JP2891044B2 - Drive circuit for brushless motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to starting of a brushless motor driving circuit for driving a brushless motor by detecting a relative position between the stator coil and a magnet rotor from a back electromotive voltage of the stator coil.

[0002]

2. Description of the Related Art A conventional drive circuit for a brushless motor is disclosed, for example, in Japanese Patent Application Laid-Open No. Sho 62-281791. This is a three-phase full-wave drive system, in which a Hall element detects magnetic flux of a magnet rotor, a position detection circuit inputs a three-phase position detection signal to a logic processing circuit, and controls a switching element to control a brushless motor. Is to be driven.

Further, as disclosed in Japanese Patent Application Laid-Open No. H4-161092, a relative position between a stator coil and a magnet rotor is detected by an induced voltage of a stator coil without using a position sensor such as a Hall element. There is also a sensorless drive circuit that controls a switching element based on the sensor and drives a brushless motor.

[0004]

In the above-mentioned conventional brushless motor driving circuit, the former is difficult to reduce the size and cost by the Hall element and the wiring associated therewith. It is shifting to a sensorless system. However, in the sensorless system, the startup is likely to be unstable, and for example, as described in
In Japanese Patent Application Laid-Open No. 161092, a capacitor is charged and discharged alternately to supply current and shake to start the apparatus. And the malfunction due to the noise at the time of turning on the switch is prevented by turning off electricity during that time,
Depending on the relative positional relationship of the magnet rotors at the time of starting, there is a problem in the reliability of starting in a predetermined direction.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to obtain a reliable start-up in a sensorless driving circuit.

[0006]

Driving circuit of the brushless motor according to claim 1 Means for Solving the Problems] is the driving circuit of the brushless motor of the sensorless method, 2 mode exchange the conduction mode of the fixing at a frequency required for fixation of the magnet rotor Repeat for a predetermined period of time or a predetermined number of times
Output to a specific switching element
Is fixed at the point where the torques in the two energizing modes balance.
An initial fixed signal generating circuit for synchronization signal generation for generating a synchronizing signal for starting the brushless motor forcibly
A circuit, and a startup circuit that controls the initial fixed signal generation circuit and the synchronization signal generation circuit at the time of startup and outputs one of the signals ,
The output of the position detection circuit and the output of the start-up circuit
A signal switching circuit for outputting any one of these inputs is provided,
Fixed by logic processing circuit based on output of signal switching circuit
Energize the stator coil in the energizing mode for
Adopt means.

[0007] a driving circuit of a brushless motor according to claim 2, the initial fixed signal generating circuit in said means according to claim 1, energizing the energization mode for <br/> fixed frequency necessary to fix the magnet rotor A means for alternately repeating the output for a predetermined time or a predetermined number of times with an OFF-off pattern interposed therebetween ;
adopt.

According to a third aspect of the present invention, there is provided a brushless motor driving circuit which performs PWM control in a sensorless system of two power supplies and two phases and full waves.
In controlling the energization of the stator coil more,
Energization for fixing at the frequency required for fixing the magnet rotor
The mode is alternately repeated two or more times for a specified time or a specified number of times
An initial fixed signal generation circuit that returns and outputs
Generates a synchronization signal for forcibly starting the
Signal generator and initial fixed signal generator at startup.
To generate one of the signals by controlling the
And an initial fixed signal generation circuit, especially a high potential
From the medium potential side to the low potential side
Energization should be such that the total energization time is approximately the same for each
Means for outputting the output signal.

[0009]

[0010]

According to the present invention, an initial fixed signal is generated.
The circuit is alternately and repeatedly a predetermined time or a predetermined number of pulses to output the two energization modes to particular transistor element
Accordingly, the magnet rotor is rotated in the normal and reverse directions, and the magnet rotor is fixed at a point where the torques in the respective energizing modes are balanced, and then the magnet rotor is started in a fixed direction by the synchronization signal.

According to the second aspect of the invention, the off-mode in which the current is not supplied is regularly interposed between the two power supply modes, so that the magnet rotor is fixed at the point where the torques in the power supply mode are balanced. However, because there is an off mode when the magnet rotor is swung left and right, it is not always accelerated by applying torque to either,
The part that swings by inertia increases.

According to the third aspect of the present invention, the initial fixed signal
The power supply from the high potential side to the medium potential side
And the energization time from the potential side to the low potential side respectively
Switching operation by PWM control because they are almost the same
Balance is less likely to collapse, and the power supply voltage is unbalanced
Can be prevented .

[0013]

[0014]

[Embodiment 1] FIG. 1 is a circuit diagram of a drive circuit for a sensorless brushless motor of a two-power-supply two-phase full-wave system according to an embodiment of the present invention. In the figure, reference numerals 1 and 2 denote an S-phase stator coil and an M-phase stator coil of a brushless motor, which together with a magnet rotor (not shown) constitute a motor body of the brushless motor. Reference numeral 3 denotes a voltage doubler rectifier circuit composed of a diode and a capacitor. The voltage doubler rectifier circuit converts an AC power supply into a doubled voltage and rectifies the doubled voltage.
4b is supplied to the S-phase stator coil 1 and the M-phase stator coil 2. Reference numeral 5 denotes a starting circuit, which includes an initial fixing signal generating circuit 6 for outputting an initial fixing signal having a frequency necessary for fixing the magnet rotor, and a synchronizing signal generating circuit 7 for outputting a synchronizing signal for forcibly starting after the initial fixing. Control and output any of those signals. Reference numeral 8 denotes a position detection circuit that detects the relative position of the magnet rotor from the back electromotive force of the S-phase stator coil 1 and the M-phase stator coil 2.
Reference numeral 9 denotes a signal switching circuit, which receives the outputs from the starting circuit 5 and the position detecting circuit 8 and discriminates whether it is one of the signals and outputs the signal. Reference numeral 10 denotes a logic processing circuit, which is a switching element which receives an output of the signal switching circuit 9 and forms a phase arm.
The transistors 11 , 12 , 13, and 14 are controlled to conduct or cut off.

In the drive circuit having the above configuration, the transistors 11, 12, 13, and 14 of each phase arm are sequentially turned on by the logic from the logic processing circuit 10, so that the S-phase stator coil 1 and the M-phase stator coil 2 are turned on. And the brushless motor rotates. That is, the transistor 11 is turned on by the base signal, and a current flows through the S-phase stator coil 1 from the high potential side to the middle potential side (this is referred to as S +). I do. Next, the transistor 12 is turned on by the base signal, a current flows through the M-phase stator coil 2 from the high potential side to the medium potential side (this is M +), and the transistor 12 is turned off after energizing for 90 degrees in phase. I do. Subsequently, the transistor 13 is turned on by the base signal, and a current flows through the S-phase stator coil 1 from the medium potential side to the low potential side (this is referred to as S−), and the phase becomes 9-phase.
After energization for 0 degree, the transistor 13 is turned off. Further, the transistor 14 is turned on by the base signal, a current flows through the M-phase stator coil 2 from the medium potential side to the low potential side (this is referred to as M−), and the transistor 14 is turned off after energizing for 90 degrees in phase. I do. By this operation, a rotating magnetic field is generated in a certain direction in the order of S +, M +, S−, M−, and the brushless motor rotates by repeating this series of operations.

The position detecting circuit 8 detects the position of the magnet rotor based on the back electromotive force generated in the M-phase stator coil 2 and the S-phase stator coil 1 when the motor is driven, and sends it to the logic processing circuit 10 via the signal switching circuit 9. Send a signal. The logic processing circuit 10 processes this signal and processes the transistors 11, 1
The energization switching timing is determined by the base signals 2, 13, and 14. At the start of startup, the S-phase stator coil 1 and M
Since no back electromotive voltage is generated in the phase stator coil 2, the position detection circuit 8 cannot detect an appropriate position of the magnet rotor. Therefore, the signal switching circuit 9 sends a signal from the activation circuit 5 to the logic processing circuit 10 instead of the position detection circuit 8.
The starting circuit 5 initially fixes the magnet rotor at a predetermined position by the initial fixing signal generating circuit 6, and then forcibly switches the energization by the synchronous signal generating circuit 7 to start the brushless motor.

That is, first, the conduction mode A of the initial fixed signal generation circuit 6 (the predetermined predetermined transistor 11
S + by ON and energization mode B (predetermined specification
An initial fixed signal for performing M-) by turning on the transistor 14 is sent to the signal switching circuit 9 for a predetermined time or a predetermined number of pulses. The logic processing circuit 10 which has input this through the signal switching circuit 9 performs signal processing to execute the energization modes A and B and fixes the magnet rotor at a predetermined position. Synchronizing signal of the synchronizing signal generating circuit 7 thereafter via the signal switching circuit 9 is input to the logic processing circuit 10, transistor capacitor 11 logic processing circuit 10 to handle this, 12,1
3 and 14 are driven to forcibly activate the magnet rotor. After the start, the logic processing circuit 1 is activated by the signal switching circuit 9.
The input to 0 is switched to the signal of the position detection circuit 8.
The energization modes A and B may be (M +) and (S-).

<Specific Example 1 of Energizing Mode> As shown in FIG. 2, the two energizing modes A and B are alternately repeated for a predetermined time or a predetermined number of pulses. Thus, the magnet rotor is fixed at the point where the torques in the energization modes A and B are balanced. However, since torque is always applied to either side, the vibration to the left and right is large, and it takes time to converge the vibration, and the fixing of the magnet rotor is slightly delayed.

<Embodiment 2 of energizing mode> As shown in FIG. 3, the two energizing modes A and B are alternately repeated for a predetermined time or a predetermined number of pulses while interposing an off mode C in which no current is applied. As a result, the magnet rotor is fixed at the point where the torques in the energization modes A and B are balanced. However, when the magnet rotor is swung right and left, the torque is always applied to one of the off-modes and acceleration. Rather, the part that swings by inertia increases. Therefore, the vibration at the fixed position is weakened, the time until the convergence of the vibration is shortened, and the fixing time of the magnet rotor is shortened.

<Embodiment 3 of energization mode> As shown in FIG. 4, the two energization modes A and B are alternately repeated at a low frequency (long energization time) for a predetermined time or a predetermined number of pulses at an initial stage. A predetermined time or a predetermined number of pulses are alternately repeated at a high frequency (short energization time). As a result, the magnet rotor is largely shaken in the energizing modes A and B at the low frequency, and after moving to the vicinity of the predetermined position, the magnet rotor is changed to the energizing modes A and B at the high frequency and is vibrated little by little. Will be fixed. Therefore, the fixing time of the magnet rotor can be shortened, and the dead center state of the magnet rotor can be avoided.

After fixing the magnet rotor as described above, the starting circuit 5 outputs a synchronizing signal which changes in at least a synchronizing frequency band determined by the rating of the brushless motor by the synchronizing signal generating circuit 7, and outputs the synchronizing signal via the logic processing circuit 10. Transistors 11, 12, 13, 14
Is controlled to execute a predetermined energization pattern, and the brushless motor is started.

Embodiment 2 FIG. This embodiment has a circuit configuration of a two-power-supply, two-phase full-wave system, and energizes the S-phase stator coil 1 and the M-phase stator coil 2 and energizes the S-phase stator coil 1 and the M-phase stator coil 2 during the startup sequence. Are performed by PWM control, and the basic configuration is
This is the same as the first embodiment. That is, FIG. 5 which shows the voltage doubler rectifier circuit 3 and the switching circuit portion in FIG.
In FIG. 6 and FIG.
When 1 is turned on, the S-phase stator coil 1 is energized by the current path (a). When the transistor 11 is turned off, a back electromotive force is generated due to the inductance of the S-phase stator coil 1, and the diode 17 is turned on for a period of time until the output is extinguished.
, A current flows through the current path (b) shown in the figure, and the capacitor 19 is charged. Next, when the transistor 13 is turned on, the S-phase stator coil 1 is energized by the current path (C) shown in FIG. When the transistor 13 is turned off, a counter electromotive force is generated due to the inductance of the S-phase stator coil 1, and a current flows through the current path (d) shown in FIG.
0 is charged. The same applies to the case of energizing the M-phase stator coil 2.

In this case, the energizing time of the current S + flowing through the S-phase stator coil 1 when the transistor 11 is turned on, the energizing time of the current M + flowing through the M-phase stator coil 2 when the transistor 12 is turned on, The conduction time of the current S- flowing through the S-phase stator coil 1 when the transistor 13 is turned on and the conduction time of the current M- flowing through the M-phase stator coil 2 when the transistor 14 is turned on are not averaged. , PWM control, the on / off times of the transistors 11, 12, 13, 14 are unbalanced, and the voltages of the capacitors 19, 20 charged by the generated back electromotive force are also unbalanced. Therefore, the initial fixed signal generation circuit 6 generates the current S +, the current M +,
An initial fixed signal in which the total energization times of the current S− and the current M− are almost the same is output, and the instability of the circuit operation is avoided. Other operations are the same as those of the first embodiment, and the description is omitted.

[0024]

As is apparent from the above description of the embodiment, according to the first aspect of the present invention, the two energizing modes are alternately switched for a predetermined time or a predetermined number of pulses and the switching element is set in advance.
By repeatedly outputting to the determined specific switching element , the magnet rotor is fixed at the point where the torques in each energizing mode are balanced and then started in a certain direction by the synchronization signal, and the sensorless brushless The reliability of starting the motor is improved.

According to the second aspect of the present invention, particularly, the off mode in which no current is supplied to each of the two power supply modes is regularly interposed. Therefore, when the magnet rotor is swung right and left, the inertia due to the off mode increases. Since the time required for the vibration to converge is reduced, the fixed time is shortened, and the start-up is quick and reliable.

According to the third aspect of the present invention, an initial fixed signal is generated.
Total energization time in each energization mode by raw circuit is almost the same
Therefore, the switching operation by PWM control
The power supply voltage is not unbalanced and unbalanced
Can be

[0027]

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a drive circuit of a sensorless brushless motor according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an energization mode by an initial fixed signal generation circuit of the present invention.

FIG. 3 is an explanatory diagram showing another energization mode by the initial fixed signal generation circuit of the present invention.

FIG. 4 is an explanatory diagram showing still another energization mode by the initial fixed signal generation circuit of the present invention.

FIG. 5 is a circuit diagram showing a configuration of a power supply circuit unit and a switching circuit of a drive circuit of a sensorless brushless motor according to an embodiment of the present invention.

FIG. 6 is a circuit diagram showing the configuration of a power supply circuit unit and a switching circuit of a drive circuit for a sensorless brushless motor according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 S-phase stator coil 2 M-phase stator coil 5 Starting circuit 6 Initial fixed signal generating circuit 7 Synchronous signal generating circuit 8 Position detecting circuit 9 Signal switching circuit 10 Logic processing circuit 11 Transistor 12 Transistor 13 Transistor 14 Transistor A Conducting mode B Conducting mode C Off mode

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazushi Motoki 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (72) Inventor Yuichi Fukase 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Co., Ltd. (72) Inventor Takahiro Hayakawa 3-40, Tegano Shimogane, Nakatsugawa City, Gifu Prefecture Mitsubishi Electric Engineering Co., Ltd. Nagoya Works Nakatsugawa Branch Office (56) References JP 4-109892 ( JP, A) JP-A-1-308192 (JP, A) JP-A-6-178581 (JP, A) JP-A-4-1611092 (JP, A) JP-A-5-103491 (JP, A) (58) ) Surveyed field (Int.Cl. ⁶ , DB name) H02P 6/18

Claims (3)

(57) [Claims] A relative position between a stator coil and a magnet rotor is detected from a back electromotive force of a multi-phase connected stator coil by a position detection circuit, and a switching element is controlled by a logic processing circuit based on the detected position to control the stator coil. a drive circuit for driving a brushless motor determines the energization timing to, repeated two modes alternately on a predetermined time or a predetermined number of times the energization mode of the fixing at a frequency required for fixation of the magnet rotor, pre of the switching element Decision
Output to the specified switching element.
The torque in the above two energizing modes balances the rotor
An initial fixed signal generation circuit for fixing at a point, a synchronization signal generation circuit for generating a synchronization signal for forcibly starting the brushless motor, and controlling the initial fixed signal generation circuit and the synchronization signal generation circuit at startup. A starting circuit for outputting any one of the signals, a signal switching circuit for receiving the output of the position detection circuit and the output of the starting circuit as inputs, and outputting any of the inputs, based on the output of the signal switching circuit; A drive circuit for a brushless motor, wherein the logic processing circuit supplies power to the stator coil in the fixing power supply mode. 2. The drive of the brushless motor according to claim 1.
A dynamic circuit, the initial fixed signal generating circuit is alternately repeated for a predetermined time or a predetermined number of times across the off pattern of energization mode to passing <br/> electricity off for fixed frequency necessary to fix the magnet rotor A drive circuit for a brushless motor characterized by outputting. 3. A two-power two-phase full-wave circuit configuration,
Stator coil and magnet
The relative position of the rotor is detected by a position detection circuit, and based on this,
Control of switching elements by logic processing circuit
To determine the timing of energizing the stator coil
The drive circuit that drives the
Set the energizing mode for fixing at the frequency necessary for fixing the rotor.
Repeat for a specified time or a specified number of times alternately in two or more modes
The initial fixed signal generation circuit and the brushless motor
Synchronous signal generation that generates a synchronous signal to start
The raw circuit and the initial fixed signal generation circuit
To generate one of the signals by controlling the
Operating circuit, the output of the position detecting circuit and the output of the starting circuit.
Input signal and output any of those inputs.
The issue switching circuit provided, based on the output of the signal switching circuit
PWM control by the logic processing circuit and energization for fixing
In the mode, the stator coil is energized.
In addition, the above-mentioned initial fixed signal generation circuit is a
Power supply to the ground potential side and power supply from the middle potential side to the low potential side.
A signal is output so that the total energization time is approximately the same.
A driving circuit for a brushless motor, characterized in that the driving force is applied.