Circuit unit and power conversion device comprising same

Abstract

The application proposes a circuit unit, and the circuit unit comprises a single-pole double-throw relay which comprises a common end, a normally-closed contact, and a normally-open contact; the switch resistor series branch comprises a first switch unit and a resistor unit which are connected in series, the first end of the switch resistor series branch is connected with the normally-closed contact, the second end of the switch resistor series branch is connected with the normally-open contact, the common end of the single-pole double-throw relay is used for being connected with a power supply circuit, and the common end of the single-pole double-throw relay is used for being connected with the normally-open contact. The second end of the switch resistor series branch is used for being connected with a power conversion circuit, and the output end of the power conversion circuit comprises a bus capacitor.

Description

Technical Field

[0001] The present application relates to the field of power supply, and in particular to a circuit unit and a power conversion device comprising the same. Background Art

[0002] With the development of power supply technology, higher requirements are placed on power conversion devices.

[0003] For example, the reliability of the electronic components inside the power conversion device and the stability of the power supply both affect the reliability of the power conversion device.

[0004] High reliability is one of the important indicators of power conversion devices, so how to design a high reliability power conversion device has become the focus of research in the industry. Summary of the invention

[0005] The present application proposes a circuit unit, including: a single-pole double-throw relay, including a common end, a normally closed contact and a normally open contact; a switch resistor series branch, including a first switch unit and a resistor unit connected in series, the first end of the switch resistor series branch is connected to the normally closed contact, and the second end of the switch resistor series branch is connected to the normally open contact, wherein the common end of the single-pole double-throw relay is used to connect a power supply circuit, and the second end of the switch resistor series branch is used to connect a power conversion circuit, and the output end of the power conversion circuit includes a bus capacitor.

[0006] Furthermore, it also includes: a second switch unit connected between the common end of the single-pole double-throw relay and the second end of the switch resistor series branch.

[0007] Furthermore, the power supply circuit is a power source.

[0008] Furthermore, the power supply circuit includes: a relay switching unit, including at least one relay, having a first input end, a second input end and an output end, the first input end is used to connect to a first power source, the second input end is used to connect to a second power source, and the output end is connected to a common end of the single-pole double-throw relay.

[0009] Furthermore, the first switch unit is a thyristor, a MOS tube or a relay.

[0010] Furthermore, the second switch unit is a thyristor, a MOS tube or a relay.

[0011] The present application also provides a power conversion device, including: a relay switching unit, including at least one relay, having a first input end, a second input end and an output end, the first input end is used to connect to a first power source, and the second input end is used to connect to a second power source; a single-pole double-throw relay, including a common end, a normally closed contact and a normally open contact, the output end of the relay switching unit is connected to the common end of the single-pole double-throw relay; a switch resistor series branch, including a first switch unit and a resistor unit connected in series, the first end of the switch resistor series branch is connected to the normally closed contact, and the second end of the switch resistor series branch is connected to the normally open contact; a second switch unit is connected between the common end of the single-pole double-throw relay and the second end of the switch resistor series branch; a power conversion circuit, the input end of which is connected to the second end of the switch resistor series branch, wherein the output end of the power conversion circuit includes a bus capacitor; a control circuit, used to output a control signal for controlling the single-pole double-throw relay, the first switch unit, and the second switch unit.

[0012] Furthermore, when the power is turned on, the control circuit is configured to output a control signal so that the first switch unit is turned on, the second switch unit is turned off, and the common end of the single-pole double-throw relay is connected to the normally closed contact of the single-pole double-throw relay; when the voltage of the bus capacitor is charged to a predetermined value, the control circuit is configured to output a control signal so that the first switch unit and the second switch unit are turned off, and the common end of the single-pole double-throw relay is connected to the normally open contact of the single-pole double-throw relay.

[0013] Furthermore, during the operation of the power conversion device, and when it is necessary to switch between the first power source and the second power source, the control circuit is configured to output a control signal: turning on the second switch unit and turning off the first switch unit; simultaneously or subsequently switching the common end of the single-pole double-throw relay from the normally open contact connected to the single-pole double-throw relay to the normally closed contact; then turning off the second switch unit; simultaneously or subsequently switching between the first power source and the second power source; then turning on the second switch unit; simultaneously or subsequently switching the common end of the single-pole double-throw relay from the normally closed contact connected to the single-pole double-throw relay to the normally open contact; then turning off the second switch unit.

[0014] The present application also provides a power conversion device, including: a relay switching unit, including at least one relay, having a first input end, a second input end and an output end, the first input end is used to connect to a first power source, and the second input end is used to connect to a second power source; a single-pole double-throw relay, including a common end, a normally closed contact and a normally open contact, the output end of the relay switching unit is connected to the common end of the single-pole double-throw relay; a switch resistor series branch, including a first switch unit and a resistor unit connected in series, the first end of the switch resistor series branch is connected to the normally closed contact, and the second end of the switch resistor series branch is connected to the normally open contact; a power conversion circuit, the input end of which is connected to the second end of the switch resistor series branch, wherein the output end of the power conversion circuit includes a bus capacitor; a control circuit, used to output a control signal for controlling the single-pole double-throw relay, the first switch unit, and the power conversion circuit.

[0015] Furthermore, when the power is turned on, the control circuit is configured to output a control signal so that: the first switch unit is turned on and the common end of the single-pole double-throw relay is connected to the normally closed contact of the single-pole double-throw relay; when the voltage of the bus capacitor is charged to a predetermined value, the control circuit is configured to output a control signal so that: the first switch unit is turned off and the common end of the single-pole double-throw relay is connected to the normally open contact of the single-pole double-throw relay.

[0016] Furthermore, during the operation of the power conversion device, and when it is necessary to switch between the first power source and the second power source, the control circuit is configured to output a control signal: causing the first switch unit to be turned off and the power conversion circuit to not operate; simultaneously or subsequently causing the common end of the single-pole double-throw relay to be switched from a normally open contact connected to the single-pole double-throw relay to a normally closed contact; simultaneously or subsequently causing switching between the first power source and the second power source; simultaneously or subsequently causing the common end of the single-pole double-throw relay to be switched from a normally closed contact connected to the single-pole double-throw relay to a normally open contact; and then causing the power conversion circuit to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 FIG. 1 is a schematic diagram of a circuit unit according to an embodiment of the present application.

[0018] Figure 2 This is a schematic diagram of a circuit unit according to another embodiment of the present application.

[0019] Figure 3 An embodiment of the present application includes Figure 1 Schematic diagram of the power conversion device of the circuit unit in FIG.

[0020] Figure 4 Another embodiment of the present application includes Figure 2 Schematic diagram of the power conversion device of the circuit unit in FIG.

[0021] Figure 5 For an embodiment of the present application Figure 3 Schematic diagram of control waveform when the power conversion device in FIG. 1 is turned on.

[0022] Figure 6 For an embodiment of the present application Figure 3 Schematic diagram of control waveform when the power conversion device in the embodiment performs power supply end switching.

[0023] Figure 7 For an embodiment of the present application Figure 4 Schematic diagram of control waveform when the power conversion device in FIG. 1 is turned on.

[0024] Figure 8 For an embodiment of the present application Figure 4 Schematic diagram of control waveform when the power conversion device in the embodiment performs power supply end switching. DETAILED DESCRIPTION

[0025] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] In one embodiment of the present application, a circuit unit is provided. Figure 1 The circuit unit schematic diagram of an embodiment of the present application is shown, and the circuit unit includes:

[0027] The single-pole double-throw relay Rc includes a common terminal 1, a normally closed contact 2 and a normally open contact 3;

[0028] The switch resistor series branch 120 includes a first switch unit S1 and a resistor unit R connected in series. The first end of the switch resistor series branch 120 is connected to the normally closed contact 2, and the second end of the switch resistor series branch 120 is connected to the normally open contact 3.

[0029] The common terminal 1 of the single-pole double-throw relay Rc is used to connect a power supply circuit 210, and the second end of the switch resistor series branch 120 is used to connect a power conversion circuit 300. The output end of the power conversion circuit 300 includes a bus capacitor Co.

[0030] For further information, see Figure 2The circuit unit schematic diagram of another embodiment of the present application is shown, and the circuit unit also includes: a second switch unit S2 connected between the common terminal 1 of the single-pole double-throw relay Rc and the second end of the switch resistor series branch 120.

[0031] like Figure 1 and Figure 2 As shown, the first switch unit S1 is implemented as a bidirectional thyristor, but the present application does not limit this. As long as the switch tube can be switched between on and off by control, it is applicable to the present application, such as a thyristor, a MOS tube or a relay. The second switch unit S2 is similar to the first switch unit S1 and will not be described in detail here.

[0032] like Figure 1 and Figure 2 As shown, the resistance unit R is implemented as a resistor, but the present application does not limit this. For example, it can also be a thermistor, or it can be formed by connecting multiple resistors in series and in parallel, as long as it exhibits resistance.

[0033] In actual implementation, the power supply circuit 210 can be implemented as a power source, such as a voltage source, which can be an alternating current or a direct current.

[0034] In actual implementation, the power supply circuit 210 can also be implemented as a dual-input power supply. Figure 3 The embodiment of the present application shown includes Figure 1 A schematic diagram of a power conversion device of a circuit unit in FIG. 1 , and Figure 4 Another embodiment of the present application shown includes Figure 2 Schematic diagram of the power conversion device of the circuit unit in FIG. Figure 3 and Figure 4 As shown, the power supply circuit 210 includes: a relay switching unit 210, including at least one relay, having a first input end, a second input end and an output end, the first input end is used to connect to the first power source V1, the second input end is used to connect to the second power source V2, and the output end is connected to the common end 1 of the single-pole double-throw relay Rc.

[0035] For more details, please refer to Figure 3 The power conversion device shown comprises:

[0036] The relay switching unit 210 includes at least one relay, and has a first input end, a second input end, and an output end, wherein the first input end is used to connect to the first power source V1, and the second input end is used to connect to the second power source V2;

[0037] The single-pole double-throw relay Rc includes a common terminal 1, a normally closed contact 2 and a normally open contact 3, and the output end of the relay switching unit 210 is connected to the common terminal 1 of the single-pole double-throw relay Rc;

[0038] The switch resistor series branch 120 includes a first switch unit S1 and a resistor unit R connected in series, a first end of the switch resistor series branch 120 is connected to the normally closed contact 2, and a second end of the switch resistor series branch 120 is connected to the normally open contact 3;

[0039] The power conversion circuit 300 has an input end connected to the second end of the switch resistor series branch 120, wherein the output end of the power conversion circuit 300 includes a bus capacitor Co;

[0040] The control circuit 400 is used to output control signals for controlling the single-pole double-throw relay Rc, the first switch unit S1 , and the power conversion circuit 300 .

[0041] See also Figure 5 shown Figure 3 Schematic diagram of control waveform when the power conversion device is turned on, wherein DRV Rc is a control signal for controlling the single-pole double-throw relay Rc, and DRV S1 is a control signal for controlling the first switch unit S1. Figure 5 As shown, when the power conversion device is turned on, that is, when the power supply circuit 210 starts to provide the input voltage Vin to the power conversion circuit 300, the control circuit 400 is configured to output a control signal so that the first switch unit S1 is turned on and the common terminal 1 of the single-pole double-throw relay Rc is connected to the normally closed contact 2 of the single-pole double-throw relay Rc; when the voltage of the bus capacitor Co is charged to a predetermined value, the control circuit 400 is configured to output a control signal so that the first switch unit S1 is turned off and the common terminal 1 of the single-pole double-throw relay Rc is connected to the normally open contact 3 of the single-pole double-throw relay Rc.

[0042] It can be seen that when the machine is turned on, Figure 5 At time T1 in the figure, by controlling the single-pole double-throw relay Rc and the first switch unit S1, the startup current flows through the common terminal 1 and the normally closed contact 2 of the single-pole double-throw relay Rc and the switch resistor series branch 120, and the resistor unit R suppresses the startup surge current and charges the bus capacitor Co of the power conversion circuit 300. When the voltage of the bus capacitor Co is charged to a predetermined value, as shown in FIG. Figure 5 At time T2, the first switch unit S1 is turned off, and the common terminal 1 of the single-pole double-throw relay Rc is connected to the normally open contact 3 of the single-pole double-throw relay Rc. Then, the current passes through the common terminal 1 and the normally open contact 3 of the single-pole double-throw relay Rc to supply power to the subsequent power conversion circuit 300.

[0043] In actual implementation, the predetermined value of the bus capacitor Co can be set according to different converters, and this application does not limit this.

[0044] like Figure 5 As shown, when the control signal DRV S1 given to the first switch unit S1 is at a high level, it is turned on; when it is at a low level, it is turned off. Figure 5 As shown, when the control signal DRV Rc given to the single-pole double-throw relay Rc is at a high level, the common terminal 1 of the single-pole double-throw relay Rc is connected to the normally open contact 3; when it is at a low level, the common terminal 1 of the single-pole double-throw relay Rc is connected to the normally closed contact 2.

[0045] This method of suppressing inrush current during the startup process is also applicable to the embodiment in which the power supply circuit 210 is implemented as a power source. The principle is the same and will not be described in detail here.

[0046] In actual applications, in situations where continuous operation and power outage are required, in order to prevent power supply abnormalities (such as unstable power supply, power outage, etc.) from causing equipment downtime, many situations will have two different power supply systems backed up for each other, such as: mains power supply and generator power supply, mains power supply and battery power supply, mains power supply and UPS power supply, etc. Figure 3 and Figure 4 The dual-output power conversion device shown in the figure can realize the input redundancy function. In the above-mentioned power consumption scenarios, automatic transfer switches (ATS) are often used to realize the fast load switching of two power supplies, ensure the stable and reliable long-term operation of the power supply and power-consuming equipment, and avoid downtime caused by input abnormalities, resulting in economic losses.

[0047] However, the various solutions currently used in the industry to achieve input redundancy on the same power supply still have major drawbacks. If zero current switching cannot be achieved, arc extinguishing needs to be considered, and relays with arc extinguishing devices need to be used, which results in a large relay size, and also causes great interference to the power supply during load switching, greatly increasing the size and cost of the power supply.

[0048] For this application Figure 3 The power conversion device shown in the figure, during the operation of the power conversion device, if one power supply end fails and needs to switch to another power supply end for power supply, the power conversion device of the present application can realize zero current switching. Figure 6 The present application of an embodiment shown in Figure 3 3 is a control waveform diagram of the power conversion device when switching the power supply end, wherein DRV Rc is a control signal for controlling the single-pole double-throw relay Rc, DRV S1 is a control signal for controlling the first switch unit S1, and DRV P is a control signal for controlling the power conversion circuit 300.

[0049] like Figure 6 As shown, during the operation of the power conversion device, when it is necessary to switch between the first power source V1 and the second power source V2, the control circuit 400 is configured to output a control signal:

[0050] The first switch unit S1 is turned off, and the power conversion circuit 300 does not work;

[0051] At the same time or afterwards, the common terminal 1 of the single-pole double-throw relay Rc is switched from the normally open contact 3 connected to the single-pole double-throw relay Rc to the normally closed contact 2;

[0052] At the same time or afterwards, switching between the first power source V1 and the second power source V2;

[0053] At the same time or afterwards, the common terminal 1 of the single-pole double-throw relay Rc is switched from the normally closed contact 2 connected to the single-pole double-throw relay Rc to the normally open contact 3;

[0054] Then the power conversion circuit 300 is put into operation.

[0055] like Figure 6 As shown, during the operation of the power conversion device, if it is detected that the first power source V1 cannot supply power normally but the second power source V2 can still supply power normally, the first power source V1 needs to be switched to the second power source V2 to provide the input voltage Vin.

[0056] like Figure 6 As shown, at time T1, it is detected that the first power source V1 is powered off, and the control signal to the power conversion circuit 300 is switched to a low level, so that the power conversion circuit 300 stops working, and the first switch unit S1 is in the off state. Since the power conversion circuit 300 is not working and the first switch unit S1 is in the off state, the current flowing through the single-pole double-throw relay Rc is zero. If at this time or later, as Figure 6 As shown, at the subsequent time T2, the control signal to the single-pole double-throw relay Rc is switched to a low level, so that the common terminal 1 of the single-pole double-throw relay Rc is switched from the normally open contact 3 to the normally closed contact 2, thereby achieving zero-current switching of the single-pole double-throw relay Rc, avoiding the arcing problem during relay switching, protecting the relay, and extending its service life without the need for an arc extinguishing device.

[0057] At the same time or later, the first power source V1 and the second power source V2 are switched, such as Figure 6 As shown, the switching between the first power source V1 and the second power source V2 is completed between time T2 and time T3. Figure 3 As shown, the control circuit 400 also outputs a control signal to control the relay switching unit 210, and the relay in the relay switching unit 210 can be controlled to switch from the first power source V1 to the second power source V2. Figure 6As shown, at time T3, the second power source V2 provides the input voltage Vin, that is, the switching between the first power source V1 and the second power source V2 is completed. And as mentioned above, during this period, the first switch unit S1 is turned off, and the power conversion circuit 300 does not work, so the zero current switching between the first power source V1 and the second power source V2 can be achieved, and the surge current when the input two paths are switched can be reduced, thereby improving the reliability of the power conversion device.

[0058] Afterwards or at the same time, the common terminal 1 of the single-pole double-throw relay Rc is switched from the normally closed contact 2 connected to the single-pole double-throw relay Rc to the normally open contact 3. Figure 6 As shown, at time T3, the common terminal 1 of the single-pole double-throw relay Rc is switched from the normally closed contact 2 connected to the single-pole double-throw relay Rc to the normally open contact 3. As can be seen from the above analysis, zero-current switching of the single-pole double-throw relay Rc can also be achieved.

[0059] Then the power conversion circuit 300 is operated. Figure 6 As shown, at time T4, the power conversion circuit 300 is operated to ensure zero current switching of the single-pole double-throw relay Rc at time T3.

[0060] From the above description, we can see that Figure 3 The power conversion device shown can not only realize startup surge suppression, but also realize zero current switching when switching between multiple inputs, thereby improving the reliability of the power conversion device and reducing its size.

[0061] For more details, please refer to Figure 4 The power conversion device shown comprises:

[0062] The relay switching unit 210 includes at least one relay, and has a first input end, a second input end, and an output end, wherein the first input end is used to connect to the first power source V1, and the second input end is used to connect to the second power source V2;

[0063] The single-pole double-throw relay Rc includes a common terminal 1, a normally closed contact 2 and a normally open contact 3, and the output end of the relay switching unit 210 is connected to the common terminal 1 of the single-pole double-throw relay Rc;

[0064] The switch resistor series branch 120 includes a first switch unit S1 and a resistor unit R connected in series, a first end of the switch resistor series branch 120 is connected to the normally closed contact 2, and a second end of the switch resistor series branch 120 is connected to the normally open contact 3;

[0065] The second switch unit S2 is connected between the common terminal 1 of the single-pole double-throw relay Rc and the second end of the switch resistor series branch 120;

[0066] The power conversion circuit 300 has an input end connected to the second end of the switch resistor series branch 120, wherein the output end of the power conversion circuit 300 includes a bus capacitor Co;

[0067] The control circuit 400 is used to output control signals for controlling the single-pole double-throw relay Rc, the first switch unit S1, and the second switch unit S2.

[0068] See also Figure 7 shown Figure 4 Schematic diagram of control waveform when the power conversion device is turned on. Figure 7 As shown, DRV Rc is a control signal for controlling the single-pole double-throw relay Rc, DRV S1 is a control signal for controlling the first switch unit S1, and DRV S2 is a control signal for controlling the second switch unit S2. Figure 7 As shown, when the power conversion device is turned on, the control circuit 400 is configured to output a control signal so that the first switch unit S1 is turned on, the second switch unit S2 is turned off, and the common end 1 of the single-pole double-throw relay Rc is connected to the normally closed contact 2 of the single-pole double-throw relay Rc; when the voltage of the bus capacitor Co is charged to a predetermined value, the control circuit 400 is configured to output a control signal so that the first switch unit S1 and the second switch unit S2 are turned off, and the common end 1 of the single-pole double-throw relay Rc is connected to the normally open contact 3 of the single-pole double-throw relay Rc.

[0069] and Figure 3 and Figure 5 The method is similar, except that the second switch unit S2 is placed in an off state. Since the principle is the same, it will not be described here in detail.

[0070] This inrush current method during the startup process is also applicable to the embodiment where the power supply circuit 210 is implemented as a power source. The principles are the same and will not be described in detail herein.

[0071] Similarly, for Figure 4 In the power conversion device shown, during the operation of the power conversion device, if one power supply end fails and needs to switch to another power supply end for power supply, the power conversion device of the present application can realize zero current switching. Figure 8 The present application of an embodiment shown in Figure 4 Control waveform diagram of the power conversion device when switching the power supply end.

[0072] like Figure 8 As shown, during the operation of the power conversion device, when it is necessary to switch between the first power source V1 and the second power source V2, the control circuit 400 is configured to output a control signal:

[0073] The second switch unit S2 is turned on and the first switch unit S1 is turned off;

[0074] At the same time or afterwards, the common terminal 1 of the single-pole double-throw relay Rc is switched from the normally open contact 3 connected to the single-pole double-throw relay Rc to the normally closed contact 2;

[0075] Then the second switch unit S2 is turned off;

[0076] At the same time or afterwards, switching between the first power source V1 and the second power source V2;

[0077] Then the second switch unit S2 is turned on;

[0078] At the same time or afterwards, the common terminal 1 of the single-pole double-throw relay Rc is switched from the normally closed contact 2 connected to the single-pole double-throw relay Rc to the normally open contact 3;

[0079] Then the second switch unit S2 is turned off.

[0080] like Figure 8 As shown, at time T1, it is detected that the first power source V1 is powered off, so that the first switch unit S1 is in the off state and the second switch unit S2 is switched to the on state, then the second switch unit S2 bypasses the single-pole double-throw relay Rc and the switch resistor series branch 120, and the current flowing through the single-pole double-throw relay Rc is zero. If at this time or later, as Figure 8 As shown, at the subsequent time T2, the control signal to the single-pole double-throw relay Rc is switched to a low level, so that the common terminal 1 of the single-pole double-throw relay Rc is switched from the normally open contact 3 to the normally closed contact 2, thereby achieving zero-current switching of the single-pole double-throw relay Rc, avoiding the arcing problem during relay switching, protecting the relay, and extending its service life without the need for an arc extinguishing device.

[0081] Then as Figure 8 As shown, at the subsequent time T3, the second switch unit S2 is turned off, so that the relay switching unit 210 is disconnected from the subsequent power circuit. At the same time or later, the first power source V1 and the second power source V2 are switched, as shown in FIG. Figure 8 As shown, the switching between the first power source V1 and the second power source V2 is completed between time T3 and time T4. Figure 8 As shown, at time T4, the second power source V2 provides the input voltage Vin, that is, the switching between the first power source V1 and the second power source V2 is completed. And as mentioned above, during this period, the relay switching unit 210 is disconnected from the subsequent power circuit, so that the zero current switching between the first power source V1 and the second power source V2 can be achieved, and the surge current when the input two paths are switched can be reduced, thereby improving the reliability of the power conversion device.

[0082] Then the second switch unit S2 is turned on. Figure 8As shown, at time T4, the second switch unit S2 is turned on, and the second switch unit S2 bypasses the single-pole double-throw relay Rc and the switch resistor series branch 120 again, and the current flowing through the single-pole double-throw relay Rc is zero.

[0083] At the same time or later, the common terminal 1 of the single-pole double-throw relay Rc is switched from the normally closed contact 2 connected to the single-pole double-throw relay Rc to the normally open contact 3. Figure 8 As shown, at the same time, that is, at time T4, the common terminal 1 of the single-pole double-throw relay Rc is switched from the normally closed contact 2 connected to the single-pole double-throw relay Rc to the normally open contact 3. As can be seen from the above analysis, zero current switching of the single-pole double-throw relay Rc is achieved.

[0084] Then the second switch unit S2 is turned off. Figure 8 As shown, at time T5, the second switch unit S2 is turned off, and the common terminal 1 of the single-pole double-throw relay Rc is connected to the normally open contact 3 to supply power to the power conversion circuit 300.

[0085] From the above description, we can see that Figure 3 , Figure 4 Since the power conversion device in the embodiment of the present invention has a second switch unit S2, the single-pole double-throw relay Rc and the switch resistor series branch 120 can be bypassed by the second switch unit S2 to achieve zero current switching of the single-pole double-throw relay Rc. Figure 3 The power conversion device in the power conversion circuit 300 needs to change the working state, so Figure 4 The power conversion device shown has simpler control and higher reliability when switching between different power sources.

[0086] From the above description, we can see that Figure 1 and Figure 2 The power supply unit and the power conversion device using the same can not only realize startup surge suppression, but also realize zero current switching when switching between multiple inputs, thereby improving the reliability of the power conversion device and reducing its size. At the same time, only one switch tube of the first switch unit S1 and the second switch unit S2 is working, so the loss is small.

[0087] In actual implementation, the power source input to the first power supply terminal V1 and the second power supply terminal V2 can be an AC voltage or a DC voltage, and this application does not limit this.

[0088] In actual implementation, the first power supply terminal V1 may be selected as the main input, or the second power supply terminal V2 may be selected as the main input.

[0089] In actual implementation, the power conversion device may further include multiple filter circuits to improve the EMI performance of the power conversion device.

[0090] In actual implementation, the power conversion circuit 300 may be a boost circuit, but the present application does not limit the power conversion circuit 300 and it may be modified according to different application requirements.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A circuit unit, characterized in that: include: A single-pole double-throw relay, including a common terminal, a normally closed contact, and a normally open contact; The switch resistor series branch comprises a first switch unit and a resistor unit connected in series, wherein a first end of the switch resistor series branch is connected to the normally closed contact, and a second end of the switch resistor series branch is connected to the normally open contact. The common end of the single-pole double-throw relay is used to connect a power supply circuit, the second end of the switch resistor series branch is used to connect a power conversion circuit, and the output end of the power conversion circuit includes a bus capacitor.

2. The circuit unit according to claim 1, characterized in that: Also includes: The second switch unit is connected between the common end of the single-pole double-throw relay and the second end of the switch resistor series branch.

3. The circuit unit according to claim 1 or 2, characterized in that: The power supply circuit is a power source.

4. The circuit unit according to claim 1 or 2, characterized in that: The power supply circuit comprises: The relay switching unit comprises at least one relay having a first input end, a second input end and an output end, wherein the first input end is used to connect to a first power source, the second input end is used to connect to a second power source, and the output end is connected to a common end of the single-pole double-throw relay.

5. The circuit unit according to claim 1, characterized in that: The first switch unit is a thyristor, a MOS tube or a relay.

6. The circuit unit according to claim 2, characterized in that: The second switch unit is a thyristor, a MOS tube or a relay.

7. A power conversion device, characterized in that: include: A relay switching unit, comprising at least one relay, having a first input end, a second input end and an output end, wherein the first input end is used to connect to a first power source, and the second input end is used to connect to a second power source; A single-pole double-throw relay comprises a common terminal, a normally closed contact and a normally open contact, wherein the output terminal of the relay switching unit is connected to the common terminal of the single-pole double-throw relay; A switch resistor series branch comprises a first switch unit and a resistor unit connected in series, wherein a first end of the switch resistor series branch is connected to the normally closed contact, and a second end of the switch resistor series branch is connected to the normally open contact; A second switch unit is connected between the common end of the single-pole double-throw relay and the second end of the switch resistor series branch; A power conversion circuit, the input end of which is connected to the second end of the switch resistor series branch, wherein the output end of the power conversion circuit includes a bus capacitor; The control circuit is used to output a control signal for controlling the single-pole double-throw relay, the first switch unit, and the second switch unit.

8. The power conversion device according to claim 7, characterized in that: When the power is turned on, the control circuit is configured to output a control signal so that the first switch unit is turned on, the second switch unit is turned off, and the common end of the single-pole double-throw relay is connected to the normally closed contact of the single-pole double-throw relay; When the voltage of the bus capacitor is charged to a predetermined value, the control circuit is configured to output a control signal so that the first switch unit and the second switch unit are turned off and the common end of the single-pole double-throw relay is connected to the normally open contact of the single-pole double-throw relay.

9. The power conversion device according to claim 7, characterized in that: During the operation of the power conversion device, when it is necessary to switch between the first power source and the second power source, the control circuit is configured to output a control signal: Turning on the second switch unit and turning off the first switch unit; At the same time or afterwards, the common end of the single-pole double-throw relay is switched from a normally open contact connected to the single-pole double-throw relay to a normally closed contact; Then the second switch unit is turned off; Simultaneously or subsequently, switching between the first power source and the second power source; Then, the second switch unit is turned on; At the same time or afterwards, the common terminal of the single-pole double-throw relay is switched from a normally closed contact connected to the single-pole double-throw relay to a normally open contact; Then the second switch unit is turned off.

10. A power conversion device, characterized in that: include: A relay switching unit, comprising at least one relay, having a first input end, a second input end and an output end, wherein the first input end is used to connect to a first power source, and the second input end is used to connect to a second power source; A single-pole double-throw relay comprises a common terminal, a normally closed contact and a normally open contact, wherein the output terminal of the relay switching unit is connected to the common terminal of the single-pole double-throw relay; A switch resistor series branch comprises a first switch unit and a resistor unit connected in series, wherein a first end of the switch resistor series branch is connected to the normally closed contact, and a second end of the switch resistor series branch is connected to the normally open contact; A power conversion circuit, the input end of which is connected to the second end of the switch resistor series branch, wherein the output end of the power conversion circuit includes a bus capacitor; The control circuit is used to output a control signal for controlling the single-pole double-throw relay, the first switch unit, and the power conversion circuit.

11. The power conversion device according to claim 10, characterized in that: When the power is turned on, the control circuit is configured to output a control signal so that: the first switch unit is turned on, and the common end of the single-pole double-throw relay is connected to the normally closed contact of the single-pole double-throw relay; When the voltage of the bus capacitor is charged to a predetermined value, the control circuit is configured to output a control signal so that: the first switch unit is turned off and the common end of the single-pole double-throw relay is connected to the normally open contact of the single-pole double-throw relay.

12. The power conversion device according to claim 10, characterized in that: During the operation of the power conversion device, when it is necessary to switch between the first power source and the second power source, the control circuit is configured to output a control signal: The first switch unit is turned off, and the power conversion circuit does not work; At the same time or afterwards, the common end of the single-pole double-throw relay is switched from a normally open contact connected to the single-pole double-throw relay to a normally closed contact; Simultaneously or subsequently, switching between the first power source and the second power source; At the same time or afterwards, the common terminal of the single-pole double-throw relay is switched from a normally closed contact connected to the single-pole double-throw relay to a normally open contact; Then the power conversion circuit is put into operation.

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