JP3446125B2 - Motor control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for detecting a locked state of a three-phase AC drive motor to protect the motor. 2. Description of the Related Art When a motor is locked due to an overload condition, an excessive current flows to the motor, which is dangerous. For this reason, in order to improve the safety in using the motor, a motor control device that controls the number of rotations of the motor is provided with a lock detection function of the motor. The lock detection function of the motor detects a current value of a drive signal supplied to the winding of the motor from the control device, and when the current value exceeds a predetermined reference value, determines that the motor is in a locked state, The rotation of the motor is stopped. In such a conventional lock detection function of a motor, the lock state is detected by detecting a current value flowing through a winding of the motor. It is necessary to handle extremely large currents. For this reason, there is a problem that the circuit configuration becomes complicated. An object of the present invention is to solve the above technical problems and to provide a motor control device capable of simplifying the configuration by handling a relatively small current. [0005] The present invention provides an inverter circuit.
3 that is driven to rotate based on a drive signal input from the road
Provided phase AC drive motor, capacitor and rotation speed detection device for detecting the rotational speed of the motor and outputs a pulse signal corresponding to the rotation of the motor, two pulse period of the pulse signal
Is determined by the time constant determined by the capacitance C1 and the resistance R1 of the
A predetermined voltage is applied to one end of the capacitor,
One end of the resistor is connected to the other end of the capacitor,
The other end is grounded and the output from the other end of the capacitor is
By comparing the pulse signals from the rotation speed detecting element,
Over the pulse period, the when the pulse signal is detected that is not output from the rotation speed detection device, the detection each rotational speed to output a signal it is determined that the locked state of the motor
And three processing circuit provided for each element, the three processing
Forced stop when no signal from circuit is input
An AND circuit for outputting a signal to the inverter circuit;
It is a motor control device having . According to the present invention, the number of revolutions of a three-phase AC drive motor that is rotationally driven based on an input control signal is provided in the motor, and a pulse signal corresponding to the rotation of the motor is provided. It is detected by the output rotation speed detecting element. The processing circuit detects whether or not a pulse signal is output from the rotation speed detecting element over a two-pulse cycle . Then, over two pulse period, when the pulse signal is detected that is not output from the rotation speed detection device, determines that the locked state of the motor. The AND circuit
No signal is input from any of the three processing circuits
Sometimes, a forced stop signal is output to the inverter circuit.
As a result, a relatively small signal current from the rotation speed detecting element is handled, and the configuration of the motor control device can be simplified. FIG. 1 is a block diagram showing a basic configuration of the present invention. In the following description, a three-phase AC drive motor
(Hereinafter, motor) will be described . The motor lock detection function in the motor control device 1 of the present invention is provided in the motor and includes three Hall elements 2 as examples corresponding to three-phase windings of the motor for detecting the number of rotations of the motor.
This is performed based on the signals from 3 and 4. Each Hall element 2,
The detection signals Hu, Hv, and Hw from 3, 4 are used as an example.
Each of the detection signals Hu and H is input to a logic element such as the D circuit 5.
If any one of v and Hw is not input to the AND circuit 5 for a predetermined period, it is determined that the motor is in a locked state, and a motor forced stop signal is output. FIG. 2 is a block diagram showing a configuration example of the motor control device 1 according to one embodiment of the present invention, and FIG. 3 is a time chart for explaining the operation of the motor control device 1. In this embodiment, a motor 6 is used. An inverter circuit 7 for outputting a drive signal for driving the motor 6 is connected to the motor 6. The motor 6 detects a change in the magnetic pole of each phase of the motor 6 and outputs a pulse signal corresponding to the change in the magnetic pole. The three Hall elements 2, 3,
4 are arranged. The detection signals Hu, Hv, Hw from each of the Hall elements 2, 3, 4 are respectively processed by processing circuits 8, 9,
10 is input. Each of the processing circuits 8, 9, 10 detects whether or not each of the detection signals Hu, Hv, Hw is input over a two-pulse cycle. The predetermined period is determined as a time constant determined by the capacitance C1 and the resistance R1 externally connected to each of the processing circuits 8 , 9 , 10. The output of each of the processing circuits 8, 9, 10 is AND
Input to the circuit 5. The output of the AND circuit 5 has three A's.
The signals are commonly input to the ND circuits 11, 12, and 13. Each AN
Each of the Hall elements 2, 3, 4 is provided in each of the D circuits 11, 12, and 13.
, The detection signals Hu, Hv, Hw are input. The outputs of the AND circuits 11, 12, and 13 are input to the inverter circuit 7. On the other hand, a speed command signal for causing the motor 6 to have a predetermined rotation speed is output from the signal source 14 and input to the collector of the transistor 16. The emitter of transistor 16 is illustratively connected to ground potential. The base of the transistor 16 has the AND circuit 5
Is output by the inverting circuit 15 to receive an inverted signal. As shown in FIGS. 3A and 3B, for example, if the detection signal Hu is output without any pulse loss, the output from each of the processing circuits 8, 9, and 10 is output. Is high level. Thereby, the AND circuit 5
Becomes high level, and each of the AND circuits 11, 12,
A signal in which the detection signals Hu, Hv, and Hw are modulated by the speed command signal is output to the inverter circuit 7 via 13. On the other hand, as shown in FIGS. 3 (3) and 4 (4), for example, when the detection signal Hu has one or more missing pulses, the output from the corresponding processing circuit 8 is at a low level. It becomes. As a result, the output of the AND circuit 5 goes low, and each of the AND circuits 11, 12, 13
Is shut off. Thereby, the motor 6 is forcibly stopped. As described above, in the present embodiment, the lock detection of the motor 6 is performed using the signals of small current values such as the detection signals Hu, Hv, and Hw from the Hall elements 2, 3, and 4. 6 can be simplified. As described above, according to the present invention, a relatively small signal current from the rotation speed detecting element is handled, and the configuration of the motor control device can be simplified.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a basic configuration of the present invention. FIG. 2 is a block diagram illustrating a configuration example of a motor control device 1 according to an embodiment of the present invention. FIG. 3 is a time chart for explaining the operation of the motor control device 1; [Description of References] 1 Motor control device 2, 3, 4 Hall element 5, 11, 12, 13 AND circuit 8, 9, 10 Processing circuit 6 Motor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02H 7/093 H02P 3/18 H02P 5/00 H02P 6/12

Claims (1)

(57) Claims 1. A three-phase AC drive motor that is driven to rotate based on a drive signal input from an inverter circuit, and outputs a pulse signal corresponding to the rotation of the motor. a rotation speed detection device for detecting the rotational speed of the motor, the capacity of 2 pulse period the capacitor of the pulse signal C1
And the time constant determined by the resistor R1
Apply a predetermined voltage to one end of the capacitor,
Connect one end of the resistor to one end and ground the other end of the resistor
The output from the other end of the capacitor and the rotation speed detection.
The pulse signal from the output element is compared , and when it is detected that the pulse signal is not output from the rotation speed detecting element over the two pulse periods , it is determined that the motor is in the locked state, and the signal is determined. setting said each rotational speed detecting device for outputting an
Three processed circuits, and none of the signals from the three processed circuits are input.
A for outputting a forced stop signal to the inverter circuit
A motor control device comprising: an ND circuit .