Soft-switching auxiliary circuit for half bridge switching resonant inverter

Abstract

The invention relates to a soft switching auxiliary circuit for a half bridge switching resonant inverter comprising a DC phase inlet (8) connected via a circuit path (6) and a resonant inverter (10) connected to the DC phase input (8); a soft-switched auxiliary circuit (12) comprising one or more from a capacitor (20, 22) operating above or below the resonant frequency on the resonant inverter (10) an inductor (28), a diode (30, 32) and an isolated gate bipolar transistor (40, 42); a half-bridge switching circuit (16) converting the phase (9) from a direct current input into an alternating current phase output (50) connected half-bridging to the soft-switched auxiliary circuit (12). The soft-switched auxiliary circuit (12) is set to pass zero voltage in the capacitive region and zero current pass in the inductive region.

Description

[0001] SOFT-SWITCHING AUXILIARY CIRCUIT FOR HALF BRIDGE SWITCHING RESONANT

[0002] INVERTER

[0003] TECHNICAL FIELD

[0004] The invention relates to a soft switching auxiliary circuit for a half bridge switching resonant inverter which can enable zero voltage transition in the capacitive zone and zero current transition in the inductive zone and which can function within a wide load range.

[0005] PRIOR ART

[0006] An inverter is an electrical converter which converts direct current (DC) to alternative current (AC). The AC power generated at the outlet of the inverter can be at any voltage and frequency depending on the transformers, switching and control circuits used.

[0007] In the literature, the inverters made of semiconductors do not have movable parts. It has a wide usage area from low power switching power supplies used in computers to the high- power systems which supply power to electric distribution networks. They are generally used for converting DC power provided from the power sources such as solar panels, wind turbines and batteries to AC power in a controlled way. Briefly, inverters can convert DC power to AC power at the desired voltage, force and frequency by carrying out the reverse function of the AC-DC rectifiers.

[0008] Upon the increase of the need and interest in the renewable energy sources in the literature, the usage areas thereof increase rapidly in order to render the energy from these sources suitable for usage and to present it to the consumers.

[0009] EP3111722 discloses an improved induction cooker with a half-bridge resonant inverter having an adapter coil for heating ferromagnetic as well as non-ferromagnetic cookware. The subject matter invention proposes an induction heating cooker heating a ferromagnetic as well as non-ferromagnetic pan, having a half-bridge resonant inverter for converting DC voltage into high-frequency current. The inverter has a capacitive element, an induction heating coil, and a switching circuit having two switching devices switched on and off with a duty cycle of 50%.

[0010] BRIEF DESCRIPTION OF THE INVENTION

[0011] The object of the invention is to provide a soft-switched auxiliary circuit for a half-bridge switched resonant inverter that can operate at a switching frequency value above or below the resonant frequency, providing zero voltage crossing in the capacitive region, zero current crossing in the inductive region, and providing power control over a wide range. In order achieve the above mentioned objects, the subject matter invention comprises a soft switching auxiliary circuit for a half bridge switching resonant inverter comprising a DC phase inlet connected via a circuit path and a resonant inverter connected to the DC phase input; a soft-switched auxiliary circuit comprising one or more from a capacitor operating above or below the resonant frequency on the resonant inverter an inductor, a diode and an isolated gate bipolar transistor; a half-bridge switching circuit converting the phase from a direct current input into an alternating current phase output connected half-bridging to the soft- switched auxiliary circuit. In the soft switching auxiliary circuit for a half bridge switching resonant inverter, the soft-switched auxiliary circuit is set to pass zero voltage in the capacitive region and zero current pass in the inductive region. Thus, a zero current transition or zero voltage transition in accordance with the incoming phase is provided with a resonant inverter. Efficiency of use can be achieved, especially in induction cookers, with a resonant inverter that can operate both with zero current passing and zero voltage transition.

[0012] In a preferred embodiment of the invention, the soft switching auxiliary circuit comprises a parallel resonant auxiliary switch. Therefore, a soft switching formation is provided by the resonance connection of at least two switches from an auxiliary switch formed with the parallel resonance of an isolated-gate bipolar transistor and a diode in a resonant inverter. Moreover, capacitive and inductive circuit elements are connected to the auxiliary circuit over a circuit path in order to provide soft switching.

[0013] In a preferred embodiment of the invention, the half bridge switching circuit comprises one or more main switches with parallel resonance. Therefore, a half bridge switching formation is provided by the resonance connection of at least two switches from a main switch formed with the parallel resonance of an isolated-gate bipolar transistor, a diode and a capacitor in a resonant inverter. Moreover, it is connected to the auxiliary circuit over the circuit path in a half bridging way in order to provide half bridge switching.

[0014] In a preferred embodiment of the invention, the soft switching auxiliary circuit is connected to the resonant inverter over a circuit path providing power control in the range of 100W to 10kW. Thus, a wide range of power control in the resonant inverter can be achieved by the soft switching auxiliary circuit.

[0015] In a preferred embodiment of the invention, an auxiliary switch comprises a diode and an isolated-gate bipolar transistor. Thus, by providing an auxiliary switching circuit. In a preferred embodiment of the invention, the main switch comprises a capacitor, a diode and an isolated-gate bipolar transistor. Thus, by providing an main switching circuit.

[0016] BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Fig. 1 is the general view of the circuit diagram of the soft switching auxiliary circuit for a half bridge switching resonant inverter of the present invention.

[0018] DETAILED DESCRIPTION OF THE INVENTION

[0019] In this detailed description, the embodiment of the subject matter is described in a non limiting manner and with reference to the examples for clarification.

[0020] Fig. 1 shows the circuit diagram in general of the soft switching auxiliary circuit for a half bridge switching resonant inverter of the present invention. The soft switching auxiliary circuit for a half bridge switching resonant inverter consists of a resonant inverter (10) circuit structure which for example can be used in an induction heating cooker and serve as an auxiliary circuit (12) for resonant inverters (10), convert the phase (9) from the direct current inlet to the alternative current phase outlet (50) and which is connected to the direct current phase inlet (8) over a circuit path (6). In the present invention, the resonant inverter (10) consists of a soft switching auxiliary circuit (12) and a half bridge switching circuit (16) which converts the phase (9) from the direct current inlet to the alternative current phase outlet (50) and which is connected to the soft switching auxiliary circuit (12) in a half bridging way. Also, all transistors used in the present invention serve as an isolated-gate bipolar transistor (40, 42, 44, 46). The soft switching auxiliary circuit (12) in the resonant inverter (10) has zero voltage transition in the capacitive zone and zero current transition in the inductive zone. The soft switching auxiliary circuit (12) is formed by the connection of an auxiliary switch (13), an inductor (28), an auxiliary circuit upper capacitor (20) and an auxiliary circuit lower capacitor (22) in the circuit path (6) so as to function above or below the resonance frequency on the resonant inverter (10). The auxiliary switch (13) consists of an auxiliary switching transistor (40) having a parallel resonance connection and an auxiliary switching diode (30) having a parallel resonance connection to the auxiliary switch (13) such that the electricity transmission direction will be from anode to cathode. The auxiliary switch (13) is connected over the circuit path (6) at the node point where the capacitors (20, 22) are connected to each other for providing an electric flux transmission therebetween. At the outlet of the auxiliary switch (13), the negative end of the inductor (28) is connected in an electric flux providing way over the circuit path (6). At the positive end of the inductor (28), the half bridge switching circuit (16) is connected over the circuit path in a half bridging way. The half bridge switching circuit (16) is formed by the connection of an upper main switch (17) and a lower main switch (18) in the circuit path (6). The upper main switch (17) consists of an upper main switching transistor (44), an upper main switching diode (36) and an upper main switching capacitor (26) which are all in a parallel resonance connection. The circuit is completed by the connection over the circuit path of positive end of the inductor (28) at the node point where the switches (17, 18) are connected to each other for providing an electric flux therebetween.

[0021] In addition, the present invention provides the following advantages:

[0022] There is a snubber cell design in domestic type induction cookers which can work with the soft switch (12) in all kinds of working regions (below and above the resonance frequency) for half bridge series-resonant inverter (10) which is one of the preferred inverters (10) working at medium powers.

[0023] As the new resonant inverter (10) can provide a wide power control range, it will cause the input voltage (8) range to increase.

[0024] Selecting the resonance frequency at higher values causes the circuit elements (20, 22, 28) to decrease in volume.

[0025] In terms of voltage stresses, auxiliary switches (13) are exposed to lower voltage stress in this study.

[0026] In this resonant inverter (10), the soft switching cell can also be used with an AC-AC series- resonant half bridge inverter (10).

[0027] Herewith, it is also possible to reduce the power losses operating in both the inductive region and the capacitive region with the soft-switched auxiliary circuit (12). The operating modes of the resonant inverter (10) according to the incoming phase (9) are given below;

[0028] • 1. Mode of operation: Only the sub-main switching diode (36) is output (50) in conduction.

[0029] • 2. Mode of operation: Phase (9) coming from the direct current input (8); Its output (50) is provided in conduction with the auxiliary circuit upper capacitor (20), the auxiliary circuit lower capacitor (22), the inductor (28), the first auxiliary switching transistor (40), the second auxiliary switching diode (32). Here, the auxiliary switch (12) conducts in a way that provides zero current switching and the inductor (28) tries to take the load current from the diode (32) by entering into resonance with the auxiliary circuit upper capacitor (20) and the auxiliary circuit lower capacitor (22). • 3. Mode of operation: Phase (9) coming from the direct current input (8); auxiliary circuit upper capacitor (20), auxiliary circuit lower capacitor (22), inductor (28), first auxiliary switching transistor (40), second auxiliary switching diode (32), upper main switching capacitor (24) and lower main switching capacitor (26) and its output (50) is provided in transmission. Here, after the inductor (28) receives all of the diode (32) current, the first auxiliary switching transistor charges the parasitic capacitor (26) of the lower main switch (18) and the parasitic capacitor (26) of the upper main switch (17) with the remaining energy (with the help of its source) before the circuit starts to work it starts to discharge its capacitor (24).

[0030] • 4th and 5th mode of operation: Phase (9) coming from the direct current input (8); Output in conduction (50) with auxiliary circuit upper capacitor (20), auxiliary circuit lower capacitor (22), inductor (28), first auxiliary switching transistor (40), second auxiliary switching diode (32), upper main switching diode (34) are provided. In addition, the phase (9) coming from the direct current input (8); in conduction with auxiliary circuit upper capacitor (20), auxiliary circuit lower capacitor (22), inductor (28), first auxiliary switching transistor (40), second auxiliary switching diode (32) and upper main switching diode (34) The output (50) is provided in the cutoff with the transistor (44). In both of these modes of operation, this operation ends when the diode (34) of the upper switch turns on. Here, free circulation of energy is provided between the capacitors (20, 22) and the inductor (28). Also, in this mode of operation, the transmission signal of the upper switch (17) must be given. The upper switch (17) is turned on with the zero-voltage transition technique under these operating conditions.

[0031] • 6. Mode of operation: Phase (9) coming from the direct current input (8); Output in conduction (50) with auxiliary circuit upper capacitor (20), auxiliary circuit lower capacitor (22), inductor (28), first auxiliary switching transistor (40), second auxiliary switching diode (32) and upper main switching transistor (44) are provided. In this mode of operation, the upper switch assumes the load current over time. Here, the inductor (28) drives the capacitors (20, 22) by resonating the current of the inductor (28) to zero. This mode of operation ends when the inductor (28) current reaches zero.

[0032] • 7th and 8th mode of operation: Phase (9) coming from the direct current input (8); It works in a way that provides the output (50) in conduction with the upper main switching transistor (44) or conducts with the upper main switching diode (34) and upper main switching transistor (44) of the alternating current phase (50). This mode of operation is the normal operation of the resonant inverter (10) in the capacitive region. Here, the load current in it changes direction and turns the diode (34) of the upper switch on. In this mode of operation, the transmission signal of the lower switch (18) must be interrupted. • 9. Mode of operation: It is that the output phase (50) operates on the upper main switching diode (34) in a conductive manner.

[0033] • 10. Mode of operation: It operates from the output phase (50) with the upper main switching diode (34), second auxiliary switching transistor (42), first auxiliary switching diode (30), inductor (28) and capacitors (20, 22). This mode of operation begins when the second auxiliary switching transistor (42) turns on. Here, the auxiliary switch (42) turns on with zero current switching. The inductor (28) tries to take the load current from the diode (30) by resonating with the capacitors (20, 22).

[0034] • 11. Mode of operation: Output phase (50), lower main switching capacitor (26), upper main switching capacitor (24), second auxiliary switching transistor (42), first auxiliary switching diode (30), inductor (28) and capacitors (20, 22). Here, after the inductor (28) receives all of the diode (30) current, it starts to charge the parasitic capacitor (26) of the lower switch and discharge the parasitic capacitor (24) of the upper switch with the remaining energy (with the help of its source) before the circuit starts to operate.

[0035] • 12th and 13th mode of operation: This mode of operation consists of output phase (50), sub-main switching diode (36), second auxiliary switching transistor (42), first auxiliary switching diode (30), inductor (28) and capacitors (20, 22). In addition, the output phase (50), sub-main switching diode (36), sub-main switching transistor (46), second auxiliary switching transistor (42), first auxiliary switching diode (30), inductor (28) and capacitors (20, 22) is also available. Here, this mode of operation ends when the diode (34) of the upper switch turns on. In addition, the energy in the inductor (28) and the capacitors (20, 22) provides free circulation. In this mode of operation, the transmission signal of the subkey 46 has to be given. The upper switch (44) is turned on with the zero voltage transition technique under these operating conditions.

[0036] • 14. Mode of operation: This mode of operation is provided through the output phase (50), sub-main switching transistor (46), second auxiliary switching transistor (42), first auxiliary switching diode (30), inductor (28) and capacitors (20, 22). Here, the upper switch (44) assumes the load current over time. Inductor (28) and capacitors (20, 22) cause the current of the inductor (28) to zero by resonance. This mode of operation ends when the inductor 28 current reaches zero.

[0037] • 14th and 15th mode of operation: This mode of operation provides conduction from the output phase (50) to the sub-main switching transistor (46). It also provides conduction from the sub-main switching diode (36) to the output (50). This mode of operation is the normal operating range of the resonant inverter (10) in the capacitive region. In these operating modes, the load current changes direction and the diode (34) of the upper switch turns on. In addition, the transmission signal of the sub-switch (46) has to be interrupted. REFERENCE NUMBERS

[0038] 6 Circuit path 24 Upper main switching capacitor

[0039] 8 Direct current phase inlet 26 Lower main switching capacitor

[0040] 9 Phase from the direct current inlet 28 Inductor

[0041] 10 Resonant inverter 30 Auxiliary switching diode

[0042] 12 Soft switching auxiliary circuit 34 Upper main switching diode

[0043] 13 Auxiliary switch 36 Lower main switching diode

[0044] 16 Half bridge switching circuit 40 Auxiliary switching transistor

[0045] 17 Upper main switching 44 Upper main switching transistor

[0046] 18 Lower main switching 46 Lower main switching transistor

[0047] 20 Auxiliary circuit upper capacitor 50 Direct current phase outlet 22 Auxiliary circuit lower capacitor

Claims

CLAIMS1- A soft switching auxiliary circuit for a half bridge switching resonant inverter comprising a DC phase inlet (8) connected via a circuit path (6) and a resonant inverter (10) connected to the DC phase input (8); a soft-switched auxiliary circuit (12) comprising one or more from a capacitor (20, 22) operating above or below the resonant frequency on the resonant inverter (10) an inductor (28), a diode (30, 32) and an isolated gate bipolar transistor (40, 42); a half-bridge switching circuit (16) converting the phase (9) from a direct current input into an alternating current phase output (50) connected half-bridging to the soft-switched auxiliary circuit (12) characterized in that the soft-switched auxiliary circuit (12) is set to pass zero voltage in the capacitive region and zero current pass in the inductive region.2- The soft switching auxiliary circuit for a half bridge switching resonant inverter according to claim 1 , wherein the soft switching auxiliary circuit (12) comprises an auxiliary switch (13, 14) with parallel resonance.3- The soft switching auxiliary circuit for a half bridge switching resonant inverter according to claim 1 , wherein the half bridge switching circuit (16) comprises one or more main switches (17, 18) with parallel resonance.4- The soft switching auxiliary circuit for a half bridge switching resonant inverter according to claim 2, wherein the soft switching auxiliary circuit (12) is connected to the resonant inverter (10) over a circuit path (6) providing power control in the range of 100W to 10kW.5- The auxiliary circuit for a half bridge switching resonant inverter according to claim 2, wherein the auxiliary switch (13) comprises a diode (30) and an isolated-gate bipolar transistor (40).6- The auxiliary circuit for a half bridge switching resonant inverter according to claim 3, wherein a main switch (17, 18) comprises a capacitor (24, 26), a diode (34, 36) and an isolated-gate bipolar transistor (44, 46).

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