WO2021256762A1 - Hybrid power generation measurement system for construction machines - Google Patents

Abstract

A hybrid power generation measurement system for construction machines according to one embodiment in the present specification comprises: a power distribution device that is connected to a driving unit and a working unit of a piece of construction equipment and distributes input power; an inverter for a power generation unit which receives an input of three-phase alternating current power from an engine-operated generator for the power generation unit and outputs direct current; a current sensor that is disposed between an output terminal of the inverter for the power generation unit and the power distribution device and measures a current value output from the inverter for the power generation unit; and a control unit which receives the current value sensed by the current sensor and controls the operation of the power distribution device on the basis of the current value.

Description

Hybrid power generation power measurement system for construction machinery

The present invention relates to a hybrid power generation power measurement system for construction machines such as a hybrid wheel loader, and more particularly, to a hybrid power generation power measurement system for a construction machine having an actuator for a power generation unit for power generation/storage.

In general, construction machines including excavators include loading and unloading work of loading on-site materials to a predetermined truck during construction and civil engineering works, excavation work of digging or filling the ground, breaker work such as light soil and rock crushing, soil compaction, etc. It is usefully used to perform various tasks such as compactor work and crusher work such as cutting.

These construction machines are equipped with a diesel engine having high output power as a power source, drive a hydraulic pump connected to the engine using the power of the engine, and convert hydraulic oil discharged from the hydraulic pump to a hydraulic actuator such as a hydraulic motor or a hydraulic cylinder. By supplying it, the required power is supplied to the crawler for the traveling part or the rotation of the tire or the work device such as the boom, arm, or bucket to perform the required work.

However, as a fuel for a diesel engine, diesel is a fossil fuel, so it is gradually depleted. In particular, due to the characteristics of construction machines, fuel consumption is high, and fuel efficiency and operating costs are increased.

As one of the alternatives to solve this problem, the use of electric energy is attracting attention, and the case of construction equipment to which electric power system using electric energy is applied, for example, research on construction machinery to which electric power system is applied to hybrid excavators, wheel loaders, etc. Development is actively underway.

For example, in the hybrid excavator system, an electric power system having a motor and an electric storage device is additionally installed in a general excavator using an engine as a power source, the power of the engine is converted into electric power through a generator, and then using an electric motor. By driving the traveling part and the working part, the overall efficiency of the excavator system can be improved.

The main components added to these hybrid excavator systems include motors, energy storage devices, inverters and converters. Here, the energy storage device includes a battery and an ultra-capacitor (UC).

A hybrid wheel loader, which is one of hybrid construction machines, may require a greater driving force than when driving when excavating or loading trucks using a bucket.

Therefore, the controller mounted on the hybrid wheel loader needs to control the amount of power generation based on information on the required load amount of the connected work machine, the amount of generated electric power, and the remaining charge amount of the battery.

For this purpose, it is required to accurately measure the amount of power generated and usable by the generator for the power generation unit.

An embodiment of the present specification has an object to provide a hybrid power generation power measurement system for construction machinery that measures the amount of power generated and usable by the generator for the power generation unit.

A hybrid power generation power measuring system for a construction machine according to an embodiment of the present specification is a power distribution device connected to a driving unit and a work unit of a construction machine to distribute input power; 3 from a generator operated by an engine an inverter for a power generation unit that receives AC power from the phase and outputs a DC current; and a controller configured to receive a current value sensed by the current sensor and control an operation of the power distribution device based on the current value.

The hybrid power generation power measuring system for a construction machine according to an embodiment of the present specification further includes a battery sensor for measuring the remaining charge amount of a battery connected to the power distribution device. The controller controls power distribution of the power distribution device based on the current value and the remaining charge amount of the battery.

The control unit determines the RPM of the engine and the torque of the generator based on the current value, the remaining battery charge amount, and the required load amount of the work unit and the driving unit.

The hybrid power generation power measurement system for a construction machine according to an embodiment of the present specification includes an initial charging unit disposed between the current sensor and the power distribution device.

The initial charging unit may include: an initial charging resistor connected to the current sensor and the power distribution device; a first relay connected in parallel to the initial charging resistance; and a second relay connected between the initial charging resistor and the power distribution device.

In the initial operation of the inverter for the power generation unit, the first relay is controlled in an open state, the second relay is controlled in a connected state, and in normal operation, the first relay is controlled in a connected state, and the second relay is controlled in the open state.

The inverter for the power generation unit is connected to the AC power supply unit, the switching element for switching the phase of the three-phase AC power input from the AC power supply unit; and a DC link capacitor accumulating the voltage output by the switching element to output a DC current.

A hybrid power generation power measurement system for a construction machine according to an embodiment of the present specification includes an inverter for a power generation unit that receives three-phase AC power from a generator for a power generation unit operated by an engine and outputs a DC current; a control unit for determining the RPM of the engine and the torque of the generator based on the required load; and a current sensor disposed between the output terminal of the inverter for the power generation unit and the control unit, and measuring a current value output from the inverter for the power generation unit. When determining the RPM of the engine and the torque of the generator, the controller is based on a current value measured from the current sensor.

The hybrid power generation power measurement system for construction machinery according to an embodiment of the present specification has the advantage of being able to measure accurate active power delivered to the power distribution device and/or control unit from the generated current generated/stored by the generator for the power generation unit. have.

1 is a view showing a hybrid power generation power measurement system for a construction machine according to an embodiment of the present specification.

2 is a view showing an apparatus for measuring power generation according to an embodiment of the present specification.

3 is a diagram illustrating a connection state of a power sensor according to an embodiment of the present specification.

4 is a diagram illustrating a connection state of a switching element inside a three-phase inverter according to an embodiment of the present specification.

It should be noted that the technical terms used herein are used only to describe specific embodiments, and are not intended to limit the present invention. In addition, the technical terms used in this specification should be interpreted as meanings generally understood by those of ordinary skill in the art to which the present invention belongs, unless otherwise specifically defined in this specification, and excessively inclusive It should not be construed in the meaning of a human being or in an excessively reduced meaning.

Also, as used herein, the singular expression includes the plural expression unless the context clearly dictates otherwise.

In addition, the suffixes "module" and "part" for components used in this specification are given or used in consideration of ease of writing the specification, and do not have a meaning or role distinct from each other by themselves.

Also, terms including ordinal numbers such as first, second, etc. used herein may be used to describe various components, but the components should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component.

Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the accompanying drawings, but the same or similar components are assigned the same reference numerals regardless of reference numerals, and redundant description thereof will be omitted.

Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing a hybrid power generation power measurement system for a construction machine according to an embodiment of the present specification, FIG. 2 is a view showing a generation power measuring device according to an embodiment of the present specification, and FIG. 3 is a diagram of the present specification It is a diagram showing a connection state of a power sensor according to an embodiment. 1 to 3, the hybrid power generation power measurement system for a construction machine according to an embodiment of the present specification includes a generator 110 for a power generation unit, an inverter 120 for a power generation unit, a current sensor 130, and a power distribution device ( 150 ), a control unit 140 , a battery 160 , and a battery sensor 170 .

The generator 110 for the power generation unit is driven at the same speed as the engine RPM to produce three-phase AC power.

The inverter 120 for the power generation unit is connected to the generator 110 for the power generation unit, receives the three-phase AC power produced by the generator 110 for the power generation unit, and outputs direct current.

The inverter 120 for the power generation unit controls the RPM of the engine 10 and the torque of the generator 110 according to the instruction of the control unit 140 .

The inverter 120 for the power generation unit includes a plurality of switching elements and a DC link capacitor 125 .

The DC link capacitor 125 accumulates voltages output from the switching elements of the inverter 120 for the power generation unit, and outputs a DC current.

The current sensor 130 is disposed on one pole of the DC link of the DC link capacitor 125 of the inverter 120 for the power generation unit and the connection line of the power distribution device 150, the DC link terminal of the inverter 120 for the power generation unit. The current is measured and the measured value is transmitted to the controller 140 .

Since the position of the current sensor 130 is located at the output terminal of the inverter 120 for the power generation unit, it is possible to measure the power in which the inverter efficiency is reflected.

More specifically, in general, three-phase AC power generated from a generator generates reactive power by a phase difference. Accordingly, the generator supplies both active power and reactive power to the inverter 120 for the power generation unit. However, only active power is transmitted to the power delivered to the power distribution device 150 , and the reactive power remains in the generator and inverter systems. Therefore, by mounting the current sensor 130 to the DC link terminal of the inverter 120 for the power generation unit to measure the voltage and current, it is possible to calculate the correct active power delivered to the electric power system.

The control unit 140 is constituted by a central processing unit (CPU) and an arithmetic processing unit including an internal memory, and is executed by the CPU executing a drive control program stored in the internal memory.

The controller 140 controls the operation of the power distribution device 150 based on the current value measured by the current sensor 130 .

The control unit 140 calculates the required load amount of the work machine (the driving unit and the work unit), and controls the generator 110 for the power generation unit through the inverter 120 for the power generation unit based on the required load amount of the work machine.

The driving unit 20 is responsible for driving the construction machine and has a plurality of, for example, six actuators. Each actuator includes an inverter and a motor.

The work unit 21 is responsible for the work of the construction machine and has a plurality of, for example, two actuators. Each actuator includes an inverter and a motor.

The construction machine includes a motor for each traveling unit and a motor for the working unit for driving the driving unit 20 and the actuator of the working unit 21, and runs to control the rotational speed of each driving unit motor and the working unit motor It further includes an inverter for a bouillon and an inverter for a work unit.

The driving unit 20 and the working unit 21 are driven by the power distributed by the power distribution device 150 in the embodiment of the present invention.

The controller 140 may calculate the required load amount of the work machine based on power consumed by the work machine by a work machine sensor (not shown) or the like. When a plurality of work machines are included, the total power consumption measured value is calculated by summing the power consumption of each work machine. In addition, the controller 140 may receive a signal indicating an operation amount for operating the work machine according to the operation of the connected user, and calculate a load amount corresponding to the operation amount.

The power distribution device 150 distributes the input current to the connected battery 160 and the working device according to the instruction of the controller 140 . The power distribution device 150 is connected to the initial charging unit 155 and may include a separate internal initial charging unit.

The initial charging unit 155 is connected in series with the current sensor 130 and includes an initial charging resistor R and relays R1 and R2. The initial charging unit 155 may suppress an inrush current that may be initially generated.

3, the initial charging resistor (R) is connected in series with the current sensor 130, the first relay (R1) is connected in parallel to the initial charging resistor (R), the second relay (R2) is It may be connected in series with the initial charging resistor (R).

In the initial operation of the inverter 120 for the power generation unit, the first relay (R1) is controlled to the open state and the second relay (R2) is controlled to the connected state, and the input current is transmitted through the initial charging resistor (R), In a normal operation, the first relay R1 is controlled to be in the connected state and the second relay R2 is controlled to be in the open state, and is transmitted through the first relay R1.

The battery 160 serves to supply power to the starting motor and the ignition device when starting the construction machine. When the engine is stopped, it supplies the power required for the operation of the electrical equipment installed in the construction machine.

The battery sensor 170 is electrically connected to the battery 160 and monitors any one or more of voltage, current, and/or temperature of the battery 160 to check the state of charge and the remaining charge of the battery 160 . .

The battery sensor 170 may be an Intelligent Battery Sensor (IBS). The IBS basically has sensors that sense the voltage, current, and internal temperature of the vehicle battery, respectively, and using the values sensed by each sensor, the remaining battery charge (SOC: State Of Charge) value and the battery life (SOH: State Of) value are used. Health) (or battery capacity deterioration state), battery internal temperature (BTM: Battery Of Model) value, battery start function (SOF: State Of Function) value, etc. can be calculated. Here, the calculation of battery performance factors such as SOC value, SOH value, BTM value, and SOF value is a known technique, and since such calculation process is not the technical gist of the present invention, a detailed description thereof will be omitted.

The battery sensor 170 transmits the monitored information to the control unit 140 .

The control unit 140 receives the measurement values of the current sensor 130 and the battery sensor 170, and comprehensively determines the remaining battery charge (SOC) of the battery and the required load amount of the work machine to generate power of the generator. decide The controller 140 determines the RPM of the engine and the torque of the generator according to the determined power generation.

The following is a table for explaining the generation power measurement efficiency to which the inverter efficiency according to an embodiment of the present invention is applied.

First, as shown below, Table 1 shows fuel efficiency according to the rotational speed of the engine.

data record
Fuel efficiency g/kWh	198.6	196.6	195.8	198.0	197.2
	198.5	196.7	194.9	194.1	195.3
	198.1	197.0	195.6	195.8	195.8
	196.7	197.4	197.5	195.4	198.1
	199.9	197.6	197.2	196.6	197.6
	200.1	202.0	198.3	197.6	199.7
	202.3	203.5	201.4	204.8	208.4
	209.6	210.7	210.7	212.7	214.5
	221.3	224.0	229.4	233.7	232.2
	273.0	272.9	275.5	281.0	293.9
	373.7	375.1	360.2	376.0	417.3
speed	1300	1400	1500	1600	1700

In addition, as shown below, Table 2 shows the torque of the generator according to the rotational speed of the engine.

data record
talk (Nm)	1284.005	1278.898	1287.902	1264.197	1198.480
	1151.211	1148.630	1162.077	1157.175	1084.144
	1019.128	104.568	1018.561	1032.248	966.148
	897.551	897.865	902.984	897.647	837.192
	768.251	764.643	773.255	768.107	726.960
	641.841	644.172	646.470	648.078	607.046
	517.350	511.142	517.207	505.301	479.212
	384.887	388.592	385.744	378.904	357.766
	259.507	261.240	261.346	256.041	240.514
	129.976	134.777	133.314	131.469	124.977
	65.774	68.683	65.304	70.156	58.701
speed (rpm)	1300	1400	1500	1600	1700

In addition, as shown below, Table 3 shows the inverter efficiency according to the rotational speed of the engine and the torque of the generator.

talk (Nm)	data record
2450	83.85	84.85	91.73	94.32
2178	84.39	85.39	91.97	94.38	95
2033	85.05	86.05	92.31	94.44	95.03
1866	85.69	86.69	92.64	94.48	95.04
1742	86.25	87.25	92.85	94.67	95.11	96.7
1528	86.94	87.94	93.19	94.89	95.29	96.7
1310	87.65	88.65	93.45	95.06	95.44	96.69	97.55
1212	87.88	88.88	93.63	95.17	95.5	96.69	97.5
1042	88.16	89.16	93.67	95.2	95.58	96.7	97.44	97.88
969	88.41	89.41	93.73	95.27	95.54	96.72	97.41	97.83	97.9
882	88.5	89.5	93.79	95.27	95.58	96.71	97.39	97.79	97.85
871	88.55	89.55	93.81	95.29	95.61	96.71	97.39	97.76	97.8
831	88.56	89.56	93.8	95.28	95.59	96.68	97.38	97.77	97.79
755	88.39	89.39	93.74	95.19	95.58	96.65	97.33	97.75	97.8	97.9
740	88.44	89.44	93.74	95.2	95.57	96.63	97.31	97.77	97.79	97.88
693	88.41	89.41	93.7	95.16	95.49	96.6	97.3	97.7	97.8	97.38
635	88.38	89.38	93.66	95.1	95.47	96.59	97.28	97.74	97.78	97.83
555	88.26	89.26	93.58	95	95.42	96.53	97.23	97.7	97.76	97.79	97.8
523	88.14	89.14	93.59	94.97	95.34	96.5	97.23	97.7	97.75	97.78	97.73
505	88.13	89.13	93.54	94.93	95.33	96.45	97.2	97.71	97.74	97.76	97.65
465	87.78	88.78	93.49	94.82	95.22	96.39	97.14	97.68	97.72	97.71	97.53
396	87.57	88.57	93.24	94.8	95.07	96.27	97.03	97.59	97.69	97.63	97.49	97.45
356	87.36	88.36	93.08	94.71	95.09	96.19	96.94	97.52	97.63	97.58	97.35	97.3
305	86.93	87.93	92.82	94.48	94.84	95.98	96.79	97.44	97.55	97.51	97.3	97.14
0	85.93	86.93	91.82	93.48	93.84	94.98	95.79	96.44	96.55	96.51	96.3	96.14
speed (rpm)	0	313	531	697	747	994	1250	1563	1719	1875	2188	2500

Referring to Table 3, the efficiency of the inverter is 95.79% to 97.9%, and the efficiency error is 2.11% in the operating region of the inverter, that is, in the region where the engine speed is 1250 or more and 1875 or less and the torque of the generator is 0 to 1528 or less.

In addition, in the case of EV (Electric Vehicle) mode in hybrid use, the engine is switched to On/Off mode and driving and off are repeated. In this case, the driving range of the inverter is changed. As such, in hybrid use, the engine speed in the inverter region in the case of EV is 0 or more and 1250 or less, and the torque of the generator is 0 to 305 or less, and the efficiency of the inverter in this inverter region is 85.93% to 95.98%, and the efficiency error is 10.05%.

In the absence of the current sensor 130, the generated power should be measured with the output current of the generator 110 and the voltage of the DC link capacitor 125 of the inverter 120 for the power generation unit, and in this case, the efficiency of the inverter 120 for the power generation unit If this is not reflected, over-generation or under-generation of the engine/generator may occur due to an efficiency error, which adversely affects the charging/discharging strategy of the hybrid construction machine power system and lowering fuel efficiency, as well as reducing the lifespan or failure of the device. can cause problems such as As described above, the efficiency error of the inverter in the general operation range is 2.11%, which is not a small number in hybrid construction machines that use large power, and in the EV mode, the efficiency error reaches 10.05%, which may cause a bigger problem.

However, according to one embodiment of the present specification, the current sensor 130 is provided (arranged) at the output terminal of the inverter 120 for the power generation unit, so that the final generated power including the efficiency of the inverter can be accurately calculated. Accordingly, the control unit 140 controls the engine 10 so that the most efficient operation is performed based on the remaining battery charge amount, the required load amount of the work unit 21 and the driving unit 20 , and the current value measured by the current sensor 130 . ) of the RPM and the torque of the generator 110 can be determined, and thus the charging/discharging of the construction machine power system can be precisely controlled.

In FIG. 2 of the present specification, the current sensor 130 has been illustrated and described to be disposed outside the power distribution device 150, but the present invention is not limited thereto. It is also possible to be disposed inside the dispensing device 150 and made of one component.

4 is a view showing a connection state of a switching element inside a three-phase inverter according to an embodiment of the present specification.

Referring to FIG. 4 , the switching elements of the three-phase inverter are upper switching elements S1, S2, S3 respectively disposed between the input lines for each of the three phases (U, V, W) and the first pole of the DC link capacitor 125 . ) and lower switching elements S4, S5, and S6 respectively disposed between the input line for each of the three phases (U, V, W) and the second pole of the DC link capacitor 125 .

The switching elements arranged in the same column are connected to the input line for the same phase, and the upper and lower switching elements for U phase are Sa, the upper and lower switching elements for V phase are Sb, and the upper and lower switching elements for the W phase are Sb. The switching element is denoted by Sc.

Here, the two switching elements in the same column, that is, Sa, Sb, and Sc are alternately switched according to the phase of the input voltage to output a DC current.

The inverter included in the hybrid power generation power measurement system for construction machines according to an embodiment of the present invention may use the same model as the inverter connected to the motor used in the working machine of the construction machine.

Those of ordinary skill in the art to which this specification belongs will be able to understand that the present specification may be embodied in other specific forms without changing the technical spirit or essential features thereof. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. The scope of the present specification is indicated by the claims described later rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the present specification. should be interpreted

On the other hand, in the present specification and drawings, preferred embodiments of the present specification have been disclosed, and although specific terms are used, these are only used in a general sense to easily explain the technical content of the present specification and help the understanding of the invention, It is not intended to limit the scope of the specification. It will be apparent to those of ordinary skill in the art to which this specification pertains that other modifications based on the technical spirit of the present specification may be implemented in addition to the embodiments disclosed herein.

<Explanation of code>

110: generator

120: inverter

130: current sensor

140: control unit

150: power distribution device

160: battery

170: battery sensor

Claims (8)

1. a power distribution device connected to the driving unit and the working unit of the construction machine to distribute input power;

   an inverter for the power generation unit that receives three-phase AC power from the generator for the power generation unit operated by the engine and outputs DC current;

   a current sensor disposed between the output terminal of the inverter for the power generation unit and the power distribution device, and measuring a current value output from the inverter for the power generation unit; and

   A hybrid power generation power measurement system for construction machinery comprising: a control unit receiving the current value sensed by the current sensor, and controlling an operation of the power distribution device based on the current value.
2. According to claim 1,

   Further comprising; a battery sensor for measuring the remaining battery charge of the battery connected to the power distribution device;

   The control unit is a hybrid power generation power measurement system for construction machines that controls power distribution of the power distribution device based on the current value and the remaining battery charge amount
3. 3. The method of claim 2,

   The control unit is a hybrid power generation power measurement system for construction machinery that determines the RPM of the engine and the torque of the generator based on the current value, the remaining battery charge amount, and the required load amount of the work unit and the driving unit.
4. The method of claim 1,

   Hybrid power generation power measurement system for construction machines including an initial charging unit disposed between the current sensor and the power distribution device.
5. 5. The method of claim 4,

   The initial charging unit

   an initial charging resistor connected to the current sensor and the power distribution device;

   a first relay connected in parallel to the initial charging resistor; and

   a second relay connected between the initial charging resistor and the power distribution device;

   A hybrid power generation power measurement system for construction equipment comprising a.
6. 6. The method of claim 5,

   In the initial operation of the inverter for the power generation unit, the first relay is controlled in an open state, the second relay is controlled in a connected state, and during normal operation, the first relay is controlled in a connected state, and the second relay is a hybrid power generation power measurement system for construction machinery that is controlled in an open state.
7. The method of claim 1,

   The inverter for the power generation unit is connected to the AC power supply unit, the switching device for switching the phase of the three-phase AC power input from the AC power supply unit; and

   A hybrid power generation power measurement system for construction machines comprising a DC link capacitor accumulating the voltage output by the switching element and outputting a DC current.
8. an inverter for the power generation unit that receives three-phase AC power from the generator for the power generation unit operated by the engine and outputs DC current;

   a control unit for determining the RPM of the engine and the torque of the generator based on the required load amount of the work machine according to the user's operation; and

   It is disposed between the output terminal of the inverter for the power generation unit and the control unit, including a current sensor for measuring a current value output from the inverter for the power generation unit,

   When the control unit determines the RPM of the engine and the torque of the generator, the hybrid power generation power measurement system for construction machinery based on the current value measured from the current sensor.

Images