JP2004282884A - Motor drive unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor drive unit which has a low noise and a low vibration and which has a small size and a light weight. <P>SOLUTION: This motor drive unit uses a current sensor 6 for detecting power supply current also as the current detection of a stator winding 4, and adds or subtracts the same energization time during the energization period within a carrier period of each phase to detect the position of the magnet rotor 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a motor driving device provided with an inverter circuit for driving a sensorless DC brushless motor.
[0002]
[Prior art]
A vehicle air conditioner equipped with a conventional electric compressor using a sensorless DC brushless motor as a drive source will be described.
[0003]
In FIG. 24, reference numeral 101 denotes a blower duct, which sucks air from an air inlet 103 by the action of an indoor blower fan 102 and blows out the air exchanged by the indoor heat exchanger 104 from an air outlet 105 into a vehicle cabin.
[0004]
The indoor heat exchanger 104 is operated by an electric compressor 106 driven by a sensorless DC brushless motor, a four-way switching valve 107 for switching the flow of refrigerant to select cooling and heating, a throttle device 108, and an outdoor fan 109. The refrigeration cycle is configured together with the outdoor heat exchanger 110 that exchanges heat with the vehicle outdoor air.
[0005]
A motor driving device 111 drives a sensorless DC brushless motor that is a driving source of the electric compressor 106. The operation of the motor driving device 111 is controlled by the air conditioner controller 112 together with the indoor blower fan 102, the four-way switching valve 107, and the outdoor blower fan 109. I have.
[0006]
The air conditioner controller 112 includes an indoor air blower fan switch 113 for setting ON / OFF and strength of indoor air blow, an air conditioner switch 114 for selecting cooling / heating / OFF, a temperature adjustment switch 115, and a communication device for communicating with the vehicle controller. 116.
[0007]
For example, when the air is turned ON / low by the indoor fan switch 113 and cooling is instructed by the air conditioner switch 114, the air conditioner controller 112 sets the four-way switching valve 107 to the solid line in the figure and evaporates the indoor heat exchanger 104. The outdoor heat exchanger 110 is operated as a condenser, the outdoor blower fan 109 is turned on, and the indoor blower fan 102 is set to weak.
[0008]
Further, the temperature of the indoor heat exchanger 104 is adjusted by changing the rotation speed of the electric compressor 106 using the motor driving device 111 according to the temperature adjustment switch 115. When the air conditioner switch 114 turns off the cooling and heating, the electric compressor 106 and the outdoor blower fan 109 are turned off.
[0009]
When the indoor blower fan switch 113 is turned off, the indoor blower fan 102 is turned off, and the electric compressor 106 and the outdoor blower fan 109 are also turned off for refrigeration cycle protection.
[0010]
On the other hand, when a cooling / heating OFF command is received from the vehicle controller (not shown) via the communication device 116 for reasons such as power saving and battery protection, the air conditioner controller 112 performs the same processing as the cooling / heating OFF by the air conditioner switch 113. do.
[0011]
In a vehicle air conditioner equipped with such an electric compressor, low noise and low vibration are important. In particular, since electric vehicles have no engine, they have high quietness (in hybrid electric vehicles, they run on a motor without starting the engine). Furthermore, when the vehicle is stopped, the electric compressor is driven by the battery power supply. In this case, there is no noise and vibration due to running, so that the noise and vibration of the electric compressor become conspicuous.
[0012]
When the motor driving device 111 is a conventional 120-degree energizing method, the magnetic field change is at 60-degree intervals (energization is at 60-degree intervals), so the sensorless DC brushless motor, which is the drive source of the electric compressor 106, has torque fluctuations. This causes noise and vibration. (For example, see Patent Document 1)
FIG. 25 shows a circuit example. In the figure, reference numeral 121 denotes a battery, 122 denotes an inverter operation switching element connected to the battery 121, and 123 denotes an inverter operation diode. Reference numeral 124 denotes a stator winding of the motor, and reference numeral 125 denotes a magnet rotor of the motor.
[0013]
Reference numeral 126 denotes a current sensor for detecting a power supply current to calculate power consumption and protect switching elements, and 127 denotes a phase shift circuit for detecting the position of the magnet rotor 5 from the voltage of the stator winding. And 128 is a comparison circuit.
[0014]
Reference numeral 129 denotes a control circuit that controls the switching element based on signals from the current sensor 126, the comparison circuit 128, and the like.
[0015]
On the other hand, in the case of the sine wave drive, since the permanent magnet rotor is driven by a continuous rotating magnetic field, torque fluctuation is reduced. Therefore, it is desirable to use a sine wave drive motor drive device that outputs a sine wave current. However, for detecting the position of the permanent magnet rotor, two current sensors are used to detect the current of the stator winding (for example, see Patent Document 2).
[0016]
FIG. 26 shows a circuit example. Compared with FIG. 25, there is no comparison circuit 128 / phase shift circuit 127, and a U-phase current detection current sensor 130 and a W-phase current detection current sensor for detecting the position of the magnet rotor 125 from the stator winding current. 131. The control circuit 129 calculates another one-phase current based on the current values for the two phases from the two current sensors (two current sensors are required, but among the U-phase, V-phase, and W-phase). The position of the magnet rotor 125 is detected, and the switching element is controlled based on a signal from the current sensor 126 or the like. Reference numeral 117 denotes a sine-wave drive motor drive device that replaces the 120-degree current drive motor drive device 111.
[0017]
In addition to the low noise and low vibration described above, the motor drive device is required to be small and light in terms of securing mountability and running performance.
[0018]
[Patent Document 1]
JP-A-8-163891 (page 8, FIG. 4)
[Patent Document 2]
JP-A-2000-333465 (page 9, FIG. 2)
[0019]
[Problems to be solved by the invention]
As described above, the use of the sine-wave drive motor driving device that outputs a sine-wave current has an advantage that torque fluctuation is reduced. However, in the conventional configuration shown in FIG. 26, the position of the magnet rotor is detected. For this reason, two current sensors are required, and this has a problem that it becomes a hindrance factor in advancing miniaturization and weight reduction as a motor drive device.
[0020]
An object of the present invention is to solve such a conventional problem, and an object of the present invention is to provide a small and lightweight motor drive device which has low noise and low vibration.
[0021]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention is to detect the position of a magnet rotor by using a current sensor for detecting a power supply current also for detecting a current of a stator winding. In this current detection, the same energization time is added or subtracted during the energization period in the carrier cycle of each phase, and the addition or subtraction is performed by dividing the first half or the second half or the first half and the second half of the carrier cycle by each phase. Is selected.
[0022]
With the above configuration, sine-wave driving becomes possible without adding two current sensors for phase current detection, and a conventional phase shift circuit and comparison circuit for 120-degree conduction is unnecessary, and the number of components is reduced. A small, lightweight, and highly reliable motor drive device with low noise and low vibration can be obtained.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0024]
(Embodiment 1)
FIG. 1 shows an electric circuit diagram of the present embodiment. In the figure, 1 is a battery, 2 is an inverter operation switching element connected to the battery 1, and 3 is an inverter operation diode. Reference numeral 4 denotes a stator winding of the motor, and reference numeral 5 denotes a magnet rotor of the motor.
[0025]
Further, a control circuit 7 controls the switching element based on a signal from the current sensor 6. Reference numeral 20 denotes a motor driving device of the present invention which replaces the conventional motor driving device 111.
[0026]
Comparing the electric circuit diagram of FIG. 1 with the electric circuit diagram for 120-degree conduction driving of FIG. 25, the comparison circuit 128 and the phase shift circuit 127 are omitted.
[0027]
Also, comparing the electric circuit diagram of FIG. 1 with the electric circuit diagram for driving a sine wave provided with the current sensor for detecting phase current in FIG. 26, the current sensor 130 for detecting U-phase current and the current sensor 131 for detecting W-phase current are shown. Has been removed.
[0028]
The detected current value of the current sensor 6 is sent to the control circuit 7 and is used for power consumption calculation, determination for protection of the switching element 2 and the like, and further used for position detection of the magnet rotor 5.
[0029]
Therefore, the control circuit 7 can reduce the number of signal input circuits (hardware) for the comparison circuit 128 in FIG. 25, the U-phase current detection current sensor 130 and the W-phase current detection current sensor 131 in FIG. Should be done.
[0030]
Then, the switching element 2 is controlled based on a rotation speed command signal (not shown) and the like. The current sensor 6 may be a sensor using a Hall element, a shunt resistor, or the like, as long as it can detect the peak of the switching current by the switching element 2.
[0031]
Conventionally, the current sensor 6 can detect the peak of the switching current in order to protect the switching element 2 and the like, and thus can be used as it is.
[0032]
In FIG. 1, the current sensor 6 is inserted on the negative side of the power supply line, but may be on the positive side because the current is the same. By adopting such a configuration, the number of components is reduced as compared with the related art, so that the size can be reduced and the reliability such as vibration resistance can be improved (the current sensor and the like are mounted on a printed circuit board). This is a concern for anti-vibration).
[0033]
Next, a method for detecting the position of the magnet rotor 5 will be described with reference to FIG.
[0034]
In the figure, the relationship between the phase current and the induced voltage in the U phase is shown. Since the induced voltage is a voltage induced in the stator winding 4 by the rotation of the magnet rotor 5 shown in FIG. 1, it can be used for detecting the position of the magnet rotor 5.
[0035]
In the stator winding 4 shown in FIG. The sum of the induced voltage, the voltage of the inductance L, and the voltage of the resistor R is equal to the voltage applied from the motor drive device 20. Assuming that the induced voltage is EU, the phase current is iU, and the applied voltage is VU, VU = EU + R.iU + Ld.iU / dt (FIG. 3 shows an example of one phase of the voltage and current of the sensorless DC brushless motor). , The induced voltage EU is represented by EU = VU-RＲiU-Ld ・ iU / dt.
[0036]
Since the control circuit 7 in FIG. 1 controls the switching element 2, the applied voltage VU is known. Therefore, if the values of the inductance L and the resistance R are input to the program software of the control circuit 7, the induced voltage EU can be calculated by detecting the phase current iU.
[0037]
Next, a method for detecting the position of the magnet rotor 5 with the current sensor 6 will be described.
[0038]
First, a waveform of three-phase modulation will be described. 4 shows three-phase modulation with a maximum modulation of 100%, FIG. 5 shows three-phase modulation with a maximum modulation of 50%, and FIG. 6 shows three-phase modulation with a maximum modulation of 10%.
[0039]
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. The three-phase modulation extends in both directions of 0% and 100% around 50% as the degree of modulation increases.
[0040]
Next, an example will be described with reference to the drawings. FIG. 7 shows an example of energization of the upper arm switching elements U, V, W and the lower arm switching elements X, Y, Z within one carrier (carrier cycle). In this case, in the three-phase modulation with the maximum modulation of 50% in FIG. 5, the current is supplied at a phase of approximately 130 degrees. There are four energization patterns: (a), (b), (c), and (d).
[0041]
In the energization pattern (a), all of the upper arm switching elements U, V, and W are OFF, and all of the lower arm switching elements X, Y, and Z are ON. FIG. 8 shows the current flow at this time.
[0042]
The U-phase current and the V-phase current respectively flow from the diodes in parallel with the lower arm switching elements X and Y to the stator winding 4, and the W-phase current flows from the stator winding 4 to the lower arm switching element Z. Therefore, no current flows through the current sensor 6 and is not detected.
[0043]
In the energization pattern (b), the upper arm switching element U is ON, and the lower arm switching elements Y and Z are ON. FIG. 9 shows the current flow at this time.
[0044]
The U-phase current flows from the upper arm switching element U to the stator winding 4, the V-phase current flows from a diode in parallel with the lower arm switching element Y to the stator winding 4, and the W-phase current Out of the lower arm switching element Z. Therefore, the U-phase current flows through the current sensor 6 and is detected.
[0045]
In the energization pattern (c), the upper arm switching elements U and V are ON, and the lower arm switching element Z is ON. FIG. 10 shows the current flow at this time.
[0046]
The U-phase current and the V-phase current respectively flow from the upper arm switching elements U and V to the stator winding 4, and the W-phase current flows from the stator winding 4 to the lower arm switching element Z. Therefore, the W-phase current flows through the current sensor 6 and is detected.
[0047]
In the energization pattern (d), all of the upper arm switching elements U, V, and W are ON, and all of the lower arm switching elements X, Y, and Z are OFF. FIG. 11 shows the current flow at this time.
[0048]
The U-phase current and the V-phase current respectively flow from the upper arm switching elements U and V to the stator winding 4, and the W-phase current flows from the stator winding 4 from the upper arm switching element W. Therefore, no current flows through the current sensor 6 and is not detected.
[0049]
As described above, since the U-phase current and the W-phase current are detected, the remaining V-phase current is obtained at the neutral point of the stator winding 4 by applying Kirchhoff's current law.
[0050]
In this case, the U-phase current is a current flowing into the neutral point of the stator winding 4, and the W-phase current is a current flowing from the neutral point of the stator winding 4, so that the V-phase current is the U-phase current and the W-phase current. It can be obtained by taking the difference between the currents.
[0051]
In the three-phase modulation, as described above, the power supply current does not flow (the current does not flow to the current sensor 6) during the period of the conduction pattern (d) in the carrier cycle. For this reason, the power is supplied to the first half and the second half in the carrier cycle. This means that the carrier frequency is the same as twice (the carrier cycle is half), and the carrier noise is reduced. Accordingly, low noise and low vibration can be achieved.
[0052]
Since the above current detection can be performed for each carrier, the position can be detected for each carrier, and the output to the stator winding 4 can be adjusted. Therefore, the torque fluctuation is small compared to the 120-degree conduction, and low noise and low vibration can be realized. In addition, startability is improved.
[0053]
It can be seen that the phase current that can be detected by the current sensor 6 is determined in the ON and OFF states of the upper arm switching elements U, V, W. When only one phase is ON, the current of that phase can be detected when the two phases are ON, and cannot be detected when the three phases are ON and there is no ON phase. Therefore, the detectable phase current can be known by confirming that the upper arm switching elements U, V, W in one carrier are ON. In FIG. 7, the ON state of each phase of the upper arm may be confirmed.
[0054]
In FIG. 12, a current that can be detected using this fact can be examined. Turning on the upper arm switching elements U, V, and W within one carrier (carrier cycle) at the phases of 30 degrees, 45 degrees, 60 degrees, 75 degrees, and 90 degrees in the three-phase modulation of 100% maximum modulation in FIG. The energized state is evenly distributed and displayed from the center.
[0055]
The energization period of the U phase is represented by a thin solid line, the energization period of the W phase is represented by a thick solid line, and the energization period of the V phase is represented by a solid line. Further, U and V indicated by arrows below each energization period indicate a U-phase current detectable period and a V-phase current detectable period, respectively.
[0056]
At 30 degrees, as shown in FIG. 4, the U-phase modulation is 75% and the W-phase modulation is 75%, so that one carrier (carrier cycle) is set to 100%, and the U-phase (fine line) modulation (energization time), W Both the phase (thick line) modulation (energization time) and 75% are uniformly displayed from the center. The same applies to other phases.
[0057]
The reason for setting the angle to 30 degrees to 90 degrees is that the energization time pattern is repeated, although the energized phases are different.
[0058]
Similarly, FIG. 13 shows the case of 50% maximum modulation, FIG. 14 shows the case of 10% maximum modulation, and FIG. 14 shows the case of 5% maximum modulation.
[0059]
Here, at the phases of 30 degrees and 90 degrees in FIGS. 12, 13, and 14, the energization times of the two phases match, so that the detection time by the current sensor 6 cannot be secured and the current of one phase It can only be detected. In this case, it is necessary to take measures such as using the value detected last time again, estimating the value, intentionally changing the energization time, etc., but causes problems such as inaccurate position detection and distortion of the current waveform. (Low noise, low vibration, weak start-up effect).
[0060]
The following describes how to deal with this. In three-phase modulation, the phase voltage does not change even if the energization is added or subtracted at the same value for each phase. As an example, in FIG. 5, adding 20% to each phase increases the neutral point voltage (the sum of the terminal voltages of each phase by 3) by 20%. Since the phase voltage is a value obtained by subtracting the neutral point voltage from the terminal voltage, 20% of the phase voltage is canceled out, which is the same as the phase voltage before adding. The same applies even if minus.
[0061]
Therefore, the following can be dealt with.
[0062]
FIG. 16 shows an example. The method described below is referred to as P method 1. Among the three-phase energizing times, the maximum energizing time is A, the intermediate energizing time is B, and the minimum energizing time is C. A half of the difference between the maximum energizing time A and the intermediate energizing time B [(AB) / 2] is defined as α. The half [(B−C) / 2] of the difference between the intermediate energization time B and the minimum energization time C is defined as β. Further, the minimum time required for the current sensor 6 to detect the current is δ.
[0063]
FIG. 16A shows a case where the phase is 30 degrees at the maximum modulation of 100%. In this case, α <δ (α = 0) and β ≧ δ (δ = A / 2 = B / 2).
[0064]
In FIG. 16B, 2δ is added to the latter half of the energization period to the maximum energization time (W phase). Thereby, the current detection time of 2δ is secured, and the W-phase current can be detected. The same applies even if added in the first half of the energization period.
[0065]
In FIG. 16C, 2δ is added equally to the first half and the second half of the energization period to the intermediate energization time (U phase) and the minimum energization time (V phase). Thus, in the latter half of the energization period, the W-phase current detection time 2δ in FIG. 16B is reduced to δ, but the required current detection minimum time δ can be secured, so that the W-phase current detection is possible. In the first half of the energization period, the current detection time of δ is secured, and the U-phase current can be detected.
[0066]
Therefore, even when only one phase can be detected, W-phase and U-phase currents can be detected in addition to the V-phase. Thus, the position of the permanent magnet rotor can be determined. Further, since the same energizing time is applied to all three phases, there is no change in the three-phase modulation, and the current waveform does not become distorted. As a result, a small and lightweight motor drive device having low noise, low vibration, high start-up performance, and high reliability can be obtained.
In the above description, the phase is specified to be 30 degrees at which the energization time matches, but the same applies to around 30 degrees at which the energization time approximates. As long as δ is equal to or longer than the minimum time required for current detection.
[0067]
(Embodiment 2)
FIG. 17 shows another method of coping with the case where the energization times match. This is referred to as M method 1.
[0068]
FIG. 17A shows a case where the phase is 90 degrees at the maximum modulation of 100%. In this case, α ≧ δ and β <δ (δ = 0).
[0069]
In FIG. 17B, 2δ is reduced in the latter half of the energization period from the minimum energization time (W phase). Thereby, the current detection time of 2δ is secured, and the W-phase current can be detected. The same applies even if the power is reduced in the first half of the energization period.
[0070]
In FIG. 17C, 2δ is uniformly reduced in the first half and the second half of the energization period from the maximum energization time (U phase) and the intermediate energization time (V phase). Thereby, in the latter half of the energization period, the W-phase current detection time 2δ in FIG. 17B is reduced to δ, but the minimum current detection required time δ can be secured, so that the W-phase current detection is possible. In the first half of the energization period, the current detection time of δ is secured, and the V-phase current can be detected.
[0071]
Therefore, even when only one phase can be detected, the W-phase and V-phase currents can be detected in addition to the U-phase. There is 100% modulation, and it is possible to cope with a case where the energization time cannot be added. Thus, the position of the permanent magnet rotor can be determined. In addition, since the same energization time is reduced for all three phases, there is no change in the three-phase modulation and the current waveform is not distorted. As a result, a small and lightweight motor drive device having low noise, low vibration, high start-up performance, and high reliability can be obtained.
In the above description, the phase is specified to be 90 degrees at which the energization time matches, but the same applies to around 90 degrees at which the energization time approximates. As long as δ is equal to or longer than the minimum time required for current detection.
[0072]
The use of the P method 1 and the M method 1 will be described separately. At a phase of 30 degrees, the M method 1 cannot be applied because the conduction time of one phase (V phase) is 0%. Further, at the phase of 90 degrees, the P method 1 cannot be applied because the conduction time of one phase (U phase) is 100%. Therefore, when α <δ, β ≧ δ, the P method 1 can be used, and when α ≧ δ, β <δ, the M method 1 can be used.
[0073]
(Embodiment 3)
FIG. 18 shows another application example of the P scheme 1.
[0074]
FIG. 18A shows a case where the phase is 75 degrees at the maximum modulation of 10%. In this case, α <δ and β <δ, and it is impossible to detect current for one phase.
[0075]
In FIG. 18B, 2δ is added to the maximum energization time (U phase) in the latter half of the energization period. Thereby, the current detection time of 2δ + α is secured, and the U-phase current can be detected. The same applies even if added in the first half of the energization period.
[0076]
In FIG. 18C, 2δ is equally added to the first half and the second half of the energization period for the intermediate energization time (W phase) and the minimum energization time (V phase). Thus, in the latter half of the energization period, the U-phase current detection time 2δ + α in FIG. 18B is reduced to δ + α, but the required current detection minimum time δ can be secured, so that the U-phase current detection is possible. However, the time of δ cannot be secured in the first half of the energization period.
[0077]
Therefore, under the conditions of α <δ and β <δ, the P method 1 does not function. The same applies to M method 1.
[0078]
FIG. 19 shows a method for dealing with this case. This is referred to as P method 2.
[0079]
FIG. 19A shows a case where the phase is 75 degrees at the maximum modulation of 10%. In this case, α <δ and β <δ, but α + β ≧ δ and α ≧ β.
[0080]
In FIG. 19B, 2α is equally added to the first half and the second half of the energization period during the middle energization time (W phase). As a result, the current detection time α + β ≧ δ is secured in both the first half of the energization period and the second half of the energization period, and the V-phase current can be detected.
[0081]
In FIG. 19C, 2α is added to the latter half of the energization period to the maximum energization time (U phase) and the minimum energization time (V phase). Thus, in the latter half of the energization period, the V-phase current detection time α + β ≧ δ in FIG. 19B becomes the U-phase current detection time α + β ≧ δ, and the U-phase current can be detected. In the first half of the energization period, the V-phase current detection time α + β ≧ δ is maintained, and the V-phase current can be detected. The same applies even if added in the first half of the energization period.
[0082]
Therefore, even when the detection for one phase is impossible, the current for two phases (U-phase and V-phase in this example) can be detected. Thus, the position of the permanent magnet rotor can be determined. Further, since the same energizing time is applied to all three phases, there is no change in the three-phase modulation, and the current waveform does not become distorted. As a result, a small and lightweight motor drive device having low noise, low vibration, high start-up performance, and high reliability can be obtained.
The additional energizing time may be 2α or more. It may be 2δ. When 2α is added to the maximum energizing time (U phase) and the minimum energizing time (V phase), they may be added in the first half of the energizing period and the latter half of the energizing period, respectively. Since this method is complicated and requires a long processing time, the carrier frequency may be reduced to increase the carrier period to secure the processing time. (This method is necessary when the modulation is low. Even if lowered, the resolution by the carrier is secured.) This method is also applicable under the application conditions of the P method 1.
[0083]
(Embodiment 4)
FIG. 20 shows another corresponding method when α <δ and β <δ in the third embodiment. This is referred to as M method 2.
[0084]
FIG. 20A shows a case where the phase is 45 degrees at the maximum modulation of 10%. In this case, α <δ and β <δ, but α + β ≧ δ and α <β.
[0085]
In FIG. 20B, 2β is uniformly reduced in the first half and the second half of the energization period from the intermediate energization time (W phase). As a result, the current detection time α + β ≧ δ is secured in both the first half of the energization period and the second half of the energization period, and the U-phase current can be detected.
[0086]
In FIG. 20C, 2β is reduced in the latter half of the energization period from the maximum energization time (U phase) and the minimum energization time (V phase). Thereby, in the latter half of the energization period, the U-phase current detection time α + β ≧ δ in FIG. 20B becomes the V-phase current detection time α + β ≧ δ, and the V-phase current detection becomes possible. In the first half of the energization period, the U-phase current detection time α + β ≧ δ is maintained, and the U-phase current can be detected. The same applies even if added in the first half of the energization period.
[0087]
Therefore, even when the detection for one phase is impossible, the current for two phases (U-phase and V-phase in this example) can be detected. Thus, the position of the permanent magnet rotor can be determined. Further, since the same energizing time is applied to all three phases, there is no change in the three-phase modulation, and the current waveform does not become distorted. As a result, a small and lightweight motor drive device having low noise, low vibration, high start-up performance, and high reliability can be obtained.
The reduced energization time may be 2β or more. It may be 2δ. When 2β is reduced by the maximum energizing time (U phase) and the minimum energizing time (V phase), the reduction may be performed in the first half of the energizing period and the latter half of the energizing period, respectively. Since this method is complicated and requires a long processing time, the carrier frequency may be reduced to increase the carrier period to secure the processing time. (This method is necessary when the modulation is low. Even if lowered, the resolution by the carrier is secured.) This method is also applicable under the application conditions of the M method 1.
[0088]
(Embodiment 5)
In FIG. 15 (5% modulation), the sum of α and β is also smaller than δ. In this case, P method 1, P method 2, M method 1, and M method 2 cannot cope.
[0089]
FIG. 21 shows a method for dealing with this case. This method is referred to as P method 3.
[0090]
FIG. 21A shows a case where the phase is 75 degrees at the maximum modulation of 10%. Originally, the case where the phase is 75 degrees at the maximum modulation of 5% should be shown. However, since α and β are so small that it is difficult to show them in the figure, they are substituted. Note that α + β <δ.
[0091]
In FIG. 21B, 2δ is added to the latter half of the energization period to the maximum energization time (U phase). Also, 2δ is added to the first half of the energization period for the intermediate energization time (W phase). As a result, the current detection time 2δ + α ≧ δ is secured in the latter half of the energization period, and the U-phase current can be detected. The current detection time 2δ−α ≧ δ is secured in the first half of the energization period, and the W-phase current can be detected. The same applies if the addition is performed in the first half of the energization period and the addition is performed in the latter half of the energization period.
[0092]
In FIG. 21C, 2δ is added equally to the first half and the second half of the energization period to the minimum energization time (V phase). Thus, in the latter half of the energization period, the U-phase current detection time 2δ + α ≧ 2δ in FIG. 21B is δ + α + β, which is δ or more, and the U-phase current can be detected. In the first half of the energization period, the W-phase current detection time 2δ−α ≧ δ in FIG. 21B is δ + β, which is δ or more, and W-phase current detection is possible.
[0093]
Therefore, even in the case of α + β <δ, currents of two phases (U-phase and W-phase in this example) can be detected. Thus, the position of the permanent magnet rotor can be determined. Further, since the same energizing time is applied to all three phases, there is no change in the three-phase modulation, and the current waveform does not become distorted. As a result, a small and lightweight motor drive device having low noise, low vibration, high start-up performance, and high reliability can be obtained.
The additional energization time may be 2δ or more. Since this method is complicated and requires a long processing time, the carrier frequency may be reduced to increase the carrier period to secure the processing time. (This method is necessary when the modulation is low. Even if lowered, the resolution by the carrier is secured.) This method is also applicable under the application conditions of P method 1 and P method 2.
[0094]
(Embodiment 6)
FIG. 22 shows another correspondence method when α + β <δ in the fifth embodiment. This is referred to as M method 3.
[0095]
FIG. 22A shows a case where the phase is 45 degrees at the maximum modulation of 10%. Originally, the case where the phase is 45 degrees at the maximum modulation of 5% should be shown. However, since α and β are so small that it is difficult to show them in the figure, they are substituted. Note that α + β <δ.
[0096]
In FIG. 22B, 2δ is reduced in the latter half of the energization period from the minimum energization time (V phase). In addition, 2δ is reduced in the first half of the energization period from the intermediate energization time (W phase). As a result, the current detection time 2δ + β ≧ δ is secured in the latter half of the energization period, and the V-phase current can be detected. The current detection time 2δ−β ≧ δ is secured in the first half of the energization period, and the W-phase current can be detected. The same is true even if the reduction is performed in the first half of the power supply period and the reduction in the latter half of the power supply period.
[0097]
In FIG. 22C, 2δ is uniformly reduced from the maximum energization time (U phase) in the first half and the second half of the energization period. Thus, in the latter half of the energization period, the V-phase current detection time 2δ + β ≧ δ in FIG. 22B is δ + α + β, which is δ or more, and V-phase current detection is possible. In the first half of the energization period, the W-phase current detection time 2δ−β ≧ δ in FIG. 22B is δ + α, but is δ or more, and W-phase current detection is possible.
[0098]
Therefore, even in the case of α + β <δ, currents for two phases (V-phase and W-phase in this example) can be detected. Thus, the position of the permanent magnet rotor can be determined. Further, since the same energizing time is applied to all three phases, there is no change in the three-phase modulation, and the current waveform does not become distorted. As a result, a small and lightweight motor drive device having low noise, low vibration, high start-up performance, and high reliability can be obtained.
The reduced energization time may be 2δ or more. Since this method is complicated and requires a long processing time, the carrier frequency may be reduced to increase the carrier period to secure the processing time. (This method is necessary when the modulation is low. Even if lowered, the resolution by the carrier is secured.) This method is also applicable under the application conditions of the M method 1 and the M method 2.
[0099]
(Embodiment 7)
FIG. 23 shows a diagram in which the motor driving device 20 is attached to the left side of the electric compressor 40 in close contact. The compression mechanism 28, the motor 31 and the like are installed in the metal housing 32. The refrigerant is sucked through the suction port 33 and is compressed by the compression mechanism 28 (the scroll in this example) being driven by the motor 31.
[0100]
The compressed refrigerant passes through (cools) the motor 31 and is discharged from the discharge port 34. The terminal 39 internally connected to the winding of the motor 31 is connected to the motor driving device 20.
[0101]
The motor drive device 20 uses a case 30 so as to be attached to the electric compressor 40. The inverter circuit section 37 serving as a heat source dissipates heat to the metal casing 32 of the electric compressor 40 via the case 30 (the refrigerant inside the electric compressor 40 via the metal casing 32). Cooled in).
[0102]
The terminal 39 is connected to the output of the inverter circuit 37. The connection line 36 includes a power supply line to the battery 1 and a control signal line to the air conditioner controller. By employing concentrated winding for the winding of the motor 31, the length in the lateral direction can be reduced as compared with distributed winding. Since the concentrated winding has a large inductance, the return time to the diode becomes longer when 120 ° conduction is performed, and the position detection is difficult and control is difficult. However, in the sine wave drive, the position can be controlled by the current and thus can be controlled.
[0103]
In such an electric compressor integrated with a motor driving device, the motor driving device 20 needs to be small and strong against vibration. It is suitable as an embodiment of the present invention.
[0104]
Preferably, three-phase modulation is used to reduce vibration. The sinusoidal current becomes smoother, thus reducing vibration.
[0105]
【The invention's effect】
As is apparent from the above, the present invention detects the position of the magnet rotor by using the current sensor for detecting the power supply current also for the current detection of the stator winding. Sine wave drive is possible without adding a current sensor for phase current detection, and a phase shift circuit and a comparison circuit in the conventional 120-degree conduction is not required, and the number of components is reduced, so that low noise and low vibration are achieved. There is an effect that a small, lightweight, and highly reliable motor drive device with high startability can be obtained.
[0106]
In addition, the present invention adds or subtracts the same energizing time during the energizing period within the carrier cycle of each phase, and the addition or subtraction is performed by distributing each phase into the first half or the second half or the first and second half of the carrier cycle. The current sensor detects the current flowing through the stator winding by using a current sensor. According to this configuration, the value detected last time is used again, estimated, or the energization time is intentionally changed. No effect is required, and there is an effect that the position detection does not become inaccurate and a problem such as distortion of the current waveform does not occur.
[0107]
Further, the present invention has the effect of being small in size, strong in vibration resistance, capable of adopting concentrated winding for the motor winding, and capable of shortening the lateral length of the motor-integrated electric compressor.
[Brief description of the drawings]
FIG. 1 is an electric circuit diagram showing a first embodiment of the present invention.
FIG. 2 is an explanatory diagram of an induced voltage detection method in sine wave driving.
FIG. 3 is a waveform diagram showing voltage and current of a sensorless DC brushless motor.
FIG. 4 is a waveform chart showing modulation of each phase at a maximum modulation of 100% of three-phase modulation.
FIG. 5 is a waveform diagram showing modulation of each phase at a maximum modulation of 50% of three-phase modulation.
FIG. 6 is a waveform chart showing modulation of each phase at a maximum modulation of 10% of three-phase modulation.
FIG. 7 is an energization timing chart showing a phase current detection method according to the first embodiment of the present invention.
FIG. 8 is an electric circuit diagram showing a current path at the same energization timing (a).
FIG. 9 is an electric circuit diagram showing a current path at the same energization timing (b).
FIG. 10 is an electric circuit diagram showing a current path at the same energization timing (c).
FIG. 11 is an electric circuit diagram showing a current path at the same energization timing (d).
FIG. 12 is an explanatory diagram showing energization of the upper arm for each phase of 100% maximum modulation of three-phase modulation.
FIG. 13 is an explanatory diagram showing energization of the upper arm in each phase of 50% of maximum modulation in three-phase modulation.
FIG. 14 is an explanatory diagram showing energization of the upper arm for each phase of 10% of maximum modulation of three-phase modulation.
FIG. 15 is an explanatory diagram showing energization of the upper arm for each phase of 5% of maximum modulation of three-phase modulation.
FIG. 16 is an explanatory diagram showing phase current detection of three-phase modulation according to the first embodiment of the present invention.
FIG. 17 is an explanatory diagram showing phase current detection of three-phase modulation according to the second embodiment of the present invention.
FIG. 18 is an explanatory diagram showing a problem of phase current detection according to the third embodiment of the present invention.
FIG. 19 is an explanatory diagram showing phase current detection of three-phase modulation according to the third embodiment of the present invention.
FIG. 20 is an explanatory diagram showing phase current detection of three-phase modulation according to the fourth embodiment of the present invention.
FIG. 21 is an explanatory diagram showing phase current detection of three-phase modulation according to the fifth embodiment of the present invention.
FIG. 22 is an explanatory diagram showing phase current detection of three-phase modulation according to the sixth embodiment of the present invention.
FIG. 23 is a cross-sectional view of a motor drive unit-integrated electric compressor showing a seventh embodiment of the present invention.
FIG. 24 is a configuration diagram of a vehicle air conditioner equipped with a conventional electric compressor.
FIG. 25 is an electric circuit diagram for 120 ° conduction drive;
FIG. 26 is an electric circuit diagram for driving a sine wave provided with a current sensor for detecting in-phase current.
[Explanation of symbols]
1 Battery
2 Switching element
3 diode
4 Stator winding
5 Magnet rotor
6 Current sensor
7 Control circuit
20 Motor drive
30 Integrated case for motor drive
31 Motor part
40 Electric compressor

Claims (9)

An inverter circuit that outputs a sine-wave AC current to a sensorless DC brushless motor by switching a DC voltage of a DC power supply, and a current sensor that detects a current between the DC power supply and the inverter circuit. The same energization time is added or subtracted to the energization period in the carrier cycle of each phase, and the addition or subtraction is selected for each phase in the first half or the second half or the first half and the second half in the carrier cycle. A motor drive device that determines a position of the permanent magnet rotor by detecting a current flowing through the stator winding by the current sensor, and controls switching of the inverter circuit. 2. The motor drive device according to claim 1, wherein the phase having the largest energization period in the carrier cycle is added to the first or second half of the carrier cycle, and the other phases are equally divided and added to the first and second half of the carrier cycle. 2. The motor drive device according to claim 1, wherein a phase having a minimum energization period in the carrier cycle is subtracted in the first half or the second half of the carrier cycle, and the other phases are equally divided and subtracted in the first and second half of the carrier cycle. 2. The motor drive according to claim 1, wherein a phase having a maximum and a minimum energization period in the carrier cycle is added to the first half or the second half of the carrier cycle, and an intermediate phase is equally divided and added to the first half and the second half of the carrier cycle. apparatus. 2. The motor drive according to claim 1, wherein a phase having a maximum and a minimum energization period in the carrier cycle is subtracted in the first or second half of the carrier cycle, and an intermediate phase is equally divided and subtracted in the first and second half of the carrier cycle. apparatus. The phase with the largest energization period in the carrier cycle is added to the first or second half of the carrier cycle, the middle phase is added in a half period different from the largest phase, and the smallest phase is added to the first half in the carrier cycle. The motor drive device according to claim 1, wherein the motor drive device is equally divided and added in the latter half. The phase with the middle conduction period in the carrier cycle is subtracted in the first half or the second half of the carrier cycle, the smallest phase is subtracted in a half period different from the middle phase, and the largest phase is the first half in the carrier cycle. 2. The motor drive device according to claim 1, wherein the motor drive device is equally divided and subtracted in the latter half. The motor drive device according to any one of claims 1 to 7, which is mounted on an electric compressor including a sensorless DC brushless motor. The motor drive device according to any one of claims 1 to 8, which is mounted on a vehicle air conditioner.

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