JPH10309081A - Control method for cycloconverter frequency link inverter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply a connected load with a sine wave even when the polarity is different between the input voltage and the output voltage by employing a power supply rectifier system when the output current and the output voltage have a same polarity otherwise employing a natural rectifier system. SOLUTION: In the case of a lagging load 7 having an inductance component, one period of the basic wave of output voltage V0 and the input current IL of an output filter is divided into four intervals. A power supply rectifier system relying upon zero switching(ZCS) is employed for the interval where the input current IL of the output filter, the output current I0 and the output voltage V0 of an inverter have the same polarity. A natural rectifier system is employed for the interval where the input current IL of the output filter, the output current I0 and the output voltage V0 of the inverter have different polarities.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method of a cycloconverter type high frequency link inverter for converting DC power into AC power.

[0002]

2. Description of the Related Art FIG. 1 shows the configuration of a cycloconverter type high frequency link inverter. In the figure, 1 is a cycloconverter type high frequency link inverter, 2 is a DC power supply, 3
Is a high frequency inverter, 4 is a high frequency transformer, 5 is a cyclo converter, 6 is an output filter, 7 is a load, S +, S
-, SU +, SL +, SU-, SL- are semiconductor switches, DS +,
DS-, DSU +, DSL +, DSU- and DSL- are diodes. The both ends of the high frequency transformer 4 are Vtr, the output voltage of the cycloconverter 5 is Vc, the output voltage and current of the cycloconverter type high frequency link inverter are Vo and Io, and the input current of the output filter is IL. Vtr, Vc
, Vo, Io and IL have the positive polarity shown in FIG. Note that the direction of the current that can be passed through each semiconductor switch is opposite to the direction of the current that can be passed through the diode connected in parallel with each semiconductor switch. Also, semiconductor switches S +, S
-, SU +, SL +, SU-, and SL- are, for example, IGB
T (InsulatedGate Bipolar T
transcriptor, MOSFET, bipolar transistor, etc., and IGBT or MOSFE.
When using T, parasitic diodes of IGBT and MOSFET are replaced with diodes DS +, DS-, DSU +, DSL +,
DSU- and DSL- can be substituted.

FIG. 2 shows the relationship between the output voltage Vo of the cycloconverter type high frequency link inverter 1 and the input current IL of the output filter when 7 is a pure resistance load. One cycle of the fundamental wave of the output voltage Vo and the input current IL of the output filter is divided into two periods A and B depending on the polarity of the output voltage Vo and the input current IL of the output filter.

FIGS. 10, 11, 13 and 14 show the control methods of the conventional cycloconverter type high frequency link inverter in the period A and the period B, respectively. In the figure,
The bold line is the current path. FIGS. 12 and 15 show the waveform of each part and the drive signal of each semiconductor switch in the period A and the period B, respectively.

In the periods A and B, the switches S + and S- of the high-frequency inverter are driven by a signal based on a PWM signal obtained by comparing a sawtooth wave and a sine wave. Only the switch that can pass the output current is kept on.

First, a control method of a conventional cycloconverter type high frequency link inverter in a period A is shown in FIG.
0, FIG. 11, and FIG. Condition A-
At 1, S +, SU +, and SL + are on, and S-, SU-,
SL- is off. On the primary side of the high-frequency transformer 4, the DC power supply 2, the high-frequency transformer 4, S +, the DC power supply 2
A current flows through the path, and the transformer primary side voltage Vtr has a positive polarity. On the secondary side of the high-frequency transformer 4, a current flows through a path of the high-frequency transformer 4, SU +, DSU +, the reactor of the output filter 6, the load 7, and the high-frequency transformer 4. The cycloconverter output voltage Vc has a positive polarity.
By turning off S + from this state, a transition is made to state A-2.

In state A-2, SU + and SL + are on,
S +, S-, SU- and SL- are off. Transformer 1
The secondary-side voltage Vtr becomes negative due to the back electromotive force of the high-frequency transformer 4, and a current flows on the primary side of the high-frequency transformer 4 through a path including the DC power supply 2, DS−, the high-frequency transformer 4, and the DC power supply 2. On the secondary side of the high-frequency transformer 4, the current flowing through the high-frequency transformer 4, SU +, DSU +, the reactor of the output filter 6, the load 7, and the high-frequency transformer 4 decreases, and the high-frequency transformers 4, SL +, DSL +, and the output filter The current that has begun to flow through the reactor 6, load 7, and high-frequency transformer 4 increases. The cycloconverter output voltage Vc is zero. From this state, the current flowing through the path of the DC power supply 2, DS-, the high-frequency transformer 4, and the DC power supply 2 on the primary side of the high-frequency transformer 4 becomes zero,
When the currents flowing through the secondary side of the high-frequency transformer 4 on SU + and SL + become equal, the state transits to the state A-3.

In state A-3, SU + and SL + are on, and S +, S-, SU-, and SL- are off. No current flows on the primary side of the high-frequency transformer 4, and the transformer primary-side voltage Vtr is zero. On the secondary side of the high-frequency transformer 4, the high-frequency transformer 4, SU +, DSU +, and the output filter 6
, The load 7, the high-frequency transformer 4, the high-frequency transformer 4, SL +, DSL +, and the output filter 6.
A current having the same current value flows through the reactor, the load 7 and the high-frequency transformer 4. The cycloconverter output voltage Vc is zero. By turning on S- from this state, the state shifts to state A-4.

In state A-4, S-, SU +, and SL + are on, and S +, SU-, and SL- are off. On the primary side of the high-frequency transformer 4, the DC power supply 2, the high-frequency transformer 4,
Current flows through the path of S-, DC power supply 2 and transformer 1
The secondary voltage Vtr has a negative polarity. On the secondary side of the high-frequency transformer 4, the current flowing through the high-frequency transformer 4, SU +, DSU +, the reactor of the output filter 6, the load 7, and the high-frequency transformer 4 decreases, and the high-frequency transformers 4, SL
+, DSL +, the reactor of the output filter 6, the load 7, and the current flowing through the path of the high-frequency transformer 4 increase. The cycloconverter output voltage Vc is zero. From this state, all the current flowing to SU + moves to the SL + side, and SU +
When the current flowing through becomes zero and Vc becomes positive, the state shifts to state A-5.

In the state A-5, S-, SU +, and SL + are on, and S +, SU-, and SL- are off. On the primary side of the high-frequency transformer 4, a current flows through a path including the DC power supply 2, the high-frequency transformer 4, S−, and the DC power supply 2, and the transformer primary-side voltage Vtr has a negative polarity. On the secondary side of the high-frequency transformer 4, a current flows through a path of the high-frequency transformer 4, SL +, DSL +, the reactor of the output filter 6, the load 7, and the high-frequency transformer 4. Cycloconverter output voltage V
c is positive polarity. By turning off S- from this state, the state shifts to state A-6.

In a state A-6, SU + and SL + are on, and S +, S-, SU- and SL- are off. The transformer primary-side voltage Vtr becomes positive due to the back electromotive force of the high-frequency transformer 4, and a current flows through the primary side of the high-frequency transformer 4 through a path including the DC power supply 2, DS +, the high-frequency transformer 4, and the DC power supply 2. On the secondary side of the high-frequency transformer 4, the current that starts flowing through the high-frequency transformer 4, SU +, DSU +, the reactor of the output filter 6, the load 7, and the high-frequency transformer 4 increases, and the high-frequency transformer 4, SL +, DSL +, and the output filter 6 reactor, load 7, high frequency transformer 4
The current flowing through the path decreases. The cycloconverter output voltage Vc is zero. From this state, the current flowing through the path of the DC power supply 2, DS +, the high-frequency transformer 4, and the DC power supply 2 on the primary side of the high-frequency transformer 4 becomes 0, and the current flowing through the secondary side of the high-frequency transformer 4 through SU + and SL + When the values of E are equal, the state shifts to state A-7.

In a state A-7, SU + and SL + are on, and S +, S-, SU- and SL- are off. No current flows on the primary side of the high-frequency transformer 4, and the transformer primary-side voltage Vtr is zero. On the secondary side of the high-frequency transformer 4, the high-frequency transformer 4, SU +, DSU +, and the output filter 6
, The load 7, the high-frequency transformer 4, the high-frequency transformer 4, SL +, DSL +, and the output filter 6.
A current having the same current value flows through the reactor, the load 7 and the high-frequency transformer 4. The cycloconverter output voltage Vc is zero. Turning on S + from this state causes a transition to state A-8.

In state A-8, S +, SU +, and SL + are on, and S-, SU-, and SL- are off. On the primary side of the high-frequency transformer 4, the DC power supply 2, the high-frequency transformer 4,
The current flows through the path of S + and DC power supply 2 and the transformer 1
The secondary voltage Vtr has a positive polarity. High frequency transformer 4-2
On the secondary side, the current flowing through the path of the high-frequency transformer 4, SU +, DSL +, the reactor of the output filter 6, the load 7, and the high-frequency transformer 4 increases, and the high-frequency transformer 4, S +
The current flowing through the path of L +, DSL +, the reactor of the output filter 6, the load 7, and the high-frequency transformer 4 decreases. The cycloconverter output voltage Vc is zero. From this state, all the current flowing to SL + moves to the SU + side, and SL +
When the current flowing through becomes zero and Vc becomes positive, the state shifts to state A-1.

As described above, in the period A, the states A-1 to A-8 are sequentially repeated. A control method of the conventional high frequency link inverter of the cycloconverter type during the period B will be described with reference to FIGS. 13, 14, and 15. FIG.

In the state B-1, S-, SU-, and SL- are on, and S +, SU +, and SL + are off. On the primary side of the high-frequency transformer 4, a current flows through a path including the DC power supply 2, the high-frequency transformer 4, S−, and the DC power supply 2, and the transformer primary-side voltage Vtr has a negative polarity. On the secondary side of the high-frequency transformer 4, a current flows through the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SU−, DSU− and the high-frequency transformer 4. Cycloconverter output voltage V
c is negative polarity. By turning off S- from this state, the state shifts to state B-2.

In the state B-2, SU- and SL- are on, and S +, S-, SU +, and SL + are off. The transformer primary-side voltage Vtr becomes positive due to the back electromotive force of the high-frequency transformer 4, and a current flows through the primary side of the high-frequency transformer 4 through a path including the DC power supply 2, DS +, the high-frequency transformer 4, and the DC power supply 2. On the secondary side of the high-frequency transformer 4, the high-frequency transformer 4, the load 7, the reactor of the output filter 6,
The current flowing in the path of SU-, DSU- and high-frequency transformer 4 decreases, and the high-frequency transformer 4, load 7, reactor of output filter 6, SL-, DSL-, high-frequency transformer 4
The current that has begun to flow along the path increases. The cycloconverter output voltage Vc is zero. From this state, the current flowing through the path of the DC power supply 2, DS +, the high-frequency transformer 4, and the DC power supply 2 on the primary side of the high-frequency transformer 4 becomes zero, and the current flows to SU- and SL- on the secondary side of the high-frequency transformer 4. When the values of the flowing currents become equal, a transition is made to the state B-3.

In state B-3, SU- and SL- are on, and S +, S-, SU +, and SL + are off. No current flows on the primary side of the high-frequency transformer 4, and the transformer primary-side voltage Vtr is zero. On the secondary side of the high-frequency transformer 4, a path of the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SU−, DSU− and the high-frequency transformer 4, and the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SL− , DSL-, and the high-frequency transformer 4 flow currents having the same current value. The cycloconverter output voltage Vc is zero. Turning on S + from this state causes a transition to state B-4.

In state B-4, S +, SU-, and SL- are on, and S-, SU +, and SL + are off. On the primary side of the high-frequency transformer 4, a current flows through a path including the DC power supply 2, the high-frequency transformer 4, S +, and the DC power supply 2, and the transformer primary-side voltage Vtr has a positive polarity. On the secondary side of the high-frequency transformer 4, the current flowing through the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SU−, DSU− and the high-frequency transformer 4 decreases, and the high-frequency transformer 4,
Load 7, reactor of output filter 6, SL-, DSL-,
The current flowing through the high-frequency transformer 4 increases. The cycloconverter output voltage Vc is zero. From this state, all the current flowing to SU- moves to the SL- side, and SU-
When the current flowing through becomes zero and Vc becomes negative, the state shifts to state B-5.

In state B-5, S +, SU-, and SL- are on, and S-, SU +, and SL + are off. On the primary side of the high-frequency transformer 4, a current flows through a path including the DC power supply 2, the high-frequency transformer 4, S +, and the DC power supply 2, and the transformer primary-side voltage Vtr has a positive polarity. On the secondary side of the high-frequency transformer 4, a current flows through the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SL−, DSL−, and the high-frequency transformer 4. Cycloconverter output voltage V
c is negative polarity. By turning off S + from this state, the state shifts to state B-6.

In state B-6, SU- and SL- are on, and S +, S-, SU +, and SL + are off. The transformer primary side voltage Vtr becomes negative due to the back electromotive force of the high-frequency transformer 4, and a current flows through the primary side of the high-frequency transformer 4 through a path of the DC power supply 2, DS−, the high-frequency transformer 4, and the DC power supply 2. On the secondary side of the high-frequency transformer 4, the high-frequency transformer 4, the load 7, the reactor of the output filter 6,
The current that has started flowing through the path of SU-, DSU-, and high-frequency transformer 4 increases, and the high-frequency transformer 4, the load 7, the reactor of the output filter 6, the SL-, DSL-, and the high-frequency transformer 4
The current flowing through the path decreases. The cycloconverter output voltage Vc is zero. From this state, the current flowing through the path of the DC power supply 2, DS-, the high-frequency transformer 4, and the DC power supply 2 on the primary side of the high-frequency transformer 4 becomes 0, and SU- and SL- When the values of the currents flowing through become equal, the state shifts to state B-7.

In state B-7, SU- and SL- are on, and S +, S-, SU +, and SL + are off. No current flows on the primary side of the high-frequency transformer 4, and the transformer primary-side voltage Vtr is zero. On the secondary side of the high-frequency transformer 4, a path of the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SU−, DSU− and the high-frequency transformer 4, and the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SL− , DSL-, and the high-frequency transformer 4 flow currents having the same current value. The cycloconverter output voltage Vc is zero. From this state, the state shifts to state B-8 by turning on S-.

In the state B-8, S-, SU-, and SL- are on, and S +, SU +, and SL + are off. On the primary side of the high-frequency transformer 4, a current flows through a path of the DC power supply 2, the high-frequency transformer 4, S-, and the DC power supply 2, and the transformer primary-side voltage Vtr becomes negative. On the secondary side of the high-frequency transformer 4, the current flowing through the path of the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SU−, DSU− and the high-frequency transformer 4 increases.
Load 7, reactor of output filter 6, SL-, DSL-,
The current flowing through the high-frequency transformer 4 decreases. The cycloconverter output voltage Vc is zero. From this state, all the current flowing to SL- moves to the SU- side,
When the current flowing through L- becomes zero and Vc becomes negative, the state shifts to state B-1. As described above, in the period B, the states B-1 to B-8 are sequentially repeated.

[0023]

In the above-described control method of the cycloconverter type high frequency link inverter, the load has an inductance component and a capacitance component,
If the polarity of the input current and the output voltage of the output filter are different, in the high-frequency inverter, not the switch but the diode conducts, so that the switch of the high-frequency inverter cannot control the current flow path. Therefore, when the polarities of the input current and the output voltage of the output filter are different, an output obtained by amplifying the PWM signal cannot be generated by the high-frequency inverter, and a sine wave cannot be output to the load.

The present invention has been made in view of such a problem, and an object of the present invention is to connect a load having an inductance or a capacitor component, so that the input current and the output voltage of the output filter have different polarities. In such a case, a sine wave is output to a load connected to a cycloconverter type high frequency link inverter.

[0025]

In order to achieve the above object, a control method of a cycloconverter type high frequency link inverter according to the present invention has a power supply commutation method and a different polarity when an output current and an output voltage have the same polarity. In some cases, a natural commutation method is used.

Further, in the control method of the high frequency link inverter of the cycloconverter type according to the present invention, a high frequency inverter connected to an output terminal of a DC power supply and alternately outputting positive and negative polarities is connected to an output terminal of the high frequency inverter via a high frequency transformer. A cycloconverter system in which the output polarity of the high-frequency inverter is switched to thereby connect a cycloconverter that converts the output frequency of the high-frequency inverter to an alternating current having a lower frequency than the output frequency of the high-frequency inverter and an output filter that reduces high-frequency ripples at the output of the cycloconverter. In the high-frequency link inverter, when the output voltage of the cycloconverter type high-frequency link inverter and the polarity of the input current of the output filter are different, the high-frequency inverter power-amplifies a pulse signal having a constant duty ratio and alternates between the positive and negative polarities. Frequency transformer to output a voltage,
When the voltage of the DC power supply is applied to the high-frequency transformer, the output current of the cyclo-converter high-frequency link inverter can flow, and the semiconductor switch of the cyclo-converter that can increase the output current is turned on. The polarity of the output voltage of the high-frequency inverter is inverted, and after a certain period of time, the output current of the cycloconverter-type high-frequency link inverter can flow and the output current of the cycloconverter can be increased. By turning on, the output current flows to the semiconductor switch, and the current flowing to the semiconductor switch that was turned on before the output polarity of the high-frequency inverter is inverted becomes zero.
The semiconductor switch is turned off before the polarity of the output voltage of the high frequency inverter is inverted.

The control method of the cycloconverter type high frequency link inverter according to the present invention is the control method of the cycloconverter type high frequency link inverter described above.
PWM (Pulse Width Modulatio)
n) The switch of the cycloconverter is controlled by a signal.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows the configuration of a cycloconverter type high frequency link inverter. In the figure, 1 is a cycloconverter type high frequency link inverter, 2 is a DC power supply, 3 is a high frequency inverter, 4 is a high frequency transformer, 5 is a cycloconverter, 6 is an output filter, 7 is a load, S +, S-, SU +, and SL +. , SU-, SL- are semiconductor switches, DS +, DS-, DSU +, DSL +, DSU-, DSL-
Is a diode. The voltage across the high frequency transformer 4 is Vtr, the output voltage of the cycloconverter 5 is Vc, the output voltage and current of the cycloconverter type high frequency link inverter are Vo and Io, and the input current of the output filter is IL.
And The polarities of Vtr, Vc, Vo, Io and IL have the positive polarity shown in FIG. Note that the direction of the current that can be passed through each semiconductor switch is opposite to the direction of the current that can be passed through the diode connected in parallel with each semiconductor switch. As the semiconductor switches S +, S-, SU +, SL +, SU-, and SL-, for example, IGBTs, MOSFETs, bipolar transistors, and the like can be used. When IGBTs and MOSFETs are used, IGBTs and MOSFETs can be used. Of the diode DS +, DS-, DSU +, DSL +, DSU-
, DSL-.

FIG. 3 shows the relationship between the output voltage Vo of the cycloconverter type high frequency link inverter 1 and the input current IL of the output filter when the load 7 is a delay load having an inductance component. One cycle of the fundamental wave of the output voltage Vo and the input current IL of the output filter is divided into four periods from period 1 to period 4 depending on the polarity of the output voltage Vo and the input current IL of the output filter.

In the periods 1 and 3, the switches S + and S- of the high-frequency inverter are driven by a signal based on the PWM signal, and only the switch of the cycloconverter that keeps the output current flowing is kept on. In periods 2 and 4, the high frequency inverter switches S + and S +
Is driven by a signal having a constant duty ratio, and the switches SU +, SL +, SU-, and SL- of the cycloconverter are driven by a signal based on the PWM signal.

A control circuit (not shown) detects the current IL flowing through the output filter and the output voltage Vo, and outputs 1 when the polarities are the same and 0 when the polarities are different using a logic circuit. When it is 1, a switch drive signal for controlling period 1 and period 3 is output, and when it is 0, a switch drive signal for controlling period 2 and period 4 is output.

Period 1 and Period 3 are respectively [Prior art]
Performs the circuit operation corresponding to the periods A and B in. 4 and 5 are state transition diagrams of the cyclo-converter type high frequency link inverter of the present embodiment in period 2, and FIG. 6 is a waveform of each part and a drive signal of each semiconductor switch in period 2. 7 and 8 are state transition diagrams of the cycloconverter of the present embodiment in period 4, and FIG. 9 shows waveforms of respective parts and drive signals of the semiconductor switches in period 4.

Next, a control method of the cycloconverter type high frequency link inverter of the present embodiment during the period II will be described with reference to FIGS. 4, 5 and 6. In the state 2-1, S + and SL + are on, and S-, SU + and SU
-, SL- are off. On the primary side of the high-frequency transformer 4, a current flows through a path including the DC power supply 2, DS +, the high-frequency transformer 4, and the DC power supply 2, and the transformer primary-side voltage Vtr has a positive polarity. On the secondary side of the high-frequency transformer 4, a current flows through a path of the high-frequency transformer 4, SL +, DSL +, the reactor of the output filter 6, the load 7, and the high-frequency transformer 4. The cycloconverter output voltage Vc has a negative polarity.
By turning on SU + when the PWM signal rises from this state, the state shifts to state 2-2.

In the state 2-2, S +, SU +, and SL + are on, and S-, SU-, and SL- are off. On the primary side of the high-frequency transformer 4, the current flowing through the path of the DC power supply 2, DS +, the high-frequency transformer 4, and the DC power supply 2 decreases, the current flowing to DS + becomes 0, and the current flowing direction is reversed. , DC power supply 2, high-frequency transformer 4, S +,
A current flows through a path of the DC power supply 2. The transformer primary side voltage Vtr has a positive polarity. On the secondary side of the high-frequency transformer 4, the high-frequency transformer 4, SU +, DSU +, and the output filter 6
The current that has begun to flow through the reactor, load 7, and high-frequency transformer 4 increases, and the high-frequency transformer 4, SL +, D
The current flowing through the path of SL +, the reactor of the output filter 6, the load 7, and the high-frequency transformer 4 decreases. The cycloconverter output voltage Vc is zero. From this state, on the secondary side of the high-frequency transformer 4, the high-frequency transformer 4, SL +,
The current flowing in the path of DSL +, the reactor of the output filter 6, the load 7, and the high-frequency transformer 4 becomes 0, and the state shifts to the state 2-3 when Vc becomes positive.

In state 2-3, S +, SU +, and SL + are on, and S-, SU-, and SL- are off. On the primary side of the high-frequency transformer 4, the DC power supply 2, the high-frequency transformer 4,
The current flows through the path of S +, DC power supply 2 and the transformer 1
The secondary voltage Vtr has a positive polarity. On the secondary side of the high-frequency transformer 4, a current flows through a path of the high-frequency transformer 4, SU +, DSU +, the reactor of the output filter 6, the load 7, and the high-frequency transformer 4. High frequency transformer 4, SL +, DSL +,
No current flows through the path of the reactor of the output filter 6, the load 7, and the high-frequency transformer 4. The cycloconverter output voltage Vc has a positive polarity. By turning off the SL + switch when the current is 0, switching is performed without generating a switching surge, which is an excessive voltage generated at both ends of the switch due to the leakage inductance of the transformer.
By turning off the switch of SL + in this way, the state 2
Move to -4.

In state 2-4, S + and SU + are on,
S-, SL +, SU-, and SL- are off. On the primary side of the high-frequency transformer 4, the DC power supply 2, the high-frequency transformer 4,
The current flows through the path of S +, DC power supply 2 and the transformer 1
The secondary voltage Vtr has a positive polarity. On the secondary side of the high-frequency transformer 4, a current flows through a path of the high-frequency transformer 4, SU +, DSU +, the reactor of the output filter 6, the load 7, and the high-frequency transformer 4. The cycloconverter output voltage Vc has a positive polarity. By turning off the switch of S + from this state, the state shifts to state 2-5.

In state 2-5, SU + is on and S +,
S-, SL +, SU-, and SL- are off. Transformer 1
The polarity of the secondary side voltage Vtr is inverted by the back electromotive force because S + is cut off, and becomes negative. On the primary side of the high-frequency transformer 4,
A current flows through a path of the DC power supply 2, DS-, the high-frequency transformer 4, and the DC power supply 2. On the secondary side of the high-frequency transformer 4, the high-frequency transformer 4, SU +, DSU +, and the output filter 6
A current flows through the reactor, the load 7 and the high-frequency transformer 4. The cycloconverter output voltage Vc has a negative polarity. By turning on the switch S- from this state, the state shifts to the state 2-6.

In state 2-6, S- and SU + are on, and
S +, SL +, SU-, and SL- are off. On the primary side of the high-frequency transformer 4, a current flows through a path of the DC power supply 2, DS-, the high-frequency transformer 4, and the DC power supply 2, and the transformer 1
The secondary voltage Vtr has a negative polarity. On the secondary side of the high-frequency transformer 4, a current flows through a path of the high-frequency transformer 4, SU +, DSU +, the reactor of the output filter 6, the load 7, and the high-frequency transformer 4. The cycloconverter output voltage Vc has a negative polarity. By turning on SL + when the PWM signal rises from this state, the state shifts to state 2-7.

In the state 2-7, S-, SU +, and SL + are on, and S +, SU-, and SL- are off. On the primary side of the high-frequency transformer 4, the current flowing through the path of the DC power supply 2, DS-, the high-frequency transformer 4, and the DC power supply 2 decreases, the current flowing through DS- becomes zero, and the direction in which the current flows further decreases. Invert, high frequency transformer 4, S-, DC power supply 2,
A current flows through a path called the high-frequency transformer 4. The transformer primary side voltage Vtr has a negative polarity. High frequency transformer 4-2
On the secondary side, the current that has started flowing through the path of the high-frequency transformer 4, SL +, DSL +, the reactor of the output filter 6, the load 7, and the high-frequency transformer 4 increases.
The current flowing through the path of U +, DSU +, the reactor of the output filter 6, the load 7, and the high-frequency transformer 4 decreases. The cycloconverter output voltage Vc is zero. From this state, on the secondary side of the high-frequency transformer 4, the high-frequency transformer 4,
SU +, DSU +, reactor of output filter 6, load 7,
The current flowing through the high-frequency transformer 4 becomes zero,
When Vc becomes positive, the state shifts to state 2-8.

In the state 2-8, S-, SU +, and SL + are on, and S +, SU-, and SL- are off. On the primary side of the high-frequency transformer 4, the DC power supply 2, the high-frequency transformer 4,
Current flows through the path of S-, DC power supply 2 and transformer 1
The secondary voltage Vtr has a negative polarity. On the secondary side of the high-frequency transformer 4, a current flows through a path of the high-frequency transformer 4, SL +, DSL +, the reactor of the output filter 6, the load 7, and the high-frequency transformer 4. High frequency transformer 4, SU +, DSU +,
No current flows through the path of the reactor of the output filter 6, the load 7, and the high-frequency transformer 4. The cycloconverter output voltage Vc has a positive polarity. By turning off the SU + switch when the current is 0, switching is performed without generating a switching surge, which is an excessive voltage generated at both ends of the switch due to the leakage inductance of the transformer.
By turning off the SU + switch in this way, state 2
Move to -9.

In state 2-9, S- and SL + are on,
S +, SU +, SU-, and SL- are off. On the primary side of the high-frequency transformer 4, the DC power supply 2, the high-frequency transformer 4,
Current flows through the path of S-, DC power supply 2 and transformer 1
The secondary voltage Vtr has a negative polarity. On the secondary side of the high-frequency transformer 4, a current flows through a path of the high-frequency transformer 4, SL +, DSL +, the reactor of the output filter 6, the load 7, and the high-frequency transformer 4. The cycloconverter output voltage Vc has a positive polarity. By turning off the switch S- from this state, the state shifts to state 2-10.

In state 2-10, SL + is on and S +
, S−, SU +, SU−, and SL− are off. The polarity of the transformer primary side voltage Vtr is inverted by the back electromotive force because S- is cut off, and becomes positive. On the primary side of the high-frequency transformer 4, the DC power supply 2, DS +, the high-frequency transformer 4, the DC power supply 2
The current flows through the path. On the secondary side of the high-frequency transformer 4, a current flows through a path of the high-frequency transformer 4, SL +, DSL +, the reactor of the output filter 6, the load 7, and the high-frequency transformer 4. The cycloconverter output voltage Vc has a negative polarity. When the switch of S + is turned on from this state, the state shifts to state 2-1.

As described above, in the period 2, the states 2-1 to 2-10 are sequentially repeated. Next, the commutation method of the cycloconverter of the present embodiment in period 4 will be described with reference to FIGS.
This will be described with reference to FIG.

In state 4-1, S- and SL- are on, and
S +, SU +, SL +, and SU- are off. On the primary side of the high-frequency transformer 4, a current flows through a path of the DC power supply 2, DS-, the high-frequency transformer 4, and the DC power supply 2, and the transformer 1
The secondary voltage Vtr has a negative polarity. On the secondary side of the high-frequency transformer 4, a current flows through the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SL−, DSL−, and the high-frequency transformer 4. The cycloconverter output voltage Vc has a positive polarity. By turning on SU- when the PWM signal rises from this state, the state shifts to state 4-2.

In the state 4-2, S-, SU-, and SL- are on, and S +, SU +, and SL + are off. On the primary side of the high-frequency transformer 4, the current flowing through the path of the DC power supply 2, DS-, the high-frequency transformer 4, and the DC power supply 2 decreases, the current flowing through DS- becomes zero, and the direction in which the current flows further decreases. Invert, DC power supply 2, S-, high frequency transformer 4,
A current flows through a path of the DC power supply 2. The transformer primary side voltage Vtr has a negative polarity. On the secondary side of the high-frequency transformer 4, the current that has started flowing through the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SU-, DSU-, and the high-frequency transformer 4 increases, and the high-frequency transformer 4, the load 7,
The current flowing through the reactor of the output filter 6, SL-, DSL-, and the high-frequency transformer 4 decreases. The cycloconverter output voltage Vc is zero. From this state, on the secondary side of the high-frequency transformer 4, the current flowing through the high-frequency transformer 4, the load 7, the reactor of the output filter 6, the SL-, DSL-, and the high-frequency transformer 4 becomes zero, and Vc
The state shifts to the state 4-3 by becoming negative.

In state 4-3, S-, SU-, and SL- are on, and S +, SU +, and SL + are off. On the primary side of the high-frequency transformer 4, the DC power supply 2, the high-frequency transformer 4,
Current flows through the path of S-, DC power supply 2 and transformer 1
The secondary voltage Vtr has a negative polarity. On the secondary side of the high-frequency transformer 4, a current flows through the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SU−, DSU− and the high-frequency transformer 4. No current flows through the path of the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SL-, DSL-, and the high-frequency transformer 4. The cycloconverter output voltage Vc has a negative polarity. By turning off the switch of SL- when the current is 0, switching is performed without generating a switching surge, which is an excessive voltage generated at both ends of the switch due to leakage inductance of the transformer.
By turning off the switch of SL- in this way, state 4
Move to -4.

In state 4-4, S- and SU- are on, and
S +, SU +, SL +, and SL- are off. On the primary side of the high-frequency transformer 4, the DC power supply 2, the high-frequency transformer 4,
Current flows through the path of S-, DC power supply 2 and transformer 1
The secondary voltage Vtr has a negative polarity. On the secondary side of the high-frequency transformer 4, a current flows through the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SU−, DSU− and the high-frequency transformer 4. The cycloconverter output voltage Vc has a negative polarity. By turning off the switch S- from this state, the state shifts to state 4-5.

In state 4-5, SU- is on and S +,
S-, SU +, SL +, and SL- are off. Transformer 1
The polarity of the secondary side voltage Vtr is inverted by the back electromotive force because S- is cut off, and becomes positive. On the primary side of the high-frequency transformer 4,
A current flows through a path of the DC power supply 2, DS +, the high-frequency transformer 4, and the DC power supply 2. On the secondary side of the high-frequency transformer 4, a current flows through the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SU-, DSU-, and the high-frequency transformer 4, and the cycloconverter output voltage Vc has a positive polarity. By turning on the S + switch from this state, the state shifts to state 4-6.

In state 4-6, S + and SU- are on,
S-, SU +, SL +, and SL- are off. On the primary side of the high-frequency transformer 4, a current flows through a path of the DC power supply 2, DS +, the high-frequency transformer 4, and the DC power supply 2.
The secondary voltage Vtr has a positive polarity. On the secondary side of the high-frequency transformer 4, a current flows through the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SU−, DSU− and the high-frequency transformer 4. The cycloconverter output voltage Vc has a positive polarity. By turning on SL- when the PWM signal rises from this state, the state shifts to state 4-7.

In state 4-7, S +, SU-, and SL- are on, and S-, SU +, and SL + are off. On the primary side of the high-frequency transformer 4, the current flowing through the path of the DC power supply 2, DS +, the high-frequency transformer 4, and the DC power supply 2 decreases, the current flowing to DS + becomes 0, and the current flowing direction is reversed. , DC power supply 2, high-frequency transformer 4, S +,
A current flows through a path of the DC power supply 2. The transformer primary side voltage Vtr has a positive polarity. On the secondary side of the high-frequency transformer 4, the current that has started flowing through the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SL−, DSL−, and the high-frequency transformer 4 increases, and the high-frequency transformer 4, the load 7,
The current flowing through the reactor of the output filter 6, SU-, DSU-, and the high-frequency transformer 4 decreases. The cycloconverter output voltage Vc is zero. From this state, on the secondary side of the high-frequency transformer 4, the current flowing through the path of the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SU-, DSU- and the high-frequency transformer 4 becomes zero, and Vc
The state shifts to the state 4-8 by becoming negative.

In state 4-8, S +, SU-, and SL- are on, and S-, SU +, and SL + are off. On the primary side of the high-frequency transformer 4, the DC power supply 2, the high-frequency transformer 4,
The current flows through the path of S +, DC power supply 2 and the transformer 1
The secondary voltage Vtr has a positive polarity. On the secondary side of the high-frequency transformer 4, a current flows through the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SL−, DSL−, and the high-frequency transformer 4. No current flows through the path of the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SU-, DSU-, and the high-frequency transformer 4. The cycloconverter output voltage Vc has a negative polarity. By turning off the SU- switch when the current is 0, switching is performed without generating a switching surge, which is an excessive voltage generated at both ends of the switch due to the leakage inductance of the transformer.
By turning off the switch of SU- in this way, state 4
Move to -9.

In state 4-9, S + and SL- are on,
S-, SU +, SL +, and SU- are off. On the primary side of the high-frequency transformer 4, the DC power supply 2, the high-frequency transformer 4,
The current flows through the path of S +, DC power supply 2 and the transformer 1
The secondary voltage Vtr has a positive polarity. On the secondary side of the high-frequency transformer 4, a current flows through the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SL−, DSL−, and the high-frequency transformer 4. The cycloconverter output voltage Vc has a negative polarity. By turning off the switch of S + from this state, the state shifts to state 4-10.

In state 4-10, SL- is on and S +
, S-, SU +, SL +, and SU- are off. The polarity of the transformer primary side voltage Vtr is inverted by the back electromotive force because S + is cut off, and becomes negative. On the primary side of the high-frequency transformer 4, the DC power supply 2, DS-, the high-frequency transformer 4, the DC power supply 2
The current flows through the path. On the secondary side of the high-frequency transformer 4, a current flows through the high-frequency transformer 4, the load 7, the reactor of the output filter 6, SL−, DSL−, and the high-frequency transformer 4. The cycloconverter output voltage Vc has a positive polarity. When the switch S- is turned on from this state, the state shifts to state 4-1.

As described above, in the period 4, the states 4-1 to 4-10 are sequentially repeated. As described above, the control method of the cycloconverter type high frequency link inverter of the present invention uses zero current switching (ZCS) when the polarity of the input current IL of the output filter and the output current Vo of the inverter are the same. The power supply commutation method of the control method is used, and the input current IL of the output filter, the output current Io of the inverter and the output voltage Vo of the inverter are used.
Current switching (ZC
The natural commutation method of the control method using S) is used.

That is, the power supply commutation method corresponds to period 1 and period 3 in FIG. 3, and period 1 and period 3 perform circuit operations corresponding to period A and period B in the prior art, respectively. In period A, states A-1 to A-8 are sequentially repeated,
In the period B, the states B-1 to B-8 are sequentially repeated.

In the natural commutation method, circuit operations corresponding to period 2 and period 4 in FIG. 3 are performed. State 2 in period 2
-1 to 2-10 are repeated in order.
Steps 1 to 4-10 are repeated in order. In other words, when the polarity of the output voltage of the cycloconverter type high frequency link inverter and the input current of the output filter are different, the high frequency inverter power amplifies a pulse signal with a constant duty ratio and alternately outputs a voltage to the high frequency transformer with positive and negative polarities. When a voltage of a power supply is applied to the high-frequency transformer, an output current of the cyclo-converter-type high-frequency link inverter can flow, and a semiconductor switch of the cyclo-converter that can increase the output current is turned on. The polarity of the output voltage is inverted, and after a certain period, the semiconductor switch of the cycloconverter capable of flowing the output current of the cycloconverter type high frequency link inverter and increasing the output current is turned on. By out The current flows through the semiconductor switch, and the current flowing through the semiconductor switch, which was turned on before the output polarity of the high-frequency inverter is inverted, is zero.After the current becomes zero, before the polarity of the output voltage of the high-frequency inverter is inverted. Turn off the semiconductor switch.

[0057]

As described above, according to the present invention,
If the polarity of the output voltage and the input current of the output filter are different, the semiconductor switch of the cycloconverter can be driven by a signal based on the PWM signal.
The control method that can be used only when the phase of current and voltage is the same, such as a pure resistance load, is a cycloconverter method even if any load is connected, such as a load with different current and voltage phases that has an inductance component or a capacitance component. A sine wave can be output from the high frequency link inverter. Further, since each switch of the cycloconverter performs zero current switching, noise and loss can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a cycloconverter type high frequency link inverter according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between an output voltage of a cycloconverter type high frequency link inverter and an input current of an output filter when the load is a pure resistance load.

FIG. 3 is a characteristic diagram showing a relationship between an output voltage of a cycloconverter type high frequency link inverter and an input current of an output filter when the load is a delay load having an inductance component.

FIG. 4 is a state transition diagram in the front part of period 2 showing an embodiment of the present invention.

FIG. 5 is a state transition diagram at the rear of period 2 showing the embodiment of the present invention.

FIG. 6 is a timing chart showing waveforms of respective units and drive signals of the respective semiconductor switches during period 2 in the embodiment of the present invention.

FIG. 7 is a state transition diagram at the front of period 4 showing an embodiment of the present invention.

FIG. 8 is a state transition diagram at the end of period 4 showing an embodiment of the present invention.

FIG. 9 is a timing chart showing the waveform of each part and the drive signal of each semiconductor switch during period 4 in the embodiment of the present invention.

FIG. 10 is a state transition diagram in the front part of a period A showing an example of a conventional embodiment.

FIG. 11 is a state transition diagram at the end of a period A showing a conventional embodiment.

FIG. 12 is a timing chart showing waveforms of respective units and a drive signal of each semiconductor switch during a period A in the conventional embodiment.

FIG. 13 is a state transition diagram in a front part of a period B showing a conventional embodiment.

FIG. 14 is a state transition diagram at the end of a period B showing a conventional embodiment.

FIG. 15 is a timing chart showing a waveform of each part and a drive signal of each semiconductor switch in a period B in the conventional embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Cycloconverter system high frequency link inverter 2 DC power supply 3 High frequency inverter 4 High frequency transformer 5 Cycloconverter 6 Output filter 7 Load S +, S-, SU +, SL +, SU-, SL- Semiconductor switches DS +, DS-, DSU +, DSL +, DSU-, DSL- Diode Vtr Primary voltage of high-frequency transformer Vc Output voltage of cycloconverter Vo Output voltage of cycloconverter high-frequency link inverter Io Output current of cycloconverter high-frequency link inverter ISU Current flowing through upper arm of ISU cycloconverter ISL Current flowing through lower arm of cycloconverter IL Input current of output filter

Claims (3)

[Claims] 1. A control method for a cycloconverter type high frequency link inverter, wherein a power commutation method is used when the polarities of an output current and an output voltage are the same, and a natural commutation method is used when the polarities are different. 2. A high-frequency inverter connected to an output terminal of a DC power supply and alternately outputting positive and negative polarities, and connected to an output terminal of the high-frequency inverter via a high-frequency transformer to switch an output polarity of the high-frequency inverter.
A cycloconverter-type high-frequency link inverter in which a cycloconverter that converts an alternating current having a frequency lower than the output frequency of the high-frequency inverter and an output filter that reduces high-frequency ripples is connected to an output of the cycloconverter. When the polarity of the output voltage and the input current of the output filter are different, the high-frequency inverter power-amplifies the pulse signal having a constant duty ratio and outputs a voltage to the high-frequency transformer alternately with positive and negative polarities. A semiconductor switch of the cycloconverter capable of flowing the output current of the cycloconverter type high frequency link inverter when being applied to the transformer and increasing the output current, and turning on the high frequency inverter After a certain period of time when the polarity of the output voltage of the cycloconverter is inverted and the output current of the cycloconverter type high frequency link inverter can flow and the semiconductor switch of the cycloconverter capable of increasing the output current is turned on. By doing so, the output current flows through the semiconductor switch, the current flowing through the semiconductor switch that was turned on before the output polarity of the high-frequency inverter is inverted is set to zero, and after the current becomes zero, the polarity of the output voltage of the high-frequency inverter is reduced. A semiconductor switch is turned off before the inverter is inverted. 3. The control method for a high frequency link inverter according to claim 1 or 2, wherein the PWM (Pulse Width Modul) is controlled.
A control method of a cycloconverter type high frequency link inverter, wherein a switch of the cycloconverter is controlled by a signal.