DC / DC converter control device

Abstract

DC / DC converter control device, wherein a DC / DC converter (100) comprises an inductor (102) of which one end is connected to a DC power source (1) and which has a circuit (107) configured to include a plurality of semiconductor switching devices (103, 104) and which is connected to another end of the inductor (102), and which converts an input voltage supplied by the DC power source (1) and outputs a voltage after conversion of the input voltage supplied by the DC power source (1) as an output voltage, wherein the DC / DC converter control device comprises: a low-voltage-side voltage sensor (203) for detecting a low-voltage-side voltage which is the input voltage; a low-voltage side voltage detector (403) for outputting a voltage detected by the low-voltage side voltage sensor (203); a first high-voltage-side voltage sensor (201a) for detecting a high-voltage-side voltage which is the output voltage; a first high-voltage-side voltage detector (401) for outputting a voltage detected by the first high-voltage-side voltage sensor (201a); a second high-voltage-side voltage sensor (201b) for detecting the high-voltage-side voltage, which is the output voltage; a second high-voltage-side voltage detector (402) for outputting a voltage detected by the second high-voltage-side voltage sensor (201b); and a fault detection means (301) for detecting a fault of the first high-voltage-side voltage sensor (201a) and a fault of the second high-voltage-side voltage sensor (201b), wherein a switching control is carried out when the plurality of semiconductor switching devices (103, 104) are switched on or off, using: a low-voltage detection voltage (V1) using the low-voltage voltage detector (403), a first high-voltage detection voltage (V2S) using the first high-voltage voltage detector (401), a second high-voltage detection voltage (V2M) by means of the second high-voltage-side voltage detector (402), and wherein, if a fault of the first high-voltage-side voltage sensor (201a) or a fault of the second high-voltage-side voltage sensor (201b) is detected, by a comparison between the first high-voltage-side detection voltage (V2S) or the second high-voltage-side detection voltage (V2M) and a high-voltage-side estimation voltage (V2est), a high-voltage side semiconductor switching device (104), which is connected between one end of the choke (102) and that of the DC / DC converter (100) on its high-voltage side, is switched on, and a fault of a non-faulty one of the first high-voltage side voltage sensor (201a) and the second high-voltage side voltage sensor (201b) is detected, using a non-faulty one of the high-voltage side detection voltage (V2S) and the second high-voltage side detection voltage (V2M).

Description

TECHNICAL AREA

[0001] The present invention relates to a control device for a DC / DC converter. STATE OF THE ART

[0002] A conventional DC / DC converter (electrical power conversion device) consists of a device with terminal groups, a choke and a switching device circuit connected in series, and the device performs a buck-boost conversion of a voltage from a battery to an electric motor.

[0003] The terminal groups include a first terminal and a second terminal, and the series-connected switching device circuit is a circuit whose first switching device and second switching device are connected in series.

[0004] As for the pair of switching devices connected in series, one connection point of the first switching device and the second switching device is connected to the first terminal via the choke, and a side opposite the connection point of the first switching device and the second switching device is connected to the second terminal.

[0005] The first terminal is defined as the low-voltage side and the second terminal as the high-voltage side, so that the conversion of DC voltages between the low-voltage side and the high-voltage side takes place.

[0006] The DC / DC converter has a calculation tool and an on / off control tool.

[0007] The calculation tool calculates a value based on the voltage difference between a high-voltage-side voltage instruction value, which is a voltage instruction value on the high-voltage side, and a high-voltage-side voltage detection value, which is a detection value of a high-voltage-side voltage, or on the voltage difference between a low-voltage-side voltage instruction value, which is a voltage instruction value on the low-voltage side, and a low-voltage-side voltage detection value, which is a detection value of a low-voltage-side voltage.

[0008] The on / off control device detects a switching ratio based on the calculated value and controls the on / off operations of the first switching device and the second switching device based on the switching ratio (e.g. see JP 5 457 559 B2).

[0009] US Patent 6,978,213 B2 relates to a voltage conversion system. In this system, a battery voltage is amplified in a converter and serves as the input to another converter that supplies a motor with drive current. A control unit detects the input and output voltages of the converter from the outputs of voltage sensors and controls the switching in the converter according to these detected voltages. If one of the sensors fails, the control unit estimates the voltage that would otherwise have been detected by the failed sensor, based on the switching state in the converter and the voltage detected by the remaining sensor.

[0010] DE 11 2016 005 127 T5 relates to an overboost suppression circuit for a boost converter, which is controlled by a control circuit to raise an input voltage to a prescribed target voltage, wherein the overboost suppression circuit includes: a detection unit that detects an overboost in which a voltage is raised above the prescribed target voltage of the boost converter; and a voltage boost stop unit which, when the overboost is detected by the detection unit, causes the control circuit to stop a voltage boost operation of the boost converter in order to maintain an output voltage of the boost converter at a voltage that is higher than the prescribed target voltage and lower than or equal to a withstand voltage value of a peripheral circuit element, which is a load.

[0011] KR 10 2009 062 339 A concerns a method for diagnosing a defect in a DC-DC converter of an electric vehicle in order to extend the service life of the DC-DC converter and an auxiliary battery in a hybrid / fuel cell vehicle by quickly diagnosing the defect of the DC-DC converter.

[0012] US 7,425,782 B2 relates to a voltage conversion device comprising a forward-direction conversion circuit for converting an input voltage from a DC power source into a desired output voltage by adjusting the relative duty cycle of semiconductor switching elements. The device further includes a control section that controls the relative duty cycle according to at least one target output voltage and an output voltage such that the output voltage approximates the target output voltage. Based on an operating value of the control section, it is determined whether a fault has occurred. Thus, it becomes possible to determine whether a fault has occurred without forming a binary system.

[0013] JP 2009 213 246 A relates to a method for accurately detecting a fault in a DC / DC converter, which can perform continuous monitoring and can also deal with an amplifier fluctuation fault or an offset fluctuation fault. SUMMARY OF THE INVENTION [Problems to be solved by the invention]

[0014] In a conventional DC / DC converter, the state of a high-voltage-side voltage sensor is always detected by the voltage sensor to detect a high-voltage-side voltage, so that a fault or error determination is carried out, regardless of whether a detected value is normal or abnormal.

[0015] In a case where a voltage sensor for detecting a high-voltage-side voltage is not caused to fail, the DC / DC converter is put into normal operation and the voltage conversion is carried out by a switching operation, whereas in a case where a voltage sensor for detecting a high-voltage-side voltage is caused to fail, the detection of a high-voltage-side voltage is no longer possible and thus the second switching device is set in an on state.

[0016] If a voltage sensor for detecting a high-voltage-side voltage fails, the control continues while a high-voltage-side voltage and a low-voltage-side voltage maintain a certain constant dependency in between; however, the voltage sensor for detecting the high-voltage-side voltage is caused to fail, and therefore, if an operation of an electric motor on a power generation / traction part changes, a change in this in a high-voltage-side voltage cannot be detected, so the operations cannot be achieved in a safe state.

[0017] This means that if the high voltage is too high, a fault occurs in the circuit of the DC / DC converter, while if the high voltage is too low, a voltage required to control the electric motor is missing, resulting in an out-of-control state.

[0018] The present invention aims to solve these problems described above, and one objective of the invention is to prevent a malfunction of the circuit or a fault of a DC / DC converter with respect to a fault of voltage sensors which each detect a high-voltage-side voltage in the DC / DC converter, and to enable continuous control of the DC / DC converter. [Means of solving the problems]

[0019] The problems are solved according to the invention by the subject matter of the independent claims. The dependent claims relate to further embodiments, and this description explains how the invention can be carried out.

[0020] In a DC / DC converter control device according to the present invention, wherein a DC / DC converter comprises an inductor, one end of which is connected to a DC power source and which has a circuit configured to include a plurality of semiconductor switching devices and which is connected to another end of the inductor, and which converts an input voltage supplied by the DC power source and outputs a voltage after the input voltage has been converted to an output voltage, the control device comprises: a low-voltage-side voltage sensor for detecting a low-voltage-side voltage which is the input voltage; a low-voltage-side voltage detector for outputting a voltage as detected by the low-voltage-side voltage sensor; a first high-voltage-side voltage sensor for detecting a high-voltage-side voltage which is the output voltage;a first high-voltage-side voltage detector for outputting a voltage as detected by the first high-voltage-side voltage sensor; a second high-voltage-side voltage sensor for detecting the high-voltage-side voltage, which is the output voltage; a second high-voltage-side voltage detector for outputting a voltage as the output thereof, which is detected by the second high-voltage-side voltage sensor;and a fault detection means for detecting a fault of the first high-voltage-side voltage sensor and the second high-voltage-side voltage sensor, wherein a switching control is carried out when the plurality of semiconductor switching devices are switched on or off, using a low-voltage-side detection voltage with the aid of the low-voltage-side voltage detector, a first high-voltage-side detection voltage with the aid of the first high-voltage-side voltage detector, and a second high-voltage-side detection voltage with the aid of the second high-voltage-side voltage detector. [Effects of the invention]

[0021] According to the DC / DC converter control device of the present invention, two voltage sensors are included for detecting a high-voltage-side voltage of a DC / DC converter, making it possible to monitor the deviation of one voltage sensor for detecting a high-voltage-side voltage while the high-voltage-side semiconductor switching device is switched on; and thus, even if one voltage sensor for detecting a high-voltage-side voltage fails, it is possible to monitor the high-voltage-side voltage using the other voltage sensor for detecting the high-voltage-side voltage, where no fault detection occurs, and to perform fault detection of the high-voltage-side voltage, so that a malfunction or fault of the DC / DC converter can be prevented and the DC / DC converter can be continuously controlled. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a configuration diagram representing a configuration of a DC / DC converter control device according to embodiment 1 of the present invention; Fig. Figure 2 is a configuration diagram illustrating a configuration of a DC / DC converter control device according to embodiment 2 of the present invention; Fig. Figure 3 is a flowchart illustrating the sequence of control operations for performing the estimation of a high-voltage-side estimation voltage and the fault detection of voltage sensors in the DC / DC converter control device according to embodiment 2 of the present invention; Fig. Figure 4 is a diagram showing a correlation between an induced voltage of an electric motor at a drive element and its rotational speed in the DC / DC converter control device according to embodiment 2 of the present invention; Fig. Figure 5 is a diagram showing a correlation between an induced voltage of an electric motor on a power generation part and its rotational speed in the DC / DC converter control device according to embodiment 2 of the present invention; Fig. Figure 6 is a configuration diagram showing a configuration of a DC / DC converter control device according to embodiments 3 and 4 of the present invention; Fig. Figure 7 is a flowchart illustrating a processing sequence for detecting a voltage sensor fault when an induced voltage in the DC / DC converter control device according to embodiment 3 of the present invention is low; Fig. Figure 8 is a flowchart illustrating the processing sequence for fault detection of a voltage sensor for detecting a high-voltage-side voltage in the DC / DC converter control device according to embodiment 3 of the present invention; Fig. Figure 9 is a flowchart illustrating the processing sequence for fault detection of a voltage sensor for detecting a high-voltage-side voltage in the DC / DC converter control device according to embodiment 3 of the present invention; and Fig. Figure 10 is a flowchart illustrating a processing sequence for detecting a fault of voltage sensors for detecting a high-voltage-side voltage when a high-voltage-side estimating voltage in the DC / DC converter control device according to embodiment 4 of the present invention is low. EXECUTIONAL FORMS FOR IMPLEMENTING THE INVENTION Execution form 1.

[0022] Fig. Figure 1 illustrates a configuration example of a DC / DC converter control device, which is an embodiment of the present invention; first, the description of embodiment 1 is given.

[0023] The control device of a DC / DC converter according to embodiment 1 of the present invention is configured in the manner described below.

[0024] As in Fig. As shown in Figure 1, a DC / DC converter (electrical power conversion device) 100 comprises an inductor 102, a semiconductor module 107 forming a circuit and consisting of a first semiconductor switching device (low-voltage side semiconductor switching device) 103 and a second semiconductor switching device (high-voltage side semiconductor switching device) 104 and a low-voltage side capacitor 101; and thus the DC / DC converter is configured to be controlled by means of a control device 300.

[0025] Furthermore, a high-voltage battery 1, which is a DC power source, is connected to the low-voltage side (via terminals 100a and 100b) of the DC / DC converter 100, and an electric motor 2 is connected to the high-voltage side (via terminals 100c and 100d) of the same. The electric motor 2 is equipped with an inverter for controlling the power output of the DC / DC converter 100, and thus in Fig. Figure 1 shows the inverter as it is integrated into the electric motor 2. The electric motor 2 generates a driving force by receiving its electrical energy supply from a DC source that is electrically connected to the inverter. Furthermore, it can be assumed that the electric motor 2 also functions as an electric generator.

[0026] The inverter described above is a DC / AC conversion device that performs electrical power conversion between the DC power source and the electric motor 2. The inverter is designed as a bridge circuit, in which two series-connected switching devices are provided with a set of three pairs of terminals, corresponding to the respective three-phase (phase-U, phase-V, and phase-W) windings of the electric motor 2, between a positive electrode wiring line connected to the positive electrode of the DC power source and a negative electrode wiring line connected to the negative electrode of the DC power source. A terminal connecting a switching device on the positive electrode side and a switching device on the negative electrode side in series is connected to a winding corresponding to each of the phases.A chip of an IGBT (Insulated Gate Bipolar Transistor), a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or the like is used as a switching device, to which a freewheeling diode is connected in antiparallel.

[0027] Fig. Figure 1 illustrates a system of one electric motor, but there is also a system of two electric motors. In such a case, one electric motor is used as a drive unit, and the other electric motor is used as a power generation unit.

[0028] It should be noted that each of the semiconductor switching devices 103 and 104 consists individually of, for example, an IGBT and an antiparallel connected diode.

[0029] Furthermore, the DC / DC converter 100 has a first voltage sensor 201a for detecting a high-voltage voltage and a second voltage sensor 201b for the same purpose, as well as a voltage sensor 203 for detecting a low-voltage voltage. In a fault detection device 301, a value from the first voltage sensor 201a for detecting a high-voltage voltage is output to a first high-voltage-side voltage detector 401; a value from the second voltage sensor 201b for detecting the high-voltage voltage is output to a second high-voltage-side voltage detector 402; and a value from the voltage sensor 203 for detecting a low-voltage voltage is output to a low-voltage-side voltage detector 403. A detection value from an electric current sensor 202 for detecting an electric current flowing through the inductor 102 is input into the control device 300.

[0030] In Fig. 1, the DC / DC converter (electrical power conversion device) 100 is a type of bidirectional device in which: a bidirectional electrical power conversion is enabled between the low-voltage side and the high-voltage side; the device is arranged such that an input voltage (low-voltage side voltage) which is applied via terminal 100a and terminal 100b, which are low-voltage side terminals, is increased or raised to a voltage of the input voltage (low-voltage side voltage) or more, and that an output voltage (high-voltage side voltage) is output after raising via terminal 100c and terminal 100d, which are high-voltage side terminals.

[0031] As with the first semiconductor switching device 103, one end is connected to the negative electrode-side terminal of the low-voltage-side capacitor 101 and the other end is connected to the positive electrode-side terminal of the low-voltage-side capacitor 101 via the choke 102.

[0032] As with the second semiconductor switching device 104, one end of it is connected to the other end of the first semiconductor switching device 103, and the other end of the first semiconductor switching device is connected to a positive electrode-side terminal of a high-voltage-side capacitor 105. The negative electrode-side terminal of the high-voltage-side capacitor 105 is connected to one end of the first semiconductor switching device 103. Additionally, a high-voltage-side electrical discharge resistor 106 is connected in parallel with the high-voltage-side capacitor 105.

[0033] The low-voltage-side capacitor 101 smooths the input voltage (low-voltage-side voltage). The inductor 102 is intended for use in energy storage. The semiconductor module 107 amplifies the input voltage (low-voltage-side voltage) to an output voltage (high-voltage-side voltage). It should be noted that each of the semiconductor switching devices 103 and 104 in the semiconductor module 107 is switched on when a gate signal for each device is high in the embodiments. The high-voltage-side capacitor 105 smooths the output voltage (high-voltage-side voltage). The high-voltage-side electrical discharge resistor 106 is used to release the electrical charges stored in the high-voltage-side capacitor 105.The control device 300 generates the gate signal for each of the semiconductor switching devices 103 and 104 and performs the switching on and off operations on each of the semiconductor switching devices 103 and 104.

[0034] In the fault detection device 301, when a fault (or failure) of the first voltage sensor 201a for detecting a high-voltage-side voltage is detected, based on a first high-voltage-side detection voltage V2S detected by the first high-voltage-side voltage detector 401, the control device 300 switches on the second semiconductor switching device 104 and also detects a fault of the second voltage sensor 201b for detecting the high-voltage-side voltage using a second high-voltage-side detection voltage V2M output by the second high-voltage-side voltage detector 402.According to this arrangement, the control device 300 switches on the second semiconductor switching device 104 and can also detect anomalies of a high-voltage-side output voltage by using the first high-voltage-side detection voltage V2S, which was monitored by the first high-voltage-side voltage detector 401, so that the operations can be achieved continuously even after a fault of the first voltage sensor 201a for detecting the high-voltage-side voltage or after a fault of the second voltage sensor 201b for detecting the high-voltage-side voltage. Design 2.

[0035] The following is an explanation for embodiment 2 of the present invention.

[0036] Fig. Figure 2 is a configuration diagram illustrating a DC / DC converter control device to describe embodiment 2 of the present invention.

[0037] The basic configuration of the DC / DC converter control device in embodiment 2 is the same as in embodiment 1; however, in embodiment 2, as in Fig. Figure 2 shows an operating information detection device 302 that receives operating information (rotational speed N of an electric motor and switching information of the second semiconductor switching device 104) of the electric motor 2 and monitors its individual states. A high-voltage-side voltage estimator 303 is also provided, and information is input into it by the first high-voltage-side voltage detector 401, the second high-voltage-side voltage detector 402, and the operating information detection device 302.

[0038] Fig. Figure 3 is a flowchart illustrating an estimation method for a high-voltage-side estimation voltage to explain embodiment 2 of the present invention and a processing sequence to detect a fault of the first voltage sensor 201a for detecting a high-voltage-side voltage and of the second voltage sensor 201b for detecting the high-voltage-side voltage from a high-voltage-side estimation voltage and high-voltage-side detection voltages.

[0039] As in Fig. As shown in Figure 3, in the state of an inverter controlling the electric motor 2, whose gates all demonstrate "switch off" (step S201), an initial value of a high-voltage-side estimating voltage V2est and an initial value of a sampling period Tsamp are first set (step S202). From the rotational speed N of an electric motor, an induced voltage Vtrc (power traction section) of the electric motor is calculated, and a high-voltage-side estimating voltage V2est is also calculated in the high-voltage-side voltage estimator 303 from an initial value of a high-voltage-side estimating voltage V2est, a sampling period Tsamp, a maximum value of the high-voltage-side capacitor 105, Cmax, and a maximum value of the high-voltage-side discharge resistor 106, Rmax (step S203).

[0040] If the difference between a first high-voltage-side detection voltage V2S and a high-voltage-side estimation voltage V2est is a predetermined value that is predefined, or more (step S204), a fault of the first voltage sensor 201a for detecting a high-voltage-side voltage is detected (step S205), and the second semiconductor switching device 104 is switched on (step S206).

[0041] If the difference between a second high-voltage-side detection voltage V2M and a high-voltage-side estimation voltage V2est is a predetermined value that is predefined, or more (step S207), a fault of the second voltage sensor 201b for detecting the high-voltage-side voltage is detected (step S208), and the second semiconductor switching device 104 is switched on (step S209).

[0042] If one of the conditions described above is not met, an initial value of a high-voltage-side estimating voltage V2est and an initial value of a sampling period Tsamp are set a second time (step S210), and a high-voltage-side estimating voltage V2est is calculated from the initial value of a high-voltage-side estimating voltage V2est and the initial value of a sampling period Tsamp (step S203). Here, as with an initial value V2ini of a high-voltage-side estimating voltage V2est, a value is set at the maximum of the high-voltage-side estimating voltage V2est, a first high-voltage-side detection voltage V2S, a second high-voltage-side detection voltage V2M, the induced voltage Vtrc (power traction section) of an electric motor, and the induced voltage Vgen of an electric motor (power generation section).It should be noted that the induced voltage Vtrc or Vgen of the electric motor is calculated from the number of revolutions N of the electric motor.

[0043] Since the high-voltage estimated voltage is not a monitored value but an estimated value, fault detection can be carried out without adding one or more sensors.

[0044] In this embodiment, a configuration is made using the high-voltage-side spark resistor as the spark discharge medium; however, similar effects can be achieved even if a different configuration is made using a DC circuit or the like.

[0045] Fig. 4 and Fig. Figure 5 are diagrams that each show a correlation between an induced voltage of an electric motor and its rotational speed in embodiment 2 of the present invention. Fig. Figure 4 shows a correlation between the rotational speed N of the electric motor 2 and an induced voltage Vtrc thereof at a power traction section (in a power operation state) of the electric motor in a range of a maximum rotational speed Nmax thereof and a maximum induced voltage Vtrcm thereof; and Fig. Figure 5 shows a correlation between the rotational speed N of the electric motor 2 and an induced voltage Vgen thereof at a power generation part (in the state of power generation and / or regenerative operation) in a range of a maximum rotational speed Nmax and a maximum induced voltage Vgenm.

[0046] As in Fig. 4 and Fig. As shown in Figure 5, it is possible to detect the induced voltage Vtrc or Vgen of an electric motor proportional to the rotational speed N of the electric motor by deriving the induced voltage Vtrc or Vgen of the electric motor from the rotational speed N of the electric motor; and in a system with two electric motors, the rotational speeds of the two electric motors are measured, and the induced voltages Vtrc and Vgen of the electric motors are detected at a drive component and a power generation component, respectively. Design 3.

[0047] The following is a description of embodiment 3 of the present invention.

[0048] Fig. Figure 6 is a configuration diagram illustrating a DC / DC converter control device to describe embodiment 3 of the present invention.

[0049] The basic configuration of the DC / DC converter control device in embodiment 3 is the same as in Fig. 1; however, in embodiment 3 a battery voltage detector 404 is provided to output information about a voltage that was detected by means of a battery voltage sensor 204 for detecting a voltage of the high-voltage battery 1, as in Fig. Figure 6 shows the following. Additionally, a fault detector 304 is provided, into which the outputs of the first high-voltage-side voltage detector 401, the second high-voltage-side voltage detector 402, the low-voltage-side voltage detector 403, and the battery voltage detector 404 are fed to detect a fault in the first voltage sensor 201a and the second voltage sensor 201b. Furthermore, a processing unit 501 is provided, which performs the processing when the induced voltage of the electric motor 2 is low.

[0050] Fig. Figure 7 is a diagram describing embodiment 3 of the present invention, which is the flowchart for detecting a fault of the voltage sensors for detecting a high-voltage-side voltage after switching on the second semiconductor switching device 104 when the induced voltages of the electric motor 2 are low.

[0051] As in Fig. 7, if the difference between a battery voltage Vbatt of the high-voltage battery 1 and the induced voltage Vtrc of an electric motor (power traction part) is a predetermined value that is predefined, or more, and if the difference between the battery voltage Vbatt and the induced voltage Vgen of an electric motor (power generation part) is a predetermined value that is predefined, or more (step S501), the second semiconductor switching device 104 is switched on (step S502), and a fault or error determination is carried out for the first voltage sensor 201a for detecting a high-voltage-side voltage and the second voltage sensor 201b for detecting the high-voltage-side voltage (step S503).

[0052] Fig. 8 and Fig. Figure 9 are corresponding diagrams to illustrate embodiment 3 of the present invention, which are the flowcharts that depict the fault determination processes for the first voltage sensor 201a for detecting a high-voltage-side voltage and the second voltage sensor 201b for detecting the high-voltage-side voltage, and detailed flowcharts of a fault determination processing section at step S503 in Fig. 7 for the first voltage sensor 201a for detecting a high-voltage-side voltage and the second voltage sensor 201b for detecting the high-voltage-side voltage.

[0053] As in Fig. Figure 8 shows that, according to a condition of an absolute value of the difference between a low-voltage detection voltage V1 and a first high-voltage detection voltage V2S and an absolute value of the difference between a battery voltage Vbatt and the first high-voltage detection voltage V2S (step S601), it is detected / confirmed whether the first voltage sensor 201a for detecting a high-voltage voltage fails or not (step S602 or step S603).

[0054] Namely, if the absolute value of the difference between a first high-voltage-side detection voltage V2S and a low-voltage-side detection voltage V1 is a predetermined value that is defined in advance, or less, and if the absolute value of the difference between a first high-voltage-side detection voltage V2S and a battery voltage Vbatt is a predetermined value that is defined in advance, or more, then a fault determination condition of the first voltage sensor 201a for detecting a high-voltage-side voltage is maintained.Furthermore, if the absolute value of the difference between the first high-voltage-side detection voltage V2S and the low-voltage-side detection voltage V1 is not a predetermined value that is predefined, or less, or if the absolute value of the difference between the first high-voltage-side detection voltage V2S and the battery voltage Vbatt is not a predetermined value that is predefined, or more, then a fault determination condition of the first voltage sensor 201a for detecting a high-voltage-side voltage is not met.

[0055] Furthermore, as in Fig. Figure 9 shows that, according to a condition of an absolute value of the difference between a low-voltage detection voltage V1 and a second high-voltage detection voltage V2M and an absolute value of the difference between a battery voltage Vbatt and the second high-voltage detection voltage V2M (step S701), it is recognized / confirmed whether the second voltage sensor 201b fails to detect a high-voltage voltage or not (step S702 or step S703).

[0056] Namely, if the absolute value of the difference between a second high-voltage-side detection voltage V2M and a low-voltage-side detection voltage V1 is a predetermined value that is defined in advance, or less, and if the absolute value of the difference between a second high-voltage-side detection voltage V2M and a battery voltage Vbatt is a predetermined value that is defined in advance, or more, then a fault determination condition of the second voltage sensor 201b for detecting a high-voltage-side voltage is maintained.Furthermore, if the absolute value of the difference between the second high-voltage-side detection voltage V2M and the low-voltage-side detection voltage V1 is not a predetermined value that is predefined, or less, or if the absolute value of the difference between the second high-voltage-side detection voltage V2M and the battery voltage Vbatt is not a predetermined value that is predefined, or more, then a fault determination condition of the second voltage sensor 201b for detecting a high-voltage-side voltage is not met.

[0057] As described above, the determination is carried out to determine whether the first voltage sensor 201a fails to detect a high-voltage-side voltage or whether the second voltage sensor 201b fails to detect a high-voltage-side voltage.

[0058] Afterwards, fault detection can be performed without adding one or more new sensors, and when the induced voltages Vtrc and Vgen of the electric motor are low, fault detection is performed while the second semiconductor switching device 104 is switched on; thus, by switching on the second semiconductor switching device 104, it is possible to prevent a condition in which the induced voltage Vtrc of an electric motor is higher than a battery voltage Vbatt, and to prevent overcharging of the battery, although it is feared that in a case in which the induced voltages Vtrc and Vgen of the electric motor are higher than the battery voltage Vbatt due to the counter-electromotive force of the electric motor, the battery will be overcharged and that the battery will deteriorate. Design 4.

[0059] The following describes embodiment 4 of the present invention. The basic configuration of a DC / DC converter control device in embodiment 4 is the same as in embodiment 4. Fig. 1; however, in embodiment 4 a processing unit 502 is provided, as in Fig. 6 shown, which receives information from the high-voltage-side voltage estimator 303 and performs the processing when a high-voltage-side estimator voltage is low.

[0060] Fig. Figure 10 is a diagram describing embodiment 4 of the present invention, which is the flowchart showing the sequence to detect a sensor fault after the second semiconductor switching device 104 has been switched on when a high-voltage-side estimating voltage is low.

[0061] As in Fig. 10 shown, if a high-voltage side estimated voltage V2est is a predetermined value that is predefined, or less (step S801), the second semiconductor switching device 104 is switched on (step S802) and a fault determination is carried out for the first voltage sensor 201a to detect a high-voltage side voltage and the second voltage sensor 201b to detect the high-voltage side voltage (step S803).

[0062] Meanwhile, the fault detection processing section is in Fig. 10 for the first voltage sensor 201a for detecting a high-voltage-side voltage and the second voltage sensor 201b for detecting the high-voltage-side voltage equal to or similar to the section of the housing in embodiment 3 described above.

[0063] That is, similar to in Fig. Figure 8 shows that, according to a condition of an absolute value of the difference between a first high-voltage-side detection voltage V2S and a low-voltage-side detection voltage V1 and an absolute value of the difference between the first high-voltage-side detection voltage V2S and a battery voltage Vbatt (step S601), it is detected / confirmed whether the first voltage sensor 201a fails to detect a high-voltage-side voltage or not (step S602 or step S603).

[0064] If the absolute value of the difference between a first high-voltage-side detection voltage V2S and a low-voltage-side detection voltage V1 is a predetermined value that is defined in advance, or less, and if the absolute value of the difference between the first high-voltage-side detection voltage V2S and a battery voltage Vbatt is a predetermined value that is defined in advance, or more, then an error determination condition of the first voltage sensor 201a for detecting a high-voltage-side voltage is maintained.

[0065] Furthermore, if the absolute value of the difference between the first high-voltage-side detection voltage V2S and the low-voltage-side detection voltage V1 is not a predetermined value that is predefined, or less, or if the absolute value of the difference between the first high-voltage-side detection voltage V2S and the battery voltage Vbatt is not a predetermined value that is predefined, or more, then a fault determination condition of the first voltage sensor 201a for detecting a high-voltage-side voltage is not met.

[0066] Furthermore, similar to in Fig. Figure 9 shows that, according to the condition of an absolute value of the difference between a low-voltage detection voltage V1 and a second high-voltage detection voltage V2M (step S701), it is detected / confirmed whether the second voltage sensor 201b fails to detect a high-voltage voltage or not (step S702 or step S703).

[0067] If the absolute value of the difference between a second high-voltage-side detection voltage V2M and a low-voltage-side detection voltage V1 is a predetermined value that is predefined, or less, and if the absolute value of the difference between the second high-voltage-side detection voltage V2M and a battery voltage Vbatt is a predetermined value that is predefined, or more, then an error determination condition of the second voltage sensor 201b for detecting a high-voltage-side voltage is achieved.Furthermore, if the absolute value of the difference between the second high-voltage-side detection voltage V2M and the low-voltage-side detection voltage V1 is not a predetermined value that is predefined, or less, or if the absolute value of the difference between the second high-voltage-side detection voltage V2M and the battery voltage Vbatt is not a predetermined value that is predefined, or more, then a fault determination condition of the second voltage sensor 201b for detecting a high-voltage-side voltage is not met.

[0068] As described above, the determination is carried out to determine whether the first voltage sensor 201a fails to detect a high-voltage-side voltage or whether the second voltage sensor 201b fails to detect a high-voltage-side voltage.

[0069] Accordingly, even in a state where one of the first voltage sensors 201a for detecting a high-voltage-side voltage and the second voltage sensor 201b for detecting a high-voltage-side voltage are caused to fail, the DC / DC converter can safely perform its gate switching in a state in which it does not experience any overvoltages. Design 5.

[0070] The following describes embodiment 5 of the present invention. The basic configuration of a DC / DC converter control device in embodiment 5 is the same as in embodiment 5. Fig. 1 shown.

[0071] The detection accuracy of the first voltage sensor 201a for detecting a high-voltage-side voltage is arranged to be higher than that of the second voltage sensor 201b for detecting the high-voltage-side voltage, and the detection delay of the second voltage sensor 201b for detecting the high-voltage-side voltage is arranged to be shorter than that of the first voltage sensor 201a for detecting a high-voltage-side voltage. A key feature of the configuration is that the DC / DC converter controls its output voltage using the first voltage sensor 201a for detecting a high-voltage-side voltage, and an inverter of the electric motor 2 controls the electric motor 2 using the second voltage sensor 201b for detecting the high-voltage-side voltage.The configuration described above eliminates the need to use sensors with the same function together, thus reducing costs by distributing their functions. Design 6.

[0072] The following describes embodiment 6 of the present invention. The basic configuration of a DC / DC converter control device in embodiment 6 is the same as in embodiment 6. Fig. 1 shown.

[0073] The detection accuracy of the first voltage sensor 201a for detecting a high-voltage-side voltage is arranged such that it is higher in accuracy than that of the second voltage sensor 201b for detecting the high-voltage-side voltage described above, and a detection delay of the first voltage sensor 201a for detecting a high-voltage-side voltage is arranged such that it is shorter than that of the second voltage sensor 201b for detecting the high-voltage-side voltage.One feature is the configuration in which the DC / DC converter controls its output voltage using the first voltage sensor 201a to detect a high-voltage-side voltage, and an inverter of the electric motor 2 controls the electric motor 2 using the first voltage sensor 201a to detect a high-voltage-side voltage, and that if a fault is detected in the first voltage sensor 201a, the second voltage sensor 201b is used to detect the high-voltage-side voltage. The configuration described above allows the second voltage sensor 201b to be implemented cost-effectively.

[0074] In the embodiments, it was explained that there are two semiconductor switching devices; however, in a configuration using three or more semiconductor switching devices, effects similar to those described above can be achieved. [Explanation of numbers and symbols]

[0075] The digit "1" denotes a high-voltage battery; "100" DC / DC converter; "101" low-voltage-side capacitor; "102" choke; "103" first semiconductor switching device (low-voltage-side semiconductor switching device); "104" second semiconductor switching device (high-voltage-side semiconductor switching device); "105" high-voltage-side capacitor; "106" high-voltage-side electrical discharge resistor; "201a" first voltage sensor; "201b" second voltage sensor; "203" voltage sensor; "204" battery voltage sensor; "300" control device; "301" fault detection device; "302" operating information detection device; "303" high-voltage-side voltage estimator; "304" fault detector; "401" first high-voltage-side voltage detector; "402" second high-voltage-side voltage detector; “403” low-voltage side voltage detector; “404” battery voltage detector; and “501”, “502” processing equipment.

Claims

[1] DC / DC converter control device, wherein a DC / DC converter (100) comprises an inductor (102) of which one end is connected to a DC power source (1) and which has a circuit (107) configured to include a plurality of semiconductor switching devices (103, 104) and which is connected to another end of the inductor (102) and converts an input voltage supplied by the DC power source (1) and outputs a voltage after conversion of the input voltage supplied by the DC power source (1), wherein the DC / DC converter control device comprises: a low-voltage-side voltage sensor (203) for detecting a low-voltage-side voltage which is the input voltage; a low-voltage side voltage detector (403) for outputting a voltage detected by the low-voltage side voltage sensor (203); a first high-voltage-side voltage sensor (201a) for detecting a high-voltage-side voltage which is the output voltage; a first high-voltage-side voltage detector (401) for outputting a voltage detected by the first high-voltage-side voltage sensor (201a); a second high-voltage-side voltage sensor (201b) for detecting the high-voltage-side voltage, which is the output voltage; a second high-voltage-side voltage detector (402) for outputting a voltage detected by the second high-voltage-side voltage sensor (201b); and a fault detection means (301) for detecting a fault of the first high-voltage-side voltage sensor (201a) and a fault of the second high-voltage-side voltage sensor (201b), wherein a switching control is carried out when the plurality of semiconductor switching devices (103, 104) are switched on or off, using: a low-voltage detection voltage (V1) using the low-voltage voltage detector (403), a first high-voltage detection voltage (V2S) using the first high-voltage voltage detector (401), a second high-voltage detection voltage (V2M) by means of the second high-voltage-side voltage detector (402), and wherein, if a fault of the first high-voltage-side voltage sensor (201a) or a fault of the second high-voltage-side voltage sensor (201b) is detected, by a comparison between the first high-voltage-side detection voltage (V2S) or the second high-voltage-side detection voltage (V2M) and a high-voltage-side estimation voltage (V2est), a high-voltage side semiconductor switching device (104), which is connected between one end of the choke (102) and that of the DC / DC converter (100) on its high-voltage side, is switched on, and a fault of a non-faulty one of the first high-voltage side voltage sensor (201a) and the second high-voltage side voltage sensor (201b) is detected, using a non-faulty one of the high-voltage side detection voltage (V2S) and the second high-voltage side detection voltage (V2M). [2] DC / DC converter control device according to claim 1, wherein the fault of the non-faulty one of the first high-voltage side voltage sensor (201a) and the second high-voltage side voltage sensor (201b) is detected using the non-faulty one of the first high-voltage side detection voltage (V2S) and the second high-voltage side detection voltage (V2M) and using the low-voltage side detection voltage (V1) output by the low-voltage side voltage detector (403) corresponding to the low-voltage side voltage sensor (203). [3] DC / DC converter control device according to claim 1, wherein, if an induced voltage information of an electric motor (2) to indicate an induced voltage (Vtrc, Vgen) calculated from a number of revolutions (N) of the electric motor (2) connected to the DC / DC converter, and a drive information to indicate a switching state of the high-voltage side semiconductor switching device (104) has a state in which the high-voltage side semiconductor switching device (104) is fixed in the state of being switched off, the high-voltage side estimated voltage (V2est) is estimated according to the information of the induced voltage (Vtrc, Vgen) applied to an electrical discharge resistor (106) of the DC / DC converter, and with a maximum value (Cmax) of the electrical discharge resistor (106) and a maximum value (Rmax) of a high-voltage side capacitor (105) of the DC / DC converter (100). [4] DC / DC converter control device according to claim 1, further comprising an operational information acquisition device (302) for acquiring induced voltage information of an electric motor (2) for displaying an induced voltage (Vtrc, Vgen) of the electric motor (2) which is connected to the DC / DC converter, where, if a difference between a voltage (Vbatt) of the DC power source (1) and an induced voltage (Vtrc, Vgen) of the electric motor (2) is a predetermined value that is defined in advance, or more, the high-voltage side semiconductor switching device (104) is switched on, a fault of the first high-voltage-side voltage sensor (201a) is detected by a comparison between the low-voltage-side detection voltage (V1) and the first high-voltage-side detection voltage (V2S), and A fault in the second high-voltage side voltage sensor (201b) is detected by a comparison between the low-voltage side detection voltage (V1) and the second high-voltage side detection voltage (V2M). [5] DC / DC converter control device according to claim 4, further comprising a high-voltage-side voltage estimator (303) for estimating the high-voltage-side estimated voltage (V2est) from an induced voltage information of the electric motor (2) and from a drive information to indicate a switching state of the high-voltage-side semiconductor switching device (104), wherein the high-voltage side semiconductor switching device (104) is switched on when the high-voltage side estimating voltage (V2est) of the DC / DC converter (100), obtained by the high-voltage side voltage estimators (303), is a predetermined value that is defined in advance, or less.

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