A bidirectional DCDC battery management device for off-peak power consumption and a control method thereof

Abstract

The present invention discloses a bidirectional DCDC battery management device for off-peak power consumption and a control method thereof, comprising a power unit, a control power supply, a voltage detection circuit, a current sensor, a drive circuit, an MCU control unit and a host computer. The present invention can realize off-peak power consumption, charge the battery in a closed-loop current according to the charging U-I curve without being affected by the bus voltage difference, discharge to the communication facility in a closed-loop voltage without being affected by the voltage difference, and easily realize charging and discharging and switching between boost or buck or mixed modes, so that the communication power supply is more energy-efficient, the battery charging is more reasonable, the output voltage is more stable, and the switching is simpler.

Description

Technical Field

[0001] The present invention relates to the technical field of communication power supplies, and in particular to a bidirectional DCDC battery management device for off-peak power consumption and a control method thereof. Background Art

[0002] Peak-shaving electricity consumption is the process of transferring part of the electricity consumption during peak periods to off-peak periods through technical, economic, and administrative means, reducing the peak-to-valley load difference of the power grid and optimizing resource allocation. It is of great significance to improving social and economic benefits and achieving the goal of "carbon neutrality".

[0003] The communication power supply is a voltage source for powering communication facilities, and is usually composed of an ACDC module, a backup battery, and a battery management device. The battery management device performs power supply switching, battery charging and discharging management of the ACDC module or battery. When the power grid has power, the ACDC module converts the AC power of the power grid into a DC voltage of 45-53V, outputs it to the communication facilities, and provides charging power for the backup battery; at this time, the battery management device draws power from the ACDC module to charge the backup battery. When the power grid loses power, the backup battery supplies power to the communication facilities through the isolation diode of the battery management device. However, the existing battery management device of the communication power supply has the shortcomings of not being able to stagger the peak power consumption, the battery charging is not saturated and the discharge is insufficient, the charging current control is extensive, and it is inconvenient to stabilize the voltage when the battery is powered. Specifically, it is manifested as:

[0004] First, the communication power supply is equipped with a large-capacity backup battery, which is capable of shifting power consumption during peak hours. It is a pity to use it only for power outage emergencies but not for shifting power consumption during peak hours.

[0005] Secondly, battery charging usually draws power from a 45-53V ACDC module, and the voltage of the backup battery is about 48V. The voltage difference between the two is small or even non-existent, so the charging current is small, the charging speed is slow, or even charging cannot occur, and the battery is prone to "not being fully charged". In addition, extensive control of the charging current rather than precise closed-loop control is not conducive to the battery's service life.

[0006] Third, communication facilities require a power supply voltage of about 45 to 53V, while the voltage of the backup battery is about 48V; when powered by a 48V backup battery, the inherent voltage drop of the isolation diode is also lost. If the backup battery voltage is slightly lower, it can no longer discharge to the communication facilities, so the battery's stored energy cannot be fully released.

[0007] Fourthly, when the communication power supply is powered by a backup battery, the output voltage is determined by the battery voltage and the inherent voltage drop of the isolation diode, and the output voltage cannot be closed-loop regulated.

[0008] In summary, a technical solution that can achieve peak-shifting electricity consumption, charge the battery in a current closed loop without being affected by the bus voltage difference, discharge to communication facilities in a voltage closed loop without being affected by the voltage difference, and easily realize charging and discharging and switching between boost or buck modes is urgently needed in this technical field. Summary of the invention

[0009] The present invention aims to solve the problems of inability to use electricity in a peak-shifting manner, insufficient battery charging and discharging, closed-loop control of charging current, and inconvenience in voltage stabilization when the battery is powered, and provides a bidirectional DCDC battery management device for peak-shifting power consumption and a control method thereof.

[0010] To solve the above problems, the present invention is achieved through the following technical solutions:

[0011] A control method for a bidirectional DCDC battery management device for off-peak power consumption comprises the following steps:

[0012] Step 1: The MCU control unit obtains initial parameters; the initial parameters include the grid period definition, the DC bus voltage expected value U 1s 、Battery target voltage U 2s , the optimal charging UI curve of the battery, the minimum voltage U allowed by the battery 2min , the maximum voltage allowed by the battery U 2max 、The maximum current allowed by the device is I max , the first voltage feedback coefficient K U1 , the second voltage feedback coefficient K U2 , Current feedback coefficient K I , and transition margin voltage ΔU;

[0013] Step 2: The MCU control unit obtains dynamic instructions and parameters; the dynamic instructions and parameters include the power grid information sent by the host computer, the current time obtained by the real-time clock of the MCU control unit, and the feedback current I collected by the current sensor. F , the DC bus feedback voltage U1 and the battery bus feedback voltage U2 collected by the voltage detection circuit, and the initial parameters with adjustment requirements dynamically transmitted from the host computer;

[0014] Step 3: The MCU control unit selects the battery charging or discharging mode according to whether there is an electric signal from the power grid, the current time, and the power grid period definition, namely:

[0015] When there is no electricity in the grid, or when there is electricity in the grid but the current time is at the peak of electricity consumption, select the battery discharge mode; otherwise, select the battery charging mode;

[0016] Step 4: The MCU control unit configures the correlation between the drive signals of transistors H1 to H4 output by the drive circuit and the PWM control signal output by the MCU control unit based on the DC bus feedback voltage U1 and the battery bus feedback voltage U2 collected in real time;

[0017] ① In the battery discharge mode:

[0018] When U2 ≤ U 2min At this time, transistors H1 to H4 are turned off; at this time, the MCU control unit issues an alarm for too low battery voltage;

[0019] When U2 ≤ U1 - ΔU, transistors H1 and H4 are turned off, the on / off of transistor H2 follows the PWM control signal, and transistor H3 is always on; at this time, the MCU control unit performs voltage closed-loop control for current limiting on the power unit;

[0020] When U1 - ΔU < U2 ≤ U1 + ΔU, transistor H1 is turned off, the on / off of transistor H2 follows the PWM signal, transistor H3 conducts at a fixed conduction rate, and the on / off of transistor H4 is opposite to that of transistor H3; at this time, the MCU control unit performs voltage closed-loop control for current limiting on the power unit;

[0021] When U2 > U1 + ΔU, transistors H1 and H2 are turned off, the on / off of transistor H3 follows the PWM control signal, and the on / off of transistor H4 is opposite to that of transistor H3; at this time, the MCU control unit performs voltage closed-loop control for current limiting on the power unit;

[0022] ② In the battery charging mode:

[0023] When U2 ≤ U1 - ΔU, the on / off of transistor H1 follows the PWM control signal, the on / off of transistor H2 is opposite to that of transistor H1, and transistors H3 and H4 are turned off; at this time, the MCU control unit performs current closed-loop control for voltage limiting on the power unit;

[0024] When U1 - ΔU < U2 ≤ U1 + ΔU, transistor H1 conducts at a fixed conduction rate, the on / off of transistor H2 is opposite to that of transistor H1, transistor H3 is turned off, and the on / off of transistor H4 follows the PWM signal; at this time, the MCU control unit performs current closed-loop control for voltage limiting on the power unit;

[0025] When U2 > U1 + ΔU, transistor H1 is always on, transistors H2 and H3 are turned off, and the on / off of transistor H4 follows the PWM control signal; at this time, the MCU control unit performs current closed-loop control for voltage limiting on the power unit;

[0026] When U2 ≥ U 2max Or U2 ≥ U 2SWhen , transistors H1~H4 are turned off; at this time, the battery does not need to be charged.

[0027] In battery discharge mode, when the MCU control unit implements current limiting voltage closed-loop control:

[0028] First, the MCU control unit sets the DC bus voltage expected value U 1s As the voltage loop setting value, the DC bus feedback voltage U1 and the first voltage feedback coefficient K U1 The product of the voltage loop is used as the voltage loop feedback value; the voltage loop PID operation is performed on the difference between the voltage loop set value and the voltage loop feedback value to obtain the current demand;

[0029] Then, the MCU control unit limits the current demand: if the current demand is greater than the maximum current allowed by the device I max , then the maximum allowable current of the device is I max as the current loop setting value; otherwise, the current demand is used as the current loop setting value;

[0030] Finally, the MCU control unit will feedback the current I F and current feedback coefficient K I The product of the two is used as the current loop feedback value, and the difference between the current loop set value and the current loop feedback value is used for current loop PID calculation to obtain the required pulse width. The MCU control unit outputs a PWM control signal corresponding to the opening width and the required pulse width.

[0031] In battery charging mode, the MCU control unit implements voltage-limited current closed-loop control:

[0032] First, the MCU control unit sets the battery target voltage U 2S As the voltage loop setting value, the battery bus feedback voltage U2 and the second voltage feedback coefficient K U2 The product of the voltage loop is used as the voltage loop feedback value; the voltage loop PID operation is performed on the difference between the voltage loop set value and the voltage loop feedback value to obtain the current demand;

[0033] Then, the MCU control unit queries the optimal charging UI curve of the battery according to the battery bus feedback voltage U2, and obtains the current corresponding to the battery bus feedback voltage U2 as the expected charging current I s-b ;

[0034] Next, the MCU control unit limits the current demand: if the current demand is greater than the expected charging current I s-b , then the expected charging current I s-b as the current loop setting value; otherwise, the current demand is used as the current loop setting value;

[0035] Finally, the MCU control unit will feedback the current IF and current feedback coefficient K I The product of the two is used as the current loop feedback value, and the difference between the current loop set value and the current loop feedback value is used for current loop PID calculation to obtain the required pulse width. The MCU control unit outputs a PWM control signal corresponding to the opening width and the required pulse width.

[0036] A bidirectional DCDC battery management device for off-peak power consumption that implements the above control method includes a power unit, a control power supply, a voltage detection circuit, a current sensor, a drive circuit, an MCU control unit and a host computer; the power unit is composed of transistors H1~H4, capacitors C1~C2, and an inductor L; the positive electrode of capacitor C1 and the drain of transistor H1 are connected to the positive electrode of the ACDC power module; the negative electrode of capacitor C1 and the source of transistor H2 are connected to the negative electrode of the ACDC power module; the positive electrode of capacitor C2 and the drain of transistor H3 are connected to the positive electrode of the backup battery; the negative electrode of capacitor C2 and the source of transistor H4 are connected to the negative electrode of the backup battery; the source of transistor H2 is connected to the source of transistor H4; the source of transistor H1 and the drain of transistor H2 are connected to one end of the inductor L, and the source of transistor H3 and the drain of transistor H4 are connected to the other end of the inductor L; the positive electrode of the ACDC power module is connected to the positive electrode of the backup battery via diode D1 A power input terminal of the control power supply is connected; the positive electrode of the backup battery is connected to the other power input terminal of the control power supply via a diode D2; the three groups of power output terminals of the control power supply are respectively connected to the power terminals of the voltage detection circuit, the drive circuit and the MCU control unit; a signal input terminal of the voltage detection circuit is connected to the positive electrode of the ACDC power module; the other signal input terminal of the voltage detection circuit is connected to the positive electrode of the backup battery; the two signal output terminals of the voltage detection circuit are respectively connected to the two voltage feedback input terminals of the MCU control unit; the signal acquisition terminal of the current sensor is located between the source electrodes of the transistors H1 and H3 of the power unit; the signal output terminal of the current sensor is connected to the current feedback input terminal of the MCU control unit; the control input terminal of the MCU control unit is connected to the host computer, the control output terminal of the MCU control unit is connected to the control input terminal of the drive circuit, and the four control terminals of the drive circuit are respectively connected to the gates of the four transistors H1 to H4.

[0037] In the above solution, transistors H1 to H4 are insulated gate bipolar transistors or field effect transistors.

[0038] In the above solution, the current sensor is a Hall current sensor.

[0039] In the above scheme, the host computer is connected to the MCU control unit through a bus control interface and an I / O control interface.

[0040] Compared with the prior art, the present invention has the following characteristics:

[0041] 1. By supplying power from backup batteries during peak hours and charging the batteries during off-peak hours, and by setting the target charging voltage for each period and selecting the amount of charging for each period, peak-shifting power consumption is achieved, making the communication power supply operation more economical.

[0042] 2. Regardless of the DC bus voltage, it can be charged in buck, boost or mixed mode, and can charge the battery in a closed-loop current according to the pre-stored battery charging UI curve as the set current, which not only solves the problem of "undercharged" batteries, but also solves the problem of charging current closed-loop control being more friendly to backup batteries and extending battery life.

[0043] 3. When the battery voltage is not lower than the minimum allowable value, regardless of the battery voltage, it can be discharged to the DC bus in buck, boost or mixed mode, fully releasing the battery's stored energy; because the DC bus feedback voltage is closed-loop controlled, regardless of the battery voltage, the communication power supply output voltage can be stabilized at the expected value.

[0044] 4. Charging and discharging, buck-boost and mixed mode switching are achieved by configuring the association between the H-bridge transistor drive signal and the PWM signal through software, and the switching is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 The electrical block diagram of a bidirectional DCDC battery management device for off-peak power consumption.

[0046] Figure 2 The present invention is a flow chart of a control method of a bidirectional DCDC battery management device for off-peak power consumption.

[0047] Figure 3 This is the battery discharge mode control flow chart.

[0048] Figure 4 This is the control flow chart for battery charging mode.

[0049] Figure 5 This is the schematic diagram of voltage closed-loop control with current limitation.

[0050] Figure 6 This is the schematic diagram of current closed-loop control with voltage limitation. DETAILED DESCRIPTION

[0051] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific examples.

[0052] See also Figure 1 A bidirectional DCDC battery management device for off-peak power consumption includes a power unit, a control power supply, a voltage detection circuit, a current sensor, a drive circuit, an MCU control unit and a host computer.

[0053] The power unit is composed of transistors (IGBT) H1~H4, capacitors C1~C2, and inductor L. Transistors H1~H4 form an H bridge. Transistors H1~H2 and capacitor C1 form the DC bus side. Transistors H3~H4 and capacitor C2 form the battery bus side. The positive electrode of capacitor C1 and the drain of transistor H1 are connected to the positive electrode of the ACDC power module; the negative electrode of capacitor C1 and the source of transistor H2 are connected to the negative electrode of the ACDC power module. The positive electrode of capacitor C2 and the drain of transistor H3 are connected to the positive electrode of the backup battery; the negative electrode of capacitor C2 and the source of transistor H4 are connected to the negative electrode of the backup battery. The source of transistor H2 is connected to the source of transistor H4. The source of transistor H1 and the drain of transistor H2 are connected to one end of inductor L, and the source of transistor H3 and the drain of transistor H4 are connected to the other end of inductor L.

[0054] The ACDC power module supplies power to this device, and there is an equivalent isolation diode in the ACDC power module. The backup battery is a rechargeable battery equipped according to the required voltage and capacity. One power input terminal of the control power supply is connected to the cathode of the diode D1, and the anode of the diode D1 is connected to the positive pole of the ACDC power module; the other power input terminal of the control power supply is connected to the cathode of the diode D2, and the anode of the diode D2 is connected to the positive pole of the backup battery; the three groups of power output terminals of the control power supply are respectively connected to the power supply terminals of the voltage detection circuit, the drive circuit and the MCU control unit.

[0055] One signal input end of the voltage detection circuit is connected to the positive electrode of the ACDC power module (for collecting the DC bus feedback voltage U1), and the other signal input end of the voltage detection circuit is connected to the positive electrode of the backup battery (for collecting the battery bus feedback voltage U2); the two signal output ends of the voltage detection circuit are respectively connected to the voltage feedback input end of the MCU control unit. The signal acquisition end of the current sensor is located between the source electrodes of the transistors H1 and H3 of the power unit, and is connected in series or isolated and coupled with the inductor L; the signal output end of the current sensor is connected to the current feedback input end of the MCU control unit. In a preferred embodiment of the present invention, the current sensor is a Hall current sensor.

[0056] The control input end of the MCU control unit is connected to the host computer, the control output end of the MCU control unit is connected to the control input end of the drive circuit, and the four control ends of the drive circuit are respectively connected to the gates of the four transistors H1 to H4. In a preferred embodiment of the present invention, the MCU control unit is connected to the host computer through a bus control interface and an I / O control interface. The bus control interface is used as an interface connected to the host computer for exchanging control instructions and transmitting parameters for this device, and is a CAN bus control interface and / or a 485 bus control interface; the I / O control interface is used as a faster logic control signal interface for exchanging control logic signals with this device.

[0057] The MCU control unit contains a microprocessor MCU and its measurement and control interface circuits and storage circuits, and a real-time clock circuit that does not lose power. The microprocessor MCU and its measurement and control interface circuits and storage circuits are used to realize signal AD conversion and measure the DC bus feedback voltage U1, battery bus feedback voltage U2, and current feedback signal I F As well as controlling PWM generation, it also contains measurement and control software, pre-stored grid time period charging strategy table, battery parameters, etc.; the real-time clock circuit without power failure is used to obtain the current real-time moment and determine the grid power consumption period. First, the MCU control unit sets the relationship between the H-bridge IGBT drive signal and the PWM signal according to the grid power signal transmitted by the host computer, the real-time clock of this device and the pre-stored grid time period definition. When the grid is without power or has power and is in the peak power consumption period, the battery discharge mode is selected, and the battery charging mode is selected when the grid has power. Secondly, the MCU control unit selects the boost or buck mode by setting the relationship between the H-bridge IGBT drive signal and the PWM signal according to the difference between the actual DC bus voltage U1 and the actual battery bus voltage U2. After that, the MCU control unit uses the DC bus voltage expected value U1 that has been stored in advance or dynamically transmitted by the host computer. 1S The voltage setting value is taken as the current limit value, and the maximum current allowed by the device is taken as the current limit value, and the battery discharge is controlled according to the voltage closed-loop control algorithm with current limit; or, through the real-time clock and the pre-stored grid time period charging strategy table, the charging current setting value I is obtained according to the current battery bus actual voltage U2 and the battery charging UI curve transmitted from the host computer and pre-stored S , the charging target voltage value U for each period in the charging strategy table 2S As the limit value, I S To set the current value, the battery is charged according to a current closed-loop control algorithm with voltage limitation.

[0058] See also Figure 2 , a control method for a bidirectional DCDC battery management device for off-peak power consumption, comprising the following steps:

[0059] Step 1: The MCU control unit obtains initial parameters.

[0060] The initial parameters include the grid period definition, battery target voltage U 2s 、DC bus voltage expected value U 1s , the optimal charging UI curve of the battery, the minimum voltage U allowed by the battery 2min , the maximum voltage allowed by the battery U 2max 、The maximum current allowed by the device is I max , the first voltage feedback coefficient K U1 , the second voltage feedback coefficient K U2 , Current feedback coefficient K I, and the transition margin voltage ΔU. The initial parameters can be pre-stored in the MCU control unit, or dynamically transmitted to the MCU control unit by the host computer.

[0061] In this embodiment, the grid period definition and the battery target voltage U 2s Stored in the grid period charging strategy table shown in Table 1.

[0062] Table 1 Charging strategy table for power grid period

[0063]

[0064] Note: √ charging; × not charging

[0065] In this embodiment, the peak power consumption period is 10:00≤T<13:00 and 18:00≤T<21:00, the flat power consumption period is 07:00≤T<10:00 and 13:00≤T<18:00, and the valley power consumption period is 21:00≤T<7:00. 2S U 2S(1) =46.0V, U 2S(2) =50.0V, U 2S(3) =52.0V. Battery target voltage U 2s The level of can determine the amount of charging to be done, by adjusting the charging target voltage U in the valley, flat and peak periods of the grid in the grid period charging strategy table. 2s , it can achieve more charging, less charging or no charging during valley, flat and peak periods to achieve better economy.

[0066] Since the DC bus is connected to the positive pole of the ACDC power module, the positive pole line of the ACDC power module has an equivalent isolation diode, and the expected value of the DC bus voltage is U 1S When setting, it should be higher than the actual output voltage U0 of the ACDC power module by about the saturation voltage drop of the diode (0.3V to 0.7V) so as to block the output of the ACDC power supply when the battery is discharged. 1s =48.0V.

[0067] The optimal charging UI curve for the battery and the minimum voltage U allowed by the battery 2min and the maximum voltage allowed by the battery U 2max Provided by the manufacturer. In this embodiment, the maximum voltage allowed by the battery is U 2max =53.0V, the lowest voltage allowed by the battery is U 2min =45.0V, the charging UI curve is a charging current data table with battery voltage as the pointer.

[0068] The maximum current allowed by the device is I maxIt is determined according to the performance parameters of the power unit of the device. In this embodiment, the device allows a maximum current I max Take 150A.

[0069] The first voltage feedback coefficient K U1 , the second voltage feedback coefficient K U2 and current feedback coefficient K I It is determined according to the principle that the product of the AD conversion value corresponding to the feedback signal amplitude and the feedback coefficient is equal to the value corresponding to the set signal amplitude. U1 =1, the second voltage feedback coefficient K U2 =1, current feedback coefficient K I =1.

[0070] The transition margin voltage ΔU is usually 0-15% of the rated voltage of the battery. In this embodiment, the rated voltage of the battery is 48V, so ΔU is 2V.

[0071] Step 2: The MCU control unit obtains dynamic instructions and parameters.

[0072] Dynamic instructions and parameters include the information on whether there is power in the grid sent by the host computer, the current time obtained by the real-time clock of the MCU control unit, and the feedback current I collected by the current sensor. F , the DC bus feedback voltage U1 and the battery bus feedback voltage U2 collected by the voltage detection circuit, and the initial parameters that need to be adjusted dynamically transmitted from the host computer.

[0073] Step 3, the MCU control unit selects the battery charging or discharging mode according to whether there is an electric signal in the power grid, the current time and the definition of the power grid period, that is, when the power grid has no electricity, or the power grid has electricity but the current time is in the peak power consumption period, the battery discharging mode is selected; otherwise, the battery charging mode is selected.

[0074] Step 4: Based on the DC bus feedback voltage U1 and the battery bus feedback voltage U2, and based on Table 2, configure the association relationship between the drive signals of the transistors H1 to H4 and the PWM control signals output by the MCU control unit.

[0075] Table 2 Control methods for grid power supply and battery discharge

[0076]

[0077] Note: ○Follow PWM control signal; Opposite to the on-off of the tube on the same arm; ● Normal conduction (conducting within 1 cycle T); ■ Fixed on-rate conduction (conducting at a preset on-rate within cycle T, on-rate ε = on-time t / cycle T, such as being turned on at an on-rate of 70-90%, that is, the on-time t accounts for 70-90% of the cycle T); × Off.

[0078] ① In the battery discharge mode (see the appendix Figure 3 ):

[0079] (1) If U2 ≤ U 2min , the MCU control unit turns off all the IGBTs of the H-bridge, namely H1 to H4, according to Table 2, does not discharge, and gives an alarm for too low battery voltage.

[0080] (2) If U2 ≤ U1 - ΔU, the MCU control unit configures the relationship between the IGBT drive signal of the H-bridge and the PWM signal as boost discharge according to Table 2, that is: H1 and H4 are turned off, the on / off of H2 follows the PWM signal, and H3 is always on. The MCU control unit implements voltage closed-loop control with current limitation for the power unit.

[0081] (3) If U1 - ΔU < U2 ≤ U1 + ΔU, the MCU control unit configures the relationship between the IGBT drive signal of the H-bridge and the PWM signal as hybrid discharge according to Table 2, that is: H1 is turned off, the on / off of H2 follows the PWM signal, H3 conducts with a fixed conduction rate, and the on / off of H4 is opposite to that of H3. The MCU control unit implements voltage closed-loop control with current limitation for the power unit.

[0082] (4) If U2 > U1 + ΔU, the MCU control unit configures the relationship between the IGBT drive signal of the H-bridge and the PWM signal as buck discharge according to Table 2, that is: H1 and H2 are turned off, the on / off of H3 follows the PWM signal, and the on / off of H4 is opposite to that of H3. The MCU control unit implements voltage closed-loop control with current limitation for the power unit.

[0083] In the battery discharge mode, according to the difference between the actual voltage U1 of the DC bus and the actual voltage U2 of the battery bus, by setting the relationship between the IGBT drive signal of the H-bridge and the PWM signal, the boost, buck or hybrid mode is dynamically selected. As long as the battery voltage is not lower than the allowable minimum value U 2min , it can discharge to the DC bus, making full use of the stored energy of the battery; at the same time, because the closed-loop control is performed on the feedback voltage of the DC bus, the voltage is stabilized at the expected value U 1s ; The peak-shaving power consumption by the battery during peak electricity consumption periods is selected, and the operation is more economical; the switching to the boost, buck or hybrid mode is achieved by setting the relationship between the IGBT drive signal of the H-bridge and the PWM signal, and the switching is simple.

[0084] See Figure 5 , in the battery discharge mode, when the MCU control unit implements voltage closed-loop control with current limitation:

[0085] First, the MCU control unit takes the expected value U 1s of the DC bus voltage as the voltage loop set value, and takes the DC bus feedback voltage U1 and the first voltage feedback coefficient KU1 The product of the voltage loop is used as the voltage loop feedback value; the voltage loop PID operation is performed on the difference between the voltage loop set value and the voltage loop feedback value to obtain the current demand;

[0086] Then, the MCU control unit limits the current demand: if the current demand is greater than the maximum current allowed by the device I max , then the maximum allowable current of the device is I max as the current loop setting value; otherwise, the current demand is used as the current loop setting value;

[0087] Finally, the MCU control unit will feedback the current I F and current feedback coefficient K I The product of the two is used as the current loop feedback value, and the difference between the current loop set value and the current loop feedback value is used for current loop PID calculation to obtain the required pulse width. The MCU control unit outputs a PWM control signal with an opening width corresponding to the required pulse width (period is T).

[0088] During step-down discharge, H1 and H2 are turned off, the on-off of H3 follows the PWM signal, and the on-off of H4 is opposite to that of H3. The current I flowing through the inductor L is adjusted by adjusting the on-width of transistors H3 and H4. F During boost discharge, H1 and H4 are turned off, H2 is turned on and off following the PWM signal, and H3 is turned on. The current I flowing through the inductor L is adjusted by adjusting the opening width of transistor H2. F During mixed discharge, H1 is turned off, H2 is turned on and off following the PWM signal, H3 is turned on at a fixed opening rate, and H4 and H3 are turned on and off in opposite phases. By controlling transistor H3 to turn on at a fixed opening rate to achieve a fixed ratio voltage reduction, and adjusting the opening width of transistor H2 to adjust the current I flowing through the inductor L F By adjusting the current I F By adjusting the DC bus voltage U1 and controlling the current inner loop and voltage outer loop, a voltage closed-loop control with current limitation is realized, so that the DC bus voltage is stabilized at the expected value U 1s In this embodiment, U 1s =48.0V, the voltage regulation accuracy is better than 0.5%.

[0089] ② In battery charging mode (see attached Figure 4 ):

[0090] (1) If U2≤U1-ΔU, the MCU control unit configures the relationship between the H-bridge IGBT drive signal and the PWM signal as buck charging according to Table 2, that is, the on-off of H1 follows the PWM signal, the on-off of H2 and H1 are in reverse phase, and H3 and H4 are turned off. The MCU control unit implements current closed-loop control with voltage limitation on the power unit.

[0091] (2) If U1 - ΔU < U2 ≤ U1 + ΔU, the MCU control unit configures the relationship between the H-bridge IGBT drive signal and the PWM signal as hybrid charging according to Table 2, that is: H1 conducts with a fixed conduction rate, H2 is in an on-off state opposite to that of H1, H3 is off, and the on-off state of H4 follows the PWM signal. The MCU control unit implements voltage-closed-loop control for current limiting of the power unit.

[0092] (3) When U2 > U1 + ΔU, the MCU control unit configures the relationship between the H-bridge IGBT drive signal and the PWM signal as boost charging according to Table 2, that is: H1 conducts constantly, H2 and H3 are off, and the on-off state of H4 follows the PWM signal. The MCU control unit implements current-closed-loop control for voltage limiting of the power unit.

[0093] (4) If U2 ≥ U 2max or U2 ≥ U 2S , it indicates that the battery does not need to be charged, and the MCU control unit turns off all the IGBTs of the H-bridge, namely H1 to H4, according to Table 2.

[0094] In the battery charging mode, according to the difference between the actual voltage U1 of the DC bus and the actual voltage U2 of the battery bus, by setting the correlation between the H-bridge IGBT drive signal and the PWM signal, the boost, buck or hybrid mode is dynamically selected. Regardless of the level of the DC bus feedback voltage, the battery can be charged with the current according to the desired battery charging U-I curve, which not only solves the problem of the battery not being fully charged, but is also more friendly to the standby power; by setting the charging target voltage U 2s of the grid time period charging strategy table, more charging, less charging or no charging is selected during the valley, flat and peak periods of the grid, realizing off-peak power consumption and more economical operation; the switching between the boost, buck or hybrid charging modes is achieved by setting the correlation between the H-bridge IGBT drive signal and the PWM signal, and the switching is simple.

[0095] See Figure 6 , in the battery charging mode, when the MCU control unit implements current-closed-loop control with voltage limiting:

[0096] First, the MCU control unit takes the battery target voltage U 2S as the voltage loop set value, and takes the product of the battery bus feedback voltage U2 and the second voltage feedback coefficient K U2 as the voltage loop feedback value; and performs voltage loop PID operation on the difference between the voltage loop set value and the voltage loop feedback value to obtain the current demand I s-a ;

[0097] Then, the MCU control unit queries the optimal charging U-I curve of the battery according to the battery bus feedback voltage U2, and obtains the current corresponding to the battery voltage U2 as the desired charging current I s-b ;

[0098] Next, the MCU control unit limits the current demand: if the current demand is greater than the expected charging current I s-b , then the expected charging current I s-b As the current loop setting value Is; otherwise, the current demand I s-a As the current loop set value Is.

[0099] According to the PID regulation characteristics, the battery bus feedback voltage U2 and the battery target voltage U 2S When the deviation is large, the current demand obtained by the voltage loop PID calculation is relatively large, often much larger than the expected charging current I s-b Therefore, U2 approaches U 2S Before, the MCU control unit selects the desired charging current I s-b Is is the current loop setting value; U2 approaches U 2S After that, the voltage loop PID operation obtains the current demand I s-a Gradually decrease until it is less than the expected charging current I s-b , the MCU control unit selects the current demand I s-a As the current loop set value Is.

[0100] Finally, the MCU control unit will feedback the current I F and current feedback coefficient K I The product of the two is used as the current loop feedback value, and the difference between the current loop set value and the current loop feedback value is used for current loop PID calculation to obtain the required pulse width. The MCU control unit outputs a PWM control signal with an opening width corresponding to the required pulse width (period is T).

[0101] During buck charging, H3 and H4 are turned off, the on-off of H1 follows the PWM signal, and the on-off of H2 is opposite to that of H1. The current I flowing through the inductor L is adjusted by adjusting the on-width of transistors H1 and H2. F During boost charging, H1 is turned on, H2 and H3 are turned off, and the on and off of H4 follows the PWM signal. By adjusting the on width of transistor H4, the current I flowing through the inductor L is adjusted. F During hybrid charging, H1 is turned on at a fixed on-rate, H2 and H1 are turned on and off in opposite phases, H3 is turned off, and H4 follows the PWM signal. By controlling transistor H1 to turn on at a fixed on-rate to achieve a fixed ratio of voltage reduction, and adjusting the on-width of transistor H4 to adjust the current I flowing through the inductor L F By adjusting the current I F The battery bus voltage U2 is adjusted, and through the dual-loop control of the current inner loop and the voltage outer loop, charging the battery with voltage limitation and using the pre-stored battery charging UI curve as the current setting value is achieved.

[0102] The present invention can realize peak-shifting electricity consumption, charge the battery in a current closed loop without being affected by the bus voltage difference, discharge the communication facilities in a voltage closed loop without being affected by the voltage difference, and easily realize charging and discharging and switching between boosting, bucking or mixed modes, so that the communication power supply is more energy-efficient, the battery charging is more reasonable, the output voltage is more stable, and the switching is simpler.

[0103] It should be noted that although the embodiments of the present invention described above are illustrative, they are not intended to limit the present invention, and therefore the present invention is not limited to the above specific embodiments. Without departing from the principles of the present invention, any other embodiments obtained by those skilled in the art under the guidance of the present invention are deemed to be within the protection of the present invention.

Claims

1. A control method for a bidirectional DCDC battery management device for off-peak power consumption, characterized in that: The steps are as follows: Step 1: The MCU control unit obtains initial parameters; the initial parameters include the grid period definition, the DC bus voltage expected value U 1s 、Battery target voltage U 2s , the optimal charging UI curve of the battery, the minimum voltage U allowed by the battery 2min , the maximum voltage allowed by the battery U 2max 、The maximum current allowed by the device is I max , the first voltage feedback coefficient K U1 , the second voltage feedback coefficient K U2 , Current feedback coefficient K I and transition margin voltage ΔU; Step 2: The MCU control unit obtains dynamic instructions and parameters; the dynamic instructions and parameters include the power grid information sent by the host computer, the current time obtained by the real-time clock of the MCU control unit, and the feedback current I collected by the current sensor. F , the DC bus feedback voltage U1, the battery bus feedback voltage U2 collected by the voltage detection circuit, and the initial parameters that need to be adjusted dynamically transmitted from the host computer; Step 3: The MCU control unit selects the battery charging or discharging mode according to the power signal of the power grid, the current time, and the power grid time period definition, that is: When there is no power in the power grid or there is power in the power grid but the current time belongs to the peak power consumption period, select the battery discharging mode; otherwise, select the battery charging mode; Step 4: The MCU control unit configures the association relationship between the drive signals of transistors H1~H4 output by the drive circuit and the PWM control signal output by the MCU control unit based on the DC bus feedback voltage U1 and the battery bus feedback voltage U2 collected in real time; In battery discharge mode: When U2≤U 2min When the battery voltage is too low, the transistors H1~H4 are turned off. At this time, the MCU control unit issues a low battery voltage alarm. When U2≤U1-ΔU, transistors H1 and H4 are turned off, the on / off of transistor H2 follows the PWM control signal, and transistor H3 is always on; at this time, the MCU control unit implements voltage closed-loop control with current limitation for the power unit; When U1-ΔU<U2≤U1+ΔU, transistor H1 is turned off, the on / off of transistor H2 follows the PWM signal, transistor H3 conducts with a fixed conduction rate, and the on / off of transistor H4 is opposite to that of transistor H3; At this time, the MCU control unit implements voltage closed-loop control with current limitation for the power unit; When U2>U1+ΔU, transistors H1 and H2 are turned off, the on / off of transistor H3 follows the PWM control signal, and the on / off of transistor H4 is opposite to that of transistor H3; At this time, the MCU control unit implements voltage closed-loop control with current limitation for the power unit; In battery charging mode: When U2≤U1-ΔU, the on / off of transistor H1 follows the PWM control signal, the on / off of transistor H2 is opposite to that of transistor H1, and transistors H3 and H4 are turned off; at this time, the MCU control unit implements current closed-loop control with voltage limitation for the power unit; When U1-ΔU<U2≤U1+ΔU, transistor H1 conducts with a fixed conduction rate, the on / off of transistor H2 is opposite to that of transistor H1, transistor H3 is turned off, and the on / off of transistor H4 follows the PWM signal; at this time, the MCU control unit implements current closed-loop control with voltage limitation for the power unit; When U2>U1+ΔU, transistor H1 is always on, transistors H2 and H3 are turned off, and the on / off of transistor H4 follows the PWM control signal; at this time, the MCU control unit implements current closed-loop control with voltage limitation for the power unit; When U2 ≥ U 2max Or U2 ≥ U 2S When , transistors H1~H4 are turned off; at this time, the battery does not need to be charged.

2. The control method of a bidirectional DCDC battery management device for off-peak power consumption as claimed in claim 1 is characterized in that In the battery discharging mode, when the MCU control unit implements voltage closed-loop control with current limitation: First, the MCU control unit sets the DC bus voltage expected value U 1s As the voltage loop setting value, the DC bus feedback voltage U1 and the first voltage feedback coefficient K U1 The product of the voltage loop is used as the voltage loop feedback value; the voltage loop PID operation is performed on the difference between the voltage loop set value and the voltage loop feedback value to obtain the current demand; Then, the MCU control unit limits the current demand: if the current demand is greater than the maximum current allowed by the device I max , then the maximum allowable current of the device is I max as the current loop setting value; otherwise, the current demand is used as the current loop setting value; Finally, the MCU control unit will feedback the current I F and current feedback coefficient K I The product of the two is used as the current loop feedback value, and the difference between the current loop set value and the current loop feedback value is used for current loop PID calculation to obtain the required pulse width. The MCU control unit outputs a PWM control signal corresponding to the opening width and the required pulse width.

3. The control method of a bidirectional DCDC battery management device for off-peak power consumption as claimed in claim 1 is characterized in that: In the battery charging mode, when the MCU control unit implements current closed-loop control with voltage limitation: First, the MCU control unit sets the battery target voltage U 2S As the voltage loop setting value, the battery bus feedback voltage U2 and the second voltage feedback coefficient K U2 The product of the voltage loop is used as the voltage loop feedback value; the voltage loop PID operation is performed on the difference between the voltage loop set value and the voltage loop feedback value to obtain the current demand; Then, the MCU control unit queries the optimal charging UI curve of the battery according to the battery bus feedback voltage U2, and obtains the current corresponding to the battery bus feedback voltage U2 as the expected charging current I s-b ; Next, the MCU control unit limits the current demand: if the current demand is greater than the expected charging current I s-b , then the expected charging current I s-b as the current loop setting value; otherwise, the current demand is used as the current loop setting value; Finally, the MCU control unit will feedback the current I F and current feedback coefficient K I The product of the two is used as the current loop feedback value, and the difference between the current loop set value and the current loop feedback value is used for current loop PID calculation to obtain the required pulse width. The MCU control unit outputs a PWM control signal corresponding to the opening width and the required pulse width.

4. A bidirectional DCDC battery management device for off-peak power consumption that implements the control method of claim 1, characterized in that: It includes a power unit, a control power supply, a voltage detection circuit, a current sensor, a drive circuit, an MCU control unit, and a host computer; The power unit is composed of transistors H1~H4, capacitors C1~C2 and inductor L; the positive electrode of capacitor C1 and the drain of transistor H1 are connected to the positive electrode of the ACDC power module; the negative electrode of capacitor C1 and the source of transistor H2 are connected to the negative electrode of the ACDC power module; the positive electrode of capacitor C2 and the drain of transistor H3 are connected to the positive electrode of the backup battery; the negative electrode of capacitor C2 and the source of transistor H4 are connected to the negative electrode of the backup battery; the source of transistor H2 is connected to the source of transistor H4; The source of transistor H1 and the drain of transistor H2 are connected to one end of inductor L, and the source of transistor H3 and the drain of transistor H4 are connected to the other end of inductor L; The positive pole of the ACDC power module is connected to one power input terminal of the control power supply via a diode D1; the positive pole of the backup battery is connected to another power input terminal of the control power supply via a diode D2; the three groups of power output terminals of the control power supply are respectively connected to the power terminals of the voltage detection circuit, the drive circuit and the MCU control unit; One signal input terminal of the voltage detection circuit is connected to the positive electrode of the ACDC power module; another signal input terminal of the voltage detection circuit is connected to the positive electrode of the backup battery; two signal output terminals of the voltage detection circuit are respectively connected to two voltage feedback input terminals of the MCU control unit; The signal collection end of the current sensor is located between the sources of transistors H1 and H3 of the power unit; the signal output end of the current sensor is connected to the current feedback input end of the MCU control unit; The control input end of the MCU control unit is connected to the host computer, the control output end of the MCU control unit is connected to the control input end of the drive circuit, and the four control ends of the drive circuit are respectively connected to the gates of the four transistors H1 to H4.

5. A bidirectional DCDC battery management device for off-peak power consumption according to claim 4, characterized in that: The transistors H1 to H4 are insulated gate bipolar transistors or field effect transistors.

6. A bidirectional DCDC battery management device for off-peak power consumption according to claim 4, characterized in that: The current sensor is a Hall current sensor.

7. A bidirectional DCDC battery management device for off-peak power consumption according to claim 4, characterized in that: The host computer is connected to the MCU control unit via a bus control interface and an I / O control interface.

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