JPH0311187B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control circuit in a device composed of switching elements, such as an inverter or a controlled rectifier.

Conventionally, in a control circuit for a switching element that constitutes an inverter, for example, a cushion circuit is provided to prevent sudden changes when starting, stopping, or changing a set value.
Control is performed by gradually increasing or decreasing the control amount.

The cushioning time and rise (fall) rate of this cushion circuit are set by a time constant circuit including a capacitor C and a resistor R.

However, when changing the set value in this type of circuit, it is difficult to arbitrarily set the value for a short time to a long time (several μsec to several hours) in the same circuit, and the drift may be large depending on the surrounding environment, such as temperature. , the setting constants varied and did not result in the best control.

The present invention was made in view of the above circumstances, and
The purpose of this is to use a microcomputer (hereinafter referred to as μCPU) to enable arbitrary setting values to be set without changing circuit constants.
The present invention also aims to provide a control circuit with less drift.

Hereinafter, the present invention will be explained in detail based on FIGS. 1 to 6.

In Figure 1, 1 is μCPU, 1a is μCPU1
A built-in crystal oscillator, 2 is a programmable timer, and the clock signal output from the crystal oscillator 1a is
CLK is input, a preset interrupt time t ₁ is counted, and the result is output to the μCPU 1 as an interrupt signal A. This interrupt signal A is output every time t ₁ . 3 is an I/O (input/output) port, which inputs the target value V _s (amount from the initial value to the set value) from the setting section 4a of the digital setting device 4 and the cushion time t ₂ from the setting section 4b; μCPU through 10
1, input the cushion start signal S from terminal 5 and output it to μCPU1, and
A reset signal R for starting the cushion is generated by μCPU1.
is output to terminal 6. 7 is ROM, 8 is RAM,
9 is a D/A converter which converts the result calculated by μCPU 1 into an analog signal and outputs it.

FIG. 2 is a flowchart showing a program that causes the μCPU 1 to perform calculations on data input from the digital setting device 4 and stores each data in the RAM 8.

FIG. 3 is a flowchart showing a program that is activated when the interrupt signal A is input to the μCPU 1, and is activated at every interrupt time _t1 .

FIG. 4 shows a memory map diagram used in FIGS. 2 and 3.

5 and 6 are waveform diagrams of the manipulated variable V _k for the D/A converter, and the horizontal axis represents the number of interruptions k.
(k=1, 2,..., k-1, k, k+1,..., n,
[n+1]) and time T, and the vertical axis is the manipulated variable.
The subscript _k of this manipulated variable indicates the number of interruptions k, and V _k represents the manipulated variable at the time of the k-th interruption. However, k=n+1 does not mean that an interrupt is actually performed at that point, but means that the execution time _t2 has elapsed since the first interrupt (the remaining number of interrupts is zero).

Next, the operation of the device configured as described above will be explained.

Now, suppose that the digital setting section 4a sets the target value _Vs , and the setting section 4b sets the cushion time _t2 .

These setting data are input to the μCPU 1 via the I/O port 3 and the bus 10, and the program shown in FIG. 2 is started.

μCPU 1 stores the target value V _s at 21 in FIG. ₂ at location 42 of the memory map in FIG. . At 23, n=t ₂ /t ₁ At 24, the calculation ΔV _s =V _s /n is performed, and n and ΔV _s are stored at locations 44 and 45, respectively, in the memory map of FIG.

Then, the program shown in Fig. 3 is activated by the interrupt signal A generated by the timer every _t1 .
If it is determined at 31 in the figure that the cushion start signal is present, a comparison is made between the target value _Vs and the manipulated variable _Vk at 32 in FIG. Then, when V _s > V _k , perform V _k+1 = V _k + ΔV _s at 33, and when V _s < V _k , perform V _k-1 = V _k - ΔV _s at 34, and V _s = _Vk , at 37 the FLAG of the map 41 shown in FIG. 4 is cleared, and the reset signal R is output to the terminal 6 via the I/O port 3 to reset the cushion start signal.

Here, to explain FIG. 3 in the output waveform diagram shown in FIG. 5, the initial value V ₁ of the manipulated variable V _k when the first interrupt occurs is V ₁ <V _s , so At 33 in Figure 3, calculate V ₂ = V ₁ + ΔV _s ,
This V ₂ is output as the manipulated variable, and since the specified number of interrupts has not been reached, it waits for the second interrupt.

When the interrupt for each interrupt time _t1 is the kth time, it is determined at 31 that there is a cushion start signal, and at 32 the manipulated variable V _k at the time of this interrupt is compared with the target value V _s , and k=n+1 Since V _k <V _s up to 33
The manipulated variable V _k+1, which is obtained by sequentially adding ΔV _s to V _k , is output as the next manipulated variable, and at 36, there is still k
≠n+1 (that is, k<n+1), and the number of interrupts remaining is not zero, so the process ends and waits for the next interrupt.

Then, when the nth interrupt is performed,
Since the manipulated variable V _o at that point is V _o <V _s , 33
Then add ΔV _s to this manipulated variable V _o to obtain the next manipulated variable
If it is outputted as V _o+1 and 35 is replaced with k=k+1, then k=n+1 at 36, so a reset signal R is output, and at 37 the cushion signal is reset.

Also, in the output waveform diagram shown in FIG. 6, to explain FIG. 3, since V ₁ > V _s ,
At 34 in Figure 3, calculate V ₂ = V ₁ - ΔV _s , output this V ₂ as the next manipulated variable, and wait for the second interrupt since the specified number of interrupts has not been reached. .

Then, when the kth interrupt occurs every time t ₁ , 3
When it is determined that there is a cushion start signal in step 1,
At step 32, the manipulated variable V _k and the target value V _s are compared, and k=
Since V _k > V _s up to n+1, V _k
The manipulated variable V _{k+1 ,} which is obtained _by subtracting _{ΔV s} from Then subtract ΔV _s from this manipulated variable V _o to get the next manipulated variable
Output as V _o+1 . The subsequent steps are the same as those in FIG. 5 described above.

In addition, the manipulated variable V _k is transmitted through the bus 10 to the D/A
This is outputted to the converter 9, and by doing so, a stable operation amount is accurately outputted from the D/A converter 9 as a control value.

As described above, the present invention sets the cushion time t ₂ and the target value V _s and checks the magnitude of the target value V _s and the manipulated variable V _k at each predetermined interruption time t ₁ . Since the next manipulated variable V _k+1 is derived by comparing and calculating, stable control can be performed.

In other words, the precision of the coupling time is determined by the resolution of time t ₁ and ΔV _s , and the stability is determined by the temperature of the crystal oscillator 1a and changes in the power supply voltage, so it is not affected by temperature and is accurate as in the past. The manipulated variable V _k can be changed to

Further, the set amount can be changed arbitrarily without changing the hardware as in the conventional case, and adjustment can be easily performed.

For example, use a 10-turn variable resistor to set the target value.
Conventionally, when assuming 10 rotations to be 100%, the operator had to convert using a correspondence table, but the present invention has excellent advantages such as being easier to set than the digital setting device 4 and saving the time and effort of conversion. It is something that you have.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIGS. 2 and 3 are flowcharts for explaining the present invention, FIG. 4 is a memory map diagram for explaining the present invention, and FIG. 5 and 6 are waveform diagrams of manipulated variables for explaining the present invention. 1 is μCPU, 1a is crystal oscillator, 2 is programmable timer, 3 is I/O port, 4 is digital setting device, 7 is ROM, 8 is RAM, 9 is D/A
converter.

Claims (1)

[Claims] 1. In a circuit for controlling a switching element, a digital setting device for setting a target value and a cushioning time, respectively, and signals of the target value and cushioning time from each of the digital setting devices described above are inputted, respectively. The input/output port, the number of interrupts per one cushion time is obtained by dividing the above-mentioned cushion time by a preset interrupt time, and the number of interrupts per one cushion time is obtained by dividing the above-mentioned target value by the number of interrupts. a change calculation means for obtaining a change amount;
a manipulated variable calculation means that starts a program upon occurrence of the interrupt, compares the target value and the manipulated variable, and adds or subtracts the amount of change depending on whether the target value and the manipulated variable are large or small; A reset means for resetting a cushion start signal when the manipulated variables are equal, and an interrupt count monitoring means for outputting a reset signal to the reset means when the number of interrupts reaches a predetermined number of interrupts, and waiting for the next interrupt when the number of interrupts has not been reached. A control circuit for a switching element, characterized in that: