JPH07274576A - Pre-drive circuit for brushless motor - Google Patents

Abstract

PURPOSE:To provide a pre-drive circuit, in which the driving system, etc., of a motor can be changed by programming and which has high general-purpose properties and is used for the brushless motor. CONSTITUTION:A signal for driving a brushless motor is formed on the basis of a signal transmitted over an input terminal 2 in the input terminal section 2 consisting of three input terminals, all terminals or partial terminals of which are supplied with a signal regarding the positional information of the brushless motor, and one input terminal supplied with a comparison signal to the signal transmitted over the input terminals and an output terminal section 3 composed of six output terminals, from all terminals or partial terminals of which the signal for driving the brushless motor is output. A programmable logic generating means 13 outputting a programmable logic to the output terminal 3 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive circuit for a DC brushless motor, and more particularly to a predrive circuit that enables a motor having a different drive system to be driven by changing a program.

[0002]

2. Description of the Related Art Conventionally, as disclosed in JP-A-4-295300 and JP-A-4-325898,
In driving the stepping motor, a drive circuit has been used which switches between two-phase excitation and 1-2-phase excitation drive methods according to the drive conditions during operation. Further, the PWM method of the drive circuit of the brushless motor is mainly the uniform width PWM on one side (either the upper side or the lower side) of the arm, and many have been released as driving ICs.

Further, the brushless motor drive IC has a fixed output logic and an interface for connecting a driver is determined. When the drive system is changed, the IC to be used does not match the interface specification externally. It had to be changed, increasing the circuit scale. Further, the drive circuit has been manufactured so as to grasp the operation point according to the model used, determine the constant of the control loop for vibration and noise, and stop using the frequency of the vibration.

In a brushless motor drive circuit for PWM control, a method for limiting current is disclosed in Japanese Patent Laid-Open No. 3-1173.
As disclosed in Japanese Patent Laid-Open No. 88, it is known that the output is asynchronously turned off when an overcurrent is detected, and the PWM control is restored with a clock having a carrier frequency immediately after the overcurrent disappears. Further, as disclosed in Japanese Patent Application Laid-Open No. 61-180595, there has been known a method of suppressing a current at startup by applying a predetermined low voltage by PWM at startup.

[0005]

In the conventional drive circuit,
Dedicated drive IC that can support a fixed drive system
However, if the IC can be used, the driving circuit can be downsized and the cost can be reduced. However, if the driving method is special, the general-purpose IC cannot be used and the cost of the driving circuit is increased. There was a problem that this would lead to an increase in circuit scale. For example, it is very difficult to drive different motor configurations such as a two-phase half-wave drive motor and a two-phase full-wave drive motor using a three-phase full-wave drive IC. And the drive circuit was different whether there was a magnetic pole sensor or not.

Further, when the output format of the driver is determined by the drive IC to be used and the output voltage (when the control voltage is different from the output voltage) or the output format is changed, it is necessary to install a special interface with the drive IC. There was a problem that there was. In addition, when the brushless motor is installed in a product and driven under certain load conditions, it may resonate in the product's case and generate large vibrations or noise. However, there is a problem that it is necessary to take measures for each product, such as changing the value or changing the operation point of the motor.

Further, in overcurrent protection, when the timing of PWM recovery is the same at the time of start-up or overload when it is easy to detect an overcurrent, a sound corresponding to the frequency may be generated, and the countermeasure is easy. It wasn't something. As described above, conventionally, in order to reduce the size and cost of the brushless motor drive circuit, it is necessary to develop a dedicated IC in accordance with the drive system and the characteristics of the product, and it takes time to develop the IC. It was a cause of cost increase.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a pre-drive circuit for a brushless motor, which can change the driving method of the motor by programming and has a high versatility. To do.

[0009]

A brushless motor pre-drive circuit according to a first aspect of the present invention includes three input terminals and input terminals to which signals relating to position information of the brushless motor are supplied to all terminals or some terminals. From the input terminal part consisting of one input terminal to which the comparison signal to the signal supplied to the terminal is supplied, and the signal for driving the brushless motor is output from all terminals or part of the terminals Generates a signal for driving the brushless motor based on the output terminal section and the signal supplied to the input terminal.
The programmable logic generating means for outputting to the output terminal is provided.

In the brushless motor pre-drive circuit according to the second invention, the programmable logic generating means is
Furthermore, it has a function of outputting a PWM control signal for controlling the PWM duty and a PWM superimposition selection signal for selecting superimposition of the PWM signal for each output signal output from the output terminal. PWM signal output means for outputting a PWM signal based on the above, and a predetermined output signal output from the output terminal based on the PWM superposition selection signal
PWM superimposing means for superimposing signals. In the brushless motor pre-drive circuit according to the third aspect of the invention, the programmable logic generating means further has a function of outputting a positive / negative logic selection signal for selecting the logic for each output signal output from the output terminal. And a positive / negative logic selection means for changing the logic of the output signal output from the output terminal based on the positive / negative logic selection signal.

In the brushless motor pre-drive circuit according to the fourth aspect of the present invention, the programmable logic generating means is
Further, it has a function of outputting an output state selection signal for selecting the output form for each output signal output from the output terminal, and based on the output state selection signal, an output signal output from the output terminal. And an output form selecting means for changing the output form of. The brushless motor pre-drive circuit according to the fifth aspect of the present invention includes a communication terminal, and the programmable logic generation means further has a function of exchanging data with the outside through the communication terminal.

A brushless motor pre-drive circuit according to a sixth aspect of the present invention includes a current input terminal to which a signal relating to a current flowing through a coil of the brushless motor is input,
The M signal output means further includes a PW when an overcurrent flows through the coil, based on the signal input from the current input terminal.
The programmable logic generation means has a function of stopping the output of the M signal, and the programmable logic generation means further outputs the PWM signal from the PWM signal output means after the output of the PWM signal has stopped for a predetermined time. It has a function of outputting a signal.

In the brushless motor predrive circuit according to the seventh aspect of the present invention, the programmable logic generating means is
Furthermore, the rotation speed of the brushless motor is detected based on the signal supplied to the input terminal, the rotation speed is N, the electromotive force constant of the brushless motor is K _E , the coil resistance of the brushless motor is R, and the PWM signal is based on the PWM signal. When the applied voltage generated in the coil of the brushless motor is V and the maximum value of the drive current of the brushless motor is I _MAX , I
_MAX = (V−K _E N) / R is a constant value, and the PWM duty for generating the applied voltage V is the maximum value, and PW
It controls the M control signal. A brushless motor pre-drive circuit according to an eighth aspect of the present invention is an IC of the brushless motor pre-drive circuit.

[0014]

According to the first aspect of the invention, the input terminal section has three input terminals to which signals related to position information of the brushless motor are supplied to all terminals or a part of the terminals, and a comparison signal to the signals supplied to the input terminals. Is supplied to the output terminal portion, and the output terminal portion is composed of six output terminals from which a signal for driving the brushless motor is output from all terminals or a part of the terminals. A signal for driving the brushless motor is generated based on the signal supplied to the input terminal and output to the output terminal.

In the second aspect of the invention, the programmable logic generating means further selects the PWM control signal for controlling the PWM duty and the PWM for selecting the superimposition of the PWM signal for each output signal output from the output terminal. The superimposition selection signal is output, and the PWM signal output means outputs the PWM signal based on the PWM control signal.
The WM superimposing means superimposes the PWM signal on a predetermined output signal output from the output terminal based on the PWM superimposition selection signal.

In the third invention, the programmable logic generating means further outputs a positive / negative logic selection signal for selecting the logic for each output signal output from the output terminal, and a positive / negative signal. The logic selection means changes the logic of the output signal output from the output terminal based on the positive / negative logic selection signal. In the fourth invention, the programmable logic generation means further outputs an output state selection signal for selecting an output form for each output signal output from the output terminal, and outputs the means by the output form selection. The output form of the output signal output from the output terminal is changed based on the state selection signal.

In a fifth aspect, a communication terminal is provided,
Then, the programmable logic generating means further exchanges data with the outside through the communication terminal. According to the sixth aspect of the invention, the brushless motor includes a current input terminal to which a signal related to the current flowing in the coil is input, and the PWM signal output means further causes the coil to generate an overcurrent based on the signal input from the current input terminal. , The output of the PWM signal is stopped, and the programmable logic generating means further causes the PWM
After the output of the signal is stopped and a predetermined time has elapsed, the PWM signal output means outputs the PWM enable set signal for outputting the PWM signal.

In the seventh invention, the programmable logic generating means further detects the rotation speed of the brushless motor based on the signal supplied to the input terminal, and the rotation speed is N, and the electromotive voltage constant of the brushless motor is detected. K _E ,
The coil resistance of the brushless motor is R, the applied voltage generated in the coil of the brushless motor based on the PWM signal is V,
When the maximum value of the drive current of the brushless motor is I _MAX , the PWM duty for generating the applied voltage V is such that I _MAX = (V−K _E N) / R becomes a constant value with respect to the rotation speed N.
The PWM control signal is controlled with the tee as the maximum value. In the eighth invention, the pre-drive circuit for the brushless motor is integrated into an IC.

[0019]

【Example】

Example 1. FIG. 1 is a block diagram showing the configuration of a brushless motor pre-drive circuit according to an embodiment of the present invention. In the figure, 1 is a pre-drive circuit, which is integrated into an IC. Reference numeral 2 is an input terminal for detecting a magnetic pole, 3 is a main circuit switching element drive output terminal that outputs a drive signal for driving a switching element, and 4 is a buffer for the output signal of the main circuit switching element drive output terminal 3, which is a brushless It is a circuit that generates the voltage and current necessary to drive the switching element that drives the motor. 5 is an EXOR circuit, 6 is an AND circuit, 7 is an OR circuit, 8 is an AND circuit, 9 is a comparator or a magnitude comparator (in the case of digital), 10 is an analog or digital triangular wave generation circuit, 11 is a D flip-flop, and 12 is comparator,
Reference numeral 13 is a programmable logic generation circuit in which an output signal with respect to an input signal is changed by changing a program, 14 is a comparator, and 35 is an E ² PROM.

Next, the operation of this embodiment will be described. First, the input terminal 2d is connected to the comparators 14, 15, 1
Signals from the input terminals 2a, 2b and 2c are input to the comparators 14, 15 and 16, respectively, and are Hi and Lo with respect to the comparison voltage of the input terminal 2d.
The w signal is converted into a digital signal, and three signals 17 are input to the programmable logic generation circuit 13. The signals input from the input terminals 2a, 2b, 2c may be magnetic pole sensor signals or motor induced voltages, and the input may be selected according to the driving method.

Then, by changing the program of the programmable logic generation circuit 13 according to the driving system, the 6 output signals 24 for the 3 inputs 17 from the comparators 14, 15 and 16 and the forward / reverse rotation command 19 are determined. To be done. This output enters the buffers 4a-4b through AND circuits 6a-6f and EXOR circuits 5a-5f, and is output from the main circuit switching element drive output terminal 3.
Six outputs from the main circuit switching element drive output terminal 3 are pre-drive signals capable of driving the three-phase full bridge of the brushless motor. Also, some motor systems have only two arms, but the configuration is such that six outputs can be output so that a motor of up to three phases can be driven.

The PWM control input 20 is a motor driven PW.
It is a signal that controls M Duty and is the STAR of the motor.
It is a command input for performing T, STOP, speed control, and torque control. When the PWM control input 20 is input to the programmable logic generator 13, the programmable logic generator 13 generates a comparison level signal 21 and inputs it to the comparator 9. Then, the triangular wave generation circuit 10
P is obtained by comparing the signal 31 from
A WM ON / OFF Duty signal 33 is generated.

The signal 33 is input to the OR circuit inputs 7a to 7f through the AND circuit 8 and is ORed with the PWM superimposition selection signal 25 output from the programmable logic generation circuit 13 to select the PWM superimposition terminal. To be done. Select the PWM superimposition terminal by selecting the PWM superimposition selection number 2.
If 5 is High, the PWM ON / OFF Duty signal 33 is blocked by the OR circuit 7 and PWM modulation is not applied.
When the PWM superimposition selection signal 25 is Low, PWM is ON,
The OFF Duty signal 33 passes through the OR circuit 7 and is ANDed by the AND circuit of the 6 output signal 24 and 6a to 6f, and the PWM modulation is performed only on the output terminal for which the PWM superimposition is selected.

The outputs of the AND circuits 6a to 6f are EXO.
EX / OR with the positive / negative logic selection signal 26 in the R circuits 5a-5f
Is taken. Positive / negative logic selection signal 2 by EXOR logic
When 6 is High, the outputs of the AND circuits 6a to 6f are inverted and the signal for turning on the elements becomes Low. When the positive / negative logic selection signal 26 is Low, the AND circuit 6a
Since the outputs of ~ 6f do not change and become the outputs 37 of the EXOR circuits 5a-5f, the signal for turning on the elements remains High. In this way, by the positive / negative logic selection signal 26,
Either the positive or negative logic of the 6 outputs from the main circuit switching element drive output terminal 3 can be selected.

To select either positive or negative logic, for example, as shown in FIG. 2A, the PNP transistor 12 is placed with the output stage (arm) for driving the motor coil as the upper stage.
0, when the NPN transistor 121 is connected in the lower stage,
In order to turn on the upper PNP transistor 120 and flow a current into the motor coil, the output signal 3a must be Low, and the signal logic must be negative logic. Also,
In order to turn on the lower NPN transistor 121 and draw the current from the motor coil, the output signal 3b must be High level, and the signal logic must be positive logic. Although it is necessary to change the logic of the output signal 3 depending on the configuration of the output stage as described above, it is possible to easily change the logic of the output signal 3 by setting the positive / negative logic selection signal 26 as described above. Becomes

In addition, the output state selection signal 27 from the programmable logic generation circuit 13 is applied to the buffers 4a to 4f.
Is input, the output form can be selected from push-pull type, open drain or open collector type. Here, the operation of selecting either the push-pull type or the open drain or open collector type as the output form in the buffers 4a to 4f will be described. FIG. 3 is a circuit diagram showing an example of the configuration of the buffer 4. In the figure, reference numeral 37 is a drive signal for driving the external power element, and the PWM signal may be superimposed. 27 is an output state selection signal. First, when the output state selection signal is Low, the drive signal 37
Is high, the NPN transistors 108 and 109 are turned on via the resistors 110 and 111.

Then, the collector voltage of the transistor 108 becomes approximately 0 V, and the two PNP transistors 102 and 103 having the Dielington configuration are turned off.
When the transistor 109 is turned on, the power supply voltage Vcc changes from the emitter, the base, and the resistor 1 of the PNP transistor 100.
A current flows through the transistor 05 to turn on the transistor 100, and the collector ionization current of the transistor 100 is injected into the base of the transistor 101 to turn on. That is, the output to the output terminal 3 is at a high level so that a current as much as possible can drive the external power element.

When the output state selection signal is Low and the drive signal 37 is Low, the transistors 108,
Since both 109 are turned off, a current flows from the power supply Vcc to the base of the transistor 102 through the resistor 107, and the Darlington transistors 102 and 103 are turned on.
On the other hand, in the upper transistors 100 and 101, since the transistor 106 is off, no current flows to the base and
It is in the FF state. Therefore, the output 3 can draw a current enough to drive the external power element at the Low level. In this way, a signal at the same level as the drive signal 37 is output to the output terminal 3 (the output stage is a push-pull type). However, when the output state selection signal 27 is High, the transistor 109 is turned on via the resistor 112, so that the transistor 1 does not depend on the level of the output signal 37.
06 is turned off. As a result, the upper transistors 100 and 101 in the output stage are always turned off, so that the output terminal 3 has an open collector output.

As described above, the output state selection signal 27 can select the push-pull or open collector output state. In addition, the output signal is the upper transistor 1
In addition to the above-mentioned method, an analog switch is connected in series with the resistor 111 so that the signal is not transmitted to the 106 transistors, or the upper and lower transistors are driven by independent drive signals. When operating and selecting open drain or open collector, the method of turning off the upper stage transistor drive signal may be adopted.

This push-pull type or open drain or open collector type is selected when the output stage power supply voltage is higher than the power supply voltage Vcc of the pre-driver as shown in FIG. Signal is H
The PNP transistor may be turned on even at the high level, and in such a case, even if the pre-driver power supply voltage and the output stage power supply voltage are different by changing the output state from push-pull to open collector, the output state selection signal 27 It becomes possible to deal with it easily by setting.

Input signal 2 from the overcurrent detection terminal
In reference numerals 8 and 29, 29 is a comparison level and 28 is a current detection signal. When the current detection signal 28 becomes higher than the comparison level 29, the comparator 12 causes the overcurrent detection signal 30 to become High.
It becomes the h level, the overcurrent detection signal 30 is input to the reset terminal of the D flip-flop 11, and when the overcurrent detection signal 30 is at the high level, the PWM enable signal 32 becomes Low asynchronously. Here, the PWM enable signal 32 and the PWM ON / OFF duty signal 3
Since 3 is ANDed by the AND circuit 8, when the PWM enable signal 32 becomes Low, the AND output 34 becomes L
It becomes ow, the output controlled by PWM is turned off, and the PWM control is not performed.

The inverted signal 23 of the PWM enable signal 32 output from the D flip-flop 11 is input to the programmable logic generation circuit 13, and the PWM enable set signal 22 is set to High level by a preprogrammed method. After that, it returns to the Low level. The PWM control is restored by the PWM enable set signal 22. By programmable the time until the PWM recovery, it is possible to reduce the noise due to the switching sound generated when the overcurrent is continuously generated.

Further, this PWM enable set signal 2
When the PWM carrier frequency is high, the output of 2 may not be supported by programmable software processing, and an example of the hardware configuration in that case is shown in FIG.
FIG. 5 is a time chart showing each input / output waveform during the output operation of the PWM enable set signal 22. Even in this case, software processing may be used as long as the processing can be performed by software.
In the figure, 38 is initial data that determines the time to recover from the overcurrent. SR _{1 to} SRn are n shift registers, 1
Reference numeral 30 denotes a random logic, which operates as follows when the input randomize signal is Low.

First, by the overcurrent detection inputs 28 and 29,
When an overcurrent is detected as shown in FIG.
As shown in (c), the inverted signal 23 of the PWM enable signal from the D flip-flop 11 becomes High level. Inverted signal 23 of PWM enable signal is High
At the h level, in synchronization with the clock 136 input to the random logic 130 shown in FIG.
As shown in FIG. 5G, one pulse of the data load signal 134 for loading the initial data 38 into the shift register is generated.

Thereafter, as shown in FIG. 5H, a clock pulse 133 for shifting the contents of the shift register to the next register is generated to shift the initial data one after another to the next register. When the first High of the initial data reaches the shift register SRn, one pulse of the PWM enable set signal 22 is output as shown in (d) of FIG. Further, when the PWM enable set signal 22 is output, the clock pulse 133 stops. Then, as one pulse of the PWM enable set signal 22 falls, the inverted signal 23 of the PWM enable signal becomes Low level as shown in FIG. 5C.

Thus, while the inverted signal 23 of the PWM enable signal is at the high level, the ON / OFF Duty signal 33 shown in FIG. 5B is not output from the AND circuit 8 and the (e) of FIG. ), And the PWM
It is out of control. Therefore, according to the initial data 38,
It is possible to freely change the return time to the PWM control.

When randomizing the recovery time from the overcurrent, when the randomize signal 135 is set to High, the random logic inputs the initial data only once to the shift register. After that, when the inverted signal 23 of the PWM enable signal is input at High, the random logic then generates a clock pulse 133 that shifts the contents of the shift register to the next register, and shifts the initial data one after another to the next register. Data of shift register SRn, that is, PWM enable set signal 2
2 is subjected to EXOR by SRn-1 via the AND circuit 132 and the EXOR circuit 131, and the result becomes the next data of SRn.

This circuit can generate 2 ⁿ -1 cycles of pseudo-random High and Low data, and the time when High data is generated in the shift register SRn and the PWM enable set signal 22 is generated becomes random. . The operation of stopping the clock pulse after the PWM enable set signal 22 is generated is the randomize signal 135.
Is the same as when Low is Low.

When a large amount of PWM periodic OFF is generated as a switching sound due to such an operation as the switching sound, the noise level is audibly reduced by shifting the cycle up and down, or the cycle is dispersed. The periodic sound can be eliminated with.

The E ² PROM 35 is the predriver 1
The E ² PROM communication terminal 36 is connected with four signal lines, and the programmable logic generator 13 is connected to the E ² PR
It is designed to communicate with the OM35 via the communication line 18,
² Based on the data written in the PROM 35, the brushless motor is drive-controlled under the special operating conditions or avoiding the operation at the resonance point peculiar to the device equipped with the brushless motor. Also,
The motor self-diagnosis result and cumulative operating time are reported by E ² PR.
It is designed to be stored in the OM35. This E ² P
The ROM communication terminal 36 can also communicate with a main controller (not shown) that controls the brushless motor. In that case, even if there is no PWM control input 20 or forward / reverse rotation command 19, the main controller's instruction can be sent. ²
It is possible to drive and control the brushless motor by inputting from the PROM communication terminal 36.

Data for avoiding operation at the resonance point peculiar to the brushless motor-equipped device written in the E ² PROM 35 will now be described. FIG. 6 is an explanatory diagram for explaining operation avoidance at a resonance point peculiar to a device equipped with a brushless motor. For example, when the brushless motor is rotating, as shown in (a) of FIG. 6, when there are rotation speeds N ₁ and N ₂ of the motor, the product noise remarkably increases due to the resonance of the product casing. E ² P in advance
In the ROM 35, data of the rotational speeds Na, Nb, Nc and Nd around the resonance rotational speeds N ₁ and N ₂ are written.

Then, the programmable logic generation circuit 13 of the pre-driver 1 uses the data of the rotation speeds Na, Nb, Nc and Nd written in the E ² PROM 35 as E ² PR.
Based on the data read from the OM communication terminal 36,
The rotation speed command N ^* from the motor controller is Na <N
^When < ^* Nb, the actual control speed is set to Na as shown in FIG. 6 (b) so that the speed does not cause resonance, and when N *> Nb, the command is issued again. The rotation speed control is performed so that the rotation speed matches the actual control rotation speed. As described above, based on the data written in the E ² PROM 35, it is possible to avoid the motor drive at the rotational speed N ₁ having resonance and reduce the noise of the product. Further, the operation is similar to the rotation speed N ₁ even at the rotation speed N ₂ having resonance. And even if the motor characteristics vary,
By changing the data written in the E ² PROM 35, the basic program of the programmable logic generation circuit 13 can be shared.

The programmable logic generator 13 can be easily realized by incorporating a microcomputer as a core. Generally, when a brushless motor is controlled by a microcomputer, a microcomputer capable of high speed processing is required. In this embodiment, as the pre-driver configuration, high-speed processing such as PWM control and overcurrent limitation is processed by dedicated hardware, so that the processing capacity of the microcomputer can be made relatively small. Further, a portion requiring high processing speed may be configured by a dedicated logic.

Next, an example of connection of the pre-drive circuit 1 of this embodiment in the drive circuit of the brushless motor will be described. FIG. 7 is a configuration diagram of a drive circuit of a three-phase full-wave drive brushless motor when a Hall IC is used as a magnetic pole sensor. In the figure, 1 is a pre-drive circuit,
54, 55, and 56 are Hall ICs, which are located around the rotor 53.
The magnetic pole position of the rotor 53 is detected every 20 ° or 60 °. The signals detected by the Hall ICs 54, 55, 56 are already high and low level digital signals, but the power supply voltage is input to the input terminal 2d and the comparison voltage divided by the resistors 57, 58 is input to the input terminals 2a to 2c. The Hall IC output signal is input to and digitized again in the predrive circuit 1.

A predrive signal for rotating the rotor in a predetermined rotation direction is output from the rotor magnetic pole signal input to the predrive circuit 1 from the main circuit switching element drive output terminals 3a to 3f to output the three-phase motor. The six transistors 59 to 64 that drive the U-phase coil 52, the V-phase coil 51, and the W-phase coil 50 are ON / OFF controlled, and the motor rotor rotates in a predetermined direction. Further, in order to control the rotation speed of the rotor, three arm upper transistors or lower transistors are turned on and off by a PWM modulation signal.
Since FF control is sufficient, 3a, 3c, 3e or 3b,
The PWM superimposition selection signal 25 of the programmable logic generator 13 shown in FIG. 1 is set so as to superimpose the PWM signal on 3d and 3f.

Example 2. This embodiment shows another example of the connection of the pre-drive circuit 1 in the drive circuit of the brushless motor. FIG. 8 is a configuration diagram of a drive circuit of a method of detecting a magnetic pole position from an electromotive voltage of a motor coil. This is called a sensorless brushless motor drive system.

In this embodiment, a neutral point voltage (which may be a virtual neutral point) of a three-phase motor coil, which is filtered by a resistor 65 and a capacitor 66, is input to the input terminal 2d as a comparison voltage, and each phase is inputted. Coil voltage for each resistance 6
The substantially electromotive voltage waveforms filtered by 7, 68, 69 and capacitors 70, 71, 72 are input to the input terminals 2a to 2c and used as magnetic pole position signals to rotate the rotor in the direction of rotation with respect to the input signals. The energization pattern of the motor coil is the main circuit switching element drive output terminals 3a to 3f
The six transistors 59 to 64 for driving the U-phase coil 52, the V-phase coil 51, and the W-phase coil 50 of the three-phase motor are ON / OFF controlled, and the motor rotor rotates in a predetermined direction. The operation of rotating this motor in a predetermined direction is the same as that in the first embodiment.

However, in the case of sensorless drive, the magnetic pole of the rotor magnet cannot be detected until the motor reaches a predetermined rotation and generates an electromotive voltage. Therefore, until the magnetic pole can be detected, the main circuit switching element is operated in an appropriate sequence. It is necessary to output a signal from the drive output terminals 3a to 3f to start the rotor. Such a sequence also corresponds to the programmable logic generator 13. In addition, as a variable speed control method of the rotor, the first embodiment
Is the same as.

Example 3. This embodiment shows another example of the connection of the pre-drive circuit 1 in the drive circuit of the brushless motor. FIG. 9 is a configuration diagram of a drive circuit when a two-phase motor is driven without a sensor. When two-phase full-wave drive is used, four output arms are required.
81 DC power supplies are arranged in series, and a two-phase coil 8 is placed at the middle point.
It can be driven by two arms by connecting 2,83. In this case, there are four transistors 84, 85, 86, 87 for energizing the motor coils 82, 83, and the main circuit switching element drive output terminals 3a-3.
Of the 6 output terminals of f, 4 output terminals will be used.

In addition, the rotor position detecting method is the same as in the second embodiment.
It is the same as the three-phase full-wave sensorless drive system shown in FIG.
The signal filtered by is input to the comparison input terminal 2d, and the coil voltage of each phase is input to the resistors 91 and 92 and the capacitor 9 respectively.
Input terminal 2 with the substantially electromotive voltage waveform filtered by 4, 93
a and 2b, which are used as magnetic pole position signals, generate drive signals at 4 output terminals 3a to 3d among the 6 output terminals of the main circuit switching element drive output terminals 3a to 3f to turn on the transistors 84 to 87, The rotor is rotated by controlling OFF.

Since this embodiment is also sensorless as in the case of the second embodiment, it is the same as the second embodiment in that the starting sequence for driving the rotor at a predetermined rotation speed or more is required. The method of variable speed control of the rotor of this embodiment requires PWM to be superimposed on the upper and lower transistors of the two arms.
Therefore, in this embodiment, the PWM superimposition selection signal 25 shown in FIG. 1 is set so as to superimpose PWM on the main circuit switching element drive output terminals 3a to 3d.

Example 4. This embodiment shows another example of the connection of the pre-drive circuit 1 in the drive circuit of the brushless motor. FIG. 10 is a configuration diagram of a drive circuit of a single-phase full-wave drive system, and shows a case where a Hall element is used as a magnetic pole sensor of the rotor 53. By using 2d and 2a as the input terminals, the differential output of the Hall element can be taken in as the differential input. 2 for single-phase full-wave drive
An arm is required, turning on / off the transistors 84-87.
The motor coil 98 is controlled to reciprocally energize to rotate the rotor.

The variable speed control method of the rotor requires that the PWM signal be superimposed on either the upper or lower transistor of the two arms. In FIG. 5, the PWM superimposition selection signal 25 of FIG. 1 is set so that the PWM signal is superposed on either 3a, 3c or 3b, 3c. It can be used as a pre-driver for driving a three-phase, two-phase, or single-phase brushless motor. Although not shown, the three-phase half-wave 2
Of course, a half-wave drive type motor can also be driven.

Example 5. In this embodiment, the PWM comparison level signal 21 is changed based on the number of rotations of the motor so that switching noise is not generated. Figure 1
1 is a diagram showing the relationship between the motor rotation speed N, the maximum value of the voltage V applied to the coil, and the electromotive voltage generated in the coil. The electromotive voltage generated in the coil of the brushless motor is expressed as _KE N where the electromotive voltage constant is K _E and the rotation speed is N, and is proportional to the rotation speed N. When the resistance of the coil is R and V-K _E N is ΔV, a current I represented by I = ΔV / R flows in the coil, and thus the current I is the difference between the applied voltage V and the electromotive voltage K _E N. It will be proportional.

Therefore, the programmable logic generator 13 keeps ΔV = V-K _E N constant with respect to the rotation speed N, and further, keeps the current flowing by the constant ΔV below the allowable current. By setting the PWM comparison level signal 21 for generating the applied voltage V, the maximum value V _MAX of the applied voltage and the electromotive voltage K _E N become constant as shown in FIG. The power element can be used below the allowable current of the power element such as the transistor to be driven, and the overcurrent protection does not operate during normal operation such as startup.

In this embodiment, the PWM comparison level signal 21 for generating the applied voltage V is changed so that the overcurrent does not flow in accordance with the rotation speed N of the motor as described above. Does not flow, and it is possible to prevent the switching sound generated when the PWM generated when an overcurrent is periodically turned off. Here, generation of a switching sound when an overcurrent flows will be described. In the PWM control, the power element is periodically turned on and off, but if the frequency is higher than the audible frequency, humans do not perceive it as a sound. However, if an overcurrent is applied, the PWM OFF cycle is audible by the overcurrent protection. If it becomes the following, it will be felt as noise.

Further, the difference between setting the maximum value V _{MAX of the} applied voltage corresponding to the rotation speed N in this embodiment and the case of performing the current I _MAX by the current limitation is that the current is limited in the case of the current limitation. Since it detects and changes the duty of PWM, its PW
When the OFF cycle of M becomes equal to or lower than the audible frequency, the above-mentioned switching sound is generated. However, when detecting the number of revolutions N and controlling the applied voltage V in this embodiment, there is always a time delay in detecting the number of revolutions, so the applied voltage does not reach a voltage equal to or higher than I _MAX.
It is possible to avoid switching sound at an audio frequency due to overcurrent of the WM.

[0058]

As described above, according to the first aspect of the invention, the input terminal portion has three input terminals and input terminals to which signals relating to position information of the brushless motor are supplied to all terminals or some terminals. Is composed of one input terminal to which a comparison signal is supplied to the signal supplied to the output terminal, and the output terminal portion has six output terminals from which signals for driving the brushless motor are output from all terminals or some terminals. The programmable logic generating means generates a signal for driving the brushless motor based on the signal supplied to the input terminal and outputs the signal to the output terminal, so the program of the programmable logic generating means is changed. by doing,
The pattern output to the 6 output terminals can be changed based on the signals from the 4 input terminals, and it is not necessary to develop a new pre-drive circuit with the change of the motor system, and the development period can be shortened. The effect is that the development cost can be reduced. Further, although the input terminal portion and the output terminal portion are fixed, the order thereof can be changed by a program, and jumpers at the time of wiring can be reduced, and the effect of noise can be eliminated.

According to the second aspect of the invention, the programmable logic generating means further selects the PWM control signal for controlling the PWM duty and the superimposition of the PWM signal for each output signal output from the output terminal. The PWM superimposition selection signal is output, and the PWM signal output means outputs P
The PWM signal is output based on the WM control signal, and the PWM superimposing means superimposes the PWM signal on the predetermined output signal output from the output terminal based on the PWM superimposition selection signal. There is an effect that the pattern for superimposing the PWM signal on the output signal can be easily changed and the PWM signal suitable for the type of the motor can be superposed only by changing the program. Also, P
Since the WM signal is superimposed by the PWM signal output means and the PWM superimposing means, the programmable logic generating means can be handled by a small scale, and the size can be reduced.

According to the third aspect of the invention, the programmable logic generating means further outputs, for each output signal output from the output terminal, a positive / negative logic selection signal for selecting the logic, and a positive / negative logic selection signal. Since the logic of the output signal output from the output terminal is changed based on the positive / negative logic selection signal by the negative logic selection means, the logic of the output signal can be easily changed depending on the type of the motor drive circuit. The effect is that the logic of the output signal can be selected according to the type of the motor drive circuit simply by changing the program.

According to the fourth aspect of the invention, the programmable logic generating means further outputs an output state selection signal for selecting the output form of each output signal output from the output terminal, and then selects the output form. As a result, the output form of the output signal output from the output terminal is changed based on the means output state selection signal, so that the logic of the output signal can be easily changed depending on the type of motor drive circuit or the operating state. The effect that the output form of the output signal can be selected according to the type of the motor drive circuit or the operating state by simply changing the program.

According to the fifth invention, a communication terminal is provided, and the programmable logic generating means further comprises:
Since the data is exchanged with the outside through the communication terminal, the individual data of the motor can be read through the communication terminal, and the abnormal data when the motor is used can be read using the data. Can be avoided and also
The communication terminal can also be used to control the pre-drive circuit from the outside.In addition, if a problem occurs during motor operation, the self-diagnosis result of the problem can be recorded and saved externally via the communication terminal. It has the effect of being able to. Further, by inputting data of variations in motor characteristics from the communication terminal, the basic program in the pre-driver can be shared and used regardless of the type of motor.

According to the sixth aspect of the invention, the brushless motor is provided with a current input terminal to which a signal relating to the current flowing through the coil is inputted, and the PWM signal output means further supplies the coil based on the signal inputted from the current input terminal. When an overcurrent is flowing through, the output of the PWM signal is stopped, the output of the PWM signal is further stopped by the programmable logic generating means, and the PWM signal is output from the PWM signal output means after a predetermined time has elapsed. Since the PWM enable set signal is output, the recovery time becomes programmable when the overcurrent detection flows and the PWM signal output is stopped, and the recovery time can be adjusted according to the motor characteristics. It can be used as a current trip function by making the recovery time infinite, and if the recovery time is randomized, it will have a constant frequency. It has the effect that it is possible to reduce switching noise. Further, since the output of the PWM signal is stopped by the PWM signal output means, the programmable logic generating means can be supported by a small-scale device.
This has the effect of enabling miniaturization.

According to the seventh aspect of the invention, the programmable logic generating means further detects the rotation speed of the brushless motor based on the signal supplied to the input terminal, and the rotation speed is N, and the electromotive voltage of the brushless motor is detected. When the constant is K _E , the coil resistance of the brushless motor is R, the applied voltage generated in the coil of the brushless motor based on the PWM signal is V, and the maximum value of the drive current of the brushless motor is I _MAX ,
With respect to the rotation speed N, the PWM control signal is controlled with the maximum value of the PWM duty for generating the applied voltage V with which I _MAX = (V−K _E N) / R becomes a constant value. , The maximum value I of the drive current of the brushless motor at startup
_The drive current does not flow above the _MAX level, and there is the effect that there is no risk of damage to the element due to overcurrent, and there is no irregular switching noise due to overcurrent protection.

According to the eighth aspect of the invention, since the brushless motor predrive circuit is integrated, the versatile brushless motor predrive circuit can be downsized and made easy to handle. Have an effect.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a brushless motor pre-drive circuit according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining outputs of an EXOR circuit 5 and a buffer 4.

FIG. 3 is a circuit diagram showing an example of a configuration of a buffer 4.

FIG. 4 is a circuit diagram showing an example of a hardware configuration for outputting a PWM enable set signal 22.

FIG. 5 is a time chart showing each input / output waveform during the output operation of the PWM enable set signal 22.

FIG. 6 is an explanatory diagram for explaining operation avoidance at a resonance point peculiar to a device equipped with a brushless motor.

FIG. 7 is a configuration diagram of a drive circuit of a three-phase full-wave drive brushless motor when a Hall IC is used as a magnetic pole sensor.

FIG. 8 is a configuration diagram of a drive circuit that detects a magnetic pole position from an electromotive voltage of a motor coil.

FIG. 9 is a configuration diagram of a drive circuit when a two-phase motor is driven without a sensor.

FIG. 10 is a configuration diagram of a drive circuit of a single-phase full-wave drive system.

FIG. 11 is a diagram showing a relationship between a motor rotation speed N, a maximum value of a voltage V applied to a coil, and an electromotive voltage generated in the coil.

[Explanation of symbols]

1 Pre-drive circuit 2 Input terminal (input terminal part) 3 Main circuit switching element drive output terminal (output terminal part) 4 Buffer 5 EXOR circuit (positive / negative logic selection circuit) 6 AND circuit (PWM superposition circuit) 7 OR circuit ( PWM superimposing circuit) 13 programmable logic generator 35 E ² PROM 36 E ² PROM communication terminal (communication terminal)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shirou Tanaka 2-14-40 Ofuna, Kamakura City Mitsubishi Electric Corporation Life Systems Development Laboratory (72) Inventor Yuichi Fukase 2-14-40 Ofuna, Kamakura Mitsubishi Electric Stock Company Life Systems Development Laboratory (72) Inventor Takahiro Hayakawa 3-40 Shimoburo, Tegano, Nakatsugawa City Mitsubishi Electric Engineering Co., Ltd. Nagoya Office Naka Tsukawa Branch

Claims (8)

[Claims] 1. A three input terminal to which signals relating to position information of a brushless motor are supplied to all terminals or a part of terminals, and one input terminal to which a comparison signal to the signal supplied to the input terminals is supplied. Based on the signal supplied to the input terminal section, and the output terminal section composed of six output terminals from which signals for driving the brushless motor are output from all terminals or a part of the terminals. A pre-drive circuit for a brushless motor, comprising: programmable logic generating means for generating a signal for driving the brushless motor and outputting the signal to the output terminal. 2. The programmable logic generating means further includes a PWM control signal for controlling a PWM duty and P for each output signal output from the output terminal.
A PWM signal output means for outputting a PWM superimposition selection signal for selecting superimposition of a WM signal, and a PWM signal output means for outputting the PWM signal based on the PWM control signal; The pre-drive circuit for the brushless motor according to claim 1, further comprising: a PWM superimposing unit that superimposes the PWM signal on a predetermined output signal output from the output terminal. 3. The programmable logic generation means further has a function of outputting a positive / negative logic selection signal for selecting the logic for each output signal output from the output terminal, and the positive logic The pre-drive circuit for a brushless motor according to claim 1 or 2, further comprising positive / negative logic selecting means for changing the logic of the output signal output from the output terminal based on the negative logic selection signal. 4. The programmable logic generating means further has a function of outputting an output state selection signal for selecting an output form of each output signal output from the output terminal, and the output state. The brushless motor pre-drive circuit according to claim 1, further comprising an output form selection unit that changes an output form of the output signal output from the output terminal based on the selection signal. 5. A communication terminal is provided, and the programmable logic generating means further has a function of exchanging data with the outside through the communication terminal. 4. A pre-drive circuit for a brushless motor according to 4. 6. A brushless motor is provided with a current input terminal to which a signal related to a current flowing through the coil is input, and the PWM signal output means further includes an overcurrent to the coil based on the signal input from the current input terminal. Has a function of stopping the output of the PWM signal, and the programmable logic generating means further stops the output of the PWM signal, and after a predetermined time has elapsed, outputs the PWM signal. The brushless motor predrive circuit according to claim 1, 2, 3, 4, or 5, having a function of outputting a PWM enable set signal for outputting a PWM signal from the means. 7. The programmable logic generating means further detects the rotational speed of the brushless motor based on the signal supplied to the input terminal, the rotational speed is N, and the electromotive voltage constant of the brushless motor is K _E. , when the coil resistance of the brushless motor R, the applied voltage generated in the coil of the brushless motor based on the PWM signal V, and the maximum value of the drive current of the brushless motor and I _MAX, the rotational speed N
On the other hand, the PWM control signal is controlled with the maximum value of the PWM duty for generating the applied voltage V at which I _MAX = (V−K _EN ) / R becomes a constant value. The brushless motor pre-drive circuit according to claim 1, 2, 3, 4, 5, or 6. 8. A pre-drive circuit for a brushless motor, characterized in that the pre-drive circuit for the brushless motor according to claim 1, 2, 3, 4, 5, 6 or 7 is integrated into an IC.