JP2015201905A - inverter control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inverter control device having high reliability in which abnormality can be safely and easily diagnosed without directly rotating a motor even under application of a voltage for driving the motor with respect to trouble determination when the inverter control device is operated.SOLUTION: In control of a brushless DC motor, abnormality is determined in accordance with a combination of an input value and a drive output with the same voltage value as application to the motor as processing before the motor is operated, thereby inhibiting the brushless DC motor from operating, whereby abnormality determination of a motor circuit can be safely and easily performed by voltage comparing means for comparing and detecting an induction voltage and a reference voltage generated from the output voltage of an inverter circuit unit and current detecting means for detecting current of the brushless DC motor.

Description

  The present invention relates to a failure determination at the time of driving in an inverter control device of a brushless DC motor, and an electric compressor using the inverter control device and a household refrigerator equipped with a brushless DC motor driven by the inverter control device. The present invention relates to a method that can be used in electrical equipment such as.

  Conventional methods for performing phase loss detection, leakage detection, ground fault detection, phase-to-phase short-circuit detection, etc. of a motor circuit such as a motor, an inverter, and an electric wire connecting the motor to the inverter, There are a method of combining a current transformer for detecting current and a leakage detection relay, a method of using a circuit breaker with leakage detection, a method of using a thermal relay, and the like.

  By the way, when the motor is phase-opened, there is a case where the torque is insufficient, an operation opposite to the intended operation may be performed, and therefore it is preferable not to perform the phase-opening operation. As a method for detecting such a phase failure in the motor circuit, there is a method using a thermal relay with a phase loss detection function, but since it is a bimetal method, it takes time to detect. In addition, in the method of detecting the current of the motor circuit by providing a current transformer (CT) or the like on the motor circuit wire, the number of current detectors is the maximum number of motor circuit wires, that is, the number of motor phases. The size of the apparatus is increased, such as a circuit for determining an abnormal current. Furthermore, when performing motor phase loss detection, leakage detection, ground fault detection, phase short circuit detection, etc., a thermal relay with a phase loss detection function or a current transformer (CT) or the like is used. It is necessary to install a zero-phase current detection current transformer and a leakage detection relay or a breaker with leakage detection on the output side of the inverter separately from the converter and inverter on the motor control converter and inverter input power supply side. Further, the apparatus becomes larger.

  As a method of detecting the above abnormality at the start of motor operation, as described in Patent Document 1, a voltage having a substantially constant level input to the inverter is applied to the inverter transistor and provided on the input side of the inverter device. There has been proposed a method for detecting the above-mentioned abnormality by diagnosing the input current of the inverter detected by using a shunt. In this proposal, the motor current is controlled by turning on and off a substantially constant voltage input to the inverter at a frequency higher than the AC frequency for rotating the motor.

  Further, as in Patent Document 2, when a DC voltage is applied to a motor circuit via an inverter of a control circuit that controls a motor that drives the control target while the operation of the control target that is intermittently operated is stopped, the DC of the inverter The current in the inverter is different from the value when the earth leakage, ground fault, phase loss and short circuit between the motor circuit are generated and the normal value when they are not generated. Using the control to detect the abnormality of the motor circuit by measuring the current of the DC part of the motor and determining the current value, the rotation of the motor does not occur by applying the DC voltage to the motor Even when these diagnoses are made, the DC voltage applied to the motor circuit does not operate the controlled object driven by the motor, and the DC voltage applied to the motor circuit passes a small current sufficient for abnormality diagnosis. By detecting abnormalities as a necessary low voltage without expanding the damage and damage to the motor circuit, blocking the application of voltage to the motor circuit prevents damage to the motor circuit, expansion of damage, malfunction, etc. doing.

JP-A 63-85380 Japanese Patent No. 3108964

  However, in the configuration of Patent Document 1, when the transistor of the inverter is turned on / off at a high frequency, heat generation becomes large. For example, there is a problem that countermeasures for these, such as a cooling method, are required. is there.

  Further, in the configuration of Patent Document 2, there are a plurality of diagnostic patterns having a circuit that must generate a low voltage necessary for flowing a small current for abnormality diagnosis as a direct-current voltage applied to a motor circuit. It had the problem of complexity.

  The present invention solves the above-described conventional problems, and applies a voltage for driving a motor as in Patent Document 1, and safely and more easily diagnoses an abnormality without directly rotating the motor. Therefore, the present invention provides a highly reliable inverter control device.

  In order to solve the above-described conventional problems, an inverter control device of the present invention includes a brushless DC motor including a rotor provided with a permanent magnet and a stator provided with a three-phase winding, and an inverter circuit unit that drives the brushless DC motor; Drive control means for controlling the three-phase output voltage of the inverter circuit section, current detection means for detecting the current value of the brushless DC motor, an induced voltage of the brushless DC motor, and an output voltage of the inverter circuit section Voltage comparison means for comparing and detecting the reference voltage, and the drive control means according to a combination of values inputted by the current detection means and the voltage comparison means by a specific process before driving the brushless DC motor. When the abnormality is determined by the abnormality determination means for performing abnormality determination, the brushless DC module is The data so as not to drive.

  In the inverter control device of the present invention, when the brushless DC motor is driven by a specific process, the motor circuit may have a leakage, a ground fault, an open phase, a short circuit between phases, and the like. In the case of normal operation that is not performed, an abnormality of the brushless DC motor circuit is detected by utilizing the difference in the combination of the current detection means and the voltage comparison means.

  In this case, since the DC voltage is applied to the motor, the motor does not rotate. That is, even when these diagnoses are made, the control target driven by the motor is not operated. Further, since the DC voltage applied to the motor circuit has the same value as the voltage required for driving the motor, if the result of the abnormality diagnosis is normal, it can be operated as it is.

  This eliminates the need for a circuit that generates a low voltage necessary for supplying a small current necessary for driving the motor, which can be realized at a low cost. In addition, since the number of judgment items is small, the judgment time can be shortened. Abnormalities can be detected without expanding the damage and damage to the motor circuit.

  Furthermore, when an abnormality is detected, the application of a voltage to the motor circuit is blocked to prevent damage to the motor circuit, expansion of damage, malfunction, and the like.

Block diagram of the inverter control apparatus in Embodiment 1 of the present invention Internal circuit diagram of voltage comparison means of inverter control device in embodiment 1 Timing chart showing normal input of abnormality determination in the first embodiment Timing chart showing abnormality input of abnormality determination in the first embodiment Timing chart showing abnormality input of abnormality determination in the first embodiment Timing chart showing abnormality input of abnormality determination in the first embodiment Timing chart showing abnormality input of abnormality determination in the first embodiment Timing chart showing abnormality input of abnormality determination in the first embodiment Timing chart showing abnormality input of abnormality determination in the first embodiment Timing chart showing abnormality input of abnormality determination in the first embodiment Timing chart showing abnormality input of abnormality determination in the first embodiment

  The invention according to claim 1 is a brushless DC motor comprising a rotor provided with a permanent magnet and a stator provided with a three-phase winding, an inverter circuit section for driving the brushless DC motor, and a three-phase output voltage of the inverter circuit section. Drive control means for controlling the current, current detection means for detecting the current value of the brushless DC motor, voltage comparison means for comparing and detecting the reference voltage generated by the induced voltage of the brushless DC motor and the output voltage of the inverter circuit unit, When the drive control means makes an abnormality determination by an abnormality determination means that makes an abnormality determination according to a combination of values input by the current detection means by a predetermined output and the voltage comparison means before driving the brushless DC motor. Is one in which the brushless DC motor is not driven.

  Therefore, since it is possible to determine the abnormality of the motor circuit before driving the brushless DC motor, the drive control of the brushless DC motor can be safely performed.

  Moreover, since abnormality determination is performed with the same value as the voltage which drives a brushless DC motor, it can also perform as a series of processes as a starting process.

  Generally, since the bootstrap capacitor used in the inverter drive circuit is used, depending on an appropriate abnormality determination method, the charging to the bootstrap capacitor can be completed after the abnormality determination is completed.

  According to a second aspect of the present invention, in the first aspect of the invention, the drive control means includes position detection determination means for outputting a rotor position detection signal from the induced voltage zero cross point based on the signal input by the voltage comparison means, Based on the output signal from the position detection determination means, the commutation waveform of the inverter circuit unit is controlled by the commutation control means for outputting at a predetermined frequency less than 180 degrees of conduction angle.

  Therefore, the voltage comparison means is characterized by performing the control with the same input without using a dedicated design, an additional circuit, or the like by adopting the same configuration used in normal actual rotational speed control.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, a value is output by comparing two values by a voltage dividing circuit and a comparator.

  Therefore, the input value itself is converted into a voltage that can be input to a low-voltage circuit such as a drive circuit at a low cost by the voltage dividing circuit, and at the same time, the input judgment is made based on the induced voltage based on two patterns of High Low. Processing can be easily performed as logic.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a block diagram of an inverter control device according to Embodiment 1 of the present invention. FIG.
These are the internal circuit diagrams of the voltage comparison means of the inverter control apparatus in Embodiment 1. FIG. FIG. 3 is a timing chart showing normal input for abnormality determination in the first embodiment. 4 to 11 are timing charts showing abnormality input for abnormality determination in the first embodiment.

  In FIG. 1, an inverter control apparatus 100 is connected to a commercial AC power source 101 and an electric compressor 120 having a compression mechanism 120a and a brushless DC motor 103 having a well-known configuration, and the commercial AC power source 101 is used as a DC power source. A rectifying unit 102 for conversion and an inverter circuit unit 104 for driving the brushless DC motor 103 of the electric compressor 120 are provided.

  Further, a drive circuit 105 that drives the inverter circuit unit 104, a terminal voltage of the brushless DC motor 103, a voltage comparison unit 106 that detects the voltage of the rectification unit 102, and a current detection unit that detects a current flowing through the brushless DC motor 103. 107, a microprocessor 108 for controlling the inverter circuit unit 104 is provided.

  The microprocessor 108 includes a position detection determination unit 109 that detects a magnetic pole position of the brushless DC motor 103 with respect to an output signal from the voltage comparison unit 106, and a commutation control unit 110 that generates a commutation signal based on the position detection signal. And.

  Further, the microprocessor 108 detects an abnormality determination of the brushless DC motor 103 with respect to the output state of the inverter circuit unit 104 based on a combination of the output signal from the voltage comparison unit 106 and the output signal of the current detection unit 107. It has.

  Further, in order to drive the drive circuit 105 by the output of the commutation control means 110 for generating a commutation signal based on the output from the position detection determination means 109, the rotational speed is calculated and detected. Drive control means 112 is provided that performs PWM modulation operation on the output voltage in accordance with the rotation speed and the rotation speed command or the phase difference and outputs the result.

  The brushless DC motor 103 includes a three-phase winding stator 103a and a rotor 103b.

  The stator 103a is composed of stator windings 103u, 103v, and 103w, and the rotor 103b has a magnet embedded structure in which permanent magnets 103α, 103β, 103γ, 103δ, 103ε, and 103ζ are arranged to generate reluctance torque. is there.

  The inverter circuit unit 104 includes six switching transistors Tru, Trx, Trv, Try, Trw, Trz connected in a three-phase bridge, and free-wheeling diodes Du, Dx, Dv, Dy, Dw, Dz connected in parallel to the switching transistors Tru, Trx, Trv, Try, Trw, Trz, respectively. It is configured.

  As shown in FIG. 2, the voltage comparison means 106 is composed of a voltage dividing circuit and comparators 106a, 106b, 106c. The voltage of the rectifier 102 applied to the brushless DC motor 103 is a bus voltage, and the bus voltage is used as a source. It falls within the rating from the reference voltage that is within the comparator rating and divided to be half the voltage dividing ratio with respect to the comparison voltage on the other side and the stator windings 103u, 103v, 103w of the brushless DC motor 103. The terminal voltage signals based on the induced voltage obtained through the voltage dividing circuit are compared by the comparators 106a, 106b and 106c to obtain the position detection signals PdU, PdV and PdW.

In the first embodiment, the reference voltage is divided based on the bus voltage, but the midpoint potential of the three-phase bridge connection may be used as the reference voltage.
The current detection means 107 is composed of an operational amplifier (not shown) and the like, and is a brushless DC
A current value flowing through the motor 103 is obtained by amplifying a minute voltage value at both ends of the shunt resistor with an operational amplifier, and converted from a used shunt resistance value to a current value to obtain a current signal Ar.

  The position detection determination unit 109 obtains the position signal of the rotor 103b from the output signal of the voltage comparison unit 106 and generates a position detection signal.

  The commutation control means 110 calculates the commutation timing based on the position detection signal of the position detection determination means 109, and generates commutation signals for the switching transistors Tru, Trx, Trv, Try, Trw, and Trz.

  The abnormality determination unit 111 includes position detection signals PdU, PdV, PdW obtained by the voltage comparison unit 106 when the drive control unit 112 drives output signals to the switching transistors Tru, Trx, Trv, Try, Trw, Trz. Abnormality of the inverter circuit unit 104 and the brushless DC motor 103 is determined based on the current signal Ar.

  The drive control unit 112 synthesizes the commutation signal of the commutation control unit 110 and the PWM modulation signal, generates a drive signal for turning ON / OFF the switching transistors Tru, Trx, Trv, Try, Trw, Trz, and the drive circuit 105. Output to.

  The drive circuit 105 performs ON / OFF switching of the switching transistors Tru, Trx, Trv, Try, Trw, and Trz based on the drive signal to drive the brushless DC motor 103.

  Next, processing for performing abnormality determination by the abnormality determination unit 111 when the brushless DC motor 103 is driven will be described with reference to FIGS.

  In FIG. 3, before driving the brushless DC motor 103, the drive control unit 112 starts abnormality determination from a state where all of the switching transistors Tru, Trx, Trv, Try, Trw, and Trz are OFF as shown in t <b> 1. At this time, the normal values of the position detection signals PdU, PdV, PdW and the current signal Ar are all in the Lo state (or 0) like t201a, t201b, t201c, and t201d.

  Here, if any of the switching transistors Tru, Trv, Trw is short-circuited, or if any of the comparators 106a, 106b, 106c in the voltage comparison means 106 has a Hi output fault, the comparators 106a, Regardless of the value of the bus voltage that is the source of the reference potential to be compared by 106b and 106c, a position detection signal corresponding to the location corresponding to the failure is output Hi as shown at t1 in FIG. When the switching transistor Tru is short-circuited or the comparator 106a has a Hi output failure, the position detection signal PdU outputs a Hi output signal as at t211a. Needless to say, the comparator 106a has a Hi output failure. However, when the switching transistor Tru has a failure, the reference potential is ½ of the bus voltage and the comparison value is the bus voltage as the voltage ratio. Since it becomes larger than this, Hi is output.

  When the switching transistor Trv is short-circuited or the comparator 106b has a Hi output failure, the position detection signal PdV outputs a Hi output signal as shown at t211b. When the switching transistor Trw is short-circuited or the comparator 106c has a Hi output failure, the position detection signal PdW outputs a Hi output signal as indicated by t211c. When two or more places have failed at the same time, the above combination is obtained.

Further, when one of the switching transistors Trx, Try, Trz is short-circuited, in a known bootstrap capacitor configured as the drive circuit 105, charging to the bootstrap capacitor corresponding to the short-circuited switching transistor is short-circuited. The current signal Ar is output as indicated by t221d of t1 in FIG. 5 regardless of which one is short-circuited by starting the switching transistor and the shunt resistor monitored by the current detection means 107.

  When any of the switching transistors Tru, Trv, Trw is short-circuited, or when any of the comparators 106a, 106b, 106c in the voltage comparison means 106 has a Hi output fault, the switching transistors Trx, Try , Trz are combined with the case where one of them is short-circuited, it becomes a combination of the abnormality signals of t211a, t211b, t211c and t221d which are the respective abnormality determination criteria shown in FIGS.

  As described above, the drive control unit 112 can detect a short-circuit failure of the switching transistors Tru, Trx, Trv, Try, Trw, and Trz without applying an output signal to the switching transistors Tru, Trx, Trv, Try, Trw, and Trz. In performing other abnormality determinations to be performed thereafter, applying the same value as the voltage value applied when driving the brushless DC motor 103 as the abnormality determination voltage does not become a risk factor.

  There is no short-circuit fault in the switching transistors Tru, Trx, Trv, Try, Trw, Trz, and there is no Hi output fault in the comparators 106a, 106b, 106c in the voltage comparison means 106. The process proceeds to determination process t2.

  After t2, it is a step of performing failure confirmation for each phase. In the first embodiment, the U phase corresponding to the stator winding 103u is t2 and t3, and the stator winding is t4 and t5. The V phase corresponding to the line 103v is defined as a step of determining abnormality of the W phase corresponding to the stator winding 103w at t6 and t7.

  Here, since the determination order for the stator windings 103u, 103v, and 103w does not matter, there is no problem even if 103v is performed before 103u, and the abnormality determination process order is not limited to the first embodiment. Absent. Regardless of the order of execution steps, when abnormality determination is performed, the subsequent determination is not performed, and the process is stopped without driving the brushless DC motor 103.

  At t2, the switching transistor Trx connected to the negative side of the rectifier 102 that drives the stator winding 103u is driven. At normal time, charging of the bootstrap capacitor in the drive circuit 105 is started at this time, so that the current signal Ar is input as shown by t202d in FIG. 3 and the switching transistor Trx has an open failure. Since the charging of the bootstrap capacitor in the drive circuit 105 is not started due to the disconnection, the current signal Ar is not output as t212d in FIG. 6 (it remains 0).

  In addition, when the brushless DC motor 103 is grounded, charging of the bootstrap capacitor is started. However, since charging is performed through the ground, a current flows to the shunt resistor detected by the current detecting unit 107. The current signal Ar is not output. Charging the bootstrap capacitor when the brushless DC motor 103 is not driven is normally performed by supplying a voltage from a low-voltage circuit such as 15 V, so that it is possible to safely perform an abnormality determination against a ground fault. Can be done.

  Therefore, it is possible to determine the open failure of the switching transistor Trx and the ground fault of the brushless DC motor 103 based on the current signal Ar.

  If the shunt resistor that is the detection source of the current detection means 107 is short-circuited, a potential difference does not occur at both ends of the shunt resistance, so the current signal Ar is not output. Can do.

  At t3, the switching transistor Tru connected to the + side of the rectifying unit 102 that drives the stator winding 103u is driven. At normal time, since charging of the bootstrap capacitor in the drive circuit 105 is started at this time, the switching transistor Tru can be driven, and the positive side of the rectifier 102 and the stator winding 103u are electrically connected. As a result, the comparator 106a When a value is input to one side by a voltage dividing circuit corresponding to the bus voltage, the value becomes equal to or higher than a value by a voltage dividing circuit corresponding to ½ of the bus voltage serving as the reference potential, as shown by t203a in FIG. Pdu outputs a Hi output signal, but when the switching transistor Tru is in an open failure, the + side of the rectifying unit 102 and the stator winding 103u are not conductive, so that 0 is input to one side of the comparator 106a. By being less than the value obtained by the voltage dividing circuit corresponding to 1/2 of the bus voltage serving as the reference potential, And it remains Lo output signal as in the seventh T223a. Needless to say, when the comparator 106a has a Lo output failure, the Lo output signal remains unchanged.

  Therefore, at t3, it is possible to perform abnormality determination of the short-circuit fault of the switching transistor Tru and the Lo output fault of the comparator 106a.

  At t4, the switching transistor Try connected to the negative side of the rectifying unit 102 that drives the stator winding 103v is driven. At normal time, charging of the bootstrap capacitor in the drive circuit 105 is started at this time, so that the current signal Ar is input as shown by t204d in FIG. 3 and the switching transistor Try has an open failure. Since the charging of the bootstrap capacitor in the drive circuit 105 is not started due to the disconnection, the current signal Ar is not output as t214d in FIG.

  Here, when the impedance value of the stator winding 103v is small, or at t2, the switching transistor Trx is driven and the charging time for the bootstrap capacitor for driving the switching transistor Tru is long. In this case, the bootstrap capacitor necessary for driving the switching transistor Trv and the switching transistor Trw is also simultaneously charged through the stator winding 103v.

  The first embodiment has been described on the premise that charging to the bootstrap capacitor corresponding to another switching transistor is not completed. Due to the stator windings 103u, 103v, 103w and the abnormality determination time, the charging to the bootstrap capacitor corresponding to the other switching transistor is completed, and the next switching transistor is driven to charge the corresponding bootstrap capacitor. In other words, when the current signal Ar is not output as in t214d of FIG. 8, in the case of the first embodiment, when the switching transistor Try is driven and the bootstrap capacitor cannot be charged, t1 to t3 Since it has been confirmed that the switching transistor Trv is short-circuited and that there is no abnormality in the switching transistor Trx, the switching transistor Trv and the switching transistor Trx are driven before the abnormality determination at t4, although not shown. More, since in the state eliminating the charge of the bootstrap capacitor corresponding to the switching transistor Trv, it is necessary to perform the abnormality determination process of the open-circuit failure of the switching transistor Try at t4.

  At time t2, in order to charge the bootstrap capacitor corresponding to the switching transistor Trv through the stator windings 103u and 103v, the current signal Ar at t204d at t4 is at least the current signal Ar at t202d at t2. Therefore, if the current signal Ar has the same value without change at t202d and t204d, one of the stator windings 103u and 103v is missing, and the missing phase can be determined.

  In addition, when the brushless DC motor 103 is grounded, charging of the bootstrap capacitor is started. However, since charging is performed through the ground, a current flows to the shunt resistor detected by the current detecting unit 107. However, the current signal Ar is not output, but since the ground fault of the brushless DC motor 103 can be determined at time t3, there is no possibility of a ground fault here.

  At t5, the switching transistor Trv connected to the + side of the rectifying unit 102 that drives the stator winding 103v is driven. At normal time, charging of the bootstrap capacitor in the drive circuit 105 is started at this time, so that the switching transistor Trv can be driven, and the positive side of the rectifying unit 102 and the stator winding 103v are electrically connected. As a result, the comparator 106b When a value is input to one side by a voltage dividing circuit corresponding to the bus voltage, the value becomes equal to or greater than a value by a voltage dividing circuit corresponding to ½ of the bus voltage serving as the reference potential, as shown by t205b in FIG. Pdv outputs a Hi output signal. However, when the switching transistor Trv has an open failure, the + side of the rectifying unit 102 and the stator winding 103v do not conduct, and therefore one side of the comparator 106b is input with 0. By being less than the value obtained by the voltage dividing circuit corresponding to 1/2 of the bus voltage serving as the reference potential, And it remains Lo output signal as in the ninth T225b. Needless to say, when the comparator 106b has a Lo output failure, the Lo output signal remains unchanged.

  Therefore, at t5, it is possible to determine whether the switching transistor Trv is short-circuited or the comparator 106b is out of Lo.

  At t6, the switching transistor Trz connected to the negative side of the rectifying unit 102 that drives the stator winding 103w is driven. At normal time, charging of the bootstrap capacitor in the drive circuit 105 is started at this time, so that the current signal Ar is input as shown by t205d in FIG. 3 and the switching transistor Trz has an open failure. Since the charging of the bootstrap capacitor in the drive circuit 105 is not started due to the disconnection, the current signal Ar is not output as t216d in FIG. 10 (it remains 0).

At time t2, in order to charge the bootstrap capacitor corresponding to the switching transistor Trw via the stator windings 103u and 103w, the current signal Ar at t206d at t6 is at least the current signal Ar at t202d at t2. Therefore, if the current signal Ar has the same value without change at t202d and t206d, either one of the stator windings 103u and 103w is missing, and the missing phase can be determined. (Here, in the order of abnormality determination, if the stator winding 103u is out of phase, it can be determined at t4, and therefore, only the stator winding 103w is determined to be out of phase.)
In addition, when the brushless DC motor 103 is grounded, charging of the bootstrap capacitor is started. However, since charging is performed through the ground, a current flows to the shunt resistor detected by the current detecting unit 107. However, the current signal Ar is not output, but since the ground fault of the brushless DC motor 103 can be determined at time t3, there is no possibility of a ground fault here.

At t7, the switching transistor Trw connected to the + side of the rectifying unit 102 that drives the stator winding 103w is driven. At normal time, since charging of the bootstrap capacitor in the drive circuit 105 is started at this time, the switching transistor Trw can be driven, and the positive side of the rectifier 102 and the stator winding 103w are electrically connected. As a result, the comparator 106c When a value is input to one side by a voltage dividing circuit corresponding to the bus voltage, the value becomes equal to or more than a value by a voltage dividing circuit corresponding to ½ of the bus voltage serving as the reference potential, as shown by t207c in FIG. Pdw outputs a Hi output signal. However, when the switching transistor Trw has an open failure, the + side of the rectifying unit 102 and the stator winding 103w are not conductive, and therefore one side of the comparator 106c is input with 0. By being less than the value obtained by the voltage dividing circuit corresponding to ½ of the bus voltage serving as the reference potential, 11 remains at Lo output signal as t227c of. Needless to say, when the comparator 106c has a Lo output failure, the Lo output signal remains unchanged.

  Therefore, at t7, it is possible to determine whether the switching transistor Trw is short-circuited or the comparator 106c is out of Lo.

  As described above, the abnormality determination can be determined by the same voltage as the voltage applied to the brushless DC motor 103 by combining the circuit characteristics and the abnormality determination method without driving the brushless DC motor 103. Therefore, the abnormality determination can be realized at a low cost.

  Also, the determination method is not complicated, and it is possible to detect a short-circuit failure of the switching transistor without driving the switching transistor, and therefore it is possible to determine an abnormality very safely.

  As described above, since it is possible to determine the ground fault, phase loss, and component failure of the inverter circuit unit 104 without driving the brushless DC motor 103, high reliability can be obtained. Even when the inverter control device 100 according to the first embodiment is used for the electric compressor 120 provided, it is possible to provide a highly reliable one.

  Further, in the article storage device such as a refrigerator equipped with an electric compressor 120, a condenser, a decompression device, and a refrigeration cycle (all not shown) in which an evaporator is connected in a ring shape, the electric compressor 120 is implemented in this embodiment. The reliability can be improved by determining the abnormality using the inverter control device 100 according to the first embodiment.

  As described above, the inverter control device according to the present invention uses the inverter control device because it can determine the phase failure, ground fault, and component failure of the drive circuit of the brushless DC motor before driving the brushless DC motor. It is useful for household electric appliances such as air conditioners, refrigerators and washing machines, and electric vehicles.

DESCRIPTION OF SYMBOLS 100 Inverter control apparatus 103 Brushless DC motor 103a Stator 103b Rotor 104 Inverter circuit part 106 Voltage comparison means 107 Current detection means 109 Position detection determination means 110 Commutation control means 111 Abnormality determination means 112 Drive control means 120 Electric compressor

Claims (3)

A brushless DC motor comprising a rotor provided with a permanent magnet and a stator provided with a three-phase winding; an inverter circuit section for driving the brushless DC motor; and a drive control means for controlling a three-phase output voltage of the inverter circuit section; Current drive means for detecting a current value of the brushless DC motor; and voltage comparison means for comparing and detecting a reference voltage generated by an induced voltage of the brushless DC motor and an output voltage of the inverter circuit unit, the drive control means When an abnormality is determined by an abnormality determination unit that performs an abnormality determination according to a combination of values input by the current detection unit and the voltage comparison unit by a predetermined process before driving the brushless DC motor, An inverter control device characterized by not driving a brushless DC motor. The drive control means includes position detection determination means for outputting a rotor position detection signal from an induced voltage zero cross point based on a signal input by the voltage comparison means, and an output signal of the inverter circuit unit based on an output signal from the position detection determination means. 2. The inverter control device according to claim 1, wherein the commutation waveform is controlled by a commutation control means that outputs the commutation waveform at a predetermined frequency less than 180 degrees of conduction. The inverter control device according to claim 1, wherein the voltage comparison unit outputs a value by comparing two values with a voltage dividing circuit and a comparator.

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