CN204761281U - A charging device for condenser - Google Patents

Abstract

The utility model provides a device capable of being connected to a power supply voltage source, which comprises: an intermediate circuit (120) comprising a diode bridge, and the diode bridge is configured to rectify the current entering the intermediate circuit from the power supply voltage source; A switch (104) between the supply voltage source and the intermediate circuit (120); a charging circuit arranged to electrically conduct a charging voltage from the supply voltage source to the intermediate circuit (120) in order to charge at least two capacitors , the charging voltage is arranged to be at least partially turned on at the switch (104); the intermediate circuit includes at least two capacitors (240), and the charging circuit is arranged to turn on the charging voltage between the at least two capacitors (240).

Description

Charging device for capacitors

technical field

The utility model relates to a charging device for a capacitor.

Background technique

Inverters are used in the field of electronics to convert direct voltage into alternating voltage. Inverters are used, for example, in portable, battery-operated electrical consumers, in solar-powered products and in electronic systems where it is generally necessary to generate AC voltage from DC voltage. Some inverters can also convert AC voltage to DC voltage, which is called rectification. Three-phase inverters can be used in AC motors.

In addition to or as an additional power source to the battery, the DC power source used by the inverter may, for example, include a solar collector generating DC current. In larger systems, the DC source can be a three-phase current distribution network.

An inverter can be used to vary the frequency of an alternating current by first rectifying the alternating voltage, which is then fed from the rectifier into an inverter which converts it into an alternating voltage having a different frequency. According to the above method, rectification can be performed using, for example, a diode-based rectifier (diode rectifier). The diodes in the diode rectifier may comprise, for example, silicon diodes or Schottky diodes.

For example, an inverter fed by a diode rectifier can have a large DC capacitor, where it is beneficial to charge the DC capacitor to a value equal to the mains voltage, more precisely before switching on the main switch or main contactor, so that, The turn-on operation does not cause large switching current spikes. Large switching current spikes can trip the fuses of the system or disturb the power supply network.

The charging of the DC capacitor can take place via (for example two-phase or three-phase) charging resistors. Resistors are sized individually and there will be losses in them for a good end result. Alternatively a saturable transformer can be used for charging. Due to the large charging current, the saturable transformer must be carefully sized.

Utility model content

The utility model provides a technical solution, whereby the DC capacitor can be charged with less loss, wherein the selection of the parameters of the charging circuit is not as important as the working phase when charging with passive resistors. With the aid of the solution according to the invention, it is possible to use as charging voltage a voltage which is less than half the voltage of the solution based on a saturable transformer of the prior art.

The utility model proposes a device that can be connected with a power supply voltage source, which includes:

an intermediate circuit comprising a diode bridge arranged to rectify a current entering the intermediate circuit from the supply voltage source;

a switch between the supply voltage source and the intermediate circuit;

a charging circuit arranged to electrically conduct a charging voltage from the supply voltage source to the intermediate circuit for charging at least two capacitors, the charging voltage being arranged to be at least partially conductive at the switch;

It is characterized in that the intermediate circuit comprises at least two capacitors, and the charging circuit is arranged to connect a charging voltage between the at least two capacitors.

According to an embodiment of the present invention, the charging circuit includes a single-phase saturable transformer.

According to an embodiment of the present invention, the secondary voltage of the single-phase saturable transformer is about half of the primary voltage.

According to an embodiment of the present invention, a multiplier is formed by the diode bridge, the secondary part of the single-phase saturable transformer and the at least two capacitors, and the multiplier converts the The charging voltage is doubled.

According to an embodiment of the present invention, the charging circuit includes a saturable transformer capable of being electrically separated.

According to an embodiment of the present invention, the secondary voltage of the electrically separable saturable transformer is about half of the primary voltage.

According to an embodiment of the invention, the diode bridge, the secondary part of the electrically separable saturable transformer and the at least two capacitors form a multiplier which connects the intermediate circuit doubles the charging voltage.

According to an embodiment of the invention, the two capacitors comprised in said intermediate circuit are connected in series.

Description of drawings

Figures 1A and 1B show two examples of charging circuits;

2A and 2B show two examples of the charging circuit of the present invention.

Detailed ways

In FIG. 1A a charging circuit is shown with a resistor 110 placed in the two phase lines. In the example shown in the figure, the number of resistors 110 is two, so that the switch 106 can turn off or turn on the charging circuit. The charging circuit shown in the figure may also include four blown fuses 112 in addition to the resistors. Alternatively, the resistor 110 can also be provided in the three-phase line. The main switch 104 serves to switch on a direct current in an inductor 108 , via which a direct current can be fed into an intermediate circuit 120 . In the intermediate circuit 120 a direct current is switched in the manner shown in the figure in a diode bridge connected in parallel with the capacitor 120 . For example, a direct current in an inverter not shown in FIG. 1A can be switched via the intermediate circuit 120 .

In the charging circuit shown in FIG. 1A , the size of the resistor needs to be determined according to each situation, which will increase the working cost of planning the circuit. When sizing, it must be taken into account that the resistor will be used repeatedly in a location where many recharges may be required, and that the resistor may be overloaded with repeated use. In addition, a loss occurs in the charging resistor 110 in the charging circuit of FIG. 1A , which is not an ideal state.

When using the charging circuit of FIG. 1A , the capacitor 122 of the intermediate circuit will be charged to the magnitude of the total voltage by turning the switch 106 on. Then switch 106 is opened, and switch 104 is turned on.

FIG. 1B shows a charging circuit in which a saturable transformer 160 is connected to a single-phase diode rectifier 170 . The single-phase diode rectifier 170 is connected directly to the intermediate circuit 120 in the manner shown in the figure. Elements 104, 108, 120, and 122 in FIG. 1B are substantially the same as corresponding elements in FIG. 1A.

The switch 150 can separate the saturable transformer 160 and the single-phase diode rectifier 170 from the mains voltage. The charging circuit of FIG. 1B may also include a blown fuse 140 .

The charging transformer 160 in the charging circuit of FIG. 1B is saturated first, and thus limits the magnitude of the charging current. As the DC voltage rises, the voltage difference becomes smaller and the charging current is thus limited until, when the capacitor 122 of the intermediate circuit is fully charged, the charging current practically disappears.

When using the charging circuit of FIG. 1B , the switch 150 is turned on. Then switch 150 is turned on, and switch 140 is turned on.

Fig. 2A shows an embodiment of the charging circuit of the present invention. Elements 104, 108, 120, and 122 in FIG. 2A are substantially the same as corresponding elements in FIG. 1A.

The charging circuit of FIG. 2A has a saturable single-phase transformer 220 and uses a diode bridge in the DC intermediate circuit 120 as a rectifier. In DC link circuit 120 two capacitors 240 are connected in series in such a way that a single-phase voltage is passed between them. The single-phase voltage is connected through a saturable single-phase transformer 220 . In this way, the diode bridge, the secondary part of the transformer and the capacitor 240 connected in series form a multiplier which doubles the charging voltage in the intermediate circuit. In this way, the size of the secondary part of the transformer 22 can be up to half the total voltage of the supply voltage source. The charging circuit of FIG. 2B may also include blown fuses 212 and 210 .

The switch 230 in FIG. 2A can separate the transformer 220 from the mains voltage and from the DC intermediate circuit 120 . When switch 230 is open and switch 104 is closed, the total voltage can only be connected to DC link circuit 120 directly via inductance 108 .

A second embodiment of the charging circuit of the present invention is shown in FIG. 2B. Elements 104, 108, 120, and 122 in FIG. 2B are substantially the same as corresponding elements in FIG. 1A, and elements 120 and 240 are substantially the same as corresponding elements in FIG. 2A.

The difference between FIG. 2B and FIG. 2A is that the electrically separable saturable transformer 250 replaces the single-phase saturable transformer 220 to function as a transformer. As shown in FIGS. 2A and 2B , in the DC link circuit 120 two capacitors 240 are connected in series in such a way that a single-phase voltage is passed between them. The single-phase voltage is connected via a saturable transformer 250 which can be electrically separated. In this way, the diode bridge, the secondary part of the transformer and the capacitor 240 connected in series form a multiplier which doubles the charging voltage in the intermediate circuit. In this way, the size of the secondary part of the transformer 22 can be up to half the total voltage of the supply voltage source.

An advantage of the charging circuit of FIGS. 2A and 2B is that the charging circuit can be more easily sized than a passive resistor based charging circuit. Another advantage is that no direct resistive losses occur in the charging circuit as in the charging resistor.

At least in some charging circuits according to embodiments of the present invention, charging can be performed with relatively small losses, and during the charging process, the voltage of the charging transformer can be maintained at half of the voltage of the power supply network. This makes it easier to limit the charging current at the start of charging.

The embodiments of the utility model are not limited to the content described above, and it is obvious to those skilled in the art that the technical variations of the above technical solutions can realize the utility model, and all are within the protection scope of the utility model.

The technical solution of the utility model described above uses specified electronic components. However, those skilled in the art should be clear that other elements can also be used based on the technical concept of the present utility model, and produce the same technical effect as the elements described above.

Claims (8)

1. A device connectable to a supply voltage source comprising: an intermediate circuit (120) comprising a diode bridge arranged to rectify a current entering the intermediate circuit from the supply voltage source; a switch (104) between said supply voltage source and said intermediate circuit (120); a charging circuit arranged to electrically conduct a charging voltage from said supply voltage source to said intermediate circuit (120) for charging at least two capacitors, said charging voltage being arranged at least partially between said switches ( 104) place conduction; It is characterized in that the intermediate circuit comprises at least two capacitors (240), and the charging circuit is configured to switch on a charging voltage between the at least two capacitors (240). 2. The device of claim 1, wherein the charging circuit comprises a single-phase saturable transformer. 3. The arrangement as claimed in claim 2, characterized in that the secondary voltage of the single-phase saturable transformer is approximately half the primary voltage. 4. The device according to claim 2 or 3, characterized in that a multiplier is formed by the diode bridge, the secondary part of the single-phase saturable transformer and the at least two capacitors (240) , the doubler doubles the charging voltage in the intermediate circuit. 5. The apparatus of claim 1, wherein the charging circuit comprises a saturable transformer capable of being electrically separated. 6. The arrangement as claimed in claim 5, characterized in that the secondary voltage of the electrically separable saturable transformer is approximately half the primary voltage. 7. The device according to claim 5 or 6, characterized in that it is formed by the diode bridge, the secondary part of the electrically separable saturable transformer and the at least two capacitors (240) A multiplier that doubles the charging voltage in the intermediate circuit. 8. Arrangement according to claim 1, 2, 3, 5 or 6, characterized in that the two capacitors (240) comprised in the intermediate circuit are connected in series.