CN102082535B - Brushless direct current motor speed detector based on hall element and control method thereof - Google Patents

Abstract

The invention relates to a brushless direct current motor speed detector based on a hall element and control method thereof. The brushless direct current motor speed detector based on the hall element is characterized by comprising a hall signal processing unit, a single chip micyoco processing unit and an external interface unit, wherein the hall signal processing unit receives a hall signal input by the hall element of the brushless direct current motor and output the hall signal subjected to filter shaping to the single chip micyoco processing unit; the single chip micyoco processing unit outputs speed information through the external interface unit after core algorithm processing is carried out on the signal input by the hall signal processing unit; and the external interface unit is provided with a 5 V logic level external output serial interface and a 3.3V logic level external output serial interface. The control method of the brushless direct current motor speed detector based on the hall element comprises: carrying out device initialization; executing a serial port interrupt service routine when a serial port interruption request exists; executing a timer interrupt service routine when a timer request exists; and finishing a loop control process if a finish order exists. According to the invention, a special velocity measurement module is designed by utilizing the velocity measurement function of the hall element, and information is transmitted to the outside through a serial port, which is convenient for the systemic integration; and the problem of velocity measurement fluctuation is solved preferably, a trouble report mechanism is provided, and the universality is better.

Description

A kind of brushless DC motor speed measurement device and control method thereof based on Hall element

Technical field

The present invention relates to a kind of motor speed measuring technology, specifically a kind of brushless DC motor speed measurement device and control method thereof based on Hall element.

Background technology

Permanent-magnet brushless DC electric machine has good speed adjusting performance, such as stepless speed regulation, speed-regulating range width, high efficiency etc., is widely used in recent years in the underwater robot propeller drive system.Consider the design of simplifying propeller mechanical structure, the signal of the hall detector of general direct employing motor self carries out position and speed feedback, does not increase other position and speed detecting element.Adopt hall signal that rotating speed is measured two kinds of methods of common employing: a kind of is to use one road hall signal to measure, because one-channel signal resolution is lower, feedback cycle is long, usually is used in the High-speed Control field; A kind of is to utilize three road hall signals, by logical circuit or algorithm, produces 6 times to the frequency-doubled signal of one road hall signal frequency, then it is measured.But these two kinds of methods are positioned with strict requirement to Hall element on the motor stator circumference, when Hall element when the motor stator circumference is positioned with error, the width of adjacent two positive pulses will be inconsistent, causes the fluctuation of speed that records very large.

Summary of the invention

For above shortcomings part in the prior art, the technical problem to be solved in the present invention provides a kind of modularization, interface is simple and test the speed fluctuation less brushless DC motor speed measurement device and control method thereof based on Hall element.

To achieve these goals, the technical solution used in the present invention is:

The brushless DC motor speed measurement device that the present invention is based on Hall element comprises hall signal processing unit, single-chip microcomputer processing unit and external interface unit, wherein the hall signal processing unit receives the hall signal of the Hall element input of brshless DC motor, carries out exporting the single-chip microcomputer processing unit to behind the filter shape; After the signal that the single-chip microcomputer processing unit is inputted the hall signal processing unit carries out the core algorithm processing, by external interface unit output speed information; The external interface unit has 5V and the external output string line interface of 3.3V logic level.

Described hall signal processing unit has rc filter circuit and schmitt inverter, wherein the input of rc filter circuit is connected to the hall signal of Hall element input, output is connected to the input of schmitt inverter, and the signal of schmitt inverter after with shaping exports the single-chip microcomputer processing unit to.

Apparatus of the present invention also have the logic level converter unit, comprise Voltage stabilizing module and logic level transition module, Voltage stabilizing module converts outer power supply source to working power that the logic level transition module needs, and the logic level transition module provides logic level external output string line interface for the external interface unit.

The control method that the present invention is based on the brushless DC motor speed measurement device of Hall element may further comprise the steps:

Start-up routine carries out device initialize;

Serial ports interrupt requests or timer interrupt requests have been judged whether;

When the serial ports interrupt requests is arranged, carry out the serial ports interrupt service routine;

When the timer request is arranged, carry out the timer interrupt service routine;

If the finish command is arranged, end loop control procedure then.

Described timer interrupt service routine may further comprise the steps:

Detect the state of hall signal;

Enter the processing unit of corresponding state according to above-mentioned signal condition, carry out calculating and the processing of motor speed;

Preserve the current state value, withdraw from interruption.

The state of described hall signal is 6, corresponding 6 processing units, and state processing unit program idiographic flow is:

Current state value and front state value are compared, if both equate that direction and the size of rotating speed remain unchanged;

If front state value equates that with the preorder state value the big or small setting party of Calculation Speed is to being forward;

If front state value equates with the postorder state value of current state value, the size of Calculation Speed, the setting party is to being reverse;

If for other values then be set as malfunction.

The following formula that passes through of described motor speed calculates:

$n_i=\frac{60f_0}{\underset{j=i}{\overset{i-6N_0+1}{\mathrm{\Σ}}}{T}_j}---\left(3\right)$

F wherein ₀Be the clock frequency of counter, T _i=m _i-m _I-1, m _iBe the reading of i next state conversion hour counter, N ₀Be the motor pole logarithm.

Described serial ports interrupt routine may further comprise the steps:

The character that external microcontroller sends expression communication beginning represents to begin receive data to one-chip computer module;

After one-chip computer module receives the character of expression communication beginning, the upper byte of beginning transmission speed data;

After external microcontroller received upper byte, the character that the transmission expression begins to receive the upper byte data was to one-chip computer module, and the expression upper byte is received, begins to accept low byte;

One-chip computer module sends low byte after receiving and representing to begin to receive the character of upper byte data;

After external microcontroller is received low byte, the upper byte low byte is combined as complete velocity information, the size of extraction rate then, direction, the information of fault, sign off.

Adopt sliding window summation algorithm with 6N ₀Inferior summation is converted into twice summation, and motor speed formula manipulation algorithm is as follows:

Define overall array A[6N ₀], global variable bcnt, atop, sum, local variable T, and they are initialized as 0;

Carry out T=m _i-bcnt, bcnt=m _i, sum=sum-A[atop]+T, A[atop]=T, if atop=atop+1 is atop=6N ₀, atop=0 then, present speed=6f ₀/ sum; m _iValue for recording counter; N ₀Be the motor pole logarithm; f ₀Clock frequency for counter;

The rotating speed that records is averaged value filtering, obtain desirable motor speed.

The present invention compared with prior art has more and has the following advantages:

1. function modoularization, interface is simple.The function that the present invention will utilize Hall element to test the speed extract, and has designed special speed measuring module, externally by the serial ports transmission of information, is convenient to the integrated of system.

2. the fluctuation of testing the speed is less.Original frequency multiplication speed-measuring method is improved, proposed solution for common brshless DC motor Hall element in the problem that the motor stator circumference is positioned with error, thereby preferably resolve the problem of the fluctuation of testing the speed.

3. possesses Trouble Report mechanism.When Hall element goes wrong, module can be uploaded fault message when speed measuring function went wrong, and speed measuring module possesses auto restore facility when of short duration Failure elimination, uploads correct velocity information.

4. versatility is better.This invention versatility is stronger, also can be used for the various common brshless DC motors field of testing the speed.

Description of drawings

Fig. 1 is apparatus of the present invention structured flowchart;

Fig. 2 is apparatus of the present invention integrated circuit schematic diagram;

Fig. 3 A is invention control method main program flow chart;

Fig. 3 B is interrupt requests process flow diagram in the invention control method;

Fig. 4 is the timer interrupt service routine flow chart in the control method of the present invention;

Fig. 5 is the state processing unit program flow diagram in the control method of the present invention.

Embodiment

Below in conjunction with accompanying drawing the present invention is described in further detail.

As shown in Figure 1, a kind of brushless DC motor speed measurement device based on Hall element of the present invention comprises hall signal processing unit, single-chip microcomputer processing unit and external interface unit, wherein the hall signal processing unit receives the hall signal of the Hall element input of brshless DC motor, carries out exporting the single-chip microcomputer processing unit to behind the filter shape; After the signal that the single-chip microcomputer processing unit is inputted the hall signal processing unit carries out the core algorithm processing, by external interface unit output speed information; The external interface unit has 5V and the external output string line interface of 3.3V logic level.

Described single-chip microcomputer processing unit is realized the process of testing the speed by the realization of the responsible core algorithm of operation by the control program of operation motor measurement mechanism.

The hall signal processing unit has rc filter circuit and schmitt inverter, wherein the input of rc filter circuit is connected to the hall signal of Hall element input, output is connected to the input of schmitt inverter, and the square-wave signal of the standard that schmitt inverter forms after with filter shape exports the single-chip microcomputer processing unit to.

Also has the logic level converter unit, comprise Voltage stabilizing module and logic level transition module, Voltage stabilizing module converts outer power supply source to working power that the logic level transition module needs, and the logic level transition module provides logic level external output string line interface for the external interface unit.

The external interface unit comprises 5V logic level serial line interface, 3.3V level logic serial line interface, and power interface and hall signal interface, motor speed measuring device of the present invention externally carries out serial communication by the level logic serial line interface, and power interface connects the 5V power supply; The hall signal interface connects 5 lines of motor Hall element output.

The electrical schematic diagram of motor speed measuring device of the present invention as shown in Figure 2, the 5V power supply is given whole motor speed measuring device power supply by the 4th, 5 pins of the 1st terminal J1, the 5V power supply is transformed into 3.3V through Voltage stabilizing module U3 (SPX1117-3.3V), gives the 1st, 2 logic level transition U12_1, U12_2 power supply; Hall signal HA, HB and HC are through 1,2 and 3 pins of the 1st terminal J1, then through the 1st～6 resistance R 1～R6 with after being integrated in the filtering shaping circuit that the 1st～6 inverter modules U1A in the 74HC14 schmitt inverter～U1F forms, be linked into the PA mouth of the one-chip computer module U2 (ATMEGA8515L) of single-chip microcomputer processing unit.The serial ports pin of one-chip computer module U2 is connected to the pin of the 2nd terminal J2, externally carries out serial communication, is output as the 5V logical signal.Microcontroller serial port is leaded molded to carry out being connected to after the level translation pin of the 3rd terminal J3 through the 1st, 2 logic level transition module U12_1, U12_2, externally carries out serial communication, output be the 3.3V logical signal.

Shown in Fig. 3 A, 3B, the control method that the present invention is based on the brushless DC motor speed measurement device of Hall element may further comprise the steps:

Start-up routine carries out entering recurrent state behind the device initialize;

Serial ports interrupt requests or timer interrupt requests have been judged whether;

When the serial ports interrupt requests is arranged, carry out the serial ports interrupt service routine;

When the timer request is arranged, carry out the timer interrupt service routine;

If the finish command is arranged, end loop control procedure then.

Described interrupt handling routine is mainly carried out 2 interrupt service routines, is respectively the interruption of 50us timer and serial ports and interrupts.In the timer interrupt service routine, go out rotary speed information according to the state computation of hall signal; In the serial ports interrupt service routine, realize that described speed measuring device and external microcontroller carry out the function of handshake communication.

As shown in Figure 4, described timer interrupt service routine may further comprise the steps:

Detect the state of hall signal;

Enter the processing unit of corresponding state according to above-mentioned signal condition, carry out calculating and the processing of motor speed;

Preserve the current state value, withdraw from interruption.

The following formula that passes through of motor speed calculates:

$n_i=\frac{60f_0}{\underset{j=i}{\overset{i-6N_0+1}{\mathrm{\Σ}}}{T}_j}---\left(3\right)$

F wherein ₀Be the clock frequency of counter, T _i=m _i-m _i-1, m _iBe the reading of i next state conversion hour counter, N ₀Be the motor pole logarithm, j is intermediate variable.

As shown in Figure 5, the state of described hall signal is 6, corresponding 6 processing units, and wherein the 1st state processing unit 0 program idiographic flow is:

Current state value and front state value (st0) are compared, if both equate that the size and Orientation of rotating speed remains unchanged;

If front state value equates that with preorder state value (st5) the big or small setting party of Calculation Speed is to being forward;

If front state value equates with the postorder state value (st1) of current state value, the size of Calculation Speed, the setting party is to being reverse;

If for other values then be set as malfunction.

State st0-st5 respectively with code 101,100,110,010,011,001 is corresponding.

The program circuit of the program circuit of other state processing unit and the 1st state processing unit is similar, only need to just can according to the modification of current state value its preorder state value and postorder state value, for example for the 2nd state processing unit 1, the current state value is st1, its preorder state value is st0,, its postorder state value is st2, the like.

Described serial ports interrupt service routine may further comprise the steps:

The character (present embodiment is the character " # ") that the expression communication that the external microcontroller transmission is set begins represents to begin receive data to one-chip computer module U2;

After one-chip computer module U2 receives " # ", the upper byte of beginning transmission speed data;

After external microcontroller received upper byte, the expression that transmission is set began to receive the character (present embodiment is character " 1 ") of upper byte data to one-chip computer module U2, and the expression upper byte is received, begins to accept low byte;

After one-chip computer module U2 receives " 1 ", send low byte;

After external microcontroller is received low byte, the upper byte low byte is combined as complete velocity information, the information of the size of extraction rate, direction and fault then, sign off.

Adopt two bytes to represent velocity information, the direction of the 1st bit representation motor rotation, the 2nd bit representation malfunction that tests the speed, the size of rear 14 bit representation speed, speed maximum are 16837 to turn per minute.

The basic principle of motor speed measuring of the present invention is: brshless DC motor generally adopts the rotor position detector of hall switch type, usually carries out motor commutation control with hall sensor signal.Through shaping, it is three the tunnel to differ 120 ° low-frequency pulse that the hall signal transducer sends HA, HB, HC signal, and this three road signal has formed 6 different codes in 360 ° of electrical degrees, form six kinds of different states, these six codes are 101,100,110 successively, 010,011,001.Change successively according to this order during forward, change successively against this order during counter-rotating, so the information that this three road signal is comprising rotating speed and turning to.If the motor pole logarithm is N ₀, then motor whenever turns around and just has N ₀Organize 6 different states, setting a clock frequency is f ₀Counter, motor whenever runs to a state, the value of recording counter is m _i, then motor rotating speed at this moment is

$n_i=\frac{60f_0}{m_i-m_{i-6N_0}}---\left(1\right)$

The specific procedure design philosophy of described speed measuring device is: considering counter overflow, during the problem such as numerical value is excessive, can be to be out of shape to formula (1), because

$m_i-m_{i-6N_0}=\underset{j=i}{\overset{i-6N_0+1}{\mathrm{\Σ}}}(m_j-m_{j-1})---\left(2\right)$

Make T _i=m _i-m _I-1, (1) formula is can be changed into

$n_i=\frac{60f_0}{\underset{j=i}{\overset{i-6N_0+1}{\mathrm{\Σ}}}{T}_j}---\left(3\right)$

Must reduce the summation number of times in order to accelerate computational speed, adopt sliding window summation algorithm with 6N ₀Inferior summation is converted into twice summation, and the Processing Algorithm of calculating motor speed is as follows:

(1) overall array A[6N of definition ₀], global variable bcnt, atop, sum, local variable T, and they are initialized as 0, the reading of current counter is m _i

(2) carry out T=m _i-bcnt, bcnt=m _i, sum=sum-A[atop]+T, A[atop]=T, if atop=atop+1 is atop=6N ₀, atop=0 then, present speed=60f ₀/ sum; m _iValue for recording counter; N ₀Be the motor pole logarithm; f ₀Clock frequency for counter;

(3) in the measurement of motor speed, because the pulsation of rotating speed itself, random disturbances exists, and the rotating speed that records is averaged value filtering, will reach reasonable effect.

Claims (1)

1. control method based on the brushless DC motor speed measurement device of Hall element is characterized in that may further comprise the steps:

Start-up routine carries out device initialize;

Serial ports interrupt requests or timer interrupt requests have been judged whether;

When the serial ports interrupt requests is arranged, carry out the serial ports interrupt service routine;

When the timer request is arranged, carry out the timer interrupt service routine;

If the finish command is arranged, end loop control procedure then;

Described timer interrupt service routine may further comprise the steps:

Detect the state of hall signal;

Enter the processing unit of corresponding state according to above-mentioned signal condition, carry out calculating and the processing of motor speed;

Preserve the current state value, withdraw from interruption;

The state of described hall signal is 6, corresponding 6 processing units, and state processing unit program idiographic flow is:

Current state value and front state value are compared, if both equate that direction and the size of rotating speed remain unchanged;

If front state value equates that with the preorder state value the big or small setting party of Calculation Speed is to being forward;

If front state value equates with the postorder state value of current state value, the size of Calculation Speed, the setting party is to being reverse;

If for other values then be set as malfunction;

The by the following method calculating of described motor speed: through shaping, it is three the tunnel to differ 120 ° low-frequency pulse that the hall signal transducer sends HA, HB, HC signal, this three road signal has formed 6 different codes in 360 ° of electrical degrees, form six kinds of different states, these six codes are 101,100 successively, 110,010,011,001; Change successively according to this order during forward, change successively against this order during counter-rotating, so the information that this three road signal is comprising rotating speed and turning to; If the motor pole logarithm is N ₀, then motor whenever turns around and just has N ₀Organize 6 different states, setting a clock frequency is f ₀Counter, motor whenever runs to a state, the value of recording counter is m _i, then motor rotating speed at this moment is

$n_i=\frac{{60f}_0}{m_i-m_{{i-6N}_0}}---\left(1\right)$

Consider counter overflow, during the problem such as numerical value is excessive, can formula (1) be out of shape, because

$m_i-m_{{i-6N}_0}=\underset{j=i}{\overset{{i-6N}_0+1}{\mathrm{\Σ}}}(m_j-m_{j-1})---\left(2\right)$

Make T _i=m _i-m _I-1, (1) formula can be changed into

$n_i=\frac{{60f}_0}{\underset{j=i}{\overset{i-6N_0+1}{\mathrm{\Σ}}}{T}_j}---\left(3\right)$

Described employing sliding window summation algorithm is with 6N ₀Inferior summation is converted into twice summation;

The rotating speed that records is averaged value filtering, obtain desirable motor speed;

Described serial ports interrupt routine may further comprise the steps:

The character that external microcontroller sends expression communication beginning represents to begin receive data to one-chip computer module;

After one-chip computer module receives the character of expression communication beginning, the upper byte of beginning transmission speed data;

After external microcontroller received upper byte, the character that the transmission expression begins to receive the upper byte data was to one-chip computer module, and the expression upper byte is received, begins to accept low byte;

One-chip computer module sends low byte after receiving and representing to begin to receive the character of upper byte data;

After external microcontroller is received low byte, the upper byte low byte is combined as complete velocity information, the size of extraction rate then, direction, the information of fault, sign off.

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