JP2520305B2 - Power converter - Google Patents

Description

Description: [Industrial field of application] The present invention has an inverter main circuit in which semiconductor switching elements and the like are bridge-connected, and is applicable to a variable frequency power supply device, an uninterruptible power supply device, and the like. The present invention relates to a power converter.

[Conventional technology]

Fig. 3 shows, for example, Denshosho, published on September 7, 1985,
It is a circuit diagram which shows the conventional power converter described in "Inverter application manual" pages 39-55. In the figure, 1 is a switching element composed of a transistor T and a feedback diode D, and 2 is this switching element 1.
Inverter main circuit as a main circuit in which three pairs are connected in series to obtain an output from these connection points, and the output of the switching element pair 2 is an output for each phase and three pairs are connected in parallel. Then, a so-called three-phase half bridge inverter is configured here. Reference numeral 4 is a switching signal generating circuit as switching control means for controlling ON / OFF of each switching element 1 of the inverter main circuit 3, and reference numeral 5 is a three-phase load connected to the inverter main circuit 3.

FIG. 4 shows the internal circuit of the switching signal generating circuit 4, in which 41 is a pulse width modulation signal generating means (hereinafter referred to as PWM signal generating means), 42 is a signal inverting circuit, and 43a and 43b are both signals. Is a delay circuit for delaying the rise of the switching element, 44 is a protection circuit for stopping the driving of each switching element 1, and 45 is an AND gate.

Next, the operation will be described. First, the PWM signal generating means 41 of FIG. 4 generates signals Xu, Xv, Xw uniquely corresponding to the output voltage of each phase of U, V, W of the inverter main circuit 3. Hereinafter, since the same circuit is composed of three circuits, only the signal Xu will be described. This signal Xu is output by the inverting circuit 42.
The inverted output u of Xu is taken, and these signals Xu, u become signals whose rising edges are delayed by the on-delay circuits 43a, 43b, respectively. These signals are drive signals Sup, which control the operation of the u-phase switching element pair 2 in the normal time.
The output voltage of the inverter main circuit 3 is controlled by these drive signals Sup and Sun.

On the other hand, when it is necessary to stop the operation of the inverter main circuit 3 due to some abnormality, the protection circuit 44 generates the cutoff signal ▲ ▼, and the AND gate 45 collectively outputs all the drive signals (Sup to Swn). And turn it off.

Here, the operation of the switching signal generation circuit 4 and
The relationship with the operation of the switching element 1 of the inverter main circuit 3 will be described.

The switching element 1 composed of the transistor T and the feedback diode D, as shown in FIG.
It can be considered as one mechanical switch SM. Further, the switching element pair 2 is considered to be a three-point switch by the two mechanical switches SM shown in FIG. 5 (b). In this switching element pair 2, two switching elements 1
Although there is simultaneous ON of the inverter main circuit 3 of FIG.
In the above configuration, it is necessary to avoid a short-circuit state of the DC circuit, so that when one is on, the other is turned off so that they are not turned on at the same time. Further, the simultaneous turning off of the two switching elements 1 in each switching element pair 2 disconnects the load 5 by one phase, which is not necessary for normal operation of the three-phase inverter, and therefore, when switching each pair of switching elements 1. To prevent short circuit due to operation delay, do not perform it for an extremely short time or only when disconnecting the load by turning off all phases. Such a switching operation is executed by the configuration of the inverting circuit 42, the on-delay circuits 43a and 43b, and the AND gate 45. Therefore, the switching element pair 2 is replaced with one toggle switch ST as shown in FIG. 6 (a), and when the inverter main circuit 3 is viewed from the PWM signal generating means 41, it is shown in FIG. 6 (b). It can be considered that the switching circuit 5 shown is formed.

From this, for example, the output voltage of the u-phase becomes a positive / negative voltage based on the virtual neutral point corresponding to the signal Xu, and when considering the PWM method such as how to generate the signal Xu,
It can be treated as an extremely simple switching operation. In other words, there are four connection states that can be originally assumed as two switches, and further, only one of the two switching modes that is generated by turning on and off the other while keeping one off is limited to performing only the toggle operation. You can think about it.

[Problems to be Solved by the Invention]

Since the conventional power converter is configured as described above, it is necessary to limit the operation of the main circuit generated by the combination of ON and OFF of each switching element 1, and to operate the PWM signal generation processing by this limitation. Although the operation can be simplified in such cases as described above, in recent years, the sophistication of control by a microprocessor has advanced, and for example, in order to diversify and enhance the self-diagnosis function of a power conversion device, the above limitation causes diversification of circuit configurations. There was a problem such as blocking.

The present invention has been made to solve the above problems, and various switching modes and operations can be performed by arbitrarily selecting a switching element that constitutes an inverter main circuit and partially operating the switching element. An object is to obtain a power conversion device that can be realized.

[Means for solving the problem]

In the power conversion device according to the present invention, the switching selection control means connected to the second input terminals of the plurality of AND gates inputs the cutoff signal from the protection circuit and the element selection signal supplied from the outside. Latches the element selection signal and supplies the latched element selection signal to the AND gate connected to the switching element indicated by the element selection signal to turn off the operation of this switching element and shut it off from the protection circuit. When a signal is input,
All of the switching elements are turned off.

[Action]

A power converter according to the present invention is connected to the second input terminals of a plurality of AND gates, receives a cutoff signal from a protection circuit and an element selection signal supplied from the outside, and latches the element selection signal, This latched element selection signal is supplied to the AND gate connected to the switching element indicated by the element selection signal to turn off the operation of this switching element, and when the cutoff signal from the protection circuit is input, By providing the switching selection control means for turning off all of the switching elements,
The multi-phase inverter is operated as a single-phase half bridge for each phase, or any two phases are operated as a single-phase full-bridge inverter.

Example of Invention

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 10 is a latch circuit newly added as switching selection control means, which is connected between the protection circuit 44 and one input terminal of the AND gate 45. In addition, the same components and signals as those shown in FIG. 4 are denoted by the same reference numerals, and the duplicate description thereof will be omitted.

Next, the operation will be described. The latch circuit 10 latches element selection data output from a microprocessor (not shown), for example. Latch circuit 10 outputs Eup to Ewn
Are input to one input terminal of the AND gate 45 and gate the drive signals Sup to Swn of each switching element 1. Therefore, the output of the latch circuit 10 functions as an operation enable signal for each switching element 1 and drives the switching element 1 with a high level signal, while holding it off with a low level signal, and finally operates according to the element selection data. Specify the element to be activated.

In addition, the cutoff signal output from the protection circuit 44 ▲ ▼
Is input to the reset input terminal R of the latch circuit 10 and resets the latch circuit 10 when the cutoff signal ▲ ▼ becomes low level. As a result, all the outputs become the low level at once, all the switching elements 1 are turned off, and the operation of the inverter main circuit is stopped regardless of the element selection data. Therefore, the inverter main circuit 3 can take various forms and operations depending on the content of the element selection data output from the microprocessor or the like, as shown in FIG. 2, for example. According to this, FIGS. 2 (a) and 2 (b) show one of the u, v, and w phases on the u phase side and two switching elements 1
In FIG. 2 (c), one switching element 1 of each phase of u and v can be operated, and in FIG. 2 (d) each switching element 1 of each phase of u and v can be operated as a toggle switch as described above. The application to variable frequency power supplies, uninterruptible power supplies, and other systems can be expanded.

Although the switching selection control means 4 for controlling the three-phase transistor inverter is shown in the above embodiment, the switching element of the inverter main circuit 3 controlled by the switching selection control 4 is limited to the above-mentioned transistor or the like. Obviously not.

In addition, the conventional power converter in its normal operation,
The switching element 1 is not configured to have an unnecessary switching state and is limited to each state of the switching element 1. In contrast, the present invention removes this limitation and changes the configuration of the power conversion device. Even if the content of the restriction is different from that of the above-described embodiment, the effect that it can be widely applied to other applications can be obtained.

〔The invention's effect〕

As described above, according to the present invention, the switching selection control means connected to the second input terminals of the plurality of AND gates inputs the cutoff signal from the protection circuit and the element selection signal supplied from the outside. , This element selection signal is latched, and this latched element selection signal is supplied to the AND gate connected to the switching element indicated by this element selection signal to turn off the operation of this switching element and from the protection circuit. When the cutoff signal of is input,
Since all of the switching elements are configured to be turned off, the three-phase half bridge inverter can be operated in various forms, and such an operation can be easily performed by an extremely simple configuration, and When an abnormality occurs, it is possible to obtain something that can immediately avoid the danger.

[Brief description of drawings]

FIG. 1 is a circuit diagram of essential parts showing a power converter according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing an operation example of an inverter main circuit in the power converter of FIG. 1, and FIG. FIG. 4 is a circuit diagram showing the basic configuration of the power converter of FIG.
FIG. 5 is a circuit diagram showing the internal configuration of the switching control means in the figure, FIG. 5 is an explanatory diagram showing equivalent switching replacement states of the switching elements in FIG. 3, and FIG. 6 is an equivalent of an inverter main circuit controlled by conventional switching control means. It is explanatory drawing which shows a switch replacement state. 3 is an inverter main circuit, 4 is switching control means, 10
Is a switching selection control means (latch circuit). In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A multi-phase inverter configured by connecting a pair of switching elements in series and providing a plurality of switching element pairs so as to obtain an output from these connection points, and connecting both ends of these switching element pairs to a DC power supply. And a pulse width modulation signal generation circuit for generating a pulse width modulation signal and outputting the pulse width modulation signal to each switching element of the switching element pair, and an output terminal connected to a control terminal of each switching element, and a first input terminal connected to the above In a power converter including a plurality of AND gates to which a pulse width modulation signal is supplied and a protection circuit that outputs a cutoff signal for turning off the operation of the multi-phase inverter, the second of the plurality of AND gates is provided.
Connected to the input terminal of the protection circuit, the cutoff signal from the protection circuit and the element selection signal supplied from the outside are input, the element selection signal is latched, and the latched element selection signal is indicated by the element selection signal. Supplying to the AND gate connected to the switching element to turn off the operation of this switching element, and when a cutoff signal from the protection circuit is input, switching to turn off all of the switching elements. A power conversion device comprising a selection control means.