CN1378335A - Speed Control Circuit with Dynamic Synchronous Pulse Width Modulation - Google Patents

Abstract

When the phase of motor coil is changed, the motor phase synchronous detection unit outputs a control signal to pulse width modulation control command unit, and makes the pulse width modulation control command unit output a pulse width modulation control command signal which is in phase with motor phase, then inputs the control command to drive unit for controlling motor, so that the pulse width modulation control signal and motor phase are in phase when they are changed, so that it can reduce noise when the motor is running.

Description

Speed Control Circuit with Dynamic Synchronous Pulse Width Modulation

The invention relates to a speed control circuit with dynamic synchronous pulse width modulation.

At present, the speed control devices of various DC motors or brushless fans are used to effectively realize the coil operation control, that is, to improve the power consumption during coil operation, so the existing linear drive method is changed to the pulse width modulation (PWM) control method. By controlling the rotation of the coil, the purpose of saving energy and driving with high efficiency can be achieved due to the pulse width modulation (PWM) control.

However, the above pulse width modulation control method needs to use a set of control sequences because the pulse width modulation control circuit, the control circuit and the motor coil have two sets of signals with different duty cycles, so when the motor is running , will generate operating noise and additional electronic and electromagnetic noise due to the two different duty cycles.

Although the above-mentioned pulse width modulation control circuit can provide an effective control signal for the motor drive circuit, so that the motor can save a large amount of power during operation, this control method cannot improve the noise generated by the motor during operation. One shortcoming still needs to propose a more effective solution.

Therefore, the object of the present invention is to provide a control device for controlling the pulse width modulation control signal in phase synchronization with the operation of the motor, so as to effectively reduce the noise interference generated by the motor during operation.

In order to achieve the above object, the speed control circuit with dynamic synchronous pulse width modulation of the present invention includes: a synchronous phase detection unit, which is connected to the output end of the detection circuit of coil phase change, in order to detect the duty cycle of phase change ; and a pulse width modulation control unit, one input end of which is connected to the output end of the synchronous phase detection unit, and the other input end is connected to the control speed command signal for controlling the operation of the coil drive circuit; the circuit detects that the coil After the working cycle of the phase change, the synchronously controlled speed command signal is consistent with the working cycle of the detection signal, and then input to the coil driving circuit, so that the coil speed control signal is the same as the working cycle of the coil, so as to reduce the noise during operation.

In the above circuit structure, the synchronous phase detection unit is used to obtain the phase-transformed signal of the Hall sensor, and the obtained signal is input to the pulse width modulation control unit to adjust the control speed signal to the duty cycle when commutating with the coil Similarly, in this way, the signal that can control the operation of the coil drive circuit is consistent with the duty cycle of the coil, so that the fundamental frequency of the maximum noise energy generated by the coil and the fundamental frequency of the control signal overlap each other to reduce the noise generated during the operation. noise.

In order to better understand the purpose, features and advantages of the present invention, preferred embodiments of the present utility model will be described in detail below in conjunction with the accompanying drawings.

Fig. 1 is a block diagram of the present invention;

Fig. 2 is a block diagram of a preferred embodiment of the present invention;

Fig. 3 is a block diagram of another preferred embodiment of the present invention;

Fig. 4 is a block diagram of another preferred embodiment of the present invention;

Fig. 5 is a circuit waveform diagram of the present invention;

Figure 6 is a block diagram of the actual operation of the present invention.

The present invention is a pulse width modulation device that can output synchronously with the duty cycle of the motor or fan coil. Referring to FIG. Er detection signal; a pulse width modulation unit 20, whose input is connected to the output end of the synchronous phase detection unit 10, in order to input pulse width modulation signal to control the action of the coil drive circuit (not shown in the figure); The synchronous phase detection unit 10 includes: an edge detection unit 11, which is connected to a Hall detection signal for detecting the phase transformation of the motor coil through the Hall signal; a first counter 12, which is connected to the The output end of the edge detection unit 11 is used to calculate the duty cycle of the Hall signal; a flip-flop 13 includes two input ends, one of which is connected to the output end of the first counter 12, and the other input end Be connected to the output end of described edge detection unit 11; A second counter 14, it is connected to the output end of described flip-flop 13; An oscillator 15, it is connected described first, second counter 12,14 Timing signal input terminals, that is, the first and second counters 12 and 14 are synchronous counters.

The working principle of the aforementioned circuit will be described below. At first, the first counter 12 is set as a division by N counter (that is, N clock pulses are counted once), and when the edge detection unit 11 detects the Hall signal For example, after the positive potential changes to a low potential or changes from a low potential to a high potential, a trigger signal is output to the first counter 12, that is, the first counter 12 starts counting, and if the counted value is X means that the signal period is N×X. When the edge detection unit 12 detects the next edge signal of the Hall signal, it means that the previous signal period is over. At this time, the flip-flop 13 will The value X counted by the first counter 12 is stored and input to the second counter 14, even if the second counter 14 becomes a division by X counter, at the same time the second counter 14 starts counting from 0 to N-1, when When counting to N-1, even the phase of the coil will change once again;

Please refer to Fig. 5 and Fig. 6 at the same time, in order to apply the present invention in the control circuit of the general fan coil, it includes a Hall sensor 40, a comparator 50 connected to the Hall sensor 40, a phase logic circuit 60 and a Drive circuit 70; because want to change the rotational speed of motor coil 30, so output a pulse width modulation signal of control rotational speed and send to described drive circuit 70 through phase logic circuit 60, make motor coil 30 begin to change rotational speed, wherein when Hall sensor 40 It can be seen from detecting the Hall signal of phase change that when the polarity of the coil changes, the two adjacent pulse wave periods of the Hall sensor 40 are approximately the same, so the first counter can be used to estimate the time of a phase conversion as a coil The conversion time of the next phase, using this estimated time, makes the control speed command and the next coil duty cycle the same, so as to achieve the purpose of synchronization between the two.

To achieve that the signal period of the control speed command is the same as the duty cycle of the motor coil, the output signal of the second counter 14 can be input to the pulse width modulation unit 20, and after a comparison with the signal of the control speed command, Then output a pulse width modulation signal that is the same as the duty cycle of the motor to the driving circuit 70 of the coil.

Because there are three types of signal forms of the existing control speed command, the following descriptions are as follows for the pulse width modulation unit 20 for different control speeds in conjunction with each circuit diagram: 1. Analog voltage type:

2, the pulse width modulation unit 20 includes: a digital-to-analog converter 21, which converts the digital signal output by the second counter 14 into an analog signal; a comparator 22, whose input terminal One controls the speed command, and the other input end is connected to the output end of the digital-to-analog converter 21;

Please refer to FIG. 5, because the control speed signal is an analog voltage signal, and the output signal Q of the second comparator 14 is a digital signal. The pulse width modulation signal with the same phase of the signal duty cycle, so after the signal is converted into an analog signal R by the digital-to-analog converter 21, the control speed command is compared with the output signal Q by the comparator 22 , as shown in FIG. 5 , a pulse width modulation signal PWM for controlling the coil drive circuit can be output.

Two-digit format:

Referring to Fig. 3, the pulse width modulation unit 20 is composed of a digital comparator 23, the input of which is connected to the output of the second counter 14, because the control speed signal is a digital signal, and the first The output signal Q of the second counter 14 is also a digital signal, so after directly comparing the two signals, the digital control speed signal can be adjusted to be consistent with the duty cycle of the output signal Q of the second comparator 14, and The pulse width modulation signal is output, and because the second comparator 14 obtains the Hall signal as a trigger signal, the pulse width modulation signal is the same as the coil duty cycle.

Triple pulse width modulation:

Please refer to shown in Fig. 4, because the control speed command is a pulse width modulation signal, the same as the coil duty cycle for converting the command signal, so the pulse width modulation unit includes: an edge detection unit 24, its input terminal The control speed command connected to the pulse width modulation type is formed by a positive edge detection unit in this embodiment; a third counter 25, whose timing signal input end is connected to the above-mentioned oscillator 15, and its trigger enabling input terminal is connected to the output terminal of the above-mentioned positive edge detection unit 24, wherein the third counter 25, in this embodiment, it is made of a division by N counter; a flip-flop 26, its input terminal is connected to the The output terminal of the third counter 25, its enabling terminal is connected to the output terminal of the above-mentioned positive edge detection unit 24; a fourth counter 27, its timing signal input terminal is connected to the oscillator 15 the same as the third counter 25; And a comparator 23, one input end is connected to the output end of the second counter 14, and the other input end is connected to the output end of the fourth counter 27;

When the positive edge detection unit 24 acquires the positive edge signal of the control speed command, it outputs to the third counter 25 as its trigger signal, when the positive edge detection unit 24 continuously detects two trigger signals , the two trigger signals represent a working cycle of the control speed signal, and during this cycle, the third counter 25 starts counting according to the clock pulse wave of the oscillator 15, that is, during the working cycle The third counter 25 counts to Y, and then when the working cycle ends, the positive edge detection circuit detects a positive edge signal, and at this time, the flip-flop 26 is about to input the Y value to the fourth The counter 27 makes it a division Y counter, and then, when the signal of the control speed command is converted from a low potential to a high potential, the fourth counter 27 can be triggered to count, and the subsequent high potential pulse signal is used to divide Y. At this time, when the fourth counter 27 counts to M in the high-potential pulse wave, it represents that the width of the effective control speed command signal is M/N. At this time, the signal of the fourth counter 27 is input to the comparison In the device 23, a comparison is made with the output signal Q of the second counter 14 to output a pulse width modulation signal for controlling the coil drive circuit that is consistent with the coil duty cycle.

It can be seen from the above that the division by N first counter set by the synchronous phase detection unit is a parameter for dividing a phase time, that is, it represents the number of different work cycles that can be divided, so the larger the value of N, the more the output control coil drive circuit The higher the resolution of the duty cycle of the pulse width modulation is, the higher the frequency of the clock pulse signal of each counter is, the synchronous pulse width modulation cycle with better synchronization accuracy can be obtained.

For this reason, the present invention can effectively reduce the operating noise when the coil is operated at low speed, and adopts a dynamic synchronous adjustment circuit to make the control command of the control drive circuit and the duty cycle of the coil the same, so that the fundamental frequency of the two in the frequency domain can be overlapped, Furthermore, the noise during operation is reduced, and compared with the existing driving circuit, it has outstanding and remarkable effects.

Claims (7)

1. Rotating-speed control circuit with dynamic synchronization pulse-width modulation it comprise:

   One synchronous phase detection unit, it is connected in the output of the testing circuit of coil phase conversion, in order to detect the work period of phase change; And

   One pulse width modulation controlled unit, one input end is connected to the output of described locking phase detecting unit, and another input is connected to the control rotating speed command signal of control coil drive circuit start;

   After described circuit detects out the work period of coil phase change, Synchronization Control rotating speed command signal is consistent with the described work period that detects signal, input to coil driver again, so that the coil speed controling signal is identical with the work period of coil, the noise when turning round to reduce.
2. 2. the rotating-speed control circuit with dynamic synchronization pulse-width modulation as claimed in claim 1 is characterized in that, the testing circuit of described coil phase conversion is a Hall element, and described locking phase detecting unit comprises:

   One edge detects the unit, and it is connected to the detection signal output of a Hall element;

   One first counter, it is connected to the output that described edge detects the unit, in order to calculate the work period of hall signal;

   One flip-flop, its input is connected to the output of described first counter, and another input is connected to the output that described edge detects the unit;

   One second counter, it is connected to the output of described flip-flop; And

   One oscillator, it is connected in the clock signal input of described first, second counter simultaneously, makes described first, second counter synchronisation counting.
3. 3. the rotating-speed control circuit with dynamic synchronization pulse-width modulation as claimed in claim 2 is characterized in that, a pulse width modulation controlled unit includes:

   One digital analog converter, it is connected to the output of described second counter, converts analog signal in order to the digital signal with described second counter output; And

   One comparator, one input end input one control rotating speed order, another input is connected to the output of described digital analog converter.
4. 4. the rotating-speed control circuit with dynamic synchronization pulse-width modulation as claimed in claim 2, it is characterized in that, one pulse width modulation controlled unit is a digital comparator, one input of described comparator is connected to the output of described second counter, and another input is connected to described control rotating speed command signal.
5. 5. as claimed in claim 2 have a dynamic synchronization pulse-width modulation rotating-speed control circuit, it is characterized in that a pulse width modulation controlled unit comprises:

   One edge detects the unit, and its input is connected to the control rotating speed command signal of pulse-width modulation type;

   One the 3rd counter, its clock oscillation input is connected to described oscillator, and it triggers the activation input and is connected to the output that described edge detects the unit;

   One flip-flop, its input is connected to the output of described the 3rd counter, and its activation end is to be connected to the output that above-mentioned edge detects the unit;

   One four-counter, its clock oscillation input is connected to the oscillator identical with the 3rd counter; And

   One comparator, one input end are connected to the output of described second counter, and another input is connected to the output of described four-counter.
6. 6. the rotating-speed control circuit with dynamic synchronization pulse-width modulation as claimed in claim 5 is characterized in that, it is that a positive edge detects the unit that described edge detects the unit.
7. 7. the rotating-speed control circuit with dynamic synchronization pulse-width modulation as claimed in claim 5 is characterized in that, it is that a negative edge detects the unit that described edge detects the unit.

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