Power converter and UPS (Uninterrupted Power Supply) comprising same
By optimizing the circuit topology of the UPS and using bridge arm control to achieve AC-DC and DC-DC conversion, the problems of low circuit utilization, large size and high cost of existing UPS are solved, and the effect of simple circuit topology, low cost, small size and high circuit utilization is achieved.
Patent Information
- Application Number
- CN202410367301.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-28
- Publication Date
- 2025-09-30
AI Technical Summary
Existing UPSs have low circuit utilization, large size, high cost, and poor stability, making it difficult to achieve efficient AC-DC and DC-DC conversion.
A power converter including a first switch module, a second switch module, and first and second power conversion modules is used to achieve AC-DC and DC-DC conversion by controlling the conduction and disconnection of the bridge arm. A third switch module and a third power conversion module are combined to perform DC-DC conversion, thereby optimizing the circuit topology.
The circuit topology is simple, the cost is low, the volume is small, and the circuit utilization rate is high, which significantly reduces the volume and cost of the UPS and improves the circuit stability and power supply efficiency.
Smart Images
Figure CN120729012A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of electric power supply, and in particular relates to a power converter and an uninterruptible power supply (UPS) comprising the power converter. Background Art
[0002] The statements in this section are merely intended to provide background information related to the present invention to assist in understanding the present invention. Such background information does not necessarily constitute prior art.
[0003] A UPS is used to instantly switch to a backup power source (such as a rechargeable battery) to provide continuous power to the load when the main power source (such as the mains grid) is abnormal, protecting the load from damage caused by power outages. A UPS typically includes an AC-DC converter module (rectifier) that converts AC power to DC power, a DC-AC converter module (inverter) that converts DC power to AC power, a backup power source, a DC-DC converter module (charger) that supplies power to the backup power source, and a DC-DC converter module (battery converter) that converts the backup power source to DC power.
[0004] When the main power fails, the UPS switches the system from main power operation to backup power operation, and then switches from backup power operation to main power operation when the main power resumes working.
[0005] UPS in the prior art usually uses specialized circuit modules to implement functions such as AC-DC conversion, DC-DC conversion, and DC bus balancing, resulting in low circuit utilization, large size, high cost, and poor stability of the entire UPS. Summary of the Invention
[0006] Therefore, the object of the present invention is to overcome the defects of the above-mentioned prior art and provide a power converter, comprising a first switching module and a second switching module and a first power conversion module and a second power conversion module, wherein each of the first power conversion module and the second power conversion module comprises two bridge arms,
[0007] The first switch module is configured to selectively electrically connect the input end of the first power conversion module to the first phase of the AC power supply or the DC power supply.
[0008] The second switch module is configured to selectively electrically connect the input end of the second power conversion module to the second phase of the AC power supply or the DC power supply, and
[0009] The first power conversion module and the second power conversion module are configured so that the two bridge arms perform AC-DC conversion independently of each other, so that the DC bus is powered by the AC power supply; or are configured so that the two bridge arms perform DC-DC conversion in cooperation with each other, so that the DC bus is powered by the DC power supply.
[0010] According to the power converter of the present invention, preferably, it also includes a third switch module and a third power conversion module, wherein the third power conversion module is a DC-DC conversion module, and the third switch module is configured to control the conduction and disconnection between the input end of the third power conversion module and the DC power supply, and the output end of the third power conversion module is electrically connected to the DC bus.
[0011] The power converter according to the present invention preferably includes an overload operating mode, wherein, when the AC power supply is normal, under overload conditions, the first power conversion module and the second power conversion module are configured to perform AC-DC conversion, and the third power conversion module is configured to perform DC-DC conversion, and the AC power supply and the DC power supply jointly power the DC bus.
[0012] According to the power converter of the present invention, preferably, when the AC power supply is abnormal, at least one of the first power conversion module and the second power conversion module is configured to perform DC-DC conversion; or, when the AC power supply is abnormal, at least one of the first power conversion module and the second power conversion module is configured to perform DC-DC conversion, and the third power conversion module is configured to perform DC-DC conversion.
[0013] According to the power converter of the present invention, preferably, during the switching period from DC-DC conversion to AC-DC conversion, the first power conversion module and the second power conversion module are configured, and the third power conversion module is configured to perform DC-DC conversion.
[0014] The power converter according to the present invention preferably further comprises a fourth switch module and a fourth power conversion module, wherein the fourth power conversion module comprises two bridge arms.
[0015] The fourth switch module is configured to selectively connect the input end of the fourth power conversion module to the third phase or neutral line of the AC power supply, and
[0016] The fourth power conversion module is configured to enable the two bridge arms to perform AC-DC conversion independently of each other, so that the DC bus is powered by the third phase of the AC power supply; or is configured to enable the two bridge arms to balance the DC bus independently of each other.
[0017] According to the power converter of the present invention, preferably, the first power conversion module, the second power conversion module or the fourth power conversion module includes a first bridge arm, a second bridge arm, a first inductor and a second inductor,
[0018] The first bridge arm includes a first transistor and a second transistor connected in series, and a node between the first transistor and the second transistor is electrically connected to the first end of the first inductor;
[0019] The second bridge arm is connected in parallel with the first bridge arm and includes a third transistor and a fourth transistor connected in series, and a node between the third transistor and the fourth transistor is electrically connected to the first end of the second inductor;
[0020] The second end of the first inductor and the second end of the second inductor are input ends of the first power conversion module, the second power conversion module or the fourth power conversion module;
[0021] A node between the first transistor and the third transistor is electrically connected to the positive electrode of the DC bus, and a node between the second transistor and the fourth transistor is electrically connected to the negative electrode of the DC bus.
[0022] According to the power converter of the present invention, preferably, the first transistor and the second transistor are configured to be alternately turned on or the third transistor and the fourth transistor are configured to be alternately turned on, thereby performing the AC-DC conversion.
[0023] According to the power converter of the present invention, preferably, the first transistor and the fourth transistor of the first power conversion module or the second power conversion module are configured to be turned on, and the second transistor and the third transistor of the first power conversion module or the second power conversion module are configured to be turned off, thereby performing the DC-DC conversion, or
[0024] The second transistor and the third transistor of the first power conversion module or the second power conversion module are configured to be turned on, and the first transistor and the fourth transistor of the first power conversion module or the second power conversion module are configured to be turned off, thereby performing the DC-DC conversion.
[0025] The present invention also provides an uninterruptible power supply, comprising the power converter according to the present invention.
[0026] Compared with the prior art, the power converter circuit of the present invention has a simple circuit topology, a small size, a low cost and a high circuit utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The embodiments of the present invention are further described below with reference to the accompanying drawings, in which:
[0028] Figure 1 A circuit topology of a power converter according to an embodiment of the present invention;
[0029] Figure 2-5 Show Figure 1 The current path of the power converter shown when performing AC-DC conversion;
[0030] Figure 6-7 Show Figure 1 The current path of the power converter shown when performing DC-DC conversion;
[0031] Figure 8 A circuit topology of a power converter according to another embodiment of the present invention;
[0032] Figure 9 A circuit topology of a power converter according to another embodiment of the present invention;
[0033] Figure 10 A circuit topology of a power converter according to yet another embodiment of the present invention;
[0034] Figure 11 A circuit topology of a three-phase power converter according to another embodiment of the present invention is shown in FIG.
[0035] Figure 12 is a structural block diagram of a UPS according to an embodiment of the present invention; and
[0036] Figure 13 A structural block diagram of a UPS according to another embodiment of the present invention is shown. DETAILED DESCRIPTION
[0037] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.
[0038] One embodiment of the present invention provides a power converter, the circuit topology of which is as follows: Figure 1 As shown, it is configured to be electrically connected to an AC power source AC (e.g., mains electricity) and a DC power source B (e.g., a rechargeable battery), and includes a power conversion module BR. Relays R1 and R2 control the conduction and disconnection between the AC power source AC and the power conversion module BR, and relays R1' and R2' control the conduction and disconnection between the DC power source B and the power conversion module BR.
[0039] Specifically, the power conversion module BR includes a first inductor L1, a second inductor L2, and a first bridge arm Lx and a second bridge arm Ly electrically connected to the first inductor L1 and the second inductor L2, respectively. The first bridge arm Lx includes a first N-type MOSFET transistor Q1 and a second N-type MOSFET transistor Q2 connected in series with each other, and a first diode D1 and a second diode D2 anti-parallel to the first transistor Q1 and the second transistor Q2, respectively. The node where the source of the first transistor Q1 and the drain of the second transistor Q2 are electrically connected is connected to the first end of the first inductor L1, and the second end of the first inductor L1 is configured to be able to pass through the relay R 1 is electrically connected to an AC power source AC or to the positive electrode of a DC power source via a relay R1'; a second bridge arm Ly includes a third N-type MOSFET transistor Q3 and a fourth N-type MOSFET transistor Q4 connected in series, and a third diode D3 and a fourth diode D4 connected in anti-parallel with the third transistor Q3 and the fourth transistor Q4, respectively. The node at which the source of the third transistor Q3 and the drain of the fourth transistor Q4 are electrically connected is connected to a first end of a second inductor L2, and the second end of the second inductor L2 is configured to be electrically connected to an AC power source AC via a relay R2 or to the negative electrode of a DC power source via a relay R2'. A node between the drain of the first transistor Q1 and the cathode of the first diode D1 is electrically connected to a node between the drain of the third transistor Q3 and the cathode of the third diode D3, and is electrically connected to a positive DC bus DC+. A node between the source of the second transistor Q2 and the anode of the second transistor D2 is electrically connected to a node between the source of the fourth transistor Q4 and the anode of the fourth diode D4, and is electrically connected to a negative DC bus DC-. The node between the positive DC bus capacitor Cp and the negative DC bus capacitor Cn is connected to the neutral line N (e.g., grounded or ungrounded). The output of the AC power supply AC is connected to the neutral line N via the filter capacitor C1. Those skilled in the art will appreciate that MOSFETs can conduct current in both directions, i.e., from source to drain or from drain to source. Furthermore, diodes connected in antiparallel to each transistor can be built into the MOSFET to achieve freewheeling between transistor switching intervals.
[0040] The working mode of the power converter of this embodiment is as follows:
[0041] In AC power mode (normal AC operation), relays R1 and R2 are closed, and relays R1' and R2' are open. At this point, the first inductor L1 and the first bridge arm Lx, or the second inductor L2 and the second bridge arm Ly, form an AC-DC converter. Pulse-width modulation (PWM) control signals are provided to the gates of transistors Q1-Q4 to turn the transistors on and off, achieving AC-DC conversion. The AC power supply then supplies power to the DC bus capacitors Cp and Cn. The PWM control signals can be provided by a dedicated controller. For example, the controller can include a processing circuit that controls the on / off drive of each MOSFET transistor. This processing circuit can be comprised of digital electronic circuits such as a processing device and a storage device, analog electronic circuits such as a comparator, an operational amplifier, or a differential amplifier, or a combination of both.
[0042] Specifically, see Figure 2-5 The current path when the mains is used to supply power to the DC bus capacitor is shown. For the sake of clarity, the battery and its related circuit connections in the circuit topology are omitted. In addition, since the first bridge arm Lx and the second bridge arm Ly are parallel power modules, their operating modes are the same. The first bridge arm Lx is used as an example for illustration. For the sake of clarity, the second bridge arm Ly and its related circuit connections are also omitted in the figure.
[0043] When the input AC power is in the positive half cycle, in the first time period, such as Figure 2 As shown, the second transistor Q2 of the first bridge arm Lx is turned on, and the first transistor Q1 is turned off. The current path is: AC→R1→L1→Q2→DC-→Cn→neutral line N. At this time, the inductor L1 stores energy; in the subsequent second time period, as shown Figure 3 As shown, the first transistor Q1 of the first bridge arm Lx is turned on, and the second transistor Q2 is turned off. The current path is: AC → R1 → L1 → Q1 → DC+ → Cp → neutral line N. At this time, the inductor L1 continues the current. In this way, by controlling the alternating conduction of the first transistor Q1 and the second transistor Q2, the positive DC bus capacitor Cp and the negative DC bus capacitor Cn can be charged.
[0044] When the input AC power is in the negative half cycle, in the first time period, such as Figure 4 As shown, the first transistor Q1 of the first bridge arm Lx is turned on and the second transistor Q2 is turned off. The current path is: neutral line N→Cp→DC+→Q1→L1→R1→AC. At this time, the inductor L1 stores energy. In the subsequent second time period, as shown Figure 5As shown, the second transistor Q2 of the first bridge arm Lx is turned on, and the first transistor Q1 is turned off. The current path is: neutral line N → Cn → DC- → Q2 → L1 → R1 → AC. At this time, the inductor L2 continues the current. In this way, by controlling the alternating conduction of the first transistor Q1 and the second transistor Q2, the positive DC bus capacitor Cp and the negative DC bus capacitor Cn can be charged.
[0045] Similarly, for the second bridge arm Ly, the third transistor Q3 and the fourth transistor Q4 are PWM controlled to be alternately turned on, so as to charge the DC bus capacitors Cp and Cn.
[0046] Preferably, in an embodiment of the present invention, the first bridge arm Lx and the second bridge arm Ly are independently controlled to realize AC-DC conversion, wherein the first bridge arm Lx and the second bridge arm Ly can be staggered in parallel or can perform AC-DC conversion simultaneously.
[0047] In battery mode (mains failure), relays R1 and R2 open, and relays R1' and R2' close. In this state, inductors L1-L2 and transistors Q1-Q4 form a DC-DC converter. Pulse-width modulation (PWM) control signals are provided to the gates of transistors Q1-Q4 to turn the transistors on and off, achieving DC-DC conversion. The DC power supply then supplies power to the DC bus capacitors Cp and Cn. The PWM control signals can be provided by a dedicated controller.
[0048] Specifically, see Figure 6-7 The two current paths shown in FIG. 1 are used when the battery charges the DC bus capacitors Cp and Cn. For clarity, the AC power supply and related circuit connections in the circuit topology are omitted.
[0049] First, the second transistor Q2 and the third transistor Q3 are controlled to be turned on, and the first transistor Q1 and the fourth transistor Q4 are turned off. The current path is:
[0050] B+→R1'→L1→Q2→DC-→Cn→Cp→DC+→Q3→L2→R2'→B-, such as Figure 6 As shown, at this time, inductors L1 and L2 store energy.
[0051] Then, the first transistor Q1 and the fourth transistor Q4 are controlled to be turned on, and the second transistor Q2 and the third transistor Q3 are turned off. The current path is:
[0052] B+→R1'→L1→Q1→DC+→Cp→Cn→DC-→Q4→L2→R2'→B-, such as Figure 7 As shown, at this time, the inductors L1 and L2 are freewheeling.
[0053] In this way, the charging of the DC bus capacitors Cp and Cn is realized, that is, DC-DC conversion is achieved.
[0054] The power converter of this embodiment can achieve both AC-DC conversion and DC-DC conversion, and has a simple circuit topology, low cost, small size, and high circuit utilization. In particular, when applied to a UPS, it can significantly reduce the size and cost of the UPS, thereby improving circuit utilization.
[0055] Another embodiment of the present invention provides a two-phase power converter, the circuit topology of which is as follows: Figure 8 As shown, it includes a first power conversion module BR1 and a second power conversion module BR2, both of which are rectifier modules. The specific circuit topology is similar to Figure 1 The power conversion modules BR shown have the same circuit topology. The first and second power conversion modules BR1 and BR2 correspond to the T-phase and S-phase of the AC power supply, respectively. Relays R11 and R12 control the connection and disconnection between the T-phase of the AC power supply AC and the first power conversion module BR1, while relays R11' and R12' control the connection and disconnection between the DC power supply B and the first power conversion module BR1. Relays R31 and R32 control the connection and disconnection between the S-phase of the AC power supply AC and the second power conversion module BR2, while relays R31' and R32' control the connection and disconnection between the DC power supply B and the second power conversion module BR2.
[0056] In this embodiment, the operating principles of the first and second power conversion modules BR1 and BR2 of the power converter are the same as those of the power conversion module BR in the aforementioned embodiment and are not further described herein. Specifically, when the mains power fails, the DC power supply can be DC-DC converted by at least one of the first and second power conversion modules BR1 and BR2. Using multiple power conversion modules for DC-DC conversion not only improves circuit utilization and reduces the load on the power conversion modules, but also increases the power density of the system and reduces costs.
[0057] Another embodiment of the present invention provides a power converter, the circuit topology of which is as follows: Figure 9 As shown, it is configured to be electrically connected to an AC power source AC (e.g., mains electricity) and a DC power source B (e.g., a rechargeable battery), and includes a first power conversion module (rectifier module) BR1 and a third power conversion module (DC-DC converter module) BR3. Relays R1 and R2 control the connection and disconnection between the AC power source AC and the rectifier module BR1, relays R1' and R2' control the connection and disconnection between the DC power source B and the rectifier module BR1, and relays R3 and R4 control the connection and disconnection between the DC power source B and the DC-DC converter module BR3.
[0058] Specifically, the circuit topology of the rectifier module BR1 is similar to Figure 1 The circuit topology of the power conversion module BR shown is the same and will not be described again here.
[0059] The DC-DC conversion module BR3 includes a DC-DC converter and inductors L3 and L4 electrically connected to the first and second ends of the DC-DC converter, respectively. The inductors L3 and L4 are also electrically connected to the positive and negative poles of the DC power supply through relays R3 and R4, respectively. The third and fourth ends of the DC-DC converter are electrically connected to the positive DC bus DC+ and DC-, respectively. Preferably, the DC-DC converter is a bidirectional DC-DC converter, that is, it can realize input from the first and second ends and output from the third and fourth ends; it can also realize input from the third and fourth ends and output from the first and second ends. In this embodiment, the DC-DC converter adopts a DC-DC conversion topology and control logic well known in the art, which will not be repeated here.
[0060] The working mode of the power converter of this embodiment is as follows:
[0061] In AC power mode (normal AC operation), relays R1 and R2 are closed, relays R1' and R2' are disconnected, and relays R3 and R4 are disconnected. At this point, transistors Q1-Q4 are controlled on and off similarly to the previous embodiment to achieve AC-DC conversion, with the AC power supply charging the DC bus capacitors Cp and Cn.
[0062] In battery charging mode, if rechargeable battery B is low on power, it needs to be charged. At this point, relays R1 and R2 are closed, relays R1' and R2' are disconnected, and relays R3 and R4 are closed. The DC bus charges rechargeable battery B through DC-DC converter module BR3.
[0063] In battery mode (mains power failure), relays R1 and R2 are disconnected, relays R1' and R2' are closed, and relays R3 and R4 are closed. At this time, the conduction and disconnection of transistors Q1-Q4 are controlled similarly to the previous embodiment to achieve DC-DC conversion, and DC power supply B supplies power to DC bus capacitors Cp and Cn. Preferably, DC-DC conversion module BR3 is simultaneously used to perform DC-DC conversion, and DC power supply B charges DC bus capacitors Cp and Cn. In this way, DC power supply B jointly supplies power to the DC bus through the first power conversion module BR1 and the third power conversion module BR3, greatly improving the power supply efficiency of the DC power supply, reducing the load power of the DC-DC conversion module BR3, and significantly reducing the cost and volume of the power converter. Furthermore, using DC-DC converter module BR3 to simultaneously perform DC-DC conversion also ensures power supply continuity during the switching process of transistors in rectifier module BR1. Specifically, when rectifier module BR1 switches from DC-DC conversion mode to rectification mode, DC-DC converter module BR3 carries the load power supply at the moment of switching. At this time, DC-DC converter module BR3 may have an overload of 150% to 200%, and the overload capacity of its transistors can be selected based on actual conditions. Furthermore, if only rectifier module BR1 performs DC-DC conversion, when switching from DC-DC conversion mode to rectification mode, DC-DC converter module BR3 can be turned on before switching, and then the function of rectifier module BR1 can be switched to ensure power supply continuity.
[0064] In particular, if the mains operates normally, under heavy load conditions, the DC bus can be powered by both the mains and the rechargeable battery B.
[0065] The power converter of this embodiment can achieve both AC-DC and DC-AC conversion, and has a simple circuit topology, low cost, small size, high circuit utilization, and strong load capacity. In particular, when applied to a UPS, it can significantly reduce the size and cost of the UPS, thereby improving circuit utilization.
[0066] Another embodiment of the present invention provides a power converter, the circuit topology of which is as follows: Figure 10As shown, it is configured to be electrically connected to an AC power source AC (e.g., mains electricity) and a DC power source B (e.g., a rechargeable battery), and includes a first power conversion module (rectifier module) BR1, a second power conversion module (rectifier module) BR2, and a third power conversion module (DC-DC conversion module) BR3. Relays R11 and R12 control the connection and disconnection between the T phase of the AC power source AC and the rectifier module BR1, relays R11' and R12' control the connection and disconnection between the DC power source B and the rectifier module BR1, relays R31 and R32 control the connection and disconnection between the S phase of the AC power source AC and the second power conversion module BR2, relays R31' and R32' control the connection and disconnection between the DC power source B and the second power conversion module BR2; relays R3 and R4 control the connection and disconnection between the DC power source B and the DC-DC conversion module BR3.
[0067] In this embodiment, the working principles of the first and second power conversion modules BR1 and BR2 of the power converter are the same as the working principles of the power conversion module BR in the aforementioned embodiment, and the working principle of the third power conversion module BR3 is the same as the working principle of the DC-DC conversion module in the aforementioned embodiment, which will not be repeated here. In particular, when the mains power fails, the DC power supply can be DC-DC converted by at least one of the first and second power conversion modules BR1 and BR2, or DC-DC converted by at least one of the first and second power conversion modules BR1 and BR2, while also being DC-DC converted by the third power conversion module BR3. Using multiple power conversion modules to perform DC-DC conversion can not only improve circuit utilization and reduce the load of the power conversion modules, but also improve the power density of the system and reduce costs. In addition, using the third power conversion module BR3 to perform DC-DC conversion can also ensure the continuity of power supply during the transistor switching process.
[0068] Another embodiment of the present invention provides a three-phase power converter, the circuit topology of which is as follows: Figure 11 As shown, it is Figure 10A fourth power conversion module BR4 is added to the circuit topology shown. BR4 is a rectifier module, and its circuit topology is identical to that of the first power conversion module BR1. The first, second, and fourth power conversion modules BR1, BR2, and BR4 correspond to the T, S, and R phases of the three-phase AC power supply, respectively. Relays R11 and R12 control the conduction and disconnection between the T phase of the AC power supply AC and the first power conversion module BR1, and relays R11' and R12' control the conduction and disconnection between the DC power supply B and the first power conversion module BR1; relays R3 and R4 control the conduction and disconnection between the DC power supply B and the DC-DC conversion module BR3; relays R31 and R32 control the conduction and disconnection between the S phase of the AC power supply AC and the second power conversion module BR2, and relays R31' and R32' control the conduction and disconnection between the DC power supply B and the second power conversion module BR2; relays R41 and R42 control the conduction and disconnection between the R phase of the AC power supply AC and the fourth power conversion module BR4, and relays R41' and R42' control the conduction and disconnection between the fourth power conversion module BR4 and the neutral line N.
[0069] In this embodiment, the first, second and fourth power conversion modules BR1, BR2 and BR4 of the power converter have the same working principle when performing AC-DC conversion, and are the same as the working principle of the mains mode in the above embodiment. The difference is that when the mains fails, the DC power supply can be converted to DC-DC by at least two of the first, second and fourth power conversion modules BR1, BR2 and BR4 and the third power conversion module BR3. Figure 11 As shown, power conversion modules BR1, BR2, and BR3 are used together to perform DC-DC conversion. Those skilled in the art will appreciate that power conversion modules BR1-BR4 can also be used together to perform DC-DC conversion. Using multiple power conversion modules for DC-DC conversion not only improves circuit utilization and reduces the load on the power conversion modules, but also increases system power density and reduces costs.
[0070] Generally, all loads cannot be completely balanced. In particular, for a three-phase power supply, if only a single-phase load is connected, the load will be very unbalanced. In this case, it is necessary to control the balance of the positive and negative DC buses. In battery mode, it is preferred to use the fourth power conversion module BR4 as a balancing branch and control its transistors to conduct alternately to achieve the balance of the DC bus. Specifically, Figure 11As shown, if the voltage of capacitor Cp is higher than the voltage of capacitor Cn, taking the first bridge arm of the fourth power conversion module BR4 as an example, the second bridge arm has a similar operating logic to the first bridge arm. When transistor Q41 is on, transistor Q42 is off, and relay R41' is closed and relay R41 is off, inductor L41 stores energy, and the current path is: DC+→Q41→L41→R41'→neutral line N→Cp; after inductor L41 completes energy storage, transistor Q41 is off, transistor Q42 is on, and inductor L41 continues to release energy, and the current path is: neutral line N→R41'→L41→Q42→DC-→Cn. That is, when the voltage of Bus+ (Cp) is higher than that of Bus- (Cn), capacitor Cp discharges the stored energy to inductor L41, and inductor L41 continues to release energy to capacitor Cn. Similarly, if the voltage of capacitor Cn is higher than the voltage of capacitor Cp, taking the second bridge arm of the fourth power conversion module BR4 as an example, the first bridge arm and the second bridge arm have similar operating logic. When transistor Q44 is turned on, transistor Q43 is turned off, and relay R42' is closed and relay R42 is turned off, inductor L42 stores energy, and the current path is: neutral line N → Cn → DC- → Q44 → L42 → R42'; when inductor L42 completes energy storage, transistor Q44 is turned off, transistor Q43 is turned on, and inductor L42 continues to release energy, and the current path is: neutral line N → R41' → L42 → Q43 → DC+ → Cp. That is, when the Bus+ (Cn) voltage is higher than the Bus- (Cp) voltage, capacitor Cn discharges the stored energy to inductor L42, and inductor L42 continues to release energy to capacitor Cp. In this way, the balance of the positive and negative DC bus is achieved.
[0071] One embodiment of the present invention provides a UPS, see Figure 12 The structural block diagram of the UPS of this embodiment shown includes a power converter 1001, an inverter 1002, a battery charging module 1003 and a rechargeable battery 1004. Compared with the traditional UPS, the power converter 1001 of the UPS of this embodiment can convert the output of the rechargeable battery 1004 into DC-DC and provide it to the DC bus, omitting the dedicated battery discharge module, reducing the size of the UPS and saving costs.
[0072] Another embodiment of the present invention provides another UPS, see Figure 13The block diagram of the UPS structure of this embodiment is shown, which includes a power converter 1101, an inverter 1102, a battery charging module 1103, a rechargeable battery 1104, and a battery discharge module 1105. Compared to traditional UPSs, this embodiment can simultaneously use the battery discharge module 1105 and the power converter 1101 to deliver power from the battery 1104 to the DC bus, improving battery power efficiency. Preferably, the battery charging module 1103 and the battery discharge module 1105 are replaced by a bidirectional DC-DC conversion module, reducing the size of the UPS and saving costs.
[0073] Because the power converter of the embodiment of the present invention can achieve different operating modes by controlling the switch, the UPS according to the embodiment of the present invention can directly convert the battery output to power the DC bus by the rectifier module or the battery conversion module when the load is low, and use both the rectifier module and the battery conversion module to convert the battery output to power the DC bus when the load is high. Therefore, the application scenarios of the UPS of the present invention are more extensive.
[0074] According to other embodiments of the present invention, the relays may be replaced with other switching elements, such as mechanical switches, circuit breakers, etc. In addition, the relay components (R11, R11'), (R12, R12'), (R31, R31'), (R32, R32'), (R41, R41'), and (R42, R42') may be replaced with single-pole double-throw switches.
[0075] According to other embodiments of the present invention, the N-type MOSFET transistor may be replaced by other transistors, such as a P-type MOSFET transistor, an IGBT transistor, etc.
[0076] Although the present invention has been described through preferred embodiments, the present invention is not limited to the embodiments described herein but includes various changes and modifications that may be made without departing from the scope of the present invention.
Claims
1. A power converter, comprising a first switching module and a second switching module and a first power conversion module and a second power conversion module, wherein each of the first power conversion module and the second power conversion module comprises two bridge arms. in, The first switch module is configured to selectively electrically connect the input end of the first power conversion module to the first phase of the AC power supply or the DC power supply. The second switch module is configured to selectively electrically connect the input end of the second power conversion module to the second phase of the AC power supply or the DC power supply, and The first power conversion module and the second power conversion module are configured so that the two bridge arms perform AC-DC conversion independently of each other, so that the DC bus is powered by the AC power supply; or are configured so that the two bridge arms perform DC-DC conversion in cooperation with each other, so that the DC bus is powered by the DC power supply.
2. The power converter according to claim 1, further comprising a third switch module and a third power conversion module, wherein: The third power conversion module is a DC-DC conversion module, the third switch module is configured to control the conduction and disconnection between the input end of the third power conversion module and the DC power supply, and the output end of the third power conversion module is electrically connected to the DC bus.
3. The power converter according to claim 2, comprising a heavy load operating mode, wherein: When the AC power supply is normal, under heavy load conditions, the first power conversion module and the second power conversion module are configured to perform AC-DC conversion, and the third power conversion module is configured to perform DC-DC conversion, and the AC power supply and the DC power supply jointly power the DC bus.
4. The power converter according to claim 2, wherein: When the AC power supply is abnormal, at least one of the first power conversion module and the second power conversion module is configured to perform DC-DC conversion; Alternatively, when the AC power supply is abnormal, at least one of the first power conversion module and the second power conversion module is configured to perform DC-DC conversion, and the third power conversion module is configured to perform DC-DC conversion.
5. The power converter according to claim 2, wherein: The first power conversion module and the second power conversion module are configured to switch from DC-DC conversion to AC-DC conversion, and the third power conversion module is configured to perform DC-DC conversion.
6. The power converter according to any one of claims 1 to 5, further comprising a fourth switch module and a fourth power conversion module, wherein the fourth power conversion module comprises two bridge arms. in, The fourth switch module is configured to selectively connect the input end of the fourth power conversion module to the third phase or neutral line of the AC power supply, and The fourth power conversion module is configured to enable the two bridge arms to perform AC-DC conversion independently of each other, so that the DC bus is powered by the third phase of the AC power supply; or is configured to enable the two bridge arms to balance the DC bus independently of each other.
7. The power converter according to claim 6, wherein: The first power conversion module, the second power conversion module or the fourth power conversion module includes a first bridge arm, a second bridge arm, a first inductor and a second inductor, The first bridge arm includes a first transistor and a second transistor connected in series, and a node between the first transistor and the second transistor is electrically connected to the first end of the first inductor; The second bridge arm is connected in parallel with the first bridge arm and includes a third transistor and a fourth transistor connected in series, and a node between the third transistor and the fourth transistor is electrically connected to the first end of the second inductor; The second end of the first inductor and the second end of the second inductor are input ends of the first power conversion module, the second power conversion module or the fourth power conversion module; A node between the first transistor and the third transistor is electrically connected to the positive electrode of the DC bus, and a node between the second transistor and the fourth transistor is electrically connected to the negative electrode of the DC bus.
8. The power converter according to claim 7, wherein: The first transistor and the second transistor are configured to be alternately turned on, or the third transistor and the fourth transistor are configured to be alternately turned on, thereby performing the AC-DC conversion.
9. The power converter according to claim 7, wherein: The first transistor and the fourth transistor of the first power conversion module or the second power conversion module are configured to be turned on, and the second transistor and the third transistor of the first power conversion module or the second power conversion module are configured to be turned off, thereby performing the DC-DC conversion, or The second transistor and the third transistor of the first power conversion module or the second power conversion module are configured to be turned on, and the first transistor and the fourth transistor of the first power conversion module or the second power conversion module are configured to be turned off, thereby performing the DC-DC conversion.
10. An uninterruptible power supply comprising the power converter according to any one of claims 1 to 9.