JP2000278985A - Driving device of dc brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a stable and speedy out-of-step detection method by stopping operation when a phase difference does not coincide with a target value and a terminal voltage is higher than a specific upper-limit value or lower than a specific lower-limit value. SOLUTION: An inverter 1 opens or closes switches T1-T6 based on drive signals S1-S6 of each switch in an inverter that is created based on the control signals C1-C6 and generates an AC voltage at output terminals U, V, and W. Then, power is supplied to a DC brushless motor 2 for driving. However, when an excessive load is applied to the DC brushless motor 2 for out-of-step, a voltage-current phase difference does not coincide with the target value even if the voltage is added or subtracted to or from the target phase difference, so that the voltage reaches an upper limit or a lower limit. Therefore, by deciding whether a voltage being outputted from the inverter 1 is higher than the upper limit or lower than the lower limit, the out-of-step can be detected, thus stably and accurately detecting the out-of-step of the DC brushless motor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensorless DC brushless motor driving apparatus, and more particularly to a step-out detecting apparatus for driving a DC brushless motor without using a position signal.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a configuration diagram showing a conventional DC brushless motor driving device disclosed in Japanese Patent Application Laid-Open Publication No. H10-115,004. 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; 29 is a shunt resistor 31 A forward current detection circuit for detecting a normal forward current flowing therein; 30 a current detection circuit having a forward current detection circuit 29 and a reverse current detection circuit 28;
Is a rectifier diode bridge, and 33 is a rectifier circuit having a diode bridge 32 and a smoothing capacitor.

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. 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.
Are sequentially switched, and the DC brushless motor 2 is driven.

In the inverter circuit 1, a shunt resistor 31 for current detection is connected to a connection line between a rectifier circuit 33 and a switching circuit 34, and a current detection circuit 30 is connected to both ends of the shunt resistor 31. This current detection circuit 30 is composed of a shunt resistor 31 and a forward current detection circuit 29.
A normal forward current flowing through the shunt resistor 31 is detected by the reverse current detecting circuit 28, and a reverse current flowing in the shunt resistor 31 in the reverse direction to the normal direction is detected. In such a case, the switching circuit 34 can be protected even during regenerative operation (during rapid deceleration, etc.).

[0005]

The step-out detecting method in the conventional DC brushless motor driving apparatus described above is based on the case where a back electromotive force is detected to generate a position signal or the case where a position signal is obtained by using a Hall IC or the like. However, when driving a DC brushless motor without using a position signal,
Because there is little difference between the current value during step-out and the current value during normal operation,
Due to the fact that step-out cannot be detected and the relationship between the demagnetization resistance of the DC brushless motor, there is an inconvenience when step-out needs to be detected at high speed.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and 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. It is an object of the present invention to provide a drive device.

[0007]

A DC brushless motor driving apparatus according to the present invention includes a switching circuit having a plurality of switching elements, and DC voltage applying means for applying a DC voltage to the switching circuit. A voltage-type inverter that converts a voltage into an AC voltage and supplies a voltage to a DC brushless motor composed of a stator having a stator winding and a rotor having a permanent magnet, a zero crossing of terminal voltage of the DC brushless motor, and a DC brushless A voltage-type inverter control device for detecting a phase difference between a zero-cross of a current flowing through the motor and a terminal voltage of the DC brushless motor so that the phase difference approaches a predetermined target phase difference; and , The terminal voltage is higher than the predetermined upper limit or lower than the predetermined value because the phase difference does not match the target value. Is lower than the value is obtained by a driving stopping means for stopping the operation.

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. / Frequency pattern and target phase difference calculating means, voltage / current phase difference calculating means for calculating a phase difference between terminal voltage and current of a DC brushless motor, phase difference and target phase difference calculated by the voltage / current phase difference calculating means Phase-voltage conversion means for converting the phase error, which is the difference between the phase error to the voltage error, and the voltage error converted by the phase-voltage conversion means so that the phase difference approaches the target phase difference. An adder / subtractor for performing an addition / subtraction operation on the terminal voltage output from the target phase difference calculation means.

A stator having a switching circuit having a plurality of switching elements and DC voltage applying means for applying a DC voltage to the switching circuit, converting the DC voltage to an AC voltage, and having a stator winding. A voltage-type inverter that supplies a voltage to a DC brushless motor composed of a rotor having a permanent magnet, a phase difference between a zero cross of a terminal voltage of the DC brushless motor, and a zero cross of a current flowing in the DC brushless motor, and detects a voltage. A control device for controlling the type inverter and operation stop means for stopping operation when the phase difference exceeds a set value set in advance for each operation frequency.

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 state where both upper and lower switching elements of the same phase of the switching circuit are OFF, and outputs as a timing signal. And a current polarity detecting means for latching the potential difference information output from the phase voltage detecting means with a timing signal output from the timing detecting means to obtain a current polarity signal. The phase difference is calculated based on the detected current polarity signal.

Also, a microprocessor for driving the switching element is provided, and the timing signal detecting means and the latch means are provided with H / W or S /
W.

A stator having 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 winding; A voltage-type inverter that supplies a voltage to a DC brushless motor composed of a rotor having a permanent magnet, a phase difference between a zero cross of a terminal voltage of the DC brushless motor, and a zero cross of a current flowing in the DC brushless motor, and detects a voltage. A control device for controlling the type inverter, a current detecting means for detecting the current of the DC brushless motor, and an operation when the detected current value detected by the current detecting means exceeds a set value set in advance for each operation frequency. Operation stop means for stopping the operation.

A stator having a switching circuit having a plurality of switching elements and DC voltage applying means for applying a DC voltage to the switching circuit, converting the DC voltage to an AC voltage, and having a stator winding; A voltage-type inverter that supplies a voltage to a DC brushless motor composed of a rotor having a permanent magnet, a phase difference between a zero cross of a terminal voltage of the DC brushless motor, and a zero cross of a current flowing in the DC brushless motor, and detects a voltage. A control device for controlling the type inverter, a current detecting means for detecting a current of the DC brushless motor, and a detected current value detected by the current detecting means are set to different levels in the low-speed operation frequency region and the high-speed operation frequency region. An operation stopping means for stopping the operation when the set value is exceeded is provided.

A stator having a switching circuit having a plurality of switching elements and 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 winding; A voltage-type inverter that supplies a voltage to a DC brushless motor composed of a rotor having a permanent magnet, a phase difference between a zero cross of a terminal voltage of the DC brushless motor, and a zero cross of a current flowing in the DC brushless motor, and detects a voltage. A control device for controlling the type inverter, power detection means for detecting the power of the DC brushless motor, and operation when the detected power value detected by the current detection means exceeds a set value set in advance for each operation frequency. Operation stopping means for stopping the operation.

[0015]

Embodiments of the present invention will be described below 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. 6 is a block diagram of a DC brushless motor control, FIG. 6 is a diagram showing a relationship between an output frequency and a V / F voltage, and FIG.

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 that calculates and outputs a PWM control signal,
4 is a drive circuit for generating a signal for driving each switch in the inverter 1 based on the control signal, 5 is a phase voltage detecting means for detecting a phase voltage of the DC brushless motor 2, 6 is a timing detecting means, and 7 is a phase voltage. Latch means for outputting a polarity signal of the phase current of the motor (hereinafter referred to as a current polarity signal) from the results of the detection means 5 and the timing detection means 6. 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 the upper and lower arm short circuit prevention time (hereinafter referred to as Td) in advance.
Is a sine wave PWM signal provided with. Z is a current polarity signal.

Next, the basic operation of the sensorless control system of the inverter configured as described above will be described. Control circuit 3
Calculates the 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. The inverter 1 opens and closes the switches T1 to T6 based on the drive signals S1 to S6, and generates an AC voltage at the output terminals U, V, W. As a result, power is supplied to the DC brushless motor 2 and the DC brushless motor 2 is driven.

Here, for example, when it is necessary to drive the DC brushless motor 2 with high efficiency or high rotational speed with high accuracy, the control circuit 3 detects the phase of the current flowing in the DC brushless motor 2 and outputs the output voltage or the output voltage. Need to generate frequency.

Hereinafter, the operation of the step-out detecting 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, a U-phase lower arm drive signal, and a U-N terminal voltage, respectively. , Current polarity signal. C1, C2, S1, S2
Is positive logic (when high level, the switch is ON).

The time charts of FIGS.
Inverter output voltage during M cycle is HIGH (Vdc
5 shows a signal change near the timing of switching from (near) to LOW (near 0). Times a, b, c, and d indicate the timing of turning off C2, turning off S2, turning on C1, and turning on S1, respectively.

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 of the current path depends on the state of the upper arm switching element T1. That is, if the upper arm drive signal S1 is ON, the signal passes through the switching element T1 of the upper arm (hereinafter referred to as state 1), and if the signal is OFF, it passes through the diode of the lower arm (hereinafter state 2).
).

In the state 1, the voltage Vun between the DC terminal N and the U-phase terminal of the inverter 1 is substantially a DC bus voltage Vdc (more precisely, a voltage obtained by subtracting the switch voltage drop Vce from Vdc). In the case of state 2, 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. That is, a low-level current polarity signal signal is obtained after time c.

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. The selection of the path depends on the state of the lower arm switching element T1. That is, if the lower arm drive signal S2 is ON, it passes through the switching element T1 of the lower arm (hereinafter referred to as state 3), and if it is OFF, it passes through the diode of the upper arm (hereinafter state 4).

In the state 3, the voltage Vun between the DC side terminal N and the U-phase terminal of the inverter 1 is almost zero voltage (more precisely, the voltage obtained by adding the voltage drop Vce of the switch). Vun is approximately the DC bus voltage Vdc (more precisely, the voltage obtained by adding the voltage drop VF of the diode to Vdc). FIG.
In the time chart of FIG.
It turns out that it changes to. 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 when Vun establishes a potential, a current polarity signal such as Z in FIG. 3 is obtained. That is, a high-level signal is obtained after time c.

As described above, the current polarity signal Z changes 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. 4, and a current polarity signal of the phase current is obtained.

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, the polarity signal of the motor phase current (hereinafter referred to as the current polarity signal) 5 from a current polarity signal Z obtained from a current polarity detection circuit constituted by a latch means 7 for outputting a voltage-current phase difference (zero-cross position) by a current-voltage phase difference calculator 14 in the control circuit 3 shown in FIG. (Phase difference) θ is calculated. The calculated voltage / current phase difference θ is compared and calculated by the comparison calculator 10 with the reference V / F and the target phase difference θ * calculated by the target phase difference calculator 9 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.

The calculated voltage error ΔV is determined by the frequency command F * of the reference V / F and 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 *. Is calculated by the addition / subtraction calculator 13. At this time, the reference V / F pattern and the target phase difference θ
* Is assumed to 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.

In the system 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, the voltage V is slightly increased or decreased with respect to the target phase difference θ *. However, 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.

The DC brushless motor driving apparatus according to the present embodiment includes a microprocessor for driving the switching elements T1 to T6, and the timing signal detecting means 6 and the latching means 7 are provided with H / W or S / W.

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 step-out is detected based on whether the voltage output from the inverter 1 is higher than the upper limit VH or lower than the lower limit VL. In addition, a similar effect can be obtained as a system in which it is determined that a step-out occurs when the voltage / current phase difference (zero-cross phase difference) exceeds a set value set for each operation frequency.

Embodiment 3 FIG. 9 shows the third embodiment, and shows the relationship between the electric frequency and the effective current value. As shown in the drawing, the same effect can be obtained as a system that includes a current detector and determines that a step-out occurs when the detected current value of the current detector exceeds a set value set for each operation frequency.

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 during step-out are linear with respect to the step-out current, step-out is divided into a frequency region 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 (operation) region when the operation is performed at the time of asynchronous operation.

Embodiment 5 FIG. 11 to 14 show a fifth embodiment. FIG. 11 is a configuration diagram of a driving device for a DC brushless motor. FIGS.
A diagram showing that the detection current value due to the shunt resistance changes when the DC voltage is large (FIG. 12A) and when the DC voltage is small (FIG. 12B) due to the influence of d. FIG. 14 is a diagram showing the relationship between the operating frequency and the power values during normal operation and during step-out.

In order to increase the efficiency of the DC brushless motor 2, the DC voltage is reduced during low rotation. Therefore, FIG.
As shown in FIGS. 14 to 14, even when the voltage is changed to the double voltage and the single voltage by the switch 15, the step-out can be detected.
A system may be provided that includes a power detector and determines that a step-out occurs when a detected power value of the power detector exceeds a set value set for each operation frequency. 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]

According to the DC brushless motor driving apparatus of the present invention, even when the DC brushless motor is driven without using the position signal, the terminal voltage does not match the zero-crossing phase difference between the voltage and the current. Is provided with an operation stop means for stopping the operation when is higher than a predetermined upper limit value or lower than a predetermined lower limit value, thereby achieving stable and highly accurate step-out detection of the DC brushless motor.

Further, by providing an operation stop means for stopping the operation when the phase difference between the zero crossing of the terminal voltage of the motor and the zero crossing of the current flowing through the motor exceeds a set value set for each operation frequency, a highly accurate DC Step-out detection of a brushless motor can be realized.

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 state where both upper and lower switching elements of the same phase of the switching circuit are OFF, and outputs as a timing signal. And a current polarity detecting means for latching the potential difference information output from the phase voltage detecting means with a timing signal output from the timing detecting means to obtain a current polarity signal. By calculating the zero-cross phase difference based on the detected current polarity signal, a step-out detection circuit can be configured at low cost.

The current polarity signal timing signal detecting means for detecting the zero-crossing phase difference and the latch means are provided in the microprocessor in the microprocessor for driving the switching element.
By realizing / W or S / W, a circuit can be configured at low cost.

When the detected current value detected by the current detection means exceeds a set value set in advance for each operation frequency, an operation stop means for stopping the operation is provided.
Stable step-out detection can be realized.

Further, there is provided an operation stopping means for stopping the operation 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. Thereby, stable and high-speed step-out detection can be realized.

Further, by providing an operation stop 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 chart 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, in which the output frequency and V /
It is a figure showing relation with F voltage.

FIG. 7 is a diagram showing the first embodiment and is a control flowchart of step-out detection.

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.

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 when a magnet loses synchronism.

FIG. 11 is a view showing a fifth embodiment, and is a configuration diagram of a drive 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 shows the fifth embodiment, and shows the relationship between the operating frequency and the 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 unit, 14
Voltage-current phase difference calculator, 15 switches.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazunori Sakanobe 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation In-house F-term (Reference) 5H560 BB04 DC11 DC12 DC13 DC20 JJ01 RR02 RR10 SS01 TT05 TT15 TT20 UA03 XA06 XA12

Claims (8)

[Claims] 1. A stator having 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 winding. A voltage-type inverter that supplies a voltage to a DC brushless motor composed of a rotor having a permanent magnet, and a zero cross of a terminal voltage of the DC brushless motor;
The voltage-type inverter control device that detects a phase difference between a zero crossing of a current flowing through the DC brushless motor and a terminal voltage of the DC brushless motor so that the phase difference approaches a predetermined target phase difference. And wherein the control device further comprises: operation stop means for stopping operation when the terminal voltage is higher than a predetermined upper limit value or lower than a predetermined lower limit value without the phase difference being equal to a target value. Characteristic DC brushless motor drive device. 2. 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. A reference voltage / frequency pattern and 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 phase difference calculated by the voltage / current phase difference calculating means. Phase-voltage conversion means for converting a phase error that is a difference from the target phase difference into a voltage error, and the voltage error converted by the phase-voltage conversion means such that the phase difference approaches the target phase difference. 2. An adder / subtractor for performing an add / subtract operation on the terminal voltage output from the reference voltage / frequency pattern and the target phase difference calculator. DC brushless motor drive device. 3. A stator having a switching circuit having a plurality of switching elements and 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 winding. A voltage-type inverter that supplies a voltage to a DC brushless motor composed of a rotor having a permanent magnet, and a zero cross of a terminal voltage of the DC brushless motor;
A control device that detects a phase difference between a zero cross of a current flowing in the DC brushless motor and controls the voltage-type inverter; and operates when the phase difference exceeds a set value set in advance for each operation frequency. And a drive stopping means for stopping the operation of the brushless DC motor. 4. A phase voltage detecting means for detecting potential difference information between an output terminal and an input terminal of the switching element, and a state in which both upper and lower switching elements in the same phase of the switching circuit are OFF, and A timing detection unit that outputs the signal as a signal; and a current polarity detection unit that includes a latch unit that latches the potential difference information output by the phase voltage detection unit with a timing signal output by the timing detection unit to generate a current polarity signal. 2. The phase difference is calculated based on the current polarity signal detected by the current polarity detection unit.
A driving device for a DC brushless motor according to claim 3. 5. A microprocessor for driving the switching element, wherein the timing signal detecting means and the latching means include an H / W in the microprocessor.
5. The driving device for a DC brushless motor according to claim 4, wherein the driving device is constituted by S / W. 6. A stator having a switching circuit having a plurality of switching elements and DC voltage applying means for applying a DC voltage to the switching circuit, converting the DC voltage to an AC voltage, and having a stator winding. A voltage-type inverter that supplies a voltage to a DC brushless motor composed of a rotor having a permanent magnet, and a zero cross of a terminal voltage of the DC brushless motor;
A control device that detects a phase difference between a zero crossing of a current flowing through the DC brushless motor and controls the voltage-type inverter; a current detection unit that detects a current of the DC brushless motor; and a current detection unit that detects the current. A drive device for a DC brushless motor, comprising: operation stop means for stopping operation when a detected current value exceeds a set value set in advance for each operation frequency. 7. A stator having a switching circuit having a plurality of switching elements and 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 winding. A voltage-type inverter that supplies a voltage to a DC brushless motor composed of a rotor having a permanent magnet, and a zero cross of a terminal voltage of the DC brushless motor;
A control device that controls the voltage-type inverter by detecting a phase difference between a zero crossing of a current flowing through the DC brushless motor, a current detection unit that detects a current of the DC brushless motor, and a current detection unit that detects the current. An operation stopping means for stopping the operation when the detected current value exceeds a set value set at a different level between the low-speed operation frequency region and the high-speed operation frequency region. apparatus. 8. A stator having a switching circuit having a plurality of switching elements and DC voltage applying means for applying a DC voltage to the switching circuit, converting the DC voltage to an AC voltage, and having a stator winding. A voltage-type inverter that supplies a voltage to a DC brushless motor composed of a rotor having a permanent magnet, and a zero cross of a terminal voltage of the DC brushless motor;
A control device that controls the voltage-type inverter by detecting a phase difference between a zero crossing of a current flowing through the DC brushless motor, a power detection unit that detects power of the DC brushless motor, and a current detection unit that detects the power. A drive device for a DC brushless motor, comprising: operation stop means for stopping operation when the detected power value exceeds a set value set in advance for each operation frequency.