KR100835218B1 - an apparatus an a method for preventing a motor from a overheated state - Google Patents

Abstract

The present invention relates to a motor overheating prevention device and method.

According to the present invention, when the current or power input to the motor is greater than the motor drive specification and the motor drive time exceeds the allowable time, it is determined through the heat generation temperature of the motor to reduce the output of the motor or stop driving. Here, the present invention measures the exothermic temperature of the motor through an indirect method. That is, the current input to the motor is measured and converted into temperature. This converted temperature is compared with the temperature according to the motor drive rated value calculated programmatically and used for output control and stop control of the motor.

According to an embodiment of the present invention, the present invention has an effect of preventing the operation interruption and damage of the motor due to overheating by indirectly sensing the temperature of the motor that is difficult to measure the temperature.

Motor, heating temperature, integrator, temperature conversion, current

Description

An apparatus for preventing overheating of a motor and its method {an apparatus an a method for preventing a motor from a overheated state}

1 is a block diagram of a conventional motor overheat prevention device.

Figure 2 is a block diagram of another conventional motor overheat prevention device.

3 is a block diagram of a motor overheating prevention device according to an embodiment of the present invention.

4 is an operation flowchart of the motor overheating prevention device according to an embodiment of the present invention.

The present invention relates to a motor overheating prevention device and method, and more particularly, to a device and a method for preventing overheating of the motor by converting the amount of heat generated in the motor into a temperature value.

In general, when the load is applied to the motor, the operating temperature is increased. If the operating temperature of the motor is too high, the carbon brush, the commutator, and the support of the motor are worn, and, in severe cases, a winding short circuit due to damage to the insulation part occurs. .

In order to prevent this problem, the prior art as shown in Figures 1 and 2 was used.                         

1 is a block diagram of a conventional motor overheat prevention device. As shown in FIG. 1, the conventional motor overheat prevention device configures a temperature dependent resistance 16 and a voltage dividing resistor 17 in series, and sets a voltage therebetween in the Schmitt trigger threshold comparison unit 18. Determine whether the motor is overheated by comparing with the threshold. By this determination, the motor overheat prevention device judges that the motor is overheated if the measured voltage is higher than the Schmitt trigger threshold, and cuts off the shutoff device 13 to prevent overheating of the motor. Here, the temperature-dependent resistance is lowered as the temperature is higher, the voltage value input to the Schmitt trigger threshold comparison unit 18 is lowered. However, the prior art of FIG. 1 has a problem that it is difficult to detect the temperature rise of the rotor in reading the temperature around the motor 15 to prevent overheating of the motor.

2 is a block diagram of another conventional motor overheat prevention device. The motor overheat prevention device shown in FIG. 2 configures the analog circuit 29 based on the time-rated value of the motor, obtains the absolute value of the current flowing into the motor 26 through the absolute value circuit 28, and integrates the circuit. Time integration through the (29), the result is a method of controlling the breaker 22 through a comparison circuit. In the prior art of FIG. 2, since the temperature rise of the motor is determined by measuring the current using the current sensor 25, it is easy to install, but it is difficult to implement the time-current rated value of the motor as an accurate analog integrating circuit and reduce noise. There is a problem that may occur due to the error rate.

The present invention is to solve the conventional problems, and to indirectly measure the calorific value of the motor, and calculates the temperature of the motor from the measured calorific value information to prevent damage to the motor due to the increase in the motor temperature.

Motor overheating prevention device according to a feature of the present invention for achieving the above technical problem,

If the current inputted to the motor or the electric power is larger than the motor drive specification and the motor drive time exceeds the allowable time, it is judged by the heating temperature of the motor to reduce the output of the motor or stop driving. Here, the present invention measures the exothermic temperature of the motor through an indirect method. That is, the current input to the motor is measured and converted into temperature. This converted temperature is compared with the temperature according to the motor drive rated value calculated programmatically and used for output control and stop control of the motor.

Therefore, the motor overheating prevention apparatus according to the characteristics of the present invention for achieving the above technical problem,

A power output unit for supplying corresponding power to the motor according to the control signal;

A current measuring unit which senses a current input to the motor from the power output unit and measures the sensed current;

A temperature calculation unit converting the current sensed by the current measurement unit into a temperature in consideration of a motor driving time by repeatedly calculating a predetermined interrupt time;

A comparator comparing the temperature converted by the temperature calculator with a set temperature and outputting a result;

Set the allowable operating current for the motor and the time-current rated current as a percentage of the rated current of the motor, set the time-current rated time, and set the thermal time constant using the set operation, the rated current and time. And a controller for calculating an integrator, providing the integrator to the temperature calculator, and determining whether to drive the motor according to the output of the comparator.

A blocking unit driving according to a control signal of the controller to stop output of the power output unit; And

And a temperature display unit for driving the control signal of the controller to display the temperature information output from the temperature calculator so that the user can check the temperature information.

Motor overheating prevention method according to another feature of the present invention for achieving the above technical problem,

A first step of setting a value as a percentage of the rated current of the motor by receiving the allowable operating current, the current and time of the time-current rating before driving the motor;

A second step of calculating a thermal time constant using the set allowable operating current, current and time of a time-current rating;

A third step of calculating an integrator used for repetitive operation in an interrupt time period using the calculated thermal time constant;

Setting a heat generation temperature of the motor to “0” and applying a corresponding electric power to the motor to drive the motor;                     

Measuring a current applied to the motor and converting the measured current into an exothermic temperature of the motor using the integrator at intervals of the interrupt time;

A sixth step of comparing the converted exothermic temperature with a set temperature; And

In the comparison, when the heating temperature is higher than the set temperature, the motor is stopped, and when the heating temperature is lower than the set temperature, the heating temperature is displayed so that the user can check the speed control of the motor by the user. It includes 8 steps.

Hereinafter, a motor overheating prevention apparatus and a method thereof according to an embodiment of the present invention with reference to the accompanying drawings.

3 is a block diagram of a motor overheating prevention device according to an embodiment of the present invention.

As shown in Figure 3, the motor overheat prevention apparatus according to an embodiment of the present invention, the adjusting unit 100, the blocking unit 200, the power output unit 300, the current sensor 400, the motor 500, the sensor processing unit 600, a thermometer calculation unit 700, a comparison unit 800, and a temperature display unit 1000.

The adjusting unit 100 is operated by the user to generate a command signal for adjusting the output (rotational speed) of the motor and output the command signal to the control unit 900.

 The controller 900 determines the command signal output from the controller 100 to control the output power of the power output unit 300, and after the motor 500 is driven, through the output value of the comparator 800. When the heat generation temperature of the motor is monitored and it is determined that the heat generation amount of the motor exceeds the rated value, the output power of the power output unit 300 is controlled to reduce the output (speed) of the motor 500. In addition, the control unit 900 stops the motor 500 by driving the blocking unit 200 if the heat generation amount of the motor 500 exceeds the rated value.

Meanwhile, the control unit 900 receives the allowable operating current Iinv, the current Itx of the time-current rating and the time Tx before the motor is operated, and the allowable operating current Iinv and the current of the time-current rating. Set (Itx) as a percentage of the rated current of the motor. Then, the control unit 900 calculates the thermal time constant (τ) of the motor based on the allowable operating current (Iinv), the current (Itx) and the time (Tx) of the time-current rating, and calculates the integrator (A). do.

The power output unit 300 generates power corresponding to the control signal of the controller 900 and supplies the generated power to the electric motor 500.

The current sensor 400 is located between the output terminal of the power output unit 300 and the input terminal of the motor 500 to detect a current input to the motor 500 and supplies it to the current measuring unit 600. Here, the current sensor 400 is a CT (current transdecer).

The current measuring unit 600 receives the current sensed by the current sensor 400, calculates it, and delivers the calculated current to the temperature calculating unit 700. In this case, the current measuring unit 600 converts to a root mean square (RMS) current when the motor 500 is an AC motor, obtains an average current in units of 0.5 seconds, and calculates the load ratio as a percentage of the rated load. . On the other hand, the current measuring unit 600 serves to calculate the absolute value of the average current in units of 0.5 seconds when the electric motor is a direct current motor, and calculates it as a% load ratio compared to the rating.

 The temperature calculator 700 estimates the temperature generated by the motor 500 by converting the current input from the current measuring unit 600 into a temperature, and outputs the estimated temperature to the controller 900 and the comparator 700. .                     

The comparing unit 700 compares the temperature estimated by the temperature measuring unit 700 with the set temperature, and outputs the result to the control unit 900. Here, the set temperature is a temperature corresponding to the motor operation stop value.

The controller 900 receives the information on the motor temperature output from the temperature calculator 700, drives the temperature display unit 1000 to be displayed on the temperature display unit 1000, and outputs a comparison value output from the comparator 800. By judging, it is determined whether to drop the output of the power output unit 300 by estimating the current temperature of the motor or to stop the motor 500 by driving the breaker 200.

Hereinafter, the operation of the motor overheat prevention apparatus according to an embodiment of the present invention with reference to the accompanying FIG.

4 is an operation flowchart of the motor overheating prevention device according to an embodiment of the present invention.

Before driving the motor 500, the driver controls the control unit (100) to adjust the allowable driving current (Iinv), time-current rated current (Itx) and time (Tx) through the adjusting unit (100) through the driving specification of the motor (500). In step 900, it is input.

Then, the control unit 900 stores the allowable operating current Iinv, the current Itx and the time Tx of the time-current rating. At this time, the allowable operating current (Iinv) and the current (Itx) of the time-current rating is set to a value as a percentage of the rated current of the motor 500 (S200).

As described above, it is for convenience of calculation that the allowable operating current Iinv and the current Itx of the time-current rating are the ratio of the rated current to the percentage ratio (current / rating * 100) and the time Tx is the actual time. . Therefore, it is irrelevant even if all of said variables (Iinv, Itx) are made into real current.

Then, the control unit 900 substitutes the set allowable operating current Iinv, the current Itx of the time-current rating and the time Tx into the following Equation 1, and the thermal time constant τ of the motor 500. Calculate (S300).

The controller 900 calculates the integrator A used when the thermal time constant τ is obtained through Equation 1 and then iteratively computes at a 0.5 second cycle (S400).

Here, 0.5 is an iteration operation period, that is, an interrupt cycle time.

The controller 900 stores the integrator A calculated above and an iterative operation cycle, that is, an interrupt cycle, and provides the temperature to the temperature calculator 700 when the temperature calculator 700 is driven.

After calculating the integrator A, the controller 900 sets the exothermic temperature, that is, the calculated temperature value Tm, of the electric motor 500 to "Tm = 0" (S500).

In the state set as described above, the driver operates the adjusting unit 100 to set the output of the electric motor 500 so that several products can be produced per hour, and the adjusting unit 100 generates a corresponding command signal accordingly. To the control unit 900.

The controller 900 transmits a signal for controlling the output of the power output unit 300 corresponding to the input command signal to the power output unit 300 through the blocking unit 200. Then, the power output unit 300 outputs a current for the corresponding power in accordance with the control signal (S600).

The output current of the power output unit 300 is input to the motor 500 to drive the motor 500, the current sensor 400 detects the current input to the motor 500 to provide to the current measuring unit 600 do. The current measuring unit 600 measures the input current to determine the current value and provides the determined current value to the temperature calculator 700.

The temperature calculator 700 receives the integrator A and the interrupt time (= 0.5) from the controller 900, and receives the current input to the motor 500 provided by the current measuring unit 600, thereby providing 0.5 seconds. The heat generation temperature of the motor is calculated through Equation 3 as an interrupt time period (S700).

Where I is the actual current input to the motor.

Equation 3 mathematically indicates that when the motor 500 is continuously driven, the temperature of the motor 500 gradually increases, and the temperature of the motor 500 increases according to the current value input to the motor.

The temperature calculator 700 estimates the exothermic temperature Tm in the current electric motor 500 through Equation 3, and compares the estimated present exothermic temperature Tm to the comparator 800 and the controller 900. Output

The comparator 800 compares the exothermic temperature Tm input from the temperature calculator 700 with the set stop temperature Trip, and determines whether the exothermic temperature Tm is lower than the stop temperature Trip or the exothermic temperature. A signal indicating whether Tm is higher than the stop temperature Trip is output to the controller 900 (S800).

Here, the stop temperature Trip is a temperature that can be tolerated by the motor 500, and when the temperature is higher than this temperature, damage may occur to the motor 500.

Therefore, when the value input from the comparator 800 is a value that the heat generation temperature Tm is higher than the stop temperature Trip, the controller 900 controls the breaker 200 to stop driving of the motor 500. (S900).

However, if the value input from the comparator 800 is a value that the heat generation temperature Tm is lower than the stop temperature Trip, the control unit 900 generates heat from the comparator 800. If the temperature Tm is lower than the stop temperature Trip, the temperature display unit 1000 may provide the heat generation temperature information input from the temperature calculator 700 to the temperature display unit 1000 to display the heat generation temperature ( S1000).

When the heat generating temperature of the electric motor 500 is displayed on the temperature display part 1000, the user may generate a command signal for reducing the output of the motor 500 by checking the displayed heat generating temperature by manipulating the adjusting part 100. Thus, the power output unit 300 drops the current input to the motor 500 so that the driving speed of the motor is slowed or accelerated.                     

Thus, the motor 500 is prevented from being overheated because the output falls or stops.

In the above description with reference to FIG. 3, the temperature calculator 700 and the comparator 800 are separated from the controller 900. However, those skilled in the art will appreciate that the temperature calculator 700 and the comparator 800 are included in the controller 900. It is possible to design to include.

The technical spirit of the present invention has been described above with reference to the accompanying drawings, but this is by way of example only and not intended to limit the present invention. In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

According to the above embodiment, the present invention has an effect of indirectly detecting the temperature of the motor that is difficult to measure the temperature during operation to prevent operation interruption and damage to the motor due to overheating.

Claims (15)

A power output unit for supplying corresponding power to the motor according to the control signal; A current measuring unit configured to sense a current input to the electric motor from the power output unit and measure the sensed current; A temperature calculation unit converting the current sensed by the current measurement unit into a temperature in consideration of a motor driving time by repeatedly calculating a predetermined interrupt time; A comparator for comparing the temperature converted by the temperature calculator with a preset temperature and outputting a result; The allowable operating current for the motor, time-current rated current and time-current rated time are set, and a thermal time constant and an integrator are calculated using the set operation, the rated current and time, and the integrator calculates the temperature. A control unit provided to a calculation unit and determining whether to drive the motor according to the output of the comparison unit; A blocking unit driving according to a control signal of the controller to stop output of the power output unit; And And a temperature display unit which is driven according to a control signal of the controller to display the temperature information output from the temperature calculator for the user to check. In claim 1, The allowable operating current and time-current rated current, The motor overheat prevention device, characterized in that it is set to the ratio of the rated current of the motor. In claim 2, The thermal time constant (τ) and the integrator (A) using the following equation, the motor overheat prevention device.

In the above, Iinv: allowable operating current, Itx: current of time-current rating Tx: time of time-current rating, τ: thermal time constant of the motor A: Integrator used when iterating. In claim 1, The current measuring unit, And a current sensor positioned between the output end of the power output unit and the motor, the current sensor sensing a current input to the motor, and a current meter measuring the current sensed by the current sensor. In claim 4, The current sensor is a CT (current transducer) characterized in that the motor overheat prevention device. In claim 4, The current meter, In the case where the motor is an AC motor, the motor is overheated by converting a current sensed from the current sensor into an RMS current, obtaining an average current in units of the interrupt time, and calculating the load ratio as a percentage of the rated current. Prevention device. In claim 4, The current meter, If the motor is a DC motor, the motor overheating prevention device, characterized in that for calculating the absolute value of the average current in the unit of the interrupt time, the current sensed from the current sensor, and calculates as a% load ratio to the rated. In claim 1, And the interrupt time is 0.5 seconds. In claim 1, The temperature calculation unit, The motor overheat prevention device, characterized in that for calculating the current temperature of the motor through the following equation received from the integrator calculated by the controller.

In the above, Tm: current exothermic temperature (calculated temperature) of the motor, A: integrator I: current input to electric motor A first step of setting allowable operating current, time-current rated current and time before the motor is driven; A second step of calculating a thermal time constant using the set allowable operating current, current and time of a time-current rating; A third step of calculating an integrator used for repetitive operation in an interrupt time period using the calculated thermal time constant; Setting a heat generation temperature of the motor to “0” and applying a corresponding electric power to the motor to drive the motor; Measuring a current applied to the motor and converting the measured current into an exothermic temperature of the motor using the integrator at intervals of the interrupt time; A sixth step of comparing the converted exothermic temperature with a set temperature; And In the comparison, when the heating temperature is higher than the set temperature, the motor is stopped, and when the heating temperature is lower than the set temperature, the heating temperature is displayed so that the user can check the speed of the motor by the user. The motor overheating prevention method comprising the eighth step. In claim 10, The allowable operating current and time-current rated current, The motor overheating prevention method, characterized in that it is set to the ratio of the rated current of the motor. In claim 11, The second step, The thermal time constant (τ) is a motor overheating prevention method, characterized in that using the following equation.

In the above, Iinv: allowable operating current, Itx: current of time-current rating Tx: The time of the time-current rating. In claim 10, The third step, The integrator uses the following equation, the motor overheating prevention method.

τ: Thermal time constant of the motor, A: Integrator used for repetitive calculation. In claim 10, The fifth step, Converting a current inputted into the motor into an RMS current when the motor is an AC motor, calculating an average current in units of the interrupt time, and calculating the load ratio as a percentage of the rated load, and using the following equation. Electric motor overheating prevention method.

In the above, Tm: current exothermic temperature (calculated temperature) of the motor, A: integrator I: current input to electric motor In claim 10, The fifth step, If the electric motor is a direct current motor, the step of calculating the absolute value of the average current in the unit of the interrupt time to the current input to the motor, and performing the role of calculating the percent load ratio to the rating, and using the following equation How to prevent the motor overheating.

In the above, Tm: current exothermic temperature (calculated temperature) of the motor, A: integrator I: current input to electric motor

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