the converter 14, converts the input DC voltage into alternating current (AC) voltage, and drives the motor 16. Supply as voltage. At that time, the ECU 20 controls the operation (switching) of the inverter 15 so that an AC voltage corresponding to the required power is supplied to the motor 16.

  In addition to the control described above, the ECU 20 comprehensively controls the operation (operation) of the vehicle 1 and the fuel cell system 10. The ECU 20 can be exemplarily realized as a microcomputer including a CPU as an example of an arithmetic processing device, a RAM, a ROM as an example of a storage device, and the like. The ECU 20 is electrically connected to each element of the motor 16 and the fuel cell system 10 and various sensor groups, and appropriately receives various sensor values, performs arithmetic processing, transmits commands (control signals), and the like. In addition to the accelerator pedal sensor 21, the sensor group includes, for example, an SOC sensor that detects the state of charge (SOC) of the battery 13, a vehicle speed sensor that detects the vehicle speed (the number of rotations of the motor 16), and the converter 12. A current sensor or the like for detecting (monitoring) the reactor current amount at the can be included.

[2] Boost converter 12
Next, an example of an electric circuit diagram of the boost converter 12 is shown in FIG. 2 includes, for example, a reactor (coil) L, an output diode D1, capacitors C1 and C2, and a switch circuit SW including a diode D2 and a switching element S1. In FIG. 2, reference numeral 121 denotes a current sensor, 122 and 123 denote voltage sensors, both of which will be described in detail later.

  As a non-limiting example, an insulating gate bipolar transistor (IGBT) can be applied to the switching element S1.

  Reactor L has one end connected in series to the positive electrode of DC power supply (FC11) and the other end connected in series to the anode of output diode D1. In FIG. 2, the power supply voltage (the output voltage of FC11) is represented by VL.

  One end of the capacitor C1 is connected between the reactor L and the FC11, the other end of the capacitor C1 is connected to the negative electrode of the FC11, and the output voltage VL of the FC11 is applied to both ends. The capacitor C1 functions as an input smoothing capacitor that smoothes the output current of the FC 11 and reduces ripples.

  The collector of the switching element S1 is connected between the reactor L and the diode D1, and the emitter of the switching element S1 is connected to the negative electrode of the FC11. The cathode of the diode D2 is connected to the collector of the switching element S1, and the anode of the diode D2 is connected to the emitter of the switching element S1.

  One end of a capacitor C2 is connected to the cathode of the diode D1, and the other end of the capacitor C2 is connected to the negative electrode of the FC11. The capacitor C2 functions as an output smoothing capacitor that smoothes the output current supplied from the diode D1 to the motor 16 via the inverter 15 and reduces ripple. The voltage across the capacitor C2 (VH) is the boosted voltage.

  The gate voltage of the switching element S1 is periodically ON / OFF controlled by the ECU 20, for example. The switching period (carrier frequency) is about 100 ms (10 kHz) as a non-limiting example.

  During the period when the switching element S1 is ON, the output current of the FC 11 returns to the negative electrode of the FC 11 via the reactor L and the switching element S1, and electric energy is accumulated in the reactor L. On the other hand, during the period when the switching element S1 is OFF, the electric energy accumulated in the reactor L so far is superimposed on the output voltage of the FC11 and output via the output diode D1. In this way, converter 12 performs a boosting operation.

  FIG. 3 shows an example of a temporal change in the reactor current during the boosting operation. As indicated by a solid line 100 in FIG. 3, the reactor current alternately repeats linear increase / decrease (accumulation and release of electric energy) according to ON / OFF control of the switching element S1. That is, the reactor current gradually increases linearly when the switching element S1 is ON, and the reactor current gradually decreases linearly when the switching element S1 is OFF.

The ratio of the ON time in one switching period is referred to as “duty ratio” or simply “duty”. For example, when the ON time of the switching element S1 is represented by T _ON and the OFF time is represented by T _OFF , the duty D can be represented by D = T _ON / (T _ON + T _OFF ).

  The ECU 20 controls the pulse pattern (duty D) of the control signal applied to the gate of the switching element S1, thereby controlling the average reactor current amount in the switching cycle, and hence the average accumulation and release energy amount of the reactor L. it can. With this control, it is possible to control the step-up ratio of the converter 12, that is, the output voltage VH of the converter 12 applied to the inverter 15 with respect to the input voltage VL, and thus the average power supplied to the load (for example, the motor 16).

[3] Reactor current amount average value detection The control can be performed according to the required output voltage (step-up ratio) while monitoring the average reactor current amount in one switching cycle, for example. . For example, a current sensor can be used for monitoring the reactor current.

  Here, as illustrated in FIG. 3, the reactor current has a triangular waveform (see solid line 100) that linearly increases and decreases in accordance with ON / OFF of the switching element S <b> 1, so that the average reactor per switching period is averaged. The amount of current (see the dotted line 300 in FIG. 3) can be treated equivalently as the amount of reactor current at the center timing of the ON period (or OFF period) of the switching element S1.

  Therefore, as illustrated in FIG. 3, there is no period in which the reactor current amount continuously changes (linearly) and becomes zero in the switching cycle (in other words, a period in which the reactor current changes nonlinearly) The ECU 20 can be used for the control (feedback control) of the average reactor current amount with the current sensor value at the center timing of the switching element S1 equivalently as an average value. In the “continuous mode”, for example, the load (for example, the motor 16) is driven with a high output voltage such that the reactor current amount becomes non-zero when the switching element S1 is switched from OFF to ON (rising of the switching control signal). This corresponds to the case of (high output operation).

  Specifically, the reactor current amount can be detected by providing a current sensor 121 on the input side of the reactor L as illustrated in FIG. The current sensor 121 is an example of a current detection unit, and, for example, a magnetic proportional sensor can be applied. The magnetic proportional current sensor indirectly measures the magnitude of the current by measuring the magnetic field when the current to be measured flows through the conductor. For example, a magnetic field corresponding to the current is converted into a voltage signal by the Hall element, the output voltage is amplified by an amplifier circuit, and the output voltage corresponding to the current is output as a sensor value.

  Therefore, in the “continuous mode”, the ECU 20 samples the sensor value of the current sensor 121 (hereinafter also referred to as “current sensor value”) at the center timing of the ON period (or OFF period) of the switching element S1. An average value of the reactor current can be obtained.

  On the other hand, the converter 12 is used by using a switching pattern in which the average reactor current amount is lower than the switching pattern (duty ratio) in the “continuous mode”, for example, when the motor 16 is operated at a low output. May be controlled.

  In such a case, as illustrated in FIG. 4, a period in which the reactor current amount becomes zero occurs in the switching period, and current flows intermittently through the reactor L (this is referred to as “discontinuous mode”). In the “discontinuous mode”, there is a non-linearly changing period in the reactor current waveform (triangular waveform) within the switching period, so the same method as in the “continuous mode”, that is, the center timing of the ON period of the switching element S1. When the reactor current is sampled (average value monitor), a value (see dotted line 300) larger than the actual average value (see dotted line 400) is detected as the average value. As a result, the reactor current control of the converter 12 is performed based on an average value that is different from the actual average value (low reliability), and the boost control may become unstable.

  Therefore, in the “discontinuous mode”, the ECU 20 of the present embodiment detects the average value of the reactor current amount by a method different from the average value monitor at the center timing in the “continuous mode”. As an example of the method, based on the input voltage (voltage before boost) VL [V], the output voltage (voltage after boost) VH [V], the reactor value L0 [H], the duty D and the carrier frequency f. And a method of estimating an average value of the actual reactor current amount in the “discontinuous mode”. By using such an estimated average value, even in the “discontinuous mode”, the reliability of the average value of the reactor current is improved and stable current control becomes possible.

この式（１）の導出方法について、図５を参照しながら説明する。 Specifically, the average value (Lavr) of the reactor current in the “discontinuous mode” can be obtained (estimated) by the following equation (1).

A method for deriving the equation (1) will be described with reference to FIG.

  In order to obtain the average value of the reactor current in the “discontinuous mode”, the total area of the regions (right triangles) 500 and 600 shown in FIG. 5 may be obtained and averaged over one period.

First, the area of the right triangle 500 is obtained. The peak value (di) of the reactor current corresponding to the height of the right triangle 500 can be obtained by the following equation (2).

The ON time (dt1) of the switching element S1 corresponding to the length of the base of the right triangle can be obtained by the following equation (3).

From the equations (2) and (3), the peak value (di) of the reactor current can be obtained by the following equation (4). Since the right triangle 500 and the right triangle 600 have the same height, the peak value (di) corresponds to the height of the other right triangle 600.

On the other hand, the time (dt2) from when the switching element S1 is turned OFF, corresponding to the bottom of the right triangle 600, until the reactor current becomes 0 [A] can be obtained by the following equation (5).

Therefore, the average value Lavr of the reactor current can be obtained by the following equation (6). That is, the above equation (1) is derived.

  In the “discontinuous mode”, the ECU 20 can obtain the average value Lavr of the reactor current by the equation (1), and can use the average value Lavr for feedback control of the average reactor current amount.

  Therefore, as illustrated in FIG. 2, in addition to the current sensor 121 that detects the reactor current amount, the converter 12 includes a voltage sensor 122 that detects the pre-boosting voltage VL and a voltage sensor 123 that detects the post-boosting voltage VH. It is done.

  Each of the sensors 122 and 123 is electrically connected to the ECU 20 similarly to the current sensor 121, and the respective sensor values (VL and VH) are input to the ECU 20. Reactor value L0 is a known value in ECU 20 as a design value, and duty D and carrier frequency f are command values.

  Further, as illustrated in FIG. 2, the ECU 20 includes functions as a mode determination unit 201, an average value detection unit 202, an average value estimation unit 203, and a current control unit 204.

  Mode determination unit 201 determines whether the mode of converter 12 is “continuous mode” or “discontinuous mode” based on a predetermined determination condition. For example, the determination condition can be determined based on the pre-boosting voltage VL, the post-boosting voltage VH, and the duty D. For example, as shown in a comparison between FIG. 7A and FIG. 7B, in the “continuous mode” (see FIG. 8B), the relationship “dt1 + dt2> 1 / f” is established.

Here, dt1 (ON time of the switching element S1) is expressed by the above expression (3), and dt2 (time from when the switching element S1 is turned OFF until the reactor current becomes 0) is expressed by the above expression (5). Therefore, the determination condition can be expressed by the following equation (7).

  Therefore, the mode determination unit 201 determines the “continuous mode” when the sensor values VL and VH of the voltage sensors 122 and 123 and the duty D are parameters, respectively, and satisfies the condition expressed by the equation (7), and satisfies the condition. If not, it is determined as “discontinuous mode”.

  When the determination result in the mode determination unit 201 is “continuous mode”, the average value detection unit 202 calculates the sensor value obtained by the current sensor 121 at the center timing of the ON (or OFF) period of the switching element S1. It is detected as the average value of the reactor current. Note that a solid line 700 in FIG. 6 shows an example of a change in the average value of the reactor current at the center timing with respect to the duty D.

  The average value estimation unit 203 estimates the average value of the reactor current by the calculation according to the equation (1) as described above when the determination result in the mode determination unit 201 is “discontinuous mode”. FIG. 6 shows an example of a change in the estimated average value with respect to the duty D by a solid line 800. The difference between the characteristics indicated by the solid lines 700 and 800 in FIG. 6 corresponds to the deviation of the average value of the reactor current amount in the “continuous mode” and the “discontinuous mode” (see the dotted line 900).

  The current control unit 204 performs feedback control of the average reactor current based on the average value obtained by the average value detection unit 202 in the “continuous mode” and the average value obtained by the average value estimation unit 203 in the “discontinuous mode”. (Duty D control) and the like are performed.

  As described above, according to this example, in the “discontinuous mode”, when the current sensor value obtained at the center timing of the switching element S1 is not reliable as the average value of the reactor current, other parameters (converter 12 Can be estimated on the basis of the pre-boosting voltage VL, post-boosting voltage VH, reactor value L0, duty D and carrier frequency f), so that a stable current can be obtained even in the discontinuous mode. Control becomes possible.

[4] Modification (4.1) Modification 1
In the “discontinuous mode”, the ECU 20 samples a plurality of sensor values of the current sensor 121 within a range where the sampling speed and the processing capability of the CPU are allowed instead of the above-described average value estimation unit 203, and sets each sampling value as software. An average value measurement unit 203a (see FIG. 2) that averages over one switching period may be provided. Thereby, in the “discontinuous mode”, the average value of the reactor current amount can be accurately measured. Therefore, it is possible to obtain an average value with higher reliability than the average value obtained at the center timing of the ON (or OFF) period of the switching element S1.

(4.2) Modification 2
In the “discontinuous mode”, the actual measurement by the average value actual measurement unit 203a is alternatively performed by filtering the sensor value of the current sensor 121 to the extent that the transient response characteristic of the current is deteriorated and the controllability is not deteriorated (for example, You may carry out by performing a low-pass filter process. Thereby, the amplitude component of the reactor current can be integrated to obtain the areas of the regions 500 and 600 illustrated in FIG. 5, that is, the average value of the reactor current amount. Therefore, it is possible to obtain an average value with higher reliability than the average value obtained at the center timing of the ON (or OFF) period of the switching element S1.

  The low-pass filter (integration) process may be performed by providing a hardware low-pass filter in the electrical path from the current sensor 121 to the ECU 20, or may be performed by software processing in the ECU 20. If a hardware low-pass filter is used, the processing load on the ECU 20 (CPU) can be reduced.

(Modification 3)
Further, in the “discontinuous mode”, the ECU 20 samples the sensor value of the current sensor 121 at the center timing of the ON (or OFF) period of the switching element S1 as in the “continuous mode”, and corrects the sampling value. Then, the average value of the actual reactor current amount may be obtained.

  In this case, as illustrated in FIG. 8, the ECU 20 has functions as a mode determination unit 201, an average value detection unit 202, an average value correction unit 205, and a current control unit 204.

  The mode determination unit 201 determines the continuous / discontinuous mode according to the determination condition represented by the above equation (9).

  Regardless of whether the determination result in the mode determination unit 201 is the continuous mode or the discontinuous mode (in any case), the average value detection unit 202 is a switching element as illustrated in FIG. The sensor value of the current sensor 121 is sampled at the center timing of the ON (or OFF) period of S1, and the sampled value is detected as an average value of the reactor current amount.

  The average value correction unit 205 uses the current sensor value (average value) X detected by the average value detection unit 202 as the actual average reactor current when the determination result by the mode determination unit 201 is “discontinuous mode”. The amount is corrected to Z (see arrow 910 in FIG. 10). The correction corresponds to correcting the characteristic 700 in a direction that eliminates a deviation corresponding to the difference between the characteristics 700 and 800 described above in FIG.

  Here, the actual average reactor current amount Z can be obtained by Z = X−Y, where Y is the correction amount, and the correction amount Y is the estimated reactor current value at the center timing of the ON period of the switching element S1. Y1 and the estimated reactor average current Y2 can be obtained by Y = Y1-Y2.

The estimated reactor current value Y1 can be considered to be 1/2 of the peak value (di) of the reactor current represented by the above-described equation (4), and therefore can be obtained by the following equation (8), and the estimated reactor average The current Y2 can be obtained by the above equation (1).

Therefore, the correction amount Y can be obtained by the following equation (9).

  When the determination result in the mode determination unit 201 is “continuous mode”, the average value correction unit 205 does not perform the correction by the correction amount Y, and the average value detected by the average value detection unit 202 is used. Output as is. Further, the average value correction unit 205 may actually calculate the equation (9), and the Y value when each input parameter is changed is stored in advance in the memory or the like in the ECU 20 as data in a table format or a map format. The speed of the correction process may be increased by storing the data and referring to the data as necessary.

  The current control unit 204 performs feedback control of the reactor current based on the average value obtained by the average value detection unit 202 in the “continuous mode” and the average value corrected by the average value correction unit 205 in the “discontinuous mode”. (Duty D control) and the like are performed.

  As described above, according to the present example, the sensor value of the current sensor 121 having low reliability in the “discontinuous mode” is set to other parameters (the pre-boosting voltage VL, the boosting voltage VH, the reactor value L0, the converter 12). Correction can be made based on the duty D and the carrier frequency f). Therefore, a more reliable average value of the reactor current can be obtained, and stable current control can be performed even in the “discontinuous mode”.

[5] Others The embodiment described above may be applied to a step-down converter. In the case of a step-down converter, the output voltage (voltage after boost) VH of the boost converter is the input voltage (voltage before step-down) of the step-down converter, and the input voltage (voltage before boost) VL of the boost converter is the output voltage (voltage after step-down) of the step-down converter. You can think of each. Further, the above-described embodiment is not limited to the on-vehicle DC-DC converter, but can also be applied to a DC-DC converter mounted on an electric device such as a personal computer, an audio visual (AV) device, or a portable terminal. It is.

1 Vehicle 2 Drive Wheel 10 Power Supply System (Fuel Cell System)
11 Fuel cell (FC)
12 Booster Converter 13 Battery 14 Battery Booster Converter 15 Inverter 16 Motor 20 Electronic Control Unit (ECU)
DESCRIPTION OF SYMBOLS 21 Accelerator pedal sensor 121 Current sensor 122,123 Voltage sensor 201 Mode determination part 202 Average value detection part 203 Average value estimation part 204 Current control part 205 Average value correction part C1, C2 Capacitor D1, D2 Diode S1 Switching element SW Switch circuit

Claims (5)

A device comprising a reactor and a switching element, and used in a voltage converter that controls an amount of current flowing through the reactor by periodic switching control of the switching element and converts an input voltage into a predetermined output voltage,
A determination unit that determines whether or not there is a period in which the current amount of the reactor changes nonlinearly in the period of the switching control;
Based on the input voltage, the output voltage, the value of the reactor, and the ratio between the ON period and the OFF period of the switching element when the determination unit determines that the period that changes nonlinearly exists. An average value estimating unit for estimating an average value of the current amount of the reactor in the cycle,
An average reactor current detection device.   An average for detecting, as an average value in the period, the current amount of the reactor at the center timing of the ON period or the OFF period of the switching element when it is determined by the determination unit that the non-linearly changing period does not exist The average reactor current detection device according to claim 1, comprising a value detection unit. The determination unit
The average reactor current detection device according to claim 1, wherein the determination is performed based on the input voltage, the output voltage, and the ratio. A device comprising a reactor and a switching element, and used in a voltage converter that controls an amount of current flowing through the reactor by periodic switching control of the switching element and converts an input voltage into a predetermined output voltage,
A current detector for detecting the current amount of the reactor;
A determination unit that determines whether or not there is a period in which the current amount of the reactor changes nonlinearly in the period of the switching control;
When the determination unit determines that the non-linearly changing period exists, the detection value of the current detection unit is continuously sampled and averaged, or the integral value of the detection value is obtained. A value measurement unit;
An average reactor current detection device. A device comprising a reactor and a switching element, and used in a voltage converter that controls an amount of current flowing through the reactor by periodic switching control of the switching element and converts an input voltage into a predetermined output voltage,
An average value detection unit that detects the current amount of the reactor at the center timing of the ON period or the OFF period of the switching element as an average value in the period;
A determination unit that determines whether or not there is a period in which the current amount of the reactor changes nonlinearly in the period of the switching control;
Based on the input voltage, the output voltage, the value of the reactor, and the ratio between the ON period and the OFF period of the switching element when the determination unit determines that the period that changes nonlinearly exists. An average value correction unit for correcting the average value obtained by the average value detection unit,
An average reactor current detection device.

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