Method for controlling energy recovery of electric locomotive by adopting control strategy of bidirectional DC-DC (Direct Current-Direct Current) converter

Abstract

The invention relates to a method for controlling energy recovery of an electric locomotive by adopting a control strategy of a bidirectional DC-DC converter, which belongs to the technical field of energy-saving application of mining equipment and is characterized in that according to the actual application occasion of the mining electric locomotive, according to the uphill and downhill states of the electric locomotive, the energy recovery of the mining electric locomotive is controlled; the controller controls the frequency converter to switch the electric state or the power generation state of the driving motor through the communication line, the electric energy state of the driving motor, the electric energy state of the battery pack 1 and the electric energy state of the battery pack 2 are switched, and energy recovery is achieved. By comparing a current instantaneous value acquired by the Hall current sensor with a voltage instantaneous value of the Hall voltage sensor, switching between constant-voltage power supply and constant-current charging is realized by adopting different control methods, so that stable energy recovery of the decomposed battery type mining electric locomotive is realized by adopting a constant-current or constant-voltage control strategy.

Description

Technical Field:

[0001] The present invention belongs to the technical field of energy-saving applications for mining equipment, and more specifically relates to a decomposed battery type energy recovery device and control method for mine locomotives, and more specifically to a control method for energy recovery of mine locomotives using the control strategy of a bidirectional DC-DC converter. Background Art:

[0002] Mine locomotives are the main equipment for mine transportation, with a single running path and often in an up-and-down running state. At present, most domestic battery-powered mine locomotives use resistors, chopper speed regulation, and there is no energy feedback device during the operation of the motor. Generally, mechanical braking or energy consumption braking is used. Therefore, for mine locomotives with a large difference in absolute height between two places, on the one hand, when the locomotive goes uphill, it will consume more electric energy, bringing great challenges to the endurance of the locomotive, increasing the charging times of the locomotive, and seriously affecting the operation efficiency; on the other hand, when the locomotive is running under heavy load downhill for a long time and braking, whether it is mechanical braking or energy consumption braking, it will reduce the service life of the key components of the locomotive.

[0003] To solve the above problems, at present, most use electro-hydraulic braking, bidirectional AC-DC or single-phase AC-DC with a frequency converter structure, and most use a large number of mechanical switches to switch the operating state, inevitably resulting in complex structures of the entire feedback drive device, unclear braking and feedback logic, and low energy recovery efficiency, which are not suitable for the safe operation of mine locomotives.

[0004] The present invention provides a decomposed battery type energy recovery device and implementation method for mine locomotives. By decomposing the battery and using a bidirectional DC-DC converter, only one diode can be used to realize the working switching of two groups of batteries, which better overcomes the shortcomings of the prior art. Summary of the Invention:

[0005] To solve the above problems and overcome the deficiencies of the prior art, the present invention provides a control method for energy recovery of mine locomotives using the control strategy of a bidirectional DC-DC converter, which can effectively solve the problem that the existing locomotive energy recovery cannot be applied due to the complex operating environment of mine locomotives.

[0006] The specific technical solution of the present invention to solve the above technical problems is: a decomposed battery type energy recovery device for mine locomotives, including battery pack 1 and battery pack 2, characterized in that the terminal voltage U1 of battery pack 1 is greater than the terminal voltage U2 of battery pack 2, and the terminal voltage U1 of battery pack 1 meets the requirements of the frequency converter for the DC bus voltage.

[0007] The positive terminal (+) of the battery pack 1 is connected to the anode of the power diode, the cathode of the diode is connected to the positive terminal P of the DC bus of the frequency converter, and is also connected to the C terminal of the bidirectional DC-DC converter. The output terminal of the frequency converter is connected to the drive motor of the battery locomotive. The negative terminal of the battery pack 1 is directly connected to the DC bus N terminal of the frequency converter and is also connected in parallel to the D terminal of the bidirectional DC-DC device.

[0008] Among them, the positive terminal (+) of the output of the battery pack 2 is connected in series with a Hall current sensor and then the positive terminal (+) and the negative terminal (-) are respectively connected to the A and B terminals of the bidirectional DC-DC circuit. A Hall voltage sensor is connected in parallel between A and B. The output signals of the two sensors are respectively connected to the AD sampling terminal 1 and the AD sampling terminal 2 of the controller.

[0009] Furthermore, both the battery pack 1 and the battery pack 2 are provided with battery management system (BMS) devices. The two BMSs establish communication with the controller through two buses CAN_H and CAN_L, and adopt the CAN communication protocol.

[0010] Furthermore, communication is established between the controller and the frequency converter through two communication lines 485+ and 485-.

[0011] The control method of the disassembled battery type mine locomotive energy recovery device adopts the disassembled battery type mine locomotive energy recovery device. According to the actual application scenario of the mine locomotive, when the locomotive is in the uphill or downhill state, the controller controls the frequency converter to switch the drive motor between the electric state and the power generation state through the communication line. At the same time, the controller reads the remaining battery capacity information (SOC) of the BMS of the battery pack 2 through the CAN bus, so as to control the state of the bidirectional DC-DC converter, switch the power states of the drive motor, the battery pack 1 and the battery pack 2, and realize energy recovery.

[0012] The control method of the disassembled battery type mine locomotive energy recovery device specifically includes:

[0013] When the locomotive is in the uphill stage, if the SOC of the battery pack 2 is greater than 20% and less than 100%, then control the bidirectional DC-DC converter to be in the boost state, that is, the energy flows from the AB side to the CD side of the bidirectional DC-DC converter. To ensure that when the battery pack 2 is working, the battery pack 1 is in the natural off state, control the output voltage Ucd of the bidirectional DC-DC converter to be slightly higher than the voltage across the battery pack 1, so that the power diode VR is in the reverse blocking state;

[0014] When the battery locomotive is on the uphill stage, if the SOC of the battery pack 2 is greater than 0 and less than 20%, the bidirectional DC-DC converter is controlled to stop working. Since the output voltage of the bidirectional DC-DC converter is slightly higher than that of the battery pack 1 before it stops working, the energy required for the drive motor naturally switches from the bidirectional DC-DC converter to the battery pack 1, achieving a smooth transition;

[0015] When the battery locomotive is on the downhill stage and the power of the battery pack 2 is greater than 0 and less than 100%, the controller controls the frequency converter to work in the braking power generation state, and at the same time controls the bidirectional DC-DC converter to work in the buck state. According to the different power of the battery pack 2, under the condition that the charging current and charging voltage do not exceed the allowable values, with the goal of maintaining the bus voltage constant, keeping the bus voltage value greater than the terminal voltage of the battery pack 1, the bidirectional DC-DC converter adopts a constant current or constant voltage control strategy according to the remaining power state of the battery pack 2 and the magnitude of the feedback energy, and stores the electric energy generated by the battery locomotive running downhill into the battery pack 2 to achieve the recovery of electric energy; if the power of the electric energy generated by the battery locomotive running downhill is greater than the maximum recovery capacity of the battery pack 2, by controlling the conduction of VT3 and controlling its conduction duty cycle, the excess energy is dynamically consumed through the resistor R2 to maintain the stability of the DC voltage;

[0016] When the battery locomotive is on the downhill stage, if the power in the battery pack 2 reaches 100%, the bidirectional DC-DC converter is controlled to stop working. At the same time, an instruction is sent to the frequency converter through 485+ and 485-, and the motor is still controlled in the power generation state, and the generated electric energy is consumed on the braking resistor inside the frequency converter to achieve energy consumption braking.

[0017] The beneficial effects of the present invention are:

[0018] 1. The present invention creatively sets up an energy recovery device for a split-battery mine locomotive with a bidirectional DC-DC converter circuit, realizing the energy recovery of the split-battery mine locomotive;

[0019] 2. The present invention creatively sets up an energy recovery device for a split-battery mine locomotive with a bidirectional DC-DC converter circuit. According to the actual application scenario of the mine locomotive, when the locomotive is in the uphill or downhill state, the controller controls the frequency converter to switch the driving motor between the electric state and the power generation state through the communication line. At the same time, the controller reads the remaining power information (SOC) of the BMS of the battery pack 2 through the CAN bus, thereby controlling the state of the bidirectional DC-DC converter, switching the electric energy states of the driving motor, the battery pack 1 and the battery pack 2 and realizing energy recovery. Description of the drawings:

[0020] Attached Figure 1 is the circuit diagram of the energy recovery device for the split-battery mine locomotive of the present invention;

[0021] Appendix Figure 2 is the circuit diagram of a bidirectional DC-DC converter; Specific implementation manners:

[0022] In the description of the present invention, specific details are only for fully understanding the embodiments of the present invention. However, those skilled in the art should know that the implementation of the present invention is not limited to these details. Additionally, well-known structures and functions are not described or shown in detail to avoid obscuring the key points of the embodiments of the present invention. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] Specific implementation manners of the present invention:

[0024] For better understanding the present invention, specific embodiments are used for illustration. It should be emphasized that the effects of this embodiment have no substantial differences from various embodiments within the protection scope of the present invention, including their respective reagents and the content ratios of the reagents, and all can achieve the effects described in the present invention and solve the above problems. Other combinations are not elaborated here;

[0025] As an embodiment of the present invention:

[0026] The energy recovery device for a battery-separated mine electric locomotive includes battery pack 1 and battery pack 2. The terminal voltage U1 of battery pack 1 is greater than the terminal voltage U2 of battery pack 2, and the terminal voltage U1 of battery pack 1 meets the requirements of the inverter for the DC bus voltage.

[0027] The positive terminal (+) of battery pack 1 is connected to the anode of a power diode, the cathode of the diode is connected to the positive terminal P of the inverter DC bus and simultaneously to the C terminal of the bidirectional DC-DC converter, and the output terminal of the inverter is connected to the driving motor of the electric locomotive; the negative terminal of battery pack 1 is directly connected to the DC bus N terminal of the inverter and simultaneously connected in parallel to the D terminal of the bidirectional DC-DC device;

[0028] As a creative setting of the present invention, the bidirectional DC-DC converter of the present invention has an original circuit connection structure. Specifically: the A terminal of the bidirectional DC-DC converter is connected to one end of an inductor L, the other end of the inductor L is connected to a resistor R1, and the other end of the resistor R1 is provided with the emitter of a power device VT1, one end of a resistor R2, and the collector of a power device VT2; the collector of VT1 is connected to the C terminal, the emitter of VT2 is simultaneously connected to the B terminal and the D terminal, the other end of the resistor R2 is connected to the collector of a power device VT3, its emitter is connected to the D terminal, a capacitor C1 is connected in parallel between the A terminal and the B terminal, a capacitor C2 is connected in parallel between the C terminal and the D terminal, and the gates of the three power devices are respectively connected to control signal 1, control signal 2, and control signal 3.

[0029] Among them, the positive terminal (+) of the output of the battery pack 2 is connected in series to a Hall current sensor and then the positive and negative terminals (-) are respectively connected to the A and B terminals of the bidirectional DC-DC circuit. A Hall voltage sensor is connected in parallel between A and B. The output signals of the two sensors are respectively connected to the AD sampling terminal 1 and the AD sampling terminal 2 of the controller.

[0030] Furthermore, both the battery pack 1 and the battery pack 2 are equipped with battery management system (BMS) devices. The two BMSs establish communication with the controller through two buses, CAN_H and CAN_L, and adopt the CAN communication protocol.

[0031] As a supplement: Communication is established between the controller and the frequency converter through two communication lines, 485+ and 485-.

[0032] In addition, the present invention also includes a control method for the energy recovery device of the split-battery mine locomotive. The split-battery mine locomotive energy recovery device described above is adopted. The core lies in: According to the actual application scenario of the mine locomotive, when the locomotive is in the uphill or downhill state, the controller controls the frequency converter to switch the driving motor between the electric state and the generating state through the communication line. At the same time, the controller reads the remaining battery capacity information (SOC) of the BMS of the battery pack 2 through the CAN bus, thereby controlling the state of the bidirectional DC-DC converter, switching the power states of the driving motor, the battery pack 1, and the battery pack 2, and realizing energy recovery, thus solving the problem that the existing locomotive energy recovery cannot be applied due to the complex operating environment of the mine locomotive.

[0033] The control method of the energy recovery device of the split-battery mine locomotive is specifically as follows:

[0034] When the locomotive is in the uphill stage, if the SOC of the battery pack 2 is greater than 20% and less than 100%, then control the bidirectional DC-DC converter to be in the boost state, that is, the energy flows from the AB side to the CD side of the bidirectional DC-DC converter. To ensure that when the battery pack 2 is working, the battery pack 1 is in the natural off state, control the output voltage Ucd of the bidirectional DC-DC converter to be slightly higher than the voltage across the battery pack 1, so that the power diode VR is in the reverse blocking state.

[0035] When the locomotive is in the uphill stage, if the SOC of the battery pack 2 is greater than 0 and less than 20%, control the bidirectional DC-DC converter to stop working. Since the output voltage of the bidirectional DC-DC converter is slightly higher than the voltage of the battery pack 1 before it stops working, therefore, the energy required by the driving motor naturally switches from the bidirectional DC-DC converter to be provided by the battery pack 1, realizing a smooth transition.

[0036] When the battery locomotive is in the downhill stage and the power of the battery pack 2 is greater than 0 and less than 100%, the controller controls the frequency converter to work in the braking power generation state, and at the same time controls the bidirectional DC-DC converter to work in the buck state. According to the different power of the battery pack 2, and when the charging current and charging voltage do not exceed the allowable values, with the goal of maintaining the bus voltage constant, keeping the bus voltage value greater than the terminal voltage of the battery pack 1, the bidirectional DC-DC converter adopts a constant current or constant voltage control strategy according to the remaining power state of the battery pack 2 and the magnitude of the feedback energy, and stores the electric energy generated by the battery locomotive running downhill into the battery pack 2 to realize the recovery of electric energy; if the power of the electric energy generated by the battery locomotive going downhill is greater than the maximum recovery capacity of the battery pack 2, by controlling the conduction of VT3 and controlling its conduction duty ratio, the excess energy is dynamically consumed through the resistor R2 to maintain the stability of the DC voltage;

[0037] When the battery locomotive is in the downhill stage, if the power in the battery pack 2 reaches 100%, the controller controls the bidirectional DC-DC converter to stop working. At the same time, an instruction is sent to the frequency converter through 485+ and 485-, and the motor is still controlled in the power generation state, and the generated electric energy is consumed on the braking resistor inside the frequency converter to realize energy consumption braking.

[0038] As a further preferred embodiment of the present invention, in order to realize the utilization according to the actual application occasion of the mine battery locomotive, when the battery locomotive is in the uphill and downhill states, the controller controls the frequency converter to switch the driving motor between the electric state and the power generation state through the communication line, and at the same time can realize the switching between constant voltage power supply and constant current charging. The bidirectional DC-DC converter of the present invention can also adopt a control strategy, that is, according to the characteristics of the load connected to the bidirectional DC-DC converter, by comparing the instantaneous current value collected by the Hall current sensor and the instantaneous voltage value of the Hall voltage sensor, different control methods are adopted to realize the switching between constant voltage power supply and constant current charging; thus, a constant current or constant voltage control strategy is adopted to realize the stable energy recovery of the split battery type mine battery locomotive.

[0039] Specifically: The control strategy adopted by the bidirectional DC-DC converter is:

[0040] When the bidirectional DC-DC converter is in the boost power supply working mode, that is, when the energy flows from the AB side to the CD side, the controller controls VT1 to be in the off state, and by controlling the ratio of the conduction time and the cut-off time of VT2 (duty ratio), the output voltage Ucd of the bidirectional DC-DC converter is maintained at a constant value to realize constant voltage power supply;

[0041] When the bidirectional DC-DC converter is in the step-down charging mode of operation, that is, when the energy flows from the CD side to the AB side, the controller controls VT2 to be in the off state. According to the charging requirements of the BMS of the battery pack 2, by controlling the ratio of the conduction time to the cut-off time (duty cycle) of VT1, the switching between constant voltage or constant current charging of the battery is completed.

[0042] In summary:

[0043] 1. The present invention creatively provides an energy recovery device for a split-battery type mine locomotive with a bidirectional DC-DC converter circuit, realizing the energy recovery of the split-battery type mine locomotive.

[0044] 2. The present invention creatively provides an energy recovery device for a split-battery type mine locomotive with a bidirectional DC-DC converter circuit. According to the actual application scenario of the mine locomotive, when the locomotive is in the uphill or downhill state, the controller controls the frequency converter to switch the driving motor between the electric state and the generating state through the communication line. At the same time, the controller reads the remaining power information (SOC) of the BMS of the battery pack 2 through the CAN bus, thereby controlling the state of the bidirectional DC-DC converter, switching the power states of the driving motor, the battery pack 1, and the battery pack 2, and realizing energy recovery.

[0045] 3. The bidirectional DC-DC converter of the present invention also adopts a control strategy, that is, according to the characteristics of the load connected to the bidirectional DC-DC converter, by comparing the instantaneous current value collected by the Hall current sensor and the instantaneous voltage value of the Hall voltage sensor, different control methods are adopted to realize the switching between constant voltage power supply and constant current charging, and then a constant current or constant voltage control strategy is adopted to realize the energy recovery of the split-battery type mine locomotive.

Claims

1. A control method for energy recovery of a battery locomotive using a control strategy of a bidirectional DC-DC converter, which utilizes a decomposed battery type energy recovery device for a mine locomotive. Characterized in that According to the actual application scenario of the mine locomotive, when the locomotive is in the uphill or downhill state, the controller controls the frequency converter to switch the driving motor between the electric state and the generating state through a communication line. At the same time, the controller reads the remaining battery capacity information SOC of the BMS of battery pack 2 through the CAN bus, thereby controlling the state of the bidirectional DC-DC converter. According to the characteristics of the load connected to the bidirectional DC-DC converter, by comparing the instantaneous current value collected by the Hall current sensor and the instantaneous voltage value of the Hall voltage sensor, different control methods are adopted to achieve the switching between constant voltage power supply and constant current charging, so as to adopt a constant current or constant voltage control strategy to achieve stable energy recovery of the decomposed battery type mine locomotive.

2. The control method for energy recovery of a locomotive using a control strategy of a bidirectional DC-DC converter according to claim 1. Characterized in that: When the locomotive is in the uphill stage, if the SOC of battery pack 2 is greater than 20% and less than 100%, the bidirectional DC-DC converter is controlled to be in the boost state, that is, the energy flows from the AB side to the CD side of the bidirectional DC-DC converter. To ensure that when battery pack 2 is working, battery pack 1 is in the natural off state, the output voltage Ucd of the bidirectional DC-DC converter is controlled to be slightly higher than the voltage across battery pack 1, so that the power diode VR is in the reverse blocking state. When the locomotive is in the uphill stage, if the SOC of battery pack 2 is greater than 0 and less than 20%, the bidirectional DC-DC converter is controlled to stop working. Since the output voltage of the bidirectional DC-DC converter is slightly higher than the voltage of battery pack 1 before it stops working, the energy required by the driving motor naturally switches from the bidirectional DC-DC converter to battery pack 1, achieving a smooth transition. When the locomotive is in the downhill stage and the battery capacity of battery pack 2 is greater than 0 and less than 100%, the controller controls the frequency converter to work in the braking and generating state, and at the same time controls the bidirectional DC-DC converter to work in the buck state. According to the different battery capacities of battery pack 2, under the condition that the charging current and charging voltage do not exceed the allowable values, with the goal of maintaining the bus voltage constant, the bus voltage value is kept greater than the terminal voltage of battery pack 1. The bidirectional DC-DC converter adopts a constant current or constant voltage control strategy according to the remaining battery capacity state of battery pack 2 and the magnitude of the feedback energy, and stores the electric energy generated during the downhill operation of the locomotive into battery pack 2 to achieve the recovery of electric energy. If the power of the electric energy generated by the locomotive going downhill is greater than the maximum recovery capacity of battery pack 2, by controlling the conduction of VT3 and its conduction duty cycle, the excess energy is dynamically dissipated through resistor R2 to maintain the stability of the DC voltage. When the battery locomotive is in the downhill stage, if the battery level in battery pack 2 reaches 100%, the bidirectional DC-DC converter is controlled to stop working. At the same time, an instruction is sent to the frequency converter through 485+ and 485-, and the motor is still controlled in the power generation state. The generated electric energy is consumed on the braking resistor inside the frequency converter to achieve energy consumption braking.

3. The control method for energy recovery of a battery locomotive using the control strategy of a bidirectional DC-DC converter according to claim 2, characterized in that one end of the inductor L is connected to terminal A of the bidirectional DC-DC converter, the other end of the inductor L is connected to resistor R1, and the other end of resistor R1 is provided with the emitter of power device VT1, one end of resistor R2 and the collector of power device VT2; the collector of VT1 is connected to terminal C, the emitter of VT2 is simultaneously connected to terminal B and terminal D, the other end of resistor R2 is connected to the collector of power device VT3, and its emitter is connected to terminal D. Capacitor C1 is connected in parallel between terminal A and terminal B, and capacitor C2 is connected in parallel between terminal C and terminal D. The gates of the three power devices are respectively connected to control signal 1, control signal 2 and control signal 3.

4. The control method for energy recovery of a battery locomotive using the control strategy of a bidirectional DC-DC converter according to any one of claims 1-3, characterized in that: When the bidirectional DC-DC converter is in the boost power supply working mode, that is, when the energy flows from the AB side to the CD side, the controller controls VT1 to be in the off state. By controlling the ratio of the conduction time to the cut-off time of VT2, the output voltage Ucd of the bidirectional DC-DC converter is maintained at a constant value to achieve constant voltage power supply; When the bidirectional DC-DC converter is in the buck charging working mode, that is, when the energy flows from the CD side to the AB side, the controller controls VT2 to be in the off state. According to the charging requirements of the BMS of battery pack 2, by controlling the ratio of the conduction time to the cut-off time of VT1, the switching between constant voltage or constant current charging of the battery is completed.

5. The control method for energy recovery of a battery locomotive using the control strategy of a bidirectional DC-DC converter according to claim 4, characterized in that The disassembled battery type mine battery locomotive energy recovery device includes battery pack 1 and battery pack 2. It is characterized in that the terminal voltage U1 of battery pack 1 is greater than the terminal voltage U2 of battery pack 2, and the terminal voltage U1 of battery pack 1 meets the requirements of the frequency converter for the DC bus voltage. The positive terminal + of battery pack 1 is connected to the anode of the power diode, the cathode of the diode is connected to the positive terminal P of the DC bus of the frequency converter, and is simultaneously connected to terminal C of the bidirectional DC-DC converter. The output terminal of the frequency converter is connected to the drive motor of the battery locomotive; the negative terminal of battery pack 1 is directly connected to the DC bus N terminal of the frequency converter and is simultaneously connected in parallel to terminal D of the bidirectional DC-DC device.

6. The control method for energy recovery of a battery locomotive using the control strategy of a bidirectional DC-DC converter according to claim 5, characterized in that The positive terminal + of the output of the battery pack 2 is connected in series with a Hall current sensor and then the positive and negative terminals - are respectively connected to the A and B terminals of the bidirectional DC-DC circuit. A Hall voltage sensor is connected in parallel between A and B. The output signals of the two sensors are respectively connected to the AD sampling terminal 1 and the AD sampling terminal 2 of the controller.

7. The control method for the energy recovery of the battery locomotive by adopting the control strategy of the bidirectional DC-DC converter according to claim 5, characterized in that both the battery pack 1 and the battery pack 2 are provided with battery management system BMS devices. The two BMSs establish communication with the controller through two buses CAN_H and CAN_L and adopt the CAN communication protocol.

8. The control method for the energy recovery of the battery locomotive by adopting the control strategy of the bidirectional DC-DC converter according to claim 5, characterized in that the controller and the frequency converter establish communication through two communication lines 485+ and 485-.

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