JPS62163576A - Controller for converter of pwm type - Google Patents

Abstract

PURPOSE:To set a power current waveform to be a sine wave, by computing the pulse length of PWM control pulse according to the peak value of a polyphase input waveform received from an AC power source. CONSTITUTION:By a PWM type converter, DC power is fed to a load 6 from an AC power source 1 through the main switching circuit 5 of the converter and a DC reactor 4. The controller of the converter is provided with a microcomputer 10, and is organized with a ROM 103, a RAM 104, an ALU 105 executing an arithmetic operation and the like, an event setting register 107 for setting an event necessary for generating the output of a specified pulse pattern (event), a time-setting register 108, a retaining register 109, an associative memory 110, a timer 111, a bi-time content comparing section 112, an execution controller 113, and the like. Then, pulse length is computed by the peak value of a polyphase input waveform received by the converter, and the PWM control pulse of small pulse length can be generated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a PWMIIIwj type converter,
In particular, the present invention relates to a converter control device suitable for converting an AC input waveform into a sine wave.

[Conventional technology]

Converter devices are widely used in combination with inverter devices for controlling induction motors, and in this case, it is desirable to avoid drawing distorted current from the AC power source as much as possible.

By the way, as shown in FIG. 2, for example, this converter device uses transistors (GTO having a reverse blocking function, a series connection element of a diode and a GTO or a transistor, etc.) as six rectifier elements of a three-phase full-wave rectifier circuit. (Any type of semiconductor switching element may be used) 51 to 56, and by supplying PWM control pulses to these transristors 51 to 56 to perform switching operations, the three-phase AC power source is connected to the load 6 via the DC reactor 4. It is designed to supply DC power. In addition, this FIG. 2 is an example of a current source converter, and 2 in the figure is a capacitor for overvoltage suppression.

As a PWP control device for such a converter device, for example, the paper proposed by Kibe et al., 1985 Paper 502-r Sine wave input/output current type GTO inverter system presented at the National Conference of the Institute of Electrical Engineers of Japan, was proposed by Kibe et al. As described above, a triangular carrier wave signal with a frequency sufficiently higher than the frequency of the AC power source is compared with a modulated wave signal whose peak value changes depending on the required DC side output voltage, and PWM is determined based on the magnitude relationship. Conventionally, a method of obtaining a pulse pattern for control has been common.

On the other hand, instead of such an analog system, a digital control system using a microcomputer or the like has also been proposed.

[Problem that the invention is trying to solve] However,
Of the conventional methods mentioned above, the former analog method requires a carrier wave generation circuit, a modulated wave generation circuit, a comparison circuit, etc., which not only complicates the circuit configuration, but also requires such pulse control. If the device is configured with analog circuits, there is a problem in that the characteristics change significantly due to changes in ambient temperature, aging, etc., and it is difficult to obtain stable operation.

On the other hand, even the latter digital system using a microcomputer may have adopted a square method that uses a carrier wave signal and a modulated wave signal for its operation, as in the case of the analog system described above, as in the conventional example. , computer processing is constantly tied up to compare these signals,
There is a problem that almost no other processing is possible.

In these conventional technologies, although some consideration has been given to converting the input waveform into a sine wave on the AC power supply side, the degree of achievement is not sufficient when considering variations, etc. Therefore, these conventional techniques have a problem in converting the input waveform of the converter into a sine wave.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a converter control device that can sufficiently convert an AC input into a sine wave while using a microcomputer, in order to overcome the problems of the prior art.

[Means for solving problems]

The above purpose is to calculate the pulse width of the PWM control pulse according to the peak value of the multi-phase human power waveform that the converter is about to receive from the AC power supply, and thereby to calculate the pulse width of the PWM control pulse during the computer processing time. This is accomplished by outputting PWM control pulses.

[For Ihmi]

By calculating multiple PWM control pulses during the computer processing time, it is possible to generate a sufficiently narrow PWM control pulse without increasing the computer load. It is possible to obtain sufficient wave formation.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A control device for a PWM converter according to the present invention will be explained in detail below using illustrated embodiments.

FIG. 1 shows an embodiment of the present invention, in which 1 is an AC power supply, 3 is a voltage detector that detects the power supply voltage, 5 is a main switching circuit of the converter device, 7 is a current command input terminal,
8 is a current detector, 9 is a comparator for determining current deviation, and 10 is a one-chip microcomputer for control. In addition, capacitor 2, DC reactor 4. transistor 5
The 1-56° load 6 and the like are as described above.

Microcomputer (hereinafter referred to as microcomputer) 1
0 is the manual port 101 for various commands. Internal bus 102.
RO that stores programs, pulse width data tables, etc.
MI O3, RA used as temporary memory and register
M104. An event setting register 107 that sets events necessary for outputting a predetermined pulse pattern (event) to the ALUI O5 and the output port 106 for performing calculations, etc.
Time setting register 108 for setting the time when this event is enabled. Both setting registers 107.
A holding register 109.109 concatenates and holds the contents of 108. An associative memory 110 in which several sets of setting data set in the holding register 109 are respectively stored. A comparison unit 112 that compares the timer 111 that outputs the actual time with the set time contents in the associative memory 110, and generates an output when they match. The execution controller 113 receives the trigger from the comparator 112 and controls the output of the set event to the output controller 106.

Next, the operation in this configuration will be explained using a flowchart.

In this embodiment, as shown in FIG. 3 and FIG. 5, it is composed of two large processing systems. First, FIG. 3 is a flowchart schematically illustrating a processing program F1000.

When we start processing this FlooO, we first prepare to obtain the total phase θ7 in FIloo.The zero frequency command ω,'' is the frequency value of the AC power source written in advance as data.The zero phase command θ° has the characteristics shown in Figure 4. As shown, this value is determined for the current deviation ΔiI.However, if the converter performs only pulse width control and does not use phase control together, that is, if there is no need to control the output voltage to near zero, this value should be used. You can set it to zero.

Next, this frequency command ωt is integrated every fixed time Δt1, and the phase command θ0 is subtracted to process the total phase θ process F12
Find it using 00.

Next, among the six modes in which the electrical angle 360' is divided into 60° increments, which mode should be used to output the pulse pattern for the total phase θ7 obtained this time? It is obtained by processing 1300. In addition,
The relationship between the total phase θ7 and the six modes will be explained in detail later.

Finally, the pulse pattern is changed during the interrupt interval 618, and the time t0 until the change is determined by referring to the data table with the phase θ7 is performed in the F 1400. This process causes the two registers 107 This means that the two items to be set in 108 are the event content and event change time.

Next, a process F20 of setting the two items obtained in this way in the associative memory 110 for output boat control.
00 is shown in FIG.

First, the F2100 determines whether the event settings and time settings required for the six transistors have been completed, and if NO, the F2200 performs the corresponding event settings, and the F2300
Set the event change time with and end the process.

Next, Fig. 6 shows how these two processes F1000 and F2000 are started over time.The event setting process F2000 is started in synchronization with the timer interrupt 2000 that occurs every Δ(1). On the other hand, event calculation processing F
1000 is activated by a second timer interrupt 1000 that occurs prior to timer interrupt 2000, and F 20
Complete the event calculation process before starting 00. The reason why the event calculation process F1000 is completed immediately before the event setting process F2000 is to enable the latest data to be used by F2000. Of course, if a dead time element equal to the timer interrupt interval can be included, FlooO may be performed following F2000. In that case, the time required for interrupt determination is shortened, so the interrupt interval Δ1. can be set to a short (short) value, making it possible to increase the frequency of the conversion device.

Therefore, according to this embodiment, once the predetermined event and time have been set, the associative memory section within the microcomputer takes over output boat control, so that the main processor section is freed from output processing.

Next, the determination of the pulse pattern in process F1300 will be explained using FIG.

In this embodiment, the pulse pattern is changed every 60' electrical angle, and six sets of modes that go around 360 degrees are repeated. Therefore, six sets of modes M1 to M6 having an interval of 60 degrees are selected with six total phases. The flowchart is shown in FIG. Note that the phase θ7 is O
If it appears in a region other than °~360°, perform an area check that adds or subtracts 360° and returns θ to within the region.F1
Go at the beginning of 300.

Next, in FIG. 8, the period Δt1 is specifically shown in modes M1 to M6.
This shows the following combinations: a transistor that is always turned on until an event occurs, a transistor that is turned off until an event occurs, and then turned off, and a transistor that is turned off until an event occurs and then turned on. . Therefore, if the phase θ1 is known, the mode can be known and the transistor to be turned off can be specified, and the only thing that is not known at this point (when the F1300 processing is finished) is when to turn it off. becomes. Here, ignition means specifying the output to each transistor, for example, by setting "do" in the register when setting an event, and setting "O" for extinction.

FIG. 9 describes the process (F1400 in FIG. 3) for determining the time for changing an event. In conclusion, it is sufficient to obtain a waveform close to a sine wave output, so in this embodiment, sin θ is determined according to the phase θa.

and sin with a 120° phase shift (θT−t20°)
The conductivity γ is the ratio of the peak value of Isin (θt 240°)
Δt1 is distributed to the value multiplied by 1. In other words, the first. Time until the second event occurs (changing the pulse pattern)'! In+LEt,1 is made a function of 07 and γ1 as shown in the following equation.

T! l, l=Δt, −(sin(θt 240”N・
r"Ltt, 1=Δt1・(sin θ7)・γ9 Therefore, as an example of the pulse pattern is shown in FIG. 10, when the value of this conduction rate γ" becomes small, tEIM+! Both the values of tan become smaller (Δ1.-1□1°-teh) increase, and the period during which the elements of the upper and lower arms are short-circuited becomes longer, thereby realizing a decrease in the conduction rate γ0.

This Figure 10 shows an example of the operation mode and the port output signals 551 to 356 given to the transistors 51 to 56. This occurs because the interrupt interval Δ1. is asynchronous, and in order to eliminate this, Δ1° should be set to a value that is just divisible by ω1'.

Next, FIG. 11 shows a flowchart of the event setting process, which is specific to the first part of mode 1 in this figure. Note that, as described above, although the loop configuration is described in FIG. 5 for the sake of general explanation, the process actually flows in series as shown in FIG. 11.

The flowchart in FIG. 11 starts from time t0 in FIG. 10 to t0+Δ1. This shows the event setting process for one timer interrupt period up to 100 seconds. First, when an interrupt occurs at time t0, the transistor 55 (see FIG. 8), which always fires in mode 1, and the Two sets of event sets and time sets are performed for each transistor so that a firing signal is immediately generated in the transistor 53 that is fired until the occurrence of one event. That is, an event is set so that "1" is generated in ports 3 and 5 corresponding to transistors 55 and 53, and then a predetermined time td is added to the current time t0 and set in a predetermined register as a time set. At this time, since ignition occurs immediately, it is necessary to select a value as small as possible for this time td.

As a result, the event and time are set in the associative memory 110, and thereafter, a "1" signal will be output to the transistors 55 and 53 after td has elapsed according to the schedule.

Note that the reason why the predetermined time td is added here is as follows. In other words, some time inevitably passes after an event is set in the associative memory 110 and before it is read out. , a match is no longer obtained at comparator 112, and this event is output to output port 1.
This is because it would be impossible to give it to 06.

In F2420, assuming that the operating mode has changed from the previous time due to a sudden change in the phase command θ1, etc., a process is performed to confirm the extinction of a transistor that should be in an extinguished state in this mode. The processing uses the associative memory 110 as in the F2410, but here the event is arc extinction, so "0" is written to baud) 1, 2, 4.6.
Events are set so that ′ occurs.

Next, the F 2430 performs a schedule process such that the transistor 53 is turned off at the time t0+(E1).The event is "0° output to the boat 3, and the time is 1.+j EIn
Set. If td is a certain large value,
At this point, multiple events for one output port have been scheduled at different times within the same timer interrupt.

Furthermore, F 2440 schedules the firing of transistor 51 instead of the extinguishing of transistor 53 .

Note that here, the transistor 53 is turned off and the transistor 5 is turned off.
The ignition of F2430 and F2430 were set at the same time, but in order to prevent overvoltage, the "1" period overlaps in the current source converter, and in order to create a non-lap period in the voltage type converter, the time t5 is changed between F2430 and F2430.
2440 is also possible.

Next, at the second event occurrence point "O" EXm, the transistor 51
The schedule for turning off the transistor 52 (F2450) and the schedule for turning on the transistor 52 (F2460>) are subsequently performed.

In this way, in the above embodiment, the calculation of phase θ1, θ7
The process of determining the transistor to be turned off based on , further determining the time to turn off based on θ7, and finally creating a schedule by pairing the transistor to be turned off and its time is performed every predetermined time Δt1. Therefore, through this series of processing, it is possible to compare the conventional method of comparing a carrier wave and a modulated wave with a microprocessor (
Not only is the problem that the ALU (ALU) is always restricted to comparison eliminated, but the power supply current waveform is made into a sine wave, and harmonic components do not flow into 1t'lJX, which is a great industrial advantage.

Note that the above explanation does not specifically mention synchronization with the power supply, but there is a complete synchronization process that synchronizes a series of processes repeated every Δt1 with the zero-cross signal of the power supply, and a zero-cross signal that resets Σω and Δ1°. Synchronization methods and the like are possible, but the present pulse control method is not subject to any major restrictions on these synchronization methods.

In addition, in the above explanation, a method was used that uses both pulse width control and phase control so that the output voltage can be controlled up to O, but if it is not necessary, the phase value by the phase control component is omitted when calculating the total phase θa. do it.

Furthermore, in Fig. 9, in order to downsize the table, the total phase θ is only 0° to 60°, but it is 0 to 360°.
If the phase angle θ7 is expanded to an angle of 0° to 60°, the process of converting the phase θ7 into the 0° to 60° range becomes easier.

In addition, in the schedule processing in the event setting processing F2000, the programmable 11 in the one-chip microcontroller is shown in FIG.
0 function, but if there is a shortage of ports, or if the programmable I10 in the one-chip microcontroller cannot be used due to checking the port output signal, etc., an external device with the same function can be used using the peripheral I10. Needless to say, the effects of the present invention are not impaired.

〔Effect of the invention〕

As explained above, according to the present invention, the power supply current waveform of the current source converter can be made into a sine wave, so the problems of the conventional technology can be solved, and the ideal This has the effect of realizing a converter device.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram showing one embodiment of the present invention, Fig. 2 is a circuit diagram showing an example of a current source converter device, Fig. 3 is a flowchart showing event calculation processing, and Fig. 4 is a phase/current flow diagram. FIG. 5 is a flowchart showing an example of rate characteristics; FIG. 6 is a flowchart showing event setting processing; FIG. 6 is an illustration of interrupt timing; FIG. 7 is a flowchart showing mode selection processing;
The figure is an explanatory diagram of the mode, Figure 9 is an explanatory diagram of time setting,
Figure 0 is a time chart showing an example of PWM control pulses.
FIG. 11 is a flowchart showing the event setting process. 1...AC t1i, 2...i! ! i Voltage suppression capacitor, 3... Voltage detector, 4... DC reactor, 5... Main switching circuit, 51 to 56
...Transistor, 6...Load, 7...Current command input terminal, 8...Current detector, 9...Comparator, 10...Microcomputer, 101... ...Human powered boat, 102...Internal bus, 103...ROM,
104...RAN, 105...ALU, 106
...Output port, 107...Event setting register, 10th...Time setting register, 109...Holding register, 110...Associative memory, 111...
- Timer, 112... Comparison unit, 113... Execution controller. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 too. Figure 8 Figure 9 Figure 1O (M6+MI +M2+M3÷y4+M5)
-4-tvte'-4-tvyt 1st/Fig.

Claims (1)

[Scope of Claims] 1. Control of a converter in which a control command is taken in at a predetermined approximately constant cycle to generate a PWM control pulse for a main switching element of a converter that converts multiphase AC power into DC power. In the apparatus, means is provided for calculating the pulse width of the PWM control pulse according to the peak values of the voltages of at least two phases of the polyphase alternating current appearing at the input of the converter, and the pulse width of the PWM control pulse is 1. A control device for a PWM type converter, characterized in that it is configured to generate a PWM control pulse of. 2. In claim 1, the control command is:
P characterized in that it includes, as one component, a phase command obtained by integrating data corresponding to the frequency of the multiphase AC power supply at each predetermined substantially constant period.
Control device for WM type converter. 3. In claim 1, the control command is:
A control device for a PWM type converter, characterized in that it includes, as one component, a phase command obtained in response to a deviation between a current command for the converter and an output current of the converter.