JPH0210676B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention provides a method for driving a motor by making a driving element connected to a bridge conductive, and when a power switch is turned on or off, the driving element This invention relates to a motor control circuit that prevents each pair from turning on at the same time and short-circuiting the power supply.

[Prior art]

Conventionally, for example, in a motor for opening and closing elevator doors, two pairs of driving elements were connected to a bridge, a power supply was connected between the input terminals of the bridge circuit, and the motor was connected between the output terminals of the bridge circuit. ing. A drive signal from a drive circuit is supplied to each drive element. Then, depending on whether the motor is rotated forward or reverse, the first pair of drive elements are turned on;
A second pair of driving elements is turned on.

In such a conventional motor control circuit,
When the power switch is turned on and off, the positive and negative control power supply voltages are not at their final steady state values, so
That is, the drive circuit malfunctions because the power supply to the circuit is unstable when the power is turned on or off.

Specifically, one of the first pair of driving elements and one of the second pair of driving elements are turned on at the same time, resulting in a short-circuit of the power supply.

[Summary of the invention]

This invention has been made to eliminate the above-mentioned conventional drawbacks, and when the power switch is turned on or off, if the positive control power supply voltage is larger in absolute value than the negative control power supply voltage, the driving element The present invention proposes a motor control circuit that can prevent short-circuiting of the power supply when the power switch is turned on or off.

[Embodiments of the invention]

Embodiments of a motor control circuit according to the present invention will be described below with reference to the drawings. The figure is a circuit diagram showing the configuration of one embodiment. T in the figure is a transformer, the primary winding T1 of which is connected to an AC power source (not shown) via a switch S1.

The transformer T has three secondary windings T2 to T4, and the secondary windings T2 to T4 are connected to the input ends of rectifier circuits 1 to 3, respectively. Rectifier circuit 1~
Between the output terminals of 3 are smoothing capacitors C1 to C.
3 is connected.

The field winding MF of the motor is connected in parallel to the capacitor C1.
is connected. Although the use of the motor in the illustrated embodiment is not limited, it may be used, for example, to drive the doors of an elevator to open and close.

The positive output terminal of rectifier circuit 1 is transistor Q1.
and the collectors of transistors Q3, and the negative output terminal of the rectifier circuit 1 is connected to the emitters of transistors Q2 and Q4. Transistors Q1 to Q4 are used as driving elements for driving a motor, and transistors Q1 and Q4 form a first pair, and transistors Q2 and Q3 form a second pair. A pair of first and second transistors Q1 to Q4 are bridge-connected, and the output terminal of the rectifier circuit 1 described above is connected between the input terminals thereof.

Emitter of transistor Q1 and transistor Q
The collectors of the two transistors are directly connected at a connection point P1, and the emitter of the transistor Q3 and the collector of the transistor Q4 are directly connected at a connection point P2. Both connection points P1
The armature MA of the motor is connected between and P2.

The output terminals of drive circuits 4 to 7 are connected to the bases of each of the transistors Q1 to Q4, and a freewheel diode D1 is connected between the emitter and collector of each of the transistors Q1 to Q4.
~D4 is connected.

On the other hand, the portion surrounded by the dashed line 100 is a newly added portion according to the present invention, and is a feature of the present invention.

That is, the negative output terminal of the rectifier circuit 2 and the positive output terminal of the rectifier circuit 3 are directly connected at a connection point P3, and both rectifier circuits 2 and 3 are connected in series.

The positive output end of the rectifier circuit 2 is connected to a stabilized power supply 8, a connection point P3 via a capacitor C4, and a transistor Q5 via a resistor R1.
connected to the base of.

Similarly, the negative output terminal of the rectifier circuit 3 is connected to the connection point P via the stabilized power supply 9 and the capacitor C5.
3 and to the base of a transistor Q6 via a resistor R2, and the output terminal of this stabilized power supply 9 is connected to the emitter of the transistor Q6.

The stabilized power source 8 is a stabilized power source for positive voltage, and the stabilized power source 9 is a stabilized power source for negative voltage.

Further, the transistors Q5 and Q6 are transistors for preventing the transistors Q2 and Q4 from being turned on at the same time in an unstable state when the switch S1 is on and off, respectively.

The base of the transistor Q5 is connected to a connection point P3 through a parallel circuit of a resistor R3 and a diode D5, and the emitter of the transistor Q5 is directly connected to this connection point P3. Transistor Q5
The collectors of are connected to the bases of transistors Q2 and Q4 via diodes D6 and D7, respectively.

The collector of transistor Q6 is connected to the base of transistor Q5 via resistor R3. In addition, the base of this transistor Q6 is connected to the connection point P3 via a Zener diode DZ and a resistor R4.
It is connected to the. That is, the transistor Q
5, Q6, resistors R1 to R5, diodes D5 to D
7 and the Zener diode DZ form a comparator circuit 100, which monitors a negative control voltage and turns off the transistor Q6 when the negative control voltage is below a reference value (set by the Zener diode DZ). Transistor Q5 is turned on, and the input sides (bases) of transistors Q2 and Q4 are grounded, thereby preventing transistors Q2 and Q4 from being turned on.

Next, the operation of the motor control circuit of the present invention configured as described above will be explained. Now, if switch S1 (power switch) is turned on and the negative voltage rises first, or if switch S1 is turned off and the negative voltage falls later, for example, if the drive circuits 4 to 7 are When configured with a negative power supply circuit and converts the voltage at the final stage so that the output becomes a positive or negative voltage, the output of the drive circuit is negative and must be an off signal, but the absolute value of the negative voltage is lower than that of the positive voltage. When the negative voltage does not reach the voltage value that drives the drive circuit, the drive circuit does not operate, but only the output of the final stage is inverted and an on signal is generated. Conversely, even if the drive circuit is configured with a positive power supply circuit and the voltage is converted so that the output becomes a positive or negative voltage at the final stage, if the negative voltage is below a certain value as described above, depending on the circuit configuration, The voltage conversion circuit becomes an on output, and the transistor Q
1, Q2 or Q3, Q4, the transistor Q1, Q2 or Q
3.Q4 becomes conductive and short-circuits the power supply.

Therefore, in this embodiment, by providing the comparator circuit 100 that monitors the negative control voltage,
If the negative control voltage becomes high enough to operate the drive circuit stably, that is, if it is below the reference value,
Transistor Q5 is turned off by turning off transistor Q6.
is turned on, and transistors Q1 to Q4 are turned off. When the negative control voltage is high, the transistor Q6 is turned on and the transistor Q5 is turned off, so that the transistors Q1 to Q4 operate normally. As a result of the following, the outputs of the drive circuits 4 to 7 do not rise to the "H" level in an unstable state when the switch S1 is turned on or off, thereby preventing a short circuit of the power supply.

At this time, drive circuits 4 and 7 or 5 and 6
When the output of drive circuits 4 and 7 is at "H" level, transistors Q1 and Q4 are turned on. As a result, the positive output terminal of the rectifier circuit 1 - the transistor Q1 - the armature MA of the motor - the transistor Q4 - the rectifier circuit 1
Current flows through the negative output terminal circuit, and the motor is driven normally.

Further, when the outputs of the drive circuits 5 and 6 are at "H" level, the transistors Q2 and Q3 are turned on, and the positive output terminal of the rectifier circuit 1 - the transistor Q
3-Motor armature MA-transistor Q2-A current flows through the motor armature MA through the negative output terminal circuit of the rectifier circuit 1, and the motor is normally driven.

Next, we will discuss the case where the switch S1 is turned on or off and the positive voltage rises first, or the case where the positive voltage falls later.

In this case, when the output voltage of the stabilized power supply 8 exceeds the voltage V _BE between the base and emitter of the transistor Q5, the transistor Q5 is turned on and the base of the transistor Q2 is short-circuited through the diode D6 and the transistor Q5. At the same time, the base of transistor Q4 is also shorted through diode D7 and transistor Q5.

Therefore, the transistor Q2 is not turned on at the same time when the transistors Q1 and Q4 are turned on, or the transistor Q4 is not turned on at the same time when the transistors Q2 and Q3 are turned on, thereby preventing short-circuiting of the power supply.

The same applies when the positive voltage falls later than the negative voltage. Then, the negative voltage is −
Let Vcc be the Zener voltage of the Zener diode DZ connected to the base of the transistor Q6.
Vz, if the Zener voltage Vz>Vcc/2 is set, the transistors Q6, Q
5 is not turned on and therefore transistor Q
2. The base circuit of Q4 is not shorted.

Note that in the above embodiment, two pairs of transistors Q
Although the motor is driven by connecting transistors Q1 and Q4 and Q2 and Q3 to a bridge, MOSFETs may be bridge-connected as driving elements in place of these transistors Q1 to Q4.

〔Effect of the invention〕

As described above, according to the elevator control circuit of the present invention, two pairs of driving elements are bridge-connected, power is applied to the input terminal of the bridge circuit, and a motor is connected to the output terminal to drive one pair at a time. When driving the motor by turning on the driving element, short-circuit the input circuit of one of the driving elements of each pair unless the negative control power supply voltage reaches a certain value when the power switch is turned on or off. Since the off state is established in this manner, it is possible to prevent the power supply from being short-circuited when the power supply is unstable until it starts up normally when the power switch is turned on or off.

[Brief explanation of drawings]

The figure is a circuit diagram of an embodiment of the motor control circuit of the present invention. 1-3... Rectifier circuit, 4-7... Drive circuit, 8, 9... Stabilized power supply, Q1-Q6... Transistor, D1-D6... Diode, DZ...
Zener diode, MA...motor armature,
MF...Motor field winding, S1...Switch.

Claims (1)

[Claims] 1. A transformer having a primary winding connected to an AC power supply via a switch and first, second, and third secondary windings; and a motor having first, second, and third rectifier circuits connected to the third secondary winding, and first and second input/output terminals, and an output to the first input/output terminal of the motor. The electrode is
a first switching element having input electrodes connected to the positive voltage output terminal of the first rectifier circuit; and a first switching element having input electrodes connected to the first input/output terminal of the motor.
a second switching element having output electrodes connected to the negative voltage output terminal of the first rectifier circuit; and a second switching element having output electrodes connected to the second input/output terminal of the motor.
a third switching element having input electrodes connected to the positive voltage output terminal of the first rectifier circuit; and a third switching element having input electrodes connected to the second input/output terminal of the motor.
a fourth switching element whose output electrodes are respectively connected to the negative voltage output terminal of the first rectifier circuit, whose output terminals are connected to the control electrodes of these first to fourth switching elements, and which rotates the motor in the forward direction; Sometimes, the first and fourth switching elements are made conductive and the second and third switching elements are made non-conductive, and when the motor is reversed, the second and third switching elements are made conductive and the second and third switching elements are made non-conductive. a drive circuit that makes the first and fourth switching elements non-conductive; an input electrode at the output terminal of the drive circuit; a control electrode at the positive voltage output terminal of the second rectifier circuit;
a fifth switching element having an output electrode connected to the negative voltage output terminal of the second rectifier circuit; an input electrode connected to the control electrode of the fifth switching element; and a negative voltage output terminal of the third rectifier circuit; a sixth switching element to which a control electrode and an output electrode are respectively connected; a sixth switching element connected between a control electrode of the sixth switching element and a control electrode of the fifth switching element; A motor control circuit comprising an element that becomes conductive when the voltage of the electrode becomes smaller than the voltage of the control electrode of the fifth switching element by a predetermined value or more.