JPS59175382A - Pam type inverter device - Google Patents

Abstract

PURPOSE:To reduce the size of a PAM type inverter device and to improve the reliability by memorizing the variation of a voltage control pattern in a memory circuit, thereby reducing the memory capacity of the memory circuit. CONSTITUTION:A switching element 6 is inserted to a positive potential line between a DC converter 1 and an inverter 3, and the duty ratio of the conduction and nonconduction is varied by a control signal from a controller 5'. The variation in the output voltage corresponding to the variation in the voltage control pattern, i.e., the output frequency is memorized at every pattern in a memory circuit 53' in the controller 5', the output voltage data from the memory circuit 53' is read out corresponding to the output frequency by a CPU 54', and the output voltage is controlled by altering the conducting timing of the switching element 6 by the control signal from the voltage controller 56' by the value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a PAM control inverter device that aims to reduce the memory capacity of a memory circuit that stores voltage control patterns.

[Technical background of the invention]

Conventionally, an inverter device has been used as a device for driving an AC motor. This inverter device is generally divided into two types, voltage type and current type, and FIG. 1 shows an example of the configuration of a voltage type inverter device. In the figure, 1 is a DC converter that converts an AC voltage of a commercial power supply into a DC voltage, and the DC voltage is smoothed by a smoothing capacitor 2 to obtain a DC voltage Edc. Then, the obtained DC voltage Edc is converted into an AC output voltage by an inverter 3 consisting of a first switching element such as a plurality of transistors, and the AC motor 4
supply to. In this case, by changing the conduction timing of the switching element of the inverter 3 using a control signal from the controller 5, the frequency of the AC output voltage is changed.

Now, when operating the AC motor 4 with such a voltage source inverter device, the ratio between the output voltage V and the output frequency F of the inverter 3 (hereinafter referred to as the V/'F ratio) is controlled to be approximately constant. It is desirable to operate the AC motor 4 so that its magnetic flux is approximately constant. Therefore, recently, the output frequency of the inverter device is changed by changing the conduction timing of the switching elements of the inverter 3 as described above, and the output voltage is changed by using the PwM method or PAM method.
Inverter devices that vary depending on the system have been adopted.

FIG. 2 shows an example of the main circuit configuration of a PAM type inverter device. This is to change the output voltage of the inverter device by changing the magnitude of the DC voltage Edc. As shown in the figure, a second switching element 6 such as a transistor is inserted into the positive potential line between the DC converter 1 and the inverter 3, and the duty ratio of conduction and non-conduction is determined by the controller 5'. The DC voltage gdc is changed by changing the control signal. In the figure, 71 and 72 are diodes, 8 is a smoothing reactor, and 2' is a smoothing capacitor.

On the other hand, FIG. 2(b) is a circuit diagram showing details of the controller 5'. The main controller 5' includes a setter 51' that outputs the entire output frequency command, an Al1) converter 52' that digitalizes the output frequency command, and a memory circuit SS/ that stores the V/F ratio gloss turn. , receives and receives the output frequency command, reads the V/F ratio from the memory circuit 53/ based on the output frequency command, and performs data processing.CP
U4, an output frequency control section 55' that controls the output frequency of the inverter device according to data from the CPU 4, and an output voltage control section 56/ that controls the output voltage.

Now, when operating the AC motor 4 in such a PAM type inverter device, it is preferable to keep the V/l' ratio constant as described above, but there are several types of values for the V/F ratio. If so, it is possible to improve the operating efficiency of the AC motor 4 by switching these depending on the load condition. Therefore, in a general inverter device, a plurality of types of V74 ratio patterns are prepared as shown in FIG. Conventionally, the output voltage is controlled by inputting output voltage data corresponding to each output frequency to the voltage I11! dll pattern for each V/F pattern is stored in the memory circuit 53' in the controller 5' shown in FIG. 2, and the CPU 54' reads the output voltage data from the memory circuit 53' in accordance with the output frequency. Depending on the value, the output voltage is controlled by a control signal from the voltage control section 56', exceeding the timing of conduction of the second switching element 6.

[Problems with background technology]

Incidentally, conventionally, a voltage control pattern serving as a control signal for the second switching element 6 that controls the DC voltage gdc is stored in the memory circuit 53' in the following manner. That is, if there are four types of V/F ratios as shown in FIG. 3, the memory circuit 5? As shown in Fig. 4, the storage state for ' is as follows: V/F ratio data of turn A is stored in one area, and then each of One area is provided for each turn, and the data stored in each area is, for example, the output voltage at output frequency F1.

Then, data corresponding to the size of vl is contained. Therefore, in such a storage method, there is a problem that the memory capacity of the memory circuit 53' increases in accordance with the number of V/F patterns, resulting in an increase in the size of the inverter device.

[Purpose of the invention]

The present invention has been made in order to solve the above-mentioned longevity problem, and its features 6' and 6' are: v/
It is an object of the present invention to provide a PAM type inverter device that can reduce the memory capacity of a memory circuit that stores F' ratio patterns regardless of the type of pattern, thereby reducing the size of the device.

[Summary of the invention]

In order to achieve the above object, the present invention provides a voltage side (goods) pattern when storing a voltage control nosoturn, which is a control signal of the second switching element that controls the direct current voltages E and dc, in the above-mentioned memory circuit. The change in the output voltage (V1→■2, that is, V2-V1=ΔV) corresponding to the change in the output frequency (['1→F2) of t and b is stored for each pattern. do.

[Embodiments of the invention]

Hereinafter, an embodiment of the present invention shown in the drawings will be described.

The configuration of the PAM type inverter device according to the present invention is exactly the same as that shown in FIG. 2, so a description thereof will be omitted. In other words, the PAM type inverter device of the present invention controls voltage control and turn, which is the control signal of the second switching element 6 that controls the DC voltage Ed0 mentioned above. When the data is stored in the memory circuit 53' in the memory circuit 55', the 'i@; change in the pressure control pattern is stored. That is, for example, as shown in FIG. 5, the output voltage ■1 for the output frequency Fl and the output voltage V2 for the output frequency F2.
+Similarly, if the V/F' ratio pattern is v3 for F3, Δvl=v2-v1, ΔV2=
The change in output voltage corresponding to the change in output frequency, such as V3-V2, is stored as data in the memory circuit 53' in the controller 5' in the state shown in FIG. . Although FIG. 5 only shows one type of V/F ratio pattern for convenience of explanation, in reality, the V/F ratio pattern is
As described above, a plurality of types of F ratios and patterns are prepared, and each pattern is stored in the same way.

In such a PAM type inverter device, for example, when the output voltage increases from the state of Vl at the output frequency F1 to the output frequency F2, the controller 5' increases the output voltage by Δvl based on the contents of the memory circuit 53'. A control signal is applied to the second switching element 6, and as a result, the output voltage is controlled to a value of V1+Δv1. Therefore, by controlling the output voltage by adding or subtracting the change stored in the memory circuit to the current output voltage in accordance with the change in the output frequency, the output voltage is adjusted to the open side I as in the conventional case. It turns out.

As described above, in the PAM type inverter device of the present invention, when storing the V/F' ratio/turn as a voltage control pattern in the memory circuit 5'7', the PAM type inverter device of the present invention changes the output voltage corresponding to the change in output frequency. Since the variation ΔV is stored in the memory circuit 53/, each output voltage v1 is
and to v2.

Compared to the case of absolute value storage where corresponding data is directly stored, it is possible to store several types of V/F' ratio pattern data in one word memory area, in other words, it is possible to store data with a smaller number of bits. . In other words, for example, 8-bi,
When using a 1-word memory circuit, the conventional one required one word per data to store data corresponding to voltages such as Vl and v2, but the present invention If one data can be expressed in 2 h, t, then 94 weights of data can be stored in 1 word. As a result, the memory area for storing V/F ratio patterns can be reduced to one-several types (at least half or less) compared to the conventional one, thereby saving memory capacity. In addition, since the conventional method stores the absolute value, V
/F' ratio・When changing the turn, the memory circuit 53
It is necessary to rewrite all the contents of ', but in the present invention, the lowest output frequency is F. By simply changing the value of the output voltage Vo at
/F ratio can be changed.

In the above embodiment, data of multiple types of V/F ratios and turns are stored in one word, but one type of V/F ratio and turns can be stored continuously in one word. A similar effect can be obtained even if a plurality of data are stored in the memory.

〔Effect of the invention〕

As explained above, according to the present invention, a plurality of types of V/←
The ratio P turn is stored in a memory circuit as a voltage control pattern (in a PAM type inverter device, the change in voltage control pattern (change in output voltage corresponding to change in output frequency) is stored in the memory circuit). As a result, an extremely reliable PAM type inverter device that can reduce the memory capacity of the memory circuit regardless of the v74゛ ratio/J?turn type and miniaturize the device has been created. Can be provided.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a voltage source inverter device. h” Figures 2(a), f and (b) are block diagrams showing the main circuit and controller of the PAM type in/out device, and Figure 3 is a
/F' ratio/mother turn; FIG. 4 is a diagram showing a conventional voltage control/gutter storage state; FIGS. 5 and 6 are diagrams showing an embodiment of the present invention. . 1... DC converter, 2, 2'... Smoothing capacitor,
3...Inverter, 4...AC motor, 5,5'・
...Controller, 6...Second switching element, 7th. 72...Dio-P18...Smooth reactor, 51
'... Setting device, 52'... A/D converter, 531.
...Memory circuit, 54'...CPU, 55'...Frequency control section, 56'...Voltage control section. Fig. 3 Sitting force circumference X, rice (Hz) Fig. 4 Fig. 5

Claims (1)

[Claims] a DC converter that converts an AC voltage into a DC voltage; an inverter that converts the DC voltage into an AC voltage formed from a plurality of first switching elements; 2 switching elements and a memory circuit for storing a change in the voltage control nosoturn, which is a change in the output voltage corresponding to a change in the output frequency,
Based on this voltage control/4' turn, the conduction timing of the first switching element is changed to control the output frequency of the inverter, and the conduction timing of the second switching element is changed in accordance with the output frequency. A PAM type inverter device comprising: a controller that controls the output voltage of the inverter by changing it.