JP2001224190A - Regenerative control circuit of dc separately exited shunt motor and its regenerative control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent breakdown of a switching element by a method, where a regenerative current and a field current flow according to a command and brake torque is constant, while a battery current is not decreased, and an excessive regenerative current is restrained, when the battery voltage is decreased. SOLUTION: When the battery voltage is not decreased, the regenerative current and the field current are ensured according to the command, and the brake torque is controlled to be constant as normal. When the battery voltage is decreased, an overcurrent flows in a current flowing element 8 for first DUTY control, even if other switching elements are turned off, in normal case. By performing control in such a manner that DUTY of a current flowing element 7 for second DUTY control is decreased, the overcurrent flowing in the element 8 is restrained and breakdown of the element 8 can be prevented. The current flowing element for the first DUTY control is an IGBT, which is apt to be broken down by an overcurrent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a regenerative control circuit and a regenerative control method for a DC shunt separately excited motor.
The present invention relates to a regenerative control circuit and a regenerative control method for a DC shunt separately excited motor that uses an IGBT and prevents an excessive current from flowing to the IGBT and destroying it.

[0002]

2. Description of the Related Art A forklift uses a DC shunt separately excited motor powered by a battery. The circuit of such a battery fork is provided with a regenerative braking circuit that returns a regenerative current to the battery during braking. In such a regenerative braking circuit, as shown in FIG. 5, a switching element 102 is connected in parallel to a motor armature 101, controls a field current according to the motor speed, and generates a regenerative current flowing through the control. Is not sufficiently obtained, the switching element 102 is turned on between the motor terminals (DUTY1
00%), the armature current and the field current are controlled so that the regenerative current as instructed is obtained, and the brake torque during regeneration is constant. When the battery voltage drops, the switching element 102
Even in the case of the FF, the regenerative current becomes excessive and the switching element 103 may be destroyed.

While the battery voltage is not reduced, the regenerative current and the field current flow as instructed and the brake torque is constant, but when the battery voltage is reduced, switching is performed by suppressing the regenerative current from becoming excessively large. It is desired to prevent the element 103 from being broken.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a regenerative current and a field current as instructed as long as the battery voltage is not reduced, so that the brake torque is constant, but the battery voltage is reduced. An object of the present invention is to provide a regenerative control circuit and a regenerative control method for a DC shunt separately excited motor capable of preventing an excessive increase in a regenerative current and preventing destruction of a switching element.

[0005]

Means for solving the problem are described as follows. The technical items appearing in the expression are appended with numbers, symbols, and the like in parentheses (). The numbers, symbols, and the like are technical items that constitute at least one embodiment or a plurality of the embodiments of the present invention, in particular, the embodiments or the examples. Corresponds to the reference numerals, reference symbols, and the like assigned to the technical matters expressed in the drawings corresponding to the above. Such reference numbers and reference symbols clarify the correspondence and bridging between the technical matters described in the claims and the technical matters of the embodiments or examples. Such correspondence / bridge does not mean that the technical matters described in the claims are interpreted as being limited to the technical matters of the embodiments or the examples.

A regenerative control circuit for a DC shunt separately excited motor according to the present invention comprises a battery (1) and both poles (3, 4) of the battery (1).
A motor formed by an armature (5) and a field winding (6) connected in parallel between the armature (5) and an armature (5) connected in series with the armature (5) between both poles (3, 4); ), A first DUTY control energizing element (8) for controlling an armature current (Ia) flowing therethrough, a second DUTY control energizing element (7) for controlling a field current flowing through a field winding (6), and Child current (I
a) for detecting the current flowing through the second duty control energizing element (7) when the sensor (11) detects that the armature current (Ia) during regeneration is equal to or greater than a specified value. Decrease. When the battery voltage is not reduced, the control to secure the regenerative current and the field current as instructed to keep the brake torque constant is the same as the conventional control. Even if (102 in FIG. 5) is temporarily turned off, an excessive current flows through the first DUTY control energizing element (8), but the second DUTY control energizing element (7).
, The overcurrent flowing through the first DUTY control energizing element (8) can be suppressed and its destruction can be prevented. In particular, the first duty control energizing element is an IGB that is highly likely to be destroyed by an overcurrent.
T. Such a motor is particularly effective when used in a forklift.

[0007] A regenerative control method for a DC shunt separately excited motor according to the present invention includes measuring a regenerative current (Ia) and reducing a field current (If) when the regenerative current is equal to or greater than a specified value. Including. The reduction is to be performed by a PWM command.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Corresponding to the drawings, an embodiment of a regenerative control circuit for a DC shunt separately excited motor according to the present invention is mounted on a forklift and provided with a battery and a current control circuit. The battery 1 is connected to the current control circuit 2 in series. The current control circuit 2 includes a positive circuit line 3 of the battery 1 and a negative circuit line 4 of the battery 1. An armature 5 and a field winding 6 are connected in parallel between the positive side circuit line 3 and the negative side circuit line 4 to excite the armature winding and receive a thrust.

The field winding 6 is bridge-connected between four duty control energizing elements 7 which open and close, respectively. Between the positive side circuit line 3 and the negative side circuit line 4, an IGBT 8 for DUTY control is connected in series to the armature 5. IGBT 8 for duty control and positive side circuit line 3
And a duty control element 9 is connected to the armature 5 in parallel.

[0010] Two current detection sensors are provided.
One current detection sensor is an armature current sensor 11 that detects an armature current flowing through the armature 5. Another current detection sensor is a field current sensor 12 that detects a field current flowing through the field winding 6.

If the battery voltage has not dropped,
As shown in FIG. 2, the DUT of the DUTY control element 9
By controlling the regenerative current Ia and the field current If only by the DUTY control of the Y control and the DUTY control energizing element 7 or only the DUTY control of the DUTY control energizing element 7, the regenerative braking torque is kept constant as before. Is controlled. When the battery voltage decreases, as shown in the flow chart of FIG. 3, the regenerative current Ia exceeding the reference value Ia ″ set lower than the limit value Ia ′ is applied to the armature current sensor 11.
(Step S1). Ia "<Ia <I
If it is a '(step S2), the PWM command is issued to the DUT so as to decrease the DUTY of the DUTY control energizing element 7.
The excitation force applied to the windings of the armature 5 from the field windings 6 is reduced by applying the currents to the Y control energizing elements 7 (step S3) to reduce the field current If. This decrease in the excitation force reduces the line current Ia. This decrease is due to DUTY
The control IGBT 8 can be protected from overcurrent to protect the duty control IGBT 8.

[0012]

A regenerative control circuit and a regenerative control method for a DC shunt separately excited motor according to the present invention are used for DUTY control in which regenerative current flows by preventing excessive regenerative current even when the battery voltage drops. The element can be effectively protected.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a regenerative control circuit of a DC shunt separately excited motor according to the present invention.

FIG. 2 is a circuit diagram showing an operation state of a part of FIG. 1;

FIG. 3 is a flowchart illustrating an embodiment of a regeneration control method for a DC shunt separately excited motor according to the present invention.

FIG. 4 is a circuit diagram showing a known device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Battery 3, 4 ... Bipolar 5 ... Armature 6 ... Field winding 7 ... Second DUTY control energizing element 8 ... First DUTY control energizing element 11 ... Sensor Ia ... Armature current If ... Field current

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Shinichi Kobayashi 1 Nagoya Equipment Works, Iwazuka-cho, Nakamura-ku, Nagoya City, Aichi Prefecture Mitsubishi Heavy Industries, Ltd. No. 10 Mitsubishi Heavy Industries, Ltd. Nagoya Aerospace Systems Works F-term (reference) 3F333 AA02 AB13 DB07 FA18 FA20 FA32 FE04 FE09 5H115 PA08 PG05 PI16 PO17 PU04 PU06 PV23 QI04 RB19 RB20 SE03 TO12 TU02 5H530 AA14 BB21 CC23 CD33 DD16 CF15 DD15 DD28 EE05 EF01 5H571 AA02 BB07 CC04 DD01 DD02 EE08 FF04 GG04 HA10 HB02 HB04 HD02 LL22 MM02

Claims (5)

[Claims] 1. A motor formed by a battery, an armature and a field winding connected in parallel between both poles of the battery, and a motor connected in series with the armature between the poles and connected to the armature. A first DUTY control energizing element for controlling a flowing armature current; and a second DUTY for controlling a field current flowing through the field winding.
A control energizing element and a sensor for detecting the armature current are included. When the sensor detects that the armature current at the time of regeneration is equal to or greater than a specified value, the duty of the second DUTY control energizing element is Decreasing DC regenerative motor regenerative control circuit. 2. The regenerative control circuit according to claim 1, wherein the first duty control energizing element is an IGBT which is IGBT which may be destroyed by an overcurrent. 3. The regenerative control circuit according to claim 1, wherein the motor is a DC shunt separately excited motor mounted on a forklift. 4. A regenerative control method for a DC shunt separately excited motor, comprising: measuring a regenerative current; and reducing a field current when the regenerative current is equal to or greater than a specified value. 5. The method according to claim 3, wherein said reducing is performed by a PWM command.