CN107176565A - A kind of fork truck energy saver and energy-saving control method - Google Patents

Abstract

The invention provides an energy-saving device for forklifts, which includes a plurality of functional modules that can individually realize their functions, and the functional modules are all connected to the output terminals of the control chip, and the functional modules are connected in parallel to the energy-saving control circuit, and the energy-saving control circuit includes supercapacitors, storage batteries / battery pack, double-acting AC motor and bidirectional inverter, the output end of the battery/battery pack is connected to the first voltage sensor, the output end of the supercapacitor is connected to the second voltage sensor, and the output end of the functional module passes through the bidirectional inverter Connected to a double acting AC motor with the output of the battery/battery pack connected to the input of the super capacitor. The present invention replaces the battery with a supercapacitor to provide the instantaneous high-power current of the electric forklift during lifting start, lifting acceleration, and acceleration start, avoiding permanent irreparable damage to the battery caused by the instantaneous high-power output of the battery, thereby prolonging the life of the electric forklift. the service life of the battery.

Description

Energy-saving device and energy-saving control method for forklift

technical field

The invention relates to the technical field of forklift control, in particular to an energy-saving device for a forklift and a use method thereof.

Background technique

In recent years, people have higher and higher requirements for energy saving and environmental protection. Electric forklifts are more and more recognized and welcomed by users because of their low noise, zero emissions, and independence from crude oil. They have the potential to become mainstream forklifts in the future, but the current typical electric forklifts Shut down due to the short continuous working time of the battery, and the cycle life of the battery is lower than the normal life due to the influence of the working conditions of the forklift. At the moment when the electric forklift starts to lift a large mass object, the battery instantly outputs a high-power current, causing permanent irreparable damage to the battery itself, which greatly reduces the service life of the battery. Frequent replacement of batteries not only increases the cost, but also pollutes the environment to a certain extent.

At present, batteries such as lead-acid batteries and lithium batteries cannot provide high enough specific energy and specific power at the same time. It is difficult to meet the use requirements of electric forklifts in terms of acceleration lifting, acceleration start, climbing ability and potential energy, braking energy recovery, etc., which seriously restricts the performance of electric forklifts.

The capacity of various supercapacitors introduced in recent years can reach thousands of farads, and some devices and places have used supercapacitors as power sources. However, the storage capacity is extremely small, and the specific energy is extremely low, which generally cannot meet the long-term operation.

At present, for forklift potential energy recovery and battery protection, the existing technologies are as follows:

Taking the Chinese patent CN201310014646.0 as an example, the patent protects the battery during the charging phase of the battery. This is also a widely used battery protection method at present, but it does not effectively protect the battery when the battery is working.

Take Chinese rights CN200910179744.3 and Chinese patent CN201410153416.7 as examples, the patent directly cuts off the working circuit to protect the battery when the battery is damaged or is about to be damaged, causing the equipment to crash.

Taking Chinese patent CN201110132119.0 as an example, the patent uses an accumulator to recover potential energy. Such patents store the hydraulic oil in the accumulator and use it in the next cycle. The structure is complex, the energy utilization rate is low, and there are potential risks. The replaceability is small, and most mechanical equipment cannot use this kind of equipment.

Contents of the invention

The first technical problem to be solved by the present invention is to provide an energy-saving device for a forklift, which can prolong the endurance of the forklift and prolong the service life of the storage battery.

The technical solution adopted by the present invention to solve the above-mentioned technical problems is: an energy-saving device for forklifts, including a plurality of functional modules that can independently realize their functions, and the functional modules are all connected to the output terminals of the control chip, and receive the information from the control chip. The control signal sent out realizes the corresponding function. The functional modules are connected in parallel on the energy-saving control circuit. The output end of the group is connected with a first voltage sensor, and the output end of the supercapacitor is connected with a second voltage sensor, which are respectively used for real-time monitoring of the output voltages of the battery/battery group and the supercapacitor, and the function modules The output end is connected to the double-acting AC motor through a bidirectional inverter, and the output end of the battery/battery pack is connected to the input end of the supercapacitor.

While adopting the above-mentioned technical solution, the present invention can also adopt or adopt the following further technical solutions in combination:

The double-acting AC motor is an engine when it rotates forward, and a generator when it rotates reversely.

A protective resistor is connected in series at the output end of the battery/battery pack; an inductor is connected in series at the output end of the supercapacitor.

The functional modules include a battery independent power supply module, a high-power current module, a battery power supply module, and an energy recovery module. The battery independent power supply module includes a first IGBT for receiving corresponding control signals from the control chip. A first freewheeling diode is connected in parallel, the high-power current module includes a second IGBT for receiving corresponding control signals from the control chip, a second freewheeling diode is connected in parallel on the second IGBT, and the battery power supply module includes a A third freewheeling diode is connected in parallel with the third IGBT receiving the corresponding control signal from the control chip, and the energy recovery module includes a fourth IGBT for receiving the corresponding control signal from the control chip. A fourth freewheeling diode is connected in parallel on the four IGBTs.

The two input terminals of the control chip are respectively connected to the first voltage sensor and the second voltage sensor for receiving the real-time voltage information of the storage battery/battery pack and the supercapacitor, and the four signal output terminals of the control chip are respectively driven by IGBT The circuit is then connected to the battery independent power supply module, the high-power current module, the battery power supply module and the energy recovery module.

Another technical problem to be solved by the present invention is to provide an energy-saving control method for forklifts, that is, an operation method for the above-mentioned energy-saving device for forklifts. The method includes the following four working states:

1) The battery/battery pack is powered separately: when the electric forklift is lifted at a constant speed or is driving, when the driving current required by the motor is equal to or less than the rated operating current or the SOC of the supercapacitor is lower than 50%, the battery/battery pack alone will power the electric forklift powered by;

2) Supercapacitor power supply: When the electric forklift is lifted, lifted, accelerated, and the SOC of the supercapacitor is higher than 50%, the supercapacitor provides the electric forklift with an instantaneous high-power current at the beginning of operation. The instantaneous high-power current can be high at 200A;

3) Battery/battery pack charging: When the SOC of the super capacitor is lower than 50%, the battery/battery pack can charge the super capacitor when the forklift is running or stopped;

4) Energy recovery: when the electric forklift falls back, the double-acting motor reverses, and the circuit is charged through the bidirectional inverter, first charging the super capacitor, and then charging the battery/battery pack after the super capacitor is fully charged.

Further, the four working states are cross-controlled by the first signal, the second signal, the third signal and the fourth signal, and the initial pulses of the first signal, the second signal, the third signal and the fourth signal are all generated by the control chip The width modulation signal is obtained through the IGBT drive circuit, and the control chip adjusts and outputs the control signal in real time according to the real-time monitoring data of the first voltage sensor and the second voltage sensor and the operation input signal of the driver of the electric forklift.

Further, when in the first working state, the battery/battery pack supplies power alone, the third signal controls the on-off of the third IGBT, and the first IGBT, the third IGBT, and the fourth IGBT are in an off state.

When in the 2) working state, the second signal and the third signal respectively control the on-off of the second IGBT and the third IGBT, and both the first IGBT and the fourth IGBT are in the off state; when the second signal controls the second IGBT When it is turned on, the supercapacitor stores energy in the inductor, at this time the third signal controls the third IGBT to turn off; when the second signal controls the second IGBT to turn off, the third signal controls the third IGBT to turn on, and the energy stored in the inductor Output high-power current to supply power to double-acting AC motors.

When in the 3) working state, the first signal controls the on-off of the first IGBT, and the second IGBT, the third IGBT and the fourth IGBT are all turned off. At this time, the first IGBT, the inductor and the second freewheeling diode constitute A BUCK step-down circuit, the battery/battery pack charges the supercapacitor.

When in the 4th) working state, the fourth signal and the first signal control the on-off of the fourth IGBT and the first IGBT, and the third IGBT and the second IGBT are in the off state. The AC motor is reversed to become a generator, and the fourth signal and the first signal are used to adjust the on-off of the fourth IGBT and the first IGBT to charge the supercapacitor.

The beneficial effects of the present invention are: 1. The present invention provides the instantaneous high-power current of the electric forklift during lifting start, lifting acceleration, and acceleration start by replacing the storage battery with a super capacitor, thereby avoiding the permanent damage to the storage battery caused by the instantaneous high-power output of the storage battery. irreparable damage, thereby prolonging the service life of the battery; 2. The present invention can recover the gravitational potential energy and braking energy of the forklift generated when the fork is lowered, prolonging the endurance of the forklift and saving energy; 3. . The invention reduces the power burden of the pump motor, lowers the oil temperature and improves the system efficiency by designing the IGBT drive circuit and the control circuit of the control chip.

Description of drawings

Fig. 1 is a design schematic diagram of the energy-saving device for forklifts of the present invention.

2 is a schematic diagram of the IGBT drive circuit of the present invention, in which A1 is a capacitor, A2 is a resistor, A3 is a triode, A4 is a storage battery, and A5 is an optocoupler chip A3120.

FIG. 3 is a schematic diagram of the output current of the BOOST circuit when the duty ratio of the second signal is 0.66.

detailed description

Below in conjunction with embodiment, technical scheme of the present invention is set forth in more detail, and the implementation of the present invention is not limited to following embodiment, should be understood that, any modification or change on the form that the present invention is made should be within the scope of the present invention. within the scope of protection.

Fig. 1 is the design schematic diagram of the energy-saving device for forklift of the present invention, wherein the voltage sensor monitors the voltage of battery 1 and supercapacitor 11 in real time, and feeds back to the control chip 17, and the control chip 17 combines the above-mentioned feedback information according to the working state of the electric forklift The duty cycle of the first signal to the fourth signal is adjusted in real time, wherein the first signal to the fourth signal are all pulse width modulation signals.

Under the condition that the supercapacitor 11 provides the instantaneous high-power current of the forklift during lifting start, lifting acceleration, and acceleration start, the output circuit of the supercapacitor 11 is composed of a non-isolated BOOST boost circuit and a second signal controlled by the second signal. The IGBT4 is composed of a freewheeling diode 8, a bidirectional inverter 16 and a double-acting AC motor 13. The non-isolated BOOST booster circuit is composed of an inductor 12, a first freewheeling diode 7 and a second IGBT4 controlled by a second signal, as shown in the figure 1.

Fig. 2 is a schematic diagram of the IGBT drive circuit of the present invention, which ensures that the drive signal has a drive voltage of 18V and a maximum drive current of 2A to drive the IGBT, and insulates the primary circuit from the ELV circuit through photoelectric coupling. In addition, the zero point drift phenomenon can be effectively prevented. occur. The IGBT driving circuit is the main functional element of each functional module, which can realize the conditioning and amplitude modulation of the output signal in the control chip 17 to meet the requirements of driving the IGBT.

The second signal and the third signal are generated by the control chip 17 after the initial pulse width modulation signal is passed through the IGBT drive circuit (as shown in Figure 2), and the control chip 17 adjusts the voltage in real time through the real-time monitoring of the first voltage sensor 14 and the second voltage sensor 15 The duty cycle of the second signal and the third signal is used to match the output voltage of the supercapacitor and the battery voltage.

FIG. 3 is a schematic diagram of the output current of the BOOST circuit when the duty cycle of the second signal is 0.66. When the second signal is at Ton (rising edge trigger), the third signal is at Toff (falling edge trigger), the second IGBT4 is turned on, the third IGBT5 is turned off, the supercapacitor 11 charges the inductor 12, the inductor 12 stores energy, and the inductor The amount of current increase (when the inductance coil is not saturated) is:

Among them: D is the duty cycle of the signal, T is the switching period, L is the electric quantity of the inductor, and V _in is the input voltage of the inductor.

When the second signal is at Toff, the third signal is at Ton, the second IGBT4 is turned off, the third IGBT5 is turned on, the inductance 12 is discharged, and the energy of the inductance 12 is transferred to the load through the first freewheeling diode 7, when the inductance 12 The current decreases continuously, and the voltage drop of the first freewheeling diode 7 is ignored, then the current changes as:

Among them: Vo is the inductor output voltage.

And when the third IGBT5 is turned on and the second IGBT4 is turned off, the freewheeling diode 10 performs freewheeling.

When the inductor current is in continuous mode, under steady state conditions, the increase in the current on the inductor 12 is equal to the decrease in its current, that is So sort it out:

Because the duty cycle is 0-1, the output voltage of the BOOST circuit must be greater than the output voltage of the supercapacitor. Adjusting the duty cycle of the second signal can make the output voltage of the BOOST circuit match the output voltage of the battery 1, and because the supercapacitor The discharge characteristics of the capacitor 11, when the energy storage of the super capacitor 11 is sufficient (SOC is not less than 50%), the output current after the BOOST booster circuit can fully meet the requirements of the forklift when it is lifted, accelerated, and accelerated. The instantaneous high-power current of up to 200A is required. The instantaneous high-power current refers to the high-power starting current of up to 200A required for the moment when the electric forklift starts lifting, lifting acceleration, and acceleration starting.

When the power of the supercapacitor 11 is too low and the SOC is less than 50%, the supercapacitor 11 is charged from the storage battery 1, and the current flows in sequence: the storage battery 1, the protection resistor 2, the first IGBT3 controlled by the first signal, and the third freewheeling Diode 9, inductor 12 and supercapacitor 11.

In order to prevent damage to the battery due to excessive charging current, the control chip 17 controls the on-off of the first IGBT3, and the inductance 12 plays a role of stabilizing the current to ensure a stable charging current throughout the charging process.

During energy recovery, the supercapacitor 11 is preferentially charged, followed by the storage battery 1. During charging, the order of electric energy flow is: double-acting AC motor 13, bidirectional inverter 16, fourth IGBT6, third freewheeling diode 9, The first IGBT 3 , the second freewheeling diode 8 , the inductor 12 , the supercapacitor 11 , the protection resistor 2 and the storage battery 1 .

When the double-acting AC motor 13 reverses to become a generator, the inductance coil in the motor, the fourth IGBT6 and the third freewheeling diode 9 form a BOOST boost circuit, the principle is the same as above. Under the control of the fourth signal and the first signal, the on-off conditions of the fourth IGBT6 and the first IGBT3 and the protection resistor 2 and the inductance 12 are adjusted to ensure maximum charging efficiency and protect the supercapacitor 11 and the battery 1 .

The operating method of the energy-saving device for forklifts of the present invention can be divided into four working states, specifically as follows:

1) The battery 1 supplies power alone. When the electric forklift is lifting at a constant speed or driving, when the driving current required by the motor is less than the rated current or the SOC of the supercapacitor 11 is lower than 50%, the battery 1 alone supplies power; at this time, the third signal controls the on-off of the third IGBT5, The first IGBT3, the second IGBT4 and the fourth IGBT6 are all in an off state. The current at the moment when the third IGBT5 is turned off is freewheeling through the fourth freewheeling diode 10 to maintain a stable current before the next turn-on moment.

2) The supercapacitor 11 provides the high-power current for the forklift during lifting start, lifting acceleration, and acceleration start. At this time, the second signal and the third signal respectively control the on-off of the second IGBT4 and the third IGBT5, and both the first IGBT3 and the fourth IGBT6 are in the off state; when the second signal controls the second IGBT4 to be turned on, the supercapacitor 11 stores energy in the inductor 12, at this time the third signal controls the third IGBT5 to turn off; when the second signal controls the second IGBT4 to turn off, the third signal controls the third IGBT5 to turn on, and the energy stored in the inductor 12 can output up to 200A The high power current supplies power to the double-acting AC motor 13.

3) When the power of the supercapacitor 11 is too low, the battery 1 charges the supercapacitor 11 . At this time, the first signal controls the on-off of the first IGBT3, and the second IGBT4, the third IGBT5 and the fourth IGBT6 are all turned off. In this case, the first IGBT3, the second freewheeling diode 8 and the inductor 12 form a The BUCK step-down circuit prevents the instantaneous charging current from being too large and reduces the charging voltage, so that the storage battery 1 can charge the supercapacitor 11 smoothly.

4) During energy recovery, the supercapacitor 11 is preferentially charged, and the storage battery 1 is secondly charged. At this time, the fourth signal and the first signal control the on-off of the fourth IGBT6 and the first IGBT3, the third IGBT5 and the second IGBT4 are in the off state, and the double-acting AC motor 13 reverses when the goods of the electric forklift are descending Become a generator, adjust the opening and closing of the fourth IGBT6 and the first IGBT3 to charge the supercapacitor 11 through the fourth signal and the first signal.

The first signal, the second signal, the third signal and the fourth signal are all generated by the control chip 17. The initial modulation pulse width modulation signal is obtained after conditioning and amplification of the IGBT drive circuit as shown in Figure 2. The first signal, the second signal, the second signal Both the three signals and the fourth signal are controlled by the control chip, and the control chip 17 adjusts the duty cycle of the output signal in real time to control the working state of the whole device after receiving the real-time monitoring data from the first voltage sensor 14 and the second voltage sensor 15.

Claims (10)

1. A kind of energy-saving device for forklift, it is characterized in that: comprise a plurality of function modules that can realize its function independently, described function module is all connected to the output terminal of control chip, and accepts the control signal that control chip sends to realize corresponding function, the functional modules are connected in parallel to the energy-saving control circuit, and the energy-saving control circuit includes a supercapacitor (11), a storage battery/battery pack (1), a double-acting AC motor (13) and a bidirectional inverter (16), The output end of the battery/battery pack (1) is connected to a first voltage sensor (14), and the output end of the supercapacitor (11) is connected to a second voltage sensor (15), which are respectively used for real-time monitoring of the battery / the output voltage of the battery pack (1) and the supercapacitor (11), the output terminal of the functional module is connected to the double-acting AC motor (13) through the bidirectional inverter (16), and the battery/battery pack ( The output end of 1) is connected to the input end of the supercapacitor (11). 2 . The energy-saving device for forklifts according to claim 1 , characterized in that: the double-acting AC motor ( 13 ) is an engine when rotating forward, and a generator when rotating reversely. 3 . 3. An energy-saving device for forklifts according to claim 1, wherein the functional modules include a battery independent power supply module, a high-power current module, a battery power supply module and an energy recovery module, and the battery independent power supply module includes The first IGBT (3) used to receive the corresponding control signal of the control chip, the first freewheeling diode (7) is connected in parallel with the first IGBT (3), and the high-power current module includes a The second IGBT (4) corresponding to the control signal, the second freewheeling diode (8) is connected in parallel to the second IGBT (4), and the battery and supercapacitor power supply module includes a power supply for receiving the corresponding control signal of the control chip a third IGBT (5), the third IGBT (5) is connected in parallel with a third freewheeling diode (9), and the energy recovery module includes a fourth IGBT (6) for receiving a corresponding control signal from the control chip, A fourth freewheeling diode (10) is connected in parallel with the fourth IGBT (6). 4. The energy-saving device for forklifts according to claim 3, characterized in that: the two input terminals of the control chip are respectively connected to the first voltage sensor (14) and the second voltage sensor (15) for receiving The real-time voltage information of the battery/battery pack and supercapacitor, the four signal output terminals of the control chip are respectively connected to the battery independent power supply module, high-power current module, battery power supply module and energy recovery module through the IGBT drive circuit. 5. An energy-saving control method for forklifts, characterized in that the method applies the energy-saving device for forklifts according to any one of claims 1-4, and includes the following four working states: 1) Battery/battery pack (1) alone power supply: When the electric forklift is lifting at a constant speed or driving, when the driving current required by the motor is equal to or less than the rated operating current or the SOC of the super capacitor (11) is lower than 50%, the battery/battery Group (1) alone supplies power to electric forklifts; 2) Supercapacitor (11) power supply: when the electric forklift is lifted, lifted, accelerated, and the SOC of the supercapacitor (11) is greater than 50%, the supercapacitor (11) provides the electric forklift with an instantaneous high-power current of up to 200A ; 3) Battery/battery pack (1) charging: when the SOC of the super capacitor (11) is lower than 50%, the battery/battery pack (1) can charge the super capacitor (11) when the forklift is running or stopped; 4) Energy recovery: when the electric forklift falls back, the double-acting AC motor reverses and charges the circuit through the bidirectional inverter, first charging the super capacitor (11), and then charging the battery/battery pack ( 1) Charging. 6. An energy-saving control method for forklifts according to claim 5, characterized in that: the four working states are cross-controlled by the first signal, the second signal, the third signal and the fourth signal, the first signal, The second signal, the third signal and the fourth signal are all obtained by the control chip (17) after the initial pulse width modulation signal passes through the IGBT drive circuit. The control chip (17) is based on the first voltage sensor (14) and the second The real-time monitoring data of the voltage sensor (15) and the operation input signal of the driver of the electric forklift are adjusted in real time to output the above-mentioned control signal. 7. An energy-saving control method for forklifts according to claim 7, characterized in that: when in the 1st) working state, the battery/battery pack (1) supplies power alone, and the third signal controls the third IGBT (5) On and off, the first IGBT (3), the second IGBT (4), and the fourth IGBT (6) are in the off state. 8. An energy-saving control method for forklifts according to claim 7, characterized in that: when in the second) working state, the second signal and the third signal respectively control the second IGBT (4) and the third IGBT ( 5) on and off, the first IGBT (3) and the fourth IGBT (6) are both in the off state; when the second signal controls the second IGBT (4) to be turned on, the supercapacitor (11) supplies the inductor (12) At this time, the third signal controls the third IGBT (5) to turn off; when the second signal controls the second IGBT (4) to turn off, the third signal controls the third IGBT (5) to turn on, stored in the inductor ( 12) The energy output high-power current supplies power to the double-acting AC motor (13). 9. The energy-saving control method for forklifts according to claim 7, characterized in that: when in the 3rd) working state, the first signal controls the on-off of the first IGBT (3), and the second IGBT (4) , the third IGBT (5) and the fourth IGBT (6) are turned off; at this time, the first IGBT (3), the inductor (12) and the second freewheeling diode (8) form a BUCK step-down circuit, and the battery/battery Group (1) charges the supercapacitor (11). 10. An energy-saving control method for forklifts according to claim 7, characterized in that: when in the 4th) working state, the fourth signal and the first signal control the fourth IGBT (6) and the first IGBT (3 ) on and off, the third IGBT (5) and the second IGBT (4) are in the off state, and when the cargo of the electric forklift is descending, the double-acting AC motor (13) reverses to become a generator, through the fourth signal and The first signal regulates the switching of the fourth IGBT (6) and the first IGBT (3) to charge the supercapacitor (11).