JPH03203501A - Power supply switching control system for motor vehicle - Google Patents

Abstract

PURPOSE:To perform charging operation well during regenerative operation regardless of vehicle speed by switching the connecting condition of a secondary battery unit according to the vehicle speed at the charging operation when the secondary battery unit is charged. CONSTITUTION:A controller 1 takes in data and performs torque calculation. If regenerative operation is not required and the residual capacity of battery exceeds 70% of full capacity, generator regulation processing is carried out followed by current estimation thus judging whether the battery unit is under switching operation. When some power supply system is determined based on an estimated load current and an actual vehicle speed, the controller 1 determines a power supply system based on the load current value and the vehicle speed value. If these two power supply systems are different, the estimated load current is compared with the actual load current, and if the former is higher and the predetermined power supply system is different from current power supply system, a switching request to a power supply system obtained from an estimation map is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric vehicle equipped with at least a secondary battery as a power source for an electric motor, and particularly relates to a power source switching control method during regeneration.

[Prior Art] Electric vehicles equipped with a motor as a driving force source are conventionally known. FIG. 11 is a diagram showing an example of the configuration of a conventional electric vehicle. FIG. 11(a) is an example in which two motors are arranged in series to drive the front or rear wheels, and FIG. 11(b) is an example in which two motors are arranged in series to drive the front or rear wheels. An example in which the rear wheels are driven by two separate motors, and (C) is an example in which the four wheels are driven by four separate motors. ~70
indicates a motor, and 71 to 73 indicate differential gears. As a power supply device for driving these motors, secondary batteries (hereinafter referred to as batteries) are usually connected in series or in parallel.

[Problems to be Solved by the Invention] Incidentally, in electric vehicles, during regeneration, the back electromotive force generated by the wheel motor is used to charge the battery and perform regenerative braking. Conventionally, multiple batteries are simply connected in parallel or series in a fixed manner, resulting in problems such as not being charged, or a large charging current flowing through the batteries, causing severe deterioration of the batteries and shortening their lifespan. was occurring. In other words, if the batteries are connected in series, the power supply voltage will be high, but when regenerating at low speeds, the voltage generated in the wheel motor is low, so charging will not occur. It is. On the contrary,
If the batteries are connected in parallel, the power supply voltage is low, so charging is possible even during regeneration when driving at low speeds, but when regeneration occurs when driving at high speeds, the voltage generated in the wheel motor is high. Therefore, since the charging current becomes large, the battery deteriorates and its lifespan is shortened.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a power supply switching control system for an electric vehicle that can perform good charging regardless of vehicle speed during regeneration.

[Means for Solving the Problems] In order to achieve the above object, a power supply switching control method for an electric vehicle according to the present invention includes a plurality of secondary battery units as a power source of an electric motor, and a plurality of secondary battery units. In a power supply switching control system for an electric vehicle, the connection state of which is switched between parallel connection, series connection, or a combination of parallel connection and series connection according to the driving state, for the plurality of secondary battery units. When charging is performed, the connection state of the plurality of secondary battery units is switched according to the vehicle speed at the time of charging.

[Function and Effects of the Invention] In the present invention, the power supply device is composed of at least two battery units, and these battery units are switched according to the vehicle speed and load current under the control of the control device. When regeneration is performed, the power supply method is determined according to the vehicle speed at that time so that charging can be performed satisfactorily. Specifically, when the vehicle speed is less than a threshold value, a power supply system is used in which battery units are connected in parallel, and when the vehicle speed is above the threshold value, a power supply system is used in which battery units are connected in series.

Therefore, when the voltage generated in the motor is low, such as during regeneration when driving at low speeds, the power supply voltage is kept low, so charging can be performed well. When the voltage is high, the power supply voltage is also high, so the charging current is not so large, and the battery unit deteriorates very little.

As described above, according to the present invention, charging and regenerative braking can be performed without deteriorating the battery.

[Example code] Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of a power supply switching control method for an electric vehicle according to the present invention, in which 1 is a control device, 2 is a generator, 3 is an engine, 4 is a fuel tank, and 5 is a starter, 6 is a throttle, 7 is a clutch, 8 is a smoothing circuit, 9 is a switching circuit, 10 is a battery, 11 is a motor control circuit, 12 is a motor, 13 is an accelerator opening sensor, 14
15 indicates the brake sensor, and 15 indicates the shift lever sensor.

In FIG. 1(a), a control device 1 forms the center of the power supply switching control method for an electric vehicle according to the present invention, and includes an arithmetic device such as a microprocessor and a RAM 1R.
It is composed of an OM memory device, and determines the power supply system and the torque to be applied to the motor 12 by performing processing to be described later. Furthermore, since the control device 1 performs digital processing, it is provided with an A/D converter to digitize analog input signals from each sensor.

The generator 2 generates alternating current using an engine 3, and the generated alternating current is converted into direct current by a smoothing circuit 8 and guided to a switching circuit 9. The engine 3 uses gasoline or the like as fuel, and the fuel is stored in a fuel tank 4. Therefore, the larger the capacity of the fuel tank 4, the longer the vehicle can travel. Further, the starter 5 is for starting the engine 3, is composed of a motor, and is further equipped with a battery (not shown) for starting the starter 5. The throttle 6 adjusts the amount of air-fuel mixture supplied to the engine 3, and its opening degree is determined by the control line 2.
The rotational speed of the engine 3 and, therefore, the rotational speed of the generator 2 is determined by a control signal notified from the control device 1 via 0. The clutch 7 is for transmitting or not transmitting the rotation of the engine 3 to the generator 2, and whether or not to transmit it is determined by a control signal notified from the control device 1 via the control line 21. Ru. In addition, when the switching circuit 9 described later is configured as shown in FIG. 2, the generated voltage of the generator 2 is changed due to the presence of the diode D8. A similar function can be achieved by lowering the voltage than that of J-10, so the clutch 7 can be omitted. Here, when the battery 10 is composed of two battery units (Vl, V2) as shown in FIG. 2, the voltage of the battery 10 is the voltage when these battery units (Vl, V2) are connected in parallel, or This is the voltage when connected.

The smoothing circuit 8 converts the alternating current generated by the generator 2 into direct current and guides it to the switching circuit 9, and can be constructed by bridge-connecting diodes. Further, the voltage value between the output terminals of the smoothing circuit 8 and the current value flowing into the switching circuit 9 are inputted to the control device 1 via the signal line 22.

The switching circuit 9 switches the connection state between the smoothing circuit 8 and the battery 10 in parallel or in series in response to a control signal notified from the control device 1 via the control line 23, and switches between four types of power supply systems, which will be described later. It consists of a switching circuit using transistors and diodes. In addition, from the switching circuit 9 to the motor control circuit 1 which is the load
1 (hereinafter referred to as load current) is taken into the control device 1 via the signal line 16.

The battery 10 may have any configuration, but in the following embodiment, as shown in FIG. 1(b), the battery 10 is configured to include two battery units) Vl and V2. is composed of eight 12V batteries connected in series. Therefore, in this case, the rated voltage of each battery unit (Vl, V2) is 98V. Note that 24 in the figure indicates the flow of discharging current from the battery 10, and 25 indicates the flow of charging current. Also, battery 10
The inter-terminal voltage value and discharge current value of each battery unit are taken into the control device 1 via the signal line 26.

The motor control circuit 11 supplies a predetermined drive current to the motor 12 using the output of the switching circuit 9 as a power source, and how much current to supply to the motor 12 is determined from the control device 1 via a control line 27. Determined by the notified command value. In order to move the vehicle forward or backward, the motor 12 must be rotated forward or reverse, and for this purpose it must be determined which coil of the motor 12 should be supplied with current. For this purpose, the motor control circuit 11 receives the output of a resolver (not shown) disposed inside the motor 12 via a signal line 29, detects the magnetic pole position of the motor 12, and determines the coil to which current is to be supplied. It is made to be. The motor control circuit 11 also has a signal line 28
The vehicle speed data is notified to the control device 1 via. In addition,
The motor control circuit 11 is constituted by a switching circuit, which is a conventionally widely known circuit, and therefore the details of its configuration will be omitted.

As the motor 12, one having a conventionally known configuration can be used. Although only one motor is shown in the figure, this is a representation of all motors, and the present invention can be applied to electric vehicles that use multiple motors. Of course.

The outputs of the accelerator opening sensor 13, brake sensor 14, and shift lever sensor 15 are each connected to a signal line 3013.
1.32 to the control device 1. The accelerator opening sensor 13 detects the amount of depression of the accelerator (not shown), and the brake sensor 14 detects the amount of depression of the accelerator (not shown).
The shift lever sensor 15 determines whether the shift lever is in the forward position, reverse position, or neutral position. Well-known sensors can be used in each case.

For example, as shown in FIG. 2, the switching circuit 9 is composed of seven transistors Trl-Tr7 and eight diodes DI-DB. A diode DI-D7 connected in parallel to the transistor Tri-Tr7 is for absorbing back electromotive force generated when switching the transistor.

In addition, in FIG. 2, Vl.

V2 indicates a battery unit of the battery 10.

In this embodiment, the transistors of the switching circuit 9 are switched as shown in FIG. 3(a), and the transistors in the switching circuit 9 are switched as shown in FIG.
The four types of power supply systems shown in e) are configured. In Fig. 3(a), the rOJ mark indicates an on state, the "x" mark indicates an off state, and the "△" mark indicates an on state when charging and an off state when not charging, indicating that transistors Tri and Tr7 are on. , when the other transistors are off, as shown in FIG. 3(b), the battery unit Vl.

v2 is connected in series, and the generator 7 is connected in parallel to this. This is the first power supply system, and is a power supply system suitable for high-speed driving. In addition, in the first power supply method, it is possible to charge the battery units Vl and V2, and when charging, the transistors Trl"Tr3,
Tr7 is turned on and the other transistors are turned off. The second power supply method shown in FIG. 3(C) is the generator 7
, battery unit) Vl and battery unit) V2 are connected in parallel, making it possible to generate high torque.

Further, with this power supply method, it is possible to charge the battery units Vl and V2. During charging, transistors Tri to Tr3 are turned off and transistors Tr4 to Tr7 are turned on, and when charging is not performed, only transistor Tr7 is turned on. Also, the transistor T r2.
When the TrLTr7 is on and the other transistors are off, the battery unit connected in parallel with the generator 7 is connected in series, as shown in FIG. 3(d). This is the third power supply system, and is suitable for medium-speed and long-distance travel. The fourth power supply system uses only the generator 7, as shown in FIG. 3(e), and all transistors are turned off. The fourth power supply method is a low-power power supply method suitable for long-distance travel, and can save battery power.

The switching and switching of the power supply system described above is performed according to instructions from the control device 1. Next, referring to FIG. 4, the control device lf1
We will explain the processing performed by . FIG. 4(a) is a diagram showing the flow of the entire process performed by the control device 1, FIG. 4(b) is a diagram showing the flow of the switching process therein, and FIG. 4(C) is a diagram showing the flow of the charging process. FIG. 3(d) is a diagram showing the flow of generator adjustment processing.

When the process starts, first, the microprocessor is initialized, and the second power system is set as the power system (Sl). Next, the control device 1 takes in various data (
S2). That is, the smoothing circuit 8 outputs the DC voltage value and current value, the switching circuit 9 outputs the load current value, and the battery 10 outputs the inter-terminal voltage value and discharge current value for each of the battery units Vl and V2. The motor control circuit 11 receives the vehicle speed, and furthermore the accelerator opening sensor 13, the brake sensor 14, and the shift lever sensor 1.
Take in the output signal of 5.

When the data acquisition is completed, the control device 1 calculates torque based on the vehicle speed and the accelerator opening (83). Torque calculation can be performed by a well-known method such as a method using a ma-knob on which a torque value corresponding to vehicle speed and accelerator opening is written.

Next, it is determined whether regeneration is necessary based on the output of the brake sensor 14 (S4), and if regeneration is in progress, the electric power generated by the motor 12 is used to charge the fuel cell 10. In S5, it is determined whether the transistor of the switching circuit 9 is being switched. This is because when charging, a certain amount of current flows through the switching circuit 9, but it is dangerous to switch the transistor on/off while the current is flowing, so the switching circuit 8 It determines whether switching is in progress. This determination can be made by detecting whether a certain period of time has elapsed after the control device 1 instructs the switching circuit 9 to switch the power supply system. If it is determined in S5 that switching is in progress, the switching is continued through the switching process in 86, and if it is not in progress, the charging process in S7 is performed and the process from 325 is performed.

In the switching process, as shown in FIG. 4(b), it is first determined whether or not switching is in progress, that is, whether or not the switching flag is set (530), and if the switching flag is not set. A flag indicating that switching is currently in progress is set in step S31. In other words, it is a contradiction that even though it is determined that switching is in progress in S5, it is determined that switching is not in progress in the next judgment as to whether or not switching is in progress. Therefore, priority is given to the judgment in S5, and in S31 By setting the switching flag, it is made clear that switching is in progress. If the switching flag is set at 831, the processing from 825 onwards is performed, and then the process returns to S2, but the next time it passes through the same loop and enters 830, the switching flag is set. Then, it is determined whether the torque is 0 or not, that is, whether or not current is flowing through the switching circuit 9 (S32). Note that the switching flag is cleared from being set upon completion of the switching process. The determination in S32 is performed to determine whether or not current is flowing prior to switching the transistor, since it is dangerous to switch the transistor while a large current is flowing through the switching circuit 9. This determination is made based on the torque value obtained in S3, but it can also be determined based on the load current value taken in S2.

If the torque is not 0, the transistor cannot be switched, so the process returns, but if the torque is 0, it is determined whether the transistor is being operated or not by determining whether the transistor operation flag is set. (S33). This is to judge whether or not the transistor is currently being switched on/off to actually switch the power supply system.If the transistor operation flag is not set, the first stage is switched on in S34. If the transistor is set, it is determined that the transistor is being operated, and the process branches to S36.

This is because, as shown in Figure 2, seven transistors are used in the switching circuit 9, and in order to switch the power supply system, it is necessary to turn these transistors on and off, that is, to switch the conduction state. If seven transistors are operated simultaneously, the battery unit of the battery 10 may shrink, so in this embodiment, the seven transistors are divided into two groups, and the on/off operation is divided into two stages. In S34, the first stage transistor operation, that is, the operation of the first group of transistors is started, and then the transistor operation indicating that the transistor is in operation, that is, switching is started. A flag is set (S35).

When the transistor operation flag is set in S35 and the process returns, the next time the routine for the switching process is entered, it is confirmed in 833 that the transistor operation flag is set, so it is determined that the transistor is being operated. Next, in step 53C3, it is determined whether the time t since the transistor operation flag was set has exceeded a predetermined time t2. This is a process for determining whether the operations of all transistors have been completed, and time t2 is the time tl required for switching the transistors in the first stage and the time tl required for switching the transistors in the second stage. is the total value of

If it is determined in S33 that the time t2 has not elapsed since the transistor operation flag was set,
Since the switching of all the transistors has not been completed, it is then determined in S37 whether or not the time t since the transistor operation flag was set has elapsed for more than t1 time. This is a process to determine whether switching of the first stage transistor is completed or not, and a time equal to or longer than the time t1 required for switching the first stage transistor must have elapsed since the transistor operation flag was set. For example, it is determined that the switching of the first stage transistor has been completed, so 838
The second stage transistor operation is performed at , but if this is not the case, it is determined that the first stage transistor operation is currently being performed, so the process returns and the first stage transistor operation continues. . In other words, since the second stage transistor operation cannot be performed until the first stage transistor operation is completed, the circuit waits until the first stage transistor operation is completed.

In step 83B, if it is determined that 12 hours or more have passed since the transistor operation flag was set,
In this case, it is determined that all the transistor operations in the first and second stages have been completed and the switching process has ended, so the switching flag is reset (S39L) and the transistor operation flag is reset (S40). , return.

As described above, the switching in S6 is performed, and when the process returns to S2 and enters S5 again, the switching has been completed, so it is determined as "no", and the charging process in S7 is performed. In the charging process, as shown in FIG. 4(C), it is first determined whether or not switching is in progress (841). This is a process to confirm again to ensure safety. If it is determined that switching is in progress, the process returns and the switching process continues; however, if switching is not in progress, It is determined whether the vehicle speed acquired in S2 is equal to or higher than a predetermined threshold value of 70 (842). Vehicle speed is threshold 70
If the above is the case, then it is determined whether the current power supply method is the first power supply method (843), and the current power supply method is the first power supply method.
If the power supply method is not the power supply method, the control device 1 sets the power supply method to the first power supply method.
In order to switch to the power supply system, a switching request is sent to the switching circuit 9 (846), and the switching process shown in FIG. 4(b) is executed (S47L). However,
If it is determined in 843 that the current power supply system is the first power supply system, a generator adjustment process (844) is performed.

The generator adjustment process is performed according to the flow shown in FIG. 4(d). First, it is determined whether it is regeneration or not (551), and if it is regeneration, the control device 1 notifies the clutch 7 of a control signal via the control line 21, disconnects the generator 2, sets the engine 3 to an idling state, and returns. (852). If it is not regenerating, it is necessary to judge whether or not switching is in progress. 553) If switching is in progress, current cannot flow through the switching circuit 9, so 85
Branches to 2 and puts engine 3 into idling state, but
If switching is not in progress, the current power supply system is detected in steps 854 to S57. When the current power supply system is the first power supply system or the second power supply system, the control device 1 notifies the throttle 6 of a control signal via the control line 20, and the output current of the generator 2 changes to the rated current. The rotational speed of the engine 3 is adjusted by adjusting the throttle opening as follows, and the output current of the generator 2 is thereby adjusted (858). When the power supply method is the first power supply method and the second power supply method, the generator 2 and the battery 10 are connected in parallel, so the generator 2
The output current flows into the battery unit of the battery 10, but if the output current of the generator 2 exceeds the rated current, there is a high possibility that the generator 2 will fail, so it is adjusted so that it is below the rated current. . Furthermore, when the power supply system is the third power supply system or the fourth power supply system, if the output voltage of the generator 2 is large, a large current will flow, so the control device 1 controls the opening of the throttle 6. and adjusts the output voltage to a predetermined constant value (859).

The above is the overall flow of the generator adjustment process.
In the generator adjustment in the charging process of a) 87,
Since it is in a regenerative state, the engine 3 is kept in an idling state.

Then, when the generator adjustment process in S44 is completed, S45
The transistor is operated and charging begins. That is, in this case, transistors Tr2 and Tr3 are turned on to enable charging in the first power supply system.

Further, in S43, if it is determined that the vehicle speed is less than the threshold value 70, it is determined whether the current power supply method is the second power supply method (848), and if the current power supply method is not the second power supply method In order to switch the power system to the second power system, the control device 1 issues a switching request to the switching circuit 9 (549), and the switching process shown in FIG. 4(b) is executed (S50). The switching circuit 9 switches the transistor on and off, but when it is determined in step 848 that the current power supply system is the second power supply system,
Generator adjustment processing (844) is followed by transistor operation (845) to perform charging. Since the transistor operation in this case is to perform charging in the second power supply system, the transistor T r 4 + T r 5
and TrB is turned on.

The charging process performed in S7 is as described above, and its meaning is as follows. During regeneration, the motor 12 performs regenerative braking, and the electric power generated at this time charges the battery 10. However, since the voltage generated in the motor 12 is proportional to the vehicle speed, the voltage becomes low at low speeds. , a high voltage will be generated if the speed is high. In addition, when charging, the voltage of the battery 10 is
It must be lower than the power generation voltage of 2. Therefore, the first
When regeneration is performed while driving at low speed due to the power supply system, the electromotive force of the motor 12 is small, but the voltage remains high because the battery units (Vl and V2) of the battery 10 are connected in series. This means that charging will not be possible. Further, when regeneration is performed while driving at high speed using the second power supply method, the electromotive force of the motor 12 is high<,
Furthermore, since the battery units Vl and V2 are connected in parallel and the voltage is in a low state, charging is possible, but the charging current becomes large, causing adverse effects such as shortening the life of the battery units.

From the above, when regeneration is performed during high-speed driving, the electromotive force of the motor 12 becomes large.
It can be seen that it is desirable to switch to a power supply system that can withstand a large charging current, and when regeneration is performed during low-speed driving, to switch to a power supply system that can perform charging even with a small electromotive force of the motor 12. Therefore, in the present invention, as shown in the flowchart of FIG. 4(C), it is determined whether the vehicle speed is greater than or equal to a threshold value of 70 or less than the threshold value, and if the vehicle speed is greater than or equal to the threshold value of 70, the vehicle can withstand a large voltage. Charging is performed using the configuration of the first power supply method that allows the threshold value vO
If it is less than that, charging is performed using the configuration of the second power supply system, which allows charging even with a small voltage. Thereby, the back electromotive force of the motor 12 generated during regeneration can be effectively utilized, and deterioration of the battery 10 can be kept to a minimum. Note that the threshold value vO may be determined by taking into account the characteristics of the motor used;
h is a rough guideline.

The above is the charging process that is performed when it is determined that regeneration is being performed in step 84. If it is determined that regeneration is not being performed in step S4, the control device 1 determines whether the remaining battery level is 70% or less. (S8).

This is a judgment to charge the battery 10 when the remaining battery level is 70% or less, and although 70% is set as the threshold in this example, it is clear that any value may be used. be. Various methods are known for determining the remaining battery power, and any method may be used, but here, the map shown in FIG. 5 will be used.

Figure 5 shows a map that determines the remaining battery capacity with respect to the terminal voltage and discharge current of a battery unit in which eight 12V batteries are connected in series.For example, if the terminal voltage is 75v1,
It can be seen that when the discharge current is 200A, the remaining battery capacity is 80%. This map is the RO inside the control device 1.
Therefore, the control device 1 can determine the remaining battery capacity by referring to the map from the inter-terminal voltage and discharge current of the battery unit y taken in S2. Note that when multiple battery units are used as shown in Figure 1 (b), the remaining battery capacity of each battery unit is determined, and the arithmetic average value of those remaining battery capacities is used to determine the remaining capacity of the battery 10. Make it the amount. Therefore, the control device 1 calculates the remaining battery levels of the two battery units, calculates the arithmetic average value of these remaining battery levels, and compares the arithmetic average value with the threshold value of 70%. Process.

If the remaining battery capacity is 70% or less, the torque τ
It is determined whether or not is less than a predetermined set value α (89), and if it is less than the set value α, the charging process shown in FIG. 4(C) is performed (S10). Note that the determination in step S9 may be made as to whether or not the accelerator opening degree θ is less than or equal to a predetermined set value β. This is because, as described above, torque is determined from the accelerator opening.

The charging process in S10 may be performed according to the flowchart shown in FIG. 4(C), but whereas the charging process in S7 is performed using the electric power generated by the motor 12, Since the charging performed is performed using the electric power generated by the generator 2, the charging process in S10 may be performed only for a predetermined specific power supply system, for example, the second power supply system. In that case, in the charging process of FIG. 4(C), step S4
2.843, S46 and S47 are not performed, and S
If the judgment during switching of 41 is determined to be "no",
Next, the processing from 848 onward may be performed.

If the remaining battery level is over 70% on S8,
Alternatively, if the load current is not 0 even if the battery remaining capacity is 70% or less, or if the charging process of 810 is completed, the generator adjustment process of FIG. 4(d) is executed (S
11), then current prediction is performed (S12).

The current prediction process is preprocessing for determining which power source system is the most suitable, and determines how much current should be applied to the motor control circuit 11 in order to generate the torque determined in S3. This is a process of calculating whether or not it is necessary to supply. This process can be performed as follows. That is, the routine shown in FIG. 4(a) is started at predetermined intervals, for example, every 5 seconds, and the torque value determined in the previous routine, the vehicle speed at that time, and the load current are The current value to be supplied to the motor control circuit 11 is predicted by proportional calculation from these values and the torque value obtained in step 83 of the current routine.

For example, as shown in Figure 6, if the torque in the previous routine was τ11, the vehicle speed was vl, and the load current was II, and the torque found in S3 this time was τ2, the vehicle speed would not change at 5m5ec. Therefore, if the vehicle speed vl is constant, the load current I2 at the torque τ2 can be determined. Another method is to store the previous and previous torque and load current, approximate the relationship between torque and load current with a straight line from those values, and use this straight line to predict the load current from the current torque. It is okay to do so. Note that when the routine in FIG. 4(a) is first started, the load current is O, and therefore, if this state continues, the load current is predicted to be 0 forever, so when the routine is first started, the load current is 0. When this happens, a predetermined load current value is temporarily set.

Once the load current is predicted as described above, it is then determined whether or not switching is in progress (S13). If switching is in progress, switching is continued in S14; if not, the predicted load current value is The power system map is referenced by
A power supply scheme suitable for supplying the predicted load current is determined.

The power supply system map is stored in the ROM in the control device 1, and as shown in Fig. 7(a) to (g), the power supply system map is mapped according to the remaining battery level, vehicle speed, and load current value. The power supply method is determined, and ■, ■, ■, and ■ in the figure indicate the first power supply method, the second power supply method, the third power supply method, and the third power supply method, respectively.
A fourth power supply method is shown. For example, when the remaining battery capacity is 70 to 80%, the second power supply method is adopted if the vehicle speed is 50 km/h1 and the load current is 100 A, and the vehicle speed is increased by the power supply shown in Figure 7(f). 1100k/h
If one load current is 3OA, the third power supply method is adopted. Note that the solid line and broken line in the map indicate that the power supply method is determined with hysteresis, and the solid line indicates that when the load current is increasing,
and the dashed line is adopted when the vehicle speed is increasing, and the broken line is adopted when the load current is decreasing and the vehicle speed is decreasing. For example, in Figure 7 (
In the map shown in f), the change from the fourth power supply system to the second power supply system is in the direction of increasing the load current, so
This is done when the load current exceeds 5OA, and since the change from the second power supply system to the fourth power supply system is in the direction of decreasing the load current, it is performed when the load current falls below 4OA. The same applies to changing from the second power supply system to the first power supply system, and if the load current increases,
The change from the first power supply method to the second power supply method is performed when the load current exceeds
This is done when the voltage falls below 12OA. In addition, since the change from the fourth power supply method to the third power supply method is in the direction of increasing vehicle speed, it is performed when the vehicle speed exceeds 80 km/h.
Since the change from the third power supply system to the fourth power supply system is in the direction of decreasing vehicle speed, it is performed when the vehicle speed falls below 70 km/h. The same applies to other maps. Note that which map in FIGS. 7(a) to (g) is used is determined by the remaining battery level, and the value determined in S8 is used as the remaining battery level.

Now, when a certain power supply system is determined in S15 based on the predicted load current and the actual vehicle speed taken in S2, the control device 1 then selects the actually measured load current value, that is, the load current value taken in S2. The power source method is determined by referring to the power source method map based on the vehicle speed (81 B). Comparing these two power supply systems, 517), if they are the same, 81
In B, it is determined whether the determined power supply method is the same as the current power supply method, and if it is the same, there is no need to change the power supply method, so the process branches to S25, but if it is different from the current power supply method. In this case, a switching request is issued to change to the power supply method determined in S16 (S19),
The switching process shown in FIG. 4(b) is performed (820).

If the power supply system determined in S15 and the power supply system determined in S16 are different, compare the magnitude of the predicted load current and the measured load current (521), and if the predicted load current is larger, compare the magnitude of the predicted load current and the power supply system determined in S15. It is determined whether the current power supply system is the same as the current power supply system (S22), and if they are the same, the process continues to 82.
5, and if they are different, the prediction map, i.e. 815
Issue a request to switch to the power supply method requested in 823),
The switching process shown in FIG. 4(b) is performed (824). Also, 82
1, if it is determined that the measured load current value is larger, 81
8, the process described above is performed, and the power supply system determined in 816 is used.

The above processing from 817 to 324 is, in short, a process for trying to adopt a power supply system that is compatible with the larger current value of the predicted load current and the measured load current, and thereby adopts a power supply system that can withstand a large current. Therefore, even if a large current flows, no failure will occur.

Once the desired power supply system is configured as described above, the control device l then adjusts the torque, load current, and vehicle speed to RA.
Store it in M (825). These data are used in the next routine when performing the torque calculation process in S3, the current prediction process in S12, etc. Note that the torque value stored here is the value found in S3, the vehicle speed is the value taken in in S2, and the load current is the actually measured load current.

Next, the control device 1 determines whether switching is in progress (3
28) If switching is in progress, the load current needs to be set to O, so instruct the motor control circuit 11 to set torque = O. 527) If switching is not in progress, the torque value obtained in S3 is used to control the motor. Instruct circuit 11 (828)
. As a result, the conduction state of the switching elements constituting the motor control circuit 11 is switched, and the instructed current is supplied to the motor 12.

When the processing in S27 or 828 is completed, the control device 1 repeats the processing from 82 onwards again, but as described above, the above processing is repeated at predetermined intervals, for example, every 5 m5ec.

As is clear from the above description, according to the present invention, in an electric vehicle equipped with a hybrid power supply device having a generator and a battery, the connection state of the generator and battery can be switched as appropriate, such that they can be connected in parallel or in series. Therefore, it is possible to adopt the most suitable power supply system for the current driving conditions, and the generator and battery can compensate for each other's shortcomings and make effective use of each.

Therefore, it is possible to satisfy various driving conditions such as long-distance driving, short-distance driving, high-speed driving, low-speed driving, high-torque driving, and low-power driving.

Furthermore, during regeneration, the power source system is switched to one that allows good charging depending on the vehicle speed at that time, so regenerative braking can be performed effectively.

In the above embodiment, the battery 10 and the generator 2 were used as the power source for the motor 12, but the present invention
It goes without saying that the present invention can also be applied to devices that use only batteries as a power source. This is because when using a battery, during regeneration, it is necessary to charge the batch IJ-10 with the electromotive force of the motor 12 and perform effective regenerative braking.

Examples are shown in FIGS. 8, 9 and 10.

However, these figures only consider regeneration;
It is clear that, for example, the procedure shown in FIG. 2 should be used to generate a discharge.

FIG. 8(a) shows two batches as the power source for the motor 12!
J-B 11. B12 is a diagram showing a configuration in which batteries B11 and B12 are transistors Tr11. If both T r 12 are off, the same figure (
connected in series as shown in b), the transistor Tyl
When both Tr1 and Tr12 are on, they are connected in parallel as shown in FIG. In this way, there are two power supply systems in the configuration shown in Figure 8(a), but by using a map similar to that shown in Figure 7, the power supply system can be switched and controlled according to the vehicle speed and load current. is clear;
In addition, if the vehicle speed is above the threshold during regeneration, the power supply method shown in FIG. 8(b) is used, and if it is less than the threshold, the power supply method shown in FIG. 8(C) is used, so that good charging can be performed. It is also clear that regenerative braking can be performed satisfactorily. It is clear to those skilled in the art that when only a battery is used as a power source in this way, the process shown in FIG. 4(a) can be applied except for the generator adjustment process.

FIG. 9(a) shows three batteries B21. as a power source for the motor 12. B22. It is a figure showing the composition when battery B23 is used, and is battery B21. B22. B23 is a transistor T r 21. Both T r 22 are off, Tr
23. When both transistors Tr'24 are on, they are connected in series as shown in FIG.
When both Tr 22 are on and Tr231 and Tr24 are both off, they are connected in parallel as shown in FIG. 2(C). In this case, as well as the one shown in Fig. 8, by using a map similar to that shown in Fig. 7, the power supply system can be switched and controlled according to the vehicle speed and load current. If it is above the threshold value, the power supply method shown in Figure 9(b) is used, and if it is less than the threshold value, the power supply method shown in Figure 9(C) is used to achieve good charging, thereby ensuring good regenerative braking. This is something that can be done.

FIG. 10(a) shows four batteries B31. B32. B33. It is a figure showing the composition when battery B34 is used, and is battery B31. B32. B3
3. When transistors Tr31 to Tr3G are all off, they are connected in series as shown in FIG.
r32. When T r 35 is on and the other transistors are off, as shown in the same figure (C), the configuration is such that two batteries are connected in series and then connected in parallel, which is suitable for medium speed driving. When all the transistors are on, they are all connected in parallel as shown in FIG. 3(d), providing a power supply system suitable for low-speed driving. Also in this case, Figures 8 and 9
By using a map similar to that shown in Figure 7, the power source system can be switched and controlled according to the vehicle speed and load current, and the vehicle speed can be changed to three stages for charging during regeneration. If the speed is high, the power supply system shown in Figure 10(b) is used, if the speed is medium, the power supply system is shown in Figure 10(C), and if the speed is low, the power supply system is shown in Figure 10(d). By doing so, it is possible to perform good charging, and thereby it is possible to perform regenerative braking well.

As is clear from the above description, according to the embodiment of the present invention, at least two batteries are used, and the connection status of these batteries can be changed depending on the vehicle speed and load current, such as series connection or parallel connection. , or by connecting those connected in series in parallel, it is possible to configure the optimal power supply system for the driving conditions at the time, and when charging during regeneration, the power supply system can be changed depending on the vehicle speed. Since switching is controlled, it is possible to perform good charging regardless of vehicle speed, and battery deterioration due to large currents at high speeds can be kept to a minimum.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications are possible. For example, the power source of the generator may not be a gasoline engine, and a fuel cell or the like may be used instead of the battery IO.

Further, in the above embodiment, the battery 10 has two battery units, but it is clear that other configurations may be used. Furthermore, the configuration of the switching circuit 9 is merely an example, and other configurations may be used, and the power supply system is not limited to the four types described above, and other configurations may also be adopted. Further, the method of calculating torque, the method of determining remaining battery power, etc. are not limited to the above embodiments, and conventionally known methods may be used.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of the power supply switching control method for an electric vehicle according to the present invention, FIG. 2 is a diagram showing an example of the configuration of a switching circuit, and FIG. 3 is a diagram for explaining the power supply system. Figure 4 is a diagram showing the flow of processing performed by the control device, Figure 5 is a diagram showing an example of a map for determining the remaining battery level, and Figure 6
Figure 7 is a diagram for explaining current prediction processing, Figure 7 is a diagram showing an example of a map for determining the power supply method, Figure 8 is a diagram showing an example of a case where the power supply device is configured with two batteries,
Figure 9 is a diagram showing an example where the power supply device is configured with three batteries, Figure 10 is a diagram showing an example where the power supply unit is configured with four batteries, and Figure 11 is a diagram of a conventional electric vehicle. It is a figure showing an example of the power supply device. DESCRIPTION OF SYMBOLS 1... Control device, 2... Generator, 3... Engine, 4... Fuel tank, 5... Starter, 6... Throttle, 7... Clutch, 8... Smoothing circuit, 9.
...Switching circuit, 10...Battery 11...Motor control circuit, 12...Motor, 13...Accelerator opening sensor, 14...Brake sensor, 15...Shift lever sensor.

Claims (1)

[Claims] (1) A plurality of secondary battery units are provided as a power source for the electric motor, and the connection state of the plurality of secondary battery units is switched between parallel connection, series connection, or a combination of parallel connection and series connection depending on the running condition. In the power supply switching control method for an electric vehicle configured as described above, when charging the plurality of secondary battery units, the connection state of the plurality of secondary battery units is switched according to the vehicle speed at the time of charging. A power supply switching control method for electric vehicles featuring: