Charge control device for vehicle

A resistor is connected to first and second terminals included in a vehicle inlet. To the first terminal, a control pilot line used for transmitting a pilot signal is connected. In the case where the vehicle inlet is not connected to a connector, a switch is turned off. A voltage generation circuit sets the potential of the second terminal to a potential higher than a vehicle earth potential. In the case where the vehicle inlet is not connected to the connector and the control pilot line is broken, the potential generated on the control pilot line is substantially equal to the earth potential level. Based on the potential of the control pilot line, a control unit detects a break.

This nonprovisional application is based on Japanese Patent Application No. 2007-275003 filed on Oct. 23, 2007 with the Japan Patent Office, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a charge control device for a vehicle, and particularly to a charge control device for a vehicle that is configured to be capable of charging a power storage device used for driving the vehicle, with electric power from a power supply outside the vehicle.

2. Description of the Background Art

An electric-powered vehicle is mounted with a power storage device (such as secondary battery or capacitor for example) and travels by using driving force generated from electric power stored in the power storage device. The electric-powered vehicle includes, for example, electric vehicle, hybrid vehicle and fuel-cell vehicle.

In recent years, a technique has been proposed for charging a power storage device mounted on such electric-powered vehicles as described above by a commercial power supply having a high power generation efficiency. With this technique, increase in fuel consumption efficiency of the hybrid vehicle for example can be expected. In particular, attention is given to a technique for charging a power storage device mounted on an electric-powered vehicle by a commercial power supply providing electric power to each household (a source of a relatively low voltage such as 100 V or 200 V, for example). In the following, a vehicle having a power storage device such as a battery mounted on the vehicle and configured to be chargeable by an external power supply for the vehicle is also referred to as “plug-in vehicle.”

A technique has heretofore been proposed that is used for detecting an abnormality occurring while a power storage device mounted on a vehicle is charged. For example, Japanese Patent Laying-Open No. 2000-270484 discloses an abnormality detection device capable of detecting an abnormality such as a break of a commercial power supply line or power failure. The abnormality detection device can detect an abnormality as described above after charging of an electric-powered vehicle is started.

Standards for the plug-in vehicle are established in the United States by “SAE Electric Vehicle Conductive Charge Coupler” (“SAE Electric Vehicle Conductive Charge Coupler,” (US), SAE Standards, SAE International, November 2001), and established in Japan by “General Requirements for Electric Vehicle Conductive Charging System” (“General Requirements for Electric Vehicle Conductive Charging System,” Japan Electric Vehicle Association Standard (Japan Electric Vehicle Standard), Mar. 29, 2001).

“SAE Electric Vehicle Conductive Charge Coupler” and “General Requirements for Electric Vehicle Conductive Charging System” define standards regarding for example a control pilot. The control pilot is defined as a control line connecting a control circuit for an EVSE (Electric Vehicle Supply Equipment) which supplies electric power from an on-premises power line to a vehicle and a ground portion of the vehicle via a vehicle-side control circuit. Based on a pilot signal transmitted via the control line, the state of connection of a charge cable is detected, whether or not electric power can be supplied from a power supply to the vehicle is determined, or the rated current of the EVSE is detected, for example.

“SAE Electric Vehicle Conductive Charge Coupler” and “General Requirements for Electric Vehicle Conductive Charging System,” however, do not particularly define details of how to detect a break of the control line through which the pilot signal is transmitted. For example, from the mere fact that the potential of the control line is at the ground level, it cannot be determined whether the control line is broken, failure of power supply occurs or a charge cable is unintentionally disconnected from a receptacle. In the following, an abnormality in electric power supply to a vehicle, such as failure of power supply and unintentional disconnection of the charge cable from a receptacle, for example, is referred to as “power-supply-side abnormality.”

The pilot signal is a requisite signal for controlling charging of the plug-in vehicle as described above. It is therefore extremely important for the plug-in vehicle to detect an abnormality in the pilot signal, especially detect a break of the control line through which the pilot signal is transmitted.

The abnormality detection device disclosed in Japanese Patent Laying-Open No. 2000-270484 cannot detect an abnormality unless the commercial power supply is connected to the vehicle. This abnormality detection device is therefore considered to be capable of detecting a power-supply-side abnormality only.

SUMMARY OF THE INVENTION

The present invention has been made for solving the above-described problem, and an object of the invention is to provide a charge control device for a vehicle that can detect a break of a control line through which a pilot signal is transmitted.

Another object of the invention is to provide a charge control device for a vehicle that can detect a power-supply-side abnormality.

According to an aspect of the present invention, there is provided a charge control device for a vehicle mounted with a power storage device for driving the vehicle, the charge control device being capable of charging the power storage device with a supply electric power from a power supply outside the vehicle in a case where the vehicle and the power supply are connected by a coupler. The coupler outputs a supply electric power signal indicating information about the supply electric power in a case where the coupler is connected to the vehicle and the power supply. The charge control device includes: a control line for transmitting the supply electric power signal; a resistor having one end connected to the control line; a potential setting circuit setting a potential of the other end of the resistor to a first potential in a case where the vehicle is connected to the coupler and setting the potential of the other end of the resistor to a second potential higher than the first potential in a case where the vehicle is not connected to the coupler; and an abnormality detection unit detecting a break of the control line based on a potential of the control line in a case where the vehicle is not connected to the coupler.

Preferably, the abnormality detection unit detects occurrence of the break of the control line in a case where the potential of the control line is different from the second potential.

Preferably, the charge control device further includes a charge connector configured to be connectable to the coupler. The charge connector includes a terminal receiving the supply electric power signal by being connected to the control line. The first potential is a vehicle earth potential. The potential setting circuit includes: a connection circuit electrically connecting the other end of the resistor to the vehicle earth potential when the charge connector is connected to the coupler and disconnecting the other end of the resistor from the vehicle earth potential when the charge connector is not connected to the coupler; and a pull-up circuit pulling up the potential of the other end of the resistor to the second potential when the charge connector is not connected to the coupler.

Preferably, the charge control device further includes a vehicle speed detection device detecting speed of the vehicle. The abnormality detection unit determines that the vehicle is not connected to the coupler and detects whether or not the break of the control line occurs in a case where the vehicle speed detection device detects that the speed of the vehicle is different from zero.

preferably, the abnormality detection unit detects an abnormality in supply of the supply electric power by the power supply based on the potential of the control line in a case where the vehicle is connected to the coupler.

Preferably, the charge control device further includes: a first AC rotating electric machine including a star-connected first polyphase winding as a stator winding; a second AC rotating electric machine including a star-connected second polyphase winding as a stator winding; a first inverter connected to the first polyphase winding for performing electric power conversion between the first AC rotating electric machine and the power storage device; a second inverter connected to the second polyphase winding for performing electric power conversion between the second AC rotating electric machine and the power storage device; a pair of electric power lines connected to a first neutral point of the first polyphase winding and to a second neutral point of the second polyphase winding, for providing the supply electric power from the power supply to the first neutral point and the second neutral point; and a charge control unit controlling the first inverter and the second inverter such that the electric power provided from the pair of electric power lines to the first neutral point and the second neutral point is voltage-converted to charge the power storage device.

Preferably, the vehicle includes a drive unit configured to be capable of driving the vehicle using electric power stored in the power storage device. The charge control device further includes: a charger connected in parallel with the drive unit to the power storage device and configured to be capable of providing the supply electric power from the power supply to the power storage device; and an electric power line provided between the charge connector and the charger for transmitting the supply electric power.

According to another aspect of the present invention, there is provided a charge control device for a vehicle mounted with a power storage device for driving the vehicle, the charge control device being capable of charging the power storage device with a supply electric power from a power supply outside the vehicle in a case where the vehicle and the power supply are connected by an EVSE (Electric Vehicle Supply Equipment). The EVSE outputs a pilot signal indicating information about the supply electric power in a case where the EVSE is connected to the vehicle and the power supply. The charge control device includes: a control pilot line for transmitting the pilot signal; a resistor having one end connected to the control pilot line; a potential setting circuit setting a potential of the other end of the resistor to a first potential in a case where the vehicle is connected to the EVSE and setting the potential of the other end of the resistor to a second potential higher than the first potential in a case where the vehicle is not connected to the EVSE; and an abnormality detection unit detecting a break of the control pilot line based on a potential of the control pilot line in a case where the vehicle is not connected to the EVSE.

Preferably, the abnormality detection unit detects occurrence of the break of the control pilot line in a case where the potential of the control pilot line is different from the second potential.

Preferably, the charge control device further includes a vehicle inlet configured to be connectable to the EVSE. The vehicle inlet includes a terminal receiving the pilot signal by being connected to the control pilot line. The first potential is a vehicle earth potential. The potential setting circuit includes: a connection circuit electrically connecting the other end of the resistor to the vehicle earth potential when the vehicle inlet is connected to the EVSE and disconnecting the other end of the resistor from the vehicle earth potential when the vehicle inlet is not connected to the EVSE; and a pull-up circuit pulling up the potential of the other end of the resistor to the second potential when the vehicle inlet is not connected to the EVSE.

Preferably, the charge control device further includes a vehicle speed detection device detecting speed of the vehicle. The abnormality detection unit determines that the vehicle is not connected to the EVSE and detects whether or not the break of the control pilot line occurs in a case where the vehicle speed detection device detects that the speed of the vehicle is different from zero.

Preferably, the abnormality detection unit detects an abnormality in supply of the supply electric power by the power supply based on the potential of the control pilot line in a case where the vehicle is connected to the EVSE.

Preferably, the charge control device further includes: a first AC rotating electric machine including a star-connected first polyphase winding as a stator winding; a second AC rotating electric machine including a star-connected second polyphase winding as a stator winding; a first inverter connected to the first polyphase winding for performing electric power conversion between the first AC rotating electric machine and the power storage device; a second inverter connected to the second polyphase winding for performing electric power conversion between the second AC rotating electric machine and the power storage device; a pair of electric power lines connected to a first neutral point of the first polyphase winding and to a second neutral point of the second polyphase winding, for providing the supply electric power from the power supply to the first neutral point and the second neutral point; and a charge control unit controlling the first inverter and the second inverter such that the electric power provided from the pair of electric power lines to the first neutral point and the second neutral point is voltage-converted to charge the power storage device.

Preferably, the vehicle includes a drive unit configured to be capable of driving the vehicle using electric power stored in the power storage device. The charge control device further includes: a charger connected in parallel with the drive unit to the power storage device and configured to be capable of providing the supply electric power from the power supply to the power storage device; and an electric power line provided between the vehicle inlet and the charger for transmitting the supply electric power.

Accordingly, the present invention can detect a break of the control line through which the pilot signal is transmitted as well as a power-supply-side abnormality while distinguishing the break and the abnormality from each other.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, like or corresponding components are denoted by like reference characters, and a description thereof will not be repeated.

In the embodiments of the present invention, a plug-in hybrid vehicle is exemplified as an electric-powered vehicle chargeable by an external power supply. The electric-powered vehicle chargeable by an external power supply, however, is not limited to the plug-in hybrid vehicle and may be an electric vehicle or fuel-cell vehicle, for example.

First Embodiment

A vehicle100according to a first embodiment of the present invention is mounted with an internal combustion engine (engine), a power storage device and an electric motor that is rotatably driven by electric power from the power storage device, and achieves a high fuel consumption efficiency by optimally distributing driving force generated by the internal combustion engine and that generated by the electric motor. Further, the power storage device mounted on vehicle100is chargeable with electric power from an external power supply (commercial power supply for example).

FIG. 1is a side view of vehicle100according to the first embodiment of the present invention. Referring toFIG. 1, a connector protecting portion (charge port)200is formed in a vehicle body (body)300. Connector protecting portion200is provided with a connector (not shown inFIG. 1) connected to a cable which is used for transmitting electric power supplied from a commercial power supply as well as a lid204for preventing water, dust particles and the like from entering the connector.FIG. 1shows a structure where connector protecting portion200is formed on the left side and the front-wheel side of vehicle body300. The position where connector protecting portion200is formed, however, is not limited to a particular one.

In the body of vehicle100according to the present embodiment, a fuel filler neck (not shown) for supplying fuel which is necessary for operating the internal combustion engine is formed.

FIG. 2is an external view of connector protecting portion200.FIG. 2shows the state where lid204is opened. Referring toFIG. 2, connector protecting portion200includes a housing208that is a depressed portion formed in the vehicle's external surface of body300. Housing208houses a charge connector25. Charge connector25corresponds to “vehicle inlet” defined by the SAE standards.

Lid204is pivotably supported by a support206. A user can thus open and close lid204.

Referring further toFIGS. 3 and 4, a configuration of vehicle100will be described in more detail.

Vehicle100includes a control unit2for controlling operation of vehicle100, a power storage device (BAT)4storing electric power for generating driving force for vehicle100, and a drive unit30that can drive vehicle100by using the electric power stored in power storage device4. Drive unit30includes a converter (CONV)6, a main positive line MPL, a main negative line MNL, a capacitor C, a first inverter (INV1)8-1, a second inverter (INV2)8-2, a motor generator MG1, a motor generator MG2, an internal combustion engine ENG18, and a power split device22.

Power storage device4is an electric power storage element that is configured to be chargeable and dischargeable. Power storage device4is formed, for example, of a secondary battery such as lithium-ion battery or nickel-hydrogen battery, or a power storage element such as electric double layer capacitor.

Converter6makes an interconversion between the input/output voltage of power storage device4and the voltage between main positive line MPL and main negative line MNL. The voltage conversion by converter6is controlled according to switching command PWC from control unit2.

Capacitor C smoothes the voltage between main positive line MPL and main negative line MNL. Inverters8-1,8-2are provided in association with motor generators MG1, MG2respectively. Inverters8-1,8-2are electrically connected, in parallel with each other, to power storage device4. Inverters8-1,8-2make an interconversion between DC (direct current) power and AC (alternating current) power.

AC port210electrically connects electric power line Lp and electric power line ACLp and further electrically connects electric power line Ln and electric power line ACLn, in response to signal S1. Control unit2generates signal S1for controlling the electrical connection between electric power line Lp and electric power line ACLp as well as the electrical connection between electric power line Ln and electric power line ACLn, and outputs the signal to AC port210.

AC port210is connected by electric power lines Lp, Ln to charge connector25. AC port210is further connected by electric power lines ACLp and ACLn to a neutral point N1of motor generator MG1and a neutral point N2of motor generator MG2.

As shown inFIG. 10, motor generators MG1and MG2each include a stator having a U phase coil, a V phase coil and a W phase coil that are Y-connected (star-connected). The point where the Y-connected three coils of each motor generator are commonly connected corresponds to neutral point N1of motor generator MG1or neutral point N2of motor generator MG2.

Referring back toFIG. 3, in the case where power storage device4is charged by external power supply240, the electric power from external power supply240is transmitted to vehicle100by a coupler250. Coupler250includes a plug260, a connector261, a CCID (Charging Circuit Interrupt Device)262, and charge cables263,264. Charge cable264includes electric power lines PSLp, PSLn. Coupler250corresponds to an EVSE (Electric Vehicle Supply Equipment) defined by the SAE standards.

Plug260is connected to a connector241that is electrically coupled to external power supply240. Connector261is connected to charge connector25. Accordingly, electric power lines PSLp, Lp, ACLp are electrically connected and electric power lines PSLn, Ln, ACLn are electrically connected.

Control unit2receives cable connection signal PISW indicating that connector261and charge connector25are connected. Based on the voltage level of cable connection signal PISW, control unit2detects that connector261is connected to charge connector25.

Here, the voltage value and the type (DC or AC) of the electric power supplied from external power supply240are not limited to particular ones. For example, a commercial power supply providing electric power to each household may be used as external power supply240. In the present embodiment, external power supply240is a commercial single-phase AC power supply (with its voltage value of 100 V or 200 V).

CCID262is provided between charge cables263,264. CCID262electrically connects/disconnects charge cable263and charge cable264to/from each other. Further, CCID262is operated by electric power provided from external power supply240in the case where plug260is connected to connector241. CCID262generates pilot signal CPLT and outputs the generated pilot signal CPLT to control unit2.

Between charge connector25and control unit2, a signal line for transmitting pilot signal CPLT and a signal line for transmitting cable connection signal PISW are provided. Control unit2receives pilot signal CPLT and cable connection signal PISW via these signal lines.

The electric power of the external power supply is supplied to neutral points N1, N2of motor generators MG1, MG2, and accordingly the voltage of electric power line PSLp is applied to each phase on the AC side of inverter8-1, and the voltage of electric power line PSLn is applied to each phase on the AC side of inverter8-2. In response to respective switching commands PWM1, PWM2, inverters8-1,8-2perform switching operation. Thus, DC electric power having a predetermined voltage value is supplied from inverters8-1,8-2to main positive line MPL and main negative line MNL.

More specifically, as shown inFIG. 10, inverters8-1,8-2each include three arm circuits corresponding respectively to three phases on the AC side. Each arm circuit includes an upper arm circuit and a lower arm circuit each having at least one switching element.

In inverters8-1,8-2each, the upper arm circuits corresponding to respective phases are all turned on/off together, and the lower arm circuits corresponding to respective phases are also all turned on/off together. Thus, in inverters8-1,8-2each, the three upper arm circuits can be regarded as being in the same switching state (all of the circuits are on or off). Similarly, the three lower arm circuits can be regarded as being in the same switching state. By this switching operation, respective phase voltages can be made equal to each other. Here, such a switching mode is also referred to as zero-phase mode.

FIG. 4shows a zero-phase equivalent circuit of inverters8-1,8-2and motor generators MG1, MG2in the zero-phase mode. Referring toFIG. 4, in the case where inverters8-1,8-2perform the switching operation according to the above-described zero-phase mode, the three upper arm circuits of inverter8-1may be collectively represented as upper arm ARM1p,and the three lower arm circuits of inverter8-1may be collectively represented as lower arm ARM1n.Upper arm ARM1pand lower arm ARM1nare each formed of a switching element TR and a free-wheeling diode D. Similarly, the three upper arm circuits of inverter8-2may be collectively represented as upper arm ARM2pand the three lower arm circuits of inverter8-2may be collectively represented as lower arm ARM2n.

The zero-phase equivalent circuit shown inFIG. 4can be regarded as a single phase inverter that can convert the DC power supplied through main positive line MPL and main negative line MNL into single-phase AC power, and convert single-phase AC power that is input to neutral points N1and N2through electric power lines ACLp, ACLn into DC power.

Specifically, inverters8-1,8-2are controlled so that the zero-phase mode can be implemented, and accordingly inverters8-1,8-2can be operated equivalently as single-phase inverters. Thus, the single-phase AC power supplied from external power supply240can be converted into the DC power, and this DC power can be supplied to main positive line MPL and main negative line MNL. The DC power is used to charge power storage device4.

Referring again toFIG. 3, the configuration of vehicle100will be further described. Internal combustion engine ENG18is operated through combustion of fuel. Motor generator MG1can generate electric power by receiving a part of the motive power from internal combustion engine ENG18. Motor generator MG2operates as an electric motor using the electric power from power storage device (BAT)4.

Internal combustion engine ENG18and motor generators MG1, MG2are mechanically coupled to each other via power split device22. Power split device22is typically formed of a planetary gear train.

When vehicle100is traveling, inverter8-1mainly converts the AC power generated by motor generator MG1into DC power in response to switching command PWM1from control unit2. Inverter8-2converts, in response to switching command PWM2from control unit2, the DC power supplied through main positive line MPL and main negative line MNL into AC power and supplies the AC power to motor generator MG2. Power split device22splits the driving force generated by the operation of internal combustion engine ENG18into two components and delivers the one to motor generator MG1and the other to motor generator MG2.

The driving force delivered from power split device22to motor generator MG1is used for generating electric power. The electric power generated by motor generator MG1is used for charging power storage device4, or used for generating driving force by motor generator MG2. The driving force delivered to motor generator MG2is combined with driving force generated by motor generator MG2to be used for driving drive wheels24.

Here, the number of power storage devices and the capacity of the power storage device are not limited to particular ones. For example, a plurality of power storage devices may be mounted on vehicle100. Thus, in the case where power storage devices4are charged by external power supply240, power storage devices4can be sufficiently charged. In this case, the vehicle can travel by using only the driving force generated by motor generator MG2while keeping internal combustion engine ENG18in the stopped state, namely the vehicle can travel in the so-called EV (Electric Vehicle) mode. For example, a larger quantity of electric power can be stored by increasing the number of power storage devices, so that the vehicle can travel over a longer distance in the EV mode.

Control unit2controls drive unit30so that vehicle100is ready to travel, in response to activation instruction IGON. Specifically, control unit2controls converter6and inverters8-1,8-2based on information from current sensors10,14and voltage sensors12,16. Current sensor10detects current That that is electric current flowing through electric power line PL (electric current input/output to/from power storage device4). Voltage sensor12detects voltage Vbat between electric power lines PL and NL. Current sensor14detects current IDC flowing through main positive line MPL. Voltage sensor16detects voltage VDC between main positive line MPL and main negative line MNL. Control unit2receives respective values of current That and current IDC and respective values of voltage Vbat and voltage VDC and outputs switching commands PWM1, PWM2, PWC.

A vehicle speed detection device32detects speed SV of vehicle100and outputs the detected value of the speed to control unit2.

In the following, CCID262will be described in more detail. When connector261is connected to charge connector25and the potential of pilot signal CPLT decreases to a prescribed value, CCID262causes pilot signal CPLT to oscillate with a prescribed duty (the ratio of the pulse width to the period of oscillation) cycle. This duty cycle is set based on the rated current that can be provided from external power supply240to vehicle100via coupler250.

FIG. 5is a diagram showing a waveform of pilot signal CPLT generated by CCID262shown inFIG. 3. Referring toFIG. 5, pilot signal CPLT oscillates with a prescribed period T. A pulse width Ton of pilot signal CPLT is set based on the rated current that can be provided from external power supply240to vehicle100via coupler250. Control unit2included in vehicle100receives pilot signal CPLT from CCID262. Control unit2obtains information about the rated current from the duty represented by the ratio of pulse width Ton to period T.

The rated current is defined for each charge cable. For charge cables of different types, duties of pilot signal CPLT are different from each other because respective rated currents of the charge cables are different from each other. Control unit2receives pilot signal CPLT transmitted from CCID262via a control pilot line (control line), and detects the duty of the received pilot signal CPLT. Accordingly, control unit2can detect the rated current that can be supplied to vehicle100. In other words, pilot signal CPLT is a supply electric power signal indicating information about the supply electric power provided to vehicle100.

FIG. 6is a diagram illustrating a configuration of CCID262shown inFIG. 3. Referring toFIG. 6, CCID262includes a relay332, a control pilot circuit334, an electromagnetic coil606, and an electrical leakage detector608. Control pilot circuit334includes an oscillator602, a resistor R1and a voltage sensor604.

When connector241and plug260are connected, oscillator602receives electric power provided from external power supply240. Oscillator602is operated by this electric power. Oscillator602outputs a non-oscillating signal when the potential of pilot signal CPLT detected by voltage sensor604is close to a prescribed potential V1(12 V for example), and outputs a signal oscillating at a prescribed frequency (1 kHz for example) and a prescribed duty cycle when the potential of pilot signal CPLT decreases from V1. As described hereinlater, the potential of pilot signal CPLT is changed by changing the resistance value of a resistance circuit included in control unit2.

Control pilot circuit334supplies electric current to electromagnetic coil606when the potential of pilot signal CPLT is close to a prescribed potential V3(6 V for example). Electromagnetic coil606generates an electromagnetic force when supplied with electric current from control pilot circuit334and turns on relay332. When connector261is connected to charge connector25and relay332is turned on, a pair of electric power lines used for supplying charge electric power from external power supply240to the plug-in hybrid vehicle is electrically connected to electric power lines Lp, Ln.

Electrical leakage detector608is provided on the pair of electric power lines used for supplying charge electric power from external power supply240to the plug-in hybrid vehicle, for detecting whether electrical leakage occurs or not. Specifically, electrical leakage detector608detects the state of balance between electric currents flowing in the opposite directions through the pair of electric power lines. When the state of balance is lost, electrical leakage detector608detects occurrence of electrical leakage. When electrical leakage is detected by electrical leakage detector608, power supply to electromagnetic coil606is interrupted and relay332is turned off, which is not particularly shown. The potential of pilot signal CPLT is fixed to a prescribed negative potential (−12 V for example).

Pilot signal CPLT is output from control pilot circuit334to a terminal T1. Terminal T1is connected by control pilot line L1to control unit2. Accordingly, pilot signal CPLT which is output from control pilot circuit334is input to control unit2via control pilot line L1.

Connector261is provided with a switch312. Switch312is connected between a terminal T2and a ground node. Further, terminal T2and control unit2are connected by a signal line L2. When connector261is connected to charge connector25, switch312is turned on. Thus, cable connection signal PISW indicating that connector261is connected to charge connector25is input via signal line L2to control unit2. A ground terminal of control unit2is connected by a ground line L3to the ground node.

Control unit2further receives speed SV of the vehicle detected by vehicle speed detection device32.

A resistor R2is connected between terminals T1, T2. When charge connector25is connected to connector261, switch312is turned on so that terminal T2is connected to the ground node. In contrast, when charge connector25is not connected to connector261, switch312is turned off so that terminal T2is disconnected from the ground node and the potential of terminal T2is set higher than the ground potential. Accordingly, the present embodiment can detect a break of control pilot line L1. In the present embodiment, particularly when vehicle100is not connected to external power supply240, namely charge connector25is not connected to connector261, a break of control pilot line L1can be detected.

Further, in the present embodiment, when charge connector25is connected to connector261, a power-supply-side abnormality can be detected based on whether or not the potential of control pilot line L1changes. Here, “power-supply-side abnormality” means an abnormality in power supply to vehicle100and includes, for example, disconnection between plug260and connector241or failure of power supply from external power supply240.

FIG. 7is a diagram illustrating a configuration of control unit2shown inFIG. 3. Referring toFIG. 7, control unit2includes diodes D1, D2, a resistance circuit502, a voltage generation circuit504, a negative voltage detection circuit506, input buffers508,520, CPUs (Control Processing Units)512,514,522,524, and a sampling control circuit526.

Resistance circuit502includes pull-down resistors R3, R4and switches SW1, SW2. Pull-down resistor R3and switch SW1are connected in series between control pilot line L1through which pilot signal CPLT is transmitted and a vehicle earth518. Pull-down resistor R4and switch SW2are connected in series between control pilot line L1and vehicle earth518, and connected in parallel with series-connected pull-down resistor R3and switch SW1. Switches SW1, SW2are turned on/off in response to a control signal from CPU512.

Resistance circuit502changes the potential of pilot signal CPLT by turning on/off switches SW1, SW2in response to the control signal from CPU512. Specifically, when switch SW1is turned off and switch SW2is turned on in response to the control signal from CPU512, pull-down resistor R4causes the potential of pilot signal CPLT to decrease to a prescribed potential V2(9 V for example). Further, when switch SW1is turned on in response to the control signal from CPU512, pull-down resistors R3, R4cause the potential of pilot signal CPLT to decrease to prescribed potential V3(6 V for example).

Voltage generation circuit504includes a power supply node516, a pull-up resistor R5, a resistor R6, and a diode D3. When connector261is not connected to charge connector25, voltage generation circuit504generates a voltage on control pilot line L1that is determined by voltage division using pull-up resistor R5, resistor R2connected between terminals T1, T2and a pull-down resistor R7.

Negative voltage detection circuit506detects that the potential of pilot signal CPLT is fixed to a prescribed negative potential (−12 V for example) and outputs the result of detection to CPU512. The case where the potential of pilot signal CPLT is fixed to a prescribed negative potential corresponds to the case where electrical leakage is detected by electrical leakage detector608(seeFIG. 6). The method for detecting a negative potential by negative voltage detection circuit506is not limited to a particular one.

Input buffer508receives pilot signal CPLT on control pilot line L1and outputs the received pilot signal CPLT to CPU512.

Voltage generation circuit504receives cable connection signal PISW via signal line L2. Voltage generation circuit504outputs a signal according to cable connection signal PISW. Receiving the signal from voltage generation circuit504, input buffer520outputs the signal to CPU522.

When connector261is connected to charge connector25, switch312is turned on so that the potential of signal line L2becomes the ground level. In contrast, when connector261is not connected to charge connector25, switch312is turned off so that the potential of signal line L2becomes a first potential higher than the ground level. In other words, cable connection signal PISW has an L (logical low) level when connector261is connected to the charge connector and has an H (logical high) level when connector261is not connected to the charge connector.

When cable connection signal PISW has L level, the signal of L level is applied to input buffer520. When cable connection signal PISW has H level, the signal of H level is applied to input buffer520. CPU522determines that connector261is connected to charge connector25when CPU522receives the signal of L level.

When signal line L2is broken, the potential of the signal that is input to input buffer520has a second potential higher than the above-described first potential. When the potential of the signal received from input buffer520is the second potential, CPU522determines that signal line L2is broken.

CPU522remains stopped until started by CPU524. Further, CPU512remains stopped until started by CPU514. CPU524starts CPU522when CPU524detects that connector261is connected to charge connector25. CPU514starts CPU512in response to the start of CPU522.

CPU524controls sampling control circuit526such that sampling control circuit526outputs a control signal used for repeatedly turning on/off a switch SW3. The on-period of switch SW3or the timing at which switch SW3is turned on is not limited to a particular one.

In the case where connector261is not connected to charge connector25, the potential of signal SIN that is input to CPU524is equal to potential B2of a node515when switch SW3is turned on, and equal to potential B1of a node514when switch SW3is turned off. In contrast, in the case where connector261is connected to charge connector25, the potential of signal SIN decreases to the ground level regardless of whether switch SW3is turned on or off. When CPU524detects that the potential of signal SIN is the ground level, CPU524determines that connector261is connected to charge connector25and accordingly starts CPU522.

When CPU522is started by CPU524, CPU522receives a signal from input buffer520. When the signal from input buffer520has L level, CPU522determines that connector261is connected to charge connector25.

CPU514monitors the state of CPU522, and starts CPU512when CPU522is started by CPU524.

When CPU512is started by CPU514, CPU512receives pilot signal CPLT from input buffer508. Further, when CPU512receives from CPU522the result of determination that connector261is connected to charge connector25, CPU512activates a control signal to be output to switch SW2. After this, CPU512detects the rated current that can be supplied from external power supply240to vehicle100, based on pilot signal CPLT that starts oscillating in response to turn-on of switch SW2.

When the rated current is detected and preparation for charging power storage device4by external power supply240is completed, CPU512further activates a control signal to be output to switch SW1and sends signal S1to AC port210shown inFIG. 3. Accordingly, as shown inFIG. 3, the AC power from external power supply240is provided to neutral point N1of motor generator MG1and neutral point N2of motor generator MG2(both are not shown), and charge control of power storage device4is performed.

CPU512determines, in the state where connector261is connected to charge connector25, whether or not an abnormality occurs in supply of electric power from the power supply side. Based on whether or not the potential of pilot signal CPLT changes, CPU512determines whether or not an abnormality occurs in supply of electric power, which will be described hereinlater in detail.

CPU512determines, in the state where connector261is not connected to charge connector25, whether or not control pilot line L1is broken. Specifically, CPU512determines whether or not control pilot line L1is broken in the case where speed SV of vehicle100as detected by vehicle speed detection device32(seeFIG. 3) is different from zero.

The case where speed SV is different from zero refers to the case where vehicle100is traveling. When vehicle100is charged by external power supply240, it is considered that vehicle100is stopped. In other words, when vehicle100is traveling, it is considered that vehicle100is not connected to an external power supply. Therefore, in the case where speed SV is larger than zero, CPU512determines whether or not control pilot line L1is broken. In this way, a break of a line can be accurately detected.

As long as the conditions that CPU512is started and connector261is not connected to charge connector25are satisfied, CPU512can detect a break of control pilot line L1. In the present embodiment, a break of the control pilot line is detected while the vehicle is traveling. However, as long as the above-described conditions are satisfied, the timing at which CPU512detects a break of control pilot line L1is not limited to a particular one.

CPU512determines, under the condition that connector261is connected to charge connector25, whether or not an abnormality occurs on the power supply side, and determines, under the condition that connector261is not connected to charge connector25, whether or not control pilot line L1is broken. In this way, in the present embodiment, a break of control pilot line L1and an abnormality on the power supply side can be distinguished from each other.

In the following, a description will be given of detection of a break of control pilot line L1by CPU512. Pull-up resistor R5, resistor R2and pull-down resistor R7form a voltage divider circuit provided between power supply node516and vehicle earth518. When connector261is not connected to charge connector25and control pilot line L1is not broken, a voltage determined by voltage division using pull-up resistor R5, resistor R2and pull-down resistor R7is applied to control pilot line L1. Accordingly, the potential of control pilot line L1is higher than the ground potential (vehicle earth potential). Namely, the potential of control pilot line L1has H level.

In contrast, when control pilot line L1is broken, the potential generated on control pilot line L1is substantially the ground level. Namely, the potential of control pilot line L1has L level.

More specifically, when vehicle100is connected to coupler250, the potential of terminal T2(one end of resistor R2) is set to the vehicle earth potential by switch312. In contrast, when vehicle100is not connected to coupler250, switch312disconnects terminal T2from the vehicle earth potential. When vehicle100is not connected to coupler250, voltage generation circuit504sets (pulls up) the potential of terminal T2to a potential higher than the vehicle earth potential.

Thus, the potential level of control pilot line L1in the case where control pilot line L1is normal and the potential level of control pilot line L1in the case where control pilot line L1is broken are different from each other. Therefore, a break of control pilot line L1can be detected. CPU512determines that control pilot line L1is broken when the potential of control pilot line L1has L level, and determines that control pilot line L1is normal when the potential of control pilot line L1has H level.

Preferably, the resistance value of resistor R2is set to a value that does not influence the change of the potential of pilot signal CPLT in resistance circuit502. In order to set potentials V1to V3to 12 V, 9 V and 6 V respectively, respective resistance values of pull-down resistors R3, R4are assumed to be 1.3 (kΩ) and 2.74 (kΩ) respectively. The resistance value of resistor R2is set to a value (e.g. approximately 100 kΩ) sufficiently larger than these resistance values for example.

FIG. 8is a timing chart of pilot signal CPLT and switches SW1, SW2when charging is started. Referring toFIGS. 6 to 8, plug260of coupler250is connected to connector241of external power supply240at time t1. Accordingly, control pilot circuit334receiving electric power from external power supply240generates pilot signal CPLT.

At this time, connector261of coupler250is not connected to charge connector25on vehicle100side. Therefore, the potential of pilot signal CPLT is V1(12 V for example) and pilot signal CPLT is in the non-oscillating state.

At time t2, connector261is connected to charge connector25. Based on cable connection signal PISW, connection of connector261and charge connector25is detected. Accordingly, switch SW2is turned on. When switch SW2is turned on, pull-down resistor R3of resistance circuit502causes the potential of pilot signal CPLT to decrease to V2(9 V for example).

The potential of pilot signal CPLT decreases to V2, and control pilot circuit334causes pilot signal CPLT to oscillate at time t3. Then, based on the duty of pilot signal CPLT, CPU512detects the rated current and preparation for charge control is made. When the preparation for charge control is completed, switch SW1is turned on at time t4. When switch SW1is turned on, pull-down resistor R3of resistance circuit502causes the potential of pilot signal CPLT to further decrease to V3(6 V for example).

When the potential of pilot signal CPLT decreases to V3, electric current is supplied from control pilot circuit334to electromagnetic coil606and relay332of CCID330is turned on. After this, AC port210is turned on and power storage device4is charged.

The description above relates to a change of pilot signal CPLT in the case where the supply of electric power from the power supply side is normal. When an abnormality occurs in supply of electric power from the power supply side such as power failure or disconnection of external power supply240and connector261, the potential of control pilot line L1remains 0 V because switch312is turned on and terminal T1is connected via resistor R2and terminal T2to the switch.

Therefore, CPU512determines that an abnormality occurs in supply of electric power to be provided to the vehicle in the case where the potential of control pilot line L1remains 0 V for a predetermined period of time from the time when connector261is connected to charge connector25. In contrast, CPU512determines that electric power is normally supplied to the vehicle in the case where connector261is connected to charge connector25and the potential of control pilot line L1changes.

FIG. 9is a diagram showing pilot signal CPLT when a break of control pilot line L1is detected. Referring toFIGS. 9 and 7, it is supposed that connector261of coupler250is detached from charge connector25on the vehicle side before time t11. When the vehicle starts traveling at time t11so that vehicle speed SV is not zero, CPU512determines whether or not a break of control pilot line L1occurs.

If control pilot line L1is not broken, the potential of pilot signal CPLT does not decrease and is kept higher than 0 V. Namely, pilot signal CPLT is kept at H level. In contrast, if control pilot line L1is broken, the potential of pilot signal CPLT decreases to the ground level (i.e., the vehicle earth potential and substantially 0 V) and thus pilot signal CPLT becomes L level. Therefore, CPU512can detect a break of control pilot line L1by detecting the decrease of pilot signal CPLT to L level.

In the present embodiment, vehicle100may further include a detection device used for detecting an open/close state of lid204. In this case, CPU512may determine whether or not control pilot line L1is broken in the case where the detection device detects the closed state of lid204and speed SV of the vehicle is different from zero. Since the detection of a break is carried out under the conditions that lid204is in the closed state and vehicle speed SV is not zero, it can be ensured that detection of a break is prevented while charging is performed using pilot signal CPLT for charge control. Thus, a break of the line can be accurately detected.

Second Embodiment

FIG. 11is a schematic configuration diagram of a vehicle100A according to a second embodiment of the present invention. Referring toFIGS. 11 and 3, vehicle100A differs from vehicle100in that vehicle100A includes a charger35. Further, vehicle100A differs from vehicle100in that vehicle100A does not include AC port210and electric power lines ACLp, ACLn. Charger35is connected to power storage device4in parallel with drive unit30. Charger35is connected by electric power lines Lp, Ln to charge connector25, and connected by main positive line MPL and main negative line MNL to power storage device4.

When plug260is connected to connector241and connector261is connected to charge connector25(vehicle inlet), electric power (AC power for example) from external power supply240is supplied via coupler250and electric power lines Lp, Ln to charger35. Charger35supplies to power storage device4the electric power that is input via electric power lines Lp, Ln, and accordingly charges power storage device4. In the case for example where charger35receives AC power via electric power lines Lp, Ln, the charger converts the AC power into DC power and outputs the DC power to main positive line MPL and main negative line MNL. The DC power is used to charge power storage device4. Charger35performs this electric power conversion according to signal CHG from control unit2.

Control unit2receives cable connection signal PISW indicating that connector261and charge connector25are connected. Control unit2detects that connector261is connected to charge connector25based on the voltage level of cable connection signal PISW. CCID262is operated by electric power provided from external power supply240when plug260is connected to connector241. CCID262then generates pilot signal CPLT and outputs the generated pilot signal CPLT to control unit2. Between charge connector25and control unit2, a signal line used for transmitting pilot signal CPLT and a signal line used for transmitting cable connection signal PISW are provided (not shown). Control unit2receives pilot signal CPLT and cable connection signal PISW via these signal lines.

Other components of vehicle100A are similar to corresponding components of vehicle100and therefore, the further description thereof will not be repeated.

The configuration and operation of CCID262are similar to those in the first embodiment. Further, the configuration and operation of control unit2are similar to those in the first embodiment. Therefore, the second embodiment can achieve the same effects as those of the first embodiment. Specifically, a break of control pilot line L1can be detected in the second embodiment. In the present embodiment, particularly when vehicle100is not connected to external power supply240, namely charge connector25is not connected to connector261, a break of control pilot line L1can be detected.

Moreover, in the second embodiment, an abnormality on the power supply side can be detected under the condition that charge connector25is connected to connector261.

In the first embodiment, CPU512sends signal S1to AC port210under the conditions that CPU512detects the rated current and preparation for charging power storage device4from external power supply240is completed. In contrast, in the second embodiment, CPU512sends signal CHG to charger35to operate charger35under the above-described conditions.