GB2451910A - Bidirectional DC AC converter with multiple buck boost converters and magnetic energy storage device. - Google Patents
Bidirectional DC AC converter with multiple buck boost converters and magnetic energy storage device. Download PDFInfo
- Publication number
- GB2451910A GB2451910A GB0716231A GB0716231A GB2451910A GB 2451910 A GB2451910 A GB 2451910A GB 0716231 A GB0716231 A GB 0716231A GB 0716231 A GB0716231 A GB 0716231A GB 2451910 A GB2451910 A GB 2451910A
- Authority
- GB
- United Kingdom
- Prior art keywords
- converter
- buck
- bidirectional
- boost
- terminals
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/66—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal
- H02M7/68—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters
- H02M7/72—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/79—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/797—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/66—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal
- H02M7/68—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/66—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal
- H02M7/68—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters
- H02M7/72—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/79—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/66—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal
- H02M7/68—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters
- H02M7/72—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/79—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/81—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal arranged for operation in parallel
Abstract
A DC to AC converter comprises a plurality of back to back bidirectional buck - boost converters 3 and 5 supplying a single phase load 1. The input voltage E 2 is a DC supply (or a DC load when converting AC to DC) Buck boost converter 3 supplies a terminal 4 of the load 1. Buck boost converter 5 supplies a terminal 6 of the load 1. The modulation depth is defined as the ratio of on time to on time plus off time for the converters 3 and 5. Switching signals are used to control switching devices Energy storage inductors L 7 and 8 may be individual coils wound onto individual magnetic cores or may be wound on the same core with a centre tap arrangement. The embodiment of figure 7 may be converted into isolated and multi phase variants which are both isolated and non isolated. Multi or 3 phase variants are shown on figure 13.
Description
A universal bidirectional DC to AC converter
Background and prior art:
Bidirectional DC to AC conversion is a required function of many modem electrically powered systems.
Applications include energy storage systems, renewable generation, and energy recovery power supplies. This invention is a circuit that converts DC electrical power into AC electrical power, and vice-versa, using one power electronic circuit. The significant advantage of the invention is that, in embodiments of the circuit topology, low frequency electrical isolation is achieved using high-frequency magnetic transformers thereby reducing circuit volume, weight, internal losses, complexity, failure and cost.
Prior art in this field include basic buck, boost and buck/boost topologies. Non-isolated versions of buck-boost converters are illustrated in Figure 1. In unidirectional versions, each circuit includes a diode (A), transistor (or equivalent) switch (B), inductor (C), capacitor (D), load (L) and a DC supply voltage (E). The unidirectional buck-boost converter is capable of producing an output voltage that is a weighted product of the input voltage.
The weighting factor is controlled by the duty ratio (or equivalent mechanism of varying the on to off time of the transistor) and typically the weighting can be varied from 0 to infinity under ideal circumstances, The buck boost converter operates by storing energy in an inductor (C) during the on period of the switch. The stored energy is then transferred to the output capacitor (D) via the diode (A) when the transistor is turned off. Such a circuit provides a variable output voltage. However, the output is of opposite polarity to the input DC voltage.
Bidirectional variants are shown in Figure 2 and these circuits allow DC to DC conversion to take place between the input and the output terminals. In such circuits the bidirectional function is provided by the inclusion of an additional diode (F) and transistor (or equivalent) switch (0) pair. One transistor and diode pair (A,B) is used for power flow in one direction, with the complementary transistor and diode pair (F,G) providing control power flow in the opposite direction.
Figures 3 and 4 shows isolated versions of the non-isolated circuits shown in Figure 1 and 2 respectively. In the isolated versions, the load is isolated from the supply by close-coupled inductor coils (H) that are operated at high frequency. In these circuits energy is stored in the core of the "primary" inductor during the on period of the transistor. This energy is transferred to the "secondary" coil when the switch is commutated off. This transfer of energy is typically via a magnetic core that couples the two inductor coils.
Typically, the power levels associated with the circuits identified in Figure 1-4 are limited by the effects of transformer leakage inductance. Snubber energy recovery circuits, both passive and active, can be applied to trap and recover stored energy in leakage inductance components. Figure 5 is one embodiment of a passive method of trapping and recovering leakage inductance energy (S). Figure 6 is an embodiment of an active energy recovery circuit (1).
Disclosure of Invention:
A universal bidirectional DC to AC converter, comprising multiple bidirectional back-to-back buck-boost converters, where each buck-boost convener comprises two transistor switches (or equivalent) switched in a complementary fashion and two associated anti-parallel diodes, a magnetic energy storage device comprising a coil or set of coupled coils, and a capacitor and the output of each buck-boost converter is arranged to generate an output voltage at an output terminal associated with each individual buck-boost converter where the multiple back-to-back buck-boost converters are controlled using modulation depths generated by additional circuitry such that the output waveforms are the desired AC waveforms of desired magnitude, frequency and phase displacement, or of desired arbitrary waveform, which is controlled by the selection of appropriate modulation depths according to the transfer function of the DC to AC converter, or alternatively, to supply a load connected to the DC terminals from an AC source connected to the AC terminals of the converter with appropriate modulation depths controlling the bidirectional back-to-back buck-boost converters according to the inverse of the transfer function of the DC to AC converter.
Brief Description of Drawings:
In order that the invention be more fully understood reference will now be made to the accompanying drawings, in which Figures 1-6 illustrate circuit diagrams of prior art in buck-boost converters.
figure 7 is one possible embodiment of the invention.
Figure 8 shows the relationship between input and output voltage and the modulation depth applied to the switching elements of the circuit.
Figure 9 illustrates one possible embodiment of the invention that provides isolation between the AC terminals and the DC terminals.
Figure 10 illustrates one possible embodiment of the invention that provides common emitter connections for the transistor (Or equivalent) switches located on the DC side of the system..
Figure 11 illustrates one possible embodiment of the invention that provides common emitter connections for the transistor (or equivalent) switches located on the AC side of the system.
Figure 12 illustrates one possible embodiment of the invention that provides a set of three-phase isolated terminals utilising an individual magnetic core to couple energy from DC side to AC side and vice-versa.
Figure 13 illustrates one possible embodiment of the invention that provides a set of three-phase isolated terminals utilising one multi-limbed magnetic core to transfer energy from DC side to AC side and vice-versa.
Detailed Description of Invention:
Figure 7 illustrates one embodiment of the invention. This circuit comprises two back-to-back bidirectional buck-boost converters, (3) and (5), supplying a single-phase load (1). The input voltage, E,, (2) is a DC supply (or a DC load when converting AC to DC). Buck-boost converter (3) supplies a terminal (4) of the load (1).
Buck-boost converter (5) supplies a terminal (6) of the load (I). The modulation depth, 6, is defined as the ratio of on-lime to the on-time plus off-time for the buck boost converter (3), and 6, is associated with buck boost converter (5). Converters (3) and (5) are supplied with complementaiy switching signals to control their associated switching devices such that the 8, is equal to (1-6). The load voltage, appears across the load (1).
With such an arrangement shown and with the described modulation depths applied to buck-boost converter (3) and (5) the transfer function between input voltage, E,, and output voltage, V, is shown in Figure 8 and is a function of 8. This circuit is a non-isolated, bidirectional DC to DC converter. If 6 is varied appropriately and has an offset of V2 then the output voltage, V,, is sinusoidal. Conversely, if the load (1) is replaced by an AC supply and 5 varied appropriately a controllable DC output can be generated at the DC source (2). Switching waveforms to control 8 of each converter can be generated using prior art methods of 6 control including PWM, PPM, hysteresis etc. The energy storage inductors, L, and L, (7) and (8) respectively, can be individual coils wound on individual magnetic cores, or to reduce component count, can be wound on the same core with a centre tap arrangement.
A key technical advantage of this embodiment over other circuit topologies is that the circuit utilises single-ended power switching devices that are simple to apply at high voltage and power levels, unlike standard bridge leg circuits. In addition, the output voltage can be of either polarity.
The basic embodiment shown in Figure 7 can be converted into isolated versions and multi-phase variants which are both isolated and non-isolated. In addition, there are important modifications to the circuit topologies that provide important simplifications to the circuit, particularly energy recovery and common emitter configurations.
These will now be described.
Isolation of input and output In many applications isolation is necessary for safety and operational reasons. Isolation can be achieved in the invention by replacing the storage inductors (7) and (8) in each of the buck-boost converters with close coupled inductor coils where each close coupled coil has a primary and secondary winding that are electrically isolated from one another and are magnetically coupled via a magnetic core. Figure 9 illustrates an embodiment of the circuit where close coupled coils (11) and (12) replace the storage inductors (7) and (8). In such a Circuit, the AC output terminals (4) and (6) are now electrically isolated from the input supply (2). The magnetic core linking the close coupled inductors has a fundamental flux frequency that is equal to the switching frequency of the transistor switches of the associated buck boost converter. The technical advantage of such a system is that whilst the output frequency from the output terminals is low frequency, the core flux frequency is high (at the PWM frequency for example) therefore the core size is small and the overall volume of the power supply much reduced. Also, the use of close coupled coils provides a mechanism for control of the input-output transfer function using the turns ratio between the primary and secondary windings.
Common emitter topologies In each of the preceding circuits described, the emitter (or source) connection of each switching devices is at a potential that differs from its counterpart, or indeed any of the other switching devices in the circuit. Individual gate drive circuits are required for each switching device and in general, each gate drive must be isolated. Circuit topologies that have switching devices that share a common emitter (or source) are effective in reducing the number of isolation barriers associated with each gate drive. This reduces component count, cost, complexity and failure rate. Figure 10 is an embodiment of a common emitter configuration for the invention, where, in this case, the transistors on the primary side of the close-coupled inductors have a common emitter connection (16).
The transistors (17) arid (18) can then be driven from gate drives that share the same power source and associated isolation barriers. In addition, this embodiment of the invention has close-coupled coils (19) for each buck boost converter wound on the same magnetic core, thereby reducing component count and cost. However, such an embodiment of the invention does not necessarily require the use of a single magnetic core and can use individual cores as shown in previous examples.
Figure II is an embodiment of the invention showing how the secondary transistor switches can be rearranged from that shown in Figure 10 into a common emitter (or source) connection thereby eliminating an isolated gate drive. The transistors (20) and (21) share a common emitter (22). The circuit maintains the same operational features of the basic embodiment of the invention but now has isolation and common emitter connections for pairs of transistor switches Multiple phase outputs Embodiments of the invention have illustrated DC to single phase AC conversion, and vice-versa. The bidirectional buck boost, back to back topology can be extended to provide multiple phase outputs, for example, three-phase. Figure 12 illustrates one such embodiment of the invention. In this case three phase outputs arc generated at the output terminals (23-25) by three back to back bidirectional buck boost converters and can supply a three phase load (26-28) which in this case is shown as a delta connected set of resistor, though the load may take any active or passive form with two or more phases and can be star, delta or using other connections topologies, The circuit shown is an isolated topology where isolation is provided by three close-coupled coils (29-31) which can be wound on individual magnetic cores, or on a multi-limbed magnetic core (32) as illustrated in the embodiment shown in Figure 13.
Multiple phase outputs with common emitter connections Figure 13 is an embodiment of the invention that utilises one core for all three phases of the AC supply. It is possible to rearrange the connections and the location of switching devices in order to achieve common emitter configurations on both the primary (DC) side and the secondary (AC) side of the isolation barrier. In Figure 14, the common emitter point for the primary side transistors (33-35) is shown (36) and an arrangement with common emitter configurations on both sides of the isolation barrier. The secondary side transistors (37-39) share a common emitter (40). The load can be star or delta connected or use other connection topologies.
Circuits including passive and active energy recovery AD the embodiments described can be implemented with snubber circuits to reduce the impact of stored energy in leakage inductance. The snubber circuits can be either passive or active in nature, examples of which are shown in Figures 5 and 6.
Claims (6)
- Cla!mr: I. A universal bidirectional DC to AC converter, comprising multiple bi-directional back-to-back buck-boost converters, where each buck-boost converter comprises two transistor switches (or equivalent) switched in a complementary fashion and two associated anti-parallel diodes, a magnetic energy storage device comprising a coil or set of coupled coils, and a capacitor and the output of each buck- boost converter is arranged to generate an output voltage at an output terminal associated with each individual buck-boost converter where the multiple back-to-back buck-boost converters are controlled using modulation depths generated by additional circuitry such that the output waveforms are the desired AC waveforms of desired magnitude, frequency and phase displacement, or of desired arbitrary waveform, which is controlled by the selection of appropriate modulation depths according to the transfer function of the DC to AC converter, or alternatively, to supply a load connected to the DC terminals from an AC source connected to the AC terminals of the converter with appropriate modulation depths controlling the back-to-back buck-boost converters according to the inverse of the transfer function of the DC to AC converter.
- 2. A universal bidirectional DC to AC converter according to claim I where isolation is achieved between the DC terminals and some, or all, phases of the AC terminals by using close coupled coils where the coupling mechanism is one or more magnetic, or other material, solid or gas, core and where some or all of the close coupled coils share a coupling core.
- 3. A universal bidirectional DC to AC converter according to preceeding claims where the transistor switching elements have a common emitter connection on the DC side.
- 4. A universal bidirectional DC to AC converter according to claims I and 2 where the transistor switching elements have a common emitter connection on the AC side.
- 5. A universal bidirectional DC to AC converter according to preceeding claims where active or passive snubber circuits are implemented.
- 6. A pulse-width modulating circuit substantially as described herein with reference to Figures 7-14 of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0716231A GB2451910A (en) | 2007-08-17 | 2007-08-17 | Bidirectional DC AC converter with multiple buck boost converters and magnetic energy storage device. |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0716231A GB2451910A (en) | 2007-08-17 | 2007-08-17 | Bidirectional DC AC converter with multiple buck boost converters and magnetic energy storage device. |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB0716231D0 GB0716231D0 (en) | 2007-09-26 |
| GB2451910A true GB2451910A (en) | 2009-02-18 |
Family
ID=38566688
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0716231A Withdrawn GB2451910A (en) | 2007-08-17 | 2007-08-17 | Bidirectional DC AC converter with multiple buck boost converters and magnetic energy storage device. |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2451910A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103560667A (en) * | 2013-09-10 | 2014-02-05 | 北京工业大学 | Bidirectional power converter for vehicle hybrid energy storage system |
| WO2014184254A1 (en) * | 2013-05-14 | 2014-11-20 | Thomas Schweizer | Converter circuit |
| US20160118825A1 (en) * | 2014-10-28 | 2016-04-28 | Renesas Electronics America Inc. | High voltage generation method at battery system |
| CN105634321A (en) * | 2016-03-17 | 2016-06-01 | 福州大学 | High-reliability single-phase bidirectional DC-AC converter and control method thereof |
| CN105958829A (en) * | 2016-05-25 | 2016-09-21 | 重庆大学 | Isolation type bidirectional buck-boost converter and work method |
| CN106849731A (en) * | 2017-04-13 | 2017-06-13 | 盐城工学院 | A kind of control method of buck-boost grid-connected inverter |
| CN106877722A (en) * | 2017-04-13 | 2017-06-20 | 盐城工学院 | A kind of highly reliable buck-boost grid-connected inverter |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1266305A (en) * | 2000-03-23 | 2000-09-13 | 南京航空航天大学 | Electric capacity energy storage type bidirectional converter |
| US20050218876A1 (en) * | 2004-03-31 | 2005-10-06 | Denso Corporation | Reversible buck-boost chopper circuit, and inverter circuit with the same |
| EP1657807A2 (en) * | 2004-11-15 | 2006-05-17 | General Electric Company | Bidirectional buck-boost power converter |
-
2007
- 2007-08-17 GB GB0716231A patent/GB2451910A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1266305A (en) * | 2000-03-23 | 2000-09-13 | 南京航空航天大学 | Electric capacity energy storage type bidirectional converter |
| US20050218876A1 (en) * | 2004-03-31 | 2005-10-06 | Denso Corporation | Reversible buck-boost chopper circuit, and inverter circuit with the same |
| EP1657807A2 (en) * | 2004-11-15 | 2006-05-17 | General Electric Company | Bidirectional buck-boost power converter |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014184254A1 (en) * | 2013-05-14 | 2014-11-20 | Thomas Schweizer | Converter circuit |
| CN103560667A (en) * | 2013-09-10 | 2014-02-05 | 北京工业大学 | Bidirectional power converter for vehicle hybrid energy storage system |
| US20160118825A1 (en) * | 2014-10-28 | 2016-04-28 | Renesas Electronics America Inc. | High voltage generation method at battery system |
| US9711984B2 (en) * | 2014-10-28 | 2017-07-18 | Renesas Electronics America Inc. | High voltage generation method at battery system |
| CN105634321A (en) * | 2016-03-17 | 2016-06-01 | 福州大学 | High-reliability single-phase bidirectional DC-AC converter and control method thereof |
| CN105634321B (en) * | 2016-03-17 | 2018-04-13 | 福州大学 | The single phase bidirectional DC AC converters and its control method of high reliability |
| CN105958829A (en) * | 2016-05-25 | 2016-09-21 | 重庆大学 | Isolation type bidirectional buck-boost converter and work method |
| CN105958829B (en) * | 2016-05-25 | 2019-05-10 | 重庆大学 | Isolation type bidirectional buck-boost converter and working method |
| CN106849731A (en) * | 2017-04-13 | 2017-06-13 | 盐城工学院 | A kind of control method of buck-boost grid-connected inverter |
| CN106877722A (en) * | 2017-04-13 | 2017-06-20 | 盐城工学院 | A kind of highly reliable buck-boost grid-connected inverter |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0716231D0 (en) | 2007-09-26 |
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| Date | Code | Title | Description |
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| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |