JP2013090475A - Inverter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably detect abnormality occurring in a motor driving a cooling fan without providing a special abnormality detection function to a cooling fan device.SOLUTION: An inverter device according to one embodiment includes a motor driving a cooling fan. Voltage measurement means measures a voltage between terminals of the motor when a driving voltage is applied to the motor. Abnormality detection means determines that abnormality occurs in the motor when a ripple component which is caused by rotation of the motor is not detected in the voltage measured by the voltage measurement means when the driving voltage is applied to the motor according to an operation signal.

Description

  Embodiments described herein relate generally to an inverter device including a cooling fan.

  Inside the inverter device, a heat generating component such as a semiconductor element, a heat sink for dissipating heat generated by these heat generating components, and a cooling fan device for blowing air to the heat sink are provided. FIG. 8 shows a drive circuit of the cooling fan device. The cooling fan device 1 includes a cooling fan 2 and a fan motor 3. The fan motor 3 is driven by a DC voltage (for example, 24 V) supplied from the power supply circuit 4 via the MOSFET 5.

  The power supply circuit 4 is, for example, an insulation type DC-DC converter including a switching transformer 6, and includes a switching circuit 7 on the primary side and a rectifier circuit 10 including a diode 8 and a smoothing capacitor 9 on the secondary side. It has. In a general inverter device, the 24V voltage system of the power supply circuit 4 is supplied to the fan motor 3 and is provided as a shared power source that can be used by the user through a control terminal block.

  If the inverter device is continuously operated while the cooling fan device 1 is broken, the temperature in the inverter device rises, which may cause a thermal failure. In a general failure detection method of the cooling fan device 1, the temperature inside the heat sink or the device is measured, and when the measured temperature exceeds a reference value, the operation of the inverter is stopped as a temperature abnormality. However, in this method, there is a certain delay time from when the cooling fan device 1 breaks down until it is determined that the temperature is abnormal. In the meantime, since the operation is continued in a state where the inverter device is not normally cooled, there is a possibility that the life of the semiconductor element and other parts may be shortened.

Japanese Patent No. 2512326 JP 11-55935 A JP 2009-268217 A

  In order to avoid a delay in detecting an abnormality of the fan motor 3, a cooling fan device having a special function for facilitating the detection of an abnormality such as a function of outputting a signal according to the rotation speed of the fan motor 3 is provided. Use it. However, such a cooling fan device has a complicated configuration, which reduces reliability and increases costs.

  Therefore, an inverter device is provided that can reliably detect an abnormality that has occurred in a motor that drives a cooling fan without giving the cooling fan device a special abnormality detection function.

  The inverter device of the embodiment includes a motor that drives a cooling fan. The voltage measuring unit measures a voltage between terminals of the motor when a driving voltage is applied to the motor. The abnormality detector means that when a drive voltage is applied to the motor in accordance with the operation signal, an abnormality occurs in the motor when a ripple component generated with the rotation of the motor is not detected in the voltage measured by the voltage measuring means. It is determined that

The block diagram of the drive circuit of the fan motor which shows 1st Embodiment Electrical block diagram of the inverter device Flow chart of fan motor abnormality detection processing (A) is the voltage Va between the terminals of the fan motor when the fan motor is rotating normally, and (b) is a waveform diagram of the output voltage Vb applied to another load. Waveform diagram when capacitance value Ca is set to 330 μF Waveform diagram when the capacitance value Ca is set to 10 μF The partial flowchart of the abnormality detection process of the fan motor which shows 2nd Embodiment 1 equivalent diagram showing the prior art

(First embodiment)
The first embodiment will be described with reference to FIGS. In FIG. 1, the same components as those in FIG. As shown in FIG. 2, an AC power supply 12 is connected to the power input terminal of the inverter device 11, and a motor 13 is connected to the load output terminal. The rectifier circuit 14 rectifies the three-phase AC voltage of the AC power supply 12 using a bridge-connected diode and outputs it between the DC power supply lines 15 and 16 to which the smoothing capacitor 17 is connected. The inverter circuit 18 has a configuration in which switching elements such as IGBTs are connected in a three-phase bridge between the DC power supply lines 15 and 16, and outputs a three-phase AC voltage to the motor 13 by performing a switching operation according to a gate signal.

  The control circuit 19 is mainly composed of a microcomputer having a CPU, a RAM, a ROM, an EEPROM, an input / output port, an A / D converter, a timer, a PWM signal forming circuit, a communication means, and the like. The ROM stores an inverter control program and an abnormality determination program for the fan motor 3. The EEPROM has various parameters such as acceleration time, deceleration time, upper limit frequency, lower limit frequency, multi-speed operation frequency, and input / output terminal selection. It is remembered.

  The operation panel 20 is provided in front of the casing of the inverter device 11. The operation panel 20 includes operation means such as an operation key (RUN key) 20a, a stop key (STOP key) 20b, and a segment display unit 20c, as well as operation means such as an up key, a down key, a mode key, an enter key, and a volume dial. Display means such as a unit display lamp and a mode display lamp.

  In accordance with the inverter control program read from the ROM, the control circuit 19 calculates an output voltage based on the operation command and the frequency command input from the operation panel 20 or the outside of the apparatus, and outputs a gate signal having a PWM waveform. The gate signal is given to the switching element of the inverter device 11 through the drive circuit 21. Further, display output processing to the operation panel 20 and communication processing with an external device (not shown) such as a sequencer are executed. Further, the control circuit 19 as an abnormality detection means executes an abnormality detection process for the fan motor 3 in accordance with the abnormality determination program read from the ROM.

  The power supply circuit 22 inputs the DC voltage VDC between the DC power supply lines 15 and 16, and supplies the DC voltage supplied to the internal circuit of the inverter device 11 and the external device (sequencer, contact output input) connected to the control terminal block 23. DC voltage supplied to the circuit) is generated. For example, 5V and 3.3V are supplied to the microcomputer, and 24V is supplied to the cooling fan device 1, the operation panel 20, and the external device.

  The cooling fan device 1 is a device that blows and cools a heat generating component such as a diode of the rectifier circuit 14 and a switching element of the inverter circuit 18 and a heat sink to which the heat generating component is attached. FIG. 1 shows the electrical configuration (24V system) of the cooling fan device 1 and the power supply circuit 22. The cooling fan device 1 includes a cooling fan 2 and a fan motor 3. The fan motor 3 is a brushless or brushed DC motor and rotates at a speed corresponding to the applied voltage. However, when the aging deterioration occurs, the rotation speed with respect to the applied voltage tends to decrease.

  The power supply circuit 22 is a DC-DC converter that includes the switching circuit 7 on the primary side and is insulated by the switching transformer 6. The secondary side includes a power supply system 22A to which the fan motor 3 is connected as a load, and a power supply system 22B to which a load other than the fan motor 3, such as the operation panel 20 or an external device, is connected. The user can use the power supplied from the power supply system 22 </ b> B through the control terminal block 23. The power supply systems 22A and 22B are power circuits composed of diodes 8a and 8b and smoothing capacitors 9a and 9b, each of which receives the secondary side voltage of the switching transformer 6, but are different power supplies that are electrically separated and independent from each other. The system is configured.

  An output line of the power supply system 22A is connected to the fan motor 3 via a MOSFET 5 as a switch circuit. When the operation key 20a is pressed, the control circuit 19 outputs a gate signal having a PWM waveform to drive the load, and outputs the operation signal to turn on the MOSFET 5 to rotate the fan motor 3. . A temperature detecting means such as a thermistor is attached to the heat sink. When the stop key 20b is pressed, the control circuit 19 continues to output the operation signal of the fan motor 3 until the detected temperature falls below a predetermined value or until a predetermined time elapses.

  Between the output lines of the power supply system 22A (between the smoothing capacitor 9a and the MOSFET 5), the voltage across the terminals of the fan motor 3 when the drive voltage Va is applied to the fan motor 3 according to the operation signal is divided. A voltage measuring circuit 24 (voltage measuring means) for measuring by pressing is connected. The measurement voltage Vm is converted into a digital value by the A / D converter of the control circuit 19 and input to the CPU.

  The capacitance value Cb of the smoothing capacitor 9b of the power supply system 22B is set to a large value (for example, 330 μF) in order to reduce the ripple component of the smoothed voltage Vb as much as possible. On the other hand, the capacitance value Ca of the smoothing capacitor 9a of the power supply system 22A appears at a level at which the ripple component generated by the rotation of the fan motor 3 can be detected in the measured voltage Vm when the fan motor 3 is rotating. Thus, it is set to a value (for example, 10 μF) smaller than the capacitance value Cb of the smoothing capacitor 9b.

  FIG. 3 is a flowchart of the abnormality detection process of the fan motor 3 that is executed by the control circuit 19 according to the abnormality determination program. The control circuit 19 performs A / D conversion and inputs the measurement voltage Vm when the drive voltage Va is applied to the fan motor 3 according to the operation signal (step S1). Then, the measured voltage Vm is filtered to extract a ripple component generated with the rotation of the fan motor 3 (step S2). This ripple component is a ripple voltage generated in synchronization with the rotation of the fan motor 3.

When the fan motor 3 rotates, the number of magnetic flux linkages always changes, and when the magnetic pole passes through the slit portion, the change becomes significant. Therefore, torque ripple is generated due to a change in the number of magnetic flux linkages, and the torque repeatedly fluctuates with a constant period and a constant width. Theoretically, the torque ripple frequency f (ripple) is expressed by the following equation (1). For example, when the fan motor 3 having the number of poles p of 4 is operated at 4500 rpm, f (ripple) = 300 Hz, and torque ripple is generated every 3.33 ms (= 1 / f (ripple)).
f (ripple) = number of poles p × rotational speed (rpm) / 60 (1)

  The control circuit 19 determines whether or not there is a ripple component in the measured voltage Vm (step S3). If there is (YES), it is determined that the fan motor 3 is rotating normally (step S4). On the other hand, if not (NO), it is determined that an abnormality such as the rotation of the fan motor 3 has stopped (step S5).

  FIG. 4A shows the voltage Va between the terminals of the fan motor 3 when the fan motor 3 is rotating normally (capacitance value Ca = 10 μF). It can be seen that a ripple component synchronized with the rotation of the fan motor 3 is superimposed on the voltage Va between the terminals. A similar ripple component also appears in the measurement voltage Vm obtained by dividing the inter-terminal voltage Va. On the other hand, no ripple component appears when the fan motor 3 is not rotating. Therefore, whether or not the fan motor 3 is rotating normally can be determined based on whether or not a ripple component is detected in the measurement voltage Vm input via the A / D converter. FIG. 4B shows the output voltage Vb of the power supply system 22B (capacitance value Cb = 330 μF). Since the power supply system 22B is sufficiently smoothed, no ripple component appears in the output voltage Vb.

Next, a method for setting the capacitance value Ca of the smoothing capacitor 9a will be described with reference to FIGS. If the voltage across the smoothing capacitor 9a is Va, the charge Q of the smoothing capacitor 9a is given by equation (2).
Q = Ca × Va (2)

Assuming that the current flowing through the smoothing capacitor 9a is Ia, equations (2) to (3) are obtained.

  Therefore, the value of the ripple voltage ΔVa necessary for determining that the fan motor 3 is rotating normally is determined, and the integration value of the current Ia is obtained from the test using the smoothing capacitor 9a having a somewhat large capacitance value. The value of the capacitance value Ca can be obtained. However, since the integral value of the current Ia is influenced by the capacitance value of the smoothing capacitor 9a to be used, it is finally fine-tuned by confirming whether or not a desired ripple voltage ΔVa is generated in an actual machine test. There is a need to.

A specific example of determining the capacitance value Ca of the smoothing capacitor 9a will be described. 5 and 6 show measured waveforms of the voltage Va (1 V / div) and the current Ia (20 mA / div) across the smoothing capacitor 9a (1 ms / div). FIG. 5 shows waveforms when the fan motor 3 is normally rotated using the smoothing capacitor 9a having a large capacitance value 330 μF. From this measurement result, since the integral value of the current Ia during the change time dt is 26 × 10 ⁻⁶ , when the desired ripple voltage ΔVa (voltage difference) is, for example, 2.6 V, the capacitance value Ca of the smoothing capacitor 9 a is Calculated as 10 μF.

FIG. 6 shows a waveform when the capacitance value Ca is actually set to 10 μF. However, the ripple voltage ΔVa at this time is 1.3V, which is insufficient with respect to the target value of 2.6V. The integral value of the current Ia during the change time dt at this time is 10 × 10 ⁻⁶ . Therefore, when the capacitance value Ca of the smoothing capacitor 9a is calculated again, it becomes 3.8 μF. In this way, adjustment may be made so that the desired ripple voltage ΔVa (voltage difference) appears using theoretical calculation and actual machine test.

  According to this embodiment, since the abnormality of the fan motor 3 is detected based on whether or not the ripple component is detected in the measured voltage Vm of the inter-terminal voltage of the fan motor 3, the delay time from the occurrence of the abnormality to the detection of the abnormality Is very short, and it is possible to prevent the operation from continuing while the inverter device 11 is not normally cooled. Since the cooling fan device 1 itself does not need to have a special abnormality detection function, the abnormality of the fan motor 3 can be detected while using the cooling fan device 1 of the standard specification similar to the conventional one. In addition, since the voltage measurement circuit 24 and the abnormality detection program for the fan motor 3 can be added to the conventional configuration, it is possible to prevent the complication of the configuration and the increase in cost in order to detect the abnormality of the cooling fan device 1 as much as possible. Can do.

  The secondary side of the power supply circuit 22 is separated into a power supply system 22A provided exclusively for the fan motor 3 and a power supply system 22B to which a load other than the fan motor 3 is connected. Since the capacitor 9a has a small capacitance value, the ripple voltage generated with the rotation of the fan motor 3 can be reliably detected. In addition, since the smoothing capacitor 9a can be reduced in size, an increase in device size and cost due to the separation of the power supply system can be suppressed as much as possible.

(Second Embodiment)
FIG. 7 is a flowchart of an additional process executed in place of step S4 of the abnormality detection process for the fan motor 3 shown in FIG. When the control circuit 19 determines that there is a ripple component in the measurement voltage Vm in step S3, the control circuit 19 measures the ripple period (step S11) and calculates the rotational speed of the fan motor 3 (step S12). Subsequently, it is determined whether or not the detected rotation speed is lower than a predetermined determination threshold value (step S13). If it is determined that it is not low (NO), it is determined that the fan motor 3 is rotating normally (step S14). If it is determined to be low (YES), it is determined that the fan motor 3 has deteriorated over time (step S15).

  The determination threshold value used in this case is a value obtained by multiplying the rated rotational speed by a certain reduction rate (for example, 0.8), or the ability to cool the heat-generating component is reduced, causing a thermal failure to the component of the inverter device 11. It is set to the value of the rotational speed at which there is a possibility of waking up. Since the rotation speed of the fan motor 3 increases as the applied voltage increases, the determination threshold value may be corrected in accordance with the measured voltage Vm (inter-terminal voltage Va) in order to avoid variations in determination due to deviations in the applied voltage.

  According to the present embodiment, not only the determination of whether the fan motor 3 is rotating or stopped but also the decrease in the rotation speed of the fan motor 3 is determined. The accompanying cooling capacity drop abnormality can also be detected. Accordingly, it is possible to prompt the user to replace the cooling fan device 1 before the all-stop abnormality occurs in the fan motor 3.

(Other embodiments)
In addition to the plurality of embodiments described above, the following configuration may be adopted.
Although the power supply system 22A to which only the fan motor 3 is connected and the power supply system 22B to which a load other than the fan motor 3 is connected are separated, it is not always necessary to separate them.
If the ripple component appears in the measurement voltage Vm at a level where the fan motor 3 is rotating, it is not necessary to set the capacitance value of the smoothing capacitor 9a to be small.

  According to the embodiment described above, when a driving voltage is applied to the motor that drives the cooling fan, the motor is detected when the ripple component generated by the rotation of the motor is not detected in the voltage measured by the voltage measuring means. It is determined that an abnormality has occurred. This makes it possible to reliably detect an abnormality that has occurred in the motor that drives the cooling fan, without providing the cooling fan device with a special abnormality detection function.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof in the same manner as included in the scope and gist of the invention.

  In the drawing, 2 is a cooling fan, 3 is a fan motor (motor), 9a is a smoothing capacitor, 11 is an inverter device, 19 is a control circuit (abnormality detection means), 22 is a power supply circuit (DC power supply circuit), and 22A and 22B are A power supply system 24 is a voltage measurement circuit (voltage measurement means).

Claims (5)

An inverter device including a motor for driving a cooling fan,
Voltage measuring means for measuring a voltage between terminals of the motor when a driving voltage is applied to the motor;
When a drive voltage is applied to the motor in accordance with an operation signal, an abnormality has occurred in the motor when a ripple component generated with the rotation of the motor is not detected in the voltage measured by the voltage measuring means. An inverter device comprising an abnormality detecting means for determining. The motor is a DC motor,
A DC power supply circuit that has a smoothing capacitor and generates a drive voltage to be applied to the motor,
The capacitance value of the smoothing capacitor of the DC power supply circuit is set small so that the ripple component appears at a detectable level in the voltage measured by the voltage measuring means when the motor is rotating. The inverter device according to claim 1.   3. The inverter device according to claim 2, wherein the DC power supply circuit that supplies a drive voltage to the motor is configured by a power supply system that is different from a DC power supply circuit that supplies power to a load other than the motor.   The abnormality detection means detects the rotation speed of the motor based on a ripple period appearing in the voltage measured by the voltage measurement means when a drive voltage is applied to the motor, and determines the rotation speed. The inverter device according to claim 1, wherein the motor device is determined to have deteriorated when the value falls below a threshold value.   The inverter apparatus according to claim 4, wherein the abnormality detection unit corrects the determination threshold according to the voltage measured by the voltage measurement unit.

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