JP2003348868A - Dynamic brake circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dynamic brake circuit which can reduce the size by using a small power diode for OR without using a power large-sized diode. <P>SOLUTION: The dynamic brake circuit of a motor 22 driven by a servo driver comprises a switch means 23 for taking the induced voltage of the motor connected to the bridges 1 to 6 of transistors by diodes 13 to 15 for OR, to reduce its voltage to a low potential N when a controller is normal, or inputting the voltage to the base of the transistor of a lower stage of a diode bridge when the controller stops the operation to turn on the transistor of the lower stage to electrically short-circuit the motor wirings 24 to 26. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic braking system in which a synchronous motor or a DC servo motor is driven by a servo drive circuit, and the output of the driven motor is connected to a heavy load when power is not supplied.
g) to perform a dynamic brake circuit for clamping the servomotor.

[0002]

2. Description of the Related Art A conventional servo drive device performs a braking action by clamping a motor M by a circuit as shown in FIG. FIG. 2 is an example of a conventional circuit of a dynamic brake circuit using a relay. In this conventional example, the inverter circuit In is constituted by six transistors Tr and a full bridge formed by connecting a diode Db to each of the transistors Tr in antiparallel. The motor M is connected to the three-phase output of the inverter circuit In. The dynamic brake circuit supplies power to the inverter In—power supply line N
Is connected to one end of the B contact of the relay R, and the other end of the relay R is connected to the cathodes of three diodes Dr.
The anodes of the two diodes Dr are connected to the drive line of the motor M, respectively. Therefore, when the power is turned off and the relay R is turned on by a control command from a control unit (not shown), the motor M is driven by a combination of the three diodes Dr and the diodes Db of the inverter circuit In which is a full bridge circuit. Are in a state similar to a short circuit. In this way, the voltage obtained by ORing the terminals of the motor M with the diode Dr is short-circuited, and the motor connection is substantially made common, so that the motor M is turned off in a state where all the six transistors Tr are off. , The motor M is clamped to perform a braking action.

[0003]

However, in the above prior art, the diode Dr for ORing is a large power relay, and the short-circuiting relay R uses a large-sized power relay. There was a problem that the factor was bad and hindered miniaturization of the device.
Therefore, the present invention is a simple circuit that uses a small diode for low power without using a large power diode or power relay for power, and uses a power transistor of a bridge circuit as a dimic brake except when driving a motor. An object of the present invention is to provide an efficient dynamic brake circuit that can be easily reduced in size by using the combined system.

[0004]

According to a first aspect of the present invention, there is provided a dynamic brake circuit comprising: a bridge circuit comprising a plurality of transistors connected between DC power supply lines; By the inverter circuit consisting of the connected diode,
In a dynamic brake circuit, which supplies a current from a DC power supply through a drive line to drive a motor and applies a brake to a short circuit motor formed between the DC power supply line and the drive line when the power supply is turned off, each bridge of the transistor A first diode connected at the intersection to OR the induced voltage of the motor connection, a second diode connected in series with the first diode and the other connected to the base of the lower transistor of each of the bridges;
A switch means is provided between the connection line connecting each connection point of the first diode and the second diode and the DC power supply line. In this dynamic brake circuit, the OR of the voltage applied to the motor is obtained by an OR diode for each phase, and the switch means
Normally, when the control unit operates normally and drives the motor from the inverter bridge via the motor connection,
When the control unit stops operating by eliminating the influence on the motor drive by lowering the R voltage to a low potential, the OR voltage is applied to the bases of all the transistors at the lower stage of the transistor bridge to turn on, and the motor connection is established. It is configured to operate the dynamic brake by electrically short-circuiting, and the power transistor of the lower bridge is used together with the dynamic brake circuit, so that the motor induced voltage is short-circuited without specially providing a short-circuit power transistor. As a result, it is possible to configure a dynamic brake circuit that can be easily reduced in size with a circuit that saves parts and that is efficient.

According to a second aspect of the present invention, in the dynamic brake circuit according to the first aspect, the switch means comprises a photocoupler which is turned on / off by a signal from a control unit. In this dynamic brake circuit, since a photocoupler is used for the control signal system, electrical insulation between the power system and the control signal system can be obtained. According to a third aspect of the present invention, in the dynamic brake circuit according to the first or second aspect, the first and second dynamic brake circuits are provided.
The diode is a low power diode for driving a base of a transistor. With this dynamic brake circuit, the dynamic brake circuit can be configured with a small power diode for driving the transistor and base without using a large power diode or power relay, so that the size and cost of the device can be reduced. become.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of a dynamic brake circuit according to an embodiment of the present invention. In FIG. 1, reference numerals 1 to 6 denote transistors constituting a full-bridge transistor constituting an inverter, and reference numerals 7 to 12 denote feedback diodes connected in anti-parallel to the transistors 1 to 6, which also have a regenerative operation. Reference numerals 13, 14, and 15 denote OR low-power diodes (first diodes) for ORing the phase connection voltages of the motor, whereby the voltage at the point A is always maintained at the maximum potential of the phase connection voltages of the motor. . Reference numerals 16, 17, and 18 denote resistors connected between each phase connection of the motor and each of the diodes 13 to 15. Reference numerals 19, 20, and 21 denote backflow preventing diodes (second diodes) of a driving gate signal sent from a control unit (not shown). 22 is a motor. Reference numeral 23 denotes a photocoupler which constitutes a switch means including a photodiode and a phototransistor. When the RES signal from the control unit is L (zero), the photodiode emits light to turn on the output-side phototransistor and set the voltage at point A to N ( (The power supply), and when the RES signal is H, the voltage at the point A is cut off from N (the power supply) by the reverse operation. PHC
23, the OR potential of each phase connection voltage of the motor is turned off, and the OR potential of each phase connection voltage of the motor constitutes a full bridge.
1 and transistors 2, 4, 6 are ON
become. P is a + power supply line, and N is a − power supply line.
Reference numerals 24, 25, and 26 denote motor connection of each phase.

Next, the dynamic braking operation of the circuit shown in FIG. 1 will be described. The voltage at the point A is determined by the resistances 16 and 1 attached to each motor connection of each phase bridge.
3 through diodes 13, 14, 15 via 7, 18
The OR of the voltage of each phase is given. The voltage at the point A, which has become common, is reduced to N by the photocoupler 23 while the motor 22 is being driven, and therefore has nothing to do with the operation of the transistor bridge. Photo coupler 2
When the power supply voltage of the control unit isolated in step 3 drops and the control is not performed, the RES signal becomes H and the photocoupler 23 is turned off.
When the current flows through the diodes 19, 20, and 21 to the bases of the transistors 2, 4, and 6 in the lower stage, the respective transistors 2, 4, and 6 in the lower stage turn ON. For example, assuming that the motor connection 24 has the maximum potential and the motor connection 25 has the minimum potential with the voltage of the motor 22,
The turn-on potential is applied to the motor connection 24 → the resistor 18 → the diode 15 → the diode 21 → the base of the transistor 6, and the power transistor 6 is turned on. When the power transistor 6 is turned on, a short circuit is formed by the motor connection 24 → the power transistor 6 → the diode 10 → the motor connection 25, thereby operating as a dynamic brake. When the motor 22 stops and the induced voltage disappears, the dynamic braking operation also stops. However, when the motor 22 starts again, the circuit of the present invention operates again, and the same operation as the dynamic brake as shown in FIG. 2 is guaranteed. As described above, according to the present invention, a large-sized power diode is required in the prior art shown in FIG.
3, 14 and 15 need only a small current for driving the base, and simply add a simple and inexpensive circuit with a resistor and a diode for low power to the motor connection of each bridge. Since an efficient dynamic brake using a transistor can be configured, the size of the device can be reduced. Moreover, the transistor can be turned on by the motor voltage itself without a special power supply.

[0008]

As described above, according to the present invention,
By using only a few circuit components for low power in the bridge circuit, the power transistor of the bridge circuit can be used as a dynamic brake other than when driving the motor, and a low power diode instead of a large power diode Can form an OR, so that there is an effect that a compact, easy, efficient and inexpensive dynamic brake circuit can be formed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a dynamic brake circuit according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a conventional dynamic brake circuit.

[Explanation of symbols]

1-6 Transistor 7-12 Feedback diode 13-15 OR small power diode 16-18 for taking OR of each phase connection voltage of motor Each phase connection of motor and each diode 13-1
Resistors 19 to 21 connected between 5 Diodes 22 for preventing backflow of gate signals for driving Motor 23 Photocouplers 24 to 26 constituting switching means by photodiodes and phototransistors Motor connection P + power supply line N-power supply line

   ────────────────────────────────────────────────── ─── Continuation of front page    F-term (reference) 5H530 AA02 CC06 CE15 DD03 DD13                 5H560 BB04 EB01 HB01 HB05 SS01                       UA02

Claims (3)

[Claims] 1. A current is supplied from a DC power supply via a drive line by a bridge circuit comprising a plurality of transistors connected between DC power supply lines and an inverter circuit comprising a diode connected in anti-parallel to each of the transistors. In a dynamic brake circuit for driving a motor and applying a brake to a short-circuit motor formed between a DC power supply line and a drive line when the power is off, an OR of an induced voltage of a motor connection connected to each bridge intersection of the transistors is provided. A first diode for taking the first
A second diode connected in series with the diode, the other end of which is connected to the base of the transistor at the lower stage of each of the bridges; a connection line connecting each connection point between the first diode and the second diode; A dynamic brake circuit comprising switch means between the line and a line. 2. The dynamic brake circuit according to claim 1, wherein said switch means comprises a photocoupler that is turned on and off by a signal from a control unit. 3. The dynamic brake circuit according to claim 1, wherein the first and second diodes are low power diodes for driving a base of a transistor.