JP3753074B2 - DC brushless motor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to control of a DC brushless motor driven by an inverter.
[0002]
[Prior art]
FIG. 8 is a diagram showing a configuration of a conventional DC brushless motor device. In FIG. 8, 1 is a DC power source, 2 is a inverter having a plurality of switching elements that operate based on a control signal, and converts a DC voltage Vdc supplied from the DC power source 1 into an AC voltage, and 3 has a plurality of windings. A DC brushless motor composed of a stator 3a and a rotor 3b having a permanent magnet and operated by an AC voltage from the inverter 2 detects a terminal voltage of the DC brushless motor 3, and detects the DC brushless motor rotor 3b. A position detection circuit for detecting a position, 5 is a control circuit for inputting a position signal output from the position detection circuit 4 to generate a control signal for a switch element of the inverter 2, and 6 is a plurality of outputs from the position detection circuit 4. Position calculating means for calculating the magnetic pole position information θm of the rotor 3b of the DC brushless motor based on the position signal, 7 is the magnetic pole position information θm The self-control operation calculating means 10 calculates the voltage command value V1 and the frequency f for self-control operation based on the speed command f *, and the other control operation 10 calculates the voltage command value V0 and the frequency f ′ at the start where position detection is impossible. Calculation means 11 is a selection means for switching the operation method, that is, the other control operation or the self-control operation based on the magnetic pole position information θm, and 12 is each switching element of the inverter 2 based on the DC voltage Vdc and the operation method selected by the selection means 11. Drive control means for generating the control signal.
[0003]
Next, the operation will be described. FIG. 9 is a flowchart showing an example of a conventional DC brushless motor driving procedure (operation of selection procedure 11). First, when driving is started, the selection means 11 selects other control operation (step 1). Next, the other braking operation calculation means 10 starts outputting a time change pattern of a predetermined voltage command value V0 and a frequency f ′. The drive control means 12 obtains a voltage command value and frequency from the other-run operation calculation means 10 via the selection means 11, integrates the frequency to obtain a phase, and calculates a voltage to be output by these, In consideration of the DC voltage Vdc, the PWM duty of each phase is calculated and a PWM signal is output. The inverter 2 drives the switching element based on the PWM signal to rotate the rotor 3b of the DC brushless motor. An example of the pattern of the voltage command value V0 and the frequency f ′ in the other braking operation is shown in FIG. When the frequency is gradually increased with the output voltage constant as shown in FIG. 10, the induced voltage rises due to the increase in the number of rotations of the rotor 3b, and the delay of the rotor rotation phase with respect to the output voltage increases. Possible phase relationship. During other braking operation, the selection means 11 acquires the rotation information of the rotor via the position detection circuit 4 and the position calculation means 6 and can switch to whether or not the induced voltage zero cross is normally detected, that is, to the autonomous driving. (Step 2). If self-control operation is not possible, other control operation is continued, and if self-control operation becomes possible, it switches to self-control operation. FIG. 11 shows a detailed configuration diagram of the autonomous driving calculation means 7. As shown in FIG. 11, the self-driving operation calculating means 7 calculates the voltage command value V1 by integrating the difference (speed deviation) between the speed command and the rotation speed, and outputs it together with the rotation speed information f. Based on the voltage command value V1 and the rotational speed f, the drive control means 12 and the inverter 2 operate to drive the motor. Thereafter, the operation is continued under the self-control operation, and control is performed so that the speed deviation in the self-control operation calculation means 7 becomes zero, that is, speed control is realized. (Step 3)
[0004]
FIG. 12 shows changes over time in the rotational speed and voltage of the motor when the above series of operations is performed. Note that the selection unit 11 selects the other control operation only at the time of startup when the induced voltage becomes unobservable. For this reason, once it switches to self-control operation and shifts to steady operation, it does not return to other control operation again. The position detection means 4 generates a neutral point (connection point of each phase winding) voltage of the motor or a reference voltage (for example, 1/2 of the DC voltage Vdc) corresponding to this voltage, and the voltage waveform of each phase terminal of the motor. And the reference voltage are output to the control means 5 as a position detection signal. This reference voltage is, for example, 1/2 of the voltage Vdc of the DC power supply 1 or the average value of the terminal voltage of the motor. Etc. are used. The magnetic pole position information of the rotor 3b of the DC brushless motor is acquired by the induced voltage of the stator 3a of the DC brushless motor. However, for the terminal voltage, in order for this induced voltage to appear in the terminal voltage of the motor, it is a condition that no current flows through the winding of the corresponding phase. Specifically, it is a condition that the position can be detected when the switching state of the phase inverter is OFF (energization suspension period) and the current continuation state (circulation) immediately after energization is completed. This means that it is necessary to limit the operation state of the inverter 2 in order to perform normal position detection. An example of performing the above-described configuration / operation is disclosed in, for example, Japanese Patent Application Laid-Open No. 11-275887.
[0005]
[Problems to be solved by the invention]
In general, in order to drive a DC brushless motor at a high speed, field-weakening control is effective in which current is applied to a position where the inverter applied voltage phase is advanced from the induced voltage phase of the DC brushless motor. However, as described above, the position detection signal in the sensorless control method using the induced voltage zero cross can be detected only in the energization stop period in which the energization is not performed in each phase. Since the timing is required until the polarity of the position detection signal is changed, the advance angle of the applied voltage phase of the inverter cannot be advanced beyond a predetermined value. When the conventional position detection circuit 4 is used, the position detection signal always detects the zero-cross point of the terminal voltage. Therefore, the ignition voltage can be advanced only to the zero-cross point of the terminal voltage even at the maximum. Therefore, there is a problem that, in realizing high-efficiency operation or high rotation, even if the applied voltage is ignited before the zero cross point of the induced voltage, the demand cannot be met. Further, as disclosed in Japanese Patent Application Laid-Open No. 2000-232762, etc., it is known that in a DC brushless motor, an induced voltage vibration due to an armature magnetomotive force occurs, and a drive abnormality may occur due to this vibration. It is also known that the oscillation of the induced voltage increases as the rotation speed and load increase. In the above document, a countermeasure method by changing the shape of the motor stator is shown as a means to suppress the occurrence of drive abnormality, but there is no effect on drive abnormality in motors other than the stator shape, and it is versatile. There were problems such as scarcity.
[0006]
The present invention has been made to solve the above problems, and an object of the present invention is to provide a DC brushless motor having a wide operating range and high reliability. It is another object of the present invention to provide a DC brushless motor capable of stable operation such as extending the operation range to the high rotation side or eliminating drive abnormality due to induced voltage oscillation.
[0007]
[Means for Solving the Problems]
In the DC brushless motor device according to the first aspect of the present invention, there is a position where the slot opening of the stator, in which the stator winding of the DC brushless motor is concentrated winding, and the pole portion formed by the rotor iron core face each other. An inverter that drives rotation, a current sensor that detects a current flowing into the inverter, a control device that controls the inverter and calculates the position of the rotor of the DC brushless motor without using the rotational position sensor, and performs a self-limiting operation; When it is judged that the current value detected by the current sensor in the self-control operation state at high speed rotation or high load exceeds the predetermined value, the self-control operation is switched to the other control operation, and the phase advanced from the induced voltage phase is energized. The speed control is performed so as to approach the speed command value by the operation to be performed.
[0008]
A DC brushless motor device according to a second aspect of the present invention includes: a voltage determination unit configured to determine whether a voltage command value for driving the DC brushless motor reaches around a maximum voltage at which the number of rotations in the self-controlled operation does not increase; In addition, the operation when the PWM duty of the PWM inverter that drives the DC brushless motor is large is referred to as other control operation.
[0009]
The DC brushless motor device of the present invention according to claim 3 switches from the self-control operation to the other control operation by using both the voltage judgment means and the current judgment means for judging the current detected by the current sensor. .
[0010]
According to a fourth aspect of the present invention, there is provided the DC brushless motor device according to the present invention, wherein the device for detecting the position of the rotor is performed by comparing the terminal voltage of the DC brushless motor with a voltage at a neutral point or a point corresponding to a neutral point. Is.
[0011]
The DC brushless motor device according to the fifth aspect of the present invention has a conduction angle of 120 degrees or more in other braking operation after the output voltage is saturated.
[0012]
According to a sixth aspect of the present invention, the DC brushless motor device according to the present invention controls the operation of the DC brushless motor in a self-limiting operation when a predetermined current or less is detected during the other control operation switched in at least one of the high speed state and the high load state. To switch to.
[0013]
In the DC brushless motor device according to the seventh aspect of the present invention, the predetermined current is not less than the rated current and not more than the overload limit current.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
In the present embodiment, portions that perform the same functions as those of the conventional example are denoted by the same reference numerals and description thereof is omitted. FIG. 1 is a diagram showing a configuration of a DC brushless motor apparatus according to the present invention. In FIG. 1, 1 is a DC power source, 2 is a inverter having a plurality of switch elements that operate based on a control signal, and converts a DC voltage Vdc supplied from the DC power source 1 into an AC voltage, and 3 has a plurality of windings. A DC brushless motor composed of a stator 3a and a motor rotor 3b having a permanent magnet and operated by an AC voltage from the inverter 2 detects a terminal voltage of the DC brushless motor 3, and a rotor 3b of the DC brushless motor. A position detection circuit for detecting the position of the inverter 2, a control circuit 5 for receiving a position signal output from the position detection circuit 4 and generating a control signal for a switch element of the inverter 2, and 6 for an output of the position detection circuit 4. Position calculating means for calculating magnetic pole position information θm of the rotor 3b of the DC brushless motor based on a plurality of position signals; Based on the position information θm and the speed command f *, the voltage command value V1 * for the self-controlled operation and the self-control operation calculating means 10 for calculating the voltage phase θ1 thereof, the DC voltage command value V0 and the voltage phase θ0 are calculated from the speed command f *. Other control operation calculation means for calculating, 11 is a selection means for switching from the other control operation to the self-control operation, and 12 is a control of each switching element of the inverter 2 based on the DC voltage Vdc and the voltage command / voltage phase selected by the selection means 11. Drive control means for creating a signal.
[0020]
FIG. 2 is a flowchart showing the operation of the selection means. Steps 1 and 2 are other control operation processes at the time of start-up. After the start-up, the same operation as in the prior art, that is, position detection becomes possible, and the self-control operation is selected and switched from the other control operation. During the self-limiting operation, the speed control shown in the conventional example is performed, the speed command f * is detected and the magnitude relationship between the detected speed f (step 4) and the voltage command value V1 is the maximum value (Vmax). A determination is made (step 5). Here, when f *> f and V1 = Vmax, that is, when the output voltage reaches the upper limit in the self-controlled operation state and further acceleration is not possible, the operation shifts to the other control operation at high speed. In the other control operation at high speed, the initial value of the frequency f0 is set to the actual speed f, and control is performed so as to gradually approach the speed command value f * (step 6). During the other control operation at high speed, the speed command value f * and the predetermined other control operation lower limit frequency f are set simultaneously with the frequency control. ₂ And a zero cross detection (position detection) of the induced voltage are performed (steps 7 and 8). F ₂ Select a value smaller than the operating frequency that requires the maximum voltage. Where f * <f ₂ When the position can be detected, the selection unit 11 switches from the other control operation to the self-control operation again, and performs speed control similar to the conventional one.
[0021]
An operation example of the above control is shown in FIG. FIG. 5 shows the operation of increasing the speed from step 3 to step 6 in the flowchart of FIG. 2, the operation of decreasing the speed from step 6 to step 3, and the switching from self-control to other control in FIG. 6 means switching from the other system to the self-control in FIG. 5 means switching from step 8 to step 3. In FIG. 5, the horizontal axis represents time and the vertical axis represents voltage and frequency. When a large speed command f * is given during the self-control operation, the voltage increases and accelerates by the self-control operation, and the output voltage becomes maximum. From this time, the other operation is selected, and the output frequency increases while the output voltage remains constant (maximum). Thereby, it turns out that driving | operation is possible at high speed rather than the conventional method. In addition, when the speed command becomes low and the vehicle is decelerated from other control operation, the speed becomes the predetermined frequency f. ₂ Since the operation is switched to the self-controlled operation from the time when the time is lower than, efficient operation is realized without applying an excessive voltage. The reason why the waveform of the speed f following the speed command f * differs between the self-control operation and the other control operation is that the self-control control is a general integral control, and the other control is a constant acceleration control using a ramp function. The ramp function is a function that makes the change in control amount per time constant. Integral control can also be used in other control operations, but field-weakening control is performed to increase speed at high speeds.
[0022]
That is, in order to drive the DC brushless motor to a higher rotation, an operation method in which the inverter applied voltage phase is energized to a phase advanced from the induced voltage phase of the brushless motor, which is called field weakening operation is effective. By advancing the energization phase, the magnetic flux of the armature of the motor stator acts in the direction of weakening the magnetic flux of the magnet, the induced voltage is reduced, and the output voltage is suppressed. In other words, the motor can be operated up to a higher speed under the condition that the output voltage is constant. FIG. 7 shows an explanatory diagram of the relationship between the terminal voltage waveform and the position detection signal when the phase energization is performed in the other control operation. In FIG. 7, the position detection signal should be in the energization suspension period for other control operation, but the position detection is performed even if the phase of the terminal voltage is advanced and the energization start timing is earlier than the timing of position detection as in FIG. Stable operation is possible because of other control that is not related to the signal. Operation that is not limited to the energization stop period becomes possible. The generated torque is sacrificed to increase the speed in the state where the voltage is insufficient due to the field weakening control, and the phase of the rotor 3b is automatically adjusted because the motor generated torque gradually decreases. Late Drive. If this state is viewed on the basis of the rotor phase, the energization phase is advanced, that is, field-weakening operation is automatically achieved. As a result, it is possible to operate at a higher speed than before. On the other hand, since field-weakening control is performed at high speed, it is possible to operate without limiting the stability if the acceleration torque is limited. In order to limit the acceleration torque, the acceleration is kept below a certain level. As described above, by adopting constant acceleration control for the other control operation at high speed, a more stable operation can be obtained.
[0023]
Next, another configuration example of the present invention will be described. This is to eliminate the drive abnormality caused by the distortion of the induced voltage waveform due to the armature magnetomotive force, and the drive abnormality occurs because correct induced voltage zero-cross information cannot be obtained due to the distortion of the induced voltage waveform. The distortion of the waveform depends on the magnitude of the armature current (motor current). In this example, the drive abnormality can be eliminated by using a driving method in which the induced voltage zero cross is not detected when the current is detected and becomes equal to or greater than a predetermined value, that is, other control operation. FIG. 3 is a configuration diagram of this example. In FIG. 3, reference numeral 13 denotes a current sensor for detecting a current flowing into the inverter 2 (hereinafter referred to as an input current). Other configurations are the same as those in FIG. The current value detected by the current sensor 13 is input to the selection means 11, and based on this, other braking operation and self-limiting driving are determined.
[0024]
FIG. 4 is a flowchart showing the operation for the configuration of FIG. Step 1-3 is the same as FIG. During the self-restricting operation in step 3, the speed is controlled and the input current I is monitored, and a predetermined value I ₁ (Step 4a). Here, the input current I is a predetermined value I ₁ If it is determined that the value exceeds, switch to other control. During high speed other control at Step 6, the control is performed so that the speed approaches the speed command based on the fixed voltage, and the input current is monitored. Here, as shown at Step 7a, the input current I is a predetermined value I. ₂ If the position is normally detected as in step 8, the operation is shifted to the self-control operation.
[0025]
I ₁ , I ₂ Is in the range of current values at which drive abnormality due to armature current does not occur. ₁ > I ₂ Set under the following conditions. In this example, a current to be detected is input. However, the present invention is not limited to this, and a motor current may be detected. Since the occurrence of drive abnormality depends on the motor current, the current to be measured may be an amount related to the motor current, such as an AC power supply current or power, or a physical quantity proportional to the current or power. Of course. The measurement value can be an instantaneous value, an average value, or an execution value regardless of where the measurement is made. In the above example, the inverter input current is described as an example. By measuring with this inverter input current, the reference voltage which is the ground of the detection circuit and the control circuit can be shared, and the structure can be simplified and standardized. Further, since the drive abnormality is likely to occur during high-speed operation in which the interval of the induced voltage zero cross is shortened, the voltage for determining the voltage in Step 5 of FIG. 2 is combined with the operation of the flowchart of FIG. By controlling using both the determination means and the current determination means for determining the current in step 4a in FIG. 4, a wide driving range and a stable drive device can be realized. The combination of operation flows may be selected in consideration of the type and application of the load driven by the DC brushless motor device, such as speed and current, the operating range, and the like.
[0026]
Next, a motor shape that is used in the DC brushless motor device of the present invention and that is more effective will be described. FIG. 6 is a block diagram of a concentrated winding motor. In FIG. 6, 20 is a stator core, 20a is a stator tooth portion, 20b is a slot opening, 21 is a rotor magnet, 22 is a rotor core, 22a is a rotor pole portion, and 23 is a stator winding. Here, when the stator winding 23 is energized, the magnetic flux generated thereby flows in a magnetic circuit formed by the rotor pole portion 22 a, the rotor core 22, and the stator core 23. Here, when the position of the rotor pole portion 22a is at a position facing the rotor tooth portion 20a, the magnetic circuit is small, but the position of the rotor pole portion 22a is at a position facing the slot opening 20b. In some cases, the gap is large and the magnetoresistance is large. That is, when the inter-pole portion passes through the slot opening, an abrupt change in magnetic flux occurs, and an electromotive force is generated in the stator winding 23. This electromotive force is a cause of malfunction of the position detection circuit of the inverter. In the concentrated winding motor, since the magnetic flux flowing per stator tooth portion 20a is large, the influence of the electromotive force is large, which may be a big problem in control. Since the control shown in the present embodiment switches between the self-controlled operation and the other-controlled operation according to the current, the concentrated winding motor can be more stably operated particularly in a high load state where the current value is large.
[0027]
In order to achieve an increase in the operating range on the high speed side and the elimination of motor drive abnormalities, the present invention is based on a speed command alone from a self-controlled operation (speed feedback operation) based on position detection information when the rotational speed is high. This is a method of controlling to switch to braking operation (speed open loop operation). This is because, in an inverter that performs PWM driving of a DC brushless motor with sensorless 120-degree energization, when the PWM duty is maximum or exceeds a certain value, the operating frequency is controlled only by the speed command value without using the speed obtained by position detection. This is an open loop control. Corner It can be 120 degrees or more.
[0028]
In other words, in order to achieve the expansion of the driving range on the high speed side and the elimination of motor drive abnormalities, when the current is large, from the speed feedback operation (self-regulated operation) based on the position detection information to the open loop operation based only on the speed command ( It is a method of controlling to switch to other control operation).
[0029]
Also, based on speed command only from speed feedback operation (self-regulated operation) based on position detection information when PWM duty of PWM inverter is large, in order to achieve high speed side driving range expansion and elimination of motor drive abnormality It is a method of controlling to switch to open loop operation (other system operation).
[0030]
Furthermore, in order to realize high-efficiency operation, concentrated winding is adopted as the stator structure of the motor of the DC brushless motor device.
[0031]
Further, in order to realize the circuit with an inexpensive circuit, a method of comparing the terminal voltage of the DC brushless motor with the voltage at the neutral point or a point corresponding to the neutral point is adopted as a method for detecting the position of the motor.
[0032]
As described above, according to the present invention, the circuit can be realized at low cost because it is driven while suppressing the peak of the output current based on the zero-cross saturation level calculation means for the field-weakening induced voltage during high-speed rotation.
[0033]
In addition, since integral control is used in self-regulated operation and switched to constant acceleration control at high speed, the integrator in the control circuit does not diverge and can be operated stably.
[0034]
Further, the present invention can stably operate even when the number of rotations is changed, can stably operate with high efficiency and a wide frequency range, and can have an inexpensive circuit configuration. In the above description, it has been explained that the lower limit frequency in other control operation at high speed or high load, that is, the speed is higher than the rated frequency and lower than the maximum frequency. This is because it is desirable. Since the speed limit performance rather than efficiency, that is, stable operation up to a higher speed is required at higher speeds than the rated value, the concept of other control operation is explained. This is the same in the operation under a high load state. In the rated load state, the self-restricting operation may be performed by pursuing the efficiency, and the other operation that is stable in the higher load state may be used.
[0035]
However, the switching conditions may be set according to the load and purpose of using the DC brushless motor device, and it is not necessary to set the conditions for switching to other braking operation at high speed or high load. It is natural that the switching position should be set according to the classification of the area where the engine is required and the area where stable operation is required at a higher speed or higher load, or according to where the high speed is desired. is there. In particular, the DC brushless motor device of the present invention is preferably used for a load that does not require much torque at high speeds for the purpose of performing field-weakening operation that increases the rotational speed at the sacrifice of torque during high speed other speed operation. For example, in the case of a compressor used in a refrigeration cycle, the control of the present invention works particularly effectively because of characteristics close to a constant torque load in a high speed range. Further, when the target load is an air conditioner, the range of the other control operation may be switched from the self-control operation to the other control operation when performing the heating operation under a low outside air temperature condition. The low outside air heating is operated at a high rotational speed because the load torque is small. If the other control operation is performed in this state, the rotation speed can be further increased, and the heating capacity can be further increased, so that an air conditioner having a small structure and a large heating capacity can be realized. In this case, if the outside air temperature is lower than, for example, 10 degrees after the air conditioner is instructed to perform the heating mode operation, it is determined that the speed is high or the load is high, and the self-control operation is switched to the other control operation.
[0036]
【The invention's effect】
In the DC brushless motor device according to the first aspect of the present invention, there is a position where the slot opening of the stator, in which the stator winding of the DC brushless motor is concentrated winding, and the pole portion formed by the rotor iron core face each other. An inverter that drives rotation, a current sensor that detects a current flowing into the inverter, a control device that controls the inverter and calculates the position of the rotor of the DC brushless motor without using the rotational position sensor, and performs a self-limiting operation; When it is determined that the current value detected by the current sensor has exceeded a predetermined value in the self-limiting operation state during high-speed rotation or high load, switching from the self-control operation to the other control operation, the phase is advanced from the induced voltage phase. Since the speed control is performed so as to approach the speed command value by the energized operation, an efficient and highly reliable device can be obtained.
[0037]
A DC brushless motor device according to a second aspect of the present invention includes: a voltage determination unit configured to determine whether a voltage command value for driving the DC brushless motor reaches around a maximum voltage at which the number of rotations in the self-controlled operation does not increase; In addition, since the operation when the PWM duty of the PWM inverter for driving the DC brushless motor is large is the other control operation, a device capable of stable operation at high speed rotation can be obtained.
[0038]
The DC brushless motor device according to the third aspect of the present invention controls both the voltage judgment means and the current judgment means for judging the current detected by the current sensor to switch from the self-control operation to the other control operation. A device capable of driving and stable driving is obtained.
[0039]
The apparatus for detecting the position of the rotor of the DC brushless motor device of the present invention according to claim 4 is performed by comparing the terminal voltage of the DC brushless motor with the voltage at the neutral point or a point corresponding to the neutral point. Therefore, a simple and inexpensive device can be obtained.
[0040]
Since the DC brushless motor device according to the fifth aspect of the present invention has an energization angle of 120 degrees or more in the other control operation after the output voltage is saturated, a device capable of expanding the operating range on the high speed side is obtained.
[0041]
According to a sixth aspect of the present invention, the DC brushless motor device according to the present invention controls the operation of the DC brushless motor in a self-limiting operation when a predetermined current or less is detected during other braking operation switched in at least one of a high speed state and a high load state. Therefore, efficient operation is possible.
[0042]
In the DC brushless motor device according to the seventh aspect of the present invention, since the predetermined current is not less than the rated current and not more than the overload limit current, it can be operated with high stability in a high load state.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a DC brushless motor device according to a first embodiment of the present invention.
FIG. 2 is a flowchart showing an operation according to the first embodiment of the present invention.
FIG. 3 is a configuration diagram of another DC brushless motor device according to Embodiment 1 of the present invention.
FIG. 4 is a flowchart showing another operation in the first embodiment of the present invention.
FIG. 5 is an explanatory diagram showing an operation example of control according to the first embodiment of the present invention.
FIG. 6 is a configuration diagram of a concentrated winding motor of the DC brushless motor device according to Embodiment 1 of the present invention.
FIG. 7 is a terminal voltage waveform diagram of the DC brushless motor device according to Embodiment 1 of the present invention.
FIG. 8 is a configuration diagram of a conventional DC brushless motor device.
FIG. 9 is a flowchart showing a driving procedure of a conventional apparatus.
FIG. 10 is a diagram showing a pattern of voltage command and frequency in a conventional other control operation.
FIG. 11 is a diagram showing a relationship between a speed command and a voltage saturation level of a conventional device.
FIG. 12 is a diagram showing a change over time in speed and voltage of a conventional device.
[Explanation of symbols]
1 DC power supply, 2 inverter, 3 DC brushless motor, 3a stator of DC brushless motor, 3b rotor of DC brushless motor, 4 position detection circuit, 5 control means, 6 position calculation means, 7 self-control operation calculation means, 10 others Braking operation calculation means, 11 selection means, 12 drive control means, 20 stator core, 21 rotor magnet, 22 rotor core, 23 stator winding.

Claims (7)

An inverter that drives rotation in which a stator slot opening of a DC brushless motor has a concentrated winding and a position where an interpole formed by a rotor iron core is opposed to each other, and an electric current flowing into the inverter A current sensor to detect, and a control device that controls the inverter and calculates the position of the rotor of the DC brushless motor without using a rotational position sensor, and performs a self-limiting operation, at the time of high speed rotation or high load When it is determined that the current value detected by the current sensor exceeds the predetermined value in the self-limiting operation state, the self-control operation is switched to the other control operation, and the speed command value is approached by the operation that energizes the phase advanced from the induced voltage phase. DC brushless motor device characterized by performing speed control as described above. Voltage determination means for determining whether or not a voltage command value for driving the DC brushless motor reaches a vicinity of a maximum voltage at which the rotation speed does not increase in the self-controlled operation state, and PWM of a PWM inverter that drives the DC brushless motor 2. The DC brushless motor device according to claim 1 , wherein the operation when the duty is large is the other control operation . 3. The DC brushless motor according to claim 2, wherein both the voltage judgment means and the current judgment means for judging the current detected by the current sensor are used to switch from the self-limiting operation to the other braking operation. apparatus. Apparatus for detecting the position of the rotor, one of claims 1 to 3, characterized in that by comparing the voltage of the point corresponding to the terminal voltage of the DC brushless motor to the neutral point or neutral point DC brushless motor device according to claim 1. In another system operation after the output voltage is saturated, DC brushless motor according to any one of claims 1 to 4, characterized in that a conduction angle of 120 degrees or more. Other system during operation, which is switched at least one of a high speed state and the high-load state upon detection of less than a predetermined current, DC of claim 1, wherein the switching to self-control operation the operation of the DC brushless motor Brushless motor device. The DC brushless motor device according to claim 6, wherein the predetermined current is not less than a rated current and not more than an overload limit current.

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