JP3362150B2 - Brushless DC motor driving method and device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless DC motor driving method and an apparatus thereof, and more particularly, to a brushless DC motor driving method and an apparatus thereof for driving a brushless DC motor using an inverter.

[0002]

2. Description of the Related Art As a motor having a higher efficiency than an AC motor, by installing a permanent magnet in the rotor instead of the rotor winding, a secondary copper loss caused by a current flowing through the rotor winding. There is known a brushless DC motor that eliminates the above. It is known that this brushless DC motor has a particularly large efficiency improvement effect in the small and medium capacity range of several tens kW or less as compared with the AC motor.

In the brushless DC motor drive system of this capacity range, a voltage type inverter or a current control type inverter is used as an inverter for driving the brushless DC motor. Here, the current control type inverter has the same main circuit configuration as the voltage type inverter, and controls the inverter so that the motor current has a desired value.

A system for driving a brushless DC motor using the voltage source inverter is mainly used in an air conditioner,
It is mounted on equipment that requires large power consumption (high efficiency) and is mass-produced, such as an electric vacuum cleaner and an electric washing machine. Therefore, as the waveform control of the inverter unit, a 120 ° energization waveform is adopted from the viewpoint of easiness of control, and an inexpensive system having a simple configuration is adopted (“Micro”).
computer-Controlled Brush
less Motor without a Shaft
-Mounted Position Senso
r ", T. Endo et al., IPEC-Tokyo'83,
pp. 1477-1488, 1983, "PM Br.
uless Motor Drives: A Se
lf-Commutating System wit
hout Rotor-Position Senso
rs ", P. Ferraris et al., Proceedin
gsof the Ninth Annual Sym
Posium-Incremental Motion
Control Systems and Devi
ces, pp. 305-312, 1980). Further, as a configuration for detecting the magnetic pole position of the brushless DC motor, from the viewpoint of cost reduction, an expensive rotational position sensor such as a rotary encoder is not used, but motor induced voltage detection (fundamental wave component of motor induced voltage or 3 A magnetic pole position is detected by detecting the next harmonic component or a magnetic pole position detection sensor having a simple structure using a Hall element or the like is adopted. The system for driving a brushless DC motor using the current control type inverter is mainly applied to machine tools, servo motors for industrial robots, etc. where high-speed torque response and low torque ripple are the most important requirements. To be done.

In this system, brushless DC
Focusing on the fact that the motor current and torque are functions of rotation position and in a proportional relationship, a closed loop configuration is used in which the output voltage of the inverter is determined (calculated) by the control circuit so that the current waveform has the desired waveform. is doing. Therefore, a precise sensor for detecting the rotational position of the motor, a current detector for precisely controlling the motor current, and a controller capable of high-speed processing are adopted, which is an expensive system configuration. Further, since the inverter is instantaneously controlled according to the state of the motor, the output voltage of the inverter constantly changes.

[0006]

When the magnetic pole position detection sensor using the above hall element or the like is adopted, an accurate magnetic pole position detection signal can be obtained regardless of the control system, so that AV (audio / visual) is used. ), It is widely used in applications such as computer peripherals. However, in applications where the ambient temperature of the motor is high, such as in compressors and electric vehicles, considering the temperature characteristics of the element, element cooling is required to obtain a practical magnetic pole position detection signal. However, there is an inconvenience that the structure is complicated as a whole and the cost is increased.

When the magnetic pole position detection sensor for detecting the fundamental wave component of the motor induced voltage is adopted from the inverter output terminal, the above-mentioned inconvenience can be solved, but the fundamental wave component of the motor induced voltage is detected. Requires a control mode in which a motor current does not flow, which has a disadvantage that the control range and specifications of the motor are restricted.

When a magnetic pole position detection sensor for detecting the third harmonic component of the motor induced voltage from the inverter output terminal is adopted, any of the above inconveniences can be solved. However, in reality, there is an imbalance in the electric circuit constants of the brushless DC motor drive system, and due to this imbalance, noise components are mixed in the magnetic pole position detection signal, and sufficient performance cannot be obtained. . This inconvenience is caused by the "PM Brushless Motor Dri" described above.
ves: A Self-Commutating Sy
Stem withoutout Rotor-Positi
on Sensors ", but no solution is described.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and eliminates the influence of the noise component of the magnetic pole position detection signal due to the imbalance of the electric circuit constants of the brushless DC motor drive system, or A brushless DC motor drive control method capable of suppressing and improving the stability of an inverter control system and greatly expanding an operating range in which a brushless DC motor can be driven without stopping in a system in which a load changes suddenly, and The purpose is to provide the device.

[0010]

A brushless D according to claim 1.
In the C motor driving method, a first neutral point voltage is obtained by connecting the other end of a resistor, one end of which is connected to the output terminal of each phase of the inverter, to each other, and One end of the stator winding is connected to each other to obtain a second neutral point voltage, and the magnetic pole of the rotor of the brushless DC motor is based on the difference between the first neutral point voltage and the second neutral point voltage. A brushless DC motor driving method of detecting a position and supplying an output from an inverter controlled based on the detected magnetic pole position to a brushless DC motor to drive the brushless DC motor, wherein an output waveform of the inverter is smoothed. This is a method of controlling the inverter to change it. However, in this specification, “controlling the inverter so as to smoothly change the output waveform of the inverter” means that each phase command current pair of the current control type inverter of FIG. 4 is illustrated in FIG. "The output command value of the inverter is positive
It is used as a term that means "controlling the inverter while using an intermediate value as an output command value in the process of changing from a predetermined value on the negative side, 0 to any other value."

A brushless DC motor driving method according to a second aspect of the present invention is a method of controlling an inverter so as to smoothly change a voltage waveform of the inverter. The brushless DC motor driving method according to claim 3 is a method of controlling the inverter so as to smoothly change the current waveform of the inverter. The brushless DC motor driving method of claim 4 is a method of controlling the inverter so as to change the output waveform of the inverter into a sine wave shape.

A brushless DC motor driving method according to a fifth aspect is a method of controlling the inverter so as to change the output waveform of the inverter so as to suppress the speed fluctuation of the brushless DC motor during one rotation. Brushless D according to claim 6.
The C motor drive device obtains a first neutral point voltage by connecting the other end of a resistor, one end of which is connected to the output terminal of each phase of the inverter, to the first neutral point voltage, and One end of the stator winding is connected to each other to obtain a second neutral point voltage, and the magnetic pole of the rotor of the brushless DC motor is based on the difference between the first neutral point voltage and the second neutral point voltage. A brushless DC motor drive device that detects a position and supplies an output from an inverter that is controlled based on the detected magnetic pole position to a brushless DC motor to drive the brushless DC motor. The output waveform of the inverter is smoothed. It includes inverter control means for controlling the inverter to vary.

In the brushless DC motor drive device according to the seventh aspect, as the inverter control means, one which controls the inverter so as to smoothly change the voltage waveform of the inverter is adopted. In the brushless DC motor drive device according to the eighth aspect, as the inverter control means, one that controls the inverter so as to smoothly change the current waveform of the inverter is adopted.

In the brushless DC motor drive device according to the ninth aspect, as the inverter control means, one that controls the inverter so as to change the output waveform of the inverter into a sine wave shape is adopted. The brushless DC motor driving device according to claim 10 obtains a first neutral point voltage by connecting the other ends of the resistors, one end of which is connected to the output terminals of each phase of the inverter, to each other, and the brushless DC motor. A brushless DC motor based on a difference between a first neutral point voltage and a second neutral point voltage by connecting one ends of stator windings of respective phases of the motor to each other to obtain a second neutral point voltage. Is a brushless DC motor driving device for detecting a magnetic pole position of a rotor of the rotor and supplying an output from an inverter controlled based on the detected magnetic pole position to a brushless DC motor to drive the brushless DC motor. An energization width setting means for setting the energization width to a predetermined width of less than 180 °, and a differential voltage supply interruption means for interrupting the supply of the differential voltage to the rotor position detection means corresponding to the non-energization width of the inverter. There.

The brushless DC motor drive device of claim 11 employs, as the inverter control means, a device for controlling the inverter so as to change the output waveform of the inverter so as to suppress the speed fluctuation of the brushless DC motor during one rotation. ing.

[0016]

According to the brushless DC motor driving method of the first aspect, the first neutral point voltage can be obtained by connecting the other ends of the resistors, one end of which is connected to the output terminals of each phase of the inverter, to each other. At the same time, one end of each stator winding of each phase of the brushless DC motor is connected to each other to obtain a second neutral point voltage, and a difference between the first neutral point voltage and the second neutral point voltage is obtained. The brushless DC motor is detected based on the magnetic pole position of the brushless DC motor based on the detected magnetic pole position, and the output from the inverter controlled based on the detected magnetic pole position is supplied to the brushless DC motor.
When driving the C motor, the inverter is controlled so as to smoothly change the output waveform of the inverter, so that there is no point where the output waveform of the inverter changes abruptly, and the magnetic pole caused by the abrupt change of the output waveform is eliminated. The disturbance of the position detection signal can be prevented, and the brushless DC motor can be stably driven regardless of the imbalance of the electric circuit constants. As a result, the operating range can be greatly expanded even in a system in which the load changes abruptly.

According to the brushless DC motor driving method of the second aspect, since the inverter is controlled so as to smoothly change the voltage waveform of the inverter, the same operation as that of the first aspect can be achieved. According to the brushless DC motor driving method of the third aspect, since the inverter is controlled so as to smoothly change the current waveform of the inverter, the same operation as that of the first aspect can be achieved.

According to the brushless DC motor driving method of the fourth aspect, since the inverter is controlled so as to change the output waveform of the inverter into a sine wave shape, the same operation as that of the first aspect can be achieved. According to the brushless DC motor driving method of claim 5, since the inverter is controlled to change the output waveform of the inverter so as to suppress the speed variation of the brushless DC motor during one rotation, the speed variation of the brushless DC motor. Can be eliminated or significantly suppressed, and as a result, the load can be smoothly driven, and the same operation as that of any one of claims 1 to 4 can be achieved.

According to another aspect of the brushless DC motor drive device of the present invention, the other end of the resistor, one end of which is connected to the output terminal of each phase of the inverter, is connected to each other to generate the first neutral point voltage. At the same time, one end of each stator winding of each phase of the brushless DC motor is connected to each other to obtain a second neutral point voltage, and a difference between the first neutral point voltage and the second neutral point voltage is obtained. An output waveform of the inverter when the brushless DC motor is driven based on the detected magnetic pole position of the rotor of the brushless DC motor and the output from the inverter controlled based on the detected magnetic pole position is supplied to the brushless DC motor. Inverter is controlled by the inverter control means in order to change smoothly. Therefore, there is no point where the output waveform of the inverter changes abruptly, the disturbance of the magnetic pole position detection signal due to the abrupt change of the output waveform is prevented, and the brushless D
The C motor can be driven stably. As a result, the operating range can be greatly expanded even in a system in which the load changes abruptly.

According to the brushless DC motor drive device of the seventh aspect, since the inverter control means for controlling the inverter to smoothly change the voltage waveform of the inverter is adopted, the same operation as the sixth aspect is achieved. Can be achieved. In the brushless DC motor drive device according to the eighth aspect, since the inverter control means that controls the inverter to smoothly change the current waveform of the inverter is adopted, the same operation as the sixth aspect is achieved. be able to.

In the brushless DC motor drive device according to the ninth aspect, since the inverter control means for controlling the inverter so as to change the output waveform of the inverter into a sine wave is adopted, the same as the sixth aspect. The action can be achieved. In the brushless DC motor drive device according to claim 10, the other end of the resistor having one end connected to the output terminal of each phase of the inverter is connected to each other to obtain the first neutral point voltage, One end of each stator winding of each phase of the brushless DC motor is connected to each other to obtain a second neutral point voltage, and the brushless is obtained based on the difference between the first neutral point voltage and the second neutral point voltage. When the magnetic pole position of the rotor of the DC motor is detected, and the output from the inverter controlled based on the detected magnetic pole position is supplied to the brushless DC motor to drive the brushless DC motor, the energization width setting means is used to drive the inverter. The conduction width can be set to a predetermined width of less than 180 °, and the supply of the difference voltage to the rotor position detecting means can be interrupted by the difference voltage supply interrupting means in correspondence with the non-energization width of the inverter. Therefore, it is possible to reliably prevent the noise caused by the abrupt change in the output waveform of the inverter from being supplied to the rotor position detecting means, and to accurately detect the magnetic pole position of the rotor based on the difference voltage. can do. As a result, the brushless DC motor can be stably driven regardless of the imbalance of electric circuit constants, and the operating range can be greatly expanded even in a system in which the load changes abruptly.

According to another aspect of the brushless DC motor drive device of the present invention, the inverter control means controls the inverter so as to change the output waveform of the inverter so as to suppress the speed fluctuation of the brushless DC motor during one rotation. Since it is adopted, the speed fluctuation of the brushless DC motor can be eliminated or greatly suppressed, and as a result, the load can be smoothly driven, and the same as in any one of claims 6 to 10. The action of can be achieved.

Further details will be described. In driving a brushless DC motor with an inverter, the other end of a resistor, one end of which is connected to the output terminal of each phase of the inverter, is connected to each other to obtain a first neutral point voltage, and a brushless One end of the stator winding of each phase of the DC motor is connected to each other to obtain a second neutral point voltage, and the difference between the first neutral point voltage and the second neutral point voltage is integrated and integrated. When the magnetic pole position of the rotor of the brushless DC motor is detected by supplying the signal to the zero cross comparator,
As shown in FIG. 24, which shows the motor current and the integral signal, the integral signal may be distorted when the current change is abrupt, the magnetic pole position detection signal may be disturbed, and in the worst case, the brushless DC motor may lose synchronization. FIG. 24 shows the case where the energization width is 120 °, but when the energization width is set to 150 ° and 180 °,
Since the current change becomes less steep as the energization width increases, the distortion of the integrated signal becomes smaller as shown in FIG. 25 and FIG. 26 for the motor current and the integrated signal, respectively. However, the disturbance of the integrated signal cannot be completely eliminated. Therefore, the integrated signal may become very small depending on the load or the inverter output voltage, the magnetic pole position detection signal may be disturbed, and the brushless DC motor may lose synchronization. Note that FIG.
The change in the amplitude of the motor current in FIGS. 4, 25 and 26 is caused by the torque control.

Further, the energization width is 120 °, 150 °, 18
Integral input (signal before integration) when set to 0 °
27, FIG. 28, and FIG. 2 for the integrated output and the integrated output (signal after integration).
9 respectively. From these figures, it is understood that the integrated output is distorted by the noise of the integrated input, and the noise becomes smaller as the conduction width becomes wider. The inventor of the present invention pays attention to the fact that the integrated signal is distorted when the current change is steep, and the distortion of the integrated signal can be eliminated by controlling the current waveform so as to smoothly change the current waveform. The inventors of the present invention completed the present invention by finding that the position detection signal can be stably output.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing an embodiment of a brushless DC motor drive control device of the present invention, in which an output voltage of an inverter 2 is applied to a brushless DC motor 3. And brushless DC motor 3
Of the second neutral point voltage obtained by Y-connecting the stator winding of each phase of (1) and the first neutral point voltage obtained by Y-connecting the resistor between the output terminals of each phase of the inverter 2. An output signal from the motor position detection circuit 4 that receives the differential voltage is supplied to the control circuit 5, and the control circuit 5 sets the electrical energization width to a predetermined width of, for example, more than 120 ° and 180 ° or less. Therefore, the control command is generated and supplied to the inverter 2.

Therefore, the motor position detection circuit 4 obtains the magnetic pole position detection signal of the motor rotor based on the voltage difference between the neutral point voltages, and the control circuit 5 generates a control command based on the magnetic pole position detection signal. Set the switch (not shown) of the inverter 2 to, for example, over 120 ° and 180 °
Control is performed so that the following predetermined energization width is achieved. FIG. 2 is a diagram schematically showing the structure of a brushless DC motor having a surface magnet structure, in which a permanent magnet 3b is mounted at a predetermined position on the surface of the rotor 3a. Further, the stator 3c has a large number of slots 3d around which a stator winding (not shown) is wound.
The d-axis indicated by the arrow in the figure is an axis that indicates the direction of the magnetic flux generated by the permanent magnet 3b, and the q-axis is an axis that is electrically deviated from the d-axis by 90 °.

FIG. 3 is a diagram schematically showing the structure of a brushless DC motor having an embedded magnet structure, in which a permanent magnet 3f is mounted on the surface of the rotor 3e so as not to be exposed. However, the non-magnetic body 3g is mounted between the adjacent permanent magnets 3f to prevent a magnetic flux short circuit between the adjacent permanent magnets 3f. Since the structure of the stator 3c is the same as that of the brushless DC motor of FIG. 2, the description will be omitted.

FIG. 4 is a diagram schematically showing the configuration of the brushless DC motor drive control device, and FIG. 5 is a diagram showing the internal configuration of the microprocessor 18 of FIG. Transistors 12u1 and 12
u2, 12v1, 12v2, 12w1, 12w2 are connected in series to form the inverter 12, and the connection point voltage between the switching transistors of each pair is brushless D.
C-motor 13 Y-connected stator winding 13 of each phase
It is applied to u, 13v, and 13w, respectively. And
Set the connection point voltage between the switching transistors of each pair to Y
It is also applied to the connected resistors 14u, 14v, 14w, respectively. The switching transistors 12u1,
Diodes 12u1d, 12u2d, 12v1d, 12v2d for protection are provided between collector-emitter terminals of 12u2, 12v1, 12v2, 12w1, 12w2, respectively.
12w1d and 12w2d are connected. In addition, 13e
Indicates the rotor of the brushless DC motor 13. The subscripts u, v, and w correspond to the u phase, v phase, and w phase of the brushless DC motor 13, respectively.

The Y-connected stator windings 13u, 13
The voltage at the neutral point 13d of v and 13w is supplied to the inverting input terminal of the amplifier 15 via the resistor 15a, and the voltage at the neutral point 14d of the Y-connected resistors 14u, 14v, and 14w is the non-inverted state of the amplifier 15 as it is. It is supplied to the input terminal. The resistor 15b is connected between the output terminal and the inverting input terminal of the amplifier 15 so that the amplifier 15 operates as a differential amplifier.

The output signal output from the output terminal of the amplifier 15 is supplied to the integrator 16 formed by connecting the resistor 16a and the capacitor 16b in series. The output signal from the integrator 16 (the voltage at the connection point between the resistor 16a and the capacitor 16b) is supplied to the non-inverting input terminal of the zero-cross comparator 17 whose voltage at the neutral point 13d is supplied to the inverting input terminal.

Therefore, the zero cross comparator 17
A magnetic pole position detection signal is output from the output terminal of. In other words, the differential amplifier, the integrator 16, and the zero-cross comparator 17 constitute a position detector that detects the magnetic pole position of the rotor 13e of the brushless DC motor 13.
The magnetic pole position detection signal output from the position detector is supplied to the external interrupt terminal of the microprocessor 18. In the microprocessor 18, interrupt processing for the phase correction timer 18a and the cycle measuring timer 18b is performed by the magnetic pole position detection signal supplied to the external interrupt terminal (interrupt processing 1 in FIG. 5).
See). Here, the phase correction timer 18a
A timer value is set by a timer value calculator 19a described later. The cycle measurement timer 18b uses the CPU 19 as the timer value.
Is supplied to the position signal cycle calculator 19b included in. The position signal cycle calculator 19b calculates a timer value per 1 ° of electrical angle based on the timer value corresponding to the electrical angle of 60 °, for example. The phase correction timer 18a supplies the countover signal to the mode selection unit 19c included in the CPU 19 to perform an interrupt process (see the interrupt process 2 in FIG. 5). The phase correction timer 18a also supplies a countover signal to the mode switching timer 18f to start the timer operation of the mode switching timer 18f. The timer value of the mode switching timer 18f is set by the timer value calculator 19a described later. Also, the mode switching timer 1
8f supplies a countover signal to the mode selection unit 19c included in the CPU 19 to perform an interrupt process (see interrupt process 3 in FIG. 5). The mode selection unit 19c reads the corresponding current pattern from the memory 18c and outputs it. In the CPU 19, the position signal cycle calculator 19b
Performs a calculation based on the timer value to output a position signal cycle signal, which is supplied to the timer value calculation unit 19a and the speed calculation unit 19e. The phase amount command is also supplied to the timer value calculation unit 19a, and the timer value to be set in the phase correction timer 18a is calculated based on the phase amount command and the position signal cycle signal from the position signal cycle calculation unit 19b. The speed calculator 19e calculates the current speed based on the position signal cycle signal from the position signal cycle calculator 19b, and supplies the current speed to the speed controller 19f. A speed command is also supplied to the speed command unit 19f, and a current amplitude command is output based on the speed command and the current speed from the speed calculation unit 19e. Then, the current pattern output from the mode selection unit 19c and the current amplitude command output from the speed command unit 19f are supplied to the multiplier 18d, and command current waveforms for three phases are output. This command current waveform is supplied to the switch selection circuit 20a together with the current detection waveform of each phase of the inverter 12. The voltage command output from the switch selection circuit 20a is supplied to the base drive circuit 20, and the base drive circuit 20
The switching transistors 12u1, 12u2, 1
The control signals to be supplied to the respective base terminals of 2v1, 12v2, 12w1 and 12w2 are output. In the above description, each component included in the CPU 19 only shows a functional part for achieving the corresponding function as a component, and these components can be clearly recognized inside the CPU 19. It does not exist in the state.
Here, the current pattern corresponding to the inverter mode is shown in Table 1. However, the current pattern represents the reference waveform of each phase current.

[0032]

[Table 1] Next, the operation of the brushless DC motor drive control device shown in FIG. 4 will be described with reference to the waveform chart shown in FIG.

Since the u-phase, v-phase, and w-phase induced voltages Eu, Ev, Ew of the brushless DC motor change with the phases sequentially shifted by 120 °, the signal VNM output from the amplifier 15 is shown in FIG. It changes as shown in (A), and the integrated waveform of this signal by the integrator 16 changes as shown in (B) in FIG. Then, by supplying the integrated waveform to the zero-cross comparator 17, a position signal that rises or falls at the zero-cross point of the integrated waveform is output as shown in (C) in FIG. Interrupt processing 1 is performed by the rising and falling of this position signal, and the phase correction timer 18a is started (see the starting point of the arrow in (D) in FIG. 9). Since the timer value calculation unit 19b sets the timer value in the phase correction timer 18a, the phase correction timer 18a counts over at the time when the timer operation is performed by the set timer value (end point of arrow (D) in FIG. 9). See}. Then, every time the phase correction timer 18a counts over, the interrupt process 2 is performed, and the mode selection unit 19c advances the inverter mode by one step. That is,
Inverter mode is "0""2""4""6""8"
"10", "0", "2" ... Are selected in this order. Also,
Each time the phase correction timer 18a counts over, the interrupt process 2 is performed and the mode switching timer 18f starts (see the starting point of the arrow in (E) in FIG. 9). Then, the mode switching timer 18f counts over (see FIG. 9).
The interrupt processing 3 is performed every time the middle (E) arrow end point is referred to}, and the mode selection unit 19c advances the inverter mode by one step. That is, the inverter mode is "1"
"3""5""7""9""11""1""3" ...
Are selected in this order. In addition, interrupt processing 2 and interrupt processing 3
Are generated alternately, the inverter mode is "0", "1", "2", "3", "4" as shown in (I) of FIG.
"5""6""7""8""9""10""11"
“0” “1” “2” “3” ...

Then, by advancing the inverter mode one step by the interruption processing 2 and the interruption processing 3, the command current waveform of each phase corresponding to each inverter mode is shown in FIG.
Medium, changes as shown in (F) to (H). As a result,
The brushless DC motor 13 can be driven, and the current command for each phase can be made substantially sinusoidal.

FIG. 10 is a diagram showing a motor current and an integrator output when the brushless DC motor is driven by using the brushless DC motor drive control device of FIG. By comparing the waveform of FIG. 10 with the waveform of FIG. 26, it is possible to surely prevent the inconvenience that the integrated signal becomes very small when this embodiment is adopted, and to eliminate the distortion of the integrated output. Therefore, it can be seen that the magnetic pole position detection signal can be stably output.

FIG. 6 is a flow chart for explaining the details of the above-mentioned interrupt processing 1, in which an external interrupt request is accepted at each of the rising edge and the falling edge of the magnetic pole position detection signal of the position detector. And step SP1
In step SP2, the value of the phase correction timer is calculated based on the external phase amount (phase correction angle) command and the position signal cycle obtained by the position signal cycle calculator 19b.
At, the correction timer value is set in the phase correction timer 18a, and the phase correction timer is started at step SP3. Then, in step SP4, the cycle measurement timer started in the previous interrupt processing 1 is stopped, and in step SP5 the cycle measurement timer value is read (stored). However, since the processing of steps SP4 and SP5 is processing for detecting the end of the edge of the position signal, after reading the period measurement timer value, step SP
At 6, the period measurement timer is immediately reset and started for the next period measurement. Then, the stored position signal cycle is calculated in step SP7 (for example, the number of counts per 1 electrical angle is calculated), and the current rotation speed of the brushless DC motor 13 is calculated based on the position signal cycle calculation result in step SP8. Calculate,
In step SP9, the speed control is performed so as to follow the speed command from the outside, the current amplitude command is output, and the process directly returns to the original process. Specifically, for example, the cycle measuring timer 18
If the count value corresponding to the interval of the magnetic pole position detection signal is 360 as a result of actual measurement by b, the magnetic pole position detection signal is detected 6 times during one electrical angle cycle, so the count value for one electrical angle cycle is It becomes 360 × 6 = 2160. Since this value 2160 corresponds to 360 °, 1 °
The count value of minutes becomes 2160/360 = 6. Here, if the phase amount command is 90 °, the count value (timer value) corresponding to the phase amount command is 6 × (90−60) = 18.
It becomes 0. Therefore, this value 180 is set in the phase correction timer 18a as a correction timer value, and the phase correction timer 18a is started.

FIG. 7 is a flow chart for explaining the processing contents of the interrupt processing 2 in detail. When the phase correction timer 18a started in the interrupt processing 1 counts over, the interrupt processing 2 is accepted. In step SP1, the inverter mode preset in the memory 18c is advanced by one step, in step SP2 a current pattern corresponding to the advanced inverter mode is output, and in step SP3 the timer value of the mode switching timer 18f is changed from the position signal period to the position signal cycle. Is calculated, the timer value obtained by the calculation is set in the mode switching timer 18f in step SP4, the mode switching timer 18f is started in step SP5, and the original processing is returned as it is.

FIG. 8 is a flow chart for explaining the processing contents of the interrupt processing 3 in detail, and the interrupt processing 3 is accepted when the mode switching timer 18f started in the interrupt processing 2 counts over. Step SP1
At step SP2, the inverter mode preset in the memory 18c is advanced by one step. At step SP2, the current pattern corresponding to the advanced inverter mode is output, and the process directly returns to the original process.

Therefore, the interruption process 2 causes the inverter mode to be "0", "2", "4", "6", "8", "10".
"0", "2" ... are selected in that order, and the inverter mode is set to "1", "3", "5", "7", "9" by the interrupt processing 3.
“11” “1” “3” ... Since the interrupt processing 2 and the interrupt processing 3 occur alternately, the inverter mode is "0""1""2""3".
"4""5""6""7""8""9""10""1
1 ”,“ 0 ”,“ 1 ”,“ 2 ”,“ 3 ”, ...

FIG. 11 is a diagram schematically showing the configuration of the brushless DC motor drive control device, and FIG. 12 is a diagram showing the internal configuration of the microprocessor 18 of FIG. 11, and FIGS.
The same parts as those of the brushless DC motor drive control device shown in FIG. In this embodiment, as shown in FIG. 11, a switch 21 is connected between the output terminal of the amplifier 15 and the integrator 16, and a capacitor 22 for holding an integral input is connected in parallel with the integrator 16. Has been done. The other components of FIG. 11 are the same as the corresponding components of FIG.

Further, in this embodiment, as shown in FIG. 12, a conduction width control timer 18f 'is adopted instead of the mode switching timer 18f of FIG. 5, and an integral input cut timer 18g is adopted. There is. Then, the energization width control timer 18f ′ is set with a timer value of (energization angle −120) °, and an interrupt process is performed by supplying a countover signal to the mode selection unit 19c ′, the integral input cut timer 18g, and the switch 21. (See interrupt processing 3 in FIG. 12). The integral input cut timer 18g
A timer value is set in advance corresponding to the energization width, and an interrupt process (see interrupt process 4 in FIG. 12) is performed by supplying a countover signal to the switch 21. The interrupt process 3 for the switch 21 is a switch-off process, and the interrupt process 4 is a switch-on process. In addition, the speed control unit 19f 'outputs the voltage command with the current speed and the speed command as inputs. Mode selection unit 19c '
Responds to interrupt processing 2 and interrupt processing 3, and reads out and outputs the corresponding voltage pattern from the memory 18c '. Then, the voltage pattern and the voltage command are supplied to the PWM (pulse width modulation) modulator 18d ', and the PWM modulation signals for three phases are output. This PWM modulation signal is directly supplied to the base drive circuit 20. The other components of FIG. 12 are the same as the corresponding components of FIG.

Table 2 shows voltage patterns corresponding to the inverter mode. However, the voltage pattern is such that each switching transistor 12u1, 12u2, 12v1,
12v2, 12w1, and 12w2 are shown in the ON-OFF states, "1" corresponds to the ON state, and "0" is OF.
Corresponds to F state.

[0043]

[Table 2] FIG. 17 is a waveform diagram of each part of the configuration showing the operation of this embodiment. As shown in (A), (B), and (C) of FIG. 17, the U-phase, V-phase, and W-phase currents IU and I of the brushless DC motor are shown.
V and IW change with the phase shifted by 120 °,
The signal VN output from the amplifier 15 with the rotation of the motor
M changes as shown in (D) of FIG. This signal V
The waveform of the NM is disturbed when entering a mode in which 60 ° is not energized in each phase. Therefore, the switch 21 is turned off so that the disturbance of the waveform is not supplied to the integrator 16.
When set to F, the signal VNO shown in (E) in FIG. 17 is supplied to the integrator 16, the integrated waveform of this signal VNO changes as shown in (F) in FIG. 17, and is affected by the disturbance of the waveform. No integral waveform is obtained.

This integrated waveform is zero cross comparator 1
By being supplied to 7, the position signal which rises or falls at the zero cross point of the integrated waveform is output as shown in (G) in FIG. Interrupt processing 1 is performed by the rising and falling of the position signal, and the phase correction timer 18a is started (see the starting point of the arrow in (H) in FIG. 17). Since the timer value calculation unit 19a sets the timer value in the phase correction timer 18a, the phase correction timer 18a counts over at the time when the timer operation is performed by the set timer value (end point of arrow (H) in FIG. 17). See}. Then, every time the phase correction timer 18a counts over, the interrupt process 2 is performed, and the mode selection unit 19c 'advances the inverter mode by one step. That is, the inverter mode is "0""2""4""6"
"8", "10", "0", "2" ... Are selected in this order.
Further, every time the phase correction timer 18a counts over, the interrupt process 2 is performed, and the energization width control timer 18
f ′ starts (see the starting point of the arrow in (I) in FIG. 17). Then, every time the energization width control timer 18f 'counts over {see the end point of the arrow (I) in FIG. 17}, the interrupt processing 3 is performed, and the mode selection unit 19c' advances the inverter mode by one step. . That is, the inverter mode is "1""3""5""7""9""11"
"1", "3" ... Are selected in this order. Since the interrupt processing 2 and the interrupt processing 3 occur alternately, as shown in (R) of FIG. 17, the inverter mode is "0""1".
"2""3""4""5""6""7""8""9"
“10” “11” “0” “1” “2” “3” ...

Then, by advancing the inverter mode one step by the interrupt processing 2 and the interrupt processing 3, the switching transistor 1 corresponding to each inverter mode.
2u1, 12u2, 12v1, 12v2, 12w1, 1
The ON-OFF state of 2w2 is (L) -in FIG.
It is controlled as shown in (Q). As a result, the brushless DC motor 13 with the energization period set to 150 °
Drive can be achieved.

Further, the interrupt processing 3 causes the integral input cut timer 18g to start (see the starting point of the arrow in (J) in FIG. 17) and the switch control signal for instructing the switch off ((K) in FIG. 17). Reference} to the switch 21. Then, every time the integral input cut timer 18g counts over, the interrupt process 4 is performed, and the switch control signal for instructing the switch on ((K) in FIG. 17).
Is supplied to the switch 21. Therefore, the switch 21 is turned off and the switch 21 is turned off while the waveform of the signal VNM output from the amplifier 15 is disturbed.
Since the value of the signal VNM immediately before is held by the capacitor 22, the disturbance of the waveform of the integrated signal can be eliminated.

FIG. 18 shows the brushless DC of FIGS. 11 and 12.
Integrator output (integrated signal) when the brushless DC motor is driven by using the motor drive control device and when the brushless DC motor is driven by using the brushless DC motor drive control device that does not include the switch 21 and the capacitor 22. FIG. The upper stage corresponds to the latter case, and the lower stage corresponds to the former case. By comparing the upper waveform and the lower waveform, it is possible to eliminate the distortion of the integrated output when this embodiment is adopted,
It can be seen that the magnetic pole position detection signal can be output stably.

FIG. 13 is a flow chart for explaining in detail the processing contents of the interrupt processing 1 of FIG. 12, and an external interrupt request is accepted at each of the rising edge and the falling edge of the magnetic pole position detection signal of the position detector. . Then, in step SP1, the value of the phase correction timer is calculated based on the external phase amount (phase correction angle) command and the position signal cycle signal obtained by the position signal cycle calculation unit 19b, and in step SP2 the phase correction timer 18a. The correction timer value is set to and the phase correction timer is started in step SP3. Then, in step SP4, the cycle measurement timer started in the previous interrupt processing 1 is stopped, and in step SP5 the cycle measurement timer value is read (stored). However, this step SP4, SP
Since the process of 5 is a process for detecting the cycle of the edge of the position signal, after reading the cycle measurement timer value, the cycle measurement timer is immediately reset and started for the next cycle measurement in step SP6. To be done. Then, the stored position signal cycle is calculated in step SP7 (for example, the number of counts per 1 electrical angle is calculated), and the current rotation speed of the brushless DC motor 13 is calculated based on the position signal cycle calculation result in step SP8. In step SP9, the speed is controlled so as to follow the speed command from the outside, the voltage command is output, and the process returns to the original processing.

FIG. 14 is a flowchart for explaining in detail the processing contents of the interrupt processing 2 of FIG. 12, and the interrupt processing 2 is accepted when the phase correction timer 18a started in the interrupt processing 1 counts over. Step S
In P1, the inverter mode preset in the memory 18c ′ is advanced by one step, in step SP2, the voltage pattern corresponding to the advanced inverter mode is output, and in step SP3, the energization width control timer 18f ′ is set by the energization width control timer 18f ′. Timer value {(energization angle-12
0) degree timer value} is calculated, the timer value obtained by the calculation is set in the energization width control timer 18f ′ in step SP4, the energization width control timer 18f ′ is started in step SP5, and the original processing is performed as it is. Return to.

FIG. 15 is a flow chart for explaining in detail the processing contents of the interrupt processing 3 of FIG. 12, and the interrupt processing 3 accepts when the energization width control timer 18f 'started in the interrupt processing 2 counts over. To be In step SP1, a switch-off signal is output to turn off the switch 21, and in step SP2, the integral input cut timer 18g is started.
In step 3, the inverter mode preset in the memory 18c 'is advanced by one step, in step SP4, the voltage pattern corresponding to the advanced inverter mode is output, and the process directly returns to the original process.

Therefore, the inverter mode is set to "0", "2", "4", "6", "8", "10" by the interrupt processing 2.
"0", "2" ... are selected in that order, and the inverter mode is set to "1", "3", "5", "7", "9" by the interrupt processing 3.
“11” “1” “3” ... Since the interrupt processing 2 and the interrupt processing 3 occur alternately, the inverter mode is "0""1""2""3".
"4""5""6""7""8""9""10""1
1 ”,“ 0 ”,“ 1 ”,“ 2 ”,“ 3 ”, ...

FIG. 16 is a flow chart for explaining in detail the processing contents of the interrupt processing 4 of FIG. 12, and the interrupt processing 4 is accepted when the integral input cut timer 18g started in the interrupt processing 3 counts over. . In step SP1, a switch-on signal is output to turn on the switch 21, and the process directly returns to the original process. Figure 1
In the brushless DC motor drive control device of FIG. 1 and FIG. 12, when the switch control signal is sent from the microprocessor 18 to the switch 21, it is necessary to use a photocoupler or the like for insulation. Here, when a low-speed photocoupler or the like is adopted, it is necessary to prevent from entering the non-energizing mode until the switch 21 is actually turned off after the switchoff signal is output from the microprocessor 18. I have to.

FIG. 19 is a block diagram showing the structure of the microprocessor 18 for coping with this request. Figure 1
9 is a point at which the energization width control timer 18f 'is set with a timer value for the turn-on time of the photocoupler by the interrupt processing 3 to start the energization width control timer 18f' and the timer value of the integral input cut timer 18g. 12 is different from the configuration of FIG. 12 in that it is set to a value larger by the turn-on time of the photocoupler, and the configuration of the other parts is the same, so description thereof will be omitted.

FIG. 21 is a waveform diagram of each component showing the operation of this embodiment. (A) to (H) and (L) to (R) are (A) to (H) and (L) of FIG. )-(R). However, FIG. 21 is shown with the time axis (horizontal axis) stretched. As shown by (H) in FIG. 21, the interrupt processing 2 is performed by the phase correction timer 18a counting over, and the energization width control timer 18f 'corresponds to the first timer value {(energization angle -120) °. The timer value} is set, and the energization width control timer 18f 'is started {FIG. 21.
Middle, see the starting point of the arrow to the left of (I)}.

Then, the energization width control timer 18f 'counts over after the first timer value is set, whereby the interrupt processing 3 is performed, and a switch-off signal is output to turn off the switch 21. A second timer value (a timer value for the turn-on time of the photocoupler) is set in the energization width control timer 18f ', and the energization width control timer 1
8f ′ is restarted (see the starting point of the arrow on the right side of (I) in FIG. 21). In addition, this interrupt processing 3 sets a timer value in the integral input cut timer 18g and starts the integral input cut timer 18g.

Also, after the second timer value is set, the energization width control timer 18f 'counts over, and the interrupt process 3 is performed again, and the mode selection unit 19c' advances the inverter mode by one step. , Put one of the phases into the non-energizing mode. Therefore, the inver mode can be advanced by one step in accordance with the timing when the photocoupler turns on and the switch 21 is turned off, and the disturbance of the integrated signal due to the delay of the photocoupler turn-on can be prevented. .

FIG. 20 is a flow chart for explaining the interrupt process 3 of FIG. 19, and the interrupt process 3 is accepted when the energization width control timer 18f 'started in the interrupt process 2 counts over. In step SP1, it is determined whether or not the energization width control timer 18f 'is started in the interrupt process 2. Then, the energization width control timer 18f
If it is determined that ′ has been started in the interrupt processing 2, a switch-off signal is output to turn off the switch 21 in step SP2, the integral input cut timer 18g is started in step SP3, and in step SP4. Second on energization width control timer 18f '
Is set, the energization width control timer 18f 'is started in step SP5, and the process directly returns to the original process. If it is determined in step SP1 that the energization width control timer 18f 'is not started in the interrupt processing 2, the memory 1 is previously stored in step SP6.
The inverter mode set to 8c 'is advanced by one step, and in step SP7, the voltage pattern corresponding to the advanced inverter mode is output, and the process directly returns to the original process.

The interrupt process 1, the interrupt process 2, and the interrupt process 4 are the same as the processes in FIGS. 13, 14, and 16, respectively, and therefore their explanations are omitted. In any of the above embodiments, the disturbance of the signal waveform can be prevented and the magnetic pole position can be accurately detected. Therefore, when there is an imbalance in the motor constant, the brushless DC motor can be stabilized even at the time of a large current. Can be driven to.

Further, instead of setting the current command for each phase in a sine wave shape as shown in (F) to (H) in FIG.
2, the current command for each phase can be set in a triangular wave as shown in (G) to (H).
As shown in (G) to (H), it is possible to set the current command for each phase in a trapezoidal waveform. Further, in any of the above-described embodiments, for example, the current amplitude command or the voltage command is increased or decreased based on a known load pattern (for example, the load pattern of the compressor), and the increased or decreased current amplitude command or the voltage command is used. It is possible to control the torque by supplying it to a multiplier or a PWM modulator.
In this case, since the torque generated by the brushless DC motor is changed according to the load pattern, the brushless D
The speed difference during one rotation of the C motor can be greatly reduced, and the occurrence of vibration can be significantly suppressed.
As a result, even when a one-cylinder compressor in which the load fluctuation during one revolution is remarkable is driven by a brushless DC motor, the speed difference during one revolution can be significantly reduced, and the occurrence of vibration is also greatly suppressed. can do. Therefore, it is possible to use a one-cylinder compressor, which is significantly cheaper than a two-cylinder compressor, and it is possible to significantly reduce the cost of the entire system including the compressor.

[0060]

As described above, according to the invention of claim 1, there is no point where the output waveform of the inverter changes abruptly, and the disturbance of the magnetic pole position detection signal due to the abrupt change of the output waveform is prevented, Brushless D regardless of the imbalance of electric circuit constants
It is possible to drive the C motor stably, and further, it is possible to significantly expand the operating range even in a system in which the load changes abruptly.

The invention of claim 2 has the same effect as that of claim 1. The invention of claim 3 has the same effect as that of claim 1. The invention of claim 4 has the same effect as that of claim 1. According to the invention of claim 5, the speed fluctuation of the brushless DC motor can be eliminated or significantly suppressed, and as a result, the load can be smoothly driven, and any one of claims 1 to 4 Has the same effect.

According to the sixth aspect of the present invention, there is no point where the output waveform of the inverter changes abruptly, the disturbance of the magnetic pole position detection signal due to the abrupt change of the output waveform is prevented, and the electric circuit constant is not changed. The brushless DC motor can be stably driven regardless of the balance, and thus the operation range can be greatly expanded even in a system in which the load changes abruptly.

The invention of claim 7 has the same effect as that of claim 6. The invention of claim 8 has the same effect as that of claim 6. The invention of claim 9 has the same effect as that of claim 6. According to the tenth aspect of the invention, it is possible to reliably prevent the noise caused by the abrupt change of the output waveform of the inverter from being supplied to the rotor position detecting means, and the magnetic pole of the rotor based on the difference voltage. The position can be accurately detected, and as a result, the brushless DC motor can be stably driven regardless of the imbalance of electric circuit constants, and the operating range can be greatly increased even in a system in which the load changes suddenly. It has a unique effect that it can be enlarged.

According to the eleventh aspect of the present invention, the speed fluctuation of the brushless DC motor can be eliminated or greatly suppressed, and as a result, the load can be smoothly driven, and the sixth to tenth aspects. The same effect as any of the above.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of a brushless DC motor drive control device of the present invention.

FIG. 2 is a diagram schematically showing a configuration of a brushless DC motor having a surface magnet structure.

FIG. 3 is a diagram schematically showing a configuration of a brushless DC motor having an embedded magnet structure.

FIG. 4 is a diagram schematically showing a configuration of a brushless DC motor drive control device.

5 is a diagram showing an internal configuration of the microprocessor of FIG.

FIG. 6 is a flowchart illustrating in detail the processing contents of interrupt processing 1 in FIG.

FIG. 7 is a flowchart illustrating in detail the processing contents of interrupt processing 2 in FIG.

FIG. 8 is a flowchart illustrating in detail the processing contents of interrupt processing 3 in FIG.

9 is a diagram showing signal waveforms and processing contents of respective parts of the brushless DC motor drive control device of FIG.

10 is a diagram showing a motor current and an integrator output when a brushless DC motor is driven using the brushless DC motor drive control device of FIG.

FIG. 11 is a diagram schematically showing another configuration of the brushless DC motor drive control device.

12 is a diagram showing an internal configuration of the microprocessor of FIG.

FIG. 13 is a flowchart illustrating in detail the processing contents of interrupt processing 1 in FIG.

FIG. 14 is a flowchart illustrating in detail the processing contents of interrupt processing 2 in FIG.

FIG. 15 is a flowchart illustrating in detail the processing contents of interrupt processing 3 in FIG.

16 is a flowchart for explaining in detail the processing contents of interrupt processing 4 in FIG.

17 is a diagram showing signal waveforms and processing contents of respective parts of the brushless DC motor drive control device of FIG.

18 is a diagram showing an integrator output when the brushless DC motor drive control device of FIG. 11 is used to drive a brushless DC motor, and a brushless DC motor drive control device having no switch 21 and capacitor 22; It is a figure which shows the integrator output at the time of driving a motor.

19 is a diagram showing another internal configuration of the microprocessor of FIG. 11. FIG.

FIG. 20 is a flowchart illustrating in detail the processing contents of interrupt processing 3 in FIG.

FIG. 21 is a diagram of FIG. 1 employing the microprocessor of FIG.
It is a figure which shows the signal waveform of each part of the brushless DC motor drive control device of 1, and the processing content.

22 is a diagram showing signal waveforms and processing contents of respective parts when each phase current command is set in a triangular wave shape in the brushless DC motor drive control device of FIG.

FIG. 23 is a diagram showing signal waveforms and processing contents of respective parts when the phase current commands are set in a trapezoidal wave shape in the brushless DC motor drive control device of FIG. 4.

FIG. 24 is a diagram showing a motor current and an integrated output when the energization width is 120 °.

FIG. 25 is a diagram showing a motor current and an integrated output when the energization width is 150 °.

FIG. 26 is a diagram showing a motor current and an integrated output when the energization width is 180 °.

FIG. 27 is a diagram showing an integral input and an integral output when the energization width is 120 °.

FIG. 28 is a diagram showing an integral input and an integral output when the energization width is 150 °.

FIG. 29 is a diagram showing an integral input and an integral output when the energization width is 180 °.

[Explanation of symbols]

2, 12 Inverter 3, 13 Brushless DC motor 5 Control circuit 13u, 13v, 13w Stator winding 14u, 14v, 14w Resistor 16 Integrator 17 Zero cross comparator 18 Microprocessor 18c 'Memory 19c' Mode selector 21 Switch 22 Capacitor

   ─────────────────────────────────────────────────── ─── Continued front page       (56) Reference JP-A-7-46882 (JP, A)                 JP 62-189993 (JP, A)                 JP-A-7-288992 (JP, A)

Claims (11)

(57) [Claims] 1. A resistor (14u) (14) having one end connected to an output terminal of each phase of an inverter (2) (12).
v) The other ends of (14w) are connected to each other to obtain the first neutral point voltage, and the brushless DC motor (3)
(13) Each phase stator winding (13u) (13v) (1
3w) has one ends connected to each other to obtain a second neutral point voltage, and based on the difference between the first neutral point voltage and the second neutral point voltage, the brushless DC motor (3) (13) Rotor (13
The magnetic pole position of e) is detected, and the output from the inverters (2) (12) controlled based on the detected magnetic pole position is supplied to the brushless DC motors (3) (13) to supply the brushless DC motor (3). Brushless DC driving (13)
A method of driving a motor, wherein an inverter (2) is provided to smoothly change an output waveform of the inverter (2) (12).
A method of driving a brushless DC motor, comprising controlling (12). 2. The brushless DC motor driving method according to claim 1, wherein the inverter (2) (12) is controlled so as to smoothly change the voltage waveform of the inverter (2) (12). 3. The brushless DC motor driving method according to claim 1, wherein the inverter (2) (12) is controlled so as to smoothly change the current waveform of the inverter (2) (12). 4. The brushless DC motor driving method according to claim 1, wherein the inverter (2) (12) is controlled so as to change the output waveform of the inverter (2) (12) into a sine wave shape. . 5. A brushless DC motor (3) during one rotation.
Inverter (2) to suppress the speed fluctuation of (13)
Inverter (2) to change the output waveform of (12)
The brushless DC motor driving method according to claim 1, wherein (12) is controlled. 6. A resistor (14u) (14) having one end connected to the output terminal of each phase of the inverter (2) (12).
v) The other ends of (14w) are connected to each other to obtain the first neutral point voltage, and the brushless DC motor (3)
(13) Each phase stator winding (13u) (13v) (1
3w) has one ends connected to each other to obtain a second neutral point voltage, and based on the difference between the first neutral point voltage and the second neutral point voltage, the brushless DC motor (3) (13) Rotor (13
The magnetic pole position of e) is detected, and the output from the inverters (2) (12) controlled based on the detected magnetic pole position is supplied to the brushless DC motors (3) (13) to supply the brushless DC motor (3). Brushless DC driving (13)
A motor drive device, wherein an inverter (2) is provided to smoothly change the output waveform of the inverter (2) (12).
Inverter control means (5) (18) for controlling (12)
A brushless DC motor driving device comprising: 7. The inverter control means (5) (18) comprises:
The brushless DC motor drive device according to claim 6, wherein the inverter is controlled so as to smoothly change the voltage waveforms of the inverters (2) and (12). 8. The inverter control means (5) (18) comprises:
The brushless DC motor drive device according to claim 6, wherein the inverter (2) (12) is controlled so as to smoothly change the current waveform of the inverter (2) (12). 9. The inverter control means (5) (18) comprises:
The brushless DC motor drive device according to any one of claims 6 to 8, which controls the inverters (2) and (12) so as to change the output waveforms of the inverters (2) and (12) into a sine wave shape. 10. A resistor (14u) (14) having one end connected to the output terminal of each phase of the inverter (2) (12).
v) The other ends of (14w) are connected to each other to obtain the first neutral point voltage, and the brushless DC motor (3)
(13) Each phase stator winding (13u) (13v) (1
3w) has one ends connected to each other to obtain a second neutral point voltage, and based on the difference between the first neutral point voltage and the second neutral point voltage, the brushless DC motor (3) (13) Rotor (13
The magnetic pole position of e) is detected, and the output from the inverters (2) (12) controlled based on the detected magnetic pole position is supplied to the brushless DC motors (3) (13) to supply the brushless DC motor (3). Brushless DC driving (13)
A motor drive device, wherein energization width setting means (18c ') (19c') (18f ') (19a) for setting the energization width of the inverters (2) and (12) to a predetermined width of less than 180 °.
And differential voltage supply interrupting means (21) (22) for interrupting the supply of the differential voltage to the rotor position detecting means (16) (17) corresponding to the non-energizing width of the inverters (2) (12). A brushless DC motor driving device comprising: 11. Inverter control means (5) (18)
However, the inverters (2) and (12) are controlled so as to change the output waveforms of the inverters (2) and (12) so as to suppress the speed fluctuations of the brushless DC motors (3) and (13) during one rotation. The brushless DC motor drive device according to any one of claims 6 to 10.