FI110897B - Voltage-breaking choppers - Google Patents

Description

110897 Voltage-breaking circuit breakers

Background of the Invention

The invention relates to a voltage-boosting circuit comprising a first inductance having a first terminal forming a positive 5-point breaker, a second inductance having a first terminal connected to a second terminal of a first inductance, a first diode having an anode connected to a second terminal of a second inductance. a second bypass diode connected in series such that the cathode of the first bypass diode is coupled to the anode of the second bypass diode while the cathode of the second bypass diode is further coupled to the cathode of the first diode; a collector coupled to the anode of the first bypass diode and emitted to form a negative entry point of the chopper, and an output terminal 15 having a second terminal connected to the first diode and one for the bypass diode cathodes and one for the semiconductor switch emitter when the output voltage of the breaker is formed between the terminals of the output capacitor.

As used herein, a diode is understood to mean any semiconductor component that conducts current in only one direction and prevents current from passing in the other direction. Similarly, the anode and * * * 'cathode names of the diode terminals used in the text refer to the corresponding terminals of any semiconductor component corresponding to the diode. In addition, in this text, the poles of a semiconductor switch, such as * · # • V transistor or FET, are exemplified as collector and emitted.

However, it is clear that depending on the type of semiconductor switch, its terminals are called: V: 25 under different names.

»· Voltage breaking circuit breakers are commonly used as a voltage source in various types of applications requiring reliable DC voltage. Tension; lifting choppers can be made up of very few components, however, the chopper losses and network properties are not the best * * '·; * '30 possible. The magnitude of the losses is significantly influenced by the magnitude of the back current peak of the main diode used in the chopper. The main diode is located in the lifting choppers: i in series with the main inductance, whereby all the load current passes through said .. 'diode. The diode's back-current peak, which occurs when the diode enters an inhibitory state, can thus pass through the semiconductor switch of the chopper as it enters the conductive state. Due to the larger back current peak, the magnitude of the switching losses becomes significant. In addition, the back current peak has a large amplitude of 110897 2 and a short duration, whereby the current peak causes problems in the form of electromagnetic interference. There is a solution to the problems caused by the back current peak using a passive damping circuit to which the back current peak flows when the diode is disconnected. Such a solution is disclosed in H. Levy et al. However, such a passive attenuation circuit increases the ripple in the input current of the chopper.

Another problem with voltage-increasing choppers is the switching frequency wave of the chopper input current. Due to the disturbances propagated by the ripple 10 into the feeder network, the chopper must have a current equalizing input filter. Traditionally, the filter is formed by a low-pass filter coupling of an inductive component and a capacitive component. However, such an LC filter increases the size and, consequently, the cost of the chopper. Further, if the ripple is strong, multiple filtration stages should be added to the inlet filter 15, which may cause difficulties in designing the chopper control arrangement. Adding a low-pass filter causes a phase delay, which results in adjustment, and consequently the behavior of the whole chopper in the change situations is impaired. The phase delay also reduces the power factor of the chopper. In addition, using a low-pass filter coupling, it is possible to achieve a perfectly uniform current waveform by 20 tons.

However, in connection with a conventional lifting chopper, there is proposed to be a • »· '·' / LC branch of the input current waveguide, in which the inductive and capacitive components are connected in series so that neither of the · · * components is present in the main circuit. Such a solution is disclosed in J. Wang et al. 'Modified boost converter with continuous input current mode and ripple free input current', PESC, 1996, p. 390.

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Brief Description of the Invention. . It is an object of the present invention to provide a voltage-boosting circuit breaker that avoids the above drawbacks and allows the voltage to be increased in a reliable and low-loss manner and with a smooth input current through simple switching. This object is achieved by: - ·· a voltage-boosting circuit breaker according to the invention, characterized in that the circuit breakers further comprise · a “filter capacitor and a filter inductance having a series switch”: 35 fields connected from the point between the first inductance and the second inductance to the emitter 110; 3, a third inductance coupled from a point between the first inductance and the second inductance to the collector of the semiconductor switch.

The invention is based on the idea of adding a waveguide-reducing coupling of an input current to a voltage-increasing interrupter having a circuit for reducing the losses caused by the back current peak of the 5 main diodes. With the known filtering circuit comprising only one inductance and a capacitor, only the current ripple caused by the main inductance of the chopper can be removed from the input current. Thus, an inductive component must be coupled to the circuit breaker in series with the switch component in order to filter out the ripple component of the circuit breaker input current caused by the back-peak reducing loss circuit.

The advantage of the voltage-increasing chopper according to the invention is the low losses and low interference levels both for the mains and radiated interference. The advantages are achieved by a simple and thus low-component solution.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be further described in connection with preferred embodiments, with reference to the accompanying drawings, in which:

Figure 1 shows the basic structure of a lifting chopper; and Figure 2 shows a lifting cutter according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The basic structure of a voltage-increasing chopper according to Fig. 1: consists of a first inductance L1 or main inductance, a first diode D1, a semiconductor switch S and an output capacitor Cd. The above-mentioned components can be used to form a working voltage-raising interruption as shown in Figure 1. Such a lifting chopper is commonly called a Boost-type chopper. The circuit input voltage Vs is connected, as shown in the figure, between the inductance L1 and the emitter of the switch S. The output voltage Vout consists of a voltage across the output capacitor.

\: 30 The output voltage is generated by alternating switch S to the conductive state and to the conductive state by appropriate switch control. The magnitude of the output voltage is determined by the pulse ratio of the switch control, i.e. how long from one. · During the switch cycle, the switch is kept in the conductive state.

Figure 2 shows a voltage-increasing breaker according to the invention.

According to the invention, the chopper comprises a first inductance L1, the first pole of which 110897 4 forms a positive entry point of the chopper. A second inductance L2 is connected in series with the first inductance. With the second inductance there is still the first diode D1 in the series. The first inductance and the first diode functionally correspond to corresponding components of the basic structure shown in Figure 1. Similarly, the output capacitor Cd coupled to the cathode of the first diode and the semiconductor switch S coupled to the second terminal of the first inductance via a series inductance L3 correspond to the components of the basic structure in functional terms.

The circuit according to the invention further comprises a series connection of the first and second bypass diode D2, D3. As shown in Figure 2, the bypass diodes are connected in series in parallel. The cathode of diode D3 is connected to the cathode of the first diode. The voltage-increasing chopper further comprises, according to the invention, a damping capacitor Cr connected between a point between the second inductance L2 and the first diode D1 to a point between the bypassing diodes D2, D3.

The coupling of the above bypass diodes D2, D3, the second inductance L2 and the attenuator capacitor Cr, when added to the basic circuit of Fig. 1, provides an attenuation circuit designed to reduce the peak current of the diode D1 ta-20 and thereby reduce switching losses. The back current peak is formed as the diode moves out of the conductive state, whereby a sharp current peak in the blocking direction flows through the diode. Since the turning off of the diode D1 and the switching of the controllable semiconductor switch S to a conductive state occur by · · 9: · · *, the diode's back current peak tends to pass through the semiconductor switch:, ·· 25. A significant part of the power losses of semiconductor switches is due to the losses during the switching. The magnitude of these power losses can be minimized by minimizing the current flowing through the switch at the moment of switching on and off. In this case, minimizing the back current peak of diode D1 will reduce the power losses to-. ·,: Bye.

The circuit breakers according to the invention further comprise a filtering circuit consisting of a filtering capacitor Cs and a filtering inductance Ls, which are connected as shown in Fig. 2 between the second terminal of the first inductance and the emitter of the semiconductor switch. The purpose of the filtering circuit is to eliminate: v, the switching frequency ripple of the input current. The circuit in question thus removes the waveguide input from the first inductance L1; stream. Since the inductance L2 of the damping circuit for reducing the effects of the rear current peak, which comprises the components L2, Cr, D2, D3, is in series with the first inductance, it is clear that the inductance L2 also causes a switching frequency component in the input current. This waveguide component cannot be removed by the filtering circuit Cs, Ls. However, the waveguide generated by inductance L2 ai-5 can be eliminated by connecting a third inductance L3 according to the invention to a collector of the semiconductor switch and at the anode of the first bypass diode D2 at a point between the first and second inductances L1, L2. The third inductance is preferably dimensioned to correspond to the inductance of the second inductance. With such a design, the input current ripple is minimized.

In accordance with a preferred embodiment of the invention, all inductive components of the breaker according to the invention are placed on the same core structure. With the same core structure, the inductive components have good mutual magnetic coupling. In addition, single-core coils integrated with 15 provide significant space savings. The magnitude of the magnetic coupling between the coils, i.e. the coupling coefficient, can be adjusted as desired by either the geometry of the coils or by additional inductive components. Such switching capacitors, which change the magnitude of the coupling coefficient, are placed in series on the cores of the core structure.

Further, the inductive components L1, L2 and L3 are preferably wound parallel to each other around the core, the component Ls having a winding direction different from the other components. Hereby, the polarities L1, L2 and L3 of the coils become the same and the polarity of the coil Ls · ·: is opposite to the polarities of the aforementioned windings as shown in Figure 2: 25.

It will be obvious to a person skilled in the art that as technology advances, the basic idea of the invention can be implemented in many different ways. The invention and its embodiments are thus not limited to the examples described above, but may alternate. within the scope of the claims.

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Claims (6)

A switch that raises the voltage comprising a first inductor (L1), whose first pole forms the positive input point of the switch, a second inductor (L2), whose first pole is connected to the second pole of the first inductor (L1), a first diode (D1), whose anode is connected to the second pole of the second inductor (L2), a first and a second access diode (D2, D3), which are connected in series so that the cathode of the first access diode (D2) is connected to the anode of the second pass diode (D3), the cathode of the second pass diode (D3) being coupled further to the cathode of the first diode (D1), an attenuation capacitor (Cr) coupled from a point between the second inductance and the first diode to a point between the series-connected access diodes, a semiconductor switch (S), whose collector is connected to the anode of the first access diode (D2) and whose emitter forms the negative input point of the switch, and an output capacitor (Cd), the second of which pole is connected to the device The cathode of the diode and the second pass diode and other poles to the emitter of the semiconductor, the output voltage of the switch forming an output capacitor between the poles, characterized in that the switch further comprises a filtering capacitor (Cs) and a filtering inductance (Cs). Ls), whose series circuit is coupled from the point between the first inductance (L1) and the second inductance (L2) to the emitter of the semiconductor switch, and a third inductance (L3) coupled from the point between it; the first inductance (L1) and the second inductance (L2) of the semiconductor switch collector. • '30 Switch according to claim 1, characterized in that the inductance values of the second (L2) and the inductance (L3) of the third inductor (L3) are equal. The circuit breaker of claim 1 or 2, wherein the inductances are: ·. windings wound around a core, characterized in that the winding "forming the first inductance (L1), the winding forming the second inductance (L2), the winding forming the third inductance (L3) and the winding forming the filtering inductance (Ls) arranged on the same core 4. A circuit breaker according to claim 3, characterized in that the coupling factors between the windings have been formed to the desired winding geometry. 5. A switch according to claim 3 or 4, characterized in that the coupling factors between the windings have been formed to the desired with separate inductive components which are connected in series with said windings. Switch according to claims 1-5, characterized in that the polarities of the winding forming the first inductance (L1), the winding forming the second inductance (L2) and the winding forming the third inductance (L3) are parallel, and the polarity of the winding forming the filtering inductance (Ls) is opposite in relation to these. »»