JPH08322103A - Motor drive apparatus - Google Patents

Abstract

PURPOSE: To save energy when a motor is driven by dividing a plurality of batteries in series into two or more units, connecting the units in parallel, connecting both ends to the motor, and regenerating the generating power of the motor. CONSTITUTION: When a motor 2 is driven, switches 3 are set in a discharge mode, and battery units 1a and 1b are connected in series. The voltage of 12V is supplied to the motor 2 from both ends. Meanwhile, when the motor 2 is braked, the switches 3 are turned to the side of a charging mode, and the battery units 1a and 1b are connected in parallel. The voltage between both ends is set at 6V, which is lower than 12V of the rated drive voltage of the motor 2. When the generated voltage by the motor 2 is sufficiently higher than 6V, the generated power of the motor 2 charges the battery units 1a and 1b through a reverse-current preventing diode 4 and a current limiter circuit 5. Thus, the energy is regenerated, and the drive time is elongated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor drive device for driving an electric motor by using the stored electric power of a battery, such as an electric vehicle, an electric forklift truck, an electric bicycle, and the like, and particularly to electric power generated by the electric motor when braking the electric motor. The present invention relates to an electric motor drive device that recycles electricity into a battery to save energy and extend the drive time.

[0002]

2. Description of the Related Art While an electric motor and wheels are mechanically connected,
Separate the motor from the power supply and connect an electrical load to cause the load to consume the power generated by the rotation of the armature,
A method of braking the electric motor by the reverse torque generated at this time is known. However, it is difficult to charge the drive battery because the generated voltage of the electric motor is lower than the drive rated voltage and fluctuates in a wide range depending on the running condition when the electric power generated by the electric motor is collected and stored and used as power for the electric power. Not implemented because there is. To increase the generated voltage during braking higher than the drive rated voltage, there is a method of increasing the rotation speed of the electric motor by providing a speed increasing gear between the wheel and the electric motor, or a method of boosting the generated voltage of the electric motor with a booster. Conceivable,
There are problems that the device is large and heavy, and that voltage control is difficult. If the power consumed by driving the mechanism added to regenerate the power becomes larger than the regenerated power, there is no point in regenerating the power.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is an electric motor drive device for driving an electric motor using the stored power of a battery, which has a small and lightweight structure and is used during braking. The purpose of the present invention is to save energy and extend the driving time by collecting and storing the electric power generated by the electric motor and reusing it as power for driving.

[0004]

In order to achieve the above object, in the present invention, in an electric motor drive device for driving an electric motor by a plurality of storage batteries, all of the plurality of storage batteries are connected in series, and both ends of the storage battery are connected in series. A discharge mode for supplying driving power to an electric motor and the plurality of storage batteries connected in series are divided into two or more battery units, the battery units are connected in parallel, and both ends thereof are connected to the electric motor to generate electric power from the electric motor. It is characterized in that a switch means for switching between a charging mode in which electric power is regenerated to the storage battery is provided.

In a preferred embodiment of the present invention, the switch means divides the plurality of storage batteries in the charging mode into two battery units having a rated voltage which is one half of that in the discharging mode. To do. Further, in another preferred embodiment, means for detecting a generated voltage of the electric motor in the charging mode is further provided, and the switch means further detects a generated voltage of the plurality of storage batteries according to the detection output. N for battery units with lower rated voltage
(However, n is a divisor larger than 2 which is the number of the storage batteries.)

[0006]

According to the present invention configured as described above, a storage battery for driving an electric motor of an electric motor driven vehicle or the like is divided into a plurality of battery units having a voltage lower than the drive rated voltage of the electric motor,
When discharging (when driving the electric motor), connect the battery units in series to drive the electric motor, and when charging (when braking the electric motor), change the connection between the battery units so that the generated voltage of the electric motor becomes higher than the battery voltage. Then, the electric power generated by the electric motor can be regenerated by inertial traveling or downhill traveling. That is, when a motor-driven vehicle travels with inertial energy when traveling on a downward slope or the like without using electric power, it is possible to collect the electric power generated in the electric motor in a driving power supply battery and reuse it as driving power. Furthermore, in power-assisted electric bicycles, etc. that drive the electric motor to lighten the pedal effort only when a certain amount of force is applied to the pedal when climbing uphill or running on level ground, the pedal may be used when the amount of battery charge is insufficient. You can also charge the battery manually.

[0007]

Embodiment 1 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a DC motor drive device according to an embodiment of the present invention. In the figure, 1a and 1b are battery units each having a rated voltage of 6 V, and 2 is a rated voltage of 12 V.
A DC motor 3 for V (3a, 3b, 3c) is a switch for switching between a discharging mode in which the battery unit 1a, 1b drives the motor 2 and a charging mode for charging the battery unit 1a, 1b in the motor 2; The diode 5 is a current limiting circuit.

When the motor is driven, the changeover switch 3 is changed over to the discharge mode side shown by the dotted line in FIG. This allows
The battery units 1a and 1b are connected in series, and a voltage of 12V is supplied to the motor 2 from both ends thereof.

On the other hand, during motor braking, the changeover switch 3
Is switched to the charging mode side shown by the solid line in FIG. As a result, the battery units 1a and 1b are connected in parallel, and the voltage across the battery units is 12V which is the drive rated voltage of the motor.
The voltage becomes lower than 6V, and while the generated voltage of the motor 2 is sufficiently higher than 6V, the electric power generated by the motor 2 passes through the backflow prevention diode 4 and the current limiting circuit 5 to the battery unit 1
A and 1b are charged. When the generated voltage of the motor 2 falls below the sum of the terminal voltage of the battery units 1a and 1b connected in parallel and the voltage drop of the backflow prevention diode 4 and the current limiting circuit 5, the charging is terminated. The backflow prevention diode 4 is for preventing current from flowing back from the battery units 1a, 1b to the motor 2 when the generated voltage of the motor 2 is lower than the terminal voltage of the battery units 1a, 1b in the charging mode. . Further, in the current limiting circuit 5, an excessive current flows into the battery units 1a and 1b to deteriorate or destroy the storage batteries forming the battery units 1a and 1b, or the motor 2 is suddenly braked (a sudden braking is applied). In order to prevent this, the charging current is limited to a predetermined current value or less. If the current limiting circuit 5 is not provided, the current limiting element of the circuit is only a small resistance such as a wiring resistance and a winding resistance of the motor 2, and when the motor 2 is rotating at a rated speed of about 12V of the motor 2 and about 6V of the battery unit. A current obtained by dividing the difference of the above by the minute resistance flows into the battery unit. In the current limiting circuit 5, the transistor 51 is completely turned on when the charging current is equal to or lower than the predetermined current value. However, when the current exceeds the predetermined current value, the transistor 51 operates in the active region and functions as a resistor to limit the charging current. As the current limiting circuit, a resistor may be connected in series with the backflow prevention diode. In this case, the power regeneration efficiency is reduced, but the circuit configuration is simplified. Further, when the capacity (allowable current value) of the battery unit is sufficiently large and the degree of motor braking is not too large from the viewpoint of the entire device, the current limiting circuit 5 can be omitted.

The change-over switch 3 may be operated independently, but when the motor drive device of the present embodiment is applied to an electric vehicle, it can be interlocked with its brake. In this case, for example, when the brake is operated, the changeover switch 3 is operated within the play range of the brake.
Should be switched to the charging state. Furthermore, a variable resistor may be used as the current detection resistor 52 of the current limiting circuit 5 or the substitute resistor, and the resistance value may be changed in conjunction with the brake to adjust the brake amount by the electric motor.

[0011]

[Embodiment 2] FIG. 2 shows the configuration of a DC motor drive apparatus according to another embodiment of the present invention. The apparatus according to the first embodiment has a motor 2
When the generated voltage of the battery is about 7V or less, the battery unit 1a,
Charging to 1b is stopped, and electric power of about 7V or less cannot be regenerated. In the second embodiment, a 12V battery is used as a 2V battery unit (in this embodiment, an individual cell) 1.
-1, ..., 1-6 divided into 6 parts, 6 battery units are connected in series when the motor is driven, and 12V output is obtained. At the time of motor braking, 3 units are connected in series and 2 units are connected in parallel to 6V. Motor 2
As the power generation voltage decreases, 2 in series, 3 in parallel, 4V,
All terminals are connected in parallel at 2V and the battery terminal voltage is lowered.

In FIG. 2, 6 is a voltage identification circuit, 7 is a battery switching control circuit, and 8 is a battery switching circuit. The voltage identification circuit 6 includes a rechargeable standard battery 61, a comparator 6
2 to 64 and AND circuits 65 and 66. A
In the ND circuits 65 and 66, a circled input terminal indicates an inverted signal of the input signal, and a non-circled input terminal indicates that the input signal is used as it is to perform a logical product operation. The battery switching control circuit 7 has six 2-input O
An R circuit is provided. The battery switching circuit 8 includes switching elements A _{1 to} A ₄ , B _{1 to} B ₂ , C _{1 to} C ₂ , and D _1.
To D ₂ , E, F _{1 to} F ₄ and battery units 1-1 to 1
-6 is provided. As the switching element, an IC using a MOS type power FET, a relay contact or the like can be used. Here, in order to prevent the battery from being short-circuited due to variations or deviations in the ON / OFF time of the switching element, it is turned OFF immediately after the ON signal disappears when OFF, but delayed by several μs after the ON signal is input when ON. A switching IC with a delay circuit that turns on is used. The diode 9 and the small-capacity storage battery 10 are for supplying the operating power supply Vcc of the voltage identification circuit 6, the battery switching control circuit 7, and the battery switching circuit 8.

Next, the operation of the apparatus shown in FIG. 2 will be described. When the changeover switch 3 is set to “drive”, the charging of the rechargeable standard battery 61 is started, and at the same time, the signal “1” is output to the terminal d of the voltage identification circuit 6. Then, the battery switching control circuit 7 responds to the signal at the terminal d of the voltage identification circuit 6 and outputs an ON signal to the terminals C, D and E via the logic circuit. Thereby, the switching elements C _{1 to} C ₂ , D of the battery switching circuit 8
_{1 to} D ₂ and E become conductive, and battery units 1-1 to 1-
6 are all connected in series as shown in FIG.
It outputs the DC power of 12V required for driving.

Next, when the changeover switch 3 is set to "charge",
The motor 2 functions as a generator, sends out the generated power, and at the same time, generates a braking torque according to the load. If the generated voltage of the motor 2 is 7 V or more, the voltage identification circuit 6 outputs a signal "1" to its terminal c. Then, the battery switching control circuit 7 responds to the signal "1" at the terminal c of the voltage identification circuit 6 and outputs an ON signal to the terminals B, C and D via the logic circuit.
As a result, the switching elements B _{1 to} B ₂ , C _{1 to} C ₂ and D _{1 to} D ₂ of the battery switching circuit 8 become conductive,
As shown in FIG. 4, the battery units 1-1 to 1-6 have battery units 1-1 to 1-3 and 1-4 to 1-6 connected in series, respectively, and each series circuit is connected in parallel with each other. It The three batteries connected in series and in parallel with a terminal voltage of 6 V are connected to the motor 2 via the backflow prevention diode 4, and the generated power of the motor 2 is maintained while the output voltage of the motor 2 is 7 V or more. Can be charged.

Next, when the generated voltage falls within the range of less than 7V and 5V or more, the voltage identification circuit 6 outputs a signal "1" to its terminal b.
Is output. Then, the battery switching control circuit 7 responds to the signal "1" at the terminal b of the voltage identification circuit 6 and outputs an ON signal to the terminals A, C and E via the logic circuit. Thereby, the switching elements A _{1 to} A ₄ , C ₁ of the battery switching circuit 8
~ C ₂ and E conduct, and battery units 1-1 to 1-6
2 are connected in series as shown in FIG. 5, and each series circuit is connected in parallel with each other. That is, two battery units are connected in series and 3 in parallel, the terminal voltage is 4V, and the generated power of 5V or more of the motor 2 can be charged.

Next, when the generated voltage falls within the range of less than 5V and 3V or more, the voltage identification circuit 6 outputs a signal "1" to its terminal a.
Is output. Then, the battery switching control circuit 7 responds to the signal "1" at the terminal a of the voltage discriminating circuit 6 and outputs an ON signal to the terminals A, B and F through the logic circuit. Thereby, the switching elements A _{1 to} A ₄ , B ₁ of the battery switching circuit 8
~ B ₂ and E are conducted, and battery units 1-1 to 1-6
Are connected in parallel as shown in FIG. That is, the battery unit has a terminal voltage of 2V and the motor 2
The generated power of 3 V or more can be charged.

Also in the second embodiment, the current limiting circuit as in the first embodiment can be used if necessary.

[0018]

Third Embodiment In the second embodiment, when a semiconductor switching element is used as the switching element, even if the voltage drop when one semiconductor switching element is turned on is 0.12 V, five semiconductor switching elements are battery Therefore, the total voltage drop becomes 0.6V, and the loss during driving increases by 5%. In order to prevent this, the device becomes slightly larger, but normally closed relay contacts (NC contacts) may be used as the switching elements C _{1 to} C ₂ , D _{1 to} D ₂ and E. In this case, switching the relay contact C ₁ -C ₂ (relay C) a signal F as (open to) the signal, the relay contact D ₁ to D ₂
The signal A can be used as a signal for switching (opening) the (relay D), and the signal B can be used as a signal for switching (opening) the relay contact E (relay E). Therefore, the normally open contact (NO contact) of the relay D is used as the switching elements A _{1 to} A ₄ , the normally open contact of the relay E is used as the switching elements B _{1 to} B ₂ , and the relay C is used as the switching elements F _{1 to} F ₄ . Normally open contacts can be used. FIG. 7 shows a circuit example when a relay contact is used as a switching element.

[0019]

Scope of application of the invention In the present invention, the motor may be of a so-called inner rotor type or outer rotor type. Alternatively, the rotor may be a coreless motor having no iron core. Further, it may be a so-called brushless motor using a semiconductor switching element instead of the brush. In the case of a brushless motor, normally the diodes connected in anti-parallel to each semiconductor switching element rectify the generated voltage in each winding of the motor to convert it to DC, but otherwise, rectify the voltage in each winding of the motor. Then, a rectifier circuit for supplying the battery is added.

In the present invention, the storage battery is a lead storage battery or N
Not only the i-Cd battery but any battery that can be charged and discharged may be used. Further, not only the unit cell but also a plurality of unit cells may be connected in series and / or in parallel to form one battery circuit.

In the present invention, the motor for generating power may be a plurality of motors instead of just one motor. At the time of regeneration, by connecting the motors in series, it is possible to increase the voltage of regenerative power generation, and in addition, it is possible to regenerate with one regenerative circuit as compared with the case of regenerating each motor separately.

[0022]

As described above, according to the present invention,
With a compact and lightweight structure, the battery can be charged as electric power for driving the motor by the generated voltage of the motor during braking of the motor, and energy saving of the device and extension of the driving time can be achieved. Particularly, in the electric motor drive vehicle to which the electric motor drive device of the present invention is applied, the traveling distance per charge can be extended.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a DC motor drive device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a DC motor drive device according to another embodiment of the present invention.

FIG. 3 is a circuit diagram showing a battery connection state during motor braking in the apparatus of FIG.

4 is a circuit diagram showing a battery connection state when the output voltage of the motor is lower than that in FIG. 3 during motor braking of the device in FIG.

5 is a circuit diagram showing a battery connection state when the output voltage of the motor is lower than that of FIG. 4 during motor braking of the device of FIG.

6 is a circuit diagram showing a battery connection state when the output voltage of the motor is lower than that of FIG. 5 during motor braking of the device of FIG.

FIG. 7 is a circuit diagram showing a configuration of a DC motor drive device according to still another embodiment of the present invention.

[Explanation of Codes] 1a, 1b, 1-1 to 1-6: Battery unit, 2: Motor, 3, 3a to 3c: Changeover switch, 4: Backflow prevention diode, 5: Current limiting circuit, 6: Voltage identification circuit , 7:
Battery switching control circuit, 8: Battery switching circuit.

Claims (3)

[Claims] 1. A motor drive device for driving an electric motor with a plurality of storage batteries, wherein a total number of the plurality of storage batteries are connected in series and a discharge mode in which drive power is supplied to the motor from both ends thereof is connected in series. Each storage battery is divided into two or more battery units, these battery units are connected in parallel, both ends thereof are connected to the electric motor, and switch means for switching between a charging mode for regenerating the electric power generated by the electric motor to the storage battery is provided. An electric motor drive device characterized by the above. 2. The switch means divides the plurality of storage batteries into two battery units having a rated voltage of one half of the discharge mode in the charging mode. Electric motor drive. 3. A means for detecting the power generation voltage of the electric motor in the charging mode is further provided, and the switch means sets the plurality of storage batteries to a rated voltage lower than the detected power generation voltage according to the detection output. N in the battery unit that has
The motor drive device according to claim 2, wherein (where n is a divisor greater than 2 of the number of the storage batteries).