JP3590541B2 - DC brushless motor drive - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sensorless DC brushless motor driving device, and more particularly to a step-out detecting device for driving a DC brushless motor without using a position signal.
[0002]
[Prior art]
FIG. 15 is a configuration diagram showing a conventional DC brushless motor driving device disclosed in Japanese Patent Application Laid-Open No. 7-87782, for example. In the figure, 1 is an inverter circuit, 2 is a DC brushless motor, 25 is a position detection circuit for detecting the position of the rotor of the DC brushless motor 2, 26 is a drive signal for each transistor of a switching circuit 34 having a plurality of switching elements. Is an abnormality detection circuit that sends an abnormality detection command to the control unit 26, 28 is a reverse current detection circuit that detects a current flowing in the shunt resistor 31 in a direction opposite to the normal direction, and 29 is a shunt resistor 31 A forward current detection circuit for detecting a normal forward current flowing, a current detection circuit 30 having a forward current detection circuit 29 and a reverse current detection circuit 28, a diode bridge 32 for rectification, and a diode 33 This is a rectifier circuit having a bridge 32 and a smoothing capacitor.
[0003]
Next, the operation will be described.
When the DC brushless motor 2 is driven, a switching circuit 34 having a plurality of switching elements and a rectifying circuit 33 for applying a DC voltage to the switching circuit 34 are provided. The rectifying circuit 33 and the switching circuit 34 use an inverter. The circuit 1 is configured. Then, the position of the rotor of the DC brushless motor 2 is sequentially detected by the position detection circuit 25, and each switching element of the switching circuit 34 is turned on and off in accordance with the detected position, so that power is supplied to each phase of the DC brushless motor 2. Are sequentially switched, and the DC brushless motor 2 is driven.
[0004]
In the inverter circuit 1, a shunt resistor 31 for current detection is connected to a connection line between the rectifier circuit 33 and the switching circuit 34, and a current detection circuit 30 is connected to both ends of the shunt resistor 31.
The current detection circuit 30 detects a normal forward current flowing through the shunt resistor 31 by the forward current detection circuit 29, and detects a reverse current flowing through the shunt resistor 31 by the reverse current detection circuit 28 in a direction opposite to the normal direction. The directional current is detected, and the switching circuit 34 can be protected even at the time of step-out or when a reverse current is flowing (during regenerative operation: sudden deceleration, etc.).
[0005]
[Problems to be solved by the invention]
The above-described step-out detection method in the conventional DC brushless motor driving device is effective when a back electromotive voltage is detected and used as a position signal or when a Hall IC or the like is used as a position signal. When a DC brushless motor is driven without using a motor, the difference between the current value during step-out and the current value during normal operation is small, so that step-out cannot be detected. Due to the relationship, there is an inconvenience when it is necessary to detect out-of-step at high speed.
[0006]
SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and a driving apparatus for a DC brushless motor having a stable and high-speed step-out detection method even when a DC brushless motor is driven without using a position signal. The purpose is to provide.
[0007]
[Means for Solving the Problems]
A DC brushless motor driving device according to the present invention includes a switching circuit having a plurality of switching elements, and a DC voltage applying unit that applies a DC voltage to the switching circuit, converts a DC voltage into an AC voltage, and fixes the DC voltage. Voltage-type inverter that supplies a voltage to a DC brushless motor composed of a stator having a child winding and a rotor having a permanent magnet, a zero crossing of a terminal voltage of the DC brushless motor, and a zero crossing of a current flowing in the DC brushless motor. A voltage-type inverter control device that detects a phase difference and controls the terminal voltage of the DC brushless motor so that the phase difference approaches a predetermined target phase difference; and in this control device, the phase difference matches a target value. If the terminal voltage is higher than the specified upper limit or lower than the specified lower limit, operation is stopped It is obtained by a shutdown means that.
[0008]
Further, the control device outputs a terminal voltage of the DC brushless motor corresponding to a frequency command input based on a predetermined reference voltage / frequency pattern and a predetermined target phase difference. And a target phase difference calculating means, a voltage / current phase difference calculating means for calculating a phase difference between a terminal voltage and a current of the DC brushless motor, and a difference between the phase difference calculated by the voltage / current phase difference calculating means and the target phase difference. Phase-voltage conversion means for converting the phase error into a voltage error, and the voltage error converted by the phase-voltage conversion means so that the phase difference approaches the target phase difference. And an adder / subtractor for performing an addition / subtraction operation on the terminal voltage output from the operation means.
[0009]
Further, a switching circuit having a plurality of switching elements, and a DC voltage applying means for applying a DC voltage to the switching circuit, a DC voltage is converted to an AC voltage, a stator having a stator winding and a permanent magnet. A voltage-type inverter that supplies a voltage to a DC brushless motor composed of a rotor having a rotor, a zero-cross of a terminal voltage of the DC brushless motor, and a phase difference between a zero-cross of a current flowing through the DC brushless motor, and a voltage-type inverter is detected. The control device is provided with a control device for controlling and operation stop means for stopping operation when the phase difference exceeds a set value set in advance for each operation frequency.
[0010]
Also, a phase voltage detecting means for detecting potential difference information between an output terminal and an input terminal of the switching element, and a timing detection for detecting a state where both upper and lower switching elements of the same phase of the switching circuit are OFF and outputting as a timing signal. And a current polarity detecting means, which latches the potential difference information output by the phase voltage detecting means with a timing signal output by the timing detecting means and makes the current polarity signal a current polarity signal. The phase difference is calculated based on the polarity signal.
[0011]
Further, a microprocessor for driving the switching element is provided, and the timing signal detecting means and the latch means are constituted by H / W or S / W in the microprocessor.
[0012]
Further, a switching circuit having a plurality of switching elements, and a DC voltage applying means for applying a DC voltage to the switching circuit, a DC voltage is converted to an AC voltage, a stator having a stator winding and a permanent magnet. A voltage-type inverter that supplies a voltage to a DC brushless motor composed of a rotor having a rotor, a zero-cross of a terminal voltage of the DC brushless motor, and a phase difference between a zero-cross of a current flowing through the DC brushless motor, and a voltage-type inverter is detected. A control device for controlling; a current detecting means for detecting a current of the DC brushless motor; and if the detected current value detected by the current detecting means exceeds a set value set in advance for each operation frequency, the operation is stopped. Operation stop means.
[0013]
Further, a switching circuit having a plurality of switching elements, and a DC voltage applying means for applying a DC voltage to the switching circuit, a DC voltage is converted to an AC voltage, a stator having a stator winding and a permanent magnet. A voltage-type inverter that supplies a voltage to a DC brushless motor composed of a rotor having a rotor, a zero-cross of a terminal voltage of the DC brushless motor, and a phase difference between a zero-cross of a current flowing through the DC brushless motor, and a voltage-type inverter is detected. A control device for controlling, a current detecting means for detecting a current of the DC brushless motor, and a detected current value detected by the current detecting means, wherein a set value set to a different level in the low-speed operation frequency region and the high-speed operation frequency region is set. And an operation stop means for stopping the operation when the time is exceeded.
[0014]
Further, a switching circuit having a plurality of switching elements, and a DC voltage applying means for applying a DC voltage to the switching circuit, a DC voltage is converted to an AC voltage, a stator having a stator winding and a permanent magnet. A voltage-type inverter that supplies a voltage to a DC brushless motor composed of a rotor having a rotor, a zero-cross of a terminal voltage of the DC brushless motor, and a phase difference between a zero-cross of a current flowing through the DC brushless motor, and a voltage-type inverter is detected. A control device for controlling, a power detection means for detecting the power of the DC brushless motor, and an operation for stopping the operation when a detected power value detected by the current detection means exceeds a set value set in advance for each operation frequency. Stopping means.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
1 to 7 show the first embodiment. FIG. 1 is an overall configuration diagram of a driving device for a DC brushless motor. FIG. 2 is a diagram showing components of a current polarity detection circuit when a motor phase current is positive (inverter → motor). FIG. 3 is a signal waveform of each part of the current polarity detection circuit when the motor phase current is negative. FIG. 4 is a diagram showing the motor phase current and the current polarity signal. FIG. 5 is a block diagram of a DC brushless motor control. 6 is a diagram showing the relationship between the output frequency and the V / F voltage, and FIG. 7 is a control flow chart for step-out detection.
[0016]
In FIG. 1, 1 is a voltage type inverter, 2 is a DC brushless motor driven by the inverter 1, 3 is a control circuit which calculates and outputs a PWM control signal, and 4 is each of the inverters in the inverter 1 based on the control signal. A drive circuit for generating a signal for driving the switch, 5 is a phase voltage detecting means for detecting the phase voltage of the DC brushless motor 2, 6 is a timing detecting means, 7 is a motor based on the result of the phase voltage detecting means 5 and the timing detecting means 6. Is a latch means for outputting a polarity signal of the phase current (hereinafter referred to as a current polarity signal).
In the drawing, C1 to C6 are three-phase PWM signals output from the control circuit 3, and the subscripts correspond to the switching elements T1 to T6 in the inverter 1. C1 to C6 are sine-wave PWM signals provided with upper and lower arm short circuit prevention times (hereinafter referred to as Td) in advance. Z is a current polarity signal.
[0017]
Next, the basic operation of the sensorless control method for the inverter configured as described above will be described.
The control circuit 3 calculates PWM control signals C1 to C6 such that the inverter 1 outputs a predetermined frequency and voltage, and sequentially outputs them. The drive circuit 4 generates drive signals S1 to S6 for driving each switch in the inverter 1 based on the control signals C1 to C6. Inverter 1 opens and closes switches T1 to T6 based on drive signals S1 to S6, and generates an AC voltage at output terminals U, V, and W. As a result, power is supplied to the DC brushless motor 2 and the DC brushless motor 2 is driven.
[0018]
Here, for example, when it is necessary to drive the DC brushless motor 2 with high efficiency or high-precision rotation speed, the control circuit 3 detects the phase of the current flowing through the DC brushless motor 2 and generates an output voltage or frequency. There is a need to.
[0019]
Hereinafter, the operation of the step-out detection device will be described with reference to FIGS. 2 and 3, C1, C2, S1, S2, Vun, and Z are a U-phase upper arm control signal, a U-phase lower arm control signal, a U-phase upper arm drive signal, and a U-phase lower arm, respectively. A drive signal, a voltage between the U and N terminals, and a current polarity signal. Note that C1, C2, S1, and S2 are positive logic (the switch is ON when it is at a high level).
[0020]
2 and 3 show signal changes near the timing at which the inverter output voltage switches from HIGH (near Vdc) to LOW (near 0) during the U-phase PWM cycle.
Times a, b, c, and d indicate the timing of turning off C2, turning off S2, turning on C1, and turning on S1, respectively.
[0021]
As shown in FIG. 2, when the U-phase current flows in the positive direction, the U-phase current flows in the inverter 1 via either the upper-arm switching element T1 or the lower-arm diode. The selection depends on the state of the upper arm switching element T1. That is, if the upper arm drive signal S1 is ON, it passes through the switching element T1 of the upper arm (hereinafter referred to as state 1), and if it is OFF, it passes through the diode of the lower arm (hereinafter referred to as state 2).
[0022]
In the case of the state 1, the voltage Vun between the DC side terminal N and the U-phase terminal of the inverter 1 substantially generates the DC bus voltage Vdc (more precisely, the voltage obtained by subtracting the switch voltage drop Vce from the Vdc). In this case, Vun becomes almost zero voltage (more precisely, a voltage obtained by reducing the voltage drop VF of the diode). In the time chart of FIG. 2, it can be seen that the state changes from state 2 to state 1 at time d. When the voltage level of Vun that changes in this way is input and latched at a time before time d in FIG. 2 (for example, time c), a current polarity signal like Z in FIG. 2 is obtained. That is, a low-level current polarity signal signal is obtained after time c.
[0023]
When the U-phase current flows in the negative direction as shown in FIG. 3, the U-phase current flows through either the lower-arm switching element T1 or the upper-arm diode in the inverter. Depends on the state of the lower arm switching element T1. That is, if the lower arm drive signal S2 is ON, the signal passes through the switching element T1 of the lower arm (hereinafter referred to as state 3), and if it is OFF, the signal passes through the diode of the upper arm (hereinafter state 4).
[0024]
In the state 3, the voltage Vun between the DC side terminal N and the U-phase terminal of the inverter 1 generates almost zero voltage (accurately, the voltage obtained by adding the voltage drop Vce of the switch). The DC bus voltage Vdc (more precisely, a voltage obtained by adding the voltage drop VF of the diode to Vdc). In the time chart of FIG. 3, it can be seen that at time b, the state changes from state 3 to state 4. When the voltage level of Vun that changes in this way is input and latched at a time (for example, time c) after the timing at which Vun establishes a potential, a current polarity signal like Z in FIG. 3 is obtained. That is, a high-level signal is obtained after time c.
[0025]
As described above, since the current polarity signal Z changes so as to be low when the phase current is positive and high when the phase current is negative, the state of Z during the inverter cycle is approximately as shown in FIG. Is obtained.
[0026]
From the results of the phase voltage detecting means 5 for detecting the phase voltage of the DC brushless motor 2, the timing detecting means 6, and the phase voltage detecting means 5 and the timing detecting means 6, a polarity signal of the motor phase current (hereinafter referred to as a current polarity signal) is obtained. The current-voltage phase difference calculator 14 in the control circuit 3 shown in FIG. 5 calculates the voltage-current phase difference (zero-cross phase difference) θ from the current polarity signal Z obtained from the current polarity detection circuit constituted by the latch means 7 for outputting. Is calculated. The calculated voltage / current phase difference θ is compared with the reference V / F and the target phase difference θ * calculated by the target phase difference calculator 9 by the comparison calculator 10 to output a target phase difference error Δθ. The target phase error Δθ is amplified and calculated by the amplification calculator 11, and then converted into a voltage error ΔV by the phase / voltage converter 12 with reference to, for example, a table.
[0027]
The calculated voltage error ΔV corresponds to the reference V / F and the frequency command F * of the reference V / F pattern output from the target phase difference calculator 9 so that the phase difference θ approaches the target phase difference θ *. V * is subjected to an addition / subtraction operation by the addition / subtraction unit 13. At this time, it is assumed that the reference V / F pattern and the target phase difference θ * have been obtained in advance by a motor test. As described above, since the control circuit 3 controls the voltage / current phase difference θ to approach the target phase difference θ *, the sensorless high-efficiency operation of the DC brushless motor 2 can be realized.
[0028]
In the system as described above, if an excessive load is applied to the DC brushless motor 2 and the DC brushless motor 2 steps out, as shown in FIG. 6, even if the voltage V is slightly increased or decreased with respect to the target phase difference θ *, Since the voltage-current phase difference θ does not match the target value, the voltage V eventually sticks to the upper limit VH or the lower limit VL. Therefore, step-out can be detected by determining whether the voltage output from the inverter 1 is higher than the upper limit VH or lower than the lower limit VL. FIG. 7 is a control flowchart of this step-out detection.
[0029]
The drive device of the DC brushless motor according to the present embodiment includes a microprocessor that drives the switching elements T1 to T6, and the timing signal detection unit 6 and the latch unit 7 are configured by H / W or S / W in the microprocessor. It was done.
[0030]
Embodiment 2 FIG.
FIG. 8 is a diagram illustrating the second embodiment, and is a diagram illustrating a relationship between an electric frequency and a voltage-current phase difference. In the first embodiment, the step-out detection is described as an example in which the step-out is detected depending on whether the voltage output from the inverter 1 is higher than the upper limit VH or lower than the lower limit VL, as shown in FIG. In addition, a similar effect can be obtained as a system in which the step-out is determined when the voltage / current phase difference (zero-cross phase difference) exceeds a set value set for each operation frequency.
[0031]
Embodiment 3 FIG.
FIG. 9 shows the third embodiment, and shows the relationship between the electric frequency and the effective current value. As shown in the drawing, a similar effect can be obtained as a system including a current detector and determining that a step-out occurs when the detected current value of the current detector exceeds a set value set for each operation frequency.
[0032]
Embodiment 4 FIG.
FIG. 10 shows the fourth embodiment, and shows demagnetization characteristics at the time of step-out of the magnet. In the third embodiment, the system is provided with a current detector, and when the detected current value of the current detector exceeds a set value set for each operation frequency, the system is determined to be out of step. However, as shown in FIG. In consideration of the fact that the demagnetization characteristics at the time of step-out are linear with respect to the step-out current, step-out is divided into a frequency region (operation) where there is asynchronous operation and a frequency region where there is no asynchronous operation. A system for setting the current level may be used to avoid demagnetization in a certain frequency (operating) region when the operation is performed during asynchronous operation.
[0033]
Embodiment 5 FIG.
FIGS. 11 to 14 show a fifth embodiment. FIG. 11 is a block diagram of a driving device for a DC brushless motor. FIGS. 12 and 13 show that when a DC voltage changes, a detection current value due to a shunt resistor is affected by Td. FIG. 12A shows a change between a large DC voltage (FIG. 12A) and a small DC voltage (FIG. 12B); FIG. 14B shows a detected current value when the DC voltage is changed; It is a figure which shows the relationship with the electric power value at the time of and a step-out.
[0034]
In order to increase the efficiency of the DC brushless motor 2, the DC voltage is reduced during low rotation. Therefore, as shown in FIGS. 11 to 14, a power detector is provided so that a step-out can be detected even when the voltage is changed to a double voltage and a single voltage by the switch 15, and the detected power value of the power detector is set at each operating frequency. The system may be determined to be out of sync if the set value exceeds the set value for each.
When the DC voltage changes, the detection current value due to the shunt resistor changes between a large DC voltage and a small DC voltage due to the influence of Td. Step-out can be detected.
[0035]
【The invention's effect】
The drive device for a DC brushless motor according to the present invention, even when driving a DC brushless motor without using a position signal, does not match the zero-crossing phase difference between the voltage and the current with the target value and the terminal voltage exceeds the predetermined upper limit value. By providing an operation stopping means for stopping the operation when it is higher or lower than a predetermined lower limit, stable and highly accurate step-out detection of the DC brushless motor can be realized.
[0036]
In addition, by providing an operation stopping means for stopping the operation when the zero cross phase difference between the terminal voltage of the motor and the zero cross phase of the current flowing through the motor exceeds a set value set for each operation frequency, a high-precision DC brushless motor is provided. Step-out detection can be realized.
[0037]
Also, a phase voltage detecting means for detecting potential difference information between an output terminal and an input terminal of the switching element, and a timing detection for detecting a state where both upper and lower switching elements of the same phase of the switching circuit are OFF and outputting as a timing signal. And a current polarity detecting means, which latches the potential difference information output by the phase voltage detecting means with a timing signal output by the timing detecting means and makes the current polarity signal a current polarity signal. By calculating the zero-cross phase difference based on the polarity signal, a step-out detection circuit can be configured at low cost.
[0038]
Further, the timing signal detecting means and the latch means of the current polarity signal for detecting the zero-crossing phase difference are realized by H / W or S / W in the microprocessor for driving the switching element, so that the circuit can be formed at low cost.
[0039]
In addition, when the current value detected by the current detection means exceeds a set value set in advance for each operation frequency, the operation stop means for stopping the operation is provided, whereby stable out-of-step detection can be realized.
[0040]
In addition, when the detected current value detected by the current detecting means exceeds a set value set at a different level between the low-speed operation frequency region and the high-speed operation frequency region, the operation stop means for stopping the operation is provided. And high-speed step-out detection can be realized.
[0041]
Further, by providing an operation stopping means for stopping the operation when the detected power value detected by the power detector exceeds a set value set for each operation frequency, highly accurate step-out detection can be realized.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a first embodiment, and is an overall configuration diagram illustrating a driving device of a DC brushless motor.
FIG. 2 shows the first embodiment, and is a waveform diagram of each part when the motor phase current is positive.
FIG. 3 shows the first embodiment and is a waveform diagram of each part when the motor phase current is negative.
FIG. 4 shows the first embodiment and is a diagram showing a motor phase current and a current polarity signal.
FIG. 5 is a diagram showing the first embodiment, and is a block diagram of a control circuit of a driving device of the DC brushless motor.
FIG. 6 shows the first embodiment and is a diagram showing a relationship between an output frequency and a V / F voltage.
FIG. 7 is a diagram showing the first embodiment and is a control flowchart of step-out detection.
FIG. 8 shows the second embodiment, and shows the relationship between the electric frequency and the voltage-current phase difference.
FIG. 9 shows the third embodiment, and shows the relationship between the electric frequency and the effective current value.
FIG. 10 shows the fourth embodiment and is a diagram showing demagnetization characteristics at the time of step-out of a magnet.
FIG. 11 is a view showing a fifth embodiment, and is a configuration diagram of a driving device of a DC brushless motor.
FIG. 12 shows the fifth embodiment, and shows that when the DC voltage changes, the detected current value changes according to the DC voltage.
FIG. 13 shows the fifth embodiment, and shows that when the DC voltage changes, the detected current value changes according to the DC voltage.
FIG. 14 is a diagram illustrating the fifth embodiment, and is a diagram illustrating a relationship between an operation frequency and power values during normal operation and during step-out.
FIG. 15 is a configuration diagram showing a conventional DC brushless motor driving device.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 inverter, 2 direct current brushless motor, 3 control circuit, 4 drive circuit, 5 phase voltage detection means, 6 timing detection means, 7 latch means, 9 reference V / F and target phase difference calculator, 10 comparator, 11 amplifier , 12 phase / voltage converter, 13 addition / subtraction calculator, 14 voltage / current phase difference calculator, 15 switch.

Claims (8)

A switching circuit having a plurality of switching elements, and a DC voltage applying means for applying a DC voltage to the switching circuit, converting the DC voltage into an AC voltage, and having a stator having a stator winding and a rotor having a permanent magnet A voltage-type inverter that supplies a voltage to a DC brushless motor configured by:
The terminal of the DC brushless motor is detected by detecting a phase difference between a zero cross of a terminal voltage of the DC brushless motor and a zero cross of a current flowing through the DC brushless motor, so that the phase difference approaches a predetermined target phase difference. A control device for controlling the voltage of the voltage-type inverter,
In the control device, operation stop means for stopping the operation when the terminal voltage is higher than a predetermined upper limit or lower than a predetermined lower limit without the phase difference being equal to a target value,
A driving device for a DC brushless motor, comprising: The control device outputs a terminal voltage of the DC brushless motor corresponding to a frequency command input based on a predetermined reference voltage / frequency pattern and a predetermined target phase difference. And a target phase difference calculating means, a voltage / current phase difference calculating means for calculating a phase difference between a terminal voltage and a current of the DC brushless motor, a phase difference calculated by the voltage / current phase difference calculating means, and the target phase difference. Phase-voltage conversion means for converting a phase error, which is a difference between the two, into a voltage error, and the voltage error converted by the phase-voltage conversion means so that the phase difference approaches the target phase difference. 2. A direct current brush according to claim 1, further comprising an adder / subtractor for performing an addition / subtraction operation on said terminal voltage output from said frequency pattern and target phase difference calculation means. Sumota of the drive unit. A switching circuit having a plurality of switching elements, and a DC voltage applying means for applying a DC voltage to the switching circuit, converting the DC voltage into an AC voltage, and having a stator having a stator winding and a rotor having a permanent magnet A voltage-type inverter that supplies a voltage to a DC brushless motor configured by:
A control device that detects a phase difference between a zero cross of a terminal voltage of the DC brushless motor and a zero cross of a current flowing through the DC brushless motor, and controls the voltage-type inverter,
When the phase difference exceeds a set value set in advance for each operation frequency, operation stop means for stopping operation,
A driving device for a DC brushless motor, comprising: A phase voltage detecting means for detecting potential difference information between an output terminal and an input terminal of the switching element, and a timing for detecting a state in which both the upper and lower switching elements of the same phase of the switching circuit are OFF and outputting the same as a timing signal; A current polarity detection unit comprising: a detection unit; and a latch unit that latches a potential difference information output by the phase voltage detection unit with a timing signal output by the timing detection unit to obtain a current polarity signal.
4. The DC brushless motor driving device according to claim 1, wherein the phase difference is calculated based on the current polarity signal detected by the current polarity detection unit. 5. A DC brushless motor according to claim 4, further comprising a microprocessor for driving said switching element, wherein said timing signal detecting means and latch means are constituted by H / W or S / W in said microprocessor. Drive. A switching circuit having a plurality of switching elements, and a DC voltage applying means for applying a DC voltage to the switching circuit, converting the DC voltage into an AC voltage, and having a stator having a stator winding and a rotor having a permanent magnet A voltage-type inverter that supplies a voltage to a DC brushless motor configured by:
A control device that detects a phase difference between a zero cross of a terminal voltage of the DC brushless motor and a zero cross of a current flowing through the DC brushless motor, and controls the voltage-type inverter,
Current detection means for detecting the current of the DC brushless motor,
If the detected current value detected by the current detection means exceeds a set value set in advance for each operation frequency, operation stop means for stopping the operation,
A driving device for a DC brushless motor, comprising: A switching circuit having a plurality of switching elements, and a DC voltage applying means for applying a DC voltage to the switching circuit, converting the DC voltage into an AC voltage, and having a stator having a stator winding and a rotor having a permanent magnet A voltage-type inverter that supplies a voltage to a DC brushless motor configured by:
A control device that detects a phase difference between a zero cross of a terminal voltage of the DC brushless motor and a zero cross of a current flowing through the DC brushless motor, and controls the voltage-type inverter,
Current detection means for detecting the current of the DC brushless motor,
If the detected current value detected by the current detection means exceeds a set value set to different levels in the low-speed operation frequency region and the high-speed operation frequency region, operation stop means for stopping operation,
A driving device for a DC brushless motor, comprising: A switching circuit having a plurality of switching elements, and a DC voltage applying means for applying a DC voltage to the switching circuit, converting the DC voltage into an AC voltage, and having a stator having a stator winding and a rotor having a permanent magnet A voltage-type inverter that supplies a voltage to a DC brushless motor configured by:
A control device that detects a phase difference between a zero cross of a terminal voltage of the DC brushless motor and a zero cross of a current flowing through the DC brushless motor, and controls the voltage-type inverter,
Power detection means for detecting the power of the DC brushless motor,
If the detected power value detected by the current detection means exceeds a set value set in advance for each operation frequency, operation stop means to stop the operation,
A driving device for a DC brushless motor, comprising:

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