JPS59185194A - Ignition pulse control method for semiconductor devices - Google Patents

Abstract

PURPOSE:To enable to output a firing pulse having the prescribed phase by treating the first and second interrupt signals to correct the counted value of a counter, thereby eliminating the repeated rapid calculations of a microcomputer in accordance with the current phase angle applied from a vector controller and the instruction value of the inverter frequency. CONSTITUTION:The time of the inverter of firing pulses applied to a power converter (which is a current type inverter) 1 through a pulse amplifier 4 from the frequency f1 of an inverter and the instruction value of a current phase angle (beta) is calculated by a microcomputer 3, counted by a counter 6 attached externally of the microcomputer 3, the decision of the firing pulse and the procedure of the output are performed by the interrupt signal D produced at the counting up time, thereby reducing the calculating time necessary to control the microcomputer 3 via the firing pulse, and the microcomputer 3 which has relatively slow calculation can control it.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to which the Invention Pertains] The present invention provides a method for controlling the firing pulse interval of a semiconductor element in a power converter whose load is an AC motor based on a command value given for controlling the speed of the motor. The present invention relates to an ignition pulse control method for controlling ignition pulses.

[Prior art and its problems]

Vector control methods tend to be widely adopted as a control method that enables quick summer control of induction motors and other devices with a high-speed response. By the way, in vector control of an induction motor powered by the inverter using, for example, a current source inverter as a power converter, the output frequency (inverter frequency) to be supplied from the inverter to the motor and the motor The desired phase angle β of the -order current vector from the magnetic flux vector (magnetic flux axis) is given from the vector control device as a command value for motor speed control, and the thyristor is fired at the inverter frequency according to these command values. A control method is known in which the pulse interval (ignition phase) is calculated and controlled.

However, in such conventional control methods, a microcomputer (hereinafter also referred to as microcomputer) that calculates the ignition phase calculates the inverter frequency and current vector phase angle (hereinafter simply referred to as current phase angle) given as command values. It becomes necessary to quickly repeat and calculate the ignition phase according to β, which requires a microcomputer with a high processing speed, and there is less room for the microcomputer to be used for other calculation processing. There were drawbacks such as a decline in its utilization.

[Purpose of the invention]

The present invention has been made in order to eliminate the drawbacks of the prior art as described above, and therefore, an object of the present invention is to enable a microcomputer to quickly perform repetitive calculations in accordance with command values given from a vector control device, etc. It is an object of the present invention to provide an ignition pulse control system capable of outputting an ignition pulse with a required phase without the need for a ignition pulse.

[Key points of the invention]

The key point of the configuration of the present invention is to calculate the firing pulse interval for on/off control of a semiconductor element in a power converter that supplies power to an AC motor by reading a command value given for speed control of the motor. a counter for counting clock pulses, and a latch for reading the counted value of the counter into the arithmetic unit, and the arithmetic unit calculates the firing pulse interval determined by the calculation to the required number of the clock pulses. The converted value is set in the counter as a set value, and when the counter has counted the set value, it generates a first interrupt signal and inputs it to the arithmetic unit, and the arithmetic unit accordingly In the ignition pulse control method, which controls the output pattern of the ignition pulse, reads the command value at that time, and operates in the same manner thereafter,
A second interrupt signal that is generated at a constant cycle shorter than the generation cycle of the first interrupt signal is input to the arithmetic unit, and the divider calculates the command value each time it receives the second interrupt signal. At the same time, the count value of the counter at that point is read through the launch, and if the read command value is different from the previous command read value, the read counter count value is calculated according to the difference. The problem lies in that the above-mentioned counter is set again by modifying the above-mentioned counter.

[Embodiments of the invention]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, 1 is a power converter (for example, a current source inverter device), 2 is an induction motor, 3 is a microcomputer, 4 is a pulse amplifier, 5 is a latch, and 6 is a counter. Also β and f
1 is a current phase angle (β ) and the inverter frequency (f1).

FIG. 1A is an operational waveform diagram of each part in the circuit of FIG. 1.

FIG. 2 is a circuit diagram showing an inverter circuit of the inverter device as the power converter 1 in FIG. 1. In the same figure, ThR, Ths, ThT, Thx, Thy, Th
z indicates a thyristor, DR, DS, DT, D
X, DY, and Dz each represent a diode.

FIG. 2A is a time chart showing an example of the waveform of the gate firing pulse of each thyristor in FIG. 2. FIG. The main thyristors are ThR, Thz, Ths, Thx, ThT
, Thy are ignited (conducted) in the order of 120 degrees with a phase difference of 60 degrees.

Next, the circuit operation will be explained with reference to FIGS. 1 to 2A.

First, the ignition pulse applied from the microcomputer 3 to the power converter 1 via the pulse amplifier 4 has six phases with respect to one period of the inverter frequency f1, as shown in FIG. 2A. If the command value of the inverter frequency f1 given to the microcomputer 3 is constant and the command value of the current phase angle (β) with respect to the magnetic flux axis does not change, the ignition pulse will be output with a 60° phase difference in electrical angle. .

Now, if the period of the clock pulse given to the counter 6 from a clock generation source (not shown) is tc, then at a certain inverter frequency f1, the count setting value Ni of the counter 6 for determining the time point every 60 degrees of electrical angle is as follows. (1
) is given by the formula.

Ni=1/6f1tc・・・・・・・・・・・・(1)
That is, the time required for the counter 6 to count up Ni clock pulses corresponds to an electrical angle of 60'. If the command value β changes, this change is Δ
When β, the number of corresponding through clock pulses to be counted may be added to this Δβ to the count setting value determined by the above equation (1) to obtain a new setting value. The number of clock pulses to be counted corresponding to Δβ is as follows (2
) is given by the formula.

However, K360 is a constant representing the amount of command value β corresponding to 360 degrees of electrical angle.

Therefore, if each command value of the inverter frequency f1 and the current phase angle β is given at a certain point in time, the count setting value N to be counted by the counter 6 until the next ignition pulse time is given by the following equation (3).

Therefore, the microcomputer 3 can obtain the count setting value N and set it in the counter 6. Assume now that at time tn-1 in FIG. 1A, the counter 6 counts up the set value N, inputs the interrupt signal D to the microcomputer 3, and the microcomputer 3 outputs an ignition pulse. At the same time, the microcomputer 3 reads the inverter wave number f1 and current phase angle β at that time. The microcomputer 3 calculates the change Δβ with respect to the current phase angle β at the time when the previous interrupt signal was generated, calculates the count setting value N according to the equation (3), sets it in the counter 6, and starts counting.

Next, when the periodic interrupt signal C is input at time tn, the microcomputer 3
outputs a latch signal G, and latches and reads the current value Mn of the counter 6 into the latch 5. Also, at that point, read the inverter frequency f1 and the command value β of the current phase angle, and set the count setting value N according to the above formula (3).
Calculate. Next, the difference ΔNn from the previously set count setting value N is calculated and added to the current value Mn of the counter 6 (M
counter 6 with n+ΔNn) as the new count setting value.
and restart the count.

A similar procedure is performed at time tn+1.

At time tn+2, counter 6 counts and amplifies,
The interrupt signal D is input to the microcomputer 3, and the microcomputer 3 determines the current firing pulse pattern with respect to the previous firing pulse pattern according to the polarity of the inverter frequency. That is, in the explanatory diagram of the firing pulse pattern shown in FIG. 3, it is assumed that the firing pulse is outputted in pattern 2 to each of the thyristors ThR to Thy at time tn-1. If t
If the polarity of the inverter frequency when the quant set value is calculated at time n+1 is positive, then at time tn+2, an ignition pulse is output in pattern 3, which is advanced by one. Outputs the inverter peripheral firing pulse. If the polarity is positive, pattern 5 is followed by pattern 0; if negative, pattern 0 is followed by pattern 5.
shall be moved to. However, in FIG. 3, 1 indicates on and 0 indicates off. FIG. 4 is a flowchart showing this procedure.

That is, FIG. 4(a) is a flowchart showing the flow of operations when activated by the periodic interrupt signal C. Further, FIG. 4(b) is a flowchart when activated by the interrupt signal D caused by the count-up of the counter 6. Regarding interrupts, an interrupt D caused by the count up of the counter 6 has priority over a fixed period interrupt C.

As a result, the microcomputer can perform the desired ignition pulse control without performing rapid repetitive calculations, and the microcomputer can perform other calculation processing except for the time when the procedure shown in Figure 4 is being carried out. It is also possible to increase the utilization of the microcontroller.

Further, if a vector control device as a motor control device is incorporated into a microcomputer and DDC (digital direct control) is performed, data can be easily exchanged between the two.

〔Effect of the invention〕

According to the present invention, since the ignition pulse is controlled using a microcomputer, there is an advantage that the hardware configuration is simpler than that of the prior art.

In addition, the microcomputer calculates the time interval between firing pulses given to the inverter from the command values of the inverter frequency f1 and current phase angle β, and the time is counted by a counter attached outside the microcomputer, and the time generated when the count up is By determining and outputting the ignition pulse using an interrupt, the computation time necessary for the microcomputer to control the ignition pulse can be reduced, and even a microcomputer with comparatively slow arithmetic processing can perform control. The interval between processing by an interrupt and processing by the next interrupt can be used for arithmetic processing other than ignition pulse control, which has the effect of increasing the utilization of the microcomputer.

In addition, if the motor control device (vector control device) is incorporated into a microcomputer and implemented as a DDC, the D
Data can be easily exchanged between the two without going through a /A converter.

Furthermore, by using fixed period interrupts, the count setting value of the counter 6 can be corrected even in response to changes in the current phase angle command value between ignition pulses and changes in the inverter frequency command value, making it possible to adjust the control in response to changes in the command value. You can expect a quick response.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 1A is an operation waveform diagram of each part in the circuit of FIG. 1, and FIG.
2A is a time chart showing an example of the waveform of the gate control signal of each thyristor in FIG. 2, and FIG. An explanatory diagram of the firing pattern of the thyristor, FIG. 4(a) is a flowchart showing the flow of operation when activated by a fixed period interrupt signal,
FIG. 4(b) is a flowchart showing the flow of operations when activated by an interrupt signal due to count-up. Code explanation 1...Power converter (current source inverter device), 2...
・Induction motor, 3...Microcomputer, 4...Pulse amplifier, 5...Latch, 6...Counter agent Patent attorney Akio Namiki Patent attorney Kiyoshi Matsuzaki

Claims (1)

[Claims] 1) An arithmetic unit that calculates the firing pulse interval for on/off control of a semiconductor element in a power converter that supplies power to an AC motor by reading a command value given for speed control of the motor. and a counter that counts clock pulses,
and a latch for reading the count value of the counter into the arithmetic unit, and the arithmetic unit converts the firing pulse interval obtained by the calculation into the required number of the clock pulses, and uses the converted value as a setting value. set in the counter, the counter generates a first interrupt signal when it has counted the set value and inputs it to the arithmetic unit, and the arithmetic unit thereby controls the output pattern of the ignition pulse, and In an ignition pulse control method that reads the command value at that point and operates in the same manner thereafter, a second interrupt signal that is generated at a constant cycle shorter than the generation cycle of the first interrupt signal is sent to the arithmetic unit. Each time the second interrupt signal is received, the arithmetic unit reads the command value and also reads the count value of the counter at that time via the launch, and the read command value is the same as the previous command reading. ignition pulse of a semiconductor element in a power converter, characterized in that when the value is different from the value, the read count value of the counter is corrected and reset to the counter according to the difference. control method.