CN106208718A - A kind of bidirectional DC/DC system and method based on state transfer - Google Patents

Abstract

The invention discloses a kind of bidirectional DC/DC system and method based on state transfer; including two-way full-bridge converter, DCDC reversible controller, for duty switching state shift module and cross limit with protection module, described DCDC reversible controller output drive signal is to two-way full-bridge converter；Described state shift module four kinds of signals of input, respectively DCDC reversible controller enables signal, DCDC reversible controller mode altering signal, the inductance zero current indication signal of DCDC reversible controller and crosses the system exception input signal of limit and protection module；Described state shift module output current setting value switching signal and driving anergy signal are to DCDC reversible controller；Described voltage and the current signal crossing limit and protect the module two-way full-bridge converter of input.The present invention is capable of the quick controlled switching of state of power direction.

Description

A bidirectional DCDC system and method based on state transition

technical field

The invention relates to the field of bidirectional DCDC, in particular to a bidirectional DCDC system and method based on state transfer.

Background technique

In recent years, power electronics technology has been paid attention to with the rapid development of power semiconductors. In the case of bidirectional flow of energy that requires step-up and step-down, bidirectional DC-DC converters are the best choice in the DC field.

However, when the traditional bidirectional DCDC fails or changes the power direction, it basically turns off the PWM waveform of the system simply and rudely. Since the bidirectional DCDC has magnetic components, this rough method will make both ends of the magnetic component The voltage rises suddenly, and in severe cases, the switch tube and magnetic components will be damaged.

At present, there are technologies for multi-mode control of bidirectional DCDC, but all of them need to turn off the power tube during the switching process, which fails to solve the above problems.

The paper "Research on Topology and Analysis Theory of High-power Bidirectional DC_DC Converter" proposed a buck-boost switching method for state transfer, but when the bidirectional DCDC is idle, the power switches are all turned off, which fails to solve the above problems.

The paper "Research and Design of Digital Control of Bidirectional DC_DC Converter" proposes a switching method based on delay. In this switching method, accurate switching cannot be performed according to the state of the system, and the above problems have not been solved in fact.

Contents of the invention

In order to overcome the shortcomings and deficiencies of the prior art, the present invention provides a bidirectional DCDC system and method based on state transfer.

The present invention adopts following technical scheme:

A bidirectional DCDC system based on state transfer, including a bidirectional full bridge converter, a DCDC bidirectional controller, a state transfer module for switching working states, and an overlimit and protection module, the DCDC bidirectional controller outputs drive signals to the bidirectional full bridge bridge converter;

The state transfer module inputs four kinds of signals, which are the DCDC bidirectional controller enable signal, the DCDC bidirectional controller mode change signal, the DCDC bidirectional controller's inductance zero current indication signal, and the system abnormality input signal of the overlimit and protection module; The state transfer module outputs the current setting value switching signal and the drive disable signal to the DCDC bidirectional controller;

The overlimit and protection module inputs the voltage and current signals of the bidirectional full-bridge converter.

The DCDC bidirectional controller includes a console, a PWM analog controller and a control loop switcher;

The console includes a DCDC bidirectional controller enabling module, a mode changing module and an inductance zero current indicating module;

The PWM analog controller includes a step-up and a step-down controller, and realizes step-up and step-down switching under the action of the state transfer module;

The control loop switcher includes a voltage loop and a current loop.

The state transfer module includes a delay recovery operation module, an error state module, a system state machine and an output signal logic operation module, the delay recovery operation module and the error state module are connected to the system state machine, and the system state machine is connected to the output logic operation.

The bidirectional full-bridge converter includes a large voltage difference startup protection bidirectional IGBT, a voltage sensor, a current sensor, a buck full-bridge IGBT group and a boost full-bridge IGBT group.

A method for state transfer of a bidirectional DCDC system. The system includes three operating conditions of power direction switching, failure, and start-stop, and includes four operating states of locking, offline, standby, and running. The specific operating state transfer method is as follows:

After the system is turned on, it enters the locked state before starting. If the inductor zero current indication signal is high level, it enters the offline state; if the inductor zero current indication signal is high level and whether the abnormal signal is low level, it enters the standby state; otherwise does not transfer state;

After entering the standby state, if the DCDC bidirectional controller enable signal is high level, and the mode change signal is high level and whether the abnormal signal is low level, it will enter the running state, otherwise it will remain in the standby state;

After entering the running state, judge whether the enable signal of the DCDC bidirectional controller is low level, whether the mode change signal of the DCDC bidirectional controller is low level, and whether the abnormal signal of the overlimit and protection module is high level. If there is a condition If it is established, it will enter the offline state, otherwise it will remain in the running state;

After entering the off-line state, the state switching module outputs the current setting value switching signal to switch the current loop reference to 0 reference. At this time, the voltage loop of the system is cut off, and the system works in the current single-loop mode with the current reference being 0. At this time, if the inductance zero current indicator signal is high level, it will enter the standby state, otherwise the operation delay will resume the operation module, and then judge the DCDC bidirectional controller enable signal, DCDC bidirectional controller mode change signal and over-limit and protection module after 100us Abnormal signal, if the enable signal of the DCDC bidirectional controller is high level, and the mode change signal is high level and the abnormal signal is low level, then switch the signal according to the current system state output current setting value, and then quickly enter the running state.

The abnormal signals include overvoltage abnormality, overcurrent abnormality and working mode abnormality.

Beneficial effects of the present invention:

(1) Under the three system working conditions of power direction switching, failure and start-stop, the system can judge according to the information monitored by the state transfer module, and can respond quickly under the action of the PWM analog controller;

(2) When the system has a working condition, the current can be given by setting, and according to the system state transition, the output energy of the system is greater than the input energy, and the effective management of energy can be realized;

(3) After the energy stored in the magnetic components in the system is exhausted, the system is locked when the fault condition of the system still cannot be recovered to ensure the safety of the system. After the system returns to normal, start it manually to ensure the reliability of the system;

(4) All signals used for judgment are logic signals, which have strong anti-interference, small transmission delay, and high reliability. It is easy to realize multi-thread control by programmable hardware system, and further improve reliability.

(5) Realize fast switching of power direction when there is no abnormality.

(6) The design of the DCDC bidirectional converter greatly simplifies and improves the rapidity and reliability of control, reduces the cost of equipment, and, without the control of an external state transfer module, the system is always in a locked state, ensuring system security .

Description of drawings

Fig. 1 is a system structure diagram of the present invention;

Fig. 2 is a module composition and connection diagram of the present invention;

Fig. 3 is the main analog circuit diagram of overlimit and protection module of the present invention;

Fig. 4 is the composition structural diagram of the state transfer module of the present invention;

Fig. 5 is each module connection diagram in the state transfer module of the present invention;

Fig. 6 is a simplified diagram of the system state machine in the state transition module of the present invention;

Fig. 7 is the system control block diagram of off-line state of the present invention;

FIG. 8( a ) and FIG. 8( b ) are experimental waveform diagrams of switching between two power directions according to the present invention.

detailed description

The present invention will be described in further detail below in conjunction with the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example

As shown in Figure 1 and Figure 2 and Figure 3, a bidirectional DCDC system based on state transfer includes a bidirectional full-bridge converter, a DCDC bidirectional controller, a state transfer module, and an overlimit and protection module, the state transfer module input The four signals are the system abnormal input signal from the overlimit and protection module, the enable signal from the DCDC bidirectional controller, the mode change signal and the inductor zero current indication signal, and the state transfer module outputs the current setting value switching signal and drive disable signal to DCDC bidirectional controller.

The overlimit and protection module inputs the voltage and current signals of the bidirectional full-bridge converter.

The DCDC bidirectional controller outputs driving signals to the bidirectional full bridge converter.

The state transfer module is responsible for the state switching of the system, including all judgments and executions from steady state to transient state and then to steady state, realizing the control of the entire control system by one state transfer module, and realizing the control of all key signals of the system Judgment, reasonable modification of control reference and control output, to ensure that the system can still respond quickly and reliably under the three working conditions of power direction switching, failure and start-stop.

The DCDC bidirectional controller includes a console, a PWM analog controller and a control loop switcher, wherein the console includes a DCDC bidirectional controller enabling module, a mode changing module and an inductance zero current indicating module;

The PWM analog controller includes a step-up and a step-down controller, and realizes step-up and step-down switching under the action of the state transfer module;

The control loop switcher includes a voltage loop and a current loop.

Such a design method enables the bidirectional converter to be designed in one direction, and finally the state transfer module realizes the state transfer and the switching of the power direction, and finally realizes a bidirectional DCDC system. Moreover, the traditional PWM analog controller is pure hardware control, with low complexity, low cost, high reliability and good control effect, which is the basis for fast switching power direction of bidirectional DCDC system.

The bidirectional full-bridge converter includes a large voltage difference startup protection bidirectional IGBT, a voltage sensor, a current sensor, a buck full-bridge IGBT group and a boost full-bridge IGBT group, which improves the application range of the system.

As shown in Fig. 4, Fig. 5 and Fig. 6, the state transfer module includes a delay recovery operation module, an error state module, a system state machine and an output signal logic operation module.

In order to ensure reliable transfer, the present invention adds a delay recovery operation module, an error state module and an output signal logic operation module on the basis of the original system state machine, to assist the system state machine in transferring state and protecting the DCDC bidirectional converter. At the same time, the abnormal input signal of the state transfer module includes an abnormal overvoltage, an abnormal overcurrent and an abnormal working mode.

At the same time, the topology of the main circuit is modified by adding a large voltage drop starting protection bidirectional IGBT to realize shutdown when the inductor current is over-limited when the large voltage drop boost is started, cut off the boost energy source, and wait for the inductor current to return to the normal current value below 30A Switch on the bidirectional IGBT again to continue to provide energy for the subsequent stage. If there is no overcurrent signal, the bidirectional IGBT is always turned on.

As shown in Figure 7, the present invention includes three working conditions, namely system failure, power direction switching and shutdown. In order to realize the system state transfer of these three states, the states include locking, standby, running and offline states. The state transition of the four states depends on the zero current indication of the inductor, the enable signal of the DCDC bidirectional controller, the mode change signal of the DCDC bidirectional controller, and the abnormal signal of the overlimit and protection module. In such a design scheme, all signals are level signals, with strong anti-interference and small transmission delay, which is beneficial to realize multi-threaded fast judgment by using programmable hardware circuits. At the same time, relying on the monitoring of the above four system signals, comprehensively considering the three working conditions of system failure, power direction switching or system start and stop, the system has perfect functions.

Since the bidirectional DCDC system includes boost and buck modes, when the power direction changes or a fault occurs, if the PWM signal of one side of the IGBT group is immediately blocked, and then the PWM signal of the other side is turned on, the current in the system will not be normal. commutation, thereby blowing up the IGBT group and damaging the system.

The specific transfer method is:

(1) The system enters the locked state after starting up and before starting. If the inductor zero current indication signal is high level, it will enter the offline state; if the inductor zero current indication signal is high level and whether the abnormal signal is low level, it will enter the standby state state; otherwise do not transfer state;

(2) After entering the standby state, if the DCDC bidirectional controller enable signal is high level, and the mode change signal is high level and whether the abnormal signal is low level, it will enter the running state, otherwise it will remain in the standby state;

(3) After entering the running state, judge whether the enable signal of the DCDC bidirectional controller is low level, whether the mode change signal of the DCDC bidirectional controller is low level, and whether the abnormal signal of the overlimit and protection module is high level, if If a condition is met, it will enter the offline state, otherwise it will remain in the running state;

(4) After entering the offline state, the state switching module outputs the current setting value switching signal to switch the setting of the current loop to 0. At this time, the voltage loop of the system is also cut off, and it works in the current single with the current setting of 0. Ring mode, at this time, if the inductance zero current indicator signal is high level, it will enter the standby state, otherwise the operation delay will resume the operation module, and then judge the DCDC bidirectional controller enable signal, DCDC bidirectional controller mode change signal and over-limit and To protect the abnormal signal of the module, if the enable signal of the DCDC bidirectional controller is high level, and the mode change signal is high level and the abnormal signal is low level, then output the current setting value switching signal according to the current system state, and then quickly enter Operating status.

The key of the bidirectional DCDC system based on state transfer is the offline mode. In the offline mode, the system does not lock the PWM output of the system, but outputs the switching signal of the current setting value through the state transfer module to output the current setting value shown in the thick black box to the The fixed switching switch is switched to the 0 reference of the current loop, so as to realize the protection operation in the offline mode. On the one hand, because the current loop is set to 0, the system quickly drops to 0 current output according to the DCDC control algorithm, preventing the energy from being further transmitted into the system and causing System failure, on the other hand, does not directly cut off the PWM drive or directly block the PWM drive as in the prior art, but keeps the PWM drive working in the normal mode until the inductor current of the system drops to 0 before blocking the PWM drive. The energy inside the system provides a reasonable release path.

As shown in Fig. 8(a) and Fig. 8(b), when the power direction switching between the over-limit and the protection module is normal, the system enters the offline mode, and the fast control system makes the inductor current drop to 0 quickly. At this time Enter the standby mode and switch the buck-boost drive signal to realize zero-current power direction switching, and switch the current loop given switch at the same time to enter the running state to realize the rapid start of the new power direction. Experiments have proved that this fast switching method can make the current drop to 0 within 2 control cycles in the current mode, and can make the current rise to a specified value within 2 control cycles. The time delay of staying in the standby state can be customized by the system, here it is set to 100us, which realizes fast and controllable switching of the power direction.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the embodiment, and any other changes, modifications, substitutions and combinations made without departing from the spirit and principle of the present invention , simplification, all should be equivalent replacement methods, and are all included in the protection scope of the present invention.

Claims (6)

1. a bidirectional DC/DC system based on state transfer, it is characterised in that include the two-way control of two-way full-bridge converter, DCDC Device processed, for duty switching state shift module and cross limit with protection module, described DCDC reversible controller output drive Dynamic signal is to two-way full-bridge converter；

Described state shift module four kinds of signals of input, respectively DCDC reversible controller enables signal, DCDC reversible controller Mode altering signal, the inductance zero current indication signal of DCDC reversible controller and cross limit with protection module system exception input Signal；Described state shift module output current setting value switching signal and driving anergy signal are to DCDC reversible controller；

Described voltage and the current signal crossing limit and protect the module two-way full-bridge converter of input.

Bidirectional DC/DC system the most according to claim 1, it is characterised in that described DCDC reversible controller includes operation Platform, PWM analog controller and control ring cutting parallel operation；

Described operating board includes that DCDC reversible controller enables module, mode altering module and inductance zero current indicating module；

Described PWM analog controller includes boosting and buck controller, realizes voltage step-up/step-down under the effect of state shift module Change；

Described control ring cutting parallel operation includes Voltage loop and electric current loop.

Bidirectional DC/DC system the most according to claim 1, it is characterised in that described state shift module includes delayed recovery Run module, error condition module, system mode machine and output signal logical operation module, described delayed recovery run module and Error condition module is connected with system mode machine, and system mode machine is connected with output logical operations.

Bidirectional DC/DC system the most according to claim 1, it is characterised in that described two-way full-bridge converter includes big pressure reduction The two-way IGBT of starting protection, voltage sensor, current sensor, blood pressure lowering full-bridge IGBT group and boosting full-bridge IGBT group.

5. according to the state transition method of the bidirectional DC/DC system described in any one of claim 1-4, it is characterised in that system bag Include power direction switching, fault and three kinds of operating modes of start and stop, and include locking, off-line, standby and operation totally four kinds of duties, tool Body running state transition method is as follows:

Start after system boot and advance into lock-out state, if inductance zero current indication signal is high level, then enter off-line state； If inductance zero current indication signal is high level and whether abnormal signal is low level, then enter holding state；Do not shift State；

Enter after holding state, if it is high level that DCDC reversible controller enables signal, and mode altering signal be high level and Whether abnormal signal is low level, then enter running status, otherwise keep holding state；

After entering running status, it is judged that DCDC reversible controller enables whether signal is low level, DCDC reversible controller mould Whether formula change signal is low level and crosses limit with whether the abnormal signal protecting module is high level, if there being a condition to become Vertical, then enter off-line state, otherwise remain on state；

After entering off-line state, state handover module output current setting value switching signal is switched to 0 the given of electric current loop Given, at this moment the Voltage loop of system is cut, and system is operated in the electric current monocycle pattern that given value of current is 0, if now inductance zero Current indicating signal is that high level then enters holding state, otherwise runs delayed recovery and runs module, judges after 100us again DCDC reversible controller enables signal, DCDC reversible controller mode altering signal and crosses the abnormal signal of limit and protection module, If it is high level that DCDC reversible controller enables signal, and mode altering signal is high level and abnormal signal is low level, then Export current setting value switching signal according to current system mode, then rapidly enter running status.

State transition method the most according to claim 5, it is characterised in that described abnormal signal includes overvoltage exception, mistake Throat floater and mode of operation are abnormal.