JPH078145B2 - Multiple pulse inverter device - Google Patents

Description

The present invention relates to a multi-pulse inverter device having a single-phase bridge inverter circuit.

"Prior Art" A multi-pulse inverter device is configured by combining a control unit with a single-phase bridge inverter circuit, and is used as a constant voltage / constant frequency device.

FIG. 2 shows an example of a multi-pulse inverter device.

The single-phase bridge inverter circuit 1 includes switching elements Q1, Q2,
Q3 and Q4 are combined in a bridge shape and diode D1,
D2, D3, D4 are connected in antiparallel to the respective switch elements, and a DC power source E is connected in parallel to the series circuit of the switch elements Q1, Q2 and the series circuit of the switch elements Q3, Q4.

A load Z and a current detector CT for detecting a load current are connected between the connection point of the switch elements Q1 and Q2 and the connection point of the switch elements Q3 and Q4, and the single phase bridge inverter circuit 1 is connected to each switch element Q1. , A combination of control units C for controlling Q2, Q3, Q4 is a multi-pulse inverter device.

FIG. 4 shows ON / OFF signals of the switch elements Q1 to Q4 that produce an output from the reference wave to the load in the conventional technique. This on / off signal is generated by the control unit.

FIG. 4 is an explanatory diagram showing operation principle waveforms of a multiple pulse inverter which compares a sine wave and a carrier triangular wave and performs a pulse width control inverter.

A signal (a) shows a full-wave rectified reference sine wave of a fundamental frequency and a carrier triangular wave of N times the fundamental frequency, and a signal (b) shows a load voltage e which is an inverter output obtained from the reference sine wave and the carrier triangular wave. And signal (c) ~
(F) is a signal waveform of the on / off operation of the switch elements Q1 to Q4 in FIG. Then, the multi-pulse inverter device supplies a load current i, which is an inverter output assuming the passage of a low-pass filter, to the load as an output.

The broadly divided sections (I) to (IV) in FIG. 4 will be described with reference to FIG. 2. When the whole is viewed in detail, the sections (I) to (IV) are zero when load voltage is generated and zero. Sometimes,
In the section (I), a subsection (V) in which the load voltage e is the positive pole and the load current i is the positive pole and a subsection (VI) in which the load voltage e is zero and the load current i is the positive pole (VI).

The load current i in the small section (V) of the section (I) returns from the DC power source E to the DC power source E through the switch element Q1, the load Z, and the switch element Q4. Similarly, in the small section (VI) of section (I),
The load current i returns from the load Z to the load Z through the switch Q4 and the diode D2.

In the next section (II), in the small section (VII) in which the load voltage e is the negative electrode and the load current i is the positive electrode, the load current i returns from the load Z to the load Z through the diode D3, the DC power supply E and the diode D2. . In the small section (VIII) where the load voltage e is zero and the load current i is positive in the section (II), the load current i is the load Z.
To the load Z through the switch element Q4 and the diode D2.

In the next section (III), in the small section (IX) in which the load voltage e is negative and the load current i is negative, the load current i passes from the DC power source E through the switch element Q3, the load Z, and the switch element Q2. Return to E. In the small section (X) where the load voltage e is zero and the load current i is negative in the section (III), the load current i is
Returns from the load Z to the load Z through the switching element Q2 and the diode D4.

In the section (IV), in the small section (XI) in which the load voltage e is positive and the load current i is negative, the load current i returns from the load Z to the load Z through the diode D1, the DC power supply E, and the diode D4. In a small section (XII) where the load voltage e is zero and the load current is negative in the section (IV), the load current i returns from the load Z to the load through the switch element Q2 and the diode D4.

"Problems to be Solved by the Invention" Considering the above-mentioned conventional technique, section (I) in FIG.
In, the turn-on of the switching element Q2 is not related to the operation of the load voltage e and the load current i. That is, switch element Q2
Does not need to be turned on in the section (I).

Further, in the section (III), turning on of the switch element Q3 is not related to the operation of the load voltage e and the load current i. That is, it is understood that the switch element Q3 does not need to be turned on in the section (III).

In the conventional single-phase bridge inverter device as described above, the switching operation of the switch element is performed in all eight operation modes depending on the polarities of the load voltage e and the load voltage i. There was a problem that a loss occurred.

An object of the present invention is to provide a multiple pulse inverter device in which the number of times of switching of a switching element is reduced and the switching loss is minimized without losing the original characteristics.

"Means for Solving the Problem" The gist of the present invention for achieving such an object is to provide two series circuits in which two switch elements are connected in series and are connected in parallel in a bridge shape. And a DC power source connected in parallel to the two series circuits and respective diodes connected to each of the switch elements in a direction in which a current flows in a reverse direction, and connecting the switch elements of the series circuit. In a multi-pulse inverter device comprising a single-phase bridge inverter circuit in which a load and a detector for detecting a load current due to the load are connected between points, and a control section for controlling the switch element is provided, a polarity determination of the load voltage is performed. And the polarity of the load current are determined, and when the polarities of the load voltage and the load current are both positive or negative, an antiparallel connection of a series circuit of two switch elements A multi-pulse inverter device characterized in that, when there is a load current flowing in each diode and a load current does not flow in each diode, the control unit is provided with a discriminating unit for outputting an ON signal of a switch element only to those not flowing. Exist in.

[Operation] The discriminating unit of the control unit discriminates the polarity of the load voltage and the polarity of the load current. When the polarities of the load voltage and the load current are both positive or negative, two switch elements are connected in series. In the circuit, the ON signal of the switch element in which the load current flows through the diode connected in anti-parallel is eliminated, and the ON signal is sent only to the other switch element.

That is, in FIG. 3, in the section (I) in which the polarities of the load voltage and the load current are both positive, the small section (V)
In the mode, the DC power source E returns to the DC power source E through the switch element Q1, the load Z, and the switch element Q4. In the small section (VI) mode, load Z to switch Q4 and diode D
Pass 2 and return to load Z.

In this section (I), the turning on of the switch element Q2 is not related to the operation of the load voltage e and the load current i, the ON signal is not sent to the switch element Q2, and the switching operation is not performed.

In the section (III) of FIG. 3 in which the polarities of the load voltage e and the load current i are both negative, in the mode of the small section (IX), the DC power is supplied from the DC power source E through the switch element Q3, the load Z, and the switch element Q2. Return to power supply E. In the mode of the small section (X), the load Z returns to the load Z through the switch element Q2 and the diode D4.

Also in this section (III), turning on of the switch element Q3 is not related to the operation of the load voltage e and the load current i. That is, the switch element Q3 does not perform the switching operation in the section (III).

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows a single-phase bridge inverter circuit 1,
The configuration is the same as the conventional one and is as described above.

FIG. 2 shows the discriminating section 10 provided in the control section C.
Zero current detection circuit 11 for detecting the load current with the current detector CT of the single-phase bridge inverter circuit 1 in the figure and determining the current polarity, oscillator 12 that oscillates the reference frequency that is the basis of the inverter output frequency, oscillator Counter 15 that divides the output to the inverter output frequency, carry triangular wave generation circuit 13 generated from oscillator 12, sine wave generation circuit 14 that matches the inverter output frequency generated from triangular wave generation circuit 13, triangular wave generation circuit 13 Comparator 16 for comparing the triangular wave of and the sine wave of the sine wave generating circuit 14 and outputting a pulse width signal, logical signal negating circuits 19, 21, 23, 24, 26, 27, logical product circuits 17, 18, 20 , 22,25,28, amplifiers 29,30,31,3 that convert logic signals to signal levels that can turn on / off switch elements
Consists of 2.

Next, the operation will be described.

Comparator and load voltage polarity discrimination signal output from counter 15
The logical product circuit 18 performs a logical operation on the pulse width signal that is the output of 16 to generate the ON / OFF signal of the switch element Q1.
The signal is amplified by the amplifier 29 and enters the switch element Q1.

The logical product circuit 25 performs a logical operation on the negative signal of the output signal of the logical product circuit 18 and the negative signal of the logical product circuit 17 in which the load voltage e and the load current i are both positive, and the switching element Q2 is turned on.
An off signal is produced, the signal is amplified by amplifier 30 and enters switch element Q2.

The negative signal of the load voltage polarity discrimination signal output from the counter 15 and the pulse width signal from the comparator 16 are logically operated by the AND circuit 20 to generate the ON / OFF signal of the switch element Q3, and the signal is amplified by the amplifier 31. Then the switch element Q3 is entered.

The negative signal of the output signal of the AND circuit 20 and the negative signal of the AND circuit 22 in which the load voltage e and the load current i are both negative are logically operated by the AND circuit 28 to turn on the switch element Q4.
An off signal is produced and the signal is amplified by amplifier 32 and enters switch element Q4.

The operation of the single-phase bridge inverter circuit 1 will be described. When both the load voltage e and the load current i have positive polarities, the DC power source E switches in the mode of the small section (V) of the section (I) in FIG. Return to the DC power source E through the element Q1, load Z, and switch element Q4. In the small section (VI) mode, the load Z returns to the load Z through the switch Q4 and the diode D2.

In this section (I), turning on of the switching element Q2 is not related to the operation of the load voltage e and the load current i. That is, the switch element Q2 does not need to be turned on in the section (I),
In this section, the amplifier 30 does not output the ON signal.

When the polarities of the load voltage e and the load current i are both negative,
In the mode of the small section (IX) of the section (III) in FIG. 4, the DC power source E returns to the DC power source E through the switch element Q3, the load Z, and the switch element Q2. In the small section (X) mode, the load Z passes from the load Z through the switch element Q2 and the diode D4.
Go back.

In this section (III), turning on of the switch element Q3 is not related to the operation of the load voltage e and the load current i. That is, the switch element Q3 does not need to be turned on in the section (III), and the amplifier 32 does not output the ON signal in this section.

"Effect of the Invention" According to the multiple pulse inverter device of the present invention, the load current is detected, and when the polarity of the load voltage and the polarity of the load current are positive polarity or negative polarity, the switching element is turned on / off. Since it is not operated, in the case of a constant voltage / constant frequency device, the load power factor is about 1.0 to 0.7 (delay) and the power factor fluctuation range is narrow, and the period in which the polarities of the load voltage and load current match is one cycle. It occupies a large part of the inside, and in this section, the dead time of the series circuit of two switch elements is not necessary, the loss due to the switch element on / off is reduced, and the efficiency is improved.

[Brief description of drawings]

1 to 3 show an embodiment of the present invention.
FIG. 4 is a block diagram of the control unit, FIG. 2 is a circuit diagram of a single-phase bridge inverter circuit, FIG. 3 is a time chart of operation waveforms, and FIG. 4 is a time chart used for explaining the operation of the conventional technique. 1 …… Single-phase bridge inverter circuit Q1 to Q4 …… Switch elements D1 to D4 …… Diode, CT …… Current detector Z …… Load, C …… Control unit 10 …… Discrimination unit 11 …… Zero current detector , 12 ・ ・ ・ Oscillator 13 …… Triangle wave generation circuit, 14 …… Sine wave generation circuit 15 …… Counter, 16 …… Comparator 17,18,20,22,25,28 …… AND circuit 19,21,23 , 24,26,27 …… Negation circuit 29〜32 …… Amplifier

Claims (1)

[Claims] 1. Two series circuits in which two switch elements are connected in series and are connected in parallel in a bridge shape,
A direct current power source connected in parallel to the two series circuits and respective diodes connected to each of the switch elements in a direction in which a current flows in a reverse direction, and between the connection points of the switch elements of the series circuit. In a multi-pulse inverter device comprising a load and a single-phase bridge inverter circuit connected to a detector for detecting a load current due to the load, and a control unit for controlling the switch element, the polarity determination of the load voltage and the load When the polarity of the current is determined and the polarities of the load voltage and the load current are both positive and negative, it is determined that the load current flows through the diodes in the antiparallel connection of the series circuit of the two switch elements and the load current does not flow. When there is a multiple pulse, the control section is provided with a discrimination section for outputting the ON signal of the switch element only to the one that does not flow. Inverter device.