TW202324876A - Power conversion system with ripple injection and power conversion control method - Google Patents

Abstract

A power conversion system with ripple injection includes an AC-DC conversion unit, a voltage regulation unit, at least one DC-DC conversion unit, at least one load, and a first control unit. The AC-DC conversion unit has a first input side and a first output side, and the first input side receives an AC power to provide an input power. The voltage regulation unit is connected to the first output side and provides a DC link, and receives one part of the input power as an energy storage power. The at least one DC-DC conversion unit has a second input side and a second output side, and the second input side is connected to the DC link to receive the other part of the input power as an output power. The at least one load is connected to the second output side to receive the output power for being supplied power. The first control unit is connected to the DC link, the at least one DC-DC conversion unit, and the at least one load. The first control unit controls the at least one DC-DC conversion unit to adjust the magnitude of the ripple of the output power to perform a ripple injection operation to the at least one load according to the magnitude of the ripple of the input power.

Description

Power conversion system with ripple injection and power conversion control method

The present invention relates to a power conversion system and a power conversion control method, especially a power conversion system with ripple injection and a power conversion control method.

The input power of the power conversion system includes a DC component and a ripple component, part of which flows into the capacitor of the DC-Link, and the other part flows into the subsequent battery charger. In the traditional method, the battery charger charges the battery with a constant current, in which the output power is a fixed value, and only the DC component of the input power can be consumed, and all the ripple (AC) components of the input power will flow into the DC link. In the capacitor, the capacitor voltage ripple is large, which easily leads to damage to the capacitor. Furthermore, if the input power fluctuations cause excessive voltage ripples on the DC link due to an abnormal grid, it is easy to trigger the overvoltage protection and cause the possibility of tripping the battery charging (replacing) station.

For this reason, how to design a power conversion system and power conversion control method, especially a power conversion system and power conversion control method with ripple injection, to solve the problems and technical bottlenecks in the existing technology, is the inventor of this case. important topic of research.

An object of the present invention is to provide a power conversion system with ripple injection to solve the problems in the prior art.

To achieve the aforementioned object, the power conversion system with ripple injection proposed by the present invention includes an AC-DC conversion unit, a voltage stabilization unit, at least one DC-DC conversion unit, at least one load and a first control unit. The AC-DC conversion unit has a first input side and a first output side, and the first input side is coupled to an AC power supply to provide input power. The voltage stabilizing unit is coupled to the first output side, provides a DC link, and receives a part of the input power as energy storage power. Each DC-DC conversion unit has a second input side and a second output side, the second input side is coupled to the DC link, and receives another part of the input power as the output power. At least one load is coupled to the second output side, and correspondingly receives the power supplied by the received output power of at least one DC-DC conversion unit. The first control unit is coupled to the DC link, the DC-DC conversion unit and at least one load. The first control unit controls at least one DC-DC conversion unit to adjust the ripple of the output power according to the ripple of the input power, and performs a ripple injection operation on at least one load.

In one embodiment, when the first control unit determines that the DC link voltage is greater than or equal to the threshold voltage, the ripple injection operation is started.

In one embodiment, at least one DC-DC conversion unit collectively and averagely adjusts the ripple size of the output power.

In one embodiment, at least one DC-DC conversion unit operates at a constant current, and the first control unit controls at least one DC-DC conversion unit to perform a current ripple injection operation.

In one embodiment, at least one DC-DC conversion unit operates at a constant voltage, and the first control unit controls at least one DC-DC conversion unit to perform a voltage ripple injection operation.

In one embodiment, the first control unit determines a phase angle of a power ripple input to the DC link, and initiates a ripple injection operation according to the matched power ripple phase angle.

In one embodiment, the power conversion system with ripple injection further includes a second control unit. The second control unit is coupled to the AC-DC conversion unit and the DC link, and receives the AC power. When the AC power supply is a three-phase AC power supply, the second control unit controls the three-phase current of an AC input current flowing into the AC-DC conversion unit to be balanced and share current.

In one embodiment, the AC-DC conversion unit is a power factor corrector.

In one embodiment, the voltage stabilizing unit is a capacitor.

In one embodiment, at least one DC-DC conversion unit is a battery charger, and at least one load is a DC battery.

The technical effects are achieved by the proposed power conversion system with ripple injection: 1. Through the ripple injection control and compensation of the subsequent stage, the damage of the voltage stabilization unit (such as a capacitor) can be avoided or the protection mechanism can be activated to protect the capacitor, which can improve DC link capacitor life, and reduce maintenance circuit costs; 2. Through the post-stage ripple compensation, the three-phase current balance of the front-stage PFC circuit can be optimized, thus reducing the electromagnetic interference (EMI) effect of the input current, a On the one hand, it can also reduce the harm to the power grid caused by current imbalance.

Another object of the present invention is to provide a power conversion control method to solve the problems in the prior art.

In order to achieve the purpose disclosed above, the power conversion control method proposed in the present invention operates the power conversion control method through a power conversion system. The power conversion system includes an AC-DC conversion unit, a voltage stabilizing unit, at least one DC-DC conversion unit, at least one load and a first control unit. The AC-DC conversion unit receives AC power and provides input power. The voltage stabilizing unit provides a DC link, and the input power of the receiving part is the energy storage power. Each DC-DC conversion unit is coupled to the DC link, and receives another part of input power as output power. The at least one load correspondingly receives power supplied by the output power (p _out ) of at least one DC-DC conversion unit. The power conversion control method includes steps: (a), the first control unit obtains the DC link voltage of the DC link; (b), the first control unit selects and executes load control or ripple injection control and Load control; (c), when the first control unit chooses to perform ripple injection control and load control, the first control unit forms a first DC-to-DC control command according to the load demand message and the DC link voltage, wherein the load demand message corresponds to at least A load needs to extract power from at least one DC-DC conversion unit; (d), when the first control unit chooses to only perform load control, the first control unit forms a second DC-to-DC control command according to the load demand message; ( e) at least one DC-DC conversion unit, according to the first DC-to-DC control command or the second DC-to-DC control command provided by the first control unit, correspondingly extracts power from the voltage stabilization unit and performs DC power conversion, so as to Supply power required by at least one load.

In one embodiment, in step (b), when the first control unit judges that the corresponding DC link voltage is greater than or equal to the threshold voltage, the ripple injection control is started.

In one embodiment, at least one DC-DC conversion unit collectively and averagely adjusts the ripple size of the output power.

In one embodiment, at least one DC-DC conversion unit operates at a constant current, and the first control unit controls at least one DC-DC conversion unit to perform current ripple injection control.

In one embodiment, at least one DC-DC conversion unit operates at a constant voltage, and the first control unit controls at least one DC-DC conversion unit to perform voltage ripple injection control.

In one embodiment, the first control unit judges the phase angle of the power ripple input to the DC link, and activates the ripple injection control according to the matched power ripple phase angle.

In one embodiment, the power conversion system further includes a second control unit. The second control unit is coupled to the AC-DC conversion unit and the DC link, and receives the AC power. The power conversion control method includes further steps: (f), when the AC power supply is a three-phase AC power supply, the second control unit controls the three-phase current of the AC input current flowing into the AC-DC conversion unit to be balanced and share current.

The technical effects are achieved by the proposed power conversion control method: 1. Through the ripple injection control compensation of the subsequent stage, the damage of the voltage stabilization unit (such as a capacitor) can be avoided or the protection mechanism can be activated to protect the capacitor, so that the capacitor of the DC link can be improved. 2. Through the ripple compensation of the rear stage, the three-phase current balance of the front stage PFC circuit can be optimized, so as to reduce the electromagnetic interference (EMI) effect of the input current, on the one hand, it can also reduce Minor harm to the grid due to current imbalance.

In order to further understand the technology, means and effects that the present invention adopts to achieve the predetermined purpose, please refer to the following detailed description and accompanying drawings of the present invention. It is believed that the purpose, characteristics and characteristics of the present invention can be obtained from this in depth and For specific understanding, however, the accompanying drawings are provided for reference and illustration only, and are not intended to limit the present invention.

Hereby, the technical content and detailed description of the present invention are described as follows in conjunction with the drawings.

Please refer to FIG. 1 , which is a block diagram of the first embodiment of the power conversion system with ripple injection according to the present invention. The power conversion system with ripple injection of the present invention mainly includes an AC-DC conversion unit 10 , a voltage stabilizing unit 20 , at least one DC-DC conversion unit 30 , at least one load 40 and a first control unit 50 . Wherein, the quantity of at least one load 40 corresponds to the quantity of at least one DC-DC conversion unit 30 .

The AC-DC conversion unit 10 has a first input side and a first output side. The first input side receives the AC power V _AC and provides input power p _in . Wherein, in the applied embodiment, the AC power supply V _AC may be an AC power supply provided by a power grid, and the AC power supply V _{AC system} may be a three-phase AC power supply or a single-phase AC power supply, which will be described later. Incidentally, the input power _pin is uncontrollable, and it is related to the power supply of the grid. In addition, in the power conversion application of the present invention, the AC-DC conversion unit 10 is used as a power factor correction unit (or power factor correction device, power factor correction circuit) of power factor correction (PFC).

The voltage stabilizing unit 20 is coupled to the first output side of the AC-DC conversion unit 10 to provide a DC link L _DC (or called a DC bus), and receives a part of the input power _pin as energy storage power p _c , which means a part of The input power _pin is stored in the voltage stabilizing unit 20 . In one embodiment, the voltage stabilizing unit 20 is used as a capacitor for stabilizing voltage and storing energy.

Each DC-DC conversion unit 30 has a second input side and a second output side. The second input side is coupled to the direct current link L _DC and receives another part of the input power p _in to be the output power p _out . In one embodiment, the DC-DC conversion unit 30 is a battery charger, but the invention is not limited thereto. Incidentally, compared with the uncontrollable input power p _in , the output power p _out is controllable. Since the input power p _in is equal to the sum of the energy storage power p _c and the output power p _out , therefore, by controlling the size of the output power p _out , the size of the energy storage power p _c can be controlled accordingly, that is, the energy storage power p _c = Input power p _in - output power p _out . In other words, in order to control the output power p _out , it is necessary to know the amount of the input power pin, so _the present invention further detects the size _of the input power pin, and further based on the detected ripple size of the _input power pin Perform the ripple injection operation, which will be explained later.

Based on the aforementioned power conversion system of the present invention, the input power _pin has a ripple component, and when passing through the _{voltage stabilizing unit 20, the energy storage power p c distributed} by the input power pin and the output power p _out also correspond to each other with a rippling component. Among them, in order to achieve better ripple injection compensation, if the ripple component carried by the output power p _out is controlled as close as possible to the ripple component carried by the input power p _in , then the ripple carried by the energy storage power p _c The ripple component can be relatively small, and the voltage stabilizing unit 20 is least affected by the ripple component, so as to protect the voltage stabilizing unit 20 or reduce its loss rate.

At least one load 40 is coupled to the second output side of the DC-DC conversion unit 30 and correspondingly receives at least one power supply from the output power p _out of the DC-DC conversion unit 30 . In one embodiment, corresponding to the DC-DC conversion unit 30 being a battery charger, the at least one load 40 is a DC battery (charged by the battery charger), and if there are plural numbers, the DC batteries are For parallel coupling (connection) connection.

The first control unit 50 is coupled to the DC link L _DC , at least one DC-DC conversion unit 30 and at least one load 40 . By detecting the voltage v _dc of the DC link L _DC (i.e. the voltage across the DC link L _DC ) and the DC link input current i _dc (i.e. the current flowing into the DC link L _DC ), and calculating the product of the two, we can know (Detection) The magnitude of the input power p _in , that is, the input power p _in = voltage v _dc × current i _dc . Wherein, the calculation of the _input power pin can be implemented directly inside the first control unit 50 , or the power calculation result is provided to the first control unit 50 after the calculation is performed by an external calculation unit. Therefore, the first control unit 50 controls the DC-DC converting unit 30 to perform a ripple injection operation on at least one load 40 according to the magnitude of the ripple of the input power _pin , that is, the magnitude of the AC component of the _input power pin. Therefore, the first control unit 50 first determines whether to start (execute) the ripple injection operation according to the magnitude of the ripple of the input power _pin . If it is necessary to perform a ripple injection operation, then determine the amount of ripple power to be injected, as detailed below.

與交流成分的輸出功率

，其中直流成分的輸出功率

係用對至少一負載40進行供電，而交流成分的輸出功率

係用以提供漣波注入的補償。 The output power p _out includes the output power of the DC component

Output Power with AC Component

, where the output power of the DC component

is used to supply power to at least one load 40, and the output power of the AC component

It is used to provide compensation for ripple injection.

可視為是弦波的形態，因此其大小會有正、負值的變化。因此，第一控制單元50需要進一步判斷輸入至直流鏈L _DC的輸入功率p _in漣波成分的相位角，使得根據相符的功率漣波相位角啟動漣波注入操作。換言之，若沒有對輸入功率p _in漣波成分的相位角進行判斷，並且在合適的相位角關係下啟動漣波注入控制，則會使得儲能功率p _c變大(例如當輸入功率p _in為正值而受控的輸出功率p _out為負值時，將使得儲能功率p _c變大)，而造成穩壓單元20受到漣波成分的損傷，反而與本發明要實現對其保護的精神相衝突。因此，在合適的相位角關係下啟動漣波注入控制，將會使得漣波注入控制的效果更加優化。 Furthermore, since the output power of the AC component

It can be regarded as the shape of a sine wave, so its size will have positive and negative changes. Therefore, the first control unit 50 needs to further determine the phase angle of the _ripple component of the input power pin input to the DC link L _DC , so as to start the ripple injection operation according to the matched power ripple phase angle. In other words, if the phase angle of the ripple component _of the input power pin is not judged, and the ripple injection control is started under an appropriate phase angle relationship, the energy storage power _pc will become larger (for example, when the input power _pin is When the controlled output power p _out is positive and the controlled output power is negative, it will make the energy storage power p _c become larger), and cause the voltage stabilizing unit 20 to be damaged by the ripple component, which is contrary to the spirit of the present invention to realize its protection Conflict. Therefore, starting the ripple injection control under a proper phase angle relationship will make the effect of the ripple injection control more optimized.

Please refer to FIG. 2 , which is a block diagram of the second embodiment of the power conversion system with ripple injection according to the present invention. The power conversion system with ripple injection of the present invention further includes a second control unit 60 . The second control unit 60 is coupled to the AC-DC conversion unit 10 and the DC link L _DC , and receives the AC power V _AC . When the AC power supply V _AC is a three-phase AC power supply, the second control unit 60 controls the three-phase current of the AC input current flowing into the AC-DC conversion unit 10 to be balanced and share current. Therefore, by controlling the three-phase currents to be equal, on the one hand, the electromagnetic interference (EMI) effect of the input current can be reduced, and on the other hand, the harm to the power grid caused by the current imbalance can be reduced. If the AC power source V _AC is a single-phase AC power source, the second control unit 60 does not need to control the current average.

Please refer to FIG. 3 , which is a block diagram of a power conversion system using a battery charging station as an application of the present invention. A part shown in Figure 3 (i.e. the part related to the three-phase PFC) is used as the three-phase current for controlling the AC input current flowing into the AC-DC conversion unit 10 for balancing current sharing, and the other part (i.e. the part related to the battery charger) ) is used for compensation control of ripple injection.

)，並利用振幅偵測計算三相電壓的振幅(

)。利用鎖相迴路對電網電壓進行鎖相，得到電網相位角(

)。偵測直流鏈電壓(

)，並利用平均電壓計算以計算出三相電壓的平均值(

)。用直流穩壓產生適當的直流功率命令(

)，以穩定三相電壓的平均值(

)。利用直流功率命令(

)、電網電壓振幅(

)、以及電網相位角(

)作為輸入，並用電流平衡控制計算出電流命令(

)，使三相電流大小相同。 In the three-phase PFC part: detect the three-phase voltage of the grid terminal (grid), the mains terminal (

), and use the amplitude detection to calculate the amplitude of the three-phase voltage (

). Use the phase-locked loop to lock the grid voltage to get the grid phase angle (

). Detection of DC link voltage (

), and use the average voltage calculation to calculate the average value of the three-phase voltage (

). Use a DC regulator to generate the appropriate DC power command (

), to stabilize the average value of the three-phase voltage (

). Using the DC power command (

), grid voltage amplitude (

), and grid phase angle (

) as input, and use the current balance control to calculate the current command (

), so that the three-phase currents have the same magnitude.

)作為回授，以電流命令(

)減去回授值，並輸入至PID控制，進行誤差放大之回授控制。將控制訊號傳送至PWM模組，並透過驅動將PWM訊號放大，以驅動三相PFC電路，此時PFC將從電網抽取適當功率，以補償電池充電器為直流電池充電所需之能量，進而穩定直流鏈(DC-Link)的平均電壓。 Detect the three-phase current of grid input (

) as a feedback to the current command (

) minus the feedback value, and input it to the PID control for feedback control of error amplification. Send the control signal to the PWM module, and amplify the PWM signal through the drive to drive the three-phase PFC circuit. At this time, the PFC will draw appropriate power from the grid to compensate for the energy required by the battery charger to charge the DC battery, thereby stabilizing The average voltage of the DC link (DC-Link).

)與充電電流(

)以了解第x個充電電池的狀況，用定電流命令決定其定電流充電的電流大小。 In the battery charger part: the battery charging (replacing) station has a total of n battery chargers and n rechargeable batteries. Every battery charger is a buck-type circuit, which is implemented by a buck converter. Detect the battery terminal voltage (

) and charging current (

) to understand the status of the xth rechargeable battery, use the constant current command to determine the current size of its constant current charging.

)，與主機(主控、Host)端提供的漣波電流大小(

)、相位角(

)，經過總電流命令決定最終的充電電流命令(

)。將充電電流命令(

)與回授的充電電流(

)相減並傳送至PID控制進行誤差放大。將控制訊號傳送至PWM模組，並透過驅動將PWM訊號放大，以驅動降壓型電路(降壓轉換器)，使其輸出適當之充電電流對電池充電。 The charging current command provided by the constant current command (

), and the ripple current provided by the host (master control, Host) side (

), phase angle (

), after the total current command determines the final charging current command (

). The charging current command (

) and feedback charging current (

) are subtracted and sent to the PID control for error amplification. The control signal is sent to the PWM module, and the PWM signal is amplified by the drive to drive the step-down circuit (buck converter) so that it outputs an appropriate charging current to charge the battery.

)與PFC注入直流鏈(DC-Link)的電流(

)，並且利用功率計算以計算其功率(

)。利用功率漣波相位計算以計算功率漣波的相位角(

)。設定使漣波電流的相位角(

)與功率漣波的相位角(

)相同，如此電池充電器才能有效透過注入漣波電流，將注入至直流鏈(DC-Link)的功率漣波轉移至後級，使直流鏈電壓漣波減小。 The host (main control, Host) detects the DC link voltage (

) and the current injected into the DC link (DC-Link) by the PFC (

), and use the power calculation to calculate its power (

). Use the power ripple phase calculation to calculate the phase angle of the power ripple (

). Set the phase angle of the ripple current (

) and the phase angle of the power ripple (

) is the same, so that the battery charger can effectively transfer the power ripple injected into the DC link (DC-Link) to the subsequent stage by injecting ripple current, so that the DC link voltage ripple is reduced.

)傳送至各個電池充電器。偵測直流鏈電壓(

)並用漣波計算以計算出其電壓漣波大小(

)。設定直流鏈電壓之閾值(

)，並用電壓漣波命令計算出適當的電壓漣波大小(

)。將電壓漣波大小(

)與電壓漣波大小(

)相減，得到其誤差(

)。 Using a digital-to-analog converter, the phase angle of the ripple current (

) to each battery charger. Detection of DC link voltage (

) and use the ripple calculation to calculate its voltage ripple size (

). Set the threshold of the DC link voltage (

), and use the voltage ripple command to calculate the appropriate voltage ripple size (

). The voltage ripple size (

) and voltage ripple size (

) to get the error (

).

)為負值，代表直流鏈電壓尚未大過閾值(

)，此時無須降低漣波電壓，所以漣波電流大小(

)設為0。若誤差(

)為正值，代表電壓漣波過大，使直流鏈電壓大於閾值(

)，此時將用PID控制器將誤差(

)放大，得到所需之

，使直流鏈電壓能夠低於閾值(

)。 In the current ripple command, if the error (

) is a negative value, which means that the DC link voltage has not yet exceeded the threshold (

), there is no need to reduce the ripple voltage at this time, so the ripple current (

) is set to 0. If the error (

) is a positive value, which means that the voltage ripple is too large, making the DC link voltage greater than the threshold (

), then the PID controller will be used to convert the error (

) zoom in to get the desired

, so that the DC link voltage can be lower than the threshold (

).

與限制(limitation)，為

設定一個上限(

)，當計算之

大於

，則最終的漣波電流命令將被限制為

。最後透過通訊將

傳送至各個電池充電器。 Because the battery charger charges the battery with a constant current, the ripple current should not be too large, so use

and limitation (limitation), for

Set an upper limit (

), when calculating the

more than the

, then the final ripple current command will be limited to

. Finally, through communication, the

sent to each battery charger.

4A to FIG. 4C , which are schematic diagrams of waveforms for ripple injection control judgment in the present invention. The voltage v _dc shown in FIG. 4A is the magnitude of the voltage ripple across the DC link L _DC . In this embodiment, the voltage v _dc is compared with the over-voltage protection voltage OVP, once the voltage v _dc reaches or exceeds the over-voltage protection voltage OVP, the over-voltage protection will be activated to shut down the system. An embodiment of the present invention for judging the timing of ripple injection can compare the voltage v _dc with the threshold voltage v _dc,th : when the voltage v _dc is greater than or equal to the threshold voltage v _dc,th , the ripple injection compensation is started , On the contrary, if the voltage v _dc is less than the threshold voltage v _dc,th , the ripple injection compensation will be stopped. As shown in Figure 4B and Figure 4C, when the voltage v _dc is greater than or equal to the threshold voltage v _dc,th , the ripple injection compensation is started, so the voltage v _dc will gradually decrease, that is, the voltage v _dc is greater than the threshold voltage v _{dc , the smaller the part of th} (as shown in Figure 4B). At this time, since the voltage v _dc is still greater than or equal to the threshold voltage v _dc,th , the ripple injection compensation operation continues. Until the voltage v _dc is lower than the threshold voltage v _dc,th , the ripple injection compensation is stopped (as shown in FIG. 4C ).

Taking the application of a battery charger (that is, at least one DC-DC conversion unit 30) and a DC battery (that is, at least one load 40) as an example, the number of the battery charger and the DC battery is usually plural. Therefore, in the ripple injection control, The DC-DC conversion units 30 jointly and averagely adjust the ripple size of the output power p _out . Furthermore, since the implementation of the ripple injection compensation is related to the conversion power provided by the DC-DC conversion units 30 (that is, the ripple injection compensation is limited by the maximum output power of each DC-DC conversion unit 30), Therefore, therefore, the ripple injection compensation performed under the condition of being limited to the maximum output power of the DC-DC conversion unit 30 can be continuously performed as long as it is ensured that the voltage v _dc does not reach or exceed the over-voltage protection voltage OVP avoiding system shutdown.

Incidentally, for power supply applications of different load types, if at least one DC-DC conversion unit 30 operates at a constant current, the first control unit 50 controls at least one DC-DC conversion unit 30 to perform current ripple. Wave injection control. Furthermore, if at least one DC-DC conversion unit 30 operates at a constant voltage, the first control unit 50 controls at least one DC-DC conversion unit 30 to perform voltage ripple injection control. Therefore, the compensation control with ripple injection provided by the present invention can include the compensation control of current ripple injection and the compensation control of voltage ripple injection, depending on the load type of the power supply.

Please refer to FIG. 5 , which is a flow chart of the power conversion control method of the present invention. The power conversion control method of the present invention is operated through a power conversion system. Wherein, the main structure of the power conversion system can be referred to above, and will not be repeated here. The power conversion control method includes steps: firstly, the first control unit obtains the DC link voltage of the DC link (S11). Then, the first control unit selects to perform load control or to perform ripple injection control and load control according to the threshold voltage and the DC link voltage ( S12 ). If the first control unit only chooses to perform load control, then ripple injection control is not performed, that is, power conversion performed by the power conversion system for supplying power to at least one load 40 . If the first control unit chooses to perform the ripple injection control and the load control at the same time, it means that in addition to the power conversion performed by the power conversion system for supplying power to at least one load 40, the ripple injection control for the protection provided by the voltage stabilizing unit 20 is also Execute at the same time.

When the first control unit 50 selects to perform ripple injection control and load control, the first control unit 50 forms a DC link voltage according to the load demand information provided by at least one load 40 (for example, the power supply required by at least one load 40 ) and the DC link voltage. The first DC-to-DC control instruction. The load demand message corresponds to the power required by at least one load 40 to be extracted from at least one DC-DC conversion unit 30 ( S13 ).

When the first control unit 50 chooses to only perform load control, the first control unit 50 forms a second DC-to-DC control instruction according to the load demand information (S14).

Finally, at least one DC-DC conversion unit 30 extracts power from the voltage stabilizing unit 20 according to the first DC-to-DC control command or the second DC-to-DC control command provided by the first control unit 50, and performs DC power conversion. , so as to supply the power required by at least one load 40 (S15).

In summary, the present invention has the following features and advantages:

1. Through the post-stage ripple injection control compensation, the damage of the voltage stabilizing unit (such as a capacitor) can be avoided or the protection mechanism can be activated to protect the capacitor, which can increase the life of the capacitor in the DC link and reduce the maintenance cost of the circuit.

2. Through the ripple compensation of the latter stage, the three-phase current balance of the front-stage PFC circuit can be optimized, so as to reduce the electromagnetic interference (EMI) effect of the input current, and on the one hand, it can also reduce the impact on the power grid due to current imbalance. hazards.

The above is only a detailed description and drawings of preferred embodiments of the present invention, but the features of the present invention are not limited thereto, and are not intended to limit the present invention. As the standard, all embodiments that conform to the spirit of the patent scope of the present invention and its similar changes should be included in the scope of the present invention. Any person familiar with the art can easily think of changes or Modifications can all be covered by the patent scope of the following case.

10: AC-DC conversion unit 20: voltage stabilization unit 30: DC-DC conversion unit 40: load 50: first control unit 60: second control unit V _AC : AC power supply p _in : input power p _out : output power p _c : energy storage power L _DC : DC link v _dc : DC link voltage i _dc : DC link input current v _dc,th : threshold voltage OVP: overvoltage protection voltage S11~S15: steps

FIG. 1 is a block diagram of the first embodiment of the power conversion system with ripple injection according to the present invention.

FIG. 2 is a block diagram of the second embodiment of the power conversion system with ripple injection according to the present invention.

FIG. 3 is a block diagram of the power conversion system for the application of the battery charging station according to the present invention.

4A-4C are schematic diagrams of waveforms of ripple injection control judgment in the present invention.

FIG. 5 is a flow chart of the power conversion control method of the present invention.

10: AC-DC conversion unit

20: voltage stabilizing unit

30: DC-DC conversion unit

40: load

50: The first control unit

60:Second control unit

V _AC : AC power

_pin : input power

p _out : output power

p _c : energy storage power

L _DC : DC link

v _dc : DC link voltage

i _dc : DC link input current

Claims (17)

A power conversion system with ripple injection, comprising: An AC-DC conversion unit having a first input side and a first output side, the first input side receives an AC power supply and provides an input power; a voltage stabilizing unit, coupled to the first output side, providing a DC link, and receiving a part of the input power as an energy storage power; At least one DC-DC conversion unit, each DC-DC conversion unit has a second input side and a second output side, the second input side is coupled to the DC link, and receives another part of the input power as an output power ; At least one load, coupled to the second output side, correspondingly receives the power supply of the output power of the at least one DC-DC conversion unit; and a first control unit, coupled to the DC link, the at least one DC-DC conversion unit and the at least one load; Wherein, the first control unit controls the at least one DC-DC conversion unit to adjust the ripple of the output power according to the ripple of the input power, and performs a ripple injection operation on the at least one load. The power conversion system with ripple injection according to claim 1, wherein the first control unit starts the ripple injection operation when it determines that a DC link voltage is greater than or equal to a threshold voltage. The power conversion system with ripple injection as claimed in claim 2, wherein the at least one DC-DC conversion unit jointly and averagely adjusts the ripple size of the output power. The power conversion system with ripple injection as described in Claim 1, wherein the at least one DC-DC conversion unit operates at a constant current, and the first control unit controls the at least one DC-DC conversion unit to perform a current ripple injection operate. The power conversion system with ripple injection as described in Claim 1, wherein the at least one DC-DC conversion unit operates at a constant voltage, and the first control unit controls the at least one DC-DC conversion unit to perform a voltage ripple injection operate. The power conversion system with ripple injection as described in Claim 1, wherein the first control unit judges a phase angle of a power ripple input to the DC link, and activates the ripple according to the phase angle of the power ripple that matches Inject operation. The power conversion system with ripple injection as described in Claim 1 further includes: a second control unit, coupled to the AC-DC conversion unit and the DC link, to receive the AC power; Wherein, when the AC power supply is a three-phase AC power supply, the second control unit controls the three-phase current of an AC input current flowing into the AC-DC conversion unit to be balanced and share current. The power conversion system with ripple injection as claimed in Claim 1, wherein the AC-DC conversion unit is a power factor corrector. The power conversion system with ripple injection as described in Claim 1, wherein the voltage stabilizing unit is a capacitor. The power conversion system with ripple injection according to claim 1, wherein the at least one DC-DC conversion unit is a battery charger, and the at least one load is a DC battery. A power conversion control method is operated through a power conversion system, wherein the power conversion system includes: An AC-DC conversion unit receives an AC power supply and provides an input power; a voltage stabilizing unit providing a DC link and receiving a portion of the input power as an energy storage power; At least one DC-DC conversion unit, each of the DC-DC conversion units is coupled to the DC link, and receives another part of the input power as an output power; At least one load correspondingly receives the power supply of the output power of the at least one DC-DC conversion unit; and a first control unit; Wherein, the power conversion control method includes steps: (a), the first control unit obtains a DC link voltage of the DC link; (b), the first control unit selects to perform a load control or to perform a ripple injection control and the load control according to a threshold voltage and the DC link voltage; (c) When the first control unit selects to execute the ripple injection control and the load control, the first control unit forms a first DC-to-DC control command according to a load demand message and the DC link voltage, wherein the load The demand information corresponds to the power extracted from the at least one DC-DC conversion unit required by the at least one load; (d) When the first control unit chooses to only execute the load control, the first control unit forms a second DC-to-DC control command according to the load demand message; and (e), the at least one DC-DC conversion unit correspondingly extracts power from the voltage stabilizing unit according to the first DC-to-DC control command or the second DC-to-DC control command provided by the first control unit, and Perform DC power conversion to supply the power required by the at least one load. The power conversion control method as claimed in claim 11, wherein in step (b), the first control unit starts the ripple injection control when it determines that the corresponding DC link voltage is greater than or equal to a threshold voltage. The power conversion control method as claimed in claim 12, wherein the at least one DC-DC conversion unit jointly and averagely adjusts the ripple size of the output power. The power conversion control method according to claim 11, wherein the at least one DC-DC conversion unit operates at a constant current, and the first control unit controls the at least one DC-DC conversion unit to perform a current ripple injection control. The power conversion control method according to claim 11, wherein the at least one DC-DC conversion unit operates at a constant voltage, and the first control unit controls the at least one DC-DC conversion unit to perform a voltage ripple injection control. The power conversion control method according to claim 11, wherein the first control unit judges a phase angle of a power ripple input to the DC link, and activates the ripple injection control according to the phase angle of the power ripple. According to the power conversion control method described in Claim 11, the power conversion system further includes: a second control unit, coupled to the AC-DC conversion unit and the DC link, to receive the AC power; Wherein, the power conversion control method includes further steps: (f) When the AC power supply is a three-phase AC power supply, the second control unit controls the three-phase current of an AC input current flowing into the AC-DC conversion unit to be balanced and share current.

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