JP7589624B2 - Power System - Google Patents

Description

The present invention relates to a power supply system.

JP 2018-196177 A discloses a power supply system that can continue to supply power to an electric load including an inverter even if an abnormality occurs in a part of the power supply system (reference numerals in parentheses in the background art are those of the referenced document). This power supply system includes two relatively high-voltage power supplies (10, 11) and one relatively low-voltage power supply (70), and includes one DC converter (50, 60) between one high-voltage power supply (10) and the low-voltage power supply (70), and between the other high-voltage power supply (11) and the low-voltage power supply (70). The low-voltage power supply (70) is configured to be able to supply power via each DC converter (50, 60). If one DC converter (50 or 60) fails, power can be continued to be supplied to the low-voltage power supply (70) via the other DC converter (60 or 50). This allows power to be continuously supplied to the electrical load (71) that receives power from the low-voltage power source (70).

JP 2018-196177 A

The above power supply system proposes fail-safe technology that assumes failure of the DC converter or low-voltage power supply, but failures may occur in the high-voltage power supply or its supply path. In addition, the electrical loads that receive power from the low-voltage power supply (70) may include those that do not necessarily require a continuous power supply. Recently, electrification and automation have been promoted in various systems. Promoting electrification and automation requires appropriate electrical load distribution throughout the entire product system and a power supply form that is appropriate for the load distribution. For this reason, there is still room for improvement in the above power supply system.

In light of the above, it is desirable to provide technology that can appropriately construct a power supply system that supplies power to loads that operate at relatively high voltages and loads that operate at relatively low voltages.

In view of the above, a power supply system including a first storage device, a second storage device, a first inverter electrically connected to the first storage device, and a second inverter electrically connected to the second storage device includes a first step-down converter that steps down and outputs an input voltage input from the first storage device, a second step-down converter that steps down and outputs an input voltage input from the second storage device, a first load group, and a second load group, in which power is supplied from one of the first step-down converter and the second step-down converter to the first load group, and power is supplied from the other step-down converter of the first step-down converter and the second step-down converter to the second load group.

According to this configuration, power can be supplied from the storage device to the inverter, and also from the storage device to the first load group and the second load group via the step-down converter. In other words, there is no need to provide a separate power source to supply power to electrical loads that operate at a lower voltage than the inverter, and the power supply system can be simplified. In addition, because power is supplied from different storage devices via different step-down converters to the first load group and the second load group, the power stored in the storage devices can be used in a balanced manner. In other words, according to this configuration, a power supply system can be appropriately constructed that supplies power to loads that operate at a relatively high voltage and loads that operate at a low voltage.

Further features and advantages of the power supply system will become apparent from the following description of exemplary, non-limiting embodiments, which are illustrated in the drawings.

FIG. 1 is a schematic circuit block diagram showing a first configuration example of a power supply system; FIG. 2 is a schematic circuit block diagram showing a second configuration example of a power supply system; Schematic circuit block diagram showing a configuration example of a single step-down converter Schematic circuit block diagram showing a configuration example of a multi-step-down converter FIG. 11 is a schematic circuit block diagram showing a third configuration example of a power supply system; FIG. 13 is a schematic circuit block diagram showing a fourth configuration example of the power supply system.

The following describes an embodiment of the power supply system using a system in a vehicle that uses a rotating electric machine as a driving force source for the vehicle as an example. However, this does not prevent the power supply system from being used in other applications. Figures 1, 2, 5, and 6 are schematic circuit block diagrams showing the configuration of a power supply system 100. Although details will be described later, the block diagram of Figure 1 shows a first configuration example of the power supply system 100, and when distinguishing it from other configuration examples, it will be referred to as a first power supply system 100A. Similarly, the power supply system 100 in the block diagram of Figure 2 showing the second configuration example will be referred to as a second power supply system 100B. Similarly, the power supply system 100 in the block diagram of Figure 5 showing the third configuration example will be referred to as a third power supply system 100C, and the power supply system 100 in the block diagram of Figure 6 showing the fourth configuration example will be referred to as a fourth power supply system 100D. When there is no need to distinguish between them, such as when there are matters common to each of them, they will be simply referred to as the power supply system 100.

The rotating electric machine 80 is a driving force source for the wheels of a vehicle such as an electric vehicle or a hybrid vehicle. The rotating electric machine 80 is an open-winding type rotating electric machine having a stator coil 8 (open winding) of multiple phases (three phases in this embodiment) that are independent of each other. An inverter 30 that is controlled independently and converts power between direct current and multiple phases (three phases in this embodiment) of alternating current is connected to each end of the stator coil 8. That is, a first inverter 31 is connected to one end of the stator coil 8, and a second inverter 32 is connected to the other end of the stator coil 8. Hereinafter, when there is no need to distinguish between the first inverter 31 and the second inverter 32, they will be simply referred to as inverters 30.

In this embodiment, an open-winding type rotating electric machine is exemplified, but the rotating electric machine 80 is not limited to this form. For example, a dual-winding type rotating electric machine having two sets of multi-phase stator coils connected at a neutral point may be driven and controlled by two inverters independently connected to each of the stator coils.

The inverter 30 is configured with a plurality of switching elements 3. The switching elements 3 may be IGBTs (Insulated Gate Bipolar Transistors) or power MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). FIG. 1 and other figures show an example in which IGBTs are used as the switching elements 3. In this embodiment, the first inverter 31 and the second inverter 32 are inverters 30 with the same circuit configuration using the same type of switching elements 3.

The two inverters 30 each have an AC arm for one phase that is configured as a series circuit of an upper-stage switching element 3H and a lower-stage switching element 3L. Each switching element 3 is provided with a freewheel diode in parallel, with the forward direction being from the negative pole to the positive pole (from the lower side to the upper side). In the multi-phase arms, the side that includes the upper-stage switching element 3H is referred to as the upper-stage arm, and the side that includes the lower-stage switching element 3L is referred to as the lower-stage arm.

In this embodiment, the two inverters 30 are connected to independent high-voltage DC power sources (electricity storage devices E). Between the inverters 30 and the electricity storage devices E, DC link capacitors 4 (smoothing capacitors) are provided to smooth the DC voltage. Specifically, the first inverter 31 has a first DC link capacitor 41 connected to its DC side, a DC side connected to the first electricity storage device E1, and an AC side connected to one end of the multi-phase stator coil 8, to convert power between DC and multi-phase AC. The second inverter 32 has a second DC link capacitor 42 connected to its DC side, a DC side connected to the second electricity storage device E2, and an AC side connected to the other end of the multi-phase stator coil 8, to convert power between DC and multi-phase AC.

As shown in FIG. 1 etc., the first inverter 31 is connected to the first storage device E1 via the first contactor MC1, and the second inverter 32 is connected to the second storage device E2 via the second contactor MC2. The first contactor MC1 electrically connects the first inverter 31 and the first storage device E1 in a closed state (on state), and cuts off the electrical connection between the first inverter 31 and the first storage device E1 in an open state (off state). Similarly, the second contactor MC2 electrically connects the second inverter 32 and the second storage device E2 in a closed state (on state), and cuts off the electrical connection between the second inverter 32 and the second storage device E2 in an open state (off state). The first contactor MC1 and the second contactor MC2 are, for example, configured by relays.

For example, the first storage device E1 and the second storage device E2 are DC power sources with the same ratings, such as voltage and storage capacity. The first DC link capacitor 41 and the second DC link capacitor are also capacitors with the same ratings, such as capacity. As described later, in the third power supply system 100C and the fourth power supply system 100D, for example, the storage capacity of the storage device E and the capacitance of the DC link capacitor 4 may be different. The rated voltage of the storage device E is about 200 volts to 400 volts. The storage device E is composed of, for example, a secondary battery (battery) such as a nickel-metal hydride battery or a lithium-ion battery, or an electric double layer capacitor. For example, the storage device E can be charged by being connected to a commercial power source via an on-board charger and a charging connector (not shown).

The rotating electric machine 80 can also function as both an electric motor and a generator. The rotating electric machine 80 converts the electric power from the power storage device E via the inverter 30 into motive power (power running). Alternatively, the rotating electric machine 80 converts the rotational driving force transmitted from the wheels, etc. into electric power, and charges the power storage device E via the inverter 30 (regeneration). In other words, the power storage device E is charged not only via a commercial power source, but also by the rotating electric machine 80.

The inverter 30 is controlled by a rotating electric machine control device (not shown). In this embodiment, an electric vehicle equipped with an automatic driving system is illustrated, and the rotating electric machine control device is configured as a drive control device for the electric vehicle. The rotating electric machine control device can control the first inverter 31 and the second inverter 32 using control methods independent of each other (the details of the control methods will be described later). The rotating electric machine control device is constructed with a logic circuit such as a microcomputer as its core component. For example, the rotating electric machine control device performs current feedback control using a vector control method based on a target torque (torque command) of the rotating electric machine 80 provided from another control device such as a vehicle control device (not shown), and controls the rotating electric machine 80 via the inverter 30.

The actual current flowing through the stator coil 8 of each phase of the rotating electric machine 80 is detected by a current sensor (not shown), and the magnetic pole position of the rotor of the rotating electric machine 80 at each point in time is detected by a rotation sensor (not shown), such as a resolver. The rotating electric machine control device performs current feedback control using the detection results of the current sensor and the rotation sensor. The rotating electric machine control device is configured with various functional units for current feedback control, and each functional unit is realized by the cooperation of hardware such as a microcomputer and software (programs).

The rotating electric machine control device can execute, for example, pulse width modulation control in which multiple pulses with different patterns are output in one period of the electrical angle, or square wave control in which one pulse is output in one period of the electrical angle, as the switching pattern form of the switching elements 3 that constitute the first inverter 31 and the second inverter 32. As described above, the rotating electric machine control device can control each of the first inverter 31 and the second inverter 32 using a control method independent of each other.

The rotating electric machine control device can also execute shutdown control or active short circuit control as a fail-safe control in the case where an abnormality is detected in the inverter 30 or the rotating electric machine 80. Shutdown control is a control in which the switching control signal to all switching elements 3 constituting the inverter 30 is made inactive to turn the inverter 30 off. Active short circuit control is a control in which either one side of the upper-stage switching elements 3H of all arms of the multiple phases or the lower-stage switching elements 3L of all arms of the multiple phases is turned on and the other side is turned off. Note that the case where the upper-stage switching elements 3H of all arms of the multiple phases are turned on and the lower-stage switching elements 3L of all arms of the multiple phases are turned off is referred to as upper-stage active short circuit control. Also, the case where the lower-stage switching elements 3L of all arms of the multiple phases are turned on and the upper-stage switching elements 3H of all arms of the multiple phases are turned off is referred to as lower-stage active short circuit control.

In the present embodiment, when inverters 30 are connected to both ends of the stator coil 8, when one inverter 30 is short-circuited by active short circuit control, the multi-phase stator coils 8 are short-circuited in the one inverter 30. In other words, the one inverter 30 becomes the neutral point, and the stator coils 8 are Y-connected. As described above, the rotating electric machine control device can control the first inverter 31 and the second inverter 32 by independent control methods. Therefore, the rotating electric machine control device can realize a form in which an open winding type rotating electric machine 80 is controlled via two inverters 30, and a form in which a Y-connected rotating electric machine 80 is controlled via one inverter 30 (the inverter 30 not controlled by active short circuit).

A vehicle is equipped with various systems. For example, a vehicle is equipped with at least an electric steering system, an automatic braking system, a perimeter monitoring system, a navigation system, an air conditioning system, a defroster system, an electric seat system, and a seat heater system. Each system is connected to an in-vehicle network such as a Controller Area Network (CAN), allowing the exchange of information.

The electric steering system is a system that assists the driver in steering operations and steers the vehicle during autonomous driving. The automatic braking system is a system that assists the driver in braking operations, brakes the vehicle during autonomous driving, and brakes the vehicle when an obstacle is detected. The surrounding monitoring system is a system that recognizes road signs and road markings, monitors the intrusion of obstacles into the driving route, and monitors objects around the vehicle when parking. The navigation system is a system that searches for a route to a destination and provides guidance to the destination. The air conditioning system is a system that regulates the temperature and humidity inside the vehicle. The defroster system is a system that prevents the vehicle's windows from fogging up. The electric seat system is a system that adjusts the position of the vehicle's seats. The seat heater system is a system that warms the seats during cold seasons, etc.

Here, the vehicle control device, rotating electrical machine control device, automatic braking system, perimeter monitoring system, navigation system, and power seat system are load groups rated at a low voltage of, for example, about 12 volts, and are referred to here as the "low voltage load group." The electric steering system, air conditioner system, defroster system, and seat heater system are load groups rated at a medium voltage of, for example, about 42 volts, and are referred to here as the "medium voltage load group." Note that the inverter 30 (first inverter 31 and second inverter 32) connected to the power storage device E, which has a rated voltage of 200 to 400 volts, is a load group rated at 200 to 400 volts, and are referred to here as the "high voltage load group." The above is a classification of electrical loads by rated voltage.

On the other hand, for example, among the electrical loads mounted on a vehicle, there are loads that are preferably continued to operate even if some abnormality occurs in the vehicle, i.e., loads with high importance of power supply, and loads that can be stopped to save power if some abnormality occurs in the vehicle, i.e., loads with low importance of power supply. Here, such loads with high importance are referred to as the first load group EL (Emergency Load), which is a load that requires power supply even in an emergency, and loads with low importance are referred to as the second load group NEL (Non-Emergency Load), which may stop power supply in an emergency. Both the first load group EL and the second load group NEL are electrical loads with a rated voltage lower than the rated voltage of the DC side of the inverter 30 (the rated voltage of the power storage device E (the first power storage device E1 and the second power storage device E2)).

For example, in the case of the above system, the inverter 30, which belongs to the "high voltage load group," the electric steering system, the air conditioner system, which belong to the "medium voltage load group," and the vehicle control device, rotating electrical control device, automatic braking system, surroundings monitoring system, and navigation system, which belong to the "low voltage load group," belong to the first load group EL. The other loads belong to the second load group NEL. In this embodiment, the above loads are classified as shown in Table 1 below. In the following explanation, the loads to which power is additionally supplied from the power storage device E, excluding the inverter 30, are explained as being divided into the first load group EL and the second load group NEL. Therefore, the inverter 30 does not belong to either the first load group EL or the second load group NEL.

As described above, the power supply system 100 includes two DC power sources (electric storage device E). These are high-voltage DC power sources that supply power to high-voltage loads such as the inverter 30, so the power supply system 100 includes a step-down converter 10 for supplying an appropriate rated voltage to low-voltage loads and medium-voltage loads. Details will be described later, but in the configurations shown in Figures 1 and 5 (first power supply system 100A and third power supply system 100C), the step-down converter 10 includes a first step-down converter 1 and a second step-down converter 2 that step-down the high-voltage input voltage Vin of about 200 to 400 volts from the electric storage device E to a low voltage (first voltage V1) of about 12 volts. In the configuration shown in Figure 2 (second power supply system 100B), the first step-down converter 1 and the second step-down converter 2 that step-down the input voltage Vin to a low voltage (first voltage V1) of about 12 volts and a medium voltage (second voltage V2) of about 42 volts are included. The embodiment shown in FIG. 6 (fourth power supply system 100D) includes a first step-down converter 1 that steps down the input voltage Vin to a first voltage V1, and a second step-down converter 2 that steps down the input voltage Vin to the first voltage V1 and the second voltage V2.

When distinguishing between the first step-down converter 1 and the second step-down converter 2, a step-down converter 10 that steps down the input voltage Vin only to the first voltage V1 and a step-down converter 10 that steps down the input voltage Vin to the first voltage V1 and the second voltage V2, the former (step-down to the first voltage V1 only) is called a single step-down converter 11, and the latter (step-down to the first voltage V1 and the second voltage V2) is called a multi-step-down converter 12. The first voltage V1 is, for example, rated at 12 volts (approximately 11 to 13 volts) or 24 volts (22 to 26 volts), and the second voltage V2 is, for example, rated at 36 volts (32 to 40 volts), 42 volts (38 to 46 volts), or 48 volts (43 to 53 volts).

Figure 3 shows an example of a single step-down converter 11, and Figure 4 shows an example of a multi-step-down converter 12. In this embodiment, the step-down converter 10 is an isolated converter equipped with a transformer T. The single step-down converter 11 includes one set of transformers T, and the multi-step-down converter 12 includes two sets of transformers T (a first transformer T1 and a second transformer T2). In both the single step-down converter 11 and the multi-step-down converter 12, the primary coil TP is connected to the power storage device E via a switching element. By switching the switching element, the input voltage Vin is intermittently applied to the primary coil, and an AC voltage is induced in the secondary coil TS by electromagnetic induction. The secondary circuit includes a rectifier diode D and a smoothing capacitor C. The AC voltage is rectified to DC by the rectifier diode D, and the pulsation generated during rectification is smoothed by the smoothing capacitor C.

As shown in Figures 1, 2, 5, and 6, the power supply system 100 includes a first storage device E1, a second storage device E2, a first inverter 31 electrically connected to the first storage device E1, a second inverter 32 electrically connected to the second storage device E2, a first step-down converter 1 that steps down and outputs the input voltage Vin input from the first storage device E1, a second step-down converter 2 that steps down and outputs the input voltage Vin input from the second storage device E2, a first load group EL, and a second load group NEL. Then, power is supplied to the first load group EL from the step-down converter 10 of either the first step-down converter 1 or the second step-down converter 2, and power is supplied to the second load group NEL from the step-down converter 10 of the other of the first step-down converter 1 or the second step-down converter 2.

By configuring the power supply system 100 in this manner, power can be supplied from the storage device E to the inverter 30, and power can also be supplied from the storage device E to the first load group EL and the second load group NEL via the step-down converter 10. In other words, there is no need to provide a separate power supply to supply power to an electrical load that operates at a lower voltage than the inverter 30, and the power supply system can be simplified.

As shown in Figs. 1 and 5, in the first power supply system 100A and the third power supply system 100C, the first step-down converter 1 steps down the input voltage Vin input from the first power storage device E1 to output the first voltage V1, and the second step-down converter 2 steps down the input voltage Vin input from the second power storage device E2 to output the first voltage V1. The first step-down converter 1 and the second step-down converter 2 are configured as a single step-down converter 11 shown in Fig. 3.

As shown in FIG. 2, in the second power supply system 100B, the first step-down converter 1 steps down the input voltage Vin input from the first power storage device E1 to output a first voltage V1 and a second voltage V2 higher than the first voltage V1, and the second step-down converter 2 steps down the input voltage Vin input from the second power storage device E2 to output a first voltage V1 and a second voltage V2. The first step-down converter 1 and the second step-down converter 2 are configured as a multi-step-down converter 12 shown in FIG. 4.

As shown in FIG. 6, in the fourth power supply system 100D, the first step-down converter 1 steps down the input voltage Vin input from the first power storage device E1 to output a first voltage V1, and the second step-down converter 2 steps down the input voltage Vin input from the second power storage device E2 to output the first voltage V1 and a second voltage V2 higher than the first voltage V1. The first step-down converter 1 is configured as a single step-down converter 11 shown in FIG. 3, and the second step-down converter 2 is configured as a multi-step-down converter 12 shown in FIG. 4.

As shown in Figures 1 and 5 and Table 2 below, in the first power supply system 100A and the third power supply system 100C, the first voltage V1 is supplied to both the first load group EL and the second load group NEL. Both the first load group EL and the second load group NEL include medium voltage loads, but by operating these at the first voltage V1, which is lower than the original rated voltage, the power supply system 100 can be simplified. This may potentially reduce the cost of the power supply system 100. However, this does not prevent each load from being boosted to a voltage higher than the first voltage V1 using a boost regulator or the like as appropriate.

2, 6 and Table 3 below, in the second power supply system 100B and the fourth power supply system 100D, the first load group EL is supplied with the first voltage V1, and the second load group NEL is supplied with the second voltage V2. The medium voltage loads included in the second load group NEL are supplied with the second voltage V2, which is the original rated voltage, while the medium voltage loads included in the first load group EL are supplied with the first voltage V1, which is lower than the original rated voltage. By operating the medium voltage loads included in the first load group EL at the first voltage V1, which is lower than the original rated voltage, as described below, the power supply system 100 can be simplified to take into account the occurrence of an abnormality. Note that this does not prevent each of the medium voltage loads included in the first load group EL from being boosted to a voltage higher than the first voltage V1 as appropriate using a boost regulator or the like.

As shown in FIG. 1 and FIG. 2, in the first power supply system 100A and the second power supply system 100B, the first load group EL is electrically connected to the first step-down converter 1 via the first switch S1, and the second load group NEL is electrically connected to the second step-down converter 2 via the second switch S2. Furthermore, the first load group EL is also electrically connected to the second step-down converter 2 via the third switch S3, and the second load group NEL is also electrically connected to the first step-down converter 1 via the fourth switch S4.

The step-down converters 10 of the second power supply system 100B are both multi-step-down converters 12. More specifically, the first load group EL is electrically connected to the first step-down converter 1 via the first switch S1 so that the first voltage V1 can be supplied from the first step-down converter 1, and the second load group NEL is electrically connected to the second step-down converter 2 via the second switch S2 so that the second voltage V2 can be supplied from the second step-down converter 2. Furthermore, the first load group EL is electrically connected to the second step-down converter 2 via the third switch S3 so that the first voltage V1 can also be supplied from the second step-down converter 2, and the second load group NEL is electrically connected to the first step-down converter 1 via the fourth switch S4 so that the second voltage V2 can also be supplied from the first step-down converter 1.

As shown in Figs. 5 and 6, in the third power supply system 100C and the fourth power supply system 100D, the first load group EL is electrically connected to the first step-down converter 1 via the first switch S1, and the second load group NEL is electrically connected to the second step-down converter 2 via the second switch S2. Furthermore, the first load group EL is also electrically connected to the second step-down converter 2 via the third switch S3. The second load group NEL is not electrically connected to the first step-down converter 1.

Since the second step-down converter 2 of the fourth power supply system 100D is a multi-step-down converter 12, more specifically, the first load group EL is electrically connected to the first step-down converter 1 via the first switch S1 so that the first voltage V1 can be supplied from the first step-down converter 1, and the second load group NEL is electrically connected to the second step-down converter 2 via the second switch S2 so that the second voltage V2 can be supplied from the second step-down converter 2. Furthermore, the first load group EL is electrically connected to the second step-down converter 2 via the third switch S3 so that the first voltage V1 can also be supplied from the second step-down converter 2. Since the first step-down converter 1 is a single step-down converter 11, the second load group NEL is not connected so that the first step-down converter 1 can supply the second voltage V2.

That is, in common to the four forms of the power supply system 100, at least the first load group EL is electrically connected to both the first step-down converter 1 and the second step-down converter 2 so that power can be selectively supplied from both of them. The second load group NEL is electrically connected to at least one of the first step-down converter 1 and the second step-down converter 2 so that power can be supplied from that one step-down converter 10.

With the above-mentioned configuration, in common to the four forms of power supply system 100, when power cannot be supplied from one of the step-down converters 10, power can be supplied from the other step-down converter 10 to at least the first load group EL. Therefore, even if a failure occurs in the power supply system 100, power supply to at least the first load group EL can be continued. For example, even if one of the two step-down converters 10 fails, or if the power supply from the storage device E to one of the step-down converters 10 is cut off (due to failure of the storage device E, opening of the first contactor MC1 or the second contactor MC2, etc.), power supply to the first load group EL can be continued.

As described above, the first load group EL is an electrical load that has a higher priority for power supply than the second load group NEL. By classifying the electrical loads according to the priority of power supply, it is possible to appropriately design, manage, control, etc. the power supply in the power supply system 100. Also, for example, if power cannot be supplied from one of the step-down converters 10, and power is supplied from the other step-down converter 10 to at least the first load group, power can be appropriately supplied to the first load group EL, which has a higher priority for power supply.

For example, in the first power supply system 100A shown in FIG. 1, by controlling the first switch S1 to the fourth switch S4 as shown in Table 4 below, even if a failure or the like occurs in the power supply system 100, it is possible to continue supplying power to at least the first load group EL.

For example, in the second power supply system 100B shown in FIG. 2, by controlling the first switch S1 to the fourth switch S4 as shown in Table 5 below, even if a failure or the like occurs in the power supply system 100, it is possible to continue supplying power to at least the first load group EL.

As shown in Tables 4 and 5, the first power supply system 100A and the second power supply system 100B can supply power in the first and second patterns under normal conditions. In other words, the first power supply system 100A and the second power supply system 100B can switch between the step-down converter 10 that supplies power to the first load group EL and the step-down converter 10 that supplies power to the second load group NEL under normal conditions. This makes it easy to maintain a balance between the first and second storage devices E1 and E2 by preventing the remaining charge of either the first or second storage device E1 or E2 from decreasing.

That is, it is preferable that the power supply system 100 switches between the step-down converter 10 that supplies power to the first load group EL and the step-down converter 10 that supplies power to the second load group NEL according to a predefined switching condition. Here, the switching condition may be at a predetermined time interval, or when the difference in SOC based on the state of charge (SOC) of the first storage device E1 and the state of charge of the second storage device E2 becomes equal to or exceeds a predefined value. By switching in this way, the two storage devices E can be used in a balanced manner. It is preferable that information on the SOC of the storage device E is fed back to the rotating electrical machine control device to determine the switching condition.

Although not shown in Tables 4 and 5, if the balance between the first storage device E1 and the second storage device E2 is not taken into consideration, power supply to the second load group NEL is not prevented in the event of an abnormality. For example, if power supply via the first step-down converter 1 is no longer possible, the third switch S3 may be turned on to supply power from the second step-down converter 2 to the first load group EL, and the second switch S2 may also be turned on to supply power from the second step-down converter 2 to the second load group NEL. Alternatively, if power supply via the second step-down converter 2 is no longer possible, the first switch S1 may be turned on to supply power from the first step-down converter 1 to the first load group EL, and the fourth switch S4 may also be turned on to supply power from the first step-down converter 1 to the second load group NEL.

For example, in the third power supply system 100C shown in FIG. 5, by controlling the first switch S1 to the third switch S3 as shown in Table 6 below, even if a failure or the like occurs in the power supply system 100, it is possible to continue supplying power to at least the first load group EL.

For example, in the fourth power supply system 100D shown in FIG. 6, by controlling the first switch S1 to the third switch S3 as shown in Table 7 below, even if a failure or the like occurs in the power supply system 100, it is possible to continue supplying power to at least the first load group EL.

As shown in Tables 6 and 7, in the third power supply system 100C and the fourth power supply system 100D, the first step-down converter 1 can supply power to the first load group EL, and the second step-down converter 2 can supply power to the first load group EL and the second load group NEL. In the third power supply system 100C and the fourth power supply system 100D, unlike the first power supply system 100A and the second power supply system 100B, the first step-down converter 1 cannot supply power to the second load group NEL. Therefore, as described above, the step-down converter 10 that supplies power to the first load group EL and the step-down converter 10 that supplies power to the second load group NEL cannot be switched. Since the first load group EL can be supplied with power from either step-down converter 10, the power supply to at least the first load group EL can be continued even if an abnormality occurs in the power supply system 100.

In the third power supply system 100C and the fourth power supply system 100D, the step-down converter 10 that supplies power to the first load group EL during normal operation is fixed to the first step-down converter 1, and the step-down converter 10 that supplies power to the second load group NEL is fixed to the second step-down converter 2. Therefore, the storage device E that supplies power to the first load group EL during normal operation is also fixed to the first storage device E1, and the storage device E that supplies power to the second load group NEL is also fixed to the second storage device E2. As a result, the difference between the state of charge (SOC) of the first storage device E1 and the state of charge of the second storage device E2 becomes large, and it may not be possible to use the two storage devices E in a balanced manner.

Therefore, it is preferable that the rating of the first step-down converter 1 is set based on the maximum load of the first load group EL, and the rating of the second step-down converter 2 is set based on the larger of the maximum load of the first load group EL and the maximum load of the second load group NEL. By configuring the first step-down converter 1 and the second step-down converter 2 to have ratings according to the maximum load of the supply destination via each step-down converter 10, it is possible to prevent the circuit size from becoming unnecessarily large.

As shown in Tables 6 and 7, power is supplied from the second step-down converter 2 to the second load group NEL during normal operation, and power supply from the second step-down converter 2 to the second load group NEL is cut off and power is supplied to the first load group EL during abnormal operation. In general, the operating time during normal operation is much longer, so it is not preferable to set the rating of the second step-down converter 2 to enable power supply to the first load group EL during abnormal operation. Therefore, it is preferable to classify the first load group EL and the second load group NEL so that the maximum load of the second load group NEL is greater than the maximum load of the first load group EL.

The second load group NEL is a load group with relatively high power consumption, such as a load rated at a medium voltage. Therefore, it is preferable to classify the loads so that the ratio of the maximum load of the first load group EL to the maximum load of the second load group NEL is 1:2, for example. The first step-down converter 1 and the second step-down converter 2 can be appropriately configured according to the maximum load. Since it is possible to reduce the size of one of the step-down converters 10, it is possible to simplify the power supply system 100 and reduce costs. Similarly, it is possible to make the capacity of the storage device E different.

Although not shown in Tables 6 and 7, if the discharge amount from the second power storage device E2 is not taken into consideration (if there is no need to take it into consideration), this does not prevent power from being supplied to the second load group NEL in the event of an abnormality. For example, if power supply via the first step-down converter 1 is no longer possible, the third switch S3 may be turned on to supply power from the second step-down converter 2 to the first load group EL, and the second switch S2 may also be turned on to supply power from the second step-down converter 2 to the second load group NEL.

In the above, it has been explained that, in common to the four forms of the power supply system 100, when power cannot be supplied from one of the step-down converters 10, power can be supplied from the other step-down converter 10 to at least the first load group EL. In addition, when "power cannot be supplied from one of the step-down converters 10", a case where one of the two step-down converters 10 fails, or when the power supply from the power storage device E to one of the step-down converters 10 is cut off (when the power storage device E fails, the first contactor MC1 or the second contactor MC2 is opened, etc.) is exemplified. Here, a supplementary explanation is given regarding "when the power supply from the power storage device E to one of the step-down converters 10 is cut off".

During normal operation, the first contactor MC1 and the second contactor MC2 are controlled to a closed state (on state), and power is supplied from the first power storage device E1 to the first step-down converter 1, and power is supplied from the second power storage device E2 to the second step-down converter 2. Then, power is supplied to the first load group EL and the second load group NEL via the first step-down converter 1 and the second step-down converter 2.

Here, if any abnormality (such as failure or opening due to impact) occurs in the first contactor MC1 or the second contactor MC2, the electrical connection between the storage device E and the step-down converter 10 is also cut off. As a result, the power supply from the step-down converter 10 to the load is also cut off. In addition, if an abnormality occurs in the storage device E itself, the power supply from the storage device E is cut off even if the first contactor MC1 and the second contactor MC2 are in the closed state. An abnormality in the storage device E is, for example, damage to at least a part of the multiple battery cells that make up the storage device E, or a failure of the battery controller that manages the charging and discharging of the storage device E. It is preferable that the rotating electrical machine control device is fed back with information indicating the state of the first contactor MC1 and the second contactor MC2, the detection results of the first voltage V1 and the second voltage V2 output from the first step-down converter 1 and the second step-down converter 2, etc.

If an abnormality occurs in the inverter 30, as described above, the first contactor MC1 or the second contactor MC2 is controlled to the open state (off state) as a fail-safe control, and the electrical connection between the inverter 30 and the storage device E is cut off. The inverter 30 is short-circuited by the active short circuit control as described above, and the rotating electric machine 80 is driven by the inverter 30 on the side where no abnormality occurs.

When such fail-safe control is executed, there is a possibility that one of the power storage devices E will discharge a large amount in order to drive the rotating electric machine 80, so as described above, it is preferable to continue the supply of power only to at least the first load group EL.

By executing this control when any of the first storage device E1, the second storage device E2, the first inverter 31, or the second inverter 32 fails, it is possible to continue supplying power to the first load group EL and to continue driving and controlling the rotating electric machine 80 using the other inverter 30 that is not malfunctioning. This makes it possible, for example, to appropriately move the vehicle to a repair shop or a safe parking location.

In the above, an example was described in which an insulated converter equipped with a transformer T is used as the first step-down converter 1 and the second step-down converter 2. In the case of an insulated converter, the reference potential of the high-voltage circuit including the inverter 30 and the storage device E is separated from the reference potential of the low-voltage circuit and the medium-voltage circuit including the first load group EL and the second load group NEL, and each circuit can be easily configured as an independent circuit. This makes it easier to suppress interference and interaction between the circuits. However, in cases where interference and interaction can be suppressed by another method or where the effects of interference and interaction are small, the first step-down converter 1 and the second step-down converter 2 may be configured by converters of other configurations, such as chopper type, rather than being limited to the insulated type.

1: first step-down converter, 2: second step-down converter, 10: step-down converter, 30: inverter, 31: first inverter, 32: second inverter, 100: power supply system, 100A: first power supply system (power supply system), 100B: second power supply system (power supply system), 100C: third power supply system (power supply system), 100D: fourth power supply system (power supply system), E: power storage device, E1: first power storage device, E2: second power storage device, Vin: input voltage, V1: first voltage, V2: second voltage

Claims (5)

A first power storage device;
A second power storage device;
a first inverter electrically connected to the first power storage device;
A power supply system including: a second inverter electrically connected to the second storage device,
a first step-down converter that steps down and outputs an input voltage input from the first power storage device;
a second step-down converter that steps down and outputs an input voltage input from the second power storage device;
A first loading group;
a second load group;
power is supplied to the first load group from one of the first step-down converter and the second step-down converter;
a power supply system in which power is supplied to the second load group from the other of the first step-down converter and the second step-down converter. The power supply system according to claim 1, wherein when power cannot be supplied from one of the step-down converters, power is supplied to at least the first load group from the other step-down converter. The power supply system according to claim 1 or 2, wherein the first load group is an electrical load having a higher priority for power supply than the second load group. The power supply system according to any one of claims 1 to 3, wherein the step-down converter supplying power to the first load group and the step-down converter supplying power to the second load group are switched according to a predefined switching condition. the first buck converter is capable of supplying power to the first group of loads;
the second step-down converter is capable of supplying power to the first load group and the second load group;
a rating of the first buck converter is set based on a maximum load of the first load group;
4. The power supply system according to claim 1, wherein a rating of the second step-down converter is set based on a larger one of a maximum load of the first load group and a maximum load of the second load group.

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