JPH07154906A - Controller of dc shunt motor - Google Patents

Abstract

PURPOSE:To compensate the reduction of a field current by voltage drop by connecting a chargeable auxiliary battery of a capacitor in parallel with the series circuit composed of a shunt winding and a current control element, and supplying power from the auxiliary battery or the capacitor to the shunt winding when the voltage of a main battery power source drops at acceleration or the like. CONSTITUTION:For a motor, the armature A and the shunt winding F are normally supplied with currents by means of a main battery power source E, according to the conduction control of power transistors Q1 and Q2, and the armature A is rotated by a field magnetic flux. At the same time, the auxiliary battery or the capacitor C is charged with electricity by the main battery power source E. And, when the voltage of the main battery source E drops temporarily at starting, climbing hill, or at acceleration, etc., a shunt field winding F is supplied with a current by the auxiliary battery or the capacitor C. Hereby, the magnetic flux of a field can be secured by compensating the reduction of the field current due to the voltage drop of the main battery source E.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a controller for a DC shunt winding motor used for driving a forklift or an electric vehicle driven by a battery.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, a controller for a DC shunt winding motor for driving a forklift or the like has been known. The control device includes an armature A and a shunt field winding F, and transistors (current control elements) Q1 and Q2 that are connected in series to each of them and configure a chopper that controls a current flowing through each. However, the respective series circuits are connected in parallel to the battery power source E via the switch SW. In addition, armature A and shunt field winding F
The diodes D1 and D2 are connected in parallel with the above.
A control signal of the controller is input to the bases of the transistors Q1 and Q2.

In such a control device, the field current decreases due to a temporary drop in the voltage of the battery power source E at the time of starting, climbing a slope, or performing a sudden acceleration. The field magnetic flux is reduced, which reduces the back electromotive force of the armature, increases the armature current, and heats the motor.
Due to this temperature rise, the resistance of the field winding is increased, so that the field current is further reduced and the operating characteristics are exhibited, resulting in poor efficiency. In order to eliminate as much as possible the undesired phenomenon such as the heat generation of the motor due to the decrease of the field current at the time of acceleration, the voltage applied to the field winding is lowered by the chopper control for the field at steady state. Is set to.

[0004]

However, in the conventional apparatus as described above, in a vehicle type having a low battery voltage, such as a forklift that is driven while an operator walks with him, the rated voltage of the field winding is If the setting is made to include the fluctuation of the battery voltage, the field current becomes large and a large-capacity field chopper is required, which is expensive. The present invention solves the above-mentioned problems, can accelerate the heat generation of the motor without increasing the heat generation, and does not require a large-capacity element for controlling the current flowing through the field winding. It is an object of the present invention to provide a control device for a DC shunt winding motor.

[0005]

In order to achieve the above object, the present invention provides a DC shunt winding having an armature and a shunt field winding, and a current control element for controlling a current flowing through each of them. In a motor control device, a series circuit of an armature and a current control element, a backflow prevention diode, a shunt field winding, and a series circuit of a current control element are connected in parallel to a main battery power source, In addition, an auxiliary battery or capacitor that can be charged in parallel is connected to the series circuit of the shunt field winding and the current control element, and this auxiliary battery or capacitor is used as the field power source when the voltage of the main battery power source drops. It is the one.

[0006]

According to the above construction, the auxiliary battery or the capacitor is charged from the main battery power source in the normal time, and the auxiliary winding or the capacitor supplies power to the shunt field winding when the voltage of the main battery power source drops during acceleration. . This allows
The magnetic field flux can be secured by compensating for the decrease in the field current due to the voltage drop.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A controller for a DC shunt motor for driving a walking forklift according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram of the control device, and FIG. 2 is a block diagram of a controller portion for controlling a current control element in the circuit. The armature A of the DC shunt winding motor is connected in series with a current detection resistor r1 and a power transistor Q1 which constitutes a chopper as a current control element for controlling the current flowing through the armature A. The winding F is connected in series with a current detection resistor r2 and a power transistor Q2 that constitutes a chopper as a current control element that controls the current flowing through the winding F. A protective diode D is provided in parallel with each of the armature A and the shunt field winding F.
1, D2 are connected.

The series circuit including the armature A is connected in parallel to the main battery power source E via the switch SW, and the series circuit including the shunt field winding F includes the backflow prevention diode D3. It is connected in parallel to the main battery power source E via the series circuit including the armature A via the above. Furthermore, an auxiliary battery or a capacitor C that can be charged in parallel is connected to a series circuit including the shunt field winding F. The backflow prevention diode D3 is connected from the main battery power source E in a direction that allows the energization of the shunt field winding F and the charging current to the auxiliary battery or the capacitor C to flow. This auxiliary battery or capacitor C acts as a field power source when the voltage of the main battery power source E drops.

The control output of the controller 11 shown in FIG. 2 is connected to the bases B1 and B2 of the power transistors Q1 and Q2. A travel instruction signal from the accelerator 12 of the forklift is input to the controller 11, and a detection signal from a current detector including the current detection resistors r1 and r2 is input to the controller 11, and the controller 11 is based on these input signals. It outputs a predetermined signal for controlling the power transistors Q1 and Q2.

In the above structure, the motor is energized from the main battery power source E to the armature A and the shunt field winding F in the steady state according to the conduction control of the power transistors Q1 and Q2. The child A is rotationally driven. At the same time, the auxiliary battery or the capacitor C is charged from the main battery power source E. Then, when the voltage of the main battery power source E temporarily drops at the time of start-up, uphill or acceleration, power is supplied to the shunt field winding F from the charged auxiliary battery or the capacitor C. As a result, it is possible to compensate for the decrease in the field current due to the voltage drop of the main battery power source E and to secure the magnetic flux of the field. Therefore, heat generation of the motor due to the decrease of the field current at the time of acceleration is eliminated and the motor efficiency is prevented from decreasing.

Further, according to the present invention, since it is not necessary to set the rated voltage of the field winding F including the voltage fluctuation of the main battery power source E, the field current does not unnecessarily increase, Therefore, the power transistor Q2 for controlling the field current is
There is no need to use a large-capacity one, and it is cheap. Further, in the separately excited motor that excites the shunt field winding with another power source, a separate charger for charging the field power source is required, but such a charger is not required in the present invention. .

[0012]

As described above, according to the control device for a DC shunt winding motor of the present invention, an auxiliary battery or a capacitor that can be charged in parallel is connected to the series circuit of the shunt field winding and the current control element, When the voltage of the main battery power source drops during acceleration, power is supplied to the shunt field winding from the auxiliary battery or capacitor, so it is possible to compensate for the decrease in field current due to the voltage drop and to reduce the field magnetic flux. Can be secured. Therefore, it is possible to accelerate the motor without increasing heat generation as in the conventional case, and it is not necessary to use a large-capacity field current control element, which is inexpensive.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a control device for a DC shunt winding motor according to an embodiment of the present invention.

FIG. 2 is a block diagram of a controller portion that controls a current control element of the device.

FIG. 3 is a circuit diagram of a conventional controller for a DC shunt winding motor.

[Explanation of symbols]

 A armature F shunt winding field winding E main battery power supply C auxiliary battery or capacitor D3 backflow prevention diode Q1, Q2 power transistor (current control element)

Claims (1)

[Claims] 1. A controller for a DC shunt winding motor having an armature, a shunt winding field winding, and a current control element for controlling a current flowing through each of them, wherein an armature is provided for a main battery power source. A series circuit of a current control element, a backflow prevention diode, a shunt field winding, and a series circuit of a current control element are connected in parallel, and the shunt field winding and the current control element are connected in series. A control device for a DC shunt motor, wherein an auxiliary battery or a capacitor that can be charged is connected in parallel to the circuit, and the auxiliary battery or the capacitor is used as a field power source when the voltage of the main battery power source drops.