JP2007295785A - Control unit for converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately control a charge voltage of an accessory battery. <P>SOLUTION: An ECU executes a program including a step (S100) for detecting a current supplied from a DC-DC converter to the accessory battery and a step (S200) for correcting an output voltage of the DC-DC converter so that the magnitude of the voltage increases with that of current supplied to the accessory battery. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a converter control device, and in particular, converts a voltage between a first power storage mechanism and a second power storage mechanism, and supplies electric power output from the first power storage mechanism to a second power storage mechanism. The present invention relates to a technology for controlling a converter.

  Conventionally, a hybrid vehicle, an electric vehicle, a fuel cell vehicle, and the like that can be driven by a driving force of a rotating electric machine such as a motor have attracted attention. In these vehicles, a driving power source such as a battery or a capacitor (condenser) for storing electric power supplied to the rotating electrical machine is mounted. Since it is necessary to drive the vehicle, the voltage of the power source for driving is generally high and is not suitable as a power source for auxiliary equipment such as an air conditioner and an audio. Therefore, an auxiliary battery having a lower voltage than the driving power source is mounted separately from the driving power source. The auxiliary battery can be supplied with electric power from a driving power source via a DC / DC converter that converts voltage.

  By the way, when charging the auxiliary battery, the charging voltage that can be allowed by the auxiliary battery varies depending on the temperature of the auxiliary battery itself. If the charging voltage of the auxiliary battery is not properly controlled and is charged with an overvoltage or a low voltage, the battery will be deteriorated and the battery life will be adversely affected. Therefore, it is necessary to change the output voltage of the DC / DC converter, that is, the charging voltage of the auxiliary battery according to the temperature of the auxiliary battery.

  Japanese Patent Application Laid-Open No. 7-107619 (Patent Document 1) discloses an auxiliary battery charging device for an electric vehicle that eliminates overcharge (at high temperature) and insufficient charge (at low temperature) that occur with changes in the temperature of an auxiliary battery. Disclose. An auxiliary battery charging device for an electric vehicle described in Patent Document 1 includes a main battery that obtains driving power for driving, an auxiliary battery that operates vehicle auxiliary machines, and a voltage that charges the auxiliary battery with the voltage of the main battery. A conversion unit (DC / DC converter) and a temperature detection unit that detects a temperature change of the auxiliary battery are included. The output signal of the temperature detection unit is input to the voltage conversion means, and the output voltage of the voltage conversion unit is changed.

According to the auxiliary battery charging apparatus for an electric vehicle described in this publication, a temperature change of the auxiliary battery is detected by the temperature detection unit. Based on this signal, the output voltage of the voltage converter is changed. Thereby, the charging voltage of the auxiliary battery can be set to a predetermined value corresponding to the temperature change.
JP-A-7-107619

  By the way, when the electric current output from the DC / DC converter is supplied to the auxiliary battery as in the auxiliary battery charging apparatus for an electric vehicle described in JP-A-7-107619, the auxiliary battery is charged. The voltage is lower than the output voltage of the DC / DC converter. This is because the voltage itself drops because the harness itself connecting the DC / DC converter and the auxiliary battery has resistance. However, in Japanese Patent Laid-Open No. 7-107619, no consideration is given to a voltage drop caused by a harness connecting a DC / DC converter and an auxiliary battery. Since the voltage drop due to the harness changes depending on the current value, there is room for further improvement in terms of accurately controlling the charging voltage of the auxiliary battery.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a converter control device capable of accurately controlling a charging voltage.

  The control device for the converter according to the first invention converts the voltage between the first power storage mechanism and the second power storage mechanism, and supplies the power output from the first power storage mechanism to the second through the conductor. The converter supplied to the power storage mechanism is controlled. This control device controls the converter so that the output voltage of the converter changes according to the current detection means for detecting the current supplied to the second power storage mechanism and the current detected by the current detection means. Control means.

  According to the first invention, the current supplied to the second power storage mechanism is detected by the current detection means. The converter is controlled so that the output voltage of the converter changes according to the current detected by the current detection means. Thereby, the output voltage of the converter can be increased according to the current flowing through the conductor between the converter and the second power storage mechanism and the voltage drop due to the resistance of the conductor itself. Therefore, it is possible to prevent the charging voltage of the second power storage mechanism from unintentionally decreasing. As a result, it is possible to provide a control device for a converter that can accurately control the charging voltage.

  According to the converter control device of the second invention, in addition to the configuration of the first invention, the control means converts the converter so that the output voltage of the converter increases as the current value detected by the current detection means increases. Means for controlling.

  According to the second invention, the converter is controlled so that the output value of the converter increases as the current value detected by the current detection means, that is, the current value supplied to the second power storage mechanism via the conductor increases. Is done. Thereby, the output voltage of a converter can be made high, so that the fall of the voltage by the electric current which flows through a conductor, and resistance of conductor itself is large. Therefore, it is possible to prevent the charging voltage of the second power storage mechanism from unintentionally decreasing.

  In addition to the configuration of the first or second invention, the converter control device according to the third invention includes a means for determining a failure of the current detection means, and if a failure of the current detection means is determined, the failure is detected. And a means for controlling the converter such that the output voltage of the converter is higher than when not determined.

  According to the third aspect of the invention, when the failure of the current detection means is determined, the output voltage of the converter is made higher than when the failure is not determined. Thereby, it can suppress that the charge voltage of a 2nd electrical storage mechanism falls. Therefore, it is possible to prevent the remaining capacity of the second power storage mechanism from being insufficient.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

<First Embodiment>
With reference to FIG. 1, a hybrid vehicle equipped with a control device according to a first embodiment of the present invention will be described. The vehicle includes an engine 100, an MG (Motor Generator) (1) 200, an MG (2) 300, a power split mechanism 400, an inverter (1) 500, an inverter (2) 600, a main battery 700, DC / DC converter 900 and auxiliary battery 910 are included. This vehicle travels by driving force from at least one of engine 100 and MG (2) 300.

  In the present embodiment, a hybrid vehicle that travels by driving force from at least one of the engine and MG will be described. However, a hybrid vehicle that travels only by driving force from MG, an electric vehicle, and fuel It may be a battery car or the like.

  Engine 100, MG (1) 200, and MG (2) 300 are connected via power split device 400. The power generated by the engine 100 is divided into two paths by the power split mechanism 400. One is a path for driving a wheel (not shown) via a reduction gear. The other is a path for driving MG (1) 200 to generate power.

  MG (1) 200 is a three-phase AC motor. The MG (1) 200 generates power using the power of the engine 100 divided by the power split mechanism 400. The electric power generated by the MG (1) 200 depends on the vehicle running state and the SOC (State Of) of the main battery 700. Depending on (Charge), it can be used properly. For example, during normal travel, the electric power generated by MG (1) 200 becomes electric power for driving MG (2) 300 as it is. On the other hand, when the SOC of main battery 700 is lower than a predetermined value, the electric power generated by MG (1) 200 is converted from AC to DC by inverter 500. Thereafter, electric power is stored in main battery 700. It is noted that power may be stored in main battery 700 by adjusting the voltage with a converter.

  MG (2) 300 is a three-phase AC motor. MG (2) 300 is driven by at least one of the electric power stored in main battery 700 and the electric power generated by MG (1) 200. MG (2) 300 is supplied with electric power converted from direct current to alternating current by inverter (2) 600.

  The driving force of MG (2) 300 is transmitted to the wheels via the speed reducer. Thereby, MG (2) 300 assists engine 100 or causes the vehicle to travel by the driving force from MG (2) 300.

  On the other hand, at the time of regenerative braking of the hybrid vehicle, MG (2) 300 is driven by the wheels via the speed reducer, and MG (2) 300 is operated as a generator. Thereby, MG (2) 300 acts as a regenerative brake that converts braking energy into electric power. The electric power generated by MG (2) 300 is stored in main battery 700 via inverter (2) 600.

  The main battery 700 is an assembled battery configured by connecting a plurality of battery modules in which a plurality of battery cells are integrated in series. Instead of the main battery 700, a capacitor, a fuel cell, or the like may be used.

  The auxiliary battery 910 stores electric power mainly supplied to auxiliary devices such as the air conditioner 920 and the audio 930. For example, a lead storage battery is used for auxiliary battery 910. In the present embodiment, the voltage of auxiliary battery 910 is lower than the voltage of main battery 700. The charging voltage for auxiliary battery 910 is adjusted by DC / DC converter 900.

  The auxiliary battery 910 is supplied with power output from the main battery 700 via the DC / DC converter 900. The DC / DC converter 900 and the auxiliary battery are connected by harnesses 902 and 904. That is, the electric power output from the DC / DC converter 900 is supplied to the auxiliary battery 910 via the harnesses 902 and 904. The DC / DC converter 900 is controlled so that the voltage between the terminals of the auxiliary battery 910 becomes a voltage that can be said to be a fully charged state.

  At this time, the charging voltage that can be allowed by auxiliary battery 910 varies depending on the temperature of auxiliary battery 910. Therefore, as shown in FIG. 2, the output voltage of DC / DC converter 900 is controlled to be lower as the temperature of auxiliary battery 910 is higher.

  Returning to FIG. 1, engine 100, inverter (1) 500, inverter (2) 600 and DC / DC converter 900 are controlled by ECU (Electronic Control Unit) 1000. ECU 1000 includes HV (Hybrid Vehicle) _ECU 1010, MG_ECU 1020, and engine ECU 1030.

  The HV_ECU 1010 receives a signal representing the voltage of the auxiliary battery 910 from the voltage sensor 912 and a signal representing the current charged in the auxiliary battery 910 from the current sensor 914.

  Further, the HV_ECU 1010 receives a signal representing the vehicle speed from the vehicle speed sensor 2000, a signal representing the opening of the accelerator pedal (not shown) from the accelerator opening sensor 2100, and a pedaling force of the brake pedal (not shown) from the brake pedal force sensor 2200. Are respectively input.

  The MG_ECU 1020 is supplied with a signal representing the rotational speed of the MG (1) 200 from the rotational speed sensor 202 and a signal representing the rotational speed of the MG (2) 300 from the rotational speed sensor 302. Engine ECU 1030 receives a signal representing the rotational speed of engine 100 from rotational speed sensor 102.

  The HV_ECU 1010, the MG_ECU 1020, and the engine ECU 1030 are connected so that signals can be transmitted / received to / from each other. In the present embodiment, the HV_ECU 1010 is used to accelerate or decelerate the vehicle based on a map or the like stored in a memory (not shown) using vehicle speed, accelerator opening, brake pedal force, etc. as parameters. The required output value is calculated as follows.

  In order to satisfy this output value, the required output value to engine 100, MG (1) 200 and MG (2) 300, and the required power amount for system power (main battery 700 and auxiliary battery 910) (from system power to MG (1) Amount of power required as an output value to 200 or MG (2) 300 is calculated.

  For example, the requested output value to engine 100 and MG () (MG (2) 300 are shared by the requested output value to engine 100 and the requested output value to MG (2) 300 when the vehicle is accelerated. 2) A required output value to 300 is calculated. That is, the sum of the required output value for engine 100 and the required output value for MG (2) 300 matches the output value of the vehicle.

  Further, the required output value to the MG (1) 200 and the system power supply are supplied so that the MG (2) 300 is supplied with power necessary for driving the MG (2) 300 so as to satisfy the required output value. The required power amount is calculated.

  When MG (1) 200 or MG (2) 300 is operated as a generator, the required output value is calculated as a negative value. As a method for calculating the required output value, the required power amount, and the like, since a known technique may be used, further detailed description will not be repeated here.

  With reference to FIG. 3, a control structure of a program executed by ECU 1000 which is the control apparatus according to the present embodiment will be described. Note that the program described below is repeatedly executed at a predetermined cycle.

  In step (hereinafter, step is abbreviated as S) 100, ECU 1000 detects the current supplied (charged) to auxiliary battery 910 based on the signal transmitted from current sensor 914.

  In S200, ECU 1000 corrects the output voltage of DC / DC converter 900 so as to increase as the current value supplied to auxiliary battery 910 increases. Thereafter, this process ends.

  An operation of ECU 1000 that is the control device according to the present embodiment based on the above-described structure and flowchart will be described.

  In a state where current is supplied to the auxiliary battery 910, the charging voltage of the auxiliary battery 910 is the harnesses 902 and 904 that connect the DC / DC converter 900 and the auxiliary battery 910 from the output voltage of the DC / DC converter 900. This is a value obtained by subtracting the voltage drop due to the current flowing through and the resistances of the harnesses 902 and 904 themselves.

  The voltage drop in the harnesses 902 and 904 between the DC / DC converter 900 and the auxiliary battery 910 may change according to the current supplied from the DC / DC converter 900 to the auxiliary battery 910. Therefore, if the output voltage of the DC / DC converter 900 is controlled without corresponding to the current supplied from the DC / DC converter 900 to the auxiliary battery 910, the charging voltage of the auxiliary battery 910 may be higher than expected. Can be lowered.

  Therefore, the current supplied to the auxiliary battery 910 is detected (S100), and the output voltage of the DC / DC converter 900 increases as the current value supplied to the auxiliary battery 910 increases as shown in FIG. (S200).

  As a result, the output voltage of the DC / DC converter 900 can be increased by the amount of voltage drop due to the current flowing through the harnesses 902 and 904 and the resistance of the harnesses 902 and 904 itself. Therefore, it can suppress that the charging voltage of auxiliary battery 910 falls. Further, since the output voltage of DC / DC converter 900 is increased by the amount of voltage decrease in harnesses 902 and 904, it is possible to suppress the charging voltage of auxiliary battery 910 from becoming excessive. Therefore, the auxiliary battery 910 can be accurately controlled so that the charging voltage of the auxiliary battery 910 becomes an appropriate voltage.

  As described above, according to the ECU that is the control device according to the present embodiment, the output voltage of the DC / DC converter is corrected so as to increase as the current value supplied to the DC / DC converter increases. As a result, the output voltage of the DC / DC converter can be increased by the amount of decrease in voltage due to the current flowing through the harness between the DC / DC converter and the auxiliary battery and the resistance of the harness itself. Therefore, it can suppress that the charging voltage of an auxiliary machine battery falls. Moreover, since the output voltage of the DC / DC converter is increased by the amount of voltage decrease in the harness, it is possible to suppress the charging voltage of the auxiliary battery from becoming excessive. As a result, a change in the charging voltage of the auxiliary battery can be suppressed, and the remaining capacity of the auxiliary battery can be accurately controlled.

<Second Embodiment>
Hereinafter, a second embodiment of the present invention will be described. In the present embodiment, when the current sensor 914 fails, the output voltage of the DC / DC converter is corrected so as to be higher than when the current sensor 914 is not broken. It differs from the form. Other structures are the same as those in the first embodiment. The function about them is the same. Therefore, detailed description thereof will not be repeated here.

  With reference to FIG. 5, a control structure of a program executed by ECU 1000 that is the control device according to the present embodiment will be described. Note that the program described below is repeatedly executed at a predetermined cycle. The program described below is executed in addition to the program in the first embodiment described above.

  In S300, ECU 1000 determines whether or not current sensor 914 is out of order. For example, in a state where the DC / DC converter 900 is controlled to output electric power, if the current value detected by the current sensor 914 is “0”, it is determined that the current sensor 914 is faulty. It should be noted that whether or not current sensor 914 is faulty may be determined using other known general techniques, and therefore, detailed description thereof will not be repeated here. If current sensor 914 is out of order (YES in S300), the process proceeds to S400. Otherwise (NO in S300), this process ends.

  In S400, ECU 1000 corrects the output voltage of DC / DC converter 900 so as to be higher than the case where it is not determined that there is a failure. For example, as shown in FIG. 6, when it is determined that the current sensor 914 is out of order, the output voltage of the DC / DC converter 900 is maximized regardless of the current value. Thereafter, this process ends.

  An operation of ECU 1000 that is the control device according to the present embodiment based on the above-described structure and flowchart will be described.

  If current sensor 914 is faulty (YES in S300), the output voltage of DC / DC converter 900 is corrected so as to be higher than when it is not determined that it is faulty (S400).

  Thereby, it can suppress that the charging voltage of the auxiliary battery 910 falls. Therefore, the auxiliary battery SOC can be prevented from being insufficient. As a result, malfunction of auxiliary equipment such as the air conditioner 920 and the audio 930 can be suppressed.

  As described above, according to the ECU that is the control device according to the present embodiment, when the current sensor that detects the current value supplied to the DC / DC converter fails, compared to the case where it does not fail. The output voltage of the DC / DC converter is corrected so as to increase. Thereby, it can suppress that the charging voltage of an auxiliary machine battery falls. Therefore, the auxiliary battery SOC can be prevented from being insufficient.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a schematic configuration diagram showing a hybrid vehicle equipped with a control device according to a first embodiment of the present invention. FIG. 3 is a diagram (part 1) illustrating an output voltage of a DC / DC converter. It is a flowchart which shows the control structure of the program performed by ECU of FIG. 1 which is a control apparatus which concerns on the 1st Embodiment of this invention. FIG. 6 is a diagram (part 2) illustrating an output voltage of the DC / DC converter. It is a flowchart which shows the control structure of the program performed by ECU which is a control apparatus which concerns on the 2nd Embodiment of this invention. FIG. 6 is a third diagram illustrating the output voltage of the DC / DC converter.

Explanation of symbols

  100 Engine, 200 MG (1), 300 MG (2), 400 Power split mechanism, 500 Inverter (1), 600 Inverter (2), 700 Main battery, 900 DC / DC converter, 910 Auxiliary battery, 912 Voltage sensor , 914 Current sensor, 920 Air conditioner, 930 Audio, 1000 ECU, 1010 HV_ECU, 1020 MG_ECU, 1030 Engine ECU.

Claims (3)

A control device for a converter that converts a voltage between a first power storage mechanism and a second power storage mechanism, and supplies electric power output from the first power storage mechanism to the second power storage mechanism via a conductor. Because
Current detection means for detecting current supplied to the second power storage mechanism;
And a control means for controlling the converter so that the output voltage of the converter changes in accordance with the current detected by the current detection means.   2. The converter control device according to claim 1, wherein the control means includes means for controlling the converter such that an output voltage of the converter increases as a current value detected by the current detection means increases. . The control device comprises means for determining a failure of the current detection means;
The apparatus further comprises means for controlling the converter so that the output voltage of the converter is higher when a failure of the current detection means is determined than when a failure is not determined. 3. The converter control device according to 2.

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