Three-level uncontrolled rectifying circuit

Abstract

The utility model provides a three-level uncontrolled rectifying circuit. The three-level uncontrolled rectifying circuit comprises a rectifier, a positive direct-current bus, a negative direct-current bus, a first direct-current bus capacitor, a second direct-current bus capacitor, a first switching switch, a second switching switch, a first discharging resistor, a second discharging resistor, a first bus voltage detection unit and a second bus voltage detection unit. According to the three-level uncontrolled rectification circuit provided by the invention, the problem that the direct current bus is unbalanced under the uncontrolled rectification of the existing three-level rectifier is solved, and the fault rate of the whole machine is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of converter, in particular to a three-level uncontrolled rectifier circuit. BACKGROUND

[0002] The existing three-level rectifier, due to the difference of bus capacitance between the positive and negative DC bus or the difference of load, causes the imbalance of positive and negative DC bus in uncontrolled rectification state, which easily triggers the imbalance of positive and negative DC bus, overvoltage of DC bus and other faults.

[0003] Therefore, it is necessary to provide a circuit containing three-level uncontrolled rectification function, which can solve the imbalance problem of three-level uncontrolled rectifier under uncontrolled rectification. CONTENT OF THE INVENTION

[0004] The present application provides a three-level uncontrolled rectifier circuit to solve the imbalance problem of the existing three-level rectifier under uncontrolled rectification.

[0005] The present application provides a three-level uncontrolled rectifier circuit, which comprises a rectifier, a positive DC bus, a negative DC bus, a first DC bus capacitor, a second DC bus capacitor, a first switching switch, a second switching switch, a first discharge resistor, a second discharge resistor, a first bus voltage detection unit and a second bus voltage detection unit.

[0006] The positive DC end of the rectifier is connected with the positive DC bus, and the negative DC end of the rectifier is connected with the negative DC bus.

[0007] One end of the first DC bus capacitor is connected with the positive DC bus, and the other end of the first DC bus capacitor is connected with the midpoint end of the rectifier. One end of the second DC bus capacitor is connected with the midpoint end of the rectifier, and the other end of the second DC bus capacitor is connected with the negative DC bus.

[0008] The first switching switch is connected in series with the first discharge resistor and then connected in parallel with the first DC bus capacitor. The second switching switch is connected in series with the second discharge resistor and then connected in parallel with the second DC bus capacitor.

[0009] The first bus voltage detection unit is connected in parallel with the first DC bus capacitor, and the second bus voltage detection unit is connected in parallel with the second DC bus capacitor.

[0010] In an example, a controller is further included for controlling the conduction or disconnection of the first switching switch or the second switching switch.

[0011] In an example, the controller is configured to:

[0012] When the voltage detected by the first bus voltage detection unit is greater than a first set value or the difference between the voltage detected by the first bus voltage detection unit and the voltage detected by the second bus voltage detection unit is greater than a second set value, the first switching switch is controlled to be turned on.

[0013] When the voltage detected by the second bus voltage detection unit is greater than a third set value or the difference between the voltage detected by the second bus voltage detection unit and the voltage detected by the first bus voltage detection unit is greater than a fourth set value, the second switching switch is controlled to be turned on.

[0014] In an example, the rectifier has a two-phase AC terminal or a three-phase AC terminal.

[0015] In an example, the first switching switch comprises one of a three-phase circuit breaker, a three-phase contactor, a three-phase load switch, a two-phase circuit breaker, a two-phase contactor, a two-phase load switch, a single-phase circuit breaker, a single-phase contactor, and a single-phase load switch.

[0016] In an example, the second switching switch comprises one of a three-phase circuit breaker, a three-phase contactor, a three-phase load switch, a two-phase circuit breaker, a two-phase contactor, a two-phase load switch, a single-phase circuit breaker, a single-phase contactor, and a single-phase load switch.

[0017] In an example, the first discharging resistor comprises one of:

[0018] one resistor, a plurality of series-connected resistors, and a plurality of parallel-connected resistors.

[0019] In an example, the second discharging resistor comprises one of:

[0020] one resistor, a plurality of series-connected resistors, and a plurality of parallel-connected resistors.

[0021] In an example, the first DC bus capacitor comprises one of:

[0022] one capacitor, a plurality of series-connected capacitors, and a plurality of parallel-connected capacitors.

[0023] In an example, the second DC bus capacitor comprises one of:

[0024] one capacitor, a plurality of series-connected capacitors, and a plurality of parallel-connected capacitors.

[0025] The three-level non-controlled rectifier circuit provided in the present application solves the problem of unbalanced DC bus voltage of the existing three-level rectifier under non-controlled rectification, and reduces the failure rate of the entire machine. BRIEF DESCRIPTION OF DRAWINGS

[0026] One or more embodiments are illustrated by way of example in the figures that are part of this disclosure and which are not intended to limit the scope of the embodiments, the same reference notations in the various figures refer to identical elements, and one skilled in the art will recognize that the figures are not necessarily drawn to scale, the figures in the drawings do not constitute a limitation on the scope of the present disclosure.

[0027] Figure 1 is a schematic diagram of a three-level uncontrolled rectifier circuit provided by an embodiment of the present application;

[0028] Figure 2 is a schematic diagram of a three-level uncontrolled rectifier circuit provided by another embodiment of the present application. DETAILED DESCRIPTION

[0029] In order to facilitate the understanding of the present application, the present application will be described in more detail below in conjunction with the drawings and specific embodiments. Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one skilled in the art to which the present application belongs. The terms used in the present application are only for the purpose of describing specific embodiments of the present application and are not intended to limit the present application. The term "and / or" used in the present application includes any and all combinations of one or more related listed items.

[0030] As shown in Figure 1 , an embodiment of the present application provides a three-level uncontrolled rectifier circuit, which includes a rectifier, a positive DC bus, a negative DC bus, a first DC bus capacitor C1, a second DC bus capacitor C2, a first switching switch K1, a second switching switch K2, a first discharge resistor R1, a second discharge resistor R2, a first bus voltage detection unit, and a second bus voltage detection unit.

[0031] The positive DC end BUS_P of the rectifier is connected to the positive DC bus, and the negative DC end BUS_N of the rectifier is connected to the negative DC bus.

[0032] One end of the first DC bus capacitor C1 is connected to the positive DC bus, the other end of the first DC bus capacitor C1 is connected to the midpoint end BUS_O of the rectifier, one end of the second DC bus capacitor C2 is connected to the midpoint end BUS_O of the rectifier, and the other end of the second DC bus capacitor C2 is connected to the negative DC bus.

[0033] The first switching switch K1 is connected in series with the first discharge resistor R1 and then connected in parallel with the first DC bus capacitor C1, and the second switching switch K2 is connected in series with the second discharge resistor R2 and then connected in parallel with the second DC bus capacitor C2.

[0034] The first bus voltage detection unit is connected in parallel with the first DC bus capacitor C1, and the second bus voltage detection unit is connected in parallel with the second DC bus capacitor C2.

[0035] In an example, a controller is further included for controlling the turn-on or turn-off of the first switching switch K1 or the second switching switch K2.

[0036] In an example, the rectifier has two-way AC terminals.

[0037] In an example, the first switching switch K1 includes one of a three-phase circuit breaker, a three-phase contactor, a three-phase load switch, a two-phase circuit breaker, a two-phase contactor, a two-phase load switch, a single-phase circuit breaker, a single-phase contactor, and a single-phase load switch.

[0038] In an example, the second switching switch K2 includes one of a three-phase circuit breaker, a three-phase contactor, a three-phase load switch, a two-phase circuit breaker, a two-phase contactor, a two-phase load switch, a single-phase circuit breaker, a single-phase contactor, and a single-phase load switch.

[0039] In an example, the first discharging resistor R1 includes one of a single resistor, a plurality of series-connected resistors, and a plurality of parallel-connected resistors.

[0040] In an example, the second discharging resistor R2 includes one of a single resistor, a plurality of series-connected resistors, and a plurality of parallel-connected resistors.

[0041] In an example, the first DC bus capacitor C1 includes one of a single capacitor, a plurality of series-connected capacitors, and a plurality of parallel-connected capacitors.

[0042] In an example, the second DC bus capacitor C2 includes one of a single capacitor, a plurality of series-connected capacitors, and a plurality of parallel-connected capacitors.

[0043] The working process of the three-level uncontrolled rectifier circuit shown in FIG. 1 is described as follows: Figure 1

[0044] 1. If the voltage detected by the first bus voltage detection unit is greater than a first set value, the first switching switch K1 is controlled to be turned on; or if the difference between the voltage detected by the first bus voltage detection unit and the voltage detected by the second bus voltage detection unit is greater than a second set value, the first switching switch K1 is controlled to be turned on.

[0045] 2. If the voltage detected by the second bus voltage detection unit is greater than a third set value, the second switching switch K2 is controlled to be turned on; or if the difference between the voltage detected by the second bus voltage detection unit and the voltage detected by the first bus voltage detection unit is greater than a fourth set value, the second switching switch K2 is controlled to be turned on.

[0046] The first set value to the fourth set value described above can be set according to actual requirements. ​

[0047] Figure 2 is another embodiment of the present application provides a three-level uncontrolled rectifier circuit, and Figure 1 Different from the example, the rectifier has three AC terminals.

[0048] The working process of the three-level uncontrolled rectifier circuit shown in Figure 2 is described below:

[0049] 1. If the voltage detected by the first bus voltage detection unit is greater than the first set value, the first switching switch K1 is controlled to be turned on; or, if the difference between the voltage detected by the first bus voltage detection unit and the voltage detected by the second bus voltage detection unit is greater than the second set value, the first switching switch K1 is controlled to be turned on.

[0050] 2. If the voltage detected by the second bus voltage detection unit is greater than the third set value, the second switching switch K2 is controlled to be turned on; or, if the difference between the voltage detected by the second bus voltage detection unit and the voltage detected by the first bus voltage detection unit is greater than the fourth set value, the second switching switch K2 is controlled to be turned on.

[0051] The first set value to the fourth set value can be set according to actual needs.

[0052] The three-level uncontrolled rectifier circuit provided by the present application balances the voltage of the three-level bus by controlling the switching switch to be turned on when the voltage of the three-level bus is unbalanced under uncontrolled rectification, solves the problem of unbalanced three-level bus under uncontrolled rectification, and reduces the failure rate of the whole machine.

[0053] It should be noted that the present application provides a preferred embodiment of the present application, but the present application can be implemented in many different forms, and is not limited to the embodiments described in the specification, and the embodiments are not additional limitations on the content of the present application. The purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive. And, the above technical features continue to be combined with each other, forming various embodiments not listed above, which are considered to be within the scope of the present application. Furthermore, for those skilled in the art, the above description can be improved or changed, and all these improvements and changes should be within the scope of the appended claims.

Claims

1. A three-level uncontrolled rectifier circuit, characterized by The rectifier, the positive direct current bus, the negative direct current bus, the first direct current bus capacitor, the second direct current bus capacitor, the first switching switch, the second switching switch, the first discharge resistor, the second discharge resistor, the first bus voltage detection unit and the second bus voltage detection unit are connected in series. The positive direct current end of the rectifier is connected with the positive direct current bus, and the negative direct current end of the rectifier is connected with the negative direct current bus. One end of the first direct current bus capacitor is connected with the positive direct current bus, and the other end of the first direct current bus capacitor is connected with the midpoint end of the rectifier. One end of the second direct current bus capacitor is connected with the midpoint end of the rectifier, and the other end of the second direct current bus capacitor is connected with the negative direct current bus. The first switching switch is connected in series with the first discharge resistor and then connected in parallel with the first direct current bus capacitor. The second switching switch is connected in series with the second discharge resistor and then connected in parallel with the second direct current bus capacitor. The first bus voltage detection unit is connected in parallel with the first direct current bus capacitor, and the second bus voltage detection unit is connected in parallel with the second direct current bus capacitor.

2. The three-level uncontrolled rectification circuit according to claim 1, characterized in that, A controller is further included for controlling the conduction or disconnection of the first switching switch or the second switching switch.

3. The three-level uncontrolled rectification circuit according to claim 2, characterized in that, The controller is used for: controlling the conduction of the first switching switch when the voltage detected by the first bus voltage detection unit is greater than a first set value or the difference between the voltage detected by the first bus voltage detection unit and the voltage detected by the second bus voltage detection unit is greater than a second set value; controlling the conduction of the second switching switch when the voltage detected by the second bus voltage detection unit is greater than a third set value or the difference between the voltage detected by the second bus voltage detection unit and the voltage detected by the first bus voltage detection unit is greater than a fourth set value.

4. The three-level uncontrolled rectification circuit according to claim 1, characterized by The rectifier has two-way AC terminals or three-way AC terminals.

5. The three-level uncontrolled rectification circuit according to claim 1, characterized by The first switching switch includes one of a three-phase circuit breaker, a three-phase contactor, a three-phase load switch, a two-phase circuit breaker, a two-phase contactor, a two-phase load switch, a single-phase circuit breaker, a single-phase contactor and a single-phase load switch.

6. The three-level uncontrolled rectification circuit according to claim 1, characterized by The second switching switch includes one of a three-phase circuit breaker, a three-phase contactor, a three-phase load switch, a two-phase circuit breaker, a two-phase contactor, a two-phase load switch, a single-phase circuit breaker, a single-phase contactor and a single-phase load switch.

7. The three-level uncontrolled rectification circuit according to claim 1, characterized by The first discharge resistor includes one of: one resistor, a plurality of series-connected resistors and a plurality of parallel-connected resistors.

8. The three-level uncontrolled rectification circuit according to claim 1, characterized by The second discharge resistor includes one of: one resistor, a plurality of series-connected resistors and a plurality of parallel-connected resistors.

9. The three-level, uncontrolled rectification circuit of claim 1, wherein, The first direct current bus capacitor includes one of: one capacitor, a plurality of series-connected capacitors and a plurality of parallel-connected capacitors.

10. The three-level uncontrolled rectification circuit according to claim 1, characterized by The second direct current bus capacitor includes one of: one capacitor, a plurality of series-connected capacitors and a plurality of parallel-connected capacitors.

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