CN108964176A - A kind of grid-connected electric discharge device of storage battery activation - Google Patents

Abstract

The invention relates to a storage battery activation grid-connected discharge device, which includes a main circuit unit and a control unit, the main circuit unit includes a step-up circuit, an inverter circuit and a filter circuit connected in sequence, the battery is connected to the input end of the step-up circuit, and the filter circuit The output terminal is connected to the power grid, and the control unit includes a controller and a drive circuit, the controller is connected to the drive circuit, and the drive circuit is used to drive the power tubes in the boost circuit and the inverter circuit. The invention feeds back the electric energy of the accumulator to the power grid through a boost circuit, an inverter circuit and a filter circuit, replacing the traditional heat-generating discharge method, greatly reducing energy loss and complying with national energy-saving and emission-reduction policies.

Description

A storage battery activation grid-connected discharge device

This application is a divisional application of the following original application, the filing date of the original application: December 09, 2014, the application number of the original application: 201410753896.0, and the invention name of the original application: a battery activation grid-connected discharge device.

technical field

The invention relates to a storage battery activation grid-connected discharge device.

Background technique

In the industrial field, batteries have always played an important role as a backup power source. In the daily use and maintenance of the battery, in order to detect the state of the battery capacity and activate the battery, a discharge test must be carried out regularly. With the national policy of "energy saving and emission reduction" deeply rooted in the hearts of the people, energy-fed battery discharge devices have become a research hotspot in recent years.

The battery needs to be maintained for a period of time, and it needs to be charged and discharged for activation, and the battery also needs to be periodically discharged by nuclear capacity and internal resistance measurement. The traditional battery activation and discharge process is to consume electric energy through loads such as resistors and electric furnaces. This discharge method has the following disadvantages: (1) The energy of the battery is converted into heat energy and dissipated in the air, resulting in a huge waste of energy; (2) Due to a large amount of heat consumption, the temperature of the environment rises, and the heat dissipation treatment is cumbersome, which affects safety. (fire hazard and personal safety) and reduce the insulation of the equipment, accelerate the aging of the resistance, greatly reduce the reliability and safety of the device, and shorten the service life of the surrounding equipment; (3) the control of the discharge current of the battery is effective Level adjustment, so that the discharge accuracy is not high, and during the discharge process, with the change of the battery terminal voltage and the change of the resistance value with the temperature, the discharge current cannot be kept constant, causing a large deviation in the measurement results of the battery; (4) Energy-consuming components are often bulky and heavy, so the entire discharge device is bulky; (5) The labor intensity of maintenance personnel is high, and it is not suitable for completely unattended power stations.

Contents of the invention

The object of the present invention is to provide a storage battery activation grid-connected discharge device to solve the problem of energy waste caused by traditional discharge methods.

To achieve the above object, the solution of the present invention includes a storage battery activation grid-connected discharge device, including a main circuit unit and a control unit. The input terminal of the voltage circuit, the output terminal of the filter circuit is connected to the grid, the control unit includes a controller and a drive circuit, the controller is connected to the drive circuit, and the drive circuit is used to drive the power tubes in the LLC boost circuit and inverter circuit.

The control unit also includes a sampling circuit for collecting electrical parameters of the discharge device, a protection circuit for protecting the main circuit unit, and a communication circuit for external communication. The electrical parameters include at least the voltage of the battery, the current of the battery, and the DC bus Voltage, grid voltage and grid current, the protection of the main circuit unit at least includes the over/under voltage protection of the battery input voltage and the over/under voltage protection of the output grid voltage.

An EMI filter circuit is connected between the LLC boost circuit and the inverter circuit.

The discharge device also includes two auxiliary power supply units for providing operating voltage to the control unit: a first auxiliary power supply unit and a second auxiliary power supply unit, the input of the first auxiliary power supply unit is connected to the output terminal of the storage battery, and the input of the second auxiliary power supply unit is connected to power grid.

The discharge device also includes a man-machine interface unit for setting and displaying electrical parameters of the discharge device.

The LLC boost circuit is composed of three LLC resonant full-bridge boost circuits connected in parallel.

The invention feeds back the electric energy of the accumulator to the power grid through the LLC boost circuit, the inverter circuit and the filter circuit, replaces the traditional heat-generating discharge method, greatly reduces energy loss and conforms to the national energy-saving and emission-reduction policy.

In addition, the LLC boost circuit converts the low-voltage wide-range voltage of the battery into a higher DC bus voltage, and at the same time realizes the constant current discharge control of the battery; the filter circuit can effectively filter out high-frequency components.

Description of drawings

Fig. 1 is a schematic structural diagram of the principle of an embodiment of the present invention;

Fig. 2 is a schematic diagram of an LLC step-up circuit;

Fig. 3 is a schematic diagram of boost control;

Fig. 4 is a schematic diagram of an inverter circuit;

Fig. 5 is a schematic diagram of inverter control;

Fig. 6 is a schematic diagram of a filter circuit;

Fig. 7 is a schematic diagram of filtering control.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

A storage battery activation grid-connected discharge device, including a main circuit unit and a control unit, the main circuit unit includes an LLC boost circuit, an inverter circuit and a filter circuit connected in sequence, the battery is connected to the input end of the LLC boost circuit, and the output of the filter circuit The terminal is connected to the power grid, the control unit includes a controller and a drive circuit, the controller controls and connects the drive circuit, and the drive circuit is used to drive the power tubes in the LLC boost circuit and inverter circuit.

Based on the above technical solutions and in conjunction with the accompanying drawings, the following specific implementation is given.

As shown in Fig. 1, the battery activation grid-connected discharge device includes a main circuit unit, a control unit, an auxiliary power supply unit and a man-machine interface unit.

The main circuit unit includes an LLC step-up circuit, an inverter circuit and a filter circuit connected in sequence, the storage battery is connected to the input end of the LLC step-up circuit, and the output end of the filter circuit is connected to the grid.

The LLC boost circuit takes the LLC resonant full-bridge boost circuit as an example.

As shown in Figure 2, the LLC resonant full-bridge boost circuit converts the 40VDC-90VDC low-voltage wide-range input battery voltage into a 394VDC DC bus voltage, and at the same time realizes the constant current discharge control of the battery. The positive (VIN+) input of the three-way LLC resonant full-bridge booster circuit is connected to each other, the negative (VIN-) is connected to each other and respectively connected to the positive pole and the negative pole of the battery pack, the positive (VDC+) of the output is connected to each other, and the negative (VDC-) connected to each other.

As shown in Figure 3, after the actual discharge current is compared with the given discharge current, the error signal is sent to the PWM frequency modulation controller after passing through the PI regulator, and then the PWM frequency modulation controller generates a 0.5 frequency adjustable discharge current. PWM signal, the PWM signal is then controlled by the drive circuit to control the switching device COOLMOS of the boost circuit, so that the actual discharge current can track the given current, so as to achieve the purpose of constant current discharge. The total discharge current is evenly divided into three parts, which is a given discharge current for each LLC resonant full-bridge booster circuit, and the discharge current slowly reaches a given value.

Control the grid-connected current to track the command current, and control the DC bus voltage to stabilize, so as to achieve the purpose of high power factor and low harmonic pollution. As shown in Figure 4, an EMI filter circuit is added between the LLC resonant full-bridge boost circuit and the DC/AC inverter circuit, which can reduce the interference between the two-stage lines. The DC/AC inverter circuit also uses power tube IGBT parallel technology to increase the grid-connected discharge capacity.

As shown in Figure 5, the DC/AC inverter circuit adopts double-loop control, the DC voltage outer loop keeps the bus voltage at a constant 394V, and the output of the outer loop controller is used as the setting of the inner loop, that is, the amplitude command of the given current loop , while adding the feedforward of the grid voltage; the phase-locked loop keeps the grid-connected current at the same frequency and phase as the grid voltage, and the current inner loop controls the grid-connected current. The power factor to achieve grid connection is 0.99, the current PHD is less than 2%, the output current can reach 120A, and the grid voltage is synchronized with the inverter output voltage. Power grid feedforward control KPWM adopts PI+PR control strategy. The PR controller has infinite gain at the resonant frequency, but very small gain at the non-resonant place. It can increase the gain of the specified frequency, thereby strengthening the suppression of a certain harmonic.

As shown in Figure 6, the LCL filter is a third-order filter, which can effectively filter out the high-frequency components of the switching frequency, reduce the volume and weight of the passive component LCL, and have a good filtering effect. The parallel capacitance value of C1——C5 is C, and the parallel resistance value of R1——R5 is R.

The filter control is shown in Figure 7, L1, L2, C, R are L1, L2, C, R in Figure 6, Vr is the output signal of the voltage outer loop, and Vg is the grid voltage.

The parameter design of double-loop control is more complicated, but it can better suppress the resonance peak of LCL, increase the stability margin of the system, and is better than single-loop control in adaptability to different grid conditions.

The control unit includes a main controller, a driving circuit, a sampling circuit, a protection circuit and a communication circuit, the main controller is connected to the driving circuit, the protection circuit and the communication circuit, and the main controller is connected to the sampling circuit for sampling. There can be only one sampling circuit, and in order to reduce the workload of one sampling circuit, two sampling circuits can also be set to divide the work for collection.

The main controller includes the following parts: control chip L6599, DSP control chip TMS320F2812 and control chip PIC16F877A.

The driving circuit realizes the driving of the power tube of the LLC step-up circuit and the driving of the power tube of the DC/AC inverter circuit. The control chip L6599 outputs two-way PWM, through the driver chip UCC27324 and the isolation transformer in the drive circuit, outputs four-way PWM to increase the driving capability to control the power tube of the LLC full-bridge booster circuit; the DSP control chip TMS320F2812 outputs four-way SPWM, The optocoupler isolation in the drive circuit, the Darlington circuit composed of NPN and PNP, and the isolation drive transformer increase the drive capability to control the power tube of the DC/AC inverter circuit.

The sampling circuit realizes the sampling of various electrical parameters, and two sampling circuits are used to collect parameter values: one sampling circuit collects the voltage of the battery, the current of the battery, the DC bus voltage, and the current of the LLC primary side, and adjusts the sampling signal to 0—— The signal between 5VDC is transmitted to the control chip PIC16F877A; another sampling circuit collects grid voltage, grid current, grid frequency, LCL parameters (current of inductor L1, voltage of capacitor C, current of inductor L2), bus voltage, and samples The signal is adjusted into a signal between 0-3.3VDC and transmitted to the DSP control chip TMS320F2812.

The protection circuit realizes the protection of the main circuit unit, including over/under voltage of the battery input voltage, over/under voltage of the output grid voltage, over temperature and over current of the LLC boost circuit, over/under voltage of the DC bus voltage, DC / AC inverter circuit over temperature, over current. The voltage signal after sampling signal conditioning is compared with the reference voltage for calculating the protection point. When a fault occurs, the PWM signal of the drive circuit is turned off, so that the switch tube is always in the off state, achieving the protection function of the device.

Communication circuitry is used for communication with other devices. Communicate with other devices (monitoring devices) through RS485 interface and peripheral circuit configuration or through CAN interface to coordinate work.

The auxiliary power supply unit is used to supply the operating voltage to the control unit. The auxiliary power unit includes an auxiliary power unit 1 and an auxiliary power unit 2. The input of the auxiliary power unit 1 is connected to the output terminal of the storage battery, and the input of the auxiliary power unit 2 is connected to the power grid.

The Human Interface Unit is capable of setting and displaying device parameters. Through three buttons, three indicator lights and digital tubes, the discharge current can be set, the displayed content can be changed, the working status of the device can be checked (operation, fault, protection), and the input voltage/current can be displayed.

The device feeds back the electric energy of the battery to the AC220V power grid through a boost circuit, an inverter circuit and a filter circuit, realizing the recovery of electric energy, replacing the traditional discharge method of heating, greatly reducing energy loss and complying with the national energy saving and emission reduction policy.

Specific embodiments have been given above, but the present invention is not limited to the described embodiments. The basic idea of the present invention lies in the above-mentioned basic scheme. For those of ordinary skill in the art, according to the teaching of the present invention, it does not need to spend creative labor to design various deformation models, formulas, and parameters. Changes, modifications, substitutions and variations to the implementations without departing from the principle and spirit of the present invention still fall within the protection scope of the present invention.

Claims (2)

1. a kind of grid-connected electric discharge device of storage battery activation, which is characterized in that the electric discharge device includes main circuit unit and control Unit, the main circuit unit include sequentially connected LLC booster circuit, inverter circuit and filter circuit, and battery connects institute The input terminal of LLC booster circuit is stated, the output end of the filter circuit connects power grid, and described control unit includes controller and drive Dynamic circuit, controller control connection driving circuit, driving circuit be used for the power tube in LLC booster circuit and inverter circuit into Row driving.

2. the grid-connected electric discharge device of storage battery activation according to claim 1, which is characterized in that described control unit further includes For acquiring the sample circuit of the electrical parameter of the electric discharge device, the protection circuit for being protected to main circuit unit and use In the telecommunication circuit of correspondence with foreign country, the electrical parameter includes at least the electricity of the voltage of battery, the electric current of battery, DC bus Pressure, network voltage and power network current, it is described protection is carried out to main circuit unit to include at least the mistake of battery input voltage/under-voltage Mistake/under-voltage protection of protection and output network voltage.