CN101834526B - Power conversion circuit and portable power supply device applicable to same - Google Patents

Abstract

The invention is a power switching circuit and applicable portable power supply unit, the power switching circuit receives a direct-current voltage, include at least: the flyback DC-DC converter is used for receiving DC voltage and converting the DC voltage into fixed high-voltage DC voltage; the capacitor is connected with the flyback DC-DC converter and is used for filtering the high-voltage DC voltage; and the direct current-alternating current converter is connected with the capacitor and used for converting the filtered high-voltage direct current voltage into alternating current voltage to be output. The invention can simplify the control mode of the internal circuit, and the transformer only needs to be provided with a single group of primary windings, thus reducing the manufacturing cost.

Description

Power conversion circuit and its applicable portable power supply device

technical field

The invention relates to a power conversion circuit, in particular to a power conversion circuit and a portable power supply device for it.

Background technique

Inverter (inverter) is a power converter that converts DC voltage into AC voltage output. It is suitable for places where DC power can be supplied to convert DC power into AC power. And it is used in automobiles or portable DC batteries, and its DC power is converted into AC power through an inverter to supply various portable electronic products, such as: notebook computers, mobile phones, MP3 players, cameras, lights or needs Emergency supply of AC power for life-saving purposes, etc., to solve the current dilemma that many portable electronic devices cannot be charged when users go out, resulting in equipment but no power available.

The known inverter uses a push-pull DC-DC converter (Push Pull DC-DC Converter) to boost the input DC voltage after receiving DC power, and then uses a full bridge DC-AC converter (Full Bridge DC-AC Converter) Convert high-voltage DC voltage into an analog AC voltage output to supply power to the connected load.

Although the known inverter uses a push-pull DC-DC converter (Push Pull DC-DC Converter) and a full-bridge DC-AC converter to convert the DC voltage into an analog AC voltage output to supply power to the load, but the known push-pull DC - The DC converter is to alternately switch between two switches and boost the voltage through the action of a transformer to generate a high-voltage DC voltage on the secondary side, and the secondary side needs to be rectified by a rectifier circuit composed of four diodes, It requires a large number of electronic components, including two main switching switches, two windings on the primary side of the transformer, and four rectifier diodes, resulting in complex circuits, bulky size, and high cost.

Furthermore, the relationship between the input DC voltage on the primary side of the push-pull DC-DC converter and the high-voltage DC voltage on the secondary side is the ratio of turns between the primary and secondary sides of the transformer, that is, the peak value of the output imitation AC voltage is equal to the input voltage A certain ratio. Therefore, the difference in the level of the input voltage will cause a large difference in the level of the output voltage, that is, the rate of change of the voltage is too large, which is easy to cause damage to the load.

In addition, the duty cycle of the push-pull DC-DC converter is fixed, which causes waste of input power at light load or no load, and cannot achieve the effect of energy saving.

And when using the known push-pull DC-DC converter to convert the voltage, the generated high-voltage DC voltage will change with the fluctuation of the input DC voltage, which will cause the high-voltage AC voltage converted and output by the full-bridge DC-AC converter to follow. fluctuation.

In order to solve the above-mentioned problems, a method has been developed to control the duty cycle of the push-pull DC-DC converter by using the detection output to imitate the AC voltage. This control method can only prevent the output voltage from being too high and damaging the load when the input voltage is at a high level. However, this control method is complex and has a slow response speed, and cannot provide good power quality.

In order to solve the above-mentioned problems of slow response speed and inability to provide good power quality, a new method has been developed to control the duty cycle of the full-bridge DC-AC converter by detecting the high-voltage DC level, so that the output imitation AC voltage value is a certain value. However, this kind of control method is complicated, and the response speed is slow, and it cannot provide good power quality.

Therefore, how to develop a power conversion circuit and a portable power supply device that can improve the above-mentioned defects of the known technology is an urgent problem to be solved at present.

Contents of the invention

The main purpose of the present invention is to provide a power conversion circuit and a portable power supply device for it, so as to solve the following defects of the push-pull DC-DC converter used in the traditional inverter: that is, the number of its constituent electronic components is large , and the push-pull DC-DC converter is matched with two switches, the internal transformer must be provided with two sets, and the secondary side needs four rectifier diodes, which makes the manufacturing cost higher and the feedback control method is also complicated, and The effect is not significant, and it is less power-saving at no-load and light-load conditions, and the high-voltage DC voltage generated by the push-pull DC-DC converter will change with the fluctuation of the input DC voltage, resulting in The simulated AC voltage output by conversion will fluctuate accordingly, which will cause faults such as load malfunction or burnout.

To achieve the above purpose, a broad implementation of the present invention is to provide a power conversion circuit that receives a DC voltage, at least including: a flyback DC-DC Converter (Flyback DC-DC Converter) for receiving a DC voltage, and converting the DC voltage into a fixed high-voltage DC voltage, and including a first-stage power supply circuit and a first control circuit; a capacitor connected to a flyback DC-DC converter for filtering the high-voltage DC voltage; and A DC-AC converter, connected to a capacitor, is used to convert the filtered high-voltage DC voltage into an AC voltage output; wherein the output waveform of the AC voltage is an AC voltage signal imitating a sine wave; wherein the AC voltage is a zero-voltage voltage Normally, the first control circuit controls a first switching element of the first stage power supply circuit to stop operating.

To achieve the above purpose, the present invention further provides a portable power supply device, which at least includes: an energy storage element for providing a DC voltage; a power conversion circuit, which is connected to the energy storage element and receives a DC voltage, and at least includes: a flyback type The DC-DC converter is used to receive the DC voltage and convert the DC voltage into a fixed high-voltage DC voltage, and includes a first-stage power supply circuit and a first control circuit; a capacitor, and a flyback DC-DC converter connected to filter the high-voltage DC voltage; and a DC-AC converter connected to the capacitor to convert the filtered high-voltage DC voltage into an AC voltage output; wherein the output waveform of the AC voltage is a sine-like AC A voltage signal; wherein when the AC voltage is at zero voltage level, the first control circuit controls a first switch element of the first stage power supply circuit to stop operating.

The power conversion circuit and the flyback DC-DC converter of the portable power supply device of the present invention output a fixed high-voltage DC voltage, which can make the DC-AC converter convert and output a stable high-voltage AC voltage with high transient response, and Flyback DC-DC converters have a small number of internal electronic components, and there are no multiple switches to switch alternately, which can simplify the internal circuit control method, and the transformer only needs to be equipped with a single set of primary windings, which can reduce manufacturing costs. When the voltage is at zero voltage level, controlling the first switching element to stop the switching action can achieve the effect of reducing energy loss.

Description of drawings

FIG. 1 is a circuit block diagram of a power conversion circuit according to a first preferred embodiment of the present invention.

Figure 2: It is a structural diagram of the internal components in Figure 1.

Fig. 3: It is an operation waveform diagram of the power conversion circuit shown in Fig. 2 .

FIG. 4 : It is a schematic diagram of the circuit block structure of the second preferred embodiment of the present invention.

The reference numerals in the above-mentioned accompanying drawings are explained as follows:

Detailed ways

Some typical embodiments embodying the features and advantages of the present invention will be described in detail in the description in the following paragraphs. It should be understood that the present invention can be changed in various ways without departing from the scope of the present invention, and that the description and illustrations therein are illustrative in nature rather than limiting the present invention.

Please refer to FIG. 1, which is a circuit block diagram of a power conversion circuit in the first preferred embodiment of the present invention. As shown in the figure, the power conversion circuit 1 of the present invention receives a DC voltage Vin, and at least includes a flyback DC-DC The converter 11, the capacitor 12 and the DC-AC converter 13 are used to boost the DC voltage Vin and convert it into an AC voltage Vo output to supply power to the connected load, wherein the flyback DC-DC converter 11 mainly receives DC voltage Vin, and convert the DC voltage Vin into a fixed high-voltage DC voltage V1, and the capacitor 12 is connected to the output terminal of the flyback DC-DC converter 11 and the input terminal of the DC-AC converter 13 to control the high-voltage DC voltage V1 is filtered, and finally the filtered high-voltage DC voltage V1 is converted into an AC voltage Vo by the DC-AC converter 13 connected to the capacitor 12 for output.

Please refer to FIG. 2, which is a structural diagram of the internal components of FIG. 1. As shown in the figure, in some embodiments, the flyback DC-DC converter 11 may include a first-stage power supply circuit 111, the first-stage The power supply circuit 111 may be composed of a transformer 112, a first switch element 113 and a rectifier circuit 114. The primary side Np of the transformer 112 is connected to the first switch element 113 and receives an input DC voltage Vin, which is based on the first switch element 113 The conduction or cut-off of the transformer 112 enables the energy storage, release and boosting of the transformer 112, and then rectifies and outputs the high-voltage DC voltage V1 through the rectification circuit 114, and the rectification circuit 114 can be but not limited to a diode element, which is connected to the transformer 112 The secondary side Ns is connected to mainly rectify the voltage induced by the secondary side Ns of the transformer 112 to output the high-voltage DC voltage V1. It can be seen from the above that the flyback DC-DC converter 11 of this embodiment has only Setting a single first switching element 113 and a single diode requires less electronic components, and does not require multiple switching switches to switch alternately. The control method of the entire internal circuit is relatively simple, and the transformer 112 only needs to be provided with a set of The primary winding can reduce the manufacturing cost, which improves the disadvantages of the known technology that there are many parts, the transformer is complicated to manufacture, and the manufacturing cost is high.

In some embodiments, the flyback DC-DC converter 11 may further include a feedback circuit 115 and a first control circuit 116, the first control circuit 116 may be but not limited to a pulse width modulation control circuit (PWM control circuit) or a pulse width modulation controller (PWMcontroller), and is connected with the feedback circuit 115 and the first switching element 113, mainly by outputting a control signal V2 to the first switching element 113 to control the first The switching element 113 operates.

As for, the feedback circuit 115 is connected with the rectification circuit 114 and the first control circuit 116, and is used to detect whether the high-voltage direct current voltage V1 outputted through the rectification circuit 114 is the same as a predetermined voltage value, for example: 110V, and the feedback circuit 115 will be based on the high-voltage direct current voltage V1. The voltage V1 corresponds to generate a feedback signal Vf to the first control circuit 116, so that the first control circuit 116 generates a control signal V2 according to the feedback signal Vf to control the switching frequency or duty cycle of the first switching element 113, due to the flyback The circuit characteristics of the DC-DC converter 11, by controlling the duty cycle of the switch on the primary side Np, the electric energy converted to the secondary side Ns can be rectified and filtered to obtain a fixed high-voltage DC voltage with high transient State response and high stability, so that the high-voltage DC voltage V1 output by the first-stage power supply circuit 111 conforms to the predetermined voltage value, and the secondary side output voltage of the push-pull DC-DC converter in the known technology will change with the input voltage. Shortcomings.

Please refer to FIG. 3, since the flyback DC-DC converter 11 used in the power conversion circuit 1 of the present invention can control the switching frequency or duty of the first switching element 113 through the feedback circuit 115 and the first control circuit 116 ratio, to adjust the voltage induced by the secondary side Ns of the transformer 112 and the high-voltage DC voltage V1 output by the first-stage power supply circuit 111. Therefore, when the input voltage value of the DC voltage Vin fluctuates, the flyback DC-DC converter 11 It will not be affected by fluctuations and will continue to output a fixed high-voltage DC voltage V1. This V1 has the characteristics of high stability and high transient response, which can solve the problem that the output AC voltage will fluctuate with the input DC voltage in the known technology. And cause load malfunction or burn out and other shortcomings.

Please refer to FIG. 2 again. In some embodiments, the DC-AC converter 13 may be, but not limited to, a full bridge DC-DC converter (Full Bridge DC-DC Converter), and may include a second-stage power supply circuit 131 and A second control circuit 132 , the second stage power supply circuit 131 is connected to the capacitor 12 and the second control circuit 132 . The second-stage power supply circuit 131 can be composed of multiple sets of second switching elements. In some embodiments, it can be composed of second switching elements Q1, Q2, Q3, and Q4. Please refer to FIG. 2 and FIG. 3, wherein Q1 and Q3 They act together, Q2 and Q4 act together, and are mainly turned on or off according to the control signal sent by the second control circuit 132. In each working cycle T, when Q1 and Q3 are turned on and Q2 and Q4 are turned off, the output The positive high-voltage DC voltage V1 (+V1), that is, the voltage output by the duty cycle (duty cycle) T1, on the contrary, when Q2 and Q4 are turned on and Q1 and Q3 are turned off, the negative polarity high-voltage DC voltage V1 ( -V1), that is, the output voltage of the duty cycle T2, and then convert the high-voltage DC voltage V1 into an AC voltage Vo for output.

Since the flyback DC-DC converter 11 can convert the received DC voltage Vin into a fixed high-voltage DC voltage V1 for output, it is only necessary to let the second control circuit 132 output a control signal with a fixed duty ratio, and then through the second The AC voltage Vo converted and output by the stage power supply circuit 131 can also be maintained at a fixed AC voltage, that is, the effective value of the AC voltage Vo is fixed, and will not fluctuate with the fluctuation of the voltage value of the DC voltage Vin, so that the power conversion circuit 1 can Provide a stable AC voltage Vo to the load terminal.

Please refer to FIG. 2 and FIG. 3 again. As shown in FIG. 3, the output waveform of the AC voltage Vo output by the DC-AC converter 13 of the present invention is a sine-like AC voltage signal (ModifySine Wave AC Output). In some embodiments, when the AC voltage Vo is at zero voltage level, that is, during the time period T3, the power conversion circuit 1 does not output power, and the high-voltage DC voltage V1 Instantaneous rise, the first control circuit 116 will control the first switching element 113 to stop running. Next, when the AC voltage Vo is at the -V1 voltage level, that is, the time period T2, the power conversion circuit 1 will restore the output power. In order to prevent the capacitor 12 from transmitting energy to the second-stage power supply circuit 13 and causing the high-voltage DC voltage V1 to drop instantaneously, The operation characteristic of the first control circuit 116 controlling the first switch element 113 to start running and stopping the first switch element 113 during the time period T3 is called SkipMode. Therefore, the high-voltage DC voltage V1 of the capacitor 12 will be maintained at a fixed and stable value, and will not vary with the input voltage Vin, and during the time period T3, the first-stage power supply circuit 111 will not operate, which can reduce loss and improve Known technology can't save the shortcoming of energy saving.

Please refer to FIG. 4, which is a schematic circuit block diagram of a portable power supply device according to a second preferred embodiment of the present invention. As shown in the figure, the portable power supply device 2 is mainly composed of an energy storage element 21 and a power conversion circuit 1, wherein the energy storage element 21 can be but not limited to a battery, mainly used to provide DC voltage Vin, and the internal circuit structure and operation principle of the power conversion circuit 1 have been described in the first preferred embodiment, so it will not be repeated.

Please refer to FIG. 3 again. Since the power conversion circuit 1 of the present invention controls the first switching element 113 to stop switching when the AC voltage Vo is at zero voltage level, that is, the time period T3, energy loss can be reduced. The power consumed by the energy storage element is very small, and the service time of the energy storage element can be extended.

To sum up, the power conversion circuit of the present invention and the flyback DC-DC converter of the portable power supply device to which it is applied output a fixed high-voltage DC voltage, which can make the conversion output of the DC-AC converter stable and high transient response High-voltage AC voltage, and the flyback DC-DC converter has a small number of internal electronic components, and there are no multiple switches to switch alternately, which can simplify the internal circuit control method, and the transformer only needs to be equipped with a single set of primary windings, which can reduce manufacturing costs. In addition, when the AC voltage is at the zero voltage level, controlling the first switching element to stop the switching action can achieve the effect of reducing energy loss.

Therefore, the power conversion circuit of the present invention and the portable power supply device to which it is applied are of great industrial value, and the application is filed according to law.

The present invention can be modified in various ways by those skilled in the art without departing from the protection scope of the appended claims.

Claims (12)

1. power-switching circuit, it receives a direct current voltage, comprises at least:

One flyback DC-to-DC converter in order to receiving this direct voltage, and converts this direct voltage to a fixing high-voltage dc voltage, and comprises a first order power circuit and a first control circuit;

One capacitor is connected with this flyback DC-to-DC converter, in order to this high-voltage dc voltage is carried out filtering; And

One direct current a-c transducer is connected with this capacitor, in order to filtered this high-voltage dc voltage is converted to alternating voltage output; Wherein the output waveform of this alternating voltage is an imitative sinusoidal wave ac voltage signal;

Wherein when this alternating voltage was zero voltage level, the one first diverter switch element that this first control circuit is controlled this first order power circuit decommissioned.

2. power-switching circuit as claimed in claim 1, wherein this first order power circuit comprises a transformer and a rectification circuit, the primary side of this transformer is connected with this first diverter switch element and receives this direct voltage, in order to according to the action of this first diverter switch element and make this first order power circuit export this high-voltage dc voltage in the primary side induced voltage of this transformer, this rectification circuit is connected with this primary side of this transformer, in order to rectification.

3. power-switching circuit as claimed in claim 2, wherein this flyback DC-to-DC converter also comprises a feedback circuit, this first control circuit is connected with this feedback circuit and this first diverter switch element, this feedback circuit is connected with this rectification circuit, in order to detect this high-voltage dc voltage of this rectification circuit output, and produce a feedback signal to this first control circuit according to this high-voltage dc voltage correspondence, make this first control circuit produce a control signal according to this feedback signal and control this first diverter switch element operation, so that this high-voltage dc voltage meets a scheduled voltage.

4. power-switching circuit as claimed in claim 3, wherein this DC-AC converter comprises a second level power circuit and a second control circuit, and this second level power circuit is connected with this capacitor, and this second control circuit is connected with this second level power circuit.

5. power-switching circuit as claimed in claim 4 is organized the second diverter switch elements wherein this second level power circuit comprises more, and it is subjected to this second control circuit control and conducting or cut-off, this high-voltage dc voltage is converted to this alternating voltage output.

6. power-switching circuit as claimed in claim 1, wherein this DC-AC converter is a full-bridge direct current a-c transducer.

7. portable power supply device comprises at least:

One energy-storage travelling wave tube is in order to provide a direct current voltage;

One power-switching circuit, it is connected with this energy-storage travelling wave tube, and receives this direct voltage, comprises at least:

One flyback DC-to-DC converter in order to receiving this direct voltage, and converts this direct voltage to a fixing high-voltage dc voltage, and comprises a first order power circuit and a first control circuit;

One capacitor is connected with this flyback DC-to-DC converter, in order to this high-voltage dc voltage is carried out filtering; And

One direct current a-c transducer is connected with this capacitor, in order to filtered this high-voltage dc voltage is converted to alternating voltage output; Wherein the output waveform of this alternating voltage is an imitative sinusoidal wave ac voltage signal;

Wherein when this alternating voltage was zero voltage level, the one first diverter switch element that this first control circuit is controlled this first order power circuit decommissioned.

8. portable power supply device as claimed in claim 7, wherein this first order power circuit comprises a transformer and a rectification circuit, the primary side of this transformer is connected with this first diverter switch element and receives this direct voltage, in order to according to the action of this first diverter switch element and make this first order power circuit export this high-voltage dc voltage in the primary side induced voltage of this transformer, this rectification circuit system is connected with this primary side of this transformer, in order to rectification.

9. portable power supply device as claimed in claim 8, wherein this flyback DC-to-DC converter also comprises a feedback circuit, this first control circuit is connected with this feedback circuit and this first diverter switch element, this feedback circuit is connected with this rectification circuit, in order to detect this high-voltage dc voltage of this rectification circuit output, and produce a feedback signal to this first control circuit according to this high-voltage dc voltage correspondence, make this first control circuit produce a control signal according to this feedback signal and control this first diverter switch element operation, so that this high-voltage dc voltage meets a scheduled voltage.

10. portable power supply device as claimed in claim 9, wherein this DC-AC converter comprises a second level power circuit and a second control circuit, this second level power circuit is connected with this capacitor, and this second control circuit is connected with this second level power circuit.

11. portable power supply device as claimed in claim 10, wherein this second level power circuit comprises many group the second diverter switch elements, and it is subjected to this second control circuit control and conducting or cut-off, this high-voltage dc voltage is converted to this alternating voltage output.

12. portable power supply device as claimed in claim 7, wherein this DC-AC converter is a full-bridge direct current a-c transducer.

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