JPH09117185A - Real time output circuit for dc brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a real time output circuit for DC brushless motor respond at a high speed without being affected by interruption processing holding time, software processing time of a CPU, etc., by incorporating a selection circuit for selecting an external interruption signal as a transfer trigger in addition to the output signal of a timer in the output circuit. SOLUTION: A real time output circuit is constituted so that the circuit can transfer the content of a slave buffer register 9, namely, the OFF pattern of an PWM to an output latch 12 when an external interruption signal 14 is supplied to the register 9 or the content of another slave buffer register 22, namely, a fail-safe output pattern to the output latch 12 when another external interrupt signal 15 is supplied to the resistor 22. The hardware of the output circuit can be constituted so that a fail-safe output can be made by means of the interrupt signal 15 when the output of the PWM is turned off by using the interrupt signal 14. Therefore, the speed of response of the output circuit can be increased regardless of the speed of response to interruption and processing speed of the output circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a real-time output circuit for a DC brushless motor, and more particularly to a real-time output circuit for a DC brushless motor in an inverter waveform generation circuit for controlling a DC brushless motor which is composed of a single chip microcomputer.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing the structure of a DC brushless motor.

Referring to FIG. 2, the DC brushless motor includes an AC / DC converter 24 for converting an AC power supply into a DC power supply, and a voltage / current detection circuit 26 for extracting a voltage signal and a current signal from the DC power supply. An inverter waveform generation circuit 29 that generates an inverter waveform, a driver 30 that drives the DC motor 32, and a rotor position detection circuit 33 that detects the rotational position of the rotor of the DC motor 32.
Is included as a main configuration.

Here, a signal level shifter 34 is required to drive the driver 30, and a dedicated photocoupler or the like is used to drive the driver 30. In addition, DC / DC is used for the inverter waveform generation circuit 29 and each photocoupler.
Power is supplied by the converter 35.

The AC / DC converter 24 is a harmonic rectifier circuit composed of a diode bridge, a capacitor, a coil and the like.

The voltage / current detection circuit 26 outputs, as a signal, a voltage that is divided by a resistance and a voltage that appears in a current transformer or a power resistance. Also, the fact that the voltage level exceeds a predetermined voltage level is detected by a comparator or the like and output as an abnormal signal.

The inverter waveform generation circuit 29 is composed of a single-chip microcomputer for controlling the inverter as described later.

The rotor position detecting circuit 33 uses a method of directly detecting the position of the rotor by a position detecting element such as a photo interrupter or a rotation of the rotor which is a permanent magnet in a coil not driven by a motor driver. A method is used in which the electromotive force generated is separated by a resistance voltage divider or a comparator to detect the position.

Next, the operation of the DC brushless motor will be described with reference to FIG.

An AC / DC converter 24 converts an AC100V power supply 23 into a DC200V power supply 25. The voltage / current detection circuit 26 transmits the power supply voltage and the power supply current to the inverter waveform generation circuit 29 as a voltage signal 27 and a current signal 28, respectively. The driver 30 uses the inverter signal 31 from the inverter waveform generation circuit 29 to drive D
The DC motor 3 is switched by switching the power source 25 of C200V.
2 is driven. The rotor position detection circuit 33 detects the rotational position of the rotor of the DC motor 32 and feeds it back to the inverter waveform generation circuit 29.

FIG. 3 is a circuit diagram of a driver for a three-phase DC motor. As shown in FIG. 3, the three-phase DC motor driver is composed of six transistors 41, 42 ,.

FIG. 4 is a timing chart of inverter signals applied to the driver for the three-phase DC motor shown in FIG. As shown in FIG. 4, the inverter signal 31 generated by the inverter waveform generation circuit 29 has a waveform of which one cycle has 6 patterns.

FIG. 5 is a simplified vector diagram showing the line current in the DC motor and the direction of the magnetic field generated in the coil in the DC motor by this current. In FIG. 5, one cycle is represented as one rotation.

As shown in FIG. 5, depending on the position of the rotor, D
Since the direction of the current flowing in the C motor 32 is controlled in six ways, the inverter signal 31 is divided into patterns of which one cycle has six ways as shown in FIG. Then, in order to control the current flowing in the DC motor 32 according to the torque required for rotation, each pattern has one of the six inverter signals.
Books are PWM (pulse width modulation)
It has a waveform.

The driving principle of the DC motor 32 will be described below with reference to FIGS.

The wirings 36 and 37 labeled "P" and "N" in the circuit diagram of the driver 30 shown in FIG.
It is connected to a 0 V DC power supply 25. On the other hand, the wirings 38, 39, and 40 marked with “U”, “V”, and “W” in the circuit diagram of the driver 30 shown in FIG.
2 is connected.

The operation when the six inverter signal patterns 53, 54, 55, 56, 57 and 58 shown in FIG. 4 are applied to the driver 30 will be described below in order.

In the inverter signal pattern 53 shown in FIG. 4, the inverter signal (UP) 47 is active, whereby the transistor 41 of FIG. 3 is turned on and a voltage of 200 V is generated on the wiring (U) 38. On the other hand, the inverter signal (VN) 51 has a PWM waveform in which active and inactive are repeated, which causes the transistor 4
5 is repeatedly turned on and off, and 0 V and high impedance are repeatedly generated in the wiring (V) 39.

Therefore, the wiring (U) 3 is connected to the DC motor 32.
A current controlled by PWM flows between the wiring 8 and the wiring (V) 39. This relationship is indicated by arrow 53 in FIG. here,
Inverter signal (VP) 48, (WP) 49, (UN)
Since 50 and (WN) 52 are not active, the transistors 42, 43, 44 and 46 have high impedance.

In the inverter signal pattern 54 shown in FIG. 4, the inverter signal (UP) 47 is active,
This is a PWM waveform in which the inactive state is repeated. As a result, the transistor 41 of FIG. 3 is repeatedly turned on and off, and 200 V, high impedance is repeatedly generated in the wiring (U) 38. On the other hand, the inverter signal (WN) 52 is active, so that the transistor 46 is turned on and a voltage of 0 V is generated on the wiring (W) 40.

Therefore, the wiring (U) 3 is connected to the DC motor 32.
A current controlled by PWM flows between the wiring 8 and the wiring (W) 40. This relationship is indicated by arrow 54 in FIG. here,
Inverter signal (VP) 48, (WP) 49, (UN)
Since 50 and (VN) 51 are not active, the transistors 42, 43, 44 and 45 have high impedance.

In the inverter signal pattern 55 shown in FIG. 4, the inverter signal (VP) 48 is active, whereby the transistor 42 of FIG. 3 is turned on and a voltage of 200 V is generated on the wiring (V) 39. On the other hand, the inverter signal (WN) 52 has a PWM waveform that repeats active and inactive states.
6 is repeatedly turned on and off, and 0 V and high impedance are repeatedly generated in the wiring (W) 40.

Therefore, the wiring (V) 3 is connected to the DC motor 32.
A current controlled by PWM flows between the wiring 9 and the wiring (W) 40. This relationship is indicated by arrow 55 in FIG. here,
Inverter signal (UP) 47, (WP) 49, (UN)
Since 50 and (VN) 51 are not active, the transistors 41, 43, 44 and 45 have high impedance.

In the inverter signal pattern 56 shown in FIG. 4, the inverter signal (VP) 48 is active,
This is a PWM waveform in which the inactive state is repeated. As a result, the transistor 42 in FIG. 3 is repeatedly turned on and off, and the wiring (V) 39 is repeatedly caused to have 200 V and high impedance. On the other hand, the inverter signal (UN) 50 is active, so that the transistor 44 is turned on and a voltage of 0 V is generated on the wiring (U) 38.

Therefore, the wiring (V) 3 is connected to the DC motor 32.
A current controlled by PWM flows between the wiring 9 and the wiring (U) 38. This relationship is indicated by arrow 56 in FIG. here,
Inverter signal (UP) 47, (WP) 49, (VN)
Since 51 and (WN) 52 are not active, the transistors 41, 43, 45 and 46 have high impedance.

In the inverter signal pattern 57 shown in FIG. 4, the inverter signal (WP) 49 is active, which turns on the transistor 43 in FIG. 3 to generate a voltage of 200 V on the wiring (W) 40. On the other hand, the inverter signal (UN) 50 has a PWM waveform that repeats active and inactive states.
4 is repeatedly turned on and off, and 0 V and high impedance are repeatedly generated in the wiring (U) 38.

Therefore, the wiring (W) 4 is applied to the DC motor 32.
A current controlled by PWM flows between 0 and the wiring (U) 38. This relationship is indicated by arrow 57 in FIG. here,
Inverter signal (UP) 47, (VP) 48, (VN)
Since 51 and (WN) 52 are not active, the transistors 41, 42, 45 and 46 have high impedance.

In the inverter signal pattern 58 shown in FIG. 4, the inverter signal (WP) 49 is active,
This is a PWM waveform in which the inactive state is repeated, whereby the transistor 43 in FIG. 3 is repeatedly turned on and off, and 200 V, high impedance is repeatedly generated in the wiring (W) 40. On the other hand, the inverter signal (VN) 51 is active, whereby the transistor 45 is turned on and a voltage of 0 V is generated on the wiring (V) 39.

Therefore, the wiring (W) 4 is applied to the DC motor 32.
A current controlled by PWM flows between 0 and the wiring (V) 39. This relationship is indicated by arrow 58 in FIG. here,
Inverter signal (UP) 47, (VP) 48, (UN)
Since 50 and (WN) 52 are not active, the transistors 41, 42, 44 and 46 have high impedance.

As described above, by adding the inverter signal as shown in FIG. 4 to the driver for the three-phase DC motor shown in FIG. 3, the rotating current ( A rotating magnetic field) can be obtained.

FIG. 6 is a block diagram of a conventional real-time output circuit for a DC brushless motor. As shown in FIG. 6, an inverter waveform generation circuit that generates a waveform in which one of the six inverter signals is used as a PWM output can be realized by using, for example, a conventional inverter microcomputer (μPD78362A).

Referring to FIG. 6, the timer counter 1 counts the clock and counts up from 0 to the value set in the compare register 10. The compare register 3 is set to 0 in advance.

First, the slave buffer register 7 is triggered by a match signal between the timer counter 1 and the compare register 3.
Is transferred to the output latch 12. Bit patterns corresponding to six inverter signals when PWM is active (also referred to as “ON”) are set in the slave buffer register 7 in advance. For example, the inverter signal (UP) 4 in the inverter signal pattern 55 of FIG.
7, (VP) 48, (WP) 49, (UN) 50, (V
N) 51 and (WN) 52 are replaced by bit5 and bit, respectively.
If it is assigned to 4, bit3, bit2, bit1, and bit0, the bit pattern becomes "010001".

Next, the slave buffer register 9 is triggered by a match signal between the timer counter 1 and the compare register 5.
Is transferred to the output latch 12. PWM is inactive in advance in the slave buffer register 9 (“OF
(Also referred to as “F”), bit patterns corresponding to the six inverter signals are set. For example, in the case of the inverter signal pattern 55 of FIG. 4, the bit pattern is "0.
It becomes 10,000 ".

FIG. 7 shows the inverter signal pattern 55 of FIG.
3 is a timing chart for explaining the PWM output in FIG.

As shown in FIG. 7, the PWM output has its cycle determined by the value set in the compare register 10, and its ON time is determined by the value set in the compare register 5.

Here, in order to switch the pattern every 1/6 cycle, a bit pattern corresponding to the inverter signal of the next pattern is set in the master buffer registers 6 and 8.

That is, when the compare register and the slave buffer register are configured as a double buffer and the values are set in the corresponding buffer register and master buffer register, respectively, the set value is changed at the same timing as the value of the compare register 10. Transfers are made from the master buffer register to the slave buffer register, and so on.

In the conventional DC brushless motor real-time output circuit, interrupt processing can be started at the timing matching the value of the compare register 10. Therefore, such interrupt processing is used to set the value in each buffer register. As a result, it is possible to prevent the illegal operation, for example, the ON pattern and the OFF pattern of the PWM being for different rotational positions, and to switch the PWM pattern in synchronization with the PWM cycle.

Further, in the conventional DC brushless motor real-time output circuit, when an abnormality such as a sudden drop of the power supply voltage or an abnormality such as a sudden overcurrent of the power supply current occurs, such an abnormality is externally detected. An external interrupt is generated for the single-chip microcomputer by detection with a comparator, etc., and the single-chip microcomputer rewrites the contents of the output latch as an interrupt process to perform fail-safe output.

[0041]

However, in the conventional DC brushless motor real-time output circuit as described above, since the fail-safe output at the time of synthesizing the inverter signals in the single-chip microcomputer is performed by the external interrupt processing, high speed operation is achieved. There is a problem that an interrupt processing circuit and a CPU capable of high-speed software processing are indispensable.

Further, the interrupt processing may be suspended due to the determination of the priority order or the like, and considering the soft processing time, a time of several μs to several tens of μs is required. Therefore, it is required to protect the driver against overcurrent. There is a problem in that the driver may be destroyed in time for the response time.

Therefore, the present invention has been made in view of the above problems, and effectively protects a driver from an overcurrent,
It is another object of the present invention to provide a real-time output circuit for a DC brushless motor, which can appropriately deal with a system power failure.

[0044]

To achieve the above object, the present invention provides a real-time output circuit for a DC brushless motor having a function of transferring the contents of a buffer register to an output latch based on a timer output signal. Provided is a real-time output circuit for a DC brushless motor, which includes a selection circuit for selecting an external interrupt signal as a transfer trigger in addition to a signal.

According to the real-time output circuit for DC brushless motor of the present invention, the transfer timing from the buffer register to the output latch can be selected not only by the timer output signal but also by the external interrupt signal. It is possible to realize a high-speed response that is not affected by the interrupt processing hold time required by the circuit, the CPU software processing time, and the like.

[0046]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a real-time output circuit for a DC brushless motor according to an embodiment of the present invention.

Referring to FIG. 1, the DC according to the present embodiment.
The real-time output circuit for the brushless motor is a timer counter 1 which is an up counter that counts clocks.
A buffer register 2 and a compare register 3 in which the PWM ON timing is set, a buffer register 4 and a compare register 5 in which the PWM OFF timing is set, and a master buffer register 6 and a slave in which the PWM ON pattern is set. A buffer register 7, a master buffer register 8 and a slave buffer register 9 in which the OFF pattern of PWM is set, and P
A compare register 10 in which the WM cycle is set, an output latch 12, gate circuits 17 and 18, and a gate circuit 1
The main configuration includes a mode register 16 for controlling the Nos. 7 and 18, and a slave buffer register 22 holding a fail-safe output pattern.

Next, the operation of the DC brushless motor real-time output circuit according to the present embodiment will be described with reference to FIG.

Since 0 is set in the compare register 3, the PWM ON pattern set in the slave buffer register 7 is transferred to the output latch 12 based on the coincidence signal 11 between the timer counter 1 and the compare register 3. It

Further, the PWM OFF pattern set in the slave buffer register 7 is transferred to the output latch 12 based on the coincidence signal 13 between the timer counter 1 and the compare register 5.

Timer counter 1 and compare register 10
The timer counter 1 is cleared on the basis of the coincidence signal with, and an interrupt request is generated. At the same time, the contents of the buffer register 2 to the compare register 3, the contents of the buffer register 4 to the compare register 5, the contents of the master buffer register 6 to the slave buffer register 7,
The contents of the master buffer register 8 are transferred to the slave buffer register 9, respectively.

Since the timer counter 1 continues counting from 0 again, the PWM ON pattern and OFF pattern are repeated, and as a result, the PWM output is continuously output.

Here, in the DC brushless motor real-time output circuit according to the present embodiment, when the external interrupt signal 14 is applied to the slave buffer register 7, the contents of the slave buffer register 9 are the same as the match signal of the compare register 5. That is, the PWM OFF pattern is transferred to the output latch 12.

When the external interrupt signal 15 is applied to the slave buffer register 22, the content of the slave buffer register 22 is replaced by the match signal of the compare register 20, that is, the fail-safe output pattern (all drivers are turned off here). "000000
0 ″) is transferred to the output latch 12.

By doing so, the PWM output can be turned off by the external interrupt signal 14 and the fail-safe output can be performed by the external interrupt signal 15 by hardware.

The signal of the overcurrent detection circuit can be used as the input of the external interrupt signal 14, and thus protection of the driver transistor from overcurrent can be achieved. Further, the signal of the power supply voltage monitoring circuit can be used as the input of the external interrupt signal 15, and thus the fail-safe output can be obtained when the power is cut off.

Whether the external interrupt signals 14 and 15 are valid as the transfer timing to the output latch 12 is easily determined by controlling the gate circuits 17 and 18 based on the setting in the mode register 16. be able to.

Further, it is possible to perform software processing to be further added by the interrupt processing activated based on the external interrupt signals 14 and 15.

Further, another pattern of fail-safe output can be set in the master buffer register 21 and transferred to the slave buffer register 22 as needed.

As described above, the D according to the present embodiment
In the C brushless motor real-time output circuit, since the data transfer from the buffer register to the output latch is directly controlled by hardware, a sufficient response is possible in a time of about 2 clocks, and even if the clock pitch is 200 ns, 0. It can respond in about 4 μs. In addition, since the interrupt response mechanism does not intervene, the response speed is not affected even when other interrupt processing is being executed, and since there is no CPU intervention, the response speed is affected even with a low-speed 8-bit CPU. There is no advantage.

Although one embodiment of the present invention has been described above, the present invention is not limited to such an embodiment and includes various embodiments according to the principle of the present invention.

[0063]

As described above, according to the real-time output circuit for a DC brushless motor of the present invention, the timing of transferring the contents of the buffer register is set to the timer output signal (for example, the coincidence signal between the timer counter and the compare register). Not only is it possible to select based on the external interrupt signal, it is possible to realize a high-speed response regardless of the interrupt response speed and software processing speed.
The fail-safe output for protecting the driver transistor from an overcurrent due to the interruption of the WM output and for dealing with the system power-off can be performed more reliably than the conventional interrupt processing.

Further, according to the real-time output circuit for the DC brushless motor of the present invention, it is possible to use the interrupt processing time which is no longer needed for other purposes, so that the load of software design and development can be reduced. it can.

Further, according to the DC brushless motor real-time output circuit of the present invention, since the interrupt response circuit can be realized with a relatively simple structure, a consumer CPU having a relatively low processing speed is adopted. Therefore, the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a real-time output circuit for a DC brushless motor according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a DC brushless motor.

FIG. 3 is a circuit diagram of a driver for a three-phase DC motor.

FIG. 4 is a timing chart of an inverter signal applied to a three-phase DC motor driver.

FIG. 5 shows the line current in the DC motor and D
It is a simplified vector diagram for explaining the direction of the magnetic field generated in the coil in the C motor.

FIG. 6 is a block diagram showing a configuration of a conventional real-time output circuit for a DC brushless motor.

FIG. 7 is a timing chart for explaining PWM output in a conventional real-time output circuit for a DC brushless motor.

[Explanation of symbols]

 1 timer counter 2, 4, 19 buffer register 3, 5, 10, 20 compare register 6, 8, 21 master buffer register 7, 9, 22 slave buffer register 11, 13 compare register match signal 12 output latch 14, 15 external interrupt Signal 16 Mode register 17, 18 Gate circuit 23 AC100V power supply 24 AC / DC converter 25 DC200V power supply 26 Voltage / current detection circuit 27 Voltage signal 28 Current signal 29 Inverter waveform generation circuit 30 Driver 31 Inverter signal 32 DC motor 33 Rotor position detection circuit 34 level shifter 35 DC / DC converter 36 power supply wiring P (DC200V) 37 power supply wiring N (DC0V) 38 U-phase wiring 39 V-phase wiring 40 W-phase wiring 41, 42, ..., 46 Transistor 47 Inverter signal UP 48 Inverter signal VP 49 Inverter signal WP 50 Inverter signal UN 51 Inverter signal VN 52 Inverter signal WN 53 Inverter signal pattern (U-V) 54 Inverter signal pattern (U-W) 55 Inverter signal pattern (V-W) 56 Inverter signal pattern (V-U) 57 Inverter signal pattern (W-U) 58 Inverter signal pattern (W-V)

Claims (5)

[Claims] 1. A real-time output circuit for a DC brushless motor having a function of transferring the contents of a buffer register to an output latch based on a timer output signal, for selecting an external interrupt signal as a transfer trigger in addition to the timer output signal. A real-time output circuit for a DC brushless motor, which includes a selection circuit. 2. A first buffer register which holds a bit pattern corresponding to an inverter signal in an active period of pulse width modulation, and a second buffer register which holds a bit pattern corresponding to an inverter signal in an inactive period of pulse width modulation. A real-time output circuit for a DC brushless motor having a function of transferring the content of the first buffer register or the content of the second buffer register to an output latch based on a timer output signal, In addition to the timer output signal, the external interrupt signal
Real-time output circuit for a DC brushless motor, including a selection circuit for selecting as a transfer trigger for the buffer register of the above. 3. A third means for holding a fail-safe output pattern.
Further including a buffer register, and an external interrupt signal in addition to the timer output signal,
3. The real-time output circuit for a DC brushless motor according to claim 2, further comprising a selection circuit for selecting it as a transfer trigger for the buffer register. 4. The real-time output circuit for a DC brushless motor according to claim 1, wherein a detection signal of a driver overcurrent is used as the external interrupt signal. 5. The real-time output circuit for a DC brushless motor according to claim 1, wherein a monitor signal of a power supply voltage is used as the external interrupt signal.