JPH0340790A - Protecting device for motor driver - Google Patents

Abstract

PURPOSE:To suitably protect a motor by detecting a power source voltage, obtaining a voltage level to be converted from the detected voltage level, and continuing the operation of the motor even if the power source voltage level is lowered when the voltage level to be converted is a control output voltage level or higher. CONSTITUTION:A voltage level calculator 10 receives a detected power source voltage Vs, obtains a voltage level to be converted by a motor driver 2 with the voltage Vs level, and sends the voltage level to be converted to a comparator 11. The comparator 11 receives a control signal S from a control circuit 4, obtains a control output voltage level in the driver 2, and compares the control output level with the voltage level to be converted from the calculator 10. When the voltage level to be converted is higher than the control output level, even if the voltage Vs is lowered, the operation of a motor 5 is continued.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a protection device for a motor drive device.

(Prior Art) FIG. 3 is a block diagram of such a protection device. Power supply 1 electric F
A voltage v5 is supplied to the motor drive device 2. or,
A control circuit 4 to which a rotation speed setting device 3 is connected is provided, and this control circuit 4 generates a control signal for output voltage (control output voltage) of the motor drive device 2 according to the rotation speed set by the rotation speed setting device 3. Output S. Thereby, the motor drive device 2 receives the control signal S, converts the power supply voltage V5 into a voltage level corresponding to the rotation speed, and supplies the voltage level to the motor 5. Thus, the electric motor 5 rotates. On the other hand, a power supply voltage Vs is detected by a transformer 6 connected to the power supply 1, and a voltage Ve having a level corresponding to this power supply voltage Vs is sent to a comparator 7. A detection setter 8 for setting a voltage level for detecting a drop in the power supply voltage vs is connected to the comparator 7, and a drop detection voltage Vf set by the detection setter 8 is sent. Note that, as shown in FIG. 4, the drop detection voltage Vf is set to a level 10% lower than the rated input voltage Va, regardless of the rotational speed of the electric motor 5. Thereby, the comparator 7 compares each level of the voltage Ve and the drop detection voltage Vf, and sends an undervoltage signal to the undervoltage protection sequence circuit 9 when the voltage Ve becomes lower than the drop detection voltage Vf. As a result, the undervoltage protection sequence circuit 9 that received the undervoltage signal issues a stop command to the control circuit 4, and the control circuit 4 that received this stop command issues a control signal to make the output voltage of the motor drive device 2 zero. Do S. Thus, the output voltage of the motor drive device 2 becomes zero and the rotation of the motor 5 stops.

However, in the protection device configured as above, the drop detection voltage Vf is set to a constant value regardless of the rotational speed of the electric motor 5. Therefore, for example, when the electric motor 5 is operated at a slow rotational speed, the low power supply voltage vs. Although the electric motor 5 can be operated even in this case, there is a problem in that the electric motor 5 is stopped because it is determined that the power supply voltage V5 is insufficient.

(Problem to be Solved by the Invention) As described above, since the drop detection voltage Vf is set to a constant value regardless of the rotational speed of the electric motor 5, the problem is that the electric motor 5 stops even if it can continue operating. There is.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a protection device for a motor drive device that can detect a drop in power supply voltage depending on the operating state of the motor and provide appropriate protection depending on the operating state of the motor.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides an electric motor that converts a power supply voltage into a voltage level according to the number of revolutions of an electric motor using a motor drive device, and that stops the electric motor when the power supply voltage level drops below a predetermined voltage level. In a protection device for a drive device, a voltage level calculation means detects a power supply voltage level and calculates a voltage level convertible by the motor drive device from this power supply voltage level, and a convertible voltage level determined by the voltage level calculation means. and a control output voltage level commanded to a motor drive device, and an operation control means that causes the motor to continue operating if the convertible voltage level is equal to or higher than the control output voltage level. This is a protection device for electric motor drive equipment.

(Function) By providing such means, the motor drive device converts the power supply voltage to a voltage level corresponding to the rotation speed of the motor and stops the motor when the power supply voltage level drops below a predetermined voltage level. In the protection device, the power supply voltage is detected by the voltage level calculation means, a voltage level that can be converted by the motor drive device is determined from the detected power supply voltage level, and the operation control means detects the voltage level that can be converted by the motor drive device. If the control output voltage level is higher than the control output voltage level commanded to the drive device, the motor continues to operate even if the power supply voltage level decreases.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. Note that the same parts as in FIG. 3 are given the same reference numerals, and detailed explanation thereof will be omitted.

FIG. 1 is a block diagram of a protection device for a motor drive device. In the figure, A is a voltage level calculation means, and this voltage level calculation means A has a function of detecting a power supply voltage level and determining a voltage level convertible by the motor drive device 2 from this power supply voltage level. . Specifically, it is composed of a transformer 6 and a voltage level calculation circuit 10 connected to the secondary side of the transformer 6. The voltage level calculation circuit 10 calculates the power supply voltage V of the power supply 1 through the transformer 6.

It has a function of detecting the R voltage V and determining the voltage level that can be converted by the motor drive device 2. Further, B is an operation control means, and this means B compares the convertible voltage level obtained by the voltage level calculation means A with the control output voltage level commanded to the motor drive device 2 to determine the convertible voltage. If the level is equal to or higher than the control output voltage level, it has the function of causing the electric motor 5 to continue operating.

Specifically, it is composed of a comparator 11 and an undervoltage protection sequence circuit 9. The comparator 11 receives the convertible voltage level from the voltage level calculation circuit 10 and receives the control signal S from the control circuit 4 to determine the control output voltage level of the motor drive device 2, and compares these convertible voltage levels with the control signal S. If the convertible voltage level is higher than the control output voltage level by comparing the output voltage level, that is, if the convertible voltage level ≧ the control output voltage level, the motor 5 is activated without operating the undervoltage protection sequence circuit 9. continues operation, and sends an undervoltage signal to the undervoltage protection sequence circuit 9 if the voltage level is convertible or the control output voltage level.

Next, the operation of the apparatus configured as described above will be explained.

A power supply voltage V is supplied to the motor drive device 2. Further, the control circuit 4 outputs a control signal S of the output voltage of the motor drive device 2 according to the rotation speed of the electric motor 5 set in the rotation speed setting device 3. As a result, the motor drive device 2 receives the control signal S, converts the power supply voltage V5 into a voltage according to the rotation speed, and supplies the voltage to the motor 51. Thus, the electric motor 5 rotates.

On the other hand, the transformer 6 generates a voltage Ve according to the power supply voltage vs.
is sent to the voltage level calculation circuit 10.

The voltage level calculation circuit 10 receives the power supply voltage V and determines a voltage level that can be converted by the motor drive device 2 based on the power supply voltage (2). Then, the voltage level calculation circuit 10 sends the convertible voltage level to the comparator 11. On the other hand, a control signal S from the control circuit 4 is input to this comparator 11 . However, this comparator 11 receives the control signal S from the control circuit 4, determines the control output voltage level at the motor drive device 2, and compares this control output voltage level with the convertible voltage level from the voltage level calculation circuit 10. Compare. By the way, the control output voltage level determined by the control signal S from the control circuit 4 is as shown in FIG.
is proportional to the rotation speed. ,, Therefore, the control output voltage level is set as the voltage for detecting a drop in the voltage xi voltage V5 by the comparator 1.
1, the comparator 11 outputs the power supply voltage V at a control output voltage level corresponding to the rotational speed of the motor 11.
A decrease in s will be detected. Therefore, the comparator 11 compares the convertible voltage level and the control output voltage level, and if the convertible voltage level is larger than the control output voltage level, that is, if the convertible voltage level ≧ the control output voltage level. ,
Even if the power supply voltage vs decreases, the operation of the electric motor 5 is continued.

Further, as a result of the comparison of the respective voltage values, if the voltage level is convertible or the control output voltage level, the comparator 11 sends an undervoltage signal to the undervoltage protection sequence circuit 9. As a result, the undervoltage protection sequence circuit 9 that received the undervoltage signal issues a stop command to the control circuit 4, and the control circuit 4 that received this stop command issues a control signal to make the output voltage of the motor drive device 2 zero. Do S. Thus, the output voltage of the motor drive device 2 becomes zero and the rotation of the motor 5 stops.

In this way, in the above embodiment, the convertible voltage level in the motor drive device 2 is determined from the power supply voltage VS, and if this convertible voltage level is equal to or higher than the control output voltage level commanded to the motor drive device 2, Since the electric motor 5 continues to operate, a decrease in the power supply voltage V can be detected by changing the voltage level for detecting a decrease in the voltage 111X (5) in accordance with the operating state of the electric motor 5, that is, the rotational speed. Therefore, even when the rotational speed of the electric motor 5 is slow and high voltage is not required, for example, the electric motor 5 can continue to operate without being stopped. As a result, the electric motor 5 can be appropriately protected depending on the operating state, and the electric motor 5 can be driven with high continuous operation ability.

Note that the present invention is not limited to the above-mentioned embodiment, and may be modified without departing from the spirit thereof. For example, when the motor drive device 2 supplies a DC voltage to a DC motor using a rectifier circuit with a 6-phase Gretz connection, the voltage level calculation circuit 1o calculates the voltage value V that can be converted by the motor drive device 2.
dcrAax to Vdcgax -1,35V a 1
Determined by 1 cos a. Here, α1 is a control limit value determined by the circuit configuration.

[Effects of the Invention] According to the present invention, it is possible to provide a protection device for a motor drive device that can detect a drop in electric power Fi and voltage depending on the operating state of the motor and can provide appropriate protection depending on the operating state of the motor.

[Brief explanation of drawings]

1 and 2 are diagrams for explaining one embodiment of a protection device for a motor drive device according to the present invention, in which FIG. 1 is a configuration diagram and FIG. 2 is a diagram showing a control output voltage level. , 3rd
FIG. 4 is a diagram for explaining the prior art. A... Voltage level calculation means, B... Operation control means,
DESCRIPTION OF SYMBOLS 1... Power supply, 2... Electric motor drive device, 3... Rotation speed setting device, 4... Control circuit, 5... Electric motor, 6...
・Transformer, 9... Undervoltage protection sequence circuit, 10
... Voltage level calculation circuit, 11... Comparator.

Claims (1)

[Claims] In a protection device for a motor drive device, which converts a power supply voltage into a voltage level according to the rotation speed of the motor by a motor drive device and stops the motor when the power supply voltage level drops below a predetermined voltage level, the power supply voltage level voltage level calculation means for detecting the power supply voltage level and calculating a voltage level convertible by the motor driving device from the power supply voltage level; and control for instructing the convertible voltage level determined by the voltage level calculation means and the motor driving device. A protection device for an electric motor drive device, comprising: an operation control means that compares the convertible voltage level with an output voltage level and causes the electric motor to continue operating if the convertible voltage level is equal to or higher than the control output voltage level.