Electronic control unit and power supply system

A power relay unit includes a high potential side relay connected so that an anode of a parasitic diode is on a high potential side and a cathode is on a low potential side, and a low potential side relay connected in series with a low potential side of the high potential side relay so that a cathode of a parasitic diode is on a high potential side and an anode is on a low potential side. A relay-to-relay connection line connects an intermediate point between the first high potential side relay and the first low potential side relay and an intermediate point between the second high potential side relay and the second low potential side relay. A control unit controls an on/off operation of the first high potential side relay based on a first supply voltage, a second supply voltage, and a relay intermediate voltage.

TECHNICAL FIELD

The present disclosure relates to an electronic control unit and a power supply system.

BACKGROUND

Conventionally, a steering device including an ECU that operates by being supplied with electric power from two batteries is known.

SUMMARY

An object of the present disclosure is to provide an electronic control unit and a power supply system that can continue to operate appropriately even if an abnormality occurs in one of the power supplies.

An electronic control unit of the present disclosure includes a first power supply relay unit, a second power supply relay unit, a relay-to-relay connection line, a first relay control circuit, a second relay control circuit, and a control unit.

The first power supply relay unit includes a first high potential side relay, which is connected so that an anode of a parasitic diode is on a high potential side and a cathode is on a low potential side, and a first low potential side relay, which is connected in series with the low potential side of the first high potential side relay so that a cathode of a parasitic diode is on the high potential side and an anode is on the low potential side, and is connected to a first external power source.

The second power supply relay unit includes a second high potential side relay, which is connected so that an anode of a parasitic diode is on a high potential side and a cathode is on a low potential side, and a second low potential side relay, which is connected in series with the low potential side of the second high potential side relay so that a cathode of a parasitic diode is on the high potential side and an anode is on the low potential side, and is connected to a second external power source different from the first external power source.

The relay-to-relay connection line connects an intermediate point between the first high potential side relay and the first low potential side relay and an intermediate point between the second high potential side relay and the second low potential side relay. The first relay control circuit includes a first relay driver that drives the first high potential side relay, a first upper monitor circuit that monitors a first supply voltage on the high potential side of the first high potential side relay, and a first lower monitor circuit that monitors a relay intermediate voltage, which is a voltage of the relay-to-relay connection line on the low potential side of the first high potential side relay.

The second relay control circuit includes a second relay driver that drives the second high potential side relay, a second upper monitor circuit that monitors a second supply voltage on the high potential side of the second high potential side relay, and a second lower monitor circuit that monitors a relay intermediate voltage on the low potential side of the high potential side of the second high potential side relay.

The control unit controls an on/off operation of the first high potential side relay and the second high potential side relay based on the first supply voltage, the second supply voltage, and the relay intermediate voltage. As a result, even if an abnormality occurs in the first external power supply or the second external power supply, the operation can be continued appropriately.

DETAILED DESCRIPTION

In an assumable example, a steering device including an ECU that operates by being supplied with electric power from two batteries is known. For example, two ECUs are provided with a power relay for switching on/off of power supply to a drive circuit of an own system and an auxiliary power supply relay for switching on/off of power supply to a drive circuit of another system.

In a circuit configuration of the example, when a regenerative power is large, there is a possibility that power exceeding an allowable amount of a battery is supplied depending on an on/off timing of an auxiliary power relay. In order to avoid excessive power regeneration to the battery side, if the power supply is temporarily turned off before turning on the auxiliary power relay, the power supply to the microcomputer is also cut off, so it is necessary to take measures against temporary power cutoff. An object of the present disclosure is to provide an electronic control unit and a power supply system that can continue to operate appropriately even if an abnormality occurs in one of the power supplies.

An electronic control unit of the present disclosure includes a first power supply relay unit, a second power supply relay unit, a relay-to-relay connection line, a first relay control circuit, a second relay control circuit, and a control unit.

The first power supply relay unit includes a first high potential side relay, which is connected so that an anode of a parasitic diode is on a high potential side and a cathode is on a low potential side, and a first low potential side relay, which is connected in series with the low potential side of the first high potential side relay so that a cathode of a parasitic diode is on the high potential side and an anode is on the low potential side, and is connected to a first external power source.

The second power supply relay unit includes a second high potential side relay, which is connected so that an anode of a parasitic diode is on a high potential side and a cathode is on a low potential side, and a second low potential side relay, which is connected in series with the low potential side of the second high potential side relay so that a cathode of a parasitic diode is on the high potential side and an anode is on the low potential side, and is connected to a second external power source different from the first external power source.

The relay-to-relay connection line connects an intermediate point between the first high potential side relay and the first low potential side relay and an intermediate point between the second high potential side relay and the second low potential side relay. The first relay control circuit includes a first relay driver that drives the first high potential side relay, a first upper monitor circuit that monitors a first supply voltage on the high potential side of the first high potential side relay, and a first lower monitor circuit that monitors a relay intermediate voltage, which is a voltage of the relay-to-relay connection line on the low potential side of the first high potential side relay.

The second relay control circuit includes a second relay driver that drives the second high potential side relay, a second upper monitor circuit that monitors a second supply voltage on the high potential side of the second high potential side relay, and a second lower monitor circuit that monitors a relay intermediate voltage on the low potential side of the high potential side of the second high potential side relay.

The control unit controls an on/off operation of the first high potential side relay and the second high potential side relay based on the first supply voltage, the second supply voltage, and the relay intermediate voltage. As a result, even if an abnormality occurs in the first external power supply or the second external power supply, the operation can be continued appropriately.

One Embodiment

Hereinafter, an electronic control unit according to the present disclosure will be described with reference to the drawings. The electronic control unit according to one embodiment is shown inFIGS.1to9. As shown inFIG.1, an ECU10as an electronic control unit is applied to, for example, an electric power steering device8for assisting a steering operation of a vehicle.FIG.1shows a configuration of a steering system90including the electric power steering device8. The steering system90includes a steering wheel91as a steering member, a steering shaft92, a pinion gear96, a rack shaft97, wheels98, the electric power steering device8, and the like.

The steering wheel91is connected to the steering shaft92. A torque sensor94is provided on the steering shaft92to detect a steering torque. The torque sensor94has a first sensor unit194and a second sensor unit294, each of which is capable of detecting its own failure. The pinion gear96is provided at an axial end of the steering shaft92. The pinion gear96meshes with the rack shaft97. The pair of wheels98is connected to both ends of the rack shaft97through tie rods or the like.

When a driver rotates the steering wheel91, the steering shaft92connected to the steering wheel91rotates. A rotational movement of the steering shaft92is converted into a linear movement of the rack shaft97by the pinion gear96. The pair of wheels98is steered to an angle corresponding to the displacement amount of the rack shaft97.

The electric power steering device8includes a drive device40, a reduction gear89, and the like. The drive device40includes a motor80, an ECU10, and the like. The reduction gear89, which is one of a power transmission unit, decelerates the rotation of the motor80and transmits it to the steering shaft92. In other words, the electric power steering device8according to the present embodiment is a so-called “column assist type”, but may be a so-called “rack assist type” which transmits the rotation of the motor80to the rack shaft97. In the present embodiment, the steering shaft92corresponds to a “drive target”.

As shown inFIG.2toFIG.4, the motor80outputs a whole or a part of a torque required for a steering operation. The motor80is driven by electric power supplied from batteries191and291provided as an external power source in order to rotate the reduction gear89in forward and reverse directions. The motor80is a three-phase brushless motor, but may be a motor other than the three-phase brushless motor.

The motor80has a first motor winding180and a second motor winding280as a winding set. The motor windings180and280have the same electrical characteristics and are wound about a stator840(seeFIG.2) with electrical angles changed from each other by 30 degrees. Correspondingly, phase currents are controlled to be supplied to the motor windings180and280such that the phase currents have a phase difference φ of 30 degrees. By optimizing the current supply phase difference, the output torque can be improved. In addition, sixth-order torque ripple can be reduced, and noise and vibration can be reduced. In addition, since heat is also distributed and averaged by distributing the current, it is possible to reduce temperature-dependent system errors such as a detection value and torque of each sensor and increase the amount of current that is allowed to be supplied. The motor windings180and280do not have to be cancel windings, and may have different electrical characteristics.

Hereinafter, a combination of a first inverter120and a first control unit170and the like, which are related to the driving control for the first motor winding180, is referred to as a first system L1, and a combination of a second inverter220and a second control unit270and the like, which are related to the driving control for the second motor winding280, is referred to as a second system L2. The configuration related to the first system L1is basically indicated with reference numerals of 100, and the configuration related to the second system L2is basically indicated with reference numerals of 200. Further, in the first system L1and the second system L2, similar or similar configurations are numbered so that the last two digits are the same, and the description relating to the configuration of the second system L2and the like is omitted as appropriate. For the other configuration described below, the term “first” is indicated with a suffix “1,” and the term “second” is indicated with a suffix “2.”

In the drive device40, the ECU10is integrally provided on one side in the axial direction of the motor80in a machine-electronics integrated type. The motor80and the ECU10may alternatively be provided separately. The ECU10is positioned coaxially with an axis Ax of a shaft870on the side opposite to the output shaft of the motor80. The ECU10may alternatively be provided on the output shaft side of the motor80. With the electromechanical integrated type, the ECU10and the motor80can be efficiently placed in a vehicle having a limited mounting space.

The motor80includes the stator840, a rotor860and a housing830which houses the stator840and the rotor860therein. The stator840is fixed to the housing830and the motor windings180and280are wound thereon. The rotor860is provided radially inward of the stator840and rotatable relative to the stator840.

The shaft870is fitted firmly in the rotor860to rotate integrally with the rotor860. The shaft870is rotatably supported by the housing830through bearings835and836. The end portion of the shaft870on the ECU10side protrudes from the housing830toward the ECU10. A magnet875is provided at the axial end of the shaft870on the ECU10side. A center of the magnet875is arranged on the axis Ax.

The housing830has a bottomed cylindrical case834, which has a rear end frame837, and a front end frame838provided on an open side of the case834. The case834and the front end frame838are fastened to each other by bolts or the like. Lead wire insertion holes839are formed in the rear end frame837. Lead wires185and285connected to each phase of the motor windings180and280are inserted through the lead wire insertion holes839. The lead wires185and285are taken out from the lead wire insertion holes839to the ECU10side and connected to a substrate470.

The ECU10includes a cover460and a heat sink465fixed to the cover460in addition to the substrate470fixed to the heat sink465. The ECU10further includes various electronic components and the like mounted on the substrate470. The cover460protects the electronic components from external impacts and prevents dust, water or the like from entering into the ECU10. In the cover460, a cover main body461and a connector member462are integrally formed. The connector member462may be separate from the cover main body461. Terminals463of the connector member462are connected to the substrate470via a wiring (not shown) or the like. The number of connectors and the number of terminals may be changed in correspondence to the number of signals and the like. The connector member462is provided at the end portion in the axial direction of the drive device40and is open on the side opposite to the motor80.

The substrate470is, for example, a printed circuit board, and is positioned to face the rear end frame837. Two systems of electronic components are independently mounted on the substrate470for each system. According to the present embodiment, the electronic components are mounted on one substrate470. The electronic components may alternatively be mounted on plural substrates.

Of the two principal surfaces of the substrate470, one surface on the side of the motor80is referred to as a motor-side surface471and the other surface opposite from the motor80is referred to as a cover-side surface472. As shown inFIG.3, switching elements121to126configuring the first inverter120, switching elements221to226configuring the second inverter220, rotation angle sensors134,234, custom ICs171,271and the like are mounted on the motor-side surface471.

The custom ICs171,271are provided with booster circuits160,260(seeFIG.4), an amplifier circuit, a predriver, and the like. A boost voltage of the booster circuits160and260is higher than a supply voltages Vb1and Vb2, and is used as a gate voltage of the switching elements121to123and221to223on a high potential side. The rotation angle sensors134and234are mounted at positions facing the magnet875to be able to detect a change in the magnetic field caused by the rotation of the magnet875.

On the cover-side surface472, inductors145and245, capacitors146,147,246, and247, computers forming the control units170and270, and the like are mounted. InFIG.3, reference numerals170and270are assigned to the computers provided as the control units170and270, respectively. Although not shown inFIG.3, the motor relays127to129,227to229, current detection elements131to133,231to233, relays141,142,241, and242and the like are also mounted on the motor-side surface471or on the cover-side surface472.

As shown inFIGS.4and5, the ECU10includes inverters120,220, power relay units140,240, control units170,270, and the like. The energization of the first motor winding180is controlled by the first control unit170, and the energization of the second motor winding280is controlled by the second control unit270. In the present embodiment, the first system L1and the second system L2are provided independently of each other in a completely redundant configuration.

Each of the control circuits170and270is mainly composed of a microcomputer and the like, and internally includes, although not shown in the figure, a CPU, a ROM, a RAM, an I/O, a bus line for connecting these components, and the like. Each process executed by each of the control circuits170and270may be a software process or may be a hardware process. The software process may be implemented by causing the CPU to execute a program. The program may be stored beforehand in a memory device such as a ROM, that is, in a computer-readable, non-transitory, tangible storage medium. The hardware process may be implemented by a special purpose electronic circuit. In the figure, the control units170and270are referred to as “computers” as appropriate.

The first inverter120is a three-phase inverter, and the first switching elements121to126are connected in a bridge manner. The switching elements121to123are connected to the high potential side, and the switching elements124to126are connected to the low potential side. A connection point of the paired μ-phase switching elements121and124is connected to one end of a first U-phase coil181. A connection point of the paired V-phase switching elements122and125is connected to one end of a first V-phase coil182. A connection point of the paired W-phase switching elements123and126is connected to one end of a first W-phase coil183. The other ends of the coils181to183are connected to one another. On the low potential side of the switching elements124to126, a first current detection unit130for detecting the current of the coils181to183is provided. The first current detection unit130includes current detection elements131to133.

The second inverter220is a three-phase inverter, and the second switching elements221to226are bridge-connected. The switching elements221to223are connected to the high potential side, and the switching elements224to226are connected to the low potential side. A connection point of the paired U-phase switching elements221and224is connected to one end of a second U-phase coil281. A connection point of the paired V-phase switching elements222and225is connected to one end of a first V-phase coil282. A connection point of the paired W-phase switching elements223and226is connected to one end of a first W-phase coil283. The other ends of the coils281to283are connected to one another. On the low potential side of the switching elements224to226, a second current detection unit230for detecting the current of the coils281to283is provided. The second current detection unit230is provided with current detection elements231to233. Although the current detection elements131to133and231to233of the present embodiment are shunt resistors, other elements such as Hall elements may be used.

The first motor relays127to129are provided between the first inverter120and the first motor winding180, and are provided to be able to connect and disconnect the first inverter120and the first motor winding180. The motor relay127of the U-phase is provided between the connection point of switching elements121and124and the U-phase coil181, and a motor relay128of the V-phase is provided between the connection point of switching elements122and125and the V-phase coil182. The motor relay129of the W-phase is provided between the connection point of the switching elements123and126and the W-phase coil183.

The second motor relays227to229are provided between the second inverter220and the second motor winding280, and are provided to be able to connect and disconnect the second inverter220and the second motor winding280. The motor relay227of the U-phase is provided between the connection point of switching elements221and224and the U-phase coil281. The motor relay228of the V-phase is provided between the connection point of switching elements222and225and the V-phase coil282. The motor relay229of the W-phase is provided between the connection point of the switching elements223and226and the W-phase coil283.

A first power supply relay unit140is provided in a high potential side wiring Lp1that connects a positive electrode of the first battery191and a high potential side of the first inverter120. The first power supply relay unit140has a first power supply relay141and a first reverse connection protection relay142. In the present embodiment, the relays141and142are MOSFETs and have a parasitic diode. Therefore, the two elements are connected in series so that the parasitic diodes of the relays141and142are oriented in opposite directions. Thereby, even when the first battery191is erroneously connected in the reverse direction, it is possible to prevent a reverse current from flowing. Details of the power relay units140and240will be described later.

The on/off operation of the first switching elements121to126, the first motor relays127to129, the power supply relay141, and the reverse connection protection relay142is controlled based on the control signal from the first control unit170. The on/off operation of the second switching elements221to226, the second motor relays227to229, the power supply relay241and the reverse connection protection relay242is controlled based on the control signal from the second control unit270. In addition, in order to avoid complication, some control lines are omitted in the figure.

The inductor145is provided between the first battery191and the first power supply relay unit140. In the capacitor146, a positive electrode is connected between the first battery191and the inductor145, and the negative electrode is connected to the common ground Gc. The inductor145and the capacitor146form a filter circuit to reduce noise transmitted from other devices sharing the first battery191and reduce noise transmitted from the drive device40to other devices sharing the first battery191. In the capacitor147, a positive electrode is connected between the power relay unit140and the first inverter120, and the negative electrode is connected to the common ground Gc. In a Zener diode148(seeFIG.5), a cathode is connected between the power relay unit140and the first inverter120, and an anode is connected to the common ground Gc. The capacitor147and the Zener diode148smooth the power supplied to the first inverter120.

A second inverter220is connected to the second motor winding280, and electric power is supplied to the second motor winding280from the second battery291via the second inverter220. The second inverter220has switching elements221to226. On the low potential side of the second inverter220, the second current detection unit230having current detection elements231to233is provided. Further, motor relays236to238are provided between the second inverter220and the second motor winding280.

A second power supply relay unit240is provided in a high potential side wiring Lp2that connects a positive electrode of the second battery291and a high potential side of the second inverter220. The inductor245is provided between the second battery291and the second power supply relay unit240. In the capacitor246, a positive electrode is connected between the second battery291and the inductor245, and a negative electrode is connected to the common ground Gc. Further, in the capacitor247, a positive electrode is connected between the power relay unit240and the second inverter220, and a negative electrode is connected to the common ground Gc. In a Zener diode248(seeFIG.5), a cathode is connected between the power relay unit240and the second inverter220, and an anode is connected to the common ground Gc. The details of the functions of each component are the same as those of the first system. InFIG.5, the battery terminal of the first system L1is described as B1, the ground terminal is described as G1, the battery terminal of the second system L2is described as B2, and the ground terminal is described as G2.

As shown inFIG.5, the first power supply relay141and the first reverse connection protection relay142have a “common drain” configuration, and are connected so that the drain is located inside and the source is located outside, and the parasitic diode has the anode located outside and the cathode located inside. Similarly, the second power supply relay241and the second reverse connection protection relay242have a “common drain” configuration and are connected so that the drain is located inside and the source is located outside, and the parasitic diode has the anode located outside and the cathode located inside. By adopting the common drain configuration, a lead frame and a chip are shared, and by separating the source by the chip, it is possible to make the size smaller than a common source configuration.

In the present embodiment, the first reverse connection protection relay142is provided on the first battery191side, and the first power supply relay141is provided on a first system circuit C1side. Further, the second reverse connection protection relay242is provided on the second battery291side, and the second power supply relay241is provided on a second system circuit C2side. The first system circuit C1includes a configuration of a first inverter120and a first control unit170connected to a downstream side of the first power supply relay unit140, but for the sake of explanation, the first control unit170and a first monitoring circuit173are described as blocks separate from the first system circuit C1inFIG.5. The same applies to the second system circuit C2.

In the present embodiment, an intermediate point M1between the first power supply relay141and the first reverse connection protection relay142and an intermediate point M2between the second power supply relay241and the second reverse connection protection relay242are connected by a relay-to-relay connection line300. Therefore, a relay intermediate voltage Vbc becomes the same in the systems L1and L2.

A first power supply relay control circuit150is provided corresponding to the first power supply relay141, and a second power supply relay control circuit250is provided corresponding to the second power supply relay241. The first power supply relay control circuit150is provided with a first power supply relay driver151and voltage monitor circuits152and153. The second power supply relay control circuit250is provided with a second power supply relay driver251and voltage monitor circuits252and253.

The first power supply relay driver151switches on/off of the first power supply relay141by outputting a gate signal to the first power supply relay141based on a control signal from the first control unit170. The second power supply relay driver251switches on/off of the second power supply relay241by outputting a gate signal to the second power supply relay241based on a control signal from the second control unit270.

The voltage monitor circuits152,153,252, and253are, for example, voltage dividing resistors and the like. The voltage monitor circuit152detects a relay intermediate voltage Vbc and outputs it to the first control unit170, and the voltage monitor circuit153detects a post-relay voltage Vr1and outputs it to the first monitoring circuit173. The voltage monitor circuit252detects the relay intermediate voltage Vbc and outputs it to the second control unit270, and the voltage monitor circuit253detects a post-relay voltage Vr2and outputs it to the second monitoring circuit273.

A first supply regeneration control circuit155is provided corresponding to the first reverse connection protection relay142, and a second supply regeneration control circuit255is provided corresponding to the second reverse connection protection relay242. The first supply regeneration control circuit155is provided with a first reverse connection protection relay driver156and voltage monitor circuits157and158. The second supply regeneration control circuit255is provided with a second reverse connection protection relay driver256and voltage monitor circuits257and258.

The first reverse connection protection relay driver156switches on/off of the first reverse connection protection relay142by outputting a gate signal to the first reverse connection protection relay142based on the control signal from the first control unit170. The second reverse connection protection relay driver256switches on/off of the second reverse connection protection relay242by outputting a gate signal to the second reverse connection protection relay242based on the control signal from the second control unit270.

The voltage monitor circuits157,158,257, and258are, for example, voltage dividing resistors. The voltage monitor circuit157detects the first supply voltage Vb1and outputs it to the first control unit170, and the voltage monitor circuit158detects the relay intermediate voltage Vbc and outputs it to the first control unit170. The voltage monitor circuit257detects the second supply voltage Vb2and outputs it to the second control unit270, and the voltage monitor circuit258detects the relay intermediate voltage Vbc and outputs it to the second control unit270. The first supply voltage Vb1is the voltage supplied from the first battery terminal B1connected to the first battery191and the second supply voltage Vb2is the voltage supplied from the second battery terminal B2connected to the second battery291.

The booster circuits160and260are connected to the relay-to-relay connection line300. Since it is sufficient that one of the booster circuits160and260is connected to the relay-to-relay connection line300, the booster circuit160of the first system L1will be described below assuming that it is connected to the relay-to-relay connection line300. Further, regarding a boost voltage of the booster circuit160, “1” indicating the system is omitted, and the boost voltage Vu is simply used.

The booster circuit160is connected to the relay-to-relay connection line300via a booster switch161and a resistor162. The opening and closing of the booster switch161is controlled by the first control unit170, and the connection and disconnection between the booster circuit160and the relay-to-relay connection line300can be switched. The booster switch161may be a semiconductor relay or a mechanical relay. A resistance value of the resistor162is set so as to limit the current from the booster circuit160to the relay-to-relay connection line300when the booster switch161is closed. The booster switch161is turned on at the time of initial check and when the internal voltage drops. Details of the initial check will be described later.

In the present embodiment, the parasitic diodes of the reverse connection protection relays142and242provided on the battery191and291sides are provided so as to allow the current from the high potential side to the low potential side. The intermediate point M1of the relays141and142and the intermediate point M2of the relays241and242are connected by the relay-to-relay connection line300. As a result, even if a power supply abnormality such as a voltage drop occurs in the first system L1, it is possible to supply power to the first system L1via the relay-to-relay connection line300from the second battery291without stopping the first system circuit C1and the second system circuit C2. Further, even if a power supply abnormality such as a voltage drop occurs in the second system L2, it is possible to supply power to the second system L2via the relay-to-relay connection line300from the first battery191without stopping the first system circuit C1and the second system circuit C2. Here, the power supply abnormality of the first system L1is not limited to the abnormality of the first battery191itself, but also includes a wiring abnormality and the like. The same applies to the power supply abnormality of the second system L2.

A voltage drop determination process of the present embodiment will be described with reference to the flowchart ofFIG.6. This process is executed by the control units170and270at a predetermined cycle when a start switch of the vehicle such as a ignition switch is turned on. Necessary information is shared by communication between the control units170and270. Hereinafter, “step” in step S101is omitted, and is simply referred to as a symbol “S.” Further, the supply voltages Vb1and Vb2within a normal range are supplied to both the systems L1and L2, and the power supply relays141and241are turned on.

In S101, the control units170and270determine whether or not a voltage drop has occurred. In the present embodiment, if an equation (1) is satisfied, it is determined that a voltage drop has occurred in the first system L1, and if an equation (2) is established, it is determined that a voltage drop is occurred in the second system L2. Vth1and Vth2in the equation are voltage drop determination values and are set according to a drop voltage of the reverse connection protection relays142and242.
Vbc−Vth1>Vb1  (1)
Vbc−Vth2>Vb2  (2)
When it is determined that no voltage drop has occurred in the systems L1and L2(S101: NO), the process after S102is skipped. When it is determined that a voltage drop has occurred in any of the systems L1and L2(S101: YES), the process proceeds to S102. Hereinafter, the system in which the voltage drop occurs is referred to as a voltage drop system, and the system in which the voltage drop does not occur is referred to as a normal system.

In S102, the control units170and270turn off the reverse connection protection relays142and242of the voltage drop system. That is, when the voltage drop occurs in the first system L1, the reverse connection protection relay142is turned off, and when the voltage drop occurs in the second system L2, the reverse connection protection relay242is turned off. As a result, a power supply of the voltage drop system is cut off. Power is supplied to the voltage drop system from the normal system via the relay-to-relay connection line300without interrupting the power supply.

In S103, the control units170and270determine whether or not the state in which the voltage drop has occurred has passed an abnormality determination time Xth or more in the voltage drop system. In the present embodiment, when the state in which an equation (3) is established continues for the abnormality determination time Xth or more, the abnormality is determined. Vthe in the equation (3) is arbitrarily set according to a value allowed as a voltage drop. Further, #in the equation indicates a system, and #is “1” if the voltage drop system is the first system L1and #is “2” if the voltage drop system is the second system L2.
(Vbc−Vth#)−Vb#>Vthe  (3)

When it is determined that the state in which the voltage drop occurs is less than the abnormality judgment time Xth (S103: NO), the reverse connection protection relay of the voltage drop system is continuously turned off, and the power supply from the normal system to both systems is continued. When it is determined that the state in which the voltage drop has occurred has passed the abnormality determination time Xth or more (S103: YES), the process proceeds to S104.

In S104, the control units170and270determine the power supply abnormality of the voltage drop system, and warn the user that the power supply abnormality has occurred, for example, by lighting a warning lamp of an instrument panel. A warning method may be a method other than lighting the warning light, such as voice. This warning encourages users to bring vehicle to dealers and repair shops.

In the present embodiment, when a voltage drop occurs in one system, power is supplied from the normal system to both systems by turning off the reverse connection protection relay of the voltage drop system. Here, when a large amount of regenerative power is generated, if the power exceeding the allowable amount is supplied to the power supply system of the normal system, the battery of the normal system may be destroyed. Therefore, in the present embodiment, the circuit is protected by controlling the on/off of the reverse connection protection relays142and242according to the relay intermediate voltage Vbc.

A regenerative process of the present embodiment will be described with reference to the flowchart ofFIG.7. This process is executed by the control units170and270at a predetermined cycle when the regenerative voltage is generated. In S201, the control units170and270determine whether or not the relay intermediate voltage Vbc is larger than a regeneration determination value Vthr. The regeneration determination value Vthr is set to an arbitrary value that is larger than the normal upper limit value of the power supply voltage and smaller than a minimum value of a withstand voltage of the circuit component. When it is determined that the relay intermediate voltage Vbc is larger than the regeneration determination value Vthr (S201: YES), the process proceeds to S202, and when it is determined that the relay intermediate voltage Vbc is equal to or less than the regeneration determination value Vthr (S201: NO), the process proceeds to S203.

In S202, the control units170and270turn on the reverse connection protection relays142and242of both systems, and regenerate the electric power to the batteries191and291of both systems. That is, even if the reverse connection protection relay is turned off in the voltage drop system, if excessive regeneration occurs, the reverse connection protection relays142and242of both systems are turned on so that overregeneration to the normal system side is prevented by regenerating power on the voltage drop system side as well.

In S203, the control units170and270continue the on/off state of the reverse connection protection relays142and242according to the voltage drop state. When one of the reverse connection protection relays is turned off due to a voltage drop, the regenerative power is regenerated to the normal system side.

In the present embodiment, the relay-to-relay connection line300is configured so that a boost voltage higher than the supply voltages Vb1and Vb2can be applied from the booster circuit160. This makes it possible to initially check the power relay units140and240.

The initial check process of the present embodiment will be described with reference to a flowchart ofFIG.8. This process is executed by the control units170and270when the start switch of the vehicle is turned on. InFIG.8, the first reverse connection protection relay142is described as “MOSr1”, and the second reverse connection protection relay242is described as “MOSr2”.

In S301, the control units170and270turn off all the elements of the power supply relay units140and240, that is, the power supply relays141and241and the reverse connection protection relays142and242. Further, the control units170and270turn on the booster switch161and apply a boost voltage Vu to the relay-to-relay connection line300. In the present embodiment, the resistor162is provided between the booster circuit160and the relay-to-relay connection line300, and the boost voltage Vu is applied to the relay-to-relay connection line300in a state where the current is limited. The current may be limited by a configuration different from that of the resistor162. Further, when a booster circuit, a booster switch and a resistor are provided for each system, the control units170and270may control the booster switch of the own system.

In S302, the control units170and270determine whether or not the relay intermediate voltage Vbc is equal to the boost voltage Vu. Here, if the relay intermediate voltage Vbc is within a normal determination range including the boost voltage Vu, it is considered that the relay intermediate voltage Vbc and the boost voltage Vu are equal. The same applies to the determinations of S305and S306. The normal determination range can be set as appropriate. When it is determined that the relay intermediate voltage Vbc is different from the boost voltage Vu (S302: NO), the process proceeds to S309and an abnormality measure is taken. When it is determined that the relay intermediate voltage Vbc is equal to the boost voltage Vu (S302: YES), the process proceeds to S303.

In S303, the control unit170turns off the booster switch161. In S304, the control unit170turns on the first reverse connection protection relay142. At this time, the second reverse connection protection relay242is left off.

In S305, the control units170and270determine whether or not the relay intermediate voltage Vbc is equal to the first supply voltage Vb1. When it is determined that the relay intermediate voltage Vbc is different from the first supply voltage Vb1(S305: NO), the process proceeds to S309and an abnormal measure is taken. When it is determined that the relay intermediate voltage Vbc is equal to the first supply voltage Vb1(S305: YES), the process proceeds to S306. In S306, the first control unit170turns off the first reverse connection protection relay142, and the second control unit270turns on the second reverse connection protection relay242.

In S307, the control units170and270determine whether or not the relay intermediate voltage Vbc is equal to the second supply voltage Vb2. When it is determined that the relay intermediate voltage Vbc is different from the second supply voltage Vb2(S307: NO), the process proceeds to S309and an abnormal measure is taken. When it is determined that the relay intermediate voltage Vbc is equal to the second supply voltage Vb2(S307: YES), the process proceeds to S308, and it is determined that the reverse connection protection relays142and242function normally.

An order of the processes of S304and S305and the processes of S306and S307may be changed. Further, the determination process of S305may be performed by the first control unit170, and the determination process of S307may be performed by the second control unit270.

The initial check for confirming that the power supply relays141and241function normally is performed by a separate process. Further, during normal driving, a current, a drain source voltage and an element overheating of the first power supply relay141are monitored, and if an abnormality is detected, the first power supply relay141is turned off and the operation in the second system L2is continued. Further, during normal driving, a current, a drain source voltage and an element overheating of the second power supply relay241are monitored, and if an abnormality is detected, the second power supply relay241is turned off and the operation in the first system L1is continued.

As described above, the ECU10is a “redundant unit” having two systems, the first system L1being connected to the first battery191and the second system L2being connected to the second battery291. As shown inFIG.9, a plurality of redundant units are connected to the batteries191and291to form a redundant power supply network. For example, the redundant unit RU1is an electric power steering device, the redundant unit RU2is an electric brake device, and so on, and each of the redundant units is a different device.

In the power supply system501shown inFIG.9, in the plurality of redundant units RU1to RUn, the first battery terminal B1is connected to the first battery191and the second battery terminal B2is connected to the second battery291in a system-specific parallel connection.

As described above, the ECU10of the present embodiment includes the first power supply relay unit140, the second power supply relay unit240, the relay-to-relay connection line300, the first supply regeneration control circuit155, the second supply regeneration control circuit255, and the control units170and270.

The first power supply relay unit140includes the first reverse connection protection relay142, which is connected so that the anode of the parasitic diode is on the high potential side and the cathode is on the low potential side, and the first power supply relay141, which is connected in series with the low potential side of the first reverse connection protection relay142so that the cathode of the parasitic diode is on the high potential side and the anode is on the low potential side, The first power supply relay unit140is connected to the first battery191.

The second power supply relay unit240includes the second reverse connection protection relay242, which is connected so that the anode of the parasitic diode is on the high potential side and the cathode is on the low potential side, and the second power supply relay241, which is connected in series with the low potential side of the second reverse connection protection relay242so that the cathode of the parasitic diode is on the high potential side and the anode is on the low potential side, The second power supply relay unit240is connected to the second battery291. The relay-to-relay connection line300connects the intermediate point M1between the first reverse connection protection relay142and the first power supply relay141and the intermediate point M2between the second reverse connection protection relay242and the second power supply relay241.

The first supply regeneration control circuit155includes the first reverse connection protection relay driver156and the voltage monitor circuits157,158. The first reverse connection protection relay driver156drives the first reverse connection protection relay142. The voltage monitor circuit157monitors the first supply voltage Vb1on the high potential side of the first reverse connection protection relay142. The voltage monitor circuit158monitors the relay intermediate voltage Vbc, which is the voltage of the relay-to-relay connection line300, on the low potential side of the first reverse connection protection relay142.

The second supply regeneration control circuit255includes the second reverse connection protection relay driver256and the voltage monitor circuits257and258. The second reverse connection protection relay driver256drives the second reverse connection protection relay242. The voltage monitor circuit257monitors the second supply voltage Vb2on the high potential side of the second reverse connection protection relay242. The voltage monitor circuit258monitors the relay intermediate voltage Vbc on the low potential side of the second reverse connection protection relay242.

The control units170and270control the on/off operation of the reverse connection protection relays142and242based on the first supply voltage Vb1, the second supply voltage Vb2and the relay intermediate voltage Vbc. In the present embodiment, since the reverse connection protection relays142and242and the power supply relays141and241are connected by the relay-to-relay connection line300, even if an abnormality occurs in one of the batteries191and291, it is possible to continue power supply to both systems from the other of the normal batteries191and291. As a result, even if one of the batteries191and291has an abnormality, the operation can be continued appropriately.

The relay-to-relay connection line300is connected to the booster circuit160capable of supplying a higher voltage than that of the batteries191and291via the booster switch161and the resistor162. When the boost voltage Vu from the booster circuit160is applied to the relay-to-relay connection line300in a state where all the relay elements of the power relay units140and240are off, and if the relay intermediate voltage Vbc and the boost voltage Vu do not match, the control units170and270determine that the abnormality is present. As described above, a difference of the degree of error is allowed, and if it is within the normal determination range, it is considered that the relay intermediate voltage Vbc and the boost voltage Vu match. This makes it possible to appropriately determine whether or not the reverse connection protection relays142and242function normally.

The control unit170turns off the first reverse connection protection relay142when it is determined that the first supply voltage Vb1is abnormal based on the first supply voltage Vb1and the relay intermediate voltage Vbc. Further, the control unit270turns off the second reverse connection protection relay242when it is determined that the second supply voltage Vb2is abnormal based on the second supply voltage Vb2and the relay intermediate voltage Vbc. As a result, it is possible to cut off the power supply system on the abnormal side while the power supply to the downstream side of the power supply relay units140and240is continued.

The first reverse connection protection relay142or the second reverse connection protection relay242that has been turned off due to an abnormality in the supply voltage is referred to as an abnormal system relay. When the regenerative power is generated and the relay intermediate voltage Vbc is larger than the regenerative determination value Vthr, the control units170and270turn on the abnormal system relay. As a result, when a relatively large regenerative power is generated, by regenerating the batteries191and291on both sides, it is possible to prevent the battery from being destroyed due to excessive regenerative power on the normal side.

The power supply system501includes redundant units RU1to RUn in which the ECU10is provided for each unit, the first battery191and the second battery291. The plurality of redundant units RU1to RUn are connected in parallel to the batteries191and291. Thereby, power can be appropriately supplied from the two batteries191and291to the plurality of redundant units RU1to RUn.

In the present embodiment, the ECU10corresponds to an “electronic control unit”, the first power supply relay141corresponds to a “first low potential side relay”, the first reverse connection protection relay142corresponds to a “first high potential side relay”, the second power supply relay241corresponds to a “second low potential side relay”, and the second reverse connection protection relay242corresponds to a “second high potential side relay”. Further, the first supply regeneration control circuit155corresponds to a “first relay control circuit”, the first reverse connection protection relay driver156corresponds to a “first relay driver”, the voltage monitor circuit157corresponds to a “first upper monitor circuit”, the voltage monitor circuit158corresponds to a “first lower monitor circuit”, the second supply regeneration control circuit255corresponds to a “second relay control circuit”, the second reverse connection protection relay driver256corresponds to a “second relay driver”, the voltage monitor circuit257corresponds to a “second upper side monitor circuit”, and the voltage monitor circuit258corresponds to a “second lower side monitor circuit”.

The booster switch161corresponds to a “switch” and the resistor162corresponds to a “current limiting circuit”. Further, the first battery191corresponds to a “first external power supply”, and the second battery291corresponds to a “second external power supply”.

Other Embodiments

In the above embodiment, the first system and the second system are connected to the common ground. In another embodiment, the ground of the first system and the ground of the second system may be separated. Further, in the above embodiment, the first system circuit C1is provided on the downstream side of the first power supply relay unit, and the second system circuit C2is provided on the downstream side of the second power supply relay unit. In another embodiment, the circuit on the downstream side of the first power supply relay unit and the second power supply relay unit may be one system. Similarly, even if the configuration on the downstream side of the power supply relay unit is one system, the operation can be continued when the power supply system is abnormal.

In the above embodiment, a resistor is used as a current limiting circuit for limiting the current from the booster circuit to the relay-to-relay connection line. In other embodiments, the current limiting circuit may be configured with elements other than resistors.

Further, in the above embodiment, two motor windings, two inverter units and two control units are provided. In another embodiment, for example, one control circuit may be provided for a plurality of motor windings and a plurality of inverter circuits. A plurality of inverter circuits and a plurality of motor windings may be provided for one control circuit. That is, the numbers of the motor windings, inverter circuits and control circuits may be different.

In the above embodiment, the motor is a three-phase brushless motor. In other embodiments, the motor may be something other than a three-phase brushless motor. Further, the rotary electric machine may be a motor-generator that also has a function of a generator. Further, the load may be something other than the motor. In the above embodiment, the electronic control unit and the power supply system are applied to the electric power steering device. In other embodiments, the electronic control unit and the power supply system may be applied to a steering device other than the electric power steering device that controls steering, such as a steer-by-wire device. Further, the electronic control unit and the power supply system may be applied to an in-vehicle device other than the steering device or a device other than the in-vehicle device. The configuration on the downstream side of the power relay unit may be a circuit configuration different from that of the motor winding and the inverter related to the motor drive.

The control circuit and method described in the present disclosure may be implemented by a special purpose computer which is configured with a memory and a processor programmed to execute one or more particular functions embodied in computer programs of the memory. Alternatively, the control circuit described in the present disclosure and the method thereof may be realized by a dedicated computer configured as a processor with one or more dedicated hardware logic circuits. Alternatively, the control circuit and method described in the present disclosure may be realized by one or more dedicated computer, which is configured as a combination of a processor and a memory, which are programmed to perform one or more functions, and a processor which is configured with one or more hardware logic circuits. The computer programs may be stored, as instructions to be executed by a computer, in a tangible non-transitory computer-readable medium. The present disclosure is not limited to the embodiment described above but various modifications may be made within the scope of the present disclosure.

The present disclosure has been described in accordance with embodiments. However, the present disclosure is not limited to this embodiment and structure. This disclosure also encompasses various modifications and variations within the scope of equivalents. Furthermore, various combination and formation, and other combination and formation including one, more than one or less than one element may be made in the present disclosure.