JP3815584B2 - Sensorless synchronous motor drive device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sensorless synchronous motor driving device.
[0002]
[Prior art]
FIG. 6 shows a configuration of a conventional motor control circuit described in Japanese Patent Laid-Open No. 6-284382.
This conventional example is intended to provide a DC motor control device that can operate stably and optimally in response to changes in operating conditions such as rotational constants, motor winding specifications, DC voltage, and motor current. The configuration is composed of a motor current detecting means, a motor induced voltage detecting means, and a microcomputer. The actual commutation timing is a phase processed in the microcomputer so that the motor current is minimized. The DC motor control circuit is such that the correction amount is added to the commutation position information obtained by the motor-induced voltage detection means and determined, and the commutation timing is determined while always searching for the minimum value of the motor current. It is said that it can realize the optimal driving state without fully worrying about abnormal phenomena such as step-out while fully demonstrating the efficiency of the motor itself.
[0003]
That is, in FIG. 6, the AC voltage input from the commercial power source 601 is converted to DC by a voltage doubler rectifier circuit including a diode 602 and a capacitor 603. By the three-phase bridge type inverter configured, switching (commutation switching) is performed as appropriate, and an AC current is supplied to the DC motor 606 for the compressor. The commutation switching is performed by inputting the motor terminal voltage taken from the motor terminals Vu, Vv, and Vw to a microcomputer (hereinafter referred to as a microcomputer) via a motor induced voltage detection circuit and performing an appropriate phase correction process in the microcomputer. Output to the driver as a commutation signal. In the correction process, a DC current (a motor current and a crest value coincide with each other) detected by the current detection resistor 607 is taken into the current detection circuit and then input to the microcomputer to use this current information.
[0004]
On the other hand, the rotational speed command signal given from the outside is supplied to the microcomputer via the interface, but depending on the difference between the actual rotational speed obtained from the measurement of the cycle of the command rotational speed and the motor induced voltage one detection signal, The chopper duty is calculated in the microcomputer and output to the modulation circuit as a chopper signal.
The transistor 604 is switched at an appropriate commutation timing while being turned on / off by a chopper having a duty corresponding to the difference between the actual rotational speed and the command rotational speed.
[0005]
[Problems to be solved by the invention]
However, in the conventional configuration, since the commutation timing of the motor is detected by detecting the induced voltage from the terminal voltages of the motor terminals Vu, Vv, and Vw of the driving device, both the upper and lower transistors do not switch in each phase. A section (see FIG. 7) is required.
For this reason, there is a problem that the output voltage to the motor becomes small and the motor maximum output torque at a high speed is small. In addition, since the adjustment range of commutation timing is limited to the pause interval range, there is a problem that the corresponding range of output torque is narrow and weak against load fluctuations.
Therefore, the present invention solves the above-mentioned problems of the conventional example, and can increase the motor output torque even at high speed and load fluctuation compared to a sensorless synchronous motor that does not have a rotor position detecting means directly connected to the motor. Therefore, it is an object of the present invention to provide a sensorless synchronous motor driving device capable of maintaining synchronous operation as it is without stepping out the motor.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a sensorless synchronous motor driving apparatus in which the phase difference between the output voltage and the motor induced voltage is increased with reference to the output voltage of the driving apparatus to the sensorless synchronous motor. Comprises frequency changing means for decreasing the output frequency of the output voltage and increasing the output frequency of the output voltage when the phase difference decreases.
[0007]
Thus, according to the present invention, the output voltage frequency corresponding to the rotational speed fluctuation of the motor can be realized with a short response speed corresponding to the control sampling time of the arithmetic unit , and the synchronous operation is performed for the load fluctuation within the normal output torque range. There is a special effect that can be sustained.
[0008]
The present invention also Oite the drive of the sensorless synchronous motor, it is determined whether within a phase difference range that is set beforehand by the calculating means values detected by the phase difference detecting means, the detected value is the position When the difference is within the phase difference range, the output voltage frequency to the synchronous motor is limited to a preset frequency range centered on the frequency corresponding to the command rotational speed of the synchronous motor by the calculating means, and the detected value is when in the outside phase difference range, by the calculating means the output voltage frequency of the synchronous motor, and controlling only change frequency component proportional to the phase difference in excess.
[0009]
Thus, according to the present invention, the output voltage frequency corresponding to the rotational speed fluctuation of the synchronous motor can be realized with a short response speed corresponding to the control sampling time of the arithmetic unit, and the synchronous motor speed is prevented from greatly deviating from the command rotational speed. Thus, there is a remarkable effect that stable speed control can be realized.
[0010]
Further, the present invention integrates a difference value obtained by subtracting a detection value detected by the phase difference detection means from a phase difference value set in advance by the arithmetic device, and outputs the output voltage frequency to the synchronous motor by the arithmetic device . The control is changed by a frequency proportional to the integral value.
[0011]
In this way, the present invention is proportional to the phase difference exceeding when the sensorless synchronous motor enters the step-out transition state beyond the phase range preset by the arithmetic unit due to sudden load fluctuation or overload. Since the control is changed by an amount corresponding to the frequency, it is possible to immediately return to a stable state without generating vibration in a normal phase.
Further, when the phase difference increases during high-speed overload, the difference value obtained by subtracting the detection value detected by the phase difference detection means from the phase difference value set in advance by the arithmetic unit is integrated to the synchronous motor. By changing control of the output voltage frequency by a frequency proportional to this integral value, the synchronous motor speed can be automatically and slowly reduced to the maximum speed that can handle overload , and when the load becomes lighter Is capable of realizing a synchronous operation that automatically returns to the command speed and contributes to improving the versatility of this type of device, and is highly convenient in that fine adjustment of the load speed in this field can be made smoothly. .
[0012]
Furthermore, the present invention energizes the output terminal voltage to the synchronous motor as a rectangular wave voltage, and synchronizes with the fundamental wave component obtained by removing the harmonic component due to the rectangular wave voltage energization from the output voltage to the synchronous motor. and controlling change the output voltage frequency of the sensorless synchronous motor based on the phase difference value of the induced voltage from the motor.
[0013]
Also a synchronous motor terminal voltage output to sensorless synchronous motor as energization of the rectangular wave voltage rather than a sine wave voltage, can achieve the above effects, a great place to contribute to the ease of simplicity and maintenance control.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
The circuit configuration of Embodiment 1 of the present invention is shown in the block diagram of FIG. In all surfaces, the same reference numerals represent the same or corresponding members.
In FIG. 1, 1 is a DC power supply voltage smoothing capacitor, 2 is an IGBT transistor, 3 is a microcomputer, 4 is a drive circuit that transmits an on / off command from the microcomputer 3 to the IGBT transistor 2 to the IGBT ranger 2 as a drive signal. , 5 and 6 are current detectors for detecting the motor current, 7 is a DC power supply voltage detector, 8 is a rectifier diode, 9 is a commercial power supply, 10, 11 and 12 are three-phase Y on the sensorless synchronous motor stator side U, V, and W phase armature coils connected to the connection, 13 is a rotor of a sensorless synchronous motor having a plurality of magnets, and 14, 15, and 16 are U, V, and W phase output terminals, respectively.
The microcomputer 3 can control the output voltage and output frequency to each phase of the motor by controlling the on / off ratio to the IGBT transistor 2 via the drive circuit unit 4 based on the detection value by the DC power supply voltage detector 7. Also, the output frequency and the instantaneous output voltage value for each phase of the motor can be grasped.
[0015]
Furthermore, the instantaneous current value of each phase of the motor can also be detected based on the detection values of the current detectors 5 and 6. Based on the simultaneous instantaneous voltage value and instantaneous current value of each phase, the output frequency, and each characteristic value of the sensorless synchronous motor set in the microcomputer 3 in advance, the microcomputer 3 calculates the phase output voltage to the synchronous motor by calculation. Detects the phase difference from the phase induced voltage from the synchronous motor [Fig. 4: Diagram showing the phase difference between the phase output voltage to the synchronous motor and the phase induced voltage from the synchronous motor, see] It is omitted because it is a known technique. This is performed every short sampling time (for example, Ts = 5 mS).
[0016]
The phase difference detection value Φ ₀ in the previous sampling and the current phase difference detection value Φ ₁ are calculated by the following method, and the difference between the output frequency and the frequency corresponding to the synchronous motor rotation speed is detected.
Δf ₁ = K · (Φ ₀ −Φ ₁ ) / (2π · Ts) (Equation 1)
However, K is a proportionality constant and is set to 1 here.
In addition, for each phase value used in the calculation, a digital filter may be inserted to take into account earlier detection values.
Only the frequency corresponding to Δf _{1 is} added and the output frequency is changed by the control sampling after the calculation.
Thus, the output frequency F ₀ to the synchronous motor corresponding to the rotational speed fluctuation of the synchronous motor is output.
[0017]
Further, the microcomputer 3 compares the phase value detected by the above method with a phase value set in advance (for example, θ ₁ = π · 85/180), and the detected phase value Φ ₁ is small and the output frequency F _{When 0} exceeds the preset frequency limit range centered on the frequency corresponding to the synchronous motor command speed, this limit value is set as the output frequency.
Then, the phase value detected by the above method is compared with the phase value θ set in advance by the microcomputer 3, and when the detected phase value Φ ₁ is large, in addition to the detected value Δf ₁ of the frequency difference, By calculation, only the frequency corresponding to the calculated value Δf _{2 is} added, and the output frequency is changed by control sampling after the calculation.
Δf ₂ = (θ−Φ ₁ ) · K ₁ …………………… (Formula 2)
However, K ₁ is a proportionality constant.
[0018]
Furthermore, the difference value obtained by subtracting the phase value Φ ₁ detected by the above method from the phase value (for example, θ ₁ = π · 85/180) set in advance by the microcomputer 3 is integrated, and this integrated value is obtained by the following calculation. A frequency component proportional to Δf _{3 is} added, and the output voltage frequency to the synchronous motor is added to Δf ₁ and Δf ₂ , and further changed by control sampling after calculation.
When the integral value becomes a positive value (a negative value at the time of control output torque), the integral value is reset to zero.
Δf ₃ = {Σ (θ ₁ −Φ ₁ )} · K ₂ (Equation 3)
However, K ₂ is a proportionality constant.
[0019]
(Embodiment 2)
Next, a second embodiment (the configuration is the same as that in FIG. 1) of the present invention will be described with reference to FIG.
FIG. 2 shows an on / off command output from the microcomputer 3 to the IGBT transistor 2 in order to make the output voltage to the synchronous motor terminal into a rectangular wave voltage waveform. Here, the output voltage to each phase synchronous motor terminal is energized with a rectangular wave voltage of 180 degrees.
[0020]
FIG. 3 shows the relationship between the line output voltage waveform and the phase output voltage waveform to the synchronous motor at this time.
As can be seen from FIG. 3, the phase output voltage phase coincides with the phase θ of the rectangular wave voltage fundamental wave component of the synchronous motor terminal. Here, the microcomputer 3 controls the on / off ratio to the IGBT transistor 2 via the drive circuit 4 based on the detection value by the DC power supply voltage detector 7, so that a rectangular wave to each phase terminal of the synchronous motor is obtained. The voltage output amplitude value and the output voltage frequency can be controlled, and the output voltage frequency, the phase output voltage phase value θ, and the rectangular wave voltage amplitude Ep to each phase terminal of the synchronous motor can be grasped.
[0021]
Here, the microcomputer 3 corrects the phase output voltage instantaneous value (for example, Eu of the U phase) to each phase of the synchronous motor based on the following.
Eu = (Ep) x (K ₃ ) x (Sinθ)
However, K ₃ is a proportionality constant determined by the rectangular wave voltage energization section width.
Based on this, the instantaneous current value of each phase of the synchronous motor detected from the current detectors 5 and 6, the output voltage frequency, and each characteristic value of the sensorless synchronous motor set in the microcomputer 3 in advance, the synchronous motor is calculated. The phase difference between the phase output voltage to and the phase induced voltage from the synchronous motor is detected. The subsequent processing is the same as in the first embodiment.
[0022]
【The invention's effect】
As described above, according to the present invention, the synchronous motor output torque can be increased even at a high speed, and the synchronous motor is stepped out even with respect to load fluctuations, compared with a sensorless synchronous motor that does not have a rotor position detecting means directly connected to the synchronous motor. There is a particularly excellent effect that the synchronous operation can be continued as it is.
[0023]
That is, in this way, according to the present invention, the output voltage frequency corresponding to the rotational speed fluctuation of the motor can be realized with a short response speed corresponding to the control sampling time of the arithmetic unit, and with respect to the load fluctuation within the normal output torque range. Has a special effect that the synchronous operation can be continued.
[0024]
Further, according to the present invention, the output voltage frequency corresponding to the rotational speed fluctuation of the synchronous motor can be realized with a short response speed corresponding to the control sampling time of the arithmetic unit, and the synchronous motor speed is prevented from greatly deviating from the command rotational speed. Thus, there is a remarkable effect that stable speed control can be realized.
[0025]
Further, the present invention provides a frequency component proportional to the phase difference exceeding when the sensorless synchronous motor enters a step-out transition state beyond the phase range preset by the arithmetic unit due to sudden load fluctuation or overload. Since only the control is changed, it is possible to immediately return to a stable state without generating vibration in a normal phase.
[0026]
In addition, when the phase difference increases during high-speed overload, the difference value obtained by subtracting the detection value detected by the phase difference detection means from the phase difference value set in advance by the arithmetic unit is integrated to the synchronous motor. The output voltage frequency is controlled by a frequency proportional to the integral value, and when the integral value is positive (negative value at braking output torque), the integral value is reset to zero to overload. Synchronous motor speed can be automatically and slowly reduced to the maximum speed that can handle this, and synchronous operation that automatically returns to the command speed when the load becomes lighter can be realized. Contributing to the improvement in performance, it is very convenient that fine adjustment of the load speed in this field can be made smoothly.
[0027]
Even if the synchronous motor terminal output voltage to the sensorless synchronous motor is a rectangular wave voltage instead of a sine wave voltage, the above effect can be realized as it is, contributing to the simplicity of control and the ease of maintenance. It is enormous and has a profound effect on the development of technology related to this, and the expansion of its scope of application is considered immense and enormous.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a circuit configuration of a step-out prevention device in a sensorless synchronous motor driving device according to a first embodiment of the present invention. FIG. 2 shows a synchronous motor terminal voltage in a rectangular wave according to a second embodiment of the present invention. FIG. 3 is a diagram showing an on / off command output signal from the microcomputer to the IGBT transistor when the voltage waveform is 180 degrees energized. FIG. 3 shows the synchronous motor terminal voltage as a rectangular wave voltage waveform 180 degrees in the second embodiment of the present invention. Fig. 4 shows the relationship between the synchronous motor terminal voltage waveform, the line output voltage waveform to the synchronous motor, and the phase output voltage waveform when energized. [Fig. 4] Phase output voltage to the synchronous motor and from the synchronous motor Fig. 5 shows the phase difference from the phase induced voltage. Fig. 5 shows the relationship between the phase difference between the phase output voltage to the synchronous motor and the phase induced voltage from the synchronous motor, and the synchronous motor output torque.
(a) is a characteristic diagram when the rotor of a sensorless synchronous motor is a non-salient pole type
FIG. 6B is a characteristic diagram when the rotor of the sensorless synchronous motor is a salient pole. FIG. 6 is a block diagram showing a circuit configuration of a conventional brushless DC motor driving apparatus. The figure which showed the rest period of the semiconductor switching element for detecting a motor induced voltage in the example of composition of a drive device.
1 DC power supply voltage smoothing capacitor 2 IGBT transistor 3 Arithmetic unit [microcomputer]
4 Drive circuit sections 5, 6 Current detector 7 DC power supply voltage detector 8 Rectifier diode 9 Commercial power supplies 10, 11, 12 Armature coil 13 Rotors 14, 15, 16 Output terminal section

Claims (5)

In the sensorless synchronous motor drive device,
When the phase difference between the output voltage and the motor induced voltage is increased with reference to the output voltage to the sensorless synchronous motor by the driving device, the output frequency of the output voltage is decreased, and the phase difference is decreased. Comprises a frequency changing means for increasing the output frequency of the output voltage.   2. The sensorless synchronous motor drive device according to claim 1, wherein the frequency changing means has a function of limiting the output frequency within a predetermined range centered on the output frequency corresponding to the motor command speed. Means for detecting the phase difference;
The frequency changing means has a function of further reducing the frequency calculated and calculated based on the excess when the detected value of the phase difference exceeds a predetermined value set in advance. 2. A sensorless synchronous motor drive device according to 1. Means for detecting the phase difference;
Means for integrating a difference value obtained by subtracting the detected value of the phase difference from a predetermined value set in advance;
2. The sensorless synchronous motor driving apparatus according to claim 1, wherein the frequency changing means has a function of further adding a frequency proportional to the integral value.   The phase difference is a phase difference between the fundamental wave component and the motor induced voltage with reference to a fundamental wave component of a rectangular wave output voltage to the sensorless synchronous motor by the driving device. Item 5. The sensorless synchronous motor drive device according to any one of Items 4 to 4.

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