Single-phase uninterruptible power supply output voltage stabilization control method and system

Abstract

This invention provides a method and system for regulating the output voltage of a single-phase uninterruptible power supply (UPS). The UPS circuit mainly comprises three parts: a controllable rectifier module, a battery charging / discharging module, and an inverter voltage regulator module. The battery charging / discharging module needs to be able to switch between charging and discharging modes in a timely manner to achieve uninterrupted power supply to the load, which places high control requirements on the charging / discharging control system inside the UPS. A voltage closed-loop method is adopted, and the optimal control pulse is obtained based on the mathematical equations of the inverter voltage regulator module circuit, thereby reducing the output voltage fluctuation range.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of uninterruptible power supply control, and in particular to a single-phase uninterruptible power supply output voltage stabilization control method and system. Background Art

[0002] In order to improve the reliability of load power supply, some important loads are connected to the power grid through uninterruptible power supply. On the one hand, it can prevent the load from losing effective power supply when the power grid is cut off; on the other hand, the power supply quality on the load side can be further improved through the power conversion module related to the uninterruptible power supply, so as to achieve the effect of stabilizing the voltage amplitude and reduce the impact of power grid fluctuations on load performance. The uninterruptible power supply mainly consists of three parts: controllable rectifier module, battery charging and discharging module, and inverter voltage stabilization module. Among them, the controllable rectifier module converts the fluctuating AC grid voltage into a stable DC bus voltage, eliminating the impact of grid fluctuations. The inverter voltage stabilization module can convert DC power into stable AC power, achieving the effect of voltage stabilization on the load side.

[0003] Affected by the dead time of the switch tube and the line voltage drop, the output voltage of the inverter voltage regulator module will fluctuate. For example, an increase in line current will lead to an increase in line voltage drop, which will in turn lead to a low voltage on the load side. In addition, if the dead time of the switch tube is set too long, the actual output voltage amplitude will be low and different from the given value. Therefore, if the inverter voltage regulator module does not control the output voltage, the output voltage in the open-loop state will fluctuate to a certain extent, which is different from the theoretical given amplitude.

[0004] At present, the inverter voltage regulator modules in most uninterruptible power supplies adopt switch control mode, which cannot ensure the stability of output voltage. Some key equipment loads are sensitive to grid voltage fluctuations, and usually need to limit the fluctuation range to within ±3%. At this time, open-loop control mode cannot achieve high-precision voltage regulation requirements. Summary of the invention

[0005] The embodiment of the present invention provides a single-phase uninterruptible power supply output voltage stabilization control method and system, adopts a voltage closed-loop method, and obtains the optimal control pulse according to the mathematical equation of the inverter voltage stabilization module circuit, thereby reducing the output voltage fluctuation range.

[0006] In a first aspect, an embodiment of the present invention provides a method for controlling output voltage stabilization of a single-phase uninterruptible power supply, wherein the single-phase uninterruptible power supply comprises a controllable rectifier module, a battery charge and discharge module, and an inverter voltage stabilization module; the controllable rectifier module comprises a controllable rectifier full bridge and a filter capacitor, the two input ends of the controllable rectifier full bridge are respectively connected to the neutral line and the live line of the single-phase power supply, and the two output ends of the controllable rectifier full bridge are respectively connected to the two ends of the filter capacitor; the battery charge and discharge module and the inverter voltage stabilization module are connected to the two output ends of the controllable rectifier full bridge; the inverter voltage stabilization module comprises a third upper bridge arm switch tube and a third lower bridge arm switch tube; the emitter of the third upper bridge arm switch tube and the collector of the third lower bridge arm switch tube are connected to the power supply output end after being connected; the base of the third upper bridge arm switch tube and the third lower bridge arm switch tube are not connected; the method comprises:

[0007] Step S1, obtaining the DC bus voltage V dc , and output voltage V0 and output current I0, the DC bus voltage is the voltage across the filter capacitor;

[0008] Step S2: Based on the duty cycle D of the third upper bridge arm switch tube and the third lower bridge arm switch tube, the DC bus voltage V dc , output voltage V0 and output current I0 determine the voltage equation of the inverter voltage stabilization module;

[0009] Step S3, perform first-order Euler discretization on the voltage equation of the inverter voltage stabilization module to determine the output voltage V0(k) and duty cycle D at time k, the output current I0(k) at time k, and the DC bus voltage V at time k. dc The relationship between the output current I0(k-1) at time (k) and time k-1;

[0010] Step S4: set the output voltage to a given value Equal to the output voltage V0(k) at time k, to determine the optimal duty cycle, given by the voltage effective value The output voltage V0(k) is used as input, and the output voltage V0(k) is used as feedback value to input into the PID controller for closed-loop calculation to update the output voltage given value and determine the optimal duty cycle, and output a control pulse signal according to the optimal duty cycle.

[0011] Preferably, the battery charging and discharging module comprises a battery, a second upper bridge arm switch tube and a second lower bridge arm switch tube; the emitter of the second upper bridge arm switch tube and the collector of the second lower bridge arm switch tube are connected to one electrode of the battery; the base of the second upper bridge arm switch tube and the base of the second lower bridge arm switch tube are not connected;

[0012] One end of the filter capacitor, the base of the first upper bridge arm switch tube, the base of the second upper bridge arm switch tube and the base of the third upper bridge arm switch tube are connected; the emitter of the first lower bridge arm switch tube, the other end of the filter capacitor, the emitter of the second lower bridge arm switch tube, the other end of the battery and the emitter of the third lower bridge arm switch tube are connected;

[0013] The controllable rectifier module further includes a first resistor and a first inductor connected in series, one end of the first resistor is connected to the power input end, the other end of the first resistor is connected to the first inductor, and the first inductor, the emitter of the first upper bridge arm switch tube, and the collector of the first lower bridge arm switch tube are connected;

[0014] The battery charging and discharging module further includes a second inductor, one end of which is connected to one electrode of the battery, and the other end of which is connected to the emitter of the second upper bridge arm switch tube and the collector of the second lower bridge arm switch tube;

[0015] The inverter voltage stabilization module also includes a third inductor and a grounding capacitor, one end of the third inductor is connected to the emitter of the third upper bridge arm switch tube and the collector of the third lower bridge arm switch tube, and the other end of the third inductor is connected to the power output end, and the power output end is grounded through the grounding capacitor.

[0016] Preferably, in step S2, the voltage equation is:

[0017]

[0018]

[0019] In the above formula, L3 is the inductance of the third inductor, D is in the range of 0 to 1, and T on The duration of the third upper bridge arm switch tube being turned on and the third lower bridge arm switch tube being turned off, T off The duration of the third upper bridge arm switch tube being turned off and the third lower bridge arm switch tube being turned on.

[0020] As a preferred embodiment, in step S3, the output voltage V0(k) at time k and the duty cycle D, the output current I0(k) at time k, and the DC bus voltage V at time k are dc The relationship between the output current I0(k-1) at time (k) and time k-1 is:

[0021]

[0022] In the above formula, T s is the sampling period, T s =T on +T off .

[0023] Preferably, in step S4, the optimal duty cycle is:

[0024]

[0025] In a second aspect, an embodiment of the present invention provides a single-phase uninterruptible power supply circuit output voltage stabilization control system, wherein the single-phase uninterruptible power supply includes a controllable rectifier module, a battery charging and discharging module, and an inverter voltage stabilization module; the controllable rectifier module includes a controllable rectifier full bridge and a filter capacitor, the two input ends of the controllable rectifier full bridge are respectively connected to the neutral line and the live line of the single-phase power supply, and the two output ends of the controllable rectifier full bridge are respectively connected to the two ends of the filter capacitor; the battery charging and discharging module and the inverter voltage stabilization module are connected to the two output ends of the controllable rectifier full bridge; the inverter voltage stabilization module includes a third upper bridge arm switch tube and a third lower bridge arm switch tube; the emitter of the third upper bridge arm switch tube and the collector of the third lower bridge arm switch tube are connected to the power supply output end; the base of the third upper bridge arm switch tube and the third lower bridge arm switch tube are not connected; the system includes:

[0026] Acquisition unit, obtains DC bus voltage V dc , and output voltage V0 and output current I0, the DC bus voltage is the voltage across the filter capacitor;

[0027] The voltage calculation unit is based on the duty cycle D of the third upper bridge arm switch tube and the third lower bridge arm switch tube, and the DC bus voltage V dc , output voltage V0 and output current I0 determine the voltage equation of the inverter voltage stabilization module;

[0028] The duty cycle calculation unit performs first-order Euler discretization on the voltage equation of the inverter voltage stabilization module to determine the output voltage V0(k) and the duty cycle D at time k, the output current I0(k) at time k, and the DC bus voltage V at time k. dc The relationship between the output current I0(k-1) at time (k) and time k-1;

[0029] Closed-loop control unit, set the output voltage to a given value Equal to the output voltage V0(k) at time k, to determine the optimal duty cycle, given by the voltage effective value The output voltage V0(k) is used as input, and the output voltage V0(k) is used as feedback value to input into the PID controller for closed-loop calculation to update the output voltage given value and determine the optimal duty cycle, and output a control pulse signal according to the optimal duty cycle.

[0030] Preferably, the battery charging and discharging module comprises a battery, a second upper bridge arm switch tube and a second lower bridge arm switch tube; the emitter of the second upper bridge arm switch tube and the collector of the second lower bridge arm switch tube are connected to one electrode of the battery; the base of the second upper bridge arm switch tube and the base of the second lower bridge arm switch tube are not connected;

[0031] One end of the filter capacitor, the base of the first upper bridge arm switch tube, the base of the second upper bridge arm switch tube and the base of the third upper bridge arm switch tube are connected; the emitter of the first lower bridge arm switch tube, the other end of the filter capacitor, the emitter of the second lower bridge arm switch tube, the other end of the battery and the emitter of the third lower bridge arm switch tube are connected;

[0032] The controllable rectifier module further includes a first resistor and a first inductor connected in series, one end of the first resistor is connected to the power input end, the other end of the first resistor is connected to the first inductor, and the first inductor, the emitter of the first upper bridge arm switch tube, and the collector of the first lower bridge arm switch tube are connected;

[0033] The battery charging and discharging module further includes a second inductor, one end of which is connected to one electrode of the battery, and the other end of which is connected to the emitter of the second upper bridge arm switch tube and the collector of the second lower bridge arm switch tube;

[0034] The inverter voltage stabilization module also includes a third inductor and a grounding capacitor, one end of the third inductor is connected to the emitter of the third upper bridge arm switch tube and the collector of the third lower bridge arm switch tube, and the other end of the third inductor is connected to the power output end, and the power output end is grounded through the grounding capacitor.

[0035] Preferably, the voltage equation is:

[0036]

[0037]

[0038] In the above formula, L3 is the inductance of the third inductor, D is in the range of 0 to 1, and T on The duration of the third upper bridge arm switch tube being turned on and the third lower bridge arm switch tube being turned off, T off The duration of the third upper bridge arm switch tube being turned off and the third lower bridge arm switch tube being turned on.

[0039] As a preferred embodiment, the output voltage V0(k) at time k and the duty cycle D, the output current I0(k) at time k, and the DC bus voltage V at time k are dc The relationship between the output current I0(k-1) at time (k) and time k-1 is:

[0040]

[0041] In the above formula, T s is the sampling period, T s =T on +T off .

[0042] Preferably, the optimal duty cycle is:

[0043]

[0044] The embodiment of the present invention provides a single-phase uninterruptible power supply output voltage stabilization control method and system, and the uninterruptible power supply circuit mainly includes: a controllable rectifier module, a battery charging and discharging module, and an inverter voltage stabilization module. The battery charging and discharging module needs to be able to switch between charging mode and discharging mode in time to achieve uninterruptible power supply to the load, which puts forward higher control requirements for the charging and discharging control system inside the uninterruptible power supply. A voltage closed-loop method is adopted, and the optimal control pulse is obtained according to the mathematical equation of the inverter voltage stabilization module circuit, thereby reducing the output voltage fluctuation range. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 It is a flowchart of a method for controlling output voltage stabilization of a single-phase uninterruptible power supply according to an embodiment of the present invention;

[0047] Figure 2 A topological structure diagram of an uninterruptible power supply circuit according to an embodiment of the present invention;

[0048] Figure 3 A circuit topology diagram of an uninterruptible power supply inverter voltage stabilization module according to an embodiment of the present invention;

[0049] Figure 4 4 is a control block diagram of a charge and discharge current set value according to an embodiment of the present invention. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] In the embodiments of the present application, the term "and / or" is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B may represent three situations: A exists alone, A and B exist at the same time, and B exists alone.

[0052] The terms "first" and "second" in the embodiments of the present application are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first" and "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a system, product or device comprising a series of parts or units is not limited to the listed parts or units, but optionally also includes parts or units that are not listed, or optionally also includes other parts or units inherent to these products or devices. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0053] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0054] At present, the inverter voltage regulator modules in most uninterruptible power supplies adopt switch control mode, which cannot ensure the stability of output voltage. Some key equipment loads are sensitive to grid voltage fluctuations, and usually need to limit the fluctuation range to within ±3%. At this time, open-loop control mode cannot achieve high-precision voltage regulation requirements.

[0055] Therefore, the embodiment of the present invention provides a single-phase uninterruptible power supply output voltage stabilization control method and system, which adopts a closed-loop control method combined with an inverter voltage stabilization module circuit mathematical model to obtain the optimal control pulse, thereby reducing the output voltage fluctuation range. The following will be explained and introduced through multiple embodiments.

[0056] Figure 1 A single-phase uninterruptible power supply output voltage stabilization control method is provided in an embodiment of the present invention, wherein, Figure 2 As shown in , the single-phase uninterruptible power supply circuit includes a controllable rectifier module, a battery charging and discharging module and an inverter voltage stabilizing module;

[0057] The controllable rectifier module includes a controllable rectifier full bridge and a filter capacitor. The two input ends of the controllable rectifier full bridge are respectively connected to the neutral line and the live line of the single-phase power supply, and the two output ends of the controllable rectifier full bridge are respectively connected to the two ends of the filter capacitor; the battery charging and discharging module and the inverter voltage stabilizing module are connected to the two output ends of the controllable rectifier full bridge; the unidirectional power supply input terminal V in , the power input terminal is connected to the rectifier circuit, the controllable rectifier full bridge includes a first upper bridge arm switch tube Q1-1 and a first lower bridge arm switch tube Q1-2, the emitter of the first upper bridge arm switch tube Q1-1 and the collector of the first lower bridge arm switch tube Q1-2 are connected to the power input terminal V in The bases of the first upper bridge arm switch tube Q1-1 and the first lower bridge arm switch tube Q1-2 are not connected; the controllable rectifier module also includes a first resistor R1 and a first inductor L1 connected in series, and one end of the first resistor R1 is connected to the power input terminal V in The other end of the first resistor R1 is connected to the first inductor L1, and the first inductor L1, the emitter of the first upper bridge arm switch tube Q1-1, and the collector of the first lower bridge arm switch tube Q1-2 are connected.

[0058] The battery charge and discharge module includes a battery (i.e., the battery box in the figure), a second upper bridge arm switch tube Q2-1 and a second lower bridge arm switch tube Q2-2; the emitter of the second upper bridge arm switch tube Q2-1 and the collector of the second lower bridge arm switch tube Q2-2 are connected to one pole of the battery; the bases of the second upper bridge arm switch tube Q2-1 and the second lower bridge arm switch tube Q2-2 are not connected; the battery charge and discharge module also includes a second inductor L2, one end of the second inductor L2 is connected to one pole of the battery, and the other end of the second inductor L2 is connected to the emitter of the second upper bridge arm switch tube Q2-1 and the collector of the second lower bridge arm switch tube Q2-2.

[0059] The inverter voltage stabilization module includes a third upper bridge arm switch tube Q3-1 and a third lower bridge arm switch tube Q3-2; the emitter of the third upper bridge arm switch tube Q3-1 and the collector of the third lower bridge arm switch tube Q3-2 are connected to the power output terminal Vo; the bases of the third upper bridge arm switch tube Q3-1 and the third lower bridge arm switch tube Q3-2 are not connected; the inverter voltage stabilization module also includes a third inductor L3 and a grounding capacitor C1, one end of the third inductor L3 is connected to the emitter of the third upper bridge arm switch tube Q3-1 and the collector of the third lower bridge arm switch tube Q3-2, and the other end of the third inductor L3 is connected to the power output terminal Vo, and the power output terminal Vo is grounded through the grounding capacitor C1.

[0060] It also includes a filter capacitor, which includes multiple capacitors connected in series, one end of the filter capacitor, the base of the first upper bridge arm switch tube Q2-1, the base of the second upper bridge arm switch tube Q2-1 and the base of the third upper bridge arm switch tube Q3-1 are connected; the emitter of the first lower bridge arm switch tube Q1-2, the other end of the filter capacitor, the emitter of the second lower bridge arm switch tube Q2-2, the other pole of the battery, and the emitter of the third lower bridge arm switch tube Q3-2 are connected.

[0061] The battery charge and discharge module needs to be able to switch between the charge mode and the discharge mode in time to achieve uninterrupted power supply to the load, which places high control requirements on the charge and discharge control system inside the uninterruptible power supply. Batteries usually store electrical energy in the form of direct current, while the load usually adopts alternating current power supply. Therefore, in order to ensure reliable power supply in emergency situations, the battery charge and discharge module and the inverter voltage stabilization module need to cooperate with each other to timely convert the direct current stored in the battery into an alternating current output that meets the demand.

[0062] In this embodiment, Figure 2 As shown. To achieve uninterrupted and reliable power supply to the load, the controllable rectifier module is responsible for providing a stable DC bus voltage and eliminating unnecessary reactive power; the battery charging and discharging module is responsible for charging the battery to store electric energy when the power grid is powered, and when the power grid suddenly loses power, the battery provides emergency and reliable power supply; the inverter and voltage stabilizing module converts the DC bus voltage into an AC voltage with an amplitude and frequency that meet the requirements. The embodiment of the present invention mainly optimizes the control method of the uninterruptible power supply inverter and voltage stabilizing module, stabilizes the output voltage amplitude, and the circuit topology is as follows Figure 3 As shown. The main process of the single-phase uninterruptible power supply output voltage stabilization control method is as follows:

[0063] Step S1, obtaining the DC bus voltage V dc , and output voltage V0 and output current I0, the DC bus voltage is the voltage across the filter capacitor; obtain the sampling values ​​V0(k), I0(k), V dc(k).

[0064] Step S2: Based on the duty cycle D of the third upper bridge arm switch tube and the third lower bridge arm switch tube, the DC bus voltage V dc , output voltage V0 and output current I0 determine the voltage equation of the inverter voltage stabilization module;

[0065] Figure 2 This is the circuit topology of the inverter voltage regulator module. According to this circuit topology, the voltage equation is written as:

[0066]

[0067]

[0068] In the above formula, L3 is the inductance of the third inductor, D is in the range of 0 to 1, and T on The duration of the third upper bridge arm switch tube being turned on and the third lower bridge arm switch tube being turned off, T off The duration of the third upper bridge arm switch tube being turned off and the third lower bridge arm switch tube being turned on.

[0069] Step S3, perform first-order Euler discretization on the voltage equation of the inverter voltage stabilization module to determine the output voltage V0(k) and duty cycle D at time k, the output current I0(k) at time k, and the DC bus voltage V at time k. dc The relationship between the output current I0(k-1) at time (k) and time k-1;

[0070] According to formula (1), the first-order Euler discretization method is adopted, and the discretization formula is as follows:

[0071]

[0072] In the above formula, T s is the sampling period, T s =T on +T off .

[0073] Step S4: set the output voltage to a given value Equal to the output voltage V0(k) at time k, to determine the optimal duty cycle, given by the voltage effective value The output voltage V0(k) is used as input, and the output voltage V0(k) is used as feedback value to input into the PID controller for closed-loop calculation to update the output voltage given value and determine the optimal duty cycle, and output a control pulse signal according to the optimal duty cycle.

[0074] Assume that the output voltage is given by Let the output voltage value at time k be equal to the given value, that is:

[0075]

[0076] Combining equations (2) and (3), the optimal duty cycle expression can be derived as:

[0077]

[0078] In addition, in order to further reduce voltage fluctuations, a voltage closed loop is used to further correct the output voltage given value, such as Figure 4 As shown. Using the voltage closed loop method, when the actual output voltage RMS value is lower than the voltage given RMS value Ability to increase output voltage setpoint Then the actual output voltage value will be increased; conversely, the output voltage set value can be reduced The actual output voltage value is reduced. Therefore, the voltage closed loop method can sense the change of the output voltage and adjust it, thereby reducing the voltage fluctuation. The control pulse signal is output according to the optimal duty cycle value.

[0079] In a second aspect, an embodiment of the present invention provides a single-phase uninterruptible power supply circuit output voltage stabilization control system, wherein, Figure 2 As shown in , the single-phase uninterruptible power supply circuit includes a controllable rectifier module, a battery charging and discharging module and an inverter voltage stabilizing module;

[0080] The controllable rectifier module includes a controllable rectifier full bridge and a filter capacitor. The two input ends of the controllable rectifier full bridge are respectively connected to the neutral line and the live line of the single-phase power supply, and the two output ends of the controllable rectifier full bridge are respectively connected to the two ends of the filter capacitor; the battery charging and discharging module and the inverter voltage stabilizing module are connected to the two output ends of the controllable rectifier full bridge; the unidirectional power supply input terminal V in , the power input terminal is connected to the rectifier circuit, the controllable rectifier full bridge includes a first upper bridge arm switch tube Q1-1 and a first lower bridge arm switch tube Q1-2, the emitter of the first upper bridge arm switch tube Q1-1 and the collector of the first lower bridge arm switch tube Q1-2 are connected to the power input terminal V in The bases of the first upper bridge arm switch tube Q1-1 and the first lower bridge arm switch tube Q1-2 are not connected; the controllable rectifier module also includes a first resistor R1 and a first inductor L1 connected in series, and one end of the first resistor R1 is connected to the power input terminal V in The other end of the first resistor R1 is connected to the first inductor L1, and the first inductor L1, the emitter of the first upper bridge arm switch tube Q1-1, and the collector of the first lower bridge arm switch tube Q1-2 are connected.

[0081] The battery charge and discharge module includes a battery (i.e., the battery box in the figure), a second upper bridge arm switch tube Q2-1 and a second lower bridge arm switch tube Q2-2; the emitter of the second upper bridge arm switch tube Q2-1 and the collector of the second lower bridge arm switch tube Q2-2 are connected to one pole of the battery; the bases of the second upper bridge arm switch tube Q2-1 and the second lower bridge arm switch tube Q2-2 are not connected; the battery charge and discharge module also includes a second inductor L2, one end of the second inductor L2 is connected to one pole of the battery, and the other end of the second inductor L2 is connected to the emitter of the second upper bridge arm switch tube Q2-1 and the collector of the second lower bridge arm switch tube Q2-2.

[0082] The inverter voltage stabilization module includes a third upper bridge arm switch tube Q3-1 and a third lower bridge arm switch tube Q3-2; the emitter of the third upper bridge arm switch tube Q3-1 and the collector of the third lower bridge arm switch tube Q3-2 are connected to the power output terminal Vo; the bases of the third upper bridge arm switch tube Q3-1 and the third lower bridge arm switch tube Q3-2 are not connected; the inverter voltage stabilization module also includes a third inductor L3 and a grounding capacitor C1, one end of the third inductor L3 is connected to the emitter of the third upper bridge arm switch tube Q3-1 and the collector of the third lower bridge arm switch tube Q3-2, and the other end of the third inductor L3 is connected to the power output terminal Vo, and the power output terminal Vo is grounded through the grounding capacitor C1.

[0083] It also includes a filter capacitor, which includes multiple capacitors connected in series, one end of the filter capacitor, the base of the first upper bridge arm switch tube Q2-1, the base of the second upper bridge arm switch tube Q2-1 and the base of the third upper bridge arm switch tube Q3-1 are connected; the emitter of the first lower bridge arm switch tube Q1-2, the other end of the filter capacitor, the emitter of the second lower bridge arm switch tube Q2-2, the other pole of the battery, and the emitter of the third lower bridge arm switch tube Q3-2 are connected.

[0084] The battery charge and discharge module needs to be able to switch between the charge mode and the discharge mode in time to achieve uninterrupted power supply to the load, which places high control requirements on the charge and discharge control system inside the uninterruptible power supply. Batteries usually store electrical energy in the form of direct current, while the load usually adopts alternating current power supply. Therefore, in order to ensure reliable power supply in emergency situations, the battery charge and discharge module and the inverter voltage stabilization module need to cooperate with each other to timely convert the direct current stored in the battery into an alternating current output that meets the demand.

[0085] In this embodiment, Figure 2As shown. To achieve uninterrupted and reliable power supply to the load, the controllable rectifier module is responsible for providing a stable DC bus voltage and eliminating unnecessary reactive power; the battery charging and discharging module is responsible for charging the battery to store electric energy when the power grid is powered, and when the power grid suddenly loses power, the battery provides emergency and reliable power supply; the inverter and voltage stabilizing module converts the DC bus voltage into an AC voltage with an amplitude and frequency that meet the requirements. The embodiment of the present invention mainly optimizes the control method of the uninterruptible power supply inverter and voltage stabilizing module, stabilizes the output voltage amplitude, and the circuit topology is as follows Figure 3 As shown. The single-phase uninterruptible power supply output voltage stabilization control system includes:

[0086] Acquisition unit, obtains DC bus voltage V dc , and output voltage V0 and output current I0, the DC bus voltage is the voltage across the filter capacitor; obtain the sampling values ​​V0(k), I0(k), V dc (k).

[0087] The voltage calculation unit is based on the duty cycle D of the third upper bridge arm switch tube and the third lower bridge arm switch tube, and the DC bus voltage V dc , output voltage V0 and output current I0 determine the voltage equation of the inverter voltage stabilization module;

[0088] Figure 2 This is the circuit topology of the inverter voltage regulator module. According to this circuit topology, the voltage equation is written as:

[0089]

[0090]

[0091] In the above formula, L3 is the inductance of the third inductor, D is in the range of 0 to 1, and T on The duration of the third upper bridge arm switch tube being turned on and the third lower bridge arm switch tube being turned off, T off The duration of the third upper bridge arm switch tube being turned off and the third lower bridge arm switch tube being turned on.

[0092] The duty cycle calculation unit performs first-order Euler discretization on the voltage equation of the inverter voltage stabilization module to determine the output voltage V0(k) and the duty cycle D at time k, the output current I0(k) at time k, and the DC bus voltage V at time k. dc The relationship between the output current I0(k-1) at time (k) and time k-1;

[0093] According to formula (1), the first-order Euler discretization method is adopted, and the discretization formula is as follows:

[0094]

[0095] In the above formula, T sis the sampling period, T s =T on +T off .

[0096] Closed-loop control unit, set the output voltage to a given value Equal to the output voltage V0(k) at time k, to determine the optimal duty cycle, given by the voltage effective value The output voltage V0(k) is used as input, and the output voltage V0(k) is used as feedback value to input into the PID controller for closed-loop calculation to update the output voltage given value and determine the optimal duty cycle, and output a control pulse signal according to the optimal duty cycle.

[0097] Assume that the output voltage is given by Let the output voltage value at time k be equal to the given value, that is:

[0098]

[0099] Combining equations (2) and (3), the optimal duty cycle expression can be derived as:

[0100]

[0101] In addition, in order to further reduce voltage fluctuations, a voltage closed loop is used to further correct the output voltage given value, such as Figure 4 As shown. Using the voltage closed loop method, when the actual output voltage RMS value is lower than the voltage given RMS value Ability to increase output voltage setpoint Then the actual output voltage value will be increased; conversely, the output voltage set value can be reduced The actual output voltage value is reduced. Therefore, the voltage closed loop method can sense the change of the output voltage and adjust it, thereby reducing the voltage fluctuation. The control pulse signal is output according to the optimal duty cycle value.

[0102] The various embodiments of the present invention can be combined arbitrarily to achieve different technical effects.

[0103] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented by software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in this application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website site, computer, server or data center to another website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) mode. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state hard disk SolidStateDisk), etc.

[0104] Those skilled in the art can understand that to implement all or part of the processes in the above-mentioned embodiments, the processes can be completed by computer programs to instruct related hardware, and the programs can be stored in computer-readable storage media. When the programs are executed, they can include the processes of the above-mentioned method embodiments. The aforementioned storage media include: ROM or random access memory RAM, magnetic disk or optical disk and other media that can store program codes.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention 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 make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling output voltage stabilization of a single-phase uninterruptible power supply circuit, the single-phase uninterruptible power supply comprising a controllable rectifier module, a battery charge and discharge module and an inverter voltage stabilization module; the controllable rectifier module comprises a controllable rectifier full bridge and a filter capacitor, the two input ends of the controllable rectifier full bridge are respectively connected to the neutral line and the live line of the single-phase power supply, and the two output ends of the controllable rectifier full bridge are respectively connected to the two ends of the filter capacitor; the battery charge and discharge module and the inverter voltage stabilization module are connected to the two output ends of the controllable rectifier full bridge; the inverter voltage stabilization module comprises a third upper bridge arm switch tube and a third lower bridge arm switch tube; the emitter of the third upper bridge arm switch tube and the collector of the third lower bridge arm switch tube are connected to the power supply output end; the bases of the third upper bridge arm switch tube and the third lower bridge arm switch tube are not connected; it is characterized in that The method comprises: Step S1, obtaining the DC bus voltage V dc , and output voltage V0 and output current I0, the DC bus voltage is the voltage across the filter capacitor; Step S2: Based on the duty cycle D of the third upper bridge arm switch tube and the third lower bridge arm switch tube, the DC bus voltage V dc , output voltage V0 and output current I0 determine the voltage equation of the inverter voltage stabilization module; Step S3, perform first-order Euler discretization on the voltage equation of the inverter voltage stabilization module to determine the output voltage V0(k) and duty cycle D at time k, the output current I0(k) at time k, and the DC bus voltage V at time k. dc The relationship between the output current I0(k-1) at time (k) and time k-1; Step S4: Set the output voltage to a given value V o * = equal to the output voltage V0(k) at time k to determine the optimal duty cycle, given by the voltage effective value V o ref The output voltage V0(k) is used as input, and the output voltage V0(k) is used as feedback value to input into the PID controller for closed-loop calculation to update the output voltage given value and determine the optimal duty cycle, and output a control pulse signal according to the optimal duty cycle.

2. The single-phase uninterruptible power supply circuit output voltage stabilization control method according to claim 1, characterized in that: The controllable rectifier full bridge includes a first upper bridge arm switch tube and a first lower bridge arm switch tube, the emitter of the first upper bridge arm switch tube and the collector of the first lower bridge arm switch tube are connected to the power input end; the base of the first upper bridge arm switch tube and the first lower bridge arm switch tube are not connected; the battery charging and discharging module includes a battery, a second upper bridge arm switch tube and a second lower bridge arm switch tube; the emitter of the second upper bridge arm switch tube and the collector of the second lower bridge arm switch tube are connected to one electrode of the battery; the base of the second upper bridge arm switch tube and the second lower bridge arm switch tube are not connected; One end of the filter capacitor, the base of the first upper bridge arm switch tube, the base of the second upper bridge arm switch tube and the base of the third upper bridge arm switch tube are connected; the emitter of the first lower bridge arm switch tube, the other end of the filter capacitor, the emitter of the second lower bridge arm switch tube, the other end of the battery and the emitter of the third lower bridge arm switch tube are connected; The controllable rectifier module further includes a first resistor and a first inductor connected in series, one end of the first resistor is connected to the power input end, the other end of the first resistor is connected to the first inductor, and the first inductor, the emitter of the first upper bridge arm switch tube, and the collector of the first lower bridge arm switch tube are connected; The battery charging and discharging module further includes a second inductor, one end of which is connected to one electrode of the battery, and the other end of which is connected to the emitter of the second upper bridge arm switch tube and the collector of the second lower bridge arm switch tube; The inverter voltage stabilization module also includes a third inductor and a grounding capacitor, one end of the third inductor is connected to the emitter of the third upper bridge arm switch tube and the collector of the third lower bridge arm switch tube, and the other end of the third inductor is connected to the power output end, and the power output end is grounded through the grounding capacitor.

3. The output voltage stabilization control method of a single-phase uninterruptible power supply circuit according to claim 2, characterized in that: In step S2, the voltage equation is: In the above formula, L3 is the inductance of the third inductor, D is in the range of 0 to 1, and T on The duration of the third upper bridge arm switch tube being turned on and the third lower bridge arm switch tube being turned off, T off The duration of the third upper bridge arm switch tube being turned off and the third lower bridge arm switch tube being turned on.

4. The output voltage stabilization control method of a single-phase uninterruptible power supply circuit according to claim 3, characterized in that: In step S3, the output voltage V0(k) at time k and the duty cycle D, the output current I0(k) at time k, and the DC bus voltage V at time k are dc The relationship between the output current I0(k-1) at time (k) and time k-1 is: In the above formula, T s is the sampling period, T s =T on +T off .

5. The output voltage stabilization control method of a single-phase uninterruptible power supply circuit according to claim 4, characterized in that: In step S4, the optimal duty cycle is:

6. A single-phase uninterruptible power supply circuit output voltage stabilization control system, characterized in that: The single-phase uninterruptible power supply includes a controllable rectifier module, a battery charging and discharging module and an inverter voltage stabilizing module; the controllable rectifier module includes a controllable rectifier full bridge and a filter capacitor, the two input ends of the controllable rectifier full bridge are respectively connected to the neutral line and the live line of the single-phase power supply, and the two output ends of the controllable rectifier full bridge are respectively connected to the two ends of the filter capacitor; the battery charging and discharging module and the inverter voltage stabilizing module are connected to the two output ends of the controllable rectifier full bridge; the inverter voltage stabilizing module includes a third upper bridge arm switch tube and a third lower bridge arm switch tube; the emitter of the third upper bridge arm switch tube and the collector of the third lower bridge arm switch tube are connected to the power supply output end; the base of the third upper bridge arm switch tube and the third lower bridge arm switch tube are not connected; the system includes: Acquisition unit, obtains DC bus voltage V dc , and output voltage V0 and output current I0, the DC bus voltage is the voltage across the filter capacitor; The voltage calculation unit is based on the duty cycle D of the third upper bridge arm switch tube and the third lower bridge arm switch tube, and the DC bus voltage V dc , output voltage V0 and output current I0 determine the voltage equation of the inverter voltage stabilization module; The duty cycle calculation unit performs first-order Euler discretization on the voltage equation of the inverter voltage stabilization module to determine the output voltage V0(k) and the duty cycle D at time k, the output current I0(k) at time k, and the DC bus voltage V at time k. dc The relationship between the output current I0(k-1) at time (k) and time k-1; Closed-loop control unit, set the output voltage to a given value Equal to the output voltage V0(k) at time k, to determine the optimal duty cycle, given by the voltage effective value The output voltage V0(k) is used as input, and the output voltage V0(k) is used as feedback value to input into the PID controller for closed-loop calculation to update the output voltage given value and determine the optimal duty cycle, and output a control pulse signal according to the optimal duty cycle.

7. The single-phase uninterruptible power supply circuit output voltage stabilization control system according to claim 6, characterized in that: The controllable rectifier full bridge includes a first upper bridge arm switch tube and a first lower bridge arm switch tube, the emitter of the first upper bridge arm switch tube and the collector of the first lower bridge arm switch tube are connected to the power input end; the base of the first upper bridge arm switch tube and the first lower bridge arm switch tube are not connected; the battery charging and discharging module includes a battery, a second upper bridge arm switch tube and a second lower bridge arm switch tube; the emitter of the second upper bridge arm switch tube and the collector of the second lower bridge arm switch tube are connected to one electrode of the battery; the base of the second upper bridge arm switch tube and the second lower bridge arm switch tube are not connected; One end of the filter capacitor, the base of the first upper bridge arm switch tube, the base of the second upper bridge arm switch tube and the base of the third upper bridge arm switch tube are connected; the emitter of the first lower bridge arm switch tube, the other end of the filter capacitor, the emitter of the second lower bridge arm switch tube, the other end of the battery and the emitter of the third lower bridge arm switch tube are connected; The controllable rectifier module further includes a first resistor and a first inductor connected in series, one end of the first resistor is connected to the power input end, the other end of the first resistor is connected to the first inductor, and the first inductor, the emitter of the first upper bridge arm switch tube, and the collector of the first lower bridge arm switch tube are connected; The battery charging and discharging module further includes a second inductor, one end of which is connected to one electrode of the battery, and the other end of which is connected to the emitter of the second upper bridge arm switch tube and the collector of the second lower bridge arm switch tube; The inverter voltage stabilization module also includes a third inductor and a grounding capacitor, one end of the third inductor is connected to the emitter of the third upper bridge arm switch tube and the collector of the third lower bridge arm switch tube, and the other end of the third inductor is connected to the power output end, and the power output end is grounded through the grounding capacitor.

8. The single-phase uninterruptible power supply circuit output voltage stabilization control system according to claim 7, characterized in that: The voltage equation is: In the above formula, L3 is the inductance of the third inductor, D is in the range of 0 to 1, and T on The duration of the third upper bridge arm switch tube being turned on and the third lower bridge arm switch tube being turned off, T off The duration of the third upper bridge arm switch tube being turned off and the third lower bridge arm switch tube being turned on.

9. The single-phase uninterruptible power supply circuit output voltage stabilization control system according to claim 8, characterized in that: The output voltage V0(k) and duty cycle D at time k, the output current I0(k) at time k, and the DC bus voltage V at time k dc The relationship between the output current I0(k-1) at time (k) and time k-1 is: In the above formula, T s is the sampling period, T s =T on +T off .

10. The single-phase uninterruptible power supply circuit output voltage stabilization control system according to claim 9, characterized in that: The optimal duty cycle is:

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