JP2000032603A - Motor control device and control method - Google Patents

Abstract

(57) [Problem] To provide a highly reliable motor control device and control method in which circuit elements are not destroyed when an overvoltage occurs, such as when power is cut off during operation of a traveling chopper circuit. An electric motor control device comprising a battery 1, a motor 5, 15 and a chopper circuit for the chopper transistors 8, 16 is provided. The energy generated by stopping the transistor 8 and conducting the chopper transistor 16 is transferred to the motor 15.
To protect circuit elements by suppressing overvoltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chopper control type motor control device and control method for an electric vehicle such as a battery forklift, and more particularly to a motor control device and a control method having circuit element protection means.

[0002]

2. Description of the Related Art It is known that a chopper circuit is stopped when an overvoltage is detected during a chopper operation as a protection means of a circuit element conventionally employed in a motor control device of an electric vehicle such as a battery forklift.

As described in Japanese Patent Application Laid-Open No. H08-111902, when power is cut off by a power cutoff device during operation, a diode provided in the power cutoff device in a direction opposite to the polarity of the battery. And means for protecting the circuit elements by absorbing the electric power generated in the electric motor by the main circuit by the return diode in the main circuit.

[0004]

Among the prior art techniques for protecting the circuit elements, the means for stopping the chopper circuit has been designed in consideration of the case where the power is cut off during the operation of the traveling chopper circuit. Absent. That is, if the power supply is cut off during the operation of the traveling chopper circuit, for example, there is nowhere to go for regenerative energy or the like generated in the electric motor and a very large voltage is generated. Therefore, even if the chopper circuit is stopped, the circuit elements are destroyed. There are cases.

[0005] The power supply cutoff device and the means for providing a freewheeling diode in the main circuit are considered to be effective even when the power is cut off during the operation of the traveling chopper circuit. No consideration is given to the failure mode of the provided diode. That is,
When the diode of the power cut-off device is in the short mode, even if an abnormality occurs and the power cut-off device is operated, power is supplied through the diode. is there. Further, since it is necessary to add an element such as a diode to the power supply cutoff device, the cost increases.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problem and provide a highly reliable motor control device which does not destroy circuit elements even when power is cut off during operation of a traveling chopper circuit. It is to provide at low cost.

[0007]

In order to achieve the above object, the present invention provides a traveling motor and a loading / unloading motor driven by the power of a battery power source, and a rotational speed of the traveling electric motor which is controlled by an operation amount of an accelerator. In a motor control device having a traveling chopper circuit that changes in accordance with the condition, and a loading chopper circuit that energizes the loading motor in response to operation of an operation lever, it is detected that a power supply line from the battery is cut off. Power cut-off detection means, and when the cut-off of the power supply line is detected by the power cut-off detection means during the operation of the traveling chopper circuit, the traveling chopper circuit is stopped and the cargo handling chopper circuit is operated. It is characterized by having means for conducting.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A protection device for a motor control device according to the present invention will be described below in detail with reference to the illustrated embodiment.

FIG. 1 is a circuit diagram of an embodiment of the present invention, in which the present invention is applied to a motor control device of a battery forklift. In FIG. 1, 1 is a battery,
2 is a power cutoff switch, 3 and 14 are fuses, 4 is a regenerative contactor, 5 is a running motor, 5a is an armature, 5b
Is a field winding, 6 is a forward contactor, and 7 is a reverse contactor. Reference numeral 8 denotes a transistor of a traveling chopper circuit that changes the rotation speed of the traveling electric motor 5 according to the operation amount of the accelerator. 9 is a pre-excitation resistor, 10 is a pre-excitation transistor, 11 is a plugging diode, 12 is a traveling flywheel diode, and 13 is a regenerative diode. Reference numeral 15 denotes a cargo-handling motor, and reference numeral 16 denotes a transistor of a cargo-handling chopper circuit that energizes the cargo-handling motor 15 in accordance with an operation of an operation lever. Reference numeral 17 denotes a cargo handling flywheel diode.

Reference numeral 18 denotes a key switch, 19 denotes a forward switch, 20 denotes a reverse switch, 21 denotes an accelerator neutral switch, 22 denotes a brake switch, and 23 denotes a cargo handling switch.
24 is a constant voltage power supply circuit.

Reference numeral 25 denotes a control microcomputer (microcomputer) for controlling the traveling chopper transistor driving circuit 33, the cargo handling chopper transistor driving circuit 34, and the like. 26 is a forward switch detection circuit, 27 is a reverse switch detection circuit, 28 is a battery voltage detection circuit, 29 is an accelerator neutral switch detection circuit, 30 is a brake switch detection circuit, 31 is a cargo switch detection circuit, and 32 is a pre-excitation transistor drive. Circuit.

Control microcomputer (microcomputer)
Reference numeral 25 has a function of executing various processes by the CPU according to the motor control program stored in the memory. FIG. 2 is a block diagram showing the processing functions of the microcomputer.

In FIG. 2, reference numeral 251 denotes a chopper conduction ratio calculation processing unit for traveling, and the state of each switch (Fsw, Rsw, Accsw, Bsw) detected by the switch detection processing unit 252 and the accelerator detection processing unit 253. The duty ratio command signal αm of the traveling chopper circuit that changes the rotation speed of the traveling motor in accordance with the accelerator operation amount Acc detected in step S1 and the traveling motor current Im detected in the traveling current detection processing unit 254. Generate and output The output αm of the traveling chopper duty ratio calculation processing unit 251 is processed by the traveling chopper duty ratio output processing unit 255, and is output to the traveling chopper transistor driving circuit 33 as a control signal Sch. Also, 26
Reference numeral 1 denotes a cargo chopper flow rate calculation processing unit, which operates according to the operation amount of the operation lever detected by the operation switch detection processing unit 262 and the current Ip of the cargo handling motor detected by the cargo current detection processing unit 263. A duty ratio command signal αp for controlling the cargo chopper circuit is generated and output. This duty ratio command signal αp is output to the chopper duty ratio output processing unit 264 for cargo handling.
, And output to the cargo chopper transistor drive circuit 34 as a control signal Pch.

Reference numeral 256 denotes a power cutoff detection processing unit which detects that the power supply line from the battery has been cut off and, if the power supply line cutoff is detected during operation of the traveling chopper circuit, a conduction ratio command signal. αm is set to αm = 0 and output to the traveling chopper conduction ratio output processing unit 255 to stop the traveling chopper circuit. In addition, it generates a duty ratio command signal αp ′ and outputs it to the chopper duty ratio output processing unit 264 for cargo handling.
The cargo chopper circuit is made conductive. 257 is a timer processing unit.

FIG. 3 shows an example of the power cutoff detection processing section 256. During the operation of the traveling chopper circuit, the power cut-off detection processing unit 256 has detected in the specified time setting processing unit 2562 that the voltage detected by the battery voltage detection processing unit 2561 has continued for a specified time with a voltage equal to or higher than a specified value. In this case, the power cut-off determination processing unit 2563 determines that the power is cut off, and the processing unit for setting the chopper flow rate for traveling / handling is αm = 0, αp =
αp '.

Next, the present embodiment will be described in detail focusing on a power cutoff detection process during operation of the traveling chopper circuit. First, when the power cutoff switch 2 is turned on, and when the key switch 18 is further turned on, the constant voltage power supply circuit 24 operates and power is supplied to the microcomputer 25. This allows the microcomputer 25
Starts processing according to a program stored in the memory in the microcomputer 25 in advance.

Hereinafter, the processing of the microcomputer 25 in this embodiment will be described with reference to a program flowchart of FIG.

First, the initial setting of the microcomputer (FIG. 4, S30)
2) After the end, processing such as normal running and cargo handling is started. Switch input detection processing during normal traveling processing (S304)
In the case where it is detected that the forward switch 19 and the reverse switch 20 have been switched, or if it has been detected that the accelerator neutral switch 21 has become neutral, or if it has been detected that the brake switch 22 has been operated,
It is determined whether regeneration is possible (S306), and if regeneration is possible, regeneration control is executed (S310).

Here, when the power is cut off by the power cutoff switch 2 during regeneration, the regenerative energy generated in the traveling motor 5 goes out and the overvoltage Vh is generated. The overvoltage Vh generated here is detected by the battery voltage detection circuit 28 via the plugging diode 11, the fuse 3, and the key switch 18 (S314), and is compared with the specified voltage Vs (S316). When the overvoltage Vh is equal to or lower than the specified voltage Vs, the regenerative control process is continued, but when the overvoltage Vh is equal to or higher than the specified voltage Vs, the counter Tn is added (S320). The counter Tn is overvoltage Vh
Is continued to be added while the voltage is equal to or higher than the specified voltage Vs. When the counter Tn reaches the specified value Ts, it is determined that the battery 1 has been cut off by the power cutoff switch 2.

Here, the specified value Ts of the counter is set to a time longer than the duration of the normal chopper-off surge voltage and to such a time that the traveling chopper transistor 8 is not destroyed. It does not malfunction due to voltage. As soon as it is determined that the battery 1 has been cut off by the power cutoff switch 2, the stopping process of the traveling chopper transistor driving circuit 33 is executed (S322), and the conduction process of the cargo handling chopper transistor driving circuit 34 is executed. (S324). As a result, the regenerative energy is consumed by the electric motor 15 for cargo handling, so that the overvoltage Vh can be immediately reduced and the breakdown of the traveling chopper transistor 8 can be prevented.

Even if the electric motor 15 for cargo handling rotates while conducting, the lift or the attachment does not operate unless the lever for cargo handling is operated, and since the actual conduction time is very short, it is not possible to rotate greatly. Absent. Further, the above processing is executed after the battery 1 is shut off, but can be sufficiently executed within the time when the constant voltage power supply circuit 24 is operating.

Further, in the above embodiment, each processing is executed by software processing by the microcomputer 25. However, this processing can be executed by hardware having a circuit configuration as shown in FIG. 5, for example. That is, the comparator 35 compares the overvoltage Vh divided by the voltage dividing resistors R1 and R2 with the specified voltage Vs obtained by dividing the constant voltage from the constant voltage power supply circuit 24 by the voltage dividing resistors R3 and R4. When the overvoltage Vh becomes larger than the specified voltage Vs after a specified time Ts determined by the capacitor C1 and other resistors, the comparator 35 outputs a Hi signal. When the transistor 36 is turned on by the Hi signal, one of the multipliers 37 connected to the traveling chopper transistor driving circuit 33 becomes Lo, so that the traveling chopper transistor driving circuit 33 stops. Similarly, the Hi signal causes one of the adders 38 connected to the cargo chopper transistor drive circuit 34 to become Hi.
A signal is output to the cargo chopper transistor drive circuit 34.

As for the method of detecting the power cut-off, the overvoltage Vh in the above-described embodiment is applied to the battery voltage detection circuit 28.
In addition to the method of detecting at chopper transistors 8, 1
6 and a method of providing a cutoff detection switch 39 and a detection circuit 40 interlocked with the power cutoff switch 2 as shown in FIG. 6, for example.

Furthermore, in the above-described embodiment, the power supply cutoff during regeneration has been described as an example during the operation of the traveling chopper circuit. However, not only during regeneration but also during operation of the traveling chopper circuit due to other causes, an overvoltage occurs. It is also effective if you do.

[0025]

According to the present invention, it is possible to provide a highly reliable motor control device and a control method that do not destroy circuit elements when an overvoltage occurs, such as when power is cut off during operation of the traveling chopper circuit.

Also, the protection can be implemented by the function of the current motor control device without newly providing an element such as a diode on the vehicle side in a place other than the motor control device.
It contributes to cost reduction of vehicles.

[Brief description of the drawings]

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

FIG. 2 is a block diagram illustrating processing functions of a microcomputer.

FIG. 3 is a diagram illustrating an example of a power cutoff detection processing unit.

FIG. 4 is a program flowchart according to an embodiment of the present invention.

FIG. 5 is a circuit configuration diagram of a protection device according to an embodiment of the present invention.

FIG. 6 is a configuration diagram of a power cutoff detection switch according to an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 battery 2 power cutoff switch 3 fuse 4 regenerative contactor 5 traveling motor 5 a armature 5 b field winding 6 forward contactor 7 reverse contactor 8 traveling chopper transistor 9 preliminary excitation resistor 10 preliminary excitation transistor 11 plugging diode 12 traveling Flywheel diode 13 Regeneration diode 14 Fuse 15 Cargo motor 16 Carrier chopper transistor 17 Cargo flywheel diode 18 Key switch 19 Forward switch 20 Reverse switch 21 Accel neutral switch 22 Brake switch 23 Cargo switch 24 Constant voltage Power supply circuit 25 Microcomputer 26 Forward switch detection circuit 27 Reverse switch detection circuit 28 Battery voltage detection circuit 29 Accelerator neutral switch detection circuit 0 Brake switch detection circuit 31 Cargo handling switch detection circuit 32 Pre-excitation transistor drive circuit 33 Traveling chopper transistor drive circuit 34 Cargo handling chopper transistor drive circuit 35 Comparator 36 Transistor 37 Multiplier 38 Adder 39 Cutoff detection switch 40 Cutoff detection switch Detection circuit

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiroshi Katada 2520, Ojitakaba, Hitachinaka-shi, Ibaraki Co., Ltd.Automotive Equipment Division, Hitachi, Ltd. (72) Nobuyoshi Takahashi 2477 Takaba, Hitachinaka-shi, Ibaraki Stock Exchange Inside Hitachi Car Engineering Co., Ltd. (72) Inventor Hiroyuki Yamada 2477 Takaba, Hitachinaka-shi, Ibaraki Prefecture F-term in Hitachi Car Engineering Co., Ltd. JC12 JC13 KA01 KB05 KD03 KD04 5H571 AA02 BB07 CC04 DD03 FF04 GG04 GG05 HA08 HB01 HD02 JJ03 KK06 LL22 LL23 MM03

Claims (5)

[Claims] A traveling motor driven by electric power of a battery power supply and a loading / unloading motor; a traveling chopper circuit for changing a rotation speed of the traveling electric motor in accordance with an operation amount of an accelerator; An electric motor control device having a chopper circuit for loading and unloading the electric power in response to an operation of an operation lever, comprising: a power cutoff detecting unit for detecting that a power supply line from the battery is cut off; An electric motor control device comprising: means for stopping the traveling chopper circuit and conducting the cargo chopper circuit when the power supply line cutoff is detected by the power supply cutoff detecting means. 2. The motor control device according to claim 1, wherein
The motor control device according to claim 1, wherein the power cut-off detecting means determines that the power is cut off when the voltage detected by the battery voltage detecting means has continued for a specified time with a voltage equal to or higher than a specified value. 3. The motor control device according to claim 1, wherein
The motor control device according to claim 1, wherein the power cutoff detecting means detects a signal of a power cutoff switch interlocked with a device that cuts off power provided in a power supply line from the battery. 4. A driving motor and a loading / unloading motor driven by electric power from a battery power source, a traveling chopper circuit for changing a rotation speed of the driving motor in accordance with an operation amount of an accelerator, and the loading / unloading motor. An electric motor control having a cargo chopper circuit for energizing according to operation of an operation lever, and a constant voltage diode for surge protection between a collector and a base of a motor energizing transistor constituting the traveling chopper circuit and the cargo chopper circuit. The motor control device according to claim 1, wherein a protection voltage of the traveling chopper circuit transistor by a constant voltage diode is higher than a protection voltage of the cargo handling chopper circuit transistor by a constant voltage diode. 5. A traveling motor and a loading / unloading motor driven by electric power of a battery power source, a traveling chopper circuit for changing a rotation speed of the traveling electric motor in accordance with an operation amount of an accelerator, and the loading / unloading motor. A method of controlling a motor by a motor control device having a cargo chopper circuit for energizing in response to an operation of an operation lever, comprising detecting a power supply line from a battery being cut off by a power cutoff detecting means, A method of controlling an electric motor, comprising: stopping the traveling chopper circuit and conducting the cargo chopper circuit when the power supply line cutoff is detected by the power supply cutoff detecting means during operation of the circuit.