VOLTAGE CONVERTER SYSTEMS
A voltage converter system includes a first DC-AC voltage converter that converts a first DC voltage signal to a first AC voltage signal. A DC link converts the first AC voltage signal to a second DC voltage signal. A second DC-AC voltage converter converts the second DC voltage signal to a second AC voltage signal. In another configuration a DC-AC voltage converter converts a DC voltage signal to a first AC voltage signal. An AC-AC voltage converter converts the first AC voltage signal to a second, lower-frequency AC voltage signal. In yet another configuration a first voltage converter portion converts a DC voltage signal to pulses of DC voltage. A second voltage converter portion converts the pulses of DC voltage to a relatively low-frequency AC voltage signal. The voltage converter system is selectably configurable as a DC-AC voltage converter or an AC-DC voltage converter.
Latest VANNER, INC. Patents:
- Bi-directional isolated DC-DC converter for the electrification of transportation
- Method of forming a transformer winding
- Bi-directional isolated DC-DC converter for the electrification of transportation
- DC-AC conversion circuit having a first double ended DC pulse stage and a second AC stage
- Power management and environmental control system for vehicles
This application claims priority to U.S. provisional application No. 61/785,958, filed Mar. 14, 2013, the contents of which are hereby incorporated by reference.
FIELDThe present invention relates generally to voltage converter systems, in particular to systems adapted to convert direct-current (DC) voltages to alternating-current (AC) voltages and vice versa.
BACKGROUNDA DC-AC voltage converter is an electrical system that changes a DC voltage to an AC voltage. The converted AC voltage may have any desired voltage level, waveform and frequency with the use of appropriate transformers, switching, filtering and control circuits. DC-AC voltage converters are used in a wide range of applications, from small switching power supplies in electronic devices such as computers to large electric utility high-voltage direct current applications that transport bulk power. DC-AC voltage converters are also commonly used to supply AC power from DC sources such as solar panels or batteries.
Given the foregoing, it is desirable to perform voltage conversion with a relatively high-frequency transformer driven by suitable power switching semiconductors. In one embodiment the present invention is a DC-AC voltage converter capable of operating with a relatively low DC voltage source input, such as from a battery power supply.
In some embodiments of the present invention the DC-AC voltage converter may be bidirectional, thereby capable of receiving an AC voltage signal and generating an output DC voltage signal. This arrangement is useful, for example, for charging a battery from an AC grid.
Preferably, a transformer is utilized to provide electrical isolation for DC-AC and AC-DC conversion. For example, an isolation transformer may be used between a DC voltage input (e.g., a battery) and an AC voltage output. The voltage converters of the present invention may be generally divided into several types according to the type of transformer selected. For example, the isolation transformers may be relatively low-frequency, on the order of 50/60 Hertz (Hz). Preferably, the isolation transformers are relatively high-frequency, on the order of tens or more kilohertz (kHz).
An aspect of the present invention is a voltage converter system that includes a first, high-frequency, DC-AC voltage converter configured to receive a first DC voltage signal and generate a first AC voltage signal. A DC link is configured to receive the first AC voltage signal and convert the first AC voltage signal to a second DC voltage signal. A second DC-AC voltage converter is configured to receive the second DC voltage signal and generate a second AC voltage signal.
Another aspect of the present invention is a voltage converter system that includes a DC-AC voltage converter configured to receive a DC voltage signal and generate a first, relatively high-frequency, AC voltage signal. An AC-AC voltage converter is configured to receive the first AC voltage signal and generate a second AC voltage signal. The frequency of the second AC voltage signal is preferably lower than the frequency of the first AC voltage signal.
Yet another aspect of the present invention is a voltage converter system that includes a first voltage converter portion that is configured to receive a DC voltage signal and convert the DC voltage signal to pulses of DC voltage. A second voltage converter portion is configured to receive the pulses of DC voltage and convert the pulses of DC voltage to a relatively low-frequency AC voltage signal. The voltage converter system is selectably configurable as a DC-AC voltage converter or an AC-DC voltage converter. In some embodiments of the present invention the first voltage converter portion includes a Ćuk-type voltage converter and a single-ended primary inductor converter (SEPIC) voltage converter, the Ćuk-type voltage converter and the SEPIC voltage converter being electrically combined to operate cooperatively.
Further features of the inventive embodiments will become apparent to those skilled in the art to which the embodiments relate from reading the specification and claims with reference to the accompanying drawings, in which:
An optional electrical filter 114 provides filtering of AC output voltage signal 112 to remove high-frequency components and/or limit electromagnetic interference (EMI) caused by the AC output voltage signal, resulting in a filtered AC output voltage signal 116. For certain applications where power quality is not a significant issue (such as a motor drive, as one example) a filter 114 configured to remove high-frequency components may be omitted.
With reference to
The topology of voltage converter system 300 may be divided into two portions for the purpose of explanation. A first voltage converter portion, 400 shown in
With continued reference to
One important difference between the Ćuk-type voltage converter and the SEPIC-type voltage converter is that the Ćuk-type voltage converter reverses the polarity of the input voltage while the SEPIC-type voltage converter does not. With reference again to
With reference now to
Ćuk and SEPIC voltage converters have one common disadvantage in that neither provide forward power conversion. Rather, they use passive components such as capacitors and inductors for energy storage. Consequently, the efficiency of these voltage converters depends very much on the quality factor of the aforementioned passive components. The quality factor of capacitors are generally good, but the quality factor of inductors are often less than desirable and often tend to worsen under high-current and low-voltage operating conditions. To reduce losses and increase efficiency, system 800 may be modified, replacing inductor 804 with an inductor/transformer 904, as shown in the circuit 900 of
With reference again to
A voltage converter 1000 is shown in
Voltage converter 1000 includes a first inductor 1002 and a second inductor 1004 connected in series, the first and second inductors each having an input and an output. A first capacitor 1006 is electrically intermediate the first and second inductors 1002, 1004, a first terminal of the first capacitor being electrically connected to the output of the first inductor and a second terminal of the first capacitor being electrically connected to the input of the second inductor. A third inductor 1008 and a fourth inductor 1010 are connected in series, the third and fourth inductors each having an input and an output. A second capacitor 1012 is electrically intermediate the third and fourth inductors 1008, 1010, a first terminal of the second capacitor being electrically connected to the output of the third inductor and a second terminal of the second capacitor being electrically connected to the input of the fourth inductor. A first switch 1014 is coupled between the input of the first inductor 1002 and the output of the third inductor 1008. A second switch 1016 is coupled between the output of the first inductor 1002 and the input of the third inductor 1008. A rectifier 1018 is arranged such that an anode of the rectifier is electrically connected to the second terminal of the first capacitor 1006, a cathode of the rectifier being electrically coupled to the second terminal of the second capacitor 1012. A third switch 1020 is electrically connected in parallel with the rectifier 1018. Voltage converter 1000 is configured to receive a DC voltage signal at the inputs of the first and third inductors 1002, 1008 and to generate an AC voltage signal at the outputs of the second and fourth inductors 1004, 1010.
Voltage converter system 1000 may further include third capacitor 1022, the third capacitor being electrically intermediate the second and fourth inductors 1004, 1010. A first terminal of third capacitor 1022 is electrically connected to the output of the second inductor 1004 and a second terminal of the third capacitor is electrically connected to the output of the fourth inductor 1010.
The foregoing configuration of voltage converter system 1000 has the advantage of relatively low inductor current and a low switch current, similar to the embodiment of
Inductors 1002, 1008 of voltage converter system 1000 may optionally be coupled magnetically to allow current balancing to occur. The current in inductor 1008 and switch 1014, and in inductor 1002 and switch 1016, may not necessarily ramp up identically as these inductor-switch pairs are independent of one another. However, when switches 1014, 1016 are opened the current flows in a complete circuit through the output (i.e., “a” and “b” of
In some embodiments of the present invention certain inductors of voltage converter system 1000 may be wound upon a common core. For example, inductors 1002, 1008 may be wound upon a common core. Similarly, inductors 1004, 1010 may be wound upon a common core. Winding the inductors upon a common core may provide certain advantages, such as a reduction in the overall size of the inductors.
One skilled in the art will appreciate that any suitable electronic components may be utilized for the circuits shown in the accompanying figures and described herein. For example, the switches may be any suitable types of power switching components including, without limitation, semiconductors such as bipolar junction transistors, field effect transistors and thyristors. Likewise, the diodes, capacitors, inductors and transformers shown in the accompanying figures may be any suitable types and values for a particular realization of the circuitry.
In addition, the circuits shown in the accompanying figures are simplified for purposes of explanation and are not intended to be limiting in any way. Accordingly, the circuits may include any suitable number and type of ancillary components including, without limitation, biasing, feedback and filtering components and circuitry as well as analog and/or digital monitoring, feedback and control circuitry.
While this invention has been shown and described with respect to a detailed embodiment thereof, it will be understood by those skilled in the art that changes in form and detail thereof may be made without departing from the scope of the claims of the invention.
Claims
1. A voltage converter system, comprising:
- a first, high-frequency, DC-AC voltage converter configured to receive a first DC voltage signal and generate a first AC voltage signal;
- a DC link configured to receive the first AC voltage signal and convert the first AC voltage signal to a second DC voltage signal; and
- a second DC-AC voltage converter configured to receive the second DC voltage signal and generate a second AC voltage signal.
2. The voltage converter system of claim 1, further including an electrical filter configured to limit electromagnetic interference generated by the second AC voltage signal.
3. A voltage converter system, comprising:
- a DC-AC voltage converter configured to receive a DC voltage signal and generate a first, relatively high-frequency, AC voltage signal; and
- an AC-AC voltage converter configured to receive the first AC voltage signal and generate a second AC voltage signal, a frequency of the second AC voltage signal being lower than the frequency of the first AC voltage signal.
4. The voltage converter system of claim 3, further including an electrical filter configured to limit electromagnetic interference generated by the second AC voltage signal.
5. The voltage converter system of claim 3 wherein the DC-AC voltage converter includes a transformer having a relatively high turns ratio, the transformer further operating under regulation.
6. A voltage converter system, comprising:
- a first voltage converter portion, configured to receive a DC voltage signal and convert the DC voltage signal to pulses of DC voltage; and
- a second voltage converter portion, configured to receive the pulses of DC voltage and convert the pulses of DC voltage to an AC voltage signal.
7. The voltage converter system of claim 6 wherein the pulses of DC voltage are half-sinusoidal pulses.
8. The voltage converter system of claim 6 wherein the first voltage converter portion includes:
- a Ćuk-type voltage converter; and
- a single-ended primary inductor converter (SEPIC) voltage converter,
- the Ćuk-type voltage converter and the SEPIC voltage converter being electrically combined to operate cooperatively.
9. The voltage converter system of claim 8 wherein the pulses of DC voltage produced by the electrically combined Ćuk-type voltage converter and SEPIC voltage converter have an output voltage about twice the voltage available from each converter individually, each voltage converter providing about half of output power delivered by the voltage converter system.
10. The voltage converter system of claim 8 wherein a switch and an inductor are common to both the Ćuk-type voltage converter and the SEPIC voltage converter.
11. The voltage converter system of claim 8 wherein the first voltage converter portion includes an inductor/transformer.
12. The voltage converter system of claim 6 wherein the first voltage converter portion includes:
- a first and a second inductor connected in series, the first and second inductors each having an input and an output;
- a first capacitor electrically intermediate the first and second inductors, a first terminal of the first capacitor being electrically connected to the output of the first inductor and a second terminal of the first capacitor being electrically connected to the input of the second inductor;
- a third and a fourth inductor connected in series, the third and fourth inductors each having an input and an output;
- a second capacitor electrically intermediate the third and fourth inductors, a first terminal of the second capacitor being electrically connected to the output of the third inductor and a second terminal of the second capacitor being electrically connected to the input of the fourth inductor;
- a first switch coupled between the input of the first inductor and the output of the third inductor;
- a second switch coupled between the output of the first inductor and the input of the third inductor;
- a rectifier having an anode and a cathode, the anode of the rectifier being electrically connected to the second terminal of the first capacitor and the cathode of the rectifier being electrically coupled to the second terminal of the second capacitor; and
- a third switch electrically connected in parallel with the rectifier,
- the voltage converter system being configured to receive a DC voltage signal at the inputs of the first and third inductors and to generate an AC voltage signal at the outputs of the second and fourth inductors.
13. The voltage converter system of claim 12, further including a third capacitor, the third capacitor being electrically intermediate the second and fourth inductors, a first terminal of the third capacitor being electrically connected to the output of the second inductor and a second terminal of the third capacitor being electrically connected to the output of the fourth inductor.
14. The voltage converter system of claim 12 wherein the switches switch synchronously.
15. The voltage converter system of claim 14 wherein the switches are semiconductors.
16. The voltage converter system of claim 12 wherein at least two inductors are magnetically coupled.
17. The voltage converter system of claim 6 wherein the voltage converter system is selectably configurable as a DC-AC voltage converter and an AC-DC voltage converter.
18. The voltage converter system of claim 6 wherein the second voltage converter portion further provides electrical isolation.
19. The voltage converter system of claim 6 wherein the AC voltage signal has a relatively low frequency.
20. The voltage converter system of claim 19 wherein the AC voltage signal has a voltage of about 120 VAC and a frequency of about 60 Hz.
Type: Application
Filed: Mar 13, 2014
Publication Date: Sep 18, 2014
Applicant: VANNER, INC. (HILLIARD, OH)
Inventors: ALEXANDER ISURIN (DUBLIN, OH), ALEXANDER COOK (DUBLIN, OH)
Application Number: 14/209,282
International Classification: H02M 7/537 (20060101); H02M 7/515 (20060101); H02M 7/06 (20060101);