JP5954107B2 - Motor control device - Google Patents

Description

  The present invention relates to a brushless motor control device.

  For example, Patent Document 1 describes a motor drive circuit in which the number of output terminals of a phase switching unit that outputs a switching signal for controlling each transistor of an inverter unit is reduced in relation to the position of a rotor of a motor. . Specifically, in the motor drive circuit described in Patent Document 1, in the inverter unit, the switching signal is supplied from the same output terminal to the upper transistor and the lower transistor of the same arm while being supplied. The upper transistor and the lower transistor are configured so as not to be turned on at the same time using the unit and the pre-driver. Thereby, with respect to the three-phase arm of the inverter unit, the number of terminals that output the switching signal from the phase switching unit can be three.

Japanese Patent Laid-Open No. 10-210786

  In the motor drive circuit of Patent Document 1 described above, the number of output terminals from the phase switching unit is three as described above. Furthermore, in this motor drive circuit, one output terminal of the PWM control pulse generator is required for PWM control of the motor. For this reason, for example, when the circuit including the phase switching unit and the PWM control pulse generating unit is integrated, the number of output terminals of the motor control IC is four.

  As described above, the motor drive circuit of Patent Document 1 can reduce the number of output terminals as compared with the prior art, but still needs four output terminals. For this reason, it is difficult for the motor drive circuit of Patent Document 1 to meet the demand for further miniaturization.

  The present invention has been made in view of the above points, and it is possible to further reduce the number of output terminals of a chip incorporating a control signal generation unit that generates a control signal for switching the switching mode of the inverter circuit. An object of the present invention is to provide a simple motor control device.

In order to achieve the above-described object, a motor control device according to the present invention includes:
Detection means (20) for detecting the rotational position of the brushless motor;
Based on the rotational position detected by the detection means, the switching mode of the inverter circuit (50) for driving the brushless motor is determined, and the control is a serial signal representing the switching mode as a digital value of a predetermined number of bits. Control signal generators (32, 36) for generating signals for use;
A clock signal generator (34) for generating a clock signal that serves as a reference for dividing each bit in the control signal when the control signal generator generates the control signal;
A decoder (42) that receives the control signal and the clock signal, and uses the clock signal to decode a digital value representing the switching mode of the inverter circuit from the control signal;
An output unit (44, 46) for outputting a drive signal to the inverter circuit according to a switching mode indicated by the digital value decoded by the decoding unit (42),
The control signal generation unit and the clock signal generation unit are formed in a first chip (10), the decoding unit is formed in a second chip (40), and the first chip and the second chip Are connected via a first signal line (22) for transmitting the control signal and a second signal line (24) for transmitting the clock signal ,
The detection means detects that the rotational position of the brushless motor has changed by the predetermined angle every time the brushless motor rotates by a predetermined angle that requires changing the switching mode of the inverter circuit.
The control signal generation unit transmits the control signal to the second chip in synchronization with the timing at which the detection unit detects that the rotational position of the brushless motor has changed by the predetermined angle. characterized in that it.

  As described above, in the motor control device according to the present invention, the control signal generator determines the switching mode of the inverter circuit, and uses the clock signal generated by the clock signal generator to set the determined switching mode to a predetermined value. A control signal represented by a digital value of the number of bits is generated. The decoding unit receives the control signal and the clock signal, decodes the digital value representing the switching mode from the control signal, and the output unit outputs the drive signal to the inverter circuit according to the switching mode indicated by the digital value. To do.

  Therefore, when the control signal generation unit and the clock signal generation unit are formed on the first chip and the decoding unit is formed on the second chip, the control signal is transmitted between the first chip and the second chip. It is only necessary to connect the first signal line for transmitting and the second signal line for transmitting the clock signal. That is, a signal necessary for switching the switching mode of the inverter circuit can be output only by providing two output terminals on the first chip. Therefore, the number of output terminals can be reduced as compared with the conventional case, and the demand for further miniaturization can be met.

  In the configuration described above, the control signal generator is a serial signal portion that represents the duty ratio of the drive signal as a digital value of a predetermined number of bits in the control signal in order to perform PWM control of the drive signal output to the inverter circuit. The decoding unit decodes the digital value representing the duty ratio of the drive signal from the serial signal portion of the control signal using the clock signal, and the output unit indicates the digital value decoded by the decoding unit A drive pulse signal having a duty ratio may be output to the inverter circuit. As a result, the drive signal output to the inverter circuit can be PWM-controlled without increasing the number of output terminals, and the rotational speed of the motor can be controlled.

  Note that the reference numerals in the parentheses merely show an example of a correspondence relationship with a specific configuration in an embodiment described later in order to facilitate understanding of the present invention, and limit the scope of the present invention. It is not intended.

  Further, the features of the present invention other than the features described above will be apparent from the description of embodiments and the accompanying drawings described later.

It is a block diagram which shows the whole structure of the motor control apparatus by embodiment. It is a figure which shows the correspondence of the output waveform (signal) of Hall sensors A-C, and the switching mode of an inverter circuit. It is a conceptual diagram for showing the positional relationship of the Hall sensor with respect to the brushless motor. FIG. 3 is a functional block diagram functionally showing the configurations of a master drive circuit and a slave drive circuit. It is a flowchart which shows the flow of a process in a master drive circuit. It is a flowchart which shows the flow of a process in a slave drive circuit. It is explanatory drawing for demonstrating operation | movement of a master drive circuit and a slave drive circuit. It is a wave form diagram which shows an example of the PWM output as a drive signal output to each switching element of an inverter circuit, and the terminal voltage of each stator winding (U phase, V phase, W phase) of a motor. It is a flowchart which shows the flow of a process in the master drive circuit in 2nd Embodiment. It is a figure for demonstrating the effect acquired by the process shown to the flowchart of FIG. It is the block diagram which showed the structure of the modification.

(First embodiment)
Hereinafter, a motor control device according to a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of the motor control apparatus according to the present embodiment. The motor 60 to be controlled by the motor control apparatus 100 according to the present embodiment is a brushless motor having a three-phase (U-phase, V-phase, W-phase) stator winding and a rotor made of permanent magnets. .

  In FIG. 1, the motor 60 is connected to a power source and a ground via an inverter circuit 50. The inverter circuit 50 is composed of six switching elements (for example, power MOSFETs and IGBTs) that form a pair corresponding to the U phase, V phase, and W phase of the motor 60. That is, in the inverter circuit 50, a pair of high-potential side and low-potential side switching elements are provided for each phase of the motor 60, and a connection line between the high-potential side and low-potential side switching elements is It is connected to each phase of the motor 60. A protection diode is connected in parallel to each switching element.

  Accordingly, by appropriately switching the on / off combination (hereinafter referred to as switching mode) of each switching element of the inverter circuit 50, the energization pattern to the motor 60 is changed, and the rotor is rotated by the stator winding. The magnetic field can be generated.

  A drive signal for driving each switching element of the inverter circuit 50 described above in an appropriate switching mode is output from a slave drive circuit 40 formed in the driver IC chip. The slave drive circuit 40 generates the drive signal described above based on the control signal and the clock signal supplied from the master drive circuit 30 formed in the motor control microcomputer chip 10 and outputs the drive signal to the inverter circuit 50.

  In the present embodiment, as shown in FIG. 1, the master drive circuit 30 and the slave drive circuit 40 have a first signal line 22 for transmitting a control signal and a second signal line for transmitting a clock signal. The signal line 24 is only connected via the two signal lines 22 and 24. For this reason, in this embodiment, a signal required for switching the switching mode of the inverter circuit 50 can be output only by providing the motor control microcomputer chip 10 with two output terminals. Therefore, the number of output terminals can be reduced as compared with the conventional case, and the demand for further miniaturization can be met.

  Hereinafter, the reason why the master drive circuit 30 and the slave drive circuit 40 can be connected by the two signal lines 22 and 24 will be clarified by describing them in detail.

  The master drive circuit 30 is formed in the motor control microcomputer chip 10. The master drive circuit 30 acquires the target rotational speed of the motor 60 from other circuits in the motor control microcomputer chip 10. Further, the master drive circuit 30 inputs detection signals from Hall sensors A to C as the rotational position detection means 20.

  Here, the Hall sensors A to C detect the magnetic poles N and S of the rotor, and as shown in FIG. 2, while the electrical angle of the rotor changes by 360 degrees, each of the Hall sensors A to C is at a high level in an angular range of 180 degrees. In the remaining 180 degree angle range, a low level signal is output. In the case of a three-phase, two-pole, three-slot brushless motor, each Hall sensor A to C is arranged between each stator winding and perpendicular to the rotation axis as shown in FIG. Yes. For this reason, the phases of the signals output from the hall sensors A to C are shifted by 120 degrees as shown in FIG. Therefore, as shown in FIG. 2, the master drive circuit 30 detects that the electrical angle of the rotor has changed by 60 degrees based on the timing at which the level of the output signal of any of the hall sensors A to C changes. Can do.

  As shown in FIG. 4, the master drive circuit 30 has a duty / mode calculation unit 32. When it is detected that the electrical angle of the rotor has changed by 60 degrees next time, the duty / mode calculation unit 32 outputs a Hall sensor signal generated for the rotational position of the rotor at that time to the inverter circuit 50. Is stored as a signal indicating the switching mode (see FIG. 2).

  Here, the switching mode of the inverter circuit 50 will be described. For example, when the 120-degree energization method is adopted, every time the electrical angle of the rotor changes by 60 degrees, U phase → V phase, U phase → W phase, V phase → W phase, V phase → U phase, It is necessary to energize so as to change the current direction (magnetic field direction) of the stator winding, such as W phase → U phase and W phase → V phase. In this case, six energization patterns are required to rotate the rotor. Therefore, the number of switching modes of the inverter circuit 50 necessary for switching the energization pattern is also six, and as shown in FIG. 2, six switching modes are associated with six types of hall sensor signals. For this reason, the Hall sensor signal can be used as a signal indicating the switching mode.

  When stopping energization of the motor 60, generally, all the high-potential side switching elements may be turned off or all the low-potential side switching elements may be turned off. In either switching mode, since no current is passed through the motor 60, the stator winding of the motor 60 does not generate a magnetic field for rotating the rotor. As described above, there are generally two non-energization patterns in which no current is supplied to the motor 60. Therefore, in consideration of this non-energization pattern, the total number of switching modes of the inverter circuit 50 is eight.

  Thus, the number of switching modes of the inverter circuit 50 in the 120-degree energization method is generally 8, and can be represented by a 3-bit digital value. Therefore, for example, switching modes corresponding to two non-energization patterns are represented by “000” and “111”, and switching modes corresponding to other energization patterns are represented by Hall sensor signals “001” to “001” as shown in FIG. The correspondence between the switching mode and the 3-bit digital value, such as “110”, is determined and stored in advance.

  Further, the duty / mode calculation unit 32 calculates the actual rotation speed of the rotor based on the 60-degree phase change detection signals from the hall sensors A to C. Then, in accordance with the difference from the target rotational speed acquired from other circuits in the motor control microcomputer chip 10, the driving for driving the switching element of the inverter circuit 50 using, for example, PI control or the like so as to reduce the difference. Calculate the duty ratio of the signal.

  Then, the duty / mode calculation unit 32 determines a digital value corresponding to the calculated duty value so that the duty ratio is also expressed as a digital value. For example, consider a case in which the range of the duty ratio is 0 to 100% and the range is divided and represented by a 5-bit digital value. The number of divisions that can be counted by a 5-bit digital value is 32. Therefore, the duty ratio range of 0 to 100% is equally divided into 32 sections. When the duty ratio of the drive signal is calculated, the duty / mode calculation unit 32 determines which of the 32 divided sections the duty ratio belongs to, and calculates a digital value corresponding to the belonging section. .

  Note that when the resolution of the duty ratio requires a more detailed division, the number of bits of the digital value indicating the duty ratio may be increased. On the other hand, if the rough division is sufficient, the number of bits of the digital value may be reduced. Further, when the motor 60 has only to be rotated at a constant speed, the duty / mode calculating unit 32 does not have to calculate the duty ratio.

  The drive enable signal shown in FIG. 4 is output from another circuit in the motor control microcomputer chip 10, and is turned on when the motor 60 is to be started and turned off when the motor 60 is to be stopped. When the drive enable signal is turned off, the duty / mode calculation unit 32 stops operating.

  As described above, the duty / mode calculation unit 32 calculates the digital value indicating the switching mode of the inverter circuit 50 (for example, using the 3 bits of the Hall sensor signal as it is) and the digital value indicating the duty ratio of the drive signal. To do. When a 60 degree phase change is detected by the 60 degree phase change detection signals from the hall sensors A to C, a communication start bit indicating the start of communication, a digital value indicating the duty ratio, and a digital indicating the switching mode The control signal including the value is output to the subsequent parallel-serial conversion unit 36. That is, the duty / mode calculation unit 32 transmits a control signal to the slave drive circuit 40 every time the electrical angle of the rotor changes by 60 degrees.

  The parallel-serial conversion unit 36 performs parallel-serial conversion on the control signal output from the duty / mode calculation unit 32 with reference to the clock signal output from the clock signal generation unit 34. That is, the parallel-serial conversion unit 36 converts each bit of the digital value included in the control signal output from the duty / mode calculation unit 32 into a conversion target in a predetermined order. When the bit data of the digital value to be converted is 1, the serial signal has a level corresponding to 1, and when the bit data of the digital value is zero, the serial signal corresponds to zero. Level. Each time a clock signal is input, the bits of the digital value to be converted are updated. As a result, the parallel-serial conversion unit 36 generates a serial signal that is divided for each bit of the digital value included in the control signal on the basis of the clock signal and whose level changes according to the data of each bit. Can do. The serial signal (control signal) generated by the parallel / serial conversion unit 36 is transmitted to the slave drive circuit 40 via the first signal line 22.

  The duty / mode calculation unit 32 and the parallel / serial conversion unit 36 described above correspond to the control signal generation unit of the present invention.

  The clock signal generation unit 34 divides (or multiplies) the internal clock of the motor control microcomputer as necessary to generate a clock signal to be supplied to the parallel-serial conversion unit 36. This clock signal is also transmitted to the slave drive circuit 40 via the second signal line 24.

  Next, the slave drive circuit 40 will be described. As shown in FIG. 4, the slave drive circuit 40 includes a serial / parallel conversion unit 42 corresponding to the decoding unit of the present invention. The serial / parallel converter 42 receives a control signal and a clock signal that are converted into a serial signal. The serial / parallel conversion unit 42 decodes each bit of the digital value included in the control signal converted into a serial signal with reference to the input clock signal. That is, every time a clock signal is input, the serial / parallel converter 42 converts the serial signal into a digital value according to the level of the serial signal, and outputs the digital value to the PWM control pulse generator 44.

  The PWM control pulse generator 44 is based on the control signal converted into a digital value by the serial / parallel converter 42 and the clock signal generated by the clock signal generator 34 of the master drive circuit 30. A drive signal is generated and output. Specifically, since a communication start bit is set at the head of the control signal, the PWM control pulse generator 44 uses the communication start bit to generate a digital value representing the duty ratio and a digital representing the switching mode. It is possible to recognize the value. Then, the switching mode of the inverter circuit 50 is determined on the basis of the digital value representing the switching mode and the correspondence relationship between the switching mode and the digital value that are determined and stored in advance (see FIG. 2). Further, a switching element that outputs a drive signal is determined according to the determined switching mode. At this time, the drive signal is a PWM control pulse signal having a duty ratio corresponding to the digital value based on a digital value representing the duty ratio included in the control signal. A method for generating the PWM control pulse signal will be described later.

  The PWM control pulse signal as the drive signal generated by the PWM control pulse generator 44 is amplified by the pre-driver 46 and output to the inverter circuit 50. Therefore, the PWM control pulse generator 44 and the pre-driver 46 correspond to the output unit of the present invention.

  As described above, in the present embodiment, in the master drive circuit 30, the control signal including the digital value indicating the switching mode of the inverter circuit 50 and the digital value indicating the duty ratio of the drive signal is serialized using the clock signal. Convert to signal. Then, the slave drive circuit 40 decodes the digital value representing the switching mode and the digital value representing the duty ratio from the serial signal using the clock signal. Therefore, the master drive circuit 30 simply sends the control signal converted into a serial signal and the clock signal used as a reference for the serial signal to the slave drive circuit 40, and the slave drive circuit 40 transmits the drive signal. Information necessary for generation can be acquired. For this reason, the master drive circuit 30 and the slave drive circuit 40 need only be connected by the two signal lines 22 and 24.

  Next, the flow of processing in the master drive circuit 30 and the slave drive circuit 40 will be described using the flowcharts of FIGS. 5 and 6 with reference to the operation explanatory diagram shown in FIG.

  First, the flow of processing in the master drive circuit 30 will be described with reference to the flowchart of FIG. In step S100, at the start of drive control of the motor 60, for example, a control signal indicating a predetermined duty ratio is transmitted in a switching mode corresponding to the stored rotor position. In step S110, based on the signals from the hall sensors A to C, it is determined whether the rotor has started to rotate and a phase change of 60 electrical angles has been detected. Note that the rotor position when the phase change of 60 electrical angles is detected is stored in a memory (not shown) of the master drive circuit 30. Furthermore, measurement of the time from the rotor position until the next phase change at an electrical angle of 60 degrees is detected is started using an internal timer.

  If it is determined that a phase change of 60 electrical angles has been detected, the process proceeds to step S120, and a control signal is transmitted. That is, as shown in FIG. 7, the master drive circuit 30 starts transmission of a control signal triggered by the detection of a phase change of 60 electrical angles. The control signal includes a communication start bit, a bit representing a duty ratio, and a bit representing a switching mode, for example, as shown in FIG. The clock signal is always transmitted from the master drive circuit 30 to the slave drive circuit 40 after the motor drive control is started, irrespective of the transmission of the control signal.

  In the subsequent step S130, a control signal to be transmitted when the phase change of the electrical angle of 60 degrees is detected next time is generated and stored. Specifically, for example, the actual rotation speed of the rotor is calculated from the elapsed time during which the past two phase changes of the electrical angle of 60 degrees are detected, and the duty ratio is calculated based on the difference from the target rotation speed. The digital value corresponding to the duty ratio is calculated. Further, based on the rotational position of the rotor when the phase change of 60 electrical degrees is detected, the Hall sensor signal corresponding to the switching mode to be switched next time the phase change of 60 electrical angles is detected. Calculated and set to a digital value representing the switching mode. Then, the control signal is generated by using the digital value corresponding to the duty ratio and the digital value representing the switching mode. Thus, since the control signal is prepared in advance, transmission of the control signal can be started in synchronization with the detection of the phase change of the electrical angle of 60 degrees, which is a transmission trigger.

  In a succeeding step S140, it is determined whether or not the motor 60 is instructed to stop based on whether or not the drive enable signal is turned off. When the stop of the motor 60 is instructed, the process shown in the flowchart of FIG. On the other hand, when the stop of the motor 60 is not instructed, the processing from step S110 is repeated.

  Next, the flow of processing in the slave drive circuit 40 will be described with reference to the flowchart of FIG. In step S200, it is determined whether communication of a control signal from the master drive circuit 30 is started based on whether a communication start bit is detected. If it is determined that the communication is started, the process proceeds to step S210 to receive a control signal, and in step S220, the received control signal is sequentially converted into a digital value. Further, the converted digital values are collected for each data type, and the digital value representing the duty ratio and the digital value representing the switching mode are decoded.

  In the subsequent step S230, the switching mode and the duty ratio are updated based on the decoded digital values, for example, at the start of the PWM cycle. By switching the switching mode, it is switched to which switching element the drive signal is output from the slave drive circuit 40.

  Here, a method for generating a PWM control pulse signal corresponding to the updated duty ratio as a drive signal will be described with reference to FIG.

  First, a triangular wave carrier signal is generated using a clock signal. For example, the counter increments the count value every time a clock signal is input from the initial value of zero, thereby making the count value a pseudo triangular wave carrier signal. Note that the counter uses the number of divisions that can be counted based on the number of bits of the digital value for representing the duty ratio as the upper limit of the count value, and starts counting from zero when the count value reaches the upper limit. The period required for counting from the initial value zero to the number of divisions that can be counted by the number of bits of the digital value for representing the duty ratio is the PWM cycle as shown in FIG.

  As described above, the switching mode and the duty ratio are updated at the start of the PWM cycle, as shown in FIG. In the example shown in FIG. 7, the digital value indicating the duty ratio before update is “10110”, but it has been changed to “01111” by the update. The switching mode is updated from “000110” (Hall sensor signal “001”) to “100100” (Hall sensor signal “101”).

  Then, the count value by the counter is compared with the digital value representing the updated duty ratio, and the period during which the digital value representing the duty ratio is equal to or greater than the count value of the counter is on, and the period is smaller than the counter value Generates a pulse signal that turns off. As a result, a PWM control pulse signal that is turned on / off at the duty ratio represented by the digital value can be generated. The PWM control pulse signal generated in this way is output as a drive signal to the switching element of the inverter circuit 50 to which the drive signal should be output in the updated switching mode.

  In step S240, it is determined whether or not the stop of the motor 60 is instructed based on whether or not the transmission of the signal from the master drive circuit 30 is stopped. If the stop is instructed, the flowchart shown in FIG. The process ends.

  FIG. 8 shows an example of a PWM output as a drive signal output to each switching element of the inverter circuit 50 by executing the processing as described above. As shown in FIG. 8, the switching mode is updated every time the rotor changes phase by 60 degrees in electrical angle. In addition, when the switching mode is updated, the duty ratio of the PWM signal as the drive signal is also updated.

  7 and 8 show an example in which an upper phase PWM method for outputting a PWM signal to the switching element on the high potential side is employed. However, other methods may be adopted as the PWM method.

  In the example shown in FIG. 8, the terminal voltage of each stator winding (U phase, V phase, W phase) of the motor 60 is also shown. As shown in FIG. 8, each terminal voltage gradually increases before the corresponding high-potential side switching element is PWM driven, and gradually decreases after the PWM driving is completed. . This is because both the high-potential side and low-potential side switching elements are turned off, so that the voltage of the phase causes the residual voltage of the stator winding and the induced voltage generated by the permanent magnet of the rotating rotor. This is because it gradually changes due to the cooperative action.

(Second Embodiment)
Next, a motor control device according to a second embodiment of the present invention will be described. However, the motor control device according to the present embodiment is structurally similar to that of the first embodiment, and only the control process in the master drive circuit 30 is partially different. Therefore, description regarding the configuration is omitted, and only control processing in the master drive circuit 30 will be described.

  In the first embodiment described above, the master drive circuit 30 transmits a control signal using the detection of a phase change at an electrical angle of 60 degrees as a trigger. For this reason, as shown in FIG. 7, in the motor control device of the first embodiment, the switching mode of the inverter circuit 50 and the duty ratio of the PWM control pulse signal are changed from the time point when the phase change of the electrical angle of 60 degrees is detected. This is not possible, and is delayed by at least the transmission of the control signal. Since the delay due to the transmission of the control signal is a short time, the influence on the motor control is almost negligible. However, in order to execute the motor control more precisely, it is preferable that the switching mode and the duty ratio are updated in synchronization with the detection timing of the phase change at the electrical angle of 60 degrees.

  Therefore, in this embodiment, the next timing when the phase change of the electrical angle of 60 degrees is detected is predicted from the actual rotational speed of the rotor, and the transmission of the control signal is completed by the predicted timing. It is.

  The flowchart of FIG. 9 shows the control flow of the master drive circuit 30 in the present embodiment. In steps S300 and S310, processing similar to that in steps S100 and S110 in the flowchart of FIG. 5 is performed.

  In step S320, the next timing of detecting a phase change of 60 electrical degrees is predicted from the actual rotational speed of the rotor. For example, when the actual rotational speed is maintained, a timing at which a phase change of 60 electrical angles will be detected is calculated. Alternatively, the rotational acceleration may be calculated from the actual rotational speed, and the phase change detection timing at an electrical angle of 60 degrees may be calculated when the actual rotational speed is changed by the rotational acceleration.

  In the subsequent step S330, the transmission is performed so that the transmission of the control signal is completed by the prediction timing in consideration of the time necessary for transmitting the control signal with the prediction timing calculated in step S320 as a reference. Determine the start timing. In step S340, it is determined whether or not the transmission timing has been reached. If it is determined that the transmission timing has been reached, transmission of a control signal is started in step S350.

  Note that the processing in steps S360 and S370 is the same as the processing in steps S130 and S140 in the flowchart of FIG.

  By executing such processing, as shown in FIG. 10, transmission of the control signal to the slave drive circuit 40 can be completed before the phase change detection timing of 60 electrical degrees. Therefore, in the slave drive circuit 40, it is possible to update the switching mode and the duty ratio at a time closer to the phase change detection timing of the electrical angle of 60 degrees compared to the case of the first embodiment.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. .

  For example, in the above-described embodiment, an example in which the serial / parallel conversion unit 42 as the decoding unit, the PWM control pulse generation unit 44 and the pre-driver 46 as the output unit are formed in the driver IC chip as the second chip. explained. However, these are not necessarily formed in one chip. For example, as shown in FIG. 11, a chip that forms the serial-parallel converter 42 and a chip that forms the PWM control pulse generator 44 and the pre-driver 46 are formed. May be divided. Further, the PWM control pulse generator 44 and the pre-driver 46 may be formed on separate chips. This is because in any case, the number of output terminals of the motor control microcomputer chip 10 can be reduced.

  In the above-described embodiment, an example in which the 120-degree energization method is employed as the motor drive method has been described. However, other drive methods such as a 180-degree energization method may be employed. Furthermore, in the above-described embodiment, the hall sensor is adopted as the means for detecting the rotational position of the motor, but other detection means such as a photo interrupter may be used. Alternatively, the sensorless method may be adopted, and the rotational position of the rotor may be calculated from the induced voltage of the empty three-phase winding.

DESCRIPTION OF SYMBOLS 10 Motor control microcomputer 20 Rotation position detection means 30 Master drive circuit 32 Duty / mode calculation part 34 Clock signal generation part 36 Parallel serial conversion part 40 Slave drive circuit 42 Serial parallel conversion part 44 PWM control pulse generation part 50 Inverter circuit 60 Motor

Claims (5)

Detection means (20) for detecting the rotational position of the brushless motor;
Based on the rotational position detected by the detection means, the switching mode of the inverter circuit (50) for driving the brushless motor is determined, and the control is a serial signal representing the switching mode as a digital value of a predetermined number of bits. Control signal generators (32, 36) for generating signals for use;
A clock signal generator (34) for generating a clock signal that serves as a reference for dividing each bit in the control signal when the control signal generator generates the control signal;
A decoder (42) that receives the control signal and the clock signal, and uses the clock signal to decode a digital value representing the switching mode of the inverter circuit from the control signal;
An output unit (44, 46) for outputting a drive signal to the inverter circuit according to a switching mode indicated by the digital value decoded by the decoding unit;
The control signal generation unit and the clock signal generation unit are formed in a first chip (10), the decoding unit is formed in a second chip (40), and the first chip and the second chip Are connected via a first signal line (22) for transmitting the control signal and a second signal line (24) for transmitting the clock signal ,
The detection means detects that the rotational position of the brushless motor has changed by the predetermined angle every time the brushless motor rotates by a predetermined angle that requires changing the switching mode of the inverter circuit.
The control signal generation unit transmits the control signal to the second chip in synchronization with the timing at which the detection unit detects that the rotational position of the brushless motor has changed by the predetermined angle. A motor control device. Detection means (20) for detecting the rotational position of the brushless motor;
Based on the rotational position detected by the detection means, the switching mode of the inverter circuit (50) for driving the brushless motor is determined, and the control is a serial signal representing the switching mode as a digital value of a predetermined number of bits. Control signal generators (32, 36) for generating signals for use;
A clock signal generator (34) for generating a clock signal that serves as a reference for dividing each bit in the control signal when the control signal generator generates the control signal;
A decoder (42) that receives the control signal and the clock signal, and uses the clock signal to decode a digital value representing the switching mode of the inverter circuit from the control signal;
An output unit (44, 46) for outputting a drive signal to the inverter circuit according to a switching mode indicated by the digital value decoded by the decoding unit;
The control signal generation unit and the clock signal generation unit are formed in a first chip (10), the decoding unit is formed in a second chip (40), and the first chip and the second chip Are connected via a first signal line (22) for transmitting the control signal and a second signal line (24) for transmitting the clock signal,
The detection means detects that the rotational position of the brushless motor has changed by the predetermined angle every time the brushless motor rotates by a predetermined angle that requires changing the switching mode of the inverter circuit.
The first chip includes prediction means (32, S320) for predicting a timing at which the detection means detects that the rotational position of the brushless motor changes by the predetermined angle ,
It said control signal generating unit, the so transmission of the control signal until the timing predicted by predicting means is completed, and features that you transmitted to the control signal to the second chip Motor control device. The control signal generation unit also includes a serial signal portion representing a duty ratio of the drive signal as a digital value of a predetermined number of bits in the control signal in order to perform PWM control of the drive signal output to the inverter circuit. Include
The decoding unit decodes a digital value representing a duty ratio of the drive signal from the serial signal portion of the control signal using the clock signal,
The output unit, the motor control device according to claim 1 or 2, characterized in that for outputting a driving pulse signal having a duty ratio that indicates a digital value decoded by said decoding unit to the inverter circuit. The digital value of the predetermined number of bits representing the duty ratio of the drive signal is obtained by dividing the duty ratio by the number of divisions that can be counted by the number of bits of the digital value.
4. The motor according to claim 3 , wherein the output unit outputs a drive pulse signal having the duty ratio with a ratio of the number of divisions indicated by the digital value to the total number of divisions that can be counted as a duty ratio. Control device. The control signal generation unit calculates a duty ratio of the drive signal according to a difference between a target rotation speed and an actual rotation speed when the brushless motor rotates by a predetermined angle.
In response to detecting that the rotational position of the brushless motor has changed by a predetermined angle, a duty ratio for a control signal transmitted in response to the next angle change detection timing is calculated in advance. The motor control device according to claim 1 , wherein the motor control device is a motor control device.

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