JP4581391B2 - Motor drive device - Google Patents

Description

  The present invention relates to a motor drive device that drives a motor with a sinusoidal alternating current.

  The case where the motor drive device which drives an electric compressor is mounted in a vehicle air conditioner will be described as an example.

  In FIG. 20, reference numeral 101 denotes a blower duct, which sucks air from the air inlet 103 by the action of the indoor blower fan 102 and blows out the air heat-exchanged by the indoor heat exchanger 104 from the air outlet 105 into the vehicle interior.

  The indoor heat exchanger 104 is operated by an electric compressor 106 having a sensorless DC brushless motor as a driving source, a four-way switching valve 107 for switching between a refrigerant flow and selecting cooling or heating, an expansion device 108 and an outdoor fan 109. A refrigeration cycle is configured together with an outdoor heat exchanger 110 that exchanges heat with outside air in the passenger compartment.

  Reference numeral 111 denotes a motor driving device that drives a sensorless DC brushless motor that is a driving source of the electric compressor 106, and its operation is controlled by the air conditioner controller 112 along with the indoor fan 102, the four-way switching valve 107, and the outdoor fan 109. Yes.

  The air conditioner controller 112 includes an indoor blower fan switch 113 for setting automatic / strong / weak / off of indoor ventilation, an air conditioner switch 114 for selecting cooling / heating / operation OFF, a temperature control switch 115, an air conditioning temperature sensor 117, and a vehicle. A communication device 116 for communicating with a controller (not shown) is connected.

  FIG. 20 shows the arrangement of the air conditioner on a vehicle.

  In the figure, an outdoor heat exchanger 110, an outdoor fan 109, an electric compressor 106, a motor driving device 111, and the like are arranged and fixed on an outdoor vehicle body in front of the vehicle, and an indoor fan 102, an indoor heat exchanger 104, and an air conditioner controller 112. Etc. are arranged indoors. In these arrangements on the vehicle, since the vehicle running device is given priority, it is desired to be small and light.

  On the other hand, noise vibration of the electric compressor 106 fixed to the vehicle body is transmitted through the vehicle body to the vehicle interior. In addition, noise is spread around the vehicle. Therefore, the operation of the electric compressor 106 is required to have low noise and low vibration. Since the vehicle is parked outdoors and the interior of the vehicle is hot in summer and cold in winter, a large air conditioning capacity is required at the start of air conditioning.

  Conventionally, a 120-degree energization method is used for DC-AC conversion of a motor drive device (see, for example, Patent Document 1).

  This 120-degree energization method is disadvantageous in terms of noise and vibration because commutation is performed every 60 degrees. Therefore, recently, a sine wave driving method for outputting a sine wave AC current has begun to be used (see, for example, Patent Document 2).

  In this sine wave drive system, a concentrated winding motor can be used as the motor of the electric compressor, and the electric compressor can be miniaturized. Moreover, since there is no commutation and the output is a sinusoidal alternating current, the electric compressor can be driven with low noise and low vibration.

  22 to 27 show the waveforms of the three-phase modulation and the two-phase modulation in the sine wave driving method.

  In the figure, 41 represents a U-phase terminal voltage, 42 represents a V-phase terminal voltage, 43 represents a W-phase terminal voltage, and 29 represents a neutral point voltage. Since the output of the motor driving device is connected to a terminal of the motor, the terminal voltage may be read as the output voltage of the motor driving device or the input voltage of the motor. The neutral point voltage is a value obtained by calculating the sum of the terminal voltages of the respective phases and dividing by 3, and the phase voltage is a value obtained by subtracting the neutral point voltage from the terminal voltage.

FIG. 22 shows three-phase modulation with 50% modulation, and FIG. 23 shows three-phase modulation with 100% modulation.
It has been experimentally confirmed that the three-phase modulation has lower noise and vibration than the two-phase modulation.

  FIG. 24 shows two-phase modulation with 50% modulation, and FIG. 25 shows two-phase modulation with 100% modulation. In the two-phase modulation, the non-modulation phase (for example, the W phase from 90 degrees to 210 degrees) is 0% duty (duty), and the U phase and V phase indicate the difference.

  Here, the phase voltage of the V phase is represented by Sin θ, and the phase voltage of the W phase is represented by sin (θ−120). θ indicates the phase. In the case of three-phase modulation, since the terminal voltage has the same waveform and amplitude, 100% modulation requires a DC voltage of 2 on the plus and minus sides.

  On the other hand, in the case of two-phase modulation, the terminal voltage is represented by sin θ−sin (θ−120) and becomes √3 · sin (θ + 30). Since it is only on the positive side, a DC voltage of √3 is required for 100% modulation. Therefore, at the same DC voltage, the maximum phase voltage is 1.15 times (2 / √3≈15% larger) in the two-phase modulation than in the three-phase modulation.

    FIG. 26 shows two-phase modulation in which the non-modulation phase (for example, the U phase from 30 degrees to 150 degrees) is Duty 100%. Further, in FIG. 27, the non-modulation phase is alternately changed to Duty 0% and Duty 100% (for example, the U phase is Duty 100% at a phase of 60 degrees to 120 degrees, and the W phase is Duty 0% at a phase of 120 degrees to 180 degrees). Indicates phase modulation.

The two-phase modulation in both FIG. 26 and FIG. 27 has the same relationship with the three-phase modulation.
JP-A-8-163891 JP 2000-217384 A

  However, in the conventional configuration, the motor can be reduced in size and reduced in noise and vibration by the sine wave drive method, but the maximum output is larger in the two-phase modulation, but the noise vibration is larger than the three-phase modulation. Although the noise and vibration are lower than the modulation, the maximum output is smaller than the two-phase modulation, and it is difficult to obtain a large air conditioning capacity at the start of air conditioning. Further, when the power supply voltage is boosted and the maximum output is increased in the three-phase modulation, the booster increases the size and weight.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide a motor drive device that is low noise, low vibration, large maximum output, small and light.

In order to solve the above-described conventional problems, the motor driving device of the present invention has the same modulation period for all phases including a non-modulated phase in a carrier cycle for switching of two-phase modulation that outputs a sinusoidal alternating current. In addition, three-phase modulation is performed , and the modulation period to be added is half of the non-energization period in the carrier period before the addition .

  As a result, while the phase voltage due to the two-phase modulation is maintained, there are a plurality of energization periods within the carrier cycle, the sinusoidal alternating current becomes smooth, and the carrier noise can be reduced by the same action as increasing the carrier frequency. .

  The motor drive device of the present invention can achieve both of two-phase modulation large output and three-phase modulation low noise and low vibration. Accordingly, a small and light motor driving device having low noise, low vibration and a large maximum output can be obtained.

1st invention adds the same modulation period to all phases including a non-modulation phase in a carrier cycle to switching of 2-phase modulation which outputs a sine wave-like alternating current, and makes it 3 phase modulation, and adds modulation By setting the period to half of the non-energization period in the carrier cycle before the addition, the phase voltage by the two-phase modulation is maintained and there are a plurality of energization periods in the carrier period, and the sinusoidal alternating current becomes smooth. The operation is equivalent to increasing the carrier frequency, and at the same time, the intervals of the energization periods are always equal.

As a result, it is possible to achieve both high output of two-phase modulation, low noise and low vibration of three-phase modulation, and to smoothly continue the connection in the same manner from the low modulation region to the high modulation region. Moreover, it can be realized simply by adding software such as a microcomputer.

In particular, in the motor drive device of the first invention , the second invention adds a modulation period only at a highly effective phase by adding a modulation period at a specific phase, and a switching loss due to the addition of the modulation period. Can be reduced.

In particular, in the motor drive device according to the first aspect of the present invention , by adding a modulation period at a specific rotation speed, a modulation period is added only at a highly effective rotation speed. Switching loss can be reduced.

In the fourth aspect of the invention , in particular, by driving the motor of the air conditioning compressor in the motor driving device of the first to third aspects of the invention, a comfortable air conditioning can be obtained that is quick in start-up and low in noise and vibration.

The fifth aspect of the invention is particularly applicable to a vehicle in which a motor of an air conditioning compressor mounted on a vehicle is driven by the motor driving device of the fourth aspect of the invention so that the heat load is large and noise vibration is easily transmitted. Comfortable air-conditioning can be obtained by quick start-up, low noise and low vibration.

  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 waveform diagram showing an example of an output voltage of the motor drive device according to the first embodiment of the present invention.

  FIG. 1 is obtained by adding a duty of 25% to the output voltage (motor terminal voltage) of all three phases of the motor drive device by the two-phase modulation of FIG. Since the neutral point voltage is a value obtained by calculating the sum of the terminal voltages of the respective phases and dividing by 3, the neutral point voltage also has a large 25% duty. Since the phase voltage is a value obtained by subtracting the neutral point voltage from the terminal voltage, the duty of 25% is canceled and the value of the phase voltage does not change. Since all three phases are modulated, this is one type of three-phase modulation. This is defined as three-phase modulation A with respect to the conventional three-phase modulation (FIGS. 22 and 23).

  The operation and action of the above will be described below.

  First, the electric circuit according to the first embodiment will be described with reference to FIGS.

  In FIG. 2, reference numeral 1 denotes a battery, and reference numeral 10 denotes an inverter circuit, which includes a plurality of inverter operation switching elements 2 connected to the battery 1 and an inverter operation diode 3.

Here, for the switching element 2, the upper arm switching element is defined as U, V, W, and the lower arm switching element is defined as X, Y, Z, and each switching element U, V, W, X, Y, Z is defined as Corresponding diodes are defined as 3U, 3V, 3W, 3X, 3Y, 3Z.

  Reference numeral 11 denotes a sensorless DC brushless motor (hereinafter referred to as a motor), which includes a stator winding 4 of the motor and a magnet rotor 5 of the motor. 6 is a current sensor for detecting a power supply current, 8 is a current sensor for detecting a U-phase current, and 9 is a current sensor for detecting a W-phase current. Reference numeral 7 denotes a control circuit that controls the switching element 2 based on a rotation speed instruction value (not shown) from the air conditioner controller and signals from the current sensors 6, 8, 9 and the like. Reference numeral 20 denotes a motor drive device as a rotation speed control means.

  The detected current value of the current sensor 6 is sent to the control circuit 7 and used for power consumption calculation and determination for protecting the switching element 2 and the like. The current sensor 6 may be any sensor that can detect the peak of the switching current by the switching element 2, such as a sensor using a Hall element, a shunt resistor, or the like as is well known. In FIG. 2, the current sensor 6 is provided on the minus side of the power supply line. However, since the current is the same, it may be provided on the plus side.

  In FIG. 3, the current sensor 8 for detecting the U-phase current and the current sensor 9 for detecting the W-phase current are not provided, and the detected current value of the current sensor 6 is also used for calculating the induced voltage. When one of the upper arm switching elements U, V, and W is ON, a current of that phase flows through the current sensor 6. When the two are ON, the current sensor 6 passes through the current of the remaining phase. Since the control circuit 7 controls the switching element 2, it can determine which element is ON. Therefore, the phase current can be detected. Therefore, the current sensor can be reduced and the size and weight can be reduced.

  Next, switching within one carrier (carrier cycle) will be described.

FIG. 4 shows an example of switching of the upper arm switching elements U, V, W and the lower arm switching elements X, Y, Z in the carrier period in FIG. This is a case where the phase is approximately 120 degrees. The ON period of the W phase corresponds to the added 25%.
There are four patterns (a), (b), (c), and (d) as timing.

  At timing (a), all the upper arm switching elements U, V, W are OFF, and all the lower arm switching elements X, Y, Z are ON. FIG. 5 shows an example of the current flow at this time. U-phase current and V-phase current flow from the diodes in parallel with the lower arm switching elements X and Y to the stator winding 4, respectively, and W-phase current flows from the stator winding 4 to the lower arm switching element Z. Therefore, no current flows through the power supply line, no power is supplied from the battery 1 to the stator winding 4, and no power is supplied.

  At timing (b), the upper arm switching element U is ON, and the lower arm switching elements Y and Z are ON. FIG. 6 shows the current flow at this time. The U-phase current flows from the upper arm switching element U to the stator winding 4, the V-phase current flows from the diode parallel to the lower arm switching element Y to the stator winding 4, and the W-phase current flows to the stator winding 4. To the lower arm switching element Z. Therefore, a current flows through the power supply line, electric power is supplied from the battery 1 to the stator winding 4, and the power supply line is energized.

  At timing (c), the upper arm switching elements U and V are ON, and the lower arm switching element Z is ON. FIG. 7 shows the current flow at this time. The U-phase current and the V-phase current flow from the upper arm switching elements U and V to the stator winding 4, respectively, and the W-phase current flows from the stator winding 4 to the lower arm switching element Z. Therefore, a current flows through the power supply line, electric power is supplied from the battery 1 to the stator winding 4, and the power supply line is energized.

  At timing (d), all the upper arm switching elements U, V, W are ON, and all the lower arm switching elements X, Y, Z are OFF. FIG. 8 shows the current flow at this time. The U-phase current and the V-phase current flow from the upper arm switching elements U and V to the stator winding 4 respectively, and the W-phase current flows from the stator winding 4 to the diode in parallel with the upper arm switching element W. . Therefore, no current flows through the power supply line, no power is supplied from the battery 1 to the stator winding 4, and no power is supplied.

  As described above, the power supply current does not flow during the timing (a) and timing (d) within the carrier cycle (no energization). For this reason, the energization is divided into the first half and the second half within the carrier cycle. This has the same effect as doubling the carrier frequency (halving the carrier period), and carrier noise is reduced. Also, the sine wave current becomes smooth. On the other hand, as described above, the phase voltage of the two-phase modulation does not change.

  This is illustrated in FIG. FIG. 9 is the same as FIG. 1 except that the ON state of the upper arm switching elements U, V, and W within one carrier (carrier cycle) at the phases of 90 degrees, 105 degrees, 120 degrees, 135 degrees, and 150 degrees is equally distributed from the center. This is a sort display. The ON phase of the U phase is represented by a thin solid line, the ON period of the V phase is represented by a solid solid line, and the ON period of the W phase is represented by a thick solid line. Under the ON period, an energization period in which power is supplied from the battery 1 to the stator winding 4 is indicated by a solid line arrow, and a non-energization period is indicated by a broken line arrow.

  At 90 degrees in phase, as shown in FIG. 1, U phase modulation is 68%, V phase modulation is 25%, and W phase modulation is 25%. Therefore, assuming 1 carrier (carrier cycle) as 100%, U phase is 68%, V-phase 25% and W-phase 25% are equally distributed from the center. The same applies to the other phases.

  The reason why the phase is set to 90 degrees to 150 degrees is because this pattern is repeated although the phases are different.

  As is clear from FIG. 9, the energization is performed in two parts, the first half and the second half, within the carrier period. In addition, 25% modulation is added to each of the three phases, but since this period is a (non-carrier period center) non-energization period, during the energization period when power is supplied from the battery 1 to the stator winding 4 There is no change. Therefore, the operation of the two-phase modulation according to FIG. 24 remains unchanged.

  As is clear from the above, the modulation to be added is not limited to 25%, and it is sufficient that all three phases have the same value.

  FIG. 10 shows an upper arm timing diagram of the conventional three-phase modulation shown in FIG. As in FIG. 9, the energization is divided into the first half and the second half within the carrier period. Therefore, low noise and low vibration are obtained by the same action.

On the other hand, the upper and lower arm timing chart of the two-phase modulation is shown in FIG. Compared to FIG. 4, the W phase is unmodulated (OFF), so there is no period of timing (d). FIG. 12 shows an upper arm timing chart of the two-phase modulation based on FIG. FIG. 13 shows an upper arm timing diagram of the two-phase modulation based on FIG. In both FIG. 12 and FIG. 13, energization is performed only once within the carrier period. Therefore, the three-phase modulation and the three-phase modulation A can reduce noise and vibration compared to the two-phase modulation.

  FIG. 9 is obtained by adding 25% modulation (ON period) to the three phases in FIG.

When modulation is added to FIG. 13, since the non-energization period is short and less effective, the switching loss may be reduced by limiting to a specific phase (switching increases and loss increases when modulation is added).

FIG. 14 shows a timing diagram of the upper and lower arms of the two-phase modulation based on FIG. When modulation is added to this, an OFF period may be added. Similarly, when adding to the two-phase modulation of FIG. 27, an ON period and an OFF period may be selected and added depending on the phase.
As described above, in the present embodiment, the switching of the inverter circuit that outputs a sinusoidal alternating current is set to two-phase modulation, and the same modulation period is added to all phases including the non-modulation phase within the carrier cycle. Thus, since the energization period in the carrier cycle is divided into two while maintaining the phase voltage by the two-phase modulation, the sinusoidal alternating current becomes smooth, and the same effect as that obtained by increasing the carrier frequency can be obtained.

  Therefore, it is possible to achieve both high output of two-phase modulation and low noise and vibration of three-phase modulation. Further, since only the same modulation period is added, it can be easily realized only by adding software such as a microcomputer.

  FIG. 15 is a waveform diagram showing an example of the output voltage of the motor drive device according to the second embodiment of the present invention. The output voltages (motor terminal voltages) of all three phases of the motor drive device based on the two-phase modulation shown in FIG. Further, a modulation period equal to half of the non-energization period in the carrier period before the addition is added.

  Since the neutral point voltage is a value obtained by calculating the sum of the terminal voltages of each phase and dividing by 3, the neutral point voltage is also increased by the additional modulation period. Since the phase voltage is a value obtained by subtracting the neutral point voltage from the terminal voltage, the additional modulation period is canceled and the value of the phase voltage does not change. Since all three phases are modulated, this is one type of three-phase modulation. This is defined as three-phase modulation B with respect to the conventional three-phase modulation (FIGS. 22 and 23).

  FIG. 16 shows the ON state of the upper arm switching elements U, V, and W within one carrier (carrier cycle) at 90 degrees, 105 degrees, 120 degrees, 135 degrees, and 150 degrees in FIG. This is a sort display.

  In FIG. 12, the modulation period equal to half of the total of the first half and the latter half of the non-energization period (first half or the latter half of the non-energization period) in the carrier cycle is the same.

  As in the case of the three-phase modulation A, the energization is performed in the first half and the second half in the carrier period. Further, the same modulation (for the additional modulation period) is added to each of the three phases, but since this period is a non-energization period (center in the carrier cycle), power is supplied from the battery 1 to the stator winding 4. There is no change in the energization period. Therefore, the operation of the two-phase modulation according to FIG. 24 remains unchanged. In addition, since the intervals of the energization periods including the front and rear carrier periods are equal, the sine wave current becomes smoother than in the conventional three-phase modulation or three-phase modulation A. Thus, further low noise and low vibration can be achieved.

  17 is an output voltage of three-phase modulation B based on the two-phase modulation of FIG. 25, and FIG. 18 is an upper arm timing diagram based on FIG. Therefore, since the same calculation method (software) can be applied uniformly from low modulation to 100% modulation (two-phase modulation in FIG. 25), it is possible to smoothly connect modulation from the low modulation region to the high modulation region.

  As described above, in the present embodiment, in the first embodiment, by adding the modulation period to be added to half of the non-energization period in the carrier cycle before the addition, the intervals of the energization periods are always equal. Furthermore, low noise and vibration are obtained. Connections can be made smoothly and smoothly in the same manner from the low modulation region to the high modulation region.

(Embodiment 2 )
FIG. 19 shows only a specific phase (90 degrees, 150 degrees) without modulation addition in the phase where the non-energization period is short and the effect is small in FIG. It can also be applied to three-phase modulation A.

  In the present embodiment, it is possible to reduce the switching loss (addition of modulation increases the switching loss) while taking advantage of the operations and effects of the first embodiment and the second embodiment.

  In each of the above embodiments, the modulation to be added may be divided into two or more times, and the energization period may be plural. Further, modulation may be added only to a low rotational speed region where low noise and low vibration are required, mechanical noise is low and carrier noise is conspicuous, and high rotational speed region where both mechanical noise and carrier noise are desired to be reduced.

  As described above, since the motor drive device according to the present invention has both high output of two-phase modulation and quietness of three-phase modulation in sinusoidal drive, the motor drive device for home appliances and for running an electric vehicle The present invention can also be applied to uses such as motor drive devices, industrial motor drive devices, and motor drive devices using induction motors.

The wave form diagram which shows the output voltage example of the motor drive device in Embodiment 1 of this invention. Electrical circuit diagram of the first embodiment Electric circuit diagram of a different example in the first embodiment Upper and lower arm timing diagram showing switching within the same carrier period Electrical circuit diagram showing current path at the same timing (a) Electrical circuit diagram showing current path at the same timing (b) Electrical circuit diagram showing current path at the same timing (c) Electrical circuit diagram showing current path at the same timing (d) Upper arm timing diagram showing examples of upper arm ON period, energization period, and non-energization period within the same carrier cycle Upper arm timing diagram showing an example of the upper arm ON period, energization period, and non-energization period within the carrier period in three-phase modulation Upper and lower arm timing diagrams showing switching within the carrier period in two-phase modulation Upper arm timing diagram showing examples of upper arm ON period, energization period, and non-energization period within the carrier period in two-phase modulation Upper arm timing diagram showing examples of other upper arm ON period, energization period, and non-energization period within the carrier period in two-phase modulation Upper and lower arm timing diagrams showing other switching within the carrier period in two-phase modulation The wave form diagram which shows the example of the output voltage of the motor drive unit in Embodiment 2 of this invention Upper arm timing diagram showing examples of upper arm ON period, energization period, and non-energization period within the same carrier cycle Waveform diagram showing another output voltage example of the motor drive device Upper arm timing diagram showing examples of other upper arm ON periods, energization periods, and non-energization periods within the same carrier cycle Upper arm timing chart showing examples of upper arm ON period, energization period, and non-energization period in Embodiment 3 of the present invention Configuration diagram of a vehicle air conditioner equipped with a conventional electric compressor Layout showing the arrangement of the vehicle air conditioner in the vehicle Waveform diagram showing an example of output voltage by three-phase modulation of a conventional motor drive device Waveform diagram showing another example of output voltage by three-phase modulation of a conventional motor drive device Waveform diagram showing an example of output voltage by two-phase modulation of a conventional motor drive device Waveform diagram showing another example of output voltage by two-phase modulation of a conventional motor drive device Waveform diagram showing two-phase modulation with the non-modulated phase as 100% modulation Waveform diagram showing two-phase modulation where the non-modulated phase is switched alternately between 100% and 0% modulation

DESCRIPTION OF SYMBOLS 1 Battery 2 Switching element 10 Inverter circuit 11 Motor 20 Motor drive device 1
21 Motor drive device 2

Claims (5)

An inverter circuit that outputs a sinusoidal alternating current by switching a direct current voltage by three-phase modulation is provided, and the three-phase modulation is used for switching two-phase modulation that outputs a sinusoidal alternating current within a carrier cycle. A motor driving device characterized by three-phase modulation obtained by adding a modulation period that is the same for all phases including a non-modulation phase and is half of the non-energization period in the carrier cycle. The motor driving device according to claim 1, wherein a modulation period is added in a specific phase. The motor driving device according to claim 1, wherein a modulation period is added at a specific rotation speed. The motor drive device according to claim 1 , wherein the motor of an air conditioning compressor is driven. The motor drive device of Claim 4 which drives the motor of the compressor for an air conditioning mounted in a vehicle.

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