KR0115471Y1 - Signal compensation circuit for sensorless motor control - Google Patents

Abstract

The present invention relates to a signal correction circuit for sensorless motor drive control, and conventionally, the hall sensor has a disadvantage in that the manufacturing cost increases by using a separate sensor and the lifespan is shortened due to damage of the Hall element. In addition, the sensorless driving method is not only very serious speed imbalance at low speed but also very large torque unbalance, so there is a problem that precise motor control cannot be performed at low speed even with soft switching. In view of this point, the present invention is designed to maintain a constant switching energization period by detecting a square wave by sensing a peak level by detecting a back emf on a motor and then amplifying a certain level and detecting hysteresis. The switching energization section is always constant by correction and generates a signal without torque ripple, so that constant speed control of the motor without speed unevenness is possible even in case of disturbance. Especially, the low speed below 200rpm using sensorless There is an effect that smooth drive control can be performed during drive control.

Description

Signal correction circuit for sensorless motor drive control

1 is a motor driving circuit diagram using a conventional Hall element.

2 is a structural diagram of a conventional Hall element.

3 is a block diagram of a motor driving circuit using a conventional sensorless.

4 is a waveform diagram of a phase voltage and a switching signal in FIG.

5 is a block diagram showing an embodiment of the present invention.

6 is a circuit diagram of a switching correction unit in FIG.

7 is a waveform diagram of each part in FIG.

* Explanation of symbols for main parts of the drawings

1: motor drive 2, 16: motor

3: Hall element 11: Start control unit

12: timing control unit 13: soft switching driver

14: output drive unit 15: inverter

17: phase detection unit 18: switching correction unit

The present invention relates to a motor drive control, and in particular, a signal correction circuit for controlling a sensorless motor drive that controls smooth driving even at a low speed by correcting to maintain a constant switching energization period by detecting a phase voltage in controlling a drive of a sensorless motor. It is about.

In general, a method of controlling the driving of a small precision motor includes a method using a Hall element as shown in FIG. 1 and a sensorless method as shown in FIG.

In the conventional motor drive control circuit using the Hall element, when the power is turned on and the motor 2 is driven by the motor drive unit 1, the flux of the permanent magnet mounted on the rotor of the motor 2 is changed to the Hall element 3. The motor driver 1, which is induced at the output of the hall element 3 and outputs a switching signal to the motor 2, controls the driving.

Here, the Hall element 3 has a structure as shown in FIG. 2, and is mounted on the lower portion of the permanent magnet in which a certain number of N and S poles are alternately arranged on the rotor of the motor 2.

In particular, in the case of a three-phase voltage motor, the Hall elements should be normally spaced 120 ° apart. However, since the rotor has a permanent magnet with several N and S poles, the Hall element mechanically obtains an electrical angle of 120 °. The angle is placed at (2 / NP * 120 °).

In addition, the conventional motor drive control circuit using a sensorless is a method of driving the motor by using the back emf (electric motive force) induced in the motor.

That is, when the voltage is applied, the initial setting value is applied to the timing controller 12 by the start controller 11, and when the timing controller 12 outputs a switching signal, the soft switching driver 13 starts the driving section. The motor 16 rotates as the output driving unit 14 outputs a base driving signal to the inverter 15 and drives the power transistor according to the output of the soft switching driver 13.

At this time, when the phase detector 17 detects the back emf from the phase current for driving the motor, the timing controller 12 receiving the sine wave signal of the phase detector 17 as shown in FIG. It outputs a square wave switching signal.

Here, in order to induce the back emf on the motor 16 to obtain a constant interval of switching time according to the speed of the motor 16, that is, sensing of the switching reference signal is performed in a constant phase sequence such as U, V, and W. shall.

Accordingly, the soft switch driver 13 receiving the output of the timing controller 12 sets the maximum-minimum driving period, and the output driver 14 receiving the output of the soft switching driver 13 receives the inverter ( The driving of the motor 16 is controlled by outputting a base driving signal, which is a square wave of a TTL level, to 15). However, the conventional method using the Hall sensor has a disadvantage in that the manufacturing cost increases by using a separate sensor and the life is shortened due to damage of the Hall element.

In addition, the conventional sensorless drive control method is driven by using a back emf formed when the motor rotates without using a separate switching sensor, so that the structure is simpler than the hall element using method, so that the manufacturing cost is low and the life is long. It has relatively good performance even in high speed control.

Nowadays, audio / video multimedia and the like require ultra-thin trends and very high precision, and a low speed drive is necessary because the range of use is not only used in a specific area but also in the full speed range.

However, in the conventional sensorless drive control method, the switching is relatively good at a high speed but does not properly drive the inverter at a low speed. That is, the conventional sensorless driving method detects and switches the back emf induced during the motor rotation, so that the voltage of the induced back emf is too small at 300 rpm or less so that the sensorless back emf detection is performed.

Not only is it wrong, but the driver's drive section (T1 ≠ T2) is very unbalanced.

Therefore, the conventional driving method using the sensorless not only achieves a very serious speed imbalance at low speeds but also a very large torque unbalance, so there is a problem that precise motor control cannot be performed at low speeds even with good soft switching.

Therefore, the motor drive using the conventional sensorless cannot smoothly control the drive under the low speed of 300rpm. Therefore, it is not used in the low speed range and the motor is driven only in the medium-high speed range to remove the parts requiring low speed and implement the system. Alternatively, a low speed motor was inserted to drive low speed.

In order to solve this problem, the present invention detects the back emf on the motor, amplifies a certain level, and outputs a square wave by sensing a peak value by detecting hysteresis. A signal correction circuit for driving control is devised.

The present invention provides a start control unit for setting the on / off of the power supply to achieve the above object, a timing control unit for zero crossing the switching signal detected in accordance with the output of the start control unit and the driving of the motor, and the timing control A soft switching driver for calculating a negative output to set a maximum-minimum interval, an output driver for calculating a TTL level square wave to the inverter by calculating an output of the soft switching driver, and a motor for driving in accordance with the current conversion of the inverter. A motor driving circuit comprising a phase detector for receiving a switching signal according to a back emf and outputting the switching signal to the timing controller, wherein the phase is corrected by amplifying the back emf of the motor and comparing it with a reference voltage Vref. And a switching correction unit output to the detection unit.

Hereinafter, with reference to the accompanying drawings of the present invention in detail as follows.

5 is a circuit diagram of an embodiment according to the present invention, as shown therein, the start control unit 11 for setting the on / off of the power supply, the output of the start control unit 11 and the drive of the motor 16. A timing control unit 12 for zero crossing the detected switching signal, a soft switching driver 13 for calculating an output of the timing control unit 12 and setting a maximum-minimum section, and the soft switching driver 13 Output driver 14 outputting a TTL level square wave to inverter 15 and a switching signal according to back emf on motor 16 driven according to the current conversion of inverter 15 The phase detection unit 17 which receives the output signal to the timing control unit 12 and amplifies the back emf of the motor 16 and compares it with the reference voltage Vref to correct the switching signal to the phase detection unit 17. Output switching correction unit 18 Configure.

As shown in FIG. 6, the switching correction unit 18 includes amplifiers A1-A3 for a predetermined level amplification of each phase voltage applied to the motor 16, and outputs of the amplifiers A1-A3. A comparator A4-A6 outputs a switching signal that is a square wave according to the correction compared with the reference voltage Vref.

When described in detail with reference to Figure 7 the operation and effect of the embodiment of the present invention configured as described above.

When a voltage is applied, an initial setting value is applied to the timing control 12 by the start controller 11, and when the timing control 12 outputs a base signal, the soft switching driver 13 sets a driving period and the soft In response to the output of the switching driver 13, the motor 16 rotates as the output driver 14 outputs the base driving signal by the inverter 15 to drive the power transistor.

At this time, as shown in FIG. 7A, when the switching correction unit 18 detects a phase back emf signal induced by an unbalanced motor 16 as well as an uneven energization period (T1 ≠ T2), the amplifiers A1-A3. ) Is inverted and amplified by the gains of the resistors R1, R2 (R3, R4) (R5, R6) to output a signal as shown in FIG.

The reason why the amplifiers A1-A3 are added is that the signal of the back emf induced at low speed is very small, so it is difficult to distinguish it from noise and the sensitivity is very bad. Therefore, the sensitivity of sensing only the signal is increased by increasing the signal-to-noise ratio. The amplification ratio is enough, so there is no need to worry about signal loss due to amplification.

That is, when the amplifiers A1-A3 receive the back emf signal induced at a low speed, the signal loss due to amplification is increased by outputting an amplified signal having a high sensitivity to sense only the back emf signal by increasing the signal-to-noise ratio. Will be prevented.

Here, in order to induce the back emf signal on the motor 16 to the switching correction unit 18 in order to obtain a switching interval of a constant interval according to the speed of the motor 16, that is, the sensing of the switching reference signal is U, V It should be done in a certain phase order such as, W.

Accordingly, when the amplifiers A1-A3 amplify the signal at a predetermined ratio, the comparators A4-A6 receiving the amplified signal are compared with the reference signal Vref, thereby detecting hysteresis and FIG. 7 (b). A peak value of the same waveform is sensed to output a signal having a very accurate switching period as shown in FIG. 7C to the input terminals Uin, Vin, and Win of the phase detector 17.

At this time, when the phase detector 17 receives the output of the switching correction unit 18 that detects and corrects the back emf from the phase current for driving the motor 16, the timing control unit 12 receives the output signal of the phase detector 17. ) Outputs a base signal by zero crossing.

Therefore, when the soft switching driver 13 receiving the output of the timing controller 12 outputs the base signal by setting the maximum-minimum driving period, the output driver 14 receiving the output of the soft switching driver 13 is input. ) Outputs a base driving signal, which is a square wave of TTL level, to the inverter 15 to control the driving of the motor 16.

That is, as the switching correction unit 18 outputs a signal whose switching energization section is always constant (T1 = T2) at any speed as shown in FIG. Without this, the sensorless motor can be driven accurately, and since there is almost no torque ripple, there is no influence of the speed unevenness caused by the torque ripple.

Therefore, even if a speed unevenness occurs due to an external unforeseen disturbance at a low speed, even if an unbalance of a switching energization section of the inverter 15 occurs from this, the constant speed control of the motor 16 is always maintained by correction. It becomes possible.

As another embodiment of the present invention, a portion of amplifying the back emf of the motor shown in FIG. 6, that is, the amplifiers A1-A3 is removed, and the signals U, V, and W of the motor are directly comparators A4-. The switching correction signal can be obtained by applying to the input terminal of A6).

Here, the amplifiers A1-A3 can be removed because the input signal may be a signal that can be sensed according to the motor to be applied. If only a simple filter using a capacitor is inserted into the input terminal of the phase detector 17, the back emf signal is generated. Detection can be performed to compensate for switching for motor drive control.

As described in detail above, the present invention generates a signal without torque ripple and the switching energization section is always constant by correction at any rpm, and thus it is possible to control the constant speed of the motor without speed unevenness even when disturbance occurs. Also, it is very useful when the Hall element cannot be used in the small precision motor and when the FG circuit using the back emf cannot be added. Especially, the smooth drive control at low speed of 200rpm or less using sensorless It can be effective.

Therefore, the present invention can be smoothly and precisely driven at a low speed of 300rpm, so that the present invention can be applied to information devices and multimedia such as CD-ROMs requiring fast access time.

Claims (3)

In a sensorless motor drive circuit that detects a phase emf signal generated from a motor and uses the signal to drive-control the motor, a switching signal inverted for each peak value by comparing the phase emf signal generated from the sensorless motor with a reference signal. A sensor correction motor drive control signal correction circuit comprising a correction signal detection stage generated. The method of claim 1, wherein the correction signal detecting stage compares a reference voltage having a peak value of a predetermined phase emf signal and a phase emf signal generated by the motor to generate a square wave which is inverted whenever the input signal becomes equal to the reference signal. Sensor correction motor drive control signal correction circuit, characterized in that consisting of one or more comparators. 2. The signal correction circuit for sensorless motor drive control according to claim 1, comprising an amplifier stage for amplifying the phase emf signal generated by the motor.