JPH06292305A - Power source for drive motor - Google Patents

Abstract

PURPOSE:To use capacitance of a capacitor connected in parallel with a battery to a maximum limit. CONSTITUTION:A power source in which a capacitor 4 is connected in parallel with a battery 3 for supplying a DC current to an inverter 2 controls a current of the battery 3 in response to the voltage of the capacitor 4 to be detected by a capacitor voltage sensor 10 by using battery current control means 6 and capacitor current control means 8, thereby controlling the voltage of the capacitor 4 in an optimum range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive power supply device, and more particularly to a motor drive power supply device for driving a motor of an electric vehicle or the like.

[0002]

2. Description of the Related Art Generally, an electric vehicle using a motor as a power source is equipped with a battery as a DC power source, and the electric power from the battery is supplied to a brushless DC motor via an inverter for driving. Further, in order not to waste electric power, regenerative braking that returns electric power generated during braking to a battery is adopted. That is, as a power supply device,
Power is taken from the battery when accelerating or traveling at a constant speed,
It is configured to return power to the battery during deceleration.

[0003]

In such a conventional power supply device, however, the battery may be rapidly discharged and charged depending on the traveling conditions during acceleration and deceleration. When such rapid charging / discharging is repeated, there are problems that the charging / discharging efficiency is reduced and the battery life is shortened. So, from the past,
For example, as disclosed in JP-A-49-37317, a capacitor and a battery are used together,
It has been proposed to prevent overcharging and overdischarging of batteries.

FIG. 19 is a circuit diagram showing an example of a conventional power supply device. This power supply device includes a battery 103 connected to an inverter 102 that converts direct current into alternating current for driving a motor 101, and a capacitor 104 connected in parallel to the battery 103. In this power supply device, the current I supplied to the inverter 102 is
_INV is the sum of the current I _B supplied from the battery 103 and the current I _C supplied from the capacitor 104. Figure 2
0 (a) to (c) are I for a short-time overdischarge.
_INV, I _C, shows the temporal variation of _{I B, (d) ~ (} f)
_Are I _INV , I _C , and I _{B at} the time of overdischarge for a long time.
It shows the change with time. Since the capacitor 104 has a small internal resistance, it is effective for over-discharge and over-charge for a short time as shown in FIGS.

However, since the capacity of the capacitor 104 is much smaller than that of the battery 103, the capacity shown in FIG.
As shown in (f), the capacitor 1
There is a problem in that the current that can be taken out from 04 is reduced and the battery 103 is in an overdischarged state. On the other hand, when the battery 103 is overcharged for a long time, the battery 103 is overcharged. This is due to the voltage characteristics during discharge of the battery and the capacitor. That is, when a constant current is discharged from the capacitor as shown in FIG. 21A, the voltage V _C of the capacitor becomes as shown in FIG. on the other hand,
When a constant current is discharged from the battery as shown in (c), the voltage V _B of the battery becomes as shown in (d). As shown in these FIG. 21, the voltage of the capacitor drops linearly, while the voltage of the battery does not drop much.

When a battery and a capacitor are connected in parallel as shown in FIG. 19, this voltage characteristic difference causes a problem in the following point. That is, by discharging from the capacitor, V _C <<
At V _B , the capacitor cannot discharge any more, so the battery must supply all the current. Also, during charging, if V _C >> V _B , the capacitor cannot be charged. Therefore, the capacitor connected in parallel to the battery exerts its effect only in the case of V _C ≉V _B , and only a small part of the total capacitance of the capacitor. In addition, as a result, only short-time overcharge and overdischarge can be performed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a motor driving power supply device which can maximize the capacity of a capacitor connected in parallel with a battery.

[0008]

According to a first aspect of the present invention, a battery connected to a motor drive circuit, a capacitor connected in parallel to the battery, and a current for controlling the current of each of the battery and the capacitor. Control means, voltage detection means for detecting the voltage of the capacitor, and controlling the current of the battery or the capacitor by using the current control means according to the voltage of the capacitor detected by the voltage detection means The above object is achieved by providing a motor drive power supply device with a capacitor voltage control means for controlling the voltage within a predetermined range.

[0009]

In this motor drive power supply device, the voltage detection means detects the voltage of the capacitor, and the capacitor voltage control means controls the current of the battery or the capacitor using the current control means according to the detected voltage of the capacitor. By doing so, the voltage of the capacitor is controlled within a predetermined range.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a motor driving power supply device of the present invention will be described in detail below with reference to FIGS. FIG. 1 is a block diagram showing a drive control circuit of an electric vehicle using the power supply device of this embodiment. The drive control circuit includes an inverter 2 as a motor drive circuit that converts direct current from the power supply device into alternating current for driving the motor 1, and
A power supply device connected to the inverter 2 is provided. The power supply device is a battery 3 connected to the inverter 2.
And a large-capacity capacitor 4 connected in parallel to the battery 3, a battery current sensor 5 and a battery current control means 6 connected in series to the battery 3. Further, the power supply device is connected to the capacitor 4 in series with the capacitor current sensor 7 and the capacitor current control means 8, the battery voltage sensor 9 connected to both ends of the battery 3, and the both ends of the capacitor 4. A capacitor voltage sensor 10 is provided. here,
The motor 1 is, for example, a brushless DC motor, and the inverter 2 has, for example, a bridge circuit using transistors and diodes and a smoothing capacitor, and converts direct current from a power supply device into three-phase alternating current.

FIG. 2 is a block diagram showing the configuration of a control system for controlling each part of the drive control circuit of FIG. The power supply device according to the present embodiment includes an arithmetic unit 12 including, for example, a microcomputer. Outputs of the battery current sensor 5, the capacitor current sensor 7, the battery voltage sensor 9, and the capacitor voltage sensor 10 are input to the arithmetic unit 12, and various detection signals such as a motor command value, a battery remaining amount, and a vehicle speed are input. It is supposed to be entered. Here, the motor command value is a command value for determining the output of the motor in response to the driver's travel request by the accelerator sensor, the brake sensor, or the like. Further, the arithmetic unit 12 controls the inverter 2, the battery current control means 6 and the capacitor current control means 8.

FIG. 3 is a circuit diagram showing a configuration example of the battery current control means 6 and the capacitor current control means 8. In the example shown in FIG. 3A, the emitter of the transistor 13 and the collector of the transistor 14 are connected to each other, and
Connect the collector of 3 and the emitter of transistor 14,
One of the connection points is connected to the current sensors 5 and 7, and the other is connected to the battery 3 or the capacitor 4.
In this circuit, the direction of a current that can pass is determined by controlling the transistors 13 and 14 to be turned on and off, and the passing current is controlled by switching the transistors 13 and 14 at an arbitrary duty ratio. It is like this.

In the example shown in FIG. 3B, the transistor 1
3 is connected to the anode of the diode 16, the collector of the transistor 13, the cathode of the diode 16, the collector of the transistor 17 and the diode 18
Is connected to the cathode of the transistor 17, the emitter of the transistor 17 is connected to the anode of the diode 18, one of two connection points of the emitter of the transistor and the anode of the diode is connected to the current sensors 5 and 7, and the other is connected to the battery 3 or the capacitor 4. Connected to. In this circuit,
Similarly to the example of (a), the direction of the current that can pass is determined by controlling the on / off of each of the transistors 15 and 17, and the current is passed by switching the transistors 15 and 17 at an arbitrary duty ratio. The current is controlled.

Next, an outline of the operation of the power supply device of this embodiment will be described. In this embodiment, in order to maximize the capacity of the capacitor 4, the current of the battery 3 is controlled within the allowable current range of the battery 3 to control the capacitor voltage V _C within the optimum voltage range. Here, the optimum voltage range of the capacitor is set as follows. First, the capacitor allowable voltage (breakdown voltage) V _CC is the battery voltage V
Set sufficiently higher than _B. For example, when V _B = 200V, V _CC = 300V. In addition, the following reason (1),
Due to (2), it is preferable that the capacitor voltage is not much lower than the battery voltage. (1) If the capacitor voltage is lower than the motor back electromotive force (proportional to the motor speed), it cannot be used as a power source. (2) When the capacitor voltage is low, the capacity (proportional to the voltage) is also low, and overdischarge for a long time cannot be performed. Further, if the capacitor voltage is raised to approach V _CC , overcharge for a long time cannot be performed. For the above reason, the optimum voltage range of the capacitor is V _B
<And V _C <V _Cd. Note that V _Cd is determined by design.

Here, according to the capacitor voltage V _C , as shown in FIG.
The area is divided as shown in. In this figure, V _Cmax
Is the maximum operating voltage of the capacitor, V _Cmin is the minimum operating voltage of the capacitor, and when the motor 1 is a permanent magnet motor, it is equal to the motor back electromotive force (proportional to the motor speed). And
The capacitor voltage V _C is controlled so as to be within the region from V _B to V _{Cd as} much as possible. Further, the capacitor does not discharge in the region from 0 V to V _Cmin . Also, V _Cmax
The capacitor does not charge in the region from V _CC to V _CC .

In the present embodiment, the following policy (3),
In (4), the battery current is controlled. (3) For example, assuming that 35A is 1C, the maximum discharge current (for example, 4C) and the maximum charge current (for example, 1C) of the battery
The battery current is controlled so as not to exceed C). (4) As shown in FIG. 5, a region where the capacitor voltage is slightly higher than the battery voltage is set as the optimum region, and the battery current is controlled so that the capacitor voltage is within the optimum region as much as possible within the range satisfying the above policy (3). . In addition, in FIG. 5, the region is the range of the capacity of the capacitor capable of charging the battery, and the region is the range of the capacity of the capacitor capable of discharging the battery.

In this embodiment, in order to achieve the above policies (3) and (4), the battery current is controlled according to the capacitor voltage V _C as shown in FIG. In this FIG.
The solid line shows the battery discharge current, and the broken line shows the battery charge current. Alternatively, control may be performed as shown in FIG. 7 in order to increase the charge / discharge efficiency and life of the battery.

Here, an example of the operation when the control shown in FIG. 7 is performed will be described with reference to FIGS. 8 and 9. Figure 8
FIG. 4 is a characteristic diagram showing the control contents of battery discharge and charging current. In this embodiment, the discharge and charge currents of the battery are controlled so as to follow the diagram of FIG. 8 regardless of no load, driving, and regeneration. Although the diagram is set in advance, it may be corrected using parameters such as driving, regenerative current, remaining battery level, and vehicle speed at each running time.

A specific example of the method for controlling the battery current will be described below with reference to FIGS. 9 (a) to 9 (c). In these figures, the battery current control means is C _B , the capacitor current control means is C _C , and the inverter is I.
It will be referred to as NV. Example (1): When the required current I _INV is larger than the battery discharge current I _Bm . In this case, as shown in FIG. 9A, the capacitor 4 is discharged to set I _INV = I _Bm + I _C. Example (2): When the required current I _INV is smaller than the battery discharge current I _Bm . In this case, as shown in FIG. 9B, the capacitor 4 is charged so that I _Bm = I _INV + I _C. Example (3): When the capacitor voltage V _C is higher than V _Cd .
In this case, as shown in FIG. 9 (c), the battery 3 is charged from the capacitor 4 so that I _C = I _GBm (battery charging current) + I _INV . Each of the above controls is performed by monitoring the current with the battery current sensor 5 and the capacitor current sensor 7, and controlling the battery current and the capacitor current with the battery current control means 6 and the capacitor current control means 8.

Next, the contents of the control of the battery current in this embodiment will be described in detail by dividing into no load, driving and regeneration. 1. At no load At no load, the battery current is controlled according to the capacitor voltage according to the diagram shown in FIG. In FIG. 10, I _Bmax represents the maximum battery discharge current, and I _GBmax represents the maximum battery charge current. These I _Bmax , I
_GBmax is a constant, but it may be a function of the remaining battery level (or a substitute value, such as battery voltage and temperature).
Generally, the larger the remaining battery level, the larger I _Bmax ,
As I _GBmax is smaller and the battery level is smaller, I _Bmax is smaller and I _GBmax is larger. _Further , as shown in FIG. 11, the battery discharge current I _Bm and the battery charge current I _GBm may be constant values within a predetermined region, but I _Bm , I _Bm
It is preferable to lower _GBm as much as possible in terms of charge / discharge efficiency and battery life.

The contents of the control method according to FIG. 10 or 11 will be specifically described below. (1) When 0 <V _C <V _B , the capacitor 3 is charged from the battery 3. In this case, I _B = I _C = I _Bm . Control of the battery current may be performed by the battery current control means 6 as shown in FIG. 12A or by the capacitor current control means 8 as shown in FIG. 12B. (2) When V _B <V _C <V _Cd , charging / discharging is not performed.
In this case, the battery current control means 6 may interrupt the current as shown in FIG. 12C, or the capacitor current control means 8 may interrupt the current as shown in FIG. 12D. (3) When V _Cd <V _C <V _CC , the battery 3 is charged from the capacitor 4. In this case, I _B = I _C = I _GBmax
Becomes Control of the battery current may be performed by the battery current control means 6 as shown in FIG. 12 (e), or (f).
Alternatively, the capacitor current control means 8 may be used.

2. During Driving During driving, the battery current is controlled according to the capacitor voltage according to the diagram shown in FIG. Incidentally, the battery maximum discharge current I _'Bmax, maximum battery charging current I' _GBmax may be a function of the remaining battery capacity. Also, the drive current I
_It may be a function of _INV . In this case, the larger I _INV is, the larger I ′ _Bmax is. Further, since V _Cmin increases as the vehicle speed increases, it is necessary to widen the maximum region of I _Bm = I ′ _Bmax accordingly. Further, in the figure, the hatched region indicates a region where the battery discharge current is increased according to the inverter drive current I _INV .

At the time of driving, the control region is classified as shown in FIG. 14 by the capacitor voltage V _C and the inverter drive current I _INV , and the control is performed as follows. (1) Area A: I _INV is controlled so as not to enter this area. (2) Area B: The drive current is output from the battery 3 and the capacitor 4 is charged by the battery 3. In this case, I _B = I _Bm = I _INV + I _C. Here, the control of I _C is performed by the capacitor current control means 8 as shown in FIG. (3) Area C: The drive current is output from the battery 3. In this case, I _B = I _INV . Further, in this case, FIG.
As shown in (b), the capacitor current control means 8 cuts off the capacitor current. (4) Area D (D ₁ , D ₂ ): From battery 3 I _B = I
Output _Bm . The balance is output from the capacitor 4. In this case, I _C = I _INV −I _B. In the area D ₁ , FIG.
As shown in FIG. 5 (c), the battery current control means 6 controls I _B, and in the region D ₂ , the capacitor current control means 8 controls I _C as shown in (d). (5) Area E: The drive current is output from the capacitor 4 and the battery 3 is charged from the capacitor 4 when I _B = I _GBm . In this case, I _C = I _INV + I _B. Further, in this case, the battery current control means 6 controls I _B as shown in FIG. 15E, or the capacitor current control means 8 controls I _C as shown in FIG. 15F.

3. During regeneration During regeneration, according to the diagram shown in Fig. 16, the capacitor voltage
Control the battery current accordingly. The maximum battery
Discharge current I ″_Bmax, Battery maximum charging current I ″ _GBmaxIs
It may be a function of the remaining battery level, regenerative current, vehicle speed, or the like.
During regeneration, the capacitor voltage V_CAnd inverter drive current
I_INV, The control area is classified as shown in FIG.
And control as follows. (1) Area A: The regenerative current is the same as when the capacitor 4 is charged.
I_B= I_BmTo charge the capacitor 4 from the battery 3
To do. In this case, I_C= I_INV＋ I_BBecomes Also, this
In the case of, the capacitor current control is performed as shown in FIG.
I by means 8_CControl, or as shown in (b)
The battery current control means 6_BTo control. (2) Area B: The regenerative current charges the capacitor 4. This
In the case of, as shown in FIG.
The battery current is cut off by the means 6. (3) Area C: I_B= I_GBmTo charge the battery 3
It The rest is charged in the capacitor 4. In this case, I_C=
I_INV-I_BBecomes In addition, in this case, FIG.
As shown in FIG._BControl
Control. (4) Area D: The regenerative current is the same as when the battery 3 is charged.
Then, the battery 3 is charged from the capacitor 4. This place
If I_B= I_INV＋ I_CBecomes Also, in this case,
By the battery current control means 6 as shown in 18 (e),
I_BControl, or the capacitor voltage as shown in (f).
I by the flow control means 8_CTo control. (5) Area E: I should not enter this area_INVControl
To do.

Although the power source device for driving the motor of the electric vehicle has been described in the above embodiment, the present invention is not limited to the electric vehicle, and is generally applied to a device for driving a motor using a battery and a capacitor. be able to.

[0026]

As described above, according to the present invention, the voltage of the capacitor is controlled within the predetermined range by controlling the battery or the current of the capacitor according to the voltage of the capacitor. It is possible to maximize the capacity of the capacitor connected in parallel with.

[Brief description of drawings]

FIG. 1 is a block diagram showing a drive control circuit of an electric vehicle using an embodiment of a power supply device of the present invention.

FIG. 2 is a block diagram showing a configuration of a control system that controls each part of the drive control circuit of FIG.

3 is a circuit diagram showing a configuration example of a current control means in FIG.

FIG. 4 is an explanatory diagram showing division of regions according to a capacitor voltage for control in one embodiment.

FIG. 5 is an explanatory diagram showing an optimum region of a capacitor voltage in one embodiment.

FIG. 6 is a characteristic diagram showing the control contents of the battery current in one embodiment.

FIG. 7 is a characteristic diagram showing another example of control contents of a battery current in one embodiment.

FIG. 8 is an explanatory diagram for describing a specific example of control contents of a battery current in one embodiment.

9 is an explanatory diagram showing a method of controlling a current in the example of FIG.

FIG. 10 is a characteristic diagram showing the control contents of the battery current at no load in the embodiment.

FIG. 11 is a characteristic diagram showing another example of control contents of a battery current when no load is applied in the embodiment.

12 is an explanatory diagram showing a current control method according to the control content of FIG. 10 or FIG.

FIG. 13 is a characteristic diagram showing the control contents of the battery current during driving in one embodiment.

FIG. 14 is an explanatory diagram showing the division of regions for controlling the battery current during driving in one embodiment.

FIG. 15 is an explanatory diagram showing a current control method according to the control content of FIG.

FIG. 16 is a characteristic diagram showing the control contents of the battery current during regeneration in one embodiment.

FIG. 17 is an explanatory diagram showing the division of regions for controlling the battery current during regeneration in one embodiment.

FIG. 18 is an explanatory diagram showing a current control method according to the control content of FIG. 16;

FIG. 19 is a circuit diagram showing a configuration of an example of a conventional power supply device.

20 is a characteristic diagram showing a change in current during discharge in FIG.

21 is a characteristic diagram showing current-voltage characteristics when the battery and the capacitor in FIG. 19 are discharged.

[Explanation of symbols]

 1 Motor 2 Inverter 3 Battery 4 Capacitor 5 Battery Current Sensor 6 Battery Current Control Means 7 Capacitor Current Sensor 8 Capacitor Current Control Means 9 Battery Voltage Sensor 10 Capacitor Voltage Sensor 12 Computing Device

Claims (1)

[Claims] 1. A battery connected to a motor drive circuit, a capacitor connected in parallel to the battery, a current control means for controlling the current of each of the battery and the capacitor, and a voltage for detecting the voltage of the capacitor. Detecting means and capacitor voltage control for controlling the voltage of the capacitor within a predetermined range by controlling the current of the battery or the capacitor using the current control means according to the voltage of the capacitor detected by the voltage detecting means. A power supply device for driving a motor, comprising: