Inverter with voltage slope filter and hybrid devices

Abstract

Various examples are provided related to operation of parallel semiconductors with different or same switching frequencies and voltage slope filters. In one example, a power switching circuit includes a hybrid switching leg comprising two hybrid switches connected in series and a voltage slope filter connected in parallel with the hybrid switching leg. Each of the hybrid switches includes a wide bandgap device and a silicon power device. The voltage slope filter includes two switches connected in series and an inductor coupled between the two switches and between the two hybrid switches of the hybrid switching leg. Additional hybrid switching legs and voltage slope filters can be included.

Description

Docket: 221407-2120 INVERTER WITH VOLTAGE SLOPE FILTER AND HYBRID DEVICES CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to, and the benefit of, U.S. provisional application entitled “Inverter with Voltage Slope Filter and Hybrid Devices” having serial no.63 / 692,580, filed September 9, 2024, which is hereby incorporated by reference in its entirety. BACKGROUND

[0002] Switching regulators and power converters such as inverters are much preferred because of the increased efficiency they can potentially provide by rapidly connecting and disconnecting the power input as needed to maintain the output voltage at a desired level. Thus, the period when a voltage drop occurs across the regulator or power converter will be limited to relatively short periods of time and overall efficiency can be improved. However, such switching is cyclic and some portions of the switching cycle may be less efficient than others due to the instantaneous conduction conditions in the regulator or power converter circuit. The amount of current passing through the regulator or power converter can vary widely over a single switching cycle and between switching cycles, depending on input voltage or output current. SUMMARY

[0003] Aspects of the present disclosure are related to operation of parallel semiconductors with different or same switching frequencies and voltage slope filters. In one aspect, among others, a power switching circuit comprises a hybrid switching leg comprising two hybrid switches connected in series, each of said hybrid switches comprising a wide bandgap device and a silicon power device; and a voltage slope filter connected in parallel with the hybrid switching leg, the voltage slope filter comprising two switches connected in series and an inductor coupled between the two switches and between the two hybrid switches of the hybrid switching leg. In one or more aspects, the voltage slope filter canDocket: 221407-2120 further comprise capacitors connected in parallel with the two switches. The inductor can be coupled between the two switches at a first end and between the capacitors connected in parallel with the two switches at a second end. Each switch of the voltage slope filter can comprise at least one capacitor connected in parallel with that switch. In various aspects, at least one switch of the voltage slope filter can be switched on between operation of the wide bandgap device and operation of the silicon power device. The at least one switch of the voltage slope filter can be switched on during a transition period. The silicon power device can be controlled at a first gate switching frequency and the wide bandgap device is controlled at a second gate switching frequency, the first gate switching frequency lower than the second gate switching frequency. The silicon power device and the wide bandgap device can be controlled at a common gate switching frequency. The hybrid switching leg can form a half-bridge circuit.

[0004] In various aspects, the power switching circuit can comprise a second hybrid switching leg comprising two hybrid switches connected in series, each of said hybrid switches comprising a wide bandgap device and a silicon power device; and a second voltage slope filter connected in parallel with the second hybrid switching leg, the voltage slope filter comprising two switches connected in series and a second inductor coupled between the two switches of the second voltage slope filter and between the two hybrid switches of the second hybrid switching leg. The second voltage slope filter can further comprise capacitors connected in parallel with the two switches. The second inductor can be coupled between the two switches at a first end and between the capacitors connected in parallel with the two switches at a second end. At least one switch of the second voltage slope filter can be switched on between operation of the wide bandgap device and operation of the silicon power device. The at least one switch of the second voltage slope filter can be switched on during a transition period. The hybrid switching legs can form a full-bridge circuit.

[0005] In one or more aspects, the power switching circuit can comprise a third hybrid switching leg comprising two hybrid switches connected in series, each of said hybridDocket: 221407-2120 switches comprising a wide bandgap device and a silicon power device; and a third voltage slope filter connected in parallel with the third hybrid switching leg, the voltage slope filter comprising two switches connected in series and a third inductor coupled between the two switches of the third voltage slope filter and between the two hybrid switches of the third hybrid switching leg. The third voltage slope filter can further comprise capacitors connected in parallel with the two switches. The third inductor can be coupled between the two switches at a first end and between the capacitors connected in parallel with the two switches at a second end. At least one switch of the third voltage slope filter can be switched on between operation of the wide bandgap device and operation of the silicon power device. The at least one switch of the third voltage slope filter can be switched on during a transition period. The hybrid switching legs can form a three-phase bridge circuit. The hybrid switching legs can form a portion of a multi-phase bridge circuit.

[0006] Other systems, methods, features, and advantages of the present disclosure will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present disclosure, and be protected by the accompanying claims. In addition, all optional and preferred features and modifications of the described embodiments are usable in all aspects of the disclosure taught herein. Furthermore, the individual features of the dependent claims, as well as all optional and preferred features and modifications of the described embodiments are combinable and interchangeable with one another. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.Docket: 221407-2120

[0008] FIGS.1A-1D illustrate examples of hybrid switches, in accordance with various embodiments of the present disclosure.

[0009] FIG.2A illustrates an example of an inverter circuit employing the hybrid switches of FIGS.1A-1D, in accordance with various embodiments of the present disclosure.

[0010] FIG.2B illustrates an example of an inverter circuit employing a voltage slope filter with hybrid switches of FIGS.1A-1D, in accordance with various embodiments of the present disclosure.

[0011] FIG.3 illustrates an example of switching of the voltage slope filter and hybrid switches, in accordance with various embodiments of the present disclosure.

[0012] FIGS.4 and 5 illustrate examples of full-bridge inverter and three-phase inverter circuits, in accordance with various embodiments of the present disclosure. DETAILED DESCRIPTION

[0013] Disclosed herein are various examples related to operation of parallel semiconductors with different or same switching frequencies and voltage slope filters. Reference will now be made in detail to the description of the embodiments as illustrated in the drawings, wherein like reference numbers indicate like parts throughout the several views.

[0014] At light loads where conduction losses are reduced, the amount of power consumed by the rapid switching, referred to as switching losses, becomes a significant fraction of the total power consumption of the regulator or power converter. Switching losses can be substantially reduced by so-called hard switching or eliminated by so-called soft switching using wide bandgap semiconductor. Conversely, at heavy loads where high current is drawn through the regulator or power converter, conduction losses in the switches, generally wide bandgap MOSFETs since they are well-suited to operation in a hard- switching or soft-switching mode, tend to predominate because the conduction path in MOSFETs is substantially resistive. Conduction losses theoretically could be mitigated by placing a large number of MOSFETs in parallel to reduce currents in individual MOSFETsDocket: 221407-2120 and thus reduce the voltage drop. However, such a parallel connection of many switches is not generally practical due to the cost of multiple switching devices. By operating a silicon power device connected in parallel with a wide bandgap device at a lower switching frequency than the wide bandgap device, the switching loss and conduction loss can be significantly reduced since the switching frequency of the silicon power device is effectively reduced.

[0015] Referring to FIGS.1A-1D, shown are schematic diagrams illustrating examples of hybrid switch arrangements in accordance with various embodiments of the present disclosure. The hybrid switch arrangements include a silicon power device S1 connected in parallel with a wide bandgap device M1. The silicon power device S1 can be, e.g., a silicon controlled rectifier (SCR) as shown in FIGS.1A and 1C or an insulated-gate bipolar transistor (IGBT) as shown in FIG.1B and 1D. The wide bandgap device M1 can be a metal oxide semiconductor field-effect transistor (MOSFET) device. For soft switching, the silicon power device S1 also has a diode D1 connected in parallel with the conduction terminals thereof as shown in FIGS.1A and 1B. The wide bandgap device M1 also includes a similarly connected diode referred to as a body diode. Each transistor is controlled by a corresponding gate control signal GS1 or GM1 with the silicon power device S1 operated at a lower switching frequency than the wide bandgap device M1.

[0016] The silicon power device S1 and the wide bandgap device M1 can operate with different or the same switching frequencies. For example, the silicon power device S1 can operate at a low switching frequency (for example, at an operational frequency of 60 Hz) and the wide bandgap device M1 can operate at a high switching frequency (for example, a frequency of 20 kHz). The silicon power device S1 is able to handle most currents at a low turn-on voltage with no severe switching losses. The wide bandgap device can operate at a high switching frequency (e.g., in a kilohertz frequency range) at low current with an inexpensive cost. By paralleling the semiconductors with different or same stitching frequencies, the overall conduction and switching losses can be reduced. At the same time,Docket: 221407-2120 the system cost is reduced. The following table summarizes the advantages and benefits of the proposed configuration. Cost Performance Proposed hybrid switches Very Low Very Goodeerrng now o . , s own s an exampe o an nverer crcu empoyng the hybrid switch FIGS.1A or 1B. It should be understood that examples of inverter circuits using the hybrid switches in other zero voltage switching inverters are considered to be within the scope of the present disclosure.

[0018] As illustrated in FIG.2A, the inverter circuit comprises two hybrid switches, which alternately connect the DC+ and DC− busses, which receive power from a power supply, battery or the like, generically illustrated as Vdcand Cdc, to a load. (The current return path from the load is not shown.) The upper hybrid switch comprises a wide bandgap device M1, a silicon power device S1, and optionally a diode D1 as described with respect to FIGS. 1A-1D. In a conventional hard-switching inverter, only IGBTs S1 and S2 and diodes D1 and D2 are used. IGBT S1 conducts the positive current, while diode D1 conducts the negative freewheeling current. Similarly, IGBT S2 conducts the negative current, while D2 conducts the positive freewheeling current. With added MOSFETs M1 and M2, the positive currents are shared between M1 and S1 and the negative currents are shared between M2 and S2 while the positive and negative freewheeling currents are shared between the diodes D1, D2 and the body diodes of the MOSFETs M1 and M2, respectively. Two gate signals control each hybrid switch: GS1 and GM1 for the upper switch and GS2 and GM2 for the lower switch.Docket: 221407-2120

[0019] The inverter circuit of FIG.2A is perhaps the simplest and most generalized inverter circuit possible and its operation can be readily understood by those skilled in the art. Similarly, from the above discussion in connection with FIGS.1A-1D, it can be understood that the reduction of voltage drop across the hybrid switches (compared with the conventional circuit in which only the IGBTs S1 and S2 are used) can significantly improve efficiency when any significant current is drawn by the load and particularly at light loads which will occur near the times when the on-state is reversed between switches.

[0020] Using wide bandgap semiconductors in inverters offers advantages over Silicon (Si) solutions.3 to 10 times lower switching losses in SiC or GaN compared to Si devices allow for a more compact and efficient design for many applications. However, it is important to note that SiC or GaN devices are 2-5X more expensive and generate 5-10X more dv / dt noise.

[0021] FIG.2B illustrates an example of the proposed innovative circuit configuration comprising a voltage slope filter (VSF) 203 with hybrid SiC / GaN-Si devices 206 for high- power inverter applications, including electric vehicle inverters, solar inverters, energy storge systems, and others. This technology is expected to achieve 99% or higher peak efficiency under wide range, 5-10X reduction of dv / dt noise, and 50% reduction of total semiconductor cost verse all-SiC or GaN solutions. By including the voltage slope filter 203, the technical risk of the dv / dt-induced spurious turn-on can be eliminated in the state-of -the art hybrid SiC-Si solution while maintaining the fast speed switching.

[0022] FIG.3 illustrates an example of the switching of the voltage slope filter (VSF) 203 and the hybrid SiC / GaN-Si devices 206. Because of the delay between the switching of the devices in the hybrid device (G12 / G11 and B21 / G22), dv / dt current spikes and harmonics can be generated resulting in spurious operation of the devices. The addition of the VSF 203 can mitigate this and reduce the losses in the currents. By switching on the auxiliary transistor G1x during the transition period, the resonant inductor current can mitigate the effects and provide for a smooth output current as shown in FIG.3.Docket: 221407-2120

[0023] The hybrid switch is usable in virtually any soft-switching or hard-switching inverter, regulator or power converter. For example, FIG.4 schematically shows a full-bridge resonant snubber inverter (RSI) circuit including hybrid switches in accordance with the disclosure. The full bridge operation is to have hybrid switches turning on and off simultaneously for the positive load current and hybrid switches turning on and off simultaneously for the negative load current. To achieve soft switching for hybrid switches, the resonant current relies on the turning on of auxiliary switch Sr1 which creates a positive current to discharge capacitors so that the hybrid switches can be turned on under zero voltage conditions. Similarly, for the negative current cycles, the negative resonant current relies on the turning on of auxiliary switch Sr2 to discharge capacitors to achieve soft switching for the hybrid switches. FIG.5 illustrates application of the hybrid switch in accordance with the disclosure in a three-phase inverter.

[0024] It is seen that the hybrid switch in accordance with the basic principles of the disclosure facilitates design and operation of soft switching or hard-switching power regulator and converters and power inverters while providing a significant improvement in light and / or heavy load efficiency in any such application. The hybrid switch can be embodied as discrete devices or a three (or four—for connecting an external delay or control) terminal switch package.

[0025] It should be emphasized that the above-described embodiments of the present disclosure are merely possible examples of implementations set forth for a clear understanding of the principles of the disclosure. Many variations and modifications may be made to the above-described embodiment(s) without departing substantially from the spirit and principles of the disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.

[0026] The term "substantially" is meant to permit deviations from the descriptive term that don't negatively impact the intended purpose. Descriptive terms are implicitly understood to be modified by the word substantially, even if the term is not explicitly modified by the word substantially.Docket: 221407-2120

[0027] It should be noted that ratios, concentrations, amounts, and other numerical data may be expressed herein in a range format. It is to be understood that such a range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. To illustrate, a concentration range of “about 0.1% to about 5%” should be interpreted to include not only the explicitly recited concentration of about 0.1 wt% to about 5 wt%, but also include individual concentrations (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.5%, 1.1%, 2.2%, 3.3%, and 4.4%) within the indicated range. The term “about” can include traditional rounding according to significant figures of numerical values. In addition, the phrase “about ‘x’ to ‘y’” includes “about ‘x’ to about ‘y’”.

Claims

Docket: 221407-2120 CLAIMS Therefore, at least the following is claimed:

1. A power switching circuit, comprising: a hybrid switching leg comprising two hybrid switches connected in series, each of said hybrid switches comprising a wide bandgap device and a silicon power device; and a voltage slope filter connected in parallel with the hybrid switching leg, the voltage slope filter comprising two switches connected in series and an inductor coupled between the two switches and between the two hybrid switches of the hybrid switching leg.

2. The power switching circuit of claim 1, wherein the voltage slope filter further comprises capacitors connected in parallel with the two switches.

3. The power switching circuit of claim 2, wherein the inductor is coupled between the two switches at a first end and between the capacitors connected in parallel with the two switches at a second end.

4. The power switching circuit of any one of claims 2 and 3, wherein each switch of the voltage slope filter comprises at least one capacitor connected in parallel with that switch.

5. The power switching circuit of claim 1, wherein at least one switch of the voltage slope filter is switched on between operation of the wide bandgap device and operation of the silicon power device.Docket: 221407-2120 6. The power switching circuit of claim 5, wherein the at least one switch of the voltage slope filter is switched on during a transition period.

7. The power switching circuit of claim 1, wherein the silicon power device is controlled at a first gate switching frequency and the wide bandgap device is controlled at a second gate switching frequency, the first gate switching frequency lower than the second gate switching frequency.

8. The power switching circuit of claim 1, wherein the silicon power device and the wide bandgap device are controlled at a common gate switching frequency.

9. The power switching circuit of claim 1, wherein the hybrid switching leg forms a half- bridge circuit.

10. The power switching circuit of claim 1, comprising: a second hybrid switching leg comprising two hybrid switches connected in series, each of said hybrid switches comprising a wide bandgap device and a silicon power device; and a second voltage slope filter connected in parallel with the second hybrid switching leg, the voltage slope filter comprising two switches connected in series and a second inductor coupled between the two switches of the second voltage slope filter and between the two hybrid switches of the second hybrid switching leg.

11. The power switching circuit of claim 10, wherein the second voltage slope filter further comprises capacitors connected in parallel with the two switches.Docket: 221407-2120 12. The power switching circuit of claim 11, wherein the second inductor is coupled between the two switches at a first end and between the capacitors connected in parallel with the two switches at a second end.

13. The power switching circuit of claim 10, wherein at least one switch of the second voltage slope filter is switched on between operation of the wide bandgap device and operation of the silicon power device.

14. The power switching circuit of claim 10, wherein the hybrid switching legs form a full- bridge circuit.

15. The power switching circuit of claim 10, comprising: a third hybrid switching leg comprising two hybrid switches connected in series, each of said hybrid switches comprising a wide bandgap device and a silicon power device; and a third voltage slope filter connected in parallel with the third hybrid switching leg, the voltage slope filter comprising two switches connected in series and a third inductor coupled between the two switches of the third voltage slope filter and between the two hybrid switches of the third hybrid switching leg.

16. The power switching circuit of claim 15, wherein the third voltage slope filter further comprises capacitors connected in parallel with the two switches.

17. The power switching circuit of claim 16, wherein the third inductor is coupled between the two switches at a first end and between the capacitors connected in parallel with the two switches at a second end.Docket: 221407-2120 18. The power switching circuit of claim 15, wherein at least one switch of the third voltage slope filter is switched on between operation of the wide bandgap device and operation of the silicon power device.

19. The power switching circuit of claim 15, wherein the hybrid switching legs form a three-phase bridge circuit.

20. The power switching circuit of claim 15, wherein the hybrid switching legs form a portion of a multi-phase bridge circuit.

Images