JPH07177751A - Power supply unit for motor - Google Patents

Abstract

PURPOSE:To efficiently use a battery by preventing excessive quickening of time required until its output reaches the end voltage during discharge of the battery. CONSTITUTION:An inverter unit 4 controlled by a control circuit 8 drives an AC motor 5 by the output of a battery 1. An arithmetic circuit 10 estimates the residual capacity of the battery 1 based on a detecting signal Ic indicating a discharge current detected by a current sensor 9 and an output voltage Vc of the battery 1. A signal generating circuit 11 sets an allowable upper limit value Imax of the output current of the inverter unit 4 in such a manner that the Imax decreases at a predetermined rate as the level of signal Rc indicating a residual capacity calculated by the arithmetic circuit 10 becomes lower and said circuit 11 also gives an upper limit value command signal SImax indicating the allowable upper limit value Imax to the control circuit 8. The control circuit 8 controls in such a manner that the output current of the inverter unit 4 does not exceed said allowable limit value Imax of the inverter unit 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for an electric motor, which drives an AC electric motor at a variable speed by an inverter device using a storage battery as a power supply.

[0002]

2. Description of the Related Art When a power supply device for an electric motor of this type is applied to, for example, an electric vehicle, it is required to extend the travelable distance per charge of a storage battery as much as possible. It is necessary to use the storage battery efficiently. As one example for realizing such efficient use of the storage battery, when the electric vehicle is decelerating or traveling downhill, the electric motor is made to function as a generator to obtain an electric braking force, and at the same time, the regeneration is performed. The use of energy to charge storage batteries has been considered.

Specifically, for example, JP-A-4-18320
In the publication No. 3, an induction motor capable of operating as a generator is mounted as an auxiliary power source, the motor is used for electric braking, and the storage battery is charged by the regenerative current during the braking. An electric vehicle (a so-called hybrid car) is described. In this, in order to grasp the state of charge of a storage battery and to effectively utilize its output,
Provided with a charge capacity indicator that displays the state of charge of the storage battery, while keeping the storage battery in a normal state based on the displayed contents,
It is configured so that both electric braking and auxiliary acceleration can be properly performed.

[0004]

In the above-mentioned conventional structure, the regenerative energy is used for charging the storage battery, in other words, the storage battery is efficiently used by a method that does not waste the excess energy. However, in the conventional configuration, no consideration has been given to the causal relationship between the magnitude of the load and the amount of electricity that can be taken out from the storage battery, which has been the cause of not being able to utilize the storage battery efficiently.

That is, in the storage battery, the voltage decreases as the current is taken out, but the amount of decrease does not become proportional to the size of the load, but becomes extremely large when the load is heavy. Therefore, if an attempt is made to increase the amount of electricity to be extracted, the final voltage will be reached during heavy load while only a part of the storage capacity of the storage battery is used. Therefore, in order to use the storage battery efficiently, it is desirable to operate the storage battery with a light load as much as possible in consideration of the remaining capacity and the output current of the storage battery.

However, in the conventional configuration, since no consideration is given to such a situation, there is a case where an undesired use mode of extracting a large current from the storage battery is continued under heavy load, and in this case, the storage battery is used. There is a problem in that the time required for the output of to reach the final voltage is unnecessarily shortened, and efficient use of the storage battery cannot be realized sufficiently.

The present invention has been made in view of the above circumstances, and an object thereof is to prevent the time until the output of the storage battery reaches the final voltage when the storage battery is discharged, from being unnecessarily shortened. The purpose of the present invention is to provide a power supply device for an electric motor, which enables efficient use of a storage battery.

[0008]

In order to achieve the above-mentioned object, the present invention comprises an inverter device using a storage battery as a power source, and a power source for an electric motor adapted to drive an AC motor at a variable speed by the output of the inverter device. In the device,
While providing a remaining capacity detection means for detecting the remaining capacity of the storage battery based on the output voltage and current of the storage battery,
The upper limit value of the output current of the inverter device is configured to be provided with current limiting means for limiting the upper limit value of the output current to be smaller according to the decrease in the remaining capacity detected by the remaining capacity detecting means (claim 1).

In this case, after providing a temperature sensor for detecting the temperature of the storage battery or its vicinity, the current limiting means corrects the upper limit value of the output current of the inverter device according to the temperature detected by the temperature sensor. The configuration is good (claim 2).

The current limiting means is constructed so that the upper limit value of the output current of the inverter device can be changed and set within a predetermined allowable range, and the upper limit value of the output current of the inverter device limited by the current limiting means is set. And a display device displaying the allowable range thereof, and an adjusting device capable of arbitrarily adjusting the upper limit value of the output current of the inverter device limited by the current limiting means within the allowable range displayed on the display device. It can also be set (Claim 3).

Further, when an acceleration command signal for the AC motor is received, delay means for delaying the rising of the acceleration command signal to extend the acceleration time of the AC motor through the inverter device is provided. It is also possible (claim 4).

Further, the remaining capacity detecting means may be configured to detect the remaining capacity of the storage battery based on the fluctuation state of the output voltage and the current at the beginning of the discharge of the storage battery (claim 5).

[0013]

According to the electric power source device for the electric motor of the present invention, when the AC electric motor is driven at a variable speed by the inverter device, the capacity of the storage battery is reduced in accordance with the drive, and the remaining capacity detecting means is the storage battery. The remaining capacity is detected based on the output voltage and current of the. Further, the current limiting means limits the upper limit value of the output current of the inverter device, that is, the upper limit value of the discharge current by the storage battery, so as to decrease as the remaining capacity detected by the remaining capacity detecting means decreases. To do. Therefore, it is possible to prevent a situation in which the output of the storage battery reaches the final voltage while only a part of the storage capacity of the storage battery is used, because a large current will not be unnecessarily drawn from the storage battery under heavy load. As a result, it is possible to efficiently use the storage battery.

In the electric motor power supply device according to the second aspect, the upper limit value of the output current of the inverter device, which is limited by the current limiting means as described above, is corrected by the temperature of the storage battery or the vicinity thereof. Therefore, it becomes possible to compensate for the performance deterioration of the storage battery due to the temperature decrease.

According to another aspect of the present invention, the upper limit value of the output current of the inverter device limited by the current limiting means and the allowable range in which the upper limit value can be changed are displayed on the display device. Since the upper limit value of the output current of the inverter device can be arbitrarily adjusted within the allowable range displayed on the display device, the output current of the inverter device can be increased as necessary, which is convenient in actual use. Becomes

In the electric motor power supply device according to the fourth aspect, since the rising of the acceleration command signal to the AC electric motor is delayed, the acceleration time of the vehicle becomes longer, but the rising of the discharge current of the storage battery becomes gentle. Become,
The storage battery can be used more effectively.

According to another aspect of the present invention, the remaining capacity detecting means detects the remaining capacity of the storage battery based on the fluctuation state of the output voltage and current of the storage battery at the beginning of the discharge of the storage battery. However, since the fluctuation of the output voltage of the storage battery becomes larger as the remaining capacity decreases, it becomes possible to accurately detect the remaining capacity of the storage battery before the AC motor is driven, and the discharge current of the storage battery becomes higher. The limit function can be surely demonstrated.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is applied to an electric vehicle will be described below with reference to FIGS. Figure 1
Shows the entire electrical configuration. In FIG. 1, a three-phase output inverter device 4 is connected to both ends of an in-vehicle storage battery 1 via power supply buses 2 and 3, and an inverter electric motor 5 for driving a vehicle (for example, an induction motor) is connected by the inverter device 4. It is configured so that it can be driven at a variable speed. The current sensors 6 and 7 are provided so as to detect a load current flowing in two phases of the three-phase power supply line of the AC motor 5, and give detection signals Ia and Ib indicating the load current to the control circuit 8. It is like this.

The current sensor 9 is provided so as to detect the current flowing through the power source bus 3, that is, the discharge current of the storage battery 1, and the detection signal Ic indicating the discharge current is supplied to the arithmetic circuit 10 (referred to in the present invention as the present invention). It corresponds to the remaining capacity detecting means). The arithmetic circuit 10 is also adapted to receive the output voltage Vc of the storage battery 1, and the detection signal Ic input when the output voltage Vc of the storage battery 1 and the load current flowing through the AC electric motor 5 are input in this manner. The remaining capacity of the storage battery 1 is calculated based on the above, and the signal Rc indicating the thus calculated remaining capacity is given to the signal generating circuit 11 (corresponding to the current limiting means in the present invention).

The signal generating circuit 11 is for giving the control circuit 8 an upper limit value command signal SImax indicating the allowable upper limit value Imax of the output current of the inverter device 4, and the allowable upper limit value indicated by the upper limit value command signal SImax. The value Imax is set to decrease at a predetermined rate as the level of the signal Rc indicating the remaining capacity of the storage battery 1 decreases.

In this case, the signal generating circuit 11 responds to the decrease of the level of the signal Rc indicating the remaining capacity of the storage battery 1 as shown in FIG.
The allowable upper limit value Imax shown by is set to be reduced in a linear ratio, and the ratio is set to an appropriate value according to the characteristics of the storage battery 1.

The control circuit 8 detects the load currents Ia, Ib and the upper limit value command signal SIMa as described above.
In addition to x, an external command value signal through the signal input circuit 12,
For example, the accelerator signal Sa indicating the operation amount of the accelerator is received, and the operation mode of the inverter device 4 is controlled so that the rotation speed of the AC electric motor 5 and thus the traveling speed of the vehicle become a speed corresponding to the accelerator signal Sa. It is supposed to do. Further, the control circuit 8 controls the current sensor 6 and the current sensor 6 during the variable speed control of the AC motor 5.
Appropriate operation control (for example, control of the slip amount of the electric motor 5, overcurrent protection control, etc.) is performed based on the detection signals Ia and Ib fed back through 7.

Further, the control circuit 8 controls the inverter device 4 when controlling the inverter device 4 as described above.
Is the upper limit value of the output current of the storage battery 1, that is, the upper limit value of the discharge current of the storage battery 1, the upper limit value command signal SI from the signal generating circuit 11.
Control is performed so as not to exceed the allowable upper limit value Imax indicated by max.

As a result of the above construction, when the state of charge of the storage battery 1 is 100% (full charge state), the value indicated by the upper limit command signal SImax output from the signal generating circuit 11, that is, the inverter device. The allowable upper limit value Imax of the output current of No. 4 is the maximum value Imax as shown in FIG.
However, when the state of charge of the storage battery 1 has decreased (the state of discharge to some extent), the allowable upper limit value Imax indicated by the upper limit value command signal SImax depends on the remaining amount of charge as shown in FIG. 3 (b). Limit value I decreased at
x.

Therefore, when the accelerator signal Sa (see FIG. 2 (a)) is given in the above fully charged state, the control circuit 8 outputs the inverter device as shown in FIG. 2 (b). 4, the increase of the output current of the storage battery 1, that is, the discharge current of the storage battery 1 is allowed within the range of the maximum value Io or less, but when the accelerator signal Sa (see FIG. 3A) is given in a state of being discharged to some extent, As shown in FIG. 3B, the storage battery 1
The discharge current is suppressed to be equal to or less than the limit value Ix.

In this way, control is performed so that the upper limit value of the discharge current of the storage battery 1 becomes smaller as the remaining capacity of the storage battery 1 decreases. As a result, when the storage battery 1 is fully charged, In other words, when there is no problem even if a large current is taken out from the storage battery 1, a sufficient starting current is given to the electric motor 5 when the AC electric motor 5 is started, that is, when the vehicle is started, and the AC electric motor 5 is accelerated. That is, the vehicle is accelerated relatively quickly as shown in FIG.

On the other hand, when the storage battery 1 is discharged to some extent, the starting current of the AC motor 5 is suppressed below the limit value Ix, so that the acceleration of the vehicle is shown in FIG. 3 (c). Although it becomes slower, it does not unnecessarily draw a large current from the storage battery 1 at the time of heavy load such as when the vehicle starts, so that the storage battery 1 can be used while only a part of its storage capacity is used. The situation in which the output reaches the final voltage can be prevented in advance, and thus the storage battery 1 can be efficiently used.

A second embodiment of the present invention is shown in FIGS. 5 and 6, and only parts different from the first embodiment will be described below. That is, this embodiment is based on the signal generation circuit 1
1 is characterized in that the temperature characteristic of the storage battery 1 is taken into consideration when determining the magnitude of the upper limit value command signal SImax. As shown in FIG. A temperature sensor 11a for detecting is provided, and a temperature signal St indicating the detected temperature is applied to the signal generating circuit 11. In this case, as shown in FIG. 6A, the signal generation circuit 11 outputs the output current of the inverter device 4 indicated by the upper limit value command signal SImax under the same level of the signal Rc indicating the remaining capacity of the storage battery 1. The allowable upper limit value Imax is corrected to a higher value IH as shown in FIG. 6B when the detected temperature indicated by the temperature signal St is high, and when the detected temperature is low, as shown in FIG.
As shown in (c), the value is corrected to a lower value IL (IL <IH).

According to this embodiment having such a structure,
It becomes possible to compensate for the performance deterioration of the storage battery 1 due to the temperature decrease, and therefore it is possible to achieve efficient utilization of the storage battery 1 regardless of the temperature.

In the second embodiment, the upper limit value command signal SImax is directly corrected. However, as shown in FIG. 7A, the storage battery 1 remaining from the arithmetic circuit 10 remains. A signal Rc 'is calculated by correcting the signal Rc indicating the capacitance by the detection temperature T, specifically, the correction in which the level of the signal Rc becomes smaller as the detection temperature T is lower, and this signal Rc' is used. When the detected temperature T is high, the allowable upper limit value Imax of the output current of the inverter device 4 indicated by the upper limit value command signal SImax is calculated as shown in FIG.
As shown in FIG. 7B, the value may be corrected to a higher value IH, and when the detected temperature T is low, the value may be corrected to a lower value IL as shown in FIG. 7C.

Further, in the first embodiment, in the signal generating circuit 11, the allowable upper limit value Imax indicated by the upper limit value command signal SImax is set in advance in response to the decrease in the level of the signal Rc indicating the remaining capacity of the storage battery 1. Although the configuration is made smaller at the ratio (see FIG. 4), it may be configured as shown in FIGS. 8 and 9 showing the third embodiment of the present invention.

That is, in FIG. 8, the signal generation circuit 11
Is the level of the signal Rc indicating the remaining capacity of the storage battery 1 and the allowable upper limit value Imax indicated by the upper limit value command signal SImax.
It is configured such that the ratio can be changed and set within a predetermined allowable range ΔImax shown in FIG. 9, and the changing operation can be performed by the adjusting device 13 which can be operated by the driver. The display device 14 is configured to display the permissible upper limit value Imax actually set in the signal generating circuit 11 and the permissible range ΔImax as described above so that the driver of the vehicle can visually check the permissible upper limit value Imax.

With this configuration, even when the storage battery 1 is in a discharged state to some extent, if the output increase of the AC motor 5 is unavoidable, such as a sudden acceleration of a car, a signal is generated. By adjusting the ratio between the level of the signal Rc set by the generating circuit 11 and the allowable upper limit value Imax within the allowable range ΔImax displayed on the display device 14, a relatively large current can be taken out from the storage battery 1. As a result, it becomes possible to appropriately deal with the above situation.

Further, as shown in FIG. 10 showing the fourth embodiment of the present invention, the ratio between the level of the signal Rc set by the signal generating circuit 11 and the allowable upper limit value Imax indicated by the upper limit value command signal SImax is calculated as follows. The pattern may be changed stepwise according to the level of the signal Rc.
Also in this case, the change ratio of each stage can be changed by an external operation within a predetermined allowable range.

In addition, FIG. 11 showing a fifth embodiment of the present invention.
As described above, the control circuit 8 is provided with a delay function of delaying the rising of the accelerator signal Sa to obtain the auxiliary accelerator signal Sa ′, and the inverter device 4 of the inverter device 4 has a speed corresponding to the auxiliary accelerator signal Sa ′. It is also possible to adopt a configuration for controlling the acceleration mode. When such a configuration is adopted, although the acceleration time of the vehicle becomes longer, the discharge current of the storage battery 1 rises more slowly. It can be used effectively. In this embodiment, the control circuit 8 functions as the delay means in the invention described in claim 4. In addition, it is desirable that the delay control of the accelerator signal Sa as described above is actually performed only when the signal Rc indicating the remaining capacity of the storage battery 1 falls below a predetermined level.

Further, in each of the above-mentioned embodiments, the storage battery 1 is used as the remaining capacity detecting means in accordance with the driving of the AC motor 5.
Although the arithmetic circuit 10 for calculating the remaining capacity of the storage battery 1 when the discharge current of 6 is provided, the remaining capacity is calculated as in the sixth embodiment of the present invention shown in FIG. You can also do it.

That is, in the sixth embodiment, the AC motor 5
Prior to driving the control circuit 8 through the inverter device 4 through a voltage of a preset pattern (for example, as shown in FIG.
A pulse signal Sp shown in (a) is output, and the detection signal Ic indicating the output voltage Vc and the discharge current of the storage battery 1 at that time is read by the arithmetic circuit 10. In the arithmetic circuit 10, the read detection signal Ic is the same. The remaining capacity of the storage battery 1 is calculated based on the magnitude of the change in the read voltage Vc at the timing. That is, since the fluctuation of the output voltage Vc of the storage battery 1 has a property of becoming larger as the remaining capacity decreases, as shown in FIG. 12C, when the fluctuation amount of the output voltage Vc is relatively small, the remaining voltage remains. It can be seen that the capacity is large, and conversely, when the fluctuation amount of the output voltage Vc is relatively large as shown in FIG. 12D, the remaining capacity is small. Therefore, the remaining capacity of the storage battery 1 can be accurately detected prior to the driving of the AC motor 5, and the function of limiting the discharge current of the storage battery 1 can be surely exhibited.

In this case, instead of outputting the pulse signal as described above, when the power of the entire apparatus is turned on or when the AC motor 5 is used.
In a state in which a large current is likely to flow, such as at the time of starting, the remaining capacity of the storage battery 1 can be calculated in the same manner as described above based on the fluctuation state of the output voltage Vc of the storage battery 1 and the detection signal Ic. .

The present invention is not limited to the above-described embodiments, and is not limited to, for example, an electric vehicle, but can be applied to a wide range of devices that perform variable speed drive of an AC motor by an inverter device using a storage battery as a power source. It is applicable.

[0040]

As is apparent from the above description, in the invention according to claim 1, the upper limit value of the output current of the inverter device driven by the storage battery is reduced in accordance with the decrease in the remaining capacity of the storage battery. Since the configuration is limited, it is possible to prevent the time until the output of the storage battery reaches the final voltage when the storage battery is discharged, and it is possible to effectively prevent the use of the storage battery. It is a thing.

According to the second aspect of the present invention, the upper limit value of the output current of the inverter device, which is limited as described above, is corrected according to the temperature of the storage battery or the vicinity thereof. The effect of compensating for the performance deterioration can be obtained.

According to the third aspect of the present invention, the upper limit value of the output current of the inverter device, which is limited by the current limiting means,
Since a display device is provided for displaying an allowable range in which the upper limit value can be changed, and the upper limit value of the output current of the inverter device can be arbitrarily adjusted within the allowable range displayed on the display device, the inverter device The output current can be increased as needed, which is convenient in actual use.

According to the fourth aspect of the invention, since the rising of the acceleration command signal for the AC motor is delayed, the rising of the discharge current of the storage battery can be made gentle so that the storage battery can be used more effectively. Become.

According to the fifth aspect of the present invention, the remaining capacity detecting means is configured to detect the remaining capacity based on the fluctuation state of the output voltage and current of the storage battery at the beginning of the discharge start of the storage battery. The remaining capacity of the storage battery can be accurately detected prior to the driving of the storage battery, and the discharge current limiting function of the storage battery can be reliably exerted.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing an electrical configuration of a first embodiment of the present invention.

FIG. 2 is a timing chart for explaining operation 1

FIG. 3 is a timing chart for explaining operation 2

[Fig. 4] Signal waveform diagram of each part

FIG. 5 is a view corresponding to FIG. 1 showing a second embodiment of the present invention.

FIG. 6 is a view corresponding to FIG.

FIG. 7 is a view corresponding to FIG. 6 showing a modified example of the second embodiment.

FIG. 8 is a diagram corresponding to FIG. 1 showing a third embodiment of the present invention.

FIG. 9 is a view corresponding to FIG.

FIG. 10 is a view corresponding to FIG. 4 showing a fourth embodiment of the present invention.

FIG. 11 is a view corresponding to FIG. 4 showing a fifth embodiment of the present invention.

FIG. 12 is a view corresponding to FIG. 4 showing a sixth embodiment of the present invention.

[Explanation of symbols]

In the figure, 1 is a storage battery, 4 is an inverter device, 5 is an AC electric motor, 8 is a control circuit, 9 is a current sensor, 10 is an arithmetic circuit (remaining capacity detecting means), 11 is a signal generating circuit (current limiting means), 11a. Is a temperature sensor, 13 is an adjusting device, and 14 is a display device.

Claims (5)

[Claims] 1. A power supply device for an electric motor, comprising an inverter device using a storage battery as a power source, wherein an AC motor is driven at a variable speed by an output of the inverter device, wherein the storage battery is based on an output voltage and a current of the storage battery. A remaining capacity detecting means for detecting the remaining capacity of the inverter device, and a current limiting means for limiting the upper limit value of the output current of the inverter device so as to become smaller in accordance with a decrease in the remaining capacity detected by the remaining capacity detecting means. A power supply device for an electric motor, characterized by being provided. 2. A temperature sensor for detecting the temperature of the storage battery or the vicinity thereof, wherein the current limiting means is configured to correct the upper limit value of the output current of the inverter device according to the temperature detected by the temperature sensor. The power supply device for an electric motor according to claim 1, wherein 3. An upper limit of the output current of the inverter device, wherein the current limiter is configured to be able to change and set the upper limit value of the output current of the inverter device within a predetermined allowable range. A display device that displays the value and its allowable range; and an adjusting device that can arbitrarily adjust the upper limit value of the output current of the inverter device that is limited by the current limiting means within the allowable range displayed on the display device. The power supply device for an electric motor according to claim 1, wherein 4. A delay means for extending the acceleration time of the AC motor through the inverter device by delaying the rising of the acceleration command signal when receiving the acceleration command signal of the AC motor. The power supply device for an electric motor according to claim 1. 5. The remaining capacity detecting means is configured to detect the remaining capacity of the storage battery on the basis of the fluctuation state of the output voltage and the current at the beginning of discharging the storage battery. Power supply for electric motor.