JP2007314181A - Reverse start determination device of electric blower - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reverse start determination device of an electric blower capable of detecting a reverse start by detecting the conducting current of the electric blower. <P>SOLUTION: The reverse start determination device of the electric blower, a reverse start determination circuit 16 determines the reverse start of the electric blower after the conducting current for the electric blower 1 monitored by a current detector 11 runs, and before the first reference time t1 is elapsed, and the conducting current is lower than the predetermined value. In addition, when the determination output of the reverse start is continuously output for the second reference time t2 or longer. An improper determination preventive circuit 17 performs the final determination of the reverse start, and outputs the final determination from a flip-flop 18. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a reverse rotation start determination device for an electric blower that detects reverse rotation start of an electric blower that cools an electric vehicle control device.

  In power converters such as converters and inverters used in electric vehicle control systems, for power conversion from single-phase AC to DC and DC to three-phase AC, for power such as gate turn-on thyristors (GTO thyristors) and high-speed diodes A semiconductor is used. Since these elements generate losses at the time of flow, switching at turn-on, and turn-off, a forced ventilation cooling method using an electric blower is generally employed using a condenser.

  When a single-phase AC motor is used as an electric blower drive motor for driving the electric blower, the power is turned on when a reverse force is forcibly applied to the electric blower by external ventilation or the like when no power is supplied. If the operation of the power conversion device is continued as it is, there is a possibility that it will sometimes reversely start, and the necessary cooling air volume will not be obtained, and the temperature will rise and the operation will be stopped.

  Further, normally, the electric blower is provided with a filter in order to prevent dust from entering the cooling system. This filter is cleaned at regular intervals, but if the filter becomes clogged with dust, the airflow of the electric blower will decrease, and the cooling airflow required for the condenser will not be obtained. Similarly, the temperature of the power conversion element is increased, and the operation of the power conversion device is stopped.

  Therefore, conventionally, a configuration shown in FIG. 4 has been adopted as a protective device for an electric blower for preventing operation stop of the power converter. This conventional electric blower protection device is installed in a pressure switch (PS) 3 in a cooling wind tunnel 2 in order to detect reverse rotation of the electric blower 1. The conventional electric blower protection device of FIG. 4 includes a slow motion element (TD1) 4 for limiting the detection of the reverse rotation of the electric blower 1 only when the electric blower 1 is started, and the detection of the reverse rotation of the electric blower 1. Slow motion element (TD2) 5, negation logic circuit (NOT1) 6, negation logic circuit (NOT2) 7, AND circuit (AND) 8, flip-flop 9 for not performing immediately after startup when the energization current is not settled It is constituted by.

  In this conventional electric blower protection device, when the electric blower 1 is turned on, the slow motion element (TD1) 4 starts to count the slow motion time t1, and the negative logic circuit (NOT1) until the slow motion time t1 elapses. ) “0” is output to 6, and the negative logic circuit (NOT 1) 6 continuously outputs the output logic “1”. Further, since the electric blower 1 is reversely activated after the power is turned on, the pressure in the cooling wind tunnel 2 does not increase, and the output logic of the pressure switch 3 becomes “1”. Therefore, both inputs of the AND circuit (AND) 8 are “1”, and the output logic is “1”. The output of the AND circuit 8 is input to the slow motion element (TD2) 5, and when the input logic “1” continues for the slow motion time t2 or longer, the output logic “1” is output to the flip-flop 7; The flip-flop 7 outputs a failure detection signal, stops the power conversion device, and opens the power supply of the electric blower 1. Further, by releasing the power supply of the electric blower 1, the output logic of the negative logic circuit (NOT2) 7 becomes “1”, and the flip-flop 7 is reset.

  However, in such a conventional electric blower protection device, the reverse activation of the electric blower 1 is detected by the pressure switch 3, so adjustment and maintenance of the pressure switch 3 are necessary, and an engineer is burdened with labor. There was such a problem. Further, when the air volume decreases due to clogging of the filter, the static pressure in the wind tunnel 2 increases due to the characteristics of the electric blower. Therefore, the pressure switch 3 that detects a decrease in atmospheric pressure detects the decrease in the air volume due to clogging of the filter. There was also a problem that could not be.

  By the way, the starting current of the electric blower increases rapidly until reaching a current value of 5A at a rated voltage, for example, a rated voltage of 440V. However, in the case of reverse rotation start-up, the start-up current does not change significantly as shown by curve A in FIG. Therefore, it is possible to monitor the current change within a short period immediately after the power is turned on, and when the current reference value set in advance is not exceeded, it is determined that the reverse rotation is started and the protection operation can be performed. Further, when this current comparison is performed after the energization current is settled, the reverse rotation start can be detected more accurately.

  Further, when the filter of the electric blower is clogged, the air flow of the electric blower decreases in the direction of a → b and the energization current is also the curve shown in FIG. As indicated by i-Q, the value changes to a value lower than normal (in the direction of c → d). Therefore, if the energization current after the power is set after power-on at normal startup becomes lower than a certain reference value. This can be regarded as a decrease in the air volume due to filter clogging.

  The present invention has been invented based on such technical considerations, and monitors the energization current of the electric blower, detects and outputs the reverse rotation of the electric blower according to the current behavior immediately after turning on the power, and performs maintenance. An object of the present invention is to provide a reverse rotation start determination device for an electric blower that can reduce the burden on an engineer required for adjustment.

  According to a first aspect of the present invention, there is provided a reverse start determination device for an electric blower comprising: current monitoring means for monitoring the behavior of an energization current from an AC power supply to the electric blower; and the energization current monitored by the current monitoring means is after the AC power supply is turned on. And a reverse rotation start determination means for determining and outputting the reverse rotation start of the electric blower when the preset reference time has elapsed and the current is lower than a predetermined value.

  According to a second aspect of the present invention, there is provided a reverse rotation start determination device for an electric blower comprising: current monitoring means for monitoring the behavior of an energization current from an AC power supply to the electric blower; and the energization current monitored by the current monitoring means is after the AC power is turned on. A reverse rotation start determination means for determining and outputting reverse rotation start of the electric blower when the preset first reference time has elapsed and the current is lower than a predetermined value; and the reverse rotation start determination means Is provided with erroneous determination preventing means for outputting the final determination of the reverse rotation start when the reverse rotation start determination output is continuously output for a preset second reference time or more.

  According to a third aspect of the present invention, in the reverse rotation start determination device for an electric blower according to the first or second aspect, voltage monitoring means for monitoring a voltage behavior of an AC power supply with respect to the electric blower, and the conduction current monitored by the current monitoring means Current correction means for correcting the fluctuation based on the voltage behavior monitored by the voltage monitoring means and giving the fluctuation to the reverse rotation start determination means.

  In the reverse rotation start determination device for an electric blower according to the first aspect of the invention, when the energization current to the electric blower monitored by the current monitoring means is lower than a predetermined value before the reference time elapses after the power is turned on. Since the reverse rotation start determination means determines and outputs the reverse rotation start of the electric blower, adjustment and maintenance like a wind pressure sensor are required as in the case where the reverse rotation start is detected by a decrease in the wind pressure of the wind tunnel as in the past. No parts are required, and the labor load of engineers can be reduced accordingly.

  In the reverse rotation start determination device for the electric blower according to the second aspect of the present invention, the energization current to the electric blower monitored by the current monitoring means is lower than a predetermined value before the first reference time elapses after the power is turned on. In some cases, the reverse rotation start determination means determines the reverse rotation start of the electric blower, and when the reverse rotation start determination output is continuously output for the second reference time or longer, the erroneous determination prevention means Since the final judgment is output, immediately after turning on the electric blower, waiting for the reverse rotation start determination until the energization current has settled, preventing erroneous determination of reverse rotation start due to a temporary current drop. Reliability can be increased.

  In the reverse rotation start determination device for the electric blower of the invention of claim 3, when the energization current of the electric blower is also reduced due to the decrease in the power supply voltage, the detection value of the energization current is corrected and based on the corrected detection value of the energization current Therefore, when the energization current decreases due to a drop in the power supply voltage, it can be distinguished from the case of reverse rotation, and only reverse rotation can be detected accurately, improving the reliability of reverse rotation detection. Can do.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the configuration of a reverse rotation start determination device for an electric blower according to a first embodiment of the present invention. The reverse rotation start determination device for an electric blower according to the first embodiment includes an electric current detector 11 that detects an energization current of a single-phase AC power source for a drive electric motor (not shown) of the electric blower 1, A smoothing circuit 12 for smoothing the detection signal, and a comparison circuit (1) 13 for comparing the current value output from the smoothing circuit 12 with a reverse current set value SET1 obtained in advance from the current characteristics of the electric blower are provided.

  The reverse rotation start determination device for an electric blower also includes a slow motion element (TD1) 14 that outputs an ON signal with a delay of time t1 when the electric blower is turned on, and a negative logic circuit for the output of the slow motion element 14 (NOT (1)) 15, logical product circuit (AND (1)) 16 having the output of comparison circuit (1) 13 and the output of negative logic circuit 15 as inputs, and the output logical value of this logical product circuit 16 is constant. A slow motion element (TD2) 17 that outputs an output logical value when it continues for a time t2, and a flip-flop 18 that operates by outputting “1” of the slow motion element 17 and outputs a fault signal. Yes. Further, a negative logic circuit (NOT (2)) 19 for providing a reset signal to the flip-flop 18 when the power is released for resetting the flip-flop 18 is provided.

  The slow motion element (TD1) 14 is provided to limit the reverse rotation detection immediately after the power is turned on because the reverse rotation of the electric blower 1 occurs only when the power is turned on. If t1 has elapsed, even if the motor current decreases, the reverse rotation start determination device does not recognize the reverse rotation detection. The slow motion element (TD2) 17 is a time element provided to prevent reverse rotation detection immediately after the electric blower is turned on and until the energization current is settled.

  Next, the operation of the reverse rotation start determination device for an electric blower according to the first embodiment having the above-described configuration will be described. Immediately after the electric blower 1 is turned on, until the time t1 elapses, the input logic value of the negative logic circuit (NOT (1)) 15 is "0" by the slow motion element (TD1) 14, and therefore this negative logic The output logic value of the circuit 15 continues to be “1” during the time t1, and this becomes one input of the AND circuit (AND (1)) 16.

  Further, when the power is turned on, the current flowing through the electric blower 1 is detected by the current detector 11, and the current detection value output through the smoothing circuit 12 is input to the comparison circuit (1) 13, where the reverse current set value SET1 is set. When the comparison is made and reverse activation has occurred and the detected current value is lower, the output logic value “1” is output from the comparison circuit (1) 13, and this is the AND circuit (AND (1)) 16. As the other input.

  The AND circuit (AND (1)) 16 is “1” when both the input from the comparison circuit (1) 13 and the input from the negative logic solution path (NOT (1)) 15 are “1”. Before the time t1 immediately after the elapse of time and when the energization current of the electric blower 1 is lower than the reverse activation current set value SET1, the logic value “1” is continuously output. When the output “1” of the AND circuit (AND (1)) 16 continues for a time exceeding the set time t2 of the slow motion element (TD2) 17, the output logical value for the flip-flop 18 becomes “1”. 18 outputs a reverse start failure signal.

  The failure signal due to the reverse activation is given to a power converter (not shown), and a protection operation for opening the power supply is executed. Note that the failure signal output of the flip-flop 18 is reset when the output logic of the negative logic circuit (NOT (2)) 19 becomes “1” due to the power release.

  Thus, in the reverse rotation start determination device for the electric blower according to the first embodiment of the present invention, the energization current to the electric blower 1 is monitored, and the time defined by the slow motion element (TD1) 14 after the power is turned on. Before elapse of t1 and when the current is lower than the reverse rotation current set value SET1, it is determined that the electric blower is reversely activated, and the reverse rotation activation determination output is defined by the slow motion element (TD2) 17. By outputting a final determination of reverse rotation starting from the flip-flop 18 when the energization current continues for more than the settling time t2, receiving the final determination output of reverse rotation starting, stopping the power converter, and opening the power supply of the electric blower The protection operation at the time of reverse rotation is performed.

  In the first embodiment described above, the slow motion element (TD2) 17 for preventing reverse rotation detection immediately after the power is turned on until the energization current is set is not useful for preventing malfunction. However, this is not always necessary, and can be omitted if it is necessary to reduce costs or simplify the circuit configuration.

  Next, a reverse rotation start determination device for an electric blower according to a second embodiment of the present invention will be described with reference to FIG. The second embodiment is characterized by a voltage detector 20 for the single-phase AC power supply of the electric blower 1 in addition to the reverse rotation start determination device for the electric blower of the first embodiment shown in FIG. A divider 21 that divides the voltage value A detected by the voltage detector 20 by the power supply rated voltage value B, an output of the divider 21 is multiplied by a current detection value output by the smoothing circuit 12, and the result is compared. (1) A multiplier 22 for outputting to 13 is additionally provided. The other constituent elements are the same as those in the first embodiment, and the same parts are denoted by the same reference numerals.

  In the reverse rotation start determination device for an electric blower according to the second embodiment, the divider 21 calculates the ratio between the power supply voltage value A of the electric blower 1 detected by the voltage detector 20 and the rated voltage value B of the power supply voltage. Then, the multiplier 22 multiplies the ratio B / A by the detected current value of the electric blower 1 to correct the detected current value. That is, as shown in FIG. 5, the voltage-current characteristics of the electric blower 1 decrease when the voltage V increases (curve A1) and conversely when the voltage V decreases. The current value i increases (curve A2). Therefore, the actual current value i is corrected by B / A (i × B / A) and converted to the rated current value.

  Then, the fluctuation of the power supply current after the correction is monitored, and in the same way as in the first embodiment, after the power is turned on, before the time t1 defined by the slow motion time element (TD1) 14 elapses, and the reverse current When the current is lower than the set value SET1, it is determined that the electric blower 1 is reversely activated, and further, the reverse rotation activation determination output continues for a settling time t2 of the energization current defined by the slow motion element (TD2) 17. Since the final determination of the reverse rotation start is output from the flip-flop 18, the power conversion device is stopped in response to the final determination output of the reverse rotation start, and the protection operation at the time of the reverse rotation start is performed by opening the power supply of the electric blower 1. is there.

  As a result, according to the reverse rotation start determination device for an electric blower of the second embodiment, when the actual current value changes due to fluctuations in the power supply voltage of the electric blower 1, particularly when the actual current value decreases due to an increase in voltage. In addition, it is possible to prevent erroneous detection of reverse rotation and to accurately detect reverse rotation.

  Next, a reverse rotation start determination and a collision determination device for an electric blower according to a third embodiment of the present invention will be described with reference to FIG. The reverse rotation start determination and the collision determination device of the electric blower of the third embodiment is further reduced in the air volume due to the clogging of the filter of the electric blower 1 compared to the second embodiment shown in FIG. The detection circuit 30 is added. In addition, the same code | symbol is attached | subjected to the component which is common in 2nd Embodiment shown in FIG. 2, and the detailed description is abbreviate | omitted.

  The air flow rate drop detection circuit 30 is a comparison circuit (2) 31 that compares the output (1) of the multiplier 22 in the energization current detection system of the second embodiment with the current set value SET2, and the electric blower 1 is turned on. A logical product circuit (AND (2)) 32 for calculating a logical product of the output (2) of the slow motion element (TD1) 14 at time t1 and the output of the comparison circuit (2) 31 with respect to the signal, and the logical product circuit (AND (2)) 32 is composed of a slow motion element (TD3) 33 at time t3 with respect to the output logical value of 32, and an alarm output is output from the slow motion element (TD3) 33 when an air flow rate drop is detected during normal startup. Is what you do. The current set value SET2 is set in advance to a value commensurate with the energization current value when the air volume is reduced due to clogging of the filter obtained from the characteristics of the single-phase AC motor of the electric blower 1. That is, it is set to a value slightly lower than the point d of the iQ curve in FIG.

  Hereinafter, the operation of the reverse rotation start determination and the collision determination device of the electric blower according to the third embodiment will be described. When the reverse rotation of the electric blower 1 occurs, the operation is exactly the same as in the second embodiment, and a failure signal is output from the flip-flop 18 to open the electric blower power supply.

  And at normal startup, it operates as follows. During the time t1 immediately after the power is turned on, the slow motion element (TD1) 14 outputs an output logical value “0”, which is one of the AND circuits (AND (2)) 32 of the airflow reduction detection circuit 30. Since this is an input, the output logical value of the AND circuit 32 is “0”, and the air volume drop alarm signal is not output from the slow motion element (TD3) 33. That is, immediately after the power is turned on, the detection circuit 30 does not operate, and in fact, after the power is turned on so that the slow motion element (TD1) 14 outputs “1”, the time t1 has passed. . The current signal (1) and the power-on signal (2) are input to the airflow reduction detection circuit 30 even after the time t1 has elapsed, because the reverse rotation is detected and the power is not released. This air volume drop detection circuit 30 works only at normal startup.

  When the air volume is reduced due to clogging of the filter of the electric blower 1, and the energization current of the electric blower 1 is also lowered accordingly and becomes lower than the current set value SET2, the output logic value of the comparison circuit (2) 31 is “ 1 ". As a result of this change, the output (2) of the slow motion element (TD1) 14 is always "1" during normal startup, so the output of the AND circuit (AND (2)) 32 is also set to "1". Change. Then, when the output logical value “1” of the AND circuit (AND (2)) 32 continues for the time t3 of the slow motion element (TD3) 33, the slow motion element (TD3) 33 outputs an air volume lowering alarm signal. To do.

  In response to the output of the alarm signal, a filter clogging alarm is displayed and output from a power converter (not shown) to a monitor device, for example, and a buzzer is output, so that a technician can clean the filter. You will be informed of the need for replacement.

  In the reverse rotation start determination and the collision determination device of the electric blower of the third embodiment, when the actual current value changes due to the fluctuation of the power supply voltage of the electric blower 1 as in the second embodiment, the voltage Even when the actual current value decreases due to the decrease, it can prevent erroneous detection of reverse rotation start and accurately detect reverse rotation start. In addition, during normal start, it detects an air volume drop due to filter clogging and outputs an alarm. (In this case as well, the determination is made based on the current value taking into account the voltage fluctuation), and any of them is detected by using a sensor for detecting the wind pressure in the wind tunnel of the electric blower as in the conventional case. Instead, the detection is basically based on the detected value of the power supply current, so that the reliability is high and the adjustment and maintenance work can be reduced.

  In the third embodiment, the airflow reduction detection circuit 30 is further added to the reverse rotation start detection protection circuit identical to that of the second embodiment shown in FIG. Not limited to this, it is also possible to adopt a configuration in which an air flow rate drop detection circuit 30 is further added to the same reverse rotation start detection protection circuit as that of the first embodiment shown in FIG.

  In each of the above-described embodiments, the logic circuit has been described as positive logic. However, the present invention is not limited to this, and a negative logic configuration that is generally performed may be employed.

The circuit block diagram of the 1st Embodiment of this invention. The circuit block diagram of the 2nd Embodiment of this invention. The circuit block diagram of the 3rd Embodiment of this invention. The circuit block diagram of a prior art example. The graph which shows the electric current-static pressure characteristic of an electric blower. The graph which shows the iQ characteristic and QH characteristic of an electric blower.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric blower 11 Current detector 12 Smoothing circuit 13 Comparison circuit 14 Slow motion element 15 Negative logic circuit 16 AND circuit 17 Slow motion element 18 Flip-flop 19 Negative logic circuit 20 Voltage detector 21 Divider 22 Multiplier 30 Air volume Decrease detection circuit 31 Comparison circuit 32 AND circuit 33 Slow motion element

Claims (3)

Current monitoring means for monitoring the behavior of the energization current from the AC power supply for the electric blower;
The energization current monitored by the current monitoring means is determined to start reverse rotation of the electric blower when the preset reference time has elapsed after the AC power is turned on and when the current is lower than a predetermined value. A reverse rotation start determination device for an electric blower comprising reverse rotation start determination means for outputting. Current monitoring means for monitoring the behavior of the energization current from the AC power supply for the electric blower;
When the energization current monitored by the current monitoring means is less than a predetermined value after the preset first reference time has elapsed after the AC power is turned on, and the electric blower is activated in reverse rotation. Reverse rotation start determination means for determining and outputting;
An electric motor comprising: an erroneous determination prevention means for outputting a final determination of the reverse rotation start when the reverse rotation start determination means continuously outputs the reverse rotation start determination output for a second reference time set in advance A reverse rotation start determination device for a blower. Voltage monitoring means for monitoring the voltage behavior of the AC power supply for the electric blower;
3. The current correction means according to claim 1 or 2, further comprising: a current correction means that corrects a change in the energization current monitored by the current monitoring means based on a voltage behavior monitored by the voltage monitoring means and supplies the correction to the reverse rotation start determination means. The reverse rotation start determination device of the electric blower.

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