JP2012105384A - Inverter control device and electric compressor and household electrical equipment using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problems in an inverter control device that when wide angle control for expanding an energization angle to 120 degrees or more or spark advance control for advancing a voltage phase with respect to the phase of an induction voltage induced in a stator of a brushless DC motor is exerted, a non-conduction angle produces 30 degrees of electric angle, causing the inverter to become unable to sufficiently output a desired voltage and have its DC voltage utilization rate dropped slightly, which resulted in that the terminal voltage of the brushless DC motor is slightly reduced and becomes slightly narrower than desired for an operation range.SOLUTION: Control is exerted in such a way that at least once in one cycle of mechanical angle of a brushless DC motor, an energization angle is commutated prior to the zero-cross point of an induction voltage based on a calculated value which is calculated from a detection value acquired in the past, and not using the zero-cross point of an induction voltage detected by position detection means 208. By so doing, a non-conduction angle is restricted to less than 30 degrees of electric angle, making control possible in a wider operation range than ever.

Description

  The present invention relates to an inverter control device mounted on a device that drives a brushless DC motor. In particular, the present invention relates to wide-angle energization control in an inverter control device for a brushless DC motor, and further relates to an electric compressor and household electrical equipment using the inverter control device.

  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 for driving a brushless DC motor, although the electrical angle of each positive and negative is 180 degrees, the switch of each phase of the inverter is made to conduct only by an electrical angle of 120 degrees, and the remaining electrical angle is 60 degrees. 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 rotation speed is reduced.

  Therefore, in Patent Document 1, the energization width of the voltage source inverter is set to a predetermined width greater than 120 degrees and 180 degrees or less 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 and the operating range is widened.

  In recent years, permanent magnets have been embedded inside the rotor to increase the efficiency of the motor, and not only torque caused by magnets but also torque caused by reluctance can be generated without increasing the motor current as a whole. A brushless DC motor having an embedded magnet structure capable of increasing the generated torque has been used.

  In order to effectively use 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 angle control can effectively use the magnetic flux weakening effect and increase the output torque.

  In a motor using a sensor such as a hall element, the rotor magnetic pole position can be accurately recognized by the sensor, so there is no need to detect the rotor magnetic pole position by an indirect induced voltage, and the rotor magnetic pole position can be directly detected from the sensor. Since it can be determined, motor control can be easily performed.

  However, in a hermetic compressor, embedding a sensor such as a Hall element itself is not easy to adopt from the viewpoint of sensor failure due to the use environment, reliability such as refrigerant leakage, and maintenance of the motor in the event of failure due to the sensor integrated type. In general, a sensorless inverter control device that detects the rotor magnetic pole position by an induced voltage generated in the stator winding without using a sensor such as a Hall element is used.

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.

  The conventional inverter control apparatus will be described below with reference to the drawings.

  FIG. 8 is a diagram illustrating a configuration of a conventional inverter control device described in Patent Document 1. In FIG. FIG. 9 is a diagram 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.

  FIG. 10 is a diagram showing load torque and rotational speed characteristics of a conventional inverter control device, and shows characteristics when wide-angle energization control is performed.

  In FIG. 8, three pairs of switching transistors Tru, Trx, Trv, Try, Trw, and Trz are connected in series between terminals of a DC power source 001 to form an inverter circuit unit 002.

  The brushless DC motor 003 includes a stator 003a having a four-pole distributed winding structure and a rotor 003b. The rotor 003b has a magnet embedded structure in which permanent magnets 003α and permanent magnets 003β are embedded.

  The connection point between each pair of switching transistors Tru, Trx, Trv, Try, Trw, Trz is the terminals of the stator winding 003u, stator winding 003v, and stator winding 003w of each phase Y-connected to the brushless DC motor 003. Are connected to each.

  The connection point between each pair of switching transistors Tru, Trx, Trv, Try, Trw, and Trz is also connected to Y-connected resistors 004u, 004v, and 004w, respectively.

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

  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 winding 003u, stator winding 003v, and stator winding 003w is supplied to the inverting input terminal of the amplifier 011b via the resistor 011a, and the Y-connected resistor The voltage at the neutral point 004d of 004u, 004v, and 004w is supplied as it is to the non-inverting input terminal of the amplifier 011b.

  The resistor 011c 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. The inverting input terminal of the zero-cross comparator 013 has a neutral point 003d. Voltage is being 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.

  In the microprocessor 020, based on the magnetic pole position detection signal output from the magnetic pole position detection circuit 010, the period measurement, the phase correction for setting the advance angle and the conduction angle, etc. are performed, and the timer value per cycle of the electrical angle is determined. Calculate and determine the commutation signals of the switching transistors Tru, Trx, Trv, Try, Trw, Trz.

  The microprocessor 020 outputs a voltage command based on the rotation speed command, modulates the voltage command with PWM (pulse width modulation), and turns on / off the PWM modulation signal based on a deviation between the rotation speed command and the actual rotation speed. The duty amount which is the OFF ratio is controlled, and PWM modulation signals for three phases are output.

  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 inverter control apparatus comprised as mentioned above, the operation | movement in the energization is demonstrated below.

  In FIG. 9, (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) that is a commutation pattern is advanced by 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 this phase correction timer. .

  Here, the U-phase energization timing is calculated from the waveform of the W-phase induced voltage Ew, and the phase advance amount of the inverter circuit unit 002 can be controlled by the phase correction timer (G1). In FIG. 9, the energization angle is 150 degrees and the advance angle is 60 degrees. Accordingly, the value of the phase correction timer (G1) is equivalent to 45 degrees, and the value of the second phase correction timer (G2) is equivalent to 30 degrees.

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

  Further, by performing the wide-angle energization control, it is possible to expand the operation region where the load torque is large as shown in FIG.

  However, in the conventional configuration, an induced voltage generated in the stator winding 003u, the stator winding 003v, and the stator winding 003w is detected based on the rotation of the rotor 003b, and this induced voltage is integrated into an integrator having a delay of 90 degrees. The position detection signal corresponding to the magnetic pole of the rotor 003b is obtained by shifting the phase by 012. Based on this position detection signal, the energization timing to the stator winding 003u, the stator winding 003v, and the stator winding 003w is determined. It is the composition to do.

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

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

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

  FIG. 11 is a diagram showing a configuration of another conventional inverter control device, and FIG. 12 is a diagram showing signal waveforms and processing contents of respective parts of another conventional inverter control device.

  In FIG. 11, resistors 101 and 102 are connected in series between buses 103 and 104, and a detection terminal ON as a common connection point is a stator winding 105 u, a stator winding 105 v, a stator winding of a 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 at the neutral point of the line 105w is output.

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

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

  A first timer 122 that measures the change time of the induced voltage is provided based on the output signals of the comparators 106a, 106b, and 106c, and a second timer 123 that obtains a delay time based on the change time measured by the first timer 122 is provided. Is provided.

  Drive for energizing the stator winding 105u, the stator winding 105v, and the stator winding 105w of each phase from the positive and negative states of the induced voltage based on the output signals of the comparators 106a, 106b, and 106c and the timing of the second timer 123 Output a signal.

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

  About the inverter control apparatus comprised as mentioned above, the operation | movement is demonstrated below.

  In FIG. 12, (A), (B), and (C) show terminal voltages Vu, Vv, and Vw of the stator winding 105u, the stator winding 105v, and the stator winding 105w during the steady operation.

  These terminal voltages Vu, Vv, and Vw are supplied voltages Vua, Vva, and Vwa from the inverter circuit unit 140, and induced voltages Vub, Vvb, and Vwb that are generated in the stator winding 105u, the stator winding 105v, and the stator winding 105w, respectively. When the commutation is switched, a combined waveform with the pulsed spike voltages Vuc, Vvc, and Vwc generated when any of the free-wheeling diodes Du, Dx, Dv, Dy, Dw, and Dz of the inverter circuit unit 140 becomes conductive. .

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

  In this case, the output signals PSu, PSv, PSw of the comparators 106a, 106b, 106c are the signals PSua, PSva, PSwa representing the positive and negative and the phases of the aforementioned induced voltages Vub, Vvb, Vwb, and the pulse-like voltage described above. It consists of signals PSub, PSvb, PSwb corresponding to spike voltages Vuc, Vvc, Vwc.

  Further, since the spike voltages Vuc, Vvc, and Vwc of the pulse voltage are ignored by the wait timer, the output signals PSu, PSv, and PSw of the comparators 106a, 106b, and 106c result in the induced voltages Vub, Vvb, and Vwb. Positive, negative, and phase are indicated.

  The microprocessor 110 recognizes six modes A to F as shown in (G) based on the states of the output signals PSu, PSv, and PSw of the comparators 106a, 106b, and 106c. The state in which the drive signals DSu, DSv, DSw, DSx, DSy, DSz are output after being delayed by an electrical angle of 30 degrees from the time when the levels of the output signals PSu, PSv, PSw are changed from (J) to ( O).

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

  Thus, the position state of the rotor 105a is detected from the induced voltages Vub, Vvb, Vwb generated in the stator winding 105u, the stator winding 105v, and the stator winding 105w according to the rotation of the rotor 105a of the brushless DC motor 105. Then, the change times (T) of the induced voltages Vub, Vvb, Vwb are detected, and the stator windings 105u, stator windings of each phase are determined according to the energization mode and timing of the stator winding 105u, the stator winding 105v, the stator winding 105w. A drive signal for energizing the line 105v and the stator winding 105w is determined and executed.

  Therefore, unlike the conventional inverter control device described in Patent Document 1, since no filter circuit is required, the detection sensitivity of the induced voltages Vub, Vvb, Vwb is increased, and the starting characteristics can be improved. Low speed drive is possible.

  Furthermore, since a filter circuit having a 90-degree delay characteristic 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 response to sudden acceleration / deceleration is improved.

International Publication No. 95/27328 Japanese Patent Laid-Open No. 1-8890

  However, in the conventional configuration described in Patent Document 1 and Patent Document 2, an inverter circuit is provided for wide-angle control that widens the conduction angle to 120 degrees or more, and for the phase of the induced voltage induced in the stator of the brushless DC motor. Although the advance angle control for advancing the voltage phase of the unit 140 is performed, the conduction angle at which the position of the induced voltage can be detected is at most 150 degrees in the section where the conduction angle is less than 180 degrees, and the remaining section of the electrical angle is 30 degrees. It becomes a non-energized angle, and the desired voltage cannot be output sufficiently from the inverter, and the DC voltage utilization rate of the inverter slightly decreases, so the terminal voltage of the brushless DC motor also decreases slightly, and the desired value corresponding to the operating range However, it has a problem of being slightly narrower.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object of the present invention is to provide an inverter control device that performs wide-angle control with a conduction angle of 150 degrees or more and can perform control over a wider operating range.

  In order to solve the above-mentioned problems, the inverter control device of the present invention acquires in the past without using the zero-cross point of the induced voltage detected by the position detection means at least once during one mechanical angle cycle of the brushless DC motor. On the basis of the calculated value calculated from the detected value, control is performed to commutate the energization angle before the zero cross point of the induced voltage.

  As a result, wide angle control can be performed at an energization angle of 150 degrees or more, the torque of the inverter can be increased, and an inverter control device that can be controlled in a wider operating range can be provided.

  The inverter control device according to the present invention controls the commutation of the conduction angle calculated from the detection value acquired in the past by the position detection means in the brushless DC motor drive before the zero cross point of the induced voltage. Wide-angle control can be performed at an energization angle of more than 15 degrees, and control can be performed over a wider operating range. As a result, it is possible to provide an inverter control device having equivalent performance using a smaller motor than the conventional one. In addition, the use of a small motor can reduce the cost and the size of the unit.

The block diagram of the inverter control apparatus in embodiment of this invention Signal waveform diagram of conduction angle of 150 degrees or less of inverter control device in embodiment of present invention The flowchart of the inverter control of the inverter control apparatus in embodiment of this invention Flowchart of conduction angle of 150 degrees or less of inverter control apparatus in embodiment of the present invention The flowchart above the conduction angle of 150 degrees of the inverter control device in the embodiment of the present invention. Signal waveform diagram above the conduction angle of 150 degrees of the inverter control device in the embodiment of the present invention Flowchart of wide-angle control of inverter control apparatus in embodiment of the present invention The figure which shows the structure of the conventional inverter control device The figure which shows the signal waveform and processing content of each part of the conventional inverter control apparatus The figure which shows the load torque and rotational speed characteristic of the conventional inverter control device The figure which shows the structure of the other conventional inverter control apparatus The figure which shows the signal waveform of each part of other conventional inverter control apparatuses, and the processing content

  1st invention detects the relative position with respect to the said stator of the inverter circuit part which drives the brushless DC motor which provided the permanent magnet in the rotor, and the induced voltage induced in the stator of the said brushless DC motor And a conduction angle control means for controlling a conduction angle of the inverter circuit unit. The conduction angle control means determines an conduction voltage in the inverter circuit unit based on a detection value of the position detection unit. The inverter is controlled so as to commutate before the zero cross point, and the inverter circuit unit does not use a sensor such as a Hall element.

  As a result, in the section where the conduction angle is less than 180 degrees, the normal maximum angle of 150 degrees of the conduction angle at which the position of the induced voltage can be detected can be set to 150 degrees or more. Torque can be increased and control can be performed in a wider operating range.

  In a second aspect of the invention, in particular, in the first aspect of the invention, the output of the conduction angle control means is a zero cross point of the induced voltage detected by the position detection means at least once during one mechanical angle cycle of the brushless DC motor. It is calculated from detection values acquired in the past without being used, and the conduction angle in the inverter circuit unit is commutated before the zero cross point of the induced voltage.

  Thus, simultaneously with the control by the induced voltage detected by the position detecting means, the energization angle obtained by the calculation of the output of the energization angle control means can be set to 150 degrees or more, and by reducing the non-energization angle, the inverter Torque can be increased, and control can be performed in a wider operating range.

  In particular, the third invention has a duty setting means in the first or second invention, and the energization angle control means is configured such that when the energization rate to the brushless DC motor is equal to or greater than a predetermined duty, Based on the detection value of the position detection means, control is performed to commutate the conduction angle in the inverter circuit section before the zero cross point of the induced voltage.

  As a result, the applied torque can be increased only in the control range that cannot be driven by the conventional wide angle control, and motor control with increased practicality can be performed.

  In a fourth aspect of the present invention, in particular, in any one of the first to third aspects of the brushless DC motor according to any one of the first to third aspects, the conduction angle control unit may be calculated based on a time interval of a zero cross point of an induced voltage detected by the position detection unit. When the rotational speed is equal to or higher than a predetermined rotational speed, control is performed to commutate the energization angle in the inverter circuit section before the zero cross point of the induced voltage based on the detection value of the position detection means. It is.

  Thus, only when the driving torque is increased, the applied torque can be increased, and motor control with increased practicality can be performed.

  According to a fifth aspect of the invention, in particular, the brushless DC motor rotor according to any one of the first to fourth aspects of the invention has a configuration in which a permanent magnet is embedded therein and has saliency.

  As a result, by performing wide-angle control with a conduction angle of 150 degrees or more, it is possible to perform control that is advanced from the zero-cross point of the induced voltage of the brushless DC motor, and an inverter control device that utilizes reluctance torque more effectively. Can be provided.

  The sixth aspect of the invention is particularly an electric compressor using the inverter control device of any one of the first to fifth aspects of the invention. Even when applied to an electric compressor, the motor control of a higher load is performed. An electric compressor that can be performed and can be controlled in a wider operating range can be provided.

  The seventh aspect of the invention is a household electric appliance that uses the inverter control device according to any one of the first to fifth aspects of the invention, and is more widely operated when applied to a household electric appliance such as a refrigerator. A range of motor control can be performed, and an electric appliance for home use such as an easy-to-use refrigerator can be provided.

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

(Embodiment 1)
FIG. 1 is a block diagram of an inverter control device according to the first embodiment of the present invention, and FIG. 2 is a signal waveform diagram of a conduction angle of 150 degrees or less of the inverter control device according to the first embodiment. The contents are shown. FIG. 3 is a flowchart of inverter control of the inverter control device according to the first 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 202 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 204 for driving the motor 203 is provided.

  Furthermore, a drive circuit 205 that drives the inverter circuit unit 204, a position detection circuit unit 206 that detects a terminal voltage of the brushless DC motor 203, and a microprocessor 207 that controls the inverter circuit unit 204 are provided.

  The microprocessor 207 includes a position detection unit 208, an energization angle control unit 209 that determines an energization angle, and a commutation control unit 210 that generates a commutation signal.

  Here, the position detection unit 208 includes a position detection determination unit 208a that detects the magnetic pole position of the brushless DC motor 203 with respect to the output signal from the position detection circuit unit 206, and a position detection standby that determines the start of sampling of the magnetic pole position detection. It is comprised by the means 208b.

  Further, the microprocessor 207 includes a rotation speed detection unit 211 that calculates a rotation speed with respect to an output from the position detection determination unit 208a, and a duty setting unit 212 that performs PWM modulation on the commutation signal according to the rotation speed. And a carrier output means 213, a PWM control means 214, and a drive control means 215 for driving the drive circuit 205 by the outputs of the commutation control means 210 and the PWM control means 214.

  The brushless DC motor 203 is a 6-pole salient pole concentrated winding motor, and includes a three-phase winding stator 203a and a rotor 203b.

  The stator 203a has a 6-pole 9-slot structure, and the number of turns of each phase of the stator winding 203u, the stator winding 203v, and the stator winding 203w is 189 turns. The rotor 203b has a built-in magnet structure in which a permanent magnet 203α, a permanent magnet 203β, a permanent magnet 203γ, a permanent magnet 203δ, a permanent magnet 203ε, and a permanent magnet 203ζ are arranged to generate a reluctance torque.

  The inverter circuit unit 204 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 each of them. It is configured.

  The position detection circuit unit 206 includes a comparator (not shown) and the like, and obtains a position detection signal by comparing a terminal voltage signal based on the induced voltage of the brushless DC motor 203 with a reference voltage using a comparator. .

  The position detection standby unit 208b separates the spike voltage signal from the output signal of the position detection circuit unit 206, and sets a wait time for ignoring the spike voltage signal in order to extract only the position detection signal.

  The position detection determination unit 208a obtains the position signal of the rotor 203b from the output signal of the position detection circuit unit 206, and generates a position detection signal.

  The energization angle control means 209 controls the energization angle in the commutation control means 210 based on the position detection information obtained by the position detection determination means 208a. The energization angle update timer 209a sets the update period of the energization angle by the energization angle control means 209.

  The commutation control means 210 calculates the commutation timing based on the position signal of the position detection determination means 208a and the energization angle of the energization angle control means 209, and commutates the switching transistors Tru, Trx, Trv, Try, Trw, Trz. Generate a signal.

  The rotation speed detection unit 211 calculates the rotation speed of the brushless DC motor 203 by counting the position signal from the position detection determination unit 208a 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 rotation speed obtained from the rotation speed detection means 211 and the command rotation speed, and outputs the duty value to the PWM control means 214. 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.

  The carrier output means 213 sets the 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 214 outputs a PWM modulation signal from the duty value set by the duty setting unit 212 and the carrier frequency set by the carrier output unit 213.

  The drive control means 215 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. Output to 205.

  The drive circuit 205 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 203.

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

  Here, the inverter control device 200 shows a state in which the brushless DC motor 203 is controlled with a conduction angle of 150 degrees and an advance angle of 15 degrees.

  (A), (B), and (C) are the terminal voltages Vu, Vv, and Vw of the U-phase, V-phase, and W-phase of the brushless DC motor 203, and each phase changes in a state shifted by 120 degrees. .

  These terminal voltages are supplied voltages Vua, Vva, Vwa by the inverter circuit unit 204, induced voltages Vub, Vvb, Vwb generated in the stator winding 203u, the stator winding 203v, the stator winding 203w, and the commutation switching. It becomes a composite waveform with pulse-like spike voltages Vuc, Vvc, Vwc generated when any of the free-wheeling diodes Du, Dx, Dv, Dy, Dw, Dz of the inverter circuit unit 204 is turned on.

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

  This output signal includes PSua, PSva, PSwa corresponding to the supply voltages Vua, Vva, Vwa, PSuc, PSvc, PSwc corresponding to the spike voltages Vuc, Vvc, Vwc, the induced voltages Vub, Vvb, Vwb and the virtual neutrality. It becomes a composite signal with PSub, PSvb, PSwb corresponding to the period during the point voltage VN comparison.

  Here, since the pulse-like spike voltages Vuc, Vvc, Vwc are ignored by the wait time (G) set by the position detection standby unit 208b, the comparator output signals PSu, PSv, PSw result in the induced voltage Vub, Vvb, Vwb positive and negative, and phase are shown.

  The microprocessor 207 recognizes six modes A to F as shown in (H) based on the states of the output signals PSu, PSv and PSw of each comparator, and drives according to the states of the output signals PSu, PSv and PSw. DSz (N) is output from the signal DSu (I).

  That is, the elapsed time in each of the modes A to F shown in (H) indicates the occurrence interval of the state change of the position detection signal recognized by the microprocessor 207, that is, the position detection interval (O).

  Next, the detailed operation will be described with reference to the flowchart of FIG.

  In FIG. 3, the position detection standby unit 208 b is from step 103 to step 202. Further, the position detection determination means 208a is from step 202 to step 305.

  First, in step 101, the timer starts counting, and in step 102, it waits until the commutation time elapses. After the commutation time has elapsed, in step 103, drive signals DSu, DSv, DSw, DSx, DSy, DSz are output to the drive circuit 205, and a commutation operation is performed. Details of the commutation operation will be described later with reference to FIGS.

  Here, the position detection determination means 208a and the position detection standby means 208b constituting the position detection means 208 will be described.

  First, the position detection standby unit 208b will be described.

  When the commutation operation is performed, one of the switching transistors Tru, Trx, Trv, Try, Trw, and Trz of the inverter circuit unit 204 is turned on immediately before switching from ON to OFF. The period until the energy stored in the stator winding 203u, stator winding 203v, and stator winding 203w that has been discharged is released by conduction in any of the free-wheeling diodes Du, Dx, Dv, Dy, Dw, and Dz , Pulse-like spike voltages Vuc, Vvc, Vwc are generated.

  After ignoring the spike voltages Vuc, Vvc, and Vvw, the induced voltages Vub, Vvb, and Vwb perform position detection using a cross point that passes through the virtual neutral point voltage VN. That is, the process waits until the wait time elapses in step 104, and after the wait time elapses, position detection is started in step 105.

  That is, the position detection standby unit 208b waits for the start of position detection until the wait time elapses, and performs position detection after ignoring the spike voltages Vuc, Vvc, and Vvw.

  Next, the position detection determination unit 208a will be described.

  In step 106, the states of the output signals PSu, PSv, PSw from the position detection circuit unit 206 are detected. Subsequently, in step 107, the output states of the switching transistors Tru, Trx, Trv, Try, Trw, Trz, that is, The position detection determination is performed according to the state of the output signals PSu, PSv, PSw corresponding to the state of the operation mode in FIG.

  As an example, when the operation mode in FIG. 2 is A, the rising of the U-phase terminal voltage is detected by detecting PSu at H level, PSv at L level, and PSw at H level. Similarly, in other operation mode states, the rising or falling of each terminal voltage with respect to the virtual neutral point voltage VN is detected by examining the states of PSu, PSv, and PSw.

  When the position detection is determined, the process proceeds to step 108.

  Step 108 reads the timer and measures the elapsed time since the previous position detection. Here, since the position detection by the rising or falling detection of each terminal voltage occurs 6 times during one period of the terminal voltage, the elapsed time corresponding to 60 degrees in electrical angle is obtained by measuring the position detection interval. Obtainable.

  Usually, the spike voltages Vuc, Vvc, Vwc end before the cross point where the induced voltages Vub, Vvb, Vwb pass the virtual neutral point voltage VN.

  In step 109, the time difference between the timer value, which is the position detection interval immediately before 60 degrees obtained in step 108, and the wait time in step 104 is calculated as the determination time.

That is, the position detection determination means 208a calculates the time difference between the position detection interval in the position detection determination means 208a and the wait time in the position detection standby means 208b.

  Next, in step 110, the next commutation time and wait time are set according to the obtained position detection interval.

  As an example, FIG. 2 shows an operation with a conduction angle of 150 degrees and an advance angle of 15 degrees, and the commutation timing is based on 60 degrees obtained at the position detection interval as a reference. , DSy and DSz are set to 0 degrees after position detection, and the OFF timing is set to 30 degrees after position detection. The wait time until the next position detection is started is 45 degrees after the position detection.

  Next, details of the commutation operation will be described with reference to the flowcharts of FIGS. 4 and 5 and the timing waveform of FIG.

  FIG. 4 is a flowchart for the above-described normal control, that is, wide angle control performed at a conduction angle of 150 degrees or less, and FIG. 5 is a flowchart for wide angle control performed at a conduction angle of 150 degrees or more.

  FIG. 6 is a signal waveform diagram above the conduction angle of 150 degrees, and is a timing waveform for the flowchart of FIG. The timing waveform for the flowchart of FIG. 4 is shown in FIG.

  First, the flowchart for the wide angle control performed at a conduction angle of 150 degrees or less in FIG. 4 will be described.

  In step 201, a detection phase in which position detection is performed by the position detection means 208 is determined. If the phase is U, the process proceeds to step 202 and step 203. If the phase is V or W, the process proceeds to step 204.

  Steps 202 and 203 are cases where the detection phase for position detection by the position detection means 208 is the U phase. In step 202, an output signal output from the position detection circuit unit 206 is input to determine the timing of U-phase commutation. In step 203, the U-phase is commutated. This is an operation of receiving the comparator output signal PSu based on the terminal voltage Vu for the operation modes A and D in FIG. 2H and outputting the drive signals DSu and DSx.

  Similarly, the V phase and the W phase will be described.

  In step 204, it is determined whether the detection phase for position detection by the position detection means 208 is V phase or W phase. If it is the V phase, the process proceeds to step 205 and step 206, and if it is the W phase, the process proceeds to step 207 and step 208.

  Step 205 and step 206 are cases where the detection phase for position detection by the position detection means 208 is the V phase. In step 205, the output signal output from the position detection circuit unit 206 is input to determine the U-phase commutation timing, and in step 206, the V-phase is commutated. This is an operation of receiving the comparator output signal PSv based on the terminal voltage Vv with respect to the operation modes C and F of FIG. 2H and outputting it to the drive signals DSv and DSy.

Steps 207 and 208 are cases where the detection phase for position detection by the position detection means 208 is the W phase. In step 207, the output signal output from the position detection circuit unit 206 is input to determine the U-phase commutation timing, and in step 208, the W-phase is commutated. This is an operation of receiving the comparator output signal PSw based on the terminal voltage Vw with respect to the operation modes B and E of FIG. 2H and outputting it to the drive signals DSw and DSz.

  Next, a description will be given of the wide angle control performed above the conduction angle of 150 degrees with reference to FIGS.

  Step 301 determines whether the output signal of the position detection circuit unit 206 is detected by the position detection means 208 at the rising edge or the detection at the falling edge. If it is detected, the process proceeds to step 310.

  The commutation operation in the detection by the falling after Step 302 is the same as Steps 201 to 208 in the flowchart for the wide angle control performed at the conduction angle of 150 degrees or less in FIG.

  In step 302, which corresponds to step 201, the detection phase for position detection by the position detection means 208 is determined. If it is the U phase, the process proceeds to step 303 and step 304, and if it is the V phase or the W phase, the process proceeds to step 305.

  Steps 303 and 304 correspond to steps 202 and 203 when the detection phase for position detection by the position detection unit 208 is the U phase. In step 303, the output signal output from the position detection circuit unit 206 is input to determine the U-phase commutation timing, and in step 204 the U-phase is commutated. This is an operation of receiving the comparator output signal PSu based on the terminal voltage Vu for the operation mode A of FIG. 6H and outputting it to the drive signals DSu and DSx.

  Similarly, the V phase and the W phase will be described.

  Step 305 corresponds to step 204, and determines whether the detection phase for position detection by the position detection means 208 is V phase or W phase. If it is the V phase, the process proceeds to step 306 and step 307, and if it is the W phase, the process proceeds to step 308 and step 309.

  Steps 306 and 307 correspond to steps 205 and 206 when the detection phase for position detection by the position detection means 208 is the V phase. In step 306, the output signal output from the position detection circuit unit 206 is input to determine the timing of commutation of the V phase, and in step 307, the V phase is commutated. This is an operation of receiving the comparator output signal PSv based on the terminal voltage Vv for the operation mode D of FIG. 6H and outputting it to the drive signals DSv and DSy.

  Steps 308 and 309 correspond to steps 207 and 208 when the detection phase for position detection by the position detection unit 208 is the W phase. In step 308, the output signal output from the position detection circuit unit 206 is input to determine the timing of W-phase commutation, and in step 309, the W-phase is commutated. This is an operation of receiving the comparator output signal PSw based on the terminal voltage Vw for the operation mode G in FIG. 6H and outputting it to the drive signals DSw and DSz.

  Next, the case where the output signal of the position detection circuit unit 206 is detected by the rise of the position detection means 208 in step 301 will be described in steps 310 to 314.

  In step 310, the commutation phase in which commutation was performed at the time of detection by falling is determined. If it is the U phase, the process proceeds to step 311, and if it is the V phase or the W phase, the process proceeds to step 312.

  Step 311 is a process performed when the commutation phase that has undergone commutation at the time of detection by the falling edge is the U phase, and commutates the W phase that is a separate phase. This is an operation of receiving the comparator output signal PSu based on the terminal voltage Vu for the operation mode A of FIG. 6H and outputting it to the drive signals DSw and DSz in the operation mode C. When the operation modes A to C of (H) are viewed, it is the rise of the W phase that the position detection means 208 inputs the output signal of the position detection circuit 206 next from the fall of the U phase. The rising edge of the W phase is output based on the falling edge of the U phase.

  That is, in order to widen the energization angle as much as possible, the position detection unit 208 ignores the output signal of the position detection circuit unit 206 with respect to the rise, and energizes the commutation phase from the fall detection position of another phase immediately before the commutation phase. The control is performed by determining the angle, and the energization interval is detected from the time interval of the falling detection of the commutation phase.

  The reference point is set in a separate phase, and the timing of input is set in the target commutation phase, so that the position detection means 208 can output the output signal of the falling position detection circuit 206 from the conduction angle of 150 degrees in general wide angle control. The maximum energization angle is controlled to expand to 165 degrees.

  Hereinafter, the V phase and the W phase when the rising edge is detected will be described in the same manner.

  In step 312, it is determined whether the commutation phase that has undergone commutation at the time of detection by the falling edge is the V phase or the W phase. If it is the V phase, the process proceeds to step 313, and if it is the W phase, the process proceeds to step 314.

  Step 313 is processing performed when the commutation phase that has undergone commutation at the time of detection by falling is the V phase, and commutates the U phase that is a separate phase. This is an operation of receiving the comparator output signal PSv based on the terminal voltage Vv for the operation mode D in FIG. 6H and outputting it to the drive signals DSu and DSx in the operation mode F. When the operation modes D to F of (H) are viewed, it is the rise of the U phase that the position detection means 208 inputs the output signal of the position detection circuit unit 206 next from the fall of the V phase. The rising edge of the U phase is output based on the falling edge of the V phase.

  Step 314 is a process performed when the commutation phase that has undergone commutation at the time of detection by the falling edge is the W phase, and commutates the V phase that is a separate phase. This is an operation of receiving the comparator output signal PSw based on the terminal voltage Vw for the operation mode G of FIG. 6H and outputting the drive signals DSv and DSy in the operation mode I. When the operation modes G to I in (H) are viewed, it is the rise of the V phase that the position detection means 208 inputs the output signal of the position detection circuit 206 next from the fall of the W phase. The rise of the V phase is output based on the fall of the W phase.

  As an example, FIG. 6 shows an operation at an energization angle of 165 degrees, and the falling commutation timing is based on the detection value obtained at the position detection interval as in FIG. The commutation timing is based on the detection of the falling position immediately before each commutation phase, and based on the time obtained at the falling position detection interval of the commutation phase, the drive signals DSu, DSv, DSw, DSx, DSy, Set the DSz ON timing and OFF timing.

  In the present embodiment, the falling commutation timing is maintained at a general wide angle control, and the rising commutation timing is performed based on the detection of the falling position immediately before each commutation phase. However, the same control can be applied to the case where the commutation timing at the rising edge is maintained at the wide angle control and the commutation timing at the falling edge is determined based on the detection of the rising position immediately before each commutation phase. However, the present invention is not limited to this embodiment.

Here, the wide-angle control performed by the microprocessor 207 will be described with reference to FIG.

  FIG. 7 is a flowchart of wide angle control controlled by the microprocessor 207.

  In the wide angle control, it is determined whether to control the energization angle above 150 degrees or below 150 degrees depending on the set values of the duty and the rotational speed.

    In step 401, it is determined whether the duty is greater than or equal to the set value. If the duty is greater than or equal to the set value, the process proceeds to step 402. If the duty is less than the set value, the process proceeds to step 403.

    In step 402, wide angle control is performed in which the duty is equal to or greater than a set value and the energization angle is greater than 150 degrees. The separate phase detection control in the flowchart indicates wide angle control performed above the conduction angle of 150 degrees.

    In step 403, it is determined whether or not the rotational speed is greater than or equal to a set value. If the rotational speed is greater than or equal to the set value, the process proceeds to step 402. If the rotational speed is less than the set value, the process proceeds to step 404.

    In step 404, when both the duty and the rotational speed are less than the set values, normal control, that is, wide angle control with a conduction angle of 150 degrees or less is performed.

  That is, it is determined whether or not the energization angle is higher than 150 degrees depending on the weight of the load. By doing so, it is possible to perform a load operation with finer energization settings.

  As described above, the inverter control device according to the present invention can perform high-efficiency and high-power operation by wide-angle energization control, and can detect the position without losing sight of the rotor magnetic poles with respect to power supply voltage fluctuation. Therefore, reliable and stable operation can be performed, and the present invention can be applied to household electric appliances such as an air conditioner, a refrigerator, and a washing machine, which may be affected by fluctuations in power supply voltage, and electric vehicles. It is also useful in areas where power supply voltage fluctuates frequently.

204 Inverter circuit unit 203 Brushless DC motor 200 Inverter control device 203a Stator 203b Rotor 203α, 203β, 203γ, 203δ, 203ε, 203ζ Permanent magnets 203u, 203v, 203w, stator winding 205 Drive circuit 206 Position detection circuit unit 208 Position detection means 209 Energization angle control means 212 Duty setting means

Claims (7)

An inverter circuit section for driving a brushless DC motor having a permanent magnet provided on the rotor; position detecting means for detecting a relative position of the rotor to the stator based on an induced voltage induced in the stator of the brushless DC motor; An energization angle control means for controlling the energization angle of the inverter circuit unit, and the energization angle control means sets the energization angle in the inverter circuit unit before the zero cross point of the induced voltage based on the detection value of the position detection unit. An inverter control device that performs control of commutation to the inverter circuit and does not use a sensor such as a Hall element in the inverter circuit unit. The output of the conduction angle control means is calculated from the detection value obtained in the past without using the zero cross point of the induced voltage detected by the position detection means at least once during one mechanical angle cycle of the brushless DC motor. The inverter control device according to claim 1, wherein the conduction angle in the inverter circuit unit is commutated before the zero cross point of the induced voltage. Having a duty setting means, and when the energization rate to the brushless DC motor is equal to or greater than a predetermined duty, the energization angle control means determines an energization angle in the inverter circuit unit based on a detection value of the position detection means. The inverter control device according to claim 1 or 2, wherein control for commutation is performed before a zero cross point of the induced voltage. When the rotation speed of the brushless DC motor calculated by the time interval of the zero cross point of the induced voltage detected by the position detection means is equal to or higher than a predetermined rotation speed, the detected value of the position detection means 4. The inverter control device according to claim 1, wherein the control is performed such that the conduction angle in the inverter circuit section is commutated before the zero cross point of the induced voltage. The inverter control device according to any one of claims 1 to 4, wherein a rotor of the brushless DC motor has a configuration in which a permanent magnet is embedded therein and has a saliency. The electric compressor using the inverter control apparatus of any one of Claim 1 to 5. Home electric appliances, such as a refrigerator, using the inverter control device according to any one of claims 1 to 5.