KR100609730B1 - Apparatus and method for detecting a velocity utilizing interrupt - Google Patents

Abstract

According to an aspect of the present invention, there is provided a speed detecting apparatus comprising: a pulse input unit receiving pulse signals from an encoder; An input pulse counter unit for detecting and counting a multiplied signal by determining an edge by a function set from pulse signals input from the signal synchronous unit; A timer processing section for generating a reference time synchronized with the multiplication signal detected by the input pulse counter section, based on the interrupts generated from the interrupt generation section and the time from the reference CPU timer; An interrupt generator for indicating the time point to be actually calculated from the reference time; A signal synchronizing unit for synchronizing the input signals A pulses and B pulses inputted to the pulse input unit; It includes a timer of the CPU as a reference.

Speed control, speed detection, motor, encoder, pulse, interrupt, M / T.

Description

Apparatus and method for detecting a velocity utilizing interrupt

1 is a schematic diagram of a general speed control system composed of a control device for driving an AC motor in the related art.

2 is a diagram illustrating a speed detection method according to the M method of the speed detection method in the encoder in the conventional speed control system.

3 is a diagram illustrating a speed detection method according to a T method among methods of detecting a speed in an encoder in a conventional speed control system.

4 is a view showing a speed detection method according to the M / T method of the speed detection method in the encoder in the conventional speed control system.

5 is a schematic diagram of a speed detection apparatus according to a preferred embodiment of the present invention.

The present invention relates to an apparatus and method for detecting a speed of a motor, and more particularly, to a speed control system including a control device for driving an AC motor. A closed loop control using a speed sensor such as an encoder by a user (closed- The present invention relates to a speed detection device and a method for optimally controlling speed by using interrupts when performing Loop Control.

In general, a general speed control system composed of a control device for driving an AC motor includes an AC power source 1, as shown in FIG. A converter 2 for converting AC power into DC power; An initial charging resistor 3 for preventing inrush current from flowing in when the power is on; MC (magnetic contactor) 4 for separating the initial charging resistance from the circuit after the inrush current is suppressed; A DC and filter capacitor 5 for smoothing the DC voltage; A variable voltage, variable frequency pulse width modulation inverter 6 composed of control switching elements such as transistors, MOSFETs, IGBTs, GTO, etc., for converting direct current into alternating current; An AC motor 7 driven by an inverter; A current detector 8 for detecting a current flowing in each of the U, V, and W phases; A main controller 9 which collects various kinds of information such as DC voltage and phase current of the inverter and instructs various driving; V / f PWM controller that applies the switching voltage to the switching element of each inverter and gate of DB switch by making PWM (Pulse Width Modulation) waveform with voltage command (V *) and frequency command (f *) input from main controller. 10; A braking device 12 that consumes regenerative energy as a resistor DB R. when the DC voltage increased due to the regenerative operation is greater than the set voltage; A temperature detector 13 for detecting the temperature of the inverter 6; And an encoder 14 which is a sensor installed to find out the motor speed.

In this system, the rectifier circuit is composed of converter (2), initial charge resistor (3), MC (4), DC reactor and filter capacitor (5), 1) suppresses inrush current at initial start-up, and 2) normal It plays a role in generating DC voltage source in operation. In such a system, if the AC power source 1 is initially input without the charge resistance, since there is no initial charge in the filter capacitor, a large inrush current flows, which causes the diode module in the converter 2 to be damaged. In order to prevent this phenomenon, an initial charging resistor 3 is required. In addition, after the inrush current is suppressed and the time of RC time constant has passed, the voltage (VDC) across the filter capacitor increases to some extent. At this time, the initial charge resistance is separated from the circuit and the MC ( 4) drive is required.

The control device for driving the AC motor uses the closed loop control for the purpose of accurately driving the frequency desired by the user using the speed controller, and one of the most important parts in the closed loop control is the speed detecting part. Since the characteristics of the controller are determined according to which method is used for this part, it is necessary to use a newer method. The sensor for detecting the speed of the AC motor in the system of FIG. 1 uses an encoder.

Currently, the encoder used to detect the speed of AC motor outputs pulse strings of A and B two phases with phase difference of 90 degrees (π / 2) and one Z phase pulse every 360 degree period. Only pulses are used for speed detection. Velocity detection is obtained by ω = dθ / dt using the angle dθ changed over a certain time dt, where dθ is obtained by the number of pulses output from the encoder. Therefore, at least one encoder pulse must be generated during the dt time for the speed detection to continue.

In addition, the speed detection method in the encoder can be divided into three large as follows.

The first is the M method as shown in FIG. The M method is a method of measuring the speed using the number of pulses m1 during a sampling period Tc of a certain period. The number of pulses counted at low speed is low, so the precision is low at low speed. Second is the T method as shown in FIG. The T method is a method of obtaining velocity information by measuring the time Tp between encoder pulses using the number of m2 clocks. At high speeds, the number of m2s is small during the Tp time, resulting in poor accuracy. Third is the M / T method as shown in FIG. The M / T method is a compromise between the M method and the T method and is most often used for actual speed measurement. Velocity is measured using the time delay Td (calculated using m2) and the number of encoder pulses m1 delayed by δT in synchronization with the encoder pulse first generated after a predetermined period of sampling time Tc.

The M / T method has been used as a general method of measuring speed at both low and high speeds, but errors may occur in the synchronized time delay (Td) when detecting the speed. This method is not the best way to use the actual speed controller.

Therefore, there is a need for an optimal speed detection method that overcomes these problems and has more appropriate and stable detection characteristics in both the low speed region and the high speed region.

The present invention is to solve the above problems, it is an object of the present invention to provide a speed detection apparatus and method that can detect a more accurate speed in the low speed region as well as the high speed region at the time of motor speed detection. This speed detection device and method are not applied to a system that does not require feedback such as open-loop, but have a feedback element such as an encoder so that closed-loop control, sensored vector control, The present invention relates to a speed detection device and a method for performing the same advanced control.

It is also an object of the present invention to provide a speed detection apparatus and method capable of improving the speed calculation than the M / T method currently used without having additional hardware configuration.

In order to achieve the above object,

According to a first aspect of the present invention, the speed detecting device for detecting the speed of the motor according to the present invention:

In the speed detection device for detecting the speed of the motor,

An encoder for outputting a plurality of pulse signals in accordance with the motor speed;

A pulse input unit configured to receive the plurality of pulse signals of the encoder;

A signal synchronizing unit for synchronizing the plurality of pulse signals from the pulse input unit;

An input pulse counter unit for detecting and counting a multiplied signal from the pulse signal inputted from the signal synchronization unit;

An interrupt generator for generating an interrupt from the synchronized plurality of pulse signals input from the signal synchronizer to indicate a time point to be actually calculated from a reference time;

A timer of the CPU serving as a reference of the speed detection device;

And a timer processing unit for generating a reference time synchronized with the detected multiplication signal based on the interrupt from the interrupt generating unit and the input signal from the timer of the CPU.

According to a second aspect of the present invention,

The interrupt generator preferably includes two timers for generating interrupts for the plurality of input synchronized pulse signals.

According to a third aspect of the present invention,

Preferably, the timer processor includes an independent timer indicating a time for calculating the speed.

Further, according to a fourth aspect of the present invention, the speed detection method for detecting the speed of the motor of the present invention is:

Receiving a plurality of pulse signals output from the encoder according to the motor speed;

Synchronizing the plurality of pulse signals;

Detecting and counting a multiplied signal from the synchronized plurality of pulse signals;

Generating an interrupt based on the synchronized plurality of pulse signals;

Generating a reference time synchronized with the detected multiplied signal based on the interrupt and an input signal from a timer of a reference CPU;

And calculating a current speed of the motor by using the count result, the interrupt, and the data of the reference time.

According to a fifth aspect of the present invention,

The reference time generation step may be performed by disabling the speed calculation interrupt at the start time and enabling the speed calculation interrupt at the completion time for the periodic interrupt service routine in the speed detection. It is preferable that the speed calculation be performed once for the fixed period interrupt.

According to a sixth aspect of the present invention,

When a valid edge capable of speed detection occurs after the periodic interrupt service routine, it is preferable to process the speed calculation interrupt as a result after the generation of the valid edge.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to an embodiment of the speed detection apparatus and method of the motor according to the present invention. Like reference numerals in the drawings denote like elements. However, in the following description, the overall speed control system of the AC motor is general to those skilled in the art to which the present invention pertains, and thus description thereof is omitted.

5 is a schematic diagram of a speed detection device for detecting a speed of a motor in an M / T method according to a preferred embodiment of the present invention in a speed control system including a control device for driving an AC motor. Such a speed detecting device has a configuration of a speed detecting part of the inverter in the speed control system as shown in FIG.

The operation of the speed detection device is as follows.

First, the pulse signals generated from the encoder are input to a pulse input unit (㉮). In a general case, the decoder logic circuit, which is a signal synchronization unit, detects an edge signal for each of the input pulse signals, synchronizes and multiplies A phase pulses and B phase pulses, which are input signals, and multiplies them. By counting m using QD1_POSD in i), the number of times the AC motor rotates is received. The pulse inputted to the input pulse counter section has the possibility of generating an interrupt along each edge. At this time, the interrupt generator receives the synchronized A and B pulse signals output from the decoder logic circuit, and according to the signal synchronized with the signal input from the encoder, the quad timer B0 for the A pulse and Interrupts are generated by quad timer B3 for B pulses. The timer processing section includes a quad timer B2 (preferably 1 msec), which is a new independent timer as a portion representing time for calculating the speed. The quad timer B2 generates a reference time for speed calculation based on the signal from the timer of the CPU (clock, 40 MHz) as a reference. Based on the interrupts from the interrupt generator and the reference time from quad timer B2, the timer processor calculates a time T (t _new ).

More specifically, the speed calculation operation of the input pulse counter unit, the timer processing unit, and the interrupt generation unit in relation to the drive device of the AC motor will be described as follows. In the constant-cycle interrupt (1msec) service routine of the speed control system, the interrupt for speed calculation is disabled at the start, and the interrupt for speed calculation is enabled at the completion, thereby valid data. The operation of applying the equation does not increase indefinitely and can be calculated only once per 1 msec. However, if a valid edge capable of speed detection occurs after the periodic interrupt service routine, it will detect the number of pulses and time T after processing and process the interrupt service routine for speed calculation. When the valid edge detects the speed detection interrupt signal, the current speed is calculated using the data detected at that time. According to this speed detection method, an improved speed calculation is possible without additional hardware configuration compared to the conventional M / T method.

In addition, the present invention is not limited to the above-described embodiment, and it is a matter of course that modifications and variations can be made by those skilled in the art without departing from the spirit of the present invention. Accordingly, the scope of the present invention is limited only by the claims that follow.

 This configuration allows the present invention to operate the speed detection portion of the inverter more accurately and stably. As a result, the area that can be detected at low speed becomes wider and more accurate in current hardware, and it has high response even in the high speed area and enables accurate speed detection. It becomes possible.

Claims (6)

In the speed detection device for detecting the speed of the motor, An encoder for outputting a plurality of pulse signals in accordance with the motor speed; A pulse input unit configured to receive the plurality of pulse signals of the encoder; A signal synchronizing unit for synchronizing the plurality of pulse signals from the pulse input unit; An input pulse counter unit for detecting and counting a multiplied signal from the pulse signal inputted from the signal synchronization unit; An interrupt generator for generating an interrupt from the synchronized plurality of pulse signals input from the signal synchronizer to indicate a time point to be actually calculated from a reference time; A timer of the CPU serving as a reference of the speed detection device; And a timer processing unit for generating a reference time synchronized with the detected multiplication signal based on the interrupt from the interrupt generating unit and the input signal from the timer of the CPU. The method of claim 1, The interrupt generator is: And two timers for generating interrupts for the input synchronized plurality of pulse signals. The method of claim 2, And the timer processing unit includes an independent timer indicating a time for calculating the speed. In the speed detection method for detecting the speed of the motor, Receiving a plurality of pulse signals output from the encoder according to the motor speed; Synchronizing the plurality of pulse signals; Detecting and counting a multiplied signal from the synchronized plurality of pulse signals; Generating an interrupt based on the synchronized plurality of pulse signals; Generating a reference time synchronized with the detected multiplied signal based on the interrupt and an input signal from a timer of a reference CPU; And calculating a current speed of the motor by using the count result, the interrupt, and the data of the reference time. The method of claim 4, wherein The reference time generation step may be performed by disabling the speed calculation interrupt at the start time and enabling the speed calculation interrupt at the completion time for the periodic interrupt service routine in the speed detection. A speed detection method, characterized in that the speed calculation is performed once for the stationary interrupt. The method of claim 5, And when the valid edge capable of speed detection occurs after the periodic interrupt service routine, processing the speed calculation interrupt as a ratio after the generation of the valid edge.

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