JP2009011014A - Inverter controller, electric compressor, and household electrical equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reliable inverter controller which prevents stop, due to step-out in momentary power failure or rapid voltage change, by changing the angle of energization instantaneously, according to the voltage of a DC voltage part. <P>SOLUTION: It is equipped with a DC voltage detecting part 209 which detects the voltage value of DC power voltage supplied to an inverter circuit part 205 and an angle-of-energization control unit 218 which changes the angle of energization in the inverter circuit part 205, in the range of less than 180°, according to the voltage value detected with the DC voltage detecting part 209, so that position detecting zone can be increased by reducing the angle of energization, when the number of revolutions changes largely due to rapid voltage change, and the magnetic pole position of a rotor can be surely confirmed, and the step out due to the voltage change can be prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to wide-angle energization control in an inverter control device for a brushless DC motor.

  Conventionally, this type of inverter control device has been proposed to expand the operating range of the inverter and increase the output of the inverter control device by performing wide-angle control that widens the energization angle to an electrical angle of 120 degrees or more ( For example, see Patent Document 1).

  In general, a 120-degree energization waveform has been adopted as an inverter waveform control so far from the viewpoint of ease of control. In a system that drives a brushless DC motor, although each of the positive and negative electrical angles is 180 degrees, each phase switch of the inverter is made to conduct only by an electrical angle of 120 degrees, and the remaining electrical angle of 60 degrees. The section was uncontrolled.

  Therefore, in the non-control period, the inverter cannot output a desired voltage, and the DC voltage utilization rate of the inverter is low. The terminal voltage of the brushless DC motor is reduced due to the low DC voltage utilization rate, and the operating range is narrowed, that is, the maximum rotational speed is lowered.

  Therefore, in Patent Document 1, the energization width of the voltage source inverter is set to a predetermined width greater than 120 degrees and equal to or less than 180 degrees in electrical angle, and the non-control section is set to less than 60 degrees in electrical angle. As a result, the motor terminal voltage is increased to widen the operating range.

  In recent years, permanent magnets have been embedded inside the rotor to increase the efficiency of the motor, and not only the torque caused by the magnet but also the torque caused by the reluctance can be generated, so that the generated torque can be reduced as a whole without increasing the motor current. Brushless DC motors with an embedded magnet structure that can be made larger have been used.

  In order to effectively utilize this reluctance torque, advance angle control is performed to advance the voltage phase of the inverter with respect to the phase of the motor induced voltage. Further, the advance control can effectively utilize the magnetic flux effect and increase the output torque.

  In compressors and the like, a sensorless inverter control device that detects the rotor magnetic pole position from the induced voltage generated in the stator winding without using a sensor such as a hall element is used from the viewpoint of use environment, reliability, and maintenance. Yes.

  In this case, the rotor magnetic pole position is often obtained by using an electrical angle of 60 degrees during the non-control period and observing the induced voltage appearing at the motor terminal during the OFF period of the upper and lower arm switches.

  Hereinafter, the inverter control device will be described with reference to the drawings.

  FIG. 5 is a block diagram showing the configuration of a conventional inverter control device. FIG. 6 is a characteristic diagram showing a load torque-rotational speed characteristic of a conventional inverter control device, and shows a characteristic when wide angle control is performed.

  FIG. 7 is a timing chart showing signal waveforms and processing contents of each part of the conventional inverter control device, and shows characteristics at a wide angle of 150 degrees.

  In FIG. 5, three pairs of switching transistors Tru, Trx, Trv, Try, Trw, and Trz are connected in series between terminals of a DC power supply 001 to constitute an inverter circuit unit 002. The brushless DC motor 003 includes a stator 003a having a 4-pole distributed winding structure and a rotor 003b. The rotor 003b has a magnet embedded structure in which permanent magnets 003α and 003β are embedded.

  A connection point between each pair of switching transistors is connected to terminals of stator windings 003u, 003v, and 003w of Y-connected phases of the brushless DC motor 003, respectively.

  The connection point between each pair of switching transistors is also connected to Y-connected resistors 004u, 004v, and 004w.

  Incidentally, protective reflux diodes Du, Dx, Dv, Dy, Dw, Dz are respectively connected between collector-emitter terminals of the switching transistors Tru, Trx, Trv, Try, Trw, Trz.

  The magnetic pole position detection circuit 010 includes a differential amplifier 011, an integrator 012, and a zero cross comparator 013. The voltage of the neutral point 003d of the Y-connected stator windings 003u, 003v, 003w is supplied to the inverting input terminal of the amplifier 011b via the resistor 011a, and the Y-connected resistors 004u, 004v, 004w The voltage at the neutral point 004d is supplied to the non-inverting input terminal of the amplifier 011b as it is.

  The resistor 011b is connected between the output terminal and the inverting input terminal of the amplifier 011b so as to operate as the differential amplifier 011.

  The output signal output from the output terminal of the differential amplifier 011 is supplied to an integrator 012 formed by connecting a resistor 012a and a capacitor 012b in series.

  The output signal from the integrator 012 (the voltage at the connection point between the resistor 012a and the capacitor 012b) is supplied to the non-inverting input terminal of the zero-cross comparator 013, and the voltage at the neutral point 003d is applied to the inverting input terminal of the zero-cross comparator 013. Is supplied.

  A magnetic pole position detection signal is output from the output terminal of the zero cross comparator 013.

  The differential amplifier 011, the integrator 012, and the zero cross comparator 013 constitute a magnetic pole position detection circuit 010 that detects the magnetic pole position of the rotor 003 b of the brushless DC motor 003.

  The magnetic pole position detection signal output from the magnetic pole position detection circuit 010 is supplied to the microprocessor 020, and the magnetic pole position detection signal supplied to the microprocessor 020 is used for period measurement, phase correction for setting an advance angle and a conduction angle, and the like. To calculate a timer value per electrical angle cycle, and determine the commutation signals of the switching transistors Tru, Trx, Trv, Try, Trw, Trz.

  Further, the microprocessor 020 outputs a voltage command based on the rotation speed command. The microprocessor 020 modulates the voltage command with PWM (Pulse Width Modulation), and controls the duty amount, which is the ON / OFF ratio of the PWM modulation signal, based on the deviation between the rotation speed command and the actual rotation speed. Output modulation signal.

  Then, with respect to the rotational speed command, the duty is increased when the actual rotational speed is low, and conversely, the duty is decreased when the actual rotational speed is high.

  This PWM modulation signal is supplied to the drive circuit 030, and the drive circuit 030 outputs drive signals to be supplied to the respective base terminals of the switching transistors Tru, Trx, Trv, Try, Trw, and Trz.

  About the above inverter control apparatus, the operation | movement of electricity supply is demonstrated.

  In FIG. 7, (A), (B), and (C) are the induced voltages Eu, Ev, and Ew of the U-phase, V-phase, and W-phase of the brushless DC motor 003, and the phases are shifted by 120 degrees. It changes with.

  (D) is a signal output from the differential amplifier 011, and (E) is an integrated waveform by the integrator 012. By supplying this integrated waveform to the zero cross comparator 013, the excitation switching signal rising and falling at the zero cross point of the integrated waveform is output as a magnetic pole position detection signal as shown in (F).

  The inverter mode (N), which is a commutation pattern, is set in one step by the phase correction timer (G1) that starts when the excitation signal rises and falls, and the second phase correction timer (G2) that starts with the phase correction timer. Proceed.

  Here, the U-phase energization timing is calculated from the W-phase induced voltage waveform, and the phase advance amount of the inverter can be controlled by the phase correction timer (G1). In FIG. 7, the energization angle is 150 degrees and the advance angle is 60 degrees. Therefore, the value of the phase correction timer (G1) is equivalent to 45 degrees, and the value of the second phase correction timer is equivalent to 30 degrees.

  As a result, the ON / OFF states of the switching transistors Tru, Trx, Trv, Try, Trw, Trz corresponding to each inverter mode are (H), (I), (J), (K), (L), respectively. , (M).

  As described above, the brushless DC motor 003 can be driven in a state where the energization period is set to 120 degrees to 180 degrees, and the phase of the inverter voltage can be advanced from the motor induced voltage. .

  However, in the above conventional configuration, by detecting the induced voltage generated in the stator windings 003u, 003v, and 003w based on the rotation of the rotor 003b, the induced voltage is phase-shifted by the integrator 012 having a delay of 90 degrees. A position detection signal corresponding to the magnetic pole of the rotor 003b is obtained, and the energization timing to the stator windings 003u, 003v, 003w is determined based on this position detection signal.

  As a result, since the integrator 012 having a 90-degree delayed phase is used, there is a problem that the response to rapid acceleration / deceleration is poor.

  Thus, a position detection circuit with improved responsiveness has been proposed (see, for example, Patent Document 2).

  Hereinafter, a conventional inverter control device described in Patent Document 2 will be described with reference to the drawings.

  FIG. 8 is a block diagram showing the configuration of the inverter control device of Conventional Example 2, and FIG. 9 is a timing chart showing signal waveforms and processing contents of each part of the inverter control device.

  In FIG. 8, resistors 101 and 102 are connected in series between the buses 103 and 104, and a detection terminal ON as a common connection point is a neutral point of the stator windings 105 u, 105 v, and 105 w of the brushless DC motor 105. A voltage VN at a virtual neutral point that is ½ of the voltage of the DC power supply 001 corresponding to the voltage of V is output.

  The comparators 106a, 106b, and 106c have their non-inverting input terminals (+) connected to output terminals OU, OV, and OW through resistors 107, 108, and 109, respectively, and the inverting input terminals (−) are detected. Connected to terminal ON.

  The output terminals of these comparators 106a, 106b and 106c are connected to input terminals I1, I2 and I3 of the microprocessor 110 which is a logic means. The output terminals O1 to O6 drive the transistors Tru, Trx, Trv, Try, Trw, Trz via the drive circuit 120.

  The brushless DC motor 105 has a quadrupole distributed winding structure, and the rotor 105a has a surface magnet structure in which permanent magnets 105α and 105β are arranged on the rotor surface. Accordingly, the conduction angle is set to 120 degrees and the advance angle is set to 0 degrees.

  Next, a description will be given with reference to FIG.

  (A), (B), and (C) show the terminal voltages Vu, Vv, and Vw of the stator windings 105u, 105v, and 105w during steady operation.

  These terminal voltages include supply voltages Vua, Vva, Vwa by the inverter circuit unit 140, induced voltages Vub, Vvb, Vwb generated in the stator windings 105u, 105v, 105w, and a diode of the inverter circuit unit 140 when switching commutation. It becomes a composite waveform with pulse-like spike voltages Vuc, Vvc, Vwc generated when any one of Du, Dx, Dv, Dy, Dw, Dz becomes conductive.

  The terminal voltages Vu, Vv, and Vw, the virtual neutral point voltage VN that is ½ of the DC power supply voltage 001, and the output signals PSu, PSv, and PSw compared by the comparators 106a, 106b, and 106c are (D). , (E), (F).

  In this case, the output signals PSu, PSv, PSw of the comparator are the signals PSua, PSva, PSwa representing the positive and negative and the phases of the induced voltages Vub, Vvb, Vwb, and the pulse voltages Vuc, Vvc, Vwc. Signal PSsub, PSvb, PSwb.

  Since the pulse voltages Vuc, Vvc, and Vwc are ignored by the wait timer, the comparator output signals PSu, PSv, and PSw show the positive and negative and the phase of the induced voltages Vub, Vvb, and Vwb as a result. It will be a thing.

  The microprocessor 110 recognizes the six modes A to F as shown in (G) based on the states of the output signals PSu, PSv, and PSw of each comparator, and from the time when the levels of the output signals PSu, PSv, and PSw change. DSz (O) is output from the drive signal DSu (J) with a delay of 30 degrees in electrical angle.

  Each time T (H) in modes A to F indicates an electrical angle of 60 degrees, and half time (I) of A to F, that is, T / 2 is a delay time corresponding to 30 degrees in electrical angle. It is shown.

  As described above, the position state of the rotor 105a is detected from the induced voltage generated in the stator windings 105u, 105v, and 105w according to the rotation of the rotor 105a of the brushless DC motor 105, and the change time (T) of the induced voltage is determined. The drive signal for energizing each phase stator winding 105u, 105v, 105w is determined and executed according to the detected energization mode and timing to the stator windings 105u, 105v, 105w.

  Therefore, unlike the conventional inverter control device described in Patent Document 1, since a filter circuit is not required, the detection sensitivity of the induced voltage is increased and the starting characteristics can be improved, thereby enabling low-speed driving. Yes.

  Furthermore, since a 90 degree delay characteristic filter circuit is not used and control can be performed with a 30 degree delay by the combination of the first timer 122 and the second timer 123, the responsiveness to rapid acceleration / deceleration is improved.

  Further, the step-out characteristics of the voltage and conduction angle of the inverter control device will be described with reference to FIG.

  FIG. 10 is a characteristic diagram showing the relationship between the voltage of the conventional inverter control device and the step-out characteristic of the conduction angle.

FIG. 10 shows that when the voltage is rapidly decreased, the step-out resistance is lower as the energization angle is larger. Similar characteristics are exhibited when the voltage rises rapidly.
International Publication No. 95/27328 Pamphlet Japanese Patent Laid-Open No. 1-8890

  However, in the conventional configuration described in Patent Document 1, a magnetic pole position detection circuit 010 capable of detecting a position in an electrical angle 180 degree section is proposed, but since a filter is used, an electrical angle of 90 degrees is proposed. There is a problem that a delay occurs, the responsiveness to a rotational fluctuation such as a sudden load fluctuation is poor, and the stepping out stops.

  In addition, in the conventional configuration described in Patent Document 2, a position detection circuit that does not cause a delay of 90 degrees in electrical angle has been proposed. However, wide-angle control that extends a conduction angle to 120 degrees or more is performed, motor induction is performed. When the advance voltage control for advancing the voltage phase of the inverter with respect to the voltage phase is performed or the spike voltage width is increased by increasing the number of turns of the stator windings 105u, 105v, 105w and increasing the inductance for higher efficiency. The section in which the position can be detected is narrowed, and there is a problem that the position cannot be detected due to a rotational fluctuation such as a sudden load fluctuation and the step is lost.

  Further, in a motor using a concentrated winding stator for higher efficiency and higher output torque, when the number of poles of the brushless DC motor 105 is 6, the position detectable section is 2 in mechanical angle compared to the case of 4 poles. Decrease to 3/3.

  Therefore, wide-angle control, advance angle control, and increase in the number of motor turns that narrow the position detectable section, and increase in the number of poles that narrow the mechanical position detectable section narrow the position detection section. When a load fluctuation, a momentary power interruption, or a voltage fluctuation accompanied with a rapid rotation fluctuation occurs, there is a problem that the position cannot be detected and the step-out is stopped.

  The present invention solves the above-mentioned conventional problems, and prevents the step-out stop for instantaneous power failure or sudden voltage fluctuation by changing the conduction angle instantaneously according to the voltage of the DC voltage unit. A highly reliable inverter control device is provided.

  In order to solve the above-described problems, an inverter control device according to the present invention includes an inverter circuit unit that drives a brushless DC motor having a permanent magnet provided on the rotor, and a position detection circuit that detects the relative position of the rotor based on the induced voltage of the brushless DC motor. Unit, a DC voltage detection unit for detecting the voltage value of the DC power supply voltage supplied to the inverter circuit unit, and the conduction angle in the inverter circuit unit according to the voltage value detected by the DC voltage detection unit is 180 degrees in electrical angle And an energization angle controller that changes within a range of less than.

  As a result, by changing the energization angle instantaneously according to the voltage of the DC voltage section, when the rotation speed fluctuates due to a sudden voltage change such as a momentary power interruption, the position detection interval is reduced by reducing the energization angle. And the rotor magnetic pole position is not lost.

  The inverter control device of the present invention can improve the responsiveness to fluctuations in the rotational speed due to voltage changes, and when the rotational speed fluctuates due to sudden voltage changes such as momentary power interruption, The detection interval can be expanded, the rotor magnetic pole position is not lost, step-out due to voltage fluctuation can be prevented, and the instantaneous power failure tolerance can be improved.

  The invention according to claim 1 is an inverter circuit unit that drives a brushless DC motor having a permanent magnet provided on a rotor, a position detection circuit unit that detects a relative position of the rotor by an induced voltage of the brushless DC motor, A DC voltage detection unit for detecting a voltage value of a DC power supply voltage supplied to the inverter circuit unit, and a conduction angle in the inverter circuit unit of less than 180 degrees in electrical angle according to the voltage value detected by the DC voltage detection unit The energization angle control unit that changes within the range of is provided, so that when the rotational speed fluctuates greatly due to a sudden voltage change, the energization angle can be reduced and the position detection section can be expanded. It is possible to prevent step-out due to voltage fluctuation.

  A second aspect of the present invention includes a reference voltage setting unit that sets a reference voltage with respect to a direct current power supply voltage in the first aspect of the invention, and the conduction angle control unit has a voltage value of the direct current power supply voltage. When the voltage becomes lower than the reference voltage, the energization angle in the inverter circuit section is reduced. When the rotational speed is greatly reduced due to a sudden voltage drop, the energization angle is reduced and the position detection section is expanded. Therefore, the rotor magnetic pole position is not lost, and the step-out due to the voltage drop can be prevented.

  The invention according to claim 3 is the invention according to claim 1, further comprising a reference voltage setting unit that sets a reference voltage with respect to the DC power supply voltage, and the conduction angle control unit has a voltage value of the DC power supply voltage that is When the voltage becomes higher than the reference voltage, the conduction angle in the inverter circuit is reduced. When the rotational speed rises rapidly against a sudden voltage rise, the conduction angle is reduced and the position detection section is expanded. This makes it possible to prevent the rotor magnetic pole position from being lost, and to prevent a step-out with respect to rotational fluctuation due to voltage increase.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, further comprising: a reference voltage setting unit that sets a range of a reference voltage value with respect to the DC power supply voltage; and a delay timer. The control unit is characterized in that when the voltage value of the DC power supply voltage changes from outside the range of the reference voltage value to within the range, the conduction angle in the inverter circuit unit is gradually returned to the reference value by the delay timer. In contrast to the fact that the energization angle is reduced with respect to a sudden voltage change, the energization angle can also be restored when the voltage is restored, and it is possible to operate again at high rotation and high torque.

  According to a fifth aspect of the present invention, in the first aspect of the invention, the energization angle control unit reduces the energization angle in the inverter circuit unit when the DC power supply voltage decreases at a rate of change of 300 V / sec or more. Therefore, even with a sudden voltage drop such as a momentary power failure, it is possible to improve the momentary power tolerance by expanding the position detection section.

  The invention according to claim 6 is applied to the invention according to any one of claims 1 to 5, wherein the rotor of the brushless DC motor has a permanent magnet embedded therein and has saliency. In addition, it is possible to prevent step-out due to voltage fluctuations and to improve the instantaneous power failure tolerance even for those that perform advance angle control that effectively utilizes the reluctance torque to narrow the position detection section.

  The invention according to claim 7 is applied to the invention according to any one of claims 1 to 6, wherein the number of windings of the stator winding of the brushless DC motor is 160 turns or more, and the inductance is Even for a motor that is large and has a spike voltage width that narrows the position detection section, step-out due to voltage fluctuation can be prevented, and the instantaneous power failure tolerance can be improved.

  The invention according to an eighth aspect is the invention according to any one of the first to seventh aspects, wherein the brushless DC motor is applied to one having six or more poles, and mechanically due to an increase in the number of poles. A step-out due to voltage fluctuation can be prevented even for a motor whose position detection section is narrowed by an angle, and the instantaneous power failure tolerance can be improved.

  The invention according to claim 9 is the one in which the inverter control device according to any one of claims 1 to 8 is applied to an electric compressor, and can prevent step-out due to voltage fluctuation, The instantaneous power failure tolerance can be improved, and a highly reliable electric compressor can be provided.

  Invention of Claim 10 applies the inverter control apparatus of the invention as described in any one of Claim 1 to 8 to household electric appliances, such as a refrigerator, and has the tolerance with respect to a voltage fluctuation or a momentary power failure. It can be improved and a highly reliable household electric appliance such as a refrigerator can be provided.

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

(Embodiment 1)
FIG. 1 is a block diagram of an inverter control apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a timing chart showing signal waveforms and processing contents of respective parts in the same embodiment. FIG. 3 is a characteristic diagram showing the relationship between the change in power supply voltage and the conduction angle in the same embodiment. FIG. 4 is a characteristic diagram showing an operation at the momentary power failure of the inverter control device according to the embodiment.

  In FIG. 1, an inverter control device 200 is connected to a commercial AC power source 201 and an electric compressor (not shown), a rectifying unit 203 that converts the commercial AC power source 201 into a DC power source, and a brushless DC of the electric compressor. An inverter circuit unit 205 for driving the motor 204 is provided.

  Further, a drive circuit 206 for driving the inverter circuit unit 205, a position detection circuit unit 207 for detecting the magnetic pole position of the brushless DC motor 204, a microprocessor 208 for controlling the inverter circuit unit 205, and a rectification unit 203 converted to a DC power source. DC voltage detector 209 for detecting the voltage of

  The DC voltage detection unit 209 is configured by a voltage dividing circuit using a resistor, and is input to the microprocessor 208 as an analog value. Also, a CR filter circuit for noise removal is provided.

  The microprocessor 208 includes a rotation speed detection unit 210, a commutation control unit 211, a duty setting unit 212, a PWM control unit 213, a drive control unit 214, and a carrier output unit 215.

  Furthermore, a reference voltage setting unit 217 that determines a plurality of reference voltages with respect to the DC power supply voltage, and a conduction angle control unit 218 that determines a conduction angle with respect to each reference voltage are provided. The conduction angle control unit 218 is provided with a delay timer 218a.

  The brushless DC motor 204 is a 6-pole salient pole concentrated winding motor, and includes a three-phase winding stator 204a and a rotor 204b.

  The stator 204a has a 6-pole 9-slot structure, and the number of turns of each phase of the stator windings 204u, 204v, 204w is 189 turns. The rotor 204b is a magnet-embedded structure in which permanent magnets 204α, 204β, 204γ, 204δ, 204ε, and 204ζ are arranged to generate reluctance torque.

  The inverter circuit unit 205 is composed of 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 each of them. It is configured.

  The position detection circuit unit 207 includes a comparator (not shown) and the like, and a terminal voltage signal based on the induced voltage of the brushless DC motor 204 and a reference voltage are compared by a comparator to obtain a position signal of the rotor 204b. . The configuration is the same as in Conventional Example 2.

  The commutation control unit 211 calculates the commutation timing from the position signal of the position detection circuit unit 207 and generates commutation signals of the switching transistors Tru, Trx, Trv, Try, Trw, and Trz.

  The rotation speed detection unit 210 calculates the rotation speed of the brushless DC motor 204 by counting the position signal from the position detection circuit unit 207 for a certain period or measuring the pulse interval.

  The duty setting means 212 performs a duty addition / subtraction operation based on the deviation between the rotational speed obtained from the rotational speed detection means 210 and the command rotational speed, and outputs the duty value to the PWM control means 213. When the actual rotational speed is low with respect to the rotational speed command, the duty is increased. Conversely, when the actual rotational speed is high, the duty is decreased.

  The carrier output means 215 sets a carrier frequency for switching the switching transistors Tru, Trx, Trv, Try, Trw, Trz. In this case, the carrier frequency is set between 3 kHz and 10 kHz.

  The PWM control unit 213 outputs a PWM modulation signal from the carrier frequency set by the carrier output unit 215 and the duty value set by the duty setting unit 212.

  The reference voltage setting unit 217 sets a plurality of reference voltages and sets a plurality of reference voltage ranges. Then, the conduction angle control unit 218 controls the conduction angle in the inverter circuit unit 205 based on the DC voltage detected by the DC voltage detection unit 209 and the plurality of reference voltages and the reference voltage range.

  The drive control means 214 synthesizes the commutation signal, the PWM modulation signal, the energization angle, and the advance angle to generate a drive signal for turning on / off the switching transistors Tru, Trx, Trv, Try, Trw, Trz, and a drive circuit. It outputs to 206. The drive circuit 206 performs ON / OFF switching of the switching transistors Tru, Trx, Trv, Try, Trw, and Trz based on the drive signal, and drives the brushless DC motor 204.

  Next, various waveforms of the inverter control device shown in FIG. 2 will be described.

  The inverter control device 200 controls the brushless DC motor 204 with a conduction angle of 150 degrees and an advance angle of 15 degrees.

  (A), (B), and (C) are terminal voltages Vu, Vv, and Vw of the U-phase, V-phase, and W-phase of the brushless DC motor 204, and change in a state where the respective phases are shifted by 120 degrees. .

  These terminal voltages include supply voltages Vua, Vva, Vwa by the inverter circuit unit 205, induced voltages Vub, Vvb, Vwb generated in the stator windings 204u, 204v, 204w, and a free-wheeling diode of the inverter circuit 205 when the commutation is switched. It becomes a composite waveform with pulse-like spike voltages Vuc, Vvc, Vwc generated when any one of Du, Dx, Dv, Dy, Dw, Dz becomes conductive.

  Then, these terminal voltages Vu, Vv, and Vw are compared with a virtual neutral point voltage VN that is ½ of the DC power supply voltage 1, and the output signals PSu, PSv, and PSw are output from the comparators to (D), (E ), (F).

  Here, when the DC power supply voltage rapidly decreases, the actual rotation speed decreases, and the cross point at which the induced voltage is inverted compared to the virtual neutral point voltage VN disappears into the energization interval. Further, when the DC power supply voltage rises rapidly, the cross point disappears into the spike voltage. Either of these results in false detection and step-out.

  Therefore, in the present embodiment, as shown in FIG. 3, a plurality of reference voltages Edn1, Edn2, Edn3, Edn4, Eup1, Eup2, Eup3, and Eup4 are provided for the DC power supply voltage, and the energization angle for each reference voltage is provided. Is to determine.

  If the DC power supply voltage is suddenly decreased when the DC power supply voltage is normally decreased, the energization angle is instantaneously changed from 150 degrees to 142.5 degrees when Edn1 is detected. Similarly, when Edn2 is detected, the angle is instantly changed from 142.5 degrees to 135 degrees. Similarly, the conduction angle is decreased from 135 degrees to 127.5 degrees and 120 degrees.

  In this way, the position detection interval can be increased by narrowing the energization angle along with the decrease in the DC power supply voltage, preventing the induced voltage from being delayed and hiding the cross point in the energization area, and misdetecting position detection. Can be prevented from stepping out.

  Similarly, when the DC power supply voltage suddenly rises, when Eup1 is exceeded, the conduction angle is changed from 150 degrees to 142.5 degrees, and every time the DC power supply voltage exceeds the reference voltages Eup2, Eup3, Eup4, The conduction angle is narrowed from 142.5 degrees to 135 degrees, 127.5 degrees, and 120 degrees.

  Thereby, the spike voltage width can also be reduced, and the position detectable section can be enlarged, so that step-out due to erroneous detection of position detection can be prevented.

  Next, the operation at the momentary power failure will be described with reference to FIG.

  When the DC power supply voltage enters the range of Esw1 from the outside of the reference voltage range Esw1, the conduction angle is gradually returned to the reference value of 150 degrees.

  At this time, assuming that the delay timer 218a is set to 100 ms, the delay timer 218a returns from 120 degrees to 127.5 degrees after 100 ms after entering the range of Esw1. Further, after 100 ms, it returns from 127.5 degrees to 135 degrees, and finally returns to the reference value of 150 degrees after 400 ms. If there is a voltage change during the return, the control for instantly narrowing the energization angle is performed as described above.

  In this embodiment, the energization angle is changed from 150 degrees to 120 degrees in five steps. However, the DC power supply voltage and the energization angle may be changed linearly or may be changed suddenly from 150 degrees to 120 degrees. May be. Furthermore, by using an energization angle of less than 120 degrees, a system that can withstand fluctuations in power supply voltage and instantaneous power failure can be obtained.

  In addition, even if the inverter control device 200 is used for an electric compressor, good operation is possible, and even if the inverter control device 200 is used for household electric equipment such as a refrigerator, good system operation is possible.

  As described above, since the inverter control device according to the present invention can detect the position without losing sight of the rotor magnetic pole with respect to the power supply voltage fluctuation, household electric equipment such as an air conditioner, a refrigerator, a washing machine, etc. Useful for electric vehicles. It is also useful in areas where power supply voltage fluctuates frequently.

Block diagram of the inverter control apparatus in Embodiment 1 of the present invention Timing chart showing signal waveforms and processing contents of each part in the same embodiment Characteristic diagram showing the relationship between the change in power supply voltage and the conduction angle in the same embodiment The characteristic figure which shows the operation | movement at the time of a momentary power failure of the inverter control apparatus in the same embodiment Configuration diagram showing the configuration of a conventional inverter control device Characteristic diagram showing load torque-rotational speed characteristics of a conventional inverter control device Timing chart showing signal waveforms and processing contents of each part of conventional inverter control device Configuration diagram showing the configuration of a conventional inverter control device Timing chart showing signal waveforms and processing contents of each part of conventional inverter control device A characteristic diagram showing the relationship between the voltage of the conventional inverter control device and the step-out characteristic of the conduction angle

Explanation of symbols

200 Inverter control device 204 Brushless DC motor 204b Rotor 204α, 204β, 204γ, 204δ, 204ε, 204ζ Permanent magnet 204u, 204v, 204w Stator winding 205 Inverter circuit unit 207 Position detection circuit unit 209 DC voltage detection unit 217 Reference voltage setting unit 218 Energization angle controller 218a Delay timer

Claims (10)

  An inverter circuit section for driving a brushless DC motor having a permanent magnet provided on the rotor, a position detection circuit section for detecting the relative position of the rotor based on an induced voltage of the brushless DC motor, and a DC power source supplied to the inverter circuit section A direct current voltage detection unit for detecting a voltage value of the voltage, and a conduction angle control unit for changing the conduction angle in the inverter circuit unit within an electrical angle of less than 180 degrees according to the voltage value detected by the direct current voltage detection unit And inverter control device.   A reference voltage setting unit for setting a reference voltage with respect to the DC power supply voltage is provided, and the conduction angle control unit reduces the conduction angle in the inverter circuit unit when the voltage value of the DC power supply voltage becomes smaller than the reference voltage. The inverter control device according to claim 1.   A reference voltage setting unit for setting a reference voltage with respect to the DC power supply voltage is provided, and the energization angle control unit reduces the energization angle in the inverter circuit unit when the voltage value of the DC power supply voltage becomes larger than the reference voltage. The inverter control device according to claim 1.   A reference voltage setting unit for setting a range of a reference voltage value for a DC power supply voltage and a delay timer are provided, and the conduction angle control unit is configured to change the voltage value of the DC power supply voltage from outside the range of the reference voltage value to within the range. The inverter control device according to any one of claims 1 to 3, wherein the conduction angle in the inverter circuit unit is gradually returned to the reference value by a delay timer.   2. The inverter control device according to claim 1, wherein the energization angle control unit reduces the energization angle in the inverter circuit unit when the DC power supply voltage decreases at a rate of change of 300 V / second or more.   6. The inverter control device according to claim 1, wherein the rotor of the brushless DC motor has a saliency with a permanent magnet embedded therein.   The inverter control device according to any one of claims 1 to 6, wherein the number of windings of the stator winding of the brushless DC motor is 160 turns or more.   The inverter control device according to any one of claims 1 to 7, wherein the number of poles of the brushless DC motor is six or more.   The electric compressor using the inverter control apparatus as described in any one of Claim 1 to 8.   Home electric appliances, such as a refrigerator, using the inverter control device according to any one of claims 1 to 8.

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